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Title: A Dictionary of Arts, Manufactures and Mines
       containing a clear exposition of their principles and practice

Author: Andrew Ure

Release Date: January 1, 2014 [EBook #44562]

Language: English

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Transcriber’s Notes

Italicised texts in the original work have been transcribed between
_underscores_; small capitals have been transcribed as CAPITALS.
Superscript c is transcribed as ^{c}. ● and ○ represent a solid and an
open circle with a vertical line, respectively. [S] represents a letter
S rotated 90 degrees. In ([26 × 2] + [40 × 2]) the original work has a
horizontal line over the numbers between the square brackets.

More Transcriber’s notes may be found at the end of this text.




  A
  DICTIONARY
  OF
  ARTS, MANUFACTURES,
  AND
  MINES:
  CONTAINING
  A CLEAR EXPOSITION OF THEIR PRINCIPLES
  AND PRACTICE.

  BY

  ANDREW URE, M.D.
  F.R.S. M.G.S. M.A.S. LOND.; M. ACAD. N.S. PHILAD.; S. PH. SOC. N.
  GERM. HANOV.; MULII. ETC. ETC.

  ILLUSTRATED WITH TWELVE HUNDRED AND FORTY
  ENGRAVINGS ON WOOD.

  Second Edition.

  LONDON:
  PRINTED FOR
  LONGMAN, ORME, BROWN, GREEN, & LONGMANS,
  PATERNOSTER-ROW.

  1840.


  LONDON:
  Printed by A. SPOTTISWOODE,
  New-Street-Square.




PREFACE.


It is the business of operative industry to produce, transform, and
distribute all such material objects as are suited to satisfy the wants
of mankind. The primary production of these objects is assigned to the
husbandman, the fisherman, and the miner; their transformation to the
manufacturer and artisan; and their distribution to the engineer,
shipwright, and sailor.[1] The unworked or raw materials are
derived,--1. from the organic processes of vegetables and animals,
conducted either without or with the fostering care of man; 2. from the
boundless stores of mineral and metallic wealth, arranged upon or within
the surface of the earth by the benignant Parent of our being, in the
fittest condition to exercise our physical and intellectual powers in
turning them to the uses of life.

  [1] For correct and copious information upon _agricultural_
  production, I have great pleasure in referring my readers to Mr.
  Loudon’s elaborate _Encyclopedias of Agriculture, Gardening, and
  Plants_; and for _mercantile_ production and distribution, to Mr.
  M’Culloch’s excellent _Dictionary of Commerce and Commercial
  Navigation_.

The task which I have undertaken in the present work, is to describe and
explain the transformations of these primary materials, by mechanical
and chemical agencies, into general objects of exchangeable value;
leaving, on the one hand, to the mechanical engineer, that of
investigating the motive powers of transformation and transport; and, on
the other hand, to the handicraftsman, that of tracing their
modifications into objects of special or local demand. Contemplated in
this view, an art or manufacture may be defined to be that species of
industry which effects a certain change in a substance, to suit it for
the general market, by combining its parts in a new order and form,
through mechanical or chemical means. Iron will serve the purpose of
illustrating the nature of the distinctions here laid down, between
mechanical engineering; arts and manufactures; and handicraft trades.
The engineer perforates the ground with a shaft, or a drift, to the
level of the ore, erects the pumps for drainage, the ventilating, and
hoisting apparatus, along with the requisite steam or water power; he
constructs the roads, the bridges, canals, railways, harbours, docks,
cranes, &c., subservient to the transport of the ore and metal; he
mounts the steam or water power, and bellows for working the
blast-furnaces, the forges, and the cupolas; his principal end and aim
on all occasions being to overcome the forces of inertia, gravity, and
cohesion. The ores extracted and sorted by the miner, and transported by
the engineer to the smelting station, are there skilfully blended by the
iron-master (manufacturer), who treats them in a furnace appropriately
constructed, along with their due proportions of flux and fuel, whereby
he reduces them to cast iron of certain quality, which he runs off at
the right periods into rough pigs or regular moulds; he then transforms
this crude metal, by mechanical and chemical agencies, into bar and
plate iron of various sizes and shapes, fit for the general market; he
finally converts the best of the bars into steel, by the cementation
furnace, the forge, and the tilt-hammer; or the best of the plates into
tin-plate. When farther worked by definite and nearly uniform processes
into objects of very general demand in all civilized countries, these
iron and steel bars still belong to the domain of manufactures; as, for
example, when made into anchors, chain-cables, files, nails, needles,
wire, &c.; but when the iron is fashioned, into ever varying and
capricious forms, they belong either to the general business of the
founder and cutler, or to the particular calling of some handicraft, as
the locksmith, gratesmith, coachsmith, gunsmith, tinman, &c.

Such are the principles which have served to guide me in selecting
articles for the present volume. By them, as a clue, I have endeavoured
to hold a steady course through the vast and otherwise perplexing
labyrinth of arts, manufactures, and mines; avoiding alike engineering
and mechanical arts, which cause no change in the texture or
constitution of matter,--and handicraft operations, which are multiform,
capricious, and hardly susceptible of scientific investigation. In fact,
had such topics been introduced into the volume, it would have presented
a miscellaneous farrago of incongruous articles, too numerous to allow
of their being expounded in a manner either interesting or instructive
to the manufacturer and the metallurgist. I readily acknowledge,
however, that I have not been able to adhere always so rigorously as I
could have wished to the above rule of selection; having been
constrained by intelligent and influential friends to introduce a few
articles which I would gladly have left to the mechanical engineer. Of
these _Printing_ is one, which, having had no provision made for it in
my original plan, was too hastily compiled to admit of my describing,
with suitable figures, the flat-printing automatic machine of Mr.
Spottiswoode, wherewith the pages of this volume were worked off; a
mechanism which I regard as the most elegant, precise, and productive,
hitherto employed to execute the best style of letter press.

I have embodied in this work the results of my long experience as a
Professor of Practical Science. Since the year 1805, when I entered at
an early age upon the arduous task of conducting the schools of
chemistry and manufactures in the Andersonian Institution, up to the
present day, I have been assiduously engaged in the study and
improvement of most of the chemical and many of the mechanical arts.
Consulted professionally by proprietors of factories, workshops, and
mines, of various descriptions, both in this country and abroad,
concerning derangements in their operations, or defects in their
products, I have enjoyed peculiar opportunities of becoming familiar
with their minutest details, and have frequently had the good fortune to
rectify what was amiss, or to supply what was wanting. Of the stores of
information thus acquired, I have availed myself on the present
occasion; careful, meanwhile, to neglect no means of knowledge which my
extensive intercourse with foreign nations affords.

I therefore humbly hope that this work will prove a valuable
contribution to the literature of science, serving--

_In the first place_, to instruct the Manufacturer, Metallurgist, and
Tradesman, in the principles of their respective processes, so as to
render them in reality the masters of their business, and to emancipate
them from a state of bondage to operatives, too commonly the slaves of
blind prejudice and vicious routine.

_Secondly_, to afford to Merchants, Brokers, Drysalters, Druggists, and
Officers of the Revenue, characteristic descriptions of the commodities
which pass through their hands.

_Thirdly_, by exhibiting some of the finest developments of chemistry
and physics, to lay open an excellent practical school to students of
these kindred sciences.

_Fourthly_, to teach Capitalists, who may be desirous of placing their
funds in some productive bank of industry, to select judiciously among
plausible claimants.

_Fifthly_, to enable Gentlemen of the Law to become well acquainted with
the nature of those patent schemes which are so apt to give rise to
litigation.

_Sixthly_, to present to our Legislators such a clear exposition of our
staple manufactures, as may dissuade them from enacting laws which
obstruct industry, or cherish one branch of it to the injury of many
others: and,

_Lastly_, to give the General Reader, intent chiefly on intellectual
cultivation, a view of many of the noblest achievements of science, in
effecting those grand transformations of matter to which Great Britain
owes her paramount wealth, rank, and power among the kingdoms.

The latest statistics of every important object of manufacture is given,
from the best, and, usually, from official authority, at the end of each
article.[2]

  [2] The statistics of agriculture, trade, and manufactures is ably and
  fully discussed in Mr. M’Culloch’s _Dictionary_ already referred to.

The following summary of our manufactures is extracted from Mr.
Macqueen’s _General Statistics of the British Empire_, published in
1836. It shows the amount of capital embarked in the various
departments of manufacturing industry, and of the returns of that
capital:--

  +----------------------------------+-----------+-----------+
  |                                  |  Capital. |  Produce. |
  |                                  +-----------+-----------+
  |                                  |    _£_    |    _£_    |
  |Cotton manufactures               | 40,973,872| 52,513,586|
  |Woollen  ditto                    | 36,000,000| 44,250,000|
  |Silk     ditto                    |  8,000,000| 10,000,000|
  |Linen    ditto                    | 12,000,000| 15,421,186|
  |Leather  ditto                    | 13,000,000| 16,000,000|
  |Iron     ditto, to making pig iron| 10,000,000|  7,098,000|
  |Ditto, hardware, cutlery, &c.     | 25,000,000| 31,072,600|
  |Copper and brass ditto            |  3,600,000|  4,673,186|
  |China, glass, &c.                 |  8,600,000| 10,892,794|
  |Paper, furniture, books, &c.      | 10,000,000| 14,000,000|
  |Spirits (British), ales, soap, &c.| 37,600,000| 47,163,847|
  |Sundries additional               |           |  9,000,000|
  |                                  +-----------+-----------+
  |            Totals                |204,773,872|262,085,199|
  +----------------------------------+-----------+-----------+

In consequence of an arrangement with Mr. William Newton, patent agent,
and proprietor of the _London Journal of Arts, Sciences, and
Manufactures_, I have been permitted to enrich this Dictionary with many
interesting descriptions and illustrative figures of modern patent
inventions and improvements, which I could not otherwise have presented
to my readers. Mr. Newton has lately enhanced the value of his Journal
by annexing to it a _catalogue raisonnée_, entitled “An Analytical Index
to the Subjects contained in the 23 Volumes,” which constitute the first
and second series. The subsequent 13 volumes, of his Conjoined Series,
are of still superior interest; and the whole form a vast storehouse of
Mechanical and Chemical Invention.

Although I am conscious of having used much diligence for many years in
collecting information for this work, from every quarter within my
reach, the utmost pains in preparing it for publication, and incessant
vigilance during its passage through the press, yet I am fully aware
that it must contain several errors and defects. These I shall study to
rectify, should the Public deem this volume worthy of a supplement. In
this hope, I earnestly solicit the suggestions of my readers; trusting
that ere long our Post Office system will cease to be such an obstacle
as it has long been to the collection and diffusion of useful knowledge,
and a tax upon science which the remuneration of its literature cannot
by any means bear.

Since this book is not a Methodical Treatise, but a Dictionary, one
extensive subject may be necessarily dispersed through many articles.
Thus, for example, information upon the manufacture of _Colours_ will be
found under azure; black pigment; bone-black; bronze; brown dye;
calico-printing; carmine; carthamus; chromium; cochineal; crayons;
dyeing; enamels; gold; gilding; gamboge; gray dye; green dye; green
paints; indigo; kermes; lac dye; lakes; madder; massicot; mercury,
periodide of; Naples yellow; orange dye; orpiment; paints, grinding of;
ochres; paper-hangings; pastes; pearl white; Persian berries; pottery
pigments; Prussian blue; purple of Cassius; red lead; rouge; Scheele’s
green; Schweinfurth green; stained glass; terra di Sienna; ultramarine;
umber; verditer; vermilion; vitrifiable colours, weld, white lead; woad;
yellow, king’s.

A casual consulter of the Dictionary, who did not advert to this
distribution, might surmise it to be most deficient, where it is in
reality most copious.

The elaborate and costly Encyclopedias, and Dictionaries of Arts, which
have appeared from time to time in this country, and abroad, have, for
the most part, treated of the mechanical manufactures, more fully and
correctly than of the chemical. The operations of the former are, in
fact, tolerably obvious and accessible to the inspection of the curious;
nor are they difficult to transfer into a book, with the aid of a
draughtsman, even by a person but moderately versed in their principles.
But those of the latter are not unfrequently involved in complicated
manipulations, and depend, for their success, upon a delicate play of
affinities, not to be understood without an operative familiarity with
the processes themselves. Having enjoyed the best opportunities of
studying the chemical arts upon the greatest scale in this kingdom and
on the Continent, I may venture, without the imputation of arrogance, to
claim for my work, in this respect, more precision and copiousness than
its predecessors possess. I have gone as far in describing several
curious processes, hitherto veiled in mystery, as I felt warranted,
without breach of confidence, to go; regarding it as a sacred duty never
to publish any secret whatever, without the consent of its proprietor.
During my numerous tours through the factory districts of Great Britain,
France, &c., many suggestions, however, have been presented to my mind,
which I am quite at liberty to communicate in private, or carry into
execution, in other districts too remote to excite injurious competition
against the original inventors. I am also possessed of many plans of
constructing manufactories, of which the limits of this volume did not
permit me to avail myself, but which I am ready to furnish, upon
moderate terms, to proper applicants. I conclude by pointing attention
to the very insecure tenure by which patents for chemical or
chemico-mechanical inventions are held; of which there is hardly one on
record which may not be readily evaded by a person skilled in the
resources of practical chemistry, or which could stand the ordeal of a
court of law directed by an experienced chemist. The specifications of
such patents stand in need of a thorough reform; being for the most part
not only discreditable and delusive to the patentees, but calculated to
involve them in one of the greatest of evils--a chancery suit.

  LONDON:
  13. Charlotte Street, Bedford Square,
  March 1. 1839.


DR. URE is preparing for publication, in one large volume, 8vo.,
CHEMISTRY IN THEORY AND PRACTICE; embodying a New System of Research, of
such facility and precision, as will enable chemical manufacturers of
every class, medical practitioners, metallurgists, farmers, merchants,
brokers, druggists, drysalters, officers of the revenue, as well as
general students, to analyze their respective objects in much less time
than is usually required at present by professional chemists. A
descriptive Index will be annexed for converting this systematic work
into a Dictionary of Chemical Science.




  A
  DICTIONARY
  OF
  ARTS, MANUFACTURES, AND MINES.


ABB-WOOL. Among clothiers, this term signifies the _woof_ or _weft_.


ACETATE. (_Acétate_, Fr.; _Essigsäure_, Germ.) Any saline compound of
which the acetic is the acid constituent; as acetate of soda, of iron,
of copper, &c.


ACETATE OF ALUMINA, see RED LIQUOR and MORDANT; of COPPER, see COPPER;
of IRON, see IRON; of LEAD, see LEAD; of LIME, see PYROLIGNOUS ACID.


ACETIC ACID (_Acide Acétique_, Fr.; _Essigsäure_, Germ.) is the name of
the sour principle which exists in vinegar. It occurs, ready formed, in
several products of the vegetable kingdom, and is generated during the
spontaneous fermentation of many vegetable and animal juices. The
_sambucus nigra_, or black elder, the _phœnix dactilifera_, and the
_rhus typhinus_ are plants which afford a notable quantity of vinegar.
It is found, likewise, in the sweat, urine, milk, and stomach of
animals. All infusions of animal or vegetable matters in water, when
exposed for some time to the air, at a moderate temperature, ferment
into vinegar; and most vegetables, when subjected to decomposition by
fire, give off condensable vapours of acetic acid. All liquids
containing alcohol are susceptible of passing into the state of vinegar;
but the pre-existence of alcohol is not necessary to this change, as we
learn from the acetification of vegetable soups, infusion of cabbage,
starch--paste, &c.

Vinegar may be distinguished into four varieties, according to the mode
of its production, though all of them are capable of being converted, by
chemical means, into one identical acetic acid. 1. Wine vinegar. 2. Malt
vinegar. 3. Sugar vinegar. 4. Wood vinegar, or pyrolignous acid.
Fermentation is the source of the acid in the first three varieties.
Here alcohol is first generated, and is next converted into vinegar by
the influence of the air at a genial temperature; a change which will be
investigated under FERMENTATION. But the conversion of spirit of wine
into acetic acid may be demonstrated by direct experiment. When the
vapour of alcohol is brought into contact in the atmosphere with the
black powder obtained by mixing muriate of platina, potash, and alcohol,
vinegar is rapidly formed at the expense of the alcohol. In Germany,
where crude alcohol bears a low price, the manufacture of vinegar has
been arranged upon that principle, which, as throwing some light on the
process of acetification, I shall briefly describe. See PLATINUM _for
the mode of preparing the above powder_.

Under a large case, which for experimental purposes may be made of
glass, several saucer-shaped dishes of pottery or wood are to be placed
in rows, upon shelves over each other, a few inches apart. A portion of
the black platina powder moistened being suspended over each dish, let
as much vinous spirits be put into them as the oxygen of the included
air shall be adequate to acidify. This quantity may be inferred from the
fact, that 1000 cubic inches of air can oxygenate 110 grains of absolute
alcohol, converting them into 122 grains of absolute acetic acid, and
64-1/2 grains of water.

The above simple apparatus is to be set in a light place (in sunshine,
if convenient), at a temperature of from 68° to 86° Fahr., and the
evaporation of the alcohol is to be promoted by hanging several leaves
of porous paper in the case, with their bottom edges dipped in the
spirit. In the course of a few minutes, a most interesting phenomenon
will be perceived. The mutual action of the platina and the alcohol will
be displayed by an increase of temperature, and a generation of acid
vapours, which, condensing on the sides of the glass-case, trickle in
streams to the bottom. This striking transformation continues till all
the oxygen of the air be consumed. If we wish, then, to renew the
process, we must open the case for a little, and replenish it with air.
With a box of 12 cubic feet in capacity, and with a provision of 7 or 8
ounces of the platina powder we can, in the course of a day, convert
one pound of alcohol into pure acetic acid, fit for every purpose,
culinary or chemical. With from 20 to 30 pounds of the platina powder
(which does not waste), we may transform, daily, nearly 300 pounds of
bad spirits into the finest vinegar. Though our revenue laws preclude
the adoption of this elegant process upon the manufacturing scale in
this country, it may be regarded as one of the greatest triumphs of
chemistry, where art has rivalled nature in one of her most mysterious
operations.

To readers acquainted with chemical symbols, the following numerical
representation of the conversion of alcohol into acetic acid may be
acceptable:--

  580·64 parts by weight of alcohol  = H¹² C⁴ O² consist of
   74·88                 of hydrogen = H¹²
  305·76                 of carbon   = C⁴
  200·00                 of oxygen   = O²

If we combine with this mixture, 400 parts of oxygen = O⁴, we have,--

  of water    = 337·44 = H⁶ O³
  acetic acid = 643·20 = H⁶ C⁴ O³

Hence, in this formation of vinegar, 100 parts by weight of alcohol take
68·89 parts of oxygen; and there are produced 58·11 parts of water, and
110·78 of acetic acid.

These beautiful experiments prove, that when in a mere mixture of
alcohol and water, under the influence of the atmospheric air and heat,
some vinegar comes to be formed after a considerable time, the same
formation of vinegar takes place in a similar, but more effective,
manner, when a ferment is present, which acts here in a somewhat
analogous way to the platina powder in the preceding case. Several
azotized substances serve as re-agents towards the acetous
fermentation,--such as vinegar ready-made, vinegar-yeast, or lees,
barley bread, leaven, beer barm, and similar vegetable matters, which
contain gluten. The best and purest ferment is, however, vinegar itself.
With this ferment we must conjoin, as an essential condition of
acetification, the free access of atmospheric air.

It is a well-known fact, that spirituous liquors, as weak brandy, wine,
and beer, &c., may be preserved for years in close vessels, without
undergoing the acetous fermentation, even when they repose upon a layer
of lees. It is equally well known, that these very liquors, if they
stand for some time in open vessels, become readily sour, especially if
exposed, also, to a somewhat high temperature. If we fill a flask with
common brandy, and subject it, without a stopper, to the influence of
air and warmth, the contained liquor may, at the end of many weeks,
discover no sensible acidity: if we add to the same brandy a ferment,
and stop the flask air-tight, everything will still remain unchanged;
but if we leave a portion of air in the flask, or leave it uncorked,
vinegar will soon make its appearance in the brandy.

If we investigate the nature of the air which remains over brandy in the
act of acetification, we shall find that it consists entirely of
carbonic acid and azote, the oxygen being absorbed and combined in the
acetic acid and water formed.

Since this absorption of oxygen from the air can take place only at the
surface of the fermenting liquors, we thus see the necessity and the
practical importance of amplifying that surface, in order to accelerate
and complete the acetification, by multiplying the points of contact
between the alcohol and the oxygen. The essence of the new German method
of rapid acetification depends upon this principle.

Temperature has also a remarkable influence on the formation of vinegar.
The acid fermentation proceeds very feebly in the cold, but takes an
accelerated pace as the heat is raised. It would even appear that
spirituous vapours brought by themselves in contact with atmospheric
air, without the aid of any ferment, are capable of being converted into
acetic acid, since it has happened in the rectification of brandy, in a
still furnished with a large capital and adopter pipe into which air was
allowed to enter, that vinegar made its appearance. Hence, warmth does
not seem to act as a promoter of the combination of alcohol with oxygen
in a merely chemical point of view, but it acts, so to speak,
physically. Over the warm liquor a stratum of spirit vapour appears to
float, which, coming there into conflict with the atmospherical oxygen,
probably causes the generation of some acetic acid, and thus accelerates
the operation, much more than by the mere contact of the oxygen with the
liquid surface.

When we expose any spirituous liquors, as wine, beer, &c., with the
requisite ferment, to the external air, at a temperature of from 64° to
68° Fahr., the fluid, however clear before, becomes soon turbid;
filamentous slimy particles begin to appear moving in the middle and on
the sides of the vessel, and then form a scum on the top of the liquor.
When this scum has acquired a certain thickness and consistence, it
falls in a sediment to the bottom. The Germans call it the vinegar
_mother_, as it serves to excite acetification in fresh liquors.
Meanwhile, the liquor has become warmer than the surrounding air, and
the vinegar process betrays itself by diffusing a peculiar aroma in the
apartment. Whenever all the alcohol present has been converted into
acetic acid, the liquor comes into a state of repose; its temperature
sinks to the pitch of the atmosphere; it becomes bright, and is the
article well known by its taste and smell under the name of vinegar.

Genuine wine or raisin vinegar differs from that formed either from
apples, or sugar, beer, &c., in containing wine-stone or tartar; by
which peculiarity it may be distinguished, except in those cases where
crude tartar has been artificially added to the other vinegars, as a
disguise. Barley-malt vinegar contains some phosphoric acid, in the
state of phosphate of lime or magnesia, derived from the grain.

After these general observations upon acetification, we shall now
proceed to describe the processes for manufacturing vinegar on the
commercial scale.

1. _Wine vinegar._--The first consideration with a vinegar maker is a
good fermenting room, in which the wines may be exposed to a steady
temperature, with an adequate supply of atmospherical air. As this air
is soon deprived of its oxygenous constituent, facilities ought to be
provided for a renewal of it by moderate ventilation. The air holes for
this purpose ought to be so contrived that they may be shut up when the
temperature begins to fall too low, or in windy weather. The best mode
of communicating the proper warmth to a chamber of this kind is by means
of fire-flues or hot water pipes, running along its floor at the sides
and ends, as in a hothouse; the fireplace being on the outside, so that
no dust may be created by it within. The flue is best made of bricks,
and may have a cross section of 10 or 12 inches by 15 deep. The soot
deposited, even when coals are burned, will find ample space in the
bottom of the flue, without interfering essentially with the draught,
for a very long period, if it be made of the above dimensions.
Low-roofed apartments are preferable to high ones; and those built with
thick walls, of imperfectly conducting materials, such as bricks, lined
with lath and plaster work. Should the chamber, however, have a high
ceiling, the fermenting tuns must be raised to a suitable height on
scaffolding, so as to benefit by the warmest air. Sometimes the vinegar
vessels are placed at different levels; in which case the upper ones
acetify their contents much sooner than the under, unless they are
emptied and filled alternately, which is a good plan.

Orleans is the place most famous for vinegars. The building there
destined to their manufacture is called a _vinaigrerie_, and is placed,
indifferently, either on the ground floor or the floor above it; but it
has always a southern exposure, to receive the influence of the
sunbeams. The vessels employed for carrying on the fermentation are
casks, called _mothers_. Formerly they were of a large capacity,
containing about 460 litres (115 gallons, Eng.); but at the present day
they are barrels of half that capacity, or somewhat less than an old
English hogshead. It is now known that the wine passes sooner into
vinegar the smaller the mass operated upon, the more extensive its
contact with the air, and the more genial its warmth. These casks were
formerly arranged in three ranks by means of massive scaffolding; they
are now set in four ranks, but they rest on much smaller rafters,
sustained by uprights, and can be packed closer together. The casks,
which are laid horizontally, are pierced at the upper surface of their
front end with two holes: one, to which the name of _eye_ is given, is
two inches in diameter; it serves for putting in the charge, and drawing
off the vinegar when it is made; the other hole is much smaller, and is
placed immediately alongside; it is merely an air hole, and is necessary
to allow the air to escape, because the funnel completely fills the
other hole in the act of filling the cask.

When new vessels are mounted in a vinegar work, they must be one third
filled with the best vinegar that can be procured, which becomes the
true _mother_ of the vinegar to be made; because it is upon this portion
that the wine to be acidified is successively added. At the ordinary
rate of work, they put at first upon the _mother_, which occupies one
third of the vessel, a _broc_ of 10 litres of red or white wine; eight
days afterwards they add a second _broc_; then a third, and a fourth,
always observing the same interval of time, 8 days. After this last
charge, they draw off about 40 litres of vinegar, and then recommence
the successive additions.

It is necessary that the vessel be always one third empty if we wish the
acetification to go on steadily; but as a portion of the tartar and the
lees forms and accumulates in the lower part of the cask, so as
eventually to counteract the fermentation, the time arrives when it is
requisite to interrupt it, in order to remove this residuum, by clearing
out all the contents. The whole materials must be renovated every 10
years; but the casks, if well made and repaired, will serve for 25
years.

We have mentioned a definite period at which the vinegar may be drawn
off; but that was on the supposition that the process had all the
success we could wish: there are circumstances, difficult to appreciate,
which modify its progress, as we shall presently show. We ought,
therefore, before discharging the vinegar, to test and see if the
fermentation has been complete. We proceed as follows: we plunge into
the liquor a white stick or rod, bent at one end, and then draw it out
in a horizontal direction: if it be covered with a white thick froth, to
which is given the name of _work_ (_travail_), we judge that the
operation is terminated; but if the work, instead of being white and
pearly, be red, the manufacturers regard the fermentation to be
unfinished, and they endeavour to make it advance, by adding fresh wine,
or by increasing the heat of the apartment.

It is not always easy to explain why the fermentation does not go on as
rapidly in one case as in another. There are even certain things which
seem at present to be entirely inexplicable. It happens sometimes, for
example, that although all the vessels have been equally charged, and
with the same wine, yet the fermentation does not form in the same
manner in the whole; it will move rapidly in some, be languid, or
altogether inert, in others. This is a very puzzling anomaly; which has
been ascribed to electrical and other obscure causes, because it is not
owing to want of heat, the casks in the warmest positions being
frequently in fault; nor to the timber of the cask. It, however,
paralyses the process so completely that the most expert vinegar makers
have nothing else for it, when this accident happens, than to empty
entirely what they call the lazy cask, and to fill it with their best
vinegar. The fermentation now begins, and proceeds as well in it as in
the others. See FERMENTATION.

We must here make an important remark, relatively to the temperature
which should prevail in the fermentation room. In many chemical works we
find it stated, that the heat should not exceed 18° R., or 65° Fahr.,
for fear of obtaining bad products. But the vinegar makers constantly
keep up the heat at from 24° to 25° R., 75° to 77° F.; when the
acetification advances much more rapidly, and the vinegar is equally
strong. The best proof of this heat not being too high is, that under
it, the vessels in the upper part of the room, work best and quickest.
In Orleans, cast-iron stoves and wood fuel are used for communicating
the requisite warmth.

Before pouring the wine into the _mothers_, it is clarified in the
following manner. There are tuns which can contain from 12 to 15 pieces
of wine. Their upper end has at its centre an opening of four or five
inches diameter, which may be closed afterwards with a wooden cover;
this opening is for the purpose of receiving a large funnel. The inside
of the tun is filled with chips of beechwood, well pressed down. The
wine is poured upon these chips, allowed to remain for some time, and
then gently drawn off by a pipe in the lower part of the vessel. The
lees are deposited upon the chips, and the wine runs off quite clear.
However, it happens sometimes, notwithstanding this precaution, that the
vinegar, after it is made, requires to be clarified, more particularly
if the wine employed had been weak. The vinegar must be filtered in the
same way; and it derives an advantage from it, as the products of
different casks get thereby mixed and made uniform.

By this Orleans method several weeks elapse before the acetification is
finished; but a plan has been lately devised in Germany to quicken
greatly the acid fermentation by peculiar constructions. This system is
called, the _quick_ vinegar work, because it will complete the process
in the course of 2 or 3 days, or even in a shorter time. It depends,
chiefly, upon the peculiar construction of the fermenting vessels,
whereby the vinous liquor is exposed on a vastly expanded surface to the
action of the atmospheric air.

An oaken tub, somewhat narrower at the bottom than the top, from 6 to 7
feet high and 3 feet in diameter, is furnished with a well-fitted
grooved, but loose, cover. About half a foot from its mouth, the tub has
a strong oak or beech hoop fitted to its inside surface, sufficiently
firm to support a second cover, also well fitted, but moveable. The
space under this second cover is destined to contain the vinous liquor,
and in order to bring it very amply into contact with the atmosphere,
the following contrivances have been resorted to: This cover is
perforated, like a sieve, with small holes, of from 1 to 2 lines in
diameter, and about 1-1/2 inch apart. Through each of these holes a wick
of pack-thread or cotton is drawn, about 6 inches long, which is
prevented from falling through by a knot on its upper end, while its
under part hangs free in the lower space. The wicks must be just so
thick as to allow of the liquor poured above the cover passing through
the holes in drops. The edges of the lid must be packed with tow or hemp
to prevent the liquor running down through the interval.

The whole lower compartment is now to be filled with chips of beechwood
up to nearly the perforated cover. The liquor, as it trickles through
the holes, diffuses itself over the chips, and, sinking slowly, collects
at the bottom of the tub. The chips should be prepared for this purpose
by being repeatedly scalded in boiling water, then dried, and imbued
with hot vinegar. The same measures may also be adopted for the tub. To
provide for the renewal of the air, the tub is perforated at about a
foot from its bottom with eight holes, set equally apart round the
circumference, two thirds of an inch wide, and sloping down, through
which the air may enter into this lower compartment, without the
trickling liquor being allowed to flow out. In order that the foul air
which has become useless may escape, four large holes are pierced in
the sieve cover, at equal distances asunder and from the centre, whose
united areas are rather smaller than the total areas of the holes in the
side of the tub. Into these four holes open glass tubes must be
inserted, so as to stand some inches above the cover, and to prevent any
of the liquor from running through them. The proper circulation of the
air takes place through these draught holes. This air may afterwards
pass off through a hole of 2-1/2 inches diameter in the uppermost cover,
in which a funnel is placed for the supply of liquor as it is wanted to
keep up the percolation.

The temperature of the fermenting compartment is ascertained by means of
a thermometer, whose bulb is inserted in a hole through its side, and
fastened by a perforated cork. The liquor collected in the under vessel
runs off by a syphon inserted near its bottom, the leg of which turns up
to nearly the level of the ventilating air pipes before it is bent
outwards and downwards. Thus the liquor will begin to flow out of the
under compartment only when it stands in it a little below the sieve
cover, and then it will run slowly off at the inclined mouth of the
syphon, at a level of about 3 inches below the lower end of the glass
tubes. There is a vessel placed below, upon the ground, to receive it.
The tub itself is supported upon a wooden frame, or a pier of brickwork,
a foot or 18 inches high.

A tub constructed like the above is called a GRADUATION VESSEL, which
see. It is worked in the following way:--The vinegar room must be, in
the first place, heated to from 100° to 110° F., or till the thermometer
in the graduation vessel indicates at least 77°. The heat may then be
modified. We now pour through the uppermost cover of the tub a mixture,
warmed to 144° F., of 8 parts proof spirits, 25 parts soft water, 15
parts of good vinegar, and as much clear wine or beer. The water should
be first heated, and then the vinegar, spirits, and wine may be added to
it. Of this mixture, so much should be poured in as is necessary to
cover over the second lid, 2 or 3 inches deep, with the liquor; after
which, the rest may be poured slowly in, as it is wanted.

When the liquor has run for the first time through the graduation
vessel, it is not yet sufficiently acidified; but the weak vinegar
collected in the exterior receiving cistern must be a second time, and,
if need be, a third time, passed through the graduation tub, in order to
convert all the alcohol into acetic acid. In general, we may remark,
that the stronger the vinous liquor the more difficult and tedious is
its conversion into vinegar, but it is so much the stronger. To lessen
this difficulty somewhat, it would be well not to put all the spirits at
first into the wash, or mixed liquors, but to add a little more of it at
the second and the third running, especially when we desire to have very
strong vinegar.

After the graduation vessel has been some days at work, it is no longer
necessary to add vinegar to the mixture of spirits and water, since the
sides of the graduation tub, the beech chips, and the packthreads, are
all impregnated with the ferment, and supply its place. The mixture
must, however, be always maintained at the temperature of 100°.

Instead of the above mixture of brandy, water, and wine, we may employ,
according to Dingler, a clear fermented wort of malt, mixed with a
little spirits. The perfect vinegar, which collects in the receiving
cistern, may be immediately racked off into the store casks for sale.

It has been objected to this process, that, in consequence of the
mixture of saccharine and glutinous materials, which are contained in
beer or worts, along with the acetous fermentation, there is also,
partially, a vinous fermentation, and much carbonic acid, thereby
disengaged, so as to obstruct the acetification. This obstruction may be
remedied by a freer circulation of air, or by the exposure of quicklime
in the chamber. It is a more substantial objection, that, from the
addition of beer, &c., more lees, or dregs, are deposited in the
graduation tub, whereby a more frequent cleansing of it, and of the
beech chips, with a loss of time and vinegar, becomes necessary. The
only mode of obviating this difficulty is, to take well-clarified
fermented wash.

Another evil attendant on the quick process is, the evaporation of the
spirituous liquors. Since, in the graduation tub, there is a temperature
of 110°, it is impossible to avoid a loss of spirit from the circulation
and efflux of the air. The air, indeed, that issues from the top hole in
the uppermost cover, might be conducted over an extensive surface of
fresh water, where its spirit would be condensed in a great measure.
But, after all, this fear of great loss is, I believe, groundless;
because the spirit is rapidly acidified by the oxygen of the air, and
thereby rapidly loses its volatility.

The supply of the warm wash should be drawn from a cistern placed near
the ceiling, where the temperature of the apartment is hottest; and it
may be replenished from the partly acetified liquor in the cistern on
the floor. With this view, two cisterns should be placed above, so that
one of them may always contain liquor sufficiently hot, and thus the
process will suffer no interruption.

When malt wash is used for this quick process, the resulting vinegar
must be clarified in a tun with beech chips, as above described. In two
or three days the impurities will be deposited, and the fine vinegar may
be racked off.

The following prescription, for preparing what he calls malt wine, is
given by Dr. Kastner. Eighty pounds of pale barley malt, and 40 pounds
of pale wheat malt, are to be crushed together. These 120 pounds are to
be infused with 150 quarts of water, at the temperature of 122° Fahr.,
afterwards with 300 quarts of boiling water, and the whole body is to be
mashed thoroughly, till all the lumps disappear. It is then to be left
at rest in a large covered tub, for two or three hours, to allow the
grains to settle down, from which the wort is to be drawn off. When it
has fallen to the temperature of 64° Fahr., 15 pounds of good yeast are
to be stirred in, and it must now be left for two or three days to
ferment, in a loosely covered tun. When the vinous fermentation has
taken place, the clear liquor must be drawn off by a tap hole, a little
above the bottom, so as to leave the lees and scum in the tun. This malt
wine, he adds, may be kept for a long time in close vessels, and is
always ready for making quick vinegar.

2. _Malt Vinegar._--The greater part of British vinegar is made from
malt, by the following process:--1 boll of good barley malt, properly
crushed, is to be mashed with water at 160° Fahr. The first water should
have that temperature; the second must be hotter than 160°, and the
third water, for the extraction of all the soluble matter, may be
boiling hot. Upon the whole, not more than 100 gallons of wort should be
extracted. After the liquor has cooled to 75° Fahr., 3 or 4 gallons of
beer yeast are poured in, and well mixed with a proper stirrer. In 36 or
40 hours, according to the temperature of the air, and the fermenting
quality of the wash, it is racked off into casks, which are laid upon
their sides in the fermenting apartment of the vinegar work, which
should be kept at a temperature of 70° at least; in summer partly by the
heat of the sun, but in general by the agency of proper stoves, as above
described. The bung-holes should be left open, and the casks should not
be full, in order that the air may act over an extensive surface of the
liquor. It would be proper to secure a freer circulation to the air, by
boring a hole in each end of the cask, near its upper edge. As the
liquor, by evaporation, would be generally a few degrees colder than the
air of the apartment, a circulation of air would be established in at
the bung-hole, and out by the end holes. By the ordinary methods, three
months are required to make this vinegar marketable, or fit for the
manufacture of sugar of lead.

In making vinegar for domestic purposes, the casks are usually set on
their ends; and they have, sometimes, a false bottom, pierced with
holes, placed about a foot above the true one. On this bottom, a
quantity of _rape_, or the refuse raisins, &c. from the making of
British wines, is laid. The malt liquor has a proper quantity of yeast
added to it. In about 24 hours it becomes warm, and is then racked off
into another similar cask. After some time, this racking process is
discontinued, and the vinegar is allowed to complete its fermentation
quietly. The proper temperature must always be kept up, by placing the
cask in a warm situation. A little wine-stone (_argal_) added to the
malt wash, would make the vinegar liker that made from wine. Sometimes a
little isinglass is employed to clarify vinegar. A portion of sulphuric
acid is often added to it.

3. _Sugar vinegar._--By pursuing the following plan, an excellent sugar
vinegar may be made. In 158 quarts of boiling water dissolve 10 pounds
of sugar, and 6 pounds of wine-stone; put the solution into a fermenting
cask, and when it is cooled to the temperature of from 75° to 80°, add 4
quarts of beer yeast to it. Stir the mixture well, then cover the vessel
loosely, and expose it for 6 or 8 days to the vinous fermentation, at a
temperature of from 70° to 75° Fahr. When it has become clear, draw off
the vinous liquor, and either acetify it in the graduation tub above
described, or by the common vinegar process. Before it is finished, we
should add to it 12 quarts of strong spirits (brandy), and 15 quarts of
good vinegar, to complete the acetous fermentation. With a graduation
tub which has been used, this addition of vinegar is unnecessary.

The following simpler prescription for making sugar vinegar deserves
attention. For every gallon of hot water take 18 ounces of sugar; and
when the syrup has cooled to 75°, add 4 per cent., by measure, of yeast.
When the vinous fermentation is pretty well advanced, in the course of 2
or 3 days, rack off the clear wash from the lees into a proper cask, and
add 1 ounce of wine-stone, and 1 of crushed raisins, for every gallon of
water. Expose it in a proper manner, and for a proper time, to the
acetifying process; and then rack off the vinegar, and fine it upon
beech chips. It should be afterwards put into bottles, which are to be
well corked.

Vinegar obtained by the preceding methods has always a yellowish or
brownish colour. It may be rendered colourless by distillation. For
nicer chemical purposes, this is done in a glass retort; but on a large
scale, it is usually performed in a clean copper still, furnished with a
capital and worm-refrigeratory, either of silver or block tin. It is
volatile at the boiling temperature of water; and if the process be
carried on briskly, it will not sensibly corrode the copper. But we can
never obtain, in this way, a strong article; for, as soon as the vinegar
gets concentrated to a certain degree, we cannot force off the
remainder by heat, for fear of giving it an empyreumatic odour; because
the gluten, colouring matter, &c. begin to adhere to the bottom of the
still. We are, therefore, obliged to suspend the operation at the very
time when the acid is acquiring strength. It has been also proposed to
concentrate vinegar by the process of congelation; but much of it
remains entangled among the frozen water; and common distilled vinegar
is so weak, that it congeals in one mass.

[Illustration: _Fig._ 1.]

Before the process for pyrolignous acid, or wood vinegar, was known,
there was only one method of obtaining strong vinegar practised by
chemists; and it is still followed by some operators, to prepare what is
called radical or aromatic vinegar. This consists in decomposing, by
heat alone, the crystallised binacetate of copper, commonly, but
improperly, called distilled verdigris. With this view, we take a
stoneware retort, (_fig._ 1.) of a size suited to the quantity we wish
to operate upon; and coat it with a mixture of fire clay and horsedung,
to make it stand the heat better. When this coating is dry, we introduce
into the retort the crystallised acetate slightly bruised, but very dry;
we fill it as far as it will hold without spilling when the beak is
considerably inclined. We then set it in a proper furnace. We attach to
its neck an adopter pipe, and two or three globes with opposite
tubulures, and a last globe with a vertical tubulure. The apparatus is
terminated by a Welter’s tube, with a double branch; the shorter issues
from the last globe, and the other dips into a flask filled with
distilled vinegar. Every thing being thus arranged, we lute the joinings
with a putty made of pipeclay and linseed oil, and cover them with glue
paper. Each globe is placed in a separate basin of cold water, or the
whole may be put into an oblong trough, through which a constant stream
of cold water is made to flow. The tubes must be allowed a day to dry.
Next day we proceed to the distillation, tempering the heat very nicely
at the beginning, and increasing it by very slow degrees till we see the
drops follow each other pretty rapidly from the neck of the retort, or
the end of the adopter tube. The vapours which pass over are very hot,
whence a series of globes are necessary to condense them. We should
renew, from time to time, the water of the basins, and keep moist pieces
of cloth upon the globes; but this demands great care, especially if the
fire be a little too brisk, for the vessels become, in that case, so
hot, that they would infallibly be broken, if touched suddenly with cold
water. It is always easy for us to regulate this operation, according to
the emission of gas from the extremity of the apparatus. When the air
bubbles succeed each other with great rapidity, we must damp the fire.

The liquor which passes in the first half hour is weakest; it proceeds,
in some measure, from a little water sometimes left in the crystals,
which when well made, however, ought to be anhydrous. A period arrives
towards the middle of the process when we see the extremity of the beak
of the retort, and of the adopter, covered with crystals of a lamellar
or needle shape, and of a pale green tint. By degrees these crystals are
carried into the condensed liquid by the acid vapours, and give a colour
to the product. These crystals are merely some of the cupreous salt
forced over by the heat. As the process approaches its conclusion, we
find more difficulty in raising the vapours; and we must then augment
the intensity of the heat, in order to continue their disengagement.
Finally, we judge that the process is altogether finished, when the
globes become cold, notwithstanding the furnace is at the hottest, and
when no more vapours are evolved. The fire may then be allowed to go
out, and the retort to cool.

As the acid thus obtained is slightly tinged with copper, it must be
rectified before bringing it into the market. For this purpose we may
make use of the same apparatus, only substituting for the stoneware
retort a glass one, placed in a sand bath. All the globes ought to be
perfectly clean and dry. The distillation is to be conducted in the
usual way. If we divide the product into thirds, the first yields the
feeblest acid, and the third the strongest. We should not push the
process quite to dryness, because there remains in the last portions
certain impurities, which would injure the flavour of the acid.

The total acid thus obtained forms nearly one half of the weight of the
acetate employed, and the residuum forms three tenths; so that about two
tenths of the acid have been decomposed by the heat, and are lost. As
the oxide of copper is readily reduced to the metallic state, its oxygen
goes to the elements of one part of the acid, and forms water, which
mingles with the products of carbonic acid, carburetted hydrogen, and
carbonic oxide gases which are disengaged; and there remains in the
retort some charcoal mixed with metallic copper. These two combustibles
are in such a state of division, that the residuum is pyrophoric. Hence
it often takes fire the moment of its being removed from the cold
retort. The very considerable loss experienced in this operation has
induced chemists to try different methods to obtain all the acid
contained in the acetate. Thus, for example, a certain addition of
sulphuric acid has been prescribed; but, besides that the radical
vinegar obtained in this way always contains sulphurous acid, from which
it is difficult to free it, it is thereby deprived of that spirit called
the _pyro-acetic_, which tempers the sharpness of its smell, and gives
it an agreeable aroma. It is to be presumed, therefore, that the
preceding process will continue to be preferred for making aromatic
vinegar. Its odour is often further modified by essential oils, such as
those of rosemary, lavender, &c.

4. _Pyrolignous Acid, or Wood Vinegar._--The process for making this
acid is founded upon the general property of heat, to separate the
elements of vegetable substances, and to unite them anew in another
order, with the production of compounds which did not exist in the
bodies subjected to its action. The respective proportion of these
products varies, not only in the different substances, but also in the
same substance, according as the degree of heat has been greater or
less, or conducted with more or less skill. When we distil a vegetable
body in a close vessel, we obtain at first the included water, or that
of vegetation; there is next formed another portion of water, at the
expense of the oxygen and hydrogen of the body; a proportional quantity
of charcoal is set free, and, with the successive increase of the heat,
a small portion of charcoal combines with the oxygen and hydrogen to
form acetic acid. This was considered, for some time, as a peculiar
acid, and was accordingly called _pyrolignous_ acid. As the proportion
of carbon becomes preponderant, it combines with the other principles,
and then some empyreumatic oil is volatilised, of little colour, but
which becomes thicker, and of a darker tint, always getting more loaded
with carbon.

Several elastic fluids accompany these different products. Carbonic acid
comes over, but in small quantity, much carburetted hydrogen, and,
towards the end, a considerable proportion of carbonic oxide. The
remainder of the charcoal, which could not be carried off in these
several combinations, is found in the retort, and preserves, usually,
the form of the vegetable body which furnished it. Since mankind have
begun to reason on the different operations of the arts, and to raise
them to a level with scientific researches they have introduced into
several branches of manufacture a multitude of improvements, of which,
formerly, they would hardly have deemed them susceptible. Thus, in
particular, the process for carbonising wood has been singularly
meliorated, and in reference to the preceding observations, advantage
has been derived from several products that formerly were not even
collected.

[Illustration: _Fig._ 2.]

The apparatus employed for obtaining crude vinegar from wood, by the
agency of heat, are large iron cylinders. In this country they are made
of cast iron, and are laid horizontally in the furnace; in France, they
are made of sheet iron riveted together, and they are set upright in the
fire. _Fig._ 2. will give an accurate idea of the British plan, which is
much the same as that adopted for decomposing pit coal in gas works,
only that the cylinders for the pyrolignous acid manufacture are
generally larger, being frequently 4 feet in diameter, and 6 or 8 feet
long, and built horizontally in brickwork, so that the flame of one
furnace may play around two of them. It would, probably, answer better,
if their size were brought nearer the dimensions of the gas-light
retorts, and if the whole system of working them were assimilated to
that of coal gas.

The following arrangement is adopted in an excellent establishment in
Glasgow, where the above large cylinders are 6 feet long, and both ends
of them project a very little beyond the brickwork. One end has a disc
or round plate of cast iron, well fitted, and firmly bolted to it, from
the centre of which disc an iron tube, about 6 inches diameter, proceeds
and enters, at a right angle, the main tube of refrigeration. The
diameter of this tube may be from 9 to 14 inches, according to the
number of cylinders. The other end of the cylinder is called the mouth
of the retort; this is closed by a disc of iron, smeared round its edge
by clay lute, and secured in its place by fir wedges. The charge of wood
for such a cylinder is about 8 cwt. The hard woods--oak, ash, birch, and
beech--are alone used; fir does not answer. The heat is kept up during
the day-time, and the furnace is allowed to cool during the night. Next
morning, the door is opened, the charcoal removed, and a new charge of
wood is introduced. The average product of crude vinegar called
pyrolignous acid, is 35 gallons. It is much contaminated with tar, is of
a deep brown colour, and has a sp. gr. of 1·025. Its total weight is
therefore about 300 lbs., but the residuary charcoal is found to weigh
no more than one fifth of the wood employed; hence nearly one half of
the ponderable matter of the wood is dissipated in incondensable gases.
Count Rumford states, that the charcoal is equal in weight to more than
four tenths of the wood from which it is made. The count’s error seems
to have arisen from the slight heat of an oven to which his wood was
exposed in a glass cylinder. The result now given, is the experience of
an eminent manufacturing chemist.

The crude pyrolignous acid is rectified by a second distillation in a
copper still, in the body of which about 20 gallons of viscid tarry
matter are left from every 100. It has now become a transparent brown
vinegar, having a considerably empyreumatic smell, and a sp. gr. of
1·013. Its acid powers are superior to those of the best household
vinegar, in the proportion of three to two. By redistillation,
saturation with quicklime, evaporation of the liquid acetate to dryness,
and conversion into acetate of soda by sulphate of soda, the
empyreumatic matter is so completely dissipated, that on decomposing the
pure acetate of soda by sulphuric acid, a perfectly colourless and
grateful vinegar rises in distillation. Its strength will be
proportionable to the concentration of the decomposing acid.

The acetic acid of the chemist may be prepared also in the following
modes:--1. Two parts of fused acetate of potash, with one of the
strongest oil of vitriol, yield, by slow distillation from a glass
retort into a refrigerated receiver, concentrated acetic acid. A small
portion of sulphurous acid, which contaminates it, may be removed by
redistillation from a little acetate of lead. 2. Or four parts of good
sugar of lead, with one part of sulphuric acid, treated in the same way,
afford a slightly weaker acetic acid. 3. Gently calcined sulphate of
iron, or green vitriol, mixed with sugar of lead, in the proportion of 1
of the former to 2-1/2 of the latter, or with acetate of copper, and
carefully distilled from a porcelain retort into a cool receiver, may be
also considered an economical process. But that with binacetate of
copper above described, is preferable to any of these.

[Illustration: _Fig._ 3.]

The manufacture of pyrolignous acid is conducted in the following way in
France. Into large cylindrical vessels (_fig._ 3.) made of rivetted
sheet iron, and having at their top and side a small sheet iron
cylinder, the wood intended for making charcoal is introduced. To the
upper part of this vessel a cover of sheet iron, B, is adapted, which is
fixed with bolts. This vessel, thus closed, represents, as we see, a
vast retort. When it is prepared, as we have said, it is lifted by means
of a swing crane, C, and placed in a furnace, D, (_fig._ 4.) of a form
relative to that of the vessel, and the opening of the furnace is
covered with a dome, E, made of masonry or brickwork. The whole being
thus arranged, heat is applied in the furnace at the bottom. The
moisture of the wood is first dissipated, but by degrees the liquor
ceases to be transparent, and becomes sooty. An adopter tube, A, is then
fitted to the lateral cylinder. This adopter enters into another tube at
the same degree of inclination which commences the condensing apparatus.
The means of condensation vary according to the localities. In certain
works they cool by means of air, by making the vapour pass through a
long series of cylinders, or sometimes, even, through a series of casks
connected together; but most usually water is used for condensing, when
it can be easily procured in abundance. The most simple apparatus
employed for this purpose consists of two cylinders, F, F, (_fig._ 4.)
the one within the other, and which leave between them a sufficient
space to allow a considerable body of water to circulate along and cool
the vapours. This double cylinder is adapted to the distilling vessel,
and placed at a certain inclination. To the first double tube, F, F, a
second, and sometimes a third, entirely similar, are connected, which,
to save space, return upon themselves in a zigzag fashion. The water is
set in circulation by an ingenious means now adopted in many different
manufactories. From the lower extremity, G, of the system of condensers,
a perpendicular tube rises, whose length should be a little more than
the most elevated point of the system. The water, furnished by a
reservoir, L, enters by means of the perpendicular tube through the
lower part of the system, and fills the whole space between the double
cylinders. When the apparatus is in action, the vapours, as they
condense, raise the temperature of the water, which, by the column in L
G, is pressed to the upper part of the cylinders, and runs over by the
spout K. To this point a very short tube is attached, which is bent
towards the ground, and serves as an overflow.

[Illustration: _Fig._ 4.]

The condensing apparatus is terminated by a conduit in bricks covered
and sunk in the ground. At the extremity of this species of gutter is a
bent tube, E, which discharges the liquid product into the first
cistern. When it is full, it empties itself, by means of an overflow
pipe, into a great reservoir; the tube which terminates the gutter
plunges into the liquid, and thus intercepts communication with the
inside of the apparatus. The disengaged gas is brought back by means of
pipes M L, from one of the sides of the conduit to the under part of the
ash pit of the furnace. These pipes are furnished with stopcocks M, at
some distance in front of the furnace, for the purpose of regulating the
jet of the gas, and interrupting, at pleasure, communication with the
inside of the apparatus. The part of the pipes which terminates in the
furnace rises perpendicularly several inches above the ground, and is
expanded like the rose of a watering can, N. The gas, by means of this
disposition, can distribute itself uniformly under the vessel, without
suffering the pipe which conducts it to be obstructed by the fuel or the
ashes.

The temperature necessary to effect the carbonisation is not
considerable: however, at the last it is raised so high as to make the
vessels red hot; and the duration of the process is necessarily
proportional to the quantity of wood carbonised. For a vessel which
shall contain about 5 meters cube (nearly 6 cubic yds.), 8 hours of fire
is sufficient. It is known that the carbonisation is complete by the
colour of the flame of the gas: it is first of a yellowish red; it
becomes afterwards blue, when more carbonic oxide than carbonic hydrogen
is evolved; and towards the end it becomes entirely white,--a
circumstance owing, probably, to the furnace being more heated at this
period, and the combustion being more complete. There is still another
means of knowing the state of the process, to which recourse is more
frequently had; that is the cooling of the first tubes, which are not
surrounded with water: a few drops of this fluid are thrown upon their
surface, and if they evaporate quietly, it is judged that the
calcination is sufficient. The adopter tube is then unluted, and is slid
into its junction pipe; the orifices are immediately stopped with plates
of iron and plaster loam. The brick cover, E, of the furnace is first
removed by means of the swing crane, then the cylinder itself is lifted
out and replaced immediately by another one previously charged. When the
cylinder which has been taken out of the furnace is entirely cooled, its
cover is removed, and the charcoal is emptied. Five cubic meters of wood
furnish about 7 chaldrons (voies) and a half of charcoal. (For
modifications of the wood-vinegar apparatus, see CHARCOAL and
PYROLIGNOUS ACID.)

The different qualities of wood employed in this operation give nearly
similar product in reference to the acid; but this is not the case with
the charcoal, for it is better the harder the wood; and it has been
remarked, that wood long exposed to the air furnishes a charcoal of a
worse quality than wood carbonised soon after it is cut.

Having described the kind of apparatus employed to obtain pyrolignous
acid, I shall now detail the best mode of purifying it. This acid has a
reddish brown colour; it holds in solution a portion of empyreumatic oil
and of the tar which were formed at the same time; another portion of
these products is in the state of a simple mixture; the latter may be
separated by repose alone. It is stated, above, that the distilling
apparatus terminates in a subterranean reservoir, where the products of
all the vessels are mixed. A common pump communicates with the
reservoir, and sinks to its very bottom, in order that it may draw off
only the stratum of tar, which, according to its greater density,
occupies the lower part. From time to time the pump is worked to remove
the tar as it is deposited. The reservoir has at its top an overflow
pipe, which discharges the clearest acid into a cistern, from which it
is taken by means of a second pump.

The pyrolignous acid thus separated from the undissolved tar is
transferred from this cistern into large sheet iron boilers, where its
saturation is effected either by quicklime or by chalk; the latter of
which is preferable, as the lime is apt to take some of the tar into
combination. The acid parts by saturation with a new portion of the tar,
which is removed by skimmers. The neutral solution is then allowed to
rest for a sufficient time to let its clear parts be drawn off by
decantation.

The acetate of lime thus obtained indicates by the hydrometer, before
being mixed with the waters of edulcoration, a degree corresponding to
the acidimetric degree of the acid employed. This solution must be
evaporated till it reaches a specific gravity of 1·114 (15° Baumé),
after which there is added to it a saturated solution of sulphate of
soda. The acids exchange bases; sulphate of lime precipitates, and
acetate of soda remains in solution. In some manufactures, instead of
pursuing the above plan, the sulphate of soda is dissolved in the hot
pyrolignous acid, which is afterwards saturated with chalk or lime. By
this means no water need be employed to dissolve the sulphate, and
accordingly the liquor is obtained in a concentrated form without
evaporation. In both modes the sulphate of lime is allowed to settle,
and the solution of acetate of soda is decanted. The residuum is set
aside to be edulcorated, and the last waters are employed for washing
fresh portions.

The acetate of soda which results from this double decomposition is
afterwards evaporated till it attains to the density of 1·225 or 1·23,
according to the season. This solution is poured into large
crystallising vessels, from which, at the end of 3 or 4 days, according
to their capacity, the mother waters are decanted, and a first
crystallisation is obtained of rhomboidal prisms, which are highly
coloured and very bulky. Their facettes are finely polished, and their
edges very sharp. The mother waters are submitted to successive
evaporations and crystallisations till they refuse to crystallise, and
they are then burnt to convert them into carbonate of soda.

To avoid guesswork proportions, which are always injurious, by the loss
of time which they occasion, and by the bad results to which they often
lead, we should determine experimentally, beforehand, the quantities
absolutely necessary for the reciprocal decomposition, especially when
we change the acid or the sulphate. But it may be remarked that,
notwithstanding all the precautions we can take, there is always a
notable quantity of sulphate of soda and acetic acid, which disappear
totally in this decomposition. This arises from the circumstance that
sulphate of soda and acetate of lime do not completely decompose each
other, as I have ascertained by experiments on a very considerable
scale; and thus a portion of each of them is always lost with the mother
waters. It might be supposed that by calcining the acetate of lime we
could completely destroy its empyreumatic oil; but, though I have made
many experiments, with this view I never could obtain an acetate capable
of affording a tolerable acid. Some manufacturers prefer to make the
acetate of soda by direct saturation of the acid with the alkali, and
think that the higher price of this substance is compensated by the
economy of time and fuel which it produces.

The acetate of soda is easily purified by crystallisations and
torrefaction; the latter process, when well conducted, freeing it
completely from every particle of tar. This torrefaction, to which the
name of fusion may be given, requires great care and dexterity. It is
usually done in shallow cast iron boilers of a hemispherical shape.
During all the time that the heat of about 500° Fahr. is applied, the
fused mass must be diligently worked with rakes; an operation which
continues about 24 hours for half a ton of materials. We must carefully
avoid raising the temperature so high as to decompose the acetate, and
be sure that the heat is equally distributed; for if any point of the
mass enters into decomposition, it is propagated with such rapidity, as
to be excessively difficult to stop its progress in destroying the
whole. The heat should never be so great as to disengage any smoke, even
when the whole acetate is liquefied. When there is no more frothing up,
and the mass flows like oil, the operation is finished. It is now
allowed to cool in a body, or it may be ladled out into moulds, which is
preferable.

When the acetate is dissolved in water, the charcoaly matter proceeding
from the decomposition of the tar must be separated by filtration, or by
boiling up the liquor to the specific gravity 1·114, when the
carbonaceous matter falls to the bottom. On evaporating the clear
liquor, we obtain an acetate perfectly fine, which yields beautiful
crystals on cooling. In this state of purity it is decomposed by
sulphuric acid, in order to separate its acetic acid.

This last operation, however simple it appears, requires no little care
and skill. The acetate of soda crystallised and ground is put into a
copper, and the necessary quantity of sulphuric acid of 1·842 (about 35
per cent. of the salt) to decompose almost, but not all, the acetate, is
poured on. The materials are left to act on each other; by degrees the
acetic acid quits its combination, and swims upon the surface; the
greater part of the resulting sulphate of soda falls in a pulverulent
form, or in small granular crystals, to the bottom. Another portion
remains dissolved in the liquid, which has a specific gravity of 1·08.
By distillation we separate this remainder of the sulphate, and finally
obtain acetic acid, having a specific gravity of 1·05, an agreeable
taste and smell, though towards the end it becomes a little
empyreumatic, and coloured; for which reason, the last portions must be
kept apart. The acid destined for table use ought to be distilled in an
alembic whose capital and condensing worm are of silver; and to make it
very fine, it may be afterwards infused over a little washed bone-black.
It is usually obtained in a pretty concentrated state; but when we wish
to give it the highest degree of concentration, we mix with it a
quantity of dry muriate of lime, and distil anew. This acid may be
afterwards exposed to congelation, when the strongest will crystallise.
It is decanted, and the crystals are melted by exposing them to a
temperature of from 60° to 70° Fahr.; this process is repeated till the
acid congeals without remainder, at the temperature of 55° Fahr. It has
then attained its maximum strength, and has a specific gravity of 1·063.

We shall add an observation on the above mode of decomposing the acetate
of soda by sulphuric acid. Many difficulties are experienced in this
process, if the sulphuric acid be poured on in small quantities at a
time; for then such acrid fumes of acetic acid are disengaged, that the
workmen are obliged to retire. This inconvenience may be saved by adding
all the sulphuric acid at once; it occupies the lower part of the
vessel, and decomposes only the portion of the acetate in contact with
it; the heat evolved in consequence of this reaction is diffused through
a great mass, and produces no sensible effect. When the sulphuric acid
forms an opening, or a species of little crater, the workman, by means
of a rake, depresses the acetate into it by degrees, and then the
decomposition proceeds as slowly as he desires.

The acetic acid, like the nitric, chloric, and some others, has not
hitherto been obtained free from water, and the greatest degree of
concentration which we have been able to give it is that in which it
contains only the quantity of water equivalent to the atomic weight of
another oxidized body; a quantity which amounts to 14·89 per cent. The
processes prescribed for preparing concentrated acetic acid sometimes
tend to deprive it of that water without which it could not exist:
hence, in all such cases, there is a part of the acid itself decomposed
to furnish the water necessary to the constitution of the remainder. The
constituent principles of the decomposed portion then form a peculiar,
intoxicating, highly inflammatory liquid, called the PYRO-ACETIC SPIRIT.

The most highly concentrated acid of 1·063 becomes denser by the
addition of a certain quantity of water up to a certain point. According
to Berzelius, the prime equivalent of this acid is 643·189, oxygen being
reckoned 100. Now, the above strongest acid consists of one prime of
acid, and one of water = 1124·79. When it contains three atoms of water,
that is, 337·437 parts to 643·189, or 34·41 to 65·59 in 100, it then has
taken its maximum density of 1·075; after which the further addition of
water diminishes its specific gravity, as the following table of
Mollerat shows. His supposed anhydrous or dry acid contains, at 1·0630,
0·114 parts of water.

_Table of Acetic Acid._

  +----------+--------+
  | Water in |Specific|
  |100 parts.|gravity.|
  +----------+--------+
  |   0·00   | 1·0630 |
  |   8·37   | 1·0742 |
  |  17·00   | 1·0770 |
  |  23·00   | 1·0791 |
  |  28·10   | 1·0763 |
  |  33·83   | 1·0742 |
  |  37·60   | 1·0728 |
  |  47·00   | 1·0658 |
  |  50·00   | 1·0637 |
  |  51·80   | 1·063  |
  +----------+--------+

Acetic acid readily takes fire when it is heated in open vessels to the
boiling point, and it burns with a blue flame, nearly like alcohol. It
must be kept in close vessels, otherwise it loses its strength, by
attracting humidity from the air. When concentrated, it is used only as
a scent, or pungent exciter of the olfactory organs, in sickness and
fainting fits. Its anti-epidemic qualities are apocryphal. What is met
with in the shops under the name of salts of vinegar is nothing but
sulphate of potash, put up in small phials, and impregnated with acetic
acid, sometimes rendered aromatic with oil of rosemary or lavender.

Acetic acid, in its dry state, as it exists in fused acetate of potash
or soda, is composed of

   47·536 carbon
    5·822 hydrogen
   46·642 oxygen
  -------
  100·000

And its symbol by Berzelius is H⁶ C⁴ O³ = A. We must bear in mind that
his atomic weight for hydrogen is only one half of the number usually
assigned to it by British chemists, in consequence of his making water a
compound of two atoms of hydrogen and one of oxygen.

When the vapour of acetic acid is made to traverse a red-hot tube of
iron, it is converted into water, carbonic acid, carburetted hydrogen,
but chiefly pyro-acetic spirit. Acetic acid is a solvent of several
organic products; such as camphor, gluten, gum-resins, resins, the
fibrine of blood, the white of egg, &c.

It is an important problem to ascertain the purity and strength of
vinegar. Spurious acidity is too often given to it by cheaper acids,
such as the sulphuric and the nitric. The former, may most surely be
detected by the nitrate of baryta, or even by acetate of lead, which
occasion a white precipitate in such adulterated vinegar. For the case
of nitric, which is more insidious, the proper test is, a bit of gold
leaf, wetted with a few drops of muriatic acid. If the leaf dissolves,
on heating the mixture in a watch glass, we may be sure that nitric acid
is present.

Specific gravity, if determined by a sensible hydrometer, is a good test
of the strength of the genuine vinegar; and the following table of
Messrs. Taylor is nearly correct, or sufficiently so for commercial
transactions.

Revenue proof vinegar, called by the English manufacturer No. 24., has a
specific gravity of

  1·0085 and contains of real acid in 100--  5
  1·0170                                    10
  1·0257                                    15
  1·0320                                    20
  1·0470                                    30
  1·0580                                    40

An excise duty of 2_d._ is levied on every gallon of the above proof
vinegar. Its strength is not, however, estimated directly by its
specific gravity, but by the specific gravity which it assumes when
saturated with quicklime. The decimal fraction of the specific gravity
of the calcareous acetate is very nearly the double of that of the pure
vinegar; or, 1·009 in vinegar becomes 1·018 in acetate of lime. The
vinegar of malt contains so much mucilage or gluten, that when it has
only the same acid strength as the above, it has a density of 1·0014,
but it becomes only 1·023 when converted into acetate of lime: indeed,
0·005 of its density is due to mucilaginous matter. This fact shows the
fallacy of trusting to the hydrometer for determining the strength of
vinegars, which may be more or less loaded with vegetable gluten. The
proper test of this, as of all other acids, is, the quantity of alkaline
matter which a given weight or measure of it will saturate. For this
purpose the bicarbonate of potash, commonly called, in the London shops,
carbonate, may be employed very conveniently. As it is a very uniform
substance, and its atomic weight, by the hydrogen radix, is 100·584,
while the atomic weight of acetic acid, by the same radix, is 51·563, if
we estimate 2 grains of the bicarbonate as equivalent to 1 of the real
acid, we shall commit no appreciable error. Hence, a solution of the
carbonate containing 200 grains in 100 measures, will form an acetimeter
of the most perfect and convenient kind; for the measures of test liquid
expended in saturating any measure,--for instance, an ounce or 1000
grains of acid,--will indicate the number of grains of real acetic acid
in that quantity. Thus, 1000 grains of the above proof, would require 50
measures of the acetimetrical alkaline solution, showing that it
contains 50 grains of real acetic acid in 1000, or 5 per cent.

It is common to add to purified wood vinegar, a little acetic ether, or
caramelised (burnt) sugar to colour it, also, in France, even wine, to
flavour it. Its blanching effect upon red cabbage, which it has been
employed to pickle, is owing to a little sulphurous acid. This may be
removed by redistillation with peroxide of manganese. Indeed, Stoltze
professes to purify the pyrolignous acid solely by distilling it with
peroxide of manganese, and then digesting it with bruised wood charcoal;
or by distilling it with a mixture of sulphuric acid and manganese. But
much acid is lost in this case by the formation of acetate of that
metal.

Birch and beech afford most Pyrolignous acid, and pine the least. It is
exclusively employed in the arts, for most purposes of which it need not
be very highly purified. It is much used in calico printing, for
preparing acetate of iron called IRON LIQUOR, and acetate of alumina,
called RED LIQUOR; which see. It serves also to make sugar of lead; yet
when it contains its usual quantity, after rectification, of tarry
matter, the acetate of lead will hardly crystallise, but forms
cauliflower concretions. This evil may be remedied, I believe, by
boiling the saline solution with a very little nitric acid, which causes
the precipitation of a brown granular substance, and gives the liquor a
reddish tinge. The solution being afterwards treated with bruised
charcoal, becomes colourless, and furnishes regular crystals of acetate
or sugar of lead.

Pyrolignous acid possesses, in a very eminent degree, anti-putrescent
properties. Flesh steeped in it for a few hours may be afterwards dried
in the air without corrupting; but it becomes hard, and somewhat
leather-like: so that this mode of preservation does not answer well for
butcher’s meat. Fish are sometimes cured with it. See PYRO-ACETIC
SPIRIT; PYROXILIC ETHER; PYROXOLIC SPIRIT; PYROLIGNOUS ACID and
VINEGAR.


ACETIMETER. An apparatus for determining the strength of vinegar. See
the conclusion of the preceding article for a description of my simple
method of acetimetry.


ACETONE. The new chemical name of pyro-acetic spirit.


ACID OF ARSENIC. (_Acide Arsenique_, Fr.; _Arseniksäure_, Germ.)


ACIDS. A class of chemical substances characterised by the property of
combining with and neutralising the alkaline and other bases, and of
thereby forming a peculiar class of bodies called salts. The acids which
constitute objects of special manufacture for commercial purposes are
the following:--acetic, arsenious, carbonic, chromic, citric, malic,
muriatic, nitric, oxalic, phosphoric, sulphuric, tartaric, which see.


ACROSPIRE. (_Plumule_, Fr.; _Blattkeim_, Germ.) That part of a
germinating seed which botanists call the plumula, or plumes. See BEER
and MALT.


ADDITIONS. Such articles as are added to the fermenting wash of the
distiller are distinguished by this trivial name.


ADIPOCIRE. Fr. (_Fettwachs_, Germ.) The fatty matter generated in dead
bodies buried under peculiar circumstances. In 1786 and 1787, when the
churchyard of the _Innocents_, at Paris, was cleaned out, and the bones
transported to the catacombs, it was discovered that not a few of the
_cadavres_ were converted into a saponaceous white substance, more
especially many of those which had been interred for fifteen years in
one pit, to the amount of 1500, in coffins closely packed together.
These bodies were flattened, in consequence of their mutual pressure;
and, though they generally retained their shape, there was deposited
round the bones of several a grayish white, somewhat soft, flexible
substance. Fourcroy presented to the Academy of Sciences, in 1789, a
comprehensive memoir upon this phenomenon, which appeared to prove that
the fatty body was an ammoniacal soap, containing phosphate of lime;
that the fat was similar to spermaceti, as it assumed on slow cooling a
foliated crystalline structure; as also to wax, as, when rapidly cooled,
it became granular: hence he called it _Adipocire_. Its melting point
was 52·5° C. (126·5° Fahr.). He likewise compared this soap to the fat
of gall-stones, and supposed it to be a natural product of the slow
decomposition of all animal matter, except bones, nails, and hairs.

This substance was again examined by Chevreul in 1812, and was found by
him to contain margaric acid, oleic acid, combined with a yellow
colouring, odorous matter, besides ammonia, a little lime, potash, oxide
of iron, salts of lactic acid, an azotized substance; and was therefore
considered as a combination of margaric and oleic acids, in variable
proportions (whence arose its variable fusibility), but that it was not
analogous with either spermaceti or cholesterine (gallstones). These fat
acids are obviously generated by the reaction of the ammonia upon the
margarine and oleine, though they eventually lose the greater part of
that volatile alkali.

According to the views of both Gay Lussac and Chevreul, this _adipocire_
proceeds solely from the pre-existing fat of the dead body, and not from
the flesh, tendons, or cartilages, as had been previously imagined;
which had led to some expensive and abortive attempts, upon the great
scale of manufacture, to convert the dead bodies of cattle into
adipocire, for the purposes of the candle-maker or soap-boiler, by
exposing them for some time to the action of moisture.

Von Hartkol made experiments during 25 years upon this subject, from
which he inferred, that there is no formation of adipocire in bodies
buried in dry ground; that in moist earth the fat of the dead body does
not increase, but changes into a fetid saponaceous substance, incapable
of being worked into either soap or candles; that the dead bodies of
_mammalia_ immersed in running water, leave behind after 3 years a pure
fat, which is more abundant from young than from old animals; that the
intestines afford more fat than the muscles; that from this fat, without
any purification, candles may be made, as void of smell, as hard, and as
white, as from bleached wax; that from cadavers immersed for 3 years in
stagnant water, more fat is procured than from those in running water,
but that it needs to be purified before it can be made into soap or
candles.

The cause of the difference between Hartkol’s and Chevreul’s results
cannot be assigned, as the latter has not published his promised remarks
upon the subject. At any rate, dead animal matter can be worked up more
profitably than in making artificial _adipocire_.


ADIT. The horizontal entrance of a mine. It is sometimes called the
drift. See MINING and METALLURGY.


ADULTERATION. The debasing any product of manufacture, especially
chemical, by the introduction of cheap materials. The art of
ascertaining the genuineness of the several products will be taught
under the specific objects of manufacture.


ÆTHER. See ETHER.


AFFINITY. The chemical term denoting the peculiar attractive force which
produces the combination of dissimilar substances; such as of an alkali
with an acid, or of sulphur with a metal.


AGARIC. A species of boletus or fungus, which grows in dunghills; with
the salts of iron it affords a black dye. It is said to be convertible
into a kind of china ink.


AGATE. A siliceous mineral which is cut into seals and other forms for
the coarser kinds of jewellery. See GEM.


AIR. See VENTILATION.


ALABASTER, is a stone usually white, and soft enough to be scratched by
iron. There are two kinds of it: the gypseous, which is merely a natural
semi-crystalline sulphate of lime; and the calcareous alabaster, which
is a carbonate of lime. The oriental alabaster is always of the latter
kind, and is most esteemed, because it is agreeably variegated with
lively colours, and especially with zones of honey-yellow, yellow-brown,
red, &c.; it is, moreover, susceptible of taking a marble polish.

The fineness of the grain of alabaster, the uniformity of its texture,
the beauty of its polished surface, and its semi-transparency, are the
qualities which render it valuable to the sculptor and to the
manufacturer of ornamental toys.

The limestone alabaster is frequently found as a yellowish-white deposit
in certain fountains. The most celebrated spring of this kind is that of
the baths of San Filippo, in Tuscany. The water, almost boiling hot,
runs over an enormous mass of stalactites, which it has formed, and
holds the carbonate of lime in solution by means of sulphuretted
hydrogen (according to M. Alexandre Brongniart), which escapes by
contact of the atmosphere. Advantage has been taken of this property to
make _basso relievos_ of considerable hardness, by placing moulds of
sulphur very obliquely, or almost upright, in wooden tubs open at the
bottom. These tubs are surmounted at the top with a large wooden cross.
The water of the spring, after having deposited in an external conduit
or cistern the coarser sediment, is made to flow upon this wooden cross,
where it is scattered into little streamlets, and thence lets fall, upon
the sulphur casts, a precipitate so much the finer the more nearly
vertical the mould. From one to four months are required for this
operation, according to the thickness of the deposited crust. By
analogous processes, the artists have succeeded in moulding vases,
figures of animals, and other objects, in relief, of every different
form, which require only to be trimmed a little, and afterwards
polished.

The common alabaster is composed of sulphuric acid and lime, though some
kinds of it effervesce with acids, and therefore contain some carbonate
of lime. This alabaster occurs in many different colours, and of very
different degrees of hardness, but it is always softer than marble. It
forms, usually, the lowest beds of the gypsum quarries. The sculptors
prefer the hardest, the whitest, and those of a granular texture, like
Carrara marble, and so like that they can only be distinguished by the
hardness.

The alabaster is worked with the same tools as marble; and as it is many
degrees softer, it is so much the more easily cut; but it is more
difficult to polish, from its little solidity. After it has been
fashioned into the desired form, and smoothed down with pumice stone, it
is polished with a pap-like mixture of chalk, soap, and milk; and, last
of all, finished by friction with flannel. It is apt to acquire a
yellowish tinge.

Besides the harder kinds, employed for the sculpture of large figures,
there is a softer alabaster, pure white and semi-transparent, from which
small ornamental objects are made, such as boxes, vases, lamps, stands
of time-pieces, &c. This branch of business is much prosecuted in
Florence, Leghorn, Milan, &c., and employs a great many turning lathes.
Of all the alabasters the Florentine merits the preference, on account
of its beauty and uniformity, so that it may be fashioned into figures
of considerable size; for which purpose there are large work-shops where
it is cut with steel saws into blocks and masses of various shapes.
Other sorts of gypsum, such as that of Salzburg and Austria, contain
sand veins, and hard nodules, and require to be quarried by cleaving and
blasting operations, which are apt to crack it, and unfit it for all
delicate objects of sculpture. It is, besides, of a gray shade, and
often stained with darker colours.

The alabaster best adapted for the fine arts is pretty white when newly
broken, and becomes whiter on the surface by drying. It may be easily
cut with the knife or chisel, and formed into many pleasing shapes by
suitable steel tools. It is worked either by the hand alone, or with the
aid of a turning lathe. The turning tools should not be too thin or
sharp-edged; but such as are employed for ivory and brass are most
suitable for alabaster, and are chiefly used to shave and to scratch the
surface. The objects which cannot be turned may be fashioned by the
rasping tools, or with minute files, such as variegated foliage. Fine
chisels and graving tools are also used for the better pieces of
statuary.

For polishing such works, a peculiar process is required: pumice stone,
in fine powder, serves to smooth down the surfaces very well, but it
soils the whiteness of the alabaster. To take away the unevennesses and
roughnesses dried shave-grass (_equisetum_) answers best. Frictions with
this plant and water polish down the asperities left by the chisel: the
fine streaks left by the grass may be removed by rubbing the pieces with
slaked lime, finely pulverised and sifted, made into a paste, or putty,
with water. The polish and satin-lustre of the surface are communicated
by friction, first with soap-water and lime, and finally with powdered
and elutriated talc or French chalk.

Such articles as consist of several pieces are joined by a cement
composed of quicklime and white of egg, or of well-calcined and
well-sifted Paris plaster, mixed with the least possible quantity of
water.

Alabaster objects are liable to become yellow by keeping, and are
especially injured by smoke, dust, &c. They may be in some measure
restored by washing with soap and water, then with clear water, and
again polished with shave-grass. Grease spots may be removed either by
rubbing with talc powder, or with oil of turpentine.

The surface of alabaster may be etched by covering over the parts that
are not to be touched with a solution of wax in oil of turpentine,
thickened with white lead, and immersing the articles in pure water
after the varnish has set. The action of the water is continued from 20
to 50 hours, more or less, according to the depth to which the etching
is to be cut. After removing the varnish with oil of turpentine, the
etched places, which are necessarily deprived of their polish, should be
rubbed with a brush dipped in finely-powdered gypsum, which gives a kind
of opacity, contrasting well with the rest of the surface.

Alabaster may be stained either with metallic solutions, with spirituous
tinctures of dyeing plants, or with coloured oils, in the same way as
marbles.

This substance has been hardened, it is said, by exposing it to the heat
of a baker’s oven for 10 or 20 hours, after taking it out of the quarry,
and giving it the figure, roughly, which it is intended to have. After
this exposure, it must be dipped for two minutes in running water; when
it is cold, it must be dipped a second time for the same period. On
being exposed to the air for a few days, alabaster so treated acquires a
marble-like hardness. I doubt the truth of this statement.


ALBUM GRÆCUM. The white dung of dogs, sometimes used to soften leather
in the process of dressing it after the depilatory action of lime.


ALCARAZZAS. A species of porous earthenware, made in Spain, for cooling
liquors. See POTTERY.


ALCOHOL. The well-known intoxicating liquor procured by distillation
from various vegetable juices, and infusions of a saccharine nature,
which have undergone the vinous fermentation. Common alcohol, or proof
spirit, as it is called, contains about one half its weight of water. It
may be concentrated till its specific gravity becomes so low as 0·825,
by simple redistillation at a steam or water-bath heat; but to make it
stronger, we must mix with it, in the still or retort, dry carbonate of
potash, muriate of lime, or some other substances strongly attractive of
water, and then it may be obtained of a specific gravity so low as 0·791
at 16° Reaumur (68° Fahr.), water being 1·000. At 0·825, it contains,
still, 11 per cent. of water; and in this state it is as volatile as
absolute alcohol, on account of the inferior density of the aqueous
vapour, compared to the alcoholic. Indeed, according to Yelin and Fuchs,
the boiling point of anhydrous alcohol is higher than of that which
contains 2 or 3 per cent. of water; hence, in the distillation of
alcohol of 94 per cent., the first portions that come over are more
aqueous than the following. Absolute alcohol has its boiling point at
168-1/2° Fahr.: but when it holds more than 6 per cent. of water, the
first portions that come over are richest in alcohol, and the
temperature of the boiling point, or of the spirituous vapour, is always
higher the longer the distillation continues. According to Gröning’s
researches, the following temperatures of the alcoholic vapours
correspond to the accompanying contents of alcohol in per centage of
volume, which are disengaged in the boiling of the spirituous liquid.

  +------------+-----------+-----------+
  |            |Alcoholic  |Alcoholic  |
  |Temperature.|content of |content of |
  |            |the vapour.|the boiling|
  |            |           |liquid.    |
  +------------+-----------+-----------+
  |Fahr. 170·0 |   93      |    92     |
  |      171·8 |   92      |    90     |
  |      172   |   91      |    85     |
  |      172·8 |   90-1/2  |    80     |
  |      174   |   90      |    70     |
  |      174·6 |   89      |    70     |
  |      176   |   87      |    65     |
  |      178·3 |   85      |    50     |
  |      180·8 |   82      |    40     |
  |      183   |   80      |    35     |
  |      185   |   78      |    30     |
  |      187·4 |   76      |    25     |
  |      189·8 |   71      |    20     |
  |      192·0 |   68      |    18     |
  |      164   |   66      |    15     |
  |      196·4 |   61      |    12     |
  |      198·6 |   55      |    10     |
  |      201   |   50      |     7     |
  |      203   |   42      |     5     |
  |      205·4 |   36      |     3     |
  |      207·7 |   28      |     2     |
  |      210   |   13      |     1     |
  |      212   |    0      |     0     |
  +------------+-----------+-----------+

Gröning undertook this investigation in order to employ the thermometer
as an alcoholmeter in the distillation of spirits; for which purpose he
thrust the bulb of the thermometer through a cork, inserted into a tube
fixed in the capital of the still. The state of the barometer ought also
to be considered in making comparative experiments of this kind. Since,
by this method, the alcoholic content may be compared with the
temperature of the vapour that passes over at any time, so, also, the
contents of the whole distillation may be found approximately; and the
method serves as a convenient means of making continual observations on
the progress of the distillation.

The temperature, corresponding to a certain per centage of alcohol in
vapour, suggests the employment of a convenient method for obtaining, at
one process, a spirit as free from water as it can be made by mere
distillation. We place over the top of the capital a water-bath, and
lead up through it a spiral pipe from the still, which there passes
obliquely downwards, and proceeds to the refrigeratory. If this bath be
maintained, by a constant influx of cold water, at a certain
temperature, only the alcoholic vapour corresponding to that temperature
will pass over, and the rest will be recondensed and returned into the
still. If we keep the temperature of the water at 174°, for example, the
spirituous vapour which passes over will contain 90 per cent. of
absolute alcohol, according to the preceding table. The skilful use of
this principle constitutes the main improvement in modern distilleries.
See DISTILLATION and STILL.

Another method for concentrating alcohol is that discovered by
Sömmering, founded upon the property of ox bladders to allow water to
pass through and evaporate out of them, but not to permit alcohol to
transpire, or only in a slight degree. Hence, if an ox’s bladder is
filled with spirit of wine, well tied at the mouth, and suspended in a
warm place, the water will continually exhale, and the alcohol will
become nearly anhydrous; for in this way alcohol of 97 or 98 per cent.
may be obtained.

According to Sömmering, we should take for this purpose the bladder of
an ox or a calf, soak it for some time in water, then inflate it and
free it from the fat and the attached vessels; which is to be also done
to the other surface, by turning it inside out. After it is again
inflated and dried, we must smear over the outer side twice, and the
inner side four times, with a solution of isinglass, by which its
texture is made closer, and the concentration of the alcohol goes on
better. A bladder so prepared may serve more than a hundred times. It
must be charged with the spirits to be concentrated, leaving a small
space vacant, it is then to be tightly bound at the mouth, and suspended
in a warm situation, at a temperature of 122° Fahr., over a sand-bath,
or in the neighbourhood of an oven. The surface of the bladder remains
moist with the water, as long as the sp. gr. of the contained spirit is
greater than 0·952. Weak spirit loses its water quicker than strong; but
in from 6 to 12 hours the alcohol may be concentrated, when a suitable
heat is employed. This economical method is particularly applicable in
obtaining alcohol for the preparation of varnishes. When the alcohol is
to serve for other purposes, it must be freed, by distillation, from
certain matters dissolved out of the bladder. Alcohol may likewise be
strengthened, as Sömmering has ascertained when the vessel that contains
the spirit is bound over with a bladder which does not come into contact
with the liquid. Thus, too, all other liquors containing alcohol and
water, as wine, cider, &c., may be made more spirituous.

To procure absolute alcohol, we must take chloride of calcium recently
fused, reduce it to coarse powder, and mix it with its own weight of
spirit of wine, of sp. gr. 0·833, in a bottle, which is to be well
stoppered, and to be agitated till the salt is dissolved. The clear
solution is to be poured into a retort, and half of the volume of the
alcohol employed, or so much as has the sp. gr. 0·791 at 68° Fahr., is
to be distilled off at a gentle heat. Quicklime has also been employed
for the same purpose, but it is less powerful and convenient. Alcohol,
nearly free from water, may be obtained without distillation, by adding
dry carbonate of potash to a spirit of wine, of sp. gr. 0·825. The water
combines with the potash, and falls to the bottom in a dense liquid,
while the pure spirit floats on the surface. This contains however a
little alkali, which can only be separated by distillation.

Anhydrous alcohol is composed by weight of 52·66 carbon, 12·90 hydrogen,
and 34·44 of oxygen. It has a very powerful attraction for water, and
absorbs it from the atmosphere; therefore it must be kept in well-closed
vessels. It also robs vegetable and animal bodies of their moisture; and
hence common alcohol is employed for preserving anatomical preparations.
Alcohol is a solvent for many substances: resins, essential oils,
camphor, are abundantly dissolved by it, forming varnishes, perfumed
spirits, &c. The solution of a resin or essential oil in alcohol becomes
milky on the addition of water, which, by its attraction for alcohol,
separates these substances. Several salts, especially the deliquescent,
are dissolved by it, and some of them give a colour to its flame; thus,
the solutions of the salts of strontia in alcohol burn with a crimson
flame, those of copper and borax green, lime reddish, and baryta yellow.

When water is mixed with alcohol, heat and a condensation of volume are
the result; these effects being greatest with 54 per cent. of alcohol
and 46 of water, and thence decreasing with a greater proportion of
water. For alcohol which contains 90 per cent. of water, this
condensation amounts to 1·94 per cent. of the volume; for 80 per cent.,
2·87; for 70 per cent., 3·44; for 60 per cent., 3·73; for 40 per cent.,
3·44; for 30 per cent., 2·72; for 20 per cent., 1·72; for 10 per cent.,
0·72. Hence, to estimate the quantity of alcohol in any spirit it is
necessary that the specific gravity be ascertained for each determinate
proportion of alcohol and water that are mixed together. When this is
done, we may, by means of an areometer constructed for liquids lighter
than water, determine the strength of the spirit, either by a scale of
specific gravities or by an arbitrary graduation corresponding to
certain commercial objects, and thus we may determine the per centage of
alcohol in whisky or brandy of any strength or purity. An areometer
intended for this use has been called an alcoholmeter, in particular
when the scale of it is so graduated that, instead of the specific
gravity, it indicates immediately the per centage of anhydrous alcohol
in a given weight or volume of the liquid. The scale graduated according
to the per centage of pure alcohol by weight, constitutes the
alcoholmeter of Richter; and that by the per centage in volume, the
alcoholmeter of Tralles and Gay Lussac.

As liquors are sold in general by the measure, not by the weight, it is
convenient, therefore, to know the alcoholic content of the mixtures in
the per centage by volume. Tralles has constructed new tables upon the
principles of those of Gilpin, in which the proportion is given by
volume, and anhydrous alcohol is assumed for the basis; which, at 60°
Fahr., has a specific gravity of 0·7939 compared with water at its
maximum density, or a specific gravity 0·7946 compared with water of the
temperature of 60° Fahr. Gilpin’s alcohol of 0·825 contains 92·6 per
cent. by volume of anhydrous alcohol.

The following table exhibits the per centage of anhydrous alcohol by
volume, at a temperature of 60° Fahr., in correspondence with the
specific gravities of the spirits, water being considered at 60° Fahr.
to have a specific gravity of 0·9991.

Alcoholmetrical Table of Tralles.

  +------------+------------+----------+
  |Alcohol in  |  Specific  |Difference|
  |100 measures|  gravity   | of the   |
  | of spirit. |at 60° Fahr.| sp. gr.  |
  +------------+------------+----------+
  |     0      |    9991    |          |
  |     1      |    9976    |    15    |
  |     2      |    9961    |    15    |
  |     3      |    9947    |    14    |
  |     4      |    9933    |    14    |
  |     5      |    9919    |    14    |
  |     6      |    9906    |    13    |
  |     7      |    9893    |    13    |
  |     8      |    9881    |    12    |
  |     9      |    9869    |    12    |
  |    10      |    9857    |    12    |
  |    11      |    9845    |    12    |
  |    12      |    9834    |    11    |
  |    13      |    9823    |    11    |
  |    14      |    9812    |    11    |
  |    15      |    9802    |    10    |
  |    16      |    9791    |    11    |
  |    17      |    9781    |    10    |
  |    18      |    9771    |    10    |
  |    19      |    9761    |    10    |
  |    20      |    9751    |    10    |
  |    21      |    9741    |    10    |
  |    22      |    9731    |    10    |
  |    23      |    9720    |    11    |
  |    24      |    9710    |    10    |
  |    25      |    9700    |    10    |
  |    26      |    9689    |    11    |
  |    27      |    9679    |    10    |
  |    28      |    9668    |    11    |
  |    29      |    9657    |    11    |
  |    30      |    9646    |    11    |
  |    31      |    9634    |    12    |
  |    32      |    9622    |    12    |
  |    33      |    9609    |    13    |
  |    34      |    9596    |    13    |
  |    35      |    9583    |    13    |
  |    36      |    9570    |    13    |
  |    37      |    9556    |    14    |
  |    38      |    9541    |    15    |
  |    39      |    9526    |    15    |
  |    40      |    9510    |    16    |
  |    41      |    9494    |    16    |
  |    42      |    9478    |    16    |
  |    43      |    9461    |    17    |
  |    44      |    9444    |    17    |
  |    45      |    9427    |    17    |
  |    46      |    9409    |    18    |
  |    47      |    9391    |    18    |
  |    48      |    9373    |    18    |
  |    49      |    9354    |    19    |
  |    50      |    9335    |    19    |
  |    51      |    9315    |    20    |
  |    52      |    9295    |    20    |
  |    53      |    9275    |    20    |
  |    54      |    9254    |    21    |
  |    55      |    9234    |    20    |
  |    56      |    9213    |    21    |
  |    57      |    9192    |    21    |
  |    58      |    9170    |    22    |
  |    59      |    9148    |    22    |
  |    60      |    9126    |    22    |
  |    61      |    9104    |    22    |
  |    62      |    9082    |    22    |
  |    63      |    9059    |    23    |
  |    64      |    9036    |    23    |
  |    65      |    9013    |    23    |
  |    66      |    8989    |    24    |
  |    67      |    8965    |    24    |
  |    68      |    8941    |    24    |
  |    69      |    8917    |    24    |
  |    70      |    8892    |    25    |
  |    71      |    8867    |    25    |
  |    72      |    8842    |    25    |
  |    73      |    8817    |    25    |
  |    74      |    8791    |    26    |
  |    75      |    8765    |    26    |
  |    76      |    8739    |    26    |
  |    77      |    8712    |    27    |
  |    78      |    8685    |    27    |
  |    79      |    8658    |    27    |
  |    80      |    8631    |    27    |
  |    81      |    8603    |    28    |
  |    82      |    8575    |    28    |
  |    83      |    8547    |    28    |
  |    84      |    8518    |    29    |
  |    85      |    8488    |    30    |
  |    86      |    8458    |    30    |
  |    87      |    8428    |    30    |
  |    88      |    8397    |    31    |
  |    89      |    8365    |    32    |
  |    90      |    8332    |    33    |
  |    91      |    8299    |    33    |
  |    92      |    8265    |    34    |
  |    93      |    8230    |    35    |
  |    94      |    8194    |    36    |
  |    95      |    8157    |    37    |
  |    96      |    8118    |    39    |
  |    97      |    8077    |    41    |
  |    98      |    8034    |    43    |
  |    99      |    7988    |    46    |
  |   100      |    7939    |    49    |
  +------------+------------+----------+

_Remarks on the preceding Table of Alcohol._

The third column of this table exhibits the differences of the specific
gravities, which give the denominator of the fraction for such densities
as are not found sufficiently near in the table; and the difference of
their numerators is the next greatest to the density found in the table.
For example: if the specific gravity of the liquor found for 60° Fahr. =
9605 (the per centage will be between 33 and 34), the difference from
9609 (which is the next greatest number in the table) = 4, and the
fraction is 4/13; therefore the true per centage is 33-4/13. From the
construction of this table the per centage of alcohol by weight may also
be found. For instance: we multiply the number representing the
_volumes_ of alcohol (given in the table for any determinate specific
gravity of the mixture) by the specific gravity of the pure alcohol,
that is, by 7939, and the product is the number of pounds of alcohol in
so many pounds as the specific gravity multiplied by 100 gives. Thus, in
the mixture of 9510 specific gravity, there are 40 measures of alcohol;
hence there are also in 95,100 pounds of this spirit 7939 + 40 = 31·756
pounds of alcohol; and in 100 pounds of the spirits of 0·9510 specific
gravity, 33·39 pounds of alcohol are contained.

As the preceding table gives the true alcoholic content when the portion
of spirit under trial has the normal temperature of 60° Fahr., the
following table gives the per centage of alcohol for the specific
gravities corresponding to the accompanying temperatures.

For example: if we have a spirituous liquor at 80° Fahr., whose specific
gravity is 0·9342, the alcohol present is 45 per cent. of the volume, or
that specific gravity at that temperature is equal to the specific
gravity 0·9427 at the normal temperature of 60° Fahr. This table may
also be employed for every degree of the thermometer and every per
centage, so as to save computation for the intervals. It is evident from
inspection that a difference of 5° Fahr. in the temperature changes the
specific gravity of the liquor by a difference nearly equal to 1 volume
per cent. of alcohol; thus at 35° and 85° Fahr. the very same specific
gravity of the liquor shows nearly 10 volumes per cent. of alcohol more
or less; the same, for example, at 60 and 40 per cent.

  +-------+-----------------------------------------------------------+
  |Alcohol|                       Temperature.                        |
  |  per  +----+----+----+----+----+----+----+----+----+----+----+----+
  | cent. | 30°| 35°| 40°| 45°| 50°| 55°| 60°| 65°| 70°| 75°| 80°| 85°|
  |       |  F.|  F.|  F.|  F.|  F.|  F.|  F.|  F.|  F.|  F.|  F.|  F.|
  +-------+----+----+----+----+----+----+----+----+----+----+----+----+
  |    0  |9994|9997|9997|9998|9997|9994|9991|9987|9991|9976|9970|9962|
  |    5  |9924|9926|9926|9926|9925|9922|9919|9915|9909|9903|9897|9889|
  |   10  |9868|9869|9868|9867|9865|9861|9857|9852|9845|9839|9831|9823|
  |   15  |9823|9822|9820|9817|9813|9807|9802|9796|9788|9779|9771|9761|
  |   20  |9786|9782|9777|9772|9766|9759|9751|9743|9733|9722|9711|9700|
  |   25  |9753|9746|9738|9729|9720|9709|9700|9690|9678|9665|9652|9638|
  |   30  |9717|9707|9695|9684|9672|9659|9646|9632|9618|9603|9588|9572|
  |   35  |9671|9658|9644|9629|9614|9599|9583|9566|9549|9532|9514|9495|
  |   40  |9615|9598|9581|9563|9546|9528|9510|9491|9472|9452|9433|9412|
  |   45  |9544|9525|9506|9486|9467|9447|9427|9406|9385|9364|9342|9320|
  |   50  |9460|9440|9420|9399|9378|9356|9335|9313|9290|9267|9244|9221|
  |   55  |9368|9347|9325|9302|9279|9256|9234|9211|9187|9163|9139|9114|
  |   60  |9267|9245|9222|9198|9174|9150|9126|9102|9076|9051|9026|9000|
  |   65  |9162|9138|9113|9088|9063|9038|9013|8988|8962|8936|8909|8882|
  |   70  |9046|9021|8996|8970|8944|8917|8892|8866|8839|8812|8784|8756|
  |   75  |8925|8899|8873|8847|8820|8792|8765|8738|8710|8681|8652|8622|
  |   80  |8798|8771|8744|8716|8688|8659|8631|8602|8573|8544|8514|8483|
  |   85  |8663|8635|8606|8577|8547|8517|8488|8458|8427|8396|8365|8333|
  |   90  |8517|8486|8455|8425|8395|8363|8322|8300|8268|8236|8204|8171|
  +-------+----+----+----+----+----+----+----+----+----+----+----+----+

The importance of extreme accuracy in determining the density of
alcoholic mixtures in the United Kingdom, on account of the great
revenue derived from them to the State, and their consequent high price
in commerce, induced the Lords of the Treasury a few years ago to
request the Royal Society to examine the construction and mode of
applying the instrument now in use for ascertaining and charging the
duty on spirits. This instrument, which is known and described in the
law as Sikes’s hydrometer, possesses, in many respects, decided
advantages over those formerly in use. The committee of the Royal
Society state, that a definite mixture of alcohol and water is as
invariable in its value as absolute alcohol can be; and can be more
readily, and with equal accuracy, identified by that only quality or
condition to which recourse can be had in practice, namely, specific
gravity. The committee further proposed, that the standard spirit be
that which, consisting of alcohol and water alone, shall have a specific
gravity of 0·92 at the temperature of 62° Fahr., water being unity at
the same temperature; or, in other words, that it shall at 62° weigh
92/100 or 23/25 of an equal bulk of water at the same temperature.

This standard is rather weaker than the old proof, which was 12/13, or
0·923; or in the proportion of nearly 1·1 gallon of the present proof
spirit per cent. The proposed standard will contain nearly one half by
weight of absolute alcohol. The hydrometer ought to be so graduated as
to give the indication of strength; not upon an arbitrary scale, but in
terms of specific gravity at the temperature of 62°.

The committee recommend the construction of an equation table, which
shall indicate the same strength of spirit at every temperature. Thus in
standard spirit at 62° the hydrometer would indicate 920, which in this
table would give proof spirit. If that same spirit were cooled to 40°,
the hydrometer would indicate some higher number; but which, being
combined in the table with the temperature as indicated by the
thermometer, should still give proof or standard spirit as the result.

It is considered advisable, in this and the other tables, not to express
the quality of the spirit by any number over or under proof, but to
indicate at once the number of gallons of standard spirit contained in,
or equivalent to, 100 gallons of the spirit under examination. Thus,
instead of saying 23 over proof, it is proposed to insert 123; and in
place of 35·4 under proof, to insert its difference to 100, or 64·6.

It has been considered expedient to recommend a second table to be
constructed, so as to show the bulk of spirit of any strength at any
temperature, relative to a standard bulk of 100 gallons at 62°. In this
table a spirit which had diminished in volume, at any given temperature,
0·7 per cent., for example, would be expressed by 99·3; and a spirit
which had increased at any given temperature 0·7 per cent., by 100·7.

When a sample of spirit, therefore, has been examined by the hydrometer
and thermometer, these tables will give first the proportion of standard
spirit at the observed temperature, and next the change of bulk of such
spirit from what it would be at the standard temperature. Thus, at the
temperature of 51°, and with an indication (sp. gr.) of 8240, 100
gallons of the spirit under examination would be shown by the first
table to be equal to 164·8 gallons of standard spirit of that
temperature; and by the second table it would appear that 99·3 gallons
of the same spirit would become 100 at 62°, or in reality contain the
164·8 gallons of spirit in that state only in which it is to be taxed.

But as it is considered that neither of these tables can alone be used
for charging the duty (for neither can express the actual quantity of
spirit of a specific gravity of 0·92 at 62° in 100 gallons of stronger
or weaker spirit at temperatures above or below 62°), it is considered
essential to have a third table, combining the two former, and
expressing this relation directly, so that upon mere inspection it shall
indicate the proportion of standard spirit in 100 gallons of that under
examination in its then present state. In this table the quantities
should be set down in the actual number of gallons of standard spirit at
62°, equivalent to 100 of the spirit under examination; and the column
of quantities may be expressed by the term _value_, as it in reality
expresses the proportion of the only valuable substance present. As this
will be the only table absolutely necessary to be used with the
instrument for the purposes of the excise, it may, perhaps, be thought
unnecessary to print the former two.

The following specimen table has been given by the committee:--

  +-------------------------------++----------------------------+
  |       Temperature 45°.        ||       Temperature 75°.     |
  +--------------+---------+------++-----------+---------+------+
  |Indication.[3]|Strength.|Value.||Indication.|Strength.|Value.|
  +--------------+---------+------++-----------+---------+------+
  |    9074      |  114·5  |      ||    8941   |   114·5 |      |
  |       7      |  114·3  |      ||       4   |   114·3 |      |
  |       9      |  114·2  |      ||       5   |   114·2 |      |
  |      81      |  114·0  |      ||       8   |   114·0 |      |
  |       3      |  113·9  |      ||       9   |   113·9 |      |
  |       5      |  113·7  |      ||      52   |   113·7 |      |
  |       6      |  113·6  |      ||       3   |   113·6 |      |
  |       9      |  113·4  |      ||       6   |   113·4 |      |
  |      90      |  113·3  |      ||       7   |   113·3 |      |
  |       3      |  113·1  |      ||       9   |   113·1 |      |
  +--------------+---------+------++-----------+---------+------+

  [3] By specific gravity.

The mixture of alcohol and water, taken as spirit in Mr. Gilpin’s
tables, is that of which the specific gravity is 0·825 at 60° Fahr.,
water being unity at the same temperature. The specific gravity of water
at 60° being 1000, at 62° it is 99,981. Hence, in order to compare the
specific gravities given by Mr. Gilpin with those which would result
when the specific gravity of water at 62° is taken at unity, all the
former numbers must be divided by 99,981.

Table of the Specific Gravities of different Mixtures, by Weight, of
Alcohol and Water, at different Temperatures; constructed by Mr. Gilpin,
for the use of the British Revenue on Spirits.

  +------+-------+-------+-------+-------+-------+-------+-------+
  |Tem-  | Pure  |  100  |  100  |  100  |  100  |  100  |  100  |
  |pera- | Alco- |Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|
  |ture, | hol.  |   5   |   10  |   15  |   20  |   25  |   30  |
  |Fahr. |       | Water.| Water.| Water.| Water.| Water.| Water.|
  +------+-------+-------+-------+-------+-------+-------+-------+
  |_Deg._|       |       |       |       |       |       |       |
  |  30  |0·83896|0·84995|0·85957|0·86825|0·87585|0·88282|0·88921|
  |  35  | ·83672| ·84769| ·85729| ·86587| ·87357| ·88059| ·88701|
  |  40  | ·83445| ·84539| ·85507| ·86361| ·87184| ·87838| ·88481|
  |  45  | ·83214| ·84310| ·85277| ·86131| ·86905| ·87613| ·88255|
  |  50  | ·82977| ·84076| ·85042| ·85902| ·86676| ·87384| ·88030|
  |  55  | ·82736| ·83834| ·84802| ·85664| ·86441| ·87150| ·87796|
  |  60  | ·82500| ·83599| ·84568| ·85430| ·86208| ·86918| ·87569|
  |  65  | ·82262| ·83362| ·84334| ·85193| ·85976| ·86686| ·87337|
  |  70  | ·82023| ·83124| ·84092| ·84951| ·85736| ·86451| ·87105|
  |  75  | ·81780| ·82878| ·83851| ·84710| ·85496| ·86212| ·86864|
  |  80  | ·81530| ·82631| ·83603| ·84467| ·85248| ·85966| ·86622|
  |  85  | ·81291| ·82396| ·83371| ·84243| ·85036| ·85757| ·86411|
  |  90  | ·81044| ·82150| ·83126| ·84001| ·84797| ·85518| ·86172|
  |  95  | ·80794| ·81900| ·82877| ·83753| ·84550| ·85272| ·85928|
  | 100  | ·80548| ·81657| ·82630| ·83513| ·84038| ·85031| ·85688|
  +------+-------+-------+-------+-------+-------+-------+-------+

  +------+-------+-------+-------+-------+--------+-------+-------+
  |Tem-  |  100  |  100  |  100  |  100  |  100   |  100  |  100  |
  |pera- |Alcohol|Alcohol|Alcohol|Alcohol|Alcohol |Alcohol|Alcohol|
  |ture, |   35  |   40  |   45  |   50  |   55   |   60  |   65  |
  |Fahr. | Water.| Water.| Water.| Water.| Water. | Water.| Water.|
  +------+-------+-------+-------+-------+--------+-------+-------+
  |_Deg._|       |       |       |       |        |       |       |
  |  30  |0·89511|0·90054|0·90558|0·91023|0·91449 |0·91847|0·92217|
  |  35  | ·89294| ·89839| ·90345| ·90811| ·91241 | ·91640| ·92009|
  |  40  | ·89073| ·89617| ·90127| ·90596| ·91026 | ·91428| ·91799|
  |  45  | ·88849| ·89396| ·89909| ·90380| ·90812 | ·91211| ·91584|
  |  50  | ·88626| ·89174| ·89684| ·90160| ·90596 | ·90997| ·91370|
  |  55  | ·88393| ·88945| ·89458| ·89933| ·90367 | ·90768| ·91144|
  |  60  | ·88169| ·88720| ·89232| ·89707| ·90144 | ·90549| ·90927|
  |  65  | ·87938| ·88490| ·89006| ·89479| ·89920 | ·90328| ·90707|
  |  70  | ·87705| ·88254| ·88773| ·89252| ·89695 | ·90104| ·90484|
  |  75  | ·87466| ·88018| ·88538| ·89018| ·89464 | ·89872| ·90252|
  |  80  | ·87228| ·87776| ·88301| ·88781| ·89225 | ·89639| ·90021|
  |  85  | ·87021| ·87590| ·88120| ·88609| ·89043 | ·89460| ·89843|
  |  90  | ·86787| ·87360| ·87889| ·88376| ·88817 | ·89230| ·89617|
  |  95  | ·86542| ·87114| ·87654| ·88146| ·88588 | ·89003| ·89390|
  | 100  | ·86302| ·86879| ·87421| ·87915| ·883671| ·88769| ·89158|
  +------+-------+-------+-------+-------+--------+-------+-------+

  +------+-------+-------+-------+-------+-------+-------+-------+
  |Tem-  |  100  |  100  |  100  |  100  |  100  |  100  |  100  |
  |pera- |Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|
  |ture, |   70  |   75  |   80  |   85  |   90  |   95  |  100  |
  |Fahr. | Water.| Water.| Water.| Water.| Water.| Water.| Water.|
  +------+-------+-------+-------+-------+-------+-------+-------+
  |_Deg._|       |       |       |       |       |       |       |
  |  30  |0·92563|0·92889|0·93191|0·93474|0·93741|0·93991|0·94222|
  |  35  | ·92355| ·92680| ·92986| ·93274| ·93541| ·93790| ·94025|
  |  40  | ·92151| ·92476| ·92783| ·93072| ·93341| ·93592| ·93827|
  |  45  | ·91937| ·92264| ·92570| ·92859| ·93131| ·93382| ·93621|
  |  50  | ·91723| ·92051| ·92358| ·92647| ·92919| ·93177| ·93419|
  |  55  | ·91502| ·91837| ·92145| ·92436| ·92707| ·92963| ·93208|
  |  60  | ·91287| ·91622| ·91933| ·92225| ·92499| ·92758| ·93002|
  |  65  | ·91066| ·91400| ·91715| ·92010| ·92283| ·92546| ·92794|
  |  70  | ·90847| ·91181| ·91493| ·91793| ·92069| ·92333| ·92580|
  |  75  | ·90617| ·90952| ·91270| ·91569| ·91849| ·92111| ·92364|
  |  80  | ·90385| ·90723| ·91046| ·91340| ·91622| ·91891| ·92142|
  |  85  | ·90209| ·90558| ·90882| ·91186| ·91465| ·91729| ·91969|
  |  90  | ·89988| ·90342| ·90688| ·90967| ·91248| ·91511| ·91751|
  |  95  | ·89763| ·90119| ·90443| ·90747| ·91029| ·91290| ·91531|
  | 100  | ·89536| ·89889| ·90215| ·90522| ·90805| ·91066| ·91310|
  +------+-------+-------+-------+-------+-------+-------+-------+

  +------+-------+-------+-------+-------+-------+-------+-------+
  |Tem-  |   95  |  90   |  85   |  80   |  75   |  70   |  65   |
  |pera- |Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|
  |ture, |  100  |  100  | 100   | 100   | 100   | 100   | 100   |
  |Fahr. | Water.| Water.| Water.| Water.| Water.| Water.| Water.|
  +------+-------+-------+-------+-------+-------+-------+-------+
  |_Deg._|       |       |       |       |       |       |       |
  |  30  |0·94447|0·94675|0·94920|0·95173|0·95429|0·95681|0·95944|
  |  35  | ·94249| ·94484| ·94734| ·94988| ·95246| ·95502| ·95772|
  |  40  | ·94058| ·94295| ·94547| ·94802| ·95060| ·95328| ·95602|
  |  45  | ·93860| ·94096| ·94348| ·94605| ·94871| ·95143| ·95423|
  |  50  | ·93658| ·93897| ·94149| ·94414| ·94683| ·94958| ·95243|
  |  55  | ·93452| ·93696| ·93948| ·94213| ·94486| ·94767| ·95057|
  |  60  | ·93247| ·93493| ·93749| ·94018| ·94296| ·94579| ·94876|
  |  65  | ·93040| ·93285| ·93546| ·93822| ·94099| ·94388| ·94689|
  |  70  | ·92828| ·93076| ·93337| ·93616| ·93898| ·94193| ·94500|
  |  75  | ·92613| ·92865| ·93132| ·93413| ·93695| ·93989| ·94301|
  |  80  | ·92393| ·92646| ·92917| ·93201| ·93488| ·93785| ·94102|
  +------+-------+-------+-------+-------+-------+-------+-------+

  +------+-------+-------+-------+-------+-------+-------+-------+
  |Tem-  |  60   |  55   |  50   |  45   |  40   |  35   |  30   |
  |pera- |Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|
  |ture, | 100   | 100   | 100   | 100   | 100   | 100   | 100   |
  |Fahr. | Water.| Water.| Water.| Water.| Water.| Water.| Water.|
  +------+-------+-------+-------+-------+-------+-------+-------+
  |_Deg._|       |       |       |       |       |       |       |
  |  30  |0·96209|0·96470|0·96719|0·96967|0·97200|0·97418|0·97635|
  |  35  | ·96048| ·96315| ·96579| ·96840| ·97086| ·97319| ·97556|
  |  40  | ·95879| ·96159| ·96434| ·96706| ·96967| ·97220| ·97472|
  |  45  | ·95703| ·95993| ·96280| ·96563| ·96840| ·97110| ·97384|
  |  50  | ·95534| ·95831| ·96126| ·96420| ·96708| ·96995| ·97284|
  |  55  | ·95357| ·95662| ·95966| ·96272| ·96575| ·96877| ·97181|
  |  60  | ·95181| ·95493| ·95804| ·96122| ·96437| ·96752| ·97074|
  |  65  | ·95000| ·95318| ·95635| ·95962| ·96288| ·96620| ·96959|
  |  70  | ·94813| ·95139| ·95469| ·95802| ·96143| ·96484| ·96836|
  |  75  | ·94623| ·94957| ·95292| ·95638| ·95987| ·96344| ·96708|
  |  80  | ·94431| ·94768| ·95111| ·95467| ·95826| ·96192| ·96568|
  +------+-------+-------+-------+-------+-------+-------+-------+

  +------+-------+-------+-------+-------+-------+
  |Tem-  |  25   |  20   |  15   |  10   |   5   |
  |pera- |Alcohol|Alcohol|Alcohol|Alcohol|Alcohol|
  |ture, | 100   | 100   | 100   | 100   | 100   |
  |Fahr. | Water.| Water.| Water.| Water.| Water.|
  +------+-------+-------+-------+-------+-------+
  |_Deg._|       |       |       |       |       |
  |  30  |0·97860|0·98108|0·98412|0·98804|0·99334|
  |  35  | ·97801| ·98076| ·98397| ·98804| ·99344|
  |  40  | ·97737| ·98033| ·98373| ·98795| ·99345|
  |  45  | ·97666| ·97980| ·98338| ·98774| ·99338|
  |  50  | ·97589| ·97920| ·98293| ·98745| ·99316|
  |  55  | ·97500| ·97847| ·98239| ·98702| ·99284|
  |  60  | ·97410| ·97771| ·98176| ·98654| ·99244|
  |  65  | ·97309| ·97688| ·98106| ·98594| ·99194|
  |  70  | ·97203| ·97596| ·98028| ·98527| ·99134|
  |  75  | ·97086| ·97495| ·97943| ·98454| ·99066|
  |  80  | ·96963| ·97385| ·97845| ·98367| ·98991|
  +------+-------+-------+-------+-------+-------+

Experiments were made, by direction of the committee, to verify Gilpin’s
tables, which showed that the error introduced in ascertaining the
strength of spirits by tables founded on Gilpin’s numbers must be quite
insensible in the practice of the revenue. The discrepancies thus
detected, on a mixture of a given strength, did not amount in any one
instance to unity in the fourth place of decimals. From a careful
inspection of such documents the committee are of opinion, that Gilpin’s
tables possess a degree of accuracy far surpassing what could be
expected, and sufficiently perfect for all practical or scientific
purposes.

The following table is given by Mr. Lubbock, for converting the
_apparent_ specific gravity, or _indication_, into true specific
gravity:--

  +-----+-----------------------------------------+-----+
  |Indi-|      -        Temperature        +      |Indi-|
  | ca- +------+------+------+------+------+------+ ca- |
  |tion.|  30° |  32° |  37° |  42° |  47° |  52° |tion.|
  +-----+------+------+------+------+------+------+-----+
  | ·82 |·00083|·00078|·00065|·00052|·00039|·00025| ·82 |
  | ·83 |·00084|·00079|·00066|·00052|·00039|·00026| ·83 |
  | ·84 |·00085|·00080|·00066|·00053|·00039|·00026| ·84 |
  | ·85 |·00086|·00081|·00067|·00054|·00040|·00026| ·85 |
  | ·86 |·00087|·00082|·00068|·00054|·00040|·00027| ·86 |
  | ·87 |·00088|·00083|·00069|·00055|·00041|·00027| ·87 |
  | ·88 |·00089|·00084|·00070|·00055|·00041|·00027| ·88 |
  | ·89 |·00090|·00085|·00070|·00055|·00042|·00028| ·89 |
  | ·90 |·00091|·00085|·00071|·00056|·00042|·00028| ·90 |
  | ·91 |·00092|·00086|·00072|·00057|·00043|·00028| ·91 |
  | ·92 |·00093|·00087|·00073|·00058|·00043|·00029| ·92 |
  | ·93 |·00094|·00088|·00073|·00059|·00044|·00029| ·93 |
  | ·94 |·00095|·00089|·00074|·00059|·00044|·00029| ·94 |
  | ·95 |·00096|·00090|·00075|·00060|·00045|·00029| ·95 |
  | ·96 |·00097|·00091|·00076|·00060|·00045|·00030| ·96 |
  | ·97 |·00098|·00092|·00077|·00061|·00046|·00030| ·97 |
  | ·98 |·00099|·00093|·00077|·00062|·00046|·00030| ·98 |
  | ·99 |·00100|·00094|·00078|·00062|·00047|·00031| ·99 |
  |1·00 |·00101|·00095|·00079|·00063|·00047|·00031|1·00 |
  +-----+------+------+------+------+------+------+-----+

  +-----+-----------------------------------------+-----+
  |Indi-|      -        Temperature        +      |Indi-|
  | ca- +------+------+------+------+------+------+ ca- |
  |tion.|  57° |  62° |  67° |  72° |  77° |  80° |tion.|
  +-----+------+------+------+------+------+------+-----+
  | ·82 |·00012|      |·00011|·00024|·00035|·00042| ·82 |
  | ·83 |·00012|      |·00012|·00024|·00036|·00042| ·83 |
  | ·84 |·00013|      |·00012|·00024|·00036|·00043| ·84 |
  | ·85 |·00013|      |·00012|·00025|·00037|·00043| ·85 |
  | ·86 |·00013|      |·00012|·00025|·00037|·00044| ·86 |
  | ·87 |·00013|      |·00012|·00025|·00037|·00044| ·87 |
  | ·88 |·00013|      |·00012|·00026|·00038|·00045| ·88 |
  | ·89 |·00013|      |·00012|·00026|·00038|·00045| ·89 |
  | ·90 |·00014|      |·00013|·00026|·00039|·00046| ·90 |
  | ·91 |·00014|      |·00013|·00026|·00039|·00046| ·91 |
  | ·92 |·00014|      |·00013|·00027|·00040|·00047| ·92 |
  | ·93 |·00014|      |·00013|·00027|·00040|·00047| ·93 |
  | ·94 |·00014|      |·00013|·00027|·00040|·00048| ·94 |
  | ·95 |·00014|      |·00013|·00028|·00041|·00048| ·95 |
  | ·96 |·00014|      |·00013|·00028|·00041|·00049| ·96 |
  | ·97 |·00015|      |·00014|·00028|·00042|·00049| ·97 |
  | ·98 |·00015|      |·00014|·00028|·00042|·00050| ·98 |
  | ·99 |·00015|      |·00014|·00029|·00043|·00050| ·99 |
  |1·00 |·00015|      |      |      |      |      |1·00 |
  +-----+------+------+------+------+------+------+-----+

[Illustration: _Fig._ 5.]

The hydrometer constructed, under the directions of the Commissioners of
Excise, by Mr. Bate, has a scale of 4 inches in length divided into 100
parts, and 9 weights. It has thus a range of 900 divisions, and
expresses specific gravities at the temperature of 62° Fahr. In order to
render this instrument so accurate a measurer of the specific gravity,
at the standard temperature, as to involve no error of an appreciable
amount, Mr. Bate has constructed the weights (which in this instrument
are immersed in the fluid of different specific gravities) so that each
successive weight should have an increase of bulk over the preceding
weight equal to that part of the stem occupied by the scale, and an
increase of weight sufficient to take the whole of the scale, and no
more, down to the liquid. This arrangement requires great accuracy of
workmanship, and enhances the price of the instrument. But it allows of
increased strength in the ball, where it is very much required, and it
gives, upon inspection only, the indication (apparent specific gravity)
by which the general table is to be examined and the result ascertained.
_Fig._ 5. represents this instrument and two of its nine ballast
weights. It comprehends all specific gravities between 820 and 1000. It
indicates true specific gravity with almost perfect accuracy at the
temperature of 62° Fahr.; but it does not exclude other instruments from
being used in conjunction with tables. The latter are, in fact,
independent of the instrument, and may be used with gravimeters, or any
instrument affording indications by specific gravity at a given
temperature.

The commercial value of spirituous liquors being much lower in France
than in England, a less sensible instrument becomes sufficient for the
wants of that country. Baumé’s and Cartier’s hydrometers, with short
arbitrary scales, are very much employed, but they have been lately
superseded by an ingenious and ready instrument contrived by M. Gay
Lussac, and called by him an _alcoomètre_. He takes for the term of
comparison pure alcohol by volume, at the temperature of 15° Cent., and
represents the strength of it by 100 _centimes_, or by unity.
Consequently, the strength of a spirituous liquid is the number of
centimes in volume of pure alcohol which that liquid contains at the
temperature of 15° Cent. The instrument is formed like a common
hydrometer, and is graduated for the temperature of 15° Cent. Its scale
is divided into 100 parts or degrees, each of which denotes a centime of
alcohol; the division 0 at the bottom of the stem corresponds to pure
water, and the division 100 at its top, to pure alcohol. When immersed
in a spirituous liquor at 15° Cent. (59° Fahr.) it announces its
strength directly. For example: if in spirits supposed at the
temperature of 15° Cent. it sinks to the division 50, it indicates that
the strength of this liquor is 50 per cent., or that it contains 50
centimes of pure alcohol. In our new British proof spirit, it would sink
to nearly 57, indicating 57 by volume of pure alcohol, allowing for
condensation, or 50 by weight. A table of correction is given for
temperature, which he calls “Table of real strength of spirituous
liquors.” The first vertical column of this table contains the
temperatures, from 0° to 30° Cent., and the first horizontal line the
indications of the alcoomètre. In the same table we have most
ingeniously inserted a correction for the volume of the spirits when the
temperature differs from 15° Cent. If we take 1000 litres or gallons,
measured at the temperature of 2°, of a spirituous liquor whose apparent
strength is 44^{c}; its real strength at 15° will from the preceding
mode of correction be 49^{c}. On heating this liquid to 15°, in order to
find its real specific gravity or strength, its bulk will become
greater; and, instead of 1000 litres or gallons, which it measured at
2°, we shall have 1009 at 15° C. This number is inscribed in smaller
characters in the same square cell with the real force, precisely under
49^{c}. All the numbers in small characters, printed under each _real
strength_, indicate the volume which 1000 litres of a spirituous liquor
would have, when measured at the temperature at which its apparent
strength is taken. In the above example, the quantity in litres or
gallons of pure alcohol contained in 1000 litres or gallons of the
spirits, measured at the temperature of 2°, will be, therefore,--1009
lit. × 0·49 = 494 lit. 41.

This quantity of pure alcohol, thus estimated, is called _richness of
spirit in alcohol_, or simply _richness_.

Let us take an example similar to the preceding, but at a higher
temperature than 15° Cent. Suppose we have 1000 litres measured, at the
temperature of 25°, of spirits whose apparent strength is 53^{c}, what
is the real quantity of pure alcohol which this spirit contains at the
temperature of 15°? We shall find in the table, first of all, that the
real strength of the spirits is 49^{c}·3. As to its bulk or volume, it
is very clear that the 1000 litres in cooling from 25° to 15°, will
occupy a smaller space. This volume will be 993 litres; it is inscribed
directly below 49^{c}·3, the real strength. We shall therefore have of
pure alcohol, contained in the 1000 litres of spirits, measured at the
temperature of 25°, or their _richness_, 993 lit. × 0·493 = 489 lit. 55.

Alcometrical Table of real Strength, by M. Gay Lussac.

  +-------+------+------+------+------+------+------+------+------+
  |Temper-|31^{c}|32^{c}|33^{c}|34^{c}|35^{c}|36^{c}|37^{c}|38^{c}|
  | ature |      |      |      |      |      |      |      |      |
  |  C.   |      |      |      |      |      |      |      |      |
  +-------+------+------+------+------+------+------+------+------+
  | _Deg._|      |      |      |      |      |      |      |      |
  |   10  | 33·0 |  34  |  35  |  36  |  37  |  38  |  39  |  40  |
  |       | 1002 | 1002 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+------+------+------+------+
  |   11  | 32·6 | 33·6 | 34·6 | 35·6 | 36·6 | 37·6 | 38·6 | 39·6 |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   12  | 32·2 | 33·2 | 34·2 | 35·2 | 36·2 | 37·2 | 38·2 | 39·2 |
  |       | 1001 | 1001 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   13  | 31·8 | 32·8 | 33·8 | 34·8 | 35·8 | 36·8 | 37·8 | 38·8 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   14  | 31·4 | 32·4 | 33·4 | 34·4 | 35·4 | 36·4 | 37·4 | 38·4 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   15  |  31  |  32  |  33  |  34  |  35  |  36  |  37  |  38  |
  |       | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+------+------+------+------+
  |   16  | 30·6 | 31·6 | 32·5 | 33·5 | 34·5 | 35·5 | 36·5 | 37·5 |
  |       | 1000 | 1000 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   17  | 30·2 | 31·2 | 32·1 | 33·1 | 34·1 | 35·1 | 36·1 | 37·1 |
  |       |  999 |  999 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   18  | 29·8 | 30·8 | 31·7 | 32·7 | 33·7 | 34·7 | 35·7 | 36·7 |
  |       |  999 |  999 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   19  | 29·4 | 30·4 | 31·3 | 32·3 | 33·3 | 34·3 | 35·3 | 36·3 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   20  |  29  |  30  | 30·9 | 31·9 | 32·9 | 33·9 | 34·9 | 35·9 |
  |       |  998 |  998 |  997 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   21  | 28·6 | 29·6 | 30·5 | 31·5 | 32·5 | 33·5 | 34·5 | 35·5 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  997 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   22  | 28·2 | 29·2 | 30·1 | 31·1 | 32·1 | 33·1 | 34·1 | 35·1 |
  |       |  997 |  997 |  996 |  996 |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   23  | 27·8 | 28·8 | 29·7 | 30·7 | 31·7 | 32·7 | 33·7 | 34·7 |
  |       |  996 |  996 |  996 |  996 |  996 |  996 |  996 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   24  | 27·4 | 28·4 | 29·3 | 30·3 | 31·3 | 32·3 | 33·3 | 34·3 |
  |       |  996 |  996 |  995 |  995 |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   25  |  27  |  28  | 28·9 | 29·9 | 30·9 | 31·9 | 32·9 | 33·9 |
  |       |  995 |  995 |  995 |  995 |  995 |  994 |  994 |  994 |
  +-------+------+------+------+------+------+------+------+------+

  +-------+------+------+------+------+------+------+------+------+
  |Temper-|39^{c}|40^{c}|41^{c}|42^{c}|43^{c}|44^{c}|45^{c}|46^{c}|
  | ature |      |      |      |      |      |      |      |      |
  |  C.   |      |      |      |      |      |      |      |      |
  +-------+------+------+------+------+------+------+------+------+
  | _Deg._|      |      |      |      |      |      |      |      |
  |   10  |  41  |  42  |  43  |  44  |  45  |  46  | 46·9 | 47·9 |
  |       | 1003 | 1003 | 1003 | 1004 | 1004 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+------+------+------+------+
  |   11  | 40·6 | 41·6 | 42·6 | 43·6 | 44·6 | 45·6 | 46·6 | 47·6 |
  |       | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+------+------+------+------+
  |   12  | 40·2 | 41·2 | 42·2 | 43·2 | 44·2 | 45·2 | 46·2 | 47·2 |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   13  | 39·8 | 40·8 | 41·8 | 42·8 | 43·8 | 44·8 | 45·8 | 46·8 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   14  | 39·4 | 40·4 | 41·4 | 42·4 | 43·4 | 44·4 | 45·4 | 46·4 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   15  |  39  |  40  |  41  |  42  |  43  |  44  |  45  |  46  |
  |       | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+------+------+------+------+
  |   16  | 38·5 | 39·5 | 40·6 | 41·6 | 42·6 | 43·6 | 44·6 | 45·6 |
  |       |  999 |  999 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   17  | 38·1 | 39·1 | 40·2 | 41·2 | 42·2 | 43·2 | 44·9 | 45·2 |
  |       |  999 |  999 |  999 |  999 |  999 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   18  | 37·7 | 38·7 | 39·8 | 40·8 | 41·8 | 42·8 | 43·8 | 44·9 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   19  | 37·3 | 38·3 | 39·4 | 40·4 | 41·4 | 42·5 | 43·5 | 44·5 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   20  | 36·9 | 37·9 |  39  |  40  |  41  | 42·1 | 43·1 | 44·1 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   21  | 36·5 | 37·5 | 38·6 | 39·6 | 40·6 | 41·7 | 42·7 | 43·7 |
  |       |  996 |  996 |  996 |  996 |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   22  | 36·1 | 37·1 | 38·2 | 39·2 | 40·2 | 41·3 | 42·3 | 43·3 |
  |       |  996 |  996 |  996 |  995 |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   23  | 35·7 | 36·7 | 37·8 | 38·8 | 39·8 | 40·9 | 41·9 | 42·9 |
  |       |  995 |  995 |  995 |  995 |  995 |  994 |  994 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   24  | 35·3 | 36·3 | 37·4 | 38·4 | 39·4 | 40·5 | 41·5 | 42·5 |
  |       |  995 |  994 |  994 |  994 |  994 |  994 |  994 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   25  | 34·9 | 35·9 |  37  |  38  |  39  | 40·1 | 42·1 | 42·2 |
  |       |  994 |  994 |  994 |  994 |  993 |  993 |  993 |  993 |
  +-------+------+------+------+------+------+------+------+------+

  +-------+------+------+------+------+------+------+------+------+
  |Temper-|47^{c}|48^{c}|49^{c}|50^{c}|51^{c}|52^{c}|53^{c}|54^{c}|
  | ature |      |      |      |      |      |      |      |      |
  |  C.   |      |      |      |      |      |      |      |      |
  +-------+------+------+------+------+------+------+------+------+
  | _Deg._|      |      |      |      |      |      |      |      |
  |   10  | 48·9 | 49·9 | 50·9 | 51·8 | 52·8 | 53·8 | 54·8 | 55·8 |
  |       | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+------+------+------+------+
  |   11  | 48·6 | 49·5 | 50·5 | 51·5 | 52·5 | 53·5 | 54·4 | 55·4 |
  |       | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+------+------+------+------+
  |   12  | 48·2 | 49·2 | 50·2 | 51·1 | 52·1 | 53·1 | 54·1 |  55  |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   13  | 47·8 | 48·8 | 49·8 | 50·8 | 51·8 | 52·7 | 53·7 | 54·7 |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   14  | 47·4 | 48·4 | 49·4 | 50·4 | 51·4 | 52·3 | 53·3 | 54·3 |
  |       | 1001 | 1001 | 1001 | 1000 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   15  |  47  |  48  |  49  |  50  |  51  |  52  |  53  |  54  |
  |       | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+------+------+------+------+
  |   16  | 46·6 | 47·6 | 48·6 | 49·6 | 50·6 | 51·6 | 52·6 | 53·6 |
  |       |  999 |  999 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   17  | 46·2 | 47·2 | 48·2 | 49·2 | 50·3 | 51·3 | 52·3 | 53·3 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   18  | 45·9 | 46·9 | 47·9 | 48·9 | 49·9 | 50·9 | 51·9 | 52·9 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   19  | 45·5 | 46·5 | 47·5 | 48·5 | 49·5 | 50·6 | 51·6 | 52·6 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   20  | 45·1 | 46·1 | 47·2 | 48·2 | 49·2 | 50·2 | 51·2 | 52·2 |
  |       |  996 |  996 |  996 |  996 |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   21  | 44·8 | 45·8 | 46·8 | 47·8 | 48·8 | 49·8 | 50·8 | 51·8 |
  |       |  996 |  996 |  995 |  995 |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   22  | 44·3 | 45·3 | 46·4 | 47·4 | 48·4 | 49·4 | 50·4 | 51·4 |
  |       |  995 |  995 |  995 |  995 |  995 |  995 |  995 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   23  | 43·9 | 44·9 |  46  |  47  |  48  | 49·1 | 50·1 | 51·1 |
  |       |  994 |  994 |  994 |  994 |  994 |  994 |  994 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   24  | 43·6 | 44·6 | 45·6 | 46·6 | 47·6 | 48·7 | 49·7 | 50·7 |
  |       |  994 |  994 |  993 |  993 |  993 |  993 |  993 |  693 |
  |       +------+------+------+------+------+------+------+------+
  |   25  | 43·2 | 44·2 | 45·2 | 46·3 | 47·3 | 48·3 | 49·3 | 50·3 |
  |       |  993 |  993 |  993 |  993 |  993 |  993 |  993 |  992 |
  +-------+------+------+------+------+------+------+------+------+

  +-------+------+------+------+------+------+------+------+------+
  |Temper-|55^{c}|56^{c}|57^{c}|58^{c}|59^{c}|60^{c}|61^{c}|62^{c}|
  | ature |      |      |      |      |      |      |      |      |
  |  C.   |      |      |      |      |      |      |      |      |
  +-------+------+------+------+------+------+------+------+------+
  | _Deg._|      |      |      |      |      |      |      |      |
  |   10  | 56·8 | 57·8 | 58·8 | 59·7 | 60·7 | 61·7 | 62·7 | 63·7 |
  |       | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+------+------+------+------+
  |   11  | 56·4 | 57·4 | 58·4 | 59·4 | 60·4 | 61·4 | 62·4 | 63·4 |
  |       | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+------+------+------+------+
  |   12  |  56  |  57  |  58  |  59  |  60  |  61  |  62  |  63  |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   13  | 55·7 | 56·7 | 57·7 | 58·7 | 59·7 | 60·7 | 61·7 | 62·7 |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   14  | 55·3 | 56·3 | 57·3 | 58·3 | 59·3 | 60·3 | 61·3 | 62·3 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   15  |  55  |  56  |  57  |  58  |  59  |  60  |  61  |  62  |
  |       | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+------+------+------+------+
  |   16  | 54·6 | 55·6 | 56·6 | 57·6 | 58·6 | 59·6 | 60·6 | 61·7 |
  |       |  999 |  999 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   17  | 54·3 | 55·3 | 56·3 | 57·3 | 58·3 | 59·3 | 60·3 | 61·3 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   18  | 53·9 | 54·9 | 55·9 | 56·9 | 57·9 | 58·9 | 59·9 |  61  |
  |       |  998 |  998 |  998 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   19  | 53·6 | 54·6 | 55·6 | 56·6 | 57·6 | 58·6 | 59·6 | 60·6 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   20  | 53·2 | 54·2 | 55·2 | 56·2 | 57·2 | 58·2 | 59·2 | 60·3 |
  |       |  996 |  996 |  996 |  996 |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   21  | 52·9 | 53·9 | 54·9 | 55·9 | 56·9 | 57·9 | 58·9 | 59·9 |
  |       |  995 |  995 |  995 |  995 |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   22  | 52·5 | 53·5 | 54·5 | 55·5 | 56·5 | 57·5 | 58·5 | 59·5 |
  |       |  994 |  994 |  994 |  994 |  994 |  994 |  994 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   23  | 52·1 | 53·1 | 54·1 | 55·1 | 56·1 | 57·1 | 58·1 | 59·2 |
  |       |  994 |  994 |  994 |  993 | 993  |  993 |  993 |  993 |
  |       +------+------+------+------+------+------+------+------+
  |   24  | 51·8 | 52·8 | 53·8 | 54·8 | 55·8 | 56·8 | 57·8 | 58·9 |
  |       |  993 |  993 |  993 |  993 |  993 |  992 |  992 |  992 |
  |       +------+------+------+------+------+------+------+------+
  |   25  | 51·4 | 52·4 | 53·4 | 54·4 | 55·5 | 56·5 | 57·5 | 58·5 |
  |       |  992 |  992 |  992 |  992 |  992 |  992 |  992 |  992 |
  +-------+------+------+------+------+------+------+------+------+

  +-------+------+------+------+------+------+------+------+------+
  |Temper-|63^{c}|64^{c}|65^{c}|66^{c}|67^{c}|68^{c}|69^{c}|70^{c}|
  | ature |      |      |      |      |      |      |      |      |
  |  C.   |      |      |      |      |      |      |      |      |
  +-------+------+------+------+------+------+------+------+------+
  | _Deg._|      |      |      |      |      |      |      |      |
  |   10  | 64·7 | 65·7 | 66·7 | 67·6 | 68·6 | 69·6 | 70·6 | 71·6 |
  |       | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+------+------+------+------+
  |   11  | 64·4 | 65·4 | 66·4 | 67·3 | 68·3 | 69·3 | 70·3 | 71·3 |
  |       | 1003 | 1003 | 1003 | 1003 | 1003 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+------+------+------+------+
  |   12  |  64  |  65  |  66  |  67  |  68  |  69  |  70  |  71  |
  |       | 1002 | 1002 | 1002 | 1002 | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+------+------+------+------+
  |   13  | 63·7 | 64·7 | 65·7 | 66·7 | 67·7 | 68·7 | 69·6 | 70·6 |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   14  | 63·3 | 64·3 | 65·3 | 66·3 | 67·3 | 68·3 | 69·3 | 70·3 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   15  |  63  |  64  |  65  |  66  |  67  |  68  |  69  |  70  |
  |       | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+------+------+------+------+
  |   16  | 62·7 | 63·7 | 64·7 | 65·7 | 66·7 | 67·7 | 68·7 | 69·7 |
  |       |  999 |  999 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   17  | 62·3 | 63·3 | 64·3 | 65·3 | 66·3 | 67·3 | 68·3 | 69·3 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   18  |  62  |  63  |  64  |  65  |  66  |  67  |  68  |  69  |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   19  | 61·6 | 62·7 | 63·7 | 64·7 | 65·7 | 66·7 | 67·7 | 68·7 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   20  | 61·3 | 62·3 | 63·3 | 64·3 | 65·4 | 66·4 | 67·4 | 68·4 |
  |       |  996 |  996 |  996 |  996 |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   21  |  61  |  62  |  63  |  64  |  65  |  66  |  67  | 68·1 |
  |       |  995 |  995 |  995 |  995 |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   22  | 60·6 | 61·6 | 62·7 | 63·7 | 64·7 | 65·7 | 66·7 | 67·7 |
  |       |  994 |  994 |  994 |  994 |  994 |  994 |  994 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   23  | 60·2 | 61·3 | 62·3 | 63·3 | 64·3 | 65·4 | 66·4 | 67·4 |
  |       |  993 |  993 |  993 |  993 |  993 |  993 |  993 |  993 |
  |       +------+------+------+------+------+------+------+------+
  |   24  | 59·9 |  61  |  62  |  63  |  64  |  65  |  66  | 67·1 |
  |       |  992 |  992 |  992 |  992 |  992 |  992 |  992 |  992 |
  |       +------+------+------+------+------+------+------+------+
  |   25  | 59·5 | 60·6 | 61·6 | 62·6 | 63·7 | 64·7 | 65·7 | 66·7 |
  |       |  992 |  991 |  991 |  991 |  991 |  991 |  991 |  991 |
  +-------+------+------+------+------+------+------+------+------+

  +-------+------+------+------+------+------+------+------+------+
  |Temper-|71^{c}|72^{c}|73^{c}|74^{c}|75^{c}|76^{c}|77^{c}|78^{c}|
  | ature |      |      |      |      |      |      |      |      |
  |  C.   |      |      |      |      |      |      |      |      |
  +-------+------+------+------+------+------+------+------+------+
  | _Deg._|      |      |      |      |      |      |      |      |
  |   10  | 72·6 | 73·5 | 74·5 | 75·5 | 76·5 | 77·5 | 78·5 | 79·5 |
  |       | 1004 | 1004 | 1005 | 1005 | 1005 | 1005 | 1005 | 1005 |
  |       +------+------+------+------+------+------+------+------+
  |   11  | 72·3 | 73·2 | 74·2 | 75·2 | 76·2 | 77·2 | 78·2 | 79·2 |
  |       | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+------+------+------+------+
  |   12  |  72  | 72·9 | 73·9 | 74·9 | 75·9 | 76·9 | 77·9 | 78·9 |
  |       | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+------+------+------+------+
  |   13  | 71·6 | 72·6 | 73·6 | 74·6 | 75·6 | 76·6 | 77·6 | 78·6 |
  |       | 1002 | 1002 | 1002 | 1002 | 1092 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   14  | 71·3 | 72·3 | 73·3 | 74·3 | 75·3 | 76·3 | 77·3 | 78·3 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   15  |  71  |  72  |  73  |  74  |  75  |  76  |  77  |  78  |
  |       | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+------+------+------+------+
  |   16  | 70·7 | 71·7 | 72·7 | 73·7 | 74·7 | 75·7 | 76·7 | 77·7 |
  |       |  999 |  999 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   17  | 70·3 | 71·3 | 72·3 | 73·3 | 74·3 | 75·4 | 76·4 | 77·4 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   18  |  70  |  71  |  72  |  73  |  74  | 75·1 | 76·1 | 77·1 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   19  | 69·7 | 70·7 | 71·7 | 72·7 | 73·7 | 74·7 | 75·8 | 76·8 |
  |       |  996 |  996 |  996 |  996 |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   20  | 69·4 | 70·4 | 71·4 | 72·4 | 73·4 | 74·4 | 75·5 | 76·5 |
  |       |  996 |  996 |  995 |  995 |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   21  | 69·1 | 70·1 | 71·1 | 72·1 | 73·1 | 74·1 | 75·2 | 76·2 |
  |       |  995 |  995 |  995 |  994 |  994 |  994 |  994 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   22  | 68·8 | 69·8 | 70·8 | 71·8 | 72·8 | 73·8 | 74·8 | 75·9 |
  |       |  994 |  994 |  994 |  994 |  993 |  993 |  993 |  993 |
  |       +------+------+------+------+------+------+------+------+
  |   23  | 68·4 | 69·4 | 70·5 | 71·5 | 72·5 | 73·5 | 74·5 | 75·5 |
  |       |  993 |  993 |  993 |  993 |  992 |  992 |  992 |  992 |
  |       +------+------+------+------+------+------+------+------+
  |   24  | 68·1 | 69·1 | 70·1 | 71·2 | 72·2 | 73·2 | 74·2 | 75·2 |
  |       |  992 |  992 |  992 |  992 |  992 |  992 |  992 |  991 |
  |       +------+------+------+------+------+------+------+------+
  |   25  | 67·8 | 68·8 | 69·8 | 70·8 | 71·8 | 72·8 | 73·9 | 74·9 |
  |       |  991 |  991 |  991 |  991 |  991 |  991 |  991 |  991 |
  +-------+------+------+------+------+------+------+------+------+

  +-------+------+------+------+------+------+------+------+------+
  |Temper-|79^{c}|80^{c}|81^{c}|82^{c}|83^{c}|84^{c}|85^{c}|86^{c}|
  | ature |      |      |      |      |      |      |      |      |
  |  C.   |      |      |      |      |      |      |      |      |
  +-------+------+------+------+------+------+------+------+------+
  | _Deg._|      |      |      |      |      |      |      |      |
  |   10  | 80·5 | 81·5 | 82·4 | 83·4 | 84·4 | 85·4 | 86·4 | 87·4 |
  |       | 1005 | 1005 | 1005 | 1005 | 1005 | 1005 | 1005 | 1005 |
  |       +------+------+------+------+------+------+------+------+
  |   11  | 80·2 | 81·2 | 82·2 | 83·1 | 84·1 | 85·1 | 86·1 | 87·1 |
  |       | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+------+------+------+------+
  |   12  | 79·9 | 80·9 | 81·9 | 82·9 | 83·9 | 84·8 | 85·8 | 86·8 |
  |       | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+------+------+------+------+
  |   13  | 79·6 | 80·6 | 81·6 | 82·6 | 83·6 | 84·6 | 85·5 | 86·5 |
  |       | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+------+------+------+------+
  |   14  | 79·3 | 80·3 | 81·3 | 82·3 | 83·3 | 84·3 | 85·3 | 86·3 |
  |       | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+------+------+------+------+
  |   15  |  79  |  80  |  81  |  82  |  83  |  84  |  85  |  86  |
  |       | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+------+------+------+------+
  |   16  | 78·7 | 79·7 | 80·7 | 81·7 | 82·7 | 83·7 | 84·7 | 85·7 |
  |       |  999 |  999 |  999 |  999 |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+------+------+------+------+
  |   17  | 78·4 | 79·4 | 80·4 | 81·4 | 82·4 | 83·4 | 84·4 | 85·4 |
  |       |  998 |  998 |  998 |  998 |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+------+------+------+------+
  |   18  | 78·1 | 79·1 | 80·1 | 81·1 | 82·1 | 83·1 | 84·1 | 85·2 |
  |       |  997 |  997 |  997 |  997 |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+------+------+------+------+
  |   19  | 77·8 | 78·8 | 79·8 | 80·8 | 81·9 | 82·9 | 83·9 | 84·9 |
  |       |  996 |  996 |  996 |  996 |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+------+------+------+------+
  |   20  | 77·5 | 78·5 | 79·5 | 80·5 | 81·6 | 82·6 | 83·6 | 84·6 |
  |       |  995 |  995 |  995 |  995 |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+------+------+------+------+
  |   21  | 77·2 | 78·2 | 79·2 | 80·2 | 81·3 | 82·3 | 83·3 | 84·3 |
  |       |  994 |  994 |  994 |  994 |  994 |  994 |  994 |  994 |
  |       +------+------+------+------+------+------+------+------+
  |   22  | 76·9 | 77·9 | 78·9 | 79·9 |  81  |  82  |  83  |  84  |
  |       |  993 |  993 |  993 |  993 |  993 |  993 |  993 |  993 |
  |       +------+------+------+------+------+------+------+------+
  |   23  | 76·6 | 77·6 | 78·6 | 79·6 | 80·7 | 81·7 | 82·7 | 83·8 |
  |       |  992 |  992 |  992 |  992 |  992 |  992 |  992 |  992 |
  |       +------+------+------+------+------+------+------+------+
  |   24  | 76·3 | 77·3 | 78·3 | 79·3 | 80·4 | 81·4 | 82·4 | 83·5 |
  |       |  991 |  991 |  991 |  991 |  991 |  991 |  991 |  991 |
  |       +------+------+------+------+------+------+------+------+
  |   25  |  76  |  77  |  78  |  79  | 80·1 | 81·1 | 82·1 | 83·2 |
  |       |  991 |  991 |  991 |  991 |  990 |  990 |  990 |  990 |
  +-------+------+------+------+------+------+------+------+------+

  +-------+------+------+------+------+
  |Temper-|87^{c}|88^{c}|89^{c}|90^{c}|
  | ature |      |      |      |      |
  |  C.   |      |      |      |      |
  +-------+------+------+------+------+
  | _Deg._|      |      |      |      |
  |   10  | 88·3 | 89·3 | 90·2 | 91·2 |
  |       | 1005 | 1005 | 1005 | 1005 |
  |       +------+------+------+------+
  |   11  | 88   | 89   | 90   | 91   |
  |       | 1004 | 1004 | 1004 | 1004 |
  |       +------+------+------+------+
  |   12  | 87·8 | 88·7 | 89·7 | 90·7 |
  |       | 1003 | 1003 | 1003 | 1003 |
  |       +------+------+------+------+
  |   13  | 87·5 | 88·5 | 89·5 | 90·5 |
  |       | 1002 | 1002 | 1002 | 1002 |
  |       +------+------+------+------+
  |   14  | 87·3 | 88·2 | 89·2 | 90·2 |
  |       | 1001 | 1001 | 1001 | 1001 |
  |       +------+------+------+------+
  |   15  |  87  |  88  |  89  |  90  |
  |       | 1000 | 1000 | 1000 | 1000 |
  |       +------+------+------+------+
  |   16  | 86·7 | 87·7 | 88·7 | 89·7 |
  |       |  999 |  999 |  999 |  999 |
  |       +------+------+------+------+
  |   17  | 86·4 | 87·4 | 88·4 | 89·5 |
  |       |  998 |  998 |  998 |  998 |
  |       +------+------+------+------+
  |   18  | 86·2 | 87·2 | 88·2 | 89·2 |
  |       |  997 |  997 |  997 |  997 |
  |       +------+------+------+------+
  |   19  | 85·9 | 86·9 | 87·9 | 88·9 |
  |       |  996 |  996 |  996 |  996 |
  |       +------+------+------+------+
  |   20  | 85·6 | 86·6 | 87·7 | 88·7 |
  |       |  995 |  995 |  995 |  995 |
  |       +------+------+------+------+
  |   21  | 85·3 | 86·4 | 87·4 | 88·4 |
  |       |  994 |  994 |  994 |  994 |
  |       +------+------+------+------+
  |   22  |  85  | 86·1 | 87·1 | 88·2 |
  |       |  993 |  993 |  993 |  993 |
  |       +------+------+------+------+
  |   23  | 84·8 | 85·8 | 86·8 | 87·9 |
  |       |  992 |  992 |  992 |  992 |
  |       +------+------+------+------+
  |   24  | 84·5 | 85·5 | 86·5 | 87·6 |
  |       |  991 |  991 |  991 |  991 |
  |       +------+------+------+------+
  |   25  | 84·2 | 85·2 | 86·3 | 87·4 |
  |       |  990 |  990 |  990 |  990 |
  +-------+------+------+------+------+

I consider the preceding table, which I have extracted from the longer
tables of M. Gay Lussac, as an important addition to the resources of
British dealers and manufacturing chemists. With the aid of his little
instrument, which may be got for a trifle from its ingenious maker, M.
Collardeau, Rue Faubourg St. Martin, at Paris, or constructed by one of
the London hydrometer artists, the per centage of real alcohol, and the
real value of any spirituous liquor, may be determined to sufficient
nicety for most purposes, in a far easier manner than by any instruments
now used in this country. It has been adopted by the Swedish government,
with M. Gay Lussac’s tables.

M. Gay Lussac’s table gives, by inspection, the true bulk of the spirits
as corrected for temperature; that is, their volume, if of the normal
temperature of 15° Cent. (59° Fahr.). Now this is important information;
for, if a person buys 1000 gallons of spirits in hot weather, and pays
for them exactly according to their strength corrected for temperature,
he will not have 1000 gallons when the weather is in its mean state. He
may lose, in this way, several gallons without being aware of it from
his hydrometer.

Sometimes, after moist autumns, when damaged grain abounds, the alcohol
distilled from its fermented wash contains a peculiar volatile body.
When we apply our nose to this species of spirits in its hot state, the
volatile substance dissolved in it irritates the eyes and nostrils: it
has very nearly the same smell as an alcoholic solution of cyanogen, as
any chemist may discover by standing near the discharge pipe of the
refrigeratory worm of a raw-grain whisky still. Such spirits intoxicate
more strongly than pure spirits of the same strength, and excite, in
many persons, even temporary frenzy. It is a volatile fatty matter, of a
very fetid odour, when obtained by itself, as I have procured it in cold
weather at some of the great distilleries in Scotland. It does not
combine with bases. At the end of a few months, it spontaneously
decomposes in the spirits, and leaves them in a less nauseous and
noxious state. By largely diluting the spirits with water, and
distilling at a moderate temperature, the greater part of this oil may
be separated. Part of it comes over with the strongest alcohol, and part
with the latter runnings, which are called by the distillers strong and
weak feints. The intermediate portion is purer spirit. The feints are
always more or less opalescent, or become so on dilution with water, and
then throw up an oily pellicle upon their surface. The charcoals of
light wood, such as pine or willow, well calcined, and infused in
sufficient quantity with the spirits prior to rectification, will
deprive them of the greater part of that oily contamination. Animal
charcoal, well calcined, has also been found useful; but it must be
macerated for some time with the empyreumatic spirits, before
distillation. Another mode of separating that offensive oil is, to
agitate the impure spirits with a quantity of a fat oil, such as olive
oil, or oil of almonds, to decant off the oil, and re-distil the spirits
with a little water.

Some foreign chemists direct empyreumatic or rank spirits, to be
rectified with the addition of chloride of lime. I have tried this
method in every way, and on a considerable scale, but never found the
spirits to be improved by it. They were rather deteriorated. See
_Brandy_, _Distillation_, _Fermentation_, _Gin_, _Rum_, _Whisky_.

Anhydrous or absolute alcohol, when swallowed, acts as a mortal poison,
not only by its peculiar stimulus on the nervous system, but by its
abstracting the aqueous particles from the soft tissue of the stomach,
with which it comes in contact, so as to destroy its organisation.
Alcohol of 0·812 consists, by experiments, of 3 atoms of carbon, 6 of
hydrogen, and 2 of oxygen; absolute alcohol consists, probably, of 2 of
carbon, 3 of hydrogen, and 1 of oxygen.


ALE. The fermented infusion of pale malted barley, usually combined with
infusion of hops. See BEER.


ALEMBIC, a STILL; which see.


ALEMBROTH, salt of. The salt of wisdom, of the alchemists; a compound of
bichloride of mercury and sal ammoniac, from which the old white
precipitate of mercury is made.


ALGAROTH, powder of. A compound of oxide and chloride of antimony, being
a precipitate obtained by pouring water into the acidulous chloride of
that metal.


ALIZARINE. See MADDER.


ALKALI. A class of chemical bodies, distinguished chiefly by their
solubility in water, and their power of neutralising acids, so as to
form saline compounds. The alkalis of manufacturing importance are,
ammonia, potash, soda, and quinia. These alkalis change the purple
colour of red cabbage and radishes to a green, the reddened tincture of
litmus to a purple, and the colour of turmeric and many other yellow
dyes to a brown. Even when combined with carbonic acid, the first three
alkalis exercise this discolouring power, which the alkaline earths,
lime and barytes, do not. The same three alkalis have an acrid, and
somewhat urinous taste; the first two are energetic solvents of animal
matter; and the three combine with oils, so as to form soaps. They unite
with water in every proportion, and also with alcohol; and the first
three combine with water after being carbonated.


ALKALIMETER. An instrument for measuring the alkaline force or purity of
any of the alkalis of commerce. It is founded on the principle, that the
quantity of real alkali present in any sample, is proportional to the
quantity of acid which a given weight of it can neutralize. See the
individual alkalis, POTASH, and SODA.


ALKANA, is the name of the root and leaves of _Lausania inermis_, which
have been long employed in the East, to dye the nails, teeth, hair,
garments, &c. The leaves, ground and mixed with a little limewater,
serve for dyeing the tails of horses in Persia and Turkey.


ALKANET, the root of. (_Anchusa tinctoria._) A species of bugloss,
cultivated chiefly in the neighbourhood of Montpellier. It affords a
fine red colour to alcohol and oils; but a dirty red to water. Its
principal use is for colouring ointments, cheeses, and _pommades_. The
spirituous tincture gives to white marble a beautiful deep stain.


ALLIGATION. An arithmetical formula, useful, on many occasions, for
ascertaining the proportion of constituents in a mixture, when they have
undergone no change of volume by chemical action. When alcoholic liquors
are mixed with water, there is a condensation of bulk, which renders
that arithmetical rule inapplicable. The same thing holds, in some
measure, in the union of metals by fusion. See ALLOY.


ALLOY. (_Alliage_, Fr.; _Legirung_, Germ.) This term formerly signified
a compound of gold and silver, with some metal of inferior value, but it
now means any compound of any two or more metals whatever. Thus, bronze
is an alloy of copper and tin; brass, an alloy of copper and zinc; and
type metal, an alloy of lead and antimony. All the alloys possess
metallic lustre, even when cut or broken to pieces; they are opaque; are
excellent conductors of heat and electricity; are frequently susceptible
of crystallising; are more or less ductile, malleable, elastic, and
sonorous. An alloy which consists of metals differently fusible is
usually malleable in the cold, and brittle when hot, as is exemplified
with brass and gong metal.

Many alloys consist of definite or equivalent proportions of the simple
component metals, though some alloys seem to form in any proportion,
like combinations of salt or sugar with water. It is probable that
peculiar properties belong to the equivalent or atomic ratio, as is
exemplified in the superior quality of brass made in that proportion.

One metal does not alloy indifferently with every other metal, but it is
governed in this respect by peculiar affinities; thus, silver will
hardly unite with iron, but it combines readily with gold, copper, and
lead. In comparing the alloys with their constituent metals, the
following differences may be noted; in general, the ductility of the
alloy is less than that of the separate metals, and sometimes in a very
remarkable degree; on the contrary, the alloy is usually harder than the
mean hardness of its constituents. The mercurial alloys or amalgams are,
perhaps, exceptions to this rule.

The specific gravity is rarely the mean between that of each of its
constituents, but is sometimes greater and sometimes less, indicating,
in the former case, an approximation, and in the latter, a recedure, of
the particles from each other in the act of their union. The following
tables of binary alloys exhibit this circumstance in experimental
detail:--

  Alloys having a density       Alloys having a density
  greater than the mean of      less than the mean of
  their constituents.           their constituents.

  Gold and zinc                 Gold and silver
  Gold and tin                  Gold and iron
  Gold and bismuth              Gold and lead
  Gold and antimony             Gold and copper
  Gold and cobalt               Gold and iridium
  Silver and zinc               Gold and nickel
  Silver and lead               Silver and copper
  Silver and tin                Silver and lead
  Silver and bismuth            Iron and bismuth
  Silver and antimony           Iron and antimony
  Copper and zinc               Iron and lead
  Copper and tin                Tin and lead
  Copper and palladium          Tin and palladium
  Copper and bismuth            Tin and antimony
  Lead and antimony             Nickel and arsenic
  Platinum and molybdenum       Zinc and antimony.
  Palladium and bismuth.

It would be hardly possible to infer the melting point of an alloy from
that of each of its constituent metals; but, in general, the fusibility
is increased by mutual affinity in their state of combination. Of this,
a remarkable instance is afforded in the fusible metal consisting of 8
parts of bismuth, 5 of lead, and 3 of tin, which melts at the heat of
boiling water or 212° Fahr., though the melting point deduced from the
mean of its components should be 514°. This alloy may be rendered still
more fusible by adding a very little mercury to it, when it forms an
excellent material for certain anatomical injections, and for filling
the hollows of carious teeth. Nor do the colours of alloys depend, in
any considerable degree, upon those of the separate metals; thus, the
colour of copper, instead of being rendered paler by a large addition of
zinc, is thereby converted into the rich-looking pinchbeck metal.

By means of alloys, we multiply, as it were, the numbers of useful
metals, and sometimes give usefulness to such as are separately of
little value. Since these compounds can be formed only by fusion, and
since many metals are apt to oxidise readily at their melting
temperature, proper precautions must be taken in making alloys to
prevent this occurrence, which is incompatible with their formation.
Thus, in combining tin and lead, rosin or grease is usually put on the
surface of the melting metals, the carbon produced by the decomposition
of which protects them, in most cases, sufficiently from oxidisement.
When we wish to combine tin with iron, as in the tinning of cast-iron
tea kettles, we rub sal ammoniac upon the surfaces of the hot metals in
contact with each other, and thus exclude the atmospheric oxygen by
means of its fumes. When there is a notable difference in the specific
gravities of the metals which we wish to combine, we often find great
difficulties in obtaining homogeneous alloys; for each metal may tend to
assume the level due to its density, as is remarkably exemplified in
alloys of gold and silver made without adequate stirring of the melting
metals. If the mass be large, and slow of cooling after it is cast in an
upright cylindrical form, the metals sometimes separate, to a certain
degree, in the order of their densities. Thus, in casting large bells
and cannons with copper alloys, the bottom of the casting is apt to
contain too much copper and the top too much tin, unless very dexterous
manipulation in mixing the fused materials have been employed
immediately before the instant of pouring out the melted mass. When such
inequalities are observed, the objects are broken and re-melted, after
which they form a much more homogeneous alloy. This artifice of a double
melting is often had recourse to, and especially in casting the alloys
for the specula of telescopes.

When we wish to alloy three or more metals, we often experience
difficulties, either because one of the metals is more oxidable, or
denser, or more fusible, than the others, or because there is no direct
affinity between two of the metals. In the latter predicament, we shall
succeed better by combining the three metals, first in pairs, for
example, and then melting the two pairs together. Thus, it is difficult
to unite iron with bronze directly; but if, instead of iron, we use tin
plate, we shall immediately succeed, and the bronze, in this manner,
acquires valuable qualities from the iron. Thus, also, to render brass
better adapted for certain purposes, a small quantity of lead ought to
be added to it, but this cannot be done directly with advantage: it is
better to melt the lead first along with the zinc, and then to add this
alloy to the melting copper, or the copper to that alloy, and fuse them
together.

We have said that the difference of fusibility was often an obstacle to
metallic combination; but this circumstance may also be turned to
advantage in decomposing certain alloys by the process called
_eliquation_. By this means silver may be separated from copper, if a
considerable quantity of lead be first alloyed with the said copper;
this alloy is next exposed to a heat just sufficient to melt the lead,
which then sweats out, so to speak, from the pores of the copper, and
carries along with it the greater part of the silver, for which it has a
strong affinity. The lead and the silver are afterwards separated from
each other, in virtue of their very different oxidability, by the action
of heat and air.

One of the alloys most useful to the arts is brass; it is more ductile
and less easily oxidised than even its copper constituent,
notwithstanding the opposite nature of the zinc. This alloy may exist in
many different proportions, under which it has different names, as
tombac, similor, pinchbeck, &c. Copper and tin form, also, a compound of
remarkable utility, known under the names of hard brass, for the bushes,
steps, and bearings of the axles, arbours, and spindles in machinery;
and of bronze, bell-metal, &c. Gold and silver, in their pure state, are
too soft and flexible to form either vessels or coins of sufficient
strength and durability; but when alloyed with a little copper, they
acquire the requisite hardness and stiffness for these and other
purposes.

When we have occasion to unite several pieces of the same or of
different metals, we employ the process called _soldering_, which
consists in fixing together the surfaces by means of an interposed
alloy, which must be necessarily more fusible than the metal or metals
to be joined. That alloy must also consist of metals which possess a
strong affinity for the substances to be soldered together. Hence each
metal would seem to require a particular kind of solder, which is, to a
certain extent, true. Thus, the solder for gold trinkets and plate is an
alloy of gold and silver, or gold and copper; that of silver trinkets,
is an alloy of silver and copper; that of copper is either fine tin, for
pieces that must not be exposed to the fire, or a brassy alloy called
hard solder, of which the zinc forms a considerable proportion. The
solder of lead and tinplate is an alloy of lead and tin, and that of tin
is the same alloy with a little bismuth. Tinning, gilding, and silvering
may also be reckoned a species of alloys, since the tin, gold, and
silver are superficially united in these cases to other metals.

Metallic alloys possess usually more tenacity than could be inferred
from their constituents; thus, an alloy of twelve parts of lead with one
of zinc has a tenacity double that of zinc. Metallic alloys are much
more easily oxidised than the separate metals, a phenomenon which may be
ascribed to the increase of affinity for oxygen which results from the
tendency of the one of the oxides to combine with the other. An alloy of
tin and lead heated to redness takes fire, and continues to burn for
some time like a piece of bad turf.

Every alloy is, in reference to the arts and manufactures, a new metal,
on account of its chemical and physical properties. A vast field here
remains to be explored. Not above sixty alloys have been studied by the
chemists out of many hundred which may be made; and of these very few
have yet been practically employed. Very slight modifications often
constitute very valuable improvements upon metallic bodies. Thus, the
brass most esteemed by turners at the lathe contains from two to three
per cent. of lead; but such brass does not work well under the hammer;
and, reciprocally, the brass which is best under the hammer is too tough
for turning.

That metallic alloys tend to be formed in definite proportions of their
constituents is clear from the circumstance that the native gold of the
auriferous sands is an alloy with silver, in the ratios of 1 atom of
silver united to 4, 5, 6, 12 atoms of gold, but never with a fractional
part of an atom. Also, in making an amalgam of 1 part of silver with 12
or 15 of mercury, and afterwards squeezing the mixture through chamois
leather, the amalgam separates into 2 parts: one, containing a small
proportion of silver and much mercury, passes through the skin; and the
other, formed of 1 of silver and 8 of mercury, is a compound in definite
proportions, which crystallises readily, and remains in the knot of the
bag. An analogous separation takes place in the tinning of mirrors; for
on loading them with the weights, a liquid amalgam of tin is squeezed
out, while another amalgam remains in a solid form composed of tin and
mercury in uniform atomic proportions. But, as alloys are generally
soluble, so to speak, in each other, this definiteness of combination is
masked and disappears in most cases.

M. Chaudet has made some experiments on the means of detecting the
metals of alloys by the cupelling furnace, and they promise useful
applications. The testing depends upon the appearances exhibited by the
metals and their alloys when heated on a cupel. Pure tin, when heated
this way, fuses, becomes of a greyish black colour, fumes a little,
exhibits incandescent points on its surface, and leaves an oxide, which,
when withdrawn from the fire, is at first lemon-yellow, but when cold,
white. Antimony melts, preserves its brilliancy, fumes, and leaves the
vessel coloured lemon-yellow when hot, but colourless when cold, except
a few spots of a rose tint. Zinc burns brilliantly, forming a cone of
oxide; and the oxide, much increased in volume, is, when hot, greenish,
but when cold, perfectly white. Bismuth fumes, becomes covered with a
coat of melted oxide, part of which sublimes, and the rest enters the
pores of the cupel; when cold, the cupel is of a fine yellow colour,
with spots of a greenish hue. Lead resembles bismuth very much; the cold
cupel is of a lemon-yellow colour. Copper melts, and becomes covered
with a coat of black oxide; sometimes spots of a rose tint remain on the
cupel.

Alloys.--Tin 75, antimony 25, melt, become covered with a coat of black
oxide, have very few incandescent points; when cold, the oxide is nearly
black, in consequence of the action of the antimony: a 1/400 part of
antimony may be ascertained in this way in the alloy. An alloy of
antimony, containing tin, leaves oxide of tin in the cupel: a 1/100 part
of tin may be detected in this way. An alloy of tin and zinc gives an
oxide which, whilst hot, is of a green tint, and resembles philosophic
wool in appearance. An alloy containing 99 tin, 1 zinc, did not present
the incandescent points of pure tin, and gave an oxide of greenish tint
when cold. Tin 95, bismuth 5 parts, gave an oxide of a grey colour. Tin
and lead give an oxide of a rusty brown colour. An alloy of lead and
tin, containing only 1 per cent. of the latter metal, when heated, does
not expose a clean surface, like lead, but is covered at times with
oxide of tin. Tin 75, and copper 25, did not melt, gave a black oxide:
if the heat be much elevated, the under part of the oxide is white, and
is oxide of tin; the upper is black, and comes from the copper. The
cupel becomes of a rose colour. If the tin be impure from iron, the
oxide produced by it is marked with spots of a rust colour.

The degree of affinity between metals may be in some measure estimated
by the greater or less facility with which, when of different degrees of
fusibility or volatility, they unite, or with which they can, after
union, be separated by heat. The greater or less tendency to separate
into differently proportioned alloys, by long-continued fusion, may also
give some information upon this subject. Mr. Hatchett remarked, in his
elaborate researches on metallic alloys, that gold made standard with
the usual precautions, by silver, copper, lead, antimony, &c., and then
cast, after long fusion, into vertical bars, was by no means an uniform
compound; but that the top of the bar, corresponding to the metal at the
bottom of the crucible, contained the larger proportion of gold. Hence,
for a more thorough combination, two red-hot crucibles should be
employed, and the liquefied metals should be alternately poured from the
one into the other. To prevent unnecessary oxidisement from the air, the
crucibles should contain, besides the metal, a mixture of common salt
and pounded charcoal. The metallic alloy should also be occasionally
stirred up with a rod of pottery ware.

The most direct evidence of a chemical change having been effected in
alloys is, when the compound melts at a lower temperature than the mean
of its ingredients. Iron, which is nearly infusible, acquires almost the
fusibility of gold when alloyed with this precious metal. The analogy is
here strong with the increase of solubility which salts acquire by
mixture, as is exemplified in the difficulty of crystallising residuums
of saline solutions, or mother waters, as they are called.

In common cases the specific gravity affords a good criterion whereby to
judge of the proportion of two metals in an alloy. But a very fallacious
rule has been given in some respectable works for computing the specific
gravity that should result from the alloying of given quantities of two
metals of known densities, supposing no chemical condensation or
expansion of volume to take place. Thus, it has been taught, that if
gold and copper be united in equal weights, the computed specific
gravity is merely the arithmetical mean between the numbers denoting the
two specific gravities. Whereas, the specific gravity of any alloy must
be computed by dividing the sum of the two weights by the sum of the two
volumes, compared, for conveniency sake, to water reckoned unity. Or, in
another form, the rule may be stated thus:--Multiply the sum of the
weights into the products of the two specific-gravity numbers for a
numerator; and multiply each specific gravity-number into the weight of
the other body, and add the two products together for a denominator. The
quotient obtained by dividing the said numerator by the denominator, is
the truly computed mean specific gravity of the alloy. On comparing with
that density, the density found by experiment, we shall see whether
expansion or condensation of volume has attended the metallic
combination. Gold having a specific gravity of 19·36, and copper of
8·87, when they are alloyed in equal weights, give, by the fallacious
rule of the arithmetical mean of the densities (19·36 + 8·87)/2 = 14·11;
whereas the rightly computed mean density is only 12·16. It is evident
that, on comparing the first result with experiment, we should be led to
infer that there had been a prodigious condensation of volume, though
expansion has actually taken place. Let W, w be the two weights; P, p
the two specific gravities, then M, the mean specific gravity, is given
by the formula--

      (W + w) P p          (P - p)²
  M = ----------- ∴ 2Δ = - -------- =
       P w + p W            P + p

twice the error of the arithmetical mean; which is therefore always in
excess.


ALMOND. (_Amande_, Fr.; _Mandel_, Germ.) There are two kinds of almond
which do not differ in chemical composition, only that the bitter, by
some mysterious reaction of its constituents, generates in the act of
distillation a quantity of a volatile oil, which contains hydrocyanic
acid. Vogel obtained from bitter almonds 8·5 per cent. of husks. After
pounding the kernels, and heating them to coagulate the albumen, he
procured, by expression, 28 parts of an unctuous oil, which did not
contain the smallest particle of hydrocyanic acid. The whole of the oil
could not be extracted in this way. The expressed mass, treated with
boiling water, afforded sugar and gum, and, in consequence of the heat,
some of that acid. The sugar constitutes 6·5 per cent. and the gum 3.
The vegetable albumen extracted, by means of caustic potash, amounted to
30 parts: the vegetable fibre to only 5. The poisonous aromatic oil,
according to Robiquet and Boutron-Charlard, does not exist ready-formed
in the bitter almond, but seems to be produced under the influence of
ebullition with water. These chemists have shown that bitter almonds
deprived of their unctuous oil by the press, when treated first by
alcohol, and then by water, afford to neither of these liquids any
volatile oil. But alcohol dissolves out a peculiar white crystalline
body, without smell, of a sweetish taste at first, and afterwards
bitter, to which they gave the name of _amygdaline_. This substance does
not seem convertible into volatile oil.

Sweet almonds by the analysis of Boullay, consist of 54 parts of the
bland almond oil, 6 of uncrystallisable sugar, 3 of gum, 24 of vegetable
albumen, 24 of woody fibre, 5 of husks, 3·5 of water, 0·5 of acetic
acid, including loss. We thus see that sweet almonds contain nearly
twice as much oil as bitter almonds do.


ALMOND OIL. A bland fixed oil, obtained usually from bitter almonds by
the action of a hydraulic press, either in the cold, or aided by hot
iron plates. See OIL.


ALOE. A series of trials has been made within a few years at Paris to
ascertain the comparative strength of cables made of hemp and of the
aloe from Algiers; and they are said to have all turned to the advantage
of the aloe. Of cables of equal size, that made of aloe raised a weight
of 2,000 kilogrammes (2 tons nearly); that made of hemp, a weight of
only 400 kilogrammes. At the exposition of objects of national industry,
two years ago, in Brussels, I saw aloe cordage placarded, as being far
preferable to hempen. See ROPE.


ALUDEL. A pear-shaped vessel open at either end, of which a series are
joined for distilling mercury in Spain. See MERCURY.


ALUM. (_Alun_, Fr.; _Alaum_, Germ.) A saline body, consisting of the
earth of clay, called alumina by the chemists, combined with sulphuric
acid and potash, or sulphuric acid and ammonia, into a triple compound.
It occurs in the crystallised form of octahedrons, has an acerb subacid
taste, and reddens the blue colour of litmus or red cabbage.

Alum works existed many centuries ago at Roccha, formerly called Edessa,
in Syria, whence the ancient name of Roch alum given to this salt. It
was afterwards made at Foya Nova, near Smyrna, and in the neighbourhood
of Constantinople. The Genoese, and other trading people of Italy,
imported alum from these places into western Europe, for the use of the
dyers of red cloth. About the middle of the fifteenth century, alum
began to be manufactured at La Tolfa, Viterbo, and Volaterra, in Italy;
after which time the importation of oriental alum was prohibited by the
pope, as detrimental to the interests of his dominions. The manufacture
of this salt was extended to Germany at the beginning of the sixteenth
century, and to England at a somewhat later period, by Sir Thomas
Chaloner, in the reign of Elizabeth. In its pure state, it does not seem
to have been known to the ancients; for Pliny, in speaking of something
like plumose alum, says, that it struck a black colour with pomegranate
juice, which shows that the green vitriol was not separated from it. The
_stypteria_ of Dioscorides, and the _alumen_ of Pliny, comprehended,
apparently, a variety of saline substances, of which sulphate of iron,
as well as alumina, was probably a constituent part. Pliny, indeed,
says, that a substance called in Greek Ὑγρα, or watery, probably from
its very soluble nature, which was milk-white, was used for dyeing wool
of bright colours. This may have been the mountain butter of the German
mineralogists, which is a native sulphate of alumina, of a soft texture,
waxy lustre, and unctuous to the touch.

The only alum manufactories now worked in Great Britain, are those of
Whitby, in England, and of Hurlett and Campsie, near Glasgow, in
Scotland; and these derive the acid and earthy constituents of the salt
from a mineral called alum slate. This mineral has a bluish or
greenish-black colour, emits sulphurous fumes when heated, and acquires
thereby an aluminous taste. The alum manufactured in Great Britain
contains potash as its alkaline constituent; that made in France
contains, commonly, ammonia, either alone, or with variable quantities
of potash. Alum may in general be examined by water of ammonia, which
separates from its watery solutions its earthy basis, in the form of a
light flocculent precipitate. If the solution be dilute, this
precipitate will float long as an opalescent cloud.

If we dissolve alum in 20 parts of water, and drop this solution slowly
into water or caustic ammonia till this be nearly, but not entirely,
saturated, a bulky white precipitate will fall down, which, when
properly washed with water, is pure aluminous earth or clay, and dried
forms 10·82 per cent. of the weight of the alum. If this earth, while
still moist, be dissolved in dilute sulphuric acid, it will constitute,
when as neutral as possible, the sulphate of alumina, which requires
only two parts of cold water for its solution. If we now decompose this
solution, by pouring into it water of ammonia, there appears an
insoluble white powder, which is subsulphate of alumina, or basic alum;
and contains three times as much earth as exists in the neutral
sulphate. If, however, we pour into the solution of the neutral sulphate
of alumina a solution of sulphate of potash, a white powder will fall if
the solutions be concentrated, which is true _alum_; but if the
solutions be dilute, by evaporating their mixture, and cooling it,
crystals of alum will be obtained.

When newly precipitated alumina is boiled in a solution of alum, a
portion of the earth enters into combination with the salt, constituting
an insoluble compound, which falls in the form of a white powder. The
same combination takes place, if we decompose a boiling hot solution of
alum with a solution of potash, till the mixture appears nearly neutral
by litmus paper. This insoluble or basic alum exists native in the
alum-stone of Tolfa, near Civita Vecchia, and it consists in 100 parts
of 19·72 parts of sulphate of potash, 61·99 basic sulphate of alumina,
and 18·29 water. When this mineral is treated with a due quantity of
sulphuric acid, it dissolves, and is converted into the crystallisable
alum of commerce.

These experimental facts develope the principles of the manufacture of
alum, which is prosecuted under various modifications, for its important
uses in the arts. Alum seldom occurs ready-formed in nature;
occasionally, as an efflorescence on stones, and in certain mineral
waters in the East Indies. The alum of European commerce is fabricated
artificially, either from the alum schists or stones, or from clay. The
mode of manufacture differs according to the nature of these earthy
compounds. Some of them, such as the alum stone, contain all the
elements of the salt, but mixed with other matters, from which it must
be freed. The schists contain only the elements of two of the
constituents, namely, clay and sulphur, which are convertible into
sulphate of alumina, and this may be then made into alum by adding the
alkaline ingredient. To this class belong the alum slates, and other
analogous schists, containing brown coal.

1. _Manufacture of Alum from the Alum Stone._--The alum-stone is a rare
mineral, being found in moderate quantity at Tolfa, and in larger in
Hungary, at Bereghszasz, and Muszag, where it forms entire beds in a
hard substance, partly characterised by numerous cavities, containing
drusy crystallisations of alum-stone or basic alum. The larger lumps
contain more or fewer flints disseminated through them, and are,
according to their quality, either picked out to make alum, or are
thrown away. The sorted pieces are roasted or calcined, by which
operation apparently the hydrate of alumina, associated with the
sulphate of alumina, loses its water, and, as burnt clay, loses its
affinity for alum. It becomes, therefore, free; and during the
subsequent exposure to the weather the stone gets disintegrated, and the
alum becomes soluble in water.

The calcination is performed in common lime-kilns in the ordinary way.
In the regulation of the fire it is requisite, here, as with gypsum, to
prevent any fusion or running together of the stones, or even any
disengagement of sulphuric or sulphurous acids, which would cause a
corresponding defalcation in the product of alum. For this reason the
contact of the ignited stones with carbonaceous matter ought to be
avoided.

The calcined alum-stones, piled in heaps from 2 to 3 feet high, are to
be exposed to the weather, and meanwhile they must be continually kept
moist by sprinkling them with water. As the water combines with the alum
the stones crumble down, and fall, eventually, into a pasty mass, which
must be lixiviated with warm water, and allowed to settle in a large
cistern. The clear supernatant liquor, being drawn off, must be
evaporated, and then crystallised. A second crystallisation finishes the
process, and furnishes a marketable alum. Thus the Roman alum is made,
which is covered with a fine red film of peroxide of iron.

2. _Alum Manufacture from Alum Schist._--The greater portion of the alum
found in British commerce is made from alum-slate and analogous
minerals. This slate contains more or less iron pyrites, mixed with
coaly or bituminous matter, which is occasionally so abundant as to
render them somewhat combustible. In the strata of brown coal and
bituminous wood, where the upper layers lie immediately under clay beds,
they consist of the coaly substance rendered impure with clay and
pyrites. This triple mixture constitutes the essence of all good alum
schists, and it operates spontaneously towards the production of
sulphate of alumina. The coal serves to make the texture open, and to
allow the air and moisture to penetrate freely, and to change the
sulphur and iron present into acid and oxide. When these schists are
exposed to a high temperature in contact with air, the pyrites loses one
half of its sulphur, in the form of sublimed sulphur or sulphurous acid,
and becomes a black sulphuret of iron, which speedily attracts oxygen,
and changes to sulphate of iron, or green vitriol. The brown coal
schists contain, commonly, some green vitriol crystals spontaneously
formed in them. The sulphate of iron transfers its acid to the clay,
progressively, as the iron, by the action of the air with a little
elevation of temperature, becomes peroxidised; whereby sulphate of
alumina is produced. A portion of the green vitriol remains, however,
undecomposed, and so much the more as there may happen to be less of
other salifiable bases present in the clay slate. Should a little
magnesia or lime be present, the vitriol gets more completely
decomposed, and a portion of Epsom salt and gypsum is produced.

The manufacture of alum from alum schists may be distributed under the
six following heads:--1. The preparation of the alum slate. 2. The
lixiviation of the slate. 3. The evaporation of the lixivium. 4. The
addition of the saline ingredients, or the precipitation of the alum. 5.
The washing of the aluminous salts; and 6. The crystallisation.

1. _Preparation of the Alum Slate._--Some alum slates are of such a
nature that, being piled in heaps in the open air, and moistened from
time to time, they get spontaneously hot, and by degrees fall into a
pulverulent mass, ready to be lixiviated. The greater part, however,
require the process of ustulation, from which they derive many
advantages. The cohesion of the dense slates is thereby so much impaired
that their decomposition becomes more rapid; the decomposition of the
pyrites is quickened by the expulsion of a portion of the sulphur; and
the ready-formed green vitriol is partly decomposed by the heat, with a
transference of its sulphuric acid to the clay, and the production of
sulphate of alumina.

Such alum-slates as contain too little bitumen or coal for the roasting
process must be interstratified with layers of small coal or brushwood
over an extensive surface. At Whitby the alum rock, broken into small
pieces, is laid upon a horizontal bed of fuel, composed of brushwood;
but at Hurlett small coal is chiefly used for the lower bed. When about
four feet of the rock is piled on, fire is set to the bottom in various
parts; and whenever the mass is fairly kindled, more rock is placed over
the top. At Whitby this piling process is continued till the calcining
heap is raised to the height of 90 or 100 feet. The horizontal area is
also augmented at the same time till it forms a great bed nearly 200
feet square, having therefore about 100,000 yards of solid measurement.
The rapidity of the combustion is tempered by plastering up the crevices
with small schist moistened. When such an immense mass is inflamed, the
heat is sure to rise too high, and an immense waste of sulphur and
sulphuric acid must ensue. This evil has been noticed at the Whitby
works. At Hurlett the height to which the heap is piled is only a few
feet, while the horizontal area is expanded; which is a much more
judicious arrangement. At Whitby 130 tons of calcined schist produce on
an average 1 ton of alum. In this humid climate it would be advisable to
pile up on the top of the horizontal strata of brushwood or coal, and
schist, a pyramidal mass of schist, which having its surface plastered
smooth, with only a few air-holes, will protect the mass from the rains,
and at the same time prevent the combustion from becoming too vehement.
Should heavy rains supervene, a gutter must be scooped out round the
pile for receiving the aluminous lixivium, and conducting it into the
reservoir.

It may be observed, that certain alum schists contain abundance of
combustible matter, to keep up a suitable calcining heat after the fire
is once kindled; and therefore nothing is needed but the first layer of
brushwood, which, in this case, may be laid over the first bed of the
bituminous schist.

A continual, but very slow, heat, with a smothered fire, is most
beneficial for the ustulation of alum slate. When the fire is too brisk,
the sulphuret of iron may run with the earthy matters into a species of
slag, or the sulphur will be dissipated in vapour, by both of which
accidents the product of alum will be impaired. Those bituminous alum
schists which have been used as fuel under steam boilers have suffered
such a violent combustion that their ashes yield almost no alum. Even
the best regulated calcining piles are apt to burn too briskly in high
winds, and should have their draught-holes carefully stopped under such
circumstances. It may be laid down as a general rule, that the slower
the combustion the richer the roasted ore will be in sulphate of
alumina. When the calcination is complete, the heap diminishes to one
half its original bulk; it is covered with a light reddish ash, and is
open and porous in the interior, so that the air can circulate freely
throughout the mass. To favour this access of air, the masses should not
be too lofty; and in dry weather a little water should be occasionally
sprinkled on them, which, by dissolving away some of the saline matter,
will make the interior more open to the atmosphere.

When the calcined mineral becomes thoroughly cold, we may proceed to the
lixiviation. But as, from the first construction of the piles or beds
till their complete calcination, many weeks, or even months, may elapse,
care ought to be taken to provide a sufficient number or extent of them,
so as to have an adequate supply of material for carrying on the
lixiviating and crystallising processes during the course of the year,
or at least during the severity of the winter season, when the
calcination may be suspended, and the lixiviation becomes
unsatisfactory. The beds are known to be sufficiently decomposed by the
efflorescence of the salt which appears upon the stones, from the strong
aluminous taste of the ashes, and from the appropriate chemical test of
lixiviating an aliquot average portion of the mass, and seeing how much
alum it will yield to solution of muriate or sulphate of potash.

2. _The Lixiviation._--The lixiviation is best performed in stone-built
cisterns; those of wood, however strong at first, are soon decomposed,
and need repairs. They ought to be erected in the neighbourhood of the
calcining heaps, to save the labour of transport, and so arranged that
the solutions from the higher cisterns may spontaneously flow into the
lower. In this point of view, a sloping terrace is the best situation
for an alum work. In the lowest part of this terrace, and in the
neighbourhood of the boiling-house, there ought to be two or more large
deep tanks, for holding the crude lixivium, and they should be protected
from the rain by a proper shed. Upon a somewhat higher level the
cisterns of the clear lixivium may be placed. Into the highest range of
cisterns the calcined mineral is to be put, taking care to lay the
largest lumps at the bottom, and to cover them with lighter ashes. A
sufficient quantity of water is now to be run over it, and allowed to
rest for some time. The lixivium may then be drawn off, by a stopcock
connected with a pipe at the bottom of the cistern, and run into another
cistern at a somewhat lower level. Fresh water must now be poured on the
partly exhausted schist, and allowed to remain for a sufficient time.
This lixivium, being weak, should be run off into a separate tank. In
some cases a third addition of fresh water may be requisite, and the
weak lixivium which is drawn off may be reserved for a fresh portion of
calcined mineral. In order to save evaporation, it is always requisite
to strengthen weak leys by employing them instead of water for fresh
portions of calcined schist. Upon the ingenious disposition and form of
these lixiviating cisterns much of the economy and success of an alum
work depend. The hydrometer should be always used to determine the
degree of concentration which the solutions acquire.

The lixiviated stone being thus exhausted of its soluble ingredients, is
to be removed from the cisterns, and piled up in a heap in any
convenient place, where it may be left either spontaneously to
decompose, or, after drying, may be subjected to another calcination.

The density of the solution may be brought, upon an average, up to the
sp. gr. of from 1·09 to 1·15. The latter density may always be obtained
by pumping up the weaker solutions upon fresh calcined _mine_. This
strong liquor is then drawn off, when the sulphate of lime, the oxide of
iron, and the earths are deposited. It is of advantage to leave the
liquor exposed for some time, whereby the green vitriol may pass into a
persulphate of iron with the deposition of some oxide, while the
liberated acid may combine with some of the clay present, so as to
increase the quantity of sulphate of alumina. The manufacture of alum is
the more imperfect, as the quantity of sulphate of iron left
undecomposed is greater, and therefore every expedient ought to be tried
to convert the sulphate of iron into sulphate of alumina.

3. _The evaporation of the Schist Lixivium._--As the aluminous liquors,
however well settled at first, are apt, on the great scale, to deposit
earthy matters in the course of their concentration by heat, they are
best evaporated by a surface fire, such as that employed at Hurlett and
Campsie. A water-tight stone cistern must be built, having a layer of
well rammed clay behind the flags or tiles which line its bottom and
sides. This cistern may be 4 or 6 feet wide, 2 or 3 feet deep, and 30 or
40 feet long, and it is covered in by an arch of stone or brickwork. At
one extremity of this tunnel, or covered canal, a fire-grate is set, and
at the other a lofty chimney is erected. The cistern being filled to the
brim with the alum ley, a strong fire is kindled in the reverberatory
grate, and the flame and hot air are forced to sweep along the surface
of the liquor, so as to keep it in constant ebullition, and to carry off
the aqueous parts in vapour. The soot which is condensed in the process
falls to the bottom, and leaves the body of the liquor clear. As the
concentration goes on, more of the rough lixivium is run in from the
settling cistern, placed on a somewhat higher level, till the whole gets
charged with a clear liquor of a specific gravity sufficiently high for
transferring into the proper lead boilers.

At Whitby, the lead pans are 10 feet long, 4 feet 9 inches wide, 2 feet
2 inches deep at the one end, and 2 feet 8 inches deep at the other.
This increase of depth and corresponding slope, facilitates the
decantation of the concentrated lixivium by means of a syphon, applied
at the lower end. The bottom of the pan is supported by a series of
parallel iron bars, placed very near each other. In these lead pans the
liquor is concentrated, at a brisk boiling heat, by means of the flame
of a flue beneath them. Every morning the pans are emptied into a
settling cistern of stone or lead. The specific gravity of the liquor
should be about 1·4 or 1·5, being a saturated solution of the saline
matters present. The proper degree of density must vary, however, with
different kinds of lixivia, and according to the different views of the
manufacturer. For a liquor which consists of two parts of sulphate of
alumina, and one part of sulphate of iron, a specific gravity of 1·25
may be sufficient; but for a solution which contains two parts of
sulphate of iron to one of sulphate of alumina, so that the green
vitriol must be withdrawn first of all by crystallisation, a specific
gravity of 1·4 may be requisite.

The construction of an evaporating furnace well adapted to the
concentration of aluminous and other crude lixivia, is described under
SODA. The liquor basin may be made of tiles or flags puddled in clay,
and secured at the seams with a good _hydraulic_ cement. A mortar made
of quicklime mixed with the exhausted schist in powder, and iron
turnings, is said to answer well for this purpose. Sometimes over the
reverberatory furnace a flat pan is laid, instead of the arched top,
into which the crude liquor is put for neutralisation and partial
concentration. In Germany, such a pan is made of copper, because iron
would waste too fast, and lead would be apt to melt. From this
preparation basin the under evaporating trough is gradually supplied
with hot liquor. At one side of this lower trough, there is sometimes a
door, through which the sediment may be raked out as it accumulates upon
the bottom. Such a contrivance is convenient for this mode of
evaporation, and it permits, also, any repairs to be readily made; but,
indeed, an apparatus of this kind, well mounted at first, will serve for
many years.

In the course of the final concentration of the liquors, it is customary
to add some of the mother waters of a former process, the quantity of
which must be regulated by a proper analysis and knowledge of their
contents. If these mother waters contain much free sulphuric acid, from
the peroxidation of their sulphate of iron, they may prove useful in
dissolving a portion of the alumina of the sediment which is always
present in greater or less quantity.

4. _The precipitation of the Alum by adding Alkaline Salts._--As a
general rule, it is most advantageous to separate, first of all, from
the concentrated clear liquors, the alum in the state of powder or small
crystals, by addition of the proper alkaline matter, and to leave the
mingled foreign salts, such as the sulphate of iron or magnesia, in
solution, instead of trying to abstract these salts by a previous
crystallisation. In this way we not only simplify and accelerate the
manufacture of alum, and leave the mother waters to be worked up at any
convenient season, but we also avoid the risk of withdrawing any of the
sulphate of alumina with the sulphate of iron or magnesia. On this
account, the concentration of the liquor ought not to be pushed so far
as that, when it gets cold, it should throw out crystals, but merely to
the verge of this point. This density may be determined by suitable
experiments.

The clear liquor should now be run off into the precipitation cistern,
and have the proper quantity of sulphate or muriate of potash, or impure
sulphate or carbonate of ammonia added to it. The sulphate of potash,
which is the best precipitant, forms 18·34 parts out of 100 of
crystallised alum; and therefore that quantity of it, or its equivalent
in muriate of potash, or other potash or ammoniacal salts, must be
introduced into the aluminous liquor. Since sulphate of potash takes 10
parts of cold water to dissolve it, but is much more soluble in boiling
water, and since the precipitation of alum is more abundant the more
concentrated the mingled solutions are, it would be prudent to add the
sulphate solution as hot as may be convenient; but, as muriate of potash
is fully three times more soluble in cold water, it is to be preferred
as a precipitant, when it can be procured at a cheap rate. It has, also,
the advantage of decomposing the sulphate of iron present into a
muriate, a salt very difficult of crystallisation, and, therefore, less
apt to contaminate the crystals of alum. The quantity of alkaline salts
requisite to precipitate the alum, in a granular powder, from the
lixivium, depends on their richness in potash or ammonia, on the one
hand, and on the richness of the liquors in sulphate of alumina on the
other; and it must be ascertained, for each large quantity of product,
by a preliminary experiment in a precipitation glass. Here, an aliquot
measure of the aluminous liquor being taken, the liquid precipitant must
be added in successive portions, as long as it causes any cloud, when
the quantity added will be indicated by the graduation of the vessel. A
very exact approximation is not practicable upon the great scale; but,
as the mother waters are afterwards mixed together in one cistern, any
excess of the precipitant, at one time, is corrected by excess of
aluminous sulphate at another, and the resulting alum meal is collected
at the bottom. When the precipitated saline powder is thoroughly settled
and cooled, the supernatant mother water must be drawn off by a pump, or
rather a syphon or stopcock, into a lower cistern. The more completely
this drainage is effected, the more easily and completely will the alum
be purified.

This mother liquor has, generally, a specific gravity of 1·4 at a medium
temperature of the atmosphere, and consists of a saturated solution of
sulphate or muriate of black and red oxide of iron, with sulphate of
magnesia, in certain localities, and muriate of soda, when the soaper’s
salt has been used as a precipitant, as also a saturated solution of
sulphate of alumina. By adding some of it, from time to time, to the
fresh lixivia, a portion of that sulphate is converted into alum; but,
eventually, the mother water must be evaporated, so as to obtain from it
a crop of ferruginous crystals; after which it becomes capable, once
more, of giving up its alum to the alkaline precipitants.

When the aluminous lixivia contain a great deal of sulphate of iron, it
may be good policy to withdraw a portion of it by crystallisation before
precipitating the alum. With this view, the liquors must be evaporated
to the density of 1·4, and then run off into crystallising stone
cisterns. After the green vitriol has concreted, the liquor should be
pumped back into the evaporating pan, and again brought to the density
of 1·4. On adding to it, now, the alkaline precipitants, the alum will
fall down from this concentrated solution, in a very minute crystalline
powder, very easy to wash and purify. But this method requires more
vessels and manipulation than the preceding, and should only be had
recourse to from necessity; since it compels us to carry on the
manufacture of both the valuable alum and the lower priced salts at the
same time; moreover, the copperas extracted at first from the schist
liquors carries with it, as we have said, a portion of the sulphate of
alumina, and acquires thereby a dull aspect; whereas the copperas
obtained after the separation of the alum is of a brilliant appearance.

5. _The washing, or edulcoration, of the Alum Powder._--This crystalline
pulverulent matter has a brownish colour, from the admixture of the
ferruginous liquors; but it may be freed from it by washing with very
cold water, which dissolves not more than one sixteenth of its weight of
alum. After stirring the powder and the water well together, the former
must be allowed to settle, and then the washing must be drawn off. A
second washing will render the alum nearly pure. The less water is
employed, and the more effectually it is drained off, the more complete
is the process. The second water may be used in the first washing of
another portion of alum powder, in the place of pure water. These
washings may be added to the schist lixivia.

6. _The crystallisation._--The washed alum is put into a lead pan, with
just enough water to dissolve it at a boiling heat; fire is applied, and
the solution is promoted by stirring. Whenever it is dissolved in a
saturated state, it is run off into the crystallising vessels, which are
called _roching_ casks. These casks are about five feet high, three feet
wide in the middle, somewhat narrower at the ends; they are made of very
strong staves, nicely fitted to each other, and held together by strong
iron hoops, which are driven on _pro tempore_, so that they may be
easily knocked off again, in order to take the staves asunder. The
concentrated solution, during its slow cooling in these close vessels,
forms large regular crystals, which hang down from the top, and project
from the sides, while a thick layer or cake lines the whole interior of
the cask. At the end of eight or ten days, more or less, according to
the weather, the hoops and staves are removed, when a cask of apparently
solid alum is disclosed to view. The workman now pierces this mass with
a pickaxe at the side near the bottom, and allows the mother water of
the interior to run off on the sloping stone floor into a proper
cistern, whence it is taken and added to another quantity of washed
powder to be crystallised with it. The alum is next broken into lumps,
exposed in a proper place to dry, and is then put into the finished bing
for the market. There is sometimes a little insoluble basic alum
(subsulphate) left at the bottom of the cask. This being mixed with the
former mother liquors, gets sulphuric acid from them; or, being mixed
with a little sulphuric acid, it is equally converted into alum.

When, instead of potash or its salts, the ammoniacal salts are used, or
putrid urine, with the aluminous lixivia, ammoniacal alum is produced,
which is perfectly similar to the potash alum in its appearance and
properties. At a gentle heat both lose their water of crystallisation,
amounting to 45-1/2 per cent. for the potash alum, and 48 for the
ammoniacal. The quantity of acid is the same in both, as, also, very
nearly the quantity of alumina, as the following analyses will show:

           Potash alum.                        Ammonia alum.

  Sulphate of potash            18·34 Sulphate of ammonia          12·88
  Sulphate of alumina           36·20 Sulphate of alumina          38·64
  Water                         45·46 Water                        48·48
                               ------                             ------
                               100·00                             100·00
                               ------                             ------

      Or otherwise, Potash alum.              Ammonia alum.

   1 atom sulphate of potash  1089·07  1 atom sulphate of ammonia  716·7
   1                  alumina 2149·80  1                  alumina 2149·8
  24 water                    2669·52 24 water                    2699·5
                              -------                             ------
                              5938·39                             5566·0
                              -------                             ------

           Or, Potash alum.                   Ammonia alum.

  Alumina                       10·82 Alumina                      11·90
  Potash                         9·94 Ammonia                       3·89
  Sulphuric Acid                33·77 Sulphuric acid               36·10
  Water                         45·47 Water                        48·11
                               ------                             ------
                               100·00                             100·00
                               ------                             ------

When heated pretty strongly, the ammoniacal alum loses its sulphuric
acid and ammonia, and only the earth remains. This is a very convenient
process for procuring pure alumina. Ammoniacal alum is easily
distinguished from the other by the smell of ammonia which it exhales
when triturated with quicklime. The Roman alum, made from alum stone,
possesses most of the properties of the schist-made alums, but it has a
few peculiar characters: it crystallises always in opaque cubes, whereas
the common alum crystallises in transparent octahedrons. It is probable
that Roman alum is a sulphate of alumina and potash, with a slight
excess of the earthy ingredient. It is permanent when dissolved in cold
water; for after a slow evaporation it is recovered in a cubical form.
But when it is dissolved in water heated to 110° Fahr. and upwards, or
when its solution is heated above this pitch, subsulphate of alumina
falls, and on evaporation octahedral crystals of common alum are
obtained. The exact composition of the Roman alum has not been
determined, as far as I know. It probably differs from the other also in
its water of crystallisation. The Roman alum contains, according to MM.
Thenard and Roard, only 1/2200 of sulphate of iron, while the common
commercial alums contain 1/1000. It may be easily purified by solution,
granulation, crystallisation, and washing, as has been already
explained.

Alum is made extensively in France from an artificial sulphate of
alumina. For this purpose clays are chosen as free as possible from
carbonate of lime and oxide of iron. They are calcined in a
reverberatory furnace, in order to expel the water, to peroxidise the
iron, and to render the alumina more easily acted on by the acid. The
expulsion of the water renders the clay porous and capable of absorbing
the sulphuric acid by capillary attraction. The peroxidation of the iron
renders it less soluble in the sulphuric acid; and the silica of the
clay, by reacting on the alumina, impairs its aggregation, and makes it
more readily attracted by the acid. The clay should, therefore, be
moderately calcined; but not so as to indurate it like pottery ware, for
it would then suffer a species of siliceous combination which would make
it resist the action of acids. The clay is usually calcined in a
reverberatory furnace, the flame of which serves thereafter to heat two
evaporating pans and a basin for containing a mixture of the calcined
clay and sulphuric acid. As soon as the clay has become friable in the
furnace it is taken out, reduced to powder, and passed through a fine
sieve. With 100 parts of the pulverised clay, 45 parts of sulphuric
acid, of sp. gr. 1·45, are well mixed, in a stone basin, arched over
with brickwork. The flame and hot air of a reverberatory furnace are
made to play along the mixture, in the same way as described for
evaporating the schist liquors. See SODA. The mixture, being stirred
from time to time, is, at the end of a few days, to be raked out, and to
be set aside in a warm place, for the acid to work on the clay, during
six or eight weeks. At the end of this time it must be washed, to
extract the sulphate of alumina. With this view, it may be treated like
the roasted alum ores above described. If potash alum is to be formed,
this sulphate of alumina is evaporated to the specific gravity of 1·38;
but if ammonia alum, to the specific gravity of only 1·24; because the
sulphate of ammonia, being soluble in twice its weight of water, will
cause a precipitation of pulverulent alum from a weaker solution of
sulphate of alumina than the less soluble sulphate of potash could do.

The alum stone, from which the Roman alum is made, contains potash. The
following analysis of _alunite_, by M. Cordier, places this fact in a
clear light:--

  Sulphate of potash       18·53
  Sulphate of alumina      38·50
  Hydrate of alumina       42·97
                          ------
                          100·00
                          ------

To transform this compound into alum, it is merely necessary to abstract
the hydrate of alumina. The ordinary alum stone, however, is rarely so
pure as the above analysis would seem to show; for it contains a mixture
of other substances; and the above are in different proportions.

Alum is very extensively employed in the arts, most particularly in
dyeing, lake making, dressing sheep-skins, pasting paper, in clarifying
liquors, &c. Its purity for the dyer may be tested by prussiate of
potash, which will give solution of alum a blue tint in a few minutes if
it contain even a very minute portion of iron. A bit of nut-gall is also
a good test of iron.


AMADOU. The French name of the spongy combustible substance, called in
German _zunderschwamm_, prepared from a species of agaric, the _boletus
igniarius_, a kind of mushroom, which grows on the trunks of old oaks,
ashes, beeches, &c. It must be plucked in the months of August and
September. It is prepared by removing the outer bark with a knife, and
separating carefully the spongy substance of a yellow brown colour,
which lies within it, from the ligneous matter below. This substance is
cut into thin slices, and beat with a mallet to soften it, till it can
be easily pulled asunder between the fingers. In this state the
_boletus_ is a valuable substance for stopping oozing hemorrhages, and
some other surgical purposes. To convert it into tinder it must receive
a finishing preparation, which consists in boiling it in a strong
solution of nitre; drying it, beating it anew, and putting it a second
time into the solution. Sometimes, indeed, to render it very
inflammable, it is imbued with gunpowder, whence the distinction of
black and brown amadou.

All the puff balls of the lycopodium genus of plants, which have a
fleshy or filamentous structure, yield a tinder quite ready for soaking
in gunpowder water. The Hindoos employ a leguminous plant, which they
call _solu_, for the same purpose. Its thick spongy stem, being reduced
to charcoal, takes fire like amadou.


AMALGAM. When mercury is alloyed with any metal, the compound is called
an amalgam of that metal; as, for example, an amalgam of tin, bismuth,
&c.


AMALGAMATION. This is a process used extensively in extracting silver
and gold from certain of their ores, founded on the property which
mercury has to dissolve these metals as disseminated in the minerals,
and thus to separate them from the earthy matters. See MERCURY,
METALLURGY, and SILVER.


AMBER. (_Succin_, Fr.; _Bernstein_, Germ.) A mineral solid, of a yellow
colour of various shades, which burns quite away with flame, and
consists of carbon, hydrogen, and oxygen, in nearly the same
proportions, and the same state of combination, as vegetable resin. Its
specific gravity varies, by my trials, from 1·080 to 1·085. It becomes
negatively and powerfully electrical by friction. When applied to a
lighted candle it takes fire, swells considerably, and exhales a white
smoke of a pungent odour; but does not run into drops. Copal, which
resembles it in several respects, differs in being softer, and in
melting into drops at the flame; and mellite, or honey-stone, which is a
mineral of a similar colour, becomes white when laid on a red-hot coal.

The texture of amber is resino-vitreous, its fracture conchoidal, and
lustre glassy. It is perfectly homogeneous; sufficiently hard to scratch
gypsum, and to take a fine polish. It is, however, scratched by
calcareous spar. When amber is distilled in a retort, crystalline
needles of succinic acid sublime into the dome, and oil of amber drops
from the beak into the receiver. Fossil resins, such as that of
Highgate, found in the London clay formation, do not afford succinic
acid by heat; nor does copal. Amber is occasionally found of a whitish
and brownish colour.

The most interesting fact relative to this vegeto-mineral is its
geological position, which is very characteristic and well determined.
It is found almost uniformly in separate nodules, disseminated in the
sand, clay, or fragments of lignite of the plastic clay, and lignite
formation, situated between the _calcaire grossier_ (crag limestone) of
the tertiary strata above, and the white chalk below. The size of these
nodules varies from a nut to a man’s head; but this magnitude is very
rare in true amber. It does not occur either in continuous beds, like
the chalk flints, nor in veins; but it lies at one time in the earthy or
friable strata, which accompany or include the lignites; at another,
entangled in the lignites themselves; and is associated with the
minerals which constitute this formation, principally the pyrites, the
most abundant of all. The pieces of amber found in the sands, and other
formations evidently alluvial, those met with on the sea-coasts of
certain countries, and especially Pomerania, come undoubtedly from the
above geological formation; for the organic matters found still adhering
to the amber leave no doubt as to its primitive place. Amber does not,
therefore, belong to any postdiluvian or modern soil, since its native
bed is covered by three or four series of strata, often of considerable
thickness, and well characterised; proceeding upwards from the plastic
clay which includes the amber: these are, the crag limestone, the bone
gypsum, with its marls, the marly limestone, the upper marl sandstone,
which covers it, and, lastly, the freshwater or lacustrine formation,
often so thick, and composed of calcareous and siliceous rocks.

The amber bed is not, however, always covered with all these strata; and
it is even rare to see a great mass of one of them above the ground
which contains it; because, were it buried under such strata, it would
be difficult to meet with such circumstances as would lay it
spontaneously open to the day. But by comparing observations made in
different places, relatively to the patches of these formations, which
cover the amber deposits, we find that no other mineral formations have
been ever seen among them except those above detailed, and thus learn
that its geological locality is completely determined.

The proper yellow amber, therefore, or the Borussic, from the country
where it has been most abundantly found, belongs to the plastic clay
formation, intermediate, in England, between the chalk and the London
clay. It is sometimes interposed in thin plates between the layers of
the lignites, but more towards the bark of the fibrous lignites, which
retain the form of the wood, than towards the middle of the trunk of the
tree; a position analogous to that of the resinous matters in our
existing ligneous vegetables. The fibrous lignites which thus contain
amber belong to the dicotyledinous woods. Hence that substance seems to
have been formed during the life of the vegetable upon which it is now
encrusted. It must be remembered that the grounds containing the amber
are often replete with the sulphates of iron, alumina, and lime, or at
least with the pyritous elements of these salts. Some specimens of amber
have a surface figured with irregular meshes, indicating a sort of
shrinkage from consolidation, and consequently a matter that was at one
time fluid, viscid, or merely soft. From optical examination, Dr.
Brewster has concluded amber to be of vegetable origin.

The different bodies included in the amber, distinguishable from its
transparence, demonstrate, indeed, in the most convincing manner, its
primitive state of liquidity or softness. These bodies have long
exercised the skill of naturalists. They are generally insects, or
remains of insects, and sometimes leaves, stalks, or other portions of
vegetables. Certain families of insects occur more abundantly than
others. Thus the _hymenoptera_, or insects with four naked membranaceous
wings, as the bee and wasp, and the _diptera_, or insects with two
wings, as gnats, flies, gadflies, &c.; then come the spider tribe; some
_coleoptera_ (insects with crustaceous shells or elytra, which shut
together, and form a longitudinal suture down the back,) or beetles,
principally those which live on trees; such as the _elaterides_, or
leapers, and the _chrysomelida_. The lepidoptera, or insects with four
membranaceous wings, and pterigostea covered with mail-like scales, are
very rare in amber. We perceive from this enumeration, which results
from the labours of Germar, Schweiger, &c., that the insects enveloped
in this resinous matter are in general such as sit on the trunks of
trees, or live in the fissures of their bark. Hitherto, it has not been
found possible to refer them to any living species; but it has been
observed in general that they resemble more the insects of hot climates
than those of the temperate zones.

The districts where amber occurs in a condition fit for mining
operations are not numerous; but those in which it is met with in small
scattered bits are very abundant. Its principal exploitation is in
Eastern Prussia, on the coasts of the Baltic sea, from Memel to
Dantzick, particularly in the neighbourhood of Konigsberg, along the
shore which runs north and south from Grossdirschheim to Pillau, and in
several other places near Dantzick.

It is collected upon this coast in several ways; 1. In the beds of small
streams which run near the villages, and in rounded fragments without
bark, or in the sand-banks of rivers, in pieces thrown back by the sea,
and rounded by the waves. 2. If the pieces thrown up by the waters are
not numerous, the fishers, clothed in a leather dress, wade into the sea
up to the neck, seek to discover the amber by looking along its surface,
and seize it with bag nets, hung at the end of very long poles. They
conclude that a great deal of amber has been detached from the cliffs by
the sea, when many pieces of lignite (wood coal) are seen afloat. This
mode of collecting amber is not free from danger, and the fishers,
therefore, advance in troops, to lend each other aid in case of
accident; but their success, even thus, is most precarious. 3. The third
method of searching for amber is a real mining operation: it consists in
digging pits upon the borders of the sandy downs, sometimes to a depth
of more than 130 feet. 4. The last mode is by exploring the precipitous
sea cliffs in boats, and detaching masses of loose soil from them with
long poles terminating in iron hooks; a very hazardous employment. They
search the cliffs with great care at the level, where the amber nodules
commonly lie, and loosen the seams with their hooks; in which business
the boats are sometimes broken against the precipices, or sunk by an
avalanche of rubbish.

Amber occurs in Sicily, disseminated in beds of clay and marl, which lie
below the crag limestone. It is accompanied with bitumen; and, though a
scanty deposit, it is mined for sale. The pieces are coated with a kind
of whitish bark, present a variety of colours, and include many insects.
Amber is found in a great many places in the sandy districts of Poland,
at a very great distance from the sea, where it is mixed with cones of
the pine. In Saxony it is met with in the neighbourhood of Pretsch and
Wittemberg, in a bituminous clay mingled with lignite. At the embouchure
of the Jenissey, in Siberia, it occurs likewise along with lignite; as
also in Greenland.

Fine amber is considerably valued for making ornamental objects, and the
coarser kinds for certain uses in chemistry, medicine, and the arts. The
oriental nations prize more highly than the people of Europe trinkets
made of amber; and hence the chief commerce of the Pomeranian article is
with Turkey. The Prussian government is said to draw an annual revenue
of 17,000 dollars from amber. A good piece of a pound weight fetches 50
dollars. A mass weighing 13 pounds was picked up not long since in
Prussia, for which 5000 dollars were offered, and which would bring, in
the opinion of the Armenian merchants, from 30,000 to 40,000 dollars at
Constantinople. At one time it was customary to bake the opaque pieces
of amber in sand, at a gentle heat, for several hours, in order to make
it transparent, or to digest it in hot rapeseed oil, with the same view;
but how far these processes were advantageous does not appear.

When amber is to be worked into trinkets, it is first split on a leaden
plate at a lathe (see GEMS, _Cutting of_), and then smoothed into shape
on a Swedish whetstone. It is polished on the lathe with chalk and
water, or vegetable oil, and finished by friction with flannel. In these
processes the amber is apt to become highly electrical, very hot, and
even to fly into fragments. Hence, the artists work the pieces time
about, so as to keep each of them cool, and feebly excited. The men are
often seized with nervous tremors in their wrists and arms from the
electricity. Pieces of amber may be neatly joined by smearing their
edges with linseed oil, and pressing them strongly together, while they
are held over a charcoal fire. Solid specimens of amber, reported to
have been altogether fused by a particular application of heat, are now
shown in the royal cabinet of Dresden.

A strong and durable _varnish_ is made by dissolving amber in drying
linseed oil. For this purpose, however, the amber must be previously
heated in an iron pot, over a clear red fire, till it soften and be
semi-liquefied. The oil, previously heated, is to be now poured in, with
much stirring, in the proportion of 10 ounces to the pound of amber;
and after the incorporation is complete, and the liquid somewhat cooled,
a pound of oil of turpentine must be added. Some persons prescribe 2
ounces of melted shellac, though by this means they are apt to deepen
the colour, already rendered too dark by the roasting.

The fine black varnish of the coachmakers is said to be prepared by
melting 16 ounces of amber in an iron pot, adding to it half a pint of
drying linseed oil, boiling hot, of powdered resin and asphaltum 3
ounces each: when the materials are well united, by stirring over the
fire, they are to be removed, and, after cooling for some time, a pint
of warm oil of turpentine is to be introduced.

The _oil of amber_ enters into the composition of the old perfume called
_eau de luce_; and is convertible, by the action of a small quantity of
strong nitric acid, into a viscid mass like shoemakers’ rosin, which has
a strong odour of musk, and, under the name of artificial musk, has been
prescribed, in alcoholic solution, as a remedy against hooping cough,
and other spasmodic diseases.

Acid of amber (_succinic acid_) is a delicate reagent, in chemistry, for
separating red oxide of iron from compound metallic solutions.


AMBERGRIS. (_Ambregric_, Fr.; _Ambra_, Germ.).--A morbid secretion of
the liver of the spermaceti whale (physeter macrocephalus), found
usually swimming upon the sea. It occurs upon the coasts of Coromandel,
Japan, the Moluccas, and Madagascar, and has sometimes been extracted
from the rectum of whales in the South Sea fishery. It has a gray-white
colour, often with a black streak, or is marbled, yellow and black; has
a strong but rather agreeable smell, a fatty taste, is lighter than
water, melts at 60° C. (140° F.), dissolves readily in absolute alcohol,
in ether, and in both fat and volatile oils. It contains 85% of the
fragrant substance called _ambreine_. This is extracted from ambergris
by digestion with alcohol of 0·827, filtering the solution, and leaving
it to spontaneous evaporation. It is thus obtained in the form of
delicate white tufts: which are convertible into ambreic acid by the
action of nitric acid. Ambergris is used in perfumery.


AMIANTHUS. A mineral in silky filaments, called also ASBESTUS.


AMMONIA. A chemical compound, called also _volatile alkali_. This
substance, in its purest state, is a highly pungent gas, possessed of
all the mechanical properties of the air, but very condensable with
water. It consists of 3 volumes of hydrogen and 1 of azote condensed
into two volumes; and hence its density is 0·591, atmospheric air being
1·000. By strong compression and refrigeration it may be liquefied into
a fluid, whose specific gravity is 0·76 compared to water 1·000.

Ammonia gas is composed by weight of 82·53 azote and 17·47 hydrogen in
100 parts. It is obtained by mixing muriate of ammonia, commonly called
sal ammoniac, with quicklime, in a retort or still, applying a moderate
heat, and receiving the gas either over mercury for chemical
experiments, or in water to make liquid ammonia for the purposes of
medicine and the arts. Woulfe’s apparatus is commonly employed for this
condensation.

Ammonia is generated in a great many operations, and especially in the
decomposition of many organic substances, by fire or fermentation. Urine
left to itself for a few days is found to contain much carbonate of
ammonia, and hence this substance was at one time collected in great
quantities for the manufacture of certain salts of ammonia, and is still
used for its alkaline properties in making alum, scouring wool, &c. When
woollen rags, horns, bones, and other animal substances are decomposed
in close vessels by fire, they evolve a large quantity of ammonia, which
distils over in the form of a carbonate. The main source of ammonia now
in this country, for commercial purposes, is the coal gas works. A large
quantity of watery fluid is condensed in their tar pits, which contains,
chiefly ammonia combined with sulphuretted hydrogen and carbonic acid.
When this water is saturated with muriatic acid and evaporated it yields
muriate of ammonia, or sal ammoniac, somewhat impure, which is
afterwards purified by sublimation. See CARBONATE OF AMMONIA and SAL
AMMONIAC.

The soot of chimnies where coal is burned contains both sulphate and
carbonate of ammonia, and was extensively employed, at one time, to
manufacture these salts.

In making water of ammonia on the great scale, a cast iron still should
be preferred, and equal weights of quicklime and sal ammoniac should be
brought to the consistence of a pap, with water, before the heat is
applied. In this case, a refrigeratory worm or globe should be
interposed between the adopter tube of the capital of the still and the
bottles of Woulfe’s apparatus. The muriate of lime, or chloride of
calcium, which is left in the still when the whole ammonia is expelled,
is of no value. Water is capable of condensing easily about one third of
its weight of ammonia gas, or 460 times its bulk. The following table of
the quantity of ammonia in 100 parts by weight of its aqueous
combinations, at successive densities, is the result of very careful
experiments made by me, and recorded in the Philosophical Magazine for
March, 1821.

_Table of Water of Ammonia or Volatile Alkali, by Dr. Ure._

  +------+-------+------+-----------+--------+-------------------------+
  |Water |Ammonia|Water | Specific  |  Mean  |                         |
  | of   |  in   |  in  |gravity by |specific|   Equivalent primes.    |
  |0·900.| 100.  | 100. |experiment.|gravity.|                         |
  +------+-------+------+-----------+--------+-------------------------+
  | 100  |26·500 |73·500|   0·9000  |        |                         |
  |  95  |25·175 |74·825|   0·9045  |0·90452 |               _Wat. Am._|
  |  90  |23·850 |76·150|   0·9090  |0·90909 |    24 + 76,      6 to 1 |
  |  85  |22·525 |77·475|   0·9133  |0·91370 |                         |
  |  80  |21·200 |78·800|   0·9177  |0·91838 | 21·25 + 78·75,   7 to 1 |
  |  75  |19·875 |80·125|   0·9227  |0·92308 |                         |
  |  70  |18·550 |81·450|   0·9275  |0·92780 |  19·1 + 80·9,    8 to 1 |
  |  65  |17·225 |82·775|   0·9320  |0·93264 | 17·35 + 82·65,   9 to 1 |
  |  60  |15·900 |84·100|   0·9363  |0·93750 |  15·9 + 84·1,   10 to 1 |
  |  55  |14·575 |85·425|   0·9410  |0·94241 | 14·66 + 85·34,  11 to 1 |
  |  50  |13·250 |86·750|   0·9455  |0·94737 | 13·60 + 86·40,  12 to 1 |
  |  45  |11·925 |88·075|   0·9510  |0·95238 |  11·9 + 88·1,   14 to 1 |
  |  40  |10·600 |89·400|   0·9564  |0·95744 |  11·2 + 88·8,   15 to 1 |
  |  35  | 9·275 |90·725|   0·9614  |0·96256 |                         |
  |  30  | 7·950 |92·050|   0·9662  |0·96774 |  8·63 + 91·37,  20 to 1 |
  |  25  | 6·625 |93·375|   0·9716  |0·97297 |     7 + 93,     25 to 1 |
  |  20  | 5·300 |94·700|   0·9768  |0·97826 |     6 + 94,     30 to 1 |
  |  15  | 3·975 |96·025|   0·9828  |0·98360 |   4·5 + 95·5,   40 to 1 |
  |  10  | 2·650 |97·350|   0·9887  |0·98900 |     3 + 97,     60 to 1 |
  |   5  | 1·325 |98·675|   0·9945  |0·99447 |                         |
  +------+-------+------+-----------+--------+-------------------------+


AMMONIAC, gum-resin. This is the inspissated juice of an umbelliferous
plant (the _dorema armeniacum_) which grows in Persia. It comes to us
either in small white tears clustered together, or in brownish lumps,
containing many impurities. It possesses a peculiar smell, somewhat like
that of assafœtida, and a bitterish taste. It is employed in medicine.
Its only use in the arts is for forming a cement to join broken pieces
of china and glass, which may be prepared as follows: Take isinglass 1
ounce, distilled water 6 ounces, boil together down to 3 ounces, and add
1-1/2 ounce of strong spirit of wine;--boil this mixture for a minute or
two; strain it; add, while hot, first, half an ounce of a milky emulsion
of gum ammoniac, and then five drams of an alcoholic solution of resin
mastic. This resembles a substance sold in the London shops, under the
name of _diamond cement_. The recipe was given me by a respectable
dispensing chemist.


AMORPHOUS. _Without shape._ Said of mineral and other substances which
occur in forms not easy to be defined.


ANALYSIS. The art of resolving a compound substance or machine into its
constituent parts. Every manufacturer should so study this art, in the
proper treatises, and schools of Chemistry or Mechanics, as to enable
him properly to understand and regulate his business.

[Illustration: 6]


ANCHOR. (_Ancre_, Fr.; _Anker_, Germ.) An iron hook of considerable
weight and strength, for enabling a ship to lay hold of the ground, and
fix itself in a certain situation by means of a rope called the cable.
It is an instrument of the greatest importance to the navigator, since
upon its taking and keeping hold depends his safety upon many
occasions, especially near a lee shore, where he might be otherwise
stranded or shipwrecked. Anchors are generally made of wrought iron,
except among nations who cannot work this metal well, and who therefore
use copper. The mode in which an anchor operates will be understood from
inspection of _fig._ 6., where, from the direction of the strain, it is
obvious that the anchor cannot move without ploughing up the ground in
which its hook or fluke is sunk. When this, however, unluckily takes
place, from the nature of the ground, from the mode of insertion of the
anchor, or from the violence of the winds or currents, it is called
_dragging the anchor_. When the hold is good, the cable or the buried
arm will sooner break than the ship will drive. Anchors are of different
sizes, and have different names, according to the purposes they serve;
thus there are, _sheet_, _best bower_, _small bower_, _spare_, _stream_,
and _kedge anchors_. Ships of the first class have seven anchors, and
smaller vessels, such as brigs and schooners, three.

[Illustration: 7]

The manufacture of anchors requires great knowledge of the structure of
iron, and skill in the art of working it. I shall give, here, a brief
notice of the improved system introduced by Mr. Perring, clerk of the
cheque at Plymouth, in which the proportions of the parts are admirably
adapted to the strains they are likely to suffer. In _fig._ 7. A is the
_shank_; B, the _arm_ or _fluke_; C, the _palm_; D, the _blade_; E, the
_square_; F, the _nut_; G, the _ring_; H, the _crown_.

Formerly the shank was made of a number of square iron rods, laid
parallel together in a cylindrical form, and bound by iron hoops. When
they were welded into one bar, the exterior rods could not fail to be
partially burned and wasted by the strong heat. Mr. Perring abated this
evil by using bars of the whole breadth of the shank, and placing them
right over each other, hooping them and welding them together at two
heats into one solid mass. To any one who has seen the working of
puddled iron, with a heavy mill hammer, this operation will not appear
difficult.

He formed the crown with bars similarly distributed with those of the
shank. His mode of uniting the flukes to the crown is probably the most
valuable part of his invention. The bars and half the breadth of the
anchor are first welded separately, and then placed side by side, where
the upper half is worked into one mass, while the lower part is left
disunited, but has carrier iron bars, or _porters_, as these
prolongation rods are commonly called, welded to the extremity of each
portion. The lower part is now heated and placed in the clamping
machine, which is merely an iron plate firmly bolted to a mass of
timber, and bearing upon its surface four iron pins. One end of the
crown is placed between the first of these pins, and passed under an
iron strap; the other end is brought between the other pins, and is bent
by the leverage power of the elongated rods or porters.

Thus a part of the arm being formed out of the crown gives much greater
security that a true union of fibres is effected, than when the junction
was made merely by a short scarf.

The angular opening upon the side opposite B H, _fig._ 7., is filled
with the _chock_, formed of short iron bars placed upright. When this
has been firmly welded, the truss-piece is brought over it. This piece
is made of plates similar to the above, except that their edges are here
horizontal. The truss-piece is half the breadth of the arm; so that when
united to the crown, it constitutes, with the other parts, the total
breadth of the arms at those places.

The shank is now shut upon the crown; the square is formed, and the nuts
welded to it; the hole is punched out for the ring, and the shank is
then fashioned.

The blade is made much in the way above described. In making the palm,
an iron rod is first bent into the approximate form, notching it so that
it may more readily take the desired shape. To one end a _porter_ rod is
fastened, by which the palm is carried and turned round in the fire
during the progress of the fabrication. Iron plates are next laid side
by side upon the rod, and the joint at the middle is broken by another
plate laid over it. When the mass is worked, its under side is filled up
by similar plates, and the whole is completely welded; pieces being
added to the sides, if necessary, to form the angles of the palm. The
blade is then shut on to the palm, after which the part of the arm
attached to the blade is united to that which constitutes the crown. The
smith-work of the anchor is now finished.

The junction, or shutting on, as the workmen call it, of the several
members of an anchor, is effected by an instrument called a _monkey_,
which is merely a mass of iron raised to a certain height, between
parallel uprights, as in the pile engine or vertical ram, and let fall
upon the metal previously brought to a welding heat.

The _monkey_ and the _hercules_, both silly, trivial names, are similar
instruments, and are usually worked, like a portable pile engine, by the
hands of several labourers, pulling separate ropes. Many other modes of
manufacturing anchors have been devised, in which mechanical power is
more extensively resorted to.

The upper end of the shank F (_fig._ 7.) is squared to receive and hold
the stock steadily, and keep it from turning. To prevent it shifting
along, there are two knobs or tenon-like projections. The point of the
angle H, between the arms and the shank, is sometimes called the throat.
The arm B C generally makes an angle of 56° with the shank A; it is
either round or polygonal, and about half the length of the shank.

The _stock_ of the anchor (_fig._ 6.) is made of oak. It consists of two
beams which embrace the _square_, and are firmly united by iron bolts
and hoops, as shown in the figure. The stock is usually somewhat longer
than the shank, has in the middle a thickness about one-twelfth of its
length, but tapers at its under side to nearly one half this thickness
at the extremities. In small anchors the stock is frequently made of
iron; but in this case it does not embrace the anchor, but goes through
a hole made in the square, which is swelled out on purpose.

The weight of anchors for different vessels is proportioned to the
tonnage; a good rule being to make the anchor in hundredweights
one-twentieth of the number of tons of the burden. Thus a ship of 1000
tons would require a sheet anchor of 50 cwts. Ships of war are provided
with somewhat heavier anchors.

Several new forms and constructions of anchors were proposed under Mr.
Piper’s patent of November, 1822, by the adoption of which great
advantages as to strength were anticipated over every other form or
construction previously made.

The particular object was to preserve such a disposition of the fibres
of the metal as should afford the greatest possible strength; in doing
which the crossing or bending of the fibres at the junctions of the
shank, flukes, and crown, where great strength is required, has been
avoided as much as possible, so that the fibres are not disturbed or
injured.

In this respect most anchors are defective; for in connecting the shanks
to the crown-pieces, the grain of the metal is either crossed, or so
much curved, as to strain the fibre, and consequently induce a weakness
where the greatest strength is required. And, further, the very
considerable thicknesses of metal which are to be brought into immediate
contact by means of the hammer in forging anchors upon the old
construction, render it highly probable that faulty places may be left
within the mass, though they be externally imperceptible. Mr. Piper’s
leading principle was, that the fibre of the metal should run nearly
straight in all the parts where strength is particularly required.

[Illustration: 8]

_Fig._ 8. shows an anchor with one tumbling fluke, which passes through
the forked or branched part of the shank. The lower part of this anchor,
answering to the crown, has a spindle through it, upon which the fluke
turns, and a pin is there introduced for the purpose of confining the
fluke when in a holding position. This shank is formed of a solid piece
of wrought iron, the fibres of which run straight, and at the crown
holes are pierced, which merely bulge the metal without bending the
fibres round so as to strain them. The arm and fluke, also, are formed
of one piece punched through without curling or crossing the fibre, and
the spindle which holds the arm to the crown is likewise straight. This
spindle extends some distance on each side of the anchor, and is
intended to answer the purpose of a stock; for when either of the ends
of the spindle comes in contact with the ground, the anchor will be
thrown over into a holding position; or an iron stock may be introduced
near the shackle, instead of these projecting ends. In the descent of
the anchor, the fluke will fall over towards that side which is nearest
the ground, and will there be ready to take hold when the anchor is
drawn forward.

[Illustration: 9]

_Fig._ 9. is another anchor upon the same principle, but slightly varied
in form from the last. In this the forked part of the shank is closer
than in the former, and there are two arms or flukes connected to the
crown-pieces, one of which falls into its holding position as the anchor
comes to the ground, and is held at its proper angle by the other fluke
stopping against the shank.

[Illustration: 10]

_Fig._ 10. represents another variation in the form of these improved
anchors, having two tumbling flukes, which are both intended to take
hold of the ground at the same time. The shank is here, as before, made
without crossing the grain of the iron, and the eyes for admitting the
bolt at the crown and at the shackle are punched out of the solid, not
formed by welding or turning the iron round. In this form a guard is
introduced at the crown, to answer the purpose of a stock, by turning
the flukes over into a holding position. The arms and flukes are made,
as before described, of the straight fibre of the iron punched through,
and the flukes are fixed to the spindle, which passes through the
crown-piece.

[Illustration: 11]

_Fig._ 11. has a shank without any fork, but formed straight throughout;
the guard here is an elongated frame of iron, for the same purpose as a
stock, and is, with the tumbling flukes, fastened to the spindle, which
passes through the crown of the anchor, and causes the flukes to fall
into their holding position.

The principles of these new anchors are considered to consist in shanks
which are made of straight lengths of metal, and finished so that the
fibres of the iron shall not be injured by cross-shuts or uncertain
welding; also each arm and palm is made in one solid piece, and finished
in straight lines, so that the fibres will not be altered, and the
shaft-pin or spindle will also be in one straight line; and this is the
improvement claimed. These anchors being made in separate pieces, give a
great advantage to the workman to execute each part perfectly; for he
will not have such heavy weights to lift when hot, which will render
these anchors much stronger, with less weight; and if any accident
should happen to them, any part may be taken separate from the others to
be repaired, and several of those parts of the anchor which may be
likely to break may be carried on board, in case of accident. This
anchor is so contrived that one of thirty hundred weight may be taken to
pieces and put together again, by one man, in twenty minutes; it may
also be dismounted, and stowed in any part of the ship, in as little
room as straight bars of iron, and speedily put together again.

[Illustration: 12]

The anchor (_fig._ 12.) patented by Mr. Brunton, in February, 1822, has
its stock introduced at the crown part, for the purpose of turning it
over into a holding position. The shank is perforated through the solid,
in two places, with elliptical apertures, for the purpose of giving it a
greater stability, and more effectually resisting the strain to which
the anchor may be subjected. The stock is a cylindrical iron rod, held
at its extremities by lateral braces, which are bolted to the shank.

_Fig._ 12. shows the form of the anchor. The shank is seen upright, with
one of the flukes projecting in its front; the horizontal iron stock is
at bottom; and the oblique braces are bolted to both shank and stock.
The ends of the stock, from the shoulder, are formed dove-tailed, and
oval in the vertical direction, and are protruded through apertures in
the braces, also oval, but in the horizontal direction, and counter
sunk. When the ends of the stock have been thus introduced through the
holes, the braces are securely bolted to the shank; the ends of the
stock are then spread, by hammering into the counter-sunk holes of the
braces, and by that means they are made firm.

An anchor of this description is considered by the patentee to possess
considerable advantage, particularly in point of stability, over the
ordinary construction of anchors, and is economical, inasmuch as a less
weight of metal will give, upon this plan, an equal degree of strength.

An ingenious form of anchor was made the subject of a patent, by
Lieutenant Rodgers, of the Royal Navy, in 1828, and was afterwards
modified by him in a second patent, obtained in August, 1829. The whole
of the parts of the anchor are to be bound together by means of iron
bands or hoops, in place of bolts or pins.

[Illustration: 13 14 15 16]

_Fig._ 13. is a side view of a complete anchor, formed upon his last
improved construction, and _fig._ 14., a plan of the same; _fig._ 15.,
an end view of the crown and flukes, or arms; _fig._ 16. represents the
two principal iron plates, _a_, _a_, of which the shank is constructed,
but so as to form parts of the stump arms to which the flukes are to be
connected.

The crown piece is to be welded to the stump piece, _c c_, _fig._ 16.,
as well as to the end _l_ of the centre piece _h h_, and the scarfs _m
m_ are to be cut to receive the arms or flukes. Previously, however, to
uniting the arms or flukes with the stump arms, the crown and throat of
the anchor are to be strengthened, by the application of the crown slabs
_n n_, _fig._ 16., which are to be welded upon each side of the crown,
overlapping the end of the pillar _h_, and the throat or knees of the
stump arms and the crown piece. The stump arms are then to be
strengthened in a similar manner, by the thin flat pieces _p p_, which
are to be welded upon each side. The palms are united to the flukes in
the usual way, and the flukes are also united to the stump arms by means
of the long scarfs _m m_. When the shank of the anchor has been thus
formed, and united with the flukes, the anchor smith’s work may be said
to be complete.

[Illustration: 17]

Another of the improvements in the construction of anchors, claimed
under this patent, consists in a new method of affixing the stock upon
the shank of the anchor, which is effected in the following manner: in
_fig._ 14. the stock is shown affixed to the anchor; in _fig._ 17. it is
shown detached. It may be made either of one or two pieces of timber, as
may be found most convenient. It is, however, to be observed that the
stock is to be completed before fitting on to the shank. After the stock
is shaped, a hole is to be made through the middle of it, to fit that
part of the shank to which it is to be affixed. Two stock plates are
then to be let in, one on each side of the stock, and made fast by
counter sunk nails and straps, or hoops; other straps or hoops of iron
are also to be placed round the stock, as usual.

In place of nuts, formed upon the shank of the anchor, it is proposed to
secure the stock by means of a hoop and a key, shown above and below J,
in _fig._ 14. By this contrivance, the stock is prevented from going
nearer to the crown of the anchor than it ought to do, and the key
prevents it from sliding towards the shackle.

Since fitting the stock to the shank of an anchor, by this method,
prevents the use of a ring, as in the ordinary manner, the patentee says
that he in all cases substitutes a shackle for the ring, and which is
all that is required for a chain cable; but, when a hempen cable is to
be used, he connects a ring to the usual shackle, by means of a joining
shackle, as in _figs._ 13. and 14.

Mr. Rodgers proposes, under another patent, dated July, 1833, to alter
the size and form of the palms; having found from experience that
anchors with small palms will not only hold better than with large ones,
but that the arms of the anchor, even without any palms, have been found
to take more secure hold of the ground than anchors of the old
construction, of similar weight and length. He has, accordingly, fixed
upon one-fifth of the length of the arm, as a suitable proportion for
the length or depth of the palm. He makes the palms, also, broader than
they are long or deep.


ANIMÉ. A resin of a pale brown yellow colour, transparent and brittle.
It exudes from the courbaril of Cayenne, a tree which grows also in
various parts of South America. It occurs in pieces of various sizes,
and it often contains so many insects belonging to living species, as to
have merited its name, as being animated. It contains about a fifth of
one per cent. of a volatile oil, which gives it an agreeable odour.
Alcohol does not dissolve the genuine animé, as I have ascertained by
careful experiments; nor does caoutchoucine; but a mixture of the two,
in equal parts, softens it into a tremulous jelly, though it will not
produce a liquid solution. When reduced to this state, the insects can
be easily picked out, without injury to their most delicate parts.

The specific gravity of the different specimens of animé which I tried,
varied from 1·054 to 1·057. When exposed to heat, in a glass retort over
a spirit flame, it softens, and, by careful management, it may be
brought into liquid fusion, without discolouration. It then exhales a
few white vapours, of an ambrosiacal odour, which being condensed in
water, and the liquid being tested, is found to be succinic acid.
_Author._

It is extensively used by the varnish makers, who fuse it at a pretty
high heat, and in this state combine it with their oils, or other
varnishes.


ANKER. A liquid measure of Amsterdam, which contains 32 gallons English.


ANNEALING or NEALING. (_Le recuit_, Fr.; _das anlassen_, Germ.) A
process by which glass is rendered less frangible; and metals, which
have become brittle, either in consequence of fusion, or long-continued
hammering, are again rendered malleable. When a glass vessel is allowed
to cool immediately after being made, it will often sustain the shock of
a pistol-bullet, or any other blunt body falling into it from a
considerable height; while a small splinter of flint, or an angular
fragment of quartz, dropped gently into it, makes it sometimes
immediately, sometimes after a few minutes, fly to pieces with great
violence. This extreme fragility is prevented by annealing, or placing
the vessels in an oven, where they take several hours or even some days
to cool. Similar phenomena are exhibited in a higher degree by
glass-tears, or Prince Rupert’s drops. They are procured by letting
drops of melted glass fall into cold water. Their form resembles that of
a pear, rounded at one extremity, and tapering to a very slender tail at
the other. If a part of the tail be broken off, the whole drop flies to
pieces with a loud explosion; and yet the tail of a drop may be cut away
by a glass-cutter’s wheel, or the thick end may be struck smartly with
a hammer, without the fear of sustaining any injury. When heated to
redness, and permitted to cool gradually in the open air, they lose
these peculiarities, and do not differ sensibly from common glass.

The properties of unannealed glass depend on a peculiar structure,
extending uniformly through its whole substance; and the bursting of a
glass drop by breaking off the tail, or of an unannealed glass vessel,
by dropping a piece of flint into it, arises from a crack being thus
begun, which afterwards extends its ramifications in different
directions throughout the glass.

When metals have been extended to a certain degree under the hammer,
they become brittle, and incapable of being further extended without
cracking. In this case the workman restores their malleability by
annealing, or heating them red-hot. The rationale of this process seems
to be, that the hammering and extension of the metal destroy the kind of
arrangement which the particles of the metal had previous to the
hammering; and that the annealing, by softening the metal, enables it to
recover its original structure.

Of late years a mode has been discovered of rendering cast iron
malleable, without subjecting it to the action of puddling. The process
is somewhat similar to that employed in annealing glass. The metal is
kept for several hours at a temperature a little below its fusing point,
and then allowed to cool slowly. In this manner vessels are made of cast
iron which can sustain considerable violence, without being broken. See
STEEL, softening of.


ANNOTTO. (_Rocou_, or _roucou_, Fr.; _orleans_, Germ.) A somewhat dry
and hard paste, brown without, and red within. It is usually imported in
cakes of two or three pounds weight, wrapped up in leaves of large
reeds, packed in casks, from America, where it is prepared from the
seeds of a certain tree, the _bixa orellana_, of Linnæus.

The pods of the tree being gathered, their seeds are taken out and
bruised; they are then transferred to a vat, which is called the
steeper, where they are mixed with as much water as covers them. Here
the substance is left for several weeks, or even months; it is now
squeezed through sieves placed above the steeper, that the water
containing the colouring matter in suspension may return, into the vat.
The residuum is preserved under the leaves of the anana (pine-apple)
tree, till it becomes hot by fermentation. It is again subjected to the
same operation, and this treatment is continued till no more colour
remains.

The substance thus extracted is passed through sieves, in order to
separate the remainder of the seeds, and the colour is allowed to
subside. The precipitate is boiled in coppers till it be reduced to a
consistent paste; it is then suffered to cool, and dried in the shade.

Instead of this long and painful labour, which occasions diseases by the
putrefaction induced, and which affords a spoiled product, Leblond
proposes simply to wash the seeds of annotto till they be entirely
deprived of their colour, which lies wholly on their surface; to
precipitate the colour by means of vinegar or lemon juice, and to boil
it up in the ordinary manner, or to drain it in bags, as is practised
with indigo.

The experiments which Vauquelin made on the seeds of annotto imported by
Leblond, confirmed the efficacy of the process which he proposed; and
the dyers ascertained that the annotto obtained in this manner was worth
at least four times more than that of commerce; that, moreover, it was
more easily employed; that it required less solvent; that it gave less
trouble in the copper, and furnished a purer colour.

Annotto dissolves better and more readily in alcohol than in water, when
it is introduced into the yellow varnishes for communicating an orange
tint.

The decoction of annotto in water has a strong peculiar odour, and a
disagreeable taste. Its colour is yellowish-red, and it remains a little
turbid. An alkaline solution renders its orange-yellow clearer and more
agreeable, while a small quantity of a whitish substance is separated
from it, which remains suspended in the liquid. If annotto be boiled in
water along with an alkali, it dissolves much better than when alone,
and the liquid has an orange hue.

The acids form with this liquor an orange-coloured precipitate, soluble
in alkalies, which communicate to it a deep orange colour. The
supernatant liquor retains only a pale yellow hue.

When annotto is used as a dye, it is always mixed with alkali, which
facilitates its solution, and gives it a colour inclining less to red.
The annotto is cut in pieces, and boiled for some instants in a copper
with its own weight of crude pearl ashes, provided the shade wanted do
not require less alkali. The cloths may be thereafter dyed in this bath,
either by these ingredients alone, or by adding others to modify the
colour; but annotto is seldom used for woollen, because the colours
which it gives are too fugitive, and may be obtained by more permanent
dyes. Hellot employed it to dye a stuff, prepared with alum and tartar;
but the colour acquired had little permanence. It is almost solely used
for silks.

For silks intended to become aurora and orange, it is sufficient to
scour them at the rate of 20 per cent. of soap. When they have been well
cleansed, they are immersed in a bath prepared with water, to which is
added a quantity of alkaline solution of annotto, more or less
considerable according to the shade that may be wanted. This bath should
have a mean temperature, between that of tepid and boiling water.

When the silk has become uniform, one of the hanks is taken out, washed,
and wrung, to see if the colour be sufficiently full; if it be not so,
more solution of annotto is added, and the silk is turned again round
the sticks: the solution keeps without alteration.

When the desired shade is obtained, nothing remains but to wash the
silk, and give it two beetlings at the river, in order to free it from
the redundant annotto, which would injure the lustre of the colour.

When raw silks are to be dyed, those naturally white are chosen, and
dyed in the annotto bath, which should not be more than tepid, or even
cold, in order that the alkali may not attack the gum of the silk, and
deprive it of the elasticity which it is desirable for it to preserve.

What has been now said regards the silks to which the aurora shades are
to be given; but to make an orange hue, which contains more red than the
aurora, it is requisite, after dyeing with annotto, to redden the silks
with vinegar, alum, or lemon juice. The acid, by saturating the alkali
employed for dissolving the annotto, destroys the shade of yellow that
the alkali had given, and restores it to its natural colour, which
inclines a good deal to red.

For the deep shades, the practice at Paris, as Macquer informs us, is to
pass the silks through alum; and if the colour be not red enough, they
are passed through a faint bath of brazil wood. At Lyons, the dyers who
use carthamus, sometimes employ old baths of this ingredient for dipping
the deep oranges.

When the orange hues have been reddened by alum, they must be washed at
the river; but it is not necessary to beetle them, unless the colour
turns out too red.

Shades may be obtained also by a single operation, which retain a
reddish tint, employing for the annotto bath a less proportion of alkali
than has been pointed out.

Guhliche recommends to avoid heat in the preparation of annotto. He
directs it to be placed in a glass vessel, or in a glazed earthen one;
to cover it with a solution of pure alkali; to leave the mixture at rest
for 24 hours; to decant the liquor, filter it, and add water repeatedly
to the residuum, leaving the mixture each time at rest for two or three
days, till the water is no longer coloured; to mix all these liquors,
and preserve the whole for use in a well-stopped vessel.

He macerates the silk for 12 hours in a solution of alum, at the rate of
an eighth of this salt for one part of silk, or in a water rendered
acidulous by the aceto-citric acid above described; and he wrings it
well on its coming out of this bath.

Silk thus prepared is put into the annotto bath quite cold. It is kept
in agitation there till it has taken the shade sought for; or the liquor
may be maintained at a heat far below ebullition. On being taken out of
the bath, the silk is to be washed and dried in the shade.

For lighter hues, a liquor less charged with colour is taken; and a
little of the acid liquid which has served for the mordant may be added,
or the dyed silk may be passed through the acidulous water.

We have seen the following preparation employed for cotton velvet:--one
part of quicklime, one of potash, two of soda.

Of these a ley is formed, in which one part of annotto is dissolved; and
the mixture is boiled for an hour and a half. This bath affords the
liveliest and most brilliant auroras. The buff (chamois) fugitive dye is
also obtained with this solution. For this purpose only a little is
wanted; but we must never forget, that the colours arising from annotto
are all fugitive.

Dr. John found in the pulp surrounding the unfermented fresh seeds,
which are about the size of little peas, 28 parts of colouring resinous
matter, 26·5 of vegetable gluten, 20 of ligneous fibre, 20 of colouring
extractive matter, 4 formed of matters analogous to vegetable gluten and
extractive, and a trace of spicy and acid matters.

The Gloucestershire cheese is coloured with annotto, in the proportion
of one cwt. to an ounce of the dye.

When used in calico-printing, it is usually mixed with potash or ammonia
and starch.

It is an appropriate substance for tingeing varnishes, oils, spirits,
&c.

The import duty upon annotto is 1_s._ per cwt. for flag, and 4_s._ for
other sorts. In 1834, 252,981 lbs. were imported; and in 1835, 163,421
lbs. The revenue from this drug in these two years, was 180_l._ and
98_l._ respectively.


ANTHRACITE, from ανθραξ, coal, is a species of coal found in the
transition rock formation, and is often called stone coal. It has a
grayish black, or iron black colour, an imperfectly metallic lustre,
conchoidal fracture, and a specific gravity of from 1·4 to 1·6, being,
therefore, much denser than the coal of the proper coal measures. It
consists wholly of carbon, with a small and variable proportion of
iron, silica, and alumina. It is difficult to kindle in separate masses,
and burns when in heaps or grates without smell or smoke, leaving
sometimes an earthy residuum. It has been little explored or worked in
the old world; but is extensively used in the United States of America,
and has become of late years a most valuable mineral to that country,
where it is burned in peculiar grates, adapted to its difficult
combustion. In Pennsylvania the anthracite coal formation has been
traced through a tract many miles in width, and extending across the two
entire counties of Luzerne and Schuylkill. At Maunch Chunk, upon the
Lehigh, 800 men were employed so far back as 1825, in digging this coal.
In that year 750,000 bushels were dispatched for Philadelphia. It is
worked there with little cost or labour, being situated on hills from
300 to 600 feet above the level of the neighbouring rivers and canals,
and existing in nearly horizontal beds, of from 15 to 40 feet in
thickness, covered by only a few feet of gravelly loam. At Portsmouth,
in Rhode Island, an extensive stratum of this coal has been worked, with
some interruptions, for 20 years; and more recently a mine of anthracite
has been opened at Worcester, in Massachusetts, at the head of the
Blackstone canal. It has been of late employed in South Wales, for
smelting iron, and in a cupola blast furnace, by Mr. Crane.


ANTIGUGGLER. A small syphon of metal, which is inserted into the mouths
of casks, or large bottles, called carboys, to admit air over the liquor
contained in them, and thus to facilitate their being emptied without
agitation or a guggling noise.


ANTIMONY. (_Antimoine_, Fr.; _Spiessglanz_, or _Spiessglass_, Ger.) The
only ore of this metal found in sufficient abundance to be smelted, is
the sulphuret, formerly called crude antimony. It occurs generally in
masses, consisting of needles closely aggregated, of a metallic lustre,
a lead-gray colour, inclining to steel-gray, which is unchanged in the
streak. The needles are extremely brittle, and melt even in the flame of
a candle, with the exhalation of a sulphureous smell. The powder of this
sulphuret is very black, and was employed by women in ancient times to
stain their eyebrows and eyelids. This ore consists in 100 parts of
72·86 metal, and 27·14 sulphur. Specific gravity from 4·13 to 4·6.

The veins of sulphuret of antimony occur associated with gangues of
quartz, sulphate of barytes, and carbonate of lime; those of Allémont
occur in the numerous fissures of a mica schist, evidently primitive.

In treating the ore to obtain the metal, the first object is to separate
the gangue, which was formerly done by filling crucibles with the mixed
materials, placing them on the hearth of an oven, and exposing them to a
moderate heat. As the sulphuret easily melts, it ran out through a hole
in the bottom of the crucible into a pot placed beneath, and out of the
reach of the fire. But the great loss from breakage of the crucibles,
has caused another method to be adopted. In this the broken ore, being
sorted, is laid on the bottom of a concave reverberatory hearth, where
it is reduced.

[Illustration: 18 19]

_Figs._ 18. 19. represent a wind or flame furnace, for the reduction of
antimony. The hearth is formed of sand and clay solidly beat together,
and slopes from all sides towards the middle, where it is connected with
the orifice _a_, which is closed with dense coal-ashes; _b_ is the air
channel up through the bridge; _c_, the door for introducing the
prepared ore, and running off the slags; _d_, the bridge; _e_, the
grate; _f_, the fire or fuel-door; _g_, the chimney. With 2 or 3 cwt. of
ore, the smelting process is completed in from 8 to 10 hours. The metal
thus obtained is not pure enough, but must be fused under coal dust, in
portions of 20 or 30 pounds, in crucibles, placed upon a reverberatory
hearth.

To obtain antimony free from iron, it should be fused with some
antimonic oxide in a crucible, whereby the iron is oxidized and
separated. The presence of arsenic in antimony is detected by the garlic
smell, emitted by such an alloy when heated at the blow-pipe; or,
better, by igniting it with nitre in a crucible; in which case,
insoluble antimonite and antimoniate of potash will be formed along with
soluble arseniate. Water digested upon the mixture, filtered, and then
tested with nitrate of silver, will afford the brown-red precipitate
characteristic of arsenic acid.

According to Berthier, the following materials afford, in smelting, an
excellent product of antimony: 100 parts of sulphuret; 60 of
hammerschlag (protoxide of iron from the shingling or rolling mills); 45
to 50 of carbonate of soda; and 10 of charcoal powder. From 65 to 70
parts of metallic antimony or regulus should be obtained. Glauber salts
may be used instead of soda. For another mode of smelting antimony, at
Malbosc, in the department of Ardèche, in France, see LIQUATION.

In the works where antimonial ores are smelted, by means of tartar
(argol), the alkaline scoriæ, which cover the metallic ingots, are not
rejected as useless, for they hold a certain quantity of antimonial
oxide in combination; a property of the potash flux, which is propitious
to the purity of the metal. These scoriæ, consisting of sulphuret of
potassium and antimonite of potash, being treated with water, undergo a
reciprocal decomposition; the elements of the water act on those of the
sulphuret, and the resulting alkaline hydro-sulphuret re-acts on the
antimonial solution, so as to form a species of _kermes mineral_, which
precipitates. This is dried, and sold at a low price as a veterinary
medicine, under the name of _kermes_, by the dry way.

Metallic antimony, as obtained by the preceding process, is the antimony
of commerce, but is not absolutely pure; containing frequently minute
portions of iron, lead, and even arsenic; the detection and separation
of which belong to the sciences of chemistry and pharmacy. Antimony is a
brittle metal, of a silvery white colour, with a tinge of blue, a
lamellar texture, and crystalline fracture. When heated at the blowpipe,
it melts with great readiness, and diffuses white vapours, possessing
somewhat of a garlic smell. If thrown in this melted state on a sheet of
flat paper, the globule sparkles, and bursts into a multitude of small
spheroids, which retain their incandescence for a long time, and run
about on the paper, leaving traces of the white oxide produced during
the combustion. When this oxide is fused with borax, or other vitrifying
matter, it imparts a yellow colour to it. Metallic antimony, treated
with hot nitric acid and in a concentrated state, is converted into a
powder, called antimonious acid, which is altogether insoluble in the
ordinary acid menstrua; a property by which the chemist can separate
that metal from lead, iron, copper, bismuth, and silver. According to
Bergman, the specific gravity of antimony is 6·86; but Haidinger makes
the Swedish native metal only 6·646. The alchemists had conceived the
most brilliant hopes of this metal; the facility with which it is
alloyed with gold, since its fumes alone render this most ductile metal
immediately brittle, led them to assign to it a royal lineage, and to
distinguish it by the title of _regulus_, or the little king.

Its chief employment now is in medicine, and in making the alloys called
type metal, stereotype metal, music plates, and Britannia-metal; the
first consisting of 6 of lead and 2 of antimony; the second of 6 of lead
and 1 of antimony; the third of lead, tin, and antimony; and the fourth
also of lead, tin, and antimony, with occasionally a little copper and
bismuth.--For Glass of antimony, see PASTES.


ANTISEPTICS. Substances which counteract the spontaneous decomposition
of animal and vegetable substances. These are chiefly culinary salt,
nitre, spices, and sugar, which operate partly by inducing a change in
the animal or vegetable fibres, and partly by rendering the aqueous
constituent unsusceptible of decomposition. See PROVISIONS, CURING OF.


ANVIL. A mass of iron, having a smooth and nearly flat top surface of
steel; upon which blacksmiths, and various other artificers, forge
metals with the hammer. The common anvil is usually made of seven
pieces: 1, the core, or body; 2, 3, 4, 5, the four corner pieces which
serve to enlarge its base; 6, the projecting end, which has a square
hole for the reception of the tail or shank of a chisel on which iron
bars may be cut through; and 7, the beak, or horizontal cone round which
rods or slips of metal may be turned into a circular form, as in making
rings. These 6 pieces are welded separately to the first, or core, and
then hammered into an uniform body. In manufacturing large anvils two
hearths are needed, in order to bring each of the two pieces to be
welded, to a proper heat by itself; and several men are employed in
working them together briskly in the welding state, by heavy swing
hammers. The steel facing is applied by welding in the same manner. The
anvil is then hardened by heating it to a cherry red, and plunging it
into cold water; a running stream being preferable to a pool or cistern.
The facing should not be too thick a plate, for, when such, it is apt to
crack in the hardening. The face of the anvil is now smoothed upon a
grindstone, and finally polished with emery and crocus, for all delicate
purposes of art.

The blacksmith, in general, sets his anvil loosely upon a wooden block,
and in preference on the root of an oak. But the cutlers and file-makers
fasten their anvils to a large block of stone; which is an advantage,
for the more firmly and solidly this tool is connected to the earth, the
more efficacious will be the blows of the hammer on any object placed
upon it.


AQUAFORTIS. Nitric acid, somewhat dilute, was so named by the alchemists
on account of its strong solvent and corrosive operation upon many
mineral, vegetable, and animal substances. See NITRIC ACID.


AQUA REGIA. The name given by the alchemists to that mixture of nitric
and muriatic acids which was best fitted to dissolve gold, styled by
them the king of the metals. It is now called _nitro-muriatic acid_.


AQUA VITÆ. The name very absurdly given to alcohol, when used as an
intoxicating beverage. It has been the _aqua mortis_ to myriads of the
human race; and will, probably, ere long destroy all the native tribes
of North America and Australia.


ARCHIL. A violet red paste used in dyeing, of which the substance called
_cudbear_ in Scotland (from _Cuthbert_, its first preparer in that
form), is a modification. Two kinds of archil are distinguished in
commerce, the _archil_ plant of the Canaries, and that of Auvergne. The
first is most esteemed: it is prepared from the _lichen rocellus_, which
grows on rocks adjoining the sea in the Canary and Cape de Verde
Islands, in Sardinia, Minorca, &c., as well as on the rocks of Sweden.
The second species is prepared from the _lichen parellus_, which grows
on the basaltic rocks of Auvergne.

There are several other species of lichen which might be employed in
producing an analogous dye, were they prepared, like the preceding, into
the substance called _archil_. Hellot gives the following method for
discovering if they possess this property. A little of the plant is to
be put into a glass vessel; it is to be moistened with ammonia and
lime-water in equal parts; a little muriate of ammonia (sal ammoniac) is
added; and the small vessel is corked. If the plant be of a nature to
afford a red dye, after three or four days, the small portion of liquid,
which will run off on inclining the vessel, now opened, will be tinged
of a crimson red, and the plant itself will have assumed this colour. If
the liquor or the plant does not take this colour, nothing need be hoped
for; and it is useless to attempt its preparation on the great scale.
Lewis says, however, that he has tested in this way a great many mosses,
and that most of them afforded him a yellow or reddish brown colour; but
that he obtained from only a small number a liquor of a deep red, which
communicated to cloth merely a yellowish-red colour.

Prepared archil gives out its colour very readily to water, ammonia, and
alcohol. Its solution in alcohol is used for filling spirit-of-wine
thermometers; and when these thermometers are well freed from air, the
liquor loses its colour in some years, as Abbé Nollet observed. The
contact of air restores the colour, which is destroyed anew, in vacuo,
in process of time. The watery infusion loses its colour, by the
privation of air, in a few days; a singular phenomenon, which merits new
researches.

The infusion of archil is of a crimson bordering on violet. As it
contains ammonia, which has already modified its natural colour, the
fixed alkalies can produce little change on it, only deepening the
colour a little, and making it more violet. Alum forms in it a
precipitate of a brown red; and the supernatant liquid retains a
yellowish-red colour. The solution of tin affords a reddish precipitate,
which falls down slowly; the supernatant liquid retains a feeble red
colour. The other metallic salts produce precipitates which offer
nothing remarkable.

The watery solution of archil applied to cold marble, penetrates it,
communicating a beautiful violet colour, or a blue bordering on purple,
which resists the air much longer than the archil colours applied to
other substances. Dufay says, that he has seen marble tinged with this
colour preserve it without alteration at the end of two years.

To dye with archil, the quantity of this substance deemed necessary,
according to the quantity of wool or stuff to be dyed, and according to
the shade to which they are to be brought, is to be diffused in a bath
of water as soon as it begins to grow warm. The bath is then heated till
it be ready to boil, and the wool or stuff is passed through it without
any other preparation, except keeping that longest in, which is to have
the deepest shade. A fine gridelin, bordering upon violet, is thereby
obtained; but this colour has no permanence. Hence archil is rarely
employed with any other view than to modify, heighten, and give lustre
to the other colours. Hellot says, that having employed archil on wool
boiled with tartar and alum, the colour resisted the air no more than
what had received no preparation. But he obtained from herb archil
(_l’orseille d’herbe_) a much more durable colour, by putting in the
bath some solution of tin. The archil thereby loses its natural colour,
and assumes one approaching more or less to scarlet, according to the
quantity of solution of tin employed. This process must be executed in
nearly the same manner as that of scarlet, except that the dyeing may be
performed in a single bath.

Archil is frequently had recourse to for varying the different shades
and giving them lustre; hence it is used for violets, lilacs, mallows,
and rosemary flowers. To obtain a deeper tone, as for the deep _soupes
au vin_, sometimes a little alkali or milk of lime is mixed with it. The
suites of this browning may also afford agates, rosemary flowers, and
other delicate colours, which cannot be obtained so beautiful by other
processes. Alum cannot be substituted for this purpose; it not only does
not give this lustre, but it degrades the deep colours.

The herb-archil is preferable to the archil of Auvergne, from the
greater bloom which it communicates to the colours, and from the larger
quantity of colouring matter. It has, besides, the advantage of bearing
ebullition. The latter, moreover, does not answer with alum, which
destroys the colour; but the herb archil has the inconvenience of dyeing
in an irregular manner, unless attention be given to pass the cloth
through hot water as soon as it comes out of the dye.

Archil alone is not used for dyeing silk, unless for lilacs; but silk is
frequently passed through a bath of archil, either before dyeing it in
other baths or after it has been dyed, in order to modify different
colours, or to give them lustre. Examples of this will be given in
treating of the compound colours. It is sufficient here to point out how
white silks are passed through the archil bath. The same process is
performed with a bath more or less charged with this colour, for silks
already dyed.

Archil, in a quantity proportioned to the colour desired, is to be
boiled in a copper. The clear liquid is to be run off quite hot from the
archil bath, leaving the sediment at the bottom, into a tub of proper
size, in which the silks, newly scoured with soap, are to be turned
round on the skein-sticks with much exactness, till they have attained
the wished-for shade. After this they must receive one beetling at the
river.

Archil is in general a very useful ingredient in dyeing; but as it is
rich in colour, and communicates an alluring bloom, dyers are often
tempted to abuse it, and to exceed the proportions that can add to the
beauty without at the same time injuring in a dangerous manner the
permanence of the colours. Nevertheless, the colour obtained when
solution of tin is employed, is less fugitive than without this
addition: it is red, approaching to scarlet. Tin appears to be the only
ingredient which can increase its durability. The solution of tin may be
employed, not only in the dyeing bath, but for the preparation of the
silk. In this case, by mixing the archil with other colouring
substances, dyes may be obtained which have lustre with sufficient
durability.

We have spoken of the colour of the archil as if it were natural to it;
but it is, really, due to an alkaline combination. The acids make it
pass to red, either by saturating the alkali, or by substituting
themselves for the alkali.

The lichen which produces archil is subjected to another preparation, to
make turnsole (litmus). This article is made in Holland. The lichen
comes from the Canary Islands, and also from Sweden. It is reduced to a
fine powder by means of a mill, and a certain proportion of potash is
mixed with it. The mixture is watered with urine, and allowed to suffer
a species of fermentation. When this has arrived at a certain degree,
carbonate of lime in powder is added, to give consistence and weight to
the paste, which is afterwards reduced into small parallelopipeds that
are carefully dried.

The latest researches on the lichens, as objects of manufacture, are
those of Westring of Stockholm. He examined 150 species, among which he
found several which might be rendered useful. He recommends that the
colouring matter should be extracted in the places where they grow,
which would save a vast expense in curing, package, carriage, and waste.
He styles the colouring substance itself cutbear, persio, or turnsole;
and distributes the lichens as follows:--1st. Those which left to
themselves, exposed to moderate heat and moisture, may be fixed without
a mordant upon wool or silk; such are the L. _cinereus_, _æmatonta_,
_ventosus_, _corallinus_, _westringii_, _saxatilis_, _conspassus_,
_barbatus_, _plicatus_, _vulpinus_, &c.

2. Those which develop a colouring matter fixable likewise without
mordant, but which require boiling and a complicated preparation; such
are the lichens _subcarneus_, _dillenii_, _farinaceus_, _jubatus_,
_furfuraceus_, _pulmonareus_, _cornigatus_, _cocciferus_, _digitatus_,
_ancialis_, _aduncus_, &c. Saltpetre or sea-salt are requisite to
improve the lustre and fastness of the dye given by this group to silk.

3. Those which require a peculiar process to develop their colour; such
as those which become purple through the agency of stale urine or
ammonia. Westring employed the following mode of testing:--He put three
or four drachms of the dried and powdered lichen into a flask; moistened
it with three or four measures of cold spring water; put the stuff to be
dyed into the mixture, and left the flask in a cool place. Sometimes he
added a little salt, saltpetre, quicklime, or sulphate of copper. If no
colour appeared, he then moistened the lichen with water containing one
twentieth of sal ammoniac, and one tenth of quicklime, and set the
mixture aside in a cool place from eight to fourteen days. There
appeared in most cases a reddish or violet coloured tint. Thus the
_lichen cinereus_ dyed silk a deep carmelite, and wool a light
carmelite; the _l. physodes_ gave a yellowish-gray; the _pustulatus_, a
rose red; _sanguinarius_, gray; _tartareus_, found on the rocks of
Norway, Scotland, and England, dyes a crimson-red. In Jutland, cutbear
is made from it, by grinding the dry lichen, sifting it, then setting it
to ferment in a close vessel with ammonia. The lichen must be of the
third year’s growth to yield an abundant dye; and that which grows near
the sea is the best. It loses half its weight by drying. A single person
may gather from twenty to thirty pounds a day in situations where it
abounds. No less than 2,239,685 pounds were manufactured at
Christiansand, Flekkefiort, and Fakrsund, in Norway, in the course of
the six years prior to 1812. Since more solid dyes of the same shade
have been invented, the archil has gone much into disuse. Federigo, of
Florence, who revived its use at the beginning of the fourteenth
century, made such an immense fortune by its preparation, that his
family became one of the grandees of that city, under the name of
Oricellarii, or Rucellarii. For more than a century Italy possessed the
exclusive art of making archil, obtaining the lichens from the islands
of the Mediterranean. According to an official report of 1831, Teneriffe
furnished annually 500 quintals (cwts.) of lichen; the Canary Isles,
400; Fuerta Santura, 300; Lancerot, 300; Gomera, 300; isle of Ferro,
800. This business belonged to the crown, and brought it a revenue of
1500 piastres. The farmers paid from 15 to 20 reals for the right to
gather each quintal. At that time the quintal fetched in the London
market 4_l._ sterling.

Archil is perhaps too much used in some cloth factories of England, to
the discredit of our dyes. It is said, that by its aid one third of the
indigo may be saved in the blue vat; but the colour is so much the more
perishable. The fine soft tint induced upon much of the black cloth by
means of archil is also deceptive. One half-pound of cutbear will dye
one pound of woollen cloth. A crimson red is obtained by adding to the
decoction of archil a little salt of tin (muriate), and passing the
cloth through the bath, after it has been prepared by a mordant of tin
and tartar. It must be afterwards passed through hot water.


ARDENT SPIRIT. Alcohol of moderate strength.


AREOMETER OF BAUMÉ. This scale is much used by the French authors.

Specific Gravity Numbers corresponding with Baumé’s Areometric Degrees.

  +-----------------------------------------+---------------------------+
  |      Liquids denser than Water.         |  Less dense than Water.   |
  +------+------+------+------+------+------+------+------+------+------+
  |      | Spe- |      | Spe- |      | Spe- |      | Spe- |      | Spe- |
  | De-  |cific | De-  |cific | De-  |cific | De-  |cific | De-  |cific |
  |grees.|gravi-|grees.|gravi-|grees.|gravi-|grees.|gravi-|grees.|gravi-|
  |      | ty.  |      | ty.  |      | ty.  |      | ty.  |      | ty.  |
  +------+------+------+------+------+------+------+------+------+------+
  |   0  |1·0000|  26  |1·2063|  52  |1·5200|  10  |1·0000|  36  |0·8488|
  |   1  |1·0066|  27  |1·2160|  53  |1·5353|  11  |0·9932|  37  |0·8439|
  |   2  |1·0133|  28  |1·2258|  54  |1·5510|  12  |0·9865|  38  |0·8391|
  |   3  |1·0201|  29  |1·2358|  55  |1·5671|  13  |0·9799|  39  |0·8313|
  |   4  |1·0270|  30  |1·2459|  56  |1·5833|  14  |0·9733|  40  |0·8295|
  |   5  |1·0340|  31  |1·2562|  57  |1·6000|  15  |0·9669|  41  |0·8249|
  +------+------+------+------+------+------+------+------+------+------+
  |   6  |1·0411|  32  |1·2667|  58  |1·6170|  16  |0·9605|  42  |0·8202|
  |   7  |1·0483|  33  |1·2773|  59  |1·6344|  17  |0·9542|  43  |0·8156|
  |   8  |1·0556|  34  |1·2881|  60  |1·6522|  18  |0·9480|  44  |0·8111|
  |   9  |1·0630|  35  |1·2992|  61  |1·6705|  19  |0·9420|  45  |0·8066|
  |  10  |1·0704|  36  |1·3103|  62  |1·6889|  20  |0·9359|  46  |0·8022|
  +------+------+------+------+------+------+------+------+------+------+
  |  11  |1·0780|  37  |1·3217|  63  |1·7079|  21  |0·9300|  47  |0·7978|
  |  12  |1·0857|  38  |1·3333|  64  |1·7273|  22  |0·9241|  48  |0·7935|
  |  13  |1·0935|  39  |1·3451|  65  |1·7471|  23  |0·9183|  49  |0·7892|
  |  14  |1·1014|  40  |1·3571|  66  |1·7674|  24  |0·9125|  50  |0·7849|
  |  15  |1·1095|  41  |1·3694|  67  |1·7882|  25  |0·9068|  51  |0·7807|
  +------+------+------+------+------+------+------+------+------+------+
  |  16  |1·1176|  42  |1·3818|  68  |1·8095|  26  |0·9012|  52  |0·7766|
  |  17  |1·1259|  43  |1·3945|  69  |1·8313|  27  |0·8957|  53  |0·7725|
  |  18  |1·1343|  44  |1·4074|  70  |1·8537|  28  |0·8902|  54  |0·7684|
  |  19  |1·1428|  45  |1·4206|  71  |1·8765|  29  |0·8848|  55  |0·7643|
  |  20  |1·1515|  46  |1·4339|  72  |1·9000|  30  |0·8795|  56  |0·7604|
  +------+------+------+------+------+------+------+------+------+------+
  |  21  |1·1603|  47  |1·4476|  73  |1·9241|  31  |0·8742|  57  |0·7656|
  |  22  |1·1692|  48  |1·4615|  74  |1·9487|  32  |0·8690|  58  |0·7526|
  |  23  |1·1783|  49  |1·4758|  75  |1·9740|  33  |0·8639|  59  |0·7487|
  |  24  |1·1875|  50  |1·4902|  76  |2·0000|  34  |0·8588|  60  |0·7449|
  |  25  |1·1968|  51  |1·4951|      |      |  35  |0·8538|  61  |0·7411|
  +------+------+------+------+------+------+------+------+------+------+


ARGILLACEOUS EARTH. The earth of clay, called in chemistry alumina,
because it is obtained in greatest purity from alum.


ARGOL. Crude _tartar_; which see.


ARMS. Weapons of war. See FIRE-ARMS for an account of this manufacture.


ARRACK. A kind of intoxicating beverage made in India, by distilling the
fermented juice of the cocoa-nut, the palmyra tree, and rice in the
husk.


ARROW ROOT. The root of the _maranta arundinacea_, a plant which grows
in the West Indies, furnishes, by pounding in mortars and elutriation
through sieves, a peculiar species of starch, commonly but improperly
called arrow root. It is reckoned more nourishing than the starch of
wheat or potatoes, and is generally also freer from peculiar taste or
flavour. The fresh root consists, according to Benzon, of 0·07 of
volatile oil; 26 of starch (23 of which are obtained in the form of
powder, while the other 3 must be extracted from the parenchyma in a
paste by boiling water); 1·58 of vegetable albumen; 0·6 of a gummy
extract; 0·25 of chloride of calcium; 6 of insoluble fibrine; and 65·6
of water.

The import duty upon arrow root from our own colonies, is 1_s._ per
cwt.; from foreign parts, 2_d._ per lib. In 1835, 987,966 lbs. were
imported, of which only 6267 were exported; leaving 895,406 for home
consumption. The total revenue derived that year from arrow root, was
518_l._ See STARCH.


ARSENIC. This metal occurs native, in the state of oxide, and also
combined with sulphur under the improper name of _yellow_ and _red
arsenic_, or orpiment and realgar. Arsenic is associated with a great
many metallic ores; but it is chiefly extracted from those of cobalt, by
roasting, in which case the white oxide of arsenic, or, more correctly,
the arsenious acid is obtained. This acid is introduced occasionally in
small quantities into the materials of flint glass, either before their
fusion, or in the melting pot. It serves to peroxidize the iron oxide in
the sand, and thereby to purify the body of the glass; but an excess of
it makes the glass milky.

_Scheele’s green_ is a combination of this arsenious acid with oxide of
copper, or an arsenite of copper, and is described under this metal.

_Arseniate of potash_ is prepared, in the small way, by exposing to a
moderate heat in a crucible, a mixture of equal parts of white arsenic
and nitre in powder. After fusion, the crucible is to be cooled; the
contents being dissolved in hot water, and the solution filtered, will
afford regular crystals on cooling. According to M. Berzelius, they are
composed of arsenic acid, 63·87; potash, 26·16; and water, 9·97. It is
an acidulous salt, and is hence usually called the binarseniate, to
denote that its composition is 2 atoms of arsenic acid, and 1 of potash.
This article is prepared upon the great scale, in Saxony, by melting
nitre and arsenious acid together in a cylinder of cast-iron. A neutral
arseniate also is readily formed, by saturating the excess of acid in
the above salt with potash; it does not crystallize. The acid arseniate
is occasionally used in calico printing, for preventing certain points
of the cotton cloth from taking on the mordant; with which view it is
mixed up with gum water and pipe clay into a paste, which is applied to
such places with a block.

The extraction of arsenic from the cobalt ores, is performed at
Altenberg and Reichenstein, in Silesia, with an apparatus, excellently
contrived to protect the health of the smelters from the vapours of this
most noxious metallic sublimate.

[Illustration: 20]

[Illustration: 23]

_Figs._ 20. to 23. represent the arsenical furnaces at Altenberg. _Fig._
20. is a vertical section of the poison tower; _fig._ 21., a
longitudinal section of the subliming furnace A, with the adjoining
vault B, and the poison tower in part at _n_; _fig._ 22., the transverse
section of the furnace A, of _fig._ 21.; _fig._ 23., ground plan of the
furnace A, where the left half shows the part above, and the right the
part below the muffle or oblong retort; B´ is the upper view, B´´ the
ground plan of the vault B, of _fig._ 21.; _m_, _n_, the base of the
poison tower. In the several figures the same letters denote the same
objects: _a_ is the muffle; _b_ is its mouth for turning over the
arsenical schlich, or ground ore; _c c c_, fire draughts or flues; _d_,
an aperture for charging the muffle with fresh schlich; _e_, the smoke
chimney; _f_, two channels or flues for the ascent of the arsenious
fumes, which proceed to other two flues _g_, and then terminate both in
_h_, which conducts the fumes into the vault B. They issue by the door
_i_, into the conduit _k_, thence by _l_ into the spaces _m_, _n_, _o_,
_p_, _q_, _r_, of the tower. The incondensable gases escape by the
chimney, _s_. The cover _t_, is removed after completion of the
process, in order to push down the precipitate into the lower
compartments.

[Illustration: 22 21]

The arsenious schlichs, to the amount of 9 or 10 cwt. for one operation
(1 _roast-post_, or roasting round), are spread 2 or 3 inches thick upon
the bottom of the muffle, heated with a brisk fire to redness, then with
a gentler heat, in order to oxidize completely, before subliming, the
arsenical ore. With this view the air must have free entrance, and the
front aperture of the muffle must be left quite open. After 11 or 12
hours, the calcined materials are raked out by the mouth of the muffle,
and fresh ones are introduced by the openings indicated above, which are
closed during the sublimation.

The arsenious acid found in these passages, is not marketable till it be
re-sublimed in large iron pots, surmounted with a series of sheet iron
drums or cast-iron cylinders, upon the sides of which the arsenic is
condensed in its compact glassy form. The top cylinder is furnished with
a pipe, which terminates in a condensing chamber.

[Illustration: 24]

_Figs._ 24, 25. represent the arsenic refining furnaces at Reichenstein.
_Fig._ 24. shows at A, a vertical section of the furnace, the kettle,
and the surmounting drums or cylinders; over B it is seen in elevation;
_fig._ 25. is a ground plan of the four fireplaces. _a_ is the grate;
_b_, the ash pit; _c_, the openings for firing; _d_, the fire-place;
_e_, iron pots or kettles which are charged with the arsenious powder;
_f_, the fire flues proceeding to the common chimney _g_; _h_, iron
cylinders; _i_, caps; _k_, pipes leading to the poison vent _l_; _m_,
openings in the pipes for introducing the probing wires.

[Illustration: 25]

The conduct of the process is as follows:--The pot is filled nearly to
its brim with 3-1/2 cwt. of the arsenic meal, the cylinders are fitted
on by means of their handles, and luted together with a mixture of loam,
blood, and hair; then is applied first a gentle, and after half an hour,
a strong fire, whereby the arsenic is raised partly in the form of a
white dust, and partly in crystals; which, by the continuance of the
heat, fuse together into a homogeneous mass. If the fire be too feeble,
only a sublimate is obtained; but, if too violent, much of the arsenic
is volatilized into the pipes. The workmen judge by the heat of the
cylinders whether the operation be going on well or not. After 12 hours
the furnace is allowed to cool, provided the probe wires show that the
sublimation is over. The cylinders are then lifted off, and the
arsenious glass is detached from their inner surface. According to the
quality of the poison-flour, it yields from 3/4 to 7/8 of its weight of
the glass or enamel. Should any dark particles of metallic arsenic be
intermixed with the glass, a fresh sublimation must be had recourse to.

The following is the product in cwts. of arsenious acid, at Altenberg
and Reichenstein, in Silesia, in the years

  +------------------+-----+-----+-----+-----+-----+-----+-----+-----+
  |                  |1825.|1826.|1827.|1828.|1829.|1830.|1831.|1832.|
  +------------------+-----+-----+-----+-----+-----+-----+-----+-----+
  |White arsenic in a|     |     |     |     |     |     |     |     |
  |glassy state      | 2632| 1703| 2686| 1900| 2070| 2961| 3337| 2730|
  |Sublimed arsenic  |     |     |     |     |     |     |     |     |
  |in powder         |   - |   27|   33|   31|   30|   44|   69|   38|
  |Yellow arsenical  |     |     |     |     |     |     |     |     |
  |glass             |  112|   11|   56|   - |   86|  313|   60|  219|
  |Red arsenical     |     |     |     |     |     |     |     |     |
  |glass             |    3|   - |   - |   - |   28|     |     |     |
  +------------------+-----+-----+-----+-----+-----+-----+-----+-----+


ARTESIAN WELLS. Under this name is designated a cylindrical perforation,
bored vertically down through one or more of the geological strata of
the earth, till it passes into a porous gravel bed containing water,
placed under such incumbent pressure as to make it mount up through the
perforation, either to the surface or to a height convenient for the
operation of a pump. In the first case, these wells are called spouting
or overflowing. This property is not directly proportional to the depth,
as might at first sight be supposed, but to the subjacent pressure upon
the water. We do not know exactly the period at which the borer or sound
was applied to the investigation of subterranean fountains, but we
believe the first overflowing wells were made in the ancient French
province of Artois, whence the name of Artesian. These wells, of such
importance to agriculture and manufactures, and which cost nothing to
keep them in condition, have been in use, undoubtedly, for several
centuries in the northern departments of France, and the north of Italy;
but it is not more than 50 or 60 years since they became known in
England and Germany. There are now a great many such wells in London and
its neighbourhood, perforated through the immensely thick bed of the
London clay, and even through some portions of the subjacent chalk. The
boring of such wells has given much insight into the geological
structure of many districts.

The formation of artesian wells depends on two things, essentially
distinct from each other: 1. On an acquaintance with the physical
constitution, or nature, of the mineral structure of each particular
country; and, 2. On the skilful direction of the processes by which we
can reach the water level, and of those by which we can promote its
ascent in the tube. We shall first treat of the best method of making
the well, and then offer some general remarks on the other subjects.

The operations employed for penetrating the soil are entirely similar to
those daily practised by the miner, in boring to find metallic veins;
but the well excavator must resort to peculiar expedients to prevent the
purer water, which comes from deep strata, mingling with the cruder
waters of the alluvial beds near the surface of the ground, as also to
prevent the small perforation getting eventually filled with rubbish.

The cause of overflowing wells has been ascribed to a variety of
circumstances. But, as it is now generally admitted that the numerous
springs which issue from the ground proceed from the infiltration of the
waters progressively condensed in rain, dew, snow, &c. upon the surface
of our globe, the theory of these interior streamlets becomes by no
means intricate; being analogous to that of syphons and water jets, as
expounded in the treatises of physics. The waters are diffused, after
condensation, upon the surface of the soil, and percolate downwards,
through the various pores and fissures of the geological strata, to be
again united subterraneously in veins, rills, streamlets, or expanded
films, of greater or less magnitude, or regularity. The beds traversed
by numerous disjunctions will give occasion to numerous interior
currents in all directions, which cannot be recovered, and brought to
the day; but when the ground is composed of strata of sand, or gravel
very permeable to water, separated by other strata nearly impervious to
it, reservoirs are formed to our hand, from which an abundant supply of
water may be spontaneously raised. In this case, as soon as the upper
stratum is perforated, the waters may rise, in consequence of the
hydrostatic pressure upon the lower strata, and even overflow the
surface in a constant stream, provided the level from which they proceed
be proportionally higher.

The sheets of water occur principally at the separation of two
contiguous formations; and, if the succession of the geological strata
be considered, this distribution of the water will be seen to be its
necessary consequence. In fact, the lower beds are frequently composed
of compact sandstone or limestone, and the upper beds of clay. In level
countries, the formations being almost always in horizontal-beds, the
waters which feed the artesian wells must come from districts somewhat
remote, where the strata are more elevated, as towards the secondary and
transition rocks. The copious streams condensed upon the sides of these
colder lands may be therefore regarded as the proper reservoirs of our
wells.

[Illustration: 26]

_Fig._ 26. represents the manner in which the condensed water of the
heavens distributes itself under the surface of our globe. Here we have
a geological section, showing the succession of the several formations,
and the sheets or laminæ of water that exist at their boundaries, as
well as in their sandy beds. The figure shows also very plainly that the
height to which the water reascends in the bore of a well depends upon
the height of the reservoir which supplies the sheet of water to which
the well is perforated. Thus the well A, having gone down to the aqueous
expanse A A, whose waters of supply are derived from the percolation M,
will afford rising waters, which will come to the surface; whilst in the
well B, supplied by the sheet P, the waters will spout above the
surface, and in the well C they will remain short of it. The same figure
shows that these wells often traverse sheets of water, which rise to
different heights. Thus, in the well C there are five columns of
ascending waters, which rise to heights proportional to the points
whence they take their origin. Several of these will be spouting or
overflowing, but some will remain beneath the surface.

[Illustration: 27]

The situation of the intended well being determined upon, a circular
hole is generally dug in the ground, about 6 or 8 feet deep, and 5 or 6
feet wide. In the centre of this hole the boring is carried on by two
workmen below, assisted by a labourer above, as shown in _fig._ 27.

[Illustration: 28 29]

The handle (_fig._ 28.) having a female screw in the bottom of its iron
shank, with a wooden bar or rail passing through the socket of the
shank, and a ring at top, is the general agent to which all the boring
implements are to be attached. A chisel (_fig._ 29.) is first employed,
and connected to this handle by its screw at top. If the ground is
tolerably soft, the weight of the two workmen bearing upon the cross
bar, and occasionally forcing it round, will soon cause the chisel to
penetrate; but if the ground is hard or strong, the workmen strike the
chisel down with repeated blows, so as to peck their way, often changing
their situation by walking round, which breaks the stones, or other hard
substances, that may happen to obstruct its progress.

The labour is very considerably reduced, by means of an elastic wooden
pole, placed horizontally over the well, from which a chain is brought
down, and attached to the ring of the handle. This pole is usually made
fast at one end, as a fulcrum, by being set into a heap of heavy loose
stones; at the other end the labourer above gives it a slight up and
down vibrating motion, corresponding to the beating motion of the
workmen below, by which means the elasticity of the pole in rising lifts
the handle and pecker, and thereby very considerably diminishes the
labour of the workmen. See _fig._ 27.

[Illustration: 30 31 32]

When the hole has been thus opened by a chisel, as far as its strength
would permit, the chisel is withdrawn, and a sort of cylindrical auger
(_fig._ 30.) attached to the handle (_fig._ 28.), for the purpose of
drawing up the dirt or broken stones which have been disturbed by the
chisel. A section of this auger is shown in _fig._ 31., by which the
internal valve will be seen. The auger being introduced into the hole,
and turned round by the workman, the dirt or broken stones will pass
through the aperture at bottom (shown at _fig._ 32.), and fill the
cylinder, which is then drawn up, and discharged at the top of the
auger, the valve preventing its escape at bottom.

[Illustration: 33 34 35 36 37]

In order to penetrate deeper into the ground, an iron rod, as _a_,
_fig._ 33., is now to be attached to the chisel, _fig._ 29., by screwing
on to its upper end, and the rod is also fastened to the handle, _fig._
28., by screwing into its socket. The chisel having thus become
lengthened, by the addition of the rod, it is again introduced into the
hole; and the operation of pecking or forcing it down, is carried on by
the workmen as before. When the ground has been thus perforated, as far
as the chisel and its rod will reach, they must be withdrawn, in order
again to introduce the auger, _fig._ 30., to collect and bring up the
rubbish; which is done by attaching it to the iron rod, in place of the
chisel. Thus as the hole becomes deepened, other lengths of iron rods
are added, by connecting them together, as _a b_ are in _fig._ 34. The
necessity of frequently withdrawing the rods from the holes, in order to
collect the mud, stones, or rubbish, and the great friction produced by
the rubbing of the tools against its sides, as well as the lengths of
rods augmenting in the progress of the operation, sometimes to the
extent of several hundred feet, render it extremely inconvenient, if not
impossible, to raise them by hand. A tripedal standard is, therefore,
generally constructed by three scaffolding poles tied together, over the
hole, as shown _fig._ 27., from the centre of which a wheel and axle, or
a pair of pully blocks is suspended, for the purpose of hauling up the
rods, and from which hangs the fork, _fig._ 35. This fork is to be
brought down under the shoulder, near the top of each rod, and made fast
to it by passing a pin through two little holes in the claws. The rods
are thus drawn up, about seven feet at a time, which is the usual
distance between each joint, and at every haul a fork, _fig._ 36., is
laid horizontally over the hole, with the shoulders of the lower rod
resting between its claws, by which means the rods are prevented from
sinking down into the hole again, while the upper length is unscrewed
and removed. In attaching and detaching these lengths of rod, a wrench,
_fig._ 37., is employed, by which they are turned round, and the screws
forced up to their firm bearing.

[Illustration: 38]

The boring is sometimes performed for the first sixty or a hundred feet,
by a chisel of 2-1/2 inches wide, and cleared out by a gouge of 2-1/4
diameter, and then the hole is widened by a tool, such as is shown at
_fig._ 38. This is merely a chisel, as _fig._ 29., four inches wide, but
with a guide, _a_, put on at its lower part, for the purpose of keeping
it in a perpendicular direction; the lower part is not intended to peck,
but to pass down the hole previously made, while the sides of the chisel
operate in enlarging the hole to four inches. The process, however, is
generally performed at one operation, by a chisel of four inches wide,
as _fig._ 29., and a gouge of three inches and three quarters, as _fig._
30.

It is obvious, that placing and displacing the lengths of rod, which is
done every time that the auger is required to be introduced or
withdrawn, must, of itself, be extremely troublesome, independent of the
labour of boring, but yet the operation proceeds, when no unpropitious
circumstances attend it, with a facility almost incredible. Sometimes,
however, rocks intercept the way, which require great labour to
penetrate; but this is always effected by pecking, which slowly
pulverises the stone. The most unpleasant circumstance attendant upon
this business is the occasional breaking of a rod into the hole, which
sometimes creates a delay of many days, and an incalculable labour in
drawing up the lower portion.

When the water is obtained in such quantities and of such quality as may
be required, the hole is dressed or finished by passing down it a
diamond chisel, funnel mouthed, with a triangular bit in its centre;
this makes the sides smooth previous to putting in the pipe. This chisel
is attached to rods, and to the handle, as before described; and, in its
descent, the workmen continually walk round, by which the hole is made
smooth and cylindrical. In the progress of the boring, frequent veins of
water are passed through; but, as these are small streams, and perhaps
impregnated with mineral substances, the operation is carried on until
an aperture is made into a main spring, which will flow up to the
surface of the earth. This must, of course, depend upon the level of its
source, which, if in a neighbouring hill, will frequently cause the
water to rise up, and produce a continued fountain. But if the altitude
of the distant spring happens to be below the level of the surface of
the ground where the boring is effected, it sometimes happens that a
well of considerable capacity is obliged to be dug down to that level,
in order to form a reservoir, into which the water may flow, and whence
it must be raised by a pump; while, in the former instance, a perpetual
fountain may be obtained. Hence, it will always be a matter of doubt, in
level countries, whether water can be procured, which would flow near to
or over the surface; if this cannot be effected, the process of boring
will be of little or no advantage, except as an experiment to ascertain
the fact.

In order to keep the strata pure, and uncontaminated with mineral
springs, the hole is cased, for a considerable depth, with a metallic
pipe, about a quarter of an inch smaller than the bore. This is
generally made of tin (though sometimes of copper or lead) in convenient
lengths; and, as each length is let down, it is held by a shoulder
resting in a fork, while another length is soldered to it; by which
means a continuous pipe is carried through the bore, as far as may be
found necessary, to exclude land springs, and to prevent loose earth or
sand from falling in, and choking the aperture.

Mr. John Good, of Tottenham, who had been extensively employed in boring
the earth for water, obtained a patent, in Aug. 1823, for certain
improved implements contrived by him to facilitate his useful labours; a
description of which cannot fail to be interesting.

[Illustration: 39 40 41 42]

The figures annexed exhibit these ingenious tools; _fig._ 39. is an
auger, to be connected by the screw-head to the length of rods by which
the boring is carried on. This auger is for boring in soft clay or sand;
it is cylindrical, and has a slit or opening from end to end, and a bit,
or cutting-piece at bottom. When the earth is loose or wet, an auger of
the same form is to be employed, but the slit or opening reduced in
width, or even without a slit or opening. A similar auger is used for
cutting through chalk; but the point or bit at bottom should then
project lower, and, for that purpose, some of these cylindrical augers
are made with moveable bits, to be attached by screws, which is
extremely desirable in grinding them to cutting edges. _Fig._ 40. is a
hollow conical auger, for boring loose sandy soils; it has a spiral
cutting edge coiled round it, which, as it turns, causes the loose soil
to ascend up the inclined plane, and deposit itself in the hollow
within. _Fig._ 41. is a hollow cylinder or tube, shown in section, with
a foot-valve, and a bucket to be raised by a rod and cord attached at
the top; this is a pumping tool, for the purpose of getting up water and
sand that would not rise by the auger. When this cylinder is lowered to
the bottom of the bore, the bucket is lifted up by the rod and cord, and
descends again by its own gravity, having a valve in the bucket, opening
upwards, like other lift pumps; which, at every stroke, raises a
quantity of water and sand in the cylinder equal to the stroke; the
ascent and descent of the bucket being limited by a guide-piece at the
top of the cylinder, and two small knobs upon the rod, which stop
against the cross-guide. _Fig._ 42. is a tool for getting up broken
rods. It consists of a small cylindrical piece at bottom, which the
broken rod slips through when it is lowered, and a small catch with a
knife-edge, acted upon by a back-spring. In rising, the tool takes hold
of the broken rod, and thereby enables the workmen at top to draw it up.
Another tool for the same purpose, is shown at _fig._ 43., which is like
a pair of tongs; it is intended to be slidden down the bore, and for the
broken rod to pass between the two catches, which, pressed by
back-springs, will, when drawn up, take fast hold of the broken rod.

[Illustration: 43 44 45 46]

_Fig._ 44. is a tool for widening the hole, to be connected, like all
the others, to the end of the length of rods passed down the bore; this
tool has two cutting-pieces extending on the sides at bottom, by which,
as the tool is turned round in the bore, the earth is peeled away.
_Fig._ 45. is a chisel, or punch, with a projecting piece to be used for
penetrating through stone; this chisel is, by rising and falling, made
to peck the stone, and pulverize it; the small middle part breaking it
away first, and afterwards the broad part coming into action. _Fig._ 46.
is another chisel, or punching tool, twisted on its cutting edge, which
breaks away a greater portion of the stone as it beats against it.

[Illustration: 47 48 49]

The manner of forcing down lengths of cast-iron pipe, after the bore is
formed, is shown at _fig._ 47.; the pipe is seen below in the socket, at
the end of which a block is inserted; and from this block a rod extends
upwards, upon which a weight at top slides. To this weight cords are
shown to be attached, reaching to the top of the bore; where the workmen
alternately raise the weight and let it fall, which, by striking upon
the block in its middle, beats down the pipe by a succession of strokes;
and when one length of pipe has, by these means, been forced down,
another length is introduced into the socket of the former. Another
tool for the same purpose is shown at _fig._ 48., which is formed like
an acorn; the raised part of the acorn strikes against the edge of the
pipe, and by that means, it is forced down the bore. When it happens
that an auger breaks in the hole, a tool similar to that shown at _fig._
49. is introduced; on one side of this tool a curved piece is attached,
for the purpose of a guide, to conduct it past the cylindrical auger;
and at the end of the other side is a hook, which, taking hold of the
bottom edge of the auger, enables it to be drawn up.

[Illustration: 50 51 52]

Wrought iron, copper, tin, and lead pipes, are occasionally used for
lining the bore; and as these are subject to bends and bruises, it is
necessary to introduce tools for the purpose of straightening their
sides. One of these tools is shown at _fig._ 50., which is a bow, and is
to be passed down the inside of the pipe, in order to press out any
dents. Another tool, for the same purpose, is shown at _fig._ 51., which
is a double bow, and may be turned round in the pipe for the purpose of
straightening it all the way down; at _fig._ 52., is a pair of clams,
for turning the pipe round in the hole while driving.

[Illustration: 53 54]

When loose stones lie at the bottom of the hole, which are too large to
be brought up by the cylindrical auger, and cannot be conveniently
broken, then it is proposed to introduce a triangular claw, as _fig._
53., the internal notches of which take hold of the stone, and as the
tool rises, bring it up. For raising broken rods, a tool like _fig._ 54.
is sometimes employed, which has an angular claw that slips under the
shoulder of the rod, and holds it fast while drawing up.

[Illustration: 55 56]

In raising pipes, it is necessary to introduce a tool into the inside of
the pipe, by which it will be held fast. _Fig._ 55. is a pine-apple tool
for this purpose; its surface is cut like a rasp, which passes easily
down into the pipe, but catches as it is drawn up; and by that means
brings the pipe with it. _Fig._ 56. is a spear for the same purpose,
which easily enters the pipe by springing; at the ends of its prongs
there are forks which stick into the metal as it is drawn up, and
thereby raise it.

These are the new implements, for which the patent was granted. In the
process of boring, there does not appear to be any thing new proposed;
but that these several tools are to be employed for boring, packing, and
otherwise penetrating, raising the earth, and extracting broken or
injured tools. There are also suggestions for employing long buckets,
with valves opening upward in their bottoms, for the purpose of drawing
water from these wells when the water will not flow over the surface;
also lift pumps, with a succession of buckets for the same purpose. But
as these suggestions possess little if any novelty, it cannot be
intended to claim them as parts of the patent.


ASPHALTUM. Native bitumen, so called from the lake Asphaltites.


ASSAY and ASSAYING. (_Coupellation_, Fr.; _Abtreiben auf der capelle_,
Germ.) This is the process by which the quality of gold and silver
bullion, coin, plate, or trinkets is ascertained with precision, or by
which the quantity of either or both these precious metals is determined
in any given alloy. It is, therefore, a case of chemical analysis, in
which peculiar methods are employed to attain the object in view with
accuracy and dispatch. Assaying has been also extended of late years, to
determine the quantity of palladium and platina in certain bullion and
gold dust brought from Brazil.

The art of assaying gold and silver _by the cupel_, is founded upon the
feeble affinity which these metals have for oxygen, in comparison with
copper, tin, and the other cheaper metals; and on the tendency which the
latter metals have to oxidize rapidly in contact with lead at a high
temperature, and sink with it into any porous earthy vessel in a thin
glassy or vitriform state. The porous vessel may be made either of
wood-ashes, freed from their soluble matter by washing with water; or,
preferably, of burned bones reduced to a fine powder.

The lead added to the silver or gold to be assayed, serves chiefly to
dissolve the oxidized copper, whence it appears that the quantity of
lead requisite for silver assays, ought to be directly proportional to
the quantity which the silver and copper would separately require. It
has been found by experiment, that 16 parts of lead are quite sufficient
to pass 1 of copper through the cupel; and that 3/10 of lead presents
the most suitable proportion for passing one of silver. From these
principles, however, if we should always regard the dose of lead to be
employed for any alloy as being equal to (16 × C) + (3/30 × S) we should
certainly commit an error. The phenomena of cupellation is of a more
complex nature. Long practice and delicate trials alone can guide to the
proper quantity of lead to be employed for every various state of the
alloy. The following Table contains the results of M. D’Arcet’s
elaborate experiments upon this subject:--

  +---------------+--------+-------------+
  |     Alloy.    |Lead for|Ratio of the |
  +-------+-------+  1 of  |Copper to the|
  |Silver.|Copper.| Alloy. |    Lead.    |
  +-------+-------+--------+-------------+
  | 1000  |    0  |    3/10|   0         |
  |  950  |   50  |    3   |   1 : 60    |
  |  900  |  100  |    7   |   1 : 70    |
  |  800  |  200  |   10   |   1 : 50    |
  |  700  |  300  |   12   |   1 : 40    |
  |  600  |  400  |   14   |   1 : 35    |
  |  500  |  500  |16 or 17|   1 : 32    |
  |  400  |  600  |16 -- 17|   1 : 26·7  |
  |  300  |  700  |16 -- 17|   1 : 22·9  |
  |  200  |  800  |16 -- 17|   1 : 20    |
  |  100  |  900  |16 -- 17|   1 : 17·8  |
  |    0  | 1000  |16 -- 17|   1 : 16    |
  +-------+-------+--------+-------------+

Bismuth may be used as a substitute for lead in cupellation; two parts
of it being nearly equivalent to three of lead. But its higher prices
will prevent its general introduction among assay masters.

We begin this assay process by weighing, in a delicate balance, a
certain weight of the metallic alloy; a gramme (= 15·444 gr.) is usually
taken in France, and 12 grains in this country. This weight is wrapped
up in a slip of lead foil or paper, should it consist of several
fragments. This small parcel, thus enveloped, is then laid in a watch
glass or a capsule of copper, and there is added to it the proportion of
lead suited to the quality of alloy to be assayed; there being less
lead, the finer the silver is presumed to be. Those who are much in the
habit of cupellation can make good guesses in this way; though it is
still guess work, and often leads to considerable error, for if too much
lead be used for the proportion of baser metal present, a portion of the
silver is wasted; but if too little, then the whole of the copper, &c.
is not carried off, and the button of fine silver remains more or less
impure. The most expert and experienced assayer by the cupel, produces
merely a series of approximate conjectural results, which fall short of
chemical demonstration and certainty in every instance. The lead must
be, in all cases, entirely free from silver, being such as has been
revived from pure litharge; otherwise errors of the most serious kind
would be occasioned in the assays.

The best cupels weigh 12-1/2 grammes, or 193 grains. The cupels allow
the fused oxides to flow through them as through a fine sieve, but are
impermeable to the particles of metals; and thus the former pass readily
down into their substance while the latter remain upon their surface; a
phenomenon owing to the circumstance of the glassy oxides moistening, as
it were, the bone-ash powder, whereas the metals can contract no
adherence with it. Hence also the liquid metals preserve a hemispherical
shape in the cupels, as quicksilver does in a cup of glass, while the
fused oxide spreads over, and penetrates their substance, like water. A
cupel may be regarded, in some measure, as a filter permeable only to
certain liquids.

If we put into a cupel, therefore, two metals, of which the one is
unalterable in the air, the other susceptible of oxidizement, and of
producing a very fusible oxide, it is obvious that, by exposing both to
a proper degree of heat, we shall succeed in separating them. We should
also succeed, though the oxide were infusible, by placing it in contact
with another one, which may render it fusible. In both cases, however,
the metal from which we wish to part the oxides must not be volatile; it
should also melt, and form a button at the heat of cupellation; for
otherwise it would continue disseminated, attached to the portion of
oxide spread over the cupel, and incapable of being collected.

The furnace and implements used for assaying in the Royal Mint and the
Goldsmiths’ Hall, in the city of London, are the following:--

[Illustration: 58 59]

A A A A, _fig._ 58., is a front elevation of an assay furnace; _a a_, a
view of one of the two iron rollers on which the furnace rests, and by
means of which it is moved forward or backward; _b_, the ash-pit; _c c_
are the ash-pit dampers, which are moved in a horizontal direction
towards each other for regulating the draught of the furnace; _d_, the
door, or opening, by which the cupels and assays are introduced into the
muffle; _e_, a moveable funnel or chimney by which the draught of the
furnace is increased. B B B B, _fig._ 59., is a perpendicular section
of _fig._ 58.; _a a_, end view of the rollers; _b_ the ash-pit; _c_ one
of the ash-pit dampers; _d_ the grate, over which is the plate upon
which the muffle rests, and which is covered with loam nearly one inch
thick; _f_ the muffle in section representing the situation of the
cupels; _g_ the mouth-plate, and upon it are laid pieces of charcoal,
which during the process are ignited, and heat the air that is allowed
to pass over the cupels, as will be more fully explained in the sequel;
_h_ the interior of the furnace, exhibiting the fuel.

The total height of the furnace is 2 feet 6-1/2 inches; from the bottom
to the grate, 6 inches; the grate, muffle, plate, and bed of loam, with
which it is covered, 3 inches; from the upper surface of the grate to
the commencement of the funnel _e_, _fig._ 58., 21-1/2 inches; the
funnel _e_, 6 inches. The square of the furnace which receives the
muffle and fuel is 11-3/4 inches by 15 inches. The external sides of the
furnace are made of plates of wrought iron, and are lined with a 2-inch
fire-brick.

[Illustration: 60]

C C C C, _fig._ 60., is a horizontal section of the furnace over the
grate, showing the width of the mouth-piece, or plate of wrought iron,
which is 6 inches, and the opening which receives the muffle-plate.

[Illustration: 61]

_Fig._ 61. represents the muffle or pot, which is 12 inches long, 6
inches broad inside; in the clear 6-3/4: in height 4-1/2 inside measure,
and nearly 5-1/2 in the clear.

[Illustration: 62]

_Fig._ 62., the muffle-plate, which is of the same size as the bottom of
the muffle.

[Illustration: 63]

_Fig._ 63. is a representation of the sliding-door of the mouth-plate,
as shewn at _d_, in _fig._ 58.

[Illustration: 64]

_Fig._ 64., a front view of the mouth-plate or piece, _d_, _fig._ 58.

[Illustration: 65]

_Fig._ 65., a representation of the mode of making, or shutting up with
pieces of charcoal, the mouth of the furnace.

_Fig._ 66., the teaser for cleaning the grate.

[Illustration: 66 67 68]

_Fig._ 67., a larger teaser, which is introduced at the top of the
furnace, for keeping a complete supply of charcoal around the muffle.

_Fig._ 68., the tongs used for charging the assays into the cups.

[Illustration: 69]

_Fig._ 69. represents a board of wood used as a register, and is divided
into 45 equal compartments, upon which the assays are placed previously
to their being introduced into the furnace. When the operation is
performed, the cupels are placed in the furnace in situations
corresponding to these assays on the board. By these means all confusion
is avoided, and without this regularity it would be impossible to
preserve the accuracy which the delicate operations of the assayer
require.

[Illustration: 70 71 72]

I shall now proceed to a description of a small assay furnace, invented
by Messrs. Anfrye and d’Arcet, of Paris. They term it, _Le Petit
Fourneau à Coupelle_. _Fig._ 70. represents this furnace, and it is
composed of a chimney or pipe of wrought iron _a_, and of the furnace B.
It is 17-1/2 inches high, and 7-1/4 inches wide. The furnace is formed
of three pieces; of a dome A; the body of the furnace B; and the ash-pit
C, which is used as the base of the furnace, _fig._ 70. and 71. The
principal piece, or body of the furnace, B, has the form of a hollow
tower, or of a hollow cylinder, flattened equally at the two opposite
sides parallel to the axis, in such a manner that the horizontal section
is elliptical. The foot which supports it is a hollow truncated cone,
flattened in like manner upon the two opposite sides, and having
consequently for its basis two ellipses of different diameters; the
smallest ought to be equal to that of the furnace, so that the bottom of
the latter may exactly fit it. The dome, which forms an arch above the
furnace, has also its base elliptical, whilst that of the superior
orifice by which the smoke goes out preserves the cylindrical form. The
tube of wrought iron is 18 inches long and 2-1/2 inches diameter, having
one of its ends a little enlarged, and slightly conical, that it may be
exactly fitted or jointed upon the upper part of the furnace dome _d_,
_fig._ 70. At the union of the conical and cylindrical parts of the
tube, there is placed a small gallery of iron, _e_, _fig._ 70, 71. See
also a plan of it, _fig._ 72. This gallery is both ingenious and useful.
Upon it are placed the cupels, which are thus annealed during the
ordinary work of the furnace, that they may be introduced into the
muffle, when it is brought into its proper degree of heat. A little
above this gallery is a door _f_, by which, if thought proper, the
charcoal could be introduced into the furnace; above that there is
placed at _g_ a throttle valve, which is used for regulating the draught
of the furnace at pleasure. Messrs. Anfrye and d’Arcet say, that, to
give the furnace the necessary degree of heat so as to work the assays
of gold, the tube must be about 18 inches above the gallery, for
annealing or heating the cupels. The circular opening _h_, in the dome,
_fig._ 70., and as seen in the section, _fig._ 71., is used to introduce
the charcoal into the furnace: it is also used to inspect the interior
of the furnace, and to arrange the charcoal round the muffle. This
opening is kept shut during the working of the furnace, with the
mouth-piece, of which the face is seen at _n_, _fig._ 71.

The section of the furnace, _fig._ 71., presents several openings, the
principal of which is that of the muffle; it is placed at _i_; it is
shut with the semicircular door _m_, _fig._ 70., and seen in the section
_m_, _fig._ 71. In front of this opening, is the table or shelf, upon
which the door of the muffle is made to advance or recede; the letter
_q_, _fig._ 71., shows the face, side, and cross section of the shelf,
which makes part of the furnace. Immediately under the shelf, is a
horizontal slit, _l_, which is pierced at the level of the upper part of
the grate, and used for the introduction of a slender rod of iron, that
the grate may be easily kept clean. This opening is shut at pleasure, by
the wedge represented at _k_, _fig._ 70. and 71.

Upon the back of the furnace is a horizontal slit _p_, _fig._ 71, which
supports the fire-brick, _s_, and upon which the end of the muffle, if
necessary, may rest; _u_, _fig._ 71., is the opening in the furnace
where the muffle is placed.

[Illustration: 73]

The plan of the grate of the furnace is an ellipse: _fig._ 73. is a
horizontal view of it. The dimensions of that ellipsis determine the
general form of the furnace, and thickness of the grate. To give
strength and solidity to the grate, it is encircled by a bar or hoop of
iron. There is a groove in which the hoop of iron is fixed. The holes of
the grate are truncated cones, having the greater base below, that the
ashes may more easily fall into the ash-pit. The letter _v_, _fig._ 71.,
shows the form of these holes. The grate is supported by a small bank or
shelf, making part of the furnace, as seen at _a_, _fig._ 71.

The ash-pit, C, has an opening _y_ in front, _fig._ 71.; and is shut
when necessary by the mouth-piece _r_, _fig._ 70. and 71.

To give strength and solidity to the furnace, it is bound with hoops of
iron, at _b_, _b_, _b_, _b_, _fig._ 70.

[Illustration: 74 75 76]

_Figs._ 74. 75. 76. are views of the muffle.

_Fig._ 77. is a view of a crucible for annealing gold.

[Illustration: 77 78 79 80]

_Figs._ 78. 79. 80. are cupels of various sizes, to be used in the
furnace. They are the same as those used by assayers in their ordinary
furnaces.

[Illustration: 81 82]

_Figs._ 81. and 82. are views of the hand-shovels, used for filling the
furnace with charcoal; they should be made of such size and form as to
fit the opening _h_, in _figs._ 70. and 71.

The smaller pincers or tongs, by which the assays are charged into the
cupels, and by which the latter are withdrawn from the furnace, as well
as the teaser for cleaning the grate of the furnace, are similar to
those used in the British Mint.

In the furnace of the Mint above described, the number of assays that
can be made at one time, is 45. The same number of cupels are put into
the muffle. The furnace is then filled with charcoal to the top, and
upon this are laid a few pieces already ignited. In the course of three
hours, a little more or less, according to circumstances, the whole is
ignited; during which period, the muffle, which is made of fire-clay, is
gradually heated to redness, and is prevented from cracking; which a
less regular or more sudden increase of temperature would not fail to
do: the cupels, also, become properly annealed. All moisture being
dispelled, they are in a fit state to receive the piece of silver or
gold to be assayed.

The greater care that is exercised in this operation, the less liable is
the assayer to accidents from the breaking of the muffle; which it is
both expensive and troublesome to fit properly into the furnace.

The cupels used in the assay process, are made of the ashes of burnt
bones (phosphate of lime). In the Royal Mint, the cores of ox-horn are
selected for this purpose; and the ashes produced are about four times
the expense of the bone-ash, used in the process of cupellation upon the
large scale. So much depends upon the accuracy of an assay of gold or
silver, where a mass of 15lbs. troy in the first, and 60lbs. troy in the
second instance, is determined by the analysis of a portion not
exceeding 20 troy grains, that every precaution which the longest
experience has suggested, is used to obtain an accurate result. Hence
the attention paid to the selection of the most proper materials for
making the cupels.

The cupels are formed in a circular mould made of cast steel, very
nicely turned, by which means they are easily freed from the mould when
struck. The bone-ash is used moistened with a quantity of water,
sufficient to make the particles adhere firmly together. The circular
mould is filled, and pressed level with its surface; after which, a
pestle or rammer, having its end nicely turned, of a globular or convex
shape, and of a size equal to the degree of concavity wished to be made
in the cupel for the reception of the assay, is placed upon the ashes in
the mould, and struck with a hammer until the cupel is properly formed.
These cupels are allowed to dry in the air for some time before they are
used. If the weather is fine, a fortnight will be sufficient.

An assay may prove defective for several reasons. Sometimes the button
or bead sends forth crystalline vegetations on its surface with such
force, as to make one suppose a portion of the silver may be thrown out
of the cupel. When the surface of the bead is dull and flat, the assay
is considered to have been too hot, and it indicates a loss of silver in
fumes. When the tint of the bead is not uniform, when its inferior
surface is bubbly, when yellow scales of oxide of lead remain on the
bottom of the cupel, and the bead adheres strongly to it, by these signs
it is judged that the assay has been too cold, and that the silver
retains some lead.

Lastly, the assay is thought to be good if the bead is of a round form,
if its upper surface is brilliant, if its lower surface is granular and
of a dead white, and if it separates readily from the cupel.

After the lead is put into the cupel, it gets immediately covered with a
coat of oxide, which resists the admission of the silver to be assayed
into the melted metal; so that the alloy cannot form. When a bit of
silver is laid on a lead bath in this predicament, we see it swim about
for a long time without dissolving. In order to avoid this result, the
silver is wrapped up in a bit of paper; and the carburetted hydrogen
generated by its combustion, reduces the film of the lead oxide, gives
the bath immediately a bright metallic lustre, and enables the two
metals readily to combine.

As the heat rises, the oxide of lead flows round about over the surface,
till it is absorbed by the cupel. When the lead is wasted to a certain
degree, a very thin film of it only remains on the silver, which causes
the iridescent appearance, like the colours of soap-bubbles; a
phenomenon, called by the old chemists, fulguration.

When the cupel cools in the progress of the assay, the oxygenation of
the lead ceases; and, instead of a very liquid vitreous oxide, an
imperfectly melted oxide is formed, which the cupel cannot absorb. To
correct a cold assay, the temperature of the furnace ought to be raised,
and pieces of paper ought to be put into the cupel, till the oxide of
lead which adheres to it, be reduced. On keeping up the heat, the assay
will resume its ordinary train.

Pure silver almost always vegetates. Some traces of copper destroy this
property, which is obviously due to the oxygen which the silver can
absorb while it is in fusion, and which is disengaged the moment it
solidifies. An excess of lead, by removing all the copper at an early
stage, tends to cause the vegetation.

The brightening is caused by the heat evolved, when the button passes
from the liquid to the solid state. Many other substances present the
same phenomenon.

In the above operation it is necessary to employ lead which is very
pure, or at least free from silver. That kind is called _poor lead_.

It has been observed at all times, that the oxide of lead carries off
with it, into the cupel, a little silver in the state of an oxide. This
effect becomes less, or even disappears, when there is some copper
remaining; and the more copper, the less chance there is of any silver
being lost. The loss of silver increases, on the other hand, with the
dose of lead. Hence the reason why it is so important to proportion the
lead with a precision which, at first sight, would appear to be
superfluous. Hence, also, the reason of the attempts which have, of late
years, been made to change the whole system of silver assays, and to
have recourse to a method exempt from the above causes of error.

M. d’Arcet, charged by the Commission of the Mint in Paris, to examine
into the justice of the reclamations made by the French silversmiths
against the public assays, ascertained that they were well founded; and
that the results of cupellation gave for the alloys between 897 and 903
thousandths (the limits of their standard coin) an inferior standard, by
from 4 to 5 thousandth parts, from the standard or title which should
result from the absolute or actual alloy.

The mode of assay shows, in fact, that an ingot, experimentally composed
of 900 thousandths of fine silver, and 100 thousandths of copper,
appears, by cupellation, to be only, at the utmost, 896 or 897
thousandths; whereas fine silver, of 1000 thousandths, comes out nearly
of its real standard. Consequently a director of the Mint, who should
compound his alloy with fine silver, would be obliged to employ 903 or
904 thousandths, in order that, by the assay in the laboratory of the
Mint, it should appear to have the standard of 900 thousandths. These 3
or 4 thousandths would be lost to him, since they would be disguised by
the mode of assay, the definitive criterion of the quantity of silver,
of which the government keeps count from the coiner of the money.

From experiments subsequently made by M. d’Arcet, it appears that silver
assays always suffer a loss of the precious metal, which varies,
however, with the standard of the alloy. It is 1 thousandth for fine
silver,

  4·3 thousandths for silver of 900 thousandths,
  4·9     --      for   --   of 800     --
  4·2     --      for   --   of 500     --

and diminishes thereafter, progressively, till the alloy contains only
100 thousandths of silver, at which point the loss is only 0·4.

Assays requested by the Commission of the Paris Mint, from the assayers
of the principal Royal Mints in Europe, to which the same alloys,
synthetically compounded, were sent, afforded the results inscribed in
the following table.

  +----------------------+----------+-----------------------------+
  |                      |          |   Standards found for the   |
  |                      |  Cities  |    Mathematical Alloys.     |
  |Names of the Assayers.|where they+---------+---------+---------+
  |                      | reside.  |950 mill.|900 mill.|800 mill.|
  +----------------------+----------+---------+---------+---------+
  |F. de Castenhole, Mint|          |         |         |         |
  |Assayer               |Vienna    |946·20   |898·40   |795·10   |
  |A. R. Vervaëz, Ditto  |Madrid    |944·40   |893·70   |789·20   |
  |D. M. Cabrera, Assayer|          |         |         |         |
  |in Spain              |Ditto     |944·40   |893·70   |788·60   |
  |Assayer               |Amsterdam |947·00   |895·00   |795·00   |
  |Mr. Bingley, Assay    |          |         |         |         |
  |Master                |London    |946·25   |896·25   |794·25   |
  |Mr. Johnson, Assayer  |Ditto     |933·33   |883·50   |783·33   |
  |Inspector of the Mint |Utrecht   |945·00   |896·50   |799·00   |
  |Assayer of the Mint   |Naples    |945·00   |891·00   |787·00   |
  |Assayer of Trade      |Ditto     |945·00   |891·00   |787·00   |
  |Assayer of the Mint   |Hamburgh  |946·13/72|897·41/72|798·44/72|
  |Ditto                 |Altona    |942·1/4  |894·00   |790      |
  +----------------------+----------+---------+---------+---------+

These results, as well as those in still greater numbers, obtained from
the ablest Parisian assayers, upon identical alloys of silver and
copper, prove that the mode of assay applied to them brings out the
standard too low; and further, that the quantity of silver masked or
disguised, is not uniform for these different eminent assay masters. An
alloy, for example, at the standard of 900 thousandths is judged at

                                           M.
  the Mint of Paris to have a standard of 895·6
  At that of Vienna           --          898·4
     --      Madrid           --          893·7
     --      Naples           --          891·0

The fact thus so clearly made out of a loss in the standard of silver
bullion and coin, merits the most serious attention; and it will appear
astonishing, perhaps, that a thing recurring every day, should have
remained for so long a time in the dark. In reality, however, the fact
is not new; as the very numerous and well-made experiments of Tillet
from 1760 to 1763, which are related in the memoirs of the Academy of
Sciences, show, in the silver assays, a loss still greater than that
which was experienced lately in the laboratory of the Commission of the
French Mint. But he thought that, as the error was common to the nations
in general, it was not worth while or prudent to introduce any
innovation.

A mode of assaying, to give, with certainty, the standard of silver
bullion, should be entirely independent of the variable circumstances of
temperature, and the unknown proportions of copper, so difficult to
regulate by the mere judgment of the senses. The process by the humid
way, recommended by me to the Royal Mint in 1829, and exhibited as to
its principles before the Right Honourable John Herries, then Master, in
1830, has all the precision and certainty we could wish. It is founded
on the well-known property which silver has, when dissolved in nitric
acid, to be precipitated in a chloride of silver quite insoluble, by a
solution of sea salt, or by muriatic acid; but, instead of determining
the weight of the chloride of silver, which would be somewhat uncertain
and rather tedious, on account of the difficulty of drying it, we take
the quantity of the solution of sea salt which has been necessary for
the precipitation of the silver. To put the process in execution, a
liquor is prepared, composed of water and sea salt in such proportions
that 1000 measures of this liquor may precipitate, completely, 12 grains
of silver, perfectly pure, or of the standard 1000, previously dissolved
in nitric acid. The liquor thus prepared, gives, immediately, the true
standard of any alloy whatever, of silver and copper, by the weight of
it which may be necessary to precipitate 12 grains of this alloy. If,
for example 905 measures have been required to precipitate the 12 grains
of alloy, its standard would be 905 thousandths.

The process by the humid way is, so to speak, independent of the
operator. The manipulations are so easy; and the term of the operation
is very distinctly announced by the absence of any sensible nebulosities
on the affusion of sea salt into the silver solution, while there
remains in it 1/2 thousandth of metal. The process is not tedious, and
in experienced hands it may rival the cupel in rapidity; it has the
advantage over the cupel of being more within the reach of ordinary
operators, and of not requiring a long apprenticeship. It is
particularly useful to such assayers as have only a few assays to make
daily, as it will cost them very little time and expense.

By agitating briskly during two minutes, or thereby, the liquid rendered
milky by the precipitation of the chloride of silver, it may be
sufficiently clarified to enable us to appreciate, after a few moments
of repose, the disturbance that can be produced in it by the addition of
1000 of a grain of silver. Filtration is more efficacious than
agitation, especially when it is employed afterwards; it may be
sometimes used; but agitation, which is much more prompt, is generally
sufficient. The presence of lead and copper, or any other metal, except
mercury, has no perceptible influence on the quantity of sea salt
necessary to precipitate the silver; that is to say, the same quantity
of silver, pure or alloyed, requires for its precipitation a constant
quantity of the solution of sea salt.

Supposing that we operate upon a gramme of pure silver, the solution of
sea salt ought to be such that 100 centimetres cube may precipitate
exactly the whole silver. The standard of an alloy is given by the
number of thousandths of solution of sea salt necessary to precipitate
the silver contained in a gramme of the alloy.

When any mercury is accidentally present, which is, however, a rare
occurrence, it is made obvious by the precipitated chloride remaining
white when exposed to daylight, whereas when there is no mercury
present, it becomes speedily first grey and then purple. Silver so
contaminated must be strongly ignited in fusion before being assayed,
and its loss of weight noted. In this case, a cupel assay must be had
recourse to.

_Preparation of the Normal Solution of Sea Salt, when it is measured by
Weight._--Supposing the sea salt pure as well as the water, we have only
to take these two bodies in the proportion of 0·5427 k. of salt to
99·4573 k. of water, to have 100 k. of solution, of which 100 grammes
will precipitate exactly one gramme of silver. But instead of pure salt,
which is to be procured with difficulty, and which besides may be
altered readily by absorbing the humidity of the air, a concentrated
solution of the sea salt of commerce is to be preferred, of which a
large quantity may be prepared at a time, to be kept in reserve for use,
as it is wanted. _Instruction de Gay Lussac._

_Preparation of the Normal Solution of Sea Salt, when measured by
Volume._--The measure by weight has the advantage of being independent
of temperature, of having the same degree of precision as the balance,
and of standing in need of no correction. The measure by volume has not
all these advantages; but, by giving it sufficient precision, it is more
rapid, and is quite sufficient for the numerous daily assays of the
mint. This normal solution is so made, that a volume equal to that of
100 grammes of water, or 100 centimetres cube, at a determinate
temperature, may precipitate exactly one gramme of silver. The solution
may be kept at a constant temperature, and in this case the assay stands
in want of no correction; or if its temperature be variable, the assay
must be corrected according to its influence. These two circumstances
make no change in the principle of the process, but they are
sufficiently important to occasion some modifications in the apparatus.
Experience has decided the preference in favour of applying a correction
to a variable temperature.

We readily obtain a volume of 100 cubic centimetres by means of a
_pipette_, _fig._ 83., so gauged that when filled with water up to the
mark _a_, _b_, and well dried at its point, it will run out, at a
continuous efflux, 100 grammes of water at the temperature of 15 C. (59
Fah.). We say purposely at one efflux, because after the cessation of
the jet, the pipette may still furnish two or three drops of liquid,
which must not be counted or reckoned upon. The weight of the volume of
the normal solution, taken in this manner with suitable precautions,
will be uniform from one extreme to another, upon two centimetres and a
half, at most, or to a quarter of a thousandth, and the difference from
the mean will be obviously twice less, or one half. Let us indicate the
most simple manner of taking a measure of the normal solution of sea
salt.

[Illustration: 83 84]

After having immersed the beak _c_ of the pipette in the solution, we
apply suction by the mouth, to the upper orifice, and thereby raise the
liquid to _d_ above the circular line _a b_. We next apply neatly the
forefinger of one hand to this orifice, remove the pipette from the
liquid, and seize it as represented in _fig._ 84. The mark _a b_ being
placed at the level of the eye, we make the surface of the solution
become exactly a tangent to the plane _a b_. At the instant it becomes a
tangent, we leave the beak _c_ of the pipette open, by taking away the
finger that had been applied to it, and without changing any thing else
in the position of the hands, we empty it into the bottle which should
receive the solution, taking care to remove it whenever the efflux has
run out.

If after filling the pipette by suction, any one should find a
difficulty in applying the forefinger fast enough to the upper orifice,
without letting the liquid run down below the mark _a b_, he should
remove the pipette from the solution with its top still closed with his
tongue, then apply the middle finger of one of his hands to the lower
orifice; after which he may withdraw his tongue, and apply the
forefinger of the other hand to the orifice previously wiped. This mode
of obtaining a measure of normal solution of sea salt is very simple,
and requires no complex apparatus; but we shall indicate another
manipulation still easier, and also more exact.

In this new process the pipette is filled from the top like a bottle,
instead of being filled by suction, and it is moreover fixed. _Fig._ 85.
represents the apparatus. D and D´ are two sockets separated by a stop
cock R. The upper one, tapped interiorly, receives, by means of a cork
stopper L, the tube T, which admits the solution of sea salt. The lower
socket is cemented on to the _pipette_; it bears a small air-cock R´,
and a screw plug V, which regulates a minute opening intended to let the
air enter very slowly into the pipette. Below the stop-cock R´, a silver
tube N, of narrow diameter, soldered to the socket, leads the solution
into the _pipette_, by allowing the air, which it displaces, to escape
by the stop-cock R´. The screw plug, with the milled head V´, replaces
the ordinary screw by which the key of the stop-cock may be made to
press, with more or less force, upon its conical seat.

[Illustration: 85 86]

_Fig._ 86. represents, in a side view, the apparatus just described. We
here remark an air-cock R, and an opening _m_. At the extremity Q of the
same figure, the conical pipe T enters, with friction. It is by this
pipe that the air is sucked into the pipette, when it is to be filled
from its beak.

[Illustration: 87]

The _pipette_ is supported by two horizontal arms H K (_fig._ 87.)
moveable about a common axis A A, and capable of being drawn out or
shortened by the aid of two longitudinal slits. They are fixed steadily
by two screw nuts _e e´_, and their distance may be varied by means of
round bits of wood or cork interposed, or even by opposite screw nuts _o
o´_. The upper arm H is pierced with a hole, in which is fixed, by the
pressure of a wooden screw _v_, the socket of the _pipette_. The
corresponding hole of the lower arm is larger; and the beak of the
_pipette_ is supported in it by a cork stopper L. The apparatus is fixed
by its tail-piece P, by means of a screw to the corner of a wall, or any
other prop.

The manner of filling the pipette is very simple. We begin by applying
the fore-finger of the left hand to the lower aperture _c_; we then open
the two stop-cocks R and R´. Whenever the liquor approaches the neck of
the _pipette_, we must temper its influx, and when it has arrived at
some millimetres above the mark _a b_, we close the two stop-cocks, and
remove our forefinger. We have now nothing more to do than to regulate
the _pipette_; for which purpose the liquid must touch the line _a b_,
and must simply adhere externally to the beak of the _pipette_.

[Illustration: 88]

This last circumstance is easily adjusted. After taking away the finger
which closed the aperture _c_ of the _pipette_, we apply to this orifice
a moist sponge _m_, _fig._ 88., wrapped up in a linen rag, to absorb the
superfluous liquor as it drops out. This sponge is called the
handkerchief (_mouchoir_), by M. Gay Lussac. The _pipette_ is said to be
wiped when there is no liquor adhering to its point exteriorly.

For the convenience of operating, the handkerchief is fixed by friction
in a tube of tin plate, terminated by a cup, open at bottom to let the
droppings flow off into the cistern C, to which the tube is soldered. It
may be easily removed for the purpose of washing it; and, if necessary,
a little wedge of wood, _o_, can raise it towards the _pipette_.

To complete the adjustment of the _pipette_, the liquid must be made
merely to descend to the mark _a_, _b_. With this view, and whilst the
handkerchief is applied to the beak of the _pipette_, the air must be
allowed to enter very slowly by unscrewing the plug V, _fig._ 85.; and
at the moment of the contact the handkerchief must be removed, and the
bottle F, destined to receive the solution, must be placed below the
orifice of the _pipette_, _fig._ 88. As the motion must be made rapidly,
and without hesitation, the bottle is placed in a cylinder of tin-plate,
of a diameter somewhat greater, and forming one body with the cistern
and the handkerchief. The whole of this apparatus has for a basis a
plate of tinned iron, moveable between two wooden rulers R R, one of
which bears a groove, under which the edge of the plate slips. Its
traverses are fixed by two abutments _b b_, placed so that when it is
stopped by one of them, the beak of the _pipette_ corresponds to the
centre of the neck of the bottle, or is a tangent to the handkerchief.
This arrangement, very convenient for wiping the _pipette_ and emptying
it, gives the apparatus sufficient solidity, and allows of its being
taken away, and replaced without deranging any thing. It is obvious that
it is of advantage, when once the entry of the air into the _pipette_
has been regulated by the screw V, to leave it constantly open, because
the motion from the handkerchief to the bottle is performed with
sufficient rapidity to prevent a drop of the solution from collecting
and falling down.

[Illustration: 89]

_Temperature of the Solution._--After having described the manner of
measuring by volume the normal solution of the sea salt, we shall
indicate the most convenient means of taking the temperature. The
thermometer is placed in a tube of glass T, _fig._ 89., which the
solution traverses to arrive at the _pipette_. It is suspended in it by
a piece of cork, grooved on the four sides to afford passage to the
liquid. The scale is engraved upon the tube itself, and is repeated at
the opposite side, to fix the eye by the coincidence of this double
division at the level of the thermometric column. The tube is joined
below to another narrower one, through which it is attached by means of
a cork stopper B, in the socket of the stop-cock of the _pipette_. At
its upper part it is cemented into a brass socket, screw-tapped in the
inside, which is connected in its turn by a cock, with the extremity,
also tapped, of the tube above T, belonging to the reservoir of the
normal solution. The corks employed here as connecting links between the
parts of the apparatus, give them a certain flexibility, and allow of
their being dismounted and remounted in a very short time; but it is
indispensable to make them be traversed by a hollow tube of glass or
metal, which will hinder them from being crushed by the pressure they
are exposed to. If the precaution be taken to grease them with a little
suet and to fill their pores, they will suffer no leakage.

_Preservation of the Normal Solution of Sea Salt in metallic
Vessels._--M. Gay Lussac uses for this purpose a cylindrical vessel or
drum of copper, of a capacity of about 110 litres, having its inside
covered with a rosin and wax cement.

_Preparation of the Normal Solution of Sea Salt, measuring it by
Volume._--If the drum contains 110 litres, we should put only 105 into
it, in order that sufficient space may be left for agitating the liquor
without throwing it out. According to the principle that 100 centimetres
cube, or 1/10 of a litre of the solution should contain enough of sea
salt to precipitate a gramme of pure silver; and, admitting moreover,
13·516 for the prime equivalent of silver, and 7·335 for that of sea
salt, we shall find the quantity of pure salt that should be dissolved
in the 105 litres of water, and which corresponds to 105 × 10 = 1050
grammes of silver, to be by the following proportion:--

  13·516 : 7·335 ∷ 1050 gramm. : x = 569·83 gr.

And as the solution of the sea salt of commerce, formerly mentioned,
contains approximately 250 grammes per kilogramme, we must take 2279·3
grammes of this solution to have 569·83 gram. of salt. The mixture being
perfectly made, the tubes and the _pipette_ must be several times washed
by running the solution through them, and putting it into the drum. The
standard of the solution must be determined after it has been well
agitated, supposing the temperature to remain uniform.

To arrive more conveniently at this result, we begin by preparing two
_decimes_ solutions; one of silver, and another of sea salt.

The decime solution of silver is obtained by dissolving 1 gramme of
silver in nitric acid, and diluting the solution with water till its
volume become a litre.

The decime solution of sea salt may be obtained by dissolving 0·543
grammes of pure sea salt in water, so that the solution shall occupy a
litre; but we shall prepare it even with the normal solution which we
wish to test, by mixing a measure of it with 9 measures of water; it
being understood that this solution is not rigorously equivalent to that
of silver, and that it will become so, only when the normal solution
employed for its preparation shall be finally of the true standard.
Lastly, we prepare beforehand several stoppered phials, in each of which
we dissolve 1 gramme of silver in 8 or 10 grammes of nitric acid. For
brevity’s sake we shall call these tests.

Now to investigate the standard of the normal solution, we must transfer
a _pipette_ of it into one of these test phials; and we must agitate the
liquors briskly to clarify them. After some instants of repose, we must
pour in 2 thousandths of the _decime_ solution of sea salt, which, we
suppose, will produce a precipitate. The normal liquor is consequently
too feeble; and we should expect this, since the sea salt employed was
not perfectly pure. We agitate and add 2 fresh thousandths, which will
also produce a precipitate. We continue thus by successive additions of
2 thousandths, till the last produces no precipitation. Suppose that we
have added 16 thousandths: the last two should not be reckoned, as they
produced no precipitate; the preceding two were necessary, but only in
part; that is to say, the useful thousandths added are above 12 and
below 14, or otherwise they are on an average equal to 13.

Thus, in the condition of the normal solution, we require 1013 parts of
it to precipitate one gramme of silver, while we should require only
1000. We shall find the quantity of concentrated solution of sea salt
that we should add, by noting that the quantity of solution of sea salt,
at first employed, viz. 2279·3 grammes, produced a standard of only 987
thousandths = 1000 - 13; and by using the following proportion:

  987 : 2279·3 ∷ 13 : x = 30·02 grammes.

This quantity of the strong solution of salt, mixed with the normal
solution in the drum, will correct its standard, and we shall now see by
how much.

After having washed the tubes and the _pipette_, with the new solution,
we must repeat the experiment upon a fresh gramme of silver. We shall
find, for example, in proceeding only by a thousandth at a time, that
the first causes a precipitate, but not the second. The standard of the
solution is still too weak, and is comprised between 1000 and 1001; that
is to say, it may be equal to 1000-1/2, but we must make a closer
approximation.

We pour into the test bottle 2 thousandths of the _decime_ solution of
silver, which will destroy, perceptibly, two thousandths of sea salt,
and the operation will have retrograded by two thousandths; that is to
say, it will be brought back to the point at which it was first of all.
If, after having cleared up the liquor, we add half a thousandth of the
decime solution, there will necessarily be a precipitate, as we knew
beforehand, but a second will cause no turbidity. The standard of the
normal liquor will be consequently comprehended between 1000 and
1000-1/2, or equal to 1000-1/4.

We should rest content with this standard, but if we wish to correct it,
we may remark that the two quantities of solution of salt added, viz.
2279·3 gr. + 30·02 gr. = 2309·32 gr. have produced only 999·75
thousandths, and that we must add a new quantity of it corresponding to
1/4 of a thousandth. We make, therefore, the proportion

  999·75 : 2309·32 ∷ 0·25 : x.

But since the first term differs very little from 1000, we may content
ourselves to have x by taking the 0·25/1000 of 2309·32, and we shall
find 0·577 gr. for the quantity of solution of sea salt to be added to
the normal solution.

It is not convenient to take exactly so small a quantity of solution of
sea salt by the balance, but we shall succeed easily by the following
process. We weigh 50 grammes of this solution, and we dilute it with
water; so that it occupies exactly half a litre, or 500 centimetres
cube. A _pipette_ of this solution, one centimetre cube in volume, will
give a decigramme of the primitive solution, and as such a small
_pipette_ is divided into twenty drops, each drop, for example, will
represent 5 milligrammes of the solution. We should arrive at quantities
smaller still by diluting the solution with a proper quantity of water;
but greater precision would be entirely needless.

The testing of the normal liquor just described, is, in reality, less
tedious than might be supposed. It deserves also to be remarked, that
liquor has been prepared for more than 1000 assays; and that, in
preparing a fresh quantity, we shall obtain directly its true standard,
or nearly so, if we bear in mind the quantities of water and solution of
salt which had been employed.

_Correction of the Standard of the Normal Solution of Sea Salt, when the
Temperature changes._--We have supposed, in determining the standard of
the normal solution of sea salt, that the temperature remained uniform.
The assays made in such circumstances, have no need of correction; but
if the temperature should change, the same measure of the solution will
not contain the same quantity of sea salt. Supposing that we have tested
the solution of the salt at the temperature of 15° C.; if, at the time
of making the experiment, the temperature is 18° C., for example, the
solution will be too weak on account of its expansion, and the _pipette_
will contain less of it by weight; if, on the contrary, the temperature
has fallen to 12°, the solution will be thereby concentrated and will
prove too strong. It is therefore proper to determine the correction
necessary to be made, for any variation of temperature.

To ascertain this point, the temperature of the solution of sea salt was
made successively to be 0°, 5°, 10°, 15°, 20°, 25°, and 30° C.; and
three _pipettes_ of the solution were weighed exactly at each of these
temperatures. The third of these weighings gave the mean weight of a
_pipette_. The corresponding weights of a _pipette_ of the solution,
were afterwards graphically interpolated from degree to degree. These
weights form the second column of the following table, intitled, _Table
of Correction for the Variations in the Temperature of the Normal
Solution of the Sea Salt_. They enable us to correct any temperature
between 0 and 30 degrees centigrade (32° and 86° Fahr.) when the
solution of sea salt has been prepared in the same limits.

Let us suppose, for example, that the solution has been made standard at
15°, and that at the time of using it, the temperature has become 18°.
We see by the second column of the table, that the weight of a measure
of the solution is 100·099 gr. at 15°, and 100·065 at 18°; the
difference 0·034 gr., is the quantity of solution less which has been
really taken; and of course we must add it to the normal measure, in
order to make it equal to one thousand _millièmes_. If the temperature
of the solution had fallen to 10 degrees, the difference of the weight
of a measure from 10 to 15 degrees would be 0·019 gr. which we must on
the contrary deduct from the measure, since it had been taken too large.
These differences of weight of a measure of solution at 15°, from that
of a measure at any other temperature, form the column 15° of the
table, where they are expressed in thousandths; they are inscribed on
the same horizontal lines as the temperatures to which each of them
relates with the sign + _plus_, when they must be added, and with the
sign - _minus_, when they must be subtracted. The columns 5°, 10°, 20°,
25°, 35°, have been calculated in the same manner for the cases in which
the normal solution may have been graduated to each of these
temperatures. Thus, to calculate the column 10, the number 100·118 has
been taken of the column of weights for a term of departure, and its
difference from all the numbers of the same column has been sought.

Table of Correction for the Variations in the Temperature of the Normal
Solution of the Sea Salt.

  +-------+-------+-----+-----+-----+-----+-----+-----+
  |Temper-|Weight.|  5° | 10° | 15° | 20° | 25° | 30° |
  |ature. |       |     |     |     |     |     |     |
  +-------+-------+-----+-----+-----+-----+-----+-----+
  |       | gram. |mill.|mill.|mill.|mill.|mill.|mill.|
  |   4   |100,109|  0·0|- 0·1|+ 0·1|+ 0·7|+ 1·7|+ 2·7|
  |   5   |100,113|  0·0|- 0·1|+ 0·1|+ 0·7|+ 1·7|+ 2·8|
  |   6   |100,115|  0·0|  0·0|+ 0·2|+ 0·8|+ 1·7|+ 2·8|
  |   7   |110,118|+ 0·1|  0·0|+ 0·2|+ 0·8|+ 1·7|+ 2·8|
  |   8   |100,120|+ 0·1|  0·0|+ 0·2|+ 0·8|+ 1·8|+ 2·8|
  |   9   |100,120|+ 0·1|  0·0|+ 0·2|+ 0·8|+ 1·8|+ 2·8|
  |  10   |100,118|+ 0·1|  0·0|+ 0·2|+ 0·8|+ 1·7|+ 2·8|
  |  11   |100,116|  0·0|  0·0|+ 0·2|+ 0·8|+ 1·7|+ 2·8|
  |  12   |100,114|  0·0|  0·0|+ 0·2|+ 0·8|+ 1·7|+ 2·8|
  |  13   |100,110|  0·0|- 0·1|+ 0·1|+ 0·7|+ 1·7|+ 2·7|
  |  14   |100,106|- 0·1|- 0·1|+ 0·1|+ 0·7|+ 1·6|+ 2·7|
  |  15   |100,099|- 0·1|- 0·2|- 0·0|+ 0·6|+ 1·6|+ 2·6|
  |  16   |100,090|- 0·2|- 0·3|- 0·1|+ 0·5|+ 1·5|+ 2·5|
  |  17   |100,078|- 0·4|- 0·4|- 0·2|+ 0·4|+ 1·3|+ 2·4|
  |  18   |100,065|- 0·5|- 0·5|- 0·3|+ 0·3|+ 1·2|+ 2·3|
  |  19   |100,053|- 0·6|- 0·7|- 0·5|+ 0·1|+ 1·1|+ 2·2|
  |  20   |100,039|- 0·7|- 0·8|- 0·6|  0·0|+ 1·0|+ 2·0|
  |  21   |100,021|- 0·9|- 1·0|- 0·8|- 0·2|+ 0·8|+ 1·9|
  |  22   |100,001|- 1·1|- 1·2|- 1·0|- 0·4|+ 0·6|+ 1·7|
  |  23   | 99,983|- 1·3|- 1·4|- 1·2|- 0·6|+ 0·4|+ 1·5|
  |  24   | 99,964|- 1·5|- 1·5|- 1·4|- 0·8|+ 0·2|+ 1·3|
  |  25   | 99,944|- 1·7|- 1·7|- 1·6|- 1·0|  0·0|+ 1·1|
  |  26   | 99,924|- 1·9|- 1·9|- 1·8|- 1·2|- 0·2|+ 0·9|
  |  27   | 99,902|- 2·1|- 2·2|- 2·0|- 1·4|- 0·4|+ 0·7|
  |  28   | 99,879|- 2·3|- 2·4|- 2·2|- 1·6|- 0·7|+ 0·4|
  |  29   | 99,858|- 2·6|- 2·6|- 2·4|- 1·8|- 0·9|+ 0·2|
  |  30   | 99,836|- 2·8|- 2·8|- 2·6|- 2·0|- 1·1|  0·0|
  +-------+-------+-----+-----+-----+-----+-----+-----+

Several expedients have been employed to facilitate and abridge the
manipulations. In the first place, the phials for testing or assaying
the specimens of silver should all be of the same height and of the same
diameter. They should be numbered at their top, as well as on their
stoppers, in the order 1, 2, 3, &c. They may be ranged successively in
tens; the stoppers of the same series being placed on a support in their
proper order. Each two phials should, in their turn, be placed in a
japanned tin case (_fig._ 90.) with ten compartments duly numbered.
These compartments are cut out anteriorly to about half their height, to
allow the bottoms of the bottles to be seen. When each phial has
received its portion of alloy, through a wide-beaked funnel, there must
be poured into it about 10 grammes of nitric acid, of specific gravity
1·28, with a _pipette_, containing that quantity; it is then exposed to
the heat of a water bath, in order to facilitate the solution of the
alloy. The water bath is an oblong vessel made of tin plate, intended to
receive the phials. It has a moveable double bottom, pierced with small
holes, for the purpose of preventing the phials being broken, as it
insulates them from the bottom to which the heat is applied. The
solution is rapid; and, since it emits nitrous vapours in abundance, it
ought to be carried on under a chimney.

[Illustration: 90 91]

_The agitator._--_Fig._ 91. gives a sufficiently exact idea of it, and
may dispense with a lengthened description. It has ten cylindrical
compartments, numbered from 1 to 10. The phials, after the solution of
the alloy, are arranged in it in the order of their numbers. The
agitator is then placed within reach of the _pipette_, intended to
measure out the normal solution of sea salt, and a _pipette_ full of
this solution is put into each phial. Each is then closed with its glass
stopper, previously dipped in pure water. They are fixed in the cells of
the agitator by wooden wedges. The agitator is then suspended to a
spring R, and, seizing it with the two hands, the operator gives an
alternating rapid movement, which agitates the solution, and makes it,
in less than a minute, as limpid as water. This movement is promoted by
a spiral spring, B, fixed to the agitator and the ground; but this is
seldom made use of, because it is convenient to be able to transport the
agitator from one place to another. When the agitation is finished, the
wedges are to be taken out, and the phials are placed in order upon a
table furnished with round cells destined to receive them, and to screen
them from too free a light.

When we place the phials upon this table, we must give them a brisk
circular motion, to collect the chloride of silver scattered round their
sides; we must lift out their stoppers, and suspend them in wire rings,
or pincers. We next pour a thousandth of the decime solution into each
phial; and before this operation is terminated, there is formed in the
first phials, when there _should be_ a precipitate, a nebulous stratum,
very well marked, of about a centimetre in thickness.

At the back of the table there is a black board divided into
compartments numbered from 1 to 10, upon each of which we mark, with
chalk, the thousandths of the decime liquor put into the correspondent
phial. The thousandths of sea salt, which indicate an augmentation of
standard, are preceded by the sign +, and the thousandths of nitrate of
silver by the sign -.

When the assays are finished, the liquor of each phial is to be poured
into a large vessel, in which a slight excess of sea salt is kept; and
when it is full, the supernatant clear liquid must be run off with a
syphon.

The chloride of silver may be reduced without any perceptible loss.
After having washed it well, we immerse pieces of iron or zinc into it,
and add sulphuric acid in sufficient quantity to keep up a feeble
disengagement of hydrogen gas. The mass must not be touched. In a few
days the silver is completely reduced. This is easily recognised by the
colour and nature of the product; or by treating a small quantity of it
with water of ammonia, we shall see whether there be any chloride
unreduced; for it will be dissolved by the ammonia, and will afterwards
appear upon saturating the ammonia with an acid. The chlorine remains
associated with the iron or the zinc in a state of solution. The first
washings of the reduced silver must be made with an acidulous water, to
dissolve the oxide of iron which may have been formed, and the other
washings with common water. After decanting the water of the last
washing, we dry the mass, and add a little powdered borax to it. It must
be now fused. The silver being in a bulky powder is to be put in
successive portions into a crucible as it sinks down. The heat should be
at first moderate; but towards the end of the operation it must be
pretty strong to bring into complete fusion the silver and the scoriæ,
and to effect their complete separation. In case it should be supposed
that the whole of the silver had not been reduced by the iron or zinc, a
little carbonate of potash should be added to the borax. The silver may
also be reduced by exposing the chloride to a strong heat, in contact
with chalk and charcoal.

The following remarks by M. Gay Lussac, the author of the above method,
upon the effect of a little mercury in the humid assay, are important:--

It is well known that chloride of silver blackens the more readily as it
is exposed to an intense light, and that even in the diffused light of a
room, it becomes soon sensibly coloured. If it contains four to five
thousandths of mercury, it does not blacken; it remains of a dead white:
with three thousandths of mercury, there is no marked discolouring in
diffused light; with two thousandths it is slight; with one it is much
more marked, but still it is much less intense than with pure chloride.
With half a thousandth of mercury the difference of colour is not
remarkable, and is perceived only in a very moderate light.

But when the quantity of mercury is so small that it cannot be detected
by the difference of colour in the chloride of silver, it may be
rendered quite evident by a very simple process of concentration.
Dissolve one gramme of the silver supposed to contain 1/4 of a
thousandth of mercury, and let only 1/4 of it be precipitated, by adding
only 1/4 of the common salt necessary to precipitate it entirely. In
thus operating, the 1/4 thousandth of mercury is concentrated in a
quantity of chloride of silver four times smaller: it is as if the
silver having been entirely precipitated, four times as much mercury,
equal to two thousandths, had been precipitated with it.

In taking two grammes of silver, and precipitating only 1/4 by common
salt, the precipitate would be, with respect to the chloride of silver,
as if it amounted to four thousandths. By this process, which occupies
only five minutes, because exact weighing is not necessary, 1/10 of a
thousandth of mercury may be detected in silver.

It is not useless to observe, that in making those experiments the most
exact manner of introducing small quantities of mercury into a solution
of silver, is to weigh a minute globule of mercury, and to dissolve it
in nitric acid, diluting the solution so that it may contain as many
cubic centimetres as the globule weighs of centigrammes. Each cubic
centimetre, taken by means of a _pipette_, will contain one milligramme
of mercury.

If the ingot of silver to be assayed is found to contain a greater
quantity of mercury, one thousandth for example, the humid process ought
either to be given up in this case, or to be compared with cupellation.

When the silver contains mercury, the solution from which the mixed
chlorides are precipitated, does not readily become clear.

Silver containing mercury, put into a small crucible and mixed with lamp
black, to prevent the volatilization of the silver, was heated for three
quarters of an hour in a muffle, but the silver increased sensibly in
weight. This process for separating the mercury, therefore, failed. It
is to be observed, that mercury is the only metal which has thus the
power of disturbing the analysis by the humid way.

ASSAYING OF GOLD.--In estimating or expressing the fineness of gold, the
whole mass spoken of is supposed to weigh 24 carats of 12 grains each,
either real, or merely proportional, like the assayer’s weights; and the
pure gold is called fine. Thus, if gold be said to be 23 carats fine, it
is to be understood, that in a mass, weighing 24 carats, the quantity of
pure gold amounts to 23 carats.

In such small work as cannot be assayed by scraping off a part and
cupelling it, the assayers endeavour to ascertain its fineness or
quality by the touch. This is a method of comparing the colour and other
properties, of a minute portion of the metal, with those of small bars,
the composition of which is known. These bars are called touch needles,
and they are rubbed upon a smooth piece of black basaltes or pottery,
which, for this reason, is called the touchstone. Black flint slate will
serve the same purpose. Sets of gold needles may consist of pure gold;
of pure gold, 23-1/2 carats with 1/2 carat of silver; 23 carats of gold
with one carat of silver; 22-1/2 carats of gold with 1-1/2 carat of
silver; and so on, till the silver amounts to four carats; after which
the additions may proceed by whole carats. Other needles may be made in
the same manner, with copper instead of silver; and other sets may have
the addition, consisting either of equal parts of silver and copper, or
of such proportions as the occasions of business require. The
examination by the touch may be advantageously employed previous to
quartation, to indicate the quantity of silver necessary to be added.

In foreign countries, where trinkets and small work are required to be
submitted to the assay of the touch, a variety of needles is necessary;
but they are not much used in England. They afford, however, a degree of
information which is more considerable than might at first be expected.
The attentive assayer compares not only the colour of the stroke made
upon the touchstone by the metal under examination, with that produced
by his needle, but will likewise attend to the sensation of roughness,
dryness, smoothness, or greasiness, which the texture of the rubbed
metal excites, when abraded by the stone. When two strokes perfectly
alike in colour are made upon the stone, he may then wet them with
aquafortis, which will affect them very differently, if they be not
similar compositions; or the stone itself may be made red-hot by the
fire, or by the blowpipe, if thin black pottery be used; in which case
the phenomena of oxidation will differ, according to the nature and
quantity of the alloy. Six principal circumstances appear to affect the
operation of parting; namely, the quantity of acid used in parting, or
in the first boiling; the concentration of this acid; the time employed
in its application; the quantity of acid made use of in the _reprise_,
or second operation; its concentration; and the time during which it is
applied. From experiment it has been shown, that each of these
unfavourable circumstances might easily occasion a loss of from the half
of a thirty-second part of a carat, to two thirty-second parts. The
assayers explain their technical language by observing, that in the
whole mass consisting of twenty-four carats, this thirty-second part
denotes 1-768th part of the mass. It may easily be conceived, therefore,
that if the whole six circumstances were to exist, and be productive of
errors, falling the same way, the loss would be very considerable.

It is therefore indispensably necessary, that one uniform process should
be followed in the assays of gold; and it is a matter of astonishment,
that such an accurate process should not have been prescribed by
government for assayers, in an operation of such great commercial
importance, instead of every one being left to follow his own judgment.
The process recommended in the old French official report is as
follows:--twelve grains of the gold intended to be assayed must be mixed
with thirty grains of fine silver, and cupelled with 108 grains of lead.
The cupellation must be carefully attended to, and all the imperfect
buttons rejected. When the cupellation is ended, the button must be
reduced, by lamination, into a plate of 1-1/2 inches, or rather more, in
length, and four or five lines in breadth. This must be rolled up upon a
quill, and placed in a matrass capable of holding about three ounces of
liquid, when filled up to its narrow part. Two ounces and a half of very
pure aquafortis, of the strength of 20 degrees of Baumé’s areometer,
must then be poured upon it; and the matrass being placed upon hot
ashes, or sand, the acid must be kept gently boiling for a quarter of an
hour: the acid must then be cautiously decanted, and an additional
quantity of 1-1/2 ounces must be poured upon the metal, and slightly
boiled for twelve minutes. This being likewise carefully decanted, the
small spiral piece of metal must be washed with filtered river water, or
distilled water, by filling the matrass with this fluid. The vessel is
then to be reversed, by applying the extremity of its neck against the
bottom of a crucible of fine earth, the internal surface of which is
very smooth. The annealing must now be made, after having separated the
portion of water which had fallen into the crucible; and, lastly, the
annealed gold must be weighed. For the certainty of this operation, two
assays must be made in the same manner, together with a third assay upon
gold of twenty-four carats, or upon gold the fineness of which is
perfectly and generally known.

No conclusion must be drawn from this assay, unless the latter gold
should prove to be of the fineness of twenty-four carats exactly, or of
its known degree of fineness; for, if there be either loss or surplus,
it may be inferred, that the other two assays, having undergone the same
operation, must be subject to the same error. The operation being made
according to this process by several assayers, in circumstances of
importance, such as those which relate to large fabrications, the
fineness of the gold must not be depended upon, nor considered as
accurately known, unless all the assayers have obtained an uniform
result, without communication with each other. This identity must be
considered as referring to the accuracy of half the thirty-second part
of a carat. For, notwithstanding every possible precaution or
uniformity, it very seldom happens that an absolute agreement is
obtained between the different assays of one and the same ingot; because
the ingot itself may differ in its fineness in different parts of its
mass.

The phenomena of the cupellation of gold are the same as of silver, only
the operation is less delicate, for no gold is lost by evaporation or
penetration into the bone-ash, and therefore it bears safely the highest
heat of the assay furnace. The button of gold never vegetates, and need
not therefore be drawn out to the front of the muffle, but may be left
at the further end till the assay is complete. Copper is retained more
strongly by gold than it is by silver; so that with it 16 parts of lead
are requisite to sweat out 1 of copper; or, in general, twice as much
lead must be taken for the copper alloys of gold, as for those of
silver. When the copper is alloyed with very small quantities of gold,
cupellation would afford very uncertain results; we must then have
recourse to liquid analysis.

M. Vauquelin recommends to boil 60 parts of nitric acid at 22° Baumé, on
the spiral slip or cornet of gold and silver alloy, for twenty-five
minutes, and replace the liquid afterwards by acid of 32°, which must be
boiled on it for eight minutes. This process is free from uncertainty
when the assay is performed upon an alloy containing a considerable
quantity of copper. But this is not the case in assaying finer gold; for
then a little silver always remains in the gold. The surcharge which
occurs here is 2 or 3 thousandths; this is too much, and it is an
intolerable error when it becomes greater, which often happens. This
evil may be completely avoided by employing the following process of M.
Chaudet. He takes 0·500 of the fine gold to be assayed; cupels it with
1·500 of silver, and 1·000 of lead; forms, with the button from the
cupel, a riband or strip three inches long, which he rolls into a
cornet. He puts this into a mattrass with acid at 22° B., which he boils
for 3 or 4 minutes. He replaces this by acid of 32° B., and boils for
ten minutes; then decants off, and boils again with acid of 32°, which
must be finally boiled for 8 or 10 minutes.

Gold thus treated is very pure. He washes the cornet, and puts it entire
into a small crucible permeable to water; heats the crucible to dull
redness under the muffle, when the gold assumes the metallic lustre, and
the cornet becomes solid. It is now taken out of the crucible and
weighed.

When the alloy contains platinum, the assay presents greater
difficulties. In general, to separate the platinum from the gold with
accuracy, we must avail ourselves of a peculiar property of platinum;
when alloyed with silver, it becomes soluble in nitric acid. Therefore,
by a proper quartation of the alloy by cupellation, and boiling the
button with nitric acid, we may get a residuum of pure gold. If we were
to treat the button with sulphuric acid, however, we should dissolve
nothing but the silver. The copper is easily removed by cupellation.
Hence, supposing that we have a quaternary compound of copper, silver,
platinum, and gold, we first cupel it, and weigh the button obtained;
the loss denotes the copper. This button, treated by sulphuric acid,
will suffer a loss of weight equal to the amount of silver present. The
residuum, by quartation with silver and boiling with nitric acid, will
part with its platinum, and the gold will remain pure. For more detailed
explanations, see PLATINUM.


ATOMIC WEIGHTS or ATOMS, are the primal quantities in which the
different objects of chemistry, simple or compound, combine with each
other, referred to a common body, taken as unity. Oxygen is assumed by
some philosophers, and hydrogen by others, as the standard of
comparison. Every chemical manufacturer should be thoroughly acquainted
with the combining ratios which are, for the same two substances, not
only definite, but multiple; two great truths, upon which are founded
not merely the _rationale_ of his operations, but also the means of
modifying them to useful purposes. The discussion of the doctrine of
atomic weights, or prime equivalents, belongs to pure chemistry; but
several of its happiest applications are to be found in the processes of
art, as pursued upon the greatest scale. For many instructive examples
of this proposition, the various chemical manufactures may be consulted
in this Dictionary.


ATTAR OF ROSES. See OILS, VOLATILE, and PERFUMERY.


AURUM MUSIVUM. Mosaic gold, a preparation of tin; which see.


AUTOMATIC, a term which I have employed to designate such economic arts
as are carried on by self-acting machinery. The word “manufacture,” in
its etymological sense, means any system, or objects of industry,
executed by the hands; but in the vicissitude of language, it has now
come to signify every extensive product of art which is made by
machinery, with little or no aid of the human hand, so that the most
perfect manufacture is that which dispenses entirely with manual
labour.[4] It is in our modern cotton and flax mills that automatic
operations are displayed to most advantage; for there the elemental
powers have been made to animate millions of complex organs, infusing
into forms of wood, iron, and brass, an intelligent agency. And as the
philosophy of the fine arts, poetry, painting, and music, may be best
studied in their individual master-pieces, so may the philosophy of
manufactures in these its noblest creations.[5]

  [4] Philosophy of Manufactures, p. 1.

  [5] Ibid., p. 2.

The constant aim and effect of these automatic improvements in the arts
are philanthropic, as they tend to relieve the workmen either from
niceties of adjustment, which exhaust his mind and fatigue his eyes, or
from painful repetition of effort, which distort and wear out his frame.
A well arranged power-mill combines the operation of many work-people,
adult and young, in tending with assiduous skill, a system of productive
machines continuously impelled by a central force. How vastly conducive
to the commercial greatness of a nation, and the comforts of mankind,
human industry can become, when no longer proportioned in its results to
muscular effort, which is by its nature fitful and capricious, but when
made to consist in the task of guiding the work of mechanical fingers
and arms regularly impelled, with equal precision and velocity, by some
indefatigable physical agent, is apparent to every visitor of our
cotton, flax, silk, wool, and machine factories. This great era in the
useful arts is mainly due to the genius of Arkwright. Prior to the
introduction of his system, manufactures were every where feeble and
fluctuating in their development; shooting forth luxuriantly for a
season, and again withering almost to the roots like annual plants.
Their perennial growth then began, and attracted capital, in copious
streams, to irrigate the rich domains of industry. When this new career
commenced, about the year 1770, the annual consumption of cotton in
British manufactures was under four millions of pounds’ weight, and that
of the whole of Christendom was probably not more than ten millions.
Last year the consumption in Great Britain and Ireland was about two
hundred and seventy millions of pounds, and that of Europe and the
United States together, four hundred and eighty millions. In our
spacious factory apartments the benignant power of steam summons around
him his myriads of willing menials, and assigns to each the regulated
task, substituting, for painful muscular effort upon their part, the
energies of his own gigantic arm, and demanding, in return, only
attention and dexterity to correct such little aberrations as casually
occur in his workmanship. Under his auspices, and in obedience to
Arkwright’s polity, magnificent edifices, surpassing far in number,
value, usefulness, and ingenuity of construction, the boasted monuments
of Asiatic, Egyptian, and Roman despotism, have, within the short period
of fifty years, risen up in this kingdom, to show to what extent
capital, industry, and science, may augment the resources of a state,
while they meliorate the condition of its citizens. Such is the
automatic system, replete with prodigies in mechanics and political
economy, which promises, in its future growth, to become the great
minister of civilisation to the terraqueous globe, enabling this
country, as its heart, to diffuse, along with its commerce, the
life-blood of knowledge and religion to myriads of people still lying
“in the region and shadow of death.”[6] Of these truths, the present
work affords decisive evidence in almost every page.

  [6] Philosophy of Manufactures, p. 18.


AUTOMATON. In the etymological sense, this word (self-working) signifies
every mechanical construction which, by virtue of a latent intrinsic
force, not obvious to common eyes, can carry on, for some time, certain
movements more or less resembling the results of animal exertion,
without the aid of external impulse. In this respect, all kinds of
clocks and watches, planetariums, common and smoke jacks, with a vast
number of the machines now employed in our cotton, silk, flax, and wool
factories, as well as in our dyeing and calico printing works, may be
denominated automatic. But the term, automaton, is, in common language,
appropriated to that class of mechanical artifices in which the
purposely concealed power is made to imitate the arbitrary or voluntary
motions of living beings. Human figures, of this kind, are sometimes
styled _Androides_, from the Greek term, _like a man_.

Although, from what we have said, clock-work is not properly placed
under the head automaton, it cannot be doubted that the art of making
clocks in its progressive improvement and extension, has given rise to
the production of automata. The most of these, in their interior
structure, as well as in the mode of applying the moving power, have a
distinct analogy with clocks; and these automata are frequently mounted
in connection with watch work. Towards the end of the 13th century,
several tower clocks, such as those at Strasburg, Lubeck, Prague,
Olmutz, had curious mechanisms attached to them. The most careful
historical inquiry proves that automata, properly speaking, are
certainly not older than _wheel_-clocks; and that the more perfect
structures of this kind are subsequent to the general introduction of
_spring_ clocks. Many accounts of ancient automata, such as the flying
doves of Archytas of Tarentum, Regiomontanus’s iron flies, the eagle
which flew towards the emperor Maximilian, in Nurenberg, in the year
1470, were deceptions, or exaggerated statements; for, three such
masterpieces of art would form now, with every aid of our improved
mechanisms, the most difficult of problems. The imitation of flying
creatures is extremely difficult, for several reasons. There is very
little space for the moving power, and the only material possessed of
requisite strength being metal, must have considerable weight. Two
automata, of the celebrated French mechanician, Vaucauson, first
exhibited in the year 1738, have been greatly admired; namely a
flute-player, five and a half feet high, with its cubical pedestal,
which played several airs upon the German flute; and that, not by any
interior tube-work, but through the actual blowing of air into the
flute, the motion of the tongue, and the skilful stopping of the holes
with the fingers; as also a duck, which imitated many motions of a
natural kind in the most extraordinary manner. This artist has had many
imitators, of whom the brothers, Droz of Chaux de Fonds, were the most
distinguished. Several very beautiful clock mechanisms of theirs are
known. One of them with a figure which draws; another playing on the
piano; a third which writes, besides numerous other combined automata.
Frederick Von Knauss completed a writing machine at Vienna, in the year
1760. It is now in the model cabinet of the Polytechnic Institute, and
consists of a globe 2 feet in diameter, containing the mechanism upon
which a figure 7 inches high sits, and writes upon a sheet of paper
fixed to a frame, whatever has been placed beforehand upon a regulating
cylinder. At the end of every line, it rises and moves its hand
sideways, in order to begin a new line.

Very complete automata have not been made of late years, because they
are very expensive; and by soon satisfying curiosity, they cease to
interest. Ingenious mechanicians find themselves better rewarded by
directing their talents to the self-acting machinery of modern
manufactures. We may notice here, however, the mechanical trumpeter of
Mälzl, at Vienna, and a similar work of Kauffmann, at Dresden. In French
Switzerland some artists continue to make minute automata which excite
no little wonder; such as singing canary birds, with various movements
of a natural kind; also little birds, sometimes hardly three quarters of
an inch long, in snuff-boxes and watches of enamelled gold. Certain
artificial figures which have been denominated automata, hardly deserve
the name; since trick and confederacy are more or less concerned in
their operation. To this head belong a number of figures apparently
speaking by mechanism; a clock which begins to strike, or to play, when
a person makes a sign of holding up his finger; this effect being
probably produced by a concealed green-finch, or other little bird,
instructed to set off the _détente_ of the wheel-work at a signal. It is
likely, also, that the chess player of Von Kempelen, which excited so
much wonder in the last century, had a concealed confederate. Likewise,
the very ingenious little figures of Tendler, father and son, which
imitated English horsemen and rope-dancers, constructed at Eisenerz, in
Styria, are probably no more true automata than the _fantoccini_, or
figures of puppets which are exhibited in great perfection in many towns
of Italy, especially at Rome.

The moving power of almost all automata is a wound-up steel spring;
because, in comparison with other means of giving motion, it takes up
the smallest room, is easiest concealed, and set a going. Weights are
seldom employed, and only in a partial way. The employment of other
moving powers is more limited; sometimes fine sand is made to fall on
the circumference of a wheel, by which the rest of the mechanism is
moved. For the same purpose water has been employed; and, when it is
made to fall into an air-chamber, it causes sufficient wind to excite
musical sounds in pipes. In particular cases quicksilver has been used,
as, for example, in the Chinese tumblers, which is only a physical
apparatus to illustrate the doctrine of the centre of gravity.

Figures are frequently constructed for playthings, which move by wheels
hardly visible. An example of this simplest kind of automaton which may
be introduced here, as illustrating the self-acting principles of
manufactures, is shown in the figure.

[Illustration: 92]

_Fig._ 92. exhibits the outlines of an automaton, representing a swan,
with suitably combined movements. The mechanism may be described, for
the sake of clearness of explanation, under distinct heads. The first
relates to the motion of the whole figure. By means of this part it
swims upon the water, in directions changed from time to time without
exterior agency. Another construction gives to the figure the faculty of
bending its neck on several occasions, and, to such an extent, that it
can plunge the bill and a portion of the head under water. Lastly, it is
made to move its head and neck slowly from side to side.

On the barrel of the spring, exterior to the usual ratchet wheel, there
is a main-wheel, marked 1, which works into the pinion of the wheel 2.
The wheel 2 moves a smaller one, shown merely in dotted lines, and on
the long axis of the latter, at either end there is a rudder, or
water-wheel, the paddles of which are denoted by the letter _a_. Both of
these rudder-wheels extend through an oblong opening in the bottom of
the figure down into the water. They turn in the direction of the arrow,
and impart a straight-forwards movement to the swan. The chamber, in
which these wheels revolve, is made water tight, to prevent moisture
being thrown upon the rest of the machinery. By the wheel 4, motion is
conveyed to the fly-pinion 5; the fly itself 6, serves to regulate the
working of the whole apparatus, and it is provided with a stop bar, not
shown in the engraving, to bring it to rest, or set it a-going at
pleasure. Here, as we may imagine, the path pursued is rectilinear, when
the rudder-wheels are made to work in a square direction. An oblique
bar, seen only in section at _b_, movable about its middle point,
carries at each end a web foot _c_, so that the direction of the bar
_b_, and of both feet towards the rudder wheels, determines the form of
the path which the figure will describe. The change of direction of that
oblique bar is effected without other agency. For this purpose, the
wheel 1 takes into the pinion 7, and this carries round the crown-wheel
8, which is fixed, with an eccentric disc 9, upon a common axis. While
the crown-wheel moves in the direction of the arrow, it turns the
smaller eccentric portion of the elliptic disc towards the lever _m_,
which, pressed upon incessantly by its spring, assumes, by degrees, the
position corresponding with the middle line of the figure, and
afterwards an oblique position; then it goes back again, and reaches its
first situation; consequently through the reciprocal turning of the bar
_h_, and the swim-foot, is determined and varied the path which the swan
must pursue. This construction is available with all automata, which
work by wheels; and it is obvious, that we may, by different forms of
the disc 9, modify, at pleasure, the direction and the velocity of the
turnings. If the disc is a circle for instance, then the changes will
take place less suddenly; if the disc has an outward and inward
curvature, upon whose edge the end of the lever presses with a roller,
the movement will take place in a serpentine line.

The neck is the part which requires the most careful workmanship. Its
outward case must be flexible, and the neck itself should therefore be
made of a tube of spiral wire, covered with leather, or with a feathered
bird-skin. The double line in the interior, where we see the triangles
_e e e_, denotes a steel spring made fast to the plate 10, which forms
the bottom of the neck; it stands loose, and needs to be merely so
strong as to keep the neck straight, or to bend it a little backwards.
It should not be equally thick in all points, but it should be weaker
where the first graceful bend is to be made; and, in general, its
stiffness ought to correspond to the curvature of the neck of this bird.
The triangles _e_ are made fast at their base to the front surface of
the spring; in the points of each there is a slit, in the middle of
which a movable roller is set, formed of a smoothly turned steel rod. A
thin catgut string _f_, runs from the upper end of the spring, where it
is fixed over all these rollers, and passes through an aperture pierced
in the middle of 10, into the inside of the rump. If the catgut be drawn
straight back towards _f_, the spring, and consequently the neck, must
obviously be bent, and so much the more, the more tightly _f_ is pulled,
and is shortened in the hollow of the neck. How this is accomplished by
the wheel-work will presently be shown. The wheel 11 receives its motion
from the pinion _s_, connected with the main wheel 1. Upon 11 there is,
moreover, the disc 12, to whose circumference a slender chain is
fastened. When the wheel 11 turns in the direction of the arrow, the
chain will be so much pulled onwards through the corresponding advance
at the point at 12, till this point has come to the place opposite to
its present situation, and, consequently, 11 must have performed half a
revolution. The other end of the chain is hung in the groove of a very
movable roller 14; and this will be turned immediately by the unwinding
of the chain upon its axis. There turns, in connection with it, however,
the large roller 13, to which the catgut _f_ is fastened; and as this is
pulled in the direction of the arrow, the neck will be bent until the
wheel 11 has made a half revolution. Then the drag ceases again to act
upon the chain and the catgut; the spring in the neck comes into play:
it becomes straight, erects the neck of the animal, and turns the
rollers 13 and 14, back into their first position.

The roller 13 is of considerable size, in order that through the slight
motion of the roller 14, a sufficient length of the catgut may be wound
off, and the requisite shortening of the neck may be effected; which
results from the proportion of the diameters of the rollers 11, 13, and
14. This part of the mechanism is attached as near to the side of the
hollow body as possible, to make room for the interior parts, but
particularly for the paddle-wheels. Since the catgut, _f_, must pass
downwards on the middle from 10, it is necessary to incline it sideways
and outwards towards 13, by means of some small rollers.

The head, constituting one piece with the neck, will be depressed by the
complete flexure of this; and the bill, being turned downwards in front
of the breast, will touch the surface of the water. The head will not be
motionless; but it is joined on both sides by a very movable hinge, with
the light ring, which forms the upper part of the clothing of the neck.
A weak spring, _g_, also fastened to the end of the neck, tends to turn
the head backwards; but in the present position it cannot do so, because
a chain at _g_, whose other end is attached to the plate 10, keeps it on
the stretch. On the bending of the neck, this chain becomes slack; the
spring _g_ comes into operation, and throws the head so far back, that,
in its natural position, it will reach the water.

Finally, to render the turning of the head and the neck practicable, the
latter is not closely connected with the rump, while the plate 10 can
turn in a cylindrical manner upon its axis, but cannot become loose
outwardly. Moreover, there is upon the axis of the wheel 1, and behind
it (shown merely as a circle in the engraving) a bevel wheel, which
works into a second similar wheel, 15, so as to turn it in a horizontal
direction. The pin 16, of the last wheel, works upon a two-armed lever
19, movable round the point _h_, and this lever moves the neck by means
of the pin 17. The shorter arm of the lever 19 has an oval aperture in
which the pin 16 stands. As soon as this, in consequence of the movement
of the bevel-wheel 15, comes into the dotted position, it pushes the
oval ring outwards on its smaller diameter, and thereby turns the lever
upon the point _h_, into the oblique direction shown by the dotted
lines. The pin 16, having come on its way right opposite to its present
position, sets the lever again straight. Then the lever, by the further
progress of the pin in its circular path, is directed outwards to the
opposite side; and, at last, when 15 has made an entire revolution, it
is quite straight. The longer arm of the lever follows, of course, these
alternating movements, so that it turns the neck upon its plate 10, by
means of the pin 17; and, as 18 denotes the bill, this comes into the
dotted position. It may be remarked in conclusion, that the drawing of
_fig._ 92. represents about half the size of which the automaton may be
constructed, and that the body may be formed of thin sheet-copper or
brass.

[Illustration: 94 95]

_Fig._ 93, 94, 95. show the plan of a third automaton. A horse which
moves its feet in a natural way, and draws a carriage with two figures
sitting in it. The man appears to drive the horse with a whip; the woman
bends forwards from him in front. The four wheels of the carriage have
no connection with the moving mechanism. In _fig._ 95., some parts are
represented upon a larger scale. The wheel 1, in _fig._ 93. operates
through the two carrier wheels upon the wheels marked 4 and 5. By means
of the axis of these two wheels, the feet are set in motion. The left
fore-foot, _a_, then the right hinder foot, move themselves backwards,
and take hold of the ground with small tacks in their hoofs, while the
two other legs are bent and raised, but no motion of the body takes
place. The carriage, however, with which the horse is connected,
advances upon its wheels. By studying the mechanism of the foot, _a_,
and the parts connected with it, we can readily understand the
principles of the movement. The axis of wheel 4 is crank-shaped, on both
sides, where it has to operate directly on the fore feet; but for each
foot, it is bent in an opposite direction, as is obvious in the front
view _fig._ 94. This crank, or properly its part furthest from the axis,
serves instead of the pin 16, in the swan, and moves like it in an oval
spot, _p_, _fig._ 93. a two-armed lever, which gives motion through
tooth-work, but not as in the swan, by means of a second pin. This
wheel-work renders the motion smoother. The above lever has its fulcrum
at _n_, _fig._ 93., about which it turns alternately, to the one and the
other side, by virtue of the rotation of the wheel 4. The toothed arch,
or the half-wheel on the under side, lays hold of a shorter lever, in a
similar arch, upon the upper joint of the foot, which is moved forwards
and backwards upon the pivot _m_. In virtue of the motions in the
direction of the arrow, the foot _a_ will move itself first obliquely
backwards, without bending, and the body will thereby bend itself
forwards. When the right hind foot makes the same motion, both the other
feet are raised and bent. The joints of the foot at _d_ and _e_ are
formed of hinges, which are so constructed that they can yield no
farther than is necessary at every oblique position of the foot. With
the continued rotation of the wheel 4, the lever turns itself about _n_,
in an inverted direction inwards, and impels the uppermost foot-joint
forwards, so that it forms an acute angle with the body in front. The
foot is now twice bent upon its joints. This takes place by the traction
of the chain _t_, which is led over rollers (as the drawing shows) to
the foot, and is there fastened. As its upper end has its fixed point in
the interior of the body, it is therefore drawn by the eccentric pin _r_
standing in the vicinity of _m_, and thus bends the foot at the hinges.
If there were space for it, a roller would answer better than a pin. By
the recedure of the uppermost joint into the first position, the tension
of the chain _t_ ceases again of itself, while the pin _r_ removes from
it, and the foot is again extended in a straight line by the small
springs operating upon its two under parts, which were previously bent
stiffly by the chain. By the aid of the figures with this explanation,
it will be apparent that all the fore feet have a similar construction,
that the proper succession of motions will be effected through the
toothed arcs, and the position of the cranks on the axis of the wheels 4
and 5, and hence the advance of the figure must follow. The wheel 6 puts
the fly 7 in motion, by means of the small wheel marked 1; on the fixed
points of the 4 chains, by means of a ratchet-wheel and a catch, the
necessary tension will again be produced when the chains have been drawn
out a little. There is sufficient room for a mechanism which could give
motion to the head and ears, were it thought necessary.

The proper cause of the motions may now be explained. In _fig._ 95.,
_a_, is a wheel connected with the wound-up spring, by which the motion
of the two human figures, and also, if desired, that of the horse may be
effected. The axis of the wheel _b_ carries a disc with pins, which
operate upon the two-armed lever with its fulcrum _e_, and thus cause
the bending of the upper part of one of the figures, which has a hinge
at _f_. On the axis of that wheel there is a second disc _c_, for giving
motion to the other figure; which, for the sake of clearness, is shown
separate, although it should sit alongside of its fellow. On the upper
end of the double-armed lever _d_, there is a cord whose other end is
connected with the moving arm, in the situation _i_, and raises it
whenever a pin in the disc presses the under part of the lever. A spring
_h_ brings the arm back into the original position, when a pin has
passed from the lever, and has left it behind. The pins at _c_ and _d_
may be set at different distances from the middle of the disc, whereby
the motions of the figures by every contact of another pin, are varied,
and are therefore not so uniform, and consequently more natural.

For the connexion of both mechanisms, namely, the carriage with the
horse, various arrangements may be adopted. Two separate traction
springs should be employed; one at _a_, _fig._ 95., in the coach-seat;
the other in the body of the horse. In the coach-seat at _b_, the fly
with its pinion, as well as a ratchet-wheel, is necessary. By means of
the shaft, the horse is placed in connexion with the waggon. It may,
however, receive its motion from the spring in the carriage, in which
case one spring will be sufficient. Upon the latter plan the following
construction maybe adopted:--To the axis of _b_, _fig._ 95., a bevel
wheel is to be attached, and from this the motion is to be transmitted
to the bottom of the carriage with the help of a second bevel wheel _s_,
connected with a third bevel wheel _t_. This again turns the wheel _u_,
whose long axis _v_ goes to the middle of the horse’s body, in an
oblique direction, through the hollow shaft. This axis carries an
endless screw 9, _fig._ 93., with very oblique threads, which works into
the little wheel 8, corresponding to the wheel 1, through an opening in
the side of the horse, and in this way sets the mechanism of the horse
a-going. With this construction of _fig._ 95., a spring of considerable
strength is necessary, or if the height of the carriage-seat does not
afford sufficient room, its breadth will answer for placing two weaker
springs alongside of each other upon a common barrel.


AXE. A tool much used by carpenters for cleaving, and roughly
fashioning, blocks of wood. It is a flat iron wedge, with an oblong
steel edge, parallel to which, in the short base, is a hole for
receiving and holding fast the end of a strong wooden handle. In the
cooper’s _adze_, the oblong edge is at right angles to the handle, and
is slightly curved up, or inflected towards it.


AXLES, of carriages; for their latest improvements, see WHEEL CARRIAGES.


AXUNGE. Hog’s lard; see FAT and OILS.


AZOTIZED, said of certain vegetable substances, which, as containing
azote, were supposed at one time to partake, in some measure, of the
animal nature; most animal bodies being characterised by the presence of
much azote in their composition. The vegetable products, indigo,
cafeine, gluten, and many others, contain abundance of azote.


AZURE, the fine blue pigment, commonly called smalt, is a glass coloured
with oxide of cobalt, and ground to an impalpable powder.

The manufacture of azure, or smalt, has been lately improved in Sweden,
by the adoption of the following process:--

The cobalt ore is first roasted till the greater part of the arsenic is
driven off. The residuary impure black oxide is mixed with as much
sulphuric acid (concentrated) as will make it into a paste, which is
exposed at first to a moderate heat, then to a cherry-red ignition for
an hour. The sulphate thus obtained is reduced to powder, and dissolved
in water. To the solution, carbonate of potash is gradually added, in
order to separate the remaining portion of oxide of iron; the quantity
of which depends upon the previous degree of calcination. If it be not
enough oxidized, the iron is difficult to be got rid of.

When, from the colour of the precipitate, we find that the potash
separates merely carbonate of cobalt, it is allowed to settle, the
supernatant liquor is decanted, and precipitated, by means of a solution
of silicate of potash, prepared as follows:--

Ten parts of potash are carefully mixed with fifteen parts of finely
ground flints or sand, and one part of pounded charcoal. This mixture is
melted in a crucible of brick clay, an operation which requires steady
ignition during 5 or 6 hours. The mass, when melted and pulverized, may
be easily dissolved in boiling water, adding to it, by little at a time,
the glass previously ground. The filtered solution is colourless, and
keeps well in the air, if it contains one part of glass for 5 or 6 of
water. The silicate of cobalt, which precipitates upon mixing the two
solutions, is the preparation of cobalt most suitable for painting upon
porcelain, and for the manufacture of blue glass. See COBALT.




B.


BABLAH. The rind or shell which surrounds the fruit of the _mimosa
cineraria_; it comes from the East Indies, as also from Senegal, under
the name of Neb-neb. It contains gallic acid, tannin, a red colouring
matter, and an azotized substance; but the proportion of tannin is
smaller than in sumach, galls, and _knoppern_ (gall-nuts of the common
oak) in reference to that of gallic acid, which is considerable in the
bablah. It has been used, in dyeing cotton, for producing various shades
of drab; as a substitute for the more expensive astringent die-stuffs.


BAGASSE. The sugar-cane, in its dry, crushed state, as delivered from
the sugar-mill. It is much employed for fuel in the colonial
sugar-houses.


BAKING. (_Cuire_, Fr. _Backen_, Germ.) The exposure of any body to such
a heat as will dry and consolidate its parts without wasting them. Thus
wood, pottery, and porcelain, are baked, as well as bread.


BALANCE. To conduct arts, manufactures, and mines, with judgment and
success, recourse must be had, at almost every step, to a balance.
Experience proves that all material bodies, existing upon the surface of
the earth, are constantly solicited by a force which tends to bring them
to its centre, and that they actually fall towards it when they are free
to move. This force is called gravity. Though the bodies be not free,
the effort of gravity is still sensible, and the resultant of all the
actions which it exercises upon their material points, constitutes what
is popularly called their _weight_. These weights are, therefore, forces
which may be compared together, and by means of machines may be made to
correspond or be counterpoised.

To discover whether two weights be equal, we must oppose them to each
other in a machine where they act in a similar manner, and then see if
they maintain an equilibrium; for example, we fulfil this condition if
we suspend them at the two extremities of a lever, supported at its
centre, and whose arms are equal. Such is the general idea of a balance.
The beam of a good balance ought to be a bar of well-tempered steel, of
such form as to secure perfect inflexibility under any load which may be
fitly applied to its extremities. Its arms should be quite equal in
weight and length upon each side of its point of suspension; and this
point should be placed in a vertical line over the centre of gravity;
and the less distant it is from it, the more delicate will be the
balance. Were it placed exactly in that centre, the beam would not
spontaneously recover the horizontal position when it was once removed
from it. To render its indications more readily commensurable, a slender
rod or needle is fixed to it, at right angles, in the line passing
through its centres of gravity and suspension. The point, or rather
edge, of suspension, is made of perfectly hard steel, and turns upon a
bed of the same. For common uses the arms of a balance can be made
sufficiently equal to give satisfactory results; but, for the more
refined purposes of science, that equality should never be presumed nor
trusted to; and, fortunately, exact weighing is quite independent of
that equality. To weigh a body is to determine how many times the weight
of that body contains another species of known weight, as of grains or
pounds, for example. In order to find it out, let us place the
substance, suppose a piece of gold, in the left hand scale of the
balance; counterpoise it with sand or shot in the other, till the index
needle be truly vertical, or stand in the middle of its scale, proving
the beam to be horizontal. Now remove gently the piece of gold, and
substitute in its place standard multiple weights of any graduation,
English or French, till the needle again resumes the vertical position,
or till its oscillations upon either side of the zero point are equal.
These weights will represent precisely the weight of the gold, since
they are placed in the same circumstances precisely with it, and make
the same equilibrium with the weight laid in the other scale.

This method of weighing is obviously independent of the unequal length
as well as the unequal weight of the arms of the beam. For its
perfection two requisites only are indispensable. The first is that the
points of suspension should be rigorously the same in the two
operations; for the power of a given weight to turn the beam being
unequal, according as we place it at different distances from the centre
of suspension, did that point vary in the two consecutive weighings, we
would require to employ, in the second, a different weight from that of
the piece of gold, in order to form an equilibrium with the sand or shot
originally put in the opposite scale; and as there is nothing to
indicate such inequality in the states of the beam, great errors would
result from it. The best mode of securing against such inequality is to
suspend the cords of the scales from sharp-edged rings, upon knife
edges, at the ends of the beam, both made of steel so hard tempered as
to be incapable of indentation. The second condition is, that the
balance should be very sensible, that is, when in equilibrium and
loaded, it may be disturbed, and its needle may oscillate, by the
smallest weight put into either of the scales. This sensibility depends
solely upon the centre or nail of suspension; and it will be the more
perfect the less friction there is between that _knife-edge_ surface and
the plane which supports it. Both should therefore be as hard and highly
polished as possible; and should not be suffered to press against each
other, except at the time of weighing. Every delicate balance of
moderate size, moreover, should be suspended within a glass case, to
protect it from the agitations of the air, and the corroding influence
of the weather. In some balances a ball is placed upon the index or
needle, (whether that index stand above or below the beam,) which may be
made to approach or recede from the beam by a fine-threaded screw, with
the effect of varying the centre of gravity relatively to the point of
suspension, and thereby increasing, at will, either the sensibility, or
the stability of the balance. The greater the length of the arms, the
less distant the centre of gravity is beneath the centre of suspension,
the better polished its central knife-edge of 30°, the lighter the whole
balance, and the less it is loaded; the greater will be its sensibility.
In all cases the arms must be quite inflexible. A balance made by
Ramsden for the Royal Society, is capable of weighing ten pounds, and
turns with one hundredth of a grain, which is the seven-millionth part
of the weight. In pointing out this balance to me one evening, Dr.
Wollaston told me it was so delicate, that Mr. Pond, then astronomer
royal, when making some observations with it, found its indications
affected by his relative position before it, although it was inclosed in
a glass case. When he stood opposite the right arm, that end of the beam
preponderated, in consequence of its becoming expanded by the radiation
of heat from his body; and when he stood opposite the left arm, he made
this preponderate in its turn. It is probable that Mr. Pond had
previously adjusted the centres of gravity and suspension so near to
each other as to give the balance its maximum sensibility, consistent
with stability. Were these centres made to coincide, the beam, when the
weights are equal, would rest in any position, and the addition of the
smallest weight would overset the balance, and place the beam in a
vertical position, from which it would have no tendency to return. The
sensibility in this case would be the greatest possible; but the other
two requisites of level and stability would be entirely lost. The case
would be even worse if the centre of gravity were higher than the centre
of suspension, as the balance when deranged, if free, would make a
revolution of no less than a semi-circle. A balance may be made by a
fraudulent dealer to weigh falsely though its arms be equal, provided
the suspension be as low as the centre of gravity, for he has only to
toss his tea, for instance, forcibly into one scale to cause 15 ounces
of it, or thereby, to counterpoise a pound weight in the other.
Inspectors of weights, &c. are not _au fait_ to this fruitful source of
fraud among hucksters.


BALSAMS. (_Baumes_, Fr. _Balsame_, Germ.) Are native compounds of
ethereal or essential oils, with resin, and frequently benzoic acid.
Most of them have the consistence of honey; but a few are solid, or
become so by keeping. They flow either spontaneously, or by incisions
made from trees and shrubs in tropical climates. They possess peculiar
powerful smells, aromatic hot tastes, but lose their odoriferous
properties by long exposure to the air. They are insoluble in water;
soluble, to a considerable degree, in ether; and completely in alcohol.
When distilled with water, ethereal oil comes over, and resin remains in
the retort.

1. BALSAMS WITH BENZOIC ACID:--

_Balsam of Peru_ is extracted from the _myroxylon peruiferum_, a tree
which grows in Peru, Mexico, &c.; sometimes by incision, and sometimes
by evaporating the decoction of the bark and branches of the tree. The
former kind is very rare, and is imported in the husk of the cocoa nut,
whence it is called balsam _en coque_. It is brown, transparent only in
thin layers, of the consistence of thick turpentine; an agreeable smell,
an acrid and bitter taste; formed of two matters, the one liquid, the
other granular, and somewhat crystalline. In 100 parts, it contains 12
of benzoic acid, 88 of resin, with traces of a volatile oil.

The second sort, the _black_ balsam of Peru, is much more common than
the preceding, translucent, of the consistence of well-boiled syrup,
very deep red-brown colour, an almost intolerably acrid and bitter
taste, and a stronger smell than the other balsam. Stoltze regards it as
formed of 69 parts of a peculiar oil, 20·7 of a resin, little soluble in
alcohol, of 6·4 of benzoic acid, of 0·6 of extractive matter, and 0·9 of
water.

From its high price, balsam of Peru is often adulterated with copaiba,
oil of turpentine, and olive oil. One thousand parts of good balsam,
should, by its benzoic acid, saturate 75 parts of crystallised carbonate
of soda. It is employed as a perfume for pomatums, tinctures, lozenges,
sealing-wax, and for chocolate and _liqueurs_, instead of vanilla, when
this happens to be very dear.

_Liquid amber_, _Storax or Styrax_, flows from the leaves and trunk of
the _liquid amber styraciflua_, a tree which grows in Virginia,
Louisiana, and Mexico. It is brownish ash-grey, of the consistence of
turpentine, dries up readily, smells agreeably, like benzoin, has a
bitterish, sharp, burning taste; is soluble in 4 parts of alcohol, and
contains only 1·4 per cent. of benzoic acid.

Balsam of Tolu flows from the trunk of the _myroxylon toluiferum_, a
tree which grows in South America; it is, when fresh, of the consistence
of turpentine, is brownish-red, dries into a yellowish or reddish
brittle resinous mass, of a smell like benzoin; is soluble in alcohol
and ether; affords, with water, benzoic acid.

_Chinese varnish_ flows from the bark of the _Augia sinensis_; it is a
greenish yellow turpentine-like substance, smells aromatic, tastes
strong and rather astringent, in thin layers dries soon into a smooth
shining lac, and consists of resin, ethereous oil, and benzoic acid. It
is soluble in alcohol and ether; and has been employed, immemorially, in
China, for lacquering and varnishing surfaces, either alone or coloured.

2. BALSAMS WITHOUT BENZOIC ACID:--

_Copaiva balsam_, balsam of copahu or capivi, is obtained from incisions
made in the trunk of the _Copaifera officinalis_, a tree which grows in
Brazil and Cayenne. It is pale yellow, middling liquid, clear
transparent, has a bitter, sharp, hot taste; a penetrating disagreeable
smell; a specific gravity of from 0·950 to 0·996. It dissolves in
absolute alcohol, partially in spirit of wine, forms with alkalis,
crystalline compounds. It consists of 45·59 ethereous oil, 52·75 of a
yellow brittle resin, and 1·66 of a brown viscid resin. The oil contains
no oxygen, has a composition like oil of turpentine, dissolves
caoutchouc (according to Durand), but becomes oxidised in the air, into
a peculiar species of resin. This balsam is used for making paper
transparent, for certain lacquers, and in medicine.

_Mecca balsam, or opobalsam_, is obtained both by incisions of, and by
boiling, the branches and leaves of the _Balsamodendron Gileadense_, a
shrub which grows in Arabia Felix, Lesser Asia and Egypt. When fresh it
is turbid, whitish, becomes, by degrees, transparent; yellow, thickish,
and eventually solid. It smells peculiar, but agreeable; tastes bitter
and spicy; does not dissolve completely in hot spirit of wine, and
contains 10 per cent. of ethereous oil, of the spec. grav. 0·876.

_Japan lac varnish_ flows from incisions in the trunk of the _Rhus
Vernix_ (_Melanorrhea usitata_) which is cultivated in Japan, and grows
wild in North America. The juice becomes black in the air; when
purified, dissolves in very little oil; and, mixed with colouring
matter, it constitutes the celebrated varnish of the Japanese.

For Benzoin and Turpentine, see these articles in their alphabetical
places.


BANDANNA. A style of calico printing, in which white or brightly
coloured spots are produced upon a red or dark ground. It seems to have
been practised from time immemorial in India, by binding up firmly with
thread, those points of the cloth which were to remain white or yellow,
while the rest of the surface was freely subjected to the dyeing
operations.

[Illustration: 96]

The European imitations have now far surpassed, in the beauty and
precision of the design, the oriental patterns; having called into
action the refined resources of mechanical and chemical science. The
general principles of producing bright figures upon dark grounds, are
explained in the article CALICO-PRINTING; but the peculiarities of the
Bandanna printing may be conveniently introduced here. In Brande’s
Journal for July 1823, I described the Bandanna gallery of Messrs.
Monteith at Glasgow, which, when in full action some years ago, might be
reckoned the most magnificent and profitable printing apartment in the
world. The white spots were produced by a solution of chlorine, made to
percolate down through the Turkey red cotton cloth, in certain points,
defined and circumscribed by the pressure of hollow lead types in
plates, in a hydraulic press. _Fig._ 96., is an elevation of one press;
A, the top or entablature; B B, the cheeks or pillars; C, the upper
block for fastening the upper lead perforated pattern to; D, the lower
block to which the fellow pattern is affixed, and which moves up and
down with the piston of the press; E, the piston or ram; F, the sole or
base; G, the water-trough, for the discharged or spotted calico to fall
into; H, the small cistern, for the aqueous chlorine or liquor-meter,
with glass tubes for indicating the height of liquor inside of the
cistern; _e e_, glass stopcocks, for admitting the liquor into that
cistern from the general reservoir; _f f_, stopcocks for admitting water
to wash out the chlorine; _g g_, the pattern lead-plates, with screws
for setting the patterns parallel to each other; _m m_, projecting
angular pieces at each corner, perforated with a half-inch hole to
receive the four guide-pins rising from the lower plate, which serve to
secure accuracy of adjustment between the two faces of the lead pattern
plates; _h h_, two rollers which seize and pull through the discharged
pieces, and deliver them into the water-trough. To the left of D there
is a stopcock for filling the trough with water; _l_, is the waste tube
for chlorine liquor and water of washing. The contrivance for blowing a
stream of air across the cloth, through the pattern tubes, is not
represented in the figure.

Sixteen engines, similar to the above, each possessing the power of
pressing with several hundred tons, are arranged in one line, in
subdivisions of four; the spaces between each subdivision serving as
passages to allow the workmen to go readily from the front to the back
of the presses. Each occupies twenty-five feet, so that the total length
of the apartment is 100 feet.

To each press is attached a pair of patterns in lead, (or plates as they
are called,) the manner of forming which will be described in the
sequel. One of these plates is fixed to the upper block of the press.
This block is so contrived, that it rests upon a kind of universal
joint, which enables this plate to apply more exactly to the under
fellow-plate. The latter sits on the moveable part of the press,
commonly called the sill. When this is forced up, the two patterns close
on each other very nicely, by means of the guide-pins at the corners,
which are fitted with the utmost care.

The power which impels this great hydrostatic range is placed in a
separate apartment, called the machinery room. This machinery consists
of two press cylinders of a peculiar construction, having solid rams
accurately fitted to them. To each of these cylinders, three little
force-pumps, worked by a steam-engine, are connected.

The piston of the large cylinder is eight inches in diameter, and is
loaded with a top-weight of five tons. This piston can be made to rise
about two feet through a leather-stuffing or collar. The other cylinder
has a piston of only one inch in diameter, which is also loaded with a
top-weight of five tons. It is capable, like the other, of being raised
two feet through its collar.

Supposing the pistons to be at their lowest point, four of the six small
force-pumps are put in action by the steam-engine, two of them to raise
the large piston, and two the little one. In a short time, so much water
is injected into the cylinders, that the loaded pistons have arrived at
their highest points. They are now ready for working the hydrostatic
discharge-presses, the water pressure being conveyed from the one
apartment to the other, under ground, through strong copper tubes, of
small calibre.

Two valves are attached to each press, one opening a communication
between the large driving-cylinder and the cylinder of the press, the
other between the small driving-cylinder and the press. The function of
the first is simply to lift the under-block of the press into contact
with the upper-block; that of the second, is to give the requisite
compression to the cloth. A third valve is attached to the press, for
the purpose of discharging the water from its cylinder, when the press
is to be relaxed, in order to remove or draw through the cloth.

From twelve to fourteen pieces of cloth, previously dyed Turkey-red, are
stretched over each other, as parallel as possible, by a particular
machine. These parallel layers are then rolled round a wooden cylinder,
called by the workmen, a drum. This cylinder is now placed in its proper
situation at the back of the press. A portion of the fourteen layers of
cloth, equal to the area of the plates, is next drawn through between
them, by hooks attached to the two corners of the webs. On opening the
valve connected with the eight-inch driving-cylinder, the water enters
the cylinder of the press, and instantly lifts its lower block, so as to
apply the under plate with its cloth, close to the upper one. This valve
is then shut, and the other is opened. The pressure of five tons in the
one inch prime-cylinder, is now brought to bear on the piston of the
press, which is eight inches in diameter. The effective force here will,
therefore, be 5 tons × 8² = 320 tons; the areas of cylinders being to
each other, as the squares of their respective diameters. The cloth is
thus condensed between the leaden pattern-plates, with a pressure of 320
tons, in a couple of seconds;--a splendid example of automatic art.

The next step, is to admit the blanching or discharging liquor, (aqueous
chlorine, obtained by adding sulphuric acid to solution of chloride of
lime,) to the cloth. This liquor is contained in a large cistern, in an
adjoining house, from which it is run at pleasure into small lead
cisterns H attached to the presses; which cisterns have graduated index
tubes, for regulating the quantity of liquor according to the pattern of
discharge. The stopcocks on the pipes and cisterns containing this
liquor, are all made of glass.

From the measure-cistern H, the liquor is allowed to flow into the
hollows in the upper lead-plate, whence it descends on the cloth, and
percolates through it, extracting in its passage the Turkey-red dye. The
liquor is finally conveyed into the waste pipe, from a groove in the
under block. As soon as the chlorine liquor has passed through, water is
admitted in a similar manner, to wash away the chlorine; otherwise, upon
relaxing the pressure, the outline of the figure discharged would become
ragged. The passage of the discharge liquor, as well as of the water
through the cloth, is occasionally aided by a pneumatic apparatus, or
blowing machine; consisting of a large gasometer, from which air
subjected to a moderate pressure, may be allowed to issue, and act in
the direction of the liquid, upon the folds of the cloth. By an
occasional twist of the air stopcock, the workman also can ensure the
equal distribution of the discharging liquor, over the whole excavations
in the upper plate. When the demand for goods is very brisk, the air
apparatus is much employed, as it enables the workman to double his
product.

The time requisite for completing the discharging process in the first
press is sufficient to enable the other three workmen to put the
remaining fifteen presses in play. The discharger proceeds now from
press to press, admits the liquor, the air, and the water; and is
followed at a proper interval by the assistants, who relax the press,
move forwards another square of the cloth, and then restore the
pressure. Whenever the sixteenth press has been liquored, &c., it is
time to open the first press. In this routine, about ten minutes are
employed; that is 224 handkerchiefs (16 × 14) are discharged every ten
minutes. The whole cloth is drawn successively forward, to be
successively treated in the above method.

When the cloth escapes from the press, it is passed between the two
rollers in front; from which it falls into a trough of water placed
below. It is finally carried off to the washing and bleaching
department, where the lustre of both the white and the red is
considerably brightened.

By the above arrangement of presses, 1600 pieces, consisting of 12 yards
each = 19,200 yards, are converted into Bandannas in the space of ten
hours, by the labour of four workmen.

The patterns, or plates, which are put into the presses to determine the
white figures on the cloth, are made of lead in the following way. A
trellis frame of cast-iron, one inch thick, with turned-up edges,
forming a trough rather larger than the intended lead pattern, is used
as the solid ground-work. Into this trough, a lead plate about one half
inch thick, is firmly fixed by screw nails passing up from below. To the
edges of this lead plate, the borders of the piece of sheet-lead are
soldered, which covers the whole outer surface of the iron frame. Thus a
strong trough is formed, one inch deep. The upright border gives at once
great strength to the plate, and serves to confine the liquor. A thin
sheet of lead is now laid on the thick lead-plate, in the manner of a
veneer on toilette-tables, and is soldered to it round the edges. Both
sheets must be made very smooth beforehand, by hammering them on a
smooth stone table, and then finishing with a plane: the surface of the
thin sheet (now attached), is to be covered with drawing paper, pasted
on, and upon this the pattern is drawn. It is now ready for the cutter.
The first thing which he does, is to fix down with brass pins all the
parts of the pattern which are to be left solid. He now proceeds with
the little tools generally used by block-cutters, which are fitted to
the different curvatures of the pattern, and he cuts perpendicularly
quite through the thin sheet. The pieces thus detached are easily lifted
out; and thus the channels are formed which design the white figures on
the red cloth. At the bottom of the channels, a sufficient number of
small perforations are made through the thicker sheet of lead, so that
the discharging liquor may have free ingress and egress. Thus, one plate
is finished; from which, an impression is to be taken by means of
printers’ ink, on the paper pasted upon another plate. The impression is
taken in the hydrostatic press. Each pair of plates constitutes a set,
which may be put into the presses, and removed at pleasure.


BARBERRY. The root of this plant contains a yellow colouring matter,
which is soluble in water and alcohol, and is rendered brown by alkalis.
The solution is employed in the manufacture of Morocco leather.


BARILLA. A crude soda, procured by the incineration of the _salsola
soda_, a plant cultivated for this purpose in Spain, Sicily, Sardinia,
&c. Good barilla usually contains, according to my analysis, 20 per
cent. of real alkali, associated with muriates and sulphates, chiefly of
soda, some lime, and alumina, with very little sulphur. Caustic lyes
made from it, are used in the finishing process of the hard soap
manufacture. 125,068 cwts. were imported in 1835, of which only 5,807
were exported. The duty is 2_s._ per cwt. Of the above quantity, 64,174
came from Spain and the Balearic islands, 39,943 from the Canaries, and
20,432 from Italy and the Italian islands.


BARIUM, the metallic basis of Baryta.


BARK OF OAK, for tanning. Unfortunately, the Tables of Revenue published
by the Board of Trade, mix up this bark and the dyeing barks together,
and give the sum of the whole for 1835, at 826,566 cwts., of which only
2,264 were re-exported. The duty is 1_d._ per cwt. from British
possessions, and 8_d._ from other parts.


BARLEY (_Orge_, Fr. _Gerste_, Germ.) English barley is that with
two-rowed ears, or the _hordeum vulgare distichon_ of the botanists; the
Scotch beer or bigg, is the _hordeum vulgare hexastichon_. The latter
has two rows of ears, but 3 corns come from the same point, so that it
seems to be six-eared. The grains of bigg are smaller than those of
barley, and the husks thinner. The specific gravity of English barley
varies from 1·25 to 1·33; of bigg from 1·227 to 1·265; the weight of the
husk of barley is 1/6, that of bigg 2/9. 1000 parts of barley flour
contain, according to Einhof, 720 of starch, 56 sugar, 50 mucilage, 36·6
gluten, 12·3 vegetable albumen, 100 water, 2·5 phosphate of lime, 68
fibrous or ligneous matter. Sp. gravity of barley, is 1·235 by my
trials.


BARM. The yeasty top of fermenting beer. See BEER, DISTILLATION,
FERMENTATION.


BARYTA or BARYTES, one of the simple earths. It may be obtained most
easily by dissolving the native carbonate of barytes (Witherite) in
nitric acid, evaporating the neutral nitrate till crystals be formed,
draining and then calcining these in a covered platina crucible, at a
bright red heat. A less pure baryta may be obtained by igniting strongly
a mixture of the carbonate and charcoal, both in fine powder and
moistened. It is a grayish white earthy looking substance, fusible only
at the jet of the oxy-hydrogen blowpipe, has a sharp caustic taste,
corrodes the tongue and all animal matter, is poisonous even in small
quantities, has a very powerful alkaline reaction; a specific gravity of
4·0; becomes hot, and slakes violently when sprinkled with water,
falling into a fine white powder, called the hydrate of baryta, which
contains 10-1/2 per cent. of water, and dissolves in 10 parts of boiling
water. This solution lets fall abundant columnar crystals of hydrate of
baryta as it cools; but it still retains one twentieth its weight of
baryta, and is called baryta water. The above crystals contain 61 per
cent. of water, of which, by drying, they lose 50 parts. This hydrate
may be fused at a red heat without losing any more water. Of all the
bases, baryta has the strongest affinity for sulphuric acid, and is
hence employed either in the state of the above water, or in that of one
of its neutral salts, as the nitrate or muriate, to detect the presence,
and determine the quantity of that acid present in any soluble compound.
Its prime equivalent, according to Berzelius, is 956,880, oxygen being
100; or 76,676, hydrogen being 1,000. Native sulphate of baryta, or
heavy spar, is fraudulently used to adulterate white lead by the English
dealers to a shameful extent.


BASSORINE. A constituent part of a species of gum which comes from
Bassora, as also of gum tragacanth, and of some gum resins. It is
semi-transparent, difficult to pulverise, swells considerably in cold or
boiling water, and forms a thick mucilage without dissolving. Treated
with ten times its weight of nitric acid, it affords nearly 23 per cent.
of its weight of mucic acid, being much more than is obtainable from gum
arabic or cherry-tree gum. Bassorine is very soluble in water slightly
acidulated with nitric or muriatic acid. This principle is procured by
soaking gum Bassora in a great quantity of cold water, and in removing,
by a filter, all the soluble parts.


BATHS. (_Bains_, Fr. _Baden_, Germ.) Warm baths have lately come into
very general use, and they are justly considered as indispensably
necessary in all modern houses of any magnitude, as also in club-houses,
hotels, and hospitals. But the mode of constructing these baths, and of
obtaining the necessary supplies of hot and cold water, does not appear
to have undergone an improvement equal to the extension of their
employment.

The several points in regard to warm baths, are,

  1. The materials of which they are constructed.
  2. Their situation.
  3. The supply of cold water.
  4. The supply of hot water.
  5. Minor comforts and conveniences.

1. As to the materials of which they are constructed.--Of these the best
are slabs of polished marble, properly bedded with good water-tight
cement, in a seasoned wooden case, and neatly and carefully united at
their respective edges. These, when originally well constructed, form a
durable, pleasant, and agreeable-looking bath; but the expense is often
objectionable, and, in upper chambers, the weight may prove
inconvenient. If of white or veined marble, they are also apt to get
yellow or discoloured by frequent use, and cannot easily be cleansed; so
that large Dutch tiles, as they are called, or square pieces of white
earthenware, are sometimes substituted; which, however, are difficultly
kept water-tight; so that, upon the whole, marble is preferable.

Where there are reasons for excluding marble, copper or tinned iron
plate is the usual material resorted to. The former is most expensive in
the outfit, but far more durable than the latter, which is, moreover,
liable to leakage at the joints, unless most carefully made. Either the
one or the other should be well covered outside and inside, with several
coats of paint, which may then be marbled, or otherwise ornamented.

Wooden tubs, square or oblong, and oval, are sometimes used for warm
baths; and are cheap and convenient, but neither elegant nor cleanly.
The wood always contracts a mouldy smell; and the difficulty and
nuisance of keeping them water-tight, and preventing shrinkage, are such
as to exclude them from all except extemporaneous application.

2. As to the situation of the bath, or the part of the house in which it
is to be placed.--In hotels, and club-houses, this is a question easily
determined: several baths are usually here required, and each should
have annexed to it, a properly warmed dressing-room. Whether they are up
stairs or down stairs, is a question of convenience, but the basement
story, in which they are sometimes placed, should always be avoided;
there is a coldness and dampness belonging to it, in almost all
weathers, which is neither agreeable nor salubrious.

In hospitals, there should be at least two or three baths on each side
of the house, (the men’s and women’s), and the supply of hot water
should be ready at a moment’s notice. The rooms in which the baths are
placed should be light and comparatively large and airy; and such
conveniences for getting into and out of the bath should be adopted, as
the sick are well known to require. The dimensions of these baths should
also be larger than usual.

In private houses, the fittest places for warm baths are dressing-rooms
annexed to the principal bed-rooms; or, where such convenience cannot be
obtained, a separate bath-room, connected with the dressing-room, and
always upon the bed-room floor. All newly-built houses should be
properly arranged for this purpose, and due attention should be paid to
the warming of the bath-room, which ought also to be properly
ventilated. A temperature of 70° may be easily kept up in it, and
sufficient ventilation is absolutely requisite, to prevent the
deposition of moisture upon the walls and furniture.

The objection which formerly prevailed, in respect to the difficulty of
obtaining adequate supplies of water, in the upper rooms, has been
entirely obviated, by having cisterns at or near the top of the house;
and we would just hint that these should be so contrived, as to be
placed out of the reach of frost; a provision of the utmost importance
in every point of view, and very easily effected in a newly-built house,
though it unfortunately happens, that architects usually regard these
matters as trifles, and treat them with neglect, as indeed they do the
warming and ventilation of buildings generally.

3. The supply of water of proper quality and quantity, is a very
important point, as connected with the present subject. The water should
be soft, clean, and pure; and as free as possible from all substances
mechanically suspended in it. In many cases, it answers to dig a well
for the exclusive supply of a large house with water. In most parts of
London this may effectually be accomplished, at a comparatively moderate
expense; and, if the well be deep enough, the water will be abundant,
soft, and pellucid. The labour of forcing it by a pump to the top of the
house, is the only drawback; this, however, is very easily done by a
horse-engine, or there are people enough about town, glad to undertake
it at a shilling a day. I am led to these remarks by observing the
filthy state of the water usually supplied, at very extravagant rates,
by the water companies. It often partakes more of the appearance of
pea-soup than of the pure element; fills our cisterns and pipes with mud
and dirt, and, even when cleared by subsidence, is extremely
unpalatable. It deposits its nastiness in the pipes connected with warm
baths, and throws down a slippery deposit upon the bottom of the vessel
itself to such an extent, as often to preclude its being used, at least
as a luxury, which a clear and clean bath really is. This inconvenience
may, in some measure, be avoided, by suffering the water to throw down
its extraneous matters upon the bottom of the cistern, and drawing our
supplies from pipes a little above it; there will, however, always be
more or less deposit in the pipes themselves; and every time the water
runs into the cistern, the grouts are stirred up, and diffused through
its mass: this, from some cause or other, has lately become an
intolerable nuisance; and he who reflects upon the miscellaneous
contents of Thames water, will not have his appetite sharpened by a
draught of the Grand Junction beverage, nor feel reanimated and
refreshed by bathing in a compound so heterogeneous and unsavoury.

4. and 5. In public bathing establishments, where numerous and constant
baths are required, the simplest and most effective means of obtaining
hot water for their supply consists in drawing it directly into the
baths from a large boiler, placed somewhere above their level. This
boiler should be supplied with proper feeding-pipes and gauges; and,
above all things, its dimensions should be ample; it should be of
wrought iron or copper, except where sea water is used, in which case
the latter metal is sometimes objectionable. The hot water should enter
the bath by a pipe at least an inch and a half in diameter; and the cold
water by one of the same dimension, or somewhat larger, so that the bath
may not be long in filling. The relative proportions of the hot and cold
water are, of course, to be adjusted by a thermometer, and every bath
should have a two-inch waste-pipe, opening about two inches from the top
of the bath, and suffering the excess of water freely to run off; so
that when a person is immersed in the bath, or when the supplies of
water are accidentally left open, there may be no danger of an overflow.

Where there is a laundry in the upper story of the house, or other
convenient place for erecting a copper and its appurtenances, a plan
similar to the above may often be conveniently adopted in private
houses, for the supply of a bath upon the principal bed-room floor. An
attempt is sometimes made to place boilers behind the fires of
dressing-rooms, or otherwise to erect them in the room itself, for the
purpose of supplying warm water; but this plan is always objectionable,
from the complexity of the means by which the supply of water is
furnished to the boiler, and often dangerous from the flues becoming
choaked with soot, and taking fire. Steam is also apt, in such cases, to
escape in quantities into the room; so that it becomes necessary to
search for other methods of heating the bath; one or two of the least
objectionable of which I shall describe.

1. A contrivance of some ingenuity consists in suffering the water for
the supply of the bath to flow from a cistern above it, through a leaden
pipe of about one inch diameter, which is conducted into the kitchen or
other convenient place where a large boiler for the supply of hot water
is required. The bath-pipe is immersed in this boiler, in which it makes
many convolutions, and, again emerging, ascends to the bath. The
operation is simply this:--the cold water passing through the
convolutions of that part of the pipe which is immersed in the boiling
water, receives there sufficient heat for the purpose required, and is
delivered in that state by the ascending pipe into the bath, which is
also supplied with cold water and waste-pipes as usual. The pipe may be
of lead, as far as the descending and ascending parts are concerned, but
the portion forming the worm, or convolutions immersed in the boiler
should be copper, in order that the water within it may receive heat
without impediment.

This plan is economical only where a large boiler is constantly kept at
work in the lower part of the house; otherwise, the trouble and expense
of heating such a boiler, for the mere purpose of the bath, render it
unavailable. The worm-pipe is also apt to become furred, upon the
outside, by the deposition of the earthy impurities of the water in
which it is immersed; it then becomes a bad conductor of heat, is
cleansed with difficulty, and the plan is rendered ineffective. This
system, however, has been adopted, in some particular cases, with
satisfaction.

2. A much more simple, economical, and independent mode of heating a
warm bath, by a fire placed at a distance from it, is the following,
which is found to answer perfectly in private houses, as well as upon a
more extended scale in large establishments. It is certainly open to
some objections, but these are overbalanced by its advantages. A
waggon-shaped boiler, holding about six gallons of water, is properly
placed over a small furnace, in any convenient and safe part of the
house, as the kitchen, scullery, servants’ hall, or wash-house. The bath
itself, of the usual dimensions and construction, is placed where it is
wanted, with a due supply of cold water from above. Two pipes issue from
within an inch of the bottom of the bath at its opposite extremities;
one at the head of the bath, about one inch, and the other at the foot,
an inch and one eighth in diameter. These tubes descend to the boiler,
the smaller one entering it at the bottom, and the larger one issuing
from its top.

Under these circumstances, supposing the pipes and boiler every where
perfectly tight, when the bath is filled, the water will descend into
and expel the air from the boiler, and completely fill it. Now, upon
making a gentle fire under the boiler, an ascending current of warm
water will necessarily pass upwards through the larger pipe which issues
from its top, and cold water will descend by the pipe which enters at
the bottom; and thus, by the establishment of currents, the whole mass
of water in the bath will become heated to the desired point; or, if
above it, the temperature may easily be lowered by the admixture of cold
water.

The advantages of this form of bath are numerous. The shorter the pipes
of communication the better, but they may extend forty or fifty feet
without any inconvenience beyond that of expense; so that there is no
obstacle to the bath being near the bed-room while the boiler is on the
basement story. There is but little time required for heating the bath;
the water in which may, if requisite, be raised to about 100° in about
half an hour from the time of lighting the fire. The consumption of fuel
is also trifling.

The following are the chief disadvantages attendant upon this plan, and
the means of obviating them:--

It is necessary, when the water has acquired its proper temperature, to
withdraw the fire from the boiler, or not to use the bath immediately,
as it may go on acquiring some heat from the boiler, so that we may
become inconveniently hot in the bath. When, therefore, this bath is
used, we may proceed as follows:--heat the water in it an hour before it
is wanted, to about 100°, and then extinguish the fire. The water will
retain its temperature, or nearly so, for three or four hours,
especially if the bath be shut up with a cover; so that when about to
use it, cold water may be admitted till the temperature is lowered to
the required point, and thus all the above inconveniences are avoided.

Another disadvantage of this bath arises from too fierce a fire being
made under the boiler, so as to occasion the water to boil within it, a
circumstance which ought always to be carefully avoided. In that case,
the steam rising in the upper part of the boiler, and into the top pipe,
condenses there, and occasions violent concussions, the noise of which
often alarms the whole house, and leads to apprehensions of explosion,
which, however, is very unlikely to occur; but the concussions thus
produced injure the pipes, and may render them leaky: so that in regard
to these, and all other baths, &c., we may remark, that the pipes should
pass up and down in such parts of the house as will not be injured if
some leakage takes place; and under the bath itself should be a
sufficiently large leaden tray with a waste-pipe, to receive and carry
off any accidental drippings, which might injure the ceilings of the
rooms below. In all newly-built houses, two or three flues should be
left in proper places for the passage of ascending and descending
water-pipes; and these flues should in some way receive at their lower
part a little warm air in winter, to prevent the pipes freezing: the
same attention should also be paid to the situation of the cisterns of
water in houses, which should be kept within the house, and always
supplied with a very ample waste-pipe, to prevent the danger of
overflow. Cisterns thus properly placed, and carefully constructed,
should be supplied from the water-mains by pipes kept under ground, till
they enter the house, and not carried across the area, or immediately
under the pavement, where they are liable to freeze.

3. Baths are sometimes heated by steam, which has several advantages: it
may either be condensed directly into the water of the bath, or, if the
bath be of copper or tinned iron, it may be conducted into a casing upon
its outside, usually called a jacket; in the latter case there must be a
proper vent for the condensed water, and for the escape of air and waste
steam. Steam is also sometimes passed through a serpentine pipe, placed
at the bottom of the bath. But none of these methods are to be
recommended for adoption in private houses, and are only advisable in
hospitals, or establishments where steam boilers are worked for other
purposes than the mere heating of baths.

Many copper and tin baths have been lately constructed in London, with a
little furnace attached to one end, and surrounded with a case or
jacket, into which the water flows and circulates backwards and forwards
till the whole mass in the bath gets heated to the due degree. One of
the best of these is that constructed by Mr. Benham, of Wigmore Street.
The bath must be placed near the fire-grate, and the smoke-pipe of the
attached furnace be conducted up the chimney a certain way to secure a
sufficient draught to maintain combustion. The above bath, well managed,
heats the water from 50° to 98° in about 20 or 25 minutes, as I have
experimentally proved. When the proper temperature is attained, the fire
must of course be extinguished.


BDELLIUM. A gum resin, produced by an unknown plant which grows in
Persia and Arabia. It comes to us in yellowish or reddish pieces, smells
faintly, like myrrh, and consists of 59 resin, 9·2 gum, 30·6 bassorine,
and 1·2 ethereous oil.


BEER. (_Bière_, Fr. _Bier_, Germ.) The fermented infusion of malted
barley, flavoured with hops, constitutes the best species of beer; but
there are many beverages of inferior quality to which this name is
given, such as spruce beer, ginger beer, molasses beer, &c.; all of
which consist of a saccharine liquor, partially advanced into the vinous
fermentation, and flavoured with peculiar substances.

The ancients were acquainted with beer, and the Romans gave it the
appropriate name of _Cerevisia_ (quasi _Ceresia_), as being the product
of corn, the gift of Ceres. The most celebrated liquor of this kind in
the old time, was the _Pelusian_ potation, so called from the town where
it was prepared at the mouth of the Nile. Aristotle speaks of the
intoxication caused by beer; and Theophrastus very justly denominated it
the _wine of barley_. We may, indeed, infer from the notices found in
historians, that drinks analogous to our beer were in use among the
ancient Gauls, Germans, and in fact almost every people of our temperate
zone; and they are still the universal beverage in every land where the
vine is not an object of rustic husbandry.

The manufacture of beer, or the art of brewing, may be conveniently
considered under five heads:--

1. An examination of the natural productions which enter into its
composition; or of barley and hops.

2. The changes which barley must undergo to fit it for making beer; or
the processes of malting and mashing.

3. The formation of a proper wort from the mashed malt and hops.

4. The fermentation of that wort; and

5. The fining, ripening, and preservation of the beer.

I. _Of the materials._

1. Barley, wheat, maize, and several other kinds of corn are capable of
undergoing those fermentative changes, by which beer may be made; but
the first substance is by far the fittest. There are two species of
barley, the _hordeum vulgare_ or common barley, having two seeds
arranged in a row on its spikes; and the _hordeum hexastichon_, in which
three seeds spring from one point, so that its double row has apparently
six seeds. The former is the proper barley, and is much the larger sized
grain; the latter is little known in England, but is much cultivated in
Scotland under the name of _bear_ or _big_; being a hardy plant adapted
to a colder country. The finer the climate in which barley grows the
denser and larger its seed, and the thinner its husk; thus the Norfolk
and Suffolk barley is distinguished in these respects from that of
Aberdeenshire. Big is a less compact grain than barley; the weight of a
Winchester bushel (2150·42 cubic inches) of the former is only about 47
libs, while that of a bushel of the latter is nearly 51 libs. Their
constituents, however, bear much the same proportion to each other.

The quality of barley is proved not only by its density when dry, but by
the increase of volume which it acquires when steeped in water. Thus,

        100 measures of average English barley thereby swell into 124.
        100   --     of   --    Scotch ditto,                     121.
        100   --     of   --      --   bigg or bear,              118.
  Nay,  100 of very fine Suffolk barley have swollen into         183.
  While 100 of an inferior Scotch bigg became no more than        109.

This circumstance indicates so nearly the probable yield of malt, that
it is carefully attended to by the officers of excise, who gauge the
steep cistern, and levy their duty in conformity with the largest
volume, 100 pounds of good barley become almost one half heavier by the
absorption of moisture; and weigh upon an average 147 pounds; the best
of course taking up most water.

By chemical analysis barley flour seems to consist of 67·18 parts of
hordeine, or starch and gluten intimately combined, 7·29 of vegetable
fibre, 1·15 of coagulated albumen, 3·52 parts of gluten, 5·21 of sugar,
4·62 of gum, 0·24 of phosphate of lime, and 9·37 of water. The loss
amounted to 1·42. To these principles should be added a peculiar
volatile oil of a concrete nature, which is obtained during the process
of distilling fermented malt wash. (See WHISKEY.) It may also be
extracted from barley flour, by the solvent action of alcohol; and never
amounts to more than a few parts in the thousand. The husk also contains
some of that fetid oil. Proust thought that he had discovered in barley
a peculiar principle, to which he gave the name of _hordeine_, and which
he separated from starch by the action of both cold and boiling water.
He found that by treating barley meal successively with water, he
obtained from 89 to 90 parts of a farinaceous substance, composed of
from 32 to 33 of starch, and from 57 to 58 of _hordeine_. Einhof
obtained from barley seeds, 70·05 of flour, 18·75 of husks or bran, and
11·20 of water.

According to Proust hordeine is a yellowish powder, not unlike fine
saw-dust. It contains no azote, for it affords no ammonia by
distillation, and is therefore very dissimilar to gluten. In the
germination of barley, which constitutes the process of malting, the
proportion of hordeine is greatly diminished by its conversion into
sugar and starch. Other chemists suppose that the _hordeine_ of Proust
is merely a mixture of the bran of the barley with starch and gluten. It
is obvious that the subject stands in need of new chemical researches.
In barley the husk constitutes from one fourth to one fifth of the whole
weight; in oats it constitutes one third; and in wheat, one tenth. From
the analysis of barley flour recently made, it appears to consist in
1000 parts: of water, 100; albumine, 22·3; sugar, 56; gum or mucilage,
50; gluten, 37·6; starch, 720; phosphate of lime, 2·5.

2. The hop, _humulus lupulus_, the female flowers of the plant. Ives
first directed attention to a yellow pulverulent substance which invests
the scales of the catkins, amounting to about one eighth of their
weight; and referred to it the valuable properties which hops impart to
beer. We may obtain this substance by drying the hops at a temperature
of 86° F., introducing them into a coarse canvass bag, and shaking it so
that the yellow powder shall pass through the pores of the canvass. This
powder bears some resemblance to lycopodium. Of the 13 parts in 100 of
this powder, 4 parts are foreign matters, derived from the scales of the
cones; leaving 9 parts of a peculiar granular substance. When distilled
with water, this substance affords two per cent. of its weight (2/10 for
100 times the weight of hops) of a volatile colourless oil, to which the
plant owes its peculiar aroma. This oil dissolves in water in
considerable quantity. It appears to contain sulphur (for it blackens
solutions of silver), and also acetate of ammonia. No less than 65 per
cent. of the yellow dust is soluble in alcohol. This solution, treated
with water and distilled, leaves a resin, which amounts to 52·5 per
cent. It has no bitter taste, and is soluble in alcohol and ether. The
watery solution from which the resin was separated contains the bitter
substance which has been called _lupuline_ by Payen and Chevallier,
mixed with a little tannin and malic acid. To obtain this in a state of
purity, the free acid must be saturated with lime, the solution
evaporated to dryness, and the residuum must be treated with ether,
which removes a little resin; after which the _lupuline_ is dissolved
out by alcohol, which leaves the malate of lime. On evaporating away the
alcohol, the lupuline remains, weighing from 8·3 to 12·5 per cent. It is
sometimes white, or slightly yellowish, and opaque, sometimes orange
yellow, and transparent. At ordinary temperatures it is inodorous, but
when heated strongly it emits the smell of hops. It possesses the
characteristic taste and bitterness of the hop. Water dissolves it only
in the proportion of 5 per cent., but it thereby acquires a pale yellow
colour. Lupuline is neither acid nor alkaline; it is acted upon neither
by the dilute acids nor alkalies, nor by the solutions of the metallic
salts: it is quite soluble in alcohol, but hardly in ether. It contains
apparently no azote, for it affords no ammonia by destructive
distillation; but only an empyreumatic oil.

The yellow dust of hops contains, moreover, traces of a fatty matter,
gum, a small quantity of an azotised substance, and several saline
combinations in minute quantity. Boiling water dissolves from 19 to 31
per cent., of the contents of the dust, of which a large proportion is
resin. Ives thought that the scales of the catkins of hops, when freed
from the yellow powder, contained no principles analogous to it; but
Payen and Chevallier have proved the contrary. The cones of hop give up
to boiling alcohol 36 per cent. of soluble matter; while the same cones,
stripped of their yellow powder, yield only 26 per cent.; and further,
these chemists found the same principles in the different parts of the
hop, but in different proportions.

The packing of the hop catkins or cones is one of the most important
operations towards the preservation of this plant; and is probably the
cause of the enormous difference in value between the English and French
hops after a few years’ keeping. The former, at the end of six years,
possess still great value, and may be sold as an article only two or
three years old; while the latter have lost the greater part of their
value in three years, and are no more saleable at the end of four. In
France, it is packed merely by tramping it with the feet in sacks. Under
this slight pressure, large interstitial spaces are left amid the mass
of the hops, through which the air freely circulates, carrying off the
essential oil, and oxygenating some of the other proximate principles,
so as to render them inert. By the English method, on the contrary, the
hops, after being well rammed into strong sacks hung in frames, are next
subjected to the action of a hydraulic press. The valuable yellow powder
thus inclosed on every side by innumerable compact scales, is completely
screened from the contact of the atmosphere, and from all its
vicissitudes of humidity. Its essential oil, in particular the basis of
its flavour, is preserved without decay.

According to the experiments of Chevallier and Payen upon the hops of
England, Flanders, the Netherlands, and the department of the Vosges,
those of the county of Kent afforded the largest cones, and were most
productive in useful secreted and soluble matters. Next to them were the
hops of Alost.

The best hops have a golden yellow colour, large cones, an agreeable
aroma; when rubbed between the hands, they leave yellow traces,
powerfully odoriferous, without any broken portions of the plant, such
as leaves, stems, and scaly fragments. When alcohol is digested on good
hops, from 9 to 12 per cent. of soluble yellow matter may be obtained by
evaporating it to dryness. This is a good test of their quality.

The best-flavoured and palest hops are packed in sacks of fine canvass,
which are called pockets, and weigh about 1-1/2 cwt. each. These are
bought by the ale brewer. The stronger-flavoured and darker-coloured
hops are packed in bags of a very coarse texture like door-mats, called
hop bags: these contain generally about 3 cwt., and are sold to the
porter and beer brewers. After the end of a year or two, hops are
reckoned to have lost much of their marketable value, and are then sold
to the second-rate porter brewers, under the name of old hops. The
finest hops are grown in the neighbourhood of Canterbury; but those of
Worcester have an agreeable mildness of flavour, greatly admired by many
ale drinkers. When the bitter and aromatic principles disappear, the
hops are no better than so much chaff; therefore, an accurate chemical
criterion of their principles would be a great benefit to the brewer.

II. _Malting._--This process consists of three successive operations;
the steeping; the couching, sweating, and flooring; and the kiln-drying.

The _steeping_ is performed in large cisterns made of wood or stone,
which being filled with clear water up to a certain height, a quantity
of barley is shot into them, and well stirred about with rakes. The good
grain is heavy, and subsides; the lighter grains, which float on the
surface, are damaged, and should be skimmed off; for they would injure
the quality of the malt, and the flavour of the beer made with it. They
seldom amount to more than two per cent. More barley is successively
emptied into the steep cistern, till the water stands only a few inches,
about five, above its surface; when this is levelled very carefully, and
every light seed is removed. The steep lasts from forty to sixty hours,
according to circumstances; new barley requiring a longer period than
old, and bigg requiring much less time than barley.

During this steep, some carbonic acid is evolved from the grains, and
combines with the water, which, at the same time, acquires a yellowish
tinge, and a strawy smell, from dissolving some of the extractive matter
of the barley husks. The grain imbibes about one half its weight of
water, and increases in size by about one-fifth. By losing this extract,
the husk becomes about one seventieth lighter in weight, and paler in
colour.

The duration of the steep depends, in some measure, upon the temperature
of the air, and is shorter in summer than in winter. In general from 40
to 48 hours will be found sufficient for sound dry grain. Steeping has
for its object to expand the farina of the barley with humidity, and
thus prepare the seed for germination, in the same way as the moisture
of the earth prepares for the growth of the radicle and plumula in seed
sown in it. Too long continuance in the steep is injurious; because it
prevents the germination at the proper time, and thereby exhausts a
portion of the vegetative power: it causes also an abstraction of
saccharine matter by the water. The maceration is known to be complete
when the grain may be easily transfixed with a needle, and is swollen to
its full size. The following is reckoned a good test:--If a barley-corn,
when pressed between the thumb and fingers, continues entire in its
husk, it is not sufficiently steeped; but if it sheds its flour upon the
fingers, it is ready. When the substance exudes in the form of a milky
juice, the steep has been too long continued, and the barley is spoiled
for germination.

In warm weather it sometimes happens that the water becomes acescent
before the grain is thoroughly swelled. This accident, which is manifest
to the taste and smell, must be immediately obviated by drawing off the
foul water through the tap at the bottom of the cistern, and replacing
it with fresh cold water. It does no harm to renew it two or three times
at one steep.

The _couch_.--The water being drawn off, and occasionally a fresh
quantity passed through, to wash away any slimy matter which may have
been generated in warm weather, the barley is now laid upon the couch
floor of stone flags, in square heaps from 12 to 16 inches high, and
left in that position for 24 hours. At this period, the bulk of the
grain being the greatest, it may be gauged by the revenue officers if
they think fit. The moisture now leaves the surface of the barley so
completely, that it imparts no dampness to the hand. By degrees,
however, it becomes warm; the temperature rising 10° above the
atmosphere, while an agreeable fruity smell is evolved. At this time, if
the hand be thrust into the heap, it not only feels warm, but it gets
bedewed with moisture. At this sweating stage, the germination begins;
the fibrils of the radicle first sprout forth from the tip of every
grain, and a white elevation appears, that soon separates into three or
more radicles, which grow rapidly larger. About a day after this
appearance, the plumula peeps forth at the same point, proceeding thence
beneath the husk to the other end of the seed, in the form of a green
leaflet.

The greatest heat of the couch is usually about 96 hours after the
barley has been taken out of the steep. In consequence, the radicles
tend to increase in length with very great rapidity, and must be checked
by artificial means, which constitute the chief art of the maltster. He
now begins to spread the barley thinner on the floor, and turns it over
several times in the course of a day, bringing the portions of the
interior into the exterior surface. The depth, which was originally 15
or 16 inches, is lowered a little at every turning over, till it be
brought eventually down to three or four inches. Two turnings a day are
generally required. At this period of spreading or flooring, the
temperature in England is about 62°, and in Scotland 5 or 6 degrees
lower.

About a day after the radicles appear, the rudiments of the stem, or of
the plumula, sprout forth, called by the English maltsters the
_acrospire_. It issues from the same end of the seed as the radicle, but
turns round, and proceeds within the husk towards the other end, and
would there come forth as a green leaf, were its progress not arrested.
The malting, however, is complete before the acrospire becomes a leaf.

The barley couch absorbs oxygen and emits carbonic acid, just as animals
do in breathing, but to a very limited extent; for the grain loses only
three per cent. of its weight upon the malt floor, and a part of this
loss is due to waste particles. As the acrospire creeps along the
surface of the seed, the farina within undergoes a remarkable
alteration. The gluten and mucilage disappear, in a great measure, the
colour becomes whiter, and the substance becomes so friable that it
crumbles into meal between the fingers. This is the great purpose of
malting, and it is known to be accomplished when the plumula or
acrospire has approached the end of the seed. Now the further growth
must be completely stopped. Fourteen days may be reckoned the usual
duration of the germinating stage of the malting operations in England;
but in Scotland, where the temperature of the couch is lower, eighteen
days or even twenty-one, are sometimes required. The shorter the period
within the above limits, the more advantageous is the process to the
maltster, as he can turn over his capital the sooner, and his malt is
also somewhat the better. Bigg is more rapid in its germination than
barley, and requires to be still more carefully watched. In dry weather
it is sometimes necessary to water the barley upon the couch.

Occasionally the odour disengaged from the couch is offensive,
resembling that of rotten apples. This is a bad prognostic, indicating
either that the barley was of bad quality, or that the workmen, through
careless shovelling, have crushed a number of the grains in turning them
over. Hence when the weather causes too quick germination, it is better
to check it by spreading the heap out thinner than by turning it too
frequently over. On comparing different samples of barley, we shall find
that the best develope the germ or acrospire quicker than the radicles,
and thus occasion a greater production of the saccharine principle; this
conversion advances along with the acrospire, and keeps pace with it, so
that the portion of the seed to which it has not reached, is still in
its unaltered starchy state. It is never complete for any single
barleycorn till the acrospire has come to the end opposite to that from
which it sprung; hence one part of the corn may be sugary, while the
other is still insipid. If the grain were allowed to vegetate beyond
this term, the radicles being fully one third of an inch long, the
future stem would become visibly green in the exterior; it would shoot
forth rapidly, the interior of the grain would become milky, with a
complete exhaustion of all its useful constituents, and nothing but the
husk would remain.

In France, the brewers, who generally malt their barley themselves,
seldom leave it on the couch more than 8 or 10 days, which, even taking
into account the warmer climate of their country, is certainly too short
a period, and hence they make inferior wort to the English brewer, from
the same quantity of malt.

At the end of the germination, the radicles have become 1-1/2 longer
than the barley, and are contorted so that the corns hook into one
another, but the acrospire is just beginning to push through. A moderate
temperature of the air is best adapted to malting; therefore it cannot
be carried on well during the heat of summer or the colds of winter.
Malt-floors should be placed in substantial thick-walled buildings,
without access of the sun, so that a uniform temperature of 59° or 60°
may prevail inside. Some recommend them to be sunk a little under the
surface of the ground, if the situation be dry.

During germination a remarkable change has taken place in the substance
of the grain. The glutinous constituent has almost entirely disappeared,
and is supposed to have passed into the matter of the radicles, while a
portion of the starch is converted into sugar and mucilage. The change
is similar to what starch undergoes when dissolved in water, and
digested in a heat of about 160°F. along with a little gluten. The
thick paste becomes gradually liquid, transparent, and sweet tasted, and
the solution contains now, sugar and gum, mixed with some unaltered
starch. The gluten suffers a change at the same time, and becomes
acescent, so that only a certain quantity of starch can be thus
converted by a quantity of gluten. By the artificial growth upon the
malt-floor, all the gluten and albumen present in barley are not
decomposed, and only about one half of the starch is converted into
sugar; the other half, by a continuance of the germination, would only
go to the growth of the roots and stems of the plant; but it receives
its nearly complete conversion into sugar without any notable waste of
substance in the brewer’s operation of mashing.

The _kiln-drying_.--When the malt has become perceptibly dry to the hand
upon the floor, it is taken to the kiln, and dried hard with artificial
heat, to stop all further growth, and enable it to be kept, without
change, for future use, at any time. The malt-kiln, which is
particularly described in the next page, is a round or a square chamber,
covered with perforated plates of cast iron, whose area is heated by a
stove or furnace, so that not merely the plates on which the malt is
laid are warmed, but the air which passes up through the stratum of malt
itself, with the effect of carrying off very rapidly the moisture from
the grains. The layer of malt should be about 3 or 4 inches thick, and
evenly spread, and its heat should be steadily kept at from the 90th to
the 100th degree of Fahrenheit’s scale, till the moisture be mostly
exhaled from it. During this time the malt must be turned over at first
frequently, and latterly every three or four hours. When it is nearly
dry, its temperature should be raised to from 145° to 165°F., and it
must be kept at this heat till it has assumed the desired shade of
colour, which is commonly a brownish-yellow or a yellowish-brown. The
fire is now allowed to die out, and the malt is left on the plates till
it has become completely cool; a result promoted by the stream of cool
air, which now rises up through the bars of the grate; or the thoroughly
dry browned malt may, by damping the fire, be taken hot from the plates,
and cooled upon the floor of an adjoining apartment. The prepared malt
must be kept in a dry loft, where it can be occasionally turned over
till it is used. The period of kiln-drying should not be hurried. Many
persons employ two days in this operation.

According to the colour and the degree of drying, malt is distributed
into three sorts; pale, yellow, and brown. The first is produced when
the highest heat to which it has been subjected is from 90° to 100° F.;
the amber yellow, when it has suffered a heat of 122°; and the brown
when it has been treated as above described. The black malt used by the
porter brewer to colour his beer, has suffered a much higher heat, and
is partially charred. The temperature of the kiln should, in all cases,
be most gradually raised, and most equably maintained. If the heat be
too great at the beginning, the husk gets hard dried, and hinders the
evaporation of the water from the interior substance; and should the
interior be dried by a stronger heat, the husk will probably split, and
the farina become of a horny texture, very refractory in the mash-tun.
In general, it is preferable to brown malt, rather by a long-continued
moderate heat, than by a more violent heat of shorter duration, which is
apt to carbonise a portion of the mucilaginous sugar, and to damage the
article. In this way, the sweet is sometimes converted into a bitter
principle.

During the kiln-drying, the roots and acrospire of the barley become
brittle, and fall off; and are separated by a wire sieve whose meshes
are too small to allow the malt itself to pass through.

A quantity of good barley, which weighs 100 pounds, being judiciously
malted, will weigh, after drying and sifting, 80 pounds. Since the raw
grain, dried by itself at the same temperature as the malt, would lose
12 per cent. of its weight in water, the malt process dissipates out of
these remaining 88 pounds, only 8 pounds, or 8 per cent. of the raw
barley. This loss consists of--

  1-1/2 per cent. dissolved out in the steep water,
  3       --      dissipated in the kiln,
  3       --      by the falling of the fibrils,
    1/2   --      of waste.

The bulk of good malt exceeds that of the barley from which it was made,
by about 8 or 9 per cent.

The operation of kiln-drying is not confined to the mere expulsion of
the moisture from the germinated seeds; but it serves to convert into
sugar a portion of the starch which remained unchanged, and that in a
twofold way; first, by the action of the gluten upon the fecula at an
elevated temperature, as also by the species of roasting which the
starch undergoes, and which renders it of a gummy nature. (See STARCH.)
We shall have a proof of this explanation, if we dry one portion of the
malt in a naturally dry atmosphere, and another in a moderately warm
kiln; the former will yield less saccharine extract than the latter.
Moreover, the kiln-dried malt has a peculiar, agreeable, and faintly
burned taste, probably from a small portion of empyreumatic oil formed
in the husk, and which not only imparts its flavour to the beer, but
also contributes to its preservation. It is therefore obvious, that the
skilful preparation of the malt must have the greatest influence both on
the quantity and quality of the worts to be made from it. If the
germination be pushed too far, a part of the extractible matter is
wasted; if it has not advanced far enough, the malt will be too raw, and
too much of its substance will remain as an insoluble starch; if it is
too highly kiln-dried, a portion of its sugar will be caramelised, and
become bitter; and if the sweating was imperfect or irregular, much of
the barley may be rendered lumpy and useless. Good malt is
distinguishable by the following characters:--

The grain is round and full, breaks freely between the teeth, and has a
sweetish taste, an agreeable smell, and is full of a soft flour from end
to end. It affords no unpleasant flavour on being chewed; it is not
hard, so that when drawn along an oaken table across the fibres, it
leaves a white streak, like chalk. It swims upon water, while unmalted
barley sinks in it. Since the quality of the malt depends much on that
of the barley, the same sort only should be used for one malting. New
barley germinates quicker than old, which is more dried up; a couch of a
mixture of the two would be irregular, and difficult to regulate.

[Illustration: 97 98 99 100]

_Description of the malt kiln._--_Figs._ 97, 98, 99, 100. exhibit the
construction of a well-contrived _malt kiln_. _Fig._ 97. is the ground
plan; _fig._ 98. is the vertical section; and _figs._ 99. and 100., a
horizontal and vertical section in the line of the malt-plates. The same
letters denote the same parts in each of the figures. A cast-iron
cupola-shaped oven is supported in the middle, upon a wall of brickwork
four feet high; and beneath it, are the grate and its ash-pit. The smoke
passes off through two equi-distant pipes into the chimney. The oven is
surrounded with four pillars, on whose top a stone lintel is laid: _a_
is the grate, 9 inches below the sole of the oven _b_; _c c c c_ are the
four nine-inch strong pillars of brickwork which bear the lintel _m_; _d
d d d d d_ are strong nine-inch pillars, which support the girder and
joists upon which perforated plates repose; _e_ denotes a vaulted arch
on each of the four sides of the oven; _f_ is the space between the kiln
and the side arch, into which a workman may enter, to inspect and clean
the kiln; _g g_, the walls on either side of the kiln, upon which the
arches rest, _h_, the space for the ashes to fall; _k_, the fire-door of
the kiln; _l l_, junction-pieces to connect the pipes _r r_ with the
kiln; the mode of attaching them is shown in _fig._ 99. These
smoke-pipes lie about three feet under the iron plates, and at the same
distance from the side walls; they are supported upon iron props, which
are made fast to the arches. In _fig._ 98., _u_ shows their section; at
_s s_, _fig._ 99., they enter the chimney, which is provided with two
register or damper plates, to regulate the draught through the pipes.
These registers are represented by _t t_, _fig._ 100., which shows a
perpendicular section of the chimney. _m_, _fig._ 98., is the lintel
which causes the heated air to spread laterally instead of ascending in
one mass in the middle, and prevents any combustible particles from
falling upon the iron cupola. _n n_ are the main girders of iron for the
iron beams _o o_, upon which the perforated plates _p_ lie; _q_, _fig._
98., is the vapour pipe in the middle of the roof, which allows the
steam of the drying malt to escape. The kiln may be heated either with
coal or wood.

The size of this kiln is about 20 feet square; but it may be made
proportionally either smaller or greater. The perforated floor should be
large enough to receive the contents of one steep or couch.

The perforated plate might be conveniently heated by steam pipes, laid
zig-zag, or in parallel lines under it; or a wire-gauze web might be
stretched upon such pipes. The wooden joists of a common floor would
answer perfectly to support this steam-range, and the heat of the pipes
would cause an abundant circulation of air. For drying the pale malt of
the ale brewer, this plan is particularly well adapted.

The kiln-dried malt is sometimes ground between stones in a common corn
mill, like oatmeal; but it is more generally crushed between iron
rollers, at least for the purposes of the London brewers.

[Illustration: 101 102]

The _crushing mill_.--The cylinder malt-mill is constructed as shown in
_fig._ 101, 102. I is the sloping-trough, by which the malt is let down
from its bin or floor to the hopper A of the mill, whence it is
progressively shaken in between the rollers B D. The rollers are of
iron, truly cylindrical, and their ends rest in bearers of hard brass,
fitted into the side frames of iron. A screw E goes through the upright,
and serves to force the bearer of the one roller towards that of the
other, so as to bring them closer together when the crushing effect is
to be increased. G is the square end of the axis, by which one of the
rollers may be turned either by the hand or by power; the other derives
its rotatory motion from a pair of equal-toothed wheels H, which are
fitted to the other end of the axes of the rollers. _d_ is a catch which
works into the teeth of a ratchet-wheel on the end of one of the rollers
(not shown in this view). The lever _c_ strikes the trough _b_ at the
bottom of the hopper, and gives it the shaking motion for discharging
the malt between the rollers, from the slide sluice _a_. _e e_, _fig._
101., are scraper-plates of sheet iron, the edges of which press by a
weight against the surfaces of the rollers, and keep them clean.

Instead of the cylinders, some employ a crushing mill of a
conical-grooved form like a coffee mill, upon a large scale. (_See the
general plan, infrà._)

The _mashing and boiling_.--Mashing is the operation by which the wort
is extracted, or eliminated from the malt, and whereby a
saccharo-mucilaginous extract is made from it. The malt should not in
general be ground into a fine meal, for in that case it would be apt to
form a cohesive paste with hot water, or to set, as it is called, and to
be difficult to drain. In crushed malt, the husk remains nearly entire,
and thus helps to keep the farinaceous particles open and porous to the
action of the water. The bulk of the crushed malt is about one-fifth
greater than that of the whole, or one bushel of malt gives a bushel and
a quarter of crushed malt. This is frequently allowed to lie a few days
in a cool place, in order that it may attract moisture from the air,
which it does very readily by its hygrometric power. Thus, the
farinaceous substance which had been indurated in the kiln, becomes
soft, spongy, and fit for the ensuing process of watery extraction.

Mashing has not for its object merely to dissolve the sugar and gum
already present in the malt, but also to convert into a sweet mucilage
the starch which had remained unchanged during the germination. We have
already stated that starch, mixed with gluten, and digested for some
time with hot water, becomes a species of sugar. This conversion takes
place in the mash-tun. The malted barley contains not only a portion of
gluten, but _diastase_ more than sufficient to convert the starch
contained in it, by this means, into sugar.

The researches of Payen and Persoz show, that the mucilage formed by the
reaction of malt upon starch, may either be converted into sugar, or be
made into permanent gum, according to the temperature of the water in
which the materials are digested. We take of pale barley malt, ground
fine, from 6 to 10 parts, and 100 parts of starch; we heat, by means of
a water-bath, 400 parts of water in a copper, to about 80°F.; we then
stir in the malt, and increase the heat to 140°F., when we add the
starch, and stir well together. We next raise the temperature to 158°,
and endeavour to maintain it constantly at that point, or at least to
keep it within the limits of 167° on the one side, and 158° on the
other. At the end of 20 or 30 minutes, the original milky and pasty
solution becomes thinner, and soon after as fluid nearly as water. This
is the moment in which the starch is converted into gum, or into that
substance which the French chemists call _dextrine_, from its power of
polarising light to the right hand, whereas common gum does it to the
left. If this merely mucilaginous solution, which seems to be a mixture
of gum with a little liquid starch and sugar, be suitably evaporated, it
may serve for various purposes in the arts to which gum is applied, but
with this view, it must be quickly raised to the boiling point, to
prevent the farther operation of the malt upon it. If we wish, on the
contrary, however, to promote the saccharine fermentation, for the
formation of beer, we must maintain the temperature at between 158° and
167° for three or four hours, when the greatest part of the gum will
have passed into sugar, and by evaporation of the liquid at the same
temperature, a starch syrup may be obtained like that procured by the
action of sulphuric acid upon starch. The substance, which operates in
the formation of sugar, or is the peculiar ferment of the sugar
fermentation, may be considered as a residuum of the gluten or vegetable
albumen in the germinating grain: it is reckoned by Payen and Persoz, a
new proximate principle called _diastase_, which is formed during
malting, in the grains of barley, oats, and wheat, and may be separated
in a pure state, if we moisten the malt flour for a few minutes in cold
water, press it out strongly, filter the solution, and heat the clear
liquid in a water bath, to the temperature of 158°. The greater part of
that albuminous azotised substance is thus coagulated, and is to be
separated by a fresh filtration; after which, the clear liquid is to be
treated with alcohol, when a flocky precipitate appears, which is
_diastase_. To purify it still further, especially from the azotised
matter, we should dissolve it in water, and precipitate again with
alcohol. When dried at a low temperature, it appears as a solid white
substance, which contains no azote; is insoluble in alcohol, but
dissolves in water and proof spirit. Its solution is neutral and
tasteless; when left to itself, it changes with greater or less rapidity
according to the temperature, and becomes sour at a temperature of from
149° to 167°. It has the property of converting starch into gum
(dextrine) and sugar, and indeed, when sufficiently pure, with such
energy that one part of it disposes 2000 parts of dry starch to that
change, but it operates the quicker the greater its quantity. Whenever
the solution of diastase with starch or with dextrine is heated to the
boiling point, it loses the sugar-fermenting property. One hundred parts
of well-malted starch appear to contain about one part of this
substance.

We can now understand the theory of malting, and the limits between
which the temperature of the liquor, ought to be maintained in this
operation; namely, the range between 157° and 160°F. It has been
ascertained as a principle in mashing, that the best and soundest
extract of the malt, is to be obtained, first of all, by beginning to
work with water at the lowest of these heats, and to conclude the mash
with water at the highest. Secondly, not to operate the extraction at
once with the whole of the water that is to be employed; but with
separate portions and by degrees. The first portion is added with the
view of penetrating equally the crushed malt, and of extracting the
already formed sugar; the next for effecting the sugar fermentation by
the action of the diastase. By this means also, the starch is not
allowed to run into a cohesive paste, and the extract is more easily
drained from the poorer mass, and comes off in the form of a nearly
limpid wort. The thicker moreover, or the less diluted the mash is, so
much the easier is the wort fined in the boiler or copper by the
coagulation of the albuminous matter: these principles illustrate, in
every condition, the true mode of conducting the mashing process; but
different kinds of malt require a different treatment. Pale and slightly
kilned malt requires a somewhat lower heat than malt highly kilned,
because the former has more undecomposed starch, and is more ready to
become pasty. The former also, for the same reason, needs a more
leisurely infusion than the latter, for its conversion into mucilaginous
sugar. The more sugar the malt contains, the more is its saccharine
fermentation accelerated by the action of the diastase. What has been
here said of pale malt, is still more applicable to the case of a
mixture of raw grain with malt, for it requires still gentler heats, and
more cautious treatment.

III. The mash-tun is a large circular tub with a double bottom; the
uppermost of which is called a false bottom, and is pierced with many
holes. There is a space of about 2 or 3 inches between the two, into
which the stopcocks enter, for letting in the water and drawing off the
wort. The holes of the false bottom should be burned, and not bored, to
prevent the chance of their filling up by the swelling of the wood,
which would obstruct the drainage: the holes should be conical, and
largest below, being about 3/8 of an inch there, and 1/8 at the upper
surface. The perforated bottom must be fitted truly at the sides of the
mash-tun, so that no grains may pass through. The mashed liquor is let
off into a large back, from which it is pumped into the wort coppers.
The mash-tun is provided with a peculiar rotatory apparatus for
agitating the crushed grains and water together, which we shall
presently describe. The size of the wort copper is proportional to the
amount of the brewing, and it must, in general, be at least so large as
to operate upon the whole quantity of wort made from one mashing; that
is, for every quarter of malt mashed, the copper should contain 140
gallons. The mash-tun ought to be at least a third larger, and of a
conical form, somewhat wider below than above. The quantity of water to
be employed for mashing, or the extraction of the wort, depends upon the
greater or less strength to be given to the beer. The seeds of the
crushed malt, after the wort is drawn off, retain still about 32 gallons
of water for every quarter of malt. In the boiling, and evaporation from
the coolers, 40 gallons of water are dissipated from one quarter of
malt; constituting 72 gallons in all. If 13 quarters of barley be taken
to make 1500 gallons of beer, 2400 gallons of water must therefore be
required for the mashing. This example will give an idea of the
proportions for an ordinary quality of beer.

When the mash is to begin, the copper must be filled with water, and
heated. As soon as the water has attained the heat of 145° in summer, or
167° in winter, 600 gallons of it are to be run off into the mash-tun,
and the 13 quarters of crushed malt are to be gradually thrown in and
well intermixed by proper agitation, so that it may be uniformly
moistened, and no lumps may remain. After continuing the agitation in
this way for one half or three-quarters of an hour, the water in the
copper will have approached to its boiling point, when 450 gallons at
the temperature of about 200° are to be run into the mash-tun, and the
agitation is to be renewed till the whole assumes an equally fluid
state: the tun is now to be well covered for the preservation of its
heat, and to be allowed to remain at rest for an hour, or an hour and a
half. The mean temperature of this mash may be reckoned at about 145°.
The time which is necessary for the transmuting heat of the remaining
starch into sugar depends on the quality of the malt. Brown malt
requires less time than pale malt, and still less than a mixture with
raw grain, as already explained. After the mash has rested the proper
time, the tap of the tun is opened, and the clear wort is to be drawn
out into the under back. If the wort that first flows is turbid, it must
be returned into the tun, till it runs clear. The amount of this first
wort may be about 675 gallons. Seven hundred and fifty gallons of water
at the temperature of 200° are now to be introduced up through the
drained malt, into the tun, and the mixture is to be agitated till it
becomes uniform, as before. The mash-tun is then to be covered, and
allowed to remain at rest for an hour. The temperature of this mash is
from 167° to 174°. While the second mash is making, the worts of the
first are to be pumped into the wort copper, and set a-boiling as
speedily as possible. The wort of the second mash is to be drawn off at
the proper time, and added to the copper as fast as it will receive it,
without causing the ebullition to stop.

A third quantity of water amounting to 600 gallons, at 200°, is to be
introduced into the mash-tun, and after half an hour, is to be drawn
off, and either pumped into the wort copper, or reserved for mashing
fresh malt, as the brewer may think fit.

The quantity of extract, per barrel weight, which a quarter of malt
yields to wort, amounts to about 84 lbs. The wort of the first extract
is the strongest; the second contains, commonly, one-half the extract of
the first; and the third, one-half of the second; according to
circumstances.

To measure the degrees of concentration of the worts drawn off from the
tun, a particular form of hydrometer, called a saccharometer, is
employed, which indicates the number of pounds weight of liquid
contained in a barrel of 36 gallons imperial measure. Now, as the barrel
of water weighs 360 lbs., the indication of the instrument when placed
in any wort, shows by how many pounds a barrel of that wort is heavier
than a barrel of water; thus, if the instrument sinks with its poise
till the mark 10 is upon a line with the surface of the liquid, it
indicates that a barrel of that wort weighs ten pounds more than a
barrel of water. See SACCHAROMETER.

Or, supposing the barrel of wort weighs 396 lbs., to convert that number
into specific gravity, we have the following simple rule:--

  360 : 396 ∷ 100 : 1·100;

at which density, by my experiments, the wort contains 25 per cent., of
solid extract.

Having been employed to make experiments on the density of worts, and
the fermentative changes which they undergo, for the information of a
committee of the House of Commons, which sat in July and August, 1830, I
shall here introduce a short abstract of that part of my evidence which
bears upon the present subject.

My first object was to clear up the difficulties which, to common
apprehension, hung over the matter, from the difference in the scales
of the saccharometers in use among the brewers and distillers of England
and Scotland. I found that one quarter of good malt would yield to the
porter brewer a barrel Imperial measure of wort, at the concentrated
specific gravity of 1·234. Now, if the decimal part of this number be
multiplied by 360, being the number of pounds weight of water in the
barrel, the product will denote the excess in pounds, of the weight of a
barrel of such concentrated wort, over that of a barrel of water, and
that product is, in the present case, 84·24 pounds.

Mr. Martineau, jun., of the house of Messrs. Whitbread and Company, and
a gentleman connected with another great London brewery, had the
kindness to inform me that their average product from a quarter of malt
was a barrel of 84 lbs. gravity. It is obvious, therefore, that by
taking the mean operation of two such great establishments, I must have
arrived very nearly at the truth.

It ought to be remarked that such a high density of wort as 1·234 is not
the result of any direct experiment in the brewery, for infusion of malt
is never drawn off so strong; that density is deduced by computation
from the quantity and quality of several successive infusions; thus,
supposing a first infusion of the quarter of malt to yield a barrel of
specific gravity 1·112, a second to yield a barrel at 1·091, and a third
a barrel at 1·031, we shall have three barrels at the mean of these
three numbers, or one barrel at their sum, equal to 1·234.

I may here observe that the arithmetical mean or sum is not the true
mean or sum of the two specific gravities; but this difference is either
not known or disregarded by the brewers. At low densities this
difference is inconsiderable, but at high densities it would lead to
serious errors. At specific gravity 1·231, wort or syrup contains one
half of its weight of solid pure saccharum, and at 1·1045 it contains
one fourth of its weight; but the brewer’s rule, when here applied,
gives for the mean specific gravity 1·1155 = (1·231 + 1·000)/2.

The contents in solid saccharine matter at that density are however
27-1/4 per cent. showing the rule to be 2-1/4 lbs. wrong in excess on
100 lbs., or 9 lbs. per barrel.

The specific gravity of the solid dry extract of malt wort is 1·264; it
was taken in oil of turpentine, and the result reduced to distilled
water as unity. Its specific volume is 0·7911, that is, 10 lbs. of it
will occupy the volume of 7·911 lbs. of water. The mean specific
gravity, by computation of a solution of that extract in its own weight
of water, is 1·1166; but by experiment, the specific gravity of that
solution is 1·216, showing considerable condensation of volume in the
act of combination with water.

The following Table shows the relation between the specific gravities of
solutions of malt extract, and the per-centage of solid extract they
contain:

  +-----+------+------------+-------+--------+
  |Extr.|Water.|Malt Extract| Sugar |Specific|
  |Malt.|      |  in 100.   |in 100.|gravity.|
  +-----+------+------------+-------+--------+
  |600 +|  600 |   50·00    | 47·00 | 1·2180 |
  |600 +|  900 |   40·0     | 37·00 | 1·1670 |
  |600 +| 1200 |   33·3     | 31·50 | 1·1350 |
  |600 +| 1500 |   28·57    | 26·75 | 1·1130 |
  |600 +| 1800 |   25·00    | 24·00 | 1·1000 |
  +-----+------+------------+-------+--------+

The extract of malt was evaporated to dryness, at a temperature of about
250° F., without the slightest injury to its quality, or any
empyreumatic smell. Bate’s tables have been constructed on solutions of
sugar, and not with solutions of extract of malt, or they agree
sufficiently well with the former, but differ materially from the
latter. Allan’s tables give the amount of a certain form of solid
saccharine matter extracted from malt, and dried at 175° F., in
correspondence to the specific gravity of the solution; but I have found
it impossible to make a solid extract from infusions of malt, except at
much higher temperatures than 175° F. Indeed, the numbers on Allan’s
saccharometer scale clearly show that his extract was by no means dry:
thus, at 1·100 of gravity he assigns 29·669 per cent. of solid
saccharine matter; whereas there is at that density of solid extract
only 25 per cent. Again, at 1·135, Allan gives 40 parts per cent. of
solid extract, whereas there are only 33-1/3 present.

By the triple mashing operations above described, the malt is so much
exhausted that it can yield no further extract useful for strong beer or
porter. A weaker wort might no doubt still be drawn off for small beer,
or for contributing a little to the strength of the next mashing of
fresh malt. But this I believe is seldom practised by respectable
brewers, as it impoverishes the grains which they dispose of for feeding
cattle.

The wort should be transferred into the copper, and made to boil as soon
as possible, for if it remains long in the under-back it is apt to
become acescent. The steam moreover raised from it in the act of boiling
serves to screen it from the oxygenating or acidifying influence of the
atmosphere. Until it begins to boil, the air should be excluded by some
kind of a cover.

Sometimes the first wort is brewed by itself into strong ale, the second
by itself into an intermediate quality; and the third into small beer;
but this practice is not much followed in this country.

We shall now treat of the boiling in of the hops. The wort drawn from
the mash-tun, whenever it is pumped into the copper, must receive its
allowance of hops. Besides evaporating off a portion of the water, and
thereby concentrating the wort, boiling has a twofold object. In the
first place, it coagulates the albuminous matter, partly by the heat,
and partly by the principles in the hops, and thereby causes a general
clarification of the whole mass, with the effect of separating the muddy
matters in a flocculent form. Secondly, during the ebullition, the
residuary starch and hordeine of the malt are converted into a limpid
sweetish mucilage, the _dextrine_ above described; while some of the
glutinous stringy matter is rendered insoluble by the tannin principle
of the hops, which favours still further the clearing of the wort. By
both operations the keeping quality of the beer is improved. This boil
must be continued during several hours; a longer time for the stronger,
and a shorter for the weaker beers. There is usually one seventh or one
sixth part of the water dissipated in the boiling copper. This process
is known to have continued a sufficient time, if the separation of the
albuminous flocks is distinct, and if these are found, by means of a
proof gauge suddenly dipped to the bottom, to be collected there, while
the supernatant liquor has become limpid. Two or three hours’ boil is
deemed long enough in many well-conducted breweries; but in some of
those in Belgium, the boiling is continued from 10 to 15 hours, a period
certainly detrimental to the aroma derived from the hop.

Many prefer adding the hops when the wort has just come to the boiling
point. Their effect is to repress the further progress of fermentation,
and especially the passage into the acetous stage, which would otherwise
inevitably ensue in a few days. In this respect, no other vegetable
production hitherto discovered can be a substitute for the hop. The
odorant principle is not so readily volatilised as would at first be
imagined; for when hop is mixed with strong beer wort, and boiled for
many hours, it can still impart a very considerable degree of its
flavour to weaker beer. By mere infusion in hot beer or water, without
boiling, the hop loses very little of its soluble principles. The tannin
of the hop combines, as we have said, with the vegetable albumen of the
barley, and helps to clarify the liquor. Should there be a deficiency of
albumen and gluten, in consequence of the mashing having been done at
such a heat as to have coagulated them beforehand, the defect may be
remedied by the addition of a little gelatine to the wort copper, either
in the form of calf’s foot, or of a little isinglass. If the hops be
boiled in the wort for a longer period than 5 or 6 hours, they lose a
portion of their fine flavour; but if their natural flavour be rank, a
little extra boiling improves it. Many brewers throw the hops in upon
the surface of the boiling wort, and allow them to swim there for some
time, that the steam may penetrate them, and open their pores for a
complete solution of their principles when they are pushed down into the
liquor. It is proper to add the hops in considerable masses, because in
tearing them asunder, some of the lupuline powder is apt to be lost.

The quantity of hop to be added to the wort varies according to the
strength of the beer, the length of time it is to be kept, or the heat
of the climate where it is intended to be sent. For strong beer, 4-1/2
lbs. of hops are required to a quarter of malt, when it is to be highly
aromatic and remarkably clear. For the stronger kinds of ale and porter,
the rule, in England, is to take a pound of hops for every bushel of
malt, or 8 lbs. to a quarter. Common beer has seldom more than a quarter
of a pound of hops to the bushel of malt.

It has been attempted to form an extract of hops by boiling in covered
vessels, so as not to lose the oil, and to add this instead of the hop
itself to the beer. On the great scale this method has no practical
advantage, because the extraction of the hop is perfectly accomplished
during the necessary boiling of the wort, and because the hop operates
very beneficially, as we have explained, in clarifying the beer. Such an
extract, moreover, could be easily adulterated.

_Of the Coolers._--The contents of the copper are run into what is
called the hop-back, on the upper part of which is fixed a drainer, to
keep back the hops. The pump is placed in the hop-back, for the purpose
of raising the wort to the coolers, usually placed in an airy situation
upon the top of the brewery. Two coolers are indispensable when we make
two kinds of beer from the same brewing, and even in single brewings,
called _gyles_, if small beer is to be made. One of these coolers ought
to be placed above the level of the other. As it is of great consequence
to cool the worts down to the fermenting pitch as fast as possible,
various contrivances have been made for effecting this purpose. The
common cooler is a square wooden cistern, about 6 inches deep, and of
such an extent of surface that the whole of one boil may only occupy 2
inches, or thereabouts, of depth in it. For a quantity of wort equal to
about 1500 gallons its area should be at least 54 feet long and 20 feet
wide. The seams of the cooler must be made perfectly water-tight and
smooth, so that no liquor may lodge in them when they are emptied. The
utmost cleanliness is required, and an occasional sweetening with
lime-water.

The hot wort reaches the cooler at a temperature of from 200° to 208°,
according to the power of the pump. Here it should be cooled to the
proper temperature for the fermenting tun, which may vary from 54° to
64°, according to circumstances. The refrigeration is accomplished by
the evaporation of a portion of the liquor: it is more rapid in
proportion to the extent of the surface, to the low temperature, and the
dryness of the atmosphere surrounding the cooler. The renewal of a body
of cool dry air by the agency of a fan, may be employed with great
advantage. The cooler itself must be so placed that its surface shall be
freely exposed to the prevailing wind of the district, and be as free as
possible from the eddy of surrounding buildings. It is thought by many,
that the agitation of the wort during its cooling, is hurtful. Were the
roof made moveable, so that the wort could be readily exposed, in a
clear night, to the aspect of the sky, it would cool rapidly by
evaporation, on the principles explained by Dr. Wells, in his “Essay on
Dew.”

When the cooling is effected by evaporation alone, the temperature falls
very slowly, even in cold air, if it be loaded with moisture. But when
the air is dry, the evaporation is vigorous, and the moisture exhaled
does not remain incumbent on the liquor, as in damp weather, but is
diffused widely in space. Hence we can understand how wort cools so
rapidly in the spring and autumn, when the air is generally dry, and
even more quickly than in winter, when the air is cooler, but loaded
with moisture. In fact, the cooling process goes on better when the
atmosphere is from 50° to 55°, than when it falls to the freezing point,
because in this case, if the air be still, the vapours generated remain
on the surface of the liquor, and prevent further evaporation. In summer
the cooling can take place only during the night.

In consequence of the evaporation during this cooling process, the bulk
of the worts is considerably reduced; thus, if the temperature at the
beginning was 208°, and if it be at the end 64°, the quantity of water
necessary to be evaporated to produce this refrigeration would be nearly
1/8 of the whole, putting radiation and conduction of heat out of the
question. The effect of this will be a proportional concentration of the
beer.

The period of refrigeration in a well-constructed cooler, amounts to 6
or 7 hours in favourable weather, but to 12 or 15 in other
circumstances. The quality of the beer is much improved by shortening
this period; because, in consequence of the great surface which the wort
exposes to the air, it readily absorbs oxygen, and passes into the
acetous fermentation with the production of various mouldy spots; an
evil to which ill-hopped beer is particularly liable. Various schemes
have been contrived to cool wort, by transmitting it through the
convolutions of a pipe immersed in cold water. The best plan is to
expose the hot wort for some hours freely to the atmosphere and the
cooler, when the loss of heat is most rapid by evaporation and other
means, and when the temperature falls to 100°, or thereby, to transmit
the liquor through a zig-zag pipe, laid almost horizontally in a trough
of cold water. The various methods described under _Refrigerator_ are
more complex, but they may be practised in many situations with
considerable advantage.

Whilst the wort reposes in the cooler, it lets fall a slight sediment,
which consists partly of fine flocks of coagulated albumen combined with
tannin, and partly of starch, which had been dissolved at the high
temperature, and separates at the lower. The wort should be perfectly
limpid, for a muddy liquor never produces transparent beer. Such beer
contains, besides mucilaginous sugar and gum, usually some starch, which
even remains after the fermentation, and hinders its clarifying, and
gives it a tendency to sour. The wort contains more starch the hotter it
has been mashed, the less hops have been added, and the shorter time it
has been boiled. The presence of starch in the wort may be made manifest
by adding a little solution of iodine in alcohol to it, when it will
become immediately blue. We thus see that the tranquil cooling of wort
in a proper vessel has an advantage over cooling it rapidly by a
refrigeratory apparatus. When the wort is sufficiently cool, it is let
down into the fermenting tun. In this transfer, the cooling might be
carried several degrees lower, were the wort made to pass down through a
tube inclosed in another tube, along which a stream of cold water is
flowing in the opposite direction, as we have described in the sequel of
ACETIC ACID. These fermenting tuns are commonly called _gyle-tuns_, or
working tuns, and are either square or circular, the latter being
preferable on many accounts.

IV. _Of the Fermentation._--In the great London breweries, the size of
these fermenting tuns is such that they contain from 1200 to 1500
barrels. The quantity of wort introduced at a time must, however, be
considerably less than the capacity of the vessel, to allow room for the
head of yeast which rises during the process; if the vessel be
cylindrical, this head is proportional to the depth of the worts. In
certain kinds of fermentation, it may rise to a third of that depth. In
general, the fermentation proceeds more uniformly and constantly in
large masses, because they are little influenced by vicissitudes of
temperature; smaller vessels, on the other hand, are more easily
handled. The _general_ view of fermentation will be found under that
title; I shall here make a few remarks on what is peculiar to beer.
During the fermentation of wort, a portion of its saccharine matter is
converted into alcohol, and wort thus changed, is beer. It is necessary
that this conversion of the sugar be only partial, for beer which
contains no undecomposed sugar would soon turn sour, and even in the
casks its alcohol undergoes a slow fermentation into vinegar. The amount
of this excess of sugar is greater in proportion to the strength of the
wort, since a certain quantity of alcohol, already formed, prevents the
operation of the ferment on the remaining wort. Temperature has the
greatest influence upon the fermentation of wort. A temperature of from
55° to 60° of the liquor, when that of the atmosphere is 55°, is most
advantageous for the commencement. The warmth of the wort as it comes
into the gyle-tun must be modified by that of the air in the apartment.
In winter, when this apartment is cold, the wort should not be cooled
under 64° or 60°, as in that case the fermentation would be tedious or
interrupted, and the wort liable to spoil or become sour. In summer,
when the temperature of the place rises to above 75°, the wort should be
cooled, if possible, down to 55°, for which purpose it should be let in
by the system of double pipes, above mentioned. The higher the
temperature of the wort, the sooner will the fermentation begin and end,
and the less is it in our power to regulate its progress. The expert
brewer must steer a middle course between these two extremes, which
threaten to destroy his labours. In some breweries a convoluted pipe is
made to traverse or go round the sides of the gyle-tun, through which
warm water is allowed to flow in winter, and cold in summer, so as to
modify the temperature of the mass to the proper fermenting pitch. If
there be no contrivance of this kind, the apartment may be cooled in
summer, by suspending wet canvas opposite the windows in warm weather,
and kindling a small stove within it in cold.

When the wort is discharged into the gyle-tun, it must receive its dose
of yeast, which has been previously mixed with a quantity of the wort,
and left in a warm place till it has begun to ferment. This mixture,
called _lobb_, is then to be put into the tun, and stirred well through
the mass. The yeast should be taken from similar beer. Its quantity must
depend upon the temperature, strength, and quantity of the wort. In
general, one gallon of yeast is sufficient to set 100 gallons of wort in
complete fermentation. An excess of yeast is to be avoided, lest the
fermentation should be too violent, and be finished in less than the
proper period of 6 or 8 days. More yeast is required in winter than
summer; for, at a temperature of 50°, a double quantity may be used to
that at 68°.

Six or eight hours after adding the yeast, the tun being meanwhile
covered, the fermentation becomes active: a white milky-looking froth
appears, first on the middle, and spreads gradually over the whole
surface; but continues highest in the middle, forming a frothy
elevation, the height of which increases with the progress of the
fermentation, and whose colour gradually changes to a bright brown, the
result, apparently, of the oxidation of the extractive contained in this
yeasty top. This covering screens the wort from the contact of the
atmospherical air. During this time, there is a perpetual disengagement
of carbonic acid gas, which is proportional to the quantity of sugar
converted into alcohol. The warmth of the fermenting liquid increases at
the same time, and is at a maximum when the fermentation has come to its
highest point. This increase of temperature amounts to from 9° to 14° or
upwards, and is the greater the more rapid the fermentation. But in
general, the fermentation is not allowed to proceed so far in the
gyle-tun, for after it is advanced a little way, the beer is _cleansed_,
that is, drawn off into other vessels, which are large barrels set on
end, with large openings in their top, furnished with a sloping tray for
discharging an excess of yeast into the wooden trough, in which the
_stillions_ stand. These _stillions_ are placed in communication with a
store-tub, which keeps them always full, by hydrostatic pressure, so
that the head of yeast may spontaneously flow over, and keep the body of
liquor in the cask clean. This apparatus will be explained in describing
the brewery plant. See the _figures, infrà_.

It must be observed, that the quantity of yeast, and the heat of
fermentation, differ for every different quality of beer. For mild ale,
when the fermentation has reached 75°, its first flavour begins; at 80°
the flavour increases; at 85° it approaches the high flavour; at 90° it
is high; but it may be carried to 100° and upwards, for particular
purposes. A wort of 30 lbs. per barrel (sp. gr. 1·088), ought to
increase about 15°, so that in order to arrive at 80°, it should be set
at 65°. The quantity of yeast for such an ale should be from 2 to 3 lbs.
per barrel. The higher the heat, the less yeast is necessary. If the
heat of the fermentation should at any time fall, it must be raised by a
supply of fresh yeast, well stirred in; but this practice is not
advisable in general, because rousing the worts in the gyle-tun is apt
to communicate a rank flavour of yeast to the ale. It is the practice of
many experienced brewers to look every 2 hours into the gyle-tun,
chiefly with the view of observing the progress of the heat, which is
low at first, but afterwards often increases half a degree per hour, and
subsequently declines, as the fermentation approaches its conclusion,
till at length the heat becomes uniform, or sometimes decreases, before
the fermentation is finished, especially where the quantity operated
upon is small.

Some brewers recommend, when the fermentation is carried to its utmost
period, to add about 7 lbs. of wheat or bean flour to a gyle-tun of 25
or 30 barrels, at the time of _cleansing_, so as to quicken the
discharge of the yeast, by disengagement of more carbonic acid. The
flour should be whisked up in a pail, with some of the beer, till the
lumps are broken, and then poured in. By early cleansing, the yeast is
preserved longer in a state proper for a perfect fermentation than by a
contrary practice.

For old ale, which is to be long kept, the heat of the fermentation
should not exceed 75°, but a longer time is required to complete the
fermentation and ensure the future good flavour of the ale.

For porter, the general practice is, to use from 4 to 4-1/2 lbs. of hops
per barrel for keeping; though what is termed mild or mixing porter, has
not more than 3 or 3-1/2 lbs. The heat of fermentation must not exceed
70°, and begin about 60°. If the heat tend to increase much above that
pitch in the gyle-tun, the porter should be _cleansed_, by means of the
_stillions_. At this period of the fermentation, care should be taken
that the sweetness of the malt be removed, for which purpose more yeast
may be used than with any other beer of the same strength. The quantity
is from 3 to 4 lbs. per barrel, rousing the wort in the gyle-tun every 2
hours in the day-time.

When the plan of _cleansing_ casks is not employed, the yeast is removed
from the surface of the fermenting tun by a skimmer, and the clear beer
beneath is then drawn off into the ripening tuns, called _store-vats_,
in which it is mixed up with different brewings, to suit the taste of
the customers. This transfer must take place whenever the extrication of
carbonic acid has nearly ceased; lest the alcohol formed should dissolve
some of the floating yeast, acquire thereby a disagreeable taste, and
pass partially into the acetous state.

In this process, during the formation of vinous spirit at the expense of
the sugar, the albumen and gluten diffused through the beer, being acted
upon by the alcohol, become insoluble; one portion of them is buoyed to
the top with the carbonic acid gas, to form the frothy yeast; and
another portion falls to form the bottom barm. The former consists of
the same materials as the wort, with a large proportion of gluten, which
forms its active constituent; the latter is a peculiar deposit,
consisting of the same gluten mixed with the various dense impurities of
the wort, and may be also used as a ferment, but is cruder than the
floating yeast. The amount of yeast is proportional to the activity of
the fermentation, or extrication of carbonic acid gas, as also to the
heat of the mashing process, and the quantity of starch or flour
unaltered by germination. Pale malt affords usually, more yeast than
malt highly kilned. When the yeast becomes excessive, from too violent
fermentation, it should be skimmed off from time to time, which will
tend to cool the liquor and moderate the intestine changes.

After the beer is let down into the close store-tuns in the cellar, an
obscure fermentation goes on, for a considerable period in its body,
which increases its spirituous strength, and keeps up in it a constant
impregnation of carbonic acid gas, so as to render it lively and
agreeable to the taste, when it is casked off for sale. It would appear,
that beer is never stationary in quality, while it is contained in the
tuns; for the moment when it ceases to improve by the decomposition of
its residuary sugar, it begins to degenerate into vinegar. This result
may be produced either by the exhaustion of the saccharine, or by the
fermentative matter. The store cellar should therefore be under ground,
free from alternations of temperature, vibrations of carriages, and as
cool as possible. In the great London breweries, the fermentation is
rendered very complete in the cleansing butts; so that a slow and steady
ripening is ensured in the great store-tuns. The gyle-tuns are too
capacious to permit the fermentation to be finished, with either safety
or sufficient dispatch in them.

V. OF RIPENING DIFFERENT KINDS OF BEER.--The varieties of beer depend
either upon the difference of their materials, or from a different
management of the brewing processes.

With regard to the materials, beers differ in the proportion of their
malt, hops, and water; and in the different kinds of malt or other
grain. To the class of table or small beers, all those sorts may be
referred whose specific gravity does not exceed 1·025, which contain
about 5 per cent. of malt extract, or nearly 18 pounds per barrel. Beers
of middling strength may be reckoned those between the density of 1·025
and 1·040; which contain, at the average, 7 per cent., or 25 pounds per
barrel. The latter may be made with 400 quarters of malt to 1500 barrels
of beer. Stronger beers have a specific gravity of from 1·050 to 1·080,
and take from 45 to 75 quarters of malt to the same quantity of beer.
The strongest beer found in the market is some of the English and Scotch
ales, for which from 18 to 27 quarters of malt are taken for 1500
gallons of beer. Good porter requires from 16 to 18 quarters for that
quantity. Beers are sometimes made with the addition of other
farinaceous matter to the malt; but when the latter constitutes the main
portion of the grain, the malting of the other kinds of corn becomes
unnecessary, for the diastase of the barley-malt changes the starch into
sugar during the mashing operation. Even with entirely raw grain, beer
is made in some parts of the Continent, the brewers trusting the
conversion of the starch into sugar to the action of the gluten alone,
at a low mashing temperature, on the principle of Saussure’s and
Kirchoff’s researches.

The colour of the beer depends upon the colour of the malt, and the
duration of the boil in the copper. The pale ale is made, as we have
stated, from steam or sun-dried malt, and the young shoots of the hop;
the deep yellow ale from a mixture of pale yellow and brown malt; and
the dark brown beer from well-kilned and partly carbonised malt, mixed
with a good deal of the pale, to give body. The longer and more strongly
heated the malt has been in the kiln, the less weight of extract,
_cæteris paribus_, does it afford. In making the fine mild ales, high
temperatures ought to be avoided, and the yeast ought to be skimmed off,
or allowed to flow very readily from its top, by means of the cleansing
butt system, so that little ferment being left in it to decompose the
rest of the sugar, the sweetness may remain unimpaired. With regard to
porter, in certain breweries, each of the three kinds of malt employed
for it is separately mashed, after which the first and the half of the
second wort is boiled along with the whole of the hops, and thence
cooled and set to ferment in the gyle-tun. The third drawn wort, with
the remaining half of the second, is then boiled with the same hops,
saved by the drainer, and, after cooling, added to the former in the
gyle-tun, when the two must be well roused together.

It is obvious, from the preceding development of principles, that all
amylaceous and saccharine materials, such as potatoes, beans, turnips,
as well as cane and starch syrup, molasses, &c., may be used in brewing
beer. When, however, a superior quality of brown beer is desired, malted
barley is indispensable, and even with these substitutes a mixture of it
is most advantageous. The washed roots of the common carrot, of the red
and yellow beet, or of the potato, must be first boiled in water, and
then mashed into a pulp. This pulp must be mixed with water in the
copper, along with wheaten or oat meal, and the proper quantity of hops,
then boiled during 8 or 9 hours. This wort is to be cooled in the usual
way, and fermented, with the addition of yeast. A much better process is
that now practised, on a considerable scale, at Strasbourg, in making
the ale, for which that city is celebrated. The mashed potatoes are
mixed with from a twentieth to a tenth of their weight of finely ground
barley malt, and some water. The mixture is exposed, in a water-bath, to
a heat of 160° F. for four hours, whereby it passes into a saccharine
state, and may then be boiled with hops, cooled, and properly fermented
into good beer.

Maize, or Indian corn, has also been employed to make beer; but its
malting is somewhat difficult on account of the rapidity and vigour with
which its radicles and plumula sprout forth. The proper mode of causing
it to germinate is to cover it, a few inches deep, with common soil, in
a garden or field, and to leave it there till the bed is covered with
green shoots of the plant. The corn must be then lifted, washed, and
exposed to the kiln.

_The Difference of the Fermentation._--The greater or less rapidity with
which the worts are made to ferment has a remarkable influence upon the
quality of the beer, especially in reference to its fitness for keeping.
The wort is a mucilaginous solution in which the yeastly principles,
eliminated by the fermentation, will, if favoured by regular and slow
intestine movements, completely rise to the surface, or sink to the
bottom, so as to leave the body fine. But, when the action is too
violent, these barmy glutinous matters get comminuted and dispersed
through the liquor, and can never afterwards be thoroughly separated. A
portion of the same feculent matter becomes, moreover, permanently
dissolved, during this furious commotion, by the alcohol that is
generated. Thus the beer loses not merely its agreeable flavour and
limpidity, but is apt to spoil from the slightest causes. The slower,
more regularly progressive, and less interrupted, therefore, the
fermentation is, so much better will the product be.

Beer, in its perfect condition, is an excellent and healthful beverage,
combining, in some measure, the virtues of water, of wine, and of food,
as it quenches thirst, stimulates, cheers, and strengthens. The vinous
portion of it is the alcohol, proceeding from the fermentation of the
malt sugar. Its amount, in common strong ale or beer, is about 4 per
cent., or four measures of spirits, specific gravity 0·825 in 100
measures of the liquor. The best brown stout porter contains 6 per
cent., the strongest ale even 8 per cent.; but common beer only one. The
nutritive part of the beer is the undecomposed gum-sugar, and the
starch-gum, not changed into sugar. Its quantity is very variable,
according to the original starch of the wort, the length of the
fermentation, and the age of the beer.

The main feature of good beer is fine colour and transparency; the
production of which is an object of great interest to the brewer.
Attempts to clarify it in the cask seldom fail to do it harm. The only
thing that can be used with advantage for _fining_ foul or muddy beer,
is isinglass. For porter, as commonly brewed, it is frequently had
recourse to. A pound of good isinglass will make about 12 gallons of
_finings_. It is cut into slender shreds, and put into a tub with as
much vinegar or hard beer as will cover it, in order that it may swell
and dissolve. In proportion as the solution proceeds, more beer must be
poured upon it, but it need not be so acidulous as the first, because,
when once well softened by the vinegar, it readily dissolves. The
mixture should be frequently agitated with a bundle of rods, till it
acquires the uniform consistence of thin treacle, when it must be
equalised still more by passing through a tammy cloth, or a sieve. It
may now be made up with beer to the proper measure of dilution. The
quantity generally used is from a pint to a quart per barrel, more or
less, according to the foulness of the beer. But before putting it into
the butt, it should be diffused through a considerable volume of the
beer with a whisk, till a frothy head be raised upon it. It is in this
state to be poured into the cask, briskly stirred about; after which the
cask must be bunged down for at least 24 hours, when the liquor should
be limpid. Sometimes the beer will not be improved by this treatment;
but this should be ascertained beforehand, by drawing off some of the
beer into a cylindric jar or phial, and adding to it a little of the
finings. After shaking and setting down the glass, we shall observe
whether the feculencies begin to collect in flocky parcels, which slowly
subside; or whether the isinglass falls to the bottom without making any
impression upon the beer. This is always the case when the fermentation
is incomplete, or a secondary decomposition has begun. Mr. Jackson has
accounted for this clarifying effect of isinglass in the following way.

The isinglass, he thinks, is first of all rather diffused mechanically,
than chemically dissolved, in the sour beer or vinegar, so that when the
finings are put into the foul beer, the gelatinous fibres, being set
free in the liquor, attract and unite with the floating feculencies,
which before this union were of the same specific gravity with the beer,
and therefore could not subside alone; but having now acquired
additional weight by the coating of fish-glue, precipitate as a
flocculent magma. This is Mr. Jackson’s explanation; to which I would
add, that if there be the slightest disengagement of carbonic acid gas,
it will keep up an obscure locomotion in the particles, which will
prevent the said light impurities, either alone or when coated with
isinglass, from subsiding. The beer is then properly enough called
_stubborn_ by the coopers. But the true theory of the action of
isinglass is, that the tannin of the hops combines with the fluid
gelatine, and forms a flocculent mass, which envelopes the muddy
particles of the beer, and carries them to the bottom as it falls, and
forms a sediment. When after the finings are poured in, no proper
precipitate ensues, it may be made to appear by the addition of a little
decoction of hop.

Mr. Richardson, the author of the well-known brewer’s saccharometer,
gives the following as the densities of different kinds of beer:--

  +-----------------------+------------------+-----------------+
  |         Beer.         |Pounds per Barrel.|Specific Gravity.|
  +-----------------------+------------------+-----------------+
  |Burton ale, 1st sort   |     40 to 43     | 1·111 to 1·120  |
  |            2d ditto   |     35 to 40     | 1·097 to 1·111  |
  |            3d ditto   |     28 to 33     | 1·077 to 1·092  |
  |Common ale             |     25 to 27     | 1·070 to 1·073  |
  |Ditto ditto            |        21        | 1·058           |
  |Porter, common sort    |        18        | 1·050           |
  |Ditto, double          |        20        | 1·055           |
  |Ditto, brown stout     |        23        | 1·064           |
  |Ditto, best brown stout|        26        | 1·072           |
  |Common small beer      |         6        | 1·014           |
  |Good table beer        |     12 to 14     | 1·033 to 1·039  |
  +-----------------------+------------------+-----------------+

_Of Returns or Malt Residuums._--When small beer is brewed after ale or
porter, only one mash is to be made; but where this is not done, there
may be two mashes, in order to economise malt to the utmost. We may let
on the water at 160° or 165°, in any convenient quantity, infuse for an
hour or thereby, then run it off, and pump into the copper, putting some
hops into it, and causing it to boil for an instant; when it may be
transferred to the cooler. A second mash or return may be made in the
same manner, but at a heat 5° lower; and then disposed of in the boiler
with some hops, which may remain in the copper during the night at a
scalding heat, and may be discharged into the cooler in the morning.
These two returns are to be let down into the under-back immediately
before the next brewing, and thence heated in the copper for the next
mashing of fresh malt, instead of hot water, commonly called _liquor_,
in the breweries. But allowance must be made, in the calculation of the
worts, for the quantity of fermentable matter in these two returns. The
nett aggregate saving is estimated from the gravity of the return taken
when cold in the cooler. A slight economy is also made in the extra
boiling of the used hops. The lapse of a day or two between the
consecutive brewings is no objection to the method of _returns_, because
they are too weak in saccharine matter to run any risk of fermentation.

In conclusion, it may be remarked that Mr. Richardson somewhat
underrates the gravity of porter, which is now seldom under 20 lbs. per
barrel. The criterion for transferring from the gyle-tun to the
cleansing butts is the attenuation caused by the production of alcohol
in the beer: when that has fallen to 10 lbs. or 11 lbs., which it
usually does in 48 hours, the cleansing process is commenced. The heat
is at this time generally 75°, if it was pitched at 65°; for the heat
and the attenuation go hand in hand.

About thirty years ago, it was customary for the London brewers of
porter, to keep immense stocks of it for eighteen months or two years,
with the view of improving its quality. The beer was pumped from the
cleansing butts into store-vats, holding from twenty to twenty-five
gyles or brewings of several hundred barrels each. The store-vats had
commonly a capacity of 5000 or 6000 barrels; and a few were double, and
one was treble, this size. The porter, during its long repose in these
vats, became fine, and by obscure fermentation its saccharine mucilage
was nearly all converted into vinous liquor, and dissipated in carbonic
acid. Its hop-bitter was also in a great degree decomposed. _Good hard
beer_ was the boast of the day. This was sometimes softened by the
publican, by the addition of some mild new-brewed beer. Of late years,
the taste of the metropolis has undergone such a complete revolution in
this respect, that nothing but the mildest porter will now go down.
Hence, six weeks is a long period for beer to be kept in London; and
much of it is drunk when only a fortnight old. Ale is for the same
reason come greatly into vogue; and the two greatest porter houses,
Messrs. Barclay, Perkins, & Co., and Truman, Hanbury, & Co., have become
extensive and successful brewers of mild ale, to please the changed
palate of their customers.

We shall add a few observations upon the brewing of Scotch ale. This
beverage is characterised by its pale amber colour, and its mild
balsamic flavour. The bitterness of the hop is so mellowed with the
malt, as not to predominate. The ale of Preston Pans is, in fact, the
best substitute for wine which barley has hitherto produced. The low
temperature at which the Scotch brewer pitches his fermenting tun
restricts his labours to the colder months of the year. He does nothing
during four of the summer months. He is extremely nice in selecting his
malt and hops; the former being made from the best English barley, and
the latter being the growth of Farnham or East Kent. The yeast is
carefully looked after, and measured into the fermenting tun in the
proportion of one gallon to 240 gallons of wort.

Only one mash is made by the Scotch ale brewer, and that pretty strong;
but the malt is exhausted by eight or ten successive sprinklings of
liquor (hot water) over the goods (malt), which are termed in the
vernacular tongue, _sparges_. These waterings percolate through the malt
on the mash-tun bottom, and extract as much of the saccharine matter as
may be sufficient for the brewing. By this simple method much higher
specific gravities may be obtained than would be practicable by a second
mash. With malt, the infusion or saccharine fermentation of the
_diastase_ is finished with the first mash; and nothing remains but to
wash away from the goods the matter which that process has rendered
soluble. It will be found on trial that 20 barrels of wort drawn from a
certain quantity of malt, by two successive mashings, will not be so
rich in fermentable matter as 20 barrels extracted by ten successive
sparges of two barrels each. The grains always remain soaked with wort
like that just drawn off, and the total residual quantity is three
fourths of a barrel for every quarter of malt. The gravity of this
residual wort will on the first plan be equal to that of the second
mash; but on the second plan, it will be equal only to that of the tenth
sparge, and will be more attenuated in a very high geometrical ratio.
The only serious objection to the sparging system is the loss of time by
the successive drainages. A mash-tun with a steam jacket, promises to
suit the sparging system well; as it would keep up an uniform
temperature in the goods, without requiring them to be sparged with very
hot liquor.

The first part of the Scotch process seems of doubtful economy; for the
mash liquor is heated so high as 180°. After mashing for about half an
hour, or till every particle of the malt is thoroughly drenched, the tun
is covered, and the mixture left to infuse about three hours; it is then
drained off into the under-back, or preferably into the wort copper.

After this wort is run off, a quantity of liquor (water), at 180° of
heat, is sprinkled uniformly over the surface of the malt; being first
dashed on a perforated circular board, suspended horizontally over the
mash-tun, wherefrom it descends like a shower upon the whole of the
goods. The percolating wort is allowed to flow off, by three or more
small stopcocks round the circumference of the mash-tun, to insure the
equal diffusion of the liquor.

The first sparge being run off in the course of twenty minutes, another
similar one is affused; and thus in succession till the whole of the
drainage, when mixed with the first mash-wort, constitutes the density
adapted to the quality of the ale. Thus, the strong worts are prepared,
and the malt is exhausted either for table beer, or for a _return_, as
pointed out above. The last sparges are made 5° or 6° cooler than the
first.

The quantity of hops seldom exceeds four pounds to the quarter of malt.
The manner of boiling the worts is the same as that above described; but
the conduct of the fermentation is peculiar. The heat is pitched at 50°,
and the fermentation continues from a fortnight to three weeks. Were
three brewings made in the week, seven or eight working tuns would thus
be in constant action; and, as they are usually in one room, and some of
them at an _elevation_ of temperature of 15°, the apartment must be
propitious to fermentation, however low its heat may be at the
commencement. No more yeast is used than is indispensable: if a little
more be needed, it is made effective by rousing up the tuns twice a day
from the bottom.

When the progress of the attenuation becomes so slack as not to exceed
half a pound in the day, it is prudent to cleanse, otherwise the top
harm might re-enter the body of the beer, and it would become
_yeast-bitten_. When the ale is cleansed, the head, which has not been
disturbed for some days, is allowed to float on the surface till the
whole of the _then_ pure ale is drawn off into the casks. This top is
regarded as a sufficient preservative against the contact of the
atmosphere. The Scotch do not skim their tuns, as the London ale brewers
commonly do. The Scotch ale, when so cleansed, does not require to be
set upon close stillions. It throws off little or no yeast, because the
fermentation was nearly finished in the tun. The strength of the best
Scotch ale ranges between 32 and 44 pounds to the barrel; or it has a
specific gravity of from 1·088 to 1·122, according to the price at which
it is sold. In a good fermentation, seldom more than a fourth of the
original gravity of the wort remains at the period of the cleansing.
Between one third and one fourth is the usual degree of attenuation.
Scotch ale soon becomes fine, and is seldom racked for the home market.
The following table will show the progress of fermentation in a brewing
of good Scotch ale:--

  20 barrels of mash-worts of 42-1/2 pounds gravity = 860·6
  20        -- returns         6-1/10               = 122
                                                      -----
                                                 12 ) 982·6
                                                      -----
       pounds weight of extract per quarter of malt =  81

Fermentation:--

  March 24. pitched the tun at 51°: yeast 4 gallons.
                               Temp.  Gravity.
        25.                    52°    41 pounds.
        28.                    56°    39
        30.                    60°    34
  April  1.                    62°    32
         4.                    65°    29 added 1 lb. of yeast.
         5.                    66°    25
         6.                    67°    23
         7.                    67°    20
         8.                    66°    18
         9.                    66°    15
        10.                    64°    14·5 cleansed[7].

  [7] BREWING (Society for diffusing Useful Knowledge), p. 156.

The following table shows the origin and the result of fermentation, in
a number of practical experiments:--

  +--------+----------+-----------+----------+------------+
  |Original| Lbs. per |  Specific | Lbs. per |Attenuation,|
  |Gravity |Barrel of |  Gravity  |Barrel of |or Saccharum|
  |of the  |Saccharine|of the Ale.|Saccharine| decomposed.|
  | Worts. | Matter.  |           | Matter.  |            |
  +--------+----------+-----------+----------+------------+
  | 1·0950 |  88·75   |  1·0500   |  40·25   |   0·478    |
  | 1·0918 |  85·62   |  1·0420   |  38·42   |   0·552    |
  | 1·0829 |  78·125  |  1·0205   |  16·87   |   0·787    |
  | 1·0862 |  80·625  |  1·0236   |  20·00   |   0·757    |
  | 1·0780 |  73·75   |  1·0280   |  24·25   |   0·698    |
  | 1·0700 |  65·00   |  1·0285   |  25·00   |   0·615    |
  | 1·1002 |  93·75   |  1·0400   |  36·25   |   0·613    |
  | 1·1025 |  95·93   |  1·0420   |  38·42   |   0·600    |
  | 1·0978 |  91·56   |  1·0307   |  27·00   |   0·705    |
  | 1·0956 |  89·37   |  1·0358   |  32·19   |   0·640    |
  | 1·1130 | 105·82   |  1·0352   |  31·87   |   0·661    |
  | 1·1092 | 102·187  |  1·0302   |  26·75   |   0·605    |
  | 1·1171 | 110·00   |  1·0400   |  36·25   |   0·669    |
  | 1·1030 |  96·40   |  1·0271   |  23·42   |   0·757    |
  | 1·0660 |  61·25   |  1·0214   |  17·80   |   0·709    |
  +--------+----------+-----------+----------+------------+

The second column here does not represent, I believe, the solid extract,
but the pasty extract obtained as the basis of Mr. Allen’s
saccharometer, and therefore each of its numbers is somewhat too high.
The last column, also, must be in some measure erroneous, on account of
the quantity of alcohol dissipated during the process of fermentation.
It must be likewise incorrect, because the density due to the saccharine
matter will be partly counteracted, by the effect of the alcohol present
in the fermented liquor. In fact, the attenuation does not correspond to
the strength of the wort; being greatest in the third brewing, and
smallest in the first. The quantity of yeast for the above ale brewings
in the table was, upon an average, one gallon for 108 gallons; but it
varied with its quality, and with the state of the weather, which, when
warm, permits much less to be used with propriety.

The good quality of the malt, and the right management of the mashing,
may be tested by the quantity of saccharine matter contained in the
successively drawn worts. With this view, an aliquot portion of each of
them should be evaporated by a safety-bath heat to a nearly concrete
consistence, and then mixed with twice its volume of strong spirit of
wine. The truly saccharine substance will be dissolved, while the starch
and other matters will be separated; after which the proportions of each
may be determined by filtration and evaporation. Or an equally correct,
and much more expeditious, method of arriving at the same result would
be, after agitating the viscid extract with the alcohol in a tall glass
cylinder, to allow the insoluble fecula to subside, and then to
determine the specific gravity of the supernatant liquid by a
hydrometer. The additional density which the alcohol has acquired will
indicate the quantity of malt sugar which it has received. The following
table, constructed by me, at the request of Henry Warburton, Esq., M.
P., chairman of the Molasses Committee of the House of Commons in 1830,
will show the brewer the principle of this important inquiry. It
exhibits the quantity in grains weight of sugar requisite to raise the
specific gravity of a gallon of spirit of different densities to the
gravity of water = 1·000.

  Specific Gravity of   Grains, Weight of Sugar in the
        Spirit.                Gallon Imperial.
         0·995                     0·980
         0·990                     1·890
         0·985                     2·800
         0·980                     3·710
         0·975                     4·690
         0·970                     5·600
         0·965                     6·650
         0·960                     7·070
         0·955                     8·400
         0·950                     9·310

The immediate purpose of this table was to show the effect of saccharine
matter in disguising the presence or amount of alcohol in the weak
feints of the distiller. But a similar table might easily be
constructed, in which, taking a uniform quantity of alcohol of 0·825,
for example, the quantity of sugar in any wort-extract would be shown by
the increase of specific gravity which the alcohol received from
agitation with a certain weight of the wort, inspissated to a nearly
solid consistence by a safety-pan, made on the principle of my patent
sugar-pan. (See SUGAR.) Thus, the normal quantities being 1000 grain
measures of alcohol, and 100 grains by weight of inspissated
mash-extract, the hydrometer would at once indicate, by help of the
table, first, the quantity per cent. of truly saccharine matter, and
next, by subtraction, that of farinaceous matter present in it.

[Illustration: 103]

_Plan, Machinery, and Utensils of a great Brewery._--_Figs._ 103. and
104. represent the arrangement of the utensils and machinery in a porter
brewery on the largest scale; in which, however, it must be observed
that the elevation _fig._ 103. is in a great degree imaginary as to the
plane upon which it is taken; but the different vessels are arranged so
as to explain their uses most readily, and at the same time to
preserve, as nearly as possible, the relative positions which are
usually assigned to each in works of this nature.

The malt for the supply of the brewery is stored in vast granaries or
malt-lofts, usually situated in the upper part of the buildings. Of
these, I have been able to represent only one, at A, _fig._ 103.: the
others, which are supposed to be on each side of it, cannot be seen in
this view. Immediately beneath the granary A, on the ground floor, is
the mill; in the upper story above it, are two pairs of rollers, _fig._
101, 102, and 103, under _a_, _a_, for bruising or crushing the grains
of the malt. In the floor beneath the rollers are the mill-stones _b_,
_b_, where the malt is sometimes ground, instead of being merely bruised
by passing between the rollers, under _a_, _a_.

The malt, when prepared, is conveyed by a trough into a chest _d_, to
the right of _b_, from which it can be elevated by the action of a
spiral screw, _fig._ 105., enclosed in the sloping tube _e_, into the
large chest or binn B, for holding ground malt, situated immediately
over the mash-tun D. The malt is reserved in this binn till wanted, and
it is then let down into the mashing-tun, where the extract is obtained
by hot water supplied from the copper G, seen to the right of B.

The water for the service of the brewery is obtained from the well E,
seen beneath the mill to the left, by a lifting pump worked by the steam
engine; and the forcing-pipe _f_ of this pump conveys the water up to
the large reservoir or water-back F, placed at the top of the
engine-house. From this cistern, iron pipes are laid to the copper G (on
the right-hand side of the figure), as also to every part of the
establishment where cold water can be wanted for cleaning and washing
the vessels. The copper G can be filled with cold water by merely
turning a cock; and the water, when boiled therein, is conveyed by the
pipe _g_ into the bottom of the mash-tun D. It is introduced beneath a
false bottom, upon which the malt lies, and, rising up through the holes
in the false bottom, it extracts the saccharine matter from the malt; a
greater or less time being allowed for the infusion, according to
circumstances. The instant the water is drawn off from the copper, fresh
water must be let into it, in order to be ready for boiling the second
mashing; because the copper must not be left empty for a moment,
otherwise the intense heat of the fire would destroy its bottom. For the
convenience of thus letting down at once as much liquor as will fill the
lower part of the copper, a pan or second boiler is placed over the top
of the copper, as seen in _fig._ 103.; and the steam rising from the
copper communicates a considerable degree of heat to the contents of the
pan, without any expense of fuel. This will be more minutely explained
hereafter. (_See fig._ 107.)

During the process of mashing, the malt is agitated in the mash-tun, so
as to expose every part to the action of the water. This is done by a
mechanism contained within the mash-tun, which is put in motion by a
horizontal shaft above it, H, leading from the mill. The mash machine is
shown separately in _fig._ 106. When the operation of mashing is
finished, the wort or extract is drained down from the malt into the
vessel I, called the _under-back_, immediately below the mash-tun, of
like dimensions, and situated always on a lower level, for which reason
it has received this name. Here the wort does not remain longer than is
necessary to drain off the whole of it from the tun above. It is then
pumped up by the three-barrelled pump _k_, into the pan upon the top of
the copper, by a pipe which cannot be seen in this section. The wort
remains in the pan until the water for the succeeding mashes is
discharged from the copper. But this delay is no loss of time, because
the heat of the copper, and the steam arising from it, prepare the wort,
which had become cooler, for boiling. The instant the copper is emptied,
the first wort is let down from the pan into the copper, and the second
wort is pumped up from the under-back into the upper pan. The proper
proportion of hops is thrown into the copper through the near hole, and
then the door is shut down, and screwed fast, to keep in the steam, and
cause it to rise up through pipes into the pan. It is thus forced to
blow up through the wort in the pan, and communicates so much heat to
it, or water, called _liquor_ by the brewers, that either is brought
near to the boiling point. The different worts succeed each other
through all the different vessels with the greatest regularity, so that
there is no loss of time, but every part of the apparatus is constantly
employed. When the ebullition has continued a sufficient period to
coagulate the grosser part of the extract, and to evaporate part of the
water, the contents of the copper are run off through a large cock into
the _jack-back_ K, below G, which is a vessel of sufficient dimensions
to contain it, and provided with a bottom of cast-iron plates,
perforated with small holes, through which the wort drains and leaves
the hops. The hot wort is drawn off from the jack-back through the pipe
_h_ by the three-barrelled pump, which throws it up to the coolers L, L,
L; this pump being made with different pipes and cocks of communication,
to serve all the purposes of the brewery except that of raising the cold
water from the well. The coolers L, L, L, are very shallow vessels,
built over one another in several stages: and that part of the building
in which they are contained is built with lattice-work or or shutter
flaps, on all sides, to admit free currents of air. When the wort is
sufficiently cooled to be put to the first fermentation, it is conducted
in pipes from all the different coolers to the large fermenting vessel
or gyle-tun M, which, with another similar vessel behind it, is of
sufficient capacity to contain all the beer of one day’s brewings.

Whenever the first fermentation is concluded, the beer is drawn off from
the great fermenting vessel M, into the small fermenting casks or
cleansing vessels N, of which there are a great number in the brewery.
They are placed four together, and to each four a common spout is
provided to carry off the yeast, and conduct it into the troughs _n_,
placed beneath. In these cleansing vessels the beer remains till the
fermentation is completed; and it is then put into the store-vats, which
are casks or tuns of an immense size, where it is kept till wanted, and
is finally drawn off into barrels, and sent away from the brewery. The
store-vats are not represented in the figure: they are of a conical
shape, and of different dimensions, from fifteen to twenty feet
diameter, and usually from fifteen to twenty feet in depth. The
steam-engine which puts all the machine in motion is exhibited in its
place, on the left side of the figure. On the axis of the large
fly-wheel is a bevelled spur-wheel, which turns another similar wheel
upon the end of a horizontal shaft, which extends from the engine-house
to the great horse-wheel, set in motion by means of a spur-wheel. The
horse-wheel drives all the pinions for the mill-stones _b_, _b_, and
also the horizontal axis which works the three-barrelled pump _k_. The
rollers _a_, _a_, are turned by a bevel wheel upon the upper end of the
axis of the horse-wheel, which is prolonged for that purpose; and the
horizontal shaft H, for the mashing engine, is driven by a pair of bevel
wheels. There is likewise a sack-tackle, which is not represented. It is
a machine for drawing up the sacks of malt from the court-yard to the
highest part of the building, whence the sacks are wheeled on a truck to
the malt-loft A, and the contents of the sacks are discharged.

The horse-wheel is intended to be driven by horses occasionally, if the
steam-engine should fail; but these engines are now brought to such
perfection that it is very seldom any recourse of this kind is needed.

[Illustration: 104]

_Fig._ 104. is a representation of the _fermenting house_ at the brewery
of Messrs. Whitbread and Company, Chiswell Street, London, which is one
of the most complete in its arrangement in the world: it was erected
after the plan of Mr. Richardson, who conducts the brewing at those
works. The whole of _fig._ 104. is to be considered as devoted to the
same object as the large vessel M and the casks N, _fig._ 103. In _fig._
104., _r r_ is the pipe which leads from the different coolers to convey
the wort to the great fermenting vessels or squares M, of which there
are two, one behind the other; _f f_ represents a part of the great pipe
which conveys all the water from the well E, _fig._ 103, up to the water
cistern F. This pipe is conducted purposely up the wall of the
fermenting-house, _fig._ 104, and has a cock in it, near _r_, to stop
the passage. Just beneath this passage a branch-pipe _p_ proceeds, and
enters a large pipe _x x_, which has the former pipe _r_ withinside of
it. From the end of the pipe _x_, nearest to the squares M, another
branch _n n_ proceeds, and returns to the original pipe _f_, with a cock
to regulate it. The object of this arrangement is to make all, or any
part, of the cold water flow through the pipe _x x_, which surrounds the
pipe _r_, formed only of thin copper, and thus cool the wort passing
through the pipe _r_, until it is found by the thermometer to have the
exact temperature which is desirable before it is put to ferment in the
great square M. By means of the cocks at _n_ and _p_, the quantity of
cold water passing over the surface of the pipe _r_ can be regulated at
pleasure, whereby the heat of the wort, when it enters into the square,
may be adjusted within half a degree.

When the first fermentation in the squares M M is finished, the beer is
drawn off from them by pipes marked _c_, and conducted by its branches W
W W, to the different rows of fermenting-tuns, marked N N, which occupy
the greater part of the building. In the hollow between every two rows
are placed large troughs, to contain the yeast which they throw off. The
figure shows that the small tuns are all placed on a lower level than
the bottom of the great vessels M, so that the beer will flow into them,
and, by hydrostatic equilibrium, will fill them to the same level. When
they are filled, the communication-cock is shut; but, as the working off
the yeast diminishes the quantity of beer in each vessel, it is
necessary to replenish them from time to time. For this purpose, the two
large vats O O are filled from the great squares M M, before any beer is
drawn off into the small casks N, and this quantity of beer is reserved
at the higher level for filling up. The two vessels O O are, in reality,
situated between the two squares M M; but I have been obliged to place
them thus in the section, in order that they may be seen. Near each
filling-up tun O is a small cistern _t_ communicating with the tun O by
a pipe, which is closed by a float-valve. The small cisterns _t_ are
always in communication with the pipes which lead to the small
fermenting vessels N; and therefore the surface of the beer in all the
tuns, and in the cisterns, will always be at the same level; and as this
level subsides by the working off of the yeast from the tuns, the float
sinks and opens the valve, so as to admit a sufficiency of beer from the
filling-up tuns O, to restore the surfaces of the beer in all the tuns,
and also in the cistern _t_, to the original level. In order to carry
off the yeast which is produced by the fermentation of the beer in the
tuns O O, a conical iron dish or funnel is made to float upon the
surface of the beer which they contain; and from the centre of this
funnel a pipe, _o_, descends, and passes through the bottom of the tun,
being packed with a collar of leather, so as to be water-tight; at the
same time that it is at liberty to slide down, as the surface of the
beer descends in the tun. The yeast flows over the edge of this
funnel-shaped dish, and is conveyed down the pipe to a trough beneath.

Beneath the fermenting-house are large arched vaults, P, built with
stone, and lined with stucco. Into these the beer is let down in casks
when sufficiently fermented, and is kept in store till wanted. These
vaults are used at Mr. Whitbread’s brewery, instead of the great
store-vats of which we have before spoken, and are in some respects
preferable, because they preserve a great equality of temperature, being
beneath the surface of the earth.

The malt-rollers, or machines for bruising the grains of the malt,
_fig._ 101. 102., have been already described. The malt is shot down
from A, _fig._ 103., the malt-loft, into the hopper; and from this it is
let out gradually through a sluice or sliding shuttle, _a_, _fig._ 103.
and falls between the rollers.

[Illustration: 105]

_Fig._ 105. is the screw by which the ground or bruised malt is raised
up, or conveyed from one part of the brewery to another. K is an
inclined box or trough, in the centre of which the axis of the screw H
is placed; the spiral iron plate or worm, which is fixed projecting from
the axis, and which forms the screw, is made very nearly to fill the
inside of the box. By this means, when the screw is turned round by the
wheels E F, or by any other means, it raises up the malt from the box
_d_, and delivers it at the spout G.

This screw is equally applicable for conveying the malt horizontally in
the trough K, as slantingly; and similar machines are employed in
various parts of breweries for conveying the malt wherever the situation
of the works require.

[Illustration: 106]

_Fig._ 106. is the mashing-machine. _a a_ is the tun, made of wood
staves, hooped together. In the centre of it rises a perpendicular
shaft, _b_, which is turned slowly round by means of the bevelled wheels
_t u_ at the top. _c c_ are two arms, projecting from that axis, and
supporting the short vertical axis _d_ of the spur-wheel _x_, which is
turned by the spur-wheel _w_; so that, when the central axis _b_ is made
to revolve, it will carry the thick short axle _d_ round the tun in a
circle. That axle _d_ is furnished with a number of arms, _e e_, which
have blades placed obliquely to the plane of their motion. When the
axis is turned round, these arms agitate the malt in the tun, and give
it a constant tendency to rise upwards from the bottom.

The motion of the axle _d_ is produced by a wheel, _x_, on the upper end
of it, which is turned by a wheel, _w_, fastened on the middle of the
tube _b_, which turns freely round upon its central axis. Upon a higher
point of the same tube _b_ is a bevel wheel, _o_, receiving motion from
a bevel wheel, _q_, fixed upon the end of the horizontal axis _n n_,
which gives motion to the whole machine. This same axis has a pinion,
_p_, upon it, which gives motion to the wheel _r_, fixed near the middle
of a horizontal axle, which, at its left hand end, has a bevel pinion,
_t_, working the wheel _u_, before mentioned. By these means, the
rotation of the central axis _b_ will be very slow compared with the
motion of the axle _d_; for the latter will make seventeen or eighteen
revolutions on its own axis in the same space of time that it will be
carried once round the tun by the motion of the shaft _b_. At the
beginning of the operation of mashing, the machine is made to turn with
a slow motion; but, after having wetted all the malt by one revolution,
it is driven quicker. For this purpose, the ascending-shaft _f g_, which
gives motion to the machine, has two bevel wheels, _h i_, fixed upon a
tube, _f g_, which is fitted upon a central shaft. These wheels actuate
the wheels _m_ and _o_, upon the end of the horizontal shaft _n n_; but
the distance between the two wheels _h_ and _i_ is such, that they
cannot be engaged both at once with the wheels _m_ and _o_; but the tube
_f g_, to which they are fixed, is capable of sliding up and down on its
central axis sufficiently to bring either wheel _h_ or _i_ into geer
with its corresponding wheel _o_ or _m_, upon the horizontal shaft; and
as the diameters of _n o_, and _i m_, are of very different proportions,
the velocity of the motion of the machine can be varied at pleasure, by
using one or other. _k_ and _k_ are two levers, which are forked at
their extremities, and embrace collars at the ends of the tube _f g_.
These levers being united by a rod, _l_, the handle _k_ gives the means
of moving the tube _f g_, and its wheels _h i_, up or down, to throw
either the one or the other wheel into geer.

The object of boiling the wort is not merely evaporation and
concentration, but extraction, coagulation, and, finally, combination
with the hops; purposes which are better accomplished in a deep confined
copper, by a moderate heat, than in an open shallow pan with a quick
fire. The copper being encased above in brickwork, retains its digesting
temperature much longer than the pan could do. The waste steam of the
close kettle, moreover, can be economically employed in communicating
heat to water or weak worts; whereas the exhalations from an open pan
would prove a nuisance, and would need to be carried off by a hood. The
boiling has a four-fold effect: 1. it concentrates the wort; 2. during
the earlier stages of heating, it converts the starch into sugar,
dextrine, and gum, by means of the diastase; 3. it extracts the
substance of the hops diffused through the wort; 4. it coagulates the
albuminous matter present in the grain, or precipitates it by means of
the tannin of the hops.

The degree of evaporation is regulated by the nature of the wort, and
the quality of the beer. Strong ale and stout for keeping, require more
boiling than ordinary porter or table-beer brewed for immediate use. The
proportion of the water carried off by evaporation is usually from a
seventh to a sixth of the volume. The hops are introduced during the
progress of the ebullition. They serve to give the beer not only a
bitter aromatic taste, but also a keeping quality, or they counteract
its natural tendency to become sour; an effect partly due to the
precipitation of the albumen and starch, by their resinous and tanning
constituents, and partly to the antifermentable properties of their
lupuline, bitter principle, ethereous oil, and resin. In these respects,
there is none of the bitter plants which can be substituted for hops
with advantage. For strong beer, powerful fresh hops should be selected;
for weaker beer, an older and weaker article will suffice.

The hops are either boiled with the whole body of the wort, or extracted
with a portion of it; and this concentrated extract added to the rest.
The stronger the hops are, the longer time they require for extraction
of their virtues; for strong hops, an hour and a half or two hours
boiling may be proper; for a weaker sort, half an hour or an hour may be
sufficient; but it is never advisable to push this process too far, lest
a disagreeable bitterness, without aroma, be imparted to the beer. In
our breweries, it is the practice to boil the hops with a part of the
wort, and to filter the decoction through a drainer, called the _jack
hop-back_. The proportion of hops to malt is very various; but, in
general, from a pound and a quarter to a pound and a half of the former
are taken for 100 lbs. of the latter in making good table-beer. For
porter and strong ale, 2 pounds of hops are used, or even more; for
instance, one pound of hops to a bushel of malt, if the beer be destined
for the consumption of India.

During the boiling of the two ingredients, much coagulated albuminous
matter, in various states of combination, makes its appearance in the
liquid, constituting what is called the _breaking or curdling of the
wort_, when numerous minute flocks are seen floating in it. The
resinous, bitter, and oily-ethereous principles of the hops combine with
the sugar and gum, or dextrine of the wort; but for this effect they
require time and heat; showing that the boil is not a process of mere
evaporation, but one of chemical reaction. A yellowish-green pellicle of
hop-oil and resin appears upon the surface of the boiling wort, in a
somewhat frothy form: when this disappears, the boiling is presumed to
be completed, and the beer is strained off into the cooler. The
residuary hops may be pressed and used for an inferior quality of beer;
or they may be boiled with fresh wort, and be added to the next brewing
charge.

_Figs._ 107, 108. represent the copper of a London brewery. _Fig._ 107.
is a vertical section; _fig._ 108., a ground-plan of the fire-grate and
flue, upon a smaller scale: _a_ is the close copper kettle, having its
bottom convex within; _b_ is the open pan placed upon its top. From the
upper part of the copper, a wide tube, _c_, ascends, to carry off the
steam generated during the ebullition of the wort, which is conducted
through four downwards-slanting tubes, _d d_ (two only are visible in
this section), into the liquor of the pan _b_, in order to warm its
contents. A vertical iron shaft or spindle, _e_, passes down through the
tube _c_, nearly to the bottom of the copper, and is there mounted with
an iron arm, called _a rouser_, which carries round a chain hung in
loops, to prevent the hops from adhering to the bottom of the boiler.
Three bent stays, _f_, are stretched across the interior, to support the
shaft by a collet at their middle junction. The shaft carries at its
upper end a bevel wheel, _g_, working into a bevel pinion upon the axis
_h_, which may be turned either by power or by hand. The _rouser_ shaft
may be lifted by means of the chain _i_, which, going over two pulleys,
has its end passed round the wheel and axle _k_, and is turned by a
winch: _l_ is a tube for conveying the waste steam into the chimney _m_.

[Illustration: 107 108]

The heat is applied as follows:--For heating the colossal coppers of the
London breweries, two separate fires are required, which are separated
by a narrow wall of brickwork, _n_, _fig._ 107, 108. The dotted circle
_a´ a´_ indicates the largest circumference of the copper, and _b´ b´_
its bottom; _o o_ are the grates upon which the coals are thrown, not
through folding doors (as of old), but through a short slanting iron
hopper, shown at _p_, _fig._ 107., built in the wall, and kept
constantly filled with the fuel, in order to exclude the air. Thus the
lower stratum of coals gets ignited before it reaches the grate. Above
the hopper _p_, a narrow channel is provided for the admission of
atmospherical air, in such quantity merely as may be requisite to
complete the combustion of the smoke of the coals. Behind each grate
there is a fire-bridge, _r_, which reflects the flame upwards, and
causes it to play upon the bottom of the copper. The burnt air then
passes round the copper in a semicircular flue, _s s_, from which it
flows off into the chimney _m_, on whose under end a sliding
damper-plate, _t_, is placed, for tempering the draught. When cold air
is admitted at this orifice, the combustion of the fuel is immediately
checked. There is, besides, another slide-plate at the entrance of the
slanting flue into the vertical chimney, for regulating the play of the
flame under and around the copper. If the plate _t_ be opened, and the
other plate shut, the power of the fire is suspended, as it ought to be,
at the time of emptying the copper. Immediately over the grate is a
brick arch, _u_, to protect the front edge of the copper from the first
impulsion of the flame. The chimney is supported upon iron pillars, _v
v_; _w_ is a cavity closed with a slide-plate, through which the ashes
may be taken out from behind, by means of a long iron hook.

[Illustration: 109]

_Fig._ 109. represents one of the sluice-cocks, which are used to make
the communications of the pipes with the pumps, or other parts of the
brewery. B B represents the pipe in which the cock is placed. The two
parts of this pipe are screwed to the side of a box, C C, in which a
slider, A, rises and falls, and intercepts, at pleasure, the passage of
the pipe. The slider is moved by the rod _a_. This passes through a
stuffing-box, in the top of the box which contains the slider, and has
the rack _b_ fastened to it. The rack is moved by a pinion fixed upon
the axis of a handle _e_, and the rack and pinion are contained in a
frame _d_ which is supported by two pillars. The frame contains a small
roller behind the rack, which bears it up towards the pinion, and keeps
its teeth up to the teeth of the pinion. The slider A is made to fit
accurately against the internal surface of the box C, and to bear
against this surface by the pressure of a spring, so as to make a
perfectly close fitting.

[Illustration: 110]

_Fig._ 110. is a small cock to be placed in the side of the great store
vats, for the purpose of drawing off a small quantity of beer, to taste
and try its quality. A is a part of the stave or thickness of the great
store vat; into this the tube B of the cock is fitted, and is held tight
in its place by a nut, _a a_, screwed on withinside. At the other end of
the tube B, a plug, _c_, is fitted, by grinding it into a cone, and it
is kept in by a screw. This plug has a hole up the centre of it, and
from this a hole proceeds sidewise, and corresponds with a hole made
through the side of the tube when the cock is open; but when the plug
_c_ is turned round, the hole will not coincide, and then the cock will
be shut. D is the handle or key of the cock, by which its plug is turned
to open or shut it: this handle is put up the bore of the tube (the
cover E being first unscrewed and removed), and the end of it is adapted
to fit the end of the plug of the cock. The handle has a tube or passage
bored up it, to convey the beer away from the cock when it is opened,
and from this the passage _f_, through the handle, leads, to draw the
beer into a glass or tumbler. The hole in the side of the plug is so
arranged, that, when the handle is turned into a perpendicular
direction, with the passage _f_ downwards, the cock will be open. The
intention of this contrivance is, that there shall be no considerable
projection beyond the surface of the tun; because it sometimes happens
that a great hoop of the tun breaks, and, falling down, its great weight
would strike out any cock which had a projection; and, if this happened
in the night, much beer might be lost before it was discovered. The cock
above described, being almost wholly withinside, and having scarcely any
projection beyond the outside surface of the tun, is secure from this
accident.

[Illustration: 111]

_Fig._ 111. is a small contrivance of a vent peg, to be screwed into the
head of a common cask when the beer is to be drawn off from it, and it
is necessary to admit some air to allow the beer to flow. A A represents
a portion of the head of the cask into which the tube B is screwed. The
top of this tube is surrounded by a small cup, from which project the
two small handles C C, by which the peg is turned round to screw it into
the cask. The cup round the other part of the tube, is filled with
water; into this a small cup, D, is inverted; in consequence, the air
can gain admission into the cask when the pressure within is so far
diminished, that the air will bubble up through the water, and enter
beneath the small cup D.

The most efficient substance for fining beer hitherto discovered is
isinglass, which is prepared by solution in vinegar or old stale beer,
and this solution is afterwards reduced with thin mild beer generally
brewed for the purpose, in all large establishments, from a raw or
return wort. It must next be passed through a fine hair sieve, by means
of rubbing it down with a hard hair-brush, and brought to the proper
consistency by thin mild beer. If properly made, it will be clear,
transparent, and free from feculencies. Finings serve excellently to
remove any extraneous matter that may be found floating in the beer, and
thus changes it from bright to brilliant. The common quantity used is
from a pint to a quart per barrel, according to the nature of the beer.

To ascertain whether the beer is in a fit state for fining, put it into
a long glass cylindric vessel, and add to it a teaspoonful, or thereby,
of the fining; then give the mixture a good shake, by turning the vessel
up and down, after closing its mouth with the palm of the hand. If the
beer has been well brewed, its aptitude to become bright will be soon
shown by the mixture getting thick and curdy; a bright portion will
generally show itself at the bottom or middle; after which the finings
will gradually mount to the top, taking up all the impurities along with
them, till the whole becomes brilliant. Some have said that the finings
should carry the impurities down to the bottom; but this, according to
Mr. Black[8], takes place only with stubborn beer, which would not
become thoroughly bright with any quantity of finings which could be
introduced. Finings have usually a specific gravity of from 1·010 to
1·016, and, when added to beer in a fit condition for fining, invariably
go to the top, and not to the bottom. In fining beer in a barrel laid on
its side, if the finings do not make their appearance at the bung-hole,
the beer will not become bright. The isinglass must not be dissolved
with heat, nor in hot water.

  [8] Treatise on Brewing, 8vo, p. 68.

Beer brewed from imperfectly malted grain, or from a mixture of malt and
raw corn, gives a fermentation quite different in flavour from that of
beer from sound malt. The nose is, in fact, the best guide to the
experienced brewer for ascertaining whether his process is going on well
or ill.

Ropiness is a morbid state of beer, which is best remedied, according to
Mr. Black, by putting the beer into a vat with a false bottom, and
adding, per barrel, 4 or 5 pounds of hops, taken gradually away after
the first boilings of the worts; and to them may be added about half a
pound per barrel of mustard-seed. Rouse the beer as the hops are
gradually introduced, and, in some months, the ropiness will be
perfectly cured. The beer should be drawn off from below the false
bottom.

For theoretical views, see FERMENTATION; and for wort-cooling apparatus,
see REFRIGERATOR.


BEET-ROOT SUGAR. See SUGAR.


BELL-METAL, an alloy of copper and tin. See COPPER.


BELLOWS. See METALLURGY.


BEN OIL. See OIL OF BEN.


BENGAL STRIPES. Ginghams; a kind of cotton cloth woven with coloured
stripes.


BENJAMIN or BENZOIN. (_Benjoin_, Fr.; _Benzöe_, Germ.) A species of
resin used chiefly in perfumery. It is extracted by incision from the
trunk and branches of the _styrax benzoin_, which grows in Java,
Sumatra, Santa Fé, and in the kingdom of Siam. The plant belongs to the
decandria monogynia of Linnæus, and the natural family of the ebenaceæ.
It hardens readily in the air, and comes to us in brittle masses, whose
fracture presents a mixture of red, brown, and white grains of various
sizes, which, when white, and of a certain shape, have been called
_amygdaloid_, from their resemblance to almonds. The _sorted_ benzoin
is, on the other hand, very impure.

The fracture of benzoin is conchoidal, and its lustre greasy: its
specific gravity varies from 1·063 to 1·092. It has an agreeable smell,
somewhat like vanilla, which is most manifest when it is ground. It
enters into fusion at a gentle heat, and then exhales a white smoke,
which may be condensed into the acicular crystals of benzoic acid, of
which it contains 18 parts in the hundred. Stoltze recommends the
following process for extracting the acid. The resin is to be dissolved
in 3 parts of alcohol, the solution is to be introduced into a retort,
and a solution of carbonate of soda dissolved in dilute alcohol is to be
gradually added to it, till the free acid be neutralised; and then a
bulk of water equal to double the weight of the benzoin is to be poured
in. The alcohol being drawn off by distillation, the remaining liquor
contains the acid, and the resin floating upon it may be skimmed off and
washed, when its weight will be found to amount to about 80 per cent. of
the raw material. The benzoin contains traces of a volatile oil, and a
substance soluble in water, at least through the agency of carbonate of
potash. Ether does not dissolve benzoin completely. The fat and volatile
oils dissolve very little of it.

Unverdorben has found in benzoin, besides benzoic acid, and a little
volatile oil, no less than three different kinds of resin, none of which
has, however, been turned as yet to any use in the arts.

Benzoin is of great use in perfumery, as it enters into a number of
preparations; among which may be mentioned fumigating pastilles,
fumigating cloves (called also nails), _poudre à la maréchale_, &c. The
alcoholic tincture, mixed with water, forms _virginal_ milk. Benzoin
enters also into the composition of certain varnishes employed for
snuff-boxes and walkingsticks, in order to give these objects an
agreeable smell when they become heated in the hand. It is likewise
added to the spirituous solution of isinglass with which the best court
plaster is made.


BERLIN BLUE. Prussian blue. See BLUE.


BERRIES OF AVIGNON, _and Persian Berries_. (_Graines d’Avignon_, Fr.;
_Gelbbeeren_, Germ.) A yellowish dye-drug, the fruit of the _rhamnus
infectorius_, a plant cultivated in Provence, Languedoc, and Dauphiné,
for the sake of its berries, which are plucked before they are ripe,
while they have a greenish hue. Another variety comes from Persia,
whence its trivial name; it is larger than the French kind, and has
superior properties. The principal substances contained in these berries
are: 1. A colouring matter, which is united with a matter insoluble in
ether, little soluble in concentrated alcohol, and very soluble in
water: it appears to be volatile. 2. A matter remarkable for its
bitterness, which is soluble in water and alcohol. 3. A third principle,
in small quantity. A decoction of one part of the Avignon or Persian
berry in ten of water affords a brown-yellow liquor bordering upon
green, having the smell of a vegetable extract, and a slightly bitter
taste.

With gelatine that decoction gives, after some time, a slight
precipitate,--

  With alkalies                 a yellow hue,
   --   acids                   a slight muddiness,
   --   lime-water              a greenish-yellow tint,
   --   alum                    a yellow colour,
   --   red sulphate of iron    an olive-green colour,
   --   sulphate of copper      an olive colour,
   --   proto-muriate of tin    a greenish yellow with a slight
                                precipitate. (See CALICO PRINTING.)


BERYL. A beautiful mineral or gem, of moderate price, usually of a green
colour of various shades, passing into honey-yellow and sky blue.


BEZOAR. The name of certain concretions found in the stomachs of
animals, to which many fanciful virtues were formerly ascribed. They are
interesting only to the chemical pathologist.


BILE. (_Bile_, Fr.; _Galle_, Germ.) The secreted liquor of the liver in
animals. For an account of the uses of animal bile in the arts, see
GALL.


BIRDLIME. (_Glu_, Fr.; _Vogelleim_, Germ.) The best birdlime may be made
from the middle bark of the holly, boiled seven or eight hours in water,
till it is soft and tender, then laid by heaps in pits under ground,
covered with stones after the water is drained from it. There it must be
left during two or three weeks, to ferment in the summer season, and
watered, if necessary, till it passes into a mucilaginous state. It is
then to be pounded in a mortar to a paste, washed in running water, and
kneaded till it be free from extraneous matters. It is next left for
four or five days in earthen vessels to ferment and purify itself, when
it is fit for use. Birdlime may be made by the same process from the
mistletoe (_viburnum lantana_), young shoots of elder, and the barks of
other vegetables, as well as from most parasite plants.

Good birdlime is of a greenish colour, and sour flavour, somewhat
resembling that of linseed oil; gluey, stringy, and tenacious. By drying
in the air it becomes brittle, and may be powdered; but its viscosity
may be restored by moistening it. It has an acid reaction with litmus
paper. It contains resin, mucilage, a little free acid, colouring and
extractive matter. The resin has been called VISCINE.


BISMUTH. (_Bismuth_, Fr.; _Wismuth_, Germ.) Called also marcasite and
tin-glass. It was shown to be a metal somewhat different from lead, by
G. Agricola, in 1546; Stahl and Dufay proved its peculiarity; but it was
more minutely distinguished by Pott and Geoffroy, about the middle of
the last century. It is a rare substance, occurring native, as an oxide,
under the name of bismuth ochre; as a sulphuret, called bismuth glance;
as a sulphuret with copper, called copper bismuth ore; as also with
copper and lead, called needle ore. It is found associated likewise with
selenium and tellurium. The native metal occurs in various forms and
colours, as white, reddish, and variegated; in primitive and floetz
formations, along with the ores of cobalt, nickel, copper, silver, and
bismuth ochre; at the Saxon Erzgebirge, near Schneeberg, and Joh.
Georgenstadt; also in Bohemia, Baden, Wurtemberg, Hessia, Sweden,
Norway, England, and France.

The production of this metal is but a limited object of the
smelting-works of the Saxon Erzgebirge at Schneeberg. It there occurs,
mixed with cobalt speiss, in the proportion of about 7 per cent. upon
the average, and is procured by means of a peculiar furnace of
liquation, which is the most economical method, both as to saving fuel,
and oxidisement of the bismuth.

[Illustration: 112 113 114]

The bismuth eliquation furnace at Schneeberg is represented in _figs._
112, 113, and 114., of which the first is a view from above, the second
a view in front, and the third a transverse section in the dotted line A
B of _fig._ 112. _a_ is the ash-pit; _b_, the fireplace; _c_, the
eliquation pipes; _d_, the grate of masonry or brickwork, upon which the
fuel is thrown through the fire-door _e e_. The anterior deeper lying
orifice of the eliquation pipes is closed with the clay-plate _f_; which
has beneath a small circular groove, through which the liquefied metal
flows off. _g_ is a wall extending from the hearth-sole nearly to the
anterior orifices of the eliquation pipes, in which wall there are as
many fire-holes, _h_, as there are pipes in the furnace; _i_ are iron
pans, which receive the fluid metal; _h_, a wooden water-trough, in
which the bismuth is granulated and cooled; _l_, the posterior and
higher lying apertures of the eliquation pipes, shut merely with a
sheet-iron cover. The granulations of bismuth drained from the posterior
openings fall upon the flat surfaces _m_, and then into the
water-trough. _n n_ are draught-holes in the vault between the two
pipes, which serve for increasing or diminishing the heat at pleasure.

The ores to be eliquated (sweated) are sorted by hand from the gangue,
broken into pieces about the size of a hazel nut, and introduced into
the ignited pipes; one charge consisting of about 1/2 cwt.; so that the
pipes are filled to half their diameter, and three fourths of their
length. The sheet-iron door is shut, and the fire strongly urged,
whereby the bismuth begins to flow in ten minutes, and falls through the
holes in the clay-plates into hot pans containing some coal-dust.
Whenever it runs slowly, the ore is stirred round in the pipes, at
intervals during half an hour, in which time the liquation is usually
finished. The residuum, called bismuth barley (_graupen_), is scooped
out with iron rakes into a water trough; the pipes are charged afresh;
the pans, when full, have their contents cast into moulds, forming bars
of from 25 to 50 pounds weight. About 20 cwt. of ore are smelted in 8
hours, with a consumption of 63 Leipzic cubic feet of wood. The total
production of Schneeberg, in 1830, was 9800 lbs. The bismuth thus
procured by liquation upon the great scale, contains no small admixture
of arsenic, iron, and some other metals, from which it may be freed by
solution in nitric acid, precipitation by water, and reduction of the
subnitrated oxide by black flux. By exposing the crude bismuth for some
time to a dull red heat, under charcoal, arsenic is expelled.

Bismuth is white, and resembles antimony, but has a reddish tint;
whereas the latter metal has a bluish cast. It is brilliant,
crystallises readily in small cubical facets, is very brittle, and may
be easily reduced to powder. Its specific gravity is 9·83; and by
hammering it with care, the density may be increased to 9·8827. It melts
at 480° Fahr., and may be cooled 6 or 7 degrees below this point without
fixing; but the moment it begins to solidify, the temperature rises to
480°, and continues stationary till the whole mass is congealed. When
heated from 32° to 212°, it expands 1/710 in length. When pure it
affords a very valuable means of adjusting the scale of high-ranged
thermometers. At strong heats bismuth volatilises, may be distilled in
close vessels, and is thus obtained in crystalline laminæ.

The alloy of bismuth and lead in equal parts has a density of 10·709,
being greater than the mean of the constituents; it has a foliated
texture, is brittle, and of the same colour as bismuth. Bismuth, with
tin, forms a compound more elastic and sonorous than the tin itself, and
is therefore frequently added to it by the pewterers. With 1 of bismuth
and 24 of tin, the alloy is somewhat malleable; with more bismuth, it is
brittle. When much bismuth is present, it may be easily parted by strong
muriatic acid, which dissolves the tin, and leaves the bismuth in a
black powder. It has been said, that an alloy of tin, bismuth, nickel,
and silver, hinders iron from rusting. (_Erdmann’s Journal._) The alloy
of bismuth with tin and lead was first examined by Sir I. Newton, and
has been called ever since fusible metal. Eight parts of bismuth, 5 of
lead, and 3 of tin, melt at the moderate temperature of 202° F.; but 2
of bismuth, 1 of lead, and 1 of tin, melt at 200·75° F. according to
Rose. A small addition of mercury of course aids the fusibility. Such
alloys serve to take casts of anatomical preparations. An alloy of 1
bismuth, 2 tin, and 1 lead, is employed as a soft solder by the
pewterers; and the same has been proposed as a bath for tempering steel
instruments. Cake-moulds, for the manufacturers of toilet soaps are made
of the same metal; as also excellent clichés for stereotype, of 3 lead,
2 tin, and 5 bismuth; an alloy which melts at 199° F. This compound
should be allowed to cool upon a piece of pasteboard, till it becomes of
a doughy consistence, before it is applied to the mould, to receive the
impress of the stamp.

The employment of plates of fusible metal as safety _rondelles_, to
apertures in the tops of steam boilers has been proposed in France,
because they would melt and give way at elevations of temperature under
those which would endanger the bursting of the vessel; the fusibility of
the alloy being proportioned to the quality of steam required for the
engine. It has been found, however, that boilers, apparently secured in
this way, burst, while the safety discs remained entire; the expansive
force of the steam causing explosion so suddenly, that the fusible alloy
had not time to melt or give way.

There are two, perhaps three, oxides of bismuth; the first and the
third, or the suboxide and super-oxide, are merely objects of chemical
curiosity. The oxide proper occurs native, and may be readily formed by
exposing the metal to a red-white heat in a muffle, when it takes fire,
burns with a faint blue flame, and sends off fumes which condense into a
yellow pulverulent oxide. But an easier process than that now mentioned
is to dissolve the bismuth in nitric acid, precipitate with water, and
expose the precipitate to a red heat. The oxide thus obtained has a
straw yellow colour, and fuses at a high heat into an opaque glass of a
dark-brown or black colour; but which becomes less opaque and yellow
after it has cooled. Its specific gravity is so high as 8·211. It
consists of 89·87 of metal and 10·13 oxygen in 100 parts. The above
precipitate, which is a sub-nitrate of bismuth, is called _pearl-white_,
and is employed as a flux for certain enamels; as it augments their
fusibility without imparting any colour to them. Hence, it is used
sometimes as a vehicle of the colours of other metallic oxides. When
well washed, it is employed in gilding porcelain; being added in the
proportion of one fifteenth to the gold. But pearl-white is most used by
ladies, as a cosmetic for giving a brilliant tint to a faded complexion.
It is called _blanc de fard_, by the French. If it contains, as bismuth
often does, a little silver, it becomes grey or dingy coloured on
exposure to light. When the oxide is prepared, by dropping the nitric
solution into an alkaline lye in excess, if this precipitate is well
washed and dried, it forms an excellent medicine; and is given, mixed
with gum tragacanth, for the relief of cardialgia, or burning and
spasmodic pains of the stomach.

Another sort of pearl-powder is prepared by adding a very dilute
solution of common salt to the above nitric solution of bismuth, whereby
a pulverulent sub-chloride of the metal is obtained in a light
flocculent form. A similar powder of a mother-of-pearl aspect may be
formed by dropping dilute muriatic acid into the solution of nitrate of
bismuth. The arsenic always present in the bismuth of commerce is
converted by nitric acid into arsenic acid, which, forming an insoluble
arseniate of bismuth, separates from the solution, unless there be such
an excess of nitric acid as to re-dissolve it. Hence the medicinal
oxide, prepared from a rightly-made nitrate, can contain no arsenic. If
we write with a pen dipped in that solution, the dry invisible traces
will become legible on plunging the paper in water.

It has been proposed to substitute bismuth for lead in assaying silver,
as a smaller quantity of it answers the purpose, and, as its oxide is
more fluent, can therefore penetrate the cupel more readily, and give a
more rapid result. But, independently of the objection from its high
price, bismuth has the disadvantage of boiling up, as well as of
_rocking_ or vegetating, with the silver, when the cupellation requires
a high heat. In extracting the silver from the galena found in the
copper-mine of Yahlun, it has happened sometimes that the silver
concreted towards the end of the operation, and produced a cauliflower
excrescence, which had to be cupelled again with a fresh dose of lead.
It was observed that, in this case, a portion of the silver had passed
into the cupel. Berzelius detected in a sample of silver thus concreted
the presence of bismuth.

The nitrate of bismuth, mixed with solution of tin and tartar, has been
employed as a mordant for dyeing lilac and violet in calico printing.


BISTRE. (_Bistre_, Fr. _bister_, Germ.) A brown colour which is used in
water colours, in the same way as China ink. It is prepared from
wood-soot, that of beech being preferred. The most compact and best
burned parcels of soot are collected from the chimney, pulverised, and
passed through a silk sieve. This powder is infused in pure water, and
stirred frequently with a glass ruler, then allowed to settle when the
water is decanted. If the salts are not all washed away, the process may
be repeated with warm water. The paste is now to be poured into a long
narrow vessel filled with water, stirred well, and left to settle for a
few minutes, in order to let the grosser parts subside. The supernatant
part is then to be poured off into a similar vessel. This process may be
repeated twice or thrice, to obtain a very good bistre. At last the
settled deposit is sufficiently fine, and, when freed from its
supernatant water, it is mixed with gum-water, moulded into proper
cakes, and dried. It is not used in oil painting, but has the same
effect in water-colours as brown pink has in oil.


BITUMEN, or ASPHALTUM. (_Bitume_, Fr. _Erdpech_, Germ.) A black
substance found in the earth, externally not dissimilar to pit-coal. It
is composed of carbon, hydrogen, and oxygen, like organic bodies; but
its origin is unknown. It has not been observed among the primitive or
older strata, but only in the secondary and alluvial formations. It
constitutes sometimes considerable beds, as in the isle of Trinidad,
where it occurs over an extensive district, in scattered masses. The
greater part of the asphaltum to be met with in commerce comes from the
Dead Sea, on whose shores it is cast up and gathered; whence it has got
the name of Jewish bitumen. In its black colour and fracture it
resembles ordinary pitch. By friction it affords negative electricity.
Its average density is 1·16. It melts at the temperature of boiling
water, kindles very readily at the flame, burns brightly with a thick
smoke, and leaves little ashes. Distilled by itself, it yields a
peculiar bituminous oil, very little water, some combustible gases, and
traces of ammonia. It leaves about one third of its weight of charcoal
after combustion, and ashes, containing silica, alumina, oxide of iron,
sometimes a little lime, and oxide of manganese. According to John,
asphaltum may be decomposed, by different solvents, into three distinct
substances. Water dissolves nothing; alcohol (anhydrous) dissolves out a
yellow resin equal to 5 per cent. of the weight of the asphaltum; that
resin is soluble in dilute alcohol and in ether. The portion not soluble
in the alcohol gives up a brown resin to ether, amounting to 70 per
cent. of the weight of the asphaltum. On evaporating off the ether, the
resin remains of a brownish-black colour, which dissolves readily in the
volatile oils and in the oil of petroleum. The portion of asphaltum
which does not dissolve in ether is very soluble in oil of turpentine,
and in oil of petroleum; but less so in oil of lavender. These three
resinous principles dissolve all together by digestion in the oils of
anise, rosemary, turpentine, olive, hemp-seed, nut, and linseed. Caustic
potash dissolves a notable quantity of asphaltum; but carbonate of
potash has no effect upon it.

Asphaltum enters into the composition of hydraulic cements, and into
that of black varnishes, called japans, for coating iron trays, &c. A
similar varnish may be prepared by dissolving 12 parts of fused amber, 2
parts of rosin, and 2 parts of asphaltum, in 6 parts of linseed oil
varnish, to which 12 parts of oil of turpentine have been added.

There is a kind of bitumen found at Aniches, in France, in the
department of the north, which is black, very fusible, and soft. It
burns with flame. Alcohol, ether, and oil of turpentine extract from it
a fatty substance, which may be saponified with alkalis.

The bitumen of Murindò, near Choco, in Columbia, is of a brownish-black
colour, soft, and has an earthy fracture. It has an acrid taste, burns
with a smell of vanilla, and is said to contain a large quantity of
benzoic acid. It appears to be the result of the decomposition of trees
containing benzoin.

Asphaltum occurs abundantly at the surface of the salt lake Asphaltites,
in Judea, produced from springs in the neighbourhood; it is floated
down, gathers consistence, and accumulates upon the surface of the lake;
the winds drive it on the shores, and the inhabitants collect it for
sale. Its inspissation diffuses a disagreeable smell in the air of that
region, which is supposed by the natives to be powerful enough to kill
birds when they attempt to fly across the lake.

But probably the most remarkable locality of asphaltum in the world is
the entire basin, or rather plain of it, in the island of Trinidad,
called the Tar Lake. It lies on the highest land in the island, and
emits a strong smell, sensible at ten miles’ distance. Its first
appearance is that of a lake of water, but, when viewed more nearly, it
seems to be a surface of glass. In hot weather its surface liquifies to
the depth of an inch, and it cannot then be walked upon. It is of a
circular form, about three miles in circumference, and of a depth not
ascertained. Large fissures frequently open and close up in it, whence
the pitch has been supposed to float upon a body of water. The soil, for
a considerable distance round it, consists of cinders and burnt earth,
and presents in many points indications of convulsions by subterranean
fire. In several parts of the neighbouring woods, there are round holes
and fissures in the ground, containing liquid bitumen to the depth of
two inches.

Mr. Hatchett examined some specimens from Trinidad, and concluded that
what had been heretofore supposed to be a pure mineral pitch was in
reality only a porous stone of the argillaceous kind, much impregnated
with bitumen.

These various bitumens belong exclusively to the secondary and tertiary
geological formations, and are not found among primitive rocks, except
very rarely in veins. They occur most generally in calcareous,
argillaceous, and sandy strata, and also in volcanic districts.
Petroleum frequently floats on the waters which issue from the volcanic
mountains, or which lie at their base; even the sea is at times covered
with it near the volcanic islands of Cape Verd. Mr. Breislak observed a
petroleum spring rising from the bottom of the sea near the southern
base of Vesuvius.

The substance with which bitumen seems to have the most constant and
most remarkable relations, is sea-salt; so that almost all the countries
most abundant in petroleum, as Italy, Transylvania, Persia, the environs
of Babylon, the region of the Dead Sea, &c., contain salt mines, or
lakes, or exhibit saline efflorescences. Iron pyrites is often
impregnated with petroleum, or contains a bituminous nucleus.

The origin of bitumen is as little known as that of most of the
productions of nature. Some regard it as an empyreumatic oil, a matter
analogous to liquid resin or essential oil, resulting from the
destruction of that astonishing multitude of animals and vegetables
buried in the earth, whose solid remains are daily brought to view in
mineral researches. It has been also supposed that naphtha and petroleum
are the product of coals decomposed either by the fire of volcanos, by
the subterranean combustion of coal itself, or by the decomposition of
pyrites. The latter opinion is not supported by any direct evidence, but
the two former are sufficiently probable.

_Elastic Bitumen_ is a rare substance, found hitherto only near
Castleton, in Derbyshire, in fissures of slaty clay.

_Bituminous mastic, or cement_, has been of late extensively employed in
France for covering roofs and terraces, and lining water cisterns. The
mineral bitumen used for the composition of this mastic is procured
chiefly from the _Obsann_ (Bas-Rhin), from the Parc (department de
l’Ain), and from the _Puy-de-la-Poix_ (department of Puy-de-Dome). But
boiled coal-tar answers equally well. In the neighbourhood of these
localities, there is a limestone impregnated with bitumen, which suits
for giving consistence to the cement. This is well dried, ground to
powder, sifted, and stirred while hot, in about one fifth its weight of
melted asphaltum, contained in a cast-iron boiler. Dry chalk or bricks,
ground and sifted, will suit equally well. As soon as this paste is made
quite homogeneous, it is lifted out with an iron shovel or spoon, and
spread in rectangular moulds, secured with pegs at the joints, fastened
to a kind of platform of smoothed planks, covered with strong
sheet-iron. The sides of these moulds should be previously smeared over
with a thin coat of loam-paste, to prevent their adhesion to the mastic.
Whenever the cake is cold, the frame is taken asunder, and it is removed
from the iron plate by an oblong shovel, or strong spatula of iron.
These cakes or bricks are usually 18 inches long, 12 broad, and 4 thick,
and weigh about 70 lbs.


BITTER PRINCIPLE. (_Amère_, Fr.; _Bitterstoff_, Germ.) This principle
has not been insulated hitherto by the chemist from the other proximate
principles of plants, but its existence is sufficiently recognised by
the taste. The following list contains the principal bitter substances,
many of which have been used in the arts and in medicine.

  +--------------+-----------------+------------------+--------------+
  |Name.         |Part employed.   |Country.          |Observations. |
  +--------------+-----------------+------------------+--------------+
  |Quassia       |Wood             |Surinam, E. Indies|Powerfully    |
  |              |                 |                  |bitter        |
  |Wormwood      |Herb             |Great Britain     |Ditto         |
  |Aloe          |Inspissated juice|South Africa      |Ditto         |
  |Angustura     |Bark             |South America     |Ditto         |
  |Orange        |Unripe fruit     |South of Europe } |Aromatic      |
  |Ditto         |Peel             |Ditto           } |bitter        |
  |Acorus        |Root             |Ditto             |Ditto         |
  |Carduus Bene- |Herb             |Greek Archipelago |              |
  |dictus        |                 |                  |              |
  |Cascarilla    |Bark             |Jamaica           |Ditto         |
  |Centaury      |Herb             |Great Britain     |              |
  |Camomile      |Flowers          |                  |              |
  |Colocynth     |Fruit            |Levant            |Intolerably   |
  |              |                 |                  |bitter        |
  |Colombo       |Root             |East Africa       |Very bitter   |
  |Fumitory      |Herb             |Great Britain     |              |
  |Gentiana lutea|Root             |Switzerland       |Very bitter   |
  |Ground Ivy    |Herb             |Great Britain     |              |
  |Walnut        |Peels            |                  |With tannin   |
  |Island moss   |                 |                  |With starch   |
  |Hops          |Scales of the    |Great Britain     |Aromatic      |
  |              |female flowers   |                  |bitters       |
  |Milfoil       |Herb flowers     |Great Britain     |              |
  |Large-leaved  |Herb             |Great Britain     |              |
  |Satyrion      |                 |                  |              |
  |Rhubarb       |Root             |China             |Disagreeable  |
  |              |                 |                  |odour         |
  |Rue           |Herb             |Great Britain     |Bitter and    |
  |              |                 |                  |sharp         |
  |Tansy         |Herb flowers     |Ditto             |Bitter and    |
  |              |                 |                  |offensive     |
  |Bitter trefoil|Herb             |Ditto             |              |
  |Simarouba     |Bark             |Guyana            |              |
  |Bryony        |Root             |Great Britain     |Sharp, bitter,|
  |              |                 |                  |nauseous      |
  |Coffee        |Seeds            |Arabia            |              |
  +--------------+-----------------+------------------+--------------+


BLACK DYE. (_Teinte noire_, Fr. _Schwartze farbe_, Germ.) For 1 cwt. of
cloth, there are put into a boiler of middle size 18 lbs. of logwood,
with as much Aleppo galls in powder, and the whole, being enclosed in a
bag, is boiled in a sufficient quantity of water for 12 hours. One-third
of this bath is transferred into another boiler with two pounds of
verdigris; and the stuff is passed through this solution, stirring it
continually during two hours, taking care to keep the bath very hot
without boiling. The stuff is then lifted out, another third of the bath
is added to the boiler, along with eight pounds of sulphate of iron or
green vitriol. The fire is to be lowered while the sulphate dissolves,
and the bath is allowed to cool for half an hour, after which the stuff
is introduced, and well moved about for an hour, after which it is taken
out to air. Lastly, the remaining third of the bath is added to the
other two, taking care to squeeze the bag well. 18 or 22 lbs. of sumach
are thrown in; the whole is just brought to a boil, and then refreshed
with a little cold water; two pounds more of sulphate of iron are added,
after which the stuff is turned through for an hour. It is thereafter
washed, aired, and put again into the bath, stirring it continually for
an hour. After this, it is carried to the river, washed well, and then
filled. Whenever the water runs off clear, a bath is prepared with weld,
which is made to boil for an instant; and after refreshing the bath the
stuff is turned in to soften, and to render the black more fast. In this
manner, a very beautiful black is obtained, without rendering the cloth
too harsh.

Commonly more simple processes are employed. Thus the blue cloth is
simply turned through a bath of gall-nuts, where it is boiled for two
hours. It is next passed through a bath of logwood and sulphate of iron
for two hours, without boiling, after which it is washed and fulled.

Hellot has found that the dyeing might be performed in the following
manner:--For 20 yards of dark blue-cloth, a bath is made of two pounds
of fustic (morus tinctoria), 4-1/4 lbs. of logwood, and 11 lbs. sumach.
After boiling the cloth in it for three hours it is lifted out, 11 lbs.
of sulphate of iron are thrown into the boiler, and the cloth is then
passed through it during two hours. It is now aired, and put again in
the bath for an hour. It is, lastly, washed and scoured. The black is
less velvety than that of the preceding process. Experience convinced
him that the maddering prescribed in the ancient regulations only gives
a reddish cast to the black, which is obtained finer and more velvety
without madder.

A black may be dyed likewise without having given a blue ground. This
method is employed for cloths of little value. In this case they are
rooted; that is to say, they receive a dun ground with walnut husks, or
the root of the walnut tree, and are afterwards made black in the manner
above described, or in some other way; for it is obvious that a black
may be obtained by several processes.

According to Lewis, the proportions which the English dyers most
generally adopt are, for one hundred and twelve pounds of woollen cloth
previously dyed of a dark blue, about five pounds of sulphate of iron,
as much gall-nuts, and thirty pounds of logwood. They begin by galling
the cloth, they then pass it through the decoction of logwood, to which
the sulphate of iron has been added.

When the cloth is completely dyed, it is washed in the river, and passed
through the fulling-mill till the water runs off clear and colourless.
Some persons recommend, for fine cloths, to full them with soap water.
This operation requires an expert workman, who can free the cloth
thoroughly from the soap. Several recommend at its coming from the
fulling to pass the cloth through a bath of weld, with the view of
giving softness and solidity to the black. Lewis says, that passing the
cloth through weld, after it has been treated with soap, is absolutely
useless, although it may be beneficial when this operation has been
neglected.

Different operations may be distinguished in dyeing _silk_ black; the
boiling of the silk, its galling, the preparation of the bath, the
operation of dyeing, the softening of the black.

Silk naturally contains a substance called gum, which gives it the
stiffness and elasticity peculiar to it in its native state; but this
adds nothing to the strength of the silk, which is then styled raw; it
rather renders it, indeed, more apt to wear out by the stiffness which
it communicates; and although raw silk more readily takes a black
colour, yet the black is not so perfect in intensity, nor does it so
well resist the re-agents capable of dissolving the colouring particles,
as silk, which is scoured or deprived of its gum.

To cleanse silk intended for black, it is usually boiled four or five
hours with one fifth of its weight of white soap, after which it is
carefully beetled and washed.

For the galling, nut-galls equal nearly to three fourths of the weight
of the silk are boiled during three or four hours; but on account of the
price of Aleppo galls, more or less of the white gall-nuts, or of even
an inferior kind called galon, berry or apple galls, are used. The
proportion commonly employed at Paris is two parts of Aleppo galls to
from eight to ten parts of galon. After the boiling, the galls are
allowed to settle for about two hours. The silk is then plunged into the
bath, and left in it from twelve to thirty-six hours, after which it is
taken out and washed in the river.

Silk is capable of combining with quantities, more or less considerable,
of the astringent principle; whence results a considerable increase of
weight, not only from the weight of the astringent principle, but also
from that of the colouring particles, which subsequently fix themselves
in proportion to the quantity of the astringent principle which had
entered into combination. Consequently, the processes are varied
according to the degree of weight which it is wished to communicate to
the silk; a circumstance requiring some illustration.

The commerce of silk goods is carried on in two ways; they are sold
either by the weight, or by the surface, that is, by measure. Thus the
trade of Tours was formerly distinguished from that of Lyons; the silks
of the former being sold by weight, those of the latter, by measure. It
was therefore their interest to surcharge the weight at Tours, and, on
the contrary, to be sparing of the dyeing ingredients at Lyons; whence
came the distinction of light black and heavy black. At present, both
methods of dyeing are practised at Lyons, the two modes of sale having
been adopted there.

Silk loses nearly a fourth of its weight by a thorough boiling, and it
resumes, in the light black dye, one half of this loss; but in the heavy
black dye, it takes sometimes upwards of a fifth more than its primitive
weight; a surcharge injurious to the beauty of the black, and the
durability of the stuff. The surcharged kind is denominated English
black, because it is pretended that it was first practised in England.
Since silk dyed with a great surcharge has not a beautiful black, it is
usually destined for weft, and is blended with a warp dyed of a fine
black.

The peculiarity of the process for obtaining the heavy black consists in
leaving the silk longer in the gall liquor, in repeating the galling, in
passing the silk a greater number of times through the dye, and even
letting it lie in it for some time. The first galling is usually made
with galls which have served for a preceding operation, and fresh
gall-nuts are employed for the second. But these methods would not be
sufficient for giving a great surcharge, such as is found in what is
called the English black. To give it this weight, the silk is galled
without being ungummed; and, on coming out of the galls, it is rendered
supple by being worked on the jack and pin.

The silk-dyers keep a black vat, and its very complex composition varies
in different dye-houses. These vats are commonly established for many
years; and when their black dye is exhausted it is renovated by what is
called in France a _brevet_. When the deposit which has accumulated in
it is too great, it is taken out, so that at the end of a certain time
nothing remains of the several ingredients which composed the primitive
bath, but which are not employed in the brevet.

For the dyeing of raw silk black, it is galled in the cold, with the
bath of galls which has already served for the black of boiled silk. For
this purpose, silk, in its native yellow colour, is made choice of. It
should be remarked, that when it is desired to preserve a portion of the
gum of the silk, which is afterwards made flexible, the galling is given
with the hot bath of gall-nuts in the ordinary manner. But here, where
the whole gum of the silk, and its concomitant elasticity, are to be
preserved, the galling is made in the cold. If the infusion of galls be
weak, the silk is left in it for several days.

Silk thus prepared and washed takes very easily the black dye, and the
rinsing in a little water, to which sulphate of iron may be added, is
sufficient to give it. The dye is made in the cold; but, according to
the greater or less strength of the rinsings, it requires more or less
time. Occasionally three or four days are necessary; after which it is
washed, it is beetled once or twice, and it is then dried without
wringing, to avoid softening it.

Raw silk may be more quickly dyed, by shaking it round the rods in the
cold bath after the galling, airing it, and repeating these
manipulations several times, after which it is washed and dried as
above.

Macquer describes a more simple process for the black by which velvet is
dyed at Genoa; and he says that this process, rendered still simpler,
has had complete success at Tours. The following is his description.

For 1 cwt. (50 kilogrammes) silk, (22 lbs. 11 kilogrammes) of Aleppo
galls, in powder, are boiled for an hour in a sufficient quantity of
water. The bath is allowed to settle till the galls have fallen to the
bottom of the boiler, from which they are withdrawn; after which 32 lbs.
of English vitriol (or copperas) are introduced, with 13 lbs. of iron
filings, and 22 lbs. of country gum, put into a kind of two-handled
cullender, pierced every where with holes. This kettle is suspended by
two rods in the boiler, so as not to reach the bottom. The gum is left
to dissolve for about an hour, stirring it from time to time. If, after
this time, some gum remains in the kettle, it is a proof that the bath,
which contains two hogsheads, has taken as much of it as is necessary.
If, on the contrary, the whole gum is dissolved, from one to 4 lbs. more
may be added. This cullender is left constantly suspended in the boiler,
from which it is removed only when the dyeing is going on; and
thereafter it is replaced. During all these operations the boiler must
be kept hot, but without boiling. The galling of the silk is performed
with one third of Aleppo galls. The silk is left in it for six hours
the first time, then for twelve hours. The rest, _secundum artem_.

Lewis states that he has repeated this process in the small way; and
that, by adding sulphate of iron progressively, and repeating the
immersions of the silk a great number of times, he eventually obtained a
fine black.

Astringents differ from one another as to the quantity of the principle
which enters into combination with the oxide of iron. Hence, the
proportion of the sulphate, or of any other salt of iron, and that of
the astringents, should vary according to the astringents made use of,
and according to their respective quantities. Gall-nut is the substance
which contains most astringent; sumach, which seems second to it in this
respect, throws down (decomposes), however, only half as much sulphate
of iron.

The most suitable proportion of sulphate of iron appears to be that
which corresponds to the quantity of the astringent matter, so that the
whole iron precipitable by the astringent may be thrown down, and the
whole astringent may be taken up in combination with the iron. As it is
not possible, however, to arrive at such precision, it is better that
the sulphate of iron should predominate, because the astringent, when in
excess, counteracts the precipitation of the black colouring particles,
and has the property of even dissolving them.

This action of the astringent is such that, if a pattern of black cloth
be boiled with gall-nuts, it is reducible to grey. An observation of
Lewis may thence be explained. If cloth be turned several times through
the colouring bath, after it has taken a good black colour, instead of
acquiring more body, it is weakened, and becomes brownish. Too
considerable a quantity of the ingredients produces the same effect; to
which the sulphuric acid, set at liberty by the precipitation of the
oxide of iron, contributes.

It is merely the highly oxidised sulphate which is decomposed by the
astringent; whence it appears, that the sulphate will produce a
different effect according to its state of oxidisement, and call for
other proportions. Some advise, therefore, to follow the method of
Proust, employing it in the oxidised state; but in this case it is only
partially decomposed, and another part is brought, by the action of the
astringent, into the lower degree of oxidisement.

The particles precipitated by the mixture of an astringent and sulphate
of iron have not at first a deep colour; but they pass to a black by
contact of air while they are moist.

Under _dyeing_ I shall show that the black dye is only a very condensed
colour, and that it assumes more intensity from the mixture of different
colours likewise deep. It is for this reason advantageous to unite
several astringents, each combination of which produces a different
shade. But blue appears the colour most conducive to this effect, and it
corrects the tendency to dun, which is remarked in the black produced on
stuffs by the other astringents.

On this property is founded the practice of giving a blue ground to
black cloths, which acquire more beauty and solidity the deeper the
blue. Another advantage of this practice is to diminish the quantity of
sulphuric acid which is necessarily disengaged by the precipitation of
the black particles, and which would not only counteract their fixation,
but would further weaken the stuff, and give it harshness.

For common stuffs, a portion of the effect of the blue ground is
produced by the rooting.

The mixture of logwood with astringents contributes to the beauty of the
black in a twofold way. It produces molecules of a hue different from
what the astringents do, and particularly blue molecules, with the oxide
of copper, commonly employed in the black dyes; which appears to be more
useful the more acetate the verdigris made use of contains.

The boil of weld, by which the dye of black cloth is frequently
finished, may also contribute to its beauty, by the shade peculiar to
its combination. It has, moreover, the advantage of giving softness to
the stuffs.

The processes that are employed for wool, yield, according to the
observation of Lewis, only a rusty black to silk; and cotton is hardly
dyed by the processes proper for wool and silk. Let us endeavour to
ascertain the conditions which these three varieties of dyeing demand.

Wool has a great tendency to combine with colouring substances; but its
physical nature requires its combinations to be made in general at a
high temperature. The combination of the black molecules may therefore
be directly effected in a bath, in proportion as they form; and, if the
operation be prolonged by subdividing it, it is only with the view of
changing the necessary oxidisement of the sulphate, and augmenting that
of the colouring particles themselves.

Silk has little disposition to unite with the black particles. It seems
to be merely by the agency of the tannin, with which it is previously
impregnated, that these particles can fix themselves on it, especially
after it has been scoured. For this reason, silk baths should be old,
and have the colouring particles accumulated in them, but so feebly
suspended as to yield to a weak affinity. Their precipitation is
counteracted by the addition of gum, or other mucilaginous substances.
The obstacle which might arise from the sulphuric acid set at liberty is
destroyed by iron filings, or other basis. Thus, baths of a very
different composition, but with the essential condition of age, may be
proper for this dye. For cotton black dye, see CALICO PRINTING.


BLACK PIGMENT. The finest light black is prepared principally for the
manufacturing of printers’ ink. In Messrs. Martin and Grafton’s patent
process, the black is obtained by burning common coal-tar, which should,
however, be previously divested, as much as possible, of the ammoniacal
liquor and acid mixed with it in the tank.

For this purpose, it is proposed that four casks should be employed,
each capable of holding 130 gallons, and into every one of them are to
be put about 60 gallons of the rough impure tar, to which an equal
quantity of lime-water is to be added, and then agitated by machinery or
manual labour until the lime-water is completely mixed with the tar. The
vessels should next be suffered to rest for about six hours, by which
time the tar will settle at the bottom of the casks, and the water may
be drawn off. The casks containing the tar should now be filled with hot
water, which may be supplied from the boiler of a steam engine, and the
whole again agitated as before. This process may be repeated three
times, suffering the tar to subside between each; and twelve hours
should be allowed for settling from the last water, so that the whole of
the tar and water may become separated, the water rising to the top of
the cask, and the tar being left at the bottom in a pure state.

But, as some of the water will yet remain mechanically combined with the
tar, it is proposed that the tar should be subjected to the process of
distillation. For this purpose, a still, capable of holding 120 gallons,
may be employed, in which about 50 gallons, at one time, may be operated
upon; when, by a gentle heat, the water, and other impurities which the
tar may have retained, will be driven off. As soon as the water appears
to have evaporated, and the spirit runs fine and clear, the process of
distillation should be stopped; and, when cold, the pure tar may be
drawn off, and set apart for the purpose of being employed as
contemplated in the patent.

The tar thus purified may be now converted into black, or it may be
subjected to further rectification to divest it of the mineral pitch, or
asphaltum, which is combined with the oil and spirit: the latter is to
be preferred, because the mineral pitch, or asphaltum, is only
inflammable at a high temperature, which renders it more troublesome to
use in the process here contemplated, and also would cause the apparatus
to require frequent cleaning from the carbonized pitch deposited. In
order, therefore, to get rid of the mineral pitch, or asphaltum, forty
gallons of the tar are to be introduced into a still, as before; and,
instead of stopping the operation, as soon as the spirit begins to come
over, the distillation is continued with a strong heat, so as to force
over the whole of the oil and spirit, leaving the residuum of asphaltum
in the still: this process, however, is known to every chemist, and need
not be further explained.

[Illustration: 115 116]

In _fig._ 115. is exhibited a rude representation of the apparatus
employed in preparing and collecting the fine light spirit black,
produced by the combustion of the oil and spirit of coal-tar, after it
has been purified as above described. _a_ is the brickwork which
supports a number of burners issuing from a tube, _b_, within, and here
shown by dots, as passing along its whole length. _Fig._ 116. is a
section of the brickwork, with the tube, burner, and receiver, as will
be described hereafter. The tube may be called the tar main, as it is
intended to be filled with tar: it is constructed of cast iron, and from
it issue several (in this figure twenty-four) jets or burners, _c_, _c_,
_c_; any other number may be employed. _d_ is a furnace under the tar
main, the flue of which extends along, for the purpose of heating the
tar to the boiling point, in order to facilitate the process. From the
main, _b_, the tar flows into the jets _c_; wicks are introduced into
the jets, and, when set fire to by a red-hot stick, will burn and emit a
very considerable quantity of smoke; which it is the object of this
apparatus to conduct through many passages, for the purpose of
collecting its sooty particles.

There are a number of hoods, _e_, _e_, _e_, or bonnets, as they are
termed, all of which, through their pipes, have communication with, or
lead into, a main chimney, _f_, _f_. Into these hoods or bonnets the
smoke of the burners ascends, and from thence passes into the main
chimney _f_, and thence through the smoke tubes into the box _g_: here
the heaviest particles of the black deposit themselves; but, as the
smoke passes on through the farther pipes, a deposit of the second, or
finer, particles of black takes place in the box _h_. From hence the
smoke proceeds through other pipes into a series of canvass bags, _i_,
_i_, _i_, which are proposed to be about eighteen feet long, and three
in diameter. These bags are connected together at top and bottom
alternately, and through the whole series the smoke passes up one bag
and down the next, depositing fine black, called spirit black, upon the
sides of the canvass. After the jets have continued burning for several
days, the bags are to be beaten with a stick, so that the black may fall
to the bottom; and, when a sufficient quantity has accumulated, the bags
may be emptied and swept out. Thus seventy or eighty bags may be
employed; so that the smoke should pass through a length of about 400
yards, the farthest of which will be found to contain the finest black.
The last bag should be left open, in order to allow the vapour to escape
into the open air.

The main tar tube will require to be emptied every four or five days, in
order to clear it from the pitchy matter that may have subsided from the
burners, and they also will require to be frequently poked with a wire,
to clear off the black which forms upon the edges, and to drive down the
carbonized tar which attaches itself to the upper part of the jets.


BLEACHING (_Blanchiment_, Fr.; _Bleichen_, Germ.) is the process by
which the textile filaments, cotton, flax, hemp, wool, silk, and the
cloths made of them, as well as various vegetable and animal substances,
are deprived of their natural colour, and rendered nearly or altogether
white. The term bleaching comes from the French verb _blanchir_, to
whiten. The word _blanch_, which has the same origin, is applied to the
whitening of living plants by making them grow in the dark, as when the
stems of celery are covered over with mould.

The operations which the bleacher has recourse to differ according to
the nature of the bleaching means, the property of the stuff to be
bleached, and local customs or circumstances; and the result is also
obtained with more or less rapidity, certainty, economy, and perfection.
The destruction of the colouring matters attached to the bodies to be
bleached is effected either by the action of the air and light, of
chlorine, or sulphurous acid; which may be considered the three
bleaching powers employed for manufacturing purposes.

Bleaching by the influence of air and sunshine is the most ancient, and
still the most common, method in several civilised countries; it is also
supposed by many to be the least injurious to the texture of yarn and
cloth. The operations it involves are very simple, consisting in the
exposure of the goods upon a grass-plat to the sky, with their
occasional aspersion with moisture if necessary, in addition to the rain
and dew. The atmospheric air effects the bleaching by means of its
oxygenous constituent, which combines with the colouring matter, or its
elements carbon and hydrogen, and either makes it nearly white, or
converts it into a substance easily soluble in water and alkaline
solutions. This natural process is too slow to suit the modern demands
of the cotton and linen manufacturers. Fortunately for them, a new
bleaching agent, unknown to our forefathers, has been discovered in
chlorine, formerly called oxymuriatic acid, an agent modified by
chemistry so as to give an astonishing degree of rapidity, economy, and
perfection, to this important art. It is, however, not a little
surprising, that the science which has so greatly advanced its practical
part should have left its theory far from complete, and should afford no
satisfactory answers to the two following questions.--What is the action
of the solar rays upon the colouring matter? How do air and chlorine
operate upon this principle? Some suppose that light _predisposes_ the
colouring matter to combine with oxygen; others fancy that it acts
merely in the manner of a high temperature, so as to determine a
reaction between the elements of that substance, and to cause a new
combination possessed of peculiar properties. It is generally admitted
at the present day, that a portion of the oxygen of the air passes into
the colouring matter, and changes its constitution. This is, however,
probably not the part which oxygen plays, nor is it the only principle
in the atmosphere which exercises a bleaching influence. Neither is the
action of chlorine such as has been commonly represented in our chemical
systems.

But if authors offer us only vague hypotheses concerning the three
principal agents, light, oxygen, chlorine, they afford no information
whatever concerning the phenomena due to greasy spots so frequently
found upon cotton cloth, and so very troublesome to the bleacher. It has
indeed been sometimes said in bleach-works, that fatty substances are no
longer soluble in alkalies when they are combined with oxygen. The very
reverse of this statement is probably nearer the truth.

The object of bleaching is to separate from the textile fibre, by
suitable operations, all the substances which mask its intrinsic
whiteness; or which, in the course of ulterior dyeing operations, may
produce injurious effects. In this latter respect, cotton deserves
especial consideration. This substance is covered with a resinous
matter, which obstructs its absorption of moisture, and with a yellow
colouring matter in very small quantity, often so inconsiderable in some
cottons, that it would be unnecessary to bleach them, before submitting
them to the dyer, were it not that the manipulations which they undergo
introduce certain impurities which are more or less injurious, and must
be removed. It is in fact a circumstance well known in the factories,
that unbleached cottons may be dyed any dark colour, provided they are
deprived of that matter which makes them difficult to moisten. The
substances present in cotton goods are the following:--

1. The resinous matter natural to the cotton filaments.

2. The proper colouring matter of this vegetable.

3. The paste of the weaver.

4. A fat matter.

5. A cupreous soap.

6. A calcareous soap.

7. The filth of the hands.

8. Iron, and some earthy substances.

1. The matter which prevents the moistening of cotton wool may be
separated by means of alcohol, which, when evaporated, leaves thin
yellowish scales, soluble in alkalies, in acids, and even in a large
quantity of boiling water. For a long time the bleaching process
commenced with the removal of this resinous stuff, by passing the cloth
or the yarn through an alkaline ley. This was called scouring; it is now
nearly laid aside.

2. The colouring matter of cotton seems to be superficial, and to have
no influence on the strength of the fibres; for the yarn is found to be
as strong after it has been stripped by caustic soda of its resinous and
colouring matters, as it was before. The colouring matter is slightly
soluble in water, and perfectly in alkaline leys. When gray calico is
boiled in lime water, it comes out with a tint darker than it had
before; whence it might be supposed that the colouring matter was not
dissolved out, even in part. This, however, is not the case; for if we
filter the liquor, and neutralise it with an acid, we shall perceive
light flocks, formed of the resinous substance, united with the
colouring matter. The dark colour of the cloth is to be ascribed solely
to the property which lime possesses of browning certain vegetable
colours. This action is here exercised upon the remaining colour of the
cloth.

It may be laid down as a principle, that the colouring matter is not
directly soluble by the alkalies; but that it becomes so only after
having been for some time exposed to the joint action of air and light,
or after having been in contact with chlorine. What change does it
thereby experience, which gives it this solubility? Experiments made
upon pieces of cloth placed in humid oxygen, in dry oxygen, in
moist chlorine, and in dry chlorine, tend to show that hydrogen is
abstracted by the atmosphere; for in these experiments proofs of
_dis-hydrogenation_ appeared, and of the production of carbonic acid. In
all cases of bleaching by chlorine, this principle combines immediately
with the hydrogen of the colouring matter, and forms muriatic acid,
while the carbon is eliminated.

Undoubtedly water has an influence upon this phenomenon, since the
bleaching process is quicker with the humid chlorine than with the dry;
but this liquid seems to act here only mechanically, in condensing the
particles of the gas into a solution. We should also take into account
the great affinity of muriatic acid for water.

3. The weaver’s dressing is composed of farinaceous matters, which are
usually allowed to sour before they are employed. It may contain glue,
starch, gluten; which last is very soluble in lime-water.

4. When the dressing gets dry, the hand-weaver occasionally renders his
warp-threads more pliant by rubbing some cheap kind of grease upon them.
Hence it happens, that the cloth which has not been completely freed
from this fatty matter will not readily imbibe water in the different
bleaching operations; and hence, in the subsequent dyeing or dunging,
these greasy spots, under peculiar circumstances, somewhat like
lithographic stones, strongly attract the aluminous and iron mordants,
as well as the dye stuffs, and occasion stains which it is almost
impossible to discharge. The acids act differently upon the fatty
matters, and thence remarkable anomalies in bleaching take place. When
oil is treated with the acetic or muriatic acid, or with aqueous
chlorine, it evolves no gas, as it does with the sulphuric and nitric
acids, but it combines with these substances so as to form a compound
which cannot be dissolved by a strong boiling ley of caustic soda.
Carbonic acid acts in the same way with oil. On the other hand, when the
oils and fats are sufficiently exposed to the air, they seize a portion
of its oxygen, and become thereby capable of saponification, that is,
very soluble in the alkalies.

5. When the hand-weaver’s grease continues in contact for a night with
the copper dents of his reed, a kind of cupreous soap is formed, which
is sometimes very difficult to remove from the web. Lime-water does not
dissolve it; but dilute sulphuric acid carries off the metallic oxide,
and liberates the margaric acid, in a state ready to be acted on by
alkalis.

6. When cloth is boiled with milk of lime, the grease which is
uncombined unites with that alkaline earth; and forms a calcareous soap,
pretty soluble in a great excess of lime-water, and still more so in
caustic soda. But all fats and oils, as well as the soaps of copper and
lime, cease to be soluble in alkaline leys, when they have remained a
considerable time upon the goods, and have been in contact with acetic,
carbonic, muriatic acids, or chlorine. These results have been verified
by experiment.

7. Cotton goods are sometimes much soiled, from being sewed or tamboured
with dirty hands; but they may be easily cleansed from this filth by hot
water.

8. Any ferruginous or earthy matters which get attached to the goods in
the course of bleaching, are readily removable.

We are now prepared to understand the true principles of bleaching
cotton goods, for the most delicate operations of the calico printer.

1. The first process is steeping, or rather boiling, the goods in water,
in order to remove all the substances soluble in that liquid.

2. The next step is to wash or scour the goods by the dash-wheel or the
stocks. This is of great importance in the course of bleaching, and must
be repeated several times; so much so, that in winter, when the water of
the dash-wheel is cold, the bleaching is more tedious and difficult.
Yarn and very open fabrics do not much need the dash-wheel.

By these first two operations, the woven goods lose about sixteen per
cent. of their weight, while they lose only two parts out of five
hundred in all the rest of the bleaching.

3. In the third place the calicoes are boiled with milk of lime, whereby
they are stripped of their gluten, and acquire a portion of calcareous
soap. Formerly, and still in many bleach-works, the gluten was got rid
of by a species of fermentation of the farinaceous dressing; but this
method is liable to several objections in reference to the
calico-printer. 1. The fermentative action extends sometimes to the
goods, and weakens their texture, especially when they are piled up in a
great heap without being previously washed. 2. The spots of grease, or
of the insoluble soaps, become thereby capable of resisting the caustic
alkalies, and are rendered in some measure indelible; an effect due to
the acetic and carbonic acids generated during fermentation, and which
will be easily understood from what has been said concerning the action
of acids on fatty substances. It is not, therefore, without good reason
that many practical men throw some spent leys into the fermenting vats,
to neutralise the acids which are formed. Were it not for the presence
of fat, fermentation, skilfully conducted, would be an excellent means
of carrying off the gluten; and the steep is therefore applicable to
power-loom goods, which are not polluted with grease.

4. The goods are now subjected to a caustic soda ley, which dissolves
out the soaps of lime and copper, as well as that portion of the
colouring matter which is sufficiently dis-hydrogenated to be capable of
combining with it. This bucking with ley, which is repeated several
times upon the goods, in order to purge them completely from the fatty
matter present in the hand-loom webs, and also partially introduced in
the spinning, is almost the only operation to which yarns for turkey red
are subjected. After being boiled in a caustic soda ley, they are passed
through solutions of chloride of lime, and afterwards through the acid
steep.

5. When the goods are sufficiently bucked in the leys, they are either
exposed to chlorine, or laid out on the grass; sometimes both are had
recourse to for delicate work. These different modes of action have the
same influence on the colouring matter, but they give rise to different
effects in reference to greasy stains.

The goods are dipped in a solution of chloride of lime, which should be
kept tepid by means of steam. Alongside of the chlorine cistern, there
is another filled with dilute sulphuric or muriatic acid. When the goods
are taken out of the chlorine, they are drained on the top of its
cistern till no more liquid runs off them, and they are then plunged
into the _sour_. The action of the acid in the present case may be
easily explained. In proportion as a salt of lime is formed, this base
quits the chlorine, and allows it to act freely upon the colouring
matter. Thus we prevent the development of too great a quantity of
chlorine at once, which would be apt to injure the fibres; and we pursue
both a prudent and economical plan. Only so much chlorine as is strictly
necessary is called forth, and hence it excites no smell in the
apartment.

The chlorine serves to acidify the colouring matter, by abstracting a
portion of its hydrogen; but we must take the greatest care that there
is no grease upon the goods before immersion in it, for the consequence
would be, as above shown, very troublesome spots. When the cloth is laid
out upon the grass, it is the oxygen of the air which acidifies the
colouring matter; for which reason, the dew, which contains much air
rich in oxygen, singularly accelerates the bleaching process. It is
likewise, by absorbing oxygen from the atmosphere, that fats or oils
pass to the state of margaric and oleic acids, and become most easily
saponified. Should the goods, however, be left too long on the grass,
the fats absorb carbonic acid, and become insoluble in leys.

6. The goods must now receive a new soda ley, to dissolve out that
portion of the colouring matter which has been dis-hydrogenated in the
chlorine of the air, as well as the grease, if any perchance remained in
the soluble state. These last two operations are to be several times
repeated, because the colouring matter should be removed only by
degrees, for fear of injuring the texture of the goods, by subjecting
them to too much chlorine at a time.

7. We finish with the dilute sulphuric acid, which should be very weak
and tepid. It dissolves out the iron, and some earthy matters
occasionally found upon cotton. The goods must be most carefully washed
at the dash-wheel, or in a stream of water on quitting the sour bath,
for if the acid were allowed to dry in them, it would infallibly injure
their texture by its concentration. In winter, if the goods are allowed
to get frozen with the acid upon them, they may likewise be damaged.

We may here observe, that when the goods are not to remain white, their
bleaching may be completed with a ley; for though it leaves a faint
yellow tint, this is no inconvenience to the dyer. But when they are to
be finished with a starching after the last ley, they must have another
dip of the chlorine to render the white more perfect. An immersion in
the dilute acid has nearly the same effect.

The principles expounded above lead to this important consequence, that
when we wish to bleach goods that are free from greasy stains, as is the
case generally with the better kinds of muslins, or when we wish to
bleach even greasy goods for the starch finish, we may content ourselves
with the following operations:--

1. Boiling in water.

2. Scouring by the stocks or the dash-wheel.

3. Bucking with milk of lime.

4. Passing through chlorine, or exposure on the grass.

5. Bucking, or bouking with milk of lime. These two latter operations
require to be alternated several times, till the whole of the colouring
matter be removed.

6. Souring.

The bleaching of goods, which are never laid down on the green, and
which are not dried between two operations, may be completed in a couple
of days. They answer as well for the printer as the others, and they are
as white. Cotton fibres or yarns suffer no diminution of their strength,
when the cloth has been properly treated in the above described
processes.

Accurate experiments have demonstrated that their strength is not
impaired by being boiled in milk of lime for two hours at the ordinary
pressure, provided they be constantly kept covered with liquid during
the whole ebullition, and that they be well washed immediately
afterwards; or, by being boiled in pure water under the pressure of ten
atmospheres of steam; or by being boiled under the same pressure in a
caustic soda ley, marking 3° of Tweedale, or specific gravity 1·015,
though it has increased to double the density in the course of the boil,
by the escape of the steam; or by being boiled under the atmospheric
pressure at 14° of Tweedale, or specific gravity 1·070; or by being
immersed for eight hours in chloride of lime, capable of decolouring
three times its bulk, of test solution of indigo (see CHLORINE); and by
being afterwards dipped in sulphuric acid of specific gravity 1·067,
Tweedale 14°; or by being steeped for eighteen hours in sulphuric or
muriatic acid of specific gravity 1·035, 7° Tweedale.

In other well-conducted bleach-works the following is the train of
operations:-- 1. Cleansing out the weaver’s dressing by steeping the
cloth for twelve hours in cold water, and then washing it at the stocks
or the dash-wheel. 2. Boiling in milk of lime, of a strength suited to
the quality of the goods, but for a shorter time than with the soda ley;
two short operations with the lime, with intermediate washing, being
preferable to one of greater duration. 3 and 4. Two consecutive leys of
ten or twelve hours’ boiling, with about two pounds of soda crystals for
1 cwt. of cloth. 5. Exposure to the air for six or eight days, or the
application of the chloride of lime and the sulphuric acid. 6. A ley of
caustic soda, like the former, sometimes with less alkali. 7. Exposure
to the air for six or eight days, or chlorine and the sour, as above. 8.
Caustic soda ley, as before. 9. Chlorine and the sour. 10. Rinsing in
hot water, or scouring at the dash-wheel.

If the number of vessels to be heated exceeds four or five, there is an
economy in using steam as the medium of heat; but under this number
there is an advantage in the direct application of fire to a boiling or
bucking apparatus; since when only two vessels are in activity, there is
a waste of fuel by the extra steam power. It deserves to be remarked
also, that the increase of the bulk of the liquid by the condensation of
the steam, does not permit the spent white ley to be turned to use for
the green goods, on account of its excessive dilution. With the milk of
lime boil, however, this dilution would be rather an advantage.

It has been found that the introduction of bran into the fermenting
steep (when this is used) endangers the texture of the goods, by causing
a putrefactive fermentation in some places.

When in the milk of lime boil there is too much of this caustic earth,
or when it is poured in on the top of the goods, they are apt to suffer
damage. The milk of lime should be introduced from beneath into the
under compartment of the bucking apparatus. For the same reason, after
the caustic soda lye, the vessel should be filled up with water, if the
goods be not immediately transferred to the dash-wheel. When they are
allowed to become partially dry on the top, they are easily injured. The
copper of the bucking apparatus ought to be of a size proportioned to
that of the surmounting crib or vat; for when it is too small, the
liquid is too long of being brought into proper circulation, and the
goods may be meanwhile injured. In a bucking apparatus, which requires
five or six hours to be brought into full play, those goods are very apt
to be injured, which lie immediately under the overflow pipe.

When the chloride of lime steep is too strong, sometimes small round
holes are made in the calico, just as if they had been cut out by a
punch, especially in the borders or thicker parts of the goods. This
accident is owing to the presence of bubbles of chlorine. From the
saturated state of the liquid, they remain gaseous a sufficient length
of time for corroding the parts of the cloth with which they are in
contact. These will be obviously the denser parts, for they confine the
gas most completely, or prevent its diffusion through the mass. This
evil is prevented by diluting the chloride steep to the proper degree,
and moving the goods through it.

The greasy spots, described above, show themselves in the maddering by
attracting the dye-stuff more copiously than the pure parts of the
cloth, so as to mottle it; they are also recognised in the white goods
by being somewhat repulsive of moisture. When the combination of fatty
matters with chlorine takes place at the surface of cotton goods, it is
of a nature to resist the action of alkalies. It is the stearine, or the
principle of suet, particularly, which, by this means, acquires such a
strong affinity for cottons; the elaine, or the principle of oils, has
no such remarkable affinity. Lime, in some circumstances, seems to act
as a mordant to greasy matters, and to fix them fast. Hence the weaver
should be prohibited, in all cases, from allowing candle-grease to touch
his web. Goods soiled with it should never be allowed to lie by in the
warehouse, but be immediately cleansed before the air has fixed the
stearine by converting it into margaric acid. Lime should, in these
cases, be prudently employed; chlorine should never be used till the
greasy stains are thoroughly removed; and the bleacher should never
warrant his pieces for the printer till he has verified some of them by
the water test.

I shall conclude this general analysis of the principles of bleaching by
a few precepts. Avoid lime, at the first ley, for goods which contain
greasy spots; but use it freely after one or two soda leys, and apply
two soda leys after it. Do not apply chlorine between these leys, but
reserve it for the final operation. By this plan the goods will be well
bleached, and very little worn. Use the souring steeps freely, giving
them after each ley, whether of lime or soda, since the calcareous base,
with which the greasy spots get charged merely from hard water, is an
obstacle to the further action of the leys.

I shall now give some practical instructions concerning the several
steps of the bleaching process, as applied to cotton, linen, silk, and
wool.

The first thing which the cotton bleacher does, is to mark the pieces
with the initials of the owner, by means of a stamp imbued with coal
tar. The linen bleacher marks with nitrate of silver, a far more
expensive substance, but one which resists better the severer treatment
which his goods are destined to undergo.

The cotton goods are generally singed before they are sent to the
bleacher, and this is done either by passing them rapidly over a red-hot
semi-cylinder of iron, or over a row of gas flames, by Mr. Hall’s
ingenious contrivance. (See SINGEING.) Each piece is next creased
together lengthwise like a rope, folded into a bundle, and fixed by a
noose at the end. In this open state it is easily penetrated by the
water of the soaking cistern into which it is thrown. It is then scoured
by the dash or wash-wheel. It is now ready for the bucking or steaming
apparatus, where it is treated with milk of lime. The steam chamber
resembles the bucking vessel, without its bottom copper; that is to say,
a few inches below the grated bottom of the bucking tub, there is a
close iron sole, through the centre of which the steam is admitted by
several small apertures, for the purpose of diffusing it throughout the
goods, and causing a liquid circulation by its pressure, as the steam
does in the proper bucking boiler. One pound of lime previously made
into a cream consistenced mixture, and passed through a sieve, is used
for every thirty or forty pounds of cloth, according to its colour and
texture; and this cream mixed with more water is interstratified with
the pieces, as they are laid regularly in the vessel. Whenever this is
stocked with goods, all their interstices are filled up with water.
After the lime bucking, the cloth is transferred to the dash-wheel.

A pound of cloth requires for its whitening about half a pound of good
average chloride of lime or bleaching powder, as it is commonly called,
and this ought to be dissolved in about three gallons of water. Mr. Crum
of Thorniebank, near Glasgow, an extensive and excellent bleacher, has
so modified Dr. Dalton’s ingenious plan of testing the power of
bleaching liquors by green sulphate of iron, as to give it much greater
precision for the bleacher’s use, than the discolouration of indigo
originally proposed by Berthollet. Mr. Crum dissolves four ounces of
fresh green vitriol in hot water, and then adds the solution of
bleaching powder by small quantities at a time, till the iron becomes
wholly peroxidised, when the smell of chlorine will become perceptible.
When the bleacher has once found by trial the proper blanching power
which his chlorine steep ought to have, he can verify its standard, by
seeing how much of it must be added to an ounce, or any given weight of
fresh copperas, dissolved in hot water, to cause the peroxidisement and
the exhalation of the peculiar odour. M. Gay Lussac’s new method by
arsenious acid will be described under chlorine. From the experiments
which I made some years ago[9], upon indigo, it will be seen that this
dye stuff is so variable in its quantity of colouring matter, that no
two chemists operating with it independently, as a test for chloride of
lime, could arrive at the same result. They must provide themselves with
absolute indigo, by an expensive and troublesome process, not suited to
the busy bleacher. The vitriolage, as the French term it, or the souring
of the English bleacher, consists in immersing the goods for four hours
in dilute sulphuric acid, containing one gallon of oil of vitriol to
from 25 to 30 of water, thoroughly intermixed by stirring; for the
density of the acid is an obstacle to its equal distribution through the
water. This dilute acid will have a density of from 1·047 to 1·040, and
will contain from 7 to 6-1/2 per cent. by weight of the oil of vitriol.

  [9] Quarterly Journal of Science, Literature, and the Arts, vol. vii.
  p. 160.

The goods are now washed, and then boiled for eight or nine hours in an
alkaline ley, containing about two pounds of crystals of soda, or their
equivalent in soda ash or pearl-ash, for every 100 lbs. of cloth. The
ley must be made previously caustic by quick lime. A washing in the
wheel follows this boil; and then a chlorine steep for five hours in a
liquor two thirds of the strength of the former. It is next soured in
the dilute sulphuric acid, for two, three, or four hours, according to
the colour and quality of the cotton, and then thoroughly washed.

The cloth is now bleached white, but cannot be presented in the market
till it undergoes certain finishing processes. The piece is elongated
from the folds which it contracts during the rotation of the dash-wheel,
by being thrown into a stream of water in a cistern, terminated by the
squeezing rollers, which take in the end of the piece, and run it
through between them, with the effect of making it nearly dry. Two
pieces of cloth pass simultaneously through the rollers, and are
disentangled spontaneously, so to speak, without the help of hands.

[Illustration: 117 118]

The squeezing rollers or squeezers, for discharging the greater part of
the water from the yarns and goods in the process of bleaching, are
represented in _figs._ 117, 118., the former being a side-view, to show
how the roller gudgeons lie in the slots of the frame, and how the shaft
of the upper roller is pressed downward by a weighted lever, through a
vertical junction road, jointed at the bottom to a nearly horizontal
bar, on whose end the proper weight is hung. In _fig._ 118. these
rollers of birch-wood are shown in face; the under one receiving motion
through the toothed wheel on its shaft, from any suitable power of water
or steam. Upon the shaft of the latter, between the toothed wheel and
the roller, the lever and pulley for putting the machine into and out of
geer is visible. The under roller makes about 25 revolutions in the
minute, in which time three pieces of goods, stitched endwise, measuring
28 yards each, may be run through the machine, from a water trough on
one side, to a wooden grating upon the other.

When the goods are run through, they are carried off upon a grated
wheelbarrow, in a nearly dry state, and transferred to the spreading
machine, called at Manchester a _candroy_. In many bleach-works,
however, the creased pieces are pulled straight by the hands of women,
and are then strongly beat against a wooden stock to smooth out the
edges. This being done, a number of pieces are stitched endwise
together, preparatory to being mangled.

[Illustration: 119 120 121]

_Calender._--_Fig._ 120. is a cross section of this machine, and _figs._
119. 121. are front views broken off. The goods are first rolled upon
the wooden cylinder _a_, near the ground; by the tension roller _b_,
upon the same cylinder, the goods receive a proper degree of stretching
in the winding off. They then pass over the spreading bars _c c c_, by
which they are still more distended; next round the hollow iron cylinder
_d_, 16 inches diameter, and the paper cylinder _e_, of like dimensions;
thence they proceed under the second massive iron cylinder _f_, of 8
inches diameter, to be finally wound about the projecting wooden roller
_g_. This is set in motion by the pulleys _h_, _fig._ 121., and _i_,
_fig._ 120., and receives its proper tension from the hanging roller
_k_; _l_ is a press cylinder, of 14 inches diameter, made of plane-tree
wood. By its means we can at all times secure an equal degree of
pressure, which would be hardly possible did the weighted lever press
immediately upon two points of the calender rollers. The compression
exercised by the cylinders may be increased at pleasure by the bent
lever _m_, weights being applied to it at _n_. The upper branch of the
lever _o_ is made fast by screws and bolts at _p_, to the upper
press-cylinder. The junction leg _q_ is attached to the intermediate
piece _r_, by left and right-handed screws, so that according as that
piece is turned round to the right or the left, the pressure of the
weighted roller will be either increased or diminished. By turning it
still more, the piece will get detached, the whole pressure will be
removed, and the press-roller may be taken off; which is a main object
of this mechanism.

The unequable movement of the cylinders is produced by the wheels _s t
u_, of which the undermost has 69, the uppermost has 20, and the
carrier-wheel _t_, either 33, 32, or 20 teeth, according to the
difference of speed required. The carrier-wheel is bolted on at _v_, and
adjusted in its proper place by means of a slot. To the undermost iron
cylinder, the first motion is communicated by any power, for which
purpose either a rigger (driving pulley) is applied to its shaft at _u_,
or a crank motion. If it be desired to operate with a heated calender,
the undermost hollow cylinder may be filled with hot steam, admitted
through a stuffing box at one end, and discharged through a stuffing box
at the other, or by a red-hot iron roller.

Pure starch would be too expensive a dressing for common calico
shirtings, and therefore an extemporaneous starch is made by mixing one
pound of flour with one gallon of water, and allowing the mixture to
ferment in a warm place for twenty-four hours. In this way, a portion of
_lactic_ acid is formed, which dissolves the gluten, or separates it
from the starch; so that when the whole is thrown upon a sieve, a liquid
paste passes through, which, being boiled, answers well for stiffening
the goods, without giving them a gray tinge. The paste is thinned with
water to the desired degree, and faintly tinged with solution of indigo.
The starch, which is sometimes thickened with porcelain clay, Paris
plaster, or Spanish white, is put into a trough, and is evenly imparted
to the cloth as this is drawn down through it, by the traction of
rollers. There is a roller near the bottom of the trough, round which
the cloth is made to run, to secure its full impregnation; while the
upper rollers serve to expel its excess of the starch, and throw it back
into the cistern. See STARCHING APPARATUS.

The goods are next dried in an apartment heated by two, three, or more
flues, running along the floor, and covered usually with fire-tiles. At
first the heat is moderate, but it is gradually raised to upwards of
110° F.

The goods must now be passed again through the calender, in order to
receive their final smoothness and lustre. They are in the first place
damped with a peculiar machine, furnished with a circular brush, whose
points revolve in contact with water in a trough placed beneath them,
and sprinkle drops of water upon the goods as they are drawn forwards by
a pair of cylinders. They are then subjected to the powerful pressure of
the calender rollers.

The calendered pieces are neatly folded into compact parcels, and
stamped with the marks of each particular manufacturer, or various
devices to suit the markets for which they are designed. They are
finally piled on the sole of an hydraulic press, with a sheet of
pasteboard between each piece; but with occasional plates of iron to
secure uniformity of pressure throughout. When sufficiently condensed by
the press, they are taken out, and despatched to their respective
manufacturers in a state ready for sale.

There are no less than 25 steps in the bleaching of calicoes, many of
them effected with expensive machinery; yet the whole do not produce to
the bleacher more than 10 pence per piece, of 24 yards.

The following system was pursued a few years back, by a skilful bleacher
of muslins near Glasgow:--

“In fermenting muslin goods, we surround them with our spent leys, from
the temperature of 100° to 150° F., according to the weather, and allow
them to ferment for 36 hours. In boiling 112 lbs. = 112 pieces of
yard-wide muslin, we use 6 or 7 lbs. of pearl-ashes, and 2 lbs. of soft
soap, with 360 gallons of water, and allow them to boil for 6 hours;
then wash them, and boil them again with 5 lbs. of pearl-ashes, and 2
lbs. of soft soap, and allow them to boil 3 hours; then wash them with
water, and immerse them into the solution of oxymuriate of lime, at 5 on
the test-tube, and allow them to remain from 6 to 12 hours; next wash
them, and immerse them into dilute sulphuric acid at the specific
gravity of 3-1/2 on Tweedale’s hydrometer = 1·0175, and allow them to
remain an hour. They are now well washed, and boiled with 2-1/2 lbs. of
pearl-ashes, and 2 lbs. of soft soap for half an hour; afterwards washed
and immersed into the oxymuriate of lime as before, at the strength of 3
on the test-tube, which is stronger than the former, and allowed to
remain for 6 hours. They are again washed, and immersed in diluted
sulphuric acid at the specific gravity of 3 on Tweedale’s hydrometer =
1·015. If the goods be strong, they will require another boil, steep,
and sour. At any rate, the sulphuric acid must be well washed out before
they receive the finishing operation with starch.

“With regard to the lime, which some use instead of alkali immediately
after fermenting, the same weight of it is employed as of pearl-ashes.
The goods are allowed to boil in it for 15 minutes, but not longer,
otherwise the lime will injure the fabric.”

More recently the plan adopted is as follows; by which the purest whites
are produced for the London market.

“Lime is seldom used for our finer muslin goods, as it is found to
injure their fabric, and the colours do not keep for any length of time.

“An alkaline ley is made by boiling equal weights of lime and soda
together for an hour: this alkali is used for boiling goods the same as
potash, but without soap.

“In finishing jacounets or muslins, after washing them from the sour,
they are run through spring-water containing a little fine smalts, which
give them a clear shade; if of a coarse fabric, a little well-boiled
starch is added to the water. From this they are wrung or pressed, and
taken up by the selvage for the breadthing frame, and are run off it
upon a tin cylinder heated by steam, by which the piece is completely
dried in 15 minutes: it is then stripped from the cylinder, neatly
folded and pressed, which finishes the piece for the market. From 6_d._
to 9_d._ per piece of 12 yards is obtained for the bleaching and
finishing of those goods.

“Book muslins, after being washed from the sour, are wrung or pressed;
then they are hung up to dry in a heated stove, previous to being put
into starch, prepared by boiling 3 lbs. of it to every 5 gallons of
water, with 20 ounces of smalts: they are wrung out of this starch, and
taken to a room heated to 110° F.; the starch is wrought into the piece
till clear, then taken into a cold room, and the selvages dressed or
set, before being put on the breadthing frame in the heated stove, where
the piece is stretched to its length, while three or four persons at
each selvage keep the piece to its breadth. If a stiff finish is wanted,
they keep exactly opposite each other; but in breadthing the piece of
elastic, they cross the piece in breadthing, which gives it a springy
elastic finish. From 9_d._ to 15_d._ per piece of 12 yards is obtained
for the bleaching and finishing of these goods.

“Sewed trimmings, flounces, and dresses are run through spring water
containing fine smalts with a little well-boiled starch. They are then
taken to the drying stove, where they are stented till dry, which
finishes the piece for the market. From 6_d._ to 8_d._ per piece is
obtained for trimmings and flounces, and from 9_d._ to 1_s._ for
dresses, bleaching and finishing.”

In the bleaching of cotton cloth, where fixed colours are previously
dyed in the yarn before it is woven into cloth, such as the Turkey or
Adrianople red, and its compounds of lilac or purple, by the addition of
iron bases, various shades of blue from indigo, together with buff and
gold colour, tinged with the oxides of iron, great care is necessary.

The common process of bleaching pulicates, into which permanent colours
are woven, is, to wash the dressing or starch well out in cold water; to
boil them gently in soap, and, after again washing, to immerse them in a
moderately strong solution of the oxymuriate of potash; and this process
is followed until the white is good: they are then soured in dilute
sulphuric acid. If the goods are attended to in a proper manner, the
colours, in place of being impaired, will be found greatly improved, and
to have acquired a delicacy of tint which no other process can impart to
them.

Pulicates, or ginghams, which have been woven along with yarn which has
been previously bleached, are first freed by washing from the starch or
dressing: they are then washed, or slightly boiled with soap. After
which, they are completely rinsed in pure spring water, and then soured.

Besides these common processes for bleaching, another was some time ago
introduced, which consisted in immersing the cotton or linen goods in
pretty strong solution of caustic alkali, and afterwards exposing them
to the action of steam in a close vessel. It is now generally abandoned.

The cotton or linen goods having been previously cleaned by steeping and
washing, were, after being well drained, steeped in a solution of
caustic alkali of the specific gravity of 1020. After the superfluous
alkaline ley had been drained from them, they were arranged on a grating
in a receiver. The cover was then placed on the vessel, and firmly
screwed down; and the steam was admitted by turning the stop-cock of the
pipe which communicated with a steam boiler of the common construction.

The stains which come out upon maddered goods, in consequence of
defective bleaching, are called in this country _spangs_. Their origin
is such as I have described above, as the following statement of facts
will show. The weaver of calicoes receives frequently a fine warp so
tender from bad spinning or bad staple in the cotton, that it will not
bear the ordinary strain of the heddles, or friction of the shuttle and
reed, and he is obliged to throw in as much weft as will compensate for
the weakness or thinness of the warp, and make a good marketable cloth.
He of course tries to gain his end at the least expense of time and
labour. Hence when his paste dressing becomes dry and stiff, he has
recourse to such greasy lubricants as he can most cheaply procure; which
are commonly either tallow or butter in a rancid state, but the former
being the lowest priced is preferred. Accordingly, the weaver, having
heated a lump of iron, applies it to a piece of tallow held over the
warp in the loom, and causes the melted fat to drop in patches upon the
yarns, which he afterwards spreads more evenly by his brush. It is
obvious, however, that the grease must be very irregularly applied in
this way, and be particularly thick on certain spots. This irregularity
seldom fails to appear when the goods are bleached or dyed by the common
routine of work. Printed calicoes examined by a skilful eye, will be
often seen to be stained with large blotches evidently occasioned by
this vile practice of the weaver. The ordinary workmen call these
_copper_ stains, believing them to be communicated in the dyeing copper.
Such stains on the cloth are extremely injurious in dyeing with the
indigo vat. The following plan is adopted by some Scotch bleachers with
the effect, it is said, of effectually counteracting spangs from grease.

The goods having been singed and steeped in pure water, as is customary
in common bleaching, they are passed through a pair of rollers to press
out the impurities which have been loosened by the steeping. It must
here, however, be observed, that where the expense of one extra drying
can be afforded, the process might be very much improved by steeping the
brown calicoes for thirty or forty hours before singeing, because this
would separate much of that impurity which usually becomes fixed in the
stuff on its being passed over the hot cylinders. When the pieces have
been thus singed, steeped, and pressed, they are boiled four times, ten
or twelve hours at each time, in a solution of caustic potash, of the
specific gravity of from 1·0127 to 1·0156, washing them carefully and
thoroughly in pure water between each of these boilings. They are then
immersed in a solution of the chloride of potash, originally of the
strength of 1·0625, and afterwards reduced with twenty-four times its
measure with water.

When the preparation is good, these proportions will whiten cotton goods
completely in eight hours. In this steep they are, however, generally
suffered to remain twelve hours. It has been supposed that the common
bleaching liquor (chloride of lime) cannot, without injury, be
substituted for chloride of potash, but I believe this to be a mistake.

Some printers take the pieces from this solution, and, while wet, lay
them upon the grass, and there expose them to the sun and weather for
two or three days. They are thence removed to the sours, made of the
specific gravity of about 1·0254 at the temperature of 110° of
Fahrenheit. In bleaching common goods, and such as are not designed for
the best printing, the specific gravity of the sours is varied from that
of 1·0146 to that of 1·0238, if weighed when they become of the
temperature of the atmosphere. In these they are suffered to lie for
five or six hours, after which they are taken to the dash-wheel and
washed thoroughly. When this operation is finished, they are submitted
to four more boilings as before, with a solution of caustic potash;
taking care to wash well between each of these boilings. Sometimes
pearl-ash, made caustic, is used for the last of these boilings, lest
the sulphur, which always exists in the potashes of commerce, should
impair the whites. They are next immersed in the diluted chloride of
potash, of the strength before mentioned; after which they are well
washed in pure water, and then winched for half an hour in common sours.
The last process is that of careful washing in plenty of clean water,
after which they are not put into the stove, but are immediately hung up
in the airing sheds to dry gradually. The water must be good, and
abundant.

The number of operations, as here described, is great; but I know of no
other mode of procedure by which perfect bleaching is so likely to be
effected at all times and in all seasons, without disappointment. It
must here be remarked, that, for the best purposes of printing, it would
not be sufficient to take goods which have been bleached in the common
way and finish these by the better process; because the sulphate of lime
deposited in the cloth by that operation will be apt to spoil them for
madder colours; at least, a printer who is curious in his business would
hesitate to work up such cloth.

_Bucking or Bowking._--This is one of the most important operations in
the bleaching of both cotton and linen goods. There are several methods
whereby this process is carried on; but of these we shall select only
two, distinguishing them as the old and new method of bucking. In the
former way, the cloths have been steeped in the alkaline lye, as before
described, and afterwards well washed, are regularly arranged in a large
wooden vat, or kieve; a boiler of sufficient capacity is then filled
with caustic alkaline lye, which is heated to the temperature of blood.
The boiler is then emptied by a stop-cock upon the linens in the kieve,
until they are covered with the liquor. After having remained on the
cloth for some time, it is run off by a stop-cock, at the bottom of the
kieve, into an iron boiler sunk in the ground, from whence it is raised
into the boiler by a pump. The heat is now elevated to a higher
temperature, and the lye again run upon the goods in the kieve; from
whence it is returned into the boiler, as before described: and these
operations are continued, always increasing the heat, until the alkaline
lye is completely saturated with the colouring matter taken from the
cloth, which is known by its having acquired a completely offensive
smell, and losing its causticity.

When we consider the effect which heated liquids have upon coloured
vegetable matter, we shall see the propriety of the temperature of the
alkaline lye being gradually increased. Thus, when vegetable substances
are hastily plunged into boiling liquids, the colouring matter, in place
of being extracted, is, by this higher temperature, fixed into them. It
is on this principle that a cook acts in the culinary art, when the
green colour of vegetables is intended to be preserved: in place of
putting them into water when cold, they are kept back until the water is
boiling; because it is well known that, in the former case, the green
colour would be entirely extracted, whereas, when the vegetables are not
infused until the water is boiling, the colour is completely preserved
or fixed. On the same principle, when the temperature of the alkaline
lye is gradually raised, the extractive and colouring matter is more
effectually taken from the cloth; and the case is reversed when the lye
is applied at the boiling temperature: so much so, that linen which has
been so unfortunate as to meet with this treatment, can never be brought
to a good white.

When the alkaline lye is saturated with colouring matter, it is run off
as unfit for further use in this operation; but, were the goods to be
instantly taken out of the kieve, and carried to be washed in the
dash-wheel while hot, a certain portion of the colouring matter would be
again fixed into them, which is extremely difficult to eradicate. In
order to prevent this, the most approved bleachers run warm water upon
the cloth as soon as the impure lye is run off: this combines with and
carries off part of the remaining impurities. A stream of water is then
allowed to run upon the cloth in the kieve, until it comes off almost
transparent. The goods are now to be taken to the wash-stocks, or to the
dash-wheel, to be further cleaned, with the greatest efficacy.

The improved mode of bowking was the invention of Mr. John Laurie, a
native of Glasgow. It is now practised by many bleachers in Lancashire,
some on more perfect plans than others; but we shall give the
description of the kind of apparatus approved of by those whose
experience and skill have rendered them the most competent judges.

[Illustration: 122]

In _fig._ 122., A B C D is the wooden kieve, or kier, containing the
cloth; C E F D represents the cast-iron boiler; G G, the pump; _g_ K,
the pipe of communication between the kieve and the boiler. This pipe
has a valve on each of its extremities: that on the upper extremity,
when shut, prevents the lye from running into the boiler, and is
regulated by the attendant by means of the rod and handle _g_ B. The
valve at K admits the lye; but, opening inwards, it prevents the steam
from escaping through the pipe _g_ K. The boiler has a steam-tight iron
cover, _g_ L; and at C D, in the kieve, is a wooden grating, a small
distance above the cover of the boiler.

At M O is a broad plate of metal, in order to spread the lye over the
cloth. It is hardly necessary to say that the boiler has a furnace, as
usual, for similar purposes.

While the lye is at a low temperature, the pump is worked by the mill or
steam-engine. When it is sufficiently heated, the elasticity of the
steam forces it up through the valves of the pump, in which case it is
disjoined from the moving power.

N P is a copper spout, which is removed at the time of taking the cloth
out of the kieve.

[Illustration: 123]

The boilers A, _fig._ 123., used in bleaching, are of the common form,
having a stopcock, H G, at bottom, for running off the waste lye. They
are commonly made of cast iron, and are capable of containing from 300
to 600 gallons of water, according to the extent of the business done.
In order that the capacity of the boilers may be enlarged, they are
formed so as to admit of a crib of wood, strongly hooped, or, what is
preferable, of cast iron, to be fixed to the upper rim or edge of it. To
keep the goods from the bottom, where the heat acts most forcibly, a
strong iron ring, covered with netting made of stout rope, C, is allowed
to rest six or eight inches above the bottom of the boiler. Four double
ropes are attached to the ring E, for withdrawing the goods when
sufficiently boiled, which have each an eye for admitting hooks from the
running tackle of a crane. Where more boilers than one are employed, the
crane is so placed, that, in the range of its sweep, it may withdraw the
goods from any of them. For this purpose, the crane turns on pivots at
top and bottom; and the goods are raised or lowered at pleasure, with
double pulleys and sheaves, by means of a cylinder moved by cast-iron
wheels. The lid is secured by the screw bolts D D, and rings B B. F is a
safety valve.

The efficacy of Laurie’s bowking apparatus is remarkable. While the heat
is gradually rising, a current of fresh lye is constantly presented to
the different surfaces for saturating the goods, so as to increase its
detersive powers. Besides, the manner in which the apparatus is worked,
first by the water-wheel or steam-engine, and then by its intrinsic
operation, puts it completely out of the power of servants to slight the
work; not to speak of the great saving of alkali, which, in many cases,
has been found to amount to 25 per cent.

[Illustration: 124 125 126]

A simple modification of the bowking apparatus is shown in _figs._ 124,
125, 126.; the first being a vertical section, the second, a horizontal
section in the line _x_ of the first. It consists of two parts: the
upper wide part, _a a_, serves for the reception of the goods, and the
lower or pot, _b_, for holding the lye; _c c_ is an iron grating, shown
apart in _fig._ 126. The grating has numerous square apertures in the
middle of the disc, to which the rising pipe _d_ is screwed fast. The
upper cylinder is formed of cast iron, or of sheet iron well rivetted at
the edges; or sometimes of wood, this being secured at its under edge
into a groove in the top edge of the lye-pot. The mouth of the cylinder
is constructed usually of sheet iron. _e e_ is the fire-grate, whose
upper surface is shown in _fig._ 125.: it is made of cast iron, in three
pieces. The flame is parted at _f_, and passes through the two apertures
_g g_, into the flues _h h_, so as to play round the pot, as is visible
in _fig._ 125.; and escapes by two outlets into the chimney. The
apertures _i i_ serve for occasionally cleaning out the flues _h h_, and
are, at other times, shut with an iron plate. In the partition _f_,
which separates the two openings _g g_, and the flues _h h_, running
round the pot, there is a circular space at the point marked with _k_,
_fig._ 125., in which the large pipe for discharging the waste lye is
lodged. The upper large cylinder should be encased in wood, with an
intermediate space filled with sawdust, to confine the heat. The action
of this apparatus is exactly the same as of that already explained.

Besides the boiling, bucking, and other apparatus above described, the
machinery and utensils used in bleaching are various, according to the
business done by the bleacher. When linen or heavy cotton cloths are
whitened, and the business is carried on to a considerable extent, the
machines are both complicated and expensive. They consist chiefly of a
water-wheel, sufficiently powerful for giving motion to the wash-stocks,
dash-wheels, squeezers, &c., with any other operations where power is
required.

[Illustration: 127 128]

_Figs._ 127, 128. represent a pair of wash-stocks. A A are called the
stocks, or feet. They are suspended on iron pivots at B, and receive
their motion from wipers on the revolving-shaft C. The cloth is laid in
at D, and, by the alternate strokes of the feet, and the curved form of
the turnhead E, the cloth is washed and gradually turned. At the same
time, an abundant stream of water rushes on the cloth throughout holes
in the upper part of the turnhead. Wash-stocks are much used in Scotland
and in Ireland. In the latter country, they are often made with double
feet, suspended above and below two turnheads, and wrought with cranks
instead of wipers. Wash-stocks, properly constructed, make from 24 to 30
strokes per minute.

This mode of washing is now entirely given up in Lancashire, where a
preference is given to what are called dash-wheels and squeezers. The
dash are small water-wheels, the inside of which is divided into four
compartments, and closed up, leaving only a hole in each compartment for
putting in the cloth.

There are, besides, smaller openings for the free admission and egress
of the water employed in cleansing. The cloth, by the motion of the
wheel, is raised up in one part of the revolution of the wheel; while,
by its own weight, it falls in another. This kind of motion is very
effectual in washing the cloth, while, at the same time, it does not
injure its strength. The plan, however, where economy of water is of any
importance, is very objectionable; because the wheel must move at by far
too great a velocity to act to advantage as a water-wheel.

[Illustration: 129 130]

The wash or dash-wheel, now driven by power in all good bleach and
print-works, is represented in _fig._ 129., upon the left side in a back
view, and upon the right side in a front view (the sketch being halved).
_Fig._ 130. is a ground plan.

_a a_ is the washing-wheel; _b b_ its shaft-ends; _c c_ their brass
bearings or plummer-blocks, supported upon the iron pillars _d d_. The
frame is made of strong beams of wood, _e e_, bound together by cross
bars with mortises. _f f_, two of the circular apertures, each leading
to a quadrantal compartment within the dash-wheel. In the back view (the
left-hand half of the figure) the brass grating _g g_, of a curvilinear
form, is seen, through which the jets of water are admitted into the
cavity of the wheel; _h h_, are the round orifices, through which the
foul water runs off, as each quadrant passes the lower part of its
revolution; _i_, a water-pipe, with a stop-cock for regulating the
washing-jets; _k k_, the lever for throwing the driving-crab _l_, or
coupling-box, into or out of geer with the shaft of the wheel. This
machine is so constructed, that the water-cock is opened or shut by the
same leverage which throws the wheel into or out of geer. _m_, a wheel,
fixed upon the round extremity of the shaft of the dash-wheel, which
works into the toothed pinion connected with the prime mover. When the
end of the lever _k_, whose fork embraces the coupling-box upon the
square part of the shaft, is pushed forwards or backwards, it shifts the
clutch into or out of geer with the toothed wheel _m_. In the latter
case, this wheel turns with its pinion without affecting the dash-wheel.
_n n_, holdfasts fixed upon the wooden frame, to which the boards _o o_
are attached, for preventing the water from being thrown about by the
centrifugal force.

The dash-wheel is generally from 6 to 7 feet in diameter, about 30
inches wide, and requires the power of about two horses to drive it.

From one to two pieces of calico may be done at once in each quadrantal
compartment, in the course of 8 or 10 minutes; hence, in a day of 13
hours, with two such wheels 1200 pieces of yard-wide goods may be
washed.

After the process of washing by the dash-wheel, the water is expressed
from the cloth by means of the squeezers already described.

_Bleaching of Linen._--Linen contains much more colouring matter than
cotton. The former loses nearly a third of its weight, while the latter
loses not more than a twentieth. The fibres of flax possess, in the
natural condition, a light gray, yellow, or blond colour. By the
operation of rotting, or, as it is commonly called, water-retting, which
is employed to enable the textile filaments to be separated from the
boon, or woody matter, the colour becomes darker, and, in consequence
probably of the putrefaction of the green matter of the bark, the
colouring substance appears. Hence, flax prepared without rotting is
much paler, and its colouring matter may be in a great measure removed
by washing with soap, leaving the filaments nearly white. Mr. James Lee
obtained a patent in 1812, as having discovered that the process of
steeping and dew-retting is unnecessary, and that flax and hemp will not
only dress, but will produce an equal if not greater quantity of more
durable fibre, when cleaned in the dry way. Mr. Lee stated that, when
hemp or flax plants are ripe, the farmer has nothing more to do than to
pull, spread, and dry them in the sun, and then to break them by proper
machinery. This promising improvement has apparently come to nought,
having been many years abandoned by the patentee himself, though he was
favoured with a special act of parliament, which permitted the
specification of his patent to remain sealed up for seven years,
contrary to the general practice in such cases.

The substance which gives steeped flax its peculiar tint is insoluble in
boiling water, in acids, and in alkalies; but it possesses the property
of dissolving in caustic or carbonated alkaline lyes, when it has
possessed the means of dehydrogenation by previous exposure to oxygen.
Hemp is, in this respect, analogous to flax. The bleaching of both
depends upon this action of oxygen, and upon the removal of the
acidified dye, by means of an alkali. This process is effected generally
by the influence of air in combination with light and moisture acting on
the linen cloth laid upon the grass: but chlorine will effect the same
object more expeditiously. In no case, however, is it possible to
acidify the colour completely at once, but there must be many alternate
exposures to oxygen or chlorine, and alkali, before the flax becomes
white. It is this circumstance alone which renders the bleaching of
linen an apparently complicated business.

Having made these preliminary observations with regard to the method of
applying the alkaline lyes used in bleaching linen cloth, I shall now
bring the whole into one point of view, by detailing the connection of
these processes, as carried on at a bleach-field, which has uniformly
been successful in returning the cloth of a good white, and has
otherwise given satisfaction to its employers; and I shall only remark,
that I by no means hold it up as the best process which may be employed,
as every experienced bleacher knows that processes must be varied, not
only according to existing circumstances, but also according to the
nature of the linens operated upon.

In order to avoid repetition, where washing is mentioned, it must always
be understood that the linen is taken to the wash-stocks or dash-wheel,
and washed well in them for some hours. This part of the work can never
be overdone; and on its being properly executed between every part of
the bucking, boiling, steeping in the chloride of lime solution, and
souring, not a little of the success of bleaching depends. By exposure
is meant, that the linen cloth is taken and spread upon the bleach-green
for four, six, or eight days, according as the routine of business calls
for the return of the cloth, in order to undergo further operations.

A parcel of goods consists of 360 pieces of those linens which are
called Britannias. Each piece is 35 yards long; and they weigh, on an
average, 10 lbs. each; the weight of the parcel is, in consequence,
about 3600 lbs. avoirdupois weight. The linens are first washed, and
then steeped in waste alkaline lye, as formerly described under these
processes; they then undergo the following operations:--

   1st, Bucked with 60 lbs. pearl-ashes, washed, exposed on the field.
   2d,  Ditto       80        ditto       ditto   ditto         ditto.
   3d,  Ditto       90      potashes      ditto   ditto         ditto.
   4th, Ditto       80        ditto       ditto   ditto         ditto.
   5th, Ditto       80      pearl-ashes,  ditto   ditto         ditto.
   6th, Ditto       50        ditto       ditto   ditto         ditto.
   7th, Ditto       70        ditto       ditto   ditto         ditto.
   8th, Ditto       70        ditto       ditto   ditto         ditto.
   9th, Soured one night in dilute sulphuric acid, washed.
  10th, Bucked with 50 lbs. pearl-ashes, washed, exposed on the field.
  11th, Immersed in the chloride of potash or lime 12 hours.
  12th, Boiled with 30 lbs. pearl ashes, washed, exposed on the field.
  13th, Ditto       30        ditto       ditto   ditto         ditto.
  14th, Soured, washed.

The linens are then taken to the rubbing-board, and well rubbed with a
strong lather of black soap, after which they are well washed in pure
spring water. At this period they are carefully examined, and those
which are fully bleached are laid aside to be blued, and made up for the
market; while those which are not fully white are returned to be boiled,
and steeped in the chloride of lime or potash; then soured, until they
are fully white.

By the above process, 690 lbs. weight of alkali is taken to bleach 360
pieces of linen, each piece consisting of 35 yards in length; so that
the expenditure of alkali would be somewhat less than 2 lbs. for each
piece, were it not that some parts of the linens are not fully whitened,
as above noted. Two pounds of alkali may therefore be stated as the
average quantity employed for bleaching each piece of goods.

The method of bleaching linens in Ireland is similar to the foregoing;
any alteration in the process depending upon the judgment of the
bleacher in increasing or diminishing the quantity of alkali used. But
it is common, at most bleach-fields, to steep the linens in the chloride
of lime or potash at an early stage of the process, or after the goods
have undergone the fifth or sixth operation of bucking. By this means
those parts of the flax which are most difficult to bleach are more
easily acted upon by the alkali; and, as before noticed, souring early
in very dilute sulphuric acid, assists greatly in forwarding the
whitening of the linens. Mr. Grimshaw, calico-printer, near Belfast, was
the first who recommended early souring, which has since been very
generally adopted.

_The bleaching of Silk._--Silk in its raw state, as spun by the worm, is
either white or yellow of various shades, and is covered with a varnish,
which gives it stiffness and a degree of elasticity. For the greater
number of purposes to which silk is applied, it must be deprived of this
native covering, which was long considered to be a sort of gum. The
operation by which this colouring matter is removed is called scouring,
cleansing, or boiling. A great many different processes have been
proposed for freeing the silk fibres from all foreign impurities, and
for giving it the utmost whiteness, lustre, and pliancy; but none of the
new plans has superseded, with any advantage, the one practised of old,
which consists essentially in steeping the silk in a warm solution of
soap; a circumstance placed beyond all doubt by the interesting
experiments of M. Roard. The alkalies, or alkaline salts, act in a
marked manner upon the varnish of silk, and effect its complete
solution; the prolonged agency of boiling water, alone answers the same
purpose; but nothing agrees so well with the nature of silk, and
preserves its brilliancy and suppleness so perfectly, as a rapid boil
with soap-water. It would appear, however, that the Chinese do not
employ this method, but something that is preferable. Probably the
superior beauty of their white silk may be owing to the superiority of
the raw material.

The most ancient method of scouring silk consists of three operations.
For the first, or the _ungumming_, thirty per cent. of soap is first of
all dissolved in clean river water by a boiling heat; then the
temperature is lowered by the addition of a little cold water, by
withdrawing the fire, or at least by damping it. The hanks of silk
suspended upon horizontal poles over the boiler, are now plunged into
the soapy solution, kept at a heat somewhat under ebullition, which is
an essential point; for if hotter, the soap would attack the substance
of the silk, and not only dissolve a portion of it, but deprive the
whole of its lustre. The portions of the hanks plunged in the bath get
scoured by degrees; the varnish and the colouring matter come away, and
the silk assumes its proper whiteness and pliancy. Whenever this point
is attained, the hanks are turned round upon the poles, so that the
portion formerly in the air may be also subjected to the bath. As soon
as the whole is completely ungummed, they are taken out, wrung by the
peg, and shaken out; after which, the next step, called the _boil_, is
commenced. Into bags of coarse canvass, called _pockets_, about 25 lbs.
or 35 lbs. of ungummed silk are enclosed, and put into a similar bath
with the preceding, but with a smaller proportion of soap, which may
therefore be raised to the boiling point without any danger of
destroying the silk. The ebullition is to be kept up for an hour and a
half, during which time the bags must be frequently stirred, lest those
near the bottom should suffer an undue degree of heat. The silk
experiences in these two operations a loss of about 25 per cent. of its
weight.

The third and last scouring operation is intended to give the silk a
slight tinge, which renders the white more agreeable, and better
adapted to its various uses in trade. In this way we distinguish the
China white, which has a faint cast of red, the silver white, the azure
white, and the thread white. To produce these different shades, we begin
by preparing a soap-water so strong as to lather by agitation; we then
add to it, for the China white, a little annotto, mixing it carefully
in; and then passing the silk properly through it, till it has acquired
the wished for tint. As to the other shades, we need only azure them
more or less with a fine indigo, which has been previously washed
several times in hot water, and reduced to powder in a mortar. It is
then diffused through boiling water, allowed to settle for a few
minutes, and the supernatant liquid, which contains only the finer
particles, is added to the soap bath, in such proportion as may be
requisite. The silk, on being taken out of this bath, must be wrung
well, and stretched upon perches to dry; after which it is introduced
into the sulphuring chamber, if it is to be made use of in the white
state. At Lyons, however, no soap is employed at the third operation:
after the boil, the silk is washed, sulphured, and azured, by passing
through very clear river water properly blued.

The silks intended for the manufacture of blonds and gauzes are not
subjected to the ordinary scouring process, because it is essential, in
these cases, for them to preserve their natural stiffness. We must
therefore select the raw silk of China, or the whitest raw silks of
other countries; steep them, rince them in a bath of pure water, or in
one containing a little soap; wring them, expose them to the vapour of
sulphur, and then pass them through the azure water. Sometimes this
process is repeated.

Before the memoir of M. Roard appeared, extremely vague ideas were
entertained about the composition of the native varnish of silk. He has
shown that this substance, so far from being of a gummy nature, as had
been believed, may be rather compared to bees’ wax, with a species of
oil, and a colouring matter, which exists only in raw silks. It is
contained in them to the amount of from 23 to 24 per cent., and forms
the portion of weight which is lost in the _ungumming_. It possesses,
however, some of the properties of vegetable gums, though it differs
essentially as to others. In a dry mass, it is friable and has a
vitreous fracture; it is soluble in water, and affords a solution which
lathers like soap; but when thrown upon burning coals, it does not
soften like gum, but burns with the exhalation of a fetid odour. Its
solution, when left exposed to the open air, at first of a golden
yellow, becomes soon greenish, and ere long putrefies, as a solution of
animal matter would do in similar circumstances. M. Roard assures us
that the city of Lyons alone could furnish several thousand quintals of
this substance _per annum_, were it applicable to any useful purpose.

The yellow varnish is of a resinous nature, altogether insoluble in
water, very soluble in alcohol, and contains a little volatile oil,
which gives it a rank smell. The colour of this resin is easily
dissipated, either by exposure to the sun or by the action of chlorine:
it forms about one fifty-fifth of its weight.

Bees’ wax exists also in all the sorts of silk, even in that of China;
but the whiter the filaments, the less wax do they contain.

M. Roard has observed that, if the silk be exposed to the soap baths for
some time after it has been stripped of its foreign matters, it begins
to lose body, and has its valuable qualities impaired. It becomes dull,
stiff, and coloured in consequence of the solution more or less
considerable of its substance; a solution which takes place in all
liquids, and even in boiling water. It is for this reason that silks
cannot be alumed with heat; and that they lose some of their lustre in
being dyed brown, a colour which requires a boiling hot bath. The best
mode, therefore, of avoiding these inconveniences, is to boil the silks
in the soap-bath no longer than is absolutely necessary for the scouring
process, and to expose them in the various dyeing operations to as
moderate temperature as may be requisite to communicate the colour. When
silks are to be dyed, much less soap should be used in the cleansing,
and very little for the dark colours. According to M. Roard, raw silks,
white or yellow, may be completely scoured, in one hour, with 15 lbs. of
water for one of silk, and a suitable proportion of soap. The soap and
the silk should be put into the bath half an hour before its ebullition,
and the latter should be turned about frequently. The dull silks, in
which the varnish has already undergone some alteration, never acquire a
fine white until they are exposed to sulphureous acid gas. Exposure to
light has also a very good effect in whitening silks, and is had
recourse to, it is said, with advantage by the Chinese.

Carbonate of soda has been proposed to be used instead of soap in
scouring silk, but it has never come into use. The Abbé Collomb, in
1785, scoured silk by eight hours’ boiling in simple water, and he found
the silks bleached in this way to be stronger than by soap, but they are
not nearly so white. A patent has been taken out in England for
bleaching them by steam, of which an account will be found under the
article SILK.

It appears that the Chinese do not use soap in producing those fine
white silks which are imported into Europe. Michel de Grubbens who
resided long at Canton, saw and practised himself the operation there,
which he published in the Memoirs of the Academy of Stockholm in 1803.
It consists in preparing the silk with a species of white beans, smaller
than the Turkey beans, with some wheat flour, common salt, and water.
The proportions are 5 parts of beans, 5 of salt, 6 of flour, and 25 of
water, to form this vegetable bath. The beans must be previously washed.
It is difficult to discover what chemical action can occur between that
decoction and the varnish of raw silk; possibly some acid may be
developed, which may soften the gummy matter, and facilitate its
separation.

Baumé contrived a process which does not appear to have received the
sanction of experience, but which may put us in the right way. He
macerates the yellow raw silk in a mixture of alcohol at 36° (sp. gr.
0·837) and one thirty-second part of pure muriatic acid. At the end of
forty-eight hours, it is as white as possible, and the more so, the
better the quality of the silk. The loss which it suffers in this
menstruum is only one fortieth; showing that nothing but the colouring
matter is abstracted. The expense of this menstruum is the great
obstacle to Baumé’s process. The alcohol, however, might be in a very
great measure recovered, by saturating the acid with chalk, and
redistillation.

_Bleaching of Wool._--Wool, like the preceding fibrous matter, is
covered with a peculiar varnish, which impairs its qualities, and
prevents it from being employed in the raw state for the purposes to
which it is well adapted when it is scoured. The English give the name
_yolk_, and the French _suint_, to that native coat: it is a fatty
unctuous matter, of a strong smell, which apparently has its chief
origin in the cutaneous perspiration of the sheep; but which, by the
agency of external bodies, may have undergone some changes which modify
its constitution. It results from the experiments of M. Vauquelin, that
the _yolk_ is composed of several substances; namely, 1. a soap with
basis of potash, which constitutes the greater part of it; 2. of a
notable quantity of acetate of potash; 3. of a small quantity of
carbonate, and a trace of muriate, of potash; 4. of a little lime in an
unknown state of combination; 5. of a species of sebaceous matter, and
an animal substance to which the odour is due. There are several other
accidental matters present on sheep’s wool.

The proportion of yolk is variable in different kinds of wool, but in
general it is more abundant the finer the staple; the loss by scouring
being 45 per cent. for the finest wools, and 35 per cent. for the
coarse.

The yolk, on account of its soapy nature, dissolves readily in water,
with the exception of a little free fatty matter, which easily separates
from the filaments, and remains floating in the liquor. It would thence
appear sufficient to expose the wools to simple washing in a stream of
water; yet experience shows that this method never answers so well as
that usually adopted, which consists in steeping the wool for some time
in simple warm water, or in warm water mixed with a fourth of stale
urine. From 15 to 20 minutes of contact are sufficient in this case, if
we heat the bath as warm as the hand can bear it, and stir it well with
a rod. At the end of this time the wool may be taken out, set to drain,
then placed in large baskets, in order to be completely rinsed in a
stream of water.

It is generally supposed that putrid urine acts on the wool by the
ammonia which it contains, and that this serves to saponify the
remainder of the fatty matter not combined with the potash. M. Vauquelin
is not of this opinion, because he found that wool steeped in water,
with sal ammoniac and quick lime, is not better scoured than an equal
quantity of wool treated with mere water. He was hence led to conclude
that the good effects of putrefied urine might be ascribed to any thing
else besides the ammonia, and probably to the urea. Fresh urine contains
a free acid, which, by decomposing the potash soap of the yolk,
counteracts the scouring operation.

If wools are better scoured in a small quantity of water than in a great
stream, we can conceive that this circumstance must depend upon the
nature of the yolk which, in a concentrated solution, acts like a
saponaceous compound, and thus contributes to remove the free fatty
particles which adhere to the filaments. It should also be observed that
too long a continuance of the wool in the yolk water, hurts its quality
very much, by weakening its cohesion, causing the filaments to swell,
and even to split. It is said then to have lost its _nerve_. Another
circumstance in the scouring of wool, that should always be attended to,
is never to work the filaments together to such a degree as to occasion
their felting; but in agitating we must merely push them slowly round in
the vessel, or press them gently under the feet. Were it at all felted,
it would neither card nor spin well.

As the heat of boiling water is apt to decompose woollen fibres, we
should be careful never to raise the temperature of the scouring bath to
near this point, nor, in fact, to exceed 140° F. Some authors recommend
the use of alkaline or soapy baths for scouring wool, but practical
people do not deviate from the method above described.

When the washing is completed, all the wool which is to be sent white
into the market, must be exposed to the action of sulphurous acid,
either in a liquid or a gaseous state. In the latter case, sulphur is
burned in a close chamber, in which the wools are hung up or spread out;
in the former, the wools are plunged into water, moderately impregnated
with the acid. (See SULPHURING.) Exposure on the grass may also
contribute to the bleaching of wool. Some fraudulent dealers are accused
of dipping wools in butter-milk, or chalk and water, in order to whiten
them and increase their weight.

Wool is sometimes whitened in the fleece, and sometimes in the state of
yarn; the latter affording the best means of operating. It has been
observed that the wool cut from certain parts of the sheep, especially
from the groins, never bleaches well.

After sulphuring, the wool has a harsh crispy feel, which may be removed
by a weak soap bath. To this also the wool comber has recourse when he
wishes to cleanse and whiten his wools to the utmost. He generally uses
a soft or potash soap, and after the wool is well soaked in the warm
soap bath, with gentle pressure he wrings it well with the help of a
hook, fixed at the end of his washing tub, and hangs it up to dry.

_Bleaching of rags, and paste for paper making._--After the rags are
reduced to what is called half stuff, they should have the greater part
of the floating water run off, leaving just enough to form a stir-about
mass. Into this a clear solution of chloride of lime should be poured,
of such a strength as is suited to the colour of the rags, which should
have been previously sorted; and the engine is kept going so as to churn
the rags with the bleaching agent. After an hour, the water may be
returned upon the engine, and the washing of the paper resumed. From two
to four pounds of good chloride of lime are reckoned sufficient to
bleach one hundred weight of rags.

When the rags consist of dyed or printed cottons, after being well
washed and reduced to half stuff, they should be put into a large cask
or butt, supported horizontally by iron axles upon cradle bearings, so
that it may be made to revolve like a barrel-churn. For each hundred
weight of the coloured rags, take a solution containing from four to
eight pounds of chloride of lime; add it to the liquid mixture in the
butt along with half a pound of sulphuric acid for every pound of the
chloride; and after inserting the bung, or rather the square valve, set
the vessel in slow revolution backwards and forwards. In a short time
the rags will be colourless. The rags and paper paste ought to be very
well washed, to expel all the chlorine, and perhaps a little muriatic
acid might be used with advantage to dissolve out all the calcareous
matter, a portion of which is apt to remain in the paper, and to operate
injuriously upon both the pens and the ink. Some of the French paper
manufacturers bleach the paste with chlorine gas. Paper prepared from
such paste, well washed, is not apt to give a brown tint to maps, as
that carelessly bleached with chloride of lime is known to do.


BLENDE. (_Fr. and Germ._) Sulphuret of zinc, so named from the German
_blenden_ to dazzle, on account of its glistening aspect. It is called
black jack from its usual colour. Its lustre is pearly adamantine. Spec.
gravity from 3·7 to 4·2. It contains frequently iron, copper, arsenic,
cadmium and silver, all associated with sulphur. It is worked up partly
into metallic zinc, and partly into the sulphate of zinc, or white
vitriol. It consists of 66·72 zinc, and 33·28 sulphur; being nearly by
weight as two to one. See ZINC.


BLOCK MANUFACTURE. Though the making of ships’ blocks belongs rather to
a dictionary of engineering than of manufactures, it may be expected
that I should give some account of the automatic machinery for making
blocks, so admirably devised and mounted by M. I. Brunel, Esq. for the
British navy, in the dock-yard of Portsmouth.

The series of machines and operations are as follows:--

1. _The straight cross cutting saw._--The log is placed horizontally on
a very low bench which is continued through the window of the mill into
the yard. The saw is exactly over the place where the log is to be
divided. It is let down, and suffered to rest with its teeth upon the
log, the back still being in the cleft of the guide. The crank being set
in motion, the saw reciprocates backwards and forwards with exactly the
same motion as if worked by a carpenter, and quickly cuts through the
tree. When it first begins to cut, its back is in the cleft in the
guide, and this causes it to move in a straight line; but before it gets
out of the guide, it is so deep in the wood as to guide itself: for in
cutting across the grain of the wood, it has no tendency to be diverted
from its true line by the irregular grain. When the saw has descended
through the tree, its handle is caught in a fixed stop, to prevent its
cutting the bench. The machine is thrown out of geer, the attendant
lifts up the saw by a rope, removes the block cut off, and advances the
tree to receive a fresh cut.

2. _The circular cross-cutting saw._--This saw possesses universal
motion; but the axis is always parallel to itself, and the saw in the
same plane. It can be readily raised or lowered, by inclining the upper
frame on its axis; and to move it sidewise, the saw frame must swing
sidewise on its joints, which connect it with the upper frame. These
movements are effected by two winches, each furnished with a pair of
equal pinions, working a pair of racks fixed upon two long poles. The
spindles of these winches are fixed in two vertical posts, which
support the axis of the upper frame. One of these pairs of poles is
jointed to the extreme end of the upper frame; therefore by turning the
handle belonging to them, the frame and saw is elevated or depressed; in
like manner, the other pair is attached to the lower part of the saw
frame, so that the saw can be moved sidewise by means of their handles,
which then swing the saw from its vertical position.

These two handles give the attendant a complete command of the saw,
which we suppose to be in rapid motion, the tree being brought forward
and properly fixed. By one handle, he draws the saw against one side of
the tree, which is thus cut into, (perhaps half through); now, by the
other handle, he raises the saw up, and by the first-mentioned handle he
draws it across the top of the tree, and cuts it half through from the
upper side; he then depresses the saw and cuts half through from the
next side; and lastly a trifling cut of the saw, at the lower side,
completely divides the tree, which is then advanced to take another cut.

_The great reciprocating saw_ is on the same principle as the saw mill
in common use in America.

3. _The circular ripping saw_ is a thin circular plate of steel, with
teeth similar to those of a pit saw, formed in its periphery. It is
fixed to a spindle placed horizontally, at a small distance beneath the
surface of a bench or table, so that the saw projects through a crevice
a few inches above the bench. The spindle being supported in proper
collars, has a rapid rotatory motion communicated to it by a pulley on
the opposite end, round which an endless strap is passed from a drum
placed overhead in the mill. The block cut by the preceding machine,
from the end of the tree, is placed with one of the sides flat upon the
bench, and thus slides forward against the revolving saw which cuts the
wood with a rapidity incredible to any one who has not seen these or
similar machines.

[Illustration: 131 132]

4. _Boring machine._--The blocks, prepared by the foregoing saws, are
placed in the machine represented in _fig._ 131. This machine has an
iron frame, A A, with three legs, beneath which the block is introduced,
and the screw near B being forced down upon it, confines it precisely in
the proper spot to receive the borers D and E. This spot is determined
by a piece of metal fixed perpendicularly just beneath the point of the
borer E, shown separately on the ground at X; this piece of metal
adjusts the position for the borer D, and its height is regulated by
resting on the head of the screw _x_, which fastens the piece X down to
the frame. The sides of the block are kept in a parallel position, by
being applied against the heads of three screws tapped into the double
leg of the frame A. The borer D is adapted to bore the hole for the
centre pin in a direction exactly perpendicular to the surface resting
against the three screws; the other, at E, perforates the holes for the
commencement of the sheave holes. Both borers are constructed in nearly
the same manner; they are screwed upon the ends of small mandrels,
mounted in frames similar to a lathe. These frames, G and H, are fitted
with sliders upon the angular edges of the flat broad bars, I and K. The
former of these is screwed fast to the frame; the latter is fixed upon a
frame of its own, moving on the centre screws, at L L, beneath the
principal frame of the machine. By this means the borer E can be moved
within certain limits, so as to bore holes in different positions. These
limits are determined by two screws, one of which is seen at _a_; the
other being on the opposite side is invisible. They are tapped through
fixed pieces projecting up from the frame. A projecting piece of metal,
from the under side of the slider K of the borer E, stops against the
ends of these screws, to limit the excursion of the borer. The frames
for both borers are brought up towards the block by means of levers M
and N. These are centered on a pin, at the opposite sides of the frame
of the machine, and have oblong grooves through them which receive screw
pins, fixed into the frames G and H, beneath the pulleys P P, which give
motion to the spindles.

5. _The mortising machine_ is a beautiful piece of mechanism, but too
complicated for description within the limits prescribed to this
article.

6. _The corner saw_, _fig._ 132., consists of a mandrel, mounted in a
frame A, and, carrying a circular saw L upon the extreme end of it. This
mandrel and its frame being exactly similar to those at G and H _fig._
131., does not require a separate view, although it is hid behind the
saw, except the end of the screw, marked A. This frame is screwed down
upon the frame B B of the machine, which is supported upon four columns.
C C, D D, is an inclined bench, or a kind of trough, in which a block is
laid, as at E, being supported on its edge by the plane C C of this
bench, and its end kept up to its position by the other part of the
bench D D.

By sliding the block along this bench, it is applied to the saw, which
cuts off its angles, as is evident from the figure, and prepares it for
the shaping engine. All the four angles are cut off in succession, by
applying its different sides to the trough or bench. In the figure, two
of them are drawn as being cut, and the third is just marked by the saw.
This machine is readily adapted to different sizes of blocks, by the
simple expedient of laying pieces of wood of different thickness against
the plane D D, so as to fill it up, and keep the block nearer to or
farther from the saw; for all the blocks are required to be cut at the
same angle, though, of course, a larger piece is to be cut from large
than from small blocks. The block reduced to the state of E is now taken
to

7. _The shaping machine._--A great deal of the apparent complication of
this figure arises from the iron cage, which is provided to defend the
workmen, lest the blocks, which are revolving in the circles, or chuck,
with an immense velocity, should be loosened by the action of the tool,
and fly out by their centrifugal force. Without this provision, the
consequences of such an accident would be dreadful, as the blocks would
be projected in all directions, with an inconceivable force.

8. _The scoring engine_ receives two blocks, as they come from the
shaping engine, and forms the groove round their longest diameters for
the reception of their ropes or straps, as represented in the two snatch
blocks and double block, under _figs._ 131, 132.

[Illustration: 133]

A, B, _fig._ 133., represent the above two blocks, each held between two
small pillars _a_, (the other pillar is hid behind the block) fixed in a
strong plate D, and pressed against the pillars by a screw _b_, which
acts on a clamp _d_. Over the blocks a pair of circular planes or
cutters E E, are situated, both being fixed on the same spindle, which
is turned by a pulley in the middle of it. The spindle is fitted in a
frame F F, moving in centres at _e e_, so as to rise and fall when
moved by a handle _f_. This brings the cutters down upon the blocks; and
the depth to which they can cut is regulated by a curved shape _g_,
fixed by screws upon the plate D, between the blocks. Upon this rests a
curved piece of metal _h_, fixed to the frame F, and inclosing, but not
touching, the pulley. To admit the cutters to traverse the whole length
of the blocks, the plate D, (or rather a frame beneath it,) is sustained
between the points of two centres. Screws are seen at _l_, on these
centres. The frame inclines when the handle L is depressed. At M is a
lever, with a weight at the end of it, counterbalancing the weight of
the blocks, and plate D, all which are above the centre on which they
move. The frame F is also provided with a counterpoise to balance the
cutters, &c. The cutters E E are circular wheels of brass, with round
edges. Each has two notches in its circumference, at opposite sides; and
in these notches chisels are fixed by screws, to project beyond the rim
of the wheel, in the manner of a plane iron before its face.

This machine is used as follows:--In order to fix the block, it is
pressed between the two pins (only one of which at _a_, can be seen in
this view), and the clamp _d_, screwed up against it, so as just to hold
the block, but no more. The clamp has two claws, as is seen in the
figure, each furnished with a ring entering the double prints previously
made, in the end of the block. These rings are partly cut away, leaving
only such a segment of each as will just retain the block, and the metal
between them is taken out to admit the cutter to operate between them,
or nearly so. In putting the blocks into this machine, the workman
applies the double prints to the ends of the claws of the clamps, but
takes care that the blocks are higher between the pins _a_ than they
should be; he then takes the handle _f_, and by it presses the cutters E
E, (which we suppose are standing still,) down upon the blocks,
depressing them between their pins at the same time, till the descent of
the cutters is stopped by the piece _h_ resting on the shape _g_. He now
turns the screws _b b_, to fix the blocks tight. The cutters being put
in motion cut the scores, which will be plainly seen by the mode of
adjustment just described, to be of no depth at the pin-hole; but by
depressing the handle L, so as to incline the blocks, and keeping the
cutters down upon their shape _g_, by the handle _f_, they will cut any
depth towards the ends of the blocks, which the shape _g_ admits.

By this means one quarter of the score is formed; the other is done by
turning both blocks together half round in this manner. The centres _l_
are not fitted into the plate D itself, but into a frame seen at R
beneath the plate, which is connected with it by a centre pin, exactly
midway between the two blocks A B. A spring catch, the end of which is
seen at _r_, confines them together; when this catch is pressed back,
the plate D can be turned about upon its centre pin, so as to change the
blocks, end for end, and bring the unscored quarters (_i. e._ over the
clamps) beneath the cutters; the workman taking the handles _f_ and L,
one in each hand, and pressing them down, cuts out the second quarter.
This might have been effected by simply lifting up the handle L; but in
that case the cutter would have struck against the grain of the wood, so
as to cut rather roughly; but by this ingenious device of reversing the
blocks, it always cuts clean and smooth, in the direction of the grain.
The third and fourth quarters of the score are cut by turning the other
sides of the blocks upwards, and repeating the above operation. The
shape _g_ can be removed, and another put in its place, for different
sizes and curves of block; but the same pins _a_, and holding clamps
_d_, will suit many different sizes.

By these machines the shells of the blocks are completely formed, and
they are next polished and finished by hand labour; but as this is
performed by tools and methods which are well known, it is needless to
enter into any explanation: the finishing required being only a
smoothing of the surfaces. The machines cut so perfectly true as to
require no wood to be removed in the finishing; but as they cut without
regard to the irregularity of the grain, knots, &c., it happens that
many parts are not so smooth as might be wished, and for this purpose
manual labour alone can be employed.

The lignum vitæ for the sheaves of the blocks, is cut across the grain
of the wood by two cross cutting saws, a circular and straight saw, as
before mentioned. These machines do not essentially differ in their
principle from the great cross cutting saws we have described, except
that the wood revolves while it is cutting, so that a small saw will
reach the centre of a large tree, and at the same time cut it truly
flat. The limits prescribed for our plates will not admit of giving
drawings of these machines, and the idea which could be derived from a
verbal description would not be materially different from the cross
cutting saws before mentioned. These machines cut off their plates for
the end of the tree, which are exactly the thickness for the intended
sheave. These pieces are of an irregular figure, and must be rounded and
centered in the crown saw.

[Illustration: 134]

9. _The crown saw_ is represented in _fig._ 134., where A is a pulley
revolving by means of an endless strap. It has the crown or trepan saw
_a_ fixed to it, by a screw cut within the piece, upon which the saw is
fixed, and which gives the ring or hoop of the saw sufficient stability
to perform its office. Both the pulleys and saw revolve together upon a
truly cylindrical tube _b_, which is stationary, being attached by a
flaunch _c_ to a fixed puppet B, and on this tube as an axis the saw and
pulley turn, and may be slid endwise by a collar fitted round the centre
piece of the pulley, and having two iron rods (only one of which can be
seen at _d_ in the figure), passing through holes made through the
flaunch and puppet B. When the saw is drawn back upon its central tube,
the end of the latter projects beyond the teeth of the saw. It is by
means of this fixed ring or tube within the saw, that the piece of wood
_e_ is supported during the operation of sawing, being pressed forcibly
against it by a screw D, acting through a puppet fixed to the frame of
the machine. At the end of this screw is a cup or bason which applies
itself to the piece of wood, so as to form a kind of vice, one side
being the end of the fixed tube, the other the cup at the end of the
screw D. Within the tube _b_ is a collar for supporting a central axis,
which is perfectly cylindrical. The other end of this axis, (seen at
_f_,) turns in a collar of the fixed puppet E. The central axis has a
pulley F, fixed on it, and giving it motion by a strap similar to the
other. Close to the latter pulley a collar _g_ is fitted on the centre
piece of the pulley, so as to slip round freely, but at the same time
confined to move endways with the pulley and its collar. This collar
receives the ends of the two iron rods _d_. The opposite ends of these
rods are, as above mentioned, connected by a similar collar, with the
pulley A of the saw _a_. By this connection, both the centre bit, which
is screwed into the end of the central axis _f_, and the saw sliding
upon the fixed tube _b_, are brought forward to the wood at the same
time, both being in rapid motion by their respective pulleys.

10. _The Coaking Engine._--This ingenious piece of machinery is used to
cut the three semicircular holes which surround the hole bored by the
crown saw, so as to produce a cavity in the centre of the disc.

11. _Face-turning Lathe._--The sheave is fixed against a flat chuck at
the end of a mandrel, by an universal chuck, similar to that in the
coaking engine, except that the centre pin, instead of having a nut, is
tapped into the flat chuck, and turned by a screw-driver.


BLOOD. (_Sang_, Fr.; _Blut_, Germ.) The liquid which circulates in the
arteries and veins of animals; bright red in the former and purple in
the latter, among all the tribes whose temperature is considerably
higher than that of the atmosphere. It consists 1. of a colourless
transparent solution of several substances in water; and 2. of red,
undissolved particles diffused through that solution. Its specific
gravity varies with the nature and health of the animal; being from
1·0527 to 1·0570 at 60° F. It has a saline sub-nauseous taste, and a
smell peculiar to each animal. When fresh drawn from the vessels, it
rapidly coagulates into a gelatinous mass, called the clot, cruor, or
crassamentum, from which after some time, a pale yellow fluid, passing
into yellowish green, oozes forth, called the _serum_. If the warm blood
be stirred with a bundle of twigs, as it flows from the veins, the
fibrine concretes, and forms long fibres and knots, while it retains its
usual appearance in other respects. The clot contains fibrine and
colouring matter in various proportions. Berzelius found in 100 parts of
the dried clot of blood, 35 parts of fibrine, 58 of colouring matter;
1·3 of carbonate of soda; 4 of an animal matter soluble in water, along
with some salts and fat. The specific gravity of the serum varies from
1·027 to 1·029. It forms about three fourths of the weight of the blood,
has an alkaline reaction, coagulates at 167° F. into a gelatinous mass,
and has for its leading constituent _albumen_ to the amount of 8 per
cent. besides fat, potash, soda, and salts of these bases. Blood does
not seem to contain any gelatine.

The red colouring matter called _hematine_, may be obtained from the
cruor by washing with cold water and filtering.

Blood was at one time largely employed for clarifying syrup, but it is
very sparingly used by the sugar refiners in Great Britain of the
present day. It may be dried by evaporation at a heat of 130° or 140°,
and in this state has been transported to the colonies for purifying
cane juice. It is an ingredient in certain adhesive cements, coarse
pigments for protecting walls from the weather, for making animal
charcoal in the Prussian blue works, and by an after process, a
decolouring carbon. It is used in some Turkey red dye-works. Blood is a
powerful manure.


BLOWING MACHINE. See IRON, METALLURGY, VENTILATION.


BLOWPIPE. (_Chalumeau_, Fr.; _Lothröhre_, Germ.) Jewellers,
mineralogists, chemists, enamellers, &c. make frequent use of a tube,
usually bent near the end, terminated with a finely pointed nozzle, for
blowing through the flame of a lamp, candle, or gas-jet, and producing
thereby a small conical flame possessing a very intense heat.
Modifications of blow pipes are made with jets of hydrogen, oxygen, or
the two gases mixed in due proportions.


BLUE DYES. (_Teint_, Germ. See ENAMEL.) The materials employed for this
purpose are indigo, Prussian blue, logwood, bilberry, (_vaccinium
myrtillus_,) elder berries, (_sambucus nigra_,) mulberries, privet
berries, (_ligustrum vulgare_,) and some other berries whose juice
becomes blue by the addition of a small portion of alkali, or of the
salts of copper. For dyeing with the first three articles, see them in
their alphabetical places. I shall here describe the other or minor blue
dyes.

To dye blue with such berries as the above, we boil one pound of them in
water, adding one ounce of alum, of copperas, and of blue vitriol, to
the decoction, or in their stead equal parts of verdegris and tartar,
and pass the stuffs a sufficient time through the liquor. When an iron
mordant alone is employed, a steel blue tint is obtained; and when a tin
one, a blue with a violet cast. The privet berries which have been
employed as sap colours by the card painters, may be extensively used in
the dyeing of silk. The berries of the African night-shade (_solanum
guineense_) have been of late years considerably applied to silk on the
continent in producing various shades of blue, violet, red, brown, &c.
but particularly violet. With alkalis and acids these berries have the
same habitudes as bilberries; the former turning them green, the latter
red. They usually come from Italy compressed in a dry cake, and are
infused in hot water. The infusion is merely filtered, and then employed
without any mordant, for dyeing silk, being kept at a warm temperature
by surrounding the bath vessel with hot water. The goods must be winced
for six hours through it in order to be saturated with colour; then they
are to be rinsed in running water and dried. One pound of silk requires
a pound and a half of the berry cake. In the residuary bath, other tints
of blue may be given. Sometimes the dyed silk is finished by running it
through a weak alum water. A colour approaching to indigo in permanence,
but which differs from it in being soluble in alkalis, though incapable
of similar disoxidizement, is the _gardenia genipa_ and _aculeata_ of
South America whose colourless juice becomes dark blue with contact of
air; and dyes stuffs, the skin, and nails, of an unchangeable deep blue
colour, but the juice must be applied in the colourless state.


BLUE PIGMENTS. Several metallic compounds possess a blue colour;
especially those of iron, cobalt, and molybdenum. The metallic pigments,
little if at all employed, but which may be found useful in particular
cases, are the molybdate of mercury, the hydro-sulphuret of tungsten,
the prussiate of tungsten, the molybdate of tin, the oxide of copper
darkened with ammonia, the silicate of copper, and a fine violet colour
formed from manganese and molybdenum. The blues of vegetable origin, in
common use, are indigo, litmus, and blue cakes. The blue pigments of a
metallic nature found in commerce are the following: _Prussian blue_;
_mountain blue_, a carbonate of copper mixed with more or less earthy
matter; _Bremen blue_, or _verditer_, a greenish blue colour obtained
from copper mixed with chalk or lime; _iron blue_, phosphate of iron,
little employed; _cobalt blue_, a colour obtained by calcining a salt of
cobalt with alumina or oxide of tin; _smalt_, a glass coloured with
cobalt and ground to a fine powder; _charcoal blue_, a deep shade
obtained by triturating carbonized vine stalks with an equal weight of
potash in a crucible till the mixture ceases to swell, then pouring it
upon a slab, putting it into water and saturating the alkali with
sulphuric acid. The liquor becomes blue, and lets fall a dark blue
precipitate, which becomes of a brilliant blue colour when heated.

Molybdenum blue is a combination of this metal, and oxide of tin or
phosphate of lime. It is employed both as a paint, and an enamel colour.
A blue may also be obtained by putting into molybdic acid, (made by
digesting sulphuret of molybdenum with nitric acid,) some filings of
tin, and a little muriatic acid. The tin deoxidizes the molybdic acid to
a certain degree, and converts it into the molybdous, which when
evaporated and heated with alumina recently precipitated, forms this
blue pigment. _Ultramarine_ is a beautiful blue pigment, which see.


BLUE VITRIOL; sulphate of copper.


BOMBAZINE. A worsted stuff, sometimes mixed with silk.


BONES. (_Os_, Fr.; _Knochen_, Germ.) They form the frame work of animal
bodies, commonly called the skeleton; upon which the soft parts are
suspended, or in which they are enclosed. Bones are invested with a
membrane styled the periosteum, which is composed of a dense tissue
affording glue; whence it is convertible into jelly, by ebullition with
water. Bones are not equally compact throughout their whole substance;
the long ones have tubes in their centres lined with a kind of
periosteum, of more importance to the life of the bones than even their
external coat. The flat, as well as the short and thick bones, exhibit
upon their surface an osseous mass of a dense nature, while their
interior presents a cavity divided into small cellules by their bony
partitions.

In reference to the composition of bones, we have to consider two
principal constituents; the living portion or the osseous cartilage, and
the inorganic or the earthy salts of the bones.

The osseous cartilage is obtained by suspending bones in a large vessel
full of dilute muriatic acid, and leaving it in a cool place at about
50° Fahr. for example. The acid dissolves the earthy salts of the bones
without perceptibly attacking the cartilage, which, at the end of a
short time, becomes soft and translucid, retaining the shape of the
bones; whenever the acid is saturated, before it has dissolved all the
earthy salts it should be renewed. The cartilage is to be next suspended
in cold water, which is to be frequently changed till it has removed all
the acidity. By drying, the cartilage shrinks a little, and assumes a
darker hue, but without losing its translucency. It becomes, at the same
time, hard and susceptible of breaking when bent, but it possesses great
strength.

This cartilage is composed entirely of a tissue passing into gelatine.
By boiling with water, it is very readily convertible into a glue, which
passes clear and colourless through the filter, leaving only a small
portion of fibrous matter insoluble by further boiling. This matter is
produced by the vessels which penetrate the cartilage, and carry
nourishment to the bone. We may observe all these phenomena in a very
instructive manner, by macerating a bone in dilute muriatic acid, till
it has lost about the half of its salts; then washing it with cold
water, next pouring boiling water upon it, leaving the whole in repose
for 24 hours, at a temperature a few degrees below 212° Fahr.

The cartilage, which has been stripped of its earthy salts dissolves,
but the small vessels which issue from the undecomposed portion of the
bone remain under the form of white plumes, if the water has received no
movement capable of crushing or breaking them. We may then easily
recognise them with a lens, but the slightest touch tears them, and
makes them fall to the bottom of the vessel in the form of a
precipitate; if we digest bones with strong hot muriatic acid so as to
accelerate their decomposition, a portion of the cartilage dissolves in
the acid with a manifest disengagement of carbonic acid gas, which
breaks the interior mass, and causes the half-softened bone to begin to
split into fibrous plates, separable in the direction of their length.
According to Marx these plates, when sufficiently thin, possess, like
scales of mica, the property of polarising light, a phenomenon which
becomes more beautiful still when we soak them with the essential oil of
the bark of the Laurus Cassia. The osseous cartilage is formed before
the earthy part. The long bones are then solid, and they become hollow
only in proportion as the earthy salts appear. In the new-born infant, a
large portion of the bones is but partially filled with these salts,
their deposition in cartilage takes place under certain invariable
_points of ossification_, and begins at a certain period after
conception, so that we may calculate the age of the foetus according to
the progress which ossification has made.

The earthy parts of bones are composed principally of the phosphate and
carbonate of lime in various proportions, variable in different animals,
and mixed with small quantities, equally variable, of phosphate of
magnesia and fluate of lime. The easiest means of procuring the earthy
salts of bones consists in burning them to whiteness, but the earthy
residuum procured in this manner, contains substances which did not
exist beforehand in the bones, and which did not form a part of their
earthy salts; as for example sulphate of soda, produced at the expense
of the sulphur of the bones and the alkaline carbonate, proceeding from
the cartilage with which it was combined. On the other hand, the greater
part of the lime has lost its carbonic acid. As the sulphuric acid is
the product of combustion, it is obvious that an acidulous solution of a
fresh bone can afford no precipitate with muriate of barytes. The
phosphate of lime contained in the bone-salts is a subphosphate,
consisting, according to Berzelius, of three prime equivalents of the
acid, and 8 of the base; or of 2,677 parts of the former, and 2,848 of
the latter. It is always obtained when we precipitate the phosphate of
lime by an excess of ammonia. When calcined bones are distilled in a
retort with their own weight of sulphuric acid, a little fluoric acid is
disengaged, and it acts on the surface of the glass. The following
analyses of the bones of men and horned cattle, are given by Berzelius.
They were dried after being stripped of their fat and periosteum till
they lost no more weight.

  +-----------------------------------------+-----------+--------+
  |                                         |Human bone.|Ox bone.|
  +-----------------------------------------+-----------+--------+
  |Cartilage completely soluble in water    |  32·17 }  |  33·3  |
  |Vessels                                  |   1·13 }  |        |
  |Subphosphate with a little fluate of lime|  53·04    |  57·35 |
  |Carbonate of lime                        |  11·3     |   3·85 |
  |Phosphate of magnesia                    |   1·16    |   2·05 |
  |Soda with very little muriate of soda    |   1·20    |   3·45 |
  |                                         | ------    | ------ |
  |                                         | 100·00    | 100·00 |
  +-----------------------------------------+-----------+--------+

The most essential difference in the composition of these bones is that
those of man contain three times as much carbonate of lime as those of
the ox; and that the latter are richer in phosphate of lime and magnesia
in the same proportion. Fernandez de Barros has established a comparison
between the phosphate and carbonate of lime in the bones of different
animals. He found in 100 parts of earthy salt of the bones of the
following animals:--

  +-----+------------------+-----------+
  |     |Phosphate of lime.|Carb. lime.|
  +-----+------------------+-----------+
  |Lion |       95·0       |    2·5    |
  |Sheep|       80·0       |   19·3    |
  |Hen  |       88·9       |   10·4    |
  |Frog |       95·2       |    2·4    |
  |Fish |       91·9       |    5·3    |
  +-----+------------------+-----------+

The bones of fish are divided into those which contain earthy salts and
those which have none, called cartilaginous fishes. The enamel of the
teeth is composed as follows:--

  +-------------------------------------+-------------+----------+
  |                                     |Human enamel.|Ox enamel.|
  +-------------------------------------+-------------+----------+
  |Phosphate of lime with fluate of lime|    88·5     |   85·0   |
  |Carbonate of lime                    |     8·0     |    7·1   |
  |Phosphate of magnesia                |     1·5     |    3·0   |
  |Soda                                 |     0·0     |    1·4   |
  |Brown membranes attached to the tooth|     2·0     |    3·5   |
  |alkali, water                        |             |          |
  |                                     |   -----     |  -----   |
  |                                     |   100·0     |  100·0   |
  +-------------------------------------+-------------+----------+

In the arts, the bones are employed by turners, cutlers, manufacturers
of animal charcoal; and, when calcined, by assayers for making cupels.
In agriculture, they are employed as a manure, for which purpose they
should be ground in a mill, and the powder sowed along with the seeds in
a drill. It is supposed, in many cases, to increase the crop in weight
of grain and straw together, by from 40 to 50 per cent. In France, soup
is extensively made by dissolving bones in a steam-heat of two or three
days’ continuance. The shavings of hartshorn, which is a species of
bone, afford an elegant jelly: the shavings of calves’ bones may be used
in their stead.

Living bones acquire a red tinge when the animals receive madder with
their food; but they lose it when the madder is discontinued for some
time.


BONE BLACK (_Noir d’os_, Fr.; _Knochenschwartz_, Germ.), or _Animal
charcoal_, as it is less correctly called, is the black carbonaceous
substance into which bones are converted by calcination in close
vessels. This kind of charcoal has two principal applications; to
deprive various solutions, particularly syrups, of their colouring
matters, and to furnish a black pigment. The latter subject will be
treated of under IVORY BLACK.

The discovery of the antiputrescent and decolouring properties of
charcoal in general, is due to Lowitz, of Petersburg; but their
modifications have occupied the attention of many chemists since his
time. Kels published, in 1798, some essays on the discolouring of
indigo, saffron, madder, syrup, &c. by means of charcoal, but he
committed a mistake in supposing bone black to have less power than the
charcoal of wood. The first useful application of charcoal to the
purification of raw colonial sugar was made by M. Guillon, who brought
into the French markets considerable quantities of fine syrups, which he
discoloured by ground wood charcoal, and sold them to great advantage,
as much superior to the cassonades of that time. In 1811, M. Figuier, an
apothecary at Montpellier, published a note about animal charcoal,
showing that it blanched vinegars and wines with much more energy than
vegetable charcoal; and, lastly, in 1812, M. Derosnes proposed to
employ animal charcoal in the purification of syrups and sugar refining.
The quantities of bone black left in the retorts employed by MM. Payen,
for producing crude carbonate of ammonia, furnished abundant materials
for making the most satisfactory experiments, and enabled these
gentlemen soon to obtain ten per cent. more of refined sugar from the
raw article than had been formerly extracted, and to improve, at the
same time, the characters of the lumps, bastards, treacle, &c.

[Illustration: 135 136 137 138]

The calcination of bones is effected by two different systems of
apparatus; by heating them in a retort similar to that in which coal is
decomposed in the gas works, or in small pots piled up in a kiln. For
the description of the former, see GAS-LIGHT. On the second plan, the
bones, broken into pieces, are put into small cast-iron pots of the form
shown in _fig._ 135., about three eighths of an inch thick, two of which
are dexterously placed with their mouths in contact, and then luted
together with loam. The lip of the upper pot is made to slip inside of
the under one. These double vessels, containing together about fifty
pounds of bones, are arranged alongside, and over each other, in an
oven, like a potter’s kiln, till it be filled. The oven or kiln may be
either oblong or upright. The latter is represented in _fig._ 136, 137,
138. A is the fireplace or grate for the fuel; C C are the openings in
the dome of the furnace through which the flame flows; the divisions of
these orifices are shown in _fig._ 138. B is the wall of brick-work. D
the space in which the pots are distributed. E is the door by which the
workman carries in the pots, which is afterwards built up with fire
bricks, and plastered over with loam. This door is seen in _fig._ 136. F
F are the lateral flues for conveying the disengaged gases into the air.

[Illustration: 139 140]

_Fig._ 139. is a longitudinal section, and _fig._ 140. a ground plan of
a horizontal kiln for calcining bones. _a_ is the fire-chamber, lying
upon a level with the sole of the kiln; it is separated by a pillar _b_,
from the calcining hearth _c_. In the pillar or wall, several rows of
holes _d_, are left at different heights; _e_ is the entrance door; _f_,
the outlet vents for the gases, vapours, and smoke, into the chimney
_g_; _h_, a sliding damper-plate for regulating the admission of the air
into the fire in the space _a_.

By this arrangement the offensive emanations are partly consumed, and
partly carried off with the smoke. To destroy the smell completely, the
smoke should be made to pass through a second small furnace.

The number of pots that may be put into a kiln of this kind depends, of
course, upon its dimensions; but, in general, from 100 to 150 are piled
up over each other, in columns, at once; the greatest heat being nearest
the roof of the kiln; which resembles, in many respects, that used for
baking pottery ware.

In both kilns the interior walls are built of fire-bricks. In the oblong
one, the fiercest heat is near the vaulted roof; in the upright one,
near the sole; and the pots, containing the larger lumps of bones,
should be placed accordingly near the top of the former, and the bottom
of the latter. Such a kiln may receive about seventy double pots,
containing in the whole thirty-five cwt. of bones.

After the earth is filled with the pots, and the entrance door is shut,
the fire is applied at first moderately, but afterwards it must be
raised and maintained, at a brisk heat, for eight or ten hours. The door
of the ash-pit and the damper may now be nearly closed, to moderate the
draught, and to keep up a steady ignition for six or eight hours longer,
without additional firing; after which the doors must be all opened to
cool the furnace. When this is done, the brick-work of the entrance door
must be taken down, the kiln must be emptied, and immediately filled
again with a set of pots previously filled with bones, and luted
together: the pots which have been ignited may, in the course of a short
time, be opened, and the contents put into the magazine. But in
operating with the large decomposing cylinder retort, the bones being
raked out hot, must be instantly tossed into a receiver, which can be
covered-in air-tight till they are cool.

The bones lose upon the average about one half of their weight in the
calcination. In reference to the quality of the black, experience has
shown that it is so much more powerful as a discolouring agent, as the
bones from which it was made have been freer from adhering fatty,
fleshy, and tendinous matters.

The charcoal is ground in a mill, either to a fine powder and sifted; or
into a coarse granular state, like gunpowder, for the preparation of
which two sieves are required, one with moderately fine meshes, to allow
the small dust to pass through, and one with large meshes, to separate
the proper sized grains from the coarser lumps. Either a corn-mill, an
edgestone mill, or a steel cylinder mill, may be employed for grinding
bone-black, and it is generally damped in the operation to keep down the
fine dust.

Bone-black, as found in commerce, is very variable in its discolouring
power, which arises from its having been exposed either to too great a
heat which has glazed its carbon, or to too low a heat which has left
its albumen imperfectly decomposed. A steady ignition of due continuance
is the proper decomposing temperature. Its composition is generally as
follows:--

Phosphate of lime, with carbonate of lime, and a little sulphuret of
iron, or oxide of iron, 88 parts; iron in the state of a silicated
carburet, 2 parts; charcoal containing about one fifteenth of azote, 10
parts. None of the substances present, except the charcoal, possesses
separately any discolouring power.

The quality may be tested by a solution of brown sugar, or molasses, or
of indigo in sulphuric acid. The last is generally preferred by the
French chemists, who have occupied themselves most with this subject,
and it contains usually one thousandth part of its weight of this
dye-drug of the best quality. Other animal substances yield a charcoal,
possessed of very considerable discolouring properties. The following
table by M. Bussy exhibits an interesting comparison of almost every
kind of charcoal in this point of view.

Table of the discolouring powers of different charcoals.

  +--------------------------+-------+-------+--------+--------+------+
  |                          |       |Indigo |Molasses|Blanch- |Power |
  |Species of Charcoal.      |Weight.| test  |  test  |ing by  | by   |
                             |       | con-  |  con-  |indigo. |molas-|
  |                          |       |sumed. | sumed. |        |ses.  |
  +--------------------------+-------+-------+--------+--------+------+
  |                          |Gramme.|Litres.|        |        |      |
  |Blood calcined with potash|   1   | 1·60  |  0·18  | 50     | 20   |
  |Ditto with chalk          |   1   | 0·57  |  0·10  | 18     | 11   |
  |Ditto with phosp. lime    |   1   | 0·38  |  0·09  | 12     | 10   |
  |Gelatine ditto with potash|   1   | 1·15  |  0·14  | 36     | 15·5 |
  |Albumen ditto ditto       |   1   | 1·08  |  0·14  | 34     | 15·5 |
  |Starch ditto ditto        |   1   | 0·34  |  0·08  | 10·6   |  8·8 |
  |Charcoal from acet. potash|   1   | 0·18  |  0·04  |  5·6   |  4·4 |
  |Ditto from carb. soda by  |   1   | 0·38  |  0·08  | 12     |  8·8 |
  |phosphorus                |       |       |        |        |      |
  |Calcined lamp black       |   1   | 0·128 |  0·03  |  4     |  3·3 |
  |Ditto ditto potash        |   1   | 0·55  |  0·09  | 15·2   | 10·6 |
  |Bone black treated with   |   1   | 1·45  |  0·18  | 45     | 20   |
  |mur. acid and potash      |       |       |        |        |      |
  |Bone black ditto with mur.|   1   | 0·06  |  0·015 |  1·87  |  1·6 |
  |acid                      |       |       |        |        |      |
  |Oil calcined with phosp.  |   1   | 0·064 |  0·017 |  2     |  1·9 |
  |of lime                   |       |       |        |        |      |
  |Crude bone black          |   1   | 0·032 |  0·009 |  1     |  1   |
  +--------------------------+-------+-------+--------+--------+------+

With regard to the mode of operation of bone black on coloured liquids,
M. Payen showed in his prize essay, 1. That the decolouring power of
charcoal depends in general upon its state of division; 2. That in the
various charcoals, the carbonaceous matter acts only upon the colouring
matters, combining with and precipitating them; 3. That in the
application of charcoal to the refining of sugar, it acts also upon the
gluten, for it singularly promotes crystallisation; 4. That according to
the above principles, the decolouring action of charcoals may be so
modified, as to make the most inert become the most active; 5. That the
distinction between animal and vegetable charcoals is improper, and that
we may substitute for it that of dull and brilliant charcoals; 6. That
of the substances present in charcoal besides carbon, and particularly
animal charcoal, those which favour the decolouring action, have an
influence relative only to the carbon; they serve as auxiliaries to it,
by insulating its particles, and presenting them more freely to the
action of the colouring matter; 7. That animal charcoal, besides its
decolouring power, has the valuable property of taking lime in solution
from water and syrup; 8. That neither vegetable, nor other charcoals,
besides the animal, have this power of abstracting lime; 9. That by the
aid of the decolorimeter, or graduated tube charged with test solution
of indigo or molasses, it is easy to appreciate exactly the decolouring
properties of all kinds of charcoal.

Different varieties of lignite (fossilized wood) or even pit coal, when
well carbonized in close vessels, afford a decolouring charcoal of
considerable value. By reducing 100 parts of clay into a thin paste with
water, kneading into it 20 parts of tar, and 500 of finely ground pit
coal, drying the mixed mass, and calcining it out of contact of air, a
charcoally matter may be obtained not much inferior to bone-black in
whitening syrups.

The restoration of animal charcoal from burnt bones, for the purpose of
sugar refining, has been long practised in France. Mr. W. Parker has
lately made the following process the subject of a patent. The charcoal,
when taken from the vessels in which it has been employed for the
purposes of clarifying the sugar, is to be thoroughly washed with the
purest water that can be obtained, in order to remove all the saccharine
matter adhering to it. When the washing process has been completed, the
charcoal is laid out to dry, either in the open air or in a suitable
stove, and when perfectly free from moisture, it is to be separated into
small pieces and sifted through a sieve, the wires or meshes of which
are placed at distances of about two and a half in every inch. This
sifting will not only divide the charcoal into small pieces, but will
cause any bits of wood or other improper matters to be separated from
it.

The charcoal, thus prepared, is then to be packed lightly in cylindrical
vessels called crucibles, with some small quantity of bones, oil, or
other animal matter mixed with it. The crucibles are then to be closed
by covers, and luted at the joints, leaving no other opening but one
small hole in the centre of the cover, through which any gas, generated
within the vessel when placed in the oven or furnace, may be allowed to
escape.

The crucibles are now to be ranged round the oven, and placed, one upon
another, in vertical positions; and when the oven is properly heated,
gas will be generated within each crucible, and issue out from the
central hole. The gas thus emitted, being of an inflammable quality,
will take fire, and assist in heating the crucibles; and the operation
being carried on until the crucibles become of a red heat, the oven is
then to be closed, and allowed to cool; after which the crucibles are to
be removed, when the charcoal will be found to have become perfectly
renovated, and fit for use as before.


BORAX. A native saline compound of boracic acid and soda, found
abundantly in Thibet and in South America. The crude product from the
former locality was imported into Europe under the name of _tincal_, and
was purified from some adhering fatty matter by a process kept a long
time secret by the Venetians and the Dutch, and which consisted chiefly
in boiling the substance in water with a little quicklime.

Gmelin found borax, in prismatic crystals, to contain 46·6 per cent. of
water; and Arvredson, in the calcined state, to consist of 68·9 of acid
and 31·1 soda, in 100 parts. M. Payen describes an octahedral borax,
which contains only 30·64 per cent. of water, and is therefore preferred
by the braziers in their soldering processes.

Borax has a sweetish, somewhat lixivial taste, and affects vegetable
colours like an alkali; it is soluble in 12 parts of cold and 2 of
boiling water. It effloresces and becomes opaque in a dry atmosphere,
and appears luminous, by friction, in the dark. It melts at a heat a
little above that of boiling water, and gives out its water of
crystallization, after which it forms a spongy mass, called calcined
borax. The octahedral borax, which is prepared by crystallization, in a
solution of 1·256 sp. gr., kept up at 145° F., is not efflorescent. When
borax is ignited, it fuses into a glassy-looking substance.

The following is the improved mode of purifying borax. The crude
crystals are to be broken into small lumps, and spread upon a filter
lined with a lead grating, under which a piece of cloth is stretched
upon a wooden frame. The lumps are piled up to the height of 12 inches,
and washed with small quantities of a caustic soda lye of 5° B. (sp. gr.
1·033) until the liquor comes off nearly colourless; they are then
drained, and put into a large copper of boiling water, in such
quantities that the resulting solution stands 20° B. (sp. gr. 1·160).
Carbonate of soda, equivalent to 12 per cent. of the borax must now be
added; the mixed solution is allowed to settle, and the clear liquid
syphoned off into crystallizing vessels. Whenever the mother waters get
foul, they must be evaporated to dryness in cast-iron pots, and roasted,
to burn away the viscid colouring matter.

Borax is sometimes adulterated with alum and common salt: the former
addition may be readily detected by a few drops of water of ammonia,
which will throw down its alumina; and the latter by nitrate of silver,
which will give with it a precipitate insoluble in nitric acid.

The native boracic acid obtained from the lakes of Tuscany, which has
been manufactured in France into borax, has greatly lowered the price of
this article of commerce. When MM. Payen and Cartier first began the
business, they sold the crystals at the same price as the Dutch, viz. 7
francs the kilogramme (2-1/5 lbs. avoird.); but, in a few years, they
could obtain only 2 francs and 60 centimes, in consequence of the market
getting overstocked. The annual consumption of France in 1823 was 25,000
kilos., and the quantity produced in M. Payen’s works was 50,000. The
mode of making borax from the acid is as follows:--The lake water is
evaporated in graduation houses, and then concentrated in boilers till
it crystallizes. In that state it is carried to Marseilles. About 500
kilogrammes of water are made to boil in a copper, and 600 kilogrammes
of crystallized carbonate of soda are dissolved in it by successive
additions of 20 kilogrammes. The solution being maintained at nearly the
boiling point, 500 kilogrammes of the crystallized boracic acid of
Tuscany are introduced, in successive portions. At each addition of
about 10 kilogrammes, a lively effervescence ensues, on which account
the copper should be of much greater capacity than is sufficient to
contain the liquors. When the whole acid has been added, the fire must
be damped by being covered up with moist ashes, and the copper must be
covered with a tight lid and blankets, to preserve the temperature
uniform. The whole is left in this state during 30 hours; the clear
liquor is then drawn off into shallow crystallizing vessels of lead, in
which it should stand no higher than 10 or 12 inches, to favour its
rapid cooling. At the end of three days in winter, and four in summer,
the crystallization is usually finished. The mother water is drawn off,
and employed, instead of simple water, for the purpose of dissolving
fresh crystals of soda. The above crystals are carefully detached with
chisels, redissolved in boiling water, adding for each 100 kilos., 10
kilos. of carbonate of soda. This solution marks 20° B. (sp. gr. 1·160);
and, at least, one ton (1000 kilos.) of borax should be dissolved at
once, in order to obtain crystals of a marketable size. Whenever this
solution has become boiling hot, it must be run off into large
crystallizing lead chests of the form of inverted truncated pyramids,
furnished with lids, enclosed in wooden frames, and surrounded with mats
to confine the heat. For a continuous business there should be at least
18 vessels of this kind; as the solution takes a long time to complete
its crystallization, by cooling to 30° C. (86° F.). The borax crystals
are taken out with chisels, after the liquor has been drawn off, and the
whole has become cold.

One hundred parts of the purest acid, usually extracted from the lakes
of Tuscany, contain only fifty parts of the real boracic acid, and yield
no more, at the utmost, than 140 or 150 of good borax.

Dry borax acts on the metallic oxides at a high temperature, in a very
remarkable manner, melting and vitrifying them into beautiful coloured
glasses. On this account it is a most useful reagent for the blowpipe.
Oxide of chrome tinges it of an emerald green; oxide of cobalt, an
intense blue; oxide of copper, a pale green; oxide of tin, opal; oxide
of iron, bottle green and yellow; oxide of manganese, violet; oxide of
nickel, pale emerald green. The white oxides impart no colour to it by
themselves. In the fusion of metals borax protects their surface from
oxidizement, and even dissolves away any oxides formed upon them; by
which twofold agency it becomes an excellent flux, invaluable to the
goldsmith in soldering the precious metals, and to the brazier in
soldering copper and iron.

Borax absorbs muriatic and sulphurous acid gases, but no others, whereby
it becomes, in this respect, a useful means of analysis.

The strength or purity of borax may be tested by the quantity of
sulphuric acid requisite to neutralize a given weight of it, as
indicated by tincture of litmus.

When mixed with shell-lac in the proportion of one part to five, borax
renders that resinous body soluble in water, and forms with it a species
of varnish.

Boracic acid is a compound of 31·19 of boron and 68·81 oxygen, in 100
parts. Its prime equivalent referred to oxygen 100, is 871·96.

The following process for refining the native Indian borax or tincal,
has been published by MM. Robiquet and Marchand:--

It is put into large tubs, covered with water for 3 or 4 inches above
its surface, and stirred through it several times during six hours. For
400 pounds of the tincal there must now be added one pound of quicklime
diffused through two quarts of water. Next day the whole is thrown upon
a sieve, to drain off the water with the impurities, consisting, in some
measure, of the fatty matter combined with the lime, as an insoluble
soap. The borax, so far purified, is to be dissolved in 2-1/2 times its
weight of boiling water, and eight pounds of muriate of lime are to be
added for the above quantity of borax. The liquor is now filtered,
evaporated to the density of 18° or 20° B. (1·14 to 1·16 sp. grav.), and
set to crystallize in vessels shaped like inverted pyramids, and lined
with lead. At the end of a few days, the crystallization being
completed, the mother waters are drawn off, the crystals are detached
and dried. The loss of weight in this operation is about 20 per cent.

The quantity of borax imported into the United Kingdom in 1835 was
335,224 pounds; whereof 122,022 pounds were exported. The duty is 10_s._
upon the refined, and 4_s._ unrefined.


BOOKBINDING, is the art of sewing together the sheets of a book; and
securing them with a back and side boards. Binding is distinguished from
stitching, which is merely sewing the leaves without bands or backs; and
from half-binding, which consists in securing the back only with
leather, the pasteboard sides being covered with blue or marble paper;
whereas in binding, both the back and sides are covered with leather.

Bookbinding, according to the present mode, is performed in the
following manner:--The sheets are first folded into a certain number of
leaves, according to the form in which the book is to appear; viz. two
leaves for folios, four for quartos, eight for octavos, twelve for
duodecimos, &c. This is done with a slip of ivory or boxwood, called a
folding stick; and in the arrangement of the sheets the workmen are
directed by the catch-words and signatures at the bottom of the pages.
When the leaves are thus folded and arranged in proper order, they are
usually beaten upon a stone with a heavy hammer, to make them solid and
smooth, and are then condensed in a press. After this preparation they
are sewed in a sewing press, upon cords or packthreads called bands,
which are kept at a proper distance from each other, by drawing a thread
through the middle of each sheet, and turning it round each band,
beginning with the first and proceeding to the last. The number of bands
is generally six for folios, and five for quartos, or any smaller size.
The backs are now glued, and the ends of the bands are opened, and
scraped with a knife, that they may be more conveniently fixed to the
pasteboard sides; after which the back is turned with a hammer, the book
being fixed in a press between boards, called backing boards, in order
to make a groove for admitting the pasteboard sides. When these sides
are applied, holes are made in them for drawing the bands through, the
superfluous ends are cut off, and the parts are hammered smooth. The
book is next pressed for cutting; which is done by a particular machine
called the plough, to which is attached a knife. See the figures and
descriptions _infra_. It is then put into a press called the cutting
press, betwixt two boards, one of which lies even with the press, for
the knife to run upon; and the other above for the knife to cut against.
After this the pasteboards are cut square with a pair of iron shears;
and last of all, the colours are sprinkled on the edges of the leaves,
with a brush made of hog’s bristles; the brush being held in the one
hand, and the hair moved with the other.

Different kinds of binding are distinguished by different names, such as
law binding, marble binding, French binding, Dutch binding, &c. In Dutch
binding, the backs are vellum. In French binding a slip of parchment is
applied over the back between each band, and the ends are pasted upon
the inside of each pasteboard. This indorsing, as it is called, is
peculiar to the French binders; who are enjoined, by special
_ordonnance_, to back their books with parchment. The parchment is
applied in the press, after the back has been grated to make the paste
take hold. The Italians still bind in a coarse thick paper, and this
they call binding _alla rustica_. It is extremely inconvenient, as it is
liable to wear without particular care.

A patent was obtained in 1799 by Messrs. John and Joseph Williams,
stationers in London, for an improved method of binding books of every
description. The improvement consists of a back, in any curved form,
turned a little at the edges, and made of iron, steel, copper, brass,
tin, or of ivory, bone, wood, vellum, or, in short, any material of
sufficient firmness. This back is put on the book before it is bound, so
as just to cover without pressing the edges; and the advantage of it is
that it prevents the book, when opened, from spreading on either side,
and causes it to rise in any part to nearly a level surface. In this
method of binding the sheets are prepared in the usual manner, then
sewed on vellum slips, glued, cut, clothed, and boarded, or half
boarded; the firm back is then fastened to the sides by vellum drawn
through holes, or secured by inclosing it in vellum or ferret wrappers,
or other materials pasted down upon the boards, or drawn through them.

A patent was likewise obtained in 1800 by Mr. Ebenezer Palmer, a London
stationer, for an improved way of binding books, particularly merchants’
account-books. This improvement has been described as follows:--let
several small bars of metal be provided about the thickness of a
shilling or more, according to the size and thickness of the book; the
length of each bar being from half an inch to several inches, in
proportion to the strength required in the back of the book. At each end
of every bar let a pivot be made of different lengths, to correspond to
the thickness of two links which they are to receive. Each link must be
made in an oval form, and contain two holes proportioned to the size of
the pivots, these links to be the same metal as the hinge, and each of
them nearly equal in length to the width of two bars. The links are then
to be riveted on the pivots, each pivot receiving two of them, and thus
holding the hinge together, on the principle of a link-chain or hinge.
There must be two holes or more of different sizes, as may be required,
on each bar of the hinge or chain; by means of these holes each section
of the book is strongly fastened to the hinge which operates with the
back of the book, when bound, in such a manner as to make the different
sections parallel with each other, and thus admit writing without
inconvenience on the ruled lines, close to the back.

The leather used in covering books is prepared and applied as follows:
being first moistened in water, it is cut to the size of the book, and
the thickness of the edge is paired off on a marble stone. It is next
smeared over with paste made of wheat flour, stretched over the
pasteboard on the outside, and doubled over the edges within. The book
is then corded, that is, bound firmly betwixt two boards, to make the
cover stick strongly to the pasteboard and the back; on the exact
performance of which the neatness of the book in a great measure
depends. The back is then warmed at the fire to soften the glue, and the
leather is rubbed down with a bodkin or folding stick, to set and fix it
close to the back of the book. It is now set to dry, and when dry the
boards are removed; the book is then washed or sprinkled over with a
little paste and water, the edges and squares blacked with ink, and then
sprinkled fine with a brush, by striking it against the hand or a stick;
or with large spots, by being mixed with solution of green vitriol,
which is called marbling. Two blank leaves are then pasted down to the
cover, and the leaves, when dry, are burnished in the press, and the
cover rolled on the edges. The cover is now glazed twice with the white
of an egg, filleted, and last of all, polished, by passing a hot iron
over the glazed colour.

The employment in book binding of a rolling press for smoothing and
condensing the leaves, instead of the hammering which books have usually
received, is an improvement introduced several years ago into the trade
by Mr. W. Burn. His press consists of two iron cylinders about a foot in
diameter, adjustable in the usual way, by means of a screw, and put in
motion by the power of one man or of two, if need be, applied to one or
two winch-handles. In front of the press sits a boy who gathers the
sheets into packets, by placing two, three, or four upon a piece of tin
plate of the same size, and covering them with another piece of tin
plate, and thus proceeding by alternating tin plates and bundles of
sheets till a sufficient quantity have been put together, which will
depend on the stiffness and thickness of the paper. The packet is then
passed between the rollers and received by the man who turns the winch,
and who has time to lay the sheets on one side, and to hand over the tin
plates by the time that the boy has prepared a second packet. A minion
bible may be passed through the press in one minute, whereas the time
necessary to beat it would be twenty minutes. It is not, however, merely
a saving of time that is gained by the use of the rolling press; the
paper is made smoother than it would have been by beating, and the
compression is so much greater, that a rolled book will be reduced to
about five-sixths of the thickness of the same book if beaten. A shelf,
therefore, that will hold fifty books bound in the usual way would hold
nearly sixty of those bound in this manner, a circumstance of no small
importance, when it is considered how large a space even a moderate
library occupies, and that book-cases are an expensive article of
furniture. The rolling press is now substituted for the hammer by
several considerable bookbinders.

[Illustration: 141 142]

_Fig._ 141. represents the sewing press, as it stands upon the table,
before which the bookbinder sits. _Fig._ 142. is a ground plan without
the parts _a_ and _n_ in the former figure. A is the base-board,
supported upon the cross bars _m n_, marked with dotted lines in _fig._
142. Upon the screw rods _r r_ _fig._ 141. the nuts _t d_ serve to fix
the flat upper bar _n_, at any desired distance from the base. That bar
has a slit along its middle, through which the hooks below _z z_ pass
down for receiving the ends of the sewing cords _p p_, fixed at _y y_,
and stretched by the thumb-screws _z z_. The bar _y y_ is let into an
oblong space cut out of the front edge of the base board and fixed there
by a movable pin _a_, and a fixed pin at its other end round which it
turns.

[Illustration: 143]

_Fig._ 143. is the bookbinder’s cutting press, which is set upright upon
a sort of chest for the reception of the paper parings; and consists of
three sides, being open above and to the left hand of the workman. The
pressbar, or beam _a_, has two holes _n n_ upon its under surface, for
securing it to two pegs standing on the top of the chest. The screw rods
_t t_ pass through two tapped holes in the bar, marked with _b c_ at its
upper end; their heads _r r_ being held by the shoulders _o o_. The
heads are pierced with holes into which lever pins are thrust for
screwing the rods hard up. The heavy beam _a_ remains immovable, while
the parallel bar with the book is brought home towards it by the two
screws. The two rulers _s s_ serve as guides to preserve the motions
truly parallel; and the two parallel lath bars _b c_ guide between them
the end bar _e_, of the plough, whose knife is shown at _i_, with its
clamping screw _z_.

[Illustration: 144 145]

Mr. Oldham, printing engineer of the Bank of England, distinguished for
mechanical ingenuity, has contrived a convenient machine for cutting the
edges of books, banknotes, &c. either truly square or polygonal, with
mathematical precision. _Fig._ 144. represents an end elevation of the
machine. _Fig._ 145. a side view of the same, the letters of reference
indicating the same parts of the machine in each of the figures.

[Illustration: 146 147]

_a_, is the top cross bar with rectangular grooves _b b_; _c c_, are
side posts; _d d_, cross feet to the same, with strengthening brackets;
_e e_, a square box, in which the press stands, for holding waste
cuttings. _Fig._ 146. is a cross section of the upright posts, _c c_,
taken horizontally. There are rectangular grooves in the upright posts,
for the projecting ends of the cast iron cross bracket _f_, to slide up
and down in. In the middle of the under-side of this piece _f_, there is
a boss, within which is a round recess, to receive the top of the screw
_g_, which works in the cast iron cross piece _h_, similarly made with
the former, but bolted firmly to the posts _c c_. Upon the screw _g_
there is a circular handle or ring _i_, for partially turning the screw,
and immediately over it cross holes for tightening the press by means of
a lever bar. Upon the cross piece _f_, is bolted the board _j_, and upon
each end of this board is made fast the rabbetted pieces _k k_, for
another board _l_, to slide in. Across the middle of this board, and
parallel to the pieces _k k_, the tongue piece _m_, is made fast, which
fits into a groove in the bottom of board _l_. A horizontal
representation of this is seen at _fig._ 147. and immediately under this
view is also seen an end view of _l_, and _f_, connected together, and a
side view of _f_ by itself. In the middle of the board _l_, is a pin
for a circular board _n_, to turn upon, and upon this latter board is
placed the “material to be cut,” with a saving piece between it, and the
circular piece which is to be divided upon its edge into any number of
parts required, with a stationary index on the board _l_, to point to
each.

It will now be understood that the “material to be cut,” may be turned
round upon the centre pin of the board _n_, and also that both it and
the board can be shifted backward and forward under the top cross piece
_a_, and between the side slide slips _k k_, the surfaces of which
should also be divided into inches and tenths.

The plough, _fig._ 148., shown in several positions, is made to receive
two knives or cutters as the “material to be cut” may require, and which
are situated in the plough as I now describe. The plough is composed of
three principal parts, namely, the top, and its two sides. The top _o_,
is made the breadth of the cross piece _a_, and with a handle made fast
thereon. The sides _p p_, are bolted thereto, with bolts and nuts
through corresponding holes in the top and sides. The figures below give
inside views, and cross sections of the details of the manner in which
the cutters and adjustments are mounted. A groove is cut down each cheek
or side, in which are placed screws that are held at top and bottom from
moving up and down, but by turning they cause the nuts upon them to do
so; they are shown at _q q_. These nuts have each a pin projecting
inwards, that go into plain holes made in the top ends of cutters _r r_.
The 148th. and following figs. are 1/4 in scale.

[Illustration: 148 149 150 151 152 153 154]

The cutters, and the work for causing them to go up and down, are sunk
into the cheeks, so as to be quite level with their inner surfaces.
_Fig._ 149. shows one of those screws apart, how fixed, and with
moveable nut and projecting pin. The top of each screw terminates with a
round split down, and above it a pinion wheel and boss thereon, also
similarly split. This pinion fits upon the split pin. Above, there is
cross section of a hollow coupling cap with steel tongue across, that
fits into both the cuts of the screw pin and pinion boss, so that when
lowered upon each other, they must all turn together. In the middle and
on the top of the upper piece _o_, the larger wheel _s_, runs loose upon
its centre, and works into the two pinion-wheels _t t_. The wheel _s_
has a fly-nut with wings mounted upon it.

It will now be seen, when the plough is in its place as at _fig._ 150.,
that if it be pushed to and fro by the right hand, and the nut
occasionally turned by the left, the knives or cutters will be protruded
downwards at the same time, and these either will or will not advance as
the coupling caps _u u_ are on or off. The ribs _v v_, run in the
grooves _b b_, _fig._ 144., and keep the cutters to their duty, working
steadily. The top cross bar _a_, is the exact breadth of a bank-note, by
which means both knives are made to cut at the same time. The paper is
cut uniformly to one length, and accurately square.

By the use of this machine, the air-pump paper-wetting apparatus, and
appendant press, the paper of 45,000 notes is fully prepared in one hour
and a half by one person, and may then be printed. It is not so much
injured by this process as by the ordinary method of clipping by hand,
soaking it, &c., which more or less opens and weakens the fabric,
especially of bank-note paper.

One of the greatest improvements ever made in the art of bookbinding is,
apparently, that for which Mr. William Hancock has very recently
obtained a patent. After folding the sheets in double leaves, he places
them vertically, with the edges forming the back of the book downwards
in a concave mould, of such rounded or semi-cylindrical shape as the
back of the book is intended to have. The mould for this purpose
consists of two parallel upright boards, set apart upon a cradle frame,
each having a portion or portions cut out vertically, somewhat deeper
than the breadth of the book, but of a width nearly equal to its
thickness before it is pressed. One of these upright boards may be
slidden nearer to or farther from its fellow, by means of a guide bar,
attached to the sole of the cradle. Thus the distance between the
concave bed of the two vertical slots in which the book rests, may be
varied according to the length of the leaves. In all cases about
one-fourth of the length of the book at each end projects beyond the
board, so that one half rests between the two boards. Two or three
packthreads are now bound round the leaves thus arranged, from top to
bottom of the page in different lines, in order to preserve the form
given to the back of the mould in which it lay. The book is next
subjected to the action of the press. The back, which is left projecting
_very slightly_ in front, is then smeared carefully by the fingers with
a solution of caoutchouc, whereby each paper-edge receives a small
portion of the cement. In a few hours it is sufficiently dry to take
another coat of a somewhat stronger caoutchouc solution. In 48 hours, 4
applications of the caoutchouc may be made and dried. The back and the
adjoining part of the sides are next covered with the usual band or
fillet of cloth, glued on with caoutchouc; after which the book is ready
to have the boards attached, and to be covered with leather or parchment
as may be desired.

We thus see that Mr. Hancock dispenses entirely with the operations of
stitching, sewing, sawing-in, hammering the back, or the use of paste
and glue. Instead of leaves attached by thread stitches at 2 or 3
points, we have them agglutinated securely along their whole length.
Books bound in this way open so perfectly flat upon a table without
strain or resilience, that they are equally comfortable to the student,
the musician, and the merchant. The caoutchouc cement moreover being
repulsive to insects, and not affected by humidity, gives this mode of
binding a great superiority over the old method with paste or glue,
which attracted the ravages of the moth, and in damp situations allowed
the book to fall to pieces. For engravings, atlasses, and ledgers, this
binding is admirably adapted, because it allows the pages to be
displayed most freely, without the risk of dislocating the volume; but
for security, 3 or 4 stitches should be made. The leaves of music-books
bound with caoutchouc, when turned over, lie flat at their whole extent,
as if in loose sheets, and do not torment the musician like the leaves
of the ordinary books, which are so ready to spring back again.
Manuscripts and collections of letters which happen to have little or no
margin left at the back for stitching them by, may be bound by Mr.
Hancock’s plan without the least encroachment upon the writing. The
thickest ledgers thus bound, open as easily as paper in quire, and may
be written on up to the innermost margin of the book without the least
inconvenience.

Having inspected various specimens of Mr. Hancock’s workmanship, I
willingly bear testimony to the truth of the preceding statement. See
CLOTH BINDING.

[Illustration: 155]


BOTTLE MANUFACTURE. The following mechanism for moulding bottles, forms
the subject of a patent obtained by Henry Rickets of Bristol in 1822.
_Fig._ 155. is a section of the apparatus, consisting of a square frame,
_a a_, of iron or wood; this is fixed in a pit formed in the floor; _b
b_ is the base of the frame, with an aperture for knocking up the bottom
of the bottle; _c c_ are four legs secured to the frame-floor _b_, upon
which the mould is supported. The platform or stand of the mould _d d_
has an opening in its centre for the introduction of the bottom of the
mould, which is raised against the bottom of the bottle by the knocker
up; _e e_ are the sides of the mould; and _f f_ is the top of the mould
in two pieces, turning over upon the joints at _g g_, so as to form the
neck of the bottle; _h h_ are levers or arms for raising and depressing
the top pieces; _i i_ is a horizontal shaft or axle, turning in bearings
at each end, from which shaft two levers, _k k_, extend; these levers
are connected by upright rods, _l l_, to the levers or arms, _h h_, of
the top pieces _f f_.

The weight of the arms _h h_, and rods _l l_, will, by their gravity,
cause the top pieces to open, as shown by the dotted lines; in this
situation of the mould, the melted glass is to be introduced by a tube
as usual. The workman then steps with one foot upon the knob _m_, which
forces down the rod _n_, and by means of a short lever _o_, extending
from the shaft _i_, forces down the top pieces _f_, and closes the
mould, as seen in the figure; the glass is then made to extend itself to
the shape of the mould, by blowing as usual, so as to form the bottle,
and the workman at this time putting his other foot upon the knob _p_,
depresses the rod _q_, and hence raises the bottom of the mould by means
of the knocker-up, _r_, so as to form the bottom of the bottle.

At the bottom of the mould a ring is introduced of any required
thickness, for the purpose of regulating the capacity of the bottle;
upon which ring it is proposed to raise letters and figures, as a mould
to imprint the maker’s name and the size of the bottle. These moulds can
be removed and changed at pleasure. Under the knob _p_, a collar or
washer is to be introduced, of any required thickness, to regulate the
knocking up of the bottom, by which a perfect symmetry of form is
presented. In order to make bottles of different sizes or forms, the
mould is intended to be removed, and its place supplied by another mould
of different dimensions and figure; the lower parts of all the moulds
being made to fit the same frame. Such a mould ought to be prescribed by
legislative enactment, with an excise stamp to define the capacity of
every bottle, and thereby put an end to the interminable frauds
committed in the measure of wine and all other liquors sold by the
bottle.


BOUGIE. A smooth, flexible, elastic, slender cylinder, introduced into
the urethra, rectum, or œsophagus, for opening or dilating it, in cases
of stricture and other diseases. The invention of this instrument is
claimed by Aldereto, a Portuguese physician, but its form and uses were
first described by his pupil Amatus, in the year 1554. Some are solid,
and some hollow; some corrosive, and some mollifying. They generally owe
their elasticity to linseed oil, inspissated by long boiling, and
rendered drying by litharge. This viscid matter is spread upon a very
fine cord or tubular web of cotton, flax, or silk, which is rolled upon
a slab when it becomes nearly solid by drying, and is finally polished
in the same way.

Pickel, a French professor of medicine, published the following recipe
for the composition of bougies. Take 3 parts of boiled linseed oil, one
part of amber, and one of oil of turpentine; melt and mix these
ingredients well together, and spread the compound at three successive
intervals upon a silk cord or web. Place the pieces so coated in a stove
heated to 150° F.; leave them in it for 12 hours, adding 15 or 16 fresh
layers in succession, till the instruments have acquired the proper
size. Polish them first with pumice-stone, and finally smooth with
tripoli and oil. This process is the one still employed in Paris, with
some slight modifications; the chief of which is dissolving in the oil
one twentieth of its weight of caoutchouc to render the substance more
solid. For this purpose the caoutchouc must be cut into slender shreds,
and added gradually to the hot oil. The silk tissue must be fine and
open, to admit of the composition entering freely among its filaments.
Each successive layer ought to be dried first in a stove, and then in
the open air, before another is applied. This process takes two months
for its completion, in forming the best bougies called _elastic_; which
ought to bear twisting round the finger without cracking or scaling, and
extension without giving way, but retracting when let go. When the
bougies are to be hollow, a mandril of iron wire, properly bent with a
ring at one end, is introduced into the axis of the silk tissue. Some
bougies are made with a hollow axis of tin foil rolled into a slender
tube. Bougies are also made entirely of caoutchouc, by the intervention
of a solution of this substance in sulphuric ether, a menstruum
sufficiently cheap in France, on account of the low duty upon alcohol.
There are medicated bougies, the composition of which belongs to
surgical pharmacy. The manufacture of these instruments of various kinds
forms a separate and not inconsiderable branch of industry at Paris. MM.
Feburger and Lamotte are eminent in this line.


BRACES. (_Bretelles_, Fr. _Hosenträger_, Germ.) Narrow fillets or bands
of leather or textile fabric, which pass over the shoulders, and are
attached behind and before to the waistbands of pantaloons and trowsers,
in the act of wearing them, for supporting their weight, and _bracing_
them up to the body. It is a useful modern invention, superseding the
necessity of girding the belly with a tight girdle, as in former times.

[Illustration: 156 157]


BRAIDING MACHINE. (_Machine à lacets_, Fr.; _Bortenwerkerstuhl_, Germ.)
This being employed, not only to manufacture stay-laces, braid, and
upholsterer’s cord, but to cover the threads of caoutchouc for weaving
brace-bands, deserves a description in this work. Three threads at least
are required to make such a knitted lace, but 11, 13, or 17, and even 29
threads are often employed, the first three numbers being preferred.
They are made by means of a frame of a very ingenious construction,
which moves by a continuous rotation. We shall describe a frame with 13
threads, from which the structure of the others may be readily
conceived. The basis of the machine consists of four strong wooden
uprights, A, _fig._ 156, 157, 158., occupying the four angles of a
rectangle, of which one side is 14 inches long, the other 18 inches, and
the height of the rectangle about 40 inches. _Fig._ 156. is a section in
a horizontal plane, passing through the line _a b_ of _fig._ 157. which
is a vertical section in a plane passing through the centre of the
machine C, according to the line _c d_, _fig._ 156. The side X is
supposed to be the front of the frame; and the opposite side, Y, the
back. B, six spindles or skewers, numbered, from 1 to 6, placed in a
vertical position upon the circumference of a circle, whose centre
coincides with that of the machine at the point C. These six spindles
are composed, 1. Of so many iron shafts or axes D, supported in brass
collets E, (_fig._ 157.) and extended downwards within 6 inches of the
ground, where they rest in brass steps fixed upon a horizontal beam. 2.
Wooden heads, made of horn-beam or nut-tree, placed, the first upon the
upper end of each spindle, opposite the cut-out beam F, and the second
opposite the second beam G. 3. Wooden-toothed wheels, H, reciprocally
working together, placed between the beam G, and the collet-beam E. The
toothed wheels and the lower heads for each spindle are in one piece.

The heads and shafts of the spindles No. 1. and 6., are one fifth
stronger than those of the other spindles; their heads have five
semi-circular grooves, and wheels of 60 teeth, while the heads of the
others have only four grooves, and wheels of 48 teeth; so that the
number of the grooves in the six spindles is 26, one half of which is
occupied with the stems of the puppets I, which carry the 13 threads
from No. 1. to 13. The toothed wheels, which give all the spindles a
simultaneous movement, but in different directions, are so disposed as
to bring their grooves opposite to each other in the course of rotation.

K, the middle winglet, triple at bottom and quintuple at top, which
serves to guide the puppets in the direction they ought to pursue.

L, three winglets, single at top and bottom, placed exteriorly, which
serve a like purpose.

M, two winglets, triple at bottom and single at top, placed likewise
exteriorly, and which serve the same purposes as the preceding; _m_, are
iron pins inserted in the cut-out beam G, which serve as stops or limits
to the oscillations of the exterior winglets.

Now, if by any moving power (a man can drive a pair) rotation be
impressed upon the large spindle No. 1., in the direction of the arrow,
all the other spindles will necessarily pursue the rotatory movement
indicated by the respective arrows. In this case, the 13 puppets working
in the grooves of the heads of the spindles will be carried round
simultaneously, and will proceed each in its turn, from one extremity of
the machine to the opposite point, crossing those which have a
retrograde movement. The 13 threads united at the point N, situated
above the centre of the machine, will form at that point the braid,
which after having passed over the pulley _o_, comes between the two
rollers P Q, and is squeezed together, as in a flatting-mill, where the
braid is calendered at the same time that it is delivered. It is obvious
that the roller P, receives its motion from the toothed wheel of the
spindle No. 3., and from the intermediate wheels R, S, T, as well as
from the endless screw Z, which drives at proper speed the wheel W,
fixed upon the shaft of the roller P.

The braid is denser in proportion as the point N is less elevated above
the tops of the puppets; but in this case, the eccentric motion of these
puppets is much more sensible in reference to that point, towards which
all the threads converge, than when it is elevated. The threads which
must be always kept equally stretched by means of a weight, as we shall
presently see, are considerably strained by the traction, occasioned by
the constantly eccentric movement of the puppets. From this cause,
braiding machines must be worked at a moderate velocity. In general, for
fine work, 30 turns of the large spindle per minute are the utmost that
can safely be made.

[Illustration: 158]

The puppet or spindle of this machine, being the most important piece, I
have represented it in section, upon a scale one fourth of its actual
size, _fig._ 158. It is formed of a tube, _a_, of strong sheet iron well
brazed; _b_ is a disc, likewise of sheet iron, from which a narrow
fillet, _c_, rises vertically as high as the tube, where both are
pierced with holes, _d e_, through which the thread _f_ is passed, as it
comes from the bobbin, _g_, which turns freely upon the tube _a_. The
top of this bobbin is conical and toothed. A small catch or detent, _h_,
moveable in a vertical direction round _i_, falls by its own weight into
the teeth of the crown of the bobbin, in which case this cannot revolve;
but when the detent is raised so far as to disengage the teeth, and at
the same time to pull the thread, the bobbin turns, and lets out thread
till the detent falls back into these same teeth.

A skewer of iron wire, _k_, is loaded with a small weight, _l_, melted
upon it. The top of this skewer has an eye in it, and the bottom is
recurved as is shown in _fig._ 158., so that supposing the thread comes
to break, this skewer falls into the actual position in the figure,
where we see its lower end extending beyond the tube _a_, by about 1/4
of an inch; but as long as the thread is unbroken, the skewer _k_, which
serves to keep it always tense, during the eccentric movement of the
puppet, does not pass out below the tube.

This disposition has naturally furnished the means of causing the
machine to stop, whenever one of the threads breaks. This inferior
protrusion of the skewer pushes in its progress a detent, which
instantly causes the band to slide from the driving pulley to the loose
pulley. Thus the machine cannot operate unless all the threads be
entire. It is the business of the operative, who has 3 or 4 under her
charge, to mend the threads as they break, and to substitute full
bobbins for empty ones, whenever the machine is stopped.

The braiding frame, though it does not move quickly, makes a great deal
of noise, and would make still more, were the toothed wheels made of
metal instead of wood. For them to act well, they should be made with
the greatest precision, by means of appropriate tools for forming the
teeth of the wheels, and the other peculiar parts.


BRAN. (_Son_, Fr.; _Kleie_, Germ.) The husky portion of ground wheat,
separated by the boulter from the flour. It is advantageously employed
by the calico printers, in the clearing process, in which, by boiling in
bran-water, the colouring matters adhering to the non-mordanted parts of
maddered goods, as well as the dun matters which cloud the mordanted
portions, are removed. A valuable series of researches concerning the
operation of bran in such cases was made a few years ago by that
distinguished chemist and calico printer, M. Daniel Kœchlin-Schouch, and
published in the ninth number of the Bulletin de la Société Industrielle
de Mulhausen. Nine sets of experiments are recorded, which justified the
following conclusions.

1. The dose of two bushels of bran for 10 pieces of calico is the best,
the ebullition being kept up for an hour. A boil for the same time in
pure water had no effect in clearing either the grounds or the figures.

2. Fifteen minutes boiling are sufficient when the principal object is
to clear white grounds, but in certain cases thirty minutes are
requisite to brighten the dyed parts. If, by increasing the charge of
bran, the time of the ebullition could be shortened, it would be in some
places, as Alsace, an economy; because for the passage of ten pieces
through a copper or vat heated with steam, 1 cwt. of coal is consumed in
fuel which costs from 2-1/2 to 3 francs, while two bushels of bran are
to be bought for one franc.

3. By increasing the quantity of water from 12 to 24 hectolitres with
two bushels of bran, the clearing effect upon the ten pieces was
impaired. It is therefore advantageous not to use too much water.

4. Many experiments concur to prove that flour is altogether useless for
the clearing boil, and that finer bran is inferior for this purpose to
the coarser.

5. The white ground of the calicoes boiled with wheat bran, are
distinguishable by their superior brightness from that of those boiled
with rye bran, and especially with barley bran; the latter having hardly
any effect.

6. There is no advantage in adding soap to the bran boil; though a
little potash or soda may be properly introduced when the water is
calcareous.

7. The pellicle of the bran is the most powerful part, the flour and the
starch are of no use in clearing goods, but the mucilage which forms one
third of the weight of the bran has considerable efficacy, and seems to
act in the following way. In proportion as the mucilaginous substance
dissolves the colouring and tawny matters upon the cloth, the husky
surface attracts and fixes upon itself the greater part of them.
Accordingly, when used bran is digested in a weak alkaline bath, it
gives up the colour which it had absorbed from the cloth.

The following chemical examination of bran is interesting. A pound of it
was boiled at successive times with water, the decoctions being
filtered, let fall in cooling a greyish deposit, which was separated by
decantation. The clear liquor afforded by evaporation to dryness four
ounces of a brownish, brittle matter, composed chiefly of mucilage, a
little gluten, and starch. The gray deposit of the above filtered liquor
amounted to half an ounce. Nine ounces of the cortical portion of the
bran were obtained. The loss amounted to 2-1/2 ounces, being in some
measure the hygrometric water of the bran itself.

When boiled with distilled water, goods are cleared pretty well without
bran. Certain delicate dyes must be boiled only a few minutes in a
strong decoction of bran previously made.


BRANDY. The name given in this country to ardent spirits distilled from
wine, and possessed of a peculiar taste and flavour, due to a minute
portion of a peculiar volatile oil. Each variety of alcohol has an aroma
characteristic of the fermented substance from which it is procured;
whether it be the grape, cherries, sugar-cane, rice, corn, or potatoes;
and it may be distinguished even as procured from different growths of
the vine. The brandies of Languedoc, Bordeaux, Armagnac, Cognac, Aunis,
Saintonge, Rochelle, Orleans, Barcelona, Naples, &c. being each readily
recognisable by an experienced dealer.

Aubergier showed, by experiments, that the disagreeable taste of the
spirits distilled from the _marc_ of the grape is owing to an essential
oil contained in the skin of the grape; and found that the oil, when
insulated, is so energetic that a few drops are sufficient to taint a
pipe of 600 litres of fine-flavoured spirit.

The most celebrated of the French brandies, those of Cognac and
Armagnac, are slightly rectified to only from 0·935 to 0·922; they
contain more than half their weight of water, and come over therefore
highly charged with the fragrant essential oil of the husk of the grape.
When, to save expense of carriage, the spirit is rectified to a much
higher degree, the dealer, on receiving it at Paris, reduces it to the
market proof by the addition of a little highly-flavoured weak brandy
and water; but he cannot in this way produce so finely-flavoured a
spirit, as the weaker product of distillation of the Cognac wine. If the
best Cognac brandy be carefully distilled at a low heat, and the strong
spirit be diluted with water, it will be found to have suffered much in
its flavour.

Genuine French brandy evinces an acid reaction with litmus paper, owing
to a minute portion of vinegar; it contains besides some acetic ether,
and, when long kept in oak casks, a little astringent matter. The
following formula may be proposed for converting a silent or flavourless
corn spirit, into a factitious brandy. Dilute the pure alcohol to the
proof pitch, add to every hundred pounds weight of it from half a pound
to a pound of argol (crude winestone) dissolved in water, a little
acetic ether, and French-wine vinegar, some bruised French plums, and
flavour-stuff from Cognac; then distil the mixture with a gentle fire,
in an alembic furnished with an agitator.

The spirit which comes over may be coloured with nicely burned sugar
(caramel) to the desired tint, and roughened in taste with a few drops
of tincture of catechu or oak-bark.

The above recipe will afford a spirit free from the deleterious drugs
too often used to disguise and increase the intoxicating power of
British brandies; one which may be reckoned as wholesome as alcohol, in
any shape, can ever be.


BRASS. (_Laiton_, _cuivre jaune_, Fr.; _Messing_, Germ.) An alloy of
copper and zinc. It was formerly manufactured by cementing granulated
copper, called _bean-shot_, or copper clippings, with calcined calamine
(native carbonate of zinc) and charcoal, in a crucible, and exposing
them to bright ignition. Three parts of copper were used for three of
calamine and two of charcoal. The zinc reduced to the metallic state by
the agency of the charcoal, combined with the copper, into an alloy
which formed, on cooling, a lump at the bottom of the crucible. Several
of these, being remelted and cast into moulds, constituted ingots of
brass for the market. James Emerson obtained a patent, in 1781, for
making brass by the direct fusion of its two metallic elements, and it
is now usually manufactured in this way.

It appears that the best proportion of the constituents to form fine
brass is one prime equivalent of copper = 63-1/2 + one of zinc = 32·3;
or very nearly 2 parts of copper to 1 of zinc. The bright gold coloured
alloy, called Prince’s, or Prince Rupert’s metal, in this country,
consists apparently of two primes of zinc to one of copper, or of nearly
equal parts of each. Brass, or hard solder, consists of two parts of
brass and one of zinc melted together, to which a little tin is
occasionally added; but when the solder must be very strong, as for
brass tubes that are to undergo drawing, two thirds of a part of zinc
are used for two parts of brass. Mosaic gold, according to the
specification of Parker and Hamilton’s patent consists of 100 parts of
copper, and from 52 to 55 of zinc; which is no atomic proportion. Bath
metal is said to consist of 32 parts of brass and 9 parts of zinc.

The button manufacturers of Birmingham make their _platin_ with 8 parts
of brass and 5 of zinc; but their cheap buttons with an alloy of copper,
tin, zinc, and lead.

Red brass, the Tombak of some, (not of the Chinese, for this is white
copper,) consists of more copper and less zinc than go to the
composition of brass; being from 2-1/2 to 8 or 10 of the former to 1 of
the latter. At the famous brass works of Hegermühl, to be presently
described, 11 parts of copper are alloyed with 2 of zinc into a red
brass, from which plates are made that are afterwards rolled into
sheets. From such an alloy the Dutch foil, as it is called, is
manufactured at Nürnberg; Pinchbeck, Similor, Mannheim gold, are merely
different names of alloy similar to Prince’s metal. The last consists of
3 of copper and 1 of zinc, separately melted, and suddenly incorporated
by stirring.--_Wiegleb._

In the process of alloying two metals of such different fusibilities as
copper and zinc, a considerable waste of the latter metal by the
combustion, to which it is so prone, might be expected; but, in reality,
their mutual affinities seem to prevent the loss, in a great measure, by
the speedy absorption of the zinc into the substance of the copper.
Indeed, copper plates and rods are often _brassed_ externally by
exposure, at a high temperature, to the fumes of zinc, and afterwards
laminated or drawn. The spurious gold wire of Lyons is made from such
rods. Copper vessels may be superficially converted into brass by
boiling them in dilute muriatic acid, containing some winestone and zinc
amalgam.

The first step in making brass is to plunge slips of copper into melted
zinc till an alloy of somewhat difficult fusion be formed, to raise the
heat, and add the remaining proportion of the copper.

The brass of the first fusion is broken to pieces, and melted with a
fresh quantity of zinc, to obtain the finished brass. Each melting takes
about 8 or 9 hours. The metal is now cast into plates, about 40 inches
long by 26 inches broad, and from one third to one half inch thick. The
moulds are, in this case also, slabs of granite mounted in an iron
frame. Granite appears to be preferred to every thing else as a mould,
because it preserves the heat long, and by the asperities of its
surface, it keeps hold of the clay lute applied to secure the joinings.

The cast plates are most usually rolled into sheets. For this purpose
they are cut into ribands of various breadths, commonly about 6-1/2
inches. The cylinders of the brass rolling-press are generally 46 inches
long, and 18 inches in diameter. The ribands are first of all passed
cold through the cylinders; but the brass soon becomes too hard to
laminate. It is then annealed in a furnace, and, after cooling, is
passed afresh through a rolling press. After paring off the chipped
edges, the sheets are laminated two at a time: and if they are to be
made very thin, even eight plates are passed through together. The brass
in these operations must be annealed 7 or 8 times before the sheet
arrives at the required thinness. These successive heatings are very
expensive; and hence they have led the manufacturers to try various
plans of economy. The annealing furnaces are of two forms according to
the size of the sheets of brass. The smaller are about 12 feet long,
with a fire place at each end, and about 13 inches wide. The arch of the
furnace has a cylindrical shape, whose axis is parallel to its small
side. The hearth is horizontal, and is made of bricks set on edge. In
the front of the furnace there is a large door, which is raised by a
lever, or chain, and counterweight, and slides in a frame between two
cheeks of cast iron. This furnace has, in general, no chimney, except a
vent slightly raised above the door, to prevent the workmen being
incommoded by the smoke. Sometimes the arch is perforated with a number
of holes. The sheets of brass are placed above each other, but separated
by parings, to allow the hot air to circulate among them, the lowest
sheet resting upon two bars of cast iron placed lengthwise.

The large furnaces are usually 32 feet long, by 6-1/2 feet wide, in the
body, and 3 feet at the hearth. A grate, 13 inches broad, extends along
each side of the hearth, through its whole length, and is divided from
it by a small wall, 2 or 3 inches high. The vault of the furnace has a
small curvature, and is pierced with 6 or 8 openings, which allow the
smoke to pass off into a low bell-chimney above. At each end of the
furnace there is a cast-iron door, which slides up and down in an iron
frame, and is poised by a counterweight. On the hearth there is a kind
of railway, composed of two iron bars, on the grooves of which the
carriage moves with its loads of sheets of brass.

These sheets, being often 24 feet long, could not be easily moved in and
out of the furnace; but as brass laminates well in the cold state, they
are all introduced and moved out together. With this view, an iron
carriage is framed with four bars, which rest on four wheels. Upon this
carriage, of a length nearly equal to that of the furnace, the sheets
are laid, with brass parings between them. The carriage is then raised
by a crane to a level with the furnace, and entered upon the grooved
bars which lie upon the hearth. That no heat may be lost, two carriages
are provided, the one being ready to put in as the other is taken out;
the furnace is meanwhile uniformly kept hot. This method, however
convenient for moving the sheets in and out, wastes a good deal of fuel
in heating the iron carriage.

The principal places in which brass is manufactured on the great scale
in England, are Bristol, Birmingham, and Holywell, in North Wales.

The French writers affirm, that a brass, containing 2 _per cent._ of
lead, works more freely in the turning lathe, but does not hammer so
well as the mere alloy of copper and zinc.

At the brass manufactory of Hegermühl, upon the Finon canal near
Potsdam, the following are the materials of one charge; 41 pounds of old
brass, 55 pounds refined copper (gahrkupfer) granulated; and 24 pounds
of zinc. This mixture, weighing 120 pounds, is distributed into four
crucibles, and fused in a wind furnace with pitcoal fuel. The waste
varies from 2-1/2 to 4 pounds upon the whole.

[Illustration: 159 160]

_Fig._ 159. represents the furnace as it was formerly worked there with
charcoal; _a_, the laboratory in which the crucibles were placed. It was
walled with fire bricks. The foundations and the filling-in walls were
formed of stone rubbish, as being bad conductors of heat; sand and ashes
may be also used; _b_, cast-iron circular grating plates pierced with
12 holes (see _fig._ 160.), over them a sole of loam, _c_, is beat down,
and perforated with holes corresponding to those in the iron discs; _d_,
the ash-pit; _e_, the _bock_, a draught flue which conducts the air
requisite to the combustion, from a sunk tunnel, in communication with
several melting furnaces. The terrace or crown of the furnace, _f_, lies
on a level with the foundry floor, _h h_, and is shut with a tile of
fire-clay, _g_, which may be moved in any direction by means of hooks
and eyes in its binding iron ring. _Fig._ 161. the tongs for putting in
and taking out the charges, as viewed from above and from the side.

[Illustration: 161 162 163]

_Figs._ 162, 163. represent the furnaces constructed more recently for
the use of pitcoal fuel; _fig._ 162. being an upright section, and
_fig._ 163. the ground plan. In this furnace the crucibles are not
surrounded with the fuel, but they receive the requisite melting heat
from the flame proceeding from the grate upon which it is burned. The
crucibles stand upon 7 binding arches, _a_, which unite in the middle at
the key-stone _b_, _fig._ 163. Between the arches are spaces through
which the flame rises from the grate _c_. _d_ is the fire-door; _e_, a
sliding tile or damper for regulating or shutting off the air-draught;
_f_ an inclined plane, for carrying off the cinders that fall through
the grate, along the draught tunnel _g_, so that the air in entering
below may not be heated by them.

The crucibles are 16 inches deep, 9-1/2 wide at the mouth, 6-1/2 at the
bottom; with a thickness in the sides of 1 inch and 1-1/2 below; they
stand from 40 to 50 meltings. The old brass, which fills their whole
capacity, is first put in and melted down; the crucibles are now taken
out, and are charged with the half of the zinc in pieces of from 1 to 3
cubic inches in size, covered over with coal ashes; then one half of the
copper charge is introduced, again coal-dust; and thus the layers of
zinc and copper are distributed alternately with coal-ashes betwixt
them, till the whole charge gets finally fused. Over all, a thicker
layer of carbonaceous matter is laid, to prevent oxidizement of the
brass. Eight crucibles filled in this way are put into the furnace
between the 11 holes of the grate shelf; and over them two empty
crucibles are laid to be heated for the casting operation. In from 3-1/2
to 4 hours the brass is ready to be poured out. Fifteen English bushels
of coals are consumed in one operation; of which six are used at the
introduction of the crucibles, and four gradually afterwards.

When sheet brass is to be made the following process is pursued:--

An empty crucible, called a _caster_ (_giesser_), is taken out of the
furnace through the crown with a pair of tongs, and is kept red hot by
placing it in a hollow hearth (_mundal_), surrounded with burning coals;
into this crucible the contents of four of the melting pots are poured;
the dross being raked out with an iron scraper. As soon as the melting
pot is emptied, it is immediately re-charged in the manner above
described, and replaced in the furnace. The surface of the melted brass
in the _caster_ is swept with the stump of a broom, then stirred about
with the iron rake, to bring up any light foreign matter to the surface,
which is then skimmed with a little scraper; the crucible is now seized
with the casting tongs, and emptied in the following way:--

[Illustration: 164 165]

The mould or _form_ for casting sheet brass consists of two slabs of
granite, _a a_, _figs._ 164, 165. They are 5-1/2 feet long; 3 feet
broad, 1 foot thick, and, for greater security, girt with iron bands, _b
b_, 2 inches broad, 1-1/2 thick, and joined at the four corners with
bolts and nuts. The mould rests upon an oaken block, _c_, 3-1/2 feet
long, 2-1/6 broad, and 1-1/4 thick, which is suspended at each end upon
gudgeons, in bearing blocks, placed under the foundery floor, _d d_, in
the casting pit, _e e_. This is lined with bricks; and is 6-3/4 feet
long, 5-1/2 broad, and 2 deep; upon the two long side walls of the pit,
the bearing blocks are laid, which support the gudgeons. The
swing-blocks are 10 inches long, 18 inches broad, 15 inches thick, and
are somewhat rounded upon their back edge, so that the casting frame may
slope a little to the horizon. To these blocks two cross wooden arms, _f
f_, are mortised, upon which the under slab rests, freely, but so as to
project about 5 inches backwards over the block, to secure an equipoise
in the act of casting. _g g_ are bars, placed at both of the long sides,
and one of the ends, between the slabs, to determine the thickness of
the brass-plate. Upon the other slab the gate _h_ is fastened, a sheet
of iron 6 inches broad, which has nearly the shape of a parallel
trapezium (lozenge), and slopes a little towards the horizon. It serves
for setting the casting pot upon in the act of pouring out, and renders
its emptying more convenient. That gate (_steinmaul_) is coated with a
mixture of loam and hair. The upper slab is secured to the under one in
its slanting position by an _armour_ or binding. This consists of the
tension bars of wood, _i k l m_, of the iron bars _n_, (3 to 3-1/2
inches broad, 1-1/2 inch thick, see the top view, _fig._ 165.) of a rod
with holes and pins at its upper end, and of the iron screw spindle _o_.
The mode in which these parts act may be understood from inspection of
the figure. In order to lift the upper slab from the under one, which is
effected by turning it round its edge, a chain is employed, suspending
two others, connected with the slab. The former passes over a pulley,
and may be pulled up and down by means of a wheel and axle, or with the
aid of a counterweight. Upon each of the two long sides of the slab
there are two iron rings, to which the ends of the chains may be hooked.
The casting faces of the slab must be coated with a layer of finely
ground loam; the thinner the better.

When calamine is employed, 1/2 cwt. of copper, 3/4 cwt. of calamine, and
1/3 the volume of both of charcoal mixed, are put into 7 crucibles, and
exposed to heat during 11 or 12 hours; the product being from 70 to 72
lbs. of brass.

_Brass-plate rolling._--At Hegermühl there are two re-heating or
annealing furnaces, one larger, 18 feet long, and another smaller,
8-1/2; the hot chamber is separated from the fire place by iron beams,
in such a way that the brass castings are played upon by the flames on
both their sides. After each passage through the laminating press
(rolls) they are heated anew, then cooled and laminated afresh, till
they have reached the proper length. The plates are besmeared with
grease before rolling.

[Illustration: 166 167 168]

_Fig._ 166. shows the ground plan of the furnace and its railway; _fig._
167. the cross section; and _fig._ 168. the section lengthwise; _a a_,
the iron way bars or rails upon the floor of the foundry, for enabling
the wheels of the waggon-frame to move readily backwards and forwards;
_b b_, the two grates; _c c_, the ash pits; _d d_, the fire beams; _e e
e_, vents in the roof of the hot chamber _f_; _g g_, two plates for
shutting the hot chamber; _h_, the flue; _i_, the chimney. After the
rolling, the sheets covered with a black oxide of copper, are plunged
into a mother water of the alum works for a few minutes, then washed in
clean water, and lastly, smeared with oil and scraped with a blunt
knife.

In rough brass and brass wares, no less than 16,240 cwts. were
manufactured in the Prussian States in the year 1832.

For musical purposes, the brass wire made in Berlin, has acquired great
and merited celebrity; but that of Birmingham is now preferred even by
foreigners.

BRASS COLOUR, for staining glass, is prepared by exposing for several
days thin plates of brass upon tiles in the _leer_ or annealing arch of
the glass-house, till it be oxidized into a black powder, aggregated in
lumps. This being pulverized and sifted, is to be again well calcined
for several days more, till no particles remain in the metallic state;
when it will form a fine powder of a russet brown colour. A third
calcination must now be given, with a carefully regulated heat; its
quality being tested from time to time by fusion with some glass. If it
makes the glass swell, and intumesce, it is properly prepared; if not,
it must be still farther calcined. Such a powder communicates to glass,
greens of various tints, passing into turquoise.

When thin narrow strips of brass are stratified with sulphur in a
crucible, and calcined at a red heat, they become friable, and may be
reduced to powder. This being sifted and exposed upon tiles in a
reverberatory furnace for ten or twelve days, becomes fit for use, and
is capable of imparting a calcedony, red or yellow tinge to glass by
fusion, according to the mode and proportion of using it.

The glass-makers’ red colour may be prepared by exposing small plates of
brass to a moderate heat in a reverberatory furnace, till they are
thoroughly calcined, when the substance becomes pulverulent, and assumes
a red colour. It is then ready for immediate use.

BRASS COLOUR, as employed by the colourmen to imitate brass, is of two
tints, the red or bronze, and the yellow like gilt brass. Copper filings
mixed with red ochre or bole, constitute the former; a powdered brass
imported from Germany is used for the latter. Both must be worked up
with varnish after being dried with heat, and then spread with a flat
camel-hair brush evenly upon the surface of the object. The best varnish
is composed of 20 ounces of spirits of wine, 2 ounces of shellac, and 2
ounces of sandarach, properly dissolved. See VARNISH. Only so much of
the brass powder and varnish should be mixed at a time as is wanted for
immediate use.

BRASS FOIL. Dutch leaf, called _Knitter_ or _Rauschgold_ in Germany, is
made from a very thin sheet brass, beat out under a hammer worked by
water power, which gives 300 or 400 strokes per minute; from 40 to 80
leaves being laid over each other. By this treatment it acquires its
characteristic solidity and lustre. See above, the process for
converting the copper superficially into brass by the fumes of zinc.


BRAZING. (_Braser_, Fr.; _Messing-lothung_, Germ.) The soldering
together of edges of iron, copper, brass, &c., with an alloy consisting
of brass and zinc, sometimes with a little tin or silver. The surfaces
to be thus united must be filed perfectly bright, and not be soiled with
the fingers or in any other way. The granular or nearly pulverulent
alloy is usually wetted with a paste of ground borax and water, applied
in this state, dried, and then exposed carefully to bright ignition at a
clear forge fire. Some workmen enclose the part to be soldered in a clay
lute, but others prefer leaving it uncovered, that they may see when the
solder has flowed freely, and entered into all the seams.


BRAZIL-WOOD. (_Bois de Fernambouc_, Fr.; _Brasilienholz_, Germ.) This
dye-wood derives its name from the part of America whence it was first
imported. It has also the names Fernambuca, wood of Saint Martha, and of
Sapan, according to the places which produce it. Linnæus distinguishes
the tree which furnishes the Brazil wood by the name of _Cæsalpinia
crista_. It commonly grows in dry places among rocks. Its trunk is very
large, crooked, and full of knots. It is very hard, susceptible of a
fine polish, and sinks in water. It is pale when newly cleft, but
becomes red on exposure to the air.

It has different shades of red and orange. Its goodness is determined
particularly by its density. When chewed, a saccharine taste is
perceived. It may be distinguished from red saunders wood, as the latter
does not yield its colour to water.

Boiling water extracts the whole colouring matter of Brazil-wood. If the
ebullition be long enough continued, it assumes a fine red colour. The
residuum appears black. In this case, an alkali may still extract much
colouring matter. The solution in alcohol or ammonia is still deeper
than the preceding.

The decoction of Brazil-wood, called juice of Brazil, is observed to be
less fit for dyeing when recent, than when old or even fermented. By age
it takes a yellowish-red colour. For making this decoction, Hellot
recommends to use the hardest water; but it should be remarked, that
this water deepens the colour in proportion to the earthy salts which it
contains. After boiling this wood reduced to chips, or, what is
preferable, to powder, for three hours, this first decoction is poured
into a cask. Fresh water is poured on the wood, which is then made to
boil for three hours, and mixed with the former. When Brazil-wood is
employed in a dyeing bath, it is proper to enclose it in a thin linen
bag, as well as all the dye woods in general.

Wool immersed in the juice of Brazil takes but a feeble tint, which is
speedily destroyed. It must receive some preparations.

The wool is to be boiled in a solution of alum, to which a fourth or
even less of tartar is added, for a larger proportion of tartar would
make the colour yellowish. The wool is kept impregnated with it for at
least eight days, in a cool place. After this, it is dyed in the Brazil
juice with a slight boiling. But the first colouring particles that are
deposited, afford a less beautiful colour; hence it is proper to pass a
coarser stuff previously through the bath. In this manner a lively red
is procured, which resists pretty well the action of the air.

Brazil-wood is made use of for dyeing silk what is called false crimson,
to distinguish it from the crimson made by means of cochineal, which is
much more permanent.

The silk should be boiled at the rate of 20 parts of soap per cent., and
then alumed. The aluming need not be so strong as for the fine crimson.
The silk is refreshed at the river, and passed through a bath more or
less charged with Brazil juice, according to the shade to be given. When
water free from earthy salts is employed, the colour is too red to
imitate crimson; this quality is given it by passing the silk through a
slight alkaline solution, or by adding a little alkali to the bath. It
might, indeed, be washed in a hard water till it had taken the desired
shade.

To make deeper false crimsons of a dark red, juice of logwood is put
into the Brazil bath after the silk has been impregnated with it. A
little alkali may be added, according to the shade that is wanted.

To imitate poppy or flame colour, an annotto ground is given to the
silk, deeper even than when it is dyed with carthamus. It is washed,
alumed, and dyed with juice of Brazil, to which a little soap water is
usually added.

The colouring particles of Brazil wood are easily affected, and made
yellow by the action of acids.

They thus become permanent colours. But what distinguishes them from
madder and kermes, and approximates them to cochineal, is their
reappearing in their natural colour, when they are thrown down in a
state of combination with alumina, or with oxide of tin. These two
combinations seem to be the fittest for rendering them durable. It is
requisite, therefore, to inquire what circumstances are best calculated
to promote the formation of these combinations, according to the nature
of the stuff.

The astringent principle, likewise, seems to contribute to the
permanence of the colouring matter of Brazil wood; but it deepens its
hue, and can only be employed for light shades.

The colouring particles of Brazil wood are very sensible to the action
of alkalies which give them a purple hue; and there are several
processes in which the alkalies, either fixed or volatile, are used for
forming violets and purples. But the colours obtained by these methods,
which may be easily varied according to the purpose, are perishable, and
possess but a transient bloom. The alkalies appear not to injure the
colours derived from madder, but they accelerate the destruction of most
other colours.

In England and Holland the dye-woods are reduced to powder by means of
mills erected for the purpose.

The bright fugitive red, called fancy red, is given to cotton by
Nicaragua, or peachwood, a cheap kind of Brazil wood.

The cotton being scoured and bleached, is boiled with sumach. It is then
impregnated with a solution of tin (at 5° Baumé, according to Vitalis).
It should now be washed slightly in a weak bath of the dyeing wood, and
lastly, worked in a somewhat stale infusion of the peach or Brazil wood.
When the temperature of this is lukewarm, the dye is said to take
better. Sometimes two successive immersions in the bath are given. It is
now wrung out, aired, washed in water, and dried.

M. Vitalis says, that his solution of tin is prepared with two ounces of
tin and a pound of aqua regia made with two parts of nitric acid at 24°
Baumé, and three parts of muriatic acid at 22°.

For a rose colour, the cotton is alumed as usual, and washed from the
alum. It then gets the tin mordant, and is again washed. It is now
turned through the dye-bath, an operation which is repeated if
necessary.

For purple a little alum is added to the Brazil bath.

1. For amaranth, the cotton is strongly galled, dried, and washed.

2. It is passed through the black cask (tonneau noir), see BLACK DYE,
till it has taken a strong grey shade.

3. It receives a bath of lime water.

4. Mordant of tin.

5. Dyeing in the Brazil wood bath.

6. The two last operations are repeated.

Dingler has endeavoured to separate the colouring matter of the
different sorts of Brazil wood, so as to obtain the same tint from the
coarser as from the best Pernambuco. His process consists in treating
the wood with hot water or steam, in concentrating the decoction so as
to obtain 14 or 15 pounds of it from 4 pounds of wood, allowing it to
cool, and pouring into it two pounds of skim milk; agitating, then
boiling for a few minutes, and filtering. The dun colouring matters are
precipitated by the coagulation of the caseous substance. For dyeing,
the decoctions must be diluted with water; for printing they must be
concentrated, so that 4 pounds of wood shall furnish only 5 or 6 pounds
of decoction, and the liquor may be thickened in the ordinary way. These
decoctions may be employed immediately, as by this treatment they have
acquired the same property as they otherwise could get only by being
long kept. A slight fermentation is said to improve the colour of these
decoctions; some ground wood is put into the decoction to favour this
process.

As gelatine produces no precipitate with these decoctions, they
consequently contain no tannin. Gall-nuts, however, sumach, the bark of
birch or alder, render the colour of Brazil wood more durable, upon
alumed linen and cotton goods, but the shade is a little darker.

In dyeing wool with Pernambuco, the temperature of the bath should never
be above 150° Fahr., since higher heats impair the colour.

According to Dingler and Kurrer, bright and fast scarlet reds may be
obtained upon wool, by preparing a decoction of 50 pounds of Brazil wood
in three successive boils, and setting the decoction aside for 3 or 4
weeks in a cool place; 100 pounds of the wool are then alumed in a bath
of 22 pounds of alum and 11 pounds of tartar, and afterwards rinsed in
cold water. Meanwhile we fill two-thirds with water, a copper containing
30 pails, and heated to the temperature of 150° or 160° F. We pour in 3
pailfuls of the decoction, heat to the same point again, and introduce
30 pounds of wool, which does not take a scarlet, but rather a crimson
tint. This being removed, 2 pails of decoction are put in, and 30 pounds
of wool which becomes scarlet, but not so fine as at the third dip. If
the dyer strengthens the colour a little at the first dip, a little more
at the second, and adds at the third and fourth the quantity of
decoction merely necessary, he will obtain an uniform scarlet tint. With
50 pounds of Pernambuco 1000 pounds of wool may be dyed scarlet in this
way, and with the deposits another 100 may be dyed of a tile colour. An
addition of weld renders the colour faster but less brilliant.

Karkutsch says the dye may be improved by adding some ox-gall to the
bath.

In dyeing cotton the tannin and gallic acid are two necessary mordants,
and the colour is particularly bright and durable, when the cloth has
been prepared with the oily process of Turkey red.

It is said that stale urine heightens the colour of the Brazil dye when
the ground wood is moistened with it.

The quantity of Brazil or Nicaragua wood imported into the United
Kingdom in 1835, was 6,242 tons, whereof 1,811 were exported; of
Brazilietto 230 tons. The duty upon the first article is 5_s._ per ton.


BREAD (_Pain_, Fr.; _Brod_, Germ.) is the spongy mass produced by baking
the leavened or fermented dough of wheat or rye flour, at a proper heat.
It is the principal food of highly civilized nations. The skilful
preparation of this indispensable article constitutes the art of the
Baker. Dough baked without being fermented constitutes cakes or
biscuits; but not bread strictly speaking.

Pliny informs us, that barley was the only species of corn at first used
for food; and even after the method of reducing it to flour had been
discovered, it was long before mankind learned the art of converting it
into cakes.

Ovens were first invented in the East. Their construction was understood
by the Jews, the Greeks, and the Asiatics, among whom baking was
practised as a distinct profession. In this art, the Cappadocians,
Lydians, and Phœnicians, are said to have particularly excelled. It was
not till about 580 years after the foundation of Rome, that these
artisans passed into Europe. The Roman armies, on their return from
Macedonia, brought Grecian bakers with them into Italy. As these bakers
had handmills beside their ovens, they still continued to be called
_pistores_, from the ancient practice of bruising the corn in a mortar;
and their bakehouses were denominated _pistoriæ_. In the time of
Augustus there were no fewer than 329 public bakehouses in Rome; almost
the whole of which were in the hands of Greeks, who long continued the
only persons in that city acquainted with the art of baking good bread.

In nothing, perhaps, is the wise and cautious policy of the Roman
government more remarkably displayed, than in the regulations which it
imposed on the bakers within the city. To the foreign bakers who came to
Rome with the army from Macedonia, a number of freedmen were associated,
forming together an incorporation from which neither they nor their
children could separate, and of which even those who married the
daughters of bakers were obliged to become members. To this
incorporation were entrusted all the mills, utensils, slaves, animals,
every thing, in short, which belonged to the former bakehouses. In
addition to these, they received considerable portions of land; and
nothing was withheld, which could assist them in pursuing, to the best
advantage, their highly prized labours and trade. The practice of
condemning criminals and slaves, for petty offences, to work in the
bakehouse, was still continued; and even the judges of Africa were bound
to send thither, every five years, such persons as had incurred that
kind of chastisement. The bakehouses were distributed throughout the
fourteen divisions of the city, and no baker could pass from one into
another without special permission. The public granaries were committed
to their care; they paid nothing for the corn employed in baking bread
that was to be given in largess to the citizens; and the price of the
rest was regulated by the magistrates. No corn was given out of these
granaries except for the bakehouses, and for the private use of the
prince. The bakers had besides private granaries, in which they
deposited the grain, which they had taken from the public granaries for
immediate use; and if any of them happened to be convicted of having
diverted any portion of the grain to another purpose, he was condemned
to a ruinous fine of five hundred pounds weight of gold.

Most of these regulations were soon introduced among the Gauls; but it
was long before they found their way into the more northern countries of
Europe. Borrichius informs us that in Sweden and Norway, the only bread
known, so late as the middle of the 16th century, was unleavened cakes
kneaded by the women. At what period in our own history the art of
baking became a separate profession, we have not been able to ascertain;
but this profession is now common to all the countries in Europe, and
the process of baking is also nearly the same.

The French, who particularly excel in the art of baking, have a great
many different kinds of bread. Their _pain bis_, or brown bread, is the
coarsest kind of all, and is made of coarse groats mixed with a portion
of white flour. The _pain bis blanc_, is a kind of bread between white
and brown, made of white flour and fine groats. The _pain blanc_, or
white bread, is made of white flour, shaken through a sieve after the
finest flour has been separated. The _pain mollet_, or soft bread, is
made of the purest flour without any admixture. The _pain chaland_, or
customers’ bread, is a very white kind of bread, made of pounded paste.
_Pain chapelé_, is a small kind of bread, with a well-beaten and very
light paste, seasoned with butter or milk. This name is also given to a
small bread, from which the thickest crust has been removed by a knife.
_Pain cornu_, is a name given by the French bakers to a kind of bread
made with four corners, and sometimes more. Of all the kinds of small
bread, this has the strongest and firmest paste. _Pain à la reine_,
queen’s bread, _pain à la Sigovie_, _pain chapelé_, and _pain cornu_,
are all small kinds of bread, differing only in the lightness or
thickness of the paste. _Pain gruau_ is a small very white bread made
now in Paris, from the flour separated after a slight grinding from the
best wheat. Such flour is in hard granular particles.

In this country we have fewer varieties of bread, and these differ
chiefly in their degrees of purity. Our white or fine bread is made of
the purest flour; our wheaten bread, of flour with a mixture of the
finest bran; and our household bread, of the whole substance of the
grain without the separation either of the fine flour or coarse bran. We
have also symnel bread, manchet or roll bread, and French bread, which
are all made of the purest flour from the finest wheat; the roll bread
being improved by the addition of milk, and the French bread by the
addition of eggs and butter. To these may be added gingerbread, a cake
made of flour, with almonds, liquorice, aniseed, rose-water, and sugar
or treacle; and mastlin bread, made of wheat and rye, or sometimes of
wheat and barley. We have various kinds of small bread, having various
names, according to their various forms. They are, in general, extremely
light, and are sweetened with sugar, currants, and other palatable
ingredients. In Scotland there is a cake called _short bread_, made from
a pretty thick dough, enriched with butter, sweetened with sugar, and
seasoned with orange peel, or other kinds of spices.

The process of making bread is nearly the same in all the countries of
modern Europe; though the materials of which it as composed vary with
the farinaceous productions of different climates and soils. The flour
of wheat is most generally employed for this purpose, wherever that
vegetable can be reared. This flour is composed of a small portion of
mucilaginous saccharine matter, soluble in cold water, from which it may
be separated by evaporation; of a great quantity of starch, which is
scarcely soluble in cold water, but capable of combining with that fluid
by means of heat; and an adhesive gray substance called gluten,
insoluble in water, ardent spirit, oil, or ether, and resembling an
animal substance in many of its properties. Flour kneaded with water,
forms a tough rather indigestible paste containing all the constituent
parts which we have enumerated. Heat produces a considerable change on
the glutinous part of this compound, and renders it more easy of
mastication and digestion. Still, however, it continues heavy and tough,
compared with bread which is raised by leaven or yeast. Leaven is
nothing more than a piece of dough, kept in a warm place till it
undergoes a process of fermentation; swelling, becoming spongy, or full
of air bubbles, at length disengaging an acidulo-spirituous vapour, and
contracting a sour taste. When this leaven is mingled in proper
proportions with fresh-made dough, it makes it rise more readily and
effectually than it would do alone, and gives it at the same time a
greater degree of firmness. Upon the quality of the leaven employed, the
quality of the bread materially depends.

The principal improvement which has been made on bread in modern times,
is the substitution of yeast or barm in place of common leaven. This
yeast is the viscid froth that rises to the surface of beer, in the
first stage of its fermentation. When mixed with the dough, it makes it
rise much more speedily and effectually than ordinary leaven, and the
bread is of course much lighter, and freer from that sour and
disagreeable taste which may often be perceived in bread raised with
leaven, either because too much is mingled with the paste, or because it
has been allowed to advance too far in the process of fermentation.

Bread properly raised and baked, differs materially from unleavened
cakes, not only in being less compact and heavy, and more agreeable to
the taste, but in losing its tenacious and glutinous qualities, and thus
becoming more salutary and digestible.

We possess several analyses of wheat flour. Ordinary wheat (_triticum
hybernum mixed with triticum turgidum_) contains, according to the
analyses made by Vauquelin of several species of wheat flour, the
following substances:--

  +--------------------------+------+-------+-------+------+
  |                          |      |       |       |      |
  | Species of Wheat.        |Water.|Gluten.|Starch.|Sugar.|
  |                          |      |       |       |      |
  +--------------------------+------+-------+-------+------+
  |French wheat flour        | 10·0 | 10·96 | 71·49 | 4·72 |
  |Hard wheat of Odessa flour| 12·0 | 14·55 | 56·50 | 8·48 |
  |Soft wheat of Odessa flour| 10·0 | 12·00 | 62·00 | 7·56 |
  |Same sort of flour        |  8·0 | 12·10 | 70·84 | 4·90 |
  |Same sort of flour        | 12·0 |  7·30 | 72·00 | 5·42 |
  |Wheat of the French bakers| 10·0 | 10·20 | 72·80 | 4·20 |
  |Flour of the Paris hos-   |  8·0 | 10·30 | 71·20 | 4·80 |
  |pitals (2d quality)       |      |       |       |      |
  |Ditto (3d quality)        | 12·0 |  9·02 | 67·78 | 4·80 |
  +--------------------------+------+-------+-------+------+

  +--------------------------+------+-----+------+------+
  |                          |      |     |      |Water |
  | Species of Wheat.        | Gum. |Bran.|Total.| of   |
  |                          |      |     |      |dough.|
  +--------------------------+------+-----+------+------+
  |French wheat flour        | 3·32 |  -  |100·49| 50·3 |
  |Hard wheat of Odessa flour| 4·90 | 2·3 | 98·73| 51·2 |
  |Soft wheat of Odessa flour| 5·80 | 1·2 | 98·42| 54·8 |
  |Same sort of flour        | 4·60 |  -  |100·41| 37·4 |
  |Same sort of flour        | 3·30 |  -  |100·02| 37·2 |
  |Wheat of the French bakers| 2·80 |  -  |100·00| 40·6 |
  |Flour of the Paris hos-   | 3·60 |  -  | 97·90| 37·8 |
  |pitals (2d quality)       |      |     |      |      |
  |Ditto (3d quality)        | 4·60 | 2·0 |100·21| 37·8 |
  +--------------------------+------+-----+------+------+

The following table of analyses merits also a place here.

  +------------------+------+-------+-------+------+-------+-----+-----+
  |Species of Flour. |Water.|Gluten.|Starch.|Sugar.|Gummi- |Albu-|Bran.|
  |                  |      |       |       |      |gluten.|men. |     |
  +------------------+------+-------+-------+------+-------+-----+-----+
  |Flour of the      |   1  | 22·   | 74·   |  5·50| 1·    | 1·50|     |
  |triticum spelta   |      |       |       |      |       |     |     |
  |Ditto triticum    |   1  | 24·   | 68·   |  5·0 | 1·    | 1·50|     |
  |hybernum          |      |       |       |      |       |     |     |
  |Ditto common wheat|   -  | 12·5  | 74·5  | 12·  | 2·    |     |     |
  |Ditto wheat and   |   6  |  9·80 | 75·50 |  4·22| 3·28  |  -  | 1·2 |
  |rye mixed         |      |       |       |      |       |     |     |
  |(mastlin)         |      |       |       |      |       |     |     |
  +------------------+------+-------+-------+------+-------+-----+-----+

The first two of the above analyses were made by Vogel, the third by
Proust, and the fourth by Vauquelin.

Analyses of the flour of some other corns.

  +---------+-------+-----+----+-----+---------+-------------+-----+
  |Species  |Starch.|Muci-|Glu-|Albu-|  Sugar. |    Husk.    |Hor- |
  |of Flour.|       |lage.|ten.|men. |         |             |dein.|
  +---------+-------+-----+----+-----+---------+-------------+-----+
  |         |       |     |    |     |         |Of a fat oil,|     |
  |White    | 59·00 | 2·5 | -  |4·30 |  8·25   |     2       |     |
  |oatmeal  |       |     |    |     |Of resin,|             |     |
  |Barley   | 32·00 | 9·  | 3· | -   |   2     |     -       | 55  |
  |meal     |       |     |    |     |         |             |     |
  +---------+-------+-----+----+-----+---------+-------------+-----+

The first analysis is by Vogel, the second by Proust.

It deserves to be remarked, that the flour of Odessa contains a much
greater quantity of sugar than the French flour. The substance indicated
in the preceding table by the name of gluten, is the gluten of Beccaria,
that is to say, a mixture of gluten and vegetable albumen. The gum of
wheat is not quite identical with ordinary gum. It is a brown azotised
substance, which, when treated by nitric acid, affords no mucic acid,
but oxalic acid and the bitter principle of Welter. It contains besides
superphosphate of lime.

The last column of the first table exhibits the quantity of water
necessary to convert the flour into dough of the ordinary consistence,
and it is usually proportional to the quantity of gluten. The hard wheat
of Odessa forms an exception in this respect; the reason of the
difference being that the starch contained in this flour is not as in
ordinary flour in a fine powder, but in small transparent grains, which
resemble pounded gum, and absorb less water than pulverulent starch.

The _triticum monococcon_, according to Zenneck, contains in its
unsifted flour, 16·334 of gluten and vegetable albumen; 64·838 of
starch; 11·347 of gum, sugar, and extractive; 7·481 of husks. The sifted
flour affords 15·536 of gluten and vegetable albumen; 76·459 of starch;
7·198 of sugar, gum, and extractive; 0·807 of husky matter. It is
difficult to conceive how such great quantities of gluten, albumen, and
extractive matter, could disappear in the sifting. The triticum spelta
contains in 100 parts of the finest flour, 22·5 of a soft and humid
gluten, mixed with vegetable albumen; 74 of starch, and 5·5 of sugar.
Here we have an excess of 2 parts in the 100.

Wheat furnishes very little ashes by incineration, not more than 0·15
per cent. of the weight; containing superphosphates of soda, lime, and
magnesia.

The object of baking is to combine the gluten and starch of the flour
into a homogeneous substance, and to excite such a vinous fermentative
action, by means of its saccharine matter, as shall disengage abundance
of carbonic acid gas in it for making an agreeable, soft, succulent,
spongy, and easily digestible bread. The two evils to be avoided in
baking are, hardness on the one hand, and pastiness on the other.
Well-made bread is a chemical compound, in which the gluten and starch
cannot be recognized or separated, as before, by a stream of water. When
flour is kneaded into a dough, and spread into a cake, this cake, when
baked, will be horny if it be thin, or if thick, will be tough and
clammy; whence we see the value of that fermentative process, which
generates thousands of little cells in the mass or crumb, each of them
dry, yet tender and succulent, through the intimate combination of the
moisture. By this constitution it becomes easily soluble in the juices
of the stomach, or in other words, light of digestion. It is moreover
much less liable to turn sour than cakes made from unfermented dough.

Rye, which also forms a true spongy bread, though inferior to that of
wheat, consists of similar ingredients; namely, 61·07 of starch; 9·48 of
gluten; 3·28 of vegetable albumen; 3·28 of uncrystallizable sugar; 11·09
of gum; 6·38 of vegetable fibre; the loss upon the 100 parts amounted to
5·62, including an acid whose nature the analyst, M. Einhof, did not
determine. Rye flour contains also several salts, principally the
phosphates of lime and magnesia. This kind of grain forms a
dark-coloured bread reckoned very wholesome; comparatively little used
in this country, but very much in France, Germany, and Belgium.

Dough fermented with the aid either of leaven or yeast, contains little
or none of the saccharine matter of the flour, but in its stead a
certain portion, nearly half its weight, of spirit, which imparts to it
a vinous smell, and is volatilized in the oven; whence it might be
condensed into a crude weak alcohol, on the plan of Mr. Hick’s patent,
were it worth while. But the increased complexity of the baking
apparatus, will probably prove an effectual obstacle to the commercial
success of this project, upon which already upwards of 20,000_l._
sterling have been squandered.

That the sugar of the flour is the true element of the fermentation
preposterously called panary, which dough undergoes, and that the starch
and gluten have nothing to do with it, may be proved by decisive
experiments. The vinous fermentation continues till the whole sugar is
decomposed, and no longer; when if the process be not checked by the
heat of baking, the acetous fermentation will supervene. Therefore if a
little sugar be added to a flour which contains little or none, its
dough will become susceptible of fermenting, with extrication of gas, so
as to make spongy succulent bread. But since this sponginess is produced
solely by the extrication of gas, and its expansion in the heat of the
oven, any substance capable of emitting gas, or of being converted into
it under these circumstances, will answer the same purpose. Were a
solution of bicarbonate of ammonia obtained by exposing the common
sesqui-carbonate in powder for a day to the air, incorporated with the
dough, in the subsequent firing it will be converted into vapour, and in
its extrication render the bread very porous. Nay, if water highly
impregnated with carbonic acid gas be used for kneading the dough, the
resulting bread will be somewhat spongy. Could a light article of food
be prepared in this way, then as the sugar would remain undecomposed,
the bread would be so much the sweeter, and the more nourishing. How far
a change propitious to digestion takes place in the constitution of the
starch and gluten, during the fermentative action of the dough, has not
been hitherto ascertained by precise experiments. Medical practitioners,
who derive an enormous revenue from dyspepsia, should take some pains
to investigate this subject.

Dr. Colquhoun, in his able essay upon the art of making bread, has shown
that its texture when prepared by a sudden formation and disengagement
of elastic fluid generated within the oven, differs remarkably from that
of a loaf which has been made after the preparatory fermentation with
yeast. Bread which has been raised with the common carbonate of ammonia
as used by the pastry-cooks, is porous no doubt, but not spongy with
vesicular spaces, like that made in the ordinary way. The former kind of
bread never presents that air-cell stratification which is the boast of
the Parisian baker, but which is almost unknown in London. I have found
it moreover very difficult to expel by the oven the last portion of the
ammonia, which gives both a tinge and a taste to the bread. I believe,
however, that the bicarbonate would be nearly free from this objection,
which operates so much against the sesqui-carbonate of the shops.

In opposition to Mr. Edlin’s account of the excellent quality of bread
made by impregnating dough with carbonic acid gas[10], Dr. Colquhoun
adduces Vogel’s experiments, which show that such dough, when baked,
after having been kept in a warm situation during the usual time,
afforded nothing better than a hard cake, which had no resemblance to
common bread. Vogel further states, as illustrative of the general
necessity of providing a sufficient supply of disengaged elastic fluid
within the dough, before baking it at all, that when he made various
attempts to form a well-raised vesicular loaf, within the oven, by
mixing flour with carbonate of magnesia, or with zinc filings, and then
kneading it into a paste by means of water, acidulated with sulphuric
acid, he always met with complete failure and disappointment. Dr.
Colquhoun performed a series of well-devised experiments on this
subject, which fully confirmed Vogel’s results, and prove that a proper
spongy bread cannot be made by the agency of either carbonic acid water,
or of mixtures of sesqui-carbonate of soda, and tartaric acid. The bread
proved doughy and dense in every case, though less so with the latter
mixture than the former. No loaf bread can, indeed, be well made by any
of these two extemporaneous systems, because they are inconsistent with
the thorough kneading of the dough. It is this process which renders
dough at once elastic enough to expand when carbonic acid gas is
generated within it, and cohesive enough to confine the gas when it is
generated. The whole gas of the loaf is disengaged in its interior by a
continuous fermentation, after all the processes of kneading have been
finished; for the loaf, after being kneaded, weighed out, and shaped, is
set aside till it expands gradually to double its bulk, before it is put
into the oven. But when a dough containing sesqui-carbonate of soda is
mixed with one containing muriatic acid, in due proportions to form the
just dose of culinary salt, the gas escapes during the necessary
incorporation of the two, and the bread formed from it is dense and
hard. Dr. Whiting has, however, made this old chemical process the
subject of a new patent for baking bread.

  [10] Treatise on the Art of Bread Making, p. 56.

When the baker prepares his dough, he takes a portion of the water
needed for the batch, having raised its temperature to from 70° to 100°
F., dissolves a certain proportion of his salt in it, then adds the
yeast, and a certain quantity of his flour. This mixture, called the
_sponge_, is next covered up in the small kneading-trough, alongside of
the large one, and let alone for _setting_ in a warm situation. In about
an hour, signs of vinous fermentation appear, by the swelling and
heaving up of the sponge, in consequence of the generation of carbonic
acid; and if it be of a semi-liquid consistence, large air bubbles will
force their way to the surface, break, and disappear in rapid
succession. But when the _sponge_ has the consistence of thin _dough_,
it confines the gas, becomes thereby equably and progressively inflated
to double its original volume; when no longer capable of containing the
pent-up air, it bursts and subsides. This process of rising and falling
alternately might be carried on during twenty-four hours, but the baker
has learned by experience to guard against allowing full scope to the
fermentative principle. He generally interferes after the first, or at
furthest after the second or third dropping of the sponge; for were he
not to do so, the bread formed with such dough would invariably be found
sour to the taste and the smell. Therefore he adds at this stage to the
sponge the reserved proportions of flour, salt, and water, which are
requisite to make the dough of the desired consistence and size; and
next incorporates the whole together by a long and laborious course of
kneading. When this operation has been continued till the fermenting and
the fresh dough have been intimately blended, and till the glutinous
matter of both is worked into such union and consistence that the mass
becomes so tough and elastic as to receive the smart pressure of the
hand without adhering to it, the kneading is suspended for some time.
The dough is now abandoned to itself for a few hours, during which it
continues in a state of active fermentation throughout its entire mass.
Then it is subjected to a second but much less laborious kneading, in
order to distribute the generated gas as evenly as possible among its
parts, so that they may all partake equally of the vesicular structure.
After this second kneading, the dough is weighed out into the portions
suitable to the size of bread desired; which are of course shaped into
the proper forms, and once more set aside in a warm situation. The
continuance of the fermentation soon disengages a fresh quantity of
carbonic acid gas, and expands the lumps to about double their pristine
volume. These are now ready for the oven, and when they finally quit it
in the baked state, are about twice the size they were when they went
in. The generation of the due quantity of gas should be complete before
the lumps are transferred to the oven; because whenever they encounter
its heat, the process of fermentation is arrested; for it is only the
previously existing air which gets expanded throughout every part of the
loaf, swells out its volume, and gives it the _piled_ and vesicular
texture. Thus the well-baked loaf is composed of an infinite number of
cellules filled with carbonic acid gas, and apparently lined with a
glutinous membrane of a silky softness. It is this which gives the
light, elastic porous constitution to bread.

After suffering the fermentative process to exhaust itself in a mass of
dough, and the dough to be brought into that state in which the addition
of neither yeast, nor starch, nor gluten will produce any effect in
restoring that action, if we mix in 4 per cent. of saccharine matter, of
any kind, with a little yeast, the process of fermentation will
immediately re-commence, and pursue a course as active and lengthened as
at first, and cease about the same period.[11]

  [11] Dr. Colquhoun, in Annals of Philosophy for 1826, vol. xii. p.
  171.

This experiment, taken in connection with the facts formerly stated,
proves that what was called panary fermentation, is nothing but the
ancient and well-known process of the vinous fermentation of sugar,
which generates alcohol. There seems to be but one objection to the
adoption of this theory. After the loaf is baked, there is found in its
composition nearly as much saccharine matter as existed in the flour
before fermentation. M. Vogel states that in the baked bread there
remains 3·6 parts of sugar, out of the 5 parts which it originally
contained. Thus, in 100 parts of loaf bread prepared with wheaten flour,
distilled water, and yeast without the admixture of any common salt, he
found the following ingredients:--

  Sugar                                    8·6
  Torrefied or gummy starch               18·0
  Starch                                  53·5
  Gluten, combined with a little starch,  20·75

  Exclusive of carbonic acid, muriate of lime, phosphate of lime, &c.

It must be borne in mind that in every loaf the process of fermentation
has been prematurely checked by the baker’s oven, and therefore the
saccharine constituent can never be wholly decomposed. It seems certain,
also, that by the action of gluten upon the starch in the early stage of
the firing, a quantity of sugar will be formed by the saccharine
fermentation; which we have explained in treating of BEER.

Several masses of dough were prepared by Dr. Colquhoun in which pure
wheat starch was mixed with common flour, in various proportions. In
some of the lumps this starch had been gelatinized, with the _minimum_
of hot water, before it was added to the flour. After introducing the
usual dose of salt, the dough was thoroughly kneaded, set apart for the
proper period, allowed to ferment in the accustomed way, and then baked
in the oven. In outward appearance, increase of bulk, and vesicular
texture, none of them differed materially from a common loaf, baked
along with them for the sake of comparison; except that when the starch
considerably exceeded the proportion of flour in the lump, the loaf,
though whiter, had not risen so well, being somewhat less vesicular.
But, on tasting the bread of each loaf, those which contained most
gelatinized starch were unexpectedly found to be the sweetest. The other
loaves, into which smaller quantities of the gelatinized starch had been
introduced, or only some dry starch, had no sweetish taste whatever to
distinguish them from ordinary bread. These facts seem to establish the
conclusion, that the presence of gelatinous starch in bread put into the
oven, is a means of forming a certain portion of saccharine matter
within the loaf, during the baking process. Now it is more than probable
that gelatinized starch does exist, more or less, in all loaves which
have been fermented by our usual methods, and hence a certain quantity
of sugar will necessarily be generated at its expense, by the action of
heat. Thus the difficulty started by M. Vogel is sufficiently solved;
and there remains no doubt that, in the saccharine principle of flour,
the fermentation has its origin and end, while dough is under
fermentation.

The source of the sourness which supervenes in bread, under careless or
unskilful hands, had been formerly ascribed to each of all the
constituents of flour; to its gluten, its starch, and its sugar; but
erroneously, as we now see: for it is merely the result of the second
fermentation which always succeeds the vinous, when pushed improperly
too far. It has been universally taken for granted by authors, that the
acid thus generated in dough is the acetic. But there appear good
grounds to believe that it is frequently a less volatile acid, probably
the lactic, particularly when the process has been tardy, from the
imperfection of the yeast or the bad quality of the flour. The
experiments of Vogel, Braconnot, and others, prove that the latter acid
is generated very readily, and in considerable quantity during the
spontaneous decomposition of a great many vegetable substances, when in
a state of humidity. The presence of lactic acid would account for the
curious fact, that the acidity of unbaked dough is much more perceptible
to the taste than to the smell; while the sourness of the same piece of
bread, after coming out of the oven, is, on the contrary, much more
obvious to the olfactory organs than to the palate. But this is exactly
what ought to happen, if the lactic acid contributes, in conjunction
with the acetic, to produce the acescence of the dough. At the ordinary
temperature of a bakehouse, the former acid, though very perceptible in
the mouth, is not distinguishable by the nostrils; but as it is easily
decomposed by heat, no sooner is it exposed to the high temperature of
the oven, than it is resolved, in a great measure, into acetic acid[12],
and thus becomes more manifest to the sense of smell, and less to that
of taste. This theory seems to explain satisfactorily all the phenomena
accompanying the progress of fermentation in baker’s dough, and also
some of its results in the process of baking which do not easily admit
of any other solution.

  [12] Berzelius.

There are extremely simple and effectual methods for enabling the baker
to adopt measures either to prevent or correct the evil of acescence,
and these are to neutralize the acid by the due exhibition of an alkali,
such as soda; or an alkaline earth, such as magnesia or chalk. And it
affords a striking proof of how much the artisan has been accustomed to
plod, uninquiring and uninformed, over the same ground, that a remedy so
safe and so economical, should remain at this day unthought of and
unemployed by most of the manufacturers of bread in the United Kingdom.
The introduction of a small portion of carbonate of soda will rectify
any occasional error in the result of the so called panary fermentation,
and will, in fact, restore the dough to its pristine sweetness. The
quantity of acetate of soda, which will be thus present in the bread,
will be altogether inconsiderable; and as it has no disagreeable taste,
and is merely aperient to the bowels in a very mild degree, it can form
no objection in the eye of the public police. The restoration of dough
thus tainted with acid, and its conversion into pleasant and wholesome
bread, has been sufficiently verified by experiment. But, according to
Mr. Edmund Davy, carbonate of magnesia may be used with still greater
advantage, as during the slow action of the acid upon it, the carbonic
acid evolved serves to open up and lighten bread which would otherwise
be dense and doughy from the indifferent quality of the flour. Here,
however, the dangerous temptation lies with a sordid baker to use cheap
or damaged flour, and to rectify the bread made of it by chemical
agents, innocent in themselves, but injurious as masks of a bad raw
material. When sour yeast must be used, as sometimes happens with the
country bakers, or in private houses at a distance from beer breweries,
there can be no harm, but, on the contrary, much propriety, in
correcting its acidity, by the addition of as much carbonate of soda to
it as will effect its neutralization, but nothing more. When sour yeast
has been thus corrected, it has been found, in practice, to possess its
fermentative power unimpaired, and to be equally efficacious, with fresh
formed yeast, in making good palatable loaves.

We have seen that, in baking, about one fourth of the starch is
converted into a matter possessing the properties of _British gum_ (see
STARCH), and also that the gluten, though not decomposed, has its
particles disunited, and is not so tough and adhesive as it is in the
flour. This principle is also, as we have said, useful in cementing all
the particles of the dough into a tenacious mass, capable of confining
the elastic fluid generated by the vinous fermentation of the sugar.
Starch is the main constituent, the basis of nourishment in bread, as
well as in all farinaceous articles of food. The albumen also of the
wheat being coagulated by the heat of the oven, contributes to the
setting of the bread into a consistent elastic body.

In the mills in the neighbourhood of London, no less than seven distinct
sorts of flour are ground out of one quantity of wheat. These are for
one quarter--

  Fine flour        5 bushels 3 pecks.
  Seconds           0         2
  Fine middlings    0         1
  Coarse middlings  0         0·5
  Bran              3         0
  Twenty-penny      3         0
  Pollard           2
                   ---        ---
                   14         2·5

So that we have nearly a double bulk of flour, or 14 bushels and 2-1/2
pecks from 8 bushels of wheat. In the sifting of the flour through the
bolter, there is a fine white angular meal obtained called sharps, which
forms the central part of the grain. It is consumed partly by the fine
biscuit bakers. The bakers of this country were formerly bound by law to
bake three kinds of bread, the _wheaten_, _standard wheaten_, and the
_household_; marked respectively with a W, S W, and H, and if they
omitted to make these marks on their bread they were liable to a
penalty. The size of the loaves were usually peck, half-peck, quartern,
and half-quartern; the weights of which, within 48 hours of their being
baked, should have been respectively 17 lbs. 6 oz.; 8 lbs. 11 oz.; 4
lbs. 5 oz. 8 dr.; and 4 lbs. 2 oz. 14 dr. In general they weigh about
one-seventh more before they enter the oven, or they lose one-seventh of
their weight in baking. The French bread loses fully one-sixth in the
oven, owing chiefly to its more oblong thin shape, as compared to the
cubical shape of the English bread. But this loss of weight is very
variable, being dependent upon the quality of the wheaten flour, and the
circumstances of baking. The present law in England defines the quartern
loaf at 4 lbs., and subjects the baker to a penalty if the bread be one
ounce lighter than the standard. Hence it leaves the baker in
self-defence, to leave it in rather a damp and doughy state. But there
is much light bread sold in London. I have met with quartern loaves of 3
lbs. 10 ozs. A sack of flour weighing 280 lbs. was presumed by the
framers of our former parliamentary acts, for the assize of bread, to be
capable of being baked into 80 loaves. If this proportion had been
correct, one-fifth part of our quartern loaf must consist of water and
salt, and four-fifths of flour. But in general, of good wheaten flour,
three parts will take up one part of water; so that the sack of flour
should have turned out, and actually did turn out, more than 80 loaves.
At present with 4 lb. bread it may well yield 92 loaves.

The following statement of the system of baking at Paris, I received in
1835 from a very competent judge of the business.

1,000 kilogrammes of wheat = 5 quarters English, cost 200 fr., and yield
800 kilos of flour of the best white quality, equivalent to 5-1/10 sacks
French. Hence the sack of flour costs 40 francs at the mill, and
including the carriage to Paris, it costs 45 or 46 francs.

The profit of the flour dealer is about 3-1/2 francs, and the sale price
becomes from 43 to 50 francs.

  _Bread manufactured from the above._

                                       _£_ _s._ _d._   _£_ _s._ _d._
  One day’s work of an ordinary baker,                  6   0    0
  who makes fourbatches in a day,
  consists of 3 sacks at 50 francs, or
  2_l._ sterling each
  Salt 2-3/4 lbs. at 2_d._ per lb.                      0   0    5-1/2
  Yeast or leaven 3 lbs. at 5_d._                       0   1    3
                                                       ---------------
  Total cost of materials                               6   1    8-1/2

  _Expenses of Baking._

  Three workmen at different rates of   0   12   0
  wages, 15 francs
  Fire-wood 0, as the charcoal pro-
  duced pays for it
  General expenses, such as rent,       0   12   0
  taxes, interest of capital, &c.
                                        ----------
                                        1    4   0  =   1   4    0
                                                        --------------
                                                        7   5    8-1/2

  For this sum 315 loaves are made,                     7  17    6
  being 105 for every sack of flour
  weighing 156·66 kilos, or 344-2/3
  lbs. avoird. One loaf contains
  therefore 344·65/105 = 3·282 lbs.,
  and as 100 lbs. of flour in Parisian
  baking are reckoned to produce 127
  lbs. of bread, each loaf will weigh
  4·168 lbs., avoird., and will cost
  7_l._ 5_s._ 8-1/2_d._ divided by 315
  = 5-1/2_d._ very nearly. The value
  of 315 loaves at the sale price of
  6_d._ will be
                                                        --------------
  Upon this day’s work the clear                        0  11    9-1/2
  profit is therefore

A new baking establishment has been recently formed at the Royal
Clarence Victualling Establishment at Weevil, near Portsmouth, upon a
scale of magnitude nearly sufficient to supply the whole royal navy with
biscuits, and that of a very superior description. The following account
of it is taken from the United Service Journal. “It having been
discovered that the flour supplied to government by contract, had in
many instances been most shamefully adulterated, the corn is ground at
mills comprised within the establishment, by which means the
introduction of improper ingredients is prevented, and precisely the
proportion of bran which is requisite in the composition of good
sea-biscuit is retained, and no more. The flour-mill is furnished with
10 pairs of stones, by which 40 bushels of flour may be ground and
dressed ready for baking, in an hour. The baking establishment consists
of 9 ovens, each 13 feet long by 11 feet wide, and 17-1/2 inches in
height. These are each heated by separate furnaces, so constructed that
a blast of hot air and fire sweeps through them, and gives to the
interior the requisite dose of heat in an incredible short space of
time. The first operation in making the biscuits, consists in mixing the
flour or rather meal and water; 13 gallons of water are first introduced
into a trough, and then a sack of the meal, weighing 280 lbs. When the
whole has been poured in by a channel communicating with an upper room,
a bell rings, and the trough is closed. An apparatus consisting of two
sets of what are called knives, each set ten in number, are then made to
revolve amongst the flour and water by means of machinery. This mixing
operation lasts one minute and a half, during which time the double
set of knives or stirrers makes twenty-six revolutions. The next
process is to cast the lumps of dough under what are called the
breaking-rollers,--huge cylinders of iron, weighing 14 cwt. each, and
moved horizontally by the machinery along stout tables. The dough is
thus formed into large rude masses 6 feet long by 3 feet broad, and
several inches thick. At this stage of the business, the kneading is
still very imperfect, and traces of dry flour may still be detected.
These great masses of dough are now drawn out, and cut into a number of
smaller masses about a foot and a half long by a foot wide, and again
thrust under the rollers, which is repeated until the mixture is so
complete that not the slightest trace of any inequality is discoverable
in any part of the mass. It should have been stated that two workmen
stand one at each side of the rollers, and as the dough is flattened
out, they fold it up, or double one part upon another, so that the
roller at its next passage squeezes these parts together, and forces
them to mix. The dough is next cut into small portions, and being placed
upon large flat boards, is, by the agency of machinery, conveyed from
the centre to the extremity of the baking-room. Here it is received by a
workman, who places it under what is called the sheet roller, but which,
for size, colour, and thickness, more nearly resembles a blanket. The
kneading is thus complete, and the dough only requires to be cut into
biscuits before it is committed to the oven. The cutting is effected by
what is called the cutting-plate, consisting of a net-work of 52
sharp-edged hexagonal frames, each as large as a biscuit. This frame is
moved slowly up and down by machinery, and the workman, watching his
opportunity, slides under it the above-described blanket of dough, which
is about the size of a leaf of a dining table; and the cutting-frame in
its descent indents the sheet, but does not actually cut it through, but
leaves sufficient substance to enable the workman at the mouth of the
oven to jerk the whole mass of biscuits unbroken into it. The dough is
prevented sticking to the cutting-frame by the following ingenious
device: between each of the cutter-frames is a small flat open frame,
movable up and down, and loaded with an iron ball, weighing several
ounces. When the great frame comes down upon the dough, and cuts out 52
biscuits, each of these minor frames yields to the pressure, and is
raised up; but as soon as the great frame rises, the weight of the balls
acting upon the little frames, thrusts the whole blanket off, and allows
the workmen to pull it out. One quarter of an hour is sufficient to bake
the biscuit, which is afterwards placed for three days in a drying room,
heated to 85° or 90°, which completes the process.” The following
statement of the performance of the machinery is taken from actual
experiment; in 116 days, during 68 of which, the work was continued for
only 7-1/2 hours; and during 48, for only 5-3/4 hours each day, in all
769 working hours, equal to 77 days of 10 hours each; the following
quantity of biscuit was baked in the 9 ovens; viz., 12,307 cwt. =
1,378,400 lbs. The wages of the men employed in baking this quantity
amounted to 273_l._ 10_s._ 9-1/2_d._; if it had been made by hand, the
wages would have been 933_l._ 9_s._ 10_d._; saving in the wages of
labour, 659_l._ 7_s._ 0-1/2_d._ In this, is not included any part of the
interest of the sum laid out upon the machine, or expended in keeping it
in order. But in a very few years at such an immense rate of saving, the
cost of the engine and other machinery will be repaid. This admirable
apparatus is the invention of T. T. Grant, Esq. storekeeper of the Royal
Clarence Victualling Establishment, who, we believe, has been properly
rewarded, by a grant of 2,000_l._ from government.

The labour of incorporating the ingredients of bread, viz. flour, water
and salt, or kneading dough, is so great as to have led to the
contrivance of various mechanical modes of producing the same effect.
One of the most ingenious is that for which a patent was obtained in
August, 1830, by Mr. Edwin Clayton. It consists of a rotatory kneading
trough, or rather barrel, mounted in bearings with a hollow axle, and of
an interior frame of cast iron made to revolve by a solid axle which
passes through the hollow one; in the frame there are cutters diagonally
placed for kneading the dough. The revolving frame and its barrel are
made to turn in contrary directions, so as greatly to save time and
equalize the operation. This double action represents kneading by the
two hands, in which the dough is inverted from time to time, torn
asunder, and reunited in every different form. The mechanism will be
readily understood from the following description.

[Illustration: 169]

_Fig._ 169. exhibits a front elevation of a rotatory kneading trough,
constructed according to improvements specified by the patentee, the
barrel being shown in section: _a_ is the barrel, into which the several
ingredients, consisting of flour, water, and yeast, are put, which
barrel is mounted in the frame-work _b_, with hollow axles _c_ and _d_,
which hollow axles turn in suitable bearings at _e_; _f_ is the
revolving frame which is mounted in the interior of the barrel _a_, by
axles _g_ and _h_. The ends of this revolving frame are fastened, or
braced together by means of the oblique cutters or braces _i_, which act
upon the dough when the machine is put in motion, and thus cause the
operation of kneading.

Either the barrel may be made to revolve without the rotatory frame, or
the rotatory frame without the barrel, or both may be made to revolve
together, but in opposite ways. These several motions may be obtained by
means of the geer-work, shown at _k_, _l_, and _m_, as will be presently
described.

If it be desired to have the revolving motion of the barrel and rotatory
frame together, but in contrary directions, that motion may be obtained
by fastening the hollow axle of the wheel _m_, by means of a screw _n_,
to the axle _h_, of the rotatory frame _f_, tight, so as they will
revolve together, the other wheels _k_ and _l_ being used for the
purpose of reversing the motion of the barrel. It will then be found
that by turning the handle _o_, the two motions will be obtained.

If it be desired to put the rotatory frame _f_, only into motion, that
action will be obtained by loosening the screw _n_, upon the axle of the
wheel _m_, when it will be found that the axle _h_, will be made to
revolve freely by means of the winch _o_, without giving motion to the
wheels _k_, _l_, and _m_, and thus the barrel will remain stationary. If
the rotatory action of the barrel be wanted, it will be obtained by
turning the handle _p_, at the reverse end of the machine, which,
although it puts the geer at the opposite end of the barrel into motion,
yet as the hollow axle of the wheel _m_ is not fastened to the axle _h_,
by the screw _n_, these wheels will revolve without carrying round the
frame _f_.

M. Kuhlmann, Professor of Chemistry at Lille, having been called upon
several times by the courts of justice to examine by chemical processes
bread suspected of containing substances injurious to health, collected
some interesting facts upon the subject, which were published under the
direction of the central council of salubrity of the department _du
Nord_.

For some time public attention had been drawn to an odious fraud
committed by a great many bakers in the north of France and in
Belgium,--the introduction of a certain quantity of sulphate of copper
into their bread. When the flour was made from bad grain this
adulteration was very generally practised, as was proved by many
convictions and confessions of the guilty persons. When the dough does
not rise well in the fermentation (_le pain pousse plat_), this
inconvenience was found to be obviated by the addition of blue vitriol,
which was supposed also to cause the flour to retain more water. The
quantity of blue water added is extremely small, and it is never done in
presence of strangers, because it is reckoned a valuable secret. It
occasions no economy of yeast, but rather the reverse. In a litre (about
a quart) of water, an ounce of sulphate of copper is dissolved; and of
this solution a wine-glass full is mixed with the water necessary for 50
quartern or 4 pound loaves.

M. Kuhlmann justly observes that there can be no safety whatever to the
public when such a practice is permitted, because ignorance and avarice
are always apt to increase the quantity of the poisonous water. In
analyses made by him and his colleagues, portions of bread were several
times found so impregnated with the above salt that they had acquired a
blue colour, and presented occasionally even small crystals of the
sulphate. By acting on the poisoned bread with distilled water and
testing the water with ferro-cyanate (prussiate) of potash, the reddish
brown precipitate or tint characteristic of copper will appear even with
small quantities. Should the noxious impregnation be still more minute,
the bread should be treated with a very dilute nitric-acid, either
directly, or after incineration in a platinum capsule, and the solution,
when concentrated by evaporation, should be tested by the ferro-cyanate
of potash. In this way, a one seventy thousandth part of sulphate of
copper may be detected.

M. Kuhlmann deduces, from a series of experiments on baking with various
small quantities of sulphate of copper, that this salt exercises an
extremely energetic action upon the fermentation and rising of the
dough, even when not above one seventy thousandth part of the weight of
the bread is employed; or one grain of sulphate for ten pounds of bread.
The proportion of the salt which makes the bread rise best is one twenty
thousandth, or one grain in three pounds of bread. If much more of the
sulphate be added, the bread becomes moist, less white, and acquires a
peculiar disagreeable smell like that of leaven. The increase of weight
by increased moisture may amount to one sixteenth without the bread
appearing softer, in consequence of the solidifying quality of the
copper; for the acid does not seem to have any influence; as neither
sulphate of soda, sulphate of iron, nor sulphuric acid have any
analogous power. Alum operates like blue vitriol on bread, but larger
quantities of it are required. It _keeps water_, and _raises well_, to
use the bakers’ terms.

When alum is present in bread it may be detected by treating the bread
with distilled water, filtering the water first through calico, and next
through filtering paper, till it becomes clear; then dividing it into
two portions, and into the one pouring a few drops of nitrate or muriate
of barytes, and into the other a few drops of water of ammonia. In the
former a heavy white precipitate indicating sulphuric acid will appear,
and in the latter a light precipitate of alumina, redissoluble by a few
drops of solution of caustic potash.

When chalk or Paris plaster is used to sophisticate flour, they may be
best detected by incinerating the bread made of it, and examining the
ashes with nitric acid which will dissolve the chalk with effervescence,
and the Paris plaster without. In both cases the calcareous matter may
be demonstrated in the solution, by oxalic acid, or better by oxalate of
ammonia.

In baking puff-paste the dough is first kneaded along with a certain
quantity of butter, then rolled out into a thin layer, which is coated
over with butter, and folded face-wise many times together, the upper
and under surfaces being made to correspond. This stratified mass is
again rolled out into a thin layer, its surface is besmeared with
butter, and then it is folded face-wise as before. When this process is
repeated ten or a dozen times, the dough will consist of many hundred
parallel laminæ, with butter interposed between each pair of plates.
When a moderately thick mass of this is put into the oven, the elastic
vapour disengaged from the water and the butter, diffuses itself between
each of the thin laminæ, and causes them to swell into what is properly
called puff-paste, being an assemblage of thin membranes, each dense in
itself, but more or less distinct from the other, and therefore forming
apparently but not really light bread.

One of the most curious branches of the baker’s craft is the manufacture
of gingerbread, which contains such a proportion of molasses, that it
cannot be fermented by means of yeast. Its ingredients are flour,
molasses or treacle, butter, common potashes, and alum. After the butter
is melted, and the potashes and alum are dissolved in a little hot
water, these three ingredients, along with the treacle, are poured among
the flour, which is to form the body of the bread. The whole is then
incorporated by mixture and kneading into a stiff dough. Of these five
constituents the alum is thought to be the least essential, although it
makes the bread lighter and crisper, and renders the process more rapid;
for gingerbread dough requires to stand over several days, sometimes 8
or 10, before it acquires that state of porosity which qualifies it for
the oven. The action of the treacle and alum on the potashes in evolving
carbonic acid, seems to be the gasefying principle of gingerbread; for
if the carbonate of potash is withheld from the mixture, the bread, when
baked, resembles in hardness a piece of wood.

Treacle is always acidulous. Carbonate of magnesia and soda may be used
as substitutes for the potashes. Dr. Colquhoun has found that carbonate
of magnesia and tartaric acid may replace the potashes and the alum with
great advantage, affording a gingerbread fully more agreeable to the
taste, and much more wholesome than the common kind, which contains a
notable quantity of potashes. His proportions are one pound of flour, a
quarter of an ounce of carbonate of magnesia, and one eighth of an ounce
of tartaric acid; in addition to the treacle, butter, and aromatics as
at present used. The acid and alkaline earth must be well diffused
through the whole dough. The magnesia should, in fact, be first of all
mixed with the flour. Pour the melted butter, the treacle, and the acid
dissolved in a little water all at once among the flour, and knead into
a consistent dough, which being set aside for half an hour or an hour
will be ready for the oven, and should never be kept unbaked more than 2
or 3 hours. The following more complete recipe is given by Dr.
Colquhoun, for making thin gingerbread cakes:--

  Flour                 1     lb.
  Treacle               0-1/2
  Raw sugar             0-1/4
  Butter                2     oz.
  Carbon. magnesia      0-1/4
  Tartaric acid         0-1/8
  Ginger                0-1/8
  Cinnamon              0-1/8
  Nutmeg                1

This compound has rather more butter than common thin gingerbread.

I shall here insert a passage from my Dictionary of Chemistry as
published in 1821; as it may prove interesting to many of my present
readers.

“Under _Process of Baking_, in the Supplement to the Encyclopedia
Britannica, we have the following statement:--‘An ounce of alum is then
dissolved over the fire in a tin pot, and the solution poured into a
large tub, called by the bakers the seasoning-tub. Four pounds and a
half of salt are likewise put into the tub, and a pailful of hot
water.’--_Foot note on this passage._--‘In London, where the goodness of
bread is estimated entirely by its whiteness, it is usual with those
bakers who employ flour of an inferior quality, to add as much alum as
common salt to the dough; or, in other words, the quantity of salt added
is diminished one half, and the deficiency supplied by an equal weight
of alum. This improves the look of the bread very much, rendering it
much whiter and firmer.’”

In a passage which we shall presently quote, our author represents the
bakers of London in a conspiracy to supply the citizens with bad bread.
We may hence infer that the full allowance he assigns of 2-1/4 pounds of
alum for every 2-1/4 pounds of salt, will be adopted in converting the
sack of flour into loaves. But as a sack of flour weighs 280 pounds, and
furnishes on an average 80 quartern loaves, we have 2-1/4 pounds divided
by 80, or (15750 grains/80) = 197 grains, for the quantity present, by
this writer, in a London quartern loaf. Yet in the very same page (39th
of vol. ii.) we have the following passage: “Alum is not added by all
bakers. The writer of this article has been assured by several bakers of
respectability, both in Edinburgh and Glasgow, on whose testimony he
relies, and who made excellent bread, that they never employed any alum.
The reason for adding it given by the London bakers is, that it renders
the bread whiter, and enables them to separate readily the loaves from
each other. This addition has been alleged by medical men, and is
considered by the community at large, as injurious to the health, by
occasioning constipation. But if we consider the small quantity of this
salt added by the baker, not quite 5-1/2 grains to a quartern loaf, we
will not readily admit these allegations. Suppose an individual to eat
the seventh part of a quartern loaf a day, he would only swallow
eight-tenths of a grain of alum, or, in reality, not quite so much as
half a grain; for one half of this salt consists of water. It seems
absurd to suppose that half a grain of alum, swallowed at different
times during the course of a day, should occasion constipation.” Is it
not more absurd to state 2-1/4 pounds or 36 ounces, as the alum
adulteration of a sack of flour by the London bakers, and within a few
periods to reduce the adulteration to one ounce?

That this voluntary abstraction of 35/36 of the alum, and substitution
of superior and more expensive flour is not expected by him from the
London bakers, is sufficiently evident from the following story. It
would appear that one of his friends had invented a new yeast for
fermenting dough, by mixing a quart of beer barm with a paste made of
ten pounds of flour and two gallons of boiling water, and keeping this
mixture warm for six or eight hours.

“Yeast made in this way,” says he, “answers the purposes of the baker
much better than brewers’ yeast, because it is clearer, and free from
the hop mixture which sometimes injures the yeast of the brewer. Some
years ago the bakers of London, sensible of the superiority of this
artificial yeast, invited a company of manufacturers from Glasgow to
establish a manufactory of it in London, and promised to use no other.
About 5,000_l._ accordingly was laid out on buildings and materials, and
the manufactory was begun on a considerable scale. The ale-brewers,
finding their yeast, for which they had drawn a good price, lie heavy on
their hands, invited _all_ the journeymen bakers to their cellars, gave
them their full of ale, and promised to regale them in that manner every
day, provided they would force their masters to take all their yeast
from the ale-brewers. The journeymen accordingly declared, in a body,
that they would work no more for their masters unless they gave up
taking any more yeast from the manufactory. The masters were obliged to
comply; the new manufactory was stopped, and the inhabitants of London
were obliged to continue to eat worse bread, because it was the interest
of the ale-brewers to sell the yeast. Such is the influence of
journeymen bakers in the metropolis of England!”

This doleful diatribe seems rather extravagant; for surely beer yeast
can derive nothing noxious to a porter drinking people, from a slight
impregnation of hops; while it must form probably a more energetic
ferment than the fermented paste of the new company, which at any rate
could be prepared in six or eight hours by any baker who found it to
answer his purpose of making a pleasant-eating bread. But it is a very
serious thing for a lady or gentleman of sedentary habits, or infirm
constitution, to have their digestive process daily vitiated by damaged
flour, whitened with 197 grains of alum per quartern loaf. Acidity of
stomach, indigestion, flatulence, headaches, palpitation, costiveness,
and urinary calculi may be the probable consequences of the habitual
introduction of so much acidulous and acescent matter.

I have made many experiments upon bread, and have found the proportion
of alum very variable. Its quantity seems to be proportional to the
badness of the flour; and hence when the best flour is used, no alum
need be introduced. That alum is not necessary for giving bread its
utmost beauty, sponginess, and agreeableness of taste, is undoubted;
since the bread baked at a very extensive establishment in Glasgow, in
which about 20 tons of flour were regularly converted into loaves in the
course of a week, united every quality of appearance with an absolute
freedom from that acido-astringent drug. Six pounds of salt were used
for every sack of flour; which, from its good quality, generally
afforded 83 or 84 quartern loaves of the legal weight of four pounds
five ounces and a half each. The loaves lost nine ounces in the oven.

Every baker ought to be able to analyse his flour. He may proceed as
follows:--A ductile paste is to be made with a pound of the flour and a
sufficient quantity of water, and left at rest for an hour; then having
tied across a bowl a piece of silken sieve-stuff, a little below the
surface of the water in the bowl, the paste is to be laid upon the sieve
on a level with the water, and kneaded tenderly with the hand, so as
merely to wash the starchy particles out of it. This portion of the
flour gets immediately diffused through the water, some of the other
constituents dissolve, and the gluten alone remains upon the filter. The
water must be several times renewed till it ceases to become milky. The
last washings of the gluten are made out of the sieve.

The whole of the turbid washings are to be put into a tall conical glass
or stoneware vessel, and allowed to remain at rest, in a cool place,
till they deposit the starch. The clear supernatant liquor is then
decanted off. The deposit consists of starch, with a little gluten. It
must be washed till the water settles over it quite clear, and then it
is to be dried.

The filtered waters being evaporated, at a boiling heat, discover flocks
floating through them, which have been supposed by some to be albumen,
and by others gluten. At last, phosphate of lime precipitates. When the
residuum has assumed a syrupy consistence in the cold, it is to be mixed
with alcohol, in order to dissolve out its sugar. Cold water being added
to what remains, effects a solution of the mucilage, and leaves the
insoluble azotized matter with the phosphate of lime.

By this mode of analysis a minute portion of resin may remain in the
gluten and in the washing water; the gluten retains also a small
proportion of a fixed oil, and a volatile principle, which may be
removed by alcohol. If we wish to procure the resin alone, we must first
of all treat the flour, well dried, with alcohol.

When corn flour, poor in gluten, is to be analyzed, the dough must be
inclosed in a linen bag, kneaded with water, and washed in that state.

In analyzing barley-meal by the above process, _hordeine_, mixed with
common starch, is obtained: they may be separated by boiling water,
which dissolves the starch, and leaves the hordeine under the aspect of
saw-dust.

[Illustration: 170 171]

_Fig._ 171. is the plan of a London baker’s oven, fired with coal fuel.

_Fig._ 170. is the longitudinal section.

_a_, the body of the oven; _b_, the door; _c_, the fire-grate and
furnace; _d_, the smoke flue; _e_, the flue above the door, to carry off
the steam and hot air, when taking out the bread; _f_, recess below the
door, for receiving the dust; _g_, damper plate to shut off the steam
flue; _h_, damper plate to shut off smoke flue, after the oven has come
to its proper heat; _i_, a small iron pan over the fire-place _c_, for
heating water; _k_, ash-pit below the furnace.

[Illustration: 172]

_Fig._ 172. is the front view; the same letters refer to the same
objects in all the figures.

The flame and burnt air of the fire at _c_, sweep along the bottom of
the oven by the right hand side, are reflected from the back to the left
hand side, and thence escape by the flue _d_; (see plan _fig._ 171).
Whenever the oven has acquired the proper degree of heat, the fire is
withdrawn, the flues are closed by the damper plates, and the lumps of
fermented dough are introduced.


BRECCIA, an Italian term, used by mineralogists and architects to
designate such compound stony masses, natural or artificial, as consist
of hard rocky fragments of considerable size, united by a common cement.
When these masses are formed of small rounded pebbles, the conglomerate
is called a pudding-stone, from a fancied resemblance to plum pudding.

_Concrete_, now so much used for the foundations of large buildings, is
a factitious breccia, or pudding-stone. See CONCRETE.


BREWING. (_Brasser_, Fr.; _Brauen_, Germ.) The art of making beer, which
see.


BRICK. (_Brique_, Fr.; _Backsteine_, _ziegelsteine_, Germ.) A solid,
commonly rectangular, composed of clay, hardened by heat, and intended
for building purposes. The natural mixture of clay and sand, called
_loam_, as well as marl, which consists of lime and clay, with little or
no sand, constitutes also a good material for making bricks. The poorer
the marl is in lime, the worse adapted it is for agricultural purposes,
and the better for the brick manufacturer, being less liable to fuse in
his kiln. When a natural compound of silica and clay can be got nearly
free from lime and magnesia, it forms a kind of bricks very refractory
in the furnace, hence termed _fire-bricks_. Such a material is the
slate-clay, _schieferthon_, of our coal measures, found abundantly, and
of excellent quality, at Stourbridge, and in the neighbourhood of
Newcastle and Glasgow. The London brickmakers add to the clay about one
third of coal ashes obtained from the kitchen dust-holes; so that when
the bricks are put into the kiln, the quantity of coaly matter attached
to their surface, serves to economise fuel, and makes them less apt to
shrink in the fire; though they are less compact, and probably less
durable, than the bricks made in the coal districts of England.

The general process of brick-making consists in digging up the clay in
autumn; exposing it, during the whole winter, to the frost, and the
action of the air, turning it repeatedly, and working it with the spade;
breaking down the clay lumps in spring, throwing them into shallow pits,
to be watered and soaked for several days. The next step is to temper
the clay, which is generally done by the treading of men or oxen. In the
neighbourhood of London, however, this process is performed in a
horse-mill. The kneading of the clay is, in fact, the most laborious but
indispensable part of the whole business; and that on which, in a great
measure, the quality of the bricks depends. All the stones, particularly
the ferruginous, calcareous, and pyritous kinds, should be removed, and
the clay worked into a homogeneous paste, with as little water as
possible.

The earth, being sufficiently kneaded, is brought to the bench of the
moulder, who works the clay into a mould made of wood or iron, and
strikes off the superfluous matter. The bricks are next delivered from
the mould, and ranged on the ground; and when they have acquired
sufficient firmness to bear handling, they are dressed with a knife, and
staked or built up in long dwarf walls, thatched over, and left to dry.
An able workman will make, by hand, 5,000 bricks in a day.

The different kinds of bricks made in England are principally _place
bricks_, _gray and red stocks_, _marl facing bricks_, and _cutting
bricks_. The place bricks and stocks are used in common walling. The
marls are made in the neighbourhood of London, and used in the outside
of buildings; they are very beautiful bricks, of a fine yellow colour,
hard, and well burnt, and, in every respect, superior to the stocks. The
finest kind of marl and red bricks, called cutting bricks, are used in
the arches over windows and doors, being rubbed to a centre, and gauged
to a height.

In France attempts were long ago made to substitute animals and machines
for the treading of men’s feet in the clay-kneading pit; but it was
found that their schemes could not replace, with advantage, human
labour, where it is so cheap, particularly for separating the stones and
heterogeneous matters from the loam. The more it is worked, the denser,
more uniform, and more durable, the bricks which are made of it. A good
French workman, in a day’s labour of 12 or 13 hours, it has been said,
is able to mould from 9,000 to 10,000 bricks, 9 inches long, 4-1/2
inches broad, and 2-1/4 thick; but he must have good assistants under
him. In many brickworks near Paris, screw-presses are now used for
consolidating the bricks and paving tiles in their moulds. M. Mollerat
employed the hydraulic press for the purpose of condensing pulverized
clay, which, after baking, formed beautiful bricks; but the process was
too tedious and costly. An ingenious contrivance for moulding bricks
mechanically, is said to be employed near Washington, in America. This
machine moulds 30,000 in a day’s work of 12 hours, with the help of one
horse, yoked to a gin wheel, and the bricks are so dry when discharged
from their moulds, as to be ready for immediate burning. The machine is
described, with figures, in the _Bulletin de la Société d’Encouragement_
for 1819, p. 361. _See further on, an account of our recent patents._

Bricks, in this country, are generally baked either in a clamp or in a
kiln. The latter is the preferable method, as less waste arises, less
fuel is consumed, and the bricks are sooner burnt. The kiln is usually
13 feet long, by 10-1/2 feet wide, and about 12 feet in height. The
walls are one foot two inches thick, carried up a little out of the
perpendicular, inclining towards each other at the top. The bricks are
placed on flat arches, having holes left in them resembling
lattice-work; the kiln is then covered with pieces of tiles and bricks,
and some wood put in, to dry them with a gentle fire. This continues two
or three days before they are ready for burning, which is known by the
smoke turning from a darkish colour to transparent. The mouth or mouths
of the kiln are now dammed up with a _shinlog_, which consists of pieces
of bricks piled one upon another, and closed with wet brick earth,
leaving above it just room sufficient to receive a faggot. The faggots
are made of furze, heath, brake, fern, &c., and the kiln is supplied
with these until its arches look white, and the fire appears at the top;
upon which the fire is slackened for an hour, and the kiln allowed
gradually to cool. This heating and cooling is repeated until the bricks
be thoroughly burnt, which is generally done in 48 hours. One of these
kilns will hold about 20,000 bricks.

Clamps are also in common use. They are made of the bricks themselves,
and generally of an oblong form. The foundation is laid with _place
brick_, or the driest of those just made, and then the bricks to be
burnt are built up, tier upon tier, as high as the clamp is meant to be,
with two or three inches of breeze or cinders strewed between each layer
of bricks, and the whole covered with a thick stratum of breeze. The
fireplace is perpendicular, about three feet high, and generally placed
at the west end; and the flues are formed by gathering or arching the
bricks over, so as to leave a space between each of nearly a brick wide.
The flues run straight through the clamp, and are filled with wood,
coals, and breeze, pressed closely together. If the bricks are to be
burnt off quickly, which may be done in 20 or 30 days, according as the
weather may suit, the flues should be only at about six feet distance;
but if there be no immediate hurry, they may be placed nine feet
asunder, and the clamp left to burn off slowly.

Floating bricks are a very ancient invention: they are so light as to
swim in water; and Pliny tells us, that they were made at Marseilles; at
Colento, in Spain; and at Pittane, in Asia. This invention, however, was
completely lost, until M. Fabbroni published a discovery of a method to
imitate the floating bricks of the ancients. According to Posidonius,
these bricks are made of a kind of argillaceous earth, which was
employed to clean silver plate. But as it could not be our tripoli,
which is too heavy to float in water, M. Fabbroni tried several
experiments with mineral agaric, guhr, lac-lunæ, and fossil meal, which
last was found to be the very substance of which he was in search. This
earth is abundant in Tuscany, and is found near Casteldelpiano, in the
territories of Sienna. According to the analysis of M. Fabbroni, it
consists of 55 parts of siliceous earth, 15 of magnesia, 14 of water, 12
of alumina, 3 of lime, and 1 of iron. It exhales an argillaceous odour,
and, when sprinkled with water, throws out a light whitish smoke. It is
infusible in the fire; and, though it loses about an eighth part of its
weight, its bulk is scarcely diminished. Bricks composed of this
substance, either baked or unbaked, float in water; and a twentieth part
of clay may be added to their composition without taking away their
property of swimming. These bricks resist water, unite perfectly with
lime, are subject to no alteration from heat or cold, and the baked
differ from the unbaked only in the sonorous quality which they have
acquired from the fire. Their strength is little inferior to that of
common bricks, but much greater in proportion to their weight; for M.
Fabbroni found, that a floating brick, measuring 7 inches in length,
4-1/2 in breadth, and one inch eight lines in thickness, weighed only
14-1/4 ounces; whereas a common brick weighed 5 pounds, 6-3/4 ounces.
The use of these bricks may be very important in the construction of
powder magazines and reverberatory furnaces, as they are such bad
conductors of heat, that one end may be made red hot while the other is
held in the hand. They may also be employed for buildings that require
to be light; such as cooking-places in ships, and floating batteries,
the parapets of which would be proof against red-hot bullets.

The following plan of a furnace or kiln for burning tiles has been found
very convenient:--

[Illustration: 173 174 175]

_Fig._ 173., front view, A A, B B, the solid walls of the furnace; _a a
a_, openings to the ash-pit, and the draught hole; _b b b_, openings for
the supply of fuel, furnished with a sheet-iron door. _Fig._ 174. Plan
of the ash-pits and air channels _c c c_. The principal branch of the
ash-pit D D D, is also the opening for taking out the tiles, after
removing the grate; E the smoke flue. _Fig._ 175. Plan of the kiln seen
from above. The grates H H H. The tiles to be fired are arranged upon
the spaces _f f f f_.

[Illustration: 176]

_Fig._ 176. is the plan and section of one of the grates upon a much
larger scale than in the preceding figures.

_Mechanical brick moulding._--Messrs. Lyne and Stainford obtained in
August, 1825, a patent for a machine for making a considerable number of
bricks at one operation. It consists, in the first place, of a
cylindrical pug-mill of the kind usually employed for comminuting clay
for bricks and tiles, furnished with rotatory knives, or cutters, for
breaking the lumps and mixing the clay with the other materials of which
bricks are commonly made. Secondly, of two movable moulds, in each of
which fifteen bricks are made at once; these moulds being made to travel
to and fro in the machine for the purpose of being alternately brought
under the pug-mill to be fitted with the clay, and then removed to
situations where plungers are enabled to act upon them. Thirdly, in a
contrivance by which the plungers are made to descend, for the purpose
of compressing the material and discharging it from the mould in the
form of bricks. Fourthly, in the method of constructing and working
trucks which carry the receiving boards, and conduct the bricks away as
they are formed.

[Illustration: 177]

_Fig._ 177. exhibits the general construction of the apparatus; both
ends of which being exactly similar, little more than half of the
machine is represented. _a_ is the cylindrical pug-mill, shown partly in
section, which is supplied with the clay and other materials from a
hopper above; _b b_, are the rotatory knives or cutters, which are
attached to the vertical shaft, and being placed obliquely, press the
clay down towards the bottom of the cylinder, in the act of breaking and
mixing it as the shaft revolves. The lower part of the cylinder is open;
and immediately under it the mould is placed in which the bricks are to
be formed. These moulds run to and fro upon ledges in the side frames of
the machine; one of the moulds only can be shown by dots in the figure,
the side rail intervening: they are situated at _c c_ and are formed of
bars of iron crossing each other, and encompassed with a frame. The
mould resembles an ordinary sash window in its form, being divided into
rectangular compartments (fifteen are proposed in each) of the
dimensions of the intended bricks, but sufficiently deep to allow the
material, after being considerably pressed in the mould, to leave it,
when discharged, of the usual thickness of a common brick.

The mould being open at top and bottom, the material is allowed to pass
into it, when situated exactly under the cylinder; and the lower side of
the mould, when so placed, is to be closed by a flat board _d_,
supported by the truck _e_, which is raised by a lever and roller
beneath, running upon a plane rail with inclined ends.

The central shaft _f_, is kept in continual rotatory motion by the
revolution of the upper horizontal wheel _g_, of which it is the axis;
and this wheel may be turned by a horse yoked to a radiating arm, or by
any other means. A part of the circumference of the wheel _g_, has teeth
which are intended at certain periods of its revolution to take into a
toothed pinion, fixed upon the top of a vertical shaft _h h_. At the
lower part of this vertical shaft, there is a pulley _i_, over which a
chain is passed that is connected to the two moulds _c_, and to the
frame in which the trucks are supported; by the rotation of the vertical
shaft, the pulley winds a chain, and draws the moulds and truck frames
along.

The clay and other material having been forced down from the cylinder
into the mould, the teeth of the horizontal wheel _g_ now come into geer
with the pinion upon _h_, and turn it and the shaft and pulley _i_, by
which the chain is wound, and the mould at the right hand of the machine
brought into the situation shown in the figure; a scraper or edge-bar
under the pug-mill having levelled the upper face of the clay in the
mould, and the board _d_, supported by the truck _e_, formed the flat
under side.

The mould being brought into this position, it is now necessary to
compress the materials, which is done by the descent of the plungers _k
k_. A friction-roller _l_, pendant from the under side of the horizontal
wheel as that wheel revolves, comes in contact with an inclined plane,
at the top of the shaft of the plungers; and, as the friction-roller
passes over this inclined plane, the plungers are made to descend into
the mould, and to compress the material; the resistance of the board
beneath causing the clay to be squeezed into a compact state. When this
has been effectually accomplished, the further descent of the plungers
brings a pin _m_, against the upper end of a quadrant catch-lever _n_,
and, by depressing this quadrant, causes the balance-lever upon which
the truck is now supported to rise at that end, and to allow the truck
with the board _d_ to descend, as shown by dots; the plungers at the
same time forcing out the bricks from the moulds, whereby they are
deposited upon the board _d_; when, by drawing the truck forward out of
the machine, the board with the bricks may be removed, and replaced by
another board. The truck may then be again introduced into the machine,
ready to receive the next parcel of bricks.

By the time that the discharge of the bricks from this mould has been
effected, the other mould under the pug cylinder has become filled with
the clay, when the teeth of the horizontal wheel coming round, take into
a pinion upon the top of a vertical shaft exactly similar to that at
_h_, but at the reverse end of the machine, and cause the moulds and the
frame supporting the trucks to be slidden to the left end of the
machine; the upper surface of the mould being scraped level in its
progress, in the way already described. This movement brings the
friction-wheel _o_, up the inclined plane, and thereby raises the truck
with the board to the under side of the mould, ready to receive another
supply of clay; and the mould at the left-hand side of the machine being
now in its proper situation under the plungers, the clay becomes
compressed, and the bricks discharged from the mould in the way
described in the former instance; when this truck being drawn out, the
bricks are removed to be dried and baked, and another board is placed in
the same situation. There are boxes _p_, upon each side of the pug
cylinder containing sand, at the lower parts of which small sliders are
to be opened (by contrivances not shown in the figure) as the mould
passes under them, for the purpose of scattering sand upon the clay in
the mould to prevent its adhering to the plungers. There is also a rack
and toothed sector, with a balance weight connected to the inclined
plane at the top of the plunger-rods, for the purpose of raising the
plunger after the friction-roller has passed over it. And there is a
spring acting against the back of the quadrant-catch for the purpose of
throwing it into its former situation, after the pin of the plunger has
risen.

One of the latest, and apparently most effective machines for
brick-making, is that patented by Mr. Edward Jones of Birmingham, in
August 1835. His improvements are described under four heads; the first
applies to a machine for moulding the earth into bricks in a circular
frame-plate horizontally, containing a series of moulds or rectangular
boxes, standing radially round the circumference of the circular frame,
into which boxes successively the clay is expressed from a stationary
hopper as the frame revolves, and after being so formed, the bricks are
successively pushed out of their boxes, each by a piston, acted upon by
an inclined plane below. The second head of the specification describes
a rectangular horizontal frame, having a series of moulding boxes placed
in a straight range, which are acted upon for pressing the clay by a
corresponding range of pistons fixed in a horizontal frame, worked up
and down by rods extending from a rotatory crank shaft, the moulding
boxes being allowed to rise for the purpose of enabling the pistons to
force out the bricks when moulded, and leave them upon the bed or board
below. The third head applies particularly to the making of tiles, for
the flooring of kilns in which malt or grain is to be dried. There is in
this contrivance a rectangular mould, with pointed pieces standing up
for the purpose of producing air-holes through the tiles as they are
moulded, which is done by pressing the clay into the moulds upon the
points, and scraping off the superfluous matter at top by hand. The
fourth or last head applies to moulding chimney pots in double moulds,
which take to pieces for the purpose of withdrawing the pot when the
edges of the slabs or sides are sufficiently brought into contact.

“The drawing which accompanies the specification very imperfectly
represents some parts of the apparatus, and the description is still
more defective; but as we are acquainted with the machinery, we will
endeavour to give it an intelligible form, and quote those parts of the
specification which point the particular features of novelty proposed to
be claimed by the patentee as his invention, under the several
heads.”[13]

  [13] Mr. Newton, in his London Journal, February, 1837.

[Illustration: 178 179]

_Fig._ 178. represents, in elevation, the first-mentioned machine for
moulding bricks. The moulds are formed in the face of a circular plate
or wheel _a a_, a portion of the upper surface of which is represented
in the horizontal view, _fig._ 179. Any convenient number of these
moulds are set radially in the wheel, which is mounted upon a central
pivot, supported by the masonry _b b_. There is a rim of teeth round the
outer edge of the wheel _a a_, which take into a pinion _c_, on a shaft
connected to the first mover; and by these means the wheel _a_, with the
moulding boxes, is made to revolve horizontally, guided by arms with
anti-friction rollers, which run round a horizontal plate _a a_, fixed
upon the masonry.

A hopper _e_, filled with the brick earth shown with one of the moulding
boxes in section, is fixed above the face of the wheel in such a way,
that the earth may descend from the hopper into the several moulding
boxes as the wheel passes round under it; the earth being pressed into
the moulds, and its surface scraped off smooth by a conical roller _f_,
in the bottom of the hopper.

Through the bottom of each moulding box there is a hole for the passage
of a piston rod _g_, the upper end of which rod carries a piston with a
wooden pallet upon it, acting within the moulding box; and the lower end
of this rod has a small anti-friction roller which, as the wheel _a_
revolves, runs round upon the face of an oblique ring or inclined way _h
h_, fixed upon the masonry.

The clay is introduced into the moulding boxes from the hopper, fixed
over the lowest part of the inclined way _h_, and it will be perceived
that as the wheel revolves, the piston rods _g_, in passing up the
inclined way, will cause the pistons to force the new-moulded bricks,
with their pallet or board under them, severally up the mould, into the
situation shown at _i_, in _fig._ 178., from whence they are to be
removed by hand. Fresh pallets being then placed upon the several
pistons, they, with the moulds, will be ready for moulding fresh bricks,
when, by the rotation of the wheel _a_, they are severally brought under
the hopper, the pistons having sunk to the bottoms of their boxes, as
the piston rods passed down the other side of the inclined way _h_.

The patentee says, after having described the first head of his
invention, he would have it understood that the same may be varied
without departing from the main object of the invention; viz. that of
arranging a series of moulds when worked by means of an inclined track,
and in such manner that bricks, tiles, or other articles made of brick
earth, may be capable of being formed in a mould with pallets or boards
laid within the moulds, and constituting the bottoms thereof, the bricks
being removed from out of the moulds, with the pallets or boards under
them, as above described. “I do not, therefore, confine myself to the
precise arrangement of the machine here shown, though it is the best
with which I am acquainted for the purpose.”

[Illustration: 180 181]

The second head of the invention is another construction of apparatus
for moulding bricks, in this instance, in a rectangular frame. _Fig._
180. is a front elevation of the machine; _fig._ 181., a section of the
same taken transversely. _a a_ is the standard frame-work and bed on
which the bricks are to be moulded. Near the corners of this standard
frame-work, four vertical pillars _b b_ are erected, upon which pillars
the frame of the moulding boxes _c_, slides up and down, and also the
bar _d_, carrying the rods of the pistons _e e e_. These pistons are for
the purpose of compressing the clay in the moulding box, and therefore
must stand exactly over and correspond with the respective moulds in the
frame _c_ beneath.

The sliding frame _c_, constituting the sides and ends of the moulding
boxes, is supported at each end by an upright sliding rod _f_, which
rods pass through guides fixed to the sides of the standard frame _a a_,
and at the lower end of each there is a roller, bearing upon the levers
_g_, on each side of the machine, but seen only in _fig._ 181., which
levers, when depressed, allow the moulding boxes to descend, and rest
upon the bed or table of the machine _h h_.

In this position of the machine resting upon the bed or table, the
brick-earth is to be placed upon, and spread over, the top of the frame
_c_, by the hands of workmen, when the descent of the plunger or pistons
_e e e_, will cause the earth to be forced into the moulds, and the
bricks to be formed therein. To effect this, rotatory power is to be
applied to the toothed wheel _i_, fixed on the end of the main driving
crank shaft _k k_, which on revolving will, by means of the crank rods
_l l_, bring down the bar _a_, with the pistons or plungers _e e e_, and
compress the earth compactly into the moulds, and thereby form the
bricks.

When this has been done, the bricks are to be released from the moulds
by the moulding frame _c_ rising up from the bed, as shown in _fig._
180., the pistons still remaining depressed, and bearing upon the upper
surfaces of the bricks. The moulding frame is raised by means of cams
_m_, upon the crank shaft, which at this part of the operation are
brought under the levers _g_, for the purpose of raising the cams and
the sliding rods _f_, into the position shown in _fig._ 181.

The bricks having been thus formed and released from their moulds, they
are to be removed from the bed of the machine by pushing forward, on the
front side, fresh boards or pallets, which of course will drive the
bricks out upon the other side, whence they are to be removed by hand.

There is to be a small hole in the centre of each pallet, and also in
the bed, for the purpose of allowing any superfluous earth to be pressed
through the moulding boxes when the pistons descend. And in order to cut
off the projecting piece of clay which would be thus formed on the
bottom of the brick, a knife-edge is in some way connected to the bed of
the machine; and as the brick slides over it, the knife separates the
protuberant lump: but the particular construction of this part of the
apparatus is considered to be of little importance; and the manner of
effecting the object is not clearly stated in the specification.

The patentee proposes a variation in this construction, which he
describes in these words: “It will be evident that in place of having
the moulds to rise, they may, by suitable arrangements, be made to
descend below the bricks. In this case, in place of the boards,
stationary blocks to receive the pallets must be fixed on the bed of the
machine, and these blocks must be shaped in such a manner as to allow of
the moulds passing over them; and then it will be desirable to use the
first part of my improvements, that of having the pallets within the
moulds at the time of moulding the bricks; or in case of working with
exceedingly stiff brick-earth, the pallets may be dispensed with.” In
1835, 1,380,279,065 bricks paid duty in the United Kingdom; the revenue
from which was 405,580_l._ 6_s._ 3_d._


BRIMSTONE. (_Soufre_, Fr.; _Schwefel_, Germ.) Sulphur, which see.


BRITISH GUM. The trivial name given to starch, altered by a slight
calcination in an oven, whereby it assumes the appearance and acquires
the properties of gum, being soluble in cold water, and forming in that
state a paste well adapted to thicken the colours of the calico printer.
See STARCH.


BROMINE, one of the archæal elements, which being developed from its
combinations at the positive pole of the voltaic circuit, has been
therefore deemed to be idio-electro-positive like oxygen and chlorine.
It derives its name from its nauseous smell, Βρῶμος, _fœtor_. It occurs
in various saline springs on the continent of Europe, in those of Ashby
de la Zouche, and some others in England; in the lake Asphaltites, in
sponges, in some marine plants, in an ore of zinc, and in the cadmium of
Silesia. At ordinary temperatures it is liquid, of a dark brown colour
in mass, but of a hyacinth-red in thin layers. Its smell is rank and
disagreeable, somewhat like that of chlorine. It has a very caustic
taste. Its specific gravity is 2·966. Applied to the skin it colours it
deep yellow and corrodes it. One drop put within the bill of a bird
suffices to kill it. It combines with oxygen with feeble affinity,
forming bromic acid. Its attraction for hydrogen being far more
energetic, it forms therewith a strong acid, the hydrobromic.

Bromine dissolves very sparingly in water, but it is very soluble in
alcohol and ether. It combines with carbone, phosphorus, sulphur, and
chlorine, as well as with most of the metals. From its scarcity it has
not hitherto been applied to any purpose in the arts, but it is supposed
to possess powerful discutient effects upon scrophulous and other
glandular tumours, whence the waters containing it are prescribed as an
internal and external remedy in such forms of disease.


BRONZE. A compound metal consisting of copper and tin, to which
sometimes a little zinc and lead are added. This alloy is much harder
than copper, and was employed by the ancients to make swords, hatchets,
&c., before the method of working iron was generally understood. The art
of casting bronze statues may be traced to the most remote antiquity,
but it was first brought to a certain degree of refinement by Theodoros
and Rœcus of Samos, about 700 years before the Christian era, to whom
the invention of modelling is ascribed by Pliny. The ancients were well
aware that by alloying copper with tin, a more fusible metal was
obtained, that the process of casting was therefore rendered easier, and
that the statue was harder and more durable; and yet they frequently
made them of copper nearly pure, because they possessed no means of
determining the proportions of their alloys, and because by their mode
of managing the fire, the copper became refined in the course of
melting, as has happened to many founders in our own days. It was during
the reign of Alexander that bronze statuary received its greatest
extension, when the celebrated artist Lysippus succeeded by new
processes of moulding and melting to multiply groups of statues to such
a degree that Pliny called them the _mob of Alexander_. Soon afterwards
enormous bronze colossuses were made, to the height of towers, of which
the isle of Rhodes possessed no less than one hundred. The Roman consul
Mutianus found 3,000 bronze statues at Athens, 3,000 at Rhodes, as many
at Olympia and at Delphi, although a great number had been previously
carried off from the last town.

In forming such statues, the alloy should be capable of flowing readily
into all the parts of the mould, however minute; it should be hard, in
order to resist accidental blows, be proof against the influence of the
weather, and be of such a nature as to acquire that greenish oxidized
coat upon the surface which is so much admired in the antique bronzes,
called _patina antiqua_. The chemical composition of the bronze alloy is
a matter therefore of the first moment. The brothers Keller, celebrated
founders in the time of Louis XIV., whose _chefs d’œuvre_ are well
known, directed their attention towards this point, to which too little
importance is attached at the present day. The statue of Desaix in the
Place Dauphine, and the column in the Place Vendôme are noted specimens
of most defective workmanship from mismanagement of the alloys of which
they are composed. On analyzing separately specimens taken from the
bas-reliefs of the pedestal of this column, from the shaft, and from the
capital, it was found that the first contained only six per cent. of
alloy, and 94 of copper, the second much less, and the third only 0·21.
It was therefore obvious that the founder, unskilful in the melting of
bronze, had gone on progressively refining his alloy, by the oxidizement
of the tin, till he had exhausted the copper, and that he had then
worked up the refuse scoriæ in the upper part of the column. The cannons
which the government furnished him for casting the monument consisted
of--

  Copper                          89·360
  Tin                             10·040
  Lead                             0·102
  Silver, zinc, iron, and loss     0·498
                                 -------
                                 100·000

The moulding of the several bas-reliefs was so ill executed, that the
chiselers employed to repair the faults removed no less than 70 tons of
bronze, which was given them, besides 300,000 francs for their work. The
statues made by the Kellers at Versailles were found on chemical
analysis to consist of--

            No. 1.    No. 2.   No. 3.  The mean.
  Copper    91·30     91·68    91·22    91·40
  Tin        1·00      2·32     1·78     1·70
  Zinc       6·09      4·93     5·57     5·53
  Lead       1·61      1·07     1·43     1·37
           ------    ------   ------   ------
           100·00    100·00   100·00   100·00

The analysis of the bronze of the statue of Louis XV. was as follows:--

  Copper   82·45  Its specific gravity was 8·482.
  Zinc     10·30
  Tin       4·10
  Lead      3·15
          ------
          100·00

The alloy most proper for bronze medals which are to be afterwards
struck, is composed of from 8 to 12 parts of tin and from 92 to 88 of
copper; to which if 2 or 3 parts in the hundred of zinc be added they
will make it assume a finer bronze tint. The alloy of the Kellers is
famous for this effect. The medal should be subjected to three or four
successive stamps of the press, and be softened between each blow by
being heated and plunged into cold water.

The bronze of bells or bell metal is composed in 100 parts of copper 78,
tin 22. This alloy has a fine compact grain, is very fusible and
sonorous. The other metals sometimes added are rather prejudicial, and
merely increase the profit of the founders. Some of the English bells
consist of 80 copper, 10·1 tin, 5·6 zinc, and 4·3 lead; the latter metal
when in such large quantity is apt to cause insulated drops, hurtful to
the uniformity of the alloy.

The _tam-tams and cymbals of bronze_.--The Chinese make use of bronze
instruments forged by the hammer, which are very thin, and raised up in
the middle; they are called gongs, from the word _tshoung_ which
signifies a bell. Klaproth has shown that they contain nothing but
copper and tin; in the proportions of 78 of the former metal and 22 of
the latter. Their specific gravity is 8·815. This alloy when newly cast
is as brittle as glass, but by being plunged at a cherry-red heat into
cold water and confined between two discs of iron to keep it in shape,
it becomes tough and malleable. The cymbals consist of 80 parts copper
and 20 tin.

Bronze vessels naturally brittle may be made tenacious by the same
ingenious process, for which the world is indebted to M. Darcet. Bronze
mortars for pounding have their lips tempered in the same way. Ancient
warlike weapons of bronze were variously compounded; swords were formed
of 87-1/2 copper, and 12-1/2 tin in 100 parts; the springs of balistæ
consisted of 97 copper, and 3 tin.

_Cannon metal_ consists of about 90 or 91 copper, and 10 or 9 of tin.
From the experiments of Papacino-d’Antony, made at Turin, in 1770, it
appears that the most proper alloy for great guns is from 12 to 14
parts of tin to 100 of copper; but the Comte Lamartilliere concluded
from his experiments made at Douay, in 1786, that never less than 8 nor
more than 11 of tin should be employed in 100 parts of bronze.

_Gilt ornaments of bronze._--This kind of bronze should be easy of
fusion, and take perfectly the impression of the mould. The alloy of
copper and zinc is when fused of a pasty consistence, does not make a
sharp cast, is apt to absorb too much amalgam, is liable to crack in
cooling, and is too tough or too soft for the chaser or the turner. Were
the quantity of zinc increased to make the metal harder, it would lose
the yellow colour suitable to the gilder. A fourfold combination of
copper, zinc, tin, and lead, is preferable for making such ornamental
bronze articles; and the following proportions are probably the best, as
they unite closeness of grain with the other good qualities. Copper 82,
zinc 18, tin 3 or 1, lead 1-1/2 or 3. In the alloy which contains most
lead, the tenacity is diminished and the density is increased, which is
preferable for pieces of small dimensions. Another alloy which is said
to require for its gilding only two thirds of the ordinary quantity of
gold, has the following composition: copper, 82·257; zinc, 17·481; tin,
0·238; lead, 0·024.

The antique bronze colour is given to figures and other objects made
from these alloys by the following process:--Two drams of sal-ammoniac,
and half a dram of salt of sorrel, (binoxalate of potash,) are to be
dissolved in fourteen ounce measures (English) of colourless vinegar. A
hair pencil being dipped into this solution, and pressed gently between
the fingers, is to be rubbed equally over the clean surface of the
object slightly warmed in the sun or at a stove; and the operation is to
be repeated till the wished for shade is obtained. (See GILDING.)

The bronze founder ought to melt his metals rapidly, in order to prevent
the loss of tin, zinc, and lead, by their oxidizement. Reverberatory
furnaces have been long used for this operation; the best being of an
elliptical form. The furnaces with dome tops are employed by the bell
founders, because their alloy being more fusible, they do not require so
intense a heat; but they also would find their advantage in using the
most rapid mode of fusion. The surface of the melting metals should be
covered with small charcoal, or coke; and when the zinc is added, it
should be dextrously thrust to the bottom of the melted copper.
Immediately after stirring the melted mass so as to incorporate its
ingredients, it should be poured out into the moulds. In general the
metals most easily altered by the fire, as the tin, should be put in
last. The cooling should be as quick as possible in the moulds to
prevent the risk of the metals separating from each other in the order
of their density, as they are very apt to do. The addition of a little
iron, in the form of tin-plate, to bronze, is reckoned to be
advantageous.

One part of tin, and two parts of copper, (nearly one atom of tin and
four of copper, or more exactly 100 parts of tin, and 215 copper,) form
the ordinary speculum metal of reflecting telescopes, which is of all
the alloys the whitest, the most brilliant, the hardest, and the most
brittle. The alloy of 1 part of tin, and 10 of copper, (or nearly one
atom of the former to eighteen of the latter,) is the strongest of the
whole series.

Ornamental objects of bronze, after being cast, are commonly laid upon
red-hot coals till they take a dull red heat, and are then exposed for
some time to the air. The surface is thereby freed from any greasy
matter, some portion of the zinc is dissipated, the alloy assumes more
of a coppery hue, which prepares for the subsequent gilding. The black
tinge which it sometimes gets from the fire may be removed by washing it
with a weak acid. It may be made very clean by acting upon it with
nitric acid, of specific gravity 1·324, to which a little common salt
and soot have been added, the latter being of doubtful utility; after
which it must be well washed in water, and dried with rags or saw dust.

BRONZING, is the art of giving to objects of wood, plaster, &c. such a
surface as makes them appear as if made of bronze. The term is sometimes
extended to signify the production of a metallic appearance of any kind
upon such objects. They ought first to be smeared over smoothly with a
coat of size or oil varnish, and when nearly dry, the metallic powder
made from Dutch foil, gold leaf, mosaic gold, or precipitated copper, is
to be applied with a dusting bag, and then rubbed over the surface with
a linen pad; or the metallic powders may be mixed with the drying oil
beforehand, and then applied with a brush. Sometimes fine copper, or
brass filings, or mosaic gold, are mixed previously with some pulverized
bone ash, and then applied in either way. A mixture of these powders
with mucilage of gum arabic is used to give paper or wood a bronze
appearance. The surface must be afterwards burnished. Copper powder
precipitated by clean plates of iron, from a solution of nitrate of
copper, after being well washed and dried, has been employed in this
way, either alone or mixed with pulverized bone-ash. A finish is given
to works of this nature by a coat of spirit varnish.

A white metallic appearance is given to plaster figures by rubbing over
them an amalgam of equal parts of mercury, bismuth, and tin, and
applying a coat of varnish over it. The iron-coloured bronzing is given
by black lead or plumbago, finely pulverized and washed. Busts and
other objects made of cast iron acquire a bronze aspect by being well
cleaned and plunged in solution of sulphate of copper, whereby a thin
film of this metal is left upon the iron.

Copper acquires by a certain treatment a reddish or yellowish hue, in
consequence of a little oxide being formed upon its surface. Coins and
medals may be handsomely bronzed as follows: 2 parts of verdigris and 1
part of sal ammoniac are to be dissolved in vinegar; the solution is to
be boiled, skimmed, and diluted with water till it has only a weak
metallic taste, and upon further dilution lets fall no white
precipitate. This solution is made to boil briskly, and is poured upon
the objects to be bronzed, which are previously made quite clean,
particularly free from grease, and set in another copper pan. This pan
is to be put upon the fire, that the boiling may be renewed. The pieces
under operation must be so laid that the solution has free access to
every point of their surface. The copper hereby acquires an agreeable
reddish brown hue, without losing its lustre. But if the process be too
long continued, the coat of oxide becomes thick, and makes the objects
appear scaly and dull. Hence they must be inspected every 5 minutes, and
be taken out of the solution the moment their colour arrives at the
desired shade. If the solution be too strong, the bronzing comes off
with friction, or the copper gets covered with a white powder, which
becomes green by exposure to air, and the labour is consequently lost.
The bronzed pieces are to be washed with many repeated waters, and
carefully dried, otherwise they would infallibly turn green. To give
fresh-made bronze objects an antique appearance, three quarters of an
ounce of sal ammoniac, and a dram and a half of binoxalate of potash
(salt of sorrel) are to be dissolved in a quart of vinegar, and a soft
rag or brush moistened with this solution is to be rubbed over the clean
bright metal, till its surface becomes entirely dry by the friction.
This process must be repeated several times to produce the full effect;
and the object should be kept a little warm. Copper acquires very
readily a brown colour by rubbing it with a solution of the common liver
of sulphur, or sulphuret of potash.

The Chinese are said to bronze their copper vessels by taking 2 ounces
of verdigris, 2 ounces of cinnabar, 5 ounces of sal ammoniac and 5
ounces of alum, all in powder, making them into a paste with vinegar,
and spreading this pretty thick like a pigment on the surfaces
previously brightened. The piece is then to be held a little while over
a fire, till it becomes uniformly heated. It is next cooled, washed, and
dried; after which it is treated in the same way once and again till the
wished-for colour is obtained. An addition of sulphate of copper makes
the colour incline more to chesnut brown, and of borax more to yellow.
It is obvious that the cinnabar produces a thin coat of sulphuret of
copper upon the surface of the vessel, and might probably be used with
advantage by itself.

To give the appearance of antique bronze to modern articles, we should
dissolve 1 part of sal ammoniac, 3 parts of cream of tartar, and 6 parts
of common salt in 12 parts of hot water, and mix with the solution 8
parts of a solution of nitrate of copper of specific gravity 1·160. This
compound, when applied repeatedly in a moderately damp place to bronze,
gives it in a short time a durable green coat, which becomes by degrees
very beautiful. More salt gives it a yellowish tinge, less salt a bluish
cast. A large addition of sal ammoniac accelerates the operation of the
mordant.

BROWNING _of gun-barrels and other arms._--By this process, the surface
of several articles of iron acquires a shining brown colour. This
preparation, which protects the iron from rust, and also improves its
appearance, is chiefly employed for the barrels of fowling-pieces and
soldier’s rifles, to conceal the fire-arms from the game and the enemy.
The finest kind of browning is the Damascus, in which dark and bright
lines run through the brown ground.

This operation consists in producing a very thin uniform film of oxide
or rust upon the iron, and giving a gloss to its surface by rubbing wax
over it, or coating it with a shell-lac varnish.

Several means may be employed to produce this rust speedily and well.
The effect may be obtained by inclosing the barrels in a space filled
with the vapour of muriatic acid. Moistening their surface with dilute
muriatic or nitric acid, will answer the same purpose. But the most
common material used for browning, is the butter or chloride of
antimony, which, on account of its being subservient to this purpose,
has been called _bronzing salt_. It is mixed uniformly with olive oil,
and rubbed upon the iron slightly heated; which is afterwards exposed to
the air, till the wished-for degree of browning is produced. A little
aquafortis is rubbed on after the antimony, to quicken its operation.
The brown barrel must be then carefully cleaned, washed with water,
dried, and finally polished, either by the steel burnisher, or rubbed
with white wax, or varnished with a solution of 2 ounces of shell-lac,
and 3 drams of dragon’s blood, in 2 quarts of spirit of wine.

The following process may also be recommended: Make a solution with half
an ounce of aquafortis, half an ounce of sweet spirit of nitre, 1 ounce
of spirit of wine, 2 ounces of sulphate of copper, and 1 ounce of
tincture of iron, in so much water as will fill altogether a quart
measure. The gun barrel to be browned must first of all be filed and
polished bright, and then rubbed with unslaked lime and water to clear
away all the grease. Its two ends must now be stopped with wooden rods,
which may serve as handles, and the touch-hole must be filled with wax.
The barrel is then to be rubbed with that solution, applied to linen
rags or a sponge, till the whole surface be equally moistened; it is
allowed to stand 24 hours, and is then scrubbed with a stiff brush. The
application of the liquid and the brushing may be repeated twice or
oftener, till the iron acquires a fine brown colour. After the last
brushing, the barrel must be washed with plenty of boiling water,
containing a little potash; then washed with clean water, dried, rubbed
with polishing hard wood, and coated with shell-lac varnish, for which
purpose the barrel must be heated to the boiling point of water. It is
finally polished with a piece of hard wood.

Storch recommends to make a browning solution with 1 part of sulphate of
copper, one third of a part of sulphuric ether, and 4 parts of distilled
water.

To give the damask appearance, the barrel must be rubbed over first with
very dilute aquafortis and vinegar, mixed with a solution of blue
vitriol; washed and dried, and rubbed with a hard brush to remove any
scales of copper which may be precipitated upon it from the sulphate.

Statues, vases, bas-reliefs, and other objects made of gypsum, may be
durably bronzed, and bear exposure to the weather better than after the
ordinary oil-varnish, by the following process:--Prepare a soap from
linseed oil, boiled with caustic soda lye, to which add a solution of
common salt, and concentrate it by boiling, till it becomes somewhat
granular upon the surface. It is then thrown upon a piece of linen
cloth, and strained with moderate pressure. What passes through is to be
diluted with boiling water, and again filtered. On the other hand, 4
parts of blue vitriol and 1 part of copperas are to be dissolved
separately in hot water. This solution is to be poured slowly into the
solution of soap, as long as it occasions any precipitate. This
flocculent matter is a mixture of cupreous soap and ferruginous soap,
that is, a combination of the oxides of copper and iron with the
margaric acid of the soda soap. The copper soap is green, the iron soap
is reddish brown, and both together resemble that green rust which is
characteristic of the antique bronzes. When the precipitate is
completely separated, a fresh portion of the vitriol solution is to be
poured upon it in a copper pan, and is made to boil, in order to wash
it. After some time, the liquid part must be decanted, and replaced by
warm water for the purpose of washing the metallic soaps. They are
finally treated with cold water, pressed in a linen bag, drained and
dried. In this state the compound is ready for use in the following
way:--

Three pounds of pure linseed oil are to be boiled with twelve ounces of
finely-powdered litharge, then strained through a coarse canvass cloth,
and allowed to stand in a warm place till the soap turns clear. Fifteen
ounces of this soap-varnish, mixed with 12 ounces of the above metallic
soaps, and 5 ounces of fine white wax, are to be melted together at a
gentle heat in a porcelain basin, by means of a water bath. The mixture
must be kept for some time in a melted state, to expel any moisture
which it may contain. It must be then applied, by means of a painter’s
brush, to the surface of the gypsum previously heated to the temperature
of about 200° F. By skilful management of the heat, the colour may be
evenly and smoothly laid on without filling up the minute lineaments of
the busts. When, after remaining in the cool air for a few days, the
smell of the pigment has gone off, the surface is to be rubbed with
cotton wool, or a fine linen rag, and variegated with a few streaks of
metal powder or shell gold. Small objects may be dipped in the melted
mixture, and then exposed to the heat of a fire till they are thoroughly
penetrated and evenly coated with it.


BROWN DYE. Upon this subject some general views are given in the article
DYEING, explanatory of the nature of this colour, to which I may in the
first place refer. This dye presents a vast variety of tints, from
yellow and red to black brown, and is produced either by mixtures of
red, yellow, and blue with each other, or of yellow or red with black,
or by substantive colours, such as catechu or oxide of manganese, alone.
We shall here notice only the principal shades; leaving their
modifications to the caprice or skill of the dyer.

1. Brown from mixture of other colours.

Wool and woollen cloths must be boiled with one eighth their weight of
alum and sulpho-tartrate of iron (see this article); afterwards washed,
and winced through the madder bath, which dyes the portion of the stuff
imbued with the alum red, and that with the salt of iron black; the tint
depending upon the proportion of each, and the duration of the madder
bath.

A similar brown is produced by boiling every pound of the stuff with two
ounces of alum, and one ounce of common salt, and then dyeing it in a
bath of logwood containing either sulphotartrate, acetate, or sulphate
of iron. Or the stuff may be boiled with alum and tartar, dyed up in a
madder bath, and then run through a black bath of iron mordant and galls
or sumach. Here the black tint is added to the red till the proper hue
be hit. The brown may be produced also by adding some iron liquor to the
madder bath, after the stuff has been dyed up in it with alum and
tartar. A better brown of this kind is obtained by boiling every pound
of wool with 2 ounces of alum, dyeing it up in cochineal, then changing
the crimson thus given into brown, by turning the stuff through the bath
after acetate of iron has been added to it. Instead of the cochineal,
archil or cutbear, with a little galls or sumach, may be used.

Wool or silk may also receive a light blue ground from the indigo vat,
then be mordanted with alum, washed, and turned through a madder bath
till the wished-for brown be brought out. For the deeper shades, galls
or sumach may be added to the paler Brazil-wood, with more or less iron
mordant. Instead of the indigo vat, Saxon blue may be employed to ground
the stuff before dyeing it with madder, or 5 pounds of madder, with 1
pound of alum, a solution of one tenth of a pound of indigo in sulphuric
acid, may be used with the proper quantity of water for 20 pounds of
wool; for dark shades some iron mordant may be added. Or we may combine
a bath of cochineal or cutbear, fustic, and galls, and add to it
sulphate of iron and sulphate of indigo, blunted with a little potash.

If we boil woollen cloth with alum and tartar, then pass it through a
madder bath, and afterwards through one of weld or fustic, containing
more or less iron mordant, we obtain shades variable, according to the
proportions of the materials, from _mordoré_ and cinnamon to chesnut
brown.

After the same manner, bronze colours may be obtained from the union of
olive dyes with red. For 25 pounds of cloth, we take 4 pounds of fustic
chips, boil them for 2 hours, turn the cloth in this bath for an hour,
and drain it; then add to the bath from 4 to 6 ounces of sulphate of
iron, and 1 pound of ordinary madder, or 2 pounds of sandal wood; put
the cloth again in this compound bath, and turn it through, till the
desired shade be obtained. By changing the proportions, and adding an
iron mordant, other tints may be produced.

This mode of dyeing is suitable for silk, but with three different
baths, one of logwood, one of Brazil-wood, and one of fustic. The silk,
after being boiled with soap, is to be alumed, and then dyed up in a
bath compounded of these three decoctions, mixed in the requisite
proportions. By the addition of walnut peels, sulphate of copper, and a
little sulphate of iron, or by passing the silk through a bath of
annotto, a variety of brown shades may be had.

Or the silk may receive an annotto ground, and then be passed through a
bath of logwood or Brazil-wood. For 10 pounds of silk, 6 ounces of
annotto are to be taken, and dissolved with 18 ounces of potashes in
boiling water. The silk must be winced through this solution for 2
hours, then wrung out, dried, next alumed, passed through a bath of
Brazil-wood, and finally through a bath of logwood containing some
sulphate of iron. It is to be wrung out and dried.

Brown of different shades is imparted to cotton and linen, by
impregnating them with a mixed mordant of acetates of alumina and iron,
and then dyeing them up, either with madder alone, or with madder and
fustic. When the aluminous mordant predominates, the madder gives an
amaranth tint. For horse-chesnut brown, the cotton must be galled,
plunged into a black bath, then into a bath of sulphate of copper, next
dyed up in a decoction of fustic, wrung out, passed through a strong
madder bath, then through the sulphate of copper solution, and finished
with a soap boil. Different shades of cinnamon are obtained, when
cottons first dyed up with madder get an olive cast with iron liquor in
a fustic bath.

These cinnamon and mordoré shades are also produced by dyeing them first
in a bath of weld and verdigris, passing them through a solution of
sulphate of iron, wringing and drying them; next putting them through a
bath containing 1 pound of galls for 10 pounds of stuff, again drying,
next aluming, and maddering. They must be brightened by a boil in soap
water.

A superior brown is produced by like means upon cotton goods, which have
undergone the oiling process of the Turkey red dye. Such stuffs must be
galled, mordanted with alum (see MADDER), sulphate of iron, and acetate
of lead (equal to 2/3 of the alum); after washing and drying, dyed in a
madder bath, and cleared with a soap boil. The tint of brown varies with
the proportion of alum and sulphate of iron.

We perceive from these examples, in how many ways the browning of dyes
may be modified, upon what principles they are founded, and how we have
it in our power to turn the shade more or less towards red, black,
yellow, blue, &c.

Brown may be produced by direct dyes. The decoction of oak bark dyes
wool a fast brown of different shades, according to the concentration of
the bath. The colour is more lively with the addition of alum.

The decoction of bastard marjoram (_Origanum vulgare_) dyes cotton and
linen a reddish brown, with acetate of alumina. Wool takes from it a
dark brown.

The bark of the mangrove tree (_Rizophora mangle_) affords to wool
boiled with alum and tartar a fine red brown colour, which, with the
addition of sulphate of iron, passes into a fast chocolate.

The _Bablah_, the pods of the East Indian _Mimosa cineraria_, and the
African _Mimosa nilotica_, gives cotton a brown with acetate or sulphate
of copper.

The root of the white sea rose (_Nymphæa alba_) gives to cotton and wool
beautiful shades of brown. A mordant of sulphate of iron and zinc is
first given, and then the wool is turned through the decoction of the
root, till the wished-for shade is obtained. The cotton must be
mordanted with a mixture of the acetates of iron and zinc.

Walnut peels (_Juglans regia_), when ripe, contain a dark brown dye
stuff, which communicates a permanent colour to wool. The older the
infusion or decoction of the peels, the better dye does it make. The
stuff is dyed in the lukewarm bath, and needs no mordant, though it
becomes brighter with alum. Or this dye may be combined with the madder
or fustic bath, to give varieties of shade. For dyeing silk, this bath
should be hardly lukewarm, for fear of causing inequality of colour.

The peelings of horse-chesnuts may be used for the same purpose. With
muriate of tin they give a bronze colour, and with acetate of lead a
reddish brown.

Catechu gives cotton a permanent brown dye, as also a bronze, and
mordoré, when its solution in hot water is combined with acetate or
sulphate of copper, or when the stuff is previously mordanted with the
acetates of copper and alumina mixed, sometimes with a little iron
liquor, rinsed, dried, and dyed up, the bath being at a boiling heat.

Ferrocyanate of copper gives a yellow brown or a bronze to cotton and
silk.

The brown colour called _carmelite_ by the French is produced by one
pound of catechu to four ounces of verdigris, with five ounces of
muriate of ammonia.--The bronze (_solitaire_) is given by passing the
stuff through a solution of muriate or sulphate of manganese, with a
little tartaric acid, drying, passing through a potash lye at 4° Baumé,
brightening and fixing with solution of chloride of lime.


BRUSHES. (_Brosses_, Fr.; _Bürsten_, Germ.) Mr. T. Mason obtained a
patent in October, 1830, for an improvement in the manufacture of this
article. It consists in a firmer mode of fixing the knots or small
bundles of hair into the stock or the handle of the brush. This is done
by forming grooves in the stocks of the brushes, for the purpose of
receiving the ends of the knots of hair, instead of the holes drilled
into the wood, as in brushes of the common constructions. These grooves
are to be formed like a dovetail, or wider at the bottom than the top;
and when the ends of the knots of hair have been dipped into cement,
they are to be placed in the grooves and compressed into an oval form,
by which the ends of the hair will be pressed outwards into the recess
or wider part of the dovetailed groove, or the grooves may be formed
with threads or teeth on the sides, instead of being dovetailed; and the
cement and hairs being pressed into the teeth or threads, will cause
them to adhere firmly to the stock or handle of the brush.

[Illustration: 182 183 184]

A metal ferrule may be placed on the outside of the stock of the brush,
if necessary, and secured by pins or rivets, or in any other convenient
manner, which ferrule may also form one side of the outer groove. _Fig._
182. is a plan view of the stock of a round brush; _fig._ 183. is a
section of the same; _a a_ are the dovetailed grooves, which are turned
out of the wood; _b_ is the metal ferrule; _c c_ are knots or small
bundles of hair, to form the brush. After a number of the knots of hair
are prepared, the ends are to be dipped into proper cement, and then
placed into the grooves, when their ends are to be squeezed by a pair of
plyers, or other means, which will compress them into the oval shape, as
shown in _fig._ 184., and cause the ends of the hairs to extend outward
under the dovetailed part of the recess.

The knots of hair are to be successively placed in the grooves, and
forced up by a tool against the last knot put in, and so on, until the
grooves are filled; _fig._ 184. is a section taken through a brush with
teeth or threads of a screw formed upon the sides of the groove; into
these teeth or threads the cement and hairs will be forced by the
compression, by which means they will be held firmly in the stock of the
brush.


BUTTER. (_Beurre_, Fr.; _Butter_, Germ.) Milk contains a fatty matter of
more or less consistency, modified very much according to the nature of
the animals which afford it. This substance is butter, held suspended in
the milk by means of the caseous matter and whey, with which it is
intimately blended. Milk is a true emulsion resulting from the mixture
of these three ingredients, owing its opacity and white colour to the
diffusion through it of that butyraceous oil. When any circumstance
dissolves this union, each component becomes insulated, and manifests
its peculiar properties. Milk, even left to itself, at a temperature of
from 50° to 60° F., separates spontaneously into several products. A
layer of a fatter, more consistent, but lighter nature, floats upon its
surface, while the subjacent liquid forms a white magma, which retains
among its curdy flocks all the whey of the milk. The upper layer or
cream contains nearly the whole of the butter; but a portion remains
entangled with the curd and whey below.

It belongs to a work on husbandry or rural economy to treat fully of the
operations of the dairy; one of the principal of which is the extraction
of butter from milk.

The Tartars and French have been long in the habit of preserving butter,
by melting it with a moderate heat, whereby are coagulated the
albuminous and curdy matters remaining in it, which are very
putrescible. This fusion should be made by a heat of a water bath, about
176° F., continued for some time, to effect the more complete
purification of the butter. If in this settled liquified state it be
carefully decanted, strained through a tammy cloth, and slightly salted,
it may be kept for a long time nearly fresh, without becoming in any
degree rancid, more especially if it be put up in small jars closely
covered.


BUTTER OF CACAO. See CACAO and OILS.


BUTTON MANUFACTURE. This art is divided into several branches,
constituting so many distinct trades. Horn, leather, bone, and wood, are
the substances frequently employed for buttons, which are either plain,
or covered with silk, mohair thread, or other ornamental materials. The
most durable and ornamental buttons are made of various metals,
polished, or covered with an exceedingly thin wash, as it is termed, of
some more valuable metal, chiefly tin, silver, and gold.

Those buttons intended to be covered with silk, &c. are termed, in
general, moulds. They are small circles, perforated in the centre, and
made from those refuse chips of bone which are too small for other
purposes. These chips, which, for the large and coarser buttons, are
pieces of hard wood, are sawn into thin flakes, of an equal thickness;
from which, by a machine, the button moulds are cut out at two
operations.

The shavings, sawdust, and more minute fragments, are used by
manufacturers of cutlery and iron toys, in the operations of
case-hardening; so that not the smallest waste takes place.

Metal buttons are formed of an inferior kind of brass, pewter, and other
metallic compositions: the shanks are made of brass or iron wire, the
formation of which is a distinct trade. The buttons are made by casting
them round the shank. For this purpose the workman has a pattern of
metal, consisting of a great number of circular buttons, connected
together in one plane by very small bars from one to the next; and the
pattern contains from four to twelve dozen of buttons of the same size.
An impression from this pattern is taken in sand in the usual manner;
and shanks are pressed into the sand in the centre of each impression,
the part which is to enter the metal being left projecting above the
surface of the sand. The buttons are now cast from a mixture of brass
and tin; sometimes a small proportion of zinc is added, which is found
useful in causing the metal to flow freely into the mould, and make a
sharp casting. When the buttons are cast, they are cleaned from the sand
by brushing; they are then broken asunder, and carried to a second
workman at the lathe, who inserts the shank of a button into a chuck of
a proper figure, in which it is retained by the back centre of the lathe
being pressed against the button with a spring. The circumference is
now, by filing it as it turns round, reduced to a true circle; and the
button is instantly released by the workman’s holding back the centre,
and is replaced by another. A third workman now turns the back of the
button smooth, in a chuck lathe, and makes the projecting part round the
shank true; and a fourth renders the face of the button smooth, by
placing it in a chuck, and applying the edge of a square bar of steel
across its centre.

Gilt buttons are stamped out from copper, (having sometimes a small
alloy of zinc,) laminated in the flatting mill to the proper thickness.
The stamp is urged by a fly-press, which cuts them out at one stroke.
These circular pieces, called blanks, are annealed in a furnace to
soften them; and the maker’s name, &c. is struck on the back by a
monkey, which is a machine very similar to a pile-engine. This stamp
also renders the face very slightly convex, that the buttons may not
stick together in the gilding process. The shanks are next soldered on.
The burnishing is performed by a piece of hematites or blood-stone,
fixed into a handle, and applied to the button as it revolves by the
motion of the lathe.

A great number of the buttons, thus prepared for gilding, are put into
an earthen pan, with the proper quantity of gold to cover them[14],
amalgamated with mercury in the following manner:--The gold is put into
an iron ladle, and a small quantity of mercury added to it; the ladle is
held over the fire, till the gold and mercury are perfectly united. This
amalgam being put into the pan with the buttons, as much aquafortis,
diluted with water, as will wet them all over, is thrown in, and they
are stirred up with a brush, till the acid, by its affinity to the
copper, carries the amalgam to every part of its surface, covering it
with the appearance of silver. When this is perfected, the acid is
washed away with clean water. This process by the workman is called
quicking.

  [14] By act of parliament 5 grains of gold are allotted for the
  purpose of gilding 144 buttons, though they may be tolerably well gilt
  by half that quantity. In this last case, the thickness would be about
  the 214,000th part of an inch.

The old process in gilding buttons, called the drying off, was
exceedingly pernicious to the operator, as he inhaled the vapour of the
mercury, which is well known to be a violent poison. In order to obviate
this, the following plan of apparatus has been employed with success.
The vapour, as it rises from the pan of buttons heated by a charcoal
fire, is conducted into an oblong iron flue or gallery, gently sloped
downwards, having at its end a small vertical tube dipping into a water
cistern, for condensing the mercury, and a large vertical pipe for
promoting the draught of the products of the combustion.

Plated buttons are stamped by the fly-press, out of copper-plate,
covered on one side with silver at the flatting-mill. The copper side is
placed upwards in stamping, and the die or hole through which they are
stamped, is rather chamfered at its edge, to make the silver turn over
the edge of the button. The backs are stamped in the same manner as the
gilt buttons. The shanks are soldered on with silver solder, and heated
one by one in the flame of a lamp, with a blow-pipe urged by bellows.
The edges are now filed smooth in the lathe, care being taken not to
remove any of the silver which is turned over the edge. They are next
dipped in acid, to clean the backs, and boiled in cream of tartar and
silver, to whiten them; after which they are burnished, the backs being
first brushed clean by a brush held against them as they revolve in the
lathe. The mode of burnishing is the same as for gilt buttons.

Button shanks are made by hand from brass or iron wire, bent and cut by
the following means:--

The wire is lapped spirally round a piece of steel bar. The steel is
turned round by screwing it into the end of the spindle of a lathe, and
the wire by this means lapped close round it till it is covered. The
coil of wire thus formed is slipped off, and a wire fork or staple with
parallel legs put into it. It is now laid upon an anvil, and by a punch
the coil of wire is struck down between the two prongs of the fork, so
as to form a figure 8, a little open in the middle. The punch has an
edge which marks the middle of the 8, and the coil being cut open by a
pair of shears along this mark, divides each turn of the coil into two
perfect button shanks or eyes.

[Illustration: 185 186 187 188 189]

Mr. Holmes, of Birmingham, obtained in May, 1833, a patent for an
improved construction of buttons. _Fig._ 185. represents the outside
appearance of one of his improved shanks, as raised or formed out of the
disc of metal which is to constitute the back of the button; _fig._
186. an edge view, looking through the shank or loop; _fig._ 187. is
another edge view, looking at the raised shank or loop endways; _fig._
188. is a section taken through the shank and disc in the direction of
the dotted line A B, in _fig._ 185.; and _fig._ 189. another section
taken in the direction of the dotted line C D, in _fig._ 185. All these
figures of his improved shanks, as well as those hereinafter described,
together with the tools used to form the same, are drawn at about half
the real size, to show the parts more distinctly. It will be seen that
the shanks or loops _a a_ are formed by partially cutting and raising,
or forcing up a portion of the metal disc or back _b_, and are
compressed or formed by the action of the tools, or punches and dies, so
as to have a rounded figure on the inside of the top part of the shank,
as at _c_, the edges of the metal being turned so as to prevent them
cutting the threads by which the button is fastened to the cloth or
garment. It will be observed that, there being but one passage or way
through which the thread can be passed to sew on the button, and that
opening being rounded on all edges, will cause the threads to keep in
the centre of the shanks, the form of the shank allowing a much neater
attachment to the garment, and keeping the threads from the edges of the
metal. The ends of the shank, or portions _e e_, which rise up from the
disc or back _b_, are made nearly circular, in order to avoid presenting
any edges of the metal to the sides of the button-hole; and when the
shank is sewed on the cloth, it forms, in conjunction with the threads,
a round attachment, thereby preventing the shank from cutting or wearing
the button-hole: the threads, when the shank is properly sewed to the
garment, nearly filling up the opening through the shank, and completing
that portion of the circle which has been taken out of the shank by the
dies in forming the crescented parts of the loop. It will be therefore
understood that the intention is, that the inside edges of the shank
should be turned as much as possible away from the threads by which the
button is sewed on the cloth, and that the outside of the shank should
be formed so as to present rounded surfaces to the button-hole, and that
the thread should fill up the opening through the shank, so as to
produce a round attachment to the garment. It should here be observed,
that the backs of the buttons shown in these figures are of the shape
generally used for buttons covered with Florentine or other fabric, or
faced with plates of thin metal, and are intended to have the edges of a
disc, or what is termed a shell, forming the face, to be closed in upon
the inclined or bevelled edges of the backs. Having now described the
peculiar form of the improved shanks which he prefers, for buttons to be
covered with Florentine or other fabric, or shells of thin metal plate,
he proceeds to describe some of the different variations from the same.

[Illustration: 190 191 192 193 194 195 196]

_Fig._ 190. is a representation of a shank, the cut through the disc or
back being effected by a parallel rib on the die, and corresponding
groove in the shaping punch, instead of the semi-circular or crescented
cut shown in _fig._ 185.; _fig._ 191. is a view of another shank, the
separation of the sides of the loop being performed by straight edges in
both punch and die. He prefers finishing this shaped shank (that is,
giving it the rounded form, to prevent its cutting the threads), by
detached punches, and dies, or pincers, as will be hereinafter
described. _Fig._ 192. is a representation of one of the improved
shanks, which has merely portions, _f f_, of the back of the button
connected to its ends. This shank may be used for buttons which have a
metal shell to be closed in upon the bevelled edges of the ends, or the
shank piece may be otherwise connected to the face part of the button.
_Fig._ 193. is a representation of a shank raised out of a small disc of
metal _g g_, intended to be soldered to the disc of metal forming the
button, or it may be otherwise fixed to the back; _fig._ 194. is a
representation of another shank for the same purpose, having only
portions of metal _h h_, for soldering or otherwise attaching it to the
back of the button, as by placing a ring or annular piece over it
forming the back, which shall be confined to the face, as before
described; _fig._ 195. is a representation of a shank raised upon a dish
or bevelled piece of metal, and is intended to be used for buttons made
from pearl-shell, horn, wood, paper, or other substances. The back part
of the button has a dovetailed recess formed in it to receive the
dish-shaped back, which is pressed into the recess, the edges of the
dish being expanded in the dovetailed parts of the recess by the
ordinary means, and thereby firmly fixing it to the button, as shown in
_fig._ 196.

[Illustration: 197 198 199 200 201 202 203 204]

Having now explained the peculiar forms of his improved shanks, he
proceeds to describe the tools, or punches and dies, by which he cuts
the disc or back from out of a sheet of metal, and at the same operation
produces and forms the shank complete. _Fig._ 197. is a longitudinal
section taken through a pair of dies and punches when separated; _fig._
198. is a similar section, taken when they are put together, and in the
act of forming a shank after cutting out the disc or back of the button
from a sheet of metal; _fig._ 199. is a face view of the punch; and
_fig._ 200. is a similar representation of the counter die, with the
tools complete, _a_ is the punch or cutter, and _b_ the counter bed, by
the circular edges of which the disc of metal is cut out of the sheet;
_c_ is a die, fixed in the cutter _a_, (upon which the name of the
button-maker may be engraved). _Fig._ 201. is a face view of this die
when removed out of the punch; _d_ is the counter die to the die _c_. It
will be perceived that these dies _c_ and _d_, together with the punch
and bed, compress the disc of metal into the form required for the back
of the button; that shown in the figures, as before stated, is of the
shape used for buttons to be covered with Florentine or thin plate
metal, in a round shell closed in upon the inclined or bevelled edge of
the back; _e_ is the cutting and shaping punch of the shank, which is
fixed within the counter die; this punch cuts through the metal of the
disc, and forms the shank as the dies approach nearer together, by
raising or forcing it up into the recess or opening in the die _c_,
where it is met by the end of another shaping punch _f_, fixed in the
punch _a_, which compresses the upper part of the shank into the recess
_g_, in the end of the punch _e_, thereby giving the shank its rounded
figure, and at the same time forming the other part of the shank into
the required shape, as described at _figs._ 185. to 189. The ends of
these shaping punches fit into and over each other, as will be seen by
the detached figures of the punches designed for forming the shank first
described. _Fig._ 202. is a representation of the punches when apart and
removed out of the dies; _fig._ 203. is a longitudinal section of the
same; _fig._ 204. is another view of the punches as seen on the top. The
sharp edge of the recess _h_, in the punch _e_, comes in contact with
the cutting edges of the projecting rib _i_, of the die _c_, and thereby
cuts through so much of the metal as is required. The edge _k_ of this
die keeps the outside ends of the shank of a spherical figure, as before
explained, while the punches force up the metal, and form the elevated
loop or shank: _u u_ are holes made through the counter die _d_, for the
passage of clearing pins, which force out the shank or back piece from
the counter die when finished; the operation of which will be shown when
describing the machinery hereafter. There are adjusting screws at the
back of the punches and dies, by which they can be regulated and brought
to their proper position one to the other.

[Illustration: 205]

Although he has shown the punches which form his improved shanks, fixed
into and working in conjunction with the punch and dies which cut out
and shape the discs of metal for the back of the button, yet he does not
intend to confine himself to that mode of using them, as flat blanks or
discs for the backs of buttons may be cut out in a separate stamping
press, and afterwards shaped in the same press or in another, and then
brought under the operation of the punches which form his improved
shanks, fixed in any suitable press. This last-mentioned mode of
producing button shanks and backs he prefers when such metals are
employed as require annealing between the operations of shaping the
backs and forming the shank. _Fig._ 205. is a section taken through a
pair of dies, in which the operation only of forming the shank is to be
performed, the backs being previously shaped in another press. In this
instance the punches _e_ and _f_ are mounted in guide-pieces _m_ and
_n_, which keep them in the proper position towards each other, the die
c being mounted in the piece _n_, and acting against the face of the
guide _m_. The blanks or backs of the buttons may be fed into these dies
by hand or any other means; and after the shank is formed, the finished
back can be pushed out of the lower die by clearing rods passed through
the holes _u u_, and removed by hand, or in any convenient manner.

[Illustration: 206 207 208 209]

When his improved shanks are formed out of iron or other metal which is
too brittle to allow of the shank being forced up and finished at one
operation in the dies and punches, he prefers cutting out and shaping
the blank or back of the button first, and after annealing it, to raise
or force up the portion of metal to form the shank into the shape shown
in _fig._ 206., that is, without the edges of the metal being turned to
prevent their cutting the threads, and after again annealing it, to bend
or turn the edges into the shape shown in _fig._ 191. by means of
suitable punches in another press, or by a pair of pincers and punch as
shown in _fig._ 207., which is a side view of a small apparatus to be
used for turning the edges of the shank by hand, with a partly formed
shank seen under operation. _a_, is the upper jaw of a pair of pincers,
this jaw being fixed on to the head of the standard _b_; the under jaw
_c_, is formed by the end of the lever or handle _d_, which has its
fulcrum in the standard _b_. _e_, is a small punch, passed through a
guide hole in the head of the standard, one end projecting into the jaws
of the pincers, the other against a piece _f_, attached by a joint to
the lever _d_, and working through a slot in the head of the standard;
this piece _f_, has an inclined plane on the side next the end of the
punch, which, in its descent, projects the punch forward against the top
of the loop of the shank, (placed at _g_,) as the pincers are closed by
forcing down the lever _d_, and, in conjunction with the jaws of the
pincers, compresses the shank into the required form, as shown at _h_,
and in the enlarged _fig._ 191. A spring, _i_, acts against a pin fixed
into the punch _e_, for the purpose of bringing it back as the jaws open
after forming a shank. _Figs._ 208. and 209. represent the face and
section of the dies mentioned before, for cutting the slits in the
discs, as at _fig._ 190.

[Illustration: 210]

[Illustration: 211]

[Illustration: 212]

[Illustration: 213 214]

Having explained the peculiar forms of his improved metallic shanks for
buttons, and the tools employed in making the same, he proceeds to
describe the machinery or apparatus by which he intends to carry his
invention into effect. He proposes to take a sheet of metal, say about
30 or 40 feet long, and of the proper width and thickness; which thin
sheet is to be wound upon a roller, and placed above the machine, so
that it can be easily drawn down into the machine as required for
feeding the punches and dies. _Fig._ 210. is a plan view of a machine,
intended to work any convenient number of sets of punches and dies
placed in rows. Eleven sets of punches and dies are represented, each
set being constructed as described under _figs._ 197 to 204; _fig._ 211.
is a side view, and _fig._ 212. a longitudinal section, taken through
the machine; _figs._ 213. and 214. are transverse sections taken through
the machine between the punches and counter dies, _fig._ 213.
representing its appearance at the face of the punches, and _fig._ 214.
the opposite view of the counter dies. _a a_, are the punches; _b b_,
the counter dies; each being mounted in rows in the steel plates _c c_,
fixed upon two strong bars _d_ and _e_, by countersunk screws and nuts,
the punches and dies being retained in their proper position by the
plates, which are screwed on to the front of the steel plates, and press
against the collars of the punches and dies. The bars _d_ and _e_ are
both mounted on the guide-pins _g g_, fixed in the heads _h h_ of the
frame, which guide pins pass through the bosses on the ends of the bars.
The bar _d_ is stationary upon the guide pins, being fixed to the heads
_h h_, by nuts and screws passed through ears cast on their bosses. The
bar _e_ slides freely upon the guide pins _g g_, as it is moved
backwards and forwards by the crank _i i_, and connecting-rods _j j_, as
the crank shaft revolves. The sheet of thin iron to be operated upon is
placed, as before stated, above the machine; its end being brought down
as at _a a_, and passed between the guide rod and clearing-plate _k_,
and between the pair of feeding-rollers _l l_, which, by revolving, draw
down a further portion of the sheet of metal between the punches and
dies, after each operation of the punches.

As the counter dies advance towards the punches, they first come in
contact with the sheet of metal to be operated upon; and after having
produced the pressure which cuts out the discs, the perforations of the
sheet are pushed on to the ends of the punches by the counter dies; and
in order that the sheet may be allowed to advance, the carriage which
supports the axles of the feeding-rollers, with the guide rod and
clearing-plate, are made to slide by means of the pin _m_, which works
in a slot in the sliding-piece _n_, bearing the axis of the
feeding-roller _l l_, the slide _n_, being kept in its place on the
frame work by dovetailed guides shown in _fig._ 214.

When the counter dies have advanced near to the sheet of metal, the pin
_m_ comes in contact with that end of the slot in the piece _n_, which
is next to the punches, and forces the carriage with feed-rollers and
clearing-plate, and also the sheet of metal, onwards, as the dies are
advanced by the reaction of the cranks; and after they have cut out the
discs, and raised the shanks, the sheet of metal will remain upon the
punches; and when the bar _e_ returns, the finished backs and shanks are
forced out of the counter dies, by the clearing-pins and rods _o o_,
which project through the bar _e_, and through the holes before
mentioned in the counter dies; these clearing-pins being stationary
between the bars _p p_, mounted upon the standard _q q_, on the cross
bar of the frame, as shown in _figs._ 210., 212., 213. Immediately after
this is done, the pins _m_ come in contact with the other ends of the
slots in the pieces _n_, and draw back the feeding-rollers _l l_,
together with the clearing-plate _k_, and the sheet of metal, away from
the punches into the position represented in the figures.

At this time the feeding of the metal into the machine is effected by a
crank-pin _r_, on the end of the crank-shafts coming in contact with the
bent end of the sliding-bar _s_, supported in standards _t t_; and as
the crank-shaft revolves, this pin _r_ forces the bar _s_ forward, and
causes the tooth or pall _u_, on its reverse end, to drive the
racket-wheel _v_, one or more teeth; and as the racket-wheel _v_ is
fixed on to the end of the axle of one of the rollers _l_, it will cause
that roller to revolve; and by means of the pair of spur-pinions on the
other ends of the axles of the feeding-rollers, they will both revolve
simultaneously, and thereby draw down the sheet of metal into the
machine. It will be perceived that the standards which support the
clearing-plate and guide-bar are carried by the axles of the feeding
rollers, and partake of their sliding motion: also that the
clearing-pins _o_, are made adjustable between the bars _p_, to
correspond with the counter dies. There is an adjustable sliding stop
_x_ upon the bar _s_, which comes in contact with the back standard _t_,
and prevents the bar _s_ sliding back too far, and consequently
regulates the quantity of sheet metal to be fed into the machine by the
pall and ratchet-wheel, in order to suit different sizes of punches and
dies. In case the weight of the bar _c_, carrying the counter dies,
should wear upon its bearings, the guide pins _g g_, have small
friction-rollers _y y_, shown under the bosses of this bar, which
friction-rollers run upon adjustable beds or planes _z z_, by which
means the guide pins may be partially relieved from the weight of the
bar _c_, and the friction consequently diminished.




C.


CABLE. (_Cable_, Fr.; _Ankertau_, Germ.) A strong rope or chain,
connecting the ship with the anchor for the purpose of mooring it to the
ground. The _sheet anchor_ cable is the strongest, and is used at sea;
the _stream_ cable is more slender, being used chiefly in rivers. A
cable’s length is 120 fathoms. The greatest improvement in mooring
vessels has been the introduction of the chain cable, which, when duly
let out, affords in the weight of its long catenary curve, an elastic
tension and play to the ship under the pressure of wind. The dead strain
upon the anchor is thus greatly reduced, and the sudden pull by which
the flukes or arms are readily snapped is in a great measure obviated.
The best iron cables are chains made of links, bound and braced by rods
across their middle. Experience has taught that the ends of these links
wear out much sooner than the sides. To remedy this evil, Mr. Hawkes,
iron manufacturer, obtained a patent in July, 1828, for constructing
these anchor chains with links considerably stouter at the ends than in
the middle. With this view, he forms the short rods of iron, of which
the links are to be made, with swells or protuberances about one third
of their length from each of their ends, so that when these are welded
together, the slenderer parts are at the sides, and the thicker at the
ends of the elliptic links. Such rods as the above are formed at once by
rolling, swagging, or any other means. When the link is welded, it may
be strengthened, by a brace or stretcher fixed across the middle.

The first avowed proposal to substitute iron cables for cordage in the
sea service, was made by Mr. Slater, surgeon of the navy, who obtained a
patent for the plan in 1808, though he does not seem to have had the
means of carrying it into effect; a very general misfortune with
ingenious projectors. It was Captain Brown of the West India merchant
service who, in 1811, first employed chain cables in the vessel
Penelope, of 400 tons burden, of which he was captain. He made a voyage
in this ship from England to Martinique and Guadaloupe and home again,
in the course of four months, having anchored many times in every
variety of ground without any accident. He multiplied his trials, and
acquired certain proofs that iron might be substituted for hemp in
making cables, not only for mooring vessels, but for the standing
rigging. Since this period chain cables have been universally introduced
into all the ships of the royal navy, but the twisted links employed at
first by Brown, have been replaced by straight ones, stayed in the
middle with a cross rod, the contrivance of Mr. Brunton, which was
secured by patent in this country and in France; but the latter patent
was suffered to fall from not being acted upon within the two years
specified by law.

The first thing to be considered in the manufacture of iron cables is,
to procure a material of the best quality, and, in using it, always to
keep in view the direction of the strain, in order to oppose the maximum
strength of the iron to it. The best form of the links may be deduced
from the following investigation.

[Illustration: 215 216]

Let A B _fig._ 215. be a circular link or ring, of one inch rod iron,
the outer circumference of the ring being 15 inches, and the inner 9. If
equal opposite forces be applied to the two points of the link C D,
pulling C towards E, and D towards F, the result will be, when the
forces are sufficiently intense, that the circular form of the link will
be changed into another form with two round ends and two parallel sides,
as seen in _fig._ 216. The ratio of the exterior to the interior
periphery which was originally as 15 to 9, or 5 to 3, is no longer the
same in _fig._ 216. Hence there will be a derangement in the relative
position of the component particles, and consequently their cohesion
will be progressively impaired, and eventually destroyed. In _fig._ 215.
the segment M N of the outside periphery being equal to 3 inches, the
corresponding inside segment will be 3/5 of it, or 1-4/5 inches. If this
portion of the link, in consequence of the stretching force, comes to be
extended into a straight line, as shown in _fig._ 216., the
corresponding segments, interior and exterior, must both be reduced to
an equal length. The matter contained in the 3 inches of the outside
periphery must therefore be either compressed, that is, condensed into
1-4/5 inch, or the inside periphery, which is only 1-4/5 inch already,
must be extended to 3 inches; that is to say, the exterior condensation
and the interior expansion must take place in a reciprocal proportion.
But, in every case, it is impossible to effect this contraction of one
side of the rod, and extension of the other, without disrupture of the
link.

Let us imagine the outside periphery divided into an infinity of points,
upon each of which equal opposite forces act to straighten the
curvature: they must undoubtedly occasion the rupture of the
corresponding part of the internal periphery. This is not the sole
injury which must result; others will occur, as we shall perceive in
considering what passes in the portion of the link which surrounds C D,
_fig._ 216., whose length is 4-1/2 inches outside, and 2-1/10 inside.
The segments M P and N O, _fig._ 215., are actually reduced to
semi-circumferences, which are inside no more than half an inch, and
outside as before. There is thus contraction in the interior, with a
quicker curvature or one of shorter radius in the exterior. The
derangement of the particles takes place here, in an order inverse to
that of the preceding case, but it no less tends to diminish the
strength of that portion of the link; whence we may certainly conclude
that the circular form of cable links is an extremely faulty one.

[Illustration: 217]

Leaving matters as we have supposed in _fig._ 215., but suppose that G
is a rod introduced into the mail, hindering its two opposite points A B
from approximating. This circumstance makes a remarkable change in the
results. The link pulled as above described, must assume the
quadrilateral form shown in _fig._ 217. It offers more resistance to
deformation than before; but as it may still suffer change of shape, it
will lose strength in so doing, and cannot therefore be recommended for
the construction of cables which are to be exposed to very severe
strains.

Supposing still the link to be circular, if the ends of the stay
comprehended a larger portion of the internal periphery, so as to leave
merely the space necessary for the plan of the next link, there can be
no doubt of its opposing more effectively the change of form, and thus
rendering the chain stronger. But, notwithstanding, the circular
portions which remain between the points of application of the strain
and the stay, would tend always to be straightened, and of consequence
to be destroyed. Besides, though we could construct circular links of
sufficient strength to bear all strains, we ought still to reject them,
because they would consume more materials than links of a more suitable
form, as we shall presently see.

The effect of two opposite forces applied to the links of a chain, is,
as we have seen, to reduce to a straight line or a straight plane every
curved part which is not stayed; whence it is obvious that twisted
links, such as Brown first employed, even with a stay in their middle,
must of necessity be straightened out, because there is no resistance in
the direction opposed to the twist. A cable formed of twisted links, for
a vessel of 400 tons stretches 30 feet, when put to the trial strain,
and draws back only 10 feet. This elongation of 20 feet proceeds
evidently from the straightening of the twist in each link, which can
take place only by impairing the strength of the cable.

From the preceding remarks, it appears that the strongest links are such
as present, in their original form, straight portions between the points
of tension; whence it is clear that links with parallel sides and round
ends, would be preferable to all others, did not a good cable require to
be able to resist a lateral force, as well as one in the direction of
its length.

[Illustration: 218]

Let us suppose that by some accident the link _fig._ 216. should have
its two extremities pulled towards Y and Z, whilst an obstacle X, placed
right opposite to its middle, resisted the effort. The side of the link
which touches X, would be bent inwards; but if as in _fig._ 218., there
is a stay A G B, the two sides would be bent at the same time; the link
would notwithstanding assume a faulty shape.

[Illustration: 219]

In thus rejecting all the vicious forms, we are naturally directed to
that which deserves the preference. It is shown in _fig._ 219. This link
has a cast-iron stay with large ends, it presents in all directions a
great resistance to every change of form; for let it be pulled in the
direction _a b_, against an obstacle _c_, it is evident that the
portions _d e_ and _d f_, which are supported by the parts _g e_ and _g
f_, cannot get deformed or be broken without the whole link giving way.
As the matter composing _g e_ and _g f_ cannot be shortened, or that
which composes _d e_ and _d f_ be lengthened, these four sides will
remain necessarily in their relative positions, by virtue of the
large-ended stay _h_, whose profile is shown in _fig._ 220.

[Illustration: 220 221]

We have examined the strength of a link in every direction, except that
perpendicular to its plane. _Fig._ 221. represents the assemblage of
three links in the above predicament; but we ought to observe, that the
obstacle C, placed between the links A B, must be necessarily very
small, and could not therefore resist the pressure or impact of the two
lateral links.

_Process of manufacturing iron cables._--The implements and operations
are arranged in the following order:--

1. A reverberatory furnace (see IRON), in which a number of rods or
round bars of the best possible wrought-iron, and of proper dimensions,
are heated to bright ignition.

2. The cutting by a machine of these bars, in equal lengths, but with
opposite bevels, to allow of the requisite crossing and splicing of the
ends in the act of welding.

3. The bending of each of these pieces by a machine, so as to form the
links; the last two operations are done rapidly while the iron is
red-hot.

4. The welding of the links at small forge fires, fitted with tools for
this express purpose, and the immediate introduction of the stay, by
means of a compound lever press.

5. Proving the strength of the cables by an hydraulic press, worked by
two men turning a winch furnished with a fly wheel.

The furnace is like those used in the sheet-iron works, but somewhat
larger, and needs no particular description here.

[Illustration: 222 223]

_Figs._ 222. and 223. are a plan and elevation of the shears with which
the rods are cut into equal pieces, for forming each a link. It is moved
at Mr. Brunton’s factory by a small steam engine, but, for the sake of
simplicity, it is here represented worked by four or more labourers, as
it may be in any establishment. These must be relieved however
frequently by others, for I believe each shears’ machine is calculated
to require nearly one horse in steam power. It is portable and must be
placed in the neighbourhood of both the furnace and bending machine.

A and B are the two cast-iron limbs of the shears. The first is fixed
and the second is movable by means of a crank shaft C, driven by a heavy
fly-wheel weighing 7 or 8 cwt.

The cutting jaws G are mounted with pieces of steel which are made fast
by bolts, and may be changed at pleasure.

E, the bar of iron to be cut. It is subjected, immediately upon being
taken out of the fire, to the shears, under a determinate uniform angle,
care being taken not to let it turn round upon its axis, lest the planes
of the successive incisions should become unequal.

F is a stop which serves to determine, for the same kind of chain, the
equality of length in the link pieces.

[Illustration: 224 225 226]

_Figs._ 224, 225, 226. plan and elevations of the machine for bending
the links into an elliptic form. It is represented at the moment when a
link is getting bent upon it.

A is an elliptic mandrel of cast-iron; it is fixed upon the top of a
wooden pillar B, solidly supported in the ground. C is the jaw of the
vice, pressed by a square-headed screw against the mandrel A.

D part of the mandrel comprehended between X and Y, formed as an
inclined plane, so as to preserve an interval equal to the diameter of
the rod between the two surfaces that are to be welded together.

E rectangular slots (shears) passing through the centre of the nut of
the mandrel, in which each of the pins F may be freely slidden.

G horizontal lever of wrought-iron six feet long. It carries at H a
pulley or friction-roller of steel, whose position may be altered
according to the diameter of the links. It is obvious that as many
mandrels are required as there are sizes and shapes of links.

The piece of iron intended to form a link being cut, is carried, while
red-hot, to the bending machine, where it is seized with the jaw of the
vice C, by one of its ends, the slant of the cut being turned upwards;
this piece of iron has now the horizontal direction _m n_; on pushing
the lever G in the line of the arrow, the roller H will force _m n_ to
be applied successively in the elliptic groove of the mandrel; thus
finally the two faces that are to be welded together will be placed
right opposite each other.

The length of the small diameter of the ellipse ought to exceed by a
little the length of the stay-piece, to allow of this being readily
introduced. The difference between the points F, E is equal to the
difference of the _radii vectores_ of the ellipse. Hence it will be
always easy to find the eccentricity of the ellipse.

[Illustration: 227]

_Fig._ 227. is a lever press for squeezing the links upon their stays,
after the links are welded. This machine consists of a strong cast-iron
piece A, in the form of a square, of which one of the branches is laid
horizontally, and fixed to a solid bed by means of bolts; the other
branch, composed of two cheeks, leaving between them a space of two
inches, stands upright. These two cheeks are united at top, and on the
back of their plane by a cross piece B. C, a rectangular staple, placed
to the right and left of the cheeks through which is passed the mandrel
D, which represents and keeps the place of the following link. E, is a
press lever, 6 feet long. F, clamp and counterclamp, between which the
link is pressed at the moment when the stay is properly placed. There
are other clamps, as well as staples C, for changing with each changed
dimension of links.

The links bent, as we have seen, are carried to the forge hearth to be
welded, and to receive their stay; two operations performed at one
heating. Whenever the welding is finished, while the iron is still
red-hot, the link is placed upright between the clamps F; then a workman
introduces into the staple the mandrel D, and now applies the stay with
a pair of tongs or pincers, while another workman strikes down the lever
E forcibly upon it. This mechanical compression first of all joins
perfectly the sides of the link against the concave ends of the stay,
and afterwards the retraction of the iron on cooling increases still
more this compression.

If each link be made with the same care, the cable must be sound
throughout. It is not delivered for use however till it be proved by the
hydraulic press, at a draw-bench made on purpose. The press is an
horizontal one, having the axis of its ram in the middle line of the
draw-bench, which is about 60 feet long, and is secured to the body of
the press by strong bolts.

The portion of chain under trial, being attached at the one end to the
end of the ram of the press, and at the other to a cross-bar at the
extremity of the draw-bench, two men put the press in action, by turning
the winch which works by a triple crank three forcing pumps alternately;
the action being equalized by means of a heavy fly-wheel. As long as the
resistance does not exceed the force of two men, the whole three pumps
are kept in play. After a while one pump is thrown out of geer and next
another, only one being worked towards the conclusion. The velocity of
the ram being retarded first one third and next two thirds, gives the
men a proportional increase of mechanical power.

The strength of two average men thus applied being computed, enables us
to know at every instant the resistance opposed by the chain to the
pressure of the ram. The strain usually applied to the stronger cables
is about 500 tons.

The side beams of the draw-bench are of cast-iron, 6 inches in diameter;
the different pieces composing it are adjusted to each other end-wise by
turned joints. Props also of cast-iron support the beams two feet
asunder, and at the height of 30 inches above the ground. The space
between them is filled with an oak plank on which the trial chain is
laid.

Strength of iron-cables compared to hemp cables:--

  +---------------------+----------------------+-----------+
  |    Iron Cables.     |    Hemp Cables.      |Resistance.|
  |Diameter of Iron Rod.|Circumference of Rope.|           |
  +---------------------+----------------------+-----------+
  |     _Inches._       |     _Inches._        |  _Tons._  |
  |     0-7/8           |      9               |    12     |
  |     1               |      10              |    18     |
  |     1-1/8           |      11              |    26     |
  |     1-1/4           |      12              |    32     |
  |     1-5/16          |      13              |    35     |
  |     1-3/8           |      14 to 15        |    38     |
  |     1-1/2           |      16              |    44     |
  |     1-5/8           |      17              |    52     |
  |     1-3/4           |      18              |    60     |
  |     1-7/8           |      20              |    70     |
  |     2               |      22 to 24        |    80     |
  +---------------------+----------------------+-----------+

It would be imprudent to put hemp cables to severer strains than those
indicated in the preceding table, drawn up from Brunton’s experiments;
but the iron cables of the above sizes will support a double strain
without breaking. They ought never in common cases however to be exposed
to a greater stress. A cable destined for ships of a certain tonnage,
should not be employed in those of greater burden. Thus treated it may
be always trusted to do its duty, and will last longer than the ship to
which it belongs. A considerable part of this decided superiority which
iron cables have over hemp ones, is undoubtedly due to the admirable
form contrived by Brunton. Repeated experiments have proved that his
cables possess double the strength of the iron rods with which they are
made--a fact which demonstrates that no stronger form can be devised or
is in fact possible.

One of the most valuable qualities of iron cables is their resisting
lateral as well as longitudinal strains as explained under _figs._ 219.
and 221.

Vessels furnished with such cables have been saved by them from the most
imminent peril. The Henry, sent out with army stores during the
peninsular war, was caught on the northern coast of Spain in a furious
storm. She run for shelter into the Bay of Biscay among the rocks, where
she was exposed for three days to the hurricane. She possessed
fortunately one of Brunton’s 70 fathom chain cables, which held good all
the time, but it was found afterwards to have had the links of its lower
portion polished bright by attrition against the rocky bottom. A hemp
cable would have been speedily torn to pieces in such a predicament.

In the contracts of the Admiralty for chain cables for the British navy,
it is stipulated that “the iron shall have been manufactured in the best
manner from pig iron, smelted from iron-stone only, and selected of the
best quality for the purpose, and shall not have received in any process
whatever subsequent to the smelting, the admixture of either the cinder
or oxides produced in the manufacture of iron; and shall also have been
puddled in the best manner upon iron bottoms, and at least three times
sufficiently drawn out at three distinct welding heats, and at least
twice properly fagotted.”

The following is a table of the breaking proof of chain cables, and of
the iron for the purpose of making them, also of the proofs required by
her majesty’s navy for chains.

  +-------------+--------------+---------------+--------------------+
  |Size of Bolt.|Proof of Bolt.|Proof of Chain.|Navy Proof of Chain.|
  +-------------+--------------+---------------+--------------------+
  |  _Inches._  |_Tons._ _Cwt._|_Tons._ _Cwt._ |       _Tons._      |
  |   1/2       |   5      7   |   8     11    |        4-1/2       |
  |   5/8       |   8      7   |  13      4    |        5-1/2       |
  |   3/4       |  12      1   |  19      5    |       10-7/8       |
  |   7/8       |  16      4   |  26      5    |       13-3/4       |
  |   1         |  21      8   |  34      5    |       18           |
  |   1-1/8     |  27      2   |  48     15    |       22-3/4       |
  |   1-1/4     |  33     10   |  53     11    |       28-1/2       |
  |   1-3/8     |  40     10   |  65      0    |       34           |
  |   1-1/2     |  48      4   |  77      0    |       40-1/2       |
  |   1-5/8     |  56     11   |  90     10    |       47-1/2       |
  |   1-3/4     |  65     12   | 105      0    |       55-1/8       |
  |   1-7/8     |  75      6   | 120     10    |       63-1/4       |
  |   2         |  85     14   | 137      0    |       72           |
  |   2-1/8     |  96     15   | 155      0    |       81-1/4       |
  +-------------+--------------+---------------+--------------------+

In Brunton’s cable the matter in the link is thrown very much into one
plane; the link being of an oval form, and provided with a stay. As
there are emergencies in which the cable must be severed, this is
accomplished in those of iron by means of a bolt and sheckle (shackle),
at every fathom or two fathoms; so that by striking out this bolt or
pin, this cable is parted with more ease than a hempen one can be cut.


CACAO, BUTTER OF. See COCOA, and OILS, UNCTUOUS.


CADMIUM, is a metal discovered about the beginning of the year 1818. It
occurs chiefly in Silesia in several ores of zinc; and may be readily
recognized by means of the blowpipe; for at the first impression of the
reducing or smoky part of the flame, the ores containing cadmium stain
the charcoal all round them with a reddish yellow circle of oxide of
cadmium. The Silesian native oxide of zinc contains from 1-1/2 to 11 per
cent. of cadmium.

The cadmium may be extracted by dissolving the ore in sulphuric acid,
leaving the solution acidulous, and diluting it with water, then
transmitting through it a stream of sulphuretted hydrogen, till the
yellow precipitate ceases to fall. This powder which is sulphuret of
cadmium, is to be dissolved in concentrated muriatic acid, the excess of
which is to be expelled by evaporation; and the muriatic salt being
dissolved in water, carbonate of ammonia is to be added in excess,
whereby the cadmium separates as a carbonate, while the small portion of
adhering copper or zinc is retained in solution by the ammonia. Herapath
has shown that, in distilling zinc _per descensum_ (see ZINC), the first
portions of gaseous metal which are disengaged burn with a brown flame
and deposit the brown oxide of cadmium.

Cadmium has the colour and lustre of tin; and is susceptible of a fine
polish. Its fracture is fibrous; it crystallizes readily in regular
octahedrons, and when it suddenly solidifies, its surface gets covered
with fine mossy vegetations. It is soft, easily bent, filed, and cut,
soils like lead any surface rubbed with it. It is harder and more
tenacious than tin, and emits a creaking sound when bent, like that
metal. It is very ductile, and may be drawn out into fine wire, and
hammered into thin leaves without cracking at the edges. Its specific
gravity, after being merely melted, is 8·604; and 8·6944 after it has
been hammered. It is very fusible, melting at a heat much under redness;
indeed at a temperature little exceeding that of boiling mercury, it
boils and distils over in drops. Its vapours have no smell. It is but
slightly altered by exposure to air. When heated in the atmosphere, it
readily takes fire, and burns with a brownish yellow smoke which is
destitute of smell. In strong acids it dissolves with disengagement of
hydrogen, and forms colourless solutions. Chromate of potash causes no
precipitate in them, unless zinc or lead be present.

There is only one oxide of cadmium, the brown above-mentioned. Its
specific gravity is 8·183. It is neither fusible nor volatile at a very
high temperature. When in the state of a hydrate it is white. The oxide
of cadmium consists of 87·45 parts of metal, and 12·55 oxygen in 100
parts. Berzelius states its atomic weight to be 55·833 to hydrogen
1·000. Its sulphuret has a fine orange yellow colour, and would form a
beautiful pigment, could the metal be found in sufficient quantity for
the purposes of art. The sulphate is applied to the eyes by surgeons for
removing specks of the cornea.


CAFEINE. A chemical principle discovered in coffee, remarkable for
containing much azote. See COFFEE.


CAJEPUT OIL is obtained from the leaves of the tree called Melaleuca
Leucadendron by Linnæus, which grows upon the mountains of Amboyna, and
in other of the Molucca islands. It is procured by distillation of the
dried leaves along with water, is prepared in great quantities in the
island of Banda, and sent to Holland in copper flasks. Hence as it comes
to us, it has a green colour. It is very limpid, lighter than water, of
a strong smell resembling camphor, and pungent taste like cardamoms.
When rectified the copper remains in the retort, and the oil comes over
colourless. It is used in medicine as a stimulant. See OILS ETHEREOUS.


CALAMANCO. A sort of woollen stuff of a shining appearance, chequered in
the warp, so that the checks are seen only upon one side.


CALAMINE. A native carbonate of zinc. See ZINC.


CALCAREOUS EARTH. (_Terre calcaire_, Fr.; _Kalkerde_, Germ.) Commonly
denotes lime, in any form; but, properly speaking, it is pure lime.


CALCAREOUS SPAR. Crystallized native carbonate of lime.


CALCEDONY. A hard mineral of the siliceous family, often cut into seals.
Under it may be grouped common calcedony, heliotrope, chrysoprase,
plasma, onyx, sardonyx, and sard.


CALCHANTUM. The ancient name of native copperas or sulphate of iron.


CALCINATION, is the chemical process of subjecting metallic bodies to
heat with access of air, whereby they are converted into a pulverulent
matter, somewhat like lime in appearance, called _calx_ in Latin. The
term calcination, however, is now used when any substance whatever is
exposed to a roasting heat.


CALCIUM. The metallic basis of lime. See LIME.


CALC-SINTER. The incrustations of carbonate of lime upon the ground, or
the pendulous conical pieces called stalactites, attached to the roofs
of caverns, are so called.


CALC-TUFF. A semi-hard irregular deposit of carbonate of lime, formed
from the waters of calcareous springs.


CALCULUS. The stony-looking morbid concretion, occasionally formed in
the bladder of urine, gall-bladder, cystic duct, kidneys, and other
parts of living animals. Its examination belongs to medical chemistry.


CALENDER, (_Calandre_, Fr.; _Kalander_, Germ.) a word derived from the
Greek _kalindros_ (cylinder), is the name of a machine, consisting of
two or more cylinders, revolving so nearly in contact with each other
that cloth passed through between them is smoothed, and even glazed, by
their powerful pressure. It is employed either to finish goods for the
market, or to prepare cotton and linen webs for the calico-printer, by
rendering their surfaces level, compact, and uniform. This condensation
and polish, or _satinage_, as the French call it, differ in degree
according to the object in view, and may be arranged into three distinct
series. 1. For goods which are to receive the first impression by the
block, a very strong pressure is required; for, upon the uniformity of
the polish, the neatness and regularity of the printing, and the
correspondence of its members, depend. In many establishments the calico
is passed twice through the calender before being sent to the tables. 2.
The pieces already dyed up at the madder bath, or otherwise, and which
remain to be filled in with other colours, or _grounded-in_, as it is
technically styled, must receive a much less considerable gloss. This is
a principle every where admitted and acted upon, because the outline of
the figured design being deranged by the washing, and sometimes in
consequence of the peculiar texture of the cloth, the printer, in order
to apply his grounding blocks properly, and to fit them to the contours
of the figures already impressed, is obliged to stretch the piece
sometimes in the direction of the warp, and sometimes of the weft, which
would be impossible if they had been hard glazed by the calender. 3. The
degree of glazing given to finished goods depends upon the taste of
purchasers, and the nature of the article; but it is, in general, much
less than for the first course of block-printing.

The most complete calender probably in existence is that used by some of
the eminent calico-printers of Alsace, as contrived by M. Charles
Dollfus, and constructed by MM. Witz, Blech, and Co. 1. It passes two
pieces at once, and thus does double the work of any ordinary machine.
2. It supersedes the necessity of having a workman to fold up the goods,
as they emerge from the calender, with the aid of a self-acting folder.
3. It receives, at pleasure, the finished pieces upon a roller, instead
of laying them in folds; and, by a very simple arrangement, it hinders
the hands of the workmen from being caught by the rollers.

Calenders, in consequence of the irregular demand for foreign orders and
shipments, are worked very irregularly, being sometimes overloaded with
duty, and at others altogether unemployed. A machine which can, when
required, turn out a double quantity of goods must, therefore, be a
desirable possession. For the first course of the printers, where high
calendering is necessary, the goods are usually passed twice through
between two paper cylinders, to give that equality of surface which
could not be obtained by one passage, however strong the pressure; and
therefore the simplification of this calender will prove no economy.
Besides, in order to increase the pressure to the requisite degree, the
cylinders would need to be made bulging at their middle part, and with
such cylinders common smoothing could not be given; for the pieces would
be glazed in the central line, and rough towards the edges. For pieces
already printed in part, and requiring only to be grounded-in for other
colours, the system of double effect has fewer objections, as a single
passage through the excellent calender described under BLEACHING, page
134., is found to answer very well.

The most remarkable feature of M. Dollfus’s machine is its being managed
by a single workman. Six or eight pieces are coiled upon the
feed-roller, and they are neither pasted nor stitched together, but the
ends are merely overlapped half a yard or so. The workman is careful not
to enter the second piece till one third or one half of the first one
has passed through on the other side, to prevent his being engrossed
with two ends at a time. He must, no doubt, go sometimes to the one side
and sometimes to the other of the machine to see that no folds or
creases occur, and to be ready for supplying a fresh piece as the
preceding one has gone through. The mechanism of the folder in the
Alsace machine is truly ingenious: it performs extremely well, really
saves the attendance of an extra workman, and is worthy the attention of
manufacturers intent upon economising hand labour. The lapping-roller
works by friction, and does its duty fully better than similar machines
guided by the hand.

The numerous accidents which have happened to the hands of workmen
engaged in calenders should direct the attention towards its effective
contrivance for preventing such misfortunes. These various improvements
in the Alsace machine may be easily adapted to the ordinary calenders of
almost every construction.

The folder is a kind of cage, in the shape of an inverted pyramid, shut
on the four sides, and open at top and bottom: the top orifice is about
five inches, the bottom one an inch and a half: the front and the back,
which are about four feet broad, are made of tin-plate or smooth
pasteboard, and the two sides are made of strong sheet-iron; the whole
being bolted together by small bars of iron. Upon the sheet-iron of the
sides, iron uprights are fixed, perforated with holes, through which the
whole cage is supported freely by means of studs that enter into them.
One of the uprights is longer than the other, and bears a slot with a
small knob, which, by means of the iron piece, joins the guide to the
crank of the cylinder, and thereby communicates to the cage a seesaw
movement: at the bottom extremity of the great upright, there is a piece
of iron in the shape of an anchor, which may be raised, or lowered, or
made fast, by screws.

At the ends of this anchor are friction-rollers, which may be drawn out
or pushed back and fixed by screws: these rollers lift alternately two
levers made of wood, and fixed to a wooden shaft.

The paws are also made of wood: they serve to lay down alternately the
plies of the cloth which passes upon the cage, and is folded zigzag upon
the floor, or upon a board set below the cage: a motion imparted by the
seesaw motion of the cage itself. See STRETCHING MACHINE.

To protect the fingers of the workmen, above the small plate of the
spreading-board or bar, there is another bar, which forms with the
former an angle of about 75°: they come sufficiently near together for
the opening at the summit of the angle to allow the cloth to pass
through, but not the fingers. See _Bulletin de la Société Industrielle
de Mulhausen_, No. 18.

I shall now describe, more minutely, the structure of the powerful but
less complicated calender mechanisms employed in the British
manufactories.

[Illustration: 228 229 230]

A front elevation of a four-rollered calender (five rollers are often
introduced) for glazing goods is given in _fig._ 228. _d l_ are two
pasteboard or paper cylinders, each 20 inches in diameter, whose
structure will be presently described: _f_ is a cast-iron cylinder
turned perfectly smooth (its fellow is often placed between _e_ and
_d_): it is eight inches in diameter outside, four inches inside, with
two inches thickness of metal. _e_ is another pasteboard cylinder,
fourteen inches in diameter: the strong cast-iron frame contains the
bushes in which the journals of the rollers turn. _o p_, is one of the
pair of levers for communicating a graduated pressure according to the
quality of the goods. _Fig._ 229, 230. are end views of the same machine
to show the working geer. The wheel _s_, on the end of the upper iron
cylinder, is ten inches in diameter; that on the end of the fellow iron
cylinder below (when it is present) is thirteen inches; both are
connected by the larger carrier wheel _t_. The lower wheel _u_ is one
third larger than the upper wheel, and therefore receives from the
carrier wheel _t_, a proportionally slower motion, which it imparts to
the central pasteboard roller _e_, lying upon it, causing it to move one
third more slowly than the upper pasteboard roller. Thus a sort of
sliding motion is produced, which, by rubbing their surfaces, glazes the
goods.

The iron rollers are made hollow for the purpose of admitting either a
hot roller of iron, or steam when hot calendering is required. The
other cylinders used formerly to be made of wood, but it was liable to
many defects. The advantage of the paper roller consists in its being
devoid of any tendency to split, crack, or warp, especially when exposed
to a considerable heat from the contact and pressure of the hot iron
rollers. The paper, moreover, takes a vastly finer polish, and, being of
an elastic nature, presses into every pore of the cloth, and smooths its
surface more effectually than any wooden cylinder, however truly turned,
could possibly do.

The paper cylinder is constructed as follows:--The axis of the cylinder
is a strong square bar of the best wrought iron, cut to the proper
length. Upon this bar a strong round plate of cast iron is first put,
somewhat less in diameter than the cylinder when finished. A quantity of
thick stout pasteboard is then procured, and cut into round pieces an
inch larger in diameter than the iron plate. In the centre of the
plates, and of every piece of the pasteboard, a square hole must be cut
to receive the axis; and, the circle being divided into six equal parts,
a hole must also be cut at each of the divisions, an inch or two within
the rim. These pieces of pasteboard being successively put upon the
axis, a long bolt of malleable iron, with a head at one end, and screwed
at the other, is also introduced through each of the holes near the rim;
and this is continued until a sufficient number of pasteboards are thus
placed to form a cylinder of the length required, proper allowance being
made for the compression which the pasteboard is afterwards to undergo.
Another round plate is then applied, and, nuts being put upon the
screws, the whole are screwed tight, and a cylinder formed. This
cylinder is now to be placed in a stove, exposed to a strong heat, and
must be kept there for at least several days; and, as the pasteboard
shrinks by exposure to the heat, the screws must be frequently tightened
until the whole mass has been compressed as much as possible. When the
cylinder is thus brought to a sufficient degree of density it is removed
from the stove; and, when allowed to cool, the pasteboard forms a
substance almost inconceivably dense and hard. Nothing now remains but
to turn the cylinder; and this is an operation of no slight labour and
patience. The motion in turning must be slow, not exceeding about forty
revolutions in a minute; the substance being now so hard and tough that
tools of a very small size must be used to cut, or rather scrape it,
until it is true. Three men are generally employed for the turning, even
when the motion of the cylinder is effected by mechanical power, two
being necessary to sharpen tools, for the third who turns, as quickly as
he blunts them.

Let us suppose it to be a five-rollered machine: when a person stands in
front of the calender, the cloth coming from behind above the uppermost
cylinder 1, passes between 1 and 2: proceeding behind 2, it again comes
to the front between 2 and 3: between 3 and 4 it is once more carried
behind, and, lastly, brought in front between 4 and 5, where it is
received, and smoothly folded on a clean board, or in a box, by a person
placed there for the purpose. In folding the cloth at this time, care
must be taken that it may be loosely done, so that no mark may appear
until it be again folded in the precise length and form into which the
piece is to be made up. The folding may be done either by two persons or
by one, with the aid of two sharp polished spikes placed at a proper
distance, to ascertain the length of the fold, and to make the whole
equal. When folded into lengths, it is again folded across upon a smooth
clean table, according to the shape intended, which varies with the
different kinds of goods, or the particular market for which the goods
are designed.

When the pieces have received the proper fold, the last operation
previous to packing them is the pressing. This is commonly performed by
placing a certain number of pieces, divided by thin smooth boards of
wood, in a common screw press, similar to those used by printers for
taking out the impression left by the types in the printing-press.
Besides the wooden boards, a piece of glazed pasteboard is placed above
and below every piece of cloth, that the outer folds may be as smooth
and glossy as possible. The operation of the common screw press being
found tedious and laborious, the hydraulic press is now in all well
mounted establishments had recourse to. See HYDRAULIC PRESS.

No improvements that have taken place in calendering can exceed the
power and facility of the water press: one of these presses may be
worked by two men, who can with great ease produce a pressure of 400
tons; but, in considerable establishments, the presses are worked by
power. See BANDANNA.

The appearance and finish of the goods, in consequence of such an
immense weight acting on them, are materially improved.

The press is also used for the purpose of packing; whereby the bale is
rendered much more compact than formerly. It is commonly roped, &c.,
while in this compressed state; the dimensions, are therefore, greatly
diminished from what they would otherwise be by any other method. For
instance, the same quantity of goods packed in a bale are from one third
to one half less bulky than if they were packed in a box with the utmost
force of the hands.

For lawns and muslins of a light texture, the operation of smoothing
requires a different process in some respects than close heavy fabrics.
They only require to be slightly smoothed to remove any marks which they
may have received at the bleaching; and, as their beauty depends rather
on their transparency than their closeness, the more the cylindrical
form of the yarn is preserved the better. They are therefore put through
a small machine, consisting of three rollers or cylinders; and, as the
power required to move this is small, the person who attends it
generally drives it by a small winch; or the same effect may be produced
by passing the muslins between only two or three rollers of the above
calender, lightly loaded.

In the thick fabrics of cloth, including those kinds which are used for
many parts of household furniture, as also those for female dress, the
operation of glazing is used both to add to the original beauty of the
cloth, and to render it more impervious to dust or smoke. The glazing
operation is performed entirely by the friction of any smooth substance
upon the cloth; and, to render the gloss brighter, a small quantity of
bleached wax is previously rubbed over the surface. The operation of
glazing by the common plan is very laborious, but the apparatus is of
the most simple kind. A table is mounted with a thick stout cover of
level and well-smoothed wood, forming an inclined plane; that side where
the operator stands at work being the lowest. The table is generally
placed near a wall, both for convenience in suspending the glazing
apparatus, and for the sake of light. A long piece of wood is suspended
in a groove formed between two longitudinal beams, placed parallel to
the wall, and fixed to it. The groove resembles exactly the aperture
between the shears of a common turning lathe. The lever, of which the
groove may be supposed to be the centre or fulcrum, is faced at the
bottom with a semi-cylindrical piece of finely polished flint, which
gives the friction to the cloth stretched upon the table below. Above
the flint are two cross handles, of which the operator lays hold, and
moves them backward and forward with his hands, keeping the flint
pressing slightly upon the cloth. When he has glazed a portion equal to
the breadth of the flint, he moves his lever between the shears
sidewise, and glazes a fresh part: thus he proceeds from one side or
selvage of the cloth to the other: and when all which is upon the table
is sufficiently glazed, he draws it over, and exposes a new portion to
the same operation. To preserve the cloth at a proper tension, it may be
wound smoothly upon a roller or beam, which being set so as to revolve
upon its own axis behind the table, another roller to receive the cloth
may be placed before, both being secured by a catch, acting in a ratchet
wheel. Of late years, however, a great part of the labour employed in
glazing cloth has been saved, as the common four or five bowl calender
has been altered to fit this purpose by direct pressure.

As a matter of accommodation, the different processes of packing,
cording of boxes, sheeting of trunks, and, in general, all the
arrangements preparatory to shipments, and also the intimations and
surveys necessary for obtaining drawbacks, debentures, or bounties,
according to the excise laws, are generally conducted at the calender
houses where goods are finished. These operations sufficiently account
for the general meaning attached to the word.


CALICO-PRINTING (_Impression d’Indiennes_, Fr.; _Zeugdruckerei_, Germ.)
is the art of impressing cotton cloth with topical dyes of more or less
permanence. Of late years, silk and woollen fabrics have been made the
subjects of a similar style of dyeing. Linens were formerly stained with
various coloured designs, but since the modern improvements in the
manufacture of cotton cloth they are seldom printed, as they are both
dearer, and produce less beautiful work, because flax possesses less
affinity than cotton for colouring matters.

This art is of very ancient date in India, and takes its English name
from Calicut, a district where it has been practised with great success
from time immemorial. The Egyptians, also, appear from Pliny’s testimony
to have practised at a remote era some of the most refined processes of
topical dyeing. “Robes and white veils,” says he, “are painted in Egypt
in a wonderful way. They are first imbued, not with dyes, but with
dye-absorbing drugs, by which, though they seem to be unaltered, yet,
when immersed for a little while in a cauldron of the boiling
dye-liquor, they are found to become painted. Yet, as there is only one
colour in the cauldron, it is marvellous to see many colours imparted to
the robe, in consequence of the influence of the excipient drug. Nor can
the dye be washed out. A cauldron, which would of itself merely confuse
the colours of cloths previously dyed, is thus made to impart several
pigments from a single dye-stuff, _painting as it boils_.” The last
expression _pingitque dum coquit_, is perfectly graphic and descriptive
of calico-printing.

The cotton chintz counterpanes of great size, called _pallampoors_,
which have been manufactured in Madras from the earliest ages, have in
like manner peculiar dye-absorbing drugs applied to them with the
pencil, as also wax, to protect certain parts of the surface from the
action of the dye, and are afterwards immersed in a staining liquor,
which, when wax is applied, is usually the cold indigo-vat, but without
the wax is a hot liquor similar to the Egyptian. M. Koechlin Roder, of
Mulhouse, brought home lately from India a rich collection of cloths in
this state of preparation, which I saw in the cabinet of the _Société
Industrielle_ of that interesting emporium of calico-printing. The
native implements for applying the wax and colouring bases are placed
alongside of the cloths, and form a curious picture of primeval art.
There is among other samples an ancient _pallampoor_, five French yards
long, and two and a half broad, said to be the labour of Hindoo
princesses, which must have taken a lifetime to execute. The printing
machinery of great Britain has begun to supersede, for these styles of
work, the cheapest hand labour of India.

Calico-printing has been for several hundred years practised by the
oriental methods in Asia Minor and the Levant, but it was unknown as an
English art till 1696, when a small print-ground was formed upon the
banks of the Thames, near Richmond, by a Frenchman; probably a refugee
from his own country, in consequence of the revocation of the edict of
Nantes. Some time afterwards, a considerable printing work was
established at Bromley Hall, in Essex, and several others sprung up
successively in Surrey, to supply the London shops with chintzes, their
import from India having been prohibited by act of parliament in 1700.
The silk and woollen weavers, indeed, had all along manifested the
keenest hostility to the use of printed calicoes, whether brought from
the East or made at home. In the year 1680 they mobbed the India House
in revenge for some large importations then made of the chintzes of
Malabar. They next induced the government, by incessant clamours, to
exclude altogether the beautiful robes of Calicut from the British
market. But the printed goods, imported by the English and Dutch East
India companies, found their way into this country, in spite of the
excessive penalties annexed to smuggling, and raised a new alarm among
the manufacturing population of Spitalfields. The sapient legislators of
that day, intimidated, as would appear, by the East London mobs, enacted
in 1720 an absurd sumptuary law, prohibiting the _wearing of all printed
calicoes whatsoever, either of foreign or domestic origin_. This
disgraceful enactment, worthy of the meridian of Cairo or Algiers,
proved not only a death blow to rising industry in this ingenious
department of the arts, but prevented the British ladies from attiring
themselves in the becoming drapery of Hindostan. After an oppressive
operation of ten years, this act was repealed by a partially enlightened
set of senators, who were then pleased to permit what they called
British calicoes, if made of linen warp, with merely weft of the _hated_
cotton, to be printed and worn, upon paying a duty of no less than
sixpence the square yard. Under this burden, English calico-printing
could not be expected to make a rapid progress. Accordingly, even so
lately as the year 1750, no more than 50,000 pieces of mixed stuff were
printed in Great Britain, and that chiefly in the neighbourhood of
London; whereas a single manufacturer, Mr. Coates of Manchester,
now-a-days will turn off nearly twenty times that quantity, and there
are very many others who manufacture several hundred thousand pieces per
annum. It was not till about 1766 that this art migrated into
Lancashire, where it has since taken such extraordinary development; but
it was only after 1774 that it began to be founded upon right
principles, in consequence of the repeal of that part of the act of 1730
which required the warp to be made of linen yarn. Henceforth the
printer, though still saddled with a heavy duty of 3_d._ the square
yard, was allowed to apply his colours to a homogeneous web, instead of
the mixed fabric of linen and cotton substances, which differ in their
affinities for dyes.

France pursued for some time a similar false policy with regard to
calico-printing, but she emerged sooner from the mists of manufacturing
monopoly than England. Her avowed motive was to cherish the manufacture
of flax, a native product, instead of that of cotton, a raw material,
for which prejudice urged that money had to be exported. Her intelligent
statesmen of that day, fully seventy years ago, replied, that the money
expended in the purchase of cotton was the produce of French industry,
beneficially employed, and they therefore took immediate measures to put
the cotton fabrics upon a footing of equality. Meanwhile the popular
prejudices became irritated to such a degree, by the project of
permitting the free manufacture and sale of printed cottons, that every
French town possessed of a chamber of commerce made the strongest
remonstrances against it. The Rouen deputies declared to the government,
“that the intended measure would throw its inhabitants into despair, and
make a desert of the surrounding country;” those of Lyons said, “the
news had spread terror through all its work-shops:” Tours “foresaw a
commotion likely to convulse the body of the state:” Amiens said, “that
the new law would be the grave of the manufacturing industry of France;”
and Paris declared that “her merchants came forward to bathe the throne
with their tears upon that inauspicious occasion.”

The government persisted in carrying its truly enlightened principles
into effect, and with so manifest advantage to the nation, as to warrant
the inspector-general of manufactures to make, soon afterwards, the
following appeal to those prejudiced bodies:--“Will any of you now deny
that the fabrication of printed cottons has occasioned a vast extension
of the industry of France, by giving profitable employment to a great
many hands in spinning, weaving, bleaching, and printing the colours?
Look only at the dyeing department, and say whether it has not done more
good to France in a few years than many of your other manufactures have
in a century?”

The despair of Rouen has been replaced by the most signal prosperity in
the cotton trade, and especially in printed calicoes, for the
manufacture of which it possesses 70 different establishments, producing
upwards of a million of pieces of greater average size and price than
the English. In the district of the Lower Seine, round that town, there
are 500 cotton factories of different kinds, which give employment to
118 thousand operatives of all orders, and thus procure a comfortable
livelihood to probably not less than half a million of people.

The repeal, in 1831, of the consolidated duty of 3-1/2_d._ per square
yard upon printed calicoes in Great Britain is one of the most judicious
acts of modern legislation. By the improvements in calico-printing, due
to the modern discoveries and inventions in chemistry and mechanics, the
trade had become so vast as to yield in 1830 a revenue of 2,280,000_l._
levied upon 8,596,000 of pieces, of which, however, about three fourths
were exported, with a drawback of 1,579,000_l._ 2,281,512 pieces were
consumed in that year at home. When the expenses of collection were
deducted, only 350,000_l._ found their way into the exchequer, for which
pitiful sum thousands of frauds and obstructions were committed against
the honest manufacturer. This reduction of duty enables the consumer to
get this extensive article of clothing from 50 to 80 per cent. cheaper
than before, and thus places a becoming dress within the reach of
thousands of handsome females in the humbler ranks of life. Printed
goods, which in 1795 were sold for two shillings and three-pence the
yard, may be bought at present for eight-pence. In fact a woman may now
purchase the materials of a pretty gown for two shillings. The repeal of
the tax has been no less beneficial to the fair dealers, by putting an
end to the contraband trade, formerly pursued to an extent equally
injurious to them and the revenue. It has, moreover, emancipated a
manufacture, eminently dependent upon taste, science, and dexterity,
from the venal curiosity of petty excisemen, by whom private
improvements, of great value to the inventor, were in perpetual jeopardy
of being pirated and sold to any sordid rival. The manufacturer has now
become a free agent, a master of his time, his workmen, and his
apparatus; and can print at whatever hour he may receive an order;
whereas he was formerly obliged to wait the convenience of the excise
officer, whose province it was to measure and stamp the cloth before it
could be packed,--an operation fraught with no little annoyance and
delay. Under the patronage of parliament, it was easy for needy
adventurers to buy printed calicoes, because they could raise such a sum
by drawbacks upon the export of one lot as would go far to pay for
another, and thus carry on a fraudulent system of credit, which sooner
or later merged in a disastrous bankruptcy. Meanwhile the goods thus
obtained were pushed off to some foreign markets, for which they were,
possibly, not suited, or where they produced, by their forced sales a
depreciation of all similar merchandize, ruinous to them and who meant
to pay for his wares.

The principles of calico-printing have been very profoundly studied by
many of the French manufacturers, who generally keep a chemist, who has
been educated in the Parisian schools of science, constantly at work,
making experiments upon colours in a well-mounted laboratory. In that
belonging to M. Daniel Kœchlin, of Mulhausen, there are upwards of 3000
labelled phials, filled with chemical reagents, and specimens
subservient to dyeing. The great disadvantage under which the French
printers labour is the higher price they pay for cotton fabrics, above
that paid by the English printers. It is this circumstance alone which
prevents them from becoming very formidable rivals to us in the markets
of the world. M. Barbet, deputy and mayor of Rouen, in his replies to
the ministerial commission of inquiry, rates the disadvantage proceeding
from that cause at 2 francs per piece, or about 5 per cent. in value. In
the annual report of the _Société Industrielle_ of Mulhausen, made in
December, 1833, the number of pieces printed that year in Alsace is
rated at 720,000, to which if we add 1,000,000 for the produce of the
department of the Lower Seine, and 280,000 for that of St. Quentin,
Lille, and the rest of France, we shall have for the total amount of
this manufacture 2,000,000 of pieces, equivalent to nearly 2,400,000
pieces English; for the French piece usually measures 33-1/2 aunes, = 41
yards nearly; and it is also considerably broader than the English
pieces upon an average. It is therefore probable that the home
consumption of France in printed goods is equal in quantity, and
superior in value, to that of England. With regard to the comparative
skill of the workmen in the two countries, M. Nicholas Kœchlin, deputy
of the Upper Rhine, says, that one of his foremen, who worked for a year
in a print-field in Lancashire, found little or no difference between
them in that respect. The English wages are considerably higher than the
French. The machines for multiplying production, which for some time
gave us a decided advantage, are now getting into very general use among
our neighbours. In my recent visit to Mulhausen, Rouen, and their
environs, I had an opportunity of seeing many printing establishments
mounted with all the resources of the most refined mechanisms.

The calico-printing of this country still labours under the burden of
considerable taxes upon madder and gallipoli oil, which have
counteracted the prosperity of our Turkey red styles of work, and caused
them to nourish at Elberfeld, and some other places on the continent,
whither a good deal of the English yarns are sent to be dyed, then
brought back, and manufactured into ginghams, checks, &c., or forwarded
directly thence to our Russian customers. This fact places our fiscal
laws in the same odious light as the facility of pirating printer’s
patterns with impunity does our chancery laws.

Before cloth can receive good figured impressions its surface must be
freed from fibrous down by SINGEING, and be rendered smooth by the
CALENDER. See these articles. They are next bleached, with the exception
of those destined for Turkey red. See BLEACHING and MADDER. After they
are bleached, dried, singed, and calendered, they are lapped round in
great lengths of several pieces, stitched endwise together, by means of
an apparatus called, in Manchester, a _candroy_, which bears on its
front edge a rounded iron bar, transversely grooved to the right and
left from the centre, so as to spread out the web as it is drawn over it
by the rotation of the lapping roller. See a figure of this bar
subservient to the cylinder printing-machine.

Four different methods are in use for imprinting figures upon calicoes:
the first is by small wooden blocks, on whose face the design is cut,
which are worked by hand; the second is by larger wood-cut blocks,
placed in either two or three planes, standing at right angles to each
other, called a Perrotine, from the name of its inventor; the third is
by flat copper plates, a method now almost obsolete; and the fourth is
by a system of copper cylinders, mounted in a frame of great elegance,
but no little complexity, by which two, three, four, or even five
colours may be printed on in rapid succession by the mere rotation of
the machine driven by the agency of steam or water. The productive
powers of this printing automaton are very great, amounting for some
styles to a piece in the minute, or a mile of cloth in the hour. The
fifth colour is commonly communicated by means of what is called a
surface cylinder, covered with wooden figures in bas-relief, which, by
rotation, are applied to a plane of cloth imbued with the thickened
mordants.

The hand blocks are made of sycamore or pear-tree wood, or of deal faced
with these woods, and are from two to three inches thick, nine or ten
inches long, and five broad, with a strong box handle on the back for
seizing them by. The face of the block is either carved in relief into
the desired design, like an ordinary wood-cut, or the figure is formed
by the insertion edgewise into the wood of narrow slips of flattened
copper wire. These tiny fillets, being filed level on the one edge, are
cut or bent into the proper shape, and forced into the wood by the taps
of a hammer at the traced lines of the configuration. Their upper
surfaces are now filed flat, and polished into one horizontal plane, for
the sake of equality of impression. As the slips are of equal thickness
in their whole depth, from having been made by running the wire through
between the steel cylinders of a flatting mill, the lines of the figure,
however much they get worn by use, are always equally broad as at first;
an advantage which does not belong to wood-cutting. The interstices
between the ridges thus formed are filled up with felt-stuff. Sometimes
a delicate part of the design is made by the wood-cutter, and the rest
by the insertion of copper slips.

The colouring matter, properly thickened, is spread with a flat brush,
by a child, upon fine woollen cloth, stretched in a frame over the wax
cloth head of a wooden drum or sieve, which floats inverted in a tubful
of old paste, to give it elastic buoyancy. The inverted sieve drum
should fit the paste tub pretty closely. The printer presses the face of
the block on the drum head, so as to take up the requisite quantity of
colour, applies it to the surface of the calico, extended upon a flat
table covered with a blanket, and then strikes the back of the block
with a wooden mallet, in order to transfer the impression fully to the
cloth. This is a delicate operation, requiring equal dexterity and
diligence. To print a piece of cloth 28 yards long, and 30 inches broad,
no less than 672 applications of a block, 9 inches long and 5 inches
broad, are requisite for each colour; so that if there are 3 colours, or
3 hands, as the French term it, no less than 2016 applications will be
necessary. The blocks have pin-points fixed into their corners, by means
of which they are adjusted to their positions upon the cloth, so as to
join the different parts of the design with precision. Each printer has
a colour-tub placed within reach of his right hand; and for every
different colour he must have a separate sieve. Many manufacturers cause
their blocks to be made of three layers of wood, two of them being deal
with the grain crossed to prevent warping, and the third sycamore for
engraving.

[Illustration: 231 232]

The printing shop is an oblong apartment, lighted with numerous windows
at each side, and having a solid table opposite to each window. The
table B, _fig._ 231. is formed of a strong plank of well-seasoned hard
wood, mahogany, or marble, with a surface truly plane. Its length is
about 6 feet, its breadth 2 feet, and its thickness 3, 4, or 5 inches.
It stands on strong feet, with its top about 36 inches above the floor.
At one of its ends there are two brackets C for supporting the axles of
the roller E, which carries the white calico to be printed. The hanging
rollers E are laid across joists fixed near the roof of the apartment
above the printing shop, the ceiling and floor between them being open
bar work, at least in the middle of the room. Their use is to facilitate
the exposure, and, consequently, the drying of the printed pieces, and
to prevent one figure being daubed by another. Should they come to be
all filled, the remainder of the goods must be folded lightly upon the
stool D.

The printer stretches a length of the piece upon his table A B, taking
care to place the selvage towards himself, and one inch from the edge.
He presents the block towards the end, to determine the width of its
impression, and marks this line A B, by means of his square and tracing
point. The spreader now besmears the cloth with the colour, at the
commencement, upon both sides of the sieve head; because, if not
uniformly applied, the block will take it up unequally. The printer
seizes the block in his right hand, and daubs it twice in different
directions upon the sieve cloth, then he transfers it to the calico in
the line A B, as indicated by the four points _a b c d_, corresponding
to the four pins in the corners of the block. Having done so, he takes
another daub of the colour, and makes the points _a b_ fall on _c d_, so
as to have at the second stamp _a´ b´_, covering _a b_ and _c´ d´_; and
so on, through the rest, as denoted by the accented letters. When one
table length is finished, he draws the cloth along, so as to bring a new
length in its place.

The grounding in, or re-entering (_rentrage_), of the other colours is
the next process. The blocks used for this purpose are furnished with
pin-points, so adjusted that, when they are made to coincide with the
pin-points of the former block, the design will be correct; that is to
say, the new colour will be applied in its due place upon the flower or
other figure. The points should not be allowed to touch the white cloth,
but should be made to fall upon the stem of a leaf, or some other dark
spot. These _rentrages_ are of four sorts:--1. One for the mordants, as
above; 2. one for topical colours; 3. one for the application of reds;
and, 4., one for the application of resist pastes or reserves. These
styles have superseded the old practice of pencilling.

The Perrotine is a machine for executing block-printing by mechanical
power; and it performs as much work, it is said, as 20 expert hands. I
have seen its operation, in many factories in France and Belgium, in a
very satisfactory manner; but I have reason to believe that there are
none of them as yet in this country. Three wooden blocks, from 2-1/2 to
3 feet long, according to the breadth of the cloth, and from 2 to 5
inches broad, faced with pear-tree wood, engraved in relief, are mounted
in a powerful cast-iron frame work, with their planes at right angles to
each other, so that each of them may, in succession, be brought to bear
upon the face, top, and back of a square prism of iron covered with
cloth, and fitted to revolve upon an axis between the said blocks. The
calico passes between the prism and the engraved blocks, and receives
successive impressions from them as it is successively drawn through by
a winding cylinder. The blocks are pressed against the calico through
the agency of springs, which imitate the elastic pressure of the
workman’s hand. Each block receives a coat of coloured paste from a
woollen surface, smeared after every contact with a mechanical brush.
One man, with one or two children for superintending the colour-giving
surfaces, can turn off about 30 pieces English per day, in three
colours, which is the work of fully 20 men and 20 children in block
printing by hand. It executes some styles of work to which the cylinder
machine, without the surface roller, is inadequate.

The copper-plate printing of calico is almost exactly the same as that
used for printing engravings on paper from flat plates, and being nearly
superseded by the next machine, need not be described.

[Illustration: 233]

The cylinder printing machine consists, as its name imports, of an
engraved copper cylinder, so mounted as to revolve against another
cylinder lapped in woollen cloth, and imbued with a coloured paste, from
which it derives the means of communicating coloured impressions to
pieces of calico passed over it. _Fig._ 233. will give the reader a
general idea of this elegant and expeditious plan of printing. The
pattern is engraved upon the surface of a hollow cylinder of copper, or
sometimes gun-metal, and the cylinder is forced by pressure upon a
strong iron mandrel, which serves as its turning shaft. To facilitate
the transfer of the impression from the engraving to the cotton cloth,
the latter is lapped round another large cylinder, rendered elastic by
rolls of woollen cloth, and the engraved cylinder presses the calico
against this elastic cushion, and thereby prints it as it revolves. Let
A be the engraved cylinder mounted upon its mandrel, which receives
rotatory motion by wheels on its end, connected with the steam or water
power of the factory. B is a large iron drum or roller, turning in
bearings of the end frames of the machine. Against that drum the
engraved cylinder A is pressed by weights or screws; the weights acting
steadily, by levers, upon its brass bearings. Round the drum B the
endless web of felt or blanket stuff _a a_, travels in the direction of
the arrow, being carried round along with the drum B, which again is
turned by the friction of contact with the cylinder A. _c_ represents a
clothed wooden roller, partly plunged into the thickened colour of the
trough D D. That roller is also made to bear, with a moderate force,
against A, and thus receives, by friction, in some cases, a movement of
rotation. But it is preferable to drive the roller C from the cylinder
A, by means of a system of toothed wheels attached to their ends, so
that the surface speed of the wooden or paste roller shall be somewhat
greater than that of the printing cylinder, whereby the colour will be
rubbed, as it were, into the engraved parts of the latter.

As the cylinder A is pressed upwards against B, it is obvious that the
bearers of the trough and its roller must be attached to the bearings of
the cylinder A, in order to preserve its contact with the colour-roller
C. _b_ is a sharp-edged ruler of gun-metal or steel, called the _colour
doctor_, screwed between two gun-metal stiffening bars; the edge of
which wiper is slightly pressed as a tangent upon the engraved roller A.
This ruler vibrates with a slow motion from side to side, or right to
left, so as to exercise a delicate shaving action upon the engraved
surface, as this revolves in the direction of the arrow. _c_ is another
similar sharp-edged ruler, called the _lint doctor_, whose office it is
to remove any fibres which may have come off the calico in the act of
printing, and which, if left on the engraved cylinder, would be apt to
occupy some of the lines, or at least to prevent the colour from filling
them all. This _lint doctor_ is pressed very slightly upon the cylinder
A, and has no traverse motion.

What was stated with regard to the bearers of the colour trough D,
namely, that they are connected, and moved up and down together with the
bearings of the cylinder A, may also be said of the bearers of the two
doctors.

The working of this beautiful mechanism may now be easily comprehended.
The web of calico, indicated in the figure by the letter _d_, is
introduced or carried in along with the blanket stuff _a a_, in the
direction of the arrow, and is moved onward by the pressure of the
revolving cylinder A, so as to receive the impression of the pattern
engraved on that cylinder.

Before proceeding to describe the more complex calico-machine which
prints upon cloth, 3, 4, or 5 colours at one operation, by the rotation
of so many cylinders, I shall explain the modern methods of engraving
the cylinder, which I am enabled to do by the courtesy of Mr. Locket, of
Manchester, an artist of great ingenuity in this department, who
politely allowed me to inspect the admirable apparatus and arrangements
of his factory.

To engrave a copper cylinder 3 or 4 inches in diameter, and from 30 to
36 inches long with the multitude of minute figures which exist in many
patterns, would be a very laborious and expensive operation. The happy
invention made by Mr. Jacob Perkins, in America, for transferring
engravings from one surface to another by means of steel roller dies,
was with great judgment applied by Mr. Locket to calico-printing, so
long ago as the year 1808, before the first inventor came to Europe with
the plan. The pattern is first drawn upon a scale of about 3 inches
square, so that this size of figure being repeated a definite number of
times, will cover the cylinder. This pattern is next engraved in
intaglio upon a roller of softened steel, about 1 inch in diameter, and
3 inches long, so that it will exactly occupy its surface. The engraver
aids his eye with a lens, when employed at this delicate work. This
roller is hardened by heating it to a cherry-red in an iron case
containing pounded bone-ash, and then plunging it into cold water; its
surface being protected from oxidizement by a chalky paste. This
hardened roller is put into a press of a peculiar construction, where,
by a rotatory pressure, it transfers its design to a similar roller in
the soft state; and as the former was in intaglio, the latter must be in
relievo. This second roller being hardened, and placed in an appropriate
volutory press, is employed to engrave by indentation upon the
full-sized copper cylinder, the whole of its intended pattern. The first
roller engraved by hand is called the _die_; the second, obtained from
it by a process like that of a milling tool, is called the _mill_. By
this indentation and multiplication system, an engraved cylinder may be
had for seven pounds, which engraved by hand would cost fifty or
upwards. The restoration of a worn-out cylinder becomes extremely easy
in this way; the mill being preserved, need merely be properly rolled
over the copper surface again.

At other times, the hard roller _die_ is placed in the upper bed of a
screw press, not unlike that for coining, while the horizontal bed below
is made to move upon strong rollers mounted in a rectangular iron frame.
In the middle of that bed a smooth cake or flat disc of very soft iron,
about 1 inch thick, and 3 or 4 inches in diameter, is made fast by four
horizontal adjusting screws, that work in studs of the bed frame. The
_die_ being now brought down by a powerful screw, worked by toothed
wheel-work, and made to press with force upon the iron cake, the bed is
moved backwards and forwards, causing the roller to revolve on its axles
by friction, and to impart its design to the cake. This iron disc is now
case-hardened by being ignited amidst horn shavings in a box, and then
suddenly quenched in water, when it becomes itself a die in relievo.
This disc die is fixed in the upper part of a screw press with its
engraved face downwards, yet so as to be movable horizontally by
traverse screws. Beneath this inverted bed, sustained at its upper
surface by friction-rollers, a copper cylinder 30 inches long, or
thereby, is mounted horizontally upon a strong iron mandrel, furnished
with toothed wheels at one of its ends, to communicate to it a movement
upon its axis through any aliquot arcs of the circle. The disc die being
now brought down to bear upon the copper cylinder, this is turned round
through an arc corresponding in length to the length of the die; and
thus, by the steady downward pressure of the screw, combined with the
revolution of the cylinder, the transfer of the engraving is made in
intaglio. This is I believe the most convenient process for engraving,
by transfer, the copper of a one-cylinder machine. But when 2, 3, or 4
cylinders are to be engraved with the same pattern for a two, three, or
four-coloured machine, the die and the mill roller plan of transfer is
adopted. In this case, the hardened roller die is mounted in the upper
bed of the transfer press, in such a way as to be capable of rotation
round its axis, and a similar roller of softened steel is similarly
placed in the under bed. The rollers are now made to bear on each other
by the action of the upper screw, and while in hard contact, the lower
one is caused to revolve, which, carrying round the upper by friction,
receives from it the figured impression in relief. When cylinders for a
three-coloured machine are wanted, three such _mills_ are made
fac-similes of each other; and the prominent parts of the figure which
belong to the other two copper cylinders are filed off in each one
respectively. Thus three differently figured _mills_ are very readily
formed, each adapted to engrave its particular figure upon a distinct
copper cylinder.

Some copper cylinders for peculiar styles are not graved by indentation,
as just described, but etched by a diamond point, which is moved by
mechanism in the most curious variety of configurations, while the
cylinder slowly revolves in a horizontal line beneath it. The result is
extremely beautiful, but it would require a very elaborate set of
drawings to represent the machinery by which Mr. Locket produces it. The
copper is covered by a resist varnish while being heated by the
transmission of steam through its axis. After being etched, it is
suspended horizontally by the ends, for about five minutes, in an oblong
trough charged with dilute nitric acid.

With regard to the two and three-coloured machines, we must observe,
that as the calico in passing between the cylinders is stretched
laterally from the central line of the web, the figures engraved upon
the cylinders must be proportionally shortened, in their lateral
dimensions especially, for the first and second cylinder.

Cylinder printing, though a Scotch invention, has received its wonderful
development in England, and does the greatest honour to this country.
The economy of labour introduced by these machines is truly marvellous;
one of them, under the guidance of a man to regulate the rollers, and
the service of a boy, to supply the colour troughs, being capable of
printing as many pieces as nearly 200 men and boys could do with blocks.
The perfection of the engraving is most honourable to our artisans. The
French with all their ingenuity and neat-handedness can produce nothing
approaching in excellence to the engraved cylinders of Manchester,--a
painful admission, universally made to me by every eminent manufacturer
in Alsace, whom I visited in my late tour.

Another modification of cylinder printing, is that with wooden rollers
cut in relief: it is called _surface printing_, probably because the
thickened colour is applied to a tense surface of woollen cloth, from
which the roller takes it up by revolving in contact with the cloth.
When the copper cylinders, and the wooden ones, are combined in one
apparatus, it has got the appropriate name of the _union_ printing
machine.

In mounting three or more cylinders in one frame, many more adjustments
become necessary than those described above. The first and most
important is that which ensures the correspondence between the parts of
the figures in the successive printing rollers, for unless those of the
second and subsequent engraved cylinders be accurately inserted into
their respective places, a confused pattern would be produced upon the
cloth as it advances round the pressure cylinder B, _figs._ 233, 234.

Each cylinder must have a forward adjustment in the direction of
rotation round its axis, so as to bring the patterns into correspondence
with each other in the length of the piece; and also a lateral or
traverse adjustment in the line of its axis, to effect the
correspondence of the figures across the piece; and thus, by both
together, each cylinder may be made to work symmetrically with its
fellows.

[Illustration: 234]

_Fig._ 234. is a cross section of a four-colour cylinder machine, by
which the working parts are clearly illustrated.

A A A is a part of the two strong iron frames or cheeks, in which the
various rollers are mounted. They are bound together by the rods and
bolts _a a a a_.

B is the large iron pressure cylinder, which rests with its gudgeons in
bearings or bushes, which can be shifted up and down in slots of the
side cheeks A A. These bushes are suspended from powerful screws _b_,
which turn in brass nuts, made fast to the top of the frame A, as is
plainly shown in the figure. These screws serve to counteract the strong
pressure applied beneath that cylinder, by the engraved cylinders D E.

C D E F are the four printing cylinders, named in the order of their
operation. They consist of strong tubes of copper or gun-metal, forcibly
thrust by a screw press upon the iron mandrels, round which as shafts
they revolve.

The first and last cylinder C and F are mounted in brass bearings, which
may be shifted in horizontal slots of the frame A. The pressure roller
B, against whose surface they bear with a very little obliquity
downwards, may be nicely adjusted to that pressure by its elevating and
depressing screws. By this means C and F can be adjusted to B with
geometrical precision, and made to press it in truly opposite
directions.

The bearings of the cylinders D and E are lodged also in slots of the
frame A, which point obliquely upwards, towards the centre of B. The
pressure of these two print cylinders C and F is produced by two screws
_c_ and _d_, which work in brass nuts, made fast to the frame, and very
visible in the figure. The frame-work in which these bearings and screws
are placed, has a curvilinear form, in order to permit the cylinders to
be readily removed and replaced; and also to introduce a certain degree
of elasticity. Hence the pressure applied to the cylinders C and F,
partakes of the nature of a spring; a circumstance essential to their
working smoothly, on account of the occasional inequalities in the
thickness of the felt web and the calico.

The pressure upon the other two print cylinders D and E is produced by
weights acting with levers against the bearings. The bearings of D are,
at each of their ends, acted upon by cylindrical rods, which slide in
long tubular bosses of the frame, and press with their nuts _g_ at their
under end upon the small arms of two strong levers G, which lie on each
side of the machine, and whose fulcrum is at _h_ (in the lower corner at
the left hand). The long arms of these levers G, are loaded with weights
H, whereby they are made to press up against the bearings of the roller
D, with any degree of force, by screwing up the nut _g_, and hanging on
the requisite weights.

The manner in which the cylinder E is pressed up against B, is by a
similar construction to that just described. With each of its bearings,
there is connected by the link _k_, a curved lever I, whose fulcrum or
centre of motion is at the bolt _l_. To the outer end of this lever, a
screw, _m_, is attached, which presses downwards upon the link _n_,
connected with the small arm of the strong lever _k_, whose centre of
motion is at _o_. By turning therefore the screw _m_, the weight L, laid
upon the end of the long arm of the lever K (of which there is one upon
each side of the machine), may be made to act or not at pleasure upon
the bearings of the cylinder E.

In tracing the operation of this exquisite printing machine, we shall
begin with the first engraved cylinder C. Its bearings or bushes shift,
as was already stated, in slots of the frame A. Each of them consists of
a round piece of iron, to which the end of the screw _c_ is joined, in
the same way as at _d_, in the opposite side. In each of these iron
bearings, a concave brass is inserted to support the collar of the
shaft, and in a dovetailed slit of this brass, a sliding piece is
fitted, upon which a set or adjusting screw in the iron bearing acts,
and which, being forced against the copper cylinder C, serves to adjust
the line of its axis, and to keep it steady between its bearings, and
true in its rotatory motion. Upon the iron bearing a plate is screwed,
provided with two flanges, which support the colour trough _q_, and the
colour roller M. This trough, as well as the others to be mentioned
presently, is made of sheet copper in the sides and bottom, and fixed
upon a board; but its ends are made of plates of cast copper or
gun-metal to serve as bearings to the colour roller M. The trough and
its roller may be shifted both together into contact with the printing
cylinder C, by means of the screw _r_. Near _s_, seen above the roller,
C, and _t_ below it, are sections of the two doctors, which keep the
engraved cylinders in sound working condition; the former being the
colour doctor, and the latter the lint doctor. Their ends lie in
brasses, which may be adjusted by the screws _u_ and V, working in the
respective brackets, which carry their brasses, and are made fast to the
iron bearings of the cylinder.

The pressure of the colour doctor is produced by two weights _w_ (see
high up on the frame work), which act on a pair of small levers _x_,
(one on each side of the machine,) and thus, by means of the chains,
tend to lift the arms _y_, attached to the end axles of the doctor. The
pressure of the lint doctor upon the cylinder C, is performed by the
screw _z_, pressing upon an arm which projects downwards, and is
attached to the axle of that doctor.

The bearings of the second printing cylinder D, consist at each end of a
mass of iron (removed in the drawing to show the mechanism below it),
which shifts in the slanting slot of the frame A. In each of these
masses there is another piece of iron, which slides in the transverse
direction, and may be shifted by the adjusting screw _a´_ fixed to it,
and working in a nut cast upon the principal bearing above described. To
the inner bearings, which carry the brasses in which the shaft lies, are
screwed the two curved arms _b´ b´_ to which are attached the bearings,
&c., for the colour trough, and the doctors. In these brasses there are
also dovetailed pieces, which slide and are pressed by set screws
furnished with square heads in the iron secondary bearings, which serve,
as before said, to adjust the printing cylinder in the line of its axis,
while other screws adjust the distance of the cloth upon which the
second colour is printed, and the line of contact with the cylinder B.

N, is the colour roller of D, and _d´_ the colour trough, which rests by
its board upon the lever _e´_; whose centres of motion _f´_, are made
fast to the curved arms _b´_, fixed at the bearings of the cylinder,
and whose ends are suspended by screws _g´_; whereby the colour roller
N, may be pressed with greater or less force to the cylinder D. _h´_ and
_i´_ are the two doctors of this cylinder; the former being the colour,
the latter the lint doctor. They rest, as was said of the cylinder C, in
brasses which are adjustable by means of screws, that work in the studs
or brackets by which the brasses are supported. These brackets must of
course be screwed to the secondary bearing-pieces, in order that they
may keep their position, into whatever direction the bearings may be
shifted. _k´_ and _l´_ are these set screws for the colour and lint
doctors. The pressure of the former upon the cylinder D, is produced by
weights _m´_, acting upon levers _n´_, and pressing by rods or links
_o´_, upon arms attached to each end of the axis of the doctor. (See the
left hand side of the figure near the bottom). The lint-doctor _i´_, is
pressed in a similar way at the other side upon the cylinder D, by the
weights acting upon levers _p´_, and by rods _q´_ upon arms fixed at
each end of the axis of the doctor.

The bearings of the third printing cylinder E, are of exactly the same
construction as that above described, and therefore require no
particular detail. The lint doctor _s_, is here pressed upon the
engraved cylinder by screws _t´_, working in the ends of studs or arms
fixed upon each end of the axis of the doctor, and pressing upon flanges
cast upon the brackets in which the brasses of the doctor’s axis lie,
which are made fast to the bearings of the cylinder E.

The bearings of the fourth copper cylinder F, are also constructed in a
similar way. Each consists of a first bearing, to which is joined the
end of the screw _d_, by which it is made to slide in a slot of the
frame. Another bearing, which contains the brass for the shaft of the
cylinder, can be shifted up and down in a transverse direction by a
screw _z´_, of the second bearing, working in a nut cast upon the first
bearing. To this secondary bearing, plates are made fast by the screws
_v´ v´_ to the inside, to carry the studs or brackets of the doctors
_x´_ and _y´_. In the brasses of the cylinder shaft, dovetailed pieces
are made to slide, being pressed by set screws _w´_, against the
engraved cylinder F, similar to what has been described for adjusting
the cylinders to one another. This cylinder has no separate colour
roller, nor trough, properly speaking, but the colour doctor _y´_ is
made concave to serve the purpose of a trough in supplying the engraved
lines of the cylinder with colour. With this view the top plate of the
doctor is curved to contain the coloured paste, and it is shut up at the
ends by pieces of wood made to fit the curvature of the doctor. Its
pressure against the engraved surface is produced by weights _a´´_,
acting at the ends of arms _b´´_, attached to the ends of the axis of
the doctor. The pressure of the lint doctor _x´_ is given by screws
_c´´_, working in arms attached to the ends of the axis of the doctor,
and pressing upon the flanges _d´´_, cast upon the brackets which carry
the brasses for the axis of the doctor. These brasses are themselves
adjustable, like those of all the other cylinders, by set screws in the
brackets, which work in the nuts formed in the brasses.

_e´´ e´´_, is the endless web of felt stuff which goes round the
cylinder B, and constitutes the soft elastic surface upon which the
printing cylinders C, D, E, and F exercise their pressure. This endless
felt is passed over a set of rollers at a certain distance from the
machine, to give opportunity for the drying up of any colouring paste
which it may have imbibed from the calico in the course of the
impressions. In its return to the machine in the direction of the arrow,
it is led over a guide roller _o_, which is thereby made to revolve.
Upon the two ends of this, and outside of the bearings which are fixed
upon the tops of the frame A, are two eccentrics, one of which serves to
give a vibratory traverse movement to the colour doctors _s´_, _h´_, and
_r´_ of the three cylinders, C, D, and E whilst the other causes the
colour doctor _y´_ of the cylinder F, to make lateral vibrations.

[Illustration: 235]

Q is one of a pair of cast-iron brackets, screwed on at the back of the
side-frames or cheeks A A, to carry the roller filled with white calico
R, ready for the printing operations. Upon the end of the shaft whereon
the calico is coiled, a pulley is fixed, over which a rope passes
suspending a weight in order to produce friction, and thereby resistance
to the action which tends to unwind the calico. In winding it upon that
and similar rollers, the calico is smoothed and expanded in breadth by
being passed over one or more grooved rods, or over a wooden bar S,
_fig._ 235. the surface of which is covered with wire, so as to have the
appearance of a united right and left-handed screw. By this device, the
calico, folded or creased at any part, is stretched laterally from the
centre, and made level. It then passes over the guide-roller _o_, where
it comes upon the surface of the felt _e´´ e´´_, and thence proceeds
under its guidance to the series of printing cylinders.

Three and four-colour machines, similar to the above, are now at work in
many establishments in Lancashire, which will turn off a piece of 28
yards per minute, each of the three or four cylinders applying its
peculiar part of the pattern to the cloth as it passes along, by
ceaseless rotation of the unwearied wheels. At this rate, the
astonishing length of one mile of many-coloured web is printed with
elegant flowers and other figures in an hour. When we call to mind how
much knowledge and skill are involved in this process, we may fairly
consider it as the greatest achievement of chemical and mechanical
science.

Before entering upon the different styles of work which constitute
calico printing, I shall treat, in the first place, of what is common to
them all, namely, the thickening of the mordants and colours. This is an
operation of the greatest importance towards the successful practice of
the art. Several circumstances may require the consistence of the
thickening to be varied; such as the nature of the mordant, its density,
and its acidity. A strong acid mordant cannot be easily thickened with
starch; but it may be by roasted starch, vulgarly called British gum,
and by gum arabic or senegal. Some mordants which seem sufficiently
inspissated with starch, liquefy in the course of a few days; and being
apt to run in the printing-on make blotted work. In France, this evil is
readily obviated, by adding one ounce of spirits of wine to half a
gallon of colour; a remedy which the English excise duties render too
costly.

The very same mordant, when inspissated to different degrees, produces
different tints in the dye-copper; a difference due to the increased
bulk from the thickening substance; thus, the same mordant, thickened
with starch, furnishes a darker shade than when thickened with gum. Yet
there are circumstances in which the latter is preferred, because it
communicates more transparency to the dyes, and because, in spite of the
washing, more or less of the starch always sticks to the mordant. The
gum has the inconvenience, however, of drying too speedily, and of also
increasing too much the volume of the mordants; by both of which causes
it obstructs their combination with the stuff, and the tints become thin
or scratchy.

The substances generally employed as thickeners, are the following:--

   1. Wheat starch.
   2. Flour.
   3. Roasted starch.
   4. Gum senegal.
   5. Gum tragacanth.
   6. Salep.
   7. Pipe-clay, mixed with gum senegal.
   8. Sulphate of lead.
   9. Sugar.
  10. Molasses.
  11. Glue.

After thickening with gum, we ought to avoid adding metallic solutions
in the liquid state; such as nitrate of iron, of copper, solutions of
tin, of subacetate of lead, &c.; as they possess the property of
coagulating gum. I shall take care to specify the nature and proportion
of thickening to be employed for each colour; a most important matter,
hitherto neglected by English writers upon calico printing.

The atmosphere of the printing shops should never be allowed to cool
under 65° or 70° F.; and it should be heated by proper stoves in cold
weather, but not rendered too dry. The temperature and moisture should
therefore both be regulated with the aid of thermometers and
hygrometers, as they exercise a great influence upon all the printing
processes, and especially upon the combination of the mordant with the
cloth. In the course of the desiccation, a portion of the acetic acid
evaporates with the water, and subacetates are formed, which combine
with the stuff in proportion as the solvent principle escapes; the water
as it evaporates carries off acetic acid with it, and thereby aids the
fixation of bases. These remarks are peculiarly appropriate to delicate
impressions by the cylinder machine, where the printing and drying are
both rapidly effected. In the lapis lazuli style, the strong mordants
are apt to produce patches, being thickened with pipe-clay and gum,
which obstruct the evaporation of the acids. They are therefore apt to
remain, and to dissolve a portion of the mordants at their immersion in
the blue vat, or at any rate, in the dung bath. In such a case a hot and
humid air is indispensable, after the application of the mordants; and
sometimes the stuffs so impregnated, must be suspended in a damp
chamber. To prevent the resist pastes becoming rapidly crusty,
substances apparently useless are mixed with them, but which act
beneficially by their hygrometric qualities, in retarding the
desiccation. Oil also is sometimes added with that view.

It is often observed that goods printed upon the same day, and with the
same mordant, exhibit inequalities in their tints. Sometimes the colour
is strong and decided in one part of the piece, while it is dull and
meagre in another. The latter has been printed in too dry an atmosphere.
In such circumstances a neutral mordant answers best, especially if the
goods be dried in a hot flue, through which humid vapours are in
constant circulation.

In padding, where the whole surface of the calico is imbued with
mordant, the drying apartment or flue, in which a great many pieces are
exposed at once, should be so constructed as to afford a ready outlet to
the aqueous and acid exhalations. The cloth ought to be introduced into
it in a distended state; because the acetic acid may accumulate in the
foldings, and dissolve out the earthy or metallic base of the mordant,
causing white and gray spots in such parts of the printed goods. Fans
may be employed with great advantage, combined with HOT FLUES. (See this
article.)

In the colour laboratory, all the decoctions requisite for the print
work should be ready prepared. They are best made by a steam heat, by
means of copper boilers of a cylindric form, rounded at the bottom, and
encased within a cast-iron cylinder, the steam being supplied to the
space between the two vessels, and the dye-stuff and water being
introduced into the interior one, which for some delicate purposes may
be made of tin, or copper tinned inside. A range of such steam apparatus
should be placed either along one of the side walls, or in the middle
line of the laboratory. Proper tables, drawers, phials, with chemical
reagents, measures, balances, &c., should also be provided. The most
useful dye-extracts are the following:--

Decoction of logwood, of Brazil wood, of Persian berries, of quercitron
bark, of nut-galls, of old fustic, of archil or cutbear, of cochineal,
of cochineal with ammonia, of catechu.

The following mordants should also be kept ready prepared:--

  1. Aluminous mordant.
     Take 50 gallons of boiling water.
          100 lbs. of alum.
          10 lbs. of soda crystals.
          75 lbs. of acetate of lead.

The soda should be added slowly to the solution of the alum in the
water, and when the effervescence is finished, the pulverized acetate of
lead is put in and well stirred about till it be all dissolved and
decomposed. During the cooling, the mixture should be raked up a few
times, and then allowed to settle. The supernatant liquor is the
mordant; it has a density of 11° or 11-1/2° Baumé. It serves for reds
and pinks, and enters into the composition of puce and lilac.

  2. Aluminous mordant.
     Take 50 gallons of water.
          100 lbs. of alum.
          10 lbs. of soda crystals.
          100 lbs. of acetate of lead;--operate as above directed.

The supernatant liquor here has a density of 12° Baumé; it is employed
for lapis resists or reserves, and the cylinder printing of madder reds.

  3. Aluminous mordant.
     Take 50 gallons of water.
          100 lbs. of alum.
          6 lbs. of soda crystals.
          50 lbs. of acetate of lead;--operate as above directed.

This mordant is employed for uniform yellow grounds.

4. Aluminous mordant.

This is made by adding potash to a solution of alum, till its earth
begins to be separated, then boiling the mixture to precipitate the
subsulphate of alumina, which is to be strained upon a filter, and
dissolved in acetic acid of moderate strength with the aid of heat. This
mordant is very rich in alumina, and marks 20° B.

  5. Aluminous mordant.
     Take 12-1/2 gallons of water.
          100 lbs. of alum.
          150 lbs. of liquid pyrolignite of lime at 11-1/2° Baumé.

This mordant is made with heat like the first; after cooling, some alum
crystallizes, and it marks only 12-1/2° B.

A mordant is made by solution of alum in potash, commonly called--

6. Aluminate of potash. The caustic lye is prepared by boiling together
for an hour 100 gallons of water, 200 lbs. of potash, and 80 lbs. of
quicklime; the mixture is then allowed to settle, the supernatant liquor
is decanted, and evaporated till its density be 35° B. In 30 gallons of
that lye at a boiling heat, 100 lbs. of ground alum are to be dissolved.
On cooling, crystals of sulphate of potash separate. The clear liquor is
to be decanted off, and the crystals being washed with a little water,
this is to be added to the lye. About 33 gallons of mordant should be
obtained.

_Mordant for Black._

The pyrolignite of iron called iron liquor in this country, is the only
mordant used in calico-printing for black, violet, puce, and brown
colours. The acetate of alumina, prepared from pyrolignous acid, is much
used by the calico-printers under the name of red or yellow liquor,
being employed for these dyes.

We may observe that a strong mordant, like No. 2., does not keep so well
as one of mean density, such as No 1. Too much mordant relatively to the
demands of the works should therefore not be made at a time.

There are eight different styles of calico-printing, each requiring
different methods of manipulation, and peculiar processes.

1. The madder style, to which the best chintzes belong, in which the
mordants are applied to the white cloth with many precautions, and the
colours are afterwards brought up in the dye-bath. These constitute
permanent prints.

2. The padding or _plaquage_ style, in which the whole surface of the
calico is imbued with a mordant, upon which afterwards different
coloured figures may be raised, by the topical application of other
mordants joined to the action of the dye-bath.

3. The reserve style, where the white cloth is impressed with figures in
resist paste, and is afterwards subjected first to a cold dye, as the
indigo vat, and then to a hot dye-bath, with the effect of producing
white or coloured spots upon a blue ground.

4. The discharge or _rongeant_ style, in which thickened acidulous
matter either pure or mixed with mordants, is imprinted in certain
points upon the cloth, which is afterwards padded with a dark-coloured
mordant, and then dyed, with the effect of showing bright figures on a
darkish ground.

5. China blues; a style resembling blue stone-ware, which requires very
peculiar treatment.

6. The decolouring or _enlevage_ style; by the topical application of
chlorine or chromic acid to dyed goods. This is sometimes called a
discharge.

7. Steam colours; a style in which a mixture of dye extracts and
mordants are topically applied to calico, while the chemical reaction
which fixes the colours to the fibre is produced by steam.

8. Spirit colours; produced by a mixture of dye extracts, and solution
of tin, vulgarly called spirit by dyers. These colours are brilliant but
fugitive.

I. The madder style; called by some dip colours. The true chintz
patterns belong to it; they have from 5 to 7 colours, several of which
are grounded-in after the first dye has been given in the madder bath.

In dyeing with madder; sumach, fustic or quercitron, is sometimes added
to the bath, in order to produce a variety of tints with the various
mordants at one operation.

1. Suppose we wish to produce flowers or figures of any kind containing
red, purple, and black colours, we may apply the three mordants at once,
by the three-colour cylinder machine, putting into the first trough
acetate of alumina thickened; into the second, acetate of iron; and into
the third, a mixture of the two; then drying in the air for a few days
to fix the iron, dunging, and dyeing up in a bath of madder and sumach.
If we wish to procure the finest madder reds and pinks, besides the
purple and black, we must apply at first only the acetate of alumina of
two densities, by two cylinders, dry, dung, and dye up, in a madder
bath. The mordants of iron liquor for the black, and of iron liquor
mixed with the aluminous for purple, must be now grounded-in by blocks,
taking care to insert these mordants into their precise spots: the goods
being then dried with airing for several days, and next dunged, are dyed
up in a bath of madder and sumach. They must be afterwards cleared by
branning. See BRAN, DUNGING, and MADDER.

2. Suppose we wish to produce yellow with red, pink, purple and black;
in this case the second dye-bath should contain quercitron or fustic,
and the spots intended to be yellow should receive the acetate of
alumina mordant.

3. The mordant for a full red may be acetate of alumina, of spec. grav.
1·055 thickened with starch, and tinged with Brazil wood; that for a
pale red or pink, the same at spec. gravity 1·014, thickened with gum;
that for a middling red, the same at spec. gravity, 1·027, thickened
with British gum; and for distinction’s sake, it may be tinged yellow
with Persian berries. The mordant for black is a pyrolignous acetate of
iron, of specific gravity 1·04; for purple the same, diluted with six
times its volume of water; for chocolate, that iron liquor mixed with
acetate of alumina, in various proportions according to the shade
wanted. Sumach is mixed with the madder for all these colours except for
the purple. The quantity of madder required varies according to the body
of colour to be put upon the cloth, being from one pound per piece to
three or even four. The goods must be entered when the copper is cool,
be gradually heated during two or three hours, up to ebullition, and
sometimes boiled for a quarter of an hour; the pieces being all the
while turned with a wince from the one side of the copper to the other.
(See WINCE.) They are then washed and boiled in bran and water for ten
or fifteen minutes. When there is much white ground in the chintz, they
must be branned a second or even a third time, with alternate washing in
the dash-wheel. To complete the purification of the white, they are
spread upon the grass for a few days; or what is more expeditious, and
equally good if delicately managed, they are winced for a few minutes in
a weak solution of chloride of lime.

4. In the grounding-in for yellow, after madder reds, the aluminous
mordant being applied, &c., the piece is dyed, for about an hour, with
one pound of quercitron bark, the infusion being gradually heated to
150° or 160°, but not higher.

5. A yellow is sometimes applied in chintz work after the other colours
are dyed, by means of a decoction of Persian berries mixed with the
aluminous mordant, thickened with flour or gum, and printed-on with the
block; the piece, when dry, is passed through a weak carbonated alkaline
water, or lime water, then washed and dried for the market.

6. _Black mordant._--Take half a gallon of acetate of iron, of spec.
grav. 1·04, 4 ounces of starch, and 4 ounces of flour. The starch must
first be moistened with the acetate, then the flour must be added, the
rest of the acetate well mixed with both, and the whole made to boil
over a brisk fire for five minutes, stirring meanwhile to prevent
adhesion to the bottom of the pot. The colour must be poured into an
earthen pipkin, and well mixed with half an ounce of gallipoli oil. In
general, all the mordants, thickened with starch and flour, must be
boiled, for a few minutes. With British gum or common gum, they must be
heated to 160° F., or thereby, for the purpose merely of dissolving
them. The latter should be passed through a sieve to separate the
impurities often present in common gum.

7. _Puce mordant._--Take a quart of acetate of alumina and acetate of
iron, each of spec. grav. 1·04, mixed and thickened like the black, No.
6. To give the puce a reddish tinge, the acetate of alumina should have
a specific gravity of 1·048, and the iron liquor only 1·007.

Red mordants are thickened with British gum, and are sufficiently
coloured with the addition of any tingeing decoction.

8. _Violet mordants._--These consist either of a very weak solution of
acetate of iron, of spec. gravity 1·007, for example; or of a little of
the stronger acetate of 1·04, mixed with acetate of alumina, and a
little acetate of copper, thickened with starch or British gum. The
shades may be indefinitely varied by varying the proportions of the
acetates.

When black is one of the colours wanted, its mordant is very commonly
printed-on first, and the goods are then hung upon poles in the
drying-room, where they are aired for a few days, in order to fix the
iron by its peroxidizement; the mordants for red, violet, &c., are then
grounded in, and the pieces are dyed up, after dunging and washing, in
the madder bath, into which, for certain shades, sumach, galls, or
fustic, is added. The goods are brightened with a boil in soap water;
occasionally also in a bath, containing a small quantity of solution of
tin or common salt. The following mode of brightening is much extolled
by the French, who are famous for their reds and roses.

1. A soap boil of forty minutes, at the rate of 1 pound for every 2
pieces. Rinse in clear water.

2. Pass through chloride of soda solution of such strength that two
parts of it decolour one part of Gay Lussac’s test liquor. See CHLORIDE
OF LIME and INDIGO. Wince the pieces through it for 40 minutes. Rinse
again.

3. Pass it again through the soap bath, No. 1.

4. Brighten it in a large bath of boiling water, containing 4 pounds of
soap, and 1 pound of a cream-consistenced salt of tin, containing nearly
half its weight of the muriate of tin, combined with as much nitric acid
of spec. grav. 1·288. This strong nitro-muriate having been diluted with
a little water, is to be slowly poured into the bath of soap water, and
well mixed by stirring. The pieces are now put in, and winced through it
for one half, or three quarters of an hour.

5. Repeat the soap boil, No. 1. Rinse and dry.

9. _Grounding in of Indigo blue._

Take half a gallon of water of 120° F., 8 ounces of ground indigo, and 8
ounces of red sulphuret of arsenic (orpiment), 8 ounces of quicklime,
mix together, and heat the mixture to the boiling point; withdraw from
the fire, and add, when it is lukewarm, 6 ounces of carbonate of soda,
stir and leave the whole at rest till the next day. Then decant the
clear liquor, and thicken every quart of it with half a pound of gum.
This colour ought to be green, and be preserved in a close vessel. When
used it is put into a pot with a narrow orifice, the pencil is dipped
into it, wiped on the edge of the pot, and immediately applied by hand.
This plan is tedious, and is nearly superseded by the following
grounding blue.

Take half a gallon of caustic soda lye of spec. grav. 1·15, heated to
120° F.

12 ounces of hydrate of protoxide of tin, obtained by precipitating it
from the muriate of tin by solution of potash.

[Illustration: 236 237]

8 ounces of ground indigo; heat these mixed ingredients to the boiling
point, then move the pot off and on the fire two or three times in
succession, and finally thicken, with 3 pounds of raw sugar. In order to
apply this by the block, the following apparatus is employed, called the
_canvass frame_; _figs._ 236. 237. It is formed of a copper case or box
A, in which is laid a frame B, filled with pretty stout canvass. The box
communicates by a tube with the cistern C, mounted with a stop-cock D.
_Fig._ 237. represents the apparatus in plan: A, the box; B, the
canvass, with its edges _a a a a_, fixed by pin points to the sides. The
colour is _teared_ (_tiré_), or spread even, with a wooden scraper as
broad as the canvass. In working with this apparatus, the colour being
contained in the vessel C is drawn off into the case A, by opening the
stop-cock D, till it rises to the level of the canvass. The instant
before the printer daubs the block upon the canvass, the _tearer_
(_tireur_), boy or girl, runs the scraper across it to renew its
surface; and the printer immediately transfers the colour to the cloth.
In this kind of printing great skill is required to give evenly
impressions. As the blue is usually applied to somewhat large designs,
it is very apt to run; an inconvenience counteracted by dusting fine dry
sand upon the cloth as soon as it is blocked. The goods must be washed
within 24 hours after being printed.

10. _Topical grounding blue for the cylinder press._

  Take 3-1/2 gallons of caustic soda lye of spec. grav. 1·15.
       3-1/2 lbs. of ground indigo.
       5 lbs. of precipitated protoxide of tin (as above).

Boil the mixed ingredients for ten minutes, take them from the fire, and
add, first, 3 lbs. of Venice turpentine; then 11 lbs. of gum.

Put this mixture into the colour trough, print with it, and after two
days wash in the dash-wheel; then pass it through a soap bath, along
with a little soda, to brighten the blue, and to take off its greyish
tint.

The use of the turpentine is easily explained; it serves to exclude the
atmospherical oxygen, and prevent the regeneration of the indigo blue,
before it is spread upon the cloth.

After the application to white calico of a similar blue, into which a
little acid muriate of tin has been put, the goods are dipped for ten
minutes in thin milk of lime, shaking the frame all the time. They are
then washed, and cleared with a soap boil. The following colour remains
long in the deoxidized state from its containing 8 ounces of indigo, 10
ounces of hydrated protoxide of tin, and 1-1/2 pounds of solution of
muriate of tin, to 2 quarts of soda lye of 1·15, thickened with 2-1/2
pounds of gum. This blue may be applied by either the block or the
cylinder.

11. Topical Prussian blue for grounding.

2 quarts of water with 8 ounces of starch, are to be mixed and boiled;
add 2-1/4 ounces of a liquid Prussian blue colour, prepared by
triturating three quarters of an ounce of that pigment with as much
muriatic acid, leaving the ingredients to react upon each other for 24
hours, and then adding three quarters of an ounce of water.

Add 4 ounces of liquid perchloride of tin (oxymuriate).

Mix all together, and pass through a searce. This colour is not very
fast; cloth printed with it will bear only rinsing.

12. Prussian blue figures are impressed as follows:--

Dissolve 8 ounces of sulphate of iron, and as much acetate of lead,
separately in 2 quarts of boiling water; mix well, and settle. Take one
quart of this clear liquor reduced to spec. grav. 1·02, one quart of
mucilage containing 3 pounds of gum, coloured with a little prussiate of
potash, mix into a mordant, and print it on with the cylinder. Two days
afterwards wash in tepid water containing a little chalk, and then pass
the cloth through a solution of prussiate of potash in water, sharpened
with a little muriatic acid, till it takes the desired hue. Finally
rinse.

II. The padding or _plaquage_ style, called _foulard_ also by the
French. See PADDING.

Any mordant whatever, such as the acetates of alumina, or of iron, or
their mixture, may be applied to the piece by the padding machine, after
which it is dried in the HOT-FLUE, washed, dunged, dyed, washed, and
brightened.

Colours from metallic oxides are very elegantly applied by the padding
process. Thus the iron buff, the manganese bronze, and the chrome
yellows and greens are given.

1. Iron buff or chamois.

  Take  50 gallons of boiling water;
       150 pounds of sulphate of iron; dissolve along with
        10 pounds of alum; which partly saturate by the gradual
           addition of
         5 pounds of crystals of soda; and in this mixture dissolve
        50 pounds of pyrolignous acetate of lead. Allow the whole to
           settle, and draw off the clear supernatant liquid.

For furniture prints this bath should have the spec. grav. 1·07.

The calico being padded in it, is to be dried in the hot-flue; and after
48 hours suspension is to be washed in water at 170° containing some
chalk, by the wince apparatus. It is then washed, by the same apparatus,
in hot water, containing a pailful of soda lye of spec. grav. 1·04.

For light tints the padding liquor should be reduced to the spec. grav.
1·01. The dye in either case may be brightened by wincing through a weak
solution of chloride of lime.

Nitrate of iron diffused through a body of water may be also used for
padding, with alternate washings in water, and a final wincing in a weak
alkaline lye.

With a stronger solution, similar to the first, the boot-top colour is
given.

2. The bronze or _solitaire_.

The goods are to be padded in a solution of the sulphate or muriate of
manganese, of a strength proportional to the shade desired, dried in the
hot-flue, and then raised by wincing them in a boiling-hot caustic lye,
of spec. grav. 1·08, and next through a weak solution of chloride of
lime, or soda. They are afterwards rinsed. Instead of passing them
through the chloride, they may be merely exposed to the air till the
manganese attracts oxygen, then rinsed, and dried.

When the manganese solution has the density of 1·027, it gives a light
shade; at the density of 1·06, a shade of moderate depth, and at 1·12 a
dark tint.

The texture of the stuff is apt to be injured during the oxidation of
the manganese.

3. _Carmelite_ is obtained by padding in a mixture of muriate or
sulphate of manganese and acetate of iron, then proceeding as above.

4. _Copper green_ is given by padding in a mixed solution of sulphate
and acetate of copper with a little glue, drying in the hot-flue, and
next day padding in a caustic lye of spec. grav. 1·05. The goods are
then rinsed, and padded through a solution made with 8 ounces of
arsenious acid combined with 4 ounces of potash diluted with 2 gallons
of water. They are finally rinsed and dried.

5. Olive and cinnamon colours are given by padding through mixed
solutions of the acetate of iron and sulphate of copper; drying, and
padding in a caustic lye of spec. grav. 1·05.

6. _Green and solitaire_ form a pleasing umber, or hellebore shade,
which may be obtained by padding through a mixed solution of manganese
and aceto-sulphate of copper and raising the shades, as above
prescribed.

7. _Chrome yellow._

Pad in a solution of bichromate of potash containing 8 ounces of it to
the gallon of water; then dry with moderate heat, and pad in a solution
of acetate or nitrate of lead, containing 6 or 8 ounces in the gallon of
water; wash, and dry. Or we may pad first in a solution of acetate of
lead containing a little glue; dry, and pad in solution of bichromate of
potash. Then rinse. The last process is apt to occasion cloudiness. To
obtain a light lemon tint, we must pad in a solution of acetate of lead
of double the above strength, or 16 ounces to the gallon, then wince the
pieces through weak milk of lime, rince, pad through bichromate of
potash, rinse, and dry.

8. _Chrome orange._

Pad through a mixed solution of the subacetate and acetate of lead,
three times in succession, and dry in the hot-flue; then wince for ten
minutes through weak milk of lime; rinse; wince for a quarter of an hour
in a warm solution of bichromate of potash; and finally raise the colour
by wincing the goods through hot lime water.

9. _Prussian blue._

Pad in the preceding chamois liquor of the spec. grav. 1·007; dry in the
hot-flue; wince well in chalky water at 160° F., and then dye by wincing
in the following liquor:--

Dissolve 5 ounces of prussiate of potash, in 25 gallons of water heated
to 90° or 100°, adding 2 ounces of sulphuric acid; afterwards rinse, and
brighten in a very dilute sulphuric acid.

10. _Green_ is given by padding goods, previously dyed in the indigo
vat, in a solution of acetate of lead containing a little glue; and then
padding them in a warm solution of bichromate of potash; finally rinsing
and drying.

III. Resist pastes or reserves; these are subservient to the cold indigo
vat, and they may be distributed under four heads; 1. fat reserves; 2.
reserves with bases of metallic salts; 3. coloured reserves capable of
assuming different tints in the dyeing; 4. reserves with mordants, for
the cloth to be afterwards subjected to a dyeing bath, whereby variously
coloured figures are brought up on a blue ground, so as to resemble the
mineral called _lazulite_; whence the name _lapis_ or lapis lazuli.

1. The fatty resists are employed in the printing of silk; which see
_infra_.

2. With regard to reserves the following general observations may be
made. After printing-on the paste, the goods must be hung up in a
chamber, rather humid than too dry, and left there for a certain time,
more or less, according to the nature of the reserve. In dipping them
into the blue vat, if the reserve be too dry, it is apt to swell, scale
off, and vitiate the pattern. This accident is liable to happen also
when the vat is deficient in lime, especially with deep blues.

1. _Simple white resist paste_ for a full body of blue.

  Take 1 gallon of water, in which are to be dissolved,
       1 pound of binacetate of copper (distilled verdigris), and 3
         libs. of sulphate of copper.
       This solution is to be thickened with
       2 libs. of gum senegal, 1 lib. of British gum, and 4 libs. of
         pipe-clay; adding afterwards, 2 ounces of nitrate of copper--as
         a deliquescent substance.

2. _White reserve for light blues._

  Take 1 gallon of water, in which dissolve
       4 ounces of binacetate of copper,
       1 lib. of sulphate of copper; and thicken this solution with
       2 libs. of gum senegal, 1 lib. of British gum, and 4 libs. of
         pipe-clay.

3. _White reserve for the cylinder machine._

  Take 1-1/2 gallons of water; in which dissolve
       2-1/2 libs. of binacetate of copper,
       10 libs. of sulphate of copper; and add to the solution
       6 libs. of acetate of lead; then thicken with
       10 libs. of gum; adding afterwards 10 libs. of sulphate of lead.

After printing-on this reserve, the goods are to be hung up for two
days, then dipped till the proper blue tint be obtained. Finally they
must be winced through dilute sulphuric acid to clear up the white, by
removing the cupreous tinge.

3. Coloured reserves.

1. _Chamois reserve._

  Take 1 gallon of the chamois bath (No. 1. page 226, at bottom); to
         which add
       8 ounces of nitrate of copper,
       24 ditto of muriate of zinc; thicken with
       6 pounds of pipe clay, and 3 libs. of gum senegal.

After printing-on this paste, the goods must be hung up for five or six
days in a somewhat damp room. Then after having dipped them in the vat,
they are to be steeped in water for half an hour, and slightly washed.
Next wince for half an hour, through water at 100° F. containing 2
pounds of soda crystals per 30 gallons. Rinse and dry.

2. _Chrome yellow reserve._

  Take 1 gallon of water; in which dissolve
       3 libs. of nitrate of lead,
       1 lib. of binacetate of copper; to the solution, add
       1/2 lib. of subacetate of lead; and thicken the mixed solution
         with
       3 libs. of gum.
       6 libs. of pipe clay. Grind all the ingredients together, and
         pass through a searce.

After treating the goods as in No. 1., they must be winced for half an
hour in a solution containing 5 ounces of bichromate of potash, per
piece of calico, and also in a dilute muriatic bath, till the chrome
yellow become sufficiently bright.

A chrome orange reserve may be made by introducing a larger proportion
of subacetate of lead, and passing the reserve printed goods through
weak milk of lime, as already prescribed for producing an orange by
chrome.

The basis of the resist pastes used at Manchester is sometimes of more
complex composition than the above; since, according to the private
information I received from an extensive calico printer, they contain
“china clay” (instead of pipe-clay which often contains iron) strong
solution of sulphate of copper, oil, tallow, and soap; the whole
incorporated by trituration with heat.

In the Lancashire print-works, a little tartaric acid is added to the
nitrate of lead, which prevents the colour from taking a dingy cast.

4. _Reserves with mordants_, or the lazulite style.

1. _Black upon a blue ground._

At Manchester the black pattern is printed-on with a mixture of iron
liquor and extract of logwood, and the resist paste by the cylinder
machine; in France the black is given by the following recipe:--

  Take 1 gallon of decoction of galls of spec. grav. 1·04, mixed and
         boiled into a paste with
       14 ounces of flour; into the paste, when nearly cold, there are
         added,
       8 ounces of an acetated peroxide of iron, made by adding 1 lib.
         acetate of lead to 3
       libs. of nitrate of iron, spec. grav. 1·56.
       1/8 ounce of gallipoli oil.

This topical black forms a fast colour, and resists the fine blue vat,
weak potash lye, bichromate of potash, boiling milk of lime, dunging and
maddering.

The preceding answers best for the block; the following for the
cylinder,--

  2. Take 1 gallon decoction of galls of spec. grav. 1·056.
     18 ounces of flour, mix, boil into a paste, to which, when cool,
       add
     8 ounces of the aceto-nitrate of iron of the preceding formula, and
     1 quart of iron liquor of spec. grav. 1·110.

In Lancashire a little prussiate of potash is sometimes added to nitrate
of iron and decoction of logwood; and the goods are after washing, &c.
finished by passing through a weak solution of bichromate of potash. The
chromic acid gives depth and permanence to the black dye, being supposed
to impart oxygen to the iron, while it does not affect any of the other
colours that may happen to be impressed upon the cloth, as solution of
chloride of lime would be apt to do. The solution of the bichromate
deepens the spirit purples into blacks, and therefore with such delicate
dyes becomes a very valuable application. This interesting fact was
communicated to me by an eminent calico-printer in Lancashire.

Having premised the composition of the topical black dye, we are now
prepared to apply it in the lazulite style.

1. _Black resist._

  Take 1 gallon of the above black without the flour,
       2 ounces of sulphate of copper,
       1 ounce of muriate of ammonia, dissolve and thicken with
       4 pounds of pipe-clay and 2 pounds of gum.

Another good formula is the following:--

  Take 1 gallon of iron liquor of 1·056 spec. grav. dissolve in it,
       2 ounces of binacetate of copper,
       8 ounces of sulphate of copper; and thicken as just described.

2. _Puce reserve_ paste, contains acetate of alumina mixed with the iron
liquor.

3. _Full red reserve._

  Take 1 gallon of acetate of alumina, (made with 50 gallons water, 100
         libs. alum, 10 libs. soda crystals, and 100 libs. acetate of
         lead; the supernatant liquid being of spec. grav. 1·085);
         dissolve in it
       4 ounces of corrosive sublimate; thicken with
       2 pounds of gum senegal,
       4 pounds of pipe-clay, and mix in 8 ounces of gallipoli oil.

4. _Reserve paste for a light red._

  Take 1 gallon of the weaker sulpho-acetate of alumina formerly
         prescribed; dissolve in it
       4 ounces of corrosive sublimate; and thicken with
       4 pounds of pipe-clay, and 2 pounds of gum; adding to the mixture
       8 ounces of oil.

5. _Neutral resist paste._

  Take 1 gallon of water; in which dissolve,
       3-1/4 libs. of binarseniate of potash, and
       12 ounces of corrosive sublimate; thicken with
       3 libs. of gum, and 6 libs. of pipe-clay, adding to the paste 16
         ounces of oil.

6. _Carmelite reserve paste._

  Take 1 half gallon of acetate of alumina spec. grav. 1·014; (see
         second aluminous mordant p. 224).
       1 half gallon iron liquor of spec. grav. 1·027; dissolve in them
       4 ounces of sulphate of copper, 4 ounces of verdigris, and 1
         ounce of nitrate of copper; thicken with
       2 libs. of gum,
       4 libs. of pipe-clay.

7. _Neutral reserve paste._

  Take 1 gallon of water; dissolve in it,
       44 ounces of binarseniate of potash, and
       12 ounces of corrosive sublimate; thicken with
       3 libs. of gum,
       6 libs. of pipe-clay,
       16 oz. of oil.

To explain fully the manipulation of the lazulite style, we shall
suppose that the calicoes are printed with the following reserves, taken
in their order:--

  1. Black reserve,     No. 1. above.
  2. Full red reserve,  No. 3.
  3. Light red reserve, No. 4.
  4. Neutral reserve,   No. 7.

Four days after printing-on these reserves, the goods must be twice
dipped in the blue vat, ten minutes in and ten minutes out each time;
but more dips may be given according to the desired depth of shade. The
cloth must be afterwards rinsed in running water for half an hour. The
next process is to remove the paste; which is done by wincing the goods
in a bran bath, lowered to 150°, during twenty minutes. They are then
winced for five minutes in a bath of water slightly sharpened with
vinegar. When well cleansed, they are ready for the madder bath. The
_lapis_ goods are finally cleared in a bran bath, by exposure on the
grass, and a soap boil.

The lazulite style is susceptible of many modifications.

8. _Deep blue ground_, with light blue, carmelite, and white figures.

  1. Print-on _the white_ reserve, No. 1.
  2. Dip in the strongest blue vat; rinse and dry.
  3. Ground-in with the block, the carmelite reserve (containing the
     mixed acetates of iron and alumina.)
  4. Ground-in the neutral reserve.
  5. Dip for the light blue; rinse.
  6. Dung, dye, and clear, as above.

By varying the proportions of the reserve mordants, and the dye stuffs,
as madder, quercitron, &c. a great variety of effects may be produced.

9. _Deep green ground_, with buff and white figures.

  1. Print-on the white reserve.
  2. Dip in the blue vat; rinse and dry.
  3. Pad in the buff liquor, as formerly prescribed.
  4. Ground in upon the buff spots, the discharge, No. 2. presently to
     be described.
  5. Wash away the paste in chalky water.
  6. Wince through a boiling alkaline lye, to raise the buff iron
     colour.

IV. _The Discharge style_; _first_, of simple discharges.

1. _Discharge for block printing._

  Take 1 gallon of lemon or lime-juice, of spec. grav. 1·09, in which
         dissolve
       1 pound of tartaric acid,
       1 pound of oxalic acid, and thicken the solution with
       4 pounds of pipe or china clay, and 2 pounds of pulverised gum;
         as soon as the gum is dissolved, the mixture must be put
         through a searce.

2. Another discharge is made of half the above acid strength.

3. A third with one half of the solid acids of the second.

  4. Take 1 gallon of water, in which dissolve with heat
          1 pound of cream of tartar adding, to facilitate the solution,
          1 pound of warm sulphuric acid of spec. grav. 1·7674; after 24
            hours mix
          4 libs. of pipe or China clay, and three libs. of gum with the
            decanted clear liquor.
          In some cases British gum is used alone, as a thickener.

5. Discharge for the cylinder machine.

  Take 1 gallon of lime juice, of spec. grav. 1·085; dissolve in it
       3 pounds of tartaric acid, and one pound of oxalic acid; thicken
         with
       6 pounds of gum senegal, or 5 pounds of British gum.

6., 7. A stronger and weaker discharge is made of the same materials;
and one is made without the tartaric acid.

_Second_; combination of discharges with mordants.

1. _Black, red, lilac, and white figures upon an olive ground._

The olive being given in a madder bath, and the ground well whitened
(see MADDER), the cloth is padded in a weak buff mordant; and upon the
parts that are to remain white, the weakest simple discharge No. 3. is
printed-on by the cylinder; (in some works the discharge paste is
applied and made dry before padding through the iron liquor;) the goods
are cleared of the paste in a tepid chalky water, then dyed in a
quercitron bath, containing a little glue, and cleared in a bran bath.

_Discharge mordants upon mordants_ may be regarded as a beautiful
modification of the preceding style. _Example._

_A violet ground or impression, with red and white._

1. Pad with an acetate of iron of 1·004; or print-on with the cylinder,
iron liquor of 1·027 thickened with British gum.

2. Print-on a red mordant, strongly acidulated with lime juice of 1·226.

3. Ground in the discharge No. 2.; dry.

4. Clear off the paste in chalky water.

5. Dung, madder, and brighten.

6. Ground-in the topical colours at pleasure.

V. China blues.

  Take 16 pounds of coarsely ground indigo, and
        4 pounds of sulphuret of arsenic; dissolve 22 pounds of sulphate
  of iron in 6 gallons of water; introduce these three matters into the
  indigo mill, and grind them for three days. If it be wished to have a
  thickened blue, this mixture must have pounded gum added to it, but if
  not, 5 gallons of water are added. This colour may be called blue No.
  1.

The following table exhibits the different gradations of China blue:--

  +--------+----------------------+----------------------+
  |Course. |Quantity by measure of|Quantity by measure of|
  |        |        No. 1.        |  water or mucilage.  |
  +--------+----------------------+----------------------+
  | No. 1  |           1          |           0          |
  |     2  |          11          |           1          |
  |     3  |          10          |           2          |
  |     4  |           8          |           4          |
  |     5  |           6          |           6          |
  |     6  |           4          |           8          |
  |     7  |           2          |          10          |
  |     8  |           2          |          12          |
  |     9  |           2          |          14          |
  |    10  |           2          |          16          |
  |    11  |           2          |          18          |
  |    12  |           2          |          20          |
  +--------+----------------------+----------------------+

I shall now give examples of working this style by the block and
cylinder:--

Impression of a single blue with small dots.

For the block, blue No. 5. thickened with starch.

For the cylinder, No. 4. thickened with gum.

_Impression of two different blues with the block._

First blue, No. 4. with starch.

Second blue, No. 9. with gum.

_Impression of three blues with the block._

First blue, No. 5. with starch.

Second blue, No. 7. with starch.

Third blue, No. 10. with gum.

After printing-on the blues, the pieces are hung up for two days in a
dry and airy place, but not too dry; then they are dipped as
follows:--Three vats are mounted, which may be distinguished by the
numbers, 1., 2., 3.--

No. 1. 300 pounds of lime to 1,800 gallons of water.

No. 2. Solution of sulphate of iron of spec. grav. 1·048.

No. 3. Solution of caustic soda of spec. grav. 1·055; made from soda
crystals, quicklime, and water, as usual.

The pieces being suspended on the frames, are to be dipped in the first
vat, and left in it ten minutes; then withdrawn, drained for five
minutes; next plunged into the second vat for ten minutes, and drained
also for five, &c. These operations will be most intelligible when put
into the form of a table:--

  Dip in the 1st vat.    During 10 minutes.    Drain during 5 minutes.
             2                  --                         --
             1                  --                         --
             2                  --                         --
             3                  --                         --
             2                  --                         --
             1                  --                         --
             2                  --                         --
             1                  --                         --
             2                  --                         --
             3                  --                         --

In the dipping of China blues, care should be taken to swing the frames
during the operation; and when the last dip is given, the piece is to be
plunged upon its frame into a fourth vat, containing dilute sulphuric
acid of spec. grav. 1·027. This immersion is for the purpose of removing
the oxide of iron, deposited upon the calico in the alternate passages
through the sulphate of iron and lime vats. They are then rinsed an hour
in running water, and finally brightened in the above dilute sulphuric
acid, slightly tepid. Sometimes they are subjected to a soap bath, at
the temperature of 120°. By the addition of nitrate of lead to the
indigo vat, the blue becomes more lively. Some use the roller dyeing
apparatus for running the pieces through the respective baths instead of
the square frames. (See WINCING.) But the frame-dip gives the most
evenly dyes, and preserves the vats in good condition for a much longer
time.

The various phenomena which occur in the dipping of China blues, are not
difficult of explanation with the lights of modern chemistry. We have,
on the one hand, indigo and sulphate of iron alternately applied to the
cloth; by dipping it into the lime, the blue is deoxidized, because a
film of the sulphate of iron is decomposed, and protoxide of iron comes
forth to seize the oxygen of the indigo, to make it yellow-green, and
soluble, at the same time, in lime-water. Then, it penetrates into the
heart of the fibres, and, on exposure to air, absorbs oxygen, so as to
become insoluble and fixed within their pores. On dipping the calico
into the second vat of sulphate of iron, a layer of oxide is formed upon
its whole surface, which oxide exercises an action only upon those parts
that are covered with indigo, and deoxidizes a portion of it; thus
rendering a second dose soluble by the intervention of the second dip in
the lime-bath. Hence we see that while these alternate transitions go
on, the same series of deoxidizement, solution, and re-oxidizement
recurs; causing a progressively increasing fixation of indigo within the
fibres of the cotton. A deposit of sulphate of lime and oxide of iron
necessarily falls upon the cloth, for which reason the frame should be
shaken in the lime water vat, to detach the sulphate; but, on the
contrary, it should be held motionless in the copperas bath, to favour
the deposition of as much protoxide upon it as possible. These
circumstances serve to account for the various accidents which sometimes
befall the China blue process. Thus the blues sometimes scale off, which
may proceed from one of two causes:--1. If the goods are too dry before
being dipped, the colour swells, and comes off in the vats, carrying
along with it more or less indigo. 2. If the quantity of sulphate of
lime formed upon the cloth be considerable, the crust will fall off, and
take with it more or less of the blue; whence arise inequalities in the
impression. The influence of temperature is important; when it falls too
low, the colours take a gray cast. In this case it should be raised with
steam.

VI. The decolouring or _enlevage_ style; not by the removal of the
mordant, but the destruction of the dye. The acid, which is here mixed
with the discharge paste, is intended to combine with the base of the
chloride, and set the chlorine free to act upon the colour. Among the
topical colours for this style are the following:--

  1. _Black._--Take one gallon of iron liquor of spec. grav. 1·086.
               One pound of starch; boil together, and while the paste
               is hot, dissolve in it
               One pound of tartaric acid in powder; and when cold, add
               Two pounds of Prussian blue, prepared with muriatic acid,
               see p. 226.
               Two ounces of lamp black, with four ounces of oil.
  2. _White discharge._--Take one gallon of water; in which dissolve
                         One pound and a half of oxalic acid,
                         Three pounds of tartaric acid; add
                         One gallon of lime juice of spec. grav. 1·22;
                         and thicken with
                         Twelve pounds of pipe clay, and six pounds of
                         gum.
  3. _Chrome-green discharge._--
                     Take one gallon of water, thicken with 18 ounces of
                     starch; boil and dissolve in the hot paste
                     Two pounds and a half of powdered nitrate of lead,
                     One pound and a half of tartaric acid,
                     Two pounds of Prussian blue, as above.
  4. _Blue discharge._--Take one gallon of water, thicken with
                        18 ounces of gum; while the boiled paste is hot,
                        dissolve in it
                        Two pounds of tartaric acid, and mix one pound
                        of Prussian blue.
  5. _Chrome-yellow discharge._--This is the same as the chrome-green
  given above, but without the Prussian blue.
  6. _A white discharge on a blue ground_, requires the above white
  discharge to be strengthened with 8 ounces of strong sulphuric acid,
  per gallon.
  7. _White discharge for Turkey red_ needs to be very strong.
     Take one gallon of lime juice of sp. grav. 1·086; dissolve in it
     Five pounds of tartaric acid; thicken with
     Eight pounds of pipe-clay, four pounds of gum; then dissolve in the
     mixture
     Three pounds of muriate of tin in crystals; and add, finally,
     Twenty-four ounces of sulphuric acid.
  8. _Yellow discharge for Turkey red._--
            Take one gallon of lime juice of spec. grav. 1·086; in which
            dissolve
            Four pounds of tartaric acid,
            Four pounds of nitrate of lead; thicken the solution with
            Six pounds of pipe-clay, and three pounds of gum.
  9. _For green discharge_, add to the preceding 24 ounces of Prussian
  blue, as above.

The decolouring or chlorine bath is usually formed of wood lined with
lead, and has an area of about 5 feet square, with a depth of 6 feet. A
square frame, mounted with a horizontal series of rollers at top and
bottom, may be let down by cords, at pleasure, into the cistern. The
pieces are introduced and guided in a serpentine path, round the upper
and lower rollers alternately, by a cord.

This bath is filled with a solution of chloride of lime, of the spec.
grav. 1·045, whose decolouring strength is 65° by Gay Lussac’s indigo
chlorometer. It ought to be made turbid by stirring before putting in
the goods, which should occupy three minutes in their passage. The piece
is drawn through by a pair of squeezer cylinders at the end of the
trough, opposite to that at which the piece enters. With black, white,
and blue impressions of all shades, the goods are floated in a stream of
water for an hour; then rinsed and dried. When there is yellow or green,
the pieces must be steeped in water, then merely washed by the wince,
and passed through solution of bichromate of potash, containing from 3
to 5 ounces of the salt per piece. Here the pieces are winced during 15
or 20 minutes, rinsed, and next passed through dilute muriatic acid to
clear the ground; then rinsed and dried.

_Discharge by the intervention of the chromic acid._

After having dipped the pieces to the desired shade, they are padded in
a solution of bichromate of potash; dried in the shade without heat; and
then printed with the following mordant:--

  Take 1 gallon of water; dissolve in it
  2 pounds of oxalic and 1 pound of tartaric acid; thicken with
  6 pounds of pipe clay, and 3 pounds of gum; lastly, add
  8 ounces of muriatic acid.

After the impression, the pieces are winced in chalky water, at 120° F.,
then washed, and passed through a dilute sulphuric acid.

M. Daniel Kœchlin, of Mulhausen, the author of this very ingenious
process, considers the action of the bichromate here as being analogous
to that of the alkaline chlorides. At the moment that the block applies
the preceding discharge to the bichromate dye, there is a sudden
decoloration, and a production of a peculiar odour.

The pieces padded with the bichromate must be dried at a moderate
temperature, and in the shade. Whenever watery solutions of chromate of
potash and tartaric acid are mixed, an effervescence takes place, during
which the mixture possesses the power of destroying vegetable colours.
This property lasts no longer than the effervescence.

VII. _Steam colours._--This style combines a degree of brilliancy with
solidity of colour, which can hardly be obtained in any other way,
except by the chintz dyes. The steam apparatus, employed for fixing
colours upon goods, may be distributed under five heads:--1. the column;
2. the lantern; 3. the cask; 4. the steam-chest; and, 5. the chamber.

The column is what is most generally used in this country. It is a
hollow cylinder of copper, from three to five inches in diameter, and
about 44 inches long, perforated over its whole surface with holes of
about one sixteenth of an inch, placed about a quarter of an inch
asunder. A circular plate, about 9 inches diameter, is soldered to the
lower end of the column, destined to prevent the coil of cloth from
sliding down off the cylinder. The lower end of the column terminates in
a pipe, mounted with a stop-cock for regulating the admission of steam
from the main steam-boiler of the factory. In some cases, the pipe fixed
to the lower surface of the disc is made tapering, and fits into a
conical socket, in a strong iron or copper box, fixed to a solid
pedestal; the steam pipe enters into one side of that box, and is
provided, of course, with a stop-cock. The condensed water of the column
falls down into that chest, and may be let off by a descending tube and
a stop-cock. In other forms of the column, the conical junction pipe is
at its top, and fits there into an inverted socket connected with a
steam chest, while the bottom has a very small tubular outlet, so that
the steam may be exposed to a certain pressure in the column, when it is
encased with cloth.

The pieces, after being printed with the topical colours presently to be
described, and dried, are lapped round this column, but not in immediate
contact with it; for the copper cylinder is first enveloped in a few
coils of blanket stuff; then with several coils of white calico; next
with the several pieces of the printed goods, stitched endwise; and
lastly, with an outward mantle of white calico. In the course of the
lapping and unlapping of such a length of webs, the cylinder is laid in
a horizontal frame, in which it is made to revolve. In the act of
steaming, however, it is fixed upright, by one of the methods above
described. The steaming lasts for 20 or 30 minutes, according to the
nature of the dyes; those which contain much solution of tin admit of
less steaming. Whenever the steam is shut off, the goods must be
immediately uncoiled, to prevent the chance of any aqueous condensation.
I was much surprised, at first, on finding the unrolled pieces to be
free from damp, and requiring only to be exposed for a few minutes in
the air, to appear perfectly dry. Were water condensed during the
process, it would be apt to make the colours run.

Steam colours are all topical, though, for many of them, the pieces are
previously padded with mordants of various kinds. Some manufacturers
run the goods before printing them through a weak solution of the
perchloride of tin, with the view of brightening all the colours
subsequently applied or raised upon them. I shall now illustrate steam
calico-printing by some examples, kindly furnished me by a practical
printer near Manchester, who conducts a great business with remarkable
success.

_Steam blue._--Prussiate of potash, tartaric acid, and a little
sulphuric acid, are dissolved in water, and thickened with starch; then
applied by the cylinder, dried at a moderate heat, and steamed for 25
minutes. They are rinsed and dried after the steaming. The tartaric
acid, at a high temperature, decomposes here a portion of the
ferrocyanic acid, and fixes the remaining ferrocyanate of iron (Prussian
blue) in the fibre of the cloth. The ground may have been previously
padded and dyed; the acids will remove the mordant from the points to
which the above paste has been applied, and bring out a bright blue upon
them.

_Steam purple._--This topical colour is made by digesting acetate of
alumina upon ground logwood with heat; straining, thickening with gum
senegal, and applying the paste by the cylinder machine.

_Steam pink._--A decoction of Brazil-wood with a small quantity of the
solution of muriate of tin, called, at Manchester, new tin crystals[15],
and a little nitrate of copper to assist in fixing the colour; properly
thickened, dried, and steamed for not more than 20 minutes, on account
of the corrosive action of muriate of tin when the heat is too strong.

  [15] This preparation is made by adding 3 libs. of sal ammoniac to 1
  gallon of solution of tin (_see_ SCARLET DYE, and TIN), evaporating,
  and crystallizing. The sal ammoniac seems to counteract the separation
  of the tin by peroxidizement.

_Cochineal pink._--Acetate of alumina is mixed with decoction of
cochineal, a little tartaric acid and solution of tin; then thickened
with starch, dried, and steamed.

_Steam brown._--A mixed infusion of logwood, cochineal, and Persian
berries, with cream of tartar, alum (or acetate of alumina), and a
little tartaric acid, thickened, dried, and steamed.

_Green, blue, chocolate, with white ground, by steam._--Prussiate of
potash and tartaric acid, thickened, for the blue; the same mixture with
berry-liquor and acetate of alumina, thickened, for the green; extract
of logwood with acetate of alumina and cream of tartar, thickened, for
the chocolate. These three topical colours are applied at once by the
three-colour cylinder machine; dried and steamed. Though greens are
fixed by the steam, their colour is much improved by passing the cloth
through solution of bichromate of potash.

In France, solution of tin is much used for steam colours.

VIII. _Spirit or Fancy colours._--These all owe their vivacity, as well
as the moderate degree of permanency they possess, to their tin mordant.
After printing-on the topical colour, the goods must be dried at a
gentle heat, and passed merely through the rinsing machine. Purple,
brown, or chocolate, red, green, yellow, blue, and white discharge; any
five of these are printed on at once by the five-colour cylinder
machine. See RINSING MACHINE.

_Chocolate_, is given by extract of Brazil-wood, extract of logwood,
nitromuriate of tin, with a little nitrate of copper; all mixed,
thickened, and merely printed-on.

_Red_, by extract of Brazil-wood and tin, with a little nitrate of
copper.

_Green_, by prussiate of potash, with muriate of tin and acetate of
lead, dissolved, thickened, and printed-on.

The goods after rinsing must be passed through solution of bichromate of
potash, to convert the Prussian blue colour into green, by the formation
of chrome yellow upon it.

_Blue._--Prussian blue ground up with solution (nitromuriate) of tin;
thickened, &c.

_Yellow._--Nitrate of lead dissolved in solution of tartaric acid,
thickened, tenderly dried, passed through the bichromate vat or padding
machine, washed and dried.

This yellow is pretty fast; though topical, it can hardly, therefore, be
called a fancy colour.

When _purple_ is to be inserted instead of the above blue, extract of
logwood with tin is used in the place of the Prussian blue. Tartaric
acid is a useful addition to tin in brightening fancy colours.

_Chocolate._--A good topical chocolate is made by digesting logwood with
liquid acetate of alumina, adding a little cream of tartar to the
infusion; thickening, applying by the cylinder, drying, washing, then
passing through solution of bichromate of potash, which serves to darken
and fix the colour.

I shall conclude my account of the printing of cotton goods with some
miscellaneous formulæ, which were given me by skilful calico-printers in
Lancashire.

_Prussian blue_ is prepared for topical printing by grinding it in a
handmill, like that for grinding pepper or coffee, and triturating the
powder with solution of muriate of tin.

_Green._--The deoxidized indigo vat liquor is mixed with a little
pearlash, and thickened with gum. This is applied by the cylinder or
block to goods previously padded with nitrate of lead; the goods, after
being dried, are passed through milky lime-water, rinsed, and then
winced or padded through the bichromate of potash bath.

_Another green._--Nitrate of lead, prussiate of potash, and tartaric
acid, dissolved, and mixed with a little sulphate, nitrate, and muriate
of iron; this mixture is either thickened for cylinder printing, or used
in its liquid state in the padding trough. The goods subjected to one of
these two processes are dried, padded in weak solution of carbonate of
potash, which serves to precipitate the oxide of lead from the nitrate;
they are finally padded with bichromate of potash, which induces a
yellow upon the blue, constituting a green colour of any desired tint,
according to the proportion of the materials.

_Chocolate and black, with white discharge; a fast colour._--The cloth
is padded with acetate of alumina, and dried in the hot flue; it is then
passed through a two-colour machine, the one cylinder of which prints-on
lime-juice discharge, thickened with gum senegal; the other a black
topical dye (made with logwood extract and iron liquor). The cloths are
now hung up to be aired during a week, after which they are dunged, and
dyed up with madder, fustic, and quercitron bark, heated with steam in
the bath.

_Blue, white, and olive or chocolate._--1. Pad with the aluminous
mordant; 2. Apply thickened lemon juice for discharge by the cylinder;
3. Dung the goods after they are thoroughly dried; 4. Pass them through
the bath of madder, fustic, and quercitron, which dye a brown ground,
and leave the discharge points white; then print-on a reserve paste of
China clay and gum with sulphate of copper; dry, dip in the blue vat,
which will communicate an olive tint to the brown ground; or a
chocolate, if madder alone had been used.

When a black ground is desired, with white figures, the acid discharge
paste should be printed-on by the cylinder, and dried before the piece
is padded in the iron liquor. By following this plan the whites are much
purer than when the iron is first applied.

_Green, black, white._--The black is first printed-on by a mixture of
iron liquor, and infusion (not decoction) of logwood; then resist or
reserve paste is applied by the block, and dried; after which the goods
are blued in the indigo vat, rinsed, dried, passed through solution of
acetate of lead; next, through milky lime water; lastly, through a very
strong solution of bichromate of potash.

_Turkey red, black, yellow._--Upon Turkey red cloth, print with a strong
solution of tartaric acid, mixed with solution of nitrate of lead,
thickened with gum; dry. The cloth is now passed through the chloride of
lime bath, washed, and chromed. Lastly, the black is printed-on by the
block as above, with iron liquor and logwood.

_Black ground dotted white, with red or pink and black figures._--1.
Print-on the lime juice discharge-paste by the cylinder; dry; 2. Then
pad with iron liquor, containing a little acetate of alumina, and hang
up the goods for a few days to fix the iron; 3. Dye in a logwood bath to
which a little madder has been added; clear with bran. The red or pink
is now put in by the block, with a mixture of extract of Brazil-wood,
nitromuriate of tin, and nitrate of copper, as prescribed in a preceding
formula.

_Orange or brown; black; white; pink._--The black is topical, as above;
it is printed-on, as also the lemon-juice discharge and red mordant,
with muriate of tin (both thickened), by the three-colour machine. Then,
after drying the cloth, a single-cylinder machine is made to apply in
diagonal lines to it a mixture of acetate of iron and alumina. The
cloth, being dried and dunged, is next dyed in a bath of quercitron,
madder, and fustic.

Here the orange is the result of the mordant of tin and alumina; the
brown, of the alumina and iron; white, of the citric acid discharge. The
tin mordant, wherever it has been applied, resists the weaker mordant
impressed in the diagonal lines. The pink is blocked-on at the end.

_Orange brown, or aventurine; black and white._--The topical black (as
above), and discharge lemon juice, are printed-on by the two-colour
machine; then the cloth is subjected to the diagonal line cylinder,
supplied with the alumino-iron mordant. The cloth is dried, dunged, and
dyed in a bath of bark, madder, and fustic.

The manganese or _solitaire_ ground admits of a great variety of figures
being easily brought upon it, because almost every acidulous mordant
will dissolve the oxide of manganese from the spot to which it is
applied, and insert its own base in its place; and of course, by dyeing
such mordanted goods in various baths, any variety of coloured designs
may be produced. Thus, if the paste of nitrate of lead and tartaric acid
solution be applied, and the goods after drying be passed first through
lime water, and then through a chrome bath, bright yellow spots will be
made to appear upon the bronze ground.

_Manganese bronze, buff and green; all metallic colours._--Pad-on the
manganese solution, and dry; apply the aceto-sulphate of iron, of spec.
grav. 1·02, and Scheele’s green (both properly thickened), by the
two-colour machine. The goods are next to be dried, and padded through a
cold caustic lye of spec. grav. 1·086. They are then rinsed, and passed
through a weak solution of chloride of lime, to raise the bronze, again
rinsed, and passed through a solution of arsenious acid to raise the
green.

Scheele’s green for the calico-printer is made as follows:--

Take 1 gallon of water, in which dissolve with heat,

5 pounds of sulphate of copper, and 1 pound of verdigris. When the two
salts are dissolved, remove the kettle from the fire, and put into it 1
quart of solution of nitrate of copper, and 5 pounds of acetate of lead.
Stir the mixture to facilitate the decomposition, and allow the pigment
to subside.

It must be thickened with 2-1/2 libs. of gum per gallon, for pencilling;
or 12 oz. of starch for the block. The goods printed with this paste are
to be winced through a caustic lye, till a fine sky-blue be produced;
then washed well and rinsed. They are now to be passed through water,
containing from half an ounce to an ounce of white arsenic per piece; 4
turns are sufficient; if it be too long immersed, it will take a yellow
tint.

Catechu has been considerably employed by calico-printers of late years,
as it affords a fine permanent substantive brown, of the shade called
_carmelite_ by the French. The following formula will exemplify its mode
of application:--

Take 1 gallon of water;

1 pound of catechu in fine powder; reduce by boiling to half a gallon,
pass the decoction through a fine sieve, and dissolve in it 4 ounces of
verdigris; allow it then to cool, and thicken the solution with 5 ounces
of starch; while the paste is hot, dissolve in it 5 ounces of pulverized
muriate of ammonia.

Print-on this paste, dry, and wash. It is a fast colour.

I shall subjoin the prescriptions for two fancy cochineal printing
colours.

_Amaranth by cochineal._--Pad the pieces in the aluminous mordant of
spec. grav. 1·027, page 224.

Dry in the hot flue; and after hanging up the goods during 3 days, wince
well through chalky water, and then dye, as follows:--

For each piece of 28 or 30 yards, 8 ounces of cochineal are to be made
into a decoction of 2 gallons in bulk, which is to be poured into a
kettle with a decoction of 3 ounces of galls, and with 2 ounces of bran.
The pieces are to be entered, and winced as in the madder bath, during
two hours and a half; then washed in the dash wheel. On mixing with the
amaranth bath a certain quantity of logwood, very beautiful lilacs and
violets may be obtained.

_Mixture of quercitron and cochineal._--Pad in the aluminous mordant,
and dye with 2 libs. of quercitron, and 4 ounces of cochineal, when a
capuchin colour will be obtained. If we pad with the following mordant;
viz. 1 gallon of acetate of alumina of 1·056 spec. grav., and 1 of iron
liquor of 1·02 spec. grav., and dye with 1 pound of quercitron, and 1
ounce of cochineal, we shall obtain a shade like boot-tops, of extreme
vivacity.

Two ounces of cochineal will print a long piece of calico with rich pink
figures, having acetate of alumina for a mordant. As the ground is
hardly tinged by the dye, it neither needs nor admits of much clearing.

I have already mentioned that goods are sometimes padded with solution
of perchloride of tin before printing-on them the steam colours, whereby
they acquire both permanence and vivacity. I have also stated that the
salts of tin at a high temperature are apt to corrode the fibre of the
stuff, and therefore must be used with discretion. This danger is
greatly lessened by adding to the perchloride of tin a sufficient
quantity of caustic potash lye to form a stannate of potash. The goods
are padded through this substance, diluted with water, dried with a
moderate heat, and then immersed in very dilute sulphuric acid, which
saturates the potash, and precipitates the tin oxide within the pores of
the cloth. Calico thus prepared affords brilliant and permanent colours
by the steam process, above described.

_Printing of silks or woollen stuffs, such as merinoes and mousselin de
laine, as also of mixed stuffs of silk and wool, such as chalys._--All
these prints are applied, not by the cylinder but the block, and are
fixed by the application of steam in one of four ways; 1. By the
_lanthorn_; 2. By the _cask_; 3. By the _chest_; or 4. By the _chamber_.

[Illustration: 238]

1. _By the lanthorn._--In this mode of exposure to steam, the goods are
stretched upon a frame; and therefore the apparatus may be described
under two heads; the lanthorn and the frame. The former is made of
copper, in the shape of a box A B C D E, _fig._ 238., open below, and
with a sloping roof above, to facilitate the trickling down of the water
condensed upon the walls. The sides B C D E are 4-1/2 feet high, 6 feet
long, and 4 feet wide. The distance of the point A from the line E B is
2 feet. At F is a brass socket, which may be stopped with a cork; and
there is a similar one at the other side. This kind of penthouse may be
raised by means of a pully with cords fixed to the four angles of the
roof E B; and it rests upon the table G H, a little larger than the area
of the box, which stands upon the four feet I K. Round the borders of
the table there is a triangular groove _a b_, for receiving the lower
edges of the box, and it is stuffed steam-tight with lists of cloth.
Through the centre of the table, the two-inch steam pipe M passes; it
is surmounted with an hemispherical rose pierced with numerous holes for
the equal distribution of the steam. Right above it, a disc N is placed
upon four feet. The tube L communicates with a box P, which has a syphon
Q to let off the condensed water. At the upper part of this box the tube
L terminates which brings the steam. The little table G H slopes towards
the part G, where the syphon R is placed for drawing off the water.

The _frame_ has such dimensions, that it may stand in the four corners
of the table at S S, as pointed out by the dotted lines. The second part
embraces an open square frame, which is formed by spars of wood 2 inches
square, mortised together; and is 3 feet 8 inches wide, 5 feet 8 inches
long, and 4 feet 3 inches high; it is strengthened with cross bars. Upon
the two sides of its breadth, two rows of round brass hooks are placed,
about half an inch apart; they are soldered to a copper plate fixed to
uprights by means of screws.

Before hanging up the goods, a piece of cloth 3 feet 8 inches long, and
4 feet wide, is placed upon the row of hooks; and 3 feet of it are left
hanging out.

One foot within, the hooks pass through the cloth. A similar one is
fitted to the other side. This cloth is intended to cover the goods hung
upon the hooks; and it is kept straight by resting upon strings. The
pieces are attached zig-zag from one hook to another. When the frame is
filled, the bag is put within the cloths; it has the same rectangular
shape as the frame. The pieces are in this way all encased in the cloth;
a bit of it being also put beneath to prevent moisture affecting that
part.

When shawls are framed, they are attached with pins; and if they be too
large, they are doubled back to back, with the fringes at top.

These arrangements being made, the frame is set upon the table, the
penthouse is placed over it, and the steam is admitted during from 35 to
45 minutes, according to circumstances. The orifice F is opened at first
to let the air escape, and when it begins to discharge steam it is
stopped. The frame is taken out at the proper time, the bag is removed,
the cloths are lifted off, and the goods are spread out for airing.
Three frames and six bags are required for a constant succession of
work. The above apparatus is particularly suitable for silks.

[Illustration: 239 240]

2. _The drum._--This is the most simple mode of steaming. The apparatus
is a drum of white wood, 2 inches thick, _fig._ 239.; the bottom is
pierced with a hole which admits the steam-pipe F, terminating in a
perforated rose. Four inches from the bottom there is a canvass
partition E, intended to stop any drops of water projected from the tube
F, and also to separate the condensed water from the body of the
apparatus. The drum is covered in by a wooden head H, under which the
goods are placed. It is made fast either by bolts, or by hooks, G G,
thus [S], to which weighted cords are hung. The frame 1, _fig._ 240.
rests upon a hoop, _a a_, a few inches from the edge. The goods are hung
upon the frame in the ordinary way, and then wrapped round with flannel.
The frame is studded with pin points, like that of the indigo vat, fixed
about 5 inches asunder. From 20 to 30 minutes suffice for one steaming
operation. The upper part of the frame must be covered also with
flannels to prevent the deposition of moisture upon it. At the bottom of
the drum there is a stopcock to let off the condensed water. According
to the size of the figure, which is 3 feet 2 inches, 50 yards may be
hung up single; but they may be doubled on occasion.

[Illustration: 241 242 243 244]

3. _The box._--This steaming apparatus is convenient from the large
quantity of goods admissible at a time: it answers best for woollen
stuffs. From 12 to 16 pieces, of 36 yards each, may be operated upon at
once; and from 240 to 260 shawls. It is formed of a deal box, A B C D,
_fig._ 241., 4 feet wide, 6 long, and 3 high; the wood being 4 inches
thick. It is closed by a cover of the same substance, I, which is made
steam-tight at the edges by a list of felt. The lid is fastened down by
5 cross bars of iron, _a a a a a_, which are secured by screws, _c c c c
c_, _fig._ 242. The ends of these cross bars are let into the notches,
_b b b b b_, on the edge of the box. The safety valve M, _fig._ 241., is
placed upon the lid. For taking off the lid, there are rings at the
four corners, _d d d d_, bearing cords, F F F F. These join at the
centre into one, which passes over a pulley. Eight inches from the
bottom of the box there is a horizontal canvass partition, beneath which
the steam is discharged from the pipe L, _fig._ 243. There are two
ledges, E F G H, at the sides for receiving the bobbins. The tube L runs
round the box, as shown by the letters _d a e b_: the end _d_ is shut;
but the side and top are perforated with many holes in the direction
towards the centre of the box. _Fig._ 244. shows the arrangement of the
lower set of bobbins: that of the upper set is shown by the dotted
lines: it is seen to be in an alternate position, one lying between two
others. They are formed of pieces of deal 4 inches broad, 1 inch thick,
and of a length equal to the width of the box. They are first wrapped
round with 5 or 6 turns of doubled flannel or calico: the piece of goods
is laid over it upon a table, and then wrapped round. At the end of the
piece, several folds of the covering must be put, as, also, a roll of
flannel. The two ends must be slightly tied with packthread. When these
flat bobbins are arranged in the box, the steam is let on them, and
continued about 45 minutes: it is then shut off, the lid is removed, and
the pieces are unrolled.

[Illustration: 245]

4. _The chamber._--The interior height of the chamber, A B C D, _fig._
245., is 9 feet, the length 12 feet, and the breadth 9 feet. The steam
is introduced into it by two pipes, _a b c_, _d e f_. Their two ends, _d
c_, are shut; but their sides are all along perforated with small holes.
The frames E F G H, E F G H, are moveable, and run upon rollers: they
are taken out by front doors, which are made of strong planks, shut by
sliding in slots, and are secured by strong iron bars and pressure
screws. The cross rods, E F G H, are provided with hooks for hanging up
the pieces. There is a safety-valve in the top of this large chamber.
The dimensions of the frame are 10 feet long, 3 feet wide, and 7 high.
Three feet and a half from the upper part of the frame, a row of hooks
is fixed for hanging on a double row of pieces, as shown in the figure.
Over the frame, woollen blankets are laid to protect it from drops of
water that might fall from the roof of the chamber. When the hooks are
two thirds of an inch apart, 24 pieces, of 28 yards each, may be
suspended at once. The period of steaming is from 45 to 60 minutes.

Muslins and silks do not require so high a temperature as woollen goods.
When the stuffs are padded with colour, like merinos and chalys, they
must not be folded together, for fear of stains, which are sometimes
occasioned by the column in steam calico-printing, where the end which
receives the first impression of the steam is seldom of the same shade
as the rest of the roll of goods. The duration of the steaming depends
upon the quantity of acid in the mordant, and of saline solution in the
topical colour; the more of which are present, the shorter should be the
steaming period. A dry vapour is requisite in all cases; for when it
becomes moist, from a feeble supply or external condensation, the goods
become streaky or stained by the spreading of the colours.

1. _Black figures_ are given by decoction of logwood thickened with
starch, to which a little oxalic acid is added while hot, and, after it
is cold, neutralised solution of nitrate of iron.

2. _Dark blue for a ground._--Decoction of logwood, and archil thickened
with starch; to which, while the paste is hot, a little soluble Prussian
blue is added; and, when it is cold, neutralised nitrate of iron; see
_supra._

3. _Deep poppy or ponceau colour._--Cochineal boiled in starch water,
with oxalic acid (or tartaric), and perchloride of tin.

4. _Rose._--Cochineal infusion; oxalic acid; perchloride of tin;
thickened with gum.

5. _Dark amaranth._--Decoctions of archil and cochineal, thickened with
starch: to the paste, alum and perchloride of tin are added.

6. _Capuchin colour._--Quercitron and cochineal thickened with starch;
to the paste add oxalic acid, and perchloride of tin.

7. _Annotto orange._--Dissolve the annotto in soda lye, of spec. grav.
1·07, at a boiling heat; add aluminate of soda, and thicken with gum.

8. _Golden yellow._--Decoction of Persian berries thickened with starch;
to which some alum and muriate of tin are added, with a little
perchloride of tin and oxalic acid.

9. _Lemon yellow._--Persian berries; starch; alum.

10. An ammoniacal solution of cochineal is used for making many violet
and mallow colours. It is prepared by infusing cochineal in water of
ammonia for 24 hours; then diluting with water, heating to ebullition,
and straining.

11. _Fine violet_ is given by ammoniacal cochineal, with alum and oxalic
acid; to which a little aceto-sulphate of indigo is added, and gum for
thickening. The following blue may be used instead of the solution of
indigo. The _mallow_ tint is given by adding a little perchloride of tin
to the above formula, and leaving out the blue.

12. _Dark blue._--Soluble Prussian blue; tartaric acid; alum; thicken
with gum.

13. _Emerald green._--One quart of decoction, equivalent to 1 pound of
Persian berries; 1 quart of infusion of quercitron, of spec. grav.
1·027; in which dissolve 12 ounces of alum in powder; and add 6 ounces
of the following blue bath for greens; thicken with 20 ounces of gum.

14. Blue bath for greens. Half a gallon of water at 140° F., 1 pound of
soluble Prussian blue, 3 ounces of tartaric acid, and 2 ounces of alum.

I. _Printing of Silks._--1. _Of the madder style._ This is one of the
most difficult to execute, requiring both much skill and experience. The
first step is the removal of the gum. A copper being nearly filled with
water, the pieces, tied up in a linen bag, are put into it, with a
quarter of a pound of soap for every pound of silk, and are boiled for 3
hours. If the silk be Indian, half an ounce of soda crystals must be
added. When the goods are taken out, they are rinsed in the river, then
passed through water at 140° F., holding 8 ounces of crystallised soda
in solution, as a scourer. They are next rinsed in cold water, and
steeped in water very faintly acidulated with sulphuric acid, during 4
hours, then rinsed, and dried.

_Preparation of Mordants._--1 gallon of boiling water; 2 pounds of alum;
dissolve:

1 pound of acetate of lead; 4 ounces of sal-ammoniac; 1 of chalk; mix
well together; after decomposition and subsidence, draw off clear.

1. _Red._--1 gallon of the above mordant, thickened with 14 ounces of
starch, and tinged with decoction of Brazil wood. If dark red be wanted,
dissolve, in a gallon of the above red, 4 ounces of sulphate of copper.

2. _Black._--1 gallon of iron liquor, of 1·056 spec. grav.; thicken with
14 ounces of starch; and dissolve in the hot paste 2 ounces of sulphate
of copper.

  3. _Violet._ Take 1 gallon of iron liquor of 1·04 spec. grav.;
               2 ounces of cream of tartar; 2 ounces of nitre; 2 ounces
                 of copperas;
               1 ounce of alum: dissolve, and mix the solution with
               1 gallon of gum water, containing 6 libs. of gum.

  4. _Puce._ Half a gallon of red mordant; half a gallon of iron liquor
               of 1·07;
             7 ounces of starch for thickening colour with logwood.

_Manipulation of the above colours._--Print-on the black, then the puce,
next the violet, and, lastly the red. Dry in the hot flue, and, 48 hours
after the impression, wash away the paste. The copper employed for
dyeing is of a square form: a boil is given with bran, at the rate of 4
libs. per piece of the _foulards_: cold water is added to lower the
temperature to 130° F. The pieces must be entered with the printed
surface undermost, and winced for half an hour, taking care to keep them
expanded and well covered with the liquor: they are then taken out and
rinsed. When grounds are to be made on the foulards, 2 ounces of sumach
must be added per piece.

_Maddering._--Suppose 48 pieces are to be grounded with madder. 12
pounds of madder must be put into the copper, 1 pound of sumach, and 6
pounds of bran; the bath must be tepid when the pieces are entered: it
must be heated to 104° F. in 20 minutes, and to the boiling point in an
hour and a half. The goods must be briskly winced all the time, and
finally turned out into cold water.

When they come out of the madder bath they are much loaded with colour.
They are cleared by a boil of half an hour in bran, then turned out into
cold water, and rinsed. A copper must be now mounted with 3 pounds of
soap, 1 ounce of solution of tin, and 2 pailsful of bran, in which the
goods are to be boiled for half an hour, then rinsed, and passed through
a very dilute sulphuric acid bath. Then rinse, and dry. By following
this process a light salmon ground is obtained.

II. _Steam colours upon silk._--The same plan of operations may be
adopted here as is described for calico-printing; the main difference
being in the method of mordanting the stuffs. After boiling in soap
water, in the proportion of 4 ounces per pound of silk, the goods are
washed in cold water, and then in hot water at 140°; they are next
rinsed, passed through weak sulphuric acid, rinsed, squeezed between
rollers, and afterwards steeped in a bath containing 8 ounces of alum
per gallon, where they remain for four hours, with occasionally wincing.
They are now rinsed, and dried. The subsequent treatment resembles that
of steam-colour printed cottons.

  _Black._--Take a gallon of decoction, made with 4 libs. of logwood,
              with which
            14 ounces of starch are to be combined: mix in
            2 ounces of powdered nut-galls: boil, and pour the colour
              into a pipkin containing
            2 ounces of tartaric acid; 2 ounces of oxalic, both in
              powder, and
            2 ounces of olive oil. Stir the colour till it is cold, and
              add
            8 ounces of nitrate of iron, and 4 ounces of nitrate of
              copper.

The red, violet, lilac, yellow colours, &c. are the same as for steam
colours upon cotton. Topical colours are also applied without mordanting
the silk beforehand. In this case a little muriate of tin is introduced.
Thus, for

  _Yellow._--Take 1 gallon of a decoction, made with 4 libs. of Persian
             berries: dissolve in it 8 ounces of salt of tin (muriate),
             and 4 ounces of the nitro-muriatic solution of tin. Thicken
             with 2 pounds of gum.

[Illustration: 246 247]

_Printing of foulard pieces._ The tables which serve for the impression
of silk goods are so constructed as to receive them in their full
breadth. Towards the part between the colour or sieve tub and the table,
the roller is mounted upon which the piece is wound. This roller, A B,
_fig._ 246., has a groove, C, cut out parallel to its axis. Into this a
bar is pressed, which fixes the end of the piece. The head, B, of the
roller is pierced with several holes, in which an iron pin passes for
stopping its rotation at any point, as is shown at B. At the other end
of the table there is placed a comb, _fig._ 247., which is supported by
pivots A B at its ends. The teeth of the comb are on a level with the
cloth.

The piece is arranged for printing as follows:--It is unwound, and its
end is brought upon the teeth of the comb, and made to pass into them by
slight taps with a brush. It is now stretched, by turning round the
roller, and fixing it by the pin-handle. After tracing the outline, the
printing blocks are applied. Care should be taken, in the course of
printing, always to fix the teeth of the comb in the middle line between
two handkerchiefs. The operation of grounding-in is much facilitated by
this plan of extension.

The pieces are washed in running water, and must be rapidly dried. The
subsequent dressing is given by gum tragacanth: they are dried upon a
stretching frame, and then folded up for the market.

III. _Mandarining of silk stuffs and chalys._--This style of printing
depends upon the property which nitric acid possesses of giving to silk
and woollen stuffs a yellow colour.

The first step is the scouring with a soap boil, as already described.

The designs are printed-on as also above described.

[Illustration: 248]

The swimming or colour-tub is usually double, and serves for two tables;
instead of being placed, therefore, at the end of the table, it is put
between two, and, consequently, behind the printer. It is formed of a
copper chest, _fig._ 248., A B C D, in which steam may circulate,
introduced by the pipe I; the excess being allowed to escape by the tube
J, as also the water of condensation. The frame is placed in the hollow
box K K. Between two such frames there is a plate of copper, L, which
closes the box; it serves for laying the plates in order to keep them
hot. At E and H are prolongations of the box, in which are set the
vessels F G for holding the reserve paste.

_Preparation of the reserve or resist paste._--Melt in a kettle 2-1/2
libs. of rosin; 1 lib. of suet: mix well, and put it into the basins F
G. By means of steam the reserve is kept melted, as well as the false
colour upon which the sieve floats. The piece of silk being laid upon
the table, and the reserve spread upon the frame, the printer heats his
block, which should be mounted with lead, if the pattern will permit,
upon the little table L. He takes up the colour from the frame, and
transfers it instantly to the piece. He must strike the block lightly,
and then lift it, lest, by its cooling, it might stick to the silk. When
the table pattern is completed, he dusts it over with sand, and proceeds
to another portion of the silk. The piece must not be taken out of the
stretch till it is quite dry, which requires usually 6 hours. Let us
consider first the most common case, that of a white upon an orange
ground. We shall afterwards describe the other styles, which may be
obtained by this process. The piece, being printed and dry, must next be
subjected to the _mandarining_ operation.

[Illustration: 249 250]

The apparatus here employed consists of a sandstone trough A B C D,
_fig._ 249. Upon the two sides, A C, B D, of this trough are fixed two
wooden planks, pierced with a hole an inch from the bottom to receive
the roller E, under which the piece passes. In this trough the acid
mixture is put. That trough is put into a wooden or copper trough, F G H
I. Into the latter, water is put, which is heated by means of steam, or
a convenient furnace. Before and behind are placed two winces, or reels,
K L: one serves to guide the piece in entering into the trough, and the
other in its leaving it. The piece falls immediately into a stream of
cold water, or, failing that, into a large back, containing a mixture of
chalk and water. The two winces are moved by handles: the velocity is
proportioned to the action of the acid. The wince L ought to be higher
than K, to allow the acid to drain off. _Fig._ 250. shows a section of
the apparatus.

The temperature of the acid mixture ought to be maintained between 95°
and 100° F.; for if it be raised higher, the resist would run the risk
of melting, and the impression would become irregular and blotty.

The proportions of the acid mixture are the following:--1 gallon of
water; and 1 gallon of nitric acid, of spec. grav. 1·288, which may be
increased with the strength of the silk. It should be a little weaker
for chalys. For the strong greens it may be 2 measures of acid of 1·288
to 1 measure of water. The duration of the passage through the acid
should be 1 minute at most.

_Mixture of orange colour, and clearing away of the resist._--The goods,
on coming out of the mandarining apparatus, are rinsed in running water;
then boiled in soap water, quickened with a little soda, at the rate of
2 libs. of the former and 4 oz. of the latter for a piece of 30 yards.
They must be worked by the wince for half an hour. They are now rinsed
in cold water, then passed through hot, again rinsed, and dried. I shall
give some examples of the mode of manufacture, which is undoubtedly one
of the most curious applications of chemical ingenuity.

1. _Orange ground with white figures._

(1.) Print-on the fat reserve; (2.) mandarine; (3.) brighten the orange,
and clear.

2. _Orange ground, with blue figures._

(1.) Dip in the indigo vat as for calico; (2.) print-on the fat resist
to preserve the blue; (3.) mandarine; 4. clear, and brighten the orange
by the boil.

3. _Orange ground, with blue and white figures._

(1.) Print-on the resist to preserve the white; (2.) dip in the vat,
rinse, and dry; (3.) ground-in the fat resist to preserve the blue; (4.)
mandarine; (5.) cleanse, and brighten.

4. _Full green ground, and white figures._

(1.) Print-on the resist; (2.) mandarine, and rinse without drying; (3.)
dip in the blue vat; (4.) cleanse, and brighten.

5. _Full green ground, and blue figures._

(1.) Dip a pale blue, rinse, and dry; (2.) print-on the fat resist; (3.)
mandarine, wash and dry; (4.) dip full blue; (5.) clean, and brighten.

6. _Full green ground, with white and blue figures._

(1.) Print-on the resist; (2.) dip a pale blue, and dry; (3.) ground-in
the fat resist; (4.) mandarine and rinse; (5.) dip a full blue; (6.)
clean, and brighten.

7. _Full green ground, with white, blue, and orange figures._

(1.) Print-on the fat reserve; (2.) dip a pale blue, and dry; (3.)
ground-in the reserve; (4.) mandarine, rinse, and dry; (5.) ground-in
the reserve; (6.) dip a full blue; (7.) clean, and brighten.

If blue grounds with white figures be wanted, the resist must be
applied, and then the goods must be dipped in the blue vat: the resist
is afterwards removed by a boil in soap-water.

The above processes are applicable to chalys.

The property which nitric acid possesses of staining animal matters
yellow, such as the skin, wool, and silk, is here applied to a very
elegant purpose.

_Of the bronze or solitaire style by mandarining._--The mandarining
mixture, is

1 gallon of nitric acid, of 1·17 spec. grav.; mixed with 3 pints of
solution of nitrate of iron, of spec. grav. 1·65. If the quantity of
nitrate of iron be increased, a darker tint will be obtained. The
temperature of the mixture should be 94° F. The pieces, after
mandarining, are let fall into water, and steeped for an hour.

In order to raise the bronze, and clear away the fat resist, the goods
must be boiled in a bath of soap and soda, as described for orange.

1. _Bronze ground, with white figures._

(1.) Print on the fat resist; (2.) dip in the blue vat, and dry; (3.)
pad in a decoction of logwood, of 4 libs. per gallon; dry, taking care
to turn over the selvages; (4.) mandarine, and steep in water for an
hour; (5.) cleanse, and pass through soap.

2. _Bronze ground, with blue figures._

(1.) Dip in the blue vat, and dry; (2.) print-on the fat resist; (3.)
pad in the above decoction of logwood, and dry; (4.) mandarine, and
steep an hour; (5.) cleanse, and brighten.

3. _Bronze ground, with white and blue._

(1.) Print-on the fat resist; (2.) dip in the blue vat, and dry; (3.)
ground-in the fat resist; (4.) pad in the logwood liquor, and dry; (5.)
mandarine, and steep for an hour; (6.) cleanse, and give the brightening
boil with soap.

This style of manufacture may be executed on chalys; and is capable of
producing beautiful effects, which will in vain be sought for by other
means.

With silks, advantage may be derived from various metallic solutions
which possess the property of staining animal substances; among which
are nitrate of silver, nitrate of mercury, and muriate of iron. The
solutions of these salts may be thickened with gum, and printed-on.

_An orange upon an indigo vat ground._--After the blue ground has been
dyed, orange figures may be produced by printing-on the following
discharge paste:--

1 gallon of water, made into a paste with 1 pound of starch: when cold,
add to it from 16 to 24 ounces of nitric acid, of spec. grav. 1·288.
After fixing the colour by steam, the orange is brightened with a soap
boil.

_An orange upon a Prussian-blue ground._--The dye is first given by
Prussian blue in the ordinary way, and then the following discharge is
printed-on:--

A caustic lye being prepared, of 1·086 specific gravity, dissolve in a
gallon of it 2 pounds of annotto, and thicken with 3 pounds and a
quarter of gum. Two days after the impression of this paste, pass the
goods through steam, and wash them in running water. With these two
designs, the logwood and gall black, formerly described, may be
associated, to produce a rich effect.

To the preceding practical instructions for printing calicoes, silks,
woollens, and mixed fabrics, made of the two latter, a few annotations
may be added.

When an uniform colour is to be applied to both sides of the cloth, the
padding process is employed; but, when only one side is to be thus
coloured, diagonal lines are cut very closely to each other upon the
cylinder, which transfer so much colour from the trough to the cloth
passed under it as to make the surface appear uniformly stained. This
process is called _mattage_ by the French. Mordants or topical dyes, to
be applied in this way, should not be much thickened.

The _doubler_ is the piece of felt or blanket stuff placed between the
cloth to be printed, and the block printing table, or the cylinders. It
should be kept very clean; because, were it soiled with acetate of iron,
it would spoil all the light shades made with acetate of alumina.

Filters for the colour shop of a print house are best made of wool,
formed into a substantial conical cap by felting. A filter ought to be
set apart for each different dye stuff.

When the goods after dyeing are washed, by being held by the selvage,
dipped, and shaken in a stream of water, the process is called _giving a
list_ by the French (_donner une lisière_). The piece is transferred
alternately from one hand to another.

_Stains._ When we observe stains produced by mordants, upon spots where
no colour is to come, we must, before dunging the goods, apply a little
of the lime juice, or tartaro-oxalic acid discharge paste, to the place.
If, on the contrary, the stains are not perceived till after the
maddering, we must then apply to it first a strong solution of chloride
of lime with a pencil, next a solution of oxalic acid mixed with a
little muriatic with another pencil, and immediately afterwards wash
with water. Every madder stain will be effaced by this means.

Rust stains are removable by a mixture of oxalic and muriatic acids.

Indigo stains by the combined action of chloride of lime and muriatic
acid.

Topical yellow stains, or yellow dyes, by the same combination.

Metallic greens and Scheele’s green by the acid alone.

Chrome green, and Prussian blue. The blue may be taken out by a caustic
alkali; after which the goods must be washed: the residuary rust stain
may be removed by the mixture of oxalic and muriatic acids. The above
methods refer to cotton and linen. The stains on silk and woollen stuffs
should be removed before fixing the colours by the soap boil; which may
generally be done by scratching with the finger, with the aid of a
little water.

For a direct calico green, see oxide of CHROME.

Mr. Hudson, of Gale, near Rochdale, obtained a patent, in December,
1834, for a mechanism which furnishes a continual and regular supply of
colour to the sieve or tear (_tiré_, Fr.) into which the printer has to
dip his block, for the purpose of receiving the colour about to be
transferred to the fabric in the operations of printing calicoes or
paper hangings. The contrivance consists in a travelling endless web,
moved by power, which, by passing progressively from the colour vat over
the diaphragm, brings forward continuously an equable supply of the
coloured paste for the workman’s block.

[Illustration: 251]

_Fig._ 251. represents the construction of this ingenious apparatus,
shown partly in section. _a a_ is a vessel of iron, supported upon
wooden standards _b b_, over the upper surface of which vessel a sheet
or diaphragm, _c c_, of oiled cloth, or other suitable elastic material,
is distended, and made fast at its edges by being bent over a flange,
and packed or cemented to render the joints water-tight. A vertical pipe
_d_ is intended to conduct water to the interior of the vessel _a_, and,
by a small elevation of the column, to create such upward pressure as
shall give to the diaphragm a slight bulge like the swimming tub.

An endless web, _e e e_, passing over the surface of the diaphragm, is
distended over three rollers, _f g h_, the lower of which, _f_, is in
contact with the colour-roller _i_ in the colour-trough K. On the axle
of the roller _i_ a pulley wheel is fixed, which allows the roller to be
turned by a band from any first mover; or the roller may receive
rotatory motion by a winch fixed on its axle. On this said axle there is
also a toothed wheel, taking into another toothed wheel on the axle of
the roller _f_; hence, the rotation of the colour-roller _i_ in the one
direction will cause the roller _f_ to revolve in the opposite, and to
carry forward the endless web _e e e_, over the elastic diaphragm, the
web taking with it a stratum of colour received from the roller _i_,
evenly distributed over its surface, and ready for the printer to dip
his block into.

The axles of the rollers _f_ and _g_ turn in stationary bearings; but
the axle of _h_ is mounted in sliding nuts, which may be moved by
turning the screws _m_, for the purpose of tightening the endless web.
The axle of the colour-roller _i_ turns in mortises, and may be raised
by screws _n_, in order to bring its surface into contact with the
endless web. To prevent too great a quantity of colour being taken up,
the endless web passes through a long slit, or parallel aperture, in a
frame _o_, which acts as a scraper or doctor, and is adjustable by a
screw _p_, to regulate the quantity of colour carried up. The contents
of the vessel _a_, and of the colour-trough K, may be discharged when
required by a cock in the bottom of each. See PAPER HANGINGS, for the
_Fondu_ style.


CALOMEL. (_Chlorure de Mercure_, Fr.; _Versüsstes Quecksilber_, Germ.)
The mild protochloride of mercury. The manufacture of this substance
upon the great scale may be performed in two ways. The cheapest and most
direct consists in mixing 1-1/8 part of pure quicksilver with 1 part of
pure nitric acid, of sp. grav. from 1·2 to 1·25; and in digesting the
mixture till no more metal can be dissolved, or till the liquid has
assumed a yellow colour. At the same time, a solution of 1 part of
common salt is made in 32 parts of distilled water, to which a little
muriatic acid is added; and, when heated to nearly the boiling point, it
is mixed with the mercurial solution. The two salts exchange bases, and
a protochloride of mercury precipitates in a white powder, which, after
being digested for some time in the acidulous supernatant liquor, is to
be washed with the greatest care in boiling water. The circumstances
which may injure the process are the following:--1. When less mercury is
employed than the acid can dissolve, there is formed a deuto-nitrate of
mercury, which forms some corrosive sublimate with the common salt, and
causes a proportional defalcation of calomel. 2. If the liquors are
perfectly neutral at the moment of mixing them, some subnitrate of
mercury is thrown down, which cannot be removed by washing, and which
gives a noxious contamination to the bland calomel. The acid prescribed
in the above formula obviates this danger.

The second manner of manufacturing calomel is to grind very carefully 4
parts of corrosive sublimate (bi-chloride of mercury) with 3 parts of
quicksilver, adding a little water or spirits to repress the noxious
dust during the trituration. The mass is then introduced into a glass
globe, and sublimed at a temperature gradually raised. The quicksilver
combines with the deutochloride, and converts it into the protochloride,
or calomel. The following formula, upon the same principle, was
recommended to the chemical manufacturer in Brande’s Journal, for July,
1818:--

“Prepare an oxysulphate of mercury, by boiling 25 pounds of mercury with
35 pounds of sulphuric acid to dryness. Triturate 31 pounds of this dry
salt with 20 pounds 4 ounces of mercury, until the globules disappear,
and then add 17 pounds of common salt. The whole is to be thoroughly
mixed, and sublimed in earthen vessels. Between 46 and 48 pounds of pure
calomel are thus produced: it is to be washed and levigated in the usual
way.” The above is the process used at Apothecaries’ Hall, London. The
oxysulphate is made in an iron pot; and the sublimation is performed in
earthen vessels. The crystalline crust or cake of calomel should be
separated from the accompanying gray powder, which is nearest the glass,
and consists of mercury mixed with corrosive sublimate.

An ingenious modification of the latter process, for which a patent, now
expired, was obtained by Mr. Jewell, consists in conducting the sublimed
vapours over an extensive surface of water contained in a covered
cistern. The calomel thus obtained is a superior article, in an
impalpable powder, propitious to its medical efficacy.

The presence of corrosive sublimate in calomel is easily detected by
digesting alcohol upon it, and testing the decanted alcohol with a drop
of caustic potash, when the characteristic brick-coloured precipitate
will fall, if any of the poisonous salt be present. To detect subnitrate
of mercury in calomel, digest dilute nitric acid on it, and test the
acid with potash, when a precipitate will fall in case of that
contamination. As it is a medicine so extensively administered to
children at a very tender age, its purity ought to be scrupulously
watched.

118 parts of calomel contain 100 of quicksilver.


CALORIC. The chemical name of the power or matter of heat.


CALORIFÈRE OF WATER. (_Calorifère d’eau_, Fr.; _Wasser-Heitzung_, Germ.)
In the _Dictionnaire Technologique_, vol. iv., published in 1823, we
find the following description of this apparatus, of late years so much
employed in Great Britain for heating conservatories, &c. by hot water
circulating in pipes:--

[Illustration: 252]

“This mode of heating is analogous to that by stove pipes: it is
effected by the circulation of water, which, like air, is a bad
conductor, but may serve as a carrier of caloric by its mobility. We may
readily form an idea of the apparatus which has been employed for this
purpose. We adapt to the upper part of either a close kettle, or of an
ordinary cylindric boiler A, _fig._ 252, a tube B, which rises to a
certain height, then descends, making several sinuosities with a gentle
slope till it reaches the level of the bottom of the boiler, to whose
lowest part, as that which is least heated, it is fitted at C. At the
highest point of the tube F we adapt a vertical pipe, destined to serve
as an outlet to the steam which may be formed if the temperature be too
much raised: it serves also for the escape of the air expelled from the
water by the heat; and it permits the boiler to be replenished from time
to time as the water is dissipated by evaporation; lastly, it is a tube
of safety.

“The apparatus being thus arranged, and all the tubes as well as the
boiler filled with water, if we kindle fire in the grate D, the first
portions of water heated, having become specifically lighter, will tend
to rise: they will actually mount into the upper part of the boiler,
and, of course, enter the tube B F: at the same time an equivalent
quantity of water will re-enter the boiler by the other extremity C of
the tube. We perceive that these simultaneous movements will determine a
circulation in the whole mass of the liquid, which will continue as long
as heat is generated in the fire-place; and if we suppose that the
tubes, throughout their different windings, are applied against the
walls of a chamber, or a stove-room, the air will get warmed by contact
with the hot surfaces; and we may accelerate the warming by multiplying
these contacts in the mode indicated.

“This _calorifère_ cannot be employed so usefully as those with heated
air, when it is wished to heat large apartments. In fact, the passage of
heat through metallic plates is in the ratio of the difference of
temperature and quantity of the heating surfaces. In the present case,
the temperature of the water, without pressure, in the tubes, must be
always under 100° C. (212° F.), even in those points where it is most
heated, and less still in all the other points, while the temperature of
the flues in _air stoves_, heated directly by the products of
combustion, may be greatly higher. In these stoves, also, the pipes may
without inconvenience have a large diameter, and present, consequently,
a large heating surface; whereas, with the water _calorifère_, the
pressure exercised by the liquid upon the sides of the tubes being in
the ratio of the surfaces, we are obliged, in order to avoid too great
pressure, to employ a multitude of small tubes, which is expensive.
Lastly, if the hot-water circulation is to be carried high, as may be
often necessary in lofty buildings, the pressure resulting from the
great elevation would call for proportional thickness in the tubes and
the boiler: for these reasons, and others which we shall state in
treating of heating by steam, it appears that water cannot be
advantageously substituted for air or steam in the applications above
stated; yet this mode of heating presents very decided advantages where
it is useful to raise the temperature a small number of degrees in a
uniform manner.” See INCUBATION, ARTIFICIAL.

“M. Bonnemain applied, with much success, these ingenious processes of
heating by the circulation of water, to maintain a very equal
temperature in hot-houses (_serres-chaudes_), in stoves adapted to
artificial incubation, and in preserving or quickening vegetation within
hot-houses, or outside of their walls, during seasons unpropitious to
horticulture.

“Since the capacity of water for heat is very great, if the mass of it
in a circulation-apparatus be very considerable, and the circulation be
accelerated by proper arrangements, as by cooling the descending tube
exterior to the stove-room, we may easily obtain by such means a
moderately high and uniform temperature, provided the heat generated in
the fire-place be tolerably regular. We may easily secure this essential
point by the aid of the _fire-regulator_, an instrument invented by M.
Bonnemain, and which is described under the article INCUBATION, because
there its use seems to be indispensable.”

From the above quotation, and, more especially, from the evidence
adduced in the article INCUBATION, we see how little claim the Marquis
de Chabannes, or any of his followers, can have to invention in their
arrangements for heating apartments by the calorific motions of the
particles of water, enclosed in pipes of any kind.


CAMBRIC. (_Batiste_, Fr.; _Kammertuch_, Germ.) A sort of very fine and
rather thin linen fabric, first made at Cambray. An excellent imitation
of this fabric is made in Lancashire, woven from fine cotton yarn hard
twisted. Linen cambric of a good quality is also now manufactured in the
United Kingdom from power-spun flax.


CAMLET OR CAMBLET. A light stuff, much used for female apparel. It is
made of long wool hard spun, sometimes mixed in the loom with cotton or
linen yarn.


CAMPHOR, or CAMPHIRE. This immediate product of vegetation was known to
the Arabs under the names of _kamphur_ and _kaphur_, whence the Greek
and Latin name _camphora_. It is found in a great many plants, and is
secreted, in purity, by several laurels: it occurs combined with the
essential oils of many of the _labiatæ_; but it is extracted, for
manufacturing purposes only, from the _Laurus camphora_, which abounds
in China and Japan, as well as from a tree which grows in Sumatra and
Borneo, called, in the country, _Kapour barros_, from the name of the
place where it is most common. The camphor exists, ready formed, in
these vegetables, between the wood and the bark; but it does not exude
spontaneously. On cleaving the tree _Laurus sumatrensis_, masses of pure
camphor are found in the pith.

The wood of the laurus is cut into small pieces, and put, with plenty of
water, into large iron boilers, which are covered with an earthen
capital or dome, lined within with rice straw. As the water boils, the
camphor rises with the steam, and attaches itself as a sublimate to the
stalks, under the form of granulations of a grey colour. In this state
it is picked off the straw, and packed up for exportation to Europe.

Formerly Venice held the monopoly of refining camphor, but now France,
England, Holland, and Germany refine it for their own markets. All the
purifying processes proceed on the principle that camphor is volatile at
the temperature of 400° F. The substance is mixed, as intimately as
possible, with 2 per cent. of quicklime, and the mixture is introduced
into a large bottle made of thin uniform glass, sunk in a sand bath. The
fire is slowly raised till the whole vessel becomes heated, and then its
upper part is gradually laid bare in proportion as the sublimation goes
on. Much attention and experience are required to make this operation
succeed. If the temperature be raised too slowly, the neck of the bottle
might be filled with camphor before the heat had acquired the proper
subliming pitch; and, if too quickly, the whole contents might be
exploded. If the operation be carried on languidly, and the heat of the
upper part of the bottle be somewhat under the melting point of camphor,
that is to say, a little under 350° F., the condensed camphor would be
snowy, and not sufficiently compact and transparent to be saleable.
Occasionally, sudden alternations of temperature cause little jets to be
thrown up out of the liquid camphor at the bottom upon the cake formed
above, which soil it, and render its re-sublimation necessary.

If, to the mixture of 100 parts of crude camphor and 2 of quicklime, 2
parts of bone-black, in fine powder, be added, the small quantity of
colouring matter in the camphor will be retained at the bottom, and
whiter cakes will be produced. A spiral slip of platina foil immersed in
the liquid may tend to equalise its ebullition.

By exposing some volatile oils to spontaneous evaporation, at the heat
of about 70° F., Proust obtained a residuum of camphor; from oil of
lavender, 25 per cent. of its weight; from oil of sage, 12-1/2; from oil
of marjoram, 10.

Refined camphor is a white translucid solid, possessing a peculiar taste
and smell. It may be obtained, from the slow cooling of its alcoholic
solution, in octahedral crystals. It may be scratched by the nail, is
very flexible, and can be reduced into powder merely by mixing it with a
few drops of alcohol. Its specific gravity varies from 0·985 to 0·996.
Mixed and distilled with six times its weight of clay, it is decomposed,
and yields a golden yellow aromatic oil, which has a flavour analogous
to that of a mixture of thyme and rosemary; along with a small quantity
of acidulous water tinged with that oil, charcoal remains in the retort.
In the air, camphor takes fire on contact of an ignited body, and burns
all away with a bright fuliginous flame.

Camphor is little soluble in water; one part being capable of
communicating smell and taste to 1000 of the fluid. 100 parts of
alcohol, spec. grav. 0·806, dissolve 120 parts of camphor, at ordinary
temperatures. It is separated, in a pulverulent state, by water. Ether
and oils, both expressed and volatile, also dissolve it.

When distilled with eight parts of aquafortis, camphor is converted into
camphoric acid. Camphor absorbs 144 times its volume of muriatic acid
gas, and is transformed into a colourless transparent liquid, which
becomes solid in the air, because the acid attracts humidity, which
precipitates the camphor. One part of strong acetic acid dissolves two
parts of camphor. By my analysis, camphor consists of 77·38 carbon,
11·14 hydrogen, and 11·48 oxygen. Berzelius’s numbers are certainly
erroneous.


CAMWOOD. An article imported from Sierra Leone, which seems to possess
similar dyeing powers with Brazil or Nicaragua wood.


CANDLE. (_Chandelle_, Fr.; _Kerze_, _Licht_, Germ.) I shall first
briefly describe the ordinary manufacture of candles. They are either
dipped or moulded. But the first part of the process is the sorting of
the tallow. Mutton suet with a proportion of ox-tallow is selected for
mould candles, because it gives them gloss and consistence. Coarser
tallow is reserved for the dipped candles. After being sorted, it is cut
into small pieces, preparatory to being melted or _rendered_; and the
sooner this is done after the fat is taken from the carcase the better,
because the fibrous and fleshy matters mixed with it promote its
putrefaction. Tallow is too commonly melted by a naked fire applied to
the bottom of the vessel, whereas it should be done either in a cold set
pan, where the flame plays only round the sides a little way above the
bottom, or in a steam-cased pan. After being fused a considerable time,
the membranous matters collect at the surface, constituting the
_cracklings_ used sometimes for feeding dogs, after the fat has been
squeezed out of it by a press. The liquid tallow is strained through a
sieve into another copper, where it is treated with water at a boiling
temperature in order to wash it. After a while, when the foul water has
settled to the bottom, the purified tallow is lifted out, by means of
tinned iron buckets, into tubs of a moderate size, where it concretes,
and is ready for use.

It is a remarkable circumstance, that the wicks for the best candles are
still cotton rovings imported from Turkey, notwithstanding the vast
extension and perfection of cotton-spinning in this country. Four or
more of these Turkey skeins, according to the intended thickness of the
wick, are wound off at once into bottoms or clues, and afterwards cut by
a simple machine into lengths corresponding to those of the candles to
be made. Mr. Colebank obtained a patent, in June, 1822, for a machine
for cutting, twisting, and spreading wicks, which, though convenient,
does not seem to have come into general use. The operations are
performed upon a series of threads at once. The apparatus is placed in a
box, in front of which the operator sits. A reel extends across the box,
at the hinder part, upon which the cotton threads have been previously
wound: from this reel they are drawn off in proper lengths, doubled, and
cut by an ingenious mechanism. By dipping the wicks into the melted
tallow, rubbing them between the palms of the hands, and allowing the
tallow which adheres to harden, they may be arranged with facility upon
the broaches for the purpose of dipping. The dipping room is furnished
with a boiler for melting the tallow, the dipping mould, or cistern, and
a large wheel for supporting the broaches. From the ceiling of the
workshop a long balance-shaped beam is suspended, to one end of which a
wooden frame is attached for holding the broaches with the wicks
arranged at proper distances. The opposite arm is loaded with a weight
to counterbalance the wooden frame, and to enable the workman to
ascertain the proper size of the candles. The end of the lever which
supports the frame is placed immediately above the dipping cistern; and
the whole machine is so balanced that, by a gentle pressure of the hand,
the wicks are let down into the melted tallow as often as may be
required.

[Illustration: 253]

The following convenient apparatus for dipping candles has been long in
use at Edinburgh. In the centre of the dipping-room a strong upright
post A A, _fig._ 253., is erected, with turning iron pivots at its two
ends. Near its middle, six mortises are cut at small distances from one
another, into each of which is inserted a long bar of wood B B, which
moves vertically upon an iron pin, also passing through the middle of
the shaft. The whole presents the appearance of a large horizontal wheel
with twelve arms. A complete view of two of them only is given in the
figure. From the extremity of each arm is suspended a frame, or port, as
the workmen call it, containing 6 rods, on each of which are hung 18
wicks, making the whole number of wicks upon the wheel 1296. The
machine, though apparently heavy, turns round by the smallest effort of
the workman; and each port, as it comes in succession over the
dipping-mould, is gently pressed downwards, by which means the wicks are
regularly immersed in melted tallow. As the arms of the lever are all of
the same length, and as each is loaded with nearly the same weight, it
is obvious that they will all naturally assume a horizontal position. In
order, however, to prevent any oscillation of the machine in turning
round, the levers are kept in a horizontal position by means of small
chains _a a_, one end of which is fixed to the top of the upright shaft,
and the other terminates in a small square piece of wood _b_, which
exactly fills the notch _c_ in the lever. As one end of the levers must
be depressed at each dip, the square piece of wood is thrown out of the
notch by the workman pressing down the handle D, which communicates with
the small lever _e_, inserted into a groove in the bar B. In order that
the square piece of wood, fixed in one extremity of the chain, may
recover its position upon the workman’s raising the port, a small cord
is attached to it, which passes over a pulley inserted in a groove near
_c_, and communicates with another pulley and weight, which draws it
forward to the notch. In this way the operation of dipping may be
conducted by a single workman with perfect ease and regularity, and even
dispatch. No time is lost, and no unnecessary labour expended, in
removing the ports after each dip; and, besides, the process of cooling
is much accelerated by the candles being kept in constant motion through
the air. The number of revolutions which the wheel must make, in order
to complete one operation, must obviously depend upon the state of the
weather and the size of the candles; but it is said that, in moderately
cold weather, not more than two hours are necessary for a single person
to finish one wheel of candles of a common size. Upon the supposition,
therefore, that six wheels are completed in one day, no less a number
than 7776 candles will be manufactured in that space of time by one
workman.

I shall next describe the process of moulding, which, if possible, is
even less complicated in its details than that of dipping. The moulds
are made of some metallic substance, usually pewter, and consist of two
parts. The shaft or great body of the mould is a hollow cylinder, finely
polished in the inside, and open at both extremities. The top of the
mould is a small metallic cup, having a moulding within-side, and a hole
to admit the wick. The two parts are soldered together, and when united,
as will readily be imagined, have the shape of a moulded candle. A third
piece, called the foot, is sometimes added; it is a kind of small
funnel, through which the liquid tallow runs into the mould, and, being
screwed to the opposite extremity of the shaft, is removable at
pleasure. This additional piece may certainly be useful in very mild
weather; since, by removing it, the candles may be drawn more easily
from the moulds; but, in general, it may be dispensed with.

Eight or twelve of these moulds, according to their size, are fixed in a
frame, which bears a great resemblance to a wooden stool, the upper
surface of which forms a kind of trough. The top of the moulds points
downwards, and the other extremity, which is open, is inserted into the
bottom trough or top of the stool, and made quite level with its upper
surface. In order to introduce the wicks into the mould, the workman
lays the frame upon its side on an adjoining table, and holding in his
left hand a quantity of wicks, previously cut to the proper length, he
introduces into the mould a long wire with a hooked point. As soon as
the hook of the wire appears through the hole in the top of the mould,
he attaches to it the looped end of the wick, and, immediately drawing
back the wire, carries the wick along with it. In this manner each mould
in succession is furnished with a wick. Another workman now follows, and
passes a small wire through the loop of each wick. This wire is
obviously intended to keep the wick stretched, and to prevent it from
falling back into the mould upon the frame being placed in the proper
position for filling. The frame is then handed to the person that fills
the moulds, who previously arranges the small wires in such a manner
that each wick may be exactly in the middle of the mould.

The moulds are filled by running tallow into each of them, or into the
trough, from a cistern furnished with a cock, and which is regularly
supplied with tallow of the proper temperature from an adjoining boiler.
When the workman observes that the moulds are nearly half filled he
turns the cock, and, laying hold of that portion of the wick which hangs
out of the mould, pulls it tight, and thus prevents any curling of the
wick, which might injure the candles: he then opens the cock, and
completes the process of filling. The frame is now set aside to cool;
and when the tallow has acquired a proper consistence, which the workman
easily discovers by a snapping noise emitted by the candles upon
pressing his thumb against the bottom of the moulds, he first withdraws
the small wires which kept the wicks tense, and then, scraping off the
loose tallow from the top of the frame with a small wooden spade, he
introduces a bodkin into the loop of the wick, and thus draws each
candle in succession from its mould. The candles are now laid upon a
table for the inspection of the exciseman, and afterwards removed to the
storehouse. Previous to storing them up, some candle-makers bleach their
candles, by exposing them to the air and dews for several days. This
additional labour can be necessary only when the dealer is obliged to
have early sales; for if the candles are kept for some months, as they
ought to be, before they are brought to market, they become sufficiently
whitened by age.

_Wax candles._--Next to tallow, the substance most employed in the
manufacture of candles is wax. Wax candles are made either by the hand
or with a ladle. In the former case, the wax, being kept soft in hot
water, is applied bit by bit to the wick, which is hung from a hook in
the wall; in the latter, the wicks are hung round an iron circle, placed
immediately over a large copper-tinned basin full of melted wax, which
is poured upon their tops, one after another, by means of a large ladle.
When the candles have by either process acquired the proper size, they
are taken from the hooks, and rolled upon a table, usually of
walnut-tree, with a long square instrument of box, smooth at the bottom.

A few years ago I made a set of experiments upon the relative
intensities of light, and duration of different candles, the results of
which are contained in the following table.

  +----------+-----------+-------+--------+-------+-------+---------+
  |          |           |       |Consump-|Propor-|       |         |
  |  Number  | Duration  | Weight|tion per| tion  | Econ- |Candles  |
  |   in a   |   of a    |   in  |hour in |  of   | omy of|equal one|
  |  pound.  |  candle.  |grains.|grains. |light. | light.|Argand.  |
  +----------+-----------+-------+--------+-------+-------+---------+
  |          |_h._ _m._  |       |        |       |       |         |
  |10 mould  | 5    9    |  682  |  132   | 12-1/4| 68    |  5·7    |
  |10 dipped | 4   36    |  672  |  150   | 13    | 65-1/2|  5·25   |
  | 8 mould  | 6   31    |  856  |  132   | 10-1/2| 59-1/2|  6·6    |
  | 6 ditto  | 7    2-1/2| 1160  |  163   | 14-2/3| 66    |  5·0    |
  | 4 ditto  | 9    3·6  | 1707  |  186   | 20-1/4| 80    |  3·5    |
  |Argand oil|   --      |   --  |  512   | 69·4  |100    |         |
  |flame     |           |       |        |       |       |         |
  +----------+-----------+-------+--------+-------+-------+---------+

A Scotch mutchkin, or 1/8 of a gallon of good seal oil, weighs 6010 gr.,
or 13-1/10 oz., avoirdupois, and lasts in a bright Argand lamp 11 hours
44 minutes. The weight of oil it consumes per hour is equal to 4 times
the weight of tallow in candles 8 to the pound, and 1/7 the weight of
tallow in candles 6 to the pound. But, its light being equal to that of
5 of the latter candles, it appears from the above table that 2 pounds
weight of oil, value 9_d._ in an Argand, are equivalent in illuminating
power to 3 pounds of tallow candles, which cost about two shillings. The
larger the flame in the above candles the greater the economy of light.

In June, 1825, M. Gay Lussac obtained a patent in England for making
candles from _margaric and stearic acids_, improperly called _stearine_,
by converting tallow into the above fat acids by the following
process:--Tallow consists, by Chevreul’s researches, of stearine, a
solid fat, and elaine, a liquid fat; the former being in much the larger
proportion. When tallow is treated with an alkaline body, such as
potash, soda, or lime, it is saponified; that is, its stearine and
elaine become respectively stearic and elaic acids, and, as such, form
compounds with these bases. When by the action of an acid, such as the
sulphuric or muriatic, these combinations are decomposed, the fats
reappear in the altered form of stearic and elaic acids; the former body
being harder than tallow, and of a texture, somewhat like spermaceti,
the latter body being fluid, like oil. “The decomposition of the soap
should be made,” says the patentee, “in a large quantity of water, kept
well stirred during the operation, and warmed by steam introduced in any
convenient way. When the mixture has been allowed to stand, the acid of
the tallow or fat will rise to the surface, and the water being drawn
off will carry the alkaline or saline matters with it; but, if the acids
of the tallow should retain any portion of the salts, fresh water may
be thrown upon it, and the whole well agitated, until the acids have
become perfectly free from the alkaline matters; and, when allowed to
cool, the acids will be formed into a solid mass. This mass is now to be
submitted to considerable pressure in such an apparatus as is employed
in expressing oil from seeds; when the liquid acid will run off in the
form of a substance resembling oil, leaving a solid matter, similar, in
every respect, to spermaceti, which is fit for making candles.”

The wick to be used in the manufacture of these improved candles, and
which forms one of the features of this invention, is to be made of
cotton yarn, twisted rather hard, and laid in the same manner as wire is
sometimes coiled round the bass strings of musical instruments. For this
purpose, straight rods or wires are to be procured, of suitable lengths
and diameters, according to the intended size of the candles about to be
made; and these wires, having been covered with cotton coiled round
them, as described, are to be inserted in the candle moulds as the
common wicks are; and when the candle is made, and perfectly hard, the
wire is to be withdrawn, leaving a hollow cylindrical aperture entirely
through the middle of the candle. See STEARINE.


CANE-MILL. See MILL and SUGAR.


CANNON. For the composition of these implements of destruction, see
BRONZE.


CANVASS (_Canevas_, Fr.; _Segeltuch_, Germ.) It has been found that
sails of ships made with the selvages and seams of the canvass running
down parallel to their edges, are very apt to bag, and become torn in
the middle, from the strain to which they are subjected by the pressure
of the wind. To obviate this inconvenience, a mode of making sails, with
the seams and selvages running diagonally, was proposed by Admiral
Brooking, and a patent granted to him for the same on 4th of September,
1828. The invention of Messrs. Ramsay and Orr, which we are about to
describe, has a similar object, viz., that of giving additional strength
to sails by a peculiar manner of weaving the canvass of which they are
made.

The improvement proposed under their patent of March, 1830, consists in
weaving the canvass with diagonal threads; that is, placing the weft
yarn, or shoot, in weaving, at an oblique angle to the warp yarns,
instead of making the decussation of the warp, or weft threads, or
yarns, at right angles to each other, as in the ordinary mode of
weaving.

To accomplish this object the loom must be peculiarly constructed; that
is, its warp and work beams must stand at an oblique angle with the
sides of the loom, and the batten and slay must be hung in a peculiar
manner, in order to beat up the weft, or shoot, in lines ranging
diagonally with the warp. No drawing is shown of the method by which
this arrangement of the loom is to be made, but it is presumed that any
weaver would know how to accomplish it: the invention consisting solely
in producing sail cloth with the threads, or yarns, of the weft ranging
diagonally at any desired angle with the direction of the warp thread.


CAOUTCHOUC, GUM-ELASTIC, OR INDIAN-RUBBER, (_Federharz_, Germ.) occurs
as a milky juice in several plants, such as the _siphonia cahuca_,
called also _hevea guianensis_, _cautschuc_, _jatropha elastica_,
_castilleja elastica_, _cecropia pellata_, _ficus religiosa_ and
_indica_, _urceolaria elastica_, &c. It is, however, extracted chiefly
from the first plant, which grows in South America and Java. The tree
has incisions made into it through the bark in many places, and it
discharges the milky juice, which is spread upon clay moulds, and dried
in the sun, or with the smoke of a fire, which blackens it.

The juice itself has been of late years imported. It is of a pale yellow
colour, and has the consistence of cream. It becomes covered in the
bottles containing it with a pellicle of concrete caoutchouc. Its spec.
grav. is 1·012. When it is dried it loses 55 per cent. of its weight:
the residuary 45 is elastic gum. When the juice is heated it immediately
coagulates, in virtue of its albumen, and the elastic gum rises to the
surface. It mixes with water in any proportion; and, when thus diluted,
it coagulates with heat and alcohol as before.

The specific gravity of caoutchouc is 0·925, and it is not permanently
increased by any degree of pressure. By cold or long quiescence it
becomes hard and stiff. When the milky juice has become once coherent,
no means hitherto known can restore it to the emulsive state. By long
boiling in water it softens, swells, and becomes more readily soluble in
its peculiar menstrua; but when exposed to the air it speedily resumes
its pristine consistence and volume. It is quite insoluble in alcohol;
but in ether, deprived of alcohol by washing with water, it readily
dissolves, and affords a colourless solution. When the ether is
evaporated, the caoutchouc becomes again solid, but is somewhat clammy
for a while. When treated with hot naphtha, distilled from native
petroleum, or from coal tar, it swells to 30 times its former bulk; and
if then triturated with a pestle, and pressed through a sieve, it
affords a homogeneous varnish, which being applied by a flat edge of
metal or wood to cloth, prepares it for forming the patent water-proof
cloth of Mackintosh. Two surfaces of cloth, to which several coats of
the above varnish have been applied, are, when partially dried, brought
evenly in contact, and then passed between rollers, in order to condense
and smooth them together. This double cloth is afterwards suspended in
a stove-room to dry, and to discharge the disagreeable odour of the
naphtha.

Caoutchouc dissolves in the fixed oils, such as linseed oil, but the
varnish has not the property of becoming concrete upon exposure to air.

It has been lately asserted that caoutchouc is soluble in the oils of
lavender and sassafras.

It melts at 248° F., and stands afterwards a much higher heat without
undergoing any further change. When the melted caoutchouc is exposed to
the air, it becomes hard on the surface in the course of a year. When
kindled it burns with a bright flame and a great deal of smoke.

Neither chlorine, sulphurous acid gas, muriatic acid gas, ammonia, nor
fluosilicic acid gas, affect it, whence it forms very valuable flexible
tubes for pneumatic chemistry. Cold sulphuric acid does not readily
decompose it, nor does nitric acid, unless it be somewhat strong. The
strongest caustic potash lye does not dissolve it even at a boiling
heat.

Caoutchouc, according to my experiments, which have been confirmed by
those of Mr. Faraday, contains no oxygen, as almost all other solid
vegetable products do, but is a mere compound of carbon and hydrogen, in
the proportion, by my results, of 90 carbon to 10 hydrogen, being three
atoms of the former to two of the latter. Mr. Faraday obtained only 87·2
carbon, from which I would infer that some of the carbon, which in this
substance is difficult to acidify by peroxide of copper, had escaped its
action. It is obvious that too little carbonic acid gas may be obtained,
but certainly not more than corresponds to the carbon in the body. No
carbon can be created in the process of ultimate analysis by pure
peroxide of copper such as I employed; and I repeated the ignition after
attrition of the mixture used in the experiment. Melted caoutchouc forms
a very excellent chemical lute, as it adheres very readily to glass
vessels, and withstands the corrosive action of acid vapours. This
substance is much used for effacing the traces of plumbago pencils,
whence it derived the name of Indian-rubber. It has been lately employed
very extensively for making elastic bands or braces. The caoutchouc
bottles are skilfully cut into long spiral slips, which are stretched,
and kept extended till nearly deprived of their elasticity, and till
they form a thread of moderate fineness. This thread is put into a braid
machine, and covered with a sheath of cotton, silk, linen, or worsted.
The clothed caoutchouc is then laid as warp in a loom, and woven into an
elegant riband. When woven, it is exposed, upon a table to the action of
a hot smoothing iron, which restoring to the caoutchouc all its
primitive elasticity, the riband retracts considerably in length, and
the braiding corrugates equally upon the caoutchouc cores. Such bands
possess a remarkable elasticity, combined with any desired degree of
softness. Sometimes cloth is made of these braided strands of caoutchouc
used both as warp and as weft, which is therefore elastic in all
directions. When a light fabric is required, the strands of caoutchouc,
either naked or braided, are alternated with common warp yarns. For this
mixed fabric a patent has been obtained. The original manufacturer of
these elastic webs is a major in the Austrian service, who has erected a
great factory for them at St. Denys, near Paris. See ELASTIC BANDS.

[Illustration: 254]

Mr. William Henry Barnard, in the course of some experiments upon the
impregnation of ropes with caoutchouc, at the factory of Messrs. Enderby
at Greenwich, discovered that when this substance was exposed to a heat
of about 600° F. it resolved itself into a vapour, which, by proper
refrigeratory methods, was condensable into a liquid possessing very
remarkable properties, to which the name caoutchoucine has been given.
For this invention “of a solvent not hitherto used in the arts” Mr.
Barnard obtained a patent, in August, 1833. His process for preparing it
is described in his specification as follows:--I take a mass of the said
caoutchouc, or Indian rubber, as imported, and having cut it into small
lumps, containing about two cubic inches each (which I prefer), I throw
these lumps into a cast-iron still (which I find adapted for the
purpose, and a diagram of which is annexed to, and forms part of, this
my specification), with a worm attached; _fig._ 254., A is the still, B
the cover ground to a metallic fit, to admit of a thermometer to take
the temperature; C the fire-place, D the ash-pit, E the worm-tub and
worm, F the brick-work of the still, G a roller and carriage, in
conjunction with a crane, or other means, to raise the cover to take out
the residue, and to charge the same; H the chain.

I then apply heat to the still in the usual manner, which heat is
increased until the thermometer ranges at 600 degrees of Fahrenheit, or
thereabouts. And, as the thermometer ranges progressively upwards to 600
degrees of Fahrenheit, a dark-coloured oil or liquid is distilled over,
which I claim as my said invention, such liquid being a solvent of
caoutchouc, and other resinous and oleaginous substances. When the
thermometer reaches 600 degrees, or thereabouts, nothing is left in the
still but dirt and charcoal.

I have found the operation of distillation to be facilitated by the
addition of a portion of this oil, either previous or subsequent to
rectification, as hereinafter mentioned, in the proportion of one third
of oil to two thirds of caoutchouc.

I afterwards subject the dark-coloured liquid thus distilled to the
ordinary process of rectification, and thereby obtain fluids varying in
specific gravity, of which the lightest hitherto has not been under 670,
taking distilled water at 1000, which fluids I also claim as my said
invention.

At each rectification the colour of the liquid becomes more bright and
transparent, until at the specific gravity of 680, or thereabouts, it is
colourless and highly volatile.

In the process of rectification (for the purpose of obtaining a larger
product of the oil colourless) I put about one third of water into the
still. In each and every state the liquid is a solvent of caoutchouc,
and several resinous and oleaginous substances, and also of other
substances (such as copal), in combination with very strong alcohol.

Having experienced much difficulty in removing the dirt which adheres to
the bottom of the still, I throw into the still, lead and tin in a state
of alloy (commonly called solder), to the depth of about half an inch,
and, as this becomes fused, the dirt which lies on the surface of it is
more easily removed.

Objections have been made to the smell of this liquid:--I have found
such smell removed by mixing and shaking up the liquid with
nitro-muriatic acid, or chlorine, in the proportion of a quarter of a
pint of the acid (of the usual commercial strength) to a gallon of the
liquid.

The discovery of the chemical solvent, which forms the subject of the
patent above described, has excited considerable interest in the
philosophic world, not only from its probable usefulness as a new
article of commerce, but also from two very extraordinary
characteristics which it is found to possess, viz., that, in a liquid
state, it has less specific gravity than any other liquid known to
chemists, being considerably lighter than sulphuric ether, and, in a
state of vapour, is heavier than the most ponderous of the gases.

Its elementary constituents are,

  Carbon       6·812     8 proportions.
  Hydrogen     1·000     7 ditto.

This new material (when mixed with alcohol) is a solvent of all the
resins and particularly of copal, which it dissolves, without artificial
heat, at the ordinary temperature of the atmosphere; a property
possessed by no other solvent known; and hence it is peculiarly useful
for making varnishes in general. It also mixes readily with oils, and
will be found to be a valuable and cheap menstruum for liquefying
oil-paints; and without in the slightest degree affecting the most
delicate colours, will, from its ready evaporation, cause the paint to
dry almost instantly.

Cocoa-nut oil, at the common temperature of the atmosphere, always
assumes a concrete form; but a portion of this caoutchoucine mixed with
it will cause the oil to become fluid, and to retain sufficient fluidity
to burn in a common lamp with extraordinary brilliancy.

Caoutchoucine is extremely volatile; and yet its vapour is so
exceedingly heavy, that it may be poured, without the liquor, from one
vessel into another like water.


CAPERS. The caper is a small prickly shrub, cultivated in Spain, Italy,
and the southern provinces of France. The flowers are large roses of a
pretty appearance, but the flower buds alone are the objects of this
cultivation.

They are plucked before they open, and thrown into strong vinegar
slightly salted, where they are pickled. The crop of each day is added
to the same vinegar tub, so that in the course of the six months during
which the caper shrub flowers, the vessel gets filled, and is sold to
persons who sort the capers, (the smallest being most valued) by means
of copper sieves. This metal is attacked by the acid, wherefrom the
fruit acquires a green colour, much admired by _ignorant connoisseurs_.

The capers, as found in the French market, are distinguished into five
sorts; the _non-pareille_, the _capucine_, the _capote_, the _second_,
and the _third_; this being the decreasing order of their quality, which
depends upon the strength of the vinegar used in pickling them, as also
the size and colour of the buds.

The caper shrub grows in the driest situations, even upon walls, and
does not disdain any soil; but it loves a hot and sheltered exposure. It
is multiplied by grafts made in autumn, as also by slips of the roots
taken off in spring.


CAPSTAN. (_Cabestan_, Fr.; _Spille_, Germ.) A machine whereon the cable
is wound successively in weighing the anchor of a vessel. It is a
species of wheel and axle; the axle being vertical, and pierced with
holes near its top for the insertion of the ends of horizontal levers,
called handspikes, which represent the wheel. These are turned by the
force of men moving in a circle. The power applied to the lever is to
the resistance to be overcome, (the weight of the anchor, for example,)
when the forces are in equilibrio, as the radius of the cylinder round
which the cable is coiled is to the circumference described by the
power.

It is manifest that the radius of the axle must be augmented in this
computation by half the diameter of the cable, which is supposed to lie
always one coil thick upon it. The force of a man, thus applied, has
been commonly estimated as equal to the traction of 27 pounds hanging
over a pulley.

Friction being so variable a quantity in capstans, renders the exact
calculation of its mechanical effect somewhat uncertain.

A stout man, stationed near the bottom of the axle, holds fast the loose
part of the cable, which has already made two or three turns; and, being
aided by its friction upon the wood, he both prevents it from slipping
backwards, and uncoils each turn as it is progressively made.

Mr. Hindmarsh, master mariner of Newcastle, obtained a patent, in
February, 1827, for a contrivance to enable a capstan or windlass to be
occasionally worked with increased mechanical advantage. With this view,
he placed toothed wheel-work, partly in the drum-head of the capstan,
and partly in the upper part of the barrel, upon which the cable is
coiled and uncoiled in successive portions.

The drum-head, and also the barrel, turn loosely upon a central spindle,
independent of each other, and are connected together either by the
toothed geer, or by bolts. On raising or withdrawing the connecting
pinion from the toothed wheels, and then locking the drum-head and
barrel together, the capstan works with a power equal only to that
exerted by the men at the capstan-bars, as an ordinary capstan; but on
lowering the pinion into geer with the wheel-work, and withdrawing the
bolts which locked the drum-head to the barrel, the power exerted by the
men becomes increased in proportion to the diameter and numbers of teeth
in the wheels and pinions.

[Illustration: 255 256]

_Fig._ 255. is the external appearance of this capstan. _Fig._ 256. a
horizontal view of the toothed geer at the top of the barrel. The
barrel, with the whelps _a a_, turns loosely upon a verticle spindle
fixed into the deck of the vessel. The drum-head _b_ also turns loosely
upon the same spindle. The circular frame _c c_, in _fig._ 256., in
which the axes of the toothed wheels _d d d_ are mounted, is fixed to
the central spindle. The rim _e e e_, with internal teeth, is made fast
to the top of the barrel; and the pinion _f_, which slides upon the
spindle, is connected to the drum-head.

When it is intended to work the capstan with ordinary power, the pinion
_f_ is raised up into the recess of the drum-head, by means of a screw
_g_, _fig._ 255., which throws it out of geer with the toothed wheels,
and it is then locked up by a pin _z_: the bolts _h h_ are now
introduced, for the purpose of fastening the drum-head and barrel
together, when it becomes an ordinary capstan.

But when it is required that the same number of men shall exert a
greater power, the bolts _h_ are withdrawn, and the pinion _f_ lowered
into geer, with the toothed wheels. The rotation of the drum-head, then
carrying the pinion round, causes it to drive the toothed wheels _d d
d_; and these working into the toothed rim _e e_, attached to the
barrel, cause the barrel to revolve with an increased power.

Thus, under particular circumstances, a smaller number of men at the
capstan or windlass (which is to be constructed upon the same
principle) will be enabled to haul in the cable and anchor, or warp off
the vessel, which is an important object to be effected.

In 1819, Captain Phillips obtained a patent for certain improvements in
capstans, a part of which invention is precisely the same as this in
principle, though slightly varied in its adaptation.

James Brown, ship-rigger, in his capstan, patented in 1833, instead of
applying the moving power by handspikes, having fixed two rims of teeth
round the top of the capstan, acts upon them by a rotatory worm, or
pinions turned by a winch.

[Illustration: 257 258]

_Fig._ 257. is an elevation of this capstan, and _fig._ 258. is a
horizontal top view. a is an upright shaft, fixed firmly to the deck,
serving as an axle round which the body of the capstan revolves. A frame
_c_, fixed to the top of a stationary shaft _a_, above the body of the
capstan, carries the driving apparatus.

The upper part of the body of the capstan has a ring of oblique teeth
_d_ formed round its edge; and above this, on the top of the capstan, is
a ring of bevel teeth _e_. A horizontal shaft _f_, mounted in the top
frame _c_, has a worm or endless screw, which takes into the teeth of
the ring _d_; and a short axle _g_, having its bearings in the central
shaft _a_, and in the frame _c_, carries a bevel pinion, which takes
into the bevel teeth of the ring _c_.

The bearings of the shaft _f_, in the top frame, are in long slots, with
angular returns, something like the fastening of a bayonet, which is for
the purpose of enabling the shaft to be readily lifted in and out of
geer with the teeth of the ring _d_: the outer bearing of the axle _g_
of the bevel pinion is also supported in the frame _c_, in a similar
way, in order to put it in and out of geer with the teeth of the bevel
ring _e_. A mode of shifting these is essential; because the two toothed
rings, and their driving worm and pinion, give different speeds, and, of
course, cannot be both in operation at the same time.

The worm of the shaft _f_, being placed in geer with the teeth of the
ring _d_, on applying rotatory power thereto, by means of winches
attached to the ends of the shaft, the barrel or body of the capstan
will be made to revolve with a slow motion, but with great power; and
thus two men at the winches will do the same work as many men with
capstan bars in the ordinary way.

If a quicker movement than that of the endless screw is desired, then
the driving power may be applied by a winch to the axle _g_ of the bevel
pinion, that pinion being put into geer with the bevel ring _e_, and the
endless screw withdrawn. It should, however, be here remarked, that the
patentee proposes to employ two short axles _g_, placed opposite to each
other, with bevel pinions acting in the bevel-toothed ring, though only
one is shown in the figure to avoid confusion. He also contemplates a
modification of the same contrivance, in which four short axles _g_,
placed at right angles, with pinions taking into a bevel ring, may be
employed, and made effective in giving rotatory motion to the barrel of
a capstan by means of winches applied to the outer ends of the axle, and
turned by the labour of four men.


CARAT or CARACT is a weight used by goldsmiths and jewellers. See ASSAY
and DIAMOND.


CARBON, (_Carbone_, Fr.; _Kohlenstoff_, Germ.) in a perfectly pure
state, constitutes diamond. Carbonaceous substances are usually more or
less compound, containing hydrogen, or sometimes oxygen, and azote,
along with earthy and metallic matters. Carbon, tolerably pure, abounds
in the mineral kingdom; and, in a combined state, it forms a main
constituent of vegetable and animal bodies. Anthracite is a mineral
charcoal, differing from common pit-coal in containing no bitumen, and,
therefore, burning without flame or smoke. _Coke_ is the carbonaceous
mass which remains after pit-coal has been exposed to ignition for some
time out of contact of air; its volatile parts having been dissipated by
the heat. It is a spongy substance, of an iron-black colour, a somewhat
metallic lustre, and does not easily burn unless several pieces are
kindled together. With a good draught, however, it produces a most
intense heat. _Wood charcoal_ is obtained by the calcination of wood in
close vessels, as described under the article ACETIC ACID, or in piles
of various shapes, covered with loam, to screen it from the free action
of the atmosphere, which would otherwise consume it entirely. See
CHARCOAL. Such carbon is a solid, without smell or taste, and bears the
strongest heats of our furnaces without suffering any change, provided
air be excluded: it is a bad conductor of heat, but conducts electricity
very well. When burned, it unites with oxygen, and forms carbonic acid,
the fixed air of Dr. Black, the choke-damp of the miner. When this
carbonic acid is made to traverse red hot charcoal it dissolves a
portion of it, and becomes carbonic oxide, which contains only one half
of its volume of oxygen; whereas carbonic acid consists of one volume of
oxygen combined with one volume of the vapour of carbon, the two being
condensed into one volume. If the specific gravity of oxygen, = 1·1025,
be deducted from that of carbonic acid, = 1·5245, the difference, =
0·422, will be the specific gravity of the vapour of carbon; as well as
the proportion present in that weight of the acid.

[Illustration: 259 260 261 262]

Charcoal obtained by the action of a rapid fire in close vessels is not
so solid and so good a fuel as that which is made in the ancient way by
the slow calcination of pyramidal piles covered with earth. One of the
most economical ovens for making wood charcoal is that invented by M.
Foucauld, which he calls a _shroud_, or _abri_. To construct one of
these, 30 feet in diameter at the base, 10 feet at its summit, and from
8 to 9 feet high, he forms, with wood 2 inches square, a frame 12 feet
long, 3 feet broad at one end, and one foot at the other. The figure
will explain the construction. The uprights, A B and C D, of this frame
are furnished with three wooden handles _a a a_, and _a´ a´ a´_, by
means of which they can be joined together, by passing through two
contiguous handles a wooden fork, the frame being previously provided
with props, as shewn in _fig._ 259, and covered with loam mixed with
grass. A flat cover of 10 feet diameter, made of planks well joined, and
secured by four cross bars, is mounted with two trap doors, M N, _fig._
261., for giving egress to the smoke at the commencement of the
operation; a triangular hole P, cut out in the cover, receives the end
of a conduit Q R S, (_figs._ 262. and 261.) of wood formed of three
deals, destined to convey the gases and condensed liquids into the casks
F G H. Lastly, a door T, which may be opened and shut at pleasure,
permits the operator to inspect the state of the fire. The charcoal
calcined by this _abri_, has been found to be of superior quality.

When it is wished to change the place where the _abri_ is erected, and
to transport it to a store of new-felled timber, the frame is taken
down, after beating off the clay which covers it, the joints are then
cut by a saw, as well as the ends of the forks which fixed the frames to
one another. This process is economical in use, simple and cheap in
construction; since all the pieces of the apparatus are easily moved
about, and may be readily mounted in the forests. For obtaining a
compact charcoal, for the use of artisans, this mixed process of
Foucauld is said to be preferable to either the close iron cylinder or
the pile.

For making gunpowder-charcoal the lighter woods, such as the willow,
dogwood, and alder answer best; and in their carbonization care should
be taken to let the vapours freely escape, especially towards the end of
the operation, for when they are re-absorbed, they greatly impair the
combustibility of the charcoal.

By the common process of the forests, about 18 per cent. of the weight
of the wood is obtained; by the process of Foucauld about 24 per cent.
are obtained, with 20 of crude pyrolignous acid of 10 degrees Baumé. By
the process described under ACETIC ACID, 27 of charcoal, and 18 of acid
at 6 degrees, are procured from 100 parts of wood, besides the tar.
These quantities were the results of careful experimenting, and are
greater than can be reckoned upon in ordinary hands.

Charcoal for chemical purposes may be extemporaneously prepared by
calcining pieces of wood covered with sand in a crucible, till no more
volatile matter exhales.

The charcoal of some woods contains silica, and is therefore useful for
polishing metals. Being a bad conductor of heat, charcoal is employed
sometimes in powder to encase small furnaces and steam-pipes. It is not
affected by water; and hence, the extremities of stakes driven into
moist ground are not liable to decomposition. In like manner casks when
charred inside preserve water much better than common casks, because
they furnish no soluble matter for fermentation or for food to
animalcules.

Lowitz discovered that wood charcoal removes offensive smells from
animal and vegetable substances, and counteracts their putrefaction. He
found the odour of succinic and benzoic acids, of bugs, of empyreumatic
oils, of infusions of valerian, essence of wormwood, spirits distilled
from bad grain, and sulphureous substances were all absorbable by
freshly calcined charcoal properly applied. A very ingenious filter has
been constructed for purifying water, by passing it through strata of
charcoal of different fineness.

When charcoal is burned, one third of the heat is discharged by
radiation, and two thirds by conduction.

The following table of the quantity of charcoal yielded by different
woods was published by Mr. Mushet, as the result of experiments
carefully made upon the small scale. He says, the woods before being
charred were thoroughly dried, and pieces of each kind were selected as
nearly alike in every respect as possible. One hundred parts of each
sort were taken, and they produced as under:--

  Lignum Vitæ afforded 26·0 of charcoal of a greyish colour, resembling
                            coke.
  Mahogany             25·4 tinged with brown, spongy and porous.
  Laburnam             24·5 velvet black, compact, very hard.
  Chesnut              23·2 glossy black, compact, firm.
  Oak                  22·6 black, close, very firm.
  Walnut               20·6 dull black, close, firm.
  Holly                19·9 dull black, loose and bulky.
  Beech                19·9 dull black, spongy, firm.
  Sycamore             19·7 fine black, bulky, moderately firm.
  Elm                  19·5 fine black, moderately firm.
  Norway Pine          19·2 shining black, bulky, very soft.
  Sallow               18·4 velvet black, bulky, loose and soft.
  Ash                  17·9 shining black, spongy, firm.
  Birch                17·4 velvet black, bulky, firm.
  Scottish Pine        16·4 tinged with brown, moderately firm.

Messrs. Allen and Pepys, from 100 parts of the following woods, obtained
the quantities of charcoal as under:--

  Beech           15·00
  Mahogany        15·75
  Lignum Vitæ     17·25
  Oak             17·40
  Fir             18·17
  Box             20·25

It is observable that the quantities obtained by Messrs. Allen and Pepys
are in general less than those given by Mr. Mushet, which may be owing
to Mr. Mushet not having applied sufficient heat, or operated long
enough, to dissipate the aqueous matter of the gaseous products.

To those persons who buy charcoal by weight, it is important to purchase
it as soon after it is made as possible, as it quickly absorbs a
considerable portion of water from the atmosphere. Different woods,
however, differ in this respect. Messrs. Allen and Pepys found that by a
week’s exposure to the air, the charcoal of

  Lignum Vitæ gained      9·6 per cent.
  Fir                    13·0  ditto.
  Box                    14·0  ditto.
  Beech                  16·3  ditto.
  Oak                    16·5  ditto.
  Mahogany               18·0  ditto.

The following is a tabular view of the volumes of the different gases
which were absorbed in the course of 24 hours, by one volume of
charcoal, in the experiments of M. Theodore de Saussure, which were
conducted in a way likely to produce correct results. Each portion of
charcoal was heated afresh to a red heat, and allowed to cool under
mercury. When taken from the mercury, it was instantly plunged into the
vessel of gas.

  Ammoniacal gas           90
  Muriatic acid gas        85
  Sulphurous acid          65
  Sulphuretted hydrogen    55
  Nitrous oxide            40
  Carbonic acid gas        35
  Bicarburetted hydrogen   35·00
  Carbonic oxide            9·42
  Oxygen gas                9·25
  Nitrogen                  7·50
  Carburetted hydrogen      5·00
  Hydrogen gas              1·75

Neumann, who made many experiments on charcoal, informs us that for the
reduction of the metallic oxides, the charcoal of the heavier woods, as
that of the oak and the beech, is preferable, and that, for common fuel,
such charcoal gives the greatest heat, and requires the most plentiful
supply of air to keep it burning; while those of the lighter woods
preserve a glowing heat with a much less draught of air; and that for
purposes where it is desirable to have a steady and a still fire,
charcoal should be employed which has been made from wood previously
divested of its bark, since it is the cortical part which crackles and
flies off in sparks during combustion, while the coal of the wood itself
seldom does.

For making crayons of charcoal, the willow is the best wood that can be
employed, as the softness is uniform in all its parts. Its durability
may be seen in several of our old churchyards, where the letters made
with lamp-black are still perfect, though the white lead with which the
body of the stones was painted is entirely destroyed.

This property of carbon is shewn, however, in a more striking manner by
the writings that were found in the ruins of Herculaneum, which have
retained their original blackness for two thousand years. The ancients
wrote with ink made from ground charcoal.

If it be required to purify any carbonaceous matter, to render it fitter
for delicate pigments, this may be done by first calcining it in a close
vessel, and then lixiviating it in water slightly acidulated by nitric
acid.

The incorruptibility of charcoal was well known to the ancients, and
they availed themselves of this property upon all important occasions.

About sixty years ago a quantity of oak stakes were found in the bed of
the Thames, in the very spot where Tacitus says that the Britons fixed a
vast number of such stakes, to prevent the passage of Julius Cæsar and
his army. These stakes were charred to a considerable depth, had
retained their form completely, and were firm at the heart.

Most of the houses in Venice stand upon piles of wood, which have all
been previously charred for their preservation. In this country, estates
were formerly marked out by charred stakes driven to a considerable
depth into the ground. See BONE-BLACK, CHARCOAL, and GRAPHITE.


CARBONATED WATER, is water either pure, or holding various saline
matters in solution, impregnated with carbonic acid gas. For general
sale in this country, the water usually contains a little soda, which
being charged with the gas, is called _Soda water_; see this article for
a description of an excellent machine for the manufacture of this
fashionable beverage.


CARBONATES. Saline compounds in definite proportions, of carbonic acid,
with alkalis, earths, and the ordinary metallic oxides.

The carbonates principally used in the arts and manufactures are those
of _ammonia_, _copper_, _iron_, _lead_, _lime_, _magnesia_, _potash_,
_soda_. Native carbonate of copper is the beautiful green mineral called
Malachite.

Carbonates are easily analyzed by estimating either by weight or measure
the quantity of carbonic acid which they evolve under the decomposing
action of somewhat dilute sulphuric, nitric, or muriatic acid; for as
they are all compounds of acid, and base in equivalent proportions, the
quantity of acid will indicate the quantity of base. Thus, as pure
limestone consists of 56 of lime and 44 of acid, in 100 parts, if upon
examining a sample of limestone we find it to give out only 22 per cent.
of carbonic acid gas, during its slow solution in muriatic acid, we are
sure that there are only 28 parts of lime present. I have described, in
the Annals of Philosophy, for October, 1817, a simple form of apparatus
for analyzing the carbonates with equal readiness and precision. The
simple rule by _measure_ to which I was led, may be thus stated: _From
the bulk of evolved gas, expressed in cubic inches and tenths, deduct
1/20, the remainder will express the proportion of real limestone
present in the grains employed._ Pure magnesian limestone yields very
nearly a cubic inch of the gas for every grain in weight.


CARBONATE OF AMMONIA. A salt called in modern chemistry
_sesquicarbonate_, to denote its being composed of one and a half
equivalent primes of carbonic acid, and one of ammonia. It consists by
my analysis of 55·89 carbonic acid, 28·86 ammonia, and 15·25 water, in
100 parts. It is generally prepared by mixing from 1-1/4 to 1-1/2 parts
of well-washed dry chalk, with 1 of sal-ammoniac, introducing the
mixture into an earthen or cast-iron retort, or subliming pot, and
exposing it to a heat gradually raised to redness. By double
decomposition, the ammonia is volatilized in combination with the
carbonic acid of the chalk, and the vapours are received in a condensing
receiver made either of glass, stone ware, or lead. The chlorine of the
sal-ammoniac remains in the retort, associated with the basis of the
chalk in the state of chloride of calcium. Some ammonia gas escapes
during the process.

The saline mass thus sublimed is purified by a second sublimation in
glass, or salt-glazed earthen vessels. The salt may be obtained, by the
above method carefully conducted, in rhomboidal octahedrons, but it is
generally made for the market in a compact semi-crystalline white cake.
It has a pungent ammoniacal smell, a hot, pungent, alkaline taste, a
strong alkaline reaction, and dissolves in two parts of cold water. It
must be kept in well-closed vessels, as by exposure to the air a portion
of its ammonia exhales, and it passes into the state of the scentless
bi-carbonate. It is employed much in medicine, chemical analysis, and by
the pastry-cooks to give sponginess to their cakes in consequence of its
volatilization from their dough in the oven. See SAL-AMMONIAC.

For the other carbonates used in the arts, see their respective bases;
copper, lead, lime, &c.


CARBONIC ACID (_Acide carbonique_, Fr.; _Kohlensäure_, Germ.), consists
of 1 prime equivalent of carbon = 6·125 + 2 of oxygen = 16·026, whose
joint sum = 22·151, represents the atomic weight or combining ratio of
this acid, in the neutral or protocarbonate salts. Its composition by
volume is stated under CARBON. Its natural form is a gas, whose specific
gravity is 1·5245, compared to atmospheric air 1·000; and being so
dense, it may be poured out of one vessel into another. Hence it was
called at first _aërial acid_. From its existing copiously, in a solid
state, in limestones and the mild alkalies, it was styled _fixed air_ by
its proper discoverer, Dr. Black. About one volume of it exists in 1000
volumes of common atmospheric air, which may be made manifest by the
crust of carbonate it occasions upon the surface of lime water. Carbonic
acid gas is found accumulated in many caverns of volcanic districts, and
particularly in the _grotto dei cani_ at Pausilippo, near Puzzuoli;
being disengaged in such circumstances by the action of subterranean
fire, and, possibly, of certain acids, upon the limestone strata. It
often issues from fountains in copious currents, as at Franzensbrunn,
near Eger, in Polterbrunnen; near Trier; and Byrreshorn. This acid gas
occurs also frequently in mines and wells, being called _choke damp_,
from its suffocating quality. Its presence may, at all times, be
detected, by letting down a lighted candle, suspended from a string,
into the places suspected of containing this mephitic air. It exists, in
considerable quantities, in the water of every pump well, and gives it a
fresh and pleasant taste. Water, exposed some time to the air, loses
these aerial particles, and becomes vapid. Many springs are highly
impregnated with carbonic acid gas, and form a sparkling beverage; such
as the _Selterswasser_, from Selters upon the Lahn, in the grand duchy
of Nassau; of which no less than two millions and a half of bottles are
sold every year. A prodigious quantity of a similar water is also
artificially prepared in Great Britain, and many other countries, under
the name of aërated or soda water.

Carbonic acid occurs in nature, combined with many salifiable bases; as
in the carbonates of soda, baryta, strontia, magnesia; the oxides of
iron, manganese, zinc, copper, lead, &c. From these substances it may be
separated, generally speaking, by strong ignition, or, more readily, by
the superior affinity of muriatic, sulphuric, or nitric acid, for the
earth or metallic oxide. It is formed whenever vegetable or animal
substances are burned with free access of air, from the union of their
carbonaceous principle with atmospheric oxygen. It is also formed in all
cases of the spontaneous decomposition of organic substances,
particularly in the process of fermentation; and constitutes the
pungent, noxious, heavy gas thrown off, in vast volumes, from beer vats.
See DISTILLATION and FERMENTATION. Carbonic acid is also generated in
the breathing of animals; from 4 to 5 per cent., in volume, of the
inhaled oxygen being converted, at each expiration, into this gas, which
contaminates the air of crowded apartments, and renders ventilation
essential to health, and even to life: witness the horrible catastrophe
of the Black-hole at Calcutta.

Carbonic acid gas is destitute of colour, has a sourish, suffocating
smell, an acidulous pungent taste, imparts to moist, but not dry, litmus
paper, a transient reddish tint, and weighs per 100 cubic inches, 46-1/2
grains; and per cubic foot, 803-1/2 grains; a little more than 3-3/4 oz.
avoirdupoid. A cubic foot of air weighs about two thirds of that
quantity, or 527 grains. It may be condensed into the liquid state by a
pressure of 40 atmospheres, and this liquid may be then solidified by
its own sudden spontaneous evaporation. If air contain more than 15 per
cent. in bulk of this gas, it becomes unfit for respiration and
combustion, animal life and candles being speedily extinguished by it.

Before a person ventures into a deep well, or vault containing
fermenting materials, he should introduce a lighted candle into the
space, and observe how it burns. Carbonic acid, being so much denser
than common air, may be drawn out of cellars or fermenting tubs, by a
pump furnished with a leather hose, which reaches to the bottom.
Quicklime, mixed with water, may be used also to purify the air of a
sunk apartment by its affinity for, or power of, absorbing this aërial
acid. See MINERAL WATERS and SODA WATER.


CARBONIC OXIDE. See the article CARBON.


CARBUNCLE. A gem highly prized by the ancients; most probably a variety
of the noble garnet of modern mineralogists.


CARBURET OF SULPHUR, called also sulphuret of carbon, and alcohol of
sulphur, is a limpid volatile liquid, possessing a penetrating fetid
smell, and an acrid burning taste. Its specific gravity is 1·265; and
its boiling point is about 112° Fahr. It evaporates so readily, and
absorbs so much heat in the vaporous state, that if a tube containing
quicksilver, surrounded with lint dipped in this liquid, be suspended in
the receiver of an air-pump, on making the vacuum, the quicksilver will
be congealed. It consists of 15·8 carbon and 84·2 sulphur, in 100 parts;
being two equivalent primes of the latter to one of the former.


CARBURETTED HYDROGEN. A compound of carbon and hydrogen, of which there
are several species--such as oil-gas, coal-gas, olefiant gas, oil of
lemons, otto of roses, oil of turpentine, petroleum, naphta,
naphthaline, oil of wine, caoutchoucine and caoutchouc.


CARDS, PLAYING. (_Cartes à jouer_, Fr.; _Karten_, Germ.) Mr. de la Rue
obtained, in February, 1832, a patent for certain improvements in the
manufacture of playing cards, which he distributed under three heads:
first, printing the pips, and also the picture or court-cards, in oil
colours by means of types or blocks; secondly, effecting the same in oil
colours by means of lithography; and thirdly, gilding or silvering
borders, and other parts of the characters, by the printing process,
either by types, blocks, or lithography.

In the ordinary mode of manufacturing playing cards, their devices are
partly produced by copperplate printing, and they are filled up with
water colours by the means called stencilling.

The patentee does not propose any material alteration in the devices or
forms upon the cards, but only to produce them with oil colours; and, to
effect this, he follows precisely the same mode as that practised by
calico printers.

A set of blocks or types properly devised, are produced for printing the
different pips of hearts, diamonds, spades, and clubs, or they are
drawn, as other subjects, in the usual way upon stone. The ink or
colour, whether black or red, is to be prepared from the best French
lamp-black, or the best Chinese vermillion ground in oil, and laid on
the types and blocks, or on the stone, in the same way as printers’ ink,
and the impressions taken-on to thick drawing paper by means of a
suitable press in the ordinary manner of printing.

The picture or court-cards are to be produced by a series of impressions
in different colours, fitting into each other exactly in the same way as
in printing paper hangings, or silks and calicoes, observing that all
the colours are to be prepared with oil.

For this purpose a series of blocks or types are to be provided for each
subject, and which, when put together, will form the whole device. These
blocks are to be used separately, that is, all the yellow parts of the
picture, for instance, are to be printed at one impression, then all the
red parts, next all the flesh colour, then the blue portions, and so on,
finishing with the black outlines, which complete the picture.

If the same is to be done by lithography, there must be as many stones
as there are to be colours, each to print its portion only; and the
impression, or part of the picture given by one stone, must be exactly
fitted into by the impression given from the next stone, and so on until
the whole subject is complete.

A superior kind of card is proposed to be made, with gold or silver
devices in parts of the pictures, or gold or silver borders round the
pips. This is to be effected by printing the lines which are to appear
as gold or silver, with gilders’ size, in place of ink or colour; and
immediately after the impression has been given, the face of the card is
to be powdered over with gold dust, silver, or bronze, by means of a
soft cotton or wool dabber, by which the gold, silver, or bronze will be
made to adhere to the picture, and the superfluous portions of the metal
will wipe off by a very slight rubbing. When the prints are perfectly
dry, the face of the card may be polished by means of a soft brush.

If it should be desirable to make these improved cards to resemble
ivory, that may be done by preparing the face of the paper in the first
instance with a composition of size and fine French white, and a drying
oil, mixed together to about the consistence of cream; this is to be
washed over the paper, and dried before printing, and when the cards are
finished, they will exactly resemble ivory.

The only thing remaining to be described, is the means by which the
successive impressions of the types, blocks, or stones forming the parts
of the pictures, are to be brought exactly to join each other, so as to
form a perfect whole design when complete; this is by printers called
registering, and is to be effected much in the usual way, by points in
the tympan of the press, or by marks upon the stones.

The parts of the subject having been all accurately cut or drawn to fit,
small holes are to be made with a fine awl through a quire or more of
the paper at once, by placing upon the paper a gauge-plate, having marks
or guide-holes, and by observing these, the same sheet laid on several
times, and always made to correspond with the points or marks, the
several parts of the picture must inevitably register, and produce a
perfect subject.


CARD CUTTING. Mr. Dickinson’s patent machine for cutting cards, consists
of a pair of rollers with circular revolving cutters, the edges of which
are intended to act against each other as circular shears, and the
pasteboards in passing between these rollers are cut by the circular
shears into cards of the desired dimensions. These rollers are mounted
in suitable standards, with proper adjustments, and are made to revolve
by a band and pulley connected to the axle of a crank, or by any other
convenient means.

[Illustration: 263 264 265 266]

_Fig._ 263. is a front view of this machine; _a a_ and _b b_ are the two
rollers, the upper one turning upon an extended axle, bearing in the
standards, the lower one upon pivots. These rollers are formed by a
series of circular blocks, between a series of circular steel cutters,
which are slidden on to iron shafts, and held together upon their axle
by nuts screwed up at their ends. The accurate adjustment of the cutters
is of the first importance to their correct performance; it is therefore
found necessary to introduce spiral springs within the blocks, in order
to press the cutters up to their proper bearings. A section of one of
the blocks is shewn at _fig._ 265, and an end view of the same at _fig._
266, with the spiral springs inserted.

At the outer extremity of the axle of the roller _a_, a rigger _c_, is
attached, whence a band passes to a pulley _d_, on the crank shaft _e_,
to which a flywheel _f_, is affixed, for the purpose of rendering the
action uniform. Rotatory motion being given to the crank shaft, the
upper roller is turned, the lower roller moving at the same time by the
friction against the edges of the cutters.

_Fig._ 264 is an end view of the rollers, showing the manner in which
the pasteboards are guided and conducted between the cutters. In the
front of the machine a movable frame _g_, is to be placed, for the
purpose of receiving the pasteboards, preparatory to cutting them into
cards, and a stop is screwed to this frame for the edge of the
pasteboard to bear against, which stop is adjustable to suit different
sizes. From the back part of this frame an arm _h_, extends, the
extremity of which acts against the periphery of a ratchet wheel _i_,
fixed at the end of the roller _b_, and hence, as the roller goes round,
the frame is made to rise and fall upon its pivots, for the purpose of
guiding the pasteboard up to the cutters; at the same time a rod _k_,
hanging in arms from the sides of the standards (shewn by dots in _fig._
263), falling upon the pasteboard, confines it, while the cutters take
hold, and racks, corresponding with the indentations of the rollers, are
placed as at _l l_, by means of which the cards, when cut, are pushed
out of the grooves.

As various widths of cards will require to be cut by this machine, the
patentee proposes to have several pairs of rollers ready adjusted to act
together, when mounted in the standards, in preference to shifting the
circular cutters, and introducing blocks of greater or less width.

The second part of the invention is a machine for pasting the papers,
and pressing the sheets together to make pasteboard. This machine
consists of several reels (we suppose rollers are intended) on which the
paper is to be wound, along with a paste trough, and rotatory brushes.
The several parts of this machine, and their operations in making
pasteboard, are described in the specification, but the patentee having
omitted the letters of reference in the drawing which he has enrolled,
it becomes difficult to explain it.

As far as we are enabled to understand the machine, it appears, that
damped paper is to be wound upon two rollers, and conducted from thence
over two other rollers; that two fluted rollers revolving in the paste
trough are to supply paste to two circular brushes, and that by those
brushes the papers are to be pasted upon one side, and then pressed
together, to make the pasteboard; after this, the pasteboard is to be
drawn on to a table, and to remain there until sufficiently dry to be
wound upon other rollers. By comparing this description with the figure,
perhaps the intended operations of the machine may be discovered, it is
the best explanation we are enabled to give.


CARDS, (_Cardes_, Fr.; _Karden_, Ger.) are instruments which serve to
disentangle the fibres of wool, cotton, or other analogous bodies, to
arrange them in an orderly lap or fleece, and thereby prepare them for
being spun into uniform threads. The fineness and the levelness of the
yarn, as well as the beauty of the cloth into which it enters, depend
as much upon the regularity and perfection of the carding, as upon any
subsequent operations of the factory. The quality of the carding depends
more upon that of the cards than upon any attention or skill in the
operative; since it is now nearly an automatic process, conducted by
young women called card-tenters.

Cards are formed of a sheet or fillet of leather pierced with a
multitude of small holes, in which are implanted small staples of wire
with bent projecting ends called _teeth_. Thus every piece of wire is
double toothed. The leather is afterwards applied to a flat or
cylindrical surface of wood or metal, and the co-operation of two or
more such surfaces constitutes a card. The teeth of cards are made
thicker or slenderer, according as the filaments to be carded are
coarser or finer, stiffer or more pliant, more valuable or cheaper. It
is obviously of great importance that the teeth should be all alike,
equably distributed, and equally inclined over the surface of the
leather, a degree of precision which is scarcely possible with handwork.
To judge of the difficulty of this manipulation we need only inspect the
annexed figures. The wire must first be bent at right angles in _c_ and
_d_, _fig._ 268, then each branch must receive a second bend in _a_ and
_b_ at a determinate obtuse angle, invariable for each system of cards.
It is indispensable that the two angles _c a e_ and _d b f_ be
mathematically equal, not only as to the twin teeth of one staple, but
through the whole series; for it is easy to see that if one of the teeth
be more or less sloped than its fellow, it will lay hold of more or less
wool than it, and render the carding irregular. But though the perfect
regularity of the teeth be important, it is not the sole condition
towards making a good card. It must be always kept in view that these
teeth are to be implanted by pairs in a piece of leather, and kept in it
by the cross part _c d_. The leather must therefore be pierced with twin
holes at the distance _c d_; and pierced in such a manner, that the
slope of the holes, in reference to the plane of the leather, be
invariably the same; for otherwise the length of the teeth would vary
with this angle of inclination, and the card would be irregular.

[Illustration: 267 268 269]

A third condition essential towards producing perfect regularity, is
that the leather ought to be of the same thickness throughout its whole
surface, otherwise the teeth, though of the same length and fixed at the
same angle, would be rendered unequal by the different thicknesses of
the leather, and the operation of carding would be in consequence
extremely defective. _Fig._ 267. shows the card-teeth acting against
each other, as indicated by the arrows in two opposite directions; in
_fig._ 269. they work one way.

Of late years very complex but complete and well-acting machines have
been constructed for splitting the leather or equalizing it by shaving,
for bending and cutting the wires, and implanting them in the leather,
into holes pierced with perfect regularity. Card machines which fashion
the teeth with great precision and rapidity, and pierce the leather,
have been for a considerable time in use at Halifax, in Yorkshire, a
town famous for the excellence of its card-cloth, as also at Leeds,
Glasgow, and several other places. The wires and the leather thus
prepared are given out by the manufacturer to women and children, who
put them together.

1. The simplest machine for equalizing the leather which can be
employed, is that which I saw operating in MM. Scrive’s automatic card
factory at Lille, the most magnificent I believe in the world, where the
leather was drawn forwards by a roller over a solid horizontal table, or
bed, and passed under a nicely adjusted vertical blade, which shaved it
by a scraping motion to a perfectly uniform thickness. About one half
the weight of the leather is lost in this process, and in the subsequent
squaring and trimming.

The machine for making cards, invented I believe by a Mr. Ellis of the
United States, for which a first patent was obtained in this country by
Joseph Cheeseborough Dyer, Esq. of Manchester, in 1811, and a second and
third with further improvements in 1814, and 1824, is one of the most
elegant automatons ever applied to productive industry. It is however
necessarily so complicated with different mechanisms as to render its
representation impracticable in such engravings as are compatible with
the scope of this dictionary. I must therefore content myself with the
following general description of its constituent parts.

The first thing to be done after having, as above, prepared the long
sheets or fillets of leather, of suitable length, breadth, and
thickness, for making the cards, is to stretch the leather, and hold it
firmly; which is accomplished by winding the fillet of leather upon the
roller or drum, like the warp roller of a loom, and then conducting it
upwards between guide rollers, to a receiving or work roller at top of
the machine, where the fillet is held fast by a cramp, by which means
the leather is kept stretched.

Secondly, the holes are pierced in the leather to receive the wire
staples or teeth of the card, by means of a sliding fork, the points of
which are presented to the face of the leather; while the fork is made
to advance and recede continually, by the agency of levers worked by
rotatory cams upon a revolving main shaft.

The points of the fork being thus made to penetrate into the leather,
the holes for receiving the staples are pierced, at regular distances,
and in correct order, by shifting the leather fillet so as to bring
different parts of its surface opposite to the points of the sliding
fork. This is done by cams, or indented wheels and gear, which shift the
guide rollers and confining drums laterally, as they revolve, and
consequently move the fillet of leather at intervals a short distance,
so as to present to the points of the fork or piercer at every movement,
a different part of the surface of the leather.

Thirdly, the wire of which the teeth or points of the card are to be
made, is supplied from a coil on the side of the machine, and is brought
forward at intervals, by a pair of sliding pincers, which are slidden to
and fro through the agency of levers actuated by rotatory cams upon the
main shaft. The pincers having advanced a distance equal to the length
of wire intended to form one staple, or two points, this length of wire
is pressed upon exactly in the middle by a square piece of steel, and
being there confined, a cutter is brought forward, which cuts it off
from that part of the wire held in the pincers.

The length of wire thus separated and confined, is now, by a movement of
the machine, bent up along the sides of the square steel holder, and
shaped to three edges of the square, that is, formed as a staple; and in
the same way, by the continued movements of the machine, a succession of
pieces of wire are cut off, and bent into staples for making the teeth
of the card as long as the mechanism is kept in action.

Fourthly, the wire staple thus formed is held with its points or ends
outwards, closely contiguous to the forked piercer described above, and
by another movement of the mechanism, the staple is protruded forward,
its end entering into the two holes made previously in the leather by
the sliding of the fork.

While the wire staple is being thus introduced into the leather, its
legs or points are to be bent, that is, formed with a knee or angle,
which is the fifth object to be effected. This is done by means of a
small apparatus consisting of a bar or bed, which bears up against the
under side of the wire staple when it has been passed half-way into the
holes in the leather, and another bar above it, which being brought down
behind the staple, bends it over the resisting bar to the angle
required; that is, forms the knee in each leg. A pusher now acts behind
the staple, and drives it home into the leather, which completes the
operation.

The leather being thus conducted, and its position shifted before the
piercer progressively, a succession of the above described operations of
cutting the wire, forming the staple, passing it into the leather, and
bending its legs to the angular form, produces a sheet of card of the
kind usually employed for carding or combing wool, cotton, and other
fibrous materials. It may be necessary to add, that as these wire
staples are required to be set in the leathers sometimes in lines
crossing the sheet, which is called ribbed, and at other times in
oblique lines, called twilled, these variations are produced by the
positions of the notches or steps upon the edge or periphery of the cam
or indented wheel, which shifts the guide rollers that hold the fillet
or sheet of leather as already described.


CARMINE, (Eng. and Fr.; _Karminstoff_, Ger.), is, according to Pelletier
and Caventou, a triple compound of the colouring substance, and an
animal matter contained in cochineal, combined with an acid added to
effect the precipitation. The preparation of this article is still a
mystery, because upon the one hand, its consumption being very limited,
few persons are engaged in its manufacture, and upon the other, the raw
material being costly, extensive experiments on it cannot be
conveniently made. Success in this business is said to depend not a
little upon dexterity of manipulation, and upon knowing the instant for
arresting the further action of heat upon the materials.

There is sold at the shops different kinds of carmine, distinguished by
numbers, and possessed of a corresponding value. This difference depends
upon two causes, either upon the proportion of alumina added in the
precipitation, or of a certain quantity of vermillion put in to dilute
the colour. In the first case the shade is paler, in the second, it has
not the same lustre. It is always easy to discover the proportion of the
adulteration. By availing ourselves of the property of pure carmine to
dissolve in water of ammonia, the whole foreign matter remains
untouched, and we may estimate its amount by drying the residuum.

_To make Ordinary Carmine._

  Take 1 pound of cochineal in powder;
       3 drachms and a half of carbonate of potash;
       8 drachms of alum in powder;
       3 drachms and a half of fish-glue.

The cochineal must be boiled along with the potash in a copper
containing five pailfuls of water (60 pints); the ebullition being
allayed with cold water. After boiling a few minutes the copper must be
taken from the fire, and placed on a table at such an angle as that the
liquor may be conveniently transvased. The pounded alum is then thrown
in, and the decoction is stirred; it changes colour immediately, and
inclines to a more brilliant tint. At the end of fifteen minutes the
cochineal is deposited at the bottom, and the bath becomes as clear as
if it had been filtered. It contains the colouring matter, and probably
a little alum in suspension. We decant it then into a copper of equal
capacity, and place it over the fire, adding the fish-glue dissolved in
a great deal of water, and passed through a searce. At the moment of
ebullition, the carmine is perceived to rise up to the surface of the
bath, and a coagulum is formed, like what takes place in clarifications
with white of egg. The copper must be immediately taken from the fire,
and its contents be stirred with a spatula. In the course of fifteen or
twenty minutes the carmine is deposited. The supernatant liquor is
decanted, and the deposit must be drained upon a filter of fine canvas
or linen. If the operation has been well conducted, the carmine when dry
crushes readily under the fingers. What remains after the precipitation
of the carmine is still much loaded with colour, and may be employed
very advantageously for carminated lakes. See LAKE.

By the _old German process_ carmine is prepared by means of alum without
any other addition. As soon as the water boils the powdered cochineal is
thrown into it, stirred well, and then boiled for six minutes; a little
ground alum is added, and the boiling is continued for three minutes
more; the vessel is removed from the fire, the liquor is filtered and
left for three days in porcelain vessels, in the course of which time a
red matter falls down, which must be separated and dried in the shade.
This is carmine, which is sometimes previously purified by washing. The
liquor after three days more lets fall an inferior kind of carmine, but
the residuary colouring matter may also be separated by the muriate of
tin.

The proportions for the above process are 580 parts of clear river
water, 16 parts of cochineal, and 1 part of alum; there is obtained from
1-1/2 to 2 parts of carmine.

Another _carmine with tartar_.--To the boiling water the cochineal is
added, and after some time a little cream of tartar; in eight minutes
more we add a little alum, and continue the boiling for a minute or two
longer. Then take it from the fire and pour it into glass or porcelain
vessels, filter and let it repose quietly till the carmine falls down.
We then decant and dry in the shade. The proportions are 8 pounds of
water, 8 oz. of cochineal, 1/2 oz. of cream of tartar, 3/4 oz. of alum,
and the product is an ounce of carmine.

_The process of Alxon or Langlois._--Boil two pails and a half of river
water (30 pints), throw into it, a little afterwards, a pound of
cochineal, add a filtered solution of six drachms of carbonate of soda
and a pound of water, and let the mixture boil for half an hour; remove
the copper from the fire, and let it cool, inclining it to one side. Add
six drachms of pulverized alum, stir with a brush to quicken the
solution of the salt, and let the whole rest 20 minutes. The liquor,
which has a fine scarlet colour, is to be carefully decanted into
another vessel, and there is to be put into it the whites of two eggs
well beat up with half a pound of water. Stir again with a brush. The
copper is replaced on the fire, the alumina becomes concrete, and
carries down the colouring matter with it. The copper is to be taken
from the fire, and left at rest for 25 or 30 minutes to allow the
carmine to fall down. When the supernatant liquor is drawn off, the
deposit is placed upon filter cloth stretched upon a frame to drain.
When the carmine has the consistence of cream cheese, it is taken from
the filter with a silver or ivory knife and set to dry upon plates
covered with paper, to screen it from dust. A pound of cochineal gives
in this way an ounce and a half of carmine.

_Process of Madame Cenette of Amsterdam_, with salt of sorrel.--Into six
pails of river water boiling hot throw two pounds of the finest
cochineal in powder, continue the ebullition for two hours and then add
3 oz. of refined saltpetre, and after a few minutes 4 oz. of salt of
sorrel. In ten minutes more take the copper from the fire and let it
settle for four hours; then draw off the liquor with a syphon into flat
plates and leave it there for three weeks. Afterwards there is formed
upon the surface a pretty thick mouldiness, which is to be removed
dexterously in one pellicle by a slip of whalebone. Should the film tear
and fragments of it fall down, they must be removed with the utmost
care. Decant the supernatant water with a syphon, the end of which may
touch the bottom of the vessel, because the layer of carmine is very
firm. Whatever water remains must be sucked away by a pipette. The
carmine is dried in the shade, and has an extraordinary lustre.

_Carmine by the salt of tin, or the Carmine of China._--Boil the
cochineal in river water, adding some Roman alum, then pass through a
fine cloth to remove the cochineal, and set the liquor aside. It becomes
brighter on keeping. After having heated this liquor, pour into it drop
by drop solution of tin till the carmine be precipitated. The
proportions are one pailful of water, 20 oz. of cochineal and 60 grains
of alum, with a solution of tin containing 4 oz. of the metal.

_To revive or brighten carmine._--We may brighten ordinary carmine, and
obtain a very fine and clear pigment, by dissolving it in water of
ammonia. For this purpose we leave ammonia upon carmine in the heat of
the sun, till all its colour be extracted, and the liquor has got a fine
red tinge. It must be then drawn off and precipitated, by acetic acid
and alcohol, next washed with alcohol, and dried. Carmine dissolved in
ammonia has been long employed by painters, under the name of liquid
carmine.

Carmine is the finest red colour which the painter possesses. It is
principally employed in miniature painting, water colours, and to tint
artificial flowers, because it is more transparent than the other
colours. For _Carminium_, see COCHINEAL.


CARPET. (_Tapis_, Fr.; _Teppich_, Germ.) A thick woollen fabric of
variegated colours, for covering the floors of the better sort of
apartments. This luxurious manufacture took its origin in Persia and
Turkey, whence the most beautiful patterns were wont to come into
Europe; but they have been for some time surpassed by the workmanship of
France, Great Britain, and Belgium. To form a just conception of the
elegant and ingenious processes by which carpets are made, we should
visit the royal establishment of the Gobelins at Paris, where we would
see the celebrated carpet manufactory of the Savonnerie, which has been
transported thither. A detailed set of engravings of this art is given
by Roland de la Platière in the first and second volumes of the
Encyclopédie Méthodique, to which I must refer my readers, as a due
exposition of its machines and operations would far exceed the scope of
the present volume.

The warp, says M. Roland, being the foundation of the fabric, ought to
be of fine wool, equally but firmly spun, and consist of three yarns
twisted into one thread. The yarns that are to form the velvety surface
of the carpet, ought also to be of the best quality, but soft and downy
in their texture, so that the dye may penetrate every filament. Hemp, or
linen yarns, are likewise employed in this manufacture, as a woof, to
bind the warp firmly together after each shoot of the velvety threads.
Thus we see that good carpeting consists essentially of two distinct
webs woven at the same time, and firmly decussated together by the woof
threads. Hence the form of the pattern is the same upon the two sides of
the cloth, only the colours are reversed, so that what was green upon
one side becomes red or black upon the other, and _vice versâ_. The
smaller the figures the more frequent the decussations of the two
planes, and the firmer and more durable the fabric.

The carpet manufacture, as now generally practised, may be distributed
into two systems--that of double fabrics, and that cut in imitation of
velvet. Of late years the Jacquard loom has been much used in weaving
carpets, the nature of which will be found fully explained under that
title.

For the sake of illustration, if we suppose the double carpets to be
composed of only two colours, the principle of weaving will be easily
understood; for it is only necessary to raise the warp of each web
alternately for the passage of the shuttle, the upper web being entirely
above when the under web is being woven, or decussated, and _vice
versâ_. In a Brussels carpet the worsted yarn raised to form the pile,
and make the figure, is not cut; in the Wilton the pile is cut to give
it a velvety aspect and softness. In the imperial Brussels carpet the
figure is raised above the ground, and its pile is cut, but the ground
is uncut; and in the royal Wilton, the pile is both raised higher than
in the common Wilton, and it is cut, whereby it has a rich cushion-like
appearance. The cloth of all these superior carpets consists of woollen
and linen, or hemp; the latter being put upon a beam, and brought, of
course, through heddles and a reed; but as its only purpose is to bind
together the worsted fabric, it should not be visible upon the upper
face of the carpet. The worsted yarn is wound upon small bobbins or
pirns, with a weight affixed to each, for giving proper tension to the
threads. Their number varies, for one web, from 1300 to 1800, according
as the carpet is to be 27 or 36 inches wide; and, they are placed, in
frames, behind the loom, filled with differently coloured yarn, to
correspond with the figure. This worsted warp is then drawn through the
harness, heddles, and reed, to be associated with the linen yarn in the
compound fabric.

In Kidderminster carpeting, both warp and weft appear upon the face of
the cloth, whereas, in the Brussels style, only the warp is seen, its
binding weft being fine hempen or linen threads. The three-ply imperial
carpet, called the Scotch, is coming very much into vogue, and is
reckoned by many to be little inferior in texture, look, and wear to the
Brussels. Kilmarnock has acquired merited distinction by this ingenious
industry. In this fabric, as well as in the two-ply Kidderminster, the
weft predominates, and displays the design; but, in the French carpets,
the worsted warp of the web shows the figure. Plain Venetian carpets, as
used for stairs and passages, are woven in simple looms, provided merely
with the common heddles and reed. The warp should be a substance of
worsted yarn, so heavy as to cover in the weft completely from the view.
Figured Venetian carpets are woven in the two-ply Kidderminster looms,
and are provided with a mechanism to raise the pattern upon the worsted
warp. The weft is an alternate shoot of worsted and linen yarn, and must
be concealed.

[Illustration: 270]

The following figure and description will explain the construction of
the three-ply imperial Scotch and two-ply Kidderminster carpet loom,
which is merely a modification of the Jacquard _métier_. The Brussels
carpet-loom, on the contrary, is a draw-boy loom on the damask plan, and
requires the weaver to have an assistant. _Fig._ 270. A A A, is the
frame of the loom, consisting of four upright posts, with caps and cross
rails to bind them together. The posts are about six feet high. C C, the
cloth-beam, is a wooden cylinder, six inches or thereby in diameter, of
sufficient length to traverse the loom, with iron gudgeons in the two
ends, which work in bushes in the side frame. On one end of this beam is
a ratchet wheel, with a tooth to keep it from turning round backwards by
the tension of the web. D, the lay, with its reed, its under and upper
shell, its two lateral rulers or swords, and rocking-tree above. There
are grooves in the upper and under shell, into which the reed is fitted.
E, the heddles, or harness, with a double neck attached to each of the
tower or card mechanisms F F, of the Jacquard loom. The heddles are
connected and work with the treddles B B, by means of cords, as shown in
the figure. G G are wooden boxes for the cards. H, the yarn, or warp
beam.

[Illustration: 271]

In draw-looms of every kind, there is no sinking of any portion of the
warp, as in plain cloth-weaving; but the plane of the warp is placed
low, and the threads under which the shuttle is to pass are raised,
while all the rest remains stationary. The harness part of this carpet
loom is moved by an assistant boy or girl, who thus allows the weft to
be properly decussated, while the weaver attends to working the front
mounting or heddles. _Fig._ 271., A represents the frame of a carpet
draw-loom; B is a box or frame of pulleys, over which the cords of the
harness pass, and are then made fast to a piece of wood, seen at E,
which the weavers call a table. From the tail of the harness the simples
descend, and to the end of each is attached a small handle G, called a
bob. These handles being disposed in pairs, and their regularity
preserved by means of a perforated board C, it is merely necessary to
pull every handle in succession; the weaver, at the same time, working
his treddles with his feet, as in any other loom. The treddles are four
in number, the fabric being that of plain or alternate cloth, and two
treddles allotted for each web. The harness part of the carpet draw-loom
is furnished with _mails_, or metallic eyes, to save friction; two
threads being drawn through each eye. The design or pattern of a carpet
is drawn upon cross-rule paper, exactly in the same way as every other
kind of fancy-loom work, and is transferred from the paper to the
mounting by the rules for damask weaving. Suppose that a double web is
so mounted that every alternate thread of the one may be raised, so as
to form a sufficient shed-way for the shuttle, without depressing the
other in the least. Then suppose another web placed above the former, at
such a distance that it will exactly touch the convexity of those
threads of the former, which are raised. Then, if the threads of the
latter web are sunk while the others are raised, the two would be
entirely incorporated. But if this be only partially done, that is, at
particular places, only those parts immediately operated upon will be
affected by the action of the apparatus. If the carpet is a two-coloured
pattern, as black and red, and if upon the upper surface, as extended in
the loom, red flowers are to be represented upon a black ground, then
all those species of design paper which are coloured may be supposed to
represent the red, and those which are vacant the black. Then counting
the spaces upon the paper, omit those which are vacant, and cord those
which are coloured, and the effect will be produced. But as the two webs
are to be raised alternately, whatever is corded for the first handle
must be passed by for the second, and _vice versâ_; so that the one will
form the flower, and the other the ground.

The board by which the simples are regulated appears at F. D shows the
weights.


CARTHAMUS, or safflower (carthamus tinctorius), (_Carthame_, Fr.;
_Färber distel_, Germ.), the flower of which alone is used in dyeing, is
an annual plant cultivated in Spain, Egypt, and the Levant. There are
two varieties of it--one which has large leaves, and the other smaller
ones. It is the last which is cultivated in Egypt, where it forms a
considerable article of commerce.

Carthamus contains two colouring matters, one yellow and the other red.
The first alone is soluble in water; its solution is always turbid: with
re-agents it exhibits the characters usually remarked in yellow
colouring matters. The acids render it lighter, the alkalies deepen it,
giving it more of an orange hue: both produce a small dun precipitate,
in consequence of which it becomes clearer. Alum forms a precipitate of
a deep yellow, in small quantity. The solution of tin and the other
metallic solutions cause precipitates which have nothing remarkable in
them.

The yellow matter of carthamus is not employed; but in order to extract
this portion, the carthamus is put into a bag, which is trodden under
water, till no more colour can be pressed out. The flowers, which were
yellow, become reddish, and lose in this operation nearly one half of
their weight. In this state they are used.

For extracting the red part of carthamus, and thereafter applying it to
stuff, the property which alkalies possess of dissolving it is had
recourse to, and it is afterwards precipitated by an acid.

The process of dyeing consists, therefore, in extracting the colouring
matter by means of an alkali, and precipitating it on the stuff by means
of an acid. It is this fecula which serves for making the rouge employed
by ladies.

As to this rouge, the solution of carthamus is prepared with
crystallised carbonate of soda, and it is precipitated by lemon juice.
It has been remarked that lemons, beginning to spoil, were fitter for
this operation than those which were less ripe, whose juice retained
much mucilage. After squeezing out the lemon juice, it is left to settle
for some days. The precipitate of carthamus is dried at a gentle heat
upon plates of stone-ware; from which it is detached and very carefully
ground with talc, which has been reduced to a very subtile powder, by
means of the leaves of shave-grass (_presle_), and successively passed
through sieves of increasing fineness. It is the fineness of the talc,
and the greater or less proportion which it bears to the carthamus
precipitate, which constitute the difference between the high and low
priced rouges.

Carthamus is used for dyeing silk, poppy, _nacarat_ (a bright
orange-red), cherry, rose colour, and flesh colour. The process differs
according to the intensity of the colour, and the greater or less
tendency to flame colour that is wanted. But the carthamus bath, whose
application may be varied, is prepared as follows:

The carthamus, from which the yellow matter has been extracted, and
whose lumps have been broken down, is put into a trough. It is
repeatedly sprinkled with cendres gravelées (crude pearl ashes), or soda
(barilla) well powdered and sifted at the rate of 6 pounds for 120 lbs.
of carthamus; but soda is preferred, mixing carefully as the alkali is
introduced. This operation is called _amestrer_. The _amestred_
carthamus is put into a small trough with a grated bottom, first lining
this trough with a closely woven cloth. When it is about half filled, it
is placed over the large trough, and cold water is poured into the upper
one, till the lower becomes full. The carthamus is then set over another
trough, till the water comes from it almost colourless. A little more
alkali is now mixed with it, and fresh water is passed through it. These
operations are repeated till the carthamus be exhausted, when it turns
yellow.

After distributing the silk in hanks upon the rods, lemon juice, brought
in casks from Provence, is poured into the bath till it becomes of a
fine cherry colour; this is called turning the bath (_virer le bain_).
It is well stirred, and the silk is immersed and turned round the
skein-sticks in the bath, as long as it is perceived to take up the
colour. For _ponceau_ (poppy colour), it is withdrawn, the liquor is run
out of it upon the peg, and it is turned through a new bath, where it is
treated as in the first. After this it is dried and passed through fresh
baths, continuing to wash and dry it between each operation, till it has
acquired the depth of colour that is desired. When it has reached the
proper point, a brightening is given it by turning it round the sticks
seven or eight times in a bath of hot water, to which about half a pint
of lemon juice for each pailful of water has been added.

When silk is to be dyed _ponceau_ or flame colour, it must be previously
boiled as for white; it must then receive a slight foundation of
annotto, as explained in treating of this substance. The silk should not
be alumed.

The _nacarats_, and the deep cherry colours, are given precisely like
the _ponceaux_, only they receive no annotto ground; and baths may be
employed which have served for the _ponceau_, so as to complete their
exhaustion. Fresh baths are not made for the latter colours, unless
there be no occasion for the poppy.

With regard to the lighter cherry-reds, rose colour of all shades and
flesh colours, they are made with the second and last runnings of the
carthamus, which are weaker. The deepest shades are passed through
first.

The lightest of all these shades, which is an extremely delicate flesh
colour, requires a little soap to be put into the bath. This soap
lightens the colour, and prevents it from taking too speedily, and
becoming unevenly. The silk is then washed, and a little brightening is
given it, in a bath which has served for the deeper colours.

All these baths are employed the moment they are made, or as speedily as
possible, because they lose much of their colour upon keeping, by which
they are even entirely destroyed at the end of a certain time. They are,
moreover, used cold, to prevent the colour from being injured. It must
have been remarked in the experiments just described, that the caustic
alkalies attack the extremely delicate colour of carthamus, making it
pass to yellow. This is the reason why crystals of soda are preferred to
the other alkaline matters.

In order to diminish the expense of the carthamus, it is the practice in
preparing the deeper shades to mingle with the first and the second bath
about one fifth of the bath of archil.

Dobereiner regards the red colouring matter of carthamus as an acid, and
the yellow as a base. His carthamic acid forms, with the alkalies,
colourless salts, decomposed by the tartaric and acetic acids, which
precipitate the acid of a bright rose-red. Heat has a remarkable
influence upon carthamus, rendering its red colour yellow and dull.
Hence, the colder the water is by which it is extracted, the finer is
the colour. Light destroys the colour very rapidly, and hitherto no
means have been found of counteracting this effect. For this reason this
brilliant colour must be dried in the shade, its dye must be given in a
shady place, and the silk stuffs dyed with it must be preserved as much
as possible from the light. Age is nearly as injurious as light,
especially upon the dye in a damp state. The colour is very dear,
because a thousand parts of carthamus contain only five of it.

In preparing the finest rouge, the yellow colouring matter being
separated by washing with water, the red is then dissolved by the aid of
alkali, and is thrown down on linen or cotton rags by saturating the
solution with vegetable acid. The colour is rinsed out of these rags,
dissolved anew in alkalis, and once more precipitated by lemon juice.
The best and freshest carthamus must be selected. It is put into linen
bags, which are placed in a stream of water, and kneaded till the water
runs off colourless. The bags are then put into water soured with a
little vinegar, kneaded till the colour is all expelled, and finally
rinsed in running water. By this treatment the carthamus loses nearly
half its weight. 6633 cwts. of safflower were imported into the United
Kingdom in 1835, of which 2930 cwts. were retained for internal
consumption.


CASE-HARDENING, is the name of the process by which iron tools, keys,
&c., have their surfaces converted into steel.

Steel when very hard is brittle, and iron alone is for many purposes, as
for fine keys, far too soft. It is therefore an important desideratum to
combine the hardness of a steely surface with the toughness of an iron
body. These requisites are united by the process of case-hardening,
which does not differ from the making of steel, except in the shorter
duration of the process. Tools, utensils, or ornaments, intended to be
polished, are first manufactured in iron and nearly finished, after
which they are put into an iron box, together with vegetable or animal
charcoal in powder, and cemented for a certain time. This treatment
converts the external part into a coating of steel, which is usually
very thin, because the time allowed for the cementation is much shorter
than when the whole substance is intended to be converted. Immersion of
the heated pieces into water hardens the surface, which is afterwards
polished by the usual methods. Moxon in his _Mechanic Exercises_, p.
56., gives the following receipt for case-hardening:--“Cow’s horn or
hoof is to be baked or thoroughly dried and pulverised. To this add an
equal quantity of bay salt; mix them with stale chamber-lye or white
wine vinegar: cover the iron with this mixture, and bed it with the same
in loam, or enclose it in an iron box: lay it on the hearth of the forge
to dry and harden: then put it into the fire, and blow till the lump
have a blood-red heat, and no higher, lest the mixture be burnt too
much. Take the iron out, and immerse it in water to harden.” I consider
the vinegar to be quite superfluous.

I shall now describe the recent application of prussiate (ferrocyanate)
of potash to this purpose. The piece of iron, after being polished, is
to be made brightly red-hot, and then rubbed or sprinkled over with the
above salt in fine powder, upon the part intended to be hardened. The
prussiate being decomposed, and apparently dissipated, the iron is to
be quenched in cold water. If the process has been well managed, the
surface of the metal will have become so hard as to resist the file.
Others propose to smear over the surface of the iron with loam made into
a thin paste with a strong solution of the prussiate, to dry it slowly,
then expose the whole to a nearly white heat, and finally plunge the
iron into cold water, when the heat has fallen to dull redness. See
STEEL.


CASHMERE or CACHEMERE, a peculiar textile fabric first imported from the
kingdom of Cashmere, and now well imitated in France and Great Britain.
The material of the Cashmere shawls is the downy wool found about the
roots of the hair of the Thibet goat. The year 1819 is remarkable in the
history of French husbandry for the acquisition of this breed of goats,
imported from the East under the auspices of their government, by the
indefatigable courage and zeal of M. Jaubert, who encountered every
fatigue and danger to enrich his country with these valuable animals,
aided by the patriotism of M. Ternaux, who first planned this
importation, and furnished funds for executing it at his own expence and
responsibility. He placed a portion of the flock brought by M. Jaubert,
at his villa of Saint Ouen, near Paris, where the climate seemed to be
very favourable to them, since for several successive years after their
introduction M. Ternaux was enabled to sell a great number of both male
and female goats. The quantity of fine fleece or down afforded by each
animal annually, is from a pound and a half to two pounds.

The wool imported into Europe comes by the way of Casan, the capital of
a government of the Russian empire upon the eastern bank of the Wolga;
it has naturally a grayish colour, but is easily bleached. Its price a
few years back at Paris was 17 francs per kilogramme; that is, about 6
shillings the pound avoirdupois. The waste in picking, carding, and
spinning, amounts to about one third of its weight.

The mills for spinning Cachemere wool have multiplied very much of late
years in France, as appears from the premiums distributed at the
exposition of 1834, and the prices of the yarn have fallen from 25 to 30
per cent. notwithstanding their improved fineness and quality. There is
a fabric made with a mixture of Cachemere down and spun silk, which is
becoming very general. One of the manufacturers, M. Hindenlang,
exhibited samples of Cachemere cloth woven with yarn so fine as No. 130
for warp, and No. 228 for weft.

Messrs. Pollino, brothers, of Paris, produced an assortment of Cachemere
pieces from 22 to 100 francs the yard, dyed of every fancy shade. Their
establishment at Ferté-Bernard occupies 700 operatives, with an
hydraulic wheel of 60 horse power.

The oriental Cashmere shawls are woven by processes extremely slow and
consequently costly; whence their prices are very high. They are still
sold in Paris at from 4,000 to 10,000 francs a piece; and from 100 to
400 pounds sterling in London. It became necessary therefore either to
rest satisfied with work which should have merely a surface appearance,
or contrive economical methods of weaving, to produce the real Cachemere
style with much less labour. By the aid of the draw-loom and still
better of the Jacquard loom, M. Ternaux first succeeded in weaving
Cachemere shawls perfectly similar to the oriental in external aspect,
which became fashionable under the name of French Cachemere. But to
construct shawls altogether identical on both sides with the eastern,
was a more difficult task, which was accomplished only at a later period
by M. Bauson of Paris.

In both modes of manufacture, the piece is mounted by reading-in the
warp for the different leaves of the heddles, as is commonly practised
for warps in the Jacquard looms. The weaving of imitation shawls is
executed, as usual, by as many shuttles as there are colours in the
design, and which are thrown across the warp in the order established by
the _reader_. The greater number of these weft yarns being introduced
only at intervals into the web, when the composition of the pattern
requires it, they remain floating loose at the back of the piece, and
are cut afterwards, without affecting in the least the quality of the
texture; but there is a considerable waste of stuff in the weaving,
which is worked up into carpets.

The weaving of the imitation of real Cachemere shawls is different from
the above. The yarns intended to form the weft are not only equal in
number to that of the colours of the pattern to be imitated, but besides
this, as many little shuttles or pirns (like those used by embroiderers)
are filled with these yarns, as there are to be colours repeated in the
breadth of the piece; which renders their number considerable when the
pattern is somewhat complicated and loaded with colours. Each of these
small bobbins or shuttles passes through only that portion of the flower
in which the colour of its yarn is to appear, and stops at the one side
and the other of the cloth exactly at its limit; it then returns upon
itself after having crossed the thread of the adjoining shuttle. From
this reciprocal intertexture of all the yarns of the shuttles, it
results, that although the weft is composed of a great many different
threads, they no less constitute a continuous line in the whole breadth
of the web, upon which the lay or batten acts in the ordinary way We
see therefore that the whole art of manufacturing this Cachemere cloth
consists in avoiding the confusion of the shuttles, and in not striking
up the lay till all have fulfilled their function. The labour does not
exceed the strength of a woman, even though she has to direct the loom
and work the treddles. Seated on her bench at the end opposite to the
middle of the beam, she has for aids in weaving shawls from 45 to 52
inches wide, two girl apprentices, whom she directs and instructs in
their tasks. About four hundred days of work are required for a
Cachemere shawl of that breadth. For the construction of the loom, see
JACQUARD.

In the oriental process all the figures in relief are made simply with a
slender pirn without the shuttle used in European weaving. By the
Indians the flower and its ground are made with the pirn, by means of an
intertwisting, which renders them in some measure independent of the
warp. In the Lyons imitation of this style, the leaves of the heddles
lift the yarns of the warp, the needles embroider as in lappett weaving,
and the flower is united to the warp by the weft thrown across the
piece. Thus a great deal of labour is saved, the eye is pleased with an
illusion of the loom, and the shawls cost little more than those made by
the common fly shuttle.

Considered in reference to their materials, the French shawls present
three distinct classes, which characterise the three fabrics of Paris,
Lyons, and Nimes.

Paris manufactures the French Cachemere, properly so called, of which
both the warp and the weft are the yarn of pure Cachemere down. This web
represents with fidelity the figures and the shades of colour of the
Indian shawl, which it copies; the deception would be complete if the
reverse of the piece did not show the cut ends. The Hindoo shawl, also
woven at Paris, has its warp in spun silk, which reduces its price
without impairing its beauty much.

Lyons however has made the greatest progress in the manufacture of
shawls. It excels particularly in the texture of its Thibet shawls, the
weft of which is yarn spun with a mixture of wool and spun silk.

Nimes is remarkable for the low price of its shawls, in which spun silk,
Thibet down, and cotton, are all worked up together.

The value of shawls exported from France in the following years was:--

  +--------------+---------+---------+---------+
  |              |  1831.  |  1832.  |  1833.  |
  +--------------+---------+---------+---------+
  |              | Francs. | Francs. | Francs. |
  |Woollen       |1,863,147|2,070,926|4,319,601|
  |Cachemere down|  433,410|  655,200|  609,900|
  |Spun silk     |  401,856|  351,152|  408,824|
  +--------------+---------+---------+---------+

It appears that M. J. Girard at Sèvres, near Paris, has succeeded best
in producing Cachemere shawls equal in stuff and style of work to the
oriental, and at a lower price. They have this advantage over the Indian
shawls, that they are woven without seams, in a single piece, and
exhibit all the variety and the raised effect of the eastern colours.
Women and children alone are employed in his factory.


CASK, (_Tonneau_, Fr.; _Fass_, Germ.) manufacture of by mechanical
power. Mr. Samuel Brown obtained a patent in Nov., 1825, for certain
improvements in machinery for making casks, which seems to be ingenious
and worthy of record. His mechanism consists in the first place of a
circular saw attached to a bench, with a sliding rest, upon which rest
each piece of wood intended to form a stave of a cask is fixed; and the
rest being then slidden forward in a curved direction, by the assistance
of an adjustable guide, brings the piece of wood against the edge of the
rotatory saw, and causes it to be cut into the curved shape required for
the edge of the stave. The second feature is an apparatus with cutters
attached to a standard, and traversing round with their carrier upon a
centre, by means of which the upper and lower edges of the cask are cut
round and grooved, called chining, for the purpose of receiving the
heads. Thirdly, an apparatus not very dissimilar to the last, by which
the straight pieces of wood designed for the heads of the cask are held
together, and cut to the circular figure required, and also the bevelled
edges produced. And fourthly, a machine in which the cask is made to
revolve upon an axis, and a cutting tool to traverse for the purpose of
shaving the external part of the cask, and bringing it to a smooth
surface.

The pieces of wood intended to form the staves of the cask, having been
cut to their required length and breadth, are placed upon the slide-rest
of the first mentioned machine, and confined by cramps; and the guide,
which is a flexible bar, having been previously bent to the intended
curve of the stave and fixed in that form, the rest is then slidden
forward upon the bench by the hand of the workman, which as it advances
(moving in a curved direction) brings the piece of wood against the edge
of the revolving circular saw, by which it is cut to the curved shape
desired.

The guide is a long bar held by a series of movable blocks fitted to the
bench by screws, and is bent to any desired curve by shifting the
screws: the edge of the slide-rests which holds the piece of wood about
to be cut, runs against the long guide bar, and of consequence is
conducted in a corresponding curved course. The circular saw receives a
rapid rotatory motion by means of a band or rigger from any first mover;
and the piece of wood may be shifted laterally by means of racks and
pinions on the side-rest, by the workman turning a handle, which is
occasionally necessary in order to bring the piece of wood up to, or
away from, the saw.

The necessary number of staves being provided, they are then set round
within a confining hoop at bottom, and brought into the form of a cask
in the usual way, and braced by temporary hoops. The barrel part of the
cask being thus prepared, in order to effect the chining, it is placed
in a frame upon a platform, which is raised up by a treddle lever, that
the end of the barrel may meet the cutters in a sort of lathe above: the
cutters are then made to traverse round within the head of the barrel,
and, as they proceed, occasionally to expand, by which means the bevels
and grooves are cut on the upper edge of the barrel, which is called
chining. The barrel being now reversed, the same apparatus is brought to
act against the other end, which becomes chined in like manner.

The pieces of wood intended to form the heads of the cask are now to be
cut straight by a circular saw in a machine, similar to the first
described; but in the present instance the slide-rest is to move forward
in a straight course. After their straight edges are thus produced, they
are to be placed side by side, and confined, when a scribing cutter is
made to traverse round, and cut the pieces collectively into the
circular form desired for heading the cask.

The cask having now been made up, and headed by hand as usual, it is
placed between centres, or upon an axle in a machine, and turned round
by a rigger or band with a shaving cutter, sliding along a bar above it,
which cutter being made to advance, and recede as it slides along,
shaves the outer part of the cask to a smooth surface.


CASSAVA. _Cassava bread_, _conaque_, _&c._, are different names given to
the starch of the root of the Manioc (_Jatropha Manihot_, Linn.),
prepared in the following manner in the West Indies, the tropical
regions of America, and upon the African coast. The tree belongs to the
natural family of the _euphorbiaceæ_.

The roots are washed, and reduced to a pulp by means of a rasp or
grater. The pulp is put into coarse strong canvas bags, and thus
submitted to the action of a powerful press, by which it parts with most
of its noxious juice (used by the Indians for poisoning the barbs of
their arrows). As the active principle of this juice is volatile, it is
easily dissipated by baking the squeezed cakes of pulp upon a plate of
hot iron. Fifty pounds of the fresh juice, when distilled, afford, at
first, three ounces of a poisonous water, possessing an intolerably
offensive smell; of which, 35 drops being administered to a slave
convicted of the crime of poisoning, caused his death in the course of
six minutes, amid horrible convulsions.[16]

  [16] Memoir of Dr. Fermin, communicated to the Academy of Berlin,
  concerning experiments made at Cayenne, upon the juice of the Manioc.

The pulp dried in the manner above described concretes into lumps, which
become hard and friable as they cool. They are then broken into pieces,
and laid out in the sun to dry. In this state they afford a wholesome
nutriment, and are habitually used as such by the negroes, as also by
many white people. These cakes constitute the only provisions laid in by
the natives, in their voyages upon the Amazons. Boiled in water with a
little beef or mutton they form a kind of soup similar to that of rice.

The Cassava cakes sent to Europe (which I have eaten with pleasure) are
composed almost entirely of starch, along with a few fibres of the
ligneous matter. It may be purified by diffusion through warm water,
passing the milky mixture through a linen cloth, evaporating the
strained liquid over the fire, with constant agitation. The starch
dissolved by the heat, thickens as the water evaporates, but on being
stirred, it becomes granulated, and must be finally dried in a proper
stove. Its specific gravity is 1·530--that of the other species of
starch.

The product obtained by this treatment is known in commerce under the
name of _tapioca_; and being starch very nearly pure, is often
prescribed by physicians as an aliment of easy digestion. A tolerably
good imitation of it is made by heating, stirring, and drying potato
starch in a similar way.

The expressed juice of the root of manioc contains in suspension a very
fine fecula, which it deposits slowly upon the bottom of the vessels.
When freed by decantation from the supernatant liquor, washed several
times and dried, it forms a beautiful starch, which creaks on pressure
with the fingers. It is called _cipipa_, in French Guyana; it is
employed for many delicate articles of cookery, especially pastry, as
also for hair powder, starching linen, &c.

Cassava flour, as imported, may be distinguished from arrow-root and
other kinds of starch, by the appearance of its particles viewed in a
microscope. They are spherical, all about 1-1000th of an inch in
diameter, and associated in groups; those of potato starch are irregular
ellipsoids, varying in size from 1-300th to 1-3000th of an inch; those
of arrow-root have the same shape nearly, but vary in size from 1-500th
to 1-800th of an inch; those of wheat are separate spheres 1-1000th of
an inch.


CASSIS, the black currant (_ribes nigra_, Linn.), which was formerly
celebrated for its medicinal properties with very little reason.

The only technical use to which it is now applied is in preparing the
agreeable _liqueur_ called _ratafia_, by the following French
recipe:--Stone, and crush three pounds of black currants, adding to the
magma one drachm of cloves, two of cinnamon, four quarts of spirit of
wine, at 18° Baumé (see ARÉOMÈTRE OF BAUMÉ), and 2-1/2 pounds of sugar.
Put the mixture into a bottle which is to be well corked; let it digest
for a fortnight, shaking the bottle once daily during the first eight
days; then strain through a linen cloth, and finally pass through
filtering paper.


CASTING OF METALS. (See FOUNDING.) _Casts from elastic moulds._--Being
much engaged in taking casts from anatomical preparations, Mr. Douglas
Fox, Surgeon, Derby, found great difficulty, principally with hard
bodies, which, when undercut, or having considerable overlaps, did not
admit of the removal of moulds of the ordinary kind, except with injury.
These difficulties suggested to him the use of elastic moulds, which,
giving way as they were withdrawn from complicated parts, would return
to their proper shape; and he ultimately succeeded in making such moulds
of glue, which not only relieved him from all his difficulties, but were
attended with great advantages, in consequence of the small number of
pieces into which it was necessary to divide the mould.

The body to be moulded, previously oiled, must be secured one inch above
the surface of a board, and then surrounded by a wall of clay, about an
inch distant from its sides. The clay must also extend rather higher
than the contained body: into this, warm melted glue, as thick as
possible so that it will run, is to be poured, so as to completely cover
the body to be moulded; the glue is to remain till cold, when it will
have set into an elastic mass, just such as is required.

Having removed the clay, the glue is to be cut into as many pieces as
may be necessary for its removal, either by a sharp-pointed knife, or by
having placed threads in the requisite situations of the body to be
moulded, which may be drawn away when the glue is set, so as to cut it
out in any direction.

The portions of the glue mould having been removed from the original,
are to be placed together and bound round by tape.

In some instances it is well to run small wooden pegs through the
portions of glue, so as to keep them exactly in their proper positions.
If the mould be of considerable size, it is better to let it be bound
with moderate tightness upon a board to prevent it bending whilst in
use; having done as above described, the plaster of Paris, as in common
casting, is to be poured into the mould, and left to set.

In many instances wax may also be cast in glue, if it is not poured in
whilst too hot; as the wax cools so rapidly when applied to the cold
glue, that the sharpness of the impression is not injured.

Glue has been described as succeeding well where an elastic mould is
alone applicable; but many modifications are admissible. When the moulds
are not used soon after being made, treacle should be previously mixed
with the glue (as employed by printers) to prevent it becoming hard.

The description thus given is with reference to moulding those bodies
which cannot be so done by any other than an elastic mould; but glue
moulds will be found greatly to facilitate casting in many departments,
as a mould may be frequently taken by this method in two or three
pieces, which would, on any other principle, require many.


CASTOR. (Eng. and Fr.; _Biber_, Germ.) The castor is an amphibious
quadruped, inhabiting North America; also found in small numbers in the
islands of the Rhone. In the arts, the skin of this animal is employed
either as a fur or as affording the silky hair called beaver, with which
the best hats are covered. Beaver skins, which form a very considerable
article of trade, are divided into 3 sorts: 1. The fresh beaver skins
from castors, killed in winter before shedding their hair; these are
most in request among the furriers, as being the most beautiful. 2. The
dry or lean beavers are the skins of the animals killed during the
moulting season; they are not much esteemed, as the skin is rather bare.
3. The fat castors: these are the skins of the first sort, which have
been worn for some time upon the persons of the savages and have got
imbued with their sweat. The last are principally used in the hat
manufacture. In France, the marine otter has been for many years
substituted in the place of the castor or beaver.


CASTOR or CASTOREUM. This name is given to a secretion of the castors,
contained in pear-shaped cellular organic sacs, placed near the genital
organs of both the male and female animals. It is a substance analogous
to civet and musk, of a consistence similar to thick honey. It has a
bitter acrid taste; a powerful, penetrating, fetid, and very volatile
smell; but, when dried, it becomes inodorous. Several chemists, and in
particular Bouillon Lagrange, Laugier, and Hildebrandt have examined
castor; and found it to be composed of a resin, a fatty substance, a
volatile oil, an extractive matter, benzoic acid, and some salts.

The mode of preparing it is very simple. The sacs are cut off from the
castors when they are killed, and are dried to prevent the skin being
affected by the weather. In this state, the interior substance is solid,
of a dark colour, and a faint smell; it softens with heat, and becomes
brittle by cold. Its fracture betrays fragments of membranes, indicating
its organic structure. When chewed, it adheres to the teeth somewhat
like wax; it has a bitter, slightly acrid, and nauseous taste.

The castor bags, as imported, are often joined in pairs by a kind of
ligature. Sometimes the substance which constitutes their value is
sophisticated; a portion of the castoreum being extracted, and replaced
by lead, clay, gums, or some other foreign matters. This fraud may be
easily detected, even when it exists in a small degree, by the absence
of the membranous partitions in the interior of the bags, as well as by
the altered smell and taste.

The use of castoreum in medicine is considerable, especially in nervous
and spasmodic diseases, and it is often advantageously combined with
opium.


CASTORINE. A chemical principle lately discovered to the amount of a few
parts per cent. in Castoreum.


CASTOR OIL. The expressed oil of the seeds of the _Palma Christi_, or
_Ricinus communis_, a native tree of the West Indies and South America;
but which has been cultivated in France, Italy, and Spain. Bussy and
Lecanu discovered in it 3 species of fatty matters, obtained partly by
saponification, and partly by dry distillation--the margaritic, ricinic,
and elaiodic acids. None of these has been separately applied to any use
in the arts.

The quantity of castor oil imported in 1835 into the United Kingdom, was
1,109,307 libs.; retained for home consumption, 670,205 libs. See OILS.


CATECHU, absurdly called Terra Japonica, is an extract made from the
wood of the tree _mimosa catechu_, which grows in Bombay, Bengal, and
other parts of India. It is prepared by boiling the chips of the
interior of the trunk in water, evaporating the solution to the
consistence of syrup over the fire, and then exposing it in the sun to
harden. It occurs in flat rough cakes, and under two forms. The first,
or the Bombay, is of uniform texture, of a dark red colour, and of
specific gravity 1·39. The second is more friable and less solid. It has
a chocolate colour, and is marked inside with red streaks. Its specific
gravity is 1·28.

According to Sir H. Davy, these two species are composed as follows:--

  +--------------------------------+-------+-------+
  |                                |Bombay.|Bengal.|
  +--------------------------------+-------+-------+
  |Tannin                          |  54·5 |  48·5 |
  |Extractive                      |  34·0 |  36·5 |
  |Mucilage                        |   6·5 |   8   |
  |Insoluble matters, sand and lime|   5   |   7   |
  |                                +-------+-------+
  |                                | 100·0 | 100·0 |
  +--------------------------------+-------+-------+

Areka nuts are also found to yield catechu; for which purpose they are
cut into pieces watered in an earthen pot with solution of nitre, and
have a little of the bark of a species of mimosa added to them. The
liquor is then boiled with the nuts, and affords an inspissated
decoction.

Good catechu is a brittle, compact solid, of a dull fracture. It has no
smell, but a very astringent taste. Water dissolves the whole of it,
except the earthy matter, which is probably added during its
preparation. Alcohol dissolves its tannin and extractive. The latter may
be oxidized, and thus rendered insoluble in alcohol, by dissolving the
catechu in water, exposing it for some time to a boiling heat, and
evaporating to dryness.

The tannin of catechu differs from that of galls, in being soluble in
alcohol, and more soluble in water. It precipitates iron of an olive
colour, and gelatine in a mass which gradually becomes brown.

It has been long employed in India for tanning skins, where it is said
to effect this object in five days. I have seen a piece of sole leather
completely tanned by it in this country in ten days, the ox-hide having
been made into a bag, with the hair outside, and kept filled with the
solution of catechu. In India it has also been used to give a brown dye
to cotton goods, and of late years it has been extensively introduced
into the calico print-works of Europe. The salts of copper with sal
ammoniac cause it to give a bronze colour, which is very fast; the
proto-muriate of tin, a brownish yellow; the per-chloride of tin, with
the addition of nitrate of copper, a deep bronze hue; acetate of alumina
alone, a reddish brown, and, with nitrate of copper, a reddish olive
gray; nitrate of iron, a dark brown gray. For dyeing a golden coffee
brown, it has entirely superseded madder; one pound of it being
equivalent to six pounds of this root.

A solution of one part of catechu in ten parts of water, which is
reddish brown, exhibits the following results with--

  Acids                     A brightened shade.
  Alkalis                   A darkened shade.
  Proto-sulphate of iron    Olive brown precipitate.
  Per-sulphate of iron      Olive green    do.
  Sulphate of copper        Yellowish brown.
  Alum                      A brightening of the liquor.
  Per-nitrate of iron       Olive green precipitate.
  Nitrate of copper         Yellowish brown do.
  Nitrate of lead           Salmon          do.
  Proto-nitrate of mercury  Milk-coffee     do.
  Muriate of alumina        Brown yellow.
  Muriate of tin             Do.    do.
  Per-chloride of tin        Do.  darker.
  Corrosive sublimate       Light chocolate do.
  Acetate of alumina        Brightening of the liquor.
  Acetate of copper         Copious brown precipitate.
  Acetate of lead           Salmon coloured   do.
  Bichromate of potash      Copious brown     do.

Pure tannin may be obtained from catechu, by treating it with sulphuric
acid and carbonate of lead; but this process has no manufacturing
application.


CATGUT, (_Corde à boyau_, Fr.; _Darmsaite_, Germ.) the name absurdly
enough given to cords made of the twisted intestines of the sheep. The
guts being taken while warm out of the body of the animal, are to be
cleared of feculent matter, freed from any adhering fat, and washed in a
tub of water. The small ends of all the intestines are next to be tied
together, and laid on the edge of the tub, while the body of them is
left to steep in some water, frequently changed, during two days, in
order to loosen the peritoneal and mucous membranes. The bundle of
intestines is then laid upon a sloping table which overhangs the tub,
and their surface is scraped with the back of a knife, to try if the
external membrane will come away freely in breadths of about half the
circumference. This substance is called by the French manufacturers
_filandre_, and the process _filer_. If we attempt to remove it by
beginning at the large end of the intestine, we shall not succeed. This
_filandre_ is employed as thread to sew intestines, and to make the
cords of rackets and battledores. The flayed guts are put again into
fresh water, and after steeping a night, are taken out and scraped clean
next day, on the wooden bench with the rounded back of a knife. This is
called _curing the gut_. The large ends are now cut off, and sold to the
pork-butchers. The intestines are again steeped for a night in fresh
water, and the following day in an alkaline lixivium made by adding 4
ounces of potash, and as much pearlash, to a pail of water containing
about 3 or 4 imperial gallons. This lye is poured in successive
quantities upon the intestines, and poured off again, after 2 or 3
hours, till they be purified. They are now drawn several times through
an open brass thimble, and pressed against it with the nail, in order to
smooth and equalize their surface. They are lastly sorted, according to
their sizes, to suit different purposes.

_Whip-cord_ is made from the above intestines, which are sewed together
endwise by the _filandre_, each junction being cut aslant, so as to make
it strong and smooth. The cord is put into the frame, and each end is
twisted separately; for whip-cord is seldom made out of two guts twisted
together. When twisted it is to be sulphured (see SULPHURING) once or
twice. It may also be dyed black with common ink, pink with red ink,
which the sulphurous acid changes to pink, and green with a green dye
which the colour dealers sell for the purpose. The guts take the dyes
readily. After being well smoothed, the cord is to be dried, and coiled
up for sale.

_Hatter’s cords for bowstrings._--The longest and largest intestines of
sheep, after being properly treated with the potash, are to be twisted
4, 6, 8, 10, or 12 together, according to the intended size of the cord,
which is usually made from 15 to 25 feet long. This cord must be free
from seams and knots. When half dry, it must be exposed twice to the
fumes of burning sulphur; and, after each operation, it is to be well
stretched and smoothed; it should be finally dried in a state of
tension.

_Clockmaker’s cord._--This cord should be extremely thin, and be
therefore made from very small intestines, or from intestines slit up
in their length by a knife fitted for the purpose; being a kind of
lancet surmounted with a ball of lead or wood. The wet gut is strained
over the ball which guides the knife, and the two sections fall down
into a vessel placed beneath. Each hand pulls a section. Clockmakers
also make use of stronger cords made of 2 or more guts twisted together.

_Fiddle and harp strings._--These require the greatest care and
dexterity on the part of the workmen. The treble strings are peculiarly
difficult to make, and are best made at Naples, probably because their
sheep, from their small size and leanness, afford the best raw material.

The first scraping of the guts intended for fiddle-strings must be very
carefully performed; and the alkaline lyes being clarified with a little
alum, are added, in a progressively stronger state from day to day,
during 4 or 5 days, till the guts be well bleached and swollen. They
must then be passed through the thimble, and again cleansed with the
lixivium; after which they are washed, spun, or twisted and sulphured
during two hours. They are finally polished by friction, and dried.
Sometimes they are sulphured twice or thrice before being dried, and are
polished between horse-hair cords.

It has been long a subject of complaint, as well as a serious
inconvenience to musicians, that catgut strings cannot be made in
England of the same goodness and strength as those imported from Italy.
These are made of the peritoneal covering of the intestines of the
sheep; and, in this country, they are manufactured at Whitechapel, and
probably elsewhere in considerable quantity; the consumption of them for
harps, as well as for the instruments of the violin family, being very
great. Their chief fault is weakness; whence it is difficult to bring
the smaller ones, required for the higher notes, to concert pitch;
maintaining at the same time, in their form and construction, that
tenuity or smallness of diameter, which is required to produce a
brilliant and clear tone.

The inconvenience arising from their breaking when in use, and the
expense in the case of harps, where so many are required, are such as to
render it highly desirable to improve a manufacture which, to many
individuals may, however, appear sufficiently contemptible.

It is well known to physiologists, that the membranes of lean animals
are far more tough than of those animals which are fat or in high
condition; and there is no reason to doubt that the superiority of the
Italian strings arises from the state of the sheep in that country. In
London, where no lean animals are slaughtered, and where, indeed, an
extravagant and useless degree of fattening, at least for the purpose of
food, is given to sheep in particular, it is easy to comprehend why
their membranes can never afford a material of the requisite tenacity.
It is less easy to suggest an adequate remedy; but a knowledge of the
general principle, should this notice meet the eyes of those interested
in the subject, may at least serve the purpose of diminishing the evil
and improving the manufacture, by inducing them to choose in the market
the offal of such carcases as appear least overburthened with fat. It is
probable that such a manufacture might be advantageously established in
those parts of the country where the fashion has not, as in London, led
to the use of meat so much overfed; and it is equally likely, that in
the choice of sheep for this purpose, advantage would arise from using
the Welch, the Highland, or the Southdown breeds, in preference to those
which, like the Lincoln, are prone to excessive accumulations of fat. It
is equally probable, that sheep dying of some of the diseases
accompanied by emaciation, would be peculiarly adapted to this purpose.

That these suggestions are not merely speculative is proved by comparing
the strength of the membranes in question, or that of the other
membranous parts, in the unfattened Highland sheep, with that of those
found in the London markets.


CATHARTINE. The name proposed by MM. Feneulle and Lassaigne for a
chemical principle, which they suppose to be the active constituent of
senna.


CAUSTIC. Any chemical substance corrosive of the skin and flesh; as
potash, called common caustic, and nitrate of silver, called lunar
caustic, by surgeons.


CAVIAR. The salted roe of certain species of fish, especially the
sturgeon. This product forms a considerable article of trade, being
exported annually from the town of Astrachan alone, upon the shores of
the Caspian sea, to the amount of several hundred tons. The Italians
first introduced it into Eastern Europe from Constantinople, under the
name of _caviale_. Russia has now monopolized this branch of commerce.
It is prepared in the following manner:--

The female sturgeon is gutted; the roe is separated from the other
parts, and cleaned by passing it through a very fine searce, by rubbing
it into a pulp between the hands: this is afterwards thrown into tubs,
with the addition of a considerable quantity of salt; the whole is then
well stirred, and set aside in a warm apartment. There is another sort
of caviar, the compressed, in which the roe, after having been cured in
strong brine, is dried in the sun, then put into a cask, and subjected
to strong pressure.


CAWK. The English miner’s name for sulphate of baryta, or heavy spar.


CEDRA, (_Cedrat_, Fr.) is the fruit of a species of orange, citron, or
lemon, a tree which bears the same name. Its peel is very thick, and
covered with an epidermis which encloses a very fragrant and highly
prized essential oil. The preserves flavoured with it are very
agreeable. The citrons are cut into quarters for the dry comfits, but
are put whole into the liquid ones. The liquorist-perfumer makes with
the peel of the _cedra_ an excellent _liqueur_; for which purpose, he
plucks them before they are quite ripe; grates down the peel into a
little brandy, or cuts them into slices, and infuses these in the
spirits. This infusion is distilled for making perfume; but the flavour
is better when the infusion itself is used. See ESSENCES, LIQUORIST,
PERFUMERY.


CELESTINE. Native sulphate of strontia, found abundantly near Bristol,
in the red marl formation. It is decomposed, by ignition with charcoal,
into sulphuret of strontia, which is converted into nitrate by
saturation with nitric acid, evaporation, and crystallization. This
nitrate is employed for the production of the red light in theatrical
fire-works.


CEMENTATION. A chemical process, which consists in imbedding a solid
body, in a pulverulent matter, and exposing both to ignition in an
earthen or metallic case. In this way, iron is cemented with charcoal to
form steel, and bottle glass with gypsum powder, or sand, to form
Reaumur’s porcelain.


CEMENTS. (_Ciments_, Fr.; _Cämente_, _Kitte_, Germ.) Substances capable
of taking the liquid form, and of being in that state applied between
the surfaces of two bodies, so as to unite them by solidifying. They may
be divided into two classes, those which are applied through the agency
of a liquid menstruum, such as water, alcohol, or oil, and those which
are applied by fusion with heat.

The _diamond_ cement for uniting broken pieces of china, glass, &c.
which is sold as a secret at an absurdly dear price, is composed of
isinglass soaked in water till it becomes soft, and then dissolved in
proof spirit, to which a little gum resin, ammoniac, or galbanum, and
resin mastic are added, each previously dissolved in a minimum of
alcohol. When to be applied, it must be gently heated to liquefy it; and
it should be kept for use in a well-corked phial. A glass stopper would
be apt to fix so as not to be removable. This is the cement employed by
the Armenian jewellers in Turkey for glueing the ornamental stones to
trinkets of various kinds. When well made it resists moisture.

Shell-lac dissolved in alcohol, or in a solution of borax, forms a
pretty good cement. White of egg alone, or mixed with finely sifted
quick lime, will answer for uniting objects which are not exposed to
moisture. The latter combination is very strong, and is much employed
for joining pieces of spar and marble ornaments. A similar composition
is used by copper-smiths to secure the edges and rivets of boilers; only
bullock’s blood is the albuminous matter used instead of white of egg.
Another cement in which an analogous substance, the curd or caseum of
milk is employed, is made by boiling slices of skim-milk cheeses into a
gluey consistence in a great quantity of water, and then incorporating
it with quicklime on a slab with a muller, or in a marble mortar. When
this compound is applied warm to broken edges of stoneware, it unites
them very firmly after it is cold.

A cement which gradually indurates to a stony consistence may be made by
mixing 20 parts of clean river sand, two of litharge, and one of
quicklime, into a thin putty with linseed oil. The quicklime may be
replaced with litharge. When this cement is applied to mend broken
pieces of stone, as steps of stairs, it acquires after some time a stony
hardness. A similar composition has been applied to coat over brick
walls, under the name of mastic.

The iron-rust cement is made of from 50 to 100 parts of iron borings,
pounded and sifted, mixed with one part of sal-ammoniac, and when it is
to be applied moistened with as much water as will give it a pasty
consistency. Formerly flowers of sulphur were used, and much more
sal-ammoniac in making this cement, but with decided disadvantage, as
the union is effected by the oxidizement, consequent expansion and
solidification of the iron powder, and any heterogeneous matter
obstructs the effect. The best proportion of sal-ammoniac is, I believe,
one per cent. of the iron borings. Another composition of the same kind
is made by mixing 4 parts of fine borings or filings of iron, 2 parts of
potter’s clay, and 1 part of pounded potsherds, and making them into a
paste with salt and water. When this cement is allowed to concrete
slowly on iron joints, it becomes very hard.

For making architectural ornaments in relief, a moulding composition is
formed of chalk, glue, and paper paste. Even statues have been made with
it, the paper aiding the cohesion of the mass.

Mastics of a resinous or bituminous nature which must be softened or
fused by heat are the following:--

Mr. S. Varley’s consists of sixteen parts of whiting sifted and
thoroughly dried by a red heat, adding when cold a melted mixture of 16
parts of black rosin and 1 of bees’-wax, and stirring well during the
cooling.

Mr. Singer’s electrical and chemical apparatus cement consists of 5 lbs.
of rosin, 1 of bees’-wax, 1 of red ochre, and two table-spoonsful of
Paris-plaster, all melted together. A cheaper one for cementing voltaic
plates into wooden troughs is made with 6 pounds of rosin, 1 pound of
red ochre, 1/2 of a pound of plaster of Paris, and 1/4 of a pound of
linseed oil. The ochre and the plaster of Paris should be calcined
beforehand, and added to the other ingredients in their melted state.
The thinner the stratum of cement that is interposed, the stronger
generally speaking is the junction.

Boiled linseed oil and red lead mixed together into a putty are often
used by coppersmiths and engineers, to secure joints. The washers of
leather or cloth are smeared with this mixture in a pasty state.

The resin mastic alone is sometimes used by jewellers to cement by heat
cameos of white enamel or coloured glass to a real stone, as a ground to
produce the appearance of an onyx. Mastic is likewise used to cement
false backs or doublets to stones to alter their hue.

Melted brimstone either alone, or mixed with rosin and brick dust, forms
a tolerably good and very cheap cement.

Plumber’s cement consists of black rosin one part, brick dust two parts,
well incorporated by a melting heat.

The cement of dihl for coating the fronts of buildings consists of
linseed oil, rendered dry by boiling with litharge, and mixed with
porcelain clay in fine powder, to give it the consistence of stiff
mortar. Pipe-clay would answer equally well if well dried, and any
colour might be given with ground bricks, or pottery. A little oil of
turpentine to thin this cement aids its cohesion upon stone, brick, or
wood. It has been applied to sheets of wire cloth, and in this state
laid upon terraces, in order to make them water tight; but it is little
less expensive than lead.

The bituminous or black cement for bottle corks consists of pitch
hardened by the addition of rosin and brick-dust.

In certain localities where a limestone impregnated with bitumen occurs,
it is dried, ground, sifted, and then mixed with about its own weight of
melted pitch, either mineral, vegetable, or that of coal tar. When this
mixture is getting semifluid, it may be moulded into large slabs or
tiles in wooden frames lined with sheet iron, previously smeared over
with common lime mortar, in order to prevent adhesion to the moulds,
which, being in movable pieces, are easily dismounted so as to turn out
the cake of artificial bituminous stone. This cement is manufactured
upon a great scale in many places, and used for making Italian terraces,
covering the floors of balconies, flat roofs, water reservoirs, water
conduits, &c. When laid down, the joints must be well run together with
hot irons. The floor of the terrace should be previously covered with a
layer of Paris plaster or common mortar, nearly an inch thick, with a
regular slope of one inch to the yard. Such bituminous cement weighs 144
pounds the cubic foot; or a foot of square surface, one inch thick,
weighs 12 pounds. Sometimes a second layer of these slabs or tiles is
applied over the first, with the precaution of making the seams or
joints of the upper correspond with the middle of the under ones.
Occasionally a bottom bed, of coarse cloth or gray paper, is applied.
The larger the slabs are made, as far as they can be conveniently
transported and laid down, so much the better. For _hydraulic_ cements,
see MORTAR.


CERASIN. The name given by Dr. John to those gums which swell, but do
not dissolve in water; such as gum tragacanth. It is synonymous with
BASSORINE, which see.


CERATE from _cera_, _wax_. An unguent, of rather a stiff consistence,
made of oil, or lard and wax, thickened occasionally with pulverulent
matters.


CERINE. A substance which forms from 70 to 80 per cent. of bees’-wax. It
may be obtained by digesting wax, for some time, in spirit of wine, at a
boiling temperature. The _myricine_ separates, while the _cerine_
remains dissolved, and may be obtained from the decanted liquor by
evaporation. Cerine is white, analogous to wax, fusible at 134° F.,
hardly acted upon by hot nitric acid, but is readily carbonized by hot
sulphuric acid. When treated with caustic alkaline lye, it is converted
into margaric acid and _ceraïne_.


CERIUM. A peculiar metal discovered in the rare mineral, called
_cerite_, found only in the copper mine of Bastnaes, near Riddarhytta,
in Sweden. Cerium, extracted from its chloride by potassium, appears as
a dark red or chocolate powder, which assumes a metallic lustre by
friction. It does not conduct electricity well, like other metals; it is
infusible; its specific gravity is unknown. It has been applied to no
use in the arts.


CERUSE. A name of white lead. See LEAD.


CETINE. The name given by Chevreul to spermaceti.


CHAINWORK is a peculiar style of textile fabric, to which hosiery and
tambouring belong. See HOSIERY.


CHALK. (_Craie_, Fr.; _Kreide_, Germ.) A friable carbonate of lime,
white, opaque, soft, dull, or without any appearance of polish in its
fracture. Its specific gravity varies from 2·4 to 2·6. It usually
contains a little silica, alumina, and oxide of iron. It may be purified
by trituration, and elutriation. The siliceous and ferruginous matters
subside first, and the finer chalky particles floating in the
supernatant liquid, may be decanted with it, and obtained by subsidence.
When thus purified, it is called _whitening_ and Spanish white, in
England; _schlemmkreide_, in Germany; _blanc de Troyes_, and _blanc de
Meudon_, in France. Pure chalk should dissolve readily in dilute
muriatic acid, and the solution should afford no precipitate with water
of ammonia.


CHALK--_Black_. A mineral, called also _drawing-slate_.


CHALK--_French_. _Steatite_, or soap stone; a soft magnesian mineral.


CHALK--_Red_. A clay coloured with the peroxide of iron, of which it
contains about 17 per cent.


CHARCOAL. The fixed residuum of vegetables exposed to ignition out of
contact of air. In the article CARBON, I have described the general
properties of charcoal and the simplest mode of making it. I shall here
detail the best systems of manufacturing this product upon the continent
of Europe.

[Illustration: 272 273 274]

To carbonize wood under a movable covering, the plan of _meiler_, or
heaps, is employed very much in Germany. The wood is arranged either in
horizontal layers, or in nearly vertical ones, with a slight slope, so
as to form conical rounded heaps of different sizes. The former are
called lying _meiler_, _fig._ 272.; the latter standing _meiler_,
_figs._ 273. and 274. Both are distributed in much the same way.

[Illustration: 275]

In districts where the wood can be transported into one place by means
of rivers, or mountain slides, a dry flat space must be pitched upon,
screened from storms and floods, which may be walled round, having a
slight declivity made in the ground, towards the centre. See _fig._ 275.
Into this space the tarry acid will partially fall, and may be conducted
outwards, through a covered gutter beneath, into a covered tank. The
mouth of the tank must be shut, during the coaking, with an iron or
stone slab, luted with clay. A square iron plate is placed over the
inner orifice of the gutter, to prevent it being choked with coal ashes.
_Fig._ 275. represents a walled _meiler_ station; _a_, the station; _b_,
the gutter; _c_, the tank, which is covered with the slab _d_; _e_, a
slab which serves to keep the gutter clear of coals. The cover of the
heaps is formed of earth, sand, ashes, or such other matter as may be
most readily found in the woods. They should be kindled in the centre.
From 6 days to 4 weeks may be required for charring a heap, according to
its size; hard wood requiring most time; and the slower the process, the
better and greater is the product, generally speaking.

[Illustration: 276 277]

Charring of wood in mounds (_Haufe_ or _liegende werke_) _figs._ 276.
and 277. differs from that in the _meiler_, because the wood in the
_haufe_ is successively charred, and the charcoal is raked out by little
and little. The product is said to be greater in this way, and also
better. Uncleft billets, 6 or 8 feet long, being laid over each other,
are covered with ashes, and then carbonized. The station is sometimes
horizontal, and sometimes made to slope. The length may be 24 feet, the
breadth 8 feet; and the wood is laid crosswise. Piles are set
perpendicularly to support the roof, made of boughs and leaves, covered
with ashes. Pipes are occasionally laid within the upper part of the
mounds, which serve to catch and carry off some of the liquid products
into proper tanks.

[Illustration: 278 279]

_Fig._ 278. is a vertical section, and _fig._ 279. a half bird’s-eye
view, and half cross section, at the height of the pit-bottom, of
Chabeaussière’s kiln for making wood charcoal. _a_ is the oven; _b_,
vertical air-pipes; _c c_, horizontal flues for admitting air to the
kiln; _d d_, small pits which communicate by short horizontal pipes _e
e_, with the vertical ones; _f_, the sole of the kiln, a circle of
brickwork, upon which the cover or hood _h_ reposes; _i_, a pipe which
leads to the cistern _k_; _l_, the pipe destined for carrying off the
gaseous matter; _m m_, holes in the iron cover or lid.

The distribution of the wood is like that in the horizontal _meilers_,
or heaps; it is kindled in the central vertical canal with burning fuel,
and the lid is covered with a few inches of earth. At the beginning of
the operation all the draught flues are left open, but they are
progressively closed, as occasion requires. In eight kilns of this kind,
500 _decasters_ of oak wood are carbonized, from which 16,000
hectolitres of charcoal are obtained, equal to 64,000 pounds French,
being about 25 per cent.; besides tar and 3000 velts of wood vinegar, of
from 2° to 3°. _Baumé_.

[Illustration: 280]

At Crouy upon the Ourcq, near Meaux, there is a well constructed kiln
for making turf-charcoal. It resembles most nearly a tar-kiln. In _fig._
280. _a_ is the cylindrical coaking place, whose surrounding walls are
heated by the flame which passes through the intermediate space _b_. The
place itself is divided by partitions of fire tiles into three stages,
through the apertures in which the flames of the fire _c c_, rise, and
heat the exterior of the coaking apartment. In order to confine the
heat, there is in the enclosing walls of the outer kiln a cylindrical
hollow space _d_, where the air is kept stagnant. Through the apertures
left in the upper end at _e_, the turf is introduced; they are then shut
with an iron plate _f_, which is covered with ashes or sand. The
fire-place opens above this aperture, and its outlet is provided with a
moveable iron cover _g_, in which there is a small hole for the issue of
the gases. The sole of the kiln consists of a cast iron slab _h_, which
may be raised by means of a hook _i_ upon it. This is drawn back after
the carbonization is completed, whereby the charcoal falls from the
coaking space into a subjacent vault. The volatile products are carried
off by the pipe _k_, and led into the condensing cistern; the gases
escaping to the fire-place where they are burned. The iron slab is
protected from the corrosion of the acid vapours by a layer of coal
ashes.


CHICA is a red colouring principle made use of in America by some Indian
tribes to stain their skins. It is extracted from the _bignonia chica_
by boiling its leaves in water, decanting the decoction, and allowing it
to settle and cool, when a red matter falls down, which is formed into
cakes and dried. This substance is not fusible, and, when burned,
diffuses the same odour as animal bodies do. It is insoluble in cold
water, very soluble in alcohol and ether, but, after the evaporation of
these liquids, it is recovered unchanged. Fats and unctuous oils both
dissolve it. It is soluble in carbonated and caustic alkaline lyes, from
which it is precipitated by the acids without alteration. An excess of
alkali, however, speedily decomposes it. Nitric acid transforms it into
oxalic acid, and a bitter matter. Chlorine makes it white.

The savages mix this pigment with the fat of the cayman or alligator,
and rub their skins with the mixture. It may probably be turned to
account in the arts of civilized nations.


CHIMNEY. (_Cheminée_, Fr.; _Schornstein_, Germ.) Chimney is a modern
invention for promoting the draught of fires and carrying off the smoke,
introduced into England so late as the age of Elizabeth, though it seems
to have been employed in Italy 100 years before. The Romans, with all
their luxurious refinements, must have had their epicurean cookery
placed in perpetual jeopardy from their kitchen fires, which, having no
vent by a vertical tunnel in the walls, discharged their smoke and
frequently their flames at the windows, to the no small alarm of their
neighbours, and annoyance of even the street passengers.

Chimneys in dwelling houses serve also the valuable purpose of promoting
salubrious circulation of air in the apartments, when not foolishly
sealed with anti-ventilating stove-chests.

The first person who sought to investigate the general principles of
chimney draughts, in subserviency to manufacturing establishments, was
the celebrated Montgolfier. As the ascent of heated air in a conduit
depends upon the diminution of its specific gravity, or, in other words,
upon the increase of its volume by the heat, the ascensional force may
be deduced from the difference between the density of the elastic fluid
in the interior of the chimney, and of the external air; that is,
between the different heights of the internal and external columns of
elastic fluid supposed to be reduced to the same density. In the latter
case, the velocity of the gaseous products of combustion in the interior
of the chimney is equal to that of a heavy body let fall from a height
equal to the difference in height of the two aerial columns.

To illustrate this position by an example, let us consider the simple
case of a chimney of ventilation for carrying off foul air from a
factory of any kind; and suppose that the tunnel of iron be incased
throughout with steam at 212 degrees Fahr. Suppose this tunnel to be 100
yards high, then the weight of the column of air in it will be to that
of a column of external air 100 yards high, assumed at 32° F. inversely
as its expansion by 180°; that is, as 1000 is to 1·375; or as 72·727 is
to 100. The column of external air at 32° being 100 yards, the internal
column will be represented by 72·727; and the difference = 27·27, will
be the amount of unbalanced weight or pressure, which is the effective
cause of the ventilation. Calculating the velocity of current due to
this difference of weight by the well-known formula for the fall of
heavy bodies, that is to say, multiplying the above difference, which is
27·27, by the constant factor 19·62, and extracting the square root of
the product; thus, √(19·62 × 27·27) = 23·13 will be the velocity in
yards per second, which, multiplied by 3, gives 69·39 feet. The quantity
of air which passes in a second is obtained of course by multiplying the
area or cross section of the tunnel by this velocity. If that section is
half a yard, that is = a quadrangle 2-1/4 feet by 2, we shall have 23·13
× 0·5 = 11·565 cubic yards, = 312-1/4 cubic feet.

The problem becomes a little more complicated in calculating the
velocity of air which has served for combustion, because it has changed
its nature, a variable proportion of its oxygen gas of specific gravity
1·111, being converted into carbonic acid gas of specific gravity 1·524.
The quantity of air passed through well-constructed furnaces may, in
general, be regarded as double of what is rigorously necessary for
combustion, and the proportion of carbonic acid generated, therefore,
not one half of what it would be were all the oxygen so combined. The
increase of weight in such burned air of the temperature of 212°, over
that of pure air equally heated, being taken into account in the
preceding calculation, will give us about 19 yards or 57 feet per second
for the velocity in a chimney 100 yards high incased in steam.

Such are the deductions of theory; but they differ considerably from
practical results, in consequence of the friction of the air upon the
sides of the chimneys, which varies likewise with its form, length, and
quality. The direction and force of the winds also exercise a variable
influence upon chimney furnaces differently situated. In chimnies made
of wrought iron, like those of steam boats, the refrigeration is
considerable, and causes a diminution of velocity far greater than what
occurs in a factory stalk of well-built brick work. In comparing the
numbers resulting from the trials made on chimneys of different
materials and of different forms, it has been concluded that the
obstruction to the draught of the air, or the deduction to be made from
the theoretical velocity of efflux, is directly proportional to the
length of the chimneys and to the square of the velocity, and inversely
to their diameter. With an ordinary wrought-iron pipe, of from 4 inches
to 5 inches diameter, attached to an ordinary stove, burning good
charcoal, the difference is prodigious between the velocity calculated
by the above theoretical rule, and that observed by means of a
stop-watch, and the ascent of a puff of smoke from a little tow, dipped
in oil of turpentine thrust quickly into the fire. The chimney being 45
feet high, the temperature of the atmosphere 68° Fahr., the velocity per
second was,--

  Trials.   By theory.   By experiment.   Mean temperature
                                            of chimney.
  1         26·4 feet      5    feet         190° Fahr.
  2         29·4           5·76              214
  3         34·5           6·3               270

To obtain congruity between calculation and experiment, several
circumstances must be introduced into our formulæ. In the first place,
the theoretical velocity must be multiplied by a factor, which is
different according as the chimney is made of bricks, pottery, sheet
iron, or cast iron. This factor must be multiplied by the square root of
the diameter of the chimney (supposed to be round), divided by its
length, increased by four times its diameter. Thus, for pottery, its
expression is 2·06√(D/(L + D)); D being the diameter, and L the length
of the chimney.

A pottery chimney, 33 feet high, and 7 inches in diameter, when the
excess of its mean temperature above that of the atmosphere was 205°
Fahr., had a pressure of hot air equal to 11·7 feet, and a velocity of
7·2 feet per second. By calculating from the last formula, the same
number very nearly is obtained. In none of the experiments did the
velocity exceed 12 feet per second, when the difference of temperature
was more than 410° Fahr.

Every different form of chimney would require a special set of
experiments to be made for determining the proper factor to be used.

This troublesome operation may be saved by the judicious application of
a delicate differential barometer, such as that invented by Dr.
Wollaston; though this instrument does not seem to have been applied by
its very ingenious author in measuring the draughts or ventilating
powers of furnaces.

If into one leg of this differential syphon, water be put, and fine
spermaceti oil into the other, we shall have two liquids, which are to
each other in density as the numbers 8 and 7. If proof spirit be
employed instead of water, we shall then have the relation of very
nearly 20 to 19. I have made experiments on furnace draughts with the
instrument in each of these states, and find the water and oil syphon to
be sufficiently sensible: for the weaker draughts of common fire-places
the spirits and oil will be preferable barometric fluids.

To the lateral projecting tube of the instrument, as described by Dr.
Wollaston, I found it necessary to attach a stop-cock, in order to cut
off the action of the chimney, while placing the syphon, to allow of its
being fixed in a proper state of adjustment, with its junction line of
the oil and water at the zero of the scale. Since a slight deviation of
the legs of the syphon from the perpendicular, changes very considerably
the line of the level, this adjustment should be made secure by fixing
the horizontal pipe tightly into a round hole, bored into the chimney
stalk, or drilled through the furnace door. On gently turning the
stop-cock, the difference of atmospherical pressure corresponding to the
chimney draught, will be immediately indicated by the ascent of the
junction-line of the liquids in the syphon. This modification of
apparatus permits the experiment to be readily rectified by again
shutting off the draught, when the air will slowly re-enter the syphon;
because the projecting tube of the barometer is thrust into the
stop-cock, but not hermetically joined; whereby its junction line is
allowed to return to the zero of the scale in the course of a few
seconds.

Out of many experiments made with this instrument, I shall content
myself with describing a few, very carefully performed at the breweries
of Messrs. Trueman, Hanbury, and Buxton, and of Sir H. Meux, Bart., and
at the machine factory of Messrs. Braithwaite; in the latter of which I
was assisted by Captain Ericsson. In the first trials at the breweries,
the end of the stop-cock attached to the differential barometer was
lapped round with hemp, and made fast into the circular peep-hole of the
furnace door of a wort copper, communicating with two upright parallel
chimneys, each 18 inches square, and 50 feet high. The fire was burning
with fully its average intensity at the time. The adjustment of the
level being perfect, the stop-cock orifice was opened, and the junction
level of the oil and water rose steadily, and stood at 1-1/4 inches,
corresponding to 1·25/8 = 0·156 of 1 inch of water, or a column of air
10·7 feet high. This difference of pressure indicates a velocity of 26
feet per second. In a second set of experiments, the extremity of the
stop-cock was inserted into a hole, bored through the chimney stalk of
the boiler of a Boulton and Watt steam-engine of twenty-horse power. The
area of this chimney was exactly 18 inches square at the level of the
bored hole, and its summit rose 50 feet above it. The fire-grate was
about 10 feet below that level. On opening the stop-cock, the junction
line rose 2-1/4 inches. This experiment was verified by repetition upon
different days, with fires burning at their average intensity, and
consuming fully 12 lbs. of the best coals hourly for each horse’s power,
or nearly one ton and a third in twelve hours. If we divide the number
2-1/4 by 8, the quotient 0·28 will represent the fractional part of 1
inch of water, supported in the syphon by the unbalanced pressure of the
atmosphere in the said chimney; which corresponds to 19-1/4 feet of air,
and indicates a velocity in the chimney current of 35 feet per second.
The consumption of fuel was much more considerable in the immense grate
under the wort copper, than it was under the steam-engine boiler.

In my experiments at Messrs. Braithwaite’s factory, the maximum
displacement of the junction line was 1 inch, when the differential oil
and water barometer was placed in direct communication with a chimney 15
inches square, belonging to a steam boiler, and when the fire was made
to burn so fiercely, that, on opening the safety-valve of the boiler,
the excess of steam beyond the consumption of the engine, rushed out
with such violence as to fill the whole premises. The pressure of
one-eighth of an inch of water denotes a velocity of draught of 23·4
feet per second.

In building chimneys, we should be careful to make their area rather too
large than too small; because we can readily reduce it to any desired
size, by means of a sliding register plate near its bottom, or a damper
plate applied to its top, adjustable by wires or chains, passing over
pulleys. Wide chimneys are not so liable as narrow ones to have their
draught affected by strong winds. In a factory, many furnace flues are
often conducted into one vertical chimney stalk, with great economy in
the first erection, and increased power of draught in the several fires.

Vast improvements have been made in this country, of late years, in
building stalks for steam boilers and chemical furnaces. Instead of
constructing an expensive, lofty scaffolding of timber round the
chimney, for the bricklayers to stand upon, and to place their
materials, pigeon-holes, or recesses, are left at regular intervals, a
few feet apart, within the chimney, for receiving the ends of stout
wooden bars, which are laid across, so as to form a species of temporary
ladder in the interior of the tunnel. By means of these bars, with the
aid of ropes and pulleys, every thing may be progressively hoisted, for
the building of the highest engine or other stalks. An expert
bricklayer, with a handy labourer, can in this way raise, in a few
weeks, a considerable chimney, 40 feet high, 5 feet 8 inches square
outside, 2 feet 8 inches inside at the base, 28 inches outside, and 20
inches inside at the top. To facilitate the erection, and at the same
time increase the solidity of an insulated stalk of this kind, it is
built with three or more successive plinths, or recedures, as shown in
_fig._ 281. It is necessary to make such chimneys thick and substantial
near the base, in order that they may sustain the first violence of the
fire, and prevent the sudden dissipation of the heat. When many flues
are conducted into one chimney stalk, the area of the latter should be
nearly equal to the sum of the areas of the former, or at least of as
many of them as shall be going simultaneously. When the products of
combustion from any furnace must be conducted downwards, in order to
enter near the bottom of the main stalk, they will not flow off until
the lowest part of the channel be heated by burning some wood shavings
or straw in it, whereby the air syphon is set agoing. Immediately after
kindling this transient fire at that spot, the orifice must be shut by
which it was introduced; otherwise the draught of the furnace would be
seriously impeded. But this precaution is seldom necessary in great
factories, where a certain degree of heat is always maintained in the
flues, or, at least, should be preserved, by shutting the damper plate
of each separate flue, whenever its own furnace ceases to act. Such
chimneys are finished at top with a coping of stone-slabs, to secure
their brickwork against the infiltration of rains, and they should be
furnished with metallic conducting rods, to protect them from explosions
of lightning.

When small domestic stoves are used, with very slow combustion, as has
been recently proposed, upon the score of a misjudged economy, there is
great danger of the inmates being suffocated or asphyxied, by the
regurgitation of the noxious burned air. The smoke doctors who recommend
such a vicious plan, from their ignorance of chemical science, are not
aware that the carbonic acid gas, of coke or coal, must be heated 250°
F. above the atmospheric air, to acquire the same low specific gravity
with it. In other words, unless so rarefied by heat, that gaseous poison
will descend through the orifice of the ash-pit, and be replaced by the
lighter air of the apartment. Drs. Priestley and Dalton have long ago
shown the co-existence of these two-fold crossing currents of air, even
through the substance of stone-ware tubes. True economy of heat, and
salubrity, alike require vivid combustion of the fuel, with a somewhat
brisk draught inside of the chimney, and a corresponding abstraction of
air from the apartment. Wholesome continuous ventilation, under the
ordinary circumstances of dwelling houses, cannot be secured in any
other way. Were these mephitic stoves, which have been of late so
ridiculously puffed in the public prints, generally introduced, the
faculty would need to be immediately quadrupled to supply the demand
for medical advice; for headaches, sickness, nervous ailments, and
apoplexy, would become the constant inmates of every inhabited mansion.
The phenomena of the grotto of Pausilippo might then be daily realised
at home, among those who ventured to recline upon sofas in such
carbonated apartments; only instead of a puppy being suffocated _pro
tempore_, human beings would be sacrificed, to save two-penny worth of
fuel _per diem_.

[Illustration: 281]

The figures upon the preceding page represent one of the two chimneys,
recently erected at the Camden Town station, for the steam boilers of
the two engines of 60 horse-power each, belonging to the London and
Birmingham Railway Company. These engines draw their train of carriages
up the inclined plane of Hampstead Hill. The chimneys were designed by
Robert Stephenson, Esq., engineer to the Company, executed by William
Cubitt, Esq., of Gray’s Inn Road,--and do equal honour to both
gentlemen, being probably the most elegant and substantial specimens of
this style of architecture in the world. In the section, _fig._ 281.,

A represents a bed of _concrete_, 6 feet thick, and 24 feet square.

B, brick footings set in cement; the lower course 19 feet square.

C, Bramley-fall stone base, with a chain of wrought iron let into it.

D, a portion, 15 feet high, curved to a radius of 113 feet, built
entirely of Malm paviours, (a peculiarly good kind of bricks.)

E, shaft built of Malm paviours in mortar.

F, ditto, built from the inside, without exterior scaffolding.

G, the cap ornamented, (as shown in the plan alongside,) with Portland
stone, the dressings being tied together with copper cramps and an iron
bond.

[Illustration: 282]

_Fig._ 282. represents the mouldings of the top, upon an enlarged scale.

[Illustration: 283]

_Fig._ 283., a plan of the foundation, ditto.

[Illustration: 284]

_Fig._ 284., ditto, at the level of the entrance of the flue, as seen in

[Illustration: 285]

_Fig._ 285., the elevation of the chimney.

[Illustration: 286]

_Fig._ 286., plan at the ground level I, in _fig._ 281. and 285.

K, _fig._ 281., the lightning conducting rod.


CHINTZ is a peculiar style of fast-printed calico, in which figures of
at least five different colours are impressed upon a white or light
coloured ground.


CHLORATE OF POTASH, commonly called oxymuriate of potash. This
interesting saline compound has become the object of a pretty extensive
manufacture, in consequence of its application to make matches for
procuring instantaneous light, and a detonating powder for fire-arms. It
may be prepared both in the humid and dry way.

Having made a strong solution of purified potash, or carbonate of
potash, with from two to three parts of water, we pass through it in a
Woulfe’s apparatus a current of chlorine gas, till it ceases to absorb
any more. Chloride of potash and chloride of potassium alone are formed
as long as there is an excess of alkali in the solution; but afterwards
in the further reaction of the materials, the chloride passes into the
state of a chlorate, and, as such, precipitates from the solution.
During the first half of the operation, that is, till the potash be
about one half saturated with chlorine, as indicated by litmus paper
ceasing to be darkened and beginning to be blanched, only the chloride
of potassium or muriate of potash falls. The process should be
interrupted at this point in order to remove the salt, to wash it, to
add the washings to the liquor, and then to transmit the gas freely
through the solution. As the operation advances, less muriate of potash
is formed, and at length nothing but the pure chlorate is separated in
crystals. When finally the bubbles of gas pass through without being
sensibly absorbed, the process is known to be completed; the liquid may
then be allowed to settle, and be poured off from the crystals of
chlorate of potash, which are purified from the muriate by dissolving
them in three times their weight of boiling water, and filtering the
solution while hot. On its cooling, the chlorate will separate in
pearly-looking crystalline plates. It may be rendered quite pure by a
second crystallization, in which state it does not affect solution of
nitrate of silver.

The above potash lye usually gets a reddish tint in the course of the
process in consequence of a little manganesic acid coming over with the
chlorine, but it gradually loses this colour as the saturation becomes
complete, when the solution turns yellow. The tubes for conveying the
gas should be of large diameter, if they be plunged into the saline
solution, because the crystallization which takes place in it is apt to
choke them up. This inconvenience may however be obviated by attaching
to the end of the glass tube, a tube of caoutchouc terminated in a small
glass funnel, or simply the neck of a caoutchouc bottle with a part of
its body, whose width will not be readily closed with a saline crust.
The residuary lixivium may be used against another operation, or it may
be evaporated down to half its bulk and set aside to crystallize,
whereby some more chlorate will be obtained, mixed indeed with muriate
and carbonate, from which however it may be separated by a second
crystallization. In general the pure chlorate obtained does not exceed
one tenth the weight of the potash employed; because in thus treating
potash with chlorine, five-sixths of it are converted into muriate of
potash and only one sixth into chlorate, and a part of the latter
adheres to the muriate, or is lost in the mother waters of the
crystallizations.

The chlorate of potash may be more conveniently manufactured, like that
of lime, in the dry way. St. Romer patented at Vienna the following
method for that purpose in 1821:--Ten pounds of crystallised peroxide of
manganese are to be finely pulverised, mixed with ten pounds of
plumbago, and thirty pounds of common salt, and put into the leaden
retort represented in _fig._ 287. p. 287. From the middle of the
helmet-shaped lid of this vessel, a lead tube, two feet long and two
inches wide, conducts to the receiver, which is a square earthen pan,
hard glazed both within and without, of the same capacity with the
retort. The end of the tube must be made fast to a frame at the height
of six inches above the bottom of the receiver. Upon its inner sides
four inches apart, brackets are to be fixed for supporting a series of
laths or shelves of white wood, on which a number of little paper or
paste-board boxes are to be laid. In these boxes ten pounds of the
purest carbonate of potash, prepared from tartar, are to be spread. The
receiver must now be covered with a lid made tight by a water lute.
Twenty pounds of concentrated sulphuric acid previously diluted with
sixteen pounds of water, and then cooled, are to be poured upon the
mixed materials in the retort, the lid immediately secured, with the
tube adjusted in the receiver. The whole must be allowed to operate
spontaneously without heat for twelve hours. At the end of this time the
retort is to be surrounded with a water bath and steadily heated during
twelve hours, and then left to cool for six hours. The apparatus must
now be opened, the cakes of chlorate of potash removed, and freed from
muriate by solution and crystallization.

M. Liebig proposes the following process for obtaining chlorate of
potash:--

Heat chloride of lime in water till it ceases to destroy vegetable
colours. In this case a mixture of chloride of calcium and chlorate of
potash is obtained. This is to be dissolved in hot water, and to the
solution concentrated by evaporation, chloride of potassium is to be
added, and then suffered to cool. After cooling, a quantity of crystals
of chlorate of potash is obtained, which are to be redissolved and
crystallized again to purify them. M. Liebig considers that this will be
a cheap process for obtaining chlorate of potash. From 12 ounces of
chloride of lime, of so bad a quality that it left 65 per cent. of
insoluble matter, he obtained an ounce of chlorate of potash.

The only difficulty to overcome in this process is, from the chloride of
lime not being so easily decomposed by heat as is generally supposed; a
solution of it may be kept boiling for an hour without losing its
bleaching power. The best method is to form a thin paste with chloride
of lime and water, and then to evaporate it to dryness. If it be
required to prepare it by passing chlorine into cream of lime, it is
advantageous to keep it very hot.

The chlorate of potash which separates from the solution by
crystallization, has not the form of scales which it usually possesses,
but is prismatic: whether this is occasioned by some admixture has not
been ascertained; but on re-crystallizing, it is obtained in the usual
form.

The solution ought not merely to be left to cool, in order to procure
crystals, for the crystallization is far from being terminated even
after complete cooling; crystals continue to be deposited for 3 or 4
days.

The following modification of the process for making chlorate of potash
is that of M. Vée. A solution of chloride of lime marking 18° or 20°
Baumé, is to be set upon the fire in a lead or cast iron pot, and when
it begins to get hot, there is to be dissolved in it, a quantity of
chloride of potassium sufficient to raise the hydrometer 3 or 4 degrees.
It must be then concentrated as quickly as possible till it marks 30° or
31°, taking care that it does not boil over by the sudden extrication of
oxygen. The concentrated liquor is set aside to crystallize in a cool
place; where a deposit of chlorate of potash forms, mixed with chloride
of potassium. The mother waters being evaporated to the density of 36°,
afford another crop of crystals, after which they may be thrown away.

The salts obtained at the first crystallization are to be re-dissolved,
and the solution being brought to 15° or 16° is to be filtered, when it
will afford upon cooling pure chlorate of potash.

Chlorate or oxymuriate of potash has a cooling, somewhat unpleasant and
nitrous taste. It does not bleach. At 60° F. 100 parts of water dissolve
six parts of it, and at its boiling point or 220°, sixty parts. When
heated to dull ignition in a glass retort it gives out 39·15 per cent.
of its weight of oxygen, and becomes thereby chloride of potassium. When
strongly triturated in a mortar it crackles, throws out sparks, and
becomes luminous. It deflagrates upon red-hot cinders like nitre: when
triturated along with sulphur, or phosphorus, it detonates with great
violence, not without danger to the hands of the operator, if they be
not protected by a thick glove. Similar detonations may be produced with
cinnabar or vermillion, sulphuret of potassium, sugar, volatile oils,
&c.; but they can be effected only by the smart blow of a heated hammer
and anvil. A mixture of sugar or starch with chlorate of potash is
readily inflamed by a drop of sulphuric acid, and this experiment is the
basis of the preparation of the oxygenated matches, as they have been
commonly called. The following formula forms a good paste for tipping
the said matches, made of narrow slips of either wood or card. Thirty
parts of the chlorate in fine powder are to be mixed gently with a
spatula upon paper with ten parts of flowers of sulphur well levigated,
eight of sugar, five of gum arabic, and enough of vermillion to give the
whole a rose tint. We begin by mixing tenderly together the sugar, the
gum, and the salt previously pulverised; we then add as much water as
shall reduce the mixture to a thin paste, and lastly introduce the
sulphur; after which all must be well incorporated. The points of the
matches, either previously tipped with sulphur or not, are to be dipped
in that paste, so as to get coated with a little of it, and are lastly
laid in a warm place till they become thoroughly dry. To kindle one of
them, it must be touched with strong sulphuric acid, which for this
purpose is usually kept in a small well-stoppered phial, and thickened
with amianthus. Aspen is reckoned the best wood for matches.

Of late years a detonating priming for fire-arms has been much used with
the percussion locks. The simplest formula for making it is to take ten
parts of gunpowder, to lixiviate it with water, and to mix the residuum,
while moist, with five parts and a quarter of chlorate of potash,
reduced to an extremely fine powder. The paste may be made pretty thin,
for the salt is sparingly soluble in the cold water, and it mixes best
when tolerably fluid. This powder when dry is dangerous to handle, being
very apt to explode. But this danger is guarded against by letting fall
a drop of the paste into each copper percussion cap, and leaving it to
dry there. In the detonation of this powder, besides muriate of potash,
there are generated a little sulphate of potash and chlorine gas, which
rust the metal very fast. For which reason fulminate of mercury is now
preferred by many sportsmen as a detonating powder. See FULMINATE.


CHLORATES, compounds of chloric acid with the salifiable bases. The only
acid belonging to this class of any manufacturing importance is the
following:


CHLORIC ACID; the acid constituent of the preceding salt; it consists of
one equivalent prime of chlorine = 35·476, + 5 of oxygen, = 40·065; of
which the sum 75·535 is the prime equivalent of the acid.


CHLORINE; the most energetic of the undecompounded bodies, or chemical
elements as they are usually called, exists, under ordinary
circumstances, as a greenish yellow gas, but, when exposed to a pressure
of 4 atmospheres, it becomes a yellow transparent liquid. In the first
state, its density compared to air, reckoned 1·000, is 2·47; in the
second, its density compared to water, 1·000, is 1·33. No degree of
cold, hitherto tried, has liquefied the gas when dry. It is obtained by
putting into a glass retort a mixture of 3 parts of common salt, with 2
parts of peroxide of manganese, and pouring upon it 2 parts of sulphuric
acid diluted with its own weight of water; or, more conveniently, by
pouring moderately strong muriatic acid upon peroxide of manganese in a
retort; and in either case applying the gentle heat of a spirit lamp or
a water bath, while the beak of the retort is plunged under brine upon
the shelf of the pneumatic trough. The gas issues, and may be received
in the usual way into inverted glass jars, or phials; but the first
which comes over being mixed with the air of the retort, must be
rejected. It has a peculiar smell, and irritates the nostrils most
violently when inhaled, as also the windpipe and lungs. It is eminently
noxious to animal life, and, if breathed in its undiluted state, would
prove instantly fatal. It supports the combustion of many bodies, and
indeed spontaneously burns several without their being previously
kindled. The resulting combinations are called chlorides, and act most
important parts in many manufacturing processes.

Water absorbs, at the ordinary temperature of the atmosphere, about
double its volume of chlorine, and acquires the colour, smell, and taste
of the gas, as well as its power of destroying or bleaching vegetable
colours. When this aqueous chlorine is cooled to 36° F. dark yellow
crystalline plates appear in it of the hydrate of chlorine, which are
composed in 100 parts of 27·7 chlorine, and 72·3 water. If these
crystals be heated to about 45° they liquefy, and the gas flies off.

Chlorine has a powerful affinity for hydrogen, not only combining with
it rapidly in the gaseous, but seizing it in many of its liquid and
solid combinations, as in volatile oils, which it inflames, and in
yellow wax, cotton, and flax, which it whitens. The compound of chlorine
and hydrogen gases is muriatic acid gas. Manganese, when mixed with
liquid muriatic acid, as in the above process, abstracts the hydrogen,
and lets the chlorine gas go free. When chlorine is passed into water,
it decomposes some of it, seizes its hydrogen to form a little muriatic
acid, and enables its oxygen to unite either with the chlorine, into
chlorous acid, or with the remaining water, and to constitute oxygenated
water. Hence, aqueous chlorine, exposed to the sunbeam, continually
evolves oxygen, and, ere long, becomes muriatic acid.

This watery compound acts in a powerful way upon coloured vegetable
fibres, extracting their hydrogen or colouring element by the twofold
affinities of the chlorine and oxygen for it.

Hence chlorine, as a bleaching agent, requires to be tempered by the
quiescent affinity of some alkaline base, potash or lime. Malaria, or
morbific and putrescent miasmata, consist chiefly of hydrogenous matter
as their basis, and are best counteracted by chlorine, where it can be
conveniently applied.

_Chlorides of Potash, Soda, and Lime._--These are the most important
preparations through which chlorine exercises its peculiar powers upon
the objects of manufactures. When a weak solution of caustic potash or
soda is saturated with chlorine, it affords a bleaching liquor which is
still used by some bleachers and calico-printers for their most delicate
processes; but the price of the alkalis has led to the disuse of these
chlorides as a general means, and has occasioned an extensive employment
of chloride of lime. Upon the manufacture of this interesting compound I
made an elaborate series of experiments several years ago, and published
the results in the 13th volume of Brande’s Journal, for April 1822. I
have no reason to suppose, from any thing that has been published since,
that the processes there described have been essentially improved, or
that any errors, either theoretical or practical, of any moment, exist
in that memoir. I shall therefore first present my readers with a brief
abstract of it, and then make such observations as subsequent inquiries
suggest.

In the researches which I made, at many different times, upon the nature
of the chloride of lime, I generally sought to combine the information
flowing from both synthesis and analysis; that is, I first converted a
known portion of hydrate of lime into bleaching-powder, and then
subjected this chloride to analysis.

Two hundred grains of the atomic proto-hydrate of pure lime were put
into a glass globe, which was kept cold by immersion in a body of water
at 50°. A stream of chlorine, after being washed in water of the same
temperature in another glass globe, connected to the former by a long
narrow glass tube, was passed over the calcareous hydrate. The globe
with the lime was detached from the rest of the apparatus from time to
time, that the process might be suspended as soon as the augmentation of
weight ceased. This happened when the 200 grains of hydrate, containing
151·9 of lime, had absorbed 130 grains of chlorine. By one analytical
experiment it was found, that dilute muriatic acid expelled from 50
grains of the chloride, 20 grains of chlorine, or 40 per cent.; and by
another, from 40 grains, 16·25 of gas, which is 40·6 per cent. From the
residuum of the first 39·7 grains of carbonate of lime were obtained by
carbonate of ammonia; from that of the second, 36·6 of ignited muriate
of lime. The whole results are therefore as follows:--

  +--------+----------+-------------+------------+------+
  |        |Synthesis.|1st Analysis.|2d Analysis.| Mean.|
  |        +----------+-------------+------------+------+
  |Chlorine|  39·39   |    40·00    |    40·62   | 40·31|
  |Lime    |  46·00   |    44·74    |    46·07   | 45·50|
  |Water   |  14·60   |    15·26    |    13·31   | 14·28|
  |        | ------   |   ------    |   ------   |------|
  |        | 100·00   |   100·00    |   100·00   |100·00|
  +--------+----------+-------------+------------+------+

Though the heat generated by the action of the dilute acid had carried
off in the analytical experiments a small portion of moisture with the
chlorine, yet their accordance with the synthetic experiment is
sufficiently good to confirm the general results. The above powder
appears to have been a pure chloride, without any mixture of muriate.
But it exhibits no atomic constitution in its proportions.

To 200 grains of that hydrate of lime 30 grains of water being added,
the powder was subjected to a stream of chlorine in the above way, till
saturation took place. Its increase of weight was 150 grains.

It ought to be remarked, that in this and the preceding experiment,
there was no appreciable pneumatic pressure employed to aid the
condensation of the chlorine. In the last case, we see that the addition
of 30 grains of water has enabled the lime to absorb 20 grains more of
chlorine, being altogether a quantity of gas nearly equal to that of the
dry lime. Thus, an atom of lime seems associated with 7/9 of an atom of
chlorine. Analysis by muriatic acid confirmed this composition. It gave

  Chlorine    39·5 = 51·8 cubic inches.
  Lime        39·9
  Water       20·6
             -----
             100·0
             -----

A great variety of apparatus has been at different times contrived for
favouring the combination of chlorine with the slacked lime for the
purposes of commerce. One of the most ingenious forms, is that of a
cylinder, or barrel, furnished with narrow wooden shelves within, and
suspended on a hollow axis by which the chlorine was admitted, and round
which the barrel was made to revolve. By this mode of agitation, the
lime-dust being exposed on the most extensive surface, was speedily
impregnated with the gas to the requisite degree. Such a mechanism I saw
at MM. Oberkampf and Widmer’s celebrated _fabrique de toiles peintes_,
at Jouy, in 1816. But this is a costly refinement, inadmissible on the
largest scale of British manufacture. The simplest, and, in my opinion,
the best construction for subjecting lime-powder to chlorine, is a large
chamber 8 or 9 feet high, built of siliceous sandstone, having the
joints of the masonry secured with a cement composed of pitch, resin,
and dry gypsum in equal parts. A door is fitted into it at one end,
which can be made air-tight by strips of cloth and clay lute. A window
on each side enables the operator to judge how the impregnation goes on
by the colour of the air, and also gives light for making the
arrangements within at the commencement of the process. As water lutes
are incomparably superior to all others where the pneumatic pressure is
small, I would recommend a large valve or door on this principle to be
made in the roof, and two tunnels of considerable width at the bottom of
each side wall. The three covers could be simultaneously lifted off by
cords passing over a pulley, without the necessity of the workman
approaching the deleterious gas, when the apartment is to be opened. A
great number of wooden shelves, or rather trays, 8 or 10 feet long, 2
feet broad, and 1 inch deep, are provided to receive the riddled slacked
lime, containing generally about 2 atoms of lime to 3 of water. These
shelves are piled one over another in the chamber, to the height of 5 or
6 feet, cross bars below each keeping them about an inch asunder, that
the gas may have free room to circulate over the surface of the
calcareous hydrate.

The alembics for generating the chlorine, which are usually nearly
spherical, are in some cases made entirely of lead, in others of two
hemispheres, joined together in the middle, the upper hemisphere being
lead, the under one cast-iron. The first kind of alembic is enclosed for
two-thirds from its bottom, in a leaden or iron case, the interval of
two inches between the two being destined to receive steam from an
adjoining boiler. Those which consist below of cast-iron, have their
bottom directly exposed to a very gentle fire; round the outer edge of
the iron hemisphere a groove is cast, into which the under edge of the
leaden hemisphere fits, the joint being rendered air-tight by Roman or
patent cement. In this leaden dome there are four apertures, each
secured by a water-lute. The first opening is about 10 or 12 inches
square, and is shut with a leaden valve, with incurvated edges, that fit
into the water channel at the margin of the hole. It is destined for the
admission of a workman to rectify any derangement in the apparatus of
rotation, or to detach hard concretions of salt from the bottom.

The second aperture is in the centre of the top. Here a tube of lead is
fixed, which descends nearly to the bottom, and down through which the
vertical axis passes. To its lower end the cross bars of iron, or of
wood, sheathed with lead, are attached, by whose revolution the
materials receive the proper agitation for mixing the dense manganese
with the sulphuric acid and salt. The motion is communicated either by
the hand of a workman applied from time to time to a winch at top, or it
is given by connecting the axis with wheel work, impelled by a stream of
water or a steam-engine. The third opening admits the syphon-formed
funnel, through which the sulphuric acid is introduced; and the fourth
is the orifice of the eduction-pipe.

Manufacturers differ much from each other in the proportion of their
materials for generating chlorine. In general, 10 cwt. of salt are mixed
with from 10 to 14 cwt. of manganese, to which mixture, after its
introduction into the alembic, from 12 to 14 cwt. of sulphuric acid are
added in successive portions. That quantity of oil of vitriol must,
however, be previously diluted with water, till its specific gravity
becomes about 1·6. But, indeed, this dilution is seldom actually made,
for the manufacturer of bleaching-powder almost always prepares his own
sulphuric acid for the purpose, and therefore carries its concentration
no higher in the leaden boilers than the density of 1·65, which from my
table of sulphuric acid, indicates 1/4th of its weight of water, and
therefore 1/3d more of such acid must be used.

The fourth aperture, I have said, admits the eduction pipe. This pipe is
afterwards conveyed into a leaden chest or cylinder, in which all the
other eduction pipes also terminate. They are connected with it simply
by water-lutes, having a hydrostatic pressure of 2 or 3 inches. In this
general _diversorium_ the chlorine is washed from adhering muriatic
acid, by passing through a little water, in which each tube is immersed,
and from this the gas is let off by a pretty large leaden tube, into the
combination room. It usually enters in the top of the ceiling, whence it
diffuses its heavy gas equally round.

Four days are required, at the ordinary rate of working, for making good
marketable bleaching-powder. A more rapid formation would merely
endanger an elevation of temperature, productive of muriate of lime, at
the expense of the bleaching quality. But skilful manufacturers use here
an alternating process. They pile up, first of all, the wooden trays
only in alternate shelves in each column. At the end of two days the
distillation is intermitted, and the chamber is laid open. After two
hours the workman enters, to introduce the alternate trays covered with
fresh hydrate of lime, and at the same time rakes up thoroughly the
half-formed chloride in the others. The door is then secured, and the
chamber, after being filled for two days more with chlorine, is again
opened, to allow the first set of trays to be removed, and to be
replaced by others, containing fresh hydrate, as before. Thus the
process is conducted in regular alternation; thus, to my knowledge,
very superior bleaching-powder is manufactured, and thus the chlorine
may be suffered to enter in a pretty uniform stream. But for this
judicious plan, as the hydrate advances in impregnation, its faculty of
absorption becoming diminished, it would be requisite to diminish
proportionately the evolution of chlorine, or to allow the excess to
escape to the great loss of the proprietor, and, what is of more
consequence, to the great detriment of the health of the workmen.

The manufacturer generally reckons on obtaining from one ton of
rock-salt, employed as above, a ton and a half of good bleaching-powder.
But the following analysis of the operation will show that he ought to
obtain two tons.

When a mixture of sulphuric acid, common salt, and black oxide of
manganese are the ingredients used, as by the manufacturer of
bleaching-powder, the absolute proportions are, upon the oxygen scale of
equivalents:--

  1 atom muriate of soda             7·5     29·70    100·0
  1 atom peroxide of manganese       5·5     21·78     73·3
  2 atoms oil of vitriol 1·846     12·25     48·52    163·3
                                  ------    ------
                                   25·25    100·00

And the products ought to be:--

  Chlorine disengaged              1 atom.    4·5      17·82
  Sulphate of soda                 1  --      9·0      35·64
  Proto-sulphate of manganese      1  --      9·5      37·62
  Water                            2  --      2·25      8·92
                                             -----    ------
                                             25·25    100·00

These proportions are, however, very different from those employed, by
many, nay I believe by all manufacturers; and they ought to be so, on
account of the impurity of their oxide of manganese. Yet making
allowance for this, I am afraid that many of them commit great errors in
the relative quantities of their materials.

From the preceding computation, it is evident that 1 ton of salt with 1
ton of the above native oxide of manganese properly treated, would yield
0·59 of a ton of chlorine, which would impregnate 1·41 tons of slaked
lime, producing 2 tons of bleaching-powder, stronger than the average of
the commercial specimens; or allowing for a little loss, which is
unavoidable, would afford 2 tons of ordinary powder, with a little more
slaked lime.

[Illustration: 287 288]

_Fig._ 287. represents a retort of lead, well adapted to the evolution
of chlorine from the mixture of salt, manganese, and sulphuric acid, or
from manganese and muriatic acid. The interior vessel is cast in lead,
and it has round its bottom part a cast-iron steam case. The salt and
manganese are introduced by the aperture C, and the sulphuric acid by
the syphon funnel F. The contact of these three substances is
continually renewed by the agitator or stirrer B, which consists of
wrought or cast iron sheathed with lead. _e_ is the gas discharge pipe.
The residuums are drawn off by the bottom discharge pipe G. The heating
case receives its steam by the pipe _h_.

The chlorine gas _fig._ 288. is conveyed from the retort B into the
chamber I, by the tube E E E. This chamber is divided into four
compartments, to receive the gas disengaged from four retorts, like the
above. The bottom of it is covered with a stratum three or four inches
thick of quicklime, newly slaked and sifted, which is stirred about
from time to time, by the rakes L L L L. When the saturation is
sufficient, the chloride of lime is taken out by the doors K K K K. The
size of this apparatus allows 2 cwt. of manganese, and its equivalent
quantity of salt and sulphuric acid, or of muriatic acid, to be
introduced at once into the retort. D is the handle of the agitator.

The same form of retort will suit perfectly well to prepare chlorine for
making liquid chloride of lime, which is preferred by many bleachers and
calico-printers who have conveniences for preparing it themselves. The
most concentrated solutions of the dry chloride of lime do not mark more
than 6° B. (sp. grav. 1·04), and discolour only 50 volumes of Gay
Lussac’s solution of indigo, whilst the chloride made in the humid way
marks from 8° to 9° B. (about 1·060), and discolours 80 volumes of the
same solution.

In the chloride of lime apparatus, most generally used by the skilful
calico-printers of Mulhausen, the mixture of muriatic acid and manganese
is put into glass globes, with long necks, heated upon a sand-bath. The
chlorine is conveyed by glass tubes into a cylindrical stone cistern,
containing milk of lime. The furnace of the sand baths is made of cast
iron, and has brick partitions, to give each retort its own fire. The
smoke of all these fires goes off by a flue into sheet iron pipes. The
cistern is made of siliceous sandstone. Its cover is of wood, coated
with a resinous cement; and it fits at its edges into grooves cut in the
stone. A wheel serves to agitate the liquid continually; its paddles
being kept at two inches distance from the sides of the cistern. The
milk of lime is introduced by a funnel, and the chloride is drawn off by
a discharge pipe. I think the lead retort and agitator used in this
country greatly preferable to the experimental laboratory plan described
above. In all such apparatus we should avoid giving any pressure to the
tubes or vessels, and should not therefore dip the extremities of the
gas pipes beneath the surface of the liquid, but rather facilitate the
combination of the chlorine and the lime, by enlarging the surfaces of
contact and by agitating. Intermediate vessels containing water, or the
chemical cascade of M. Clement, are very useful for absorbing any
muriatic acid which may be disengaged along with the chlorine, and
thereby preventing the needless formation of muriate of lime in the
chambers or cisterns of impregnation.

When the solution of the chloride of lime is mixed with hydrate of lime,
it bears, without decomposing, a pretty high temperature, provided it be
not too long continued; it may even, in certain cases, be raised to near
the boiling point without suffering a marked loss of its discolouring
power; but when the chloride is deprived of that excess of lime, it is
decomposed in a short time, even at a heat of 110° F.

When chlorine is admitted to milk of lime, it infallibly produces some
muriate of lime; but the quantity is kept at a _minimum_ by constantly
presenting an excess of lime to the gas with the agitator, and by
keeping the temperature as low as possible. Hence the influx of gas
should not be so rapid as to generate much heat. An automatic agitator,
moved by steam or water power, is therefore much better than one driven
by the hand of the operator, who is apt to intermit his labours. If the
liquor becomes hot at the end of the process, it should be immediately
drawn off into large stone bottles, and cooled. The rose-colour, which
sometimes supervenes, is due to a minute quantity of manganese. The
strongest liquid chloride of lime that can be prepared will not
discolour more than 80 times its volume of Gay Lussac’s indigo test.

On acting upon cotton cloth with a concentrated solution of chloride of
lime, at from 110° to 120° F., pure carbonic acid gas is disengaged, and
the texture of the cloth is injured. Here the hydrogen of the water and
the cotton being seized by the chlorine, the liberated oxygen combines
with the carbon to form carbonic acid. In the discharge troughs where
printed calicoes are passed through strong solutions of chloride of
lime, stalactitic crusts of carbonate of lime come to be formed in this
way.

The _chlorometre_ of Gay Lussac consists of a test solution of indigo
and a graduated tube. One part of the best indigo, passed through a silk
sieve, is to be dissolved in nine parts of concentrated sulphuric acid,
by the aid of a water-bath heat applied for six hours. The sulphate of
indigo is now to be diffused through such a body of water that one
volume of chlorine gas shall discolour exactly ten times its volume of
this dilute solution. The test liquor should be protected from the
agency of light.

Mr. Crum, of Thorniebank, near Glasgow, has lately modified Dr. Dalton’s
copperas test for chloride of lime, and made it convenient to the
practical man. The Doctor justly considered that the more chlorine any
bleaching powder contains, the more of the green sulphate of iron will
it convert into the red sulphate, so that we have only to add successive
portions of the chloride to a given weight of the dissolved copperas,
and note the point at which all the iron gets peroxidized. See
BLEACHING.

[Illustration: 289]

Besides the method of analysis already quoted from my memoir on the
manufacture of the chloride of lime, another occurred to me long ago,
which I often practised as an easy and expeditious test. Chlorine
decomposes ammonia. If therefore water of ammonia, faintly tinged with
litmus, be added slowly to a solution of a given weight of chloride of
lime, the colour will continue to disappear till the chlorine be all
neutralized by the reaction of the hydrogen of the ammonia. The quantity
of liquid ammonia of a certain strength requisite to neutralize in this
way, a certain volume, say, one cubic inch, or a thousand grain measures
of chlorine gas, may be assumed as the standard of such a chlorometer.
As chlorine or chloride of lime, when mixed with water of ammonia,
causes the disengagement of azote, the quantity of this gas evolved may
also be made the foundation of an accurate and convenient chlorometer.
The two substances should be mixed over mercury, in a graduated syphon
tube. The shut end A and the open end B are both graduated to one scale;
for example, to hundredths of a cubic inch, or to grain or 10 grain
measures. The tube is to be filled with mercury, and then 10 measures of
it are to be displaced at the open end, by inserting a wooden plug. This
space, being filled with the solution of chloride of lime, is to be
turned up into the shut end by covering the open end with the finger,
and inverting the tube; a few drops of water may be sent through to wash
the mercury. The ammonia being now let up, will cause a reaction, and
evolve a quantity of azote, equivalent to the chlorine present. The
action may be quickened by holding the sealed end of the tube obliquely
over a lamp heat. The mercury is protected from the chlorine by the
ammonia; and should any notion be entertained of such an action, the
ammonia may be let up first. I have made innumerable researches over
mercury with a detached apparatus of that kind, which combines precision
with rapidity of result. It was by a similar mercurial syphon that I
analyzed the carbonates, as described in the first edition of my
Dictionary of Chemistry, twenty-one years ago.

M. Gay Lussac takes, as the basis of his indigo chlorometer, the fact,
that one pound of pure crystallized peroxide of manganese is capable of
affording, with muriatic acid, 0·7964 parts of a pound of chlorine; or
one kilogramme yields 251-1/4 litres; that is, one pound yields 251-1/4
pound measures. Hence 3·98 grammes of that manganese are capable of
affording 1000 gramme measures, or 1 litre of chlorine; or, in round
numbers, 4 grains will yield 1000 grain measures. This quantity of gas,
being received into that volume of milk of lime, constitutes therefore
Gay Lussac’s primary standard. The small retort in which the manganese
and muriatic acid are put, ought to be heated to ebullition, to
discharge every particle of chlorine. To prevent the manganese, in this
experiment, from sticking to the bottom in a cake, it has been proposed
to mix it previously with a little plumbago. See CHLOROMETRY.

For preparing the chlorides of potash and soda, the same apparatus may
be employed as for the liquid chloride of lime. The alkaline solutions
should be weak, containing not more than a pound to the gallon of water.
Potash liquor saturated with chlorine, is much employed at Paris for
whitening linen, under the name of the water of Javelle, the place where
it was first made as a manufacture. One hundred parts of chlorine are
said to saturate 133 parts of pure potash, and 195 of the carbonate; but
the latter should not be used for preparing the bleaching fluid, as the
carbonic acid resists the combination of the chlorine. A chloride of
carbonate of soda has been lately recommended as a disinfecting
substance against contagious miasmata or _fomites_. One hundred parts of
chlorine will saturate 150 of the dry carbonate, and 405 of the
crystallized. M. Payen prepares this medicinal chloride by adding 138
parts of carbonate of soda to a liquid, consisting of water 1800,
chloride of lime 100, at 98° of strength, by Gay Lussac’s standard. The
chloride of lime is to be dissolved, and the sediment well washed; the
carbonate of soda, dissolved by heat, is to be poured into the solution,
the precipitate allowed to subside, the clear fluid decanted, and the
solid matter washed upon a filter. The collected solutions are neutral
chloride of soda. Sixty-two parts of the carbonate of soda are then to
be dissolved in the remainder of the water, and added to the
preparation; the whole being thus filtered, a limpid liquor is obtained,
indicating 5° by the hydrometer of Baumé.

The chloride of magnesia was long ago proposed by Sir H. Davy for
bleaching linen, as being preferable to chloride of lime, because the
resulting muriate of magnesia was not injurious to the fibre of cloth,
as muriate of lime may be, under certain circumstances. I prepared a
quantity of chloride of magnesia, by exposing a hydrate of that earth in
the chlorine chamber of a large manufactory of chloride of lime at
Glasgow, and obtained a compound possessed of considerable discolouring
powers; but I found that the chlorine was so feebly saturated by the
base, that it destroyed the colours of fast-dyed calicoes as readily as
chlorine gas or chlorine water did, and was therefore dangerous for
common bleaching, and destructive in clearing the grounds of printed
goods, which is one of the most valuable applications of the calcareous
and alkaline chlorides. The occasion of my making these experiments was
the importation of a considerable quantity of magnesite, or native
atomic carbonate of magnesia, from the district of Madras, by an
enterprising friend of mine. Encouraged by the encomiums bestowed on the
chloride of magnesia by many chemical writers, he expected to have
benefited both the country and himself, by bringing home the earthy base
of that compound, at a moderate price; but was disappointed to his cost.

Dr. Thomson is of opinion that the bleaching compound of lime and
chlorine is not a chloride of lime, but a combination of chlorous acid
with lime and of chlorine with calcium; consisting in its most
concentrated state of

  3 atoms of chloride of calcium = 21
  1 atom of chlorite of lime     = 11
                                  ---
                                   32
                                  ---

So that about one third of the weight is chlorite of lime, to which
alone the bleaching powers of the substance are owing. He admits a fact,
rather inconsistent with this opinion, that bleaching powder does not
attract moisture from the atmosphere with nearly so much rapidity as
might be expected from a mixture containing two thirds of its weight of
so deliquescent a salt as muriate of lime; unless this indeed be
prevented by the chloride and chlorite being united into a double salt,
which is a mere conjecture without either proof or analogy. And further,
when dilute sulphuric or muriatic acid is poured upon bleaching powder,
a profusion of chlorine is given out immediately, which he also admits
to be inconsistent with the notion of its being a mixture of chloride of
calcium and chlorite of lime, for no such evolution takes place when the
above acids are mixed with solutions of chloride of calcium and chlorate
of potash. Though I am of opinion that bleaching powder is simply a
chloride of lime, in which the lime corresponds to the water in the
aqueous chlorine, yet I cannot see the truth or appositeness of his last
reason, because chlorine is certainly given out when chlorate of potash
is acted upon by dilute muriatic acid, as any man may prove by adding to
a mixture of these two substances a vegetable colour; for it will be
speedily blanched. Dr. Thomson considers the chloride which is at
present made in Mr. Tennant’s great factory, as containing one atom of
chlorine associated with one atom of lime, or, taking his numbers, as
consisting of

  Hydrate of lime  4·625
  Chlorine         4·5

Or nearly equal weights of the chlorine and the base; indicating a
surprising degree of excellence in the preparation. The average
commercial samples of bleaching powder from different factories which I
examined some years ago, did not possess nearly that strength; but
varied in their quantity of chlorine from 20 to 28 per cent. In my
synthetic experiments related above, the greatest quantity of chlorine
that would combine with the atomic hydrate of lime, was in the
proportion of 130 to 200; but there is no doubt that if the lime
contains additional water, it will condense more gas. I have never seen
a chloride of lime of the strength mentioned by Dr. Thomson, and I
should think there must be some fallacy in his statements. I have
recorded in the paper above quoted an experiment which proves that with
additional moisture, a chloride of lime may be obtained of the following
composition:--

  Chlorine  39·5
  Lime      39·9
  Water     20·6
           -----
           100·0
           -----

In the article BLEACHING, of the Encyclopædia Britannica, Dr. Thomson
deduces from a test trial of Mr. Crum, that the best bleaching powder is
a compound of 1 atom chlorite of lime = 11, 3 atoms chloride of calcium
= 21, and 8 atoms of water = 9. “But,” adds he, “in general the whole
lime is not accurately saturated with chlorine. Accordingly, when the
bleaching powder is dissolved in water a small residue almost always
remains undissolved. Unless the powder be fresh made, a portion of
chlorite is always converted into chloride of calcium. It is probable
therefore that the best bleaching powder, as it comes into the hands of
the bleachers, consists of

  1 atom chlorite of lime      11
  3 atoms chloride of calcium  21
  6 atoms water                 6·75
    Impurity                    2·25
                               -----
                               41·00
                               -----

“If we consider the bleaching powder as a compound of chlorine and lime,
our mode of calculating will not be altered. Instead of 1 atom chlorite
of lime, and 3 atoms chloride of calcium, we shall have 4 atoms chloride
of lime, 6 atoms water, and 2·25 of impurity as before.” In such
ambiguity does this able chemist place this interesting compound, for
theoretical reasons, of which I cannot see the value. Surely there is no
difficulty in conceiving chlorine to exercise a direct attractive force
towards the hydrate of lime, as it is known to do towards each of its
elementary constituents, the oxygen and the calcium. Such refinements as
the preceding tend merely to mystify a plain matter. Even the chlorous
acid here brought into play to form the ideal chlorite, is by his own
admission a hypothetical being. “When chlorate of potash” says Dr.
Thomson, “is mixed with sulphuric acid, and made into small balls the
size of a pea, if we expose these balls to a heat somewhat lower than
that of boiling water, a bright yellowish green gas separates, which may
be received over mercury. Its smell is peculiar and aromatic. Water
absorbs at least seven times its volume of it. It destroys vegetable
blues. Its constituents are,

  1 volume chlorine  2·5   or 4·5
  2 volumes oxygen   2·222 or 4.

Thus this compound consists in weight of chlorine 4·5, oxygen 4 = 8·5.
It has been called _quarteroxide of chlorine_, but it is more probably a
_teroxide_. It has been supposed by some to possess acid properties, and
has therefore been called _chlorous acid_. But this is only as yet a
hypothesis.”

Surely this by the Doctor’s own showing is very slender authority for
renouncing our long-received doctrines concerning the constitution of
bleaching powder. I shall conclude by remarking that the ultra-atomists
are now in a dilemma about this substance; M. Welter, and many French
chemists calling it a sub-chloride, of 1 atom of chlorine to 2 atoms of
lime, and Dr. Thomson showing that Mr. Tennant, the greatest and best
manufacturer of it, has produced it in the state of a chloride, or 1
atom of each. The fact is, in chloride of lime, as in water of ammonia,
alcohol, and muriatic acid, there is no _sufficient reason_ for definite
proportion in any term short of saturation, and therefore we shall find
_that_ chloride in every gradation of strength from 1 per cent. of
chlorine up to 40 per cent.--the strongest which I succeeded in
preparing, though I passed a constant stream of chlorine in great excess
over a pure hydrate of lime for upwards of 24 hours, with frequent
renewal of the surface; indeed, till it refused to absorb any more gas,
as indicated by its remaining stationary in weight.


CHLOROMETRY; _Chlorometrie_, is the name given by the French to the
process for testing the decolouring power of any combination of
chlorine, but especially of the commercial articles, the chlorides of
lime, potash, and soda. M. Gay Lussac proposed many years ago the
following _graduated_ method of applying indigo to this purpose. As
indigo varies much in its dyeing quality, and of consequence in the
proportion of chlorine required for its decoloration, he assumes as the
unity of blanching power, one litre of chlorine gas, measured at the
mean pressure of 29·6 inches, and at the temperature of melting ice.
This volume of gas, when combined with a determinate quantity of water,
is employed to test the standard solution of indigo. For this purpose a
solution in sulphuric acid of any sample of indigo is taken, and diluted
with water to such a degree that 10 measures of it, in a graduated tube,
are decoloured by that one measure of combined chlorine gas. Each
measure of indigo solution so destroyed is called a degree, and this
measure being divided into five parts, the real test of chlorine is
given to fiftieths, which is sufficiently nice. For the standard of the
assays, a chloride of lime as pure and fully saturated as possible is
taken, and dissolved in such a quantity of water, that the solution
shall contain, or be equivalent to, one volume of chlorine gas.
Calculation proves that this condition is exactly fulfilled by
dissolving 4938 grammes of the said chloride in half a litre of water;
or in English measures, 5 gr. very nearly in 500 grain measures of
water. This solution, which serves for a type, indicates 10° in the
assay, or proof; that is to say, each single volume destroys the colour
of 10 volumes of the dilute indigo solution. It may be remarked, that a
greater degree of precision is in general attainable with a weak
solution of chlorine or a chloride, for example at 4° or 5°, than with
one much stronger; consequently if, after a preliminary trial, the
standard considerably exceeds 10°, a given volume of water must be added
to the solution, and then the above proof must be taken. If the volume
of water added was double, the number of degrees afterwards found must
be tripled, to obtain the true title of the chloride. It is, however, to
be observed that the degree of decoloration varies with the time taken
in making the mixture; the more slowly the chlorine is added to the
indigo, the less of it escapes into the atmosphere, and the more
effective it becomes in destroying the colour. The best mode of
obtaining comparable results, is to pour suddenly into the test quantity
of chlorine the whole volume of the indigo solution likely to be
decoloured; but it is requisite to find approximately beforehand, what
quantity of indigo-blue will probably be destroyed. When it comes to the
verge of destruction, it is green; but yellowish-brown when entirely
decomposed.

I have tried the indigo test in many ways, but never could confide in
it. The sulphuric solution of indigo is very liable to change by
keeping, and thus to lead to erroneous results. The method of testing
the chlorides by green sulphate of iron, described under bleaching, is
in my opinion preferable to the above.

M. Gay Lussac has recently proposed another proof of chlorine, founded
on the same principle as that by green vitriol, namely, the quantity of
it requisite to raise a metallic substance from a lower to a higher
stage of oxidizement. He now prescribes as the preferable plan of
chlorometry, to pour very slowly from a graduated glass tube, a
standard solution of the chloride, to be tested upon a determinate
quantity of arsenious acid dissolved in muriatic acid, till the whole
arsenious be converted into the arsenic acid. The value of the chloride
is greater the less of it is required to produce this effect. It is easy
to recognize, by a few drops of solution of indigo, the instant when all
the arsenious acid has disappeared; for then the blue tint is
immediately effaced, and cannot be restored by the addition of a fresh
drop of the indigo solution.

In graduating the arsenical chlorometer, M. Gay Lussac takes for his
unity the decolouring power of one volume of chlorine at 32° Fahr., and
divides it into 100 parts. Suppose that we prepare a solution of
chlorine containing its own volume of the gas, and an arsenious
solution, such, that under a like volume, the two solutions shall
reciprocally destroy each other. Let us call the first, the normal
solution of chlorine, and the second, the normal arsenious solution. We
shall fix at 10 grammes the weight of chloride of lime subjected to
trial; and dissolve it in water, so that the total volume of the
solution shall be a litre (1000 grammes measure), including the
sediment. If we take a constant volume of this solution, 10 centimetres
cube (10 gramme measures), for example, divided into 100 equal parts,
and pour into it gradually the arsenious solution (measured by like
portions), till the chlorine be destroyed, the bleaching power will be
proportional to the number of portions of the arsenious solution, which
the chloride shall have required. If the chloride has destroyed 100
portions of the arsenious solution, its title will be 100; if it has
destroyed 80 portions, its title will be 80, &c. and so forth.

On pouring the acidulous arsenious solution into the chloride of lime,
this will become very acid; the chlorine will be emitted abundantly, and
the proof will be quite incorrect. If, on the contrary, we pour the
solution of the chloride of lime into the arsenious solution, this evil
will not occur, since the chlorine will always find plenty of arsenious
acid to act upon, whatever be the dilution of the one or the other; but
in this case, the standard of the chlorine is not given directly, as it
is in the inverse ratio of the number of portions which are required to
destroy the measures of the arsenious solution. If 50 portions of the
chloride have been required, the proof will be 100 × 100/50 = 200°; if
200 have been required, the proof will be 100 × 100/200 = 50°, &c. This
evil is not, however, very serious, since we have merely to consult a
table, in which we can find the proof corresponding to each volume of
the chloride employed for destroying the constant measure of the
arsenious solution. The arsenious solution should be slightly tinged
with sulphate of indigo, so as to show, by the disappearance of the
colour, the precise point or instant of its saturation with chlorine,
that is, its conversion into arsenic acid. If the arsenious acid be
pure, the normal solution may be made directly by dissolving 4·439
grammes of it in muriatic acid (free from sulphurous acid), and diluting
the solution till it occupies one litre, or 1000 grammes measure.
_Annales de Chimie et Physique_, LX. 225.


CHOCOLATE. Is an alimentary preparation of very ancient use in Mexico,
from which country it was introduced into Europe by the Spaniards in the
year 1520, and by them long kept a secret from the rest of the world.
Linnæus was so fond of it, that he gave the specific name, _theobroma_,
food of the gods, to the cacao tree which produced it. The cacao-beans
lie in a fruit somewhat like a cucumber, about 5 inches long and 3-1/2
thick, which contains from 20 to 30 beans, arranged in 5 regular rows
with partitions between, and which are surrounded with a rose-coloured
spongy substance, like that of water-melons. There are fruits, however,
so large as to contain from 40 to 50 beans. Those grown in the West
India islands, Berbice and Demerara, are much smaller, and have only
from 6 to 15; their development being less perfect than in South
America. After the maturation of the fruit, when their green colour has
changed to a dark yellow, they are plucked, opened, their beans cleared
of the marrowy substance, and spread out to dry in the air. Like
almonds, they are covered with a thin skin or husk. In the West Indies
they are immediately packed up for the market when they are dried; but
in the Caraccas they are subjected to a species of slight fermentation,
by putting them into tubs or chests, covering them with boards or
stones, and turning them over every morning, to equalize the operation.
They emit a good deal of moisture, lose the natural bitterness and
acrimony of their taste by this process, as well as some of their
weight. Instead of wooden tubs, pits or trenches dug in the ground are
sometimes had recourse to for curing the beans; an operation called
_earthing_ (_terrer_). They are lastly exposed to the sun, and dried.
The latter kind are reckoned the best; being larger, rougher, of a
darker brown colour, and, when roasted, throw off their husk readily,
and split into several irregular fragments; they have an agreeable mild
bitterish taste, without acrimony. The Guiana and West India sorts are
smaller, flatter, smoother-skinned, lighter coloured, more sharp and
bitter to the taste. They answer best for the extraction of the butter
of cacao, but afford a less aromatic and agreeable chocolate. According
to Lampadius, the kernels of the West India cacao beans contain, in 100
parts, besides water, 53·1 of fat or oil, 16·7 of an albuminous brown
matter, which contains all the aroma of the bean, 10·91 of starch, 7-3/4
of gum or mucilage, 0·9 of lignine, and 2·01 of a reddish dye stuff
somewhat akin to the pigment of cochineal. The husks form 12 per cent.
of the weight of the beans; they contain no fat, but, besides lignine,
or woody fibre, which constitutes half their weight, they yield a light
brown mucilaginous extract by boiling in water. The fatty matter is of
the consistence of tallow, white, of a mild agreeable taste, called
butter of cacao, and not apt to turn rancid by keeping. It melts only at
122° Fahr., and should, therefore, make tolerable candles. It is soluble
in boiling alcohol, but precipitates in the cold. It is obtained by
exposing the beans to strong pressure in canvass bags, after they have
been steamed or soaked in boiling water for some time. From 5 to 6
ounces of butter may be thus obtained from a pound of cacao. It has a
reddish tinge when first expressed, but it becomes white by boiling with
water.

The beans, being freed from all spoiled and mouldy portions, are to be
gently roasted over a fire in an iron cylinder, with holes in its ends
for allowing the vapours to escape; the apparatus being similar to a
coffee-roaster. When the aroma begins to be well developed, the roasting
is known to be finished; and the beans must be turned out, cooled, and
freed by fanning and sifting from their husks. The kernels are then to
be converted into a paste, either by trituration in a mortar heated to
130° F., or by the following ingenious and powerful machine. The
chocolate paste has usually in France a little vanilla incorporated with
it, and a considerable quantity of sugar, which varies from one third of
its weight to equal parts. For a pound and a half of cacao, one pod of
vanilla is sufficient. Chocolate paste improves in its flavour by
keeping, and should therefore be made in large quantities at a time. But
the roasted beans soon lose their aroma, if exposed to the air.

[Illustration: 290]

_Fig._ 290. represents the chocolate mill. Upon the sole A, made of
marble, six conical rollers B B, are made to run by the revolution of
the upright axis or shaft _q_, driven by the agency of the fly wheel E
and bevel wheels I K. The sole A rests upon a strong iron plate, which
is heated by a small stove, introduced at the door H. The wooden frame
work F, forms a ledge, a few inches high, round the marble slab, to
confine the cocoa in the act of trituration. C is the hopper of the mill
through which the roasted beans are introduced to the action of the
rollers, passing first into the flat vessel D to be thence evenly
distributed. After the cacao has received the first trituration, the
paste is returned upon the slab, in order to be mixed with the proper
quantity of sugar, and vanilla, previously sliced and ground up with a
little hard sugar. When the chocolate is sufficiently worked, and while
it is thin with the heat and trituration, it must be put carefully into
the proper moulds. If introduced too warm, it will be apt to become damp
and dull on the surface; and, if too cold, it will not take the proper
form. It must be previously well kneaded with the hands to ensure the
expulsion of every air bubble.

In Barcelona, chocolate mills on this construction are very common, but
they are turned by a horse-gin set to work in the under story,
corresponding to H in the above figure. The shaft G is, in this case,
extended down through the marble slab, and is surrounded at its centre
with a hoop to prevent the paste coming into contact with it. Each of
these horse-mills turns out about ten pounds of fine chocolate in the
hour, from a slab two feet seven inches in diameter.

Chocolate is flavoured with cinnamon and cloves, in several countries,
instead of the more expensive vanilla. In roasting the beans the heat
should be at first very slow, to give time to the humidity to escape; a
quick fire hardens the surface, and injures the process. In putting the
paste into the tin plate, or other moulds, it must be well shaken down
to insure its filling up all the cavities, and giving the sharp and
polished impression so much admired by connoisseurs. Chocolate is
sometimes adulterated with starch; in which case it will form a pasty
consistenced mass when treated with boiling water. The harder the slab
upon which the beans are triturated, the better; and hence porphyry is
far preferable to marble. The grinding rollers of the mill should be
made of iron, and kept very clean.


CHROMATES, saline compounds of chromic acid with the bases. See
CHROMIUM.


CHROMIC ACID; see CHROMIUM.


CHROMIUM. The only ore of this metal, which occurs in sufficient
abundance for the purposes of art, is the octohedral chrome-ore,
commonly called chromate of iron, though it is rather a compound of the
oxides of chromium and iron. The fracture of this mineral is uneven; its
lustre imperfect metallic; its colour between iron-black and
brownish-black, and its streak brown. Its specific gravity, in the
purest state, rises to 4·5; but the usual chrome-ore found in the market
varies from 3 to 4. According to Klaproth, this ore consists of oxide of
chromium, 43; protoxide of iron, 34·7; alumina, 20·3; and silica, 2; but
Vauquelin’s analysis of another specimen gave as above, respectively,
55·5, 33, 6, and 2. It is infusible before the blowpipe; but it acts
upon the magnetic needle, after having been exposed to the reducing
smoky flame. It is entirely soluble in borax, at a high blowpipe heat,
and imparts to it a beautiful green colour.

Chrome-ore is found at the Bare Hills, near Baltimore, in Maryland; in
the Shetland isles, Unst and Fetlar; the department of Var, in France,
in small quantity; and near Portsoy, in Banffshire; as also in Silesia
and Bohemia.

The chief application of this ore is to the production of chromate of
potash, from which salt the various other preparations of this metal
used in the arts are obtained. The ore, freed, as well as possible, from
its gangue, is reduced to a fine powder, by being ground in a mill under
ponderous edge-wheels, and sifted. It is then mixed with one third or
one half its weight of coarsely bruised nitre, and exposed to a powerful
heat, for several hours, on a reverberatory hearth, where it is stirred
about occasionally. In the large manufactories of this country, the
ignition of the above mixture in pots is laid aside, as too operose and
expensive. The calcined matter is raked out, and lixiviated with water.
The bright yellow solution is then evaporated briskly, and the chromate
of potash falls down in the form of a granular salt, which is lifted out
from time to time from the bottom with a large ladle, perforated with
small holes, and thrown into a draining-box. This saline powder may be
formed into regular crystals of neutral chromate of potash, by solution
in water and slow evaporation; or it may be converted into a more
beautiful crystalline body, the bichromate of potash, by treating its
concentrated solution with nitric, muriatic, sulphuric, or acetic acid,
or, indeed, any acid exercising a stronger affinity for the second atom
of the potash than the chromic acid does.

Bichromate of potash, by evaporation of the above solution, and slow
cooling, may be obtained in the form of square tables, with bevelled
edges, or flat four-sided prisms. They are permanent in the air, have a
metallic and bitter taste, and dissolve in about one tenth of their
weight of water, at 60° F.; but in one half of their weight of boiling
water. They consist of chromic acid 13, potash 6; or, in 100 parts, 68·4
+ 31·6. This salt is much employed in calico-printing and in dyeing;
which see.

Chromate of lead, the chrome-yellow of the painter, is a rich pigment of
various shades, from deep orange to the palest canary yellow. It is made
by adding a limpid solution of the neutral chromate (the above granular
salt), to a solution, equally limpid, of acetate or nitrate of lead. A
precipitate falls, which must be well washed, and carefully dried out of
the reach of any sulphuretted vapours. A lighter shade of yellow is
obtained by mixing some solution of alum, or sulphuric acid, with the
chromate, before pouring it into the solution of lead; and an orange
tint is to be procured by the addition of subacetate of lead, in any
desired proportion.

For the production of chromate of potash from chrome ore, various other
processes have been recommended. The following formulæ, which have been
verified in practice, will prove useful to the manufacturers of this
important article:--

    I. Two parts of chrome ore, containing about 50 per cent. of
       protoxide of chromium:
       One part of saltpetre.
   II. Four parts of chrome ore, containing 34 per cent. of protoxide of
       chromium.
       Two parts of potashes.
       One part of saltpetre.
  III. Four parts of chrome ore,     --     34                   --
       Two of potashes.
       Four tenths of a part of peroxide of manganese.
   IV. Three parts of chrome ore.
       Four parts of saltpetre.
       Two parts of argal.

Some manufacturers have contrived to effect the conversion of the oxide
into an acid, and of course to form the chromate of potash, by the
agency of potash alone, in a calcining furnace, or in earthen pots fired
in a pottery kiln.

After lixiviating the calcined mixtures with water, if the solution be a
tolerably pure chromate of potash, its value may be inferred, from its
specific gravity, by the following table:--

  At specific gravity 1·28 it contains about 50 per cent. of the salt.
                      1·21                   33
                      1·18                   25
                      1·15                   20
                      1·12                   16
                      1·11                   14
                      1·10                   12

In making the red bichromate of potash from these solutions of the
yellow salt, nitric acid was at first chiefly used; but, in consequence
of its relatively high price, sulphuric, muriatic or acetic acid has
been frequently substituted upon the great scale.

There is another application of chrome which merits some notice here;
that of its green oxide to dyeing and painting on porcelain. This oxide
may be prepared by decomposing, with heat, the chromate of mercury, a
salt made by adding to nitrate of protoxide of mercury, chromate of
potash, in equivalent proportions. This chromate has a fine cinnabar
red, when pure; and, at a dull red heat, parts with a portion of its
oxygen and its mercurial oxide. From M. Dulong’s experiments it would
appear, that the purest chromate of mercury is not the best adapted for
preparing the oxide of chrome to be used in porcelain painting. He
thinks it ought to contain a little oxide of manganese and chromate of
potash, to afford a green colour of a fine tint, especially for pieces
that are to receive a powerful heat. Pure oxide of chrome preserves its
colour well enough in a muffle furnace; but, under a stronger fire, it
takes a dead-leaf colour.

The green oxide of chrome has come so extensively into use as an enamel
colour for porcelain, that a fuller account of the best modes of
manufacturing it must prove acceptable to many of my readers.

That oxide, in combination with water, called the hydrate, may be
economically prepared by boiling chromate of potash, dissolved in water,
with half its weight of flowers of sulphur, till the resulting green
precipitate ceases to increase, which may be easily ascertained by
filtering a little of the mixture. The addition of some potash
accelerates the operation. This consists in combining the sulphur with
the oxygen of the chromic acid, so as to form sulphuric acid, which
unites with the potash of the chromate into sulphate of potash, while
the chrome oxide becomes a hydrate. An extra quantity of potash
facilitates the deoxidizement of the chromic acid by the formation of
hyposulphite and sulphuret of potash, both of which have a strong
attraction for oxygen. For this purpose the clear lixivium of the
chromate of potash is sufficiently pure, though it should hold some
alumina and silica in solution, as it generally does. The hydrate may be
freed from particles of sulphur by heating dilute sulphuric acid upon
it, which dissolves it; after which it may be precipitated, in the state
of a carbonate, by carbonate of potash, not added in excess.

By calcining a mixture of bichromate of potash and sulphur in a
crucible, chromic acid is also decomposed, and a hydrated oxide may be
obtained; the sulphur being partly converted into sulphuret of
potassium, and partly into sulphuric acid (at the expense of the chromic
acid), which combines with the rest of the potash into a sulphate. By
careful lixiviation, these two new compounds may be washed away, and the
chrome green may be freed from the remaining sulphur, by a slight heat.

Liebig and Wöhler have lately contrived a process for producing a
subchromate of lead of a beautiful vermillion hue. Into saltpetre,
brought to fusion in a crucible at a gentle heat, pure chrome yellow is
to be thrown by small portions at a time. A strong ebullition takes
place at each addition, and the mass becomes black, and continues so
while it is hot. The chrome yellow is to be added till little of the
saltpetre remains undecomposed, care being taken not to overheat the
crucible, lest the colour of the mixture should become brown. Having
allowed it to settle for a few minutes, during which the dense basic
salt falls to the bottom, the fluid part, consisting of chromate of
potash and saltpetre, is to be poured off, and it can be employed again
in preparing chrome yellow. The mass remaining in the crucible is to be
washed with water, and the chrome red being separated from the other
matters, is to be dried after proper edulcoration. It is essential for
the beauty of the colour, that the saline solution should not stand long
over the red powder, because the colour is thus apt to become of a dull
orange hue. The fine crystalline powder subsides so quickly to the
bottom after every ablution, that the above precaution may be easily
observed.

As _Chromic Acid_ will probably ere long become an object of interest to
the calico printer, I shall describe here the best method of preparing
it. To 100 parts of yellow chromate of potash, add 136 of nitrate of
barytes, each in solution. A precipitate of the yellow chromate of
barytes falls, which being washed and dried would amount to 130 parts.
But while still moist it is to be dissolved in water by the intervention
of a little nitric acid, and then decomposed by the addition of the
requisite quantity of sulphuric acid, whereby the barytes is separated,
and the chromic acid remains associated with the nitric acid, from which
it can be freed by evaporation to dryness. On re-dissolving the chromic
acid residuum in water, filtering and evaporating to a proper degree, 50
parts of chromic acid may be obtained in crystals.

This acid may also be obtained from chromate of lime, formed by mixing
chromate of potash and muriate of lime; washing the insoluble chromate
of lime which precipitates, and decomposing it by the equivalent
quantity of oxalic acid, or for ordinary purposes even sulphuric acid
may be employed.

Chromic acid is obtained in quadrangular crystals, of a deep red colour;
it has a very acrid and styptic taste. It reddens powerfully litmus
paper. It is deliquescent in the air. When heated to redness, it emits
oxygen and passes into the deutoxide. When a little of it is fused along
with vitreous borax, the compound assumes an emerald green colour.

As chromic acid parts with its last dose of oxygen very easily, it is
capable in certain styles of calico printing of becoming a valuable
substitute for chlorine where this more powerful substance would not
from peculiar circumstances be admissible. For this ingenious
application, the arts are indebted to that truly scientific
manufacturer, M. Daniel Kœchlin, of Mulhouse. He discovered that
whenever chromate of potash has its acid set free by its being mixed
with tartaric or oxalic acid, or a neutral vegetable substance, (starch
or sugar for example), and a mineral acid, a very lively action is
produced, with disengagement of heat, and of several gases. The result
of this decomposition is the active reagent, chromic acid, possessing
valuable properties to the printer. Watery solutions of chromate of
potash and tartaric acid being mixed, an effervescence is produced which
has the power of destroying vegetable colours. But this power lasts no
longer than the effervescence. The mineral acids react upon the chromate
of potash only when vegetable colouring matter, gum, starch, or a
vegetable acid are present, to determine the disengagement of gas.
During this curious change carbonic acid is evolved; and when it takes
place in a retort, there is condensed in the receiver a colourless
liquid, slightly acid, exhaling somewhat of the smell of vinegar, and
containing a little empyreumatic oil. This liquid heated with the
nitrates of mercury or silver reduces these metals. On these principles
M. Kœchlin discharged indigo blue by passing the cloth through a
solution of chromate of potash, and printing nitric acid thickened with
gum upon certain spots. It is probable that the employment of chromic
acid would supersede the necessity of having recourse in many cases to
the more corrosive chlorine.

The following directions have been given for the preparation of a _blue
oxide_ of chrome. The concentrated alkaline solution of chromate of
potash is to be saturated with weak sulphuric acid, and then to every 8
lbs. is to be added 1 lb. of common salt, and half-a-pound of
concentrated sulphuric acid; the liquid will now acquire a green colour.
To be certain that the yellow colour is totally destroyed, a small
quantity of the liquor is to have potash added to it, and filtered; if
the fluid is still yellow, a fresh portion of salt and of sulphuric acid
is to be added: the fluid is then to be evaporated to dryness,
redissolved, and filtered; the oxide of chrome is finally to be
precipitated by caustic potash. It will be of a greenish-blue colour,
and being washed, must be collected upon a filter.

_Chromate of Potash, adulteration of, to detect._ The chromate of potash
has the power of combining with other salts up to a certain extent
without any very sensible change in its form and appearance; and hence
it has been sent into the market falsified by very considerable
quantities of sulphate and muriate of potash, the presence of which has
often escaped observation, to the great loss of the dyers who use it so
extensively. The following test process has been devised by M. Zuber, of
Mulhouse. Add a large excess of tartaric acid to the chromate in
question, which will decompose it, and produce in a few minutes a deep
amethyst colour. The supernatant liquor will, if the chromate be pure,
afford now no precipitate with the nitrates of barytes or silver; whence
the absence of the sulphates and muriates may be inferred. We must,
however, use dilute solutions of the chromate and acid, lest bitartrate
of potash be precipitated, which will take place if less than 60 parts
of water be employed. Nor must we test the liquid till the
decomposition be complete, and till the colour verge rather towards the
green than the yellow. Eight parts of tartaric acid should be added to
one of chromate to obtain a sure and rapid result. If nitrate of potash
(saltpetre) is the adulterating ingredient, it may be detected by
throwing it on burning coals, when deflagration will ensue. The green
colour is a certain mark of the transformation of the chromic acid
partially into the chrome oxide; which is effected equally by the
sulphurous acid and sulphuretted hydrogen. Here this metallic acid is
disoxygenated by the tartaric, as has been long known. The tests which I
should prefer, are the nitrates of silver and baryta, having previously
added so much nitric acid to the solution of the suspected chromate, as
to prevent the precipitation of the chromate of silver or baryta. The
smallest adulteration by sulphates or muriates will thus be detected.


CINNABAR; the native red sulphuret of mercury. It occurs sometimes
crystallized in rhomboids; has a specific gravity varying from 6·7 to
8·2; a flat conchoidal fracture; is fine grained; opaque; has an
adamantine lustre, and a colour passing from cochineal to ruby red. The
fibrous and earthy cinnabar has a scarlet hue. It is met with
disseminated in smaller or larger lumps in veins, which are surrounded
by a black clay, and is associated with native quicksilver, amalgam with
iron-ore, lead-glance, blende, copper-ore, gold, &c. Its principal
localities are Almaden in Spain, Idria in the Schiefergebirge, Kremnitz
and Schemnitz in Hungary; in Saxony, Bavaria, Bohemia, Nassau, China,
Japan, Mexico, Columbia, Peru. It consists of two primes of sulphur, =
32·240, combined with one of mercury, = 202,863; or in 100 parts of 12·7
sulphur + 87·3 mercury. It is the most prolific ore of this metal; and
is easily smelted by exposing a mixture of it with iron or lime to a red
heat in retorts. Factitious cinnabar is called in commerce VERMILLION,
which see, as also MERCURY.


CINNAMON. (_Cannelle_, Fr.; _Zimmt_, Germ.) Is the inner bark of the
_laurus cinnamomum_, a handsome-looking tree, which grows naturally to
the height of 18 or 20 feet, in Java, Sumatra, Ceylon, and other islands
in the East Indian seas. It has been transplanted to the Antilles,
particularly Guadaloupe and Martinique, as well as Cayenne, but there it
produces a bark of very inferior value to the Oriental.

Cinnamon is gathered twice a year, but not till after the tree has
attained to a certain age and maturity. The young twigs yield a bark of
better quality than the larger branches. The first and chief harvest
takes place from April to August; the second, from November to January.
After having selected the proper trees, all the branches more than three
years old are cut off; the epidermis is first removed with a two-edged
pruning knife, then a longitudinal incision is made through the whole
extent of the bark, and lastly, with the bluntest part of the knife, the
true bark is carefully stripped off in one piece. All these pieces of
bark are collected, the smaller ones are laid within the larger, and in
this state they are exposed to the sun, whereby in the progress of
drying, they become rolled into the shape of a quill. These convoluted
pieces are formed into oblong bundles of 20 or 30 lbs. weight, which are
placed in warehouses, sorted and covered with mats. Good cinnamon should
be as thin as paper, have its peculiar aromatic taste, without burning
the tongue, and leave a sweetish flavour in the mouth. The broken bits
of cinnamon are used in Ceylon for procuring the essential oil by
distillation. 445,367 lbs. of cinnamon were imported into this kingdom
in 1835, of which 16,604 only were retained for internal consumption.


CITRIC ACID. (_Acide citrique_, Fr.; _Citronensäure_, Germ.) Scheele
first procured this acid in its pure state from lemon juice, by the
following process. The juice put into a large tub, is to be saturated
with dry chalk in fine powder, noting carefully the quantity employed.
The citrate of lime which precipitates being freed from the supernatant
foul liquor, is to be well washed with repeated affusion and decantation
of water. For every 10 pounds of chalk employed, nine and a half pounds
of sulphuric acid, diluted with six times its weight of water, are to be
poured while warm upon the citrate of lime, and well mixed with it. At
the end of twelve hours, or even sooner, the citrate will be all
decomposed, dilute citric acid will float above, and sulphate of lime
will be found at the bottom. The acid being drawn off, the calcareous
sulphate must be thrown on a canvass filter, drained, and then washed
with water to abstract the whole acid.

The citric acid thus obtained may be evaporated in leaden pans, over a
naked fire till it acquires the specific gravity 1·13; after which it
must be transferred into another vessel, evaporated by a steam or water
bath till it assumes a syrupy aspect, when a pellicle appears first in
patches, and then over the whole surface. This point must be watched
with great circumspection, for if it be passed, the whole acid runs a
risk of being spoiled by carbonization. The steam or hot water must be
instantly withdrawn, and the concentrated acid put into a crystallizing
vessel in a dry, but not very cold apartment. At the end of four days,
the crystallization will be complete. The crystals must be drained,
re-dissolved in a small portion of water, the solution set aside to
settle its impurities, then decanted, re-evaporated, and
re-crystallized. A third or fourth crystallization may be necessary to
obtain a colourless acid.

If any citrate of lime be left undecomposed by the sulphuric acid, it
will dissolve in the citric acid, and obstruct its crystallization, and
hence it will be safer to use the slightest excess of sulphuric acid,
than to leave any citrate undecomposed. There should not however be any
great excess of sulphuric acid. If there be, it is easily detected by
nitrate of barytes, but not by the acetate of lead as prescribed by some
chemical authors; because the citrate of lead is not very soluble in the
nitric acid, and might thus be confounded with the sulphate, whereas
citrate of barytes is perfectly soluble in that test acid. Sometimes a
little nitric acid is added with advantage to the solution of the
coloured crystals, with the effect of whitening them.

Twenty gallons of good lemon juice will afford fully ten pounds of white
crystals of citric acid.

Attempts were made both in the West Indies and Sicily, to convert the
lime and lemon juice into citrate of lime, but they seem to have failed
through the difficulty of drying the citrate for shipment.

The crystals of citric acid are oblique prisms with four faces,
terminated by dihedral summits, inclined at acute angles. Their specific
gravity is 1·617. They are unalterable in the air. When heated, they
melt in their water of crystallization; and at a higher heat, they are
decomposed. They contain 18 per cent. of water, of which one half may be
separated in a dry atmosphere, at about 100° F., when the crystals fall
into a white powder.

Citric acid in crystals is composed by my analysis of carbon, 35·8,
oxygen 59·7, and hydrogen 45; results which differ very little from
those of Dr. Prout, subsequently obtained. I found its atomic weight to
be 8·375, compared to oxygen 1,000. I cannot account for Berzelius’s
statements relative to the composition of this acid.

Citric acid in somewhat crude crystals is employed with much advantage
in calico-printing. If adulterated with tartaric acid, the fraud may be
detected by adding potash to the solution of the acid, which will
occasion a precipitate of cream of tartar.


CIVET. (_Civette_, Fr.; _Zibeth_, Germ.) This substance approaches in
smell to musk and ambergris; it has a pale yellow colour, a somewhat
acrid taste, a consistence like that of honey, and a very strong
aromatic odour. It is the product of two small quadrupeds of the genus
_viverra_ (_v. zibetha_ and _v. civetta_), of which the one inhabits
Africa, the other Asia. They are reared with tenderness, especially in
Abyssinia. The civet is contained in a sac, situated between the anus
and the parts of generation, in either sex. The animal frees itself from
an excess of this secretion by a contractile movement which it exercises
upon the sac, when the civet issues in a vermicular form, and is
carefully collected. The negroes are accustomed to increase the
secretion by irritating the animal; and likewise introduce a little
butter, or other grease, by the natural slit in the bag, which mixes
with the odoriferous substance, and increases its weight. It is employed
only in perfumery.

According to M. Boutron-Chalard, it contains a volatile oil, to which it
owes its smell, some free ammonia, resin, fat, an extractiform matter,
and mucus. It affords, by calcination, an ash, in which there are some
carbonate and sulphate of potash, phosphate of lime, and oxide of iron.


CLAY (_Argile_, Fr.; _Thon_, Germ.) is a mixture of the two simple
earths, alumina and silica, generally tinged with iron. Lime, magnesia,
with some other colouring metallic oxides, are occasionally present in
small quantities in certain natural clays.

The different varieties of clay possess the following common
characters:--

1. They are readily diffusible through water, and are capable of forming
with it a plastic ductile mass, which may be kneaded by hand into any
shape. This plasticity exists, however, in very different degrees in the
different clays.

2. They concrete into a hard mass upon being dried, and assume, upon
exposure to the heat of ignition, a degree of hardness sometimes so
great as to give sparks by collision with hardened steel. In this state
they are no longer plastic with water, even when pulverised. Tolerably
pure clays, though infusible in the furnace, become readily so by the
admixture of lime, iron, manganese, &c.

3. All clays, even when previously freed from moisture, shrink in the
fire in virtue of the reciprocal affinity of their particles; they are
very absorbent of water in their dry state, and adhere strongly to the
tongue.

4. Ochrey, impure clays emit a disagreeable earthy smell when breathed
upon.

Brongniart distributes the clays into:--

1. Fire-clays, (_argiles apyres_, Fr.; _feuerfeste_, Germ.)

2. Fusible, (_schmelzbare_, Germ.)

3. Effervescing (_brausende_, Germ.), from the presence of chalk.

4. Ochrey (_ocreuses_, Fr.; _ockrige_, Germ.)

Fire-clay is found in the greatest abundance and perfection for
manufacturing purposes in,

1. _Slate-clay._ (_Thon-schiefer_, Germ.) Its colour is gray or
grayish-yellow. Massive, dull, or glimmering from admixture of
particles of mica. Fracture slaty, approaching sometimes to earthy.
Fragments tabular. Soft, sectile, and easily broken. Sp. gr. = 2·6.
Adheres to the tongue, and breaks down in water. It occurs along with
_pit coal_; which see. Slate-clay is ground, and reduced into a paste
with water, for making fire-bricks; for which purpose it should be as
free as possible from lime and iron.

2. _Common clay or loam._--This is an impure coarse pottery clay, mixed
with iron ochre, and occasionally with mica. It has many of the external
characters of plastic clay. It is soft to the touch, and forms, with
water, a somewhat tenacious paste; but is in general less compact, more
friable, than the plastic clays, which are more readily diffusible in
water. It does not possess the property of acquiring in water that
commencement of translucency which the purer clays exhibit. Although
soft to the touch, the common clay wants unctuosity, properly so called.
The best example of this argillaceous substance is afforded in the
London clay formation, which consists chiefly of bluish or blackish
clay, mostly very tough. Those of its strata which effervesce with acids
partake of the nature of marl. This clay is fusible at a strong heat, in
consequence of the iron and lime which it contains. It is employed in
the manufacture of bricks, tiles, and coarse pottery ware.

3. _Potter’s clay, or Plastic clay._--This species is compact, soft, or
even unctuous to the touch, and polishes with the pressure of the
finger; it forms, with water, a tenacious, very ductile, and somewhat
translucent paste. It is infusible in a porcelain kiln, but assumes in
it a great degree of hardness. Werner calls it _pipe-clay_. Good plastic
clay remains white, or if gray before, becomes white in the porcelain
kiln.

The geological position of the plastic clay is beneath the London clay,
and above the sand which covers the chalk formation. The plastic clay of
the Paris basin is described as consisting of two beds separated by a
bed of sand. The lower bed is the proper plastic clay. The plastic clay
of _Abondant_, near the forest of Dreux, analysed by Vauquelin, gave--

Silica, 43·5; alumina, 33·2; lime, 0·35; iron, 1; water, 18.

This clay is employed as a fire clay for making the bungs or _seggars_,
or coarse earthenware cases, in which china ware is fired.

The plastic clay of Dorsetshire and Devonshire supplies the great
Staffordshire potteries. It is gray coloured, less unctuous than that of
Dreux, and consequently more friable. It becomes white in the pottery
kiln, and is infusible at that heat. It causes no effervescence with
nitric acid, but falls down quickly in it, and becomes higher coloured.
Its refractoriness allows of a harder glaze being applied to the ware
formed from it without risk of the heat requisite for making the glaze
flow, affecting the biscuit either in shape or colour. “Most of the
plastic clays of France,” says M. Brongniart, “employed for the same
ware, have the disadvantage of reddening a little in a somewhat strong
heat; and hence it becomes necessary to coat them with a soft glaze,
fusible by means of excess of lead at a low heat, in order to preserve
the white appearance of the biscuit. Such a glaze has a dull aspect, and
cracks readily into innumerable fissures by alternations of hot and cold
water.” Hence one reason of the vast inferiority of the French
stone-ware to the English.

4. _Porcelain clay or Kaolin earth._--The Kaolins possess very
characteristic properties. They are friable in the hand, meagre to the
touch, and difficultly form a paste with water. When freed from the
coarse and evidently foreign particles interspersed through them, they
are absolutely infusible in the porcelain kiln, and retain their white
colour unaltered. They harden with heat like other clays, and perhaps in
a greater degree; but they do not acquire an equal condensation or
solidity, at least when they are perfectly pure. The Kaolins in general
appear to consist of alumina and silica in nearly equal proportions.
Most of the Kaolin clays contain some spangles of mica which betray
their origin from disintegrated granite.

This origin may be regarded as one of their most distinctive features.
Almost all the porcelain clays are evidently derived from the
decomposition of the felspars, granites, and principally those rocks of
felspar and quartz, called graphic granite. Hence, they are to be found
only in primitive mountain districts, among banks or blocks of granite,
forming thin seams or partings between them. In the same partings,
quartz and mica occur, being relics of the granite; while some seams of
Kaolin retain the external form of felspar.

The most valuable Kaolins have been found:--

In China and Japan. The specimens imported from these countries appear
pretty white; but are more unctuous to the touch, and more micaceous
than the porcelain clays of France.

In Saxony. The Kaolin employed in the porcelain manufactories of that
country has a slight yellow or flesh colour, which disappears in the
kiln, proving as Wallerius observed, that this tint is not owing to any
metallic matter.

In France, at Saint-Yriex-la-Perche, about 10 leagues from Limoges. The
Kaolin occurs there in a bed, or perhaps a vein of beds of granite, or
rather of that felspar rock called Pe-tun-tse, which exists here in
every stage of decomposition. This Kaolin is generally white, but
sometimes a little yellowish with hardly any mica. It is meagre to the
touch, and some beds include large grains of quartz, called pebbly by
the China manufacturers. This variety, when ground, affords, without the
addition of any fusible ingredient, a very transparent porcelain.

Near Bayonne. A Kaolin possessing the lamellated structure of felspar,
in many places. The rock containing it is a graphic granite in every
stage of decomposition.

In England, in the county of Cornwall. This Kaolin or China clay is very
white, and more unctuous to the touch than those upon the continent of
Europe mentioned above. Like them it results from the decomposition of
the felspars and granites, occurring in the middle of these rocks. Mr.
Wedgewood found it to contain 60 of alumina or pure clay, and 40 of
silica, in 100 parts.

Pure clay, the alumina of the chemist, is absolutely infusible; but when
subjected to the fire of a porcelain kiln, it contracts into about one
half of its total bulk. It must, however, be heated very cautiously,
otherwise it will decrepitate and fly in pieces, owing to the sudden
expansion into steam of the water combined with its particles, which is
retained with a considerable attractive force. It possesses little
plasticity, and consequently affords a very short paste, which is apt to
crack when kneaded into a cake.

It is not only infusible by itself, but it will not dissolve in the
fusible glasses; making them merely opaque. If either lime or silica be
added separately to pure clay, in any proportion, the mixture will not
melt in the most violent furnace; but if alumina, lime, and silica be
mixed together, the whole melts, and the more readily, the nearer the
mixture approaches to the following proportions:--1 of alumina, 1 of
lime, and 3 of sand. If the sand be increased to five parts, the
compound becomes infusible. These interesting facts show the reciprocal
action of those earths which are mixed most commonly in nature with
alumina.

Iron in small quantity, but in a state not precisely determined, though
probably of protoxide, does not colour the clays till they are subjected
to a powerful heat. There are very white clays, such as those of
Montereau, which do not become red till calcined in the porcelain kiln;
the oxide of iron contained in them, which colours them in that case,
was previously imperceptible. It appears from this circumstance, that
the clays fit for making fine white stone ware, as also the Kaolins
adapted to the manufacture of porcelain, are very rare.

Iron, in larger proportion, usually colours the clays green or
slate-blue, before they have been heated. Such clays, exposed to the
action of fire, become yellow or red according to the quantity of iron
which they contain. When the iron is very abundant, it renders the clays
fusible; but a little lime and silica must also be present for this
effect. The earthenware made with these ferruginous clays, can bear but
a moderate baking heat; it is thick, porous, and possesses the advantage
merely of cheapness, and of bearing considerable alternations of
temperature without breaking.

Alumina and the very aluminous natural clays which possess most
plasticity, are apt to crack in drying, or to lose their shape. This
very serious defect for the purposes of pottery is rectified, in some
measure, by adding to that earth a certain quantity of sand or silica.
Thus, a compound is formed which possesses less attraction for water,
and dries more equably from the openness of its body. The principal
causes of the distortion of earthenware vessels, are the unequal
thickness of their parts, and quicker desiccation upon one side than
another. Hard burnt stone-ware ground to powder, and incorporated with
clay, answers still better than sand for counteracting the great and
irregular contraction which natural pottery paste is apt to experience.
Such ground biscuit is called _cement_; and its grains interspersed
through the ware, may be regarded as so many solutions of continuity,
which arrest the fissures.

The preceding observations point out the principles of those arts which
employ clay for moulding by the wheel, and baking in a kiln. See
PORCELAIN and POTTERY.


CLOTH, MANUFACTURE OF. See TEXTILE FABRICS, WEAVING, WOOL.


CLOTH-BINDING. Nothing places in so striking a point of view the
superior taste, judgment, and resources of London tradesmen over those
of the rest of the world, than the extensive substitution which they
have recently made of embossed silks and calicoes for leather in the
binding of books. In old libraries, cloth-covered boards indeed may
occasionally be seen, but they have the meanest aspect, and are no more
to be compared with our modern cloth-binding, than the _jupon_ of a
trull, with the ballet dress of Taglioni. The silk or calico may be dyed
of any shade which use or fancy may require, impressed with gold or
silver foil in every form, and variegated by ornaments in relief, copied
from the most beautiful productions in nature. This new style of binding
is distinguished not more for its durability, elegance, and variety,
than for the economy and dispatch with which it ushers the offspring of
intellect into the world. For example, should a house eminent in this
line, such as that of Westleys, Friar-street, Doctors’-commons, receive
5000 volumes from Messrs. Longman & Co. upon Monday morning, they can
have them all ready for publication, within the incredibly short period
of two days; being far sooner than they could have rudely boarded them
upon the former plan. The reduction of price is not the least advantage
incident to the new method, amounting to fully 50 per cent. upon that
with leather.

The dyed cloth being cut by a pattern to the size suited to the volume,
is passed rapidly through a roller press, between engraved cylinders of
hard steel, whereby it receives at once the impress characteristic of
the back, and the sides, along with embossed designs over the surface in
sharp relief. The cover thus rapidly fashioned, is as rapidly applied by
paste to the stitched and pressed volume; no time being lost in mutual
adjustments; since the steel rollers turn off the former, of a shape
precisely adapted to the latter. Hard glazed and varnished calico is
moreover much less an object of depredation to moths, and other insects,
than ordinary leather has been found to be.


COBALT. This metal being difficult to reduce from its ores, is therefore
very little known, and has not hitherto been employed in its simple
state in any of the arts; but its oxide has been extensively used on
account of the rich blue colour which it imparts to glass, and the glaze
of porcelain and stone-ware. The principal ores of cobalt are those
designated by mineralogists under the names of _arsenical cobalt_ and
_gray cobalt_. The first contains, in addition to cobalt, some arsenic,
iron, nickel, and occasionally silver, &c. The other is a compound of
cobalt with iron, arsenic, sulphur, and nickel. Among the gray cobalts,
the ore most esteemed for its purity is that of Tunaberg in Sweden. It
is often in regular crystals which possess the lustre and colour of
polished steel. The specific gravity of cobalt pyrites is 6·36 to 4·66.
The Tunaberg variety afforded to Klaproth, cobalt, 44; arsenic, 55·5;
sulphur, 0·5: so that it is an arseniuret. Others, however, contain much
sulphur as well as iron. It imparts at the blowpipe a blue colour to
borax and other fluxes, and gives out arsenical fumes.

The ore being picked to separate its concomitant stony matters, is
pounded fine and passed through a sieve; and is also occasionally
washed. The powder is then spread on the sole of a reverberatory
furnace, the flue of which leads into a long horizontal chimney. Here it
is exposed to calcination for several hours, to expel the sulphur and
arsenic that may be present; the former burning away in sulphurous acid
gas, the latter being condensed into the white oxide or arsenious acid,
whence chiefly the market is supplied with this article. This calcining
process can never disengage the whole of these volatile ingredients, and
there is therefore a point beyond which it is useless to push it; but
the small quantities that remain are not injurious to the subsequent
operations. The roasted ore is sifted anew; reduced to a very fine
powder, and then mixed with 2 or 3 parts of very pure siliceous sand, to
be converted into what is called _zaffre_. With this product glasses are
generally coloured blue, as well as enamels and pottery glaze. In the
works where cobalt ores are treated, a blue glass is prepared with the
zaffre, which is well known under the name of smalt or azure blue. This
azure is made by adding to the zaffre 2 or 3 parts of potash, according
to its richness in cobalt, and melting the mixture in earthen crucibles.
The fused mass is thrown out while hot into water; and is afterwards
triturated and levigated in mills mounted for the purpose. There remains
at the bottom of the earthen pot a metallic lump, which contains a
little cobalt, much nickel, arsenic, iron, &c. This is called _speiss_.

As it is the _oxide_ of cobalt which has the colouring quality, the
calcination serves the purpose of oxidizement, as well as of expelling
the foreign matters.

A finer cobalt-oxide is procured for painting upon hard porcelain, by
boiling the cobalt ore in nitric acid, which converts the arsenic into
an acid, and combines it with the different metals present in the
mineral. These arseniates being unequally soluble in nitric acid, may be
separated in succession by a cautious addition of carbonate of soda or
potash; and the arseniate of cobalt as the most soluble remains
unaffected. It has a rose colour; and is easily distinguishable, whence
the precipitation may be stopped at the proper point. The above solution
should be much diluted, and the alkali should be cautiously added with
frequent agitation.

[Illustration: 291 292]

The cobalt ores, rich in nickel, are exposed to slow oxidizement in the
air, whereby the iron, cobalt, arsenic, and sulphur get oxygenated by
the atmospheric moisture, but the nickel continues in the metallic
state. This action of the weather must not be extended beyond a year,
otherwise the nickel becomes affected, and injures the cobalt blue. The
ore hereby increases in weight, from 8 to 10 per cent. _Fig._ 291. is a
longitudinal section of the furnace: _fig._ 292., a horizontal section
upon a level with the sole of the hearth. It is constructed for wood
fuel, and the hearth is composed of fire-bricks or tiles. The vapours
and gases disengaged in the roasting, pass off through the flues _a a_,
into the channels _b b_, and thence by _c_ into the common vent, or
poison chamber. See the representation of the poison tower of Altenberg,
under the article ARSENIC. The flues are cleared out by means of
openings left at suitable situations in the brick-work of the chimneys.

The azure manufacture is carried on chiefly in winter, in order that the
external cold may favour the more complete condensation of the acids of
arsenic. From 3 to 5 cwt. of Schlich (pasty ore), are roasted at one
operation, and its bed is laid from 5 to 6 inches thick. After two
hours, it must be turned over; and the stirring must be repeated every
half hour, till no more arsenic is observed to exhale. The process being
then finished, the ore must be raked out of the furnace, and another
charge introduced.

The duration of the roasting is regulated partly by the proportion of
sulphur and arsenic present, and partly by the amount of nickel; which
must not be suffered to become oxidized, lest it should spoil the colour
of the smalt. The latter ores should be but slightly roasted, so as to
convert the nickel into _speiss_. The roasted ore must be sifted in a
safety apparatus. The loss of weight in the roasting amounts, upon the
average, to 36 per cent. The roasted ore has a brownish gray hue, and is
called _safflor_ in German, and is distributed into different sorts. F F
S is the finest _safre_; F S, fine; O S, ordinary; and M S, middling.
These varieties proceed from various mixtures of the calcined ores. The
roasted ore is ground up along with sand, elatriated, and, when dry, is
called _zaffre_. It is then mixed with a sufficient quantity of potash
for converting the mixture into a glass.

[Illustration: 293 294]

_Figs._ 293. and 294. represent a round smalt furnace, in two vertical
sections, at right angles to each other. The fire-place is vaulted or
arched; the flame orifice _a_, is in the middle of the furnace; _b_ is
the feed hole; _c_, a tunnel which serves as an ash-pit, and to supply
air; _d_, openings through which the air arrives at the fuel, the wood
being placed upon the vault; _e_, knee holes for taking out the scoriæ
from the pot bottoms; _f_, working orifices, with cast-iron plates _g_,
in front of them. Under these are the additional outlets _h_. The smoke
and flame pass off through the orifices _i_, which terminate in expanded
flues, where the sand may be calcined or the wood may be baked. Eight
hours are sufficient for one vitrifying operation, during which the
glass is stirred about several times in the earthen melting pots.

The preparation of the different shades of blue glass are considered as
secrets in the smelting works; and marked with the following letters:--F
F F C, the finest; F C, fine; M C, middling; O C, ordinary. A melting
furnace, containing 8 pots of glass; produces in 24 hours, from 24 cwts.
of the mixture, 19 cwts. of blue glass; and from 1/2 to 3/4 cwt. of
scoriæ or speiss (_speise_). The composition _speise_, according to
Berthier, is,--nickel, 49·0; arsenic, 37·8; sulphur, 7·8; copper, 1·6;
cobalt, 3·2 in 100. Nickel, arsenic, and sulphur, are its essential
constituents; the rest are accidental, and often absent. The freer the
cobalt ore is from foreign metals, the finer is the colour, and the
deeper is the shade; paler tints are easily obtained by dilution with
more glass. The presence of nickel gives a violet tone.

The production of smalt in the Prussian states amounted, in 1830, to
7452-1/2 cwts.; and, in Saxony, to 9697 cwts.; in 1825, to 12,310 cwts.

One process for making fine smalt has been given under the title AZURE;
I shall introduce another somewhat different here.

The ore of cobalt is to be reduced to very fine powder, and then roasted
with much care. One part, by weight, is next to be introduced, in
successive small portions, into an iron vessel, in which three parts of
acid sulphate of potassa has been previously fused, at a moderate
temperature. The mixture, at first fluid, soon becomes thick and firm,
when the fire is to be increased, until the mass is in perfect fusion,
and all white vapours have ceased. It is then to be taken out of the
crucible with an iron ladle, the crucible is to be recharged with acid
sulphate of potash, and the operation continued as before, until the
vessel is useless. The fused mass contains sulphate of cobalt, neutral
sulphate of potassa, and arseniate of iron, with a little cobalt. It is
to be pulverized, and boiled in an iron vessel, with water, as long as
the powder continues rough to the touch. The white, or yellowish white
residue, may be allowed to separate from the solution, either by
deposition or filtration. Carbonate of potassa, free from silica, is
then to be added to the solution, and the carbonate of cobalt thrown
down is to be separated and well washed, if possible, with warm water;
the same water may be used to wash other portions of the fused mass. The
filtered liquid which first passes, is a saturated solution of sulphate
of potassa: being evaporated to dryness in an iron vessel, it may be
reconverted into acid sulphate by fusing it with one half its weight of
sulphuric acid: this salt is then as useful as at first.

The oxide of cobalt thus obtained, contains no nickel; so little oxide
of iron is present, that infusion of galls does not show its presence;
it may contain a little copper, if that metal exists in the ore, but it
is easily separated by the known methods. Sometimes sulphuretted
hydrogen will produce a yellow brown precipitate in the solution of the
fused mass; this, however, contains no arsenic, but is either sulphuret
of antimony or bismuth, or a mixture of both.

It has been found advantageous to add to the fused mass, sulphate of
iron, calcined to redness, and one tenth of nitre when the residue is
arseniate of iron, and contains no arseniate of cobalt. There is then no
occasion to act upon the residue a second time for the cobalt in it.

This process is founded on the circumstances that the sulphate of cobalt
is not decomposed by a red heat, and that the arseniates of iron and
cobalt are insoluble in all neutral liquids. It is quite evident that to
obtain a perfect result, the excess of acid in the bisulphate of potassa
must be completely driven off by the red heat applied.

110,646 lbs. of smalts were imported into the United Kingdom in 1835,
and 96,949 were retained for home consumption. In 1834, only 16,223 lbs.
were retained.

In 1835, 322,562 lbs. of zaffres were imported, and 336,824 are stated
to have been retained, which is obviously an error. 284,000 lbs. were
retained in 1834.


COCCULUS INDICUS, or Indian berry, is the fruit of the _Menispermum
Cocculus_, a large tree, which grows upon the coasts of Malabar, Ceylon,
&c. The fruit is blackish, and of the size of a large pea. It owes its
narcotic and poisonous qualities to the vegeto-alkaline chemical
principle called _picrotoxia_, of which it contains about one-fiftieth
part of its weight. It is sometimes thrown into waters to intoxicate or
kill fishes; and it is said to have been employed to increase the
inebriating qualities of ale or beer. Its use for this purpose is
prohibited by act of parliament, under a penalty of 200_l._ upon the
brewer, and 500_l._ upon the seller of the drug.


COCHINEAL was taken in Europe at first for a seed, but was proved by the
observations of Lewenhoeck to be an insect, being the female of that
species of shield-louse, or _coccus_, discovered in Mexico, so long ago
as 1518. It is brought to us from Mexico, where the animal lives upon
the _cactus opuntia_ or _nopal_. Two sorts of cochineal are
gathered--the wild, from the woods, called by the Spanish name _grana
silvestra_; and the cultivated, or the _grana fina_, termed also
_mesteque_, from the name of a Mexican province. The first is smaller,
and covered with a cottony down, which increases its bulk with a matter
useless in dyeing; it yields, therefore, in equal weight, much less
colour, and is of inferior price to that of the fine cochineal. But
these disadvantages are compensated in some measure to the growers by
its being reared more easily, and less expensively; partly by the
effect of its down, which enables it better to resist rains and storms.

The wild cochineal, when it is bred upon the field nopal, loses in part
the tenacity and quantity of its cotton, and acquires a size double of
what it has on the wild opuntias. It may therefore be hoped, that it
will be improved by persevering care in the rearing of it, when it will
approach more and more to fine cochineal.

The fine cochineal, when well dried and well preserved, should have a
gray colour, bordering on purple. The gray is owing to the powder, which
naturally covers it, and of which a little adheres; as also to a waxy
fat. The purple shade arises from the colour extracted by the water in
which they were killed. It is wrinkled with parallel furrows across its
back, which are intersected in the middle by a longitudinal one; hence,
when viewed by a magnifier, or even a sharp naked eye, especially after
being swollen by soaking for a little in water, it is easily
distinguished from the factitious, smooth, glistening, black grains, of
no value, called East India cochineal, with which it is often shamefully
adulterated by certain London merchants. The genuine cochineal has the
shape of an egg, bisected through its long axis, or of a tortoise, being
rounded like a shield upon the back, flat upon the belly, and without
wings.

These female insects are gathered off the leaves of the nopal plant,
after it has ripened its fruit, a few only being left for brood, and are
killed, either by a momentary immersion in boiling water, by drying upon
heated plates, or in ovens: the last become of an ash-gray colour,
constituting the _silver_ cochineal, or _jaspeada_; the second are
blackish, called _negra_, and are most esteemed, being probably driest;
the first are reddish brown, and reckoned inferior to the other two. The
dry cochineal being sifted, the dust, with the imperfect insects and
fragments which pass through, are sold under the name of _granillo_.

Cochineal keeps for a long time in a dry place. Hellot says that he has
tried some 130 years old, which produced the same effect as new
cochineal.

We are indebted to MM. Pelletier and Caventou for a chemical
investigation of cochineal, in which its colouring matter was skilfully
eliminated.

Purified sulphuric ether acquired by digestion with it a golden yellow
colour, amounting by Dr. John to one tenth of the weight of the insect.
This infusion left, on evaporation, a fatty wax of the same colour.

Cochineal, exhausted by ether, was treated with alcohol at 40° B. After
30 infusions in the digester of M. Chevreul, the cochineal continued to
retain colour, although the alcohol had ceased to have any effect on it.
The first alcoholic liquors were of a red verging on yellow. On cooling,
they let fall a granular matter. By spontaneous evaporation, this
matter, of a fine red colour, separated, assuming more of the
crystalline appearance. These species of crystals dissolved entirely in
water, which they tinged of a yellowish-red.

This matter has a very brilliant purple-red colour; it adheres strongly
to the sides of the vessels; it has a granular and somewhat crystalline
aspect, very different, however, from those compound crystals alluded to
above; it is not altered by the air, nor does it sensibly attract
moisture. Exposed to the action of heat, it melts at about the fiftieth
degree centigrade (122° Fahr.). At a higher temperature it swells up,
and is decomposed with the production of carburetted hydrogen, much oil,
and a small quantity of water, very slightly acidulous. No trace of
ammonia was found in these products.

The colouring principle of cochineal is very soluble in water. By
evaporation, the liquid assumes the appearance of syrup, but never
yields crystals. It requires of this matter a portion almost
imponderable to give a perceptible tinge of bright purplish red to a
large body of water. Alcohol dissolves this colouring substance, but, as
we have already stated, the more highly it is rectified the less of it
does it dissolve. Sulphuric ether does not dissolve the colouring
principle of cochineal; but weak acids do, possibly owing to their water
of dilution. No acid precipitates it in its pure state. This colouring
principle, however, appears to be precipitable by all the acids, when it
is accompanied by the animal matter of the cochineal.

The affinity of alumina for the colouring matter is very remarkable.
When that earth, newly precipitated, is put into a watery solution of
the colouring principle, this is immediately seized by the alumina. The
water becomes colourless, and a fine red lake is obtained, if we operate
at the temperature of the atmosphere; but if the liquor has been hot,
the colour passes to crimson, and the shade becomes more and more
violet, according to the elevation of the temperature, and the
continuance of the ebullition.

The salts of tin exercise upon the colouring matter of cochineal a
remarkable action. The muriatic protoxide of tin forms a very abundant
violet precipitate in the liquid. This precipitate verges on crimson, if
the salt contains an excess of acid. The muriatic deutoxide of tin
produces no precipitate, but changes the colour to scarlet-red. If
gelatinous alumina be now added, we obtain a fine red precipitate, which
does not pass to crimson by boiling.

To this colouring principle the name _carminium_ has been given, because
it forms the basis of the pigment called carmine.

The process followed in Germany for making carmine, which consists in
pouring a certain quantity of solution of alum into a decoction of
cochineal, is the most simple of all, and affords an explanation of the
formation of carmine, which is merely the carminium and the animal
matter precipitated by the excess of acid in the salt, which has taken
down with it a small quantity of alumina; though it appears that alumina
ought not to be regarded as essential to the formation of carmine. In
fact, by another process, called by the name of Madame Cenette of
Amsterdam, the carmine is thrown down, by pouring into the decoction of
cochineal a certain quantity of the binoxalate of potash. When carbonate
of soda is added, then carminated lake also falls down. That carmine is
a triple compound of animal matter, carminium, and an acid appears from
the circumstance, that liquors which have afforded their carmine, when a
somewhat strong acid is poured into them, yield a new formation of
carmine by the precipitation of the last portions of the animal matter.
But whenever the whole animal matter is thrown down, the decoctions,
although still much charged with the colouring principle, can afford no
more carmine. Such decoctions may be usefully employed to make
carminated lakes, saturating the acid with a slight excess of alkali,
and adding gelatinous alumina. The precipitates obtained, on adding
acids to the alkaline decoctions of cochineal, are therefore true
carmines, since they do not contain alumina; but the small quantity of
alumina which is thrown down by alum in the manufacture of carmine,
augments its bulk and weight. It gives, besides, a greater lustre to the
colour, even though diluting and weakening it a little.

The carmines found in the shops of Paris were analysed, and yielded the
same products. They are decomposed by the action of heat, with the
diffusion at first of a very strong smell of burning animal matter, and
then of sulphur. A white powder remained, amounting to about one-tenth
of the matter employed, and which was found to be alumina. Other
quantities of carmine were treated with a solution of caustic potash,
which completely dissolved them, with the exception of a beautiful red
powder, not acted on by potash and concentrated acids, and which was
recognized to be red sulphuret of mercury or vermillion. This matter,
evidently foreign to the carmine, appears to have been added, in order
to increase its weight.

The preceding observations and experiments seem calculated to throw some
light on the art of dyeing scarlet and crimson. The former is effected
by employing a cochineal bath, to which there have been added, in
determinate proportions, acidulous tartrate of potash, and
nitro-muriatic deutoxide of tin. The effect of these two salts is now
well known. The former, in consequence of its excess of acid, tends to
redden the colour, and to precipitate it along with the animal matter:
the latter acts in the same manner, at first by its excess of acid, then
by the oxide of tin which falls down also with the carmine and animal
matter, and is fixed on the wool, with which it has of itself a strong
tendency to combine. MM. Pelletier and Caventou remark, that “to obtain
a beautiful shade, the muriate of tin ought to be entirely at the
maximum of oxidizement; and it is in reality in this state that it must
exist in the solution of tin prepared according to the proportions
prescribed in M. Berthollet’s treatise on dyeing.”

We hence see why, in dyeing scarlet, the employment of alum is carefully
avoided, as this salt tends to convert the shade to a crimson. The
presence of an alkali would seem less to be feared. The alkali would
occasion, no doubt, a crimson-coloured bath; but it would be easy in
this case to restore the colour, by using a large quantity of tartar. We
should, therefore, procure the advantage of having a bath better charged
with colouring matter and animal substance. It is for experience on the
large scale to determine this point. As to the earthy salts, they must
be carefully avoided; and if the waters be selenitish, it would be a
reason for adding a little alkali.

To obtain crimson, it is sufficient, as we know, to add alum to the
cochineal bath, or to boil the scarlet cloth in alum water. It is also
proper to diminish the dose of the salt of tin, since it is found to
counteract the action of the alum.

The alkalies ought to be rejected as a means of changing scarlet to
crimson. In fact, crimsons by this process cannot be permanent colours,
as they pass into reds by the action of acids.

According to M. Von Grotthuss, carmine may be deprived of its golden
shade by ammonia, and subsequent treatment with acetic acid and alcohol.
Since this fact was made known, M. Herschel, colour maker at Halle, has
prepared a most beautiful carmine.

The officers of Her Majesty’s Customs have lately detected a system of
adulterating cochineal, which has been practised for many years upon a
prodigious scale by a mercantile house in London. I have analyzed about
100 samples of such cochineal, from which it appears that the genuine
article is moistened with gum-water, agitated in a box or leather bag,
first, with sulphate of baryta in fine powder, afterwards with bone or
ivory black, to give it the appearance of _negra_ cochineal, and then
dried. By this means about 12 per cent. of the worthless heavy spar is
sold at the price of cochineal, to the enrichment of the sophisticators,
and the disgrace and injury of British trade and manufactures.

The specific gravity of genuine cochineal is 1·25; that of the cochineal
loaded with the barytic sulphate 1·35. It was taken in oil of turpentine
and reduced to water as unity, because the waxy fat of the insects
prevents the intimate contact of the latter liquid with them, and the
ready expulsion of air from their wrinkled surface. They are not at all
acted upon by the oil, but are rapidly altered by water, especially when
they have been gummed and barytified.

The quantities of cochineal imported into the United Kingdom in the
following years, were:--

             Libs.
  1827.     320,722
  1828.     258,032
  1829.     288,456
  1830.     316,589
  1831.     244,371
  1832.     388,478
  1833.     359,381
  1834.     410,387
  1835.     418,320

The quantities re-exported were:--

             Libs.
  1827.     145,756
  1828.     158,109
  1829.     153,738
  1830.     100,059
  1831.     168,329
  1832.     138,270
  1833.     130,732
  1834.     265,490
  1835.     352,023

Humboldt states that so long ago as the year 1736, there was imported
into Europe from South America cochineal to the value of 15 millions of
francs. Its high price had for a long time induced dyers to look out for
cheaper substitutes in dyeing red, and since science has introduced so
many improvements in tinctorial processes, both madder and lac have been
made to supersede cochineal to a very great extent. Its price has, in
consequence of this substitution, as well as from more successful modes
of cultivation, fallen very greatly of late years. At present it is only
7_s._ per lib. in London. See SCARLET DYEING.


COCOA, STEARINE, AND ELAINE. Mr. Soames obtained a patent in September
1829, for making these useful articles, by the following process:

He takes the substance called cocoa-nut oil, in the state of lard, in
which it is imported into this country, and submits it to a strong
hydraulic pressure, having made it up in small packages, 3 or 4 inches
wide, 2 feet long, and 1 or 1-1/2 inches thick. These packages are
formed by first wrapping up the said substance in a strong linen cloth,
of close texture, and then in an outward wrapper of strong sail cloth.
The packages are to be placed side by side, in single rows, between the
plates of the press, allowing a small space between the packages for the
escape of the _elaine_.

The temperature at which the pressure is begun, should be from about 50
to 55 degrees, or in summer as nearly at this pitch as can be obtained,
and the packages of the said substance intended for pressure, should be
exposed for several hours previously to about the same temperature. When
the packages will no longer yield their oil or elaine freely at this
temperature, it is to be gradually raised; but it must at no time exceed
65 degrees, and the lower the temperature at which the separation can be
effected, the better will be the quality of the oil expressed.

When the packages are sufficiently pressed, that is, when they will give
out no more oil, or yield it only in drops at long intervals, the
residuum in them is to be taken out and cleansed and purified, which is
done by melting it in a well-tinned copper vessel, which is fixed in an
outer vessel, having a vacant space between, closed at the top, into
which steam is admitted, and the heat is kept up moderately for a
sufficient time to allow the impurities to subside; but if a still
higher degree of purity is required, it is necessary to pass it through
filters of thick flannel lined with blotting paper.

Having been thus cleansed or purified, it is fit for the manufacture of
candles, which are made by the ordinary process used in making mould
tallow candles. Having thus disposed of the stearine, or what is called
the first product, he proceeds with the elaine or oil expressed from it,
and which he calls the second product, as follows: that is to say, he
purifies it by an admixture, according to the degree of its apparent
foulness, of from 1 to 2 per cent. by weight of the sulphuric acid of
commerce, of about 1·80 specific gravity, diluted with six times its
weight of water. The whole is then to be violently agitated by
mechanical means, and he prefers for this purpose the use of a vessel
constructed on the principle of a common barrel churn. When sufficiently
agitated, it will have a dirty whitish appearance, and is then to be
drawn off into another vessel, in which it is to be allowed to settle,
and any scum that rises is to be carefully taken off. In a day or two
the impurities will be deposited at the bottom of the oil, which will
then become clear, or nearly so, and it is to be filtered through a
thick woollen cloth, after which it will be fit for burning in ordinary
lamps and for other uses.

The process of separating the elaine from the stearine, by pressure, in
manner aforesaid, had never before been applied to the substance called
cocoa-nut oil, and consequently no product had heretofore been obtained
thereby from that substance, fit for being manufactured into candles in
the ordinary way, or for being refined by any of the usual modes, so as
to burn in ordinary lamps, both which objects are obtained by this
method of preparing or manufacturing the said substance.

Candles well made from the above material are a very superior article.
The light produced is more brilliant than from the same sized candle
made of tallow; the flame is perfectly colourless, and the wick remains
free from cinder, or any degree of foulness during combustion.


COFFEE. The coffee is the seed of a tree of the family _rubiaceæ_, and
belongs to the Pentandria monogynia of Linnæus. There are several
species of the genus, but the only one cultivated is the _Coffæa
Arabica_, a native of Upper Ethiopia and Arabia Felix. It rises to the
height of 15 or 20 feet; its trunk sends forth opposite branches in
pairs above and at right angles to each other; the leaves resemble those
of the common laurel, although not so dry and thick. From the angle of
the leaf-stalks small groups of white flowers issue, which are like
those of the Spanish jasmine. These flowers fade very soon, and are
replaced by a kind of fruit not unlike a cherry, which contains a yellow
glairy fluid, enveloping two small seeds or berries convex upon one
side, flat and furrowed upon the other in the direction of the long
axis. These seeds are of a horny or cartilaginous nature; they are glued
together, each being surrounded with a peculiar coriaceous membrane.
They constitute the coffee of commerce.

It was not till towards the end of the 15th century that the coffee tree
began to be cultivated in Arabia. Historians usually ascribe the
discovery of the use of coffee as a beverage to the superior of a
monastery there, who, desirous of preventing the monks from sleeping at
their nocturnal services, made them drink the infusion of coffee upon
the report of shepherds, who pretended that their flocks were more
lively after browsing on the fruit of that plant. The use of coffee was
soon rapidly spread, but it encountered much opposition on the part of
the Turkish government, and became the occasion of public assemblies.
Under the reign of Amurath III. the mufti procured a law to shut all the
coffee-houses, and this act of suppression was renewed under the
minority of Mahomet IV. It was not till 1554 under Solyman the Great
that the drinking of coffee was accredited in Constantinople; and a
century elapsed before it was known in London and Paris. Solyman Aga
introduced its use into the latter city in 1669, and in 1672 an Armenian
established the first _café_ at the fair of Saint Germain.

When coffee became somewhat of a necessary of life from the influence of
habit among the people, all the European powers who had colonies between
the tropics, projected to form plantations of coffee trees in them. The
Dutch were the first who transported the coffee plant from Moka to
Batavia, and from Batavia to Amsterdam. In 1714 the magistrates of that
city sent a root to Louis XIV. which he caused to be planted in the
Jardin du Roi. This became the parent stock of all the French coffee
plantations in Martinique.

The most extensive culture of coffee is still in Arabia Felix, and
principally in the kingdom of Yemen, towards the cantons of Aden and
Moka. Although these countries are very hot in the plains, they possess
mountains where the air is mild. The coffee is generally grown halfway
up on their slopes. When cultivated on the lower grounds it is always
surrounded by large trees which shelter it from the torrid sun, and
prevent its fruit from withering before their maturity. The harvest is
gathered at three periods, the most considerable occurs in May, when the
reapers begin by spreading cloths under the trees, then shaking the
branches strongly, so as to make the fruit drop, which they collect, and
expose upon mats to dry. They then pass over the dried berries a very
heavy roller, to break the envelopes, which are afterwards winnowed away
with a fan. The interior bean is again dried before being laid up in
store.

In Demerara, Berbice, and some of our West India islands, where much
good coffee is now raised, a different mode of treating the pulpy fruit
and curing the beans is adopted. When the cherry-looking berry has
assumed a deep-red colour it is gathered, and immediately subjected to
the operations of a mill composed of two wooden rollers, furnished with
iron plates, which revolve near a third fixed roller called the _chops_.
The berries are fed into a hopper above the rollers, and falling down
between them and the chops, they are stripped of their outer skins and
pulp, while the twin beans are separated from each other. These beans
then fall upon a sieve, which allows the skin and the pulp to pass
through, while the hard beans accumulate and are progressively slid over
the edge into baskets. They are next steeped for a night in water,
thoroughly washed in the morning, and afterwards dried in the sun. They
are now ready for the peeling mill, a wooden edge wheel turned
vertically by a horse yoked to the extremity of its horizontal axis. In
travelling over the coffee, it bursts and detaches the coriaceous or
parchment-like skin which surrounds each hemispherical bean. It is then
freed from the membranes by a winnowing machine, in which four pieces of
tin made fast to an axle are caused to revolve with great velocity. Corn
fanners would answer better than this rude instrument of negro
invention. The coffee is finally spread upon mats or tables, picked
clean, and packed up for shipment.

The most highly esteemed coffee is that of Moka. It has a smaller and a
rounder bean; a more agreeable taste and smell than any other. Its
colour is yellow. Next to it in European reputation is the Martinique
and Bourbon coffees; the former is larger than the Arabian and more
oblong; it is rounded at the ends; its colour is greenish, and it
preserves almost always a silver gray pellicle, which comes off in the
roasting. The Bourbon coffee approaches nearest to the Moka from which
it originally sprung. The Saint Domingo coffee has its two extremities
pointed, and is much less esteemed than the preceding.

The coffee tree flourishes in hilly districts where its root can be kept
dry, while its leaves are refreshed with frequent showers. Rocky ground,
with rich decomposed mould in the fissures, agrees best with it. Though
it would grow, as we have said, to the height of 15 or 20 feet, yet it
is usually kept down by pruning to that of five feet for increasing the
production of the fruit, as well as for the convenience of cropping. It
begins to yield fruit the third year, but is not in full bearing till
the fifth, does not thrive beyond the twenty-fifth, and is useless in
general at the thirtieth. In the coffee husbandry, the plants should be
placed eight feet apart, as the trees throw out extensive horizontal
branches, and in holes ten or twelve feet deep to secure a constant
supply of moisture.

Coffee has been analysed by a great many chemists, with considerable
diversity of results. The best analysis perhaps is that of Schrader. He
found that the raw beans distilled with water in a retort communicated
to it their flavour and rendered it turbid, whence they seem to contain
some volatile oil. On reboiling the beans, filtering, and evaporating
the liquor to a syrup, adding a little alcohol till no more matter was
precipitated, and then evaporating to dryness, he obtained 17·58 per
cent. of a yellowish-brown transparent extract, which constitutes the
characteristic part of coffee, though it is not in that state the pure
proximate principle, called _cafeine_. Its most remarkable reaction is
its producing, with both the protoxide and the peroxide salts of iron, a
fine grass green colour, while a dark green precipitate falls, which
re-dissolves when an acid is poured into the liquor. It produces on the
solution of the salts of copper scarcely any effect, till an alkali be
added, when a very beautiful green colour is produced which may be
employed in painting. Coffee beans contain also a resin, and a fatty
substance somewhat like suet. According to Robiquet, ether extracts from
coffee beans nearly 10 per cent. of resin and fat, but he probably
exaggerates the amount. The peculiar substance cafeine contained in the
above extract is crystallizable. It is remarkable in regard to
composition, that after urea and the uric acid, it is among organic
products the richest in azote. It was discovered and described in 1820
by Runge. It does not possess alkaline properties. Pfaff obtained only
90 grains of cafeine from six pounds of coffee beans. There is also an
acid in raw coffee to which the name of _cafeic acid_ has been given.
When distilled to dryness and decomposed, it has the smell of roasted
coffee.

Coffee undergoes important changes in the process of roasting. When it
is roasted to a yellowish brown it loses, according to Cadet, 12-1/2 per
cent. of its weight, and is in this state difficult to grind. When
roasted to a chestnut brown it loses 18 per cent., and when it becomes
entirely black, though not at all carbonised, it has lost 23 per cent.
Schrader has analyzed roasted coffee comparatively with raw coffee, and
he found in the first 12-1/2 per cent. of an extract of coffee, soluble
in water and alcohol, which possesses nearly the properties of the
extract of the raw coffee, although it has a deeper brown colour, and
softens more readily in the air. He found also 10·4 of a blackish brown
gum; 5·7 of an oxygenated extract or rather _apothème_ soluble in
alcohol, insoluble in water; 2 of a fatty substance and resin; 69 of
burnt vegetable fibre, insoluble. On distilling roasted coffee with
water, Schrader obtained a product which contained the aromatic
principle of coffee; it reddened litmus paper, and exhaled a strong and
agreeable odour of roasted coffee. If we roast coffee in a retort, the
first portions of the aromatic principle of coffee condense into a
yellow liquid in the receiver; and these may be added to the coffee
roasted in the common way, from which this matter has been expelled and
dissipated in the air.

Chenevix affirmed that by the roasting of coffee a certain quantity of
tannin possessing the property of precipitating gelatine is generated.
Cadet made the same observation, and found, moreover, that the tannin
was most abundant in the lightly roasted coffee, and that there was
nearly none of it in coffee highly roasted. Payssé and Schrader, on the
contrary, state that solution of gelatine does not precipitate either
the decoction of roasted coffee or the alcoholic extract of this coffee.
Runge likewise asserts that he could obtain no precipitate with
gelatine; but he says that albumen precipitates from the decoction of
roasted coffee the same kind of tannin as is precipitated from raw
coffee by the acetate of lead, and set free from the lead by
sulphuretted hydrogen. With these results my own experiments agree.
Gelatine certainly does not disturb clear infusion of roasted coffee,
but the salts of iron blacken it.

Schrader endeavoured to roast separately the different principles of
coffee, but none of them exhaled the aromatic odour of roasted coffee
except the horny fibrous matter. He therefore concludes that this
substance contributes mainly to the characteristic taste of roasted
coffee, which cannot be imitated by any other vegetable matter, and
which, as we have seen, should be ascribed chiefly to the altered cafeic
acid. According to Garot we may extract the cafeine without alteration
from roasted coffee by precipitating its decoction by subacetate of
lead, treating the washed precipitate with sulphuretted hydrogen, and
evaporating the liquid product to dryness.

Of late years, much ingenuity has been expended in contriving various
forms of apparatus for making infusions of coffee for the table. I have
tried most of them, and find, after all, none so good as a _cafetière à
la Belloy_, the coffee _biggin_, with the perforated tin plate strainer,
especially when the filtered liquor is kept simmering in a close vessel,
set over a lamp or steam pan. The useful and agreeable matter in coffee
is very soluble: it comes off with the first waters of infusion, and
needs no boiling.

To roast coffee rightly we should keep in view the proper objects of
this process, which are to develop its aroma, and destroy its toughness,
so that it may be readily ground to powder. Too much heat destroys those
principles which we should wish to preserve, and substitutes new ones
which have nothing in common with the first, but add a disagreeable
empyreumatic taste and smell. If, on the other hand, the rawness or
greenness is not removed by an adequate heat, it masks the flavour of
the bean, and injures the beverage made with it. When well roasted in
the sheet iron cylinders set to revolve over a fire, it should have a
uniform chocolate colour, a point readily hit by experienced roasters,
who now manage the business very well for the principal coffee dealers
both of London and Paris, so far as my judgment can determine. The
development of the proper aroma is a criterion by which coffee roasters
frequently regulate their operations. When it loses more than 20 per
cent. of its weight, coffee is sure to be injured. It should never be
ground till immediately before infusion.


COKE, is carbonized pitcoal. See CHARCOAL; and PITCOAL at the end.


COLCOTHAR OF VITRIOL, (_Rouge d’Angleterre_, Fr.; _Rothes Eisenoxyd_,
Germ.) is the brown-red peroxide of iron, produced by calcining sulphate
of iron with a strong heat, levigating the resulting mass, and
elutriating it into an impalpable powder. A better way of making it so
as to complete the separation of the acid, is to mix 100 parts of the
green sulphate of iron with 42 of common salt, to calcine the mixture,
wash away the resulting sulphate of soda, and levigate the residuum. The
sulphuric acid in this case expels the chlorine of the salt in the form
of muriatic acid gas, and saturates its alkaline base produced by the
chemical reaction; whence an oxide will be obtained free from acid, much
superior to what is commonly found in the shops. The best sort of
polishing powder called _jewellers’ red rouge_ or plate powder is the
precipitated oxide of iron prepared by adding solution of soda to
solution of copperas, washing, drying, and calcining the powder in
shallow vessels with a gentle heat, till it assumes a deep brown red
colour. See IRON.


COLOPHANY, black rosin, the solid residuum of the distillation of
turpentine, when all the oil has been worked off.


COLOURING MATTER. (_Matière colorante_, Fr.; _Farbstoff_, Germ.) See
DYEING, the several dye-stuffs and pigments.


COLUMBIUM, a peculiar metal extracted from a rare mineral brought from
Haddam in Connecticut. It is also called Tantalium from the mineral
_tantalite_ and _yttrotantalite_, found in Sweden. It has hitherto no
application to the arts. It combines with two successive doses of
oxygen; by the second it becomes an acid.


COLZA, is a variety of cabbage, the _brassica oleracea_, whose seeds
afford, by pressure, an oil much employed in France and Belgium for
burning in lamps, and for many other purposes. This plant requires a
rich but light soil; it does not succeed upon either sandy or clayey
lands. The ground for it must be deeply ploughed and well dunged. It
should be sown in July, and be afterwards replanted in a richly manured
field. In October it is to be planted out in beds, 15 or 18 inches
apart. Colza may also be sowed in furrows 8 or 10 inches asunder.

Land which has been just cropped for wheat is that usually destined to
colza; it may be fresh dunged with advantage. The harvest takes place in
July, with the sickle, a little before the seeds are completely ripe,
lest they should drop off. As the seed is productive of oil, however,
only in proportion to its ripeness, the cut plants are allowed to
complete their maturation, by laying them in heaps under airy sheds, or
placing them in a stack, and thatching it with straw.

The cabbage stalks are thrashed with flails, the seeds are winnowed,
sifted, spread out in the air to dry; then packed away in sacks, in
order to be subjected to the oil mill at the beginning of winter. The
oil-cake is a very agreeable food to cattle, and serves to fatten them.
It is reckoned to defray the cost of the mill.

Colza impoverishes the soil very much, as do, indeed, all the plants
cultivated for the sake of their oleaginous seeds. It must not,
therefore, be come back upon again for six years, if fine crops be
desired. The double ploughing which it requires, effectually cleans the
ground. See OILS, UNCTUOUS.


COMB, the name of an instrument made of a thin plate either plane or
curved of wood, horn, tortoise-shell, ivory, bone, or metal, cut out
upon one or both of its sides or edges, into a series of somewhat long
teeth, not far apart; which is employed for disentangling, laying
parallel and smooth the hairs of man, horses, or other animals.

A thin steel saw bow, mounted in an iron or wooden handle, is the
implement used by the comb-maker to cut the bone, ivory, and wood into
slices of from a twelfth to a quarter of an inch thick, and of a size
suitable to that of the comb. The pieces of tortoise-shell as found in
commerce are never flat, or, indeed, of any regular curvature, such as
the comb must have. They are therefore steeped in boiling water
sufficiently long to soften them, and set to cool in a press between
iron or brass moulds, which impart to them the desired form which they
preserve after cooling. After receiving their outline shape, and
curvature, by proper flat files or fine rasps, the place of the teeth is
marked with a triangular file, and then the teeth themselves are cut out
with a double saw, composed of two thin slips of tempered steel, such as
the main-spring of a watch, notched with very fine sharp teeth. These
slips are mounted in a wooden or iron stock or handle, in which they may
be placed at different distances to suit the width of the comb teeth. A
comb-maker, however, well provided in tools, has an assortment of double
saws set at every ordinary width. The two slips of this saw have their
teeth in different planes, so that when it begins to cut, the most
prominent slip alone acts, and when the teeth of this one have fairly
entered into the comb, the other parallel blade begins to saw. The
workman, meanwhile, has fixed the plate of tortoise-shell or ivory
between the flat jaws of two pieces of wood, like a vice made fast to a
bench, so that the comb intended to be cut is placed at an angle of 45°
with the horizon. He now saws perpendicularly, forming two teeth at a
time, proceeding truly in the direction of the first tracing.

A much better mode of making combs is to fix upon a shaft or arbour in a
lathe a series of circular saws, with intervening brass washers or discs
to keep them at suitable distances; to set in a frame like a vice, in
front of these saws, the piece of ivory or horn to be cut; and to press
it forward upon the saws at an angle of 45 degrees, by means of a
regulated screw motion. When the teeth are thus cut, they are smoothed
and polished with files, and by rubbing with pumice stone and tripoli.

Mr. Bundy, of Camden Town, obtained a patent so long ago as 1796, for an
apparatus of that kind, which had an additional arbour fitted with a
series of circular saws, or rather files, for sharpening the points of
the comb teeth.

More recently, Mr. Lyne has invented a machine in which, by means of
pressure, two combs are cut out at once with chisels from any tough
material, such as horn or tortoise-shell, somewhat softened at the
moment by the application of a heated iron to it. The piece of horn is
made fast to a carriage, which is moved forwards by means of a screw
until it comes under the action of a ratchet-wheel, toothed upon a part
of its circumference. The teeth of this wheel bring a lever into action,
furnished with a chisel or knife, which cuts out a double comb from the
flat piece, the teeth of which combs are opposite to each other. By this
means no part of the substance is lost, as in sawing out combs. The same
carriage may be used, also, to bear a piece of ivory in the hard state
towards a circular saw, on the principles above explained, with such
precision, that from 80 to 100 teeth can be formed in the space of one
inch by a proper disposition of the tool.

Bullocks’ horns, after the tips are sawed off, are roasted in the flame
of a wood fire, till they are sufficiently softened; when they are slit
up, pressed in a machine between two iron plates, and then plunged into
a trough of cold water, whereby they are hardened. A paste of quicklime,
litharge, and water is used to stain the horn to resemble
tortoise-shell. See HORN.


COMBINATION (_Combinaison_, Fr.; _Verbindung_, Germ.); a chemical term
which denotes the intimate union of dissimilar particles of matter, into
a homogeneous looking compound, possessed of properties generally
different from those of the separate constituents.


COMBUSTIBLE (Eng. and Fr.; _Brennstoff_, Germ.); any substance which
exposed in the air to a certain temperature, consumes spontaneously with
the emission of heat and light. All such combustibles as are cheap
enough for common use go under the name of Fuel; which see. Every
combustible requires a peculiar pitch of temperature to be kindled,
called its _accendible_ point. Thus phosphorus, sulphur, hydrogen,
carburetted hydrogen, carbon, each takes fire at successively higher
heats.


COMBUSTION (Eng. and Fr.; _Verbrennung_, Germ.) results in common cases
from the mutual chemical reaction of the combustible, and the oxygen of
the atmosphere, whereby a new compound is formed; the heat and light
evolved being most probably produced by the rapid motions of the
particles during the progress of this combination.


COMPOUND COLOURS. If the effects of the colouring particles did not vary
according to the combinations which they form, and the actions exercised
upon them by the different substances present in a dyeing bath, we might
determine with precision the shade which ought to result from the
mixture of any two colours, or of the ingredients affording these
colours separately. Though the chemical action of the mordants, and of
the liquor in the dye-bath often changes the results, yet theory may
always predict them within a certain degree. It is not the colour
appropriate to the dye-stuffs which is to be considered as the
constituent part of compound colours, but that which they must assume
with a certain mordant and dye-bath. Our attention ought therefore to be
directed principally to the operation of the chemical agents employed.

1. The mixture of blue and yellow dyes produces green. D’Ambourney,
indeed, says that he has extracted a fast green from the fermented juice
of the berries of the buckthorn (_rhamnus frangula_), but no dyer would
trust to such a colour.

2. The mixture of red and blue produces violet, purple, _columbine_
(dove-colour), pansy, amaranth, lilac, mallow, and a great many other
shades, determined by the nature and tone of the red and blue
dye-stuffs, as well as their relative proportions in the bath.

3. The mixture of red and yellow produces orange, _mordoré_, cinnamon,
_coquelicot_, brick, capuchin; with the addition of blue, olives of
various shades; and with duns instead of yellows, chestnut, snuff, musk,
and other tints.

4. Blacks of the lighter kinds constitute grays; and, mixed with other
colours, produce _marrone_ (marroons), coffees, damascenes. For further
details upon this subject, see CALICO PRINTING, DYEING, as also the
individual colours in their alphabetical places.


CONCRETE. The name given by architects to a compact mass of pebbles,
sand and lime cemented together, in order to form the foundations of
buildings. Semple says that the best proportions are 80 parts of
pebbles, each about 7 or 8 ounces in weight, 40 parts sharp river sand,
and 10 of good lime; the last is to be mixed with water to a thinnish
consistence, and grouted in. It has been found that Thames ballast, as
taken from the bed of the river, consists nearly of 2 parts of pebbles
to 1 of sand, and therefore answers exceedingly well for making
concrete; with from one-seventh to one-eighth part of lime. The best
mode of making concrete, according to Mr. Godwin, is to mix the lime,
previously ground, with the ballast in a dry state; sufficient water is
now thrown over it to effect a perfect mixture, after which it should be
turned over at least twice with shovels, or oftener; then put into
barrows, and wheeled away for use instantly. It is generally found
advisable to employ two sets of men to perform this operation, with
three in each set; one man to fetch the water, &c., while the other two
turn over the mixture to the second set, and they, repeating the
process, turn over the concrete to the barrow-men. After being put into
the barrows, it should at once be wheeled up planks, so raised as to
give it a fall of some yards, and thrown into the foundation, by which
means the particles are driven closer together, and greater solidity is
given to the whole mass. Soon after being thrown in, the mixture is
observed usually to be in commotion, and much heat is evolved with a
copious emission of vapour. The barrow-load of concrete in the fall
spreading over the ground, will form generally a stratum of from 7 to 9
inches thick, which should be allowed to set before throwing in a
second.

Another method of making concrete, is first to cover the foundation with
a certain quantity of water, and then to throw in the dry mixture of
ballast and lime. It is next turned and levelled with shovels; after
which more water is pumped in, and the operation is repeated. The former
method is undoubtedly preferable.

In some cases it has been found necessary to mix the ingredients in a
pug-mill, as in mixing clay, &c. for bricks. For the preparation of a
concrete foundation, as the hardening should be rapid, no more water
should be used than is absolutely necessary to effect a perfect mixture
of the ingredients. Hot water accelerates the induration. There is about
one-fifth of contraction in volume in the concrete, in reference to the
bulk of its ingredients. To form a cubical yard of concrete, about 30
feet cube of ballast and 3-1/2 feet cube of ground lime must be
employed, with a sufficient quantity of water.


CONGELATION (Eng. and Fr.; _Gefrierung_, Germ.); the act of freezing
liquids. Many means are supplied by chemistry of effecting or promoting
this process, but they do not constitute any peculiar art or
manufacture. See ICE-HOUSE.


COOLING OF FLUIDS. In Mr. Derosnes’s method, the cooling agents employed
are a current of atmospheric air, and warm water of the same or nearly
the same temperature as that of the vapours which are to be operated
upon.

_Fig._ 295. represents merely a diagram of the general features of an
apparatus constructed upon the principles proposed to be employed,
which will serve to explain the nature of this improvement.

[Illustration: 295]

Let A be the source of the vapours, or the vessel, boiler, alembic, or
closed pan that contains the liquid or syrup to be evaporated or
concentrated. The pipe B, through which the vapour passes as it rises in
the boiler, is surrounded by another tube C, of larger diameter, closed
at both ends. A pump D, draws from the reservoir E, warm water, which
water has been heated by its previous and continual passage through the
apparatus in contact with the surface of the vapour pipes. This pump
forces the water by the pipe F, into the annular space or chamber
between the pipes B and C, in which chamber, by its immediate contact
with the pipe B, it acquires the temperature of the vapours intended to
be refrigerated. The pipe G conveys the water from the pipe C, into the
annular colander or sieve H, which has a multitude of small holes
pierced through its under part, and from whence the warm water descends
in the form of a continued shower of rain. To the end of the pipe B, a
distiller’s worm I I, is connected, which is placed beneath the colander
H. The entire length of the worm-pipe should be bound round with linen
or cotton cloth, as a conductor of the heat, which cloth will be
continually moistened by the rain in its descent from the colander. As
this water has been heated in passing along the tube C, the shower of
rain descending from the colander will be at a higher temperature than
that of the atmosphere, and, consequently, by heating the surrounding
air as it descends, a considerable upward draft will be produced through
the coils of the worm-pipe.

If the colander and the worm-pipe are enclosed within a chimney or
upright tube, as K K, open at top and bottom, a current of ascending air
will be produced within it by the descending shower of hot water,
similar in effect to that which would be produced in a chimney
communicating with a furnace, or to that of the burner of an argand
lamp. Consequently, it will be perceived that in opposition to the
descending rain, a strong upward current of air will blow through that
part of the cylinder K K, which is beneath the colander. When the air
first enters the lower aperture of the chimney or tube K, it is of the
same temperature and moisture as the external atmosphere; but in its
passage up the tube it meets with a warmer and damper atmosphere, caused
by the heat given out from the hot fluid continually passing through the
pipes, and by the hot shower of rain, and also by the steam evolved from
the surfaces of the coils of the worm, which are continually wetted by
the descending rain, the evaporation being considerably augmented by the
cloth bound round the worm-pipe, retaining the water as it descends in
drops from coil to coil.

The atmosphere within the tube being of a higher temperature than
without, a current of air constantly ascends and escapes at the upper
aperture K, and its place is supplied by fresh air from the surrounding
atmosphere, entering the tube below. The fresh air thus admitted at the
bottom of the tube being cold and dry, will be suited to take up the
heat and moisture within, because the water within the tube being in a
state of dispersion as rain, presents to the air many points, or a very
extended surface, and also because it is of a higher temperature than
the air; and, besides, cold dry air is continually renewed, and a source
of warmth is furnished by the latent caloric to the steam, as fast as it
is evolved. Thus a portion of the descending rain, or water, is
evaporated, and the effect of this evaporation is to subtract caloric
not only from the water held in contact with the coils of the worm-pipe
by the cloth enveloping it, but also from the hot vapours which pass
through the worm. This process of evaporation has, therefore, a cooling
power, which is but slight in the lower part of the chimney or tube K;
because the temperature of the water, or rain, and of the worm, at this
part, are of a lower temperature; but its refrigerating power increases
as it rises towards the colander, and there it acquires its maximum of
intensity, so that at any point between the lower aperture of the
cylinder and the colander, the current of air is always a little cooler
than the atmosphere of the region through which it passes (that is, at
its maximum); and in passing this region of higher temperature, it is
not only put in equilibrium of temperature, but also made to take up an
additional quantity of aqueous vapours, which equalises the new
temperature it acquires with its capacity of saturation. The cooling
caused by the evaporation acts in an incessant and progressive manner
from the lower aperture of the cylinder to the under side of the
colander; and this cooling not only acts as an agent of the evaporation
which the current of air cools, but it refrigerates also, because it
becomes warmed in abstracting caloric from the vapours or liquids
passing through the worm; and this refrigeration acts also incessantly
and progressively from the lower part of the tube or chimney to the
colander.

The patentee states, in conclusion, that “the velocity or force of the
current of air that passes through the chimney or tube K, can be
accelerated by artificial means, either by conducting the air and vapour
passing from the upper aperture of the cylinder into the chimney or
flues of a furnace, or by means of a revolving, forcing, or exhausting
fan, or ventilator, or any other contrivance which will produce an
increased current of air, but which it is not necessary to be
particularly described, as I only wish to explain the principles of a
simple apparatus, constructed in any convenient form; and I would
remark, that the area of the lower aperture through which the air is
introduced into the chimney or tube K, and also the area of the upper
aperture, or that through which it passes to the atmosphere, should be
in accordance with the effect intended to be obtained.

“It is further to be remarked, that in order to obtain from this
apparatus the best effect, the velocity of the current of air must be
itself a maximum; and as the speed or velocity of the current of air is
owing to and determined by the excess of the temperature of the
descending water, or rain, and of the coils of the worm to that of the
exterior atmosphere, it ensues that the temperature of the water, or
rain, must be a maximum. But this excess of temperature is a maximum
only when the source of the rain is at the same temperature as the
vapours to be condensed: if less warm, it would attract less air; or, if
warmer, it would augment the temperature of the vapours intended to be
condensed. Consequently, the shower of water employed in the tube K, as
the agent for cooling, bestows its maximum of effect when it is as warm
as the vapours to be condensed; therefore, I may express this
proposition, viz., ‘That in refrigerating with water, less of it may be
expended when it is warm than when it is cold, and that the least
quantity of water will be evaporated when it is as warm as the aqueous
or spirituous vapours upon which it is to operate.’

“This proposition may appear strange, nevertheless it is conformable to
the laws of nature; and appears only strange, because until now warm
water has not been employed with currents of air for refrigerating.

“Hence it is necessary to raise the temperature of the water in the
colander to the temperature of the vapours to be condensed: therefore, I
cause the lukewarm water, pumped from the reservoir E, to circulate in
the chamber C. In this circulation it also begins to act as a
refrigerating medium, taking up a portion of heat from the vapours that
pass through the pipe B, and afterwards it acts as a further condenser
in the cylinder, in the way described. Finally, the portion of this
water that is still in the fluid state, after having fallen down from
coil to coil, arrives lukewarm to the inclined surface L, which conducts
it into the reservoir E, from whence it is pumped up into the chamber C,
as before described.

“The tube or chimney K, may have more or less altitude; the higher it is
the greater is the current produced. The force or velocity of the
current of air can be governed by the areas of the introduction and exit
apertures. If the cylinder rises only to the height of the sieve, the
effect is much less than when it is prolonged beyond this height. I
would further remark, that if the cylinder was removed, a slight effect
might be produced, provided that a current of air be preserved in the
cylindrical space limited by the coils of the worm, and also if the
current was produced between the coils; or a central passage might be
formed in an apparatus of another shape than that above described.

“I have only shown the application of the worm, because intending only
to explain the principles of this method of condensing and
refrigerating.

“The small quantity of water wasted in this manner of condensation,
(that is, that portion passed off to the atmosphere in the form of
vapours, at the upper aperture of the cylinder K,) may be replaced by a
small stream of cold water, which may be brought to the apparatus, and
perhaps most conveniently introduced into the reservoir E, or into the
chamber between the pipes B and C. When operating upon aqueous vapours,
the waste of water is always less in weight than that of the vapours
liquefied. When this apparatus is applied to the purposes of
distillation, the end of the worm should terminate in a vessel M, which
is to receive the produce of the condensation. It will be seen that this
improved process is applicable to various purposes, where condensation
or refrigeration is required; for instance, in the boiling or
concentration of sugar; to condensing and refrigerating distilled
vapours, or steam, or saline liquids, either in vacuum or not; to
cooling brewers’ worts; and to the refrigeration of other liquors, or
any other processes, when it may be required.”

I have inserted the specification of this patent _verbatim_. M. Derosne
has busied himself during a long life with a prodigious number of
ingenious little contrivances for clarifying and boiling syrups,
distillation, &c., but he has in this invention taken a bolder flight,
having secured the exclusive privilege of condensing vapours, and
cooling liquors, with hot water, in preference to cold. No man at all
versant in the scientific doctrines, or the practical applications of
caloric, will ever seek to meddle with his monopoly of such a scheme. He
may find, perhaps, some needy coppersmith ready to espouse that or any
other equally foolish project, provided a productive job can be made of
it, against credulous customers.

For some rational methods of cooling liquors, and condensing vapours,
see REFRIGERATION, STILL, and SUGAR.


COPAL, a resin which exudes spontaneously from two trees, the _Rhus
copallinum_, and the _Elæocarpus copalifer_, the first of which grows in
America, and the second in the East Indies. A third species of copal
tree grows on the coasts of Guinea, especially on the banks of some
rivers, among whose sands the resin is found. It occurs in lumps of
various sizes and of various shades of colour, from the palest greenish
yellow to darkish brown. I found its specific gravity to vary in
different specimens from 1·059 to 1·071, being intermediate in density
between its two kindred resins, animé and amber. Some rate its specific
gravity so high as 1·139, which I should think one of the errors with
which chemical compilations teem. Copal is too hard to be scratched by
the nail, whence the excellence of its varnish. It has a conchoidal
fracture, and is without smell or taste. When exposed to heat in a glass
retort over a spirit lamp it readily melts into a liquid, which being
further heated boils with explosive jets. A viscid oily-looking matter
then distils over. After continuing the process for some time, no
succinic acid is found in the receiver, but the copal blackens in the
retort. Anhydrous alcohol boiled upon it, causes it to swell, and
transforms it by degrees into an elastic viscid substance. It is not
soluble in alcohol of 0·825 at the boiling point, as I have ascertained.
Copal dissolves in ether, and this ethereous solution may be mixed with
alcohol without decomposition. Caoutchoucine acts very slightly upon it
by my experiments, even at the boiling temperature of this very volatile
fluid; but a mixture of it with alcohol of 0·825 in equal parts
dissolves it very rapidly in the cold into a perfectly liquid varnish.
Alcohol holding camphor in solution also dissolves it, but not nearly so
well as the last solvent. According to Unverdorben, copal may be
completely dissolved by digesting one part of it for 24 hours with one
part and a half of alcohol (probably anhydrous), because that portion of
copal which is insoluble in alcohol, dissolves in a very concentrated
solution of the soluble portion. Oil of petroleum and turpentine
dissolve only 1 or 2 per cent. of raw copal. By particular management,
indeed, oil of turpentine may be combined with copal, as we shall
describe under the article VARNISH.

Fused copal possesses different properties from the substance in its
solid state; for it then may be made to combine both with alcohol and
oil of turpentine.

Unverdorben has extracted from the copal of Africa, five different kinds
of resin, none of which has however been applied to any use in the arts.

The ultimate constituents of copal by my analysis are, carbon 79·87,
hydrogen 9·00, oxygen 11·1; being of hydrogen 7·6 in excess above the
quantity necessary to form water with the oxygen. Of copal and animé,
551,166 libs. were imported in 1835.


COPPER is one of the metals most anciently known. It was named from the
island of Cyprus, where it was extensively mined and smelted by the
Greeks. It has a reddish brown colour inclining to yellow; a faint but
nauseous and rather disagreeable taste; and when rubbed between the
fingers it imparts a smell somewhat analogous to its taste. Its specific
gravity is from 8·8 to 8·9. It is much more malleable than it is
ductile; so that far finer leaves may be obtained from it than wire. It
melts at the 27th degree of Wedgewood’s pyrometer, and at a higher
temperature it evaporates in fumes which tinge the fire of a bluish
green. By exposure to heat with access of air, it is rapidly converted
into black scales of peroxide. In tenacity it yields to iron; but
surpasses gold, silver, and platinum, considerably in this respect.

In mineralogy, the genus copper includes about 13 different species, and
each of these contains a great many varieties. These ores do not possess
any one general exterior character by which they can be recognized; but
they are readily distinguished by chemical re-agents. Water of ammonia
digested upon any of the cupreous ores in a pulverized state, after they
have been calcined either alone or with nitre, assumes an intense blue
colour, indicative of copper. The richest of the ordinary ores appear
under two aspects; the first class has a metallic lustre, a copper red,
brass yellow, iron gray, or blackish gray colour, sometimes inclining to
blue; the second is without metallic appearance, has a red colour,
verging upon purple, blue, or green, the last tint being the most usual.
Few copper ores are to be met with, indeed, which do not betray the
presence of this metal by more or less of a greenish film.

1. _Native copper_, occurs in crystals, branches and filaments, its most
common locality being in primitive rocks. It is found abundantly in
Siberia, at the mines of Tourinski, in those of Hungary, of
Fundo-Moldavi in Gallicia, of Fahlun in Sweden, of Cornwall, &c. The
gangues of native copper are granite, gneiss, mica-slate, clay-slate,
quartz, carbonate or fluate of lime, sulphate of barytes, &c. The most
remarkable masses of native copper hitherto observed were; first, one in
Brazil, 14 leagues from Basa, which weighed 2616 pounds; and secondly,
another which Dr. Francis-le-Baron discovered in America to the south of
Lake Superior. It was nearly 15 feet in circumference.

2. _Sulphuret of Copper, the vitreous ore of Brochant._ The texture of
this ore is compact: its fracture, conchoidal, surface sometimes dull;
colour, iron black or lead gray, often bluish, iridescent, or reddish
from a mixture of protoxide. It is easily melted even by the heat of a
candle; but more difficult of reduction than protoxide. This ore yields
to the knife, assuming a metallic lustre when cut. Its density varies
from 4·8 to 5·34. Its composition according to Klaproth is 78·5 copper,
18·5 sulphur, with a little iron and silica. Its equivalent constitution
by theory is 80 copper + 20 sulphur = 100; whence 78·5 of metal should
be associated with 19·6 of sulphur. This ore is therefore one of the
richest ores, and forms very powerful veins, which likewise contain some
orange protoxide. It is to be found in all considerable copper
districts; in Siberia, Saxony, Sweden, and especially Cornwall, where
the finest crystals occur.

3. _Copper Pyrites_, resembles in its metallic yellow hue, sulphuret of
iron; but the latter is less pale, harder, and strikes fire more easily
with steel. It presents the most lively rainbow colours. Its specific
gravity is 4·3. It contains generally a good deal of iron; as the
following analysis will show; copper 30, sulphur 37, iron 33, in 100
parts. According to Hisinger, the Swedish pyrites contains 63 of copper,
12 of iron, and 25 of sulphur. These ores occur in primitive and
transition districts in vast masses and powerful veins; and are commonly
accompanied with gray copper, sulphuret of iron, sparry iron, sulphurets
of lead, and zinc.

4. _Gray Copper_, has a steel gray colour, more or less deep, either
shining or dull; fracture uneven; a distinct metallic lustre; difficult
of fusion at the blowpipe; it communicates to glass of borax a
yellowish-red colour. Its density in crystals is 4·86. Its composition
is very variable; consisting essentially of copper, iron, antimony, and
sulphur. The exploration of this ore is profitable, in consequence of
the silver which it frequently contains. It occurs in primitive
mountains; and is often accompanied with red silver ore, copper pyrites,
and crystallized quartz.

5. _Protoxide of Copper_, or _red oxide of Copper_: its colour is a deep
red, sometimes very lively, especially when bruised. It is friable,
difficult of fusion at the blowpipe, reducible on burning charcoal,
soluble with effervescence in nitric acid, forming a green liquid. Its
constitution when pure, is 88·9 copper + 11·1 oxygen = 100.

6. _Black oxide of Copper_, is of a velvet black, inclining sometimes to
brown or blue; and it acquires the metallic lustre on being rubbed. It
is infusible at the blowpipe. Its composition is, copper 80 + oxygen 20;
being a true peroxide.

7. _Hydrosilicate of Copper_, consists essentially of oxide of copper,
silica, and water. Its colour is green; and its fracture is conchoidal
with a resinous lustre, like most minerals which contain water. Its
specific gravity is 2·73. It is infusible at the blowpipe alone, but it
melts easily with borax.

8. _Dioptase Copper_, or _Emerald Malachite_; a beautiful but rare
cupreous mineral, consisting of oxide of copper, carbonate of lime,
silica, and water in varying proportions.

9. _Carbonate of Copper_, _Malachite_; is of a blue or green colour. It
occurs often in beautiful crystals.

10. _Sulphate of Copper_, _Blue Vitriol_, similar to the artificial salt
of the laboratory. The blue water which flows from certain copper mines,
is a solution of this salt. The copper is easily procured in the
metallic state by plunging pieces of iron into it.

11. _Phosphate of Copper_, is of an emerald green, or verdigris colour
with some spots of black. It presents fibrous or tuberculous masses with
a silky lustre in the fracture. It dissolves in nitric acid without
effervescence, forming a blue liquid; melts at the blowpipe, and is
reducible upon charcoal, with the aid of a little grease, into a
metallic globule. Its powder does not colour flame green, like the
powder of muriate of copper.

12. _Muriate of Copper_, is green of various shades; its powder imparts
to flame a remarkable blue and green colour. It dissolves in nitric acid
without effervescence; and is easily reduced before the blowpipe. Its
density is 3·5. By Klaproth’s analysis it consists of oxide of copper
73, muriatic acid 10, water 17.

13. _Arseniate of Copper._ It occurs in beautiful blue crystals. Before
the blowpipe it melts exhaling fumes of a garlic odour, and it affords
metallic globules when in contact with charcoal. See more upon the ores
at the end of this article.

In the article METALLURGY, I have described the mode of working certain
copper mines; and shall content myself here with giving a brief account
of two cupreous formations, interesting in a geological point of view;
that of the copper slate of Mansfeldt, and of the copper veins of
Cornwall.

The curious strata of bituminous schist in the first of these
localities, are among the most ancient of any which contain the exuviæ
of organised bodies not testaceous. From among their tabular slabs the
vast multitudes of fossil fish were extracted, which have rendered the
cantons of Mansfeldt, Eisleben, Ilmenau, and other places in Thuringia
and Voigtland so celebrated. Many of the fish are transformed into
copper pyrites. Here, also, have been found the fossil remains of the
lizard family, called _Monitors_.

Such is the influence of a wise administration upon the prosperity of
mines, that the thin layer of slate in this formation, of which 100
pounds commonly contain but one pound and a half of copper, occasionally
argentiferous, has been for several centuries the object of smelting
works of the greatest importance to the territory of Mansfeldt and the
adjoining country.

The frequent derangements which this metallic deposit experiences, led
skilful directors of the under-ground operations at an early period to
study the order of superposition of the accompanying rocks. From their
observations, there resulted a system of facts which have served to
guide miners, not only in the country of Mansfeldt, but over a great
portion of Germany, and in several other countries where the same series
of rocks, forming the immediate envelope of the cupreous schists, were
found to occur in the same order of superposition.

_Of the English copper works._--The deposits of copper in Cornwall occur
always as veins in granite, or in the schistose rocks which surround and
cover it; and hence, the Cornish miners work mostly in the granite or
greenish clay slate; the former of which they call _growan_, the latter
_killas_. But tin is sometimes disseminated in small veins in porphyry
or _elvan_, which itself forms great veins in the above rocks. No
stratification has been observed in Cornwall.

The copper veins are abundant in the killas and rare in the granite; but
most numerous near the line of junction of the two rocks. The different
kinds of mineral veins in Cornwall may be classed as follows:--

1. Veins of elvan; elvan courses, or elvan channels.

2. Tin veins, or tin _lodes_; the latter word being used by the Cornish
miners to signify a vein rich in ore, and the word _course_, to signify
a barren vein.

3. Copper veins running east and west; east and west copper lodes.

4. Second system of copper veins, or _contra_ copper lodes.

5. Crossing veins; cross courses.

6. Modern copper veins; more recent copper lodes.

7. Clay veins; of which there are two sets, the more ancient, called
_Cross-Fluckans_; and the more modern, called _Slides_.

There are therefore three systems of copper veins in Cornwall; of which
the first is considered to be the most ancient, because it is always
traversed by the two others, and because, on the contrary, it never cuts
them off. The width of these veins does not exceed 6 feet, though
occasional enlargements to the extent of 12 feet sometimes take place.
Their length is unknown, but the one explored in the _United Mines_ has
been traced over an extent of seven miles. The gangue of these veins is
generally quartz, either pure, or mixed with green particles analogous
to chlorite. They contain iron pyrites, blende, sulphuret, and several
other compounds of copper, such as the carbonate, phosphate, arseniate,
muriate, &c. The most part of the copper veins are accompanied with
small argillaceous veins, called by the miners _fluckan of the lode_.
These are often found upon both sides of the vein, so as to form cheeks
or _salebandes_.

When two veins intersect each other, the direction of the one thrown out
becomes an object of interest to the miner and geologist. In Saxony it
is regarded as a general fact that the rejected portion is always to the
side of the _obtuse angle_; this also holds generally in Cornwall, and
the more obtuse the angle of incidence, the more considerable the
out-throw.

The great copper vein of _Carharack_, in the parish of Gwenap, is a most
instructive example of intersection. The power of this vein is 8 feet;
it runs nearly from east to west, and dips towards the north at an
inclination of 2 feet in a fathom. Its upper part is in the killas, its
lower part in the granite. The vein has suffered two intersections; the
first results from encountering the vein called _Steven’s fluckan_,
which runs from north-east to south-west, throwing it out several
fathoms. The second has been caused by another vein, almost at right
angles to the first, and which has driven it 20 fathoms out to the right
side. The fall of the vein occurs, therefore, in one case to the right,
and in the other to the left; but in both instances, it is to the side
of the obtuse angle. This disposition is very singular; for one portion
of the vein appears to have ascended, while another has sunk.

The mining works in the copper veins are carried on by reverse steps;
see MINES. The grand shafts for drainage and extraction are vertical,
and open upon the roof side of the vein, traversing it to a certain
depth. These pits are sunk to the lowest point of the exploration; and,
in proportion as the workings descend, by means of excavations in the
vein, the pits are deepened and put into communication towards their
bottom with each new gallery of elongation, by means of transverse
galleries. At present, the main shafts are fully 160 fathoms deep. Their
horizontal section is oblong, and is divided into two compartments; the
one destined for extraction, the other for the pumps. Their timbering
has nothing remarkable, but is executed with every attention to economy,
the whole wood employed in these mines being brought from Norway.

The descent of the workmen is effected by inclined shafts scooped out of
the vein; the ladders are slightly inclined; they are interrupted every
10 fathoms by floors; the steps are made of iron, and, to prevent them
from turning under the foot, the form of a miner’s punch or jumper has
been given them, the one end being round, and the other being
wedge-shaped.

The ore is raised either by means of horse-gins, or by steam-engine
power most frequently of high pressure. I shall take the _Consolidated
Mines_ as an example.

The draining, which is one of the most considerable sources of expense,
both from the quantity of water, and from the depth of the mine, is
executed by means of sucking and forcing pumps, the whole piston-rods of
which, 120 feet long, are attached to a main-rod suspended at the
extremity of the working beam of a steam-engine.

On this mine three steam-engines are erected of very great power, for
the purpose of drainage; the one called the _Maria_ engine is of the
first-rate force, and most improved construction. The cylinder is 90
inches in internal diameter, and the length of the stroke is 9 feet 11
inches. It works single stroke, and is encased in a coating of bricks to
prevent dissipation of the heat. The vapour is admitted at the upper end
of the cylinder during the commencement of the fall of the piston, at a
pressure capable of forming an equilibrium with a column of 60 inches of
mercury. The introduction of the steam ceases whenever the piston has
descended through a certain space, which may be increased or diminished
at pleasure. During the remainder of the descent the piston is pressed
merely by this vapour in its progressive expansion, while the under side
of the piston communicates with the condenser. It ascends by the
counterweight at the pump end of the working beam. Hence, it is only
during the descent of the piston, that the effective stroke is exerted.
Frequently the steam is admitted only during the sixth part of the
course of the piston, or 18 inches. In this way the power of the engine
is proportioned to the work to be done; that is, to the body of water to
be raised. The _maximum_ force of the above engine is about 310 horses;
though it is often made to act with only one third of this power.

The copper mines of the isle of Anglesey, those of North Wales, of
Westmoreland, the adjacent parts of Lancashire and Cumberland, of the
south west of Scotland, of the Isle of Man, and of the south east of
Ireland, occur also in primitive or transition rocks. The ores lie
sometimes in masses, but more frequently in veins. The mine of Ecton in
Staffordshire, and that of Cross-gill-burn, near Alston-moor in
Cumberland, occur in transition or metalliferous limestone.

The copper ores extracted both from the granitic and schistose
localities, as well as from the calcareous, are uniformly copper pyrites
more or less mixed with iron pyrites; the red oxide, carbonate,
arseniate, phosphate, and muriate of copper, are very rare in these
districts.

The working of copper in the isle of Anglesey may be traced to a very
remote era. It appears that the Romans were acquainted with the Hamlet
mine near Holyhead; but it was worked with little activity till about 70
years ago. This metalliferous deposit lies in a greenish clay slate,
passing into talc slate; a rock associated with serpentine and euphotide
(_gabbro_ of Von Buch). The veins of copper are from one to two yards
thick; and they converge towards a point where their union forms a
considerable mass of ore. On this mass the mine was first pierced by an
open excavation, which is now upwards of 300 feet deep, and appears from
above like a vast funnel. Galleries are formed at different levels upon
the flank of the excavation to follow the several small veins, which run
in all directions, and diverge from a common centre like so many radii.
The ore receives in these galleries a kind of sorting, and is raised by
means of hand windlasses, to the summit of a hill, where it is cleaned
by breaking and riddling.

The water is so scanty in this mine that it is pumped up by a six-horse
steam-engine. A great proportion of it is charged with sulphate of
copper. It is conveyed into reservoirs containing pieces of old iron;
the sulphate is thus decomposed into copper of cementation. The Anglesea
ore is poor, yielding only from 2 to 3 _per cent._ of copper: a portion
of its sulphur is collected in roasting the ore.

_Mechanical preparation of the copper ores in Cornwall._--The ore
receives a first sorting, either within the mine itself, or at its
mouth, the object of which is to separate all the pieces larger than a
walnut. These are then reduced by the hammer to a smaller size; after
which the whole are sorted into four lots, according to their relative
richness. The fragments of poor ore are pounded in the stamps so that
the metallic portion may be separated by washing.

The rich ore is broken into small bits, of the size of a nut, with a
flat beater, formed of a piece of iron 6 inches square and 1 inch
thick, adapted to a wooden handle. The ore to be broken is placed upon
plates of cast-iron; each about 16 inches square and 1-1/2 inch thick.
These iron plates are set towards the edge of a small mound about a yard
high, constructed with dry stones rammed with earth. The upper surface
of this mound is a little inclined from behind forwards. The work is
performed by women, each furnished with a beater; the ore is placed in
front of them beyond the plates; they break it, and strew it at their
feet, whence it is lifted and disposed of to the smelting-houses.

Inferior ores, containing a notable proportion of stony matters, are
also broken with the beater, and the rich parts are separated by
riddling and washing from the useless matters.

The smaller ore is washed on a sieve by shaking it in a stream of water,
which carries away the lighter stony pieces, and leaves the denser
metalliferous. They are then sorted by hand. Thus by beating, stamping,
and riddling in water, the stony substances are in a great measure
separated. The finer ground matter is washed on a plane table, over
which a current of water is made to flow. Finally, the ore nearly fine
is put into a large tub with water, and briskly stirred about with a
shovel, after which it settles in the order of richness, the pure
metallic ore being nearest the bottom. The stamps used for copper ore in
Cornwall are the same as those used for tin ores, of which we shall
speak in treating of the latter metal, as well as of the boxes for
washing the fine powder or _slime_. These in fact do not differ
essentially from the stamping mills and washing apparatus described in
the article METALLURGY. Crushing rolls are of late years much employed.
See LEAD and TIN.

Cornwall being destitute of coal, the whole copper ore which this county
produces is sent for smelting to South Wales. Here are 15 copper works
upon the Swansea and Neath, which pursue a nearly uniform and much
improved process, consisting in a series of calcinations, fusions, and
roastings, executed upon the ores and the matters resulting from them.

The furnaces are of the reverberatory construction; they vary in their
dimensions and in the number of their openings, according to the
operations for which they were intended. There are 5 of them:--1. The
calcining furnace or calciner; 2. The melting furnace; 3. The roasting
furnace or roaster; 4. The refining furnace; 5. The heating or igniting
furnace.

[Illustration: 296 297 298]

1. The calcining furnace rests upon a vault, C, into which the ore is
raked down after being calcined; it is built of bricks, and bound with
iron bars, as shown in the elevation, _fig._ 296. The hearth, B B,
_figs._ 296. and 298. is placed upon a level with the lower horizontal
binding bar, and has nearly the form of an ellipse, truncated at the two
extremities of its great axis. It is horizontal, bedded with fire-bricks
set on edge, so that it may be removed and repaired without disturbing
the arch upon which it reposes. Holes, not visible in the figure, are
left in the shelves before each door, _c c_, through which the roasted
ore is let fall into the subjacent vault. The dimensions of the hearth B
B are immense, being from 17 to 19 feet in length, and from 14 to 16 in
breadth. The fire-place, A, _fig._ 298., is from 4-1/2 to 5 feet long,
and 3 feet wide. The bridge or low wall, _b_, _fig._ 302., which
separates the fire-place from the hearth, is 2 feet thick; and in Mr.
Vivian’s smelting-works is hollow, as shown in the figure, and
communicates at its two ends with the atmosphere, in order to conduct a
supply of fresh air to the hearth of the furnace. This judicious
contrivance will be described in explaining the _roasting_ operation.
The arched roof of the furnace slopes down from the bridge to the
beginning of the chimney, _f_, _fig._ 296, 298., its height above the
hearth being at the first point about 26 inches, and from 8 to 12 at the
second.

Such great calcining furnaces have 4 or 5 doors, _c c c c_, _fig._ 298.,
one for the fire-place, as shown at the right hand in _fig._ 297., and 3
or 4 others for working the ore upon the reverberatory hearth. If there
be 3, 2 of them are placed between the vertical binding bars upon one
side, and a third upon the opposite side of the furnace; if there be 4,
2 are placed upon each side, facing one another. These openings are 12
inches square, and are bound with iron frames. The chimney is about 22
feet high, and is placed at one angle of the hearth, as at _f_, _fig._
298., being joined by an inclined flue to the furnace.

For charging it with ore there is usually placed above the upper part of
the vault 2 hoppers, E E, in a line with the doors; they are formed of 4
plates of iron, supported in an iron frame. Beneath each of them there
is an orifice for letting the ore down into the hearth.

These furnaces serve for calcining the ore, and the _matts_ or _crude
coppers_: for the latter purpose, indeed, furnaces of two stories are
sometimes employed, as represented in _fig._ 301. The dimensions of each
floor in this case are a little less than the preceding. Two doors, _c
c_, correspond to each hearth, and the workmen, while employed at the
upper story, stand upon a raised movable platform.

[Illustration: 299, 300]

2. _Melting furnace_, _figs._ 299 and 300.--The form of the hearth is
also elliptical, but the dimensions are smaller than in the calcining
furnace. The length does not exceed 11 or 11-1/2 feet, and the breadth
varies from 7 to 8. The fire-place is however larger in proportion, its
length being from 3-1/2 feet to 4, and its breadth from 3 to 3-1/2; this
size being requisite to produce the higher temperature of this furnace.
It has fewer openings, there being commonly three; one to the fire-place
at D, a second one, O, in the side, kept generally shut, and used only
when incrustations need to be scraped off the hearth, or when the
furnace is to be entered for repairs; and the third or working-door, G,
placed on the front of the furnace beneath the chimney. Through it the
scoriæ are raked out, and the melted matters are stirred and puddled,
&c.

The hearth is bedded with infusible sand, and slopes slightly towards
the side door, to facilitate the discharge of the metal. Above this door
there is a hole in the wall of the chimney (_fig._ 300.) for letting the
metal escape. An iron gutter, O, leads it into a pit, K, bottomed with
an iron receiving-pot, which may be lifted out by a crane. The pit M is
filled with water, and the metal becomes granulated as it falls into the
receiver. The melting furnaces are surmounted by a hopper, L, as shown
in _fig._ 299.

[Illustration: 301]

Melting furnaces are sometimes used also for calcination. There are some
such near Swansea, which serve this double purpose; they are composed of
3 floors (_fig._ 301.) The floor A is destined for melting the calcined
ore; the other two, B C, serve for calcination. The heat being less
powerful, upon the upper sole C, the ore gets dried upon it, and begins
to be calcined--a process completed on the next floor. Square holes,
_d_, left in the hearths B and C, put them in communication with each
other, and with the lower one A; these perforations are shut during the
operation by a sheet of iron, removable at pleasure.

The hearths _b_ and _c_ are made of bricks; they are horizontal at top
and slightly vaulted beneath; they are 2 bricks thick, and their
dimensions are larger than those of the inferior hearths, as they extend
above the fire-place. On the floors destined for calcination the furnace
has two doors on one of its sides: on the lower story there are also
two; but they are differently collocated. The first, being in the front
of the furnace, serves for drawing off the scoriæ, for working the
metal, &c.; and the second, upon the side, admits workmen to make
necessary repairs. Below this door the discharge or tap-hole A is
placed, which communicates by a cast-iron gutter with a pit filled with
water. The dimensions of this furnace in length and breadth are nearly
the same as those of the melting furnace above described; the total
height is nearly 12 feet. It is charged by means of one or two hoppers.

3. _Roasting furnace._--The furnaces employed for this purpose are in
general analogous to the calcining ones; but in the smelting works of
Hafod, the property of Messrs. Vivian, these furnaces, alluded to above,
present a peculiar construction, for the purpose of introducing a
continuous current of air upon the metal, in order to facilitate its
oxidizement. This process was originally invented by Mr. Sheffield, who
disposed of his patent right to Messrs. Vivian.

[Illustration: 302]

The air is admitted by a channel, _c c_, through the middle of the
fire-bridge, _fig._ 302, and extending all its length; it communicates
with the atmosphere at its two ends _c c_; square holes, _b b_, left at
right angles to this channel, conduct the air into the furnace. This
very simple construction produces a powerful effect in the roasting
operation. It not only promotes the oxidizement of the metals, but burns
the smoke, and assists in the vaporisation of the sulphur; while by
keeping the bridge cool it preserves it from wasting, and secures
uniformity of temperature to the hearth.

4. _Refining furnace._--In this, as in the melting furnace, the sole
slopes towards the door in front, instead of towards the side doors,
because in the refining furnace the copper collects into a cavity formed
in the hearth towards the front door, from which it is lifted out by
ladles; whereas, in the melting furnaces, the metal is run out by a
tap-hole in the side. The hearth sole is laid with sand; but the roof is
higher than in the melting furnace, being from 32 to 36 inches. If the
top arch were too much depressed, there might be produced upon the
surface of the metal a layer of oxide very prejudicial to the quality of
the copper. When the metal in that case is run out, its surface
solidifies and cracks, while the melted copper beneath breaks through
and spreads irregularly over the cake. This accident, called the _rising
of the copper_, hinders it from being laminated, and requires it to be
exposed to a fresh refining process, when lead must be added to dissolve
the oxide of copper. This is the only occasion upon which the addition
of lead is proper in refining copper. When the metal to be refined is
mixed with others, particularly with tin, as in extracting copper from
old bells, then very wide furnaces must be employed, to expose the
metallic bath upon a great surface, and in a thin stratum, to the
oxidizing action of the air.

The door G, _fig._ 300., upon the side of the refining furnace, is very
large, and is shut with a framed brick door, balanced by a
counter-weight. This door being open during the refining process, the
heat is stronger at B than at A (_figs._ 299, 300.)

5. _Heating furnaces_, being destined to heat the pigs or bars of copper
to be laminated, as well as the copper sheets themselves, are made much
longer in proportion to their breadth. Their hearth is horizontal, the
vault not much depressed; they have only one door, placed upon the side,
but which extends nearly the whole length of the furnace: this door may
be raised by means of a counter-weight, in the same way as in the
furnaces for the fabrication of sheet-iron and brass.

_Series of operations to which the ore is subjected._--The ores which
are smelted in the Swansea works are cupreous pyrites, more or less
mingled with _gangue_ (vein-stone). The pyrites is composed of nearly
equal proportions of sulphuret of copper and sulphuret of iron.

The earthy matters which accompany the pyrites are usually siliceous,
though in some mines the metalliferous deposit is mixed with clay or
fluate of lime. Along with these substances, pretty uniformly
distributed, tin and arsenical pyrites occur occasionally with the
copper; and though these two metals are not chemically combined, yet
they cannot be separated entirely in the mechanical preparations. The
constituent parts of the ore prepared for smelting are, therefore,
copper, iron, sulphur, with tin, arsenic, and earthy matters in some
cases. The different ores are mixed in such proportions that the average
metallic contents may amount to 8-1/2 per cent. The smelting process
consists in alternate roastings and fusions. The following description
of it is chiefly taken from an excellent paper, published by John
Vivian, esq., in the Annals of Philosophy for 1823.

In the roasting operation the volatile substances are disengaged mostly
in the gaseous state, while the metals that possess a strong affinity
for oxygen become oxidized. In the fusion the earthy substances combine
with these oxides, and form glassy scoriæ or slags, which float upon the
surface of the melted metal.

These calcinations and fusions take place in the following order:--

1. Calcination of the ore. 2. Melting of the calcined ore. 3.
Calcination of the coarse metal. 4. Melting of the calcined coarse
metal. 5. Calcination of the fine metal (second matt). 6. Melting of the
calcined fine metal. 7. Roasting of the coarse copper. In some smelting
works, this roasting is repeated four times; in which case a calcination
and a melting are omitted. In the Havod works, however, the same saving
is made without increasing the number of roastings. 8. Refining or
toughening the copper.

Besides these operations, which constitute the treatment of copper
properly speaking, two others are sometimes performed, in which only the
scoriæ are melted. These may be designated by the letters _a_ and _b_.
_a_ is the re-melting of the portion of the scoriæ of the second
process, which contain some metallic granulations. _b_ is a particular
melting of the scoriæ of the fourth operation. This fusion is intended
to concentrate the particles of copper in the scoriæ, and is not
practised in all smelting works.

_First operation. Calcination of the ore._--The different ores, on
arriving from Cornwall and other districts where they are mined, are
discharged in continuous cargoes at the smelting works, in such a way,
that by taking out a portion from several heaps at a time, a tolerably
uniform mixture of ores is obtained; which is very essential in a
foundry, because, the ores being different in qualities and contents,
they act as fluxes upon each other. The ore thus mixed is transported
to the works in wooden measures that hold a hundred-weight. The workmen
entrusted with the calcination convey the ore into the hoppers of the
calcining furnace, whence it falls into the hearth; other workmen spread
it uniformly on the surface by iron rakes. The charge of a furnace is
from three tons to three tons and a half. Fire is applied and gradually
increased, till, towards the end of the operation, the temperature be as
high as the ore can support without melting or agglutinating. To prevent
this running together, and to aid the extrication of the sulphur, the
surfaces are renewed, by stirring up the ore at the end of every hour.
The calcination is usually completed at the end of 12 hours, when the
ore is tumbled into the arch under the sole of the furnace. Whenever the
ore is cold enough to be moved, it is taken out of the arch, and
conveyed to the calcined heap.

The ore in this process hardly changes weight, having gained in
oxidizement nearly as much as it has lost in sulphur and arsenic; and if
the roasting has been rightly managed, the ore is in a black powder,
owing to the oxide of iron present.

_Second operation. Fusion of the calcined ore._--The calcined ore is
likewise given to the melters in measures containing a hundred-weight.
They toss it into hoppers, and after it has fallen on the hearth, they
spread it uniformly. They then let down the door, and lute it tightly.
In this fusion there are added about 2 cwt. of scoriæ proceeding from
the melting of the calcined matt, to be afterwards described. The object
of this addition is not only to extract the copper that these scoriæ may
contain, but especially to increase the fusibility of the mixture.
Sometimes also, when the composition of the ore requires it, lime, sand,
or fluor spar is added; and particularly the last fluxing article.

The furnace being charged, fire is applied, and the sole care of the
founder is to keep up the heat so as to have a perfect fusion; the
workman then opens the door, and stirs about the liquid mass to complete
the separation of the metal (or rather of the matt) from the scoriæ, as
well as to hinder the melted matter from sticking to the sole. The
furnace being ready, that is, the fusion being perfect, the founder
takes out the scoriæ by the front door, by means of a rake. When the
matt is thus freed from the scoriæ, a second charge of calcined ore is
then introduced to increase the metallic bath; which second fusion is
executed like the first. In this way, new charges of roasted ore are put
in till the matt collected on the hearth rises to a level with the
door-way, which happens commonly after the third charge. The tap hole is
now opened; the matt flows out into the pit filled with water, where it
is granulated during its immersion; and it collects in the pan placed at
the bottom. The granulated matt is next conveyed into the matt
warehouse. The oxidation with which the grains get covered by the action
of the water, does not allow the proper colour of the matt or coarse
metal to be distinguished; but in the bits which stick in the gutter, it
is seen to be of a steel gray. Its fracture is compact, and its lustre
metallic. The scoriæ often contain metallic grains; they are broken and
picked with care. All the portions which include some metallic particles
are re-melted in an accessory process. The rejected scoriæ have been
found to be composed of siliceous matter 59, oxide of copper 1, oxide of
tin 0·7.

In this operation, the copper is concentrated by the separation of a
great part of the matters with which it was mixed or combined. The
granulated matt produced, contains in general 33 per cent. of copper; it
is therefore four times richer than the ore; and its mass is
consequently diminished in that proportion. The constituent parts are
principally copper, iron, and sulphur.

The most important point to hit in the fusion just described, is to make
a fusible mixture of the earths and the oxides, so that the matt of
copper may, in virtue of its greater specific gravity, fall to the
under-part, and separate exactly from the slag. This point is attained
by means of the metallic oxides contained in the scoriæ of the fourth
operation, of which 2 cwt. were added to the charge. These consist
almost entirely of black oxide of iron. When the ores are very difficult
to melt, a measure of about half a hundred-weight of fluor spar is
added; but this must be done with precaution, for fear of increasing the
scoriæ too much.

The business goes on day and night. Five charges are commonly put
through hands in the course of 24 hours; but when all circumstances are
favourable, that is to say, when the ore is fusible, when the fuel is of
the first quality, and when the furnace is in good condition, even six
charges a day have been despatched.

The charge is a ton and a half of calcined ore, so that a melting
furnace corresponds nearly to a calcining furnace; the latter turning
out nearly 7 tons of calcined ore in 24 hours.

The workmen are paid by the ton.

_Third operation. Calcination of the coarse metal, or the matt._--The
object of this operation is principally to oxidize the iron, an
oxidation easier to execute, than in the first calcining, because the
metal is now disengaged from the earthy substances, which screened it
from the action of the air.

This calcination is executed in the furnace already represented, _fig._
296, 297, 298. page 318. exactly in the same way as the ore was
calcined. The metal must be perpetually stirred about, to expose all its
surfaces to the action of the hot air, and to hinder the clotting
together. The operation lasts 24 hours; during the first six, the fire
should be very moderate, and thereafter gradually increased to the end
of the calcination. The charge is, like that of the first, 3 tons and a
half.

_Fourth operation. Melting of the calcined coarse metal, or calcined
matt._--In the fusion of this first calcined matt, some scoriæ of the
latter operations must be added, which are very rich in oxide of copper,
and some crusts from the hearth, which are likewise impregnated with it.
The proportion of these substances varies according to the quality of
the calcined matt.

In this second fusion, the oxide of copper contained in the scoriæ, is
reduced by the affinity of the sulphur, one portion of which passes to
the state of acid, while the other forms a subsulphuret with the copper
become free. The matt commonly contains a sufficient quantity of sulphur
to reduce the oxide of copper completely; but if not, which may happen
if the calcination of the matt has been pushed too far, a small quantity
of uncalcined matt must be introduced, which, by furnishing sulphur,
diminishes the richness of the scoriæ, and facilitates the fusion.

The scoriæ are taken out by the front door, by drawing them forward with
a rake. They have a great specific gravity; are brilliant with metallic
lustre, very crystalline, and present, in the cavities, crystals like
those of pyroxene; they break easily into very sharp-edged fragments.
They contain no granulated metal in the interior; but it sometimes
occurs, on account of the small thicknesses of the stratum of scoriæ,
that these carry off with them, when they are withdrawn, some metallic
particles.

These scoriæ, as we have already stated, under the fusion of the roasted
ore, are in general melted with it. In some cases, however, a special
melting is assigned to them.

The matt obtained in this second fusion is either run out into water
like the first, or moulded into pigs (ingots), according to the mode of
treatment which it is to undergo. This matt, called by the smelters
_fine metal_ when it is granulated, and _blue metal_ when it is in pigs,
is of a light grey colour, compact, and bluish at the surface. It is
collected in the first form when it is to be calcined anew; and in the
second, when it must immediately undergo the operation of _roasting_.
Its contents in copper are 60 _per cent._ This operation, which is but
sometimes had recourse to, lasts 5 or 6 hours. The charge is 1 ton.

(_b_) _Particular fusion of the scoriæ of the fourth operation._--In
re-melting these scoriæ, the object is to procure the copper which they
contain. To effect this fusion, the scoriæ are mixed with pulverized
coal, or other carbonaceous matters. The copper and several other metals
are deoxidized, and furnish a white and brittle alloy. The scoriæ
resulting from this melting are in part employed in the first melting,
and in part thrown away. They are crystalline, and present crystals
often in the cavities, which appear to belong to bisilicate of iron.
They have a metallic lustre, and break into very sharp-edged fragments.
The white metal is melted again, and then united to the product of the
second fusion.

_Fifth operation. Calcination of the second matt, or fine metal of the
smelter._--This is executed in precisely the same way as that of the
first matt. It lasts 24 hours; and the charge is usually 3 tons.

_Sixth operation. Melting of the calcined fine metal._--This fusion is
conducted like that of the first matt. The black copper, or coarse
copper, which it produces, contains from 70 to 80 per cent. of pure
metal; it is run into ingots, in order to undergo the operation of
roasting.

The scoriæ are rich in copper; they are added to the fusion of the
calcined coarse metal of the fourth operation.

In the smelting houses of Messrs. Vivian, at Hafod, near Swansea, the
fifth and sixth operations have been omitted of late years. The second
matt is run into pigs, under the name of _blue metal_, to be immediately
exposed to the roasting.

The disposition of the canal _a a´_, _fig._ 302., which introduces a
continuous current of air to the hearth of the furnace, accelerates and
facilitates the calcination of the matt; an advantage which has
simplified the treatment, by diminishing the number of calculations.

_Seventh operation. Roasting of the coarse copper, the product of the
sixth operation._ The chief object of this operation is oxidizement; it
is performed either in an ordinary roasting furnace, or in the one
belonging to _fig._ 302., which admits a constant current of air. The
pigs of metal derived from the preceding melting are exposed, on the
hearth of the furnace, to the action of the air, which oxidizes the iron
and other foreign metals with which the copper is still contaminated.
The duration of the roasting varies from 12 to 24 hours, according to
the degree of purity of the crude copper. The temperature should be
graduated, in order that the oxidizement may have time to complete, and
that the volatile substances which the copper still retains may escape
in the gaseous form. The fusion must take place only towards the end of
the operation.

The charge varies from a ton and a quarter to a ton and a half. The
metal obtained is run out into moulds of sand. It is covered with black
blisters, like steel of cementation; whence it has got the name of
blistered copper. In the interior of these pigs, the copper presents a
porous texture, occasioned by the ebullition produced by the escape of
the gases during the moulding. The copper being now almost entirely
purged from the sulphur, iron, and the other substances with which it
was combined, is in a fit state to be refined. This operation affords
some scoriæ; they are very heavy, and contain a great deal of oxide of
copper, sometimes even metallic copper.

These scoriæ, as well as those of the third melting and of the refining,
are added to the second fusion, as we have already stated, in describing
the fourth operation.

In some works, the roasting is repeated several times upon the _blue
metal_, in order to bring it to a state fit for refining. We shall
afterwards notice this modification of the treatment.

_Eighth operation. Refining or toughening._--The pigs of copper intended
for refining are put upon the sole of the refining furnace through the
door in the side. A slight heat is first given, to finish the roasting
or oxidation, in case this operation has not already been pushed far
enough. The fire is to be increased by slow degrees, so that, by the end
of 6 hours, the copper may begin to flow. When all the metal is melted,
and when the heat is considerable, the workman lifts up the door in the
front, and withdraws with a rake the few scoriæ which may cover the
copper bath. They are red, lamellated, very heavy, and closely resemble
protoxide of copper.

The refiner takes then an assay with a small ladle, and when it cools,
breaks it in a vice, to see the state of the copper. From the appearance
of the assay, the aspect of the bath, the state of the fire, &c., he
judges if he may proceed to the toughening, and what quantity of wooden
spars and wood charcoal he must add to render the metal malleable, or,
in the language of the smelters, bring it to the proper pitch. When the
operation of refining begins, the copper is brittle or dry, and of a
deep red colour approaching to purple. Its grain is coarse, open, and
somewhat crystalline.

To execute the refining, the surface of the metal is covered over with
wood charcoal, and stirred about with a spar or rod of birch wood. The
gases which escape from the wood, occasion a brisk effervescence. More
wood charcoal is added from time to time, so that the surface of the
metal may be always covered with it, and the stirring is continued with
the rods, till the operation of refining be finished; a circumstance
indicated by the assays taken in succession. The grain of the copper
becomes finer and finer, and its colour gradually brightens. When the
grain is extremely fine, or _closed_, when the trial pieces half cut
through and then broken, present a silky fracture, and when the copper
is of a fine light red, the refiner considers the operation to be
completed; but he verifies still further the purity of the copper, by
trying its malleability. For this purpose, he takes out a sample in his
small ladle, and pours it into a mould. When the copper is solidified,
but still red-hot, he forges it. If it is soft under the hammer, if it
does not crack on the edges, the refiner is satisfied with its
ductility, and he pronounces it to be in its _proper state_. He orders
the workmen to mould it; who then lift the copper out of the furnace in
large iron ladles lined with clay, and pour it into moulds of the size
suitable to the demands of commerce. The ordinary dimensions of the
ingots or pigs are 12 inches broad, 18 long, and from 2 to 2-1/2 thick.

The period of the refining process is 20 hours. In the first six, the
metal heats, and suffers a kind of roasting; at the end of this time it
melts. It takes four hours to reach the point at which the refining,
properly speaking, begins; and this last part of the process lasts about
4 hours. Finally, 6 hours are required to arrange the moulds, cast the
ingots, and let the furnace cool.

The charge of copper in the refining process depends upon the dimensions
of the furnace. In the Hafod works, one of the most important in
England, the charge varies from 3 to 5 tons; and the quantity of pure
copper manufactured in a week is from 40 to 50 tons.

The consumption of fuel is from 15 to 18 parts of coal, for one part of
refined copper in pigs.

When the copper offers difficulties in the refining, a few pounds of
lead are added to it. This metal, by the facility with which it
scorifies, acts as a purifier, aiding the oxidation of the iron and
other metals that may be present in the copper. The lead ought to be
added immediately after removing the door to skim the surface. The
copper should be constantly stirred up, to expose the greatest possible
surface to the action of the air, and to produce the complete oxidation
of the lead; for the smallest quantity of this metal alloyed in copper,
is difficult to clear up in the lamination; that is to say, the scale of
oxide does not come cleanly from the surface of the sheets.

The operation of refining copper is delicate, and requires, upon the
part of the workmen, great skill and attention to give the metal its due
ductility. Its surface ought to be entirely covered with wood charcoal;
without this precaution, the refining of the metal would _go back_, as
the workmen say, during the long interval which elapses in the moulding;
whenever this accident happens, the metal must be stirred up anew with
the wooden pole.

Too long employment of the wooden rod gives birth to another remarkable
accident, for the copper becomes more brittle than it was prior to the
commencement of the refining; that is, when it was _dry_. Its colour is
now of a very brilliant yellowish red, and its fracture is fibrous. When
this circumstance occurs, when the refining, as the workmen say, has
_gone too far_, the refiner removes the charcoal from the top of the
melted metal; he opens the side door, to expose the copper to the action
of the air, and it then resumes its malleable condition.

Mr. Vivian, to whom we owe the above very graphic account of the
processes, has explained, in a very happy manner, the theory of
refining. He conceives, we may conclude, that the copper in the _dry
state_, before the refining, is combined with a small portion of oxygen,
or, in other words, that a small portion of oxide of copper is diffused
through the mass, or combined with it; and that this proportion of
oxygen is expelled by the deoxidizing action of the wood and charcoal,
whereby the metal becomes malleable. 2. That when the refining process
is carried too far, the copper gets combined with a little charcoal.
Thus copper, like iron, is brittle when combined with oxygen and
charcoal; and becomes malleable only when freed entirely from these two
substances.

It is remarkable, that copper, in the _dry state_, has a very strong
action upon iron; and that the tools employed in stirring the liquid
metal become very glistening, like those used in a farrier’s forge. The
iron of the tools consumes more rapidly at that time, than when the
copper has acquired its malleable state. The metal requires, also, when
_dry_, more time to become solid, or to cool, than when it is refined; a
circumstance depending, probably, upon the difference in fusibility of
the copper in the two states, and which seems to indicate, as in the
case of iron, the presence of oxygen.

When the proper refining point has been passed, another very remarkable
circumstance has been observed; namely, that the surface of the copper
oxidizes more difficultly, and that it is uncommonly brilliant;
reflecting clearly the bricks of the furnace vault. This fact is
favourable to the idea suggested above, that the metal is in that case
combined with a small quantity of carbon; which absorbs the oxygen of
the air, and thus protects the metal from its action.

Copper is brought into the market in different forms, according to the
purposes which it is to serve. What is to be employed in the manufacture
of brass is granulated. In this condition it presents more surface to
the action of zinc or calamine, and combines with it more readily. To
produce this granulation, the metal is poured into a large ladle,
pierced with holes, and placed above a cistern filled with water, which
must be hot or cold, according to the form wished in the grains. When it
is hot, round grains are obtained analogous to lead shot; and the copper
in this state is called _bean shot_. When the melted copper falls into
cold water perpetually renewed, the granulations are irregular, thin,
and ramified; constituting _feathered shot_. The _bean shot_ is the form
employed in brass making.

Copper is also made into small ingots, about 6 ounces in weight. These
are intended for exportation to the East Indies, and are known in
commerce by the name of Japan copper. Whenever these little pieces are
solidified, they are thrown, while hot, into cold water. This immersion
slightly oxidizes the surface of the copper, and gives it a fine red
colour.

Lastly, the copper is often reduced into sheets, for the sheathing of
ships, and many other purposes. The Hafod works possess a powerful
rolling mill, composed of four pairs of cylinders. It is moved by a
steam engine, whose cylinder has 40 inches diameter. See the
representation of the rolling mill of the Royal Mint, under GOLD.

The cylinders for rolling copper into sheets are usually 3 feet long,
and 15 inches in diameter. They are uniform. The upper roller may be
approached to the under one, by a screw, so that the cylinders are
brought closer, as the sheet is to be made thinner.

The ingots of copper are laid upon the sole of a reverberatory furnace
to be heated; they are placed alongside each other, and they are formed
into piles in a cross-like arrangement, so that the hot air may pass
freely round them all. The door of the furnace is shut, and the workman
looks in through a peep-hole from time to time, to see if they have
taken the requisite temperature; namely, a dull red. The copper is now
passed between the cylinders; but although this metal be very malleable,
the ingots cannot be reduced to sheets without being several times
heated; because the copper cools, and acquires, by compression, a
texture which stops the progress of the lamination.

These successive heatings are given in the furnace indicated above;
though, when the sheets are to have a very great size, furnaces
somewhat different are had recourse to. They are from 12 to 15 feet
long, and 5 wide. See BRASS.

The copper, by successive heating and lamination, gets covered with a
coat of oxide, which is removed by steeping the sheets for a few days in
a pit filled with urine; they are then put upon the sole of the heating
furnace. Ammonia is formed, which acts on the copper oxide, and lays
bare the metallic surface. The sheets are next rubbed with a piece of
wood, then plunged, while still hot, into water, to make the oxide scale
off; and lastly, they are passed cold through the rolling press to
smooth them. They are now cut square, and packed up for home sale or
exportation.

The following estimate has been given by MM. Dufrénoy and Elie de
Beaumont of the expense of manufacturing a ton of copper in South Wales.

                                                           _£_ _s._ _d._
  12-1/2 tons of ore, yielding 8-1/2 _per cent._ of copper  55   0    0
  20 tons of coals                                           8   0    0
  Workmen’s wages, rent, repairs, &c.                       13   0    0
                                                            ------------
                                                            76   0    0
                                                            ------------

The exhalations from the copper smelting works are very detrimental to
both vegetable and animal life. They consist of sulphurous acid,
sulphuric acid, arsenic and arsenious acids, various gases and fluoric
vapours, with solid particles mechanically swept away into the air,
besides the coal smoke. Mr. Vivian has invented a very ingenious method
of passing the exhalations from the calcining ores and _matts_ along
horizontal flues or rather galleries of great dimensions, with many
crossings and windings of the current, and exposure during the greater
part of the circuit to copious showers of cold water. By this simple and
powerful system of condensation, the arsenic is deposited in the bottoms
of the flues, the sulphurous acid is in a great measure absorbed, and
the nuisance is remarkably abated.

The following figures represent certain modifications of the copper
calcining and smelting copper furnaces of Swansea.

[Illustration: 303 304]

_Fig._ 304. is the section of the roasting furnace lengthwise; _fig._
303. the ground plan; in which _a_ is the fire-door; _b_ the grate; _c_
the fore-bridge; _d_ the chimney; _e e_ working apertures on each of the
long sides of the furnace, through which the ore is introduced, spread,
and turned over; _f f_ cast-iron hoppers; _g g_ openings in the vaulted
roof; _h_ the hearth-sole; _i i_ holes in this; _k_ a vaulted space
under the hearth. The hearth has a suitable oval shape, and is covered
with a flat arch. Its length is 16 feet, breadth 13-1/2, mean height 2
feet.

[Illustration: 305 306]

_Fig._ 305. is a longitudinal section of the melting furnace; _fig._
306. the ground plan in which _a_ is the fire door; _b_ the grate; _c_
the fire bridge; _d_ the chimney; _e_ the side openings; _f_ the working
doors; _g_ the raking-out hole; _h_ iron spouts, which conduct the
melted metal into pits filled with water.

The melting furnace is altogether smaller; but its firing hearth is
considerably larger than in the roasting furnace. The long axis of the
oval hearth is 14 feet; its short axis 10 feet; its mean height 2 feet.

The principal ore smelted at Chessy is the azure copper, which was
discovered by accident in 1812. Red copper ore, also, has come into
operation there since 1825. The average metallic contents of the richest
azure ore are from 33 to 36 per cent.; of the poorer, from 20 to 24. The
red ore contains from 40 to 67 parts in 100. The ore is sorted, so that
the mean contents of metal may be 27 per cent., to which 20 per cent. of
limestone are added; whence the cinder will amount to 50 per cent. of
the ore. A few per cents. of red copper slag, with some quicklime and
_gahrslag_, are added to each charge, which consists of 200 pounds of
the above mixture, and 150 pounds of coke. When the furnace (_fourneau à
manche_, see the Scotch smelting hearth, under LEAD), is in good action,
from 10 to 14 such charges are worked in 12 hours. When the crucible is
full of metal at the end of this period, during which the cinder has
been frequently raked off, the blast is stopped, and the _matt_ floating
over the metal being sprinkled with water and taken off, leaves the
black copper to be treated in a similar way, and converted into
_rosettes_. The refining of this black copper is performed in a kind of
reverberatory furnace.

The cinders produced in this reduction process are either vitreous and
light blue, which are most abundant; cellular, black, imperfectly fused
from excess of lime; or, lastly, red, dense, blistery, from defect of
lime, from too much heat, and the passage of protoxide into the cinders.
They consist of silicate of alumina, of lime, protoxide of iron; the red
contain some silicate of copper.

[Illustration: 307 308]

The copper-refining furnace at Chessy, near Lyons, is of the kind called
_Spleiss-ofen_ (split hearths) by the Germans. _Fig._ 307. is a section
lengthwise in the dotted line A B of _fig._ 308., which is the ground
plan.

The foundation-walls are made of gneiss; the arch, the fire-bridge, and
the chimney, of fire-bricks. The hearth, _a_, is formed of a dense
mixture of coal-dust, upon a bottom of well-beat clay _b_, which reposes
upon a bed of brickwork _c_. Beneath this there is a slag bottom _d_;
_e_ is the upper, and _f_ the under discharge hole. The hearth is
egg-shaped; the longer axis being 8 feet, the shorter 6-1/2 feet: in the
middle it is 10 inches deep, and furnished with the outlets _g g_, which
lead to each of the _Spleiss-hearths_ _h h_, _fig._ 308. These outlets
are contracted with fire-bricks _i i_, till the proper period of the
discharge. The two hearths are placed in communication by a canal _h_;
they are 3-1/2 feet in diameter, 16 inches deep; are floored with
well-beat coal ashes, and receive about 27 cwt. for a charge.

_l_ is the grate; _m_, the fire-bridge; _n_, the boshes in which the
_tuyères_ lie; _o_, the chimney; _p_, the working door through which the
slags may be drawn off. Above this is a small chimney, to carry off the
flame and smoke whenever the door is opened.

The smelting _post_ or charge, to be purified at once, consists of 60
cwt. of black copper, to which a little granular copper and copper of
cementation is added; the consumption of pit-coal amounts to 36 cwt. As
soon as the copper is melted, the bellows are set a-going, and the
surface of the metal gets soon covered with a moderately thick layer of
cinder, which is drawn off. This is the first skimming or _decrassage_.
By and by, a second layer of cinder forms, which is in like manner
removed; and this skimming is repeated, to allow the blast to act upon
fresh metallic surfaces. After 4 or 5 hours, no more slag appears, and
then the fire is increased. The melted mass now begins to boil or work
(_travailler_), and continues so to do, for about 3/4 of an hour, or an
hour, after which the motion ceases, though the fire be kept up. The
_gahrproof_ is now taken; but the metal is seldom fine in less than 3/4
of an hour after the boil is over. Whenever the metal is run off by the
tap-hole into the two basins _i i_, called SPLIT-HEARTHS, a reddish
vapour or mist rises from its surface, composed of an infinite number of
minute globules, which revolve with astonishing velocity upon their
axes, constituting what the Germans called _spratzen_ (crackling) of the
copper. They are composed of a nucleus of metal, covered with a film of
protoxide, and are used as sand for strewing upon manuscript. The copper
is separated, as usual, by sprinkling water upon the surface of the
melted metal, in the state of _rosettes_, which are immediately immersed
in a stream of water. This refining process lasts about 16 or 17 hours;
the skimmings weigh about 50 cwt.; the refuse is from 15 to 17 per
cent.; the loss from 2 to 3 per cent. The _gahrslag_ amounts to 11 cwt.

[Illustration: 309 310 311]

The refining of the eliquated copper (called _darrlinge_) from which the
silver has been sweated out by the intervention of lead, can be
performed only in small hearths. The following is the representation of
such a furnace, called, in German, _Kupfergahrheerd_. _Fig._ 309. is the
section lengthwise; _fig._ 310. is the section across; and _fig._ 311.
is the ground plan, in which _a_ is the hearth-hollow; _b_, a massive
wall; _c_, the mass out of which the hearth is formed; _d_, cast-iron
plates covering the hearth; _e_, opening for running off the liquid
slag; _f_, a small wall; _g_, iron curb for keeping the coals together.

The hearth being heated with a bed of charcoal, 3/4 cwt. of _darrlinge_
are laid over it, and covered with more fuel: whenever this charge is
melted, another layer of the coal and _darrlinge_ is introduced, and
thus in succession till the hearth become full, or contain from 2-1/4 to
2-1/2 cwt. In Neustadt 7-1/2 cwt. of _darrlinge_ have been refined in
one furnace, from which 5 cwt. of _gahrcopper_ has been obtained. The
blast oxidizes the foreign metals, namely, the lead, nickel, cobalt, and
iron, with a little copper, forming the _gahrslag_; which is, at first,
rich in lead oxide, and poor in copper oxide; but, at the end, this
order is reversed. The slag, at first blackish, assumes progressively a
copper red tint. The slag flows off spontaneously along the channel _e_,
from the surface of the hearth. The _gahre_ is tested by means of a
proof rod of iron, called _gahr-eisen_, thrust through the _tuyère_ into
the melted copper, then drawn out and plunged in cold water. As soon as
the _gahrspan_ (scale of copper) appears brownish red on the outside,
and copper red within, so thin that it seems like a net-work, and so
deficient in tenacity that it cannot be bent without breaking, the
refining is finished. The blast is then stopped; the coals covering the
surface, as also the cinders must be raked off the copper, after being
left to cool a little; the surface is now cooled by sprinkling water
upon it, and the thick cake of congealed metal (_rondelle_) is lifted
off with tongs, a process called _schleissen_ (slicing), or
_sheibenreissen_ (shaving), which is continued till the last convex cake
at the bottom of the furnace, styled the _kingspiece_, is withdrawn.
These _rondelles_ are immediately immersed in cold water, to prevent the
oxidation of the copper; whereupon the metal becomes of a cochineal red
colour, and gets covered with a thin film of protoxide. Its under
surface is studded over with points and hooks, the result of tearing the
congealed disc from the liquid metal. Such cakes are called _rosette_
copper. When the metal is very pure and free from protoxide, these cakes
may be obtained very thin, one 24th of an inch for example.

The refining of two cwts. and a half of _darrlinge_ takes three quarters
of an hour, and yields one cwt. and a half of _gahr copper_ in 36
rosettes, as also some _gahrslag_. Gahr copper generally contains from
1-1/2 to 2-1/2 per cent. of lead, along with a little nickel, silver,
iron, and aluminum.

_Smelting of the Mansfeldt copper schist, or bituminous
Mergelschiefer._--The cupreous ore is first roasted in large heaps, of
2000 cwts., interstratified with brush-wood, and with some slates rich
in bituminous matter, mixed with the others. These heaps are 3 ells
high, and go on burning 15 weeks in fair and 20 in rainy weather. The
bitumen is decomposed; the sulphur is dissipated chiefly in the form of
sulphurous acid; the metal gets partially oxidized, particularly the
iron, which is a very desirable circumstance towards the production of a
good smelting slag. The calcined ore is diminished one-tenth in bulk,
and one-eighth in weight; becoming of a friable texture and a dirty
yellow gray colour. The smelting furnaces are cupolas (_schachtofen_),
14 to 18 feet high; the fuel is partly wood charcoal, partly coke from
the Berlin gas-works, and Silesia. The blast is given by cylinder
bellows, recently substituted for the old barbarous _Blasebälgen_, or
wooden bellows of the household form.

The cupreous slate is sorted, according to its composition, into slate
of lime, clay, iron, &c., by a mixture of which the smelting is
facilitated. For example, 1 post or charge may consist of 20 cwt. of the
ferruginous slate, 14 of the calcareous, 6 of the argillaceous, with 3
of fluor spar, 3 of rich copper slags, and other refuse matters. The
nozzle at the _tuyère_ is lengthened 6 or 8 inches, to place the melting
heat near the centre of the furnace. In 15 hours 1 fodder of 48 cwts. of
the above mixture may be smelted, whereby 4 to 5 cwts. of _matte_ (crude
copper, called _Kupferstein_ in Germany) and a large body of slags are
obtained. The _matte_ contains from 30 to 40 per cent. of copper, and
from 2 to 4 _loths_ (1 to 2 oz.) of silver. The slags contain at times
one-tenth their weight of copper.

The _matte_ is composed of the sulphurets of copper, iron, silver, zinc,
along with some arsenical cobalt and nickel. The slaty slag is raked off
the surface of the melted _matte_ from time to time. The former is
either after being roasted six successive times, smelted into black
copper; or it is subjected to the following concentration process. It is
broken to pieces, roasted by brushwood and coals three several times in
brick-walled kilns, containing 60 cwts., and turned over after every
calcination; a process of four weeks’ duration. The thrice roasted mass,
called _spurrost_, being melted in the cupola _fig._ 313. with
ore-cinder, yields the _spurstein_, or concentrated _matte_. From 30 to
40 cwts. of spurrost are smelted in 24 hours; and from 48 to 60 per
cent. of _spurstein_ are obtained, the slag from the slate smelting
being employed as a flux. The spurstein contains from 50 to 60 per cent.
of copper, combined with the sulphurets of copper, of iron, and silver.

The spurstein is now mixed with _dünnstein_ (a sulphuret of copper and
iron produced in the original smeltings) roasted six successive times,
in a quantity of 60 cwts., with brushwood and charcoal; a process which
requires from 7 to 8 weeks. The product of this six-fold calcination is
the _Gahrrost_ of the Germans (done and purified); it has a colour like
red copper ore, varying from blue gray into cochineal red; a granular
fracture; it contains a little of the metal, and may be immediately
reduced into metallic copper, called _kupfermachen_. But before smelting
the mass, it is lixiviated with water, to extract from it the soluble
sulphate, which is concentrated in lead pans, and crystallized.

The lixiviated _gahröste_ mixed with from 1/4 to 1/5 of the lixiviated
_dünnsteinrost_, and 1/6 to 1/10 of the copper slate slag, are smelted
with charcoal or coke fuel in the course of 24 hours, in a mass of 60 or
80 cwts. The product is black copper, to the amount of about 1/4 the
weight, and 1/6 of _dünnstein_, or _thin matte_. This black copper
contains in the cwt. from 12 to 20 loths (6 to 10 oz.) of silver. The
_dünnstein_ consists of from 60 to 70 per cent. of copper combined with
sulphur, sulphuret of iron and arsenic; and when thrice roasted, yields
a portion of metal. The black copper lies undermost in the crucible of
the furnace, above it is the _dünnstein_, covered with the stone slag,
or copper cinder, resulting from the slate-smelting. The slags being
raked off, and the crucible sufficiently full, the eye or nozzle hole is
shut, the _dünnstein_ removed by cooling the surface, and breaking the
crust, which is about 1/4 to 1/2 inch thick. The same method is adopted
for taking out the black copper in successive layers. For the
de-silvering of this, and similar black coppers, see SILVER.

[Illustration: 312 313 314 315]

_Fig._ 312. is a vertical section through the form or _tuyère_ in the
dotted line A B of _fig._ 314. _Fig._ 313. is a vertical section in the
dotted line C D of _fig._ 315. _a_ is the shaft of the furnace, _b_ the
rest, _c c_ the forms; _d_ the sole or hearth-stone, which has a slope
of 3 inches towards the front wall; _e e_, &c. casing walls of fire
bricks; _f f_, &c. filling up walls built of rubbish stones; _g g_ a
mass through which the heat is slowly conducted; _h h_ the two holes
through one or other of which alternately the product of the smelting
process is run off into the fore-hearth. Beneath the hearth-sole there
is a solid body of loam; and the fore-hearth is formed with a mixture of
coal-dust and clay; _k_ is the discharge outlet. _Fig._ 314. is a
horizontal section of the furnace through the hole or eye in the dotted
line E F of _fig._ 312.; _fig._ 315. a horizontal section of the shaft
of the furnace through the form in the dotted line G H of _figs._ 312
and 313. The height of the shaft, from the line E F to the top, is 14
feet; from E to G, 25 inches; from _c_ to the line below _b_, 2 feet;
from that line to the line opposite _g g_, 2 feet. The width at the line
_g g_ is 3 feet 3 inches, and at _c_ 26 inches. The basins _i i_, _fig._
314., are 3 feet diameter, and 20 inches deep.

The refining of copper is said to be well executed at Seville, in Spain;
and, therefore, some account of the mode of operating there may be
acceptable to the reader.

The first object is to evaporate in a reverberatory furnace all the
volatile substances, such as sulphur, arsenic, antimony, &c., which may
be associated with the sulphur; and the second, to oxidize and to
convert into scoriæ the fixed substances, such as iron, lead, &c., with
the least possible expense and waste. The minute quantities of gold and
silver which resist oxidation cannot be in any way injurious to the
copper. The hearth is usually made of a refractory sand and clay with
ground charcoal, each mixed in equal volumes, and worked up into a
doughy consistence with water. This composition is beat firmly into the
furnace bottom. But a quartzose hearth is found to answer better, and to
be far more durable; such as a bed of fire-sandstone.

Before kindling the furnace, its inner surface is smeared over with a
cream-consistenced mixture of fire-clay and water.

The cast pigs, or blocks of black or crude copper, are piled upon the
hearth, each successive layer crossing at right angles the layer beneath
it, in order that the flame may have access to play upon the surface of
the hearth, and to heat it to a proper pitch for making the metal flow.

The weight of the charge should be proportional to the capacity of the
furnace, and such that the level of the metallic bath may be about an
inch above the nozzle of the bellows; for, were it higher, it would
obstruct its operation, and were it too low, the stream of air would
strike but imperfectly the surface of the metal, and would fail to
effect, or would retard at least, the refining process, by leaving the
oxidation and volatilization of the foreign metals incomplete.

As the scoriæ form upon the surface, they are drawn off with an iron
rabble fixed to the end of a wooden rod.

Soon after the copper is melted, charcoal is to be kindled in three iron
basins lined with loam, placed alongside the furnace, to prepare them
for receiving their charge of copper, which is to be converted in them,
into _rosettes_.

The bellows are not long in action before the evaporation of the mineral
substances is so copious, as to give the bath a boiling appearance; some
drops rise up to the roof of the reverberatory, others escape by the
door, and fall in a shower of minute spherical globules. This phenomenon
proves that the process is going on well; and, when it ceases, the
operation is nearly completed. A small proof of copper, of the form of a
watch-case, and therefore called _montre_, is taken out from time to
time, upon the round end of a polished iron rod, previously heated. This
rod is dipped two or three inches into the bath, then withdrawn and
immersed in cold water. The copper cap is detached from the iron rod, by
a few blows of a hammer; and a judgment is formed from its thickness,
colour, and polish, as to the degree of purity which the copper has
acquired. But these _watches_ need not be drawn till the small rain,
above spoken of, has ceased to fall. At the end of about 11 hours of
firing, the numerous small holes observable in the first _watch_ samples
begin to disappear; the outer surface passes from a bright red to a
darker hue, the inner one becomes of a more uniform colour, and always
less and less marked with yellowish spots. It will have acquired the
greatest pitch of purity that the process can bestow, when the _watches_
become of a dark crimson colour.

Care must be taken to stop this refining process at the proper time;
for, by prolonging it unduly, a small quantity of cupreous oxide would
be formed, which, finding no oxygen to reduce it, would render the whole
body of copper hard, brittle, and incapable of lamination.

The basins must now be emptied of their burning charcoal, the opening of
the _tuyère_ must be closed, and the melted copper allowed to flow into
them through the tap-hole, which is then closed with loam. Whenever the
surface is covered with a solid crust, it is bedewed with water; and as
soon as the crust is about 1-1/2 inch thick it is raised upon hooks
above the basin, to drain off any drops, and then carried away from the
furnace. If these cakes, or rosettes, be suddenly cooled by plunging
them immediately in water, they will assume a fine red colour, from the
formation of a film of oxide.

Each refining operation produces, in about 12 hours, 1-7/10 tons of
copper, with the consumption of about 4/5 of a ton of dry wood.

Care should be taken that the copper cake or _rosette_ be all solidified
before plunging it into water, otherwise a very dangerous explosion
might ensue, in consequence of the sudden extrication of oxygen from the
liquid metal, in the act of condensation. On the other hand, the cake
should not be allowed to cool too long in the air, lest it get
peroxidized upon the surface, and lose those fine red, purple, and
yellow shades, due to a film of the protoxide, which many dealers
admire.

When a little oxide of antimony and oxide of copper are combined with
copper, they occasion the appearance of micaceous scales in the
fractured faces. Such metal is hard, brittle, yellowish within, and can
be neither laminated nor wire-drawn. These defects are not owing to
arsenic, as was formerly imagined; but, most probably, to antimony in
the lead, which is sometimes used in refining copper. They are more
easily prevented than remedied.

According to M. Frèrejean, proprietor of the great copper works of
Vienne, in Dauphiny, too low a temperature or too much charcoal, gives
to the metal a cubical structure, or that of divergent rays; in either
of which states it wants tenacity. Too high a temperature, or too rapid
a supply of oxygen, gives it a brick red colour, a radiated
crystallization without lustre, or a very fine grain of indeterminate
form; the last structure being unsuitable for copper that is to be
worked under the hammer or in the rolling-press. The form which
indicates most tenacity is radiated with minute fibres glistening in
mass. Melted copper will sometimes pass successively through these three
states in the space of ten minutes.

[Illustration: 316]

_Fig._ 316. represents a _roasting mound_ of copper pyrites in the Lower
Hartz, near Goslar, where a portion of the sulphur is collected. It is a
vertical section of a truncated quadrangular pyramid. A layer of wooden
billets is arranged at the base of the pyramid in the line _a a_.

C, a wooden chimney which stands in the centre of the mound with a small
pile of charcoal at its bottom, _c_; _d d_ are large lumps of ore
surrounded by smaller pieces; _f f_, are rubbish and earth to form a
covering. A current of air is admitted under the billets by an opening,
in the middle of each of the four sides of the base _a a_, so that two
principal currents of air cross under the vertical axis C of the
truncated pyramid, as indicated in the figure.

The fire is applied through the chimney C; the charcoal at its bottom
_c_, and the pile _a a_ are kindled. The sulphureous ores _d_, _f_, are
raised to such a high temperature as to expel the sulphur in the state
of vapour.

In the Lower Hartz a roasting mound continues burning during four
months. Some days after it is kindled the sulphur begins to exhale, and
is condensed by the air at the upper surface of the pyramid. When this
seems impregnated with it, small basins l l are excavated, in which some
liquid sulphur collects; it is removed from time to time with iron
ladles, and thrown into water, where it solidifies. It is then refined
and cast into roll brimstone.

A similar roasting mound contains, in the Lower Hartz, from 100 to 110
tons of ore and 730 cubic feet of wood. It yields in four months about
one ton and a half of sulphur from copper pyrites. Lead ore is treated
in the same way, but it furnishes less sulphur.

There are usually from 12 to 15 roasting heaps in action at once for
three smelting works of the Lower Hartz. After the first roasting two
heaps are united to form a third, which is calcined anew, but under a
shed; the ores are then stirred up and roasted for the third time,
whence a crude mixture is procured for the smelting-house.

The most favourable seasons for roasting in the open air are spring and
autumn; the best weather is a light wind accompanied with gentle rain.
When the wind or rain obstruct the operation, this inconvenience is
remedied by planks distributed round the upper surface of the truncated
pyramid over the sulphur basins.

_Manufacturing assays of copper._--The first thing is to make such a
sample as will represent the whole mass to be valued; with which view,
fragments must be taken from different spots, mixed, weighed, and ground
together. A portion of this mixture being tried by the blow-pipe, will
show, by the garlic or sulphurous smell of its fumes, whether arsenic,
sulphur, or both, be the mineralizers. In the latter case, which often
occurs, 100 gr. or 1000 gr. of the ore are to be mixed with one half its
weight of saw-dust, then imbued with oil, and heated moderately in a
crucible till all the arsenical fumes be dissipated. The residuum being
cooled and triturated, is to be exposed in a shallow earthen cup to a
slow roasting heat, till the sulphur and charcoal be burned away. What
remains being ground and mixed with half its weight of calcined borax,
one-twelfth its weight of lamp black, next made into a dough with a few
drops of oil, is to be pressed down into a crucible, which is to be
covered with a luted lid, and to be subjected, in a powerful air
furnace, first to a dull red heat, and then to vivid ignition for 20
minutes. On cooling and breaking the crucible, a button of metallic
copper will be obtained. Its colour and malleability indicate pretty
well the quality, as does its weight, the relative value of the ore. It
should be cupelled with lead, to ascertain if it contains silver or
gold. See ASSAY, and SILVER.

If the blow-pipe trial showed no arsenic, the first calcination may be
omitted; and if neither sulphur nor arsenic, a portion of the ground ore
should be dried, and treated directly with borax, lamp black and oil. It
is very common to make a dry assay of copper ores, by one roasting and
one fusion along with 3 parts of black flux; from the weight of the
metallic button the richness of the ore is inferred.

The humid assay is more exact, but it requires more skill and time.

The sulphur and the silica are easily got rid of, by the acids which do
not dissolve them, but only the metallic oxides and the other earths.
These oxides may then be thrown down by their appropriate reagents, the
copper being precipitated in the state of either the black oxide, or
pure metal. 105 parts of black oxide represent 100 of copper. Before
entering upon the complete analysis of an ore, preliminary trials should
be made, to ascertain what are its chief constituents. If it be
sulphuret of copper, or copper pyrites, without silver or lead, 100
grains exactly of its average powder may be weighed out, treated in a
matras with boiling muriatic acid for some time, gradually adding a few
drops of nitric acid, till all action ceases, or till the ore be all
dissolved. The insoluble matter found floating in the liquid contains
most of the sulphur; it may be separated upon a filter, washed, dried,
and weighed; then verified by burning away. The incombustible residuum,
treated by muriatic acid, may leave an insoluble deposit, which is to be
added to the former. To the whole of the filtered solutions carbonate of
potash is to be added; and the resulting precipitate, being washed, and
digested repeatedly in water of ammonia, all its cupric oxide will have
been dissolved, whenever the ammonia is no longer rendered blue.

Caustic potash, boiled with the ammoniacal solution, will separate the
copper in the state of black oxide; which is to be thrown upon a filter,
washed, dried, and weighed. The matter left undissolved by the ammonia,
consists of oxide of iron, with probably a little alumina. The latter
being separated by caustic potash, the iron oxide may be also washed,
dried, and weighed. The powder which originally resisted the muriatic
acid, is silica.

_Assay of copper ores, which contain iron, sulphur, silver, lead, and
antimony._

100 grains of these ores, previously sampled, and pulverized, are to be
boiled with nitric acid, adding fresh portions of it from time to time,
till no more of the matter be dissolved. The whole liquors which have
been successively digested and decanted off, are to be filtered and
treated with common salt, to precipitate the silver in the state of a
chloride.

The nitric acid, by its reaction upon the sulphur, having generated
sulphuric acid, this will combine with the lead oxidized at the same
time, constituting insoluble sulphate of lead, which will remain mixed
with the gangue. Should a little nitrate of lead remain in the liquid,
it may be thrown down by sulphate of soda, after the silver has been
separated. The dilute liquid being concentrated by evaporation, is to be
mixed with ammonia in such excess as to dissolve all the cupric oxide,
while it throws down all the oxide of iron and alumina; which two may be
separated, as usual, by a little caustic potash. The portion of ore
insoluble in the nitric acid, being digested in muriatic acid, every
thing will be dissolved except the sulphur and silica. These being
collected upon a filter, and dried, the sulphur may be burned away,
whereby the proportion of each is determined.

_Ores of the_ oxide _of copper_, are easily analyzed by solution in
nitric acid, the addition of ammonia, to separate the other metals, and
precipitation by potash. The _native carbonate_ is analyzed by calcining
100 grains; when the loss of weight will shew the amount of water and
carbonic acid; then that of the latter may be found, by expelling it
from another 100 grains, by digestion in a given weight of sulphuric
acid. The copper is, finally, obtained in a metallic state by plunging
bars of zinc into the solution of the sulphate.

The _native arseniates of copper_ are analyzed by drying them first at a
moderate heat; after which they are to be dissolved in nitric acid. To
this solution, one of nitrate of lead is to be added, as long as it
occasions a precipitate; the deposit is to be drained upon a filter, and
the clear liquid which passes through, being evaporated nearly to
dryness, is to be digested in hot alcohol, which will dissolve every
thing except a little arseniate of lead. This being added to the
arseniate first obtained, from the weight of the whole, the arsenic
acid, constituting 35 per cent., is directly inferred. The alcoholic
solution being now evaporated to dryness, the residue is to be digested
in water of ammonia, when the cupric oxide will be dissolved, and the
oxide of iron will remain. The copper is procured, in the state of black
oxide, by boiling the filtered ammoniacal solution with the proper
quantity of potash.

_The analysis of muriate of copper_--_atacamite_--is an easy process.
The ore being dissolved in nitric acid, a solution of nitrate silver is
added, and from the weight of the chloride precipitated, the equivalent
amount of muriate or chloride of copper is given; for 100 of chloride of
silver represent 93 of chloride of copper, and 43·8 of its metallic
basis. This calculation may be verified by precipitating the copper of
the muriate from its solution in dilute sulphuric acid, by plates of
zinc.

_The phosphate of copper_ may be analyzed either by solution in nitric
acid, and precipitation by potash; or by precipitating the phosphoric
acid present, by means of acetate of lead. The phosphate of lead thus
obtained, after being washed, is to be decomposed by dilute sulphuric
acid. The insoluble sulphate of lead being washed, dried, and weighed,
indicates by its equivalent the proportion of phosphate of lead, as also
of phosphate of copper; for 100 of sulphate of lead correspond to 92·25
phosphate of lead, and 89·5 phosphate of copper; and this again to 52·7
of the black oxide.

Copper forms the basis of a greater number of important ALLOYS than any
other metal. With zinc it forms Brass in all its varieties; which see.

BRONZE and BELL METAL are alloys of copper and tin. This compound is
prepared in crucibles when only small quantities are required; but in
reverberatory hearths, when statues, bells, or cannons are to be cast.
The metals must be protected as much as possible during their
combination from contact of air by a layer of pounded charcoal,
otherwise two evils would result, waste of the copper by combustion, and
a rapid oxidizement of the tin, so as to change the proportions and
alter the properties of the alloy. The fused materials ought to be well
mixed by stirring, to give uniformity to the compound. See BRONZE.

An alloy of 100 of copper and 4·17 of tin has been proposed by M.
Chaudet for the ready manufacture of _medals_. After melting this alloy
he casts it in moulds made of such bone-ash as is used for cupels. The
medals are afterwards subjected to the action of the coining press, not
for striking them, for the mould furnishes perfect impressions, but for
finishing and polishing them.

By a recent analysis of M. Berthier, the bells of the _pendules_, or
ornamental clocks, made in Paris, are found to be composed, of copper
72·00, tin 26·56, iron 1·44, in 100 parts.

An alloy of 100 of copper and 14 of tin is said by M. Dussaussy to
furnish tools, which hardened and sharpened in the manner of the
ancients, afford an edge nearly equal to that of steel.

Cymbals, gongs, and the _tamtam_ of the Chinese are made of an alloy of
100 of copper with about 25 of tin. To give this compound the sonorous
property in the highest degree it must be subjected to sudden
refrigeration. M. D’Arcet, to whom this discovery is due, recommends to
ignite the piece after it is cast, and to plunge it immediately into
cold water. The sudden cooling gives the particles of the alloy such a
disposition that, with a regulated pressure by skilful hammering, they
may be made to slide over each other, and remain permanently in their
new position. When by this means the instrument has received its
intended form, it is to be heated and allowed to cool slowly in the air.
The particles now take a different arrangement from what they would have
done by sudden refrigeration; for instead of being ductile they possess
such an elasticity, that on being displaced by a slight compression,
they return to their primary position after a series of extremely rapid
vibrations; whence a very powerful sound is emitted. Bronze, bell-metal,
and probably all the other alloys of tin with copper present the same
peculiarities.

The alloy of 100 of copper with from 60 to 33 of tin forms common
_bell-metal_. It is yellowish or whitish gray, brittle, and sonorous,
but not so much so as the preceding. The metal of house-clock bells
contain a little more tin than that of church-bells, and the bell of a
repeater contains a little zinc in addition to the other ingredients.

The bronze-founder should study to obtain a rapid fusion, in order to
avoid the causes of waste indicated above. Reverberatory furnaces have
been long adopted for this operation; and among these, the elliptical
are the best. The furnaces with spheroidal domes are used by the
bell-founders, because their alloy being more fusible, a more moderate
melting heat is required; however, as the rapidity of the process is
always a matter of consequence, they also would find advantage in
employing the elliptical hearths (_see the form of the melting furnace,
as figured under Smelting of copper ores_.) Coal is now universally
preferred for fuel.

The alloy of 100 of copper with 50 of tin, or more exactly of 32 of the
former with 14-1/2 of the latter, constitutes _speculum_ metal, for
making mirrors of reflecting telescopes. This compound is nearly white,
very brittle, and susceptible of a fine polish with a brilliant surface.
The following compound is much esteemed in France for making specula.
Melt 2 parts of pure copper and 1 of grain-tin in separate crucibles,
incorporate thoroughly with a wooden spatula, and then run the metal
into moulds. The lower surface is the one that should be worked into a
mirror.

Mr. Edwards, in the Nautical Almanack for 1787, gave the following
instructions for making speculum metal.

The quality of the copper is to be tried by making a series of alloys
with tin, in the proportion of 100 of the former to 47, to 48, to 49,
and to 50 of the latter metal; whence the proportions of the whitest
compound may be ascertained. Beyond the last proportion, the alloy
begins to lose in brilliancy of fracture, and to take a bluish tint.
Having determined this point, take 32 parts of the copper, melt, and add
one part of brass and as much silver, covering the surface of the
mixture with a little black flux; when the whole is melted, stir with a
wooden rod, and pour in from 15 to 16 parts of melted tin (as indicated
by the preparatory trials), stir the mixture again, and immediately pour
it out into cold water. Then melt again at the lowest heat, adding for
every 16 parts of the compound 1 part of white arsenic, wrapped in
paper, so that it may be thrust down to the bottom of the crucible. Stir
with a wooden rod as long as arsenical fumes rise, and then pour it into
a sand mould. While still red hot, lay the metal in a pot full of very
hot embers, that it may cool very slowly, whereby the danger of its
cracking or flying into splinters is prevented.

Having described the different alloys of copper and tin, I shall now
treat of the method of separating these metals from each other as they
exist in old cannons, damaged bells, &c. The process employed on a very
great scale in France during the Revolution, for obtaining copper from
bells, was contrived by Fourcroy; founded upon the chemical fact that
tin is more fusible and oxidizable than copper.

1. A certain quantity of bell metal was completely oxidized by
calcination in a reverberatory furnace; the oxide was raked out, and
reduced to a fine powder.

2. Into the same furnace a fresh quantity of the same metal was
introduced; it was melted, and there was added to it one half of its
weight of the oxide formed in the first operation. The temperature was
increased, and the mixture well incorporated; at the end of a few hours,
there was obtained on the one hand copper almost pure, which subsided in
a liquid state, and spread itself upon the sole of the hearth, while a
compound of oxide of tin, oxide of copper, with some of the earthy
matters of the furnace collected on the surface of the metallic bath in
a pasty form. These scoriæ were removed with a rake, and as soon as the
surface of the melted copper was laid bare, it was run out. The scoriæ
were levigated, and the particles of metallic copper were obtained after
elutriation. By this process, from 100 pounds of bell metal, about 50
pounds of copper were extracted, containing only one _per cent._ of
foreign matters.

3. The washed scoriæ were mixed with 1/8 their weight of pulverised
charcoal; the mixture was triturated to effect a more intimate
distribution of the charcoal; and it was then put into a reverberatory
hearth, in which, by aid of a high heat, a second reduction was
effected, yielding a fluid alloy consisting of about 60 parts of copper
and 20 of tin; while the surface of the bath got covered with new scoriæ
containing a larger proportion of tin than the first.

4. The alloy of 60 of copper with 40 of tin was next calcined in the
same reverberatory furnace, but with stirring of the mass. The air in
sweeping across the surface of the bath, oxidized the tin more rapidly
than the copper; whence proceeded crusts of oxide that were skimmed off
from time to time. This process was continued till the metallic alloy
was brought to the same standard as bell metal, when it was run out to
be subjected to the same operations as the metal of No. 1.

The layers of oxide successively removed in this way were mixed with
charcoal, and reduced in a _fourneau à manche_, or Scotch lead smelting
furnace.

I shall not prosecute any further the details of this complicated
process of Fourcroy; because it has been superseded by a much better one
contrived by M. Bréant. He employed a much larger quantity of charcoal
to reduce the scoriæ rich in tin; and increased the fusibility by adding
crushed oyster-shells, bottle glass, or even vitrified scoriæ, according
to the nature of the substance to be reduced; and he treated them
directly in a reverberatory furnace.

The metal, thus procured, was very rich in tin. He exposed it in masses
on a sloping hearth of a reverberatory furnace, where, by a heat
regulated according to the proportions of the two metals in the alloy,
he occasioned an eliquation or sweating out of the tin. Metallic drops
were seen to transpire round the alloyed blocks or pigs, and, falling
like rain, flowed down the sloping floor of the furnace; on whose
concave bottom the metal collected, and was ladled out into moulds. When
the alloy, thus treated, contained lead, this metal was found in the
first portions that sweated out. The purest tin next came forth, while
the last portions held more or less copper in solution. By fractioning
the products, therefore, there was procured:

  1. Tin with lead.
  2. Tin nearly pure.
  3. Tin alloyed with a little copper.

A spongy mass remained, exhibiting sometimes beautiful crystallizations;
this mass, commonly too rich in copper to afford tin by liquation, was
treated by oxidizement. In this manner, M. Bréant diminished greatly the
reductions and oxidations; and therefore incurred in a far less degree
the enormous waste of tin, which flies off with the draught of air in
high and long continued heats. He also consumed less fuel as well as
labour, and obtained purer products of known composition, ready to be
applied directly in many arts.

He treated advantageously in this manner more than a million of
kilogrammes (1000 tons) of scoriæ, for every 2 cwts. of which he paid 40
_centimes_ (four-pence), while several million kilogrammes of much
richer scoriæ had been previously sold to other refiners at 5 _centimes_
or one _sous_.

I have said that the ancients made their tools and military weapons of
bronze. Several of these have been analyzed, and the results are
interesting.

An antique sword found in 1799, in the peat moss of the Somme, consisted
of copper 87·47; tin 12·53, in 100 parts.

The bronze springs for the balistæ, according to Philo of Byzantium,
were made of copper 97, tin 3.

Hard and brittle nails afforded by analysis, 92 of copper, and 8 of tin.

Of three antique swords found in the environs of Abbeville, one was
found to consist of 85 of copper to 15 of tin. The nails of the handle
of this sword were flexible; they were composed of copper 95, tin 5.

Another of the swords consisted of 90 of copper and 10 of tin; and the
third, of 96 copper, with 4 tin.

A fragment of an ancient scythe afforded to analysis 92·6 copper, and
7·4 tin.

The process of coating copper with tin, exemplifies the strong affinity
between the two metals. The copper surface to be tinned is first cleared
up with a smooth sandstone; then it is heated and rubbed over with a
little sal ammoniac, till it be perfectly clean and bright: the tin,
along with some pounded rosin, is now placed on the copper, which is
made so hot as to melt the tin, and allow of its being spread over the
surface with a dossil or pad of tow. The layer thus fixed on the copper
is exceedingly thin; Bayen found that a copper pan, 9 inches in diameter
and 3-1/4 inches deep, being weighed immediately before and after
tinning, became only 21 grains heavier. Now as the area tinned,
including the bottom, amounted to 155 square inches, 1 grain of tin had
been spread over nearly 7-1/2 square inches; or only 20 grains over
every square foot.

_Copper and Arsenic_ form a white-coloured alloy, sometimes used for the
scales of thermometers and barometers; for dials, candlesticks, &c. To
form this compound, successive layers of copper clippings and white
arsenic are put into an earthen crucible; which is then covered with sea
salt, closed with a lid, and gradually heated to redness. If 2 parts of
arsenic have been used with 5 of copper, the resulting compound commonly
contains one tenth of its weight of metallic arsenic. It is white,
slightly ductile, denser, and more fusible than copper, and without
action on oxygen at ordinary temperatures; but, at higher heats, it is
decomposed with the exhalation of arsenious acid. The white copper of
the Chinese consists of 40·4 copper; 31·6 nickel; 25·4 zinc; and 2·6
iron. This alloy is nearly silver white; it is very sonorous, well
polished, malleable at common temperatures, and even at a cherry red,
but very brittle at a red-white heat. When heated with contact of air,
it oxidizes, burning with a white flame. Its specific gravity was 8·432.
When worked with great care, it may be reduced to thin leaves, and to
wires as small as a needle. See GERMAN SILVER, _infra_.

Tutenag, formerly confounded with white copper, is a different
composition from the above. Keir says it is composed of copper, zinc,
and iron; and Dick describes it as a short metal, of a grayish colour,
and scarcely sonorous. The Chinese export it, in large quantities, to
India.

COPPER, WHITE, or _German silver_. M. Gersdorf, of Vienna, states, that
the proportions of the metals in this alloy should vary according to the
uses for which it is destined. When intended as a substitute for silver,
it should be composed of 25 parts of nickel, 25 of zinc, and 50 of
copper. An alloy better adapted for rolling, consists of 25 of nickel,
20 of zinc, and 60 of copper. Castings, such as candlesticks, bells,
&c., may be made of an alloy, consisting of 20 of nickel, 20 of zinc,
and 60 of copper; to which 3 of lead are added. The addition of 2 or
2-1/2 of iron (in the shape of tin plate?) renders the packfong much
whiter but, at the same time, harder and more brittle.

Keferstein has given the following analysis of the genuine German
silver, as made from the original ore found in Hildburghausen, near
Suhl, in Henneberg:--

  Copper     40·4
  Nickel     31·6
  Zinc       25·4
  Iron        2·6
            -----
            100·0

Chinese packfong, according to the same authority, consists of 5 parts
of copper, alloyed with 7 parts of nickel, and 7 parts of zinc.

The best alloy for making plummer blocks, bushes, and steps for the
steel or iron gudgeons, and pivots of machinery to run in, is said to
consist of 90 parts of copper, 5 of zinc, and 5 of antimony.

A factitious protoxide of copper, of a fine red colour, may be made by
melting together, with a gentle heat, 100 parts of sulphate of copper,
and 59 of carbonate of soda in crystals, and continuing the heat till
the mass become solid. This being pulverized, and mixed exactly with 15
parts of copper filings, the mixture is to be heated to whiteness, in a
crucible, during the space of 20 minutes. The mass, when cold, is to be
reduced to powder, and washed. A beautiful metallic pigment may be thus
prepared, at the cost of 2_s._ a pound.

All the oxides and salts of copper are poisonous; they are best
counteracted by administering a large quantity of sugar, and
sulphuretted hydrogen water.

The following scientific summary of copper ores in alphabetical order
may prove acceptable to many readers, amid the present perplexing
distribution of the native metallic compounds in mineralogical systems.

1. _Arseniate of Copper._

A. _Erinite_, rhomboidal arseniate of copper, micaceous copper,
_kupferglimmer_. Emerald green; specific gravity 4·043; scratches
calc-spar; yields water by heat; fusible at the blowpipe, and reducible
into a white metallic globule. Soluble in nitric acid; the solution
throws down copper by iron. It consists of arsenic acid 33·78; oxide of
copper 59·24; water 5; alumina 1·77. It is found in Cornwall, Ireland,
Hungary.

B. _Liroconite_; octahedral arseniate of copper; lens ore, so called
from the flatness of the crystal. Blue; specific gravity 2·88;
scratches calc-spar. It consists of arsenic acid 14; oxide of copper 49;
water 35. It is found in Huel-Mutrel, Huel-Gorland, Huel-Unity, mines in
Cornwall.

C. _Olivenite_; right prismatic arseniate of copper; olive-ore. Dull
green; specific gravity 4·28; scratches fluor; yields no water by heat;
fusible at the blowpipe into a glassy bead, enclosing a white metallic
grain. It consists of arsenic acid 45, oxide of copper 50·62. It affords
indications of phosphoric acid, which the analysts seem to have
overlooked. It occurs in the above and many other mines in Cornwall.

D. _Aphanese._ Trihedral arseniate of copper. Bluish green, becoming
gray upon the surface; specific gravity 4·28; scarcely scratches
calc-spar; yields water with heat; and traces of phosphoric acid.

The fibrous varieties called wood copper, contain water, and resemble
the last species in composition.

2. _Carbonate of Copper._

A. _Azurite_; kupferlazur. Blue. Crystallizes in oblique rhomboidal
prisms; specific gravity 3 to 3·83; scratches calc-spar, is scratched by
fluor; yields water with heat, and blackens. Its constituents are,
carbonic acid 25·5; oxide of copper 69·1; water 5·4. The Chessy and
Banat azurite is most profitably employed to make sulphate of copper.

B. _Malachite_; green carbonate or mountain green. Crystallizes in right
rhomboidal prisms; specific gravity 3·5; affords water with heat, and
blackens. It consists of carbonic acid 18·5; oxide of copper 72·2; water
9·3.

C. _Mysorine_; anhydrous carbonate of copper. Dark brown generally
stained green or red; conchoidal fracture; soft, sectile; specific
gravity 2·62. It consists of carbonic acid 16·7; oxide of copper 60·75;
peroxide of iron 19·5; silica 2·10. This is a rare mineral found in the
Mysore.

3. _Chromate of Copper and Lead_; vauquelinite. Green of various shades;
specific gravity 6·8 to 7·2; brittle; scratched by fluor; fusible at the
blowpipe with froth and the production of a leaden bead. It consists of
chromic acid 28·33; oxide of lead 60·87; oxide of copper 10·8. It occurs
at Berezof in Siberia along with chromate of lead.

4. _Dioptase_; silicate of copper; emerald copper. Specific gravity 3·3;
scratches glass with difficulty; affords water with heat, and blackens;
infusible at the blowpipe. It consists of silica 43·18; oxide of copper
45·46; water 11·36. This rare substance comes from the government of
Kirgis.

The silicate of Dillenberg is similar in composition.

5. Gray copper ore called Panabase, from the number of metallic bases
which it contains; and Fahlerz. Steel gray; specific gravity 4·79 to
5·10; crystallizes in regular tetrahedrons; fusible at the blowpipe,
with disengagement of fumes of antimony and occasionally of arsenic;
swells up and scorifies, affording copper with soda flux. Is acted upon
by nitric acid with precipitation of antimony; becomes blue with
ammonia; yields a blue precipitate with ferrocyanide of potassium; as
also indications frequently of zinc, mercury, silver, &c. Its
composition which is very complex is as follows: sulphur 26·83; antimony
12·46; arsenic 10·19; copper 40·60; iron 4·66; zinc 3·69; silver 0·60.
Some specimens contain from 5 to 31 per cent. of silver. The gray copper
ores are very common; in Saxony; the Hartz; Cornwall; at Dillenberg; in
Mexico; Peru, &c. They are important on account both of their copper and
silver. _Tennantite_ is a variety of Fahlerz. It occurs in Cornwall. Its
constituents are, sulphur 28·74; arsenic 11·84; copper 45·32; iron 9·26.

6. _Hydrated silicate of Copper_; or Chrysocolla. Green or bluish green;
specific gravity 2·03 to 2·16; scratched by steel; very brittle; affords
water with heat, and blackens; is acted upon by acids, and leaves a
siliceous residuum. Solution becomes blue with ammonia. Its constituents
are silica 26; oxide of copper 50; water 17; carbonic acid 7.

7. _Muriate of Copper._ Atakamite; green; crystallizes in prisms;
specific gravity 4·43. Its constituents are, chlorine 15·90; copper
14·22; oxide of copper 54·22; water 14·16; oxide of iron 1·50. The green
sand of Peru, collected by the inhabitants of Atakama, is this substance
in a decomposed state.

8. _Oxide of Copper._

A. Black, or Melaconise; a black earthy looking substance found at
Chessy and other places. It is deutoxide of copper.

B. Protoxide or red oxide of copper; ziegelerz. Crystallizes in the
regular octahedron; specific gravity 5·69; scratches calc-spar; fusible
at the blowpipe into the black oxide; and reducible in the smoke of the
flame to copper; acted upon by nitric acid with disengagement of nitrous
gas; solution is rendered blue by ammonia. Its constituents are oxygen
11·22; copper 88·78. It occurs near Chessy, and upon the eastern slope
of the Altai mountains.

9. _Phosphate of Copper._ Dark green; crystallizes in octahedrons;
specific gravity 3·6 to 3·8; scratches calc-spar; yields water with
heat; and affords metallic copper with soda flux; acted on by nitric
acid. Its constituents are, phosphoric acid 28·7; oxide of copper 63·9;
water 7·4. It occurs at the mines of Libethen in Hungary.

10. _Pyritous Copper_; Kupferkies; a metallic looking substance, of a
bronze-yellow colour, crystallizing in octahedrons which pass into
tetrahedrons; specific gravity 4·16; fusible at the blowpipe into beads
attractable by the magnet, and which afterwards afford copper with a
soda flux; soluble in nitric acid; solution is rendered blue by ammonia,
and affords an abundant precipitate of iron. Its composition is, sulphur
36; copper 34·5; iron 30·5; being a combined sulphuret of these two
metals. This is the most important metallurgic species of copper ores.
It occurs chiefly in primitive formations, as among gneiss and mica
slate, in veins or more frequently masses in very many parts of the
world--Cornwall, Anglesea, Wicklow, &c. It is found among the early
secondary rocks, in Shetland, Yorkshire, Mansfeldt, &c. The finest
crystallized specimens come from Cornwall, Derbyshire, Freyberg, and
Saint Marie-aux-Mines in France.

11. _Seleniate of Copper_; Berzeline. Is of metallic aspect; silver
white; ductile; fusible at the blowpipe into a gray bead, somewhat
malleable; is acted upon by nitric acid; consists of selenium 40; copper
64.

12. _Sulphate of Copper_; Cyanose. Blue; soluble, &c. like the
artificial sulphates, which see.

_Brochantite_ is a subsulphate of copper observed in small crystals at
Ekaterinenbourg in Siberia.

13. _Sulphuret of Copper_; Kupferglanz. Of a steel gray metallic aspect;
crystallizes in rhomboids; specific gravity 5·69; somewhat sectile, yet
brittle; fusible with intumescence at the blowpipe, and yields a copper
bead with soda; soluble in nitric acid; becomes blue with ammonia, but
lets fall scarcely any oxide of iron. Its constituents are, sulphur 19;
copper 79·5; iron 0·75; silica 1·00. It occurs in small quantities in
Cornwall, &c.

The chemical preparations of copper which constitute distinct
manufactures are, Blue or Roman vitriol; for which see _Sulphate of
Copper_; Scheele’s green and Schweinurth green, Verditer, and Verdigris.
See these articles in their alphabetical places.


COPPER, _Statistics of_.--Copper ores may be imported into Great Britain
for smelting, from any country, and under any flag. On arrival of the
cargo at Swansea or elsewhere, a bond is given at the Custom-house,
which binds the party to return the quantity of copper which the lot of
ores shall be ascertained to contain, into bond within a limited period,
or pay thereon the duty as foreign copper, which is 27_l._ per ton. The
cargo of ore is then weighed out by the custom-house officer, and
samples are taken which are sent to two assay-masters in Cornwall, the
highest produce of the two being entered as that of the cargo. This
fixes the quantity of copper that must be exported under the bond.

The copper produced from foreign ores must then find a market, as cake
or pig copper, in France, Holland, Germany, Italy, the United States of
America, &c. At Calcutta, it is subject to a duty of 6 per cent.; and at
Bombay, to a duty of 10 per cent. _ad valorem_.

The export of British unwrought copper to the continent of Europe, and
to the United States of America, was formerly inconsiderable. These
countries drew the bulk of their supplies either from the north of
Europe, or direct from South America in pig copper. In point of fact,
the copper derived from the import of foreign ores for smelting, has
produced for itself a new market, as the following table, taken from the
official returns will show.

Export of unwrought copper from Great Britain to all parts, except
Asia:--

  Years ending Jan. 5th. 1830   881 tons.
         --              1831   857  --
         --              1832  1326  --
         --              1833  2471  --
         --              1834  2523  --
         --              1835  3267  --
         --              1836  4083  --
         --              1837  2546  --

In the last year, that ended with 5th January, 1838, the export of
unwrought copper was about 5000 tons.

Let any candid and practical man consider attentively this table, and
compare it with the import of foreign ores for the same period, and with
the gradual advance in the value of copper; and then let him, if he can,
avoid the conclusion that the admission of foreign ores for smelting was
a great boon conferred upon the British copper mines, for it made this
country what it now is, the regulator and distributor of the copper
produce of the world--the country to which all others consuming and not
producing copper, must look for a regular, certain, and economical
supply. We want the admission merely under proper and safe regulations,
of foreign copper for refining, to draw to this country the whole
supply of copper for the world, by which prices would be regulated and
maintained, and our copper-mining interests put beyond the reach of
successful rivalry.

This country did not furnish any supply of unwrought copper to the
continent of Europe, or to the United States of America, which was
worthy of notice, before the year 1830; in fact, previous to that time,
we imported considerable quantities of foreign copper for re-exportation
to India. It is easy to explain how the produce of foreign ores, being
prohibited from export in any other shape, has, in fact, opened for
itself a new _debouché_, and this is illustrated by the table, showing
the growth of the export of unwrought copper from 1830. To prove that
this is not merely a simultaneous advance in the export of all sorts of
copper, a corrected table is subjoined from the official returns,
comprising the whole export, and divided so as to illustrate the
operation of the copper produce of foreign ores upon our foreign copper
trade.

Copper exported:--

  +-----------------+--------+----------------+----------+
  |                 |Wrought.|  Unwrought.    |  Total.  |
  |   Years ending  +--------+-------+--------+----------+
  |                 | To all |  To   | To all |  To all  |
  |                 | parts. |India. | parts. |  parts.  |
  +-----------------+--------+-------+--------+----------+
  |                 |_Tons._ |_Tons._|_Tons._ | _Tons._  |
  |5th January, 1825|        |       |  960   |          |
  |             1826|        |       |     1/2|          |
  |             1827|        |       |  130   |          |
  |             1828|        |       | 1329   |          |
  |             1829|        |       | 1079   |          |
  |             1830|  5327  | 1801  | 2682   | 8,009    |
  |             1831|  6172  | 2317  | 3150   | 9,322    |
  |             1832|  5171  | 2423  | 3714   | 8,885    |
  |             1833|  5855  | 2312  | 4569   |10,424    |
  |             1834|  5417  | 1769  | 4019   | 9,436    |
  |             1835|  4787  | 2104  | 5283   |10,072    |
  |             1836|  5948  | 1993  | 5935   |11,883    |
  |             1837|  6105  | 1588  | 3909   |10,014[17]|
  +-----------------+--------+-------+--------+----------+

  [17] Supplement to the Mining Journal, Feb. 28. 1838.

Production of Copper in Great Britain:--

  +---------+-------+----------+
  |  Years. | Ores. |  Metal.  |
  +---------+-------+----------+
  |         |_Tons._| _Tons._  |
  |1771-1781| 28,185|  3380    |
  |1781-1791| 32,854|  4123    |
  |1791-1801| 48,034|  4083    |
  |1801-1811| 67,533|  6060    |
  |1811-1816| 78,237|  7181    |
  |  1816   | 83,058|  7045    |
  |  1817   | 75,016|  6608    |
  |  1818   | 80,525|  6714    |
  |  1819   | 92,234|  7214    |
  |  1820   | 92,672|  7364    |
  |  1821   | 98,803|  8163    |
  |  1822   |106,723|  9331    |
  |  1826   |128,459|   --     |
  |  1827   |   --  |12,381    |
  |  1828   |153,600|12,169    |
  |  1829   |   --  |11,994    |
  |  1830   |   --  |13,097    |
  |  1831   |   --  |14,480    |
  |  1832   |   --  |14,463[18]|
  +---------+-------+----------+

  [18] Taylor’s Records of Mining, Part I., p. 171.

Quantity of Copper produced in the several districts of Great Britain
and Ireland:--

  +----------------------+--------+--------+--------+--------+--------+
  |With Ores from--      |  1828. |  1829. |  1830. |  1831. |  1832. |
  +----------------------+--------+--------+--------+--------+--------+
  |                      | _Tons._| _Tons._| _Tons._| _Tons._| _Tons._|
  |Cornwall              |   1966 |   9763 | 10,890 | 12,218 | 12,099 |
  |Devonshire            |    434 |    318 |    368 |    312 |    249 |
  |Other parts of England|     71 |     36 |     10 |     31 |     42 |
  |Island of Anglesea    |    738 |    901 |    815 |    809 |    852 |
  |Other parts of Wales  |    259 |    172 |    237 |    123 |    237 |
  |Ireland               |    706 |    790 |    768 |    972 |    974 |
  |Isle of Man           |    --  |      4 |      9 |     15 |     12 |
  |                      | ------ | ------ | ------ | ------ | ------ |
  |Total copper from the | 12,169 | 11,994 | 13,097 | 14,480 | 14,465 |
  |ores of the United    |        |        |        |        |        |
  |Kingdom               |        |        |        |        |        |
  |Copper smelted from   |   --   |     30 |    124 |    100 |     56 |
  |Foreign ores          |        |        |        |        |        |
  |                      | ------ | ------ | ------ | ------ | ------ |
  |General total         | 12,169 | 12,024 | 13,221 | 14,580 | 14,521 |
  +----------------------+--------+--------+--------+--------+--------+

_Statistics of Copper for Cornwall in 1837._--The total quantity of ore
sold was 142,089 tons (of 21 cwts.), yielding an average produce of
eight per cent.; the quantity of fine copper being 11,209 tons 1 cwt.;
and the average price of the ore 5_l._ 15_s._ 6_d._; the total amount of
the sales for the twelve months being 822,516_l._ The standard upon the
5th of January was 127_l._ 16_s._; this was the highest for the year.
Upon the 22d of June it was at the lowest, being only 93_l._ 18_s._ It
went up again to 120_l._ 10_s._ upon the 5th of October; but declined
with some slight fluctuation to 107_l._ 18_s._ upon the 28th of
December. The largest quantity sold at any one ticketing, was 4670 tons,
upon the 4th of May: and the smallest 1088, upon the 17th of August. The
highest produce was nine and five-eighths per cent. upon the 13th of
July; and the lowest, seven, upon the 26th of January. The greatest
weekly total was 25,887_l._, upon the 2nd of November, and the least
5694_l._ upon the 17th of August. The average sum per week was
15,817_l._[19]

  [19] Mining Review, Feb. 28, 1838.

Table of the produce of Copper Ores and fine Metal in Cornwall, from
1800 to 1830.

  +------+---------+----------+--------------+---------+-----------+
  |Years.|  Ores.  |  Metal.  | Value of Ore.|  Metal. |  Average  |
  |      |         |          |              |         | Standard. |
  +------+---------+----------+--------------+---------+-----------+
  |      |         |          |              |  _Per_  |  _Price_  |
  |      |_Tons of_|_Tons._   |              | _Cent._ | _per Ton._|
  |      |_21 Cwts_|    _Cwt._|  _£    s. d._|_of Ore._| _£  s. d._|
  | 1800 |  55,981 |  5187  0 |550,925  0  0 |  9-1/4  | 133  3  6 |
  | 1801 |  56,611 |  5268  0 |476,313  0  0 |  9-1/4  | 117  8  0 |
  | 1802 |  53,937 |  5228 15 |445,094  0  0 |  9-5/8  | 110 18  0 |
  | 1804 |  64,637 |  5374 18 |507,840 11  0 |  8-3/8  | 136  5  0 |
  | 1806 |  79,269 |  6863 10 |730,845  6  0 |  8-5/8  | 138  5  0 |
  | 1808 |  67,867 |  6795 13 |495,303 10  0 | 10      | 100  7  0 |
  | 1810 |  66,048 |  5682 19 |570,035  8  0 |  8-1/2  | 132  5  0 |
  | 1812 |  71,547 |  6720  7 |549,665  6  0 |  9-3/8  | 111  0  0 |
  | 1814 |  74,322 |  6369 13 |627,501 10  0 |  8-1/2  | 130 12  0 |
  | 1816 |  77,334 |  6697  4 |447,959 17  0 |  8-5/8  |  98 13  0 |
  | 1818 |  86,174 |  6849  7 |686,005  4  0 |  7-7/8  | 134 15  0 |
  | 1820 |  91,473 |  7508  0 |602,441 12  0 |  8-1/8  | 113 15  0 |
  | 1822 | 104,523 |  9140  8 |663,085 13  0 |  8-3/4  | 104  0  0 |
  | 1824 |  99,700 |  7823 15 |587,178  0  0 |  7-7/8  | 110  0  0 |
  | 1826 | 117,308 |  9026 12 |788,971 15  0 |  7-5/8  | 123  3  0 |
  | 1828 | 130,366 |  9921  1 |756,174 16  0 |  7-5/8  | 112  7  0 |
  | 1829 | 124,502 |  9656 10 |717,334  0  0 |  7-3/4  | 109 14  0 |
  | 1830 | 143,296 |11,224 19 |887,900  0  0 |  7-3/4  | 114  4  0 |
  | 1834 |}150,617 |12,271 14 |893,402 15  0 |  8-1/8  | 106 11  0 |
  | 1835 |}        |          |              |         |           |
  +------+---------+----------+--------------+---------+-----------+

Produce of Copper Mines in Cornwall, (on the authority of John Taylor,
Esq. F.R.S.)

  +------+-------+-------+--------------+----------+---------+
  |Years.| Ore.  |Metal. |    Value.    | Produce. |Standard.|
  +------+-------+-------+--------------+----------+---------+
  |      |_Tons._|_Tons._| _£.    s. d._|_Per Cwt._|         |
  | 1831 |144,402|12,044 |806,090 15  6 |  8-1/4   |   100   |
  | 1832 |137,357|11,948 |825,612  6  0 |  8-5/8   |   100   |
  | 1833 |138,300|11,191 |858,708 10  0 |  8-1/8   |   111   |
  | 1834 |143,296|11,226 |887,902  0  0 |  7-3/4   |   114   |
  | 1835 |150,617|12,270 |893,402 14  0 |  8-1/8   |   106   |
  | 1836 |140,981|11,647 |957,752  8  6 |  8-1/4   |   115   |
  | 1837 |140,753|10,832 |908,613 15  0 |  7-5/8   |   120   |
  +------+-------+-------+--------------+----------+---------+

An account of the quantities of Foreign wrought and unwrought Copper,
and Copper Ore imported and exported, and of British wrought and
unwrought Copper exported from the United Kingdom; together with the
quantities and value of Copper Ore smelted in Cornwall and Swansea, and
the quantity of Copper produced in those places; and in the county of
Devon; together with the market prices of sheet and cake Copper, in the
year ending 5th January, 1835.

  +---------------------------------------------+-------+--------------+
  |                                             |Quanti-|    Value.    |
  |                                             |  ty.  |              |
  +---------------------------------------------+-------+--------------+
  |Foreign Copper imported:--                   |       |   _£   s. d._|
  |  Unwrought in bricks or pigs, rose and cast |       |              |
  |  copper                             _Cwts._ |  5,389|              |
  |  Part wrought, viz., bars, rods, or ingots, |       |              |
  |  hammered or raised                         |  1,968|              |
  |  Wrought plates and coin                    |      2|              |
  |    --    old for re-manufacture             |    493|              |
  |  Copper ore Foreign                         |278,900|              |
  |  Manufactures of copper, entered by weight  |    650|              |
  |             --           entered at value   |   --  |  5,353  0  0 |
  |Foreign Copper exported, viz.:--             |       |              |
  |  Unwrought, in bricks and pigs, rose and    |       |              |
  |  cast copper                        _Cwts._ |  6,898|              |
  |  Part wrought, viz., bars, rods, or ingots, |       |              |
  |  hammered or raised                         |  2,013|              |
  |  Old, fit only for re-manufacture           |    265|              |
  |  Smelted in the United Kingdom from foreign |       |              |
  |  ore                                        | 55,456|              |
  |  Manufactures of copper, entered by weight  |    650|              |
  |             --           entered at value   |   --  |    112  0  0 |
  |                                             |       |              |
  |              BRITISH COPPER.                |       |              |
  |Exported, unwrought, in bricks and pigs      |       |              |
  |                                     _Cwts._ | 63,252|              |
  |   --     wrought sheets, nails, &c.         |103,433|              |
  |            --    wire                       |     56|              |
  |            --    of other sorts             | 15,197|              |
  |   --     Total of British copper exported   |182,225|              |
  |Ores sold in Cornwall:--                     |       |              |
  |  Quantity of ore                     _Tons_ |150,617|              |
  |  Value of ditto                             |   --  |893,403  0  0 |
  |  Quantity of metal                   _Tons_ | 12,270|              |
  |  Standard                                   |   --  |    106 11  0 |
  |  Produce per cent.                          |  8-1/2|              |
  |Ores sold, &c. in Swansea:--                 |       |              |
  |  Quantity of ore                     _Tons_ | 28,746|              |
  |  Value of ditto                             |   --  |223,958  0  0 |
  |  Quantity of metal                   _Tons_ |  2,832|              |
  |  Standard                                   |   --  |    101 18  0 |
  |  Produce per cent.                          |  9-7/8|              |
  |Copper sold in Devonshire {  ore  }   _Tons_ |{ 5,114|              |
  |                          { metal }          |{   455|              |
  |Total quantity of copper raised in the     } |       |              |
  |United Kingdom, exclusive of Anglesea and  } |       |              |
  |Staffordshire, and deducting 1083 tons of  } |       |              |
  |metal, value 88,207_l._, the produce of    } |       |              |
  |4985 tons of foreign ore sold at Swansea,  } |-------|              |
  |included above.                            } | 14,474|              |
  +---------------------------------------------+-------+--------------+


COPPERAS. (_Couperose verte_, Fr.; _Eisenvitriol_, Germ.) Sulphate of
iron.


CORAL, (_Corail_, Fr.; _Koralle_, Germ.) is a calcareous substance,
formed by a species of sea polypus, which constructs in concert immense
ramified habitations, consisting of an assemblage of small cells, each
the abode of an animal. The coral is therefore a real polypary, which
resembles a tree stripped of its leaves. It has no roots, but a foot not
unlike a hemispherical skull-cap, which applies closely to every point
of the surface upon which it stands, and is therefore difficult to
detach. It merely serves as a basis or support to the coral, but
contributes in no manner to its growth, like the root of an ordinary
tree; for detached pieces have been often found at the bottom of the sea
in a state of increase and reproduction. From the above base a stem
usually single proceeds, which seldom surpasses an inch in diameter, and
from it a small number of branches ramify in very irregular directions,
which are studded over with cells, each containing an insect. The
polypi, when they extend their arms, feelers, or _tentacula_, resemble
flowers, whence, as well as from the form of the coral, they were
classed among vegetable productions. They are now styled zoophytes by
the writers upon Natural History.

The finest coral is found in the Mediterranean. It is fished for upon
the coasts of Provence, and constitutes a considerable branch of trade
at Marseilles. The coral is attached to the submarine rocks, as a tree
is by its roots, but the branches, instead of growing upwards, shoot
downwards towards the bottom of the sea; a conformation favourable to
breaking them off and bringing them up. For this kind of fishing, eight
men, who are excellent divers, equip a felucca or small boat, called
commonly a coralline. They carry with them a large wooden cross, with
strong, equal, and long arms, each bearing a stout bag-net. They attach
a strong rope to the middle of the cross, and let it down horizontally
into the sea, having loaded its centre with a weight sufficient to sink
it. The diver follows the cross, pushes one arm of it after another into
the hollows of the rocks, so as to entangle the coral in the nets. Then
his comrades in the boat pull up the cross and its accompaniments.

Coral fishing is nearly as dangerous as pearl fishing, on account of the
number of sharks which frequent the seas where it is carried on. One
would think the diving-bell in its now very practicable state might be
employed with great advantage for both purposes.

Coral is mostly of a fine red colour, but occasionally it is
flesh-coloured, yellow, or white. The red is preferred for making
necklaces, crosses, and other female ornaments. It is worked up like
precious stones. See LAPIDARY.


CORK, (_Liége_, Fr.; _Kork_, Germ.) is the bark of the _quercus liber_,
Linn., a species of oak-tree, which grows abundantly in the southern
provinces of France, Italy, and Spain. The bark is taken off by making
coronal incisions above and below the portions to be removed; vertical
incisions are then made from one of these circles to another, whereby
the bark may be easily detached. It is steeped in water to soften it, in
order to be flattened by pressure under heavy stones, and next dried at
a fire which blackens its surface. The cakes are bound up in bales and
sent into the market.

There are two sorts of cork, the white and the black; the former grows
in France and the latter in Spain. The cakes of the white are usually
more beautiful, more smooth, lighter, freer from knots and cracks, of a
finer grain, of a yellowish gray colour on both sides, and cut more
smoothly than the black. When this cork is burned in close vessels it
forms the pigment called _Spanish black_.

This substance is employed to fabricate not only bottle corks, but small
architectural and geognostic models, which are very convenient from
their lightness and solidity.

The cork-cutters divide the boards of cork first into narrow fillets,
which they afterwards subdivide into short parallelopipeds, and then
round these into the proper conical or cylindrical shape. The bench
before which they work is a square table, where 4 workmen are seated,
one at every side, the table being furnished with a ledge to prevent the
corks from falling over. The cork-cutter’s knife is a broad blade, very
thin, and fine edged. It is whetted from time to time upon a
fine-grained dry whetstone. The workman ought not to draw his knife edge
over the cork, for he would thus make misses, and might cut himself, but
rather the cork over the knife edge. He should seize the knife with his
left hand, rest the back of it upon the edge of the table; into one of
the notches made to prevent it from slipping, and merely turns its edge
sometimes upright and sometimes to one side. Then holding the squared
piece of cork by its two ends, between his finger and his thumb, he
presents it in the direction of its length to the edge; the cork is now
smoothly cut into a rounded form by being dexterously turned in the
hand. He next cuts off the two ends, when the cork is finished and
thrown into the proper basket alongside, to be afterwards sorted by
women or boys.

Of late years a much thicker kind of cork boards have been imported from
Catalonia, from which longer and better corks may be made. In the art of
cork-cutting the French surpass the English, as any one may convince
himself by comparing the corks of their champagne bottles with those
made in this country.

Cork, on account of its buoyancy in water, is extensively employed for
making floats to fishermen’s nets, and in the construction of
life-boats. Its impermeability to water has led to its employment for
inner soles to shoes.

When cork is rasped into powder, and subjected to chemical solvents,
such as alcohol, &c., it leaves 70 per cent. of an insoluble substance,
called _suberine_. When it is treated with nitric acid, it yields the
following remarkable products:--White fibrous matter 0·18, resin 14·72,
oxalic acid 16·00, suberic acid (peculiar acid of cork) 14·4 in 100
parts.

_Machine cork-cutting._--A patent was obtained some years ago by Sarah
Thomson for this purpose. The cutting of the cork into slips is effected
by fixing it upon the sliding bed of an engine, and bringing it, by a
progressive motion, under the action of a circular knife, by which it is
cut into slips of equal widths. The nature or construction of a machine
to be used for this purpose may be easily conceived, as it possesses no
new mechanical feature, except in its application to cutting cork. The
motion communicated to the knife by hand, steam, horse, or other power,
moves at the same time the bed also, which carries the cork to be cut.

The second part of the invention, viz. that for separating the cork into
square pieces, after it has been cut in slips as above, is effected by a
moving bed as before, upon which the slips are to be placed and
submitted to the action of a cutting lever, which may be regulated to
chop the cork into pieces of any given length.

The third part of the invention, viz., that for rounding or finishing
the corks, consists of an engine to which is attached a circular knife
that turns vertically, and a carriage or frame upon its side that
revolves upon an axle horizontally.

This carriage or frame contains several pairs of clamps, intended
respectively to hold a piece of the square cut cork by pressing it at
the ends, and carrying it lengthways perpendicularly; which clamps are
contrived to have a spindle motion, by means of a pinion at the lower
end of their axles, working into a spur-wheel.

The machinery, thus arranged, is put in motion by means of bands and
drum-wheels, or any other contrivance which may be found most eligible;
and at the same time that the circular knife revolves vertically, the
frame containing the clamps with the pieces of cork, turns horizontally,
bringing the corks, one by one, up to the edge of the knife, when, to
render each piece of cork cylindrical, the clamps, as above described,
revolve upon their axes, independently of their carriage, by which means
the whole circumference of the cork is brought under the action of the
knife, the superfluous parts are uniformly pared off, and the cork
finished smooth and cylindrical.


CORROSIVE SUBLIMATE; bichloride of mercury.


CORUNDUM; or _Telesie_; a very hard genus of aluminous minerals, to
which the gems, sapphire, ruby, salamstein, and adamantine spar belong.


COTTON DYEING. (_Teinture de Coton_, Fr.; _Baumwollenfärberei_, Germ.)
Cotton and linen yarns and cloths have nearly the same affinity for
dyes, and may therefore with propriety be treated, in this respect,
together. After they have acquired the proper degree of whiteness (see
BLEACHING) they are still unfit to receive and retain the dyes in a
permanent manner. It is necessary, before dipping them into the
dye-bath, to give them a tendency to condense the colouring particles
within their cavities or pores, and to communicate such chemical
properties as will fix these particles so that they will not separate,
to whatever ordinary trial they may be subjected. All the colours which
it would be desirable to transfer to these stuffs unfortunately do not
possess this permanence. Men of science engaged in this important art
have constantly aimed at the discovery of some new processes which may
transfer into the class of fast colours those dyes which are at present
more or less fugitive. Almost all the goods manufactured of cotton,
flax, or hemp, are intended to be washed, and ought, therefore, to be so
dyed as to resist the alkaline and soapy solutions commonly used in the
laundry. Vitalis distinguished dyed cottons into three classes; 1. the
_fugitive_, or fancy-coloured (_petit teint_), which change their hue or
are destroyed by one or two boils with soap; 2. those which resist five
or six careful washings with soap, are _good_ dyes, (_bon teint_); and
those which were still more durable, such as Turkey reds, may be called
_fast_ colours (_grand teint_). The colours of Brazil wood, logwood,
annotto, safflower, &c., are _fugitive_; those made with madder without
an oily base, are _good_; and those of madder with an oily mordant, are
_fast_. It is, however, possible to point out certain processes for
giving these different orders of dyes a greater degree of fixity.

I shall describe, in the five following paragraphs, the operations
conducive to the fixation of colours upon cotton and linen.

1. _Galling._ Either gall nuts alone, or sumach alone, or these two
substances united, are employed to give to cotton the fast dye
preparation. 2 or 3 ounces of galls for every pound of cotton, being
coarsely pounded, are to be put into a copper containing about 30
gallons of water for every 100 pounds of cotton, and the bath is to be
boiled till the bits of galls feel pasty between the fingers. The fire
being withdrawn, when the bath becomes moderately cool, it is passed
through a hair-cloth sieve. If during this operation the liquor should
become cold, it must be made once more as hot as the hand can bear. A
portion of it is now transferred into another vessel, called a _back_,
in which the cotton is worked till it be well penetrated with the
decoction. It is then taken out, wrung at the peg or squeezed in a
press, and straightway hung up in the drying house. Some more of the
fresh decoction being added to the partially exhausted liquor in the
back, the process is resumed upon fresh goods.

The manipulation is the same with sumach, but the bath is somewhat
differently made; because the quantity of sumach must be double that of
galls, and must be merely infused in very hot water, without boiling.
When galls and sumach are both prescribed, their baths should be
separately made and mixed together.

2. _Aluming._ Alum is a salt which serves to prepare cotton for
receiving an indefinite variety of dyes. Its bath is made as follows:
For 100 pounds of scoured cotton, about 30 gallons of water being put
into the copper, are heated to about 122° F., when 4 ounces of alum,
coarsely pounded, are thrown in for every pound of cotton, and instantly
dissolved. Whenever the heat of the bath has fallen to about 98° F., the
cotton is well worked in it, in order that the solution may thoroughly
penetrate all its pores. It is then taken out, wrung at the peg or
squeezed in the press, and dried in the shade. The solution of alum is
of such constant employment in this kind of dyeing, that it should be
made in large quantities at a time, kept in the alum tun, where it can
suffer no deterioration, and drawn off by a spigot or stop-cock as
wanted.

There are certain colours which require alum to be deprived of a portion
of its acid excess, as a supersalt; which may be done by putting 1 ounce
of crystals of soda into the tun for every pound of alum. But so much
soda should never be used as to cause any permanent precipitation of
alumina. When thus prepared, it is called _saturated alum_, though it is
by no means neutral to litmus paper; but it crystallizes differently
from ordinary alum.

Cotton does not take up at the first aluming a sufficient quantity of
alum; but it must receive a second, or even a third immersion. In every
case the stuff should be thoroughly dried, with an interval of one or
two days between each application; and it may even be left for 10 or 12
hours moist with the alum bath before being hung in the air. When the
cotton is finally dry, it must be washed before being plunged into the
dye bath; otherwise, the portion of alum, not intimately combined with
the cotton, but adhering externally to its filaments, would come off by
the heat, mix with the bath, alter the colour by dissolving in it, and
throw it down to the bottom of the copper, in the form of a lake, to the
great loss of the dyer. Madder reds, weld yellows, and some other
colours, are more brilliant and faster when acetate of alumina, prepared
with acetate of lead, alum, and a little potash, is used, than even
saturated alum. This mordant is employed cold, and at 4° Baumé.

3. _Mordants._ See this article in its alphabetical place.

4. _Dye baths_, are distinguished into two classes; the colouring bath,
and the dyeing bath. The former serves to extract the colouring matters
of the different substances, with the exception of madder, which is
always used in substance, and never as an extract, infusion, or
decoction. In all these cases, when the colour is extracted, that is,
when the dye bath is completed by the degree of heat suited to each
substance, it is then allowed to cool down a certain way, and the cotton
is worked or winced through it, to get the wished-for tint. This is what
is called the dye bath. Several colouring baths are made in the cold;
and they serve to dye also in the cold; but the greater part require a
heat of 90° or 100° to facilitate the penetration of the stuffs by the
colouring particles. The description of the several dye baths is given
under the individual dyes.

5. _Of the washing after the dyeing._--The washing of the cottons after
they have received the dyes, is one of the most important operations in
the business. If it is not carefully performed, the excess of colour not
combined with the fibres, is apt to stain whatever it touches. This
inconvenience would be of little consequence, if the friction carried
off the colour equally from all the points; but it does not do so, and
hence the surface appears mottled. A well-planned dye house should be an
oblong gallery, with a stream of water flowing along in an open conduit
in the middle line, a series of dash wheels arranged against the wall,
at one side, and of dyeing coppers, furnished with self-acting winces or
reels, against the other. In such a gallery, the washing may be done
either by hand, by the rinsing machine, or by the dash wheel, according
to the quality of the dye, and the texture of the stuffs. And they may
be stripped of the water either by the jack and pin, by the squeezing
roller, or by the press. Wooden pins are placed in some dye-houses on
each side of the wash cistern or pool. They are somewhat conical, 1-1/2
foot high, 3-1/2 inches in diameter at the base, 1-1/2 at the top, are
fixed firmly upright, and at a level of about 3 feet above the bottom of
the cistern, so as to be handy for the workmen. See BRAZIL WOOD, FUSTIC,
MADDER, BLACK DYE, BROWN DYE, &c., as also BLEACHING, BRAN, CALICO
PRINTING, DUNGING, DYEING, &c.


COTTON MANUFACTURE. (_Filature de Coton_, Fr.; _Baumwollespinnerei_,
Germ.) Cotton is a filamentous down, which invests the seeds of the
plant called _gossypium_ by Linnæus, and placed by him in the class
_monadelphia_ and order _monandria_, but belonging to the natural family
of _malvaceæ_. It has a cup-shaped calyx, obtusely five-toothed,
inclosed in a three-cleft exterior calyx; the leaflets are united at
their base, of a heart shape and toothed; stigmas three to five; capsule
three to five celled and many-seeded; seeds bearing a downy wool.
Thirteen species are described by Decandolle, but their characters are
very uncertain, and no botanist can assign to a definite species of the
plant, the very dissimilar staples of the cotton filaments found in
commerce. The leaves are generally palmate and hairy; and the blossoms
are large, and of a beautiful yellow. The _gossypium religiosum_ of
Tranquebar has white blossoms in some of its varieties, to which,
probably, the white cotton of Rome, cultivated in the Jardin des Plantes
at Paris, belongs. The filaments differ in length, flexibility,
tenacity, and thickness, in different cottons, whence the great
differences of their value to the cotton-spinner, as the prices current
in the market show. Thus, at Liverpool, on the 1st of December, 1835,
the following values were assigned to the following cottons:--

                      _s._  _d._     _s._ _d._
  Sea-island            1   6     to   2   6
  Demerara and Berbice  0   9          1   0
  Pernambuco            0  10-3/4      1   1-1/2
  Egyptian              0  11-1/2      1   2-1/2
  New Orleans           0   7-1/8      1   0
  Bahia                 0   8-1/4      0  10
  Upland Georgia        0   7-1/8      0  11-1/2
  West Indian           0   7-3/4      0   9
  Surat                 0   6-1/8      0   8
  Madras                0   6-1/2      0   8
  Bengal                0   5-1/4      0   6-1/2

But it is to be observed, that there are varieties of the Sea-island
Georgian cotton, so highly prized by the spinner of fine yarn, as to
fetch 3_s._, 4_s._, or even 5_s._ per pound.

The filaments of cotton, when examined with a good microscope, are seen
to be more or less ribbon-like, and twisted; having a breadth varying
from 1/800 of an inch in the strongest Smyrna or candle-wick cotton of
the Levant, to 1/2500 of an inch in the finest Sea-island.

The main distinction between cottons in the pod, is that of the black
seeded, and the green seeded; for the former part with their downy wool
very readily to a pair of simple rollers, made to revolve nearly in
contact, by the power of the human arm; while the latter retain the wool
with much force, and require to be ginned, as the operation is called,
by a powerful revolving circular saw-mechanism, usually driven by horse
or water power. After the cotton wool is thus separated from the seeds,
it is packed in large canvas bags, commonly with the aid of a screw or
hydraulic press, into a very dense bale, for the convenience of
transport. Each of the American bags contains about 340 lbs. of cotton
wool. When this cotton is delivered to the manufacturer, it is so foul
and flocky, that he must clean and disentangle it with the utmost care,
before he can subject it to the carding operation.

[Illustration: 317]

_Fig._ 317. A B, is a roller, about 9 inches in diameter, which revolves
in the direction of the arrow. This cylinder consists of a parallel
series of oblique pointed circular saws made fast to one axis, and
parted from each other by wooden rings nearly one inch and a half in
thickness. Above the cylinder is a kind of hopper E F, into which ginner
throws the seed cotton, which falls upon a grating, up though which
small segments of the saw-teeth project, so as to lay hold of the fibres
in their revolution, and pull them through, while the seeds being thus
separated, roll down the slope of the grid, to be discharged from the
spout I K. M is a cylindrical brush placed below the grating, which
revolves against the saw teeth, so as to clear them of the adhering
cotton filaments.

The _willow_, which was originally a cylindrical willow basket, whence
its name, but is now a box made of wood, with revolving iron spikes, is
the first apparatus to which cotton wool is exposed, after it has been
opened up, picked, and sorted by hand or a rake, in what is called a
_bing_. The willow exercises a winnowing action, loosens the large
flocks, and shakes out much of the dirt contained in them. The frame of
the willow is about 2 feet wide, and turns with its spikes at the rapid
rate of 600 revolutions per minute, whereby it tosses the cotton about
with great violence. The heavy impurities fall down through the grid
bottom. It is exposed, however, for only a few minutes to the action of
this machine. For factories which work up chiefly the coarser and fouler
cottons of India, and Upland Georgia, the conical self-acting willow,
as constructed by Mr. Lillie at Manchester, is much employed. In it,
the cotton is put in at the narrow end of the truncated cone, which,
being spiked, and revolving rapidly within a nearly concentric case upon
a horizontal axis, wafts it on towards the wide end, while its
impurities are partly shaken out through the grid or perforated bottom,
and partly sucked up through revolving squirrel wire cages, by the
centrifugal action of a fan. This is a powerful automatic engine,
deserving the study of the curious, and is as safe as it is powerful.
The cone of this huge machine makes from 400 to 600 turns per minute,
and will clean 7200 pounds, or 24 bags, in a day.

After shaking out the grosser impurities by the willow, the cotton
spinner proceeds to separate each individual filament of cotton wool
from its fellow, so as to prepare it for carding, and to free it from
every particle of foreign matter, whether lighter or heavier than
itself. This second operation is performed by what are called batting
(_beating_), scutching, and blowing machines, which are all now much the
same, whatever difference of signification the name may have. Indeed,
each machine not only beats, scutches, but blows. _Fig._ 318. exhibits a
longitudinal section of a good blowing engine of modern construction.
The machine is about 18 or 19 feet long, and three feet across within
the case. The whole frame is made of cast-iron, lined with boards,
forming a close box, which has merely openings for introducing the raw
cotton wool, for taking out the cleansed wool, and removing the dust as
it collects at the bottom. These doors are shut during the operation of
the machine, but may be opened at pleasure, to allow the interior to be
inspected and repaired.

[Illustration: 318]

The introduction of the cotton is effected by means of an endless cloth
or double apron, which moves in the direction of the arrow _a a_, at the
left end of the figure, by passing round the continually revolving
rollers at _b_ and _c_. The two rollers at _e_, being the ones which
immediately introduce the cotton into the jaws, as it were, of the
machine, are called the feed rollers. The batting arm, or revolving
diameter, _f e_, turns in the direction of the arrow, and strikes the
flocks violently as they enter, so as to throw down any heavy particles
upon the iron grating or grid at _n_, while the light cotton filaments
are wafted onwards with the wind, from the rotation of the scutcher in
the direction of arrow _a´_, along the second travelling apron, upon
which the squirrel cage cylinder presses, and applies the cotton in the
form of a lap. Above the cylindric cage _h_, which turns in the
direction of its arrow, there is a pipe _k_, the continuation of the
case _i_. This pipe, though broken off in the figure, communicates by a
branch pipe with an air-sucking fan ventilator, not seen in this figure,
but explained under FOUNDRY. The cage _h_, by its rotation, presses
down, as we have said, the half-cleaned cotton upon the cloth _a´_,
which carries it forward to the second scutcher _f´_, by the second set
of feed rollers _e´_. The second scutcher throws down the heavy dust
upon the second grid _n´_, through which it falls upon the bottom of the
case. The first scutcher makes about 1280 strokes of each of its two
arms in a minute; the second 1300. The feed rollers for each are fluted.
The feed cloth is either sustained by a board, or is made of parallel
spars of wood, to secure it against bagging, which would render the
delivery of the cotton irregular. The feed rollers make 8 turns in the
minute, and as their diameter is 1-1/2 inches, they will introduce 8
times their circumference, or 37·7 inches of the cotton spread upon the
apron in that time. Upon every 12th part of an inch of the cotton,
therefore, nearly 3 blows of the scutcher arm will be applied. The
second feed rollers move relatively with more slowness, so that for
every 2·4 blows of the scutcher, only one twelfth of an inch of cotton
wool is presented.

The fan is inclosed in a cylindrical case. The wings or vanes revolve
from 120 to 150 times in the minute; and while they throw the air out
with nearly this velocity at their excentric outlet in the
circumference, they cause it to enter, with equal velocity, at the
centre. With this centre the squirrel cage is connected by a pipe, as
above stated. The sound filaments of the cotton are arrested by the
sieve surface of the cylindric cage, and nothing but the broken
fragments and the light dust can pass through.

The cotton wool in the blowing machine is wafted by the second scutcher
into the space _x_, _w w_, provided with a fine grid bottom; or it is
sometimes wound up there by rollers into a lap.

In _fig._ 318. an additional ventilator is introduced beneath at _m_, _o
o_, to aid the action of the scutchers in blowing the cotton onwards
into the oblong trough _a_. The outlet of that fan is at _t_; and it
draws in the air at its axis _q_. _u_ and _v_, are two doors or lids for
removing the cleaned cotton wool. This last fan is suppressed in many
blowing machines, as the scutching arms supply a sufficient stream of
air. The dotted lines show how the motion is transmitted from the first
mover at _s_, to the various parts of the machine. 6´ 6´ represent the
bands leading to the main shafting of the mill. A machine of this kind
can clean fully 600 pounds of short-stapled cotton wool in a day, with
the superintendence of one operative, usually a young woman, to
distribute the cotton upon the first feed cloth.

[Illustration: 319]

The second Blowing machine is usually called a _lap_ machine, because,
after blowing and scutching the cotton, as above described, it
eventually coils the fleece upon a wooden roller at the delivering end
of the apparatus. It is sometimes also called a _spreading machine_. A
section of it is shown in _fig._ 319. The breadth of this machine is
about 3 feet as the lap formed is prepared for the usual breadth of the
breaker cards, namely 3 feet. Where the cards are only 18 inches broad,
the lap machine is also made of the same breadth. In the figure we see
the feed-cloth, the scutching barrel, the squirrel suction, and
spreading cage, and the rollers for coiling up the lap. The lever shown
below is for removing the pressure weight from the axis of the lap
rollers, when a full one is to be removed, and replaced by an empty one.
_m_, at the top, is the commencement of the pipe which leads to the
suction fan, or ventilator. The thickness of the lap in this machine
must be nicely regulated, as it determines, in a great measure, the
grist of the card ends, and even the rovings. In 12 hours such a lap
machine will prepare 650 pounds of cotton.

[Illustration: 320]

_Fig._ 320. is the first scutching machine, now never seen except in the
oldest factories. A B is the feed cloth; G H and M N are the two
scutcher frames.

_Carding_ is the next operation in a cotton factory. Cards are destined
to disentangle the individual filaments from each other, and to lay them
lengthwise, instead of being doubled up and convoluted, as they usually
are in leaving the blowing and lap machines. Carding consists in the
mutual action of two opposite surfaces, which are studded thick with
oblique angled hooks. The wires of which these hooks are made must be
very hard drawn in order to render them stiff and elastic. The middle
part of the figures shows one of the staples or double teeth, the
structure of which has been partly explained under CARD. Suppose _a_,
_fig._ 321. to be a piece of a card fillet, and _b_ to be another piece,
each being made fast with pins to a board; the teeth of these two cards
are set in opposite directions, but are very near together, and
parallel. Now suppose a flock or tuft of cotton placed between two such
bristling surfaces. Let _a_ be moved in the direction of its arrow, and
let _b_ be moved in the opposite direction, or even let it remain at
rest. Every filament of the cotton will be laid hold of by each set of
teeth, when their surfaces are thus drawn over each other; the teeth of
_a_ will pull them in a forward direction, while those of _b_ will tend
to retain them, or to pull them backwards. The loops or doublings will,
by both movements, be opened or drawn out, so that the flocks will be
converted into rows of parallel filaments, lying alongside or before
each other. Each tooth will secure to itself one or more of them, and by
the friction of its sides, as well as the hooks of its points, will draw
them to their utmost elongation. Though one stroke of the opposite cards
be inadequate to produce this equable arrangement, yet many repeated
strokes must infallibly accomplish the end in view, of laying the fibres
parallel.

[Illustration: 321 322]

Let us suppose this end effected, and that all the fibres have been
transferred to the card _a_, a transverse stroke of _b_ will draw over
to it a certain number of them, and indeed at each stroke there will be
a new partition between the two cards, with increased parallelism, but
still each card will retain a great deal of the cotton. To make one card
strip another, the teeth of one of them must be placed in a reverse
position, as shown in _fig._ 322.

If _a_ be now drawn in the direction of its arrow along the face of _b_,
it will inevitably comb out all, or almost all, the filaments from it,
since the hooks of _b_ have, in this position, no power of retaining
them. Even the doubled fibres or loops will slip over the sloping point
of _b_, in obedience to the traction of _a_. By considering these two
relative positions of the cards, which take place in hand cards, simply
by reversing one of them, any person will be able to understand the play
of a cylinder card against its flat top, or against another cylinder
card, the respective teeth being in what we may call the teazing
position of _fig._ 321.; and also the play of a cylinder card against
the doffer cylinder, in what may be called the stripping position of
_fig._ 322.

Cylinder cards, so essential to the continuity and dispatch of cotton
factory labour, were the ingenious invention of Lewis Paul of
Northampton, but were greatly improved and brought into nearly their
present operative state by Sir Richard Arkwright. A carding engine
consists of one or more cylinders, covered with card-leather (sometimes
called card cloth), and a set of plane surfaces similarly covered, made
to work against each other, but so that their points do not come into
absolute contact. Some cards consist entirely of cylinders, the central
main cylinder being surrounded by a series of smaller ones called
urchins or squirrels. These are used solely for preparing the coarser
stapled cotton, and sheep’s wool for the wool spinner.

_Fig._ 323. represents a card of excellent construction, which may be
called a _breaker_ and _finisher_, as it is capable of working up the
fleece roll of the lapping machine directly into a card-end or riband
fit for the drawing machine. In fine spinning mills there are always,
however, two cards; one coarser, called a breaker, which turns off the
cotton in a broad fleece of extreme thinness, which is lapped round a
cylinder; and constitutes the material presented to the finisher card,
which has teeth of a finer construction.

[Illustration: 323]

_a_ is one of the two upright slots, which are fixed at each side of the
engine for receiving the iron gudgeons of the wooden cylinders round
which the fleece of the lapping machine is rolled. The circumference of
this coil rests upon a roller _b_, which is made to turn slowly in such
a direction as to aid the unfolding of the lap by the fluted cylinders
_e_. The lap proceeds along the table seen beneath the letter _c_, in
its progress to the fluted rollers, which are an inch and one-sixth in
diameter, and have 28 flutings in their circumference. _g_ is a weight
which hangs upon the axis of the upper roller, and causes it to press
upon the under one: _f_ is the main card drum; _g g g_, the arch formed
by the flat top cards; _h_, the small card cylinder for stripping off
the cotton, and therefore called the doffer, as we have said; _i_, the
doffer-knife or comb for stripping the fleecy web from the doffer; _k l
q m_, the lever mechanism for moving these parts. At _d_ there is a door
for permitting the tenter to have access to the interior of the engine,
and to remove whatever dirt, &c. may happen to fall into it. In _fig._
324. we see the manner of fixing the flat tops _g g_ over the drum; and
for making the matter clearer, three of the tops are removed. Upon the
arched cast-iron side of the frame, a row of strong iron pins _k_ are
made fast in the middle line; and each top piece has, at each of its
ends, a hole, which fits down upon two such opposite pins. _l l_ are
screws whose heads serve as supports to the tops, by coming into contact
with the bottom of the holes, which are not of course bored through the
wood of the tops. By turning the heads of these screws a little the one
way or the other, the pins may be lengthened or shortened in any degree,
so as to set the tops very truly in adjustment with the drum teeth
revolving beneath them, _h´_ is the small runner or urchin, and _i´_ the
large runner; both of which are spirally covered from end to end with
narrow card fillets, in the same manner as the doffer. The main drum is
on the contrary covered with card cloth, in strips laid on parallel to
its axis, with interjacent parallel smooth leather borders. The teeth of
these several cards are set as represented in the figure, and their
cylinders revolve as the arrows indicate. The runners as well as the
doffer cylinder may be set nearer to or farther from the drum _f_; but
the screws intended for this adjustment are omitted in the drawings, to
avoid confusion of the lines.

The card-end or fleece taken off the doffer _h_ by the crank and comb
mechanism _i k m_, passes through the tin plate or brass funnel _n_,
_fig._ 323., whereby it is hemmed in and contracted into a riband, which
is then passed through between a pair of drawing rollers _o_. It is next
received by the rollers _u v_, which carry it off with equable velocity,
and let it fall into the tin cans placed below, or conduct it over a
friction pulley, to be wound along with many other card-ends upon a lap
roller or large bobbin. The latter mechanism is not shown in this
figure. A sloping curved tin or brass plate, channelled or ridged along
its surface, conducts the card ribands separately; there are two smooth
iron rollers for condensing the several ribands, and a wooden pin round
which the ribands are lapped, resting between two leather-covered
rollers, one of which receives motion from mill geering, and imparts it
by friction to the lap roller over it. The iron ends of the lap roller
lie in upright slots, which allow them freedom to rise as the roller
gets filled with fleece.

The two pairs of rollers at _o_, effect the extension of the card-end,
and reduce its size. The under rollers are made of iron and fluted; the
upper ones are also made of iron, but they are covered with a coat of
leather, nicely glued on over a coat of flannel, which two coats render
them both smooth and elastic. Two weights, _w_, press the upper
cylinders steadily down upon the under ones. Between the first and
second pair there is a certain interval, which should be proportioned to
the length of the cotton staple. The second, or that furthest from the
funnel, revolves with greater velocity than the first, and therefore
turns out a greater length of riband than it receives from its fellow;
the consequence is a corresponding extension of the riband in the
interval between the two pairs of rollers.

[Illustration: 324]

The motions of the several parts of the engine are effected in the
following way. The band, _p p_, _fig._ 324., which comes down from the
pulley upon the main shaft near the ceiling of the work-room, drives, by
means of the pulley _q_, the drum _f_, _fig._ 323., with a velocity of
from 120 to 140 revolutions in a minute. From another pulley _r_, on the
axis of the drum, the axis of _t_ is driven by the band _s_ working
round the pulley _t_ on its end. This shaft drives the crank and lever
mechanism of the stripper knife _i_. A third pulley of the same size as
_r_ is fixed just within the frame to the other end of the drum, and
from it a crossed or close band _r´_ goes to a pulley upon the small
runner _h´_, to give this its rapid rotation. Upon the opposite end of
the engine in _fig._ 323., these wheels and pulleys are marked with
dotted lines. Here we may observe, first, a pulley _y_ upon the drum,
and a pulley _a´_, which receives motion from it by means of the band
_z_. The axis of _a´_, carries in front a pinion _m´_, which sets in
motion the wheel _n´_. The latter imparts motion, by means of a pinion
and intermediate wheel _o´_, to the wheel _h_ on the doffer cylinder,
and consequently to that cylinder on the one hand; and it turns, by the
carrier wheel _p´_, a wheel _x_, whose axis is marked also with _x_ in
_fig._ 323., upon the other hand. The axis of _x´_, _fig._ 323.,
carries, towards the middle of the engine, a very broad wheel, which is
represented by a small dotted circle. The toothed wheel _v_ of the
smooth roller _v´_, _fig._ 323., and the two toothed wheels _o o_,
_fig._ 324., of the under rollers _o o_, _fig._ 323., work into that
broad wheel. The wheel of the second or delivery fluted roller is seen
to be smaller than that of the first, by which means the difference of
their velocities is obtained. The large runner _i_ is driven from the
main drum pulley, by means of the band _s´_, and the pulley _u´_, _fig._
323. The said band is crossed twice, and is kept in tension by the
pulley _t´_, round which it passes. The motion of the fluted rollers
_e_, which feed in the cotton fleece, is effected by means of a bevel
wheel _b´_ on the end of the doffer, which works into a similar wheel
_c´_ on the oblique axis _d´_ (dotted lines across the drum), of the
pinion _e´_ upon the lower end of the same axis which turns the wheel
_f´_, upon the under feed roller.

Each of the feed rollers, _fig._ 324., bears a pinion _e e_ at one end,
so that the upper roller turns round with the under one. The roller _b_,
_fig._ 323., is set in motion by means of its wheel _x´_; which is
driven by a wheel _v´_ on the other end of the under feed roller,
through the intervention of the large carrier wheel _w´_. The original
or first motion of _b_ must be as quick as that of the fluted feed
rollers _e_, in order that the former may uncoil as much lap as the
latter can pass on.

The annexed table exhibits the proper velocities of the different
cylinders and rollers of the carding engine, which, however, are not
invariable, but may be modified according to circumstances, by changing
the pinions _e´_, _fig._ 323., and _w´_, according to the quality or
length of the cotton staple. The velocities stated in the table will be
obtained when the pulley _a´_, _fig._ 323., is made greater than _y_ in
the proportion of 3 to 2, and the wheels and pinions have the following
number of teeth: _m´_, 18; _n´_, 50; its pinion, 18; _h_, 128; _x_, 24;
the broad wheel upon the shaft of _x_, 37 teeth; the wheel _o_ of the
first fluted roller, 35; that of the second, 21; _v_, 44; _b´_ and _e´_,
54; _e´_, 10; _f´_, 63.

  +--------------------------+--------+----------+-----------+---------+
  |   Names of the parts.    |Diameter| Circum-  |Revolutions|Velocity.|
  |                          |  in    | ference  |  in one   |         |
  |                          |inches. |in inches.|  minute.  |         |
  +--------------------------+--------+----------+-----------+---------+
  |Drum _f_                  | 35     | 109·9    |  130      |  142·87 |
  |Doffer _h_                | 14     |  43·96   |    4·38   |  192·5  |
  |Runner or urchin _i´_     |  6·25  |  19·62   |    5·     |   98·1  |
  |Ditto _h´_                |  3·5   |  11·     |  470·     | 5170·   |
  |Fluted feed roller _e_    |  1·167 |   3·664  |    0·696  |    2·55 |
  |First drawing roller _o_  |  1·    |   3·14   |   68·71   |  215·75 |
  |Second ditto              |  1·167 |   3·664  |  114·52   |  419·6  |
  |Smooth delivery roller _v_|  2·5   |   7·85   |   54·66   |  429·08 |
  +--------------------------+--------+----------+-----------+---------+

The operation of the runners, _h´_ and _i´_, becomes very plain on
comparing their speed with one another and with that of the main-drum,
and taking into account the direction of the card teeth. The cotton
wool, taken off from the feed-rollers by the drum, is caught by the
opposite teeth of the large runner _i´_, which, on account of its slower
surface rotation (98 inches per minute) may be considered to be at rest
with reference to the drum, and therefore, by holding the cotton in its
teeth, will commence its carding. The small runner _h´_, in consequence
of its greater surface velocity (5170 inches per minute) will comb the
cotton-wool back out of the teeth of the large runner, but it will give
it up in its turn to the swifter teeth of the drum, which, in carrying
it forwards, encounters the teeth of the top cards, and delivers up the
filaments to their keeping for some time. We thus see how essential the
runners are to the perfection as well as to the acceleration of the
carding process for ordinary cotton wool, though for the slenderer and
longer filaments of the sea-island kind they are not so well adapted. In
cleaning the carding-engines the little runner must be looked to every
time that the drum is examined. The large runner and the doffer require
to be cleaned together. The quantity of cotton spread upon the
feed-cloth, the velocity of it, and of the drawing-rollers, must all be
carefully adjusted to the grist of the yarn intended to be spun.

[Illustration: 325]

Suppose the sizes and velocities to be as represented in the preceding
table, that the engine is a double card 36 inches broad, and that it is
furnished with a lap from the lap-machine of which 30 feet in length
weigh 5 lbs. In one minute the surface of the feed-rollers, _e_, passes
2·55 inches of that lap onwards; in the same time the main drum _f_ will
work it off. To card the whole 30 feet, therefore, 141 minutes, or 2
hours and 21 minutes will be required. In this time the circumference of
the rollers, _u v_, moves through a space of 141 × 42,908 in. = 5042
ft., and delivers a card-end of that length, weighing 5 lbs., _minus_ 6
per cent. for waste, that is 4 lbs. 11-1/2 oz. One pound will form a
riband 1072 feet long, being, according to the English mode of counting,
about number 1/3, or 0·357. The extension of the cotton-fleece to this
degree proceeds as follows:--In the 141 minutes which the feed-rollers
take to introduce the 30 feet of lap, the doffer, _h_, makes 617·58
revolutions, and the comb, or doffer knife, _i_, detaches from the
doffer teeth, a thin fleecy web of 2262 feet in length. The first
drawing pair of fluted rollers, by its quick motion, with the aid of the
funnel, _m_, converts this fleece into a riband 2535 feet long. The
second pair of the fluted rollers extends this riband to 4390 feet,
since their surface velocity is greater than the first pair in that
proportion. The slight elongation (of only 112 feet, or about 1/44)
which takes place between the delivery fluted rollers and the smooth
cylinders, _v_, _u_, serves merely to keep the card-end steadily upon
the stretch without folding. _Fig._ 325. is a plan of the card and the
fleece, where _h_ is the cylinder, _n_ is the funnel, _u_ the pressing
rollers, and _h´_ the card-ends in the can.

[Illustration: 326 327]

_Figs._ 326, 327. represent skeletons of the old cards to facilitate the
comprehension of these complex machines. _Fig._ 326. is a plan; F is the
main drum; M M is the doffer knife or comb; G, the carded fleece hemmed
in by the funnel _a_, pressed between the rollers _b_, and then falling
in narrow fillets into its can. _Fig._ 327. K L are the feed rollers; A
B, the card drum; C D, the tops; E F, the doffer card; M N, the doffer
knife; _d_, _b_, _c_, the card-end passing between compressing rollers
into the can _a_.

_The drawing and doubling_ are the next operation. The ends, as they
come from the cards, are exceedingly tender and loose, but the filaments
of the cotton are not as yet laid so parallel with each other as they
need to be for machine spinning. Before any degree of torsion therefore
be communicated, a previous process is required to give the filaments a
level arrangement in the ribands. The drawing out and doubling
accomplish this purpose, and in a manner equally simple and certain. The
means employed are drawing-rollers, whose construction must here be
fully explained, as it is employed in all the following machines; one
example of their use occurred, indeed, in treating of the cards.

[Illustration: 328]

Let _a_ and _b_, _fig._ 328., represent the section of two rollers lying
over each other, which touch with a regulated pressure, and turn in
contact upon their axes, in the direction shown by the arrows. These
rollers will lay hold of the fleecy riband presented to them at _a_,
draw it through between them, and deliver it quite unchanged. The length
of the piece passed through in a given time will be equal to the space
which a point upon the circumference of the roller would have percured
in the same time; that is, equal to the periphery of one of the rollers
multiplied by the number of its entire revolutions. The same thing holds
with regard to the transmission of the riband through between a second
pair of rollers, _c_, _d_, and a third, _e_, _f_. Thus the said riband
issues from the third pair exactly the same as it entered at _a_,
provided the surface speed of all the rollers be the same. But if the
surface speed of _c_ and _d_ be greater than that of _a_ and _b_, then
the first-named pair will deliver a greater length of riband than the
last receives and transmits to it. The consequence can be nothing else
in these circumstances than a regulated drawing or elongation of the
riband in the interval betwixt _a_, _b_, and _c_, _d_, and a
condensation of the filaments as they glide over each other, to assume a
straight parallel direction. In like manner the drawing may be repeated
by giving the rollers, _e_, _f_, a greater surface speed than that of
the rollers, _c_ and _d_. This increase of velocity may be produced,
either by enlarging the diameter, or by increasing the number of turns
in the same time, or finally by both methods conjoined. In general the
drawing-machine is so adjusted, that the chief elongation takes place
between the second and third pairs of rollers, while that between the
first and second is but slight and preparatory. It is obvious, besides,
that the speed of the middle pair of rollers can have no influence upon
the amount of the extension, provided the speed of the first and third
pair remains unchanged. The rollers, _a_, _b_, and _c_, _d_, maintain
towards each other continually the same position, but they may be
removed with their frame-work, more or less, from the third pair, _e_,
_f_, according as the length of the cotton staple may require. The
distance of the middle point from _b_ and _d_, or its line of contact
with the upper roller, is, once for all, so calculated, that it shall
exceed the length of the cotton filaments, and thereby that these
filaments are never in danger of being torn asunder by the second pair
pulling them while the first holds them fast. Between _d_ and _f_, where
the greatest extension takes place, the distance must be as small as it
can be without risk of tearing them in that way; for thus will the
uniformity of the drawing be promoted. If the distance between _d_ and
_f_ be very great, a riband passing through will become thinner, or
perhaps break in the middle; whence we see that the drawing is more
equable, the shorter is the portion submitted to extension at a time,
and the nearer the rollers are to each other, supposing them always
distant enough not to tear the staple.

The under rollers _b d f_ are made of iron, and, to enable them to lay
firmer hold of the filaments, their surfaces are fluted with triangular
channels parallel to their axes. The upper rollers, _a c e_, are also
made of iron, but they are smooth, and covered with a double coating,
which gives them a certain degree of softness and elasticity. A coat of
flannel is first applied by sewing or gluing the ends, and then a coat
of leather in the same way. The junction edges of the leather are cut
slanting, so that when joined by the glue (made of isinglass dissolved
in ale) the surface of the roller may be smoothly cylindrical. The top
rollers are sometimes called the _pressers_, because they press by means
of weights upon the under ones. These weights are suspended to the
slight rods _k k´_; of which the former operates on the roller _e_
alone, the latter on the two rollers _a_ and _e_ together. For this
purpose the former is hung to a C shaped curve _i_, whose upper hook
embraces the roller _e_; the latter to a brass saddle _h_, which rests
upon _a_ and _c_. A bar of hard wood, _g_, whose under surface is
covered with flannel, rests, with merely its own weight, upon the top
rollers, and strips off all the loose hanging filaments. Similar bars
with the same view are made to bear up under the fluted rollers _b d f_,
and press against them by a weight acting through a cord passing over a
pulley. Instead of the upper dust-covers, light wooden rollers covered
with flannel are occasionally applied.

Were the drawing of a riband continued till all its fibres acquired the
desired degree of parallelism, it would be apt, from excessive
attenuation, to tear across, and thereby to defeat the purpose of the
spinner. This dilemma is got rid of in a very simple way, namely, by
laying several ribands together at every repetition of the process, and
incorporating them by the pressure of the rollers. This practice is
called _doubling_. It is an exact imitation of what takes place when we
draw a tuft of cotton wool between our fingers and thumb in order to
ascertain the length of the staple, and replace the drawn filaments over
each other, and thus draw them forth again and again, till they are all
parallel and of nearly equal length. The doubling has another advantage,
that of causing the inequalities of thickness in the ribands to
disappear, by applying their thicker to their thinner portions, and
thereby producing uniformity of substance.

[Illustration: 329 330]

The drawing frame, as shown in section in _figs._ 328. 330., and in a
back view in _fig._ 329., will require, after the above details, little
further explanation. _l l_ are the weights which press down the top
rollers upon the under ones, by means of the rods _k k´_ and hook _i_.
Each fluted roller is, as shown at _f_, _fig._ 329., provided in the
middle of its length with a thinner smooth part called the _neck_,
whereby it is really divided into two fluted portions, represented by _e
e_ in the figure. Upon this middle neck in the pressure rollers, the
hook _i_ and the saddle _h_ immediately bear, as shown in the former
_fig._ 328. The card-ends, to the number probably of six, are introduced
to the drawing frame either from tin cans, placed at _e e_, _fig._ 330.,
and at A, _fig._ 329., or from lap-bobbins; and, after passing through
it, the ribands or slivers are received either into similar tin cans, as
_g_, or upon other lap-bobbins upon the other side. These appendages may
be readily conceived, and are therefore not exhibited in all the
drawings. Three of the slivers being laid together, are again introduced
to the one fluted portion _a b_, _fig._ 328., and three other slivers to
the other portion. The sloping curved tin or brass plate _s_, _fig._
329., with its guide pins _t_, serves to conduct the slivers to the
rollers. When the two threefold slivers have passed through between the
three pairs of rollers, and been thereby properly drawn, they run
towards each other in an oblique direction, behind the last roller pair
_e f_, _fig._ 328., and unite, on issuing through the conical funnel
_m_, _fig._ 329., into a single riband or spongy sliver; which is
immediately carried off with equable velocity by two smooth cast-iron
rollers, _n o_, _fig._ 329. and 330. and either dropped into a can, or
wound upon a large bobbin. The surface speed of these rollers is made a
trifle greater than that of the delivery drawing rollers, in order to
keep the portion of sliver between them always in an extended state.
Four fluted drawing portions are usually mounted in one drawing frame,
which are set a-going or at rest together. To save all unnecessary
carrying of the cans from the back to the front of the frame, the
drawing heads are so placed, that the first and third, discharge their
slivers at the one side, and the second and fourth at the other. By this
arrangement, the cans filled behind one head, are directly pushed aside
in front of the next drawing head; by which alternate distribution the
work goes on without interruption.

The _fast_ pulley _u_, _fig._ 330., by which the whole machine is
driven, derives its motion from the main shaft of the mill by means of
the band _w_. The similar pulley _x_, which sits loose upon the axis,
and turns independently of it, is called the loose pulley; both together
being technically styled _riggers_. When the operative desires to stop
the machine, he transfers the band from the fast to the loose pulley by
means of a lever, bearing a fork at its end, which embraces the band.
Upon _y_, four pulleys such as _x_ are fixed, each of which sets in
motion a drawing head, by means of a band like _w_ going round the
pulleys _x_ and _u_. On account of the inverted position of the heads,
which requires the motion of _u_ to be inverted, the bands of the first
and third heads are open, but those of the second and fourth are
crossed. Every head is provided with a loose pulley _v_, as well as the
fast pulley _u_, in order to make the one stop or move without affecting
the others. The shaft of the pulley _u_ is the prolonged shaft of the
backmost fluted roller _f_. It carries besides a small pulley _q_,
which, by means of the band _r_, and the pulley _p_, _fig._ 329., sets
in motion the undermost condensing roller _o_. The upper roller _n_,
presses with its whole weight upon it, and therefore turns by friction.
The toothed wheel-work, by which the motions are communicated from the
backmost fluted roller to the middle and front ones, are seen in _fig._
330.

The wheel _f_, _fig._ 328., of 20 teeth, works in a 44-toothed
carrier-wheel, on whose axis there are two smaller wheels; 2 with 26
teeth, and 1 with 22 teeth. The wheel _d_, _fig._ 330., of the middle
roller, and the wheel _b_ of the front roller, are set in motion by
other carrier wheels; the first has 27 teeth, and the last 40. For every
revolution of _b_, the roller _d_ makes nearly 1-3/4 turns, and the
roller _f_, 4 revolutions. The top rollers revolve, as we have stated,
simply by the friction of contact with the lower ones. Now suppose the
diameter of the rollers _b_ and _d_ to be 1 inch or 12 lines, that of
_f_, 1-1/4 inches or 15 lines, the surface velocities of the three pairs
of rollers in the series will be as 1, 1-3/4, and 5. Every inch of the
cotton sliver will be therefore extended between the first and second
pair of rollers into 1-3/4 inches, and between the second and third or
delivery pair into 5 inches; and after the sliver has passed through all
the four drawing heads, its length will be increased 625 times = 5 × 5 ×
5 × 5.

The further the drawing process is pushed, the more perfectly will its
object be accomplished; namely the parallelism of the filaments. The
fineness of the appearance of the sliver after the last draught depends
upon the number of doublings conjointly with the original fineness and
number of drawings. The degree of extension may be increased or
diminished, by changing the wheels in _fig._ 330., for others with a
different number of teeth. Thus the grist or fineness of the sliver may
be modified in any desired degree; for, when the subsequent processes of
the mill remain the same, the finer the drawings the finer will be the
yarn. For spinning coarse numbers or low counts, for example, six
card-ends are usually transmitted through the first drawing head, and
converted into one riband. Six such ribands again form one in the second
draught; six of these again go together into the third sliver; and this
sliver passes five-fold through the last draught. By this combination
1080 of the original card-ends are united in the finished drawn sliver =
6 × 6 × 6 × 5. The fineness of the sliver is, however, in consequence of
these doublings not increased but rather diminished. For, by the
drawing, the card-end has been made 625 times longer, and so much
smaller; by the doubling alone it would have become 1080 times thicker;
therefore the original grist is to the present as 1, to the fraction
625/1080; that is, supposing 1072 feet of the riband delivered by the
card to weigh one pound, 625 feet, the sliver of the last drawing, will
also weigh a pound, which corresponds in fineness to number 0·24, or
nearly 1/4.

The rearmost or last drawing roller has a circumference of nearly 4
inches, and makes about 150 revolutions per minute; hence, each of these
drawing heads may turn off 35,000 feet of sliver in 12 hours.

Some manufacturers have lately introduced a double roller beam, and a
double draught at the same doubling, into their drawing frames. I have
seen this contrivance working satisfactorily in mills where low counts
were spun, and where the tube roving frame was employed; but I was
informed by competent judges, that it was not advisable where a level
yarn was required for good printing calicoes.

The loss which the cotton suffers in the drawing frame is quite
inconsiderable. It consists of those filaments which remain upon the
drawing rollers, and collect, in a great measure, upon the flannel
facing of the top and bottom cleaner bars. It is thrown among the top
cleanings of the carding engine. When from some defect in the rollers,
or negligence in piecing the running slivers, remarkably irregular
portions occur in the ribands, these must be torn off, and returned to
the lap machine to be carded anew.

The fifth operation may be called the _first spinning process_, as in
it, the cotton sliver receives a twist; whether the twist be permanent
as in the bobbin and fly frame, or be undone immediately, as in the
tube-roving machine. In fact, the elongated slivers of parallel
filaments could bear little further extension without breaking asunder,
unless the precaution were taken to condense the filaments by a slight
convolution, and at the same time to entwine them together. The twisting
should positively go no further than to fulfil the purpose of giving
cohesion, otherwise it would place an obstacle in the way of the future
attenuation into level thread. The combination of drawing and twisting
is what mainly characterizes the spinning processes, and with this fifth
operation therefore commences the formation of yarn. As however a sudden
extension to the wished-for fineness is not practicable, the draught is
thrice repeated in machine spinning, and after each draught a new
portion of torsion is given to the yarn, till at last it possesses the
degree of fineness and twist proportioned to its use.

The preliminary spinning process is called _roving_. At first the
torsion is slight in proportion to the extension, since the solidity of
the still coarse sliver needs that cohesive aid only in a small degree,
and looseness of texture must be maintained to facilitate to the utmost
the further elongation.

[Illustration: 331]

_Fig._ 331. is a section of the can roving frame, the ingenious
invention of Arkwright, which till within these 14 years was the
principal machine for communicating the incipient torsion to the spongy
cord furnished by the drawing heads. It differs from that frame in
nothing but the twisting mechanism; and consists of two pairs of drawing
rollers, _a_ and _b_, between which the sliver is extended in the usual
way; _c_ are brushes for cleaning the rollers; and _d_ is the weight
which presses the upper set upon the lower. The wiping covers (not shown
here) rest upon _a b_. The surface speed of the posterior or second pair
of rollers is 3, 4, or 5 times greater than that of the front or
receiving pair, according to the desired degree of attenuation. Two
drawn slivers were generally united into one by this machine, as is
shown in the figure, where they are seen coming from the two cans _e e_,
to be brought together by the pressure rollers, before they reach the
drawing rollers _a b_. The sliver, as it escapes from these rollers, is
conducted into the revolving conical lantern _g_, through the funnel _f_
at its top. This lantern-can receives its motion by means of a cord
passing over a pulley _k_, placed a little way above the step on which
it turns. The motion is steadied by the collet of the funnel _f_, being
embraced by a brass busk. Such a machine generally contained four
drawing heads, each mounted with two lanterns; in whose side there was a
door for taking out the conical coil of roving.

The motion imparted to the back roller by the band pulley or rigger _m_,
was conveyed to the front one by toothed wheel work.

The vertical guide pulley at bottom _n_, served to lead the driving band
descending from the top of the frame round the horizontal whorl or
pulley upon the under end of the lantern. The operation of this
can-frame was pleasing to behold; as the centrifugal force served both
to distribute the soft cord in a regular coil, and also to condense a
great deal of it most gently within a moderate space. Whenever the
lantern was filled, the tenter carried the roving to a simple machine,
where it was wound upon bobbins by hand. Notwithstanding every care in
this transfer, the delicate texture was very apt to be seriously
injured, so as to cause corresponding injuries in every subsequent
operation, and in the finished yarn. Messrs. Cocker and Higgins, of
Salford, had the singular merit, as I have said, of superseding that
beautiful but defective mechanism, which had held a prominent place in
all cotton mills from almost the infancy of the factory system, by the
following apparatus.

_The Bobbin and Fly frame_ is now the great roving machine of the cotton
manufacture; to which may be added, for coarse spinning, the tube
roving frame. Of such a complicated machine as the bobbin and fly frame,
it is not possible to give an adequately detailed description in the
space due to the subject in this Dictionary. Its mechanical combinations
are however so admirable as to require such an account as will make its
functions intelligible by the general reader.

[Illustration: 332]

_Fig._ 332. exhibits a back view of this machine; and _fig._ 333. a
section of some of the parts not very visible in the former figure. The
back of the machine is the side at which the cotton is introduced
between the drawing rollers.

[Illustration: 333]

The cans, or lap-bobbins filled with slivers at the drawing frame, are
placed in the situation marked B, _fig._ 333., in rows parallel with the
length of the machine. The sliver of each can or the united slivers of
two contiguous cans are conducted upwards along the surface of a sloping
board _f_, and through an iron staple or guide _e_, betwixt the usual
triple pair of drawing rollers, the first of which is indicated by _a_,
_b_. In _fig._ 332., for the purpose of simplifying the figure, the
greater part of these rollers and their subordinate parts are omitted.
After the slivers have been sufficiently extended and attenuated between
the rollers, they proceed forwards, towards the spindles _i i i_, where
they receive the twist, and are wound upon the bobbins _h_. The machine
delineated contains thirty spindles, but many bobbin and fly frames
contain double or even four times that number. Only a few of the
spindles are shown in _fig._ 332., for fear of confusing the drawing.

[Illustration: 334]

With regard to the drawing functions of this machine, I have already
given abundant explanation, so far as the properties and operation of
the rollers are concerned. The frame-work of this part of the machine,
called the _roller-beam_, is a cast iron bench, upon which nine bearers
_c_, are mounted for carrying the rollers. The fluted rollers _a a a_,
_fig._ 334., are constructed in four pieces for the whole length, which
are parted from each other by thinner smooth cylindric portions _z_,
called necks. Seven such partings for four rollers, and one parting for
two rollers, constitute together the 30 fluted rollers of which the
whole series consists. The coupling of these roller subdivisions into
one cylinder, is secured by the square holes _x_, and square pins _y_,
_fig._ 334., which fit into the holes of the adjoining subdivision. The
top or pressure rollers _b_, are two-fold over the whole set; and the
weighted saddle presses upon the neck _w_, which connects every pair, as
was already explained under _fig._ 329. These weights _g_, _g_, _fig._
333., are applied in this as in the _drawing frame_; _d_, are the bars
faced with flannel for cleaning the top rollers. A similar bar is
applied beneath the rollers, to keep the flutings clean.

[Illustration: 335]

The structure and operation of the spindles _i_, may be best understood
by examining the section _fig._ 335. They are made of iron, are
cylindrical from the top down to _a_², but from this part down to the
steel tipt rounded points they are conical. Upon this conical portion
there is a pulley _k_, furnished with two grooves in its circumference,
in which the cord runs that causes the spindle to revolve. The wooden
bobbin _h_, is slid upon the cylindrical part, which must move freely
upon it, as will be presently explained. To the bobbin another
two-grooved pulley or whorl _q_ is made fast by means of a pin _r_,
which passes through it; by removing this pin, the bobbin can be
instantly taken off the spindle. The upper end of the spindle bears a
fork _s t_, which may be taken off at pleasure by means of its
left-handed screw; this fork or flyer, has a funnel-formed hole at _v_.
One arm of the fork is a tube _s_, _u_, open at top and bottom; the leg
_t_, is added merely as a counterpoise to the other. In _fig._ 333., for
the sake of clearness, the forks or flyers of the two spindles here
represented are left out; and in _fig._ 332. only one is portrayed for
the same reason. It is likewise manifest from a comparison of these two
figures that the spindles are alternately placed in two rows, so that
each spindle of the back range stands opposite the interval between two
in the front range. The object of this distribution is economy of space,
as the machine would need to be greatly longer if the spindles stood all
in one line. If we suppose the spindles and the bobbins (both of which
have independent motions) to revolve simultaneously and in the same
direction, their operation will be as follows: The sliver properly drawn
by the fluted rollers, enters the opening of the funnel _v_, proceeds
thence downwards through the hole in the arm of the fork, runs along its
tube _u_, _s_, and then winds round the bobbin. This path is marked in
_fig._ 335. by a dotted line.

The revolution of the spindles in the above circumstances effects the
twisting of the sliver into a soft cord; and the flyer _s_, _t_, or
particularly its tubular arm _s_, lays this cord upon the bobbin. Were
the speed of the bobbins equal to that of the spindles, that is, did the
bobbin and spindle make the same number of turns in the same time, the
process would be limited to mere twisting. But the bobbin anticipates
the flyers a little, that is, it makes in a given time a somewhat
greater number of revolutions than the spindle, and thereby effects the
continuous winding of the cord upon itself. Suppose the bobbin to make
40 revolutions, while the spindle completes only 30; 30 of these
revolutions of the bobbin will be inoperative towards the winding-on,
because the flyers follow at that rate, so that the cord or twisted
sliver will only be coiled 10 times round the bobbin, and the result as
to the winding-on will be the same as if the spindle had stood still,
and the bobbin had made 40 - 30 = 10 turns. The 30 turns of the spindles
serve, therefore, merely the purpose of communicating twist.

The mounting and operation of the spindles are obviously the same as
they are upon the household flax wheel. In the bobbin and fly frame
there are some circumstances which render the construction and the
winding-on somewhat difficult, and the mechanism not a little
complicated. It may be remarked in the first place, that as the cord is
wound on, the diameter of the bobbin increases very rapidly, and
therefore every turn made round it causes a greater length of roving to
be taken up in succession. Were the motions of the bobbins to continue
unchanged in this predicament, the increased velocity of the winding-on
would require an increased degree of extension, or it would occasion
the rupture of the cord, because the front fluted rollers move with
uniform speed, and therefore deliver always the same length of sliver in
the same time. It is therefore necessary to diminish the velocity of the
bobbins, or the number of their turns, in the same proportion as their
diameter increases, in order that the primary velocity may remain
unchanged. Moreover, it is requisite for the proper distribution of the
cord upon the bobbin, and the regular increase of its diameter, that two
of its successive convolutions should not be applied over each other,
but that they should be laid close side by side. This object is attained
by the up and down sliding motion of the bobbin upon the spindle, to the
same extent as the length of the bobbin barrel. This up and down motion
must become progressively slower, since it increases the diameter of the
bobbin at each range, by a quantity equal to the diameter of the sliver.
What has now been stated generally, will become more intelligible by an
example.

Let it be assumed that the drawing rollers deliver, in 10 seconds, 45
inches of roving, and that this length receives 30 twists. The spindles
must, in consequence, make 30 revolutions in 10 seconds, and the bobbins
must turn with such speed, that they wind up the 45 inches in 10
seconds. The diameter of the bobbin barrels being 1-1/2 inches, their
circumference of course 4-1/2 inches, they must make 10 revolutions more
in the same time than the spindles. The effective speed of the bobbins
will be thus 30 + 10 = 40 turns in 10 seconds. Should the bobbins
increase to 3 inches diameter, by the winding-on of the sliver, they
will take up 9 inches at each turn, and consequently 45 inches in 5
turns. Their speed should therefore be reduced to 30 + 5 = 35 turns in
10 seconds. In general, the excess in number of revolutions, which the
bobbins must make over the spindles, is inversely as the diameter of the
bobbins. The speed of the bobbins must remain uniform during the period
of one ascent or descent upon the spindle, and must diminish at the
instant of changing the direction of their up and down motion; because a
fresh range of convolutions then begins with a greater diameter. When,
for example, 30 coils of the sliver or roove are laid in one length of
the bobbin barrel, the bobbin must complete its vertical movement up or
down, within 30 seconds in the first case above mentioned, and within 60
seconds in the second case.

The motions of the drawing rollers, the spindles, and bobbins, are
produced in the following manner:--A shaft _c´_, _fig._ 332. and 333.,
extending the whole length of the machine, and mounted with a fly wheel
_d´_, is set in motion by a band from the running pulley upon the shaft
of the mill, which actuates the pulley _a´_. _b´_ is the loose pulley
upon which the band is shifted when the machine is set at rest. Within
the pulley _a´_, but on the outside of the frame, the shaft _c´_ carries
a toothed wheel _b_² with 50 teeth, which by means of the intermediate
wheel _c_² turns the wheel _d_² upon the prolonged shaft of the backmost
fluted roller (_m_², _fig._ 333.) This wheel _d_² has usually 54 teeth;
but it may be changed when the roove is to receive more or less twist;
for as the spindles revolve with uniform velocity, they communicate the
more torsion the less length of sliver is delivered by the rollers in a
given time. Upon the same shaft with _d_², a pinion _e_² of 32 teeth is
fixed, which works in a wheel _f_² of 72 teeth. Within the frame a
change pinion _g_² is made fast to the shaft of _f_². This pinion, which
has usually from 24 to 28 teeth, regulates the drawing, and thereby the
fineness or number of the roving. It works in a 48-toothed wheel _h_²
upon the end of the backmost fluted roller _a_, _fig._ 333. The other
extremity of the same roller, or, properly speaking, line of rollers,
carries a pinion _l_², furnished with 26 teeth, which, by means of the
broad intermediate wheel _k_², sets in motion the pinion _i´_² of 22
teeth upon the middle roller. When the diameter of all the drawing
rollers is the same, suppose 1 inch, their proportional velocities will
be, with the above number of teeth in the wheel work, if _g_² have 24
teeth, as 1 : 1·18 : 4·5; and the drawn sliver will have 4-1/2 times its
original length. The front or delivery roller of the drawing frame is of
late years usually made 1-1/4 or 1-3/8 inches in diameter. If 625 feet
of the sliver from the drawing frame weighed one pound, 2790 feet of the
roving will now go to this weight, and the number will be 1·12; that is,
1 hank and 12 hundredths to the pound. The front pair of fluted rollers
makes about 90 revolutions, and delivers 282·6 inches of roving in the
minute, when of one inch diameter.

The spindles _i_, (_fig._ 332. and 333.), rest, with their lower ends,
in steps _l_, which are fixed in an immoveable beam or bar _m_. To
protect it from dust and cotton filaments, this beam is furnished with a
wooden cover _n_, in which there are small holes for the passage of the
spindles right over the steps. In _fig._ 332., two of the eight covers
_n_, which compose the whole range _m_, are removed to let the steps be
seen. The cylindrical part of each spindle passes through a brass ring
_o_; and all these 30 rings, whose centres must be vertically over the
steps _l_, are made fast to the copping beam _p_. This beam is so
called, because it is destined not merely to keep the spindles upright
by the rings attached to it, but, at the same time, to raise and lower
along the spindles the bobbins which rest on these rings; for which
purpose the two racks, or toothed bars _m_² _m_², made fast to it, are
designed, as will be presently explained. To effect the revolution of
the spindles, there are attached to the main shaft _c´_ two whorls or
pulleys _e´ f´_, each bearing four grooves of equal diameter. Each of
these pulleys puts one half of the spindles in motion, by means of a
cord, which, after going round the whorls _k_, turns four times about
the pulleys of the shaft _c´_. Two guide pulleys _h´_, each
four-grooved, and two others _i´_, with a single groove, which turn
independently of the others, upon the above shaft, serve to give the
whorl cords the proper direction, as well as to keep them tight. The
spindles revolve 200 times or thereby in the minute; and therefore
impart two turns or twists to every three inches of the roving.

The revolution of the bobbins is independent of that of the spindles,
although it likewise proceeds from the shaft _c´_, and differs from it
in being a continually retarded motion. The simplest method of effecting
this motion, is by means of the wooden or tin plate cone _k´´_, which
revolves equally with the shaft _c´_, and at the same time slides along
it.

[Illustration: 336 337]

The manner in which this operates is shown in section in _fig._ 336.
Here, we perceive the rod _q_², which extends from the base towards the
narrow end of the truncated cone, and _p_² a forked bearer or carrier
made fast to the shaft _c´_ by a screw, which compels the cone by means
of that rod, to obey the movements of _c´_. In the large end of the cone
there is an aperture, through which the bearer can be got at. The
smaller end carries outside a projection _o_², provided with a groove,
which is embraced by the forked end of a rod _q´_, _fig._ 337., that
serves to shove the cone along upon the shaft _c´_. Directly under the
cone, there is an upright round pillar _p´_, upon which the holder _o´_
of the two guide pulleys _l´_ is adjustable. A bar _r_² placed
along-side of the holder, prevents its turning round, but allows it to
slide along _p´_ by friction. The weight of the holder and the pulley is
sufficient to distend the endless band _n´_, which runs from the cone
_k´_, through under the pulley _l´_, and round the small drum _m´_ on
the shaft _s_². A pulley or whorl _t_² with four grooves, is made fast
by means of a tube to this shaft, and slides along it backwards and
forwards, without ever ceasing to follow its revolutions. The shaft
possesses for this purpose a long fork, and the interior of the tube a
corresponding tongue or catch. There is besides upon the tube beneath
the pulley, at _u_², a groove that goes round it, in which the staple or
forked end of an arm like _v_², _fig._ 333., made fast to the copping
beam _p_, catches. By the up and down movement of that beam, the pulley
_t_² takes along with it the arm that embraces the tube, which therefore
rises and falls equally with the bobbins _h´_, and their pulleys or
whorls _q_. This is requisite, since the bobbins are made to revolve by
the pulleys _t_², by means of 2 endless cords or bands.

[Illustration: 338 339]

The most intricate part of the mechanism is the adjustment, by which the
revolution of the bobbins is continually retarded, and their up and
down, or copping motion, along the spindles, is also retarded in like
proportion. The vertical pulley _f´_, (towards the left end of the shaft
_c´_) has at its right side a somewhat larger _disc_ or sheave _g´_,
with a perfectly uniform, but not a very smooth surface. Upon this
sheave, a smaller horizontal pulley _x´_ rubs, whose upper face is
covered with leather to increase the friction. The under end of the
shaft _y_² of the pulley _x´_ turns in a step, which is so connected
with the arm _v´_ of the large bent lever _t´ v´_, that it always stands
horizontally, whatever direction the arms of that lever may assume. The
shaft _y_² is steadied at top by an annular holder or bush, which
embraces the fast arm _x_² with its forked end. Upon its opposite side,
this arm carries a pulley _y_², upon which a cord goes, that is made
fast to the holder of the shaft _y_², and loaded with the weight _z´_.
The weight presses the pulley _x´_ against the surface of _g´_, in such
wise as to effect the degree of friction necessary in order that the
revolution of _g´_ may produce an uninterrupted revolution in _x´_. A
pinion _w´_, whose length must be equal at least to the semi-diameter of
the sheave _g´_, is placed upon the under end of the shaft _y_². It has
22 teeth, and takes into a 62-toothed horizontal wheel _z_². Upon the
upper end of this wheel the conical pinion _a_³ is made fast, which may
be changed for changing the speed, but usually has from 28 to 30 teeth.
By this pinion the conical wheel _b_³ is turned, which has 30 teeth, and
whose shaft is _c_³. This shaft carries upon its opposite end a
six-leaved pinion, _d_³, which takes into the calender wheel _f_³,
formed with cogs like a trundle, upon the long shaft _e_³. In _fig._
338. the wheel _f_³ is exhibited with its pinion _d_³. Here we may
remark that in the circumference of the wheel there is a vacant place,
_g_³, void of teeth. When by the motion of the wheel, the pinion comes
opposite to this opening, it turns round about the last tooth of the
wheel, falls into the inside of the toothed circle marked by the dotted
lines, and thus gives now an inverse movement to the wheel _f_³, while
itself revolves always in the same direction. This reversed motion
continues till the opening _g_³ comes once more opposite to the pinion,
when this turns round about the last tooth of that side, and begins
again to work in the exterior teeth. Thus, by the uniform motion of _d_³
and its dependent parts, the wheel _f_³, with its shaft _e_³, revolves
alternately to the right hand and the left. That this result may ensue,
the shaft _c_³ of the pinion must be able to slide endwise, without
losing its hold of _a_³ and _b_³. This adjustment is effected by placing
the end of the said shaft, nearest _b_³, in a box or holder _i_³, in
which it can turn, and which forms a vertical tube to this box, as a
downward prolongation which is fixed to the tail of the conical pinion
_a_³. _Fig._ 339. shows this construction in section upon an enlarged
scale. The second bearer of the shaft nearest _d_³, must possess
likewise the means of lateral motion. When therefore the pinion _d_³
shifts through the opening of the wheel _f_³ outwards or inwards, its
shaft _c_³, makes a corresponding small angular motion upon the pivot of
_a_³, by means of the tube _i_³; _a_³ and _b_³ remain thereby completely
in geer with one another.

The above-described alternate revolutions of the wheel _f_³ serve to
produce the up and down motions of the bobbins. The shaft _e_³ has for
this purpose two pinions _n_² _n_², which work in the rack teeth _m_²
_m_² of the copping rail _p_, and thus alternately raise and sink it
with the bobbins which rest upon it. The weight of the copping beam and
all its dependent parts, is poised by two counterweights _m_⁴, whose
cords run over the pulleys _o_⁴ _o_⁴ _o_⁴, _fig._ 332., and have their
ends made fast to the frame, so as to make the upwards motion as easy as
the downwards. The two upper pulleys out of the three of each weight,
are fixed to the frame; the under one, round which the cord first runs,
is attached to the copping beam, rising and falling along with it.

[Illustration: 340 341]

As long as the friction disc _x´_ remains at the same height, the pulley
_g´_ derives its motion from the same circle of the said disc, and the
up and down motion of the copping beam is also uniform. But when that
disc ascends so as to describe with its edge a small circle upon the
face of _g´_, its motion must become proportionally more slow. This is
the method, or principle of retarding the copping motions of the
bobbins. It has been shown, however, that the rotation of the bobbins
should be also retarded in a progressive manner. This object is effected
by means of the cone _k´_, which, as the band _n´_ progressively
approaches towards its smaller diameter, drives the pulleys or whorls
_q_ of the bobbins with decreasing speed, though itself moves uniformly
quick with the shaft _c´_. To effect this variation, the cone is shifted
lengthwise along its shaft, while the band running upon it remains
continually in the same vertical plane, and is kept distended by the
weight of the pulley _o´_. The following mechanism serves to shift the
cone, which may be best understood by the aid of the figures 340., 341.,
and 337. A long cast iron bar _m_³, which bears two horizontal
projecting puppets, _o_³ _o_³, is made fast to the front upright face of
the copping beam A. Through the above puppets a cylindrical rod _n_³
passes freely, which is left out in _fig._ 337., that the parts lying
behind it may be better seen. Upon this rod there is a kind of fork,
_p_³ _p_³, to which the alternating rack bars _q_³ are made fast. The
teeth of these racks are at unequal distances from each other, and are
so arranged, that each tooth of the under side corresponds to the space
between two teeth in the upper side. Their number depends upon the
number of coils of roving that may be required to fill a bobbin; and
consists in the usual machines of from 20 to 22. The rod _n_³ may be
shifted in the puppet _o_³, like the fork _p_³ of the rack-rod, upon the
rod _n_³, and along the surface of _m_³, where two wings _u_³ _u_³ are
placed, to keep the fork in a straight direction. Upon the bar _m_³,
there are the pivots or fulcra of two stop catches _w_³ _x_³, of which
the uppermost presses merely by its own weight, but the undermost by
means of a counterweight _y_³, against the rack, and causes them thus to
fall in between the teeth. In _fig._ 341., _v_³ shows the pivot of the
catch or detent _w_³ by itself, the detent itself being omitted, to
render the construction plainer. A pushing rod _l_³, upon which there is
a pin above at _s_³, that passes behind the rack rod, between this and
the bar _m_³, has for its object to remove at pleasure the one or the
other of the two catches; the upper, when the upper end of the rod
pushes against it; the under, by means of the above mentioned pin _s_³.
Both the catches are never raised at once, but either the under or the
upper holds the rack bar fast, by pressing against one of the teeth. The
vertical motion up or down, which the rod _l_³ must take to effect the
lifting of the catches, is given to it from the copping beam _p_; since
upon it a horizontal arm _v_², _fig._ 341., is fixed, that lays hold of
that rod. Upon the pushing rod are two rings, _h_³ and _k_³, each made
fast by a screw. When the copping beam is in the act of going up, the
arm _v_³ at the end of this movement, pushes against the ring _h_³,
raises up the rod _l_³, and thus removes the catch _w_³, _fig._ 337.,
from the teeth of the rod _q_³, before which it lies flat. At the
descent of the copping rail, _v_² meets the ring _k_³, when the motion
in this direction is nearly completed, draws down the rod _l_³ a little,
by means of the same, and thereby effects the removal of the catch _x_³,
_fig._ 337., from the rod _q_³. Every time that one of the catches is
lifted, the rack recovers its freedom to advance a little bit in the
direction of the arrow; so far, namely, till the other catch lays hold
upon the tooth that next meets it. The reason is thus manifest why the
teeth of the upper and under sides of the bar _q_³ are not right
opposite to each other, but in an alternate position.

From the rack-bar, the sliding of the cone _k´_, and the raising of the
shaft _y_², each by minute steps at a time, is produced as follows:--

A large rectangular lever _t_¹, _v_¹, whose centre of motion is at _p_⁴,
has at the upper end of its long arm _t_¹, a long slot through which a
stud _r_³ upon the rack _q_³ goes (_fig._ 340., 341., 337.,) so that the
lever must follow the motions of the rack bar. The end of the short arm
of the lever bears, as already mentioned, the step of the shaft _y_²;
hence the friction disc _x_¹ will be raised in proportion as the rack
bar advances, and will come nearer to the middle point of _g_¹;
consequently, its revolution and the shifting of the bobbins will become
slower. Upon the cylindrical rod _n_³, the piece _s_¹ _s_¹ furnished
with a long slot is made fast, by means of a tube _z_³, (_fig._ 337.)
and a screw. A fork _u u_, which by means of the screw nut _a_⁴ is made
fast in the slot, embraces the arm _t_¹ of the bent lever; and a tube
_r_¹ rivetted to the surface of _s_¹, is destined to take up the draw
rod _q_¹ of the cone _k_¹, _fig._ 337. A weight _f_⁴, whose cord _b_⁴ is
made fast to the cylindrical rod _n_³, endeavours to draw this rod
continually in the direction of the arrow. In consequence of this
arrangement, every time that the pushing bar _l_³ lifts up one of the
catches, the cone _k_¹, the lever _t_¹ _v_¹, and by it the rack bar
_q_³, are set in motion. It is obvious, that the motion of the cone may
be made greater or less, according as the fork _u u_ is fixed further up
or down in the slot of _s_¹.

The number of the teeth upon the bar _q_³ is so ordered, that the
bobbins are quite full when the last tooth has reached the catch and is
released by it. The rack bar, being restrained by nothing, immediately
slides onwards, in consequence of the traction of the weight _f_⁴ and
brings the machine to repose by this very movement, for which purpose
the following construction is employed. A rectangular lever which has
its centre of motion in _g_⁴ is attached to the side face of the beam A,
and has at the end of its horizontal arm a pulley _d_⁴, over which the
cord _b_⁴ of the counterweight _f_⁴ is passed. The end of the
perpendicular arm is forked and embraces the long and thin rod _k_⁴, to
whose opposite end the fork _l_⁴ is made fast. Through this fork the
band which puts the machine in motion passes down to the pulley _a_¹.
With the bent lever another rod _c_⁴ is connected at _h_⁴, which lies
upon the puppet _e_³ with a slot at _e_⁴, and hereby keeps the lever
_g_⁴ in its upright position notwithstanding the weight _f_⁴. In the
moment when, as above stated, the rack bar _q_³ becomes free, the arm
_p_³ of its fork pushes in its rapid advance against the under oblique
side of _e_⁴, raises this rod, and thereby sets the lever _g_⁴ free,
whose upright arm bends down by the traction of the weight, drives the
rod _k_⁴ before it into the ring _i_⁴ fastened to it, and thus by means
of the fork _l_⁴ shifts the band upon the loose pulley _b_¹. But the
machine may be brought to repose or put out of geer at any time merely
by shifting the rod _k_⁴ with the hand.

The operation of the bobbin and fly frame may be fully understood from
the preceding description. A few observations remain to be made upon the
cone _k_¹, the rack-bar _q_³, and the speed of the work.

When we know the diameter of the empty bobbins, and how many turns they
should make in a given time in order to wind-on the sliver delivered by
the fluted rollers and the spindles; when we consider the diameters of
the spindle pullies _q_, and _t_², as also the drum. _m_¹, _fig._ 332.,
we may easily find the diameter which the cone must have for producing
that number of turns. This is the diameter for the greatest periphery of
the base. The diameter of the smaller is obtained in the same way, when
the diameter of the bobbins before the last winding-on, as well as the
number of turns necessary in a given time, are known.

A bobbin and fly frame of the construction just described delivers from
each spindle in a day of twelve hours, from 6 to 8 lbs of roving of the
fineness of 1-1/2 English counts. One person can superintend two frames,
piece the broken slivers, and replace the full bobbins by empty ones.
The loss of cotton wool in this machine consists in the portions carried
off from the torn slivers, and must be returned to the lapping machine.

_The fine bobbin and fly frame_ does not differ essentially from the
preceding machine. The rovings from the coarse bobbin and fly frame are
placed in their bobbins in a frame called the _creel_, behind and above
the roller beam, two bobbins being allowed for one fluted portion of the
rollers. These rovings are united into one, so as to increase the
uniformity of the slivers.

The invention of the beautiful machine above described is due to Messrs.
Cocker and Higgins of Manchester, and as lately improved by Henry
Houldsworth, junr. Esq., it may be considered the most ingeniously
combined apparatus in the whole range of productive industry.

In the fine roving frame the sliver is twisted in the contrary direction
to that of the coarse roving frame. For this reason the position of the
cone is reversed, so as to present in succession to the band or strap,
diameters continually greater, in order that the rotation of the bobbins
may be accelerated in proportion as their size is increased, because
here the flyer and the bobbin turn in the same direction, and the
winding-on is effected by the precession of the bobbin; but if the
winding-on took place by its falling behind, as in the coarse bobbin and
fly frame, that is, if the flyer turned less quickly than the bobbin,
the rotatory speed of the bobbin would be uniformly retarded; in which
case the cone would be disposed as in the coarse frame.

When by any means whatever an uniform length of thread is delivered by
the rollers in a given time, the bobbin must wind it up as it is given
out, and must therefore turn with a speed decreasing with the increase
of its diameter by successive layers of thread. Hence proceeds the
proposition, that the velocity of the bobbin must be in the inverse
ratio of its diameter, as already explained.

With respect to the bobbin and fly frame, the twist is given to the
sliver by means of a spindle or flyer which turns in the same direction
with the bobbin, but quicker or slower than it, which establishes two
predicaments. The first case is where the flyer turns faster than the
bobbin. Here the winding-on goes in advance, as in the coarse roving
frame, or as in throstle spinning, where the yarn is wound on merely in
consequence of the friction of the lower disc or washer of the bobbin
upon the copping rail, and of the drag of the yarn. The second case is
where the flyer revolves more slowly than the bobbin. Here the winding
goes on in arrear, and as the bobbin turns faster, it must receive a
peculiar motion, which is uniformly retarded in the ratio of its
increase of diameter. This is the case with the fine bobbin and fly
frame. When the cone is placed as in _fig._ 332, the winding-on, in
either the coarse or fine frame, results from the difference, whether
greater or less, between the rotatory speed of the flyer and bobbin.

The motion of the bobbin and spindle is simultaneous, and takes place in
the same direction, with a difference varying more or less with the
varying diameters of the bobbins. To render the matter still clearer,
suppose for a moment the spindle to be motionless, then the bobbin must
revolve with such a speed, as to lap-on the roving as fast as the
rollers deliver it. The sliver comes forward uniformly; but the bobbin,
by its increase of diameter, must revolve with a speed progressively
slower. Now, suppose the spindle set a-whirling, it is obvious that the
bobbin must add to the movement requisite for winding-on the sliver,
that of the spindle in the case of winding-on in arrear, or when it
follows the flyers, and subtract its own motion from the twisting motion
of the spindles, in the case of winding-on in advance, that is, when the
bobbin precedes or turns faster than the flyers; for the diameter of the
bobbin being 1-1/2 inch, 10 turns will take up 45 inches. Deducting
these 10 turns from the 30 made by the spindle in the same time, there
will remain for the effective movement of the bobbin only 20 turns; or
when the diameter of the bobbin becomes 3 inches, 5 turns will take up
the 45 inches, if the spindle be at rest; but if it makes 30 turns in
the time, the effective velocity of the bobbin will be 25 turns, = 30 -
5. Hence in the fine bobbin and fly frame, the number of turns of the
spindle, _minus_ the number of turns made by the bobbin in equal times,
is in the inverse ratio of the diameter of the bobbin. We thus perceive,
that in the coarse frame the bobbin should move faster than the spindle,
and that its speed should always diminish; whilst in the fine frame the
bobbin should move slower than the spindle, but its speed should always
increase. It is easy to conceive, therefore, why the cones are placed in
reverse directions in the two machines. Not that this inversion is
indispensably necessary; the cone of the fine roving frame might, in
fact, be placed like that of the coarse roving frame; but as the torsion
of the roving becomes now considerable, and as on that account the
bobbin would need to move still faster, which would consume a greater
quantity of the moving power, it has been deemed more economical to give
its movement an opposite direction.

We mentioned that the twist of the sliver in the fine roving frame was
the reverse of that in the coarse; this is a habit of the spinners, for
which no good reason has been given.

The divisions of the rack-bar, and the successive diameters of the cone,
must be nicely adjusted to each other. The first thing to determine is
how much the rack should advance for every layer or range of roving
applied to the bobbin, in order that the cone may occupy such a place
that the strap which regulates the pulley barrel may be at the proper
diameter, and thus fulfil every condition. The extent of this
progressive movement of the rack depends upon the greater or less taper
of the cone, and the increase which the diameter of the bobbin receives
with every traverse, that is, every layer of roving laid on. But care
should be taken not to taper the cone too rapidly, especially in the
fine roving frame, because in its progress towards the smaller end, the
strap would not slide with certainty and ease. We have already shown
that the number of effective turns of the bobbin is inversely, as the
diameter of the bobbin, or directly, as the successive diameters of the
different points of the cone.

H. Houldsworth, jun. Esq. has introduced a capital improvement into the
bobbin and fly frame, by his differential or equation-box mechanism, and
by his spring fingers, which, by pressing the soft sliver upon the
bobbin, cause at least a double quantity to be wound upon its barrel.
With the description of his patent equation-box, I shall conclude the
description of the bobbin and fly frame.

_Fig._ 342. represents a portion of a fly frame with Mr. Houldsworth’s
invention. _a a a_ are the front drawing rollers, turning upon bearings
in the top of the machine, and worked by a train of toothed wheels, in
the way that drawing rollers are usually actuated.

From the drawing rollers, the filaments of cotton or other material, _b
b_, are brought down to, and passed through the arms of the flyers _c
c_, mounted on the tops of the spindles _d d_, which spindles also carry
the loose bobbins _e e_. In the ordinary mode of constructing such
machines, the spindles are turned by cords or bands passing from a
rotatory drum round their respective pulleys or whirls _f_, and the
loose bobbins _e_, turn with them by the friction of their slight
contact to the spindle, as before said; in the improved machine,
however, the movements of the spindles and the bobbins are independent
and distinct from each other, being actuated from different sources.

The main shaft of the engine _g_, turned by a band and rigger A as
usual, communicates motion by a train of wheels _h_, through the shaft
_i_, to the drawing rollers at the reverse end of the machine, and
causes them to deliver the filaments to be twisted. Upon the main shaft
_g_, is mounted a cylindrical hollow box or drum-pulley, whence one cord
passes to drive the whirls and spindles _f_ and _d_, and another to
drive the bobbins _e_.

[Illustration: 342 343 344]

This cylindrical box pulley is made in two parts, _k_ and _l_, and
slipped upon the axle with a toothed wheel _m_, intervening between
them. The box and wheel are shewn detached in _fig._ 343., and partly in
section at _fig._ 344. That portion of the box with its pulley marked
_l_, is fixed to the shaft _g_; but the other part of the box and its
pulley _k_, and the toothed wheel _m_, slide loosely round upon the
shaft _g_, and when brought in contact and confined by a fixed collar
_n_, as in the machine shewn at _fig._ 342., they constitute two
distinct pullies, one being intended to actuate the spindles, and the
other the bobbins.

In the web of the wheel _m_, a small bevel pinion _o_, is mounted upon
an axle standing at right angles to the shaft _g_, which pinion is
intended to take into the two bevel pinions _p_ and _q_, respectively
fixed upon bosses, embracing the shaft in the interior of the boxes _k_
and _l_. Now it being remembered that the pinion _q_, and its box _l_,
are fixed to the shaft _g_, and turn with it, if the loose wheel _m_ be
independently turned upon the shaft, with a different velocity, its
pinion _o_, taking into _q_, will be made to revolve upon its axle, and
to drive the pinion _p_, and pulley box _k_, in the same direction as
the wheel _m_; and this rotatory movement of the box _k_ and wheel _m_,
may be faster or slower than the shaft _g_, and box _l_, according to
the velocity with which the wheel _m_ is turned.

Having explained the construction of the box pullies _k_ and _l_, which
are the peculiar features of novelty claimed under this patent, their
office and advantage will be seen by describing the general movements of
the machine.

The main shaft _g_, being turned by the band and rigger A, as above
said, the train of wheels _h_, connected with it, drives the shaft _i_,
which at its reverse end has a pinion (not seen in the figure,) that
actuates the whole series of drawing rollers _a_. Upon the shaft _i_
there is a sliding pulley _r_, carrying a band _s_, which passes down to
a tension pulley _t_, and is kept distended by a weight. This band _s_,
in its descent, comes in contact with the surface of the cone _u_, and
causes the cone to revolve by the friction of the band running against
it. The pulley _r_ is progressively slidden along the shaft _i_, by
means of a rack and weight not shewn, but well understood as common in
these kind of machines, and which movement of the pulley is for the
purpose of progressively shifting the band _s_ from the smaller to the
larger diameter of the cone, in order that the speed of its rotation may
gradually diminish as the bobbins fill by the winding-on of the yarns.

At the end of the axle of the cone _u_ a small pinion _v_ is fixed,
which takes into the teeth of the loose wheel _m_, and, as the cone
turns, drives the wheel _m_ round upon the shaft _g_, with a speed
dependent always upon the rapidity of the rotation of the cone. Now the
box pulley _l_, being fixed to the main shaft _g_, turns with one
uniform speed, and by cords passing from it over guides to the whorls
_f_, drives all the spindles and flyers, which twist the yarns with one
continued uniform velocity; but the box pulley _k_, being loose upon
the shaft, and actuated by the bevel pinions within, as described, is
made to revolve by the rotation of the wheel _m_, independent of the
shaft, and with a different speed from the pulley box _l_; cords passing
from this pulley box _k_, over guides to small pullies under the
bobbins, communicate the motion, whatever it may be, of the pulley box
_k_, to the bobbins, and cause them to turn, and to take up or wind the
yarn with a speed derived from this source, independent of, and
different from, the speed of the spindle and flyer which twist the yarn.

It will now be perceived, that these parts being all adjusted to
accommodate the taking up movements to the twisting or spinning of any
particular quality of yarn intended to be produced, any variations
between the velocities of the spinning and taking up, which another
quality of yarn may require, can easily be effected, by merely changing
the pinion _v_, for one with a different number of teeth, which will
cause the wheel _m_, and the pulley box _k_, to drive the bobbins faster
or slower, as would be required in winding-on fine or coarse yarn, the
speed of the twisting or spinning being the same.

The rovings or spongy cords, of greater or less tenuity, made on the
bobbin and fly, or tube roving frame, are either spun immediately into
firm cohesive yarn, or receive a further preparation process in the
stretching frame, which is, in fact, merely a mule-jenny, without the
second draught and second speed, and therefore need not be described at
present, as it will be in its place afterwards.

The _finishing machines_ of a cotton mill, which spin the cohesive yarn,
are of two classes; 1. the water-twist or throstle, in which the
twisting and winding are performed simultaneously upon progressive
portions of the roving; and, 2. the mule, in which the thread is drawn
out and stretched, with little twist, till a certain length of about 5
feet is extended, then the torsion is completed, and the finished thread
is immediately wound upon the spindles into double conical coils called
cops.

[Illustration: 345]

The water-twist frame, so called by its inventor, Sir R. Arkwright,
because it was first driven by water, is now generally superseded by the
throstle frame, in which the mechanical spinning fingers, so to speak,
are essentially the same, but the mode of communicating the motion of
the mill-geering to them is somewhat different. _Fig._ 345. exhibits a
vertical section of the throstle. This machine is double, possessing
upon each side of its frame, a row of spindles with all their subsidiary
parts. The bobbins, filled with rovings from the bobbin and fly, or the
tube frame, are set up in the creel _a a_, in two ranges, _b_, _c_, _d_,
are the three usual pairs of drawing rollers, through which the yarn is
attenuated to the proper degree of fineness, upon the principles already
explained. At its escape from the front rollers, every thread runs
through a guide eyelet _e_ of wire, which gives it the vertical
direction down towards the spindles _f_, _g_. The spindles which perform
at once and uninterruptedly the twisting and winding-on of the thread
delivered by the rollers, are usually made of steel, and tempered at
their lower ends. They stand at _g_ in steps, pass at _v_ through a
brass bush or collet which keeps them upright, and revolve with
remarkable speed upon their axes. The bobbins _h_, destined to take up
the yarn as it is spun, are stuck loosely upon the spindles, and rest
independently of the rotation of the spindles upon the copping beam _l_,
with a leather washer between. Upon the top of the spindles an iron-wire
fork, called a fly or flyer, _i_, _k_, is made fast by a left-hand
screw, and has one of its forks turned round at the end into a little
ring. The branch of the flyer at _f_ is tubular, to allow the thread to
pass through, and to escape by a little hole at its side, in order to
reach the eyelet at the end of that fork. From this eyelet _i_, it
proceeds directly to the bobbin. By the twirling of the spindle, the
twisting of the portion of thread between the front roller _d_, and the
nozzle _f_, is effected. The winding-on takes place in the following
way:--Since the bobbin has no other connection with the spindle than
that of the thread, it would but for it remain entirely motionless,
relatively to the spindle. But the bobbin is pulled after it by the
thread, so that it must follow the rotation of the spindle and fly. When
we consider that the thread is pinched by the front roller _d_, and is
thereby kept fully upon the stretch, we perceive that the rotation of
the bobbin must be the result. Suppose now the tension to be suspended
for an instant, while the rollers _d_, deliver, for example, one inch of
yarn. The inertia or weight of the bobbin, and its friction upon the
copping beam _l_, by means of the leather washer, will, under this
circumstance, cause the bobbin to hang back in a state of rest, till the
said inch of yarn be wound on by the whirling of the fly _i_, and the
former tension be restored. The delivery of the yarn by the drawing
rollers, however, does not take place inch after inch, by starts, but at
a certain continuous rate; whence results a continuous retardation or
loitering, so to speak, of the bobbins behind the spindles, just to such
an amount that the delivered yarn is wound up at the same time during
the rotation.

This process in spinning is essentially the same as what occurs in the
fine bobbin and fly frame, but is here simplified, as the retardation
regulates itself according to the diameter of the bobbin by the drag of
the thread. In the fly frame the employment of this tension is
impossible, because the roving has too little cohesion to bear the
strain; and hence it is necessary to give the bobbins that independent
movement of rotation which so complicates this machine.

The up and down motion of the bobbins along the spindles, which is
required for the equal distribution of the yarn, and must have the same
range as the length of the bobbin barrels, is performed by the following
mechanism. Every copping rail _l_, is made fast to a bar _m_, and this,
which slides in a vertical groove or slot at the end of the frame, is
connected by a rod _n_, with an equal-armed, moveable lever _o_. The rod
_p_ carries a weight _r_, suspended from this lever; another rod _q_,
connects the great lever _o_ with a smaller one _s_, _t_, upon which a
heart-shaped disc or pulley _u_, works from below at _t_. By the
rotation of the disc _u_, the arm _t_, being pressed constantly down
upon it by the reaction, the weight _r_ must alternately rise and fall;
and thus the copping rail _l_ must obviously move with the bobbins _h_
up and down; the bobbins upon one side of the frame rising, as those
upon the other sink. Strictly considered, this copping motion should
become slower as the winding-on proceeds, as in the fly roving frame;
but, on account of the smallness of the finished thread, this
construction, which would render the machine complicated, is without
inconvenience neglected, with the result merely that the coils of the
yarn are successively more sparsely laid on, as the diameter of the
bobbin increases.

The movement of the whole machine proceeds from the shaft of a
horizontal drum, which drives the spindles by means of the endless bands
_x x_. Each spindle is mounted with a small pulley or wharf _w_, at its
lower part, and a particular band, which goes round that wharf or whorl,
and the drum _y_. The bands are not drawn tense, but hang down in a
somewhat slanting direction, being kept distended only by their own
weight. Thus every spindle, when its thread breaks, can readily be stopt
alone, by applying a slight pressure with the hand or knee, the band
meanwhile gliding loosely round the whorl.

The velocities of rotation of the three drawing rollers are, according
to this arrangement, in the proportion of 1 : 1-1/2 : 8; and as their
diameters are the same, namely, one inch, the elongation of the yarn in
spinning is eight-fold. If, for example, the roving was of the number
4-1/2, the yarn would become No. 36. The extension of the thread may be
changed by changing the wheels of the drawing rollers. To perceive the
power of this change, let us put, for example, in the place of the
18-toothed wheel of the back rollers, a wheel with 16 teeth; we shall
find that the elongation will amount, in that case, only to 7-1/2 times,
whence the number of the yarn would come out 32 = 7-1/2 × 4-1/2. The
extension by the throstle is extremely various; it amounts, in some
cases, to only 4 times; at others to 10, 12, or even 15.

The copping motion of the bobbins is produced in consequence of a bevel
pinion working in a small bevel wheel upon an upright shaft; while this
wheel gives a slow motion by means of a worm screw to the wheel of the
heart-shaped pulley _u_, _fig._ 345.

The driving pulley makes about 600 turns in a minute; and as the
diameter of the drum _y_, _fig._ 345., is six times the diameter of the
spindle wharves _w_, it will give 3600 turns to the spindle in that
time. If the pulley be driven faster, for example 700 times in a minute,
it will increase the revolutions of the spindles to 4200. The degree of
twist which will be thereby imparted to the yarn, depends, with like
speed of spindles, upon the rate at which the soft yarn is delivered by
the drawing rollers; for the quicker this delivery, the quicker is the
winding-on, and the less twist goes into a given length of yarn. If, for
example, the front rollers _d_, turn 24 times in a minute, giving out of
course 72 inches of yarn in this time, upon which the 3600 revolutions
of the spindle are expended, there will be 50 twists to every inch of
yarn. By changing the wheel-work of _fig._ 345., or by sticking greater
or smaller wharves upon the spindles, the proportion between their
velocity and that of the drawing rollers, and thence the degree of twist
can be modified at pleasure.

The number of spindles in a throstle frame 12 feet long, is about 60 on
each side. The drawing rollers are coupled together as in the bobbin and
fly frame, so that each row forms one continuous cylinder. There is a
complete roller beam on each side; each of the rollers of the front row
is pressed by its top rollers with a weight of ten or twelve pounds;
but those of the middle and back rows bear weights of only one pound. In
the throstles, there is a guide bar which traverses a small way
horizontally to the left and right, in front of the roller beam, to lead
the thread along different points of the rollers, and thus prevent the
leather of the top ones from being grooved by its constant pressure in
one line.

For the service of 240 spindles, in two double frames, one young woman,
and an assistant piecer are sufficient. They mend the broken ends, and
replace the empty bobbins in the creel with full ones, and the full
bobbins of the throstle by empty ones. The average quantity of yarn
turned off in a week of 69 hours is about 24 hanks per spindle of 30´s
twist. Throstle yarn is of a firm wiry quality, adapted to the warps of
fustians and other strong stuffs, as well as to the manufacture of
stockings and sewing thread.

There are many modifications of the throstle system besides the one
above described; the most celebrated of which are Danforth’s, called the
American throstle, Montgomery’s, and Gore’s. I must refer for an account
of them to my work entitled “The Cotton Manufacture of Great Britain,”
where they are minutely described and illustrated with accurate figures.

_Mule-spinning._--The general principles of the mule have been already
stated. This machine is so named because it is the offspring, so to
speak, of two older machines, the jenny and the water-frame. A mule is
mounted with from 240 to 1000 spindles, and spins of course as many
threads.

[Illustration: 346]

_Fig._ 346. represents the original _jenny_ of Hargreaves, by which one
person was enabled to spin from 16 to 40 threads at once. The soft cords
of rovings wound in double conical cops upon skewers were placed in the
inclined frame at C; the spindles for first twisting and then winding-on
the spun yarn were set upright in steps and bushes at A, being furnished
near their lower ends with whorls, and endless cords, which were driven
by passing round the long-revolving drum of tin plate E. D is the clasp
or clove, having a handle for lifting its upper jaw a little way, in
order to allow a few inches of the soft roving to be introduced. The
compound clove D being now pushed forward upon its friction wheels to A,
was next gradually drawn backward, while the spindles were made to
revolve with proper speed by the right hand of the operative turning the
flywheel B. Whenever one _stretch_ was thereby spun, the clove frame was
slid home towards A; the spindles being simultaneously whirled slowly to
take up the yarn, which was laid on in a conical cop by the due
depression of the faller wire at A with the spinner’s left hand.

[Illustration: 347]

_Fig._ 347. is a diagram of Arkwright’s original _water-frame_ spinning
machine, called afterwards the _water-twist frame_. The rovings mounted
upon bobbins in the creel A A, have their ends led through between the
three sets of twin rollers below B B, thence down through the eyelet
hooks upon the end of the flyers of the spindles C, and finally attached
to their bobbins. The spindles being driven by the band D D upon their
lower part, continuously twist and wind the finished yarn upon the
bobbins; constituting the first unremitting automatic machine for
spinning which the world ever saw.

[Illustration: 348]

Contrast with the above admirable system, the primitive cotton wheel of
India, as represented in the annexed figure 348. By the aid of
mechanical fingers, one Englishman at his mule can turn off daily more
yarn and of far finer quality than 200 of the most diligent spinsters of
Hindostan.

[Illustration: 349]

_Fig._ 349., is a transverse section of the mule, in which its principal
parts are shown.

The machine consists of two main parts; a fixed one corresponding in
some measure to the water-frame or throstle, and a moveable one
corresponding to the jenny. The first contains in a suitable frame the
drawing roller-beam and the chief moving machinery: the second, is
called the carriage, in which the remainder of the moving mechanism and
the spindles are mounted.

The frame of the fixed part consists of two upright sides, and two or
more intermediate parallel bearings, upon which the horizontal roller
beam _a_, the basis of the drawing rollers is supported, _b_, _c_, _d_,
are the three ranges of fluted iron rollers; _e_, _f_, _g_, are the
upper iron rollers covered with leather; _h_, the wooden wiper-rollers
covered with flannel, which being occasionally rubbed with chalk,
imparts some of it to the pressure rollers beneath, so as to prevent the
cotton filaments adhering to them. The rollers are made throughout the
whole length of the mule in portions containing six flutings, which are
coupled together by squared ends fitted into square holes.

The skewers upon which the bobbins containing the rovings from the
bobbin and fly or stretching frame, are set up, are seen at _a_¹, _a_¹,
_a_¹, arranged in three rows in the creel _z_. The soft threads unwound
from these bobbins, in their way to the drawing rollers, pass first
through eyelets in the ends of the wire arms _b_¹, then through the
rings or eyes of the guide bar _w_, and enter between the back pair of
rollers. The number of these bobbins is equal to the number of spindles
in the mule, and twice as great as the number of fluted portions of the
rollers; for two threads are assigned to each portion.

The carriage consists of two cast-iron side pieces, and several
cast-iron intermediate similar pieces, such as _f_², which all together
are made fast to the planks _b_², _c_², _d_². The top is covered in with
the plank _k_². The carriage runs by means of its cast-iron grooved
wheels, upon the cast-iron railway _l_², which is fixed level on the
floor.

The spindles stand upon the carriage in a frame, which consists of two
slant rails _x_², _x_², connected by two slender rods _y_², and which
frame may be set more or less obliquely. The lower rail carries the
brass steps for the points of the spindles _b_³; upon the upper rail
brass slips are fixed pierced with holes through which the tops of the
spindles play. The spindles are as usual made of steel, perfectly
straight, turned truly round, and are all arranged in one plane. To each
of them a small wooden or cast-iron whorl _g_² is made fast. They are
distributed into groups of 24, and the whorls are arranged at such
different heights, that only two of them in each group are upon a level
with each other. A small brass head _h_², which every spindle has
beneath the upper slant rail of the frame _x_², prevents their sitting
down into the step, during their rotation, or sliding off their cop of
yarn.

_c_³ are drums, mounted in the carriage in a plane at right angles to
the plane in which the spindles are placed. At top they have a double
groove for a cord to run in, and the motion which they receive from the
great fly wheel, or rim of the mule (not visible in this view) they
impart to the spindles. Such a drum is assigned to every 24 spindles;
and therefore a mule of 480 spindles contains 20 drums. In the middle of
the carriage is seen the horizontal pulley _k_³, furnished with three
grooves, which stands in a line with the drums _c_³.

The motion is given to the drums _c_³, upon the right hand half of the
carriage by a single endless band or cord which proceeds from the middle
groove of the pulley _k_³. The rotation of the spindles is produced by a
slender cord, of which there are 12 upon each drum _c_³; because every
such cord goes round the drum, and also every two wharves which stand at
the same level upon the spindles. It is obvious that the drums, and
consequently the spindles, must continue to revolve as long as the main
rim of the mule is turned, whether the carriage be at rest or in motion
upon its railway.

If we suppose the carriage to be run in to its standing point, or to be
pushed home to the spot from which it starts in spinning, its back plank
_d_² will strike the post _q_³ upon the fixed frame, and the points of
the spindles will be close in front of the roller beam. The rollers now
begin to turn and to deliver threads, which receive immediately a
portion of their twist from the spindles; the carriage retires from the
roller beam with somewhat greater speed than the surface speed of the
front rollers, whereby the threads receive a certain degree of
stretching, which affects most their thicker and less twisted portions,
and thereby contributes greatly to the levelness of the yarn. When the
carriage has run out to the end of its course, or has completed a
stretch, the fluted rollers suddenly cease to revolve (and sometimes
even beforehand, when a second stretch is to be made), but the spindles
continue to whirl till the fully extended threads have received the
proper seconder after-twist. Then the carriage must be put up, or run
back towards the rollers, and the threads must be wound upon the
spindles.

This is the order of movements which belong to the mule. It has been
shown how the rotation of the spindles is produced.

For winding-on the yarn the carriage has a peculiar apparatus, which we
shall now describe. In front of it, through the whole extent to the
right hand as well as the left, a slender iron rod, _d_⁵, runs
horizontally along, in a line somewhat higher than the middle of the
copping portion of the spindles, and is supported by several props, such
as _e_⁵. Upon each end of the two rods, _d_⁵, there is an arm, _g_⁵; and
betwixt these arms an iron wire, called the copping wire, _f_⁵, is
stretched, parallel with the rod _d_⁵. For the support of this wire,
there are several slender bent arms _h_⁵ extended from the rod _d_⁵ at
several points betwixt the straight arms _g_⁵. The rod _d_⁵ has, besides
a wooden handle at the place opposite to where the spinner stands, by
which it can be readily grasped. This movement is applied at the left
division of the machine, and it is communicated to the right by an
apparatus which resembles a crane’s bill. The two arms, _g_⁵, in the
middle of the machine, project over the rods _d_⁵, and are connected by
hinges with two vertical rods _j_⁵, which hang together downwards in
like manner with two arms _i_⁵, proceeding from a horizontal axis _k_⁵.

By means of that apparatus the yarn is wound upon the spindles in the
following manner. As long as the stretching and twisting go on, the
threads form an obtuse angle with the spindles, and thereby slide
continually over their smooth rounded tips during their revolution,
without the possibility of coiling upon them. When, however, the
spinning process is completed, the spinner seizes the carriage with his
left hand and pushes it back towards the roller beam, while with his
right hand he turns round the handle of the rim or fly wheel, and
consequently the spindles. At the same time, by means of the handle upon
the rod _d_⁵, he moves the copping-wire, _f_⁵, so that it presses down
all the threads at once, and places them in a direction nearly
perpendicular to the spindles; as shown by the dotted line _y_⁵. That
this movement of the copping wire, however, may take place without
injury to the yarn, it is necessary to turn the rim beforehand a little
in the opposite direction, so that the threads may get uncoiled from the
upper part of the spindles, and become slack; an operation called in
technical language, the _backing off_. The range upon which the threads
should be wound, in order to form a conical cop upon the spindle, is hit
by depressing the copping wire to various angles, nicely graduated by an
experienced eye. This faller wire alone is not, however, sufficient for
the purpose of winding-on a seemly cop, as there are always some loose
threads which it cannot reach without breaking others.

Another wire called the _counter-faller_, _l_⁵, must be applied under
the threads. It may be raised to an elevation limited by the angular
piece _p_⁵; and is counterpoised by a very light weight _m_⁵, applied
through the bent lever _n_⁵, which turns upon the fulcrum _o_⁵. This
wire, which applies but a gentle pressure, gives tension to all the
threads, and brings them regularly into the height and range of the
faller _f_⁵. This wire must be raised once more, whenever the carriage
approaches the roller beam. At this instant a new stretch commences; the
rollers begin again to revolve, and the carriage resumes its former
course. These motions are performed by the automatic machinery.

There is a little eccentric pulley mechanism for moving the guide beam
to and fro with the soft yarns, as they enter between the back rollers.
On the right hand end of the back roller shaft, a worm screw is formed
which works into the oblique teeth of a pinion attached to the end of
the guide beam, in which there is a series of holes for the passage of
the threads, two threads being assigned to each fluted roller. In the
flat disc of the pinion, an eccentric pin stands up which takes into the
jointed lever upon the end of the guide beam, and as it revolves, pushes
that beam alternately to the left and the right by a space equal to its
eccentricity. This motion is exceedingly slow, since for each revolution
of the back roller, the pinion advances only by one tooth out of the 33
which are cut in its circumference.

After counting the number of teeth in the different wheels and pinions
of the mule, or measuring their relative diameters, it is easy to
compute the extension and twist of the yarns; and when the last fineness
is given to ascertain their marketable value. Let the ratio of speed
between the three drawing rollers be 1 : 1-3/22 : 7-1/2; and the
diameter of the back and middle roller three quarters of an inch: that
of the front roller one inch; in which case the drawing is thereby
increased 1-1/3 times, and 7-1/2 × 1-1/3 = 10. If the rovings in the
creel bobbins have been No. 4. the yarn, after passing through the
rollers, will be No. 40. By altering the change pinion (not visible in
this view) the fineness may be changed within certain limits, by
altering the relative speed of the rollers. For one revolution of the
great rim or fly wheel of the mule, the front roller makes about
6-tenths of a turn, and delivers therefore 22·6 lines or 12ths of an
inch of yarn, which, in consequence of the tenfold draught through the
rollers, corresponds to 2·26 lines of roving fed in at the back rollers.
The spindles or their whorls make about 66 revolutions for one turn of
the rim. The pulleys or grooved wheels on which the carriage runs,
perform 0·107 part of a turn while the rim makes one revolution, and
move the carriage 24·1 lines upon its rails, the wheels being 6 inches
in diameter.

The 22·6 lines of soft yarn delivered by the front rollers, will be
stretched 1-1/2 lines by the carriage advancing 24·1 lines in the same
time. Let the length of the railway, or of each stretch be 5 feet, the
carriage will complete its course after 30 revolutions of the rim wheel,
and the 5 feet length of yarn (of which 56-1/2 inches issue from the
drawing rollers, and 3-1/2 inches proceed from the stretching) is, by
the simultaneous whirling of the spindles, twisted 1980 times, being at
the rate of 33 twists for every inch. The second twist, which the
threads receive after the carriage has come to repose, is regulated
according to the quality of the cotton wool, and the purpose for which
the yarn is spun. For warp yarn of No. 40 or 50, for example, 6 or 8
turns of the rim wheel, that is, from 396 to 528 whirls of the spindles
for the whole stretch, therefore from 7 to 9 twists per inch will be
sufficient. The finished yarn thus receives from 40 to 42 twists per
inch.

One spinner attends to two mules, which face each other, so that he
needs merely turn round in the spot where he stands, to find himself in
the proper position for the other mule. For this reason the rim wheel
and handle, by which he operates, are not placed in the middle of the
length of the machine, but about two fifths of the spindles are to the
right hand and three fifths to the left; the rim wheel being towards his
right hand. The carriage of the one mule is in the act of going out and
spinning, while that of the other is finishing its twist, and being put
up by the spinner.

The quantity of yarn manufactured by a mule in a given time, depends
directly upon the number of the spindles, and upon the time taken to
complete every stretch of the carriage. Many circumstances have an
indirect influence upon that quantity, and particularly the degree of
skill possessed by the spinner. The better the machine, the steadier and
softer all its parts revolve, the better and more abundant is its
production. When the toothed wheels do not work truly into their
pinions, when the spindles shake in their bushes, or are not accurately
made, many threads break, and the work is much injured and retarded. The
better the staple of the cotton wool, and the more careful has been its
preparation in the carding, drawing, and roving processes, the more easy
and excellent the spinning will become: warmth, dryness, cold, and
moisture have great influence on the ductility, so to speak, of cotton.
A temperature of 65° F., with an atmosphere not too arid, is found most
suitable to the operations of a spinning mill. The finer the yarn, the
slower is the spinning. For numbers from 20 to 36, from 2 to 3 stretches
of warp may be made in a minute, and nearly 3 stretches of weft; for
numbers above 50 up to 100, about 2 stretches; and for numbers from 100
to 150, one stretch in the minute. Still finer yarns are spun more
slowly, which is not wonderful, since in the fine spinning mills of
England, the mules usually contain upwards of 500 spindles each, in
order that one operative may manage a great number of them, and thereby
earn such high wages as shall fully remunerate his assiduity and skill.

In spinning fine numbers, the second speed is given before the carriage
is run out to the end of its railway; during which course of about six
inches, it is made to move very slowly. This is called the second
stretch, and is of use in making the yarn level by drawing down the
thicker parts of it, which take on the twist less readily than the
thinner, and therefore remain softer and more extensible. The stretch
may therefore be divided into three stages. The carriage first moves
steadily out for about 4 feet, while the drawing rollers and spindles
are in full play; now the rollers stop, but the spindles go on whirling
with accelerated speed, and the carriage advances slowly, about 6 inches
more; then it also comes to rest, while the spindles continue to revolve
for a little longer, to give the final degree of twist. The acceleration
of the spindles in the second and third stages, which has no other
object but to save time, is effected by a mechanism called the
_counter_, which shifts the driving band, at the proper time, upon the
loose pulley, and, moreover, a second band, which had, till now, lain
upon its loose pulley, upon a small driving pulley of the rim-shaft. At
length, both bands are shifted upon their loose pulleys, and the mule
comes to a state of quiescence.

The SELF-ACTOR MULE, or the IRON MAN, as it has been called in
Lancashire, is an invention to which the combinations among the
operative spinners obliged the masters to have recourse. It now spins
good yarn up to 40 s with great uniformity and promptitude, and requires
only juvenile hands to conduct it, to piece the broken yarns, to replace
the bobbins of rovings in the creel, and to remove the finished cops
from the spindles.

The self-acting mules were first constructed, I believe, by Messrs.
Eaton, formerly of Manchester, who mounted ten or twelve of them in that
town, four at Wiln, in Derbyshire, and a few in France. From their great
complexity and small productiveness, the whole were soon relinquished,
except those at Wiln. M. de Jong obtained two patents for self-acting
mules, and put twelve of them in operation in a mill at Warrington, of
which he was part proprietor; but with an unsuccessful result. I saw the
_débris_ of one of M. de Jong’s self-actors in the factory of M. Nicolas
Schlumberger, at Guebwiller, in Alsace, where the machine had been
worked for three months, without advantage, under the care of the
inventor, who is a native of that valley.

The first approximation to a successful accomplishment of the objects in
view, was an invention of a self-acting mule, by Mr. Roberts, of
Manchester; one of the principal points of which was the mode of
governing the winding-on of the yarn into the form of a cop; the entire
novelty and great ingenuity of which invention was universally admitted,
and proved the main step to the final accomplishment of what had so long
been a desideratum. For that invention a patent was obtained in 1825,
and several headstocks upon the principle were made, which are still
working successfully.

In 1830, Mr. Roberts obtained a patent for the invention of certain
improvements; and by a combination of both his inventions, he produced a
self-acting mule, which is generally admitted to have exceeded the most
sanguine expectations, and which has been extensively adopted. There
are, probably, at present, upwards of half a million of spindles of
Messrs. Sharp, Roberts, and Co.’s construction, at work in the United
Kingdom, and giving great satisfaction to their possessors. The
advantages of these self-actors are the following:--

The saving of a spinner’s wages to each pair of mules, piecers only
being required, as one overlooker is sufficient to manage six or eight
pairs of mules. The production of a greater quantity of yarn, in the
ratio of from 15 to 20 per cent. The yarn possesses a more uniform
degree of twist, and is not liable to be strained during the spinning,
or in winding-on, to form the cop; consequently fewer threads are broken
in these processes, and the yarn, from having fewer piecings is more
regular.

The cops are made firmer, of better shape, and with undeviating
uniformity; and, from being more regularly and firmly wound, contain
from one third to one half more yarn than cops of equal bulk wound by
hand; they are consequently less liable to injury in packing or in
carriage, and the expense of packages and freight (when charged by
measurement) is considerably reduced.

From the cops being more regularly and firmly wound, combined with their
superior formation, the yarn intended for warps less frequently breaks
in winding or reeling, consequently there is a considerable saving of
waste in those processes.

Secondly, the advantages connected with weaving.

The cops being more regularly and firmly wound, the yarn, when used as
weft, seldom breaks in weaving; and as the cops also contain a greater
quantity of weft, there are fewer bottoms, consequently there is a very
material saving of waste in the process of weaving.

From those combined circumstances, the quality of the cloth is improved,
by being more free from defects caused by the breakage of the warp or
weft, as well as the selvages being more regular.

The looms can also be worked at greater speed; and, from there being
fewer stoppages, a greater quantity of cloth may be produced.

That the advantages thus enumerated, as derivable from the use of
self-acting mules, have not been overrated, but, in many instances, have
been considerably exceeded, I have, by extensive personal inquiry and
observation, had ample opportunity of ascertaining.

Statement of the quantity of yarn produced on Messrs. Sharp, Roberts,
and Co.’s self-acting mules, in twelve working hours, including the
usual stoppages connected with spinning, estimated on the average of
upwards of twenty mills:--

  No. of Yarn.   No. of Twist.         No. of Weft.
       16         4-1/2 hanks     4-7/8 hanks per spindle.
       24         4-1/4  --       4-5/8       --
       32         4      --       4-3/8       --
       40         3-3/4  --       4-1/8       --

Of the intermediate numbers the quantities are proportionate.

Results of trials made by Messrs. Sharp, Roberts, and Co., at various
mills, to ascertain the comparative power required to work self-acting
mules, in reference to hand-mules, during the spinning, up to the period
of backing off.

Particulars of the trials referred to, and their results:--

  +--------------------------+--------+-----+-------+-------+----------+
  |At what Mill, and the Des-|No. and |Dia- | Revo- |  Re-  |  Total   |
  |     cription of Mule.    |kind of |meter|lutions|quired |  Force   |
  |                          | Yarn.  |  of Pulley  |Force  | Employed |
  |                          |        |     or      | for   |    in    |
  |                          |        |  Rim Wheel. |Motion.| Spinning.|
  +--------------------------+--------+------+------+-------+----------+
  |_Messrs. Birley and Kirk._|_Weft._ |_Ins._|      | _lbs._|    _lbs._|
  |Self-acting mule, 360 sps.|30 to 34|  12  |  58  | 30    |     5463 |
  |[20]Hand mule, 180 sps.   | ditto  |  15  |  36  | 26    |     3669}|
  |                          |        |      |      |       |× 2 =7338}|
  |_Messrs. Leech and        |        |      |      |       |          |
  |Vandrey._                 |_Twist._|      |      |       |          |
  |[21]Self-acting mule, 324 |   36   |  12  |  70  | 36    |     7912 |
  |sps.                      |        |      |      |       |          |
  |Hand mules, 324 sps.      |   36   |  29  |  58  | 16-1/2|     7273 |
  |                          |        |      |      |       |          |
  |_Messrs. Duckworth & Co._ |_Twist._|      |      |       |          |
  |Self-acting mule, 324 sps.|   40   |  12  |  62  | 33    |     6421 |
  |Hand mule, 324 sps.       |   40   |  47  |  36  | 15-1/2|     6646 |
  +--------------------------+--------+------+------+-------+----------+

  [20] The trial was disadvantageous for the hand-mules, being two for
  360 spindles.

  [21] The trial was disadvantageous for the self-acting mules, being
  driven by a very short and light vertical strap, the hand-mule having
  a long horizontal strap.

The mode adopted to make the trials was as follows, viz.:

A force, indicated by weight in pounds, was applied to the strap working
upon the driving-pulley of the respective mules, sufficient to maintain
the motion of the mule whilst spinning, which weight, being multiplied
by the length of strap delivered by each revolution of the pulley, and
again by the number of revolutions made by the pulley whilst spinning,
gave the total force in pounds, applied to the respective mules whilst
spinning; for instance, suppose a mule to be driven by a pulley 12
inches diameter (3·14 ft. in circumference), such pulley making 58
revolutions during the spinning as above, and that it required a force
equal to 30 lbs. weight to maintain the motion of the mule, then 30 lbs.
× 3·14 feet circumference of pulley × 58 revolutions in spinning = 5463
lbs. of force employed during the spinning, to the period of backing
off.

Mr. James Smith, of Deanstone cotton works in Scotland, obtained a
patent for the invention of a _self-actor_, in February, 1834. He does
not perform the backing-off by reversing the rotation of the spindle, as
in common mules, or as in Mr. Roberts’, but by elevating the
counterfaller wire, which, being below the ends of the yarn or thread,
along the whole extent of the carriage, thereby pulls off or strips the
spiral coils at the point of the spindle, instead of unwinding them, as
of old. This movement he considers to be of great importance towards
simplifying the machinery for rendering the mule self-acting; and the
particular way in which he brings the stripper into action is no doubt
ingenious, but it has been supposed by many to strain the yarn. He
claims as his invention the application and adaptation of a mangle wheel
or mangle rack to the mule, for effecting certain successive movements,
either separately or in conjunction; he claims that arrangement of the
carriages of a pair of mules, by which the stretch is caused to take
place over part of the same ground by both carriages, and thereby the
space required for the working of a pair of mules is greatly diminished;
and he claims the application of a weight, spring, or friction, for
balancing the tension of the ends of the threads.

A patent was granted, in April, 1835, to Mr. Joseph Whitworth, engineer
in Manchester, for some ingenious modifications of the mechanism of the
mule, subservient to automatic purposes. His machinery is designed,
first, to traverse the carriage in and out, by means of screws or
worm-shafts, which are placed so as to keep the carriage parallel to the
drawing rollers, and prevent the necessity of squaring bands, hitherto
universally employed; secondly, his invention consists in an improved
manner of working the drums of a self-acting mule by geer; thirdly, in
the means of effecting the backing off; fourthly, in the mechanism for
working the faller-wire in building the cops; and fifthly, in the
apparatus for effecting the winding of the yarns upon the spindles. As
regards the throstles and doubling frames, his improvements apply,
first, to the peculiar method of constructing and adapting the flyers
and spindles, and producing the drag; and, secondly, to the arrangement
of the other parts of the doubling machinery.

See LACE-MAKING, SINGEING, TEXTILE FABRIC, THREAD MANUFACTURE, and
WEAVING.

The Imports of Cotton Wool for home consumption into the United Kingdom
were in the year ending 5th January,

  +-------------------------------------------+-----------+-----------+
  |                                           |   1836.   |   1837.   |
  |                                           +-----------+-----------+
  |                                           |    lbs.   |    lbs.   |
  |From the British possessions in America    |  1,346,220|  1,041,434|
  |   --      do.        do.       East Indies| 43,404,058| 34,060,055|
  |   --    United States of America          |287,346,721|309,027,306|
  |   --    Brazil                            | 26,879,779| 20,822,509|
  |   --    Egypt                             |  5,184,743|  7,465,774|
  |Otherwise imported                         |  6,789,603|  5,602,602|
  |                                           +-----------+-----------+
  |                          Total            |370,951,124|378,019,680|
  +-------------------------------------------+-----------+-----------+
  |                                                 _£_         _£_   |
  |The Exports of Cotton Manufactures           18,511,692  13,625,464|
  |         --           Yarn                    6,120,366   6,953,467|
  +-------------------------------------------------------------------+


COURT PLASTER, is a considerable object of manufacture. It is made as
follows:

Black silk is strained and brushed over ten or twelve times with the
following preparation:--Dissolve 1/2 an ounce of balsam of benzoin in 6
ounces of rectified spirits of wine; and in a separate vessel dissolve 1
ounce of isinglass in as little water as may be. Strain each solution,
mix them, and let the mixture rest, so that any undissolved parts may
subside; when the clear liquid is cold it will form a jelly, which must
be warmed before it is applied to the silk. When the silk coated with it
is quite dry, it must be finished off with a coat of a solution of 4
ounces of China turpentine in 6 ounces of tincture of benzoin, to
prevent its cracking.[22]

  [22] Paris’s Pharmacologia.


CRAPE. (_Crêpe_, Fr.; _Krepp_, Germ.) A transparent textile fabric,
somewhat like gauze, made of raw silk, gummed and twisted at the mill.
It is woven with any crossing or tweel. When dyed black, it is much worn
by ladies as a mourning dress. Crapes are crisped (_crepés_) or smooth;
the former being double, are used in close mourning, the latter in less
deep. White crape is appropriate to young unmarried females, and to
virgins on taking the veil in nunneries. The silk destined for the first
is spun harder than for the second; since the degree of twist,
particularly of the warp, determines the degree of crisping which it
assumes after being taken from the loom. It is for this purpose steeped
in clear water, and rubbed with prepared wax. Crapes are all woven and
dyed with the silk in the raw state. They are finished with a stiffening
of gum water.

Crape is a Bolognese invention, but has been long manufactured with
superior excellence at Lyons in France, and Norwich in England. There is
now a magnificent fabric of it at Yarmouth, by power-loom machinery.

There is another kind of stuff, called _crepon_, made either of fine
wool, or of wool and silk, of which the warp is twisted much harder than
the weft. The _crepons_ of Naples consist altogether of silk.


CRAYONS. (Eng. and Fr.; _Pastelstifte_, Germ.) Slender, soft, and
somewhat friable cylinders, variously coloured for delineating figures
upon paper, usually called chalk drawings. Red, green, brown, and other
coloured crayons, are made with fine pipe or china clay paste,
intimately mixed with earthy or metallic pigments, or in general with
body or surface colours, then moulded and dried. The brothers Joel, in
Paris, employ as crayon cement the following composition: 6 parts of
shell-lac, 4 parts of spirit of wine, 2 parts of turpentine, 12 parts of
a colouring powder, such as Prussian-blue, orpiment, whitelead,
vermillion, &c., and 12 parts of blue clay. The clay being elutriated,
passed through a hair sieve, and dried, is to be well incorporated by
trituration with the solution of the shell-lac in the spirit of wine,
the turpentine, and the pigment; and the doughy mass is to be pressed in
proper moulds, so as to acquire the desired shape. They are then dried
by a stove heat.

In order to make cylindrical crayons, a copper cylinder is employed,
about 2 inches in diameter, and 1-1/2 inches long, open at one end, and
closed at the other with a perforated plate, containing holes
corresponding to the sizes of the crayons. The paste is introduced into
the open end, and forced through the holes of the bottom by a piston
moved by a strong press. The vermicular pieces that pass through are cut
to the proper lengths, and dried. As the quality of the crayons depends
entirely upon the fineness of the paste, mechanical means must be
resorted to for effecting this object in the best manner. The following
machine has been found to answer the purpose exceedingly well.

[Illustration: 350 351]

_Fig._ 350. is a vertical section through the centre of the crayon mill.
_Fig._ 351. is a view of the mill from above. A, the mill tub, whose
bottom B must be a hard flat plate of cast iron; the sides A being of
wood or iron at pleasure. In the centre of the bottom there is a pivot
C, screwed into a socket cast upon the bottom, and which may be
strengthened by two cross bars D, made fast to the frame E. F, the
millstone of cast-iron, concave, whose diameter is considerably smaller
than that of the vessel A; it is furnished within with a circular basin
of wood G, which receives the materials to be ground, and directs them
to the holes H, which allow them to pass down between the under part of
the muller, and the bottom of the tub, to undergo trituration.

By the centrifugal motion, the paste is driven towards the sides of the
vessel, rises over the sides of the muller, and comes again through the
holes H, so as to be repeatedly subjected to the grinding operation.
This millstone is mounted upon an upright shaft I, which receives
rotatory motion from the bevel wheel work K, driven by the winch L.

[Illustration: 352 353]

The furnace in which some kinds of crayons, and especially the
factitious blacklead pencils are baked, is represented in _fig._ 352. in
a front elevation; and in _fig._ 353., which is a vertical section
through the middle of the chimney.

A A, six tubes of greater or less size, according as the substance of
the crayons is a better or worse conductor of heat. These tubes, into
which the crayons intended for baking are to be put, traverse
horizontally the laboratory B of the furnace, and are supported by two
plates C, pierced with six square holes for covering the axes of the
tubes A. These two plates are hung upon a common axis D; one of them,
with a ledge, shuts the cylindrical part of the furnace, as is shown in
the figure. At the extremity of the bottom, the axis D is supported by
an iron fork fixed in the brickwork; at the front it crosses the plate
C, and lets through an end about 4 inches square to receive a key, by
means of which the axis D may be turned round at pleasure, and thereby
the two plates C, and the six tubes A, are thus exposed in succession to
the action of the fire in an equal manner upon each of their sides. At
the two extremities of the furnace are two chimnies E, for the purpose
of diffusing the heat more equably over the body of the crayons. F,
_fig._ 352., is the door of the fire-place, by which the fuel is
introduced; G, _fig._ 353., the ash-pit; H, the fire-place; I, holes of
the grate which separate the fire-place from the ash-pit; K, brickwork
exterior to the furnace.

General Lomet proposes the following composition for red crayons. He
takes the softest hematite, grinds it upon a porphyry slab; and then
carefully elutriates it. He makes it into a plastic paste with gum
arabic and a little white soap, which he forms by moulding, as above,
through a syringe, and drying, into crayons. The proportions of the
ingredients require to be carefully studied.


CRAYONS, _lithographic_. Various formulæ have been given for the
formation of these crayons. One of these prescribes, white wax, 4 parts;
hard tallow-soap, shell-lac, of each 2 parts; lamp black, 1 part.
Another is, dried tallow soap and white wax, each 6 parts; lamp black, 1
part. This mixture being fused with a gentle heat, is to be cast into
moulds for forming crayons of a proper size.


CREOSOTE, or the _flesh-preserver_, from κρεας and σωζω, is the most
important of the five new chemical products obtained from wood tar by
Dr. Reichenbach. The other four, _paraffine_, _eupione_, _picamar_, and
_pittacal_, have hitherto been applied to no use in the arts, and may be
regarded at present as mere analytical curiosities.

Creosote may be prepared either from tar or from crude pyrolignous acid.
The tar must be distilled till it acquires the consistence of pitch, and
at the utmost till it begins to exhale the white vapours of paraffine.
The liquor which passes into the receiver divides itself into 3 strata,
a watery one in the middle, placed between a heavy and a light oil. The
lower stratum alone is adapted to the preparation of creosote.

1. The liquor being saturated with carbonate of potash, is to be allowed
to settle, and the oily matter which floats at top is to be decanted
off. When this oil is distilled, it affords at first, products lighter
than water, which are to be rejected, but the heavier oil which follows
is to be separated, washed repeatedly by agitation, with fresh portions
of dilute phosphoric acid, to free it from ammonia, then left some time
at rest, after which it must be washed by water from all traces of
acidity, and finally distilled along with a new portion of dilute
phosphoric acid, taking care to _cohobate_, or pour back the distilled
product repeatedly into the retort.

2. The oily liquid thus rectified is colourless; it contains much
_creosote_, but at the same time some _eupione_, &c. It must therefore
be mixed with potash lye at 1·12 sp. grav., which dissolves the
creosote. The eupione floats upon the surface of that solution, and may
be decanted off. The alkaline solution is to be exposed to the air, till
it blackens by decomposition of some foreign matter. The potash being
then saturated with dilute sulphuric acid, the creosote becomes free,
when it may be decanted or syphoned off and distilled.

3. The treatment by potash, sulphuric acid, &c., is to be repeated upon
the brownish creosote till it remains colourless, or nearly so, even
upon exposure to air. It must be now dissolved in the strongest potash
lye, subjected to distillation anew, and lastly, re-distilled with the
rejection of the first products which contain much water, retaining only
the following, but taking care not to push the process too far.

In operating upon pyrolignous acid, if we dissolve effloresced sulphate
of soda in it to saturation, at the temperature of 167° F., the creosote
oil will separate, and float upon the surface. It is to be decanted,
left in repose for some days, during which it will part with a fresh
portion of the vinegar and salt. Being now saturated while hot, with
carbonate of potash and distilled with water, an oily liquor is
obtained, of a pale yellow colour. This is to be rectified by phosphoric
acid, &c., like the crude product of creosote from tar.

Creosote is apparently composed of 76·2 carbon, 7·8 hydrogen, and 16·0
oxygen, in 100 parts. It is an oily looking liquid, slightly greasy to
the touch, void of colour, having an acrid burning taste, and capable of
corroding the epidermis in a short time. It possesses a penetrating
disagreeable smell, like that of highly smoked hams, and when inhaled up
the nostrils, causes a flow of tears. Its specific gravity is 1·037, at
58° F. Its consistence is similar to that of oil of almonds. It has no
action upon the colours of litmus or turmeric, but communicates to white
paper a stain which disappears spontaneously in a few hours, and rapidly
by the application of heat.

It boils without decomposition at 398° F., under the average barometric
pressure, remains fluid at 16° F., is a non-conductor of electricity,
refracts light powerfully, and burns in a lamp with a ruddy smoky flame.

When mixed with water at 58° F. it forms two different combinations, the
first being a solution of 1 part of creosote in 400 of water; the
second, a combination of 1 part of water with 10 parts of creosote. It
unites in all proportions with alcohol, hydric ether, acetic ether,
naphtha, eupione, carburet of sulphur, &c.

Creosote dissolves a large quantity of iodine and phosphorus, as also of
sulphur with the aid of heat, but it deposits the greater part of them
in crystals, on cooling. It combines with potash, soda, ammonia, lime,
baryta, and oxide of copper. Oxide of mercury converts creosote into a
resinous matter, while itself is reduced to the metallic state. Strong
sulphuric and nitric acids decompose it.

Creosote dissolves several salts, particularly the acetates, and the
chlorides of calcium and tin; it reduces the nitrate and acetate of
silver. It also dissolves indigo blue; a remarkable circumstance. Its
action upon animal matters is very interesting. It coagulates albumen,
and prevents the putrefaction of butcher’s meat and fish. For this
purpose these substances must be steeped a quarter of an hour in a weak
watery solution of creosote, then drained and hung up in the air to dry.
Hence Reichenbach has inferred that it is owing to the presence of
creosote, that meat is cured by smoking; but he is not correct in
ascribing the effect to the mere coagulation of the albumen, since
_fibrine_ alone, without creosote, will putrefy in the course of 24
hours, during the heats of summer. It kills plants and small animals. It
preserves flour paste unchanged for a long time.

_Creosote_ exists in the tar of beech-wood, to the amount of from 20 to
25 per cent., and in crude pyrolignous acid, to that of 1-1/2.

It ought to be kept in well-stoppered bottles, because when left open,
it becomes progressively yellow, brown, and thick.

Creosote has considerable power upon the nervous system, and has been
applied to the teeth with advantage in odontalgia, as well as to the
skin in recent scalds. But its medicinal and surgical virtues have been
much exaggerated. Its flesh-preserving quality is rendered of little
use, from the difficulty of removing the rank flavour which it imparts.


CRUCIBLES; (_Creusets_, Fr.; _Schmelztiegel_, Germ.) are small conical
vessels, narrower at the bottom than the mouth, for reducing ores in
docimasy by the dry analysis, for fusing mixtures of earthy and other
substances, for melting metals, and compounding metallic alloys. They
ought to be refractory in the strongest heats, not readily acted upon by
the substances ignited in them, not porous to liquids, and capable of
bearing considerable alternations of temperature without cracking; on
which account they should not be made too thick. The best crucibles are
formed from a pure fire clay, mixed with finely ground _cement_ of old
crucibles, and a portion of black-lead or graphite. Some pounded coak
may be mixed, with the plumbago. The clay should be prepared in a
similar way as for making pottery ware; the vessels after being formed
must be slowly dried, and then properly baked in the kiln. Crucibles
formed of a mixture of 8 parts in bulk of Stourbridge clay and cement, 5
of coak, and 4 of graphite, have been found to stand 23 meltings of 76
pounds of iron each, in the Royal Berlin foundry. Such crucibles
resisted the greatest possible heat that could be produced, in which
even wrought iron was melted, equal to 150° or 155° Wedgewood; and bore
sudden cooling without cracking. Another composition for brass-founding
crucibles is the following:--1/2 Stourbridge clay; 1/4 burned clay
cement; 1/8 coak powder; 1/8 pipe clay. The pasty mass must be
compressed in moulds. The Hessian crucibles from Great Almerode and
Epterode are made from a fire clay which contains a little iron, but no
lime; it is incorporated with siliceous sand. The dough is compressed in
a mould, dried, and strongly kilned. They stand saline and leaden fluxes
in docimastic operations very well; are rather porous on account of the
coarseness of the sand, but are thereby less apt to crack from sudden
heating or cooling. They melt under the fusing point of bar iron.
Beaufay in Paris has lately succeeded in making a tolerable imitation of
the Hessian crucibles with a fire clay found near Namur in the Ardennes.

Berthier has published the following elaborate analyses of several kinds
of crucibles:--

  +--------+------+------+-------+--------+--------+---------+--------+
  |        | Hes- | Beau-|English| St. E- | Glass  |Bohemian | Glass  |
  |        | sian.| fay. |       | tienne |Pots at |  Glass  |Pots, of|
  |        |      |      | for Cast Steel.|Nemours.|  Pots.  |Creusot.|
  +--------+------+------+-------+--------+--------+---------+--------+
  |Silica  |70·9  |64·6  |  63·7 |  65·2  |  67·4  |  68·0   |  68·0  |
  |Alumina |24·8  |34·4  |  20·7 |  25·0  |  32·0  |  29·0   |  28·0  |
  |Oxide of|      |      |       |        |        |         |        |
  |Iron    | 3·8  | 1·0  |   4·0 |   7·2  |   0·8  |   2·2   |  2·0   |
  |Magnesia| trace| --   |   --  |  trace |  trace |   0·5   | trace  |
  |Water   |  --  | --   |  10·3 |   --   |   --   |   --    |  1·0   |
  |        |      |      |  [23] |        |        |         |        |
  +--------+------+------+-------+--------+--------+---------+--------+

  [23] This crucible had been analyzed before being baked in the kiln.

Wurzer states the composition of the sand and clay in the Hessian
crucibles as follows:--

  _Clay;_ silica 10·1; alumina 65·4; oxides of iron    lime 0·3; water 23
                                     and manganese 1·2;
  _Sand;_        95·6           2·1                1·5      0·8

_Black lead_ crucibles are made of two parts of graphite and one of fire
clay; mixed with water into a paste, pressed in moulds, and well dried;
but not baked hard in the kiln. They bear a higher heat than the Hessian
crucibles, as well as sudden changes of temperature; have a smooth
surface, and are therefore preferred by the melters of gold and silver.
This compound forms excellent small or portable furnaces.

Mr. Anstey describes his patent process for making crucibles, as
follows: Take two parts of fine ground raw Stourbridge clay, and one
part of the hardest gas coak, previously pulverized, and sifted through
a sieve of one-eighth of an inch mesh (if the coak is ground too fine,
the pots are very apt to crack). Mix the ingredients together with the
proper quantity of water, and tread the mass well. The pot is moulded by
hand upon a wooden block, supported on a spindle which turns in a hole
in the bench; there is a gauge to regulate the thickness of the melting
pot, and a cap of linen or cotton placed wet upon the core before the
clay is applied, to prevent the clay from sticking partially to the
core, in the taking off; the cap adheres to the pot only while wet, and
may be removed without trouble or hazard when dry. He employs a wooden
bat to assist in moulding the pot; when moulded it is carefully dried at
a gentle heat. A pot dried as above, when wanted for use, is first
warmed by the fire-side, and is then laid in the furnace with the mouth
downwards (the red coaks being previously damped with cold ones in order
to lessen the heat); more coak is then thrown in till the pot is
covered, and it is now brought up gradually to a red heat. The pot is
next turned and fixed in a proper position in the furnace, without being
allowed to cool, and is then charged with cold iron, so that the metal,
when melted, shall have its surface a little below the mouth of the pot.
The iron is melted in about an hour and a half, and no flux or addition
of any kind is made use of. A pot will last for fourteen or even
eighteen successive meltings, provided it is not allowed to cool in the
intervals; but if it cool, it will probably crack. These pots it is said
can bear a greater heat than others without softening, and will,
consequently, deliver the metal in a more fluid state than the best
Birmingham pots will. See a figure of the crucible mould under STEEL.


CRYSTAL, is the geometrical form possessed by a vast number of mineral
and saline substances; as also by many vegetable and animal products.
The integrant particles of matter have undoubtedly determinate forms,
and combine with one another, by the attraction of cohesion, according
to certain laws, and points of polarity, whereby they assume a vast
variety of secondary crystalline forms. The investigation of these laws
belongs to crystallography, and is foreign to the practical purpose of
this volume. Instructions are given under each object of manufacture
which requires crystallization, how to conduct this process; see BORAX,
SALT, &c.


CUDBEAR was first made an article of trade in this country, by Dr.
Cuthbert Gordon, from whom it derived its name, and was originally
manufactured on a great scale by Mr. G. Mackintosh at Glasgow, nearly 60
years ago. Cudbear or persio is a powder of a violet red colour,
difficult to moisten with water, and of a peculiar but not disagreeable
odour. It is partially soluble in boiling water, becomes red with acids,
and violet blue with alkalis. It is prepared in the same way as archil,
only toward the end the substance is dried in the air, and is then
ground to a fine powder, taking care to avoid decomposition, which
renders it glutinous. In Scotland they use the lichen tartareus, more
rarely the lichen calcareus, and omphalodes; most of which lichens are
imported from Sweden and Norway, under the name of rock moss. The lichen
is suffered to ferment for a month, and is then stirred about to allow
any stones which may be present to fall to the bottom. The red mass is
next poured into a flat vessel, and left to evaporate till its urinous
smell has disappeared, and till it has assumed an agreeable colour
verging upon violet. It is then ground to fine powder. During the
fermentation of the lichen, it is watered with stale urine, or with an
equivalent ammoniacal liquor of any kind, as in making archil.


CUPELLATION; is a mode of analyzing gold, silver, palladium, and
platinum, by adding to small portions of alloys, containing these
metals, a bit of lead, fusing the mixture in a little _cup_ of bone
earth called a _cupel_, then by the joint action of heat and air,
oxidizing the copper, tin, &c., present in the precious metals. The
oxides thus produced, are dissolved and carried down into the porous
_cupel_ in a liquid state, by the vitrified oxide of lead. See ASSAY,
GOLD, and SILVER.


CURRYING OF LEATHER, (_Corroyer_, Fr.; _Zurichten_, Germ.) is the art of
dressing skins after they are tanned, for the purposes of the
shoe-maker, coach and harness maker, &c., or of giving them the
necessary smoothness, lustre, colour, and suppleness. The currier’s shop
has no resemblance to the tanner’s premises, having a quite different
set of tools and manipulations.

The currier employs a strong hurdle about a yard square, made either of
basket twigs, or of wooden spars, fixed rectangularly like trellis work,
with holes 3 inches square, upon which he treads the leather, or beats
it with a mallet or hammer, in order to soften it, and render it
flexible.

The _head knife_, called in French _couteau a revers_, on account of the
form of its edge, which is much turned over, is a tool 5 or 6 inches
broad, and 15 or 16 long; with two handles, one in the direction of the
blade, and the other perpendicular to it, for the purpose of guiding the
edge more truly upon the skin. The pommel (_paumelle_) is so called
because it clothes the palm of the hand, and performs its functions. It
is made of hard wood, and of a rectangular shape, 1 foot long, 5 inches
broad, flat above and rounded below. It is furrowed over the rounded
surface with transverse parallel straight grooves. These grooves are in
section sharp-edged isosceles triangles. _Fig._ 354. and 355., represent
the pommel in an upper and under view. The flat surface is provided with
a leather strap for securing it to the hand of the workman. Pommels are
made of different sizes, and with grooves of various degrees of
fineness. Cork pommels are also used, but they are not grooved. Pommels
serve to give grain and pliancy to the skins.

[Illustration: 354 355 356]

The _stretching iron_, _fig._ 356., is a flat plate of iron or copper,
fully a fourth of an inch thick at top, and thinning off at bottom in a
blunt edge, shaped like the arc of a circle of large diameter, having
the angles _a_ and _b_ rounded, lest in working they should penetrate
the leather. The top _c_ is mounted with leather to prevent it from
hurting the hands. A copper stretching knife is used for delicate skins.
The workman holds this tool nearly perpendicular, and scrapes the thick
places powerfully with his two hands, especially those where some tan or
flesh remains. He thus equalizes the thickness of the skin, and renders
it at the same time more dense and uniform in texture. This tool is of
very general use in currying.

[Illustration: 357 358]

The round knife, _fig._ 357. and 358. (_lunette_ in French), is a
circular knife from 10 to 12 inches in diameter, with a round 4 or 5
inch hole in its centre, for introducing the hands and working it. It is
concave, as shown in the section _fig._ 358., presenting the form of a
spherical zone. The concave part is that applied to the skin. Its edge
is not perfectly straight; but is a little turned over on the side
opposite to the skin, to prevent it from entering too far into the
leather. The currier first slopes off with the head knife from the
edges, a portion equal to what he afterwards removes with the round one.
By this division the work is done sooner and more exactly. All the oiled
or greased skins are dressed with the round knife.

[Illustration: 359]

The _cleaner_ is a straight two-handled knife two inches broad, of which
there are two kinds, a sharp-edged and a blunt one. _Fig._ 359.

The _mace_ is made of wood, having a handle 30 inches long, with a
cubical head or mallet; upon the two faces of which, parallel to the
line of the handle, there are 4 pegs of hard wood turned of an
egg-shape, and well polished, so as not to tear the moistened leather
when it is strongly beat and softened with the mace.

[Illustration: 360]

The horse or trestle, _fig._ 360., consists of a strong wooden frame, A
B C D, which serves as a leg or foot. Upon the middle of this frame
there are two uprights, E F, and a strong cross beam, G, for supporting
the thick plank H, upon which the skins are worked. This plank may be
set at a greater or less slope, according as its lower end is engaged in
one or other of the cross bars, I I I I, of the frame. In the figure, a
skin K is represented upon the plank with the head knife upon it, in the
act of being pared.

A cylindrical bar fixed horizontally at its ends to two buttresses
projecting from the wall, serves by means of a parallel stretched cord,
to fix a skin by a coil or two in order to dress it. This is accordingly
called the _dresser_. The tallow cloth is merely a mop made of stout
rags, without the long handle; of which there are several, one for wax,
another for oil, &c. Strong-toothed pincers with hook-end handles, drawn
together by an endless cord, are employed to stretch the leather in any
direction, while it is being dressed. The currier uses clamps like the
letter U, to fix the edges of the leather to his table. His polisher is
a round piece of hard wood, slightly convex below, with a handle
standing upright in its upper surface, for seizing it firmly. He first
rubs with sour beer, and finishes with barberry juice.

Every kind of tanned leather not intended for soles or such coarse
purposes, is generally curried before being delivered to the workmen who
fashion it, such as shoemakers, coachmakers, saddlers, &c. The chief
operations of the currier are four:--

1. Dipping the leather, which consists in moistening it with water, and
beating it with the _mace_, or a mallet upon the hurdle. He next applies
the _cleaners_, both blunt and sharp, as well as the head knife, to
remove or thin down all inequalities. After the leather is shaved, it is
thrown once more into water, and well scoured by rubbing the grain side
with pumice stone, or a piece of slaty grit, whereby it parts with the
bloom, a whitish matter, derived from the oak bark in the tan pit.

2. Applying the pommel to give the leather a granular appearance, and
correspondent flexibility. The leather is first folded with its grain
side in contact, and rubbed strongly with the pommel, then rubbed simply
upon its grain side; whereby it becomes extremely flexible.

3. Scraping the leather. This makes it of uniform thickness. The workman
holds the tool nearly perpendicular upon the leather, and forcibly
scrapes the thick places with both his hands.

4. Dressing it by the round knife. For this purpose he stretches the
leather upon the wooden cylinder, lays hold of the pendent under edge
with the pincers attached to his girdle, and then with both hands
applies the edge of the knife to the surface of the leather, slantingly
from above downwards, and thus pares off the coarser fleshy parts of the
skin. This operation requires great experience and dexterity; and when
well performed improves greatly the look of the leather.

The hide or skin being rendered flexible and uniform, is conveyed to the
shed or drying house, where the greasy substances are applied, which is
called dubbing (daubing), or stuffing. The oil used for this purpose is
prepared by boiling sheep-skins or doe-skins, in cod oil. This
application of grease is often made before the graining board or pommel
is employed.

Before waxing, the leather is commonly coloured by rubbing it with a
brush dipped into a composition of oil and lamp black on the flesh side,
till it be thoroughly black; it is then black-sized with a brush or
sponge, dried, tallowed with the proper cloth, and slicked upon the
flesh with a broad smooth lump of glass; sized again with a sponge; and
when dry, again curried as above described.

Currying leather on the hair or grain side, termed black on the grain,
is the same in the first operation with that drest on the flesh, till it
is scoured. Then the first black is applied to it while wet, by a
solution of copperas put upon the grain, after this has been rubbed with
a stone; a brush dipped in stale urine is next rubbed on, then an iron
slicker is used to make the grain come out as fine as possible. It is
now stuffed with oil. When dry, it is seasoned; that is, rubbed over
with a brush dipped in copperas water, on the grain, till it be
perfectly black. It is next slicked with a good grit-stone, to take out
the wrinkles, and smooth the coarse grain. The grain is finally raised
with the pommel or graining board, by applying it to the leather in
different directions. When thoroughly dry, it is grained again in two or
three ways.

Hides intended for covering coaches are shaved nearly as thin as shoe
hides, and blacked upon the grain.


CUTLERY. (_Coutellerie_, Fr.; _Messerschmidwaare_, Germ.) Three kinds of
steel are made use of in the manufacture of different articles of
cutlery, viz. common steel, shear steel, and cast steel. Shear steel is
exceedingly plastic and tough. All the edge tools which require great
tenacity without great hardness are made of it, such as table knives,
scythes, plane-irons, &c.

Cast steel is formed by melting blistered steel in covered crucibles,
with bottle glass, and pouring it into cast-iron moulds, so as to form
it into ingots: these ingots are then taken to the tilt, and drawn into
rods of suitable dimensions. No other than cast steel can assume a very
fine polish, and hence all the finer articles of cutlery are made of it,
such as the best scissors, penknives, razors, &c.

Formerly cast steel could be worked only at a very low heat; it can now
be made so as to be welded to iron with the greatest ease. Its use is
consequently extended to making very superior kinds of chisels,
plane-irons, &c.

_Forging of table knives._--Two men are generally employed in the
forging of table knives; one called the foreman or maker, and the other
the striker.

The steel called common steel is employed in making the very common
articles; but for the greatest part of table knives which require a
surface free from flaws, shear steel is generally preferred. That part
of the knife termed the blade, is first rudely formed and cut off. It is
next welded to a rod of iron about 1/2 inch square, in such a manner as
to leave as little of the iron part of the blade exposed as possible. A
sufficient quantity of the iron now attached to the blade, is taken off
from the rod to form the bolster or shoulder, and the tang.

In order to make the bolster of a given size, and to give it at the same
time shape and neatness, it is introduced into a die, and a swage placed
upon it; the swage has a few smart blows given it by the striker. This
die and swage are, by the workman, called prints.

After the tangs and bolster are finished, the blade is heated a second
time, and the foreman gives it its proper anvil finish; this operation
is termed smithing. The blade is now heated red-hot, and plunged
perpendicularly into cold water. By this means it becomes hardened. It
requires to be tempered regularly down to a blue colour: in which state
it is ready for the grinder.

Mr. Brownill’s method of securing the handles upon table-knives and
forks, is, by lengthening the tangs, so as to pass them completely
through the handle, the ends of which are to be tinned after the
ordinary mode of tinning iron; and, when passed through the handle, the
end of the tang is to be spread by beating, or a small hole drilled
through it, and a pin passed to hold it upon the handle. After this,
caps of metal, either copper plated, or silver, are to be soldered on to
the projecting end of the tang, and while the solder is in a fluid
state, the cap is to be pressed upon the end of the handle and held
there until the solder is fixed, when the whole is to be cooled by being
immersed in cold water.

Mr. Thomason’s patent improvements consist in the adaptation of steel
edges to the blades of gold and silver knives. These steel edges are to
be attached to the other metal of whatever quality it may be, of which
the knife, &c. is made, by means of solder, in the ordinary mode of
effecting that process. After the edge of steel is thus attached to the
gold, silver, &c., it is to be ground, polished, and tempered by
immersion in cold water, or oil, after being heated. This process being
finished, the other parts of the knife are then wrought and ornamented
by the engraver or chaser, as usual.

A patent was obtained in 1827, by Mr. Smith of Sheffield, for rolling
out knives at one operation.

In the ordinary mode of making knives, a sheet of steel being provided,
the blades are cut out of the sheet, and the backs, shoulders, and
tangs, of wrought iron, are attached to the steel blades, by welding at
the forge. The knife is then ground to the proper shape, and the blade
polished and hardened.

Instead of this welding process, the patentee proposes to make the
knives entirely of steel, and to form them by rolling in a heated state
between massive rollers; the shoulders or bolsters, and the tangs for
the handles being produced by suitable recesses in the peripheries of
the rollers; just as rail-way rails are formed. When the knife is to be
made with what is called a scale tang, that is a broad flat tang, to
which the handle is to be attached in two pieces, riveted on the sides
of the tang, the rollers are then only to have recesses cut in them, in
a direction parallel to the axis for forming the bolster.

The plate of steel having been heated, is to be pressed between the two
rollers, by which the blades and the parts for the scale tangs will be
pressed out flat and thin, and those parts which pass between the
grooves or recess will be left thick or protuberant, forming the bolster
for the shoulder of the blade. But if the tangs are to be round in order
to be fixed into single handles, then it will be necessary also to form
transverse grooves in the rollers, that is, at right angles to those
which give shape to the bolsters, the transverse grooves corresponding
in length to the length of the intended tang. When the plates of steel
have been thus rolled, forming three or more knives in a breadth, the
several knives are to be cut out by the ordinary mode of what is called
slitting, and the blades and shoulders ground, hardened, and polished in
the usual way.

Forks are generally a distinct branch of manufacture from that of
knives, and are purchased of the fork makers by the manufacturers of
table knives, in a state fit for receiving the handles.

The rods of steel from which the forks are made, are about 3/8ths of an
inch square. The tang and shank of the fork are first roughly formed.
The fork is then cut off, leaving at one end about 1 inch of the square
part of the steel. This part is afterwards drawn out flat to about the
length of the prongs. The shank and tang are now heated, and a proper
form given to them by means of a die and swage. The prongs are
afterwards formed at one blow by means of the stamp; this machine is
very similar to that used in driving piles, but it is worked by one man.
It consists of a large anvil fixed in a block of stone nearly on a level
with the ground. To this anvil are attached two rods of iron of
considerable thickness, fixed 12 inches asunder, perpendicularly to the
anvil, and diagonally to each other. These are fastened to the ceiling.
The hammer or stamp, about 100 lbs. in weight, having a groove upon
either side corresponding to the angles of the upright rods, is made to
slide freely through its limited range, being conducted by its two iron
supporters. A rope is attached to the hammer, which goes over a pulley
on the floor of the room above, and comes down to the person who works
the stamp: two corresponding dies are attached, one to the hammer, and
the other to the anvil. That part of the fork intended to form the
prongs, is heated to a pretty white heat and placed in the lower die,
and the hammer containing the other die is made to fall upon it from a
height of about 7 or 8 feet. This forms the prongs and the middle part
of the fork, leaving a very thin substance of steel between each prong,
which is afterwards cut out with an appropriate instrument called a
flie-press. The forks are now annealed by surrounding a large mass of
them with hot coals, so that the whole shall become red hot. The fire is
suffered gradually to die out, and the forks to cool without being
disturbed. This process is intended to soften, and by that means to
prepare them for filing. The inside of the prongs are then filed, after
which they are bent into their proper form and hardened. When hardened,
which is effected by heating them red-hot and plunging them into cold
water, they are tempered by exposing them to the degree of heat at which
grease inflames. See STAMPS.

Penknives are generally forged by a single hand, with the hammer and the
anvil simply. The hammer in this trade is generally light, not exceeding
3-1/2 lbs. The breadth of the face, or the striking part, is about one
inch; if broader, it would not be convenient for striking so small an
object. The principal anvil is about 5 inches, and 10 upon the face, and
is provided with a groove into which a smaller anvil is wedged. The
smaller anvil is about 2 inches square upon the face. The blade of the
knife is first drawn out at the end of the rod of steel, and as much
more is cut off along with it as is thought necessary to form the joint.
The blade is then taken in a pair of tongs, and heated a second time to
finish the joint part, and at the same time to form a temporary tang for
the purpose of driving into a small haft used by the grinder. Another
heat is taken to give the blade a proper finish. The small recess called
the nail hole, used in opening the knife, is made while it is still hot
by means of a chisel, which is round on one side, and flat upon the
other.

Penknives are hardened by heating the blade red hot, and dipping them
into water up to the shoulder. They are tempered by setting them side by
side, with the back downwards upon a flat iron plate laid upon the fire,
where they are allowed to remain till they are of a brown or purple
colour.

The blades of pocket knives, and all that come under the denomination of
spring knives, are made in the same way.

The forging of razors is performed by a foreman and striker, as in
making table knives.

They are generally made of cast steel. The rods, as they come from the
tilt, are about 1/2 inch broad, and of a thickness sufficient for the
back of the razor.

There is nothing peculiar in the tools made use of in forging razors:
the anvil is a little rounded at the sides, which affords the
opportunity of making the edge thinner, and saves an immense labour to
the grinder.

Razors are hardened and tempered in a similar manner to penknives. They
are, however, left harder, being only let down to yellow or brown
colour.

The forging of scissors is wholly performed by the hammer, and all the
sizes are made by a single hand. The anvil of the scissor-maker weighs
about 1-1/2 cwt.; it measures, on the face, about 4 by 11 inches. It is
provided with two gates or grooves for the reception of various little
indented tools termed by the workman bosses; one of these bosses is
employed to give proper figure to the shank of the scissors; another for
forming that part which has to make the joint; and a third is made use
of for giving a proper figure to the upper side of the blade. There is
also another anvil placed on the same block, containing two or three
tools called beak-irons, each consisting of an upright stem about 6
inches high, at the top of which a horizontal beak projects; one of
these beaks is conical, and is used for extending the bow of the
scissors; the other is a segment of a cylinder with the round side
upwards, containing a recess for giving a proper shape and smoothness to
the inside of the bow.

The shank of the scissors is first formed by means of one of the bosses,
above described, leaving as much steel at the end as will form the
blade. A hole is then punched about 1/4 inch in width, a little above
the shank. The blade is drawn out and finished, and the scissors
separated from the rod a little above the hole. It is heated a third
time, and the small hole above mentioned is extended upon the beak-irons
so as to form the bow. This finishes the forging of scissors. They are
promiscuously made in this way, without any other guide than the eye,
having no regard to their being in pairs. They are next annealed for the
purpose of filing such parts of them as cannot be ground, and afterwards
paired.

The very large scissors are made partly of iron, the blades being of
steel.

After the forging, the bow and joints, and such shanks as cannot be
ground, are filed. The rivet hole is then bored, through which they are
to be screwed or riveted together. This common kind of scissors is only
hardened up to the joint. They are tempered down to a purple or blue
colour. In this state they are taken to the grinder.

_Grinding and polishing of cutlery._--The various processes which come
under this denomination are performed by machinery, moving in general by
the power of the steam-engine or water-wheel.

Grinding wheels or grinding mills are divided into a number of separate
rooms; every room contains six places called troughs; each trough
consists of a convenience for running a grindstone and a polisher at the
same time, which is generally occupied by a man and a boy.

The business of the grinder is generally divided into three stages, viz.
grinding, glazing, and polishing.

The grinding is performed upon stones of various qualities and sizes,
depending on the articles to be ground. Those exposing much flat
surface, such as saws, fenders, &c. require stones of great diameter,
while razors, whose surface is concave, require to be ground upon stones
of very small dimensions. Those articles which require a certain temper,
which is the case with most cutting instruments, are mostly ground on a
wet stone; for which purpose the stone hangs within the iron trough,
filled with water to such a height that its surface may just touch the
face of the stone.

Glazing is a process following that of grinding: it consists in giving
that degree of lustre and smoothness to an article which can be effected
by means of emery of the various degrees of fineness. The tool on which
the glazing is performed, is termed a glazer. It consists of a circular
piece of wood, formed of a number of pieces in such a manner that its
edge or face may always present the endway of the wood. Were it made
otherwise, the contraction of the parts would destroy its circular
figure. It is fixed upon an iron axis similar to that of the stone. Some
glazers are covered on the face with leather, others with metal,
consisting of an alloy of lead and tin; the latter are termed caps. In
others, the wooden surface above is made use of. Some of the
leather-faced glazers, such as are used for forks, table knives, edge
tools, and all the coarser polished articles, are first coated with a
solution of glue, and then covered with emery. The surfaces of the
others are prepared for use by first turning the face very true, then
filling it with small notches by means of a sharp-ended hammer, and
lastly filling up the interstices with a compound of tallow and emery.

The pulley of the glazer is so much less than that of the stone, that
its velocity is more than double, having in general a surface speed of
1500 feet in a second.

The process of polishing consists in giving the most perfect polish to
the different articles. Nothing is subjected to this operation but what
is made of cast steel, and has been previously hardened and tempered.

The polisher consists of a circular piece of wood covered with buff
leather, the surface of which is covered from time to time, while in
use, with the crocus of iron, called also colcothar of vitriol.

The polisher requires to run at a speed much short of that of the stone,
or the glazer. Whatever may be its diameter, the surface must not move
at a rate exceeding 70 or 80 feet in a second.


CYANATES; saline compounds of cyanic acid with the bases potash, soda,
ammonia, baryta, &c. The first is prepared by calcining at a dull red
heat, a mixture of ferro-cyanide of potassium (prussiate of potash) and
black oxide of manganese. The cyanates have not hitherto been applied to
any use in the arts.


CYANHYDRIC Acid; another name for the hydrocyanic or prussic acid. See
PRUSSIAN BLUE and PRUSSIC ACID.


CYANIDES; compounds of cyanogen with the metals; as cyanide of
potassium, sodium, barium, calcium, iron, mercury. The last is the only
one of importance in a manufacturing point of view, since from it
prussic acid is made.


CYANIDES, FERRO. Double compounds of cyanogen with iron, and of cyanogen
with another metal, such as potassium, sodium, barium, &c. The ordinary
yellow prussiate of potash has this constitution, and is called the
ferro-cyanide.


CYANOGEN. A gaseous compound of two prime equivalents of charcoal = 12,
and one of azote = 14 = 26; hydrogen being the radix or, 1. It consists
of two volumes of vapour of carbon, and one volume of azote, condensed
into one volume; and has therefore a density equal to the sum of the
weights of these 3 gaseous volumes = 1·815. Cyanogen is readily procured
by exposing the cyanide of mercury to a dull red heat in a retort; the
gas is evolved and may be collected over mercury. Its smell is very
sharp and penetrating; it perceptibly reddens tincture of litmus; it is
condensable by pressure at a low temperature into a liquid; and by a
still greater degree of cold, it is solidified. When a lighted taper is
applied to a mixture of cyanogen and oxygen, an explosion takes place;
carbonic acid is formed, and the azote is set at liberty.

For a connected view of the various compounds of cyanogen employed in
the arts, see PRUSSIAN BLUE.


CYDER; (_Cidre_, Fr.; _Apfelwein_, Germ.) the vinous fermented juice of
the apple. The ancients were acquainted with cyder and perry, as we
learn from the following passage of Pliny the naturalist: “Wine is made
from the Syrian pod, from pears and apples of every kind.” Book xiv.
chap. 19. The term cyder or cidre in French, at first written _sidre_,
is derived from the latin word _sicera_, which denoted all other
fermented liquors except grape wine. Cyder seems to have been brought
into Normandy by the Moors of Biscay, who had preserved the use of it
after coming into that country from Africa. It was afterwards spread
through some other provinces of France, whence it was introduced into
England, Germany, and Russia. It is supposed that the first growths of
Normandy afford still the best specimens of cyder. Devonshire and
Herefordshire are the counties of England most famous for this beverage.

Strong and somewhat elevated ground, rather dry, and not exposed to the
air of the sea, or to high winds, are the best situations for the growth
of the cyder apple. The fruit should be gathered in dry weather. The
juice of apples is composed of a great deal of water; a little sugar
analogous to that of the grape; a matter capable of causing fermentation
with contact of air; a pretty large proportion of mucilage, with malic
acid, acetic acid, and an azotized matter in a very small quantity. The
seeds contain a bitter substance and a little essential oil; the pure
parenchyma or cellular membrane constitutes not more than two per cent.
of the whole. After the apples are gathered, they are left in the
barn-loft for fifteen days or upwards to mellow; some of them in this
case, however, become soft and brown. This degree of maturation
diminishes their mucilage, and developes alcohol and carbonic acid; in
consequence of which the cyder suffers no injury. There is always
however a little loss; and if this ripening goes a little further it is
very apt to do harm, notwithstanding the vulgar prejudice of the country
people to the contrary. Too much care, indeed, cannot be taken to
separate the sound from the spoiled apples; for the latter merely
furnish an acid leaven, give a disagreeable taste to the juice, and
hinder the cyder from fining, by leaving in it a certain portion of the
parenchyma, which the gelatinous matter or the fermentation has diffused
through it. Unripe apples should be separated from the ripe also, for
they possess too little saccharum to be properly susceptible of the
vinous fermentation.

In France, where cyder making is most scientifically practised, it is
prepared by crushing the apples in a mill with revolving edge-stones,
turned in a circular stone cistern by one or two horses. When the fruit
is half mashed, about one fifth of its weight of river water is added,
or the water of lakes. The latter have been found by experience to be
preferable to other water.

In some places a mill composed of two cast-iron fluted cylinders placed
parallel to each other under the bottom of a hopper, is employed for
crushing the apples. One of the cylinders is turned by a winch, and
communicates its motion in the opposite direction by means of the
flutings working into each other. Each portion of the fruit must be
passed thrice through this rude mill in order to be sufficiently mashed;
and the same quantity of water must be added as in the edge stone mill.

After the apples are crushed they are usually put into a large tub or
tun for 12 or 24 hours. This steeping aids the separation of the juice,
because the fermentative motion which takes place in the mass breaks
down the cellular membranes; but there is always a loss of alcohol
carried off by the carbonic acid disengaged, while the skins and seeds
develope a disagreeable taste in the liquid. The vatting might be
suppressed if the apples were so comminuted as to give out their juice
more readily. With slight modifications, the process employed in rasping
and squeezing the beet-roots might in my opinion be applied with great
advantage to the cyder manufacture. See SUGAR.

After the vatting, the mashed fruit is carried to the press and put upon
a square wicker frame or into a hair bag, sometimes between layers of
straw, and exposed stratum super stratum to strong pressure till what is
called a cheese or cake is formed. The mass is to be allowed to drain
for some time before applying pressure, which ought to be very gradually
increased. The juice which exudes with the least pressure affords the
best cyder; that which flows towards the end acquires a disagreeable
taste from the seeds and the skins. The must is put into casks with
large bungholes, where it soon begins to exhibit a tumultuous
fermentation. The cask must be completely filled, in order that all the
light bodies suspended in the liquid when floated to the top by the
carbonic acid may flow over with the froth; this means of clearing cyder
is particularly necessary with the weak kinds, because it cannot be
expected that these matters in suspension will fall to the bottom of the
casks after the motion has ceased. In almost every circumstance besides,
when no saccharine matter has been added to the must, that kind of yeast
which rises to the top must be separated, lest by precipitation it may
excite an acid fermentation in the cyder. The casks are raised upon
gawntrees or stillions, in order to place flat tubs below them to
receive the liquor which flows over with the froth. At the end of two or
three days, for weak cyders which are to be drunk somewhat sweet, of 6
or 10 days or more for stronger cyders, with variations for the state of
the weather, the fermentation will be sufficiently advanced, and the
cyder may be racked off into other casks. Spirit puncheons preserve
cyder better than any other, but in all cases the casks should be well
seasoned and washed. Sometimes a sulphur match is burned in them before
introducing the cyder, a precaution to be generally recommended, as it
suspends the activity of the fermentation, and prevents the formation of
vinegar.

The cyder procured by the first expression is called cyder without
water. The cake remaining in the press is taken out, divided into small
pieces, and mashed anew, adding about half the weight of water, when the
whole is carried back to the press and treated as above described. The
liquor thus obtained furnishes a weaker cyder which will not keep, and
therefore must be drunk soon.

The cake is once more mashed up with water, and squeezed, when it yields
a liquor which may be used instead of water for moistening fresh ground
apples.

The processes above described, although they have been long practised,
and have therefore the stamp of ancestral wisdom, are extremely
defective. Were the apples ground with a proper rotatory rasp which
would tear all their cells asunder, and the mash put through the
hydraulic press in bags between hurdles of wicker-work, the juice would
be obtained in a state of perfection fit to make a cyder superior to
many wines. An experimental process of this kind has been actually
executed in France upon a considerable scale, with the best results. The
juice had the fine flavour of the apple, was fermented by itself without
any previous fermentation in the mash, and afforded an excellent strong
cyder which kept well.

When the must of the apples is weak or sour, good cyder cannot be made
from it without the addition of some saccharine matter. The syrup into
which potato farina is convertible by _diastase_ (saccharine ferment),
see STARCH and SUGAR, would answer well for enriching poor apple juice.




D.


DAHLINE, the same as Inuline, the fecula obtained from elecampane,
analogous in many respects to starch. It is not employed in the arts.


DAMASCUS BLADES, are swords or scymitars, presenting upon their surface
a variegated appearance of _watering_, as white, silvery, or black
veins, in fine lines, or fillets; fibrous, crossed, interlaced or
parallel, &c. They are brought from the East, being fabricated chiefly
at Damascus, whence their name. Their excellent quality has become
proverbial; for which reason these blades are much sought after by
military men, and are high priced. The oriental processes have never
been satisfactorily described; but of late years methods have been
devised in Europe to imitate the fabric very well.

Clouet and Hachette pointed out the three following processes for
producing Damascus blades: 1, that of _parallel fillets_; 2, that by
_torsion_; 3, the _mosaic_. The first, which is still pursued by some
French cutlers, consists in scooping out with a graving tool the faces
of a piece of stuff composed of thin plates of different kinds of steel.
These hollows are by a subsequent operation filled up, and brought to a
level with the external faces, upon which they subsequently form
tress-like figures. 2. The method of torsion, which is more generally
employed at present, consists in forming a bundle of rods or slips of
steel, which are welded together into a well-wrought bar, twisted
several times round its axis. It is repeatedly forged, and twisted
alternately; after which it is slit in the line of its axis, and the two
halves are welded with their outsides in contact; by which means their
faces will exhibit very various configurations. 3. The mosaic method
consists in preparing a bar, as by the torsion plan, and cutting this
bar into short pieces of nearly equal length, with which a faggot is
formed and welded together; taking care to preserve the sections of each
piece at the surface of the blade. In this way, all the variety of the
design is displayed, corresponding to each fragment of the cut bar.

The blades of Clouet, independently of their excellent quality, their
flexibility, and extreme elasticity, have this advantage over the
oriental blades, that they exhibit in the very substance of the metal,
designs, letters, inscriptions, and, generally speaking, all kinds of
figures which had been delineated beforehand.

Notwithstanding these successful results of Clouet, it was pretty clear
that the watered designs of the true Damascus scymitar were essentially
different. M. Bréant has at last completely solved this problem. He has
demonstrated that the substance of the oriental blades is a cast-steel
more highly charged with carbon than our European steels, and in which,
by means of a cooling suitably conducted, a crystallization takes place
of two distinct combinations of carbon and iron. This separation is the
essential condition; for if the melted steel be suddenly cooled in a
small crucible or ingot, there is no damascene appearance.

If an excess of carbon be mixed with iron, the whole of the metal will
be converted into steel; and the residuary carbon will combine in a new
proportion with a portion of the steel so formed. There will be two
distinct compounds; namely, pure steel, and carburetted steel or
cast-iron. These at first being imperfectly mixed will tend to separate,
if while still fluid they be left in a state of repose; and form a
crystallization in which the particles of the two compounds will place
themselves in the crucible in an order determined by their affinity and
density conjoined. If a blade forged out of steel so prepared be
immersed in acidulous water, it will display a very distinct damascus
appearance; the portions of pure steel becoming black, and those of
carburetted steel remaining white, because the acids with difficulty
disengage its carbon. The slower such a compound is cooled, the larger
the damascus veins will be. Travernier relates that the steel crucible
ingots, like those of wootz, for making the true oriental damascus, come
from Golconda, that they are of the size of a halfpenny roll, and when
cut in two, form two swords.

Steel combined with manganese forges easily, but it is brittle when
cold; it displays however the damascus appearance very strongly.

A mixture of 100 parts of soft iron, and 2 of lamp black, melts as
readily as ordinary steel. Several of the best blades which M. Bréant
presented to the Société d’Encouragement are the product of this
combination. This is an easy way of making cast-steel without previous
cementation of the iron. 100 parts of filings of very gray cast-iron,
and 100 parts of like filings previously oxidized, produced, by their
fusion together, a beautiful damascene steel, fit for forging into white
arms, sabres, swords, &c. This compound is remarkable for its
elasticity, an essential quality, not possessed by the old Indian steel.
The greater the proportion of the oxidized cast iron, the tougher is the
steel. Care should be taken to stir the materials during their fusion,
before it is allowed to cool; otherwise they will not afford a
homogeneous damasc. If the steel contains much carbon it is difficult to
forge, and cannot be drawn out except within a narrow range of
temperature. When heated to a red-white it crumbles under the hammer; at
a cherry-red it becomes hard and brittle; and as it progressively cools
it becomes still more unmalleable. It resembles completely Indian steel,
which European blacksmiths cannot forge, because they are ignorant of
the suitable temperature for working it. M. Bréant, by studying this
point, succeeded in forging fine blades.

Experience has proved that the orbicular veins, called by the workmen
_knots_ or _thorns_ (_ronces_), which are seen upon the finest Eastern
scymitars, are the result of the manner of forging them, as well as the
method of twisting the Damascus bars. If these be drawn in length, the
veins will be longitudinal; if they be spread equally in all
directions, the stuff will have a crystalline aspect; if they be made
wavy in the two directions, undulated veins will be produced like those
in the oriental damascus.


DAMASK is a variegated textile fabric, richly ornamented with figures of
flowers, fruits, landscapes, animals, &c., woven in the loom, and is by
far the most rich, elegant, and expensive species of ornamental weaving,
tapestry alone excepted. The name is said to be derived from Damascus,
where it was anciently made.

Damask belongs to that species of texture which is distinguished by
practical men by the name of tweeling, of which it is the richest
pattern. The tweel of damask is usually half that of full _satin_, and
consequently consists of eight leaves moved either in regular succession
or by regular intervals, eight leaves being the smallest number which
will admit of alternate tweeling at equal intervals.

In the article CARPET, two representations have been given of the damask
draw-loom.

The generic difference of tweeling, when compared with common cloth,
consists in the intersections, although uniform and equidistant, being
at determinate intervals, and not between the alternate threads. Hence
we have specimens of tweeled cloth, where the intersections take place
at the third, fourth, fifth, sixth, seventh, eighth, or sixteenth
interval only. The threads thus deflecting only from a straight line at
intervals, preserve more of their original direction, and a much greater
quantity of materials can be combined in an equal space, than in the
alternate intersection, where the tortuous deflection, at every
interval, keeps them more asunder. On this principle tweeled cloths of
three and four leaves are woven for facility of combination alone. The
coarser species of ornamented cloths, known by the names of dornock and
diaper, usually intersect at the fifth, or half satin interval. The
sixth and seventh are rarely used, and the intersection at the eighth is
distinguished by the name of satin in common, and of damask in
ornamental tweeling. It will further be very obvious, that where the
warp and woof cross only at every eighth interval, the two sides of the
cloth will present a diversity of appearance; for on one side the
longitudinal or warp threads will run parallel from one end of a web to
the other, and, on the other, the threads of woof will run also
parallel, but in a transverse direction across the cloth, or at right
angles to the former. The points of intersection being only at every
eighth interval, appear only like points; and in regular tweeling these
form the appearance of diagonal lines, inclined at an angle of 45° (or
nearly so) to each of the former.

The appearance, therefore, of a piece of common tweeled cloth is very
similar to that of two thin boards glued together, with the grain of the
upper piece at right angles to that of the under one. That of an
ornamental piece of damask may, in the same manner, be very properly
assimilated to a piece of veneering, where all the wood is of the same
substance and colour, and where the figures assume a diversity of
appearance from the ground, merely by the grain of the one being
disposed perpendicularly to that of the other. See TEXTILE FABRIC.

From this statement of the principle, it results that the most unlimited
variety of figures will be produced, by constructing a loom by which
every individual thread of warp may be placed either above or below the
woof at every intersection; and to effect this, in boundless variety, is
the object of the Jacquard mounting; which see.

The chief seat of this manufacture is probably the town and
neighbourhood of Dunfermline, in Fifeshire, and Lisburn and Ardoyne,
near Belfast, where it is considered as the staple, having proved a very
profitable branch of traffic to the manufacturer, and given employment
to many industrious people.

The material used there is chiefly linen; but many have been recently
woven of cotton, since the introduction of that article into the
manufacture of cloth has become so prevalent. The cotton damasks are
considerably cheaper than those of linen; but are not considered either
so elegant or durable. The cotton, also, unless frequently bleached,
does not preserve the purity of the white colour nearly so well as the
linen.


DAMASKEENING; the art of ornamenting iron, steel, &c., by making
incisions upon its surface, and filling them up with gold or silver
wire; chiefly used in enriching sword blades, guards, and gripes, locks
of pistols, &c.

Its name shows the place of its origin, or, at least, the place where it
has been practised in the greatest perfection; viz. the city of
Damascus, in Syria; though M. Felibien attributes the perfection of the
art to his countryman, Cursinet, who wrought under the reign of Henry
IV.

Damaskeening is partly mosaic work, partly engraving, and partly
carving. As mosaic work, it consists of pieces inlaid; as engraving, the
metal is indented, or cut in intaglio; and as carving, gold and silver
are wrought into it in _relievo_.

There are two ways of damaskeening; in the first, which is the most
beautiful, the artists cut into the metal with a graver, and other tools
proper for engraving upon steel, and afterwards fill up the incisions,
or notches, with a pretty thick silver or gold wire. In the other, which
is only superficial, they content themselves to make hatches, or
strokes across the iron, &c. with a cutting knife, such as is used in
making of small files. As to the first, it is necessary for the gravings
or incisions to be made in the dove-tail form; that the gold or silver
wire, which is thrust forcibly into them, may adhere the more strongly.
As to the second, which is the more usual, the method is this:--Having
heated the steel till it changes to a violet, or blue colour, they hatch
it over and across with the knife; then draw the ensign or ornament
intended, upon this hatching, with a fine brass point or bodkin. This
done, they take fine gold wire, and conducting or chasing it according
to the figures already designed, they sink it carefully into the hatches
of the metal with a copper tool.


DAMASSIN is a kind of damask, with gold and silver flowers, woven in the
warp and woof; or occasionally with silk organzine.


DAMPS, in mining, are noxious exhalations, or rather gases, so called
from the German _dampf_, vapour. There are two principal kinds of mine
gases, the _fire-damp_, or carburetted hydrogen, and the _choke-damp_,
or carbonic acid gas. See MINES.


DAPHNINE; the bitter principle of the _Daphne Alpina_.


DATOLITE. A mineral composed of silica, lime, and boracic acid.


DECANTATION, (Eng. and Fr.; _Abgiessen_, Germ.) is the act of pouring
off the clear supernatant fluid from any sediment or deposit. It is much
employed in the chemical arts; and is most conveniently effected by a
syphon.


DECOCTION, (Eng. and Fr.; _Abkochung_, Germ.) means either the act of
boiling a liquid along with some organic substance, or the liquid
compound resulting from that act.


DECOMPOSITION, (Eng. and Fr.; _Zersetzung_, Germ.) is the separation of
the constituent principles of any compound body. The following table,
the result of important researches recently made by M. Persoz, Professor
of Chemistry at Strasburgh, shows the order in which decompositions take
place among the successive substances.

     Nitric Acid.          Muriatic Acid.

  Oxide of Magnesium    Oxide of Magnesium
   --      Silver        --      Cobalt
   --      Cobalt        --      Nickel
   --      Nickel       Protox. of Mercury
  Protox. of Cerium      --      Cerium
  Oxide of Zinc         Oxide of Zinc
  Protox. of Manganese  Protox. of Manganese
  Oxide of Lead          --      Iron
   --      Cadmium       --      Uranium
   --      Copper        --      Copper
   --      Glucinum              Tin
   --      Alumium      Oxide of Glucinum
   --      Uranium       --      Alumium
   --      Chromium      --      Uranium
  Protox. of Mercury     --      Chromium
  Oxide of Mercury       --      Iron
   --      Iron          --      Tin
   --      Bismuth       --      Bismuth
                         --      Antimony

By means of the cupric oxide we may separate, 1, the ferric oxide from
the manganous oxide; 2, the cobaltic, nickelic, zincic and cerous oxides
from the uranic, ferric, chromic, and aluminic oxides; 3, the ferrous
oxide from the chromic oxide, when dissolved in the muriatic acid.

In boiling a muriatic solution of the cobaltic, nickelic, and manganous
oxides, with the mercuric oxide, the first two oxides alone are
precipitated. Alumina separates the cadmic oxide from the bismuthic
oxide, the stannous oxide from the stannic oxide, and the stannous oxide
from the antimonic acid. The cupric oxide separates also by
precipitation, the aluminic, uranic, chromic, titanic, and vanadic
oxides from all the oxides which are precipitable in the state of
sulphuret, by hydrosulphuret of ammonia.

As an example of this mode of analysis--

Dissolve pech-blende in aqua regia, precipitate its copper by
sulphuretted hydrogen, boil the liquid along with nitric acid, in order
to transform all the uranium into uranic acid. Next boil it along with
cupric oxide, which precipitates only the uranic and ferric oxides.
Redissolve the precipitate in nitric acid, and boil the solution with
mercuric oxide, which does not precipitate the ferric oxide. Finally,
separate the copper and the mercury from the uranium, by means of
sulphuretted hydrogen. In this process we may substitute plumbic oxide
for the cupric oxide, and succeed equally well.

Knowledge, like the above, of the elective affinities and habitudes of
chemical bodies, simple and compound, imparts to its possessor an
irresistible power over the unions and disunions of the elements, which
he can exercise with certainty in effecting innumerable transformations
in the arts.


DECREPITATION, (Eng. and Fr.; _Verknistern_, Germ.) is the crackling
noise, attended with the flying asunder of their parts, made by several
salts and minerals, when heated. It is caused by the unequal sudden
expansion of their substance by the heat. Sulphate of baryta, chloride
of sodium, calcareous spar, nitrate of baryta, and many more bodies
which contain no water, decrepitate most violently, separating at the
natural joints of their crystalline structure. Some chemists have
preposterously enough ascribed the phenomenon to the expansion of the
combined water into steam. What a specimen of inductive philosophy!


DEFECATION, (Eng. and Fr.; _Klaren_, Germ.) the freeing from dregs or
impurities.


DEFLAGRATION, (Eng. and Fr.; _Verpuffung_, Germ.) the sudden blazing up
of a combustible; as of a charcoal or sulphur when thrown into melted
nitre.


DELPHINIA. The vegeto-alkaline principle of the _Delphinium
staphysagria_, or stavesacre. It is poisonous.


DELIQUESCENT, (_Zerfliessen_, Germ.) is said of a solid which attracts
so much moisture from the air as to become spontaneously soft or liquid;
such as potash and muriate of lime.


DEPHLEGMATION is the process by which liquids are deprived of their
watery particles. It is applied chiefly to spirituous liquors, and is
now nearly obsolete, as involving the alchemistical notion of a peculiar
principle called phlegm.


DEPHLOGISTICATED; deprived of phlogiston,--formerly supposed to be the
common combustible principle. It is nearly synonymous with oxygenated.
The idea originally attached to the word having proceeded from false
logic, the word itself should never be used either in science or
manufactures.


DEPILATORY. (_Depilatoire_, Fr.; _Enthaarensmittel_, Germ.) is the name
of any substance capable of removing hairs from the human skin without
injuring its texture. They act either mechanically or chemically. The
first are commonly glutinous plasters formed of pitch and rosin, which
stick so closely to the part of the skin where they are applied, that
when removed, they tear away the hairs with them. This method is more
painful, but less dangerous than the other, which consists in the
solvent action of a menstruum, so energetic as to penetrate the pores of
the skin, and destroy the bulbous roots of the hairs. This is composed
either of caustic alkalis, sulphuret of baryta, or arsenical
preparations. Certain vegetable juices have also been recommended for
the same purpose; as spurge and acacia. The bruised eggs of ants have
likewise been prescribed. But the _oriental rusma_ yields to nothing in
depilatory power. Gadet de Gassincourt has published in the
_Dictionnaire des Sciences Medicales_, the following recipe for
preparing it.

Mix two ounces of quicklime, with half an ounce of orpiment or realgar,
(sulphuret of arsenic;) boil that mixture in one pound of strong
alkaline lye, then try its strength by dipping a feather into it, and
when the flue falls off, the _rusma_ is quite strong enough. It is
applied to the human skin by a momentary friction, followed by washing
with warm water. Such a caustic liquid should be used with the greatest
circumspection, beginning with it somewhat diluted. A soap is sometimes
made with lard and the above ingredients; or soft soap is combined with
them; in either case to form a depilatory pommade. Occasionally one
ounce of orpiment is taken to eight ounces of quicklime, or two to
twelve, or three to fifteen; the last mixture being of course the most
active. Its causticity may be tempered by the addition of one eighth of
starch or rye flour, so as to form a soft paste, which being laid upon
the hairy spot for a few minutes, usually carries away the hairs with
it.

The _rusma_ should never be applied but to a small surface at a time,
for independently of the risk of corroding the skin, dangerous
consequences might ensue from absorption of the arsenic.


DETONATION. See FULMINATING, for the mode of preparing detonating powder
for the percussion caps of fire-arms.


DEUTOXIDE literally means the second oxide, but is usually employed to
denote a compound containing two atoms or two prime equivalents of
oxygen to one or more of a metal. Thus we say deutoxide of copper, and
deutoxide of mercury. Berzelius has abbreviated this expression by
adopting the principles of the French nomenclature of 1787; according to
which the higher stage of oxidizement is characterized by the
termination _ic_, and the lower by _ous_, and he writes accordingly
cupric and mercuric, to designate the deutoxides of these two metals;
cuprous and mercurous to designate their protoxides. I have adopted this
nomenclature in the article DECOMPOSITION, and in some other parts of
this Dictionary, as being short and sufficiently precise.


DEXTRINE, is a matter of a gummy appearance into which the interior
substance of the molecules of starch are converted, through the
influence of diastase or acids. It derives its name from the
circumstance that it turns, more than any other body, the plane of
polarization to the right hand. It is white, insipid, without smell,
transparent in thin plates, friable, with a glassy fracture when well
dried. It is not altered by the heat of boiling water, but at 280° F. it
becomes brown, and acquires the flavour of toasted bread. It is not
coloured by iodine, like starch, it does not form muric acid with the
nitric, as common gum does, and it is transformed into grape sugar, when
heated along with dilute sulphuric acid or diastase.

Dextrine is much employed by the French pastrycooks and confectioners;
it is a good substitute for gum arabic in medicine. For the conversion
of potato or other starch into dextrine, by the action of diastase, see
this article.


DIAMOND. Since this body is merely a condensed form of carbon, it cannot
in a chemical classification be ranked among stones; but as it forms in
commerce the most precious of the gems, it claims our first attention in
a practical treatise on the arts. Diamonds are distinguishable by a
great many peculiar properties, very remarkable and easily recognized,
both in their rough state, and when cut and polished. Their most
absolute and constant character is a degree of hardness superior to that
of every mineral, whence diamonds scratch all other bodies, and are
scratched by none. Their peculiar adamantine lustre, not easy to define,
but readily distinguishable by the eye from that of every other gem, is
their most obvious feature. Their specific gravity is 3·55. Whether
rough or polished, diamonds acquire by friction, positive electricity,
but do not retain it for more than half an hour. The natural form of
diamonds is derivable from an octahedron, and they never present
crystals having one axis longer than the other. Their structure is very
perceptibly lamellar, and therefore, notwithstanding their great
hardness, they are brittle and give way in the line of their cleavage,
affording a direct means of arriving at their primitive form, the
regular octahedron.

The diamond possesses either single or double refraction, according to
its different crystalline forms; its refractive power on light is far
greater than it ought to be in the ratio of its density; the index of
refraction being 2·44, whence Newton long ago supposed it to consist of
inflammable matter. Its various forms in nature present a circumstance
peculiar to this body; its faces are rarely terminated by planes, like
most other native crystals, but they are often rounded off, and the
edges between them are curved. When these secondary faces are
attentively examined with a lens, we remark that they are marked with
striæ, sometimes very fine and almost imperceptible, but at others well
defined; and that these striæ are parallel to the edges of the
octahedron, and consequently to those of the plates that are applied on
the primitive faces of this figure.

Diamonds are usually colourless and transparent; when coloured, their
ordinary tint verges upon yellow, or smoke-yellow, approaching sometimes
to blackish-brown. Green diamonds are next to yellow the most common;
the blue possess rarely a lively hue, but they are much esteemed in
Scotland. The rose or pink diamonds are the most valued of the coloured
kind, and exceed sometimes in price the most limpid; though generally
speaking the latter are the most highly prized.

The geological locality of the diamond seems to be in diluvial gravel,
and among conglomerate rocks; consisting principally of fragments of
quartz, or rolled pebbles of quartz mixed with ferruginous sand, which
compose sometimes hard aggregated masses. This kind of formation is
called _cascalho_ in Brazil. Its accompanying minerals are few in
number, being merely black oxide of iron, micaceous iron ore, pisiform
iron ore, fragments of slaty jasper, several varieties of quartz,
principally amethyst. In Mr. Heuland’s splendid collection there was a
Brazilian diamond imbedded in brown iron ore; another in the same,
belonging to M. Schuch, librarian to the Crown Princess of Portugal; and
in the cabinet of M. Eschwege there is a mass of brown iron ore,
containing a diamond in the drusy cavity of a green mineral, conjectured
to be arseniate of iron. From these facts it may be inferred with much
probability that the matrix or original repository of the diamond of
Brazil is brown iron ore, which occurs in beds of slaty quartzose
micaceous iron ore, or in beds composed of iron-glance and magnetic iron
ore, both of which are apparently subordinate in that country to
primitive clay slate.

The loose earth containing diamonds lies always a little way beneath the
surface of the soil, towards the lower outlet of broad valleys, rather
than upon the ridges of the adjoining hills.

Only two _places_ on the earth can be adduced with certainty, as diamond
mines, or rather districts; a portion of the Indian peninsula, and of
Brazil.

India has been celebrated from the most remote antiquity as the country
of diamonds. Its principal mines are in the kingdoms of Golconda and
Visapour, extending from Cape Comorin to Bengal, at the foot of a chain
of mountains called the _Orixa_, which appear to belong to the trap rock
formation. In all the Indian diamond soils, these gems are so dispersed,
that they are rarely found directly, even in searching the richest
spots, because they are enveloped in an earthy crust, which must be
removed before they can be seen. The stony matter is therefore broken
into pieces, and is then, as well as the looser earth, washed in basins
scooped out on purpose. The gravel thus washed is collected, spread out
on a smooth piece of ground, and left to dry. The diamonds are now
recognized by their sparkling in the sun, and are picked out from the
stones.

The diamond mines of Brazil were discovered in 1728, in the district of
Serro-do-Frio. The ground in which they are imbedded has the most
perfect resemblance to that of the East Indies, where the diamonds
occur. It is a solid or friable conglomerate, consisting chiefly of a
ferruginous sand, which encloses fragments of various magnitude of
yellow and bluish quartz, of schistose jasper, and grains of gold
disseminated with oligist iron ore; all mineral matters different from
those that constitute the neighbouring mountains; this conglomerate, or
species of pudding-stone, almost always superficial, occurs sometimes at
a considerable height on the mountainous table-land. The most celebrated
diamond mine is that of Mandarga, on the Jigitonhonha, in the district
of Serro-do-Frio to the north of Rio-Janeiro. The river Jigitonhonha,
three times broader than the Seine at Paris, and from 3 to 9 feet deep,
is made nearly dry, by drawing the waters off with sluices at a certain
season; and the _cascalho_ or diamond-gravel is removed from the channel
by various mechanical means, to be washed elsewhere at leisure. This
cascalho, the same as the matrix of the gold mines, is collected in the
dry season, to be searched into during the rainy; for which purpose it
is formed into little mounds of 15 or 16 tons weight each. The washing
is carried on beneath an oblong shed, by means of a stream of water
admitted in determinate quantities into boxes containing the cascalho. A
negro washer is attached to each box; inspectors are placed at regular
distances on elevated stools, and whenever a negro has found a diamond,
he rises up and exhibits it. If it weighs 17-1/2 carats, he receives his
liberty. Many precautions are taken to prevent the negroes from
secreting the diamonds. Each squad of workmen consists of 200 negroes,
with a surgeon and an almoner or priest.

The flat lands on either side of the river are equally rich in diamonds
over their whole surface, so that it becomes very easy to estimate what
a piece of ground not yet washed may produce.

It is said that the diamonds surrounded with a greenish crust, are of
the _first_ water, or are the most limpid when cut. The diamonds
received in the different mines of the district, are deposited once a
month in the treasury of Tejuco; and the amount of what was thus
delivered from 1801 to 1806, may be estimated at about 18 or 19 thousand
carats _per annum_.

On the banks of the torrent called Rio-Pardo, there is another mine of
diamonds. The ground presents a great many friable rocks of
pudding-stone, distributed in irregular strata. It is chiefly in the bed
of this stream, that masses of cascalho occur, peculiarly rich in
diamonds. They are much esteemed, particularly those of a greenish-blue
colour. The ores that accompany the diamond at Rio-Pardo differ somewhat
from those of the washing grounds of Mandanga, for they contain no
pisiform iron ore; but a great many pebbles of slaty jasper. This table
land seems to be very high, probably not less than 5500 feet above the
level of the sea.

Tocaya, a principal village of Minas-Novas, is 34 leagues to the
north-east of Tejuco, in an acute angle of the confluence of the
Jigitonhonha, and the Rio-Grande. In the bed of the streamlets which
fall westward into the Jigitonhonha, those rolled white topazes are
found which are known under the name of _minas-novas_ with _blue
topazes_, and aquamarine beryls. In the same country are found the
beautiful cymophanes or chrysoberyls so much prized in Brazil. And it is
from the cantons of Indaia and Abaite that the largest diamonds of
Brazil come; yet they have not so pure a water as those of the district
of Serro-do-Frio, but incline a little to the lemon yellow.

Diamonds are said to come also from the interior of the island of
Borneo, on the banks of the river Succadan, and from the peninsula of
Malacca.

It is known that many minerals become phosphorescent by heat, or
exposure to the sun’s light. Diamonds possess this property, but all not
in equal degree, and certain precautions must be observed to make it
manifest. Diamonds need to be exposed to the sunbeam for a certain time,
in order to become self-luminous; or to the blue rays of the prismatic
spectrum, which augment still more the faculty of shining in the dark.
Diamonds susceptible of phosphorescence exhibit it either after a heat
not raised to redness, or the electric discharge. They possess not only
a great refractive power in the mean ray of light, but a high dispersive
agency, which enables them to throw out the most varied and vivid
colours in multiplied directions.

Louis de Berquem discovered in 1476, the art of cutting diamonds by
rubbing them against one another, and of polishing them with their own
powder. These operations may be abridged by two methods: 1. by availing
ourselves of the direction of the laminæ of the diamond to split them in
that direction, and thus to produce several facets. This process is
called cleaving the diamond. Some, which appear to be _macle_ crystals,
resist this mechanical division, and are called _diamonds of nature_. 2.
by sawing the diamonds by means of a very delicate wire, coated with
diamond powder.

_Diamonds_ take precedence of every gem for the purposes of dress and
decoration; and hence the price attached to those of a pure water,
increases in so rapid a proportion, that beyond a certain term, there is
no rule of commercial valuation. The largest diamond that is known seems
to be that of the Rajah of Mattan, in the East Indies. It is of the
purest water, and weighs 367 carats, or at the rate of 4 grains to a
carat, upwards of 3 ounces troy. It is shaped like an egg, with an
indented hollow near the smaller end; it was discovered at Landak about
100 years ago; and though the possession of it has cost several wars, it
has remained in the Mattan family for 90 years. A governor of Batavia,
after ascertaining the qualities of the gem, wished to be the purchaser,
and offered 150,000 dollars for it, besides two war brigs with their
guns and ammunition, together with a certain number of great guns, and a
quantity of powder and shot. But this diamond possessed such celebrity
in India, and was regarded as a talisman involving the fortunes of the
Rajah and his family, that he refused to part with it at any price.

The diamond possessed in the time of the traveller Tavernier, by the
emperor of Mogul, a kingdom now no more, weighed 279 carats, and was
reckoned worth upwards of 400,000_l._ sterling. It was said to have lost
the half of its original weight in the cutting. After these prodigious
gems, the next are:--1. That of the emperor of Russia, bought by the
late empress Catherine, which weighs 193 carats. It is said to be of the
size of a pigeon’s egg, and to have been bought for 90,000_l._, besides
an annuity to the Greek merchant of 4000_l._ It is reported that the
above diamond formed one of the eyes of the famous statue of Sheringan,
in the temple of Brama, and that a French grenadier, who had deserted
into the Malabar service, found the means of robbing the pagoda of this
precious gem; and escaped with it to Madras, where he disposed of it to
a ship captain for 2,000_l._, who resold it to a Jew for 12,000_l._ From
him it was transferred for a large sum to the Greek merchant. 2. That of
the emperor of Austria, which weighs 139 carats, and has a slightly
yellowish hue. It has, however, been valued at 100,000_l._ 3. That of
the king of France, called the Regent or Pitt diamond, remarkable for
its form and its perfect limpidity. Although it weighs only 136 carats,
its fine qualities have caused it to be valued at 160,000_l._ though it
cost only 100,000_l._

The largest diamond furnished by Brazil, now in possession of the crown
of Portugal, weighs, according to the highest estimates, 120 carats. It
was found in the streamlet of Abaïte, in a clay-slate district.

The diamonds possessed of no extraordinary magnitude, but of a good form
and a pure water, may be valued by a certain standard rule. In a
brilliant, or rose-diamond of regular proportions, so much is cut away
that the weight of the polished gem does not exceed one half the weight
of the diamond in the rough state; whence the value of a cut diamond is
esteemed equal to that of a similar rough diamond of double weight,
exclusive of the cost of workmanship. The weight and value of diamonds
is reckoned by carats of 4 grains each; and the comparative value of two
diamonds of equal quality but different weights, is as the squares of
these weights respectively. The average price of rough diamonds that are
worth working, is about 2_l._ for one of a single carat; but as a
polished diamond of one carat must have taken one of 2 carats, its price
in the rough state is double the square of 2_l._, or 8_l._ Therefore, to
estimate the value of a wrought diamond, ascertain its weight in carats,
double that weight, and multiply the square of this product by 2_l._

  Hence, a wrought diamond of 1 carat is worth _£_ 8
                              2       --          32
                              3       --          72
                              4       --         128
                              5       --         200
                              6       --         288
                              7       --         392
                              8       --         512
                              9       --         612
                             10       --         800
                             20       --        3200,

beyond which weight the prices can no longer rise in this geometrical
progression, from the small number of purchasers of such expensive toys.
A very trifling spot or flaw of any kind, lowers exceedingly the
commercial value of a diamond.

Diamonds are used not only as decorative gems, but for more useful
purposes, as for cutting glass by the glazier, and all kinds of hard
stones by the lapidary.

On the structure of the glazier’s diamond, we possess some very
interesting observations and reflections by Dr. Wollaston. He remarks,
that the hardest substances brought to a sharp point scratch glass,
indeed, but do not cut it, and that diamond alone possessed that
property; which he ascribes to the peculiarity of its crystallization in
rounded faces, and curvilinear edges. For glass-cutting, those rough
diamonds are always selected which are sharply crystallized, hence
called diamond sparks; but cut diamonds are never used. The inclination
to be given to a set diamond in cutting glass is comprised within very
narrow limits; and it ought, moreover, to be moved in the direction of
one of its angles. The curvilinear edge adjoining the curved faces,
entering as a wedge into the furrow opened up by itself, thus tends to
separate the parts of the glass; and in order that the crack which
causes the separation of the vitreous particles may take place, the
diamond must be held almost perpendicular to the surface of the glass.
The Doctor proved this theory by an experiment. If, by suitable cutting
with the wheel, we make the edges of a spinel ruby, or corundum-telesie
(sapphire) curvilinear, and the adjacent faces curved, these stones will
cut glass as well as a glazier’s diamond, but being less hard than it,
they will not preserve this property so long. He found that upon giving
the surface of even a fragment of flint the same shape as that of the
cutting diamond, it acquired the same property; but, from its relative
softness, was of little duration. The depth to which the fissure caused
by the glazier’s diamond penetrates, does not seem to exceed the
two-hundredth of an inch.

I shall here introduce Mr. Milburn’s valuable observations on the choice
of rough diamonds, as published in his work on _Oriental Commerce_.

The colour should be perfectly crystalline, resembling a drop of clear
spring water, in the middle of which you will perceive a strong light,
playing with a great deal of spirit. If the coat be smooth and bright,
with a little tincture of green in it, it is not the worse, and seldom
proves bad, but if there is a mixture of yellow with green, then beware
of it; it is a soft greasy stone, and will prove bad.

If the stone has a rough coat, so that you can hardly see through it,
and the coat be white and look as if it were rough by art, and clear of
flaws or veins, and no blemish cast in the body of the stone, (which may
be discovered by holding it against the light) the stone will prove
good.

It often happens that a stone will appear of a reddish hue on the
outward coat, not unlike the colour of rusty iron, yet by looking
through it against the light, you may observe the heart of the stone to
be white (and if there be any black spots, or flaws, or veins in it,
they may be discovered by a true eye, although the coat of the stone be
the same), and such stones are generally good and clear.

If a diamond appears of a greenish bright coat, resembling a piece of
green glass, inclining to black, it generally proves hard, and seldom
bad; such stones have been known to have been of the first water, and
seldom worse than the second; but if any tincture of yellow seems to be
mixed with it, you may depend on its being a very bad stone.

All stones of a milky cast, whether the coat be bright or dull, if ever
so little inclining to a bluish cast, are naturally soft, and in danger
of being flawed in the cutting; and though they should have the good
fortune to escape, yet they will prove dead and milky, and turn to no
account.

All diamonds of cinnamon colour are dubious; but if of a bright coat
mixed with a little green, then they are certainly bad, and are
accounted among the worst of colours. You will meet with a great many
diamonds of a rough cinnamon-coloured coat, opaque; this sort is
generally very hard, and, when cut, contain a great deal of life and
spirit; but the colour is very uncertain; it is sometimes white,
sometimes brown, and sometimes of a fine yellow. Rough diamonds are
frequently _beamy_, that is look fair to the eye, yet are so full of
veins to the centre, that no art or labour can polish them. A good
diamond should never contain small spots of a white or gray colour of a
nebulous form; it should be free from small reddish and brownish grains,
that sometimes occur on their surface, or in their interior. A good
diamond should split readily in the direction of the cleavage; it
sometimes happens, however, that the folia are curved, as is the case in
twin crystals. When this happens, the stone does not readily cut and
polish, and is therefore of inferior value.

In the cut and polished gem, the thickness must always bear a certain
proportion to the breadth. It must not be too thin nor thick; for, when
too thin, it loses much of its fire, and appears not unlike glass.

The term _carat_ is said to be derived from the name of a bean, the
produce of a species of _erythina_, a native of the district of
Shangallas, in Africa; a famous mart of gold-dust. The tree is called
_kuara_, a word signifying sun in the language of the country; because
it bears flowers and fruit of a flame colour. As the dry seeds of this
pod are always of nearly uniform weight, the savages have used them from
time immemorial to weigh gold. The beans were transported into India, at
an ancient period, and have been long employed there for weighing
diamonds. The carat of the civilized world is, in fact, an imaginary
weight, consisting of 4 nominal grains, a little lighter than 4 grains
troy (_poids de marc_); it requires 74 carat grains and 1/16 to
equipoise 72 of the other.

In valuing a cut diamond, we must reckon that one half of its weight has
been lost in the lapidary’s hands; whence its weight in this state
should be doubled before we calculate its price by the general rule for
estimating diamonds. The French multiply by 48 the square of this
weight, and they call the product in francs the value of the diamond.
Thus, for example, a cut diamond of 10 carats would be worth (10 × 2)² ×
48 = 19,200 francs, or 768_l._, allowing only 25 francs to the pound
sterling.

The diamond mines of Brazil have brought to its government, from the
year 173~ till 1814, 3,023,000 carats; being at the average rate
annually of 36,000 carats, or a little more than 16 libs., weight. They
have not been so productive in the later years of that period; for,
according to Mr. Mawe, between 1801 and 1806, only 115,675 carats were
obtained, being 19,279 a year. The actual expenses incurred by the
government, during this interval, was 4,419,700 francs; and, deducting
the production in gold from the washings of the diamond gravel, or
_cascalho_, it is found that the rough diamonds cost in exploration, per
carat, 38 francs 20 c., or nearly 31_s._ British money. The contraband
is supposed to amount to one third of the above legitimate trade. Brazil
is almost the only country where diamonds are mined at the present day;
it sends annually to Europe from 25 to 30 thousand carats, or from 10 to
16-1/2 libs.


DIAMONDS, _cutting of_. Although the diamond is the hardest of all known
substances, yet it may be split by a steel tool, provided a blow be
applied; but this requires a perfect knowledge of the structure, because
it will only yield to such means in certain directions. This
circumstance prevents the workman from forming facettes or planes
generally, by the process of splitting; he is therefore obliged to
resort to the process of abrasion, which is technically called cutting.
The process of cutting is effected by fixing the diamond to be cut on
the end of a stick, or handle, in a small ball of cement, that part
which is to be reduced being left to project. Another diamond is also
fixed in a similar manner; and the two stones being rubbed against each
other with considerable force, they are mutually abraded, flat surfaces,
or facettes, being thereby produced. Other facettes are formed by
shifting the diamonds into fresh positions in the cement, and when a
sufficient number are produced, they are fit for polishing. The stones,
when cut, are fixed for this purpose, by imbedding them in soft solder,
contained in a small copper cup, the part, or facette, to be polished,
being left to protrude.

A flat circular plate of cast-iron is then charged with the powder
produced during the abrasion of the diamonds; and by this means a tool
is formed which is capable of producing the exquisite lustre so much
admired on a finely-polished gem. Those diamonds that are unfit for
working, on account of the imperfection of their lustre or colour, are
sold, for various purposes, under the technical name of Bort. Stones of
this kind are frequently broken in a steel mortar, by repeated blows,
until they are reduced to a fine powder, which is used to charge metal
plates, of various kinds, for the use of jewellers, lapidaries, and
others. Bort, in this state of preparation, is incapable of polishing
any gems; but it is used to produce flat surfaces on rubies and other
precious stones.

Fine drills are made of small splinters of bort, which are used for
drilling small holes in rubies, and other hard stones, for the use of
watch-jewellers, gold and silver wire-drawers, and others, who require
very fine holes drilled in such substances. These drills are also used
to pierce holes in china, where rivets are to be inserted; also for
piercing holes in artificial enamel teeth, or any vitreous substances,
however hard.


DIAMOND MICROSCOPES, were first suggested by Dr. Goring, and have been
well executed by Mr. Pritchard. Previous to grinding a diamond into a
spherical figure, it should be ground flat and parallel upon both sides,
that by looking through it, as opticians try flint glass, we may see
whether it has a double or triple refractive power, as many have, which
would render it useless as a lens. Among the 14 different crystalline
forms of the diamond, probably the octahedron and the cube are the only
ones that will give single vision. It will, in many cases, be advisable
to grind diamond lenses, plano-convex, both because this figure gives a
low spherical aberration, and because it saves the trouble of grinding
one side of the gem. A concave tool of cast iron, paved with diamond
powder, hammered into it by a hardened steel punch, was employed by Mr.
Pritchard. This ingenious artist succeeded in completing a double convex
of equal radii, of about 1/25 of an inch focus, bearing an aperture of
1/30 of an inch with distinctness upon opaque objects, and its entire
diameter upon transparent ones. This lens gives vision with a trifling
chromatic aberration; in other respects, like Dr. Goring’s Amician
reflector, but without its darkness, its light is said to be superior to
that of any compound microscope whatever, acting with the same power,
and the same angle of aperture. The advantage of seeing an object
without _aberration_ by the interposition of only a single magnifier,
instead of looking at a picture of it with an eye-glass, is evident. We
thus have a simple direct view, whereby we shall see more accurately and
minutely the real texture of objects.


DIAPER, is the name of a kind of cloth, used chiefly for table linen. It
is known among the French by the name of _toile fourré_, and is
ornamented with the most extensive figures of any kind of tweeled
cloth, excepting damask. The mounting of a loom for working diaper is,
in principle, much the same as a draw-loom, but the figures being less
extensive, the mounting is more simple, and is wrought entirely by the
weaver, without the aid of any other person. As tweeled cloths, of any
number of leaves, are only interwoven at those intervals when one of the
leaves is raised, the woof above, and the warp below, is kept floating
or flushed, until the intersection takes place. Of consequence, the
floating yarn above, appears across the fabric, and that below
longitudinally. This property of tweeled cloths is applied to form the
ornamental figures of all kinds of tweeled goods, merely by reversing
the floating yarn when necessary. In the simpler patterns, this is
effected by a few additional leaves of treddles; but when the range of
pattern becomes too great to render this convenient, an apparatus called
a _back harness_ is employed, and the cloth woven with this mounting is
called diaper. Diapers are generally five-leaf tweels, that is to say,
every warp floats under four threads of woof, and is raised, and of
course interwoven with the fifth. This is done either successively,
forming diagonals at 45° upon the cloth, or by intervals of two threads,
which is called the broken tweel. The latter is generally, if not
universally adopted in the manufacture of diaper. The reason of
preferring the broken to the regular tweel, where ornaments are to be
formed, is very obvious. The whole depending upon reversed flushing to
give the appearance of oblique or diagonal lines, through either, would
destroy much of the effect, and materially injure the beauty of the
fabric. The broken tweel, on the contrary, restores to the tweeled cloth
a great similarity of appearance to plain, or alternately interwoven
fabrics, and, at the same time, preserves the facility of producing
ornaments by reversing the flushing. The simplest kinds of reversed
tweels will be found described under TEXTILE FABRICS.


DIASTASE. This curious substance, extracted by water from crushed malt,
and precipitated from that infusion by alcohol, as is described under
FERMENTATION, has been made the subject of new researches by M. Guerin
Varry. The conclusions deducible from his interesting experiments are
the following:--

1. One part of diastase, dissolved in 30 parts of cold water, put with
408 parts of potato starch out of contact of air, did not exercise the
slightest action upon this substance in the course of 63 days, under a
temperature varying from 68° to 79° Fahr.

2. Two parts of diastase do not in the course of an hour, cause the
globules of three parts of starch to burst, at a temperature approaching
very nearly to that of the hot water which bursts them into a paste. It
follows that diastase acts no part in the process of germination,
towards eliminating the teguments of the starch, or transforming its
interior portion into sugar, and a gummy matter assimilated by plants.

3. Diastase liquefies and saccharifies the paste of starch without
absorption or disengagement of gas; a reaction which takes place equally
in vacuo, as in the open air.

4. 100 parts of starch made into a paste with 39 times their weight of
water, mixed with 6·13 parts of diastase dissolved in 40 parts of water,
and kept for an hour between 140° and 149° Fahr., afforded 86·91 parts
of sugar.

5. A paste containing 100 parts of starch, and 1393 parts of water, put
in contact with 12·25 parts of diastase dissolved in 367 parts of cold
water, having been maintained at 68° Fahr. during 24 hours, produced
77·64 parts of sugar.

6. The preceding experiment, repeated at the temperature of melting ice,
afforded at the end of 2 hours, 11·82 parts of sugar.

7. The most favourable proportions and circumstances for the production
of a great quantity of sugar, are a slight excess of diastase or barley
malt, (at least 25 per cent. of the latter), about 50 parts of water to
one of starch, and a temperature between 140° and 149° Fahr. It is of
the greatest consequence for the saccharification to take place as
speedily as possible, so that the sugar produced may not be left in
contact with much gummy matter (_dextrine_), in which case, the diastase
will not convert the latter into sugar. In fact, the liquefaction and
saccharification should proceed simultaneously.

8. The sugar of starch, prepared either with diastase, or sulphuric
acid, crystallizes in cauliflowers, or in prisms with rhomboidal facets.
It has the same composition as sugar of grapes.

9. Diastase even in excess does not saccharify the gummy matter
dissolved in the water along with the starch sugar, but when the gum is
insulated, it is convertible almost entirely into sugar.

10. Gum arabic, cane sugar, and beer yeast, suffer no change from
diastase.

11. A watery solution of diastase readily decomposes on keeping, either
in contact or out of contact of air.

12. When starch-sugar, whether obtained by means of diastase or
sulphuric acid, is submitted to the spirituous fermentation, the sum of
the weights of the alcohol, carbonic acid, and water of crystallization
of the sugar, is less than the weight of the sugar by about 3-1/2 per
cent. This difference proceeds in a great measure from the formation of
some acetic acid, lactic acid, volatile oil, and probably some other
unknown products in the act of fermentation.


DIMITY, is a kind of cotton cloth originally imported from India, and
now manufactured in great quantities in various parts of Britain,
especially in Lancashire. Dr. Johnson calls it _dimmity_, and describes
it as a kind of fustian. The distinction between fustian and dimity
seems to be, that the former designates a common tweeled cotton cloth of
a stout fabric, which receives no ornament in the loom, but is most
frequently dyed after being woven. Dimity is also a stout cotton cloth,
but not usually of so thick a texture; and is ornamented in the loom,
either with raised stripes or fancy figures, is seldom dyed, but usually
worn white, as for bed and bed-room furniture. The striped dimities are
the most common, they require less labour in weaving than the others;
and the mounting of the loom being more simple, and consequently less
expensive, they can be sold at much lower rates. See TEXTILE FABRICS,
for particular details of the plan of mounting them.


DIES FOR STAMPING, (_Coins_, Fr.; _Münzstempeln_, Germ.) The first
circumstance that claims particular attention in the manufacture of
dies, is the selection of the best kind of steel for the purpose, and
this must in some measure be left to the experience of the die-forger,
who, if well skilled in his art, will be able to form a tolerably
correct judgment of the fitness of the metal for the purpose, by the
manner in which it works upon the anvil. It should be rather
fine-grained than otherwise, and above all things perfectly even and
uniform in its texture, and free from spots and patches finer or coarser
than the general mass. But the very fine and uniform steel with a silky
fracture, which is so much esteemed for some of the purposes of cutlery,
is unfit for our present purpose, from the extreme facility with which
it acquires great hardness by pressure, and its liability to cracks and
flaws. The very coarse-grained, or highly crystalline steel, is also
equally objectionable; it acquires fissures under the die-press, and
seldom admits of being equally and properly hardened. The object,
therefore, is to select a steel of a medium quality as to fineness of
texture, not easily acted upon by dilute sulphuric acid, and exhibiting
an uniform texture when its surface is washed over with a little
aqua-fortis, by which its freedom from pins of iron, and other
irregularities of composition, is sufficiently indicated.

The best kind of steel being thus selected, and properly forged at a
high heat into the rough die, it is softened by very careful annealing,
and in that state, having been smoothed externally, and brought to a
table in the turning lathe, it is delivered to the engraver.

The process of annealing the die consists in heating it to a bright
cherry red, and suffering it to cool gradually, which is best effected
by bedding it in a crucible or iron pot of coarsely-powdered charcoal,
that of animal substances being generally preferred. In this operation
it is sometimes supposed that the die, or at least its superficial
parts, becomes super-carbonized, or highly-converted steel, as it is
sometimes called; but experience does not justify such an opinion, and I
believe the composition of the die is scarcely, certainly not
materially, affected by the process, for it does not remain long enough
in the fire for the purpose.

The engraver usually commences his labours by working out the device
with small steel tools, in intaglio; he rarely begins in relief (though
this is sometimes done); and having ultimately completed his design, and
satisfied himself of its general effect and correctness, by impressions
in clay, and dabs, or casts in type metal, the die is ready for the
important operation of hardening, which, from various causes, a few of
which I shall enumerate, is a process of much risk and difficulty; for
should any accident now occur, the labour of many months may be
seriously injured, or even rendered quite useless.

The process of hardening soft steel is in itself very simple, though not
very easily explained upon mechanical or chemical principles. We know by
experience, that it is a property of this highly valuable substance, to
become excessively hard, if heated and suddenly cooled; if, therefore,
we heat a bar of soft malleable and ductile steel red hot, and then
suddenly quench it in a large quantity of cold water, it not only
becomes hard, but fragile and brittle. But as a die is a mass of steel
of considerable dimensions, this hardening is an operation attended by
many and peculiar difficulties, more especially as we have at the same
time to attend to the careful preservation of the engraving. This is
effected by covering the engraved face of the die with a protecting
face, composed of fixed oil of any kind, thickened with powdered
charcoal: some persons add pipe-clay, others use a pulp of garlic, but
pure lamp-black and linseed oil answer the purpose perfectly. This is
thinly spread upon the work of the die, which, if requisite, may be
further defended by an iron ring; the die is then placed with its face
downwards in a crucible, and completely surrounded by powdered charcoal.
It is heated to a suitable temperature, that is, about cherry red, and
in that state is taken out with proper tongs, and plunged into a body of
cold water, of such magnitude as not to become materially increased in
temperature; here it is rapidly moved about, until all noise ceases, and
then left in the water till quite cool. In this process it should
produce a bubbling and hissing noise; if it pipes and sings, we may
generally apprehend a crack or fissure.

No process has been found to answer better than the above simple and
common mode of hardening dies, though others have had repeated and fair
trials. It has been proposed to keep up currents and eddies of cold
water in the hardening cistern, by means of delivery-pipes, coming from
a height; and to subject the hot die, with its face uppermost, to a
sudden and copious current of water, let upon it from a large pipe,
supplied from a high reservoir; but these means have not in any way
proved more successful, either in saving the die, or in giving it any
good qualities. It will be recollected, from the form of the die, that
it is necessarily only, as it were, case-hardened, the hardest strata
being outside, and the softer ones within, which envelope a core,
something in the manner of the successive coats of an onion; an
arrangement which we sometimes have an opportunity of seeing displayed
in dies which have been smashed by a violent blow.

The hardening having been effected, and the die being for the time safe,
some further steps may be taken for its protection; one of these
consists in a very mild kind of tempering, produced by putting it into
water, gradually raised to the boiling point, till heated throughout,
and then suffering it gradually to cool. This operation renders the die
less apt to crack in very cold weather. A great safeguard is also
obtained by thrusting the cold die into a red-hot iron ring, which just
fits it in that state, and which, by contracting as it cools, keeps its
parts together under considerable pressure, preventing the spreading of
external cracks and fissures, and often enabling us to employ a split or
die for obtaining punches, which would break to pieces without the
protecting ring.

If the die has been successfully hardened, and the protecting paste has
done its duty, by preserving the face from all injury and oxidizement,
or burning, as it is usually called, it is now to be cleaned and
polished, and in this state constitutes what is technically called a
MATRIX: it may of course be used as a multiplier of medals, coins, or
impressions, but it is not generally thus employed, for fear of
accidents happening to it in the coining press, and because the artist
has seldom perfected his work upon it in this state. It is, therefore,
resorted to for the purpose of finishing a PUNCH, or steel impression
for relief. For this purpose a proper block of steel is selected, of the
same quality, and with the same precautions as before, and being
carefully annealed, or softened, is turned like the matrix, perfectly
true and flat at the bottom, and obtusely conical at top. In this state,
its conical surface is carefully compressed by powerful and proper
machinery upon the matrix, which being very hard, soon allows it to
receive the commencement of an impression; but in thus receiving the
impression, it becomes itself so hard by condensation of texture as to
require during the operation to be repeatedly annealed, or softened,
otherwise it would split into small superficial fissures, or would
injure the matrix; much practical skill is therefore required in taking
this impression, and the punch, at each annealing, must be carefully
protected, so that the work may not be injured.

Thus, after repeated blows in the die-press, and frequent annealing, the
impression from the matrix is at length perfected, or brought completely
up, and having been retouched by the engraver, is turned, hardened, and
collared, like the matrix, of which it is now a complete impression in
relief, and, as we have before said, is called a punch.

This punch becomes an inexhaustible parent of dies, without further
reference to the original matrix; for now by impressing upon it plugs of
soft steel, and by pursuing with them an exactly similar operation to
that by which the punch itself was obtained, we procure impressions from
it to any amount, which of course are fac-similes of the matrix, and
these dies being turned, hardened, polished, and, if necessary,
tempered, are employed for the purposes of coinage.

The distinction between striking medals, and common coin, is very
essential, and the work upon the dies is accordingly adjusted to each.
Medals are usually in very high relief, and the effect is produced by a
succession of blows; and as the metal in which they are struck, be it
gold, silver, or copper, acquires considerable hardness at each stroke
of the press, they are repeatedly annealed during the process of
bringing them up. In a beautiful medal, which Mr. Wyon some time since
completed for the Royal Navy College, the obverse represents a head of
the King, in very bold relief; it required thirty blows of a very
powerful press to complete the impression, and it was necessary to
anneal each medal after every third blow, so that they went ten times
into the fire for that purpose. In striking a coin or medal, the lateral
spread of the metal, which otherwise would ooze out as it were from
between the dies, is prevented by the application of a steel collar,
accurately turned to the dimensions of the dies, and which, when left
plain, gives to the edge of the piece a finished and polished
appearance; it is sometimes grooved, or milled, or otherwise
ornamented, and occasionally lettered, in which case it is made in three
separate and moveable pieces, confined by a ring, into which they are
most accurately fitted, and so adjusted that the metal may be forced
into the letters by its lateral spread, at the same time that the coin
receives the blow of the screw-press.

Coins are generally completed by one blow of the coining-press. These
presses are worked in the Royal Mint by machinery, so contrived that
they shall strike, upon an average, sixty blows in a minute; the blank
piece, previously properly prepared and annealed, being placed between
the dies by part of the same mechanism.

The number of pieces which may be struck by a single die of good steel,
properly hardened and duly tempered, not unfrequently amounts at the
Mint to between three and four hundred thousand, but the average
consumption of dies is of course much greater, owing to the variable
qualities of steel, and to the casualties to which the dies are liable:
thus, the upper and lower die are often violently struck together, owing
to an error in the layer-on, or in that part of the machinery which
ought to put the blank into its place, but which now and then fails so
to do. This accident very commonly arises from the boy who superintends
the press neglecting to feed the hopper of the layer-on with blank
pieces. If a die is too hard, it is apt to break or split, and is
especially subject to fissures, which run from letter to letter upon the
edge. If too soft, it swells, and the collar will not rise and fall upon
it, or it sinks in the centre, and the work becomes distorted and
faulty. He, therefore, who supplies the dies for an extensive coinage,
has many accidents and difficulties to encounter. There are eight
presses at the Mint, frequently at work for ten hours each day, and the
destruction of eight pair of dies per day (one pair for each press) may
be considered a fair average result, though they much more frequently
fall short of, than exceed this proportion. It must be remembered, that
each press produces 3600 pieces per hour, but, making allowance for
occasional stoppages, we may reckon the daily produce of each press at
30,000 pieces; the eight presses therefore will furnish a diurnal
average of 240,000 pieces.


DIGESTER, is the name of a strong kettle or pot of small dimensions,
made very strong, and mounted with a safety valve in its top. Papin, the
contriver of this apparatus, used it for subjecting bones, cartilages,
&c. to the solvent action of high-pressure steam, or highly heated
water, whereby he proposed to facilitate their digestion in the stomach.
This contrivance is the origin of the French cookery pans, called
_autoclaves_, because the lid is self-keyed, or becomes steam-tight by
turning it round under clamps or ears at the sides, having been
previously ground with emery to fit the edge of the pot exactly. In some
autoclaves the lid is merely laid on with a fillet of linen as a lute,
and then secured in its place by means of a screw bearing down upon its
centre from an arched bar above. The safety valve is loaded either by a
weight placed vertically upon it, or by of a lever of the second kind
pressing near its fulcrum, and acted upon by a weight which may be made
to bear upon any point of its graduated arm.

Chevreul has made a useful application of the digester to vegetable
analysis. His instrument consists of a strong copper cylinder, into
which enters a tight cylinder of silver, having its edge turned over at
right angles to the axis of the cylinder, so as to form the rim of the
digester. A segment of a copper sphere, also lined with silver stops the
aperture of the silver cylinder, being applied closely to its rim. It
has a conical valve pressed with a spiral spring, of any desired force,
estimated by a steelyard. This spring is enclosed within a brass box
perforated with four holes; which may be screwed into a tapped orifice
in the top of the digester. A tube screwed into another hole serves to
conduct away the condensable vapours at pleasure into a Woulfe’s
apparatus.


DISTILLATION, (Eng. and Fr.; _Branntweinbrennerei_, Germ.) means, in the
commercial language of this country, the manufacture of intoxicating
spirits; under which are comprehended the four processes, of _mashing_
the vegetable materials, _cooling_ the worts, exciting the vinous
_fermentation_, and separating by a peculiar vessel called a _still_,
the alcohol combined with more or less water. This art of evoking the
fiery demon of drunkenness from his attempered state in wine and beer,
was unknown to the ancient Greeks and Romans. It seems to have been
invented by the barbarians of the north of Europe, as a solace to their
cold and humid clime; and was first made known to the southern nations
in the writings of Arnoldus de Villa Nova, and his pupil, Raymond Lully
of Majorca, who declares this admirable essence of wine to be an
emanation of the Divinity, an element newly revealed to man, but hid
from antiquity, because the human race were then too young to need this
beverage, destined to revive the energies of modern decrepitude. He
further imagined that the discovery of this _aqua vitæ_, as it was
called, indicated the approaching consummation of all things--the end of
this world. However much he erred as to the value of this remarkable
essence, he truly predicted its vast influence upon humanity, since to
both civilized and savage nations it has realized greater ills than were
threatened in the fabled box of Pandora.

I shall consider in this place the first three of these subjects,
reserving for the article STILL an account of the construction and use
of that apparatus.

Whiskey, from the Irish word Usquebaugh, is the British name of the
spirituous liquor manufactured by our distillers, and corresponds to the
_Eau de vie_ of the French, and the _Branntwein_ of the Germans. It is
generated by that intestine change which grape juice and other
glutino-saccharine liquids spontaneously undergo when exposed to the
atmosphere at common temperatures; the theory of which will be expounded
under the article FERMENTATION. The production of whiskey depends upon
the simple fact, that when any vinous fluid is boiled, the alcohol being
very volatile, evaporates first, and may thereby be separated from the
aqueous vegetable infusion in which it took its birth. Sugar is the only
substance which can be transformed into alcohol. Whatsoever fruits,
seeds, or roots afford juices or extracts capable of conversion into
vinous liquor, either contain sugar ready formed, or starch susceptible
of acquiring the saccharine state by proper treatment. In common
language, the intoxicating liquor obtained from the sweet juices of
fruits is called wine; and that from the infusions of farinaceous seeds,
beer; though there is no real difference between them in chemical
constitution. A similar beverage, though probably less palatable, is
procurable from the juices and infusions of many roots, by the process
of fermentation. Wine, cyder, beer, and fermented wash of every kind,
when distilled, yields an identical intoxicating spirit, which differs
in these different cases merely in flavour, in consequence of the
presence of a minute quantity of volatile oils of different odours.

I. The juices of sweet fruits contain a glutinous ingredient which acts
as a ferment in causing their spontaneous change into a vinous
condition; but the infusions of seeds, even in their germinated or
malted state, require the addition of a glutinous substance called
yeast, to excite the best fermentation. In the fabrication of wine or
beer for drinking, the fermentative action should be arrested before all
the fruity saccharum is decomposed; nor should it on any account be
suffered to pass into the acetous stage; whereas for making distillery
wash, that action should be promoted as long as the proportion of
alcohol is increased, because the formation of a little acetic acid is
not injurious to the quality of the distilled spirit, but rather
improves its flavour by the addition of acetic ether, while all the
undecomposed sugar is lost. Distillers operate upon the saccharine
matter from corn of various kinds in two methods; in the first they draw
off a pure watery extract from the grain, and subject this species of
wort to fermentation; in the second they ferment and distil the infused
mass of grains. The former is the practice of the distillers in the
United Kingdom, and is preferable on many accounts; the latter, which is
adopted in Germany, Holland, and the north of Europe, is less
economical, more uncertain in the product, and affords a cruder spirit,
in consequence of the fetid volatile oil evolved from the husks in the
still. The substances employed by the distillers may be distributed into
the following classes:--

1. Saccharine juices. At the head of these stands cane-juice, which
fresh from the mill contains from 12 to 16 per cent. of raw sugar, and
like the must of the grape enters into the vinous fermentation without
the addition of yeast, affording the species of spirit called Rum, which
is possessed of a peculiar aroma derived from an essential oil in the
cane. An inferior sort of rum is fabricated from molasses, mixed with
the skimmings and washings of the sugar pans. When molasses or treacle
is diluted with twenty times its weight of warm water, and when the
mixture has cooled to 78° F., if one twelfth of its weight of yeast be
added, fermentation will speedily ensue, and an ardent spirit will be
generated, which when distilled has none of the aroma of rum; proving
this to reside in the immediate juice or substance of the cane, and to
be dissipated at the high temperature employed in the production of
molasses. Though the cane juice will spontaneously undergo the vinous
fermentation, it does so more slowly and irregularly than the routine of
business requires, and therefore is quickened by the addition of the
lees of a preceding distillation. So sensible are the rum distillers of
the advantage of such a plan, that they soak woollen cloths in the yeast
of the fermenting vats, in order to preserve a ferment from one sugar
season to another. In Jamaica and some other of our colonies, 50 gallons
of spent wash or lees are mixed with 6 gallons of molasses, 36 gallons
of sugar-pan skimmings (a substance rich in aroma), and 8 gallons of
water; in which mixture there is about one twelfth part of solid
saccharum. Those who attend more to the quality than the quantity of
their rum, will use a smaller proportion of the spent wash, which is
always empyreumatic, and imparts more or less of its odour to the spirit
distilled from it. The fermentation is seldom complete in less than 9
days, and most commonly it requires from 12 to 15; the period being
dependent upon the capacity of the fermenting tun, and the quality of
its contents. The liquid now becomes clear, the froth having fallen to
the bottom, and few bubbles of gas are extricated from it, while its
specific gravity is reduced from 1·050 down to 0·992. The sooner it is
subjected to distillation after this period the better, to prevent the
loss of alcohol by the supervention of the acetous stage of
fermentation, an accident very liable to happen in the sugar colonies.
The crude spirit obtained from the large single still at the first
operation, is rectified in a smaller still. About 114 gallons of rum,
proof strength, specific gravity 0·920, are obtained from 1200 gallons
of wash. Now these 1200 gallons weigh 12,600 libs., and contain nearly
one eighth of their weight of sugar = 1575 libs.; which should yield
nearly its own weight of proof spirit, whose bulk is = 1575/0·92 = 1712
pound measures = 171·2 gallons; whereas only 114 are obtained; proving
the processes to be conducted in a manner far from economical, even with
every reasonable allowance.

Mr Edwards gives the following estimate: “The total amount of sweets
from an estate in Jamaica which makes 200 hogsheads of sugar, is 16,666
gallons. The wash set at the rate of 12 per cent. sweets, should return
34,720 gallons of low wines, which should give 14,412 gallons of rum, or
131 puncheons of 110 gallons each.”

By my own experiments on the quantity of proof spirit obtainable from
molasses by fermentation (afterwards to be detailed), one gallon of
sweets should yield one gallon of spirit; and hence the above 16,666
gallons should have afforded the same bulk of rum. But here we are left
somewhat in the dark, by not knowing the specific gravity of the rum
spoken of by Mr. Edwards. The only light let in upon us is when he
mentions rum oil-proof, that is, a spirit in which olive oil will sink;
indicating a density nearly the same with our actual excise proof, for
olive oil at 60° F. has the specific gravity 0·919. When a solution of
sugar of the proper strength is mixed with wine lees, and fermented, it
affords a spirit by distillation not of the rum, but of the brandy
flavour.

The sweet juices of palm trees and cocoa nuts, as also of the maple, and
ash, birch, &c., when treated like cane juice, afford vinous liquors
from which ardent spirits, under various names, are obtained; as
_arrack_, &c.; the quantity being about 50 pounds of alcohol of 0·825
for every 100 pounds of solid saccharine extract present. Honey
similarly treated affords the metheglin so much prized by our ancestors.
Good whey, freed from curd by boiling, will yield 4 per cent. of spirit
of wine, when fermented with the addition of a little yeast.

2. The juices of apples, pears, currants, and such fruits, afford by
fermentation quantities of alcohol proportional to the sugar they
contain. But the quality of the spirit is much better when it is
distilled from vinous liquids of a certain age, than from recently
fermented must. Cherries are employed in Germany, and other parts of the
Continent, for making a high-flavoured spirit called _Kirsch-wasser_, or
cherry water. The fully ripe fruit is crushed by a roller press, or an
edge-stone mill, along with the kernels; the pulp is fermented in a
mass, the liquid part is then drawn off, and distilled. More or less
prussic acid enters from the kernels into this spirit, which renders it
very injurious, as a liquor, to many constitutions. I was once nearly
poisoned by swallowing a wine glass of it in the valley of Chamouni. The
ripened red fruit of the mountain ash constitutes a good material for
vinous fermentation. The juice being mixed with some water and a little
yeast, affords when well fermented, according to Hermstaedt, 12 pounds,
or 1-1/2 gallons, of alcohol from 2 bushels of the ripe berries.

3. Many roots contain sugar, particularly beet, from which no less than
7 per cent. of it may be extracted by judicious means. Hermstaedt
recommends to mash the steam boiled clean roots, and add to the paste
two-thirds of its weight of boiling water, and a thirtieth of its weight
of ground malt, mixing the materials well, and then leaving them three
hours in a covered vessel. The mixture must now be passed through a wire
sieve, with meshes of one-third of an inch square each; the residuum is
washed with a little cold water, and, when the temperature has fallen to
77° F., the proper quantity of yeast must be added, and the fermentation
suffered to proceed in a covered tun. In 5 or 6 days it will be
complete, and will afford by distillation, from 100 pounds of beet root,
about 10 or 12 pounds of proof spirits. Carrots and parsnips, when
similarly treated, yield a considerable quantity of alcohol.

II. _Ardent spirits or whiskey from fecula or starchy materials._

I have already pointed out, in the article BEER, how the starch is
transformed into a saccharine condition, by malting and mashing; and how
a fermentable wort may be obtained from starchy meal. By like operations
may all vegetable substances, which consist chiefly of starch, become
materials for a whiskey distillery. To this class belong all the
farinaceous grains, potatos, and the pods of shell fruits, as beans,
vetches, horse-chesnuts, acorns, &c.

1. _Whiskey from corn._ All those species of corn which are employed in
breweries answer for distilleries; as wheat, rye, barley, and oats; as
well as buckwheat, and maize or Indian corn. The product of spirits
which these different grains afford, depends upon the proportion of
starch they contain, including the small quantity of uncrystallizable
sugar present in them. Hermstaedt, who has made exact experiments upon
the subject, reckons a quart (Prussian or British) spirits, containing
30 per cent. of the absolute alcohol of Richter, for 2 pounds of starch.
Hence 100 pounds of starch should yield 35 pounds of alcohol; or 4·375
gallons imperial, equal to 7·8 gallons of spirits, excise proof.

100 pounds of the following grains afford in spirits of specific gravity
0·9427, containing 45 per cent. of absolute alcohol (= 9/11 of British
proof,) the following quantities:--

Wheat, 40 to 45 pounds of spirits; rye, 36 to 42; barley, 40; oats, 36;
buckwheat, 40; maize, 40. The mean of the whole may be taken at 40
pounds, equal to 4-1/4 gallons imperial, of 0·9427 specific gravity =
3·47 gallons, at excise proof. The chief difference in these several
kinds of corn consists in their different bulks under the same weight; a
matter of considerable importance; for since a bushel of oats weighs
little more than the half of a bushel of wheat, the former becomes for
some purposes less convenient in use than the latter, though it affords
a good spirit.

Barley and rye are the species of grain most commonly employed in the
European distilleries for making whiskey. Barley is mostly taken either
partly or altogether in the malted state; while the other corns are not
malted, but merely mixed with a certain proportion of barley malt to
favour the saccharine fermentation in the mashing. It is deemed
preferable to use a mixture of several sorts of grain, instead of a
single one; for example, wheat with barley and oats; or barley with rye
and wheat; for the husks of the oats diffused through the wheat flour
and rye meal keep it open or porous when mashed, and thus favour the
abstraction of the wort; while the gluten of the wheat tends to convert
the starch of the barley and oats into sugar. When the whole of the
grain, however, is malted, a much more limpid wort is obtained than from
a mixture of malt with raw grain; hence the pure malt is preferable for
the ale and porter brewer, while the mixture affords a larger product,
at the same cost of materials, to the distiller. When barley is the only
grain employed, from one-third to one-sixth of malt is usually mixed
with it; but when wheat and rye are also taken, the addition of from
one-eighth to one-sixteenth of barley malt is sufficient. Oats are
peculiarly proper to be mixed with wheat, to keep the meal open in the
mashing.

The following are the proportions used by some experienced Scotch
distillers.

  250 bolls, containing 6 bushels each, being used for a mashing,
      consist of,
  ---
   25 bolls of oats, weighing 284 lbs. per boll, or 47-1/3 lbs. per
      bushel;
   42          malt           240                   40
   25          rye            320                   53-1/3
  158          barley         320                   53-1/3
  ---                                               ------
  250                                         mean  48-1/2
  ---                                               ------

From each boll, weighing 291 lbs., 14 imperial gallons of proof whiskey
are obtained on an average; equivalent to 11·2 gallons at 25 over proof.

The malting for the distilleries is to be conducted on the same
principles as for the breweries, but the malt ought to be lightly
kiln-dried, and that preferably at a steam heat, instead of a fire,
which is apt to give an empyreumatic smell to the grain that passes into
the spirits. For such persons, indeed, as relish the smell of burned
turf, called peat-reek in Scotland, the malt should be dried by a turf
fire, whereby the whiskey will acquire that peculiar odour.

But this smell, which was originally prized as a criterion of whiskey
made from pure malt, moderately fermented and distilled with peculiar
care, has of late years lost its value, since the artifice of
impregnating bad raw grain whiskey with peat-smoke has been extensively
practised.

Dr. Kolle, in his treatise on making spirits, describes a malting kiln
with a copper plate heated with steam, 18 feet long, and 12 feet broad,
on which a quantity of malt being spread thin, is changed every 3 or 4
hours, so that in 24 hours he turns out upwards of 28 cwt. of an
excellent and well-kilned article. The malt of the distiller should be
as pale as possible, because with the deepening of the colour an
empyreumatic principle is generated.

When Indian corn is the subject of distillation, it must be malted in
the same way as described in the article BEER. According to Hermstaedt,
its flour may be advantageously mixed with the crushed malt in the mash
tun. But its more complete dissolution may be accomplished by Siemen’s
mode of operating upon potatos, presently to be described.

1. _Mashing._ Barley and raw grain are ground to meal by millstones, but
malt is merely crushed between rollers. If only one-tenth or one-eighth
of malt be used with nine-tenths or seven-eighths of barley, some husks
of oats are added, to render the mash mixture more drainable.

When 40 bushels of barley and 20 of malt form one mashing, from 600 to
700 gallons of water, heated to 150° F., are mixed with these 60 bushels
in the mash tun, and carefully incorporated by much manual labour with
wooden oars, or in great concerns by the mechanical apparatus used in
the breweries. This agitation must be continued for 2 or 3 hours, with
the admission from time to time of about 400 additional gallons of
water, at a temperature of 190°, to counteract the cooling of the
materials. But since the discovery of _diastase_, as the best heat for
saccharifying starch is shewn to be not higher than 160° F., it would be
far better to mash in a tun, partially, at least, steam encased, whereby
we could preserve the temperature at the appropriate degree for
generating the greatest quantity of sugar.

If the wort be examined every half-hour of the mashing period, it will
be found to become progressively sweeter to the taste, thinner in
appearance, but denser in reality.

The wort must be drawn off from the grains whenever it has attained its
maximum density, which seldom exceeds 150 lbs. per barrel; that is, (360
+ 150)/360 = 1·42, or 42 per cent. As the corn of the distiller of raw
grain has not the same porosity as the brewer’s, the wort cannot be
drawn off from the bottom of the tun, but through a series of holes at
the level of the liquor, bored in a pipe stuck in at the corner of the
vessel. About one-third only of the water of infusion can thus be drawn
off from the pasty mass. More water is therefore poured on at the
temperature of 190°, well mixed by agitation for half an hour, then
quietly infused for an hour and a half, and finally drawn off as before.
Fully 400 gallons of water are used upon this occasion, and nearly as
much liquor may be drawn off. Lastly, to extract from the grains every
thing soluble, about 700 gallons of boiling hot water are turned in upon
them, thoroughly incorporated, then left quietly to infuse, and drawn
off as above. This weak wort is commonly reserved for the first liquor
of the next mashing operation upon a fresh quantity of meal and malt.

The English distiller is bound by law to make his mixed worts to be let
down into the fermenting tun of a specific gravity not less than 1·050,
nor more than 1·090; the Scotch and Irish distillers not less than
1·030, nor more than 1·080; which numbers are called, gravity 50, 90,
30, and 80, respectively.

With the proportion of malt, raw grain, and water, above prescribed, the
infusion first drawn off may have a strength = 20 per cent. = spec.
grav. 1·082, or 73 lbs. per barrel; the second of 50 lbs. per barrel, or
14 per cent.; and the two together would have a strength of 61·2 lbs.
per barrel = 17 per cent., or spec. grav. 1·070. From experiments
carefully made upon a considerable scale, it appears that no more than
four-fifths of the soluble saccharo-starchy matter of the worts is
decomposed in the best regulated fermentations of the distiller from raw
grain. For every 2 lbs. so decomposed, 1 lb. of alcohol, spec. grav.
0·825 is generated; and as every gallon of spirits of the spec. grav.
0·909 contains 4·6 lbs. of such alcohol, it will take twice 4·6 or 9·2
lbs. of saccharine matter to produce the said gallon. To these 9·2 lbs.,
truly transmuted in the process, we must add one-fifth, or 1·84 lbs.,
which will raise to 11·04 the amount of solid matter employed in
producing a gallon of the above spirits.

Some distillers mash a fourth time; and always use the feeble wort so
obtained in mashing fresh grain.

2. As the imperfect saccharine infusion obtained from raw grain is much
more acescent than the rich sugary solution got from malt in the
breweries, the distiller must use every precaution to cool his worts as
quietly as possible, and to keep them clear from any acetous taint. The
different schemes of cooling worts are considered under BEER and
REFRIGERATION. As the worts cool, a quantity of starchy matter is
precipitated, but it is all carefully swept along into the fermenting
tun, and undoubtedly contributes to increase the production of alcohol.
During the winter and temperate months, when the distilleries are most
actively at work, the temperature at which the worts are set is usually
about 70° F. When much farinaceous deposit is present, the heat may be
only 65°, because, in this case, a slow fermentation seems to favour the
conversion of that starch into sugar. In some German distilleries a
little chalk is mixed with the worts, to check acidity.

3. _The fermentation._

The yeast added to the worts as a ferment, ought to be the best top barm
of the London porter breweries. About 1 gallon of it is requisite for
every 2 bushels of meal and malt worked up in the mashing process; and
of this quantity only a certain proportion is introduced at the
beginning; the remainder being added by degrees, on the second and third
day.

Should the fermentation flag, a little more may be added on the fourth
or fifth day, and the contents of the tun may be roused by an agitator.
About 8 or 9 gallons may be introduced four days in succession to the
quantity of worts extracted from 60 bushels of the farinaceous
materials; or the third day’s dose may be intermitted, and joined to the
fourth on the subsequent day.

Great diversity, and no little caprice prevail among distillers in
respect of the periods of administering the yeast; but they should be
governed very much by the appearance of the fermentation. This process
continues from nine to twelve or even fourteen days, according to
circumstances; the tuns being left quite open during the first five
days, but being covered moderately close afterwards to favour the full
impregnation of the liquor with carbonic acid, as a fermenting agent. In
consequence of the great attenuation of the wort by the generation of so
much alcohol, no good body of yeast continues to float on the surface,
and what is formed is beat down into the liquor on purpose to promote
the fermentation. The temperature of the wash gradually increases till
towards the end of the fourth day, when it attains its maximum height of
about 25° above the pitch of 55° or 60° at which it may have been set.
The time of the greatest elevation of temperature, as well as its
amount, depends conjointly upon the quality of the yeast, the nature of
the saccharo-starchy matter, and the state of the weather. It is highly
probable that the electrical condition of the atmosphere exercises a
considerable influence upon fermentation. We know the power of a
thunderstorm to sour vinous fluids. An experimental inquiry into the
relation between electricity and fermentation, could not fail to prove
both curious and profitable.

The diminution of the density of the wort is carefully watched by the
distiller, as the true criterion of the success of his process. This
_attenuation_, as he calls it, is owing partly to the decomposition of
the sugar, which communicated its gravity to the solution, and partly to
the introduction of the lighter alcoholic particles. Were all the
saccharo-starchy matter resolved into gaseous compounds, the wort would
become water; but since a part of it remains undecomposed, and a portion
of alcohol is produced at the expense of the decomposed part, the degree
of attenuation becomes a somewhat complicated problem in a theoretical
point of view; the density due to the residuary sugar being masked and
counteracted by the spirit evolved. Could the alcohol be drawn off as it
is formed, the attenuation would probably become greater, because the
alcohol checks the fermentative action, and eventually stops it, before
all the saccharum is decomposed. After the wash has taken its highest
degree of temperature, not much more spirit is found to be generated;
were this therefore removed by proper means, the remaining vegetable
matter would undoubtedly yield a further product of alcohol.

In the attenuation of raw-grain wash, the specific gravity seldom
arrives at 1·000; but most commonly stops short at 1·002 or 1·004. When
the vinous fermentation comes to an end, the acetous is apt to commence,
and to convert a portion of the alcohol into vinegar; a result which is
easily ascertained by the increasing specific gravity, sour smell, and
acidulous reaction of the wash upon litmus paper, which remains after
the paper is heated, showing that the red colour is not caused by
carbonic acid.

Fermentation proceeds with more uniformity and success in the large tuns
of the distiller, than in the experimental apparatus of the chemist;
because the body of heat generated in the former case maintains the
action. But I have succeeded in obviating this inconvenience in
operating upon 80 or 90 gallons, by keeping up the temperature, when it
begins to flag, by transmitting hot water through a recurved pipe
plunged into the tun.

We have already mentioned that one gallon of spirits, one in ten
over-proof, is upon the average generated from 11·04 libs. of starch
sugar; hence we conclude that one pound water-measure of spirits at
proof (= 1/10 imperial gallon) is produced from one pound of the
saccharum.

_Malt whiskey._--The treatment and produce of malt distilleries are in
some respects different from those of raw grain. Having been
professionally employed by the proprietors of both, I am prepared to
state the peculiarities of the latter, by an example. 500 bushels of
ground malt are first mashed with 9000 gallons of water, heated to the
temperature of 160° F.: 6000 gallons of worts are drawn off into the
coolers, and let down into the fermenting tun at 68°. From 3 to 4 per
cent. of a mixture of London porter yeast with quick Scotch barm, are
added, and well stirred through the mass. At the end of two or three
days, in general, the fermentation is finished. On the residuary grains
of the malt, from 4500 to 5000 gallons of water at 180° are run, which
after proper mashing as before, are drawn off; then 4500 more are poured
on, the drainage of which is added to the second. Both of these
together, constituting 9000 gallons, are heated next day, and employed
for the mashing of 500 bushels of fresh malt. During the fermentation,
the wash which was set at the spec. grav. 1·065, comes down to water =
1·000.

The wash is distilled in two stills, appropriated to it, of about 800
gallons capacity each, provided with a rotatory chain apparatus for
preventing the lees from adhering to the bottom of the still. Into about
800 gallons of wash 8 lbs. of soap are put. The liquor obtained at this
first distillation is called low-wines. These low-wines are redistilled
in the spirit stills; the first and last portions of liquid being more
or less blue or milky in colour, and rank in flavour, are run into a
separate receiver called the _faints-back_; while the middle portion,
constituting in a well-managed distillery, from three-fourths to
four-fifths of the whole, are received into the spirit-back. The faints
are mixed with a large quantity of water, and redistilled, in order to
free them from the fetid oil derived from the husks of the grain. The
interception of this noxious oil may be best effected by a
self-regulating bath, between the capital of the still and the
refrigeratory, as will be explained in treating of STILLS. The capitals
of the common Scotch stills are made from 15 to 20 feet high, in order
to prevent the chance of the wash boiling over into the worm; and they
are, towards the beginning of the process, struck from time to time with
a rod, and by the sound emitted it is known whether they be empty,
partially filled, or in danger of an overflow; in which case the fire is
damped, by a spout near the furnace door, connected by a leather pipe
with an elevated reservoir of water. When very pure spirits are wished
for, a third or even a fourth distillation is had recourse to; there
being a quantity of water mixed each time with the spirit in the still,
to prevent its acquiring a harsh alcoholic flavour.

According to some experienced distillers from raw grain, the mashing
temperature of the first liquor should not exceed 140° F.; whereas with
malt it may be safely and beneficially 165° or 170°. When rye is used
instead of malt, 90 bushels of it are mixed with 190 bushels of raw
grain, constituting 280 bushels in whole, for the mashing of which 5200
gallons of water are required. An hour and a half more time is necessary
for settling the mashing of the above mixture, than of grain alone. Gin
is made in this way.

The distiller of malt whiskey calculates on obtaining two gallons of
proof spirits from one bushel of malt, in average years. The highest
yield is 20 gallons per quarter of 8 bushels; and the lowest is 16, when
the malt and fermentation are indifferent. The best temperature to set
the fermenting tuns with malt wash is about 70° or 72° F.

When malt is 5_s._ the bushel, 6 bushels at 30_s._ will yield 12 gallons
of proof spirits. These cost therefore 2_s._ 6_d._ per gallon for the
malt; to which must be added 3_d._ per bushel for the amount of malt
duty not returned, or 1-1/2_d._ on the gallon; this added to the Scotch
duty of 3_s._ 4_d._ the gallon, makes the price altogether 5_s._
11-1/2_d._; besides the expenses in fuel, yeast, labour, and rent, which
may be estimated at 8-1/2_d._ per gallon. But 3_d._ may be deducted for
what is paid by the dairymen for the spent wash and grains. The total
cost, therefore, exclusive of use of capital, is 6_s._ 5_d._ per gallon
in Scotland.

The following is the work of a Scotch distillery, where good malt
whiskey was made.

One bushel of the malt weighed 35 libs., or the boll, = 6 bushels, 210
libs. In mashing each boll of malt, 110 gallons of water were run on it
at 160° F. As soon as the fermenting tun of 3000 gallons capacity was
charged with the wash at from 64° to 74° F., 2 gallons per cent. of barm
were added. When the wash had become attenuated from 1·060 to 1·040,
another gallon of barm was introduced.

The temperature of the fermenting wash sometimes rises to 96°, which is,
however, an extreme case, and not desirable. When the bubbles of
carbonic acid mount in rapid succession, it is reckoned an excellent
sign. If the tun be small, and stand in a cool apartment, it should be
started at a higher temperature than in the reverse predicament. Should
the fermentation be suffered to flag, it is in general a hopeless task
to restore vigorous action. Some try the addition of _bubs_, that is of
some wort brought into a state of rapid fermentation in a tub, by a
large proportion of yeast, but seldom with much success. Indeed the law
prohibits the addition of any wort to the tun at a later period than 24
hours after it is set; so that if bubs are used afterwards, the
distiller is apt to incur a penalty.

The maximum quantity of proof spirits obtained on the great scale at any
time from raw grain mixed with from one-fourth to one-eighth of malt,
seems to be 22 gallons per quarter.

By the British laws a distiller is not allowed to brew and distil at the
same time but he must work alternately, one week, for instance, at
fermentation, and next week at distillation.

In fermenting solutions of sugar mixed with good yeast, the attenuation
has been carried down to 0·984, and even 0·982, that is, in the language
of the excise, 16 and 18 degrees below water, from 1·060, the density at
which it was originally set in the tun. This was excellent work done on
the scale of a great distillery nearly 30 years ago, when distillation
from sugar was encouraged, in consequence of bad corn harvests.

In an experiment which I made in 1831 for the information of a committee
of the House of Commons, on the use of molasses in the breweries and
distilleries, I dissolved 1 cwt. of raw sugar in water; so as to form
74-1/2 gallons, inclusive of 2 gallons of yeast. The specific gravity of
the mixture was 1·0593 on the 31st of March. By the 6th of April, that
is in 6 days, the gravity had sunk to 0·992, or 8 degrees under water,
which was reckoned a good attenuation, considering the circumstances and
the small quantity operated upon. By distillation it afforded at the
rate of 14·875 gallons of proof spirits for 100 gallons of the wash.

When the distillers first worked from sugar, they only obtained upon an
average from 1 cwt. 10·09 gallons imp. of proof spirit; but they
afterwards got no less than 11·92 imp. gallons.

The following experiment, which I made upon the fermentation of West
India molasses into spirits, for the information of the said committee,
may prove not uninteresting to my readers. 150 libs. were dissolved in
water and mixed with 2 gallons of yeast, weighing exactly 20 libs. The
wash measured 70 gallons, and had a spec. gravity of 1·0647 at 60° F. In
two days the gravity had fallen to 1·0055; in three days to 1·0022; and
in five days to 1·001. The temperature was kept up at from 80° to 90°
F., during the two last days, by means of a steam pipe, to favour the
fermentation. The product of spirits was 11 gallons, and 35/100 of a
gallon. Now 150 libs. of the above molasses were found to contain of
solid matter, chiefly uncrystallizable, 112 libs. And as 112 libs. of
sugar are estimated by the revenue laws to afford by fermentation 11-1/2
gallons imp. of proof spirit, the result of that experiment upon
molasses must be considered satisfactory, bearing in mind that the
saccharine substance in molasses has been not only partially decomposed
by heat, but is mixed with some of the glutinous or extractive matter of
the cane.

Since the alteration of the excise laws relative to distillation in 1825
and 1826, when permission was given to set the wort at lower gravities,
the quantity of spirits produced from 1 quarter of corn has been much
increased, even up to fully 20 gallons; and the proportion of malt has
been much diminished. The latter was soon reduced from three-sevenths
malt, and four-sevenths barley, or two-fifths malt and three-fifths
barley, to one-fifth of malt, and now to one-tenth or even
one-sixteenth.

A discussion having lately taken place in Ireland between certain
persons connected with the distilleries and the officers of the excise,
whether, and to what extent, raw grain worts would pass spontaneously
into the vinous fermentation, the Board in London requested me to
superintend a series of researches in a laboratory fitted up at their
office, to settle this important point. I shall content myself here with
giving the result of one experiment, out of several, which seems to me
quite decisive. Three bushels of mixed grains were taken, consisting of
two of barley, one half of oats, and one half of malt, which, being
coarsely ground by a hand-mill, were mashed in a new tun with 24 gallons
of water at 155°. The mash liquor drawn off amounted to 18 gallons, at
the density of 1·0465; and temperature of 82° F. Being set in a new tun,
it began to ferment in the course of 12 hours, and in 4 days it was
attenuated down to gravity 1·012. This yielded, upon distillation in low
wines, 3·22 gallons, and by rectification, in spirits, 3·05; while the
quantity equivalent to the attenuation by the tables was 3·31, being an
excellent accordance in such circumstances.

The inquisitorial _regime_ imposed by law upon our distilleries, might
lead a stranger to imagine that our legislators were desirous of
repressing by every species of annoyance the fabrication of the fiery
liquid which infuriates and demoralizes the lower population of these
islands. But alas! credit can be given them for no such moral or
philanthropic motive. The necessity of the exchequer to raise a great
revenue, created by the wasteful expenditure of the state, on the one
hand, and the efforts of fraudulent ingenuity on the other, to evade the
payment of the high duties imposed, are the true origin of that
_regime_. Examinations in distilleries are constantly made by the
officers of excise. There is a survey at 6 o’clock in the morning, when
the officers take their accounts and gauges, and make calculations which
occupy several hours. At 10 o’clock they again survey, going over the
whole premises, where they continue a considerable time, frequently till
the succeeding officer comes on duty; at 2 in the afternoon another
survey takes place, but not by the same people; at 6 in the evening the
survey is repeated; at 10 there comes another survey by an officer who
had not been engaged in any of the previous surveys of that day. He is
not relieved till 6 o’clock next morning. In addition to these regular
inspections, the distilleries are subject to frequent and uncertain
visits of the surveyor and general surveyor. “We are never,” says Mr.
Smith, the eminent distiller of Whitechapel, “out of their hands.”[24]

  [24] Report of Committee on Molasses, 2198.

Before the fermented wort goes into the still, a calculation is made of
the quantity of wash drawn from the wash back, and which is first pumped
into what is called the wash charger. If the quantity in the wash
charger exceeds the quantity in the wash back, the distiller is charged
upon the higher quantity; if it contains less, he must pay according to
the wash back, as being the larger quantity. When the quantity of wash
is all transferred to the charger, the discharge cock of the wash
charger is unlocked, and the wash is allowed to be drawn off from the
charger into the still, the charging and discharging cock of the still
being locked by the officer. There can be no transfer of wash but
through the pumps, which are locked also. The first distillation from
the wash is worked into the low-wine receiver, which is also a locked-up
vessel; then of those low wines, the strength and quantity are
ascertained by the excise. The account of them affords a comparison with
the quantity which the contents of the wash-back had been estimated to
produce; they are then pumped from the low-wine receiver, through pumps
previously locked into the low-wine charger, which is also a locked-up
vessel; from the locked-up charger, after the officer has done his duty
regarding it, they are allowed to be drawn off into the low-wine still,
which is a distillation of the second extraction; then that low wine
still works into another locked-up cask, called the spirit receiver, for
the receiving of raw spirits; when that distillation is finished, the
officer, attending again on regular notice for that purpose, takes the
quantity and strength of the spirits therein, and upon the quantity so
ascertained he charges the duty. In distilling low wines, one portion of
them goes into the spirit receiver, and a portion into what is called
the faint receiver, which is another locked-up vessel. These faints are
in the next distillation united with the low wines, from the succeeding
wash-back on their second distillation, and are worked together; the
united produce of these goes partly into the spirit cask, and partly
back again into the faint cask. The operation is thus continued till all
the backs in the house are emptied.[25]

  [25] Thomas Smith, Esq., of Whitechapel Road, in Report of Molasses
  Committee, Part II. p. 149.

There is a kind of ardent spirits manufactured in Holland, vulgarly
called Dutch gin, Hollands, and sometimes _geneva_, from _genievre_, the
French for juniper, a plant with the essential oil of whose berries it
is flavoured. One cwt. of ground malt mixed with two cwt. of rye meal
are mashed for two hours, with about 450 gallons of water at the
temperature of 160° F. The mash drawn off is reduced with cold water
till the liquid part has the density of 45 libs. per barrel, = specific
gravity 1·047; and is then put altogether into the fermenting back at
the temperature of 80° F. One or two gallons of yeast are added. The
fermentation soon becomes so vigorous as to raise the heat to 90° and
upwards, but it is not pushed far, being generally over in two days,
when the gravity of the wash, still indicates 12 pounds of saccharum per
barrel. By this moderate attenuation, like that practised by the
contraband distillers of the Highlands of Scotland, it is supposed that
the fetid oil of the husks is not evolved, or at least in very small
quantity. The grains are put into the alembic along with the liquid
wash, and distilled into low wines, which are rectified twice over, some
juniper berries and hops being added at the last distillation. But the
junipers are sometimes bruised and put into the mash. The produce of
worts so imperfectly fermented, is probably little more than one half of
what the British distiller draws from the same quantity of grain. But
the cheapness of labour and of grain, as well as the superior flavour of
the Schiedam spirits, enables the Dutch distiller to carry on his
business with a respectable profit. In opposition to the above facts,
Dubrunfaut says that about one third more spirits is obtained in Holland
from grain than in France, because a very calcareous spring water is
employed in the mashing operation. Were this account well founded, all
that the distillers of other countries would have to do would be merely
to introduce a portion of chalk into their mash tuns, in order to be on
a par with the Dutch. But the statement is altogether a mistake.

In the vine countries, the inferior wines or those damaged by keeping,
as also a fermented mash of the pressed grapes, mixed with water, are
distilled to form the _eau de vie de Cognac_ of the French, called
Brandy in this country. It contains less essential oil, and that of a
more agreeable flavour, than corn spirits. See BRANDY.

Berzelius says that there are distillers who are guilty of putting a
little arsenious acid into the still; that the spirits contain pretty
frequently traces of arsenic, which may be detected by adding to them a
little muriatic acid, then evaporating off the alcohol, and passing a
current of sulphuretted hydrogen gas through the residuary liquid, which
will give it the characteristic orpiment yellow tinge, arsenic being
present. Copper, which is sometimes introduced into distilled grain, or
even malt spirits, in consequence of the soap employed in the process of
distillation, may be detected best by the brown precipitate which it
occasions with ferroprussiate of potash. No arsenic is ever used in this
country.

When damaged grain has been mashed in making whiskey, a peculiar oily
substance makes its appearance in it. On approaching the nostrils to
such whiskey slightly heated, this volatile matter irritates the
pituitary membrane and the eyes very powerfully. These spirits have
exactly the smell of an alcoholic solution of cyanogene; they intoxicate
more powerfully than pure alcohol of equal strength, and produce even
temporary frenzy, with subsequent sickness and disordered functions.
This volatile body is not cyanogene, though it be so like it, for it
forms no such combinations as cyanogene does. It may be extracted from
diluted alcohol by agitating it with an unctuous oil, and then
distilling the oil along with water. At the end of 3 or 4 months, this
volatile matter disappears in a great measure, even when the spirits
impregnated with it are inclosed in well-corked bottles; obviously from
its undergoing a spontaneous decomposition. It may be preserved much
longer in the state of a watery solution.

When acetic ether is added to well purified or clean spirits, such as
the distillers call silent whiskey, it gives it somewhat of the flavour
of brandy. For this purpose, also, the spirits are rectified from
bruised prunes, or the lees of the cognac distilleries, whereby they
acquire additional flavour. The astringent taste of old brandy is
imitated by the introduction of a little catechu into the British
spirits. Burned sugar is employed as a colouring in these imitations.

IV. _Of making whiskey from potatos._--This root in certain localities
where it abounds at a moderate price, is an excellent material for
fermenting into alcohol. When sound, it possesses from 20 to 25 per
cent. of solid substance, of which starch constitutes at least
three-fourths; hence 100 pounds contain from 16 to 22 pounds of starch
susceptible of being saccharified. In the expressed juice there is a
small quantity of tartaric acid.

[Illustration: 361]

Previously to mashing, potatos must be first well washed in a horizontal
cylindrical cage revolving partially in a trough of water, as will be
described in treating of the manufacture of sugar from beet root. They
must be then boiled in a close vessel with steam, provided with a
perforated bottom a few inches above the real one. The top has an
opening with a cover fitted tightly to it; through that the potatos are
introduced; and immediately above the false bottom there is a similar
aperture through which the boiled potatos are taken out. The steam-pipe
enters at the top, runs down the side a little way; and terminates in a
widened mouth. The large lids are secured by cross bars, the small hole
by folds of linen. In the lower valve there are two small holes closed
with pins, for inserting a wire to feel whether the potatos be
sufficiently boiled. If so, the steam is immediately stopped off, the
lower lid is removed, and the potatos pulled out with a hook into a tub.
They must be immediately made into a homogeneous paste before they get
cold. _Fig._ 361. represents, in plan, or horizontal section, the
apparatus used in France for this purpose. A B are two cylinders covered
with wire cloth, but open at the ends; C C and D D are two pieces of
wood fixed on the two axes, in the form of two cones, with the adjoining
surfaces truncated; upon which, as also upon iron rings E F, of the same
diameter, made fast to the axes, the wire cylinder rests. Of the two
wheels G, H, the smaller has 18, the greater has 21 teeth. The diameter
of each cylinder is 14 inches, the length 18. Above and between the two
cylinders, there is a hopper for the reception of the boiled potatos.
This machine triturates 1200 pounds of potatos per hour. Their paste
must be forthwith mashed with some ground wheat or barley, and a
proportion of malt; then be set a fermenting.

[Illustration: 362]

As in the above mode of trituration, the potatos are apt to cool to such
a degree as to obstruct their ready admixture with water, it is better
to make them into a paste in the vessel in which they are steamed. The
apparatus contrived by Siemens fully answers this end. It consists
essentially of a tub A, represented in _fig._ 362. in section. It is
cylindrical, and made of planks from 3 to 4 inches thick, joined firmly
and steam-tight; the upper and under ends being well secured with iron
hoops. The lower part is about 2 inches more in diameter than the upper.
About a foot from the bottom, in a circular groove, a cast iron
partition W or disc full of holes is made fast, which serves the purpose
of a scarce, the apertures being an inch asunder; above, from 1/8 to
1/10 of an inch in diameter, and below, scooped out to half an inch.
This disc is half an inch thick in the edges, and five fourths of an
inch in the middle.

Through the female screw _a_ in the top of the cylinder, there passes
the screwed rod _b_, one and a half inches thick, provided at top with a
strong cross bar C C, for turning it round. The under end of this rod
has a square piece terminating in a short screw, upon which a wrought
iron cross is secured by means of a screw nut, so as to stand at right
angles to the rod. This cross is composed of two distinct arms; of which
one of them is mounted on the upper side with little knives an inch and
a half long; the other, upon the under side, with a wire brush, that may
be made to rub against the perforated cast iron disc. On the side of the
cylinder at E, _fig._ 362., there is a narrow aperture provided with a
bung secured by a cross bar, and near the bottom at H there is another
like it. Both openings serve for taking out the residuary matter.
Through the opening E, the above two arms are introduced; and secured to
the square of the rod by the screw nut. In the top there is an opening,
D, for putting in the potatos which may be shut in the same way. From
the lid there likewise issues a lateral tube F, which terminates in a
tubful of water, for condensing the waste steam. G is the tube connected
with the steam boiler, for conducting the steam into the space under the
iron disc W.

With this apparatus the potatos are prepared as follows: when the screw
rod is so fixed that the cross touches the disc, the cylinder is to be
filled with washed potatos to within one foot of the top, leaving them
some space to expand. The orifice D is to be then closed, and the steam
admitted. When the potatos are boiled enough, two labourers lay hold of
the lever handles C C, of the screw rod _b_, and turn it round with the
effect of screwing up the spiked cross, and of triturating the potatos;
an operation which may be still more effectually done by screwing it
down again. The potato paste is now let off by the plug hole H, into the
tub L, where it is mixed with about 30 per cent. of boiling water, and
one thousandth part of potash, made caustic with quicklime, in order to
dissolve the albuminous matter coagulated by the heat, and give complete
fluidity to the mass. The alkali also neutralises the tartaric acid
present. The mashed matter must now be mixed with the crushed malt
diffused through 40 or 50 pounds of cold water for every 100 pounds of
potatos, which lowers the temperature to 167°. The wort must be then
diligently stirred during two hours; mixed with 40 or 50 pounds of cold
water for 100 pounds of potatos, and when reduced to the temperature of
77° put into the fermenting tun along with the proper quantity (3 or 4
per cent.) of yeast. As potatos readily pass into the acetous
fermentation, the admixture of the malt, the mashing, and the cooling
should be rapidly performed, while the utmost cleanliness must be
observed.

The fermentation is brisk, probably from the agency of the albumen, and
furnishes a good head of barm, which answers well for the bakers; 100
pounds of potatos yield from 18 to 20 pounds measure of spirits, nine
elevenths of our excise proof; or about 16 pounds measure of proof, =
about 1-2/3 gallons.

It has been observed that after the month of December potatos begin to
yield a smaller product of fermented spirits; and when they have once
sprouted or germinated, they afford very little indeed. From the
difficulty of keeping and transporting potatos, distillation from them,
even though our laws now permit it, can never become general till some
plan be adopted for overcoming these disadvantages. A scheme of this
kind, however, has been successfully practised in Vienna, which consists
in subjecting the washed potatos to strong pressure in a perforated
chest by a hydraulic or screw press, whereby they lose about three
fourths of their weight, and may then be readily dried into a white
flour, that may be kept for several years without injury, and
transported to considerable distances with comparative ease. This flour,
mixed with a moderate quantity of ground malt, and saccharified by
mashing with water, at the temperature of 167° F., becomes capable of
affording a sweet wort convertible by fermentation either into beer or
whiskey.

Horse-chestnuts, according to Hermstaedt, are an eligible material for
producing alcohol, as 128 pounds of them afford 100 pounds of meal;
which 100 pounds yield, by proper treatment, 34 pounds of spirits,
containing 36 per cent. of absolute alcohol, by Richter’s tables. Barley
to the extent of 10 pounds per 100 should be ground up with them, after
they have been boiled in a steam apparatus, not only for the purpose of
softening them, but freeing them from their bitter astringent matter.
Acorns are productive of alcohol by similar treatment.

The best means hitherto discovered for depriving bad whiskey of its
nauseous smell and taste, is to pass it through well-burned and coarsely
pulverised charcoal, distributed as follows in a series of cylindrical
casks. Each vessel must have a double bottom, the false one being
perforated with conical holes, and placed a few inches above the true.
Upon this perforated board a layer of chopped clean straw one inch thick
is laid; and over the straw, a stratum of small river gravel, the size
of large peas. This is to be covered with a pretty thick stratum of the
charcoal, previously freed from dirt and dust by washing; upon which a
piece of close canvass is to be spread, and pressed down by a thin bed
of river sand. The cylinder or cask should be filled with these
successive layers to within two inches of its top, and it is then to be
closed air-tight. Immediately below the head, a round orifice is pierced
in the side, for receiving an overflow tube, which is either screwed
rectangularly to another elbow pipe, or is bent (when of block tin) so
as to enter tight into an orifice beneath the false bottom of the second
cylinder or cask. In this way, the series may be continued to any
desired number of vessels; the last discharging the purified spirit into
the store-back. The foul spirit must be made to flow into the bottom
space of the first cylinder down through a pipe in communication with a
charging-back placed upon such an elevated level as to give sufficient
pressure to force the spirits up through the series of filters; the
supply-pipe being provided with a regulating stop-cock. The spirit may
be filtered _downwards_ through sand and cloth in its final passage to
the receiver. It has been found, with very crude spirits, that eight
successive cylinders were required to deprive them entirely of the rank
flavour.

In the year 1831, 23,000,000 gallons of spirits were made in the United
Kingdom, equivalent to the consumption of 1,500,000 quarters of grain,
and for that year and the four preceding years, there were imported
annually 2,000,000 of quarters of foreign barley.

  In 1832, 20,778,521 gallons paid excise duty.
     1834, 23,397,806.
     1836, 27,137,000; of which 14,000,000 were Irish.

We may add to the last quantity, 3 millions of gallons at least on the
score of smuggling, in licensed and illicit distilleries; making 30
millions to be the frightful amount of whiskey consumed by the British
people, independent of other intoxicating liquors.


DOCIMACY, from the Greek Δοκιμαζω, I prove; (_Docimasie_, Fr.;
_Probierkunst_, Germ.;) is the art by which the nature and proportions
of an ore are determined. This analytical examination was originally
conducted in the dry way, the metal being extracted from its
mineralizers, by means of heat and certain fluxes. But this method was
eventually found to be insufficient and even fallacious, especially when
volatile metals were in question, or when the fluxes could absorb them.
The latter circumstance became a very serious evil, whenever the object
was to appreciate an ore that was to be worked at great expense.
Bergmann first demonstrated, in an elaborate dissertation, that the
humid analysis was much to be preferred; and since his time the dry way
has been consecrated chiefly to the direction of metallurgic operations,
or, at least, it has been employed merely in concert with the humid, in
trials upon the small scale.

After discovering an ore of some valuable metal, it is essential to
ascertain if its quantity and state of combination will justify an
adventurer in working the mine, and smelting its products. The metal is
rarely found in a condition approaching to purity; it is often
disseminated in a mineralizing _gangue_ far more bulky than itself; and
more frequently still it is combined with simple non-metallic
substances, such as sulphur, carbon, chlorine, oxygen, and acids, more
or less difficult to get rid of. In these compound states its
distinctive characters are so altered, that it is not an easy task
either to recognize its nature, or to decide if it can be smelted with
advantage. The assayer, without neglecting any of the external
characters of the ore, seeks to penetrate, so to speak, into its
interior; he triturates it to an impalpable powder, and then subjects it
to the decomposing action of powerful chemical reagents; sometimes with
the aid of alkalies or salts appropriate to its nature, he employs the
dry way by fire alone; at others, he calls in the solvent power of acids
with a digesting heat; happy, if after a series of labours, long,
varied, and intricate, he shall finally succeed in separating a notable
proportion of one or more metals either in a pure state, or in a form of
combination such, that from the amount of this known compound, he can
infer, with precision, the quantity of fine metal, and thereby the
probable value of the mine. The blow-pipe, skilfully applied, affords
ready indications of the nature of the metallic constituents, and is
therefore usually the preliminary test. The separation of the several
constituents of the ore can be effected, however, only by a chemist, who
joins to the most extensive knowledge of the habitudes of mineral
substances, much experience, sagacity, and precision, in the conduct of
analytical operations. Under the individual metals, as also in the
articles METALLURGY, MINES, and ORES, I have endeavoured to present such
a copious and correct detail of docimastic processes, as will serve to
guide the intelligent student through this most mysterious labyrinth of
nature and art.


DORNOCK, is a species of figured linen of stout fabric, which derives
its name from a town in Scotland, where it was first manufactured for
table-cloths. It is the most simple in pattern of all the varieties of
the diaper or damask style, and therefore the goods are usually of
coarse quality for common household wear. It receives the figure by
reversing the flushing of the warp and woof at certain intervals, so as
to form squares, or oblong rectangles upon the cloth. The most simple of
these is a succession of alternate squares, forming an imitation of a
checker board or mosaic work. The coarsest kinds are generally woven as
tweels of three leaves, where every thread floats over two, and is
intersected by the third in succession. Some of the finer are tweels of
four or five leaves, but few of more; for the six and seven leaf tweels
are seldom or never used, and the eight leaf tweel is confined almost
exclusively to damask. See TEXTILE FABRIC.


DRAGON’S BLOOD; (_Sang dracon_, Fr.; _Drachenblut_, Germ.) is a resinous
substance, which comes to us sometimes in small balls of the size of a
pigeon’s egg, sometimes in rods, like the finger, and sometimes in
irregular cakes. Its colour, in lump, is dark brown red; in powder,
bright red; friable; of a shining fracture, sp. grav. 1·196. It contains
a little benzoic acid, is insoluble in water, but dissolves readily in
alcohol, ether, and oils. It is brought from the East Indies, Africa,
South America, as the produce of several trees, the _Dracæna Draco_, the
_Pterocarpus santalinus_, the _Pterocarpus Draco_, and the _Calamus
Rotang_.

Dragon’s blood is used chiefly for tingeing spirit and turpentine
varnishes, for preparing gold lacquer, for tooth tinctures and powders,
for staining marble, &c. According to Herbenger, it consists of 9·07
parts of red resin, 2 of fat oil, 3 of benzoic acid, 1·6 of oxalate, and
3·7 of phosphate of lime.


DRUGGET, is a coarse, but rather slight, woollen fabric, used for
covering carpets, and as an article of clothing by females of the poorer
classes. It is now-a-days nearly superseded by coarse cotton goods.

[Illustration: 363]


DRYING HOUSE. An apartment fitted up in a peculiar manner for drying
calicoes, and other textile fabrics. Mr. Southworth, of Sharples, a
Lancashire bleacher, obtained a patent, in 1823, for the following
ingenious arrangement, which has been since generally adopted, with
certain modifications, in most of our extensive bleaching and printing
works. _Fig._ 363. is a section of the drying-house, where _a_ is a
furnace and boiler for the purpose of generating steam; it is furnished
with a safety valve in the tube _b_, at top, and from this tube the
steam main _c_ passes down to the floor of the basement story. From this
main, a series of steam-pipes, as _d d_, extend over the surface of the
floor, and from them heat is intended to be diffused for the purpose of
warming the drying-house.

Along the middle of the building a strong beam of timber _e e_, extends,
and is supported by cast-iron pillars; from this beam, to bearings on
the side walls, a series of rails are carried in a cross direction, over
which rails the wet cloth is to be hung in folds, and the steam or
evaporation emitted in drying is allowed to escape through apertures or
ventilators in the roof.

The mode in which the cloth is delivered on to the rails, on either side
of the beam, will be best understood by reference to the delivering
carriage, which is shown, with its rollers partly in section.

The wet cloth is first to be coiled upon a roller, and then placed in
the carriage, as at _f_, with its pivots bearing upon inclined planes.
The carriage is to be placed at the commencement of the rails, running
upon the middle beam, and also upon the side-bearings or railways
extending along the side walls of the building, parallel to and upon a
level with the same beam. It is made to travel by means of an endless
band passing over two riggers, _g_ and _h_, in _fig._ 363., and over
pulleys and a band-wheel attached to the carriage, as will be explained.
The rigger _g_, which moves this endless band, is actuated by bevel
geer, seen at _i_, which is put in motion by a pinion at the end of a
revolving shaft leading from a steam engine.

In the same _fig._, _k k_ is the endless band passing over a pulley
under the band-wheel, and over the pulley _n_, by which it will be
perceived that the traversing of the band, as described, would cause
these pulleys and wheels to revolve. On the axle of the band-wheel _m_,
there is a drum against which the roll of wet cloth _f_ presses, and as
this drum revolves, the roll of wet cloth is, by its friction, made to
turn in a contrary direction, and to deliver off the cloth on to the
periphery of the drum, whence it passes over a roller and descends to
the tails. Upon the end of the axle of the band-wheel _m_, there is a
pinion which takes into the teeth of the large wheel, and upon the axle
of this large wheel there is a pinion that actuates the intermediate
wheel, which turns another toothed wheel. This last-mentioned toothed
wheel takes into cogs upon the side railway, and hence, as the train of
wheels moves round, the carriage to which the wheels are attached is
slowly impelled forward.

As soon as the wheels begin to move, and the carriage to advance, the
wet cloth begins to uncoil, and to pass down over the first roller; a
small roller attached to the carriage, as it passes over the rails in
succession, holds the cloth against each rail for a short space of time,
and prevents it from slipping, by which means the cloth descends in
folds or loops between the rails, and is thereby made to hang in a
series of folds or loops, as shown in the figure.

It will be perceived that as the pivots of the cloth roller _f_ bear
upon inclined planes, the roller will continually slide down as the
cloth diminishes in bulk, keeping in contact with the drum, and
delivering the cloth from the roller on to the several rails, as
described.

In order to stop the carriage in any part of its course, or to adjust
any of the folds of the cloth, a man is usually placed upon the platform
travelling with the carriage, over which he has perfect command. This
apparatus may be also employed for taking the cloth when dried off the
rails; in which case the carriage must be made to travel backwards, and
by first guiding the end of the cloth on to the roller _f_, and then
putting the wheels in a retrograde motion, the cloth will be
progressively coiled upon the roller _f_, in a similar way to that by
which it was uncoiled.


DUCTILITY, (_Streckbarkeit_, Germ.) is the property of being drawn out
in length without breaking, possessed in a pre-eminent degree by gold
and silver, as also by many other metals, by glass in the liquid state,
and by many semifluid resinous and gummy substances. The spider and the
silk-worm exhibit the finest natural exercise of ductility upon the
peculiar viscid secretions from which they spin their threads. When a
body can be readily extended in all directions under the hammer, it is
said to be malleable, and when into fillets under the rolling press, it
is said to be laminable.

_Table of the ductility and malleability of Metals._

  +-------------------+---------------+--------------+--------------+
  |  Metals ductile   |Brittle metals | Metals in the|Metals in the |
  | and malleable in  |in alphabetical|order of their|order of their|
  |alphabetical order.|     order.    | wire-drawing |  laminable   |
  |                   |               | ductility.   |  ductility.  |
  +-------------------+---------------+--------------+--------------+
  |    Cadmium.       |  Antimony.    |  Gold.       |  Gold.       |
  |    Copper.        |  Arsenic.     |  Silver.     |  Silver.     |
  |    Gold.          |  Bismuth.     |  Platinum.   |  Copper.     |
  |    Iron.          |  Cerium. ?    |  Iron.       |  Tin.        |
  |    Iridium.       |  Chromium.    |  Copper.     |  Platinum.   |
  |    Lead.          |  Cobalt.      |  Zinc.       |  Lead.       |
  |    Magnesium.     |  Columbium. ? |  Tin.        |  Zinc.       |
  |    Mercury.       |  Iridium.     |  Lead.       |  Iron.       |
  |    Nickel.        |  Manganese.   |  Nickel.     |  Nickel.     |
  |    Osmium.        |  Molybdenum.  |  Palladium. ?|  Palladium. ?|
  |    Palladium.     |  Osmium.      |  Cadmium. ?  |  Cadmium. ?  |
  |    Platinum.      |  Rhodium.     |              |              |
  |    Potassium.     |  Tellurium.   |              |              |
  |    Silver.        |  Titanium.    |              |              |
  |    Sodium.        |  Tungsten.    |              |              |
  |    Tin.           |  Uranium.     |              |              |
  |    Zinc.          |               |              |              |
  +-------------------+---------------+--------------+--------------+

There appears to be therefore a real difference between ductility and
malleability; for the metals which draw into the finest wire are not
those which afford the thinnest leaves under the hammer or in the
rolling press. Of this fact iron affords a good illustration. Among the
metals permanent in the air, 17 are ductile and 16 are brittle. But the
most ductile cannot be wire-drawn or laminated to any considerable
extent without being annealed from time to time during the progress of
the extension, or rather, the sliding of the particles alongside of each
other, so as to loosen their lateral cohesion.


DUNGING, in calico-printing, is the application of a bath of cowdung,
diffused through hot water, to cotton goods in a particular stage of the
manufacture. Dunging and scouring are commonly alternated, and are two
of the most important steps in the process. The operation of dunging has
for its objects:--

1. To determine the entire combination of the aluminous sub-salts with
the stuffs, by separating almost all the acetic acid which was not
volatilized in the stove-drying of the mordant.

2. To dissolve and carry off from the cloth a portion of the thickening
matters.

3. To separate from the cloth the part of the mordant that is
uncombined, and merely mixed mechanically with the gum or starch.

4. To prevent, by the peculiar action of the dung, the uncombined
mordant, as well as the acetic acid with which the bath is apt to get
loaded, from affecting the blank parts of the cloth, or being injurious
to the mordant.

The aluminous base or mordant on the cloth, more or less neutralized by
the dunging, is next subjected to the dash-wheel or fulling mill, where
by the stream of water the remainder of the thickening and other
impurities are washed away.

No very exact analysis has been made of cowdung. Morin’s, which is the
most recent and elaborate, is as follows:--

  Water                                    70·00
  Vegetable fibre                          24·08
  Green resin and fat acids                 1·52
  Undecomposed biliary matter               0·60
  Peculiar extractive matter (_bubuline_)   1·60
  Albumen                                   0·40
  Biliary resin                             1·80

According to M. Kœchlin’s practical knowledge on the great scale, it
consists of a moist fibrous vegetable substance, which is animalized,
and forms about one-tenth of its weight; 2. of albumen; 3. of animal
mucus; 4. of a substance similar to bile; 5. of muriate of soda, muriate
and acetate of ammonia, phosphate of lime and other salts; 6. of benzoin
or musk.

Probably the hot water in which the calico-printer diffuses the dung,
exerts a powerful solvent action, and in proportion as the uncombined
mordant floats in the bath it is precipitated by the albumen, the animal
mucus, and the ammoniacal salts; but there is reason to think that the
fibrous matter in part animalized or covered with animal matter, plays
here the principal part; for the great affinity of this substance for
the aluminous salts is well known.

All practical men are aware that the affinity of cotton for alumina is
increased by its combination with oil or animal substances, to such a
degree as to take it from the dung bath; which would not be possible
without this combination. It would therefore appear that the principal
function of dunging is to hinder the uncombined mordant, diffused in the
dung bath, from attaching itself to the unmordanted portion of the
cloth, as already observed; for if we merely wished to abstract the
thickening stuffs, or to complete by the removal of acetic acid the
combination of the aluminous base with the goods, dung would not be
required, for hot water would suffice. In fact, we may observe, that in
such cases the first pieces passed through the boiler are fit for
dyeing; but when a certain number have been passed through, the mordant
now dissolved in the water is attracted to the white portions of the
cloth, while the free acid impoverishes the mordanted parts, so that
they cannot afford good dyes, and the blank spaces are tarnished.

The cow dung may be in some measure replaced by bran, but not with
perfect success. The former both answers the purpose better and is
cheaper. The bran is only preferred for the most delicate yellows, for
cochineal pinks and lilacs, to which the dung may sometimes impart a
greenish cast. It is to be presumed that the action of the bran in this
process has much analogy with that of the dung, and that the ligneous
fibre is the most active constituent; with which the gluten and mucilage
co-operate, no doubt, in seizing the aluminous salts.

It seems to be ascertained that the mordant applied to the cloth does
not combine entirely with it during the drying; that this combination is
more or less perfect according to the strength of the mordants, and the
circumstances of the drying; that the operation of dunging, or passing
through hot water, completes the combination of the cloth with the
aluminous base now insoluble in water; that this base may still contain
a very minute quantity of acetic acid or sulphate of alumina; that a
long ebullition in water impoverishes the mordant but a little; and that
even then the liquid does not contain any perceptible quantity of
acetate or subsulphate of alumina.

The manner of immersing the goods, or passing them through the dung
bath, is an important circumstance. They should be properly extended and
free from folds, which is secured by a series of cylinders.

The cistern is from 10 to 12 feet long, 4-1/2 feet wide, and 6 or 8 feet
deep. The piece passes alternately over the upper rollers and under
rollers near the bottom. There are two main squeezing rollers at one
end, which draw the cloth through between them. Whenever the goods come
out of the bath they are put into the dash-wheel. The immersion should
take place as fast as possible, for the moment the hot water penetrates
the mordanted cloth, the acetic acid quits it; and, therefore, if the
immersion was made slowly or one ply after another, the acid as well as
the uncombined mordant become free, would spread their influence, and
would have time to dissolve the aluminous subsalts now combined with the
cloth; whence inequalities and impoverishment of the colours would
ensue.

It is difficult to determine the number of pieces which may be passed
through a given quantity of dung and water. This depends upon the state
of the mordants, whether they are strong or acid, and on the quantity of
the surface covered with the figures. The number varies usually from 20
to 60 pieces, for from 240 to 300 gallons of water and 6 gallons of
dung. The time of the immersion varies with the concentration of the
mordants, and the nature of their thickening. The temperature must be
regulated by the same circumstances; for starch or flour paste a much
warmer bath is needed than for gum. The heat varies usually from 130° to
212° F. When the printing is heavy and the thickening is starch or
flour, the goods are usually twice dunged, with two washings between the
two dungs. A strong acid mordant is more difficult to dung and to wash
than a neutral mordant, especially when it is to receive the madder dye.
Sometimes a little chalk is added to the bath, when the goods have been
padded in an acid mordant. Too much dung is injurious to weak mordants,
as well as to pinks. It has also been remarked that a mordant when
neutralized does not produce as brilliant tints, especially yellows. The
latter are obtained of a finer shade when, instead of dunging, they are
exposed for an hour in a stream of water, provided its temperature is
not too low. In winter they are passed through a slightly chalky water,
then washed at the wheel, and dyed in quercitron or weld.

A very able and learned memoir upon this subject, by M. Penot, Professor
of Chemistry, appeared in the Bulletin of the Society of Mulhausen, in
October, 1834, with an ingenious commentary upon it, under the title of
a Report by M. Camille Kœchlin, in March, 1835.

Experience has proved that dunging is one of the most important steps in
the process of calico printing, and that if it be not well performed the
dyeing is good for nothing. Before we can assign its peculiar function
to the dung in this case, we must know its composition. Fresh cow’s dung
is commonly neutral when tested by litmus paper; but sometimes it is
slightly alkaline, owing, probably, to some peculiarity in the food of
the animal.

The total constituents of 100 parts of cow dung are as follows: Water,
69·58; bitter matter, 0·74; sweet substance, 0·93; chlorophylle, 0·28;
albumine, 0·63; muriate of soda, 0·08; sulphate of potash, 0·05;
sulphate of lime, 0·25; carbonate of lime, 0·24; phosphate of lime,
0·46; carbonate of iron, 0·09; woody fibre, 26·39; silica, 0·14; loss,
0·14.

In dunging calicoes the excess of uncombined mordant is in part
attracted by the soluble matters of the cow’s dung, and forms an
insoluble precipitate, which has no affinity for the cloth, especially
in presence of the insoluble part of the dung, which strongly attracts
alumina. The most important part which that insoluble matter plays, is
to seize the excess of the mordants, in proportion as they are dissolved
by the water of the bath, and thus to render their reaction upon the
cloth impossible. It is only in the deposit, therefore, that the matters
carried off from the cloth by the dung are to be found.

M. Camille Kœchlin ascribes the action of cow dung chiefly to its
albuminous constituent, combining with the alumina and iron, of the
acetates of these bases dissolved by the hot water of the bath. The
acids consequently set free, soon become evident by the test of litmus
paper, after a few pieces are passed through, and require to be got rid
of either by a fresh bath or by adding chalk to the old one. The dung
thus serves also to fix the bases on the cloth, when used in moderation.
It exercises likewise a disoxidating power on the iron mordant, and
restores it to a state more fit to combine with colouring matter.


DYEING, (_Teinture_, Fr.; _Färberei_, Germ.) is the art of impregnating
wool, silk, cotton, linen, hair, and skins, with colours not removable
by washing, or the ordinary usage to which these fibrous bodies are
exposed when worked up into articles of furniture or raiment. I shall
here consider the general principles of the art, referring for the
particular dyes, and peculiar treatment of the stuffs to be dyed, to the
different tinctorial substances in their alphabetical places; such as
cochineal, indigo, madder, &c.

Dyeing is altogether a chemical process, and requires for its due
explanation and practice an acquaintance with the properties of the
elementary bodies, and the laws which regulate their combinations. It is
true that many operations of this, as of other chemical arts, have been
practised from the most antient times, long before any just views were
entertained of the nature of the changes that took place. Mankind,
equally in the rudest and most refined state, have always sought to
gratify the love of distinction by staining their dress sometimes even
their skin, with gaudy colours. Moses speaks of raiment dyed blue, and
purple, and scarlet, and of sheep-skins dyed red; circumstances which
indicate no small degree of tinctorial skill. He enjoins purple stuffs
for the works of the tabernacle and the vestments of the high priest.

In the article CALICO PRINTING, I have shown from Pliny that the antient
Egyptians cultivated that art with some degree of scientific precision,
since they knew the use of mordants, or those substances which, though
they may impart no colour themselves, yet enable white robes (_candida
vela_) to absorb colouring drugs (_colorem sorbendibus medicamentis_).
Tyre, however, was the nation of antiquity which made dyeing its chief
occupation and the staple of its commerce. There is little doubt that
purple, the sacred symbol of royal and sacerdotal dignity, was a colour
discovered in that city, and that it contributed to its opulence and
grandeur. Homer marks no less the value than the antiquity of this dye,
by describing his heroes as arrayed in purple robes. Purple habits are
mentioned among the presents made to Gideon by the Israelites from the
spoils of the kings of Midian.

The juice employed for communicating this dye was obtained from two
different kinds of shell-fish, described by Pliny under the names of
_purpura_ and _buccinum_; and was extracted from a small vessel, or sac,
in their throats, to the amount of only one drop from each animal. A
darker and inferior colour was also procured by crushing the whole
substance of the buccinum. A certain quantity of the juice collected
from a vast number of shells being treated with sea-salt, was allowed to
ripen for three days; after which it was diluted with five times its
bulk of water, kept at a moderate heat for six days more, occasionally
skimmed to separate the animal membranes, and when thus clarified was
applied directly as a dye to white wool, previously prepared for this
purpose by the action of lime-water, or of a species of lichen called
fucus. Two operations were requisite to communicate the finest Tyrian
purple; the first consisted in plunging the wool into the juice of the
purpura; the second, into that of the buccinum. Fifty drachms of wool
required one hundred of the former liquor, and two hundred of the
latter. Sometimes a preliminary tint was given with coccus, the kermes
of the present day, and the cloth received merely a finish from the
precious animal juice. The colours, though probably not nearly so
brilliant as those producible by our cochineal, seem to have been very
durable, for Plutarch says, in his _Life of Alexander_, (chap. 36.),
that the Greeks found in the treasury of the king of Persia a large
quantity of purple cloth, which was as beautiful as at first, though it
was 190 years old.[26]

  [26] ‘Among other things, there was purple of Hermione (?) to the
  amount of five thousand talents.’ (Plutarch’s Lives, translated by
  Langhorne, Wrangham’s edition, vol. v. p. 240.) Horace celebrates the
  Laconian dye in the following lines:--

    Nec Laconicas mihi
    Trahunt honestæ purpuras clientæ.

    (Carm., lib. ii., Ode 18.)


The difficulty of collecting the purple juice, and the tedious
complication of the dyeing process, made the purple wool of Tyre so
expensive at Rome that in the time of Augustus a pound of it cost nearly
30_l._ of our money.[27] Notwithstanding this enormous price, such was
the wealth accumulated in that capital, that many of its leading
citizens decorated themselves in purple attire, till the emperors
arrogated to themselves the privilege of wearing purple, and prohibited
its use to every other person. This prohibition operated so much to
discourage this curious art as eventually to occasion its extinction,
first in the western and then in the eastern empire, where, however, it
existed in certain imperial manufactories till the eleventh century.

  [27] Pliny says that a pound of the double-dipped Tyrian purple was
  sold in Rome for a hundred crowns.

Dyeing was little cultivated in antient Greece; the people of Athens
wore generally woollen dresses of the natural colour. But the Romans
must have bestowed some pains upon this art. In the games of the circus
parties were distinguished by colours. Four of these are described by
Pliny, the green, the orange, the grey, and the white. The following
ingredients were used by their dyers. A crude native alum mixed with
copperas, copperas itself, blue vitriol, alkanet, lichen rocellus, or
archil, broom, madder, woad, nut-galls, the seeds of pomegranate, and of
an Egyptian acacia.

Gage, Cole, Plumier, Reaumur, and Duhamel have severally made researches
concerning the colouring juices of shell-fish caught on various shores
of the ocean, and have succeeded in forming a purple dye, but they found
it much inferior to that furnished by other means. The juice of the
buccinum is at first white; it becomes by exposure to air of a yellowish
green bordering on blue; it afterwards reddens, and finally changes to a
deep purple of considerable vivacity. These circumstances coincide with
the minute description of the manner of catching the purple-dye
shell-fish which we possess in the work of an eye-witness, Eudocia
Macrembolitissa, daughter of the Emperor Constantine VIII., who lived in
the eleventh century.

The moderns have obtained from the New World several dye-drugs unknown
to the antients; such as cochineal, quercitron, Brazil wood, logwood,
annatto; and they have discovered the art of using indigo as a dye,
which the Romans knew only as a pigment. But the vast superiority of our
dyes over those of former times must be ascribed principally to the
employment of pure alum and solution of tin as mordants, either alone or
mixed with other bases; substances which give to our common dye-stuffs
remarkable depth, durability, and lustre. Another improvement in dyeing
of more recent date is the application to textile substances of metallic
compounds, such as Prussian blue, chrome yellow, manganese brown, &c.

Indigo, the innoxious and beautiful product of an interesting tribe of
tropical plants, which is adapted to form the most useful and
substantial of all dyes, was actually denounced as a dangerous drug, and
forbidden to be used, by our parliament in the reign of Queen Elizabeth.
An act was passed authorizing searchers to burn both it and logwood in
every dye-house where they could be found. This act remained in full
force till the time of Charles II.; that is, for a great part of a
century. A foreigner might have supposed that the legislators of England
entertained such an affection for their native woad, with which their
naked sires used to dye their skins in the old times, that they would
allow no outlandish drug to come in competition with it. A most
instructive book might be written illustrative of the evils inflicted
upon arts, manufactures, and commerce, in consequence of the ignorance
of the legislature.[28]

  [28] Author, in Penny Cyclopedia.

Colours are not, properly speaking, material; they are impressions which
we receive from the rays of light reflected, in a decomposed state, by
the surfaces of bodies. It is well known that a white sunbeam consists
of an indeterminate number of differently coloured rays, which being
separated by the refractive force of a glass prism, form the solar
spectrum, an image distinguishable into seven sorts of rays; the red,
orange, yellow, green, blue, indigo, and violet. Hence, when an opaque
body appears coloured, for example, red, we say that it reflects the red
rays only, or in greatest abundance, mixed with more or less of the
white beam, which has escaped decomposition. According to this manner of
viewing the colouring principle, the art of dyeing consists in fixing
upon stuffs, by means of corpuscular attraction, substances which act
upon light in a different manner from the surfaces of the stuffs
themselves. The dyer ought, therefore, to be familiar with two
principles of optics; the first relative to the mixture of colours, and
the second to their simultaneous contrast.

Whenever the different coloured rays, which have been separated by the
prism, are totally reunited, they reproduce white light. It is evident,
that in this composition of light, if some rays were left out, or if the
coloured rays be not in a certain proportion, we should not have white
light, but light of a certain colour. For example; if we separate the
red rays from the light decomposed by a prism, the remaining coloured
rays will form by their combination a peculiar bluish green. If we
separate in like manner the orange rays, the remaining coloured rays
will form by their combination a blue colour. If we separate from the
decomposed prismatic light the rays of greenish yellow, the remaining
coloured rays will form a violet. And if we separate the rays of yellow
bordering on orange, the remaining coloured rays will form by their
union an indigo colour.

Thus we see that every coloured light has such a relation with another
coloured light that, by uniting the first with the second, we reproduce
white light; a relation which we express by saying that the one is the
complement of the other. In this sense, red is the complementary colour
of bluish green; orange, of blue; greenish yellow, of violet; and orange
yellow, of indigo. If we mix the yellow ray with the red, we produce
orange; the blue ray with the yellow, we produce green; and the blue
with the red, we produce violet or indigo, according as there is more or
less red relatively to the blue. But these tints are distinguishable
from the orange, green, indigo, and violet of the solar spectrum,
because when viewed through the prism they are reduced to their
elementary component colours.

If the dyer tries to realize the preceding results by the mixture of
dyes, he will succeed only with a certain number of them. Thus, with red
and yellow he can make orange; with blue and yellow, green; with blue
and red, indigo or violet. These facts, the results of practice, have
led him to conclude that there are only three primitive colours; the
red, yellow, and blue. If he attempts to make a white, by applying red,
yellow, and blue dyes in certain quantities to a white stuff, in
imitation of the philosopher’s experiment on the synthesis of the
sunbeam, far from succeeding, he will deviate still further from his
purpose, since the stuff will by these dyes become so dark coloured, as
to appear black.

This fact must not, however, lead us to suppose that in every case where
red, yellow, and blue are applied to white cloth, black is produced. In
reality, when a little ultramarine, cobalt blue, Prussian blue, or
indigo, is applied to goods with the view of giving them the best
possible white, if only a certain proportion be used, the goods will
appear whiter after this addition than before it. What happens in this
case? The violet blue forms, with the brown yellow of the goods, a
mixture tending to white, or less coloured than the yellow of the goods
and the blue together were. For the same reason, a mixture of prussian
blue and cochineal pink has been of late years used in the whitening or
the azuring of silks, in preference to a pure blue; for on examining
closely the colour of the silk to be neutralized, it was found by the
relations of the complementary colours, that the violet was more
suitable than the indigo blue formerly used. The dyer should know, that
when he applies several different colouring matters to stuffs, as yellow
and blue, for example, if they appear green, it is because the eye
cannot distinguish the points which reflect the yellow from those which
reflect the blue; and that, consequently, it is only where the
distinction is not possible, that a mixture or combination appears. When
we examine certain gray substances, such as hairs, feathers, &c., with
the microscope, we see that the gray colour results from black points,
disseminated over a colourless or slightly coloured surface. In
reference to compound colours, this instrument might be used with
advantage by the dyer.

The dyer should be acquainted also with the law of the simultaneous
contrast of colours. When the eye views two colours close alongside of
each other, it sees them differing most in their optical composition,
and in the height of their tone, when the two are not equally pale or
full-bodied. They appear most different as to their optical composition,
when the complementary of the one of them is added to the colour of the
other. Thus, put a green zone alongside of an orange zone; the red
colour complementary of green, being added to the orange, will make it
appear redder; and in like manner the blue, complementary of orange,
being added to the green, will make it appear more intensely blue. In
order to appreciate these differences, let us take two green stripes and
two orange stripes, placing one of the green stripes near one of the
orange; then place the two others so that the green stripe may be at a
distance from the other green stripe, but on the same side, and the
orange at a distance from the other orange, also on the same side.

As to the contrast in the height of the tone, we may satisfy ourselves
by taking the tones No. 1. No. 2. No. 15. and No. 16. from a graduated
pallet of reds: for example, by placing No. 2. and No. 15. close
alongside, putting No. 1. at a distance from No. 2. on the same side,
and No. 16. at a distance from No. 15. on the same side,--we shall see
(if the pallet is sufficiently lowered in tone) No. 2. equal to No. 1.,
and No. 15. equal to No. 16.; whence it follows that No. 2., by the
vicinity of No. 15., will appear to have lost some of its colour; while
No. 15. will appear to have acquired colour. When black or gray figures
are printed upon coloured grounds, these figures are of the colour
complementary of the ground. Consequently, in order to judge of their
colour, we must cut out spaces in a piece of gray or white paper, so as
to allow the eye to see nothing but the figures; and if we wish to
compare figures of the same colour, applied upon grounds of different
colours, we can judge rightly of the figures only by insulating them
from the grounds.

The relations of dyeing with the principles of chemistry, constitute the
theory of the art, properly speaking; this theory has for its basis, the
knowledge--1. of the species of bodies which dyeing processes bring into
contact; 2. of the circumstances in which these species act; 3. of the
phenomena which appear during their action; and 4. of the properties of
the coloured combinations which are produced. These generalities may be
specified under the ten following heads:--

1. The preparation of the stuffs to be dyed, whether fibres, yarn, or
cloth; under the heads of ligneous matter, cotton, hemp, flax; and of
the animal matters, silk and wool.

2. The mutual action of these stuffs, and simple bodies.

3. The mutual action of these stuffs, and acids.

4. The mutual action of these stuffs, and salifiable bases, as alumina,
&c.

5. The mutual action of these stuffs, and salts.

6. The mutual action of these stuffs, and neutral compounds not saline.

7. The mutual action of these stuffs, and of one or more definite
compounds.

8. Of dyed stuffs considered in reference to the fastness of their
colour, under the influence of heat, light, water, oxygen, air, boilings
with soap, and reagents.

9. Of dyeing, considered in its connections with chemistry.

10. Of dyeing, considered in its relations with caloric, mechanics,
hydraulics, and optics.

1. The preparation of stuffs.

The operations to which stuffs are subjected before dyeing, are
intended--1. to separate from them any foreign matters; 2. to render
them more apt to unite with the colouring tinctures which the dyer
proposes to fix upon them, in order to give them a more agreeable, or
more brilliant aspect, or to lessen their tendency to assume a soiled
appearance by use, which white surfaces so readily do. The foreign
matters are either naturally inherent in the stuffs, or added to them in
the spinning, weaving, or other manipulation of manufacture. The
ligneous fibres must be freed from the coloured azotized varnish on
their surface, from a yellow colouring matter in their substance, from
some lime and iron, from chlorophylle or leaf-green, and from pectic
acid; all natural combinations. Some of these principles require to be
oxygenized, before alkaline lyes can cleanse them, as I have stated in
the article BLEACHING, which may be consulted in reference to this
subject. See also SILK and WOOL. A weak bath of soda has the property of
preparing wool for taking on a uniform dye, but it must be well rinsed
and aired before being put into the dye-vat.

2. Mutual action of stuffs, and simple bodies.

Stuffs chemically considered being composed of three or four elements,
already in a state of reciprocal saturation, have but a feeble
attraction for simple substances. We know in fact, that the latter
combine only with each other, or with binary compounds, and that in the
greater number of cases where they exert an action upon more complete
compounds, it is by disturbing the arrangement of their elements, and
not by a resulting affinity with the whole together.

3, 4. Although stuffs may in a general point of view be considered as
neutral in relation to colouring reagents, yet experience shows that
they are more disposed to combine with acid than with alkaline
compounds; and that consequently their nature seems to be more alkaline
than acid. By steeping dry wool or other stuff in a clean state in an
alkaline or acid solution of known strength, and by testing the liquor
after the stuff is taken out, we shall ascertain whether there be any
real affinity between them, by the solution being rendered more dilute
in consequence of the abstraction of alkaline or acid particles from it.
Wool and silk thus immersed, abstract a portion of both sulphuric and
muriatic acids; but cotton and flax imbibe the water, with the rejection
of a portion of the acid. The acid may be again taken from the stuffs by
washing them with a sufficient quantity of water.

5. The affinity between saline bodies and stuffs may be ascertained in
the same way as that of acids, by plunging the dry stuffs into solutions
of the salts, and determining the density of the solution before the
immersion, and after withdrawing the stuffs. Wool abstracts alum from
its solution, but it gives it all out again to boiling water. The
sulphates of protoxide of iron, of copper and zinc resemble alum in this
respect. When silk is steeped for some time in solution of protosulphate
of iron, it abstracts the oxide, gets thereby dyed, and leaves the
solution acidulous. Wool put in contact with cream of tartar decomposes
a portion of it; it absorbs the acid into its pores, and leaves a
neutral salt in the liquor. The study of the action of salts upon stuffs
is at the present day the foundation of the theory of dyeing; and some
of them are employed immediately as dye-drugs.

6. Mutual action of stuffs, and neutral compounds not saline.

Several sulphurets, such as those of arsenic, lead, copper, antimony,
tin, are susceptible of being applied to stuffs, and of dyeing them in a
more or less fast manner. Indigo, hematine, breziline, carmine, and the
peculiar colouring principles of many dyes belong to this division.

7. Mutual action of goods with one or more definite compounds, and
dye-stuffs.

I shall consider here in a theoretical point of view, the most general
results which a certain number of organic colouring matters present,
when applied upon stuffs by the dyer.

_Indigo._ This dye-drug, when tolerably good, contains half its weight
of indigotine. The cold vat is prepared commonly with water, copperas,
indigo, lime, or sometimes carbonate of soda, and is used almost
exclusively for cotton and linen; immersion in acidulated water is
occasionally had recourse to for removing a little oxide of iron which
attaches itself to the cloth dyed in this vat.

The indigo vat for wool and silk is mounted exclusively with indigo,
good potashes of commerce, madder and bran. In this vat, the immediate
principles with base of carbon and hydrogen, such as the extracts of
madder and bran, perform the disoxidizing function of the copperas in
the cold vat. The pastel vats require most skill and experience, in
consequence of their complexity. The greatest difficulty occurs in
keeping them in a good condition, because they vary progressively as the
dyeing goes on, by the abstraction of the indigotine, and the
modification of the fermentable matter employed to disoxygenate the
indigo. The alkaline matter also changes by the action of the air. By
the successive additions of indigo, alkali, &c., this vat becomes very
difficult to manage with profit and success. The great affair of the
dyer is the proper addition of lime; too much or too little being
equally injurious.

Sulphate of indigo or Saxon blue is used also to dye silk and wool. If
the wools be ill sorted it will show their differences by the
inequalities of the dye. Wool dyed in this bath put into water saturated
with sulphuretted hydrogen, becomes soon colourless, owing to the
disoxygenation of the indigo. The woollen cloth when exposed to the air
for some time, resumes its blue colour, but not so intensely as before.

The properties of hematine explain the mode of using logwood. When
stuffs are dyed in the infusion or decoction of this wood, under the
influence of a base which acts upon the hematine in the manner of an
alkali, a blue dye bordering upon violet is obtained. Such is the
process for dyeing cotton and wool a logwood blue by means of verdigris,
crystallized acetate of copper, and acetate of alumina.

When we dye a stuff yellow, red, or orange, we have always bright tints;
with blue we may have a very dark shade, but somewhat violet; the proper
black can be obtained only by using the three colours, blue, red, and
yellow, in proper proportions. Hence we can explain how the tints of
yellow, red, orange, blue, green, and violet, may be browned, by
applying to them one or two colours which along with themselves would
produce black; and also we may explain the nature of that variety of
blacks and grays which seems to be indefinite. Nutgalls and sulphate of
iron, so frequently employed for the black dye, give only a violet or
bluish gray. The pyrolignite of iron, which contains a brown
empyreumatic matter, gives to stuffs a brown tint, bordering upon
greenish yellow in the pale hues, and to chestnut brown in the dark
ones. By galling cotton and silk, and giving them a bath of pyrolignite
of iron, we may after some alternations dye them black. Galls, logwood,
and a salt of iron, produce merely a very deep violet blue; but by
boiling and exposure to air, the hematate of iron is changed, becoming
red-brown, and favours the production of black. Galls and salts of
copper dye stuffs an olive drab, logwood and salts of copper a violet
blue; hence their combination should produce a black. In using sumach as
a substitute for galls, we should take into account the proportion of
yellow matter it contains. When the best possible black is wanted upon
wool, we must give the stuff a foundation of indigo, then pass it into a
bath of logwood, sumach, and proto-sulphate of iron. The sumach may be
replaced by one third of its weight of nutgalls.

8. Of dyed stuffs considered in reference to the fastness of their
colours, when exposed to water, light, heat, air, oxygen, boiling and
reagents.

Pure water without air has no action upon any properly dyed stuff.

Heat favours the action of certain oxygenized bodies upon the
carbonaceous and hydrogenous constituents of the stuff; as is seen with
regard to chromic acid, and peroxide of manganese upon cotton goods. It
promotes the solvent action of water, and it even affects some colours.
Thus Prussian blue applied to silk, is reduced to peroxide of iron by
long boiling.

Light without contact of air affects very few dyes.

Oxygen, especially in the nascent state, is very powerful upon dyes. See
BLEACHING.

The atmosphere in a somewhat moist state affects many dyes, at an
elevated temperature. Silk dyed pink, with safflower, when heated to
400° F. becomes of a dirty white hue in the course of an hour. The
violet of logwood upon alumed wool becomes of a dull brown at the same
temperature in the same time. But both stand a heat of 300° F. Brazil
red dye, turmeric, and weld yellow dyes display the same phenomena.
These facts shew the great fixity of colours commonly deemed tender. The
stuffs become affected to a certain degree, under the same circumstances
as the dyes. The alterability even of indigo in the air is shewn in the
wearing of pale blue clothes; in the dark blue cloth there is such a
body of colour, that it resists proportionally longer; but the seams of
coats exhibit the effect very distinctly. In silk window curtains, which
have been long exposed to the air and light, the stuff is found to be
decomposed as well as the colour.

_Boiling_ was formerly prescribed in France as a test of fast dyes. It
consisted in putting a sample of the dyed goods in boiling water,
holding in solution a determinate quantity of alum, tartar, soap, and
vinegar, &c. Dufay improved that barbarous test. He considered that
fast-dyed cloth could be recognized by resisting an exposure of twelve
hours to the sunshine of summer, and to the midnight dews; or of sixteen
days in winter.

In trying the stability of dyes, we may offer the following rules:--

That every stuff should be exposed to the light and air; if it be
intended to be worn abroad, it should be exposed also to the wind and
rain; that carpets moreover should be subjected to friction and pulling,
to prove their tenacity; and that cloths to be washed should be exposed
to the action of hot water and soap.

In examining a piece of dyed cotton goods, we may proceed as follows:--

Suppose its colour to be orange-brown. We find first that it imparts no
colour to boiling water; that protochloride of tin takes out its colour;
that plunged into a solution of ferroprussiate of potash it becomes
blue; and that a piece of it being burned, leaves a residuum of peroxide
of iron; we may thence conclude that the dyeing matter is peroxide of
iron.

Suppose we have a blue stuff which may have been dyed either with indigo
or with Prussian blue, and we wish to know what it will become in use.
We inquire first into the nature of the blue. Hot water slightly
alkaline will be coloured blue by it, if it has been dyed with sulphate
of indigo; it will not be coloured if it was dyed in the indigo vat, but
it will become yellow by nitric acid. Boiling water, without becoming
coloured itself, will destroy the Prussian blue dye; an alkaline water
will convert its colour into an iron rust tint; nitric acid, which makes
the indigo dye yellow, makes that of Prussian blue green. The liquor
resulting from boiling alkaline water on the Prussian blue cloth, will
convert sulphate of iron into Prussian blue.

9. Division. Of dyeing viewed in its relation to chemistry.

The phenomena of dyeing have been ascribed to very different causes; by
some they were supposed to depend upon mechanical causes, and by others
upon the forces from which chemical effects flow. Hellot, in conformity
with the first mode of explanation, thought that the art of dyeing
consisted essentially in opening the pores in order to admit colouring
matters into them, and to fix them there by cooling, or by means of a
mordant imagined to act like a cement.

Dufay in 1737, Bergmann in 1776, Macquer in 1778, and Berthollet in
1790, had recourse to chemical affinities, to explain the fixation of
the colouring principles upon stuffs, either without an intermedium,
like indigo, walnut peels, annotto; or by the intervention of an acid, a
salifiable base, or a salt, which were called mordants. When bodies
present phenomena which we refer to an attraction uniting particles of
the same nature, whether simple or compound, to form an aggregate, or to
an affinity which unites the particles of different natures to form them
into a chemical compound, these bodies are in apparent contact. This
happens precisely in all the cases of the mutual action of bodies in an
operation of dyeing; if their particles were not in apparent contact,
there would be absolutely no change in their respective condition. When
we see stuffs and metallic oxides in apparent contact, form a mutual
union of greater or less force, we cannot therefore help referring it to
affinity. We do not know how many dyes may be fixed upon the same piece
of cloth; but in the operations of the dye-house sufficiently complex
compounds are formed, since they are always stuffs, composed of three or
four elements, which are combined with at least binary acid or basic
compounds; with simple salts compounded themselves of two immediate
principles at least binary; with double salts composed of two simple
salts; and finally with organic dye-stuffs containing three or four
elements. We may add that different species belonging to one of these
classes, and different species belonging to different classes, may unite
simultaneously with one stuff. The union of stuffs with colouring
matters appears, in general, not to take place in definite proportions;
though there are probably some exceptions.

We may conclude this head by remarking, that, besides the stuff and the
colouring matter, it is not necessary, in dyeing, to distinguish a third
body, under the name of _mordant_; for the idea of mordant does not rest
upon any definite fact; the body to which this name has been given being
essentially only one of the immediate principles of the coloured
combination which we wish to fix upon the stuff.

10. Division. Of dyeing in its relation with caloric, mechanics,
hydraulics, pneumatics, and optics.

Dyeing baths, or coppers, are heated directly by a furnace, or by means
of steam conducted in a pipe from a boiler at a certain distance from
the bath. In the first case, the vessels are almost always made of
copper; only, in special cases, for the scarlet and some delicate silk
dyes, of tin; in the second case, they are of copper, iron, or wood. A
direct fire is more economical than heating steam pipes, where there is
only one or two baths to heat, or where the labours are often suspended.
Madder and indigo vats, when heated by steam, have it either admitted
directly into the liquor, or made to circulate through pipes plunged
into it, or between the copper and an exterior iron or wood case. See
the end of this article.

Every thing else being equal, dyeing with heat presents fewer
difficulties towards obtaining an evenly colour, than dyeing in the
cold; the reason of which may be found in the following facts:--The air
adhering to the surface of stuffs, and that interposed between the
fibres of their constituent yarns, is more easily extricated in a hot
bath than a cold one, and thus allows the dye liquor to penetrate more
easily into their interior: in the second place, the currents which take
place in a hot bath, and which tend incessantly to render its contents
uniform, by renewing continually the strata of liquid in contact with
the stuff, contribute mainly to render the dyeing evenly. In cold
dyeing, it is necessary to stir up the bath from time to time; and when
goods are first put in, they must be carefully dipped, then taken out,
pressed, and wrung, several times in succession till they be uniformly
moistened.

The mechanical relations are to be found in the apparatus employed for
wincing, siring, and pressing the goods, as we have described under
CALICO PRINTING and BANDANNA. The hydraulic relations refer to the
wash-wheels and other similar apparatus, of which an account is given
under the same articles. The optical relations have been already
considered. In the sequel of this article an automatic dyeing vat will
be described.

The extracts of solutions of native dye-stuffs may be divided into two
classes, in reference to their habitudes with the oxygen of the
atmosphere; such as continue essentially unaltered in the air, and such
as suffer oxidation, and thereby precipitate a determinate colouring
matter. The dyes contained in the watery infusions of the different
vegetable and animal substances which do not belong to the second class,
are feebly attached to their solvents, and quit them readily for any
other bodies that possess an attraction for them. On this principle, a
decoction of cochineal, logwood, brazil wood, or a solution of sulphate
of indigo, by digestion with powdered bone black, lose their colour, in
consequence of the colouring particles combining by a kind of capillary
attraction with the porous carbon, without undergoing any change. The
same thing happens when well-scoured wool is steeped in such coloured
liquids; and the colours which the wool assumes by its attraction for
the dye, is, with regard to most of the above coloured solutions, but
feeble and fugitive, since the dye may be again abstracted by copious
washing with simple water, whose attractive force therefore overcomes
that of the wool. The aid of a high temperature, indeed, is requisite
for the abstraction of the colour from the wool and the bone-black,
probably by enlarging the size of the pores, and increasing the solvent
power of the water.

Those dye-baths, on the contrary, whose colouring matter is of the
nature of extractive or apothème, form a faster combination with stuffs.
Thus the yellow, fawn, and brown dyes, which contain tannin and
extractive, become oxygenated by contact of air, and insoluble in water;
by which means they can impart a durable dye. When wool is impregnated
with decoctions of that kind, its pores get charged by capillarity, and
when the liquid becomes oxygenated, they remain filled with a colour now
become insoluble in water. A similar change to insolubility ensues when
the yellow liquor of the indigo vat gets oxidized in the pores of cotton
and wool, into which it had been introduced in a fluid state. The same
change occurs when protosulphate of iron is converted into persulphate,
with the deposition of an insoluble peroxide in the substance of the
stuff. The change here effected by oxidation can, in other
circumstances, be produced by acids which have the power of
precipitating the dye-stuff in an insoluble state, as happens with
decoction of fustic.

Hence we perceive that the dyeing of fast colours rests upon the
principle, that the colours dissolved in the vat, during their union
with the stuff, should suffer such a change as to become insoluble in
their former menstruum. The more this dye, as altered in its union with
the stuff, can resist other menstrua or agents, the faster it will be.
This is the essential difference between dyeing and painting; or
applying a coat of pigment devoid of any true affinity for the surface.

If we mix a clear infusion of a dye with a small quantity of a solution
of an earthy or metallic salt, both in water, the limpid liquids soon
become turbid, and there gradually subsides sooner or later, according
to the nature of the mixture, a coloured precipitate, consisting of the
altered dye united with a basic or subsalt. In this compound the
colouring matter seems to act the part of an acid, which is saturated by
a small quantity of the basis, or in its acid relationship is feeble, so
that it can also combine with acids, being in reference to them a base.
The decomposition of a salt, as alum, by dyes, is effected principally
through the formation of an insoluble subsalt, with which the colour
combines, while a supersalt remains in the bath, and modifies, by its
solvent reaction, the shade of the dyed stuff. Dyed stuffs may be
considered as composed of the fibrous body intimately associated with
the colouring matter, the oxide, and acid, all three constituting a
compound salt. Many persons have erroneously imagined, that dyed goods
contained none of the acid employed in the dye bath; but they forget
that even potash added to alum does not throw down the pure earthy
basis, but a subsalt; and they should not ascribe to colouring matter a
power of decomposition at all approaching to that of an alkali. Salts,
containing strong acids, saturate a very large quantity of colouring
matter, in proportion to their place in the scale of chemical
equivalents. Mere bases, such as pure alumina, and pure oxide of tin,
have no power of precipitating colouring matter; when they seem to do
so, they always contain some acid.

Such salts, therefore, as have a tendency to pass readily into the basic
state, are peculiarly adapted to act as mordants in dyeing, and to form
coloured lakes. Magnesia affords as fine a white powder as alumina, and
answers equally well to dilute lakes, but its soluble salts cannot be
employed to form lakes, because they do not pass into the basic state.
This illustration is calculated to throw much light upon dyeing
processes in general.

The colour of the lake depends very much upon the nature of the acid,
and the basis of the precipitating salt. If it be white, like alumina
and oxide of tin, the lake will have, more or less, the colour of the
dye, but brightened by the reflection of white light from the basis;
while the difference of the acid occasions a difference in the hue. The
coloured bases impart more or less of their colour to the lakes, not
merely in virtue of their own tints, but of their chemical action upon
the dye.

Upon these principles a crimson precipitate is obtained from infusions
of cochineal by alum and salt of tin, which becomes scarlet by the
addition of tartar; by acetate of lead, a violet blue precipitate is
obtained, which is durable in the air; by muriate of lime, a pink brown
precipitate falls, which soon becomes black, and at last dirty green; by
the solution of a ferruginous salt, the precipitates are dark violet,
and black; and, in like manner, all other salts with earthy or metallic
bases, afford diversities of shade with cochineal. If this dye stuff be
dissolved in weak water of ammonia, and be precipitated with acetate of
lead, a green lake is obtained, which, after some time, will become
green on the surface by contact of air, but violet and blue beneath.
Hence it appears, that the shade of colour of a lake depends upon the
degree of oxidation or change of the colour caused by the acid of the
precipitating salt, upon the degree of oxidation or colour of the oxide
which enters into union with the dye, and upon its quantity in reference
to that of the colouring principle.

Such lakes are the difficultly soluble salts which constitute the dyeing
materials of stuffs. Their particles, however, for the purposes of
dyeing, must exist in a state of extremely fine division in the bath
liquor, in order that they may penetrate along with it into the minute
pores of textile fibres, and fill the cavities observed by means of the
microscope in the filaments of wool, silk, cotton, and flax. I have
examined these stuffs with an achromatic microscope, and find that when
they are properly dyed with fast colours, the interior of their tubular
texture is filled, or lined at least, with colouring matter. When the
bath contains the colouring particles, so finely divided that they can
pass through filtering paper, it is capable of dyeing; but if the
infusion mixed with its mordant be flocculent and ready to subside, it
is unfit for the purpose. In the latter case, the ingredients of the dye
have already become aggregated into compounds too coherent and too gross
for entering into combination with fibrous stuffs. Extractive matter and
tannin are particularly liable to a change of this kind, by the
prolonged action of heat in the bath. Hence also an alkaline solution of
a colouring matter, affords no useful dye bath, when mixed with the
solution of a salt having an earthy or metallic basis.

These circumstances, which are of frequent occurrence in the dye-house,
render it necessary always to have the laky matter in a somewhat soluble
condition, and to effect its precipitation within the pores of the
stuffs, by previously impregnating them with the saline solutions by the
aid of heat, which facilitates their introduction.

When a mordant is applied to any stuff, the portion of it remaining upon
the surface of the fibres should be removed; since, by its combination
with the colouring matter, it would be apt to form an external crust of
mere pigment, which would block up the pores, obstruct the entrance of
the dye into the interior, and also exhaust to no purpose the dyeing
power of the bath. For this reason the stuffs, after the application of
the mordant, are drained, squeezed, washed, and sometimes (particularly
with cotton and linen, in calico printing), even hard dried in a hot
stove.

The saline mordants, moreover, should not in general possess the
crystallizing property in any considerable degree, as this opposes their
affinity of composition for the cloth. On this account the deliquescent
acetates of iron and alumina are more ready to aid the dyeing of cotton
than copperas and alum.

Alum is the great mordant employed in wool dyeing. It is frequently
dissolved in water, holding tartar equal to one fourth the weight of the
alum in solution; by which addition its tendency to crystallize is
diminished, and the resulting colour is brightened. The alum and tartar
combine with the stuff without suffering any change, and are decomposed
only by the action of the colouring matters in the dye bath. The alum
operates solely in virtue of its sulphuric acid, and earthy basis; the
sulphate of potash present in that salt being rather injurious. Hence,
if a sulphate of alumina free from iron could be readily obtained, it
would prove a preferable mordant to alum. It is also probable, for the
reason above assigned, that soda alum, a salt much less apt to
crystallize than potash or ammonia alum, would suit the dyer very well.
In order to counteract the tendency of common alum to crystallize, and
to promote its tendency to pass into a basic salt, one eighth part of
its weight of potash is added to its solution, or the equivalent in
chalk or soda.

We shall conclude this account of the general principles of dyeing, with
Mr. Delaval’s observations on the nature of dyes, and a list of the
different substances used in dyeing, in reference to the colours
produced by them.

Sir Isaac Newton supposed coloured matters to reflect the rays of light;
some bodies reflecting the more, others the less, refrangible rays most
copiously; and this he conceived to be the true, and the only reason of
their colours. Mr. Delaval, however, proved in the 2d vol. of the
“Memoirs of the Philosophical and Literary Society of Manchester,” that,
“in transparent coloured substances, the colouring substance does not
reflect any light; and that when, by intercepting the light which was
transmitted, it is hindered from passing through substances, they do not
vary from their former colour to any other colour, but become entirely
black;” and he instances a considerable number of coloured liquors, none
of them endued with reflective powers, which, when seen by transmitted
light, appeared severally in their true colours; but all of them, when
seen by incident light, appeared black; which is also the case of black
cherries, black currants, black berries, &c., the juices of which
appeared red when spread on a white ground, or otherwise viewed by
transmitted instead of incident light; and he concludes, that bleached
linen, &c. “when dyed or painted with vegetable colours, do not differ
in their manner of acting on the rays of light, from natural vegetable
bodies; both yielding their colours by transmitting through the
transparent coloured matter, the light which is reflected from the white
ground:” it being apparent, from different experiments, “that no
reflecting power resides in any of their components, except in their
white matter only,” and that “transparent coloured substances, placed in
situations by which transmission of light through them is intercepted,
exhibit no colour, but become entirely black.”

The art of dyeing, therefore, (according to Mr. Delaval) “consists
principally in covering white substances, from which light is strongly
reflected, with transparent coloured media, which, according to their
several colours, transmit more or less copiously the rays reflected from
the white,” since “the transparent media themselves reflect no light;
and it is evident that if they yielded their colours by reflecting,
instead of transmitting the rays, the whiteness or colour of the ground
on which they are applied, would not in anywise alter or affect the
colours which they exhibit.”

But when any opaque basis is interposed, the reflection is doubtless
made by it, rather than by the substance of the dyed wool, silk, &c.,
and more especially when such basis consists of the white earth of alum,
or the white oxide of tin; which, by their strong reflective powers,
greatly augment the lustre of colours. There are, moreover, some opaque
colouring matters, particularly the acetous, and other solutions of
iron, used to stain linen, cotton, &c., which must necessarily
themselves reflect, instead of transmitting the light by which their
colours are made perceptible.

The compound or mixed colours, are such as result from the combination
of two differently coloured dye stuffs, or from dyeing stuffs with one
colour, and then with another. The simple colours of the dyer, are red,
yellow, blue, and black, with which, when skilfully blended, he can
produce every variety of tint. Perhaps the dun or fawn colour might be
added to the above, as it is directly obtained from a great many
vegetable substances.

1. Red with yellow, produces orange; a colour, which upon wool, is given
usually with the spent scarlet bath. To this shade may be referred flame
colour, pomegranate, capuchin, prawn, jonquil, _cassis_, chamois, _café
au lait_, aurora, marigold, orange peel, _mordorés_, cinnamon, gold, &c.
Snuff, chesnut, musk, and other shades are produced by substituting
walnut peels or sumach for bright yellow. If a little blue be added to
orange, an olive is obtained. The only direct orange dyes are annotto,
and subchromate of lead; see SILK and WOOL Dyeing.

2. Red with blue produces purple, violet, lilac, pigeon’s neck, mallow,
peach-blossom, _bleu de roi_, lint-blossom, amaranth.

3. Red with black; brown, chocolate, marone, &c.

4. Yellow with blue; green of a great variety of shades; such as nascent
green, gay green, grass green, spring green, laurel green, sea green,
celadon green, parrot green, cabbage green, apple green, duck green.

5. Mixtures of colours, three and three, and four and four, produce an
indefinite diversity of tints; thus red, yellow and blue, form brown
olives, and greenish grays; in which the blue dye ought always to be
first given, lest the indigo vat should be soiled by other colours. Red,
yellow, and gray, (which is a gradation of black), give the dead-leaf
tint, as well as dark orange, snuff colour, &c. Red, blue and gray give
a vast variety of shades; as lead gray, slate gray, wood-pigeon gray,
and other colours, too numerous to specify. See BROWN DYE.

The following list of dyes, and the colouring substances which produce
them, may prove useful.

_Red._ Cochineal, kermes, lac, madder, archil, carthamus or safflower,
brazil wood, logwood, periodide of mercury, alkanet.

_Yellow._ Quercitron, weld, fustic (yellow wood), annotto, sawwort,
dyer’s broom, turmeric, fustet (_rhus cotinus_), Persian and Avignon
berries (_rhamnus infectorius_), willow, peroxide of iron; chromate of
lead (chrome yellow), sulphuret of arsenic, hydrosulphuret of antimony;
nitric acid on silk.

_Blue._ Indigo, woad or pastel, Prussian blue, turnsole or litmus,
logwood with a salt of copper.

_Black._ Galls, sumach, logwood, walnut peels, and other vegetables
which contain tannin and gallic acid, along with ferruginous mordants.
The anacardium of India.

_Green._ These are produced by the blue and yellow dyes skilfully
combined; with the exception of the chrome green, and perhaps the copper
green of Schweinfurt.

_Orange._ Annotto, and mixtures of red and yellow dyes; subchromate of
lead.

_Brown._ See the remarks at the beginning of this article; BROWN in its
alphabetical place; CALICO PRINTING, CATECHU, and MANGANESE.

_Fawn, Dun or Root._ Walnut peels, sumach, birch tree, henna, sandal
wood. See CALICO PRINTING, for a great variety of these dyes.

_Fig._ 364. and 365. represent in a cross and longitudinal section the
automatic dyeing steam copper, so generally employed in the
well-appointed factories of Lancashire.

[Illustration: 364 365]

A is the long reel, composed at each end of six radial iron arms or
spokes, bound at their outer extremities with a six-sided wooden frame;
these two terminal hexagons are connected by long wooden laths, seen
above and below A in _fig._ 365. F shows the sloping border or ledge of
the copper. B and C are rollers laid horizontally, for facilitating the
continuous motion of the series of pieces of goods stitched together
into an endless web, which are made to travel by the incessant rotations
of the reel. Immediately above the roller B in _fig._ 364., all the
spare foldings of the web are seen resting upon the sloping wooden
grating, which guides them onwards in the direction indicated by the
arrow. The dye stuffs are put within the middle grating, like a
hen-coop, marked G. Each copper is 6 feet long, 3-1/2 feet wide, 3-1/2
feet deep, exclusive of the top ledge, 9 inches high. Such steam coppers
are usually erected in pairs, and moved by a common horizontal bevel
wheel seen at D in _fig._ 365., fixed upon a vertical shaft, shifted
into geer by a wheel at its top, with one of the driving shafts of the
factory. Upon each side of D, the two steam pipes for supplying the
right and left hand coppers are seen; each provided with a stop cock for
admitting, regulating, or cutting off the steam. These steam pipes
descend at E E, the horizontal branch having several orifices in its
upper surface. The horizontal shaft in a line with the axes of the
reels, and which turns them, is furnished upon each side with a clutch
for putting either of the reels into or out of geer, that is to say,
setting it a going, or at rest, in a moment by the touch of a forked
lever.

The steam pipe of distribution E lies horizontally near the bottom of
the middle coop, as shown under G in _fig._ 364., and sends up the steam
through its numerous orifices, among the dye-stuffs and water by which
it is covered. Thus the infusion or decoction is continually advancing
in the copper, during the incessant loco-motion of the endless web. The
horizontal pipe traverses the copper from end to end, and is not stopped
short in the middle. Each of these coppers can receive two, three or
more parallel pieces of goods at a time, the reel and copper being
divided into so many compartments by transverse wooden spars.




E.


EARTHS. (_Terres_, Fr.; _Erden_, Germ.) Modern science has demonstrated
that the substances called primitive earths, and which prior to the
great electro-chemical career of Sir H. Davy, were deemed to be
elementary matter, are all compounds of certain metallic bases and
oxygen, with the exception of silica, whose base, silicon, being
analogous to boron, has led that compound to be regarded as an acid; a
title characteristic of the part it extensively performs in neutralizing
alkaline bodies, in mineral nature, and in the processes of art. Four of
the earths, when pure, possess decided alkaline properties, being more
or less soluble in water, having (at least 3 of them) an acrid alkaline
taste, changing the purple infusion of red cabbage to green, most
readily saturating the acids, and affording thereby neutro-saline
crystals. These four are _baryta_, _strontia_, _lime_ (_calcia_), and
_magnesia_. The earths proper are five in number; _alumina_, _glucina_,
_yttria_, _zirconia_, and _thorina_. These do not change the colour of
infusion of cabbage or tincture of litmus, do not readily neutralize
acidity, and are quite insoluble in water. The alkalies are soluble in
water, even when carbonated; a property which distinguishes them from
the alkaline earths. _Lithia_ must for this reason be considered to be
an alkali. See the above substances in their alphabetical places.


EAU DE COLOGNE. This preparation has long possessed great celebrity, in
consequence chiefly of the numerous virtues ascribed to it by its
venders; and is resorted to by many votaries of fashion as a panacea
against ailments of every kind. It is however nothing more than
aromatized alcohol, and as such, an agreeable companion of the toilet.
Numerous fictitious recipes have been offered for preparing _eau de
Cologne_; the following may be reckoned authentic, having been imparted
by Farina himself to a friend.

Take 60 gallons of silent brandy; sage, and thyme, each 6 drachms;
balm-mint and spearmint, each 12 ounces; calamus aromaticus, 4 drachms;
root of angelica, 2 drachms; camphor, 1 drachm; petals of roses and
violets, each 4 ounces; flowers of lavender, 2 ounces; flowers of
orange, 4 drachms; wormwood, 1 ounce; nutmegs, cloves, cassia lignea,
mace, each 4 drachms. Two oranges and two lemons, cut in pieces. Allow
the whole to macerate in the spirit during 24 hours, then distil off 40
gallons by the heat of a water bath. Add to the product:

Essence of lemons, of cedrat, of balm-mint, of lavender, each 1 ounce 4
drachms; neroli and essence of the seed of anthos, each 4 drachms;
essence of jasmin, 1 ounce; of bergamot, 12 ounces. Filter and preserve
for use.

Cadet Gassincourt has proposed to prepare _eau de Cologne_ by the
following recipe: Take alcohol at 32° B., 2 quarts; neroli, essence of
cedrat, of orange, of lemon, of bergamot, of rosemary, each 24 drops;
add 2 drachms of the seeds of lesser cardamoms, distil by the heat of a
water bath a pint and a half. When prepared as thus by simple mixture of
essences without distillation, it is never so good.


EAU DE LUCE, is a compound formed of the distilled oil of amber and
water of ammonia.


ELEMI, is a resin which exudes from incisions made during dry weather
through the bark of the _amyris elemifera_, a tree which grows in South
America and Brazil. It comes to us in yellow, tender, transparent lumps,
which readily soften by the heat of the hand. They have a strong
aromatic odour, a hot spicy taste, and contain 12-1/2 per cent. of
ethereous oil. The crystalline resin of elemi has been called _Elémine_.
It is used in making lacquer, to give toughness to the varnish.


EBULLITION. (Eng. and Fr.; _Kochen_, Germ.) When the bottom of an open
vessel containing water is exposed to heat, the lowest stratum of fluid
immediately expands, becomes therefore specifically lighter, and is
forced upwards by the superior gravity of the superincumbent colder and
heavier particles. The heat is in this way diffused through the whole
liquid mass, not by simple communication of that power from particle to
particle as in solids, called the _conduction_ of caloric, but by a
translation of the several particles from the bottom to the top, and the
top to the bottom, in alternate succession. This is denominated the
_carrying_ power of fluids, being common to both liquid and gaseous
bodies. These internal movements may be rendered very conspicuous and
instructive, by mingling a little powdered amber with water, contained
in a tall glass cylinder, standing upon a sand-bath. A column of the
heated and lighter particles will be seen ascending near the axis of the
cylinder, surrounded by a hollow column of the cooler ones descending
near the sides. That this molecular translation or loco-motion is almost
the sole mode in which fluids get heated, may be demonstrated by placing
the middle of a pretty long glass tube, nearly filled with water,
obliquely over an argand flame. The upper half of the liquid will soon
boil, but the portion under the middle will continue cool, so that a
lump of ice may remain for a considerable time at the bottom. When the
heat is rapidly applied, the liquid is thrown into agitation, in
consequence of elastic vapour being suddenly generated at the bottom of
the vessel, and being as suddenly condensed at a little distance above
it by the surrounding cold columns. These alternate expansions and
contractions of volume become more manifest as the liquid becomes
hotter, and constitute the _simmering_ vibratory sound which is the
prelude of ebullition. The whole mass being now heated to a pitch
compatible with its permanent elasticity, becomes turbulent and
explosive under the continued influence of fire, and emitting more or
less copious volumes of vapour is said to boil. The further elevation of
temperature, by the influence of caloric, becomes impossible in these
circumstances with almost all liquids, because the vapour carries off
from them as much heat in a latent state as they are capable of
receiving from the fire.

The temperature at which liquids boil in the open air varies with the
degree of atmospheric pressure, being higher as that is increased, and
lower as it is diminished. Hence boiling water is colder by some degrees
in bad weather, or in an elevated situation, with a depressed barometer,
than in fine weather, or at the bottom of a coal-pit, when the barometer
is elevated. A high column of liquid also by resisting the discharge of
the steam raises the boiling point. In _vacuo_, all liquids boil at a
temperature about 124° F. lower than under the average atmospheric
pressure. For a table of elasticities, see VAPOUR. Gay Lussac has shown
that liquids are converted into vapours more readily or with less
turbulence, when they are in contact with angular or irregular, than
with smooth surfaces; that they therefore boil at a heat 2° F. lower in
metallic than in glass vessels, probably owing to the greater polish of
the latter. For example, if into water about to boil in a glass matras,
iron filings, ground glass, or any other insoluble powder be thrown,
such a brisk ebullition will be instantly determined, as will sometimes
throw the water out of the vessel; the temperature at the same time
sinking two degrees F. It would thence appear that the power of caloric,
like that of electricity, becomes concentrated by points.

The following table exhibits the boiling heats, by Fahrenheit’s scale,
of the most important liquids:--

  Ether, specific gravity 0·7365 at 48°                          100°
  Carburet of sulphur,                                           113
  Alcohol, sp. grav. 0·813                            Ure,       173·5
  Nitric acid,       1·500                            Dalton,    210
  Water,                                                         212
  Saturated solution of Glauber salt,                 Biot,      213-1/3
    do.       do.       Acetate of lead               do.        215-2/3
    do.       do.       Sea salt                      do.        224-1/3
    do.       do.       Muriate of lime,              Ure,       285
    do.       do.       do.          1   + water 2,   do.        230
    do.       do.       do.         35·5 + do.  64·5, do.        235
    do.       do.       do.         40·5 + do.  59·5, do.        240
  Muriatic acid, sp. grav. 1·094                      Dalton,    232
    do.          do.       1·127                      do.        222
  Nitric acid,   do.       1·420                      do.        248
    do.          do.       1·30                       do.        236
  Rectified petroleum                                 Ure,       306
  Oil of turpentine                                   do.        316
  Sulphuric acid, sp. grav. 1·848                     Dalton,    600
    do.           do.       1·810                     do.        473
    do.           do.       1·780                     do.        435
    do.           do.       1·700                     do.        374
    do.           do.       1·650                     do.        350
    do.           do.       1·520                     do.        290
    do.           do.       1·408                     do.        260
    do.           do.       1·300+                    do.        240
  Phosphorus                                          do.        554
  Sulphur                                             do.        570
  Linseed oil                                         do.        640
  Mercury                                             Dulong,    662
    do.                                               Crighton,  656
  Saturated solution of
            acetate of soda, containing 60 per cent.  Griffiths, 256
    do.     Nitrate of soda,            60            do.        246
    do.     Rochelle salt,              90            do.        240
    do.     Nitre,                      74            do.        238
    do.     Muriate of ammonia,         50            do.        236
    do.     Tartrate of potash,         68            do.        234
    do.     Muriate of soda,            30            do.        224
    do.     Sulphate of magnesia,       57·5          do.        222
    do.     Borax,                      52·5          do.        222
    do.     Phosphate of soda,           ?            do.        222
    do.     Carbonate of soda,           ?            do.        220
    do.     Alum,                       52            do.        220
    do.     Chlorate of potash,         40            do.        218
    do.     Sulphate of copper,         45            do.        216


EDULCORATE, (_Edulcorer_, Fr.; _Aussüssen_, Germ.) is a word introduced
by the alchemists to signify the sweetening, or rather rendering
insipid, of acrimonious pulverulent substances, by copious ablutions
with water. It means, in modern language, the washing away of all
particles soluble in water, by agitation or trituration with this fluid,
and subsequent decantation or filtration.


EFFERVESCENCE. (Eng. and Fr.; _Aufbrausen_, Germ.) When gaseous matter
is suddenly extricated with a hissing sound during a chemical mixture,
or by the application of a chemical solvent to a solid, the phenomenon,
from its resemblance to that of simmering or boiling water, is called
effervescence. The most familiar example is afforded in the solution of
sodaic powders; in which the carbonic acid gas of sesquicarbonate of
soda, is extricated by the action of citric, or tartaric acid.


EFFLORESCENCE, (Eng. and Fr.; _Verwittern_, Germ.) is the spontaneous
conversion of a solid, usually crystalline, into a powder, in
consequence either of the abstraction of the combined water by the air,
as happens to the crystals of sulphate and carbonate of soda; or by the
absorption of oxygen and the formation of a saline compound, as in the
case of alum schist, and iron pyrites. Saltpetre appears as an
efflorescence upon the ground and walls in many situations.


EDGE-TOOLS. See CUTLERY and STEEL.


EGGS, HATCHING. See INCUBATION, ARTIFICIAL.


EIDER-DOWN, is a kind of precious down, so called because it is obtained
from the EIDER-duck. These birds build their nests among precipitous
rocks, and the female lines them with fine feathers plucked from her
breast, among which she lays her five eggs. The natives of the districts
frequented by the eider-ducks let themselves down by cords among the
dangerous cliffs, to collect the down from the nests. It is used to fill
coverlets, pillows, cushions, &c.


ELAINE is the name given by Chevreul to the thin oil, which may be
expelled from tallow, and other fats, solid or fluid, by pressure either
in their natural state, or after being saponified, so as to harden the
_stearine_. It may be extracted also by digesting the fat in 7 or 8
times its weight of boiling alcohol, spec. grav. 0·798, till it
dissolves the whole. Upon cooling the solution, the stearine falls to
the bottom, while the elaine collects in a layer like olive oil, upon
the surface of the supernatant solution, reduced by evaporation to one
eighth of its bulk. If this elaine be now exposed to a cold temperature,
it will deposit its remaining stearine, and become pure. See FAT, OILS,
and STEARINE.


ELASTIC BANDS. (_Tissus Elastiques_, Fr.; _Federharz-zeige_, Germ.) The
manufacture of braces and garters, with threads of caoutchouc, either
naked or covered, seems to have originated, some time ago, in Vienna,
whence it was a few years since imported into Paris, and thence into
this country. At first the pear-shaped bottle of Indian rubber was cut
into long narrow strips by the scissors; a single operative turning off
only about 100 yards in a day, by cutting the pear in a spiral
direction. He succeeded next in separating with a pair of pincers the
several layers of which the bottle was composed. Another mode of
obtaining fine threads was to cut them out of a bottle which had been
rendered thin by inflation with a forcing pump. All these operations are
facilitated by previously steeping the caoutchouc in boiling water, in
its moderately inflated state. More recently, machines have been
successfully employed for cutting out these filaments, but for this
purpose the bottle of caoutchouc is transformed into a disc of equal
thickness in all its parts, and perfectly circular. This preliminary
operation is executed as follows: 1. the bottle, softened in hot water,
is squeezed between the two plates of a press, the neck having been
removed beforehand, as useless in this point of view; 2. the bottle is
then cut into two equal parts, and is allowed to consolidate by cooling
before subjecting it to the cutting instrument. When the bottle is
strong enough, and of variable thickness in its different points, each
half is submitted to powerful pressure in a very strong cylindrical
mould of metal, into which a metallic plunger descends, which forces the
caoutchouc to take the form of a flat cylinder with a circular base. The
mould is plunged into hot water during the compression. A stem or rod of
iron, which goes across the hollow mould and piston, retains the latter
in its place, notwithstanding the resilience of the caoutchouc, when the
mould is taken from the press. The mould being then cooled in water, the
caoutchouc is withdrawn.

The transformation of the disc of caoutchouc into fine threads is
performed by two machines; the first of which cuts it into a riband of
equal thickness in its whole extent, running in a spiral direction from
the circumference to the centre; the second subdivides this riband
lengthwise into several parallel filaments much narrower but equally
thick.

[Illustration: 366 367 368]

The following _figs._ 366, 367, 368. represent the machine for cutting
the spiral riband. The disc D, placed horizontally, turns round its
vertical axis, so as to present its periphery to the edge of a knife C,
formed like a circular blade, whose plane is perpendicular to that of
the bases of the disc. This knife turns round its centre, which is
fixed. The rotatory motion of the disc forces the knife to penetrate
further and further into its mass, and the motion of the knife itself
makes it cut the riband more easily. It is obvious, that if the disc
alone revolved, the motionless knife could act only by pressure, and
would meet with an enormous resistance. A third movement becomes
necessary. In proportion as the disc is diminished by the removal of the
spiral band, the centre of this disc must advance upon the knife, in
order that the riband may have always the same breadth. The inspection
of _fig._ 368. will make the accordance of the three motions
intelligible.

The knife C is placed upon a shaft or axis A, which carries a pulley,
round which a belt or cord runs which drives the whole machine. This
knife is six inches in diameter. In order that by being kept cool it may
cut the caoutchouc better, it is plunged at its lower part into a trough
B, full of water; a stopcock R, serves to empty this trough.

The shaft A bears a pinion p, which takes into a wheel R, placed upon
the shaft A´; upon which there is cut a worm or endless screw, V, V.
This worm bears a nut E, which advances as the screw turns, and carries
with it a tie L, which in its turn pushes the disc D, carried upon a
shoulder constantly towards the knife. This shoulder is guided by two
ears which slide in two grooves cut in the thickness of the table. The
diameter of the pinion p is about one fifth of that of the wheel R; so
that the arbour A turns five times less quickly than the arbour A; and
the fineness of the screw V contributes further to slacken the movement
of translation of the disc.

When the disc is all cut down, the shoulder, the tie, and the nut, are
brought back to their original position by lifting the nut, which is
hinged on. The disc is fixed upon the shoulder by means of sharp points,
and an upper washer. The shoulder and the washer have a very small
diameter, in order that the knife may, in cutting down the disc, advance
as near as possible to the centre.

The rotatory movement of the disc and its shoulder, is given by an
endless screw W, W, which governs a pinion _p´_, provided with 10 teeth,
and carried by the shaft A, upon which the shoulder is mounted. The
arbour A´ of this endless screw receives its motion from the first shaft
A, by means of the wheels S and S´ mounted upon these shafts, and of an
intermediate wheel S´´. This wheel, of a diameter equal to that of the
shaft A´´, is intended merely to allow this shaft to recede from the
shaft A. The diameter of the wheel of this last shaft is to that of the
two others in the ratio of 10 to 8.

[Illustration: 369]

_Second machine for sub-dividing the ribands._ _Fig._ 369.--The riband
is engaged between the circular knives, C, C, which are mounted upon the
rollers R, R; thin brass washers keep these knives apart at a distance
which may be varied, and two extreme washers mounted with screws on each
roller maintain the whole system. The axes of these rollers traverse two
uprights M, M, furnished with brasses, and with adjusting screws to
approximate them at pleasure. The axis of the lower roller carries a
wheel _r_, which takes into another smaller wheel _r´_, placed upon the
same shaft as the pulley P, which is driven by a cord. The diameter of
the wheel _r_ is three times greater than the wheel _r´_. The pulley P
is twice the size of the wheel _r´_; and its cord passes round a drum B,
which drives the rest of the machine.

The threads when brought to this state of slenderness, are put
successively into tubs filled with cold water; they are next softened in
hot water, and elongated as much as possible in the following
manner:--They are wound upon a reel turned quickly, while the operative
stretches the caoutchouc thread with his hand. In this way it is
rendered 8 or 10 times longer. The reels when thus filled are placed
during some days in a cold apartment, where the threads become firm, and
seem to change their nature.

This state of stiffness is essential for the success of the subsequent
operations. The threads are commonly covered with a sheath of silk,
cotton, or linen, by a braiding machine, and are then placed as warp in
a loom, in order to form a narrow web for braces, garters, &c. If the
gum were to exercise its elasticity during this operation, the different
threads would be lengthened and shortened in an irregular manner, so as
to form a puckered tissue. It is requisite therefore to weave the
threads in their rigid and inextensible, or at least incontractile
condition, and after the fabric is woven to restore to the threads of
caoutchouc their appropriate elasticity. This restoration is easily
effected by passing a hot smoothing iron over the tissue laid smoothly
upon a table covered with blanket stuff. See BRAIDING MACHINE.


ELECTIVE AFFINITY, (_Wahlverwandtschaft_, Germ.) denotes the order of
preference, so to speak, in which the several chemical substances
_choose_ to combine; or really, the gradation of attractive force
infused by Almighty Wisdom among the different objects of nature, which
determines perfect uniformity and identity in their compounds amidst
indefinite variety of combination. The discussion of this interesting
subject belongs to pure chemistry. See DECOMPOSITION.


ELEMENTS (Eng. and Fr.; _Grundstoffe_, Germ.) The ancients considered
fire, air, water, and earth, as simple substances, essential to the
constitution of all terrestrial beings. This hypothesis, evidently
incompatible with modern chemical discovery, may be supposed to
correspond, however, to the four states in which matter seems to exist;
namely, 1. the unconfinable powers or fluids,--caloric, light,
electricity; 2. ponderable gases, or elastic fluids; 3. liquids; 4.
solids. The three elements of the alchemists, salt, earth, mercury,
were, in _their_ sense of the word, mere phantasms.

In modern science, the term _Element_ signifies merely a substance which
has not yet been resolved by analysis into any simpler form of matter;
and it is therefore synonymous with undecompounded. This class
comprehends 54 different bodies, of which no less than 41 are metallic.
Five may be styled _Archæal_, from the intensity and universality of
their affinities for the other bodies, which they penetrate, corrode,
and apparently consume, with the phenomena of light and heat. These 5
are _chlorine_, _oxygen_, _iodine_, _bromine_, _fluorine_. Eight
elements are eminently inflammable when acted upon by any of the
preceding five, and are thereby converted into incombustible compounds.
The simple non-metallic inflammables are _hydrogen_, _azote_, _sulphur_,
_phosphorus_, _selenium_, _carbon_, _boron_, _silicon_.

The following table exhibits all the undecompounded bodies in
alphabetical order, with their prime equivalent numbers, atomic weights,
or reciprocal combining and saturating proportions, as given by
Berzelius, in reference to oxygen, reckoned 100,000.:--

_Table of undecompounded Bodies, or modern Chemical Elements._

A signifies Archæal; I, Inflammable; M, Metal.

  Aluminium      M.     171,167
  Antimony       --     806,542
  Arsenic        --     470,042
  Azote          I.      88,518
  Barium         M.     856,880
  Bismuth        --     886,000
  Boron          I.     135,983
  Bromine        A.     489,150
  Cadmium        M.     696,970
  Calcium        --     256,019
  Carbon         I.      76,437
  Cerium         M.     574,718
  Chlorine       A.     221,325
  Chromium       M.     351,819
  Cobalt         --     369,991
  Copper         --     395,695
  Fluorine       I.     116,900
  Gold           M.    1243,013
  Hydrogen       I.      62,398
  Iodine         A.     789,145
  Iridium        M.    1233,260
  Iron           --     339,213
  Lead           --    1294,489
  Lithium        --      81,320
  Magnesium      --     158,353
  Manganesium    --     345,900
  Mercury        M.    1265,822
  Molybdenum     --     598,525
  Nickel         --     369,675
  Osmium         --    1244,210
  Oxygen         A.     100,000
  Palladium      M.     665,840
  Phosphorus     I.     196,155
  Platinum       M.    1233,260
  Rhodium        --     651,400
  Selenium       I.     494,582
  Silicon        --     277,478
  Silver         M.     675,804
  Strontium      --     547,285
  Sulphur        I.     201,165
  Tantalum       M.    1153,715
  Tellurium      --     801,760
  Thorinum       --     744,900
  Tin            --     735,294
  Titanium       --     303,686
  Tungsten       --    1183,000
  Uranium        --    2711,360
  Vanadium       --     855,840
  Yttrium        --     401,840
  Zinc           --     403,226
  Zirconium      --     420,238


ELUTRIATE. (_Soutirer_, Fr.; _Schlemmen_, Germ.) When an insoluble
pulverulent matter, like whitening or ground flints, is diffused through
a large body of water, and the mixture is allowed to settle for a
little, the larger particles will subside. If the supernatant liquid be
now carefully decanted, or run off, with a syphon, it will contain an
impalpable powder, which on repose will collect at the bottom, and may
be taken out to dry. This process is called elutriation.


EMBALMING. (_Embaument_, Fr.; _Einbalsamen_, Germ.) Is an operation in
which balsams (_baumes_, Fr.) were employed to preserve human corpses
from putrefaction; whence the name.

The ancient Egyptians had recourse to this process for preserving the
bodies of numerous families, and even of the animals which they loved or
worshipped. An excellent account of their methods is given in Mr.
Pettigrew’s work upon Mummies. Modern chemistry has made us acquainted
with many means of counteracting putrefaction more simple and
efficacious than the Egyptian system of salting, smoking, spicing, and
bituminizing. See PUTREFACTION.


EMBOSSING WOOD. (_Bossage_, Fr.; _Erhabenes Arbeit_, Germ.) Raised
figures upon wood, such as are employed in picture frames and other
articles of ornamental cabinet work, are usually produced by means of
carving, or by casting the pattern in plaster of Paris, or other
composition, and cementing, or otherwise fixing it on the surface of the
wood. The former mode is expensive; the latter is inapplicable on many
occasions. The invention of Mr. Streaker may be used either by itself,
or in aid of carving; and depends on the fact, that if a depression be
made by a blunt instrument on the surface of the wood, such depressed
part will again rise to its original level by subsequent immersion in
the water.

The wood to be ornamented having been first worked out to its proposed
shape, is in a state to receive the drawing of the pattern; this being
put on, a blunt steel tool, or burnisher, or die, is to be applied
successively to all those parts of the pattern intended to be in relief,
and, at the same time, is to be driven very cautiously, without breaking
the grain of the wood, till the depth of the depression is equal to the
intended prominence of the figures. The ground is then to be reduced by
planing or filing to the level of the depressed part; after which, the
piece of wood being placed in water, either hot or cold, the part
previously depressed will rise to its former height, and will then form
an embossed pattern, which may be finished by the usual operations of
carving.

For this invention the Society of Arts voted to Mr. Streaker their
silver Isis medal, and ten guineas.


EMBOSSING CLOTH. Mr. Thomas Greig, of Rose Bank, near Bury, patented an
invention, in November 1835, which consists in an ingenious construction
of machinery for both embossing and printing silk, cotton, woollen
cloth, paper, and other fabrics, in one or more colours, at one
operation.

[Illustration: 370 370*]

_Figs._ 370, 370* represent three distinct printing cylinders of copper,
or other suitable material, A, B, C, with their necessary appendages for
printing three different colours upon the fabric as it passes through
the machine: either of these cylinders A, B, or C, may be employed as an
embossing cylinder, without performing the printing process, or may be
made to effect both operations at the same time.

The fabric or goods to be operated upon being first wound tightly upon a
roller, that roller is to be mounted upon an axle or pivot, bearing in
arms or brackets at the back of the machine, as shown at D. From this
roller the fabric _a a a a_ is conducted between tension rails, and
passed under the bed cylinder or paper bowl E, and from thence proceeds
over a carrier roller F, and over steam boxes not shown in the drawing,
or it may be conducted into a hot room, for the purpose of drying the
colours.

The cylinders A, B, and C, having either engraved or raised surfaces,
are connected to feeding rollers _b b b_, revolving in the ink or
coloured troughs _c c c_; or endless felts, called sieves, may be
employed, as in ordinary printing machines, for supplying the colour,
when the device on the surface of the cylinders is raised: these
cylinders may be furnished with doctors or scrapers when required, or
the same may be applied to the endless felts.

The blocks have adjustable screws _g g_, for the purpose of bringing the
cylinders up against the paper bowl, with any required degree of
pressure: the cylinder B is supported by its gudgeons running in blocks,
which blocks slide in the lower parts of the side frames, and are
connected to perpendicular rods _i_, having adjustable screw nuts.

The lower parts of these rods bear upon weighted levers _k k_, extending
in front of the machine; and by increasing the weights _l l_, any degree
of upward pressure may be given to the cylinder B.

The colour boxes or troughs _c c c_, carrying the feeding rollers _b b
b_, are fixed on boards which slide in grooves in the side frames, and
the rollers are adjusted and brought into contact with the surface of
the printing cylinders by screws.

If a back cloth should be required to be introduced between the
cylindrical bed or paper bowl E, and the fabric _a a a_, as the ordinary
felt or blanket, it may, for printing and embossing cotton, silk, or
paper, be of linen or cotton; but if woollen goods are to be operated
upon, a cap of felt, or some such material, must be bound round the
paper bowl, and the felt or blanket must be used for the back cloth,
which is to be conducted over the rollers H and I.

For the purpose of embossing the fabric, either of the rollers A, B, or
C, may be employed, observing that the surface of the roller must be
cut, so as to leave the pattern or device elevated for embossing
velvets, plain cloths, and papers; but for woollens the device must be
excavated, that is, cut in recess.

The pattern of the embossing cylinder will, by the operation, be
partially marked through the fabric on to the surface of the paper bowl
E; to obliterate which marks from the surface of the bowl, as it
revolves, the iron cylinder roller G is employed; but as in the
embossing of the same patterns on paper, a counter roller is required to
produce the pattern perfectly, the iron roller is in that case dispensed
with, the impression given to the paper bowl being required to be
retained on its surface until the operation is finished.

In this case the relative circumferences of the embossing cylinder, and
of the paper bowl, must be exactly proportioned to each other; that is,
the circumference of the bowl must be equal, exactly, to a given number
of circumferences of the embossing cylinder, very accurately measured,
in order to preserve a perfect register or coincidence, as they continue
revolving between the pattern on the surface of the embossing cylinder,
and that indented into the surface of the paper bowl.

The axle of the paper bowl E, turns in brasses fitted into slots in the
side frames, and it may be raised by hand from its bearings when
required, by a lever _k_, extending in front. This lever is affixed to
the end of a horizontal shaft L, L, crossing the machine seen in the
figures, at the back of which shaft there are two segment levers P, P,
to which bent rods Q, Q, are attached, having hooks at their lower ends,
passed under the axle of the bowl. At the reverse end of the shaft L, a
ratchet-wheel _r_, is affixed, and a pall or click mounted on the side
of the frame takes into the teeth of the wheel _r_, and thereby holds up
the paper bowl when required.

When the iron roller G, is to be brought into operation, the vertical
screws _t_, _t_, mounted in the upper parts of the side frames, are
turned, in order to bring down the brasses N, which carry the axle of
that roller and slide in slots in the side frames.

The cylinders A, B, and C, are represented hollow, and may be kept at
any desired temperature during the operation of printing, by introducing
steam into them; and under the colour boxes _c_, _c_, _c_, hollow
chambers are also made for the same purpose. The degree of temperature
required to be given to these must depend upon the nature of the
colouring material, and of the goods operated upon. For the purpose of
conducting steam to these hollow cylinders and colour boxes, pipes, as
shown at _v_, _v_, _v_, are attached, which lead from a steam boiler.
But when either of these cylinders is employed for embossing alone, or
for embossing and printing at the same time, and particularly for some
kinds of goods where a higher temperature may be required, a red-hot
heater is then introduced into the hollow cylinder in place of steam.

If the cylinder B, is employed as the embossing cylinder, and it is not
intended to print the fabric by that cylinder simultaneously with the
operation of embossing, the feeding rolling _b_, must be removed, and
also the colour box _c_, belonging to that cylinder; and the cylinders
A, and C, are to be employed for printing the fabric, the one applying
the colour before the embossing is effected, the other after it. It is
however to be remarked, that if A, and C, are to print colours on the
fabric, and B, to emboss it, in that case it is preferred, where the
pattern would allow it. A and C, are wooden rollers having the pattern
upon their surfaces, and not metal, as the embossing cylinders must of
necessity be.

It will be perceived that this machine will print one, two, or three
colours at the same time, and that the operation of embossing may be
performed simultaneously with the printing, by either of the cylinders
A, B, or C, or the operation may be performed consecutively by the
cylinders, either preceding or succeeding each other.

The situations of the doctors, when required to be used for removing any
superfluous colour from the surface of the printing cylinder, are shown
at _d_, _d_, _d_; those for removing any lint which may attach itself,
at _e_, _e_, _e_. They are kept in their bearings by weighted levers and
screws, and receive a slight lateral movement to and fro, by means of
the vertical rod _m_, which is connected at top to an eccentric, on the
end of the axle of the roller H, and at its lower end to a horizontal
rod mounted at the side of the frame; to this horizontal rod, arms are
attached, which are connected to the respective doctors; and thus by the
rotation of the eccentric, the doctors are made to slide laterally.

When the cylinders A, B, or C, are employed for embossing only, those
doctors will not be required. The driving power is communicated to the
machine from any first mover through the agency of the toothed geer,
which gives rotatory motion to the cylinder B, and from thence to the
other cylinders A, and C, by toothed geer shown in _fig._ 370.


EMBROIDERING MACHINE. (_Machine à broder_, Fr.; _Steckmaschine_, Germ.)
This art has been till of late merely a handicraft employment,
cultivated on account of its elegance by ladies of rank. But a few years
ago M. Heilmann of Mulhausen invented a machine of a most ingenious
kind, which enables a female to embroider any design with 80 or 140
needles as accurately and expeditiously as she formerly could do with
one. A brief account of this remarkable invention will therefore be
acceptable to many readers. It was displayed at the national exposition
of the products of industry in Paris for 1834, and was unquestionably
the object which stood highest in public esteem; for whether at rest or
in motion, it was always surrounded with a crowd of curious visiters,
admiring the figures which it had formed, or inspecting its movements
and investigating its mechanism. 130 needles were occupied in copying
the same pattern with perfect regularity, all set in motion by one
person.

Several of these machines are now mounted in France, Germany, and
Switzerland. I have seen one factory in Manchester, where a great many
of them are doing beautiful work.

The price of a machine having 130 needles, and of consequence 260
pincers or fingers and thumbs to lay hold of them, is 5000 francs, or
200_l._ sterling; and it is estimated to do daily the work of 15 expert
hand embroiderers, employed upon the ordinary frame. It requires merely
the labour of one grown-up person, and two assistant children. The
operative must be well taught to use the machine, for he has many things
to attend to: with the one hand he traces out, or rather follows the
design with the point of the pantograph; with the other he turns a
handle to plant and pull all the needles, which are seized by pincers
and moved along by carriages, approaching to and receding from the web,
rolling all the time along an iron railway; lastly, by means of two
pedals, upon which he presses alternately with the one foot and the
other, he opens the 130 pincers of the first carriage, which ought to
give up the needles after planting them in the stuff, and he shuts with
the same pressure the 130 pincers of the second carriage, which is to
receive the needles, to draw them from the other side, and to bring them
back again. The children have nothing else to do than to change the
needles when all their threads are used, and to see that no needle
misses its pincers.

This machine deserves particular attention, because it is no less
remarkable for the happy arrangement of its parts, than for the effects
which it produces. It may be described under four heads: 1. the
structure of the frame; 2. the disposition of the web; 3. the
arrangement of the carriages; and 4. the construction of the pincers.

1. The structure of the frame. It is composed of cast-iron, and is very
massive. _Fig._ 371. exhibits a front elevation of it. The length of the
machine depends upon the number of pincers to be worked. The model at
the exposition had 260 pincers, and was 2 metres and a half (about 100
inches or 8 feet 4 inches English) long. The figure here given has been
shortened considerably, but the other proportions are not disturbed. The
breadth of the frame ought to be the same for every machine, whether it
be long or short, for it is the breadth which determines the length of
the thread to be put into the needles, and there is an advantage in
giving it the full breadth of the model machine, fully 100 inches, so
that the needles may carry a thread at least 40 inches long.

_Disposition of the piece to be embroidered._--We have already stated
that the pincers which hold the needles always present themselves
opposite to the same point, and that in consequence they would
continually pass backwards and forwards through the same hole, but the
piece is displaced with sufficient precision to bring opposite the tips
progressively of the needles, every point upon which they are to work a
design, such as a flower.

[Illustration: 371]

The piece is strained perpendicularly upon a large rectangular frame,
whose four sides are visible in _fig._ 371.; namely the two vertical
sides at F F, and the two horizontal sides, the upper and lower at F´
F´´. We see also in the figure two long wooden rollers G and G, whose
ends, mounted with iron studs, are supported upon the sides F of the
frame, so as to turn freely. These form a system of beams upon which the
piece destined to receive the embroidery, is wound and kept vertically
stretched to a proper degree, for each of these beams bears upon its end
a small ratchet wheel _g_, _g_; the teeth of one of them being inclined
in the opposite direction to those of the other. Besides this system of
lower beams, there is another of two upper beams, which is however but
imperfectly seen in the figure, on account of the interference of other
parts in this view of the machine. One of these systems presents the web
to the inferior needles, and the other to the upper needles. As the two
beams are not in the same vertical plane, the plane of the web would be
presented obliquely to the needles were it not for a straight bar of
iron, round whose edge the cloth passes, and which renders it vertical.
The piece is kept in tension crosswise by small brass templets, to which
the strings _g´´_ are attached, and by which it is pulled towards the
sides of the frame F. It remains to shew by what ingenious means this
frame may be shifted in every possible direction. M. Heilmann has
employed for this purpose the pantograph which draughtsmen use for
reducing or enlarging their plans in determinate proportions.

_b b´ f b´´_ (_fig._ 371.) represents a parallelogram of which the four
angles _b_, _b´_, _f_, _b´´_, are jointed in such a way that they may
become very acute or very obtuse at pleasure, while the sides of course
continue of the same length; the sides _b_, _b´_ and _b_, _b´´_ are
prolonged, the one to the point _d_, and the other to the point _c_, and
these points _c_ and _d_, are chosen under the condition that in one of
the positions of the parallelogram, the line _c d_ which joins them
passes through the point _f_; this condition may be fulfilled in an
infinite number of manners, since the position of the parallelogram
remaining the same, we see that if we wished to shift the point _d_
further from the point _b´_, it would be sufficient to bring the point c
near enough to _b´´_, or _vice versa_; but when we have once fixed upon
the distance _b´ d_, it is evident that the distance _b´´ c_ is its
necessary consequence. Now the principle upon which the construction of
the pantograph rests is this; it is sufficient that the three points
_d_, _f_, and _c_ be in a straight line, in one only of the positions of
the parallelogram, in order that they shall remain always in a straight
line in every position which can possibly be given to it.

We see in the figure that the side _b c_, has a handle B´´ with which
the workman puts the machine in action. To obtain more precision and
solidity in work, the sides of the pantograph are joined, so that the
middle of their thickness lies exactly in the vertical plane of the
piece of goods, and that the axes of the joints are truly perpendicular
to this plane, in which consequently all the displacements are effected.
We arrive at this result by making fast to the superior great cross bar
D´´ an elbow piece _d_², having a suitable projection, and to which is
adapted in its turn the piece _d´_, which receives in a socket the
extremity of the side _b_, _d_; this piece _d´_ is made fast to _d´´_ by
a bolt, but it carries an oblong hole, and before screwing up the nut,
we make the piece advance or recede, till the fulcrum point comes
exactly into the plane of the web. This condition being fulfilled, we
have merely to attach the frame to the angle _f_ of the parallelogram,
which is done by means of the piece F´´.

It is now obvious that if the embroiderer takes the handle B´´ in his
hand and makes the pantograph move in any direction whatever, the point
_f_ will describe a figure similar to the figure described by the point
_c_, and six times smaller, but the point _f_ cannot move without the
frame, and whatever is upon it moving also. Thus, in the movement of the
pantograph, every point of the web describes a figure equal to that
described by the point _f_, and consequently similar to that described
by the point _c_, but six times smaller; the embroidered object being
produced upon the cloth in the position of that of the pattern. It is
sufficient therefore to give the embroidering operative who holds the
handle B´´, a design six times greater than that to be executed by the
machine, and to afford him at the same time a sure and easy means of
tracing over with the point _c_, all the outlines of the pattern. For
this purpose he adapts to _c_, perpendicularly to the plane of the
parallelogram, a small style terminated by a point C´, and he fixes the
pattern upon a vertical tablet E, parallel to the plane of the stuff and
the parallelogram, and distant from it only by the length of the style
_c_ C´´; this tablet is carried by the iron rod _c´_, which is secured
to a cast iron foot E´, serving also for other purposes, as we shall
presently see. The frame loaded with its beams and its cloth forms a
pretty heavy mass, and as it must not swerve from its plane, it needs to
be lightened in order that the operative may cause the point of the
pantograph to pass along the tablet without straining or uncertainty in
its movements. M. Heilmann has accomplished these objects in the
following way. A cord _e_ attached to the side _b c_ of the pantograph
passes over a return pulley, and carries at its extremity, a weight
which may be graduated at pleasure; this weight equipoises the
pantograph, and tends slightly to raise the frame. The lower side of the
frame carries two rods H and H, each attached by two arms _h h_, a
little bent to the left; both of these are engaged in the grooves of a
pulley. Through this mechanism a pressure can be exercised upon the
frame from below upwards, which may be regulated at pleasure, and
without preventing the frame from moving in all directions, it hinders
it from deviating from the primitive plane to which the pantograph was
adjusted. The length of the rods H ought to be equal to the amount of
the lateral movement of the frame. Two guides _i i_ carried by two legs
of cast iron, present vertical slits in which the lower part of the
frame F´ is engaged.

_Disposition of the carriages._--The two carriages, which are similar,
are placed the one to the right, and the other to the left of the frame.
The carriage itself is composed merely of a long hollow cylinder of cast
iron L, carrying at either end a system of two grooved castors or
pulleys L´, which roll upon the horizontal rails K; the pulleys are
mounted upon a forked piece _l´_, with two ends to receive the axes of
the pulleys, and the piece _l´_ is itself bolted to a projecting ear _l_
cast upon the cylinder.

This assemblage constitutes properly speaking the carriage, resting in a
perfectly stable equilibrium upon the rails K, upon which it may be most
easily moved backwards and forwards, carrying its train of needles to be
passed or drawn through the cloth.

M. Heilmann has contrived a mechanism by which the operative without
budging from his place may conduct the carriages, and regulate as he
pleases the extent of their course, as well as the rapidity of their
movements. By turning the axes M´´ in the one direction or the other,
the carriage may be made to approach to, or recede from the web.

When one of the carriages has advanced to prick the needles into the
stuff, the other is there to receive them; it lays hold of them with its
pincers, pulls them through, performs its course by withdrawing to
stretch the thread, and close the stitch, then it goes back with the
needles to make its pricks in return. During these movements the first
carriage remains at its post waiting the return of the second. Thus the
two chariots make in succession an advance and a return, but they never
move together.

To effect these movements M. Heilmann has attached to the piece O´ made
fast to the two uprights A C and A D of the frame, a bent lever _n o n´
n´´_ movable round the point _o_; the bend _n´_ carries a toothed wheel
O´, and the extremity _n´´_ a toothed wheel O´´; the four wheels M M´ O´
and O´´ have the same number of teeth and the same diameter; the two
wheels O´ and O´´ are fixed in reference to each other, so that it is
sufficient to turn the handle N to make the wheel O´´ revolve, and
consequently the wheel O´; when the lever _n o_ is vertical, the wheel
O´ touches neither the wheel M nor the wheel M´; but if it be inclined
to the one side or the other, it brings the wheel O´ alternately into
geer with the wheel M or the wheel M´. As the operative has his two
hands occupied, the one with the pantograph and the other with the
handle of impulsion, he has merely his feet for acting upon the lever _n
o_, and as he has many other things to do, M. Heilmann has adapted
before him a system of two pedals, by which he executes with his feet a
series of operations no less delicate than those which he executes with
his hands.

The pedals P are moveable round the axis _p_, and carry cords _p´_ wound
in an opposite direction upon the pulleys P´; these pulleys are fixed
upon a moveable shaft P´´, supported upon one side by the prop E´, and
on the other in a piece K´ attached to the two great uprights of the
frame. In depressing the pedal P (now raised in the figure), the upper
part of the shaft P´´ will turn from the left to the right, and the
lever _n o_ will become inclined so as to carry the wheel O´ upon the
wheel M´, but at the same time the pedal which is now depressed will be
raised, because its cord will be forced to wind itself upon its pulley,
as much as the other cord has unwound itself; and thus the apparatus
will be ready to act in the opposite direction, when wanted.

_Disposition of the pincers._--The shaft L´ carries, at regular
intervals of a semi-diameter, the appendages _q q_ cast upon it, upon
which are fixed, by two bolts, the curved branches Q destined to bear
the whole mechanism of the pincers. When the pincers are opened by their
appropriate leverage, and the half of the needle, which is pointed at
each end, with the eye in the middle, enters the opening of its plate,
it gets lodged in an angular groove, which is less deep than the needle
is thick, so that when the pincers are closed, the upper jaw presses it
into the groove. In this way the needle is firmly held, although touched
in only three points of its circumference.

Suppose, now, that all the pincers are mounted and adjusted at their
proper distances upon their prismatic bar, forming the upper range of
the right carriage. For opening all the pincers there is a long plate of
iron, U, capable of turning upon its axis, and which extends from the
one end of the carriage to the other. This axis is carried by a kind of
forks which are bolted to the extremity of the branches Q. By turning
that axis the workman can open the pincers at pleasure, and they are
again closed by springs. This movement is performed by his feet acting
upon the pedals.

The threads get stretched in proportion as the carriage is run out, but
as this tension has no elastic play, inconveniences might ensue which
are prevented by adapting to the carriage a mechanism by means of which
all the threads are pressed at the same time by a weight susceptible of
graduation. A little beneath the prismatic bar, which carries the
pincers, we see in the figure, a shaft Y, going from one end of the
carriage to the other, and even a little beyond it; this shaft is
carried by pieces _y_ which are fixed to the arms Q, and in which it can
turn. At its left end it carries two small bars _y´_ and _w´_, and at
its right a single bar _y´_, and a counterweight (not visible in this
view); the ends of the two bars _y´_ are joined by an iron wire somewhat
stout and perfectly straight. When the carriage approaches the web, and
before the iron wire can touch it, the little bar _w_ presses against a
pin _w´_, which rests upon it, and tends to raise it more and more. In
what has preceded we have kept in view only the upper range of pincers
and needles, but there is an inferior range quite similar, as the figure
shows, at the lower ends of the arms Q. In conclusion, it should be
stated, that the operative does not follow slidingly with the pantograph
the trace of the design which is upon the tablet or the picture, but he
must stop the point of the style upon the point of the pattern into
which the needle should enter, then remove it, and put it down again
upon the point by which the needle ought to re-enter in coming from the
other side of the piece, and so on in succession. To facilitate this
kind of reading off, the pattern upon the tablet is composed of right
lines terminated by the points for the entrance and return of the
needle, so that the operative (usually a child) has continually under
her eyes the series of broken lines which must be followed by the
pantograph; if she happens to quit this path an instant, without having
left a mark of the point at which she had arrived, she is under the
necessity of looking at the piece to see what has been already
embroidered, and to find by this comparison the point at which she must
resume her work, so as not to leave a blank, or to repeat the same
stitch.

_Explanation of figure:_

A, lower cross bars, which unite the legs of the two ends of the frame.

_a_, the six feet of the front end of the frame.

_a´_, the six feet of the posterior end of the frame.

_a´´_, curved pieces which unite the cross bars A´´ to the uprights.

B´´, handle of the pantograph.

_b b´ b´´_, three of the angles of the pantograph.

_c_, point of the side _b b´´_ on which the point is fixed.

C´´, point of the pantograph.

D´´, cross bar in form of a gutter, which unites the upper parts of the
frame.

_d_, fixed point, round which the pantograph turns.

E, tablet upon which the pattern to be embroidered is put.

E´, support of that tablet.

_e_, cord attached at one end to the side _b c_ of the pantograph
passing over a guide pulley, and carrying a weight at the other end.

_e´_, iron rod by which the tablet E is joined to its support E´.

F F, uprights of the cloth-carrying frame.

F´ F´, horizontal sides of the same frame.

G, four roll beams.

G´´, the piece of cloth.

_g´´_, the strings, which serve to stretch the cloth laterally.


EMERALD. (_Emeraude_, Fr.; _Smaragd_, Germ.) Is a precious stone of a
beautiful green colour; valued next to diamond, and in the same rank as
oriental ruby and sapphire. It occurs in prisms with a regular hexagonal
base; sp. grav. 2·7; scratches quartz with difficulty; is scratched by
topaz; fusible at the blowpipe into a frothy bead; the precipitate
afforded by ammonia, from its solution, is soluble, in a great measure,
in carbonate of ammonia. Its analysis is given very variously by
different chemists. It contains about 14 per cent. of glucina, which is
its characteristic constituent; along with 68 of silica, 16 of alumina,
a very little lime and iron. The beautiful emerald of Peru is found in a
clay schist mixed with some calcareous matter. A stone of 4 grains
weight is said to be worth from 4_l._ to 5_l._; one of 8 grains, 10_l._;
one of 15 grains, being fine, is worth 60_l._; one of 24 grains fetched,
at the sale of M. de Drée’s cabinet, 2400 francs, or nearly 100_l._

The beryl is analogous in composition to the emerald, and is employed
(when of the common opaque kind, found near Limoges,) by chemists, for
procuring the earth glucina.


EMERY. This mineral was long regarded as an ore of iron; and was called
by Haüy _fer oxidé quartzifère_. It is very abundant in the island of
Naxos, at cape _Emeri_, whence it is imported in large quantities. It
occurs also in the islands of Jersey and Guernsey, at Almaden, in
Poland, Saxony, Sweden, Persia, &c. Its colour varies from red brown to
dark brown; its specific gravity is about 4·000; it is so hard as to
scratch quartz and many precious stones. By Mr. Tennant’s analysis, it
consists of alumina, 80; silica, 3; iron, 4. Another inferior kind
yielded 32 of iron, and only 50 of alumina.

The alumina of emery is believed to be aggregated to the same degree of
hardness as in corundum or adamantine spar; which is one of the hardest
minerals known. Emery is extensively employed for grinding metals,
glass, &c.; for which purpose it is reduced to powders of different
degrees of fineness by grinding and elutriation. When so treated, it is
sold under the name of flour of emery, or washed emery.


EMPYREUMA, means the offensive smell produced by fire applied to organic
matters, chiefly vegetable, in close vessels. Thus, empyreumatic vinegar
is obtained by distilling wood at a red heat, and empyreumatic oil from
many animal substances in the same way.


ENAMELS, (_Emaux_, Fr.; _Schmelzglas_, Germ.) are varieties of glass,
generally opaque and coloured, always formed by the combination of
different metallic oxides, to which certain fixed fusible salts are
added, such as the borates, fluates, and phosphates.

The simplest enamel, and the one which serves as a basis to most of the
others, is obtained by calcining first of all a mixture of lead and tin,
in proportions varying from 15 to 50 parts of tin for 100 of lead. The
middle term appears to be the most suitable for the greater number of
enamels; and this alloy has such an affinity for oxygen, that it may be
calcined with the greatest ease in a flat cast-iron pot, and at a
temperature not above a cherry red, provided the dose of tin is not too
great. The oxide is drawn off to the sides of the melted metal according
as it is generated, new pieces of the alloy being thrown in from time to
time, till enough of the powder be obtained. Great care ought to be
taken that no metallic particles be left in the oxide, and that the
calcining heat be as low as is barely sufficient; for a strong fire
frits the powder, and obstructs its subsequent comminution. The powder
when cold is ground in a proper mill, levigated with water, and
elutriated, as will be described under _Red lead_. In this state of
fineness and purity, it is called _calcine_, or flux, and it is mixed
with siliceous sand and some alkaline matter or sea-salt. The most
ordinary proportions are, 4 of sand, 1 of sea-salt, and 4 of calcine.
Chaptal states, that he has obtained a very fine product from 100 parts
of calcine, made by calcining equal parts of lead and tin, 100 parts of
ground flint, and 200 parts of pure subcarbonate of potash. In either
case, the mixture is put into a crucible, or laid simply on a stratum of
sand, quicklime spontaneously slacked, or wood-ashes, placed under a
pottery or porcelain kiln. This mass undergoes a semi-vitrification; or
even a complete fusion on its surface. It is this kind of frit which
serves as a radical to almost every enamel; and by varying the
proportions of the ingredient, more fusible, more opaque, or whiter
enamels are obtained. The first of these qualities depends on the
quantity of sand or flux, and the other two on that of the tin.

The sea-salt employed as a flux may be replaced either by salt of
tartar, by pure potash, or by soda; but each of these fluxes gives
peculiar qualities to the enamel.

Most authors who have written on the preparation of enamels, insist a
great deal on the necessity of selecting carefully the particular sand
that should enter into the composition of the frit, and they even affirm
that the purest is not the most suitable. Clouet states, in the 34th
volume of the _Annales de Chimie_, that the sand ought to contain at
least 1 part of talc for 3 of siliceous matter, otherwise the enamel
obtained is never very glassy, and that some wrinkled spots from
imperfect fusion are seen on its surface; and yet we find prescribed in
some old treatises, to make use of ground flints, fritted by means of
salt of tartar or some other flux. It would thence appear that the
presence of talc is of no use towards the fusibility of the silica, and
that its absence may be supplied by increasing the dose of the flux. In
all cases, however, we ought to beware of metallic oxides in the sand,
particularly those of iron and manganese, which most frequently occur,
and always injure the whiteness of the frit.

The ancients carried the art of enamelling to a very high perfection,
and we occasionally find beautiful specimens of their work, of which we
know neither the composition, nor the manner of applying it. Then, as at
present, each artist made a mystery of the means that succeeded best
with him, and thus a multitude of curious processes have been buried
with their authors. Another cause contributes powerfully to this sort of
declension in the arts. Among the vast number of recipes which have been
published for the formation of enamels, there are several in which
substances are mentioned that can no longer be procured, whether owing
to a change of denomination, or because the substances cannot now be
found in commerce, or because they are not of the same nature as of old.
Hence, in many cases, we find it impossible to obtain satisfactory
results. What we have now said renders it desirable that the operations
should be resumed anew, or upon new bases, and availing ourselves of all
the known chemical facts, we should employ in the production of enamels,
raw materials of the purest kind.

The Venetians are still in possession of the best enamel processes, and
they supply the French and other nations with the best kinds of enamel,
of every coloured shade.

Enamels are distinguished into transparent and opaque; in the former all
the elements have experienced an equal degree of liquefaction, and are
thus run into crystal glass, whilst in the others, some of their
elements have resisted the action of heat more, so that their particles
retain sufficient aggregation to prevent the transmission of light. This
effect is produced, particularly by the oxide of tin, as we shall
perceive in treating of white enamel.

The frits for enamels that are to be applied to metallic surfaces
require greater fusibility, and should therefore contain more flux; and
the sand used for these should be calcined beforehand with one-fourth
its weight of sea-salt; sometimes, indeed, metallic fluxes are added, as
minium or litharge. For some metallic colours, the oxides of lead are
very injurious, and in this case recourse must be had to other fluxes.
Clouet states that he has derived advantage from the following mixtures,
as bases for purples, blues, and some other delicate colours:--

Three parts of siliceous sand, one of chalk, and three of calcined
borax; or, three of glass (of broken crystal goblets), one of calcined
borax, one-fourth of a part of nitre, and one part of well washed
diaphoretic antimony. These compositions afford a very white enamel,
which accords perfectly well with blue.

It is obvious that the composition of this primary matter may be greatly
varied; but we should never lose sight of the essential quality of a
good enamel; which is, to acquire, at a moderate heat, sufficient
fluidity, to take a shining surface, without running too thin. It is not
complete fusion which is wanted; but a pasty state, of such a degree as
may give it, after cooling, the aspect of having suffered complete
liquefaction.

_Dead-white Enamel._--This requires greater nicety in the choice of its
materials than any other enamel, as it must be free from every species
of tint, and be perfectly white; hence the frit employed in this case
should be itself composed of perfectly pure ingredients. But a frit
should not be rejected hastily because it may be somewhat discoloured,
since this may depend on two causes; either on some metallic oxides, or
on fuliginous particles proceeding from vegetable or animal substances.
Now the latter impurities may be easily removed by means of a small
quantity of peroxide of manganese, which has the property of readily
parting with a portion of its oxygen, and of thus facilitating the
combustion, that is to say, the destruction of the colouring
carbonaceous matter. Manganese indeed possesses a colouring power itself
on glass, but only in its highest state of oxidizement, and when reduced
to the lower state, as is done by incombustible matters, it no longer
communicates colour to the enamel combinations. Hence the proportion of
manganese should never exceed what is just; for the surplus would cause
colour. Sometimes, indeed, it becomes necessary to give a little
manganese-colour, in order to obtain a more agreeable shade of white; as
a little azure blue is added to linens, to brighten or counteract the
dulness of their yellow tint.

A white enamel may be conveniently prepared also with a _calcine_
composed of two parts of tin and one of lead calcined together; of this
combined oxide, one part is melted with two parts of fine crystal and a
very little manganese, all previously ground together. When the fusion
is complete, the vitreous matter is to be poured into clear water, and
the frit is then dried, and melted anew. The pouring into water and
fusion are sometimes repeated 4 times, in order to secure a very uniform
combination. The crucible must be carefully screened from smoke and
flame. The smallest portions of oxide of iron or copper admitted into
this enamel will destroy its value.

Some practitioners recommend the use of washed diaphoretic antimony
(antimoniate of potash, from metallic antimony and nitre deflagrated
together) for white enamel; but this product cannot be added to any
preparation of lead or other metallic oxides; for it would tend rather
to tarnish the colour than to clear it up; and it can be used therefore
only with ordinary glass, or with saline fluxes. For three parts of
white glass (without lead) one part of washed diaphoretic antimony is to
be taken; the substances are well ground together, and fused in the
common way.

_Blue Enamel._--This fine colour is almost always obtained from the
oxide of cobalt or some of its combinations, and it produces it with
such intensity that only a very little can be used, lest the shade
should pass into black. The cobalt blue is so rich and lively that it
predominates in some measure over every other colour, and masks many so
that they can hardly be perceived; it is also most easily obtained. To
bring it out, however, in all its beauty, the other colours must be
removed as much as possible, and the cobalt itself should be tolerably
pure. This metal is associated in the best known ores with a
considerable number of foreign substances, as iron, arsenic, copper,
nickel, and sulphur, and it is difficult to separate them completely;
but for enamel blues, the oxide of cobalt does not require to be
perfectly free from all foreign metals; the iron, nickel, and copper
being most prejudicial, should be carefully eliminated. This object may
be most easily attained by dissolving the ore in nitric acid,
evaporating the solution to a syrupy consistence, to expel the excess of
acid, and separate a portion of arsenic. It is now diluted with water,
and solution of carbonate of soda is dropped slowly into it with brisk
agitation, till the precipitate, which is at first of a whitish gray,
begins to turn of a rose-red. Whenever this colour appears, the whole
must be thrown on a filter, and the liquid which passes through must be
treated with more of the carbonate of soda, in order to obtain the
arseniate of cobalt, which is nearly pure. Since arsenic acid and its
derivatives are not capable of communicating colour themselves, and as
they moreover are volatile, they cannot impair the beauty of the blue,
and hence this preparation affords it in great perfection.

Metallic fluxes are not the most suitable for this colour; because they
always communicate a tint of greater or less force, which never fails to
injure the purity of the blue. Nitre is a useful addition, as it keeps
the oxide at the maximum of oxidation, in which state it produces the
richest colour.

_Yellow Enamel._--There are many processes for making this colour in
enamel; but it is somewhat difficult to fix, and it is rarely obtained
of an uniform and fine tint. It may be produced directly with some
preparations of silver, as the phosphate or sulphate; but this method
does not always succeed, for too strong a heat or powerful fluxes
readily destroy it, and nitre is particularly prejudicial. This
uncertainty of success with the salts of silver causes them to be seldom
employed; and oxides of lead and antimony are therefore preferred, which
afford a fine yellow when combined with some oxides that are refractory
enough to prevent their complete vitrification. One part of white oxide
of antimony may be taken with from one to three parts of white lead, one
of alum, and one of sal-ammoniac. Each of these substances is to be
pulverized, and then all are to be exactly mixed, and exposed to a heat
adequate to decompose the sal-ammoniac. This operation is judged to be
finished when the yellow colour is well brought out. There is produced
here a combination quite analogous to that known under the name of
Naples yellow.

Other shades of yellow may be procured either with the oxide of lead
alone, or by adding to it a little red oxide of iron; the tints varying
with the proportion of the latter.

Clouet says, in his memoir on enamels, that a fine yellow is obtained
with pure oxide of silver, and that it is merely necessary to spread a
thin coat of it on the spot to be coloured. The piece is then exposed to
a moderate heat, and withdrawn as soon as this has reached the proper
point. The thin film of metallic silver revived on the surface being
removed, the place under it will be found tinged of a fine yellow, of
hardly any thickness. As the pellicle of silver has to be removed which
covers the colour, it is requisite to avoid fixing this film with
fluxes; and it ought therefore to be applied after the fusion of the
rest. The yellows require in general little flux, and they answer better
with one of a metallic nature.

_Green Enamel._--It is known that a green colour may be produced by a
mixture of yellow and blue; but recourse is seldom had to this practice
for enamels, as they can be obtained almost always directly with the
oxide of copper; or still better with the oxide of chrome, which has the
advantage of resisting a strong heat.

Chemists describe two oxides of copper, the protoxide, of an orange red
colour, which communicates its colour to enamels, but it is difficult to
fix; the deutoxide is blue in the state of hydrate, but blackish-brown
when dry, and it colours green all the vitreous combinations into which
it enters. This oxide requires, at most, one or two proportions of flux,
either saline or metallic, to enter into complete fusion; but a much
smaller dose is commonly taken, and a little oxide of iron is
introduced. To four pounds of frit, for instance, two ounces of oxide of
copper and 48 grains of red oxide of iron are used; and the ordinary
measures are pursued for making very homogeneous enamel.

The green produced by the oxide of chrome is much more solid; it is not
affected by a powerful fire, but it is not always of a fine shade. It
generally inclines too much to the dead-leaf yellow, which depends on
the degree of oxygenation of the chrome.

_Red Enamel._--We have just stated, that protoxide of copper afforded a
fine colour when it could be fixed, a result difficult to obtain on
account of the fugitive nature of this oxide; slight variations of
temperature enabling it to absorb more oxygen. The proper point of
fusion must be seized, for taking it from the fire whenever the desired
colour is brought out. Indeed, when a high temperature has produced
peroxidizement, this may be corrected by adding some combustible matter,
as charcoal, tallow, tartar, &c. The copper then returns to its minimum
of oxidizement, and the red colour which had vanished, reappears. It is
possible, in this way, and by pushing the heat a little, to accomplish
the complete reduction of a part of the oxide; and the particles of
metallic copper thereby disseminated in a reddish ground, give this
enamel the aspect of the stone called _avanturine_. The surest and
easiest method of procuring protoxide of copper is to boil a solution of
equal parts of sugar, and sulphate or rather acetate of copper, in four
parts of water. The sugar takes possession of a portion of the oxygen of
the cupreous oxide, and reduces it to the protoxide; when it may be
precipitated in the form of a granular powder of a brilliant red. After
about two hours of moderate ebullition, the liquid is set aside to
settle, decanted off the precipitate, which is washed and dried.

This pure oxide, properly employed by itself, furnishes a red which vies
with the finest carmine, and by its means every tint may be obtained
from red to orange, by adding a greater or smaller quantity of peroxide
of iron.

The preparations of gold, and particularly the oxide and purple of
Cassius, are likewise employed, with advantage, to colour enamel red,
and this composition resists a powerful fire tolerably well. For some
time back, solutions of gold, silver, and platinum have been used with
success instead of their oxides; and, in this way, a more intimate
mixture may be procured, and, consequently, more homogeneous tints.

_Black Enamel._--Black enamels are made with peroxide of manganese or
protoxide of iron; to which more depth of colour is given with a little
cobalt. Clay alone, melted with about a third of its weight of protoxide
of iron, gives, according to Clouet, a fine black enamel.

_Violet Enamel._--The peroxide of manganese in small quantity by itself
furnishes, with saline or alkaline fluxes, an enamel of a very fine
violet hue; and variations of shade are easily had by modifying the
proportions of the elements of the coloured frit. The great point is to
maintain the manganese in a state of peroxidation, and consequently to
beware of placing the enamel in contact with any substance attractive of
oxygen.

Such are the principal coloured enamels hitherto obtained by means of
metallic oxides; but since the number of these oxides is increasing
every day, it is to be wished that new trials be made with such as have
not yet been employed. From such researches some interesting results
would unquestionably be derived.

_Of painting on Enamel._--Enamelling is only done on gold and copper;
for silver swells up, and causes blisters and holes in the coat of
enamel. All enamel paintings are, in fact, done on copper or gold.

The goldsmith prepares the plate that is to be painted upon. The gold
should be 22 carats fine: if purer, it would not be sufficiently stiff;
if coarser, it would be subject to melt; and its alloy should be half
white and half red, that is, half silver and half copper; whereby the
enamel with which it is covered will be less disposed to turn green,
than if the alloy were entirely copper.

The workman must reserve for the edge of the plate a small fillet, which
he calls the _border_. This ledge serves to retain the enamel, and
hinders it from falling off when applied and pressed on with a spatula.
When the plate is not to be counter-enamelled, it should be charged with
less enamel, as, when exposed to heat, the enamel draws up the gold to
itself, and makes the piece convex. When the enamel is not to cover the
whole plate, it becomes necessary to prepare a lodgement for it. With
this view, all the outlines of the figure are traced on the plate with a
black-lead pencil, after which recourse is had to the graver.

The whole space enclosed by the outlines must be hollowed out in
_bas-relief_, of a depth equal to the height of the fillet, had the
plate been entirely enamelled. This sinking of the surface must be done
with a flat graver as equally as possible; for if there be an eminence,
the enamel would be weaker at that point, and the green would appear.
Some artists hatch the bottom of the hollow with close lines, which
cross each other in all directions; and others make lines or scratches
with the end of a file broken off square. The hatchings or scratches lay
hold of the enamel, which might otherwise separate from the plate. After
this operation, the plate is cleansed by boiling it in an alkaline ley,
and it is washed first with a little weak vinegar, and then with clear
water.

The plate thus prepared is to be covered with a coat of white enamel,
which is done by bruising a piece of enamel in an agate or porcelain
mortar to a coarse powder like sand, washing it well with water, and
applying it in the hollow part in its moist state. The plate may
meanwhile be held in an ordinary forceps. The enamel powder is spread
with a spatula. For condensing the enamel powder, the edges of the plate
are struck upon with this spatula.

[Illustration: 375]

Whenever the piece is dry, it is placed on a slip of sheet iron
perforated with several small holes, see _fig._ 375., which is laid on
hot cinders; and it is left there until it ceases to steam. It must be
kept hot till it goes to the fire; for were it allowed to cool it would
become necessary to heat it again very gradually at the mouth of the
furnace of fusion, to prevent the enamel from decrepitating and flying
off.

[Illustration: 376 377]

Before describing the manner of exposing the piece to the fire, we must
explain the construction of the furnace. It is square, and is shewn in
front elevation in _fig._ 376. It consists of two pieces, the lower part
A, or the body of the furnace, and the upper part B, or the capital,
which is laid on the lower part as is shewn in _fig._ 377., where these
two parts are separately represented. The furnace is made of good
fire-clay, moderately baked, and resembles very closely the assay or
cupellation furnace. Its inside dimensions are 9 inches in width; 13
inches in height in the body, and 9 in the capital. Its general
thickness is 2 inches.

The capital has an aperture or door C, _fig._ 376., which is closed by a
fire-brick stopper _m_, when the fire is to be made active. By this door
fuel is supplied.

The body of the furnace has likewise a door D, which reaches down to the
projecting shelf E, called the bib (_mentonnière_), whose prominence is
seen at E, _fig._ 376. This shelf is supported and secured by the two
brackets F, F; the whole being earthenware. The height of the door D, is
abridged by a peculiar fire-brick G, which not only covers the whole
projection of the shelf E, but enters within the opening of the door D,
filling its breadth, and advancing into the same plane with the inner
surface of the furnace. This plate is called the hearth; its purpose
will appear presently; it may be taken out and replaced at pleasure, by
laying hold of the handle in its front.

Below the shelf E, a square hole, H, is seen, which serves for admitting
air, and for extracting the ashes. Similar holes are left upon each side
of the furnace, as is shown in the ground plan of the base, _fig._ 377.,
at H H H.

[Illustration: 378 379 380]

On a level with the shelf, in the interior of the furnace, a thin
fire-tile I rests, perforated with numerous small holes. This is the
grate represented in a ground view in _fig._ 375. _Fig._ 378, 379, 380.
represent, under different aspects, the muffle. _Fig._ 377. shows the
elevation of its further end; _fig._ 379. its sides; and _fig._ 380. its
front part. At J, _fig._ 377. the muffle is seen in its place in the
furnace, resting on two bars of iron, or, still better, on ledges of
fire-clay, supported on brackets attached to the lateral sides of the
furnace. The muffle is made of earthenware, and as thin as possible. The
fuel consists of dry beech-wood, or oaken branches, about an inch in
diameter, cut to the length of 9 inches, in order to be laid in
horizontal strata within the furnace, one row only being placed above
the muffle. When the muffle has attained to a white-red heat, the sheet
iron tray, bearing its enamel plate, is to be introduced with a pair of
pincers into the front of the muffle, and gradually advanced towards its
further end. The mouth of the muffle is to be then closed with two
pieces of charcoal only, between which the artist may see the progress
of the operation. Whenever the enamel begins to flow, the tray must be
turned round on its base to ensure equality of temperature; and as soon
as the whole surface is melted, the tray must be withdrawn with its
plate, but slowly, lest the vitreous matter be cracked by sudden
refrigeration.

The enamel plate, when cold, is to be washed in very dilute nitric acid,
and afterwards in cold water, and a second coat of granular enamel paste
is to be applied, with the requisite precautions. This, being passed
through the fire, is to be treated in the same way a third time, when
the process will be found complete. Should any chinks happen to the
enamel coat, they must be widened with a graver, and the space being
filled with ground enamel, is to be repaired in the muffle. The plate,
covered with a pure white enamel, requires always to be polished and
smoothed with sandstone and water, particularly if the article have a
plane surface; and it is then finally glazed at the fire.

The painting operation now follows. The artist prepares his enamel
colours by pounding them in an agate mortar, with a pestle of agate, and
grinding them on an agate slab, with oil of lavender, rendered viscid by
exposure to the sun in a shallow vessel, loosely covered with gauze or
glass. The grinding of two drachms of enamel pigment into an impalpable
powder, will occupy a labourer a whole day. The painter should have
alongside of him a stove in which a moderate fire is kept up, for drying
his work whenever the figures are finished. It is then passed through
the muffle.

_Enamelling at the Lamp._--The art of the lamp enameller is one of the
most agreeable and amusing that we know. There is hardly a subject in
enamel which may not be executed by the lamp-flame in very little time,
and more or less perfectly, according to the dexterity of the artist,
and his acquaintance with the principles of modelling.

In working at the lamp, tubes and rods of glass and enamel must be
provided, of all sizes and colours.

[Illustration: 373]

The enamelling table is represented in _fig._ 373., round which several
workmen, with their lamps, may be placed, while the large double bellows
D below is set a-blowing by a treadle moved with the foot. The flame of
the lamp, when thus impelled by a powerful jet of air, acquires
surprising intensity. The bent nozzles or tubes A A A A, are made of
glass, and are drawn to points modified to the purpose of the enameller.

[Illustration: 374]

_Fig._ 374. shows, in perspective, the lamp A of the enameller standing
in its cistern B; the blowpipe C is seen projecting its flame obliquely
upwards. The blowpipe is adjustable in an elastic cork D, which fills up
exactly the hole of the table into which it enters. When only one person
is to work at a table provided with several lamps, he sits down at the
same side with the pedal of the bellows; he takes out the other
blowpipes, and plugs the holes in the table with solid corks.

The lamp is made of copper or tin-plate, the wick of cotton threads, and
either tallow or oil may be used. Between the lamp and the workman a
small board or sheet of white iron B, called the screen, is interposed
to protect his eyes from the glare of light. The screen is fastened to
the table by a wooden stem, and it throws its shadow on his face.

The enamelling workshop ought to admit little or no daylight, otherwise
the artist, not perceiving his flame distinctly, would be apt to commit
mistakes.

It is impossible to describe all the manipulations of this ingenious
art, over which taste and dexterity so entirely preside. But we may give
an example. Suppose the enameller wishes to make a swan. He takes a tube
of white enamel, seals one of its ends hermetically at his lamp, and
while the matter is sufficiently hot, he blows on it a minikin flask,
resembling the body of the bird; he draws out, and gracefully bends the
neck; he shapes the head, the beak, and the tail; then, with slender
enamel rods of a proper colour, he makes the eyes; he next opens up the
beak with pointed scissors; he forms the wings and the legs; finally
attaching the toes, the bird stands complete.

The enameller also makes artificial eyes for human beings, imitating so
perfectly the colours of the sound eye of any individual, as to render
it difficult to discover that he has a blind and a seeing one.

It is difficult to make large articles at the blowpipe; those which
surpass 5 or 6 inches become nearly unmanageable by the most expert
workmen.


EPSOM SALTS. Sulphate of Magnesia.


EQUIVALENTS, CHEMICAL. (_Stöchiometrie_, Germ.) This expression was
first employed by Dr. Wollaston, to denote the primary proportions in
which the various chemical bodies reciprocally combine; the numbers
representing these proportions being referred to one standard substance
of general interest, such as oxygen or hydrogen reckoned unity, or
1,000. Dr. Dalton, who is the true author of the grand discovery of
definite, and multiple chemical ratios, calls these equivalent numbers
_atomic weights_, when reduced to their lowest terms, either hydrogen or
oxygen being the radix of the scale. Though it belongs to a chemical
work, to discuss the principles and develope the applications of the
Atomic Theory, I shall be careful, upon all proper occasions, to point
out the vast advantages which the chemical manufacturer may derive from
it, and to show how much he may economize and improve his actual
processes by its means. See ELEMENT.


ESSENCES, are either ethereous oils, in which all the fragrance of
vegetable products reside; or the same combined and diluted with
alcohol. See OILS, ETHEREOUS.


ESSENCE D’ORIENT, the name of a pearly looking matter procured from the
blay or bleak, a fish of the genus _cyprinus_. This substance, which is
found principally at the base of the scales, is used in the manufacture
of artificial pearls. A large quantity of the scales being scraped into
water in a tub, are there rubbed between the hands to separate the
shining stuff, which subsides on repose. The first water being decanted,
more is added with agitation till the essence is thoroughly washed from
all impurities; when the whole is thrown upon a sieve; the substance
passes through, but the scales are retained. The water being decanted
off, the essence is procured in a viscid state, of a bluish white
colour, and a pearly aspect. The intestines of the same fish are also
covered with this beautiful glistening matter. Several other fish yield
it, but in smaller proportion. When well prepared, it presents exactly
the appearance and reflections of the real pearls, or the finest mother
of pearl; properties which are probably owing to the interposition of
some portions of this same substance, between the laminæ of these shelly
concretions. Its chemical nature has not been investigated; it putrefies
readily when kept moist, an accident which may however be counteracted
by water of ammonia. See PEARLS.


ETCHING _Varnish_. (_Aetzgrund-Deckfirniss_, Germ.) Though the practice
of this elegant art does not come within the scope of our Dictionary,
the preparation of the varnishes, and of the biting menstrua which it
employs, legitimately does.

The varnish of Mr. Lawrence, an English artist resident in Paris, is
made as follows: Take of virgin wax and asphaltum, each two ounces, of
black pitch and burgundy-pitch each half an ounce. Melt the wax and
pitch in a new earthenware glazed pot, and add to them, by degrees, the
asphaltum, finely powdered. Let the whole boil till such time as that,
taking a drop upon a plate, it will break when it is cold, on bending it
double two or three times betwixt the fingers. The varnish, being then
enough boiled, must be taken off the fire, and after it cools a little,
must be poured into warm water that it may work the more easily with the
hands, so as to be formed into balls, which must be kneaded, and put
into a piece of taffety for use.

Care must be taken, first, that the fire be not too violent, for fear of
burning the ingredients, a slight simmering being sufficient; secondly,
that whilst the asphaltum is putting in, and even after it is mixed with
the ingredients, they should be stirred continually with the spatula;
and, thirdly, that the water into which this composition is thrown
should be nearly of the same degree of warmth with it, in order to
prevent a kind of cracking that happens when the water is too cold.

The varnish ought always to be made harder in summer than in winter, and
it will become so if it be suffered to boil longer, or if a greater
proportion of the asphaltum or brown rosin be used. The experiment
above mentioned, of the drop suffered to cool, will determine the degree
of hardness or softness that may be suitable to the season when it is
used.

Preparation of the hard varnish used by Callot, commonly called the
Florence Varnish:--Take four ounces of fat oil very clear, and made of
good linseed oil, like that used by painters; heat it in a clean pot of
glazed earthenware, and afterwards put to it four ounces of mastick well
powdered, and stir the mixture briskly till the whole be well melted,
then pass the mass through a piece of fine linen into a glass bottle
with a long neck, that can be stopped very securely; and keep it for the
use that will be explained below.

Method of applying the soft varnish to the plate, and of blackening
it.--The plate being well polished and burnished, as also cleansed from
all greasiness by chalk or Spanish white, fix a hand-vice on the edge of
the plate where no work is intended to be, to serve as a handle for
managing it when warm; then put it upon a chafing dish, in which there
is a moderate fire, and cover the whole plate equally with a thin coat
of the varnish; and whilst the plate is warm, and the varnish upon it in
a fluid state, beat every part of the varnish gently with a small ball
or dauber made of cotton tied up in taffety, which operation smooths and
distributes the varnish equally over the plate.

When the plate is thus uniformly and thinly covered with the varnish, it
must be blackened by a piece of flambeau, or of a large candle which
affords a copious smoke; sometimes two or even four such candles are
used together for the sake of dispatch, that the varnish may not grow
cold, which if it does during the operation, the plate must be heated
again, that it may be in a melted state when that operation is
performed; but great care must be taken not to burn it, which when it
happens may be easily perceived by the varnish appearing burnt and
losing its gloss.

The menstruum used and recommended by Turrell, an eminent London artist,
for etching upon steel, was prepared as follows:--

  Take Pyrolignous acid 4 parts by measure,
       Alcohol          1 part, mix, and add
       Nitric acid      1 part.

This mixed liquor is to be applied from 1-1/2 to 15 minutes, according
to the depth desired. The nitric acid was employed of the strength of
1·28--the double aquafortis of the shops.

The _eau forte_ or menstruum for copper, used by Callot, as also by
Piranesi, with a slight modification, is prepared, with

   8 parts of strong French vinegar,
   4 parts of verdigris,
   4 ditto sea salt,
   4 ditto sal ammoniac,
   1 ditto alum,
  16 ditto water.

The solid substances are to be well ground, dissolved in the vinegar,
and diluted with the water; the mixture is now to be boiled for a
moment, and then set aside to cool. This menstruum is applied to the
washed, dried, and varnished plate, after it has suffered the ordinary
action of aquafortis, in order to deepen and finish the delicate
touches. It is at present called the _eau forte à passer_.


ETHER, is the name of a class of very light, volatile, inflammable, and
fragrant spirituous liquids, obtained by distilling in a glass retort, a
mixture of alcohol with almost any strong acid. Every acid modifies the
result, in a certain degree, whence several varieties of ether are
produced. The only one of commercial importance is sulphuric ether,
which was first made known under the name of _sweet oil of vitriol_, in
1540, by the receipt of Walterus Cordus. Froberus, 190 years after that
date, directed the attention of chemists afresh to this substance, under
the new denomination of _ether_.

There are two methods of preparing it; by the first, the whole quantity
of acid and alcohol are mixed at once, and directly subjected to
distillation; by the second, the alcohol is admitted, in a slender
streamlet, into a body of acid previously mixed with a little alcohol,
and heated to 220° Fahr.

1. Mix equal weights of alcohol at spec. grav. 0·830, and sulphuric acid
at 1·842, by introducing the former into a large tubulated retort,
giving it a whirling motion, so that the alcohol may revolve round a
central conical cavity. Into this species of whirlpool the acid is to be
slowly poured. The mixture, which becomes warm, is to be forthwith
distilled by attaching a spacious receiver to the retort, and applying
the heat of a sand-bath. The formation of ether takes place only at a
certain temperature. If the contents of the retort be allowed to cool,
and be then slowly heated in a water bath, alcohol alone will come over
for some time without ether, till the mixture acquires the proper
degree of heat. The first receiver should be a globe, with a tube
proceeding from its bottom, into a second receiver, of a cylindric
shape, surrounded with ice-cold water. The joints must be well secured
by lutes, after the expanded air has been allowed to escape. The liquid
in the retort should be kept in a steady state of bullition. The ether,
as long as it is produced, condenses in the balloon and neck of the
receiver in striæ; when these disappear the process is completed. The
retort must now be removed from the sand; otherwise it would become
filled with white fumes containing sulphurous acid, and denser striæ
would flow over, which would contaminate the light product with a liquid
called sweet oil of wine.

The theory of etherification demonstrates that when strong sulphuric
acid is mixed with alcohol, there is formed, on the one hand, a more
aqueous sulphuric acid, and, on the other, sulphovinic acid. When this
mixture is made to boil, the sulphovinic acid is decomposed, its
dihydrate of carbon combines with the alcohol, and constitutes ether;
while the proportion of sulphovinic acid progressively diminishes. Mr.
Hennell, of the Apothecaries’ Hall, first explained these phenomena, and
he was confirmed in his views by the interesting researches of Serullas.
The acid left in the retort is usually of a black colour, and may be
employed to convert into ether half as much alcohol again; an experiment
which may be repeated several times in succession.

The most profitable way of manufacturing ether has been pointed out by
Boullay. It consists in letting the alcohol drop in a slender stream
into the acid, previously heated to the etherifying temperature. If the
acid in this case were concentrated to 1·846, the reaction would be too
violent, and the ether would be transformed into bicarburetted hydrogen
(dihydrate of carbon.) It is therefore necessary to dilute the acid down
to the density of 1·780; but this dilution may be preferably effected
with alcohol instead of water, by mixing three parts of the strongest
acid with 2 of alcohol, specific gravity 0·830, and distilling off a
portion of the ether thereby generated; after which the stream of
alcohol is to be introduced into the tubulure of the retort through a
small glass tube plunged into the mixture; this tube being the
prolongation of a metallic syphon, whose shorter leg dips into a bottle
filled with the alcohol. The longer leg is furnished with a stop-cock,
for regulating at pleasure the alcoholic streamlet. The distilled
vapours should be transmitted through a worm of pure tin surrounded by
cold water, and the condensed fluid received in a glass bottle. The
quantity of alcohol which can be thus converted into ether by a given
weight of sulphuric acid, has not hitherto been accurately determined;
but it is at least double. In operating in this way, neither sulphurous
acid, nor sweet oil of wine is generated, while the residuary liquid in
the retort continues limpid and of a merely brownish yellow colour. No
sulphovinic acid is formed, and according to the experiments of Geiger,
the proportion of ether approaches to what theory shows to be the
maximum amount. In fact 57 parts of alcohol of 0·83 sp. grav. being
equivalent to 46·8 parts of anhydrous alcohol, yield according to
Geiger, 33-1/2 parts of ether; and by calculation, they should yield
37-1/4.

The ether of the first distillation is never pure, but always contains a
certain quantity of alcohol. The density of that product is usually
0·78, and if prepared by the first of the above methods, contains
besides alcohol, pretty frequently sulphurous acid, and sweet oil of
wine, impurities from which it must be freed. Being agitated with its
bulk of milk of lime, both the acid and the alcohol are removed at the
same time; and if it be then decanted and agitated, first with its bulk
of water, next decanted into a retort containing chloride of calcium in
coarse powder and distilled, one third of perfectly pure ether may be
drawn over. Gay Lussac recommends to agitate the ether, first with twice
its volume of water, to mix it, and leave it in contact with powdered
unslaked lime for 12 or 14 hours, and then to distil off one third of
pure ether. The remaining two thirds consist of ether containing a
little alcohol. If in preparing ether by Boullay’s method, the alcohol
be too rapidly introduced, much of this liquid will come over unchanged.
If in this state the ether be shaken with water, a notable quantity of
it will be absorbed, because weak alcohol dissolves it very copiously.
The above product should therefore be re-distilled, and the first half
that comes over may be considered as ether, and treated with water and
lime. The other half must be exposed afresh to the action of sulphuric
acid.

Pure ether possesses the following properties. It is limpid, of spec.
grav. 0·713, or 0·715 at 60°; has a peculiar penetrating strong smell; a
taste at first acrid, burning, sweetish, and finally cooling. It has
neither an acid nor alkaline reaction; is a non-conductor of
electricity, and refracts light strongly. It is very volatile, boiling
at 96° or 97° F., and produces by its evaporation a great degree of
cold. At the temperature of 62·4, the vapour of ether balances a column
of mercury 15 inches high, or half the weight of the atmosphere. When
ether is cooled to -24° F. it begins to crystallize in brilliant white
plates, and at -47° it becomes a white crystalline solid. When vapour of
ether is made to traverse a red hot porcelain tube, it deposits within
it one half per cent. of charcoal, and there are condensed in the
receiver one and two thirds per cent. of a brown oil, partly in
crystalline scales, and partly viscid. The crystalline portion is
soluble in alcohol, but the viscid only in ether. The remainder of the
decomposed ether consists of bi-carburetted hydrogen gas, tetrahydric
carburet, carbonic oxide gas, and one per cent. at most of gaseous
carbonic acid.

Ether takes fire readily, even at some distance from a flame, and it
should not therefore be poured from one vessel to another in the
neighbourhood of a lighted candle. It may be likewise set on fire by the
electric spark. It burns all away with a bright fuliginous flame. When
the vapour of ether is mixed with 10 times its volume of oxygen, it
burns with a violent explosion, absorbs 6 times its bulk of oxygen, and
produces 4 times its volume of carbonic acid gas.

Ether alters gradually with contact of air; absorbing oxygen, and
progressively changing into acetic acid and water. This conversion takes
place very rapidly when the ether is boiled in an open vessel, while the
acid enters into a new combination forming acetic ether. Ether should be
preserved in bottles perfectly full and well corked, and kept in a cool
place, otherwise it becomes sour, and is destroyed. It contains in this
state 15 per cent. of its bulk of azote, but no oxygen gas, as this has
combined with its elements. Ether is composed of oxygen 21·24; hydrogen
13·85; carbon 65·05. This composition may be represented by 1 prime
equivalent of water, and 4 primes of bi-carburetted hydrogen gas; in
other words, ether contains for 1 prime of water, once as much olefiant
gas as alcohol, and its prime equivalent is therefore 468·15 to oxygen
100. By my analysis, as published in the Phil. Trans. for 1822, ether is
composed of oxygen 27·10; hydrogen 13·3; and carbon 59·6 in 100 parts.
The density of my ether was 0·700. One volume of vapour of ether
consists of one volume of aqueous vapour and two volumes of olefiant gas
(bi-carburetted hydrogen,) while alcohol consists of two volumes of
each.


ETHER, ACETIC, is used to flavour silent corn spirits in making
imitation brandy. It may be prepared by mixing 20 parts of acetate of
lead, 10 parts of alcohol, and 11-1/2 of concentrated sulphuric acid; or
16 of the anhydrous acetate, 5 of the acid, and 4-1/2 of absolute
alcohol; distilling the mixture in a glass retort into a very cold
receiver, agitating along with weak potash lye the liquor which comes
over, decanting the supernatant ether, and rectifying it by
re-distillation over magnesia and ground charcoal.

Acetic ether is a colourless liquid of a fragrant smell and pungent
taste, of spec. grav. 0·866 at 45° F., boiling at 166° F, burning with a
yellowish flame, and disengaging fumes of acetic acid. It is soluble in
8 parts of water.

Acetic ether may be economically made with 3 parts of acetate of potash,
3 of very strong alcohol, and 2 of the strongest sulphuric acid,
distilled together. The first product must be re-distilled along with
one fifth of its weight of sulphuric acid; as much ether will be
obtained as there was alcohol employed.


ETHIOPS, is the absurd name given by the alchemists to certain black
metallic preparations. Martial ethiops was the black oxide of iron;
mineral ethiops, the black sulphuret of mercury; and ethiops _per se_,
the black oxide of mercury.


EVAPORATION, (Eng. and Fr.; _Abdampfen_; _Abdunsten_, Germ.) is the
process by which any substance is converted into, and carried off in,
vapour. Though ice, camphor, and many other solids evaporate readily in
dry air, I shall consider, at present, merely the vaporization of water
by heat artificially applied.

The vapour of water is an elastic fluid, whose tension and density
depend upon the temperature of the water with which it is in contact.
Thus the vapour rising from water heated to 165° F. possesses an elastic
force capable of supporting a column of mercury 10·8 high; and its
density is such that 80 cubic feet of such vapour contain one pound
weight of water; whereas 32-1/2 cubic feet of steam of the density
corresponding to a temperature of 212° and a pressure of 30 inches of
mercury, weigh one pound. When the temperature of the water is given,
the elasticity and specific gravity of the vapour emitted by it, may be
found.

Since the vapour rises from the water only in virtue of the elasticity
due to its gaseous nature, it is obvious that no more can be produced,
unless what is already incumbent upon the liquid have its tension
abated, or be withdrawn by some means. Suppose the temperature of the
water to be midway between freezing and boiling, viz. 122° Fahr., as
also that of the air in contact with it, to be the same but replete with
moisture, so that its interstitial spaces are filled with vapour of
corresponding elasticity and specific gravity with that given off by the
water, it is certain that no fresh formation of vapour can take place in
these circumstances. But the moment a portion of vapour is allowed to
escape, or is drawn off by condensation to another vessel, an equivalent
portion of vapour will be immediately exhaled from the water.

The pressure of the air and of other vapours upon the surface of water
in an open vessel, does not prevent evaporation of the liquid; it merely
retards its progress. Experience shows that the space filled with an
elastic fluid, as air or other gaseous body, is capable of receiving as
much aqueous vapour as if it were vacuous, only the repletion of that
space with the vapour proceeds more slowly in the former predicament
than in the latter, but in both cases it arrives eventually at the same
pitch. Dr. Dalton has very ingeniously proved, that the particles of
aeriform bodies present no permanent obstacle to the introduction of a
gaseous atmosphere of another kind among them, but merely obstruct its
diffusion momentarily, as if by a species of friction. Hence, exhalation
at atmospheric temperatures is promoted by the mechanical diffusion of
the vapours through the air with ventilating fans or chimney draughts;
though under brisk ebullition, the force of the steam readily overcomes
that mechanical obstruction.

The quantities of water evaporated under different temperatures in like
times, are proportional to the elasticities of the steam corresponding
to these temperatures. A vessel of boiling water exposing a square foot
of surface to the fire, evaporates 725 grains in the minute; the
elasticity of the vapour is equivalent to 30 inches of mercury. To find
the quantity that would be evaporated from the same surface per minute
at a heat of 88° F. At this temperature the steam incumbent upon water
is capable of supporting 1·28 inch of mercury; whence the rule of
proportion is 30 : 1·28 ∷ 725 : 30·93; showing that about 31 grains of
water would be evaporated in the minute. If the air contains already
some aqueous vapour, as it commonly does, then the quantity of
evaporation will be proportional to the difference between the elastic
force of that vapour, and what rises from the water.

Suppose the air to be in the hygrometric state denoted by 0·38 of an
inch of mercury, then the above formula will become: 30 : 1·28 - 0·38 ∷
725 : 21·41; showing that not more than 21-1/2 grains would be
evaporated per minute under these circumstances.

The elastic tension of the atmospheric vapour is readily ascertained by
the old experiment of Le Roi, which consists in filling a glass cylinder
(a narrow tumbler for example) with cool spring water, and noting its
temperature at the instant it becomes so warm that dew ceases to be
deposited upon it. This temperature is that which corresponds to the
elastic tension of the atmospheric vapour. See VAPOUR, Table of.

Whenever the elasticity of the vapour, corresponding to the temperature
of the water, is greater than the atmospheric pressure, the evaporation
will take place not only from its surface, but from every point in its
interior; the liquid particles throughout the mass assuming the gaseous
form, as rapidly as they are actuated by the caloric, which subverts the
hydrostatic equilibrium among them, to constitute the phenomena of
ebullition. This turbulent vaporization takes place at any temperature,
even down to the freezing point, provided the pneumatic pressure be
removed from the liquid by the air pump, or any other means. Ebullition
always accelerates evaporation, as it serves to carry off the aqueous
particles not simply from the surface, but from the whole body of the
water.

The vapours, exhaled from a liquid at any temperature, contain more heat
than the fluid from which they spring; and they cease to form whenever
the supply of heat into the liquid is stopped. Any volume of water
requires for its conversion into vapour _five and a half times_ as much
heat as is sufficient to heat it from the freezing to the boiling
temperature. The heat, in the former case, seems to be absorbed, being
inappreciable by the thermometer; for steam is no hotter than the
boiling water from which it rises. It has been therefore called _latent
heat_; in contradistinction to that perceived by the touch and measured
by the thermometer, which is called _sensible heat_. The quantity of
heat absorbed by one volume of water in its conversion into steam, is
about 1000° Fahr.; it would be adequate to heat 1000 volumes of water,
one degree of the same scale; or to raise one volume of boiling water,
confined in a non-conducting vessel, to 1180°. Were the vessel charged
with water so heated, opened, it would be instantaneously emptied by
vaporization, since the whole caloric equivalent to its constitution as
steam, is present. When, upon the other hand, steam is condensed by
contact with cold substances, so much heat is set free as is capable of
heating five and a half times its weight of water, from 32° to 212° F.
If the supply of heat to a copper be uniform, five hours and a half will
be required to drive off its water in steam, provided one hour was taken
in heating the water, from the freezing to the boiling pitch, under the
atmospherical pressure.

Equal weights of vapour of any temperature contain equal quantities of
heat; for example, the vapour exhaled from one pound of water, at 77°
F., absorbs during its formation, and will give out in its condensation,
as much heat as the steam produced by one pound of water, at 212° F. The
first portion of vapour with a tension = 30 inches, occupies a space of
27·31 cubic feet; the second, with a tension of 0·92 inch, occupies a
space of 890 cubic feet.[29] Suppose that these 890 volumes were to be
compressed into 27·31 in a cylinder capable of confining the heat, the
temperature of the vapour would rise from 77° to 212°, in virtue of the
condensation, as air becomes so hot by compression in a syringe, as to
ignite _amadou_. The latent heat of steam at 212° F. is 1180° - 180 =
1000; that of vapour, at 77°, is 1180 - 45 = 1135°; so that, in fact,
the lower the temperature at which the vapour is exhaled, the greater is
its latent heat, as Joseph Black and James Watt long ago proved by
experiments upon distillation and the steam engine.

  [29] One pound avoirdupois of water contains 27·72 cubic inches; one
  cubic inch of water forms 1696 cubic inches of steam at 212° F.:
  therefore one pound of water will form 27·31 cubic feet of such steam:
  and 0·92 : 30 ∷ 27·31 : 890 cubic feet.

From the preceding researches it follows, that evaporation may be
effected upon two different plans:--

1. Under the ordinary pressure of the atmosphere; and that either,

A, by external application of heat to boilers, with _a_, an open fire;
_b_, steam; _c_, hot liquid _media_.

B, by evaporation with air; _a_, at the ordinary temperature of the
atmosphere; _b_, by currents of warm air.

2. Under progressively lower degrees of pressure than the atmospheric,
down to evaporation in as perfect a vacuum as can be made.

It is generally affirmed, that a thick metallic boiler obstructs the
passage of the heat through it so much more than a thin one, as to make
a considerable difference in their relative powers of evaporating
liquids. Many years ago, I made a series of experiments upon this
subject. Two cylindrical copper pans, of equal dimensions, were
provided; but the metal of the one was twelve times thicker than that of
the other. Each being charged with an equal volume of water, and placed
either upon the same hot plate of iron, or immersed, to a certain depth,
in a hot solution of muriate of lime, I found that the ebullition was
greatly more vigorous in the thick than in the thin vessel, which I
ascribed to the conducting substance up the sides, above the contact of
the source of heat, being 12 times greater in the former case than in
the latter.

If the bottom of a pan, and the portions of the sides, immersed in a hot
fluid medium, solution of caustic potash or muriate of lime, for
example, be corrugated, so as to contain a double expanse of metallic
surface, that pan will evaporate exactly double the quantity of water,
in a given time, which a like pan, with smooth bottom and sides, will do
immersed equally deep in the same bath. If the corrugations contain
three times the quantity of metallic surface, the evaporation will be
threefold in the above circumstances. But if the pan, with the same
corrugated bottom and sides, be set over a fire, or in an oblong flue,
so that the current of flame may sweep along the corrugations, it will
evaporate no more water from its interior than a smooth pan of like
shape and dimensions placed alongside in the same flue, or over the same
fire. This curious fact I have verified upon models constructed with
many modifications. Among others, I caused a cylindrical pan, 10 inches
diameter, and 6 inches deep, to be made of tin-plate, with a vertical
plate soldered across its diameter; dividing it into two equal
semi-cylindrical compartments. One of these was smooth at the bottom,
the other corrugated; the former afforded as rapid an evaporation over
the naked fire as the latter, but it was far outstripped by its
neighbour when plunged into the heated liquid medium.

If a shallow pan of extensive surface be heated by a subjacent fire, by
a liquid medium, or a series of steam pipes upon its bottom; it will
give off less vapour in the same time when it is left open, than when
partially covered. In the former case, the cool incumbent air
precipitates by condensation a portion of the steam, and also opposes
considerable mechanical resistance to the diffusion of the vaporous
particles. In the latter case, as the steam issues with concentrated
force and velocity from the contracted orifice, the air must offer less
proportional resistance, upon the known hydrostatic principle of the
pressure being as the areas of the respective bases, in communicating
vessels.

In evaporating by surfaces heated with ordinary steam, it must be borne
in mind that a surface of 10 square feet will evaporate fully one pound
of water per minute, or 725 × 10 = 7250 gr., the same as over a naked
fire; consequently the condensing surface must be equally extensive.
Suppose that the vessel is to receive of water 2500 libs, which
corresponds to a boiler 5 feet long, 4 broad, and 2 deep, being 40 cubic
feet by measure, and let there be laid over the bottom of this vessel 8
connected tubes, each 5 inches in diameter and 5 feet long, possessing
therefore a surface of 5 feet square. If charged with steam, they will
cause the evaporation of half a pound of water per minute. The boiler to
supply the steam for this purpose must expose a surface of 5 square feet
to the fire. It has been proved experimentally that 10 square feet
surface of thin copper can condense 3 libs of steam per minute, with a
difference of temperature of 90 degrees Fahr. In the above example, 10
square feet evaporate 1 lib. of water per minute; the temperature of the
evaporating fluid being 212° F., consequently 3 : 1 ∷ 90 : 90/3. During
this evaporation the difference of the temperature is therefore = 30°.
Consequently the heat of the steam placed in connection with the
interior of the boiler, to produce the calculated evaporation should be,
212 + 30 = 242°, corresponding to an elastic force of 53·6 inches of
mercury. Were the temperature of the steam only 224, the same boiler in
the same time would produce a diminished quantity of steam, in the
proportion of 12 to 30; or to produce the same quantity the boiler or
tubular surface should be enlarged in the proportion of 30 to 12. In
general, however, steam boilers employed for this mode of evaporation
are of such capacity as to give an unfailing supply of steam.

[Illustration: 381]

I shall now illustrate by some peculiar forms of apparatus, different
systems of evaporation. _Fig._ 381. explains the principles of
evaporating in vacuo. A B represents a pan or kettle charged with the
liquor to be evaporated. The somewhat wide orifice _c_, secured with a
screw-plug, serves to admit the hand for the purpose of cleaning it
thoroughly out when the operation is finished; _h_ is the pipe of
communication with the steam boiler; _b_ is a tube prolonged and then
bent down with its end plunged into the liquor to be evaporated,
contained in the charging back, (not shown in the figure). H is a glass
tube communicating with the vacuum pan at the top and bottom, to shew by
the height of the column the quantity of liquid within. The eduction
evaporating pipe C is provided with a stop-cock to cut off the
communication when required. _i_ is a tube for the discharge of the air
and the water from the steam-case or jacket; the refrigerator E is best
formed of thin copper tubes about 1 inch in diameter, arranged zig-zag
or spirally like the worm of a still in a cylinder. The small air-tight
condenser F, connected with the efflux pipe _f_ of the refrigerator, is
furnished below with a discharge cock _g_, and surrounded by a cooling
case, for the collection of the water condensed by the refrigerator. In
its upper part there is a tube _k_, also furnished with a cock, which
communicates with the steam boiler, and through which the pan A B is
heated.

The operation of this apparatus is as follows: after opening the cocks
C, _f_, _g_, and before admitting the cold water into the condenser E,
the cock of the pipe _k_ is opened, in order that by injecting steam it
may expel the included air; after which the cocks _k_ and _g_ are to be
shut. The water must now be introduced into the condenser, and the cock
_b_ opened, whereon the liquid to be evaporated rises from the charging
back, through the tube _b_, and replenishes the vacuum pan to the proper
height, as shown by the register glass tube H. Whenever the desired
evaporation or concentration is effected, the cock C must be closed, the
pipe _k_ opened, so as to fill the pan with steam, and then the efflux
cock _a_ is opened to discharge the residuary liquor. By shutting the
cocks _a_ and _k_, and opening the cock _b_, the pan will charge itself
afresh with liquor, and the operation will be begun anew, after _b_ has
been shut and C opened.

The contents of the close water cistern F, may be drawn off during each
operation. For this purpose, the cock _f_ must first be shut, the cold
water is to be then run out of the condenser G, and _k_ and _g_ are to
be opened. The steam entering by _k_ makes the water flow, but whenever
the steam itself issues from the cock _g_, this orifice must be
immediately shut, the cock _f_ opened, and the cold water again
introduced, whereupon the condensed water that had meanwhile collected
in the under part of the refrigerator, flows off into the condenser
vessel F. Since some air always enters with the liquor sucked into the
pan, it must be removed at the time of drawing off the water from the
two condensers, by driving steam through the apparatus. This necessity
will be less urgent if the liquor be made to boil before being
introduced into the vacuum pan.

Such an apparatus may be modified in size and arrangement to suit the
peculiar object in view, when it will be perfectly adapted for the
concentration of extracts of every kind, as well as saline solutions
containing vegetable acids or alkalis. The interior vessel of A B should
be made of tinned or plated copper. For an account of Howard’s vacuum
pan, made upon the same principle, see SUGAR.

When a boiler is set over a fire, its bottom should not be placed too
near the grate, lest it refrigerate the flame, and prevent that vivid
combustion of the fuel essential to the maximum production of heat by
its means. The evil influence of leaving too little room between the
grate and the copper may be illustrated by a very simple experiment. If
a small copper or porcelain capsule containing water be held over the
flame of a candle a little way above its apex, the flame will suffer no
abatement of brightness or size, but will continue to keep the water
briskly boiling. If the capsule be now lowered into the middle of the
flame, this will immediately lose its brightness, becoming dull and
smoky covering the bottom of the capsule with soot; and, owing to the
imperfect combustion, though the water is now surrounded by the flame,
its ebullition will cease.

[Illustration: 382]

_Fig._ 382. is a section of two evaporating coppers _en suite_, so
mounted as to favour the full combustion of the fuel. A is the hearth,
in which wood or coal may be burned. For coal, the grate should be set
higher and be somewhat smaller, _a_ is the door for feeding the fire;
_d_, an arch of fire-bricks over the hearth; _c_, a grate through which
the ashes fall into the pit beneath, capable of being closed in front to
any extent by a sliding door _b_. B and C are two coppers encased in
brickwork; _f_ the flue. At the end of the hearth near _m_, where the
fire plays first upon the copper, the sole is made somewhat lower and
wider, to promote the spreading of the flame under the vessel. The
second copper, C, receives the benefit of the waste heat; it may be
placed upon a higher level, so as to discharge its concentrated liquor
by a stop-cock or syphon into the first. When coals are burned for
heating such boilers, the grate should be constructed as shown in the
figure of the brewing copper, page 116.

_Fig._ 383. represents a pan for evaporating liquids, which are apt,
during concentration, to let fall crystals or other sediment. These
would be injured either by the fire playing upon the bottom of the pan,
or, by adhesion to it, they would allow the metal to get red hot, and in
that state run every risk of being burnt or rent on the sudden intrusion
of a little liquor through the incrustation. When large coppers have
their bottoms planted in loam, so that the flame circulates in flues
round their sides, they are said to be _cold-set_.

[Illustration: 383]

A is a pear-shaped pan, charged with the liquid to be evaporated; it is
furnished with a dome cover, in which there is an opening with a flange
_f_, for attaching a tube, to conduct the steam wherever it may be
required. _a_ is the fire-place; _b_, the ash-pit. The conical part
terminates below in the tube _g_, furnished with a stop-cock at its
nozzle _h_. Through the tube _c d c´_, furnished above and below with
the stop-cocks _c_ and _c´_, the liquid is run from the charging back
or reservoir. During the operation, the upper cock _c_ is kept partially
open, to replace the fluid as it evaporates; but the under cock _c´_ is
shut. The flame from the fire-place plays round the kettle in the space
_e_, and the smoke escapes downwards through the flue _i_ into the
chimney. The lower cylindrical part _g_, remains thus comparatively
cool, and collects the crystalline or other solid matter. After some
time, the under stop-cock _c´_, upon the supply-pipe, is to be opened to
admit some of the cold liquor into the cylindrical neck. That cock being
again shut, the sediment settled, and the large stop-cock (a horizontal
slide-valve would be preferable) _h_ opened, the crystals are suffered
to descend into the subjacent receiver; after which the stop-cock _h_ is
shut, and the operation is continued. A construction upon this principle
is well adapted for heating dyeing coppers, in which the sediment should
not be disturbed, or exposed to the action of the fire. The fire-place
should be built as for the brewing copper.

[Illustration: 384]

_Fig._ 384. represents an oblong evaporating pan, in which the flame,
after beating along its bottom, turns up at its further end, plays back
along its surface, and passes off into the chimney. A is a rectangular
vessel, from 10 to 15 feet long, 4 to 6 feet broad, and 1 or 1-1/2 feet
deep. The fire-bricks, upon which the pan rests, are so arranged as to
distribute the flame equably along its bottom.


EUDIOMETER, is the name of any apparatus subservient to the chemical
examination of the atmospheric air. It means a _measure of purity_, but
it is employed merely to determine the proportion of oxygen which it may
contain. The explosive eudiometer, in which about two measures of
hydrogen are introduced into a graduated glass tube, containing five
measures of atmospheric air, and an electric spark is passed across the
mixture, is the best of all eudiometers; and of these the syphon form,
proposed by me in a paper published by the Royal Society of Edinburgh in
1819, is probably the surest and most convenient. Volta’s explosive
eudiometer as made in Paris, costs 3 guineas; mine may be had nicely
graduated for 6 or 8 shillings.


EXPANSION (Eng. and Fr.; _Ausdehnung_, Germ.), is the increase of bulk
experienced by all bodies when heated, unless a change of chemical
texture takes place, as in the case of clays in the potter’s kiln. Table
I. exhibits the linear expansion of several solids by an increase of
temperature from 32° to 212° Fahr.; Table II. exhibits the expansion in
bulk of certain liquids.

TABLE I.--_Linear Dilatation of Solids by Heat._

Dimensions which a bar takes at 212°, whose length at 32° is 1·000000.

  +--------------------+-----------------------+-----------+----------+
  |                    |                       |Dilatation |Dilatation|
  |   Substances.      |     Authority.        |   in      | in Vulgar|
  |                    |                       |Decimals.  |Fractions.|
  +--------------------+-----------------------+-----------+----------+
  |Glass tube,         |Smeaton,               |1·00083333 |          |
  |    do.             |Roy,                   |1·00077615 |          |
  |    do.             |Deluc’s mean,          |1·00082800 | 1/1116   |
  |    do.             |Dulong and Petit,      |1·00086130 | 1/1148   |
  |    do.             |Lavoisier and Laplace, |1·00081166 | 1/1122   |
  |Plate glass,        |   do.         do.     |1·000890890| 1/1142   |
  |    do. crown glass,|   do.         do.     |1·00087572 | 1/1114   |
  |    do.      do.    |   do.         do.     |1·00089760 | 1/1090   |
  |    do.      do.    |   do.         do.     |1·00091751 |          |
  |    do. rod,        |Roy,                   |1·00080787 |          |
  |Deal,               |Roy, as glass,         |    --     |          |
  |Platina,            |Borda,                 |1·00085655 |          |
  |   do.              |Dulong and Petit,      |1·00088420 | 1/1131   |
  |   do.              |Troughton,             |1·00099180 |          |
  |   do. and glass,   |Berthoud,              |1·00110000 |          |
  |Palladium,          |Wollaston,             |1·00100000 |          |
  |Antimony,           |Smeaton,               |1·00108300 |          |
  |Cast-iron prism,    |Roy,                   |1·00110940 |          |
  |Cast-iron,          |Lavoisier, by Dr Young |1·00111111 |          |
  |Steel,              |Troughton,             |1·00118990 |          |
  |Steel rod,          |Roy,                   |1·00114470 |          |
  |Blistered Steel,    |Phil. Trans. 1795, 428,|1·00112500 |          |
  |    do.             |Smeaton,               |1·00115000 |          |
  |Steel not tempered, |Lavoisier and Laplace, |1·00107875 |  1/927   |
  |  do. do.   do.     |    do.        do.     |1·00107956 |  1/926   |
  |  do. tempered yel- |                       |           |          |
  |                low,|    do.        do.     |1·00136900 |          |
  |  do.     do.   do. |    do.        do.     |1·00138600 |          |
  |  do.     do.   do. |                       |           |          |
  |   at a higher heat,|    do.        do.     |1·00123956 |  1/807   |
  |Steel,              |Troughton,             |1·00118980 |          |
  |Hard Steel,         |Smeaton,               |1·00122500 |          |
  |Annealed steel,     |Muschenbroek,          |1·00122000 |          |
  |Tempered steel,     |    do.                |1·00137000 |          |
  |Iron,               |Borda,                 |1·00115600 |          |
  |  do.               |Smeaton,               |1·00125800 |          |
  |Soft iron, forged,  |Lavoisier and Laplace, |1·00122045 |          |
  |Round iron, wire    |                       |           |          |
  |              drawn,|    do.        do.     |1·00123504 |          |
  |Iron wire,          |Troughton,             |1·00144010 |          |
  |Iron,               |Dulong and Petit,      |1·00118203 |  1/846   |
  |Bismuth,            |Smeaton,               |1·00139200 |          |
  |Annealed gold,      |Muschenbroek,          |1·00146000 |          |
  |Gold,               |Ellicot, by comparison,|1·00150000 |          |
  |  do. procured by   |                       |           |          |
  |           parting, |Lavoisier and Laplace, |1·00146606 |  1/682   |
  |     do. Paris stan-|                       |           |          |
  |   dard, unannealed,|    do.        do.     |1·00155155 |  1/645   |
  |  do.     do.       |                       |           |          |
  |           annealed,|    do.        do.     |1·00151361 |  1/661   |
  |Copper,             |Muschenbroek,          |1·0019100  |          |
  |  do.               |Lavoisier and Laplace, |1·00172244 |  1/581   |
  |  do.               |    do.        do.     |1·00171222 |  1/584   |
  |  do.               |Troughton,             |1·00191880 |          |
  |  do.               |Dulong and Petit,      |1·00171821 |  1/582   |
  |Brass,              |Borda,                 |1·00178300 |          |
  |  do.               |Lavoisier and Laplace, |1·00186671 |          |
  |  do.               |    do.        do.     |1·00188971 |          |
  |Brass scale, sup-   |                       |           |          |
  | posed from Hamburg,|Roy,                   |1·00185540 |          |
  |Cast brass,         |Smeaton,               |1·00187500 |          |
  |English plate-brass,|                       |           |          |
  |             in rod,|Roy,                   |1·00189280 |          |
  |  do.    do.  in a  |                       |           |          |
  |        trough form,|  do.                  |1·00189490 |          |
  |Brass,              |Troughton,             |1·00191880 |          |
  |Brass wire,         |Smeaton,               |1·00193000 |          |
  |Brass,              |Muschenbroek,          |1·00216000 |          |
  |Copper 8, tin 1,    |Smeaton,               |1·00181700 |          |
  |Silver,             |Herbert,               |1·00189000 |          |
  |  do.               |Ellicot, by comparison,|1·0021000  |          |
  |  do.               |Muschenbroek,          |1·00212000 |          |
  |  do. of cupel,     |Lavoisier and Laplace, |1·00190974 |  1/524   |
  |  do. Paris stan-   |                       |           |          |
  |               dard,|    do.        do.     |1·00190868 |  1/524   |
  |Silver,             |Troughton,             |1·0020826  |          |
  |Brass 16, tin 1,    |Smeaton,               |1·00190800 |          |
  |Speculum metal,     |    do.                |1·00193300 |          |
  |Spelter solder;     |                       |           |          |
  |    brass 2, zinc 1,|    do.                |1·00205800 |          |
  |Malacca tin,        |Lavoisier and Laplace, |1·00193765 |  1/516   |
  |Tin from Falmouth,  |    do.        do.     |1·00217298 |  1/462   |
  |Fine pewter,        |Smeaton,               |1·00228300 |          |
  |Grain tin,          |do.                    |1·00248300 |          |
  |Tin,                |Muschenbroek,          |1·00284000 |          |
  |Soft solder; lead 2,|                       |           |          |
  |              tin 1,|Smeaton,               |1·00250800 |          |
  |Zinc 8, tin 1, a    |                       |           |          |
  |    little hammered,|  do.                  |1·00269200 |          |
  |Lead.               |Lavoisier and Laplace, |1·00284836 |  1/351   |
  |  do.               |Smeaton,               |1·00286700 |          |
  |Zinc,               |  do.                  |1·00294200 |          |
  |Zinc, hammered out  |                       |           |          |
  |  1/2 inch per foot,|  do.                  |1·00301100 |          |
  |Glass, from 32°, to |                       |           |          |
  |               212°,|Dulong and Petit,      |1·00086130 |  1/1161  |
  |  do. from 212°, to |                       |           |          |
  |               392°,|  do.       do.        |1·00091827 |  1/1089  |
  |  do. from 392°, to |                       |           |          |
  |               572°,|  do.       do.        |1·00101114 |  1/987   |
  +--------------------+-----------------------+-----------+----------+

The last two measurements by an air thermometer.

TABLE II.

_Expansion of certain Liquids by being Heated from 32° to 212°._

  +----------------------------+-----------------+----------+----------+
  |                            |                 |Expansion |Expansion |
  |         Substances.        |    Authority.   |   in     |in Vulgar |
  |                            |                 |Decimals. |Fractions.|
  +----------------------------+-----------------+----------+----------+
  |Mercury,                    |Dulong and Petit.|0·01801800| 1/55·5   |
  |do.      in glass,          |  do.       do.  |0·01543200| 1/65     |
  |Water, from its maximum     |                 |          |          |
  |density,                    |Kirwan.          |0·04332   | 1/23     |
  |Muriatic acid (sp. gr.      |                 |          |          |
  |1·137),                     |Dalton.          |0·0600    | 1/17     |
  |Nitric acid (sp. gr. 1·40), |  do.            |0·1100    | 1/9      |
  |Sulphuric acid (sp. gr.     |                 |          |          |
  |1·85),                      |  do.            |0·0600    | 1/17     |
  |Alcohol (to its boiling     |                 |          |          |
  |point)?                     |  do.            |0·1100    | 1/9      |
  |Water,                      |  do.            |0·0460    | 1/22     |
  |Water, saturated with common|                 |          |          |
  |salt,                       |  do.            |0·0500    | 1/20     |
  |Sulphuric ether (to its     |                 |          |          |
  |boiling point)?             |  do.            |0·0700    | 1/14     |
  |Fixed oils,                 |  do.            |0·0800    | 1/12·5   |
  |Oil of turpentine,          |  do.            |0·0700    | 1/14     |
  +----------------------------+-----------------+----------+----------+

  If the density of water at 39° be called                    1·00000,
                 at 212° it becomes                           0·9548,
                 and its volume has increased to              1·04734;
                 at 77° it becomes                            0·9973587,
                 and its volume has increased to only         1·00265,
  which, though one fourth of the whole range of temperature,
                 is only 1/18 of the total expansion.
                 Water at 60° F. has a specific gravity of    0·9991953,
                 and has increased in volume from 39° to      1·00008,
  which is only about 1/58 of the total expansion to 212°, with 1/64 of
  the total range of temperature.

All gases expand the same quantity by the same increase of temperature,
which from 32° to 212° Fahr. = 180°/480 = 3/8, or 100 volumes become
137·5. For each degree of Fahr. the expansion is 1/480.

When dry air is saturated with moisture, its bulk increases, and its
specific gravity diminishes, because aqueous vapour is less dense than
air, at like temperatures.

The following Table gives the multipliers to be employed for converting
one volume of moist gas at the several temperatures, into a volume of
dry gas.

  +------------+-----------+
  |Temperature.|Multiplier.|
  +------------+-----------+
  |   53° F.   |  0·9870   |
  |   54       |  0·9864   |
  |   55       |  0·9858   |
  |   56       |  0·9852   |
  |   57       |  0·9846   |
  |   58       |  0·9839   |
  |   59       |  0·9833   |
  |   60       |  0·9827   |
  |   61       |  0·9820   |
  |   62       |  0·9813   |
  |   63       |  0·9806   |
  |   64       |  0·9799   |
  |   65       |  0·9793   |
  |   66       |  0·9786   |
  |   67       |  0·9779   |
  |   68       |  0·9772   |
  |   69       |  0·9765   |
  |   70       |  0·9758   |
  |   71       |  0·9751   |
  |   72       |  0·9743   |
  |   73       |  0·9735   |
  +------------+-----------+


EXTRACTS. (_Extraits_, Fr.; _Extracten_, Germ.) The older apothecaries
used this term to designate the product of the evaporation of any
vegetable juice, infusion, or decoction; whether the latter two were
made with water, alcohol, or ether; whence arose the distinction of
aqueous, alcoholic, and ethereous extracts.

Fourcroy made many researches upon these preparations, and supposed that
they had all a common basis, which he called the _extractive_ principle.
But Chevreul and other chemists have since proved that this pretended
principle is a heterogeneous and very variable compound. By the term
_extract_ therefore is now meant merely the whole of the soluble matters
obtained from vegetables, reduced by careful evaporation to either a
pasty or solid consistence. The watery extracts, which are those most
commonly made, are as various as the vegetables which yield them; some
containing chiefly sugar or gum in great abundance, and are therefore
innocent or inert; while others contain very energetic impregnations.
The conduct of the evaporating heat is the capital point in the
preparation of extracts. They should be always prepared if possible from
the juice of the fresh plant, by subjecting its leaves or other
succulent part, to the action of a powerful screw or hydraulic press;
and the evaporation should be effected by the warmth of a water bath,
heated not beyond 100° or 120° F. Steam heat may perhaps be applied
advantageously in some cases, where it is not likely to decompose any of
the principles of the plant. But by far the best process for making
extracts is in vacuo, upon the principles explained in the article
EVAPORATION. It is much easier to fit up a proper apparatus of this
kind, than most practical men imagine. The vacuum may either be made
through the agency of steam, as there pointed out, or by means of an
air-pump. One powerful air-pump may form and maintain a good vacuum
under several receivers, placed upon the flat-ground flanges of so many
basins, each provided with a stop-cock at its side for exhaustion. The
air-less basin containing the juice being set on the shelf of a
water-bath, and exposed to a proper temperature, will furnish in a short
time, a large quantity of medicinal extract, possessing the properties
of the plant unimpaired.

For exceedingly delicate purposes, the concentration may be performed in
the cold, by placing saucers filled with the expressed juice over a
basin containing sulphuric acid, putting a glass receiver over them, and
exhausting its air.




F.


FAHLERZ. Gray copper-ore, called also Panabase, from the many oxides it
contains.


FAINTS, is the name of the impure spirit, which comes over first and
last in the distillation of whiskey; the former being called the
_strong_, and the latter, which is much more abundant, the _weak_
faints. This crude spirit is much impregnated with fetid essential oil,
is therefore very unwholesome, and must be purified by rectification.


FAN (_Eventail_, Fr.; _Fächer_, Germ.); is usually a semi-circular piece
of silk or paper, pasted double, enclosing slender slips of wood, ivory,
tortoise-shell, whale-bone, &c., arranged like the tail of a peacock in
a radiating form, and susceptible of being folded together, and expanded
at pleasure. This well-known hand ornament is used by ladies to cool
their faces by agitating the air. Fans made of feathers, like the wing
of a bird, have been employed from time immemorial by the natives of
tropical countries.

_Fan_ is also the name of the apparatus for winnowing corn. For an
account of the powerful blowing and ventilating fan machine, see FOUNDRY
and VENTILATOR.


FARINA (_Farine_, Fr.; _Mehl_, Germ.); is the flour of any species of
corn, or starchy root, such as potato, arrow root, &c. See BREAD and
STARCH.


FATS, (_Graisses_, Fr.; _Fette_, Germ.) occur in a great number of the
animal tissues, being abundant under the skin in what is called the
cellular membrane, round the kidneys, in the folds of the omentum, at
the base of the heart, in the mediastinum, the mesenteric web, as well
as upon the surface of the intestines, and among many of the muscles.
They vary in consistence, colour, and smell, according to the animals
from which they are obtained; thus, they are generally fluid in the
cetaceous tribes, soft and rank-flavoured in the carnivorous, solid and
nearly scentless in the ruminants, usually white and copious in well-fed
young animals; yellowish and more scanty in the old. Their consistence
varies also according to the organ of their production; being firmer
under the skin, and in the neighbourhood of the kidneys, than among the
movable viscera. Fat forms about one twentieth of the weight of a
healthy animal. But as taken out by the butcher it is not pure, for
being of a vesicular structure it is always enclosed in membranes, mixed
with blood, blood-vessels, lymphatics, &c. These foreign matters must
first be separated in some measure mechanically, after the fat is minced
small, and then more completely by melting it along with hot water,
passing it through a sieve, and letting the whole cool very slowly. By
this means a cake of cleansed fat will be obtained. Many plans of
purifying fats have been proposed; one of the best is to mix two per
cent. of strong sulphuric acid with a quantity of water, in which the
tallow is heated for some time with much stirring; to allow the
materials to cool, to take off the supernatant fat, and re-melt it with
abundance of hot water. More tallow will thus be obtained, and that
considerably whiter and harder than is usually procured by the melters.

I have found that chlorine, and chloride of lime do not improve, but
rather deteriorate the appearance of oils and other fatty bodies.
According to Appert, minced suet subjected to the action of
high-pressure steam in a digester, at 250° or 260° F., becomes so hard
as to be sonorous when struck, whiter, and capable when made into
candles, of giving a superior light. A convenient mode of _rendering_
minced tallow, or melting it, is to put it in a tub, and drive steam
through it from numerous orifices in ramifying pipes placed near the
bottom. Mr. Watt assures me that his plan of purifying fats, patented in
March 1836, has been quite successful. He employs dilute sulphuric acid,
to which he adds a little nitric acid, with a very small quantity of
bichromate of potash, “to supply oxygen;” and some oxalic acid. These
are mixed with the fat in the steaming tub. When the lumps of it are
nearly dissolved, he takes for every ton of fat, one pound of strong
nitric acid, diluted with one quart of water; to which he adds two
ounces of alcohol, naphta, sulphuric ether, or spirits of turpentine;
and after introducing this mixture, he continues the boiling for half an
hour. The fat is finally washed.--As I do not comprehend the _modus
operandi_ of these ingredients, I shall abstain from any comment upon
the recipe.

Others have proposed to use vegetable or animal charcoal first,
especially for rancid oils, then to heat them with a solution of
sulphate of copper and common salt, which is supposed to precipitate the
fetid albuminous matter. Milk of lime has been also prescribed; but it
is I believe always detrimental.

Davidson treats whale oil with infusion of tan, in order to separate the
gelatine and albumine in flocks; next with water and chloride of lime,
to destroy the smell; and lastly, with dilute sulphuric acid, to
precipitate all the lime in the state of a sulphate. This is certainly
one of the cheapest and most effective methods of purifying that
substance.

Braconnot and Raspail have shown that solid animal fats are composed of
very small, microscopic, partly polygonal, partly reniform particles,
which are connected together by very thin membranes. These may be
ruptured by mechanical means, then separated by triturating the fresh
fats with cold water, and passing the unctuous matter through a sieve.
The particles float in the water, but eventually collect in a white
granular crystalline appearance, like starch. Each of them consists of a
vesicular integument, of the nature of stearine, and an interior fluid
like elaine, which afterwards exudes. The granules float in the water,
but subside in spirits of wine. When digested in strong alcohol, the
liquid part dissolves, but the solid remains. These particles differ in
shape and size, as obtained from different animals; those of the calf,
ox, sheep, are polygonal, from 1/50 to 1/350 of an inch in diameter;
those of the sow are kidney-shaped, and from 1/50 to 1/100; those of man
are polygonal, and from 1/50 to 1/600; those of insects are spherical,
and at most 1/500 of an inch.

Fats all melt at a temperature much under 212° F. When strongly heated
with contact of air, they diffuse white pungent fumes, then blacken, and
take fire. When subjected to distillation, they afford a changed fluid
oil, carburetted hydrogen, and the other products of oily bodies.
Exposed for a certain time to the atmosphere, they become rancid, and
generate the same fat acids as they do by saponification. In their fresh
state they are all composed principally of stearine, margarine, and
oleine, with a little colouring and odorous matter; and, in some
species, hircine, from the goat; phocenine, from the dolphin; and
butyrine, from butter. By subjecting them to a great degree of cold, and
compressing them between folds of blotting paper, a residuum is
obtained, consisting chiefly of stearine and margarine; the latter of
which may be dissolved out by oil of turpentine.

_Beef and Mutton Suet._--When fresh, this is an insipid, nearly
inodorous fat, of a firm consistence, almost insoluble in alcohol,
entirely so if taken from the kidneys and mesenteric web of the ox, the
sheep, the goat, and the stag. It varies in its whiteness, consistence,
and combustibility, with the species and health of the animals. That of
the sheep is very white, and very solid. They may all be purified in the
manner above described. Strong sulphuric acid develops readily the acid
fats by stirring it through melted suet. Alkalis, by saponification,
give rise at once to the three acids,--the stearic, margaric, and oleic.
Beef suet consists of stearine, margarine, and oleine; mutton and goat
suet contain a little hircine. The specific gravity of the tallow, of
which common candles are made is, by my experiments, 0·936. The melting
point of suet is from 98° to 104° F. The proportion of solid and fluid
fat in it is somewhat variable, but the former is in much larger
proportion. Mutton suet is soluble in 44 parts of boiling alcohol, of
0·820; beef suet in 44 parts. Marrow fat consists of 76 of stearine, and
24 of oleine; it melts at 115° F.

_Hog’s-lard_ is soft, fusible at 81° F., convertible, by an alkaline
solution, into a stearate, margarate, oleate, and glycerine. Its sp.
grav. is 0·938, at 50° F; It consists of 62 of oleine, and 38 of
stearine, in 100 parts.

_Goose-fat_, consists of 68 oleine and 32 stearine.

_Butter_, in summer, consists of 60 of oleine and 40 of stearine; in
winter, of 35 of oleine, and 65 of stearine; the former substance being
yellow and the latter white. It differs, however, as produced from the
milk of different cows, and also according to their pasture.

The ultimate constituents of stearine, according to Chevreul are, 79
carbon; 11·7 hydrogen; and 9·3 oxygen, in 100 parts.

1,294,009 cwts. of the tallow imported in 1837, were retained for
internal consumption. See MARGARINE, OLEINE, SOAP, STEARINE.


FAULTS (_Failles_, Fr.); in mining, are disturbances of the strata which
interrupt the miner’s operations, and put him at _fault_, to discover
where the vein of ore or bed of coal has been thrown by the convulsions
of nature. Many examples of faults are exhibited under PITCOAL.


FEATHERS (_Plumes_, Fr.; _Federn_, Germ.), constitute the subject of the
manufacture of the _Plumassier_, a name given by the French (and also
the English) to the artisan who prepares the feathers of certain birds
for ornaments to the toilette of ladies and for military men, and to him
also who combines the feathers in various forms. We shall content
ourselves with describing the method of preparing ostrich feathers, as
most others are prepared in the same way.

Several qualities are distinguished in the feathers of the ostrich;
those of the male, in particular, are whiter and more beautiful. Those
upon the back and above the wings are preferred; next, those of the
wings, and lastly, of the tail. The down is merely the feathers of the
other parts of the body, which vary in length from 4 to 14 inches. This
down is black in the males, and gray in the females. The finest white
feathers of the female have always their ends a little grayish, which
lessens their lustre, and lowers their price. These feathers are
imported from Algiers, Tunis, Alexandria, Madagascar, and Senegal; this
being the order of their value.

The _scouring process_ is thus performed:--4 ounces of white soap, cut
small, are dissolved in 4 pounds of water, moderately hot, in a large
basin; and the solution is made into a lather by beating with rods. Two
bundles of the feathers, tied with packthread, are then introduced, and
are rubbed well with the hands for five or six minutes. After this
soaping they are washed in clear water, as hot as the hand can bear.

The whitening or bleaching is performed by three successive operations.

1. They are immersed in hot water mixed with Spanish white, and well
agitated in it; after which they are washed in three waters in
succession.

2. The feathers are azured in cold water containing a little indigo tied
up in a fine cloth. They should be passed quickly through this bath.

3. They are sulphured in the same way as straw hats are (see
SULPHURING); they are then dried by hanging upon cords, when they must
be well shaken from time to time to open the fibres.

The ribs are scraped with a bit of glass cut circularly, in order to
render them very pliant. By drawing the edge of a blunt knife over the
filaments they assume the curly form so much admired. The hairs of a
dingy colour are dyed black. For 20 pounds of feathers, a strong
decoction is made of 25 pounds of logwood in a proper quantity of water.
After boiling it for 6 hours, the wood is taken out, 3 pounds of
copperas are thrown in; and, after continuing the ebullition for 15 or
20 minutes, the copper is taken from the fire. The feathers are then
immersed by handfuls, thoroughly soaked, and worked about; and left in
for two or three days. They are next cleansed in a very weak alkaline
lye, and soaped three several times. When they feel very soft to the
touch, they must be rinsed in cold water, and afterwards dried. White
feathers are very difficult to dye a beautiful black. The acetate of
iron is said to answer better than the sulphate, as a mordant.

For dyeing other colours, the feathers should be previously well
bleached by the action of the sun and the dew; the end of the tube being
cut sharp like a toothpick, and the feathers being planted singly in the
grass. After fifteen days’ exposure, they are cleared with soap as above
described.

_Rose colour_ or _pink_, is given with safflower and lemon juice.

_Deep red_, by a boiling hot bath of Brazil wood, after aluming.

_Crimson._ The above deep red feathers are passed through a bath of
cudbear.

_Prune de Monsieur._ The deep red is passed through an alkaline bath.

_Blues of every shade_, are dyed with the indigo vat.

_Yellow_; after aluming, with a bath of turmeric or weld.

Other tints may be obtained by a mixture of the above dyes.

Feathers have some more useful employments than the decoration of the
heads of women and soldiers. In one case, they supply us with a soft
elastic down on which we can repose our wearied frames, and enjoy sweet
slumbers. Such are called _bed_ feathers. Others are employed for
writing, and these are called _quills_.

Goose feathers are most esteemed for beds, and they are best when
plucked from the living bird, which is done thrice a year, in spring,
midsummer, and the beginning of harvest. The qualities sought for in bed
feathers, are softness, elasticity, lightness, and warmth. Their only
preparation when cleanly gathered are a slight beating to clear away the
loose matter, but for this purpose they must be first well dried either
by the sun or a stove. Bleaching with lime water is a bad thing, as they
can never be freed from white dust afterwards.

The feathers of the eider duck, _anas mollissima_, called eider down,
possess in a superior degree all the good qualities of goose down. It is
used only as a covering to beds, and never should be slept upon, as it
thereby loses its elasticity.

_Quills_ for writing. These consist usually of the feathers plucked out
of the wings of geese. Dutch quills have been highly esteemed, as the
Dutch were the first who hit upon the art of preparing them well, by
clearing them both inside and outside from a fatty humour with which
they are naturally impregnated, and which prevents the ink from flowing
freely along the pens made with them. The Dutch for a long time employed
hot cinders or ashes to attain this end; and their secret was preserved
very carefully, but it at length transpired, and the process was then
improved. A bath of very fine sand must be kept constantly at a suitable
temperature, which is about 140° F.; into this, the quill end of the
feather must be plunged, and left in it a few instants. On taking them
out they must be strongly rubbed with a piece of flannel, after which
they are found to be white and transparent. Both carbonate of potash in
solution and dilute sulphuric acid have been tried to effect the same
end, but without success. The yellow tint which gives quills the air of
age, is produced by dipping them for a little in dilute muriatic acid,
and then making them perfectly dry. But this process must be preceded by
the sand-bath operation. The above is the French process.

Quills are dressed by the London dealers in two ways; by the one, they
remain of their natural colour; by the other, they acquire a yellow
tint. The former is called the Dutch method, and the principal workman
is called a Dutcher. He sits before a small stove fire, into which he
thrusts the barrel of the quill for about a second, then lays its root
quickly below his blunt-edged knife called a hook, and, pressing this
firmly with the left hand, draws the quill briskly through with his
right. The bed on which the quill is laid to receive this pressure is
called the plate. It is a rectangular smooth lump of iron, about 3
inches long, 1-1/2 broad, and 2-1/2 thick, which is heated on his stove
to about the 350th degree Fahr. The hook is a ruler of about 15 inches
in length, somewhat like the patten-makers’ knife, its fulcrum being
formed at the one end by a hook and staple, and the power of pressure
being applied by the hand at the other end. The quill, rendered soft and
elastic by the heat, endures the strong scraping action of the tool, and
thus gets stripped of its opaque outer membrane, without hazard of being
split. A skilful workman can pass 2000 quills through his hands in a day
of 10 hours.

They are next cleaned by being scrubbed by a woman with a piece of rough
dog-fish skin, and finally tied up by a man in one quarter of hundred
bundles.

In another mode of dressing quills, they are steeped a night in
decoction of turmeric, to stain them yellow; taken out and dried in warm
sand contained in a pot, then scraped by the Dutcher as above described.
The first are reckoned to make the best pens, though the second may
appear more beautiful.

Crow quills for draughtsmen, as well as swan quills, are prepared in the
same way. The quills plucked from well-fed living birds have most
elasticity, and are least subject to be moth-eaten. The best are those
plucked, or which are spontaneously cast in the month of May or June,
because they are then fully ripe. In the goose’s wing the five exterior
feathers only are valuable for writing. The first is the hardest and
roundest of all, but the shortest. The next two are the best of the
five. They are sorted into those of the right and the left wing, which
are differently bent. The heaviest quills are, generally speaking, the
best. Lately, steaming for four hours has been proposed as a good
preparation.


FECULA (_Fecule_, Fr.; _Stärkemehl_, Germ.); sometimes signifies corn
flour, sometimes starch from whatever source obtained.


FELSPAR (_Orthose_, Fr.; _Feldspath_, Germ.) is a mineral crystallizing
in oblique rhomboidal prisms, susceptible of two cleavages; lustre more
pearly than vitreous; spec. grav. 2·39 to 2·58; scratches glass; yields
no water when calcined; fusible at the blowpipe into a white enamel; not
affected by acids. The liquid left from its analytical treatment with
nitrate of baryta, nitric acid, and carbonate of ammonia, affords on
evaporation an alkaline residuum which precipitates platina from its
chloride, and appears from this, as well as other tests, to be potash.
Felspar consists of--silica, 66·75; alumina, 17·50; potash, 12; lime,
1·25; oxide of iron, 0·75. _Rose._ This mineral is a leading constituent
of granite; and in its decomposed state furnishes the petuntse or
Cornish stone, so much used in the porcelain and best pottery
manufactures.


FELTING; (_Feutrage_, Fr.; _Filzen_, Germ.) is the process by which
loose flocks of wool, and hairs of various animals, as the beaver,
rabbit, hare, &c., are mutually interlaced into a compact textile
fabric. The first step towards making felt is to mix, in the proper
proportions, the different kinds of fibres intended to form the stuff;
and then, by the vibratory strokes of the bowstring, to toss them up in
the air, and to cause them to fall as irregularly as possible, upon the
table, opened, spread, and scattered. The workman covers this layer of
loose flocks with a piece of thick blanket stuff slightly moistened; he
presses it with his hands, moving the hairs backwards and forwards in
all directions. Thus the different fibres get interlaced, by their ends
pursuing ever tortuous paths; their vermicular motion being always,
however, root foremost. As the matting gets denser, the hand pressure
should be increased in order to overcome the increasing resistance to
the decussation.

A first thin sheet of soft spongy felt being now formed, a second is
condensed upon it in like manner, and then a third, till the requisite
strength and thickness be obtained. These different pieces are
successively brought together, disposed in a way suitable to the
wished-for article, and united by continued dexterous pressure. The
stuff must be next subjected to the fulling mill. See HAT MANUFACTURE.


FERMENT (Eng. and Fr.; _Hefe_, Germ.) is the substance which, when added
in a small quantity to vegetable or animal fluids, tends to excite those
intestine motions and changes which accompany fermentation. It seems to
be the result of an alteration which vegetable albumen and gluten
undergo with contact of air amidst a fermenting mass. The precipitate or
lees which fall down when fermentation is finished consist of a mixture
of the fermenting principle with the insoluble matters contained in the
fermented liquor, some of which, like hordeine, existed in the worts,
and others are probably generated at the time.

To prepare a pure ferment, or at least a compound rich in that
principle, the precipitate separated during the fermentation of a clear
infusion of malt, commonly called yeast or barm, is made use of. This
pasty matter must be washed in cold distilled water, drained and
squeezed between the folds of blotting paper. By this treatment it
becomes a pulverulent mass, composed of small transparent grains,
yellowish gray when viewed in the compound microscope. It contains much
water, and is therefore soft, like moist gluten and albumen. When dried,
it becomes like these bodies, translucid, yellowish brown, horny, hard,
and brittle. In the soft humid state it is insipid, inodorous, insoluble
in water and alcohol. If, in this state, the _ferment_ be left to itself
at a temperature of from 60° to 70° F., but not in too dry a situation,
it putrefies with the same phenomena as vegetable gluten and albumen,
and leaves, like them, a residuum resembling old cheese.

At the beginning of this change, particularly if the ferment be enclosed
in a limited portion of air, there is an absorption of oxygen gas with a
fivefold disengagement of carbonic acid gas; while acetic acid makes its
appearance in the substance. When distilled by itself it affords the
same products as gluten. Dilute acids dissolve it very readily; and so
does potash with the production of ammonia, a peculiar circumstance, for
in dissolving gluten the alkali causes no such evolution.

The property possessed by yeast of determining the fermentation of a
properly diluted solution of sugar is very fleeting, and is lost by very
trifling alterations. It is destroyed by complete desiccation, and
cannot be restored by moistening it again. The attempts made in London
to squeeze out the liquid part of yeast in bags placed in a powerful
press, and to obtain a solid cake, in order to transport ferment to
India, have had but a very partial success; for its virtue is so
impaired that it will rarely excite a perfect fermentation in the best
prepared worts. The same method is adopted in Germany, to send yeast to
only moderate distances; and therefore with more advantage.

If yeast be boiled for ten minutes, it loses the greater part of its
fermenting power, and by longer boiling it becomes inert.

When alcohol is poured upon yeast, it immediately destroys its
fermenting faculties, though, on filtering it off, it seems to carry no
remarkable principle with it. One thousandth part of sulphuric acid
equally deprives yeast of its peculiar property, and so does a little
strong acetic acid. All the acids and the salts, especially those which
part readily with their oxygen, produce the same effect. A very small
quantity of sulphurous acid, or sulphites, mustard powder, particularly
the volatile oil of mustard, and in general the volatile oils that
contain sulphur, as well as the vegetables which yield them, such as
horse-radish and garlick, all kill the fermenting agent. Lastly,
fermentation is completely stopped by a moderate depression of
temperature.

During fermentation the yeast undergoes a change; it loses the property
of causing another wort to ferment. This change probably depends upon
the chemical reaction between the ferment and the sugar that is
decomposed; for a certain quantity of yeast can effect the fermentation
of only a certain quantity of sugar, and all the sugar exceeding this
quantity remains unaltered in the liquor. It has been concluded from
some rather loose experiments, that one part and a half of yeast
(supposed to be in the dry state), is adequate to the fermentation of a
solution of 100 parts of pure sugar. When such a solution is fermented
by the precise proportion of yeast, the fermenting principle is
exhausted, for no new yeast is formed in it. There is a deposit indeed
to about half the weight of the yeast employed, of a white matter
insoluble in water, which affords no ammonia by dry distillation, and is
incapable of acting as a ferment upon a fresh saccharine solution.

Of all the bodies convertible into yeast during fermentation, vegetable
gluten and albumen possess the most rapid and energetic powers. But
ordinary glue, isinglass, animal fibrine, curd or _caseum_, albumine,
urine and other azotized substances, all enjoy the property of causing
a solution of sugar to ferment; with this difference, that whilst yeast
can establish a complete fermentation in less than an hour, at a
temperature of about 68°, the above substances require several days,
with a heat of from 77° to 87° F., for becoming ferments, and for
occasioning fermentation. Substances devoid of nitrogen do not produce a
ferment.


FERMENTATION. (Eng. and Fr.; _Gährung_, Germ.) When organic substances,
under the influence of water, air, and warmth, are abandoned to the
reciprocal operation of their proximate principles, (sugar, starch,
gluten, &c.), they are entirely changed and decomposed, so that their
ultimate principles (oxygen, hydrogen, carbon, and in some cases azote,)
combine in new proportions, and thus give birth to various new
compounds. To this process, the general name of fermentation has been
given. These operations and their products differ according to the
differences of the substances, and of the circumstances in which they
are placed. The following may be enumerated as sufficiently distinct
species of fermentation. 1. The _saccharine_ fermentation, in which
starch and gum are changed into sugar. 2. The _vinous_ fermentation, in
which sugar is converted into alcohol. 3. The _mucilaginous_
fermentation, in which sugar is converted into slime, instead of
alcohol. 4. The _acetous_ fermentation, in which alcohol and other
substances are converted into vinegar. 5. The _putrid_ fermentation or
putrefaction, which characterizes particularly the decomposition of
azotized organic substances.

1. _The saccharine fermentation._ When a paste made by boiling one part
of starch with twelve parts of water is left entirely to itself, water
merely being stirred in as it evaporates, at the end of a month or two
in summer weather it is changed into sugar, equal in weight to from one
third to one half of the starch, and into gum, equal to from one fifth
to one tenth, with a residuum of starch paste somewhat altered. This
saccharifying process advances much quicker through the co-operation of
vegetable albumine or gluten, acting as a ferment. If we boil two parts
of potato starch into a paste with twenty parts of water, mix this paste
with one part of the gluten of wheat flour, and set the mixture for 8
hours in a temperature of from 122° to 167° F., the mixture soon loses
its pasty character, and becomes by degrees limpid, transparent and
sweet, passing at the same time first into gum, and then into sugar. The
remainder consists of the unchanged starch with the altered gluten,
which has become sour, and has lost the faculty of acting upon fresh
portions of starch. It is probable, however, that the sugar formation in
the first case, when the starch undergoes a spontaneous change, may be
due to the action of a small portion of gluten and albumine left in the
starch, since a putrefactive smell is eventually evolved indicative of
that azotized matter. The gum into which during this process the starch
is first converted, and which becomes afterwards sugar, is of the same
nature as British gum, formed by the roasting of starch.

This production of sugar takes place in the germination and kiln-drying
of malt; and the mashing of the brewer as well as the sweetening of
bread in baking, rests upon the same principles. In many cases the
vinous fermentation precedes the saccharification, or accompanies it;
the starchy parts of the fermenting mass changing into sugar, while the
previously formed sugar becomes wine or beer. In the sweetening of
fruits by keeping, a similar process occurs; the gummy and starchy
fibres become sugar from the action of the glutinous ferment which they
contain; as happens also to the juices of many fruits which sweeten for
a little while after they have been expressed.

The nature of this sugar formation through the influence of gluten upon
starch, is undoubtedly the same as the conversion of starch into sugar,
by boiling it with sulphuric acid; though the whole theory of this
change is not entirely developed.

The most energetic substance for the conversion of starch into sugar, is
the malt of barley. According to the researches of Payen and Persoz, the
gum which by this process is first formed, may be prevented from going
into sugar, by merely exposing it to a boiling heat, and hence we have
it in our power either to make sugar or gum at pleasure. Of finely
ground malt from 10 to 25 parts must be taken for 100 parts of starch.
Into a pan placed in a water bath, 400 parts of water being warmed to
from 77° to 86° F., the ground malt must be stirred in, and the
temperature must be raised to 140°. The 100 parts of starch must now be
added, and well mixed. The heat is then to be increased to 158°F.; and
be so regulated that it shall not fall below 149°, nor rise above 167°.
In the course of 20 or 30 minutes the originally milky and pasty liquid
will become gradually more attenuated, and eventually it will turn as
fluid nearly as water. This is the point of time in which the starch has
passed into gum, or into the substance lately denominated _dextrine_ by
the chemists. Should this mucilaginous matter, which appears to be a
mixture of gum and a little starchy sugar, be wished for in that state,
the temperature of the liquid must be suddenly raised to the boiling
point, whereby the further action of the malt upon it is stopped. But on
the other hand if sugar be desired, then the temperature must be
steadily maintained at from 158° to 167° for three quarters of an hour,
in which time the greater part of the starch will have become sugar,
and from the evaporation of the fluid a starchy syrup will be obtained,
entirely similar to that procurable by the action of very dilute
sulphuric acid upon starch.

The substance which operates this saccharine change, or the appropriate
yeast of the sugar fermentation, which had been previously imagined to
be a residuum of gluten or vegetable albumen in the germinated grain,
has been traced by Payen and Persoz to a peculiar proximate vegetable
principle called by them _diastase_. This substance is generated during
the germination of barley, oats, and wheat, and may be obtained
separately by infusing the ground malt in a small quantity of cold
water, straining off the liquor, then filtering it, and heating the
clear solution in a water bath to the temperature of 158° F. The greater
part of the vegetable albumen is thus coagulated, and must be separated
by a fresh filtration; the liquid is afterwards treated with alcohol as
long as the flocculent precipitate of diastase falls. In order to purify
it still more completely from the azotized matter, it may be once more
dissolved in water, and again precipitated by alcohol. When dried at a
low temperature, it appears as a white solid, which contains no azote,
is insoluble in strong alcohol, but dissolves in weak alcohol and water.
Its solution is neutral and tasteless; and if left to itself, it changes
spontaneously sooner or later according to the degree of warmth, and
becomes sour. At the temperature of from 149° to 168°, it has the
property of converting starch into gum or dextrine, and sugar; and, when
sufficiently pure, it does this with such energy, that one part of it is
capable of saccharifying 2000 parts of dry starch. It acts the more
rapidly the larger its proportion. Whenever the solution of diastase
with starch or dextrine, has been heated to the boiling point, it loses
the property of transforming these substances. One hundred parts of well
malted barley appear to contain about one part of this new body.

2. _The Vinous Fermentation._--In this fermentation the sugar existing
in watery solution is, by the operation of the ferment or yeast,
converted into alcohol, with disengagement of carbonic acid gas. If we
dissolve one part of pure sugar in ten parts of water, and leave the
solution in a temperature of from 68° to 77° F., which is that most
favourable to fermentation, it will remain unaltered. But if we stir
into that solution some beer yeast, the phenomena of fermentation soon
appear in the above circumstances; for carbonic acid gas is evolved,
with intestine movements of the liquid, and an increase of its
temperature. A body of yeast rises to the surface, and exhibits a
continual formation and rupture of air bubbles. At length the sugar
being in a great measure decomposed, the motions cease, the liquor
becomes clear, and instead of being a syrup, it is now a dilute alcohol.
The yeast has by this time fallen to the bottom in a somewhat compact
form, and of a whitish colour, deprived of the property of exciting
fermentation in fresh syrup, provided no undue excess of it was added at
first, for that alone would remain effective. Experience shows that for
the conversion of a determinate quantity of sugar by fermentation, a
determinate quantity of yeast is necessary, which has been estimated at
about 1-1/2 per cent. in the dry state. When the yeast has been
decomposed by fermenting its definite proportion of sugar, it loses its
fermentable property, and leaves the excess of sugar unaffected, forming
a sweet vinous solution. The same thing happens if the yeast be
separated from the wort by a filter in the progress of the fermentation,
for then all intestine motion speedily stops, although much saccharine
matter remains.

In the juices of sweet fruits, of grapes, for example, the ferment is
intimately associated with the sugar. It is at first soluble and
inactive, till it absorbs oxygen from the atmosphere, whereby it becomes
an operative ferment, but, at the same time, insoluble, so as to
precipitate at the end of the process. When the expressed juice of the
grape, or _must_, is inclosed in a vessel out of contact of air, and
there subjected to the heat of boiling water, the small portion of
oxygen present is rendered inactive, and the liquor experiences no
fermentative change. If the grapes be squeezed in an atmosphere deprived
of oxygen, and confined in the same, the juice will also remain
unaltered. Recently expressed grape juice is limpid, and manifests the
commencement of fermentation by the separation of the yeasty substance,
which can take place only with access of air. The solution becomes
turbid after a certain time, gas begins to be evolved, and the separated
ferment decomposes the sugar. At the end of the process the yeast
collects at the bottom of the vessel, usually in larger quantity than
was sufficient to complete the fermentation; and hence a considerable
portion of it possesses still the fermentative faculty. The fermentation
itself, when once begun, that is, whenever the yeasty particles are
evolved, and float in the liquid, for which evolution a very minute
quantity of oxygen is sufficient, is thenceforth independent of the
contact of air, and goes on as well in close as in open vessels; so that
the production of alcohol and carbonic acid depends solely upon the
mutual reaction of the ferment and the sugar.

The yeast, which may be obtained tolerably pure from a fine infusion of
malt in a state of fermentation, after being washed with cold water to
separate the soluble, gummy, and saccharine matter, and after being
pressed between folds of blotting paper, constitutes a pulverulent,
grayish yellow, granular substance, destitute of both taste and smell,
insoluble both in water and alcohol. Cold water dissolves, indeed, only
1/400, and boiling water very little more.

The essentially operative constituent of yeast is a peculiar azotized
matter, which in the wine vat is mixed with some tartar and other salts,
and in the beer tun with gum, starch, &c. This animalized substance may
be obtained in a separate state, according to Braconnot, by acting upon
the washed yeast powder with a weak lye of carbonate of potash, and by
decomposing the solution with vinegar, whereby the matter is thrown down
in a gelatinous form. The substance thus obtained is insoluble in cold
water and alcohol, but dissolves readily in very dilute alkaline lyes,
and even in lime water. When diffused through water, it assumes a
homogeneous aspect, as if it were really dissolved; but when this
mixture is heated, the animalized matter coagulates, and separates in
thick flocks. In this state it has lost its former properties, being no
longer soluble in alkaline lyes, even when concentrated. Acids exercise
no solvent power over this peculiar matter; they precipitate it from its
solutions, as do also the earthy and metallic salts, which, moreover,
combine with it. This is also the case with tannin. The combination of
the ferment stuff with acids increases the stability of its
constitution, and counteracts its tendency to influence solutions of
sugar. These properties of the operative principle of yeast explain many
of the phenomena of fermentation, as we shall presently see.

The animalized matter of yeast resembles gluten, albumen, caseum, and
other azotized substances; if any one of these be put into a saccharine
solution ready for fermentation, it will begin to operate a change, when
aided by warmth and time, if it be previously decomposed in some measure
to facilitate its influence; or if these substances be brought into a
slightly putrescent state beforehand, they will cause more speedy
fermentation. Thus white of egg, when added to saccharine liquors,
requires a period of three weeks, with a temperature of 96° F., before
it will excite fermentation; afterwards the excess of the albumen forms
a precipitate which may be used instead of yeast upon other sweet worts.
The rapidity with which such azotized substances are capable of being
converted into ferments of more or less purity and power is very
variable; vegetable gluten and albumen being best fitted for this
purpose. This conversion is accelerated when the sweet liquor in which
the substance is diffused or dissolved has already begun to ferment;
whence it appears that the presence of carbonic acid gas, combined with
the liquor, is here of singular influence. Upon it, in fact, the
formation and elimination of the yeast in fermenting liquors depend.

A solution of pure sugar, which has been made to ferment by the addition
of yeast, furnishes no new yeast; but there remains after the process a
portion of the yeast originally mixed, in an altered inoperative
condition, should its quantity have been exactly adequate to the
decomposition of the sugar, or in an operative state, should the
quantity have been originally excessive.

But if the fermentable liquor contains vegetable albumen and gluten, as
is commonly the case with the sweet juices of fruits and beer worts,
these substances become changed into ferments in the course of the
fermentation induced by the yeast, and, being superfluous, so to speak,
for that particular process, they remain entire at the end, and may be
collected for use in other operations.

Upon this principle is founded the increased production of yeast, and
the manufacture of what has been called _artificial barm_, in which the
fermentation is conducted chiefly with a view to the formation of yeast.
To the fermenting mass, those kinds of meal are added which abound in
albumen and gluten, as barley, beans, or wheat, for instance; and the
process is similar to the production of a great lump of leaven, from the
action of a small piece of it upon dough. The following prescription
will illustrate this subject. Take three ounces of bean flour, add to it
five quarts of boiling water, and boil the mixture for half an hour.
Pour the decoction into a vessel, and stir into it, while hot, 56 ounces
of wheaten flour. After the mixture cools to the temperature of 54° F.,
add to it about two quarts of beer barm, stirring the whole well
together. About 24 hours after the commencement of the fermentation,
incorporate with the mixture 112 ounces of barley or bean flour, till it
becomes a uniform dough, which must be thoroughly kneaded, rolled out
into cakes about an inch thick, and cut into pieces of the size of a
dollar. These cakelets must be dried upon laths in the sun in favourable
weather, and then put up in a dry situation. For use, one of these discs
is to be broken into pieces, laid in warm water, and set in a warm place
during 12 hours. The soft mass will then serve the purpose of beer
yeast.

Or we may mix equal parts of barley malt, wheat malt, and crushed rye,
pour water at the temperature of 122° F. over them into a tub till it
stand a span above their surface; then stir well together, and allow the
whole to remain at rest for a few hours, till it cools to about 65° F.
We must now add for each pound of the mingled meals, a quarter of an
ounce of beer barm. The tub must be then covered, and preserved at a
temperature of 63° F. The husks, as they begin to rise to the surface,
in consequence of the fermentation, must be taken off, and squeezed
through a cloth over the vessel. When the meal comes afterwards to
subside to the bottom, the whole must be strained through a canvas bag,
and freed from the superfluous moisture by squeezing. The bag with its
doughy mass must next be surrounded with dry ashes, to remove the
remaining humidity, and to arrest any further fermentation. This
consistent ferment may be used instead of beer yeast.

It is difficult to prepare an artificial yeast without barm. The best
process for this purpose is the following. Take five parts of honey, one
part of powdered tartar, and sixteen parts of wheat or barley malt, stir
the whole in water of the temperature of 122° F., and place in a
fermenting heat; when the yeast will, as usual, be eliminated.

The change which gluten or vegetable albumen undergoes in the different
kinds of meal, when it becomes a ferment, consists apparently in an
oxidation, since analysis shows that this ferment contains more oxygen
than gluten does.

It has been already stated that yeast in its liquid condition readily
putrefies, and becomes altogether useless for the process of
fermentation. In order to preserve it for some time, it must be dried to
such a degree as to resist spontaneous decomposition without losing its
fermentative faculty; but completely dried yeast loses that property,
and does not recover it by being again moistened. Beer barm may be dried
after being washed several times with cold water, till the last quantity
comes off clear; but the insoluble portion must be allowed to settle
fully before the water is poured away from it. The residuum being freed
as much as possible from water, by drainage and pressure between flannel
cloths, is to be dried in the shade by a current of warm air as quickly
as possible, with the aid of frequent turning over. It must be
afterwards kept in dry earthen vessels. Yeast may also be preserved a
short time in activity by being kneaded with as much barley or wheat
flour as it can take up without losing the doughy consistence. Dried
yeast has, however, always an impaired activity. The easiest and most
certain method of preserving yeast in its primitive power, is by mixing
it, after pressure in flannel, with as much pulverized sugar as will
render it dry, and putting up the mixture in air-tight vessels. The
fermentative power of yeast is destroyed by the following means: 1. as
already stated, by making it completely dry either by the evaporation of
the water, or its abstraction by alcohol; 2. by boiling, which if
continued for ten minutes renders yeast quite inoperative; 3. by the
action of such substances as dissolve out its essential constituents; by
alkalis, for instance, since the particles of yeast seem to be operative
only in their insoluble granular state; 4. by such substances as form
combinations with it, and thereby either alter its nature, or at least
increase the cohesion of its constituent parts, so that they can no
longer operate upon sweet liquors by the decomposing affinity of its
ultimate particles. Such bodies are the acids, especially the mineral
ones, tannin and most salts, particularly the metallic, which unite with
the yeast into new compounds. The volatile oils which contain sulphur
exercise the same paralyzing influence upon yeast.

The circumstances which promote, and are necessary to, the vinous
fermentation are, conformably to the above views, the following:--1. The
presence of the proper quantity of active yeast, and its proper
distribution through the worts. If in the course of a slack fermentation
the yeast subsides to the bottom, the intestine motions cease entirely,
but they may be excited anew by stirring up the ingredients, or rousing
the tun, as the brewers say. 2. A certain degree of warmth, which should
never be less than 51° F., nor more than 86°; the temperature of from
68° to 77° being the most propitious for the commencement and progress
of fermentation. When other circumstances are the same, the rapidity of
the fermentation is proportional to the temperature within certain
limits, so that by lowering it, the action may be moderated at pleasure.
3. The fermentation proceeds the better and more equably the greater the
mass of fermenting liquor, probably on account of the uniformly high
temperature, as well as the uniform distribution of the active particles
of the yeast by the greater energy of the intestine movements. 4. The
saccharine solution must be sufficiently diluted with water; when too
much concentrated it will not ferment. Hence very sweet musts furnish
wines containing much undecomposed sugar. For a complete fermentative
action, one part of sugar should be dissolved in ten parts of water.

Fermentation maybe tempered or stopped: 1. by those means which render
the yeast inoperative, particularly by the oils that contain sulphur, as
oil of mustard; as also by the sulphurous and sulphuric acids. The
operation of the sulphurous acid in obstructing the fermentation of must
consists partly, no doubt, in its absorbing oxygen, whereby the
elimination of the yeasty particles is prevented. The sulphurous acid,
moreover, acts more powerfully upon fermenting liquors that contain
tartar, as grape juice, than sulphuric acid. This acid decomposes the
tartaric salts, and, combining with their bases, sets the vegetable acid
free, which does not interfere with the fermentation; but the sulphurous
acid operates directly upon the yeast: 2. by the separation of the
yeast, either with the filter or by subsidence: 3. by lowering the
temperature to 45° F. If the fermenting mass become clear at this
temperature, and be drawn off from the subsided yeast, it will not
ferment again, though it should be heated to the proper pitch.

The products of vinous fermentation are carbonic acid gas, and alcohol;
of which the former escapes during the process, except in the case of
the sparkling wines, like champaign, that are partially fermented in
close vessels. The alcohol remains in the fermented liquor. 100 parts of
sugar afford by complete decomposition nearly 50 parts of alcohol.
According to Thenard, 100 parts of sugar are converted into 46·8 parts
of carbonic acid, and 49·38 of alcohol; besides 3·82 parts of carbon
otherwise employed, which the sugar contained, above what is present in
the former two products. This chemist found in the fermented liquor 4
per cent. of an extractive matter, soluble in water, and having an
acidulous reaction, to whose formation, probably, that excess of carbon
may be necessary. In what way the action of the yeasty particles upon
the saccharine substance is carried on in the vinous fermentation, or
what may be the interior working of this process, is not accurately
understood. The quantitative relation of the carbonic acid and alcohol
to the sugar is pretty well made out; but the determination of the
ultimate principles of the ferment itself, before and after the vinous
change, and of the residuum dissolved in the fermented liquor, has not
been well ascertained. It is probable that the yeast undergoes in the
process a similar decomposition to that of the putrefactive, and that
its elementary constituents enter into new combinations, and abstract so
much carbon and hydrogen from the sugar, that the remainder, amounting
to 96 per cent. of the whole, may constitute one atom of alcohol and one
of carbonic acid.

3. _The slimy or glutinous fermentation._--This process takes place in
weak solutions of sugar, at ordinary fermenting temperatures, where,
from defect of good yeast, the vinous fermentation cannot proceed. In
such circumstances from one part of sugar, one third part of gum is
formed. According to Desfosses however, 100 parts of sugar afford 109·48
of gum or slime. This is formed when one part of sugar is dissolved in
twenty parts of water, which had been previously boiled with washed barm
or gluten, and then filtered. The process proceeds slowly and quietly,
equally well in close vessels, as with contact of air, and continues at
ordinary temperatures about 12 days; but it goes on more rapidly and
completely at the heat of from 77° to 86° F. A small quantity of
hydrogen and carbonic acid gas is disengaged, in the proportion of two
to one by volume. The fermented liquor becomes turbid, and assumes a
tough thready appearance, like a decoction of linseed. A small addition
of sulphuric or sulphurous acid, of muriatic acid and alum, or of
tannin, impedes this species of fermentation; because these substances
combine, as in the vinous fermentation, with the ferment into an
insoluble precipitate, unsusceptible of further change. In many wines,
especially when bottled, this slimy fermentation occurs, and occasions
their ropiness, which may be best remedied or prevented by the addition
of as much tannin as will precipitate the dissolved mucous matter. This
species of fermentation attacks very rapidly the rinsing waters of the
sugar refiner, which always contain some fermentative gluten. A little
alum is the best preventative in this case, because it precipitates the
dissolved ferment.

4. _The acetous or sour fermentation._--In this process, alcohol, more
or less dilute, is resolved into water and vinegar, in consequence of
the operation of the ferment; oxidizement of the alcohol being effected
by the oxygen of the atmospherical air. The requisites of this process
have been already detailed under the article ACETIC ACID. They are the
presence of atmospherical air; alcohol diluted to a certain degree with
water ferment or yeast, and a temperature above 66° F. The most active
ferments are such substances as have already passed into the acetous
state; hence vinegar, especially when it contains some yeasty particles,
or is combined with porous and spongy bodies, so as to multiply its
points of contact with the vinous liquor, is particularly powerful.
Common yeast may also be employed for vinegar ferments, if it be imbued
with a little vinegar, with leaven, crusts of bread soaked in vinegar,
the stalks and husks of grapes, sawdust and shavings of beech or oak
impregnated with vinegar, or the slimy sediment of vinegar casks called
_mother_; all of which operate as ferments chiefly in consequence of the
vinegar which they contain. The inside shavings of the staves of vinegar
tuns act on the same principle.

The acetous fermentation may, moreover, go on along with the vinous in
the same liquor, when this contains sugar as well as alcohol. Whilst the
acidification of the alcohol is effected by the absorption of oxygen
from the atmosphere, the sugar becomes alcohol with disengagement of
carbonic acid, and then passes into vinegar. Since most liquors intended
for making vinegar, such as wine, juices of fruits, ales, &c., contain
still a little sugar, they disengage always a little carbonic acid.
Besides spirits, some other substances, such as gum, the mucilage of
plants, and starch paste, directly ferment into vinegar. Sugar also
seems to be convertible into vinegar without any vinous change. The
albuminous matter of potato juice, precipitated by vinegar, serves as a
proper ferment for that purpose, when added in its moist state to weak
syrup. 5. See PUTREFACTION.

Mr. William Black, in his treatise on Brewing, has, with much ingenuity
and apparent truth, endeavoured to show that the process of fermentation
is strongly influenced by electricity, not only that of the atmosphere,
as has been long known from the circumstance of beer and wine becoming
speedily sour after thunderstorms, but the voltaic, produced by electric
combinations of metals in the fermenting tuns. He therefore recommends
these tuns to be made with as little metallic work as possible, and to
be insulated from the floor of the brewhouse. For the propriety of this
advice he adduces some striking examples. Wort which had become
stationary in its fermentation, on being pumped out of square gyles
imbedded in the floor, into casks placed upon wooden stillions, began
immediately to work very well, and gained about 6 degrees of attenuation
while throwing off its yeast. From the stagnation of the process in the
gyles, he had in the morning predicted an approaching thunderstorm,
which accordingly supervened in the course of the evening. In further
support of his views he instances the fact, that, in dairies where the
milk is put into porcelain vessels, and placed upon wooden shelves, it
is seldom injured by lightning; but when contained in wooden or leaden
vessels, and placed upon the ground, it almost invariably turns sour in
thundery weather. His general conclusion is “that the preservation or
destruction of beer depends upon electricity; and the most certain mode
of preservation is to insulate as much as possible, both the squares and
all other utensils or vessels connected with the brewing or storing of
beer.”

Mr. Black further considers that unsoundness of worts is often the
result of electricity excited between the mash tun and the copper.

Why is beer liable to get spoiled in thunder storms, though apparently
well insulated in glass bottles?

I shall conclude this article with Mr. Black’s description of the
phenomena of beer fermentation. In every regular process there are five
distinct stages. In the first we see a substance like cream forming all
round the edges of the gyle tun; which extends towards the centre until
the whole is creamed over, constituting the first change. Next a fine
curl appears like cauliflower, which also spreads over the square
surface, and according to the strength and appearance of this curl, the
quality of the fermentation may be predicated. This he calls the second
stage. What is technically called the _stomach_ or vinous vapour now
begins to be smelt, and continues to gain strength till the process is
concluded. From the vinous energy of this odour, and the progressive
attenuation of the wort, the vigour of the fermentation may be inferred.
The experienced brewer is much guided in his operations by the
peculiarity of this effluvium. The third change is when the cauliflower
or curling top rises to a fine rocky or light yeasty head; and when this
falls down, the fourth stage has arrived. Finally the head should rise
to what is called close yeasty, having the appearance of yeast all over.
About this period the gas becomes so powerful as to puff up occasionally
in little bells or bladders about the size of a walnut, which
immediately break. The bells should appear bright and clear. If they be
opaque or whey coloured, there is some unsoundness in the wort. The
great point is to add just so much yeast as to carry the fermentation
completely through these five changes at the regular periods.


FERROCYANATE, or, more correctly, FERROCYANIDE. (_Ferrocyanure_, Fr.;
_Eisencyanid_, Germ.) Several compounds of cyanogen and metals possess
the property of uniting together into double cyanides; of which there
are none so remarkable in this respect, as the protocyanide of iron.
This appears to be capable of combining with several simple cyanides,
such as that of potassium, sodium, barium, strontium, calcium, and
ammonium. The only one of these double cyanides of any importance in
manufactures is the first, which is described under its commercial name,
PRUSSIATE OF POTASH.


FERROPRUSSIATES; another name for Ferrocyanides.


FIBRE, VEGETABLE, called also LIGNINE; (_Ligneux_, Fr.;
_Pflanzen-faserstoff_, Germ.) is the most abundant and general
ingredient of plants, existing in all their parts, the root, the leaves,
the stem, the flowers, and the fruit; amounting in the compact wood to
97 or 98 per cent. It is obtained in a pure state by treating saw-dust
successively with hot alcohol, water, dilute muriatic acid, and weak
potash lye, which dissolve, first, the resinous; second, the extractive,
and saline matters; third, the carbonate and phosphate of lime; and,
lastly, any residuary substances. Ligneous fibres, such as saw-dust,
powdered barks, straw, hemp, flax, linen, and cotton cloth, are
convertible by the action of strong sulphuric acid into a gummy
substance analogous to _dextrine_, and a sugar resembling that of the
grape.

If we put into a glass mortar 24 parts, by weight, of dry old cordage,
chopped small, and sprinkle over it 34 parts of sulphuric acid, by
degrees, so as to avoid heating the mixture, while we constantly stir
it; and if, in a quarter of an hour, we triturate the mass with a glass
pestle, the fibres will disappear without the disengagement of gas. A
tenacious mucilage will be produced, almost entirely soluble in water.
The gum being thus formed, may be separated from the acid by dilution
with water, and addition of the requisite quantity of chalk; then
straining the saturated liquid through linen cloth, concentrating it by
evaporation, throwing down any remaining lime by oxalic acid, filtering
anew, and mixing the mucilage with alcohol in great excess, which will
take up the free acid, and throw down the gum. From 24 parts of hemp
fibres thus treated, fully 24 parts of a gummy mass may be obtained,
containing, however, probably some water.

When, instead of saturating the diluted acid paste with chalk, we boil
it for 10 hours, the gummy matter disappears, and is replaced by sugar,
which may be purified without any difficulty, by saturation with chalk,
filtration, and evaporation to the consistence of syrup. In 24 hours
crystallization begins, and, in 2 or 3 days, a concrete mass of grape
sugar is formed; which needs merely to be pressed strongly between old
linen cloths doubled, and then crystallized a second time. If this syrup
be treated with bone black, a brilliant white sugar will be procured. 20
parts of linen rags yield 23 of good sugar. _Braconnot_. Guerin got
87-1/2 of dry sugar from 100 parts of rags, treated with 250 of
sulphuric acid. See WOOD.


FIBRINE, (Eng. and Fr.; _Thierischer Faserstoff_, Germ.) constitutes the
principal part of animal muscle; it exists in the chyle, the blood, and
may be regarded as the most abundant constituent of animal bodies. It
may be obtained in a pure state by agitating or beating new drawn blood
with a bundle of twigs, when it will attach itself to them in long
reddish filaments, which may be deprived of colour by working them with
the hands under a streamlet of cold water, and afterwards freed from any
adhering grease by digestion in alcohol or ether.

Fibrine, thus obtained, is solid, white, flexible, slightly elastic,
insipid, inodorous, denser than water, but containing 4 fifths of its
weight of it, and without action on litmus. When dried, it becomes
semi-transparent, yellowish, stiff, and brittle: water restores its
softness and flexibility. 100 parts of fibrine consist of 53·36 carbon,
19·68 oxygen, 7·02 hydrogen, and 19·31 azote. As the basis of flesh, it
is a very nutritious substance, and is essential to the sustenance of
carnivorous animals.


FILE (_Lime_, Fr.; _Feile_, Germ.), is a well known steel instrument,
having teeth upon the surface for cutting and abrading metal, ivory,
wood, &c.

When the teeth of these instruments are formed by a straight sharp-edged
chisel, extending across the surface, they are properly called files;
but when by a sharp-pointed tool, in the form of a triangular pyramid,
they are termed rasps. The former are used for all the metals, as well
as ivory, bone, horn, and wood; the latter for wood and horn.

Files are divided into two varieties, from the form of their teeth. When
the teeth are a series of sharp edges, raised by the flat chisel,
appearing like parallel furrows, either at right angles to the length of
the file, or in an oblique direction, they are termed _single cut_. But
when these teeth are crossed by a second series of similar teeth, they
are said to be _double cut_. The first are fitted for brass and copper,
and are found to answer better when the teeth run in an oblique
direction. The latter are suited for the harder metals, such as cast and
wrought iron and steel. Such teeth present sharp angles to the
substance, which penetrate it, while single cut files would slip over
the surface of these metals. The double cut file is less fit for filing
brass and copper, because its teeth would be very liable to become
clogged with the filings.

Files are also called by different names according to their various
degrees of fineness. Those of extreme roughness are called rough; the
next to this is the bastard cut; the third is the second cut; the
fourth, the smooth; and the finest of all, the dead smooth. The very
heavy square files used for heavy smith-work, are sometimes a little
coarser than the rough; they are known by the name of rubbers.

Files are also distinguished from their shape, as flat, half-round,
three-square, four-square, and round. The first are sometimes of uniform
breadth and thickness throughout, and sometimes tapering. The cross
section is a parallelogram. The half-round is generally tapering, one
side being flat, and the other rounded. The cross section is a segment
of a circle, varying a little for different purposes, but seldom equal
to a semi-circle. The three-square generally consists of three equal
sides, being equilateral prisms, mostly tapering; those which are not
tapering are used for sharpening the teeth of saws. The four-square has
four equal sides, the section being a square. These files are generally
thickest in the middle, as is the case with the smith’s rubber. In the
round file, the section is a circle, and the file generally conical.

The heavier and coarser kinds of files are made from the inferior marks
of blistered steel. Those made from the Russian iron, known by the name
of old sable, called from its mark CCND, are excellent. The steel made
from the best Swedish iron, called hoop L or Dannemora, makes the finest
Lancashire files, for watch and clock makers; a manufacture for which
the house of Stubbs in Warrington is celebrated.

The steel intended for files is more highly converted than for other
purposes, to give them proper hardness. It should however be
recollected, that if the hardness be not accompanied with a certain
degree of tenacity, the teeth of the file break, and do but little
service.

Small files are mostly made of cast steel, which would be the best for
all others, if it were not for its higher price. It is much harder than
the blistered steel, and from having been in the fluid state, is
entirely free from those seams and loose parts so common to blistered
steel, which is no sounder than as it comes from the iron forge before
conversion.

The smith’s rubbers are generally forged in the common smith’s forge,
from the converted bars, which are, for convenience, made square in the
iron before they come into this country. The files of lesser size are
made from bars or rods, drawn down from the blistered bars, and the cast
ingots, and known by the name of tilted steel.

The file-maker’s forge consists of large bellows, with coak as fuel. The
anvil-block, particularly at Sheffield, is one large mass of mill-stone
girt. The anvil is of considerable size, set into and wedged fast into
the stone; and has a projection at one end, with a hole to contain a
sharp-edged tool for cutting the files from the rods. It also contains a
deep groove for containing dies or bosses, for giving particular forms
to the files.

The flat and square files are formed entirely by the hammer. One man
holds the hot bar, and strikes with a small hammer. Another stands
before the anvil with a two-handed hammer. The latter is generally very
heavy, with a broad face for the large files. They both strike with such
truth as to make the surface smooth and flat, without what is called
hand-hammering. This arises from their great experience in the same kind
of work. The expedition arising from the same cause is not less
remarkable.

The half-round files are made in a boss fastened into the groove above
mentioned. The steel being drawn out, is laid upon the rounded recess,
and hammered till it fills the die.

The three-sided files are formed similarly in a boss, the recess of
which consists of two sides, with the angle downwards. The steel is
first drawn out square, and then placed in a boss with an angle
downwards, so that the hammer forms one side, and the boss two. The
round files are formed by a swage similar to those used by common
smiths, but a little conical.

The file-cutter requires an anvil of a size greater or less,
proportioned to the size of his files, with a face as even and flat as
possible. The hammers weigh from one to five or six pounds. The chisels
are a little broader than the file, sharpened to an angle of about 20
degrees. The length is just sufficient for them to be held fast between
the finger and thumb, and so strong as not to bend with the strokes of
the hammer, the intensity of which may be best conceived by the depth of
the impression. The anvil is placed in the face of a strong wooden post,
to which a wooden seat is attached, at a small distance below the level
of the anvil’s face. The file is first laid upon the bare anvil, one end
projecting over the front, and the other over the back edge of the same.
A leather strap now goes over each end of the file, and passes down upon
each side of the block to the workman’s feet, which, being put into the
strap on each side, like a stirrup, holds the file firmly upon the anvil
as it is cut. While the point of the file is cutting, the strap passes
over one part of the file only, the point resting upon the anvil, and
the tang upon a prop on the other side of the strap. When one side of
the file is single cut, a fine file is run slightly over the teeth, to
take away the roughness; when they are to be double cut, another set of
teeth is cut, crossing the former nearly at right angles. The file is
now finished upon one side, and it is evident that the cut side cannot
be laid upon the bare anvil to cut the other. A flat piece of an alloy
of lead and tin is interposed between the toothed surface and the anvil,
while the other side is cut, which completely preserves the side already
formed. Similar pieces of lead and tin, with angular and rounded
grooves, are used for cutting triangular and half-round files.

Rasps are cut precisely in the same way, by using a triangular punch
instead of a flat chisel. The great art in cutting a rasp is to place
every new tooth as much as possible opposite to a vacancy.

Many abortive attempts have been made to cut the teeth of files by
machinery. The following plan, for which a patent was obtained by Mr.
William Shilton, of Birmingham, in April 1833, is replete with ingenious
mechanical resources, and deserves to succeed.

The blanks of steel for making the files and rasps, are held in a pair
of clamps in connexion with a slide, and are moved forward at intervals
under the head of the tilt hammer which carries the tool; the distance
which the blank is to be advanced at every movement being dependent upon
the required fineness or coarseness of the cut of the file, which
movement is effected and regulated by a rack and pinion, actuated by a
pall and ratchet wheel, or the movement may be produced by any other
convenient means.

When the machine is employed for cutting or indenting the teeth of
rasps, the cutting tool being pointed and only producing one tooth at a
blow, the tilt hammer carrying the tool must be made to traverse at
intervals across the width of the blank piece of steel from one edge to
the other and back again; the blank being advanced in length only when
the hammer has produced the last cut or tooth toward either edge of the
rasp.

In order to render this invention better understood, two views of the
apparatus for producing the cross-cut or teeth of the files, are given.

[Illustration: 384* 385]

_Fig._ 384*. is an elevation of the upper part of the file-cutting
machine, as seen on one side; _fig._ 385. is a plan or horizontal view,
as the machine appears on the top.

_a_, is the head of the tilt hammer placed in the end of the lever _b_,
which is mounted on an axle _c_, turning in proper bearings in the frame
work of the machine; _d_, is the tilt wheel mounted on another axle _s_,
also turning in bearings on the frame work of the machine, and having
any required number of projections or tappets upon it for depressing the
tail or shorter end of the hammer or tilt lever _b_.

The tilt wheel _d_, receives its rotatory motion from the toothed wheel
_f_, mounted upon the same axle, and it takes into geer with a pinion
_g_, upon the main shaft _h_, which is actuated by a band passed from
any first mover to the rigger on its end, or in any other convenient
manner. The bed upon which the blank piece of steel bears is marked _i_.
This bed is firmly supported upon masonry placed upon proper sleepers:
_j_, is one of the blank pieces of steel under operation, and is shown
secured in the pair of jaws or holding clamps _k_, mounted on centre
pins in the slide _l_, _fig._ 385.; which slide is held down by a spring
and slide beneath, and is moved backwards and forwards in the machine
upon the (v) edges _m_, _m_, of the frame, by means of the rack _n_, and
its pinion; the latter being mounted upon the axle of the ratchet wheel
_p_, and which ratchet wheel is made to turn at intervals by means of
the pall _q_, upon the end of the lever _r_, _fig._ 385. This lever is
depressed, after every cut has been effected upon the blank by means of
the teeth or tappets of the wheel _s_, coming in contact with the
inclined plane _t_, upon the lever _r_. The tappet wheel _s_, is mounted
upon the end of the axle _e_, of the tilt wheel, and consequently
revolves with it, and by depressing the lever _r_, every time that a
tooth passes the inclined plane _t_, the click _q_, is made to drive the
ratchet wheel _p_, and thereby the advancing movement of the blank is
effected after each blow of the tilt hammer.

There is a strong spring _u_, attached to the upper side of the tilt
hammer, its end being confined under an adjustable inclined plane _v_,
mounted in the frame _w_, which inclined plane can be raised or lowered
by its adjusting screws as required, to produce more or less tension of
the spring.

A similar spring is placed on the under side of the tilt hammer, to
raise and sustain the cutter or tool clear of the bed after every blow,
and in conjunction with safety holders or catchers, to counteract any
vibration or tendency the spring _u_, may have to cause the hammer to
reiterate the blow.

The end of the lower spring acts on an inclined plane, mounted in the
frame _w_, which has an adjusting screw similar to _v_, to regulate the
tension of the spring.

In case the under spring should raise, that is, return the hammer, with
sufficient force or velocity to cause the top spring _u_, to reiterate
the blow, the ends of the safety holders or catchers are made to move
under and catch the tail of the lever _b_, immediately on its being
raised by the under springs, which is effected by the following
means:--The holders are mounted upon a plate or carriage 1, _fig._ 384.,
which turns upon a small pin or axle mounted in the ears of a cross bar;
the upper ends of the holders are kept inclined towards the tail of the
tilt hammer by means of a spring fixed to the cross bar, and which acts
upon one end of the plate or carriage 1.

In order that the holders may be removed out of the way of the tail of
the hammer _b_, when the tilt wheel is about to effect a blow, the tooth
of the tilt wheel which last acted upon the hammer comes in contact with
an inclined plane fixed on the plate or carriage 1, and by depressing
that end of the plate, causes the upper ends of the holders to be
withdrawn from under the tail of the hammer _b_. The tilt wheel
continuing to revolve, the next tooth advances, and depresses the tail
of the hammer, but before it leaves the tail of the hammer, the tooth
last in operation will have quitted the inclined plane and allowed the
spring to return the holders into their former position. After the tooth
has escaped from the tail of _b_, the hammer will immediately descend
and effect the blow or cut on the blank, and as the tail of the hammer
rises, it will come in contact with the inclined planes at the upper
ends of the holders, and force them backwards; and as soon as the tail
of the hammer has passed the top of the holders, the spring will
immediately force the holders forward under the tail of the hammer, and
prevent the hammer rising again until the next tooth of the tilt wheel
is about to depress the end of the hammer, when the same movements of
the parts will be repeated, and the machine will continue in operation
until a sufficient length of the blank of steel (progressively advanced
under the hammer) has been operated upon, when it will be thrown out of
geer by the following means:--

Upon the sliding bar 6, there is placed an adjustable stop, against
which the foremost end of the slide _l l_, _fig._ 385. comes in contact,
as it is moved forward by the rack _n_, and its pinion. The sliding bar
6, is connected at its left end to the bent lever 8, the other end of
this lever being formed into a forked arm, which embraces a clutch upon
the main shaft, and as the slide _l_ continues to advance, it will come
in contact with a stop; and when it has brought a sufficient length of
the blank pieces of steel under the operation of the cutting tool, the
slide _l_, in its progress, will have moved that stop and the bar 6
forward, and that bar, by means of the bent lever 8, will withdraw the
clutch on the main shaft, from locking into the boss of the fly-wheel,
and consequently stop the further progress of the machine; the rigger
and fly-wheel turning loosely upon the main shaft.

The cut file can now be removed from out of the clamps, and reversed to
cut the other side, or another blank piece put in its place; and after
throwing back the pall _q_ of the ratchet wheel _p_, the slide _l_, and
with it the fresh blank may be moved back into the machine by turning
the winch handle, on the axle of the ratchet wheel _p_, the reverse way,
which will turn the pinion backwards, and draw back the rack _n_,
without affecting any other parts of the machine; and on moving back the
bar 6, by the handle 11, placed on the stop, the clutches will be thrown
into geer again, and the machine proceed to cut the next blank.

When the blanks have been thus cut on one side, and are reversed in the
machine to form the teeth upon the other side, there should be a piece
of lead placed between the blank and the bed to protect the fresh cut
teeth.

It will be seen that the position of the stop upon the bar 6, will
determine the length or extent of the blank piece of steel which shall
be cut or operated upon; and in order that the progressive movement of
the blanks under the cutting tool may be made to suit different degrees
of fineness or coarseness of the teeth (that is the distance between the
cuts), there is an adjusting screw upon the lever _r_, the head of which
screw stops against the under side of an ear projecting from the
frame-work, and thereby determines the extent of the motion of the lever
_r_, when depressed by the tappets of the wheel s, acting upon the
inclined plane _t_, consequently determining the number of teeth the
ratchet wheel _p_ shall be moved round by the pall _q_; and hence the
extent of motion communicated by the rack and pinion to the slide _l_,
and the blank _j_, which regulates the distance that the teeth of the
file are apart, and the lever _r_ is forced upwards by a spring pressing
against its under side.

It will be perceived that the velocity of the descent of the hammer, and
consequently the force of the blow, may be regulated by raising or
lowering the inclined plane _v_ of the spring _u_; and in order to
accommodate the bed upon which the blanks rest to the different
inclinations they may be placed at, that part of the bed is formed of a
semi-globular piece of hardened steel, which fits loosely into a similar
concavity in the bed _r_, and is therefore capable of adjusting itself,
so that the blanks shall be properly presented to the cutting tool, and
receive the blow or cut in an equal and even manner; or the piece of
steel may be of a conical shape, and fit loosely in a similar shaped
concavity.

There are guides 16, placed on the top of the bed _i_, for the purpose
of keeping the blanks in their proper position towards the cutting tool,
and these can be regulated to suit blanks of any width, by turning the
right and left handed screw 17. There is also another adjustable stop on
the jaws or clamps _k_ which serves as a guide when placing the blanks
within the jaws: and 19 is a handle or lever for raising the clamps when
required, which has a weight suspended from it for the purpose of
keeping down the blanks with sufficient pressure upon the bed.

The cutting tool in the face of the hammer, can be placed at any
required angle or inclination with the blank, it being secured in the
head of the hammer by clamps and screws. In cutting fine files a screw
is employed in preference to the rack and pinion, for advancing the
slide _l_, and the blank piece of steel in the machine.

_Hardening of files._--This is the last and most important part of file
making. Whatever may be the quality of the steel, or however excellent
the workmanship, if it is not well hardened all the labour is lost.

Three things are strictly to be observed in hardening; first, to prepare
the file on the surface, so as to prevent it from being oxidated by the
atmosphere when the file is red hot, which effect would not only take
off the sharpness of the tooth, but render the whole surface so rough
that the file would, in a little time, become clogged with the substance
it had to work. Secondly, the heat ought to be very uniformly red
throughout, and the water in which it is quenched, fresh and cold, for
the purpose of giving it the proper degree of hardness. Lastly, the
manner of immersion is of great importance, to prevent the files from
warping, which in long thin files is very difficult.

The first object is accomplished by laying a substance upon the file,
which when it fuses, forms as it were, a varnish upon the surface,
defending the metal from the action of the oxygen of the air. Formerly
the process consisted in first coating the surface of the file with ale
grounds, and then covering it over with pulverized common salt, (muriate
of soda.) After this coating became dry, the files were heated red hot,
and hardened; after this, the surface was lightly brushed over with the
dust of cokes, when it appeared white and metallic, as if it had not
been heated. This process has lately been improved, at least so far as
relates to the economy of the salt, which from the quantity used, and
the increased thickness, had become a serious object. Those who use the
improved method are now consuming about one fourth the quantity of salt
used in the old method. The process consists in dissolving the salt in
water to saturation, which is about three pounds to the gallon, and
stiffening it with ale grounds, or with the cheapest kind of flour, such
as that of beans, to about the consistence of thick cream. The files
require to be dipped only into this substance, and immediately heated
and hardened. The grounds or the flour are of no other use, than to give
the mass consistence, and by that means to allow a larger quantity of
salt to be laid upon the surface. In this method, the salt forms
immediately a firm coating. As soon as the water is evaporated, the
whole of it becomes fused upon the file. In the old method the dry salt
was so loosely attached to the file, that the greatest part of it was
rubbed off into the fire, and was sublimed up the chimney, without
producing any effect.

The carbonaceous matter of the ale grounds is supposed to have some
effect in giving hardness to the file, by combining with the steel, and
rendering it more highly carbonated. It will be found, however, upon
experiment, that vegetable carbon does not combine with iron, with
sufficient facility to produce any effect, in the short space of time a
file is heating, for the purpose of hardening. Some file makers are in
the habit of using the coal of burnt leather, which doubtless produces
some effect; but the carbon is generally so ill prepared for the
purpose, and the time of its operation so short, as to render the result
inconsiderable. Animal carbon, when properly prepared and mixed, with
the above hardening composition, is capable of giving hardness to the
surface even of an iron file.

This carbonaceous matter may be readily obtained from any of the soft
parts of animals, or from blood. For this purpose, however, the refuse
of shoemakers and curriers is the most convenient. After the volatile
parts have been distilled over, from an iron still, a bright shining
coal is left behind, which, when reduced to powder, is fit to mix with
the salt. Let about equal parts, by bulk, of this powder, and muriate of
soda be ground together, and brought to the consistence of cream, by the
addition of water. Or mix the powdered carbon with a saturated solution
of the salt, till it become of the above consistence. Files which are
intended to be very hard, should be covered with this composition,
previous to hardening. All files intended to file iron or steel,
particularly saw files, should be hardened with the aid of this mixture,
in preference to that with the flour or grounds. Indeed, it is probable,
that the carbonaceous powder might be used by itself, in point of
economy, since the ammonia or hartshorn, obtained by distillation, would
be of such value as to render the coal of no expense. By means of this
method the files made of iron, which, in itself, is unsusceptible of
hardening, acquire a superficial hardness sufficient for any file
whatever. Such files may, at the same time, be bent into any form; and,
in consequence, are particularly useful for sculptors and die-sinkers.

The next point to be considered is the best method of heating the file
for hardening. For this purpose a fire, similar to the common smiths’
fire, is generally employed. The file is held in a pair of tongs by the
tang, and introduced into the fire, consisting of very small cokes,
pushing it more or less into the fire for the purpose of heating it
regularly. It must frequently be withdrawn with the view of observing
that it is not too hot in any part. When it is uniformly heated, from
the tang to the point, of a cherry red colour, it is fit to quench in
the water. At present an oven, formed of fire-bricks, is used for the
larger files, into which the blast of the bellows is directed, being
open at one end, for the purpose of introducing the files and the fuel.
Near to the top of the oven are placed two cross bars, on which a few
files are placed, to be partially heating. In the hardening of heavy
files, this contrivance affords a considerable saving, in point of time,
while it permits them also to be more uniformly and thoroughly heated.

After the file is properly heated for the purpose of hardening, in order
to produce the greatest possible hardness, it should be cooled as soon
as possible. The most common method of effecting this is by quenching it
in the coldest water. Some file-makers have been in the habit of putting
different substances in their water, with a view to increase its
hardening property. The addition of sulphuric acid to the water was long
held a great secret in the hardening of saw files. After all, however,
it will be found, that clear spring water, free from animal and
vegetable matter, and as cold as possible, is the best calculated for
hardening files of every description.

In quenching the files in water, some caution must be observed. All
files, except the half-round, should be immersed perpendicularly, as
quickly as possible, so that the upper part shall not cool. This
management prevents the file from warping. The half-round file must be
quenched in the same steady manner; but, at the same time that it is
kept perpendicular to the surface of the water, it must be moved a
little horizontally, in the direction of the round side, otherwise it
will become crooked backwards.

After the files are hardened, they are brushed over with water, and
powdered cokes, when the surface becomes perfectly clean and metallic.
They ought also to be washed well in two or three clean waters, for the
purpose of carrying off all the salt, which, if allowed to remain, will
be liable to rust the file. They should moreover be dipped into
lime-water, and rapidly dried before the fire, after being oiled with
olive oil, containing a little oil of turpentine, while still warm. They
are then finished.


FILLIGREE (_Filigrane_, Fr.; _Filigran_, or _Feine Drahtgeflecht_,
Germ.); is, as the last term justly expresses it, intertwisted fine
wire, used for ornamenting gold and silver trinkets. The wire is seldom
drawn round, but generally flat or angular; and soldered by gold or
silver solder with borax and the blowpipe. The Italian word,
_filigrana_, is compounded of _filum_ and _granum_, or granular
net-work; because the Italians, who first introduced this style of work,
placed small beads upon it.


FILTRATION (Eng. and Fr.; _Filtriren_, Germ.), is a process purely
mechanical, for separating a liquid from the undissolved particles
floating in it, which liquid may be either the useful part, as in
vegetable infusions, or of no use, as the washings of mineral
precipitates. The filtering substance may consist of any porous matter
in a solid, foliated, or pulverulent form; as porous earthen ware,
unsized paper, cloth of many kinds, or sand. The white blotting paper
sold by the stationers answers extremely well for filters in chemical
experiments, provided it be previously washed with dilute muriatic acid,
to remove some lime and iron that are generally present in it. Filter
papers are first cut square, and then folded twice diagonally into the
shape of a cornet, having the angular parts rounded off. Or the piece of
paper being cut into a circle, may be folded fan-like from the centre,
with the folds placed exteriorly, and turned out sharp by the pressure
of the finger and thumb, to keep intervals between the paper and the
funnel into which it is fitted, to favour the percolation. The diameter
of the funnel should be about three-fourths of its height, measured from
the neck to the edge. If it be more divergent, the slope will be too
small for the ready efflux of the fluid. A filter covered with the
sediment is most conveniently washed by spouting water upon it with a
little syringe. A small camel’s-hair paint brush is much employed for
collecting and turning over the contents in their soft state. Agitation
or vibration is of singular efficacy in quickening percolation, as it
displaces the particles of the moistened powders, and opens up the pores
which had become closed. Instead of a funnel, a cylindrical vessel may
be employed, having its perforated bottom covered with a disc of
filtering powder folded up at the edges, and made tight there by a wire
ring. Linen or calico is used for weak alkaline liquors; and flannels,
twilled woollen cloth, or felt-stuff for weak acid ones. These filter
bags are often made conical like a fool’s cap, and have their mouths
supported by a wooden or metallic hoop. Cotton wool put loose into the
neck of a funnel answers well for filtering oils upon the small scale.
In the large way, oil is filtered in conical woollen bags, or in a cask
with many conical tubes in its bottom, filled with tow or cotton wool.
Stronger acid and alkaline liquors must be filtered through a layer of
pounded glass, quartz, clean sand, or bruised charcoal. The alcarrhazas
are a porous biscuit of stone ware made in Spain, which are convenient
for filtering water, as also the porous filtering stone of Teneriffe,
largely imported into England at one time, but now superseded in a great
measure by the artificial filters patented under many forms, consisting
essentially of strata of gravel, sand, and charcoal powder.

It is convenient to render the filter self-acting, by accommodating the
supply of liquid to the rate of percolation, so that the pressure upon
the porous surface may be always equally great. Upon the small scale,
the lamp-fountain or bird’s-glass form so generally used for lamps, will
be found to answer.

[Illustration: 386 387]

_Fig._ 386. represents a glass bottle A, partly filled with the fluid to
be filtered, supported in the ring of a chemical stand, and having its
mouth inverted into the same liquor in the filter funnel. It is obvious,
that whenever this liquor by filtration falls below the lip of the
bottle, air will enter into it, let down a fresh supply to feed the
filter, and keep the funnel regularly charged. If larger quantities are
to be operated upon, the following apparatus may be employed. _Fig._
387. A B is a metallic vessel which may be made air-tight; C is the
under pipe provided with a stopcock R, for letting down the liquor into
the filter _a b_. The upper pipe _t_, through which the fluid is poured
by means of the funnel E, has also a stopcock which opens or shuts, at
the same time, the small side tube _u t_, through which, during the
entrance of the fluid, the air is let off from the receiver. A glass
tube _g_, shows the level of the liquor in the body of the apparatus. In
using it, the cock R must be first closed, and the cock S must be opened
to fill the receiver. Then the filter is set a going, by re-opening the
cock R, so as to keep the fluid in the filter upon a level with the
opening of the tube C. Both these pieces of apparatus are essentially
the same.

[Illustration: 388 389]

In many manufactures, self-acting filters are fed by the plumber’s
common contrivance of a ball-cock in which the sinking and rising of the
ball, within certain limits, serves to open or shut off the supply of
liquor, as it may be required or not. Dumont has adopted this expedient
for his system of filtering syrup through a stratum of granularly ground
animal charcoal or bone-black. _Fig._ 388. is a front view of this
apparatus with 4 filters C; and _fig._ 389. is a cross section. The
framework B supports the cistern A, in which the syrup is contained.
From it the liquor flows through the stop-cock _b_, and the
connection-tube _a_, into the common pipe _c_, which communicates, by
the short branch tubes _e_, with each of the four filters. The end of
the branch tube, which is inside of the filter tub, is provided with a
stopcock _d f_, whose opening, and thereby the efflux of the liquor from
the cistern through the tube _a_, is regulated by means of the
float-ball _g_. Upon the brickwork D the filter tub stands, furnished at
_h_ with a false bottom of zinc or copper pierced with fine holes;
besides which, higher up at _i_ there is another such plate of metal
furnished with a strong handle _k_, by which it may be removed, when the
bone-black needs to be changed. In the intervening space _l_, the
granular coal is placed. _o_ is the cover of the filter tub, with a
handle also for lifting it. One portion of it may be raised by a hinge,
when it is desired to inspect the progress of the filtration within. _m
m_ is a slender vertical tube, forming a communication between the
bottom part _h_, and the upper portion of the filter, to admit of the
easy escape of the air from that space, and from among the bone-black as
the syrup descends; otherwise the filtration could not go on. _p_ is the
stopcock through which the fluid collected in the space under _h_ is let
off from time to time into the common pipe _q_, _fig._ 388. _r_ is a
trickling channel or groove lying parallel to the tube _q_, and in
which, by means of a tube _s_, inserted at pleasure, the syrup is drawn
off in case of its flowing in a turbid state, when it must be returned
over the surface of the charcoal.

The celerity with which any fluid passes through the filter depends, 1.
upon the porosity of the filtering substance; 2. upon the pressure
exercised upon it; and 3. upon the extent of the filtering surface. Fine
powders in a liquor somewhat glutinous, or closely compacted, admit of
much slower filtration than those which are coarse and free; and the
former ought, therefore, to be spread in a thinner stratum and over a
more extensive surface than the latter, for equal effect; a principle
well exemplified in the working of Dumont’s apparatus, just described.

[Illustration: 390]

In many cases filtration may be accelerated by the increase of
hydrostatic or pneumatic pressure. This happens when we close the top of
a filtering cylinder, and connect it by a pipe with a cistern of fluid
placed upon a higher level. The pressure of the air may be rendered
operative also either by withdrawing it partially from a close vessel,
into which the bottom of the filter enters, or by increasing its density
over the top of the liquor to be filtered. Either the air pump or steam
may be employed to create a partial void in the receiver beneath the
filter. In like manner, a forcing pump or steam may be employed to exert
pressure upon the surface of the filtering liquor. A common syphon may,
on the same principle, be made a good pressure filter, by making its
upper leg trumpet-shaped, covering the orifice with filter paper or
cloth, and filling the whole with liquor, the lower leg being of such
length so as to create considerable pressure by the difference of
hydrostatic level. This apparatus is very convenient either on the small
or great scale, for filtering off a clear fluid from a light muddy
sediment. The pressure of the atmosphere may be elegantly applied to
common filters, by the apparatus represented in _fig._ 390., which is
merely a funnel inclosed within a gasometer. The case A B bears an
annular hollow vessel _a b_, filled with water, in which receiver the
cylindrical gasometer _d_, _e_, _f_, _i_, is immersed. The filter funnel
C is secured at its upper edge to the inner surface of the annular
vessel _a b_. In consequence of the pressure of the gasometer regulated
by the weight _g_, upon the air inclosed within it, the liquid is
equally pressed, and the water in the annular space rises to a
corresponding height on the outer surface of the gasometer, as shown in
the figure. Were the apparatus made of sheet iron, the annular space
might be charged with mercury.

In general, relatively to the application of pressure to filters, it may
be remarked, that it cannot be pushed very far, without the chance of
deranging the apparatus, or rendering the filtered liquor muddy. The
enlargement of the surface is, generally speaking, the safest and most
efficacious plan of increasing the rapidity of filtration, especially
for liquids of a glutinous nature. This expedient is well illustrated in
the creased bag filter now in use in most of the sugar refineries of
London. See SUGAR.

In many cases it is convenient so to construct the filtering apparatus,
as that the liquid shall not descend, but mount by hydrostatic pressure.
This method has two advantages: 1. that without much expensive
apparatus, any desired degree of hydrostatic pressure may be given, as
also that the liquid may be forced up through several filtering surfaces
placed alongside of each other; 2. that the object of filtering, which
is to separate the particles floating in the fluid without disturbing
the sediment, may be perfectly attained, and thus very foul liquids be
cleared without greatly soiling the filtering surface.

[Illustration: 391]

Such a construction is peculiarly applicable to the purification of
water, either alone, or combined with the downwards plan of filtration.
Of the former variety an example is shown in _fig._ 391. The wooden or
zinc conical vessel is provided with two perforated bottoms or sieves _e
e_, betwixt which the filtering substance is packed. Over this, for the
formation of the space _h h_, there is a third shelf, with a hole in its
middle, through which the tube _d b_ is passed, so as to be water tight.
This places the upper open part of the apparatus in communication with
the lowest space _a_. From the compartment _h h_ a small air tube _l_
runs upwards. The filtering substance consists at bottom of pebbles, in
the middle of gravel, and at the top of fine sand, which may be mixed
with coarsely ground bone-black, or covered with a layer of the same.
The water to be filtered being poured into the cistern at top, fills
through the tube _b d_ the inferior compartment _a_, from which the
hydrostatic pressure forces the water upward through the perforated
shelf, and the filtering materials. The pure water collects in the space
_h h_, while the air escapes by the small tube _l_, as the liquid
enters. The stopcock _i_ serves to draw off the filtered water. As the
motion of the fluid in the filter is slow, the particles suspended in it
have time to subside by their own gravity; hence there collects over the
upper shelf at _d_, as well as over the under one at _a_, a precipitate
or deposit which may be washed out of the latter cavity by means of the
stopcock _m_.

[Illustration: 392]

As an example of an upwards and downwards filter, _fig._ 392. may be
exhibited. A B C D is a wooden or metallic cistern furnished with the
perforated shelf _c d_ near its under part, upon which a vertical
partition is fixed through the axis of the vessel. A semicircular
perforated shelf is placed at _a_, and a second similar one at _b_.
These horizontal shelves rest upon brackets in the sides of the
cisterns, so that they may be readily lifted out. The space G is filled
with coarse sand, J with moderately fine, and H with very fine. The foul
water is poured into the chamber E, and presses through G J H and into
the space F; whence it may be drawn by the stopcock _f_.

[Illustration: 393]

_Fig._ 393. represents in section a filtering apparatus consisting of
two concentric chambers; the interior being destined for downwards
filtration, and the exterior for upwards. Within the larger cistern A, a
smaller one B is placed concentrically, with its under part, and is left
open from distance to distance, to make a communication between the
interior cavity and the exterior annular space. These cavities are
filled to the marked height with sand and gravel. The inner cylindrical
space has fine sand below, then sharper sand with granular charcoal,
next coarse sand, and lastly gravel. The annular space has in like
manner fine sand below. The foul water is introduced by the pipe E, the
orifice at whose end is acted upon by a ball-cock with its lever _a_;
whereby the water is kept always at the same level in the inner vessel.
The water sinks through the sand strata of the middle vessel, passes
outwards at its bottom into the annular space, thence up through the
sand in it, and collecting above it, is let off by the stopcock on the
pipe _b_. When a muddy deposit forms after some time, it may be easily
cleared out. The cord _e_, running over the pulleys _f f_, being drawn
tight, the ball lever will shut up the valve. The stopcock _d_ made fast
to the conducting tube E must then be opened, so that the water now
overflows into the annular space at A; the tube _c_, in communication
with the inner space B, being opened by taking out the stopper _h_. The
water thereby percolates through the sand strata in the reverse
direction of its usual course, so as to clear away the impurities in the
space B, and to discharge them by the pipe _c h_. An apparatus of this
kind of moderate size is capable of filtering a great body of water. It
should be constructed for that purpose of masonry; but upon a small
scale it may be made of stone-ware.

[Illustration: 394]

A convenient apparatus for filtering oil upwards is represented in
_fig._ 394. _g_ is an oil cask, in which the impure parts of the oil
have accumulated over the bottom. Immediately above this, a pipe _a_ is
let in, which communicates with an elevated water cistern _n_. _f_ is
the filter, (placed on the lid of the cask) furnished with two
perforated shelves, one at _e_ and another at _d_; which divide the
interior of the filter into three compartments. Into the lower space
immediately over the shelf _e_, the tube _b_, furnished with a stopcock
enters, to establish a communication with the cask; the middle cavity
_e_ is filled with coarsely ground charcoal or other filtering
materials; and the upper one has an eduction pipe _l_. When the
stopcocks of the tubes _a_ and _b_ are opened, the water passes from the
cistern into the oil cask, occupies from its density always the lowest
place, and presses the oil upwards, without mixing the two liquids;
whereby first the upper and purer portion of the oil is forced through
tube _b_ into the filter, and thence out through the pipe _l_. When the
fouler oil follows, it deposits its impurities in the space under the
partition _c_, which may from time to time be drawn off through the
stopcock _k_, while the purer oil is pressed upwards through the filter.
In this way the different strata of oil in the cask may be filtered off
in succession, and kept separate, if found necessary for sale or use,
without running any risk of mixing up the muddy matter with what is
clear. According to the height of the water cistern _n_, will be the
pressure, and of course the filtering force. When the filter gets choked
with dirt, it may be easily re-charged with fresh materials.

In filtering caustic alkaline lyes through linen or quartz, it is proper
to exclude the free contact of air; which is done by inclosing the upper
vessel, and attaching a pipe of communication between its cover, and the
shoulder of the lower vessel, or recipient of the lyes. In proportion as
these flow down, they will displace their bulk of air, and drive it into
the top of the upper vessel above the foul lyes.

Many modifications of the above described apparatus are now on sale in
this country; but certainly the neatest, most economical, and effective
means of transforming the water of a stagnant muddy pool, into that of a
crystalline fountain, is afforded by the Royal Patent Filters of George
Robins.


FIRE ARMS, MANUFACTURE OF. This art is divided into two branches, that
of the metallic and of the wooden work. The first includes the barrel,
the lock, and the mounting, as also the bayonet and ramrod, with
military arms. The second comprises the stock, and in fowling pieces,
likewise the ramrod.

1. _The Barrel._ Its interior is called the bore; its diameter, the
calibre; the back end, the breech; the front end, the muzzle; and the
closing of the back end, the breech pin or plug. The barrel is generally
made of iron. Most military musquets and low-priced guns are fashioned
out of a long slip of sheet-iron folded together edge-wise round a
skewer into a cylinder, are then lapped over at the seam, and welded at
a white heat. The most ductile and tenacious soft iron, free from all
blemishes, must be selected for this slip. It is frequently welded at
the common forge, but a proper air-furnace answers better, not being so
apt to burn it. It should be covered with ashes or cinders. The shape of
the bore is given by hammering the cylinder upon a steel mandril, in a
groove of the anvil. Six inches of the barrel at either end are left
open for forming the breech and the muzzle by a subsequent welding
operation; the extremity put into the fire being stopped with clay, to
prevent the introduction of cinders. For every length of two inches,
there are from two to three welding operations, divided into alternating
high and low heats; the latter being intended to correct the defects of
the former. The breech and muzzle are not welded upon the mandril, but
upon the horn of the anvil; the breech being thicker in the metal, is
more highly heated, and is made somewhat wider to save labour to the
borer. The barrel is finally hammered in the groove of the anvil without
the mandril, during which process it receives a heat every two minutes.
In welding, the barrel extends about one-third in length; and for
musquets, is eventually left from 3 to 3-1/2 feet long; but for cavalry
pistols, only 9 inches.

The best iron plates for gun-barrels are those made of _stub_ iron, that
is of old horse-shoe nails welded together, and forged into thin bars,
or rather narrow ribands. At one time _damascus_ barrels were much in
vogue; they were fashioned either as above described, from plates made
of bars of iron and steel laid parallel, and welded together, or from
ribands of the same damascus stuff coiled into a cylinder at a red heat,
and then welded together at the seams. The best modern barrels for
fowling pieces are constructed of stub-nail iron in this manner. The
slip or fillet is only half an inch broad or sometimes less, and is left
thicker at the end which is to form the breech, and thinner at the end
which is to form the muzzle, than in the intermediate portion. This
fillet being moderately heated to increase its pliancy, is then lapped
round the mandril in a spiral direction till a proper length of cylinder
is formed; the edges being made to overlap a little in order to give
them a better hold in the welding process. The coil being taken off the
mandril and again heated, is struck down vertically with its muzzle end
upon the anvil, whereby the spiral junctions are made closer and more
uniform. It is now welded at several successive heats, hammered by
horizontal strokes, called _jumping_, and brought into proper shape on
the mandril. The finer barrels are made of still narrower, stub-iron
slips, whence they get the name of wire twist. On the Continent, barrels
are made of steel wire, welded together lengthwise, then coiled spirally
into a cylinder. Barrels that are to be rifled, require to be made of
thicker iron, and that of the very best quality, for they would be
spoiled by the least portion of scale upon their inside. Soldiers’
musquets are thickened a little at the muzzle, to give a stout holding
to the bayonet.

[Illustration: 395]

The barrels thus made are annealed with a gentle heat in a proper
furnace, and slowly cooled. They are now ready for the borer, which is
an oblong square _bit_ of steel, pressed in its rotation against the
barrel, by a slip of wood applied to one of its flat sides, and held in
its place by a ring of metal. The boring bench works horizontally, and
has a very shaky appearance, in respect at least of the bit. In some
cases, however, it has been attempted to work the barrels and bits at an
inclination to the horizon of 30°, in order to facilitate the discharge
of the borings. The barrel is held in a slot by only one point, to allow
it to humour the movements of the borer, which would otherwise be
infallibly broken. The bit, as represented in _fig._ 395., has merely
its square head inserted into a clamp-chuck of the lathe, and plays
freely through the rest of its length.

[Illustration: 396]

_Fig._ 396. represents in plan the _boring bench_ for musquet barrels;
_f f_ is the sledge or carriage frame in which the barrel is supported;
_a_ is the revolving chuck of the lathe, into which the square end of
the bit, _fig._. 395., is inserted; _b_ is the barrel, clamped at its
middle to the carriage, and capable of being pressed onwards against the
tapering bit of the borer, by the bent lever _c_, worked by the left
hand of the operative against fulcrum knobs at _d_, which stand about
two inches asunder. Whenever the barrel has been thereby advanced a
certain space to the right, the bent end of the lever is shifted against
another knob or pin. The borer appears to a stranger to be a very
awkward and unsteady mechanism, but its perpetual vibrations do not
affect the accuracy of the bore. The opening broach may be of a square
or pentagonal form; and either gradually tapered from its thickest part,
or of uniform diameter till within two inches of the end, whence it is
suddenly tapered to a point.

A series of bits may be used for boring a barrel, beginning with the
smallest and ending with the largest. But this multiplication of tools
becomes unnecessary, by laying against the cutting part of the bit,
slips of wood, called spales, of gradually increasing thickness, so that
the edge is pressed by them progressively further from the axis. The
bore is next polished. This is done by a bit with a very smooth edge,
which is mounted as above, with a wedge of wood besmeared with a mixture
of oil and emery. The inside is finished by working a cylindrical steel
file quickly backwards and forwards within it, while it is revolving
slowly.

In boring, the bit must be well oiled or greased, and the barrel must be
kept cool by letting water trickle on it; for the bit, revolving at the
rate of 120 or 140 times a minute, generates a great deal of heat. If a
flaw be detected in the barrel during the boring, that part is hammered
in, and then the bit is employed to turn it out.

Many sportsmen are of opinion that a barrel with a bore somewhat
narrowed towards the muzzle serves to keep shot better together; and
that roughening its inside with pounded glass has a good effect, with
the same view. For this purpose, also, fine spiral lines have been made
in their interior surface. The justness of its calibre is tried by means
of a truly turned cylinder of steel, 3 or 4 inches long, which ought to
move without friction, but with uniform contact from end to end of the
barrel. Whatever irregularities appear must be immediately removed.

The outer surface of the barrel is commonly polished upon a dry
grindstone, but it is better finished, and less dangerously to the
workman, at a turning lathe with a slide rest. If a stone be used, it
should be made to revolve at the mouth of a tunnel of some kind, into
which there is a good draught to carry off the ferruginous particles. A
piece of moist cloth or leather should be suspended before the orifice.

Rifle barrels have parallel grooves of a square or angular form cut
within them, each groove being drawn in succession. These grooves run
spirally, and form each an aliquot part of a revolution from the chamber
to the muzzle. Rifles should not be too deeply indented; only so much as
to prevent the ball turning round within the barrel. and the spires
should be truly parallel, that the ball may glide along with a regular
pace. See _infra_.

The Parisian gun-makers, who are reckoned very expert, draw out the iron
for the barrels at hand forges, in fillets only one-ninth of an inch
thick, one inch and a half broad, and four feet long. Twenty-five of
these ribands are laid upon each other, between two similar ones of
double thickness, and the bundle, weighing 60 pounds, bound with wire at
two places, serves to make two barrels. The thicker plates are intended
to protect the thinner from the violence of the fire in the numerous
successive heats necessary to complete the welding, and to form the
bundle into a bar two-thirds of an inch broad, by half an inch thick;
the direction of the individual plates relatively to the breadth being
preserved. This bar folded flat upon itself, is again wrought at the
forge, till it is only half an inch broad, and a quarter of an inch
thick, while the plates of the primitive ribands are now set
perpendicular to the breadth of the narrow fillet; the length of which
must be 15 or 16 feet French (16 or 17 English), to form a fowling piece
from 28 to 30 inches long. This fillet, heated to a cherry red in
successive portions, is coiled into as close a spiral as possible, upon
a mandril about two-fifths of an inch in diameter. The mandril has at
one end a stout head for drawing it out, by means of the hammer and the
grooves of the anvil, previous to every heating. The welding is
performed upon a mandril introduced after each heat; the middle of the
barrel being first worked, while the fillets are forced back against
each other, along the surface of the mandril, to secure their perfect
union. The original plates having in the formation of the ultimate long
riband become very thin, appear upon the surface of the barrel like
threads of a fine screw, with blackish tints to mark the junctions. In
making a double-barrelled gun, the two are formed from the same bundle
of slips, the coils of the one finished fillet being turned to the right
hand, and those of the other to the left.

The Damascus barrels forged as above described, from a bundle of steel
and iron plates laid alternately together, are twisted at the forge
several times, then coiled and welded as usual. Fifteen Parisian workmen
concur in one operation: six at the forge; two at the boring mill; seven
at filing, turning, and adjusting; yet all together make only six pairs
of barrels per week, which are sold at from 100 to 300 francs the pair,
ready for putting into the stock.

[Illustration: 397 398]

The breeching is of three kinds: the common; the chamber, plug, or
mortar, _fig._ 397.; and the patent, _fig._ 398. The common was formerly
used for soldiers’ musquets and inferior pieces. The second is a
trifling improvement upon it. In the patent breeching, the screws do not
interfere with the touch-hole, and the ignition is quicker in the main
chamber.

[Illustration: 399]

The only locks which it is worth while to describe are those upon the
percussion principle, as flint locks will certainly soon cease to be
employed even in military musquets. Forsyth’s lock (_fig._ 399.) was an
ingenious contrivance. It has a magazine _a_, for containing the
detonating powder, which revolves round a roller _b_, whose end is
screwed into the breech of the barrel. The priming powder passes through
a small hole in the roller, which leads to a channel in communication
with the chamber of the gun.

The pan for holding the priming is placed immediately over the little
hole in the roller. There is a steel punch _c_, in the magazine, whose
under end stands above the pan, ready to ignite the priming when struck
upon the top by the cock _d_, whenever the trigger is drawn. The punch
immediately after being driven down into the pan is raised by the action
of a spiral spring. For each explosion, the magazine must be turned so
far round as to let fall a portion of the percussion powder into the
pan; after which it is turned back, and the steel punch recovers its
proper position for striking another blow into the pan.

[Illustration: 400]

The invention of the copper percussion cap was another great improvement
upon the detonating plan. _Fig._ 400. represents the ordinary percussion
lock, which is happily divested of three awkward projections upon the
flint lock, namely, the hammer, hammer spring, and the pan. Nothing now
appears upon the plate of the lock, but the cock or striking hammer,
which inflicts the proper blow upon the percussion cap. It is concave,
with a small metallic ring or border, called a shield or fence, for the
purpose of enclosing the cap, as it were, and preventing its splinters
doing injury to the sportsman, as also protecting against the line of
flame which may issue from the touch-hole in the cap nipple. This is
screwed into the patent breech, and is perforated with a small hole.

[Illustration: 401]

The safety lock of Dr. Somerville is a truly humane invention. Its
essential feature is a slide stop or catch, placed under the trigger A,
_fig._ 401. It is pulled forward into a notch in the trigger, by means
of a spring B, upon the front of the guard, which is worked by a key C,
pressing upon the spring when the piece is discharged. In another safety
plan there is a small movable curved piece of iron, A, which rises
through an opening B, in the lock-plate C, and prevents the cock from
reaching the nipple, as represented in the figure, until it is drawn
back within the plate of the lock when the piece is fired.

To fire this gun, two different points must be pressed at the same time.
If by accident the key which works the safety be touched, nothing
happens, because the trigger is not drawn; and the trigger touched alone
can produce no effect, because it is locked. The pressure must be
applied to the trigger and the key at the same instant, otherwise the
lock will not work.

The French musquet is longer than the British, in the proportion of
44·72 inches to 42; but the French bayonet is 15 inches, whereas the
British is 17.

                                                Eng.             Fr.
                                             Dimensions.     Dimensions.
  Diameter of the bore                         0·75 in.         0·69 in.
  Diameter of the ball                         0·676            0·65
  Weight of the ball in oz.                    1·06             0·958
  Weight of the firelock and bayonet in libs. 12·25            10·980
  Length of the barrel and bayonet            59·00            59·72

[Illustration: 402]

Within these few years a great many contrivances have been brought
forward, and several have been patented for fire arms. The first I shall
notice is that of Charles Random, Baron de Berenger. _Fig._ 402. shows
the lock and breech of a fowling piece, with a sliding protector on one
of the improved plans; _a_ is the hammer, _b_ the nipple of the
touch-hole, _c_ a bent lever, turning upon a pin, fixed into the
lock-plate at _d_. The upper end of this bent lever stands partly under
the nose of the hammer, and while in that situation stops it from
striking the nipple. A slider _g f h_, connected with the under part of
the gun-stock, is attached to the tail of the bent lever at _i_; and
when the piece is brought to the shoulder for firing, the hand of the
sportsman pressing against the bent part of the slider at _g_, forces
this back, and thereby moves the end of the lever _c_ forwards from
under the nose of the cock or hammer, as shown by the dotted lines. The
trigger being now drawn, the piece will be discharged; and on removing
the hand from the end _g_, of the slider _f_, the spring at _h_ acting
against the guard, will force the slider forward, and the lever into the
position first described.

[Illustration: 403]

Mr. Redford, gun-maker of Birmingham, proposes a modification of the
lock for small fire-arms, in which the application of pressure to the
sear spring for discharging the piece is made by means of a plug,
depressed by the thumb, instead of the force of the finger exerted
against the trigger. _Fig._ 403. represents a fowling piece partly in
section. The sear spring is shown at _a_. It is not here connected with
the trigger as in other locks; but is attached by a double-jointed piece
to a lever _b_, which turns upon a fulcrum pin in its centre. At the
reverse end of this lever an arm extends forwards, like that of an
ordinary sear spring, upon which arm the lower end of the plug _c_ is
intended to bear; and when this plug is depressed by the thumb bearing
upon it, that end of the lever _b_ will be forced downwards, and the
reverse end will be raised, so as to draw up the end of the sear spring,
and set off the piece. For the sake of protection, the head of the plug
_c_ is covered by a movable cap _d_, forming part of a slider _e_, which
moves to and fro in a groove in the stock, behind the breech end of the
barrel; this slider _e_ is acted upon by the trigger through levers,
which might be attached to the other side of the lock-plate; but are not
shown in this figure to avoid confusion. When the piece is brought to
the shoulder for firing, the fore-finger must be applied as usual to the
trigger, but merely for the purpose of drawing back the slider _e_, and
uncovering the head of the plug; when this is done, the thumb is to be
pressed upon the head of the plug, and will thus discharge the piece. A
spring bearing against the lever of the slider _e_, will, when the
finger is withdrawn from the trigger, send the slider forward again, and
cover the head of the plug, as shown.

It is with pleasure I again advert to the humane ingenuity of the Rev.
John Somerville, of Currie. In April, 1835, he obtained a patent for a
further invention to prevent the accidental discharge of fire arms. It
consists in hindering the hammer from reaching the nipple of a
percussion lock, or the flint reaching the steel of an ordinary one, by
the interposition of movable safety studs or pins, which protrude from
under the false breech before the hammers of the locks, and prevent them
from descending to strike. These safety studs or pins are moved out of
the way by the pressure of the right hand of the person using the gun
only when in the act of firing, that is, when the force of the right
hand and arm is exerted to press the butt end of the stock of the gun
against the shoulder while the aim is taken and the trigger pulled. In
carrying the gun at rest, the proper parts of the thumb or hand do not
come over Mr. Somerville’s movable buttons or studs.

[Illustration: 404 405]

_Fig._ 404. is a side view of part of a double percussion gun; and
_fig._ 405. is a top or plan view, which will serve to explain these
improvements, and show one, out of many, methods of carrying them into
effect. A is the stock of the gun; B the barrels; C the breech; D the
nipples; E the false breech, on the under side of which the levers which
work the safety studs or pins are placed; F is the shield of the false
breech; G, triggers; H the lock-plate; and I the hammers: all of which
are constructed as usual: _a a_ are the safety studs or pins, which
protrude before the shield F, and work through guide pieces on the under
side of the false breech. The button piece is placed in the position for
the thumb of the right hand to act upon it; but when the pressure of the
ball of the right thumb is to produce the movement of the safety studs,
it must be placed in or near the position K; and when the heel of the
right hand is to effect the movements of the safety studs, the button
piece must be placed at L, or nearly so.

In these last two positions, the lever (which is acted upon by the
button piece to work the safety studs through a slide) would require to
be of a different shape and differently mounted. When the hammers are
down upon the nipples after discharging the gun, the ends of the safety
pins press against the inner sides of the hammers. When this invention
is adapted to single-barrelled guns, only one pin, _a_, one lever and
button piece will be required.

[Illustration: 406]

Mr. Richards, gun-maker, Birmingham, patented, in March, 1836, a
modification of the copper cap for holding the percussion powder, as
represented _fig._ 406.; in which the powder is removed from the top of
the cap, and brought nearer the mouth; _a_ being the top, _b_ the sides,
and _c_ the position of the priming. The dotted lines show the direction
of the explosion, whereby it is seen that the metal case is opened or
distended only in a small degree, and not likely to burst to pieces, as
in the common caps, the space between _a_ and _c_ being occupied by a
piece of any kind of hard metal _d_, soldered or otherwise fastened in
the cap.

George Lovell, Esq., director of the Royal Manufactory of Arms at
Enfield, has recently made a great improvement upon the priming chamber.
He forms it into a vertical double cone, joined in the middle by the
common apex; the base of the upper cone being in contact with the
percussion cap, presents the most extensive surface to the fulminate
upon the one hand, while the base of the under one being in a line with
the interior surface of the barrel, presents the largest surface to the
gunpowder charge, upon the other. In the old nipple the apex of the cone
being at its top, afforded very injudiciously the _minimum_ surface to
the exploding force.

_Guns, Rifling of the Barrels._--The outside of rifle barrels is, in
general, octagonal. After the barrel is bored, and rendered truly
cylindrical, it is fixed upon the rifling machine. This instrument is
formed upon a square plank of wood 7 feet long, to which is fitted a
tube about an inch in diameter, with spiral grooves deeply cut
internally through its whole length; and to this a circular plate is
attached, about 5 inches diameter, accurately divided in concentric
circles, into from 5 to 16 equal parts, and supported by two rings made
fast to the plank, in which rings it revolves. An arm connected with the
dividing graduated plate, and pierced with holes, through which a pin
is passed, regulates the change of the tube in giving the desired number
of grooves to the barrel. An iron rod, with a movable handle at the one
end, and a steel cutter in the other, passes through the above rifling
tube. This rod is covered with a core of lead one foot long. The barrel
is firmly fixed by two rings on the plank, standing in a straight line
on the tube. The rod is now drawn repeatedly through the barrel, from
end to end, until the cutter has formed one groove of the proper depth.
The pin is then shifted to another hole in the dividing plate, and the
operation of grooving is repeated till the whole number of riflings is
completed. The barrel is next taken out of the machine, and finished.
This is done by casting upon the end of a small iron rod a core of lead,
which, when besmeared with a mixture of fine emery and oil, is drawn,
for a considerable time, by the workmen, from the one end of the barrel
to the other, till the inner surface has become finely polished. The
best degree of spirality is found to be from a quarter to half a
revolution in a length of three feet.

_Military Rifles._--An essential improvement in this destructive arm has
lately been introduced into the British service, at the suggestion of
Mr. Lovell:

[Illustration: 407 408 409 410]

The intention in all rifles is to impart to the ball a rotatory or
spinning motion round its axis, as it passes out through the barrel.
This object was attained, to a certain degree, in the rifles of the old
pattern, by cutting seven spiral grooves into the inside of the barrel,
in the manner shewn by _fig._ 407., the spherical ball, _fig._ 408.,
being a little larger than the bore, was driven down with a mallet, by
which the projecting ribs were forced into the surface of the ball, so
as to keep it in contact with their curvatures, during its expulsion.
Instead of this laborious and insecure process, the barrel being now cut
with only two opposite grooves, _fig._ 409., and the ball being formed
with a projecting belt, or zone, round its equator, of the same form as
the two grooves, _fig._ 410., it enters so readily into these hollows,
that little or no force is required to press it down upon the powder. So
much more hold of the barrel is at the same time obtained, that instead
of one _quarter_ of a turn, which was the utmost that could be safely
given in the old way, without danger of stripping the ball, a _whole_
turn round the barrel, in its length, can be given to the two grooved
rifles; whereby a far more certain and complete rotatory motion is
imparted to the ball. The grand practical result is, that better
practice has been performed by several companies of the Rifle Corps, at
300 yards, than could be produced with the best old military rifles at
150 yards; the soldier being meanwhile enabled to load with much greater
ease and despatch. The belt is bevelled to its middle line, and not so
flat as shown in the figure.

This mode of rifling is not, however, new in England. In fact, it is one
of the oldest upon record; and appears to have fallen into disuse from
faults in the execution. The idea was revived within the last few years
in Brunswick, and it was tried in Hanover also, but with a lens-shaped
(Linsenförmig) ball. The judicious modifications and improvements it has
finally received in Mr. Lovell’s hands, have brought out all its
advantages, and rendered it, when skilfully used, a weapon of unerring
aim, even at the prodigious distance of 700 yards.

[Illustration: 411

_Mr. Lovell’s Lock._]

The locks, also, for the military service generally, are now receiving
an important improvement by means of his labours, having been simplified
in a remarkable manner. The action of the main spring is reversed, as
shown by _fig._ 411.; thus rendering the whole mechanism more solid,
compact, and convenient; while the ignition of the charge being effected
by percussion powders in a copper cap, the fire of the British line
will, in future, be more murderous than ever, as a mis-fire is hardly
ever experienced with the fire-arms made at the Royal manufactory, under
Mr. Lovell’s skilful superintendence.


FIRE-DAMP; the explosive carburetted hydrogen of coal mines. See
PITCOAL.


FIRE-WORKS. (_Feux d’artifice_, Fr.; _Feuerwerke_, Germ.) The
composition of luminous devices with explosive combustibles, is a modern
art resulting from the discovery of gunpowder. The finest inventions of
this kind are due to the celebrated Ruggieri, father and son, who
executed in Rome and Paris, and the principal capitals of Europe, the
most brilliant and beautiful fireworks that were ever seen. The
following description of their processes will probably prove interesting
to many of my readers.

The three prime materials of this art are, nitre, sulphur, and charcoal,
along with filings of iron, steel, copper, zinc, and resin, camphor,
lycopodium, &c. Gunpowder is used either in grain, half crushed, or
finely ground, for different purposes. The longer the iron filings, the
brighter red and white sparks they give; those being preferred which are
made with a very coarse file, and quite free from rust. Steel filings
and cast-iron borings contain carbon, and afford a more brilliant fire,
with wavy radiations. Copper filings give a greenish tint to flame;
those of zinc, a fine blue colour; the sulphuret of antimony gives a
less greenish blue than zinc, but with much smoke; amber affords a
yellow fire, as well as colophony, and common salt; but the last must be
very dry. Lampblack produces a very red colour with gunpowder, and a
pink with nitre in excess. It serves for making golden showers. The
yellow sand or glistening mica, communicates to fire-works golden
radiations. Verdigris imparts a pale green; sulphate of copper and
sal-ammoniac, a palm-tree green. Camphor yields a very white flame and
aromatic fumes, which mask the bad smell of other substances. Benzoin
and storax are used also on account of their agreeable odour. Lycopodium
burns with a rose colour and a magnificent flame; but it is principally
employed in theatres to represent lightning, or to charge the torch of a
fury.

Fire-works are divided into three classes: 1. those to be set off upon
the ground; 2. those which are shot up into the air; and 3. those which
act upon or under water.

Composition for _jets of fire_; the common preparation for rockets not
more than 3/4 of an inch in diameter, is: gunpowder, 16 parts; charcoal,
3 parts. For those of larger diameter: gunpowder, 16; steel filings, 4.

_Brilliant revolving wheel_; for a tube less than 3/4 of an inch:
gunpowder, 16; steel filings, 3. When more than 3/4: gunpowder, 16;
filings, 4.

_Chinese or Jasmine fire_; when less than 3/4 of an inch: gunpowder, 16;
nitre, 8; charcoal (fine), 3; sulphur, 3; pounded cast-iron borings
(small), 10. When wider than 3/4: gunpowder, 16; nitre, 12; charcoal, 3;
sulphur, 3; coarse borings, 12.

_A fixed brilliant_; less than 3/4 in diameter: gunpowder, 16; steel
filings, 4; or, gunpowder, 16; and finely pounded borings, 6.

_Fixed suns_ are composed of a certain number of jets of fire
distributed circularly, like the spokes of a wheel. All the fusees take
fire at once through channels charged with quick matches. _Glories_ are
large suns with several rows of fusees. _Fans_ are portions of a sun,
being sectors of a circle. The _Patte d’oie_ is a fan with only three
jets.

The _mosaic_ represents a surface covered with diamond shaped
compartments, formed by two series of parallel lines crossing each
other. This effect is produced by placing at each point of intersection,
four jets of fire, which run into the adjoining ones. The intervals
between the jets must be associated with the discharge of others, so as
to keep up a succession of fires in the spaces.

_Palm trees._ Ruggieri contrived a new kind of fire, adapted to
represent all sorts of trees, and especially the palm. The following is
the composition of this magnificent green fire-work: crystallized
verdigris, 4 parts; sulphate of copper, 2; sal-ammoniac, 1. These
ingredients are to be ground and moistened with alcohol. An artificial
tree of any kind being erected, coarse cotton rovings about 2 inches in
diameter, impregnated with that composition, are to be festooned round
the trunk, branches, and among the leaves; and immediately kindled
before the spirits have had time to evaporate.

_Cascades_, imitate sheets or jets of water. The Chinese fire is best
adapted to such decorations.

_Fixed stars._ The bottom of a rocket is to be stuffed with clay, and
one diameter in height of the first preparation being introduced, the
vacant space is to be filled with the following composition, and the
mouth tied up. The pasteboard must be pierced into the preparation, with
five holes, for the escape of the luminous rays, which represent a
star.

_Composition of fixed stars_:--

                 Ordinary.  Brighter.  Coloured.
  Nitre,            16         12         0
  Sulphur,           4          6         6
  Gunpowder meal,    4         12        16
  Antimony,          2          1         2

_Lances_, are long rockets of small diameter, made with cartridge paper.
Those which burn quickest should be the longest. They are charged by
hand without any mould, with rods of different lengths, and are not
strangled at the mouth, but merely stuffed with a quick match of tow.
These lances form the figures of great decorations; they are fixed with
sprigs upon large wooden frame works, representing temples, palaces,
pagodas, &c. The whole are placed in communication by _conduits_, or
small paper cartridges like the lances, but somewhat conical, that they
may fit endwise into one another to any extent that may be desired. Each
is furnished with a match thread fully 1-1/2 inches long, at its two
ends.

Composition for the _white lances_: nitre, 16; sulphur, 8; gunpowder, 4
or 3. For a _bluish-white_: nitre, 16; sulphur, 8; antimony, 4. For
_blue lances_: nitre, 16; antimony, 8. For _yellow_: nitre, 16;
gunpowder, 16; sulphur, 8; amber, 8. For _yellower_ ones: nitre, 16;
gunpowder, 16; sulphur, 4; colophony, 3; amber, 4. For _greenish_ ones:
nitre, 16; sulphur, 6; antimony, 6; verdigris, 6. For _pink lances_;
nitre, 16; gunpowder, 3; lampblack, 1. Others less vivid are made with:
nitre, 16; colophony, 3; amber, 3; lycopodium, 3.

Cordage is represented in fire-works, by imbuing soft ropes with a
mixture of, nitre, 2; sulphur, 16; antimony, 1; resin of juniper, 1.

The Bengal flames rival the light of day. They consist of, nitre, 7;
sulphur, 2; antimony, 1. This mixture is pressed strongly into earthen
porringers, with some bits of quick match strewed over the surface.
These flames have a fine theatrical effect for conflagrations.

_Revolving suns_, are wheels upon whose circumference rockets of
different styles are fixed, and which communicate by _conduits_, so that
one is lighted up in succession after another. The composition of their
common fire is, for sizes below 3/4 of an inch: gunpowder meal, 16;
charcoal, not too fine, 3. For larger sizes: gunpowder, 20; charcoal,
not too fine, 4. For _fiery radiations_: gunpowder, 16; yellow micaceous
sand, 2 or 3. For _mixed radiations_: gunpowder, 16; pitcoal, 1; yellow
sand, 1 or 2.

The _waving or double Catherine wheels_, are two suns turning about the
same axis in opposite directions. The fusees are fixed obliquely and not
tangentially to their peripheries. The wheel spokes are charged with a
great number of fusees; two of the four wings revolve in the one
direction, and the other two in the opposite; but always in a vertical
plane.

The _girandoles_, _caprices_, _spirals_, and some others have on the
contrary a horizontal rotation. The fire-worker may diversify their
effects greatly by the arrangement and colour of the jets of flame. Let
us take for an example the _globe of light_. Imagine a large sphere
turning freely upon its axis, along with a hollow hemisphere, which
revolves also upon a vertical axis passing through its under pole. If
the two pieces be covered with coloured lances or cordage, a fixed
luminous globe will be formed, but if horizontal fusees be added upon
the hemisphere, and vertical fusees upon the sphere, the first will have
a relative horizontal movement, the second a vertical movement, which
being combined with the first, will cause it to describe a species of
curve, whose effect will be an agreeable contrast with the regular
movement of the hemisphere. Upon the surface of a revolving sun, smaller
suns might be placed, to revolve like satellites round their primaries.

Ruggieri exhibited a luminous serpent pursuing with a rapid winding
pace, a butterfly which flew continually before it. This extraordinary
effect was produced in the following way. Upon the summits of an octagon
he fixed eight equal wheels turning freely upon their axles, in the
vertical plane of the octagon. An endless chain passed round their
circumference, going from the interior to the exterior, covering the
outside semi-circumference of the first, the inside of the second, and
so in succession; whence arose the appearance of a great festooned
circular line. The chain, like that of a watch, carried upon a portion
of its length a sort of scales pierced with holes for receiving coloured
lances, in order to represent a fiery serpent. At a little distance
there was a butterfly constructed with white lances. The piece was
kindled commonly by other fireworks, which seemed to end their play, by
projecting the serpent from the bosom of the flames. The motion was
communicated to the chain by one of the wheels, which received it like a
clock from the action of a weight. This remarkably curious mechanism was
called by the artists a _salamander_.

_The rockets which rise into the air_ with a prodigious velocity, are
among the most common, but not least interesting fire-works. When
employed profusely they form those rich volleys of fire which are the
crowning ornaments of a public fête. The cartridge is similar to that of
the other jets, except in regard to its length, and the necessity of
pasting it strongly, and planing it well; but it is charged in a
different manner. As the sky-rockets must fly off with rapidity, their
composition should be such as to kindle instantly throughout their
length, and extricate a vast volume of elastic fluids. To effect this
purpose, a small cylindric space is left vacant round the axis; that is,
the central line is tubular. The fire-workers call this space the soul
of the rocket (_ame de la fusée_). On account of its somewhat conical
form, hollow rods, adjustable to different sizes of broaches or skewers,
are required in packing the charge; which must be done while the
cartridge is sustained by its outside mould, or copper cylinder. The
composition of sky-rockets is as follows:--

  +-------------------------+----------+---------+------+
  |   When the bore is      |3/4 of an | 3/4 to  |1-2/3;|
  |                         |  inch;   | 1-1/4;  |      |
  +-------------------------+----------+---------+------+
  |Nitre                    |16        |16       | 16   |
  |Charcoal                 | 7        | 8       |  9   |
  |Sulphur                  | 4        | 4       |  4   |
  | _Brilliant Fire._       |          |         |      |
  |Nitre                    |16        |16       | 16   |
  |Charcoal                 | 6        | 7       |  8   |
  |Sulphur                  | 4        | 4       |  4   |
  |Fine steel filings       | 3        | 4       |  5   |
  |  _Chinese Fire._        |          |         |      |
  |Nitre                    |16        |16       | 16   |
  |Charcoal                 | 4        | 5       |  6   |
  |Sulphur                  | 3        | 3       |  4   |
  |Fine borings of cast iron| 3 coarser| 4 mixed |  5   |
  +-------------------------+----------+---------+------+

The cartridge being charged as above described, the _pot_ must be
adjusted to it, with the _garniture_; that is, the serpents, the
crackers, the stars, the showers of fire, &c. The pot is a tube of
pasteboard wider than the body of the rocket, and about one third of its
length. After being strangled at the bottom like the mouth of a phial,
it is attached to the end of the fusee by means of twine and paste.
These are afterwards covered with paper. The garniture is introduced by
the neck, and a paper plug is laid over it. The whole is inclosed within
a tube of pasteboard terminating in a cone, which is firmly pasted to
the pot. The quick-match is now finally inserted into the _soul_ of the
rocket. The rod attached to the end of the sky-rockets to direct their
flight, is made of willow or any other light wood. M. Ruggieri replaced
the rod by conical wings containing explosive materials, and thereby
made them fly further and straighter.

The _garnitures_ of the sky-rocket pots are the following:--

1. _Stars_ are small, round, or cubic solids, made with one of the
following compositions, and soaked in spirits. _White stars_, nitre, 16;
sulphur, 8; gunpowder, 3. Others more vivid consist of nitre, 16;
sulphur, 7; gunpowder, 4.

_Stars for golden showers_, nitre, 16; sulphur, 10; charcoal, 4;
gunpowder, 16; lamp-black, 2. Others yellower are made with nitre, 16;
sulphur, 8; charcoal, 2; lamp-black, 2; gunpowder, 8.

The _serpents_ are small fusees made with one or two playing cards;
their bore being less than half an inch. The _lardons_ are a little
larger, and have three cards; the _vetilles_ are smaller. Their
composition is, nitre, 16; charcoal, not too fine, 2; gunpowder, 4;
sulphur, 4; fine steel filings, 6.

The _petards_ are cartridges filled with gunpowder and strangled.

The _saxons_ are cartridges clayed at each end, charged with the
brilliant turning fire, and perforated with one or two holes at the
extremity of the same diameter.

The _cracker_ is a round or square box of pasteboard, filled with
granulated gunpowder, and hooped all round with twine.

_Roman candles_ are fusees which throw out very bright stars in
succession. With the composition (as under) imbued with spirits and
gum-water, small cylindric masses are made, pierced with a hole in their
centre. These bodies, when kindled and projected into the air, form the
stars. There is first put into the cartridge a charge of fine gunpowder
of the size of the star; above this charge a star is placed; then a
charge of composition for the Roman candles.

The _stars_, when less than 3/4 of an inch, consist of nitre, 16;
sulphur, 7; gunpowder, 5. When larger, of nitre, 16; sulphur, 8;
gunpowder, 8.

_Roman candles_, nitre, 16; charcoal, 6; sulphur, 3. When above 3/4 of
an inch nitre, 16; charcoal, 8; sulphur, 6.

The _girandes_, or bouquets, are those beautiful pieces which usually
conclude a fire-work exhibition; when a multitude of jets seem to
emblazon the sky in every direction, and then fall in golden showers.
This effect is produced by distributing a number of cases open at top,
each containing 140 sky-rockets, communicating with one another by
quick-match strings planted among them. The several cases communicate
with each other by _conduits_, whereby they take fire simultaneously,
and produce a volcanic display.

_The water fire-works_ are prepared like the rest; but they must be
floated either by wooden bowls, or by discs and hollow cartridges fitted
to them.

_Blue fire for lances_ may be made with nitre, 16; antimony, 8; very
fine zinc filings, 4. Chinese paste for the stars of Roman candles,
bombs, &c.:--Sulphur, 16; nitre, 4; gunpowder meal, 12; camphor, 1;
linseed oil, 1; the mixture being moistened with spirits.

The _feu grégois_ of Ruggieri, the son:--Nitre, 4; sulphur, 2; naphtha,
1. See PYROTECHNY and ROCKETS.

The red fire composition is made by mixing 40 parts of nitrate of
strontia, 13 of flowers of sulphur, 5 of chlorate of potash, and 4 of
sulphuret of antimony.

White fire is produced by igniting a mixture of 48 parts nitre; 13-1/4
sulphur; 7-1/4 sulphuret of antimony; or, 24 nitre, 7 sulphur, 2
realgar; or, 75 nitre, 24 sulphur, 1 charcoal; or, finally, 100 of
gunpowder meal, and 25 of cast-iron fine borings.

The blue fire composition is, 4 parts of gunpowder meal; 2 of nitre;
sulphur and zinc, each 3 parts.


FISH-HOOKS (_Hameçons_, Fr.; _Fischangeln_, Germ.); are constructed with
simple tools, but require great manual dexterity in the workmen. The
iron wire of which they are made should be of the best quality, smooth,
and sound. A bundle of such wire is cut in lengths, either by shears or
by laying it down upon an angular wedge of hard steel fixed horizontally
in a block or anvil, and striking off the proper lengths by the blows of
a hammer. In fashioning the _barbs_ of the hooks, the straight piece of
wire is laid down in the groove of an iron block made on purpose, and is
dexterously struck by the chisel in a slanting direction, across so much
of the wire as may be deemed necessary. A sharp-pointed little wedge is
thus formed, whose base graduates into the substance of the metal.

The end of the wire where the line is to be attached is now flattened or
screw-tapped; the other end is sharp pointed, and the proper twisted
curvature is given. The soft iron hooks are next case-hardened, to give
them the steely stiffness and elasticity, by imbedding them in animal
charcoal contained in an earthen or iron box; see CASE-HARDENING; after
which they are brightened by heating and agitating them with bran, and
finally tempered by exposure to a regulated temperature upon a hot iron
plate. Hooks for salt-water fishing are frequently tinned, to prevent
them wearing rapidly away in rust. See TIN PLATE.


FLAKE WHITE; is the name sometimes given to pure white-lead.


FLAME (_Flamme_, Fr. and Germ.); is the combustion of an explosive
mixture of an inflammable gas or vapour with air. That it is not, as
many suppose, combustion merely at the exterior surface, is proved by
plunging a fragment of burning phosphorus or sulphur into the centre of
a large flame of alcohol. Either of these bodies will continue to burn
there with its peculiar light; thus proving that oxygen is mixed with
the whole of the burning vapour. If we mix good coal gas with as much
atmospheric air as can convert all its carbon into carbonic acid, the
mixture will explode with a feeble blue light; but if we mix the same
gas with a small quantity of air, it will burn with a rich white flame.
In the latter case, the carbonaceous particles are precipitated, as Sir
H. Davy first showed, in the interior of the flame, become incandescent,
and constitute white light: for from the ignition of solid matter alone
can the prismatic rays be emitted in that concentrated union. Towards
the interior of the flame of a candle, a lamp, or a gas jet, where the
air is scanty, there is a deposition of solid charcoal, which first by
its ignition, and afterwards by its combustion, increases in a high
degree the intensity of the light. If we hold a piece of fine wire gauze
over a jet of coal gas close to the orifice, and if we then kindle the
gas, it will burn above the wire with its natural brilliancy; but if we
elevate the gauze progressively higher, so as to mix more and more air
with it before it reaches the burning point, its flame will become
fainter and less white. At a certain distance it becomes blue, like that
of the above explosive mixture. Since the combustion of all the
constituents is in this case direct and complete, the heat becomes
greatest in proportion nearly as the light is diminished. If a few
platina wires be held in that dim flame they will grow instantly white
hot, and illuminate the apartment. On reversing the order of this
experiment, by lowering progressively a flat piece of wire gauze from
the summit towards the base of a gas flame, we shall find no charcoal
deposited at its top, because plenty of air has been introduced there to
convert all the carbon of the gas into carbonic acid, and therefore the
apex is blue; but as we descend, more and more charcoal will appear upon
the meshes. At the very bottom, indeed, where the atmospheric air
impinges upon the gauze, the flame is again blue, and no charcoal can
therefore be deposited.

The fact of the increase of the brilliancy and whiteness of flame by the
development and ignition of solid matter in its bosom, illustrates many
curious phenomena. We can thus explain why olefiant gas affords the most
vivid illumination of all the gases; because, being surcharged with
charcoal, its hydrogen lets it go in the middle of the flame, as it does
in an ignited porcelain tube, whereby its solid particles first get
ignited to whiteness, and then burn away. When phosphorus is inflamed,
it always yields a pure white light, from the ignition of the solid
particles of the snowy acid thus produced.

In the blowpipe, the inner blue flame has the greatest heat, because
there the combustion of the whole fatty vapour is complete. The feeble
light of burning hydrogen, carbonic oxide, and sulphur, may, upon the
principles now expounded, be increased by simply placing in them a few
particles of oxide of zinc, slender filaments of amianthus, or fine
platina wire. Upwards of twenty years ago, I demonstrated in my public
lectures in Glasgow, that by narrowing the top of a long glass chimney
over an argand flame either from oil or coal gas, the light could be
doubled, at the same cost of material. The very tall chimneys used by
the Parisian lampists are very wasteful. I find that with a narrow
chimney of half the length of theirs, I can have as good a light, and
save 30 per cent. of the oil. Thus the light of a flame may be increased
by diminishing its heat, or the intensity of its combustion; and
conversely the heat of a flame may be increased by diminishing its
light.


FLANNEL; a plain woollen stuff of a rather open and slight fabric.


FLAX. By this term we understand the _bast_ or inner bark of the _Linum
usitatissimum,_ which is spun into yarn for weaving linen webs. This
plant blossoms in June or July, and commonly ripens its seeds in
September. As varieties, we distinguish the _spring_ flax, with short
knotty stems, whose seed capsules at the period of maturity, spring open
with a perceptible sound; and the _close_ flax, with longer smoother
stems, whose capsules give out their seeds only when threshed. The
Germans, who have bestowed much attention upon the culture of flax, call
the former _Klanglein_ or _Springlein_, and the latter _Dreschlein_.
This is the kind most commonly grown, but from the difference of
climate, soil, and culture, it affords flax of very different qualities.
The best ground for this plant is an open, somewhat friable clay,
mingled with sand and mould. The early flax is usually sown in the end
of April or beginning of May, the late, in June. The seeds ought to be
sown thick, whereby the stalks are forced to grow more slender, and the
fibres of the bast or harl are not only smoother and finer, but more
uniform in length. If the raising of seed be the principal object, the
flax must be more thinly sown, whereby it will produce stronger stalks,
but more knotty, with shorter fibres, and more productive of tow.

Whenever the flax is ripe, which is shown by the bottom of the stalk
becoming yellow, and the leaves beginning to drop off, it must be
immediately reaped by pulling it up by the roots. The seeds are still
immature, fit merely for the oil press, and not for sowing. When the
seed crop is the object, the plant must be suffered to acquire its full
maturity; in which case the fibres are less fine and soft.

The flax is carried off the field in bundles to be rippled, or stripped
of its seeds, which is done by drawing it by handfuls, through an iron
comb with teeth eight inches long, fixed upright in a horizontal beam.
When the seeds are more fully ripened, they may be separated by the
threshing mill.

The operations next performed upon the flax, will be understood by
attending to the structure of the stem. In it, two principal parts are
to be distinguished; the woody heart or boon, and the _harl_ (covered
outwardly with a fine cuticle), which encloses the former like a tube,
consisting of parallel lines. In the natural state, the fibres of the
harl are attached firmly not only to the boon, but to each other by
means of a green or yellowish substance. The rough stems of the flax
after being stripped of their seeds, lose in moisture by drying in warm
air, from 55 to 65 per cent. of their weight; but somewhat less when
they are quite ripe and woody. In this dry state, they consist in 100
parts of from 20 to 23 per cent. of _harl_, and from 80 to 77 per cent.
of boon. The latter is composed upon the average of 69 per cent. of a
peculiar woody substance, 12 per cent. of a matter soluble in water, and
19 per cent. of a body not soluble in water, but in alkaline lyes. The
_harl_ contains at a mean 58 per cent. of pure flaxen fibres, 25 parts
soluble in water (apparently extractive and albumen), and 17 parts
insoluble in water, being chiefly gluten. By treating the harl with
either cold or hot water, the latter substance is dyed brown by the
soluble matter, while the fibres retain their coherence to one another.
Alkaline lyes, and also, though less readily, soap water, dissolve the
gluten, which seems to be the cement of the textile fibres, and thus set
them free.

The cohesion of the fibres in the rough harl is so considerable that by
mechanical means, as by beating, rubbing, &c., a complete separation of
them cannot be effected, unless with great loss of time, and rupture of
the filaments. This circumstance shows the necessity of having recourse
to some chemical method of decomposing the gluten. The process employed
with this view is a species of fermentation, to which the flax stalks
are exposed; it is called _retting_, a corruption of rotting, since a
certain degree of putrefaction takes place. The German term is
_rusting_. This is the first important step in the preparation of flax.
After the retting is completed, the boon of the stalks must be removed
by the second operation called _breaking_, and other subordinate
processes. The harl freed from the woody parts contains still a
multitude of fibres, more or less coherent, or entangled, and of
variable lengths, so as to be ill adapted for spinning. These are
removed by the _heckle_, which separates the connected fibres into their
finest filaments, removes those that are too short, and disentangles the
longer ones.

I. _Of retting._--The fermentation of this process may be either
rendered rapid by steeping the flax in water, or slow by using merely
the ordinary influence of the atmospheric damp, dews, and rain. Hence
the distinction of water-retting and dew-retting. Both may also be
combined.

Prior to being retted, the flax should be sorted according to the length
and thickness of its stalks, and its state of maturity; the riper the
plant, the longer must the retting last. The due length of the process
is a point too little studied.

_Water-retting._--When flax stalks are macerated in water, at a
temperature not too low, fermentation soon begins, evinced in the dingy
infusion, by disengagement of carbonic acid gas, and the production of
vinegar. If the flax be taken out at the end of a few days, dried, and
rubbed, the textile filaments are found to be easily separable from each
other. By longer continuance of the steep, the water ceases to be acid,
it becomes to a certain degree alkaline, from the production of ammonia,
diffuses a fetid odour, from the disengagement of sulphuretted hydrogen
gas, along with the carbonic acid; the acetous fermentation being in
fact now changed into the putrid. The filaments become yellowish brown,
afterwards dark brown and lose much of their tenacity, if the process be
carried further.

When the operation is conducted with discernment, the water-retting may
be completed by the acetous fermentation alone, as the putrefaction
should never be suffered to proceed to any length; because when
over-retted, flax is partially rotten, gets a bad colour, and yields a
large proportion of tow.

For water-retting, the flax must be bound up in sheaves, placed in
layers over each other in the water, or sometimes upright, with the
roots undermost. Straw may be put below to keep it from touching the
ground, and boards may be laid upon the top, with weights to hold it
immersed about a foot beneath the surface, especially when the
fermentative gases make it buoyant. As soon as it sinks at the end of
the fermentation, it must be inspected at least twice a day, and samples
must be taken out to see that no over-retting ensues. A single day too
long often injures the flax not a little. We may judge that the retting
is sufficient when the harl separates easily from the boon by the
fingers, when the boon breaks across without bending, and when several
stalks knotted together sink to the bottom upon being thrown into the
water. For this completion, a shorter or longer time is required
according to the quality of the flax, the temperature, &c., so that the
term may vary from five to fourteen days. It may be done either in
running or in stagnant water. For the latter purpose, tanks five feet
deep are dug in the ground. In stagnant water, the process is sooner
finished, but it is more hazardous, and gives a deeper stain to the
fibres, than in a stream, which carries off much of the colour. The best
place for steeping flax is a pond with springs of water at its bottom;
or a tank into which a rivulet of water can be occasionally admitted,
while the foul water is let off. For every fresh quantity of flax, the
pond should be emptied, and supplied with clear water. Water impregnated
with iron, stains flax a permanent colour, and should therefore never be
used. After retting, the flax should be taken out without delay, rinsed
in clean water, and exposed in an airy situation to dry by the sun.

Rough rippled flax stalks, well seasoned before being retted, and dried
afterwards, show a loss of weight, amounting to 20 or 30 per cent.,
affecting both the boon and the harl. This loss is greater the finer the
stems, and the longer the retting. The harl contains, beside the textile
filaments, a certain portion of a glutinous cement; but nothing soluble
in water. The destruction of the gluten cannot be pushed to the last
point by steeping, without doing an essential injury to the filaments.

_Dew-retting._--The fetid and noxious exhalations which the
water-retting diffuses over an extensive district of country, and the
danger of over-retting in that way, especially with stagnant water, are
far from recommending that process to general adoption. Dew-retting
accomplishes the same purpose, by the agency of the air, dews, and rain,
in a much more convenient, though far slower manner. The flax, with this
view, should be spread out thin upon meadow or grass lands, but never
upon the bare ground, and turned over, from time to time, till the
stems, on being rubbed between the fingers, show that the harl and the
boon are ready to part. The duration of dew-retting is, of course, very
various, from 2 to 6, or 8 weeks, as it depends upon the state of the
weather; a moist air being favourable, and dry sunshine the reverse. The
loss of weight by dew-retting is somewhat less than by water-retting;
and the textile fibres are of a brighter colour, softer and more
delicate to the touch.

_Mixed retting._--This may be fairly regarded as the preferable plan,
the retting being begun in the water, and finished in the air. The flax
should be taken out of the steep whenever the acetous fermentation is
complete, before the putrid begins, and exposed, for 2 or 3 weeks, on
the grass.

II. _The breaking_ is performed by an instrument called a brake. In
order to give the wood or boon such a degree of brittleness as to make
it part readily from the harl, whereby the execution of this process is
rendered easy, the flax should be well dried in the sun, or what is more
suitable to the late period of the year, in a stove. Such is often
attached to the bakers’ ovens in Germany, and other flax-growing
countries. The drying temperature should never exceed 120° F., for a
higher heat makes it brittle, easy to tear, and apt to run into tow.
Before subjecting the flax to the brake, the stems should be equalized
and laid parallel by the hand, and the entangled portions should be
straightened with a coarse heckle. The brake has one general
construction, and consists of two principal parts, the frame or case,
and the sword or beater. In the simplest brakes, the frame _e_, _fig._
412., is a piece of wood cleft lengthwise in the middle, supported by
the legs _a_ and _c_. The sword _f_, also of hard wood, is formed with
an edge beneath, and turns round the centre of motion at _q_, when
seized by the handle _h_, and moved up and down. As it descends, the
sword enters the cleft of the frame, and breaks the flax stalks laid
transversely upon it, scattering the boon in fragments.

[Illustration: 412 413 414]

But those hand brakes are more convenient which are provided with a
double cleft, or triple row of oblong teeth; with a double sword. This
construction will be understood by inspecting _figs._ 412, 413, 414.
_Fig._ 412. is the section of that side at which the operative sits;
_fig._ 413. is a section in the line A, B, of _fig._ 412; and _fig._
414., the ground plan. The whole machine is made of hard wood, commonly
red beech. Two planks, _a_ and _c_, form the legs of the implement. _a_
is mortised in a heavy block, to give the brake a solid bearing; two
stretchers _d_, bind _a_ and _c_, firmly together. The frame _e_
consists of three thin boards, which are placed edgewise, and have their
ends secured in _a_ and _c_. The sword _f_ is a piece of wood, so
chamfered from _i_ to _k_, that it appears forklike, and embraces the
middle piece of the frame; its centre of motion is the wooden pin _q_;
in front is the handle _h_, which the operative seizes with the right
hand. Both the lathes of the frame, and those of the sword are
sharpened, from _l_ to the front end, as is best shown in _fig._ 413.;
but the edges must not be too sharp, for fear of injuring the flax; and,
for the same reason, the sword should not sink too far between the
lathes of the frame. Such hand-brakes are laborious in use, and often
tear the harl into tow. The operative, usually a female, in working the
brake, seizes with her left hand a bundle of flax, lays it transversely
across the frame, and strikes it smartly with repeated blows of the
sword, pushing forwards continually new portions of the flax into the
machine. She begins with the roots, turns next round the tips, then goes
on through the length of the stalks. Flax is frequently exposed twice to
the brake, with a stove drying between the two applications.

[Illustration: 415 416 417]

The brake machines afford a far preferable means of cleaning flax than
the above hand tools. The essential part of such a machine, consists in
several deeply fluted rollers of wood or iron, whose teeth work into
each other, and while they stretch out the flaxen stalks betwixt them,
they break the wood or boon, without doing that violence to the harl
which hand mechanisms are apt to do. The following may be regarded as
one of the best constructions hitherto contrived for breaking flax.
_Fig._ 415. is a view of the right side of this machine. _Fig._ 416.,
the view from behind, where the broken flax issues from between the
rollers. The frame is formed by the two side pillars or walls _a_, _a_,
which are mortised into the bottom _b_, _b_; and are firmly fixed to it
by braces. Two transverse rods _d_, _d_, secure the base, two others _d´
d´´_, the sides. In each of these a lateral arm _e_, is mortised in an
oblique direction; a cross bar _f_, unites both arms. _Fig._ 417. shows
the inside of the left side of the frame, with the subsidiary parts. The
three rollers _g_, _i_, _k_, may be made of red beech, with iron
gudgeons, and fluted in their length, each of the flutes being 5/12 of
an inch broad, and 4/12ths deep. The large roller _g_, bears upon the
right side, a handle _h_, which on being turned, sets the whole train in
motion. The side partitions _a_, _a_, are furnished with brasses in
whose round holes _l_, _g_, _fig._ 417., the gudgeons _g_ work. For the
extremities of the two smaller rollers, there are at _a_ and _e_, slots
in brasses, as may be seen in _fig._ 415. Within the partition _a_,
there are movable brasses _l_, for the pivots of _i_ and _k_, shewn in
_fig._ 417. Each brass slides in a groove, between two ledges. A strong
cord made fast at _m_ to the partition _a_, runs over the brass of _i_,
next over that of _k_, then descends perpendicularly, and passes over
the cross bar _n_, _fig._ 415. and 416. This construction being repeated
at both ends of the rollers, the rod _n_, binds both cords. Against the
cross bar _d´_ of the frame, a lever _o_ is sustained, which lies upon
the rod _n_, and carries a weight _p_. The farther or nearer this weight
hangs towards the end of the lever, it stretches the cord more or less,
and presses by means of the brasses _l_, the rollers _i_, _k_, towards
the main roller _g_. A table _q_, serves for spreading out the flax to
be broken, and a second one _r_, for the reception of the stalks at
their issuing from between the rollers. Both tables hang by means of
iron hooks to rings of the frame _s_, _t_, _fig._ 415. and 417., and are
supported by the movable legs _u_, _u_, _u_, _fig._ 415. and 416. In
using the machine the operative lays an evenly spread handful of flax
upon the table _q_, introduces their root ends with his left hand
between the rollers _g_ and _i_, and turns round the handle _h_, with
the right. The stems are first broken betwixt _g_ and _i_, then between
_g_ and _k_, and come out upon the table _r_. The handle is moved
alternately forwards and backwards, in order that the flax may be rolled
alternately in the same directions, and be more perfectly broken. The
boon falls down in very small pieces, and the harl remains expanded in
parallel bands. This should be drawn over the points of a heckle, then
laid for a couple of days in a cellar to absorb some moisture, and
afterwards worked once more through the machine, whereby the flax
acquires a peculiar softness.

The advantages of this brake machine are chiefly the following:--

It takes up little room, and from its simplicity is easily and cheaply
constructed; it requires no more power to work, than the ordinary
hand-brake; it tears none of the filaments, and grinds nothing except
the boon, in consequence of the flutings of the rollers going much less
deep into each other, than the sword of the hand-brake; it prevents all
entanglements of the flax, whence in the subsequent heckling the
quantity of short fibres or tow is diminished; and it accomplishes the
cleaning of even the shortest flax, which cannot be well done by hand
machines.

The comminution of the boon of the stems, which is the object of the
breaking process, can however be performed by threshing or beating,
although in this way the separation of the woody matter from the textile
fibres is much less completely effected.

[Illustration: 418]

It is the practice in Great Britain, instead of breaking, to employ a
water-driven wooden mallet, between which and a smooth stone the flax is
laid. In that part of Belgium where the preparation of flax has been
studied, the brake is not used, but beating by means of the
_Bott-hammer_, to the great improvement, it is said, of the flax. The
_Bott-hammer_, _fig._ 418., is a wooden block, having on its under face,
channels or flutings, 5 or 6 lines deep, and it is fixed to a long bent
helve or handle. In using it, a bundle of the dried flax stalks is
spread evenly upon the floor, then powerfully beaten with the hammer,
first at the roots, next at the points, and lastly in the middle. When
the upper surface has been well beat in this way, it is turned over,
that the under surface may get its turn. The flax is then removed, and
well shaken to free it from the boon.

[Illustration: 419]

By the brake or the hammer the whole wood is never separated from the
textile fibres, but a certain quantity of chaffy stuff adheres to them,
which is removed by another operation. This consists either in rubbing
or shaking. The rubbing is much practised in Westphalia, and the
neighbouring districts. In this process, the operative lays the rubbing
apron on a piece of dressed leather, one foot square, upon her knee;
then seizes a bundle of flax in the middle with her left hand, and
scrapes it strongly with the _Ribbe-knife_ held in her right, _fig._
419. This tool, which consists of a wooden handle _s_, and a thin iron
blade _r_, with a blunt and somewhat bent edge, acts admirably in
cleaning and also in parting the filaments, without causing needless
waste in flax previously well broken.

The winnowing, which has the very same object as the rubbing, is,
however, much more generally adopted than the latter. Two distinct
pieces of apparatus belong to it, namely, the _swing-stock_ and the
_swing-knife_. The first consists of an upright board with a groove in
its side, into which a handful of flax is so placed that it hangs down
over half the surface of the board. While the left hand holds the flax
fast above, the right carries the swing-knife, a sabre-shaped piece of
wood from 1-1/2 to 2 feet long, planed to an edge on the convex side,
and provided with a handle. With this knife the flax is struck parallel
to the board, with perpendicular blows, so as to scrape off its woody
asperities. The breadth of the swing-knife is an important circumstance;
when too narrow it easily causes the flax to twist round it, and thereby
tears away a portion of the fibres. When 8 or 10 inches broad, it is
found to act best. Knives made of iron will not answer, for they injure
the filaments.

[Illustration: 420 421]

_Figs._ 420, 421. show the best construction of the swing-stock. The
board _a_ has for its base a heavy block of wood _b_, upon which two
upright pins _e e_, are fixed. The band _f_, which is stretched between
the pins, serves to guide the swing-knife in its movements, and prevent
the operative from wounding his feet. The under edge of the groove _c_,
upon which the flax comes to be laid, is cut obliquely and rounded off
(see _d_ in _fig._ 420.); thus we perceive that the swing-knife can
never strike against that edge, so as to injure the flax.

[Illustration: 422]

_Fig._ 422. exhibits the form of a very convenient implement which is
employed in Belgium instead of the swing-knife. It is a sort of wooden
hatchet, which is not above two lines thick, and at the edge _g h_ is
reduced to the thickness of the back of a knife. The fly _k_ gives force
to the blow, and preserves the tool in an upright position. The short
flat-pressed helve _i_ is glued to that side of the leaf which in
working is turned from the swing-stock; and is, moreover, fastened with
a wooden pin.

The rubbing and swinging throw off the coarsest sort of tow, by
separating and shaking out the shortest fibres and those that happen to
get torn. That tow is used for the inferior qualities of sacking, being
mixed with many woody fibres.

We may in general estimate that 100 pounds of the stalks of retted flax,
taken in the dry state, afford from 45 to 48 pounds of broken flax, of
which, in the swinging or scutching, about 24 pounds of flax, with 9 or
10 pounds of scutch tow are obtained. The rest is boon-waste. The
breaking of 100 pounds of stalks requires, in the ordinary routine of a
double process by hand, about 20 hours; and with the above described
machine, from 17 to 18 hours. To scutch 100 pounds of broken flax clean,
130 hours of labour are required by the German swinging method.

[Illustration: 423]

Mr. Bundy obtained a patent in 1819, for certain machinery for breaking
and preparing flax, which merits description here. _Fig._ 423. A A A A,
is the frame made either of wood or metal, which supports the two
conical rollers B and C. These revolve independently of each other in
proper brass bearings. A third conical roller D is similarly supported
under the top piece E of the machine. All these rollers are _frusta_ of
cones, made of cast iron. Whatever form of tooth be adopted, they must
be so shaped and disposed with regard to each other as to have
considerable play between them, in order to admit the quantity of flax
stem which is intended to be broken and prepared. The upper piece E of
the machine which carries the upper conical roller D, is fixed or
attached to the main frame A A A A by strong hinges or any other
moveable joint at G, and rods of iron or other sufficiently strong
material; H H is attached at its upper end by a joint to the top piece
E, through a hole near I, and is fixed at its lower end by another joint
K to the treadle or lever K L, which turns upon the joint or hinges M. A
spring or weight (but the former is preferable for many reasons) is
applied to the machine in such manner, that its action will always keep
the upper piece E, and consequently the upper roller D, in an elevated
or raised position above the rollers B and C, when the machine is not in
action; and of course the end L of the treadle will also be raised,
which admits of the flax to be worked being introduced between the
rollers, viz. over the two lower rollers B, C, and under the upper
roller D; such a spring may be applied in a variety of ways, as between
the top piece E, and the top or platform of the machine at N; or it may
be a strong spiral wire spring, having its upper end fastened to the
platform while its lower extremity is fixed to the rod H H, round which
it coils as shown at O, or it may be placed under the end L of the
treadle; but in every case its strength must be no more than will be
just sufficient to raise the upper roller D about two inches from the
lower rollers, otherwise it will occasion unnecessary fatigue to the
person working the machine.

The manner of using it is as follows: the upper and lower rollers being
separated as aforesaid, a small handful of dried flax or hemp stems is
to be introduced between them, and held extended by the two hands, while
the rollers are brought together by the pressure of the foot upon the
treadle L. This pressure being continued, the flax or hemp is to be
drawn backwards and forwards by the hands between the rollers, in a
direction at right angles to their axes, and eventually withdrawn by
pulling with one hand only. The foot is now to be removed until the flax
or hemp is again replaced, and each end is this way to be drawn several
times through the machine, until such ends are respectively finished.

By a succession of these operations, using the pressure of the foot upon
L, each time that the flax or hemp is introduced between the rollers,
and regulating such pressure according to the progress of the work, the
flax or hemp will soon be sufficiently worked, and the fibre brought
into a clean and divided state fit for bleaching; or if it be required
to spin it in the yellow state, it may be made sufficiently fine by a
longer continuation of the same process, particularly if worked between
the smaller ends of the rollers.

[Illustration: 423*]

Indeed, the operation may be commenced and continued for some time, with
the larger part of the rollers, and finished with their smaller ends;
and, in this point of view, the invention of conical rollers will be
found both convenient and useful; for as the flutes, grooves, or teeth,
vary in their distance from each other at all points between the large
and small ends, so it becomes almost impossible for the workman to draw
the flax or hemp through such rollers in the same track; and thus the
breaking of the boon must be much more irregular, and the fibre will be
much more effectually cleansed than it can be by the flutes, grooves, or
teeth of cylinders, or other such contrivances formerly employed;
because they would probably fall frequently upon the same points of the
fibres. If it is intended that the flax shall be bleached before it is
spun, then the second part of Mr. Bundy’s invention may be had recourse
to, which consists in moving certain trays or cradles in the water, or
other fluid used for bleaching the flax or hemp, in the manner
following, viz.: The flax or hemp, after having been broken and worked
in the machine, should be divided into small quantities of about one
ounce each, and these should be tied loosely in the middle with a
string, and in this state laid in the trays or cradles, and then be
soaked in cold soft water for a day or two, when each parcel should be
worked separately, while wet, through a machine, precisely similar to
that already described, except only that the rollers should be
cylindrical, and made entirely of wood with metal axles, and the teeth,
which will be parallel, should be similar in form to those shown in
section at Q, _fig._ 423*. Such operation will loosen the gluten and
colouring matter, for the rinsing and wringing which must follow. The
flax must then be again disposed in a flat and smooth manner, in such
trays or cradles, and once more set to soak in sufficient soft water to
cover it, in which a small quantity of soap, in the proportion of about
seven pounds of soap to each hundred weight of flax, has been previously
dissolved, and in this state it should remain for two or three days
longer, and then be finally worked through the machine, rinsed with
clear water, and wrung; which will render it sufficiently white for most
purposes.

III. _The Heckling._--We have already stated that, by the operation of
heckling, a three-fold object is proposed: 1. the parting of the
filaments into their finest fibrils; 2. the separation of the short
fibres which are unfit for spinning; 3. the equable and parallel
arrangements of the long filaments. The instrument of accomplishing
these objects is a comb-fashioned tool, called the _heckle_ or _hackle_;
a surface studded more or less thickly with metal points, called heckle
teeth; over which the flax is drawn in such a way that the above three
required operations may be properly accomplished.

[Illustration: 424 425]

The common construction of the heckle is the following: (see _fig._
424.) _Fig._ 424. is the ground plan, and _fig._ 425. is the section.
Upon an oblong plank _a b_, two circular or square blocks of wood _c_
and _d_ are fixed, in which the heckle teeth stand upright. To give
these a firmer hold they are stuck into holes in a brass or iron plate,
with which the upper surface of _c_ and _d_ is covered. Both heckles may
be either associated upon one board or separated; and of different
finenesses; that is, the teeth of the one may be thinner, and stand
closer together; because the complete preparation of the flax requires
for its proper treatment, a two-fold heckling; one upon the coarse, and
one upon the fine heckle; nay, sometimes 3 or 4 heckles are employed of
progressive fineness. The heckle teeth are usually made of iron,
occasionally of steel, and from 1 to 2 inches long. Their points must be
very sharp and smooth, all at an equal level, and must all graduate very
evenly into a cylindrical stem, like that of a sewing needle, without
any irregularity. The face of the heckle block must be uniformly beset
with teeth, which is done by different arrangements, some persons
setting them in a circle, and others in parallel rows; the former being
practised in Germany, the latter in England. The coarse heckle is
furnished with teeth about one tenth of an inch thick, one and a quarter
of an inch long, and tapering from the middle into a very fine point. In
the centre of the circular heckle is a tooth planted; the rest are
regularly set in 12 similar concentric circles, of which the outermost
is 5-3/4 inches in diameter. The fine heckles contain no fewer than 1109
teeth. Instead of making the points of the teeth round, it is better to
make them quadrangular, in a rhombus form, in which case the edges serve
to separate or dissect the fibres.

The operation of heckling is simple in principle, although it requires
much experience to acquire dexterity. The operative seizes a flock of
flax by the middle with the right hand, throws it upon the points of the
coarse heckle, and draws it towards him, while he holds the left hand
upon the other side of the heckle, in order to spread the flax, and to
prevent it from sinking too deeply among the teeth. From time to time
the short fibres or tow sticking to the teeth are removed. Whenever one
half of the length of the strake of flax is heckled, it is turned round
to heckle the other half. This process is repeated upon the fine heckle.
From 100 pounds of well-cleaned flax, about 45 or 50 pounds of heckled
flax may be obtained by the hand labour of 50 hours; the rest being tow,
with a small waste in boony particles and dust. The process is
continued, till by careful handling little more tow is formed.

Many contrivances have been made to heckle by machinery, but it may be
doubted whether any of them as yet make such good work with so little
loss as hand labour. In heckling by the hand, the operative feels at
once the degree of resistance, and can accommodate the traction to it,
or throw the flax more or less deep among the teeth, according to
circumstances, and draw it with suitable force and velocity. To aid the
heckle in splitting the filaments, three methods have been had recourse
to; beating, brushing, and boiling with soap-water, or an alkaline lye.

Beating flax either after it is completely heckled, or between the first
and second heckling, is practised in Bohemia and Silesia. Each heckled
tress of flax is folded in the middle, twisted once round, its ends
being wound about with flaxen threads; and this head, as it is called,
is then beat by a wooden mallet upon a block, and repeatedly turned
round till it has become hot. It is next loosened out, and rubbed well
between the hands. The brushing is no less a very proper operation for
parting the flax into fine filaments, softening and strengthening it
without risk of tearing the fibres. This process requires in tools,
merely a stiff brush made of swines’ bristles, and a smooth board, 3
feet long and one foot broad, in which a wooden pin is made fast. The
end of the flax is twisted two or three times round this pin to hold it,
and then brushed through its whole length. Well heckled flax suffers no
loss in this operation; unheckled, only a little tow; which is of no
consequence, as the waste is thereby diminished in the following
process. A cylindrical brush turned by machinery might be employed here
to advantage.

The boiling of flax with potash lye alone, or with lye and soap,
dissolves that portion of the glutinous cement which had resisted the
retting, completes the separation of the fibres, and is therefore a good
practical means of improving flax. When it is performed upon the heckled
fibres, a supplementary brushing is requisite to free it from the dust,
soapy particles, &c.

_Can flax be prepared without retting?_--The waste of time and labour in
the steeping of flax; the dyeing of the fibres consequent thereon, which
must be undone by bleaching; the danger of injuring the staple by the
action of putrescent water; and, lastly, the diminished value of flax
which is much water-retted, are all circumstances which have of late
years suggested the propriety of superseding that process entirely by
mechanical operations. It was long hoped, that by the employment of
breaking machines, the flax merely dried could be freed from its woody
particles, while the textile filaments might be sufficiently separated
by a subsequent heckling. Experience has, however, proved the contrary.
The machines, which consisted for the most part of fluted rollers of
iron or wood, though expensive, might have been expected to separate the
ligneous matter from the fibres; but, in the further working of the flax
no advantage was gained over the water-retting process.

1. Unretted flax requires a considerably longer time for breaking than
retted, under the employment of the same manipulations.

2. Unretted stalks deliver in the breaking and heckling a somewhat
greater product than the same weight of flax which has been retted; but
there is no real advantage in this, as the greater weight of the
unretted flax consists in the remainder of ligneous or glutinous matter,
which being foreign to the real fibre, must be eventually removed. In
the bleaching process, the water and the alkaline lyes take away that
matter, so that the weight of the bleached fibre is not greater from the
unretted than the retted flax.

3. The parting of the fibres in the unretted stalks is imperfectly
effected by the heckling, the flax either remains coarser as compared
with the retted article, and affords a coarser thread, or if it be made
to receive greater attenuation by a long continued heckling, it yields
incomparably more torn filaments and tow.

4. The yarn of unretted flax feels harder, less glossy, and rougher;
and, on account of these qualities, turns out worse in the weaving than
the retted flax. Nor is the yarn of unretted flax, whether unbleached or
bleached, in any degree stouter than the yarn of the retted flax.

5. Fabrics of unretted flax require for complete bleaching about a sixth
less time and materials than those of the retted. This is the sole
advantage, but it is more than counterbalanced by the other drawbacks
above specified.

In Mr. Wordsworth’s improved apparatus for heckling flax and hemp, a
succession of stricks is subjected to the operation of several series of
revolving heckles of different degrees of fineness, for the purpose of
gradually separating or combing the long fibres, and dressing them
smooth; while at the same time, the tow or entangled refuse portions of
the material taken off from the stricks by the heckle points are removed
from the heckles by rotatory brushes and rollers covered with wire
cards, and discharged into suitable receivers, whence it may be taken to
a carding engine, to be worked in the ordinary way.

[Illustration: 427]

The accompanying figures represent in plan and section, the heckling
machine which is made double, for the purpose of allowing two series of
stricks of flax to be acted upon at one time. _Fig._ 426. is a
horizontal view of the machine; _fig._ 427. is an end view, the whole
being represented in working order, and the respective letters of
reference pointing out corresponding parts of the machine.

[Illustration: 427]

A A are two large barrels or drums, upon the surfaces of which are fixed
longitudinally several series of brass ribs _a_, _b_, _c_, _d_, _e_,
_f_, _g_, _h_, _i_, holding heckle points. These ribs are placed at
small distances apart round the barrels, all the heckle points standing
radially from the axes, and the barrels are mounted upon axles supported
by pedestals, with plummer blocks bearing on the rails of the end
frames. B B, are two horizontal wheels or pulleys turning upon vertical
shafts, which pulleys conduct an endless chain C C C C, carrying the
holders, whereon the stricks of flax or other material intended to be
heckled are suspended.

At one end of the axle of each of the barrels a toothed wheel D D, is
made fast, and these are connected by a similar wheel E, and a pinion
F, _fig._ 427., the latter being fixed upon the axle of the driving
rigger G.

The power of a steam engine, or any other first mover, being applied by
a band and rigger, or otherwise to the axle of G, the pinion F, is
driven round, which, being in geering with the toothed wheels E and D D,
causes the heckle barrels A A to revolve simultaneously in opposite
directions, as shown by the arrows in _fig._ 427.

The stricks of flax intended to be operated upon are severally confined
between pairs of clamps _k_, fastened together, which clamps, with the
stricks, are then suspended in their respective holders H H, attached to
the endless chain C: the lower portion of the flax hanging down for the
purpose of being acted upon by the rotatory heckles, while the upper
portions are turned up in loops and confined by spring levers attached
to each carrier.

The respective holders of the clamps consist of a forked frame, with
hooks at the lower parts of their arms, which receive the ends of the
clamps _k_, that confine the strick of flax. From the upper part of each
forked frame, a perpendicular pin extends, which pins when inserted into
the sockets _l l l_, in front of the chain, form axles for the frames to
turn upon at certain periods of the operation.

On the upper end of each pin, a small arm or tappet piece _m_, _fig._
427., is fixed, standing at right angles to the face of the forked frame
of the holder H. Those tappets as the endless chain conducts the holders
along at certain periods, come in contact with stationary pins or wipers
_n n_, fixed to the guide rails _o_, on which the chain C slides; and
these wipers acting against the tappets as they pass, cause the holders
to be turned round at those periods for the purpose of bringing the
reverse side of the strick of flax on to the heckle points.

Let it now be supposed, that all the holders connected to the endless
chain have been furnished with stricks of flax, or other material to be
heckled, and that the barrels A A, are put in motion in the way
described, revolving in the direction of the arrows shown in _fig._ 427.
A pinion on the end of the axles of one of the barrels A, will drive a
train of toothed geer J K L M and N, on the axle of the latter, of which
there is a bevelled pinion taking into a bevelled wheel, turning
horizontally at the lower end of the perpendicular shaft of one of the
chain pulleys. It will hence be perceived that as the barrels go round,
such rotatory motion will be communicated to the pulley B, as will cause
it to drive the chain C forward, and by that means conduct the several
stricks of flax progressively along the barrel.

When each successive holder, with its strick of flax or other material,
is brought to the part _z_, _fig._ 426., the fibres come in contact with
the rotatory barrel, and first strike upon the series of coarse heckles
_a a_, placed upon an inclined or conical surface of the barrel, by
which means the lower ends of the flax in each strick are first acted
upon; and as it advances, the upper part, and ultimately the whole
length of the long fibres of the suspended strick are gradually brought
on to the heckles, which progressive operation prevents the long fibres
from being broken, and causes a smaller quantity of tow to be produced
than is usually taken off in any of the ordinary modes of heckling.

After the strick of flax or other material has been carried by the
travelling chain past the first inclined or conical surface _a_, of the
heckling barrel, it then comes upon the cylindrical part _b_, of the
barrel, which is also furnished with coarse heckles that penetrate and
comb down the whole pendant lengths of the fibres. But in order that
both sides of the strick of flax may be equally operated upon, the
holder is now to be turned round upon its pin or pivot, which movement
is effected by one arm of the lever or tappet _m_, (as the carrying
chain moves onward), coming against the stationary pin or wiper _n_,
which changes the position of the holder, as shown at _p_, in the
horizontal view _fig._ 426.

The under part of the guide rail _o_, upon which the chain slides, is at
this part cut away, for the purpose of allowing the holder to turn round
horizontally; and a pin or projection at the under side of the guide
rail, as the chain continues moving, acts against the side of the
carrier frame, and forces it into a position parallel with the chain.
The other side of the strick of flax is by these means brought on to the
heckles of the second inclined or conical surface of the barrel at _c_;
and the travelling chain proceeding onward, the fibres of the material
are in succession passed over and combed by the heckles of increasing
fineness, _d_, _e_, and _f_, on the cylindrical part of the revolving
barrel, until the strick having arrived at the second wiper _n_, the
frame or holder is at _q_, turned round as before, and the reverse side
of the strick, or that first operated upon by the heckles _a_ and _b_,
is brought progressively on to the heckles of increasing fineness, _g_,
_h_, and _i_; and having passed the last series of rotatory heckles, the
holders are in succession to be removed from the machine, the material
having been sufficiently dressed.

The clamps of the holders are now opened by the attendant, and the
stricks of flax or other material are taken out, and again placed
between the clamps in reversed positions, in order that the other ends
of the fibres may be operated upon. The clamps, with the stricks, are
then suspended again in the holders, the uncombed ends of the fibres
hanging down upon the heckle barrel.

In order to avoid interrupting the continual operation of the machine,
it is proposed that the strick, on its second introduction, shall be
placed in the holders on the opposite side at _y_, which is one of the
reasons for constructing a double machine, and the strick being thence
carried along by the travelling endless chain in the way already
described, the fibres will be first brought under the operation of the
coarse heckles on the inclined or conical surface of the second
revolving barrel, and then of the other heckles increasing in fineness
on the cylindrical part of the barrel, until having reached the end, as
in the former instance, the fibres of the flax may be considered to be
sufficiently dressed, and may then be withdrawn.

It may be necessary here to remark, that as different kinds and
qualities of material will require different degrees of working by the
heckles, this can be effected by varying the comparative speeds of the
travelling holders and the heckle barrels. These comparative speeds, it
will be perceived, depend upon the diameters of the wheels and pinions
by which the pulley B is driven from the rotation of the heckle barrel.
These wheels and pinions are therefore intended to be removed and
changed for others of different diameters, as circumstances may require.
It will be perceived that the faster the stricks travel through the
machine compared to the rotatory speed of the heckle barrels, so much
the less will the material be acted upon by the rotatory heckles; but as
different qualities of material must be differently operated upon,
according to circumstances, it is impossible to set out any definite
speeds or proportions of speed: that will, however, be readily perceived
by competent workmen when working at the machine.

In the process of opening the fibres of the material by the rotatory
heckles, a quantity of short or loose fibres, as tow, will be taken off
the stricks by the heckle points, and will remain adhering to the barrel
between the points of the heckles: in order, therefore, to remove this
tow, or other loose entangled materials from the heckles, several series
of brushes, or blocks, with bristles, are affixed longitudinally to
rotatory barrels Q Q.

These brush barrels are mounted parallel to the heckle barrels upon
axles, supported in plummer blocks affixed to brackets extending from
the end frames of the machine. Those parts of the brush barrels which
are opposite to the cylindrical portions of the heckle barrel are
cylindrical, and those parts which are opposite to the bevels are
contra-bevelled, or made as frustums of cones reversed, or in an
opposite angle, as _r_, _s_, so as to run parallel to the inclined
surfaces of the heckle barrels _a_ and _c_.

Upon the periphery of these barrels Q Q, ribs or blocks, with bristles
or brushes, are fixed longitudinally, at suitable distances apart, the
bristles all standing radially from the axle, and taking into the points
of the heckles.

Rotatory motions are given to the brush barrels Q Q, by bands passing
from the riggers at G, over pulleys R R, fixed at the end of each of the
axles of the brush barrels. Hence, it will be perceived, that the
barrels Q Q will revolve in opposite directions to the heckle barrels,
and with sufficient speed to enable the brushes to pass through between
the points of the heckles, and in so doing, to remove the tow or other
loose matter therefrom.

The tow or other loose fibrous material collected upon the brushes is
transferred thence on to wire cards placed round the periphery of the
barrels S S, which barrels are mounted upon axles parallel to the brush
rollers, and turn in plummer blocks upon brackets, extending from the
end frames of the machine.

These barrels are cylindrical, and covered with sheets of wire cards at
those parts which are opposite to the cylindrical portions of the brush
barrels, but those portions of the barrel S, which are opposite to the
bevelled points _r_ and _s_, of the brush barrels, are bevelled or made
conical at _t u_, to fit or correspond with the inclined surfaces _r_
and _s_; these are covered with sheets of wire card also.

Rotatory motions are communicated to the card barrels S S, by bands from
the pulley T, fixed on to the side of the toothed wheel M, (see _fig._
427.) which band drives similar pulleys V V, mounted upon studs fixed in
the end frame. Upon the side of each of these pulleys V V, a pinion _t_
is fixed, which pinion takes into the teeth of the wheel W, on the end
of the axle of each of the card barrels S S; by which means such slow
motions are given to the barrels S, as will allow the brushes of the
barrels Q to comb off, and deposit the tow or other fibrous material
upon the wire cards as they revolve, and from whence it is to be removed
by a doffing comb, and let fall into any convenient receptacle below, in
the same way as in ordinary carding engines.

The doffing combs, X X X, are formed to the shape of the card barrels,
and are attached to straight bars extending along the machine on both
sides, which are supported at their extremities by levers Y Y, vibrating
upon fulcrum pivots at _w w_. To these levers perpendicular rods Z Z are
connected by joints, and the lower end of each of these rods is attached
to an eccentric disk, roller or crank _x x_, on the axle of the brush
barrel; whence it will be perceived that by the rotation of the
eccentrics _x_, the levers Y will be made to vibrate and strike off, or
doff the tow or other material from the card barrels, in a similar
manner to the operations of the doffing comb of an ordinary carding
engine.

Mr. Evans’ patent improvements in machinery for preparing and dressing
flax and hemp apply, first, to the operation of scutching, swingling, or
beating away the boom or woody particles of the rind which covers the
flax, or hemp, in its rough state; and, secondly, to the subsequent
operation of heckling, combing, or opening of the fibres of the material
preparatory to spinning it into yarns.

[Illustration: 428 429]

_Fig._ 428. represents the scutching or swingling machine, in different
positions. _Fig._ 428. is an end view of the machine in operation;
_fig._ 429. is a front view of the same. The essential parts of the
machine, and those in which the invention especially consists, are two
pairs of revolving beaters or scutchers, each formed by long ribs or
blades mounted upon arms. The blades of the beaters _a a_, may be made
of ribs of hard wood, or other suitable material, broad but thin, and
slightly rounded on their edges, to prevent their cutting the fibres of
the flax or hemp when they strike it. The two blades are placed parallel
to each other, and mounted upon a hexagonal frame, the arms _b b_
inclining or forming obtuse angles with the blades, and from the middle
of the arms short axles _c c_, extend, upon which the beaters revolve.

The axles of both pairs of beaters are mounted in plummer boxes, bearing
upon horizontal rails at the ends of the machine, as shown in _fig._
428., and are at such distance apart as will allow of the arms and the
beaters of each pair passing alternately within those of the other pair
as they revolve in opposite directions, which they are enabled to do
without coming in contact, in consequence of the inclination of the
arms.

On the axle at one end of each pair of beaters a toothed wheel _d_, is
affixed, and these wheels being of similar diameters, and taking into
each other, cause the beaters to revolve with similar speed in opposite
directions, rotatory motion being given to them by a band and rigger
fixed upon one of the axles; and in order that the beaters in revolving
may not come in contact as they pass, the positions of the two pairs are
so arranged that the blades of one shall be in a perpendicular
situation, while those of the other are horizontal.

The rind of the flax or hemp having been previously broken by any of the
ordinary modes of performing that operation, small bunches or stricks of
the material are spread out, and their ends confined between the jaws of
clamps or holders.

[Illustration: 430 431]

These clamps or holders differ considerably from the clamps which are
commonly used. I shall therefore particularly describe their
construction, before showing them in operation. _Fig._ 430. and 431. are
views of the clamp in two different positions; _a_ and _b_ are two
boards united together by a hinge _c_, at top, which of course allows
them to shut and open. The lower parts, forming the jaws of the clamps,
are made with teeth or indentations, between which parts the ends of the
flax or hemp are securely held when the clamps are brought together; _d
d_, are two pieces projecting from the board _b_, at the end of each of
which is an eye shown by dots, and at the back of the board _a_, (see
_fig._ 430.,) there is a double armed lever _e_, turning upon a fixed
pin _f_, which lever carries two circular wedges _g g_. These wedges
pass into the eyes of the pieces _d d_, when the clamps are closed, and
hold them fast. There is a segment ratchet _h_, at the upper part of the
board _a_, which turns upon a stud _i_, and is pressed downward by a
spring _k_. This ratchet receives the end of the lever _e_, and
consequently keeps the circular wedges firm in the eyes, which hold the
clamps securely together, and prevents their opening by the shaking of
the machine.

When it is required to open the clamps, the ratchet _h_ must be raised,
and the lever _e_ pushed aside by its handle _l_, which draws the
circular wedges _f_ from the eyes of the pieces _d d_, and the boards of
the clamps immediately separate. For the convenience of suspending the
holders in the machines, a piece of sheet iron _m_, is bent at right
angles, and fastened to the back of the board _b_, as seen in _fig._
431., forming a groove by means of which the holders are enabled to
slide into the machine and hang there.

These clamps or holders are, when charged with the material, placed in
the scutching machine, as shown at _e e e_ in _figs._ 428. and 429.,
bearing upon the edge-rail or bar _f_. The beaters are now made to
revolve in the manner already described, by which the edges of the
blades will strike against the pendent stricks of flax or hemp
alternately on each side, and beat off, scutch or swingle the boom from
the material, and render it fit for the operation of heckling which is
to follow.

The whole machine is encased with boards, to prevent the inconvenience
arising from dust, and an apparatus might be adapted with a blower to
conduct away the dust created by the machine, and to discharge it out of
the building.

In introducing these stricks of flax or hemp into the machine, the
holder is placed upon the projecting end of the bar or edge-rail _f_,
and is thence slidden into the machine; and after the material has been
sufficiently scutched or swingled, the holders with the stricks are
removed through the top of the machine, and others successively
introduced at the end, and pushed along the rail.

If, however, it should be thought desirable, the stricks may be
progressively carried through the scutching machine, and delivered into
a similar edge-rail in the heckling machine, there to be operated upon
in the way about to be described, by which means the whole process of
scutching and heckling may go on without interruption.

[Illustration: 432]

_Fig._ 432. represents the heckling or combing machine by which the
fibres of the material are to be opened, and the tow removed. It is a
transverse section, taken nearly through the middle, in a vertical
direction. Perpendicular standards form the ends of the machine, which
are connected together by longitudinal rods or bars secured by nuts. The
heckle points intended to act upon the flax are mounted in the frames
_a_, _b_, _c_, and _d_, and the stricks of flax held in the clamps _e_,
_e_, _e_, as described, are suspended from the bar or edge-rail
extending through the machine.

In order to render the principles of this machine and its mode of
working evident, it may be desirable to show in an abstract form the
manner in which the heckles are brought into operation upon the flax,
and for this purpose two diagrams are delineated in _figs._ 433, 434.

Suppose two sets of combs or heckle points be mounted upon frames _a_
and _b_, as in these figures, each frame being moveable by means of
cranks _c_, _c_, and _d_, _d_, connected in such manner that they both
turn with the same speed in opposite directions, it is evident that
every part of the frames and combs will move in circles corresponding to
those described by the cranks; the points of the combs travelling in the
directions of the arrows, and in circles represented by dots.

[Illustration: 433 434]

During this movement, whilst performing the first descending quarter of
the circle, the cranks bring the frames together as in _fig._ 433. They
begin after this to separate in describing the second descending
quarter, and come to the position _fig._ 434., when, continuing to
revolve, they move further from each other in describing the first
ascending quarter of the circle, and arrive at the position where the
distance is the greatest; lastly, they describe the second ascending
quarter returning to the third position. If, therefore, a strick of flax
be suspended between the two sets of combs as in _fig._ 433., and the
rotatory motion be continued for a sufficient length of time, the flax
will be combed in the whole length which is submitted to the actions of
the combs, although the points severally have only operated in very
small space.

Such a system of combs or heckles would make a very good and simple
heckling engine, if it were not for the inconvenience experienced by the
points dragging some of the fibres with them when withdrawing from the
flax, which would produce a great waste of material; and to obviate this
it would be necessary to introduce some contrivance for clearing the
points, which must be attended with considerable complication. The plan,
however, of the present improved engine, affords the means of producing
the same effect by more simple and efficient means.

[Illustration: 435 436]

There are two series of combs, see _fig._ 435., attached to two movable
frames represented at _a_ and _b_. Each frame is formed by vertical bars
_a b_, with lateral branches or arms, which carry the heckle points. The
branches or arms are parallel, and at equal distances apart, but fixed
in such positions in each frame that they may occupy the intervening
space when the frames are brought together as _fig._ 436. The frames are
put in motion by means of revolving cranks to which they are attached,
as shown in _fig._ 436., and when the cranks turn upon their axes, the
branches of one frame pass between those of the other without touching.
This forms what may be called a set of combs; but one of the improved
machines contains two such sets, the points of the combs of one set
being opposed to the points of the combs in the other set.

The way in which the series of combs that compose one set act upon the
flax, is shown in the side view, _fig._ 435. When the cranks are nearly
vertical, the points of both frames are away from the flax, but as the
cranks move round in the direction of the arrows, the frames come into
another position, and it is then that the points or heckles of one of
the frames _a_, begin to penetrate the flax, and descending they comb or
divide its fibres. The rotation of the cranks continuing, the two frames
_a_ and _b_ come into the position shown at _fig._ 435., the points of
the frame _a_, withdrawing from the flax, and those of the frame _b_,
approaching and pushing the fibres off from the former, which are now
combed by the descending stroke of the points.

It will hence be perceived that as the combs of the frame _a_ and _b_,
respectively advance, they will push forward the whole of the strick of
flax, and render it impossible for the fibres to be raised and
entangled, as each frame in advancing clears the fibres from the points
which preceded it.

[Illustration: 437]

A single set, however, of such combs or heckles acting only on one side
of the flax, would but imperfectly perform the operation of opening its
fibres; it is therefore necessary, in order to accomplish the desired
object in the most effectual way, that two such sets of combs or heckles
should be brought to act on opposite sides of the strick of flax, which
may be done in the manner shown in the figures. The cranks of the two
opposite sets of comb-frames or heckles _a_, _b_, and _c_, _d_, are
connected by a pair of toothed wheels _e_, _f_, as _fig._ 437., or by
four toothed wheels, by which the heckles are actuated at once, the two
sets moving in opposite directions, but with similar speeds, and the
combing or heckling of the material will go on in the way shown in the
figure last indicated.

Thus far I have considered only two frames of combs or heckles
constituting a set, as acting upon each side of the strick of flax; but
in order to perform a greater quantity of work, several sets may be
mounted in one machine, working alongside of each other, extending over
the breadth of the machine. The combs may then be supported upon three
frames, of which the middle one may have branches or arms extending upon
both sides, and the other two frames branches extending inwards only. To
drive the frames so arranged they must be connected to treble cranks.

Such is the principle of the improved machine for combing or heckling,
exhibited in the several figures of which I now proceed to describe the
particular construction. The machine or engine, _fig._ 432., has four
sets of combs, acting both at the back and front of the flax; _a b_ are
the front set of combs, and _c d_, the back set of combs; _e e e_, are
the clamps holding the stricks of flax previously scutched, which clamps
hang upon the edge-rail. The comb frames are attached at top and bottom
to the cranks _g g_, which are all connected by toothed geer, and driven
by a band and rigger.

The combs or heckles being put in motion in the way described, act upon
the suspended stricks of flax, and upon their fibres, as explained;
which stricks are progressively conducted through the machine by their
clamps sliding upon the edge-rail through the agency of the endless
chain, to which the clamps are severally attached, by a hook falling
into one of the links. The chain is driven by a spur wheel upon the axle
of a bevel wheel, which receives a slow rotatory motion through a bevel
pinion on the axis of a similar wheel, actuated by another pinion on the
end of the upper crank axle. By these means, clamps, with the stricks of
flax placed on the edge-rail, are slowly carried through the machine,
when the flax will be gradually acted upon first by heckle points of a
coarse kind, set wide apart, and ultimately by finer points set near
together; after which, the clamp with the strick of flax is discharged
from the machine, at the reverse end of the edge-rail. But should the
workman neglect to remove the holder or clamp, when it arrives at the
end of the rail, the machine would be stopped by means of a jointed
lever, having a fork at its end, which pushes the band from the fast
rigger on to the loose one, and throws off the driving power.

As the combs or heckles, in acting upon the flax to divide its fibres,
tear parts of the fibres, and reduce them into tow, the downward motion
of the heckles brings the tow with them out of the flax, which is
deposited between two fluted rollers _p p_, _fig._ 432., and is by them
conducted down to the large drum _q_, where it becomes lapped in two
endless sheets round the periphery of the drum; the one of coarse tow,
the other of fine, the adhesion being assisted by a pressing roller _r_;
and when a quantity of the tow has been thus accumulated round the
periphery of the drum, it may be removed thence by cutting it off in
sheets. The fluted rollers, and also the large drum, are driven by geer
bands.

After the strick of flax has been thus carried through the scutching
machine or the heckling machine, the jaws of the clamps are to be
opened, the ends of the flax reversed, and the strick again confined in
the clamps, so that the other end of the strick may be operated upon in
a similar way. In order to prevent any part of the flax from attaching
itself to the branches of the movable frames, each frame is furnished
with a shield or guard of polished iron or brass plate, which covers a
part of the combs and the heads of the screws by which they are fixed to
the branches. When the plate metal is bent into the form of a shield, it
is slipped on to the branches of the heckle frames, and is sufficiently
elastic to hold fast.

But it is to be observed, that the edges of the shields are to vary in
the extent of their projection according to the situation in which they
are to be placed; those which are to shield the upper branches of
heckles are to project but little, so as to leave the points uncovered
and free to enter the strick of flax; but the shields of the lower
heckles are to project considerably over the points, to prevent them
from penetrating too far into the fibres, which is so contrived for the
purpose of facilitating the falling of the tow, which would otherwise be
with difficulty removed from the lower combs, were it thrust upon the
whole length of the points.

It being advantageous that each strick of flax should be combed near the
lower extremities before the middle is acted upon, it is necessary, in
order to obtain this effect, to remove some of the points of the combs
in the upper branches. By these means, the operation of the heckles upon
the flax begins and proceeds gradually, and ceases at the opposite
extremity of the machine in the same gradual way, which is very
advantageous in clearing completely the flax from the tow.

IV. _Flax spinning._--If we compare flax with other spinning materials,
such as wool and cotton, we shall find it to possess several
characteristic properties. While cotton and wool are presented by nature
in the form of insulated fibres, the former requiring merely to be
separated from its seeds, and the latter to be purified from dirt and
grease before being delivered to the spinner, flax must have its
filaments separated from each other by tedious and painful treatment.
In reference to the spinning and the subsequent operations, the
following properties of flax are influential and important:--

1. The considerable length of the fibres, which renders it difficult, on
the one hand, to form a fine, level, regular thread, on the other, gives
the yarn a considerably greater tenacity, so that it cannot be broken by
pulling out the threads from each other, but by tearing them across.

2. The smooth and slim structure of the filaments, which gives to linen
its peculiar polished aspect, and feel so different from cotton, and
especially from woollen stuffs, unless when disguised by dressing. The
fibres of flax have no mutual entanglement, whereby one can draw out
another as with wool, and they must therefore be made adhesive by
moisture. This wetting of the fibres renders them more pliant and easier
to twist together.

3. The small degree of elasticity, by which the simple fibres can be
stretched only one twenty-fifth of their natural length before they
break, while sheep’s wool will stretch from one-fourth to one half
before it gives way.

Good flax should have a bright silver gray or yellowish colour
(inclining neither to green nor black); it should be long, fine, soft,
and glistening, somewhat like silk, and contain no broad tape-like
portions, from undissevered filaments. Tow differs from flax in having
shorter fibres, of very unequal length, and more or less entangled. Hemp
agrees in its properties essentially with flax, and must be similarly
treated in the spinning processes.

The manufacture of linen and hemp yarn, and the tow of either, may be
effected by different processes; by the distaff, the hand-wheel, and
spinning machinery. It will be unnecessary to occupy the pages of this
volume with a description of the first two well known domestic
employments. I shall therefore proceed directly to describe the last
method, or

_Spinning of Flax by Machinery._--This branch of manufacture has been
much more recently brought to a practical state than the spinning of
cotton and wool by machines, of which the cause must be sought for in
the nature of flax as above described. The first attempts at the machine
spinning of flax, went upon the principle of cutting the filaments into
short fragments before beginning the operation. But in this way the most
valuable property of linen yarn, its cohesive force, was greatly
impaired; or these attempts were restricted to the spinning of tow,
which on account of its short and somewhat tortuous fibres, could be
treated like cotton, especially after it had been further torn by the
carding engine. The first tolerably good results with machinery seem to
have been obtained by the brothers Girard at Paris, about the year 1810.
But the French have never carried the apparatus to any great practical
perfection. The towns of Leeds in Yorkshire, of Dundee in Scotland, and
Belfast in Ireland, have the merit of bringing the spinning of flax by
machines into a state of perfection little short of that for which the
cotton trade has been so long celebrated.

For machine spinning, the flax is sometimes heckled by hand, and
sometimes by machinery. The series of operations is the following:--

1. The heckling.

2. The conversion of the flax into a band of parallel rectilinear
filaments, which forms the foundation of the future yarn.

3. The formation of a sliver from the riband, by drawing it out into a
narrower range of filaments.

4. The coarse spinning, by twisting the sliver into a coarse and loose
thread.

5. The fine spinning, by the simultaneous extension and twisting of that
coarse thread.

The spinning of tow requires a different treatment: we shall first treat
of the heckling of flax by machines; and secondly, of the mechanical
spinning of flax. The mechanical carding and spinning of tow are very
similar to those of cotton; which see. Though machine heckling be far
from perfect, yet the tow it throws off can be spun into very good yarn
by machines, while it would afford very indifferent yarn to the hand
spinner.

All heckle machines have this common property, that the flax is not
drawn through them, as in working by hand, but on the contrary, the
system of heckles is moved through the flax properly suspended or laid.
Differences exist in the shape, arrangement, and movements of the
heckles, as also in regard to the means by which the adhering tow is
removed from them. The simplest and most common construction is to place
the heckles upon the surface of a horizontal cylinder, while the flax is
held either by mechanical means or by the hand during its exposure to
the heckle points. Many machines have been made upon this principle. It
is proper in this case to set the heckle teeth obliquely in the
direction in which the cylinder turns, whereby they penetrate the fibres
in a more parallel line, effect their separation more easily, and cause
less waste in torn filaments. To conduct the flax upon the cylinders,
two horizontal fluted rollers of iron are employed, which can be so
modified in a moment by a lever as to present the flax more or less to
the heckling mechanism. The operator seizes a tress lock of flax with
her hand and introduces it between the fluted rollers, so that the tips
on which the operation must begin, reach the heckles first, and by
degrees the advancing flax gets heckled through two-thirds or
three-fourths of its length, after which the tress or strick is turned,
and its other end is subjected to the same process. By its somewhat
rapid revolution the heckle cylinder creates a current of air which not
only carries away the boomy particles, but also spreads out the flax
like a sheaf of corn upon the spikes, effecting the same object as is
done by the dexterous swing of the hand. The tow collects betwixt the
teeth of the heckle, and may, when its quantity has become considerable,
be removed in the form of a flock of parallel layers.

[Illustration: 438]

The essential parts of such a construction will be understood from
_fig._ 438., though the fluted rollers are absent. The flax _a_, _b_, is
held by the hand, or in a kind of clamp. The cylinder is partly covered
with a curvilinear plate of iron _c_, _d_, which serves to sustain the
flax, and to guide it in circular tresses round the periphery of the
heckle. At the beginning it is placed near _b_, when the tips of the
flax are only presented to the heckles; during the working the shield is
continually drawn back in the direction from _d_ to _c_, and thus lets
the operation be performed upon the remaining part of the flax.

[Illustration: 439]

[Illustration: 440]

[Illustration: 441]

_First operation; the conversion of flax into ribands or slivers._--This
is effected by subjecting the flax to a series of advancing gills or
heckle-teeth, and at the same time drawing out its fibres by means of
rollers. _Figs._ 439, 440, 441, show the outline of the construction of
a machine for this purpose. Here two rows of heckles are placed
alongside of each other, though only one of them be shown in the ground
plan, _fig._ 440., in order to allow the parts beneath the other to be
seen. The flax is placed in the sheet iron channels _a a_, by laying
down one handful after another, so that the points of the second strick
reach to only the middle of the first, and thus preserve a uniformity of
thickness in the feeding. This process is necessary, since, as every one
knows, the heckled stricks are always thick in the middle, and thin at
the ends. The flax being introduced between the rollers _b_ and _c_, is
drawn out by their agency, and at the same time subdivided by the
heckles _d_, between whose teeth the pins of the roller _e_ press it
down. At the rollers _f_³ it is loosened from the heckles by the
transverse bars which rise from the springs _g_, after which it is
seized by the rollers _h i_, and drawn again. A little beyond these
rollers, it runs through a funnel _l_, in order to gather the fibres
together; in front of these rollers the slivers from both rows of
heckles are united, and proceed in one riband through that polished
brass funnel; the rollers _m n_ extend this riband, pressing it gently
together, and then let it fall into a tin can. The union of the two
slivers contributes to the uniformity, since the irregular thicknesses
are thereby compensated. The diameter of the roller _c_, is equal to
that of each of the cylinders _f_, _f_¹, _f_², _f_³; and the whole five
move with equal velocity. The same correspondence exists between the
rollers _n_ and _i_. Thus the sliver of flax is not stretched either by
its passage from _e_, upon the heckles, nor between _i_ and _n_, but
solely in passing from the heckles to the rollers _i h_. The heckle
teeth of this machine do not stand perpendicularly, but are bent
somewhat backwards; so as to retain the flax more firmly. The revolving
cylindrical brush _o_, is placed over and a little in front of the
pressing roller _h_, in order to take off all the filaments of flax
adhering to their circumference, and to toss them onwards where they may
again unite with the slivers. For the sake of perspicuity, the rollers
_h_, and those brushes are left out in _fig._ 440., but the latter are
particularly shown in _fig._ 442., while a portion of their axis _q_, is
however shown in _fig._ 440. The pressure of the cylinder _h_, upon the
cylinder _i_, is produced by the weight _r_, _fig._ 439., which hangs
upon the lever _s_; the lever pulls down at _t_, a vertical rod, whose
upper hook-shaped end embraces the axis of _h_ in the middle of its
length.

[Illustration: 442]

_Second principal operation; the formation of rovings._--Mr.
Wordsworth’s improvements in machinery for preparing, drawing, and
roving flax, hemp, wool, and other fibrous substances, consists in a
novel contrivance or mechanism to be adapted to the machine commonly
called the gill, employed for preparing, drawing, and roving flax and
hemp, and for combing and spinning long wool; which improvements allow
the points of the travelling heckles to continue longer in operation
than in the ordinary construction of gill, and cause the heckle points
to be withdrawn from the fibres at the end of the stroke without the
possibility of their drawing the fibres down with them.

[Illustration: 443]

[Illustration: 444]

[Illustration: 445]

The manner of effecting this object will be seen by reference to the
several figures which exhibit a gill on this improved plan in different
views. _Fig._ 443. is a plan or horizontal view, exhibiting the upper
surface of the machine; and _fig._ 444. is a longitudinal section taken
through the middle of the machine: _fig._ 445. is a representation of
the front of the machine, but in which several parts have been removed
to show the action of the heckles more perfectly.

[Illustration: 446 447 448 449 450 451 452 453]

The several heckles _a a a_ are formed by a series of needles or heckle
points set into a metal bar, as represented on an enlarged scale in
_figs._ 446. and 447. These bars are each of them suspended in a frame
or carriage _b b b_ (shown in two views at _figs._ 448. and 449.), by
means of double jointed levers _c c_, seen in two positions, at _figs._
450. and 451.; the heckle bar, its levers and carriage or frame, being
shown put together in _figs._ 452. and 453.

When the heckles are in operation, the points are raised, as in _fig._
452.; but when they are withdrawn from the fibres, then the points are
sunk down into the carrying frames, as _fig._ 453.

These two positions of the heckles are produced by the knobs or parts
_d_, that project from the jointed levers _c_, acting against the edges
of guide bars, which will be explained in describing the operations of
the machine.

The several heckles are adapted and made to work in the machine by
attaching the ends of the respective frames or carriages _b_, to
travelling endless chains _e e_, seen in _figs._ 443., 444., and 445.
These endless chains pass over fluted guide rollers _f f_, seen best in
_figs._ 444. and 445., and over horizontal bars _g g_, seen best in
_figs._ 443. and 444. The chains with the heckles are driven through the
machine by rotatory spur wheels _h h_; see _figs._ 443. and 444., the
teeth of which take into the spaces between the cylindrical parts of the
several heckle carriages _b b_, and consequently drive the heckles
forward; and these spur wheels are actuated by a train of toothed geer
from the first driving shaft _i_, which gives motion to all the
operative parts of the machine.

If flax, hemp, long wool, or other fibrous material, be passed into the
machine at the back part by a feeding cloth or creeper through a guide
_k_, best seen in _figs._ 443. and 444., and be conducted under and over
the feeding rollers _l_, _m_, and _n_, and over the heckles _a a a_ to
the drawing rollers _o_ and _p_, and thence to the flyer and bobbin, or
to a receiving can, the fibres will be opened in their progress, and
combed by the points of the heckles entering into and separating the
fibres, the material being drawn by a different speed to that with which
the heckles travel.

This operation of preparing, drawing, and roving flax and hemp, and the
general construction of a machine of this kind being well understood, it
is not necessary to explain its details, excepting as respects those
parts which constitute the present improvements.

It will be perceived, by reference to _figs._ 443. and 444., that the
knobs _d_, which project from the jointed levers _c_, as they travel
along the machine, bear against the outer edges of the two fixed guide
bars _q q_ that extend along the top of the machine above the heckles,
which keep the heckle points raised, as in _fig._ 451. This will also be
very evidently seen in the front view of the machine, _fig._ 445., where
the upper heckle bar _a_ is raised in its carriage _b_, by the knobs _d
d_ bearing against the outer edges of these guide bars _q q_. But when
the endless chains _e e_, which support and conduct the frames or
carriages of the heckles, have advanced the heckle points to within a
very little distance of the drawing rollers (see _fig._ 444.) then the
knob _d_ of the jointed levers at each end of the heckle bar passes the
ends of the guide bars _q q_, and they immediately come in contact with
two inclined planes _r r_, seen in _figs._ 443. and 444., which
instantly depress the levers _c_, and consequently cause the heckle bar
_a_, with its points to descend in the frame or carriage _b_,
withdrawing the points from the fibres of the material almost in a
perpendicular direction.

The heckles that have become thus depressed pass with their carriages by
the traversing of the endless chains along the under part of the
machine, and when they arrive at the back, and begin to rise, the guide
bars _q q_, being at their commencement slightly bent, conduct the knobs
_b_ of the levers _c_ until they are forced back into the positions
first described, whereby the heckle points are raised, as they come to
the upper part of the machine, into effective operation. The fibres of
material operated upon, after passing through the drawing process
between the rollers, may be roved, twisted, or spun, by the employment
of a bobbin and flyer, as shown in _fig._ 444., or may be delivered into
a can, to be roved, twisted, or spun, by other machinery, by
substituting a pair of conducting rollers instead of the bobbin and
flyer, which shall conduct the sliver of material into a tin can below.

The descent of the heckles _a_, into their frames _b_, by the falling of
the levers _c_, _c_, precludes the possibility of the fibres of the
material operated upon being carried down under the machine by the
points, as frequently happens in gill machines of the ordinary
construction; and this mode of mounting the heckles and traversing them
with the assistance of the guide bars _q_, _q_, and inclined planes _r_,
_r_, allows the heckle points to be brought much nearer to the drawing
rollers _o_, _p_, by means of the metal bars in which the heckle points
or needles are set, falling below the centre of the endless chain _e_,
_e_, as shown in _figs._ 443. and 444., and thereby affords the means of
preparing, drawing, and roving various qualities of flax, hemp, wool and
other fibrous materials, particularly such as have a much shorter staple
than any fibrous materials hitherto operated upon in gill machinery.

Another most ingenious and effective improvement made of late years in
the flax spinning machinery, is that patented by Messrs. Westley and
Lawson, in August 1833, and since then introduced into practice with
great advantage. It applies to the _gill_ or mechanism employed for
opening, straightening, and separating the fibres of flax, hemp, and
long wool in the operation of slivering. The peculiar feature here is a
method of driving the heckle bars through the gill machine by means of
perpetual screws or worm shafts, instead of by chains and spur wheels,
as in the former constructions.

The heckle bars which lie across the machine, are, by the present
patentees, supported at their ends by fixed horizontal guide rails, on
which they slide, while the extremities of the heckle bars are inserted
in the helical grooves of the worm shafts, which are placed in
horizontal positions at the sides of the machine; and hence the rotatory
motions given to these screw shafts, cause the heckle bars to be driven
along the guide rails with an uniform simultaneous movement.

The heckle bars having performed their usual office, that is, having
combed and separated the fibres of the material as they move onward, are
at the front part of the machine depressed and put out of operation by
means of rotatory cams; and by the assistance of guide levers, each
heckle bar, when it arrives at the end of the upper horizontal guide
rail, is conducted down to the lower horizontal guide rails, where the
extremities of the comb-bars falling into the helical grooves of a lower
pair of worm shafts, revolving in an opposite direction to the former,
thereby give the heckle bars a retrograde movement. When they arrive at
the back end of their horizontal guide rails, they are, by similar
rotatory cams, raised again to the upper horizontal guide rails, which
coming into geer with the upper worm shafts, are moved onwards as at
first.

By this means a succession of heckles is continually advancing upon the
upper guide rails, having their points in constant operation between the
fibres of the textile materials, while their vertical position is
secured during their whole course.

[Illustration: 454]

[Illustration: 455]

[Illustration: 456]

_Fig._ 454. is a horizontal representation of a gill machine, shewing
the present improvements; but some of the upper portions of the machine
are removed, to let the working parts be seen more clearly. _Fig._ 455.
is a side view of the gill; and _fig._ 456. a vertical section taken
longitudinally. The driving rigger or pulley _a_, is fixed upon the
front roller _b_, commonly called the drawing roller, because when
pressed upon by the upper wooden roller _c_, it draws out the fibres
between them. The rollers _d_, _e_, _f_, are the ordinary back or
holding rollers, for retaining the fibres, while they suffer powerful
traction by the rollers _b_, _c_, over the needles or points of the
heckle bars. The upper guide rail above mentioned, upon which the heckle
bars slide, is shown at _g_, in _fig._ 456., and the lower guide rail at
_h_; the series of heckle bars with their needles are represented at
_i_, _i_, _i_, _i_, _i_, _i_; the upper worm shafts _k_, _k_, are
mounted in brackets made fast to the sides of the frame; a similar pair
of worm shafts _l_, being mounted in like manner below. These worm
shafts _k_ and _l_, on each side are connected together by toothed
wheels _m_, and upon the axles of the lower worm shafts, bevelled
pinions _n_ are fixed, which take into corresponding bevel pinions on
the transverse shaft or axle _o_. This shaft _o_, being connected by a
train of toothed wheel work with the axle of the drawing roller _b_, as
shown in _figs._ 454. and 455., the rotation of the roller _b_, causes
the shaft _o_ to turn also, and the bevel geer _n_ and _o_, produce the
rotatory motion of the worm shafts _k_ and _l_, which turn in contrary
directions.

It will be seen, from _fig._ 454., that the ends of the heckle bars _i_,
have nibs or projections which fall into the grooves of the screw or
worm shaft, and that being supported below, upon their guide rails, as
the worm-shafts _k k_ revolve, the upper range of heckle bars will be
progressively advanced towards the front part of the machine. By
referring to _fig._ 456. it will be perceived, that as each heckle bar
arrives at the front end of the guide rail _g_, a finger _p_, called a
tappet or cam, on the shaft _k_, strikes it down to the lower guide
rails _h_; and, in order that its descent may be truly vertical,
weighted levers _q q_, in front, are made to press against the face of
the heckle bar as it descends. This bar having now arrived at the lower
guide rails _h_, lets fall its nibs into the grooves of the lower worm
shafts _l_, by whose rotation the heckle bar is made to retrograde, or
return towards the back of the machine. When the heckle bar has reached
the hinder end of the guide rail _h_, a finger or tappet, _r_, on the
lower worm shaft, comes under it and raises the heckle bar, guided by
the back-weighted levers _s_, as shown in _fig._ 456., till it is
elevated to the level of the upper guide rail _g_; when the threads of
the upper worm-shafts take hold of its nibs as before, and conduct it
forward upon the guide rail in the way already described. Thus the
continued rotation of the worm shafts _k k_, and _l l_, causes the whole
series of heckle bars to travel along the guide rails, and the tappets
_p_ and _r_, by alternately depressing and raising them at the ends of
the said rails, cause them to move in a regular circuit, yet so as to
preserve their verticality.

The claim made under this patent is, for every mode in which screw or
worm shafts may be adapted to conduct the bars carrying the needles or
heckle-teeth through a machine for preparing, drawing, or roving textile
fibres.

In December 1835, Messrs. Hope and Dewhurst obtained a patent for
improvements in the manufacture of flax, which deserve notice. These are
of both a chemical and mechanical nature. The first consists in steeping
the flax in dilute sulphuric acid, of a certain strength, and for a
certain time, proportioned to the quality of the fibres, the coarser
requiring the stronger application. By this means the gummy matter and
the outer shell will be loosened and easily detached. It is then to be
passed between squeezing rollers, afterwards well washed, boiled in a
solution of soap and water for a few hours, and finally passed again
through the rollers. These processes may be repeated till the flax
acquires the desired glossiness and separation of fibres. It is next to
be beaten, and passed once or twice over an ordinary heckle or stiff
brush.

[Illustration: 457 458 459 460 461]

The second part, or the mechanical, is represented by the figures 457.,
458., 459., 460., and 461. _Fig._ 457. is a sectional elevation in part
of the construction of the spindle, bobbin and flyer proposed for
spinning all kinds of flax or hemp. _Fig._ 458. answers for spinning
coarser yarns; _fig._ 459. shows how yarns are to be spun for weft, and
wound upon what is called a “pin cop bobbin.”

_a a a_ is the stationary or fixed spindle of the ordinary throstle
frame, which is surrounded by the tube _b b_, and connected to the
wharve or pulley _c_, by which the flyer _d_ is driven. The flyer is
furnished with guides or conductors _e e_, which lead the yarn
immediately to the bobbin; this flyer is also provided with a small
central shaft which supports it, and runs in the small cup or recess at
the top of the stationary spindle _a_, and is fixed with the flyer to
the tube _b b_, which is altogether carried round or driven by the
wharve _c_.

It will be seen by _fig._ 460., that the wharve _c_, and tube _b_, are
connected at bottom by a half-lap coupling joint or clutch; this is for
the purpose of allowing the tube _b_ to be slidden up the spindle, and
more readily removing the bobbin when it is full of yarn, without
stopping the frame, or removing the band from the wharve _c_, the tube
of which runs in the step or cup _h_, fixed upon the bolster rail near
the bottom of the throstle frame. The traversing of the bobbin or the
copping motion is effected exactly in the same manner as in ordinary
throstles, that is, by the lifting and lowering of the copping rail _i_,
which in this instance supports the bobbin. In _fig._ 458. the flyer is
constructed of twice the length of the bobbin, to allow this to rise and
fall freely within it, and is connected at top by a slight cross piece,
for the purpose of preventing the arms of the flyer from expanding by
the centrifugal force, when turning with great velocity. The flyer for
spinning coarse numbers requires to have an inner tube _k_, to support
the spindle. The bobbins are supported upon a washer _l_, _l_. The
spindle is allowed to revolve in a slight degree by the friction of the
drag-weight _m_, _m_. This weight has a hole formed in it with a flat
side, as shown in _fig._ 461.

Flax has been for a long period spun wet in the mills; a method no doubt
copied from the practice of housewives moistening their yarn with their
saliva at the domestic wheel. Within a few years the important
improvement has been introduced, of substituting hot for cold water, in
the troughs through which the fibres in the act of spinning pass. By
this means a much finer, smoother, and more uniform thread can be spun
than in the old way. The flax formerly spun to twelve pounds a bundle,
is, with hot water, spun to six. The inconvenience of the spray thrown
from the yarn on the flyers remains; aggravated by increased heat and
dampness of the room, where this hot process goes on. Being a new
expedient, it receives daily changes and ameliorations. When first
employed, the troughs of hot water were quite open; they are now
usually covered in, so as almost entirely to obviate the objections to
which they were previously liable. With the covers has been also
introduced a new method of piecening or joining on any end, which may
have been run down, namely, by splicing it to the adjoining roving,
whereby it is carried through the water without imposing a necessity on
the spinner to put her hand into the water at all. In some places she
uses a wire, for the purpose of drawing through the end of the roving to
mend a broken yarn.

This may be considered the inherent evil of flax-spinning,--the spray
thrown off by the wet yarn, as it whirls about with the flyer of the
spindles. A working dress, indeed, is generally worn by the spinners;
but, unless it be made of stuff impermeable to water, like Macintosh’s
cloth, it will soon become uncomfortable, and cause injury to health by
keeping the body continually in a hot bath. In some mills, water-proof
cloth and leather aprons have actually been introduced, which are the
only practicable remedy; for the free space which must be left round the
spindles for the spinner to see them play, is incompatible with any kind
of fixed guard or _parapluie_.

There was before the late Factory Bill passed, a class of very young
children employed in the flax mills, under the name of little doffers,
forming generally a troop of from four to ten in each spinning-room,
who, the moment they perceived the bobbins of any frame or side of a
frame exhausted of roving, ran together, and furnished it with full ones
as quickly as possible. They were not numerous in all, but they had an
occupation requiring a great activity and attention. It was practised
also in the fine spinning-rooms, which are perfectly free from dust;
and, as it involved a kneeling and stooping position, seemed peculiarly
appropriate to children, and is still done by them at a somewhat more
advanced age.

[Illustration: 462]

The adjoining _fig._ 462. will serve to explain the mechanism by which
the fine spinning of flax is performed. The front pair of drawing
rollers represented at F, was at one time moistened by letting water
trickle upon it, from a vessel B, furnished with a stopcock placed a
little above, or by immersing one half of the under-roller in the
water-trough as at A. The roller pair C, which receives the fine rovings
from bobbins placed on skewers or upright pins in the creel behind, is
so mounted as to be fixed at any desired distance from the front rollers
F. This distance should be always a little more than the average length
of the filaments of the line; for if it were equal to it, they would be
seized at both ends by the two pairs of rollers, which move with
different velocities, and would be torn asunder, instead of being drawn
out alongside of each other. The front rollers indeed move in many such
machines four times faster than the back pair. The rest of this
flax-spinning apparatus resembles in every respect the throstle frame of
the cotton-spinner. The thread, as it escapes from the front rollers,
gets twisted by the spindle and flyer, and wound up in constant
progression on the bobbin, the motion of the latter being retarded
either by a washer of leather beneath its lower end, or sometimes, as
shown in the figure, by a weighted lever H, suspended from a cord, which
embraces the pulley-groove turned on the lower end of the bobbin. This
friction of this cord on the pulley, which may be varied by changing the
length of leverage at which the weight acts, gives the bobbin the
requisite retardation for winding up the yarn.

The bobbin G, at the same time that it has this retarded movement of
revolution on its axis, has another motion up and down on the spindle I,
to present itself at different points to the thread, and to cause the
equal distribution of this over the surface of the bobbin-barrel. This
latter motion is given by a double eccentric L, which by turning slowly
on its axis, makes the balance-lever M oscillate, and thereby raises or
depresses the bobbin-rail with its row of spindles. N is a section of
the long tin drum, which extends the whole breadth of the frame, and
communicates its rotatory motion, derived from the steam-pulley, to the
spindles, by the intervention of the endless cotton cords O, as also to
the fluted rollers C, F, and to the axis of the heart-shaped or
eccentric wheel L, working in an endless screw.

The ratio of the velocity of the rollers of supply C, with the front or
delivering rollers F, and with the spindles, is proportional to the
fineness of the yarn. For low numbers, the draught is usually fourfold.
The speed of the spindles also varies with the quality of the yarn,
according as it is intended for warp or weft; the former requiring more
twist than the latter; but never so much as to cause it to snarl into a
knot, when left free to turn on itself.

One of the most important improvements hitherto made in the spinning of
flax is that for which James Kay, of Preston, obtained a patent in July,
1825. Its peculiar feature is the maceration in warm water of the
slivers or rovings, previously to spinning them, by conducting them into
tin cans, with open bottoms, fitted into circular boxes having holes
like a cullender, and immersed into a trough of warm water. The slivers
as they pass from the rollers are let fall through the cans into these
boxes, when they are to be repeatedly pressed and beaten down by a
plunger, or the action of rollers, as may be most convenient. The
material must be thoroughly freed from air, and macerated. After five or
six hours it is to be removed from the water, and placed in its
compressed state at the back part of a drawing and spinning machine. The
cake being now turned over, the end of the roving first deposited in the
can is drawn out with care, then raised up, and passed over a tension
roller to the drawing apparatus. The first pair of rollers for the
drawing process merely retains the filaments; while at a distance of two
inches and a half the drawing rollers are placed. Both are fluted for
the purpose of taking firm hold of the material; and the drawing pair is
made to move eight times quicker than the retaining. As the flax fibres
have in this state little or no elasticity, and as they adhere loosely
in their macerated condition, the drawing rollers must be placed thus
close to the retaining rollers, and being made to move at a proper
speed, produce an extremely attenuated thread.

The adjoining table represents, in three compartments, the most
important rooms in a flax-mill, viz.:--

I. The tow preparing room.

II. The line preparing room for the long flax.

III. One room of spinning machines as a pattern for the rest.

[Illustration: 463 TOW PREPARING ROOM.]

A, lap machine; B, 4-feet breaker card; C, 3 feet 6 inches ditto; D,
3-feet finisher card, 3 workers; E, cut tow, second drawing, 5 heads; F,
cut tow, first drawing, 4 heads; G, cut tow, reg. roving, 32 spindles;
H, 4-feet breaker card; I, 4-feet finisher ditto; K, long tow, first
drawing, 3 heads; L, long tow, second drawing, 4 heads; M, long tow,
roving 4 spindles.

[Illustration: 464 LINE PREPARING ROOM.]

A, cut line, first drawing; B, cut line, second drawing, 4 heads; C, cut
line, third drawing, 5 heads; D, cut line, reg. roving 32 spindles each;
E, long line, first drawing; F, long line, second drawing, 3 heads each;
G, long line, third drawing, 4 heads each; H, long line, roving 16
spindles.

[Illustration: 465 SPINNING ROOM.]

  I.   The line preparing room comprehends:--
       1. Heckling machines with heckles.
       2. Line spreaders, or first drawing slivers.
       3. Frames for the second drawing, of 3 heads each.
       4. Frames for the third drawing, of 4 heads each.
       5. Roving frames of 16 spindles each.
       6. Spare fallers for first drawing with gills.
       7. Ditto ditto for second and third drawing with ditto.
       8. Ditto ditto for roving.

  II.  The cut flax line preparing room:--
       1. Sets of heckling frames (excentric.)
       2. Cutting or breaking machine.
       3. Line spreaders or drawing ditto.
       4. Frames for second drawing, 4 heads each.
       5. Ditto      third ditto,    5 ditto.
       6. Ditto, regulator roving, 32 spindles each.
       7. Spare fallers with gills for first drawing.
       8. Ditto, ditto             for second and third ditto.
       9. Ditto, ditto, with gills for roving.

  III. Long or uncut flax tow preparation:--
       1. Lap machine.
       2. Breaker cards, 4 feet diameter.
       3. Finisher ditto, ditto.
       4. Frames for first drawing, 3 heads each.
       5. Ditto for second drawing, 3 heads each.
       6. Ditto for roving, 16 spindles each.
       7. Spare fallers, with gills for first and second drawing.
       8. Ditto, ditto, ditto,  for roving.

  IV.  Cut flax tow preparation:--
       1. Lap machine.
       2. First breaker cards, 4 feet diameter.
       3. Second ditto, ditto, 3 feet 6 inches ditto.
       4. Finisher cards with 8 workers.
       5. First drawing frames, of 4 heads each.
       6. Second ditto, ditto, of 5 ditto.
       7. Frames for regulator roving, 32 spindles each frame.
       8. Spare fallers with gills for first and second drawing.
       9. Ditto, ditto,            for roving.

  V.   Spinning rooms for both lines and tows:--spindles in frames in a
       number proportional to the number of the above preparation
       machines; and consequently to     the quantity and quality of the
       flax yarn intended to be spun.

  VI.  Utensils and tools; such as cards clothing with needle pointed
       filleting.

Observations upon the above statement of the series of machinery
requisite in a modern flax mill of the most improved construction:--

The long or uncut flax to be spun into yarns averaging 30 leas per lb.

Each heckling machine will produce about 4-1/2 cwts. per day, which
would be distributed into 200 lbs. of line, and 266-2/3 of tow.

The total with 3 machines would be therefore 600 lbs. of line, and 800
lbs. of tow.

The preceding statement contains three systems of line preparing, each
system being composed of--

  1 line spreader, or first drawing;
  1st frame of 3 heads; 2d ditto, 2 slivers each;
  1 ditto of   4 ditto; 3d ditto, ditto ditto;
  2 ditto rovings of 32 spindles, which are capable of supplying about
    640 spinning ditto;
  1 line spreader being allowed for contingencies.

The above statement contains 3 systems of tow (uncut) preparation, each
system being composed of--

  1 breaker card;
  2 finisher ditto,
  1 frame of first drawing, 3 heads of 4 slivers each;
  1 ditto    second ditto,  4 ditto,   4 ditto ditto;
  2-1/3 ditto rovings or 37 spindles, which are capable of supplying
    about 660 spinning ditto;
  1 lap machine being sufficient for 2 or 3 systems;
  1 extra finisher is deemed desirable.

The statement contains 2 systems of heckling machines for cut flax, a
system consisting of either 8 or 10 machines; for the coarser work, 8
machines in succession finer and finer, are sufficient; but for the
finest 10 or 12 are required. Each system will produce between 2 and 300
lbs. per diem, of raw flax, heckled, divided on the average into 170
lbs. line, 280 lbs. tow, which will about equal the supply of the 5th
system contained in the statement, each consisting of--

  1 line spreader or 1st drawing;
  1 frame 2d drawing; 4 heads 4 slivers each;
  1 ditto 3d ditto,   5 ditto 4 ditto ditto;
  1 ditto roving 32 spindles;
    and are capable of supplying about 480 ditto, of spinning.

The statement contains 2 systems of tow (cut flax) preparings, each
system being composed of--

  2 second breaker card;
  4 finishers ditto;
  4 frames 1st drawing, 4 heads each 4 slivers;
  4 ditto 2d ditto,     5 ditto ditto, 4 ditto;
  4 regulator rovings 128 spindles,
    and are capable to supply about 1800 spinning ditto.
  1 first-breaker card and lap frame are sufficient to 2 or 3 systems.

Summary view:--

  Long  or uncut line 3 systems of  640 spindles = 1920
  Ditto     --   tow  3 ditto       660 ditto      1980   3900
                                                   ----
  Cut       --   line 5 ditto       480 ditto      2400
  Ditto     --   tow  2 ditto      1800 ditto      3600   6000
                                                   ----   ----
                              Total of spinning spindles  9900

3900 spindles, at an average of 30 leas yarn per lb., would turn off 9
leas per spindle per diem with waste circa 1400 lbs.

6000 spindles, at an average of 100 leas yarn per lb., would turn off 6
leas per spindle per diem with waste circa 450 lbs.

  Yarns produced:                                           _£.  s. d._
  Of average 30 leas per lb. per week circa 1050 boles at
                                                     9_s._  472  10  0
  Of ditto  100 ditto --     --             1080 --         486   0  0
                                            ----            ----------
                       Total weekly produce 2130            958  10  0

                             _£. s. d._
  Weekly charges, wages, &c. 150  0  0
  Flax                       400  0  0
  Weekly expenses             40  0  0
  Interest on 60,000_l._ }   120  0  0
  10 per annum           }                                  710   0  0
                              ---------                     ----------
                                             Weekly profit  248  10  0

Measures of flax yarn; and statistics of the linen trade for the United
Kingdom.

  One lea of flax yarn at Leeds is = 300 yards.
  One spindle Scotch               =  38 leas  = 11400 yards.
  One rand                         =   6 ditto =  1800 ditto.
  One dozen is 12 rands            =  72 ditto = 21600 ditto.

When yarn is estimated in Nos. it implies the number of leas in one
pound weight; as in cotton, it means the number of hanks of 840 yards
each in one pound.

_Imports of flax and tow, or codilla of hemp and flax, at a duty of 1d.
per cwt., in_

                          1834.      1835.       1837.        1838.
                         -------    -------    ---------    ---------
                           lbs.       lbs.        lbs.         lbs.
                         811,722    740,814    1,529,116    1,002,256

  _Retained for
  consumption._          794,272    728,143    1,532,059    1,002,408

  Linen yarn exported             2,611,215

  Linen manufactures exported,
  including flax yarn, declared
  value                        _£_3,208,139 _£_3,645,097 _£_2,613,293


FLINT. (_Pierre à fusil_, Fr; _Feuerstein_, Germ.) The fracture of this
fossil is perfectly conchoidal, sometimes glossy, and sometimes dull on
the surface. It is very hard, but breaks easily, and affords very
sharp-edged splintery fragments; whence it is a stone which strikes most
copious sparks with steel. It is feebly translucid, has so fine and
homogeneous a texture as to bear polishing, but possesses little lustre.
Its colours are very various, but never vivid. The blackish-brown flint
is that usually found in the white chalk. It is nearly black and opaque,
loses its colour in the fire, and becomes grayish-white, and perfectly
opaque. Flints occur almost always in nodules or tubercular concretions
of various and very irregular forms. These nodules, distributed in
strata among the chalk, alongside of one another and almost in contact,
form extensive beds; interrupted, indeed, by a multitude of void spaces,
so as to present, if freed from the earthy matter in which they are
imbedded, a species of network with meshes, very irregular both in form
and dimension.

The nodules of silex, especially those found in the chalk, are not
always homogeneous and solid. Sometimes there is remarked an organic
form towards their centre, as a madrepore or a shell, which seems to
have served as their nucleus; occasionally the centre is hollow, and its
sides are studded over with crystals of quartz, carbonate of iron,
pyrites, concretionary silex or calcedony, filled with pulverulent
silica nearly pure, or silex mixed with sulphur; a very singular
circumstance.

Flints are observed to be generally humid when broken immediately after
being dug out of the ground; a property which disappears after a short
exposure to the air. When dried they become more brittle and more
splintery, and sometimes their surfaces get covered at old fractures
with a thin film or crust of opaque silex.

Flints calcined and ground to a powder enter into the composition of all
sorts of fine pottery ware.

The next important application of this siliceous substance is in the
formation of gun-flints, for which purpose it must be cut in a peculiar
manner. The following characters distinguish good flint nodules from
such as are less fit for being manufactured. The best are somewhat
convex, approaching to globular; those which are very irregular,
knobbed, branched and tuberose, are generally full of imperfections.
Good nodules seldom weigh more than 20 pounds; when less than 2, they
are not worth the working. They should have a greasy lustre, and be
particularly smooth and fine grained. The colour may vary from
honey-yellow to blackish-brown, but it should be uniform throughout the
lump, and the translucency should be so great as to render letters
legible through a slice about one-fiftieth of an inch thick, laid down
upon the paper. The fracture should be perfectly smooth, uniform, and
slightly conchoidal; the last property being essential to the cutting
out of perfect gun-flints.

Four tools are employed by the gun-flint makers.

First, a hammer or mace of iron with a square head, from 1 to 2 pounds
weight, with a handle 7 or 8 inches long. This tool is not made of
steel, because so hard a metal would render the strokes too harsh, or
dry as the workmen say, and would shatter the nodules irregularly,
instead of cutting them with a clean conchoidal fracture.

Second, a hammer with 2 points, made of good steel well hardened, and
weighing from 10 to 16 ounces, with a handle 7 inches long passing
through it in such a way that the points of the hammer are nearer the
hand of the workman than the centre of gravity of the mass.

Third, the disc hammer or roller, a small solid wheel, or flat segment
of a cylinder, parallel to its base, only two inches and a third in
diameter, and not more than 12 ounces in weight. It is formed of steel
not hardened, and is fixed upon a handle 6 inches long, which passes
through a square hole in its centre.

Fourth, a chisel tapering and bevelled at both extremities, 7 or 8
inches long, and 2 inches broad, made of steel not hardened; this is set
on a block of wood, which serves also for a bench to the workmen. To
these 4 tools a file must be added, for the purpose of restoring the
edge of the chisel from time to time.

After selecting a good mass of flint, the workman executes the following
four operations on it.

1. _He breaks the block._ Being seated upon the ground, he places the
nodule of flint on his left thigh, and applies slight strokes with the
square hammer to divide it into smaller pieces of about a pound and a
half each, with broad surfaces and almost even fractures. The blows
should be moderate, lest the lump crack and split in the wrong
direction.

2. _He cleaves or chips the flint._ The principal point is to split the
flint well, or to chip off scales of the length, thickness, and shape
adapted for the subsequent formation of gun flints. Here the greatest
dexterity and steadiness of manipulation are necessary; but the fracture
of the flint is not restricted to any particular direction, for it may
be chipped in all parts with equal facility.

The workman holds the lump of flint in his left hand, and strikes with
the pointed hammer upon the edges of the great planes produced by the
first breaking, whereby the white coating of the flint is removed in
small scales, and the interior body of the flint is laid bare; after
which he continues to detach similar scaly portions from the clean mass.

These scaly portions are nearly an inch and a half broad, two inches and
a half long, and about one-sixth of an inch thick in the middle. They
are slightly convex below, and consequently leave in the part of the
lump from which they were separated a space slightly concave,
longitudinally bordered by two somewhat projecting straight lines or
ridges. The ridges produced by the separation of the first scales must
naturally constitute nearly the middle of the subsequent pieces; and
such scales alone as have their ridges thus placed in the middle are fit
to be made into gun-flints. In this manner the workman continues to
split or chip the mass of flint in various directions, until the defects
usually found in the interior render it impossible to make the requisite
fractures, or until the piece is too-much reduced to sustain the smart
blows by which the flint is divided.

3. _He fashions the gun-flints._ Five different parts may be
distinguished in a gun-flint. 1. The sloping facet or bevel part, which
is impelled against the hammer of the lock. Its thickness should be from
two to three twelfths of an inch; for if it were thicker it would be too
liable to break; and if more obtuse, the scintillations would be less
vivid. 2. The sides, or lateral edges, which are always somewhat
irregular. 3. The back or thick part opposite the tapering edge. 4. The
under surface, which is smooth and rather concave. And 5. The upper
face, which has a small square plane between the tapering edge and the
back, for entering into the upper claw of the cock.

In order to fashion the flint, those scales are selected which have at
least one of the above mentioned longitudinal ridges; the workman fixes
on one of the two tapering borders to form the striking edge, after
which the two sides of the stone that are to form the lateral edges, as
well as the part that is to form the back, are successively placed on
the edge of the chisel in such a manner that the convex surface of the
flint, which rests on the forefinger of the left hand, is turned towards
that tool. Then with the disc hammer he applies some slight strokes to
the flint just opposite the edge of the chisel underneath, and thereby
breaks it exactly along the edge of the chisel.

4. The finishing operation is the _trimming_, or the process of giving
the flint a smooth and equal edge; this is done by turning up the stone
and placing the edge of its tapering end upon the chisel, in which
position it is completed by 5 or 6 slight strokes of the disc hammer.
The whole operation of making a gun-flint, which I have used so many
words to describe, is performed in less than one minute. A good workman
is able to manufacture 1000 good chips or scales in a day (if the
flint-balls be of good quality), or 500 gun-flints. Hence, in the space
of 3 days, he can easily cleave and finish 1000 gun-flints without any
assistance.

A great quantity of refuse matter is left, for scarcely more than half
the scales are good, and nearly half the mass in the best flints is
incapable of being chipped out; so that it seldom happens that the
largest nodules furnish more than 50 gun-flints.

Flints form excellent building materials; because they give a firm hold
to the mortar by their irregularly rough surfaces, and resist, by their
nature, every vicissitude of weather. The counties of Kent, Essex,
Suffolk, and Norfolk contain many substantial specimens of
flint-masonry.


FLOSS, of the puddling furnace, is the fluid glass floating upon the
iron produced by the vitrification of the oxides and earths which are
present.


FLOSS-SILK (_Filoselle_, _Bourre de soie_, or _fleuret_, Fr.); is the
name given to the portions of ravelled silk broken off in the filature
of the cocoons, which is carded like cotton or wool, and spun into a
soft coarse yarn or thread, for making bands, shawls, socks, and other
common silk fabrics. The floss or fleuret, as first obtained, must be
steeped in water, and then subjected to pressure, in order to extract
the gummy matter, which renders it too harsh and short for the spinning
wheel. After being dried it is made still more pliant by working a
little oil into it with the hands. It is now ready to be submitted to
the carding engine. See COTTON MANUFACTURE. It is spun upon the flax
wheel.

The female peasants of Lombardy generally wear clothes of homespun floss
silk. Of late years, by improved processes, pretty fine fabrics of this
material have been produced both in England and France. M. Ajac, of
Lyons, presented at one of the French national exhibitions of the
objects of industry, a great variety of scarfs and square shawls, of
_bourre de sole_, closely resembling those of _cachemere_.


FLOUR; the finely ground meal of wheat, and of any other corns or
_cerealia_. See BREAD.


FLOUR OF WHEAT, _Adulterations of_, _to detect_.

The first method is by specific gravity. If potato flour be added, which
is frequently done in France, since a vessel which contains one pound of
wheat flour will contain one pound and a half of the fecula, the
proportion of this adulteration may be easily estimated. If gypsum or
ground bones be mixed with the flour, they will not only increase its
density still more; but they will remain after burning away the meal.

The second method is by ascertaining the quantity of gluten which the
suspected sample will afford, by the process prescribed under the
article BREAD. The two following chemical criteria may also be employed.

1st. Nitric acid has the property of colouring wheat flour of a fine
orange yellow, whereas it affects the colour neither of fecula nor
starch.

2nd. Pure muriatic acid colours good wheat flour of a deep violet, but
dissolves fecula or starch, and forms with it a light, colourless,
viscous fluid, decomposable by alkalis. It may also be observed, that as
fecula absorbs less water than flour, this affords a ready means of
detection.

The adulteration with bean or pea flour may be detected by pouring
boiling water upon it, which developes the peculiar smell of these two
substances.


FLOWERS (_Fleurs_, Fr.; _Blumen_, Germ.) of benzoin, of sulphur, of
zinc, &c., is the appellation given by the older chemists to such
substances as were obtained in a pulverulent or rather minutely
crystalline form by the process of sublimation.


FLOWERS, ARTIFICIAL, MANUFACTURE OF. The art of representing by flowers,
leaves, plants, &c., vegetable nature in her ornamental productions,
constitutes the business of the artificial florist. The Italians appear
to have been the first people in Europe who excelled in the art of
making artificial flowers; but of late years the French have been most
ingenious in this branch of industry.

Ribbons folded in different forms and of different colours were
originally employed for imitating flowers, by being attached to wire
stems. This imitation soon gave way to that by feathers, which are more
delicate in texture, and more capable of assuming a variety of
flower-like figures. But a great difficulty was encountered in dyeing
them with due vivacity. The savages of South America manufacture perfect
feather flowers, derived from the brilliant plumage of their birds,
which closely resemble the products of vegetation. The blossoms and
leaves are admirable, while the colours never fade.

The Italians employ frequently the cocoons of the silkworm for this
purpose; these take a brilliant dye, preserve their colour, and possess
a transparent velvety appearance, suitable for petals. Of late years,
the French have adopted the finest cambric for making petals, and the
taffeta of Florence for the leaves. M. de Bernardière employs whalebone
in very thin leaves for artificial flowers; and by bleaching and dyeing
them of various hues, he has succeeded in making his imitations of
nature to be very remarkable.

The colouring matters used in flower dyeing are the following:--

For red; carmine dissolved in a solution of salt of tartar.

For blue; indigo dissolved in sulphuric acid, diluted and neutralized in
part by Spanish whitening.

For bright yellow; a solution of turmeric in spirit of wine. Cream of
tartar brightens all these colours.

For violet; archil, and a blue bath.

For lilac; archil.

Some petals are made of velvet, and are coloured merely by the
application of the finger dipped in the dye.


FLUATES, more properly _fluorides_ (Eng. and Fr.; _Flusssäure_, Germ.);
compounds of fluorine and the metals; as fluor spar, for example, which
consists of fluorine and calcium.


FLUOR SPAR. (_Chaux fluatée_, Fr.; _Spath fluor_, Germ.) This mineral
often exhibits a variety of vivid colours. It crystallizes in the cubic
system; with regular octahedral and tetrahedral cleavages; spec. grav.
3·1 to 3·2; scratches calc spar, but is scratched by a steel point;
usually phosphorescent with heat; fusible at the blowpipe into an opaque
bead; acted on by the acids, with disengagement of a vapour which
corrodes glass; its solution affords precipitates with the oxalates, but
not with ammonia. Its constituents are, fluorine, 48·13; calcium, 51·87
in 100.

Fluor spar occurs subordinate to metallic veins; as to those of lead, in
Derbyshire; of tin, in Saxony and Bohemia; but it is found also in
masses or veins, either in crystalline rocks, associated with quartz,
heavy spar, &c., as in Auvergne, Forez, Vosges, Norberg in Sweden;
Norway; Petersburg; near Hall; Gourock, in Scotland, &c.; or among
secondary limestones, slates, and sandstones, in Derbyshire, Cumberland,
Cornwall, and New Jersey. It exists also in the amygdaloids of Scotland,
and in the volcanic products of Monte Somma at Vesuvius. The variously
coloured specimens, called Derbyshire spar, are worked upon the turning
lathe into vases and other ornamental objects.


FLUX, (Eng. and Fr.; _Fluss_, Germ.) signifies any substance capable of
promoting the fusion of earths or metallic ores by heat. White flux is
the residuum of the deflagration in a red hot crucible, of a mixture of
two parts of nitre, and one of cream of tartar. It is in fact merely a
carbonate of potash. Black flux is obtained when equal parts of nitre
and tartar are deflagrated. It owes its colour to the carbonaceous
matter of the tartaric acid, which remains unconsumed; the quantity of
nitre being too small for that purpose. The presence of the charcoal
renders this preparation a convenient flux for reducing calcined or
oxidized ores to the metallic state. Limestone, fluor-spar, borax, and
several earthy or metallic oxides are employed as fluxes in metallurgy.


FLY POWDER; the black coloured powder obtained by the spontaneous
oxidizement of metallic arsenic in the air.


FODDER; is the name of a weight by which lead and some other metals are
sold in this country. It varies in its amount in different parts of the
kingdom; being in Northumberland estimated at 21 cwts., and in other
counties 22, 23 or even more cwts.


FONDUS; is the name given by the French to a particular style of calico
printing resembling the rainbow, in which the colours are graduated or
melted (_fondus_) into one another, as in the prismatic spectrum. See
PAPER HANGINGS, for a description of the process.


FORGE; (Eng. and Fr.; _Feuer_, Germ.) is the name either of the furnace,
where wrought iron is hammered and fashioned with the aid of heat, or
the great workshop where iron is made malleable. The former is called a
smith’s forge, the latter a shingling mill. See IRON.

[Illustration: 466]

_Fig._ 466. represents a portable truck forge of a very commodious
construction. A is the cylindric leather bellows, pressed down by a
helical spring, and worked by means of the handle at B, which moves the
horizontal shaft C, with its two attached semicircular levers and
chains. D, is the pipe which conducts the blast to the nozzle at E. The
hearth may be covered with a thin fire-tile or with cinders. F is a vice
fixed to the strong rectangular frame. This apparatus answers all the
ordinary purposes of a smith’s forge; and is peculiarly adapted to
ships, and to the execution of engineering jobs upon railways, or in the
country. The height is 2 feet 6 inches; the length is 2 feet 9 inches;
the width 2 feet. Weight about 2 cwt.


FORMIATES; are compounds of formic acid, with the salifiable bases. Many
of them are susceptible of crystallization.


FORMIC ACID; (_Acide Formique_, Fr.; _Ameisensäure_, Germ.) exists in
the bodies of wood ants, associated with the malic or acid of apples.
The artificial formation of this animal secretion, is one of the most
remarkable triumphs of modern chemistry. If 10 parts of tartaric acid,
14 of black oxide of manganese, 15 of concentrated sulphuric acid, and
from 20 to 30 of water be mixed and distilled in a retort, formic acid
will be the liquid product; while carbonic acid will be disengaged. It
may also be generated from other mixtures. This acid is transparent and
colourless, of a pungent sour smell, a strongly acid taste, of specific
gravity 1·1168 at 60° F., and may be re-distilled without suffering any
change. It contains in its most concentrated form 19-3/4 per cent. of
water. The dry acid, as it exists in the _formiates_, is composed of
32·54 carbon, 2·68 hydrogen, and 64·78 oxygen; or of two volumes
carbonic oxide gas, and one volume of vapour of water. It reduces the
oxides of mercury and silver to the metallic state. It has not hitherto
been applied to any use in the arts.


FORMULÆ, CHEMICAL, are symbols representing the different substances,
simple and compound.

  +-------------------------+--------------------+---------+--------+
  |         Name.           |      Formula.      |  Oxygen |Hydrogen|
  |                         |                    |  = 100. |  = 1.  |
  +-------------------------+--------------------+---------+--------+
  |Oxygen                   |O                   | 100·000 | 16·026 |
  |Hydrogen                 |H                   |   6·2398|  1·000 |
  |                         |2H                  |  12·4796|  2·000 |
  |Nitrogen                 |N                   |  88·518 | 14·186 |
  |                         |2N                  | 177·086 | 28·372 |
  |Phosphorus               |P                   | 196·155 | 31·436 |
  |                         |2P                  | 392·310 | 68·872 |
  |Chlorine                 |Cl                  | 221·325 | 35·470 |
  |                         |2Cl                 | 442·650 | 70·940 |
  |Iodine                   |I                   | 768·781 |123·206 |
  |                         |2I                  |1537·562 |246·412 |
  |Carbon                   |C                   |  76·437 | 12·250 |
  |                         |2C                  | 152·875 | 24·500 |
  |Boron                    |B                   | 135·983 | 21·793 |
  |                         |2B                  | 271·966 | 43·586 |
  |Silicon                  |Si                  | 277·478 | 44·469 |
  |Selenium                 |Se                  | 494·582 | 79·263 |
  |Arsenic                  |As                  | 470·042 | 75·329 |
  |                         |2As                 | 940·084 |150·659 |
  |Chromium                 |Cr                  | 351·819 | 56·383 |
  |                         |2Cr                 | 703·638 |112·766 |
  |Molybdenum               |Mo                  | 598·525 | 95·920 |
  |Tungstenium              |Tu or W             |1183·200 |189·621 |
  |Antimony                 |Sb                  | 806·452 |129·243 |
  |                         |2Sb                 |1612·904 |258·486 |
  |Tellurium                |Te                  | 806·452 |129·243 |
  |Tantalum                 |Ta                  |1153·715 |184·896 |
  |                         |2Ta                 |2307·430 |369·792 |
  |Titanium                 |Ti                  | 389·092 | 62·356 |
  |Gold (aurum)             |Au                  |1243·013 |199·207 |
  |                         |2Au                 |2486·026 |398·415 |
  |Platina                  |Pt                  |1215·220 |194·753 |
  |Rhodium                  |R                   | 750·680 |120·305 |
  |                         |2R                  |1501·360 |240·610 |
  |Palladium                |Pd                  | 714·618 |114·526 |
  |Silver (argentum)        |Ag                  |1351·607 |216·611 |
  |Mercury (hydrargyrus)    |Hg                  |1265·822 |202·863 |
  |                         |2Hg                 |2531·645 |405·725 |
  |Copper (cuprum)          |Cu                  | 395·695 | 63·415 |
  |                         |2Cu                 | 791·390 |126·829 |
  |Uranium                  |U                   |2711·360 |434·527 |
  |                         |2U                  |5422·720 |869·154 |
  |Bismuth                  |Bi                  |1330·376 |213·208 |
  |                         |2Bi                 |2660·752 |426·416 |
  |Tin (stannum)            |Sn                  | 735·294 |117·839 |
  |Lead (plumbum)           |Pb                  |1294·498 |207·458 |
  |                         |2Pb                 |2588·996 |414·917 |
  |Cadmium                  |Cd                  | 696·767 |111·665 |
  |Zinc                     |Zn                  | 403·226 | 64·621 |
  |Nickel                   |Ni                  | 369·675 | 59·245 |
  |Cobalt                   |Co                  | 368·991 | 59·135 |
  |                         |2Co                 | 737·982 |118·270 |
  |Iron (ferrum)            |Fe                  | 339·213 | 54·363 |
  |                         |2Fe                 | 678·426 |108·725 |
  |Manganese                |Mn                  | 355·787 | 57·019 |
  |                         |2Mn                 | 711·575 |114·038 |
  |Cerium                   |Ce                  | 574·718 | 92·105 |
  |                         |2Ce                 |1149·436 |184·210 |
  |Zirconium                |Zr                  | 420·238 | 67·348 |
  |                         |2Zr                 | 840·476 |134·696 |
  |Yttrium                  |Y                   | 401·840 | 64·395 |
  |Beryllium (glucinum)     |Be                  | 331·479 | 53·123 |
  |                         |2Be                 | 662·958 |106·247 |
  |Aluminum                 |Al                  | 171·167 | 27·431 |
  |                         |2Al                 | 342·234 | 54·863 |
  |Magnesium                |Mg                  | 158·353 | 25·378 |
  |Calcium                  |Ca                  | 256·019 | 41·030 |
  |Strontium                |Sr                  | 547·285 | 87·709 |
  |Baryum                   |Ba                  | 856·88  |137·325 |
  |Lithium                  |L                   | 127·757 | 20·474 |
  |Natrium (sodium)         |Na                  | 290·897 | 46·620 |
  |                         |2Na                 | 581·794 | 93·239 |
  |Kalium (potassium)       |K                   | 489·916 | 78·515 |
  |Ammonia                  |2N2H³               | 214·474 | 34·372 |
  |Cyanogen                 |2NC                 | 329·911 | 52·872 |
  |Sulphuretted hydrogen    |2HS                 | 213·644 | 34·239 |
  |Hydrochloric acid        |2HCl                | 455·129 | 72·940 |
  |Hydrocyanic acid         |2HNC                | 342·390 | 54·872 |
  |                         |.                   |         |        |
  |Water                    |2H                  | 112·479 | 18·026 |
  |                         |.                   |         |        |
  |Protoxide of nitrogen    |2N                  | 277·036 | 44·398 |
  |                         |.                   |         |        |
  |Deutoxide of nitrogen    |N                   | 188·518 | 30·212 |
  |                         |...                 |         |        |
  |Nitrous acid             |2N                  | 477·036 | 76·449 |
  |                         |.....               |         |        |
  |Nitric acid              | 2N                 | 677·036 |108·503 |
  |                         |.                   |         |        |
  |Hyposulphurous acid      |S                   | 301·165 | 48·265 |
  |                         |..                  |         |        |
  |Sulphurous acid          |S                   | 401·165 | 64·291 |
  |                         |.....               |         |        |
  |Hyposulphuric acid       | 2S                 | 902·330 |144·609 |
  |                         |...                 |         |        |
  |Sulphuric acid           | S                  | 501·165 | 80·317 |
  |                         |.....               |         |        |
  |Phosphoric acid          | 2P                 | 892·310 |143·003 |
  |                         |.....               |         |        |
  |Chloric acid             | 2Cl                | 942·650 |151·071 |
  |                         |......              |         |        |
  |Perchloric acid          | 2Cl                |1042·650 |167·097 |
  |                         |.....               |         |        |
  |Iodic acid               | 2I                 |2037·562 |326·543 |
  |                         |..                  |         |        |
  |Carbonic acid            |C                   | 276·437 | 44·302 |
  |                         |...                 |         |        |
  |Oxalic acid              |2C                  | 452·875 | 72·578 |
  |                         |......              |         |        |
  |Boracic acid             |  2B                | 871·966 |139·743 |
  |                         |...                 |         |        |
  |Silicic acid             |Si                  | 577·478 | 92·548 |
  |                         |..                  |         |        |
  |Selenic acid             |Se                  | 694·582 |111·315 |
  |                         |.....               |         |        |
  |Arsenic acid             | 2As                |1440·084 |230·790 |
  |                         |...                 |         |        |
  |Protoxide of chrome      |2Cr                 |1003·638 |160·840 |
  |                         |...                 |         |        |
  |Chromic acid             |Cr                  | 651·819 |104·462 |
  |                         |...                 |         |        |
  |Molybdic acid            |Mo                  | 898·525 |143·999 |
  |                         |...                 |         |        |
  |Tungstic, or wolfram acid| W                  |1483·200 |237·700 |
  |                         |...                 |         |        |
  |Oxide of antimony        |2Sb                 |1912·904 |306·565 |
  |                         |..                  |         |        |
  |Antimonious acid         |Sb                  |1006·452 |161·296 |
  |                         |....                |         |        |
  |                         |2Sb                 |2012·904 |322·591 |
  |                         |.....               |         |        |
  |Antimonic acid           |2Sb                 |2112·904 |338·617 |
  |                         |..                  |         |        |
  |Oxide of tellurium       |Te                  |1006·452 |161·296 |
  |                         |...                 |         |        |
  |Tantalic acid            |2Ta                 |2607·430 |417·871 |
  |                         |..                  |         |        |
  |Titanic acid             |Ti                  | 589·092 | 94·409 |
  |                         | .                  |         |        |
  |Protoxide of gold        |2Au                 |2586·026 |414·441 |
  |                         |...                 |         |        |
  |Peroxide of gold         |2Au                 |2786·026 |446·493 |
  |                         |..                  |         |        |
  |Oxide of platina         |Pt                  |1415·220 |226·086 |
  |                         |...                 |         |        |
  |Oxide of rhodium         |2R                  |1801·360 |228·689 |
  |                         |.                   |         |        |
  |Oxide of palladium       |Pd                  | 814·618 |130·552 |
  |                         |.                   |         |        |
  |Oxide of silver          |Ag                  |1451·607 |232·637 |
  |                         | .                  |         |        |
  |Protoxide of mercury     |2Hg                 |2631·645 |421·752 |
  |                         |.                   |         |        |
  |Peroxide of mercury      |Hg                  |1365·822 |218·889 |
  |                         | .                  |         |        |
  |Protoxide of copper      |2Cu                 | 801·390 |142·856 |
  |                         |.                   |         |        |
  |Peroxide of copper       |Cu                  | 495·695 | 79·441 |
  |                         |.                   |         |        |
  |Protoxide of uranium     |U                   |2811·360 |450·553 |
  |                         |...                 |         |        |
  |Peroxide of uranium      |2U                  |5722·720 |917·132 |
  |                         |...                 |         |        |
  |Oxide of bismuth         |2Bi                 |2960·752 |474·49  |
  |                         |.                   |         |        |
  |Protoxide of tin         |Sn                  | 835·294 |133·866 |
  |                         |..                  |         |        |
  |Peroxide of tin          |Sn                  | 935·294 |149·892 |
  |                         |.                   |         |        |
  |Oxide of lead            |Pb                  |1394·498 |223·484 |
  |                         |...                 |         |        |
  |Minium                   |2Pb                 |2888·996 |462·995 |
  |                         |..                  |         |        |
  |Brown oxide of lead      |Pb                  |1494·498 |239·511 |
  |                         |.                   |         |        |
  |Oxide of cadmium         |Cd                  | 796·767 |127·691 |
  |                         |.                   |         |        |
  |Oxide of zinc            |Zn                  | 503·226 | 80·649 |
  |                         |.                   |         |        |
  |Oxide of nickel          |Ni                  | 469·675 | 75·271 |
  |                         |.                   |         |        |
  |Oxide of cobalt          |Co                  | 468·991 | 75·161 |
  |                         |...                 |         |        |
  |Peroxide of cobalt       |2Co                 |1037·982 |166·349 |
  |                         |.                   |         |        |
  |Protoxide of iron        |Fe                  | 439·213 | 70·389 |
  |                         |...                 |         |        |
  |Peroxide of iron         |2Fe                 | 978·426 |156·804 |
  |                         |.                   |         |        |
  |Protoxide of manganese   |Mn                  | 455·787 | 73·045 |
  |                         |...                 |         |        |
  |Oxide of manganese       |2Mn                 |1011·575 |162·117 |
  |                         |..                  |         |        |
  |Peroxide of manganese    |Mn                  | 555·787 | 89·071 |
  |                         |.....               |         |        |
  |Manganesic acid          | 2Mn                |1211·575 |194·169 |
  |                         |.                   |         |        |
  |Protoxide of cerium      |Ce                  | 674·718 |108·132 |
  |                         |...                 |         |        |
  |Oxide of cerium          |2Ce                 |1449·436 |232·289 |
  |                         |...                 |         |        |
  |Zirconia                 |2Zr                 |1140·476 |182·775 |
  |                         |.                   |         |        |
  |Yttria                   |Y                   | 501·840 | 80·425 |
  |                         |...                 |         |        |
  |Glucina, or berryllia    |2Be                 | 962·958 |154·325 |
  |                         |...                 |         |        |
  |Alumina                  |2Al                 | 642·334 |109·942 |
  |                         |.                   |         |        |
  |Magnesia                 |Mg                  | 258·353 | 41·404 |
  |                         |.                   |         |        |
  |Lime                     |Ca                  | 356·019 | 57·056 |
  |                         |.                   |         |        |
  |Strontia                 |Sr                  | 647·285 |103·735 |
  |                         |.                   |         |        |
  |Baryta                   |Ba                  | 956·880 |153·351 |
  |                         |.                   |         |        |
  |Lithia                   |L                   | 227·757 | 36·501 |
  |                         |.                   |         |        |
  |Natron, or soda          |Na                  | 390·897 | 62·646 |
  |                         |...                 |         |        |
  |Peroxide of sodium       |2Na                 | 881·794 |141·318 |
  |                         |.                   |         |        |
  |Kali, or potassa         |K                   | 589·916 | 94·541 |
  |                         |...                 |         |        |
  |Peroxide of potassium    | K                  | 789·916 |126·593 |
  |                         |. ...               |         |        |
  |Sulphate of potassa      |K  S                |1091·081 |174·859 |
  |                         |. ...               |         |        |
  |Protosulphate of iron    |Fe S                | 940·378 |150·706 |
  |                         |...  ...            |         |        |
  |Persulphate of iron      |2Fe S³              |2481·906 |397·754 |
  |Protochloride of iron    |Fe 2Cl              | 781·863 |125·303 |
  |Perchloride of iron      |2Fe 2Cl³            |2006·376 |321·545 |
  |Protochloride of mercury |2Hg 2Cl             |2974·295 |476·666 |
  |Perchloride of mercury   |Hg 2Cl              |1708·472 |273·803 |
  |Ferrocyanide of iron     |Fe2NC + 2K2NC       |2308·778 |370·008 |
  |                         |. ...  ... ...     .|         |        |
  |Alum                     |K  S + 2AlS³ + 24 2H|5936·406 |951·378 |
  |                         |. ...  ...  ...     |         |        |
  |Felspar                  |K Si + 2Al  Si³     |3542·162 |567·673 |
  +-------------------------+--------------------+---------+--------+


FOUNDING _of metals, chiefly of Iron._ The operations of an iron foundry
consist in re-melting the pig-iron of the blast furnaces, and giving it
an endless variety of forms, by casting it in moulds of different kinds,
prepared in appropriate manners. Coke is the only kind of fuel employed
to effect the fusion of the cast iron.

The essential parts of a well-mounted iron foundry, are,

1. Magazines for pig irons of different qualities, which are to be mixed
in certain proportions, for producing castings of peculiar qualities; as
also for coal, coke, sands, clay, powdered charcoal, and cow-hair for
giving tenacity to the loam mouldings.

2. One or more coke ovens.

3. A workshop for preparing the patterns and materials of the moulds. It
should contain small edge millstones for grinding and mixing the loam,
and another mill for grinding coal and charcoal.

4. A vast area, called properly the foundry, in which the moulds are
made and filled with the melted metal. These moulds are in general very
heavy, consisting of two parts at least, which must be separated, turned
upside down several times, and replaced very exactly upon one another.
The casting is generally effected by means of large ladles or pots, in
which the melted iron is transported from the cupola, where it is fused.
Hence the foundry ought to be provided with cranes, having jibs movable
in every direction.

5. A stove in which such moulds may be readily introduced, as require to
be entirely deprived of humidity, and where a strong heat may be
uniformly maintained.

6. Both blast and air furnaces, capable of melting speedily the quantity
of cast-iron to be employed each day.

7. A blowing machine to urge the fusion in the furnaces.

_Fig._ 467. represents the general plan of a well-mounted foundry.

_a_, is a cupola furnace of which the section and view will be
afterwards given; it is capable of containing 5 tons of cast-iron.

_a´_, is a similar furnace, but of smaller dimensions, for bringing down
1-3/4 tons.

_a´´_, is a furnace like the first, in reserve for great castings.

_b_, _b_, _b_, _b_, a vast foundry apartment, whose floor to a yard in
depth, is formed of sand and charcoal powder, which have already been
used for castings, and are ready for heaping up into a substratum, or to
be scooped out when depth is wanted for the moulds. There are besides
several cylindrical pits, from five to seven yards in depth, placed near
the furnaces. They are lined with brick work, and are usually left full
of moulding sand. They are emptied in order to receive large moulds,
care being had that their top is always below the orifice from which the
melted metal is tapped.

These moulds, and the ladles full of melted metal are lifted and
transported by the arm of one or more men, when their weight is
moderate; but if it be considerable, they are moved about by cranes
whose vertical shafts are placed at _c_, _d_, _e_, in correspondence, so
that they may upon occasion transfer the load from one to another. Each
crane is composed principally of an upright shaft, embraced at top by a
collet, and turning below upon a pivot in a step; next of a horizontal
beam, stretched out from nearly the top of the former, with an oblique
stay running downwards, like that of a gallows. The horizontal beam
supports a movable carriage, to which the tackle is suspended for
raising the weights. This carriage is made to glide backwards or
forwards along the beam by means of a simple rack and pinion mechanism,
whose long handle descends within reach of the workman’s hand.

[Illustration: 467]

By these arrangements in the play of the three cranes, masses weighing
five tons may be transported and laid down with the greatest precision
upon any point whatever in the interior of the three circles traced upon
_fig._ 467. with the points _c_, _d_, _e_, as centres.

_c_, _d_, _e_, are the steps, upon which the upright shafts of the three
cranes rest and turn. Each shaft is 16 feet high.

_f_, _f_, is the drying stove, having its floor upon a level with that
of the foundry.

_f´_, _f´_, is a supplementary stove for small articles.

_g_, _g_, _g_, are the coaking ovens.

_h_, is the blowing machine or fan.

_i_, is the steam-engine, for driving the fan, the loam-edge stones,

_k_, and the charcoal mill.

_i´´_, are the boiler and the furnace of the engine.

_k´_, workshop for preparing the loam and other materials of moulding.

_l_, is the apartment for the patterns.

The pig-iron, coals, &c. are placed either under sheds or in the open
air, round the above buildings; where are also a smith’s forge, a
carpenter’s shop, and an apartment mounted with vices for chipping and
rough cleaning the castings by chisels and files.

Such a foundry may be erected upon a square surface of about 80 yards in
each side, and will be capable, by casting in the afternoon and evening
of each day, partly in large and partly in small pieces, of turning out
from 700 to 800 tons per annum, with an establishment of 100 operatives,
including some moulding boys.

_Of making the Moulds._--1. Each mould ought to present the exact form
of its object.

2. It should have such solidity that the melted metal may be poured into
it, and fill it entirely without altering its shape in any point.

3. The air which occupies the vacant spaces in it, as well as the
carburetted gases generated by the heat, must have a ready vent; for if
they are but partially confined, they expand by the heat, and may crack,
even blow up the moulds, or at any rate become dispersed through the
metal, making it vesicular and unsound.

There are three distinct methods of making the moulds:--

1. In green sand; 2. In baked sand; 3. In loam.

To enumerate the different means employed to make every sort of mould
exceeds the limits prescribed to this work. I shall merely indicate for
each species of moulding, what is common to all the operations; and I
shall then describe the fabrication of a few such moulds as appear most
proper to give general views of this peculiar art.

_Moulding in green sand._--The name green is given to a mixture of the
sand as it comes from its native bed, with about one twelfth its bulk of
coal reduced to powder, and damped in such a manner as to form a porous
compound, capable of preserving the forms of the objects impressed upon
it. This sand ought to be slightly argillaceous, with particles not
exceeding a pin’s head in size. When this mixture has once served for a
mould, and been filled with metal, it cannot be employed again except
for the coarsest castings, and is generally used for filling up the
bottoms of fresh moulds.

For moulding any piece in green sand, an exact pattern of the object
must be prepared in wood or metal; the latter being preferable, as not
liable to warping, swelling, or shrinkage.

A couple of iron frames form a case or box, which serves as an envelope
to the mould. Such boxes constitute an essential and very expensive part
of the furniture of a foundry. It is a rectangular frame, without bottom
or lid, whose two largest sides are united by a series of cross bars,
parallel to each other, and placed from 6 to 8 inches apart.

The two halves of the box carry ears corresponding exactly with one
another; of which one set is pierced with holes, but the other has
points which enter truly into these holes, and may be made fast in them
by cross pins or wedges, so that the pair becomes one solid body. Within
this frame there is abundance of room for containing the pattern of the
piece to be moulded with its encasing sand, which being rammed into the
frame, is retained by friction against the lateral faces and cross bars
of the mould.

When a mould is to be formed, a box of suitable dimensions is taken
asunder, and each half, No. 1. and No. 2., is laid upon the floor of the
foundry. Green sand is thrown with a shovel into No. 1. so as to fill
it; when it is gently pressed in with a rammer. The object of this
operation is to form a plane surface upon which to lay in the pattern
with a slight degree of pressure, varying with its shape. No. 1. being
covered with sand, the frame No. 2. is laid upon it, so as to form the
box. No. 2. being now filled carefully with the green sand, the box is
inverted, so as to place No. 1. uppermost, which is then detached and
lifted off in a truly vertical position; carrying with it the body of
sand formed at the commencement of the operation. The pattern remains
imbedded in the sand of No. 2., which has been exactly moulded upon a
great portion of its surface. The moulder condenses the sand in the
parts nearest to the pattern, by sprinkling a little water upon it, and
trimming the ill-shaped parts with small iron trowels of different
kinds. He then dusts a little well-dried finely-sifted sand over all the
visible surface of the pattern, and of the sand surrounding it; this is
done to prevent adhesion when he replaces the frame No. 1.

He next destroys the preparatory smooth bed or area formed in this
frame, covers the pattern with green sand, replaces the frame 1. upon 2.
to reproduce the box, and proceeds to fill and ram No. 1., as he had
previously done No. 2. The object of this operation is to obtain very
exactly a concavity in the frame No. 1., having the shape of the part of
the model impressed coarsely upon the surface formed at the beginning,
and which was meant merely to support the pattern and the sand sprinkled
over it, till it got imbedded in No. 2.

The two frames in their last position, along with their sand, may be
compared to a box of which No. 1. is the lid, and whose interior is
adjusted exactly upon the enclosed pattern.

If we open this box, and after taking out the pattern, close its two
halves again, then pour in melted metal till it fill every void space,
and become solid, we shall obviously attain the wished-for end, and
produce a piece of cast iron similar to the pattern. But many
precautions must still be taken before we can hit this point. We must
first lead through the mass of sand in the frame No. 1., one or more
channels for the introduction of the melted metal; and though one may
suffice for this purpose, another must be made for letting the air
escape. The metal is run in by several orifices at once, when the piece
has considerable surface, but little thickness, so that it may reach the
remotest points sufficiently hot and liquid.

The parts of the mould near the pattern must likewise be pierced with
small holes, by means of wires traversing the whole body of the sand, in
order to render the mould more porous, and to facilitate the escape of
the air and the gases. Then, before lifting off the frame No. 1., we
must tap the pattern slightly, otherwise the sand enclosing it would
stick to it in several points, and the operation would not succeed.
These gentle jolts are given by means of one or more pieces of iron wire
which have been screwed vertically into the pattern before finally
ramming the sand into the frame No. 1., or which enter merely into holes
in the pattern. These pieces are sufficiently long to pass out through
the sand when the box is filled; and it is upon their upper ends that
the horizontal blows of the hammer are given; their force being
regulated by the weight and magnitude of the pattern. These rods are
then removed by drawing them straight out; after which the frame No. 1.
may be lifted off smoothly from the pattern.

The pattern itself is taken out, by lifting it in all its parts at once,
by means of screw pins adjusted at the moment. This manœuvre is
executed, for large pieces, almost always by several men, who while they
lift the pattern with one hand, strike it with the other with small
repeated blows to detach the sand entirely, in which it is generally
more engaged than it was in that of the frame No. 1. But in spite of all
these precautions, there are always some degradations in one or other of
the two parts of the mould; which are immediately repaired by the
workman with damp sand, which he applies and presses gently with his
trowel, so as to restore the injured forms.

Hitherto I have supposed all the sand rammed into the box to be of one
kind; but from economy, the green sand is used only to form the portion
of the mould next the pattern, in a stratum of about an inch thick; the
rest of the surrounding space is filled with the sand of the floor which
has been used in former castings. The interior layer round the pattern
is called in this case, _new sand_.

It may happen that the pattern is too complex to be taken out without
damaging the mould, by two frames alone; then 3 or more are mutually
adjusted to form the box.

When the mould, taken asunder into two or more parts, has been properly
repaired, its interior surface must be dusted over with wood charcoal
reduced to a very fine powder, and tied up in a small linen bag, which
is shaken by hand. The charcoal is thus sifted at the moment of
application, and sticks to the whole surface which has been previously
damped a little. It is afterwards polished with a fine trowel.
Sometimes, in order to avoid using too much charcoal, the surfaces are
finally dusted over with sand, very finely pulverized, from a bag like
the charcoal. The two frames are now replaced with great exactness, made
fast together by the ears, with wedged bolts laid truly level, or at the
requisite slope, and loaded with considerable weights. When the casting
is large, the charcoal dusting as well as that of fine sand, is
suppressed. Every thing is now ready for the introduction of the fused
metal.

_Moulding in baked or used sand._--The mechanical part of this process
is the same as of the preceding. But when the castings are large, and
especially if they are tall, the hydrostatic pressure of the melted
metal upon the sides of the mould cannot be counteracted by the force of
cohesion which the sand acquires by ramming. We must in that case adapt
to each of these frames a solid side, pierced with numerous small holes
to give issue to the gases. This does not form one body with the rest of
the frame, but is attached extemporaneously to it by bars and wedged
bolts. In general no ground coal is mixed with this sand. Whenever the
mould is finished, it is transferred to the drying stove, where it may
remain from 12 to 24 hours at most, till it be deprived of all its
humidity. The sand is then said to be baked, or annealed. The
experienced moulder knows how to mix the different sands placed at his
disposal, so that the mass of the mould as it comes out of the stove,
may preserve its form, and be sufficiently porous. Such moulds allow the
gases to pass through them much more readily than those made of _green_
sand; and in general the castings they turn out are less vesicular, and
smoother upon the surface. Sometimes in a large piece, the three kinds
of moulding, that in green sand, in baked sand, and in loam, are
combined to produce the best result.

_Moulding in loam._--This kind of work is executed from drawings of the
pieces to be moulded, without being at the expense of making patterns.
The mould is formed of a pasty mixture of clay, water, sand, and cow’s
hair, or other cheap filamentous matter, kneaded together in what is
called the loam mill. The proportions of the ingredients are varied to
suit the nature of the casting. When the paste requires to be made very
light, horse dung or chopped straw is added to it.

[Illustration: 468 469 470]

I shall illustrate the mode of fabricating loam moulds, by a simple
case, such as that of a sugar pan. _Fig._ 468. is the pan. There is laid
upon the floor of the foundry, an annular platform of cast-iron _a b_,
_fig._ 469.; and upon its centre _c_, rests the lower extremity of a
vertical shaft, adjusted so as to turn freely upon itself, while it
makes a wooden pattern _e f_, _fig._ 470., describe a surface of
revolution identical with the internal surface reversed of the boiler
intended to be made. The outline _e g_, of the pattern is fashioned so
as to describe the surface of the edge of the vessel. Upon the part _a d
b d_, _fig._ 469., of the flat cast-iron ring, there must next be
constructed, with bricks laid either flat or on their edge, and clay, a
kind of dome, _h i k_, _fig._ 470., from two to four inches thick,
according to the size and weight of the piece to be moulded. The
external surface of the brick dome ought to be everywhere two inches
distant at least, from the surface described by the arc _e_, _f_. Before
building up the dome to the point _i_, coals are to be placed in its
inside upon the floor, which may be afterwards kindled for drying the
mould. The top is then formed, leaving at _i_, round the upright shaft
of revolution, only a very small outlet. This aperture, as also some
others left under the edges of the iron ring, enable the moulder to
light the fire when it becomes necessary, and to graduate it so as to
make it last long enough without needing more fuel, till the mould be
quite finished and dry. The combustion should be always extremely slow.

Over the brick dome a pasty layer of loam is applied, and rounded with
the mould _g e f_; this surface is then coated with a much smoother
loam, by means of the concave edge of the same mould. Upon the latter
surface, the inside of the sugar pan is cast; the line _e g_ having
traced, in its revolution, a ledge _m_. The fire is now kindled, and as
the surface of the mould becomes dry, it is painted over by a brush,
with a mixture of water, charcoal powder, and a little clay, in order to
prevent adhesion between the surface already dried and the coats of clay
about to be applied to it. The board _g e f_ is now removed, and
replaced by another, _g´ e´ f´_, _fig._ 471., whose edge _e´ f´_
describes the outer surface of the pan. Over the surface _e_, _f_, a
layer of loam is applied, which is turned and polished so as to produce
the surface of revolution _e´ f´_, as was done for the surface _e f_;
only in the latter case, the line _e´ g´_ of the board does not form a
new shoulder, but rubs lightly against _m_.

The layer of loam included between the two surfaces _e f_, _e´ f´_, is
an exact representation of the sugar pan. When this layer is well dried
by the heat of the interior fire, it must be painted like the former.
The upright shaft is now removed, leaving the small vent hole through
which it passed to promote the complete combustion of the coal. There
must be now laid horizontally upon the ears of the platform _d d_,
_fig._ 469., another annular platform _p q_, like the former, but a
little larger, and without any cross-bar.

[Illustration: 471 472 473]

The relative position of these two platforms is shown in _fig._ 473.
Upon the surface _e´ f´_, _fig._ 472., a new layer of loam is laid, two
inches thick, of which the surface is smoothed by hand. Then upon the
platform _p q_, _fig._ 473., a brick vault is constructed, whose inner
surface is applied to the layer of loam. This contracts a strong
adherence with the bricks which absorb a part of its moisture, while the
coat of paint spread over the surface _e´ f´_, prevents it from sticking
to the preceding layers of loam. The brick dome ought to be built
solidly.

The whole mass is now to be thoroughly dried by the continuance of the
fire, the draught of which is supported by a small vent left in the
upper part of the new dome; and when all is properly dry, the two iron
platforms are adjusted to each other by pin points, and _p q_ is lifted
off, taking care to keep it in a horizontal position. Upon this platform
are removed the last brick dome, and the layer of loam which had been
applied next to it; the latter of which represents exactly by its inside
the mould of the surface _e´ f´_, that is of the outside of the pan. The
crust contained between _e f_ and _e´ f´_ is broken away, an operation
easily done without injury to the surface _e f_, which represents
exactly the inner surface of the pan; or only to the shoulder _m_,
corresponding to the edge of the vessel. The top aperture through which
the upright shaft passed must be now closed; only the one is kept open
in the portion of the mould lifted off upon _p q_; because through this
opening the melted metal is to be poured in the process of casting. The
two platforms being replaced above each other very exactly, by means of
the adjusting pin-points, the mould is completely formed, and ready for
the reception of the metal.

[Illustration: 474 475]

When the object to be moulded presents more complicated forms than the
one now chosen for the sake of illustration, it is always by analogous
processes that the workman constructs his loam moulds, but his sagacity
must hit upon modes of executing many things which at first sight appear
to be scarcely possible. Thus, when the forms of the interior and
exterior do not permit the mould to be separated in two pieces, it is
divided into several, which are nicely fitted with adjusting pins. More
than two cast-iron rings or platforms are sometimes necessary. When
ovals or angular surfaces must be traced instead of those of revolution,
no upright shaft is used, but wooden or cast-iron guides made on
purpose, along which the pattern cut-out board is slid according to the
drawing of the piece. Iron wires and claws are often interspersed
through the brick work to give it cohesion. The core, kernel, or inner
mould of a hollow casting is frequently fitted in when the outer shell
is moulded. I shall illustrate this matter in the case of a gas-light
retort, _fig._ 474. The core of the retort ought to have the form _e e e
e_, and be very solid, since it cannot be fixed in the outer mould, for
the casting, except in the part standing out of the retort towards _m
m_. It must be modelled in loam, upon a piece of cast-iron called a
_lantern_, made expressly for this purpose. The lantern is a cylinder or
a truncated hollow cone of cast iron, about half an inch thick; and
differently shaped for every different core. The surface is perforated
with holes of about half an inch in diameter. It is mounted by means of
iron cross bars, upon an iron axis, which traverses it in the direction
of its length. _Fig._ 475. represents a horizontal section through the
axis of the core; _g h_ is the axis of the lantern, figured itself at _i
k k i_; _o i i o_ is a kind of disc or dish, perpendicular to the axis,
open at _i i_, forming one piece with the lantern, whose circumference
_o o_ presents a curve similar to the section of the core, made at right
angles to its axis. We shall see presently the two uses for which this
dish is intended. The axis _g h_ is laid upon two gudgeons, and handles
are placed at each of its extremities, to facilitate the operation in
making the core. Upon the whole surface of the lantern, from the point
_h_ to the collet formed by the dish, a hay cord as thick as the finger
is wound. Even two or more coils may be applied, as occasion requires,
over which loam is spread to the exact form of the core, by applying
with the hand a board, against the dish _o o_, with its edge cut out to
the desired shape; as also against another dish, adjusted at the time
towards _h_; while by means of the handles a rotatory movement is given
to the whole apparatus.

The hay interposed between the lantern and the loam, which represents
the crust of the core, aids the adhesion of the clay with the cast iron
of the lantern, and gives passage to the holes in its surface, for the
air to escape through in the casting.

When the core is finished, and has been put into the drying stove, the
axis _g h_ is taken out, then the small opening which it leaves at the
point _h_, is plugged with clay. This is done by supporting the core by
the edges of the dish, in a vertical position. It is now ready to be
introduced into the hollow mould of the piece.

[Illustration: 476]

This mould executed in baked sand consists of three pieces, two of which
absolutely similar, are represented, _fig._ 476., at _p q_, the third is
shown at _r s_. The two similar parts _p q_, present each the
longitudinal half of the nearly cylindrical portion of the outer surface
of the gas retort; so that when they are brought together, the cylinder
is formed; _r s_ contains in its cavity the kind of hemisphere which
forms the bottom of the retort. Hence, by adding this part of the mould
to the end of the two others, the resulting apparatus presents in its
interior, the exact mould of the outside of the retort; an empty
cylindrical portion _t t_, whose axis is the same as that of the
cylinder _u u_, and whose surface, if prolonged, would be every where
distant from the surface _u u_, by a quantity equal to the desired
thickness of the retort. The diameter of the cylinder _t t_ is precisely
equal to that of the core, which is slightly conical, in order that it
may enter easily into this aperture _t t_, and close it very exactly
when it is introduced to the collet or neck.

[Illustration: 477]

The three parts of the mould and the core being prepared, the two pieces
_p q_, must first be united, and supported in an upright position; then
the core must be let down into the opening _t t_, _fig._ 477. When the
plate or disc _o o_ of the core is supported upon the mould, we must see
that the end of the core is every where equally distant from the edge of
the external surface _u u_, and that it does not go too far beyond the
line _q q_. Should there be an inaccuracy, we must correct it by slender
iron slips placed under the edge of the disc _o o_; then by means of a
cast iron cross, and screw bolts _v v_, we fix the core immovably. The
whole apparatus is now set down upon _r s_, and we fix with screw bolts
the plane surface _q q_ upon _r r_; then introduce the melted metal by
an aperture _z_, which has been left at the upper part of the mould.

When, instead of the example now selected, the core of the piece to be
cast must go beyond the mould of the external surface, as is the case
with a pipe open at each end, the thing is more simple, because we may
easily adjust and fix the core by its two ends.

In casting a retort, the metal is poured into the mould set upright. It
is important to maintain this position in the two last examples of
casting; for all the foreign matters which may soil the metal during its
flow, as the sand, the charcoal, gases, scoriæ, being less dense than
it, rise constantly to the surface. The hydrostatic pressure produced by
a high gate, or filling-in aperture, contributes much to secure the
soundness and solidity of the casting. This gate piece being
superfluous, is knocked off almost immediately after, or even before
the casting cools. Very long, and somewhat slender pieces, are usually
cast in moulds set up obliquely to the horizon. As the metal shrinks in
cooling, the mould should always be somewhat larger than the object
intended to be cast. The iron founder reckons in general upon a linear
shrinkage of a ninety-sixth part; that is one-eighth of an inch per
foot.

[Illustration: 478]

_Melting of the cast-iron._--The metal is usually melted in a cupola
furnace, of which the dimensions are very various. _Fig._ 478.
represents in plan, section, and elevation, one of these furnaces of the
largest size; being capable of founding 5 tons of cast-iron at a time.
It is kindled by laying a few chips of wood upon its bottom, leaving the
orifice _c_ open, and it is then filled up to the throat with coke. The
fire is lit at _c_, and in a quarter or half an hour, when the body of
fuel is sufficiently kindled, the tuyère blast is set in action. The
flame issues then by the mouth as well as the orifice _c_, which has
been left open on purpose to consolidate it by the heat. Without this
precaution, the sides which are made up in argillaceous sand after each
day’s work, would not present the necessary resistance. A quarter of an
hour afterwards, the orifice _c_ is closed with a lump of moist clay,
and sometimes, when the furnace is to contain a great body of melted
metal, the clay is supported by means of a small plate of cast-iron
fixed against the furnace. Before the blowing machine is set a going,
the openings _g g g_ had been kept shut. Those of them wanted for the
tuyères are opened in succession, beginning at the lowest, the tuyères
being raised according as the level of the fused iron stands higher in
the furnace. The same cupola may receive at a time from one to six
tuyères, through which the wind is propelled by the centrifugal action
of an excentric fan or ventilator. It does not appear to be ascertained
whether there be any advantage in placing more than two tuyères facing
each other upon opposite sides of the furnace. Their diameter at the
nozzle varies from 3 to 5 inches. They are either cylindrical or
slightly conical. A few minutes after the tuyères have begun to blow,
when the coke sinks in the furnace, alternate charges of coke and pig
iron must be thrown in. The metal begins to melt in about 20 minutes
after its introduction; and successive charges are then made every 10
minutes nearly; each charge containing from 2 cwt. to 5 cwt. of iron,
and a quantity proportional to the estimate given below. The amount of
the charges varies of course with the size of the furnace, and the speed
required for the operation. The pigs must be previously broken into
pieces weighing at most 14 or 16 pounds. The vanes of the blowing fan
make from 625 to 650 turns per minute. The two cupolas represented
_fig._ 478., and another alongside in the plan, may easily melt 6-1/2
tons of metal in 2-3/4 hours; that is 2-1/3 tons per hour. This result
is three or four times greater than what was formerly obtained in
similar cupolas, when the blast was thrown in from small nozzles with
cylinder bellows, moved by a steam engine of 10 horses power.

In the course of a year, a considerable foundry like that represented in
the plan, _fig._ 467., will consume about 300 tons of coke in melting
1240 tons of cast iron; consisting of 940 tons of pigs of different
qualities, and 300 tons of broken castings, gate-pieces, &c. Thus, it
appears that 48 pounds of coke are consumed for melting every 2 cwt. of
metal.

Somewhat less coke is consumed when the fusion is pushed more rapidly to
collect a great body of melted metal, for casting heavy articles; and
more is consumed when, as in making many small castings, the progress of
the founding has to be slackened from time to time; otherwise, the metal
would remain too long in a state of fusion, and probably become too cold
to afford sharp impressions of the moulds.

It sometimes happens that in the same day, with the same furnace, pieces
are to be cast containing several proportions of different kinds of
iron; in which case, to prevent an intermixture with the preceding or
following charges, a considerable bed of coke is interposed. Though
there be thus a little waste of fuel, it is compensated by the improved
adaptation of the castings to their specific objects. The founding
generally begins at about 3 o’clock, P. M., and goes on till 6 or 8
o’clock. One founder, aided by four labourers for charging, &c., can
manage two furnaces.

The following is the work of a well-managed foundry in Derby.

200 lbs. of coke are requisite to melt, or bring down (in the language
of the founders), 1 ton of cast-iron, after the cupola has been brought
to its proper heat, by the combustion in it of 9 baskets of coak,
weighing by my trials, 40 pounds each, = 360 lbs.

The chief talent of the founder consists in discovering the most
economical mixtures, and so compounding them as to produce the desired
properties in the castings. One piece, for example, may be required to
have great strength and tenacity to bear heavy weights or strains;
another must yield readily to the chisel or the file; a third must
resist sudden alternations of temperature; and a fourth must be pretty
hard.

The filling in of the melted metal is managed in two ways. For strong
pieces, whose moulds can be buried in the ground at 7 or 8 yards
distance from the furnace, the metal may be run in gutters, formed in
the sand of the floor, sustained by plates or stones. The clay plug is
pierced with an iron rod, when all is ready.

When from the smaller size, or greater distance of the moulds, the
melted metal cannot be run along the floor from the furnace, it is
received in cast-iron pots or ladles, lined with a coat of loam. These
are either carried by the hands of two or more men, or transported by
the crane. Between the successive castings, the discharge hole of the
furnace is closed with a lump of clay, applied by means of a stick,
having a small disc of iron fixed at its end.

After the metal is somewhat cooled, the moulds are taken asunder, and
the excrescences upon the edges of the castings are broken off with a
hammer. They are afterwards more carefully trimmed or chipped by a
chisel when quite cold. The loss of weight in founding is about 6-1/2
per cent. upon the pig iron employed. Each casting always requires the
melting of considerably more than its own weight of iron. This excess
forms the gates, false seams, &c.; the whole of which being deducted,
shows that 1 cwt. of coke is consumed for every 3 cwt. of iron put into
the furnace; for every 138 cwt. of crude metal, there will be 100 cwt.
of castings, 32 of refuse pieces, and 6 of waste.

Explanation of the plates.

_Manner of constructing the Mould of a Sugar-pan._

  _Fig._ 468. View of the pan.
    --   469. Flat ring of cast-iron for supporting the inner mould.
    --   470. Construction of the inner mould.
    --   471. Formation of the outer surface of the pan.
    --   472. Finished mould.
    --   473. Position of the two flat cast-iron rings, destined to
  sustain the moulds of the inner and the outer surface.

_Gas-retort Moulding._

    --   474. Vertical projection, perpendicular to the axis of the
              retort; and two sections, the one upright, the other
              horizontal.
    --   475. Construction of the core of the retort.
    --   476. Disposition of the outer mould.
    --   477. Adjustment of the core in the mould.
    --   478. _Cupola furnace._ It is 3 feet wide within, and 13-1/2
              high.

_m m_, solid body of masonry, as a basis to the furnace.

_b b_, octagonal platform of cast iron, with a ledge in which the plates
_a a a a_ are engaged.

_a a_, eight plates of cast iron, 1 inch thick, absolutely similar; only
one of them is notched at its lower part in _c_, to allow the melted
metal to run out, and two of the others have six apertures _g g g_, &c.
to admit the tuyères.

_c_, orifice for letting the metal flow out. A kind of cast iron gutter,
_e_, lined with loam is fitted to the orifice.

_d_, hoops of hammered iron, 4-1/4 inches broad; one half of an inch
thick for the bottom ones; and a quarter of an inch for the upper ones.
The intermediate hoops decrease in thickness from below upwards between
these limits.

_e_, cast iron gutter or spout, lined with loam, for running off the
metal.

_f f_, cylindrical piece of cast iron, for increasing the height and
draught of the furnace.

_g_, side openings for receiving the tuyères, of which there are six
upon each side of the furnace. Each of them may be shut at pleasure, by
means of a small cast iron plate _h_, made to slide horizontally in
grooves sunk in the main plate, pierced with the holes _g g_.

_k k_, interior lining of the surface, made of sand, somewhat
argillaceous, in the following way. After having laid at the bottom of
the furnace a bed of sand a few inches thick, slightly sloped towards
the orifice of discharge, there is set upright, in the axis of the
cupola, a wooden cylinder of its whole height, and of a diameter a
little less than that of the vacant space belonging to the top of the
furnace. Sand is to be then rammed in so as to fill the whole of the
furnace; after which the wooden cylinder is withdrawn, and the lining of
sand is cut or shaved away, till it has received the proper form.

This lining lasts generally 5 or 6 weeks, when there are 6 meltings
weekly.

_i i_, cast iron circular plate, through which the mouth of the furnace
passes, for protecting the lining in _k_ during the introduction of the
charges.

N N, level of the floor of the foundry. The portion of it below the
running out orifice consists of sand, so that it may be readily sunk
when it is wished to receive the melted metal in ladles or pots of large
dimensions.

[Illustration: 479]

The fan distributes the blast from the main pipe to three principal
points, by three branch tubes of distribution. A register, consisting of
a cast-iron plate sliding with friction in a frame, serves to intercept
the blast at any moment, when it is not desirable to stop the moving
power. A large main pipe of zinc or sheet iron is fitted to the orifice
of the slide valve. It is square at the beginning, or only rounded at
the angles; but at a little distance it becomes cylindrical, and
conducts the blast to the divaricating points. There, each of the
branches turns up vertically, and terminates at _b b_, _fig._ 479.,
where it presents a circular orifice of 7-1/2 inches. Upon each of the
upright pipes _b_, the one end of an elbow-tube of zinc _c c c c_,
_fig._ 479., is adjusted rather loosely, and the other end receives a
tuyère of wrought iron _d d_, through the intervention of a shifting
hose or collar of leather _c c d_, hooped with iron wire to both the
tube and the tuyère. The portion _c c c c_ may be raised or lowered, by
sliding upon the pipe _b_, in order to bring the nozzle of the tuyère _d
d_, to the requisite point of the furnace. The portion _c c c c_ may be
made also of wrought iron. A power of 4 horses is adequate to drive this
fan, for supplying blast to 3 furnaces.

The founders have observed the efflux of air was not the same when blown
into the atmosphere, as it was when blown into the furnaces; the
velocity of the fan, with the same impulsive power, being considerably
increased in the latter case. They imagine that this circumstance arises
from the blast being sucked in, so to speak, by the draught of the
furnace, and that the fan then supplied a greater quantity of air.

The following experimental researches show the fallacy of this opinion.
Two water syphons, _e e e_, _f f f_, made of glass tubes, one-fifth of
an inch in the bore, were inserted into the tuyère, containing water in
the portions _g g g_, _h h h_. The one of these _manometers_ for
measuring the pressure of the air was inserted at _k_, the other in the
centre of the nozzle. The size of this glass tube was too small to
obstruct in any sensible degree the outlet of the air. It was found that
when the tuyères of the fan discharged into the open air, the
expenditure by a nozzle of a constant diameter was proportional to the
number of the revolutions of the vanes. It was further found, that when
the speed of the vanes was constant, the expenditure by one or by two
nozzles was proportional to the total area of these nozzles. The
following formulæ give the volume of air furnished by the fan, when the
number of turns and the area of the nozzles are known.

            25·32 S n
  Volume =  ---------    (1)
            1,000,000

           0·86´6´7 S n
  Volume = ------------  (2)
             1,000,000

The volume is measured at 32° Fahr., under a pressure of 29·6 inches
barom.

S = is the total area of the orifices of the tuyères in square inches.

_n_ = the number of turns of the vanes in a minute.

After measuring the speed of the vanes blowing into the atmosphere, if
we introduce the nozzle of discharge into the orifice of the furnace, we
shall find that their speed immediately augments in a notable degree. We
might, therefore, naturally suppose that the fan furnishes more air in
the second case than in the first; but a little reflection will show
that it is not so. In fact, the air which issues in a cold state from
the tuyère encounters instantly in the furnace a very high temperature,
which expands it, and contributes, along with the solid matters with
which the furnace is filled, to diminish the facility of the discharge,
and consequently to retard the efflux by the nozzles. The oxygen gas
consumed is replaced by a like volume of carbonic acid gas, equally
expansible by heat. Reason leads us to conclude that less air flows from
the nozzles into the furnace than into the open atmosphere.

The increase in the velocity of the vanes takes place precisely in the
same manner, when after having made the nozzles blow into the
atmosphere, we substitute for these nozzles others of a smaller
diameter, instead of directing the larger ones into the furnace. Hence
we may conceive that the proximity of the charged furnace acts upon the
blast like the contraction of the nozzles. When the moving power is
uniform, and the velocity of the vanes remains the same, the quantity of
air discharged must also be the same in the two cases.

Two tuyères, one 5 inches in diameter, the other 4-1/2, and which,
consequently, presented a total area of 35-1/2 square inches, discharged
air into one of the furnaces, from a fan whose vanes performed 654 turns
in the minute. These two nozzles being briskly withdrawn from the
furnace, and turned round to the free air, while a truncated pasteboard
cone of 3-1/2 inches diameter was substituted for the nozzle of 4-1/2
inches, whereby the area of efflux was reduced to 29·3 square inches,
the velocity of the vanes continued exactly the same. The inverse
operation having been performed, that is to say, the two original
nozzles having been smartly replaced in the furnace, to discover whether
or not the moving power had changed in the interval of the experiment,
they betrayed no perceptible alteration of speed. From the measures
taken to count the speed, the error could not exceed 3 revolutions per
minute, which is altogether unimportant upon the number 654.

It follows, therefore, that when the vanes of the fan have the velocity
of 654 turns per minute, the expenditure by two nozzles, whose joint
area is 35-1/2 square inches, both blowing into a furnace, is to the
expenditure which takes place, when the same nozzles blow into the air,
as 35·5 is to 29·3; that is, a little more than 4-fifths.

If this be, as is probable, a general rule for areas and speeds
considerably different from the above, to find the quantity of air blown
into one or more furnaces by the fan, we should calculate the volume by
one of the above formulæ (1) or (2), and take 4-fifths of the result, as
the true quantity.

The fan A C here represented is of the best excentric form, as
constructed by Messrs. Braithwaite and Ericsson. D is the circular
orifice round the axis by which the air is admitted; and C C B is the
excentric channel through which the air is wafted towards the main
discharge pipe E.


FOUNTAIN; a stream of water rising up through the superficial strata of
the earth. See ARTESIAN WELLS.


FOXING, is a term employed by brewers to characterize the souring of
beer, in the process of its fermentation or ripening.


FRANKFORT BLACK; is made by calcining vine branches, and the other
refuse lees of the vinegar vats in Germany. They must be previously
washed.


FREEZING. (_Congelation_, Fr.; _Gefrierung_, Germ.) The three general
forms, solid, liquid, and gaseous, under one or other of which all kinds
of matter exist, seem to be immediately referrible to the influence of
heat; modifying, balancing, or subduing the attraction of cohesion.
Every solid may be liquefied, and every liquid may be vaporized, by a
certain infusion of caloric, whether this be regarded as a moving power,
or an elastic essence. The converse of this proposition is equally true;
for many gases, till lately styled permanent, may be liquefied, nay,
even solidified, by diminution of their temperature, either alone, or
aided by a condensing force, to bring their particles within the sphere
of aggregative attraction. When a solid is transformed into a liquid,
and a liquid into a gas or vapour, a quantity more or less considerable
of heat is absorbed, or becomes latent, to use the term of Dr. Black,
the celebrated discoverer of this great law of nature. When the opposite
transformation takes place, the heat absorbed is again emitted, or what
was latent becomes sensible caloric. Upon the first principle, or the
absorption of heat, are founded the various artificial methods of
producing cold and congelation.

Tables, exhibiting a collective view of all the Frigorific Mixtures
contained in Mr. Walker’s publication, 1808.

I.--Table consisting of Frigorific Mixtures, composed of ice, with
chemical salts and acids.

Frigorific Mixtures with Ice.

  +-------------------------------+-----------------+------------+
  |     MIXTURES.                 |   Thermometer   |Deg. of cold|
  |                               |      sinks.     | produced.  |
  +-------------------------------+-----------------+------------+
  |Snow, or pounded ice    2 parts|       }  to -5° |      *     |
  |Muriate of soda         1      |       }         |            |
  +-------------------------------+       }---------+------------+
  |Snow, or pounded ice    5 parts|       }         |            |
  |Muriate of soda         2      |From   }  to -12°|      *     |
  |Muriate of ammonia      1      |       }         |            |
  +-------------------------------+any    } --------+------------+
  |Snow, or pounded ice   24 parts|       }         |            |
  |Muriate of soda        10      |tempe- }  to -18°|      *     |
  |Muriate of ammonia      5      |       }         |            |
  |Nitrate of potash       5      |rature }         |            |
  +-------------------------------+       }---------+------------+
  |Snow, or pounded ice   12 parts|       }         |            |
  |Muriate of soda         5      |       }  to -25°|      *     |
  |Nitrate of ammonia      5      |       }         |            |
  +-------------------------------+-----------------+------------+
  |Snow                    3 parts|From +32° to -23°|     55     |
  |Diluted sulphuric acid  2      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    8 parts|From +32° to -27°|     59     |
  |Muriatic acid           5      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    7 parts|From +32° to -30°|     62     |
  |Diluted nitric acid     4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    4 parts|From +32° to -40°|     72     |
  |Muriate of lime         5      |                 |            |
  +-------------------------------+-----------------++-----------+
  |Snow                    2 parts|From +32° to -50°|     82     |
  |Cryst. muriate of lime  3      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    3 parts|From +32° to -51°|     83     |
  |Potash                  4      |                 |            |
  +-------------------------------+-----------------+------------+

N. B.--The reason for the omissions in the last column of the preceding
table is, the thermometer sinking in these mixtures to the degree
mentioned in the preceding column, and never lower, whatever may be the
temperature of the materials at mixing.

II.--Table, consisting of Frigorific Mixtures, having the power of
generating or creating cold, without the aid of ice, sufficient for all
useful and philosophical purposes, in any part of the world at any
season.

Frigorific Mixtures without Ice.

  +-------------------------------+-----------------+------------+
  |     MIXTURES.                 |   Thermometer   |Deg. of cold|
  |                               |      sinks.     | produced.  |
  +-------------------------------+-----------------+------------+
  |Muriate of ammonia      5 parts|                 |            |
  |Nitrate of potash       5      |From +50° to +10°|     40°    |
  |Water                  16      |                 |            |
  +-------------------------------+-----------------+------------+
  |Muriate of ammonia      5 parts|                 |            |
  |Nitrate of potash       5      |From +50° to +4° |     46     |
  |Sulphate of soda        8      |                 |            |
  |Water                  16      |                 |            |
  +-------------------------------+-----------------+------------+
  |Nitrate of ammonia      1 part |From +50° to +4° |     46     |
  |Water                   1      |                 |            |
  +-------------------------------+-----------------+------------+
  |Nitrate of ammonia      1 part |                 |            |
  |Carbonate of soda       1      |From +50° to -7° |     57     |
  |Water                   1      |                 |            |
  +-------------------------------+-----------------+------------+
  |Sulphate of soda        3 parts|From +50° to -3° |     53     |
  |Diluted nitric acid     2      |                 |            |
  +-------------------------------+-----------------+------------+
  |Sulphate of soda        6 parts|                 |            |
  |Muriate of ammonia      4      |From +50° to -10°|     60     |
  |Nitrate of potash       2      |                 |            |
  |Diluted nitric acid     4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Sulphate of soda        6 parts|                 |            |
  |Nitrate of ammonia      5      |From +50° to -14°|     64     |
  |Diluted nitric acid     4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Phosphate of soda       9 parts|From +50° to -12°|     62     |
  |Diluted nitric acid     4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Phosphate of soda       9 parts|                 |            |
  |Nitrate of ammonia      6      |From +50° to -21°|     71     |
  |Diluted nitric acid     4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Sulphate of soda        8 parts|From +50° to 0°  |     50     |
  |Muriatic acid           5      |                 |            |
  +-------------------------------+-----------------+------------+
  |Sulphate of soda        5 parts|From +50° to +3° |     47     |
  |Diluted sulphuric acid  4      |                 |            |
  +-------------------------------+-----------------+------------+

N. B.--If the materials are mixed at a warmer temperature than that
expressed in the table, the effect will be proportionably greater; thus,
if the most powerful of these mixtures be made when the air is +85°, it
will sink the thermometer to +2°.

III.--Table consisting of Frigorific Mixtures selected from the
foregoing Tables, and combined so as to increase or extend cold to the
extremest degrees.

Combinations of Frigorific Mixtures.

  +-------------------------------+-----------------+------------+
  |     MIXTURES.                 |   Thermometer   |Deg. of cold|
  |                               |      sinks.     | produced.  |
  +-------------------------------+-----------------+------------+
  |Phosphate of soda       5 parts|                 |            |
  |Nitrate of ammonia      3      |From 0° to -34°  |     34     |
  |Diluted nitric acid     4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Phosphate of soda       3 parts|                 |            |
  |Nitrate of ammonia      2      |From -34° to -50°|     16     |
  |Diluted mixed acids     4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    3 parts|From 0° to -46°  |     46     |
  |Diluted nitric acid     2      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    8 parts|                 |            |
  |Diluted sulphuric acid  3      |From -10° to -56°|     46     |
  |Diluted nitric acid     3      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    1 part |From -20° to -60°|     40     |
  |Diluted sulphuric acid  1      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    3 parts|From +20° to -48°|     68     |
  |Muriate of lime         4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    3 parts|From +10° to -54°|     64     |
  |Muriate of lime         4      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    2 parts|From -15° to -68°|     53     |
  |Muriate of lime         3      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    1 part |From 0° to -66°  |     66     |
  |Cryst. muriate of lime  2      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    1 part |From -40° to -73°|     33     |
  |Cryst. muriate of lime  3      |                 |            |
  +-------------------------------+-----------------+------------+
  |Snow                    8 parts|From -68° to -91°|     23     |
  |Diluted sulphuric acid 10      |                 |            |
  +-------------------------------+-----------------+------------+

N. B.--The materials in the first column are to be cooled, previously to
mixing, to the temperature required, by mixtures taken from either of
the preceding tables.

Water absorbs 1000 degrees of heat in becoming vapour; whence, if placed
in a saucer within an exhausted receiver, over a basin containing strong
sulphuric acid, it will freeze by the rapid absorption of its heat into
the vapour so copiously formed under these circumstances.

But the most powerful means of artificial refrigeration is afforded by
the evaporation of liquefied carbonic acid gas; for the frozen carbonic
acid thus obtained, has probably a temperature 100° under zero; so that
when a piece of it is laid upon quicksilver, it instantly congeals this
metal. The more copious discussion of this subject belongs to chemical
science.


FRENCH BERRIES; Berries of Avignon.


FRICTION, counteraction of; see LUBRICATION.


FRIT; see ENAMEL and GLASS.


FUEL; (_Combustible_, Fr; _Brennstoff_, Germ.).

Such combustibles as are used for fires or furnaces are called fuel, as
wood, turf, pitcoal. These differ in their nature, and in their power of
giving heat.

I. Wood, which is divided into hard and soft. To the former belong the
oak, the beech, the alder, the birch, and the elm; to the latter, the
fir, the pine of different sorts, the larch, the linden, the willow, and
the poplar.

Under like dryness and weight, different woods are found to afford equal
degrees of heat in combustion. Moisture diminishes the heating power in
three ways; by diminishing the relative weight of the ligneous matter,
by wasting heat in its evaporation, and by causing slow and imperfect
combustion. If a piece of wood contain, for example, 25 per cent. of
water, then it contains only 75 per cent. of fuel, and the evaporation
of that water will require 1/28 part of the weight of the wood. Hence
the damp wood is of less value in combustion by 8/28 or 2/7 than the
dry. The quantity of moisture in newly felled wood amounts to from 20 to
50 per cent.; birch contains 30, oak 35, beech and pine 39, alder 41,
fir 45. According to their different natures, woods which have been
felled and cleft for 12 months contain still from 20 to 25 per cent. of
water. There is never less than 10 per cent. present, even when it has
been kept long in a dry place, and though it be dried in a strong heat,
it will afterwards absorb 10 or 12 per cent. of water. If it be too
strongly kiln dried, its heating powers are impaired by the commencement
of carbonization, as if some of its hydrogen were destroyed. It may be
assumed as a mean of many experimental results, that 1 pound of
artificially dried wood will heat 35 pounds of water from the freezing
to the boiling point; and that a pound of such wood as contains from 20
to 25 per cent. of water will heat 26 pounds of ice-cold water to the
same degree. It is better to buy wood by measure than by weight, as the
bulk is very little increased by moisture. The value of different woods
for fuel is inversely as their moisture, and this may easily be
ascertained by taking their shavings, drying them in a heat of 140° F.,
and seeing how much weight they lose.

From every combustible the heat is diffused either by radiation or by
direct communication to bodies in contact with the flame. In a wood fire
the quantity of radiating heat is to that diffused by the air, as 1 to
3; or it is one fourth of the whole heating power.

II. _Charcoal._ The different charcoals afford, under equal weights,
equal quantities of heat. We may reckon, upon an average, that a pound
of dry charcoal is capable of heating 73 pounds of water from the
freezing to the boiling point; but when it has been for some time
exposed to the air, it contains at least 10 per cent. of water, which is
partially decomposed in the combustion into carburetted hydrogen, which
causes flame, whereas pure dry charcoal emits none.

A cubic foot of charcoal from soft wood weighs upon an average from 8 to
9 pounds, and from hard wood 12 to 13 pounds; and hence the latter are
best adapted to maintain a high heat in a small compass. The radiating
heat from charcoal fires constitutes one third of the whole emitted.

III. _Pitcoal._ The varieties of this coal are almost indefinite, and
give out very various quantities of heat in their combustion. The carbon
is the heat-giving constituent, and it amounts, in different coals, to
from 75 to 95 per cent. One pound of good pitcoal will, upon an average,
heat 60 pounds of water from the freezing to the boiling point. Small
coal gives out three-fourths of the heat of the larger lumps. The
radiating heat emitted by burning pitcoal is greater than that by
charcoal.

IV. _The coke of pitcoal._--The heating power of good coke is to that of
pitcoal as 75 to 69. One pound of the former will heat 65 pounds of
water from 32° to 212°; so that its power is equal to nine-tenths of
that of wood charcoal.

V. _Turf or peat._--One pound of this fuel will heat from 25 to 30
pounds of water from freezing to boiling. Its value depends upon its
compactness and freedom from earthy particles; and its radiating power
is to the whole heat it emits in burning, as 1 to 3.

VI. _Carburetted hydrogen or coal gas._--One pound of this gas, equal to
about 24 cubic feet, disengages in burning, as much heat as will raise
76 pounds of water from the freezing to the boiling temperature.

In the following table the fourth column contains the weight of
atmospherical air, whose oxygen is required for the complete combustion
of a pound of each particular substance.

  +--------------------------+-----------+-----------+-----------+
  | Species of combustible.  | Pounds of | Pounds of | Weight of |
  |                          |water which|  boiling  |atmospheric|
  |                          |a pound can|   water   |air at 32°,|
  |                          | heat from |evaporated | to burn 1 |
  |                          |0° to 212°.|by 1 pound.|  pound.   |
  +--------------------------+-----------+-----------+-----------+
  |Perfectly dry wood        |   35·00   |    6·36   |    5·96   |
  |Wood in its ordinary state|   26·00   |    4·72   |    4·47   |
  |Wood charcoal             |   73·00   |   13·27   |   11·46   |
  |Pitcoal                   |   60·00   |   10·90   |    9·26   |
  |Coke                      |   65·00   |   11·81   |   11·46   |
  |Turf                      |   30·00   |    5·45   |    4·60   |
  |Turf charcoal             |   64·00   |   11·63   |    9·86   |
  |Carburetted hydrogen gas  |   76·00   |   13·81   |   14·58   |
  |Oil    }                  |           |           |           |
  |Wax    }                  |   78·00   |   14·18   |   15·00   |
  |Tallow }                  |           |           |           |
  |Alcohol of the shops      |   52·60   |    9·56   |   11·60   |
  +--------------------------+-----------+-----------+-----------+

The quantity of air stated in the fourth column, is the smallest
possible required to burn the combustible, and is greatly less than
would be necessary in practice, where much of the air never comes into
contact with the burning body, and where it consequently never has its
whole oxygen consumed. The heating power stated in the second column is
also the maximum effect, and can seldom be realized with ordinary
boilers. The draught of air usually carries off at least 1/7 of the
heat, and more if its temperature be very high when it leaves the
vessel. In this case it may amount to one half of the whole heat or
more; without reckoning the loss by radiation and conduction, which
however may be rendered very small by enclosing the fire and flues
within proper non-conducting and non-radiating materials.

It appears that in practice, the quantity of heat which may be obtained
from any combustible in a properly mounted apparatus, must vary with the
nature of the object to be heated. In heating chambers by stoves, and
water boilers by furnaces, the effluent heat in the chimney which
constitutes the principal waste, may be reduced to a very moderate
quantity, in comparison of that which escapes from the best constructed
reverberatory hearth. In heating the boilers of steam engines, one pound
of coal is reckoned adequate to convert 7-1/2 pounds of boiling water
into vapour; or to heat 41-1/4 pounds of water from the freezing to the
boiling point. One pound of fir of the usual dryness will evaporate 4
pounds of water, or heat 22 pounds to the boiling temperature; which is
about two-thirds of the maximum effect of this combustible. According to
Watt’s experiments upon the great scale, one pound of coal can boil off
with the best built boiler, 9 pounds of water; the deficiency from the
maximum effect being here 10/57, or nearly one-sixth.

In many cases the hot air which passes into the flues or chimneys may be
beneficially applied to the heating, drying, or roasting of objects;
but care ought to be taken that the draught of the fire be not thereby
impaired, and an imperfect combustion of the fuel produced. For at a low
smothering temperature both carbonic oxide and carburetted hydrogen may
be generated from coal, without the production of much heat in the
fire-place.

To determine exactly the quantity of heat disengaged by any combustible
in the act of burning, three different systems of apparatus have been
employed; 1. the calorimeter of Lavoisier and Laplace, in which the
substance is burned in the centre of a vessel, whose walls are lined
with ice; and the amount of ice melted, measures the heat evolved; 2.
the calorimeter of Watt and Rumford, in which the degree of heat
communicated to a given body of water affords the measure of
temperature; and 3. by the quantity of water evaporated by different
kinds of fuel in similar circumstances.

[Illustration: 480]

If our object be to ascertain the relative heating powers of different
kinds of fuel, we need not care so much about the total waste of heat in
the experiments, provided it be the same in all; and therefore they
should be burned in the same furnace, and in the same way. But the more
economically the heat is applied, the greater certainty will there be in
the results. The apparatus, _fig._ 480., is simple and well adapted to
make such comparative trials of fuel. The little furnace is covered at
top, and transmits its burned air by _c_, through a spiral tube immersed
in a cistern of water, having a thermometer inserted near its top, and
another near its bottom, into little side orifices _a a_, while the
effluent air escapes from the upright end of the tube _b_. Here also a
thermometer bulb may be placed. The average indication of the two
thermometers gives the mean temperature of the water. As the water
evaporates from the cistern, it is supplied from a vessel placed
alongside of it. The experiment should be begun when the furnace has
acquired an equability of temperature. A throttle valve at _c_ serves to
regulate the draught, and to equalize it in the different experiments by
means of the temperature of the effluent air. When the water has been
heated the given number of degrees, which should be the same in the
different experiments, the fire may be extinguished, the remaining fuel
weighed, and compared with the original quantity. Care should be taken
to make the combustion as vivid and free from smoke as possible.


FULGURATION; designates the sudden brightening of the melted gold and
silver in the cupel of the assayer, when the last film of vitreous lead
and copper leaves their surface.


FULLER’S EARTH, (_Terre à foulon_, _Argile Smectique_, Fr.;
_Walkererde_, Germ.) is a soft, friable, coarse or fine grained mass of
lithomarge clay. Its colour is greenish, or yellowish gray; it is dull,
but assumes a fatty lustre upon pressure with the fingers, feels
unctuous, does not adhere to the tongue, and has a specific gravity
varying from 1·82 to 2·19. It falls down readily in water, into a fine
powder, with extrication of air bubbles, and forms a non-plastic paste.
It melts at a high heat into a brown slag. Its constituents are 53·0
silica; 10·0 alumina; 9·75 red oxide of iron; 1·25 magnesia; 0·5 lime;
24 water, with a trace of potash. Its cleansing action upon woollen
stuffs depends upon its power of absorbing greasy matters. It should be
neither tenacious nor sandy; for in the first case, it would not diffuse
itself well through water, and in the second it would abrade the cloth
too much. The finely divided silica is one of its useful ingredients.

Fuller’s earth is found in several counties of England; but in greatest
abundance in Bedfordshire, Berkshire, Hampshire, and Surry.

In the county of Surry there are great quantities of fuller’s earth
found about Nutfield, Ryegate, and Blechingley, to the south of the
Downs, and some, but of inferior quality, near Sutton and Croydon, to
the north of them. The most considerable pits are near Nutfield, between
which place and Ryegate, particularly on Redhill, about a mile to the
east of Ryegate, it lies so near the surface as frequently to be turned
up by the wheels of the waggons. The fuller’s earth to the north of the
road between Redhill and Nutfield, and about a quarter of a mile from
the latter place, is very thin; the seam in general is thickest on the
swell of the hill to the south of the road. It is not known how long
this earth has been dug in Surry; the oldest pit now wrought is said to
have lasted between 50 and 60 years, but it is fast wearing out. The
seam of fuller’s earth dips in different directions. In one, if not in
more cases, it inclines to the west with a considerable angle. There are
two kinds of it, the blue and the yellow: the former, on the eastern
side of the pit, is frequently within a yard of the surface, being
covered merely with the soil--a tough, wet, clayey loam. A few yards to
the west, the blue kind appears with an irony sand-stone, of nearly two
yards in thickness, between it and the soil. The blue earth in this pit
is nearly 16 feet deep. In some places the yellow kind is found lying
upon the blue; there seems, indeed, to be no regularity either in the
position or inclination of the strata where the fuller’s earth is found,
nor any mark by which its presence could be detected. It seems rather
thrown in patches than laid in any continued or regular vein. In the
midst of the fuller’s earth are often found large pieces of stone of a
yellow colour, translucent and remarkably heavy, which have been found
to be sulphate of barytes, encrusted with quartzose crystals. These are
carefully removed from the fuller’s earth, as the workmen say they often
spoil many tons of it which lie about them. There is also found with the
yellow fuller’s earth a dark brown crust, which the workmen consider as
injurious also. In Surry the price of fuller’s earth seems to have
varied very little, at least for these last 80 years. In 1730, the price
at the pit was 6_d._ a sack, and 6_s._ per load or ton. In 1744, it was
nearly the same. It is carried in waggons, each drawing from three to
four tons, to the beginning of the iron railway near Westham, along
which it is taken to the banks of the Thames, where it is sold at the
different wharfs for about 25_s._ or 26_s._ per ton. It is then shipped
off either to the north or west of England.

The next characteristic stratum, owing to its forming a ridge of
conspicuous hills through the country, is the Woburn land, a thick
ferruginous stratum, which below its middle contains a stratum of
fuller’s earth. This is thicker and more pure in Aspley and Hogstye-end,
two miles north-west of Woburn, than in any known place.

Fuller’s earth is found at Tillington, and consumed in the neighbouring
fulling mills.

Mode of preparing fuller’s earth:--

After baking it is thrown into cold water, where it falls into powder,
and the separation of the coarse from the fine is effectually
accomplished, by a simple method used in the dry colour manufactories,
called washing over. It is done in the following manner: Three or four
tubs are connected on a line by spouts from their tops; in the first the
earth is beat and stirred, and the water, which is continually running
from the first to the last through intermediate ones, carries with it
and deposits the fine, whilst the coarse settles in the first. The
advantages to be derived from this operation are, that the two kinds
will be much fitter for their respective purposes of cleansing coarse or
fine cloth; for without baking the earth they would be unfit, as before
noticed, to incorporate so minutely with the water in its native state;
it would neither so readily fall down, nor so easily be divided into
different qualities, without the process of washing over. When fuel is
scarce for baking the earth, it is broken into pieces of the same size,
as mentioned above, and then exposed to the heat of the sun.

The various uses of fuller’s earth may be shortly explained. According
to the above method, the coarse and fine of one pit being separated, the
first is used for cloths or an inferior, and the second for those of a
superior quality. The yellow and the blue earths of Surry are of
different qualities naturally, and are like the above, obtained
artificially, and used for different purposes. The former, which is
deemed the best, is employed in fulling the kerseymeres and finer cloths
of Wiltshire and Gloucestershire, whilst the blue is principally sent
into Yorkshire for the coarser cloths. Its effects on these cloths is
owing to the affinity which alumine has for greasy substances; it unites
readily with them, and forms combinations which easily attach themselves
to different stuffs, and thereby serve the purpose of mordants in some
measure. The fullers generally apply it before they use the soap.


FULLING; for the theory of the process, see FELTING, and WOOL.


FULLING MILL. Willan and Ogle obtained a patent in 1825 for improved
fulling machinery, designed to act in a similar way to the ordinary
stocks, in which cloths are beaten, for the purpose of washing and
thickening them; but the standard and the bed of the stocks are made of
iron instead of wood as heretofore; and a steam vessel is placed under
the bed, for heating the cloths during the operation of fulling; whereby
their appearance is said to be greatly improved.

[Illustration: 480*]

_Fig._ 480*. is a section of the fulling machine or stocks; _a_, is a
cast-iron pillar, made hollow for the sake of lightness; _b_, is the bed
of the stocks, made also of iron, and polished smooth, the side of the
stock being removed to shew the interior; _c_, is the lever that carries
the beater _d_. The cloths are to be placed on the bed _b_, at bottom,
and water allowed to pass through the stock, when by the repeated blows
of the beater _d_, which is raised and let fall in the usual way, the
cloths are beaten, and become cleansed and fulled.

A part of the bed at _e_, is made hollow, for the purpose of forming a
steam box, into which steam from a boiler is introduced by a pipe with a
stop-cock. This steam heats the bed of the stock, and greatly
facilitates, as well as improves the process of cleansing and fulling
the cloths.

The smoothness of the surface of the polished metal, of which the bed of
the stock is constituted, is said to be very much preferable to the
roughness of the surface of wood of which ordinary fulling stocks are
made, as by these iron stocks less of the nap or felt of the cloth is
removed, and its appearance when finished is very much superior to
cloths fulled in ordinary stocks.

In the operation of fulling, the cloths are turned over on the bed, by
the falling of the beaters, but this turning over of the cloths will
depend in a great measure upon the form of the front or breast of the
stock. In these improved stocks therefore, there is a contrivance by
which the form of the front may be varied at pleasure, in order to suit
cloths of different qualities; _f_, is a movable curved plate,
constituting the front of the stock; its lower part is a cylindrical
rod, extending along the entire width of the bed, and being fitted into
a recess, forms a hinge joint upon which the curved plate moves; _g_, is
a rod attached to the back of the curved plate _f_, with a screw thread
upon it; this rod passes through a nut _h_, and by turning this nut, the
rod is moved backward or forward, and consequently, the position of the
curved plate altered.

The nut _h_, is a wheel with teeth, taking into two other similar
toothed wheels, one on each side of it, which are likewise the nuts of
similar rods jointed to the back of the curved plate _f_; by turning the
central wheel, therefore, which may be done by a winch, the other two
wheels are turned also, and the curved plate moved backward or forward.
At the upper part of the plate there are pins passing through curved
slots, which act as guides when the plate is moved.

The patentees state in conclusion, that steam has been employed before
for heating cloths while fulling them, they therefore do not exclusively
claim its use, except in the particular way described; the advantages
arising from the construction of iron stocks, with polished surfaces in
place of wooden ones, together with the movable curved plates described,
are in their opinion “sufficiently important to constitute a patent
right.”


FULMINATES, or _fulminating powders_. Of these explosive compounds,
there are several species; such as fulminating gold, mercury, platinum,
silver; besides the old fusible mixture of nitre, sulphur, and potash.
The only kind at all interesting in a manufacturing point of view is the
fulminate of mercury, now so extensively used as a priming to the caps
of percussion locks. Having published a paper in the Journal of the
Royal Institution for 1831, upon gunpowder (see GUNPOWDER), the result
of an elaborate suite of experiments, I was soon afterwards requested by
the Hon. the Board of Ordnance to make such researches as would enable
me to answer, in a satisfactory practical manner, a series of questions
upon fulminating powders, subservient to the future introduction of
percussion musquets into the British army. The following is a verbatim
copy of my report upon the subject:--

_To the Secretary of the Board of Ordnance._

“SIR,--I have the honour of informing you, for the instruction of the
Honourable the Master General and the Board of Ordnance, that the
researches on fulminating mercury, which I undertook by their desire,
have been brought to a satisfactory conclusion, after a numerous,
diversified, and somewhat hazardous series of experiments. The following
are the questions submitted to me, with their respective answers:--

_Question 1._ What proportions of mercury, with nitric acid and alcohol
of certain strengths, will yield the greatest quantity of pure fulminate
of mercury?

_Answer._ One hundred parts, by weight, of mercury, must be dissolved
with a gentle heat, in 1000 parts (also by weight) of nitric acid, spec.
gr. 1·4; and this solution, at the temperature of about 130° Fahr. must
be poured into 830 parts by weight of alcohol, spec. gr. 0·830.--_Note._
830 parts of such alcohol, by weight, constitute 1000 by measure; and
1000 parts of such nitric acid, by weight, constitute 740 by measure.
Hence, in round numbers, one ounce weight of quicksilver must be
dissolved in 7-1/2 oz. measures of the above designated nitric acid, and
the resulting solution must be poured into 10 oz. measures of the said
alcohol.

_Question 2._ What is the most economical and safe process for
conducting the manipulation, either as regards the loss of nitrous gas
and residuum, or as respects danger to the operator; also, what is the
readiest and safest mode of mixing the fulminate intimately with its due
proportions of common gunpowder.

_Answer._ The mercury should be dissolved in the acid in a glass retort,
the beak of which is loosely inserted into a large balloon or bottle of
glass or earthenware, whereby the offensive fumes of the nitrous gas
disengaged during the solution, are, in a considerable measure,
condensed into liquid acid, which should be returned into the retort. As
soon as the mercury is all dissolved, and the solution has acquired the
prescribed temperature of about 130°, it should be slowly poured,
through a glass or porcelain funnel, into the alcohol contained in a
glass matrass or bottle capable of holding fully 6 times the bulk of the
mixed liquids. In a few minutes bubbles of gas will proceed from the
bottom of the liquid; these will gradually increase in number and
magnitude till a general fermentative commotion, of a very active kind,
is generated, and the mixture assumes a somewhat frothy appearance. A
white voluminous gas now issues from the orifice of the matrass, which
is very combustible, and must be suffered to escape freely into the air,
at a distance from any flame. These fumes consist of an ethereous gas,
holding mercury in suspension or combination. I have made many
experiments with the view of condensing this gas, or, at least, the
mercury, but with manifest disadvantage to the perfection of the process
of producing fulminate. When the said gas is transmitted, through a
glass tube, into a watery solution of carbonate of soda, a little oxide
of mercury is, no doubt, recovered; but the pressure on the fermentative
mixture, though slight, necessary to the displacement of the soda
solution, seems to obstruct or impair the generation of the fulminate;
this effect is chiefly injurious towards the end of the operation when
the gaseous fumes are strongly impregnated with nitrous gas. When this
is not allowed freely to come off, a portion of subnitrate or nitrate of
mercury is apt to be formed, to the injury of the general process and
the product.

As soon as the effervescence and concomitant emission of gas are
observed to cease, the contents of the matrass should be turned out upon
a paper double filter, fitted into a glass or porcelain funnel, and
washed by the affusion of cold water till the drainings no longer redden
litmus paper. The powder adhering to the matrass should be washed out
and thrown on the filter by the help of a little water. Whenever the
filter is thoroughly drained, it is to be lifted out of the funnel, and
opened out on plated copper or stone ware, heated to 212° Fahr. by steam
or hot water. The fulminate being thus dried, is to be put up in paper
parcels of about 100 grains each; the whole of which may be afterwards
packed away in a tight box, or a bottle with a cork stopper. The
excellence of the fulminate may be ascertained, by the following
characters. It consists of brownish-gray small crystals which sparkle in
the sun, are transparent when applied to a slip of glass with a drop of
water, and viewed by transmitted light. These minute spangles are
entirely soluble in 130 times their weight of boiling water; that is to
say, an imperial pint of boiling water will dissolve 67 grs. of pure
fulminate. Whatever remains indicates impurity. From that solution
beautiful pearly spangles of fulminate fall down as the liquid cools.

It may now be proper to show within what nice and narrow limits the best
proportions of the ingredients used in making the fulminate of mercury
lie. The following are selected from among many experiments instituted
to determine that point, as well as the most economical process.

1. According to the formula given by the celebrated chemist Berzelius,
in the 4th vol. of his “Traité de Chimie,” recently published (p. 383.),
the mercury should be dissolved in 12 times its weight of nitric acid
sp. gr. 1·375; and alcohol of sp. gr. 0·850, amounting to 16·3 times the
weight of the mercury, should be poured at intervals into the nitric
solution. The mixture is then to be heated till effervescence with the
characteristic cloud of gas appears. On the action becoming violent,
alcohol is to be poured in from time to time to repress it, till
additional 16·3 parts have been employed.

On this process I may remark, that it is expensive, troublesome,
dangerous, and unproductive of genuine pure fulminate. One fifth more
nitric acid is expended very nearly than what is necessary, and almost
four times the weight of alcohol which is beneficial. Of alcohol at
0·83, 8·3 parts by weight are sufficient; whereas Berzelius prescribes
nearly 4 times this quantity in weight, though the alcohol is somewhat
weaker, being of sp. gr. 0·850. By using such an excess of alcohol, much
of the fulminate is apt to be revived into globules of quicksilver at
the end of the process, as I showed in my paper on this subject
published in the Journal of the Royal Institution two years ago. There
is no little hazard in pouring the alcohol into the nitric solution; for
at each effusion an explosive blast takes place, whereas by pouring the
solution into the alcohol, as originally enjoined by the Hon. Mr.
Howard, the inventor of the process, no danger whatever is incurred. 100
parts of mercury treated in the way recommended by Berzelius afforded me
only 112 parts of fulminate, instead of the 130 obtained by my much more
economical and safe proportions and process from the same weight of
quicksilver.

2. If 10 parts of nitric acid of sp. gr. 1·375 be used for dissolving 1
of quicksilver, and if 14 parts of alcohol of sp. gr. 0·85 be thereafter
mixed with the solution, the product of such proportions will either be
not granular, and therefore not fulminating, or it will be partially
granular and partially pulverulent, being a mixture of fulminate and
subnitrate of mercury ill adapted for priming detonating caps. Instead
of 130 parts of genuine fulminate, as I do obtain, probably not more
than 10 parts of powder will be produced, and that of indifferent
quality. In fact, whenever the ethereous fermentation is defective, or
not vigorous, little true fulminate is generated; but much of the
mercury remains in the acidulated alcoholic liquid.

3. If the alcohol be poured in successive portions, and of proper
strength (sp. gr. 0·83) into a proper nitric solution of mercury, the
explosive action which accompanies each effusion dissipates much of the
alcohol, and probably impairs the acid, so that the subsequent ethereous
fermentation is defective, and little good fulminate is formed. From 100
parts of mercury submitted to this treatment, I obtained in one
experiment carefully made, only 51 parts of a powder, which was
impalpable, had a cream colour, and was not explosive either by heat or
percussion.

4. When, with 100 parts of mercury, 800 of nitric acid of sp. gr. 1·375
are employed with 650 of alcohol of sp. gr. 846, no fulminate whatever
is generated.

5. When with the proper proportions of mercury, acid, and alcohol, the
process is advanced into a proper energy of fermentative commotion, if
the matrass be immersed in cold water so as materially to repress that
action, the process will be impaired, and will turn out ultimately
defective both as to the quantity and quality of the fulminate. It is
therefore evident that a certain energy or vivacity of etherization is
essential to the full success of this curious process, and that any
thing which checks it, or obstructs its taking place, is injurious and
to be avoided.

When my proportions are observed in making fulminating mercury, somewhat
less than one fourth of the nitric acid used in making the solution
remains in the alcoholic mixture along with the fulminate. When other
proportions are taken, much more acid remains. This acid is not
recoverable to any useful or economical purpose, nor is the alcohol that
is associated with it. Many distillations with various reagents have led
me to this practical conclusion. In fact, when the process is most
complete, as described in the first paragraph, the alcohol is entirely
and profitably employed in etherization, and generating fulminic acid.

I have made a series of analytical experiments on the pure fulminate of
mercury, with the view of determining its composition, the quantity of
quicksilver present in it, and consequently the loss of mercury in the
operation. I have stated that my maximum product of fulminate from 100
grs. of quicksilver is 130 grs. Occasionally from slight differences in
the temperature of the mixture, or the ambient atmosphere, 2 grs. less
may be obtained.

A. I dissolved 130 grs. with a gentle heat in muriatic acid contained in
a small matrass, adding a few drops of the nitric to quicken the
solution. On evaporating it to dryness, with much care to avoid
volatilization of the salt, I obtained 125 grs. of corrosive sublimate
or bi-chloride of mercury. But 125 grs. of this bi-chloride contain only
91·1 grs. of quicksilver. Therefore, by this experiment, 130 grs. of
fulminate contain no more than 91·1 of mercury, indicating an exhalation
of 8·9 parts in the form of fumes, or a retention in the residuary
liquid of some of these 8·9 parts, out of the 100 originally employed.

B. In another experiment for analysis, 130 grs. dissolved as above, were
thrown down by carbonate of soda. 95 grs. of black oxide of mercury were
obtained, which are equivalent to 91·2 grs. of quicksilver; affording a
confirmation of the preceding result.

C. 130 grs. of fulminate were dissolved in strong muriatic acid, and the
solution was decomposed by crystals of proto-muriate of tin at a boiling
temperature. The mercury was precipitated in globules to such amount as
to verify the two preceding experiments.

Regarding fulminate of mercury as a bi-cyanate, that is, as a compound
of one atom or one equivalent prime of deutoxide of mercury, and two
primes of cyanic acid, we shall find its theoretical composition to be
as follows, hydrogen being the radix, or 1.

  2 Primes of Cyanic or fulminic Acid = 34 × 2 = 68     24
  1           Deutoxide of Mercury =            216     76
                                                ---    ---
                                                284    100

As these 284 parts of fulminate contain 200 of quicksilver, so 142 parts
of fulminate will contain 100 of quicksilver. Whence it appears, that
when only 130 parts of fulminate can be obtained in practice from 100 of
quicksilver, 8-1/2 parts of quicksilver out of the 100 are unproductive,
that is, are expended in the etherized gas, or left in the residuary
acidulous liquid. By the above experimental and theoretical analysis,
91·5 parts of quicksilver enter into the composition of 130 parts of
true crystalline fulminate. The complete accordance here exhibited
between theory and practice removes every shadow of doubt as to the
accuracy of the statements. 100 parts of fulminate consist of--

  Mercury }   70·4 }  Peroxide  76·0
  Oxygen  }    5·6 }
  Fulminic acid                 24
                               -----
                               100·0

_Question 3._ May the gas or vapour produced by the inflammation of the
fulminate of mercury, when combined with a portion of gunpowder, be
considered in its nature corrosive of iron or brass?

_Answer._ I have suggested to Mr. Lovell, of Waltham Abbey works, that
the fulminate may be probably diluted most advantageously with spirit
varnish made of a proper consistence by dissolving sandarach in alcohol.
When well mixed with this varnish, a small drop of the mixture will
suffice for priming each copper cap or disc; and as the spirit
evaporates immediately, the fulminate will be fixed to the copper beyond
the risk of shaking or washing away. On the Continent, tincture of
benjamin is used for the same purpose; but as that balsamic resin leaves
in combustion a voluminous coal, which sandarach does not, the latter,
which is the main constituent of spirit varnish, seems better adapted
for this purpose. It is sufficiently combustible, and may be yet made by
a due proportion, to soften the violence of the explosive mercury on the
nipple of the touch-hole. Fulminate prepared by my formula has no
corrosive influence whatsoever on iron or steel; and, therefore, if such
a medium of applying it, as I have now taken leave to suggest, should be
found to answer, all fears on the score of corrosion may for ever be set
at rest.

_Question 4._ How far is the mixture (of fulminate and gunpowder) liable
to be affected by the moisture of the atmosphere, or by the intrusion of
water; and will such an accident affect its inflammability when dried
again?

_Answer._ Well made fulminate, mixed with gunpowder and moistened,
undergoes no change, nor is it apt to get deteriorated by keeping any
length of time in a damp climate or a hazy atmosphere. Immersion in
water would be apt to wash the nitre out of the pulverine; but this
result would be prevented if the match or priming mixture were liquefied
or brought to the pasty consistence not with water, but spirit varnish.
Such detonating caps would be indestructible, and might be alternately
moistened and dried without injury.

_Question 5._ Is it at all probable that the composition would be
rendered more inflammable or dangerous of use, by the heat of tropical
climates?

_Answer._ No elevation of temperature of an atmospheric kind, compatible
with human existence, could cause spontaneous combustion of the
fulminating mercury, or the detonating matches made with it. In fact,
its explosive temperature is so high as 367° of Fahrenheit’s scale, and
no inferior heat will cause its detonation.

_Question 6._ Is the mercurial vapour or gas arising from the ignition
of a great number of primers, and combined with the smoke of gunpowder
in a confined space (as in the case of troops in close bodies, squares,
casemates, &c.) likely in its nature to be found prejudicial to human
health?

_Answer._ I have exploded in rapid succession of portions, 100 grains of
fulminate of mercury (equivalent to 300 or 400 primers), in a close
chamber of small dimensions, without experiencing the slightest
inconvenience at the period, or afterwards, though my head was
surrounded by the vapours all the time of the operation. These vapours
are, in fact, so heavy that they subside almost immediately. When the
fulminate mixed with pulverine is exploded in the primers by condensed
masses of troops, the mercury will cause no injury to their health, nor
one 100th part of the deleterious impression on weak lungs which the
gases of exploded gunpowder might by possibility inflict. These gases
are all, _theoretically_ speaking, noxious to respiration; such as
carbonic acid gas, azote, carburetted hydrogen, and sulphuretted
hydrogen, a deadly gas. Yet the soldier who should betray any fear of
gunpowder smoke would be an object of just ridicule.”

In the following September, I executed for the Board of Ordnance a set
of experiments complementary to those of the memoir, with the view of
ascertaining the best manner of protecting the fulminate when applied to
the copper caps, from being detached by carriage, or altered by keeping.
The following were my results and conclusions.

1. Fulminate of mercury moistened upon copper is speedily decomposed by
the superior affinity of the copper over mercury, for oxygen and
fulminic acid. Dryness is, therefore, essential to the preservation of
the fulminate; and hence charcoal, which is apt to become moist, should
not be introduced into percussion caps destined for distant service.

2. An alcoholic solution of sandarach, commonly called spirit varnish,
acts powerfully on copper, with the production of a green efflorescence,
which decomposes fulminate of mercury. Indeed, sandarach can decompose
the salts of copper. It is therefore ill adapted for attaching the
fulminate to copper caps.

3. An alcoholic solution of shell-lac acts on copper, though more feebly
than the sandarach.

4. A solution of mastic in spirits of turpentine, whether alone or mixed
with fulminate, has no action whatever on bright copper, but protects it
from being tarnished. Such a varnish is very cheap, dries readily,
adheres strongly, screens the fulminate from damp, and does not impair
or counteract its detonating powers. This, therefore, is in my opinion
the fittest medium for attaching the fulminate, and for softening the
force of its impulsion in any degree proportional to the thickness of
the varnish.”

Fulminate of mercury is obtained in white grains, or short needles, of a
silky lustre, which become gray upon exposure to light, and detonate
either by a blow or at a heat under 370° F.; with the disengagement of
azote, carbonic acid, as also of aqueous and mercurial vapours; to the
sudden formation of which gaseous products the report is due. It
detonates even in a moist condition; and when dry it explodes readily
when struck between two pieces of iron, less so between iron and bronze,
with more difficulty between marble and glass, or between two surfaces
of marble or glass. It is hardly possible to explode it by a blow with
iron upon lead; and impossible by striking it with iron upon wood. It
fulminates easily when rubbed between two wooden surfaces; less so
between two of marble, two of iron, or one of iron against one of wood
or marble. The larger its crystals, the more apt they are to explode. By
damping it with 5 per cent. of water, it becomes less fulminating; the
part of it struck still explodes with a proper blow, but will not kindle
the adjoining portion. Though moistened with 30 per cent. of water, it
will occasionally explode by trituration between a wooden muller and a
marble slab, but only to a small extent, and never with any danger to
the operator. When an ounce of it, laid upon the bottom of a cask, is
kindled, it strikes a round hole down through it, as if it had been
exposed to a four-pound shot, without splintering the wood. If a train
of fulminate of mercury be spread upon a piece of paper, covered with
some loose gunpowder, in exploding the former the latter will not be
kindled, but merely scattered. When gunpowder, however, is packed in a
cartridge, or otherwise, it may be certainly kindled by a percussion cap
of the fulminate, and more completely than by a priming of gunpowder.
8-1/2 parts of gunpowder exploded by a percussion cap, have an equal
projectile force as 10 exploded by a flint lock. If we add to this
economy in the charge of the barrel, the saving of the powder for
priming, the advantage in military service of the percussion system will
become conspicuous.

The French calculate that 1 kilogramme of mercury will furnish 1-1/4
kil. (2-1/2 lbs. nearly) of fulminate, which will be sufficient to
charge 40,000 percussion caps. For this purpose they grind the
crystalline salt along with 30 per cent. of water upon a marble table
with a wooden muller; mixing with every 10 parts of the fulminate 6 of
gunpowder. A consistent dough is thus obtained, which, being dried in
the air, is ready for introducing into the bottoms of the copper caps.
One quarter of a grain of the fulminate is said to be fully sufficient
for one priming.

Mr. Lovell, of the Royal Manufactory of Arms, has lately executed a
series of experiments upon priming powders. His trials, which occupied
nearly 18 months, were made for the purpose of ascertaining what is the
advantage in point of _force_ obtained by using percussion primes. He
had anticipated some extra energy would be imparted to the charge of
powder in the barrel, because he had repeatedly proved that a good
strong cap, exploded by itself on the nipple of the musquet, (without
any charge of gunpowder), will exert sufficient force upon the air
within the barrel to blow a candle out at a distance of 12 feet from the
muzzle. He concluded also that stopping the escape of fluid from the
vent, as is done by the cap, would have some effect, but he attributed
most to the quickness and energy with which the powder of the charge is
ignited by the vivid stream of flame, generated by the percussion prime.
The trials were made from one and the same barrel, having a percussion
lock on one side and a flint lock on the other. The balls were fired
against Austen’s recoiling target, a very delicate _plegometer_,
beginning with a charge of 150 grains (the present musquet charge), and
descending by 10 grains at a time (firing 30 rounds with each weight),
down to 50 grains. The machine marked the decrease of force at each
reduction in the charge very satisfactorily, and the result of the whole
average was that 8·84 parts of gunpowder fired by percussion are equal
to 10 parts fired by the flint.

To find out what sort of liberties might be taken with fulminate of
mercury in handling it, he placed 3 grains on an anvil, putting the end
of a steel punch gently on the top of it, and while so placed he covered
the fulminate over with a drachm of dry gunpowder. He then ignited the
fulminate by a blow on the punch with the hammer, but not a grain of the
gunpowder was lighted, though it was blown about in all directions. He
then placed a train of fulminate as thick as a quill, and about 3 feet
long, on a table, and covered it over entirely with gunpowder except
about an inch at one end; this he lighted with a hot iron, when the
whole train went off without blazing a grain of the gunpowder, which he
swept together and blew up afterwards with a match. He then took a tin
box containing 500 copper caps, made a hole in the top of the box, and
through this hole ignited one of the caps in the middle, by means of the
punch and hammer on the outside; only two other caps besides the one
struck exploded; no injury was sustained by the remainder, except being
discoloured. This he tried repeatedly, and always with the same kind of
result, never more than 3 or 4 caps exploding. He then made a steel
rammer red hot, and passed it through the hole in the box right in
amongst the caps, but it only ignited them where the hot iron came in
actual contact with the priming composition; when, however, he placed a
few grains of gunpowder loose among the caps, the hot iron lighted this,
and produced a flame that blew off the whole of them.

The same thing has been tried at Woolwich, where large packages of
percussion caps (some thousands) have been fired at with musquet balls,
and only a few of the caps actually hit by the ball exploded; but when
any cartridges were connected with the packages, the whole, caps and all
were blown up. The flame of the fulminate is therefore hazardous, but
being so very ethereal, it requires for making primes, an admixture of
some combustible matter, as a little gunpowder, to condense or modify
the flame.


FULMINIC ACID; (_Acide fulminique_, Fr.; _Knallsäure_, Germ.) is the
explosive constituent of the fulminating mercury of Howard, and the
fulminating silver of Brugnatelli, being generated by the reaction of
alcohol and the acid nitrates of these metals. It is a remarkable
chemical fact, that fulminic acid has exactly the same composition as
cyanic acid; though the salts of the latter possess no detonating
property, and afford, in their decomposition by an oxygen acid, ammonia
with carbonic acid; while those of the former afford ammonia and prussic
acid. All attempts to insulate fulminic acid have proved unsuccessful,
as it explodes with the slightest decomposing force. It consists, by
weight, of 2 primes of carbon, 1 of azote, and 1 of oxygen; or of two
volumes of carbonic acid, and one of azote. When two different bodies,
like the above, have the same composition, they are said to be
_isomeric_.


FUMIGATION, is the employment of fumes or vapours to purify articles of
apparel, and goods or apartments supposed to be imbued with some
infectious or contagious poison or fumes. The vapours of vinegar, the
fumes of burning sulphur, explosion of gunpowder, have been long
prescribed and practised, but they have in all probability little or no
efficacy. The diffusion of such powerful agents as chlorine gas,
muriatic acid gas, or nitric acid vapour, should alone be trusted to for
the destruction of morbific effluvia.


FUR; see PELTRY.

[Illustration: 481]


FURNACE OF ASSAY. Under ASSAY, I have referred to a furnace constructed
by Messrs. Anfrye and d’Arcet, which gives some peculiar facilities and
economy to the ancient process by fire. It had originally a small pair
of bellows attached to it, for raising the heat rapidly to the proper
vitrifying pitch. The furnace, 17-1/2 inches high, and 7-1/2 inches
wide, made of pottery or fine clay, is represented _fig._ 481.,
supported upon a table, having a pair of bellows beneath it. The
laboratory is at _b_, the blow-pipe of the bellows at _d_, with a
stop-cock, and the dome is surmounted by a chimney _a_, _c_, in whose
lower part there is an opening with a sliding door, for the introduction
of the charcoal fuel. The furnace is formed in three pieces; a dome, a
body, and an ash-pit. A pair of tongs, a stoking hook, and cupel, are
seen to the right hand, and the plan of the stone-ware grate, pierced
with conical holes, and a poker, are seen to the left. This grate suits
the furnace represented under ASSAY. The following are comparative
experiments made by means of this furnace:

  +--------+---------+---------+-----------+--------------+-----------+
  |Numbers.| Silver  |  Lead   |  Time of  |  Standards.  | Charcoal  |
  |        |employed.|employed.|   Assay.  |              |   used.   |
  +--------+---------+---------+-----------+--------------+-----------+
  |   1    |1 Grain. |4 Grains.|12 minutes.|947 millièmes.|173 Grains.|
  |   2    |   --    |   --    |11         |950           | 86        |
  |   3    |   --    |   --    |13         |949           | 93        |
  |   4    |   --    |   --    |10         |949           | 60        |
  +--------+---------+---------+-----------+--------------+-----------+

Each assay was therefore performed at an average in 11-1/2 minutes, and
not much more than a quarter of a pound of charcoal was used. An
experiment of verification in the ordinary assay furnace showed the
standard to be 949 thousandths.

This furnace becomes a very convenient one for melting small quantities
of metals in analyses, by removing the muffle, and closing the several
apertures with their appropriate stoppers. A small pedestal may be then
set in the middle of the grate, to support a crucible, which may be
introduced through the opening _h_. Coak may also be used as fuel,
either by itself or mixed with charcoal. For descriptions of various
furnaces, see ASSAY; BEER; COPPER; EVAPORATION; IRON; METALLURGY; ORES;
SILVER; TIN; &c.


FUSIBILITY. That property by which solids assume the fluid state.

Some chemists have asserted that fusion is simply a solution in caloric;
but this opinion includes too many yet undecided questions, to be
hastily adopted.

_Fusibility of Metals, as given by M. Thenard._

                                Centigr.
  1. Fusible below a  Mercury    -39°
  red heat.           Potassium  +58° } Gay Lussac and Thenard.
                      Sodium      90  }
                      Tin        210 }  Newton.
                      Bismuth    256 }
                      Lead       260    Biot.
                      Tellurium  A little less fusible than lead.--
                                        Klaproth.
                      Arsenic    Undetermined.
                      Zinc       370°   Brongniart.
                      Antimony   A little below a red heat.
                      Cadmium           Stromeyer.

                    Pyrometer of Wedgewood.

  2. Infusible below  Silver      20°   Kennedy.
  a red heat.         Copper      27 }  Wedgewood.
                      Gold        32 }
                      Cobalt     A little less difficult to melt than
                                 iron.
                      Iron      {130    Wedgewood.
                                {158    Sir G. M’Kenzie.
                      Manganese  160    Guyton.
                      Nickel            As manganese.--Richter.
                      Palladium  }
                      Molybdenum } Nearly infusible; and to be obtained
                      Uranium    } at a forge heat only in small
                      Tungsten   } buttons.
                      Chromium   }
                      Titanium  }
                      Cerium    }
                      Osmium    }  Infusible at the forge furnace.
                      Iridium   }  Fusible at the oxyhydrogen blowpipe.
                      Rhodium   }  See BLOWPIPE.
                      Platinum  }
                      Columbium }


FUSIBLE METAL. See ALLOY.


FUSTET. (_Fustec_, Fr.) The wood of the _rhus cotinus_, a fugitive
yellow dye.


FUSTIAN, is a species of coarse thick tweelled cotton, and is generally
dyed of an olive, leaden, or other dark colour. Besides the common
fustian, which is known by the name of pillow (probably pilaw), the
cotton stuffs called corduroy, velverett, velveteen, thicksett, used for
men’s wearing apparel, belong to the same fabric. The commonest kind is
merely a tweel of four, or sometimes five leaves, of a very close stout
texture, and very narrow, seldom exceeding 17 or 18 inches in breadth.
It is cut from the loom in half pieces, or ends as they are usually
termed, about 35 yards long, and after undergoing the subsequent
operations of dyeing, dressing, and folding, is ready for the market.

The draught and cording of common fustian is very simple, being
generally a regular or unbroken tweel of four or five leaves. Below are
specimens of a few different kinds, selected from those most general in
Lancashire.

The number of leaves of heddles are represented by the lines across the
paper, and the _cording_ by the cyphers in the little squares, those
which raise every leaf being distinguished by these marks, and those
which sink them left blank, as more particularly explained in the
article TEXTILE FABRIC.

Of velvet, there are properly only two kinds, that with a plain, and
that with a tweeled, or, as it is here called, a Genoa ground, or back.
When the material is silk, it is called velvet, when cotton, velveteen;
and this is the sole difference. In the same way a common tweeled cloth,
when composed of silk is called satin; when of cotton, fustian or jean;
of woollen, plaiding, serge, or kerseymere; and in the linen trade is
distinguished by a variety of names according to the quality or
fineness, or the place where the article is manufactured.

          No. 1.--Pillow Fustian.           No. 2.--Plain Velveret.
  -+-+-+-+-+------------------------------+-+-+-+-+-+--------------
   |0| | | |     4         5       1  §   | |0| | | |       3   1
  -+-+-+-+-+------------------------------+-+-+-+-+-+--------------
   | |0| | |       3     6       2    §   |0| | | | | 5
  -+-+-+-+-+------------------------------+-+-+-+-+-+--------------
   | | |0| | 6       2         3      §   |0| | |0|0|     0     2
  -+-+-+-+-+------------------------------+-+-+-+-+-+--------------
   | | | |0|   5       1     4        §   | | | |0| |   6     4
  -+-+-+-+-+------------------------------+-+-+-+-+-+--------------
      2 4 3 1                                4 6 2 3 1
                                                 5

Of the above, each contains four leaves of heddles or healds; that
represented by No. 1. is wrought by four treddles, and that which is
distinguished by No. 2. by five; the succession of inserting the threads
of warp into the heddles will be discovered by the figures between the
lines, and the order in which the treddles are to be successively
pressed down by the figures below.

      No. 3.--Double Jean.         No. 4.--Plain Thicksett.
  -+-+-+-+-+----------------------+-+-+-+-+-+----------------
   |0| | |0|       1          §   | |0| | | | 8
  -+-+-+-+-+----------------------+-+-+-+-+-+----------------
   |0| |0| |     2            §   | |0|0|0| |     6   4
  -+-+-+-+-+----------------------+-+-+-+-+-+----------------
   | |0|0| |   3              §   | | | |0| |       5     2
  -+-+-+-+-+----------------------+-+-+-+-+-+----------------
   | |0| |0| 4                §   |0| | |0|0|   7       3   1
  -+-+-+-+-+----------------------+-+-+-+-+-+----------------
    4 2 3 1                        4 6 2 3 1
                                       5   7

These, like the former, are wrought with leaves. No. 3. requires four,
and No. 4. five treddles. The succession of inserting the threads of
warp, and of working the treddles, are marked by the respective numbers
between and under the lines, as in the former example. Both are fabrics
of cloth in very general use and estimation as low priced articles.

    No. 5.--Best Thicksett.          No. 6.--Velvet Tuft.
  -+-+-+-+-+-+------------------+-+-+-+-+-+---------------------
   |0| | |0|0|       3   1   §  | |0| | | | 5   3   1
  -+-+-+-+-+-+------------------+-+-+-+-+-+---------------------
   | | | | |0|   5           §  | |0|0| | |             4   2
  -+-+-+-+-+-+------------------+-+-+-+-+-+---------------------
   | |0| | | |         2     §  |0| | |0|0|   4   2
  -+-+-+-+-+-+------------------+-+-+-+-+-+---------------------
   | |0|0| | | 6   4         §  | | | |0| |           5   3   1
  -+-+-+-+-+-+------------------+-+-+-+-+-+---------------------
    6 4 2 3 1                    6 4 2 3 1
        5

These are further specimens of what may be, and is, executed with four
leaves, and in both examples five treddles are used. With two other
specimens we shall conclude our examples of this description of work,
and shall then add a very few specimens of the more extensive kinds.

  No. 7.--Cord and Velveret.                No. 8.--Thicksett Cord.
  -+-+-+-+-+-+-----------------------------+-+-+-+-+-+-----------------
   | |0| | | |      3   1           3   1 §|0| | |0|0|        5   3   1
  -+-+-+-+-+-+-----------------------------+-+-+-+-+-+-----------------
   | |0|0| | |  5           7   5         §| |0| | | |          4   2
  -+-+-+-+-+-+-----------------------------+-+-+-+-+-+-----------------
   |0| | |0|0|6           8           2   §| | | | | |    9   7
  -+-+-+-+-+-+-----------------------------+-+-+-+-+-+-----------------
   | | | |0| |    4   2       6   4       §| |0|0| | | 10   8   6
  -+-+-+-+-+-+-----------------------------+-+-+-+-+-+-----------------
    4   2 3 1                               5 4 3 2 1
      6 5

In these the succession of drawing and working are marked like the
former. The next are examples of patterns wrought with six leaves. No.
9. has eight, and No. 10. five heddles.

      No. 9.--Double Corduroy.          No. 10.--Genoa Thicksett.
  -+-+-+-+-+--+--+--+-+-----------------+-+-+--+-+-+--------------
   | | | |0|  |0 |  |0|           1  §  | | |  |0|0|            1
  -+-+-+-+-+--+--+--+-+-----------------+-+-+--+-+-+--------------
   | |0| | |  |0 |  | |         2    §  | | | 0| |0|          2
  -+-+-+-+-+--+--+--+-+-----------------+-+-+--+-+-+--------------
   |0|0|0|0|0 |  |  | |       3      §  |0| | 0|0| |        3
  -+-+-+-+-+--+--+--+-+-----------------+-+-+--+-+-+--------------
   | | | |0|  |0 |  | |     4        §  | |0|  |0|0|     4
  -+-+-+-+-+--+--+--+-+-----------------+-+-+--+-+-+--------------
   | |0| | |  |  | 0| |   5          §  |0| | 0| |0|   5
  -+-+-+-+-+--+--+--+-+-----------------+-+-+--+-+-+--------------
   | |0| |0|  |  |  | | 6            §  | |0|  |0| | 6
  -+-+-+-+-+--+--+--+-+-----------------+-+-+--+-+-+--------------
    2 4 6 8 10 12  3 1                   4 2  5 3 1
                   7 5                   8 6 11 9 7
                  11 9                   1 2 10

In both these the warp is inserted into the heddles the same way. The
difference is entirely in the application of the cords, and in the
succession of pressing down the treddles. We now give four specimens of
the flushed and cut work, known by the name of velveteen. They are also
upon six leaves, and the difference is solely in the cording and in the
treading.

    No. 11.         Queen’s Velveteens.           No. 12.
  -+-+--+--+-+-+--+-----------------+--+--+--+-+-+-+-------------
   | | 0|  |0|0|  |           1  §  |  |  |  |0| |0|           1
  -+-+--+--+-+-+--+-----------------+--+--+--+-+-+-+-------------
   | |  | 0| |0|  |         2    §  |  |  | 0| |0|0|         2
  -+-+--+--+-+-+--+-----------------+--+--+--+-+-+-+-------------
   | |  | 0|0| |  |       3      §  |  |  |  |0|0| |       3
  -+-+--+--+-+-+--+-----------------+--+--+--+-+-+-+-------------
   | |  |  |0|0| 0|     4        §  |  | 0|  |0| |0|     4
  -+-+--+--+-+-+--+-----------------+--+--+--+-+-+-+-------------
   | |  | 0| |0|  |   5          §  |  |  |  | |0|0|   5
  -+-+--+--+-+-+--+-----------------+--+--+--+-+-+-+-------------
   |0|  | 0|0| |  | 6            §  | 0|  |  |0|0| | 6
  -+-+--+--+-+-+--+-----------------+--+--+--+-+-+-+-------------
    1  2 12 8 4  2                    2  4  3     1
    5  7         6                    6  8  7   5
    9 11        10                   10 12 11 9

  No. 13.--Plain Velveteen.      No. 14.--Genoa Velveteen.
  -+-+-+-+-+-+-----------------+--+-+-+--+--+-+-------------
   | | | | |0|           1  §  |  | |0| 0|  |0|           1
  -+-+-+-+-+-+-----------------+--+-+-+--+--+-+-------------
   |0| | |0| |         2    §  |  |0|0|  |  | |         2
  -+-+-+-+-+-+-----------------+--+-+-+--+--+-+-------------
   | | | | |0|       3      §  | 0|0| | 0|  | |       3
  -+-+-+-+-+-+-----------------+--+-+-+--+--+-+-------------
   | | |0|0| |     4        §  |  | |0| 0|  | |     4
  -+-+-+-+-+-+-----------------+--+-+-+--+--+-+-------------
   | | | | |0|   5          §  |  |0|0|  | 0| |   5
  -+-+-+-+-+-+-----------------+--+-+-+--+--+-+-------------
   | |0| |0| | 6            §  |  |0| | 0|  | | 6
  -+-+-+-+-+-+-----------------+--+-+-+--+--+-+-------------
    1 3 2 4 8                    2 4 8 12  3 1
    5 7 6                        6         7 5
                                10        11 9

The additional varieties of figure which might be given are almost
endless, but the limits of this article will not admit a further detail.
Those already given are the articles in most general use. The varieties
of fancy may be indulged to great extent, but it is universally found,
that the most simple patterns in every department of ornamental weaving,
are those which attract attention and command purchasers. We shall
therefore only add two examples of king’s cord or corduroy, two of Genoa
and common velvet, and two more of jean. These will be found below.

    No. 15.--King’s Cord.               No. 16.--Dutch Cord.
  -+-+-+-+-+-+-+---------------------+-+-+-+-+-+------------------
   | | | | |0|0|               1  §  | | |0| | |           4     1
  -+-+-+-+-+-+-+---------------------+-+-+-+-+-+------------------
   | | |0| | |0|             2    §  | |0| | |0|         5     2
  -+-+-+-+-+-+-+---------------------+-+-+-+-+-+------------------
   | | |0|0| | |   7       3      §  |0| | |0| |       6     3
  -+-+-+-+-+-+-+---------------------+-+-+-+-+-+------------------
   | | | |0|0| | 8       4        §  | |0|0| | |     7
  -+-+-+-+-+-+-+---------------------+-+-+-+-+-+------------------
   | |0| | |0|0|       5          §  |0| |0| |0|   8
  -+-+-+-+-+-+-+---------------------+-+-+-+-+-+------------------
   |0| |0| | | |     6            §  |0|0| |0|0| 9
  -+-+-+-+-+-+-+---------------------+-+-+-+-+-+------------------
    1 3 8 6 4 2                       6 4 2 3 1
    5 7                                   5

    No. 17.--Genoa Velvet.           No. 18.--Plain Velvet.
  -+--+-+-+--+--+-+-----------------+-+-+-+-+-+-------------
   |  | |0|  |  |0|           1  §  | | | | | |            1
  -+--+-+-+--+--+-+-----------------+-+-+-+-+-+-------------
   |  |0|0| 0|  | |         2    §  | | | | | |          2
  -+--+-+-+--+--+-+-----------------+-+-+-+-+-+-------------
   | 0|0| |  |  | |       3      §  | | | | | |        3
  -+--+-+-+--+--+-+-----------------+-+-+-+-+-+-------------
   |  | |0| 0|  | |     4        §  | | | | | |     4
  -+--+-+-+--+--+-+-----------------+-+-+-+-+-+-------------
   |  |0| | 0|  | |   5          §  | | | | | |   5
  -+--+-+-+--+--+-+-----------------+-+-+-+-+-+-------------
   |  |0| | 0|  | | 6            §  | | | | | | 6
  -+--+-+-+--+--+-+-----------------+-+-+-+-+-+-------------
     2 4 8 12  3 1                   1 3 4 2 8
     6         7 5                   7 5
    10        11 9

After the fustian cloth is taken from the loom-beam, it is carried to
the cutter, who rips up the surface-threads of weft, and produces
thereby a hairy-looking stuff.

Preparatory to its being cut, the cloth is spread evenly upon a table
about six feet long, upon each end of which a roller mounted with a
ratchet-wheel is fixed; the one to give off, and the other to wind up
the piece, in the above six-feet lengths.

The knife is a steel rod about two feet long, and three-eighths of an
inch square, having a square handle at the one end; the other end is
tapered away to a blade, as thin as paper. To prevent this point from
turning downwards and injuring the cloth, its under side is covered by a
guide which serves to stiffen it, as well as to prevent its lower edge
from cutting the fustian.

The operative (male or female) grasps the handle in the right hand, and
insinuating the projecting point of the guide under the weft, pushes the
knife smartly forward through the whole length of six feet, with a
certain dexterous movement of the shoulder and right side, balancing the
body meanwhile, like a fencer, upon the left foot. This process is
repeated upon every adhesive line of the weft.

The next process to which fustians are exposed is steeping in hot water,
to take out the dressing paste. They are then dried, reeled, and brushed
by a machine, &c. From twenty to thirty pieces, each eighty yards long,
may be brushed in an hour. The breadth of the cloth is twenty inches.
The maceration is performed by immersing the bundled pieces in tanks of
water, heated by waste steam; and the washing by means of a reel or
winch, kept revolving rapidly under the action of a stream of cold
water, for an hour or longer.

After being thus ripped up, it is taken to the brushing or teazling
machine, to make it shaggy.

This consists of a series of wooden rollers, turning freely upon iron
axles, and covered with tin-plate, rough with the burs of punched holes;
and blocks of wood, whose concave under surfaces are covered with
card-cloth or card-brushes, and which are made to traverse backwards and
forwards in the direction of the axes of the revolving rollers, during
the passage of the cloth over them.

After they are brushed in the machine, the goods are singed by passing
their cut surface over a cylinder of iron, laid in a horizontal
direction, and kept red hot by a flue. See SINGEING. They are now
brushed again by the machine, and once more passed over the singeing
surface. The brushing and singeing are repeated a third or even
occasionally a fourth time, till the cord acquires a smooth polished
appearance.

The goods are next steeped, washed, and bleached, by immersion in
solution of chloride of lime. They are then dyed by appropriate chemical
means. After which they are padded (imbued by the padding machine of the
calico printers) with a solution of glue, and passed over steam
cylinders to stiffen them.

Smooth fustians, when cropped or shorn before dyeing, are called
moleskins; but when shorn after being dyed, are called beaverteen, they
are both tweeled fabrics. Cantoon is a fustian with a fine cord visible
upon the one side, and a satiny surface of yarns running at right angles
to the cords upon the other side. The satiny side is sometimes smoothed
by singeing. The stuff is strong, and has a very fine aspect. Its price
is one shilling and sixpence a yard.

Common plain fustian, of a brown or drab colour, with satin top, is sold
as low as sevenpence a yard.

A fustian, with a small cord running in an oblique direction, has a very
agreeable appearance. It is called diagonal. Moleskin shorn, of a very
strong texture, and a drab dyed tint, is sold at 20_d_. per yard.

The weight of 90 yards of the narrow velveteen, in the green or
undressed state, is about 24 pounds. The goods made for the German,
Italian, and Russian markets are lighter, on account of the peculiarity
in the mode of levying the import duty in these countries.

Velveteens as they come from the loom, are sold wholesale by weight, and
average a price of 20_d._ per pound. They are usually woven with yarns
of Upland and Brazil cotton wool, spun together for the warp; or,
sometimes, New Orleans alone. The weft is usually Uplands, sometimes
mixed with East India cotton wools.

Trowser velveteens are woven 19 inches wide, if they are to be cut up;
if not, they are woven 30 inches, and called beaverteen.

Cutting or cropping fustians by hand is a very laborious and delicate
operation. The invention of an improved apparatus for effecting the same
end with automatic precision and despatch, was therefore an object of no
little interest to this peculiar manufacture of Manchester. An ingenious
machine, apparently well calculated for this purpose, was made the
subject of a patent by Messrs. William Wells and George Scholefield, of
Salford in November, 1834.


FUSTIC. (_Bois jaune_, Fr.; _Gelbholz_, Germ.) The _old_ fustic of the
English dyer, as the article fustet is their _yellow_ fustic. It is the
wood of the Morus tinctoria. It is light, not hard, and pale yellow with
orange veins; it contains two colouring matters, one resinous, and
another soluble in water. The latter resembles weld, but it has more of
an orange cast, and is not so lively.

Its decoctions in water are brightened by the addition of a little glue,
and more by curdled milk. This wood is rich in colour, and imparts
permanent dyes to woollen stuffs, when aided by proper mordants. It
unites well with the blue of the indigo vat, and Saxon blue, in
producing green of various shades. Alum, tartar, and solution of tin,
render its colour more vivid; sea salt and sulphate of iron deepen its
hue. From 5 to 6 parts of old fustic are sufficient to give a lemon
colour to 16 parts of cloth. The colour of weld is however purer and
less inclining to orange; but that of fustic is less affected by acids
than any other yellow dye. This wood is often employed with sulphate of
iron in producing olive and brownish tints, which agree well with its
dull yellow. For the same reason it is much used for dark greens.




G.


GABRONITE, is a yellowish stony substance, of a greasy lustre and spec.
gr. = 2·74; affording no water by calcination; fusible at the blowpipe
into an opaque glass; soluble in muriatic acid; solution affords hardly
any precipitate by oxalate of ammonia. This mineral is distinguished by
the large quantity of soda which it contains; its constituents
being,--silica, 54; alumina, 24; soda, 17·25; magnesia, 1·5; oxide of
iron, 1·25; water, 2. It belongs to the species Nepheline.


GADOLINITE; called also Yttrite and Ytterbite; is a mineral of a black,
brownish, or yellowish colour, granular, or compactly vitreous, and
conchoidal fracture; of spec. grav. 4·23? readily scratching glass;
fusible at the blowpipe into an opaque glass, sometimes with
intumescence. It affords, with acids, a solution that lets fall, with
caustic soda, a precipitate partly re-soluble in carbonate of ammonia.
It is remarkable for containing from 45 to 55 per cent. of the earth
Yttria; its remaining constituents being silica, 25·8; oxide of cerium,
17·92; oxide of iron, 11·43. This mineral is very rare, having been
hitherto found only in the neighbourhood of Fahlun and Ytterby, in
Sweden; its peculiar constituent was discovered by Professor Gadolin.


GALACTOMETER, or LACTOMETER, is an instrument to ascertain the quality
of milk; an article often sophisticated in various ways. Fresh milk,
rich in cream, has a less specific gravity, than the same milk after it
has been skimmed; and milk diluted with water becomes proportionably
lighter. Hence, when our purpose is to determine the quantity of cream,
the galactometer may consist merely of a long graduated glass tube
standing upright upon a sole. Having filled 100 measures with the recent
milk, we shall see, by the measures of cream thrown up, its value in
this respect. A delicate long-ranged glass hydrometer, graduated from
1·000 up to 1·060, affords the most convenient means of detecting the
degree of watery dilution, provided the absence of thickening materials
has been previously ascertained by filtration. Good fresh milk indicates
from 1·030 to 1·032; when the cream is removed, 1·035 to 1·037. When its
density is less than 1·028, we may infer it has been thinned with water.


GALBANUM, is a gum-resin, which occurs sometimes in yellow, shining
tears, easily agglutinated; of a strong durable smell; an acrid and
bitter taste; at other times in lumps. It exudes either spontaneously or
from incisions made into the stem of the _bubon galbanum_, a plant of
the family of _umbelliferæ_, which grows in Africa, particularly in
Ethiopia. It contains 67 of resin; 19·3 of gum; 6·4 of volatile oil and
water; 7·5 of woody fibres and other impurities; with traces of acid
malate of lime.


GALENA; (_Plomb sulfuré_, Fr.; _Bleiglanz_, Germ.;) is a metallic
looking substance of a lead-gray colour, which crystallizes in the
cubical system, and is susceptible of cleavages parallel to the faces of
the cube; spec. gr. 7·7592; cannot be cut; fusible at the blowpipe with
exhalation of sulphureous vapours; is easily reduced to metallic lead.
Nitric acid first dissolves it, and then throws down sulphate of lead in
a white precipitate; the solution affording with plates of zinc,
brilliant laminæ of lead (arbor Saturni.) It consists of sulphur, 13;
lead, 85; with a little iron, and sometimes a minute quantity of silver.
This is the richest ore of lead, and it occurs in almost every
geological formation, in veins, in masses, or in beds. It is almost
always accompanied by sulphuret of zinc, different salts of lead, heavy
spar, fluor spar, &c. Galena in powder, called Alquifoux, is employed as
a glaze for coarse stoneware.


GALIPOT, is a name of a white semi-solid viscid rosin found on
fir-trees; or an inferior sort of turpentine, poor in oil.


GALLATES; salts consisting of gallic acid combined with bases; the most
important being that with oxide of iron, constituting a principal part
of the black dye.


GALLIC ACID, is the peculiar acid extracted from gall-nuts; which see.


GALLIPOLI OIL, is a coarse olive oil, containing more or less mucilage;
imported from a sea port so named, of the province of Otranto, in the
kingdom of Naples.


GALL-NUTS, or GALLS; (_Noix de Galle_, Fr.; _Galläpfel_, Germ.;) are
excrescences found upon the loaves and leaf-stalks of a species of oak,
called _Quercus infectoria_, which grows in the Levant. They are
produced in consequence of the puncture of the female of the gall wasp,
(Cynips folii quercus), made in order to deposit her eggs; round which
the juice of the tree exudes, and dries in concentric portions. When the
insect gets fully formed, it eats through the nut, and flies off.

The Levant galls are of two different appearances and qualities; the
first are heavy, compact, imperforated, the insect having not been
sufficiently advanced to eat its way through the shell; prickly on the
surface; of a blackish or bluish green hue; about the size of a musket
ball. These are called _black_, blue, or Aleppo galls. The second are
light, spongy, pierced with one or more holes; smooth upon the surface,
of a pale grayish or reddish yellow colour, generally larger than the
first, and are called _white_ galls. Besides the galls of the Levant,
others come from Dalmatia, Illyria, Calabria, &c.; but they are of
inferior quality, being found upon the _Quercus Cerris_; they are
smaller, of a brownish colour, and of inferior value. The further south
the galls are grown, they are reckoned the better.

Galls consist principally of three substances; tannin or tannic acid;
yellow extractive; and gallic acid. Their decoction has a very
astringent and unpleasant bitter taste. The following are their
habitudes with various reagents:--

Litmus paper is powerfully reddened.

Stannous chloride (_protomuriate of tin_), produces an isabel yellow
precipitate.

Alum; a yellowish gray precipitate.

Acetate of lead; a thick yellowish white precipitate.

Acetate of copper; a chocolate brown precipitate.

Ferric sulphate (red sulphate of iron); a blue precipitate.

Sulphuric acid; a dirty yellowish precipitate.

Acetic acid brightens the muddy decoction.

The galls of the _Quercus Cerris_ and common oak (_Galles à l’épine_,
Fr.; _Knoppern_, Germ.) are of a dark-brown colour, prickly on the
surface, and irregular in shape and size. They are used chiefly for
tanning in Hungary, Dalmatia, and the southern provinces of the Austrian
states, where they abound.

Tannin or tannic acid is prepared as follows: Into a long narrow glass
adopter tube shut at its lower orifice with a cotton wick, a quantity of
pounded galls are put, and slightly pressed down. The tapering end of
the tube being inserted into a matrass or bottle, the vacant upper half
of the tube is filled with sulphuric ether, and then closed with a
ground-glass stopper. Next day there will be found in the bottle a
liquid in two distinct strata; of which the more limpid occupies the
upper part, and the other, of a syrupy consistence and amber colour, the
lower. More ether must be filtered through the galls, till the thicker
liquid ceases to augment. Both are now poured into a funnel, closed with
the finger, and after the dense liquor is settled at the bottom, it is
steadily run off into a capsule. This, after being washed repeatedly
with ether, is to be transferred into a stove chamber, or placed under
the receiver of an air pump to be evaporated. The residuary matter
swells up in a spongy crystalline form of considerable brilliancy,
sometimes colourless, but more frequently of a faintly yellowish hue.

This is pure tannin, which exists in galls to the amount of from 40 to
45 per cent. It is indispensable that the ether employed in the
preceding process be previously agitated with water, or that it contain
some water, because by using anhydrous ether, not a particle of tannin
will be obtained.

Tannic acid is a white or yellowish solid, inodorous, extremely
astringent, very soluble in water and alcohol, much less so in sulphuric
ether, and uncrystallizable. Its watery solution, out of contact of air,
undergoes no change; but if, in a very dilute state, it be left exposed
to the atmosphere, it loses gradually its transparency, and lets fall a
slightly grayish crystalline matter, consisting almost entirely of
gallic acid. For procuring this acid in a perfectly pure state, it is
merely necessary to treat that solution thus changed with animal
charcoal, and to filter it in a boiling state, through paper previously
washed with dilute muriatic acid. The gallic acid will fall down in
crystals as the liquid cools.

If the preceding experiment be made in a graduated glass tube containing
oxygen over mercury, this gas will be absorbed, and a corresponding
volume of carbonic acid gas will be disengaged. In this case the liquor
will appear in the course of a few weeks as if traversed with numerous
crystalline colourless needles of gallic acid.

Tannin or tannic acid consists of carbon 51·56; hydrogen 4·20; oxygen
44·24.

From the above facts it is obvious that gallic acid does not exist ready
formed in gall nuts, but that it is produced by the reaction of
atmospheric oxygen upon the tannin of these concretions.

Gallic acid is a solid, feebly acidulous and styptic to the taste,
inodorous, crystallizing in silky needles of the greatest whiteness;
soluble in about 100 times its weight of cold, and in a much smaller
quantity of boiling water; more soluble in alcohol than in water, but
little so in sulphuric ether.

Gallic acid does not decompose the salts of protoxide of iron, but it
forms, with the sulphate of the peroxide, a dark blue precipitate, much
less insoluble than the tannate of iron. Gallic acid takes the oxide
from the acetate and nitrate of lead, and throws down a white gallate
unchangeable in the air, when it is mixed with that acetate and nitrate.
It occasions no precipitate in solutions of gelatine (isinglass or
glue), by which criterion its freedom from tannin is verified.

Gallic acid occurs but seldom in nature; and always united to brucine,
veratrine, or lime. Its constituents are, carbon 49·89; hydrogen 3·49;
oxygen 46·62. In the crystalline state it contains one atom of water,
which it loses by drying.

Scheele obtained gallic acid by infusing pounded galls for 3 or 4 days
in 8 times their weight of water, and exposing the infusion to the air,
in a vessel covered loosely with paper. At the end of two months, the
liquor had almost all evaporated, leaving some mouldiness mixed with a
crystalline precipitate. The former being removed, the deposit was
squeezed in a linen cloth, and then treated with boiling water. The
solution being gradually evaporated, yielded crystals of gallic acid,
granular or star-like, of a grayish colour. These crystals might be
whitened by boiling their solution along with a little animal charcoal.
About one fifth of gallic acid may be obtained by Scheele’s process from
good gall-nuts.

From a decoction of 500 parts of galls, Sir H. Davy obtained 185 parts
of solid extract; which consisted of 130 parts of tannin; 31 parts of
gallic acid with extractive; 13 parts of mucilage; 12 parts of lime and
salts. Hence gall-nuts would seem to contain, by this statement, more
than two-thirds of their weight of tannin. This result is now seen, from
the above experiments of Pelouze, to have been incorrect, in consequence
of the admixture of yellow extractive in Davy’s tannin.

The uses of galls in many processes of dyeing, and in making black ink,
are detailed under their respective heads.


GALL OF ANIMALS, or OX-GALL, _purification of_. Painters in water
colours, scourers of clothes, and many others employ ox-gall or bile,
but when it is not purified, it is apt to do harm from the greenness of
its own tint. It becomes therefore an important object to clarify it,
and to make it limpid and transparent like water. The following process
has been given for that purpose. Take the gall of newly killed oxen, and
after having allowed it to settle for 12 or 15 hours in a basin, pour
the supernatant liquor off the sediment into an evaporating dish of
stone ware, and expose it to a boiling heat in a water bath, till it is
somewhat thick. Then spread it upon a dish, and place it before a fire
till it becomes nearly dry. In this state it may be kept for years in
jelly pots covered with paper, without undergoing any alteration. When
it is to be used, a piece of it of the size of a pea is to be dissolved
in a table spoonful of water.

Another and probably a better mode of purifying ox-gall is the
following. To a pint of the gall boiled and skimmed, add one ounce of
fine alum in powder, and leave the mixture on the fire till the alum be
dissolved. When cooled, pour into a bottle, which is to be loosely
corked. Now take a like quantity of gall also boiled and skimmed, add an
ounce of common salt to it, and dissolve with heat; put it when cold
into a bottle, which is likewise to be loosely corked. Either of these
preparations may be kept for several years without their emitting a bad
smell. After remaining three months, at a moderate temperature, they
deposit a thick sediment, and become clearer, and fit for ordinary uses,
but not for artists in water colours and miniatures, on account of their
yellowish-green colour. To obviate this inconvenience, each of the above
liquors is to be decanted apart, after they have become perfectly
settled, and the clear portion of both mixed together in equal parts.
The yellow colouring matter still retained by the mixture coagulates
immediately and precipitates, leaving the ox-gall perfectly purified and
colourless. If wished to be still finer, it may be passed through
filtering paper; but it becomes clearer with age, and never acquires a
disagreeable smell, nor loses any of its good qualities.

Clarified ox-gall combines readily with colouring matters or pigments,
and gives them solidity either by being mixed with or passed over them
upon paper. It increases the brilliancy and the durability of
ultramarine, carmine, green, and in general of all delicate colours,
whilst it contributes to make them spread more evenly upon the paper,
ivory, &c. When mixed with gum Arabic, it thickens the colours without
communicating to them a disagreeable glistering appearance; it prevents
the gum from cracking, and fixes the colours so well that others may be
applied over them without degradation. Along with lamp black and gum, it
forms a good imitation of China ink. When a coat of ox-gall is put upon
drawings made with black lead or crayons, the lines can no longer be
effaced, but may be painted over safely with a variety of colours
previously mixed up with the same ox-gall.

Miniature painters find a great advantage in employing it; by passing it
over ivory, it removes completely the unctuous matter from its surface;
and when ground with the colours, it makes them spread with the greatest
ease, and renders them fast.

It serves also for transparencies. It is first passed over the varnished
or oiled paper, and is allowed to dry. The colours mixed with the gall
are then applied, and cannot afterwards be removed by any means.

It is adapted finally for taking out spots of grease and oil.


GALL OF GLASS, called also sandiver, is the neutral salt skimmed off the
surface of melted crown glass; which, if allowed to remain too long, is
apt to be reabsorbed in part, and to injure the quality of the _metal_,
as the workmen call it.


GALVANIZED IRON, is the somewhat fantastic name newly given in France to
iron tinned by a peculiar patent process, whereby it resists the rusting
influence of damp air, and even moisture, much longer than ordinary tin
plate. The following is the prescribed process. Clean the surface of the
iron perfectly by the joint action of dilute acid and friction, plunge
it into a bath of melted zinc, and stir it about till it be alloyed
superficially with this metal; then take it out, and immerse it in a
bath of tin, such as is used for making tin plate. The tin forms an
exterior coat of alloy. When the metal thus prepared is exposed to
humidity, the zinc is said to oxidize slowly by a galvanic action, and
to protect the iron from rusting within it, whereby the outer tinned
surface remains for a long period perfectly white, in circumstances
under which iron tinned in the usual way would have been superficially
browned and corroded with rust.


GAMBOGE; (_Gomme Gutte_, Fr.; _Gutti_, Germ.) is a gum resin, concreted
in the air, from the milky juice which exudes from several trees. The
_gambogia gutta_, a tree which grows wild upon the coasts of Ceylon and
Malabar, produces the coarsest kind of gamboge; the _guttaefera vera_
(_Stalagmites cambogioides_) of Ceylon and Siam affords the best. It
comes to us in cylindrical lumps, which are outwardly brown yellow, but
reddish yellow within, as also in cakes; it is opaque, easily reducible
to powder, of specific gravity 1·207, scentless, and nearly devoid of
taste, but leaves an acrid feeling in the throat. Its powder and watery
emulsion are yellow. It consists of 80 parts of a hyacinth red resin,
soluble in alcohol; and 20 parts of gum; but by another analysis, of 89
of resin, and 10·5 of gum. Gamboge is used as a pigment, and in
miniature painting, to tinge gold varnish; in medicine as a powerful
purge. It should never be employed by confectioners to colour their
_liqueurs_, as they sometimes do.


GANGUE. A word derived from the German _gang_, a vein or channel. It
signifies the mineral substance which either encloses or usually
accompanies any metallic ore in the vein. Quartz, lamellar carbonate of
lime, sulphate of baryta, sulphate and fluate of lime, generally form
the gangues; but a great many other substances become such when they
predominate in a vein. In metallurgic works the first thing is to break
the mixed ore into small pieces, in order to separate the valuable from
the useless parts, by processes called stamping, picking, sorting. See
METALLURGY and MINES.


GARNET (_Grenat_, Fr.; _Granat_, Germ.); is a vitreous mineral of the
cubic system, of which the predominating forms are the rhomboidal
dodecahedron and the trapœzohedron; specific gravity varying from 3·35
to 4·24; fusible at the blowpipe. Its constituents are, silica, 42;
alumina, 20·0; lime, 34·0; protoxide of iron, 4. Garnets are usually
disseminated, and occur in all the primitive strata from gneiss to clay
slate. The finer varieties, noble garnet or Almandine, and the reddish
varieties of Grossulaire (Essonite), are employed in jewellery; the
first are called the Syrian or oriental; the others, hyacinth. In some
parts of Germany garnets are so abundant as to be used as fluxes to some
iron ores; in others, the garnet gravel is washed, pounded, and employed
as a substitute for emery. The garnets of Pegu are most highly valued.
Factitious garnets may be made by the following composition:--Purest
white glass, 2 ounces; glass of antimony, 1 ounce; powder of cassius, 1
grain; manganese, 1 grain.


GAS (Eng. and Fr.; _Gaz_, Germ.); is the generic name of all those
elastic fluids which are permanent under a considerable pressure, and at
the temperature of zero of Fahrenheit. In many of them, however, by the
joint influence of excessive cold and pressure, the repulsive state of
the particles may be balanced or subverted, so as to transform the
elastic gas into a liquid or a solid. For this most interesting
discovery, we are indebted to the fine genius of Mr. Faraday.

The following table exhibits the temperatures and pressures at which
certain gases are liquefied.

  +---------------------+--------------------------+-------------------+
  |                     |     Becomes liquid       |    Calculated     |
  |  Name of the gas.   +------+-------------------+  boiling point;   |
  |                     |  At  |Under a pressure of|Barom. = 30 inches.|
  +---------------------+------+-------------------+-------------------+
  |Sulphurous acid      |59° F.|   3 atmospheres.  |     -   4° Fahr.  |
  |Chlorine             |60    |   4               |     -  22         |
  |Ammonia              |50    |   6·5             |     -  64         |
  |Sulphuretted hydrogen|50    |  17               |     - 142         |
  |Carbonic acid        |32    |  36               |     - 229         |
  |Hydrochloric or      |      |                   |                   |
  |muriatic acid        |50    |  50               |     - 249         |
  |Deutoxide of azote   |45    |  50               |     - 254         |
  +---------------------+------+-------------------+-------------------+

Liquid carbonic acid becomes solidified, into a snowy-looking substance,
by its own rapid evaporation. Oxygen, hydrogen, and azote, have hitherto
resisted all attempts to divest them of their elastic form. For this
purpose, it is probable that a condensing force equal to that of 650
atmospheres, will be required.

The volume of any gas is, generally speaking, inversely as the pressure
to which it is exposed; thus, under a double pressure its bulk becomes
one-half; under a triple pressure, one-third; and so on. For the change
of volume in gaseous bodies by heat, see EXPANSION.

Ammonia, carbonic acid, carburetted hydrogen, chlorine, muriatic acid,
sulphurous acid, sulphuretted hydrogen, are the gases of most direct
interest in the arts and manufactures. Their detailed examination
belongs to a work on chemistry.


GAS-LIGHT. (_Eclairage par gas_, Fr.; _Gaslicht_, Germ.) Dr. Clayton
demonstrated, by numerous experiments in 1737 and 1738, that bituminous
pit-coal, subjected to a red heat in close vessels, afforded a great
deal of an air similar to the fire-damp of mines, but which burned with
a brighter flame. It does not appear that this species of factitious air
was ever produced from pit-coal for the purpose of artificial
illumination till 1792, when Mr. William Murdoch, engineer to Messrs.
Bolton and Watt, employed coal gas for lighting his house and offices,
at Redruth in Cornwall. The gas was generated in an iron retort, whence
it was received in a gasometer, distributed in different situations by
pipes, and finally burned at small apertures which could be opened and
stopped at pleasure. He moreover made this light movable, by confining
the gas in portable tin-plate vessels, and burning it wherever he
pleased. Between this period and 1802, Mr. Murdoch continued at
intervals to make similar experiments; and upon occasion of the national
illumination in the spring of the latter year, at the peace of Amiens,
he lighted up part of the Soho manufactory with a public display of gas
lights.

The earliest application of this artificial light, on a large systematic
scale, was made at Manchester; where an apparatus for lighting the great
cotton mills of Messrs. Philips and Lee, was fitted up in 1804 and 1805,
under the direction of Mr. Murdoch. A quantity of light, nearly equal to
3000 candles, was produced and distributed in this building. This
splendid pattern has been since followed very generally in Great
Britain, and more or less in many parts of the continents of Europe and
America. By the year 1822, gas-lighting in London had become the
business of many public companies. At the Peter-street station, for
example, 300 retorts had been erected, supplying 15 gasometers, having
each an average capacity of 20·626 cubic feet, but, being never quite
filled, their total contents in gas might be estimated at 309,385 cubic
feet. The extent of main pipes of distribution belonging to this station
was then about 57 miles, with two separate mains in some of the streets.
The product of gas was from 10,000 to 12,000 cubic feet from a chaldron
of coals. The annual consumption of coals was therefore altogether 9282
chaldrons, affording 11,384,000 cubic feet of gas, allowing 153 retorts
to be in constant daily action, upon an average of the year; and
illuminating 10,660 private lamps, 2248 street lamps, and 3894 theatre
lamps.

At the Brick-lane works, 371 retorts were fixed in 1822, 133 being
worked on an average of summer and winter. There were 12 gasometers,
charged with an average quantity of gas amounting to 197,214 cubic feet.
Of coals, 8060 chaldrons were annually consumed; 96,720,000 cubic feet
of gas were generated; for the supply of 1978 public lamps, and 7366
private ones, connected with main pipes 40 miles long.

At the Curtain-road gas establishment, there were 240 retorts; but the
greatest number worked in 1821 was only 80, and the lowest 21. The six
gasometers had an average contents of 90,467 cubic feet. Of coals, 3336
chaldrons were annually consumed, yielding 40,040,000 cubic feet of gas,
that supplied 3860 private lamps, and 629 public ones, by means of mains
25 miles long. The above three stations belonged to the London Gas Light
and Coke Company.

The City of London Gas Light Company, Dorset-street, had built up 230
retorts, and 6 gasometers, while two were preparing; having a total
capacity of 181,282 cubic feet. Of private lamps 5423 were lighted, and
2413 public ones, from mains extending 50 miles. The quantity of coals
carbonized amounted to 8840 chaldrons; producing 106,080,000 cubic feet
of gas.

The South London Gas Light and Coke Company had mounted at Bankside 143
retorts, with 3 gasometers; the contents of the whole being 41,110 cubic
feet, connected with mains from 30 to 40 miles long. At their other
station, in Wellington-street, 3 large gasometers were then erecting,
with a capacity of 73,565 cubic feet, which were to be supplied with gas
from Bankside, till retorts were mounted for them.

The Imperial Gas Light and Coke Company had at that time 6 gasometers in
progress at their Hackney station.

In 1822 there were thus four great companies, having in all 47
gasometers at work, capable of containing 917,940 cubic feet of gas,
supplied by 1315 retorts, which generated per annum upwards of
397,000,000 cubic feet of gas, by which 61,203 private lamps, and 7268
public or street lamps, were lighted in the metropolis. Besides these
public companies, there were likewise several private ones.

1. _Of the generation of illuminating gases._--Pure hydrogen gas burns
with too feeble a flame to be employed for illumination. But carburetted
hydrogen having the property of precipitating its carbon in the act of
burning, its solid particles become incandescent, and diffuse a vivid
light. The more carbon it contains, the more brightly does it burn. This
gas exists in two distinct states of combination. In the first, two
measures of hydrogen gas are combined with one measure of the vapour of
carbon, forming together one measure whose specific gravity is of course
the sum of the weights of the constituents, or 0·559; atmospherical air
being 1·000. This is the gas which is found in mines, and is also
evolved in ditches from decomposing vegetable matter. In the second, two
measures of hydrogen gas are combined with two of gaseous carbon,
forming also one volume or measure whose weight or specific gravity is
0·985. This was at one time called the olefiant gas, because when mixed
with chlorine an oily looking compound was produced. It may be called as
well oil gas, because it is generated in considerable quantities by the
igneous decomposition of oil. Thus the olefiant gas contains in the same
volume double the quantity of carbon of common carburetted hydrogen, and
it burns with a proportionably brighter flame. The gaseous oxide of
carbon, as well as sulphuretted hydrogen gas, burns with a feeble blue
light, but the latter produces in combustion sulphurous acid, an
offensive and noxious gas.

By dry distillation or carbonization in close vessels, all bodies of
vegetable and animal origin disengage carburetted hydrogen gas; even
charcoal when placed in ignition in contact with steam, by decomposing
the water, produces abundance of carbonic acid, carburetted hydrogen,
hydrogen, and carbonic oxide. After separating the carbonic acid with
lime water, that mixed gas contains in 100 measures, 20 of carburetted
hydrogen; the rest being hydrogen and carbonic oxide, so that the
gaseous mixture cannot be used for illumination. The best substances for
furnishing a gas rich in luminifereous materials are, pitcoal,
especially the cannel coal, resin, oil, fats of all kinds, tar, wax, &c.
In some cases the gases evolved during the igneous decomposition of
bones and other animal matters for the production of ammonia, may be
employed for procuring light, but they are apt to emit a fetid odour.

When coals are heated in a cast-iron retort to ignition, the progress of
decomposition is as follows. First, and before the retort becomes red
hot, steam issues along with the atmospheric air. When the retort begins
to redden, tar distils in considerable quantity with some combustible
gas, of which hydrogen mixed with ammoniacal gas forms a part. The
evolution of gas increases as the retort becomes hotter, with a
continual production of tar and ammoniacal liquor as well as sulphurous
acid from the pyrites of the coal, which unites with the ammonia. When
the retort has come to a bright cherry red heat, the disengagement of
gas is most active. By and bye the gaseous production diminishes, and
eventually ceases entirely, although the heat be increased. In the
retort a quantity of carbonized coal or coke remains, while tar is found
at the bottom of the receiver, covered with the ammoniacal liquor, and
combined with carbonic and sulphurous acids, and sulphuretted hydrogen.

If during this distillation, the combustible gas be collected and
examined at the several stages of the process, it is found to differ
extremely in its luminiferous powers. That which comes off before the
retort has acquired its proper temperature, gives a feeble light, and
resembles the gas obtained by the ignition of moist charcoal, consisting
chiefly of hydrogen. That evolved when the retort has just acquired
throughout a vivid red heat, is the best of all, consisting chiefly of
bicarburetted hydrogen or olefiant gas. From good coal, it consists, for
example in 100 measures, of 13 of olefiant gas, 82·5 of carburetted
hydrogen, 3·2 carbonic oxide, 1·3 azote; the mixture having a specific
gravity of 0·650. At a later period, as after 5 hours, it contains 7
measures of olefiant gas, 56 of carburetted hydrogen, 11 of carbonic
oxide, 21·3 of hydrogen, 4·7 of azote; the specific gravity of the whole
being 0·500. Towards the end of the operation, as after 10 hours, it
contains twenty measures of carburetted hydrogen, 10 of carbonic oxide,
60 of hydrogen, 10 of azote, with a specific gravity of only 0·345. The
hydrogen becomes sulphuretted hydrogen, if there be much pyritous matter
in the coal. The larger proportion of the gas is disengaged during the
first hour, amounting to about one fifth of the whole; in the three
following hours the disengagement is tolerably uniform, constituting in
all fifty-four hundredths; in the sixth hour, it is one tenth; in the
seventh and eighth hours, sixteen hundredths.

From these observations are derived the rules for the production of a
good light gas from coals. They show that the distillation should
commence with a retort previously heated to a cherry red, since thereby
good gas is immediately produced, and a portion of the tar is also
converted into gas, instead of being simply distilled over into the
condenser pit; that this heat should be steadily continued during the
whole operation, from 5 to 8 hours; that it should not be increased,
especially towards the end, for fear of generating carbonic oxide and
hydrogen gases, as well as of injuring the retort when the cooling
agency of gasefication has become feeble; and that the operation should
be stopped some time before gas ceases to come over, lest gases with
feeble illuminating power should impoverish the contents of the
gasometer. Upon the average, a pound of good coal affords four cubic
feet of gas, or a chaldron = 26 cwt. London measure, affords from 12,000
to 15,000 cubic feet, according to the form of the retort, and the
manner of firing it.

When oil, fats, rosin, tar, &c. are employed for the production of a
light gas, it is not sufficient to introduce these substances into the
retorts, and to heat them, as is done with coals. In this case, the
greater part of them would distil over in the state of volatile oils,
and very little gas be generated, only as much as corresponded to the
quantity of fat, &c. in immediate contact with the retort. It becomes
therefore necessary to fill the retorts with pieces of brick or coke;
and to keep them in ignition, while the oil, &c. is slowly introduced
into their interior. The fats instantly assume the vaporous state, and
thus coming into contact upon an extensive surface with the ignited
bricks, are decomposed into combustible gases. A small portion of
carbonaceous matter remains in the retort, while much olefiant gas is
formed, possessing a superior illuminating power to common coal gas, and
entirely free from sulphureous impregnation. The best oil gas is
generated at a dull red, a heat much below what is requisite for the
decomposition of coal. A more intense heat would indeed produce a
greater volume of gas, but of a poorer quality, because the olefiant gas
thereby deposits one half of its carbon, and is converted into common
carburetted hydrogen. Oil affords at a lively red heat, gases which
contain in 100 measures, 19 of olefiant gas, 32·4 of carburetted
hydrogen, 12·2 of carbonic oxide gas, 32·4 of hydrogen, and 4 of azote;
the mean specific gravity being only 0·590. At a more moderate
temperature it yields 22·5 of the olefiant, 50·3 carburetted hydrogen,
15·5 carbonic oxide, 7·7 hydrogen, and 4 azote, with a specific gravity
of 0·758. It contains when generated by dull ignition, as is usual in
works on the manufacturing scale, in 100 parts, from 38 to 40 of
olefiant gas, and besides the carburetted hydrogen, a few per cents. of
carbonic oxide and azote, with a specific gravity of 0·900, and even
upwards. One pound of oil or fluid fat affords 15 cubic feet of gas; of
tar affords about 12 cubic feet; of rosin or pitch, 10 cubic feet.

When the oil gas is compressed by a force of from 15 to 20 atmospheres,
as was the practice of the Portable Gas Company, about one fifth of the
volume of the gas becomes liquefied into an oily, very volatile fluid,
having the specific gravity 0·821. It is a mixture of three fluids
(consisting of carburetted hydrogen), of different degrees of
volatility. The most volatile of these boils even under 32° F. Some of
the vapour of this gas-oil is mixed with the olefiant gas in the general
products of decomposition; in consequence of which they are sometimes
richer in carbon than even olefiant gas, and have a higher illuminating
power. Oil gas contains about 22 per cent. and coal gas about 3-1/4 per
cent. of this oily vapour. In the estimations of the composition of the
gases given above, this vapour is included under olefiant gas. This
vapour combines readily with sulphuric acid, and is thus precipitated
from the gaseous mixture. The amount of olefiant gas is shown, by adding
to the gas, contained over water, one half of its volume of chlorine,
which, in the course of an hour or two, condenses the olefiant gas into
an oily looking liquid (chloride of hydrocarbon.) After the mixture, the
gases must be screened from the light, otherwise the common carburetted
hydrogen would also combine with the chlorine, while water and carbonic
acid would make their appearance.

The oil employed for affording gas is the crudest and cheapest that can
be bought; even the blubber and sediment of whale oil are employed with
advantage. After all, however, coal is so much cheaper, and the gas
produced from it is now so well purified, that oil and rosin are very
little used in gas apparatus.

_Apparatus for Coal Gas._--Coal gas, as it issues from the retort,
cannot be directly employed for illumination; for it contains vapours of
tar and coal oil, as also steam impregnated with the carbonate,
sulphite, and hydrosulphuret of ammonia. These vapours would readily
condense in the pipes through which the gas must be distributed, and
would produce obstructions; they must therefore be so far removed by
previous cooling, as to be liable to occasion no troublesome
condensation at ordinary temperatures. The crude coal gas contains
moreover sulphuretted hydrogen, whose combustion for light would exhale
an offensive sulphureous odour, that ought to be got rid of as much as
possible. Carbonic acid and carbonic oxide gases, generated at first
from the decomposition of the steam by the ignited coal, enfeeble the
illuminating power of the gas, and should be removed. The disengagement
of gas in the retorts is never uniform, but varies with the degree of
heat to which they are exposed; for which reason the gas must be
received in a gasometer, where it may experience uniform pressure, and
be discharged uniformly into the pipes of distribution, in order to
ensure a steady discharge of gas, and uniform intensity of light in the
burners. A coal gas apparatus ought therefore to be so constructed as
not only to generate the gas itself, but to fulfil the above
conditions.

In _fig._ 482., such an apparatus is represented, where the various
parts are shown connected with each other, in section.

[Illustration: 482]

A is the furnace with its set of cylindrical or elliptical retorts, five
in number. From each of these retorts, a tube _b_ proceeds
perpendicularly upwards, and then by a curve or saddle-tube, it turns
downwards, where it enters a long horizontal cylinder under B, shut at
each end with a screw cap, and descends to beneath its middle, so as to
dip about an inch into the water contained in it. From one end of this
cylinder the tube _d_ passes downwards, to connect itself with a
horizontal tube which enters into the _tar pit_ or _cistern_ C, by means
of the vertical branch _f_. This branch reaches to near the bottom of
the cylindrical vessel, which sits on the sole of the tar cistern. From
the other side of the vertical branch _f_, the main pipe proceeds to the
condenser D, and thence by the pipe _l_, into the purifier E; from which
the gas is immediately transmitted by the pipe _p_ into the gasometer F.

The operation proceeds in the following way:--As soon as gas begins to
be disengaged from the ignited retort, tar and ammoniacal liquor are
deposited in the cylindrical receiver B, and fill it up till the
superfluity runs over by the pipe _d_, the level being constantly
preserved at the line shown in the figure. By the same tarry liquid, the
orifices of the several pipes _b_, issuing from the retorts, are closed;
whereby the gas in the pipe _d_ has its communication cut off with the
gas in the retorts. Hence if one of the retorts be opened and emptied,
it remains shut off from the rest of the apparatus. This insulation of
the several retorts is the function of the pipe under B, and therefore
the recurved tube _b_ must be dipped as far under the surface of the
tarry liquid, as to be in equilibrio with the pressure of the gas upon
the water in the purifier. The tube _b_ is closed at top with a screw
cap, which can be taken off at pleasure, to permit the interior to be
cleansed.

Both by the overflow from the receiver-pipe B, and by subsequent
condensation in the tube _d_, tar and ammoniacal liquor collect
progressively in the cistern or pit under C, by which mingled liquids
the lower orifice of the vertical tube _f_ is closed, so that the gas
cannot escape into the empty space of this cistern. These liquids flow
over the edges of the inner vessel when it is full, and may, from time
to time, be drawn off by the stopcock at the bottom of the cistern.

Though the gas has, in its progress hitherto, deposited a good deal of
its tarry and ammoniacal vapours, yet, in consequence of its high
temperature, it still retains a considerable portion of them, which must
be immediately abstracted, otherwise the tar would pollute the lime in
the vessel E, and interfere with its purification. On this account the
gas should, at this period of the process, be cooled as much as
possible, in order to condense these vapours, and to favour the action
of the lime in the purifier E, upon the sulphuretted hydrogen, which is
more energetic the lower the temperature of the gas. The coal gas
passes, therefore, from the tube _f_ into the tube _h_ of the condenser
D, which is placed in an iron chest _g_ filled with water, and it
deposits more tar and ammoniacal liquor in the under part of the cistern
at _t_, _t_. When these liquids have risen to a certain level, they
overflow into the tar-pit, as shown in the figure, to be drawn off by
the stopcock as occasion may require.

The refrigerated gas is now conducted into the purifier E, which is
filled with milk of lime, made by mixing one part of slaked lime with 25
parts of water. The gas, as it enters by the pipe _l_, depresses the
water in the wide cylinder _n_, thence passes under the perforated disc
in the under part of that cylinder, and rising up through innumerable
small holes is distributed throughout the lime liquid in the vessel _m_.
By contact with the lime on this extended surface, the gas is stripped
of its sulphuretted hydrogen and carbonic acid, which are condensed into
the hydro-sulphuret and carbonate of lime; it now enters the gasometer F
in a purified state, through the pipe _p t_, and occupies the space _q_.
The gasometer, pressing with a small unbalanced force over the
counterweight _s_, expels it through the main _u u_, in communication
with the pipes of distribution through the buildings or streets to be
illuminated.

The parts A B C D E and F, of which this apparatus consists, are
essential constituents of every good coal-gas work. Their construction
rests upon peculiar principles, is susceptible of certain modifications,
and therefore deserves to be considered in detail.

_The Retorts._--These are generally made of cast iron, though they have
occasionally been made of baked clay, like common earthenware retorts.
The original form was a cylinder, which was changed to an ellipse, with
the long axis in a horizontal direction, then into the shape of the
letter D with the straight line undermost, and lastly into a
semi-cylinder, with its horizontal diameter 22 inches, and its vertical
varying from 9 to 12. The kidney form was at one time preferred, but it
has been little used of late.

[Illustration: 483]

The form of retort represented in _fig._ 483. has been found to yield
the largest quantity of good gas in the shortest time, and with the
least quantity of firing. The length is 7-1/2, and the transverse area,
from one foot to a foot and a half square. The arrows show the direction
of the flame and draught in this excellent bench of retorts, as mounted
by Messrs. Barlow.

The charge of coals is most conveniently introduced in a tray of sheet
iron, made somewhat like a grocer’s scoop, adapted to the size of the
retort, which is pushed home to its further end, inverted so as to turn
out the contents, and then immediately withdrawn.

The duration of the process, or the time of completing a distillation,
depends upon the nature of the coal and the form of the retort. With
cylindrical retorts it cannot be finished in less than 6 hours, but with
elliptical and semi-cylindrical retorts, it may be completed in 4 or 5
hours. If the distillation be continued in the former for 8 hours, and
in the latter for 6, gas will continue to be obtained, but during the
latter period of the operation, of indifferent quality.

[Illustration: 484]

_The Receiver._--If the furnace contains only 2 or 3 retorts, a simple
cylindrical vessel standing on the ground half filled with water, may
serve as a receiver; into which the tube from the retort may be plunged.
It should be provided with an overflow pipe for the tar and ammoniacal
liquor. For a range of several retorts, a long horizontal cylinder is
preferable, like that represented at B in _fig._ 484. Its diameter is
from 10 to 15 inches. This cylinder may be so constructed as to separate
the tar from the ammoniacal liquor, by means of a syphon attached to one
of its ends.

_The Condenser._--The condenser, represented in _fig._ 482., consists of
a square chest, _g_, made of wrought iron plates open at top, but having
its bottom pierced with a row of holes, to receive a series of tubes. To
these holes the upright four-inch tubes _h h_ are secured by flanges and
screws, and they are connected in pairs at top by the curved or saddle
tubes. The said bottom forms the cover of the chest _t_, _t_, which is
divided by vertical iron partitions, into half as many compartments as
there are tubes.

These partition plates are left open at bottom, so as to place the
liquids of each compartment in communication. Thereby the gas passes up
and down the series of tubes, in proceeding from one compartment to
another. The condensed liquids descend into the box _t_, _t_, and flow
over into the tar cistern, when they rise above the level _t_, _t_. The
tar may be drawn off from time to time by the stopcock. Through the tube
_k_, cold water flows into the condenser chest, and the warm water
passes away by a pipe at its upper edge.

The extent of surface which the gas requires for its refrigeration
before it is admitted into the washing-lime apparatus, depends upon the
temperature of the milk of lime, and the quantity of gas generated in a
certain time.

It may be assumed as a determination sufficiently exact, that 10 square
feet of surface of the condenser can cool a cubic foot of gas per minute
to the temperature of the cooling water. For example, suppose a furnace
or arch with 5 retorts of 150 pounds of coal each, to produce in 5 hours
3000 cubic feet of gas, or 10 cubic feet per minute, there would be
required, for the cooling surface of the condenser, 100 square feet = 10
× 10. Suppose 100,000 cubic feet of gas to be produced in 24 hours, for
which 8 or 9 such arches must be employed, the condensing surface must
contain from 800 to 900 square feet.

_The Purifier._--The apparatus represented in the preceding figure is
composed of a cylindrical iron vessel, with an air-tight cover screwed
upon it, through which the cylinder _n_ is also fixed air-tight. The
bottom of this cylinder spreads out like the brim of a hat, forming a
horizontal circular partition, which is pierced with holes. Through a
stuffing box, in the cover of this interior cylinder, the vertical axis
of the agitator passes, which is turned by wheel and pinion work, in
order to stir up the lime from the bottom of the water in the purifier.
The vessel _o_ serves for introducing fresh milk of lime, as also for
letting it off by a stopcock when it has become too foul for further
use.

The quantity of lime should be proportioned to the quantity of
sulphuretted hydrogen and carbonic acid contained in the gas. Supposing
that in good coal gas there is 5 per cent. of these gases, about one
pound and a half of lime will be requisite for every hundred cubic feet
of coal gas generated, which amounts to nearly one-sixteenth of the
weight of coal subjected to decomposition. This quantity of lime mixed
with the proper quantity of water will form about a cubic foot of milk
of lime. Consequently, the capacity of the purifier, that is, of the
interior space filled with liquid, may be taken at four-sevenths of a
cubic foot for every hundred cubic feet of gas passing through it in one
operation; or for 175 cubic feet of gas, one cubic foot of liquor. After
every operation, that is, after every five or six hours, the purifier
must be filled afresh. Suppose that in the course of one operation
20,000 cubic feet of gas pass through the machine, this should be able
to contain 20,000/175 = 114 cubic feet of milk of lime; whence its
diameter should be seven feet, and the height of the liquid three feet.
If the capacity of the vessel be less, the lime milk must be more
frequently changed.

In some of the large gas works of London the purifier has the following
construction, whereby an uninterrupted influx and efflux of milk of lime
takes place. Three single purifiers are so connected together, that the
second vessel stands higher than the first, and the third than the
second; so that the discharge tube of the superior vessel, placed
somewhat below its cover, enters into the upper part of the next lower
vessel; consequently, should the milk of lime in the third and uppermost
vessel rise above its ordinary level, it will flow over into the second,
and thence in the same way into the first; from which it is let off by
the eduction pipe. A tube introduces the gas from the condenser into the
first vessel, another tube does the same thing for the second vessel,
&c., and the tube of the third vessel conducts the gas into the
gasometer. Into the third vessel, milk of lime is constantly made to
flow from a cistern upon a higher level. By this arrangement, the gas
passing through the several vessels in proportion as it is purified,
comes progressively into contact with purer milk of lime, whereby its
purification becomes more complete. The agitator _c_, provided with two
stirring paddles, is kept in continual rotation. The pressure which the
gas has here to overcome is naturally three times as great as with a
single purifier of like depth.

[Illustration: 485]

_Fig._ 485. is a simple form of purifier, which has been found to answer
well in practice. Through the cover of the vessel A B, the wide cylinder
_e d_ is inserted, having its lower end pierced with numerous holes.
Concentric with that cylinder is the narrower one _s z_, bound above
with the flange _a b_, but open at top and bottom. The under edge _g h_
of this cylinder descends a few inches below the end _c d_ of the outer
one. About the middle of the vessel the perforated shelf _m n_ is
placed. The shaft of the agitator _l_, passes through a stuffing box
upon the top of the vessel. The gas-pipe _g_, proceeding from the
condenser, enters through the flange _a b_ in the outer cylinder, while
the gas-pipe _h_ goes from the cover to the gasometer. A stopcock upon
the side, whose orifice of discharge is somewhat higher than the under
edge of the outer cylinder, serves to draw off the milk of lime. As the
gas enters through the pipe _g_ into the space between the two
cylinders, it displaces the liquor till it arrives at the holes in the
under edge of the outer cylinder, through which, as well as under the
edge, it flows, and then passes up through the apertures of the shelf _m
n_ into the milk of lime chamber; the level of which is shown by the
dotted line. The stirrer, _l_, should be turned by wheel work, though it
is here shown as put in motion by a winch handle.

In order to judge of the degree of purity of the gas after its
transmission through the lime machine, a slender syphon tube provided
with a stopcock may have the one end inserted in its cover, and the
other dipped into a vessel containing a solution of acetate of lead.
Whenever the solution has been rendered turbid by the precipitation of
sulphuret of lead, it should be renewed. The saturated and fetid milk of
lime is evaporated in oblong cast-iron troughs placed in the ash-pit of
the furnaces, and the dried lime is partly employed for luting the
apparatus, and partly disposed of for a mortar or manure.

By this purifier, and others of similar construction, the gas in the
preceding parts of the apparatus, as in the retorts and the condenser,
suffers a pressure equal to a column of water about two feet high; and
in the last described purifier even a greater pressure. This pressure is
not disadvantageous, but is of use in two respects; 1. it shows by a
brisk jet of gas when the apparatus is not air-tight, and it prevents
common air from entering into the retorts; 2. this compression of the
gas favours the condensation of the tar and ammoniacal liquor. The
effect of such a degree of pressure in expanding the metal of the
ignited retorts is quite inconsiderable, and may be neglected. Two
contrivances have, however, been proposed for taking off this pressure
in the purifier.

[Illustration: 486]

In _fig._ 486., _m m_ are two similar vessels of a round or rectangular
form, furnished at their upper border with a groove filled with water,
into which the under edge of the cover fits, so as to make the vessel
air-tight. The cover is suspended by a cord or chain, which goes over a
pulley, and may be raised or lowered at pleasure. The vessels themselves
have perforated bottoms, _r r´_, covered with wetted moss or hay
sprinkled over with slaked and sifted quicklime. The gas passes through
the loosely compacted matter of the first vessel, by entering between
its two bottoms, rises into the upper space _t_, thence it proceeds to
the second vessel, and, lastly, through the pipe _u_ into the gasometer.
This method, however, requires twice as much lime as the former, without
increasing the purity of the gas.

[Illustration: 487]

The second method consists in compressing the gas by the action of an
Archimedes screw, to such a degree, before it is admitted into the
purifier, as that it may overcome the pressure of the column of water in
that vessel. _Fig._ 487. exhibits this apparatus in section. D D is the
Archimedes worm, the axis of which revolves at bottom upon the gudgeon
_e_; it possesses a three-fold spiral, and is turned in the opposite
direction to that in which it scoops the water. The cistern which
contains it has an air-tight cover. The gas to be purified passes
through the pipe C into the space D, over the water level _d_; the upper
cells of the worm, scoop in the gas at this point, and carry it
downwards, where it enters at _g_ into the cavity E of a second cistern.
In order that the gas, after it escapes from the bottom of the worm, may
not partially return through _g_ into the cavity D, an annular plate _g
h_ is attached to its under edge, so as to turn over it. The compressed
gas is conducted from the cavity E through the pipe G into the purifying
machine; _a_ is a manometer, to indicate the elastic tension of the gas
in D. On the top of the worm a mechanism is fitted for keeping it in
constant rotation.

A perfect purification of light-gas from sulphuretted hydrogen, either
by milk of lime or a solution of the green sulphate of iron, is attended
with some difficulty, when carried so far as to cause no precipitation
of sulphuret in acetate of lead, because such a degree of washing is
required as is apt to diminish its illuminating power, by abstracting
the vapour of the rich oily hydrocarburet which it contains. Moreover,
the coal gas obtained towards the end of the distillation contains some
sulphuret of carbon, which affords sulphurous acid on being burned, and
can be removed by no easy method hitherto known. The lime in the
purifier disengages from the carbonate and hydrosulphuret of ammonia
carried over with the gas, especially when it has been imperfectly
cooled in the condenser, a portion of ammoniacal gas, which, however, is
not injurious to its illuminating power. The best agent for purifying
gas would be the pyrolignite of lead, were it not rather expensive,
because it would save the trouble of stirring, and require a smaller and
simpler apparatus.

_The Gasometer._--The gasometer serves not merely as a magazine for
receiving the gas when it is purified, and keeping it in store for use,
but also for communicating to the gas in the act of burning such an
uniform pressure as may secure a steady unflickering flame. It consists
of two essential parts; 1. of an under cistern, open at top and filled
with water; and 2. of the upper floating cylinder or chest, which is a
similar cistern inverted, and of somewhat smaller dimensions, called the
gas-holder: see F, _fig._ 482. The best form of this vessel is the round
or cylindrical; both because under equal capacity it requires least
surface of metal, and it is least liable to be warped by its own weight
or accidents. Since a cylindrical body has the greatest capacity with a
given surface when its height is equal to its semi-diameter, its
dimensions ought to be such that when elevated to the highest point in
the water, the height may be equal to the radius of the base. For
example, let the capacity of the gas-holder in cubic feet be _k_, the
semi-diameter of its base be _x_, the height out of the water be _h_;
_h_ is = _x_ = ∛(k/3·14). This height may be increased by one or two
feet, according to its magnitude, to prevent the chance of any gas
escaping beneath its under edge, when it is raised to its highest
elevation in the water.

The size of the gasometer should be proportional to the quantity of gas
to be consumed in a certain time. If 120,000 cubic feet be required, for
instance, in 10 hours for street illumination, and if the gas retorts be
charged four times in 24 hours, 30,000 cubic feet of gas will be
generated in 6 hours. Hence the gasometer should have a capacity of at
least 70,000 cubic feet, supposing the remaining 50,000 cubic feet to be
produced during the period of consumption. If the gasometer has a
smaller capacity, it must be supplied from a greater number of retorts
during the lighting period, which is not advantageous, as the first
heating of the supernumerary retorts is wasteful of fuel. Some engineers
consider that a capacity of 30,000 cubic feet is the largest which can
with propriety be given to a gasometer; in which case, they make its
diameter 42 feet, and its height 23. When the dimensions are greater,
the sheet iron must be thicker and more expensive; and the hollow
cylinder must be fortified by strong internal cross braces.

The water cistern is usually constructed in this country with cast-iron
plates bolted together, and made tight with rust-cement.

[Illustration: 488]

In cases where the weight of water required to fill such a cistern might
be inconvenient to sustain, it may be made in the form represented in
_fig._ 488.; which, however, will cost nearly twice as much. Parallel
with the side of the cistern, a second cylinder C, of the same shape but
somewhat smaller, is fixed in an inverted position to the bottom of the
first, so as to leave an annular space B B between them, which is filled
with water, and in which the floating gasometer A plays up and down. The
water must stand above the cover of the inverted cylinder. _a_ and _b_
are the pipes for leading the gas in and out. Through an opening in the
masonry upon which the gasometer apparatus rests, the space C may be
entered, in order to make any requisite repairs.

The water cistern may also be sunk in the ground, and the sides made
tight with hydraulic mortar, as is shown in _fig._ 489., and to make it
answer with less water, a concentric cylindrical mass of masonry may be
built at a distance of 2 or 3 inches within it.

Every large gasometer must be strengthened interiorly with cross iron
rods, to stiffen both its top and bottom. The top is supported by rods
stretching obliquely down to the sides, and to the under edge an iron
ring is attached, consisting of curved cast-iron bars bolted together;
with which the oblique rods are connected by perpendicular ones. Other
vertical rods stretch directly from the top to the bottom edge. Upon the
periphery of the top, at the end of the rods, several rings are made
fast, to which the gas-holder is suspended, by means of a common chain
which runs over a pulley at the centre. Upon the other end of the chain
there is a counterpoise, which takes off the greater part of the weight
of the gas-holder, leaving only so much as is requisite for the
expulsion of the gas. The inner and outer surfaces of the gas-holder
should be a few times rubbed over with hot tar, at a few days’ interval
between each application. The pulley must be made fast to a strong
frame.

[Illustration: 489]

If the water cistern be formed with masonry, the suspension of the
gas-holder may be made in the following way. A A, _fig._ 489., is a
hollow cylinder of cast iron, standing up through the middle of the
gasometer, and which is provided at either end with another small hollow
cylinder G, open at both ends and passing through the top, with its axis
placed in the axis of the gas-holder. In the hollow cylinder G, the
counterweight moves up and down, with its chain passing over the three
pulleys B, B, B, as shown in _fig._ 489. E F are the gas pipes made fast
to a vertical iron rod. Should the gasometer be made to work without a
counterweight, as we shall presently see, the central cylinder A A,
serves as a vertical guide.

In proportion as the gas-holder sinks in the water of the cistern, it
loses so much of its weight, as is equal to the weight of the water
displaced by the sides of the sinking vessel; so that the gas-holder
when entirely immersed, exercises the least pressure upon the gas, and
when entirely out of the water, it exercises the greatest pressure. In
order to counteract this inequality of pressure, which would occasion an
unequal velocity in the efflux of the gas, and of course an unequal
intensity of light in its flame, the weight of the chain upon which the
gas-holder hangs is so adjusted as to be equal, throughout the length of
its motion, to one half of the weight which the gas-holder loses by
immersion. In this case, the weight which it loses by sinking into the
water, is replaced by the portion of the chain which passing the pulley,
and hanging over, balances so much of the chain upon the side of the
counterweight; and the weight which it gains by rising out of the water,
is counterpoised by the links of the chain which passing over the
pulley, add to the amount of the counterweight. The pressure which the
gas-holder exercises upon the gas, or that with which it forces it
through the first main pipe, is usually so regulated as to sustain a
column of from one to two inches of water; so that the water will stand
in the cistern from one to two inches higher within, than without the
gas-holder. The following computation will place these particulars in a
clear light.

Let the semi-diameter of the gas-holder, equal to the vertical extent of
its motion into and out of the water, = _x_; let the weight of a foot
square of the side of the gas-holder, including that of the
strengthening bars and ring, which remain plunged under the water, be =
_p_; then

1. the weight of the gas-holder in its highest position =

  3 _p_ π _x_²;

2. the weight of the sides of the gas-holder which play in the water =

  2 _p_ π _x_²;

3. the cubic contents of the immersed portion of the gas-holder =

  2 _p_ π _x_²
  ------------
      400;

4. its loss of weight in water =

  112
  --- _p_ π _x_²;
  400

5. the weight of the gas-holder in its lowest position =

             (    112)
  _p_ π _x_² (3 - ---) = 2·72 _p_ π _x_²;
             (    400)

6. the weight of _n_ inches, height of water =

  56
  -- _n_ π _x_²;
  12

7. the amount of the counterweight =

         (        56 _n_)
  π _x_² (3 _p_ - ------);
         (          12  )

8. the weight of the chain for the length _x_ =

  112
  --- _p_ π _x_.
  800

If we reduce the weight of the gas-holder in its highest and lowest
positions to the height of a stratum of water equal to the surface of
its top, this height is that of the column of water which would press
the gas within the gasometer, were no counterweight employed; it
consists as follows;--

9. for the highest position =

  3 _p_
  -----;
   56

10. for the lowest =

  2·72 _p_
  --------;
     50

For the case, when the height of the gas-holder is different from its
semi-diameter, let this height = _m x_; then the height of the water
level is

11. for the highest position =

      (1 + 2 _m_)
  _p_ (---------);
      (   56    )

12. for the lowest =

      (1 + 1·72 _m_)
  _p_ (------------);
      (      6     )

13. the counterweight =

         (                  56 _n_)
  π _x_² (_p_ (1 + 2 _m_) - ------);
         (                    12  )

14. the weight of the equalizing chain =

  112
  --- _p_ π _m_ _x_².
  800

For example, let the diameter of the gas-holder be 30 feet, the height
15 (the contents in cubic feet will be 10,597), _p_ = 4 pounds; then the
counterweight for a height of an inch and a half of water pressure =
3532 pounds; the weight of the chain for a length of 15 feet = 395
pounds. Were no counterweight employed, so that the gas-holder pressed
with its whole weight upon the gas, then the height of the equivalent
column of water in its highest position = 2·56 inches; and in its
lowest, 2·33. The counterweight may hence be lessened at pleasure, if
the height of the pressing water-column _n_ be increased. The weight of
the equalising or compensating portion of the chain remains the same.
When _n_ = 2 inches, for instance, the counterweight = 1886 pounds.

The velocity with which the gas passes along the mains for supplying the
various jets of light, may be further regulated by opening the main-cock
or slide-valve in a greater or less degree.

Gasometers whose height is greater than their semi-diameter, are not
only more costly in the construction, but require heavier counterweights
and equilibration chains.

The above estimate is made on the supposition of the gas in the
gas-holder being of the same specific gravity as the atmospherical air,
which would be nearly true with regard to oil gas under the ordinary
pressure. But coal gas, whose specific gravity may be taken on an
average at about 0·5, exercises a buoyancy upon the top of the
gas-holder, which of course diminishes its absolute weight. Supposing
the cubic foot of gas to be = 0·0364 pounds, the buoyancy will be =
0·0364 π _x_³ pounds; a quantity which deserves to be taken into account
for large gasometers. Hence,

15. the weight of the gas-holder in its highest position =

  3 _p_ π _x_² - 0·1143 _x_³;

16. the counterweight =

         (        56 _n_)
  π _x_² (3 _p_ - ------) - 0·1143 _x_²;
         (          12  )

17. The weight of the chain for the length _x_, =

  112               0·1143 _x_³
  --- _p_ π _x_² --------------;
  800                     2

18. The height of the water pressure for the highest position, without
the counterweight =

  3 _p_ π - 0·1143 _x_
  --------------------;
        56 π

19. the same for the lowest position =

  2·72 _p_
  -------- in feet.
     56

The preceding values of _p_ and _x_, are,

(16) = 3147; (17) = 203; (18) = 2·44 inches; (19) = 2·33 inches.

The water columns in the highest and lowest situations of the gas-holder
here differ about 0·1 of an inch, and this difference becomes still less
when _p_ has a smaller value, for example, 3 pounds, or when the
diameter of the gas-holder is still greater.

It would thus appear that for coal-gas gasometers, in which the height
of the gas-holder does not exceed its semi-diameter, and especially when
it has a considerable size, neither a compensation chain nor a
counterweight is necessary. The only thing requisite, is to preserve the
vertical motion of the gas-holder by a sufficient number of guide rods
or pillars, placed either within the water cistern, or round about it.
Should the pressure of the gas in the pipe proceeding from the
gasometer, be less than in the gasometer itself, this may be regulated
by the main valve, or by water valves of various kinds. Or a small
intermediate regulating gasometer may be introduced between the great
gas-holder, and the main pipe of distribution. With a diameter of 61
feet in the gas-holder, the pressure in the highest and lowest positions
is the same.

The gasometers employed in storing up gas until required for use,
occupy, upon the old plan, much space, and are attended with
considerable expense in erecting. The water tank, whether sunk in the
ground, or raised, must be of equal dimensions with the gasometer, both
in breadth and depth. The improved construction which we are about to
describe, affords a means of reducing the depth of the tank, dispensing
with the bridge of suspension, and of increasing at pleasure the
capacity of the gasometer, upon a given base; thus rendering a small
apparatus capable, if required, of holding a large quantity of gas, the
first cost of which will be considerably less than even a small
gasometer constructed upon the ordinary plan.

[Illustration: 490]

Mr. Tait, of Mile-End Road, the inventor, has, we believe, been for some
years connected with gas establishments, and is therefore fully aware of
the practical defects or advantages of the different constructions of
gasometers now in use. _Fig._ 490. is a section of Mr. Tait’s improved
contrivance; _a a_ is the tank, occupied with water, _b b_ two iron
columns, with pulley-wheels on the top, _c c_, chains attached to a ring
of iron, _d d_, extending round the gasometer, which chains pass over
the pulley-wheels, and are loaded at their extremities, for the purpose
of balancing the weight of the materials of which the gasometer is
composed.

The gasometer is formed by 2 or 3 cylinders, sliding one within the
other, like the tubes of a telescope; _e_, _e_, _e_, is the first or
outer cylinder, closed at the top, and having the ring of iron _d_,
passing round it, by which the whole is suspended; _f f_, is the second
cylinder, sliding freely within the first, and there may be a third and
fourth within these if necessary.

When there is no gas in the apparatus, all the cylinders are slidden
down, and remain one within the other immersed in the tank of water; but
when the gas rises through the water pressing against the top of the
gasometer, its buoyancy causes the cylinder _e_ to ascend. Round the
lower edge of this cylinder a groove is formed by the turning in of the
plate of iron, and as it rises, the edge takes hold of the top rim of
the cylinder _f_, which is overlapped for that purpose. The groove at
the bottom of the cylinder fills itself with water as it ascends, and by
the rim of the second cylinder falling into it, an air-tight hydraulic
joint is produced.

Thus, several cylinders may be adapted to act in a small tank of water,
by sliding one within the other, with lapped edges forming hydraulic
joints, and by supporting the apparatus in the way shown, the centre of
gravity will always be below the points of suspension. A gasometer may
be made upon this plan of any diameter, as there will be no need of
frame work, or a bridge to support it; and the increasing weight of the
apparatus, as the cylinders are raised one after the other, may be
counterpoised by loading the ends of the chains _c c_.

The water in the gasometer need not be renewed; but merely so much of it
as evaporates or leaks out, is to be replaced. Indeed the surface of the
water in the cistern gets covered with a stratum of coal oil, a few
inches deep, which prevents its evaporation, and allows the gas to be
saturated with this volatile substance, so as to increase its
illuminating powers.

[Illustration: 491]

The gasometer may be separated from the purifier by an intermediate
vessel, such as is represented _fig._ 491., with which the two gas pipes
are connected. A is the cylindrical vessel of cast iron, _a_, the end
of the gas pipe which comes from the purifier, immersed a few inches
deep into the liquid with which the vessel is about two-thirds filled;
_b_ is the gas-pipe which leads into the gasometer, _c_ is a
perpendicular tube, placed over the bottom of the vessel, and reaching
to within one-third of the top, through which the liquid is introduced
into the vessel, and through which it escapes when it overflows the
level _d_. In this tube the liquid stands towards the inner level
higher, in proportion to the pressure of the gas in the gasometer. The
fluid which is condensed in the gas pipe, _b_, and in its prolongation
from the gasometer, runs off into the vessel A; and therefore the latter
must be laid so low that the said tube may have the requisite declivity.
A straight stop-cock may also be attached to the side over the bottom,
to draw off any sediment.

II. APPLICATION OF LIGHT-GAS.

1. _Distribution of the pipes_.--The pressure by which the motion of the
gas is maintained in the pipes, corresponds to a certain height of water
in the cistern of the gasometer. From the magnitude of this pressure,
and the quantity of gas which in a given time, as an hour, must be
transmitted through a certain length of pipes, depends the width or the
diameter that they should have, in order that the motion may not be
retarded by the friction which the gas, like all other fluids,
experiences in tubes, and thereby the gas might be prevented from
issuing with the velocity required for the jets of flame. The velocity
of the gas in the main pipe increases in the ratio of the square root of
the pressing column of water upon the gasometer, and therefore by
increasing this pressure, the gas may be forced more rapidly along the
remoter and smaller ramifications of the pipes. Thus it happens,
however, that the gas will be discharged from the orifices near the
gasometer, with superfluous velocity. It is therefore advisable to lay
the pipes in such a manner, that in every point of their length, the
velocity of discharge may be nearly equal. This may be nearly effected
as follows;--

From experiment it appears that the magnitude of the friction, or the
resistance which the air suffers in moving along the pipes, under a like
primary pressure, that is for equal initial velocity, varies with the
square root of the length. The volume of gas discharged from the end of
a pipe, is directly proportional to the square of its diameter, and
inversely as the square root of its length; or, calling the length L,
the diameter D, the cubic feet of gas discharged in an hour _k_; then
_k_ = D²/√L. Experience likewise shows, that for a pipe 250 feet long,
which transmits in an hour 200 cubic feet of gas, one inch is a
sufficient diameter.

Consequently,

                 1         D²            √(_k_ √L)
  200 : _k_ ∷ --------  :  --;  and D = ---------
              144 √250     √L              455,000

From this formula the following table of proportions is calculated.

  +---------------+---------------+----------+
  |Number of cubic|Length of pipe,|Diameter, |
  |feet per hour. |  in feet.     |in inches.|
  +---------------+---------------+----------+
  |      50       |      100      |   0·40   |
  |     250       |      200      |   1·00   |
  |     500       |      600      |   1·97   |
  |     700       |     1000      |   2·65   |
  |    1000       |     1000      |   3·16   |
  |    1500       |     1000      |   3·87   |
  |    2000       |     1000      |   4·47   |
  |    2000       |     2000      |   5·32   |
  |    2000       |     4000      |   6·33   |
  |    2000       |     6000      |   7·00   |
  |    6000       |     1000      |   7·75   |
  |    6000       |     2000      |   9·21   |
  |    8000       |     1000      |   8·95   |
  |    8000       |     2000      |  16·65   |
  +---------------+---------------+----------+

These dimensions are applicable to the case where the body of gas is
transmitted through pipes without being let off in its way by burners,
that is, to the mains which conduct the gas to the places where it is to
be used. If the main sends off branches for burners, then for the same
length the diameter may be reduced, or for like diameter the length may
be greater. For example, if a pipe of 5·32 inches, which transmits 2000
cubic feet through a length of 2000 feet, gives off, in this space, 1000
cubic feet of gas; then the remainder of the pipe, having the same
diameter, can continue to transmit the gas through a length of 2450 feet
= (450,000/_k_)², with undiminished pressure for the purposes of
lighting. Inversely, the diameter should be progressively reduced in
proportion to the number of jets sent off in the length of the pipe.

Suppose for instance, the gasometer to discharge 2000 cubic feet per
hour, and the last point of the jets to be at a distance of 4000 feet.
Suppose also that from the gasometer to the first point of lighting, the
gas proceeds through 1000 feet of close pipe, the diameter of the pipe
will be here 4·47 inches; in the second 1000 feet of length, suppose the
pipe to give off, at equal distances, 1000 cubic feet of gas, the
diameter in this length (calculated at 1500 cubic feet for 1000 feet
long) = 3·87 inches; in the third extent of 1000 feet, 600 cubic feet of
gas will be given off, and the diameter (reckoning 700 cubic feet for
1000 feet long) will be 2·65 inches; in the fourth and last space (for
200 cubic feet in 1000 feet long) the pipe has a diameter of only an
inch and a half, for which, in practice, a two-inch cast iron pipe is
substituted; this being the smallest used in mains, into which branch
pipes can be conveniently inserted.

The same relations hold with regard to branch pipes through which the
gas is transmitted into buildings and other places to be illuminated. If
such pipes make frequent angular turnings, whereby they retard the
motion of the gas, they must be a third or a half larger in diameter.
The smallest tubes of distribution are never less than one fourth of an
inch in the bore.

Where, from one central gas work, a very great quantity of light is
required in particular localities, there ought to be placed near these
spots gasometers of distribution, which, being filled during the slack
hours of the day, are ready to supply the burners at night, without
making any considerable demand upon the original main pipe. Suppose the
first main be required to supply 8000 cubic feet in the hour, for an
illumination of 8 hours, at the distance of 2000 feet, a pipe 10-2/3
inches in diameter would be necessary; but if two or three gasometers of
distribution, or station gasometers be had recourse to, into which the
gas during the course of 24 hours would flow through the same distance
continuously from the central gas works, the quantity required per hour
from them would be only one third of 8000, = 2666·6 cubic feet;
consequently the diameter for such a pipe is only 6·15 inches.

[Illustration: 492]

All the principal as well as branch pipes, whose interior diameter
exceeds an inch and a half, are made of cast iron from 6 to 8 feet long,
with elbow pipes cast in them where it is necessary. These pipe lengths
are shown in _fig._ 492., having at one end a wide socket _a_, and at
the other a nozzle _b_, which fits the former. After inserting the one
in the other in their proper horizontal position, a coil of hemp soaked
with tar is driven home at the junction; then a luting of clay is
applied at the mouth, within which a ring of lead is cast into the
socket, which is driven tight home with a mallet and blunt chisel.

The pipes should be proved by a force pump before being received into
the gas works; two or three lengths of them should be joined before
laying them down, and they should be placed at least two feet below the
surface, to prevent their being affected by changes of temperature,
which would loosen the joints. The tubes for internal distribution, when
of small size are made of lead, copper, wrought iron, or tin.

[Illustration: 493]

Instead of a stopcock for letting off the gas in regulated quantities
from the gasometer, a peculiarly formed water or mercurial valve is
usually employed. _Fig._ 493. shows the mode of construction for a water
trap or lute, and is, in fact, merely a gasometer in miniature. C D E F
is a square cast iron vessel, in the one side of which a pipe A is
placed in communication with the gasometer, and in the other, one with
the main B. The movable cover or lid H G I K has a partition, L M, in
its middle. If this cover be raised by its counterweight, the gas can
pass without impediment from A to B; but if the counterweight be
diminished so as to let the partition plate L M sink into the water, the
communication of the two pipes is thereby interrupted. In this case the
water-level stands in the compartment A so much lower than outside of
it, and in the compartment B, as is equivalent to the pressure in the
gasometer; therefore the pipes A and B must project thus far above the
water. In order to keep the water always at the same height, and to
prevent it from flowing into the mouths of these pipes, the rim C D of
the outer vessel stands somewhat lower than the orifices A B; and thence
the vessel may be kept always full of water.

[Illustration: 494]

If a quicksilver valve be preferred, it may be constructed as shown in
_fig._ 494. A B are the terminations of the two gas pipes, which are
made fast in the rectangular iron vessel M. E is an iron vessel of the
same form, which is filled with quicksilver up to the level _a_, and
which, by means of the screw G, which presses against its bottom, and
works in the fixed female screw C C, may be moved up or down, so that
the vessel M may be immersed more or less into the quicksilver. The
vessel M is furnished with a vertical partition _m_; the passage of the
gas from A to B is therefore obstructed when this partition dips into
the quicksilver, and from the gradual depression of the vessel E by its
screw, the interval between the quicksilver and the lower edge of the
partition, through which the gas must enter, may be enlarged at
pleasure, whereby the pressure of the gas in B may be regulated to any
degree. The transverse section of that interval is equal to the area of
the pipe or rather greater; the breadth of the vessel M from A to B
amounts to the double of that space, and its length to the mere diameter
of A or B. The greatest height to which the partition _m_ can rise out
of the quicksilver, is also equal to the above diameter, and in this
case the line _a_ comes to the place of _b_. The vertical movement of
the outer vessel E, is secured by a rectangular rim or hoop which
surrounds it, and is made fast to the upper part of the vessel M, within
which guide it moves up and down. Instead of the lever D D, an index
with a graduated plate may be employed to turn the screw, and to
indicate exactly the magnitude in the opening of the valve.

[Illustration: 495]

In order to measure the quantity of gas which passes through a pipe for
lighting a factory, theatre, &c., the gas-meter is employed, of whose
construction a sufficiently precise idea may be formed from the
consideration of _fig._ 495., which shows the instrument in a section
perpendicular to its axis.

Within the cylindrical case _a_, there is a shorter cylinder _b b_, shut
at both ends, and movable round an axis, which is divided into four
compartments, that communicate by the opening _d_, with the interval
between this cylinder and the outer case. The mode in which this
cylinder turns round its axis is as follows:--The end of the tube _c_,
which is made fast to the side of the case, and by which the gas enters,
carries a pivot or gudgeon, upon which the centre of its prop turns; the
other end of the axis runs in the cover, which here forms the side of a
superior open vessel, in which, upon the same axis, there is a toothed
wheel. The vessel is so far filled with water, that the tube _c_ just
rises above it, which position is secured by the level of the side
vessel. When the gas enters through the tube _c_, by its pressure upon
the partition _e_, (_fig._ 495.) it turns the cylinder from right to
left upon its axis, till the exterior opening _d_ rises above the water,
and the gas expands itself in the exterior space, whence it passes off
through a tube at top. At every revolution a certain volume of gas thus
goes through the cylinder, proportional to its known capacity. The wheel
on the axis works in other toothed wheels, whence, by means of an index
upon a graduated disc or dial, placed at top or in front of the
gas-meter, the number of cubic feet of gas, which pass through this
apparatus in a given time, is registered.

B. _Employment of the gas for lighting._--The illuminating power of
different gases burned in the same circumstances, is proportional,
generally speaking, to their specific gravity, as this is to the
quantity of carbon they hold in combination. The following table
exhibits the different qualities of gases in respect to illumination.

  +-------------------+----------------------------+
  |    Density or     |Proportion of light afforded|
  | specific gravity. |  by coal gas to oil gas.   |
  +----------+--------+----------------------------+
  | Coal gas.|Oil gas.|                            |
  +----------+--------+                            |
  |     0·659| 0·818  |        100 : 140           |
  |     0·578| 0·910  |        100 : 225           |
  |     0·605| 1·110  |        100 : 250           |
  |     0·407| 0·940  |        100 : 354           |
  |     0·429| 0·965  |        100 : 356           |
  |     0·508| 1·175  |        100 : 310           |
  +----------+--------+----------------------------+
  |Mean 0·529| 0·96   |        100 : 272           |
  +----------+--------+----------------------------+

In the last three proportions, the coal gas was produced from coals of
middle quality; in the first three proportions from coals of good
quality; and therefore the middle proportion of 100 to 270 may be taken
to represent the fair average upon the great scale. On comparing the gas
from bad coals, with good oil gas, the proportion may become 100 to 300.
Nay, coal gas of specific gravity 0·4, compared to oil gas of 1·1, gives
the proportion of 1 to 4. A mould tallow candle, of 6 in the pound,
burning for an hour, is equivalent to half a cubic foot of ordinary coal
gas, and to four tenths of a foot of good gas. The flame of the best
argand lamp of Carcel, in which a steady supply of oil is maintained by
pump-work, consuming 42 grammes = 649 grains English in an hour, and
equal in light to 9·38 such candles, is equivalent to 3·75 cubic feet of
coal gas per hour. The sinumbra lamp, which consumes 50 grammes = 772
grains English, of oil per hour, and gives the light of 8 of the above
candles, is equivalent to the light emitted by 3·2 cubic feet of coal
gas burning for an hour. A common argand lamp, equal to 4 candles, which
consumes 30 grammes = 463 grains English per hour, is represented by 1·6
cubic feet of gas burning during the same time. A common lamp, with a
flat wick and glass chimney, whose light is equal to 1·13 tallow
candles, and which consumes 11 grammes = 169·8 grains English per hour,
is represented by 0·452 of a cubic foot of gas burning for the same
time.

_Construction of the Burners._--The mode of burning the gas as it issues
from the jets has a great influence upon the quantity and quality of its
light. When carburetted hydrogen gas is transmitted through ignited
porcelain tubes, it is partially decomposed with a precipitation of some
of its carbon, while the resulting gas burns with a feebler flame. Coal
gas, when kindled at a small orifice in a tube, undergoes a like
decomposition and precipitation. Its hydrogen, with a little of its
carbon, burns whenever it comes into contact with the atmospherical air,
with a bluish coloured flame; but the carbonaceous part not being so
accendible, takes fire only when mixed with more air; therefore at a
greater distance from the beak, and with a white light from the vivid
ignition of its solid particles. Upon this principle pure hydrogen gas
may be made to burn with a white instead of its usual blue flame, by
dusting into it particles of lamp black; or by kindling it at the
extremity of a tube containing finely pulverized zinc. The metallic
particles become ignited, and impart their bright light to the pale blue
flame. Even platinum wire and asbestos, when placed in the flame of
hydrogen gas, serve to whiten it. Hence it has been concluded, that the
intensity of light which a gas is capable of affording is proportional
to the quantity of solid particles which it contains, and can
precipitate in the act of burning. Carbonic oxide gas burns with the
feeblest light next to hydrogen, because it deposits no carbon in the
act of burning. Phosphuretted hydrogen gives a brilliant light, because
the phosphoric acid, into which its base is converted during the
combustion, is a solid substance, capable of being ignited in the flame.
Olefiant gas, as also the vapour of hydro-carbon oil, emits a more vivid
light than common coal gas; for the first is composed of two measures of
hydrogen and two measures of the vapour of carbon condensed into one
volume; while the last contains only one measure of the vapour of carbon
in the same bulk, and combined with the same proportion of hydrogen.
Olefiant gas may therefore be expected to evolve a double quantity of
carbon in its flame, which should emit a double light.

The illuminating power of the flame of coal gas is, on the contrary,
impaired, when, by admixture with other species of gas which precipitate
no carbon, its own ignited particles are diffused over a greater
surface. This happens when it is mixed with hydrogen, carbonic oxide,
carbonic acid, and nitrogen gases, and the diminution of the light is
proportional to the dilution of the coal gas.

[Illustration: 496 497]

In like manner the illuminating power of coal gas is impaired, when it
is consumed too rapidly to allow time for the separation and ignition of
its carbonaceous matter; it burns, in this case, without decomposition,
and with a feeble blue flame. 1. This occurs when the light-gas is
previously mixed with atmospherical air, because the combustion is
thereby accelerated throughout the interior of the flame, so as to
prevent the due separation of carbon. A large admixture of atmospherical
air makes the flame entirely blue. 2. When it issues, with considerable
velocity, from a minute orifice, whereby the gas, by expansion, gets
intimately mixed with a large proportion of atmospherical air. If the
jet be vertical, the bottom part of the flame is blue, and the more so
the less carbon is contained in the gas. The same thing may be observed
in the flame of tallow, wax, or oil lights. The burning wick acts the
part of a retort, in decomposing the fatty matter. From the lower part
of the wick the gases and vapours of the fat issue with the greatest
velocity, and are most freely mixed with the air; while the gases
disengaged from the upper part of the wick compose the interior of the
flame, and being momentarily protected from the action of the
atmosphere, acquire the proper high temperature for the deposition of
carbon, which is then diffused on the outer surface in an ignited state,
and causes its characteristic white light. Hence with coal gas, the
light increases in a certain ratio with the size of the flame as it
issues from a larger orifice, because the intermixture of air becomes
proportionately less. 3. If by any means too great a draught be given to
the flame, its light becomes feebler by the rapidity and completeness
with which the gas is burned, as when too tall a chimney is placed over
an argand burner, see _fig._ 496. _Fig._ 497. _c_, is a view of the
upper plate, upon which the glass chimney _b_ rests. The gas issues
through the smaller openings of the inner ring, and forms a hollow
cylindrical flame, upon the outside as well as the inside of which the
atmospherical air acts. The illuminating power of this flame may be
diminished at pleasure, according as more or less air is allowed to
enter through the orifices beneath. With a very full draught the light
almost vanishes, leaving only a dull blue flame of great heating power,
like that of the blowpipe, corresponding to the perfect combustion of
the gas without precipitation of its carbon. 4. On the other hand, too
small a draught of air is equally prejudicial; not merely because a
portion of the carbon thus escapes unconsumed in smoke, but also because
the highest illuminating power of the flame is obtained only when the
precipitated charcoal is heated to whiteness, a circumstance which
requires a considerable draught of air. Hence the flame of dense oil
gas, or of oil in a wick, burns with a yellow light without a chimney;
but when it is increased in intensity by a chimney draught, it burns
with a brilliant white flame.

From the consideration of the preceding facts, it is possible to give to
coal gas its highest illuminating power. The burners are either simple
beaks perforated with a small round hole, or circles with a series of
holes to form an argand flame, as shown in _fig._ 497, or two holes
drilled obliquely, to make the flame cross, like a swallow’s tail, or
with a slit constituting the sheet of flame called a bat’s wing, like
most of the lamps in the streets of London. These burners are mounted
with a stop-cock for regulating the quantity of gas.

The height of the flame, which with like pressure depends upon the size
of the orifice, and with like orifice upon the amount of pressure, the
latter being modified by the stop-cock, is for simple jets in the open
air, as follows:--

  Length of the flame            2       3      4     5     6 inches
  Intensity of the light        55·6    100    150  197·8  247·4
  Volume of gas consumed        60·5  101·4  126·3  143·7  182·2
  Light with equal consumption   100    109    131    150    150

When the length exceeds five inches, nothing is gained in respect to
light. For oil gas the same statements will serve, only on account of
its superior richness in carbon, it does not bear so long a flame
without smoke. Thus:--

  Length of the flame             1     2     3    4    5 inches
  Intensity of the light          22  63·7  96·5  141  178
  Gas consumed                  33·1  78·5    90  118  153
  Light with equal consumption   100   122   159  181  174

The diameter of the orifice for single jets, or for several jets from
the same beak, is one twenty-eighth of an inch for coal gas, and one
forty-fifth for oil gas.

[Illustration: 498 499]

When several jets issue from the same burner, the light is improved by
making all the flames unite into one. In this case the heat becomes
greater, for the combined flame presents a smaller surface to be cooled,
than the sum of the smaller flames. The advantage gained in this way,
may be in the ratio of 3 to 2, or 50 per cent. In an argand burner, the
distances of the orifices for coal gas should be from 16/100 to 18/100
of an inch, and for oil gas 12/100. If the argand ring has ten orifices,
the diameter of the central opening should be = 4/10 of an inch; if 25
orifices, it should be one inch for coal gas; but for oil gas with 10
orifices, the central opening should have a diameter of half an inch,
and for 20 orifices, one inch. The pin holes should be of equal size,
otherwise the larger ones will cause smoke, as in an argand flame with
an uneven wick. The glass chimney is not necessary to promote the
combustion of an argand coal gas flame, but only to prevent it from
flickering with the wind, and therefore it should be made so wide as to
exercise little or no influence upon the draught. A narrow chimney is
necessary merely to prevent smoke, when a very strong light, with a
profusion of gas is desired. Oil gas burned in an argand beak requires a
draught chimney, like a common argand lamp, on account of the large
quantity of carbon to be consumed. The most suitable mode of regulating
the degree of draught can be determined only by experiment, and the best
construction hitherto ascertained is that represented in _fig._ 498.
_Fig._ 499. exhibits the view from above, of the rim or ring _c_, upon
which the chimney _b_ stands, and which surrounds the perforated beak.
The ring is made of open fretwork, to permit the free passage of air
upwards to strike the outside of the flame. The thin annular disc _d_,
which is laid over its fellow disc _c_, in the bottom of the
chimney-holder, being turned a little one way or other, will allow more
or less air to pass through for promoting more or less, the draught or
ventilation. The draught in the central tube of the burner may be
regulated by the small disc _e_, whose diameter is somewhat smaller than
that of the ring of the burner, and which by turning the milled head
_f_, of the screw, may be adjusted with the greatest nicety, so as to
admit a greater or smaller body of air into the centre of the
cylindrical flame.

In mounting gas-lights, and in estimating beforehand their illuminating
effects, we must keep in mind the optical proposition, that the quantity
of light is inversely as the square of the distance from the luminous
body, and we must distribute the burners accordingly. When for example a
gas-light placed at a distance of ten feet, is required for reading or
writing to afford the same light as a candle placed at a distance of two
feet; squaring each distance, we have 100 and 4; therefore 100/4 = 25,
shows us that 25 such lights will be necessary at the distance of 10
feet.

Concerning portable gas-light, with the means of condensing it, and
carrying it from the gas works to the places where it is to be consumed,
we need say nothing, as by the improvements lately made in the
purification and distribution of coal-gas, the former system has been
superseded.

It is well known that light gas deteriorates very considerably by
keeping, especially when exposed to water over an extensive surface; but
even to a certain degree over oil, or in close vessels. An oil-gas which
when newly prepared has the specific gravity of 1·054, will give the
light of a candle for an hour, by consuming 200 cubic inches; will,
after two days, give the same light by consuming 215 cubic inches per
hour; and after four days, by consuming 240 cubic inches in the like
time. With coal-gas the deterioration appears to be more rapid. When
newly prepared, if it affords the light of a candle with a consumption
of 400 cubic inches per hour; it will not give the same light after
being kept two days, except with a consumption of 430 inches; and after
four days, of 460. Oil-gas three weeks old has become so much impaired
in quality that 600 inches of it were required per hour to furnish the
light of a candle. All light gas should be used therefore as soon as
possible after it is properly purified.

_Economical considerations._--The cost of gas-light depends upon so many
local circumstances, that no estimate of it can be made of general
application; only a few leading points may be stated. The coals
required for heating the retorts used to constitute one half of the
quantity required for charging the retorts themselves. When five retorts
are heated by one fire, the expenditure for fuel is only one third of
that when each retort has a fire. The coak which remains in the retorts
constitutes about 60 per cent. of the weight of the original coal; but
the volume is increased by the coaking in the proportion of 100 to 75.
When the coak is used for heating the retorts, about one half of the
whole is required. If we estimate the coak by its comparative heating
power, it represents 65 per cent. of the coals consumed. One hundred
pounds of good coal yield in distillation 10 pounds of ammoniacal
liquor, from which sulphate or muriate of ammonia may be made, by
saturation with sulphuric or muriatic acid, and evaporation. The liquor
contains likewise some cyanide of ammonia, which may be converted into
prussian blue by the addition of sulphate of iron, after saturation with
muriatic acid.

Two hundred pounds of coal afford about 17 pounds of tar. This contains
in 100 pounds 26 pounds of coal oil, and 48 pounds of pitch. The tar is
sometimes employed as a paint to preserve wood and walls from the
influence of moisture, but its disagreeable smell limits its use. The
coal oil when rectified by distillation, is extensively employed for
dissolving caoutchouc in making the varnish of waterproof cloth, and
also for burning in a peculiar kind of lamps under the name of naphtha.
Oil of turpentine however is often sold and used for this purpose, by
the same name. If the coal oil be mixed with its volume of water, and
the mixture be made to boil in a kettle, the mingled vapours when passed
through a perforated nozzle may be kindled, and employed as a powerful
means of artificial heat. The water is not decomposed, but it serves by
its vapour to expand the bulk of the volatile oil, and to make it
thereby come into contact with a larger volume of atmospherical air, so
as to burn without smoke, under a boiler or any other vessel. The pitch
may be decomposed into a light-gas.

The relative cost of light from coal gas and oil gas may be estimated as
one to six, at least. Rosin gas is cheaper than oil gas. See ROSIN.

I shall conclude this article with a summary of the comparative expense
of different modes of illumination, and some statistical tables.

One pound of tallow will last 40 hours in six mould candles burned in
succession, and costs 8_d._; a gallon of oil, capable of affording the
light of 15 candles, for 40 hours costs 5_s._, being therefore 1/2 of
the price of mould candles, and 6/15 of the price of dips. The cost of
wax is about 3-1/2 times that of tallow; and coal gas, as sold at the
rate of 9_s._ for 1000 cubic feet, will be one sixth the price of mould
candles; for 500 cubic inches of coal gas give a light equal to the
above candle for an hour; therefore 40 × 500 = 20,000 cubic inches =
11·57 cubic feet, worth 1-1/4_d._, which multiplied by 6 gives 7-1/2_d._
the average price of mould candles per pound.

The author of the article _Gas-light_ in the Encyclopædia Britannica,
observes, in reference to the economy of this mode of illumination, that
while the price of coal, in consequence of the abundant and regular
supply of that article, is liable to little fluctuation, the cost of
wax, tallow, and oil, on account of the more precarious nature of the
sources from which they are obtained, varies exceedingly in different
seasons. “Assuming that a pound of tallow candles, which last when
burned in succession forty hours, costs nine-pence,” (seven-pence
halfpenny is the average price), “that a gallon of oil, yielding the
light of 600 candles for an hour, costs two shillings,” (five shillings
is the lowest price of a gallon of such oil as a gentleman would choose
to burn in his lamp), “that the expense of the light from wax is three
times as great as from tallow, and that a thousand cubic feet of coal
gas cost nine shillings;” he concludes the relative cost to be for the
same quantity of light,--from wax, 100; tallow, 25; oil, 5; and
coal-gas, 3. I conceive the estimate given above to be much nearer the
truth; when referred to wax called 100, it becomes, for tallow, 28·6;
oil, 14·3; coal gas, 4·76.

Gas-lighting has received a marvellous development in London. In the
year 1834, the number of gas lamps in this city was 168,000, which
consumed daily about 4,200,000 cubic feet of gas. For the purpose of
generating this gas, more than 200,000 chaldrons, or 10,800,000 cubic
feet of coals were required.

For the following valuable statistical details upon gas-light, my
readers are indebted to Joseph Hedley, Esq., engineer, of the Alliance
Gas Works, Dublin; a gentleman who to a sound knowledge of chemistry,
joins such mechanical talent and indefatigable diligence, as qualify him
to conduct with success, any great undertaking committed to his care. He
has long endeavoured to induce the directors of the London gas-works to
employ a better coal, and generate a more richly carburetted gas, which
in much smaller quantity would give as brilliant a light, without
heating the apartments unpleasantly, as their highly hydrogenated gas
now does. Were his judicious views adopted, coal gas would soon
supersede oil, and even wax candles, for illuminating private mansions.

Copy of a paper laid before a Committee of the House of Commons, showing
not only the relative values of the Gases produced at the undermentioned
places, but showing in like manner the relative economy of Gas as
produced at the different places, over candles. By Joseph Hedley, Esq.

  +---------------+---------------------------------------------------+
  |Names of the   |Illuminating power of a single Jet of Gas-flame    |
  |Places where   |four inches high, taken by a comparison of Shadows.|
  |Experiments    |         +-----------------------------------------+
  |were made.     |         |The Jet of Gas burnt, four inches high,  |
  |               |         |consumed per hour and was equal to the   |
  |               |         |Candles in the last column.              |
  |               |         |      +----------------------------------+
  |               |         |      |Gas required to be equal to 100   |
  |               |         |      |lbs. of mould Candles, 6 to the   |
  |               |         |      |lb., 9 inches long each.[A]       |
  |               |         |      |      +---------------------------+
  |               |         |      |      |Selling price of Gas per   |
  |               |         |      |      |meter per 1000 cubic feet. |
  +---------------+---------+------+------+-------+-------------------+
  |               |_Equal to|_Cubic|_Cubic|       |
  |               |Candles._|Feet._|Feet._|_s. d._|
  |Birmingham;   }|         |      |      |       |
  |Birmingham and}|         |      |      |       |
  |Staffordshire;}|  2·572  | 1·22 | 2704 |10   0 |
  |two Companies }|         |      |      |       |
  |Stockport      |  3·254  |  ·85 | 1489 |10   0 |
  |Manchester     |  3·060  |  ·825| 1536 | 8   0 |
  |Liverpool  Old}|         |      |      |       |
  |Company[C]    }|  2·369  | 1·1  | 2646 |10   0 |
  |Liverpool New} |         |      |      |       |
  |Gas Company  } |  4·408  |  ·9  | 1164 |10   0 |
  |Bradford       |  2·190  | 1·2  | 3123 | 9   0 |
  |Leeds          |  2·970  |  ·855| 1644 | 8   0 |
  |Sheffield      |  2·434  | 1·04 | 2440 | 8   0 |
  |Leicester      |  2·435  | 1·1  | 2575 | 7   6 |
  |Nottingham     |  1·645  | 1·3  | 4200 | 9   0 |
  |Derby          |  1·937  | 1·2  | 3521 |10   0 |
  |Preston        |  2·136  | 1·15 | 3069 |10   0 |
  |               |         |      |      |       |
  |London         |  2·083  | 1·13 | 3092 |10   0 |
  +---------------+---------+------+------+-------+

  +---------------+---------------------------------------------------+
  |Names of the   |Cost of Gas equal in illuminating power to 100 lbs.|
  |Places where   |of candles.[B]                                     |
  |Experiments    |          +----------------------------------------+
  |were made.     |          |Average discount allowed off the charge |
  |               |          |for Gas.                                |
  |               |          |        +-------------------------------+
  |               |          |        |Net cost of Gas equal to 100   |
  |               |          |        |lbs. of Candles.               |
  |               |          |        |          +--------------------+
  |               |          |        |          |Specific gravity of |
  |               |          |        |          |the Gas.            |
  +---------------+----------+--------+----------+----+---------------+
  |               |          | _Per_  |          |    |
  |               |_L. s. d._|_Cent._ |_L. s. d._|    |
  |Birmingham;   }|          |        |          |    |
  |Birmingham and}|          |        |          |    |
  |Staffordshire;}| 1  7  0  |  9     | 1  4  7  |·541|
  |two Companies }|          |        |          |    |
  |Stockport      | 0 14 11  | 12-1/2 | 0 13  0  |·539|
  |Manchester     | 0 12  3  | 11-1/4 | 0  0 10  |·534|
  |Liverpool  Old}|          |        |          |    |
  |Company[C]    }| 1  6  5  |  6-1/4 | 1  4  9  |·462|
  |Liverpool New} |          |        |          |    |
  |Gas Company  } | 0 11  8  |  6-1/4 | 0  9 10  |·580|
  |Bradford       | 1  8  1  | 12-1/2 | 1  4  6  |·420|
  |Leeds          | 0 13  2  |  6-1/4 | 0 12  4  |·530|
  |Sheffield      | 0 19  6  |  6-1/4 | 0 18  3  |·466|
  |Leicester      | 0 19  3  | 15     | 0 16  5  |·528|
  |Nottingham     | 1 17  9  | 15     | 1 11  3  |·424|
  |Derby          | 1 15  4  | 15     | 1 10  0  |·448|
  |Preston        | 1 10  8  | 15     | 1  6  2  |·419|
  |               |          |  none  |          |    |
  |London         | 1 10 11  |allowed.| 1 10 11  |·412|
  +---------------+----------+--------+----------+----+
  [A] 100 lbs. of candles are estimated to burn 5700 hours.
  [B] The candles cost 3_l._ 2_s._ 6_d._
  [C] The Liverpool Old Company have since resorted to the use of
      Cannel coal, and consequently very nearly assimilate to the
      Liverpool New Company in illuminating power.

  MEMORANDUM.--It will not fail to be observed that in deducing the
  comparative value between candles and gas by these experiments, the
  single jet (and in every instance, of course, it was the same), has
  been the medium. This however, though decidedly the most correct way
  of making the comparative estimate of the illuminating power of the
  several gases, is highly disadvantageous in the economical comparison,
  inasmuch as gas burnt in a properly regulated argand burner, with its
  proper sized glass, air aperture, and sufficient number of holes,
  gives an advantage in favour of gas consumed in an argand, over a jet
  burner, of from 30 to 40 per cent. At the same time it must not be
  overlooked that in many situations where great light is not required,
  it will be found far more economical to adopt the use of single jets,
  which by means of swing brackets and light elegant shades, becomes
  splendid substitutes for candles, in banking establishments, offices,
  libraries, &c. &c.

  NOTE.--In Glasgow, Edinburgh, Dundee, Perth, and the Scotch towns
  generally the Parrot or Scotch Cannel coal is used; in illuminating
  power and specific gravity the gas produced is equal to that from the
  best description of Cannel coal in England. The price per 1000 cubic
  feet ranges about 9_s._, with from 5 to 30 per cent. off for
  discounts, leaving the net price about 9_s._ to be equal in the above
  table to 100 lbs. of candles.

Epitome of Experiments made in Gas produced from different qualities of
Coal, and consumed in different kinds of Burners:

Tried at the Sheffield Gas Light Company’s Works, and laid before a
Committee of the House of Commons. By Joseph Hedley, Esq.

  +------+-----------+----------+--------+---------+--------+-------+
  |      |           |          |        |         |        |       |
  | Date |Description|Species of|Specific|Distance |Gas     |       |
  | 1835.|of Burner. |Coal.     |Gravity |of Candle|consumed|Height |
  |      |           |          |of Gas. |  from   |per     |of Gas |
  |      |           |          |        | Shadow. |Hour.   |Flame. |
  |      |           |          |        |         |        |       |
  |      |           |          |        |         |        |       |
  +------+-----------+----------+--------+---------+--------+-------+
  |      |           |          |        |         |_Cubic_ | _In-_ |
  |_May._|           |          |        |_Inches._|_Feet._ |_ches._|
  |  8   | Single Jet|Deep Pit  |  ·410  | 75      |  1·    |4      |
  |  9   | Ditto     |Mortormley|  ·450  | 74      |   ·95  |4      |
  |  9   | Ditto     |Cannel    |  ·660  | 61-1/4  |   ·7   |4      |
  |  8   |{ Argand  }|          |        |         |        |       |
  |      |{ 14 holes}|Deep Pit  |  ·410  | 34      |  3·3   |3-1/2  |
  |  9   | Ditto     |Mortormley|  ·450  | 33      |  3·1   |3-1/2  |
  |  9   | Ditto     |Cannel    |  ·660  | 29      |  2·6   |3-1/3  |
  +------+-----------+----------+--------+---------+--------+-------+

  +------+-------------+-----------+------------+----------+
  |      |Equal to     |           |            |Cost of   |
  | Date |Mould Tallow |Gas equal  |Cost of Gas |100 lbs.  |
  | 1835.|Candles, 6   |to 100 lbs.|at 8_s._    |of Mould  |
  |      |to the pound,|of Mould   |per 1000    |Candles   |
  |      |9 inches     | Candles.  |cubic feet. |at 7_s._  |
  |      |long each.   |           |            |6_d._ per |
  |      |             |           |            |dozen lbs.|
  +------+-------------+-----------+------------+----------+
  |      |             |  _Cubic_  |            |          |
  |_May._|  _Candles._ |  _Feet._  |_L. s.  d._ |_L. s. d._|
  |  8   |     2·36    |   2415    | 0 19 3-1/2}|          |
  |  9   |     2·434   |   2224    | 0 17 9-1/2}|          |
  |  9   |     3·54    |   1127    | 0  9 0    }|          |
  |  8   |             |           |           }| 3  2  6  |
  |      |    11·53    |   1631    | 0 13 0-1/2}|          |
  |  9   |    12·24    |   1443    | 0 11 6-1/2}|          |
  |  9   |    15·85    |    935    | 0  7 5-3/4}|          |
  +------+-------------+-----------+------------+----------+

Copy of Experiments made at the Alliance Gas Company’s Works in Dublin,
during the past year 1837. By Joseph Hedley, Esq.

Results of experiments on the qualities of various coals for the
production of gas; its value in illuminating power; produce of coke, and
quality; and other particulars important in gas-making:--

_1st Experiment, Saturday, May 27th, 1837._--Deane coal, (Cumberland). 2
cwt. of 112 lbs. each (or 224 lbs.) produced 970 cubic feet of gas; 4
bushels of coke of middling quality; specific gravity of the gas, 475.
Consumed in a single-jet burner, flame 4 inches high, 1-4/10ths cubic
feet per hour; distance from shadow 76 inches or 2·3 mould candles.
Average quantity of gas made from the charge (6 hours) 4·33 cubic feet
per lb., or 9,700 cubic feet per ton of 20 cwt. Increase of coke over
coal in measure, not quite 30 per cent. Loss in weight between coal,
coke and breize 56 lbs., converted into gas, tar, ammonia, &c.

_2nd Experiment, May 28th._--Carlisle coal, (Blenkinsopp). 224 lbs.
produced 1010 cubic feet of gas, 4 bushels of coke of good quality
though small; increase of coke over coal in measure not quite 30 per
cent. Loss in weight, same as foregoing experiment. Average quantity of
gas made from the charge (6 hours) 4·5 cubic feet per lb. or 10,080 per
ton.

_Illuminating power of the Gas._

  +-------------------------------+---------+--------+--------+--------+
  |                               |Consumed |Distance|Equal to|Specific|
  |                               |per hour,|from    |candles.|gravity.|
  |                               |single   |candle. |        |        |
  |                               |jet.     |        |        |        |
  +-------------------------------+---------+--------+--------+--------+
  |                               | _feet._ | _in-_  |        |        |
  |                               |         |_ches._ |        |        |
  |At the end of the 1st hour     |  1-1/10 |   70   |  2·72  |  ·475  |
  |Ditto    ditto    with 20-hole}|         |        |        |        |
  |argand burner                 }|  5      |   25   | 21·33  |  ·475  |
  |When charge nearly off         |  1-4/10 |   85   |  1·84  |  ·442  |
  |When charge quite off, with   }|         |        |        |        |
  |20-hole argand burner         }|  9      |  100   | not 1  |  ·256  |
  +-------------------------------+---------+--------+--------+--------+

_3rd Experiment, May 29th._--Carlisle coal (Blenkinsopp). 112 lbs.
produced 556 cubic feet of gas. Other products, loss of weight, &c.,
same proportion as foregoing experiment. Average quantity of gas made
from the charge (6 hours) 4·96 cubic feet per lb., or 11,120 per ton.

In this experiment the quantity of gas generated every hour was
ascertained; the illuminating power, the specific gravity, and the
quantity of gas consumed by the single jet with a flame 4 inches high,
was tried at the end of each hour, with the respective gases generated
at each hour; and the following is a table of results.

RESULTS.

  +-----+-------------+---------------+--------+---------+------------+
  |     |             |   Consumed    |Specific|Distance |Illuminating|
  |Hour.|Gas produced.|   per hour    |gravity.|of candle|power equal |
  |     |             |per single jet,|        |from     |  to mould  |
  |     |             | 4 inches high.|        |shadow.  |  candles.  |
  +-----+-------------+---------------+--------+---------+------------+
  |     |_cubic feet._| _cubic feet._ |        |  _in-_  |            |
  |     |             |               |        | _ches._ |            |
  |     |           { | 11-1/2-10ths.}|        |         |            |
  |1st. |    150    { |  or 1·15     }| ·534   |    70   |    2·72    |
  |     |             |               |        |         |            |
  |2nd. |    120      |    11         | ·495   |    75   |    2·36    |
  |3rd. |     95      |    12         | ·344   |    75   |    2·36    |
  |4th. |     95      |    15         | ·311   |    80   |    2·08    |
  |5th. |     80      |    17         | ·270   |    85   |    1·81    |
  |6th. |     16      |    29         | ·200   |   100   |   not one  |
  |     +-------------+---------------+                  |            |
  |Total|    556      | or 92-1/3 or 2 feet 9 inches.    |            |
  +-----+-------------+----------------------------------+------------+

                Average of the above gas, 6-hour charge.
              92-1/3      16-10ths.    ·359        81        2·03
                           nearly

               Average of the above gas at 4-hour charge.
             115          12-1/3-10ths. ·421        75        2·36

  Production of gas in 6 hours 556 feet, or at the rate of 11,120 cubic
                                                           feet per ton.
         Ditto      in 4 hours 460 feet, or at the rate of  9,200 ditto.

The relative value of these productions of gas is as follows, viz.:

11,120 at 16-10ths per hour nearly, (or 1·5916 accurately) and equal to
203 candles; the 11,120 feet would be equal to and last as long as 1597
candles, or 266-1/6 lbs. of candles.

9200 at 12-1/3-10ths. per hour, (or 1·2375 accurately,) and equal to 236
candles; the 9200 feet would be equal to 1949 candles, or 324-5/6 lbs.
candles.

  Now 266-1/6 lbs. of mould candles, at 7_s._ 6_d._ per dozen lbs.
  will cost  8_l._ 6_s._ 4-1/2_d._, whilst

      324-5/6 lbs. of  do.    do.    at 7_s._ 6_d._ per     do.
     do.    10_l._ 3_s._

Shewing the value of 4-hour charges, over 6-hour charges; and of 9,200
cubic feet over 11,120 cubic feet.

  Note.--9500 cubic feet of Wigan cannel coal gas are equal in
  illuminating power to 859 1-6th lbs. of candles, which at 7_s._ 6_d._
  per dozen lbs. will cost 25_l._ 10_s._ 5-1/2_d._ It is also found that
  any burner with superior gas, will consume only about half the
  quantity it would do with common gas.

_4th Experiment, May 30th._--Cannel and Cardiff coal mixed 1/2 and 1/2,
together 112 lbs., produced 460 feet of gas; 2 bushels of coke of good
quality; increase of coke over coal in measure about 30 per cent.; loss
in weight, 41 lbs.; coke weighed 71 lbs., no breize. Average quantity of
gas made from the charge, (4 hours) 4·1 cubic feet, per lb., or 9·200,
per ton.

_Illuminating power._--At end of first hour.

                        Candles.                            Cubic feet.
  Distance of candle}             {Consumed per hour, single}
  from shadow       }  73 or 2·49 {jet, 4 inches high       } 12-10ths

  At end of 2nd hour,  70 or 2·72     Do.     do.     do.   11-1/2-10ths
  do.

  At end of 3d hour.     This gas very indifferent.

  Average of the three 70 or 2·72     Do.     do.     do.   11-1/2-10ths

Specific gravity 3·44; 5 feet per hour, with a 20-hole argand burner,
equal to 14·66 candles.

_5th Experiment, May 31st._--Carlisle coal, 112 lbs. produced 410 feet
of gas; other products, same as in former experiments with this coal,
but heat very low.

_Illuminating power and produce of gas._

                                  {Average of this gas: specific gravi-
         {1st hour 120 cubic feet {ty, 540; distance of candle from
         {2nd      100            {shadow, 55 inches, or 4·4 candles
  410 ft {3d        90            {consumed per single jet, 9-10ths of a
         {4th      100            {cubic foot per hour. 20-hole argand
                                  {burner, 4 feet per hour, equal to
                                  {21·33 candles.

It is possible, from the superior quality of this gas, that a little of
the cannel gas made for a particular purpose, may have have got
intermixed with it in the experimental gasholder and apparatus.

A variety of other experiments were tried on different qualities of
coal, and mixtures of ditto, too tedious to insert here, though
extremely valuable, and all tending to shew the superior value of gas
produced at short over long charges; and also showing the importance and
value of coal producing gas of the highest illuminating power; among
which the cannel coal procured in Lancashire, Yorkshire, and some other
counties of England and Wales, and the Parrot or splent coal of
Scotland, stand pre-eminent.

  Note.--In all the foregoing experiments the same single-jet burner was
  used; its flame in all instances exactly 4 inches high.

  The coal when drawn from the retort was slaked with water, and after
  allowing some short time for drying, was weighed.

A TABLE of the number of hours Gas is burnt in each month, quarter and
year.

  +---------------+-----+----+----+----+----+----+----+----+----+----+
  |Time of        |July.|Aug.|Sep.|Oct.|Nov.|Dec.|Jan.|Feb.|Mar.|Apl.|
  |Burning.       |     |    |    |    |    |    |    |    |    |    |
  |               |     |    |    |    |    |    |    |    |    |    |
  +---------------+-----+----+----+----+----+----+----+----+----+----+
  |       o’clock.|     |    |    |    |    |    |    |    |    |    |
  |From Dusk to  6|  -- |  --|   2|  31|  62|  80|  65|  33|   4|  --|
  |     --       7|  -- |  14|  22|  62|  92| 111|  96|  61|  31|   4|
  |     --       8|  -- |  40|  52|  93| 122| 142| 127|  89|  62|  28|
  |     --       9|  13 |  71|  82| 124| 152| 173| 158| 117|  93|  58|
  |     --      10|  44 | 102| 112| 155| 182| 204| 189| 145| 124|  88|
  |     --      11|  75 | 133| 142| 186| 212| 235| 220| 173| 155| 118|
  |     --      12| 106 | 164| 172| 217| 242| 266| 251| 201| 186| 148|
  |All night     -| 217 | 307| 345| 421| 473| 527| 512| 411| 382| 295|
  |Morning from  4|  -- |  16|  48|  80| 110| 137| 137|  98|  71|  28|
  |     --       5|  -- |  --|  18|  49|  80| 106| 106|  70|  40|   3|
  |     --       6|  -- |  --|  --|  18|  50|  75|  75|  42|   9|  --|
  |     --       7|  -- |  --|  --|  --|  20|  44|  44|  14|  --|  --|
  +---------------+-----+----+----+----+----+----+----+----+----+----+

  +---------------+----+-----++-----+-----+-----+-----+-----+----+
  |Time of        |May.|June.||Mid. |Mic. |Xms. |Lady |Totl.|    |
  |Burning.       |    |     ||quar.|quar.|quar.|day  | of  |    |
  |               |    |     ||     |     |     |quar.|Year.|    |
  +---------------+----+-----++-----+-----+-----+-----+-----+----+
  |       o’clock.|    |     ||     |     |     |     |     |    |
  |From Dusk to  6|  --|  -- ||  -- |   2 | 173 | 102 | 277 |}   |
  |     --       7|  --|  -- ||   4 |  36 | 265 | 188 | 493 |}   |
  |     --       8|   4|  -- ||  32 |  92 | 357 | 278 | 759 |}   |
  |     --       9|  29|   8 ||  95 | 166 | 449 | 368 |1078 |}   |
  |     --      10|  60|  38 || 186 | 258 | 541 | 458 |1443 |}   |
  |     --      11|  91|  68 || 277 | 350 | 633 | 548 |1808 |}[A]|
  |     --      12| 122|  98 || 368 | 442 | 725 | 638 |2173 |}   |
  |All night     -| 242| 195 || 732 | 869 |1421 |1305 |4327 |}   |
  |Morning from  4|   2|  -- ||  30 |  64 | 327 | 306 | 727 |}   |
  |     --       5|  --|  -- ||   3 |  18 | 235 | 216 | 472 |}   |
  |     --       6|  --|  -- ||  -- |  -- | 143 | 126 | 269 |}   |
  |     --       7|  --|  -- ||  -- |  -- |  64 |  58 | 122 |}   |
  +---------------+----+-----++-----+-----+-----+-----+-----+----+
  [A] For Sundays off, deduct one seventh.

Copy of a Paper submitted to a Committee of the House of Commons in the
Session of 1837, being a Synopsis of the proceedings of the
undermentioned principal Gas-Light Establishments of England; and
procured by actual Survey and Experiments between the Years 1834 and
1837. By Joseph Hedley, Esq.

  +--------------+------------------------------+------------------+--------+
  |Name of the   |Price of Gas per Meter, and   |Price of Coal, and|Average |
  |Place where   |Discounts allowed.            |Description; de-  |Quantity|
  |Gas Works     |                              |livered per Ton.  |of Gas  |
  |are situated. |                              |                  |made per|
  |              |                              |                  |Ton of  |
  |              |                              |                  |Coals.  |
  +--------------+------------------------------+------------------+--------+
  |              |                              |                  |_Cu.    |
  |              |                              |                  |ft._    |
  +--------------+------------------------------+------------------+--------+
  |Birmingham Gas|10_s._ per meter cub. feet.   |Lump coal from    |6,500   |
  |Company.      |          Discounts           |West Bromwich pits|        |
  |              |     per an.       per cent.  |risen much of     |        |
  |              | 10_l._ to  30_l._   2-1/2    |late. 1837, 11_s._|        |
  |              | 30_l._ to  50_l._   5        |10_d._            |        |
  |              | 50_l._ to  75_l._   7-1/2    |                  |        |
  |              | 75_l._ to 100_l._  10        |                  |        |
  |              |100_l._ & upwards   15        |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Birmingham and|10_s._ per meter cub. feet.   |From West Bromwich|6,500   |
  |Staffordshire.|Discounts as above.           |pits, 1837, 9_s._ |        |
  |              |                              |3_d._             |        |
  +--------------+------------------------------+------------------+--------+
  |Macclesfield. |10_s._ per meter cub. feet.   |Common, 8_s._     |6,720   |
  |              |         Discounts            |average 1831      |        |
  |              |Above   and not   per cent.   |                  |        |
  |              |        exceeding             |                  |        |
  |              | 50_l._   75_l._    5         |                  |        |
  |              | 75_l._  100_l._    7-1/2     |                  |        |
  |              |100_l._  125_l._   10         |                  |        |
  |              |125_l._  150_l._   12-1/2     |                  |        |
  |              |150_l._  175_l._   15         |                  |        |
  |              |175_l._  200_l._   17-1/2     |                  |        |
  |              |200_l._ & upwards  20.        |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Stockport.    |10_s._ per meter cub. feet.   |Coal 10_s._ 6_d._ |7,800   |
  |              |Discounts same as Maccles-    |cannel 19_s._     |        |
  |              |field. Macclesfield discounts |6_d._ about half  |        |
  |              |taken from Stockport card.    |and half used.    |        |
  |              |                              |Average 15_s._    |        |
  |              |                              |1834.             |        |
  +--------------+------------------------------+------------------+--------+
  |Manchester.   |10_s._ per m. cub. ft. 1834.  |15_s._ 2_d._      |9,500   |
  |              | 9_s._ and 8_s._  --   1837.  |average.          |        |
  |              |       Discounts              |Oldham    }       |        |
  |              |          and under  per cent.|Watergate }cannel.|        |
  |              | 50_l._    100_l._   2-1/2    |Wigan     }       |        |
  |              |100_l._    150_l._   5        |Mixed, 1834.      |        |
  |              |150_l._    200_l._   7-1/2    |                  |        |
  |              |200_l._    225_l._  10        |                  |        |
  |              |225_l._    250_l._  12-1/2    |                  |        |
  |              |250_l._    300_l._  15        |                  |        |
  |              |300_l._    400_l._  17-1/2    |                  |        |
  |              |400_l._ and upwards 20        |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Liverpool Old |10_s._ per meter cub. feet.   |7_s._ 3_d._ per   |8,200   |
  |Company, 1834.|     Discounts         per ct.|ton of 112 lbs.   |        |
  |              | 10_l._ & under  50_l._  2-1/2|per cwt. Ormskirk |        |
  |              | 50_l._   to    100_l._  5    |or Wigan slack.   |        |
  |              |100_l._   to    200_l._  7-1/2|                  |        |
  |              |300_l._ & upwards       10    |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Ditto ditto.  |In 1835 this Company resorted to the use of cannel coal   |
  |              |similar to the Liverpool New Gas and Coal Company, pro-   |
  |              |ducing nearly similar results, which see.                 |
  +--------------+------------------------------+------------------+--------+
  |Liverpool New |10_s._ per meter cub. feet.   |18_s._ all cannel |9,500   |
  |Gas and Coke, |Discounts same as Liverpool   |Wigan.            |        |
  |1835.         |Old Company.                  |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Bradford,     |9_s._ per meter cubic feet to |8_s._ 6_d._ per   |8,000   |
  |1834.         |large consumers.              |ton. 3 sorts used |        |
  |              |    Discounts    per cent.    |average. Slack    |        |
  |              | 20_l._ to  30_l._  5         |5_s._ 6_d._ Low   |        |
  |              | 30_l._ to  40_l._  7-1/2     |moor 8_s._ 10_d._ |        |
  |              | 40_l._ to  60_l._ 10         |Catherine slack   |        |
  |              | 60_l._ to  80_l._ 12-1/2     |8_s._             |        |
  |              | 80_l._ to 100_l._ 15         |                  |        |
  |              |100_l._ & upwards  20         |                  |        |
  |              |Small consumers, 10_s._ per   |                  |        |
  |              |meter cub. feet, and 5 per    |                  |        |
  |              |cent. off from 10_l._ to      |                  |        |
  |              |20_l._                        |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Leeds, 1834.  |8_s._ per meter cubic feet.   |8_s._ per ton av- |6,500   |
  |              |       Discounts              |erage. 2-3ds com- |        |
  |              | 2-1/2}per cent.{  15_l._     |mon 7_s._ 1-3d    |        |
  |              | 5    }on half- {  30_l._     |cannel, 10_s._    |        |
  |              | 7-1/2}yearly   {  50_l._     |                  |        |
  |              |10    }payments { 100_l._     |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Sheffield,    |8_s._ per meter cubic feet.   |7_s._ 9_d._ per   |8,000   |
  |1835.         |Discounts same as Leeds.      |ton average. 3    |        |
  |              |                              |sorts used 1,     |        |
  |              |                              |2-10ths. cannel,  |        |
  |              |                              |at 16_s._ 8,      |        |
  |              |                              |2-10ths. deep pit,|        |
  |              |                              |7_s._ 1-10th silk |        |
  |              |                              |stone, 10_s._     |        |
  +--------------+------------------------------+------------------+--------+
  |Leicester,    |7_s._ 6_d._ per meter cub. ft.|13_s._ 6_d._ aver-|7,500   |
  |1837.         |Discounts on half-yearly      |age. Derbyshire   |        |
  |              |rental not exceeding 10_l._,  |soft coal.        |        |
  |              |5 per cent.                   |                  |        |
  |              |Above   and not    per cent.  |                  |        |
  |              |       exceeding              |                  |        |
  |              |10_l._     20_l._    7-1/2    |                  |        |
  |              |20_l._     30_l._   10        |                  |        |
  |              |30_l._     40_l._   12-1/2    |                  |        |
  |              |40_l._     50_l._   15        |                  |        |
  |              |50_l._     60_l._   20        |                  |        |
  |              |60_l._ & upwards    25        |                  |        |
  +--------------+------------------------------+------------------+--------+
  |Derby, 1834.  |10_s._ per meter cub. feet.   |Same coal used as |7,000   |
  |              |Discounts 5 to 35 per cent.   |at Leicester.     |        |
  +--------------+------------------------------+------------------+--------+
  |Nottingham,   |9_s._ per meter cubic feet.   |Ditto.            |7,000   |
  |1834.         |Discounts as above.           |                  |        |
  +--------------+------------------------------+------------------+--------+
  |London, 1834. |10_s._ per meter cub. feet. No|17_s._ average.   |8,500   |
  |              |discounts.                    |Newcastle.        |        |
  +--------------+------------------------------+------------------+--------+
  |Ditto, 1837.  |Ditto.                        |Ditto.            |8,500   |
  +--------------+------------------------------+------------------+--------+

  +--------------+-----------+-------------+---------+--------+-------------+
  |Name of the   |Coke made  |Selling Price|Material |Quantity|No. of Public|
  |Place where   |from a Ton |of Coke.     |used to  |used per|or Street    |
  |Gas Works     |of Coal.   |             |heat Re- |Ton of  |Lamps        |
  |are situated. |           |             |torts.   |Coal.   |supplied.    |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Birmingham Gas|32 bushels.|2_s._ 1_d._  |Slack.   |About 5 |  490        |
  |Company.      |           |per quarter  |         |cwt. of |             |
  |              |           |delivered, or|         |slack,  |             |
  |              |           |about 3_d._  |         |at 6_s._|             |
  |              |           |per bushel.  |         |per ton,|             |
  |              |           |             |         |25 per  |             |
  |              |           |             |         |cent.   |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Birmingham and|24 bush.   |2_s._ 10_d._ |Slack and|5 cwt.  |1,500        |
  |Staffordshire.|but larger |per sack of 8|Tar.     |of      |             |
  |              |measure    |bushels.     |         |slack,  |             |
  |              |than Bir-  |             |         |at 4_s._|             |
  |              |mingham.   |             |         |25 per  |             |
  |              |           |             |         |cent.   |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Macclesfield. |12 cwt.    |10_s._ per   |Coke.    |No ac-  |  220        |
  |              |           |ton.         |         |count   |             |
  |              |           |             |         |kept.   |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Stockport.    |7 cwt.     |6_s._ 8_d._  |Coal,    |Ditto.  |  230        |
  |              |           |per ton.     |coke, and|        |             |
  |              |           |             |tar.     |        |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Manchester.   |14 cwt.    |Ditto.       |Coke.    |4, 2-3ds|2,375        |
  |              |           |             |         |cwt.    |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Liverpool Old |11-3/4 cwt.|8_s._ 4_d._  |Slack    |6-1/2   |1,700 30     |
  |Company, 1834.|           |per ton of   |7_s._    |cwt.    |             |
  |              |           |112 lb. per  |3_d._    |        |             |
  |              |           |cwt.         |per ton. |        |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Ditto ditto.  |In 1835 this Company resorted to the use of cannel coal   |
  |              |similar to the Liverpool New Gas and Coal Company, pro-   |
  |              |ducing nearly similar results, which see.                 |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Liverpool New |13 cwt.    |7_s._ 6_d._  |Coke and |5-1/2   |Only a few.  |
  |Gas and Coke, |           |per ton.     |slack.   |cwt.    |             |
  |1835.         |           |             |         |        |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Bradford,     |13 cwt.    |12_s._ per   |Coke.    |8-1/2   |220          |
  |1834.         |           |ton.         |         |cwt.    |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Leeds, 1834.  |12 cwt.    |7_s._ 6_d._  |Ditto.   |5-1/4   |517          |
  |              |           |per ton.     |         |cwt.    |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Sheffield,    |10 cwt. of |10_s._ per   |Ditto.   |3-1/2   |600          |
  |1835.         |saleable   |ton.         |         |cwt.    |             |
  |              |coke.      |             |         |        |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Leicester,    |4 quarters.|10_s._ 8_d._ |Coke     |About   |414          |
  |1837.         |           |or 2_s._     |tar, &c. |1-3d of |             |
  |              |           |8_d._ per qr.|         |coke.   |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Derby, 1834.  |Ditto.     |Ditto.       |Coke.    |Ditto.  |219          |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Nottingham,   |Ditto.     |Ditto.       |Ditto.   |Ditto.  |300          |
  |1834.         |           |             |         |        |             |
  +--------------+-----------+-------------+---------+--------+-------------+
  |London, 1834. |36 bush.   |12_s._ per   |Ditto.   |13 bush.|26,280       |
  +--------------+-----------+-------------+---------+--------+-------------+
  |Ditto, 1837.  |Ditto.     |Ditto.       |Ditto.   |Ditto.  |30,400       |
  +--------------+-----------+-------------+---------+--------+-------------+

  +--------------+------------+----------+--------------+-------------------+
  |Name of the   |Description.|Price paid|Who lights,   |No. of Hours, or   |
  |Place where   |----        |per Annum |cleans, puts  |Time burnt in the  |
  |Gas Works     |Size or     |for Ditto.|out, and re-  |Year.              |
  |are situated. |Sort.       |          |pairs.        |                   |
  +--------------+------------+----------+--------------+-------------------+
  |              |            |_L. s. d._|              |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Birmingham Gas|Batswings,  |          |Company, and  |226 nights, or 2938|
  |Company.      |460         | 1 10  0  |provides      |hours, 9 months,   |
  |              |30          | 2  0  0  |posts, ser-   |omitting 5 nights  |
  |              |            |          |vices, &c.    |for moons.         |
  +--------------+------------+----------+--------------+-------------------+
  |Birmingham and|Batswings.  |average   |Ditto.        |234 nights, or 3042|
  |Staffordshire.|            | 1 18  0  |              |hours.             |
  +--------------+------------+----------+--------------+-------------------+
  |Macclesfield. |Ditto.      | 2 10  0  |Company.      |8 months, omitting |
  |              |            |          |              |5 nights for moons.|
  +--------------+------------+----------+--------------+-------------------+
  |Stockport.    |Ditto.      | 2 10  0  |Comrs. provide|8 months. 4 nights |
  |              |            |  1834.   |lamps and     |omitted for moons. |
  |              |            | 2  0  0  |posts. Compa- |237 nights--2800   |
  |              |            |  1837.   |ny’s service  |hours.             |
  |              |            |          |light, repair,|                   |
  |              |            |          |clean, and ex-|                   |
  |              |            |          |tinguish.     |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Manchester.   |Single-jets | 1  2  0  |Commissioners |3390 hours.        |
  |              |and flat    | 2  0  0  |of police.    |                   |
  |              |flames,     |          |              |                   |
  |              |about half  |          |              |                   |
  |              |and half.   |          |              |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Liverpool Old |Batswings,  | 4 10  0  |Company light,|3600 hours.        |
  |Company, 1834.|1 jet,      | 2  5  0  |clean, put    |                   |
  |              |2  --       | 2 13  0  |out, and re-  |                   |
  |              |3  --       | 3  2  9  |pair.         |                   |
  |              |4  --       | 3 13 11  |              |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Ditto ditto.  |In 1835 this Company resorted to the use of cannel coal   |
  |              |similar to the Liverpool New Gas and Coal Company, pro-   |
  |              |ducing nearly similar results, which see.                 |
  +--------------+------------+----------+--------------+-------------------+
  |Liverpool New |Argands.    | 4  0  0  |Commissioners.|3000 hours.        |
  |Gas and Coke, |            |          |              |                   |
  |1835.         |            |          |              |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Bradford,     |Batswings.  | 2 12  6  |Company light,|8 months, omitting |
  |1834.         |            |          |repair, &c.   |7 nights, 2600     |
  |              |            |          |              |hours to 4 o’clock |
  |              |            |          |              |in the morning.    |
  +--------------+------------+----------+--------------+-------------------+
  |Leeds, 1834.  |Ditto.      | 2 12  6  |Commissioners,|2330 hours.        |
  |              |            |          |except extin- |                   |
  |              |            |          |guishing, for |                   |
  |              |            |          |which Company |                   |
  |              |            |          |pay 3_s._     |                   |
  |              |            |          |10_d._ per    |                   |
  |              |            |          |lamp.         |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Sheffield,    |Ditto.      | 2 10  0  |Company pro-  |2200 hours.        |
  |1835.         |            |          |vide lamps,   |                   |
  |              |            |          |clean, repair,|                   |
  |              |            |          |put out, &c.  |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Leicester,    |Ditto.      | 2 18  6  |Company light,|From August 14th to|
  |1837.         |            |          |put out, and  |September 1st,     |
  |              |            |          |clean.        |omitting 3 nights  |
  |              |            |          |              |for moons, 3000    |
  |              |            |          |              |hours.             |
  +--------------+------------+----------+--------------+-------------------+
  |Derby, 1834.  |Ditto.      | 2  2  0  |Commissioners |2173 hours, from   |
  |              |            | 2  7  0  |light, put    |August to May.     |
  |              |            |          |out, &c.      |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Nottingham,   |Ditto.      | 3  3  0  |Commissioners |All the year, 4327 |
  |1834.         |            |          |light, clean, |hours.             |
  |              |            |          |repair, &c.   |                   |
  +--------------+------------+----------+----------------------------------+
  |London, 1834. |Ditto.      | 4  0  0  |Company light,|4327 hours, all the|
  |              |            |          |clean, put    |year.              |
  |              |            |          |out, but not  |                   |
  |              |            |          |repair.       |                   |
  +--------------+------------+----------+--------------+-------------------+
  |Ditto, 1837.  |Ditto.      | 4  0  0  |Ditto.        |Ditto.             |
  +--------------+------------+----------+--------------+-------------------+

  +--------------+------------+---------+----------+------------------------+
  |Name of the   |Gas consumed|Rate per |Amount de-|Per Centage of Loss of  |
  |Place where   |in each Lamp|Meter Cu-|ducted for|Gas made.               |
  |Gas Works     |per Hour.   |bic Feet |cleaning, |                        |
  |are situated. |            |received |lighting, |                        |
  |              |            |for      |extin-    |                        |
  |              |            |Ditto.   |guishing, |                        |
  |              |            |         |providing |                        |
  |              |            |         |Lamp      |                        |
  |              |            |         |Posts; &c.|                        |
  +--------------+------------+---------+----------+------------------------+
  |              |            |_s. d._  |_s. d._   |                        |
  +--------------+------------+---------+----------+------------------------+
  |Birmingham Gas|5 feet per  |30 10    |18  0     |Receives net about 6_s._|
  |Company.      |hour.       |40 18    |          |8_d._ per meter cubic   |
  |              |            |         |          |feet.                   |
  +--------------+------------+---------+----------+------------------------+
  |Birmingham and|Ditto.      | 1  3-1/2|18  0     |Receives net about 5_s._|
  |Staffordshire.|            |         |          |6_d._ per  meter cubic  |
  |              |            |         |          |feet.                   |
  +--------------+------------+---------+----------+------------------------+
  |Macclesfield. |4 feet per  | 3  0    |12  0     |Could not say.          |
  |              |hour.       |         |          |                        |
  +--------------+------------+---------+----------+------------------------+
  |Stockport.    |Ditto.      | 2  6    |12  6     |Ditto.                  |
  +--------------+------------+---------+----------+------------------------+
  |Manchester.   |1 foot,     | 6  6    |nothing.  |About 15 to 17-1/2 per  |
  |              |2 feet, per | 5  6    |          |cent. receive about     |
  |              |hour.       |         |          |7_s._ 4_d._ per meter   |
  |              |            |         |          |cubic feet, public and  |
  |              |            |         |          |private. Nearly all by  |
  |              |            |         |          |meter.                  |
  +--------------+------------+---------+----------+------------------------+
  |Liverpool Old |5 feet per  | 4  4    |12  0     |Could not learn in the  |
  |Company, 1834.|hour.       |         |          |absence of the manager. |
  +--------------+------------+---------+----------+------------------------+
  |Ditto ditto.  |In 1835 this Company resorted to the use of cannel coal   |
  |              |similar to the Liverpool New Gas and Coal Company, pro-   |
  |              |ducing nearly similar results, which see.                 |
  +--------------+------------+---------+----------+------------------------+
  |Liverpool New |3-1/2 feet  | 5  6    |nothing.  |Nearly all by meter.    |
  |Gas and Coke, |per hour.   |         |          |                        |
  |1835.         |            |         |          |                        |
  +--------------+------------+---------+----------+------------------------+
  |Bradford,     |5 feet per  | 3  1    |12  6     |Receive 8_s._ per meter |
  |1834.         |hour.       |         |          |cubic feet, less 5-1/2  |
  |              |            |         |          |per cent.               |
  +--------------+------------+---------+----------+------------------------+
  |Leeds, 1834.  |4 feet per  | 5  2    | 3 10     |Receive for public and  |
  |              |hour.       |         |          |private 6_s._ 8_d._ per |
  |              |            |         |          |meter cubic feet. Public|
  |              |            |         |          |5_s._, private 7_s._;   |
  |              |            |         |          |meters used to 5 to 1   |
  |              |            |         |          |for private rental.     |
  +--------------+------------+---------+----------+------------------------+
  |Sheffield,    |Ditto.      | 3  2-1/2|18  0     |Receive for public and  |
  |1835.         |            |         |          |private lts. 5_s._ per  |
  |              |            |         |          |meter cubic feet. Public|
  |              |            |         |          |3_s._ 2-1/2_d._, private|
  |              |            |         |          |5_s._ 9-1/2_d._ Few     |
  |              |            |         |          |meters used.            |
  +--------------+------------+---------+----------+------------------------+
  |Leicester,    |5 feet per  | 3  4-3/4| 7  0     |Not sufficiently long,  |
  |1837.         |hour.       |         |          |at 7_s._ 6_d._          |
  +--------------+------------+---------+----------+------------------------+
  |Derby, 1834.  |Ditto.      | 4  0    |  ----    |Lose about 17-1/2 per   |
  |              |            |nearly.  |          |cent.                   |
  +--------------+------------+---------+----------+------------------------+
  |Nottingham,   |Ditto.      | 3  0    |  ----    |Could not learn.        |
  |1834.         |            |nearly.  |          |                        |
  +--------------+------------+---------+----------+------------------------+
  |London, 1834. |4 feet per  | 4  0    |12  0     |Receive for public and  |
  |              |hour.       |         |          |private lights 7_s._    |
  |              |            |         |          |public, 4_s._ private,  |
  |              |            |         |          |8_s._ few  meters used. |
  +--------------+------------+---------+----------+------------------------+
  |Ditto, 1837.  |Ditto.      | 4  0    |12  0     |Ditto.                  |
  +--------------+------------+---------+----------+------------------------+

  +--------------+--------------+--------+---------+---------+--------+
  |Name of the   |Greatest Quan-|Duration|Method of|Number of|Specific|
  |Place where   |tity of Gas   |of Char-|Purifica-|Gas      |Gravity |
  |Gas Works     |delivered in  |ges.    |tion.    |Holders. |of the  |
  |are situated. |One Night.    |        |         |         |Gas.    |
  |              |              |        |         |         |        |
  |              |              |        |         |         |        |
  |              |              |        |         |         |        |
  |              |              |        |         |         |        |
  |              |              |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+
  |              |_Cubic Feet._ |        |         |         |        |
  +--------------+--------------+--------+----------+--------+--------+
  |Birmingham Gas|48 millions in|6 hours.|Dry lime.|4, and 2 |·453    |
  |Company.      |the year.     |        |         |in the   |        |
  |              |              |        |         |town, and|        |
  |              |              |        |         |large new|        |
  |              |              |        |         |gas      |        |
  |              |              |        |         |station. |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Birmingham and|85 millions in|Ditto.  |Ditto.   |6, and 6 |·455    |
  |Staffordshire.|the year.     |        |         |in the   |        |
  |              |              |        |         |town 7   |        |
  |              |              |        |         |miles    |        |
  |              |              |        |         |off.     |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Macclesfield. |80,000. Total |8 hours.|Ditto.   |3 gas    |Not     |
  |              |for year about|        |         |holders. |taken.  |
  |              |15 millions.  |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Stockport.    |65,000. Total |Ditto.  |Ditto.   |4 gas    |·539    |
  |              |for year about|        |         |holders. |        |
  |              |12 millions.  |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Manchester.   |500,000. Total|6 hours.|Wet lime.|10 gas   |·534    |
  |              |for year 100  |        |         |holders, |        |
  |              |millions.     |        |         |and 2 in |        |
  |              |              |        |         |the town.|        |
  +--------------+--------------+--------+---------+---------+--------+
  |Liverpool Old |360,000. Total|8 hours,|Wet and  |8 gas    |·462    |
  |Company, 1834.|for year      |large   |dry lime,|holders  |        |
  |              |72 millions.  |retorts |princi-  |in all, 4|        |
  |              |              |holding |pally    |in the   |        |
  |              |              |6 cwt.  |dry.     |town,    |        |
  |              |              |each.   |         |1000     |        |
  |              |              |        |         |yards    |        |
  |              |              |        |         |off the  |        |
  |              |              |        |         |works.   |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Ditto ditto.  |In 1835 this Company resorted to the use of cannel  |
  |              |coal similar to the Liverpool New Gas and Coal Com- |
  |              |pany, producing nearly similar results, which see.  |
  +--------------+--------------+--------+---------+---------+--------+
  |Liverpool New |Not suffi-    |4 hours.|Wet lime.|2 large  |·580    |
  |Gas and Coke, |ciently long  |        |         |gas      |        |
  |1835.         |at work.      |        |         |holders. |        |
  +--------------+--------------+------------------+---------+--------+
  |Bradford,     |42,500. Total |8 hours.|Dry lime.|4 gas    |·420    |
  |1834.         |for year      |        |         |holders. |        |
  |              |8,619,000.    |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Leeds, 1834.  |176,000. Total|6 hours.|Ditto.   |5 gas    |·530    |
  |              |for year 31   |        |         |holders. |        |
  |              |millions.     |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Sheffield,    |220,000. Total|Ditto.  |Ditto.   |4 gas    |·466    |
  |1835.         |for year 40   |        |         |holders, |        |
  |              |millions.     |        |         |and 2    |        |
  |              |              |        |         |more     |        |
  |              |              |        |         |erecting.|        |
  +--------------+--------------+--------+---------+---------+--------+
  |Leicester,    |Total for year|Ditto.  |Ditto.   |3 gas    |·528    |
  |1837.         |18 millions.  |        |         |holders, |        |
  |              |              |        |         |and 1    |        |
  |              |              |        |         |erecting.|        |
  +--------------+--------------+--------+---------+---------+--------+
  |Derby, 1834.  |Ditto.        |Ditto.  |Wet lime.|4 gas    |·448    |
  |              |              |        |         |holders. |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Nottingham,   |Ditto.        |Ditto.  |Ditto.   | ----    |·424    |
  |1834.         |              |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+
  |London, 1834. |Total for year|Ditto.  |Ditto.   |130 gas  |·412    |
  |              |1000 millions.|        |         |holders. |        |
  |              |Longest night |        |         |         |        |
  |              |4,910,000.    |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+
  |Ditto, 1837.  |Total for year|Ditto.  |Ditto.   |176 gas  |·412    |
  |              |1460 millions.|        |         |holders. |        |
  |              |Longest night |        |         |         |        |
  |              |7,120,000.    |        |         |         |        |
  +--------------+--------------+--------+---------+---------+--------+

  +--------------+---------+-----------+--------+-------+-------------+
  |Name of the   |Distance |Gas equal  |Gas     |Gas    |Height of Gas|
  |Place where   |of Candle|to Candles.|consumed|Flame  |Flame equal  |
  |Gas Works     |from     |Gas burnt  |per Hour|reduced|to Light     |
  |are situated. |Shadow.  |in a single|with a  |to Can-|from Candle. |
  |              |         |Jet Four   |Four-   |dle    |             |
  |              |         |Inches     |Inch    |burnt  |             |
  |              |         |high.      |Flame.  |per    |             |
  |              |         |           |        |Hour.  |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |              |_Inch._  |_Candles_  |_Cu.    |_Cu.   |_Inch._      |
  |              |         |           |ft._    |ft._   |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Birmingham Gas|72       |1,929      |1·22    | ·8    |2-1/2        |
  |Company.      |         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Birmingham and|72       |1,929      |1·22    | ·8    |2-1/2        |
  |Staffordshire.|         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Macclesfield. |70       |  204      |Not     | ·8    |2-3/4        |
  |              |         |           |taken.  |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Stockport.    |64       |2,441      | ·85    | ·55   |2-5/8        |
  +--------------+---------+-----------+--------+-------+-------------+
  |Manchester.   |66       |2,295      | ·825   | ·475  |2-1/4        |
  +--------------+---------+-----------+--------+-------+-------------+
  |Liverpool Old |75       |1,777      |1·1     | ·75   |2-5/8        |
  |Company, 1834.|         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Ditto ditto.  |In 1835 this Company resorted to the use of cannel  |
  |              |coal similar to the Liverpool New Gas and Coal Com- |
  |              |pany, producing nearly similar results, which see.  |
  +--------------+---------+-----------+--------+-------+-------------+
  |Liverpool New |55       |3,306      | ·9     | ·45   |2            |
  |Gas and Coke, |         |           |        |       |             |
  |1835.         |         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Bradford,     |78       |1,643      | ·12    | ·9    |3            |
  |1834.         |         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Leeds, 1834.  |67       |2,228      | ·855   | ·51   |2-1/4        |
  +--------------+---------+-----------+--------+-------+-------------+
  |Sheffield,    |74       |1,826      |1·04    | ·735  |2-3/4        |
  |1835.         |         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Leicester,    |74       |1,826      |1·1     | ·75   |2-3/4        |
  |1837.         |         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |Derby, 1834.  |83       |1,453      |1·2     | ·925  |3            |
  +--------------+---------+-----------+--------+-------+-------------+
  |Nottingham,   |90       |1,234      |1·3     |1·175  |3            |
  |1834.         |         |           |        |       |             |
  +--------------+---------+-----------+--------+-------+-------------+
  |London, 1834. |80       |1,562      |1·13    | ·84   |2-3/4        |
  +--------------+---------+-----------+--------+-------+-------------+
  |Ditto, 1837.  |80       |1,562      |1·13    | ·84   |2-3/4        |
  +--------------+---------+-----------+--------+-------+-------------+

A TABLE shewing the Rate per Thousand Cubic feet received for any Burner
consuming from 1/2 a Cubic foot to 10 Cubic feet per hour, at any given
price per annum, and to the times below stated. By Joseph Hedley, Esq.

  +----------------------+------+-----------------+-----------------+
  |                      |      |  Single Jets.   |    2  Jets.     |
  |                      |      |                 |                 |
  |                      | No.  +-----+-----+-----+-----+-----+-----+
  |   Time of Burning    | of   | Cub.| Cub.| Cub.|Cub. |Cub. |Cub. |
  |      per annum.      |Hours.| ft. | ft. | ft. | ft. | ft. | ft. |
  |                      |[30]  | 1/2 | 3/4 |  1  |1-1/4|1-1/2|1-3/4|
  +----------------------+------+-----+-----+-----+-----+-----+-----+
  |From Dusk to 8 o’clock|  781 |2·56 |1·706|1·28 |1·026|·853 |·731 |
  |     ditto and Sundays|  902 |2·216|1·478|1·108| ·887|·739 |·633 |
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1050 |1·904|1·27 | ·952| ·762|·635 |·544 |
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 1172 |1·706|1·138| ·853| ·682|·569 |·487 |
  |   9 o’clock          | 1054 |1·896|1·264| ·948| ·759|·632 |·542 |
  |     ditto and Sundays| 1221 |1·638|1·092| ·819| ·675|·546 |·463 |
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1323 |1·510|1·066| ·755| ·604|·503 |·431 |
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 1490 |1·342| ·894| ·671| ·536|·447 |·383 |
  |  10 o’clock          | 1367 |1·462| ·974| ·731| ·585|·487 |·418 |
  |     ditto and Sundays| 1586 |1·26 | ·84 | ·63 | ·504|·42  |·36  |
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1636 |1·222| ·814| ·611| ·489|·407 |·349 |
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 1855 |1·078| ·718| ·539| ·431|·359 |·308 |
  |  11 o’clock          | 1680 |1·19 | ·794| ·595| ·476|·397 |·34  |
  |     ditto and Sundays| 1951 |1·024| ·682| ·512| ·409|·341 |·293 |
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1949 |1·026| ·684| ·513| ·41 |·342 |·294 |
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 2220 | ·9  | ·6  | ·45 | ·36 |·3   |·257 |
  |  12 o’clock          | 1993 |1·   | ·668| ·502| ·4  |·334 |·287 |
  |     ditto and Sundays| 2316 | ·862| ·574| ·432| ·345|·287 |·247 |
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 2262 | ·884| ·59 | ·442| ·353|·295 |·255 |
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 2585 | ·772| ·514| ·387| ·309|·257 |·221 |
  |   1 o’clock          | 2306 | ·866| ·578| ·434| ·347|·289 |·247 |
  |     ditto and Sundays| 2681 | ·746| ·498| ·373| ·298|·249 |·213 |
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 2575 | ·776| ·518| ·388| ·31 |·259 |·222 |
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 2950 | ·678| ·452| ·339| ·271|·226 |·193 |
  |   All night          | 4327 | ·462| ·308| ·231| ·185|·154 |·132 |
  +----------------------+------+-----+-----+-----+-----+-----+-----+

  +----------------------+------+----------------+-----------------+
  |                      |      |    3 Jets.     |  Small Argand.  |
  |                      |      |                |                 |
  |                      | No.  +----+-----+-----+-----+-----+-----+
  |   Time of Burning    | of   |Cub.|Cub. |Cub. |Cub. |Cub. |Cub. |
  |      per annum.      |Hours.| ft.| ft. | ft. | ft. | ft. | ft. |
  |                      |[30]  | 2  |2-1/2|  3  |3-1/2|  4  |4-1/2|
  +----------------------+------+----+-----+-----+-----+-----+-----+
  |From Dusk to 8 o’clock|  781 |·64 |·5132|·4268|·3658|·3201|·2846|
  |     ditto and Sundays|  902 |·554|·4434|·3695|·3168|·2771|·2464|
  |     ditto and from 6 |      |    |     |     |     |     |     |
  |     o’clock mornings | 1050 |·476|·381 |·3174|·272 |·2381|·2116|
  |     ditto and Sundays|      |    |     |     |     |     |     |
  |     and from ditto   | 1172 |·426|·3412|·2844|·2438|·2133|·1896|
  |   9 o’clock          | 1054 |·474|·3794|·3162|·271 |·2371|·2108|
  |     ditto and Sundays| 1221 |·409|·3376|·273 |·234 |·2047|·182 |
  |     ditto and from 6 |      |    |     |     |     |     |     |
  |     o’clock mornings | 1323 |·378|·3022|·2519|·2158|·1889|·1678|
  |     ditto and Sundays|      |    |     |     |     |     |     |
  |     and from ditto   | 1490 |·335|·2684|·2236|·1918|·1675|·1492|
  |  10 o’clock          | 1367 |·366|·2926|·2438|·209 |·1829|·1626|
  |     ditto and Sundays| 1586 |·315|·2522|·2101|·1802|·1576|·14  |
  |     ditto and from 6 |      |    |     |     |     |     |     |
  |     o’clock mornings | 1636 |·305|·2444|·2037|·1746|·1528|·1358|
  |     ditto and Sundays|      |    |     |     |     |     |     |
  |     and from ditto   | 1855 |·269|·2156|·1796|·154 |·1347|·1198|
  |  11 o’clock          | 1680 |·297|·238 |·1984|·17  |·1488|·133 |
  |     ditto and Sundays| 1951 |·256|·2048|·1707|·1466|·1281|·1138|
  |     ditto and from 6 |      |    |     |     |     |     |     |
  |     o’clock mornings | 1949 |·256|·2052|·171 |·1466|·1282|·114 |
  |     ditto and Sundays|      |    |     |     |     |     |     |
  |     and from ditto   | 2220 |·225|·1802|·1501|·1286|·1126|·1   |
  |  12 o’clock          | 1993 |·251|·2006|·1672|·1434|·1254|·1114|
  |     ditto and Sundays| 2316 |·215|·1726|·1439|·1236|·1079|·0958|
  |     ditto and from 6 |      |    |     |     |     |     |     |
  |     o’clock mornings | 2262 |·221|·1768|·1476|·1274|·1105|·0982|
  |     ditto and Sundays|      |    |     |     |     |     |     |
  |     and from ditto   | 2585 |·193|·1546|·1289|·1104|·0967|·0858|
  |   1 o’clock          | 2306 |·217|·1734|·1445|·1238|·1080|·0962|
  |     ditto and Sundays| 2681 |·186|·1492|·1243|·1066|·0932|·0828|
  |     ditto and from 6 |      |    |     |     |     |     |     |
  |     o’clock mornings | 2575 |·194|·1552|·1294|·111 |·0971|·0862|
  |     ditto and Sundays|      |    |     |     |     |     |     |
  |     and from ditto   | 2950 |·169|·1356|·113 |·0968|·0847|·0754|
  |   All night          | 4327 |·115|·6924|·077 |·066 |·0578|·0515|
  +----------------------+------+----+-----+-----+-----+-----+-----+

  +----------------------+------+-----------------+-----------------+
  |                      |      |  Large Argand.  |Fancy and extra- |
  |                      |      |                 |vagant Burners.  |
  |                      | No.  +-----+-----+-----+-----+-----+-----+
  |   Time of Burning    | of   |Cub. |Cub. |Cub. |Cub. |Cub. |Cub. |
  |      per annum.      |Hours.| ft. | ft. | ft. | ft. | ft. | ft. |
  |                      |[30]  |  5  |  6  |  7  |  8  |  9  | 10  |
  +----------------------+------+-----+-----+-----+-----+-----+-----+
  |From Dusk to 8 o’clock|  781 |·2561|·2134|·1829|·16  |·1423|·128 |
  |     ditto and Sundays|  902 |·2217|·1848|·1584|·1383|·1232|·1108|
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1050 |·1905|·1587|·136 |·119 |·1058|·0952|
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 1172 |·1706|·1422|·1219|·1067|·0948|·0853|
  |   9 o’clock          | 1054 |·1897|·1581|·1355|·1185|·1054|·0948|
  |     ditto and Sundays| 1221 |·1638|·1365|·117 |·1024|·091 |·0819|
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1323 |·1511|·1259|·1079|·0945|·0839|·0755|
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 1490 |·1312|·1118|·0959|·0839|·0746|·0671|
  |  10 o’clock          | 1367 |·1463|·1219|·1045|·0914|·0813|·0731|
  |     ditto and Sundays| 1586 |·1261|·1051|·0901|·0789|·07  |·0630|
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1636 |·1222|·1019|·0873|·0764|·0679|·0611|
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 1855 |·1078|·0898|·077 |·0674|·0599|·0539|
  |  11 o’clock          | 1680 |·119 |·0992|·085 |·0744|·0665|·0595|
  |     ditto and Sundays| 1951 |·1024|·0854|·0733|·064 |·0569|·0512|
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 1949 |·1026|·0855|·0733|·0641|·057 |·0513|
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 2220 |·0981|·0751|·0643|·0563|·05  |·045 |
  |  12 o’clock          | 1993 |·1003|·0836|·0717|·0627|·0557|·0502|
  |     ditto and Sundays| 2316 |·0863|·0719|·0618|·0539|·0479|·0432|
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 2262 |·0884|·0737|·0637|·0552|·0491|·0442|
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 2585 |·0773|·0645|·0552|·0483|·0429|·0387|
  |   1 o’clock          | 2306 |·0867|·0723|·0619|·0542|·0481|·0434|
  |     ditto and Sundays| 2681 |·0746|·0621|·0533|·0466|·0414|·0373|
  |     ditto and from 6 |      |     |     |     |     |     |     |
  |     o’clock mornings | 2575 |·0776|·0647|·0555|·0485|·0431|·0388|
  |     ditto and Sundays|      |     |     |     |     |     |     |
  |     and from ditto   | 2950 |·0678|·0565|·0484|·0424|·0377|·0339|
  |   All night          | 4327 |·0462|·0385|·033 |·0289|·0257|·0231|
  +----------------------+------+-----+-----+-----+-----+-----+-----+

  _To use the Table._--Select the hour to which it is agreed the gas is
  to burn,--9, 10, 11 o’clock, Sundays, &c., as the case may be, and the
  description of the burner.--Multiply the decimal number opposite to it
  by the amount in shillings agreed to be paid per annum, and the
  product will be the sum received per m. cubic feet for the gas.

  _Example._--Suppose a small argand which should burn 3-1/2 feet per
  hour, is agreed for till 9 o’clock at 2_l._ per annum. Look along the
  line of 9 o’clock till you arrive at the column of 3-1/2 feet per
  hour, and you find the number, ·271. Multiply this number by 40_s._
  and the result gives 10_s._ 10_d._ per m. cubic feet. But suppose
  instead of keeping to 9 o’clock the party burns till 1 o’clock,
  Sundays and mornings, and by enlarging the holes or height of flame
  consumes 8 cubic feet of gas per hour; then you have the number,
  ·0424, which multiplied by 40_s._, still the price paid, gives 1_s._
  8_d._ per m. cubic feet only, and so on for any greater or lesser
  variation of the agreement.


  [30] The “number of hours” includes 1/4 of an hour allowed for
  shutting shops, and 1 hour’s extra burning on Saturday nights.

GENERAL SUMMARY.

For lighting London and its suburbs with gas, there are--

18 public gas works.

12    do.     companies.

2,800,000_l._ capital employed in works, pipes, tanks, gas-holders,
apparatus.

450,000_l._ yearly revenue derived.

180,000 tons of coals used in the year for making gas.

1,460,000,000 cubic feet of gas made in the year.

134,300 private burners supplied to about 40,000 consumers.

30,400 public or street do. N. B. about 2650 of these are in the _city_
of London.

380 lamplighters employed.

176 gas-holders; several of them double ones, capable of storing
5,500,000 cubic feet.

890 tons of coals used in the retorts on the shortest day, in 24 hours.

7,120,000 cubic feet of gas used in longest night, say 24th December.

About 2500 persons are employed in the metropolis alone, in this branch
of manufacture.

Between 1822 and 1827 the quantity nearly doubled itself, and that in 5
years.

Between 1827 and 1837 it doubled itself again.

Mr. Kirkham, engineer, obtained a patent, in June, 1837, for an improved
mode of removing the carbonaceous incrustation from the internal
surfaces of gas retorts. He employs a jet or jets of heated atmospheric
air, or other gases containing oxygen, which he impels with force into
the interior of such retorts as have become incrusted in consequence of
the decomposition of the coal. The retort is to be kept thoroughly red
hot during the application of the proposed jets. An iron pipe,
constructed with several flexible joints, leading from a blowing
machine, is bent in such a way as to allow its nozzle end to be
introduced within the retort, and directed to any point of its surface.

I should suppose that air, even at common temperatures, applied to a
retort ignited to the pitch of making gas, would burn away the
incrustations; but hot air will, no doubt, be more powerful.


GAS-HOLDER; a vessel for containing and preserving gas, of which various
forms are described by chemical writers.


GASOMETER, means properly a measurer of gas, though it is employed often
to denote a recipient of gas of any kind. See the article GAS-LIGHT.


GAUZE WIRE CLOTH; is a textile fabric, either plane or tweelled, made of
brass, iron, or copper wire, of very various degrees of fineness and
openness of texture. Its chief uses are for sieves, and safety lamps.


GAY-LUSSITE, is a white mineral of a vitreous fracture, which
crystallizes in oblique rhomboidal prisms; specific gravity from 1·93 to
1·95; scratches gypsum, but is scratched by calcspar; affords water by
calcination; it consists of carbonic acid 28·66; soda, 20·44; lime,
17·70; water, 32·20; clay, 1·00. It is in fact, by my analysis, a
hydrated soda-carbonate of lime in atomic proportions. This mineral
occurs abundantly in insulated crystals, disseminated through the bed of
clay which covers the _urao_, or native sesquicarbonate of soda, at
Lagunilla in Colombia.


GELATINE; (Eng. and Fr.; _Gallert_, _Leim_, Germ.) is an animal product
which is never found in the humours, but it may be obtained by boiling
with water the soft and solid parts; as the muscles, the skin, the
cartilages, bones, ligaments, tendons, and membranes. Isinglass consists
almost entirely of gelatine. This substance is very soluble in boiling
water; the solution forms a tremulous mass of jelly when it cools. Cold
water has little action upon gelatine. Alcohol and tannin (tannic acid,
see GALL-NUTS) precipitate gelatine from its solution; the former by
abstracting the water, the latter by combining with the substance itself
into an insoluble compound; of the nature of leather. No other acid,
except the tannic, and no alkali possesses the property of precipitating
gelatine. But chlorine and certain salts render its solution more or
less turbid; as the nitrate and bi-chloride of mercury, the
proto-chloride of tin, and a few others. Sulphuric acid converts a
solution of gelatine at a boiling heat into sugar. See LIGNEOUS FIBRE.
Gelatine consists of carbon, 47·88; hydrogen, 7·91; oxygen, 27·21. See
GLUE and ISINGLASS.


GEMS, are precious stones, which, by their colour, limpidity, lustre,
brilliant polish, purity, and rarity, are sought after as objects of
dress and decoration. They form the principal part of the crown jewels
of kings, not only from their beauty, but because they are supposed to
comprize the greatest value in the smallest bulk; for a diamond, no
larger than a nut or an acorn, may be the representative sign of the
territorial value of a whole country, the equivalent in commercial
exchange of a hundred fortunes, acquired by severe toils and privations.

Among these beautiful minerals mankind have agreed in forming a select
class, to which the title of _gems_ or _jewels_ has been appropriated;
while the term _precious stone_ is more particularly given to substances
which often occur under a more considerable volume than _fine stones_
ever do.

Diamonds, sapphires, emeralds, rubies, topazes, hyacinths, and
chrysoberyls, are reckoned the most valuable _gems_.

Crystalline quartz, pellucid opalescent or of various hues, amethyst,
lapis lazuli, malachite, jasper, agate, &c., are ranked in the much more
numerous and inferior class of ornamental stones. These distinctions are
not founded upon any strict philosophical principle, but are regulated
by a conventional agreement, not very well defined; for it is impossible
to subject these creatures of fashion and taste to the rigid
subdivisions of science. We have only to consider the value currently
attached to them, and take care not to confound two stones of the same
colour, but which may be very differently prized by the _virtuoso_.

Since it usually happens that the true gems are in a cut and polished
state, or even set in gold or silver, we are thereby unable to apply to
them the criteria of mineralogical and chemical science. The cutting of
the stone has removed or masked its crystalline character, and
circumstances rarely permit the phenomena of double or single refraction
to be observed; while the test by the blowpipe is inadmissible. Hence
the only scientific resources that remain are the trial by electricity,
which is often inconclusive; the degree of hardness, a criterion
requiring great experience in the person who employs it; and, lastly,
the proof by specific gravity, unquestionably one of the surest means of
distinguishing the really fine gems from ornamental stones of similar
colour. This proof can be applied only to a stone that is not set; but
the richer gems are usually dismounted, when offered for sale.

This character of specific gravity may be applied by any person of
common intelligence, with the aid of a small hydrostatic balance. If,
for example, a stone of a fine crimson-red colour, be offered for sale,
as an oriental ruby; the purchaser must ascertain if it be not a
Siberian tourmaline, or ruby spinel. Supposing its weight in air to be
100 grains, if he finds it reduced to 69 grains, when weighed in water,
he concludes that its bulk is equal to that of 31 grains of water, which
is its loss of weight. Now, a real sapphire which weighs 100 grains in
air, would have weighed 76·6 in water; a spinel ruby of 100 grains would
have weighed 72·2 in water, and a Siberian tourmaline of 100 grains
would have weighed only 69 grains in water. The quality of the stone in
question is, therefore, determined beyond all dispute, and the purchaser
may be thus protected from fraud.

The _sard_ of the English jewellers (_Sardoine_, French) is a stone of
the nature of agate, having an orange colour more or less deep, and
passing by insensible shades into yellow, reddish, and brown; whence it
has been agreed to unite under this denomination all the agates whose
colour verges upon brown. It should be remarked, however, that the sard
presents, in its interior and in the middle of its ground, concentric
zones, or small nebulosities, which are not to be seen in the red
cornelian, properly so called. The ancients certainly knew our sard,
since they have left us a great many of them engraved, but they seem to
have associated under the title _sarda_ both the sardoine of the French,
and our cornelians and calcedonies. Pliny says that the _sarda_ came
from the neighbourhood of a city of that name in Lydia, and from the
environs of Babylon. Among the engraved sards which exist in the
collection of antiques in the Bibliothèque Royale of Paris, there is an
Apollo remarkable for its fine colour and great size. When the stone
forms a part of the agate-onyx, it is called sardonyx. For further
details upon Gems, and the art of cutting and engraving them, see
LAPIDARY.


GEOGNOSY, means a knowledge of the structure of the earth; GEOLOGY, a
description of the same. The discussion of this subject does not come
within the province of this Dictionary.


GERMAN SILVER. See the latter end of the article COPPER.


GERMINATION; (Eng. and Fr.; _Das Keimen_, Germ.) is the first sprouting
of a seed after it is sown, or when, after steeping, it is spread upon
the malt floor. See BEER.


GIG MACHINES, are rotatory drums, mounted with thistles or wire teeth
for teazling cloth. See WOOLLEN MANUFACTURE.


GILDING (_Dorure_, Fr.; _Vergoldung_, Germ.); is the art of coating
surfaces with a thin film of gold. For a full discussion of this
subject, see GOLD. Mr. Elkington, gilt toy maker, obtained a patent, in
June, 1836, for gilding copper, brass, &c., by means of potash or soda
combined with carbonic acid, and with a solution of gold. Dissolve, says
he, 5 oz. troy of fine gold in 52 oz. avoirdupois of nitro-muriatic acid
of the following proportions: viz. 21 oz. of pure nitric acid, of spec.
grav. 1·45, 17 oz. of pure muriatic acid, of spec. grav. 1·15; with 14
oz. of distilled water.

The gold being put into the mixture of acids and water, they are to be
heated in a glass or other convenient vessel till the gold is dissolved;
and it is usual to continue the application of heat after this is
effected, until a reddish or yellowish vapour ceases to rise.

The clear liquid is to be carefully poured off from any sediment which
generally appears and results from a small portion of silver, which is
generally found in alloy with gold. The clear liquid is to be placed in
a suitable vessel of stone, pottery ware is preferred. Add to the
solution of gold 4 gallons of distilled water, and 20 pounds of
bicarbonate of potash of the best quality; let the whole boil moderately
for 2 hours, the mixture will then be ready for use.

The articles to be gilded having been first perfectly cleaned from scale
or grease, they are to be suspended on wires, conveniently for a workman
to dip them in the liquid, which is kept boiling. The time required for
gilding any particular article will depend on circumstances, partly on
the quantity of gold remaining in the liquid, and partly on the size and
weight of the article; but a little practice will readily give
sufficient guidance to the workman.

Supposing the articles desired to be gilded be brass or copper buttons,
or small articles for gilt toys, or ornaments of dress, such as earrings
or bracelets, a considerable number of which may be strung on a hoop, or
bended piece of copper or brass wire, and dipped into the vessel
containing the boiling liquid above described, and moved therein, the
requisite gilding will be generally obtained in from a few seconds to a
minute; this is when the liquid is in the condition above described, and
depending on the quality of the gilding desired; but if the liquid has
been used some time, the quantity of gold will be lessened, which will
vary the time of operating to produce a given effect, or the colour
required, all which will quickly be observed by the workman; and by
noting the appearance of the articles from time to time, he will know
when the desired object is obtained, though it is desirable to avoid as
much as possible taking the articles out of the liquid.

When the operation is completed, the workman perfectly washes the
articles so gilded with clean water; they may then be submitted to the
usual process of colouring.

If the articles be cast figures of animals, or otherwise of considerable
weight, compared with the articles above mentioned, the time required to
perform the process will be greater.

In case it is desired to produce what is called a dead appearance, it
may be performed by several processes: the one usually employed is to
dead the articles in the process of cleaning, as practised by
brass-founders and other trades; it is produced by an acid, prepared for
that purpose, sold by the makers under the term “deading aquafortis,”
which is well understood.

It may also be produced by a weak solution of nitrate of mercury,
applied to the articles previous to the gilding process, as is practised
in the process of gilding with mercury, previous to spreading the
amalgam, but generally a much weaker solution; or the articles having
been gilded may be dipped in a solution of nitrate of mercury, and
submitted to heat to expel the same, as is practised in the usual
process of gilding.

It is desirable to remark, that much of the beauty of the result depends
on the well cleaning of the articles, and it is better to clean them by
the ordinary processes, and at once pass them into the liquid to be
gilded. See GOLD, towards the end.


GIN, or _Geneva_, from _Genievre_ (juniper), is a kind of ardent spirits
manufactured in Holland, and hence called Hollands gin in this country,
to distinguish it from British gin. The materials employed in the
distilleries of Schiedam, are two parts of unmalted rye from Riga,
weighing about 54 lbs. per bushel, and one part of malted bigg, weighing
about 37 lbs. per bushel. The mash tun, which serves also as the
fermenting tun, has a capacity of nearly 700 gallons, being about five
feet in diameter at the mouth, rather narrower at the bottom, and 4-1/2
feet deep; the stirring apparatus is an oblong rectangular iron grid,
made fast to the end of a wooden pole. About a barrel, = 36 gallons of
water, at a temperature of from 162° to 168° (the former heat being best
for the most highly dried rye), are put into the mash tun for every
1-1/2 cwt. of meal, after which the malt is introduced and stirred, and
lastly the rye is added. Powerful agitation is given to the magma till
it becomes quite uniform; a process which a vigorous workman piques
himself upon executing in the course of a few minutes. The mouth of the
tun is immediately covered over with canvas, and further secured by a
close wooden lid, to confine the heat; it is left in this state for two
hours. The contents being then stirred up once more, the _transparent_
spent wash of a preceding mashing is first added, and next as much cold
water as will reduce the temperature of the whole to about 85° F. The
best Flanders yeast, which had been brought, for the sake of carriage,
to a doughy consistence by pressure, is now introduced to the amount of
one pound for every 100 gallons of the mashed materials.

The gravity of the fresh wort is usually from 33 to 38 lbs. per Dicas’
hydrometer; and the fermentation is carried on from 48 to 60 hours, at
the end of which time the attenuation is from 7 to 4 lbs., that is, the
specific gravity of the supernatant wash is from 1·007 to 1·004.

The distillers are induced by the scarcity of beer-barm in Holland, to
skim off a quantity of the yeast from the fermenting tuns, and to sell
it to the bakers, whereby they obstruct materially the production of
spirit, though they probably improve its quality, by preventing its
impregnation with yeasty particles; an unpleasant result which seldom
fails to take place in the whiskey distilleries of the United Kingdom.

On the third day after the fermenting tun is set, the wash containing
the grains is transferred to the still, and converted into low wines. To
every 100 gallons of this liquor, two pounds of juniper berries, from 3
to 5 years old, being added along with about one quarter of a pound of
salt, the whole are put into the low wine still, and the fine Hollands
spirit is drawn off by a gentle and well-regulated heat, till the magma
becomes exhausted; the first and the last products being mixed together;
whereby a spirit, 2 to 3 per cent. above our hydrometer proof, is
obtained, possessing the peculiar fine aroma of gin. The quantity of
spirit varies from 18 to 21 gallons per quarter of grain; this large
product being partly due to the employment of the spent wash of the
preceding fermentation; an addition which contributes at the same time
to improve the flavour.

For the above instructive details of the manufacture of genuine
Hollands, I am indebted to Robert More, Esq., formerly of Underwood,
distiller, who after studying the art at Schiedam, tried to introduce
that spirit into general consumption in this country, but found the
palates of our gin-drinkers too much corrupted to relish so pure a
beverage.


GINNING, is the name of the operation by which the filaments of cotton
are separated from the seeds. See COTTON MANUFACTURE.


GLANCE COAL, or anthracite, of which there are two varieties, the
_slaty_ and the _conchoidal_. See ANTHRACITE.


GLASS (_Verre_, Fr.; _Glas_, Germ.); is a transparent solid formed by
the fusion of siliceous and alkaline matter. It was known to the
Phenicians, and constituted for a long time an exclusive manufacture of
that people, in consequence of its ingredients, natron, sand, and fuel,
abounding upon their coasts. It is probable that the more ancient
Egyptians were unacquainted with glass, for we find no mention of it in
the writings of Moses. But according to Pliny and Strabo, the glass
works of Sidon and Alexandria were famous in their times, and produced
beautiful articles; which were cut, engraved, gilt, and stained of the
most brilliant colours, in imitation of precious stones. The Romans
employed glass for various purposes; and have left specimens in
Herculaneum of window-glass, which must have been blown by methods
analogous to the modern. The Phenician processes seem to have been
learned by the Crusaders, and transferred to Venice in the 13th century,
where they were long held secret, and formed a lucrative commercial
monopoly. Soon after the middle of the 17th century, Colbert enriched
France with the blown mirror glass manufacture.

Chance undoubtedly had a principal share in the invention of this
curious fabrication, but there were circumstances in the most ancient
arts likely to lead to it; such as the fusing and vitrifying heats
required for the formation of pottery, and for the extraction of metals
from their ores. Pliny ascribes the origin of glass to the following
accident. A merchant-ship laden with natron being driven upon the coast
at the mouth of the river Belus, in tempestuous weather, the crew were
compelled to cook their victuals ashore, and having placed lumps of the
natron upon the sand, as supports to the kettles, found to their
surprise masses of transparent stone among the cinders. The sand of this
small stream of Galilee, which runs from the foot of Mount Carmel, was
in consequence supposed to possess a peculiar virtue for making glass,
and continued for ages to be sought after and exported to distant
countries for this purpose.

Agricola, the oldest author who has written technically upon glass,
describes furnaces and processes closely resembling those employed at
the present day. Neri, Kunckel, Henckel, Pott, Achard, and some other
chemists, have since then composed treatises upon the subject; but Neri,
Bosc, Antic, Loysel, and Allut, in the Encyclopédie Méthodique, are the
best of the elder authorities.

The window-glass manufacture was first begun in England in 1557, in
Crutched Friars, London; and fine articles of flint-glass were soon
afterwards made in the Savoy House, Strand. In 1635 the art received a
great improvement from Sir Robert Mansell, by the use of coal fuel
instead of wood. The first sheets of blown glass for looking glasses and
coach windows were made in 1673 at Lambeth, by Venetian artisans
employed under the patronage of the Duke of Buckingham.

The casting of mirror-plates was commenced in France about the year
1688, by Abraham Thevart; an invention which gave rise soon afterwards
to the establishment of the celebrated works of St. Gobin, which
continued for nearly a century the sole place where this highly prized
object of luxury was well made. In excellence and cheapness, the French
mirror-plate has been, however, for some time rivalled by the English.

The analysis of modern chemists, which will be detailed in the course of
this article, and the light thrown upon the manufacture of glass in
general by the accurate means now possessed of purifying its several
ingredients, would have brought the art to the highest state of
perfection in this country, but for the vexatious interference and
obstructions of our excise laws.

The researches of Berzelius having removed all doubts concerning the
acid character of silica, the general composition of glass presents now
no difficulty of conception. This substance consists of one or more
salts; which are silicates with bases of potash, soda, lime, oxide of
iron, alumina, or oxide of lead; in any of which compounds we can
substitute one of these bases for another, provided that one alkaline
base be left. Silica in its turn may be replaced by the boracic acid,
without causing the glass to lose its principal characters.

Under the title glass are therefore comprehended various substances
fusible at a high temperature, solid at ordinary temperatures,
brilliant, generally more or less transparent, and always brittle. The
following chemical distribution of glasses has been proposed.

1. Soluble glass; a simple silicate of potash or soda; or of both these
alkalis.

2. Bohemian or crown glass; silicate of potash and lime.

3. Common window and mirror glass; silicate of soda and lime; sometimes
also of potash.

4. Bottle glass; silicate of soda, lime, alumina and iron.

5. Ordinary crystal glass; silicate of potash and lead.

6. Flint glass; silicate of potash and lead; richer in lead than the
preceding.

7. Strass; silicate of potash and lead; still richer in lead.

8. Enamel; silicate and stannate or antimoniate of potash or soda, and
lead.

The glasses which contain several bases are liable to suffer different
changes when they are melted or cooled slowly. The silica is divided
among these bases, forming new compounds in definite proportions, which
by crystallizing, separate from each other, so that the general mixture
of the ingredients which constituted glass is destroyed. It becomes then
very hard, fibrous, opaque, much less fusible, a better conductor of
electricity and of heat; forming what Reaumur styled _devitrified_
glass; and what is called after him, Reaumur’s porcelain.

This altered glass can always be produced in a more or less perfect
state, by melting the glass and allowing it to cool very slowly; or
merely by heating it to the softening pitch, and keeping it at this heat
for some time. The process succeeds best with the most complex vitreous
compounds, such as bottle glass; next with ordinary window glass; and
lastly with glass of potash and lead.

This property ought to be kept constantly in view in manufacturing
glass. It shows why in making bottles we should fashion them as quickly
as possible with the aid of a mould, and reheat them as seldom as may be
absolutely necessary. If it be often heated and cooled, the glass loses
its ductility, becomes refractory, and exhibits a multitude of stony
granulations throughout its substance. When coarse glass is worked at
the enameller’s lamp, it is apt to change its nature in the same way, if
the workman be not quick and expert at his business.

From these facts we perceive the importance of making a careful choice
of the glass intended to be worked in considerable masses, such as the
large object glasses of telescopes; as their annealing requires a very
slow process of refrigeration, which is apt to cause devitrified specks
and clouds. For such purposes, therefore, no other species of glass is
well adapted except that with basis of potash and lead; or that with
basis of potash and lime. These two form the best flint glass, and crown
glass; and they should be exclusively employed for the construction of
the object glasses of achromatic telescopes.


GLASS-MAKING, _general principles of_. Glass may be defined in technical
phraseology, to be a transparent homogeneous compound formed by the
fusion of silica with oxides of the alkaline, earthy, or common metals.
It is usually colourless, and then resembles rock crystal, but is
occasionally stained by accident or design with coloured metallic
oxides. At common temperatures it is hard and brittle, in thick pieces;
in thin plates or threads, flexible and elastic; sonorous when struck;
fracture conchoidal, and of that peculiar lustre called vitreous; at a
red heat, becoming soft, ductile and plastic. Besides glass properly so
called, other bodies are capable of entering into vitreous fusion, as
phosphoric acid, boracic acid, arsenic acid, as also certain metallic
oxides, as of lead, and antimony, and several chlorides; some of which
are denominated glasses. Impure and opaque vitriform masses are called
slags; such are the productions of blast iron furnaces and many
metallurgic operations.

Silica, formerly styled the earth of flints, which constitutes the basis
of all commercial glass, is infusible by itself in the strongest fire of
our furnaces; but its vitreous fusion is easily effected by a competent
addition of potash or soda, either alone or mixed with lime or litharge.
The silica, which may be regarded as belonging to the class of acids,
combines at the heat of fusion with these bases, into saline compounds;
and hence glass may be viewed as a silicate of certain oxides, in which
the acid and the bases exist in equivalent proportions. Were these
proportions, or the quantities of the bases which silica requires for
its saturation at the melting point, exactly ascertained, we might
readily determine beforehand the best proportions of materials for the
glass manufacture. But as this is far from being the case, and as it is,
moreover, not improbable that the capacity of saturation of the silica
varies with the temperature, and that the properties of glass also vary
with the bases, we must, in the present state of our knowledge, regulate
the proportions rather by practice than by theory, though the latter may
throw an indirect light upon the subject. For example, a good
colourless glass has been found by analysis to consist of 72 parts of
silica, 13 parts of potash, and 10 parts of lime, in 95 parts. If we
reduce these numbers to the equivalent ratios, we shall have the
following results; taking the atomic weights as given by Berzelius.

  1 atom potash =  590  14·67
  1      lime      356   8·84
  3      silica   1722  42·79 } 71·49
  2      silica   1155  28·70 }
                  ----  -----
                  3823  95·00

This glass would therefore have been probably better compounded with the
just atomic proportions, to which it nearly approaches, viz. 71·49
silica, 14·67 potash, and 8·84 lime, instead of those given above as its
actual constituents.

The proportions in which silica unites with the alkaline and other
oxides are modified by the temperature as above stated; the lower the
heat, the less silica will enter into the glass, and the more of the
base will in general be required. If a glass which contains an excess of
alkali be exposed to a much higher temperature than that of its
formation, a portion of the base will be set free to act upon the
materials of the earthen pot, or to be dissipated in fumes, until such a
silicate remains as to constitute a permanent glass corresponding to
that temperature. Hence the same mixture of vitrifiable materials will
yield very different results, according to the heats in which it is
fused and worked in the glass-house; and therefore the composition
should always be referrible to the going of the furnace. When a species
of glass which at a high temperature formed a transparent combination
with a considerable quantity of lime, is kept for some time in fusion at
a lower temperature, a portion of the lime unites with the silica into
another combination of a semi-vitreous or even of a stony aspect, so as
to spoil the transparency of the glass altogether. There is probably a
supersilicate, and a subsilicate formed in such cases; the latter being
much the more fusible of the two compounds. The Reaumur’s porcelain
produced by exposing bottle glass to a red heat for 24 hours, is an
example of this species of vitreous change in which new affinities are
exercised at a lower temperature. An excess of silica, caused by the
volatilization of alkaline matter with too strong firing, will bring on
similar appearances.

The specific gravity of glass varies from 2·3 to 3·6. That of least
specific gravity consists of merely silica and potash fused together;
that with lime is somewhat denser, and with oxide of lead denser still.
Plate glass made from silica, soda, and lime, has a specific gravity
which varies from 2·50 to 2·6; crystal or flint glass from 3·0 to 3·6.

The power of glass to resist the action of water, alkalis, acids, air,
and light, is in general the greater, the higher the temperature
employed in its manufacture, the smaller the proportion of its fluxes,
and the more exact the equivalent ratios of its constituents. When glass
contains too much alkali, it is partially soluble in water. Most crystal
glass is affected by having water boiled in it for a considerable time;
but crown glass being poorer in alkali, and containing no lead, resists
that action much longer, and is therefore better adapted to chemical
operations. The affinity of glass for water, or its hygrometric
attraction, is also proportional to the quantity of alkali which it
contains. In general also potash glass is more apt to become damp than
soda glass, agreeably to the respective hygrometric properties of these
two alkalis, and also to the smaller proportion of soda than of potash
requisite to form glass.

Air and light operate upon glass probably by their oxidizing property.
Bluish or greenish coloured glasses become by exposure colourless, in
consequence undoubtedly of the peroxidizement of the iron, to whose
protoxide they owe their tint; other glasses become purple red from the
peroxidizement of the manganese. The glasses which contain lead, suffer
another kind of change in the air, if sulphuretted hydrogen be present;
the oxide of lead is converted into a sulphuret, with the effect of
rendering the surface of the glass opaque and iridescent. The more lead
is in the glass, the quicker does this iridescence supervene. By boiling
concentrated sulphuric acid in a glass vessel, or upon glass, we can
ascertain its power of resisting ordinary menstrua. Good glass will
remain smooth and transparent; bad glass will become rough and dim.

The brittleness of unannealed glass by change of temperature is
sometimes very great. I have known a thick vessel to fly by vicissitudes
of the atmosphere alone. This defect may be corrected by slowly heating
the vessel in salt-water or oil to the highest pitch consistent with the
nature of these liquids, and letting it cool very slowly. Within the
limits of that range of heat, it will, in consequence of this treatment,
bear alternations of temperature without cracking as before.

It has been said that glass made from silica and alkalis alone, will not
resist the action of water, but that the addition of a little lime is
necessary for this effect. In general 100 parts of quartzose sand
require 33 parts of dry carbonate of soda for their vitrification, and
45 parts of dry carbonate of potash. But to make unchangeable alkaline
glass, especially with potash, a smaller quantity of this than the above
should be used, with a very violent heat. A small proportion of lime
increases the density, hardness, and lustre of glass; and it aids in
decomposing the alkaline sulphates and muriates always present in the
pearl ash of commerce. From 7 to 20 parts of dry slaked lime have been
added for 100 of silica, with advantage, it is said, in some German
glass manufactories, where the alkaline matter is soda; for potass does
not assimilate well with the calcareous earth.

In many glass works on the Continent, sulphate of soda is the form under
which alkaline matter is introduced into glass. This salt requires the
addition of 8 per cent. of charcoal to decompose and dissipate its acid;
a result which takes place at a high heat, without the addition of any
lime. 88 pounds of quartz-sand, 44 pounds of dry glauber salt, and 3
pounds of charcoal, properly mixed and fused, afford a limpid, fluent,
and workable glass; with the addition of 17 pounds of lime, these
materials fuse more readily into a plastic mass. If less carbon be
added, the fusion becomes more tedious. The two following formulæ afford
good glauber salt glass.

                               1.        2.
                             ------     ----
  Sand                       100        60·3
  Calcined sulphate of soda   50        26·8
  Lime                        20        10·8
  Charcoal                     2·65      2·1

The first mixture has been proved in the looking-glass manufactory of
Neuhaus near Vienna, and the second by the experiments of Kirn. The
fusion of the first requires 18, of the second 21 hours. The
bluish-green tinge which these otherwise beautiful and brilliant glasses
possess, is not removable by the ordinary means, such as manganese or
arsenic, which decolour alkaline glass. When the sulphate of soda and
charcoal are used in smaller proportions, the glass becomes more
colourless. The tinge is no doubt owing to the sulphur combining with
the oxide of sodium, in some such way as in the pigment _ultramarine_.

By a proper addition of galena (the native sulphuret of lead), to
glauber salt and quartz sand, without charcoal, it is said a tolerably
good crystal glass may be formed. The sulphuric acid of the salt is
probably converted by the reaction of the sulphuret of lead into
sulphurous acid gas, which is disengaged.

One atom of sulphuret of lead = 1495·67, is requisite to decompose 3
atoms of sulphate of soda = 2676. It is stated, on good authority, that
a good colourless glass may be obtained by using glauber salt without
charcoal, as by the following formula.

  Quartz-sand            100 pounds
  Calcined glauber salt   24
  Lime                    20
  Cullet of soda glass    12

The melting heat must be continued for 26-1/2 hours. A small quantity of
the sand is reserved to be thrown in towards the conclusion of the
process, in order to facilitate the expulsion of air bubbles. The above
mixture will bear to be blanched by the addition of manganese and
arsenic. The decomposition of the salt is in this case effected by the
lime, with which the sulphuric acid first combines, is then converted
into sulphurous acid, and dissipated. Glass made in this way was found
by analysis to consist of 79 parts of silica, 12 lime, and 9·6 soda,
without any trace of gypsum or sulphuric acid.

Glauber salt is partially volatilized by the heat of the furnace, and
acts upon the arch of the oven and the tops of the pots. This is best
prevented by introducing at first into the pots the whole of the salt
mixed with the charcoal, the lime, and one fourth part of the sand;
fusing this mixture at a moderate heat, and adding gradually afterwards
the remainder of the sand, increasing the temperature at the same time.
If we put in the whole ingredients together, as is done with potash
glass, the sand and lime soon fall to the bottom, while the salt rises
to the surface, and the combination becomes difficult and unequal.

Sulphate of potash acts in the same way as sulphate of soda.

Muriate of soda also, according to Kirn, may be used as a glass flux
with advantage. The most suitable proportions are 4 parts of potash, 2
of common salt, and 3 of lime, agreeably to the following
compositions:--

                                 1.     2.
                                ----   ----
  Quartz-sand                   60·0   75·1
  Calcined carbonate of potash  17·8   19·1
  Common salt                    8·9    9·5
  Lime                          13·3   14·3

For No. 1., the melting heat must be 10 hours, which turns out a very
pure, solid, good glass; for No. 2., 23 hours of the furnace are
required. Instead of the potash, glauber salt may be substituted; the
proportions being then 19·1 glauber salt, 9·5 muriate of soda, 14·3
lime, 75·1 sand, and 1·3 charcoal.

The oxide of lead is an essential constituent of the denser glasses, and
may be regarded as replacing the lime, so as to form with the
quartz-sand a silicate of lead. It assimilates best with purified pearl
ash, on account of the freedom of this alkali from iron, which is
present in most sodas.

Its atomic constitution may be represented as follows:--

  +----------------------------+-----------------+--------+-------+
  |                            |                 | Compu- |Analy- |
  |                            |                 |tation. | sis.  |
  |                            |                 +--------+-------+
  |Silicic acid                | 5 atoms = 2877· |  59·19 | 59·20 |
  |Oxide of lead               | 1       = 1394·5|  28·68 | 28·20 |
  |Potash                      | 1       =  590·0|  12·13 |  9·00 |
  |Oxides of iron and manganese|             --  |    --  |  1·40 |
  |                            |          -------+--------+-------+
  |                            |           4861·5| 100·00 |100·00 |
  +----------------------------+-----------------+--------+-------+

The above analysis by Berthier relates to a specimen of the best English
crystal glass, perfectly colourless and free from air-bubbles. This kind
of glass may however take several different proportions of potash and
silica to the oxide of lead.

The composition of mirror plate, as made on the Continent, is as
follows:--

  White quartz-sand             300 pounds
  Dry carbonate of soda         100
  Lime slaked in the air         43
  Cullet, or old glass          300

The manganese should not exceed one half per cent. of the weight of the
soda.

Optical glass requires to be made with very peculiar care. It is of two
different kinds; namely, _crown glass_ and _flint glass_. The latter
contains a considerable proportion of lead, in order to give it an
increased dispersive power upon the rays of light, in proportion to its
mean refractive power.

Optical crown glass should be perfectly limpid, and have so little
colour, that a pretty thick piece of it may give no appreciable tinge to
the rays of light. It should be exempt from striæ or veins as well as
air-bubbles, and have not the slightest degree of milkiness. It should
moreover preserve these qualities when worked in considerable
quantities. Potash is preferable to soda for making optical crown glass,
because the latter alkali is apt to make a glass which devitrifies and
becomes opalescent, by long exposure to heat in the annealing process. A
simple potash silicate would be free from this defect, but it would be
too attractive of moisture, and apt to decompose eventually by the
humidity of the atmosphere. It should therefore contain a small quantity
of lime, and as little potash as suffices for making a perfect glass at
a pretty high temperature. It is probably owing to the high heats used
in the English crown glass works, and the moderate quantity of alkali
(soda) which is employed, that our crown glass has been found to answer
so well for optical purposes.

PRACTICAL DETAILS OF THE MANUFACTURE OF GLASS.

The Venetians were the first in modern times who attained to any degree
of excellence in the art of working glass, but the French became
eventually so zealous of rivalling them, particularly in the
construction of mirrors, that a decree was issued by the court of
France, declaring not only that the manufacture of glass should not
derogate from the dignity of a nobleman, but that nobles alone should be
masters of glass-works. Within the last 30 or 40 years, Great Britain
has made rapid advances in this important art, and at the present day
her pre-eminence in every department hardly admits of dispute.

There are five different species of glass, each requiring a peculiar
mode of fabrication, and peculiar materials: 1. The coarsest and
simplest form of this manufacture is _bottle_ glass. 2. Next to it in
cheapness of material maybe ranked _broad_ or _spread window glass_. An
improved article of this kind is now made near Birmingham, under the
name of British or German plate. 3. Crown glass comes next, or window
glass, formed in large circular plates or discs. This glass is peculiar
to Great Britain. 4. Flint glass, crystal glass, or glass of lead. 5.
Plate or fine mirror glass.

The materials of every kind of glass are vitrified in pots made of a
pure refractory clay; the best kind of which is a species of shale or
slate clay dug out of the coal-formation near Stourbridge. It contains
hardly any lime or iron, and consists of silica and alumina in nearly
equal proportions. The masses are carefully picked, brushed, and ground
under edge iron wheels of considerable weight, and sifted through
sieves having 20 meshes in the square inch. This powder is moistened
with water (best hot), and kneaded by the feet or a loam-mill into an
uniform smooth paste. A large body of this dough should be made up at a
time, and laid by in a damp cellar to ripen. Previously to working it
into shapes, it should be mixed with about a fourth of its weight of
cement of old pots, ground to powder. This mixture is sufficiently
plastic, and being less contractile by heat, forms more solid and
durable vessels. Glass-house pots have the figure of a truncated cone,
with the narrow end undermost; those for bottle and window-glass, being
open at top, about 30 inches diameter at bottom, 40 inches at the mouth,
and 40 inches deep; but the flint-glass pots are covered in at top with
a dome-cap, having a mouth at the side, by which the materials are
introduced, and the glass is extracted. Bottle and crown-house pots are
from 3 to 4 inches thick; those for flint-houses are an inch thinner,
and of proportionally smaller capacity.

The well-mixed and kneaded dough is first worked upon a board into a
cake for the bottom; over this the sides are raised, by laying on its
edges rolls of clay above each other with much manual labour, and
careful condensation. The clay is made into lumps, is equalized, and
slapped much in the same way as for making POTTERY. The pots thus
fashioned must be dried very prudently, first in the atmospheric
temperature, and finally in a stove floor, which usually borrows its
heat directly from the glass-house. Before _setting the pots_ in the
furnace, they are annealed during 4 or 5 days, at a red heat in a small
reverberatory vault, made on purpose. When completely annealed, they are
transferred with the utmost expedition into their seat in the fire, by
means of powerful tongs supported on the axle of an iron-wheel carriage
frame, and terminating in a long lever for raising them and swinging
them round. The _pot-setting_ is a desperate service, and when
unskilfully conducted without due mechanical aids, is the forlorn hope
of the glass-founder.--_Quæque ipse miserrima vidi._ The celebrated
chemist, Dr. Irvine, caught his last illness by assisting imprudently at
this formidable operation. The working breast of the hot furnace must be
laid bare so as to open a breach for the extraction of the faulty pot,
and the insertion of the fresh one, both in a state of bright
incandescence. It is frightful to witness the eyes and fuming visages of
the workmen, with the blackening and smoking of their scorched woollen
clothes, exposed so long to the direct radiations of the flame. A light
mask and sack dress coated with tinfoil, would protect both their faces
and persons from any annoyance, at a very cheap rate.

The glass-houses are usually built in the form of a cone, from 60 to 100
feet high, and from 50 to 80 feet in diameter at the base. The furnace
is constructed in the centre of the area, above an arched or groined
gallery which extends across the whole space, and terminates without the
walls, in large folding doors. This cavern must be sufficiently high to
allow labourers to wheel out the cinders in their barrows. The middle of
the vaulted top is left open in the building, and is covered over with
the grate-bars of the furnace.

1. _Bottle glass._--The bottle-house and its furnace resemble nearly
_fig._ 505. The furnace is usually an oblong square chamber, built of
large fire-bricks, and arched over with fire-stone, a siliceous grit of
excellent quality extracted from the coal measures of Newcastle. This
furnace stands in the middle of the area; and has its base divided into
three compartments. The central space is occupied by the grate-bars; and
on either side is the platform or fire-brick _siege_, (seat,) raised
about 12 inches above the level of the ribs upon which the pots rest.
Each _siege_ is about 3 feet broad.

In the sides of the furnace, semi-circular holes of about a foot
diameter are left opposite to, and a little above the top of, each pot,
called working holes, by which the workmen shovel in the materials, and
take out the plastic glass. At each angle of the furnace there is
likewise a hole of about the same size, which communicates with the
calcining furnace of a cylindrical form, dome-shaped at top. The flame
that escapes from the founding or pot-furnace is thus economically
brought to reverberate on the raw materials of the bottle glass, so as
to dissipate their carbonaceous or volatile impurities, and convert them
into a frit. A bottle-house has generally eight other furnaces or
fire-arches; of which six are used for annealing the bottles after they
are blown, and two for annealing the pots, before setting them in the
furnace.

The laws of this country till lately prohibited the use for making
common bottles of any fine materials. Nothing but the common river sand,
and soap-boilers’ waste, was allowed. About 3 parts of waste, consisting
of the insoluble residuum of kelp, mixed with lime and a little saline
substance, were used for 1 part of sand. This waste was first of all
calcined in two of the fire arches or reverberatories reserved for that
purpose, called the coarse arches, where it was kept at a red heat, with
occasional stirring, from 24 to 30 hours, being the period of a journey
or _journée_, in which the materials could be melted and worked into
bottles. The roasted soap-waste was then withdrawn, under the name of
ashes, from its arch, coarsely ground, and mixed with its proper
proportion of sand. This mixture was now put into the fine arch, and
calcined during the working journey, which extended to 10 or 12 hours.
Whenever the pots were worked out, that frit was immediately
transferred into them in its ignited state, and the founding process
proceeded with such despatch that this first charge of materials was
completely melted down in 6 hours, so that the pots might admit to be
filled up again with the second charge of frit, which was founded in 4
hours more. The heat was briskly continued, and in the course of from 12
to 18 hours, according to the size of the pots, the quality of the fuel,
and the draught of the furnace, the vitrification was complete. Before
blowing the bottles, however, the glass must be left to settle, and to
cool down to the blowing consistency, by shutting the _cave_ doors and
feeding holes, so as to exclude the air from the fire-grate and the
bottom of the hearth. The glass or metal becomes more dense, and by its
subsidence throws up the foreign lighter earthy and saline matters in
the form of a scum on the surface, which is removed with skimming irons.
The furnace is now charged with coal, to enable it to afford a working
heat for 4 or 5 hours, at the end of which time more fuel is cautiously
added, to preserve adequate heat for finishing the _journey_.

It is hardly possible to convey in words alone a correct idea of the
manipulations necessary to the formation of a wine bottle; but as the
manufacturers make no mystery of this matter, any person may have an
opportunity of inspecting the operation. Six people are employed at this
task; one, called a gatherer, dips the end of an iron tube, about five
feet long, previously made red-hot, into the pot of melted _metal_,
turns the rod round so as to surround it with glass, lifts it out to
cool a little, and then dips and turns it round again; and so in
succession till a ball is formed on its end sufficient to make the
required bottle. He then hands it to the blower, who rolls the plastic
lump of glass on a smooth stone or cast-iron plate, till he brings it to
the very end of the tube; he next introduces the pear-shaped ball into
an open brass or cast-iron mould, shuts this together by pressing a
pedal with his foot, and holding his tube vertically, blows through it,
so as to expand the cooling glass into the form of the mould. Whenever
he takes his foot from the pedal-lever, the mould spontaneously opens
out into two halves, and falls asunder by its bottom hinge. He then
lifts the bottle up at the end of the rod, and transfers it to the
finisher, who, touching the glass-tube at the end of the pipe with a
cold iron, cracks off the bottle smoothly at its mouth-ring. The
finished bottles are immediately piled up in the hot annealing arch,
where they are afterwards allowed to cool slowly for 24 hours at least.
See BOTTLE MOULD.

2. _Broad or spread window glass._--This kind of glass is called
_inferior_ window glass, in this country, because coarse in texture, of
a wavy wrinkled surface, and very cheap, but on the Continent _spread_
window glass, being made with more care, is much better than ours,
though still far inferior in transparency and polish to crown glass,
which has, therefore, nearly superseded its use among us. But Messrs.
Chance and Hartley, of West Bromwich near Birmingham, have of late years
mounted a spread-glass work, where they make _British sheet glass_, upon
the best principles, and turn out an article quite equal, if not
superior to any thing of the kind made either in France or Belgium.
Their materials are those used in the crown-glass manufacture. The
vitrifying mixture is fritted for 20 or 30 hours in a reverberatory
arch, with considerable stirring and puddling with long-handled shovels
and rakes; and the frit is then transferred by shovels while red hot, to
the melting pots to be founded. When the glass is rightly vitrified,
settled, and brought to a working heat, it is lifted out by iron tubes,
as will be described under the article CROWN GLASS, blown into pears,
which being elongated into cylinders, are cracked up along one side,
parallel to the axis, by touching them with a cold iron dipped in water,
and are then opened out into sheets. Glass cylinders are spread in
France, and at West Bromwich, on a bed of smooth stone Paris-plaster, or
laid on the bottom of a reverberatory arch; the cylinder being placed on
its side horizontally, with the cracked line uppermost, gradually opens
out, and flattens on the hearth. At one time, thick plates were thus
prepared for subsequent polishing into mirrors; but the glass was never
of very good quality; and this mode of making mirror-plate has
accordingly been generally abandoned.

The spreading furnace or oven is that in which cylinders are expanded
into tables or plates. It ought to be maintained at a brisk red heat, to
facilitate the softening of the glass. The oven is placed in immediate
connection with the annealing arch, so that the tables may be readily
and safely transferred from the former to the latter. Sometimes the
cylinders are spread in a large muffle furnace, in order to protect them
from being tarnished by sulphureous and carbonaceous fumes.

[Illustration: 500 501]

_Fig._ 500. represents a ground plan of both the spreading and annealing
furnace; _fig._ 501. is an oblong profile in the direction of the dotted
line X X, _fig._ 500.

_a_ is the fire-place; _b b_ the canals or flues through which the flame
rises into both furnaces; _c_ the spreading furnace, upon whose sole is
the spreading slab. _d_ is the cooling and annealing oven; _e e_ iron
bars which extend obliquely across the annealing arch, and serve for
resting the glass tables against, during the cooling. _f f_ the channel
along which the previously cracked cylinders are slid, so as to be
gradually warmed; _g_ the opening in the spreading furnace, for
enabling the workmen to regulate the process; _h_ a door in the
annealing arch, for introducing the tools requisite for raising up and
removing the tables.

[Illustration: 502]

In forming glass-plates by the extension of a cylinder into a plane, the
workman first blows the lump of glass into the shape of an oblong pear,
the length of which must be nearly equal to the length of the intended
plate, and its diameter such, that the circumference when developed,
will be equal to the breadth of the plate. He now rests the blowing-iron
on a stool or iron bar, while an assistant with a pointed iron, pierces
a hole into the extreme end of the pear, in the line of the
blowing-pipe. This opening is then enlarged, by introducing the blade of
a pair of spring-tongs, while the glass is turned round; and by skilful
management, the end of the pear is eventually opened out into a
cylindrical mouth. The workman next mounts upon a stool, and holds the
blowing-iron perpendicularly. The blown cylinder is now cracked off, a
punto rod of iron having been previously stuck to its one end, to form a
spindle for working the other by. This rod has a flat disc on its end,
or three prongs, which being dipped in melted glass, are applied to the
mouth of the cylinder. By this as a handle, the glass cone is carried to
the fire, and the narrow end being heated, is next opened by spring
tongs, and formed into a cylinder of the same size as the other end. The
cylinder thus equalized, is next cracked or slit down in its side with a
pair of shears, laid on a smooth copper plate, detached from the iron
rod, spread out by heat into a plane surface, and finally annealed. This
series of transformations, is represented in _fig._ 502., at A, B, C, D,
E, F, G, H.

[Illustration: 503 504]

_Fig._ 503. and 504. represent a Bohemian furnace in which excellent
white window glass is founded. _Fig._ 503. is a longitudinal section of
the glass and annealing furnace. _Fig._ 504. is the ground plan. _a_ is
the ash pit vaulted under the sole of the furnace; the fireplace itself
is divided into three compartments; with a middle slab at _d_, which is
hollowed in the centre, for collecting any spilt glass, and two hearth
tiles or slabs _b b_. _c c_ are the draught or air holes; _e e_ are
arches upon which the bearing slabs _f f_ partly rest. In the middle
between these arches, the flame strikes upwards upon the pots _g g_,
placed as closely together as possible, for economy of room. _h_ is the
breast wall of the furnace; _i_, _fig._ 504., the opening through which
the pots are introduced; it is bricked up as soon as they are set. _k
k_, is the base of the cone or dome of the furnace; _l l l_, the working
orifices, which are made larger or smaller according to the size of the
glass articles to be made. _m_ is the flue which leads to the annealing
stove _n_, with an arched door. Exterior to this, there is usually a
drying kiln not shown in the figure; and there are adjoining stoves
called _arches_, for drying and annealing the new pots before they are
set.

The cooling or annealing arch, or leer, is often built independent of
the glass-house furnace, is then heated by a separate fire-place, and
constructed like a very long reverberatory furnace. See COPPER.

The leer pans or trays of sheet iron, are laid upon its bottom in an
oblong series, and hooked to each other.

[Illustration: 505]

3. _Crown-glass._--The crown-glass house with its furnace is represented
in _fig._ 505., where the _blowing_ operation is shewn on the one side
of the figure, and the _flashing_ on the other. The furnace is usually
constructed to receive 4 or 6 pots, of such dimensions as to make about
a ton of glass each at a time. There are, however, several subsidiary
furnaces to a crown-house. 1. A reverberatory furnace or _calcar_, for
calcining or fritting the materials; 2. a blowing furnace, for blowing
the pear-shaped balls made at the pot-holes, into large globes; 3. a
flashing furnace, and bottoming hole for communicating a softening heat,
in expanding the globe into a circular plate; 4. the annealing arch for
the finished tables; 5. the reverberatory oven for annealing the pots
prior to their being set upon the founding _siege_.

The materials of crown glass used to be, fine sand, by measure 5 parts,
or by weight 10; ground kelp by measure 11 parts, or by weight 16-1/2;
but instead of kelp, soda ash is now generally employed. From 6 to 8
cwt. of sand, lime, and soda-ash, mixed together in wooden boxes with a
shovel, are thrown on the sole of a large reverberatory, such as is
represented in the article COPPER. Here the mixture is well worked
together, with iron paddles, flat shovels, and rakes with long handles;
the area of this furnace being about 6 feet square, and the height 2
feet. The heat soon brings the materials to a pasty consistence, when
they must be diligently turned over, to favour the dissipation of the
carbon, sulphur, and other volatile matters of the kelp or soda ash, and
to incorporate the fixed ingredients uniformly with the sand. Towards
the end of 3 hours, the fire is considerably raised, and when the fourth
hour has expired, the fritting operation is finished. The mass is now
shovelled or raked out into shallow cast-iron square cases, smoothed
down, and divided before it hardens by cooling, into square lumps, by
cross sections with the spade. These frit-bricks are afterwards piled up
in a large apartment for use; and have been supposed to improve with
age, by the efflorescence of their saline constituents into carbonate of
soda on their surface.

The founding-pots are filled up with these blocks of frit, and the
furnace is powerfully urged by opening all the subterranean passages to
its grate, and closing all the doors and windows of the glass-house
itself. After 8 or 10 hours the vitrification has made such progress,
and the blocks first introduced are so far melted down, that another
charge of frit can be thrown in, and thus the pot is fed with frit till
the proper quantity is used. In about 16 hours the vitrification of the
frit has taken place, and a considerable quantity, amounting often to
the cwt. of liquid saline matter floats over the glass. This salt is
carefully skimmed off into iron pots with long ladles. It is called
Sandiver or Glass-gall, and consists usually of muriate of soda, with a
little sulphate. The pot is now ready for receiving the _topping of
cullet_, which is broken pieces of window glass, to the amount of 3 or 4
cwt. This is shovelled in at short intervals; and as its pressure forces
up the residuary saline matter, this is removed; for were it allowed to
remain, the body of the glass would be materially deteriorated.

The heat is still continued for several hours till the glass is perfect,
and the extrication of gas called the _boil_, which accompanies the
fusion of crown glass, has nearly terminated, when the fire is abated,
by shutting up the lower vault doors and every avenue to the grate, in
order that the glass may settle fine. At the end of about 40 hours
altogether, the fire being slightly raised by adding some coals, and
opening the doors, the glass is carefully skimmed, and the working of
the pots commences.

[Illustration: 506]

Before describing it, however, we may state that the marginal figure
506. shews the base of the crown-house cone, with the four open pots in
two ranges on opposite sides of the furnace, sitting on their raised
_sieges_, at each side of the grate. At one side of the base the door of
the vault is shewn, and its course is marked by the dotted lines.

[Illustration: 507 508]

_Detailed description of the crown-glass furnace_, _figs._ 507. 508.--It
is an oblong square, built in the centre of a brick cone, large enough
to contain within it, two or three pots at each side of the grate room,
which is either divided as shown in the plan, or runs the whole length
of the furnace, as the manufacturer chooses. _Fig._ 507. is a ground
plan, and _fig._ 508. a front elevation, of a six-pot furnace. 1, 2, 3,
_fig._ 507., are the working holes for the purposes of ventilation, of
putting in the materials, and of taking out the metal to be wrought. 4,
5, 6, 7, are pipe holes for warming the pipes before beginning to work
with them. 8, 9, 10, are foot holes for mending the pots and sieges. 11
is a bar of iron for binding the furnace, and keeping it from swelling.

The arch is of an elliptic form; though a barrel arch, that is, an arch
shaped like the half of a barrel cut longwise through the centre, is
sometimes used. But this soon gives way when used in the manufacture of
crown glass, although it does very well in the clay-furnace used for
bottle houses.

The best stone for building furnaces is fire-stone, from Coxgreen in the
neighbourhood of Newcastle. Its quality is a close grit, and it contains
a greater quantity of talc than the common fire-stone, which seems to be
the chief reason of its resisting the fire better. The great danger in
building furnaces is, lest the cement at the top should give way with
the excessive heat, and by dropping into the pots, spoil the metal. The
top should therefore be built with stones only, as loose as they can
hold together after the centres are removed, and without any cement
whatever. The stones expand and come quite close together when
annealing; an operation which takes from eight to fourteen days at most.
There is thus less risk of any thing dropping from the roof of the
furnace.

The inside of the square of the furnace is built either of Stourbridge
fire-clay annealed, or the Newcastle fire-stone, to the thickness of
sixteen inches. The outside is built of common brick about nine inches
in thickness.

The furnace is thrown over an ash-pit, or cave as it is called, which
admits the atmospheric air, and promotes the combustion of the furnace.
This cave is built of stone until it comes beneath the grate room, when
it is formed of fire-brick. The abutments are useful for binding and
keeping the furnace together, and are built of masonry. The furnaces are
stoutly clasped with iron all round, to keep them tight. In four-pot
furnaces this is unnecessary, provided there be four good abutments.

[Illustration: 509]

_Fig._ 509. is an elevation of the flashing furnace. The outside is
built of common brick, the inside of fire-brick, and the mouth or nose
of Stourbridge fire-clay.

[Illustration: 510]

_Fig._ 510. is the annealing kiln. It is built of common brick, except
round the grate room, where fire-brick is used.

[Illustration: 511]

Few tools are needed for blowing and flashing crown-glass. The requisite
ball of plastic glass is gathered, in successive layers as for bottles,
on the end of an iron tube, and rolled into a pear-shape, on a cast-iron
plate; the workman taking care that the air blown into its cavity is
surrounded with an equal body of glass, and if he perceives any side to
be thicker than another, he corrects the inequality by rolling it on the
sloping iron table called marver, (marbre). He now heats the bulb in the
fire, and rolls it so as to form the glass upon the end of the tube,
and by a dexterous swing or two he lengthens it, as shewn in I, _fig._
511. To extend the neck of that pear, he next rolls it over a smooth
iron rod, turned round in a horizontal direction, into the shape K,
_fig._ 511. By further expansion at the blowing-furnace, he now brings
it to the shape L, represented in _fig._ 511.

This spheroid having become cool and somewhat stiff, is next carried to
the bottoming hole (like _fig._ 509.), to be exposed to the action of
flame. A slight wall erected before one half of this hole, screens the
workman from the heat, but leaves room for the globe to pass between it
and the posterior wall. The blowing-pipe is made to rest a little way
from the neck of the globe, on a hook fixed in the front wall; and thus
may be made easily to revolve on its axis, and by giving centrifugal
force to the globe, while the bottom of it, or part opposite to the
pipe, is softened by the heat, it soon assumes the form exhibited in M,
_fig._ 511.

In this state the flattened globe is removed from the fire, and its rod
being rested on the _casher box_ covered with coal cinders, another
workman now applies the end of a solid iron rod tipped with melted
glass, called a _punto_, to the nipple or prominence in the middle; and
thus attaches it to the centre of the globe, while the first workman
cracks off the globe by touching its tubular neck with an iron chisel
dipped in cold water. The workman having thereby taken possession of the
globe by its bottom or knobbed pole attached to his punty rod, he now
carries it to another circular opening, where he exposes it to the
action of moderate flame with regular rotation, and thus slowly heats
the thick projecting remains of the former neck, and opens it slightly
out, as shewn at N, in _fig._ 511. He next hands it to the _flasher_,
who resting the iron rod in a hook placed near the side of the orifice
A, _fig._ 509., wheels it rapidly round opposite to a powerful flame,
till it assumes first the figure O, and finally that of a flat circular
table.

The flasher then walks off with the table, keeping up a slight rotation
as he moves along, and when it is sufficiently cool, he turns down his
rod into a vertical position, and lays the table flat on a dry block of
fire-clay, or bed of sand, when an assistant nips it off from the
_punto_ with a pair of long iron shears, or cracks it off with a touch
of cold iron. The loose table or plate is lastly lifted up horizontally
on a double pronged iron fork, introduced into the annealing arch _fig._
510. and raised on edge; an assistant with a long-kneed fork preventing
it from falling too rapidly backwards. In this arch a great many tables
of glass are piled up in iron frames, and slowly cooled from a heat of
about 600° to 100° F., which takes about 24 hours; when they are
removed. A circular plate or table of about 5 feet diameter weighs on an
average 9 pounds.

4. _Flint glass._--This kind of glass is so called because originally
made with calcined flints, as the siliceous ingredient. The materials at
present employed in this country for the finest flint glass or crystal,
are first, Lynn sand, calcined, sifted, and washed; second, an oxide of
lead, either red lead or litharge; and third, pearl ash. The pearl ash
of commerce must however be purified by digesting it in a very little
hot water, which dissolves the carbonate of potash, and leaves the
foreign salts, chiefly sulphate of potash, muriate of potash, and
muriate of soda. The solution of the carbonate being allowed to cool and
become clear in lead pans, is then run off into a shallow iron boiler,
and evaporated to dryness. Nitre is generally added as a fourth
ingredient of the body of the glass; and it serves to correct any
imperfections which might arise from accidental combustible particles,
or from the lead being not duly oxidized. The above four substances
constitute the main articles; to which we may add arsenic and manganese,
introduced in very small quantities, to purify the colour and clear up
the transparency of the glass. The black oxide of manganese, when used
in such quantity only as to peroxidize the iron of the sand, simply
removes the green tinge caused by the iron; but if more manganese be
added than accomplishes that purpose, it will give a purple tinge to the
glass; and in fact, most manufacturers prefer to have an excess rather
than a defect of manganese, since cut glass has its brilliancy increased
by a faint lilac hue. The arsenic is supposed to counteract the injury
arising from excess of manganese, but is itself very apt on the other
hand to communicate some degree of opalescence, or at least, to impair
the lustre of the glass. When too much manganese has been added, the
purple tinge may indeed be removed by any carbonaceous matter, as by
thrusting a wooden rod down into the liquid glass; but this cannot be
done with good effect in practice, since the final purple tinge is not
decided till the glass is perfectly formed, and then the introduction of
charcoal would destroy the uniformity of the whole contents of the pot.

The raw materials of flint glass, are always mixed with about a third or
a fourth of their weight of broken crystal of like quality; this mixture
is thrown into the pot with a shovel; and more is added whenever the
preceding portions by melting subside; the object being to obtain a pot
full of glass, to facilitate the skimming off the impurities, and
sandiver. The mouth of the pot is now shut, by applying clay-lute round
the stopper, with the exception of a small orifice below, for the escape
of the liquid saline matter. Flint glass requires about 48 hours for its
complete vitrification, though the materials be more fusible than those
of crown glass; in consequence of the contents of the pot being
partially screened by its cover from the action of the fire, as also
from the lower intensity of the heat.

[Illustration: 512 513]

_Fig._ 512. represents a flint glass house for 6 pots, with the arch or
leer on one side for annealing the crystal ware. In _fig._ 513., the
base of the cone is seen, and the glass pots _in situ_ on their platform
ranged round the central fire grate. The dotted line denotes the contour
of the furnace, _fig._ 512.

Whenever the glass appears fine, and is freed from its air bubbles,
which it usually is in about 36 hours, the heat is suffered to fall a
little by closing the bottom valves, &c., that the pot may settle; but
prior to working the metal, the heat is _somewhat raised_ again.

It would be useless to describe the manual operations of fashioning the
various articles of the flint-glass manufacture, because they are
indefinitely varied to suit the conveniences and caprices of human
society.

Every different flint-house has a peculiar proportion of glass
materials. The following have been offered as good practical mixtures.

  1. Fine white sand        300 parts.
     Red lead or litharge   200
     Refined pearl ashes     80
     Nitre                   20
     Arsenic and manganese, a minute quantity.

In my opinion, the proportion of lead is too great in the above recipe,
which is given on the authority of Mr. James Geddes, of Leith. The glass
made with it would be probably yellowish, and dull.

  2. Fine sand                                         50·5
     Litharge                                          27·2
     Refined pearl ashes (carbonate of potash, with 5
     per cent. of water)                               17·5
     Nitre                                              4·8
                                                      -----
                                                      100·0

To these quantities from 30 to 50 parts of broken glass or cullet are
added; with about a two-thousandth part of manganese, and a
three-thousandth part of arsenic. But manganese varies so extremely in
its purity, and contains often so much oxide of iron, that nothing can
be predicated as to its quantity previously to trial.

M. Payen, an eminent manufacturing chemist in France, says that the
composition of crystal does not deviate much from the following
proportions:--

                          Wood fire.      Coal fire.
  Siliceous sand            3               3
  Minium                    2               2-1/4
  Carbonate of potash       1-1/2           1-2/3

I conceive that this glass contains too much lead and potash. Such a
mixture will produce a dull metal, very attractive of moisture: defects
to which the French crown-glass also is subject.

The flint-glass _leer_ for annealing glass, is an arched gallery or
large flue, about 36 feet long, 3 feet high, 4 wide; having its floor
raised above 2 feet above the ground of the glass-house. The hot air and
smoke of a fire-place at one end pass along this gallery, and are
discharged by a chimney 8 or 10 feet short of the other end. On the
floor of the vault, large iron trays are laid and hooked to each other
in a series, which are drawn from the fire end towards the other by a
chain, wound about a cylinder by a winch-handle projecting through the
side. The flint-glass articles are placed in their hot state into the
tray next the fire, which is moved onwards to a cooler station whenever
it is filled, and an empty tray is set in its place. Thus, in the course
of about 20 hours, the glass advances to the cool end thoroughly
annealed.

Besides colourless transparent glass, which forms the most important
part of this manufacture, various coloured glasses are made to suit the
taste of the public. The taste at Paris was lately for opaline crystal;
which may be prepared by adding to the above composition (No. 2.)
phosphate of lime, or well burnt bone-ash in fine powder, washed, and
dried. The article must be as uniform in thickness as possible, and
speedily worked into shape, with a moderate heat. Oxide of tin, _putty_,
was formerly used for making opalescent glass, but the lustre of the
body was always impaired by its means.

Crystal vessels have been made recently of which the inner surface is
colourless, and all the external facets coloured. Such works are easily
executed. The end of the blowing-rod must be dipped first in the pot
containing colourless glass, to form a bulb of a certain size, which
being cooled a little is then dipped for an instant into the pot of
coloured glass. The two layers are associated without intermixture; and
when the article is finished in its form, it is white within and
coloured without. Fluted lines somewhat deeply cut, pass through the
coloured coat, and enter the colourless one; so that when they cross,
their ends alone are coloured.

For some time past, likewise, various crystal articles have been
exhibited in the market with coloured enamel-figures on their surface,
or with white incrustations of a silvery lustre in their interior. The
former are prepared by placing the enamel object in the brass mould, at
the place where it is sought to be attached. The bulb of glass being put
into the mould, and blown while very hot, the small plate of enamel gets
cemented to the surface. For making the white argentine incrustations,
small figures are prepared with an impalpable powder of dry porcelain
paste, cemented into a solid by means of a little gypsum plaster. When
these pieces are thoroughly dried, they are laid on the glass while it
is red hot, and a large patch of very liquid glass is placed above it,
so as to encase it and form one body with the whole. In this way the
incrustation is completely enclosed; and the polished surface of the
crystal which scarcely touches it, gives a brilliant aspect, pleasing to
the eye.

An uniform flint-glass, free from striæ, or _wreath_, is much in demand
for the optician. It would appear that such an article was much more
commonly made by the English manufacturers many years ago, than at
present; and that in improving the brilliancy of crystal-glass they have
injured its fitness for constructing optical lenses, which depends not
so much on its whiteness and lustre as on the layers of different
densities being parallel to each other. The oxide of lead existing in
certain parts of a potful of glass in greater proportion than in other
parts, increases the density unequally in the same mass, so that the
adjoining strata are often very different in this respect. Even a potful
of pretty uniform glass, when it stands some time liquid, becomes
eventually unequable by the subsidence of the denser portions; so that
striæ and gelatinous appearances begin to manifest themselves, and the
glass becomes of little value. Glass allowed to cool slowly in mass in
the pot is particularly full of wreath; and if quickly refrigerated,
that is in two or three hours, it is apt to split into a multitude of
minute splinters, of which no use can be made. For optical purposes, the
glass must be taken out in its liquid state, being gathered on the end
of the iron rod from the central portion of a recently skimmed pot,
after the upper layers have been worked off in general articles.

M. Guinand, of Brennets near Geneva, appears to have hit upon processes
that furnished almost certainly pieces of flint-glass capable of forming
good lenses of remarkable dimensions, even of 11 inches diameter; of
adequate density and transparency, and nearly free from _striæ_. M.
Cauchoix, the eminent French optician, says, that out of ten object
glasses, 4 inches in diameter, made with M. Guinand’s flint-glass, eight
or nine turned out very good, while out of an equal number of object
glasses made of the flint-glass of the English and French manufactories,
only one, or two at most, were found serviceable. The means by which M.
Guinand arrived at these results have not been published. He has lately
died, and it is not known whether his son be in possession of his
secret.

An achromatic object glass for telescopes and microscopes consists of at
least two lenses; the one made with glass of lead, or flint glass, and
the other with crown glass; the former possessing a power of dispersing
the coloured rays relatively to its mean refractive power, much greater
than the latter; upon which principle, the achromatism of the image is
produced, by re-uniting the different coloured rays into one focus.
Flint glass to be fit for this delicate purpose must be perfectly
homogeneous, or of uniform density throughout its substance, and free
from wavy veins or wreathes; for every such inequality would occasion a
corresponding inequality in the refraction and dispersion of the light;
like what is perceived in looking through a thick and thin solution of
gum Arabic imperfectly mixed. Three plans have been prescribed for
obtaining homogeneous pieces of optical glass: 1. to lift a mass of it
in large ladles, and let it cool in them; 2. to pour it out from the
pots into moulds; 3. to allow it to cool in the pots, and afterwards to
cut it off in horizontal strata. The last method, which is the most
plausible, seldom affords pieces of uniform density, unless peculiar
precautions have been adopted to settle the flint glass in uniform
strata; because its materials are of such unequal density, the oxide of
lead having a specific gravity of 8, and silica of 2·7, that they are
apt to stand at irregular heights in the pots.

One main cause of these inequalities lies in the construction of the
furnace, whereby the bottom of the pot is usually much less heated than
the upper part. In a plate glass furnace the temperature of the top of
the pot has been found to be 130° Wedgew., while that of the bottom was
only 110°, constituting a difference of no less than 2610° F. The
necessary consequence is that the denser particles which subside to the
bottom, during the fusion of the materials, and after the first
extrication of the gases, must remain there, not being duly agitated by
the expansive force of caloric, acting from below upwards.

The preparation of the best optical glass is now made a great mystery by
one or two proficients. The following suggestions, deduced from a
consideration of principles, may probably lead to some improvements, if
judiciously applied. The great object is to counteract the tendency of
the glass of lead to distribute itself into strata of different
densities; which may be effected either by mechanical agitation or by
applying the greatest heat to the bottom of the pot. But however
homogeneous the glass may be thereby made, its subsequent separation
into strata of different densities must be prevented by rapid cooling
and solidification. As the deeper the pots, the greater is the chance of
unequal specific gravity in their contents, it would be advisable to
make them wider and shallower than those in use for making ordinary
glass. The intermixture may be effected either by lading the glass out
of one pot into another in the furnace, and back again, with copper
ladles, or by stirring it up with a rouser, then allowing it to settle
for a short time, till it becomes clear and free from air bubbles. The
pot may now be removed from the furnace, in order to solidify its
contents in their homogeneous state; after which the glass may be broken
in pieces, and be perfected by subjecting it to a second fusion; or what
is easier and quicker, we may form suitable discs of glass without
breaking down the potful, by lifting it out in flat copper ladles with
iron shanks, and transferring the lumps after a little while into the
annealing leer.

To render a potful of glass homogeneous by agitation, is a more
difficult task, as an iron rod would discolour it, and a copper rod
would be apt to melt. An iron rod sheathed in laminated platinum would
answer well, but for its expense. A stone-ware tube supported within by
a rod of iron, might also be employed for the purpose in careful hands;
the stirring being repeated several times, till at last the glass is
suffered to stiffen a little by decrease of temperature. It must be then
allowed to settle and cool, after which the pot, being of small
dimensions, may be drawn out of the fire.

[Illustration: 514]

2. The second method of producing the desired uniformity of mixture,
consists in applying a greater heat to the bottom than to the upper part
of the melting pot. _Fig._ 514. represents in section a furnace
contrived to effect this object. It is cylindrical, and of a diameter no
greater than to allow the flames to play round the pot, containing from
three to four cwts. of vitreous materials. A is the pot, resting upon
the arched grid _b a_, built of fire-bricks, whose apertures are wide
enough to let the flames rise freely, and strike the bottom and sides of
the vessel. From 1-1/2 to 2 feet under that arch, the fuel grate _c d_
is placed. B C are the two working openings for introducing the
materials, and inspecting the progress of the fusion; they must be
closed with fire-tiles and luted with fire-clay at the beginning of the
process. At the back of the furnace, opposite the mouth of the
fire-place, there is a door-way, which is bricked up, except upon
occasion of putting in and taking out the pot. The draught is regulated
by means of a slide-plate upon the mouth of the ash-pit _f_. The pot
being heated to the proper pitch, some purified pearl ash, mixed with
fully twice its weight of colourless quartz sand, is to be thrown into
it, and after the complete fusion of this mixture, the remaining part of
the sand along with the oxide of lead (fine litharge) is to be strown
upon the surface. These siliceous particles in their descent serve to
extricate the air from the mass. Whenever the whole is fused, the heat
must be strongly urged to ensure a complete uniformity of combination by
the internal motions of the particles. As soon as the glass has been
found by making test phials to be perfectly fine, the fire must be
withdrawn, the two working holes must be opened, as well as the mouths
of the fire-place and ash-pit, to admit free ingress to cooling currents
of air, so as to congeal the liquid mass as quickly as possible; a
condition essential to the uniformity of the glass. It may be worth
while to stir it a little with the pottery rod at the commencement of
the cooling process. The solidified glass may be afterwards detached by
a hammer in conchoidal discs, which after chipping off their edges, are
to be placed in proper porcelain or stone-ware dishes, and exposed to a
softening heat, in order to give them a lenticular shape. Great care
must be taken that the heat thus applied by the muffle furnace be very
equable, for otherwise wreathes might be very readily re-produced in the
discs. A small oven upon the plan of a baker’s, is best fitted for this
purpose, which being heated to dull redness, and then extinguished, is
ready to soften and afterwards anneal the conchoidal pieces.

Guinand’s dense optical flint glass, of specific gravity 3·616, consists
by analysis, of oxide of lead 43·05; silica 44·3; and potash 11·75; but
requires for its formation the following ingredients: 100 pounds of
ground quartz; 100 pounds of fine red lead; 35 pounds of purified
potash; and from 2 to 4 pounds of saltpetre. As this species of glass is
injured by an excess of potash, it should be compounded with rather a
defect of it, and melted by a proportionally higher or longer heat. A
good optical glass has been made in Germany with 7 parts of pure red
lead, 3 parts of finely ground quartz, and 2 parts of calcined borax.

5. _Plate glass._

This, like English crown-glass, has a soda flux, whereas flint-glass
requires potash, and is never of good quality when made with soda. We
shall distribute our account of this manufacture under two heads.

1. The different furnaces and principal machines, without whose
knowledge it would be impossible to understand the several processes of
a plate-glass factory.

2. The materials which enter into the composition of this kind of glass,
and the series of operations which they undergo; devoting our chief
attention to the changes and improvements which long experience,
enlightened by modern chemistry, has introduced into the great
manufactory of Saint-Gobin in France, under the direction of M.
Tassaert. It may however be remarked that the English plate-glass
manufacture derives peculiar advantages from the excellence of its
grinding and polishing machinery.

The clay for making the bricks and pots should be free from lime and
iron, and very refractory. It is mixed with the powder of old pots
passed through a silk sieve. If the clay be very plastic it will bear
its own weight of the powder, but if shorter in quality, it will take
only three-fifths. But before mingling it with the cement of old pots,
it must be dried, bruised, then picked, ground, and finally elutriated
by agitation with water, decantation through a hair sieve, and
subsidence. The clay fluid after passing the sieve is called _slip_
(coulis.)

The furnace is built of dry bricks, cemented with slip, and has at each
of its four angles a peculiar annealing arch, which communicates with
the furnace interiorly, and thence derives sufficient heat to effect in
part, if not wholly, the annealing of the pots, which are always
deposited there a long time before they are used. Three of these arches
exclusively appropriated to this purpose, are called pot-arches. The
fourth is called the _arch of the materials_, because it serves for
drying them before they are founded. Each arch has, moreover, a
principal opening called the throat, another called _bonnard_, by the
French workmen, through which fire may be kindled in the arch itself,
when it was thought to be necessary for the annealing of the pots; a
practice now abandoned. The duration of a furnace is commonly a year, or
at most 14 months; that of the arches is 30 years or upwards, as they
are not exposed to so strong a heat.

In the manufacture of plate-glass two sorts of crucibles are employed,
called the pots and the basins, (_cuvettes_). The first serve for
containing the materials to be founded, and for keeping them a long time
in the melted state. The _cuvettes_ receive the melted glass after it is
refined, and decant it out on the table to be rolled into a plate. Three
pots hold liquid glass for six small basins, or for three large ones,
the latter being employed for making mirrors of great dimensions, that
is, 100 inches long and upwards. Furnaces have been lately constructed
with 6 pots, and 12 cuvettes, 8 of which are small, and 4 large; and
cuvettes of three sizes are made, called _small_, _middling_, and
_large_. The small are perfect cubes, the middling and the large ones
are oblong parallelopipeds. Towards the middle of their height, a notch
or groove, two or three inches broad, and an inch deep, is left, called
the girdle of the cuvette, by which part they are grasped with the
tongs, or rather are clamped in the iron frame. This frame goes round
the four sides of the small cuvettes, and may be placed indifferently
upon all their sides; in the other cuvettes, the girdle extends only
over the two large sides, because they cannot be turned up. See _m_ T,
_fig._ 515., p. 590.

The pot is an inverted truncated cone, like a crown glass pot. It is
about 30 inches high, and from 30 to 32 inches wide, including its
thickness. There is only a few inches of difference between the diameter
of the top and that of the bottom. The bottom is 3 inches thick, and the
body turns gradually thinner till it is an inch at the mouth of the pot.

The large building or factory, of which the melting furnace occupies the
middle space, is called the _halle_ in French. At Ravenhead in
Lancashire it is called the foundry, and is of magnificent dimensions,
being probably the largest apartment under one roof in Great Britain,
since its length is 339 feet, and its breadth 155. The famous _halle_ of
St. Gobin is 174 feet by 120. Along the two side walls of the _halle_,
which are solidly constructed of hewn stone, there are openings like
those of common ovens. These ovens, destined for the annealing of the
newly cast plates, bear the name of _carquaises_. Their soles are raised
two feet and a half above the level of the ground, in order to bring
them into the same horizontal plane with the casting tables. Their
length, amounting sometimes to 30 feet, and their breadth to 20, are
required in order to accommodate 6, 8, or even 10 plates of glass,
alongside of each other. The front aperture is called the throat, and
the back door the little throat (_gueulette_). The carquaise is heated
by means of a fire-place of a square form called a _tisar_, which
extends along its side.

The founding or melting furnace is a square brick building laid on solid
foundations, being from 8 to 10 feet in each of its fronts, and rising
inside into a vault or crown about 10 feet high. At each angle of this
square, a small oven or arch is constructed, likewise vaulted within,
and communicating with the melting furnace by square flues, called
_lunettes_, through which it receives a powerful heat, though much
inferior to that round the pots. The arches are so distributed as that
two of the exterior sides of the furnace stand wholly free, while the
two other sides, on which the arches encroach, offer a free space of
only 3 feet. In this interjacent space, two principal openings of the
furnace, of equal size in each side, are left in the building. These are
called tunnels. They are destined for the introduction of the pots and
the fuel.

On looking through the tunnels into the inside of the furnace, we
perceive to the right hand and the left, along the two _free_ sides, two
low platforms or _sieges_, at least 30 inches in height and breadth. See
_figs._ 506. 508.

These _sieges_ (seats) being intended to support the pots and the
cuvettes filled with heavy materials, are terminated by a slope, which
ensures the solidity of the fire-clay mound. The slopes of the two
sieges extend towards the middle of the furnace so near as to leave a
space of only from 6 to 10 inches between them for the hearth. The end
of this is perforated with a hole sufficiently large to give passage to
the liquid glass of a broken pot, while the rest is preserved by lading
it from the mouth into the adjoining cuvette.

In the two large parallel sides of the furnace, other apertures are left
much smaller than the tunnels, which are called _ouvreaux_ (peep holes).
The lower ones, or the _ouvreaux en bas_, called _cuvette_ openings,
because being allotted to the admission of these vessels, they are
exactly on a level with the surface of the _sieges_, and with the floor
of the _halle._ Plates of cast iron form the thresholds of these
openings, and facilitate the ingress and egress of the cuvettes. The
apertures are arched at top, with hewn stone like the tunnels, and are
18 inches wide when the cuvettes are 16 inches broad.

The upper and smaller apertures, or the higher _ouvreaux_ called the
_lading_ holes, because they serve for transvasing the liquid glass, are
three in number, and are placed 31 or 32 inches above the surface of the
_sieges_. As the pots are only 30 inches high, it becomes easy to work
through these openings either in the pots or the _cuvettes_. The pots
stand opposite to the two pillars which separate the openings, so that a
space is left between them for one or more _cuvettes_ according to the
size of the latter. It is obvious that if the tunnels and _ouvreaux_
were left open, the furnace would not draw or take the requisite
founding heat. Hence the openings are shut by means of fire-tiles. These
are put in their places, and removed by means of two holes left in them,
in correspondence with the two prongs of a large iron fork supported by
an axle and two iron wheels, and terminated by two handles which the
workmen lay hold of when they wish to move the tile.

The closing of the tunnel is more complex. When it is shut or ready for
the firing, the aperture appears built up with bricks and mortar from
the top of the arch to the middle of the tunnel. The remainder of the
door-way is closed; 1. on the two sides down to the bottom, by a small
upright wall, likewise of bricks, and 8 inches broad, called walls of
the _glaye_; 2. by an assemblage of pieces called pieces of the _glaye_,
because the whole of the closure of the tunnel bears the name of
_glaye_. The upper hole, 4 inches square, is called the _tisar_, through
which billets of wood are tossed into the fire. Fuel is also introduced
into the posterior openings. The fire is always kept up on the hearth of
the tunnel, which is, on this account, 4 inches higher than the
furnace-hearth, in order that the glass which may accidentally fall down
on it, and which does not flow off by the bottom hole, may not impede
the combustion. Should a body of glass, however, at any time obstruct
the grate, it must be removed with rakes, by opening the tunnel and
dismounting the fire-tile stoppers of the _glaye_.

Formerly wood fuel alone was employed for heating the melting-furnaces
of the mirror-plate manufactory of Saint-Gobin; but within these few
years, the Director of the works makes use with nearly equal advantage
of pit-coal. In the same establishment, two melting furnaces may be
seen, one of which is fixed with wood, and the other with coals, without
any difference being perceptible in the quality of the glass furnished
by either. It is not true, as has been stated, that the introduction of
pit-coal has made it necessary to work with covered pots in order to
avoid the discoloration of the materials, or that more alkali was
required to compensate for the diminished heat in the covered pots. They
are not now covered when pit-coal is used, and the same success is
obtained as heretofore by leaving the materials two or three hours
longer in the pots and the cuvettes. The construction of the furnaces in
which coal is burned, is the same as that with wood, with slight
modifications. Instead of the close bottomed hearth of the wood furnace,
there is an iron grate in the coal-hearth through which the air enters,
and the waste ashes descend.

When billets of wood were used as fuel, they were well dried beforehand,
by being placed a few days on a frame work of wood called the wheel,
placed two feet above the furnace and its arches, and supported on four
pillars at some distance from the angles of the building.

_Composition of plate-glass._--This is not made now, as formerly, by
random trials. The progress of chemistry, the discovery of a good
process for the manufacture of soda from sea salt, which furnishes a
pure alkali of uniform power, and the certain methods of ascertaining
its purity, have rendered this department of glass-making almost
entirely new, in France. At Saint-Gobin no alkali is employed at present
except artificial crystals of soda, prepared at the manufactory of
Chauny, subsidiary to that establishment. Leaden chambers are also
erected there for the production of sulphuric acid from sulphur. The
first crop of soda crystals is reserved for the plate-glass manufacture,
the other crystals and the mother-water salts are sold to the makers of
inferior glass.

At the mirror-plate works of Ravenhead, near St. Helen’s in Lancashire,
soda crystals, from the decomposition of the sulphate of soda by chalk
and coal, have been also tried, but without equal success as at
Saint-Gobin; the failure being unquestionably due to the impurity of the
alkali. Hence, in the English establishment the soda is obtained by
treating sea-salt with pearl-ash, whence carbonate of soda and muriate
of potash result. The latter salt is crystallized out of the mingled
solution, by evaporation at a moderate heat, for the carbonate of soda
does not readily crystallize till the temperature of the solution fall
below 60° Fahr. When the muriate of potash is thus removed, the alkaline
carbonate is evaporated to dryness.

Long experience at Saint-Gobin has proved that one part of dry carbonate
of soda is adequate to vitrify perfectly three parts of fine siliceous
sand, as that of the mound of Aumont near Senlis, of Alum Bay in the
Isle of Wight, or of Lynn in Norfolk. It is also known that the degree
of heat has a great influence upon the vitrification, and that increase
of temperature will compensate for a certain deficiency of alkali; for
it is certain that a very strong fire always dissipates a good deal of
the soda, and yet the glass is not less beautiful. The most perfect
mirror-plate has constantly afforded to M. Vauquelin in analysis, a
portion of soda inferior to what had been employed in its formation.
Hence, it has become the practice to add for every 100 parts of cullet
or broken plate that is mixed with the glass composition, one part of
alkali, to make up for the loss that the old glass must have
experienced.

To the above mentioned proportions of sand and alkali independently of
the cullet which may be used, dry slaked lime carefully sifted is to be
added to the amount of one seventh of the sand; or the proportion will
be, sand 7 cwt.; quicklime 1 cwt.; dry carbonate of soda 2 cwt. and 37
lbs.; besides cullet. The lime improves the quality of the glass,
rendering it less brittle and less liable to change. The preceding
quantities of materials suitably blended, have been uniformly found to
afford most advantageous results. The practice formerly was to dry that
mixture, as soon as it was made, in the arch for the materials, but it
has been ascertained that this step may be dispensed with, and the small
portion of humidity present is dissipated almost instantly after they
are thrown into the furnace. The coat of glaze previously applied to the
inside of the pot, prevents the moisture from doing them any harm. For
this reason, when the demand for glass at Saint-Gobin is very great, the
materials are neither fritted nor even dried, but shovelled directly
into the pot; this is called founding _raw_. Six workmen are employed in
shovelling-in the materials either fritted or otherwise, for the sake of
expedition, and to prevent the furnace getting cooled. One-third of the
mixture is introduced at first; whenever this is melted, the second
third is thrown in, and then the last. These three stages are called the
first, second, and third fusion or founding.

According to the ancient practice, the founding and refining were both
executed in the pots, and it was not till the glass was refined, that it
was laded into the cuvettes, where it remained only 3 hours, the time
necessary for the disengagement of the air bubbles introduced by the
transvasion, and for giving the _metal_ the proper consistence for
casting. At present, the period requisite for founding and refining, is
equally divided between the pots and the _cuvettes_. The materials are
left 16 hours in the pots, and as many in the _cuvettes_; so that in 32
hours, the glass is ready to be cast. During the last two or three
hours, the fireman or _tiseur_ ceases to add fuel; all the openings are
shut, and the glass is allowed to assume the requisite fluidity; an
operation called _stopping_ the glass, or _performing the ceremony_.

The transfer of the glass into the _cuvettes_, is called _lading_,
(_tréjetage_). Before this is done, the cuvettes are cleared out, that
is, the glass remaining on their bottom, is removed, and the ashes of
the firing. They are lifted red hot out of the furnace by the method
presently to be described, and placed on an iron plate, near a tub
filled with water. The workmen, by means of iron paddles 6 feet long,
flattened at one end and hammered to an edge, scoop out the fluid glass
expeditiously, and throw it into water; the _cuvettes_ are now returned
to the furnace, and a few minutes afterwards the lading begins.

In this operation, ladles of wrought iron are employed, furnished with
long handles, which are plunged into the pots through the upper openings
or lading holes, and immediately transfer their charge of glass into the
buckets. Each workman dips his ladle only three times, and empties its
contents into the cuvette. By these three immersions (whence the term
_tréjeter_ is derived), the large iron spoon is heated so much that when
plunged into a tub full of water, it makes a noise like the roaring of a
lion, which may be heard to a very great distance.

The founding, refining, and _ceremony_, being finished, they next try
whether the glass be ready for casting. With this view, the end of a rod
is dipped into the bucket, which is called _drawing the glass_, the
portion taken up being allowed to run off, naturally assumes a
pear-shape, from the appearance of which, they can judge if the
consistence be proper, and if any air bubbles remain. If all be right,
the _cuvettes_ are taken out of the furnace, and conveyed to the part of
the _halle_ where their contents are to be poured out. This process
requires peculiar instruments and manipulations.

_Casting._--While the glass is refining, that is, coming to its highest
point of perfection, preparation is made for the most important process,
the casting of the plate, whose success crowns all the preliminary
labours and cares. The oven or _carquaise_ destined to receive and
anneal the plate, is now heated by its small fire or _tisar_, to such a
pitch that its sole may have the same temperature as that of the plates,
being nearly red-hot at the moment of their being introduced. An unequal
degree of heat in the _carquaise_ would cause breakage of the glass. The
casting table is then rolled towards the front door or throat, by means
of levers, and its surface is brought exactly to the level of the sole
of the oven.

The table T, _fig._ 515., is a mass of bronze, or now preferably
cast-iron, about 10 feet long, 5 feet broad, and from 6 to 7 inches
thick, supported by a frame of carpentry, which rests on three cast-iron
wheels. At the end of the table opposite to that next to the front of
the oven, is a very strong frame of timber-work, called the puppet or
standard, upon which the bronze roller which spreads the glass is laid,
before and after the casting. This is 5 feet long by 1 foot in diameter;
it is thick in the metal but hollow in the axis. The same roller can
serve only for two plates at one casting, when another is put in its
place, and the first is laid aside to cool; for otherwise the hot roller
would at a third casting, make the plate expand unequally, and cause it
to crack. When the rollers are not in action, they are laid aside in
strong wooden trestles, like those employed by sawyers. On the two sides
of the table in the line of its length, are two parallel bars of bronze,
_t_, _t_, destined to support the roller during its passage from end to
end; the thickness of these bars determines that of the plate. The table
being thus arranged, a crane is had recourse to for lifting the cuvette,
and keeping it suspended, till it be emptied upon the table. This
raising and suspension are effected by means of an iron gib, furnished
with pullies, held horizontally, and which turns with them.

[Illustration: 515]

The tongs T, _fig._ 515., are made of four iron bars, bent into a square
frame in their middle, for embracing the bucket. Four chains proceeding
from the corners of the frame V, are united at their other ends into a
ring which fits into the hook of the crane.

Things being thus arranged, all the workmen of the foundry co-operate in
the manipulations of the casting. Two of them fetch, and place quickly
in front of one of the lower openings, the small cuvette-carriage, which
bears a forked bar of iron, having two prongs corresponding to the two
holes left in the fire-tile door. This fork mounted on the axle of two
cast-iron wheels, extends at its other end into two branches terminated
by handles, by which the workmen move the fork, lift out the tile
stopper, and set it down against the outer wall of the furnace.

The instant these men retire, two others push forward into the opening
the extremity of the tongs-carriage, so as to seize the bucket by the
girdle, or rather to clamp it. At the same time, a third workman is busy
with an iron pinch or long chisel, detaching the bucket from its seat,
to which it often adheres by some spilt glass; whenever it is free, he
withdraws it from the furnace. Two powerful branches of iron united by a
bolt, like two scissor blades, which open, come together, and join by a
quadrant near the other end, form the tongs-carriage, which is mounted
upon two wheels like a truck.

The same description will apply almost wholly to the iron-plate
carriage, on which the bucket is laid the moment it is taken out of the
furnace; the only difference in its construction is, that on the bent
iron bars which form the tail or lower steps of this carriage (in place
of the tongs) is permanently fastened an iron plate, on which the bucket
is placed and carried for the casting.

Whenever the _cuvette_ is set upon its carriage, it must be rapidly
wheeled to its station near the crane. The tongs T above described are
now applied to the girdle, and are then hooked upon the crane by the
suspension chains. In this position the bucket is skimmed by means of a
copper tool called a sabre, because it has nearly the shape of that
weapon. Every portion of the matter removed by the sabre is thrown into
a copper ladle (_poche de gamin_), which is emptied from time to time
into a cistern of water. After being skimmed, the bucket is lifted up,
and brushed very clean on its sides and bottom; then by the double
handles of the suspension-tongs it is swung round to the table, where it
is seized by the workmen appointed to turn it over; the roller having
been previously laid on its ruler-bars, near the end of the table which
is in contact with the annealing oven. The _cuvette_-men begin to pour
out towards the right extremity E of the roller, and terminate when it
has arrived at the left extremity D. While preparing to do so, and at
the instant of casting, two men place within the ruler-bar on each side,
that is between the bar and the liquid glass, two iron instruments
called _hands_, _m_, _m_, _m_, _m_, which prevent the glass from
spreading beyond the rulers, whilst another draws along the table the
wiping bar _c_, _c_, wrapped in linen, to remove dust, or any small
objects which may interpose between the table and the liquid glass.

Whenever the melted glass is poured out, two men spread it over the
table, guiding the roller slowly and steadily along, beyond the limits
of the glass, and then run it smartly into the wooden standard prepared
for its reception, in place of the trestles V, V.

The empty bucket, while still red-hot, is hung again upon the crane, set
on its plate-iron carriage, freed from its tongs, and replaced in the
furnace, to be speedily cleared out anew, and charged with fresh fluid
from the pots. If while the roller glides along, the two workmen who
stand by with picking tools, perceive _tears_ in the matter in advance
of the roller, and can dexterously snatch them out, they are suitably
rewarded, according to the spot where the blemish lay, whether in the
centre, where it would have proved most detrimental, or near the edge.
These tears proceed usually from small portions of semi-vitrified
matter which fall from the vault of the furnace, and from their density
occupy the bottom of the _cuvettes_.

While the plate is still red-hot and ductile, about 2 inches of its end
opposite to the _carquaise_ door is turned up with a tool; this portion
is called the _head of the mirror_; against the outside of this head,
the shovel, in the shape of a rake without teeth, is applied, with which
the plate is eventually pushed into the oven, while two other workmen
press upon the upper part of the head with a wooden pole, eight feet
long, to preserve the plate in its horizontal position, and prevent its
being warped. The plate is now left for a few moments near the throat of
the _carquaise_, to give it solidity; after which it is pushed further
in by means of a very long iron tool, whose extremity is forked like the
letter y, and hence bears that name; and is thereby arranged in the most
suitable spot for allowing other plates to be introduced.

However numerous the manipulations executed from the moment of
withdrawing the _cuvette_ from the furnace, till the cast-plate is
pushed into the annealing oven, I have seen them all performed in less
than five minutes; such silence, order, regularity, and despatch prevail
in the establishment of Saint-Gobin.

When all the plates of the same casting have been placed in the
_carquaise_, it is sealed up, that is to say, all its orifices are
closed with sheets of iron, surrounded and made tight with plastic loam.
With this precaution, the cooling goes on slowly and equably in every
part, for no cooling current can have access to the interior of the
oven.

After they are perfectly cooled, the plates are carefully withdrawn one
after another, keeping them all the while in a horizontal position, till
they are entirely out of the _carquaise._ As soon as each plate is taken
out, one set of workmen lower quickly and steadily the edge which they
hold, while another set raise the opposite edge, till the glass be
placed upright on two cushions stuffed with straw, and covered with
canvas. In this vertical position they pass through, beneath the lower
edge of the plate, three girths or straps each four feet long, thickened
with leather in their middle, and ending in wooden handles; so that one
embraces the middle of the plate, and the other two, the ends. The
workmen, six in number, now seize the handles of the straps, lift up the
glass closely to their bodies, and convey it with a regular step to the
warehouse. Here the head of the plate is first cut off with a diamond
square, and then the whole is attentively examined, in reference to its
defects and imperfections, to determine the sections which must be made
of it, and the eventual size of the pieces. The pairings and small
cuttings detached are set aside, in order to be ground and mixed with
the raw materials of another glass-pot.

The apartment in which the roughing-down and smoothing of the plates is
performed, is furnished with a considerable number of stone tables,
truly hewn and placed apart like billiard tables, in a horizontal
position, about 2 feet above the ground. They are rectangular, and of
different sizes proportional to the dimensions of the plates, which they
ought always to exceed a little. These tables are supported either on
stone pillars or wooden frames, and are surrounded with a wooden board
whose upper edge stands somewhat below their level, and leaves in the
space between it and the stone all round an interval of 3 or 4 inches,
of which we shall presently see the use.

A cast plate, unless formed on a table quite new, has always one of its
faces, the one next the table, rougher than the other; and with this
face the roughing-down begins. With this view, the smoother face is
cemented on the stone table with Paris-plaster. But often instead of one
plate, several are cemented alongside of each other, those of the same
thickness being carefully selected. They then take one or more crude
plates of about one-third or one-fourth the surface of the plate fixed
to the table, and fix it on them with liquid gypsum to the large base of
a quadrangular truncated pyramid of stone; of a weight proportioned to
its extent, or about a pound to the square inch. This pyramidal muller,
if small sized, bears at each of its angles of the upper face a peg or
ball, which the grinders lay hold of in working it; but when of greater
dimension, there is adapted to it horizontally a wheel of slight
construction, 8 or 10 feet in diameter, whose circumference is made of
wood rounded so as to be seized with the hand. The upper plate is now
rubbed over the lower ones, with moistened sand applied between.

This operation is however performed by machinery. The under plate being
fixed or imbedded in stucco, on a solid table, the upper one likewise
imbedded by the same cement in a cast-iron frame, has a motion of
circum-rotation given to it closely resembling that communicated by the
human hand and arm, moist sand being supplied between them. While an
excentric mechanism imparts this double rotatory movement to the upper
plate round its own centre, and of that centre round a point in the
lower plate, this plate placed on a moveable platform changes its
position by a slow horizontal motion, both in the direction of its
length and its breadth. By this ingenious contrivance, which pervades
the whole of the grinding and polishing machinery, a remarkable
regularity of friction and truth of surface is produced. When the plates
are sufficiently worked on one face, they are reversed in the frames,
and worked together on the other. The Paris plaster is usually coloured
red, in order to shew any defects in the glass.

The smoothing of the plates is effected on the same principles by the
use of moist emery washed to successive degrees of fineness, for the
successive stages of the operation; and the polishing process is
performed by rubbers of hat-felt and a thin paste of colcothar and
water. The colcothar, called also crocus, is red oxide of iron prepared
by the ignition of copperas, with grinding and elutriation of the
residuum.

The last part of the polishing process is performed by hand. This is
managed by females, who slide one plate over another, while a little
moistened putty of tin finely levigated is thrown between.

Large mirror-plates are now the indispensable ornaments of every large
and sumptuous apartment; they diffuse lustre and gaiety round them, by
reflecting the rays of light in a thousand lines, and by multiplying
indefinitely the images of objects placed between opposite parallel
planes.

The _silvering_ of _plane_ mirrors consists in applying a layer of
tin-foil alloyed with mercury to their posterior surface. The workshop
for executing this operation is provided with a great many smooth tables
of fine freestone or marble, truly levelled, having round their contour
a rising ledge, within which there is a gutter or groove which
terminates by a slight slope in a spout at one of the corners. These
tables rest upon an axis of wood or iron which runs along the middle of
their length; so that they may be inclined easily into an angle with the
horizon of 12 or 13 degrees, by means of a hand-screw fixed below. They
are also furnished with brushes, with glass rules, with rolls of woollen
stuff, several pieces of flannel, and a great many weights of stone or
cast-iron.

The glass-tinner, standing towards one angle of his table, sweeps and
wipes its surface with the greatest care, along the whole surface to be
occupied by the mirror-plate; then taking a sheet of tin-foil adapted to
his purpose, he spreads it on the table, and applies it closely with a
brush, which removes any folds or wrinkles. The table being horizontal,
he pours over the tin a small quantity of quicksilver, and spreads it
with a roll of woollen stuff; so that the tin-foil is penetrated and
apparently dissolved by the mercury. Placing now two rules, to the right
and to the left, on the borders of the sheet, he pours on the middle a
quantity of mercury sufficient to form every where a layer about the
thickness of a crown piece; then removing with a linen rag the oxide or
other impurities, he applies to it the edge of a sheet of paper, and
advances it about half an inch. Meanwhile another workman is occupied in
drying very nicely the surface of the glass that is to be silvered, and
then hands it to the master workman, who, laying it flat, places its
anterior edge first on the table, and then on the slip of paper; now
pushing the glass forwards, he takes care to slide it along so that
neither air nor any coat of oxide on the mercury can remain beneath the
plate. When this has reached its position, he fixes it there by a weight
applied on its side, and gives the table a gentle slope, to run off all
the loose quicksilver by the gutter and spout. At the end of five
minutes he covers the mirror with a piece of flannel, and loads it with
a great many weights, which are left upon it for 24 hours, under a
gradually increased inclination of the table. By this time the plate is
ready to be taken off the marble table, and laid on a wooden one sloped
like a reading desk, with its under edge resting on the ground, while
the upper is raised successively to different elevations by means of a
cord passing over a pulley in the ceiling of the room. Thus the mirror
has its slope graduated from day to day, till it finally arrives at a
vertical position. About a month is required for draining out the
superfluous mercury from large mirrors; and from 18 to 20 days from
those of moderate size. The sheets of tin-foil being always somewhat
larger than the glass-plate, their edges must be pared smooth off,
before the plate is lifted off the marble table.

_Process for silvering concave mirrors._--Having prepared some very fine
Paris plaster by passing it through a silk sieve, and some a little
coarser passed through hair-cloth, the first is to be made into a creamy
liquor with water, and after smearing the concave surface of the glass
with a film of olive oil, the fine plaster is to be poured into it, and
spread by turning about, till a layer of plaster be formed about a tenth
of an inch thick. The second or coarse plaster, being now made into a
thin paste, poured over the first, and moved about, readily incorporates
with it, in its imperfectly hardened state. Thus an exact mould is
obtained of the concave surface of the glass, which lies about
three-quarters of an inch thick upon it, but is not allowed to rise
above its outer edge.

The mould being perfectly dried, must be marked with a point of
coincidence on the glass, in order to permit of its being exactly
replaced in the same position, after it has been lifted out. The mould
is now removed, and a round sheet of tin-foil is applied to it, so large
that an inch of its edge may project beyond the plaster all round; this
border being necessary for fixing the tin to the contour of the mould by
pellets of white wax softened a little with some Venice turpentine.
Before fixing the tin-foil, however, it must be properly spread over the
mould, so as to remove every wrinkle; which the pliancy of the foil
easily admits of, by uniform and well-directed pressure with the
fingers.

The glass being placed in the hollow bed of a tight sack filled with
fine sand, set in a well-jointed box capable of retaining quicksilver,
its concave surface must be dusted with sifted wood-ashes, or Spanish
white contained in a small cotton bag, and then well wiped with clean
linen rags, to free it from all adhering impurity, and particularly the
moisture of the breath. The concavity must be now filled with
quicksilver to the very lip, and the mould being dipped a little way
into it, is withdrawn, and the adhering mercury is spread over the tin
with a soft flannel roll, so as to amalgamate and brighten its whole
surface, taking every precaution against breathing on it. Whenever this
brightening seems complete, the mould is to be immersed, not vertically,
but one edge at first, and thus obliquely downwards till the centres
coincide; the mercury meanwhile being slowly displaced, and the mark on
the mould being brought finally into coincidence with the mark on the
glass. The mould is now left to operate by its own weight, in expelling
the superfluous mercury, which runs out upon the sand-bag and thence
into a groove in the bottom of the box, whence it overflows by a spout
into a leather bag of reception. After half an hour’s repose, the whole
is cautiously inverted, to drain off the quicksilver more completely.
For this purpose, a box like the first is provided with a central
support rising an inch above its edges; the upper surface of the support
being nearly equal in diameter to that of the mould. Two workmen are
required to execute the following operation. Each steadies the mould
with the one hand, and raises the box with the other, taking care not to
let the mould be deranged, which they rest on the (convex) support of
the second box. Before inverting the first apparatus, however, the
reception bag must be removed, for fear of spilling its mercury. The
redundant quicksilver now drains off; and if the weight of the sand-bag
is not thought sufficient, supplementary weights are added at pleasure.
The whole is left in this position for two or three days. Before
separating the mirror from its mould, the border of tin-foil, fixed to
it with wax, must be pared off with a knife. Then the weight and
sand-bag being removed, the glass is lifted up with its interior coating
of tin-amalgam.

_For silvering a convex surface._--A concave plaster mould is made on
the convex glass, and their points of coincidence are defined by marks.
This mould is to be lined with tin-foil, with the precautions above
described; and the tin surface being first brightened with a little
mercury, the mould is then filled with the liquid metal. The glass is to
be well cleaned, and immersed in the quicksilver bath, which will expel
the greater part of the metal. A sand-bag is now to be laid on the
glass, and the whole is to be inverted as in the former case on a
support; when weights are to be applied to the mould, and the mercury is
left to drain off for several days.

If the glass be of large dimensions, 30 or 40 inches, for example,
another method is adopted. A circular frame or hollow ring of wood or
iron is prepared, of twice the diameter of the mirror, supported on
three feet. A circular piece of new linen cloth of close texture is cut
out, of equal diameter to the ring, which is hemmed stoutly at the
border, and furnished round the edge with a row of small holes, for
lacing the cloth to the ring, so as to leave no folds in it, but without
bracing it so tightly as to deprive it of the elasticity necessary for
making it into a mould. This apparatus being set horizontally, a leaf of
tin-foil is spread over it, of sufficient size to cover the surface of
the glass; the tin is first brightened with mercury, and then as much of
the liquid metal is poured on as a plane mirror requires. The convex
glass, well cleaned, is now set down on the cloth, and its own weight,
joined to some additional weights, gradually presses down the cloth, and
causes it to assume the form of the glass which thus comes into close
contact with the tin submersed under the quicksilver. The redundant
quicksilver is afterwards drained off by inversion, as in common cases.

The following recipe has been given for silvering the inside of glass
globes. Melt in an iron ladle or a crucible, equal parts of tin and
lead, adding to the fused alloy one part of bruised bismuth. Stir the
mixture well and pour into it as it cools two parts of dry mercury;
agitating anew and skimming off the drossy film from the surface of the
amalgam. The inside of the glass globe being freed from all adhering
dust and humidity, is to be gently heated, while a little of the
semi-fluid amalgam is introduced. The liquidity being increased by the
slight degree of heat, the metallic coating is applied to all the points
of the glass, by turning round the globe in every direction, but so
slowly as to favour the adhesion of the alloy. This silvering is not so
substantial as that of plane mirrors: but the form of the vessel,
whether a globe, an ovoid, or a cylinder, conceals or palliates the
defects by counter reflection from the opposite surfaces.

_Coloured Glasses and Artificial Gems._--The general vitreous body
preferred by Fontanieu in his treatise on this subject, which he calls
the Mayence base, is prepared in the following manner. Eight ounces of
pure rock-crystal or flint in powder, mixed with 24 ounces of salt of
tartar, are baked and left to cool. This is afterwards poured into a
basin of hot water, and treated with dilute nitric acid till it ceases
to effervesce; when the frit is to be washed till the water comes off
tasteless. The frit is now dried and mixed with 12 ounces of fine white
lead, and the mixture is to be levigated and elutriated with a little
distilled water. An ounce of calcined borax is to be added to about 12
ounces of the preceding mixture in a dry state, the whole rubbed
together in a porcelain mortar, then melted in a clean crucible, and
poured out into cold water. This vitreous matter must be dried, and
melted a second and a third time, always in a new crucible, and after
each melting poured into cold water as at first, taking care to separate
the lead that may be revived. To the last glass ground to powder, five
drachms of nitre are to be added, and the mixture being melted for the
last time, a mass of crystal will be found in the crucible with a
beautiful lustre. The diamond is well imitated by this Mayence base.
Another very fine white crystal may be obtained, according to M.
Fontanieu, from eight ounces of white lead, two ounces of powdered
borax, half a grain of manganese, and three ounces of rock-crystal
treated as above.

The colours of artificial gems are obtained from metallic oxides. The
_oriental topaz_ is prepared by adding oxide of antimony to the base;
the amethyst from manganese with a little purple precipitate of Cassius;
the beryl from antimony and a very little cobalt; yellow artificial
diamond and opal, from horn-silver (chloride of silver); blue stone from
cobalt. See PASTES and PIGMENTS VITRIFIABLE.

The following are recipes for making the different kinds of glass.

1. _Bottle glass._--11 pounds of dry glauber salts; 12 pounds of soaper
salts; a half bushel of waste soap ashes; 56 pounds of sand; 22 pounds
of glass skimmings; 1 cwt. of green broken glass; 25 pounds of basalt.
This mixture affords a dark green glass.

2. Yellow or white sand 100 parts; kelp 30 to 40; lixiviated wood ashes
from 160 to 170 parts; fresh wood ashes 30 to 40 parts; potter’s clay 80
to 100 parts; cullet or broken glass 100. If basalt be used, the
proportion of kelp may be diminished.

In two bottle-glass houses in the neighbourhood of Valenciennes, an
unknown ingredient, sold by a Belgian, was employed, which he called
_spar_. This was discovered by chemical analysis to be sulphate of
baryta. The glass-makers observed that the bottles which contained some
of this substance were denser, more homogeneous, more fusible, and
worked more kindly, than those formed of the common materials. When one
prime equivalent of the silicate of baryta = 123, is mixed with three
primes of the silicate of soda = (3 × 77·6) = 232·8, and exposed in a
proper furnace, vitrification readily ensues, and the glass may be
worked a little under a cherry-red heat, with as much ease as a glass of
lead, and has nearly the same lustre. Since the ordinary run of
glass-makers are not familiar with atomic proportions, they should have
recourse to a scientific chemist, to guide them in using such a
proportion of sulphate of baryta as may suit their other vitreous
ingredients; for an excess or defect of any of them will injure the
quality of the glass.

3. _Green window glass, or broad glass._--11 pounds of dry glauber salt;
10 pounds of soaper salts; half a bushel of lixiviated soap waste; 50
pounds of sand; 22 pounds of glass pot skimmings; 1 cwt. of broken green
glass.

4. _Crown glass._--300 parts of fine sand; 200 of good soda ash; 33 of
lime; from 250 to 300 of broken glass; 60 of white sand; 30 of purified
potash; 15 of saltpetre (1 of borax), 1/2 of arsenious acid.

5. _Nearly white table glass._--20 pounds of potashes; 11 pounds of dry
glauber salts; 16 of soaper salt; 55 of sand; 140 of cullet of the same
kind. Another.--100 of sand; 235 of kelp; 60 of wood ashes; 1-1/3 of
manganese; 100 of broken glass.

6. _White table glass._--40 pounds of potashes; 11 of chalk; 76 of sand;
1/2 of manganese; 95 of white cullet.

Another.--50 of purified potashes; 100 of sand; 20 of chalk; and 2 of
saltpetre.

Bohemian table or plate glass is made with 63 parts of quartz; 26 of
purified potashes; 11 of sifted slaked lime, and some cullet.

7. _Crystal glass._--60 parts of purified potashes; 120 of sand; 24 of
chalk; 2 of saltpetre; 2 of arsenious acid; 1/16 of manganese.

Another.--70 of purified pearl ashes; 120 of white sand; 10 of
saltpetre; 1/2 of arsenious acid; 1/3 of manganese.

A third.--67 of sand; 23 of purified pearl ashes; 10 of sifted slaked
lime; 1/4 of manganese; (5 to 8 of red lead).

A fourth.--120 of white sand; 50 of red lead; 40 of purified pearl ash;
20 of saltpetre; 1/3 of manganese.

A fifth.--120 of white sand; 40 of pearl ash purified; 35 of red lead;
13 of saltpetre; 1/12 of manganese.

A sixth.--30 of the finest sand; 20 of red lead; 8 of pearl ash
purified; 2 of saltpetre; a little arsenious acid and manganese.

A seventh.--100 of sand; 45 of red lead; 35 of purified pearl ashes; 1/7
of manganese; 1/3 of arsenious acid.

8. _Plate glass._--Very white sand 300 parts; dry purified soda 100
parts; carbonate of lime 43 parts; manganese 1; cullet 300.

Another.--Finest sand 720; purified soda 450; quicklime 80 parts;
saltpetre 25 parts; cullet 425.

A little borax has also been prescribed; much of it communicates an
exfoliating property to glass.

Tabular view of the composition of several kinds of Glass.

  +------------------+----+----+-----+----+----+-----+----+-----+----+
  |                  | No.| No.| No. | No.| No.| No. | No.| No. | No.|
  |                  |  1.| 2. | 3.  | 4. | 5. | 6.  | 7. | 8.  | 9. |
  |                  +----+----+-----+----+----+-----+----+-----+----+
  |Silica            |71·7|69·2| 62·8|69·2|60·4|53·55|59·2|51·93|42·5|
  |Potash            |12·7|15·8| 22·1| 8·0| 3·2| 5·48| 9·0|13·77|11·7|
  |Soda              | 2·5| 3·0|     | 3·0| S. |     |    |     |    |
  |                  |    |    |     |    |pot.|     |    |     |    |
  |Lime              |10·3| 7·6| 12·5|13·0|20·7|29·22|    |     | 0·5|
  |Alumina           | 0·4| 1·2|     | 3·6|10·4| 6·01|    |     | 1·8|
  |Magnesia          |    | 2·0|}    | 0·6| 0·6|     |    |     |    |
  |Oxide of iron     | 0·3| 0·5|} 2·6| 1·6| 3·8| 5·74| 0·4|     |    |
  |   --    manganese| 0·2|    |}    |    |    |     | 1·0|     |    |
  |   --    lead     |    |    |     |    |    |     |28·2|33·28|43·5|
  |Baryta            |    |    |     |    | 0·9|     |    |     |    |
  +------------------+----+----+-----+----+----+-----+----+-----+----+

No. 1. is a very beautiful white wine glass of Neuwelt in Bohemia.

No. 2. Glass tubes, much more fusible than common wine glasses.

No. 3. Crown glass of Bohemia.

No. 4. Green glass, for medicinal phials and retorts.

No. 5. Flask glass of St. Etienne, for which some heavy spar is used.

No. 6. Glass of Sèvres.

No. 7. London glass employed for chemical and physical purposes.

No. 8. English flint glass.

No. 9. Guinand’s flint glass.

The manufacture of _Glass beads_ at Murano near Venice, is most
ingeniously simple. Tubes of glass of every colour, are drawn out to
great lengths in a gallery adjoining the glass-house pots, in the same
way as the more moderate lengths of thermometer and barometer tubes are
drawn in our glass-houses. These tubes are chopped into very small
pieces of nearly uniform length on the upright edge of a fixed chisel.
These elementary cylinders being then put in a heap into a mixture of
fine sand and wood ashes, are stirred about with an iron spatula till
their cavities get filled. This curious mixture is now transferred to an
iron pan suspended over a moderate fire, and continually stirred about
as before, whereby the cylindrical bits assume a smooth rounded form; so
that when removed from the fire and cleared out in the bore, they
constitute beads, which are packed in casks, and exported in prodigious
quantities to almost every country, especially to Africa and Spain.


GLASS CUTTING AND GRINDING, for common and optical purposes. By this
mechanical process the surface of glass may be modified into almost any
ornamental or useful form.

1. The grinding of crystal ware. This kind of glass is best adapted to
receive polished facets, both on account of its relative softness, and
its higher refractive power, which gives lustre to its surface. The
cutting shop should be a spacious long apartment, furnished with
numerous sky-lights, having the grinding and polishing lathes arranged
right under them, which are set in motion by a steam-engine or
water-wheel at one end of the building. A shaft is fixed as usual in
gallowses along the ceiling; and from the pulleys of the shaft, bands
descend to turn the different lathes, by passing round the driving
pulleys near their ends.

[Illustration: 516]

The turning lathe is of the simplest construction. _Fig._ 516. D is an
iron spindle with two well-turned prolongations, running in the iron
puppets _a a_, between two concave bushes of tin or type metal, which
may be pressed more or less together by the thumb-screws shown in the
figure. These two puppets are made fast to the wooden support B, which
is attached by a strong screw and bolt to the longitudinal beam of the
workshop A. E is the fast and loose pulley for putting the lathe into
and out of geer with the driving shaft. The projecting end of the
spindle is furnished with a hollow head-piece, into which the rod _c_ is
pushed tight. This rod carries the cutting or grinding disc plate. For
heavy work, this rod is fixed into the head by a screw. When a conical
fit is preferred, the cone is covered with lead to increase the
friction.

Upon projecting rods or spindles of that kind the different discs for
cutting the glass are made fast. Some of these are made of fine
sandstone or polishing slate, from 8 to 10 inches in diameter, and from
3/4 to 1/2 inch thick. They must be carefully turned and polished at the
lathe, not only upon their rounded but upon their flat face, in order to
grind and polish in their turn the flat and curved surfaces of glass
vessels. Other discs of the same diameter, but only 3/4 of an inch
thick, are made of cast tin truly turned, and serve for polishing the
vessels previously ground; a third set consist of sheet iron from 1/6 to
1/2 an inch thick, and 12 inches in diameter, and are destined to cut
grooves in glass by the aid of sand and water. Small discs of
well-hammered copper from 1/2 to 3 inches in diameter, whose
circumference is sometimes flat, and sometimes concave or convex, serve
to make all sorts of delineations upon glass by means of emery and oil.
Lastly, there are rods of copper or brass furnished with small
hemispheres from 1/24 to 1/4 of an inch in diameter, to excavate round
hollows in glass. Wooden discs are also employed for polishing, made of
white wood cut across the grain, as also of cork.

[Illustration: 517]

The cutting of deep indentations, and of grooves, is usually performed
by the iron disc, with sand and water, which are allowed constantly to
trickle down from a wooden hopper placed right over it, and furnished
with a wooden stopple or plug at the apex, to regulate by its greater or
less looseness the flow of the grinding materials. The same effect may
be produced by using buckets as shown in _fig._ 517. The sand which is
contained in the bucket F, above the lathe, has a spigot and faucet
inserted near its bottom, and is supplied with a stream of water from
the stopcock in the vessel G, which, together running down the inclined
board, are conducted to the periphery of the disc as shown in the
figure, to whose lowest point the glass vessel is applied with pressure
by the hand. The sand and water are afterwards collected in the tub H.
Finer markings which are to remain without lustre, are made with the
small copper discs, emery, and oil. The polishing is effected by the
edge of the tin disc, which is from time to time moistened with putty
(white oxide of tin) and water. The wooden disc is also employed for
this purpose with putty, colcothar, or washed tripoli. For fine
delineations, the glass is first traced over with some coloured varnish,
to guide the hand of the cutter.

In grinding and facetting crystal glass, the deep grooves are first cut,
for example the cross lines, with the iron disc and rounded edge, by
means of sand and water. That disc is one sixth of an inch thick and 12
inches in diameter. With another iron disc about half an inch thick, and
more or less in diameter, according to the curvature of the surface, the
grooves may be widened. These roughly cut parts must be next smoothed
down with the sandstone disc and water, and then polished with the
wooden disc about half an inch thick, to whose edge the workman applies,
from time to time, a bag of fine linen containing some ground pumice
moistened with water. When the cork or wooden disc edged with hat felt
is used for polishing, putty or colcothar is applied to it. The above
several processes in a large manufactory, are usually committed to
several workmen on the principle of the division of labour, so that each
may become expert in his department.

2. _The grinding of optical glasses._--The glasses intended for optical
purposes being spherically ground, are called lenses; and are used
either as simple magnifiers and spectacles, or for telescopes and
microscopes. The curvature is always a portion of a sphere, and either
convex or concave. This form ensures the convergence or divergence of
the rays of light that pass through them, as the polishing does the
brightness of the image.

The grinding of the lenses is performed in brass moulds, either concave
or convex, formed to the same curvature as that desired in the lenses;
and may be worked either by hand or by machinery. A gauge is first cut
out out of brass or copper plate to suit the curvature of the lens, the
circular arc being traced by a pair of compasses. In this way both a
convex and concave circular gauge are obtained. To these gauges the
brass moulds are turned. Sometimes, also, lead moulds are used. After
the two moulds are made, they are ground face to face with fine emery.

The piece of glass is now roughed into a circular form by a pair of
pincers, leaving it a little larger than the finished lens ought to be,
and then smoothed round upon the stone disc, or in an old mould with
emery and water, and is next made fast to a holdfast. This consists of a
round brass plate having a screw in its back; and is somewhat smaller in
diameter than the lens, and two thirds as thick. This as turned concave
upon the lathe, and then attached to the piece of glass by drops of
pitch applied to several points of its surface, taking care while the
pitch is warm, that the centre of the glass coincides with the centre of
the brass plate. This serves not merely as a holdfast, by enabling a
person to seize its edge with the fingers, but it prevents the glass
from bending by the necessary pressure in grinding.

The glass must now be ground with coarse emery upon its appropriate
mould, whether convex or concave, the emery being all the time kept
moist with water. To prevent the heat of the hand from affecting the
glass, a rod for holding the brass plate is screwed to its back. For
every six turns of circular motion, it must receive two or three rubs
across the diameter in different directions, and so on alternately. The
middle point of the glass must never pass beyond the edge of the mould;
nor should strong pressure be at any time applied. Whenever the glass
has assumed the shape of the mould, and touches it in every point, the
coarse emery must be washed away, finer be substituted in its place, and
the grinding be continued as before, till all the scratches disappear,
and a uniform dead surface be produced. A commencement of polishing is
now to be given with pumice-stone powder. During all this time the
convex mould should be occasionally worked in the concave, in order that
both may preserve their correspondence of shape between them. After the
one surface has been thus finished, the glass must be turned over, and
treated in the same way upon the other side.

Both surfaces are now to be polished. With this view equal parts of
pitch and rosin must be melted together, and strained through a cloth to
separate all impurities. The concave mould is next to be heated, and
covered with that mixture in a fluid state to the thickness uniformly of
one quarter of an inch. The cold convex mould is now to be pressed down
into the yielding pitch, its surface being quite clean and dry, in order
to give the pitch the exact form of the ground lens; and both are to be
plunged into cold water till they be chilled. This pitch impression is
now the mould upon which the glass is to be polished, according to the
methods above described with finely washed colcothar and water, till the
surface become perfectly clear and brilliant. To prevent the pitch from
changing its figure by the friction, cross lines must be cut in it about
1/2 an inch asunder, and 1-12th of an inch broad and deep. These grooves
remove all the superfluous parts of the polishing powder, and tend to
preserve the polishing surface of the pitch clean and unaltered. No
additional colcothar after the first is required in this part of the
process; but only a drop of water from time to time. The pitch gets warm
as the polishing advances, and renders the friction more laborious from
the adhesion between the surfaces. No interruption must now be suffered
in the work, nor must either water or colcothar be added; but should the
pitch become too adhesive, it must be merely breathed upon, till the
polish be complete. The nearer the lens is brought to a true and fine
surface in the first grinding, the better and more easy does the
polishing become. It should never be submitted to this process with any
scratches perceptible in it, even when examined by a magnifier.

As to small lenses and spectacle eyes, several are ground and polished
together in a mould about 6 inches in diameter, made fast to a
stiffening plate of brass or iron of a shape corresponding with the
mould. The pieces of glass are affixed by means of drops of pitch as
above described, to the mould, close to each other, and are then all
treated as if they formed but one large lens. Plane glasses are ground
upon a surface of pitch rendered plane by the pressure of a piece of
plate glass upon it in its softened state.

Lenses are also ground and polished by means of machinery, into the
details of which the limits of this work will not allow me to enter.

  A Return to an Order of the Honourable the House of Commons, dated 1st
  March, 1838, of the Amount of Duty charged on Glass; distinguishing
  the Amount charged on Flint, Plate, Broad, Crown, Bottle and German
  Sheet, in the Year ending the 5th day of January, 1838; together with
  the Amount of Drawback on each description of Glass; the produce of
  the Duties in England, Scotland, and Ireland stated separately.

  +----------+--------------+-------------+-------------+--------------+
  |Amount of |              |             |             |              |
  |Duty      |   England    |   Scotland  |   Ireland   |    Total     |
  |charged on|              |             |             |              |
  +----------+--------------+-------------+-------------+--------------+
  |          |  _£.   s. d._| _£.   s. d._| _£.   s. d._|  _£.   s. d._|
  |Flint     |              |             |             |              |
  |Glass.    | 76,052  1  0 | 7,530  9  4 | 6,736 12 11 | 90,319  3  3 |
  |Plate.    | 68,902 10    |             |             | 68,902 10    |
  |Broad.    | 10,789 10    |             |             | 10,789 10    |
  |Crown.    |533,404  6  7 |16,423 11  6 |             |549,827 18  1 |
  |Bottle.   |122,617 10  2 |32,246  4  1 | 3,642  0  3 |158,505 14  6 |
  |German    |              |             |             |              |
  |Sheet.    | 25,511 17    |             |             | 25,511 17    |
  +----------+--------------+-------------+-------------+--------------+
  |Total.    |837,277 14  9 |56,200  4 11 |10,378 13  2 |903,856 12 10 |
  +----------+--------------+-------------+-------------+--------------+

  +--------+--------------+-------------+----------+--------------+
  |Amount  |              |             |          |              |
  |of Draw-|              |             |          |              |
  |back on |    England   |  Scotland   | Ireland  |    Total     |
  |Exporta-|              |             |          |              |
  |tion.   |              |             |          |              |
  +--------+--------------+-------------+----------+--------------+
  |        |  _£.   s. d._| _£.   s. d._|_£. s. d._|  _£.   s. d._|
  |Flint   |              |             |          |              |
  |Glass.  | 15,597  2  7 | 1,726 15  5 |107 14  8 | 17,431 12  8 |
  |Plate.  |  3,983 17  9 |             |          |  3,983 17  9 |
  |Broad.  |      4 10    |             |          |      4 10    |
  |Crown.  |168,892 10  2 | 8,626  9  0 | 10  9  1 |177,529  8  3 |
  |Bottle. | 56,770 10  5 |14,819  8  1 |274 10  5 | 71,864  8 11 |
  |German  |              |             |          |              |
  |Sheet.  | 22,889 17  9 |    32 15  6 |          | 22,922 13  3 |
  +--------+--------------+-------------+----------+--------------+
  |Total.  |268,138  8  8 |25,205  8  0 |392 14  2 |293,736 10 10 |
  +--------+--------------+-------------+----------+--------------+

The duties payable in the United Kingdom, upon the different
descriptions of glass are, for--

                                              _£.   s.   d._
  Flint glass, the finished article             0    0    2  per lb.
  British plate or German sheet, and crown
  glass, ditto                                  3   13    6  per cwt.
  Broad glass, ditto                            1   10    0    --
  Bottles, ditto                                0    7    0    --
  Plate glass, the fused material in pot        3    0    0    --


GLAZES. See POTTERY.


GLAZIER, is the workman who cuts plates, or panes of glass, with the
diamond, and fastens them by means of putty in frames or window
casements. See DIAMOND, for an explanation of its glass-cutting
property.


GLAUBER SALT; is the old name of sulphate of soda.

[Illustration: 518 519 520]


GLOVE MANUFACTURE. In February, 1822, Mr. James Winter of
Stoke-under-Hambdon, in the county of Somerset, obtained a patent for an
improvement upon a former patent machine of his for sewing and pointing
leather gloves. _Fig._ 518. represents a pedestal, upon which the
instrument called the jaws is to be placed. _Fig._ 519. shows the jaws,
which instead of opening and closing by a circular movement upon a
joint, as described in the former specification, are now made to open
and shut by a parallel horizontal movement, effected by a slide and
screw; _a a_ is the fixed jaw, made of one piece, on the under side of
which is a tenon, to be inserted into the top of the pedestal. By means
of this tenon the jaws may be readily removed, and another similar pair
of jaws placed in their stead, which affords the advantage of expediting
the operation by enabling one person to prepare the work whilst another
is sewing; _b b_ is the movable jaw, made of one piece. The two jaws
being placed together in the manner shown at _fig._ 519., the movable
jaw traverses backwards and forwards upon two guide-bars, _c_, which are
made to pass through holes exactly fitted to them, in the lower parts of
the jaws. At the upper parts of the jaws are, what are called the
indexes, _d d_, which are pressed tightly together by a spring, shown at
_fig._ 520., and intended to be introduced between the perpendicular
ribs of the jaws at _e_. At _f_, is a thumb-screw, passing through the
ribs for the purpose of tightening the jaws, and holding the leather
fast between the indexes while being sewn; this screw, however, will
seldom, if ever, be necessary if the spring is sufficiently strong; _g_
is an eye or ring fixed to the movable jaw, through which the end of a
lever _h_, in _fig._ 518., passes; this lever is connected by a spring
to a treadle _i_, at the base of the pedestal, and by the pressure of
the right foot upon this treadle, the movable jaw is withdrawn; so that
the person employed in sewing may shift the leather, and place another
part of the glove between the jaws. The pieces called indexes, are
connected to the upper part of the jaws, by screws passing through
elongated holes which render them capable of adjustment.

[Illustration: 521 522 523 524]

The patentee states, that in addition to the index described in his
former patent, which is applicable to what is called round-seam sewing
only, and which permits the leather to expand but in one direction, when
the needle is passed through it, namely, upwards; he now makes two
indexes of different construction, one of which he calls the receding
index, and the other the longitudinally grooved index. _Fig._ 521.
represents an end view, and _fig._ 522. a top view of the receding
index, which is particularly adapted for what are called “drawn sewing,
and prick-seam sewing;” this index, instead of biting to the top, is so
rounded off in the inside from the bottom of the cross grooves, as to
permit the needles, by being passed backwards and forwards, to carry the
silk thread on each side of the leather without passing over it. _Fig._
523. represents an end view of the longitudinally grooved index, partly
open, to show the section of the grooves more distinctly; and _fig._
524. represents an inside view of one side of the same index, in which
the longitudinal groove is shown passing from _k_ to _l_. This index is
more particularly adapted to round-seam sewing, and permits the leather
to expand in every direction when the needle is passed through it, by
which the leather is less strained, and the sewing consequently rendered
much stronger.

It is obvious that the parallel horizontal movement may be effected by
other mechanical means besides those adopted here, and the chief novelty
claimed with respect to that movement, is its application to the purpose
of carrying the index used in sewing and pointing leather gloves.

Importation of leather gloves for home consumption; and amount of duty
in

    1836.       1837.   |    1836.       1837.
  1,461,769 | 1,221,350 | _£_27,558 | _£_22,923

[Illustration: 525 526 527]


GLOVE-SEWING. The following simple and ingenious apparatus, invented by
an Englishman, has been employed extensively in Paris, and has enabled
its proprietors to realize a handsome fortune. The French complain that
“it has inundated the world with gloves, made of excellent quality, at
30 per cent. under their former wholesale prices.” The instrument is
shown in profile ready for action in _fig._ 525. It resembles an iron
vice, having the upper portion of each jaw made of brass, and tipped
with a kind of comb of the same metal. The teeth of this comb, only one
twelfth of an inch long, are perfectly regular and equal. Change combs
are provided for different styles of work. The vice A A is made fast to
the edge of the bench or table B, of the proper height, by a thumb-screw
C, armed with a cramp which lays hold of the wood. Of the two jaws
composing the machine, the one D is made fast to the foot A A, but the
other E is movable upon the solid base of the machine, by means of a
hinge at the point F. At I I is shown how the upper brass portion is
adjusted to the lower part made of iron; the two being secured to each
other by two stout screws. The comb, seen separately in _fig._ 527., is
made fast to the upper end of each jaw, by the three screws _n n n_.
_Fig._ 526. is a front view of the jaw mounted with its comb, to
illustrate its construction.

The lever K corresponds by the stout iron wire L, with a pedal pressed
by the needlewoman’s foot, whenever she wishes to separate the two jaws,
in order to insert between them the parallel edges of leather to be
sewed. The instant she lifts her foot, the two jaws join by the force of
the spring G, which pushes the movable jaw E against the stationary one
D. The spring is made fast to the frame of the vice by the screw H.

After putting the double edge to be sewed in its place, the woman passes
her needle successively through all the teeth of the comb, and is sure
of making a regular seam in every direction, provided she is careful to
make the needle graze along the bottom of the notches. As soon as this
piece is sewed, she presses down the pedal with her toes, whereby the
jaws start asunder, allowing her to introduce a new seam; and so in
quick succession.

The comb may have any desired shape, straight or curved; and the teeth
may be larger or smaller, according to the kind of work to be done. With
this view, the combs might be changed as occasion requires; but it is
more economical to have sets of vices ready mounted with combs of every
requisite size and form.


GLUCINA (_Glucine_, Fr.; _Berryllerde_, Germ.), is one of the primitive
earths, originally discovered by Vauquelin, in the beryl and emerald.
It may be extracted from either of these minerals, by treating their
powder successively with potash, with water, and with muriatic acid. The
solution by the latter, being evaporated to dryness, is to be digested
with water, and filtered. On pouring carbonate of ammonia in excess into
the liquid, we form soluble muriate of ammonia, with insoluble
carbonates of lime, chrome, and iron, as also carbonate of glucina,
which may be dissolved out from the rest by an excess of carbonate of
ammonia. When the liquid is filtered anew, the glucina passes through,
and may be precipitated in the state of a carbonate by boiling the
liquid, which expels the excess of ammonia. By washing, drying, and
calcining the carbonate, pure glucina is obtained. It is a white insipid
powder, infusible in the heat of a smith’s forge, insoluble in water,
but soluble in caustic potash and soda; as also, especially when it is a
hydrate, in carbonate of ammonia. It has a metallic base called
glucinum, of which 100 parts combine with 45·252 of oxygen to form the
earth. It is too rare to be susceptible of application in manufactures.


GLUE; (_Colle forte_, Fr.; _Leim_, _Tischlerleim_, Germ.) is the
chemical substance gelatine in a dry state. The preparation and
preservation of the skin and other animal matters employed in the
manufacture of glue, constitute a peculiar branch of industry. Those who
exercise it should study to prevent the fermentation of the substances,
and to diminish the cost of carriage by depriving them of as much water
as can conveniently be done. They may then be put in preparation by
macerating them in milk of lime, renewed three or four times in the
course of a fortnight or three weeks. This process is performed in large
tanks of masonry. They are next taken out with all the adhering lime,
and laid in a layer, 2 or 3 inches thick, to drain and dry, upon a
sloping pavement, where they are turned over by prongs, two or three
times a day. The action of the lime dissolves the blood and certain soft
parts, attacks the epidermis, and disposes the gelatinous matter to
dissolve more readily. When the cleansed matters are dried, they may be
packed in sacks or hogsheads, and transported to the glue manufactory at
any distance. The principal substances of which glue is made are the
parings of ox and other thick hides, which form the strongest article;
the refuse of the leather dresser; both afford from 45 to 55 per cent.
of glue. The tendons, and many other offals of slaughter houses, also
afford materials, though of an inferior quality, for the purpose. The
refuse of tanneries, such as the ears of oxen, calves, sheep, &c., are
better articles; but parings of parchment, old gloves, and, in fact,
animal skin, in every form, uncombined with tannin, may be made into
glue.

The manufacturer who receives these materials, is generally careful to
ensure their purification by subjecting them to a weak lime steep, and
rinsing them by exposure in baskets to a stream of water. They are
lastly drained upon a sloping surface, as above described, and well
turned over till the quicklime gets mild by absorption of carbonic acid;
for, in its caustic state, it would damage the glue at the heat of
boiling water. It is not necessary, however, to dry them before they are
put into the boiler, because they dissolve faster in their soft and
tumefied state.

The boiler is made of copper, rather shallow in proportion to its area,
with a uniform flat bottom, equably exposed all over to the flame of the
fire. Above the true bottom there is a false one of copper or iron,
pierced with holes, and standing upon feet 3 or 4 inches high; which
serves to sustain the animal matters, and prevent them from being
injured by the fire. The copper being filled to two thirds of its height
with soft water, is then heaped up with the bulky animal substances, so
high as to surmount its brim. But soon after the ebullition begins they
sink down, and, in a few hours, get entirely immersed in the liquid.
They should be stirred about from time to time, and well pressed down
towards the false bottom, while a steady but gentle boil is maintained.

The solution must be drawn off in successive portions; a method which
fractions the products, or subdivides them into articles of various
value, gradually decreasing from the first portion drawn off to the
last. It has been ascertained by careful experiments that gelatine gets
altered over the fire very soon after it is dissolved, and it ought
therefore to be drawn off whenever it is sufficiently fluid and strong
for forming a clear gelatinous mass on cooling, capable of being cut
into moderately firm slices by the wire. This point is commonly
determined by filling half an egg-shell with the liquor, and exposing it
to the air to cool. The jelly ought to get very consistent in the course
of a few minutes; if not so, the boiling must be persisted in a little
longer. When this term is attained, the fire is smothered up, and the
contents of the boiler are left to settle for a quarter of an hour. The
stop-cock being partially turned, all the thin gelatinous liquor is run
off into a deep boiler, immersed in a warm-water bath, so that it may
continue hot and fluid for several hours. At the end of this time, the
supernatant clear liquid is to be drawn off into congealing boxes, as
will be presently explained.

The grounds, or undissolved matters in the boiler, are to be again
supplied with a quantity of boiling water from an adjoining copper, and
are to be once more subjected to the action of the fire, till the
contents assume the appearance of dissolved jelly, and afford a fresh
quantity of strong glue liquor, by the stop-cock. The grounds should be
subjected a third time to this operation, after which they may be put
into a bag, and squeezed in a press to leave nothing unextracted. The
latter solutions are usually too weak to form glue directly, but they
may be strengthened by boiling with a portion of fresh skin-parings.

[Illustration: 528]

_Fig._ 528. represents a convenient apparatus for the boiling of skins
into glue, in which there are three coppers upon three different levels;
the uppermost being acted upon by the waste heat of the chimney,
provides warm water in the most economical way; the second contains the
crude materials, with water for dissolving them; and the third receives
the solution to be settled. The last vessel is double, with water
contained between the outer and inner one; and discharges its contents
by a stop-cock into buckets for filling the gelatinizing wooden boxes.
The last made solution has about one five hundredth part of alum in
powder usually added to it, with proper agitation, after which it is
left to settle for several hours.

The three successive boils furnish three different qualities of glue.

Flanders or Dutch glue, long much esteemed on the Continent, was made in
the manner above described, but at two boils, from animal offals well
washed and soaked, so as to need less boiling. The liquor being drawn
off thinner, was therefore less coloured, and being made into thinner
plates was very transparent. The above two boils gave two qualities of
glue.

By the English practice, the whole of the animal matter is brought into
solution at once, and the liquor being drawn off, hot water is poured on
the residuum, and made to boil on it for some time, when the liquor thus
obtained is merely used instead of water upon a fresh quantity of glue
materials. The first drawn off liquor is kept hot in a settling copper
for five hours, and then the clear solution is drawn off into the boxes.

These boxes are made of deal, of a square form, but a little narrower at
bottom than at top. When very regular cakes of glue are wished for,
cross grooves of the desired square form are cut in the bottom of the
box. The liquid glue is poured into the boxes placed very level, through
funnels furnished with filter cloths, till it stands at the brim of
each. The apartment in which this is done ought to be as cool and dry as
possible, to favour the solidification of the glue, and should be
floored with stone flags kept very clean, so that if any glue run
through the seams, it may be recovered. At the end of 12 or 18 hours, or
usually in the morning if the boxes have been filled overnight, the glue
is sufficiently firm for the nets, and they are at this time removed to
an upper story, mounted with ventilating windows to admit the air from
all quarters. Here the boxes are inverted upon a moistened table, so
that the gelatinous cake thus turned out will not adhere to its surface;
usually the moist blade of a long knife is insinuated round the sides of
the boxes beforehand, to loosen the glue. The mass is first divided into
horizontal layers by a brass wire stretched in a frame, like that of a
bow-saw, and guided by rulers which are placed at distances
corresponding to the desired thickness of the cake of glue. The lines
formed by the grooves in the bottom of the box define the superficial
area of each cake, where it is to be cut with a moist knife. The
gelatinous layers thus formed, must be dexterously lifted, and
immediately laid upon nets stretched in wooden frames, till each frame
be filled. These frames are set over each other at distances of about
three inches, being supported by small wooden pegs, stuck into mortise
holes in an upright, fixed round the room; so that the air may have
perfectly free access on every side. The cakes must moreover be turned
upside down upon the nets twice or thrice every day, which is readily
managed, as each frame may be slid out like a drawer, upon the pegs at
its two sides.

The drying of the glue is the most precarious part of the manufacture.
The least disturbance of the weather may injure the glue during the two
or three first days of its exposure; should the temperature of the air
rise considerably, the gelatine may turn so soft as to become unshapely,
and even to run through the meshes upon the pieces below, or it may get
attached to the strings and surround them, so as not to be separable
without plunging the net into boiling water. If frost supervene, the
water may freeze and form numerous cracks in the cakes. Such pieces must
be immediately re-melted and re-formed. A slight fog even produces upon
glue newly exposed a serious deterioration; the damp condensed upon its
surface occasioning a general mouldiness. A thunderstorm sometimes
destroys the coagulating power in the whole laminæ at once; or causes
the glue to _turn_ on the nets, in the language of the manufacturer. A
wind too dry or too hot may cause it to dry so quickly, as to prevent it
from contracting to its proper size without numerous cracks and
fissures. In this predicament, the closing of all the flaps of the
windows is the only means of abating the mischief. On these accounts it
is of importance to select the most temperate season of the year, such
as spring and autumn, for the glue manufacture.

After the glue is dried upon the nets it may still preserve too much
flexibility, or softness at least, to be saleable; in which case it must
be dried in a stove by artificial heat. This aid is peculiarly requisite
in a humid climate, like that of Great Britain.

When sufficiently dry it next receives a gloss, by being dipped cake by
cake in hot water, and then rubbed with a brush also moistened in hot
water; after which the glue is arranged upon a hurdle, and transferred
to the stove room, if the weather be not sufficiently hot. One day of
proper drought will make it ready for being packed up in casks.

The pale-coloured, hard and solid, article, possessing a brilliant
fracture, which is made from the parings of ox-hides by the first
process, is the best and most cohesive, and is most suitable for
joiners, cabinet-makers, painters, &c. But many workmen are influenced
by such ignorant prejudices, that they still prefer a dark-coloured
article, with somewhat of a fetid odour, indicative of its impurity and
bad preparation, the result of bad materials and too long exposure to
the boiling heat.

There is a good deal of glue made in France from bones, freed from the
phosphate of lime by muriatic acid. This is a poor article, possessing
little cohesive force. It dissolves almost entirely in cold water, which
is the best criterion of its imperfection. Glue should merely soften in
cold water, and the more considerably it swells, the better generally
speaking, it is.

Some manufacturers prefer a brass to a copper pan for boiling glue, and
insist much on skimming it as it boils; but the apparatus I have
represented renders skimming of little consequence. For use, glue should
be broken into small pieces, put along with some water into a vessel,
allowed to soak for some hours, and subjected to the heat of a
boiling-water bath, but not boiled itself. The surrounding hot water
keeps it long in a fit state for joiners, cabinet-makers, &c.

Water containing only one hundredth part of good glue, forms a tremulous
solid. When the solution, however, is heated and cooled several times,
it loses the property of gelatinizing, even though it be enclosed in a
vessel hermetically sealed. Isinglass or fish-glue undergoes the same
change. Common glue is not soluble in alcohol, but is precipitated in a
white, coherent, elastic mass, when its watery solution is treated with
that fluid. By transmitting chlorine gas through a warm solution of
glue, a combination is very readily effected, and a viscid mass is
obtained like that thrown down by alcohol. A little chlorine suffices to
precipitate the whole of the glue. Concentrated sulphuric acid makes
glue undergo remarkable changes; during which are produced, sugar of
gelatine, leucine, an animal matter, &c. Nitric acid, with the aid of
heat, converts glue into malic acid, oxalic acid, a fat analogous to
suet, and into tannin; so that, in this way, one piece of skin may be
made to tan another. When the mixture of glue and nitric acid is much
evaporated, a detonation at last takes place. Strong acetic acid renders
glue first soft and transparent, and then dissolves it. Though the
solution does not gelatinize, it preserves the property of gluing
surfaces together when it dries. Liquid glue dissolves a considerable
quantity of lime, and also of the phosphate of lime recently
precipitated. Accordingly glue is sometimes contaminated with that salt.
Tannin both natural and artificial combines with glue; and with such
effect, that one part of glue dissolved in 5000 parts of water affords a
sensible precipitate with the infusion of nutgalls. Tannin unites with
glue in several proportions, which are to each other as the numbers 1,
1-1/2, and 2; one compound consists of 100 glue and 89 tannin; another
of 100 glue and 60 tannin; and a third of 100 glue and 120 tannin. These
two substances cannot be afterwards separated from each other by any
known chemical process.

Glue may be freed from the foreign animal matters generally present in
it, by softening it in cold water, washing it with the same several
times till it no longer gives out any colour, then bruising it with the
hand, and suspending it in a linen bag beneath the surface of a large
quantity of water at 60° F. In this case, the water loaded with the
soluble impurities of the glue gradually sinks to the bottom of the
vessel, while the pure glue remains in the bag surrounded with water. If
this softened glue be heated to 92° without adding water, it will
liquefy; and if we heat it to 122°, and filter it, some albuminous and
other impurities will remain on the filter, while a colourless solution
of glue will pass through.

Experiments have not yet explained how gelatine is formed from skin by
ebullition. It is a change somewhat analogous to that of starch into gum
and sugar, and takes place without any appreciable disengagement of gas,
and even in close vessels. Gelatine, says Berzelius, does not exist in
the living body, but several animal tissues, such as skin, cartilages,
hartshorn, tendons, the serous membranes, and bones, are susceptible of
being converted into it.


GLUTEN; (_Colle Vegetale_, Fr.; _Kleber_, Germ.) was first extracted by
Beccaria from wheat flour, and was long regarded as a proximate
principle of plants, till Einhof, Taddei, and Berzelius, succeeded in
showing that it may be resolved by means of alcohol into three different
substances, one of which resembles closely animal albumine, and has been
called _Zymome_, or vegetable albumine; another has been called
_Gliadine_; and a third _Mucine_. The mode of separating gluten from the
other constituents of wheat flour, has been described towards the end of
the article BREAD.

Gluten when dried in the air or a stove, diminishes greatly in size,
becomes hard, brittle, glistening, and of a deep yellow colour. It is
insoluble in ether, in fat and essential oils, and nearly so in water.
Alcohol and acetic acid cause gluten to swell and make a sort of milky
solution. Dilute acids and alkaline lyes dissolve gluten. Its ultimate
constituents are not determined, but azote is one of them, and
accordingly when moist gluten is left to ferment, it exhales the smell
of old cheese.


GLYCERINE, is a sweet substance which may be extracted from fatty
substances. If we take equal parts of olive oil, and finely-ground
litharge, put them into a basin with a little water, set this on a sand
bath moderately heated, and stir the mixture constantly, with the
occasional addition of hot water to replace what is lost by evaporation,
we shall obtain in a short time, a soap or plaster of lead. After having
added more water to this, we remove the vessel from the fire, decant the
liquor, filter it, pass sulphuretted hydrogen through it to separate the
lead, then filter afresh, and concentrate the liquor as much as is
possible without burning upon the sand bath. What remains must be
finally evaporated within the receiver of the air-pump. Glycerine thus
prepared is a transparent liquid, without colour or smell, and of a
syrupy consistence. It has a very sweet taste. Its specific gravity is
1·27 at the temperature of 60°. When thrown upon burning coals, it takes
fire and burns like an oil. Water combines with it in almost all
proportions; alcohol dissolves it readily; nitric acid converts it into
oxalic acid; and according to Vogel, sulphuric acid transforms it into
sugar, in the same way as it does starch. Ferment or yeast does not
affect it in any degree.

Its constituents are, carbon 40; hydrogen 9; oxygen 51; in 100.


GNEISS, is the name of one of the great mountain formations, being
reckoned the oldest of the stratified rocks. It is composed of the same
substances as granite, viz. quartz, mica, and felspar. In gneiss however
they are not in granular crystals, but in scales, so as to give the mass
a slaty structure. It abounds in metallic treasures.


GOLD. (Eng. and Germ.; _Or_, Fr.) This metal is distinguished by its
splendid yellow colour; its great density = 19·3, compared to water 1·0;
its fusibility at the 32d degree of Wedgewood’s pyrometer; its
pre-eminent ductility and malleability, whence it can be beat into
leaves only one 282,000th of an inch thick; and its insolubility in any
acid menstruum, except the mixture of muriatic and nitric acids, styled
by the alchemists _aqua regia_, because gold was deemed by them to be
the king of metals.

Gold is found only in the metallic state, sometimes crystallized in the
cube, and its derivative forms. It occurs also in threads of various
size, twisted and interlaced into a chain of minute octahedral crystals;
as also in spangles or roundish grains, which when of a certain
magnitude are called _pepitas_. The small grains are not fragments
broken from a greater mass; but they shew by their flattened ovoid
shape, and their rounded outline, that this is their original state. The
spec. grav. of native gold varies from 13·3 to 17·7. Humboldt states
that the largest _pepita_ known was one found in Peru, weighing about 12
kilogrammes (26-1/2 lbs. avoird.); but masses have been quoted in the
province of Quito which weighed nearly four times as much.

Another ore of gold is the alloy with silver, or argental gold, the
electrum of Pliny, so called from its amber shade. It seems to be a
definite compound, containing in 100 parts, 64 of gold, and 36 of
silver.

The mineral formations in which this metal occurs, are the crystalline
primitive rocks, the compact transition rocks, the trachytic and trap
rocks, and alluvial grounds.

It never predominates to such a degree as to constitute veins by itself.
It is either disseminated, and as it were impasted in stony masses, or
spread out in thin plates or grains on their surface, or, lastly,
implanted in their cavities, under the shape of filaments or
crystallized twigs. The minerals composing the veins are either quartz,
calc-spar, or sulphate of baryta. The ores that accompany the gold in
these veins are chiefly iron pyrites, copper pyrites, galena, blende,
and mispickel (arsenical pyrites.)

In the ores called auriferous pyrites, this metal occurs either in a
visible or invisible form, and though invisible in the fresh pyrites,
becomes visible by its decomposition; as the hydrated oxide of iron
allows the native gold particles to shine forth on their reddish-brown
ground, even when the precious metal may constitute only the five
millionth part of its weight, as at Rammelsberg in the Hartz. In that
state it has been extracted with profit; most frequently by amalgamation
with mercury, proving that the gold was in the native state, and not in
that of a sulphuret.

Gold exists among the primitive strata, disseminated in small grains,
spangles, and crystals. Brazil affords a remarkable example of this
species of gold mine. Beds of granular quartz, or micaceous specular
iron, in the Sierra of Cocäes, 12 leagues beyond Villa Rica, which form
a portion of a mica-slate district, include a great quantity of native
gold in spangles, which in this ferruginous rock replace mica.

Gold has never been observed in any secondary formation, but pretty
abundantly in its true and primary locality, among the trap rocks of
igneous origin; implanted on the sides of the fissures, or disseminated
in the veins.

The auriferous ores of Hungary and Transylvania, composed of tellurium,
silver pyrites or sulphuret of silver, and native gold, lie in masses or
powerful veins in a rock of trachyte or in a decomposed felspar
subordinate to it. Such is the locality of the gold ore of Königsberg,
of Telkebanya, between Eperies and Tokay in Hungary, and probably that
of the gold ores of Kapnick, Felsobanya, &c., in Transylvania; an
arrangement nearly the same with what occurs in Equatorial America. The
auriferous veins of Guanaxuato, of Real del Monte, of Villalpando, are
similar to those of Schemnitz in Hungary, as to magnitude, relative
position, the nature of the ores they include, and of the rocks they
traverse. These districts have impressed all mineralogists with the
evidences of the action of volcanic fire. Breislak and Hacquet have
described the gold mines of Transylvania as situated in the crater of an
ancient volcano. It is certain that the trachytes which form the
principal portions of the rocks including gold, are now almost
universally regarded as of igneous or volcanic origin.

It would seem, however, that the primary source of the gold is not in
these rocks, but rather in the sienites and greenstone prophyries below
them, which in Hungary and Transylvania are rich in great auriferous
deposits; for gold has never been found in the trachyte of the Euganean
mountains, of the mountains of the Vicentin, of those of Auvergne; all
of which are superposed upon granite rocks, barren in metal.

Finally, if it be true that the ancients worked mines of gold in the
island of Ischia, it would be another example, and a very remarkable
one, of the presence of this metal in trachytes of an origin evidently
volcanic.

Gold is, however, much more common in the alluvial grounds than among
the primitive and pyrogenous rocks just described. It is found
disseminated under the form of spangles, in the siliceous, argillaceous,
and ferruginous sands of certain plains and rivers, especially in their
re-entering angles, at the season of low water, and after storms and
temporary floods.

It has been supposed that the gold found in the beds of rivers had been
torn out by the waters from the veins and primitive rocks, which they
traverse. Some have even searched, but in vain, at the source of
auriferous streams for the native bed of this precious metal. The gold
in them belongs, however, to the grounds washed by the waters as they
glide along. This opinion, suggested at first by Delius, and supported
by Deborn, Guettard, Robitant, Balbo, &c., is founded upon just
observations. 1. The soil of these plains contains frequently, at a
certain depth, and in several spots, spangles of gold, separable by
washing. 2. The beds of the auriferous rivers and streamlets contain
more gold after storms of rain upon the plains than in any other
circumstances. 3. It happens almost always that gold is found among the
sands of rivers only in a very circumscribed space; on ascending these
rivers their sands cease to afford gold; though did this metal come from
the rocks above, it should be found more abundantly near the source of
the rivers. Thus it is known that the Orco contains no gold except from
Pont to its junction with the Po. The Ticino affords gold only below the
Lago Maggiore, and consequently far from the primitive mountains, after
traversing a lake, where its course is slackened, and into which
whatsoever it carried down from these mountains must have been
deposited. The Rhine gives more gold near Strasburg than near Basle,
though the latter be much closer to the mountains. The sands of the
Danube do not contain a grain of gold, while this river runs in a
mountainous region; that is, from the frontiers of the bishoprick of
Passau to Efferding; but its sands become auriferous in the plains
below. The same thing is true of the Ems; the sands of the upper portion
of this river, as it flows among the mountains of Styria, include no
gold; but from its entrance into the plain at Steyer, till its
embouchure in the Danube, its sands become auriferous, and are even rich
enough to be washed with profit.

The greater part of the auriferous sands, in Europe, Asia, Africa, and
America, are black or red, and consequently ferruginous; a remarkable
circumstance in the geological position of alluvial gold. M. Napione
supposes that the gold of these ferruginous grounds is due to the
decomposition of auriferous pyrites. The auriferous sand occurring in
Hungary almost always in the neighbourhood of the beds of _lignites_,
and the petrified wood covered with gold grains, found buried at a depth
of 55 yards in clay, in the mine of Vorospatak near Abrabanya in
Transylvania, might lead us to presume that the epoch of the formation
of the auriferous alluvia is not remote from that of the lignites. The
same association of gold ore and fossil wood occurs in South America, at
Moco. Near the village of Lloro, have been discovered at a depth of 20
feet, large trunks of petrified trees, surrounded with fragments of trap
rocks interspersed with spangles of gold and platinum. But the alluvial
soil affords likewise all the characters of the basaltic rocks; thus in
France, the Cèze and the Gardon, auriferous rivers, where they afford
most gold, flow over ground apparently derived from the destruction of
the trap rocks, which occur _in situ_ higher up the country. This fact
had struck Reaumur, and this celebrated observer had remarked that the
sand which more immediately accompanies the gold spangles in most
rivers, and particularly in the Rhone and the Rhine, is composed, like
that of Ceylon and Expailly, of black protoxide of iron and small grains
of rubies, corindon, hyacinth, &c. Titanium has been observed more
recently. It has, lastly, been remarked that the gold of alluvial
formations is purer than that extracted from rocks.

_Principal Gold Mines._

Spain anciently possessed mines of gold in regular veins, especially in
the province of Asturias; but the richness of the American mines has
made them be neglected. The Tagus, and some other streams of that
country, were said to roll over golden sands. France contains no
workable gold mines; but it presents in several of its rivers auriferous
sands. There are some gold mines in Piedmont; particularly the veins of
auriferous pyrites of Macugnagna, at the foot of Monte Rosa, lying in a
mountain of gneiss; and although they do not contain 10 or 11 grains of
gold in a hundred weight, they have long defrayed the expense of working
them. On the southern slope of the Pennine Alps, from the Simplon and
Monte Rosa to the valley of Aoste, several auriferous districts and
rivers occur. Such are the torrent Evenson, which has afforded much gold
by washing; the Orco, in its passage from the Pont to the Po; the
reddish grounds over which this little river runs for several miles, and
the hills in the neighbourhood of Chivasso, contain gold spangles in
considerable quantity.

In the county of Wicklow, in Ireland, a quartzose and ferruginous sand
was discovered not long ago, containing many particles of gold, with
_pepitas_ or solid pieces, one of which weighed 22 ounces. No less than
1000 ounces of gold were collected.

There are auriferous sands in some rivers of Switzerland, as the Reuss
and the Aar. In Germany no mine of gold is worked, except in the
territory of Salzburg, amid the chain of mountains which separates the
Tyrol and Carinthia.

The mines of Hungary and Transylvania are the only gold mines of any
importance in Europe; they are remarkable for their position, the
peculiar metals that accompany them, and their product, estimated at
about 1430 pounds avoird. annually. The principal ones are in Hungary.
1. Those of Konigsberg. The native gold is disseminated in ores of
sulphuret of silver, which occur in small masses and in veins in a
decomposing felspar rock, amid a conglomerate of pumice, constituting a
portion of the trachytic formation. 2. Those of Borson, Schemnitz. And,
3 of Felsobanya; ores also of auriferous sulphuret of silver, occur in
veins of sienite and greenstone porphyry. 4. Those of Telkebanya, to the
south of Kaschau, are in a deposit of auriferous pyrites amid trap rocks
of the most recent formation.

In Transylvania the gold mines occur in veins often of great magnitude,
6, 8, and sometimes 40 yards thick. These veins have no side plates or
wall stones, but abut without intermediate gangues at the primitive
rock. They consist of carious quartz, ferriferous limestone, heavy spar,
fluor spar, and sulphuret of silver. The mine of Kapnik deserves notice,
where the gold is associated with orpiment, and that of Vorospatak in
granite rocks; those of Offenbanya, Zalatna, and Nagy-Ag, where it is
associated with Tellurium. The last is in a sienitic rock on the limits
of the trachyte.

In Sweden, the mine of Edelfors in Smoland may be mentioned, where the
gold occurs native and in auriferous pyrites; the veins are a brown
quartz, in a mountain of foliated hornstone.

In Siberia, native gold occurs in a hornstone at Schlangenberg or Zmeof,
and at Zmeino-garsk in the Altai mountains, accompanied with many other
ores.

The gold mine of Berezof in the Oural mountains, has been long known,
consisting of _partially decomposed auriferous pyrites_, disseminated in
a vein of greasy quartz. About 1820, a very rich deposit of native gold
was discovered upon the eastern side of the Oural mountains,
disseminated at some yards depth, in an argillaceous loam, and
accompanied with the _débris_ of rocks which usually compose the
auriferous alluvial soils, as greenstone, serpentine, protoxide of iron,
corundum, &c. The rivers of this district possess auriferous sands. The
annual product of the gold mines of Siberia is 3740 pounds avoirdupois.

In Asia, and especially in its southern districts, there are many mines,
streams, rivers, and wastes, which contain this metal. The Pactolus, a
small river of Lydia, rolled over such golden sands, that it was
supposed to constitute the origin of the wealth of Crœsus. But these
deposits are now poor and forgotten. Japan, Formosa, Ceylon, Java,
Sumatra, Borneo, the Philippines, and some other islands of the Indian
Archipelago, are supposed to be very rich in gold mines. Those of Borneo
are worked by the Chinese in an alluvial soil on the western coast, at
the foot of a chain of volcanic mountains.

Little or no gold comes into Europe from Asia, because its servile
inhabitants place their fortune in treasure, and love to hoard up that
precious metal.

Numerous gold mines occur on the two slopes of the chain of the Cailas
mountains in the Oundès, a province of Little Thibet. The gold lies in
quartz veins which traverse a very crumbling reddish granite.

Africa was, with Spain, the source of the greater portion of the gold
possessed by the antients. The gold which Africa still brings into the
market in abundance is always in dust, showing that the metal is
obtained by washing the alluvial soils. None of it is collected in the
north of that continent; three or four districts only are remarkable for
the quantity of gold they produce.

The first mines are those of Kordofan, between Darfour and Abyssinia.
The negroes transport the gold in quills of the ostrich or vulture.
These mines seem to have been known to the antients, who considered
Ethiopia to abound in gold. Herodotus relates that the king of that
country exhibited to the ambassadors of Cambyses, all their prisoners
bound with golden chains.

The second and chief exploitation of gold dust is to the south of the
great desert of Zaara, in the western part of Africa, from the mouth of
the Senegal to the Cape of Palms. The gold occurs in spangles, chiefly
near the surface of the earth, in the bed of rivulets, and always in a
ferruginous earth. In some places the negroes dig wells in the soil to a
depth of about 40 feet, unsupported by any props. They do not follow any
vein; nor do they construct a gallery. By repeated washings they
separate the gold from the earthy matters.

The same district furnishes also the greater part of what is carried to
Morocco, Fez, and Algiers, by the caravans which go from Timbuctoo on
the Niger, across the great desert of Zaara. The gold which arrives by
Sennaar at Cairo and Alexandria, comes from the same quarter. From Mungo
Park’s description, it appears that the gold spangles are found usually
in a ferruginous small gravel, buried under rolled pebbles.

The third spot in Africa where gold is collected, is on the south-east
coast, between the twenty-fifth and the twenty-second degree of south
latitude, opposite to Madagascar, in the country of Sofala. Some persons
think that this was the kingdom of Ophir, whence Solomon obtained his
gold.

In modern times, the richest gold mines are found in America, from which
there is exported annually, 3700 or 4000 pounds avoirdupois of this
metal. It occurs there principally in spangles among the alluvial
earths, and in the beds of rivers; more rarely in veins.

There is little gold in the northern part of America. The United States
have hitherto produced but a slight quantity of alluvial gold, collected
in the gravel-pits of the creeks of Rockhole, district of Lebanon, in
North Carolina. In 1810, a mass was found there, weighing 28 pounds.
This district has furnished the mint of the United States with about 100
lbs. avoirdupois of gold.

South America, especially Brazil, Choco, and Chili, are the regions
which furnish most gold.

The gold of Mexico is in a great measure contained in the argentiferous
veins, so numerous in that country, whose principal localities are
mentioned under the article SILVER. The silver of the argentiferous ores
of Guanaxato, contains one 360th of its weight of gold; the annual
product of the mines being valued at from 2640 to 3300 pounds
avoirdupois.

Oaxaco contains the only auriferous veins exploited as gold mines in
Mexico; they traverse rocks of gneiss and mica slate.

All the rivers of the province of Caracas, to ten degrees north of the
line, flow over golden sands.

Peru is not rich in gold ores. In the provinces of Huailas and Pataz,
this metal is mined in veins of greasy quartz, variegated with red
ferruginous spots, which traverse primitive rocks. The mines called
_pacos de oro_, consist of ores of iron and copper oxides, containing a
great quantity of gold.

All the gold furnished by New Grenada (New Colombia), is the product of
washings, established in alluvial grounds. The gold exists in spangles
and in grains, disseminated among fragments of greenstone and porphyry.
At Choco, along with the gold and platinum, hyacinths, zircons, and
titanium occur. There has been found, as already stated, in the
auriferous localities, large trunks of petrified trees. The gold of
Antioquia is 20 carats fine, that of Choco 21, and the largest lump or
_pepita_ of gold weighed about 27-1/2 pounds avoirdupois. The gold of
Chili also occurs in alluvial formations.

Brazil furnishes the greatest part of the gold now brought into the
market. Yet there is not in this country any gold mine properly so
called; for the veins containing the metal are seldom worked.

It is in the sands of the Mandi, a branch of the Rio-Dolce, at
Catapreta, that the auriferous ferruginous sands were first discovered
in 1682. Since then, they have been found almost everywhere at the foot
of the immense chain of mountains, which runs nearly parallel with the
coast, from the 5th degree south to the 30th. It is particularly near
Villa Rica, in the environs of the village Cocäes, that the numerous
washings for gold are established. The _pepitas_ occur in different
forms, often adhering to micaceous specular iron. But in the province of
Minas Geräes, the gold occurs also in veins, in beds, and in grains,
disseminated among the alluvial loams. It has been estimated in annual
product, by several authors, at about 2800 pounds avoirdupois of fine
metal; worth nearly a million sterling.

We thus see that almost all the gold brought into the market, comes from
alluvial lands, and is extracted by washing.

The gold coin of the ancients was made chiefly out of alluvial gold, for
in these early times the metallurgic arts were not sufficiently advanced
to enable them to purify it. The gold dust from Bambouk in Africa, is of
22-1/4 carats fine, and some from Morocco is even 23.

The gold of Giron, in New Grenada, is of 23-3/4 carats; being the purest
from America. “For those who traffick in gold,” says Humboldt, “it is
sufficient to learn the place where the metal has been collected, to
know its title.”

_Metallurgic treatment of gold._--The gold found in the sands of rivers,
or in auriferous soils, needs not be subjected to any metallurgic
process, properly speaking. The Orpaillers, separate it from the sands,
by washing them first upon inclined tables, sometimes covered with a
cloth, and then by hand in wooden bowls of a particular form.
Amalgamation is employed to carry off from the sand, the minuter
particles of gold they may contain. The people called Bohemians, Cigans,
or Tehinganes, who wash the auriferous sands in Hungary, employ a plank
with 24 transverse grooves cut in its surface. They hold this plank in
an inclined position, and put the sand to be washed in the first groove;
they then throw water on it, when the gold mixed with a little sand
collects usually towards the lowest furrow. They remove this mixture
into a flat wooden basin, and by a peculiar sleight of hand, separate
the gold entirely from the sand. The richest of the auriferous ores
consist of the native gold quite visible, disseminated in a gangue, but
the veins are seldom continuous for any length. The other ores are
auriferous metallic sulphurets, such as sulphurets of copper, silver,
arsenic, &c., and, particularly iron.

The stony ores are first ground in the stamping mill, and then washed in
hand-basins, or on wooden tables.

The auriferous sulphurets are much more common, but much poorer than the
former ores; some contain only one 200,000th part of gold, and yet they
may be worked with advantage, when treated with skill and economy.

The gold of these ores is separated by two different processes; namely,
by fusion and amalgamation.

The auriferous metallic sulphurets are first roasted; then melted into
_mattes_, which are roasted anew; next fused with lead, whence an
auriferous lead is obtained, which may be refined by the process of
cupellation.

When the gold ores are very rich, they are melted directly with lead,
without preliminary calcination or fusion. These processes are however
little practised, because they are less economical and certain than
amalgamation, especially when the gold ores are very poor.

If these ores consist of copper pyrites, and if their treatment has been
pushed to the point of obtaining auriferous rose copper, or even black
copper including gold, the precious metal cannot be separated by the
process of liquation, because the gold having more affinity for copper
than for lead, can be but partially run off by the latter metal. For
these reasons the process of amalgamation is far preferable.

This process being the same for silver, I shall reserve its description
for this metal. The rich ores in which the native gold is apparent, and
merely disseminated in a stony gangue, are directly triturated with
quicksilver, without any preparatory operation. As to the poor ores, in
which the gold seems lost amid a great mass of iron, sulphuret of
copper, &c., they are subjected to a roasting before being amalgamated.
This process seems requisite to lay bare the gold enveloped in the
sulphurets. The quicksilver with which the ore is now ground, seizes the
whole of its gold, in however small quantity this metal may be present.

The gold procured by the refining process with lead, is free from copper
and lead, but it may contain iron, tin, or silver. It cannot be
separated from iron and tin without great difficulty, and expense, if
the proportion of gold be too small to admit of the employment of
muriatic acid.

By cupellation with lead, gold may be deprived of any antimony united
with it.

Tin gives gold a remarkable hardness and brittleness; a piece of gold,
exposed for some time over a bath of red hot tin, becomes brittle. The
same thing happens more readily over antimony, from the volatility of
this metal. A two thousandth part of antimony, bismuth, or lead,
destroys the ductility of gold. The tin may be got rid of by throwing
some corrosive sublimate or nitre into a crucible, containing the melted
alloy. By the first agent, perchloride of tin is volatilized; by the
second, _stannate_ of potash forms, which is carried off in the
resulting alkaline scoriæ.

Gold treated by the process of amalgamation, contains commonly nothing
but a little silver. The silver is dissolved out by nitric acid, which
leaves the gold untouched; but to make this _parting_ with success and
economy on the great scale, several precautions must be observed.

If the gold do not contain fully two thirds of its weight of silver,
this metal being thoroughly enveloped by the gold, is partially screened
from the action of the acid. Whenever, therefore, it is known by a trial
on a small scale, that the silver is much below this proportion, we must
bring the alloy of gold and silver to that standard by adding the
requisite quantity of the latter metal. This process is called
quartation.

This alloy is then granulated or laminated; and from twice to thrice its
weight of sulphuric or nitric acid is to be boiled upon it; and when it
is judged that the solution has been pushed as far as possible by this
first acid, it is decanted, and new acid is poured on. Lastly, after
having washed the gold, some sulphuric acid is to be boiled over it,
which carries off a two or three thousandth part of silver, which nitric
acid alone could not dissolve. Thus perfectly pure gold is obtained.

The silver held in solution by the sulphuric or nitric acid is
precipitated in the metallic state by copper, or in the state of
chloride by sea-salt. See PARTING.

Not only has the ratio between the value of gold and silver varied much
in different ages of the world; but the ratio between these metals and
the commodities they represent, has undergone variations, owing to the
circumstances in which their mines have been successively placed; since
they have always poured a greater quantity of the metals into the market
than has been absorbed by use. This quantity has greatly increased since
the discovery of America, a period of little more than 300 years. The
mines of that continent, rich, numerous, and easily worked, by
augmenting the mass of gold and silver, necessarily lessened the value
of these metals compared with that of the objects of commerce
represented by them, so that every thing else being equal, there is now
required for purchasing the same quantity of commodities, much more gold
or silver than was necessary in the reign of Henry VII., before the
discovery of America. This productiveness of the American mines has had
an influence on those of the ancient continent; many of whose silver and
gold mines have been abandoned, not because the veins or auriferous
sands are less rich than they were; but because their product no longer
represents the value of human labour, and of the goods to be furnished
in return for their exploitation.

In the 3d. vol. of the Mining Journal, p. 331., we have the following
statement as to the produce of the precious metals.--“In 40 years, from
1790 to 1830, Mexico produced 6,436,453_l._ worth of gold, and
139,818,032_l._ of silver. Chile, 2,768,488_l._ of gold, and
1,822,924_l._ of silver. Buenos Ayres, 4,024,895_l._ of gold, and
27,182,673_l._ of silver. Russia, 3,703,743_l._ of gold, and
1,502,981_l._ of silver. Total, 1880 millions sterling, or 47 millions
per annum.”

The following table shews what proportion the product of the mines of
America bears to that of the mines of the ancient continent.

_Table of the Quantities of Gold which may be considered as having been
brought into the European Market, every Year on an Average, from 1790 to
1802._

  +------------------------------+-----------+
  |           Continents.        |   Gold.   |
  +------------------------------+-----------+
  |       ANCIENT CONTINENT.     |lbs. Avoir.|
  |Asia:                         |           |
  |    Siberia                   |    3740   |
  |Africa                        |    3300   |
  |                              |           |
  |Europe:                       |           |
  |    Hungary                   |    1430   |
  |    Salzbourg                 |     165   |
  |    Austrian States          }|           |
  |    Hartz and Hessia         }|           |
  |    Saxony                   }|           |
  |    Norway                   }|     165   |
  |    Sweden                   }|           |
  |    France                   }|           |
  |    Spain, &c.               }|           |
  |                              +-----------+
  |Total of the Ancient Continent|    8800   |
  |                              +-----------+
  |          NEW CONTINENT.      |           |
  |North America                 |    2860   |
  |South America:                |           |
  |    Spanish dominions         |  22,000   |
  |    Brazil                    |  15,400   |
  |                              +-----------+
  |Total of the New Continent    |  40,260   |
  +------------------------------+-----------+

The mines of America have sent into Europe three and a half times more
gold, and twelve times more silver, than those of the ancient continent.
The total quantity of silver was to that of gold in the ratio of 55 to
1; a very different ratio from that which holds really in the value of
these two metals, which is in Europe as 1 to 15. This difference depends
upon several causes, which cannot be investigated here at length; but it
may be stated that gold, by its rarity and price, being much less
employed in the arts than silver, the demand for it is also much less;
and this cause is sufficient to lower its price much beneath what it
would have been, if it had followed the ratio of its quantity compared
to that of silver. Thus also bismuth, tin, &c., though much rarer than
silver, are, nevertheless, very inferior in price to it. Before the
discovery of America, the value of gold was not so distant from that of
silver, because since that era silver has been distributed in Europe in
a far greater proportion than gold. In Asia the proportion is now
actually only 1 to 11 or 12; the product of the gold mines in that
quarter, being not so much below that of the silver mines as in the rest
of the world.

The total annual production of Gold at present has been estimated as
follows.

  From the ancient Spanish colonies of America  10,400 kilogrammes
       Brazil                                      600
       Europe and Asiatic Russia                 6,200
       The Indian Archipelago                    4,700
       Africa                                   14,000?
                                                ------
                                                35,900 = 36 tons nearly

without taking into account the quantity of gold now extracted from
silver.

Gold has less affinity for oxygen than any other metal. When alone, it
cannot be oxidized by any degree of heat with contact of air, although
in combination with other oxidized bodies, it may pass into the state of
an oxide, and be even vitrified. The purple smoke into which gold leaf
is converted by an electric discharge is not an oxide, for it is equally
formed when the discharge is made through it in hydrogen gas. There are
two oxides of gold; the first or protoxide is a green powder, which may
be obtained by pouring, in the cold, a solution of potash into a
solution of the metallic chloride. It is not durable, but soon changes
in the menstruum into metallic gold, and peroxide. Its constituents are
96·13 metal, and 3·87 oxygen. The peroxide is best prepared by adding
magnesia to a solution of the metallic chloride; washing the precipitate
with water till this no longer takes a yellow tint from muriatic acid;
then digesting strong nitric acid upon the residuum, which removes the
magnesia, and leaves the peroxide in the form of a black or dark brown
powder, which seems to partake more of the properties of a metallic acid
than a base. It contains 10·77 per cent. of oxygen. For the curious
combination of gold and tin, called the PURPLE PRECIPITATE OF CASSIUS,
see this article, and PIGMENTS VITRIFIABLE.

_Gold beating._--This is the art of reducing gold to extremely thin
leaves, by beating with a hammer. The processes employed for this
purpose may be applied to other metals, as silver, platinum, and copper.
Under tin, zinc, &c., we shall mention such modifications of the
processes as these metals require to reduce them to thin leaves. The
Romans used to gild the ceilings and walls of their apartments; and
Pliny tells us, that from an ounce of gold forming a plate of 4 fingers
square, about 600 leaves of the same area were hammered. At the present
day, a piece of gold is extended so as to cover a space 651,590 times
greater than its primary surface when cast.

The gold employed in this art ought to be of the finest standard. Alloy
hardens gold, and renders it less malleable; so that the fraudulent
tradesman who should attempt to debase the gold, would expose himself to
much greater loss in the operations, than he could derive of profit from
the alloy.

Four principal operations constitute the art of gold beating. 1. The
casting of the gold ingots. 2. The hammering. 3. The lamination; and 4.,
the beating.

1. The gold is melted in a crucible along with a little borax. When it
has become liquid enough, it is poured out into the ingot-moulds
previously heated, and greased on the inside. The ingot is taken out and
annealed in hot ashes, which both soften it and free it from grease. The
moulds are made of cast iron, with a somewhat concave internal surface,
to compensate for the greater contraction of the central parts of the
metal in cooling than the edges. The ingots weigh about 2 ounces each,
and are 3/4 of an inch broad.

2. _The forging._--When the ingot is cold, the French gold-beaters
hammer it out on a mass of steel 4 inches long and 3 broad. The hammer
for this purpose is called the forging hammer. It weighs about 3 pounds,
with a head at one end and a wedge at the other, the head presenting a
square face of 1-1/2 inches. Its handle is 6 inches long. The workman
reduces the ingot to the thickness of 1/6 of an inch at most; and during
this Operation he anneals it whenever its substance becomes hard and apt
to crack. The English gold-beaters omit this process of hammering.

3. _The lamination._--The rollers employed for this purpose should be of
a most perfectly cylindrical figure, a polished surface, and so powerful
as not to bend or yield in the operation. The ultimate excellence of the
gold leaf depends very much on the precision with which the riband is
extended in the rolling press. The laminating machine represented under
the article MINT, is an excellent pattern for this purpose. The
gold-beater desires to have a riband of such thinness that a square inch
of it will weigh 6-1/2 grains. Frequent annealings are requisite during
the lamination.

4. _Beating._--The riband of gold being thus prepared uniform, the
gold-beater cuts it with shears into small squares of an inch each,
having previously divided it with compasses, so that the pieces may be
of as equal weight as possible. These squares are piled over each other
in parcels of 150, with a piece of fine calf-skin vellum interposed
between each, and about 20 extra vellums at the top and bottom. These
vellum leaves are about 4 inches square, on whose centre lie the gold
laminæ of an inch square. This packet is kept together by being thrust
into a case of strong parchment open at the ends, so as to form a belt
or band, whose open sides are covered in by a second case drawn over the
packet at right angles to the first. Thus the packet becomes
sufficiently compact to bear beating with a hammer of 15 or 16 pounds
weight, having a circular face nearly 4 inches diameter, and somewhat
convex, whereby it strikes the centre of the packet most forcibly, and
thus squeezes out the plates laterally.

The beating is performed on a very strong bench or stool framed to
receive a heavy block of marble, about 9 inches square on the surface,
enclosed upon every side by woodwork, except the front where a leather
apron is attached, which the workman lays before him to preserve any
fragments of gold that may fall out of the packet. The hammer is
short-handled, and is managed by the workman with one hand; who strikes
fairly on the middle of the packet, frequently turning it over to beat
both sides alike; a feat dexterously done in the interval of two
strokes, so as not to lose a blow. The packet is occasionally bent or
rolled between the hands, to loosen the leaves and secure the ready
extension of the gold; or it is taken to pieces to examine the gold, and
to shift the central leaves to the outside, and vice versa, that every
thing may be equalized. Whenever the gold plates have extended under
this treatment, to nearly the size of the vellum, they are removed from
the packet, and cut into four equal squares by a knife. They are thus
reduced to nearly the same size as at first, and are again made up into
packets and enclosed as before, with this difference, that skins
prepared from ox-gut are now interposed between each gold leaf, instead
of vellum. The second course of beating is performed with a smaller
hammer, about 10 pounds in weight, and is continued till the leaves are
extended to the size of the skins. During this period, the packet must
be often folded, to render the gold as loose as possible between the
membranes; otherwise the leaves are easily chafed and broken. They are
once more spread on a cushion, and subdivided into four square pieces by
means of two pieces of cane cut to very sharp edges, and fixed down
transversely on a board. This rectangular cross being applied on each
leaf, with slight pressure, divides it into four equal portions. These
are next made up into a third packet of convenient thickness, and
finally hammered out to the area of fine gold leaf, whose average size
is from 3 to 3-1/2 inches square. The leaves will now have obtained an
area 192 times greater than the plates before the hammering begun. As
these were originally an inch square, and 75 of them weighed an ounce (=
6-1/2 × 75 = 487-1/2), the surface of the finished leaves will be 192 ×
75 = 14,400 square inches, or 100 square feet per ounce troy. This is by
no means the ultimate degree of attenuation, for an ounce may be
hammered so as to cover 160 square feet; but the waste incident in this
case, from the number of broken leaves, and the increase and nicety of
the labour, make this an unprofitable refinement; while the gilder finds
such thin leaves to make less durable and satisfactory work.

The finished leaves of gold are put up in small books made of single
leaves of soft paper, rubbed over with red chalk to prevent adhesion
between them. Before putting the leaves in these books, however, they
are lifted one by one with a delicate pair of pincers out of the
finishing packet, and spread out on a leather cushion by blowing them
flat down. They are then cut to one size, by a sharp-edge square
moulding of cane, glued on a flat board. When this square-framed edge is
pressed upon the gold, it cuts it to the desired size and shape. Each
book commonly contains 25 gold leaves.

I shall now describe some peculiarities of the French practice of gold
beating. The workman cuts the laminated ribands of an inch broad into
portions an inch and a half long. These are called _quartiers_. He takes
24 of them, which he places exactly over each other, so as to form a
thickness of about an inch, the riband being 1/2 of a line, or 1/24 of
an inch thick; and he beats them together on the steel slab with the
round face (_panne_) of the hammer, so as to stretch them truly out into
the square form. He begins by extending the substance towards the edges,
thereafter advancing towards the middle; he then does as much on the
other side, and finally hammers the centre. By repeating this mode of
beating as often as necessary, he reduces at once all the _quartiers_
(squares) of the same packet, till none of them is thicker than a leaf
of gray paper, and of the size of a square of 2 inches each side.

When the _quartiers_ are brought to this state, the workman takes 56 of
them, which he piles over each other, and with which he forms the first
packet (_caucher_) in the manner already described; only two leaves of
vellum are interposed between each gold leaf. The empty leaves of vellum
at the top and bottom of the packet are called _emplures_. They are 4
inches square, as well as the parchment pieces.

The packet thus prepared forms a rectangular parallelopiped; it is
enclosed in two sheathes, composed each of several leaves of parchment
applied to each, and glued at the two sides, forming a bag open at
either end.

The block of black marble is a foot square at top, and 18 inches deep,
and is framed as above described. The hammer used for beating the first
packet is called the flat, or the enlarging hammer; its head is round,
about 5 inches in diameter, and very slightly convex. It is 6 inches
high, and tapers gradually from its head to the other extremity, which
gives it the form of a hexagonal truncated pyramid. It weighs 14 or 15
pounds.

The French gold-beaters employ besides this hammer, three others of the
same form; namely, 1. The _commencing hammer_, which weighs 6 or 7
pounds, has a head 4 inches in diameter, and is more convex than the
former. 2. The _spreading hammer_, (_marteau a chasser_); its head is
two inches diameter, more convex than the last, and weighs only 4 or 5
pounds. 3. _The finishing hammer_; it weighs 12 or 13 pounds, has a head
four inches diameter, and is the most convex of all.

The beating processes do not differ essentially from the English
described above. The vellum is rubbed over with fine calcined Paris
plaster, with a hare’s foot. The skin of the gold-beater is a pellicle
separated from the outer surface of ox-gut; but before being employed
for this purpose, it must undergo two preparations. 1. It is sweated, in
order to expel any grease it may contain. With this view, each piece of
membrane is placed between two leaves of white paper; several of these
pairs are piled over each other, and struck strongly with a hammer,
which drives the grease from the gut into the paper.

2. A body is given to the pieces of gut; that is, they are moistened
with an infusion of cinnamon, nutmeg, and other warm and aromatic
ingredients, in order to preserve them; an operation repeated after they
have been dried in the air. When the leaves of skin are dry, they are
put in a press, and are now ready for use. After the parchment, vellum,
and gut membrane have been a good deal hammered, they become unfit for
work, till they are restored to proper flexibility, by being placed leaf
by leaf, between leaves of white paper, moistened sometimes with
vinegar, at others with white wine. They are left in this predicament
for 3 or 4 hours, under compression of a plank loaded with weights. When
they have imbibed the proper humidity, they are put between leaves of
parchment 12 inches square, and beat in that situation for a whole day.
They are then rubbed over with fine calcined gypsum, as the vellum was
originally. The gut-skin is apt to contract damp in standing, and is
therefore dried before being used.

The average thickness of common gold leaf is 1/282000 of an inch.

_The art of Gilding._--This art consists in covering bodies with a thin
coat of gold; which may be done either by mechanical or chemical means.
The mechanical mode is the application of gold leaf or gold powder to
various surfaces, and their fixation by various means. Thus gold may be
applied to wood, plaster, pasteboard, leather; and to metals, such as
silver, copper, iron, tin, and bronze; so that gilding generally
speaking includes several arts, exercised by very different classes of
tradesmen.

I. _Mechanical Gilding._--Oil gilding is the first method under this
head, as oil is the fluid most generally used in the operation of this
mechanical art. The following process has been much extolled at Paris.

1. A coat of _impression_ is to be given first of all, namely, a coat of
white lead paint, made with drying linseed oil, containing very little
oil of turpentine.

2. Calcined ceruse is to be ground very well with unboiled linseed oil,
and tempered with essence of turpentine, in proportion as it is laid on.
Three or four coats of this _hard tint_ are to be applied evenly and
drily on the ornaments, and the parts which are to be most carefully
gilded.

3. The _Gold colour_ is then to be smoothly applied. This is merely the
dregs of the colours, ground and tempered with oil, which remain in the
little dish in which painters clean their brushes. This substance is
extremely rich and gluey; after being ground up, and passed through fine
linen cloth, it forms the ground for gold leaf.

4. When the gold colour is dry enough to catch hold of the leaf gold,
this is spread on the cushion, cut into pieces and carefully applied
with the pallet knife, pressed down with cotton, and in the small
ornaments with a fine brush.

5. If the gildings be for outside exposure, as balconies, gratings,
statues, &c., they must not be varnished, as simple oil gilding stands
better; for when it is varnished, a bright sun-beam acting after heavy
rain, gives the gilding a jagged appearance. When the objects are inside
ones, a coat of spirit varnish may be passed over the gold leaf, then a
glow from the gilder’s chafing dish may be given, and finally a coat of
oil varnish. The workman who causes the chafing dish to glide in front
of the varnished surface, must avoid stopping for an instant opposite
any point, otherwise he would cause the varnish to boil and blister.
This heat brings out the whole transparency of the varnish, and lustre
of the gold.

_Oil Gilding_ is employed with varnish polish, upon equipages,
mirror-frames, and other furniture. The following method is employed by
eminent gilders at Paris.

1. White lead, with half its weight of yellow ochre, and a little
litharge, are separately ground very fine; and the whole is then
tempered with linseed oil, thinned with essence of turpentine, and
applied in an evenly coat, called _impression_.

2. When this coat is quite dry, several coats of the hard tint are
given, even so many as 10 or 12, should the surface require it for
smoothing and filling up the pores. These coats are given daily, leaving
them to dry in the interval in a warm sunny exposure.

3. When the work is perfectly dry, it is first softened down with pumice
stone and water, afterwards with worsted cloth and very finely powdered
pumice, till the _hard tint_ give no reflection, and be smooth as glass.

4. With a camel’s hair brush, there must be given lightly and with a
gentle heat, from 4 to 5 coats at least, and even sometimes double that
number, of fine lac varnish.

5. When these are dry, the grounds of the pannels and the sculptures
must be first polished with shave-grass (_de la prèle_); and next with
putty of tin and tripoli, tempered with water, applied with woollen
cloth; by which the varnish is polished till it shines like a mirror.

6. The work thus polished is carried into a hot place, free from dust,
where it receives very lightly and smoothly, a thin coat of _gold
colour_, much softened down. This coat is passed over it with a clean
soft brush, and the thinner it is the better.

7. Whenever the gold colour is dry enough to take the gold, which is
known by laying the back of the hand on a corner of the frame work, the
gilding is begun and finished as usual.

8. The gold is smoothed off with a very soft brush, one of camel’s hair
for example, of three fingers’ breadth; after which it is left to dry
for several days.

9. It is then varnished with a spirit of wine varnish; which is treated
with the chafing dish as above described.

10. When this varnish is dry, two or three coats of copal, or oil
varnish are applied, at intervals of two days.

11. Finally, the pannels are polished with a worsted cloth, imbued with
tripoli and water, and lustre is given by friction with the palm of the
hand, previously softened with a little olive oil, taking care not to
rub off the gold.

In this country, _Burnished gilding_ is practised by first giving a
ground of size whiting, in several successive coats; next applying
gilding size; and then the gold leaf, which is burnished down with
agate, or a dog’s tooth.

_Gilding in distemper_ of the French, is the same as our burnished
gilding. Their process seems to be very elaborate, and the best consists
of 17 operations; each of them said to be essential.

1. _Encollage_, or the _Glue coat_. To a decoction of wormwood and
garlic in water, strained through a cloth, a little common salt, and
some vinegar are added. This composition, as being destructive of worms
in wood, is mixed with as much good glue; and the mixture is spread in a
hot state, with a brush of boar’s hair. When plaster or marble is to be
gilded, the salt must be left out of the above composition, as it is apt
to attract humidity in damp places, and to come out as a white powder on
the gilding. But the salt is indispensible for wood. The first glue
coating is made thinner than the second.

2. _White preparation._ This consists in covering the above surface,
with 8, 10, or 12 coats of Spanish white, mixed up with strong size,
each well worked on with the brush, and in some measure incorporated
with the preceding coat, to prevent their peeling off in scales.

3. _Stopping up_ the pores, with thick whiting and glue, and smoothing
the surface with dog-skin.

4. Polishing the surface with pumice-stone and very cold water.

5. _Reparation_; in which a skilful artist retouches the whole.

6. _Cleansing_; with a damp linen rag, and then a soft sponge.

7. _Préler._ This is rubbing with horse’s tail (_shave-grass_) the parts
to be yellowed, in order to make them softer.

8. _Yellowing._ With this view _yellow ochre_ is carefully ground in
water, and mixed with transparent colourless size. The thinner part of
this mixture is applied hot over the white surface with a fine brush,
which gives it a fine yellow hue.

9. _Ungraining_; consists in rubbing the whole work with shave-grass, to
remove any granular appearance.

10. _Coat of assiette; trencher coat._ This is the composition on which
the gold is to be laid. It is composed of Armenian bole, 1 pound;
bloodstone (hematite), 2 ounces; and as much galena; each separately
ground in water. The whole are then mixed together, and ground up with
about a spoonful of olive oil. The _assiette_ well made and applied
gives beauty to the gilding. The _assiette_ is tempered with a white
sheepskin glue, very clear and well strained. This mixture is heated and
applied in three successive coats, with a very fine long-haired brush.

11. _Rubbing_, with a piece of dry, clean linen cloth; except the parts
to be burnished, which are to receive other two coats of _assiette_
tempered with glue.

12. _Gilding._ The surface being damped with cold water, (iced in
summer) has then the gold leaf applied to it. The hollow grounds must
always be gilded before the prominent parts. Water is dexterously
applied by a soft brush, immediately behind the gold leaf, before laying
it down, which makes it lie smoother. Any excess of water is then
removed with a dry brush.

13. _Burnishing_, with bloodstone.

14. _Deadening._ This consists in passing a thin coat of glue slightly
warmed, over the parts that are not to be burnished.

15. _Mending_; that is moistening any broken points with a brush, and
applying bits of gold leaf to them.

16. The _vermeil_ coat. Vermeil is a liquid which gives lustre and fire
to the gold; and makes it resemble _or moulu_. It is composed as
follows: 2 ounces of annotto, 1 ounce of gamboge, 1 ounce of vermillion,
half an ounce of dragon’s blood, 2 ounces of salt of tartar, and 18
grains of saffron, are boiled in a litre (2 pints English) of water,
over a slow fire, till the liquid be reduced to a fourth. The whole is
then passed through a silk or muslin sieve. A little of this is made to
glide lightly over the gold, with a very soft brush.

17. _Repassage_; is passing over the dead surfaces a second coat of
deadening glue, which must be hotter than the first. This finishes the
work, and gives it strength.

_Leaf gilding_, on paper or vellum, is done by giving them a coat of gum
water or fine size, applying the gold leaf ere the surfaces be hard dry,
and burnishing with agate.

_Gold lettering_, on bound books, is given without size, by laying the
gold leaf on the leather, and imprinting it with hot brass types.

The _edges of the leaves of books are gilded_, while they are in the
press, where they have been cut smooth, by applying a solution of
isinglass in spirits, and laying-on the gold when the edges are in a
proper state of dryness. The French workmen employ a ground of Armenian
bole, mixed with powdered sugar-candy, by means of white of egg. This
ground is laid very thin upon the edges, after fine size or gum water
has been applied; and when the ground is dry it is rubbed smooth with a
wet rag, which moistens it sufficiently to take the gold.

_Japanners’ gilding_ is done by sprinkling or daubing with wash leather,
some gold powder, over an oil sized surface, mixed with oil of
turpentine. This gives the appearance of frosted gold. The gold powder
may be obtained, either by precipitating gold from its solution in _aqua
regia_ by a solution of pure sulphate of iron, or by evaporating away
the mercury from some gold amalgam.

II. _Chemical Gilding_, or the application of gold by chemical affinity
to metallic surfaces.

A compound of copper with one seventh of brass is the best metal for
gilding on; copper by itself being too soft and dark coloured. Ordinary
brass, however, answers very well. We shall describe the process of wash
gilding, with M. D’Arcet’s late improvements, now generally adopted in
Paris.

_Wash gilding_, consists in applying evenly an amalgam of gold to the
surface of a copper alloy, and dissipating the mercury with heat, so as
to leave the gold film fixed. The surface is afterwards burnished or
deadened at pleasure. The gold ought to be quite pure, and laminated to
facilitate its combination with the mercury; which should also be pure.

_Preparation of the amalgam._ After weighing the fine gold, the workman
puts it in a crucible, and as soon as this becomes faintly red, he pours
in the requisite quantity of mercury; which is about 8 to 1 of gold. He
stirs up the mixture with an iron rod, bent hookwise at the end, leaving
the crucible on the fire till he perceives that all the gold is
dissolved. He then pours the amalgam into a small earthen dish
containing water, washes it with care, and squeezes out of it with his
fingers all the running mercury that he can. The amalgam that now
remains on the sloping sides of the vessel is so pasty as to preserve
the impression of the fingers. When this is squeezed in a shamoy leather
bag, it gives up much mercury; and remains an amalgam, consisting of
about 33 of mercury, and 57 of gold, in 100 parts. The mercury which
passes through the bag, under the pressure of the fingers, holds a good
deal of gold in solution; and is employed in making fresh amalgam.

_Preparation of the mercurial solution._ The amalgam of gold is applied
to brass, through the intervention of pure nitric acid, holding in
solution a little mercury.

100 parts of mercury, and 110 parts by weight of pure nitric acid,
specific gravity 1·33, are to be put into a glass matrass. On the
application of a gentle heat the mercury dissolves with the
disengagement of fumes of nitrous gas, which must be allowed to escape
into the chimney. This solution is to be diluted with about 25 times its
weight of pure water, and bottled up for use.

1. _Annealing._--The workman anneals the piece of bronze after it has
come out of the bands of the turner and engraver. He sets it among
burning charcoal, or rather peats, which have a more equal and lively
flame; covering it quite up, so that it may be oxidized as little as
possible, and taking care that the thin parts of the piece do not become
hotter than the thicker. This operation is done in a dark room, and when
he sees the piece of a cherry red colour, he removes the fuel from about
it, lifts it out with long tongs, and sets it to cool slowly in the air.

2. The _decapage_.--The object of this process is to clear the surface
from the coat of oxide which may have formed upon it. The piece is
plunged into a bucket filled with extremely dilute sulphuric acid; it is
left there long enough to allow the coat of oxide to be dissolved, or at
least loosened; and it is then rubbed with a hard brush. When the piece
becomes perfectly bright, it is washed and dried. Its surface may
however be still a little variegated; and the piece is therefore dipped
in nitric acid, specific gravity 1·33, and afterwards rubbed with a
long-haired brush. The addition of a little common salt to the dilute
sulphuric acid would probably save the use of nitric acid, which is so
apt to produce a new coat of oxide. It is finally made quite dry, (after
washing in pure water) by being rubbed well with tanners’ dry bark,
saw-dust, or bran. The surface should now appear somewhat de-polished;
for when it is very smooth, the gold does not adhere so well.

3. _Application of the amalgam._--The gilder’s _scratch-brush_ or
pencil, made with fine brass wire is to be dipped into the solution of
nitrate of mercury, and is then to be drawn over a lump of gold amalgam,
laid on the sloping side of an earthen vessel, after which it is to be
applied to the surface of the brass. This process is to be repeated,
dipping the brush into the solution, and drawing it over the amalgam,
till the whole surface to be gilded is coated with its just proportion
of gold. The piece is then washed in a body of water, dried, and put to
the fire to volatilize the mercury. If one coat of gilding be
insufficient, the piece is washed over anew with amalgam, and the
operation recommenced till the work prove satisfactory.

4. _Volatilization of the mercury._--Whenever the piece is well coated
with amalgam, the gilder exposes it to glowing charcoal, turning it
about, and heating it by degrees to the proper point; he then withdraws
it from the fire, lifts it with long pincers, and, seizing it in his
left hand, protected by a stuffed glove, he turns it over in every
direction, rubbing and striking it all the while with a long-haired
brush, in order to equalize the amalgam. He now restores the piece to
the fire, and treats it in the same way till the mercury be entirely
volatilized, which he recognises by the hissing sound of a drop of water
let fall on it. During this time he repairs the defective spots, taking
care to volatilize the mercury very slowly. The piece, when thoroughly
coated with gold, is washed, and scrubbed well with a brush in water
acidulated with vinegar.

If the piece is to have some parts burnished, and others dead, the parts
to be burnished are covered with a mixture of Spanish white, bruised
sugar-candy, and gum dissolved in water. This operation is called in
French _epargner_ (_protecting_). When the gilder has _protected_ the
burnished points, he dries the piece, and carries the heat high enough
to expel the little mercury which might still remain on it. He then
plunges it, while still a little hot, in water acidulated with sulphuric
acid, washes it, dries it, and gives it the burnish.

5. The _burnish_ is given by rubbing the piece with burnishers of
hematite (bloodstone). The workman dips his burnisher in water sharpened
with vinegar, and rubs the piece always in the same direction backwards
and forwards, till it exhibits a fine polish, and a complete metallic
lustre. He then washes it in cold water, dries it with fine linen cloth,
and concludes the operation by drying it slowly on a grating placed
above a chafing dish of burning charcoal.

6. The _deadening_ is given as follows. The piece, covered with the
_protection_ on those parts that are to be burnished, is attached with
an iron wire to the end of an iron rod, and is heated strongly so as to
give a brown hue to the _epargne_ by its partial carbonization. The
gilded piece assumes thus a fine tint of gold; and is next coated over
with a mixture of sea salt, nitre, and alum, fused in the water of
crystallization of the latter salt. The piece is now restored to the
fire, and heated till the saline crust which covers it becomes
homogeneous, nearly transparent, and enters into true fusion. It is then
taken from the fire and suddenly plunged into cold water, which
separates the saline crust, carrying away even the coat of _epargne_.
The piece is lastly passed through very weak nitric acid, washed in a
great body of water, and dried by exposure either to the air, over a
drying stove, or with clean linen cloths.

7. _Of or-moulu colour._--When it is desired to put a piece of gilded
bronze into _or-moulu_ colour, it must be less scrubbed with the
scratch-brush than usual, and made to _come back again_ by heating it
more strongly than if it were to be deadened, and allowing it then to
cool a little. The _or-moulu_ colouring is a mixture of hematite, alum,
and sea salt. This mixture is to be thinned with vinegar, and applied
with a brush so as to cover the gilded brass, with reserve of the
burnished parts. The piece is then put on glowing coals, urged a little
by the bellows, and allowed to heat till the colour begins to blacken.
The piece ought to be so hot that water sprinkled on it may cause a
hissing noise. It is then taken from the fire, plunged into cold water,
washed, and next rubbed with a brush dipped in vinegar, if the piece be
smooth, but if it be chased, weak nitric acid must be used. In either
case, it must be finally washed in a body of pure water, and dried over
a gentle fire.

8. _Of red gold colour._--To give this hue, the piece after being coated
with amalgam, and heated, is in this hot state to be suspended by an
iron wire, and tempered with the composition known under the name of
gilder’s wax; made with yellow wax, red ochre, verdigris, and alum. In
this state it is presented to the flame of a wood fire, is heated
strongly, and the combustion of its coating is favoured by throwing some
drops of the wax mixture into the burning fuel. It is now turned round
and round over the fire, so that the flame may act equally. When all the
wax of the colouring is burned away, and when the flame is extinguished,
the piece is to be plunged in water, washed, and scrubbed with the
scratch-brush and pure vinegar. If the colour is not beautiful, and
quite equal in shade, the piece is coated with verdigris dissolved in
vinegar, dried over a gentle fire, plunged in water, and scrubbed with
pure vinegar, or even with a little weak nitric acid if the piece
exhibit too dark a hue. It is now washed, burnished, washed anew, wiped
with linen cloth, and finally dried over a gentle fire.

The following is the outline of a complete, gilding factory, as now
fitted up at Paris.

[Illustration: 529]

_Fig._ 529. Front elevation and plan of a complete gilding workshop.

P. Furnace of _appel_, or draught, serving at the same time to heat the
deadening pan (_poêlon au mat_).

F. Ashpit of this furnace.

N. Chimney of this furnace constructed of bricks, as far as the
contraction of the great chimney S of the forge, and which is terminated
by a summit pipe rising 2 or 3 yards above this contraction.

B. Forge for annealing the pieces of bronze; for drying the gilded
pieces, &c.

C. Chimney of communication between the annealing forge B, and the space
D below the forge. This chimney serves to carry the noxious fumes into
the great vent of the factory.

U. Bucket for the brightening operation.

A. Forge for passing the amalgam over the piece.

R. Shelf for the brushing operations.

E E. Coal cellarets.

O. Forge for the deadening process.

G. Furnace for the same.

M. An opening into the furnace of _appel_, by which vapours may be let
off from any operation by taking out the plug at M.

I. Cask in which the pieces of gilded brass are plunged for the
deadening process. The vapours rising thence are carried up the general
chimney.

J J. Casement with glass panes, which serves to contract the opening of
the hearths, without obstructing the view. The casement may be rendered
movable to admit larger objects.

H H. Curtains of coarse cotton cloth, for closing at pleasure, in whole
or part, one or several of the forges or hearths, and for quickening the
current of air in the places where the curtains are not drawn.

Q. Opening above the draught furnace, which serves for the heating of
the _poêlon au mat_ (deadening pan).

_Gilding on polished iron and steel._--If a nearly neutral solution of
gold in muriatic acid, be mixed with sulphuric ether, and agitated, the
ether will take up the gold, and float above the denser acid. When this
auriferous ether is applied by a hair pencil to brightly polished iron
or steel, the ether flies off, and the gold adheres. It must be fixed by
polishing with the burnisher. This gilding is not very rich or durable.
In fact the affinity between gold and iron is feeble, compared to that
between gold and copper or silver. But polished iron, steel, and copper,
may be gilded with heat, by gold leaf. They are first heated till the
iron takes a bluish tint, and till the copper has attained to a like
temperature; a first coat of gold leaf is now applied, which is pressed
gently down with a burnisher, and then exposed to a gentle heat.
Several leaves either single or double are thus applied in succession,
and the last is burnished down cold.

_Cold gilding._--Sixty grains of fine gold and 12 of rose copper are to
be dissolved in two ounces of aqua regia. When the solution is
completed, it is to be dropped on clean linen rags, of such bulk as to
absorb all the liquid. They are then dried, and burned into ashes. These
ashes contain the gold in powder.

When a piece is to be gilded, after subjecting it to the preliminary
operations of softening or annealing and brightening, it is rubbed with
a moistened cork, dipped in the above powder, till the surface seems to
be sufficiently gilded. Large works are thereafter burnished with pieces
of hematite, and small ones with steel burnishers, along with soap
water.

In gilding small articles, as buttons, with amalgam, a portion of this
is taken equivalent to the work to be done, and some nitrate of mercury
solution is added to it in a wooden trough; the whole articles are now
put in, and well worked about with a hard brush, till their surfaces are
equably coated. They are then washed, dried, and put altogether into an
iron frying-pan, and heated till the mercury begins to fly off, when
they are turned out into a cap, in which they are tossed and well
stirred about with a painter’s brush. The operation must be repeated
several times for a strong gilding. The surfaces are finally brightened
by brushing them along with small beer or ale grounds.

_Gold wire_, is formed by drawing a cylindrical rod of the metal as pure
as may be, through a series of holes punched in an iron plate,
diminishing progressively in size. The gold as it is drawn through,
becomes hardened by the operation, and requires frequent annealing.

_Gold thread_, or _spun gold_, is a flatted silver-gilt wire, wrapped or
laid over a thread of yellow silk, by twisting with a wheel and iron
bobbins. By the aid of a mechanism like the Braiding Machine, a number
of threads may thus be twisted at once by one master wheel. The
principal nicety consists in so regulating the movements that the
successive volutions of the flatted wire on each thread may just touch
one another, and form a continuous covering. The French silver for
gilding is said to be alloyed with 5 or 6 pennyweights, and ours with 12
pennyweights of copper in the pound troy. The gold is applied in leaves
of greater or less thickness, according to the quality of the gilt wire.
The smallest proportion formerly allowed in this country by act of
parliament, was 100 grains of gold to one pound, or 5760 grains of
silver; but more or less may now be used. The silver rod is encased in
the gold leaf, and the compound cylinder is then drawn into round wire
down to a certain size, which is afterwards flatted in a rolling mill
such as is described under MINT.

The liquor employed by goldsmiths to bring out a rich colour upon the
surface of their trinkets, is made by dissolving 1 part of sea-salt, 1
part of alum, 2 parts of nitre, in 3 or 4 of water. This pickle or
sauce, as it is called, takes up not only the copper alloy, but a
notable quantity of gold; the total amount of which in the Austrian
empire, has been estimated annually at 47,000 francs. To recover this
gold, the liquor is diluted with at least twice its bulk of boiling
water; and a solution of very pure green sulphate of iron is poured into
it. The precipitate of gold is washed upon a filter, dried, and purified
by melting in a crucible along with a mixture of equal parts of nitre
and borax.


GONG-GONG; or _tam-tam_ of the Chinese; a kind of cymbal made of a
copper alloy, described towards the end of the article COPPER.


GONIOMETER, is the name of a little instrument made either on mechanical
or optical principles, for measuring the angles of crystals. It is
indispensable to the mineralogist.

[Illustration: 530]


GRADUATOR, called by its contriver M. Wagenmann, _Essigbilder_, which
means in German, vinegar-maker, is represented _fig._ 530. It is an
oaken tub, 5-1/2 feet high, 3-1/2 feet wide at top, and 3 at bottom, set
upon wooden beams, which raise its bottom about 14 inches from the
floor. At a distance of 15 inches above the bottom, the tub is pierced
with a horizontal row of 8 equidistant round holes, of an inch in
diameter. At 5 inches beneath the mouth of the tub, a thick beech-wood
hoop is made fast to the inner surface, which supports a circular oaken
shelf, leaving a space round its edge of 1-1/4 inches, which is stuffed
water tight with hemp or tow. In this shelf, 400 holes at least must be
bored, about 1/8 of an inch in diameter, and 1-1/2 inches apart; and
each of these must be loosely filled with a piece of packthread, or
cotton wick, which serves to filter the liquid slowly downwards. In the
same shelf there are likewise four larger holes of 1-1/2 inches
diameter, and 18 inches apart, each of which receives air-tight a glass
tube 3 or 4 inches long, having its ends projecting above and below the
shelf. These tubes serve to allow the air that enters by the 8
circumferential holes, to circulate freely through the graduator. The
mouth of the tube is covered with a wooden lid, in whose middle is a
hole for the insertion of a funnel, when the liquor of acetification
requires to be introduced. One inch above the bottom, a hole is bored
for receiving a syphon-formed discharge pipe, whose upper curvature
stands one inch below the level of the holes in the side of the tub, to
prevent the liquor from rising so high as to overflow through them. The
syphon is so bent as to retain a body of liquor 12 inches deep above the
bottom of the tub, and to allow the excess only to escape into the
subjacent receiver. In the upper part of the graduator, but under the
shelf, the bulb of a thermometer is inserted through the side, some way
into the interior, having a scale exteriorly. The whole capacity of the
cask from the bottom up to within one inch of the perforated shelf, is
to be filled with thin shavings of beech wood, grape stalks or birch
twigs, previously imbued with vinegar. The manner of using this simple
apparatus, is described under ACETIC ACID.


GRANITE, is a compound rock, essentially composed of quartz, felspar,
and mica, each in granular crystals. It constitutes the lowest of the
geological formations, and therefore has been supposed to serve as a
base to all the rest. It is the most durable material for building, as
many of the ancient Egyptian monuments testify.

The obelisk in the place of Saint Jean de Lateran at Rome, which was
quarried at Syene, under the reign of Zetus, king of Thebes, 1300 years
before the Christian era; and the one in the place of Saint Pierre, also
at Rome, consecrated to the Sun by a son of Sesostris, have resisted the
weather for fully 3000 years. On the other hand there are many granites,
especially those in which felspar predominates, which crack and crumble
down in the course of a few years. In the same mountain, or even in the
same quarry, granites of very different qualities as to soundness and
durability occur. Some of the granites of Cornwall and Limousin readily
resolve themselves into a white kaolin or argillaceous matter, from
which pottery and porcelain are made.

Granite when some time dug out of the quarry, becomes refractory, and
difficult to cut. When this rock is intended to be worked it should be
kept under water; and that variety ought to be selected which contains
least felspar, and in which the quartz or gray crystals predominate.


GRANULATION, is the process by which metals are reduced to minute
grains. It is effected by pouring them in a melted state, through an
iron cullender pierced with small holes, into a body of water; or
directly upon a bundle of twigs immersed in water. In this way copper is
granulated into bean shot, and silver alloys are granulated preparatory
to PARTING; which see.


GRAPHITE; (_Plombagine_, Fr.; _Reissblei_, Germ.) is a mineral substance
of a lead or iron gray colour, a metallic lustre, soft to the touch, and
staining the fingers with a lead gray hue. Spec. grav. 2·08 to 2·45. It
is easily scratched, or cut with a steel edge, and displays the metallic
lustre in its interior. Burns with great difficulty in the outward flame
of the blow-pipe. It consists of carbon in a peculiar state of
aggregation, with an extremely minute and apparently accidental
impregnation of iron. Graphite, called also plumbago and black lead,
occurs in gneiss, mica slate, and their subordinate clay slates and lime
stones; in the form of masses, veins, and kidney-shaped disseminated
pieces; as also in the transition slate, as at Borrodale in Cumberland,
where the most precious deposit exists, both in reference to extent and
quality for making pencils. It has been found also among the coal
strata, as near Cumnock in Ayrshire. This substance is employed for
counteracting friction between rubbing surfaces of wood or metal, for
making crucibles and portable furnaces, for giving a gloss to the
surface of cast iron, &c. See PLUMBAGO, for some remarks concerning the
Cumberland mine.


GRAUWACKE or GREYWACKE, is a rock formation, composed of pieces of
quartz, flinty slate, felspar and clay slate, cemented by a clay-slate
basis; the pieces varying in size from small grains to a hen’s egg.


GRAY DYE. (_Teinture grise_, Fr.; _Graufarbe_, Germ.) The gray dyes in
their numerous shades, are merely various tints of black, in a more or
less diluted state, from the deepest to the lightest hue.

The dyeing materials are essentially the tannic and gallic acid of galls
or other astringents, along with the sulphate or acetate of iron, and
occasionally wine stone. Ash gray is given for 30 pounds of woollen
stuff, by one pound of gall-nuts, 1/2 lib. of wine stone (crude tartar),
and 2-1/2 libs. of sulphate of iron. The galls and the wine stone being
boiled with from 70 to 80 pounds of water, the stuff is to be turned
through the decoction at a boiling heat for half an hour, then taken
out, when the bath being refreshed with cold water, the copperas is to
be added, and, as soon as it is dissolved, the stuff is to be put in and
fully dyed. Or, for 36 pounds of wool; 2 pounds of tartar, 1/2 pound of
galls, 3 pounds of sumach, and 2 pounds of sulphate of iron are to be
taken. The tartar being dissolved in 80 pounds of boiling water, the
wool is to be turned through the solution for half an hour, and then
taken out. The copper being filled up to its former level with fresh
water, the decoction of the galls and sumach is to be poured in, and
the wool boiled for half an hour in the bath. The wool is then taken
out, while the copperas is being added and dissolved; after which it is
replaced in the bath, and dyed gray with a gentle heat.

If the gray is to have a yellow cast, instead of the tartar, its own
weight of alum is to be taken; instead of the galls, one pound of old
fustic; instead of the copperas, 3/4 of a pound of Saltzburg vitriol,
which consists, in 22-3/8 parts, of 17 of sulphate of iron, and 5-3/8 of
sulphate of copper; then proceed as above directed. Or the stuff may be
first stained in a bath of fustic, next in a weak bath of galls with a
little alum; then the wool being taken out, a little vitriol, (common or
Saltzburg) is to be put in, previously dissolved in a decoction of
logwood; and in this bath the dye is completed.

_Pearl-gray_ is produced by passing the stuff first through a decoction
of sumach and logwood (2 libs. of the former to one of the latter),
afterwards through a dilute solution of sulphate or acetate of iron; and
finishing it in a weak bath of weld containing a little alum.
_Mouse-gray_ is obtained, when with the same proportions as for
ash-gray, a small quantity of alum is introduced.

For several other shades, as tawny-gray, iron-gray, and slate-gray, the
stuff must receive a previous blue ground by dipping it in the indigo
vat; then it is passed first through a boiling bath of sumach with
galls, and lastly through the same bath at a lower temperature after it
has received the proper quantity of solution of iron.

For dyeing silk gray, fustet, logwood, sumach, and elder-tree bark, are
employed instead of galls. Archil and annotto are frequently used to
soften and beautify the tint.

The mode of producing gray dyes upon cotton has been sufficiently
explained in the articles CALICO PRINTING and DYEING.


GREEN DYE is produced by the mixture of a blue and yellow dye, the blue
being first applied. See DYEING; as also BLUE and YELLOW DYES, and
CALICO PRINTING.


GREEN PAINTS. (_Couleurs vertes_, Fr.; _Grüne pigmente_, Germ.) Green,
which is so common a colour in the vegetable kingdom, is very rare in
the mineral. There is only one metal, copper, which affords in its
combinations the various shades of green in general use. The other
metals capable of producing this colour are, chromium in its protoxide,
nickel in its hydrated oxide, as well as its salts, the seleniate,
arseniate, and sulphate; and titanium in its prussiate.

Green pigments are prepared also by the mixture of yellows and blues;
as, for example, the green of Rinman and of Gellert, obtained by the
mixture of cobalt blue, and flowers of zinc; that of Barth made with
yellow lake, prussian blue, and clay; but these paints seldom appear in
the market, because the greens are generally extemporaneous preparations
of the artists.

_Mountain green_ consists of the hydrate, oxide, or carbonate of copper,
either factitious, or as found in nature.

_Bremen or Brunswick green_ is a mixture of carbonate of copper with
chalk or lime, and sometimes a little magnesia or ammonia. It is
improved by an admixture of white lead. It may be prepared by adding
ammonia to a mixed solution of sulphate of copper and alum.

_Frise green_ is prepared with sulphate of copper and sal ammoniac.

_Mittis green_ is an arseniate of copper; made by mixing a solution of
acetate or sulphate of copper with arsenite of potash. It is in fact
Scheele’s green.

_Sap green_ is the inspissated juice of buckthorn berries. These are
allowed to ferment for 8 days in a tub, then put in a press, adding a
little alum to the juice, and concentrated by gentle evaporation. It is
lastly put up in pigs’ bladders, where it becomes dry and hard.

_Schweinfurt green_; see SCHWEINFURT.

_Verona green_ is merely a variety of the mineral called green earth.


GREEN VITRIOL is sulphate of iron in green crystals.


GUAIAC; (_Gaiac_, Fr.; _Guajaharz_, Germ.) is a resin which exudes from
the trunk of the _Guaiacum officinale_, a tree which grows in the West
India islands. It comes to us in large greenish-brown, semi-transparent
lumps, having a conchoidal or splintery fracture, brittle and easy to
pulverize. It has an aromatic smell, a bitterish, acrid taste, melts
with heat, and has a spec. grav. of from 1·20 to 1·22. It consists of
67·88 carbon; 7·05 hydrogen; and 25·07 oxygen; and contains two
different resins, the one of which is soluble in all proportions in
ammonia, and the other forms, with water of ammonia, a tarry
consistenced mixture. It is soluble in alkaline lyes, in alcohol,
incompletely in ether, still less so in oil of turpentine, and not at
all in fat oils. Its chief use is in medicine.


GUANO; is a substance of a dark yellow colour; of a strong ambrosial
smell; which blackens in the fire, with the exhalation of an ammoniacal
odour; soluble with effervescence in hot nitric acid. When this solution
is evaporated to dryness, it assumes a fine red colour, evincing the
presence of uric acid. Guano is found upon the coasts of Peru, in the
islands of Chinche, near Pisco, and several other places more to the
south. It forms a deposit 50 or 60 feet thick, and of considerable
extent; and appears to be the accumulation of the excrements of
innumerable flocks of birds, especially herons and flamands, which
inhabit these islands. It is an excellent manure, and forms the object
of a most extensive and profitable trade.


GUM; (_Gomme_, Fr.; _Gummi_, _Pflanzenschleim_, Germ.) is the name of a
proximate vegetable product, which forms with water a slimy solution,
but is insoluble in alcohol, ether, and oils; it is converted by strong
sulphuric acid into oxalic and mucic acids.

There are six varieties of gum: 1. gum arabic; 2. gum senegal; 3. gum of
the cherry and other stone fruit trees; 4. gum tragacanth; 5. gum of
Bassora; 6. the gum of seeds and roots. The first five spontaneously
flow from the branches and trunks of their trees, and sometimes from the
fruits, in the form of a mucilage which dries and hardens in the air.
The sixth kind is extracted by boiling water.

Gum arabic and gum senegal consist almost wholly of the purest gum
called _arabine_ by the French chemists; our native fruit trees contain
some _cerasine_, along with arabine; the gum of Bassora and gum
tragacanth consist of arabine and bassorine.

_Gum arabic_, flows from the _acacia arabica_, and the _acacia vera_,
which grow upon the banks of the Nile and in Arabia. It occurs in
commerce in the form of small pieces, rounded upon one side and hollow
upon the other. It is transparent, without smell, brittle, easy to
pulverize, sometimes colourless, sometimes with a yellow or brownish
tint. It may be bleached by exposure to the air and the sun-beams, at
the temperature of boiling water. Its specific gravity is 1·355,
Moistened gum arabic reddens litmus paper, owing to the presence of a
little supermalate of lime, which may be removed by boiling alcohol; it
shows also traces of the chlorides of potassium and calcium, and the
acetate of potash. 100 parts of good gum, contain 70·40 of arabine,
17·60 of water, with a few per cents. of saline and earthy matters. Gum
arabic is used in medicine, as also to give lustre to crapes and other
silk stuffs.

_Gum senegal_, is collected by the negroes during the month of November,
from the _acacia senegal_, a tree 18 or 20 feet high. It comes to us in
pieces about the size of a partridge egg, but sometimes larger, with a
hollow centre. Its specific gravity is 1·436. It consists of 81·10
arabine; 16·10 water; and from 2 to 3 of saline matters. The chemical
properties and uses of this gum are the same as those of gum arabic. It
is much employed in calico-printing.

_Cherry-tree gum_, consists of 52·10 arabine; 54·90 cerasine; 12 water;
and 1 saline matter.

_Gum tragacanth_, is gathered about the end of June, from the
_astragalus tragacantha_ of Crete and the surrounding islands. It has
the appearance of twisted ribands; is white or reddish; nearly opaque,
and a little ductile. It is difficult to pulverize, without heating the
mortar. Its specific gravity is 1·384. When plunged in water, it
dissolves in part, swells considerably, and forms a very thick mucilage.
100 parts of it consist of 53·30 arabine; 33·30 bassorine and starch;
11·0 water; and from 2 to 3 parts of saline matters. It is employed in
calico printing, and by shoemakers.

_Gum of Bassora_; see BASSORINE.

_Gum of seeds_, as linseed, consists of 52·70 arabine; 28·9 of an
insoluble matter; 10·3 water; and 7·11 saline matter. Neither bassorine
nor cerasine seems to be present in seeds and roots. For _British Gum_,
see STARCH.


GUM RESINS. (_Gomme-résines_, Fr.; _Schleimharze_, Germ.) When incisions
are made in the stems, branches and roots of certain plants, a milky
juice exudes, which gradually hardens in the air; and appears to be
formed of resin and essential oil, held suspended in water charged with
gum, and sometimes with other vegetable matters, such as caoutchouc,
bassorine, starch, wax, and several saline matters. The said concrete
juice is called a gum-resin; an improper name, as it gives a false idea
of the nature of the substance. They are all solid; heavier than water;
in general opaque and brittle; many have an acrid taste, and a strong
smell; their colour is very variable. They are partially soluble in
water, and also in alcohol; and the solution in the former liquid seldom
becomes transparent. Almost all the gum resins are medicinal substances,
and little employed in the arts and manufactures. The following is a
list of them: Asa-fœtida; gum ammoniac; bdellium; euphorbium; galbanum;
gamboge; myrrh; olibanum or frankincense; opoponax; and scammony. Some
of these are described in this work under their peculiar names.


GUNPOWDER. The following memoir upon this subject was published by me in
the Journal of the Royal Institution for October, 1830. It contains the
results of several careful analytical experiments, as also of
observations made at the Royal Gunpowder Works at Waltham Abbey, and at
some similar establishments in the neighbourhood of London.

GUNPOWDER is a mechanical combination of nitre, sulphur, and charcoal;
deriving the intensity of its explosiveness from the purity of its
constituents, the proportion in which they are mixed, and the intimacy
of the admixture.

1. _On the nitre._--Nitre may be readily purified, by solution in water
and crystallization, from the muddy particles and foreign salts with
which it is usually contaminated. In a saturated aqueous solution of
nitre, boiling hot, the temperature is 240° F.; and the relation of the
salt to its solvent is in weight as three to one, by my experiments: not
five to one, as MM. Bottée and Riffault have stated. We must not,
however, adopt the general language of chemists, and say that three
parts of nitre are soluble in one of boiling water, since the liquid has
a much higher heat and greater solvent power than this expression
implies.

Water at 60° dissolves only one-fourth of its weight of nitre; or, more
exactly, this saturated solution contains 21 per cent. of salt. Its
specific gravity is 1·1415; 100 parts in volume of the two constituents
occupy now 97·91 parts. From these data we may perceive that little
advantage could be gained in refining crude nitre, by making a
boiling-hot saturated solution of it; since on cooling, the whole would
concrete into a moist saline mass, consisting by weight of 2-3/4 parts
of salts, mixed with 1 part of water, holding 1/4 of salt in solution,
and in bulk of 1-7/8 of salt, with about 1 of liquid; for the specific
gravity of nitre is 2·005, or very nearly the double of water. It is
better, therefore, to use equal weights of saltpetre and water in making
the boiling-hot solution. When the filtered liquid is allowed to cool
slowly, somewhat less than three-fourths of the nitre will separate in
regular crystals; while the foreign salts that were present will remain
with fully one-fourth of nitre in the mother liquor. On redissolving
these crystals with heat, in about two-thirds of their weight of water,
a solution will result, from which crystalline nitre, fit for every
purpose, will concrete on cooling.

As the principal saline impurity of saltpetre is muriate of soda (a
substance scarcely more soluble in hot than in cold water), a ready mode
thence arises of separating that salt from the nitre in mother waters
that contain them in nearly equal proportion. Place an iron ladle or
basin, perforated with small holes, on the bottom of the boiler in which
the solution is concentrating. The muriate, as it separates by the
evaporation of the water, will fall down and fill the basin, and may be
removed from time to time. When small needles of nitre begin to appear,
the solution must be run off into the crystallizing cooler, in which
moderately pure nitre will be obtained, to be refined by another similar
operation.

At the Waltham Abbey gunpowder works the nitre is rendered so pure by
successive solutions and crystallizations, that it causes no opalescence
in a solution of nitrate of silver. Such crystals are dried, fused in an
iron pot at a temperature of from 500° to 600° F., and cast into moulds.
The cakes are preserved in casks.

About the period of 1794 and 1795, under the pressure of the first wars
of their revolution, the French chemists employed by the government
contrived an expeditious, economical, and sufficiently effective mode of
purifying their nitre. It must be observed that this salt, as brought to
the gunpowder-works in France, is in general a much cruder article than
that imported into this country from India. It is extracted from the
nitrous salts contained in the mortar-rubbish of old buildings,
especially those of the lowest and filthiest descriptions. By their
former methods, the French could not refine their nitre in less time
than eight or ten days; and the salt was obtained in great lumps, very
difficult to dry and divide; whereas the new process was so easy and so
quick, that in less than twenty-four hours, at one period of pressure,
the crude saltpetre was converted into a pure salt, brought to perfect
dryness, and in such a state of extreme division as to supersede the
operations of grinding and sifting, whence also considerable waste was
avoided.

The following is a brief outline of this method, with certain
improvements, as now practised in the establishment of the
_Administration des poudres et salpêtres_, in France.

The refining boiler is charged over night with 600 kilogrammes of water,
and 1200 kilogrammes of saltpetre, as delivered by the salpêtriers. No
more fire is applied than is adequate to effect the solution of this
first charge of saltpetre. It may here be observed, that such an article
contains several deliquescent salts, and is much more soluble than pure
nitre. On the morrow morning the fire is increased, and the boiler is
charged at different intervals with fresh doses of saltpetre, till the
whole amounts to 3000 kilogrammes. During these additions, care is taken
to stir the liquid very diligently, and to skim off the froth as it
rises. When it has been for some time in ebullition, and when it may be
presumed that the solution of the nitrous salts is effected, the muriate
of soda is scooped out from the bottom of the boiler, and certain
affusions or inspersions of cold water are made into the pot, to quicken
the precipitation of that portion which the boiling motion may have kept
afloat. When no more is found to fall, one kilogramme of Flanders glue,
dissolved in a sufficient quantity of hot water, is poured into the
boiler; the mixture is thoroughly worked together, the froth being
skimmed off, with several successive inspersions of cold water, till 400
additional kilogrammes have been introduced, constituting altogether
1000 kilogrammes.

When the refining liquor affords no more froth, and is grown perfectly
clear, all manipulation must cease. The fire is withdrawn, with the
exception of a mere kindling, so as to maintain the temperature till the
next morning at about 88° C. = 190·4 F.

This liquor is now transferred by hand-basins into the crystallizing
reservoirs, taking care to disturb the solution as little as possible,
and to leave untouched the impure matter at the bottom. The contents of
the long crystallizing cisterns are stirred backwards and forwards with
wooden paddles, in order to quicken the cooling, and the consequent
precipitation of the nitre in minute crystals. These are raked as soon
as they fall, to the upper end of the doubly-inclined bottom of the
crystallizer, and thence removed to the washing chests or boxes. By the
incessant agitation of the liquor, no large crystals of nitre can
possibly form. When the temperature has fallen to within 7° or 8° F., of
the apartment, that is, after seven or eight hours, all the saltpetre
that it can yield will have been obtained. By means of the double inward
slope given to the crystallizer, the supernatant liquid is collected in
the middle of the breadth, and may be easily laded out.

The saltpetre is shovelled out of the crystallizer into the washing
chests, and heaped up in them so as to stand about six or seven inches
above their upper edges, in order to allow for the subsidence which it
must experience in the washing process. Each of these chests being thus
filled, and their bottom holes being closed with plugs, the salt is
besprinkled from the rose of a watering-can, with successive quantities
of water saturated with saltpetre, and also with pure water, till the
liquor, when allowed to run off, indicates by the hydrometer, a
saturated solution. The water of each sprinkling ought to remain on the
salt for two or three hours; and then it may be suffered to drain off
through the plug-holes below, for about an hour.

All the liquor of drainage from the first watering, as well as a portion
of the second, is set aside, as being considerably loaded with the
foreign salts of the nitre, in order to be evaporated in the sequel with
the mother waters. The last portions are preserved, because they contain
almost nothing but nitre, and may therefore serve to wash another dose
of that salt. It has been proved by experience, that the quantity of
water employed in washing need never exceed thirty-six sprinklings in
the whole, composed of three waterings, of which the first two consist
of fifteen, and the last of six pots = 3 gallons E.; or in other words,
of fifteen sprinklings of water saturated with saltpetre, and twenty-one
of pure water.

The saltpetre, after remaining five or six days in the washing chests,
is transported into the drying reservoirs, heated by the flue of the
nearest boiler; here it is stirred up from time to time with wooden
shovels, to prevent its adhering to the bottom, or running into lumps,
as well as to quicken the drying process. In the course of about four
hours, it gets completely dry, in which state it no longer sticks to the
shovel, but falls down into a soft powder by pressure in the hand, and
is perfectly white and pulverulent. It is now passed through a brass
sieve, to separate any small lumps or foreign particles accidentally
present, and is then packed up in bags or barrels. Even in the shortest
winter days, the drying basin may be twice charged, so as to dry 700 or
800 kilogrammes. By this operation, the nett produce of 3000 kilogrammes
(3 tons) thus refined, amounts to from 1750 to 1800 kilogrammes of very
pure nitre, quite ready for the manufacture of gunpowder.

The mother waters are next concentrated; but into their management it is
needless to enter in this memoir.

On reviewing the above process as practised at present, it is obvious
that, to meet the revolutionary crisis, its conductors must have
shortened it greatly, and have been content with a brief period of
drainage.

2. _On the sulphur._--The sulphur now imported into this country, from
the volcanic districts of Sicily and Italy, for our manufactories of
sulphuric acid, is much purer than the sulphur obtained by artificial
heat from any varieties of pyrites, and may, therefore, by simple
processes, be rendered a fit constituent of the best gunpowder. As it
not my purpose here to repeat what may be found in common chemical
compilations, I shall say nothing of the sublimation of sulphur; a
process, moreover, much too wasteful for the gunpowder-maker.

Sulphur may be most easily analyzed, even by the manufacturer himself;
for I find it to be soluble in one tenth of its weight of boiling oil of
turpentine, at 316° Fahrenheit, forming a solution which remains clear
at 180°. As it cools to the atmospheric temperature, beautiful
crystalline needles form, which may be washed sufficiently with cold
alcohol, or even tepid water. The usual impurities of the sulphur, which
are carbonate and sulphate of zinc, oxide and sulphuret of iron,
sulphuret of arsenic and silica, will remain unaffected by the volatile
oil, and may be separately eliminated by the curious, though such
separation is of little practical importance.

Two modes of refining sulphur for the gunpowder works have been
employed; the first is by fusion, the second by distillation. Since the
combustible solid becomes as limpid as water, at the temperature of
about 230° Fahrenheit, a ready mode offers of removing at once its
denser and lighter impurities, by subsidence and skimming. But I may
take the liberty of observing, that the French melting pot, as described
in the elaborate work of MM. Bottée and Riffault, is singularly
ill-contrived, for the fire is kindled right under it, and plays on its
bottom. Now a pot for subsidence ought to be cold set; that is, should
have its bottom part imbedded in clay or mortar for four or six inches
up the side, and be exposed to the circulating flame of the fire only
round its middle zone. This arrangement is adopted in many of our great
chemical works, and is found to be very advantageous. With such a
boiler, judiciously heated, I believe that crude sulphur might be made
remarkably pure; whereas by directing the heat against the bottom of the
vessel, the crudities are tossed up, and incorporated with the mass. See
EVAPORATION.

The sulphur of commerce occurs in three prevailing colours; lemon yellow
verging on green, dark yellow, and brown yellow. As these different
shades result from the different degrees of heat to which it has been
exposed in its original extraction on the great scale, we may thereby
judge to what point it may still be heated anew in the refinery melting.
Whatever be the actual shade of the crude article, the art of the
refiner consists in regulating the heat, so that after the operation it
may possess a brilliant yellow hue, inclining somewhat to green.

In seeking to accomplish this purpose, the sulphur should first be
sorted according to its shades; and if a greenish variety is to be
purified, since this kind has been but little heated in its extraction,
the fusion may be urged pretty smartly, or the fire may be kept up till
every thing is melted but the uppermost layer.

Sulphur of a strong yellow tinge cannot bear so great a heat, and
therefore the fire must be withdrawn whenever three fourths of the whole
mass have been melted.

Brown-coloured brimstone, having been already somewhat scorched, should
be heated as little as possible, and the fire may be removed as soon as
one half of the mass is fused.

Instead of melting, separately, sulphurs of different shades, we shall
obtain a better result by first filling up the pot to half its capacity,
with the greenish-coloured article, putting over this layer one quarter
volume of the deep yellow, and filling it to the brim with the
brown-coloured. The fire must be extinguished as soon as the yellow is
fused. The pot must then be closely covered for some time; after which
the lighter impurities will be found on the surface in a black froth,
which is skimmed off, and the heavier ones sink to the bottom. The
sulphur itself must be left in the pot for ten or twelve hours, after
which it is laded out into the crystallizing boxes or casks.

Distillation affords a more complete and very economical means of
purifying sulphur, which was first introduced into the French gunpowder
establishments, when their importation of the best Italian and Sicilian
sulphur was obstructed by the British navy. Here the sulphur need not
come over slowly in a rare vapour, and be deposited in a pulverulent
form called flowers; for the only object of the refiner is to bring over
the whole of the pure sulphur into his condensing chamber, and to leave
all its crudities in the body of the still. Hence a strong fire is
applied to elevate a denser mass of vapours, of a yellowish colour,
which passing over into the condenser, are deposited in a liquid state
on its bottom, whilst only a few lighter particles attach themselves to
the upper and lateral surfaces. The refiner must therefore give to the
heat in this operation very considerable intensity; and, at some height
above the edge of the boiler, he should provide an inclined plane, which
may let the first ebullition of the sulphur overflow into a safety
recipient. The condensing chamber should be hot enough to maintain the
distilled sulphur in a fluid state,--an object most readily procured by
leading the pipes of several distilling pots into it; while the
continuity of the operations is secured, by charging each of the stills
alternately, or in succession. The heat of the receiver must be never so
high as to bring the sulphur to a syrupy consistence, whereby its colour
is darkened.

In the sublimation of sulphur, a pot containing about four cwt. can be
worked off only once in twenty-four hours, from the requisite moderation
of its temperature, and the precaution of an inclined plane, which
restores to it the accidental ebullitions. But, by distillation, a pot
containing fully ten cwt. may complete one process in nine hours at
most, with a very considerable saving of fuel. In the former plan of
procedure, an interval must elapse between the successive charges; but
in the latter, the operation must be continuous to prevent the apparatus
from getting cooled: in sublimation, moreover, where communication of
atmospheric air to the condensing chamber is indispensable, explosive
combustions of the sulphurous vapours frequently occur, with a copious
production of sulphurous acid, and correspondent waste of the sulphur;
disadvantages from which the distillatory process is in a great measure
exempt.

I shall here describe briefly the form and dimensions of the distilling
apparatus employed at Marseilles in purifying sulphur for the national
gunpowder works, which was found adequate to supply the wants of
Napoleon’s great empire. This apparatus consists of only two still-pots
of cast iron, formed like the large end of an egg, each about three feet
in diameter, two feet deep, and nearly half an inch thick at the bottom,
but much thinner above, with a horizontal ledge four inches broad. A pot
of good cast iron is capable of distilling 1000 tons of sulphur before
it is rendered unserviceable, by the action of the brimstone on its
substance, aided by a strong red heat. The pot is covered in with a
sloping roof of masonry, the upper end of which abuts on the brickwork
of the vaulted dome of condensation. A large door is formed in the
masonry in front of the mouth of the pot, through which it is charged
and cleared out; and between the roof-space over the pot, and the cavity
of the vault, a large passage is opened. At the back of the pot a
stone-step is raised to prevent the sulphur boiling over into the
condenser. The vault is about ten feet wide within, and fourteen feet
from the bottom up to the middle of the dome, which is perforated, and
carries a chimney about twelve feet high, and twelve feet diameter
inside.

As the dome is exposed to the expansive force of a strong heat, and to a
very considerable pressure of gases and vapours, it must possess great
solidity, and be therefore bound with iron straps. Between the still and
the contiguous wall of the condensing chamber, a space must be left for
the circulation of air; a precaution found by experience indispensable;
for the contact of the furnaces would produce on the wall of the chamber
such a heat as to make it crack and form crevices for the liquid sulphur
to escape. The sides of the chamber are constructed of solid masonry,
forty inches thick, surmounted by a brick dome, covered with a layer of
stones. The floor is paved with tiles, and the walls are lined with them
up to the springing of the dome; a square hole being left in one side,
furnished with a strong iron door, at which the liquid sulphur is drawn
off at proper intervals. In the roof of the vault are two valve-holes
covered with light plates of sheet-iron, which turn freely on hinges at
one end, so as to give way readily to any sudden expansion from within,
and thus prevent dangerous explosions.

As the chamber of condensation is an oblong square, terminating upwards
in an oblong vault, it consists of a parallelopiped below, and
semi-cylinder above, having the following dimensions:--

  Length of the parallelopiped           16-1/2 feet.
  Width                                  10-4/5
  Height                                  7-1/4
  Radius of the cylinder                  5-2/5
  Height or length of semi-cylinder      16-1/2

Whenever the workman has introduced into each pot its charge of ten or
twelve hundred weight of crude sulphur, he closes the charging doors
carefully with their iron plates and cross-bars, and lutes them tight
with loam. He then kindles his fire, and makes the sulphur boil. One of
his first duties (and the least neglect in its discharge may occasion
serious accidents) is to inspect the roof-valves and to clean them, so
that they may play freely and give way to any expulsive force from
within. By means of a cord and chain, connected with a crank attached to
the valves, he can, from time to time, ascertain their state, without
mounting on the roof. It is found proper to work one of the pots a
certain time before fire is applied to the other. The more steadily
vapours of sulphur are seen to issue from the valves, the less
atmospherical air can exist in the chamber, and therefore the less
danger there is of combustion. But if the air be cold, with a sharp
north wind, and if no vapours be escaping, the operator should stand on
his guard, for in such circumstances a serious explosion may ensue.

As soon as both the boilers are in full work the air is expelled, the
fumes cease, and every hazard is at an end. He should bend his whole
attention to the cutting off all communication with the atmosphere,
securing simply the mobility of the valves, and a steady vigour of
distillation. The conclusion of the process is ascertained by
introducing his sounding-rod into the pot, through a small orifice made
for its passage in the wall. A new charge must then be given.

By the above process, well conducted, sulphurs are brought to the most
perfect state of purity that the arts can require; while not above four
parts in the hundred of the sulphur itself are consumed; the crude,
incombustible residuum varying from five to eight parts, according to
the nature of the raw material. But in the sublimation of sulphur, the
frequent combustions inseparable from this operation carry the loss of
weight in flowers to about twenty per cent. See SULPHUR, for a figure of
the subliming apparatus.

The process by fusion, performed at some of the public works in this
country, does not afford a return at all comparable with that of the
above French process, though a much better article is operated upon in
England. After two meltings of rough sulphur (as imported from Sicily or
Italy), eighty-four per cent. is the maximum amount obtained, the
average being probably under eighty; while the product is certainly
inferior in quality to that by distillation.

3. _On the charcoal._--Tender and light woods, capable of affording a
friable and porous charcoal, which burns rapidly away, leaving the
smallest residuum of ashes, and containing therefore the largest
proportion of carbon, ought to be preferred for charring in
gunpowder-works.

After many trials made long ago, black dogwood came to be preferred to
every plant for this purpose; but modern experiments have proved that
many other woods afford an equally suitable charcoal. The woods of black
alder, poplar, lime-tree, horse-chesnut and chesnut-tree, were
carbonized in exactly similar circumstances, and a similar gunpowder was
made with each, which was proved by the same proof-mortar. The following
results were obtained:--

  +------------------+-------+-----+
  |                  |Toises.|Feet.|
  |                  +-------+-----+
  |Poplar--mean range|  113  |  2  |
  |Black alder       |  110  |  4  |
  |Lime              |  110  |  3  |
  |Horse-chesnut     |  110  |  3  |
  |Chesnut-tree      |  109  |     |
  +------------------+-------+-----+

By subsequent experiments confirmatory of the above, it has been further
found that the willow presents the same advantages as the poplar, and
that several shrubs, such as the hazel-nut, the spindle-tree, the
dogberry, the elder-tree, the common sallow, and some others, may be as
advantageously employed. But whichever wood be used, we should always
cut it when full of sap, and never after it is dead; we should choose
branches not more than five or six years old, and strip them carefully,
because the old branches and the bark contain a larger proportion of
earthy constituents. The branches ought not to exceed three-quarters of
an inch in thickness, and the larger ones should be divided lengthwise
into four, so that their pith may be readily burned away.

Wood is commonly carbonized in this country into gunpowder-charcoal in
cast-iron cylinders, with their axes laid horizontally, and built in
brick-work, so that the flame of a furnace may circulate round them. One
end of the cylinder is furnished with a door, for the introduction of
the wood and the removal of the charcoal; the other end terminates in a
pipe, connected with a worm-tub for condensing the pyrolignous acid, and
giving vent to the carburetted hydrogen gases that are disengaged.
Towards the end of the operation, the connexion of the cylinder with the
pyrolignous acid cistern ought to be cut off, and a very free egress
opened for the volatile matter, otherwise the charcoal is apt to get
coated with a fuliginous varnish, and to be even penetrated with
condensable matter, which materially injure its qualities.

In France, the wood is carbonized for the gunpowder works either in
oblong vaulted ovens, or in pits, lined with brick-work or cylinders of
strong sheet-iron. In either case, the heat is derived from the
imperfect combustion of the wood itself to be charred. In general, the
product in charcoal by the latter method is from 16 to 17 parts by
weight from 100 of wood. The pit-process is supposed to afford a more
productive return, and a better article; since the body of wood is much
greater, and the fuliginous vapours are allowed a freer escape. The
surface of a good charcoal should be smooth, but not glistening. See
CHARCOAL.

The charcoal is considered by the scientific manufacturers to be the
ingredient most influential, by its fluctuating qualities, upon the
composition of gunpowder; and, therefore, it ought always to be prepared
under the vigilant and skilful eye of the director of the powder
establishment. If it has been kept for some time, or quenched at first
with water, it is unsuitable for the present purpose. Charcoal
extinguished in a close vessel by exclusion of air, and afterwards
exposed to the atmosphere, absorbs only from three to four per cent. of
moisture, while red-hot charcoal quenched with water may lose by drying
twenty-nine per cent. When the latter sort of charcoal is used for
gunpowder, a deduction of weight must be made for the water present. But
charcoal which has remained long impregnated with moisture, constitutes
a most detrimental ingredient of gunpowder.

4. _On Mixing the Constituents and forming the Powder._

The three ingredients thus prepared are ready for manufacturing into
gunpowder. They are, 1. Separately ground to a fine powder, which is
passed through sorted silk sieves or bolting machines; 2. They are mixed
together in the proper proportions, which we shall afterwards discuss;
3. The composition is then sent to the gunpowder mill, which consists
of two edge-stones of a calcareous kind, turning by means of a
horizontal shaft, on a bed-stone of the same nature; incapable of
affording sparks by collision with steel, as sand-stones would do. On
this bed-stone the composition is spread, and moistened with as small a
quantity of water as will, in conjunction with the weight of the
revolving stones, bring it into a proper body of cake, but by no means
into a pasty state. The line of contact of the rolling edge-stone is
constantly preceded by a hard copper scraper, which goes round with the
wheel, regularly collecting the caking mass, and bringing it into the
track of the stone. From 50 to 60 pounds of cake are usually worked at
one operation, under each millstone. When the mass has been thoroughly
kneaded and incorporated, it is sent to the corning-house, where a
separate mill is employed to form the cake into grains or corns. Here it
is first pressed into a hard firm mass, then broken into small lumps;
after which the corning process is performed, by placing these lumps in
sieves, on each of which is laid a disc or flat cake of lignum vitæ. The
sieves are made of parchment skins, or of copper, perforated with a
multitude of round holes. Several such sieves are fixed in a frame,
which, by proper machinery, has such a motion given to it as to make the
lignum vitæ runner in each sieve move about with considerable velocity,
so as to break down the lumps of the cake, and force its substance
through the holes, in grains of certain sizes. These granular particles
are afterwards separated from the finer dust by proper sieves and
_reels_.

The corned powder must now be hardened, and its rougher angles removed,
by causing it to revolve in a close reel or cask turning rapidly round
its axis. This vessel resembles somewhat a barrel-churn, and is
frequently furnished inside with square bars parallel to its axis, to
aid the polish by attrition.

The gunpowder is finally dried, which is now done generally with a steam
heat, or in some places by transmitting a current of air, previously
heated in another chamber, over canvas shelves, covered with the damp
grains.

5. _On the proportion of the Constituents._

A very extensive suite of experiments, to determine the proportions of
the constituents for producing the best gunpowder, was made at the
Essonne works, by a commission of French chemists and artillerists, in
1794.

Powders in the five following proportions were prepared:--

  +-+------+---------+-----------------------------------+
  | |Nitre.|Charcoal.|Sulphur.                           |
  | +------+---------+-----------------------------------+
  |1|76    |  14     |10     Gunpowder of Bâle.          |
  |2|76    |  12     |12     Gunpowder works of Grenelle.|
  |3|76    |  15     | 9     M. Guyton de Morveau.       |
  |4|77·32 |  13·44  | 9·24  Idem.                       |
  |5|77·5  |  15     | 7·5   M. Riffault.                |
  +-+------+---------+-----------------------------------+

The result of more than two hundred discharges with the proof-mortar
shewed that the first and third gunpowders were the strongest; and the
commissioners in consequence recommended the adoption of the third
proportions. But a few years thereafter it was thought proper to
substitute the first set of proportions, which had been found equal in
force to the other, as they would have a better keeping quality, from
containing a little more sulphur and less charcoal. More recently still,
so strongly impressed have the French government been with the high
value of durability in gunpowders, that they have returned to their
ancient dosage of 75 nitre, 12-1/2 charcoal, and 12-1/2 sulphur. In this
mixture, the proportion of the substance powerfully absorbent of
moisture, viz. the charcoal, is still further reduced, and replaced by
the sulphur, or the conservative ingredient.

If we inquire how the maximum gaseous volume is to be produced from the
chemical reaction of the elements of nitre on charcoal and sulphur, we
shall find it to be by the generation of carbonic oxide and sulphurous
acid, with the disengagement of nitrogen. This will lead us to the
following proportions of these constituents:--

  +------------------------------+-------------+---------+
  |                              |Hydrogen = 1.|Per cent.|
  |                              +-------------+---------+
  |1 prime equivalent of nitre   |     102     |   75·00 |
  |1       ...           sulphur |      16     |   11·77 |
  |3       ...           charcoal|      18     |   13·23 |
  |                              +-------------+---------+
  |                              |     136     |  100·00 |
  +------------------------------+-------------+---------+

The nitre contains five primes of oxygen, of which three, combining with
the three of charcoal, will furnish three of carbonic oxide gas, while
the remaining two will convert the one prime of sulphur into sulphurous
acid gas. The single prime of nitrogen is, therefore, in this view,
disengaged alone.

The gaseous volume, on this supposition, evolved from 136 grains of
gunpowder, equivalent in bulk to 75-1/2 grains of water, or to
three-tenths of a cubic inch, will be, at the atmospheric temperature,
as follows:--

  +---------------+----------------------+
  |               |Grains.  Cubic Inches.|
  |               +----------------------+
  |Carbonic oxide |  42   =   141·6      |
  |Sulphurous acid|  32   =    47·2      |
  |Nitrogen       |  14   =    47·4      |
  |               |           -----      |
  |               |           236·2      |
  +---------------+----------------------+

being an expansion of one volume into 787·3. But as the temperature of
the gases at the instant of their combustive formation must be
incandescent, this volume may be safely estimated at three times the
above amount, or considerably upwards of two thousand times the bulk of
the explosive solid.

But this theoretical account of the gases developed does not well accord
with the experimental products usually assigned, though these are
probably not altogether exact. Much carbonic acid is said to be
disengaged, a large quantity of nitrogen, a little oxide of carbon,
_steam of water_, with _carburetted and sulphuretted hydrogen_. From
experiments to be presently detailed, I am convinced that the amount of
these latter products printed in italics must be very inconsiderable
indeed, and unworthy of ranking in the calculation; for, in fact, fresh
gunpowder does not contain above one per cent. of water, and can
therefore yield little hydrogenated matter. Nor is the hydrogen in the
carbon of any consequence.

It is obvious that the more sulphur is present, the more of the dense
sulphurous acid will be generated, and the less forcibly explosive will
be the gunpowder. This is sufficiently confirmed by the trials at
Essonne, where the gunpowder that contained 12 of sulphur and 12 of
charcoal in 100 parts, did not throw the proof-shell so far as that
which contained only 9 of sulphur and 15 of charcoal. The conservative
property is, however, so capital, especially for the supply of our
remote colonies and for humid climates, that it justifies a slight
sacrifice of strength, which at any rate may be compensated by a small
addition of charge.

_Table of Composition of different Gunpowders._

  +----------------------------------+------+---------+--------+
  |                                  |Nitre.|Charcoal.|Sulphur.|
  |                                  +------+---------+--------+
  |Royal Mills at Waltham Abbey      | 75   |  15     |  10    |
  |France, national establishment    | 75   |  12·5   |  12·5  |
  |French, for sportsmen             | 78   |  12     |  10    |
  |French, for mining                | 65   |  15     |  20    |
  |United States of America          | 75   |  12·5   |  12·5  |
  |Prussia                           | 75   |  13·5   |  11·5  |
  |Russia                            | 73·78|  13·59  |  12·63 |
  |Austria (_musquet_)               | 72   |  17     |  16    |
  |Spain                             | 76·47|  10·78  |  12·75 |
  |Sweden                            | 76   |  15     |   9    |
  |Switzerland (a round powder)      | 76   |  14     |  10    |
  |Chinese                           | 75   |  14·4   |   9·9  |
  |Theoretical proportions (as above)| 75   |  13·23  |  11·77 |
  +----------------------------------+------+---------+--------+

6. _On the Chemical Examination of Gunpowders._

I have treated five different samples: 1. The government powder made at
Waltham Abbey; 2. Glass gunpowder made by John Hall, Dartford; 3. The
treble strong gunpowder of Charles Lawrence and Son; 4. The Dartford
gunpowder of Pigou and Wilks; 5. Superfine treble strong sporting
gunpowder of Curtis and Harvey. The first is coarse-grained, the others
are all of considerable fineness. The specific gravity of each was taken
in oil of turpentine: that of the first and last three was exactly the
same, being 1·80; that of the second was 1·793, all being reduced to
water as unity.

The above density for specimen first, may be calculated thus:--

  75 parts of nitre, specific gravity = 2·000
  15 parts of charcoal, specific gr.  = 1·154
  10 parts of sulphur, specific gr.   = 2·000

The volume of these constituents is 55·5, (the volume of their weight of
water being 100;) by which if their weight 100 be divided, the quotient
is 1·80.

The specific gravity of the first and second of the above powders,
including the interstices of their grains, after being well shaken down
in a phial, is 1·02. This is a curious result, as the size of the grains
is extremely different. That of Pigou and Wilks similarly tried is only
0·99; that of the Battle powder is 1·03; and that of Curtis and Harvey
is nearly 1·05. Gunpowders thus appear to have nearly the same weight as
water, under an equal bulk; so that an imperial gallon will hold from 10
pounds to 10 pounds and a half, as above shown.

The quantities of water which 100 grains of each part with on a steam
bath, and absorb when placed for 24 hours under a moistened receiver
standing in water, are as follows:

  100 grains
          of Waltham Abbey, lose 1·1 by steam heat, gain 0·8 over water.
          of Hall                0·5                     2·2
             Lawrence            1·0                     1·1
             Pigou and Wilks     0·6                     2·2
             Curtis and Harvey   0·9                     1·7

Thus we perceive that the large-grained government powder resists the
hygrometric influence better than the others; among which, however,
Lawrence’s ranks nearly as high. These two are therefore relatively the
best keeping gunpowders of the series.

The process most commonly practised in the analysis of gunpowder seems
to be tolerably exact. The nitre is first separated by hot distilled
water, evaporated and weighed. A minute loss of salt may be counted on,
from its known volatility with boiling water. I have evaporated always
on a steam bath. It is probable that a small portion of the lighter and
looser constituent of gunpowder, the carbon, flies off in the operations
of corning and dusting. Hence, analysis may show a small deficit of
charcoal below the synthetic proportions originally mixed. The residuum
of charcoal and sulphur left on the double filter-paper, being well
dried by the heat of ordinary steam, was estimated, as usual, by the
difference of weight of the inner and outer papers. This residuum was
cleared off into a platina capsule with a tooth-brush, and digested in a
dilute solution of potash at a boiling temperature. Three parts of
potash are fully sufficient to dissolve out one of sulphur. When the
above solution is thrown on a filter, and washed first with a very
dilute solution of potash boiling hot, then with boiling water, and
afterwards dried, the carbon will remain; the weight of which deducted
from that of the mixed powder, will show the amount of sulphur.

I have tried many other modes of estimating the sulphur in gunpowder
more directly, but with little satisfaction in the results. When a
platina capsule, containing gunpowder spread on its bottom, is floated
in oil heated to 400° Fahrenheit, a brisk exhalation of sulphur fumes
rises, but, at the end of several hours, the loss does not amount to
more than one half of the sulphur present.

The mixed residuum of charcoal and sulphur digested in hot oil of
turpentine gives up the sulphur readily; but to separate again the last
portions of the oil from the charcoal or sulphur, requires the aid of
alcohol.

When gunpowder is digested with chlorate of potash and dilute muriatic
acid, at a moderate heat in a retort, the sulphur is acidified; but this
process is disagreeable and slow, and consumes much chlorate. The
resulting sulphuric acid being tested by nitrate of baryta, indicates of
course the quantity of sulphur in the gunpowder. A curious fact occurred
to me in this experiment. After the sulphur and charcoal of the
gunpowder had been quite acidified, I poured some solution of the baryta
salt into the mixture, but no cloud of sulphate ensued. On evaporating
to dryness, however, and redissolving, the nitrate of baryta became
effective, and enabled me to estimate the sulphuric acid generated;
which was of course 10 for every 4 of the sulphur.

The acidification of the sulphur by nitric or nitro-muriatic acid is
likewise a slow and unpleasant operation.

By digesting gunpowder with potash water, so as to convert its sulphur
into a sulphuret, mixing this with nitre in great excess, drying and
igniting, I had hoped to convert the sulphur readily into sulphuric
acid. But on treating the fused mass with dilute nitric acid, more or
less sulphurous acid was exhaled. This occurred even though chlorate of
potash had been mixed with the nitre to aid the oxygenation.

The following are the results of my analyses, conducted by the first
described method:

  +---------------------+------+---------+--------+------------+
  |100 grains afford, of|Nitre.|Charcoal.|Sulphur.|  Water.    |
  +---------------------+------+---------+--------+------------+
  |Waltham Abbey        | 74·5 |  14·4   |  10·0  |1·1         |
  |Hall, Dartford       | 76·2 |  14·0   |   9·0  |0·5 loss 0·3|
  |Pigou and Wilks      | 77·4 |  13·5   |   8·5  |0·6         |
  |Curtis and Harvey    | 76·7 |  12·5   |   9·0  |1·1 loss 0·7|
  |Battle Gunpowder     | 77·0 |  13·5   |   8·0  |0·8 loss 0·7|
  +---------------------+------+---------+--------+------------+

It is probable, for reasons already assigned, that the proportions mixed
by the manufacturers may differ slightly from the above.

The English sporting gunpowders have long been an object of desire and
emulation in France. Their great superiority for fowling pieces over the
product of the French national manufactories, is indisputable. Unwilling
to ascribe this superiority to any genuine cause, M. Vergnaud, captain
of French artillery, in a little work on fulminating powders lately
published, asserts positively, that the English manufacturers of ‘poudre
de chasse’ are guilty of the ‘charlatanisme’ of mixing fulminating
mercury with it. To determine what truth was in this allegation, with
regard at least to the above five celebrated gunpowders, I made the
following experiments:

One grain of fulminating mercury, in crystalline particles, was mixed in
water with 200 grains of the Waltham Abbey gunpowder, and the mixture
was digested over a lamp with a very little muriatic acid. The filtered
liquid gave manifest indications of the corrosive sublimate, into which
fulminating mercury is instantly convertible by muriatic acid; for
copper was quicksilvered by it; potash caused a white cloud in it that
became yellow, and sulphuretted hydrogen gas separated a dirty yellow
white precipitate of bisulphuret of mercury. When the Waltham Abbey
powder was treated alone with dilute muriatic acid, no effect whatever
was produced upon the filtered liquid by the sulphuretted hydrogen gas.

200 grains of each of the above sporting gunpowders were treated
precisely in the same way, but no trace of mercury was obtained by the
severest tests. Since by this process there is no doubt but one 10,000th
part of fulminating mercury could be detected, we may conclude that
Captain Vergnaud’s charge is groundless. The superiority of our sporting
gunpowders is due to the same cause as the superiority of our cotton
fabrics--the care of our manufacturers in selecting the best materials,
and their skill in combining them.

I shall subjoin here some miscellaneous observations upon gunpowder.

In Bengal, mixing is performed by shutting up the ingredients in
barrels, which are turned either by hand or machinery; each containing
50 lbs. weight, or more, of small brass balls. They have ledges on the
inside, which occasion the balls and composition to tumble about and
mingle together, so that the intermixture of the ingredients, after the
process has been gone through, cannot fail to be complete. The operation
is continued two or three hours; and I think it would be an improvement
in Her Majesty’s system of manufacture if this method of mixing were
adopted.

In England two or three pints of water are used for a 42 lb. charge: but
the quantity is variable; both the temperature and the humidity of the
atmosphere influence it.

Bramah’s hydrostatic press, or a very strong wooden press working with a
powerful screw, lever, and windlass, constitutes the description of
mechanism by which density is imparted to gunpowder. The incorporated or
mill-cake powder is laid on the bed or follower of the press, and
separated, at equal distances, by sheets of copper, so that when the
operation is over, it comes out in large thin solid cakes, or strata,
distinguished by the term press-cake. The mill-cake powder at Waltham
Abbey, is submitted to a mean theoretic pressure of 70 to 75 tons per
superficial foot.

Gunpowder should be thoroughly dried, but not by too high a degree of
heat; that of 140° or 150° of Fahrenheit’s thermometer is sufficient. It
appears to be of no consequence whether it be dried by solar heat; by
radiation from red-hot iron, as in the gloom stove; or by a temperature
raised by means of steam. Her Majesty’s gunpowder is dried by the last
two methods. The grain should not be suddenly exposed to the highest
degree of heat, but gradually.

The method of trial best adapted to shew the real inherent strength and
goodness of gunpowder, appears to be an eight or ten-inch iron or brass
mortar, with a truly spherical solid shot, having not more than
one-tenth of an inch windage, and fired with a low charge. The
eight-inch mortar, fired with two ounces of powder, is one of the
established methods of proof at Her Majesty’s works. Gunpowders that
range equally in this mode of trial, may be depended on as being equally
strong.

Another proof is by four drachms of powder laid in a small neat heap, on
a clean, polished, copper plate; which heap is fired at the apex, by a
red-hot iron. The explosion should be sharp and quick; not tardy, nor
lingering; it should produce a sudden concussion in the air, and the
force and power of that concussion ought to be judged of by comparison
with that produced by powder of known good quality. No sparks should fly
off, nor should beads, or globules of alkaline residuum, be left on the
copper. If the copper be left clean, i. e. without gross foulness, and
no lights, i. e. sparks, be seen, the ingredients may be considered to
have been carefully prepared, and the powder to have been well
manipulated, particularly if pressed and glazed; but if the contrary be
the result, there has been a want of skill or of carefulness manifested
in the manufacture.

“Gunpowder,” says Captain Bishop “explodes exactly at the 600° of heat
by Fahrenheit’s thermometer; when gunpowder is exposed to 500° it alters
its nature altogether; not only the whole of the moisture is driven off,
but the saltpetre and sulphur are actually reduced to fusion, both of
which liquefy under the above degree. The powder on cooling, is found to
have changed its colour from a gray to a deep black; the grain has
become extremely indurated, and by exposure even to very moist air, it
then suffers no alteration by imbibing moisture.”

[Illustration: 531]

The mill for grinding the gunpowder cake may be understood from the
following representation: (_fig._ 531.) _p_, is the water wheel, which
may drive several pairs of stones; _q_, _q_, two vertical bevel wheels,
fixed upon the axis of the great wheel; _r_, _r_, two horizontal bevel
wheels working in _q_, _q_, and turning the shafts _s_, _s_; _t_, _t_,
two horizontal spur wheels fixed to the upper part of the vertical
shafts, and driving the large wheels _u_, _u_. To the shafts of these
latter wheels are fixed the runners _v_, _v_, which traverse upon the
bed stone _w_, _w_; _x_, _x_, are the curbs surrounding the bed stone to
prevent the powder from falling off; _o_ is the scraper. Mill A
represents a view, and mill B a section of the bed stone and curb.


GYPSUM, _Sulphate of Lime_, _Alabaster_, _or Paris Plaster_. This
substance is found in three geological positions in the crust of the
earth; among transition rocks; in the red marl formation; and above the
chalk, in the tertiary beds.

1. The alpine gypsums are ranged by M. Brochant among the transition
class, and are characterized by the presence of anthracite or stone
coal; some of them are white and pure, others gray or yellowish, and
mixed with mica, talc, steatite, black oxide of iron, pyrites, compact
carbonate of lime, sulphur, and common salt. Examples of such localities
are found in the gypsum of _Val-Canaria_ at the foot of Saint Gothard,
that of Brigg in the upper Valais; of the Grilla in the valley of
Chamouni, and of Saint Gervais-les-Bains, near Sallenches in Savoy.

2. The secondary gypsum, or that of the salt mine districts, belongs to
the _red ground_, immediately beneath the lias in the order of
stratification, and therefore a rock relatively antient. Near Northwick,
the red marl beds above the great deposit of rock salt, are irregularly
intersected with gypsum, in numerous laminæ or plates. At Newbiggin in
Cumberland, the gypsum lies in red argillaceous marl, between two strata
of sandstone; and a mile south of Whitehaven, the subterraneous workings
for the alabaster extend 30 yards in a direct line; with two or three
lateral branches extending about 10 yards, at whose extremities are
large spaces where the gypsum is blasted with gunpowder. It is generally
compact, forming a regular and conformable bed, with crystals of
selenite (crystallized gypsum) in drusy cavities. Gypsum occurs in the
red marl in the isle of Axholme, and various other places in
Nottinghamshire. In Derbyshire some considerable deposits have been
found in the same red sandstone, several of which are mined, as at
Chellaston hill, which would exhibit a naked and water-worn rock of
gypsum, were it not for a covering of alluvial clay. It appears in
general to present itself chiefly in particular patches, occasioning a
sudden rise, or an insulated hill, by the additional thickness which it
gives to the stratum of the _red ground_ in these places. The principal
demand for the pure white gypsum, or that faintly streaked with red, is
by the potters in Staffordshire, who form their moulds with the calcined
powder which it affords; only particularly fine blocks are selected for
making alabaster ornaments on the turning lathe. In one of the salt pits
near Droitwich, the strata sunk through, were, vegetable mould, 3 feet;
red marl, 35 feet; gypsum, 40 feet; a river of brine, 22 inches; gypsum,
75 feet; a rock of salt, bored into only 5 feet, but probably extending
much deeper. On the Welsh side of the Bristol channel, gypsum occurs in
the red marl cliffs of _Glamorganshire_, from Pennarth to Lavernock. No
organic remains or metallic minerals have hitherto been found in the
gypsum of this formation.

3. The most interesting gypsums in a general point of view, are
certainly the tertiary, or those of the plains, or hills of
comparatively modern formation. They are characterized, by the presence
of fossil bones of extinct animals, both _mammifera_ and birds, by
shells, and a large proportion of carbonate of lime, which gives them
the property of effervescing with acids, and the title of limestone
gypsums. Such are the gypsums of the environs of Paris, as at the
heights of Montmartre, which contain crystallized sulphate of lime in
many forms, but most commonly the lenticular and lance-shaped.

Sulphate of lime occurs either as a dense compound without water, and is
called _anhydrite_ from that circumstance; or with combined water, which
is its most ordinary state. Of the latter there are 6 sub-species;
sparry gypsum or selenite in a variety of crystalline forms; the
foliated granular; the compact; the fibrous; the scaly foliated; the
earthy.

The prevailing colour is white, with various shades of gray, blue, red,
and yellow. More or less translucent. Soft, sectile, yielding to the
nail. Specific gravity 2·2. Water dissolves about one five-hundredth
part of its weight of gypsum, and acquires the quality of hardness, with
the characteristic selenitic taste. When exposed on red hot coals, it
decrepitates, becomes white, and splits into a great many brittle
plates. At the heat of a baker’s oven, or about 400° Fahr., the combined
water of gypsum escapes with a species of ebullition. At a higher
temperature the particles get indurated. When rightly calcined and
pulverized, gypsum is mixed with water to the consistence of cream, and
poured into moulds by the manufacturers of stucco ornaments and statues.
A species of rapid crystallization ensues, and the thin paste soon
acquires a solid consistence, which is increased by drying the figure in
proper stoves. During the consolidation of the plaster, its volume
expands into the finest lines of the mould, so as to give a sharp and
faithful impression.

The plaster stone of the Paris basin contains about 12 _per cent._ of
carbonate of lime. This body, ground and mixed with water, forms an
adhesive mortar much used in building, as it fixes very speedily. Works
executed with pure gypsum never become so hard as those made with the
calcareous kind; and hence it might be proper to add a certain portion
of white slaked lime to our calcined gypsum, in order to give the stucco
this valuable property. Coloured stuccos of great solidity are made by
adding to a clear solution of glue, any desired colouring tincture, and
mixing-in the proper quantity of the calcined calcareous gypsum.

The compact, fine-grained gypseous alabaster is often cut into various
ornamental figures, such as vases, statuary groups, &c., which take a
high polish and look beautiful, but from their softness are easily
injured, and require to be kept enclosed within a glass shade.

In America and France, the virtues of gypsum in fertilizing land have
been highly extolled, but they have not been realized in the trials made
in this kingdom.

Pure gypsum consists of lime 28; sulphuric acid 40; water 18; which are
the respective weights of its prime equivalent parts.

M. Gay Lussac, in a short notice, in the _Annales de Chimie_ for April
1829, on the setting of gypsum, says that the purest plasters are those
that harden least, and that the addition of lime is of no use towards
promoting their solidity, nor can the heat proper for boiling gypsum
ever expel the carbonic acid gas from the calcareous carbonate present
in the gypsum of Montmartre. He conceives that a _hard_ plaster-stone
having lost its water, will resume more solidity in returning to its
first state, than a plaster-stone naturally tender or soft; and that it
is the primitive molecular arrangement which is regenerated. See
ALABASTER.




H.


HADE; signifies among English miners, the inclination, or deviation from
the vertical, of any mineral vein.


HAIR; (_Cheveu_, _Crin_, Fr.; _Haar_, Germ.) is of all animal products,
the one least liable to spontaneous change. It can be dissolved in water
only at a temperature somewhat above 230° F., in a Papin’s digester, but
it appears to be partially decomposed by this heat, since some
sulphuretted hydrogen is disengaged. By dry distillation, hair gives off
several sulphuretted gases, while the residuum contains sulphate of
lime, common salt, much silica, with some oxide of iron and manganese.
It is a remarkable fact that fair hair affords magnesia, instead of
these latter two oxides. Horse-hair yields about 12 per cent. of
phosphate of lime.

Hairs are tubular, their cavities being filled with a fat oil, having
the same colour with themselves. Hair plunged in chlorine gas, is
immediately decomposed and converted into a viscid mass; but when
immersed in weak aqueous chlorine, it undergoes no change, except a
little bleaching. The application of nitrate of mercury to hairy skins
in the process of _secrétage_, is explained under PELTRY.

For the dyeing of horse-hair, see the next article.

Living hairs are rendered black by applying to them for a short time, a
paste made by mixing litharge, slaked lime, and bicarbonate of potash,
in various proportions, according to the shade of colour desired.

We have no recent analysis of hair. Vauquelin found nine different
substances in black hair; in red hair, a red oil instead of a
greenish-black one.

The salts of mercury, lead, bismuth, as well as their oxides, blacken
hair, or make it of a dark violet, by the formation, most probably, of
metallic sulphurets.

Hair as an object of manufactures is of two kinds, the _curly_ and the
_straight_. The former, which is short, is spun into a cord, and boiled
in this state, to give it the tortuous springy form. The long straight
hair is woven into cloth for sieves, and also for ornamental purposes,
as in the damask-hair cloth of chair bottoms. For this purpose the hair
may be dyed in the following way.

Forty pounds of tail hair about 26 inches long are steeped in lime water
during twelve hours. Then a bath is made with a decoction of 20 pounds
of logwood, kept boiling for three hours, after which time the fire is
withdrawn from the boiler, and ten ounces of copperas are introduced,
stirred about, and the hair is immersed, having been washed from the
lime in river water. The hair should remain in this cooling bath for 24
hours, when the operation will be finished. For other colours, see the
respective dyes.

[Illustration: 532]

The looms for weaving hair differ from the common ones, only in the
templet and the shuttle. Two templets of iron must be used to keep the
stuff equably, but lightly stretched. These templets, of which one is
represented in _fig._ 532., are constructed in the shape of flat
pincers; the jaws C C being furnished with teeth inside. A screw D,
binds the jaws together, and hinders the selvage from going inwards.
Upon the side cross beam of the loom, seen in section at I, a bolt is
fixed which carries a nut F at its end, into which a screwed iron rod E
enters, on one of whose ends is the handle B. The other extremity of the
screw E is adapted by a washer and pin to the back of the pincers at the
point H, so that by turning the handle to the right or the left, we draw
onwards or push backwards the pincers and the stuff at pleasure. The
warp of the web is made of black linen yarn. The weft is of hair, and it
is thrown with a long hooked shuttle; or a long rod, having a catch hook
at its end. The length of this shuttle is about 3 feet; its breadth half
an inch, and its thickness one sixth. It is made of box-wood. The reed
is of polished steel; the thread warps are conducted through it in the
usual way. The workman passes this shuttle between the hairs of the warp
with one hand, when the shed or shuttle way is opened by the treddles; a
child placed on one side of the loom presents a hair to the weaver near
the selvage, who catches it with the hook of his shuttle, and by drawing
it out passes it through the warp. The hairs are placed in a bundle on
the side where the child stands, in a chest filled with water to keep
them moist, for otherwise they would not have the suppleness requisite
to form a web. Each time that a hair is thrown across, the batten is
driven home twice. The warp is dressed with paste in the usual way. The
hair cloth after it is woven, is hot calendered to give it lustre.


HAIR PENCILS OR BRUSHES for painting. Two sorts are made; those with
coarse hair, as that of the swine, the wild boar, the dog, &c., which
are attached usually to short wooden rods as handles; these are commonly
called _brushes_; and hair pencils properly so called, which are
composed of very fine hairs, as of the minever, the marten, the badger,
the polecat, &c. These are mounted in a quill when they are small or of
moderate size, but when larger than a quill, they are mounted in
white-iron tubes.

The most essential quality of a good pencil is to form a fine point, so
that all the hairs without exception may be united when they are
moistened by laying them upon the tongue, or drawing them through the
lips. When hairs present the form of an elongated cone in a pencil,
their point only can be used. The whole difficulty consists after the
hairs are cleansed, in arranging them together so that all their points
may lie in the same horizontal plane. We must wash the tails of the
animals whose hairs are to be used, by scouring them in a solution of
alum till they be quite free from grease, and then steeping them for 24
hours in luke-warm water. We next squeeze out the water by pressing them
strongly from the root to the tip, in order to lay the hairs as smooth
as possible. They are to be dried with pressure in linen cloths, combed
in the longitudinal direction, with a very fine-toothed comb, finally
wrapped up in fine linen, and dried. When perfectly dry, the hairs are
seized with pincers, cut across close to the skin, and arranged in
separate heaps, according to their respective lengths.

Each of these little heaps is placed separately, one after the other, in
small tin pans with flat bottoms, with the tips of the hair upwards. On
striking the bottom of the pan slightly upon a table, the hairs get
arranged parallel to each other, and their delicate points rise more or
less according to their lengths. The longer ones are to be picked out
and made into so many separate parcels, whereby each parcel may be
composed of equally long hairs. The perfection of the pencil depends
upon this equality; the tapering point being produced simply by the
attenuation of the tips.

A pinch of one of these parcels is then taken, of a thickness
corresponding to the intended size of the pencil; it is set in a little
tin pan, with its tips undermost, and is shaken by striking the pan on
the table as before. The root end of the hairs being tied by the
fisherman’s or seaman’s knot, with a fine thread, it is taken out of the
pan, and then hooped with stronger thread or twine; the knots being
drawn very tight by means of two little sticks. The distance from the
tips at which these ligatures are placed, is of course relative to the
nature of the hair, and the desired length of the pencil. The base of
the pencil must be trimmed flat with a pair of scissors.

Nothing now remains to be done but to mount the pencils in quill or
tin-plate tubes as above described. The quills are those of swans,
geese, ducks, lapwings, pigeons, or larks, according to the size of the
pencil. They are steeped during 24 hours in water, to swell and soften
them, and to prevent the chance of their splitting when the hair brush
is pressed into them. The brush of hair is introduced by its tips into
the large end of the cut quill, having previously drawn them to a point
with the lips, when it is pushed forwards with a wire of the same
diameter, till it comes out at the other and narrower end of the quill.

The smaller the pencils, the finer ought the hairs to be. In this
respect, the manufacture requires much delicacy of tact and experience.
It is said, that there are only four first-rate hands among all the
dexterous pencil-makers of Paris, and that these are principally women.


HALOGENE; is a term employed by Berzelius to designate those substances
which form compounds of a saline nature, by their union with metals;
such are _Bromine_, _Chlorine_, _Cyanogene_, _Fluorine_, _Iodine_.
_Haloid_ is his name of the salt thereby formed.


HANDSPIKE, is a strong wooden bar, used as a lever to move the windlass
and capstan in heaving up the anchor, or raising any heavy weights on
board a ship. The handle is smooth, round, and somewhat taper; the other
end is squared to fit the holes in the head of the capstan or barrel of
the windlass.


HARDNESS (_Dureté_, Fr.; _Härte_, _Festigkeit_, Germ.); is that
modification of cohesive attraction which enables bodies to resist any
effort made to abrade their surfaces. Its relative intensity is measured
by the power they possess of cutting or scratching other substances. The
following table exhibits pretty nearly the successive hardnesses of the
several bodies in the list:--

  +---------------------+---------+---------+
  |    Substances.      |Hardness.|Sp. Grav.|
  +---------------------+---------+---------+
  |Diamond from Ormus   |   20    |   3·7   |
  |Pink diamond         |   19    |   3·4   |
  |Bluish diamond       |   19    |   3·3   |
  |Yellowish diamond    |   19    |   3·3   |
  |Cubic diamond        |   18    |   3·2   |
  |Ruby                 |   17    |   4·2   |
  |Pale ruby from Brazil|   16    |   3·5   |
  |Deep blue sapphire   |   16    |   3·8   |
  |Ditto, paler         |   17    |   3·8   |
  |Topaz                |   15    |   4·2   |
  |Whitish topaz        |   14    |   3·5   |
  |Ruby spinell         |   13    |   3·4   |
  |Bohemian topaz       |   11    |   2·8   |
  |Emerald              |   12    |   2·8   |
  |Garnet               |   12    |   4·4   |
  |Agate                |   12    |   2·6   |
  |Onyx                 |   12    |   2·6   |
  |Sardonyx             |   12    |   2·6   |
  |Occidental amethyst  |   11    |   2·7   |
  |Crystal              |   11    |   2·6   |
  |Cornelian            |   11    |   2·7   |
  |Green jasper         |   11    |   2·7   |
  |Reddish yellow do.   |    9    |   2·6   |
  |Schoerl              |   10    |   3·6   |
  |Tourmaline           |   10    |   3·0   |
  |Quartz               |   10    |   2·7   |
  |Opal                 |   10    |   2·6   |
  |Chrysolite           |   10    |   3·7   |
  |Zeolite              |    8    |   2·1   |
  |Fluor                |    7    |   3·5   |
  |Calcareous spar      |    6    |   2·7   |
  |Gypsum               |    5    |   2·3   |
  |Chalk                |    3    |   2·7   |
  +---------------------+---------+---------+


HARTSHORN, SPIRIT OF; is the old name for water of ammonia.


HATCHING OF CHICKENS; see INCUBATION, ARTIFICIAL.


HAT MANUFACTURE. (_L’art de Chapelier_, Fr.; _Hutmacherkunst_, Germ.)
Hat is the name of a piece of dress worn upon the head by both sexes,
but principally by the men, and seems to have been first introduced as a
distinction among the ecclesiastics in the 12th century, though it was
not till the year 1400 that it was generally adopted by respectable
laymen.

As the art of making common hats does not involve the description of any
curious machinery, or any interesting processes, we shall not enter into
very minute details upon the subject. It will be sufficient to convey to
the reader a general idea of the methods employed in this manufacture.

The materials used in making stuff hats are the furs of hares and
rabbits freed from the long hair, together with wool and beaver. The
beaver is reserved for the finer hats. The fur is first laid upon a
hurdle made of wood or wire, with longitudinal openings; and the
operator, by means of an instrument called the bow, (which is a piece of
elastic ash, six or seven feet long, with a catgut stretched between its
two extremities, and made to vibrate by a bowstick,) causes the
vibrating string to strike and play upon the fur, so as to scatter the
fibres in all directions, while the dust and filth descend through the
grids of the hurdle.

After the fur is thus driven by the bow from the one end of the hurdle
to the other, it forms a mass called a _bat_, which is only half the
quantity sufficient for a hat. The bat or _capade_ thus formed is
rendered compact by pressing it down with the _hardening skin_, (a piece
of half-tanned leather,) and the union of the fibres is increased by
covering them with a cloth, while the workman presses them together
repeatedly with his hands. The cloth being taken off, a piece of paper,
with its corners doubled in, so as to give it a triangular outline, is
laid above the bat. The opposite edges of the bat are then folded over
the paper, and being brought together and pressed again with the hands,
they form a conical cap. This cap is next laid upon another bat, ready
hardened, so that the joined edges of the first bat rest upon the new
one. This new bat is folded over the other, and its edges joined by
pressure as before; so that the joining of the first conical cap is
opposite to that of the second. This compound bat is now wrought with
the hands for a considerable time upon the hurdle between folds of linen
cloth, being occasionally sprinkled with clear water, till the hat is
basoned or rendered tolerably firm.

[Illustration: 533]

The cap is now taken to a wooden receiver, like a very flat mill-hopper,
consisting of eight wooden planes, sloping gently to the centre, which
contains a kettle filled with water acidulated with sulphuric acid. The
technical name of this vessel is the _battery_. It consists of a kettle
A; and of the planks, B C, which are sloping planes, usually eight in
number, one being allotted to each workman. The half of each plank next
the kettle is made of lead, the upper half of mahogany. In this liquor
the hat is occasionally dipped, and wrought by the hands, or sometimes
with a roller, upon the sloping planks. It is thus fulled or thickened
during four or five hours; the knots or hard substances are picked out
by the workman, and fresh felt is added by means of a wet brush to those
parts that require it. The beaver is applied at the end of this
operation. In the manufacture of beaver hats, the grounds of beer are
added to the liquor in the kettle.

_Stopping_, or thickening the thin spots, seen by looking through the
body, is performed by daubing on additional stuff with successive
applications of the hot acidulous liquor from a brush dipped into the
kettle, until the body be sufficiently shrunk and made uniform. After
drying, it is stiffened with varnish composition rubbed in with a brush;
the inside surface being more copiously imbued with it than the outer;
while the brim is peculiarly charged with the stiffening.

When once more dried, the body is ready to be _covered_, which is done
at the _battery_. The first cover of beaver or napping, which has been
previously _bowed_, is strewed equably over the body, and patted on with
a brush moistened with the hot liquor, until it gets incorporated; the
cut ends towards the root, being the points which spontaneously intrude.
The body is now put into a coarse hair cloth, then dipped and rolled in
the hot liquor, until the root ends of the beaver are thoroughly worked
in. This is technically called rolling off, or _roughing_. A strip for
the brim, round the edge of the inside, is treated in the same way;
whereby every thing is ready for the second cover (of beaver), which is
incorporated in like manner; the rolling, &c. being continued, till a
uniform, close, and well-felted hood is formed.

The hat is now ready to receive its proper shape. For this purpose the
workman turns up the edge or brim to the depth of about 1-1/2 inch, and
then returns the point of the cone back again through the axis of the
cap, so as to produce another inner fold of the same depth. A third fold
is produced by returning the point of the cone, and so on till the point
resembles a flat circular piece having a number of concentric folds. In
this state it is laid upon the plank, and wetted with the liquor. The
workman pulls out the point with his fingers, and presses it down with
his hand, turning it at the same time round on its centre upon the
plank, till a flat portion, equal to the crown of the hat, is rubbed
out. This flat crown is now placed upon a block, and, by pressing a
string called a _commander_, down the sides of the block, he forces the
parts adjacent to the crown, to assume a cylindrical figure. The brim
now appears like a puckered appendage round the cylindrical cone; but
the proper figure is next given to it, by working and rubbing it. The
body is rendered waterproof and stiff by being imbued with a varnish
composed of shellac, sandarach, mastic, and other resins dissolved in
alcohol or naphtha.

The hat being dried, its nap is raised or loosened with a wire brush or
card, and sometimes it is previously pounced or rubbed with pumice, to
take off the coarser parts, and afterwards rubbed over with seal-skin.
The hat is now tied with pack-thread upon its block, and is afterwards
dyed. See HAT-DYEING, _infra_.

The dyed hats are now removed to the stiffening shop. Beer grounds are
next applied on the inside of the crown, for the purpose of preventing
the glue from coming through; and when the beer grounds are dried, glue,
(gum Senegal is sometimes used,) a little thinner than that used by
carpenters, is laid with a brush on the inside of the crown, and the
lower surface of the brim.

The hat is then softened by exposure to steam, on the steaming basin,
and is brushed and ironed till it receives the proper gloss. It is
lastly cut round at the brim by a knife fixed at the end of a gauge,
which rests against the crown. The brim, however, is not cut entirely
through, but is torn off so as to leave an edging of beaver round the
external rim of the hat. The crown being tied up in a gauze paper, which
is neatly ironed down, is then ready for the last operations of lining
and binding.

The furs and wools of which hats are manufactured contain in their early
stage of preparation, _hemps_ and _hairs_, which must be removed in
order to produce a material for the better description of hats. This
separation is effected by a sort of winnowing machine, which wafts away
the finer and lighter parts of the furs and wools from the coarser.
Messrs. Parker and Harris obtained a patent in 1822 for the invention
and use of such an apparatus, whose structure and functions may be
perfectly understood, from its analogy to the blowing and scutching
machine of the cotton manufacture; to which I therefore refer my
readers.

I shall now proceed to describe some of the recent improvements proposed
in the manufacture of hats, but their introduction is scarcely possible,
on account of the perfectly organized combination which exists among
journeymen hatters throughout the kingdom, by which the masters are held
in a state of complete servitude, having no power to take a single
apprentice into their works beyond the number specified by the _Union_,
nor any sort of machine which is likely to supersede hand labour in any
remarkable degree. Hence the hat trade is, generally speaking,
unproductive to the capitalist, and incapable of receiving any
considerable development. The public of a free country like this, ought
to counteract this disgraceful state of things, by renouncing the wear
of stuff hats, a branch of the business entirely under the controul of
this despotic _Union_, and betake themselves to the use of silk hats,
which, from recent improvements in their fabric and dyeing, are not a
whit inferior to the beaver hats, in comfort, appearance, or durability,
while they may be had of the best quality for one-fourth part of their
price.

[Illustration: 534 535]

The annexed figures represent Mr. Ollerenshaw’s machine, now generally
employed for ironing hats. _Fig._ 534. is the frame-work or standard
upon which three of these lathes are mounted, as A, B, C. The lathe A is
intended to be employed when the crown of the hat is to be ironed. The
lathe B, when the flat top, and the upper side of the brim is ironed,
and lathe C, when its under side is ironed; motion being given to the
whole by means of a band passing from any first mover (as a
steam-engine, water-wheel, &c.) to the drum on the main shaft _a a_.
From this drum a strap passes over the rigger _b_, which actuates the
axle of the lathe A. On to this lathe a sort of chuck is screwed, and to
the chuck the block _c_ is made fast by screws, bolts, or pins. This
block is represented in section, in order to shew the manner in which it
is made, of several pieces held fast by the centre wedge-piece, as seen
at _fig._ 535.

[Illustration: 536]

The hat-block being made to turn round with the chuck, at the rate of
about twenty turns per minute, but in the opposite direction to the
revolution of an ordinary turning lathe, the workman applies his hot
iron to the surface of the hat, and thereby smooths it, giving a
beautiful glossy appearance to the beaver; he then applies a plush
cushion, and rubs round the surface of the hat while it is still
revolving. The hat, with its block, is now removed to the lath B, where
it is placed upon the chuck _d_, and made to turn in a horizontal
direction, at the rate of about twenty revolutions per minute, for the
purpose of ironing the flat-top of the crown. This lathe B moves upon an
upright shaft _e_, and is actuated by a twisted band passing from the
main shaft, round the rigger _f_. In order to iron the upper surface of
the brim, the block _c_ is removed from the lathe, and taken out of the
hat, when the block _fig._ 536. is mounted upon the chuck _d_, and made
to turn under the hand of the workman, as before.

[Illustration: 537]

The hat is now to be removed to the lathe C, where it is introduced in
an inverted position, between the arms _g g_ supporting the rim _h h_,
the top surface of which is shewn at _fig._ 537. The spindle _i_ of the
lathe turns by similar means to the last, but slower; only ten turns per
minute will be sufficient. The workman now smooths the under side of the
brim, by drawing the iron across it, that is from the centre outwards.
The hat is then carefully examined, and all the burs and coarse hairs
picked out, after which the smoothing process is performed as before,
and the dressing of the hat is complete.

Messrs. Gillman and Wilson, of Manchester, obtained a patent, in 1823,
for a peculiar kind of fabric to be made of cotton, or a mixture of
cotton and silk, for the covering of hats and bonnets, in imitation of
beaver. The foundation of the hat may be of felt, hemp, wool, which is
to be covered, by the patent fabric. This debased article does not seem
to have got into use; cotton, from its want of the felting property and
inelasticity, being very ill-adapted for making hat-stuff.

A more ingenious invention of John Gibson, hatter, in Glasgow,
consisting of an elastic fabric of whalebone, was made the subject of a
patent, in June, 1824. The whalebone, being separated into threads no
larger than hay stalks, is to be boiled in some alkaline liquid for
removing the oil from it, and rendering it more elastic. The longest
threads are to be employed for warp, the shorter for weft; and are to be
woven in a hair-cloth loom. This fabric is to be passed between rollers,
after which it is fit to be cut out into forms for making hats and
bonnets, to be sewed together at the joints, and stiffened with a
preparation of resinous varnishes, to prevent its being acted upon by
perspiration or rain. A very considerable improvement in the lightness
and elasticity of silk hats has been the result of this invention.

The foundation of men’s hats, upon whose outside the beaver, down, or
other fine fur is laid to produce a nap, is, as I have described,
usually made of wool felted together by hand, and formed first into
conical caps, which are afterwards stretched and moulded upon blocks to
the desired shape. Mr. Borradaile, of Bucklersbury, obtained a patent in
November 1825, for a machine, invented by a foreigner, for setting up
hat bodies, which seems to be ingeniously contrived; but I shall decline
describing it, as it has probably not been suffered by the _Union_ to
come into practical operation, and as I shall presently give the details
of another later invention for the same purpose.

Silk hats, for several years after they were manufactured, were liable
to two objections; first, the body or shell over which the silk covering
is laid, was, from its hardness, apt to hurt the head; second, the edge
of the crown being much exposed to blows, the silk nap soon got abraded,
so as to lay bare the cotton foundation, which is not capable of taking
so fine a black die as the silk; whence the hat assumed a shabby
appearance. Messrs. Mayhew and White, of London, hat-manufacturers,
proposed in their patent of February, 1826, to remedy these defects, by
making the hat body of stuff or wool, and relieving the stiffness of the
inner part round the brim, by attaching a coating of beaver upon the
under side of the brim, so as to render the hat pliable. Round the edge
of the tip or crown, a quantity of what is called stop wool is to be
attached by the ordinary operation of bowing, which will render the edge
soft and elastic. The hat is to be afterwards dyed of a good black
colour, both outside and inside; and being then properly stiffened and
blocked, is ready for the covering of silk.

The plush employed for covering silk hats, is a raised nap or pile woven
usually upon a cotton foundation; and the cotton, being incapable of
receiving the same brilliant black dye as the silk, renders the hat apt
to turn brown whenever the silk nap is partially worn off. The patentees
proposed to counteract this evil, by making the foundation of the plush
entirely of silk. To these two improvements, now pretty generally
introduced, the present excellence of the silk hats, may be, in a good
measure, ascribed.

The apparatus above alluded to, for making the foundations of hats by
the aid of mechanism, was rendered the subject of a patent, by Mr.
Williams, in September, 1826; but I fear it has never obtained a
footing, nor even a fair trial in our manufactures, on account of the
hostility of the operatives to all labour-saving machines.

[Illustration: 538]

_Fig._ 538. is a side view of the carding engine, with a horizontal or
plan view of the lower part of the carding machine, shewing the
operative parts of the winding apparatus, as connected to the carding
engine. The doffer cylinder is covered with fillets of wire cards, such
as are usually employed in carding engines, and these fillets are
divided into two, three, or more spaces extending round the periphery of
the cylinder, the object of which division is to separate the sliver
into two, three, or more breadths, which are to be conducted to, and
wound upon distinct blocks, for making so many separate hats or caps.

The principal cylinder of the carding engine, is made to revolve by a
rigger upon its axle, actuated by a band from any first mover as usual,
and the subordinate rollers or cylinders belonging to the carding
engine, are all turned by pullies, and bands, and geer, as in the
ordinary construction.

The wool or other material is supplied to the feeding cloth, and carried
through the engine to the doffer cylinder, as in other carding engines;
the doffer comb is actuated by a revolving crank in the common way, and
by means of it the slivers are taken from the doffer cylinder, and
thence received on to the surfaces of the blocks _e e_. These blocks, of
which two only are shewn to prevent confusion, are mounted upon axles,
supported by suitable bearings in a carriage _f f_, and are made to
revolve by means of a band _g g_, leading from a pulley on the axle of a
conical drum beneath. The band _g_ passes over a pulley _h_, affixed to
the axle of one of the blocks, while another pulley _i_, upon the same
axle, gives motion, by means of a band, to as many other blocks as are
adapted to the machine.

As it is necessary in winding the slivers on to the blocks, to cross
them in different directions, and also to pass the sliver over the
hemispherical ends of the blocks, in order that the wool or other
material may be uniformly spread over the surface in forming the cap or
hood for the shell or foundation of the intended hat, the carriage _f_,
with the blocks, is made to traverse to and fro in lateral directions
upon rollers at each end.

This alternating motion of the carriage is caused by a horizontal lever
_l l_, (seen in the horizontal view _fig._ 538.) moving upon a fulcrum
pin at _m_, which lever is attached to the carriage at one extremity
_n_, and at the other end has a weighted cord which draws the side of
this lever against a cam wheel _o_. This cam is made to revolve by means
of a band and pulley, which turns the shaft and endless screw _q_, and
this endless screw taking into a toothed wheel _r_, on the axle of the
cam _o_, causes the cam to revolve, the periphery of which cam running
against a friction roller on the side of the lever _l_, causes the lever
to vibrate, and the carriage _f f_, attached to it, to traverse to and
fro upon the supporting rollers, as described. By these means the
slivers are laid in oblique directions, (varying as the carriage
traverses,) over the surface of the blocks.

The blocks being conically formed, or of other irregular figures, it is
necessary, in order to wind the slivers with uniform tension, to vary
their speed according to the diameter of that part of the block which is
receiving the sliver. This is effected by giving different velocities to
the pulley on the axle of the conical drum _s_, corresponding with _e_.
There is a similar conical drum _t_, placed in a reverse position in the
lower part of the frame, which is actuated by a band from any
convenient part of the machine passing over a pulley _u_, upon the axle
of _t_. From the drum _t_, to the drum _s_, there is a band _v_, which
is made to slide along the drums by the guidance of two rollers at the
end of the lever _l_.

It will now be seen that when the larger diameter of the cam wheel _o_
forces the lever outwards, the band _v_ will be guided on to the smaller
part of the conical drum _t_, and the larger part of _s_, consequently
the drum _s_ will at this time receive its slowest motion, and the band
_g_ will turn the blocks slower also; the reverse end of the lever _l_,
having by the same movement, slidden the carriage into that position
which causes the slivers to wind upon the larger diameter of the blocks.

When the smaller diameter of the cam is acting against the side of the
lever, the weighted cord draws the end of the lever to the opposite
side, and the band _v_ will be guided on to the larger part of the cord
_t_, and the smaller part of the cone _s_; consequently, the quicker
movement of the band _g_ will now cause the blocks _e e_ to revolve with
a corresponding speed. The carriage _f_ will also be moved upon its
rollers, to the reverse side, and the sliver of wool or other material
be now wound upon the smaller parts and ends of the blocks, at which
time the quicker rotation of the blocks is required. It may be here
observed, that the cam wheel _o_ should be differently formed according
to the different shaped blocks employed, so as to produce the requisite
movements of the lever and carriage suited thereto.

It only remains to state, that there are two heavy conical rollers _w
w_, bearing upon the peripheries of the blocks _e e_, which turn loosely
upon their axles by the friction of contact, for the purpose of pressing
the slivers of wool or other material on the blocks as it comes from the
doffer cylinder of the carding engine, and when the blocks have been
coated with a sufficient quantity of the sliver, the smaller end of the
pressing rollers is to be raised, while the cap is withdrawn from the
block. The process being continued as before, the formations of other
bodies or caps is effected in the manner above described.

[Illustration: 539]

After the caps or bodies of hats, &c. are formed in the above described
machine, they are folded in wet cloths, and placed upon heated plates,
where they are rolled under pressure, for the purpose of being hardened.
_Fig._ 539. represents the front of three furnaces _a a a_, the tops of
which are covered with iron plates _b b b_. Upon these plates, which are
heated by the furnace below, or by steam, the bodies wrapped in the wet
cloths _c c c_, are placed, and pressed upon by the flaps or covers _d d
d_, sliding upon guide rods, to which flaps a traversing motion is
given, by means of chains attached to an alternating bar _e e_. This bar
is moved by a rotatory crank _f_, which has its motion by pulleys from
any actuating power. When any one of the flaps is turned up to remove
the bodies from beneath, the chains hang loosely, and the flap remains
stationary.

These caps or hat bodies, after having been hardened in the manner above
described, may be felted in the usual way by hand, or they are felted in
a fulling mill, by the usual process employed for milling cloths, except
that the hat bodies are occasionally taken out of the fulling mill, and
passed between rollers, for the purpose of rendering the felt more
perfect.

Mr. Carey, of Basford, obtained a patent in October, 1834, for an
invention of certain machinery to be employed in the manufacture of
hats, which is ingenious and seems to be worthy of notice in this place.
It consists in the adaptation of a system of rollers, forming a machine,
by means of which the operation of roughing or plaiting of hats may be
performed; that is, the beaver or other fur may be made to attach
itself, and work into the felt or hat body, without the necessity of the
ordinary manual operations.

[Illustration: 540 543]

The accompanying drawings represent the machine in several views, for
the purpose of showing the construction of all its parts. _Fig._ 540. is
a front elevation of the machine; _fig._ 541. is a side elevation of the
same; _fig._ 542. is a longitudinal section of the machine; and _fig._
543. is a transverse section; the similar letters indicating the same
parts in all the figures.

[Illustration: 541 542]

Upon a brick or other suitable base, a furnace or fire-place _a_, is
made, having a descending flue _b_, for the purpose of carrying away the
smoke. A pan or shallow vessel _c c_, formed of lead, is placed over the
furnace; which vessel is intended to contain a sour liquor, as a
solution of vitriolic acid and water. On the edge of this pan is erected
a wooden casing _d d d_, which encloses three sides, leaving the fourth
open for the purpose of obtaining access to the working apparatus
within. A series of what may be termed lantern rollers, _e e e_, is
mounted on axles turning in the side casings; and another series of
similar lantern rollers, _f f f_, is in like manner mounted above. These
lantern rollers are made to revolve by means of bevel pinions, fixed on
the ends of their axles, which are turned by similar bevel wheels on the
lateral shafts _g_ and _h_, driven by a winch _i_, and geer, as shown in
_figs._ 540. and 541.

Having prepared the bodies of the hats, and laid upon their surfaces the
usual coatings of beaver, or other fur, when so prepared they are to be
placed between hair cloths, and these hair cloths folded within a
canvass or other suitable wrapper. Three or more hats being thus
enclosed in each wrapper, the packages are severally put into bags or
pockets in an endless band of sackcloth, or other suitable material;
which endless band is extended over the lantern rollers in the machine.

In the first instance, for the purpose of merely attaching the furs to
the felts (which is called slicking, when performed by hand), Mr. Carey
prefers to pass the endless band _k k k_, with the covered hat bodies,
over the upper series _f f f_, of the lantern rollers, in order to avoid
the inconvenience of disturbing the fur, which might occur from
subjecting them to immersion in the solution contained in the pan,
before the fur had become attached to the bodies.

After this operation of slicking has been effected, he distends the
endless band _k k k_, over the lower series of lantern rollers _e e e_,
and round a carrier roller _l_, as shown in _fig._ 542.; and having
withdrawn the hat bodies for the purpose of examining them, and changing
their folds, he packs them again in a similar way in flannel, or other
suitable cloths, and introduces them into the pockets or bags of the
endless bands, as before.

On putting the machinery in rotatory motion in the way described, the
hats will be carried along through the apparatus, and subjected to the
scalding solution in the pan, as also to the pressure, and to a tortuous
action between the ribs of the lantern rollers, as they revolve, which
will cause the ends of the fur to work into the felted bodies of the
hats, and by that means permanently to attach the nap to the body; an
operation which when performed by hand, is called rolling off.

The improved stiffening for hat bodies proposed by Mr. Blades, under his
patent of January, 1828, consists in making his solution of shellac in
an alkaline lye, instead of spirits of wine, or pyroxylic spirit,
vulgarly called naphtha.

He prepares his water-proof stiffening by mixing 18 pounds of shellac
with 1-1/2 pounds of salt of tartar (carbonate of potash), and 5-1/2
gallons of water. These materials are to be put into a kettle, and made
to boil gradually until the lac is dissolved; when the liquor will
become as clear as water, without any scum upon the top, and if left to
cool, will have a thin crust upon its surface of a whitish cast, mixed
with the light impurities of the gum. When this skin is taken off, the
hat body is to be dipped into the mixture in a cold state, so as to
absorb as much as possible of it; or it may be applied with a brush or
sponge. The hat body being thus stiffened, may stand till it become dry,
or nearly so; and after it has been brushed, it must be immersed in very
dilute sulphuric or acetic acid, in order to neutralize the potash, and
cause the shellac to set. If the hats are not to be napped immediately,
they may be thrown into a cistern of pure water, and taken out as
wanted.

Should the hat bodies have been worked at first with sulphuric acid (as
usual), they must be soaked in hot water to extract the acid, and dried
before the stiffening is applied; care being taken that no water falls
upon the stiffened body, before it has been immersed in the acid.

This ingenious chemical process has not been, to the best of my
knowledge, introduced into the hat manufacture. A varnish made by
dissolving shellac, mastic, sandarach, and other resins in alcohol, or
the naphtha of wood vinegar, is generally employed as the stiffening and
water-proof ingredient of hat bodies. A solution of caoutchouc is often
applied to whalebone and horse-hair hat bodies.

The following recipe has been prescribed as a good composition for
stiffening hats: four parts of shellac, one part of mastic, one half of
a part of turpentine, dissolved in five parts of alcohol, by agitation
and subsequent repose, without the aid of heat. This stiffening varnish
should be applied quickly to the body or foundation with a soft oblong
brush, in a dry and rather warm workshop; the hat being previously
fitted with its inside turned outwards upon a block. The body must be
immediately afterwards taken off, to prevent adhesion.

_Hat-Dyeing._--The ordinary bath for dyeing hats, employed by the London
manufacturers, consists for 12 dozen, of--

  144     pounds of logwood;
   12     pounds of green sulphate of iron, or copperas;
    7-1/2 pounds of verdigris.

The copper is usually made of a semi-cylindrical shape, and should be
surrounded with an iron jacket or case, into which steam may be
admitted, so as to raise the temperature of the interior bath to 190°
F., but no higher, otherwise the heat is apt to affect the stiffening
varnish, called the gum, with which the body of the hat has been imbued.
The logwood having been introduced and digested for some time, the
copperas and verdigris are added in successive quantities, and in the
above proportions, along with every successive two or three dozens of
hats, suspended upon the dipping machine. Each set of hats, after being
exposed to the bath with occasional airings during 40 minutes, is taken
off the pegs, and laid out upon the ground to be more completely
blackened by the peroxidizement of the iron with the atmospheric oxygen.
In 3 or 4 hours the dyeing is completed. When fully dyed, the hats are
well washed in running water.

Mr. Buffum states that there are four principal objects accomplished by
his patent invention for dyeing hats.

1. in the operation;

2. the production of a better colour;

3. the prevention of any of the damages to which hats are liable in the
dyeing;

4. the accomplishment of the dyeing process in a much shorter time than
by the usual methods, and consequently lessening the injurious effects
of the dye-bath upon the texture of the hat.

[Illustration: 544]

_Fig._ 544. shows one method of constructing the apparatus. _a a_ is a
semi-cylindrical shaped copper vessel, with flat ends, in which the
dyeing process is carried on. _b b b_ is a wheel with several circular
rims mounted upon arms, which revolve upon an axle _c_. In the face of
these rims a number of pegs or blocks are set at nearly equal distances
apart, upon each of which pegs or blocks it is intended to place a hat,
and as the wheel revolves, to pass it into and out of the dyeing liquor
in the vat or copper. This wheel may be kept revolving with a very slow
motion, either by geer connecting its axle, _c_, with any moving power,
or it may be turned round by hand, at intervals of ten minutes; whereby
the hats hung upon the pegs, will be alternately immersed for the space
of ten minutes in the dyeing liquor, and then for the same space exposed
to the atmospheric air. In this way, the process of dyeing, it is
supposed, may be greatly facilitated, and improved, as the occasional
transition from the dye vat into the air, and from the air again into
the bath, will enable the oxygen of the atmosphere to strike the dye
more perfectly and expeditiously into the materials of which the hat is
composed, than by a continued immersion in the bath for a much longer
time.

[Illustration: 545]

A variation in the mode of performing this process is suggested, and the
apparatus _fig._ 545. is proposed to be employed, _a a_ is a square vat
or vessel containing the dyeing liquor; _b b_ is a frame or rack having
a number of pegs placed in it for hanging the hats upon, which are about
to be dyed, in a manner similar to the wheel above described. This frame
or rack is suspended by cords from a crane, and may in that way be
lowered down with the hats into the vat, or drawn up and exposed in the
air; changes which may be made every 10 or 20 minutes.

I have seen apparatus of this kind doing good work in the hat-dyeing
manufactories of London, that being a department of the business with
which the Union has not thought it worth their while to interfere.

[Illustration: 546]

Mr. William Hodge’s patent improvements in hat dyeing, partly founded
upon an invention of Mr. Bowler, consist, first in causing every
alternate frame to which the suspenders or blocks are to be attached, to
slide in and out of grooves, for the purpose of more easily removing the
said suspenders when required. _Fig._ 546. represents the improved
dyeing frame, consisting of two circular rims, _a a_, which are
connected together at top and bottom, by three fixed perpendicular bars
or the frame-work _b b b_. Two other perpendicular frames _c c_, similar
to the former, slide in grooves, _d d d d_, fixed to the upper and lower
rims. These grooves have anti-friction rollers in them, for the purpose
of making the frames _c c_, to slide in and out more freely. The
suspenders or substitutes for blocks, by these means, may be more easily
got at by drawing out the frames _c c_, about half way, when the
suspenders, which are attached to the frames with the hats upon them,
may be easily reached, and either removed or altered in position; and
when it is done on one side, the sliding frame may be brought out on the
other, and the remaining quantity of “suspenders” undergo the same
operation.

The patentee remarks, that it is well known to all hat dyers, that after
the hats have been in the dyeing liquor some time, they ought to be
taken out and exposed to the action of the atmospheric air, when they
are again immersed in the copper, that part of the hat which was
uppermost in the first immersion, being placed downwards in the second.
This is done for the purpose of obtaining an uniform and regular dye.
The patentee’s mode of carrying this operation into effect, is shown in
the figure: _e e_ are pivots for the dyeing-frame to turn upon, which is
supported by the arms _f_, from a crane above. The whole apparatus may
be raised up or lowered into the copper by means of the crane or other
mechanism. When the dyeing-frame is raised out of the copper, the whole
of the suspenders or blocks are reversed, by turning the apparatus over
upon the pivots _e e_, and thus the whole surfaces of the hats are
equally acted upon by the dyeing material.

It should be observed, that when the dyeing-frame is raised up out of
the copper, it should be tilted on one side, so as to make all the
liquor run out of the hats, as also to cause the rims of the hats to
hang down, and not stick to the body of the hat, or leave a bad place or
uneven dye upon it. The second improvement described by the patentee, is
the construction of “suspenders,” to be substituted instead of the
ordinary blocks.

[Illustration: 547 548]

These “suspenders” are composed of thin plates of copper, bent into the
required form, that is, nearly resembling that of a hat block, and made
in such a manner as to be capable of contraction and expansion to suit
different sized hats, and keep them distended, which may be altered by
the workman at pleasure, when it is required to place the hats upon
them, or remove them therefrom. The dyeing-frame at _fig._ 546. is shown
with only two of these “suspenders,” in order to prevent confusion. One
of these suspenders is represented detached at _fig._ 547., which
exhibits a side view; and _fig._ 548. a front view of the same. It will
be seen by reference to the figure, that the suspenders consist of two
distinct parts, which may be enlarged or collapsed by a variety of
means, and which means may be suggested by any competent mechanic. The
two parts of the suspenders are proposed to be connected together by
arms _g g_, and at the junction of these arms a key is connected for
turning them round when required. It will be seen on reference to the
front view, _fig._ 548., that the “suspenders” or substitutes for
blocks, are open at the top or crown part of the hat; this is for the
purpose of allowing the dyeing liquor to penetrate.

From the mixture of copperas and verdigris employed in the hat-dye, a
vast quantity of an ochreous muddy precipitate results, amounting to no
less than 25 per cent. of the weight of the copperas. This iron mud
forms a deposit upon the hats, which not only corrodes the fine
filaments of the beaver, but causes both them and the felt stuff to turn
speedily of a rusty brown. There is no process in the whole circle of
our manufactures, so barbarous as that of dyeing stuff hats. No ray of
chemical science seems hitherto to have penetrated the dark recesses of
their dye shops. Some hatters have tried to remove this corrosive brown
ochre by a bath of dilute sulphuric acid, and then counteract the evil
effect of the acid upon the black dye by an alkaline bath; but with a
most unhappy effect. Hats so treated are most deceptious and
unprofitable; as they turn of a dirty brown hue, when exposed for a few
weeks to sunshine and air.


HEALDS, is the harness for guiding the warp threads in a loom; that is,
for lifting a certain number of them alternately to open the shed, and
afford passage to the decussating weft threads of the shuttle. See
WEAVING.


HEARTH; (_Foyer_, Fr.; _Heerde_, Germ.) is the flat or hollow space in a
smelting furnace upon which the ore and fluxes are subjected to the
influence of flame. See COPPER, IRON, METALLURGY, &c.


HEAT, is that power or essence called caloric, the discussion of whose
habitudes with the different kinds of matter belongs to the science of
chemistry.


HEAT-REGULATOR. The name given by M. Bonnemain to an ingenious apparatus
for regulating the temperature of his incubating stove rooms. See
INCUBATION, ARTIFICIAL, for the manner of applying the Heat-Regulator.

[Illustration: 549 549*]

The construction of the regulator is founded upon the unequal dilatation
of different metals by the same degree of heat. A rod of iron _x_,
_fig._ 549., is tapped at its lower end into a brass nut _y_, enclosed
in a leaden box or tube, terminated above by a brass collet _z_. This
tube is plunged into the water of the boiler, alongside of the
smoke-pipe. (_Fig._ 549*. is a bird’s-eye view of the dial, &c.) The
expansion of the lead being more than the iron for a like degree of
temperature, and the rod enclosed within the tube being less easily
warmed, whenever the heat rises to the desired pitch, the elongation of
the tube puts the collet _z_ in contact with the heel _a_, of the bent
lever _a_, _b_, _d_; thence the slightest increase of heat lengthens the
tube anew, and the collet lifting the heel of the lever, depresses its
other end _d_ through a much greater space, on account of the relative
lengths of its legs. This movement operates near the axis of a
balance-bar _e_, sinks one end of this, and thereby increases the extent
of the movement which is transmitted directly to the iron skewer _v_.
This pushing down a swing register diminishes or cuts off the access of
air to the fire-place. The combustion is thereby obstructed, and the
temperature falling by degrees, the tube shrinks and disengages the heel
of the lever. The counterpoise _g_, fixed to the balance-beam _e_,
raises the other extremity of this beam, by raising the end _d_ of the
lever as much as is necessary to make the heel bear upon the collet of
the tube. The swing register acted upon by this means, presents a
greater section to the passage of the air; whence the combustion is
increased. To counterbalance the effect of atmospheric changes, the
iron stem which supports the regulator is terminated by a dial disc,
round the shaft of the needle above _h_, _fig._ 549*.; on turning this
needle, the stem below it turns, as well as a screw at its under end,
which raises or lowers the leaden tube. In the first case, the heel
falls, and opens the swing register, whence a higher temperature is
required to shut it, by the expansion of the tube. We may thus obtain a
regularly higher temperature. If, on the contrary, we raise the tube by
turning the needle in the other direction, the register presents a
smaller opening, and shuts at a lower temperature; in this case, we
obtain a regularly lower temperature. It is therefore easy, says M.
Bonnemain, to determine _à priori_ the degree of temperature to be given
to the water circulating in the stove pipes. In order to facilitate the
regulation of the apparatus, he graduated the disc dial, and inscribed
upon its top and bottom, the words, Strong and Weak heat. See
THERMOSTAT, for another HEAT-REGULATOR.


HEAVY SPAR, _sulphate of Baryta, or Cawk_; (_Spath pesant_, Fr.;
_Schwerspath_, Germ.) is an abundant mineral, which accompanies veins of
lead, silver, mercury, &c. but is often found, also, in large masses.
Its colour is usually white, or flesh-coloured. It occurs in many
crystalline forms, of which the cleavage is a right rhomboidal prism. It
is met with also of a fibrous, radiated, and granular structure. Its
spec. grav. varies from 4·1 to 4·6. It has a strong lustre, between the
fatty and the vitreous. It melts at 35° Wedgew. into a white opaque
enamel. Its constituents are 65·63 baryta, and 34·37 sulphuric acid. It
is decomposed by calcination in contact with charcoal at a white heat,
into sulphuret of baryta; from which all the baryta salts may be readily
formed. Its chief employment in commerce is for adulterating white lead;
a purpose which it readily serves on account of its density. Its
presence here is easily detected by dilute nitric acid, which dissolves
the carbonate of lead, and leaves the heavy spar. It is also a useful
ingredient in some kinds of pottery, and glass.


HECKLE; (_Seran_, Fr.; _Hechel_, Germ.) is an implement for dissevering
the filaments of flax, and laying them in parallel stricks or tresses.
See FLAX.


HELIOTROPE; is a variety of jasper, mixed with chlorite, green earth,
and diallage; occasionally marked with blood-red points; whence its
vulgar name of _bloodstone_.


HEMATINE; is the name given by its discoverer Chevreul to a crystalline
substance, of a pale pink colour, and brilliant lustre when viewed in a
lens, which he extracted from logwood, the _hæmatoxylon Campechianum_ of
botanists. It is, in fact, the characteristic principle of this
dye-wood. To procure hematine, digest during a few hours ground logwood
in water heated to a temperature of about 130° F.; filter the liquor,
evaporate it to dryness by a steam bath, and put the extract in alcohol
of 0·835 for a day. Then filter anew, and after having inspissated the
alcoholic solution by evaporation, pour into it a little water,
evaporate gently again, and then leave it to itself in a cool place. In
this way a considerable quantity of crystals of hematine will be
obtained, which may be readily purified by washing with alcohol and
drying.

When subjected to dry distillation in a retort, hematine affords all the
usual products of vegetable bodies, along with a little ammonia; which
proves the presence of azote. Boiling water dissolves it abundantly, and
assumes an orange-red colour, which passes into yellow by cooling, but
becomes red again with heat. Sulphurous acid destroys the colour of
solution of hematine. Potash and ammonia convert into a dark purple-red
tint, the pale solution of hematine; when these alkalis are added in
large quantity, they make the colour, violet blue, then brown-red, and
lastly brown-yellow. By this time, the hematine has become decomposed,
and cannot be restored to its pristine state by neutralizing the alkalis
with acids.

The waters of baryta, strontia, and lime exercise an analogous power of
decomposition; but they eventually precipitate the changed colouring
matter.

A red solution of hematine subjected to a current of sulphuretted
hydrogen becomes yellow; but it resumes its original hue when the
sulphuretted hydrogen is removed by a little potash.

The protoxide of lead, the protoxide of tin, the hydrate of peroxide of
iron, the hydrate of oxides of copper and nickel, oxide of bismuth,
combine with hematine, and colour it blue with more or less of a violet
cast.

Hematine precipitates glue from its solution in reddish flocks. This
substance has not hitherto been employed in its pure state; but as it
constitutes the active principle of logwood, it enters as an ingredient
into all the colours made with that dye stuff.

These colours are principally violet and black. Chevreul has proposed
hematine as an excellent test of acidity.


HEMATITE; (_Fer Oligiste_, Fr.; _Rotheisenstein_, Germ.) is a native
reddish-brown peroxide of iron, consisting of oxygen 30·66; iron 60·34.
It is the kidney ore of Cumberland, which is smelted at Ulverstone with
charcoal, into excellent steel iron.


HEMP; (_Chanvre_, Fr.; _Hanf_, Germ.) is the fibrous rind of the bark of
the _cannabis sativa_, which is spun into strands or yarn for making
ropes, sail-cloth, &c. It is prepared for spinning in the same way as
flax, which see. _Hemp-seed_ contains an oil which is employed for
making soft soap, for painting, and for burning in lamps. See OILS.

Importation of undressed hemp for home consumption; and amount of duty,
in

          1837.        1838.   |   1837.      1838.
  Cwts. 596,994·3  |  667,017  | _£_2487  | _£_2780


HEPAR; which signifies liver in Latin, was a name given by the older
chemists to some of those compounds of sulphur with the metals which had
a liver-brown colour. Thus the sulphuret of potassium was called liver
of sulphur.


HEPATIC AIR; sulphuretted hydrogen gas.


HERMETICAL SEAL, is an expression derived from Hermes, the fabulous
parent of Egyptian chemistry, to designate the perfect stoppage of a
hollow vessel, by the cementing or melting of the lips of its orifice;
as in the case of a glass thermometer, or matrass.


HIDE; (_Peau_, Fr.; _Haut_, Germ.) the strong skin of an ox, horse, or
other large animal. See LEATHER.

Importation of untanned hides for home consumption; and amount of duty,
in

   1837.       1838.   |    1837.       1838.
  332,877  |  301,890  | _£_46,190  | _£_36,647


HIRCINE; from _hircus_, a ram; is the name given by Chevreul to a liquid
fatty substance, which is mixed with the oleine of mutton suet, and
gives it its peculiar rank smell. Hircine is much more soluble in
alcohol than oleine. It produces _hircic_ acid by saponification.


HOG’s LARD; see FATS.


HONEY; (_Mel_, Fr.; _Honig_, Germ.) is a sweet viscid liquor, elaborated
by bees from the sweet juices of the nectaries of flowers, and deposited
by them in the waxen cells of their combs. Virgin honey is that which
spontaneously flows with a very gentle heat from the comb, and common
honey is that which is procured by the joint agency of pressure and
heat. The former is whitish or pale yellow, of a granular texture, a
fragrant smell, and a sweet slightly pungent taste; the latter is darker
coloured, thicker, and not so agreeable either in taste or smell. Honey
would seem to be merely collected by the bees, for it consists of merely
the vegetable products; such as the sugars of grape, gum, and manna;
along with mucilage, extractive matter, a little wax, and acid.


HONEY-STONE; (_Mellite_, Fr.; _Honigstein_, Germ.) is a mineral of a
yellowish or reddish colour, and a resinous aspect, crystallizing in
octahedrons with a square base; specific gravity 1·58. It is harder than
gypsum, but not so hard as calc-spar; it is deeply scratched by a steel
point; very brittle; affords water by calcination; blackens, then burns
at the flame of the blowpipe, and leaves a white residuum which becomes
blue, when it is calcined after having been moistened with a drop of
nitrate of cobalt. It is a mellate of alumina, and consists of:

                  Klaproth.   Wöhler.

  Mellitic acid      46        44·4
  Alumina            16        14·5
  Water              38        41·1
                    ---       -----
                    100       100·0

The honey-stone, like amber, belongs to the geological formation of
lignites. It has been hitherto found clearly in only one locality, at
Artern in Thuringia.


HOP; (_Houblon_, Fr.; _Hopfen_, Germ.) is the name of a well-known plant
of the natural family of Urticeæ, and of the dioecia pentandria of
Linnæus. The female flowers, placed upon different plants from the male,
grow in ovoid cones formed of oval leafy scales, concave, imbricated,
containing each at the base an ovary furnished with two tubular open
styles, and sharp pointed stigmata. The fruit of the hop is a small
rounded seed, slightly compressed, brownish coloured, enveloped in a
scaly calyx, thin but solid, which contains, spread at its base, a
granular yellow substance, appearing to the eye like a fine dust, but in
the microscope seen to be round, yellow, transparent grains; deeper
coloured, the older the fruit. This secretion, which constitutes the
useful portion of the hop, has been examined in succession by Ives,
Planche, Payen, and Chevallier. I have given a pretty full account of
the results of their researches in treating of the hop, under the
article BEER.


HORDEINE, is the name given by Proust to the peculiar starchy matter of
barley. It seems to be a mixture of the starch, lignine, and husks,
which constitutes barley meal. See BEER.


HORN; (Eng. and Germ.; _Corne_, Fr.) particularly of oxen, cows, goats,
and sheep, is a substance soft, tough semi-transparent, and susceptible
of being cut and pressed into a variety of forms; it is this property
that distinguishes it from bone. Turtle or tortoise shell seems to be of
a nature similar to horn, but instead of being of a uniform colour, it
is variegated with spots.

These valuable properties render horn susceptible of being employed in a
variety of works fit for the turner, snuff-box, and comb maker. The
means of softening the horn need not be described, as it is well known
to be by heat; but those of cutting, polishing, and soldering it, so as
to make plates of large dimensions, suitable to form a variety of
articles, may be detailed. The kind of horn to be preferred is that of
goats and sheep, from its being whiter and more transparent than the
horn of any other animals. When horn is wanted in sheets or plates, it
must be steeped in water, in order to separate the pith from the kernel,
for about fifteen days in summer, and a month in winter; and after it is
soaked, it must be taken out by one end, well shaken and rubbed in order
to get off the pith; after which it must be put for half an hour into
boiling water, then taken out, and the surface sawed even lengthways; it
must again be put into the boiling water to soften it, so as to render
it capable of separating; then, with the help of a small iron chisel, it
can be divided into sheets or leaves. The thick pieces will form three
leaves, those which are thin will form only two, whilst young horn,
which is only one quarter of an inch thick, will form only one. These
plates or leaves must again be put into boiling water, and when they are
sufficiently soft, they must be scraped with a sharp cutting instrument,
to render those parts that are thick even and uniform; they must be put
once more into the boiling water, and finally carried to the press.

At the bottom of the press employed, there must be a strong block, in
which is formed a cavity, of nine inches square, and of a proportionate
depth; the sheets of horn are to be laid within this cavity, in the
following manner: at the bottom, first a sheet of hot iron, upon this a
sheet of horn, next again a sheet of hot iron, and so on, taking care to
place at the top a plate of iron even with the last. The press must then
be screwed down tight.

There is a more expeditious process, at least in part, for reducing the
horn into sheets, when it is wanted very even. After having sawed it
with a very fine and sharp saw, the pieces must be put into a copper
made on purpose, and there boiled, until sufficiently soft, so as to be
able to be split with pincers; the sheets of horn must then be put in
the press, where they are to be placed in a strong vice, the chaps of
which are of iron and larger than the sheets of horn, and the vice must
be screwed as quick and tight as possible; let them cool in the press or
vice, or it is as well to plunge the whole into cold water. The last
mode is preferable, because the horn does not shrink in cooling. Now
draw out the leaves of horn, and introduce other horn to undergo the
same process. The horn so enlarged in pressing, is to be submitted to
the action of the saw, which ought to be set in an iron frame, if the
horn is wanted to be cut with advantage, in sheets of any desired
thickness, which cannot be done without adopting this mode. The thin
sheets thus produced must be kept constantly very warm between plates of
hot iron to preserve their softness; every leaf being loaded with a
weight heavy enough to prevent its warping. To join the edges of these
pieces of horn together, it is necessary to provide strong iron moulds
suited to the shape of the article wanted, and to place the pieces in
contact with copper-plates or with polished metal surfaces against them;
when this is done, the whole is to be put into a vice and screwed up
tight, then plunged into boiling water, and after some time it is to be
removed from thence and immersed in cold water. The edges of the horn
will be thus made to cement together and become perfectly united.

To complete the polish of the horn, the surface must be rubbed with the
subnitrate of bismuth by the palm of the hand. The process is short, and
has this advantage, that it makes the horn dry promptly.

When it is wished to spot the horn in imitation of tortoise-shell,
metallic solutions must be employed as follows:--To spot it red, a
solution of gold in aqua regia must be employed; to spot it black, a
solution of silver in nitric acid must be used; and for brown, a hot
solution of mercury in nitric acid. The right side of the horn must be
impregnated with these solutions, and they will assume the colours
intended. The brown spots can be produced on the horn by means of a
paste made of red lead, with a solution of potash, which must be put in
patches on the horn, and subjected some time to the action of heat. The
deepness of the brown shades depends upon the quantity of potash used in
the paste, and the length of time the mixture lies on the horn. A
decoction of Brazil wood, or a solution of indigo, in sulphuric acid, or
a decoction of saffron, and Berbary wood may also be used. After having
employed these materials, the horn may be left for half a day in a
strong solution of vinegar and alum.

In France, Holland, and Austria, the comb-makers and horn-turners use
the clippings of horn, which are of a whitish yellow, and tortoise-shell
skins, out of which they make snuff-boxes, powder-horns, and many
curious and handsome things. They first soften the horn and shell in
boiling water, so as to be able to submit them to the press in iron
moulds, and by means of heat form them into one mass. The degree of heat
necessary to join the horn clippings must be stronger than that for
shell skins, and it can only be found out by experience. The heat must
not however be too great, for fear of scorching the horn or shell.
Considerable care is required in these operations, not to touch the horn
with the fingers, nor with any greasy body, because the grease will
prevent the perfect joining. Wooden instruments should be used to move
them, while they are at the fire, and for carrying them to the moulds.

In making a ring of horn for bell-pulls, &c., the required piece is to
be first cut out in the flat of its proper dimensions, and nearly in the
shape of a horse-shoe; it is then pressed in a pair of dies to give its
surface the desired pattern; but previous to the pressure, both the
piece of horn and the dies are to be heated; the piece of horn is to be
introduced between the dies, squeezed in a vice, and when cold, the
impression or pattern will be fixed upon the horn. One particular
condition, however, is to be observed in the construction of the dies,
for forming a ring. They are to be so made, that the open ends of the
horse-shoe piece of horn, after being pressed, shall have at one end a
nib, and at the other a recess of a dovetailed form, corresponding to
each other; and the second operation in forming this ring of horn is to
heat it, and place it in another pair of dies, which shall bring its
open ends together, and cause the dovetailed joints to be locked fast
into each other, which completes the ring, and leaves no appearance of
the junction.

In forming the handles of table knives and forks, or other things which
require to be made of two pieces, each of the two pieces or sides of the
handle is formed in a separate pair of dies; the one piece is made with
a counter-sunk groove along each side, and the other piece with
corresponding leaves or projecting edges. When these two pieces are
formed, by first being cut out of the flat horn, then pressed in the
dies in a heated state, for the purpose of giving the pattern, the two
pieces are again heated and put together, the leaves or edges of the one
piece dropping into the counter-sunk grooves of the other piece, and
being introduced between another pair of heated dies, the joints are
pressed together and the two pieces formed into one handle.

In making the knobs for drawers which have metal stems or pins to fasten
them into the furniture, the face of the knob is to be first made in a
die, as above described, and then the back part of the knob with a hole
in it; a metal disc of plate-iron is next provided, in which the metal
stem or screw pin is fixed, and the stem being passed through the
aperture in the back piece, and the two, that is, the back and front
pieces of horn put together, they are then heated and pressed in dies as
above described; the edge of the back piece falling into the
counter-sunk groove of the front piece, while by the heat they are
perfectly cemented together.


HORNSILVER; (_Argent Corné_, or _Kerargyre_, Fr; _Hornsilber_, Germ.) is
a white or brownish mineral, sectile like wax or horn; and crystallizing
in the cubic system. Its specific gravity varies from 4·75 to 5·55.
Insoluble in water; not volatile; fusible at the blowpipe, but difficult
of reduction by it. It deposits metallic silver when rubbed with water
upon a piece of clean copper or iron. It consists of 24·67 chlorine, and
75·32 silver.

Hornsilver is rare in the European mines, but it occurs in great
quantity in the districts of Zacatecas, Fresnillo, and Catarce, in
Mexico; and in Huantajaya, Yauricocha, &c., in Peru; where it is
abundantly mixed with the ores of hydrate of iron, called Pacos and
Colorados, interspersed with veins of metallic silver, which form
considerable deposits in the _penæan_ limestones. There it is profitably
mined as an ore of silver.


HORNSTONE; is a variety of rhomboidal quartz. Being both hard and tough,
it is well adapted to form the stones of pottery mills for grinding
flints; it is called chert in Derbyshire, where it abounds.

_Hornstone_ occurs under three modifications; splintery hornstone,
conchoidal hornstone, and woodstone. The colours of the first two are
gray, white, and red; they are all massive; dull, or of a glimmering
lustre. Translucent only on the thin edges. Difficult to break.
Hornstone is less brittle than flint; and by its infusibility before the
blowpipe it may be distinguished from petrosilex, which it resembles in
external appearance. The geological locality of hornstone is remarkable;
for it occurs in both ancient and recent formations. It is found
frequently in the veins that traverse primitive crystalline rocks,
filling up the interstices, and enveloping their metallic ores. In the
lead mine of Huelgoët in Brittany it is whitish; but its prevailing
colour is gray. It occurs likewise in the middle beds of the coarse
limestone (_calcaire grossier_) in the Paris basin, which is a
comparatively modern formation, as well as in the sand beds of the upper
parts of this district, near Saint Cloud, Neuilly, &c. The hornstone
which occurs in secondary limestone is called _chert_ by the English
miners. It is valuable for forming the grinding blocks of flint mills in
the pottery manufacture.


HORSE POWER, in steam engines, is estimated by Mr. Watt at 32,000 pounds
avoirdupois lifted one foot high per minute, for one horse. M.
D’Aubuisson, from an examination of the work done by horses in the
whims, or gigs (_machines à molettes_) for raising ore from the mines at
Freyberg, the horses being of average size and strength, has concluded
that the useful effect of a horse yoked during eight hours, by two
relays of four hours each, in a manege or mill course, may be estimated
at 40 kilogrammes raised 1 mètre per second; which is nearly 16,440
pounds raised one foot per minute; being very nearly one half of Mr.
Watt’s liberal estimate for the work of his steam engines.


HOSIERY; (_Bonnèterie_, Fr.; _Strumpfweberei_, Germ.) The _stocking
frame_, which is the great implement of this business, though it appears
at first sight to be a complicated machine, consists merely of a
repetition of parts easily understood, with a moderate degree of
attention, provided an accurate conception is first formed of the nature
of the hosiery fabric. This texture is totally different from the
rectangular decussation which constitutes cloth, as the slightest
inspection of a stocking will show; for this, instead of having two
distinct systems of thread, like the warp and the weft, which are woven
together, by crossing each other at right angles, the whole piece is
composed of a single thread united or looped together in a peculiar
manner, which is called stocking-stitch, and sometimes chain-work.

[Illustration: 550 551]

This is best explained by the view in _fig._ 550. A single thread is
formed into a number of loops or waves, by arranging it over a number of
parallel needles, as shewn at R: these are retained or kept in the form
of loops or waves, by being drawn or looped through similar loops or
waves formed by the thread of the preceding course of the work, S. The
fabric thus formed by the union of a number of loops is easily
unravelled, because the stability of the whole piece depends upon the
ultimate fastening of the first end of the thread; and if this is
undone, the loops formed by that end will open, and release the
subsequent loops one at a time, until the whole is unravelled, and drawn
out into the single thread from which it was made. In the same manner,
if a thread in a stocking piece fails, or breaks at any part, or drops a
stitch, as it is called, it immediately produces a hole, and the
extension of the rest can only be prevented by fastening the end. It
should be observed that there are many different fabrics of
stocking-stitch for various kinds of ornamental hosiery, and as each
requires a different kind of frame or machine to produce it, we should
greatly exceed our limits to enter into a detailed description of them
all. That species which we have represented in _fig._ 550. is the common
stocking-stitch used for plain hosiery, and is formed by the machine
called the common stocking-frame, which is the groundwork of all the
others. The operation, as we see, consists in drawing the loop of a
thread successively through a series of other loops, so long as the work
is continued, as is very plainly shown for one stitch in _fig._ 551.

There is a great variety of different frames in use for producing
various ornamental kinds of hosiery. The first, which forms the
foundation of the whole, is that for knitting plain hosiery, or the
common stocking-frame.

[Illustration: 552]

Of this valuable machine, the invention of Mr. Lee of Cambridge, a side
elevation is given in _fig._ 552., with the essential parts. The framing
is supported by four upright posts, generally of oak, ash, or other hard
wood. Two of these posts appear at A A, and the connecting cross rails
are at C C. At B is a small additional piece of framing, which supports
the hosier’s seat. The iron-work of the machine is bolted or screwed to
the upper rails of the frame-work, and consists of two parts. The first
rests upon a sole of polished iron, which appears at D, and to which a
great part of the machinery is attached. The other part, which is
generally called the carriage, runs upon the iron sole at D, and is
supported by four small wheels, or trucks, as they are called by the
workmen. At the upper part of the back standard of iron are joints, one
of which appears at Q; and to these is fitted a frame, one side of which
is seen extending to H. By means of these joints, the end at H may be
depressed by the hosier’s hand, and it returns, when relieved, by the
operation of a strong spring of tempered steel, acting between a cross
bar in the frame, and another below. The action of this spring is very
apparent in _fig._ 553. In the front of the frame, immediately opposite
to where the hosier sits, are placed the needles which form the loops.
These needles, or rather hooks, are more or less numerous, according to
the coarseness or fineness of the stocking; and this, although
unavoidable, proves a very considerable abatement of the value of a
stocking-frame. In almost every other machine (for example those
employed in spinning or weaving), it is easy to adapt any one either to
work coarser or finer work, as it may be wanted. But in the manufacture
of hosiery, a frame once finished, is limited for ever in its operation
to the same quality of work, with this exception, that by changing the
stuff, the work may be made a little more dense or flimsy; but no
alteration in the size or quantity of loops can take place. Hence where
the manufacture is extensively prosecuted, many frames may be thrown
idle by every vicissitude of demand; and where a poor mechanic does
purchase his own frame, he is for ever limited to the same kind of work.
The gauge, as it is called, of a stocking-frame is regulated by the
number of loops contained in three inches of breadth, and varies very
much; the coarsest frames in common use being about what are termed
Fourteens, and the finest employed in great extent about Forties. The
needles are of iron wire, the manufacture of which is very simple; but
long practice in the art is found necessary before a needle-maker
acquires the dexterity which will enable him both to execute his work
well, and in sufficient quantity to render his labour productive.

[Illustration: 553]

The process of making the needles is as follows:--Good sound iron wire,
of a proper fineness, is to be selected; that which is liable to split
or splinter, either in filing, punching, or bending, being totally unfit
for the purpose. The wire is first to be cut into proper lengths,
according to the fineness of the frame for which the needles are
designed, coarse needles being considerably longer than fine ones. When
a sufficient number (generally some thousands) have been cut, the wire
must be softened as much as possible. This is done by laying them in
rows in a flat iron box, about an inch deep, with a close cover; the box
being filled with charcoal between the strata of wires. This box, being
placed upon a moderate fire, is gradually heated until both the wires
and charcoal have received a moderate red heat, because, were the heat
increased to what smiths term the white heat, the wire would be rendered
totally unfit for the subsequent processes which it has to undergo, both
in finishing and working. When the box has been sufficiently heated, it
may be taken from the fire, and placed among hot ashes, until both ashes
and box have gradually cooled; for the slower the wires cool, the softer
and easier wrought they will be. When perfectly cool, the next process
is to punch a longitudinal groove in the stem of every needle, which
receives the point or barb, when depressed. This is done by means of a
small engine worked by the power of a screw and lever. The construction
of these engines is various; but a profile elevation of one of the most
simple and commonly used will be found in _fig._ 553. It consists of two
very strong pieces of malleable iron, represented at A and C, and these
two pieces are connected by a strong well-fitted joint at B. The lower
piece, or sole of the engine at C, is screwed down by bolts to a strong
board or table, and the upper piece A will then rise or sink at
pleasure, upon the joint B. In order that A may be very steady in rising
and sinking, which is indispensable to its correct operation, a strong
bridle of iron, which is shewn in section E, is added to confine it, and
direct its motion. In the upper part of this bridle is a female screw,
through which the forcing screw passes, which is turned by the handle or
lever D. To the sole of the engine C is fixed a bolster of tempered
steel, with a small groove to receive the wire, which is to be punched;
and in the upper or moving part A, is a sharp chisel, which descends
exactly into the groove, when A is depressed by the screw. These are
represented at F, and above H. At G is a strong spring, which forces up
the chisel when the pressure of the screw is removed. The appearance of
the groove, when the punching is finished, will be rendered familiar by
inspecting _fig._ 554., p. 651. When the punching is finished, the wires
are to be brought to a fine smooth point by filing and burnishing, the
latter of which should be very completely done, as, besides polishing
the wire, it tends greatly to restore that spring and elasticity which
had been removed by the previous operation of softening. The wire is
next to be bent, in order to form the hook or barb; and this is done
with a small piece of tin plate bent double, which receives the point of
the wire, and by its breadth regulates the length of the barb. The stem
of the needle is now flattened with a small hammer, to prevent it from
turning in the tin socket in which it is afterwards to be cast; and the
point of the barb being a little curved by a pair of small plyers, the
needle is completed.

[Illustration: 554 555]

In order to fit the needles for the frame, they are now cast into the
tin sockets, or leads as they are called by the workmen; and this is
done by placing the needles in an iron mould, which opens and shuts by
means of a joint, and pouring in the tin while in a state of fusion. In
common operations, two needles are cast into the same socket. The form
of the needle, when complete and fitted to its place in the frame, will
be seen in _fig._ 555., which is a profile section of the needle-bar
exhibiting one needle. In this figure a section of the presser is
represented at F; the needle appears at G, and the socket or level at K.
At H, is a section of the needle-bar, on the fore part of which is a
small plate of iron called a verge, to regulate the position of the
needles. When placed upon the bar resting against the verge, another
plate of iron, generally lined with soft leather, is screwed down upon
the sockets or leads, in order to keep them all fast. This plate and the
screw appear at I. When the presser at F, is forced down upon the barb,
this sinks into the groove of the stem, and the needle is shut; when the
presser rises, the barb opens again by its own elasticity.

[Illustration: 556 557]

The needles or hooks being all properly fitted, the next part of the
stocking-frame to which attention ought to be paid, is the machinery for
forming the loops; and this consists of two parts. The first of these,
which sinks between every second or alternate needle, is represented at
O, _fig._ 552., and is one of the most important parts of the whole
machine. It consists of two moving parts; the first being a succession
of horizontal levers moving upon a common centre, and called jacks, a
term applied to vibrating levers in various kinds of machinery as well
as the stocking-frame. One only of these jacks can be represented in the
profile _fig._ 552.; but the whole are distinctly shown in a horizontal
position in _fig._ 556.; and a profile upon a very enlarged scale is
given in _fig._ 557. The jack shewn in _fig._ 552., extends
horizontally from O to I, and the centre of motion is at R. On the
front, or right hand part of the jack at O, is a joint suspending a very
thin plate of polished iron, which is termed a sinker. One of these
jacks and sinkers is allotted for every second or alternate needle. The
form of the sinker will appear at S, _fig._ 557.; and in order that all
may be exactly uniform in shape, they are cut out and finished between
two stout pieces of iron, which serve as moulds or gauges to direct the
frame-smith. The other end of the jack at I, is tapered to a point; and
when the jacks are in their horizontal position, they are secured by
small iron springs, one of which is represented at I, _fig._ 552., each
spring having a small obtuse angled notch to receive the point of the
jack, against which it presses by its own elasticity. In _fig._ 557. the
centre is at R; the pointed tail is omitted for want of room, the joint
is at O, and the throat of the sinker, which forms the loop, is at S.
The standards at R, upon which the jack moves, are called combs, and
consist of pieces of flat smooth brass, parallel to, and equidistant
from each other. The cross-bar R, which contains the whole, is of iron,
with a perpendicular edge or rim on each side, leaving a vacancy between
them, or a space to receive the bottom part or tails of the combs. The
combs are then placed in the bar, with a flat piece of brass called a
countercomb, between each, to ascertain and preserve their distances
from each other. These countercombs are exactly of the same shape as the
combs, but have no tails. When both combs and countercombs are placed in
the bar, it is luted with clay so as to form a mould, into which is
poured a sufficient quantity of melted tin. When the tin has had time to
cool, the countercombs having no tails are easily taken out, and the
combs remain well fastened and secured by the tin, which has been fused
entirely round them. Thus they form a succession of standards for the
jacks; and a hole being drilled through each jack and each comb, one
polished wire put through, serves as a common centre for the whole.

[Illustration: 558]

The jack sinkers being only used for every alternate or second needle,
in order to complete this part of the apparatus, a second set of sinkers
is employed. These are, in form and shape, every way the same as the
jack sinkers, but they are jointed at the top into pieces of tin, all of
which are screwed to the sinker bar H, _fig._ 552.; and thus a sinker of
each kind descends between the needles alternately. By these sinkers the
loops are formed upon all the needles, and the reason of two sets
different in operation being employed, will be assigned in describing
the mode of working the frame. The presser of the operation, of which
something has already been said, appears at F; and of the two arms which
support and give motion to it, one appears very plainly at E, its centre
of motion being at C. The circular bend given to these arms, besides
having an ornamental effect, is very useful, in order to prevent any
part from interfering with the other parts which are behind, by
elevating them entirely above them. The extremity of these arms at the
termination of the bends behind, are connected by a cross bar, which has
also a circular bend in the middle, projecting downwards, for a reason
similar to that already assigned. This bend is concealed in _fig._ 552.,
but visible in the front elevation, _fig._ 558. From the middle of the
bend, the presser is connected with the middle treadle by a depending
wire appearing at M, _fig._ 552., and thus, by the pressure of that
treadle, the presser is forced down to close the barbs of the needle.
The re-ascent of the presser is sometimes effected by means of a
counterpoising weight passing over a pulley behind; and sometimes by the
reaction of a wooden spring, formed of a strong hoop like that
represented at K. The latter of these is preferred, especially by the
Nottingham hosiers, because, as they assert, it makes the presser spring
up with greater rapidity, and consequently saves time in working. How
far this may be practically the case, it would be superfluous here to
investigate; but it is obvious that the wooden spring, if very stiff,
must add much to the hosier’s exertion of his foot, already exercised
against the united spring of all his barbs; and this inconvenience is
much complained of by those who have been accustomed to work with the
counterpoise.

[Illustration: 559 560 561]

At L are two pulleys or wheels, of different diameters, moving upon a
common centre, by which the jack sinkers are relieved from the back
springs, and thrown downwards to form the loops upon the needles. About
the larger wheel is a band of whipcord, passing twice round, the
extremities of which are attached to what is called the slur, which
disengages the jacks from the back springs. The smaller pulley, by
another band, communicates with the right and left treadle; so that
these treadles, when pressed alternately, turn the pulleys about in an
inverted order. The directions of these bands also appear more plainly
in the front elevation, _fig._ 558. The construction of the slur, and
its effect upon the jacks, will also be rendered apparent by _fig._ 559.
In this figure, eight jacks are represented in section, the tail part of
three of which, 1, 2, 3, are thrown up by the slur in its progress from
left to right; the fourth is in the act of rising, and the remaining
four, 5, 6, 7, and 8, are still unacted upon, the slur not yet having
reached them. As the slur acts in the direction of the dotted line X, X,
_fig._ 556., behind the centres of the jacks, it is hardly necessary to
remark, that this forcing up of the tails must of course depress the
joints by which the sinkers in front are suspended. The jack sinkers
falling successively from the loops on every alternate needle, in the
way represented at _fig._ 560., where both kinds of sinkers appear in
section, the light part expressing what is above the point at which the
throat of the sinker operates upon the thread, and the dark part what is
below. The second set, or, as they are called, the lead sinkers, from
the manner of jointing them, and suspending them from the bar above,
appear still elevated; the position of the bar being represented by the
line A, B. But when these are pulled down to the level of the former by
the operator’s hands, the whole looping will be completed, and the
thread C, D, which is still slack, will be brought to its full and
proper degree of tension, which is regulated by stop screws, so as to be
tempered or altered at pleasure. The sinking of this second set of
sinkers, may be easily explained by _fig._ 561. The direction of the
sinkers is expressed by the line E; the bar from which they are
suspended will be at A; the top frame is in the direction from A to B;
the back standards at D, and the joint at B, is the centre of motion. If
E is pulled perpendicularly downwards, the spring C, will be contracted,
and its upper extreme point G, will be brought nearer to its lower
extreme point F, which is fixed. Again, when the force which has
depressed E is removed, the spring C will revert to its former state,
and the sinkers will rise. The raising of the jack sinkers and jacks
takes place at the same time, by the hosier raising his hands; and for
the cause of this we must revert to _fig._ 556. The lead sinkers in
rising, lay hold of notches, which raise the extreme parts of the set of
jacks Z, Z, which are called half-jacks. Between the extremities of
these at Z, Z, is a cross bar, which, in descending, presses all the
intermediate jacks behind the common centre, and restores them to their
original posture, where they are secured by the back springs, until they
are again relieved by the operation of the slur recrossing at the next
course.

_Working of the frame._--In order to work a frame, the whole apparatus
being previously put into complete order, the hosier places himself on
the seat B in front, and provides himself with a bobbin of yarn or
stuff. This bobbin he places loosely on a vertical pin of wire, driven
into one side of the frame contiguous to the needles, so that it may
turn freely as the stuff is unwound from it. Taking the thread in his
hand, he draws it loosely along the needles, behind the barbs, and under
the throats of the sinkers. He then presses down one of the treadles to
pass the slur along, and unlock the jacks from the back springs, that
they may fall in succession. When this is done, the number of loops thus
formed is doubled by bringing down the lead sinkers, and the new formed
loops are lodged under the barbs of the needles by bringing forward the
sinkers. The preceding course, and former fabric, being then again
pushed back, the barbs are shut by depressing the middle treadle, and
forcing down the presser upon the needles. The former work is now easily
brought over the shut needles, after which, by raising the hands, both
sets of sinkers are raised; the jacks are locked by the back springs,
and the hosier goes on to another course.

From this it will be apparent, that the remark made in the outset is
well founded, that there are in reality, no complicated or difficult
movements in the stocking-frame. Almost the whole are merely those of
levers moving upon their respective fulcra, excepting that of the
carriage which gives the horizontal motion to the sinkers, and that is
merely an alternate motion on four wheels. Yet the frame is a machine
which requires considerable experience and care, both to work it to
advantage, and also to keep it in good order. This circumstance arises
greatly from the small compass in which a number of moving parts must be
included. Owing to this, the needles, unless cautiously and delicately
handled, are easily bent or injured. The same circumstance applies with
equal or greater force to the sinkers, which must be so very thin as to
be easily injured. But as these must work freely, both in a
perpendicular and horizontal direction between the needles, in a very
confined and limited space, the slightest variation in either, from
being truly and squarely placed, unavoidably injures the others. When a
hosier, either ignorant of the mechanical laws, of their relation to
each other, or too impatient to wait for the assistance of another,
attempts to rectify defects, he in most cases increases them tenfold,
and renders the machine incapable of working at all, until repaired by
some more experienced person. This circumstance has given rise to a set
of men employed in this trade, and distinguished by the name of
upsetters; and these people, beside setting new frames to work, have
frequently more employment in repairing old ones injured by want of care
or skill, than many country apothecaries, who live in unhealthy
parishes, find in tampering with the disorders of mankind.

It seems unnecessary to go further into detail respecting a machine so
well known, and which requires practical attention even more than most
others. It may, therefore, be sufficient to describe shortly some of its
varieties, the most simple and common of which is the rib
stocking-frame.

_Rib stocking-frame._--This frame, which, next to the common frame, is
most extensively in use, is employed for working those striped or ribbed
stockings, which are very common in all the different materials of which
hosiery is formed. In principle it does not differ from the common
frame, and not greatly in construction. The preceding general
description will nearly apply to this machine with equal propriety as to
the former: that part, however, by which the ribs or stripes are formed,
is entirely an addition, and to the application of this additional
machinery it may be proper to pay the chief attention, referring chiefly
to _fig._ 558., which is a front elevation.

[Illustration: 562]

This figure has been already referred to for the illustration of those
parts of the machinery which are common to both, and those parts
therefore require no recapitulation. The principle of weaving ribbed
hosiery possesses considerable affinity to that which subsists in the
weaving of that kind of cloth which is distinguished by the name of
tweeling, for the formation of stripes, with some variation arising
merely from the different nature of the fabric. In cloth weaving, two
different kinds of yarn intersecting each other at right angles, are
employed; in hosiery only one is used. In the tweeling of cloth, striped
as dimity, in the cotton or kerseymere, and in the woollen manufacture,
the stripes are produced by reversing these yarns. In hosiery, where
only one kind of yarn is used, a similar effect is produced by reversing
the loops. To effect this reversing of the loops, a second set of
needles is placed upon a vertical frame, so that the bends of the hooks
may be nearly under those of the common needles. These needles are cast
into tin moulds, pretty similar to the former, but more oblique or
bevelled towards the point, so as to prevent obstructions in working
them. They are also screwed to a bar of iron, generally lighter than the
other, and secured by means of plates: this bar is not fixed, but has a
pivot in each end, by means of which the bar may have a kind of
oscillatory motion on these pivots. Two frames of iron support this bar;
that in which it oscillates being nearly vertical, but inclined a little
towards the other needles. _Fig._ 562., which is a profile elevation,
will serve to illustrate the relative position of each bar to the other.
The lower or horizontal frame, the ends only of which can be seen in
_fig._ 558. under _a a_, appears in profile in _fig._ 562., where it is
distinguished by _d_. The vertical frame at _a_ is attached to this by
two centre screws, which serve as joints for it to move in. On the top
of this frame is the rib-needle bar at _f_, in _figs._ 552. and 562.,
and one needle is represented in _fig._ 562. at _f_. At _g_ is a small
presser, to shut the barbs of the rib-needles, in the same manner as the
large one does those of the frame. At _h_ is one of the frame needles,
to show the relative position of the one set to the other. The whole of
the rib-bar is not fitted with needles like the other; for here needles
are only placed where ribs or stripes are to be formed, the intervals
being filled up with blank leads, that is to say, with sockets of the
same shape as the others, but without needles; being merely designed to
fill the bar and preserve the intervals. Two small handles depend from
the needle bar, by which the oscillatory motion upon the upper centres
is given. The rising and sinking motion is communicated to this machine
by chains which are attached to iron sliders below, and which are
wrought by the hosier’s heel when necessary. The pressure takes place
partly by the action of the small presser, and partly by the motion of
the needles in descending, A small iron slider is placed behind the
rib-needles, which rises as they descend, and serves to free the loops
perfectly from each other.

In the weaving of ribbed hosiery, the plain and rib courses are wrought
alternately. When the plain are finished, the rib-needles are raised
between the others, but no additional stuff is supplied. The rib-needles
intersecting the plain ones, merely lay hold of the last thread, and, by
again bringing it through that which was on the rib-needle before, give
it an additional looping, which reverses the line of chaining, and
raises the rib above the plain intervals, which have only received a
single knitting.

[Illustration: 563]


HOT-FLUE, is the name given in England to an apartment heated by stoves
or steam pipes, in which padded and printed calicoes are dried hard.
_Fig._ 563. represents the simplest form of such a flue, heated by the
vertical round iron stove C, from whose top a wide square pipe proceeds
upwards in a slightly inclined direction, which receives the current of
air heated by the body and capital of the stove. In this wide channel
there are pullies, with cords or bands which, suspend by hooks, and
conduct the web of calico, from the entrance at B, where the operative
sits, to near the point A, and back again. This circuit may be repeated
once or oftener till the goods are perfectly dried. At D the driving
pulley connected with the main shaft is shown. Near the feet of the
operative is the _candroy_ or reel upon which the moist goods are rolled
in an endless web; so that their circulation in the hot-air channel can
be continued without interruption, as long as may be necessary.

[Illustration: 564]

_Fig._ 564. is a cross section of the apparatus of the regular hot-flue,
as it is mounted in the most scientific calico works of England, those
of James Thomson, Esq., of Primrose, near Clitheroe, Lancashire. _a a a
a_, is an arched apartment, nearly 30 yards long, by 13 feet high, and
10 feet wide. Through about one half of this gallery there is a
horizontal floor supported on arches, above which is the driest space,
through which the goods are finally passed before they escape from the
hot-flue, after they have been previously exposed to the hot but
somewhat moist air of the lower compartment. A large square flue covered
with cast-iron plates runs along the whole bottom of the gallery. It is
divided into two long parallel vaults, whose sections are seen at _u_,
_u_, _fig._ 564., covered with the cast-iron plates _v v_, grooved at
their ends into one another. The thickness of these plates is increased
progressively as they come nearer to the fireplace or furnace. There are
dampers which regulate the draught, and of course the heat of the stove.
_h h_ are the air-passages or vent-holes, left in the side walls, and
which by means of a long iron rod, mounted with iron plates, may be
opened or closed together to any degree. _k k_ are the cast-iron
supports of the tinned brass rollers which guide the goods along, and
which are fixed to the cross pieces represented by _r r_, _fig._ 564. _l
l_ are iron bars for supporting the ventilators or fans (see the fan
under FOUNDRY). These fans are here enclosed within a wire grating. They
make about 300 turns per minute, and expel the moist air with perfect
effect. _s_ indicates the position of the windows, which extend
throughout the length of the building. _t_ is a gas-light jet, placed at
the side of each window to supply illumination for night work.

The piece is stretched along the whole extent of the gallery, and runs
through it in the course of one minute and a half; being exposed during
its passage to the heat of 212° Fahr.

[Illustration: 565]

In _fig._ 565., A is the iron door of entrance to the hot-flue gallery;
at _b_ is the padding machine, where the goods are imbued with the
general mordant. The speed of this machine may be varied by means of the
two conical drums _c c_, which drive it; since when the band _c c_, is
brought by its forks, and adjusting screws, nearer to the narrow end of
the lower drum, the cylinder upon the same shaft with the latter is
driven quicker; and _vice versa_. Over D D the cords are shown for
drawing the drum mechanism into geer with the main shaft band F, F, E;
or for throwing it out of geer. The pullies F F carry the bands which
transmit the motion to the padding machine. A cylindrical drum exterior
to the hot-flue, covered with flannel, serves to receive the end of the
series of pieces, and to draw them through the apartment. This mode of
drying the padded calicoes requires for each piece of 28 yards, 3
pounds of coals for the furnace when a fan is employed, and 4 pounds
without it.


HYDRATES; are compounds of the oxides, salts, &c. with water in definite
or equivalent proportions. Thus slaked lime consists of one atom of
quick-lime = 28, + one atom of water = 9, of which the sum is 37 on the
hydrogen scale.


HYDRAULIC PRESS. See OIL, PRESS, and STEARINE.


HYDRIODIC ACID; (_Acide Hydriodique_, Fr.; _Hydriodsäure_, Germ.) is an
acid formed by the combination of 99·21 parts of iodine, and 0·79
hydrogen. When pure, it occurs in the gaseous state, but it combines
with water like the hydrochloric or muriatic acid gas into a liquid
acid.


HYDROCHLORIC ACID; the new chemical name of muriatic acid, which see.


HYDROGEN; (Eng. and Fr.; _Wasserstoff_, Germ.) an undecompounded gaseous
body; the lightest of all ponderable matter, whose examination belongs
to chemistry.


HYDROMETER; an instrument for ascertaining the specific gravities of
liquids. Baumé’s hydrometer, which is much used in France, and other
countries of the continent of Europe, when plunged in pure water, at the
temperature of 58° Fahr., marks 0 upon its scale; in a solution
containing 15 per cent. of common salt, (chloride of sodium) and 85 of
water by weight, it marks 15°; so that each degree is meant to indicate
a density corresponding to one per cent. of that salt. See AREOMETER,
for comparative tables of hydrometers.


HYDROSULPHURETS; chemical compounds of bases with sulphuretted hydrogen.


HYMENŒA COURBARIL; a tree growing in South America, from which the resin
_animé_ exudes.


HYOSCIAMUS NIGER. Henbane is a plant used in medicine, from which modern
chemistry has extracted a new crystalline vegetable principle called
_hyosciamine_, which is very poisonous, and when applied in solution to
the eye, determines a remarkable dilatation of the pupil; as
_belladonna_ also does.


HYPOSULPHATES; HYPOSULPHITES; saline compounds of the hyposulphuric or
hyposulphurous acid with bases.


HYPEROXYMURIATES; the old and incorrect name of CHLORATES.




I. & J.


JACK, called also _jack in a box_, and _hand-jack_, is a portable,
mechanical instrument, consisting of a rack and pinion, or a pair of
claws and ratchet bar, moved by a winch handle, for raising heavy
weights a little way off the ground.


JACK and JACK-SINKERS, are parts of a stocking frame; see HOSIERY.


JACK-BACK, is the largest jack of the brewer.


JACQUARD. A peculiar and most ingenious mechanism, invented by M.
Jacquart of Lyons, to be adapted to a silk or muslin loom for
superseding the employment of draw-boys, in weaving figured goods.
Independently of the ordinary play of the warp threads for the formation
of the ground of such a web, all those threads which should rise
simultaneously to produce the figure, have their appropriate healds,
which a child formerly raised by means of cords, that grouped them
together into a system, in the order, and at the time desired by the
weaver. This plan evidently occasioned no little complication in the
machine, when the design was richly figured; but the apparatus of
Jacquart, which subjects this manœuvre to a regular mechanical
operation, and derives its motion from a simple pedal put in action by
the weaver’s feet, was generally adopted soon after its invention in
1800. Every common loom is susceptible of receiving this beautiful
appendage. It costs in France, 200 francs, or 8_l._ sterling; and a
little more in this country.

[Illustration: 566 567 568]

_Fig._ 566. is a front elevation of this mechanism, supposed to be let
down. _Fig._ 567. is a cross section, shown in its highest position.
_Fig._ 568. the same section as the preceding, but seen in its lower
position.

A, is the fixed part of the frame, supposed to form a part of the
ordinary loom; there are two uprights of wood, with two cross-bars
uniting them at their upper ends, and leaving an interval _x y_, between
them, to place and work the movable frame B, vibrating round two fixed
points _a a_, placed laterally opposite each other, in the middle of the
space _x y_, _fig._ 566.

C, is a piece of iron with a peculiar curvature, seen in front, _fig._
566., and in profile, _figs._ 567. and 568. It is fixed on one side upon
the upper cross-bar of the frame B, and on the other, to the
intermediate cross-bar _b_ of the same frame, where it shows an inclined
curvilinear space _c_, terminated below by a semi-circle.

[Illustration: 569 570]

D, is a square wooden axis, movable upon itself round two iron pivots,
fixed into its two ends; which axis occupies the bottom of the movable
frame B. The four faces of this square axis are pierced with three
round, equal, truly-bored holes, arranged in a quincunx. The teeth _a_,
_fig._ 570., are stuck into each face, and correspond to holes _a_,
_fig._ 573., made in the cards which constitute the endless chain for
the healds; so that in the successive application of the cards to each
face of the square axis, the holes pierced in one card may always fall
opposite to those pierced in the other. The right-hand end of the
square axis, of which a section is shown in double size, _fig._ 569.,
carries two square plates of sheet iron _d_, kept parallel to each other
and a little apart, by four spindles _e_, passed opposite to the
corners. This is a kind of lantern, in whose spindles, the hooks of the
levers _f f´_, turning round fixed points _g g´_ beyond the right hand
upright A, catch hold, either above or below at the pleasure of the
weaver, according as he merely pulls or lets go the cord _z_, during the
vibratory movement of the frame B.

E is a piece of wood shaped like a T, the stem of which prolonged
upwards, passes freely through the cross-bar _b_, and through the upper
cross-bar of the frame B, which serve as guides to it. The head of the T
piece being applied successively against the two spindles _e_, placed
above in a horizontal position, first by its weight, and then by the
spiral spring _h_, acting from above downwards, keeps the square axis in
its position, while it permits it to turn upon itself in the two
directions. The name _press_ is given to the assemblage of all the
pieces which compose the movable frame B B.

F is a cross-bar made to move in a vertical direction by means of the
lever G, in the notches or grooves _i_, formed within the fixed uprights
A.

H, is a piece of bent iron, fixed by one of its ends with a nut and
screw, upon the cross-bar F, out of the vertical plane of the piece C.
Its other end carries a friction roller J, which working in the
curvilinear space _c_ of the piece C, forces this, and consequently the
frame B to recede from the perpendicular, or to return to it, according
as the cross-bar F is in the top or bottom of its course, as shown in
_figs._ 567. and 568.

I, cheeks of sheet iron attached on either side to the cross-bar F,
which serve as a safe to a kind of claw K, composed here of eight small
metallic bars, seen in section _fig._ 567. and 568., and on a greater
scale in _fig._ 570.

J, upright skewers of iron wire, whose tops bent down hook-wise,
naturally place themselves over the little bars K. The bottom of these
spindles likewise hooked in the same direction as the upper ones,
embraces small wooden bars _l_, whose office is to keep them in their
respective places, and to prevent them from twirling round, so that the
uppermost hooks may be always directed towards the small metallic bars
upon which they impend. To these hooks from below are attached strings,
which after having crossed a fixed board _m n_, pierced with
corresponding holes for this purpose, proceed next to be attached to the
threads of the loops destined to lift the warp threads. K K, horizontal
spindles or needles, arranged here in eight several rows, so that each
spindle corresponds both horizontally and vertically to each of the
holes pierced in the four faces of the square axis D. There are
therefore as many of these spindles as there are holes in one of the
faces of the square.

[Illustration: 571]

_Fig._ 571. represents one of these horizontal spindles. _n_ is an
eyelet through which the corresponding vertical skewer passes. _o_
another elongated eyelet, through which a small fixed spindle passes to
serve as a guide, but which does not hinder it from moving length-wise,
within the limits of the length of the eyelet. P, small spiral springs
placed in each hole of the case _q q_, _fig._ 570. They serve the
purpose of bringing back to its primitive position, every corresponding
needle, as soon as it ceases to press upon it.

[Illustration: 572 573]

_Fig._ 572. represents the plan of the upper row of horizontal needles.
_Fig._ 573. is a fragment of the endless chain, formed with perforated
cards, which are made to circulate or travel by the rotation of the
shaft D. In this movement, each of the perforated cards, whose position,
form, and number, are determined by the operation of tying-up of the
warp, comes to be applied in succession against the four faces of the
square axis or drum, leaving open the corresponding holes, and covering
those upon the face of the axis, which have no corresponding holes upon
the card.

Now let us suppose that the _press_ B is let down into the vertical
position shown in _fig._ 568.; then the card applied against the left
face of the axis, leaves at rest or untouched the whole of the
horizontal spindles (skewers), whose ends correspond to these holes, but
pushes back those which are opposite to the unpierced part of the card;
thereby the corresponding upright skewers, 3. 5. 6. and 8. for example,
pushed out of the perpendicular, unhook themselves from above the bars
of the claw, and remain in their place, when this claw comes to be
raised by means of the lever G; and the skewers 1. 2. 4. and 7., which
have remained hooked on, are raised along with the warp threads attached
to them. Then by the passage across of a shot of the colour, as well as
a shot of the common weft, and a stroke of the lay after shedding the
warp and lowering the press B, an element or point in the pattern is
completed.

The following card, brought round by a quarter revolution of the axis,
finds all the needles in their first position, and as it is necessarily
perforated differently from the preceding card, it will lift another
series of warp threads; and thus in succession for all the other cards,
which compose a complete system of a figured pattern.

This machine, complicated in appearance, and which requires some pains
to be understood, acts however in a very simple manner. Its whole play
is dependent upon the movement of the lever G, which the weaver himself
causes to rise and fall, by means of a peculiar pedal; so that without
the aid of any person, after the piece is properly read in and mounted,
he can execute the most complex patterns, as easily as he could weave
plain goods; only attending to the order of his weft yarns, when these
happen to be of different colours.

If some warp yarns should happen to break without the weaver observing
them, or should he mistake his coloured shuttle yarns, which would so
far disfigure the pattern, he must undo his work. For this purpose, he
makes use of the lower hooked lever _f´_, whose purpose is to make the
chain of the card go backwards, while working the loom as usual,
withdrawing at each stroke the shot both of the ground and of the
figure. The weaver is the more subject to make mistakes, as the figured
side of the web is downwards, and it is only with the aid of a bit of
looking-glass that he takes a peep of his work from time to time. The
upper surface exhibits merely loose threads in different points,
according as the pattern requires them to lie upon the one side or the
other.

Thus it must be evident, that such a number of paste-boards are to be
provided and mounted as equal the number of throws of the shuttle
between the beginning and end of any figure or design which is to be
woven; the piercing of each paste-board individually, will depend upon
the arrangement of the lifting rods, and their connection with the warp,
which is according to the design and option of the workman; great care
must be taken that the holes come exactly opposite to the ends of the
needles; for this purpose two large holes are made at the ends of the
paste-boards, which fall upon conical points, by which means they are
made to register correctly.

It will be hence seen, that, according to the length of the figure, so
must be the number of paste-boards, which may be readily displaced so as
to remount and produce the figure in a few minutes, or remove it, or
replace it, or preserve the figure for future use. The machine, of
course, will be understood to consist of many sets of the lifting rods
and needles, shown in the diagram, as will be perceived by observing the
disposition of the holes in the paste-board; those holes, in order that
they may be accurately distributed, are to be pierced from a gauge, so
that not the slightest variation shall take place.

To form these card-slips, an ingenious apparatus is employed, by which
the proper steel punches required for the piercing of each distinct
card, are placed in their relative situations preparatory to the
operation of piercing, and also by its means a card may be punched with
any number of holes at one operation. This disposition of the punches is
effected by means of rods connected to cords disposed in a frame, in the
nature of a false simple, on which the pattern of the work to be
performed is first read in.

These improved pierced cards, slips, or paste-boards, apply to a weaving
apparatus, which is so arranged that a figure to be wrought can be
extended to any distance along the loom, and by that means the loom is
rendered capable of producing broad figured works; having the long lever
G placed in such a situation that it affords power to the foot of the
weaver, and by this means enables him to draw the heaviest morintures
and figured works, without the assistance of a draw-boy.

The machinery for arranging the punches, consists of a frame with four
upright standards and cross-pieces, which contains a series of endless
cords passing under a wooden roller at bottom, and over pulleys at the
top. These pulleys are mounted on axles in two frames, placed obliquely
over the top of the standard frame, which pulley-frames constitute the
table commonly used by weavers.

[Illustration: 574]

In order better to explain these endless cords, _fig._ 574. represents a
single endless cord 1, 1, which is here shown in operation, and part of
another endless cord 2, 2, shown stationary. There must be as many
endless cords in this frame as needles in the weaving-loom. _a_ is the
wooden cylinder, revolving upon its axis at the lower part of the
standards; _b b_, the two pulleys of the pulley-frames above, over which
the individual endless cord passes; _c_ is a small traverse ring. To
each of these rings a weight is suspended by a single thread, for the
purpose of giving tension to the endless cord. _d_ is a board resembling
a common comber-bar, which is supported by the cross-bars of the
standard frame, and is pierced with holes, in situation and number,
corresponding with the perpendicular threads that pass through them;
which board keeps the threads distinct from each other.

At _e_, the endless cord passes through the eyes of wires resembling
needles, which are contained in a wooden box placed in front of the
machine, and shown in this figure in section only. These wires are
called the _punch-projectors_; they are guided and supported by
horizontal rods and vertical pins, the latter of which pass through
loops formed at the hinder part of the respective wires. At _f_ are two
horizontal rods extending the whole width of the machine, for the
purpose of producing the cross in the cords; _g_ is a thick brass plate,
extending along in front of the machine, and lying close to the box
which holds the _punch-projectors_; this plate _g_, shown also in
section, is called the _punch-holder_; it contains the same number of
apertures as there are punch-projectors, and disposed so as to
correspond with each other. In each of these apertures, there is a punch
for the purpose of piercing the cards, slips, or pasteboards with holes;
_h_ is a thick steel plate of the same size as _g_, and shown likewise
in section, corresponding also in its number of apertures, and their
disposition, with the punch-projectors and the punch-holder. This plate
_h_, is called the _punch-receiver_.

The object of this machine is to transfer such of the punches as may be
required for piercing any individual card from the punch-holder _g_,
into the punch-receiver _h_; when they will be properly situated, and
ready for piercing the individual card or slip, with such holes as have
been read in upon the machine, and are required for permitting the warp
threads to be withdrawn in the loom, when this card is brought against
the ends of the needles. The process of transferring the patterns to the
punches will be effected in the following manner.

The pattern is to be read in, according to the ordinary mode, as in a
false simple, upon the endless cords below the rods _f_, and passed
under the revolving wooden cylinder _a_, to a sufficient height for a
person in front of the machine to reach conveniently. He there takes the
upper threads of the pattern, called the _beard_, and draws them forward
so as to introduce a stick behind the cords thus advanced, as shown by
dots, for the purpose of keeping them separate from the cords which are
not intended to be operated upon. All the punch-projectors which are
connected with the cords brought forward, will be thus made to pass
through the corresponding apertures of the punch-holder _g_, and by this
means will project the punches out of these apertures, into
corresponding apertures of the punch-receiver _h_. The punches will now
be properly arranged for piercing the required holes on a card or slip,
which is to be effected in the following manner.

Remove the punch-receivers from the front of the machine; and having
placed one of the slips of card or pasteboard between the two folding
plates of metal, completely pierced with holes corresponding to the
needles of the loom, lay the punch-receiver upon those perforated
plates; to which it must be made to fit by mortises and blocks, the
cutting parts of the punches being downwards. Upon the back of the
punch-receiver is then to be placed a plate or block, studded with
perpendicular pins corresponding to the above described holes, into
which the pins will fall. The plates and the blocks thus laid together,
are to be placed under a press, by which means the pins of the block
will be made to pass through the apertures of the punch-receiver; and
wherever the punch has been deposited in the receiver by the above
process, the said punches will be forced through the slip of pasteboard,
and pierced with such holes as are required for producing the figured
design in the loom.

Each card being thus pierced, the punch-receiver is returned to its
place in front of the machine, and all the punches forced back again
into the apertures of the punch-holder as at first. The next set of
cords is now drawn forward by the next _beard_, as above described,
which sends out the _punch-projectors_ as before, and disposes the
punches in the punch-receiver, ready for the operation of piercing the
next card. The process being thus repeated, the whole pattern is, by a
number of operations, transferred to the punches, and afterwards to the
cards or slips, as above described.


JADE; axe-stone; (_Nephrite_, _Ceraunite_, Fr.) is a mineral commonly of
a greenish colour, compact, and of a fatty lustre. Spec. grav. 2·95;
scratches glass, is very tough; fuses into a white enamel. Its
constituents are, silica 50·5; alumina 10; magnesia 31; oxide of iron
5·50; oxide of chrome 0·05; water 2·75. It comes from China, is used
among rude nations for making hatchets; and is susceptible of being cut
into any form.


JAPANNING, is a kind of varnishing or lacquering, practised with
excellence by the Japanese, whence the name. See VARNISH.


JASPER; (_Jaspe calcedoine_, Fr.; _Jaspis_, Germ.) is a sub species of
calcedony quartz, of which there are five varieties. 1. The Egyptian red
and brown, with ring or tendril-shaped delineations. 2. Striped jasper.
3. Porcelain jasper. 4. Common jasper. 5. Agate jasper. The prettiest
specimens are cut for seals, and for the inferior kinds of jewellery
ornaments. See LAPIDARY.


ICEHOUSE; (_Glacière_, Fr.; _Eishaus_, Germ.) Under the article
FREEZING, I have enumerated the different artificial methods of
producing cold. But for the uses of common life, in these climates, the
most economical and convenient means of refrigeration in hot weather may
be procured by laying up a store of ice in winter, in such circumstances
as will preserve it solid during summer.

An icehouse should not be regarded as an object of mere luxury, for
pleasing the palates of gourmands with iced creams and orgeats. In the
southern countries of Europe it is considered among people in easy
circumstances as an indispensable appendage to a country mansion. During
the Dog-days, especially at those periods, and in those districts where
the _sirocco_ blows, a lassitude and torpor of mind and body supervene,
with indigestion or total loss of appetite, and sometimes dysenteries,
which are obviously occasioned by the excessive heat, and are to be
prevented or counteracted chiefly by the use of cold beverages. By
giving tone to the stomach, iced drinks immediately restore the
functions of the nervous and muscular systems when they are languid;
while they enable persons in health to endure without much inconvenience
an atmosphere so close and sultry as would be intolerable without this
remedy. Icehouses, moreover, afford to country gentlemen, a great
advantage in enabling them to preserve their fish, butcher meat, dead
poultry, and game, which would otherwise, in particular states of the
weather, immediately spoil. Considering at how little expense and
trouble an icehouse can be constructed, it is surprising that any
respectable habitation in the country should not have one attached to
it. The simplest and most scientific form is a double cone, that is, two
cones joined base to base; the one being of stones or brickwork, sunk
under ground with its apex at the bottom, into which the ice is rammed;
the other being a conical roof of carpentry covered with thatch, and
pointed at top. The entrance should be placed always on the north side;
it should consist of a corridor or porch with double doors, and be
screened from the sunbeams by a small shrubbery. Such are, in general,
the principles upon which an icehouse should be formed; but they will be
better understood by the following explanation and figure.

A dry sandy soil should be selected, and, if possible, a spot sheltered
by a cliff or other natural barrier from the direct rays of the sun.
Here a cavity is to be dug about 16 feet in diameter, terminating below
like the point of a sugar loaf. Its ordinary depth, for a moderate
family, may be about 24 feet; but the larger its dimensions are, the
longer will it preserve the ice, provided it be filled. In digging, the
workman should slope the ground progressively towards the axis of the
cone, to prevent the earth falling in. This conical slope should be
faced with brick or stone work about one foot thick, and jointed with
Roman cement so as to be air and water tight. A well is to be excavated
at the bottom two feet wide and four deep, covered at top with an iron
grating for supporting the ice, and letting the water drain away.

The upper cone may likewise be built of brickwork, and covered with
thatch; such a roof would prove the most durable. This is the
construction shown in _fig._ 575. Whatever kind of roof be preferred,
there must be left in it an oblong passage into the interior. This porch
should face the north, and be at least 8 feet long by 2-1/2 feet wide;
and perfectly closed by a well-fitted door at each end. All round the
bottom of this conical cover, a gutter should be placed to carry off the
rain to a distance from the icehouse, and prevent the circumjacent
ground from getting soaked with moisture.

[Illustration: 575]

_Fig._ 575. shows the section of a well-constructed icehouse. Under the
ice-chamber A the ice is rammed into the space B. C is the grate of the
drain-sink D. The portion E E is built in brick or stone; the base L of
the ice-chamber slopes inwards towards the centre at C. The upper part
of the brickwork E E is a little way below the level of the ground. The
wooden frame work F F F F forms the roof, and is covered with thick
thatch. G H is the wooden work of the door I. At K the bucket is seen
for lifting up a charge of ice, by means of the cord J passing over the
pulley M, which enables the servant to raise it easily.

The icehouse should have no window to admit light; but be, so to speak,
hermetically sealed in every point, except at its cess-pool, which may
terminate in a water trap to prevent circulation of air.

A clear day should be selected for charging the icehouse; but before
beginning to fill, a quantity of long dry straw should be laid on the
bottom crosswise; and as the ice is progressively introduced, straw is
to be spread against the conical sides, to prevent the ice from coming
into contact with the brick or stone work. The more firmly compacted the
ice is, the better does it keep; with which view it should be broken
into pieces with mallets before being thrown in. No layers of straw
should be stratified among the ice, for they would make its body porous.
Some persons recommend to pour in a little water with the successive
layers of ice, in order to fill up its small crevices, and convert the
whole into one mass.

Over the top layer a thick bed of straw should be spread, which is to be
covered with boards surmounted with heavy stones, to close up the
interstices in the straw. The inner and outer doors should never be
opened at once; but the one should always be shut before the other is
opened.

Dry snow well rammed keeps equally well with hard ice, if care be taken
to leave no cavities in the mass, and to secure its compactness by
sprinkling a little water upon the successive charges.

To facilitate the extraction of the ice, a ladder is set up against its
sloping wall at one side of the door, and left there during the season.


JELLY, VEGETABLE, of ripe currants and other berries, is a compound of
mucilage and acid, which loses its power of gelatinizing by prolonged
ebullition.


JELLY, ANIMAL; see GELATINE, GLUE, and ISINGLASS.


JET; (_Jaiet_ or _jais_, Fr.) a species of pitch-coal or glance-coal,
which, being found abundantly in a beautiful compact form, in the valley
of Hers, arrondissement of Pamiers, department of the Arriège, has been
worked up extensively there from time immemorial, into a multitude of
ornamental articles. With this black lignite, buttons, crosses,
rosaries, necklaces, ear-drops, bracelets, waist-buckles, &c. are made,
which were at one time much worn by ladies for mourning dresses. The
greater number of these ornaments are fashioned upon grindstones which
turn in a horizontal direction, and are kept continually wet; others are
turned at the lathe, or shaped by files.

About 40 years ago this manufacture employed from 1000 to 1200
operatives; at present it gives bread to only 60. This falling off may
be ascribed to the successful imitation of the jet articles by those of
black glass, which are equally beautiful, and not nearly so apt to lose
their polish by use.


IMPERMEABLE, is the epithet given to any kind of textile fabric,
rendered water-proof by one or other of the following substances:--

1. Linseed oil to which a drying quality has been communicated by
boiling with litharge or sugar of lead, &c.

2. The same oil holding in solution a little caoutchouc.

3. A varnish made by dissolving caoutchouc in rectified petroleum or
naphtha, applied between two surfaces of cloth, as described under
Macintosh’s patent. See CAOUTCHOUC.

4. Vegetable or mineral pitch, applied hot with a brush, as in making
tarpauling for covering goods in ships.

5. A solution of soap worked into cloth, and decomposed in it by the
action of a solution of alum; whence results a mixture of acid fats and
alumina, which insinuates itself among all the woolly filaments, fills
their interstices, and prevents the passage of water.

6. A solution of glue or isinglass, introduced into a stuff, and then
acted upon by a clear infusion of galls, whereby the fibres get
impregnated with an insoluble, impermeable, pulverulent leather.

7. Plaster work is rendered impermeable by mixing artificial or natural
asphaltum with it.


JEWELLERY, _Art of_. See GEM and LAPIDARY.


INCOMBUSTIBLE CLOTH; is a tissue of the fibrous mineral called amianthus
or asbestos. This is too rare to form the object of any considerable
manufacture. Cotton and linen cloth may be best rendered incapable of
taking fire, or burning with flame, by being imbued with a solution of
sal ammoniac.


INCUBATION, ARTIFICIAL. The Egyptians have from time immemorial been
accustomed to hatch eggs by artificial warmth, without the aid of hens,
in peculiar stoves, called _Mammals_. The inhabitants of the village
Bermé, still travel through the most distant provinces of Egypt at
certain seasons of the year, with a portable furnace, heated by a lamp,
and either hatch chickens for sale, or undertake to hatch the eggs
belonging to the natives at a certain rate per dozen. M. de Reaumur
published in France about a century ago, some ingenious observations
upon this subject; but M. Bonnemain was the first person who studied
with due attention all the circumstances of artificial incubation, and
mounted the process successfully upon the commercial scale. So far back
as 1777 he communicated to the Academy of Sciences an interesting fact,
which he had noticed, upon the mechanism employed by chicks to break
their shells; and for some time prior to the French revolution he
furnished the Parisian market with excellent poultry at a period of the
year when the farmers had ceased to supply it. His establishment was
ruined at that disastrous era, and no other has ever since been
constructed or conducted with similar care. As there can be no doubt
however of the practicability and profitableness of the scheme, when
judiciously managed, I shall insert a brief account of his ingenious
arrangements. I had the pleasure of making the acquaintance of this
amiable old man at my first visit to Paris, many years ago, and believe
all his statements to be worthy of credit. Some imitations of his plans
have been made in this country, but how far they have succeeded in an
economical point of view, it is difficult to determine. His apparatus
derives peculiar interest from the fact, that it was founded upon the
principle of the circulation of hot water, by the intestine motions of
its particles, in a returning series of connected pipes; a subject
afterwards illustrated in the experimental researches of Count Rumford.
It has of late years been introduced as a _novelty_ into this country,
and applied to warm the apartments of many public and private buildings.
The following details will prove that the theory and practice of
hot-water circulation were as perfectly understood by M. Bonnemain fifty
years ago, as they are by any of our stove-doctors at the present day.
They were then publicly exhibited at his residence in Paris, and were
afterwards communicated to the world at large in the interesting article
of the _Dictionnaire Technologique_, intitled _Incubation Artificielle_.

The apparatus of M. Bonnemain consisted: 1. of a boiler and pipes for
the circulation of water; 2. of a regulator calculated to maintain an
equable temperature; 3. of a stove-apartment, heated constantly to the
degree best fitted for incubation, which he called the _hatching_ pitch.
He attached to one side a _poussinière_ or chick-room, for cherishing
the chickens during a few days after incubation.

[Illustration: 576 577]

The boiler is represented in vertical section and ground plan, in
_figs._ 576. and 577. It is composed of a double cylinder of copper or
cast-iron _l_, _l_, having a grate _b_ (see plan), an ashpit at _d_
(section). The water occupies the shaded space C, C. _h_, _g_, _g_, _e_,
_e_, are five vertical flues, for conducting the burnt air and smoke,
which first rise in the two exterior flues _e_, _e_, then descend in the
two adjoining flues _g_, _g_, and finally re-mount through the passages
_i_, _i_, in the central flue _h_. During this upwards and downwards
circulation, as shown by the arrows in the section, the products of
combustion are made to impart nearly the whole of their heat to the
water by which they are surrounded. At the commencement, some burning
paper or wood shavings are inserted at the orifice _m_, to establish a
draught in this circuitous chimney. The air is admitted into the ash-pit
at the side, in regulated quantities, through a small square door,
movable round a rod which runs horizontally along its middle line. This
swing valve is acted upon by an expanding bar (see HEAT-REGULATOR),
which opens it more or less, according to the temperature of the stove
apartment in which the eggs are placed.

[Illustration: 578]

D is the upper orifice of the boiler, by which the hotter and
consequently lighter particles of the water continually ascend, and are
replaced by the cooled particles, which enter the boiler near its
bottom, as shown in _fig._ 578. at R. Into further details relative to
the boiler it is needless to enter; for though its form, as designed by
M. Bonnemain, is excellent and most economical of heat for a charcoal
fire, it would not suit one of pit-coal, on account of the obstruction
to the pipes which would soon be occasioned by its soot.

In _fig._ 578. the boiler is shown at R, with the rod which regulates
the air door of the ash-pit. D is a stopcock for modifying the opening
by which the hotter particles of water ascend; G is the water-pipe of
communication, having the heating pipe of distribution attached between
E F, which thence passes backwards and forwards with a very slight slope
from the horizontal direction, till it reaches the _poussinière_ O P Q.
It traverses this apartment, and returns by N N to the orifice of the
boiler H, where it turns vertically downwards, and descends to nearly
the bottom of the boiler, discharging at that point the cooled and
therefore denser particles of water to replace those which continually
issue upwards at D. L R is a tube surmounted with a funnel for keeping
the range of pipes always full of water; and K is a syphon orifice for
permitting the escape of the disengaged air, which would otherwise be
apt to occupy partially the pipes and obstruct the aqueous circulation.

The faster the water gets cooled in the serpentine tubes, the quicker
its circulation will be, because the difference of density between the
water at the top and bottom of the boiler, which is the sole cause of
its movement, will be greater. N represents small saucers filled with
water, to supply the requisite moisture to the heated air, and to place
the eggs, arranged along the trays M M, in an atmosphere analogous to
that under the body of the hen.

When we wish to hatch eggs with this apparatus, the fire is to be
kindled in the boiler, and as soon as the temperature has risen to about
100° F., the eggs are introduced; but only one-twentieth of the whole
number intended, upon the first day; next day, a like number is laid
upon the trays, and thus in succession for twenty days, so that upon the
twenty-first day the eggs first placed may be hatched for the most part,
and we may obtain daily afterwards an equal number of chicks. In this
way, regularity of care is established in the rearing of them.

During the first days of incubation, natural as well as artificial, a
small portion of the water contained in the egg evaporates by the heat,
through the shell, and is replaced by a like quantity of air, which is
afterwards useful for the respiration of the animal. If the warm
atmosphere surrounding the eggs were very dry, such a portion of the
aqueous part of the eggs would evaporate through the pores of the
shells, as would endanger the future life of the chick _in ovo_. The
transpiration from the body of the hen, as she sits upon her eggs,
counteracts this desiccation in general; yet in very dry weather, many
hatching eggs fail from that cause, unless they be placed in moist
decomposing straw. The water saucers N N are therefore essential to
success in artificial incubation.

After the chickens are hatched they are transferred into the nursery, O
Q, on the front side of which there is a small grated trough filled with
millet seed. Small divisions are made between the broods of successive
days, to enable the superintendent to vary their feeding to their age.

In order to supply an establishment of the common kind, where 100 eggs
are to be hatched daily, a dozen of hens would be needed, and 150 eggs
must be placed under them, as only two-thirds in general succeed. At
this rate, 4300 mothers would be required to sit. Now supposing we
should collect ten times as many hens, or 43,000, we should not be able
to command the above number of chickens, as there is seldom a tenth part
of hens in a brooding state. Besides, there would be in this case no
fewer than 720 hens every day coming out with a fresh brood of chickens,
which would require a regiment of superintendents.

_Artificial Incubation, by means of Hot Mineral Waters._--This curious
process is described very briefly in a letter by M. D’Arcet. The
following are extracts from this letter:--

“In June, 1825, I obtained chickens and pigeons at Vichy, by artificial
incubation, effected through the means of the thermal waters of that
place. In 1827 I went to the baths of Chaudes-Aigues, principally for
the purpose of doing the same thing there. Finding the proprietor a
zealous man, I succeeded in making a useful application of this source
of heat to the production of poultry.

“The advantage of this process may be comprehended, when it is known
that the invalids who arrive at Vichy, for instance in the month of May,
find chickens only the size of quails; whereas, by this means, they may
be readily supplied six months old.

“The good which may be done by establishing artificial incubation in
places where hot springs exist, is _incalculable_; it may be introduced
into these establishments without at all interfering with the medical
treatment of patients, since the hatching would go on in winter, at a
time when the baths for other purposes are out of use.

“There is no other trouble required in breeding chickens, by means of
hot baths, than to break the eggs at the proper time; for, when the
apartments are closed, the whole of the interior will readily acquire a
sufficiently elevated and very constant temperature.”

In addition to these details by M. D’Arcet, a letter was received from
M. Felgeris, the proprietor of the baths at Chaudes-Aigues (Cantal), in
which he describes the success he had in following M. D’Arcet’s process.
This consists in putting the eggs into a small basket, suspending it in
one of the stove-rooms heated by the hot mineral water, and turning
round the eggs every day. The very first trial was attended with
success, and no failure was experienced in four repetitions of it.


INDIGO. This invaluable blue dye-stuff, for which no tolerable
substitute has been found, was known to the ancients as a pigment under
the name of _indicum_, whence its present denomination. In modern
Europe, it first came into extensive use in Italy, but, about the middle
of the 16th century, the Dutch began to import and employ it in
considerable quantities. Its general introduction into the dye-houses of
both England and France was kept back by absurd laws, founded upon an
opinion that it was a fugitive substance, and even prejudicial to the
fibre of wool. See DYEING, p. 413.

The plants which afford this dye-drug grow in the East and West Indies,
in the middle regions of America, in Africa, and Europe. They are all
species of the genera _Indigofera_, _Isatis_, and _Nerium_.

The following are cultivated:--_Indigofera tinctoria_ affords in Bengal,
Malabar, Madagascar, the Isle of France, and St. Domingo, an article of
middling quality, but in large quantity. The _indigofera disperma_, a
plant cultivated in the East Indies and America, grows higher than the
preceding, is woody, and furnishes a superior dye-stuff. The Guatimala
indigo comes from this species. _Indigofera Anil_ grows in the same
countries, and also in the West Indies. The _Indigofera Argentea_, which
grows also in Africa; it yields little indigo, but of an excellent
quality. _Indigofera Pseudotinctoria_, which is cultivated in the East
Indies, furnishes the best of all: the _Indigofera Glauca_ is the
Egyptian and Arabian species. There are also the _cærulea_, _cinerea
erecta_, _hirsuta_, _glabra_, and several others. The _Nerium
tinctorium_ of the East Indies affords some indigo; as does the _Isatis
tinctoria_, or Woad, in Europe; and the _Polygonum tinctorium_.

The districts of Kishenagar, Jessore, and Moorshedabad, in Bengal,
ranging from 88° to 90° E.L. and 22-1/2° to 24° N.L., produce the finest
indigo. That from the districts about Burdwan and Benares is of a
coarser or harsher grain. Tyroot, in lat. 26°, yields a tolerably good
article. The portion of Bengal most propitious to the cultivation of
indigo lies between the river Hoogly and the main stream of the Ganges.

In the East Indies, after having ploughed the ground in October,
November, and the beginning of December, they sow the seed of the indigo
plant in the last half of March and the beginning of April, while the
soil being neither too hot nor too dry, is most propitious to its
germination. A light mould answers best; and sunshine, with occasional
light showers, are most favourable to its growth. Twelve pounds of seeds
are sufficient for sowing an acre of land. The plants grow rapidly, and
will bear to be cut for the first time at the beginning of July, nay, in
some districts, so early as the middle of June. The indications of
maturity are the bursting forth of the flower buds, and the expansion of
the blossoms; at which period the plant abounds most in the dyeing
principle. Another indication is taken from the leaves; which, if they
break across, when doubled flat, denote a state of maturity. But this
character is somewhat fallacious, and depends upon the poverty or
richness of the soil. When much rain falls, the plants grow too rapidly,
and do not sufficiently elaborate the blue pigment. Bright sunshine is
most advantageous to its production.

The first cropping of the plants is the best; after two months a second
is made; after another interval, a third, and even a fourth; but each of
these is of diminished value. There are only two croppings in America.

Two methods are pursued to extract the indigo from the plant; the first
effects it by fermentation of the fresh leaves and stems; the second, by
maceration of the dried leaves; the latter process being most
advantageous.

1. _From the recent leaves._--In the indigo factories of Bengal, there
are two large stone-built cisterns, the bottom of the first being nearly
upon a level with the top of the second, in order to allow the liquid
contents to be run out of the one into the other. The uppermost is
called the fermenting vat, or the steeper; its area is 20 feet square,
and its depth 3 feet; the lowermost, called the beater or beating vat,
is as broad as the other, but one third longer. The cuttings of the
plant, as they come from the field, are stratified in the steeper, till
this be filled within 5 or 6 inches of its brim. In order that the
plant, during its fermentation, may not swell and rise out of the vat,
beams of wood and twigs of bamboo are braced tight over the surface of
the plants, after which water is pumped upon them till it stands within
three or four inches of the edge of the vessel. An active fermentation
speedily commences, which is completed within 14 or 15 hours; a little
longer or shorter, according to the temperature of the air, the
prevailing winds, the quality of the water, and the ripeness of the
plants. Nine or ten hours after the immersion of the plant, the
condition of the vat must be examined; frothy bubbles appear, which rise
like little pyramids, are at first of a white colour, but soon become
gray-blue; and then deep purple-red. The fermentation is at this time
violent, the fluid is in constant commotion, apparently boiling,
innumerable bubbles mount to the surface, and a copper-coloured dense
scum covers the whole. As long as the liquor is agitated, the
fermentation must not be disturbed; but when it becomes more tranquil,
the liquor is to be drawn off into the lower cistern. It is of the
utmost consequence not to push the fermentation too far, because the
quality of the whole indigo is deteriorated; but rather to cut it short,
in which case there is, indeed, a loss of weight, but the article is
better. The liquor possesses now a glistening yellow colour, which, when
the indigo precipitates, changes to green. The average temperature of
the liquor is commonly 85° Fahr.; its specific gravity at the surface is
1·0015; and at the bottom 1·003.

As soon as the liquor has been run into the lower cistern, ten men are
set to work to beat it with oars, or shovels 4 feet long, called
_busquets_. Paddle wheels have also been employed for the same purpose.
Meanwhile two other labourers clear away the compressing beams and
bamboos from the surface of the upper vat, remove the exhausted plant,
set it to dry for fuel, clean out the vessel, and stratify fresh plants
in it. The fermented plant appears still green, but it has lost three
fourths of its bulk in the process, or from 12 to 14 per cent. of its
weight, chiefly water and extractive matter.

The liquor in the lower vat must be strongly beaten for an hour and a
half, when the indigo begins to agglomerate in flocks, and to
precipitate. This is the moment for judging whether there has been any
error committed in the fermentation; which must be corrected by the
operation of beating. If the fermentation has been defective, much froth
rises in the beating, which must be allayed with a little oil, and then
a reddish tinge appears. If large round granulations are formed, the
beating is continued, in order to see if they will grow smaller. If they
become as small as fine sand, and if the water clears up, the indigo is
allowed quietly to subside. Should the vat have been over fermented, a
thick fat-looking crust covers the liquor, which does not disappear by
the introduction of a flask of oil. In such a case the beating must be
moderated. Whenever the granulations become round, and begin to subside,
and the liquor clears up, the beating must be discontinued. The froth or
scum diffuses itself spontaneously into separate minute particles, that
move about the surface of the liquor; which are marks of an excessive
fermentation. On the other hand, a rightly fermented vat is easy to
work; the froth, though abundant, vanishes whenever the granulations
make their appearance. The colour of the liquor, when drawn out of the
steeper into the beater, is bright green; but as soon as the
agglomerations of the indigo commence, it assumes the colour of Madeira
wine; and speedily afterwards, in the course of beating, a small round
grain is formed, which, on separating, makes the water transparent, and
falls down, when all the turbidity and froth vanish.

The object of the beating is threefold: first, it tends to disengage a
great quantity of carbonic acid present in the fermented liquor;
secondly, to give the newly developed indigo its requisite dose of
oxygen by the most extensive exposure of its particles to the
atmosphere; thirdly, to agglomerate the indigo in distinct flocks or
granulations. In order to hasten the precipitation, lime-water is
occasionally added to the fermented liquor in the progress of beating,
but it is not indispensable, and has been supposed capable of
deteriorating the indigo. In the front of the beater a beam is fixed
upright, in which three or more holes are pierced a few inches in
diameter. These are closed with plugs during the beating, but, two or
three hours after it, as the indigo subsides, the upper plug is
withdrawn to run off the supernatant liquor, and then the lower plugs in
succession. The state of this liquor being examined, affords an
indication of the success of both the processes. When the whole liquor
is run off, a labourer enters the vat, sweeps all the precipitate into
one corner, and empties the thinner part into a spout which leads into a
cistern, alongside of a boiler, 20 feet long, 3 feet wide and 3 deep.
When all this liquor is once collected, it is pumped through a bag for
retaining the impurities, into the boiler, and heated to ebullition. The
froth soon subsides, and shows an oily looking film upon the liquor. The
indigo is by this process not only freed from the yellow extractive
matter, but is enriched in the intensity of its colour, and increased in
weight. From the boiler the mixture is run, after two or three hours,
into a general receiver called the _dripping vat_, or table, which, for
a factory of twelve pairs of preparation vats, is 20 feet long, 10 feet
wide, and 3 feet deep; having a false bottom, 2 feet under the top edge.
This cistern stands in a basin of masonry (made water tight with Chunam
hydraulic cement), the bottom of which slopes to one end, in order to
facilitate the drainage. A thick woollen web is stretched along the
bottom of the inner vessel, to act as a filter. As long as the liquor
passes through turbid, it is pumped back into the receiver. Whenever it
runs clear, the receiver is covered with another piece of cloth to
exclude the dust, and allowed to drain at its leisure. Next morning the
drained magma is put into a strong bag, and squeezed in a press. The
indigo is then carefully taken out of the bag, and cut with a brass wire
into bits, about 3 inches cube, which are dried, in an airy house, upon
shelves of wicker work. During the drying, a whitish efflorescence comes
upon the pieces, which must be carefully removed with a brush. In some
places, particularly on the coast of Coromandel, the dried indigo lumps
are allowed to effloresce in a cask for some time, and when they become
hard they are wiped and packed for exportation.

From some experiments it would appear that the gas disengaged during the
middle period of the fermentation is composed in 100 parts of 27·5
carbonic acid, 5·8 oxygen, and 66·7 azote; and towards its end, of 40·5
carbonic acid, 4·5 oxygen, and 55·0 azote. The fermenting leaves
apparently convert the oxygen of the atmosphere into carbonic acid gas,
and leave its azote; besides the quantity of carbonic acid which they
spontaneously evolve. Carburetted hydrogen does not seem to be
disengaged. That the liquor in the beating vat absorbs oxygen from the
air in proportion as the indigo becomes flocculent and granular, has
been ascertained by experiment, as well as that sunshine accelerates the
separation of the indigo blue. Out of 1000 parts of the fermented liquor
of specific gravity 1·003, the blue precipitate may constitute 0·75 of a
part. Such a proportion upon the great scale is however above the
average, which is not more than 0·5. When lime water is added, an
extractive matter is thrown down, which amounts to from 20 to 47 parts
in 1000 of the liquor. It has a dark brown tint, a viscid appearance, an
unpleasant smell, and a bitter taste. It becomes moist in damp air, and
dissolves in water without decomposition. It is precipitated by lime,
alkalis, infusion of galls, and acetate of lead. All indigo contains a
little lime derived from the plant, even though none has been used in
its preparation.

2. _Indigo from dried leaves._--The ripe plant being cropped, is to be
dried in sunshine from 9 o’clock in the morning till 4 in the afternoon,
during two days, and threshed to separate the stems from the leaves,
which are then stored up in magazines till a sufficient quantity be
collected for manufacturing operations. The newly dried leaves must be
free from spots, and friable between the fingers. When kept dry, the
leaves undergo in the course of 4 weeks, a material change, their
beautiful green tint turning into a pale blue-gray, previous to which
the leaves afford no indigo by maceration in water, but subsequently a
large quantity. Afterwards the product becomes less considerable.

The following process is pursued to extract indigo from the dried
leaves. They are infused in the steeping vat with six times their bulk
of water, and allowed to macerate for two hours with continual stirring
till all the floating leaves sink. The fine green liquor is then drawn
off into the beater vat, for if it stood longer in the steeper, some of
the indigo would settle among the leaves and be lost. Hot water, as
employed by some manufacturers, is not necessary. The process with dry
leaves possesses this advantage, that a provision of the plant may be
made at the most suitable times, independently of the vicissitudes of
the weather, and the indigo may be uniformly made; and moreover, that
the fermentation of the fresh leaves, often capricious in its course, is
superseded by a much shorter period of simple maceration.

The process for obtaining indigo from the _Nerium_ is altogether the
same, but hot water has been generally applied to the dried leaves. For
woad, hot water must be employed, and also lime water as a precipitant,
on account of the small proportion of indigo in the plant. Dilute
muriatic acid is digested upon the woad indigo to remove the lime,
without which no dye could be precipitated. According to the warmth of
the summer and the ripeness of the plant, from 2 to 5 ounces of indigo
may be obtained from 100 pounds of the dried woad, or upon an average 4
ounces to the hundred weight.

The indigo found in European commerce is imported from Bengal,
Coromandel, Madras, the Mauritius, Manilla, and Java in the Eastern
hemisphere; from Senegal, Caraccas, Guatimala, Brazil, (South Carolina
and Louisiana in small quantity), and formerly from the West India
islands, especially St. Domingo. Its quality depends upon the species of
the plant, its ripeness, the soil and climate of its growth, and mode of
manufacture. The East Indian and Brazilian indigo comes packed in
chests, the Guatimala in ox-hides, called _surons_.

The organ which affords the indigo is confined entirely to the pellicle
of the leaves, and exists in largest quantity at the commencement of
maturation while the plant is in flower. The indigofera is remarkable
for giving a blue tinge to the urine of cows that feed upon its leaves.

According to some manufacturers, the plants should be cut down in dry
weather, an hour or two before sunset, carried off the field in bundles,
and immediately spread upon a dry floor. Next morning the reaping is
resumed for an hour and a half, before the sun acts too powerfully upon
vegetation; and the plants are treated in the same way. Both cuttings
become sufficiently dry by three o’clock in the afternoon, so as to
permit the leaves to be separated from the stems by threshing. They are
now thoroughly dried in the sunshine, then coarsely bruised, or
sometimes ground to powder in a mill, and packed up for the operations
of manufacture.

In the spring of 1830 I subjected a variety of specimens of indigo to
comparative analyses, by dissolving a few grains of each in strong
sulphuric acid, diluting the solutions with an equal volume of water,
and determining the resulting shade of colour in a hollow prism of plate
glass, furnished with a graduated scale. The following are the results,
compared to the shade produced by a like weight of absolute indigo.

I. East India Indigos; prices as at the last October sales.

  +---+---------+----------+-------------------------------------------+
  |No.|  Price. |Real indi-|     Characters by the Brokers.            |
  |   |         |go in 100 |                                           |
  |   |         |parts.    |                                           |
  +---+---------+----------+-------------------------------------------+
  |   |_s._ _d._|          |                                           |
  | 1 | 3    9  |  42      |Broken, middling violet, and coppery violet|
  |   |         |          |spotted.                                   |
  | 2 | 3    6  |  56·5    |Ditto, a little being coppery violet and   |
  |   |         |          |copper.                                    |
  | 3 | 3    3  |  46·0    |Ditto, middling red violet, dull violet and|
  |   |         |          |lean.                                      |
  | 4 | 4    3  |  54·5    |Large broken, and square, even middling red|
  |   |         |          |violet.                                    |
  | 5 | 4    2  |  75·0    |Much broken and very small, very crumbly   |
  |   |         |          |and limy, soft, good violet.               |
  | 6 | 4    9  |  60·0    |Square and large broken, 1/2 middling      |
  |   |         |          |violet, and 1/2 good coppery violet.       |
  | 7 | 5    3  |  70·0    |Large broken, very good; paste a little    |
  |   |         |          |limy, good violet.                         |
  | 8 | 6    6  |  60·0    |Square and large broken, soft, fine paste, |
  |   |         |          |fine violet.                               |
  | 9 | 6    0  |  66-2/3  |Square, ditto, good red violet.            |
  |10 | 7    0  |  75      |Square, ditto, fine purple and blue.       |
  |11 | 2    3  |  37·5    |Middling ordinary Madras.                  |
  |12 | 3    6  |  60·0    |Good Madras.                               |
  |13 | 4    3  |  58·0    |Very fine ditto.                           |
  |14 | 2    0  |  ----    |Low, pale Oude.                            |
  |15 | 2    4  |  27-3/4  |Middling, ordinary Oude.                   |
  |16 | 3    3  |  54      |Good Oude.                                 |
  |17 | 1    9  |  29      |Lundy, very low quality.                   |
  +---+---------+----------+-------------------------------------------+

II. American Indigos; wholesale prices at present. (March 1830.)

  +------------+---+---------+-------+
  |            |   |         |Parts  |
  |  Indigo.   |No.|  Price. |in 100.|
  +------------+---+---------+-------+
  |            |   |_s._ _d._|       |
  |Caraca flor.| 1 | 6    0  |54-1/2 |
  |Guatimala   | 2 | 5    0  |33-1/2 |
  |   ----     | 3 | 3    2  |19     |
  |   ----     | 4 | 4    6  |32-1/2 |
  |   ----     | 5 | 5    4  |50     |
  |   ----     | 6 | 5    0  |50     |
  |   ----     | 7 | 5    3  |35     |
  |   ----     | 8 | 4    8  |46     |
  |   ----     | 9 | 4    8  |33-1/2 |
  |   ----     |10 | 5    4  |50     |
  +------------+---+---------+-------+

_Properties of Indigo._--It possesses a dark blue colour, passing into
violet-purple, is void of taste and smell, dull, but by rubbing with a
smooth hard body, it assumes the lustre and hue of copper. It occurs
sometimes less and sometimes more dense _apparently_ than water, which
circumstance depends upon its freedom from foreign impurities, as well
as upon the treatment of its paste in the boiling, pressing, and drying
operations. It is insoluble in water, cold alcohol, ether, muriatic
acid, dilute sulphuric acid, cold ethereous and fat oils; but boiling
alcohol and oils dissolve a little of it, which they deposit on cooling.
Creosote has the property of dissolving indigo.

Indigo is a mixture of several dye-stuffs, and other substances.
Berzelius found in it a matter resembling vegetable gluten or gliadine,
a brown, red, and blue pigment, besides oxide of iron, clay, lime,
magnesia, and silica.

1. Indigo gluten or gliadine is dissolved along with the calcareous and
magnesian salts by acids. If the powder be treated with dilute sulphuric
acid, if the solution be saturated with carbonate of lime, evaporated to
dryness, and its residuum treated with alcohol; the solution thus formed
leaves, after being evaporated, a yellow transparent extract, easily
soluble in water, more difficultly in acid liquids; showing that acids
extract only a portion of the gliadine from the indigo. It yields, by
dry distillation, much ammonia, a fetid oil, and comports itself in
other respects like vegetable gluten.

2. _Indigo-brown_, occurs in combination with lime, as also with
vegetable acid in considerable quantity, and more abundantly in the
coarser sorts of indigo than in the finer. Indigo purified by acids is
to be treated with hot strong caustic lye, which dissolves the
indigo-brown; the liquid part of the mixture passes with difficulty
through the filter, is black-brown, opaque, and holds some indigo-blue
in solution, or diffused in fine powder. The alkali being neutralized
with acetic acid, the liquor is to be evaporated, and alcohol poured on
the residuum, whereby the alkaline acetate is dissolved out from the
brown.

This pigment is a dark brown, almost black, but is not yet entirely
deprived of the other constituents of indigo. It is nearly tasteless, is
combustible, affords, by dry distillation, ammonia and fetid oil, forms
with acids combinations hardly soluble in water, with alkalis soluble
ones, but with earths hardly soluble. Lime possesses the property of
precipitating the indigo-brown completely from its alkaline solution.
Chlorine occasions a pale yellow brownish precipitate, which consists of
indigo brown and muriatic acid, but causes no further change. By drying,
it becomes again dark coloured. Indigo-brown seems to exist also in
woad.

3. _Indigo-red_, or more properly red resin of indigo. This may be
obtained by boiling alcohol of sp. grav. 0·830 upon some indigo which
has been previously treated with acids and alkalis; for the red
substance is hardly soluble in cold alcohol. The solution is dark red,
opaque, and leaves, by distillation, the indigo-red in the form of a
black-brown powder, or a glistening varnish, slightly soluble in alcohol
and ether. Alkalis do not dissolve it, but concentrated sulphuric acid
forms with it a dark yellow dye, from which water causes no
precipitation; wool extracts the colour from the acid solution, and
becomes of a dirty brown hue. Chlorine does not seem capable of
destroying the colour for though it makes it yellow, it becomes as dark
as ever on being dried. Indigo-red melts with heat, burns with a bright
flame, affords, when heated in vacuo, first a white crystalline
sublimate, and then unchanged indigo-red. That white matter is changed
by nitric acid into indigo-red.

4. _Indigo-blue_, or pure indigo remains, after treating the indigo of
commerce with dilute acid, alkalis, and alcohol; it retains, however,
still traces of the matters thereby extracted, along with some earthy
substances. In order to procure indigo-blue in its utmost purity, we
must deoxidize the above blue residuum, thus form colourless indigo,
which again acquires a blue colour from the air, and constitutes the
pure pigment. For this purpose the above moist indigo is to be mixed
with slaked lime, green sulphate of iron, and hot water in an air-tight
matrass. The indigo when deoxidized by protoxide of iron being soluble
in lime-water, the clear yellow solution is to be poured off, and
exposed to the air. The indigo absorbs oxygen, and becomes again blue.
By digestion with dilute muriatic acid the foreign matters are
dissolved, and may then be washed away with distilled water, from the
_absolute_ indigo.

The indigo-blue obtained in this manner has a cast of purple red,
displaying the characteristic copper lustre in a high degree, but in
powder, it is blue. It is void of taste and smell, is by my experiments
of specific gravity 1·50, affords at 554° Fahr. a purple vapour, and
sublimes in shining purple scales, or slender needles in an apparatus
open to the air, whereby, however, much of it is destroyed. Some carbon
remains after the sublimation. A quick heat produces most sublimate.
These needles contain a brown oily matter, which may be dissolved out by
means of hot alcohol. Their specific gravity is 1·35, according to Mr.
Crum. The sublimate from common indigo does not contain any oil, but
some indigo-red and the above white crystalline matter. According to Mr.
Crum, indigo-blue consists of carbon, 73·22; oxygen, 12·60; azote,
11·26; hydrogen, 2·92; while according to Dumas, crystallized indigo
consists of carbon, 73·26; oxygen, 10·43; azote, 13·81; and hydrogen,
2·50: precipitated indigo consists of carbon, 74·81; oxygen, 7·88;
azote, 13·98; and hydrogen, 3·33: sublimed indigo, of carbon, 71·71;
oxygen, 12·18; azote, 13·45; hydrogen, 2·66. My own analysis
afforded--carbon, 71·37; oxygen, 14·25; azote, 10·00; hydrogen, 4·33. In
another analysis of Dumas, 3·93 parts of hydrogen were obtained. Hence
we must infer that considerable differences exist in the composition of
indigo in its purest state. Reagents act upon it much as upon common
indigo. Chlorine, iodine, and bromine convert it into a reddish brown
soluble substance. Concentrated sulphuric acid, especially the smoking
or anhydrous of Nordhausen, dissolves indigo-blue with the disengagement
of heat, but it makes it suffer some modification; for though it retains
an intense dark blue colour, it has become soluble in water, and may be
blanched by light, which does not happen with indigo itself. Nitric acid
destroys indigo-blue, forms indigotic (carbazotic) acid, carbonic acid,
artificial resin, and bitter principle.

Indigo-blue may be reduced by substances oxidized, with the co-operation
of alkalis or alkaline earths; for example, by such substances as have a
strong affinity for oxygen, and are imperfectly saturated with this
principle, as the sulphurous and phosphorous acids and their salts, the
protoxides of iron and manganese, the protoxide salts of tin, and the
corresponding compounds of chlorine, as the proto-chlorides of tin and
iron; and the solution of the former in potash. When in these
circumstances, in the presence of alkali, a deoxidation or reduction of
the indigo-blue takes place, the other bodies get oxidized by absorption
of the oxygen of the indigo-blue; the protoxides become peroxides, and
the acids in _ous_ become acids in _ic_, &c. Several metallic sulphurets
also reduce the indigo-blue in the same predicament, as the sulphurets
of potassium, of calcium, of antimony, and of arsenic (orpiment). A
similar influence is exercised by fermenting vegetable substances, such
as woad, madder, bran, raw sugar (molasses), starch, syrup, in
consequence of the formation of carbonic and acetic acids, by absorption
of the oxygen of the indigo-blue, for acetic acid and acetic salts are
found in the liquor of the warm blue vat, in which indigo has been
reduced by means of woad, madder, and bran.

_Formation of colourless reduced indigo-blue, or indigotine._--Purified
indigo-blue is to be treated with copperas and slaked lime, as above
described; or the clear wine-yellow supernatant liquor of the cold
blue-vat mixture is to be taken, run by a syphon into a matrass, a few
drops of concentrated acetic or sulphuric acid, deprived of air, are to
be poured into it, and the vessel being made quite full, is to be well
corked. The reduced indigo soon falls in white flocks, or crystalline
scales. They must be edulcorated upon a filter with water deprived of
its air by boiling, then pressed between folds of blotting-paper, and
dried under the receiver in vacuo. Indigo-blue may likewise be reduced
and dissolved by solution of hydro-sulphuret of ammonia; and the
colourless indigotine may be precipitated by muriatic acid.

The reduced indigo is sometimes white at the instant of its elimination,
sometimes grayish, of a silky lustre, but becomes very readily greenish,
blue green, and blue, in the air; in which case it absorbs, according to
Berzelius, 4·2 per cent. of oxygen; but according to Liebig, 11·5 per
cent. It is void of taste and smell, is insoluble in water; well boiled
water free from air is not affected by it, but is turned blue by common
water. It dissolves in alcohol and ether into a yellow dye; not in
dilute acids, but in concentrated sulphuric acid, whereby probably a
portion of this is decomposed, and some hyposulphurous acid formed; the
colour of this solution is blue. Solutions of the caustic and carbonated
alkalis, even the alkaline earths, readily dissolve reduced indigo into
a wine-yellow liquid; but in contact with air, oxygen is absorbed, and
indigo-blue falls, while a purple-coloured froth, passing into
copper-red, appears upon the surface, just as in the indigo vats of the
dyer.

The reduced indigo may be combined, by means of complex affinity, with
other bases, with the exception of the oxides of copper, zinc, and
mercury, which oxidize it. These combinations are white, in part
crystallizable, become speedily blue in the air, and afford by
sublimation indigo-blue. Berzelius formed with lime a two-fold
combination; one easily soluble in water, and another difficultly
soluble, of a lemon colour, which contained an excess of lime; this is
formed both in the hot and the cold blue vat; in the latter it is
occasioned by an overdose of lime.

When pure indigo-blue is treated with concentrated sulphuric acid, and
particularly with six times its weight of the smoking _dry_ acid, it
dissolves completely, and several different compounds are produced in
the solution. There is first a blue sulphate of indigo; secondly, a
similar compound with the resulting hyposulphurous acid; thirdly, a
combination of sulphuric acid with the purple of indigo (called Phænicin
by Crum), a peculiar substance, generated from indigo-blue. These three
compounds are here dissolved in an excess of sulphuric acid. The more
concentrated the sulphuric acid is, the more blue hyposulphite is
formed. The solution in smoking acid, when diluted with water and
filtered, affords a considerable precipitate of indigo purple, which
that in oil of vitriol does not. The vapour of anhydrous sulphuric acid
combines with indigo-blue into a purple fluid.

In order to obtain from the dark blue solution each of these blue acids
in a pure state, we must dilute it with forty times its weight of water,
and immerse in the filtered liquor, well washed wool or flannel, with
which the blue acids combine, while most of the sulphuric acid and some
other foreign substances remain free in the liquor. The wool must be
then scoured with water containing about half a per cent. of carbonate
of ammonia, or potash, which neutralizes both of the blue acids, and
produces a blue compound. This being evaporated to dryness at the
temperature of 140° F., alcohol of 0·833 is to be poured upon the
residuum, which dissolves the blue hyposulphite, but leaves the blue
sulphate undissolved. From either salt, by precipitating with acetate of
lead, by acting upon the precipitate with sulphuretted hydrogen water,
and evaporation, either of the two blue acids may be obtained. They may
be both evaporated to dryness, especially the blue sulphate of indigo;
they both become somewhat moist in the air, they are very soluble in
water, and the blue sulphate also in alcohol; they have a not unpleasant
smell, and an acid astringent taste.

From these habitudes, particularly in reference to the bases, it appears
that indigo-blue does not comport itself like a saline base towards the
acids, but rather like an acid, since it enters into the salts, just as
the empyreumatic oil of vinegar and oil of turpentine do into resin
soaps. The blue pigment of both acids is reduced by zinc or iron without
the disengagement of hydrogen gas; as also by sulphuretted hydrogen,
tepid protochloride of tin, while the liquor becomes yellow.

_Indigo-blue sulphate of potash, or ceruleo-sulphate of potash_, may be
obtained by extracting the blue colour from the wool by water containing
1 per cent. of carbonate of potash, evaporating nearly to dryness,
treating the extract with alcohol to remove the _indigo-blue
hyposulphite_, then with acetic acid and alcohol to remove any excess of
carbonate of potash. It is found in commerce under the name of
precipitated indigo, indigo paste, blue carmine, and soluble indigo. To
prepare it economically, indigo is to be dissolved in ten times its
weight of concentrated sulphuric acid; the solution after twenty-four
hours is to be diluted with ten times its weight of water, filtered, and
imperfectly saturated with carbonate of potash; whereby a blue powder
falls down; for the resulting sulphate of potash throws down the
ceruleo-sulphate, while the hyposulphite of potash remains dissolved. It
is a dark blue copper shining powder, soluble in 140 parts of cold
water, and in much less of boiling water. It is made use of as a dye,
and to give starch a blue tint. When mixed with starch into cakes, it is
sold under the name of _blue_ for washerwomen.

Ceruleo-sulphate of ammonia may be formed in the same way. It is much
more soluble in water. Ceruleo-sulphate of lime is obtained by
saturating the above dilute acid with chalk, filtering to separate the
undyed gypsum, and washing with water till the purple colour be
extracted. This liquor evaporated and decomposed by alcohol, affords a
bluish flocky precipitate, which is more soluble in water than common
gypsum, and dries up in a purple-blue film. Ceruleo-sulphate of alumina
may be obtained by double affinity; it is dark blue while moist, but
becomes black-blue by drying, and is soluble in water.

The blue present in all these salts of _ceruline_ is destroyed by
sunshine, becomes greenish-gray by caustic alkalis; and turns
immediately yellow-brown by alkaline earths. But when the solution is
very dilute, the colour becomes first green, then yellow. The carbonates
of alkalis do not produce these changes. Nitric acid decomposes the
colour quickly. Mr. Crum considers ceruline to be a combination of
indigo-blue with water.

_Phenicine_, or indigo-purple combined with sulphuric acid, is obtained
when the solution of indigo-blue in concentrated sulphuric acid, has
been diluted for a few hours with water, and then filtered. It seems to
be an intermediate body into which the indigo-blue passes, before it
becomes soluble _ceruline_. Hence it occurs in greater quantity soon
after digesting the indigo with the acid, than afterwards. It is dark
blue, dissolves gradually in water, affords after evaporation a blue
residuum, of the same appearance as the above blue acids. When a salt is
added to it a purple precipitate ensues, which is a compound of
indigo-purple, sulphuric acid, and the base of the salt. Indigo-purple
is reduced by bodies having a strong attraction for oxygen, if a free
alkali or alkaline earth be present, and its solution is yellow, but it
becomes blue in the atmosphere. According to Mr. Crum, _Phenicine_
contains half as much combined water as ceruline.

The table which I published in 1830 (as given above) shows very clearly
how much the real quality and value of indigo differ from its reputed
value and price, as estimated from external characters by the brokers.
Various test or proof processes of this drug have been proposed. That
with chlorine water is performed as follows. It is known that chlorine
destroys the blue of indigo, but not the indigo-red or indigo-brown,
which by the resulting muriatic acid is thrown down from the sulphuric
solution in flocks, and the chlorine acts in the same way on the
gliadine or gluten of the indigo. Pure indigo-blue is to be dissolved in
10 or 12 parts of concentrated sulphuric acid, and the solution is to be
diluted with a given weight of water, as, for example, 1000 parts for 1
of indigo-blue. If we then put that volume of liquor into a graduated
glass tube, and add to it chlorine water of a certain strength till its
blue colour be destroyed by becoming first green and then red-brown, we
can infer the quantity of colour from the quantity of chlorine water
expended to produce the effect. The quantity of real indigo-blue cannot,
however, be estimated with any accuracy in this way, because the other
colouring matters in the drug act also upon the chlorine; and, indeed,
the indigo itself soon changes, when dissolved in sulphuric acid, even
out of access of light, while the chlorine water itself is very
susceptible of alteration. Perhaps a better appreciation might be made
by avoiding the sulphuric acid altogether, and adding the
finely-powdered indigo to a definite volume of the chlorine water till
its colour ceased to be destroyed, just as prussian-blue is decoloured
by solution of potash in making the ferro-cyanide.

Another mode, and one susceptible of great precision, is to convert 10
or 100 grains of indigo finely powdered into its deoxidized state, as in
the blue vat by the proper quantity of slaked lime and solution of green
sulphate; then to precipitate the indigo, collect and weigh it. The
indigo should be ground upon a muller along with the quicklime, the
levigated mixture should be diluted with water, and added to the
solution of the copperas. This exact analytical process requires much
nicety in the operator, and can hardly be practised by the broker,
merchant, or manufacturer.

_Employment of indigo in dyeing._--As indigo is insoluble in water, and
as it can penetrate the fibres of wool, cotton, silk, and flax, only
when in a state of solution, the dyer must study to bring it into this
condition in the most complete and economical manner. This is effected
either by exposing it to the action of bodies which have an affinity for
oxygen superior to its own, such as certain metals and metallic oxides,
or by mixing it with fermenting matters, or, finally, by dissolving it
in a strong acid, such as the sulphuric. The second of the above methods
is called the warm blue, or pastel vat; and being the most intricate, we
shall begin with it.

Before the substance indigo was known in Europe, woad having been used
for dyeing blue, gave the name of woad vats to the apparatus. The vats
are sometimes made of copper, at other times of iron or wood, the last
alone being well adapted for the employment of steam. The dimensions are
very variable; but the following may be considered as the average size:
depth, 7-1/2 feet; width below, 4 feet, above, 5 feet. The vats are
built in such a way that the fire does not affect their bottom, but
merely their sides half way up; and they are sunk so much under the
floor of the dyehouse, that their upper half only is above it, and is
surrounded with a mass of masonry to prevent the dissipation of the
heat. About 3 or 3-1/2 feet under the top edge an iron ring is fixed,
called the _champagne_ by the French, to which a net is attached in
order to suspend the stuffs out of contact of the sediment near the
bottom.

In mounting the vat the following articles are required: 1. woad
prepared by fermentation, or woad merely dried, which is better, because
it may be made to ferment in the vat, without the risk of becoming
putrid, as the former is apt to do; 2. indigo, previously ground in a
proper mill; 3. madder; 4. potash; 5. slaked quicklime; 6. bran. In
France, weld is commonly used instead of potash.

[Illustration: 579 580]

The indigo mill is represented in _figs._ 579. and 580. _a_ is a
four-sided iron cistern, cylindrical or rounded in the bottom, which
rests upon gudgeons in a wooden frame; it has an iron lid _b_,
consisting of two leaves, between which the rod _c_ moves to and fro,
receiving a vibratory motion from the crank _d_. By this construction, a
frame _e_, which is made fast in the cistern by two points _e´ e´_, is
caused to vibrate, and to impart its swing movement to six iron rollers
_f f f_, three being on each side of the frame, which triturate the
indigo mixed with water into a fine paste. Whenever the paste is
uniformly ground, it is drawn off by the stopcock _g_, which had been
previously filled up by a screwed plug, to prevent any of the indigo
from lodging in the orifice of the cock, and thereby escaping the action
of the rollers. The cistern is nearly three feet long.

The vat being filled with clear river water, the fire is to be kindled,
the ingredients introduced, and if fermented woad be employed, less lime
is needed than with the merely dried plant. Meanwhile the water is to be
heated to the temperature of 160° Fahr., and maintained at this pitch
till the deoxidizement and solution of the indigo begin to shew
themselves, which, according to the state of the constituents, may
happen in 12 hours, or not till after several days. The first characters
of incipient solution are blue bubbles, called the flowers, which rise
upon the surface, and remain like a head of soap-suds for a considerable
time before they fall; then blue coppery shining veins appear with a
like coloured froth. The hue of the liquor now passes from blue to
green, and an ammoniacal odour begins to be exhaled. Whenever the indigo
is completely dissolved, an acetic smelling acid may be recognized in
the vat, which neutralizes all the alkali, and may occasion even an acid
excess, which should be saturated with quicklime. The time for doing
this cannot be in general very exactly defined. When quicklime has been
added at the beginning in sufficient quantity, the liquor appears of a
pale wine-yellow colour, but if not, it acquires this tint on the
subsequent introduction of the lime. Experience has not hitherto decided
in favour of the one practice or the other.

As soon as this yellow colour is formed in the liquor, and its surface
becomes blue, the vat is ready for the dyer, and the more lime it takes
up without being alkaline, the better is its condition. The dyeing power
of the vat may be kept up during six months, or more, according to the
fermentable property of the woad. From time to time, madder and bran
must be added to it, to revive the fermentation of the sediment, along
with some indigo and potash, to replace what may have been abstracted in
the progress of dyeing. The quantity of indigo must be proportional, of
course, to the depth or lightness of the tints required.

During the operation of this blue vat two accidents are apt to occur;
the first, which is the more common one, is called the _throwing back_,
in French the _cuve rebuté_, and in German, the _Scharf_ or
_Schwartzwerden_ (the becoming sharp or black); the second is the
_putrefaction_ of the ingredients. Each is discoverable by its peculiar
smell, which it is impossible to describe. The first is occasioned by
the employment of too much quicklime, whereby the liquor becomes neutral
or even alkaline. This fault may be recognized by the fading of the
green, or by the dark green, or nearly black appearance of the liquor;
and by a dull blue froth, owing to a film of lime. The remedy for a
slight degree of this vicious condition, is to suspend in the liquor a
quantity of bran tied up in a bag, and to leave it there till the
healthy state be restored. Should the evil be more inveterate, a
decoction of woad, madder, and bran must be introduced. Strong acids are
rather detrimental. Sulphate of iron has been recommended, because its
acid precipitates the lime, while its oxide reduces the indigo to the
soluble state.

The decomposition or putrefaction of the blue vat is an accident the
reverse of the preceding, arising from the transition of the acetous
into the putrid fermentation, whereby the dyeing faculty is destroyed.
Such a misfortune can happen only towards the commencement of working
the vat, whilst the woad is still powerful, and very little indigo has
been dissolved. Whenever the vat is well charged with indigo, that
accident cannot easily supervene. In both of these distemperatures the
elevation of the temperature of the vat aggravates the evil.

Dyeing in the blue vat is performed as follows:--

Wool is put into a net, and pressed down into the liquor with rods; but
cloth is smoothly stretched and suspended by hooks upon frames, which
are steadily dipped into the vat, with slight motions through the
liquor; yarn-hanks must be dipped and turned about by hand. All
unnecessary stirring of the liquor must however be avoided, lest the
oxygen of the atmosphere be brought too extensively into contact with
the reduced indigo, for which reason mechanical agitation with rollers
in the vat is inadmissible. The stuffs to be dyed, take at the first dip
only a feeble colour, though the vat be strong, but they must be
deepened to the desired shade by successive immersions of fifteen
minutes or more each time, with intervals of exposure to the air, for
absorption of its oxygen.

After the lapse of a certain time, if the fermentative power be
impaired, which is recognized by the dye stuffs losing more colour in a
weak alkaline test lye than they ought, the vat should be used up as far
as it will go, and then the liquor should be poured away, for the indigo
present is not in a reduced state, but merely mixed mechanically, and
therefore incapable of forming a chemical combination with textile
fibres. If cotton goods previously treated with an alkaline lye are to
be dyed blue, the vat should contain very little lime.

_Theory of the Indigo vat._--The large quantity of extractive matter in
woad and madder; as also the sugar, starch and gluten in the bran and
woad, when dissolved in warm water, soon occasion a fermentation, with
an absorption of oxygen, from the air, but especially from the indigo of
the woad, and from that introduced in a finely ground state. When thus
disoxygenated, it becomes soluble in alkaline menstrua; the red-brown of
the indigo being dissolved at the same time. When lime is added, the
indigo-blue dissolves, and still more readily if a little potash is
conjoined with it; but whatever indigo-brown may have been dissolved by
the potash, is thrown down by the lime. Lime in too large a quantity,
however, forms an insoluble combination with the reduced indigo, and
thus makes a portion of the dye ineffective; at the same time it
combines with the extractive. In consequence of the fermentative action,
carbonic acid, acetic acid, and ammonia are disengaged; the first two of
which neutralize a portion of the lime, and require small quantities of
this earth to be added in succession; hence also a considerable quantity
of the carbonate of lime is found as a deposit on the sides and bottom
of the vat. In the sound condition of the indigo vat, no free lime
should be perceived, but on the contrary a free acid. Yet when the
disengaged carbonic and acetic acids saturate the lime completely, no
indigo can remain at solution; therefore a sufficient supply of lime
must always be left to dissolve the dye, otherwise the indigo would fall
down and mix with the extractive matter at the bottom. Goods dyed in the
blue vat are occasionally brightened by a boil in a logwood bath, with a
mordant of sulpho-muriate of tin, or in a bath of cudbear.

Another mode of mounting the indigo vat without woad and lime, is by
means of madder, bran, and potash. The water of the vat is to be heated
to the temperature of 122° F.; and for 120 cubic feet of it, 12 pounds
of indigo, 8 pounds of madder, and as much bran are to be added, with 24
pounds of good potashes; at the end of 36 hours, 12 pounds more of
potash are introduced, and a third 12 pounds in other 12 hours. In the
course of 72 hours, all the characters of the reduction and solution of
the indigo become apparent; at which time the fermentation must be
checked by the addition of quick-lime. The liquor has a bright full
colour, with a beautiful rich froth. In feeding the vat with indigo, an
equal weight of madder, and a double weight of potash should be added.
The odour of this vat in its mild but active state is necessarily
different from that of the woad vat, as no ammonia is exhaled in the
present case, and the sediment is much smaller. The reduced indigo is
held in solution by the carbonated potash, while the small addition of
quicklime merely serves to precipitate the indigo-brown.

A potash vat dyes in about half the time of the ordinary warm vat, and
penetrates fine cloth much better; while the goods thus dyed lose less
colour in alkaline and soap solutions. This vat may moreover be kept
with ease in good condition for several months; is more readily mounted;
and from the minute proportion of lime present, it cannot impair the
softness of the woollen fibres. It is merely a little more expensive. It
is said that cloth dyed in the potash indigo vat, requires one third
less soap in the washing at the fulling mill, and does not soil the
hands after being dressed. At Elbœuf and Louviers in France, such vats
are much employed. Wool, silk, cotton, and linen may all be dyed in
them.

_Cold vats._--The _copperas_ or _common blue vat_ of this country is so
named because the indigo is reduced by means of the protoxide of iron.
This salt should therefore be as free as possible from the red oxide,
and especially from any sulphate of copper, which would re-oxidize the
indigo. The necessary ingredients are: copperas (green sulphate of
iron), newly slaked quicklime, finely ground indigo, and water; to which
sometimes a little potash or soda is added, with a proportional
diminution of the lime. The operation is conducted in the following way:
the indigo well triturated with water or an alkaline lye, must be mixed
with hot water in the _preparation_ vat, then the requisite quantity of
lime is added, after which the solution of copperas must be poured in
with stirring. Of this _preparation_ vat, such a portion as may be
wanted is laded into the dyeing vat. For one pound of indigo three
pounds of copperas are taken, and four pounds of lime (or 1 of indigo,
2-1/2 of copperas, and 3 of lime). If the copperas be partially
peroxidized, somewhat more of it must be used.

A vat containing a considerable excess of lime is called a _sharp_ vat,
and is not well adapted for dyeing. A _soft_ vat, on the contrary, is
that which contains too much copperas. In this case the precipitate is
apt to rise, and to prevent uniformity of tint in the dyed goods. The
sediment of the copperas vat consists of sulphate of lime, oxide of
iron, lime with indigo brown, and lime with indigo blue, when too much
quicklime has been employed. The clear, dark wine yellow fluid contains
indigo blue in a reduced state, and indigo red, both combined with lime
and with the gluten of indigo dissolved. After using it for some time
the vat should be refreshed or fed with copperas and lime, upon which
occasion, the sediment must first be stirred up, and then allowed time
to settle again, and become clear. For obtaining a series of blue tints,
a series of vats of different strengths is required.

Linen and cotton yarn, before being dyed should be boiled with a weak
alkaline lye, then put upon frames or tied up in hanks, and after
removing the froth from the vat, plunged into, and moved gently through
it. For pale blues, an old, nearly exhausted vat, is used; but for deep
ones, a fresh nearly saturated vat. Cloth is stretched upon a proper
square dipping frame made of wood, or preferably of iron, furnished with
sharp hooks or points of attachment. These frames are suspended by cords
over a pulley, and thus immersed and lifted out alternately at proper
intervals. In the course of 8 or 10 minutes, the cloth is sufficiently
saturated with the solution of indigo, after which it is raised and
suspended so as to drain into the vat. The number of dippings determines
the depth of the shade; after the last the goods are allowed to dry,
taken off the frame, plunged into a sour bath of very dilute sulphuric
or muriatic acid, to remove the adhering lime, and then well rinsed in
running water. Instead of the dipping frames some dyers use a peculiar
roller apparatus, called _gallopers_, similar to what has been described
under CALICO PRINTING; particularly for pale blues. This cold vat is
applicable to cotton, linen and silk goods.

When white spots are to appear upon a blue ground, resist pastes are to
be used, as described under CALICO PRINTING.

The _urine vat_ is prepared by digestion of the ground indigo in warmed
stale urine, which first disoxygenates the indigo, and then dissolves it
by means of its ammonia. Madder and alum are likewise added, the latter
being of use to moderate the fermentation. This vat was employed more
commonly of old than at present, for the purpose of dyeing woollen and
linen goods.

The mode of making the china blue dye has been described under CALICO
PRINTING; as well as the _pencil blue_, or blue of application.

A blue dye may likewise be given by a solution of indigo in sulphuric
acid. This process was discovered by Barth, at Grossenhayn in Saxony,
about the year 1740, and is hence called the Saxon blue dye. The
chemical nature of this process has been already fully explained. If the
smoking sulphuric acid be employed, from 4 to 5 parts are sufficient for
1 of indigo; but if oil of vitriol, from 7 to 8 parts. The acid is to be
poured into an earthen-ware pan, which in summer must be placed in a tub
of cold water, to prevent it getting hot, and the indigo in fine powder,
is to be added with careful stirring, in small successive portions. If
it become heated, a part of the indigo is decomposed, with the
disengagement of sulphurous acid gas, and indigo green is produced.
Whenever all the indigo has been dissolved, the vessel must be covered
up, allowed to stand for 48 hours, and then diluted with twice its
weight of clear river water.

The undiluted mass has a black blue colour, is opaque, thick, attracts
water from the air, and is called _indigo composition_ or _chemic blue_.
It must be prepared beforehand, and kept in store. In this solution,
besides the _cerulin_, there are also indigo-red, indigo-brown, and
gluten, by which admixture the pure blue of the dye is rendered foul,
assuming a brown or a green cast. To remove these contaminations, wool
is had recourse to. This is plunged into the indigo previously diffused
through a considerable body of water, brought to a boiling heat in a
copper kettle, and then allowed to macerate as it cools for 24 hours.
The wool takes a dark blue dye by absorbing the indigo-blue sulphate and
hyposulphite, while at the same time the liquor becomes greenish blue;
and if the wool be left longer immersed, it becomes of a dirty yellow.
It must therefore be taken out, drained, washed in running water till
this runs off colourless, and without an acid taste. It must next be put
into a copper full of water, containing one or two per cent. of
carbonate of potash, soda, or ammonia (to about one third the weight of
the indigo), and subjected to a boiling heat for a quarter of an hour.
The blue salts forsake the wool, leaving it of a dirty red brown, and
dye the water blue. The wool is in fact dyed with the indigo red, which
is hardly soluble in alkali. The blue liquor may now be employed as a
fine dye, possessed of superior tone and lustre. It is called distilled
blue and _soluble blue_. Sulphuric acid throws down from it the small
quantity of indigo red, which had been held in solution by the alkali.

When wool is to be dyed with this sulphate of indigo blue, it must be
first boiled in alum, then treated with the blue liquor, and thus
several times alternately, in order to produce an uniform blue colour.
Too long continuance of boiling is injurious to the beauty of the dye.
In this operation the woollen fibres get impregnated with the
indigo-blue sulphate of alumina.

With sulphate of indigo, not only blues of every shade are dyed, but
also green, olive, gray, as also a fast ground to logwood blues; for the
latter purpose the preparatory boil is given with alum, tartar,
sulphates of copper and iron, and the blue solution; after which the
goods are dyed up with a logwood bath containing a little potash.

STATISTICAL TABLES of INDIGO; per favour of James Wilkinson, Esq., of
Leadenhall-Street.

EAST INDIA INDIGO.

  +------+---------+---------+---------+------------+---------------+
  |Years.| Produce |Consump- |Stock in |  Highest   | Good middling |
  |      |in India.| tion of |England  |   Price.   |    Violet.    |
  |      |         | World;  |  31st   |            |               |
  |      |         |average, |December.|            |               |
  |      |         |4 years. |         |            |               |
  +------+---------+---------+---------+------------+---------------+
  |      |         |         |         |    Per lb. |               |
  |      |_Chests._|_Chests._|_Chests._|    _s. d._ |_s. d.   s. d._|
  |1811  |  21,000 |  22,200 |  26,900 |     10  6  |  5  6    6  0 |
  |1812  |  23,500 |  22,500 |  29,500 |     11  6  |  6  9    7  3 |
  |1813  |  22,800 |  22,800 |  24,500 |     15  5  |  9  0    9  6 |
  |1814  |  28,500 |  23,000 |  24,900 |     13  0  |  7  9    8  3 |
  |1815  |  30,500 |  23,200 |  30,400 |     11  0  |  6  9    7  6 |
  |1816  |  25,000 |  26,900 |  25,700 |     10  0  |  5  0    5  6 |
  |1817  |  20,500 |  27,000 |  23,500 |     10  0  |  7  3    7  9 |
  |1818  |  19,100 |  26,500 |  24,000 |      9  3  |  6  9    7  3 |
  |1819  |  20,700 |  26,400 |  19,700 |      8  6  |  5  6    6  0 |
  |1820  |  27,200 |  24,200 |  14,500 |      9  0  |  6  3    6  9 |
  |1821  |  21,100 |  25,300 |   9,800 |     11  6  |  8  6    9  0 |
  |1822  |  25,700 |  26,000 |   8,200 |     12  0  |  9  0    9  6 |
  |1823  |  29,800 |  25,300 |  13,100 |     10  0  |  7  3    7  9 |
  |1824  |  24,100 |  26,500 |  12,200 |     15  0  | 12  0   12  6 |
  |1825  |  43,500 |  23,500 |  16,400 |     15  6  | 12  0   12  6 |
  |1826  |  28,000 |  27,300 |  22,300 |     11  3  |  7  6    7  9 |
  |1827  |  45,300 |  28,900 |  22,800 |     12  6  |  8  0    8  6 |
  |1828  |  30,000 |  31,000 |  31,100 |     10  0  |  6  3    6  6 |
  |1829  |  43,200 |  33,000 |  31,200 |      8  9  |  5  3    5  9 |
  |      |         |         |         |Years.      |               |
  |1830-1|  32,100 |  32,800 |  37,600 |1831  7  9  |  4  3    4  9 |
  |1831-2|  32,500 |  34,500 |  35,700 |1832  6  3  |  4  3    4  6 |
  |1832-3|  35,200 |  35,500 |  32,500 |1833  6  0  |  4  2    4  4 |
  |1833-4|  27,100 |  34,600 |  35,800 |1834  8  0  |  6  3    6  6 |
  |1834-5|  30,500 |  33,800 |  29,319 |1835  7  0  |  5  3    5  6 |
  |1835-6|  32,600 |  34,700 |  21,449 |1836  6  3  |  4  9    5  0 |
  |1836-7|    --   |  32,600 |  26,219 |1837  8  9  |  6  9    7  0 |
  +------+---------+---------+---------+------------+---------------+

EAST INDIA and SPANISH, &c. INDIGO.

  +------+------------------------+---------+------------+
  |      |      Importations.     |         |            |
  |Years.+-----------+------------+Exported.|    Home    |
  |      |East India.|Spanish, &c.|         |Consumption.|
  +------+-----------+------------+---------+------------+
  |      |   _lbs._  |   _lbs._   |  _lbs._ |   _lbs._   |
  | 1785 |   154,291 | 1,539,218  |  584,885|            |
  | 1786 |   253,345 | 1,724,945  |  466,696|            |
  | 1787 |   364,046 | 1,514,784  |  502,800|            |
  | 1788 |   622,691 | 1,473,920  |  445,857|            |
  | 1789 |   371,469 | 1,594,618  |  673,630|            |
  | 1790 |   531,619 | 1,307,088  |  821,131|            |
  | 1791 |   465,198 | 1,141,589  |  870,185|            |
  | 1792 |   581,827 | 1,274,538  |  880,951|            |
  | 1793 |   890,766 | 1,066,817  |  929,707|            |
  | 1794 | 1,403,650 | 1,487,642  |1,623,908|            |
  | 1795 | 2,862,684 | 1,424,941  |1,387,171|            |
  | 1796 | 3,897,120 |   680,915  |1,883,320|            |
  | 1797 | 1,754,233 |   535,845  |3,105,610|            |
  | 1798 | 3,862,188 |   192,060  |1,718,624|            |
  | 1799 | 2,529,377 |   512,459  |2,585,755|            |
  | 1800 | 2,674,317 | 1,076,417  |2,586,833|            |
  | 1801 | 2,123,637 |   827,696  |2,281,812|            |
  | 1802 | 2,264,199 |   669,679  |1,961,346|            |
  | 1803 | 2,632,110 |   522,825  |1,130,194|            |
  | 1804 | 2,765,871 |   395,258  |1,523,095|            |
  | 1805 | 4,666,292 |   687,319  |1,845,035|            |
  | 1806 | 2,612,181 |   319,394  |2,904,614|            |
  | 1807 | 5,326,032 |   715,809  |2,006,463|            |
  | 1808 | 5,314,860 |   477,625  |1,568,351|            |
  | 1809 | 2,179,083 |   674,048  |3,179,861|            |
  | 1810 | 5,243,613 |   883,061  |2,485,679|            |
  | 1811 | 4,453,932 |   658,577  |1,566,056|            |
  | 1812 | 4,461,793 |   354,171  |1,853,916|            |
  | 1813 | Accounts destroyed by Fire at Custom House.   |
  | 1814 | 6,803,064 |   328,881  |5,501,851|  3,406,282 |
  | 1815 | 5,543,852 |    79,253  |4,278,674|  2,774,091 |
  | 1816 | 7,247,227 |    39,275  |4,214,454|  1,899,819 |
  | 1817 | 5,001,280 |   134,313  |2,427,443|  2,377,659 |
  | 1818 | 5,497,768 |   187,257  |2,963,462|  2,302,163 |
  | 1819 | 3,689,052 |   129,682  |3,126,739|  2,033,601 |
  | 1820 | 4,924,222 |   161,164  |4,378,857|  2,288,196 |
  | 1821 | 3,943,592 |   119,517  |2,985,364|  1,959,509 |
  | 1822 | 2,549,284 |   374,230  |2,378,948|  2,004,062 |
  | 1823 | 6,557,296 |   664,408  |2,783,504|  2,322,221 |
  | 1824 | 4,595,707 |   485,110  |2,795,740|  2,493,350 |
  | 1825 | 6,233,335 |   560,296  |3,870,929|  2,381,233 |
  | 1826 | 7,699,439 |   386,312  |4,365,163|  1,901,047 |
  | 1827 | 5,404,811 |   662,936  |3,315,675|  2,399,365 |
  | 1828 | 9,683,626 |   229,384  |4,588,658|  3,064,915 |
  | 1829 | 5,978,527 |   769,757  |4,286,605|  2,113,830 |
  | 1830 | 7,920,924 |   295,516  |4,686,784|  2,676,945 |
  | 1831 | 7,004,510 |   290,089  |4,374,241|  2,490,134 |
  | 1832 | 6,221,725 |   131,340  |5,346,725|  2,395,653 |
  | 1833 | 6,304,016 |   331,016  |3,664,814|  2,323,300 |
  | 1834 | 3,798,144 |   357,152  |3,928,226|  2,447,827 |
  | 1835 | 3,986,233 |   183,480  |4,074,598|  2,606,772 |
  | 1836 | 6,753,898 |   418,800  |3,691,951|  2,864,274 |
  | 1837 | 5,872,601 |   673,270  |3,587,561|  2,240,451 |
  +------+-----------+------------+---------+------------+


INDIAN RUBBER, is the vulgar name of caoutchouc in this country.


INK; (_Encre_, Fr.; _Tinte_, Germ.) is a coloured liquid for writing on
paper, parchment, linen, &c. with a pen.

_Black ink._--Nut-galls, sulphate of iron, and gum, are the only
substances truly useful in the preparation of ordinary ink; the other
things often added merely modify the shade, and considerably diminish
the cost to the manufacturer upon the great scale. Many of these inks
contain little gallic acid, or tannin, and are therefore of inferior
quality. To make 12 gallons of ink we may take,--

  12 pounds of nutgalls,
   5 pounds of green sulphate of iron,
   5 pounds of gum senegal,
  12 gallons of water.

The bruised nutgalls are to be put into a cylindrical copper, of a depth
equal to its diameter, and boiled, during three hours, with three
fourths of the above quantity of water, taking care to add fresh water
to replace what is lost by evaporation. The decoction is to be emptied
into a tub, allowed to settle, and the clear liquor being drawn off, the
lees are to be drained. Some recommend the addition of a little
bullock’s blood or white of egg, to remove a part of the tannin. But
this abstraction tends to lessen the product, and will seldom be
practised by the manufacturer intent upon a large return for his
capital. The gum is to be dissolved in a small quantity of hot water,
and the mucilage, thus formed, being filtered, is added to the clear
decoction. The sulphate of iron must likewise be separately dissolved,
and well mixed with the above. The colour darkens by degrees, in
consequence of the peroxidizement of the iron, on exposing the ink to
the action of the air. But ink affords a more durable writing when used
in the pale state, because its particles are then finer, and penetrate
the paper more intimately. When ink consists chiefly of tannate of
peroxide of iron, however black, it is merely superficial, and is easily
erased or effaced. Therefore whenever the liquid made by the above
prescription has acquired a moderately deep tint, it should be drawn off
clear into bottles, and well corked up. Some ink-makers allow it to
mould a little in the casks before bottling, and suppose that it will
thereby be not so liable to become mouldy in the bottles. A few bruised
cloves, or other aromatic perfume, added to ink, is said to prevent the
formation of mouldiness, which is produced by the ova of infusoria
animalcules. I prefer digesting the galls, to boiling them.

The operation may be abridged, by peroxidizing the copperas beforehand,
by moderate calcination in an open vessel; but, for the reasons above
assigned, ink made with such a sulphate of iron, however agreeable to
the ignorant, when made to shine with gum and sugar, under the name of
japan ink, is neither the most durable nor the most pleasant to write
with.

From the comparatively high price of gall-nuts, sumach, logwood, and
even oak bark, are too frequently substituted, to a considerable
degree, in the manufacture of ink.

The ink made by the prescription given above, is much more rich and
powerful than many of the inks commonly sold. To bring it to their
standard, a half more water may safely be added, or even 20 gallons of
tolerable ink may be made from that weight of materials, as I have
ascertained.

Sumach and logwood admit of only about one half of the copperas that
galls will take to bring out the maximum amount of black dye.

Chaptal gives a prescription in his _Chimie appliquée aux arts_, which,
like many other things in that book, are published with very little
knowledge and discrimination. He uses logwood and sulphate of copper, in
addition to the galls and sulphate of iron; a pernicious combination
productive of a spurious fugitive black, and a liquor corrosive of pens.
It is, in fact, a modification of the vile dye of the hatters.

Lewis, who made exact experiments on inks, assigned the proportion of 3
parts of galls to 1 of sulphate of iron, which, with average galls, will
answer very well; but good galls will admit of more copperas.

_Gold ink_ is made by grinding upon a porphyry slab, with a muller, gold
leaves along with white honey, till they be reduced to the finest
possible division. The paste is then collected upon the edge of a knife
or spatula, put into a large glass, and diffused through water. The gold
by gravity soon falls to the bottom, while the honey dissolves in the
water, which must be decanted off. The sediment is to be repeatedly
washed till entirely freed from the honey. The powder, when dried, is
very brilliant, and when to be used as an ink, may be mixed up with a
little gum water. After the writing becomes dry, it should be burnished
with a wolf’s tooth.

_Silver ink_ is prepared in the same manner.

_Indelible ink._--A very good ink, capable of resisting chlorine, oxalic
acid, and ablution with a hair pencil or sponge, may be made by mixing
some of the ink made by the preceding prescription, with a little
genuine China ink. It writes well. Many other formulæ have been given
for indelible inks, but they are all inferior in simplicity and
usefulness to the one now prescribed. Solution of nitrate of silver
thickened with gum, and written with upon linen or cotton cloth,
previously imbued with a solution of soda, and dried, is the ordinary
permanent ink of the shops. Before the cloths are washed, the writing
should be exposed to the sun-beam, or to bright daylight, which blackens
and fixes the oxide of silver. It is easily discharged by chlorine and
ammonia.

_Red ink._--This ink may be made by infusing, for 3 or 4 days in weak
vinegar, Brazil wood chipped into small pieces; the infusion may be then
boiled upon the wood for an hour, strained, and thickened slightly with
gum arabic and sugar. A little alum improves the colour. A decoction of
cochineal with a little water of ammonia, forms a more beautiful red
ink, but it is fugitive. An extemporaneous red ink of the same kind may
be made by dissolving carmine in weak water of ammonia, and adding a
little mucilage.

_Green ink._--According to Klaproth, a fine ink of this colour may be
prepared by boiling a mixture of two parts of verdigris in eight parts
of water, with one of cream of tartar, till the total bulk be reduced
one half. The solution must be then passed through a cloth, cooled, and
bottled for use.

_Yellow ink_ is made by dissolving 3 parts of alum in 100 of water,
adding 25 parts of Persian or Avignon berries bruised, boiling the
mixture for an hour, straining the liquor, and dissolving in it 4 parts
of gum arabic. A solution of gamboge in water forms a convenient yellow
ink.

By examining the different dye-stuffs, and considering the processes
used in dyeing with them, a variety of coloured inks may be made.

_China ink._--Proust says, that lamp-black purified by potash lye, when
mixed with a solution of glue, and dried, formed an ink which was
preferred by artists to that of China. M. Merimée, in his interesting
treatise, entitled, _De la peinture à l’huile_, says, that the Chinese
do not use glue in the fabrication of their ink, but that they add
vegetable juices, which render it more brilliant and more indelible upon
paper. When the best lamp-black is levigated with the purest gelatine or
solution of glue, it forms, no doubt, an ink of a good colour, but wants
the shining fracture, and is not so permanent on paper as good China
ink; and it stiffens in cold weather into a tremulous jelly. Glue may be
deprived of the gelatinizing property by boiling it for a long time, or
subjecting it to a high heat in a Papin’s digester; but as ammonia is
apt to be generated in this way, M. Merimée recommends starch gum made
by sulphuric acid (British gum) to be used in preference to glue. He
gives, however, the following directions for preparing this ink with
glue. Into a solution of glue he pours a concentrated solution of
gall-nuts, which occasions an elastic resinous-looking precipitate. He
washes this matter with hot water, and dissolves it in a spare solution
of clarified glue. He filters anew, and concentrates it to the proper
degree for being incorporated with the purified lamp-black. The
astringent principle in vegetables does not precipitate gelatine when
its acid is saturated, as is done by boiling the nutgalls with limewater
or magnesia. The first mode of making the ink is to be preferred. The
lamp-black is said to be made in China, by collecting the smoke of the
oil of sesame. A little camphor (about 2 per cent.) has been detected in
the ink of China, and is supposed to improve it. infusion of galls
renders the ink permanent on paper.

_Sympathetic ink._ The best is a solution of muriate of cobalt.

_Printer’s ink._ See this article.

By decomposing vanadate of ammonia with infusion of galls, a liquid is
obtained of a perfectly black hue, which flows freely from the pen, is
rendered blue by acids, is insoluble in dilute alkalis, and resists the
action of chlorine. Whenever the metal vanadium shall become more
abundant, as it probably may ere long, we shall possess the means of
making an ink, at a moderate price, much superior to the tannate and
gallate of iron.

To prepare the above vanadic salt cheaply, the cinder or hammerschlag
obtained from the iron made at Ekersholm, in Sweden, or other iron which
contains vanadium, being reduced to a fine powder, is to be mixed with
two thirds of its weight of nitre, and one third of effloresced soda.
The mixture is to be ignited in a crucible; cooled and lixiviated,
whereby solutions of the vanadates of potash and soda are obtained, not
pure, indeed, but sufficiently so for being decomposed, by means of sal
ammoniac, into a vanadate of ammonia. This being rendered nearly neutral
with any acid, constitutes an excellent indelible ink.


INULINE; (Eng. and Fr.) is a substance first extracted from the root of
the _Inula-Hellenium_, or Elecampane. It is white and pulverulent like
starch; and differs from this substance chiefly because its solution,
when it cools, lets fall the inuline unchanged in powder, whereas starch
remains dissolved in the cold, as a jelly or paste.

Inuline is obtained by boiling the root sliced in 3 or 4 times its
weight of water, and setting the strained decoction aside till it cools,
when the pulverulent inuline precipitates. It exists also in the roots
of colchicum, and pellitory.


IODINE; (_Iode_, Fr.; _Iod_, Germ.) is one of the archæal undecompounded
chemical bodies, which was discovered accidentally in 1812 by M.
Courtois, a manufacturer of saltpetre, in the mother-waters of that
salt. Its affinities for other substances are so powerful as to prevent
it from existing in an insulated state. It occurs combined with
potassium and sodium in many mineral waters, such as the brine spring of
Ashby-de-la-Zouche, and other strongly saline springs. This combination
exists sparingly in sea-water, abundantly in many species of _fucus_ or
sea-weed, and in the kelp made from them; in sponges; in several marine
_molluscæ_, such as the _doris_, the _venus_, oysters, &c.; in several
polyparies, and sea plants, as the _gorgonia_, the _zostera marina_,
&c.; particularly in the mother-waters of the salt works upon the
Mediterranean sea; and it has been found in combination with silver, in
some ores brought from the neighbourhood of Mexico.

Iodine is most economically procured from the mother-water of kelp, as
furnished by those manufacturers of soap in Scotland and elsewhere who
employ this crude alkaline matter. By pouring an excess of sulphuric
acid upon that liquid, and exposing the mixture to heat in a retort,
iodine rises in _violet_ vapours (whence its name), and condenses in the
receiver into black, brilliant, soft, scaly crystals, resembling
graphite or plumbago. An addition of the peroxide of manganese to the
above mixture, favours the production of iodine. Soubeiran has proposed,
as a means of extracting it in greater abundance from a given quantity
of the said mother-waters, to transform the iodide of potash or soda,
present, into an insoluble iodide of copper, by pouring into them
solution of sulphate of copper, which precipitates first of all one half
of the iodine. He then decants the supernatant liquor, and adds to it a
fresh quantity of the sulphate along with some iron filings. The latter
metal seizes the oxygen and sulphuric acid of the cupreous salt, sets
the copper free, which then seizes the other half of the iodine. To
separate this iodide from the remaining iron filings, he agitates the
whole with water, and decants the liquor. The filings immediately
subside, but the iodide of copper remains for some time in a state of
suspension. This compound, separated by a filter cloth, is to be mixed
with twice its weight of the black peroxide of manganese, and as much
sulphuric acid as will make the mixture into a paste; which mixture
being introduced into a retort, and distilled, the iodine comes over in
its characteristic violet vapours, which are condensed into the
glistening black substance in the receiver.

Iodine is always solid at atmospheric temperatures, though it slowly
flies off with a peculiar offensive penetrating odour somewhat like
chlorine. Its specific gravity is 4·946 at the temperature of 58° Fahr.
Its prime equivalent, according to Berzelius, is 63·283, one volume of
hydrogen being 1·000; but 126·566, if two volumes of hydrogen be
reckoned unity, as most British chemists estimate it, from the
composition of water. It possesses in a high degree electro-negative
properties, like oxygen and chlorine; and therefore makes its appearance
at the positive pole, when its compounds are placed in the voltaic
circuit. It stains the skin yellow; and if applied for some time to it,
is apt to produce painful ulcerations.

Iodine melts only at about 390° Fahr.; but with the vapour of water it
volatilizes at 212°. It has a great affinity for hydrogen, and
constitutes by that union hydriodic acid; a compound resembling in some
respects muriatic or hydrochloric acid. It also can be combined with
oxygen, and forms thereby iodic acid. Its compounds with carbon,
phosphorus, sulphur, chlorine, azote, and many metals have not been
applied to any manufacturing purpose, and therefore need not be
described here.

The chief application of iodine in the arts, is for the detection of
starch, which its watery solution, though containing only one part in
5000, does readily, by the production of a deep purple colour; this
vanishes by exposing the starch to the air for some time, or more
quickly by heating it.

As a medicine, iodine and its compounds, such as the iodides of
potassium and iron, are supposed to possess great powers in resolving
glandular swellings. The periodide of mercury is a brilliant red
pigment, but somewhat evanescent.

Chlorine, bromine, and iodine are frequently associated; and it has
hitherto been reckoned a difficult problem to separate them from one
another. The following plan is proposed by M. Lövig.

Heat the mixture of the dried chloride and bromide (or chloride and
iodide) while a current of chlorine is made to pass over it, till no
more bromine is carried off by the chlorine. Receive the gases in a
solution of potash; saturate this fluid mixture of the chloride of
potassium, and the chlorate and bromate of potash with nitric acid,
adding afterwards nitrate of silver. A mixture of bromate and chloride
of silver will precipitate. Dry the precipitate, calcine it, and
calculate the proportion of bromine from the volume of oxygen gas now
disengaged. It would be preferable to digest in a phial, the precipitate
while moist, along with water of baryta, which decomposes the bromate of
silver without acting upon the chloride. The excess of baryta being
thrown down by carbonic acid, and the liquid being evaporated, a bromate
of baryta is obtained, which may be washed with alcohol of 0·840. The
solution of bromate of baryta may also be neutralized by nitric acid,
and the bromic acid may be precipitated by nitrate of silver. The same
method is applicable to the separation of iodine from chlorine.

After throwing down the solution of the mixed salts by nitrate of
silver, Berzelius digests the washed precipitate in a closed bottle of
water of baryta; whence results bromate of baryta without any chloride
of barium. On evaporating the liquor we obtain crystallized bromate of
baryta, which may be freed from a small accidental quantity of chloride,
by washing with alcohol at 0·840. By calcination we then obtain bromide
of barium, which being distilled with sulphuric acid and peroxide of
manganese, affords bromine.


IRIDIUM, is a metal discovered by Descotils in 1803, as also by Tennant
in 1804; and is so called because its different solutions exhibit all
the colours of the rainbow. It occurs only in the ore of platinum, being
found there in two states; 1. united to that metal, and 2., as alloy of
osmium and iridium, in the form of small, insulated, hard grains.
Iridium is the most refractory of all the metals; and appears as a gray
metallic powder. It is not fused by the flame of the hydroxygen lamp.


IRON; (_Fer_, Fr.; _Eisen_, Germ.) is a metal of a bluish-gray colour,
and a dull fibrous fracture, but it is capable of acquiring a brilliant
surface by polishing. Its specific gravity is 7·78. It is the most
tenacious of metals, and the hardest of all those which are malleable
and ductile. It is singularly susceptible of the magnetic virtue, but in
its pure state soon loses it. When rubbed it has a slight smell, and it
imparts to the tongue a peculiar astringent taste, called chalybeate. In
a moist atmosphere, iron speedily oxidizes, and becomes covered with a
brown coating, called rust.

Every person knows the manifold uses of this truly precious metal; it is
capable of being cast in moulds of any form; of being drawn out into
wires of any desired strength or fineness; of being extended into plates
or sheets; of being bent in every direction; of being sharpened,
hardened, and softened at pleasure. Iron accommodates itself to all our
wants, our desires, and even our caprices; it is equally serviceable to
the arts, the sciences, to agriculture, and war; the same ore furnishes
the sword, the ploughshare, the scythe, the pruning hook, the needle,
the graver, the spring of a watch or of a carriage, the chisel, the
chain, the anchor, the compass, the cannon, and the bomb. It is a
medicine of much virtue, and the only metal friendly to the human frame.

The ores of iron are scattered over the crust of the globe with a
beneficent profusion, proportioned to the utility of the metal; they are
found under every latitude, and every zone; in every mineral formation,
and are disseminated in every soil. Considered in a purely mineralogical
point of view, without reference to their importance for reduction, they
may be reckoned to be 19 in number; namely, 1. native iron of three
kinds: pure, nickeliferous, and steely; 2. arsenical iron; 3. yellow
sulphuret of iron; 4. white sulphuret of iron; 5. magnetic sulphuret of
iron; 6. black oxide of iron, either the loadstone, or susceptible of
magnetism, and titaniferous; 7. compact _fer oligiste_, specular iron
ore, as of Elba, and scaly _fer oligiste_; 8. hematite, affording a red
powder; 9. hematite or hydrate of iron, affording a yellow powder, of
which there are several varieties; 10. pitchy iron ore; 11.
siliceo-calcareous iron, or yenite; 12. sparry carbonate of iron, and
the compact clay iron-stone of the coal formation; 13. phosphate of
iron; 14. sulphate of iron, native copperas; 15. chromate of iron; 16.
arseniate of iron; 17. muriate of iron; 18. oxalate of iron; 19.
titanate of iron.

Among all these different species, ten are worked by the miner, either
for the sake of the iron which they contain; for use in their native
state; or for extracting some principles from them advantageous to the
arts and manufactures; such are arsenical iron, sulphate of iron,
sulphuret of iron, and chromate of iron.

1. _Native iron_ A. Pure.--This species is very rare, and its existence
was long matter of dispute; though it has been undoubtedly found not
only in volcanic formations, but in veins properly so called. It is not
entirely like our malleable iron; but is whiter, more ductile, more
permanent or less oxidizable in the air, and somewhat less dense. Among
the best attested examples of pure native iron is that observed by M.
Schreber, in the mountain of Oulle near Grenoble. The metal was
entangled in a vein running through gneiss, and appeared in ramifying
stalactites, enveloped in fibrous brown-oxide of iron mixed with quartz
and clay.

B. The _native nickeliferous_ or _meteoric iron_ is very malleable,
often cellular, but sometimes compact, and in parallel plates, which
pass into rhomboids or octahedrons. It is naturally magnetic, and by its
nickel is distinguishable from terrestrial native iron. Macquart, in
describing the famous mass found at mount Kemir in Siberia, says that
the iron is perfectly flexible, and fit for making small instruments at
a moderate heat; but in too strong a fire, the metal becomes short,
brittle, and falls into grains under the hammer. Meteoric iron is
covered with a sort of varnish which preserves its surface from the
rusting action of the air; but this preservative property does not
extend to the interior. Chladni has given a list of masses of meteoric
iron, which have been known to fall at different times from the
atmosphere, and of many specimens which indicate their atmospheric
origin, by their aspect and composition. A portion of the mass of
meteoric iron found at Santa-Rosa near Santa-Fe-de-Bogota, was made into
a sword, and presented to Bolivar.

C. _Native steel-iron._--This substance has all the characters of
cast-steel; it occurs in a kind of small button ingots, with a finely
striated surface, and a fracture exceedingly fine grained. It is hardly
to be touched by the file, and will scarcely flatten under the hammer.
M. Mossier found this native steel at the village of Bouiche, near Nery,
department of the Allier, in a spot where there had existed a seam of
burning coal. A mass of 16 pounds and 6 ounces of native steel was
discovered in that place, besides a great many small globules.

2. _Arsenical iron_, _Arsenikkies_ or _Mispickel_, is a tin-white
mineral, which emits a garlic smell at the blowpipe, or even when sparks
are struck from it by steel, accompanied with a small train of white
smoke. It contains generally more or less sulphur and sometimes a little
silver, associated with metallic arsenic and iron.

3. _Yellow sulphuret of iron_, commonly called _Marcasite_, or Martial
pyrites. The bronze or brass-yellow colour enables us to recognize this
mineral. At the blowpipe it gives off its sulphur, and is converted into
a globule attractable by the blowpipe. It is a bisulphuret of iron
containing 32 of sulphur and 28 of metal.

Copper pyrites may be distinguished from it by its golden yellow colour,
which is frequently iridescent, and by its inferior hardness; for it
does not strike fire with steel, like the preceding persulphuret. There
is no vein, stratum, or mass of metallic ore which does not contain some
iron pyrites; and it is often the sole mineral that fills the veins in
quartz. It sometimes contains gold, and at other times silver.

4. _White sulphuret of iron._--This is distinguishable from the
preceding species only by its colour and form of crystallization, and
was hence till lately confounded with it by mineralogists. Its surface
is often radiated.

5. _Magnetic sulphuret of iron_, the _Magnetkies_ of the Germans.--This
ore is attractable by the magnet like common iron. Its colour is
reddish-yellow, passing into brown; its fracture is rough. It consists
of 16 of sulphur and 28 of iron.

6. _Black oxide of iron_, _magnet ore_, or _native loadstone_.--One
variety of this species has two poles in each specimen, which manifest a
repulsive action against the corresponding poles of a magnetic needle.
All the varieties furnish a black powder. Its external colour is a gray
approaching to that of metallic iron, but somewhat duller; with
occasional iridescence of surface. Neither nitric acid nor the blowpipe
has any action upon it. Its specific gravity varies from 4·24 to 5·4;
and its constituents are 71·86 peroxide, and 28·14 protoxide, according
to Berzelius; or in 100 parts, 71·74 of metallic iron, and 28·26 of
oxygen. Assuming the prime equivalent of iron to be 28, with the British
chemists, then an ore consisting, like the above, of two prime
proportions of peroxide, and one of protoxide, would be represented by
the number 116 = 80 + 36; and would consist in 100 parts, of iron 72·4,
oxygen 27·6.

Magnetic iron-ore belongs to primitive rock formations, and occurs
abundantly in Sweden, Dalecarlia, Norway, Siberia, China, Siam, and the
Philippine Isles; but it is rare in England and France. It is worked
extensively in Sweden, and furnishes an excellent iron.

The titaniferous oxide of iron, or iron sand, is also attractable by the
magnet. Its colour is a deep black, with some metallic lustre; it is
perfectly opaque: its fracture is conchoidal; it is hard and difficult
to grind under the pestle into a dull black powder, which stains the
fingers when it is very fine; it melts at a high heat into a black
enamel without lustre. All volcanic rocks contain a greater or less
quantity of titanic iron-ore, disseminated through them, which may be
recognised by its brilliant metallic lustre, and its perfect conchoidal
fracture.

7. _Fer oligiste, iron-glance, specular iron and red iron-ore._--This
ore has the colour of polished steel; and the light transmitted through
the thin edges of its crystals appears of a beautiful red. Its powder is
always of a well marked brown-red hue, passing into cherry-red, which
distinguishes it from the black-oxide ore. Its fracture is rough, or
vitreous in certain varieties; it breaks easily; but it is hard enough
to scratch glass. It usually contains from 60 to 70 of metallic iron in
100 parts; the equivalent proportion of oxygen in the pure red oxide of
iron being 30 parts combined with 70 of metal. It is a mistake to
suppose any specular iron ore capable of yielding 85 per cent. of iron,
for 100 parts of even protoxide of iron contain only 77·77 parts of
metal.

The compact variety comprises the crystals of the island of Elba, and of
Framont in the Vosges, which have a rough-grained fracture. It exists in
very great masses, constituting even entire mountains; in the cavities
and fissures of these masses, the beautiful crystals so much prized by
collectors of minerals, occur.

[Illustration: 581]

The island of Elba is equally celebrated for its inexhaustible abundance
of rich specular iron-ore, and for the immemorial antiquity of its
mining operations. _Fig._ 581. is a vertical section passing through the
three workings, called Pietamonte (D), Sanguinaccio (E), Antenna (F),
through an antient excavation _a_, through the coast _o_, and the mole
_p_, ending at the canal of Piombino. The total height of the
metalliferous mountain above the level of the sea, is no more than 180
metres, or 600 feet.

The rock which constitutes the body of this little mountain _d l_, is
called _bianchetta_ by the workmen. It is a white slaty talc, slightly
ochreous, or yellowish, consisting chiefly of silica and alumina, with
some magnesia.

The ore of Antenna (F) is a very hard compact _fer oligiste_, of a
brilliant metallic aspect. The workable bed has a height of 66 feet, and
consists of metalliferous blocks mixed confusedly with sterile masses of
the rock; the whole covered with a rocky detritus, under a brownish
mould. From its metallic appearance and toughness, this bed is called
_vena ferrata_, the iron vein. In Pietamonte the workable bed is
composed entirely of micaceous specular iron ore (_fer oligiste_), with
its fissures filled with yellow ochre. This bed rests upon the rock
called _bianchetta_; the brilliant aspect of ore in this place has
gained for it the name of _vena lucciola_.

The metalliferous hill _d l_, extends to the north-east, about a mile
beyond the workings D E F. The ore contains about 65 per cent. of iron,
and is smelted in Catalan forges.

The following description of the figure will make the structure of this
extraordinary mine well understood. _a_, is a great excavation, the
result of antient workings.

1, 1; 2, 2; 3, 3, 4, 4, 5, 6, and 7, are roads for carrying off the
rubbish, in correspondence with the several working levels.

_b_, _b_, _b_, masses of old rubbish (_deblais_).

_c_, _c_, ditto, from the present workings D, E, F.

_d_, the rocky mass called bianchetta, against which the ore extracted
from _a_, abuts.

_e_, the surface of a bed of ore, near the streamlet _g_.

_f_, _f_, indication of beds of iron pyrites and _fer oligiste_.

_g_, a small rivulet preceding from the infiltration of rains, and which
is impregnated with acidulous sulphate of iron.

_h_, _h_, ravine which separates the metalliferous hill _d l_, from the
barren hill _i_.

_k_, masses of slags from ancient smelting operations; such are very
common in this island. None of any consequence now exists; nearly the
whole of the ore being exported to Tuscany, the Romagna, the Genoese
territories, Piedmont, Naples, and Corsica.

_l_, a considerable body of rubbish from ancient workings, towards the
summit of the metalliferous hill _d_, _l_.

_m_, _m_, part of this hill covered with rubbish, the result of old
workings.

_n_, the site called _Vigneria_.

_o_, houses upon the shore called _Marine de Rio_, where the workpeople
live, and the mineral is kept in store.

_p_, wooden pier (_mole_) whence the ore is shipped; terminated by a
small tower _q_.

Compact _fer oligiste_ occurs also in the Vosges, in Corsica, at
Altenberg and Freyburg in Saxony, Presnitz in Bohemia, Norberg and
Bisberg in Sweden, &c.

The varieties called specular _fer oligiste_, and scaly _fer oligiste_,
or iron-glance, do not differ essentially from the compact. None of them
affects the magnetic needle, and their powder is a red of greater or
less vivacity.

8. _Red oxide of iron._--The varieties included under this species
afford a red powder, do not affect the magnetic needle, and are
destitute of metallic lustre. At the blowpipe they all become black, or
deep brown; and then they act on the needle. The crystallized variety
consists of 70 iron and 30 oxygen in 100 parts. The concretionary kind,
or _hematite_, has a brown-red colour; is solid, compact, and sometimes
very hard; its surface may be filed and polished so as to acquire a
lustre almost metallic; its internal structure is fibrous, and it
exhibits sometimes a resemblance to splinters of wood. Its outer surface
is constantly concretionary, mammelated, and presents occasionally
sections of a sphere, or cylinders attached to each other. This is the
blood-stone of the burnisher of metals. It is a very common mineral. The
ochry variety or red-iron-ochre is distinguished from the solid hematite
by the brightness of its colour. It is used as a pigment.

9. _Brown oxide of iron, brown iron-stone._--This affords always a
yellow powder, without any shade of red, which passes sometimes into the
bistre brown, or velvet black. At the blowpipe this oxide becomes brown,
and very attractable by the magnet; but after calcination and cooling,
the ore yields a red powder, which stains paper nearly as red as
hematite does; and which is much employed in polishing metals. All the
yellow or brown oxides contain a large proportion of water, in chemical
combination; and hence this species has been called hydrate of iron.
There are several varieties which assume globular, reniform,
stalactitic, and fruticose shapes. As impure varieties of the species we
must consider some of the clay-iron-ores, such as the granular, the
common, the pisiform, and the reniform clay-iron-ore. According to
D’Aubuisson, the present species consists of peroxide of iron, from 82
to 84 _per cent._; water, 14 to 11; oxide of manganese, 2; silica, 1 to
2. It is therefore a hydrated peroxide of iron; and ought by theory, to
consist, in its absolute state, of 81·63 peroxide, and 18·37 water. It
occurs both in beds and veins. The _œtites_ or eagle-stones form a
particular variety of this ore. On breaking the balls so named, they are
observed to be composed of concentric coats, the outside ones being very
hard, but the interior becoming progressively softer towards the centre,
which is usually earthy and of a bright yellow colour; sometimes however
the centre is quite empty, or contains only a few drops of water. Œtites
occur in abundance, often even in continuous beds in secondary
mountains, and in certain argillaceous strata. These stones are still
considered by the French shepherds as amulets or talismans, and may be
found in the small bags which they suspend to the necks of their
favourite rams; and they are in such general use that a large quantity
is annually imported into France from the frontiers of Germany, for this
superstitious purpose. When smelted, they yield a good iron.

The variety called _granular brown oxide_, _or bone ore_, is merely a
modification of the preceding. It occurs in grains nearly round, varying
in size from a millet seed to a pea, each being composed of concentric
coats, hard outside and soft within. They are generally agglutinated by
a calcareous or argillaceous paste; but are occasionally quite loose.
This ore occurs in calcareous formations, and is sometimes accompanied
with shells, such as _terebratulæ_. The brittle quality of the iron
afforded by it, has been ascribed to the phosphorus derived from the
large quantity of organic bodies, with which the ore is frequently
mixed. The bog-iron-ore, and swamp iron ore belong to this species.

10. _Pitchy hydrate of iron._--This is a rare mineral of a resinous
aspect, found in a vein in the mine of Braunsdorf, two leagues from
Freyberg, and seems to consist of red oxide of iron and water.

11. _Yenite_, is a mineral species rather rare, composed of red oxide of
iron, silica, and lime.

12. _Carbonate of iron, sparry iron, or brown-spar._--This important
species has been divided into two varieties; spathose iron, and the
compact carbonate. The first has a sparry and lamellar fracture; with a
colour varying from yellowish-gray to isabella yellow, or even to
brownish-red. It turns brown without melting at the blowpipe, and
becomes attractable by the magnet after being slightly roasted in the
flame of a candle. Even by a short exposure to the air, after its
extraction from the mine, it also assumes the same brown tint, but
without acquiring the magnetic quality. It affords but a slight
effervescence with nitric acid, changing merely to a red-brown colour.
Its specific gravity varies from 3·00 to 3·67. Its primitive form is
like that of carbonate of lime, an obtuse rhomboid. Without changing
this form, its crystals are susceptible of containing variable
quantities of carbonate of lime, till it passes wholly into this
mineral. Manganese and magnesia enter also occasionally into its
composition.

Sparry carbonate of iron belongs to primitive formations; forming
powerful veins in mountains of gneiss, and is associated in these veins
with quartz, copper pyrites, gray copper, fibrous brown oxide of iron,
and a variety of ramose carbonate of lime, vulgarly called _flos ferri_.
Thus it is found at Allevard and Vizille, near Grenoble, at Saint-George
d’Huretière, in the Alps of Savoy; at Baigorry, in the Lower Pyrenees;
at Eisenerz, in Styria; at Hüttenberg, in Carinthia; at Schwartz, in the
Tyrol; in Saxony, Hungary, other places in Germany, as also in Spain,
Sweden, Norway, and Siberia. It also occurs along with galena, and other
ores of lead, in the mines of Lead-Hills, and Wanlockhead, in Scotland;
and in the mines of Cumberland, Northumberland, and Derbyshire; likewise
with tin-ore, at Wheal Maudlin, Saint-Just, and other places in
Cornwall.

This ore viewed as a metallurgic object, is one of the most interesting
and valuable that is known; it affords natural steel with the greatest
facility, and accommodates itself best to the Catalan smelting forge. It
was owing in a great measure to the peculiar quality of the iron which
it produces, that the excellence long remarked in the cutlery of the
Tyrol, Styria, and Carinthia was due. It was called by the older
mineralogists _steel ore_.

The carbonate of iron of the coal formation, is the principal ore from
which iron is smelted in England and Scotland, and it yields usually
from 30 to 33 per cent. of cast metal. We are indebted to Dr. Colquhoun
for several elaborate analyses of the sparry-irons of the Glasgow coal
field; ores which afford the best qualities of iron made in that
district. The richest specimen out of the nine which he tried, came from
the neighbourhood of Airdrie; it had a specific gravity of 3·0533, and
afforded in 100 parts; carbonic acid, 35·17; protoxide of iron, 53·03;
lime, 3·33; magnesia, 1·77; silica, 1·4; alumina, 0·63; peroxide of
iron, 0·23; carbonaceous or bituminous matter, 3·03; moisture and loss,
1·41. Its contents in metallic iron are 41·25.

The _compact carbonate of iron_ has no relation externally with the
sparry variety. It comprehends most of the clay-iron-stones, and
particularly that which occurs in flattened spheroidal masses of various
size, among the coal measures. The colour of this ore is often a
yellowish-brown, reddish-gray, or a dirty brick-red. Its fracture is
close grained; it is easily scratched, and gives a yellowish-brown
powder. It adheres to the tongue, has an odour slightly argillaceous
when breathed upon, makes no effervescence with any acid, blackens at
the blowpipe without melting, and becomes attractable by the magnet with
the slightest calcination.

This ore affords from 30 to 40 per cent. of iron of excellent quality;
and it is the object of most extensive workings in Great Britain. It
occurs in the slaty clay which serves as a roof or floor to the strata
of coal; and also in continuous beds, from 2 to 18 inches thick, among
the coal measures, as in Staffordshire, Shropshire, and Wales. It is
remarkable, that the coal-basin of Newcastle contains little clay
iron-stone, while the coal-basin of Dudley is replete with it.

13. _Phosphate of iron._--A dull blue colour is the most remarkable
external character of this species, which occurs in small masses
composed of aggregated plates, sometimes in an excessively fine powder,
or giving other bodies a blue tinge. It assumes at the blowpipe a rusty
hue, and is then reduced to a button of a metallic aspect. It dissolves
completely in dilute nitric acid, as well as in ammonia, but it does not
communicate its colour to them, and oil turns it black; characters which
distinguish it readily from blue carbonate of copper, whose colour is
not altered by ammonia. It is of no use as a smelting ore.

14. _Sulphate of iron, native green vitriol._--This is formed by the
oxygenation of sulphuret of iron, and is unimportant in a metallurgic
point of view.

15. _Chromate of iron._--For the treatment and use of this ore, see
CHROME.

16. _Arseniate of iron, Wurfelerz._

17. _Muriate of iron._

18. _Oxalate of iron_; _Humboldtite_, found by M. Breithaupt in the
lignite of Kolaw. It consists of protoxide of iron, 53·86; oxalic acid,
46·14; in 100.

19. _Titanate of iron_, consists of protoxide and peroxide of iron, 86;
titanic acid, 8; oxide of manganese, 2; gangue, 1 = 97. See _Black
Oxide_ of iron.

_Of the assay of iron-ores by fusion._--In the assays by the dry way,
the object is to separate exactly all the iron which the ore may
contain, with the view of comparing the result with the product of
smelting on the great scale. In order to succeed in this operation, we
must deoxidize the iron, and produce at the same time such a temperature
as will melt the metal and the earths associated with it in the ore, and
obtain the former in a dense button at the bottom of a crucible, and the
latter in a lighter glass or slag, above it. Sometimes the gangue of the
ores, consisting mostly of a single earth, as quartz, alumina, or lime,
is of itself very refractory, and hence some flux must be added to bring
about the fusion. The substance most commonly employed for this purpose
is borax; but ordinary flint glass may be substituted for it. Sometimes,
also, instead of adding borax, which always succeeds, lime or clay may
be added to the ore, according to the nature of its mineralizer; that
is, lime for a clay iron-stone, and clay for a calcareous carbonate of
iron; and both, when the gangue is siliceous, as occurs with the black
oxide.

The ore, pulverized and passed through a silk sieve, is to be well mixed
with the flux, and the mixture introduced into the smooth concavity made
in the centre of a crucible lined with hard rammed damp charcoal dust.
Were the mixture diffused through the charcoal, the reduced iron would
be apt to remain scattered in little globules through the crucible, and
no metallic button would be formed at its bottom. The mingled ore and
flux must be covered with charcoal. The crucible thus filled must be
shut with an earthen lid luted on with fire-clay; and it is then set on
its base, either in an air furnace, or on the hearth of a forge urged
with a smith’s bellows. The heat should be very slowly raised, not
employing the bellows till three quarters of an hour have expired. In
this way, the water of the damp charcoal (_brasque_) is allowed to
exhale slowly, and the deoxidation is completed before the fusion
begins; for by acting otherwise, the slags formed would dissolve some
oxide of iron, and the assay would not indicate the whole of the iron to
be obtained from the ore. At the end of the above period, the fire must
be raised progressively to a white heat, at which pitch it must be
maintained for a quarter of an hour, after which the crucible should be
withdrawn. Whenever it has cooled, it is to be opened, the _brasque_
must be carefully removed or put aside, and the button of cast-iron
taken out and weighed. The _brasque_ may sometimes contain a few
globules, which must be collected by washing in water, or the
application of a magnetic bar. The quantity of iron denotes, of course,
the richness of the ore. These assays furnish always a gray cast-iron;
and, therefore, the quality of the products can hardly be judged of,
except by an experiment on the large scale. The temperature necessary
for the success of an assay is about 150° of Wedgewood.

In the assays by the _humid_ way, we may expect to find manganese,
silica, alumina, lime, magnesia, and sometimes carbonic acid, associated
with the iron. 100 grains of the ore in fine powder are to be digested
with nitro-muriatic acid; which will leave only the silica with perhaps
a very little alumina. If an effervescence takes place in the cold with
a dilute acid, the loss of weight will indicate the amount of carbonic
acid gas expelled. The muriatic solution contains the iron, the
manganese, the lime, magnesia, and most of the alumina, with a little
silica. On evaporating to dryness, and digesting in water, all the
silica will remain in an insoluble state. If the solution somewhat
acidulated be treated with oxalate of ammonia, the lime will fall down
in the form of an oxalate; ammonia will now precipitate the alumina and
the oxide of iron together, while the manganese and magnesia will
continue dissolved in the state of triple salts (ammonia-muriates). The
alumina may be separated from the ferric oxide by potash-lye. The
manganese may be thrown down by hydrosulphuret of potash; and, finally,
the magnesia may be precipitated by carbonate of soda. 100 parts of the
red oxide of iron contain 69·34 of metal, and 30·66 of oxygen.

If phosphorus be present in the ore, the nitro-muriatic solution being
rendered nearly neutral, will afford with muriate of lime a precipitate
of phosphate of lime, soluble in an excess of muriatic acid.

When the sole object is to learn readily the per-centage of iron, the
ore may be treated with hot nitro-muriatic, the acid solution filtered,
and supersaturated with ammonia, which will throw down only the iron
oxide and alumina; because the lime is not precipitable by that alkali,
nor is magnesia and manganese, when in the state of ammonia-muriates.
The red precipitate being digested with some potash-lye, will lose its
alumina, and will leave the ferric oxide nearly pure. The presence of
sulphur, phosphorus, or arsenic, in iron ores, may always be detected by
the blowpipe, or ustulation in the assay muffle, as described under
FURNACE.

_Of the smelting of iron-ores._--We shall describe, in the first place,
the methods practised in Great Britain, and shall afterwards consider
those pursued in other countries, in the treatment of their peculiar
ores.

Iron is divided into three kinds, according to the different metallic
states in which it may be obtained; and these are called _crude_ or
_cast iron_; _steel_; and _bar_ or malleable iron. These states are
determined essentially by the different proportions of charcoal or
carbon held in chemical combination; cast iron containing more than
steel, and steel more than malleable iron; which last, indeed, ought to
be the pure metal, a point of perfection, however, rarely if ever
attained. It is impossible to assign the limits between these three
forms of iron, or their relative proportions of carbon, with ultimate
precision; for bar iron passes into steel by insensible gradations, and
steel and cast iron make such mutual transitions as to render it
difficult to define where the former commences, and the latter ceases,
to exist. In fact, some steels may be called crude iron, and some cast
irons may be reckoned among steels.

Towards the conclusion of the last century the manufacture of iron
underwent a very important revolution in Great Britain, by the
substitution of pitcoal for charcoal of wood, the only combustible
previously used in smelting the ores of this metal. This improvement
served not merely to diminish the cost of reduction, but it furnished a
softer cast iron, fit for many new purposes in the arts. From this era,
iron works have assumed an immense importance in our national industry,
and have given birth to many ingenious and powerful machines for
fashioning the metal into bars of every form, with almost incredible
economy and expedition.

The profusion of excellent coal, and its association in many localities
with iron-stone, have procured hitherto for our country a marked
superiority over all others in the iron trade; though now every possible
effort is making by foreign policy to rival or to limit our future
operations. In 1802, M. de Bonnard, now divisionary inspector in the
royal corps of mines of France, and secretary of the general council,
made a tour in England, in order to study our new processes of
manufacturing iron, and published on his return, in the Journal des
Mines, tom. 17., a memoir descriptive of them. Since the peace, many
French engineers and iron-masters have exerted themselves in
naturalizing in France this species of industry; and M. de Gallois, in
particular, after a long residence in Great Britain, where he was
admitted to see deliberately and minutely every department of the iron
trade, returned with ample details, and erected at Saint-Etienne a large
establishment entirely on the English model. More recently, MM. Dufrénoy
and Elie de Beaumont, and MM. Coste and Perdonnet, have published two
very copious accounts of their respective metallurgic tours in Great
Britain, illustrated with plans and sections of our furnaces, for the
instruction of the French nation.

The argillaceous carbonate of iron, or clay ironstone of the coal
measures, is the chief ore smelted in England. Some red hematite is used
as an auxiliary in certain works in Cumberland and Lancashire; but
nowhere is the iron-sand, or other ferruginous matters of the secondary
strata, employed at present for procuring the metal.

Among the numerous coal-basins of England there are two, in particular,
which furnish more than three-fourths of the whole cast iron produced in
the kingdom; namely, the coal field of Dudley, in the south of
Staffordshire; and the coal fields of Monmouthshire, in South Wales,
along with those of Gloucestershire and Somersetshire.

Dudley is peculiarly favoured by nature. There are found associated the
coal, the iron ore, the limestone for flux, and the refractory fire-clay
for constructing the interior brick-work of the furnaces. This famous
clay is mined at Stourbridge, and exported to every part of the kingdom
for making cast-steel crucibles and glass-house melting pots.

At Merthyr-Tydvil, the centre of the iron works of Wales, the iron-stone
is extremely plentiful, forming 16 beds, or rather constituting an
integrant portion of 16 beds of slate-clay. Sometimes it occurs in
pretty long tables adjoining each other, so as to resemble a continuous
stratum; but more frequently it forms nodules of various size and
abundance, placed in planes both above and below the coal seam. Eight
varieties of ore, belonging to different beds, have been distinguished
by the following barbarous names: black balls, black pins, six-inch-wide
vein, six-inch jack, blue vein, blue pins, gray pins, seven pins. The
bed containing the first quality of iron-stone is analogous to the black
ore of Staffordshire called _gubbin_; it is often cleft within like
_septaria_, and its cavities are sometimes besprinkled with crystals of
carbonate of lime or quartz. In the superior beds there are nodules
decomposing into concentric coats, of which the middle is clay. Crystals
of oxide of titanium are occasionally found in the middle of the balls
of clay iron-stone; to which the metallic titanium observed in the
inside of the dome of blast furnaces, may be traced. Both at Dudley and
South Wales, casts of shells belonging to the genus _unio_, are observed
on the iron-stone.

The average richness of the iron-stones of South Wales is somewhat
greater than those of Staffordshire. The former is estimated at 33 parts
of cast iron, while the latter rarely exceeds 30 parts in 100 of ore;
and this richness, joined to the superior quality or cheapness of the
coals, and the proximity of the sea, gives South Wales a decided
advantage as a manufacturing district.

The number of blast furnaces in the parish of Merthyr-Tydvil amounts to
upwards of 30. The cast iron produced is, however, seldom brought into
the market, but is almost entirely converted into bar iron, of which, at
Mr. Crawshay’s works, 600 tons are manufactured in a week. Numerous iron
railways, extending through a length of 220 miles, facilitate the
transport of the materials and the exportation of the products. That
concurrence of favourable circumstances, which we have noticed as
occurring at Dudley, prevails in an equal degree in South Wales.

The same economy which the use of coal has introduced into the smelting
of cast iron from the ore, also extends to its refinery into bars. And
this process would supersede in every iron work the use of wood
charcoal, were not the iron produced by the latter combustible, better
for many purposes, particularly the manufacture of steel. In some
English smelting works, indeed, where sheet iron is prepared for making
tin plate, a mixed refining process is employed, where the cast iron is
made into bar iron by wood charcoal, and laminated by the aid of a coal
fire.

Till 1740, the smelting of iron ores in England was executed entirely
with wood charcoal; and the ores employed were principally brown and red
hematites. Earthy iron ores were also smelted; but it does not appear
that the clay iron-stones of the coal-basins were then used, though they
constitute almost the sole smelting material at the present day. At that
era, there were 59 blast furnaces, whose annual product was 17,350 tons
of cast iron; that is, for each furnace, 294 tons per annum, and 5-1/8
tons per week. By the year 1788, several attempts had been made to
reduce iron ore with coaked coal; and there remained only 24 charcoal
blast furnaces, which produced altogether 13,000 tons of cast iron in
the year; being at the rate of 546 tons for each per annum, or nearly 11
tons per week. This remarkable increase of 11 tons for 5-1/8, was due
chiefly to the substitution of cylinder blowing machines worked with
pistons, for the common wooden bellows. Already 53 blast furnaces fired
with coke were in activity; which furnished _in toto_ 48,800 tons of
iron in a year; which raises the annual product of each furnace to 907
tons, and the weekly product to about 17-1/2 tons. The quantity of

  cast iron produced that year (1788) by means of coal, was 48,800 tons,
            and that by wood charcoal, was                  13,100
                                                            ------
            constituting a total quantity of                61,900 tons.

In 1796, the wood charcoal process was almost entirely given up; when
the returns of the iron trade made by desire of Mr. Pitt, for
establishing taxes on the manufacture, afforded the following results:--

121 blast furnaces, furnishing in whole per annum 124,879 tons,
constituting an average amount for each furnace of 1032 tons.

In 1802, Great Britain possessed 168 blast furnaces, yielding a product
of about 170,000 tons; and this product amounted, in 1806, to 250,000
tons, derived from 227 coke furnaces, of which only 159 were in activity
at once. These blast furnaces were distributed as follows:--

  In the principality of Wales                                      52
  In Staffordshire                                                  42
  In Shropshire                                                     42
  In Derbyshire                                                     17
  In Yorkshire                                                      28
  In the counties of Gloucester, Monmouth, Leicester, Lancaster,
     Cumberland, and Northumberland                                 18
  In Scotland                                                       28
                                                                   ---
                                                                   227

In 1820, the iron trade had risen to the amount shewn in the following
table:--

                                            Tons.
  Wales manufactured, per annum            150,000
  Shropshire and Staffordshire             180,000
  Yorkshire and Derbyshire                  50,000
  Scotland, with some places in England     20,000
                                           -------
  Total                                    400,000

In a statistical view given by M. de Villefosse, of the French and
English iron works, he assigns to the latter, in 1826, 305 blast
furnaces, distributed as follows:--

  In the principality of Wales                   87
  In Staffordshire                               78
  In Shropshire, Derbyshire, Yorkshire, &c.      84
  In Scotland                                    56
                                                ---
                                                305

Out of these, 280 were in activity at the same time; and if we suppose
their mean product to have been 50 tons a week, the total product would
have been, in 1826, 728,000 tons. But this estimate seems to be somewhat
above the truth; for, from the information communicated by Mr. Philip
Taylor to M. Achille Chaper, a considerable French iron-master, who, in
the summer of 1826, inspected two-thirds of the blast furnaces of Great
Britain, their product during this year was about 600,000 tons.

The preceding details shew the successive increments which the
manufacture of cast iron has received; and a similar progression has
taken place in its refinery into wrought iron. This operation was
formerly effected by the agency of wood charcoal in refineries analogous
to those still made use of in France. But when that kind of fuel began
to be scarce in this island, it came to be mixed with coke in various
proportions. The bar iron thus produced was usually hard, and required
much time to convert, so that an establishment which could produce 20
tons of bar iron in a week, was deemed considerable. At that time,
England imported annually from Sweden and Russia the enormous quantity
of 70,000 tons of iron.

Mr. Cort, to whom Great Britain is indebted for the methods now pursued
in this country, succeeded about that time, after many unsuccessful
experiments, in converting cast iron into bar iron, by exposing it on
the hearth of a reverberatory furnace to the flame of pitcoal. This
method, which possessed the advantage of employing this species of
combustible alone, likewise simplified the treatment, because it
required no blast apparatus. But this mode of refinery, consisting in
the use of a reverberatory furnace alone, did not produce altogether the
desired result. It was irregular; sometimes the loss of iron was small,
but at others it was very considerable; and there were great variations
in the quality of the iron, as well as in the quantity of fuel consumed.
Mr. Cort succeeded in removing this uncertainty of result, by causing
the puddling in the reverberatory furnace to be preceded by a kind of
refinery with coke. The intent of this operation was to decarburate the
iron, and to prepare it for becoming malleable. The metal took in that
case the name of _finery_ metal, called, for sake of brevity,
_fine-metal_.

He also substituted the drawing cylinders for the extension under the
hammer, an improvement which accelerated greatly the manufacture of bar
iron. The iron then yielded by the operation of puddling, was of a very
inferior quality, and could not be directly employed in the arts. In
order to give it more consistence, it was subjected to a second heating
in a reverberatory furnace; and whenever this method had arrived at a
high enough degree of perfection to afford products fit for the market,
it became exclusively employed in Great Britain. This new method of
transforming cast-iron into malleable iron, speedily gained such an
extension, that of late years, a single iron-work, Cyfartha in Wales,
manufactured annually more than twice as much as was made annually from
1740 to 1750, in the whole kingdom.

In surveying the improvements which the iron manufacture has received in
England in the space of the last 60 years, they are seen to be
resolvable into two; the first set relating to the smelting of the ores;
the other, to the conversion of the pigs into bar iron; hence naturally
arise two heads under which the subject of iron must be treated.

1. _Manufacture of cast-iron by coke and coal._--The cast-iron produced
by the English and Scotch blast furnaces is in general black and very
soft; but yet may be distinguished into several qualities, of which
three are particularly noticed.

No. 1. _Very black cast-iron_, in large rounded grains, obtained
commonly near the commencement of the casting, when an excess of carbon
is present; in flowing, it appears pasty, and throws out blue
scintillations. It exhibits a surface where crystalline vegetations
develope themselves rapidly in very fine branches; it congeals or fixes
very slowly; its surface when cold is smooth, concave, and often charged
with plumbago; it has but a moderate tenacity, is tender under the file,
and susceptible of a dull polish. When melted over again, it passes into
No. 2., and forms the best castings.

No. 2. _Black cast-iron_, has a somewhat lighter shade than the
preceding, and may therefore on comparison be called blackish-gray. It
presents less large granulations than No. 1.; is tenacious, easily
turned, filed, and polished; excellent for casting when it approaches to
No. 1., and for the manufacture of bar iron when it has on the contrary
a shade somewhat lighter. If repeatedly melted, it passes into the next
quality, or

No. 3. _White cast-iron_; this is brittle, and indicates always some
derangement in the working of the furnace; it flows imperfectly, and
darts out in casting, abundance of brilliant white scintillations; it
fixes very quickly; and on cooling, exhibits on its surface irregular
asperities, which make it extremely rough. It is easily broken, and
presents a lamellar and radiated fracture; and is so hard that tempered
steel cannot act upon it. It is cast only into weights, bullets or
bombs, but never into pieces of machinery. When exposed to the refinery
processes, it affords a bad bar iron. It is owing probably to the
different nature of the cast-iron obtained in different counties in
England, that Staffordshire and Shropshire furnish the greater part of
the great iron castings, while Wales manufactures almost exclusively
malleable iron. The lower price of coals in Wales is perhaps the cause
to a certain extent of this difference in the results of these two iron
districts. It will be interesting at any rate, to describe separately
the processes employed in Staffordshire and Wales.

_The blast furnaces of Staffordshire_, in the neighbourhood of Dudley,
Bilston, and Wednesbury, are constructed almost wholly of bricks. Their
outer form is frequently a cone, often also a pyramid with a square
base. They are bound about with a great many iron hoops, or with iron
bars placed at different heights. This powerful armour allows the
furnaces to be built much less massively than they formerly were; and
admits of lighter and more elegant external forms. They are seldom
insulated; but are usually associated to the number of two or three in
the same line. A narrow passage is left between them, which leads to the
lateral openings where the tuyères are placed. At the front of the
furnace, a large shed is always raised. The roofs of these sheds present
in general circular profiles, and being made of cast or bar iron, they
display a remarkable lightness of construction. The cast-iron columns
likewise, which support the joists and girders, give additional
elegance.

[Illustration: 582]

In the Dudley field, the furnaces are almost always in the middle of the
plain, and an inclined rail-way must be formed to reach their platform.
These inclined planes, composed of beams or rails placed alongside of
each other, and sustained by props and cross-bars, as indicated in
_fig._ 582., are set up mostly against the posterior face of the
furnace. Two chains or ropes, passing over the drums of gins, moved by a
steam engine (commonly the same that drives the bellows), draw up the
waggons of wood or sheet iron _a a_, which contain the various materials
for supplying the furnace. To facilitate this service, the platform
round the furnace is sometimes enlarged behind by a floor; while a
balustrade, which opens when the waggons arrive at the platform,
prevents accidents. This projection is occasionally covered by a roof.
For a furnace of the largest size, the force expended by this lifting
apparatus, is not more than a two-horse power.

_Fig._ 582. is a vertical section through the furnace from front to
rear, or at right angles to the line of the lateral tuyères. The
erection of a pair of blast furnaces, of 40 feet high each, costs, in
the Dudley district, 1800 pounds sterling; and requires for building
each, 160,000 common bricks for the outside work, 3900 fire-bricks for
the lining or shirt of the furnace, and 825 for the boshes. The
dimensions of the fire-bricks are various; 5 kinds are employed for the
lining, and 9 kinds for the boshes. They are all 6 inches thick, and are
curved to suit the _voussoirs_.

The number of charges given in 12 hours is different in different
furnaces; being sometimes 20, 25, and even so high as 40; but 30 is a
fair average. Each charge is composed of from 5 to 6 cwt. of coak, (or
now of 3 to 4 cwt. of coal with the hot blast); 3, 4, and sometimes 6
cwt. of the roasted mine, according to its richness and the quality of
cast iron wanted; the limestone flux is usually one-third of the weight
of the roasted iron stone. There are 2 casts in 24 hours; one at 6 in
the morning, and another at 6 in the evening.

The height of the blast furnaces is very variable; some being only 36
feet high including the chimney, whilst others have an elevation of 60
feet. These extreme limits are very rare: so that the greater part of
the furnaces are from 45 to 50 feet high. They are all terminated by a
cylindrical chimney of from 8 to 12 feet long; being about one-fifth of
the total height of the furnace. The inside diameter of this chimney is
the same as that of the throat or mouth; and varies from 4 to 6 feet.
The chimney is frequently formed of a single course of bricks, and
acquires solidity from its hoops of iron, so thickly placed that one
half of the surface is often covered with them. At its lower end, the
mouth presents one or two rectangular openings, through which the charge
is given. It is built on a basement circle of cast-iron, which forms the
circumference of the throat; and a sloping plate of cast-iron _b_ is so
placed as to make the materials slide over into the furnace, as shown in
the figure.

The inside of the blast furnaces of Staffordshire is most frequently of
a circular form, except the hearth and working area. The inner space is
divided into four portions, different in their forms, and the functions
which they fulfil in the smelting of the ore.

The undermost, called the hearth, or crucible, in which the cast-iron
collects, is a right rectangular prism, elongated in a line
perpendicular to the axes of the tuyères. The sides of the hearth
consist in general of refractory sandstone (fire-stone), obtained mostly
from the bed of the coal basin, called _millstone grit_; and the bottom
of the hearth is formed of a large block of the same nature, laid on a
cast-iron plate.

The second portion is also made of the same refractory grit stone. It
has the form of a quadrangular pyramidal, approaching considerably to a
prism, from the smallness of the angle included between the sides and
the axis.

The third portion or lower body of the furnace is conical, but here the
interior space suddenly expands; the slope outwards at this part seems
to have a great influence on the quality of the cast-iron obtained from
the furnace. When No. 2. of the blackest kind is wanted for castings,
the inclination of this cavity of the furnace is in general less
considerable than when No. 2. cast iron for conversion into bar iron is
required. The inclination of this conical chamber, called the boshes,
varies from 55 to 60 degrees with the horizon. The diameter of this part
is equal to that of the belly, and is from 11 to 13 feet. The boshes are
built of masonry, as shown in _figs._ 583, 584.

The fourth part, which constitutes about two-thirds of the height of the
furnace from the base of the hearth up to the throat, presents the
figure of a surface of revolution, generated by a curve whose concavity
is turned towards the axis of the furnace, and whose last tangent
towards the bottom is almost vertical. This surface is sloped off with
that of the boshes (_étalages_ in French), so that no sharp angle may
exist at the belly. In some furnaces of considerable dimensions, as in
that with three tuyères, this portion of the furnace is cylindrical for
a certain height.

The following measurements represent the interior structure of two
well-going furnaces.

  +---------------------------------------------+-------+-------+
  |                                             | No. 1.| No. 2.|
  +---------------------------------------------+-------+-------+
  |                                             |_Feet._|_Feet._|
  |Height from the hearth to the throat or mouth| 45    | 49    |
  |Height of the crucible or hearth             |  6-1/2|  6    |
  |       of the boshes                         |  8    |  7    |
  |       of the cone                           | 30-1/2| 36    |
  |       of the chimney or mouth               |  8    | 12-3/4|
  |Width of the bottom of the hearth            |  2-1/2|  2    |
  |Ditto at its upper end                       |  3    |  2-2/3|
  |Ditto of the boshes                          | 12-2/3| 13-1/2|
  |Ditto at one-third of the belly              | 12    | 11-1/2|
  |Ditto at two-thirds of ditto                 |  8-2/3|  9-1/2|
  |Ditto at the mouth                           |  4-1/2|  3-2/3|
  |Inclination of the boshes                    | 59°   | 52°   |
  +---------------------------------------------+-------+-------+

[Illustration: 583]

The conical orifice called the tuyère, in which the tapered pipes are
placed, for imparting the blast, is seen near the bottom of the furnace,
_fig._ 583. at A. Nose tubes of various sizes, from 2 to 4 inches in
diameter, are applied to the extremity of the main blast-pipe. Under A
is the bottom of the hearth, which, in large furnaces, may be two feet
square. B is the top of the hearth, about two feet six inches square. A,
B, is the height of the hearth, about six feet six inches. B shows the
round bottom of the conical or funnel part, called in this country, the
_boshes_, standing upon the square area of the hearth. C is the top of
the boshes, which may be about 12 feet in diameter, and 8 feet in
perpendicular height. D is the furnace top or mouth (_gueulard_ in
French), at which the _materials are charged_. It may be 4-1/2 feet in
diameter. The line between C, D, is the height of the internal cavity of
the furnace, from the top of the boshes upwards, supposed to be 30 feet.
A, D, is the total height of the interior of the furnace, reckoned at
44-1/2 feet. E E is the lining, which is built in the nicest manner with
the best fire-bricks, from 12 to 14 inches long, 3 inches thick, and
curved to suit the circle of the cone. A vacancy of 3 inches wide is
left all round the outside of the first lining by the builder; which is
sometimes filled with coak dust, but more generally with sand firmly
rammed. This void space in the brick-work is for the purpose of allowing
for any expansion which might occur, either by an increase in the bulk
of the building, or by the pressure and weight of the materials when
descending to the bottom of the furnace. Exterior to E E is a second
lining of fire-bricks similar to the first. At F, on either side, is a
cast-iron lintel, 8-1/2 feet long, by 10 inches square, upon which the
bottom of the arches is supported. F, G, is the rise of the tuyère arch,
which may be 14 feet high upon the outside, and 18 feet wide. The
extreme size of the bottom or sole of the hearth, upon each side of A,
may be 10 feet square. This part and the boshing stones, are preferably
made from a coarse sandstone grit, containing large rounded grains of
quartz, united by a siliceo-argillaceous cement.

The bottom of the hearth consists, first, of a course of the said
gritstone; beneath which is a layer of bedding sand, having, in its
under part, passages for the escape of the vapours generated by damps;
the whole being supported upon pillars of brick.

[Illustration: 584]

_Fig._ 584. represents the hearth and boshes, in a vertical side
section. _a_ is the tymp stone, and _b_ the tymp plate for confining the
liquid metal in the hearth. The latter is wedged firmly into the
side-walls of the hearth; _c_ is the dam-stone, which occupies the whole
breadth at the bottom of the hearth, excepting about 6 inches, which
space, when the furnace is at work, is filled before every cast, with a
strong binding sand. This stone is faced outside by a cast-iron plate
_d_, called the dam-plate, of considerable thickness, and peculiar
shape. The top of the dam-stone, or rather the notch of the dam-plate,
lies from 4 to 8 inches under the level of the tuyère hole. The space
under the tymp plate, for 5 or 6 inches down, is rammed full, for every
cast, with strong loamy earth, or even fine clay; a process called the
tymp stopping. The area of the base of this furnace being 38 feet; its
extreme height is 55 feet.

The blast furnaces of Staffordshire have always two tuyères, at least,
placed on opposite sides, but so pointed that the blast may not pursue
directly opposite lines. In a furnace acting well in the neighbourhood
of Dudley, the one of the tuyères was 10 inches distant from the
posterior wall of the hearth, and the other only 4 inches. In other
furnaces with 3 tuyères; the side ones are placed, the one 16-1/2
inches, and the other 6-1/2 inches from the back. Three tuyères are
seldom made to blow simultaneously. The third is brought into action
only when the furnace seems to be choaked up, and when it becomes
necessary to clear it up by a powerful concussion. Too much pains cannot
be bestowed on the masonry and brickwork of a blast furnace, and on the
solidity of its foundation. In a soft ground it should rest on piles, so
driven that the channel left beneath for the drainage of the building
may be above any water level. Small passages should likewise be left
throughout the body of the work, for the transpiration of moisture.

The blowing machines employed in Staffordshire, are generally cast-iron
cylinders, in which a metallic piston is exactly fitted as for a steam
engine, and made in the same way. Towards the top and bottom of the
blowing cylinders orifices are left covered with valves, which open
inside when the vacuum is made with the cylinders, and afterwards shut
by their own weight. Adjutages conduct into the iron globe or chest, the
air expelled by the piston, both in its ascent and descent; because
these blowing machines have always a double stroke.

The pressure of the air is made to vary through a very considerable
range, according to the nature of the fuel and season of the year; for
as in summer the atmosphere is more rarefied, it must be expelled with a
compensating force. The limits are from 1-1/2 pounds to 3-1/2 pounds on
the inch; but these numbers represent extreme proportions, the average
amount in Staffordshire being 3 pounds. With this pressure a furnace
usually works, which affords 60 tons of cast iron in the week; and the
pressure may be 2-1/2 pounds on an average. The orifices, or nose-pipes,
through which the air issues, also vary with the nature of the coke and
the ore. In Staffordshire they are generally from 2 inches and 5 tenths
to 2 inches and 8 tenths in diameter.

The blowing machines of Staffordshire are always impelled by steam
engines. At Mr. Bagnall’s works, two blast furnaces, 40 feet high,
exclusive of the chimney or top, and two finery furnaces, are worked by
a steam engine of 40 horses power; and therefore the power of one horse
corresponds to the production of 2-1/2 tons of cast iron per weekly,
independently of the finery.

In South Wales, especially at Pontypool, there are slighter blast
furnaces, whose upper portion is composed of a single range of bricks,
each of which is 20 inches long, 4 thick, and 9 broad. The interior of
the chimney represents an inverted cone. These furnaces derive solidity,
and power to resist the expansions and contractions from change of
temperature, by being cased, as it were, in horizontal hoops, placed 3
feet, or, even in some cases, only 6 inches asunder. These flat rings
consist of four pieces, which are joined by means of vertical bars, that
carry a species of ears or rings, into which the hoops enter, and are
retained by bolts or keys. Instead of these ears, screw nuts are also
employed for the junction. Each hoop is alternately connected to each of
the eight vertical bars. The interior of these furnaces is the same as
of the others; being generally from 12 to 14 feet diameter at the belly,
and from 50 to 55 feet high. Though slight, they last as long as those
composed of an outer body of masonry and a double lining of bricks; and
have continued constantly at work for three years. In Wales also the
blast furnaces are generally somewhat larger than in Staffordshire;
because there the object being to refine the cast iron, they wish to
procure as large a smelting product as possible. But in Staffordshire, a
fine quality of casting iron is chiefly sought after, and hence their
furnaces have less height, but nearly the same width.

In a blast apparatus employed at the Cyfartha works, moved by a 90-horse
steam power, the piston rod of the blowing cylinder is connected by a
parallelogram mechanism with the opposite end of the working beam of the
steam engine. The cylinder is 9 feet 4 inches diameter, and 8 feet 4
inches high. The piston has a stroke 8 feet long, and it rises 13 times
in the minute. By calculating the sum of the spaces percurred by the
piston in a minute, and supposing that the volume of the air expelled is
equal to only 96 per cent. of that sum, which must be admitted to hold
with machines executed with so much precision, we find that 12,588 cubic
feet of air are propelled every minute. Hence a horse power applied to
blowing machines of this nature gives, on an average, 137 cubic feet of
air per minute. The pressure on the air as it issues, rarely exceeds two
pounds on the square inch in the Welsh works.

At the establishment of Cyfartha, for blowing seven smelting furnaces,
and the seven corresponding fineries, three steam engines are employed,
one of 90 horse-power, another of 80, and a third of 40; which
constitutes in the whole, a force of 210 horses, or 26 horses and 1/5
_per furnace_, supposing the fineries to consume one-eighth of the
blast. In the whole of the works of Messrs. Crawshay, the proprietors of
Cyfartha, the power of about 350 horses is expended in blowing 12
smelting furnaces, and their subordinate fineries; which gives from 25
to 26 horses for each, allowing as before one-eighth for the fineries.
As these furnaces produce each about 60 tons of cast iron weekly, we
find that a horse power corresponds to 2 tons and a tenth in that time.
Each of the furnaces consumes about 3567 cubic feet of air per minute.
These works have been greatly increased of late years.

The following analyses of the English coal ironstones have been made by
M. Berthier, at the school of mines in Paris.

  +------------------+----------+----------+-------------------+
  |                  |Rich Welsh|Poor Welsh|Rich ore of Dudley,|
  |                  |   ore.   |   ore.   |    or _gubbin_.   |
  +------------------+----------+----------+-------------------+
  |Loss by ignition  |   30·00  |   27·00  |      31·00        |
  |Insoluble residuum|    8·40  |   22·03  |       7·66        |
  |Lime              |    0·0   |    6·00  |       2·66        |
  |Peroxide of iron  |   60·00  |   42·66  |      58·33        |
  |                                                            |
  |On calculating the quantities of carbonate of iron, and me- |
  |tallic iron, to which the above peroxide corresponds, we    |
  |have:--                                                     |
  |                                                            |
  |Carbonate of iron |   88·77  |   65·09  |      85·20        |
  |Metallic iron     |   42·15  |   31·38  |      40·45        |
  +------------------+----------+----------+-------------------+

The mean richness of the ores of carbonate of iron of these coal basins,
is not far from 33 per cent. About 28 _per cent._ is dissipated on an
average, in the roasting of the ores.

Every ferruginous clay-stone is regarded as an iron ore, when it
contains more than 20 per cent. of metal; and it is paid for according
to its quality, being on an average at 12 shillings per ton in
Staffordshire. The gubbin however fetches so high a price as 16 or 17
shillings. The ore must be roasted before it is fit for the blast
furnace, a process carried on in the open air. A heap of ore mingled
with small coal (if necessary) is piled up over a stratum of larger
pieces of coal; and this heap may be 6 or 7 feet high, by 15 or 20
broad. The fire is applied at the windward end, and after it has burned
a certain way, the heap is prolonged at the other extremity, as far as
the nature of the ground or convenience of the work requires. The
quantity of coal requisite for roasting the ore varies from one to four
hundred weight per ton, according to the proportion of bituminous matter
associated with the iron-stone. The ore loses in this operation from 25
to 30 per cent. of its weight. Three and a quarter tons of crude ore, or
two and a quarter tons of roasted ore are required to produce a ton of
cast iron; that is to say, the crude material yields on an average 30·7
per cent., and the roasted ore 44·4 of pig metal. In most smelting works
in Staffordshire, about equal weights of the rich ore in round nodules
called _gubbin_, and the poorer ore in cakes called _blue flat_, are
employed together in their roasted state; but the proportions are
varied, in order to have an uniform mixture, capable of yielding from 30
to 33 per cent. of metal.

The transition or carboniferous limestone of Dudley is used as the flux;
it is compact and contains little clay. The bulk of the flux is made
nearly equal to that of the ore. To treat two tons and a quarter of
roasted ore, which furnish one ton of pig iron, 19 hundred weight of
limestone are employed; constituting nearly 1 of limestone for 3 of
unroasted ore. The limestone costs 6 shillings the ton.

Carbonized pitcoal or coke was, till within these few years, the sole
combustible used in the blast furnaces of Staffordshire.

The coal is distributed in circular heaps, about 5 feet diameter, by 4
feet high; and the middle is occupied by a low brick chimney, piled with
loose bricks, so open as to leave interstices between them, especially
near the ground. The larger lumps of coal are arranged round this
chimney, and the smaller towards the circumference of the heap. When
every thing is adjusted, a kindling of coals is introduced into the
bottom of the brick chimney; and to render the combustion slow, the
whole is covered over with a coat of coal dross, the chimney being
loosely closed with a slab of any kind. Openings are occasionally made
in the crust and afterwards shut up, to quicken and retard the ignition
at pleasure, during its continuance of 24 hours. Whenever the
carbonization has reached the proper point for forming good coke, the
covering of coal dross is removed, and water is thrown on the heap to
extinguish the combustion; a circumstance deemed useful to the quality
of the coke. In this operation the Staffordshire coal loses the half of
its weight, or two tons of coal produce one of coke.

As soon as the blast furnace gets into a regular heat, which happens
about 15 days or three weeks after fires have been put in it, the
working consists simply in charging it, at the opening in the throat,
whenever there is a sufficient empty space; the only rule being to keep
the furnace always full. The coke is measured in a basket, thirteen of
which go to the ton. The ore and the flux (limestone) are brought
forwards in wheelbarrows of sheet-iron. In 24 hours, there are thrown
into a furnace such as _fig._ 582., 14-1/3 tons of coke, 16 tons of
roasted ore, and 6-3/4 tons of limestone; from which about 7 tons of pig
iron are procured. This is run off every 12 hours; in some works the
blast is suspended during the discharge. The metal intended to be
converted into bar iron, or to be cast again into moulds, is run into
small pigs 3 feet long, and 4 inches diameter; weighing each about 2
hundred weight and a half.

The disorders to which blast furnaces are liable, have a tendency always
to produce white cast iron. The colour of the slag or scoriæ is the
surest test of these derangements, as it indicates the quality of the
products. If the furnace is yielding an iron proper for casting into
moulds, the slag has an uniform vitrification, and is slightly
translucid. When the dose of ore is increased in order to obtain a gray
pig iron, fit for fabrication into bars, the slag is opaque, dull, and
of a greenish-yellow tint, with blue enamelled zones. Lastly, when the
furnace is producing a white metal, the slags are black, glassy, full of
bubbles, and emit an odour of sulphuretted hydrogen. The scoriæ from a
coke, are much more loaded with lime than those from a charcoal blast
furnace. This excess of lime appears adapted to absorb and carry off the
sulphur, which would otherwise injure the quality of the iron. The
slags, when breathed on, emit an argillaceous odour.

A blast furnace of 50 or 60 feet in height, gives commonly from 60 to 70
tons of cast iron per week; one from 50 to 55 feet high, gives 60 tons;
two united of 45 feet, produce together, 100 tons; and one of 36 feet
furnishes from 30 to 40. A blast furnace should go for four or five
years without needing restoration. From 3-1/2 to 4 tons of coal,
inclusive of the coal of calcination, are required in Staffordshire to
obtain one ton of cast iron; and the expense in workmen’s wages is about
15 shillings on that quantity.

At the Cyfartha works of Messrs. Crawshay in South Wales, the average
price of the lithoid carbonate of iron, ready for roasting, is only
7_s._ 6_d._ a ton, and its richness is about 33 _per cent._ The furnaces
for roasting the ore in that country are made in the form of cylinders,
placed above an inverted cone. The cylindrical part is 6 feet high and
wide, and the cone is about 4 feet high, with a base equal to that of
the cylinder; towards the bottom or narrowest part of the inverted cone,
there is an aperture which terminates in an outlet on a level with the
bottom of the terrace in which the furnace is built. Sometimes, however,
all the roasting furnaces are in a manner combined into one, which
resembles a long pit about 6 feet in width and depth, and whose bottom
presents a series of inverted hollow quadrangular pyramids, 6 feet in
each side, and 4 deep. The bottom or apex of each of these pyramids,
communicates with a mouth or door-way that opens on a lower terrace,
through which the ore falls in proportion as it is roasted; and whence
it is wheeled and tumbled into the throat of an adjoining blast furnace,
on the same level with the terrace; for in Wales the blast furnace is
generally built up against the face of a hill, which makes one of its
fronts. The above roasting furnaces, which closely resemble lime-kilns,
after being filled with alternate strata of small coal and ore, are set
on fire; and the roasted ore is progressively withdrawn below, as
already mentioned.

The product of coke from a certain weight of coal is greater in Wales
than in Staffordshire, though the mode of manufacture is the same. At
Pen-y-Darran, for example, 5 of coal furnish 3-1/2 of coke; or 100 give
70; at Dowlais 100 of coal afford 71 of coke, and the product would be
still greater if more pains were bestowed upon the process. At Dowlais,
coal costs only 2 shillings a ton; at Cyfartha, it is worth from 2_s._
6_d._ to 5 shillings. About 2 tons of coke are employed in obtaining 1
ton of cast iron.

According to M. Berthier’s analysis, the slag or cinder of Dowlais
consists of silica, 40·4; lime, 38·4; magnesia, 5·2; alumina, 11·2;
protoxide of iron, 3·8; and a trace of sulphur. He says that the silica
contains as much oxygen as all the other bases united; or is equivalent
to them in saturating power; and to the excess of lime he ascribes the
freedom from sulphur, and the good quality of the iron produced. The
specimen examined was from a furnace at Merthyr-Tydvil. Other slags from
the same furnace, and one from Dudley, furnished upwards of 2 _per
cent._ of manganese. Those which he analysed from Saint Etienne in
France afforded about 1 per cent. of sulphur.

The consumption of coal in the Welsh smelting furnaces may be estimated,
on an average, at 3 tons per ton of cast iron; corresponding to 2·1 of
their coke. From this economy in the quantity of fuel, as well as from
its cheapness and that of the iron ore, the iron of South Wales can be
brought into the market at a much lower rate than that of any other
district. These blast furnaces remain in action from 5 to 10 years; at
the end of which time only their interior surface has to be repaired.
The lining of the upper part lasts much longer; for examples are not
wanting of its holding good for nearly 40 years.

One of the greatest improvements ever made by simple means in any
manufacture is the employment of hot air instead of the ordinary cold
air of the atmosphere, in supplying the blast of furnaces for smelting
and founding iron. The discovery of the superior power of a hot over a
cold blast in fusing refractory lumps of cast iron, was accidentally
observed by my pupil Mr. James Beaumont Neilson, engineer to the Glasgow
gas works, about the year 1827, at a smith’s forge in that city, and it
was made the subject of a patent in the month of September of the
following year. No particular construction of apparatus was described by
the inventor by which the air was to be heated, and conveyed to the
furnace; but it was merely stated that the air may be heated in a
chamber or closed vessel, having a fire under it, or in a vessel
connected in any convenient manner with the forge or furnace. From this
vessel the air is to be forced by means of bellows into the furnace. The
quantity of surface which a heating furnace is required to have for a
forge, is about 1260 cubic inches; for a cupola furnace, about 10,000
cubic inches. The vessel may be enclosed in brickwork, or fixed in any
other manner that may be found desirable, the application of heated air
in any way to furnaces or forges, for the purposes of working iron,
being the subject claimed as constituting the invention.

Wherever a forced stream of air is employed for combustion, the
resulting temperature must evidently be impaired by the coldness of the
air injected upon the fuel. The heat developed in combustion is
distributed into three portions; one is communicated to the remaining
fuel, another is communicated to the azote of the atmosphere, and to the
volatile products of combustion, and a third to the iron and fluxes, or
other surrounding matter to be afterwards dissipated by wider diffusion.
This inevitable distribution takes place in such a way, that there is a
nearly equal temperature over the whole extent of a fire-place, in which
an equal degree of combustion exists.

We thus perceive that if the air and the coal be very cold, the portions
of heat absorbed by them might be very considerable, and sufficient to
prevent the resulting temperature from rising to a proper pitch; but if
they were very hot they would absorb less caloric, and would leave more
to elevate the common temperature. Let us suppose two furnaces charged
with burning fuel, into one of which cold air is blown, and into the
other hot air, in the same quantity. In the same time, nearly equal
quantities of fuel will be consumed with a nearly equal production of
heat; but notwithstanding of this, there will not be the same degree of
heat in the two furnaces, for the one which receives the hot air will be
hotter by all the excess of heat in its air above that of the other,
since the former air adds to the heat while the latter abstracts from
it. Nor are we to imagine that by injecting a little more cold air into
the one furnace, we can raise its temperature to that of the other. With
more air indeed we should burn more coals in the same time, and we
should produce a greater quantity of heat, but this heat being diffused
proportionally among more considerable masses of matter, would not
produce a greater temperature; we should have a larger space heated, but
not a greater intensity of heat in the same space.

Thus, according to the physical principles of the production and
distribution of heat, fires fed with hot air should, with the same fuel,
rise to a higher pitch of temperature than fires fed with common cold
air. This consequence is independent of the masses, being as true for a
small stove which burns only an ounce of charcoal in a minute, as for a
furnace which burns a hundred weight; but the excess of temperature
produced by hot air cannot be the same in small fires as in great;
because the waste of heat is usually less the more fuel is burned.

This principle may be rendered still more evident by a numerical
illustration. Let us take, for example, a blast furnace, into which 600
cubic feet of air are blown per minute; suppose it to contain no ore but
merely coal or coke, and that it has been burning long enough to have
arrived at the equilibrium of temperature, and let us see what excess of
temperature it would have if blown with air of 300° C. (572° F.),
instead of being blown with air at 0° C.

600 cubic feet of air under the mean temperature and pressure, weigh a
little more than 45 pounds avoirdupois; they contain 10·4 pounds of
oxygen, which would burn very nearly 4 pounds of carbon, and disengage
16,000 times as much heat as would raise by one degree cent. the
temperature of two pounds of water. These 16,000 portions of heat,
produced every minute, will replace 16,000 other portions of heat,
dissipated by the sides of the furnace, and employed in heating the
gases which escape from its mouth. This must take place in order to
establish the assumed equilibrium of caloric.

If the 45 pounds of air be heated beforehand up to 300° C., they will
contain about the eighth part of the heat of the 16,000 disengaged by
the combustion, and there will be therefore in the same space one eighth
of heat more, which will be ready to operate upon any bodies within its
range, and to heat them one eighth more. Thus the blast of 300° C. gives
a temperature which is nine-eighths of the blast at zero C., or at even
the ordinary atmospheric temperature; and as we may reckon at from 2200°
to 2700° F. (from 1200° to 1500° C.), the temperature of blast furnaces
worked in the common way, we perceive that the hot-air blast produces an
increase of temperature equal to from 270° to 360° F.

Now in order to appreciate the immense effects which this excess of
temperature may produce in metallurgic operations, we must consider that
often only a few degrees more temperature are required to modify the
state of a fusible body, or to determine the play of affinities dormant
at lower degrees of heat. Water is solid at 1° under 32° F.; it is
liquid at 1° above. Every fusible body has a determinate melting point,
a very few degrees above which it is quite fluid, though it may be
pasty below it. The same observation applies to ordinary chemical
affinities; charcoal, for example, which reduces the greater part of
metallic oxides, begins to do so only at a determinate pitch of
temperature, under which it is inoperative, but a few degrees above, it
is in general lively and complete. It is unnecessary, in this article,
to enter into any more details to show the influence of a few degrees of
heat, more or less, in a furnace, upon chemical operations, or merely
upon physical changes of state.

These consequences might have been deduced long ago, and industry might
thus have been enriched with a new application of science; but
philosophers have been and still are too much estranged from the study
of the useful arts, and content themselves too much with the minutiæ of
the laboratory or theoretic abstractions. Within the space of 7 years,
the use of the hot blast has been so much extended in Great Britain, as
to have enabled many proprietors of iron works to add 50 per cent. to
their weekly production of metal, to diminish the expenses of smelting
by 50 per cent., and, in many cases, to produce a better sort of cast
iron from indifferent materials.

[Illustration: 585]

The figures here given represent the blast furnace, and all the details
of the air-heating at one view. _Fig._ 583. is a vertical section of the
furnace and the apparatus; _fig._ 585. represents the plan at the height
of the line 1, 2. of _fig._ 583. The blowing machine, which is not shown
in this view, injects the air through the pipe A, into the regulator
chamber R, _fig._ 585.; the air thence issues by the pipe B, proceeds to
C, where it is subdivided into two portions; the one passes along the
pipe C D to get to the tuyère T, the other passes behind the furnace,
and arrives at the tuyère T´ by the pipe C E F.

These pipes are distributed in a long furnace or flue, whose bottom,
sides, and top are formed with fire-brick, where they are exposed to the
action of the flame of the three fires X, Y, Z. The flame of the fire X
plays round the pipe B at its entrance into the flue, and quits it only
to go into the chimney H; that of the fire Y acts from the point D to
the same chimney, passing by the elbow C; that of the fire Z acts
equally upon F and H, in passing by the elbow E.

[Illustration: 589]

_Disposition of the fires and furnace._--_Fig._ 586. represents, upon a
scale three times larger than _fig._ 585., the section of the fire X,
of which the plan is seen in _fig._ 585., and the elevation in _fig._
583.; as also in the outside view of the blast furnace, _fig._ 589.

[Illustration: 586]

The grate is at L; the fuel is introduced by the door P, _fig._ 583.;
the flame rises above the bridge I K, and proceeds along the vaulted
flue towards the chimney H. Through a length of about 13 feet including
the grate, the furnace is on each side supported by oblong plates of
cast iron, which are bound together by 4 upright ribbed or feathered
bars, also on each side; these bars _n_ being bound together by iron
rods furnished with screw nuts at their ends (_figs._ 583, 585, 586.)
Beyond this distance, the outside of the furnace is mere brickwork.

The fires Y and Z have exactly a like disposition with the above.

[Illustration: 587]

_Fig._ 586. indicates the dimensions and the curvature of the arch above
the grate, near the bridge; _fig._ 587. represents the section of the
furnace and of the pipe beyond the cast-iron casing.

I find that the furnace is only about 3 feet wide at the bottom, and
that the elevation of the arch above the bottom is no more than 30
inches. Perhaps it might be made a little wider with advantage; the
combustion would be more vigorous and effective; and if the sides also
were a little thicker, the heat would be better confined.

  The distance from the fire-place X to the chimney H, is 43-1/2 feet.
                                   Y to the point C, is   13     ----
                                   Z to the chimney, is   29     ----
                                   including the turn of the elbow E.

[Illustration: 588]

_Distribution of the pipes._--At B, the pipe is 18 inches diameter
outside, and one inch thick of metal, and it tapers to C; from C to D
and from D to C the pipes are only 11 inches in external diameter, and
three-fourths of an inch thick; they are 5 feet long, and are united by
two kinds of joints; the ordinary ones, and those of compensation, to
give play for the expansion and contraction. One of these is seen
between B and C, one between C and D, one between C and E, and a fourth
between E and F. These pipes and their adjustment are seen more at large
in _fig._ 588.; U V is one of these pipes, its widened mouth receives
the extremity M of the preceding pipe. These pieces are truly bored and
turned to fit each other, and slide out and in like telescope tubes, by
the effect of dilatation and contraction of the pipes with changes of
temperature.

At certain distances castors or friction-rollers of cast iron are placed
to carry the pipes, which roll upon oblong plates of cast iron laid upon
the floor of the flues. These castors are shown at _a_, _b_, _c_, _d_,
_e_, _f_, _g_, _fig._ 585.; one of them is shown separate upon a larger
scale at G, _fig._ 587., as also the plate or rail S, on which it runs.

The tuyères T T´ are adjusted into the pipe behind them; this is truly
bored, so as to allow the thick end of the tuyère to slide tightly
backwards and forwards in it, like a piston in the barrel of a pump; a
diaphragm moreover prevents the tuyère from being drawn or forced
entirely out of its tube. At the side of this tube there is a small
orifice, which may be shut or opened at pleasure with a stopcock or
screw-plug: it serves to try the degree of heat of the air-blast; if a
lead wire does not melt when held at this hole, the temperature is
reckoned too low; being under the 612th degree of Fahrenheit. The
nozzles are 2 inches in diameter.

Near the fire-places of the air-heating furnaces the pipes are at a
cherry-red heat; and lest they should be burned, they are there coated
with a lute of fire-clay, as shown near K _fig._ 586. By this means the
air is kept up at the heat of 350° C, or 662° F., a little above the
boiling point of quicksilver.

_Quantity of air and pressure._--The blowing-machine belonging to the
above blast-furnace is moved by a water wheel of 22-horse power, the
pistons are 4 feet in diameter, have a 3-1/2-feet stroke, work double,
and expel 1200 cubic feet of air in the minute; or 600 cubic feet for
each nozzle. The pressure of the air is equivalent to no more than 2 or
2-1/4 inches of mercury; formerly with cold air it amounted to 3-1/2
inches. This furnace yields, upon an average, 5-1/4 tons of cast iron
daily, and consumes 1-1/3 cwt. of coke for each cwt. of cast iron
produced; being 7 tons of coke _per diem_.

The consumption of the three flue fires is 30 pounds of small coal, for
100 pounds of cast-iron produced, which may be reckoned equivalent to 15
pounds of coke; hence altogether each ton of cast iron requires for its
production 1-1/2 tons of coke.

The same furnace worked with the cold blast, the same pressure and the
same ores, produced only 3-1/2 tons of cast iron daily, with an
expenditure of 2·55 of coke for 1 of cast iron; in which case the coke
amounted to 9 tons daily.

The returns by the hot blast compared with those by the cold, are
therefore as the numbers 3 and 2, which shows an advantage by the former
plan of 50 per cent. The consumption of fuel in the two cases is as 8 to
9, being a saving in this article of about 11 per cent. Coke is used on
account of sulphur in the coal.

_Hot-blast heated by the flame of the furnace mouth._--This system is
mounted in Staffordshire. The heating apparatus is there set immediately
upon the mouth of the furnace; and is composed of 2 large cast-iron
cylinders of the same length, the one within the other, leaving a space
between them. This annular interval amounts to 16 inches, and it is
closed at top and bottom: but the innermost cylinder is open at both
ends, and forms, indeed, the vent of the chimney or furnace. It carries
nine rows of pipes, three in each row, which cross its interior, and
open into the annular space.

The flame of the furnace passes between the intervals of the cross
pipes, heating them, and also the two upright cylinders with which they
are connected. The air of the blowing machine arrives by a vertical
pipe, which is placed at the back of the furnace; it enters into the
above annular space, and thence circulates, with more or less velocity,
through the 27 cross tubes, upon which the flame is continually playing;
lastly, it is drawn through to the bottom of the annular space; the two
tubes which conduct it to the two tuyères, pass down within the
brickwork of the furnace, and thus prevent the dissipation of its heat.

Below this heating apparatus there is a door for putting the charges
into the furnace.

The above arrangement does not seem to be the best for obtaining the
greatest possible heat for the blast, nor for favouring the free action
of the furnace; but it illustrates perfectly well the principle of this
application. A serpentine movement in a long bent hot channel would be
much better adapted for communicating heat to so bad a conductor as air
is known to be.

In the month of July, 1836, I paid a visit to Codner Park and Butterly
works, in Derbyshire, belonging to the eminent iron-masters, Messrs.
Jessop and Co., where I was kindly permitted not only to study the
various processes of the manufacture of cast and wrought iron, but to
inspect the registers of the products of cast iron in their blast
furnaces for several years back. It appeared that in the year 1829, only
29 tons of cast iron were made weekly in each of the blast furnaces at
Codner Park. They were then worked with coke, and blown with cold air.
Each ton of iron required for its production, at that time, 6·82 tons of
coals, made into coke for smelting; with 2·64 of roasted iron ore
(carbonate), called mine; and 0·87 of limestone, the _castine_ of the
French.

In 1835 and 1836, the same furnaces turned out weekly, 49 tons of cast
iron each; and every ton of iron required for its production only 3 tons
of coal (not made into coke); 2·72 tons of mine; and 0·77 of lime.

In 1829, and for many years before, as well as one or two after, each
ton of coals is said to have cost for coking the sum of 6_s._, whence
the 6·82 tons of coals then converted into coke for smelting one ton of
iron, cost fully 40_s._ in coking alone, in addition to their prime
cost. The saving in this respect, therefore, is 40_s._ upon each ton of
iron, besides the saving of fully half the coal, and the increased
produce of nearly 60 per cent. of metal per week. The iron-master pays
the patentee 1_s._ upon every ton of iron which he makes, and at the
prices of 1836, he lessened his expenses by, at least, 30_s._ or 40_s._
per ton by the patent improvement.

The following tabular view of the progression in the management and
results of the hot blast, is given by M. Dufrénoy, after visiting the
various iron works in this country where it had been introduced.

“At the Clyde iron works, near Glasgow; in 1829, when the combustion was
effected by the cold air blast,--

                                                             Coal.
                                                       Tons. cwt.   lbs.
  There were consumed, for smelting; 3 tons of coke,
                       equivalent to                     6    13      0
        ----           for the blowing engine            1     0      7
                                                         --------------
                       Total coal per ton of iron        7    13      7
                       Limestone                         0    10-1/2  0

  In 1831, with the hot blast at 450° F., coke being
  still used in smelting,--

  There were consumed, for smelting; 1 ton 18 cwt. of
                       coke, equivalent to               4     6      0
        ----           for heating the air, 5 cwt.   }
        ----           for the blowing engine, 7 cwt.}   0    12      4
                       4 lbs.                        }
                                                         --------------
                       Total coal per ton of iron        4    18      4
                       Limestone                         0     9      0

  In July, 1833, with the hot blast at 612° F., raw
  coal alone being used for smelting,--
  There were consumed, for smelting                      2     0      0
        ----           for heating the air               0     8      0
        ----           for the blowing engine            0    11      2
                                                         --------------
                       Total coal per ton of iron        2    19      2
                       Limestone                         0     7      0

“At the last period the use of hot air had increased the make of the
furnaces by more than one third, and had consequently produced a great
saving of expense in the article of labour. The quantity of blast
necessary for the furnaces was also sensibly diminished; for a blowing
engine of seventy-horse power, which, in 1829, served only for three
blast furnaces, was now sufficient for the supply of four.

“On comparing these several results, we find that the economy of fuel is
in proportion to the temperature to which the air is raised. As for the
actual saving, it varies in every work, according to the nature of the
coal, and the care with which the operation is conducted.

“This process, though it has been four years in use in the works near
Glasgow, (which it has rescued from certain ruin) has scarcely passed
the borders of Scotland; the marvellous advantages, however, which it
has produced, are beginning to triumph over prejudice, and gradually to
extend its use into the different English iron districts. There are
one-and-twenty works, containing altogether sixty-seven blast furnaces,
in which hot air is used. The pig iron run out of these furnaces is
generally No. 1., and is fit for making the most delicate castings. This
process is equally applicable to forge pigs for the manufacture of bar
iron; since in order to obtain this quality of iron, it is only
necessary to alter the proportion of fuel and mineral. In the forges of
the Tyne iron-works, near Newcastle, and of Codner Park, near Derby,
pigs made in furnaces blown by hot air, are alone used in the
manufacture of bar iron.

“In the side of the tuyère pipe a small hole is made, by means of which
the heat of the air may be ascertained at any moment. This precaution is
indispensable, it being of importance to the beneficial use of hot air,
that it be kept at a uniformly high temperature. With a proper apparatus
the air is raised to 612 degrees Fahr., which is a greater heat, by
several degrees, than is necessary for the fusion of lead.”

“At Calder works the consumption of fuel has diminished in the
proportion of 7 tons 17 cwt. to 2 tons 2 cwt. There has also been a
great diminution of expense in limestone, of which only 5-1/2 cwt. are
now used, instead of 13 cwt., which were used in 1828. This decrease
results, as I have already said, from the high temperature which the
furnace has acquired since the introduction of hot air.

“The quantity of blast has been reduced from 3500 cubic feet per minute,
to 2627 cubic feet; the pressure also has been reduced from 3-1/4 to
2-3/4 lbs.”

_Of the refinery of cast iron, or its conversion into bar-iron, in
England._--This operation is naturally divisible into three distinct
parts. The first, or the finery properly speaking, is executed in
peculiar furnaces called _running out fires_; the second operation
completes the first, and is called _puddling_; and the third consists in
welding several iron bars together, and working them under forge
hammers, and between rolls.

1. The _finery furnaces_ are composed of a body of brickwork, about 9
feet square; rising but little above the surface of the ground. The
hearth, placed in the middle, is two feet and a half deep; it is
rectangular, being in general, 3 feet by 2, with its greatest side
parallel to the face of the tuyères; and it is made of cast iron in four
plates. On the side of the tuyères there is a single brick wall. On the
three other sides, sheet iron doors are placed, to prevent the external
air from cooling the metal, which is almost always worked under an open
shed, or in the open air, but never in a space surrounded by walls. The
chimney, from 15 to 18 feet high, is supported upon four columns of cast
iron; its lintel is four feet above the level of the hearth, in order
that the labourers may work without restraint.

The number of tuyères is from two to three; they are placed at the
height of the lip of the crucible or hearth, and distributed so as to
divide its length into equal parts; their axes being inclined towards
the bottom, at an angle of from 25° to 30°, so as to point upon the bath
of melted metal as it flows. The cast-iron nose-pipe is encased, and
water is made to circulate in the hollow space by means of cylindrical
tubes; being introduced by one tube, and let off by another, so as to
prevent the tuyères from getting burned in the process.

Two nozzles are usually placed in each tuyère, to render the blast
constant and uniform; and for the same end, the air impelled by the
bellows, is sometimes received at first in a regulator. The quantity of
air blown into the fineries is considerable; being nearly 400 cubic feet
per minute for each finery; or about the eighth part of the consumption
of a blast furnace.

[Illustration: 590 591]

The finery furnace, or running out fire, is represented in _figs._ 590.
and 591. It is a smelting hearth, in which by first fusing and then
cooling gray cast iron in a peculiar way, it is converted into white
cast iron, called fine iron, or fine metal, of the quality of forge pig,
for making malleable iron by the puddling process. The furnace resembles
the forge hearth employed in Germany and France for converting forge pig
into wrought iron; but it differs, particularly in this, that the fused
iron is run out into an oblong iron trough, for sudden congelation.

_a_ is the air-chest, in communication with the blowing cylinder, or
bellows; the air being conducted through at least two blast pipes to
the fire, and sometimes through even 4 or 6 pipes. _b_ is the side of
the furnace, corresponding to the tuyère plates, in which are the
openings for the blast pipes. All the sides of the furnace are hollow,
and are kept cool by the circulation of water through the cavity between
them. _c_ is the front wall of the furnace, having a strong cast-iron
plate containing the tap holes for running off the melted metal. _d d_
is the exterior wall of the furnace, which corresponds to the
_contre-vent_ and ash-hearth of the French refining forge. _e_, is the
top plate upon which the coke is piled up in store. _f f_, _f f_, iron
props of the chimney, (not shown in this view). _g_, cast-iron trough
into which the fine iron is run off in fusion; which is sometimes made
in one piece, but more usually in separate plates joined together.
Beneath this mould a stream of water is made to flow. _h_ is the bottom
of the hearth, covered with sand.

In the finery process, the hearth or crucible of the furnace is filled
with coke; then six pigs of cast iron are laid horizontally on the
hearth, namely, four of them parallel to the four sides, and two in the
middle above; and the whole is covered up in a dome-form, with a heap of
coke. The fire is now lighted, and in a quarter of an hour the blast is
applied. The cast iron flows down gradually, and collects in the
crucible; more coke being added as the first quantity burns away. This
operation proceeds by itself; the melted metal is not stirred about, as
in some modes of refinery, and the temperature is always kept high
enough to preserve the metal liquid. During this stage the coals are
observed continually heaving up, a movement due in part to the action of
the blast, and in part to an expansion caused in the metal by the
discharge of gaseous oxide of carbon. When all the pig iron is collected
at the bottom of the hearth, which happens commonly at the end of two
hours, or two and a half, the tap hole is opened, and the _fine_ metal
flows out with the slag, into the loam-coated pit, on a plate 10 feet
long, 3 broad, and from 2 inches to 2-1/2 thick. A portion of the slag
forms a small crust on the surface of the metal; but most part of it
collects in a basin scooped out at the bottom of the pit, into which the
fine metal is run.

A large quantity of water is thrown on the fine metal, with the view of
rendering it brittle, and perhaps of partially oxidizing it. This metal
suddenly cooled, is very white, and possesses in general a fibrous
radiated texture; or sometimes a cellular, including a considerable
number of small spherical cavities, like a decomposed amygdaloid rock.
If the cast iron be of bad quality, a little limestone is occasionally
used in the above operation.

Three samples of cinder, analyzed by Berthier, gave,

  Silica 0·276; protox. of iron, 0·612; alumina, 0·040;
                                             phosp. acid, 0·072, Dudley.
   ----  0·368       ----        0·610   ----    0·015;
                                                    puddling of Dowlais.
   ----  0·424       ----        0·520   ----    0·033;
                                                                  ditto.

The remarkable fact of the presence of phosphoric acid, shows how
important this operation is to the purification of the iron. The charge
varies from a ton and a quarter to a ton and a half of pigs; and the
loss by the process varies from 12 to 17 per cent.

The _fine metal_ is broken into fragments, and sent to the puddling
furnace after the product of each operation has been weighed. The coal
consumed in the fine metal process is from 4 to 5 hundred weight for the
ton of cast iron. About 10 tons may be refined _per diem_, a quantity
somewhat greater than the supply from a blast furnace; but the fineries
are not worked on the Sundays; and therefore a smelting furnace just
keeps one of them in play. Whatever care be taken in this process, the
bar iron finally resulting is never so good as if wood charcoal had been
used in the refinery; and hence in making sheet iron for the tin plate
manufacture, wood charcoal is substituted for coke in one Welsh
establishment. The cast iron treated with charcoal, gets into clots or
lumps in the finery furnace, which are lifted out, set under the hammer,
and flattened into thin cakes.

The main effect of the finery process, is probably the separation of the
plumbaginous part of the charcoal, which is disseminated through the
gray cast iron in a state of imperfect chemical combination. When that
is removed the metal becomes more homogeneous, having no crystalline
carbon present to counteract its transition into pure iron; much of the
silica and manganese are also vitrified together, and run off in the
finery cinder.

[Illustration: 592]

2. The _puddling furnace_, is of the reverberatory form. It is bound
generally with iron, as represented in the side view, _fig._ 592., by
means of horizontal and vertical bars, which are joined together and
fixed by wedges, to prevent them from starting asunder. Very frequently,
indeed, the reverberatory furnaces are armed with cast-iron plates over
their whole surface. These are retained by upright bars of cast iron
applied to the side walls, and by horizontal bars of iron, placed across
the arch or roof. The furnace itself is divided interiorly into three
parts; the _fire-place_, the _hearth_, and _flue_. The _fire-place_
varies from 3-1/2 to 4-1/2 feet long, by from 2 feet 8 inches to 3 feet
4 inches wide. The door way by which the coke is charged, is 8 inches
square, and is bevelled off towards the outside of the furnace. This
opening consists entirely of cast iron, and has a quantity of coal
gathered round it. The bars of the fire grate are movable, to admit of
more readily clearing them from ashes.

[Illustration: 593 594]

_Fig._ 593. is a longitudinal section referring to the elevation, _fig._
592., and _fig._ 594. is a ground plan. When the furnace is a single
one, a square hole is left in the side of the fire-place opposite to the
door, through which the rakes are introduced, in order to be heated.

[Illustration: 595]

_a_ is the fire door; _b_, the grate; _c_, the fire bridge; _d d_,
cast-iron hearth plates, resting upon cast-iron beams _e e_, which are
bolted upon both sides to the cast-iron binding plates of the furnace.
_f_ is the hearth covered with cinders or sand; _g_, is the main working
door, which may be opened and shut by means of a lever _g´_, and chain
to move it up and down. In this large door there is a hole 5 inches
square, through which the iron may be worked with the paddles or rakes;
it may also be closed air-tight. There is a second working door _h_,
near the flue, for introducing the cast iron, so that it may soften
slowly, till it be ready for drawing towards the bridge. _i_, is the
chimney, from 30 to 50 feet high, which receives commonly the flues of
two furnaces, each provided with a damper plate or _register_. _Fig._
595., shows the main damper for the top of the common chimney, which may
be opened or shut to any degree by means of the lever and chain. _k_,
_fig._ 593., is the tap or floss hole far running off the slag or
cinder.

The sole is sometimes made of bricks, sometimes of cast iron. In the
first case it is composed of fire-bricks set on edge, forming a species
of flat vault. It rests immediately on a body of brickwork either solid
or arched below. When it is made of cast iron, which is now beginning to
be the general practice, it may be made either of one piece or of
several. It is commonly in a single piece, which, however, causes the
inconvenience of reconstructing the furnace entirely when the sole is to
be changed. In this case it is a little hollow, as is shown in the
preceding vertical section; but if it consists of several pieces, it is
usually made flat.

The hearths of cast iron rest upon cast-iron pillars, to the number of
four or five; which are supported on pedestals of cast iron placed on
large blocks of stone. Such an arrangement is shown in the figure, where
also the square hole _a_, _fig._ 592., for heating the rake irons, may
be observed. The length of the hearth is usually six feet; and its
breadth varies from one part to another. Its greatest breadth, which is
opposite the door, is four feet. In the furnace, whose horizontal plan
is given above, and which produces good results, the sole exhibits, in
this part, a species of ear, which enters into the mouth of the door. At
its origin towards the fireplace, it is 2 feet 10 inches wide; from the
fire it is separated, moreover, by a low wall of bricks (the
fire-bridge) 10 inches thick, and from 3 inches to 5 high. At the other
extremity its breadth is 2 feet. The curvature presented by the sides of
the sole or hearth is not symmetrical; for sometimes it makes an
advancement, as is observable in the plan. At the extremity of the sole
furthest from the fire, there is a low rising in the bricks of 2-1/2
inches, called the altar, for preventing the metal from running out at
the _floss-hole_ when it begins to fuse. Beyond this shelf the sole
terminates in an inclined plane, which leads to the _floss_, or outlet
of the slag from the furnace. This _floss_ is a little below the level
of the sole, and is hollowed out of the basement of the chimney. The
slag is prevented from concreting here, by the flame being made to pass
over it, in its way to the sunk entry of the chimney; and there is also
a plate of cast iron near this opening, on which a moderate fire is kept
up to preserve the fluidity of the scoriæ, and to burn the gases that
escape from the furnace, as also to quicken the draught, and to keep the
remote end of the furnace warm. On the top of this iron plate, and at
the bottom of the inclined plane, the cinder accumulates in a small
cavity, whence it afterwards flows away; whenever it tends to congeal,
the workman must clear it out with his rake.

The door is a cast-iron frame filled up inside with fire-bricks; through
a small hole in its bottom the workmen can observe the state of the
furnace. This hole is at other times shut with a stopper. The chimney
has an area of from 14 to 16 inches.

The hearth stands 3 feet above the ground. Its arched roof, only one
brick thick, is raised 2 feet above the fire-bridge, and above the level
of the sole, taken at the middle of the furnace. At its extreme point
near the chimney, its elevation is only 8 inches; and the same height is
given to the opening of the chimney.

In most iron-works the sole is covered with a layer of refractory sand,
from 2-1/2 to 3 inches thick, which is lightly beat down with a shovel.
At each operation a portion of the sand is carried away; and is replaced
before another. Within these few years, there has been substituted for
the sand a body of pounded slags; a substitution which has occasioned,
it is said, a great economy of iron and fuel.

The fine metal obtained by the coke is _puddled_ by a continuous
operation, which calls for much care and skill on the part of the
workmen. To charge the puddling furnace, pieces of _fine metal_ are
successively introduced with a shovel, and laid one over another on the
sides of the hearth, in the form of piles rising to the roof; the middle
being left open for puddling the metal, as it is successively fused.
Indeed, the whole are kept as far separate as possible, to give free
circulation to the air round the piles. The working door of the furnace
is now closed, fuel is laid on the grate, and the mouth of the
fire-place as well as the side opening of the grate, are both filled up
with coal, at the same time that the damper is entirely opened.

The fine metal in about twenty minutes comes to a white-red heat, and
its thin-edged fragments begin to melt and fall in drops on the sole of
the furnace. At this period the workman opens the small hole of the
furnace door, detaches with a rake the pieces of fine metal that begin
to melt, tries to expose new surfaces to the action of the heat, and in
order to prevent the metal from running together as it softens, he
removes it from the vicinity of the fire-bridge. When the whole of the
fine metal has thus got reduced to a pasty condition, he must lower the
temperature of the furnace, to prevent it from becoming more fluid. He
closes the damper, takes out a portion of the fire, and the ribs of the
grate, and also throws a little water sometimes on the semi-fused mass.
He then works about with his paddle the clotty metal, which swells up,
with the discharge of gaseous oxide of carbon, burning with a blue
flame, as if the bath were on fire. The metal becomes finer by degrees,
and less fusible; or in the language of the workmen, it begins to get
_dry_. The disengagement of the oxide of carbon diminishes, and soon
stops. The workmen continue meanwhile to puddle the metal till the whole
charge be reduced to the state of incoherent sand; and at that time, the
ribs of the grate are replaced, the fire is restored, and the register
is progressively opened up. With the return of the heat, the particles
of metal begin to agglutinate, the charge becomes more difficult to
raise, or in the labourers’ language, it _works heavy_. The refining is
now finished, and nothing remains but to gather the iron into balls. The
founder with his paddle takes now a little lump of metal, as a nucleus,
and makes it roll about on the surface of the furnace, so as to collect
more metal, and form a ball of about 60 or 70 pounds weight. With a kind
of rake, called in England a _dolly_, and which he heats beforehand, the
workman sets this ball on that side of the furnace most exposed to the
action of the heat, in order to unite its different particles; which he
then squeezes together to force out the scoriæ. When all the balls are
fashioned, (they take about 20 minutes work,) the small opening of the
working door is closed with a brick, to cause the heat to rise, and to
facilitate the welding. Each ball is then lifted out, either with tongs,
if roughing rollers are to be used as in Wales, or with an iron rod
welded to the lump as a handle, if the hammer is to be employed, as in
Staffordshire. Thus we see that the operation lasts in whole from 2
hours to 2-1/2; in a quarter of an hour, the fine metal melts at its
edges, when the puddling begins, in order to effect its division; at the
end of an hour or an hour and a half, the metal is entirely reduced to a
sand; a state that is kept up for half an hour by continual stirring;
and finally, the balling operation takes nearly the same time.

The charge for each operation is from 3-1/2 to 4 hundred weight; and
sometimes the cuttings of bar-ends are introduced, which are puddled
apart. The loss of iron is here very variable, according to the degree
of skill in the workman, who by negligence may suffer a considerable
body of iron to scorify or to flow into the hearth and raise the bottom.
In good working, the loss is from 8 to 10 per cent. In Wales, the
consumption of coal is estimated at one ton for every ton of fine metal.
About five puddling furnaces are required for the service of one
smelting furnace and one finery. The hearth of the puddling furnace
should be exposed to heat for 12 hours before the work begins on the
Mondays; and on the Saturdays, the old sole must be cleared out, by
melting it off; and running it out by the floss-hole.

Mr. Schafthault obtained, in May, 1835, a patent for the conversion of
cast into wrought iron, by adding a mixture of black oxide of manganese,
common salt and potter’s clay, in certain small portions, successively
to the melting iron in the puddling furnace.

_The reheating furnaces_, _balling furnaces_, or mill furnaces, are
analogous to the puddling furnaces, but only of larger dimensions.

The wood charcoal forge hearth is employed for working up scrap iron
into boiler plate, &c. Here 22 bushels of charcoal are consumed in
making one ton of iron of that description, from boiler plate parings.

_Machines for forging and condensing the iron._--In England there are
employed for the forging and drawing out of the iron, cast-iron hammers
of great weight, and cylinders of different dimensions, for beating out
the balls, or extending the iron into bars, as also powerful shears.
These several mechanisms are moved either by a steam engine, as in
Staffordshire, and in almost all the other counties of England, or by
water-wheels when the localities are favourable, as in many
establishments in South Wales. We shall here offer some details
concerning these machines.

The main driving shaft usually carries at either end a large toothed
wheel, which communicates motion to the different machines through
smaller toothed wheels. Of these, there are commonly six, four of which
drive four different systems of cylinders, and the two others work the
hammer and the shears. The different cylinders of an iron work should
never be placed on the same arbor, because they are not to move
together, and they must have different velocities, according to their
diameter. In order to economise time and facilitate labour, care is
taken to associate on one side of the motive machine the hammer, the
shears, and the reducing cylinders; and on the other side, to place the
several systems of cylinders for drawing out the iron into bars. For the
same reason the puddling furnaces ought to be grouped on the side of the
hammer; and the reheating furnaces on the other side of the works.

[Illustration: 596]

The hammers, _fig._ 596., are made entirely of cast iron; they are
nearly 10 feet long, and consist usually of two parts, the helve _c_,
and the head or pane _d_. The latter enters with friction into the
former, and is retained in its place by wedges of iron or wood. The head
consists of several faces or planes receding from each other; for the
purpose of giving different forms to the ball lumps. A ring of cast-iron
_a_, called the _cam-ring bag_, bearing movable cams _b b_, drives the
hammer _d_, by lifting it up round its fulcrum _f_, and then letting it
fall alternately. In one iron work, this ring was found to be 3 feet in
diameter, 18 inches thick, and to weigh 4 tons. The weight of the helve
(handle) of the corresponding hammer was 3 tons and a half, and that of
the head of the hammer, 8 hundred weight.

The anvil _e_ consists also of two parts; the one called the pane of the
anvil, is the counterpart of the pane of the hammer; it likewise weighs
8 hundred weight. The second _g_, named the stock of the anvil, weighs 4
tons. Its form is a parallelopiped, with the edges rounded. The _bloom_,
or rough ball, from the puddle furnace, is laid and turned about upon
it, by means of a rod of iron welded to each of them, called a _porter_.
Since the weight of these pieces is very great, and the shocks very
considerable, the utmost precautions should be taken in setting the
hammer and its anvil upon a substantial mass of masonry, as shown in the
figure, over which is laid a double, or even quadruple flooring of wood,
formed of beams placed in transverse layers close to each other. Such
beams possess an elastic force, and thereby partially destroy the
injurious reaction of the shock. In some works, a six-feet cube of cast
iron is placed as a pedestal to the anvil.

Forge hammers are very frequently mounted as levers of the first kind,
with the centre of motion about one-third or one-fourth of the length of
the helve from the cam wheel. The principle of this construction will be
understood by inspection of _fig._ 605. The short end of the lever which
is struck down by the tappet _c_, is driven against the end of an
elastic beam _a_, and immediately rebounds, causing the long end to
strike a harder blow upon the anvil _s_.

The shears are composed of two branches, the one fixed and the other
movable, each formed of two pieces. The fixed branch is a cast-iron
plate, which forms one mass with a horizontal base fixed to a piece of
wood or cast iron buried in the ground. A sharpened chisel is fastened
to its upper part by screws and nuts. The movable branch is likewise of
cast iron; it bears an axis round which it turns, and this axis passes
through the fixed part. It is also furnished with a cutting chisel,
fixed on by nuts and screws. An excentric or an ellipse, moved directly
by a toothed wheel, lifts the movable branch of the shears, and forces
it to cut the iron bars presented to it. The pressure exerted by these
scissors is such, that they can cut without difficulty, iron bars,
one-half or two-thirds of an inch thick.

_Cylinders._--The compression between cylinders now effects, in a few
seconds, that condensation and distribution of the fibres, which 40
years ago, could not be accomplished till after many heats in the
furnace, and many blows of the hammer. The cylinders may be
distinguished into two kinds; 1. those which serve to draw out the ball,
called _puddling rolls_, or roughing rolls, and which are, in fact,
reducing cylinders; 2. the cylinders of extension, called _rollers_, for
drawing into bars the massive iron after it has received a welding, to
make it more malleable. This second kind of cylinders is subdivided
into several varieties, according to the patterns of bar iron that are
required. These may vary from 2 inches square to less than one-sixth of
an inch.

Beneath the cylinders there is usually formed an oblong fosse, into
which the scoriæ and the scales fall when the iron is compressed. The
sides of this fosse, constructed of stone, are founded on a body of
solid masonry, capable of supporting the enormous load of the cylinders.
Beams of wood form in some measure the sides of this pit, to which
cylinders may be made fast, by securing them with screws and bolts.
Massive bars of cast iron are found, however, to answer still better,
not only because the uprights and bearers may be more solidly fixed to
them, but because the basement of heavy metal is more difficult to
shatter or displace, an accident which happens frequently to the wooden
beams. A rill of water is supplied by a pipe to each pair of cylinders,
to hinder them from getting hot; as also to prevent the hot iron from
adhering to the cylinder, by cooling its surface, and perhaps producing
on it a slight degree of oxidizement.

The shafts are one foot in diameter for the hammer and the roughing
rolls; and six inches where they communicate motion to the cylinders
destined to draw the iron into bars.

The _roughing rolls_ are employed either to work out the lump or ball
immediately after it leaves the puddling furnace, as in the Welsh
forges, or only to draw out the piece, after it has been shaped under
the hammer, as is practised in most of the Staffordshire establishments.
These roughing cylinders are generally 7 feet long, including the
trunnions, or 5 feet between the bearers, and 18 inches diameter; and
weigh in the whole from 4 to 4-1/2 tons. They contain from 5 to 7
grooves, commonly of an elliptical form, one smaller than another in
regular progression, as is seen in _fig._ 597. The small axis of each
ellipse, as formed by the union of the upper and under grooves, is
always placed in the vertical direction, and is equal to the great axis,
or horizontal axis of the succeeding groove; so that in transferring the
bar from one groove to another, it must receive a quarter of a
revolution, whereby the iron gets elongated in every direction.
Sometimes the roughing rolls serve as preparatory cylinders, in which
case they bear towards one extremity rectangular grooves, as the figure
exhibits. Several of these large grooves are bestudded with small
asperities analogous to the teeth of files, for biting the lump of iron,
and preventing its sliding. On a level with the under side of the
grooves of the lower cylinder, there is a plate of cast iron with
notches in its edge adapted to the grooves. This piece called the apron,
rests on iron rods, and serves to support the balls and bars exposed to
the action of the rollers, and to receive the fragments of ill-welded
metal, which fall off during the drawing. The _housing frames_ in which
the rollers are supported and revolve, are made of great strength. Their
height is 5 feet; their thickness is 1 foot in the side perpendicular to
the axis of the cylinders, and 10 inches in the other. Each pair of
bearers is connected at their upper ends by two iron rods, on which the
workmen rest their tongs or pinchers for passing the lump or bar from
one side of the cylinders to the other.

The cods or bushes are each composed of two pieces; the one of hard
brass, which presents a cylindrical notch, is framed into the other
which is made of cast iron, as is clearly seen in _fig._ 597.

The iron bar delivered from the square grooves, is cut by the shears
into short lengths, which are collected in a bundle in order to be
welded together. When this bundle of bars has become hot enough in the
furnace, it is conveyed to the rollers; which differ in their
arrangement according as they are meant to draw iron from a large or
small piece. The first, _fig._ 597., possess both elliptical and
rectangular grooves; are 1 foot in diameter and 3 feet long between the
bearers. The bar is not finished under these cylinders, but is
transferred to another pair, whose grooves have the dimensions proper
for the bar, with a round, triangular, rectangular, or fillet form. The
triangular grooves made use of for square iron, have for their profile,
an isosceles triangle slightly obtuse, so that the space left by the two
grooves together may be a rhombus, differing little from a square, and
whose smaller diagonal is vertical. When the bar is to be passed
successively through several grooves of this kind, the larger or
horizontal diagonal of each following groove is made equal to the
smaller or upright of the preceding one, whereby the iron must be turned
one fourth round at each successive draught, and thus receive pressure
in opposite directions. Indeed the bar is often turned in succession
through the triangular and rectangular grooves, that its fibres may be
more accurately worked together. The decrement in the capacity of the
grooves follows the proportion of 15 to 11.

When it is intended to reduce the iron to a small rod, the cylinders
have such a diameter, that three may be set in the same housing frame.
The lower and middle cylinders are employed as roughing rollers, while
the upper and middle ones are made to draw out the rod. When a rod or
bar is to be drawn with a channel or gutter in its face, the grooves of
the rollers are suitably formed.

[Illustration: 598]

To draw out square rods of a very small size, as nail-rods, a system of
small rollers is employed, called _slitters_. Their ridges are
sharp-edged, and enter into the opposite grooves 2-1/2 inches deep; so
that the flat bar in passing between such rollers is instantaneously
divided into several slips. For this purpose the rollers represented in
_fig._ 598. may be put on and removed from the shaft at pleasure.

The velocity of the cylinders varies with their dimensions. In one work,
cylinders for drawing out iron of from one-third to two-thirds of an
inch thick, make 140 revolutions per minute; while those for iron of
from two-thirds of an inch to 3 inches, make only 65. In another work,
the cylinders for two inch iron, make 95 revolutions per minute; those
for iron from two-thirds of an inch to an inch and a third, make 128;
and those for bars from one-third to two-thirds of an inch, 150. The
_roughing rollers_ move with only one-third the velocity of the drawing
cylinders.

The shingling and plate-rolling mill is represented in _fig._ 597. The
shingling mill, for converting the blooms from the balling furnace into
bars, consists of two sets of grooved cylinders, the first being called
_puddling rolls_ or _roughing rolls_; the second are for reducing or
drawing the iron into mill-bars, and are called simply _rolls_.

[Illustration: 597]

_a_, _a_, _a_, _a_, are the powerful uprights or standards called
_housing frames_, of cast iron, in which the gudgeons of the rolls are
set to revolve; _b_, _b_, _b_, _b_, are bolt rods for binding these
frames together at top and bottom; _c_, are the roughing rolls, having
each a series of triangular grooves, such that between those of the
upper and under cylinder, rectangular concavities are formed in the
circumference with slightly sloping sides. The end groove to the right
of _c_, should be channelled like a rough file, in order to take the
better hold of the blooms, or to bite the metal as the workmen say; and
give it the preparatory elongation for entering into and passing through
the remaining grooves till it comes to the square ones, where it becomes
a mill-bar. _d_, _d_, are the smooth cylinders, hardened upon the
surface, or _chilled_ as it is called, by being cast in iron moulds, for
rolling iron into plates or hoops. _e_, _e_, _e_, _e_, are strong screws
with rectangular threads, which work by means of a wrench or key, into
the nuts _e´ e´ e´ e´_, fixed in the standards; they serve to regulate
the height of the plummer blocks or bearers of the gudgeons, and thereby
the distance between the upper and under cylinders. _f_ is a junction
shaft; _g_, _g_, _g_, are solid coupling boxes, which embrace the two
separate ends of the shafts, and make them turn together. _h_, _h_, are
junction pinions, whereby motion is communicated from the driving shaft
_f_, through the under pinion to the upper one, and thus to both upper
and under rolls at once. _i_, _i_, are the pinion standards in which
their shafts run; they are smaller than the uprights of the rolls. _k_,
_k_, are screws for fastening the head pieces _l_ to the top of the
pinion standards. All the standards are provided with sole plates _m_,
whereby they are screwed to the foundation beams, _n_, of wood or
preferably iron, as shown by dotted lines; _o o_ are the binding screw
bolts. Each pair of rolls at work is kept cool by a small stream of
water let down upon it from a pipe and stop-cock.

In the cylinder drawing, the workman who holds the ball in tongs, passes
it into the first of the elliptical grooves; and a second workman on the
other side of the cylinders, receives this lump, and hands it over to
the first, who re-passes it between the rollers, after bringing them
somewhat closer to each other, by giving a turn to the adjusting
pressure screws. After the lump has passed five or six times through the
same groove, it has got an elliptical form, and is called in England a
_bloom_. It is next passed through a second groove of less size, which
stretches the iron bar. In this state it is subjected to a second pair
of cylinders, by which the iron is drawn into flat bars, 4 inches broad
and half an inch thick. Fragments of the ball or bloom fall round about
the cylinders; which are afterwards added to the puddling charge. In a
minute and a half, the rude lump is transformed into bars, with a
neatness and rapidity which the inexperienced eye can hardly follow. A
steam engine of thirty-horse power can _rough down_ in a week, 200 tons
of coarse iron.

This iron called mill-bar iron, is however of too inferior a quality to
be employed in any machinery; and it is subjected to another operation,
which consists in welding several pieces together, and working them into
a mass of the desired quality. The iron bars while still hot, are cut by
the shears into a length proportional to the size of iron bar that is
wanted; and four rows of these are usually laid over each other into a
heap or pile, which is placed in the _re-heating_ furnace above
described, and exposed to a free circulation of heat; one pile being set
crosswise over another. In a half or three quarters of an hour, the iron
is hot enough, and the pieces now sticking together, are carried in
successive piles to the bar-drawing cylinders, to be converted into
strong bars, which are reckoned of middle quality. When a very tough
iron is wanted, as for anchors, another welding and rolling must be
given. In the re-heating ovens, the loss is from 8 to 10 per cent. on
the large bar iron, and from 10 to 12 in smaller work. A ton of iron
consumes in this process, about 150 lbs. of coals.

It is thought by many that a purer iron is obtained by subjecting the
balls as they come out of the puddling furnace, to the action of the
hammer at first, than to the roughing rollers; and that by the latter
process vitrified specks remain in the metal, which the hammer expels.
Hence, in some works, the balls are first worked under the forge-hammer;
and these _stampings_ being afterwards heated in the form of pies or
cakes piled over each other, are passed through the roughing rollers.

Having given ample details concerning the manufacturing processes used
in England for making cast iron, it may be proper to subjoin a few
observations upon its chemical constitution. It has been generally
believed and taught that the dark gray cast iron, No. 1. or No. 2.,
contains more carbon than the white cast iron; and that the superior
quality of the former in tenacity and softness, is to be ascribed to
that excess. But the distinguished German metallurgist, M. Karsten, in
his instructive volume, “Handbuch der Eisenhüttenkunde,” or manual of
the art of smelting iron ores, has proved, on the contrary, that the
white cast iron contains most charcoal; that this substance exists in it
in a state of combination with the whole body of the iron; that the
foliated or lamellar white cast iron contains as much carbon as iron can
absorb in the liquid state; and that this constitutes a compound of 4
atoms of iron combined with 1 of charcoal, or 112 + 6; or 5-1/3 per
cent.; whereas the dark gray cast iron contains generally from 3 to 4
per cent., in the state of plumbago merely dispersed through the metal.
He has further confirmed his opinion, by causing the white variety to
pass into the gray, and reciprocally. Thus, dark gray cast metal melted
and suddenly cooled, gives a silvery white metal, hard and brittle. On
the other hand, when the white cast iron is cooled very slowly after
fusion, the condition of the carbon in it changes, and a dark gray cast
iron is obtained. These phenomena shew that the graphite or plumbago,
which requires a high temperature for its formation, cannot be produced
but by a slow cooling, which allows the carbon to agglomerate itself in
the iron in the state of graphite; while under a rapid congelation, the
carbon remains dissolved in the mass, and produces a white metal. Hence
we may understand how each successive fusion of dark gray iron hardens
and whitens it, though in contact with coke, by completing that chemical
dissolution of the carbon on which the white state depends.

In the manufacture of the blackest No. 1. cast iron, it sometimes
happens that a considerable quantity of a glistening carburet of iron
appears, floating on the top of the metal as it is run out into the
sand-moulds. This substance is called _kish_ by the English workmen; and
it affords a sure test of the good state of the furnace and quality of
the iron.

The most remarkable fact relative to the smelting of cast iron, is the
difference of product between the workings of the summer and the winter
season, though all the materials and machinery be the same. In fact, no
cold-blast furnace will carry so great a burden in summer as in winter,
that is, afford so great a product of metal, or bear so great a charge
of ore with the same quantity of coke. This difference is undoubtedly
due to the dilated and humid state of the atmosphere in the warm season.
A very competent judge of this matter, states the diminution in summer
at from one-fifth to one-seventh, independently of deterioration of
quality.

Some of the foreign irons, particularly certain Swedish and Russian
bars, are imported into Great Britain in large quantities, and at prices
much greater than those of the English bars, and therefore the modes of
manufacturing such excellent metal deserve examination. All the best
English cast steel, indeed, is made from the hoop L, iron from
Dannemora, in Sweden.

The processes pursued in the smelting works of the Continent have
frequently in view to obtain from the ore malleable iron directly, in a
pure or nearly pure state. The furnaces used for this purpose are of two
kinds, called in French, 1. _Feux de Loupes_, or _Forges Catalanes_; and
2. _Fourneaux à pièce_, or _Forges Allemandes_.

[Illustration: 599]

[Illustration: 600]

In the Catalan, or French method, the ore previously roasted in a kiln
is afterwards strongly torrefied in the forge before the smelting
begins; operations which follow in immediate succession. Ores treated in
this way should be very fusible and very rich; such as black oxide of
iron, hematites, and certain spathose iron ores. From 100 parts of ore,
50 of metallic iron have been procured, but the average product is 35.
The furnaces employed are rectangular hearths, _figs._ 599. and 600.,
the water-blowing machine being employed to give the blast. See
METALLURGY. There are three varieties of this forge; the Catalan, the
Navarrese, and the Biscayan. The dimensions of the first, the one most
generally employed, are as follows: 21 inches long, in the direction _p
f_, _fig._ 600.; 18-1/2 broad, at the bottom of the hearth or _creuset_,
in the line A B; and 17 inches deep, _fig._ 599. The tuyère, _q p_, is
placed 9-1/2 inches above the bottom, so that its axis is directed
towards the opposite side, about 2 inches above the bottom. But it must
be movable, as its inclination needs to be changed, according to the
stage of the operation, or the quantity of the ores. It is often raised
or lowered with pellets of clay; and even with a graduated circle, for
the workmen make a great mystery of this matter. The hearth is lined
with a layer of _brasque_ (loam and charcoal dust worked together), and
the ore after being roasted is sifted; the small powder being set aside
to be used in the course of the operation. The ore is piled up on the
side opposite to the blast in a sharp saddle ridge, and it occupies
one-third of the furnace. In the remaining space of two-thirds, the
charcoal is put. To solidify the small ore on the hearth, it is covered
with moist cinders mixed with clay.

The fire is urged with moderation during the first two hours, the
workman being continually employed in pressing down more charcoal as the
former supply burns away, so as to keep the space full, and prevent the
ore from crumbling down. By a blast so tempered at the beginning, the
ore gets well calcined, and partially reduced in the way of cementation.
But after two hours, the full force of the air is given; at which period
the fusion ought to commence. It is easy to see whether the torrefaction
be sufficiently advanced, by the aspect of the flame, as well as of the
ore, which becomes spongy or cavernous; and the workman now completes
the fusion, by detaching the pieces of ore from the bottom, and placing
them in front of the tuyère. When the fine siftings are afterwards
thrown upon the top, they must be watered, to prevent their being blown
away, and to keep them evenly spread over the whole surface of the light
fuel. They increase the quantity of the products, and give a proper
fusibility to the scoriæ. When the scoriæ are viscid, the quantity of
siftings must be diminished; but if thin, they must be increased. The
excess of slag is allowed to run off by the _chio_ or floss hole. The
process lasts from five to six hours, after which the pasty mass is
taken out, and placed under a hammer to be cut into lumps, which are
afterwards forged into bars.

Each mass presents a mixed variety of iron and steel; in proportions
which may be modified at pleasure; for by using much of the siftings,
and making the tuyère dip towards the sole of the hearth, iron is the
chief product; but if the operation be conducted slowly, with a small
quantity of siftings, and an upraised tuyère, the quantity of steel is
more considerable. This primitive process is favourably spoken of by M.
Brongniart. The weight of the lump of metal varies from 200 to 400
pounds. As the consumption of charcoal is very great, amounting in the
Palatinate or Rheinkreis to seven times the weight of iron obtained,
though in the Pyrenees it is only thrice, the Catalan forge can be
profitably employed only where wood is exceedingly cheap and abundant.

The _Fourneaux à pièce_ of the French, or _Stuck-ofen_ of the Germans,
resembles _fig._ 313., (COPPER); the tuyère (not shown there) having a
dip towards the bottom of the hearth, where the smelted matter collects.
When the operation is finished, that is at least once in every 24 hours,
one of the sides of the hearth must be demolished, to take out the pasty
mass of iron, more or less pure. This furnace holds a middle place in
the treatment of iron, between the Catalan forge and the cast-iron
_floss-ofen_, or high-blast furnaces. The _stuck-ofen_ are from 10 to 15
feet high, and about 3 feet in diameter at the hearth. Most usually
there is only one aperture for the tuyère and for working; with a small
one for the escape of the slag; on which account, the bellows are
removed to make way for the lifting out of the lump of metal, which is
done through an opening left on a level with the sole, temporarily
closed with bricks and potters’ clay, while the furnace is in action.

This outlet being closed, and the furnace filled with charcoal, fire is
kindled at the bottom. Whenever the whole is in combustion, the roasted
ore is introduced at the top in alternate charges with charcoal, till
the proper quantity has been introduced. The ore falls down; and
whenever it comes opposite to the tuyère the slag begins to flow, and
the iron drops down and collects at the bottom of the hearth into the
mass or _stuck_; and in proportion as this mass increases, the
_floss-hole_ for the slag and the tuyère is raised higher. When the
quantity of iron accumulated in the hearth is judged to be sufficient,
the bellows are stopped, the scoriæ are raked off, the little brick wall
is taken down, and the mass of iron is removed by rakes and tongs. This
mass is then flattened under the hammer, into a cake from 3 to 4 inches
thick, and is cut into two lumps, which are submitted to a new
operation; where it is treated in a peculiar refinery, lined with
charcoal _brasque_, and exposed to a nearly horizontal blast. The above
mass seized in the jaws of powerful tongs, is heated before the tuyère;
a portion of the metal flows down to the bottom of the hearth, loses its
carbon in a bath of rich slags or fused oxides, and forms thereby a mass
of iron thoroughly refined. The portion that remains in the tongs
furnishes steel, which is drawn out into bars.

This process is employed in Carniola for smelting a granular oxide of
iron. The mass or _stuck_ amounts to from 15 to 20 hundred weight, after
each operation of 24 hours. Eight strong men are required to lift it
out, and to carry it under a large hammer, where it is cut into pieces
of about 1 cwt. each. These are afterwards refined, and drawn into bars
as above described. These furnaces are now almost generally abandoned on
the Continent, in favour of _charcoal high or blast furnaces_.

_Fig._ 313. represents a _schachtofen_, (but without the tuyère, which
may be supposed to be in the usual place), and is, like all the
continental _Hauts Fourneaux_, remarkable for the excessive thickness of
its masonry. The charge is put in at the throat, near the summit of the
octagonal or square concavity, for they are made of both forms. At the
bottom of the hearth there is a dam-stone with its plate, for permitting
the overflow of the slag, while it confines the subjacent fluid metal;
as well as a tymp-stone with its plate, which forms the key to the front
of the hearth; the boshes are a wide funnel, almost flat, to obstruct
the easy descent of the charges, whereby the smelting with charcoal
would proceed too rapidly. The bottom of the hearth is constructed of
two large stones, and the hinder part of one great stone, called in
German _rückstein_ (back stone), which the French have corrupted into
_rustine_. In other countries of the Continent, the boshes are
frequently a good deal more tapered downwards, and the hearth is larger
than here represented. The refractory nature of the Hartz iron ores is
the reason assigned for this peculiarity.

In Sweden there are blast-furnaces, _schachtofen_, 35 feet in height,
measured from the boshes above the line of the hearth, or _creuset_.
Their cavity has the form of an elongated ellipse, whose small diameter
is 8 feet across, at a height of 14 feet above the bottom of the hearth;
hence, at this part, the interior space constitutes a belly
corresponding with the upper part of the boshes. In other respects the
details of the construction of the Swedish furnaces resemble the one
figured above. Marcher relates that a furnace of that kind whose height
was only 30 feet, in which brown hydrate of iron (_hematite_) was
smelted, yielded 47 _per cent._ in cast iron, at the rate of 5 hundred
weight a day, or 36 hundred weight one week after another; and that in
the production of 100 pounds of cast iron, 130 pounds of charcoal were
consumed. That furnace was worked with forge bellows, mounted with
leather.

The decarburation of cast iron is merely a restoration of the carbon to
the surface, in tracing inversely the same progressive steps as had
carried it into the interior during the smelting of the ore. The oxygen
of the air, acting first at the surface of the cast metal, upon the
carbon which it finds there, burns it: fresh charcoal, oozing from the
interior, comes then to occupy the place of what had been dissipated;
till, finally, the whole carbon is transferred from the centre to the
surface, and is there converted into either carbonic acid gas or oxide
of carbon; for no direct experiment has hitherto proved which of these
is the precise product of this combustion.

This diffusibility of carbon through the whole mass of iron constitutes
a movement by means of which cast iron may be refined even without
undergoing fusion, as is proved by a multitude of phenomena. Every
workman has observed that steel loses a portion of its steely properties
every time it is heated in contact with air.

On the above principle, cast iron may be refined at one operation. Three
kinds of iron are susceptible of this continuous process:--1. The
speckled cast-iron, which contains such a proportion of oxygen and
carbon as with the oxygen of the air and the carbon of the fuel may
produce sufficient and complete saturation, but nothing in excess. 2.
The dark gray cast-iron. 3. The white cast-iron. The nature of the crude
metal requires variations both in the form of the furnaces, and in the
manipulations.

Indeed malleable iron may be obtained directly from the ores by one
fusion. This mode of working is practised in the Pyrenees to a
considerable extent. All the ores of iron are not adapted for this
operation. Those in which the metallic oxide is mixed with much earthy
matter, do not answer well; but those composed of the pure black oxide,
red oxide, and carbonate, succeed much better. To extract the metal from
such ores, it is sufficient to expose them to a high temperature, in
contact either with charcoal, or with carbonaceous gases; the metallic
oxide is speedily reduced. But when several earths are present, these
tend continually, during the vitrification which they suffer, to retain
in their vitreous mass the unreduced oxide of iron. Were such earthy
ores, as our ironstones, to be put into the low furnaces called
_Catalan_, through which the charges pass with great rapidity, and in
which the contact with the fuel is merely momentary, there would be
found in the crucible or hearth merely a rich metallic glass, instead of
a lump of metal.

In smelting and refining by a continuous operation, three different
stages may be distinguished:--1. The roasting of the ore to expel the
sulphur, which would be less easily separated afterwards. The roasting
dissipates likewise the water, the carbonic acid, and any other volatile
substances which the minerals may contain. 2. The deoxidizement and
reduction to metal by exposure to charcoal or carburetted vapours. 3.
The melting, agglutination, and refining of the metal to fit it for the
heavy hammers where it gets nerve. There are several forges in which
these three operations seem to be confounded into a single one, because,
although still successive, they are practised at one single heating
without interruption. In other forges, the processes are performed
separately, or an interval elapses between each stage of the work. Three
systems of this kind are known to exist:--1. The Corsican method; 2. The
Catalan with wood charcoal; and 3. The Catalan with coke.

The furnaces of Corsica are a kind of semicircular basins, 18 inches in
diameter, and 6 inches deep. These are excavated in an area, or a small
elevation of masonry, 8 or 10 feet long by 5 or 6 broad, and covered in
with a chimney. This area is quite similar to that of the ordinary
hearths of our blast-furnaces.

The tuyère stands 5 or 6 inches above the basin, and has a slight
inclination downwards. In Corsica, and the whole portion of Italy
adjoining the Mediterranean shores, the iron ore is an oxide similar to
the specular ore of the Isle of Elba. This ore contains a little water,
some carbonic acid, occasionally pyrites, but in small quantity. Before
deoxidizing the ore, it is requisite to expel the water and carbonic
acid combined with the oxide, as well as the sulphur of the pyrites.

The operations of roasting, reduction, fusion, and agglutination are
executed in the same furnace. These are indeed divided into two stages,
but the one is a continuation of the other. In the first, the two
primary operations are performed at once;--the reduction of a portion of
the roasted ore is begun at the same time that a portion of the raw ore
is roasted: these two substances are afterwards separated. In the second
stage, the deoxidizement of the metal is continued, which had begun in
the preceding stage; it is then melted and agglutinated, so as to form a
ball to be submitted to the forge-hammer.

The roasted pieces are broken down to the size of nuts, to make the
reduction of the metal easier. In executing the first step, the basin
and area of the furnace must be lined with a _brasque_ of charcoal dust,
3, 4, or even 5 inches thick: over this _brasque_ a mound is raised with
lumps of charcoal, very hard, and 4 or 5 inches high. A semi-circle is
formed round the tuyère, the inner radius of which is 5 or 6 inches.
This mass of charcoal is next surrounded with another pile of the
roasted and broken ores, which must be covered with charcoal dust. The
whole is sustained with large blocks of the raw ore, which form
externally a third wall.

These three piles of charcoal, with roasted and unroasted ore, are
raised in three successive beds, each 7 inches thick: they are separated
from each other by a layer of charcoal dust of about an inch, which
makes the whole 24 inches high. This is afterwards covered over with a
thick coat of pounded charcoal.

The blocks of raw ore which compose the outward wall form a slope; the
larger and stronger pieces are at the bottom, and the smaller in the
upper part. The large blocks are sunk very firmly into the charcoal
dust, to enable them better to resist the pressure from within.

On the bottom of the semicircular well formed within the charcoal lumps,
kindled pieces are thrown, and over these, pieces of black charcoal;
after which the blast of a water-blowing machine (_trompe_) is given.
The fire is kept up by constantly throwing charcoal into the central
well. At the beginning of the operation it is thrust down with wooden
rods, lest it should affect the building; but when the heat becomes too
intense for the workmen to come so near the hearth, a long iron rake is
employed for the purpose. At the end of about 3 hours, the two processes
of roasting and reduction are commonly finished: then the raw ore no
longer exhales any fumes, and the roasted ore, being softened, unites
into lumps more or less coherent.

The workman now removes the blocks of roasted ore which form the outer
casing, rolls them to the spot where they are to be broken into small
pieces, and pulls down the _brasque_ (small charcoal) which surrounds
the mass of reduced ore.

The second operation is executed by cleaning the basin, removing the
slags, covering the basin anew with 2 or 3 brasques, (coats of pounded
charcoal), and piling up to the right and the left, two heaps of
charcoal dust. Into the interval between these conical piles two or
three baskets of charcoal are cast, and on its top some cakes of the
reduced crude metal being laid, the blast is resumed. The cakes, as they
heat, undergo a sort of liquation, or sweating, by the action of the
earthy glasses on the unreduced black oxide present. Very fusible slags
flow down through the mass; and the iron, reduced and melted, passes
finally through the coals, and falls into the slag basin below. To the
first parcel of cakes, others are added in succession. In proportion as
the slags proceeding from these run down, and the melted iron falls to
the bottom, the thin slag is run off by an upper overflow or _chio_
hole, and the reduced iron kept by the heat in the pasty condition,
remains in the basin: all its parts get agglutinated, forming a soft
mass, which is removed by means of a hooked pole in order to be forged.
Each lump or _bloom_ of malleable iron requires 3 hours and a half for
its production.

The iron obtained by this process is in general soft, very malleable,
and but little steely. In Corsica four workmen are employed at one
forge. The produce of their labour is only about 4 cwt. of iron from 10
cwt. of ore and 20 of charcoal, mingled with wood of beech and chestnut.
Though their ore contains on an average 65 per cent. of iron, only about
40 parts are extracted; evincing a prodigious waste, which remains in
the slags.

The difference between the Corsican and the Catalonian methods consists
in the latter roasting the ore at a distinct operation, and employing a
second one in the reduction, agglutination, and refining of the metal.
In the Catalonian forges, 100 pounds of iron are obtained from 300
pounds of ore and 310 pounds of charcoal; being a produce of only 33 per
cent. It may be concluded that there is a notable loss, since the sparry
iron ores, which are those principally smelted, contain on an average
from 54 to 56 per cent. of iron. The same ores smelted in the ordinary
blast furnace produce about 45 per cent. of cast iron.

On the Continent, iron is frequently refined from the cast metal of the
blast furnaces by three operations, in three different ways. In one, the
pig being melted, with aspersion of water, a cake is obtained, which is
again melted in order to form a second cake. This being treated in the
refinery fire, is then worked into a _bloom_. In another system, the pig
iron is melted and cast into plates: these are melted anew in order to
obtain crude balls, which are finally worked into blooms. In a third
mode of manufacture, the pig-iron is melted and cast into plates, which
are roasted, and then strongly heated, to form a bloom.

The French fusible ores, such as the silicates of iron, are very apt to
smelt into white cast iron. An excess of fluxes, light charcoals, too
strong a blast, produce the same results. A surcharge of ores which
deranges the furnace and affords impure slags mixed with much iron, too
rapid a slope in the boshes, too low a degree of heat, and too great
condensation of the materials in the upper part of the furnace; all tend
also to produce a white cast iron. In its state of perfection, white
cast iron has a silver colour, and a bright metallic lustre. It is
employed frequently in Germany for the manufacture of steel, and is then
called _steel floss_, or _lamellar floss_, a title which it still
retains, though it be hardly silver white, and have ceased to be
foliated. When its colour takes a bluish-gray tinge, and its fracture
appears striated or splintery, or when it exhibits gray spots, it is
then styled _flower floss_. In a third species of white cast iron we
observe still much lustre, but its colour verges upon gray, and its
texture is variable. Its fracture has been sometimes compared to that of
a broken cheese. This variety occurs very frequently. It is a white cast
iron, made by a surcharge of ore in the furnace. If the white colour
becomes less clear and turns bluish, if its fracture be contorted, and
contains a great many empty spaces or air-cells, the metal takes the
name of _cavernous-floss_, or _tender-floss_. The whitest metal cannot
be employed for casting. When the white is mixed with the gray cast
iron, it becomes _riband_ or _trout_ cast iron.

[Illustration: 601]

[Illustration: 602]

_The German refining forge._--_Figs._ 601, 602. represent one of the
numerous refinery furnaces so common in the Hartz. The example is taken
from the _Mandelholz_ works, in the neighbourhood of Elbingerode. _Fig._
602. is an elevation of this forge. D is the refinery hearth, provided
with two pairs of bellows. _Fig._ 601. is a vertical section, showing
particularly the construction of the crucible or hearth in the refinery
forge D. C is an overshot water-wheel, which gives an alternate
impulsion to the two bellows _a b_ by means of the revolving shaft _c_,
and the cams or tappets _d f e g_.

D, the hearth, is lined with cast-iron plates. Through the pipe _l_,
cold water may be introduced, under the bottom plate _m_, in order to
keep down, when necessary, the temperature of the crucible, and
facilitate the solidification of the _loupe_ or bloom. An orifice _n_,
_figs._ 601, 602., called the _chio_ (floss hole), allows the melted
slag or cinder to flow off from the surface of the melted metal. The
copper pipe or nose piece _p_, _fig._ 600., conducts the blast of both
bellows into the hearth, as shown at _b x_, _fig._ 602., and D _g p_
_fig._ 600.

The substance subjected to this mode of refinery, is a gray carbonaceous
cast iron, from the works of Rothehütte. The hearth D, being filled and
heaped over with live charcoal, upon the side opposite to the tuyère
_x_, _figs._ 601, 602, long pigs of cast iron are laid with their ends
sloping downwards, and are drawn forwards successively into the hearth
by a hooked poker, so that the extremity of each may be plunged into the
middle of the fire, at a distance of 6 or 8 inches from the mouth of the
tuyère. The workman proceeds in this way, till he has melted enough of
metal to form a _loupe_. The cast iron, on melting, falls down in drops
to the bottom of the hearth; being covered by the fused slags, or
vitreous matters more or less loaded with oxide of iron. After running
them off by the orifice _n_, he then works the cast iron by powerful
stirring with an iron rake (_ringard_), till it is converted into a mass
of a pasty consistence.

During this operation, a portion of the carbon contained in the cast
iron combines with the atmospherical oxygen supplied by the bellows, and
passes off in the form of carbonic oxide and carbonic acid. When the
lump is coagulated sufficiently, the workman turns it over in the
hearth, then increases the heat so as to melt it afresh, meanwhile
exposing it all round to the blast, in order to consume the remainder of
the carbon, that is, till the iron has become ductile, or refined. If
one fusion should prove inadequate to this effect, two are given. Before
the conclusion, the workman runs off a second stratum of vitreous slag,
but at a higher level, so that some of it may remain upon the metal.

The weight of such a _loupe_ or _bloom_ is about 2 cwts., being the
product of 2 cwts. and 7/10 of pig iron; the loss of weight is therefore
about 26 per cent. 149 pounds of charcoal are consumed for every 100
pounds of bar iron obtained. The whole operation lasts about 5 hours.
The bellows are stopped as soon as the bloom is ready; this is
immediately transferred to a forge hammer, such as is represented _fig._
605.; the cast-iron head of which weighs 8 or 9 cwts. The bloom is
greatly condensed thereby, and discharges a considerable quantity of
semi-fluid cinder. The lump is then divided by the hammer and a chisel
into 4 or 6 pieces, which are re-heated, one after another, in the same
refinery fire, in order to be forged into bars, whilst another pig of
cast iron is laid in its place, to prepare for the formation of a new
bloom. The above process is called by the Germans _klump-frischen_, or
lump-refining. It differs from the _durch-brech-frischen_, because in
the latter, the lump is not turned over in mass, but is broken, and
exposed in separate pieces successively to the refining power of the
blast near the tuyère. The French call this _affinage par portions_; it
is much lighter work than the other.

The quality of the iron is tried in various ways; as first, by raising a
bar by one end, with the two hands over one’s head, and bringing it
forcibly down to strike across a narrow anvil at its centre of
percussion, or one-third from the other extremity of the bar; after
which it may be bent backwards and forwards at the place of percussion
several times; 2. a heavy bar may be laid obliquely over props near its
end, and struck strongly with a hammer with a narrow pane, so as to
curve it in opposite directions; or while heated to redness, they may be
kneed backwards and forwards at the same spot, on the edge of the anvil.
This is a severe trial, which the hoop L, Swedish iron, bears
surprisingly, emitting as it is hammered, a phosphoric odour, peculiar
to it and to the bar iron of Ulverstone, which also resembles it, in
furnishing a good steel. The forging of a horseshoe is reckoned a good
criterion of the quality of iron. Its freedom from flaws is detected by
the above modes; and its linear strength may be determined by suspending
a scale to the lower end of a hard-drawn wire, of a given size, and
adding weights till the wire breaks. The treatises of Barlow and
Tredgold may be consulted with advantage on the methods of proving the
strength of different kinds of iron, in a great variety of
circumstances.

Steel of cementation, or blistered steel and cast steel, are treated
under the article STEEL. But since in the conversion of cast iron into
wrought iron, by a very slight difference in the manipulations, a
species of steel may be produced called _natural steel_, I shall
describe this process here.

[Illustration: 603]

_Fig._ 603. is a view of the celebrated steel iron works, called
Königshütte (_king’s-forge_), in Upper Silesia, being one of the best
arranged in Germany, for smelting iron ore by means of coke. The front
shown here is about 400 English feet long. _a a_ are two blast furnaces.
A third blast furnace, all like the English, is situated to the left of
one of the towers _b_. _b b_ are the charging towers, into which the ore
is raised by machinery from the level of the store-houses _l l_, up to
the mouth of the furnaces _a a_; _c c_ point to the positions of the
boilers of the two steam engines, which drive two cylinder bellows at
_f_. _n n n n_ are arched cellars placed below the store-houses _l l_,
for containing materials and tools necessary for the establishment.

[Illustration: 604]

_Figs._ 599., 604., are vertical sections of the forge of Königshütte,
for making natural steel; _fig._ 599. being drawn in the line A B of the
plan, _fig._ 600. _a_ is the bottom of the hearth, consisting of a
fire-proof gritstone; _b_ is a space filled with small charcoal, damped
with water, under which, at _n_, in _fig._ 604., is a bed of well rammed
clay; _d_ is a plate of cast iron, which lines the side of the hearth
called rückstein (backstone) in German, and corrupted by the French into
_rustine_; _f_ is the plate of the counter-blast; _g_ the plate of the
side of the tuyère: behind, upon the face _d_, the fire-place or hearth
is only 5-1/2 inches deep; in front as well as upon the lateral faces,
it is 18 inches deep. By means of a mound made of dry charcoal, the
posterior face _d_, is raised to the height of the face _f_. _i_, _fig._
600., is the floss-hole, by which the slags are run off from the hearth
during the working, and through which, by removing some bricks, the lump
of steel is taken out when finished.

_k l m_ are pieces of cast iron, for confining the fire in front, that
is towards the side where the workman stands; _o_ is the level of the
floor of the works; _p_ a copper tuyère; it is situated 4-1/2 inches
above the bottom _a_, slopes 5 degrees towards it, and advances 4 inches
into the hearth or fire-place, where it presents an orifice, one half
inch in horizontal length, and one inch up and down; _q_ the nose pipes
of two bellows, like those represented in _fig._ 602., and under
SILVER; the round orifice of each of them within the tuyère being one
inch in diameter. _r_ is the lintel or top arch of the tuyère, beneath
which is seen the cross section of the pig of cast iron under operation.

For the production of natural steel, a white cast iron is preferred,
which contains little carbon, which does not flow thin, and which being
cemented _over or above the wind_, falls down at once through the blast
to the bottom of the hearth in the state of steel. With this view, a
very flat fire is used; and should the metal run too fluid, some
malleable lumps are introduced to give the mass a thicker pasty
consistence.

If the natural steel be supposed to contain too little carbon, which is
a very rare case, the metal bath covered with its cinder slag, is
diligently stirred with a wooden pole, or it may receive a little of the
more highly carburetted iron. If it contains the right dose of carbon,
the earthy and other foreign matters are made progressively to sweat
out, into the supernatant slag. When the mass is found by the trial of a
sample to be completely converted, and has acquired the requisite
stiffness, it is lifted out of the furnace, by the opening in front,
subjected to the forge hammer, and drawn into bars. In Sweden, the
cast-iron pigs are heated to a cherry-red, and in this state broken to
pieces under the hammer, before they are exposed in the steel furnace.
These natural steels are much employed on the Continent in making
agricultural implements, on account of their cheapness. The natural
steel of Styria is regarded as a very good article.

Wootz is a natural steel prepared from a black ore of iron in Hindostan,
by a process analogous to that of the Catalan hearth, but still simpler.
It seems to contain a minute portion of the combustible bases of alumina
and silica, to which its peculiar hardness when tempered, may possibly
be ascribed. It is remarkable for the property of assuming a damask
surface, by the action of dilute sulphuric acid, after it has been
forged and polished. See DAMASCUS and STEEL.

[Illustration: 605]

_Fig._ 605. is the German forge-hammer; to the left of 1, is the axis of
the rotatory cam, 2, 3, consisting of 8 sides, each formed of a strong
broad bar of cast iron, which are joined together to make the octagon
wheel. 4, 5, 6, are cast-iron binding rings or hoops; made fast by
wooden wedges. _b_, _b_, are standards of the frame work _e_, _l_, _m_,
in which the helve of the forge hammer has its fulcrum near _u_. _h_,
the sole part of the frame. Another cast-iron base or sole is seen at
_m_. _n_ is a strong stay, to strengthen the frame-work. At _r_ two
parallel hammers are placed, with cast-iron heads and wooden helves. _s_
is the anvil, a very massive piece of cast iron. _t_ is the end of a
vibrating beam, for throwing back the hammer from it forcibly by recoil.
_x y_ is the outline of the water-wheel which drives the whole. The cams
or tappets are shown mounted upon the wheel 6, _g_, 6.

_Analysis of Irons._--Oxidized substances cannot exist in metallic iron,
and the foreign substances it does contain are present in such small
quantities, that it is somewhat difficult to determine their amount. The
most intricate point is, the proportion of carbon. The free carbon,
which is present only in gray cast iron, may, indeed, be determined
nearly, for most of it remains after solution of the metal in acids. The
combined charcoal, however, changes by the action of muriatic acid into
gas and oil; sulphuric acid also occasions a great loss of carbon, and
nitric acid dissipates it almost entirely. Either nitre or chloride of
silver may be employed to ascertain the amount of carbon; but when the
iron contains chromium and much phosphorus, the determination of the
carbon is attended with many difficulties.

The quantity of sulphur is always so small, that it can scarcely be
ascertained by the weight of the precipitate of sulphate of barytes from
the solution of the iron in nitro-muriatic acid. The iron should be
dissolved in muriatic acid; and the hydrogen, as it escapes charged with
the sulphur, should be passed through an acidulous solution of acetate
of lead. The weight of the precipitated sulphuret shows the amount of
sulphur, allowing 13·45 of the latter for 100 of the former. In this
experiment the metal should be slowly acted upon by the acid. Cast iron
takes from 10 to 15 days to dissolve, steel from 8 to 10, and malleable
iron 4 days. The residuum of a black colour does not contain a trace of
sulphur.

Phosphorus and chromium are determined in the following way. The iron
must be dissolved in nitro-muriatic acid, to oxygenate those two bodies.
The solution must be evaporated cautiously to dryness in porcelain
capsules, and the saline residuum heated to redness. A little chloride
of iron is volatilized, and the remainder resembles the red-brown oxide.
This must be mixed with thrice its weight of carbonate of potash, and
fused in a platinum crucible; the quantity of iron being from 40 to 50
grains at most.

The mixture after being acted upon by boiling water, is to be left to
settle, to allow the oxide to be deposited, for it is so fine as to pass
through a filter. If the iron contained manganese, this would be found
_at first_ in the alkaline solution; but manganese spontaneously
separates by exposure to the air. The alkaline liquor must be
supersaturated with muriatic acid, and evaporated to dryness. The liquor
acidulated, and deprived of its silica by filtration, is to be
supersaturated with ammonia; when the alumina will precipitate in the
state of a subphosphate. When the liquor is now supersaturated with
acetic acid, and then treated with acetate of lead, a precipitate of
phosphate of lead almost always falls. There is hardly a bit of iron to
be found which does not contain phosphorus. The slightest trace of
chrome is detected by the yellow colour of the lead precipitate; if this
be white there is none of the colouring metal present.

100 parts of the precipitated phosphate of lead contain, after
calcination, 19·4 parts of phosphoric acid. The precipitate should be
previously washed with acetic acid, and then with water. These 19·4
parts contain 8·525 parts of phosphorus.

Cast iron sometimes contains calcium and barium, which may be detected
by their well-known reagents, oxalate of ammonia, and sulphuric acid. In
malleable iron they are seldom or never present.

The charcoal found in the residuum of the nitro-muriatic solution is to
be burned away under a muffle. The solution itself contains along with
the oxide of iron, protoxide of manganese, and other oxides, as well as
the earths, and the phosphoric and arsenic acids. Tartaric acid is to be
added to it, till no precipitate be formed by supersaturation with
caustic ammonia. The ammoniacal liquor must be treated with
hydrosulphuret of ammonia as long as it is clouded, then thrown upon a
filter. The precipitate is usually very voluminous, and must be well
washed. The liquor which passes through is to be saturated with muriatic
acid, to decompose all the sulphurets.

The solution still contains all the earths and the oxide of titanium,
besides the phosphoric acid. It is to be evaporated to dryness, whereby
the ammonia is expelled, and the carbonaceous residuum must be burned
under a muffle. If the iron contains much phosphorus, the ashes are
strongly agglutinated. They are to be fused as already described along
with carbonate of potash, and the mass is to be treated with boiling
water. The residuum may be examined for silica, lime, barytes, and oxide
of titanium. Muriatic acid being digested on it, then evaporated to
dryness, and the residuum treated with water; will leave the silica.
Caustic ammonia, poured into the solution, will separate the alumina, if
any be present, and the oxide of titanium; but the former almost never
occurs.

Manganese is best sought for by a distinct operation. The iron must be
dissolved at the heat of boiling water, in nitro-muriatic acid; and the
solution, when very cold, is to be treated with small successive doses
of solution of carbonate of ammonia. If the iron has been oxidized to a
maximum, and if the liquor has been sufficiently acid, and diluted with
water, it will retain the whole of the manganese. This process is as
good as that by succinate of ammonia, which requires many precautions.

The liquor is often tinged yellow by carbon, after it has ceased to
contain a single trace of iron oxide. As soon as litmus paper begins to
be blued by carbonate of ammonia, we should stop adding it; immediately
throw the whole upon a filter, and wash continuously with cold water.
What passes through is to be neutralized with muriatic acid, and
concentrated by evaporation. It may contain besides manganese, some
lime, or barytes. It should therefore be precipitated with
hydrosulphuret of ammonia, the hydrosulphuret of manganese should be
collected, dissolved in strong muriatic acid, filtered, and treated, at
a boiling heat, with carbonate of potash. The precipitate, well washed
and calcined, contains, in 100 parts, 72·75 parts of metallic manganese.

The copper, arsenic, lead, tin, bismuth, antimony, or silver, are best
separated by a stream of sulphuretted hydrogen gas passed through the
solution in nitro-muriatic acid, after it is largely diluted with water.
The precipitate must be cautiously roasted in a porcelain test, to burn
away the large quantity of sulphur which is deposited in consequence of
the conversion of the peroxide of iron into the protoxide. If nothing
remains upon the test, none of these metals is present. If a residuum be
obtained, it must be dissolved in nitro-muriatic acid, and subjected to
examination. But, in fact, carbon, sulphur, phosphorus, silicon, and
manganese, are the chief contaminators of iron.

Chloride of silver affords the means of determining the proportion of
carbon contained in iron, and of ascertaining the state in which that
substance exists in the metal. Fused chloride of a pale yellow colour
must be employed. The operation is to be performed in close vessels,
with the addition of a great deal of water, and a few drops of muriatic
acid. The carbonaceous residuum is occasionally slightly acted upon. We
may judge of this circumstance by the gases disengaged, as well as by
the appearance of the charcoal.

Ductile iron and soft steel, as well as white cast-iron which has been
rendered gray by roasting, when decomposed by chloride of silver, afford
a blackish-brown unmagnetic charcoal, and a plumbaginous substance
perfectly similar to what is extracted from the same kinds of iron, by
solution in acids. A portion of this plumbago is also converted into
charcoal of a blackish brown colour, by the action of the chloride.
Hence this agent does not afford the means of obtaining what has been
called the poly-carburet, till it has produced a previous decomposition.
But we obtain it, in this manner, purer and in greater quantity than we
could by dissolving the metal in the acids. The only subject of regret
is, that we possess no good criterion for judging of the progress of
this analytical operation.

Gray cast iron leaves, besides the polycarburet, a residuum of plumbago,
and carbon which was not chemically combined with the iron; while
tempered steel and white cast iron afford merely a blackish brown
charcoal; but the operation is extremely slow with the latter two
bodies, because a layer of charcoal forms upon the surface, which
obstructs their oxidizement. For this reason the white cast iron ought
to be previously changed into gray by fusion in a crucible lined with
charcoal, before being subjected to the chloride of silver; if this
process be employed for tempered steel, the combined carbon becomes
merely a polycarburet. It would not be possible to operate upon more
than 15 grains, which require from 60 to 80 times that quantity of the
chloride, and a period of 15 days for the experiment.

The residuum, which is separable from the silver only by mechanical
means, should be dried a long time at the heat of boiling water. It
contains almost always iron and silica. After its weight is ascertained,
it is to be burned in a crucible of platinum till the ashes no longer
change their colour, and are not attractable by the magnet. The
difference between the weights of the dried and calcined residuum is the
weight of the charcoal. The oxide of iron is afterwards separated from
the silica by muriatic acid.

In operating upon gray cast iron, we should ascertain separately the
proportion of graphite or plumbago, and that of the combined charcoal.
To determine the former, we dissolve a second quantity of the cast iron
in nitric acid, with a little muriatic; the residuum, which is graphite,
is separated from the silica and the combined carbon by the action of
caustic potash. After being washed and dried, it must be weighed. The
weight of the graphite obtained being deducted from the quantity of
carbon resulting from the decomposition effected by the chloride of
silver, the remainder is the amount of the chemically combined carbon.

By employing muriatic acid, we could dissipate at once the combined
carbon; but this method would be inexact, because the hydrogen
disengaged would carry off a portion of the graphite.

According to Karsten, Mushet’s table of the quantities of carbon
contained in different steels and cast irons is altogether erroneous. It
gives no explanation why, with equal proportions of charcoal, cast iron
constitutes at one time a gray, soft, granular metal, and at another, a
white, hard, brittle metal in lamellar facets. The incorrectness of
Mushet’s statement becomes most manifest when we see the white lamellar
cast iron melted in a crucible lined with charcoal, take no increase of
weight, while the gray cast iron treated in the same way becomes
considerably heavier.

Analysis has never detected a trace of carbon _unaltered_ or of graphite
in white cast iron, if it did not proceed from small quantities of the
gray mixed with it; while perfect gray cast iron affords always a much
smaller quantity of carbon altered by combination, and a much greater
quantity of graphite. Neither kind of cast iron, however, betrays the
presence of any oxygen. Steel affords merely altered carbon, without
graphite; the same thing holds true of malleable iron; while the iron
obtained by fusion with 25 per cent. of scales of iron contains no
carbon at all.

The graphite of cast iron is obtained in scales of a metallic aspect,
whereas the combined carbon is obtained in a fine powder. When the white
cast iron has been roasted, and become gray, and is as malleable as the
softest gray cast iron, it still affords no graphite as the latter does,
though in appearance both are alike. Yet in their properties they are
still essentially dissimilar.

With 4-1/4 per cent. of carbon, the white cast iron preserves its
lamellar texture; but with less carbon, it becomes granular and of a
gray colour, growing paler as the dose of carbon is diminished, while
the metal after passing through an indefinite number of gradations,
becomes steely cast iron, very hard steel, soft steel, and steely
wrought iron.

The steels of the forge and the cast steels examined by Karsten,
afforded him from 2·3 to 1-1/4 per cent. of carbon; in the steel of
cementation, (blistered steel) he never found above 1-3/4 of carbon.
Some wrought irons which ought to contain no charcoal, hold as much as
1/2 per cent. and they then approach to steel in nature. The softest and
purest irons contain still 0·2 per cent. of carbon.

The quantity of graphite which gray cast iron contains, varies,
according to Karsten’s experiments, from 2·57 to 3·75 per cent.; but it
contains besides, some carbon in a state of alteration. The total
contents in carbon varied from 3·15 to 4·65 per cent. When the
congelation of melted iron is very slow, the carbon separates, probably
in consequence of its crystallizing force, so as to form a gray cast
iron replete with plumbago. If the gray do not contain more charcoal
than the white from which it has been formed, and if it contain the
charcoal in the state of mechanical mixture, then it can have little or
none in a state of combination, even much less than what some steels
contain. Hence we can account for some of its peculiarities in reference
to white cast iron; such as its granular texture, its moderate hardness,
the length of time it requires to receive annealing colours, the
modifications it experiences by contact of air at elevated temperatures,
the high degree of heat requisite to fuse it, its liquidity, and finally
its tendency to rust by porosity, much faster than the white cast iron.

We thus see that carbon may combine with iron in several manners; that
the gray cast iron is a mixture of steely iron and plumbago; that the
white, rendered gray and soft by roasting, is a compound of steely iron
and a carburet of iron, in which the carbon predominates; and that
untempered steel is in the same predicament.

For the following analyses of cast irons, we are indebted to MM. Gay
Lussac and Wilson.

TABLE.--In 100 parts.

  +----------------------+------+-----+-----+-----+-------+------------+
  |     Cast iron.       |Iron. |Car- |Sili-|Phos-| Man-  |  Remarks.  |
  |                      |      |bon. | ca. |pho- |ganese.|            |
  |                      |      |     |     |rus. |       |            |
  +----------------------+------+-----+-----+-----+-------+------------+
  |White cast from Siegen|94·338|2·690|0·230|0·162|2·590  |By wood     |
  |                      |      |     |     |     |       |  charcoal  |
  |Do.     Coblentz      |94·654|2·441|0·230|0·185|2·490  |    do.     |
  |Do.     a. d. Champ   |96·133|2·324|0·840|0·703|a trace|    do.     |
  |Do.     Isère         |94·687|2·636|0·260|0·280|2·137  |    do.     |
  |Gray    Nivernais     |95·673|2·254|1·030|1·043|a trace|    do.     |
  |Do.     Berry         |95·573|2·319|1·920|0·188|  do   |Mix. of coke|
  |                      |      |     |     |     |       |       & do.|
  |Do.     a. d. Champ   |95·971|2·100|1·060|0·869|  do.  |Charcoal    |
  |Do.     Creusot       |93·385|2·021|3·490|0·604|  do.  |Coke        |
  |Do.     a. d. Franche |      |     |     |     |       |            |
  |            Comté     |95·689|2·800|1·160|0·351|  do.  |    do.     |
  |Do.     Wales         |94·842|1·666|3·000|0·492|  do.  |    do.     |
  |Do.     Do.           |95·310|2·550|1·200|0·440|  do.  |    do.     |
  |Do.     Do.           |95·150|2·450|1·620|0·780|  do.  |    do.     |
  +----------------------+------+-----+-----+-----+-------+------------+

Karsten has given the following results as to carbon, in 100 parts of
gray cast iron.

  +--------------------------------+-----+----+----+----------------+
  |      Gray cast iron.           |Com- |Free|To- |   Remarks.     |
  |                                |bined|car-|tal |                |
  |                                |car- |bon.|car-|                |
  |                                |bon. |    |bon.|                |
  +--------------------------------+-----+----+----+----------------+
  |Siegen, from brown iron-stone   | 0·89|3·71|4·60|By wood charcoal|
  |Siegen (Widderstein), from brown|     |    |    |                |
  |and sparry iron                 | 1·03|3·62|4·65|      do.       |
  |Malapane, from spherosiderite   | 0·75|3·15|3·90|      do.       |
  |Königshütte, from brown ore     | 0·58|2·57|3·15|     coke       |
  |Do. at a lower smelting heat    | 0·95|2·70|3·65|      do.       |
  +--------------------------------+-----+----+----+----------------+

[Illustration: 606 607]

_Fig._ 607. represents in section, and _fig._ 606. in plan, the famous
cupola furnace for casting iron employed at the Royal Foundry in Berlin.
It rests upon a foundation _a_, from 18 to 24 inches high, which
supports the basement plate of cast iron, furnished with ledges, for
binding the lower ends of the upright side plates or cylinder, _e_. Near
the mouth there is a top-plate _d_, made in several pieces, which serves
to bind the sides at their upper end, as also to cover in the walls of
the shaft. These plates are most readily secured in their places by
screws and bolts. Within this iron case, at a little distance from it,
the proper furnace-shaft _e_, is built with fire-bricks, and the space
between this and the iron is filled up with ashes. The sole of the
hearth _f_, over the basement-plate, is composed of a mixture of
fire-clay and quartz-sand firmly beat down to the thickness of 6 or 8
inches, with a slight slope towards the discharge-hole for running off
the metal. _g_ is the _form_ or the tuyère (there are sometimes one on
each side); _h_ the nose pipe; the discharge aperture _i_ is 12 inches
wide and 15 inches high; across which the sole of the hearth is rammed
down. During the melting operation, this opening is filled up with
fire-clay; when it is completed, a small hole merely is pierced through
it at the lowest point, for running off the liquid metal. The hollow
shaft should be somewhat wider at bottom than at top. Its dimensions
vary with the magnitude of the foundry. When 5 feet high, its width at
the level of the tuyère or blast-hole may be from 20 to 22 inches. From
250 to 300 cubic feet of air per minute are required for the working of
such a cupola. For running down 100 pounds of iron, after the furnace
has been brought to its heat, 48 pounds of ordinary coke are used; but
with the hot blast much less will suffice. The furnace requires feeding
with alternate charges of coke and iron every 8 or 10 minutes. The waste
of iron, by oxidization and slag, amounts in most foundries to fully 5
per cent. For carrying off the burnt air, a chimney-hood is commonly
erected over the cupola. See FOUNDRY.

The double-arched air or wind-furnace used in the foundries of
Staffordshire for melting cast iron, has been found advantageous in
saving fuel, and preventing waste by slag. It requires fire-bricks of
great size and the best composition.

The main central key-stone is constructed of large fire-bricks made on
purpose; against that key-stone the two arches press, having their
abutments at the sides against the walls. The highest point of the roof
is only 8 inches above the melted metal. The sole of the hearth is
composed of a layer of sand 8 inches thick, resting upon a bed of iron
or of brickwork. The edge of the fire-bridge is only 3 inches above the
fluid iron.

In from 2 to 4 hours from 1 to 3 tons of metal may be founded in such a
furnace, according to its size; but it ought always to be heated to
whiteness before the iron is introduced. 100 pounds of cast iron require
from 1 to 1-1/2 cubic foot of coal to melt them. The waste varies from 5
to 9 per cent.

I shall conclude the subject of iron with a few miscellaneous
observations and statistical tables. Previously to the discovery by Mr.
Cort, in 1785, of the methods of puddling and rolling or shingling iron,
this country imported 70,000 tons of this metal from Russia and Sweden;
an enormous quantity for the time, if we consider that the cotton and
other automatic manufactures, which now consume so vast a quantity of
iron, were then in their infancy; and that two years ago, the whole of
our importation from these countries did not exceed 40,000 tons. From
the following table of the prices of bar iron in successive years, we
may infer the successive rates of improvement and economy, with slight
vicissitudes.

  +------+-----------------+
  |Years.|    Per Ton.     |
  +------+-----------------+
  |      |_£ s._     _£ s._|
  | 1824 | 9  0  to  10  0 |
  | 1825 |10  0  --  14  0 |
  | 1826 | 8 10  --  10  0 |
  | 1827 | 8  0  --   9  0 |
  | 1828 | 7 10  --   8  0 |
  | 1829 | 5 10  --   7  0 |
  | 1830 | 5  5  --   6  0 |
  | 1831 | 5  5  --   5 10 |
  | 1832 | 5  0  --   5 10 |
  | 1833 | 5 10  --   6  0 |
  | 1834 | 6  0  --   6 10 |
  | 1835 | 5 10  --   7  0 |
  +------+-----------------+

I have been informed upon good authority that the total production of
iron in Great Britain, in the year 1836, was almost exactly ONE MILLION
OF TONS!

The export of iron that year, in bars, rods, pigs, castings, wire,
anchors, hoops, nails, and old iron, amounted to 189,390 tons; in
unwrought steel to 3,014, and in cutlery, to 21,072; in whole to
213,478: leaving apparently for internal consumption 776,522 tons, from
which however one tenth probably should be deducted for waste, in the
conversion of the bar iron. Hence 700,000 tons may be taken as the
approximate quantity of iron made use of in the United Kingdom, in the
year 1836.

The years 1835 and 1836 being those of the railway mania over the world,
produced a considerable temporary rise in the price of bar iron; but as
this increased demand caused the construction of a great many more
smelting and refining furnaces, it has tended eventually to lower the
prices; an effect also to be ascribed to the more general use of the hot
blast.

The relative cost of making cast iron at Merthyr Tydvil in South Wales,
and at Glasgow, was as follows, eight or nine years ago.

                              _At Merthyr._

             _s._        _Tons. Cwts. Qrs._  _£  s. d._
  Raw mine at 10 per ton,  3     7     0      1 13  6
  Coal     at  6           2    16     0      0 16  6
  Limestone                1     5     2      0  1  4
  Other charges                               0  9  1
                                             --------
  Total Cost                                  3  0  5

                              _At Glasgow._

               _s. d._   _Tons. Cwts._       _£  s. d._
  Raw mine at    4  6      3    10            0 16  3
  Splint Coal at 2  5      5    15            0 14  0
  Limestone at   0  3      0    14            0  3  6
  Coals for the engine     1    10            0  3  0
  Other charges                               1  1  0
                                             --------
      Total cost                              2 17  9

The cost is still nearly the same at Merthyr, but it has been greatly
decreased at Glasgow.

The saving of fuel by the hot-blast is said to be in fact so great, that
blowing cylinders, which were adequate merely to work three furnaces at
the first period, were competent to work four furnaces at the last
period. The saving of materials has moreover been accompanied by an
increase of one-fourth in the quantity of iron, in the same time; as a
furnace which turned out only 60 tons a week with the cold blast, now
turns out no less than 80 tons. That the iron so made is no worse, but
probably better, when judiciously smelted, would appear from the
following statement. A considerable order was not long since given to
four iron-work companies in England, to supply pipes to one of the
London water companies. Three of these supplied pipes made from the
cold-blast iron; the fourth, it is said, supplied pipes made with the
hot-blast iron. On subjecting these several sets of pipes to the
requisite trials by hydraulic pressure, the last lot was found to stand
the proof far better than any of the former three.--That iron was made
with raw coal.

I have been since told by eminent iron-masters of Merthyr, that this
statement stands in need of confirmation, or is probably altogether
apocryphal, and that as they find the hot blast weakens the iron, they
will not adopt it.

Between the cast irons made in different parts of Great Britain, there
are characteristic differences. The Staffordshire metal runs remarkably
fluid, and makes fine sharp castings. The Welsh is strong, less fluent,
but produces bar iron of superior quality. The Derbyshire iron also
forms excellent castings, and may be worked with care into very good bar
iron. The Scotch iron is very valuable for casting into hollow wares, as
it affords a beautiful smooth skin from the moulds, so remarkable in the
castings of the Carron company, in Stirlingshire, and of the Phœnix
foundry, at Glasgow. The Shropshire iron resembles the Staffordshire in
its good qualities.

The average quantity of fine metal obtainable from the forge-pigs at
Merthyr Tydvil, from the finery furnace, is one ton for 22-1/2 cwt. of
cast iron, with a consumption of about 9-1/2 cwt. of coal per ton.

_Estimate of the average cost of erecting three blast furnaces._

                      BUILDING EXPENSES.

  Foundations                                                     _£_480
  Masonry of hewn grit-stones                                        600
  Common bricklayers’ work                                          1200
  Lining of the furnace, hearth, &c., in fire-bricks                1140
  Fire-clay for building                                              80
  Lime and sand                                                      800

                          CAST IRON.

  Cast-iron pieces, such as dam-plates, tymp-plates, beams,
  tuyère-plates, &c., weighing about 24 tons for each furnace;--in
  whole                                                             1140

                         WROUGHT IRON.

  For the binding-hoops, keys, &c.; 5 tons for each                  300

                        COST OF LABOUR.

  Bricklayers, masons, and labourers in building                    1080

                       VARIOUS EXPENSES.

  Scaffolding                                                         48
  Tools                                                              160
  Shed in front of each furnace                                      480
  Terracing, cost of ground, &c.                                    2400
                                                                    ----
  Total cost of erecting the furnaces                               9908

                      INCIDENTAL CHARGES.

  Blowing machinery, and steam engine of 80-horse power             6400
  Inclined railway for mounting the charges                          120
  Gallery for charging                                               160
  Steam engine house                                                 400
  Chimneys, boilers, &c.                                             480
  Roasting kilns                                                     480
  Coke kilns                                                         800
  Dwelling-houses for workmen                                        800
                                                                  ------
  Total cost of 3 furnaces complete                            _£_19,548

_Estimate from the Neath-Abbey Works in S. Wales, of the cost of
machines requisite for a forge and shingling-mill, capable of turning
out 120 tons of bar iron per week._

   1. Steam-engine upon Bolton and Watt’s construction; of 40
      inches diameter in the cylinder, and 8-feet stroke; with
      boilers, pipes, grate, bars, fire-doors, &c. &c., complete _£_1600
   2. System of great-geering for transmitting the crank-motion
      of the engine to the mill-work, with fly-wheel, &c.           1090
   3. A system of roughing rolls, with pinions, uprights, and every
      thing else necessary                                           525
   4. Two pairs of finisher-rolls, with all their accessories        525
   5. Two pairs of shear-machines, at 170_l._ apiece                 340
   6. One pair of rolls of 10 inches diameter, for making small bar
      iron, with all their accessories                               230
   7. Forge hammer, including the anvil, the cam-shafts, and all the
      other requisites                                               185
   8. A complete turning lathe                                       200
                                                                  ------
                                                                 _£_4695
   9. To the above must be added, spare cylinders weighing about
      60 tons                                                        960
  10. Duplicate articles for the steam-engine                         ?
  11. 150 tons of cast-iron plates, to cover the floor of the mill   900
  12. Eight tons of cast-iron pieces for a reverberatory furnace      52
  13. Tools of malleable iron; rakes, oars, &c.                       28
  14. Castings for mounting a cupola furnace                          50
  15. Blowing-machine for the cupola                                  80
  16. Pieces of iron for a small forge, with two fires, two bellows,
      two anvils, iron tools faced with steel, and common iron tools,
      &c.                                                            100
  17. Eight tons of cast-iron pieces, and wrought-iron pieces for 14
      puddling furnaces                                              983
  18. Seven tons of cast-iron pieces, and wrought iron for 4 re-
      heating furnaces                                               252
  19. Tools for the puddlers and other workmen                        15
  20. Iron mountings for two cranes, partly made of wood              50
                                                                 -------
  Total cost of machines, and pieces of iron                     _£_8165

  To the above, the cost of the steam engine house is to be added, that
  of another forge hammer, and incidental expenses.

In Staffordshire the following estimate has been given:

  A steam-engine of 60-horse power                                  2016
  Rolls, with the iron work of the furnaces, &c., to make 120 tons
  of bar iron weekly                                                2572
                                                                 -------
                                                                 _£_4588

The Neath-Abbey estimate is greater, but that company has a high
character for making substantial well-finished machinery.

Bar iron made entirely from ore without admixture of cinder, or
vitrified oxide, is always reckoned worth 10_s._ a ton more than the
average iron in the market, which is frequently made by smelting 25 per
cent. of cinder with 75 of ore or _mine_, as it is called.

Importation of iron in bars or unwrought, for home consumption; and
amount of duty, in

         1836.                 1837.           1836.       1837.
  18,978 tons 18 cwt. | 13,470 tons 4 cwt. | _£_28,450  | _£_20,065

_M. Virlet’s Statistical Table of the produce of Iron in Europe._

                           Quintals.
  England (1827)           7,098,000
  France (1834)            2,200,000
  Russia (1834)            1,150,000
  Austria (1829)             850,000
  Sweden (1825)              850,000
  Prussia                    800,000
  The Hartz Mountains        600,000
  Holland and Belgium        600,000
  Elba and Italy             280,000
  Piedmont                   200,000
  Spain                      180,000
  Norway                     150,000
  Denmark                    135,000
  Bavaria                    130,000
  Saxony                      80,000
  Poland                      75,000
  Switzerland                 30,000
  Savoy                       25,000
                          ----------
  Total                   13,433,000 (equal to about 672,000 tons.)

For additional statistics of iron, see PITCOAL, at the end.

_Bronzing of polished iron._--The barrels of fowling-pieces and rifles
are occasionally bronzed and varnished, to relieve the eye of the
sportsman from the glare of a polished metal, and to protect the surface
from rusting. The liquid used for browning the barrels is made by mixing
nitric acid of specific gravity 1·2, with its own weight of spirit of
nitric ether, of alcohol, and tincture of muriate of iron; and adding to
that mixture, a quantity of sulphate of copper equal in weight to the
nitric acid and ethereous spirit taken together. The sulphate must be
dissolved in water before being added; and the whole being diluted with
about 10 times its weight of water, is to be bottled up for use. This
liquid must be applied by friction with a rag to the clear barrel, which
must then be rubbed with a hard brush; processes to be alternated two or
three times. The barrel should be afterwards dipped in boiling water,
rendered feebly alkaline with carbonate of potash or soda, well dried,
burnished, and heated slightly for receiving several coats of
tin-smith’s lacquer, consisting of a solution of shellac in alcohol,
coloured with dragon’s blood.


ISINGLASS, or Fish-glue, called in Latin _ichthyocolla_, is a whitish,
dry, tough, semi-transparent substance, twisted into different shapes,
often in the form of a lyre, and consisting of membranes rolled
together. Good isinglass is unchangeable in the air, has a leathery
aspect, and a mawkish taste nearly insipid; when steeped in cold water
it swells, softens, and separates in membranous laminæ. At the boiling
heat it dissolves in water, and the solution, on cooling, forms a white
jelly, which is semi-transparent, soluble in weak acids, but is
precipitated from them by alkalies. It is gelatine nearly pure; and if
not brittle, like other glue, this depends on its fibrous and elastic
texture. The whitest and finest is preferred in commerce. Isinglass is
prepared from the air-bladders of sturgeons, and especially the great
sturgeon, the _accipenser huso_; which is fished on the shores of the
Caspian sea, and in the rivers flowing into it, for the sake chiefly of
its swim bladder.

The preparation of isinglass in this part of Russia, and particularly at
Astracan, consists in steeping these bladders in water, removing
carefully their external coat, and the blood which often covers them,
putting them in a hempen bag, squeezing them, softening them between the
hands, and twisting them into small cylinders, which are afterwards bent
into the shape of a lyre. They are ready for the market immediately
after being dried in the sun, and whitened with the fumes of burning
sulphur.

In some districts of Moldavia, another process is followed. The skin,
the stomach, the intestines, and the swim bladder of the sturgeon are
cut in small pieces, steeped in cold water, and then gently boiled. The
jelly thus obtained is spread in thin layers to dry, when it assumes the
appearance of parchment. This being softened in a little water, then
rolled into cylinders, or extended into plates, constitutes an inferior
article.

The swim bladder of the cod and many other fishes, also furnishes a
species of isinglass, but it is much more membranous, and less soluble
than that of the sturgeon.

The properties of isinglass are the same as those of gelatine or pure
glue; and its uses are very numerous. It is employed in considerable
quantities to clarify ale, wine, liqueurs, and coffee. As an article of
food to the luxurious in the preparation of creams and jellies, it is in
great request. Four parts of it convert 100 of water into a tremulous
jelly, which is employed to enrich many soups and sauces. It is used
along with gum as a dressing to give lustre to ribbons and other silk
articles. The makers of artificial pearls employ it to fix the _essence
d’Orient_ on the glass globules which form these pearls, and the Turks
set their precious stones or jewellery by means of isinglass dissolved
in alcohol along with gum ammoniac; a combination which is also employed
in this country to join broken pieces of china and glass, under the name
of diamond cement. That setting preserves its transparency after it
solidifies, if it be well made.

It is by covering taffety or thin silk with a coat of isinglass that
court plaster is made. A solution of isinglass coloured with carmine
forms an excellent injection liquor to the anatomist. M. Rochen has made
another pretty application of isinglass. He plunges into a limpid
solution of it, made by means of a water bath, sheets of wire gauze set
in window or lamp frames, which, when cold, have the appearance of
glass, and answer instead of it for shades and other purposes. If one
dip be not sufficient to make a proper transparent plate of isinglass,
several may be given in succession, allowing each film to harden in the
interval between the dips. The outer surface should be varnished to
protect it from damp air. These panes of gelatine are now generally used
for lamps instead of horn, in the maritime arsenals of France.

Isinglass imported for home consumption; and duties paid in

     1835.         1836.        1835.      1836.
  1,814 cwts. | 1,735 cwts. | _£_4,290 | _£_4,125


ISLAND MOSS (_Lichen d’Islande_, Fr.; _Flechte Isl._, Germ.); is a
lichen, the _Cetraria islandica_, which contains a substance soluble in
hot water, but forming a jelly when it cools, styled _lichenine_ by M.
Guerin. Lichenine has a yellowish tint in the dry state, is transparent
in thin plates, insipid, inodorous, and difficult to pulverize. Cold
water makes it swell, but does not dissolve it. It is precipitated in
white flocks by alcohol and ether. Iodine tinges it of a brownish green.
Sulphuric acid converts it into sugar; and the nitric into oxalic acid.
Lichenine is prepared by extracting first of all from the plant a bitter
colouring matter, by digesting 1 pound of it in 16 pounds of cold water
containing 1 ounce of pearl-ash; then draining the lichen, edulcorating
with cold water, and boiling it in 9 pounds of boiling water, till 3
pounds be evaporated. The jelly which forms, upon cooling the filtered
solution, is dark coloured, but, being dried and redissolved in hot
water, it becomes clear and colourless. Lichenine consists of 39·33
carbon, 7·24 hydrogen, and 55·43 oxygen. With potash, lime, oxide of
lead, and tincture of galls, the habitudes of lichenine and starch are
the same. The mucilage of island moss is preferred in Germany to common
paste for dressing the warp of webs in the loom, because it remains
soft, from its hygrometric quality. It is also mixed with the pulp for
sizing paper in the vat.


IVORY (_Ivoire_, Fr.; _Elfenbein_, Germ.); is the osseous matter of the
tusks teeth of the elephant, the hippopotamus, or morse, wild boar,
several species of phocæ, as well as the horn or tooth of the narwhal.
Ivory is a white, fine-grained, dense substance, of considerable
elasticity, in thin plates, and more transparent than paper of equal
thickness. The outside of the tusk is covered by the cortical part,
which is softer and less compact than the interior substance, with the
exception of the brown plate that sometimes lines the interior cavity.
The hardest, toughest, whitest, and most translucent ivory, has the
preference in the market; and the tusks of the sea-horse are considered
to afford the best. In these, a rough glassy enamel covers the cortical
part, of such hardness, as to strike sparks with steel. The horn of the
narwhal is sometimes ten feet long, and consists of an ivory of the
finest description, as hard as that of the elephant, and susceptible of
a better polish; but it is not in general so much esteemed as the
latter.

Ivory has the same constituents as the teeth of animals, three-fourths
being phosphate, with a little carbonate of lime; one-fourth cartilage.
See BONES.

It is extensively employed by miniature painters for their tablets; by
turners, in making numberless useful and ornamental objects; by cutlers,
for the handles of knives and forks; by comb-makers; as also by
philosophical instrument makers, for constructing the scales of
thermometers, &c. The ivory of the sea-horse is preferred by dentists
for making artificial teeth; that of the East India elephant is better
than of the African. When it shows cracks or fissures in its substance,
and when a splinter broken off has a dull aspect, it is reckoned of
inferior value. Ivory is distinguishable from bone by its peculiar
semi-transparent rhombohedral net-work, which may be readily seen in
slips of ivory cut transversely.

Ivory is very apt to take a yellow-brown tint by exposure to air. It may
be whitened or bleached, by rubbing it first with pounded pumice-stone
and water, then placing it moist under a glass shade luted to the sole
at the bottom, and exposing it to sunshine. The sunbeams without the
shade would be apt to occasion fissures in the ivory. The moist rubbing
and exposure may be repeated several times.

For etching ivory, a ground made by the following recipe is to be
applied to the polished surface:--Take of pure white wax, and
transparent tears of mastick, each one ounce; asphalt, half an ounce.
The mastick and asphalt having been separately reduced to fine powder,
and the wax being melted in an earthenware vessel over the fire, the
mastick is to be first slowly strewed in and dissolved by stirring; and
then the asphalt in like manner. This compound is to be poured out into
lukewarm water, well kneaded, as it cools, by the hand, into rolls or
balls about one inch in diameter. These should be kept wrapped round
with taffety. If white rosin be substituted for the mastick, a cheaper
composition will be obtained, which answers nearly as well; 2 oz.
asphalt, 1 oz. rosin, 1/2 oz. white wax; being good proportions.
Callot’s etching ground for copper plates, is made by dissolving with
heat 4 oz. of mastick in 4 oz. of very fine linseed oil; filtering the
varnish through a rag, and bottling it for use.

Either of the two first grounds being applied to the ivory, the figured
design is to be traced through it in the usual way, a ledge of wax is to
be applied, and the surface is to be then covered with strong sulphuric
acid. The effect comes better out with the aid of a little heat; and by
replacing the acid, as it becomes dilute by absorption of moisture, with
concentrated oil of vitriol. Simple wax may be employed instead of the
copperplate engravers’ ground; and strong muriatic acid instead of
sulphuric. If an acid solution of silver or gold be used for etching,
the design will become purple or black, on exposure to sunshine. The wax
may be washed away with oil of turpentine. Acid nitrate of silver
affords the easiest means of tracing permanent black lines upon ivory.

Ivory may be dyed by using the following prescriptions:--

1. _Black dye._--If the ivory be laid for several hours in a dilute
solution of neutral nitrate of pure silver, with access of light, it
will assume a black colour, having a slightly green cast. A still finer
and deeper black may be obtained by boiling the ivory for some time in a
strained decoction of logwood, and then steeping it in a solution of red
sulphate or red acetate of iron.

2. _Blue dye._--When ivory is kept immersed for a longer or shorter time
in a dilute solution of sulphate of indigo (partly saturated with
potash), it assumes a blue tint of greater or less intensity.

3. _Green dye._--This is given by dipping blued ivory for a little while
in solution of nitromuriate of tin, and then in a hot decoction of
fustic.

4. _Yellow dye_--is given by impregnating the ivory first with the above
tin mordant, and then digesting it with heat in a strained decoction of
fustic. The colour passes into orange, if some brazil wood has been
mixed with the fustic. A very fine unchangeable yellow may be
communicated to ivory by steeping it 18 or 24 hours in a strong solution
of the neutral chromate of potash, and then plunging it for some time in
a boiling hot solution of acetate of lead.

5. _Red dye_--may be given by imbuing the ivory first with the tin
mordant, then plunging it in a bath of brazil wood, cochineal, or a
mixture of the two. Lac-dye may be used with still more advantage, to
produce a scarlet tint. If the scarlet ivory be plunged for a little in
a solution of potash, it will become cherry red.

6. _Violet dye_--is given in the logwood bath, to ivory previously
mordanted for a short time with solution of tin. When the bath becomes
exhausted, it imparts a lilac hue. Violet ivory is changed to purple-red
by steeping it a little while in water containing a few drops of
nitro-muriatic acid.

With regard to dyeing ivory, it may in general be observed, that the
colours penetrate better before the surface is polished than afterwards.
Should any dark spots appear, they may be cleared up by rubbing them
with chalk; after which the ivory should be dyed once more to produce
perfect uniformity of shade. On taking it out of the boiling hot dye
bath, it ought to be immediately plunged into cold water, to prevent the
chance of fissures being caused by the heat.

If the borings and chips of the ivory-turner, called ivory dust, be
boiled in water, a kind of fine size is obtained.

The importation of elephants’ teeth for home consumption was, in 1834,
4,282 cwts.; in 1835, 3,698, and in 1836, 4,584 cwts.; duty, 1_l._ per
cwt.


IVORY BLACK (_Noir d’ivoire_, Fr.; _Kohle von Elfenbein_, Germ.); is
prepared from ivory dust, by calcination in the very same way as is
described under BONE BLACK.

The calcined matter being ground and levigated on a porphyry slab,
affords a beautiful velvety black, much used in copperplate printing.
Ivory black may be prepared upon the small scale, by a well regulated
ignition of the ivory dust in a covered crucible.




K.


KALI. The Arabs gave this name to an annual plant which grows near the
sea-shore; now known under the name of _salsola soda_, and from whose
ashes they extracted a substance, which they called _alkali_, for making
soap. The term _kali_ is used by German chemists to denote caustic
potash; and _kalium_, its metallic basis; instead of our _potassa_ and
_potassium_, of preposterous pedigree, being derived from the words _pot
ashes_, that is ashes prepared in a pot.


KAOLIN, (_Terre à porcelaine_, Fr.; _Porzellanerde_, Germ.), is the name
given by the Chinese to the fine white clay with which they fabricate
the biscuit of their porcelains. See CLAY. Berthier’s analyses of two
porcelain earths are as follows:--

  +-------------+------------+-----------------+
  |  Analyses.  |From Passau.|From Saint Yriex.|
  +-------------+------------+-----------------+
  |Silica       |   45·06    |      46·8       |
  |Alumina      |   32·00    |      37·3       |
  |Lime         |    0·74    |       --        |
  |Oxide of iron|    0·90    |       --        |
  |Potass       |    --      |       2·5       |
  |Water        |   18·0     |      13·0       |
  |             +------------+-----------------+
  |             |   96·7     |      99·6       |
  +-------------+------------+-----------------+


KARABÉ, a name of amber, of Arabic origin, in use upon the Continent.


KELP; (_Varec_, Fr.; _Wareck_, Germ.), is the crude alkaline matter
produced by incinerating various species of fuci, or _sea-weed_. They
are cut with sickles from the rocks in the summer season, dried and then
burned, with much stirring of the pasty ash. I have analyzed many
specimens of kelp, and found the quantity of soluble matter in 100 parts
of the best to be from 53 to 62, while the insoluble was from 47 to 38.
The soluble consisted of--

  Sulphate of Soda                      8·0      19·0
  Soda in carbonate and sulphuret       8·5       5·5
  Muriate of soda and potash           36·5      37·5
                                       ----      ----
                                       53·0      62·0

The insoluble matter consisted of--

  Carbonate of lime                   24·0       10·0
  Silica                               8·0        0·0
  Alumina tinged with iron oxide       9·0       10·0
  Sulphate of lime                     0·0        9·5
  Sulphur and loss                     6·0        8·5
                                     -----      -----
                                     100·0      100·0

The first of these specimens was from Heisker, the second from Rona,
both in the isle of Skye, upon the property of Lord Macdonald. From
these, and many other analyses which I have made, it appears that kelp
is a substance of very variable composition, and hence it was very apt
to produce anomalous results, when employed as the chief alkaline flux
of crown glass, which it was for a very long period. The _fucus
vesiculosus_ and _fucus nodosus_ are reckoned to afford the best kelp by
incineration; but all the species yield a better product when they are
of two or three years growth, than when cut younger. The _varec_, made
on the shores of Normandy, contains almost no carbonate of soda, but
much sulphate of soda and potash, some hyposulphate of potash, chloride
of sodium, iodide of potassium, and chloride of potassium; the average
composition of the soluble salts being, according to M. Gay Lussac, 56
of chloride of sodium, 25 of chloride of potassium, and a little
sulphate of potash. The very low price at which soda ash, the dry crude
carbonate from the decomposition of sea salt, is now sold, has nearly
superseded the use of kelp, and rendered its manufacture utterly
unprofitable--a great misfortune to the Highlands and Islands of
Scotland.


KERMES. There are two substances so called, of totally different
natures. _Kermes mineral_ is merely a factitious sulphuret of antimony
in a state of impalpable comminution, prepared in the moist way. Its
minute examination belongs to pharmaceutical chemistry. It may be
obtained perfectly pure, by diluting the proto-chloride of antimony with
solution of tartaric acid, and precipitating the metal with sulphuretted
hydrogen; or by exposing the finely levigated native sulphuret to a
boiling solution of carbonate of potash for some time, and filtering the
liquor while boiling hot. The kermes falls down in a brown-red powder,
as the liquor cools.

_Kermes-grains_, _alkermes_, are the dried bodies of the female insects
of the species _coccus ilicis_, which lives upon the leaves of the
_quercus ilex_ (prickly oak). The word _kermes_ is Arabic, signifies
little worm. In the middle ages, this dye stuff was therefore called
_vermiculus_ in Latin, and _vermillion_ in French. It is curious to
consider how the name _vermillion_ has been since transferred to red
sulphuret of mercury.

Kermes has been known in the East since the days of Moses; it has been
employed from time immemorial in India to dye silk; and was used also by
the ancient Greek and Roman dyers. Pliny speaks of it under the name of
_coccigranum_, and says that there grew upon the oak in Africa, Sicily,
&c. a small excrescence like a bud, called _cusculium_; that the
Spaniards paid with these grains, half of their tribute to the Romans;
that those produced in Sicily were the worst; that they served to dye
purple; and that those from the neighbourhood of Emerita in Lusitania
(Portugal) were the best.

In Germany, during the ninth, twelfth, thirteenth, and fourteenth
centuries, the rural serfs were bound to deliver annually to the
convents, a certain quantity of kermes, the _coccus polonicus_, among
the other products of husbandry. It was collected from the trees upon
Saint John’s day, between eleven o’clock and noon, with religious
ceremonies, and was therefore called _Johannisblut_, (Saint John’s
blood), as also German cochineal. At the above period, a great deal of
the German kermes was consumed in Venice, for dyeing the scarlet to
which that city gives its name. After the discovery of America,
cochineal having been introduced, began to supersede kermes for all
brilliant red dyes.

The principal varieties of kermes are the _coccus quercus_, the _coccus
polonicus_, the _coccus fragariæ_, and the _coccus uva ursi_.

The _coccus quercus_ insect lives in the south of Europe upon the kermes
oak. The female has no wings, is of the size of a small pea, of a
brownish-red colour, and is covered with a whitish dust. From the middle
of May to the middle of June the eggs are collected, and exposed to the
vapour of vinegar, to prevent their incubation. A portion of eggs is
left upon the tree for the maintenance of the brood. In the department
of the Bouches-du-Rhone, one half of the kermes crop is dried. It
amounts annually to about 60 quintals or cwts., and is warehoused at
Avignon.

The kermes of Poland, or _coccus polonicus_, is found upon the roots of
the _scleranthus perennis_ and the _scleranthus annuus_, in sandy soils
of that country and the Ukraine. This species has the same properties as
the preceding; one pound of it, according to Wolfe, being capable of
dyeing 10 pounds of wool; but Hermstaedt could not obtain a fine colour,
although he employed 5 times as much of it as of cochineal. The Turks,
Armenians, and Cossacks, dye with kermes, their morocco leather, cloth,
silk, as well as the manes and tails of their horses.

The kermes called _coccus fragariæ_, is found principally in Siberia,
upon the root of the common strawberry.

The _coccus uva ursi_ is twice the size of the Polish kermes, and dyes
with alum a fine red. It occurs in Russia.

Kermes is found not only upon the _lycopodium complanatum_ in the
Ukraine, but upon a great many other plants.

Good kermes is plump, of a deep red colour, of an agreeable smell, and a
rough and pungent taste. Its colouring matter is soluble in water and
alcohol; it becomes yellowish or brownish with acids, and violet or
crimson with alkalis. Sulphate of iron blackens it. With alum it dyes a
blood-red; with copperas an agate gray; with copperas and tartar, a
lively gray; with sulphate of copper and tartar, an olive green; with
tartar and salt of tin, a lively cinnamon yellow; with more alum and
tartar, a lilac; with sulphate of zinc and tartar, a violet. Scarlet and
crimson dyed with kermes, were called _grain colours_; and they are
reckoned to be more durable than those of cochineal, as is proved by the
brilliancy of the old Brussels tapestry.

Hellot says that previous to dyeing in the kermes bath, he threw a
handful of wool into it, in order to extract a blackish matter, which
would have tarnished the colour. The red caps for the Levant are dyed at
Orleans with equal parts of kermes and madder; and occasionally with the
addition of some Brazil wood.

Cochineal and lac-dye have now nearly superseded the use of kermes as a
tinctorial substance, in England.


KILLAS, is the name by which clay-slate is known among the Cornish
miners.


KILN; (_Four_, Fr.; _Ofen_, Germ.) is the name given to various forms of
furnaces and stoves, by which an attempered heat may be applied to
bodies; thus there are brick-kilns, hop-kilns, lime-kilns, malt-kilns,
pottery-kilns. Hop and malt kilns, being designed merely to expel the
moisture of the vegetable matter, may be constructed in the same way.
See BRICK, LIMESTONE, MALT, POTTERY, for a description of their
respective kilns.


KINIC ACID; a peculiar acid extracted by Vauquelin from cinchona.


KINO, is an extractive matter obtained from the _nauclea gambir_, a
shrub which grows at Bancoul and Sumatra, but principally in Prince of
Wales’ Island. It is of a reddish-brown colour, has a bitter styptic
taste, and consists chiefly of tannin. It is used only as an astringent
in medicine. Kino is often called a gum, but most improperly.


KIRSCHWASSER, is an alcoholic liquor obtained by fermenting and
distilling bruised cherries, called _kirschen_ in German. The cherry
usually employed in Switzerland and Germany is a kind of morello, which
on maturation becomes black, and has a kernel very large in proportion
to its pulp. When ripe, the fruit being made to fall by switching the
trees, is gathered by children, thrown promiscuously, unripe, ripe, and
rotten into tubs, and crushed either by hand, or with a wooden beater.
The mashed materials are set to ferment, and whenever this process is
complete, the whole is transferred to an old still covered with
verdigris, and the spirit is run off in the rudest manner possible, by
placing the pot over the common fire-place.

The fermented mash is usually mouldy before it is put into the alembic,
the capital of which is luted on with a mixture of mud and dung. The
liquor has accordingly, for the most part, a rank smell, and is most
dangerous to health, not only from its own crude essential oil, but from
the prussic acid, derived from the distillation of the cherry-stones.

There is a superior kind of _kirschwasser_ made in the Black Forest,
prepared with fewer kernels, from choice fruit, properly pressed,
fermented, and distilled.


KNOPPERN, are excrescences produced by the puncture of an insect upon
the flower-cups of several species of oak. They are compressed or flat,
irregularly pointed, generally prickly and hard; brown when ripe. They
abound in Styria, Croatia, Sclavonia, and Natolia; those from the latter
country being the best. They contain a great deal of tannin, are much
employed in Austria for tanning, and in Germany for dyeing fawn, gray,
and black. Wool, with a mordant of sulphate of zinc, takes a grayish
nankeen colour. See GALLS.


KOUMISS, is the name of a liquor which the Calmucs make by fermenting
mare’s milk, and from which they distil a favourite intoxicating spirit,
called _rack_ or _racky_. Cow’s milk is said to produce only one third
as much spirit, from its containing probably less saccharine matter.

The milk is kept in bottles made of hides, till it becomes sour, is
shaken till it casts up its cream, and is then set aside in earthen
vessels in a warm place to ferment, no yeast being required, though
sometimes a little old koumiss is added. 21 pounds of milk put into the
still afford 14 ounces of low wines, from which 6 ounces of pretty
strong alcohol, of an unpleasant flavour, are obtained by
rectification.




L.


LABDANUM or LADANUM, is an unctuous resin, of an agreeable odour, found
besmearing the leaves and twigs of the _cystus creticus_, a plant which
grows in the island of Candia, and in Syria. It is naturally a
dark-brown soft substance, but it hardens on keeping. Its specific
gravity is 1·186. It has a bitter taste. Its chief use is in surgery for
making plasters.


LABRADORITE; opaline or Labradore felspar, is a beautiful mineral, with
brilliant changing colours, blue, red, and green, &c. Spec. grav. 2·70
to 2·75. Scratches glass; affords no water by calcination; fusible at
the blow-pipe into a frothy bead; soluble in muriatic acid; solution
affords a copious precipitate with oxalate of ammonia. Cleavages of
93-1/2° and 86-1/2°; one of which is brilliant and pearly. Its
constituents are, silica, 55·75; alumina, 26·5; lime, 11; soda, 4; oxide
of iron, 1·25; water, 0·5.


LABYRINTH, in metallurgy, means a series of canals distributed in the
sequel of a stamping-mill; through which canals a stream of water is
transmitted for suspending, carrying off, and depositing, at different
distances, the ground ores. See METALLURGY.


LAC, LAC-DYE. (_Laque_, Fr.; _Lack_, _Lackfarben_, Germ.) _Stick-lac_ is
produced by the puncture of a peculiar female insect, called _coccus
lacca_ or _ficus_, upon the branches of several plants; as the _ficus
religiosa_, the _ficus indica_, the _rhamnus jujuba_, the _croton
lacciferum_, and the _butea frondosa_, which grow in Siam, Assam, Pegu,
Bengal, and Malabar. The twig becomes thereby encrusted with a reddish
mammelated resin, having a crystalline-looking fracture.

The female lac insect is of the size of a louse; red, round, flat, with
12 abdominal circles, a bifurcated tail, antennæ, and 6 claws, half the
length of the body. The male is twice the above size, and has 4 wings;
there is one of them to 5000 females. In November or December the young
brood makes its escape from the eggs, lying beneath the dead body of the
mother; they crawl about a little way, and fasten themselves to the bark
of the shrubs. About this period the branches often swarm to such a
degree with this vermin, that they seem covered with a red dust; in this
case, they are apt to dry up, by being exhausted of their juices. Many
of these insects, however, become the prey of others, or are carried off
by the feet of birds, to which they attach themselves, and are
transplanted to other trees. They soon produce small nipple-like
incrustations upon the twigs, their bodies being apparently glued, by
means of a transparent liquor, which goes on increasing to the end of
March, so as to form a cellular texture. At this time, the animal
resembles a small oval bag, without life, of the size of cochineal. At
the commencement, a beautiful red liquor only is perceived, afterwards
eggs make their appearance; and in October or November, when the red
liquor gets exhausted, 20 or 30 young ones bore a hole through the back
of their mother, and come forth. The empty cells remain upon the
branches. These are composed of the milky juice of the plant, which
serves as nourishment to the insects, and which is afterwards
transformed or elaborated into the red colouring matter that is found
mixed with the resin, but in greater quantity in the bodies of the
insects, in their eggs, and still more copiously in the red liquor
secreted for feeding the young. After the brood escapes, the cells
contain much less colouring matter. On this account, the branches should
be broken off before this happens, and dried in the sun. In the East
Indies this operation is performed twice in the year; the first time in
March, the second in October. The twigs encrusted with the radiated
cellular substance, constitute the _stick-lac_ of commerce. It is of a
red colour more or less deep, nearly transparent, and hard, with a
brilliant conchoidal fracture. The stick-lac of Siam is the best; a
piece of it presented to me by Mr. Rennie, of Fenchurch-street, having
an incrustation fully one quarter of an inch thick all round the twig.
The stick-lac of Assam ranks next; and, last, that of Bengal, in which
the resinous coat is scanty, thin, and irregular. According to the
analysis of Dr. John, stick-lac consists, in 120 parts, of

  An odorous common resin                              80·00
  A resin insoluble in ether                           20·00
  Colouring matter analogous to that of cochineal       4·50
  Bitter balsamic matter                                3·00
  Dun yellow extract                                    0·50
  Acid of the stick-lac (laccic acid)                   0·75
  Fatty matter, like wax                                3·00
  Skins of the insects, and colouring matter            2·50
  Salts                                                 1·25
  Earths                                                0·75
  Loss                                                  4·75
                                                      ------
                                                      120·00

According to Franke, the constituents of stick-lac are, resin, 65·7;
substance of the lac, 28·3; colouring matter, 0·6.

_Seed-lac._--When the resinous concretion is taken off the twigs,
coarsely pounded, and triturated with water in a mortar, the greater
part of the colouring matter is dissolved, and the granular portion
which remains being dried in the sun, constitutes _seed-lac_. It
contains of course less colouring matter than the stick-lac, and is much
less soluble. John found in 100 parts of it, resin, 66·7; wax, 1·7;
matter of the lac, 16·7; bitter balsamic matter, 2·5; colouring matter,
3·9; dun yellow extract, 0·4; envelopes of insects, 2·1; laccic acid,
0·0; salts of potash and lime, 1·0; earths, 6·6; loss, 4·2.

In India the _seed-lac_ is put into oblong bags of cotton cloth, which
are held over a charcoal fire by a man at each end, and, as soon as it
begins to melt, the bag is twisted so as to strain the liquefied resin
through its substance, and to make it drop upon smooth stems of the
banyan tree (_musa paradisa_). In this way, the resin spreads into thin
plates, and constitutes the substance known in commerce by the name of
_shell-lac_.

The Pegu stick-lac, being very dark coloured, furnishes a shell-lac of a
corresponding deep hue, and therefore of inferior value. The palest and
finest shell-lac is brought from the northern _Circar_. It contains very
little colouring matter. A stick-lac of an intermediate kind comes from
the Mysore country, which yields a brilliant lac-dye and a good
shell-lac.

_Lac-dye_ is the watery infusion of the ground stick-lac, evaporated to
dryness, and formed into cakes about two inches square and half an inch
thick. Dr. John found it to consist of, colouring matter, 50; resin, 25;
and solid matter, composed of alumina, plaster, chalk, and sand, 22.

Dr. Macleod, of Madras, informs me that he prepared a very superior
lac-dye from stick-lac, by digesting it in the cold in a slightly
alkaline decoction of the dried leaves of the _Memecylon tinctorium_
(perhaps the _M. capitellatum_, from which the natives of Malabar and
Ceylon obtain a saffron-yellow dye). This solution being used along with
a mordant consisting of a saturated solution of tin in muriatic acid,
was found to dye woollen cloth of a very brilliant scarlet hue.

The cakes of _lac-dye_ imported from India, stamped with peculiar marks
to designate their different manufacturers, are now employed exclusively
in England for dyeing scarlet cloth, and are found to yield an equally
brilliant colour, and one less easily affected by perspiration than that
produced by cochineal. When the lac-dye was first introduced, sulphuric
acid was the solvent applied to the pulverized cakes, but as muriatic
acid has been found to answer so much better, it has entirely supplanted
it. A good _solvent_ (No. 1.) for this dye-stuff may be prepared by
dissolving 3 pounds of tin in 60 pounds of muriatic acid, of specific
gravity 1·19. The proper _mordant_ for the cloth is made by mixing 27
pounds of muriatic acid of sp. grav. 1·17, with 1-1/2 pounds of nitric
acid of 1·19; putting this mixture into a salt-glazed stone bottle, and
adding to it in small bits at a time, grain tin, till 4 pounds be
dissolved. This solution (No. 2.) may be used within twelve hours after
it is made, provided it has become cold and clear. For dyeing; three
quarters of a pint of the solvent No. 1. is to be poured upon each pound
of the pulverized lac-dye, and allowed to digest upon it for six hours.
The cloth before being subjected to the dye bath, must be scoured in the
mill with fullers’ earth. To dye 100 pounds of pelisse cloth, a tin
boiler of 300 gallons capacity should be filled nearly brimful with
water, and a fire kindled under it. Whenever the temperature rises to
150° Fahr., a handful of bran, and half a pint of the solution of tin
(No. 2.) are to be introduced. The froth, which rises as it approaches
ebullition, must be skimmed off; and when the liquor boils, 10-1/2
pounds of lac-dye, previously mixed with 7 pints of the solvent No. 1.,
and 3-1/2 pounds of solution of tin No. 2., must be poured in. An
instant afterwards, 10-1/2 pounds of tartar, and 4 pounds of ground
sumach, both tied up in a linen bag, are to be suspended in the boiling
bath for five minutes. The fire being now withdrawn, 20 gallons of cold
water, with 10-1/2 pints of solution of tin being poured into the bath,
the cloth is to be immersed in it, moved about rapidly during ten
minutes; the fire is to be then re-kindled, and the cloth winced more
slowly through the bath, which must be made to boil as quickly as
possible, and maintained at that pitch for an hour. The cloth is to be
next washed in the river; and lastly with water only, in the fulling
mill. The above proportions of the ingredients produce a brilliant
scarlet tint, with a slightly purple cast. If a more orange hue be
wanted, white Florence argal may be used, instead of tartar, and some
more sumach. Lac-dye may be substituted for cochineal in the
orange-scarlets; but for the more delicate pink shades, it does not
answer so well, as the lustre is apt to be impaired by the large
quantity of acid necessary to dissolve the colouring matter of the lac.

_Shell-lac_, by Mr. Hatchett’s analysis, consists of resin, 90·5;
colouring matter, 0·5; wax, 4·0; gluten, 2·8; loss, 1·8; in 100 parts.

The resin may be obtained pure by treating shell-lac with cold alcohol,
and filtering the solution in order to separate a yellow gray
pulverulent matter. When the alcohol is again distilled off, a brown,
translucent, hard, and brittle resin, of specific gravity 1·139,
remains. It melts into a viscid mass with heat, and diffuses an aromatic
odour. Anhydrous alcohol dissolves it in all proportions. According to
John, it consists of two resins, one of which dissolves readily in
alcohol, ether, the volatile and fat oils; while the other is little
soluble in cold alcohol, and is insoluble in ether and the volatile
oils. Unverdorben, however, has detected no less than four different
resins, and some other substances in shell-lac. Shell-lac dissolves with
ease in dilute muriatic and acetic acids; but not in concentrated
sulphuric acid. The resin of shell-lac has a great tendency to combine
with salifiable bases; as with caustic potash, which it deprives of its
alkaline taste.

This solution, which is of a dark red colour, dries into a brilliant,
transparent, reddish brown mass; which may be re-dissolved in both water
and alcohol. By passing chlorine in excess through the dark-coloured
alkaline solution, the lac-resin is precipitated in a colourless state.
When this precipitate is washed and dried, it forms, with alcohol, an
excellent pale-yellow varnish, especially with the addition of a little
turpentine and mastic.

With the aid of heat, shell-lac dissolves readily in a solution of
borax.

The substances which Unverdorben found in shell-lac are the following:

1. A resin, soluble in alcohol and ether;

2. A resin, soluble in alcohol, insoluble in ether;

3. A resinous body, little soluble in cold alcohol;

4. A crystallizable resin;

5. A resin, soluble in alcohol and ether, but insoluble in petroleum,
and uncrystallizable.

6. The unsaponified fat of the _coccus_ insect, as well as oleic and
margaric acids.

7. Wax.

8. The _laccine_ of Dr. John.

9. An extractive colouring matter.

STATISTICAL TABLE of LAC-DYE and LAC-LAKE, per favour of James
Wilkinson, Esq., of Leadenhall-street.

  +----+---------+-------+-------------+-------------+---------+
  |    | Import. |Export.|    Home     |   Prices.   | Stocks. |
  |    |         |       |Consumption. |             |         |
  +----+---------+-------+-------------+-------------+---------+
  |    |  _lbs._ | _lbs._|   _lbs._    |_s. d. s. d._|_Chests._|
  |1802|      253|  none |    none     |             |         |
  |1803|    1,735|       |accot. burned|             |         |
  |1804|      531|       |             |             |         |
  |1805|    1,987|       |             |             |         |
  |1806|    none |       |             |             |         |
  |1807|   25,350|       |             |             |         |
  |1808|    5,731|       |             |             |         |
  |1809|   40,632|       |             |             |         |
  |1810|  235,154|       |             |             |         |
  |1811|  378,325|       |             |             |         |
  |1812|  198,250|       |             |             |         |
  |1813|  289,654|       |             |             |         |
  |1814|  278,899|  5,071|   133,935   |             |         |
  |1815|  598,592|  8,441|   137,915   |             |         |
  |1816|  269,373| 27,412|   162,894   |             |         |
  |1817|  384,909| 23,091|   234,763   |             |         |
  |1818|  242,572| 32,079|   323,169   |             |         |
  |1819|  179,511| 21,707|   207,063   |             |         |
  |1820|  441,486| 49,519|   912,514   |             |         |
  |1821|  641,755| 91,925|   322,837   |             |         |
  |1822|  872,967| 29,578|   349,351   |             |         |
  |1823|  534,220| 13,050|   414,714   |             |         |
  |1824|  604,269| 53,843|   483,339   |             |         |
  |1825|  541,443| 61,908|   385,734   |             |         |
  |1826|  760,729| 68,603|   395,609   |             |         |
  |1827|  756,315| 76,875|   448,270   | 1  9  4  0  |  11,538 |
  |1828|  512,874| 54,999|   397,867   | 1  3  3  9  |  11,085 |
  |1829|  475,632| 39,344|   433,851   | 1  3  3  6  |  11,976 |
  |1830|  534,341| 78,099|   548,865   | 0  9  3  3  |  11,834 |
  |1831|  913,562|175,717|   597,568   | 0  4  2  6  |  12,559 |
  |1832|  378,843| 69,842|   594,155   | 0  4  2  3  |  11,420 |
  |1833|  326,894| 66,447|   426,460   | 0  9  2  4  |  11,457 |
  |1834|  708,959| 89,229|   398,832   | 0 11  2  4  |  11,928 |
  |1835|  528,564|203,840|   573,288   | 0 11  3  0  |  10,454 |
  |1836|  642,436|200,975|   642,615   | 1  0  4  0  |   9,492 |
  |1837|1,011,674|133,959|   427,890   | 1  0  3  9  |   8,780 |
  +----+---------+-------+-------------+-------------+---------+
  |        The Stock includes 2,200 chests of Lac-lake.        |
  +------------------------------------------------------------+


LACCIC ACID crystallizes, has a wine-yellow colour, a sour taste, is
soluble in water, alcohol, and ether. It was extracted from stick-lac by
Dr. John.


LACCINE is the portion of shell-lac which is insoluble in boiling
alcohol. It is brown, brittle, translucid, consisting of agglomerated
pellicles, more like a resin than any thing else. It is insoluble in
ether and oils. It has not been applied to any use.


LACE MANUFACTURE. The pillow-made, or bone-lace, which formerly gave
occupation to multitudes of women in their own houses, has, in the
progress of mechanical invention, been nearly superseded by the
bobbin-net lace, manufactured at first by hand-machines, as stockings
are knit upon frames, but recently by the power of water or steam. This
elegant texture possesses all the strength and regularity of the old
Buckingham lace, and is far superior in these respects to the point-net
and warp lace, which had preceded, and in some measure paved the way for
it. Bobbin-net may be said to surpass every other branch of human
industry in the complex ingenuity of its machinery; one of Fisher’s
spotting frames being as much beyond the most curious chronometer in
multiplicity of mechanical device, as that is beyond a common
roasting-jack.

[Illustration: 608]

The threads in bobbin-net lace form, by their intertwisting and
decussation, regular hexagonal holes or meshes, of which the two
opposite sides, the upper and under, are directed along the breadth of
the piece, or at right angles to the selvage or border. _Fig._ 608.
shows how, by the crossing and twisting of the threads, the regular
six-sided mesh is produced, and that the texture results from the union
of three separate sets of threads, of which one set proceed downwards in
serpentine lines, a second set proceeds from the left to the right, and
a third from the right to the left, both in slanting directions. These
oblique threads twist themselves round the vertical ones, and also cross
each other betwixt them, in a peculiar manner, which may be readily
understood by examining the representation. In comparing bobbin-net with
a common web, the perpendicular threads in the figure, which are
parallel to the border, may be regarded as the warp, and the two sets of
slanting threads, as the weft.

[Illustration: 609]

These warp threads are extended up and down, in the original mounting of
the piece between a top and bottom horizontal roller or beam, of which
one is called the warp beam, and the other the lace beam, because the
warp and finished lace are wound upon them respectively. These straight
warp threads receive their contortion from the tension of the weft
threads twisted obliquely round them alternately to the right and the
left hand. Were the warp threads so tightly drawn that they became
inflexible, like fiddle-strings, then the lace would assume the
appearance shown in _fig._ 609.; and although this condition does not
really exist, it may serve to illustrate the structure of the web. The
warp threads stand in the positions _a a_, _a´ a´_, and _a´´ a´´_; the
one half of the weft proceeds in the direction _b b_, _b´ b´_ and _b´´
b´´_; and the second crosses the first by running in the direction _c
c_, or _c´ c´_, towards the opposite side of the fabric. If we pursue
the path of a weft thread, we find it goes on till it reaches the
outermost or last warp thread, which it twists about; not once, as with
the others, but twice; and then returning towards the other border,
proceeds in a reverse direction. It is by this double twist, and by the
return of the weft threads, that the selvage is made.

The ordinary material of bobbin-net is two cotton yarns, of from No.
180. to No. 250., twisted into one thread; but sometimes strongly
twisted single yarn has been used. The beauty of the fabric depends upon
the quality of the material, as well as the regularity and smallness of
the meshes. The number of warp threads in a yard in breadth is from 600
to 900; which is equivalent to from 20 to 30 in an inch. The size of the
holes cannot be exactly inferred from that circumstance, as it depends
partly upon the oblique traction of the threads. The breadth of the
pieces of bobbin-net varies from edgings of a quarter of an inch, to
webs 12, or even 20 quarters, that is, 5 yards wide.

[Illustration: 610 611]

Bobbin-net lace is manufactured by means of very costly and complicated
machines, called _frames_. The limits of this Dictionary will admit of
an explanation of no more than the general principles of the
manufacture. The threads for crossing and twisting round the warp, being
previously gassed, that is, freed from loose fibres by singeing with
gas, are wound round small pulleys, called bobbins, which are, with this
view, deeply grooved in their periphery. _Figs._ 610, 611. exhibit the
bobbin alone, and with its carriage. In the section of the bobbin _a_,
_fig._ 610., the deep groove is shown in which the thread is wound. The
bobbin consists of two thin discs of brass, cut out in a stamp-press, in
the middle of each of which there is a hollow space _c_. These discs are
riveted together, leaving an interval between their edge all round, in
which the thread is coiled. The round hole in the centre, with the
little notch at top, serves for spitting them upon a feathered rod, in
order to be filled with thread by the rotation of that rod in a species
of reel, called the bobbin-filling machine. Each of these bobbins (about
double the size of the figure), is inserted into the vacant space G of
the carriage, _fig._ 611. This is a small iron frame (also double the
size of the figure), which, at _e e_, embraces the grooved border of the
bobbin, and by the pressure of the spring at _f_, prevents it from
falling out. This spring serves likewise to apply sufficient friction to
the bobbin, so as to prevent it from giving off its thread at _g_ by its
rotation, unless a certain small force of traction be employed upon the
thread. The curvilinear groove _h h_, sunk in each face or side of the
carriage, has the depth shown in the section at _h_. This groove
corresponds to the interval between the teeth of the comb, or bars of
the bolt, in which each carriage is placed, and has its movement. A
portion of that bolt or comb is shown at _a_, _fig._ 612. in plan, and
one bar of a circular bolt machine at _b_, in section. If we suppose two
such combs or bolts placed with the ends of the teeth opposite each
other, but a little apart, to let the warp threads be stretched, in one
vertical plane, between their ends or tips, we shall have an idea of the
skeleton of a bobbin-net machine. One of these two combs, in the double
bolt machine, has an occasional lateral movement called _shogging_,
equal to the interval of one tooth or bolt, by which, after it has
received the bobbins, with their carriages, into its teeth, it can shift
that interval to the one side, and thereby get into a position to return
the bobbins, with their carriages, into the next series of interstices
or gates, in the other bolt. By this means the whole series of carriages
receives successive side steps to the right in one bolt, and to the left
in the other, so as to perform a species of countermarch, in the course
of which they are made to cross and twist round about the vertical warp
threads, and thus to form the meshes of the net.

[Illustration: 612]

The number of movements required to form a row of meshes in the double
tier machine, that is, in a frame with two combs or bars, and 2 rows of
bobbins, is six; that is, the whole of the carriages (with their
bobbins) pass from one bar or comb to the other six times, during which
passages the different divisions of bobbin and warp threads change their
relative positions 12 times.

[Illustration: 613]

This interchange or traversing of the carriages with their bobbins,
which is the most difficult thing to explain, but at the same time the
most essential principle of the lace-machine, may be tolerably well
understood by a careful study of _fig._ 613., in which the simple line |
represents the bolts or teeth, the sign ● the back line of carriages,
and the sign ○ the front line of carriages. H is the front comb or bolt
bar, and I the back bolt bar. The former remain is always fixed or
stationary, to receive the carriages as they may be presented to it by
the shogging of the latter. There must be always one odd carriage at the
end; the rest being in pairs.

No. 1. represents the carriages in the front comb or bar, the odd
carriage being at the left end. The back line of carriages is first
moved on to the back bar I, the odd carriage, as seen in No. 1., having
been left behind, there being no carriage opposite to drive it over to
the other comb or bar. The carriages then stand as in No. 2. The bar I
now shifts to the left, as shown in No. 3.; the front carriages then go
over into the back bar or comb, as is represented by No. 4. The bar I
now shifts to the right, and gives the position No. 5. The front
carriages are then driven over to the front bar, and leave the odd
carriage on the back bar at the right end, for the same reason as before
described, and the carriages stand as shown in No. 6. The bar I next
shifts to the left, and the carriages stand as in No. 7. (the odd
carriage being thereby on the back bar to the left.) The back carriages
now come over to the front bar, and stand as in No. 8. The back bar or
comb I shifts to the right as seen in No. 9., which completes the
traverse. The whole carriages with their bobbins have now changed their
position, as will be seen by comparing No. 9. with No. 1. The odd
carriage, No. 1. ○ has advanced one step to the right, and has become
one of the front tier; one of the back tier or line ● has advanced one
step to the left, and has become the odd carriage; and one of the front
ones ○ has gone over to the back line. The bobbins and carriages
throughout the whole width of the machine have thus crossed each other’s
course, and completed the mesh of net.

The carriages with their bobbins are driven a certain way from the one
comb to the other, by the pressure of two long bars (one for each)
placed above the level of the comb, until they come into such a position
that their projecting heels or catches _i i_, _fig._ 611., are moved off
by two other long flat bars below, called the locker plates, and thereby
carried completely over the interval between the two combs.

There are six different systems of bobbin-net machines. 1. Heathcoate’s
patent machine. 2. Brown’s traverse warp. 3. Morley’s straight bolt. 4.
Clarke’s pusher principle, single tier. 5. Leaver’s machine, single
tier. 6. Morley’s circular bolt. All the others are mere variations in
the construction of some of their parts. It is a remarkable fact, highly
honourable to the mechanical judgment of Mr. Morley of Derby, that no
machines except those upon his circular bolt principle, have been found
capable of working successfully by mechanical power.

The circular bolt machine (comb with curved teeth) was used by Mr.
Morley, for making narrow breadths or edgings of lace immediately after
its first invention, and it has been regularly used by the trade for
that purpose ever since, in consequence of the inventor having declined
to secure the monopoly of it to himself by patent. At that time the
locker bars for driving across the carriages had only one plate or
blade. A machine so mounted is now called “the single locker circular
bolt.” In the year 1824, Mr. Morley added another plate to each of the
locker bars, which was a great improvement on the machines for making
plain net, but an obstruction to the making of narrow breadths upon
them. This machine is now distinguished from the former by the term
“double locker.”[31]

  [31] By reading the above brief account of Bobbin-net, in connexion
  with the more detailed description of it in my COTTON MANUFACTURE OF
  GREAT BRITAIN, a tolerably clear conception of the nature of this
  intricate manufacture may be obtained.

A rack of lace, is a certain length of work counted perpendicularly, and
contains 240 meshes or holes. Well-made lace has the meshes a little
elongated in the direction of the selvage.

The term gauge, in the lace manufacture, means the number of gates,
slits, or interstices, in one inch of the bolt-bar or comb; and
corresponds therefore to the number of bobbins in an inch length of the
double tier. Thus, when we say “gauge nine points,” we mean that there
are nine gates with nine bobbins in one inch of the comb or bolt-bar.
Each of such bobbins with its carriage is therefore no more than one
ninth of an inch thick. The common proportion or gauge up and down the
machine is 16 holes in the inch for ten bobbins transversely. Circular
bolt double tier machines can turn off by steam power fully 360 racks
each day of 18 hours, with a relay of superintendents.

The number of new mechanical contrivances to which this branch of
manufacture has given rise, is altogether unparalleled in any other
department of the arts. Since Mr. Heathcoate’s first successful patent,
in 1809, a great many other patents have been granted for making lace.
In the year 1811, Mr. Morley, then of Nottingham, invented his straight
bolt frame, more simple in construction, better combined, and more easy
in its movements, than the preceding machines; but the modest inventor
did not secure it, as he might have done, by patent. The pusher machine
was invented in the same year, by Samuel Mart and James Clark, also of
Nottingham. The following year is remarkable in the history of the lace
trade, for the invention of the circular bolt machine, by Mr. Morley--a
mechanism possessing all the advantages of his straight bolt machine,
without its disadvantages.

Nearly at the same time Mr. John Leaver brought forward the lever
machine, conjointly with one Turton, both of New Radford, near
Nottingham. About the year 1817, or 1818, Mr. Heathcoate applied the
rotatory movement to the circular bolt machine, and mounted a
manufactory on that plan, by mechanical power, at Tiverton, after he and
his partner, Mr. Boden, had been driven from Loughborough, in 1816, by
the atrocious violence of the frame-destroying Luddites.

Such has been the progress of improvement and economy in this
manufacture, that the cost of labour in making a _rack_, which was,
twenty years ago, 3_s._ 6_d._, or 42 pence, is now not more than one
penny. The prices of this beautiful fabric have fallen in an equally
remarkable manner. At the former period, a 24 rack piece, five quarters
broad, fetched 17_l._ sterling, in the wholesale market; the same is now
sold for 7_s._! The consequence is, that in lace decoration, the maid
servant may now be more sumptuously arrayed than her mistress could
afford to be twenty years ago.


LACQUER, is a varnish, consisting chiefly of a solution of pale
shell-lac in alcohol, tinged with saffron, annotto, or other colouring
matters. See VARNISH.


LACTIC ACID. (_Acide Lactique_, Fr.; _Milchsäure_, Germ.) This acid was
discovered by Scheele in buttermilk, where it exists most abundantly;
but it is present also in fresh milk in small quantity, and communicates
to it the property of reddening litmus. Lactic acid may be detected in
all the fluids of the animal body; either free or saturated with
alkaline matter.

Scheele obtained this acid by evaporating the sour whey of clotted milk
to an eighth part of its bulk, saturating this remainder with slaked
lime, in order to throw down the subphosphate of lime held in solution,
filtering the liquor, diluting it with thrice its weight of water, and
precipitating the lime circumspectly, by the gradual addition of oxalic
acid. He next filtered, evaporated to dryness on a water bath, and
digested the residuum in strong alcohol, which dissolved the lactic
acid, and left the sugar of milk. On evaporating off the alcohol, the
acid was obtained. As thus procured, it requires to be purified by
saturation with carbonate of lead (pure white lead), and precipitating
the solution of this lactate with sulphate of zinc, not added in excess.
Sulphate of lead falls, and the supernatant lactate of zinc being
evaporated affords crystals, at first brown, but which become colourless
on being dissolved and re-crystallized twice or thrice. If the sulphuric
acid of the dissolved salt be thrown down by water of baryta, the liquid
when filtered and evaporated yields a pure lactic acid, of a syrupy
consistence, colourless and void of smell. It has a pungent acid taste,
which it loses almost entirely when moderately diluted with water. It
does not crystallize. Its salts, with the exception of those of magnesia
and zinc, have a gummy appearance, and are very soluble in alcohol,
unless they hold an excess of base. Lactic acid consists of 44·92
carbon; 6·55 hydrogen; 48·53 oxygen. It contains 9·92 per cent. of
water. It has not hitherto been applied to any use in the arts, except
by the Dutch in their old process of bleaching linen with sour milk.


LACTOMETER is the name of an instrument for estimating the quality of
milk, called also a _Galactometer_, which see. The most convenient form
of apparatus would be a series of glass tubes each about 1 inch in
diameter, and 12 inches long, graduated through a space of 10 inches, to
tenths of an inch, having a stop-cock at the bottom, and suspended
upright in a frame. The average milk of the cow being poured in to the
height of 10 inches, as soon as the cream has all separated at top, the
thickness of its body may be measured by the scale; and then the
skim-milk may be run off below into a hydrometer glass, in order to
determine its density, or relative richness in caseous matter.


LAKES. Under this title are comprised all those colours which consist of
a vegetable dye, combined by precipitation with a white earthy basis,
which is usually alumina. The general method of preparation is to add to
the coloured infusion a solution of common alum, or rather a solution of
alum saturated with potash, especially when the infusion has been made
with the aid of acids. At first only a slight precipitate falls,
consisting of alumina and the colouring matter; but on adding potash, a
copious precipitation ensues, of the alumina associated with the dye.
When the dyes are not injured, but are rather brightened by alkalis, the
above process is reversed; a decoction of the dye-stuff is made with an
alkaline liquor, and when it is filtered, a solution of alum is poured
into it. The third method is practicable only with substances having a
great affinity for subsulphate of alumina; it consists in agitating
recently precipitated alumina with the decoction of the dye.

_Yellow lakes_ are made with a decoction of Persian or French berries,
to which some potash or soda is added; into the mixture a solution of
alum is to be poured as long as any precipitate falls. The precipitate
must be filtered, washed, and formed into cakes, and dried. A lake may
be made in the same way with quercitron, taking the precaution to purify
the decoction of the dye-stuff with buttermilk or glue. After filtering
the lake it may be brightened with a solution of tin. Annotto lake is
formed by dissolving the dye-stuff in a weak alkaline lye, and adding
alum water to the solution. Solution of tin gives this lake a lemon
yellow cast; acids a reddish tint.

_Red lakes._--The finest of these is _carmine_.

This beautiful pigment was accidentally discovered by a Franciscan monk
at Pisa. He formed an extract of cochineal with salt of tartar, in order
to employ it as a medicine, and obtained, on the addition of an acid to
it, a fine red precipitate. Homberg published a process for preparing
it, in 1656. Carmine is the colouring matter of cochineal, prepared by
precipitation from a decoction of the drug. Its composition varies
according to the mode of making it. The ordinary carmine is prepared
with alum, and consists of _carminium_ (see COCHINEAL), a little animal
matter, alumina, and sulphuric acid. See CARMINE.

_Carminated lake_, called lake of Florence, Paris, or Vienna. For making
this pigment, the liquor is usually employed which is decanted from the
carmine process. Into this, newly precipitated alumina is put; the
mixture is stirred, and heated a little, but not too much. Whenever the
alumina has absorbed the colour, the mixture is allowed to settle, and
the liquor is drawn off.

Sometimes alum is dissolved in the decoction of cochineal, and potash is
then added, to throw down the alumina in combination with the colouring
matter; but in this way an indifferent pigment is obtained.
Occasionally, solution of tin is added, to brighten the dye.

A lake may be obtained from kermes, in the same way as from cochineal;
but now it is seldom had recourse to.

_Brazil-wood lakes._--Brazil wood is to be boiled in a proper quantity
of water for 15 minutes; then, alum and solution of tin being added, the
liquor is to be filtered, and a solution of potash poured in as long as
it occasions a precipitate. This is separated by the filter, washed in
pure water, mixed with a little gum water, and made into cakes. Or, the
Brazil wood may be boiled along with a little vinegar, the decoction
filtered, alum and salt of tin added, and then potash-lye poured in to
precipitate the lake. For 1 pound of Brazil wood, 30 to 40 pounds of
water, and from 1-1/2 to 2 pounds of alum, may be taken, in producing a
deep red lake; or, the same proportions with half a pound of solution of
tin. If the potash be added in excess, the tint will become violet.
Cream of tartar occasions a brownish cast.

_Madder lake._--A fine lake may be obtained from madder, by washing it
in cold water as long as it gives out colour; then sprinkling some
solution of tin over it, and setting it aside for some days. A gentle
heat may also be applied. The red liquor must be then separated by the
filter, and decomposed by the addition of carbonate of soda, when a fine
red precipitate will be obtained. Or, the reddish brown colouring matter
of a decoction of madder may be first separated by acetate of lead, and
then the rose-red colour with alum. Or, madder tied up in a bag is
boiled in water; to the decoction, alum is added, and then potash. The
precipitate should be washed with boiling water, till it ceases to tinge
it yellow; and it is then to be dried.

The following process merits a preference.

Diffuse 2 pounds of ground madder in 4 quarts of water, and after a
maceration of 10 minutes, strain and squeeze the grounds in a press.
Repeat this maceration, &c. twice upon the same portion of madder. It
will now have a fine rose colour. It must then be mixed with 5 or 6
pounds of water and half a pound of bruised alum, and heated upon a
water bath for 3 or 4 hours, with the addition of water, as it
evaporates, after which the whole must be thrown upon a filter cloth.
The liquor which passes is to be filtered through paper, and then
precipitated by carbonate of potash. If the potash be added in three
successive doses, three different lakes will be obtained, of
successively diminishing beauty. The precipitates must be washed till
the water comes off colourless.

_Blue lakes_ are hardly ever prepared, as indigo, prussian blue, cobalt
blue, and ultramarine, answer every purpose of blue pigments.

_Green lakes_ are made by a mixture of yellow lakes with blue pigments;
but chrome yellows mixed with blues produce almost all the requisite
shades of green.


LAMINABLE is said of a metal which may be extended by passing between
steel or hardened (chilled) cast-iron rollers.

For a description of metal rolling presses, see IRON and MINT; and

For a table of the relative laminability of metals, see DUCTILITY.


LAMIUM ALBUM, or the dead nettle, is said by Leuchs to afford in its
leaves a greenish-yellow dye. The L. purpureum dyes a reddish-grey with
salt of tin, and a greenish tint with iron liquor.


LAMPS differ so much in principle, form, and construction, as to render
their description impossible, as a general subject of manufacture. In
fact, the operations of the lampist, like those of the blacksmith,
cabinet-maker, cooper, coppersmith, tinman, turner, &c., belong to a
treatise upon handicraft trades. I shall here, however, introduce a
tabular view of the relative light and economy of the lamps most
generally known.

  +----------+----------------------------------+------+------+-------+
  |   Kind   |     Intensity of light during    | Mean |Con-  | Light |
  |    of    +----+-----+-----+-----+-----+-----+ of 7 |sump- | from  |
  |  Lamps.  |  1 |  2  |  3  |  4  |  5  |  6  |hours.|tion  |  100  |
  |          |hour|hours|hours|hours|hours|hours|      |per   | parts |
  |          |    |     |     |     |     |     |      |hour  |of oil.|
  |          |    |     |     |     |     |     |      |in    |       |
  |          |    |     |     |     |     |     |      |gram- |       |
  |          |    |     |     |     |     |     |      |mes.  |       |
  +----------+----+-----+-----+-----+-----+-----+------+------+-------+
  |Mechanical|    |     |     |     |     |     |      |      |       |
  |lamp of   |    |     |     |     |     |     |      |      |       |
  |Carcel    |    |     |     |     |     |     |100   |42    |  238  |
  |Fountain  |    |     |     |     |     |     |      |      |       |
  |lamp, and |    |     |     |     |     |     |      |      |       |
  |a chimney |    |     |     |     |     |     |      |      |       |
  |with flat |    |     |     |     |     |     |      |      |       |
  |wick      |100 |  98 |  98 |  97 |  96 |  96 |125   |11    |  113  |
  |Dome ar-  |    |     |     |     |     |     |      |      |       |
  |gand      |103 |  90 |  72 |  61 |  42 |  34 | 31   |26·714|  116  |
  |Sinumbra  |    |     |     |     |     |     |      |      |       |
  |lamp      |102 |  95 |  83 |  81 |  78 |  66 | 56   |37·145|  150  |
  |Do. with  |    |     |     |     |     |     |      |      |       |
  |fountain  |    |     |     |     |     |     |      |      |       |
  |above     |100 |  90 |  70 |  52 |  41 |  32 | 85   |43    |  197  |
  |Do. with  |    |     |     |     |     |     |      |      |       |
  |another   |    |     |     |     |     |     |      |      |       |
  |beak      |100 |  97 |  95 |  92 |  89 |  86 | 41   |18    |  227  |
  |Girard’s  |    |     |     |     |     |     |      |      |       |
  |hydro-    |    |     |     |     |     |     |      |      |       |
  |static    |    |     |     |     |     |     |      |      |       |
  |lamp      |101 |  96 |  84 |  81 |  76 |  70 | 63·66|34·714|  182  |
  |Thilo-    |    |     |     |     |     |     |      |      |       |
  |rier’s or |    |     |     |     |     |     |      |      |       |
  |Parker’s  |    |     |     |     |     |     |      |      |       |
  |do. lamp  |106 | 103 | 100 |  94 |  92 |  90 |107·66|51·143|  215  |
  +----------+----+-----+-----+-----+-----+-----+------+------+-------+

In the above table, for the purpose of comparing the successive degrees
of intensity, 100 represents the mean intensity of light during the
first hour. The quantity of oil consumed per hour is given in grammes,
of 15-1/2 grains each. The last column expresses the quantity of light
produced with a like consumption of oil, which was in all cases 100
grammes. See CANDLES.

The following table of M. Peclet is perhaps more instructive:--

  +------------+------+--------+-------------------+----------+--------+
  |  Nature    | In-  |Consump-|       Cost        | Fat pro- |Cost per|
  |  of the    |tensi-|tion per+---------+---------+ducing the| hour.  |
  |  light.    | ty.  |hour in |  per    |of light |   same   |        |
  |            |      |grammes.| kilogr. |per hour.|  light.  |        |
  +------------+------+--------+---------+---------+----------+--------+
  |            |      |        |_francs._| _cents._|_grammes._|_cents._|
  |Mechanical  |      |        |         |         |          |        |
  |lamp        |100   | 42     |   1·40  |   5·8   |   42     |  5·8   |
  |Flat-wick   |      |        |         |         |          |        |
  |mechan.  do.| 12·05| 11     |   1·40  |   1·5   |   88     | 12·3   |
  |Hemispheri- |      |        |         |         |          |        |
  |cal dome    |      |        |         |         |          |        |
  |lamp        | 31·0 | 26·714 |   1·40  |   3·7   |   86·16  | 12·0   |
  |Sinumbra    |      |        |         |         |          |        |
  |lamp        | 85   | 43     |   1·40  |   6·0   |   50·58  |  7·0   |
  |Do. with a  |      |        |         |         |          |        |
  |lateral     |      |        |         |         |          |        |
  |fountain or |      |        |         |         |          |        |
  |vase        | 41   | 18     |   1·40  |   2·5   |   43·90  |  6·1   |
  |Do. with a  |      |        |         |         |          |        |
  |fountain    |      |        |         |         |          |        |
  |above       | 90   | 43     |   1·40  |   6·0   |   47·77  |  6·6   |
  |Girard’s    |      |        |         |         |          |        |
  |hydrostatic |      |        |         |         |          |        |
  |lamp        | 63·66| 34·71  |   1·40  |   4·8   |   54·52  |  7·6   |
  |Thilorier’s |      |        |         |         |          |        |
  |or Parker’s |      |        |         |         |          |        |
  |do.         |107·66| 51·143 |   1·40  |   7·1   |   47·5   |  6·6   |
  |Candle, 6   |      |        |         |         |          |        |
  |in lb.      | 10·66|  8·51  |   1·40  |   1·2   |   70·35  |  9·8   |
  |Do. 8 in do.|  8·74|  7·51  |   1·40  |   1·0   |   85·92  | 12·0   |
  |Do. 6 with  |      |        |         |         |          |        |
  |smaller wick|  7·50|  7·42  |   2·40  |   1·7   |   98·93  | 23·7   |
  |Wax candle, |      |        |         |         |          |        |
  |5 in lb.    | 13·61|  8·71  |   7·60  |   5·7   |   64·04  | 48·6   |
  |Sperm       |      |        |         |         |          |        |
  |candle, do. | 14·40|  8·92  |   7·60  |   5·8   |   61·94  | 47·8   |
  |Stearine    |      |        |         |         |          |        |
  |candle, do. | 14·30|  9·35  |   6·00  |   5·5   |   65·24  | 37·1   |
  |Coal gas    |127   |136     |         |   5·0   |  107     |  3·9   |
  |            |      |  litres|         |         |    litres|        |
  |Oil gas     |127   |136 do. |         |   5·0   |   30     |  3·9   |
  +------------+------+--------+-------------------+----------+--------+

The light of the mechanical lamp is greatly over-rated relatively to
that of gas. The cost of the former is at least 5 times greater than of
the latter, in London.


LAMP OF DAVY consists of a common oil lamp, surmounted with a covered
cylinder of wire gauze, for transmitting light to the miner without
endangering the kindling of the atmosphere of fire-damp which may
surround him; because carburetted hydrogen, in passing through the
meshes of the cylindric cover, gets cooled by the conducting power of
the metallic gauze, below the point of its accension.

The apertures in the gauze should not be more than 1-20th of an inch
square. Since the fire-damp is not inflamed by ignited wire, the
thickness of the wire is not of importance, but wire from 1-40th to
1-60th of an inch in diameter is the most convenient.

[Illustration: 614]

The cage or cylinder should be made by double joinings, the gauze being
folded over in such a manner as to leave no apertures. When it is
cylindrical, it should not be more than two inches in diameter; because
in larger cylinders, the combustion of the fire-damp renders the top
inconveniently hot; a double top is always a proper precaution, fixed
1/2 or 3/4 of an inch above the first top. See _fig._ 614.

[Illustration: 615]

The gauze cylinder should be fastened to the lamp by a screw _b_, _fig._
615., of four or five turns, and fitted to the screw by a tight ring.
All joinings in the lamp should be made with hard solder; as the
security depends upon the circumstance, that no aperture exists in the
apparatus, larger than in the wire-gauze.

The parts of the lamp are,

1. The brass cistern _a_, _d_, _fig._ 615., which contains the oil. It
is pierced at one side of the centre with a vertical narrow tube, nearly
filled with a wire which is recurved above, at the level of the burner,
to trim the wick, by acting on the lower end of the wire _e_ with the
fingers. It is called the safety-trimmer.

2. The rim _b_ is the screw neck for fixing on the gauze cylinder, in
which the wire-gauze cover is fixed, and which is fastened to the
cistern by a screw fitted to _b_.

3. An aperture _c_ for supplying oil. It is fitted with a screw or a
cork, and communicates with the bottom of the cistern by a tube at _f_.
A central aperture for the wick.

4. The wire-gauze cylinder, _fig._ 614., which should not have less than
625 apertures to the square inch.

5. The second top, 3/4 of an inch above the first, surmounted by a brass
or copper plate, to which the ring of suspension may be fixed. It is
covered with a wire cap in the figure.

6. Four or six thick vertical wires, _g´ g´ g´ g´_, joining the cistern
below with the top plate, and serving as protecting pillars round the
cage. _g_ is a screw-pin to fix the cover, so that it shall not become
loosened by accident or carelessness. The oil-cistern _fig._ 615. is
drawn upon a larger scale than _fig._ 614., to show its minuter parts.

When the wire-gauze safe-lamp is lighted and introduced into an
atmosphere gradually mixed with fire-damp, the first effect of the
fire-damp is to increase the length and size of the flame. When the
inflammable gas forms so much as 1-12th of the volume of the air, the
cylinder becomes filled with a feeble blue flame, while the flame of the
wick appears burning brightly within the blue flame. The light of the
wick augments till the fire-damp increases to 1-6th or 1-5th, when it is
lost in the flame of the fire-damp, which in this case fills the
cylinder with a pretty strong light. As long as any _explosive_ mixture
of gas exists in contact with the lamp, so long it will give light; and
when it is extinguished, which happens whenever the foul air constitutes
so much as 1-3d of the volume of the atmosphere, the air is no longer
proper for respiration; for though animal life will continue where flame
is extinguished, yet it is always with suffering. By fixing a coil of
platinum wire above the wick, ignition may be maintained in the metal
when the lamp itself is extinguished; and from this ignited wire the
wick may be again rekindled, on carrying it into a less inflammable
atmosphere.

“We have frequently used the lamps where the explosive mixture was so
high as to heat the wire-gauze red-hot; but on examining a lamp which
has been in constant use for three months, and occasionally subjected to
this degree of heat, I cannot perceive that the gauze cylinder of iron
wire is at all impaired. I have not, however, thought it prudent, in our
present state of experience, to persist in using the lamps under such
circumstances, because I have observed, that in such situations the
particles of coal dust floating in the air, fire at the gas burning
within the cylinder, and fly off in small luminous sparks. This
appearance, I must confess, alarmed me in the first instance, but
experience soon proved that it was not dangerous.

“Besides the facilities afforded by this invention to the working of
coal-mines abounding in fire-damp, it has enabled the directors and
superintendents to ascertain, with the utmost precision and expedition,
both the presence, the quantity, and correct situation of the gas.
Instead of creeping inch by inch with a candle, as is usual, along the
galleries of a mine suspected to contain fire-damp, in order to
ascertain its presence, we walk firmly on with the safe-lamps, and, with
the utmost confidence, prove the actual state of the mine. By observing
attentively the several appearances upon the flame of the lamp, in an
examination of this kind, the cause of accidents which happened to the
most experienced and cautious miners is completely developed; and this
has hitherto been in a great measure matter of mere conjecture.

“It is not necessary that I should enlarge upon the national advantages
which must necessarily result from an invention calculated to prolong
our supply of mineral coal, because I think them obvious to every
reflecting mind; but I cannot conclude without expressing my highest
sentiments of admiration for those talents which have developed the
properties, and controlled the power, of one of the most dangerous
elements which human enterprise has hitherto had to encounter.”--See
Letter to Sir H. Davy, in Journal of Science, vol. i. p. 302., by John
Buddle, Esq., generally and justly esteemed one of the most scientific
coal-miners in the kingdom.

Mr. Buddle, in a letter dated 21st August, 1835, which is published in
Dr. Davy’s life of his brother Sir Humphrey, says;--

“In the evidence given in my last examination before a committee of the
House of Commons, I stated that after nearly twenty years’ experience of
‘the Davy’ with from 1000 to 1500 lamps in daily use, in all the variety
of circumstances incidental to coal mining, without a single accident
having happened which could be attributed to a defect in its principle,
or even in the rules for its practical application, as laid down by Sir
Humphrey--I maintained that ‘the Davy’ approximated perfection, as
nearly as any instrument of human invention could be expected to do. We
have ascertained distinctly that the late explosion did not happen in
that part of the mine where the Davys were used. They were all found in
a perfect state after the accident--many of them in the hands of the
dead bodies of the sufferers.”


LAMP-BLACK. See BLACK.


LAMPATES and LAMPIC ACID. When a spirit of wine lamp has its cotton wick
surmounted with a spiral coil of platinum wire, after lighting it for a
little, it may be blown out, without ceasing to burn the alcohol; for
the coil continues ignited, and a current of hot vapour continues to
rise, as long as the spirit lasts. This vapour was first condensed and
examined by Professor Daniell, who called it lampic acid. It has a
peculiar, strongly acid, burning taste, and a spec. grav. of 1·015. It
possesses in an eminent degree the property of reducing certain metallic
solutions; such as those of platinum, gold, and silver. The _lampates_
may be prepared by saturating the above acid with the alkaline and
earthy carbonates.


LAPIDARY, _Art of_. The art of the lapidary, or that of cutting,
polishing, and engraving gems, was known to the ancients, many of whom
have left admirable specimens of their skill. The Greeks were passionate
lovers of rings and engraved stones; and the most parsimonious among the
higher classes of the Cyrenians are said to have worn rings of the value
of ten minæ (about 30_l._ of our money.) By far the greater part of the
antique gems that have reached modern times, may be considered as so
many models for forming the taste of the student of the fine arts, and
for inspiring his mind with correct ideas of what is truly beautiful.
With the cutting of the diamond, however, the ancients were
unacquainted, and hence they wore it in its natural state. Even in the
middle ages, this art was still unknown; for the four large diamonds
which enrich the clasp of the imperial mantle of Charlemagne, as now
preserved in Paris, are uncut, octahedral crystals. But the art of
working diamonds was probably known in Hindostan and China, in very
remote periods. After Louis de Berghen’s discovery, in 1476, of
polishing two diamonds by their mutual attrition, all the finest
diamonds were sent to Holland to be cut and polished by the Dutch
artists, who long retained a superiority, now no longer admitted by the
lapidaries of London and Paris.

The operation of gem cutting is abridged by two methods; 1. by cleavage;
2. by cutting off slices with a fine wire, coated with diamond powder,
and fixed in the stock of a hand-saw. Diamond is the only precious stone
which is cut and polished with diamond powder, soaked with olive oil,
upon a mill plate of very soft steel.

Oriental rubies, sapphires, and topazes, are cut with diamond powder
soaked with olive oil, on a copper wheel. The facets thus formed are
afterwards polished on another copper wheel, with tripoli, tempered with
water.

Emeralds, hyacinths, amethysts, garnets, agates, and other softer
stones, are cut at a lead wheel, with emery and water; and are polished
on a tin wheel with tripoli and water, or, still better, on a zinc
wheel, with putty of tin and water.

The more tender precious stones, and even the pastes, are cut on a
mill-wheel of hard wood, with emery and water; and are polished with
tripoli and water, on another wheel of hard wood.

Since the lapidary employs always the same tools, whatever be the stone
which he cuts or polishes, and since the wheel discs alone vary, as also
the substance he uses with them, we shall describe, first of all, his
apparatus, and then the manipulations for diamond-cutting, which are
applicable to every species of stone.

[Illustration: 616]

The lapidary’s mill, or wheel, is shewn in perspective in _fig._ 616. It
consists of a strong frame made of oak carpentry, with tenon and
mortised joints, bound together with strong bolts and screw nuts. Its
form is a parallelopiped of from 8 to 9 feet long, by from 6 to 7 high;
and about 2 feet broad. These dimensions are large enough to contain two
cutting wheels alongside of each other, as represented in the figure.

Besides the two sole bars B B, we perceive in the breadth, 5 cross bars,
C, D, E, F, G. The two extreme bars C and G, are a part of the
frame-work, and serve to bind it. The two cross-bars D and F, carry each
in the middle of their length, a piece of wood as thick as themselves,
but only 4-1/2 inches long (see _fig._ 617.), joined solidly by mortises
and tenons with that cross bar, as well as with the one placed opposite
on the other parallel face. These two pieces are called _summers_
(lintels); the one placed at D is the upper; the one at F, the lower.

[Illustration: 617]

In _fig._ 617. this face is shewn inside, in order to explain how the
mill wheel is placed and supported. The same letters point out the same
objects, both in the preceding and the following figures.

In each of these _summers_ a square hole is cut out, exactly opposite to
the other; in which are adjusted by friction, a square piece of oak _a
a_, _fig._ 617., whose extremities are perforated with a conical hole,
which receives the two ends of the arbor H of the wheel I, and forms its
socket. This square bar is adjusted at a convenient height, by a double
wooden wedge _b b_.

The cross bar in the middle E supports the table _c c_, a strong plank
of oak. It is pierced with two large holes whose centres coincide with
the centre of the conical holes hollowed out at the end of the square
pins. These holes, of about 6 inches diameter each, are intended to let
the arbor pass freely through, bearing its respective wheel. (See one of
these holes at I, in _fig._ 621. below.)

[Illustration: 618 619]

Each wheel is composed of an iron arbor H, _fig._ 618., of a
grinding-wheel I, which differs in substance according to circumstances,
as already stated, and of the pulley J, furnished with several grooves
(see _fig._ 619.), which has a square fit upon the arbor. The arbor
carries a collet _d_, on which are 4 iron pegs or pins that enter into
the wheel to fasten it.

The wheel plate, of which the ground plan is shown at K, is hollowed out
towards its centre to half its thickness; when it is in its position on
the arbor, as indicated in _fig._ 619., a washer or ferrule of wrought
iron is put over it, and secured in its place by a double wedge. In
_fig._ 619. the wheel-plate is represented in section, that the
connection of the whole parts may be seen.

A board _g_ (see _fig._ 616. and _fig._ 624.), about 7-1/2 inches high,
is fixed to the part of the frame opposite to the side at which the
lapidary works, and it prevents the substances made use of in the
cutting and polishing, from being thrown to a distance by the
centrifugal force of the wheel-plate.

Behind this apparatus is mounted for each grinding-plate, a large wheel
L (see _fig._ 616.), similar to a cutler’s, but placed horizontally.
This wheel is grooved round its circumference to receive an endless cord
or band, which passes round one of the grooves of the pulley J, fixed
below the wheel-plate. Hence, on turning the fly-wheel L, the plate
revolves with a velocity relative to the velocity communicated to the
wheel L, and to the difference of diameter of the wheel L and the pulley
J. Each wheel L, is mounted on an iron arbor, with a crank (see M,
_fig._ 620.)

[Illustration: 620]

The lower pivot of that arbor _h_ is conical, and turns in a socket
fixed in the floor. The great wheel L rests on the collet _i_, furnished
with its 4 iron pins, for securing the connection. Above the wheel an
iron washer is laid, and the whole is fixed by a double wedge, which
enters into the mortise _l_, _fig._ 620.

[Illustration: 621]

[Illustration: 622]

_Fig._ 621. exhibits a ground-plan view of all this assemblage of parts,
to explain the structure of the machine. Every thing that stands above
the upper _summer-bar_ has been suppressed in this representation. Here
we see the table _c c_; the upper _summer_ _m_; the one wheel-plate _l_,
the other having been removed to shew that the endless cord does not
cross; the two large wheels L L, present in each machine, the crank bar
N, seen separate in _fig._ 622, which serves for turning the wheel L.
This bar is formed of 3 iron plates _n_, _o_; _p_, _q_; and _q_, _r_;
(_fig._ 622.) The first is bent round at the point _n_, to embrace the
stud _s_; the second _p q_, is of the same breadth and thickness as the
first; and the third, is adjusted to the latter with a hinge joint, at
the point _q_, where they are both turned into a circular form, to
embrace the crank M. When all these pieces are connected, they are fixed
at the proper lengths by the buckles or square rings _t t t_, which
embrace these pieces, as is shown in _fig._ 622.

[Illustration: 623]

The stud _s_, seen in _fig._ 622., is fixed to the point _v_ by a
wedge-key upon the arm P, represented separately, and in perspective, in
_fig._ 623. The labourer seizing the two upright pegs or handles _x x_;
by the alternate forward and backward motion of his arm, he communicates
the same motion to the crank rod, which transmits it to the crank of the
arbor M, and impresses on that arbor, and the wheel which it bears, a
rotatory movement.

[Illustration: 624]

_Fig._ 624. shows piece-meal and in perspective, a part of the
lapidary’s wheel-mill. There we see the table _c c_, the grind-plate I,
whose axis is kept in a vertical position by the two square plugs _a a_,
fixed into the two _summers_ by the wedges _b b_. On the two sides of
the wheel-plate we perceive an important instrument called a _dial_,
which serves to hold the stone during the cutting and polishing. This
instrument has received lately important ameliorations, to be described
in _fig._ 625. The lapidary holds this instrument in his hand, he rests
it upon the iron pins _u u_ fixed in the table, lest he should be
affected by the velocity of the revolving wheel-plate. He loads it
sometimes with weights _e_, _e_, to make it take better hold of the
grinding plate.

One of the most expert lapidaries of Geneva works by means of the
following improved mechanism, of his own invention, whereby he cuts and
polishes the facets with extreme regularity, converting it into a true
dial.

[Illustration: 625]

_Fig._ 625. shows this improvement. Each of the two jaws bears a large
conchoidal cavity, into which is fitted a brass ball, which carries on
its upper part a tube _e_, to whose extremity is fixed a dial-plate _f
f_, engraved with several concentric circles, divided into equal parts,
like the toothed-wheel cutting engine-plate, according to the number of
facets to be placed in each cutting range. The tube receives with
moderate friction the handle of the cement rod, which is fixed at the
proper point by a thumb-screw, not shown in the figure, being concealed
by the vertical limb _d_, about to be described.

A needle or index _g_, placed with a square fit on the tail of the
cement rod, marks by its point the divisions on the dial plate _f f_. On
the side _m n_ of the jaw A, there is fixed by two screws, a limb _d_,
forming a quadrant whose centre is supposed to be at the centre of the
ball. This quadrant is divided as usual into 90 degrees, whose highest
point is marked 0, and the lowest would mark about 70; for the remainder
of the arc down to 90 is concealed by the jaw. The two graduated plates
are used as follows:--

When the cement rod conceals zero or 0 of the limb, it is then vertical,
and serves to cut the table of the brilliant; or the point opposite to
it, and parallel to the table. On making it slope a little, 5 degrees
for example, all the facets will now lie in the same zone, provided that
the inclination be not allowed to vary. On turning round the cement rod
the index _g_ marks the divisions, so that by operating on the circle
with 16 divisions, stopping for some time at each, 16 facets will have
been formed, of perfect equality, and at equal distances, as soon as the
revolution is completed.

Diamonds are cut at the present day in only two modes; into a rose
diamond, and a brilliant. We shall therefore confine our attention to
these two forms.

The rose diamond is flat beneath, like all weak stones, while the upper
face rises into a dome, and is cut into facets. Most usually six facets
are put on the central region, which are in the form of triangles, and
unite at their summits; their bases abut upon another range of
triangles, which being set in an inverse position to the preceding,
present their bases to them, while their summits terminate at the sharp
margin of the stone. The latter triangles leave spaces between them
which are likewise cut each into two facets. By this distribution the
rose diamond is cut into 24 facets; the surface of the diamond being
divided into two portions, of which the upper is called the crown, and
that forming the contour, beneath the former, is called _dentelle_
(lace) by the French artists.

According to Mr. Jefferies, in his Treatise on Diamonds, the regular
rose diamond is formed by inscribing a regular octagon in the centre of
the table side of the stone, and bordering it by eight right-angled
triangles, the bases of which correspond with the sides of the octagon;
beyond these is a chain of 8 trapeziums, and another of 16 triangles.
The collet side also consists of a minute central octagon, from every
angle of which proceeds a ray to the edge of the girdle, forming the
whole surface into 8 trapeziums, each of which is again subdivided by a
salient angle (whose apex touches the girdle) into one irregular
pentagon and two triangles.

To fashion a rough diamond into a brilliant, the first step is to modify
the faces of the original octahedron, so that the plane formed by the
junction of the two pyramids shall be an exact square, and the axis of
the crystal precisely twice the length of one of the sides of the
square. The octahedron being thus rectified, a section is to be made
parallel to the common base or _girdle_, so as to cut off 5 eighteenths
of the whole height from the upper pyramid, and 1 eighteenth from the
lower one. The superior and larger plane thus produced is called the
_table_, and the inferior and smaller one is called the _collet_; in
this state it is termed a _complete square table diamond_. To convert it
into a brilliant, two triangular facets are placed on each side of the
table, thus changing it from a square to an octagon; a lozenge-shaped
facet is also placed at each of the four corners of the table, and
another lozenge extending lengthwise along the whole of each side of the
original square of the table, which with two triangular facets set on
the base of each lozenge, completes the whole number of facets on the
table side of the diamond; viz. 8 lozenges, and 24 triangles. On the
collet side are formed 4 irregular pentagons, alternating with as many
irregular lozenges radiating from the collet as a centre, and bordered
by 16 triangular facets adjoining the girdle. The brilliant being thus
completed, is set with the table side uppermost, and the collet side
implanted in the cavity made to receive the diamond. The brilliant is
always three times as thick as the rose diamond. In France, the
thickness of the brilliant is set off into two unequal portions; one
third is reserved for the upper part or table of the diamond, and the
remaining two thirds for the lower part or collet (_culasse_). The table
has eight planes, and its circumference is cut into facets, of which
some are triangles, and others lozenges. The collet is also cut into
facets called _pavillons_. It is of consequence that the pavillons lie
in the same order as the upper facets, and that they correspond to each
other, so that the symmetry be perfect, for otherwise the play of the
light would be false.

Although the rose-diamond projects bright beams of light in more
extensive proportion often than the brilliant, yet the latter shows an
incomparably greater play, from the difference of its cutting. In
executing this, there are formed 32 faces of different figures, and
inclined at different angles all round the table, on the upper side of
the stone. On the _collet_ (culasse) 24 other faces are made round a
small table, which converts the culasse into a truncated pyramid. These
24 facets, like the 32 above, are differently inclined and present
different figures. It is essential that the faces of the top and the
bottom correspond together in sufficiently exact proportions to multiply
the reflections and refractions, so as to produce the colours of the
prismatic spectrum.

The other precious stones, as well as their artificial imitations,
called _pastes_, are cut in the same fashion as the brilliant; the only
difference consists in the matter constituting the wheel plates, and the
grinding and polishing powders, as already stated.

[Illustration: 626]

In cutting the stones, they are mounted on the cement-rod B, _fig._
626., whose stem is set upright in a socket placed in the middle of a
sole piece at A, which receives the stem of the cement-rod. The head of
the rod fills the cup of A. A melted alloy of tin and lead is poured
into the head of the cement-rod, into the middle of which the stone is
immediately plunged; and whenever the solder has become solid, a portion
of it is pared off from the top of the diamond, to give the pyramidal
form shown in the figure at B.

[Illustration: 627]

There is an instrument employed by the steel polishers for pieces of
clock work, and by the manufacturers of watch-glasses for polishing
their edges. It consists of a solid oaken table, _fig._ 627. The top is
perforated with two holes, one for passing through the pulley and the
arbor of the wheel-plate B, made either of lead or of hard wood,
according to circumstances; and the other C for receiving the upper part
of the arbor of the large pulley D. The upper pulley of the wheel-plate
is supported by an iron prop E, fixed to the table by two wooden screws.
The inferior pivots of the two pieces are supported by screw-sockets,
working in an iron screw-nut sunk into the summer-bar F. The legs of the
table are made longer or shorter, according as the workman chooses to
stand or sit at his employment. Emery with oil is used for grinding
down, and tin-putty or colcothar for polishing. The workman lays the
piece on the flat of the wheel-plate with one hand, and presses it down
with a lump of cork, while he turns round the handle with the other
hand.

The _Sapphire_, _Ruby_, _Oriental Amethyst_, _Oriental Emerald_, and
_Oriental Topaz_, are gems next in value and hardness to diamond; and
they all consist of nearly pure alumina or clay, with a minute portion
of iron as the colouring matter. The following analyses show the
affinity in composition of the most precious bodies with others in
little relative estimation.

  +---------------+---------+---------------+------+
  |               |Sapphire.|Corundum Stone.|Emery.|
  |               +---------+---------------+------+
  |Alumina or clay|   98·5  |     89·50     | 86·0 |
  |Silica         |    0·0  |      5·50     |  3·0 |
  |Oxide of iron  |    1·0  |      1·25     |  4·0 |
  |Lime           |    0·5  |      0·00     |  0·0 |
  |               +---------+---------------+------+
  |               |  100·0  |     96·25     | 93·0 |
  +---------------+---------+---------------+------+

_Salamstone_ is a variety which consists of small transparent crystals,
generally six-sided prisms, of pale reddish and bluish colours. The
corundum of Battagammana is frequently found in large six-sided prisms:
it is commonly of a brown colour, whence it is called by the natives
_curundu gallé_, cinnamon stone. The hair-brown and reddish-brown
crystals are called adamantine spar. Sapphire and salamstone are chiefly
met with in secondary repositories, as in the sand of rivers &c.,
accompanied by crystals and grains of octahedral iron-ore and of several
species of gems. Corundum is found in imbedded crystals in a rock,
consisting of indianite. Adamantine spar occurs in a sort of granite.

The finest varieties of sapphire come from Pegu, where they occur in the
Capelan mountains near Syrian. Some have been found also at Hohenstein
in Saxony, Bilin in Bohemia, Puy in France, and in several other
countries. The red variety, the ruby, is most highly valued. Its colour
is between a bright scarlet and crimson. A perfect ruby above 3-1/2
carats is more valuable than a diamond of the same weight. If it weigh
one carat, it is worth 10 guineas; 2 carats, 40 guineas; 3 carats, 150
guineas; 6 carats, above 1000 guineas. A deep coloured ruby, exceeding
20 carats in weight, is generally called a carbuncle; of which 108 were
said to be in the throne of the Great Mogul, weighing from 100 to 200
carats each; but this statement is probably incorrect. The largest
oriental ruby known to be in the world, was brought from China to Prince
Gargarin, governor of Siberia. It came afterwards into the possession of
Prince Menzikoff, and constitutes now a jewel in the imperial crown of
Russia.

A good blue sapphire of 10 carats is valued at 50 guineas. If it weighs
20 carats, its value is 200 guineas; but under 10 carats, the price may
be estimated by multiplying the square of its weight in carats into half
a guinea; thus, one of 4 carats would be worth 4² × 1/2 G. = 8 guineas.
It has been said that the blue sapphire is superior in hardness to the
red, but this is probably a mistake arising from confounding the
corundum ruby with the spinelle ruby. A sapphire of a barbel blue
colour, weighing 6 carats, was disposed of in Paris by public sale for
70_l._ sterling; and another of an indigo blue, weighing 6 carats and 3
grains, brought 60_l._; both of which sums much exceed what the
preceding rule assigns, from which we may perceive how far fancy may go
in such matters. The sapphire of Brasil is merely a blue tourmaline, as
its specific gravity and inferior hardness show. White sapphires are
sometimes so pure, that when properly cut and polished they have been
passed for diamonds.

The yellow and green sapphires are much prized under the names of
Oriental topaz and emerald. The specimens which exhibit all these
colours associated in one stone are highly valued, as they prove the
mineralogical identity of these varieties.

Besides these shades of colour, sapphires often emit a beautiful play of
colours, or _chatoiement_, when held in different positions relative to
the eye or incident light; and some likewise present star-like
radiations, whence they are called star-stones or _asterias_; sending
forth 6 or even 12 rays, that change their place with the position of
the stone. This property so remarkable in certain blue sapphires, is not
however peculiar to these gems. It seems to belong to transparent
minerals which have a rhomboid for their nucleus, and arises from the
combination of certain circumstances in their cutting and structure.
Lapidaries often expose the light-blue variety of sapphire to the action
of fire, in order to render it white and more brilliant; but with regard
to those found at Expailly in France, fire deepens their colour.

3. _Chrysoberyl_, called by Haüy Cymophane, and by others Prismatic
corundum, ranks next in hardness to sapphire, being 8·5 on the same
scale of estimation. Its specific gravity is 3·754. It usually occurs in
rounded pieces about the size of a pea, but it is also found
crystallised in many forms, of which 8-sided prisms with 8-sided summits
are perhaps the most frequent. Lustre vitreous; colour asparagus green,
passing into greenish-white and olive-green. It shows a bluish
opalescence, a light undulating as it were in the stone, when viewed in
certain directions; which property constitutes its chief attraction to
the jeweller. When polished, it has been sometimes mistaken for a yellow
diamond; and from its hardness and lustre is considerably valued. Good
specimens of it are very rare. It has been found only in the alluvial
deposits of rivers, along with other species of gems. Thus it occurs in
Brasil, along with diamonds and prismatic topaz; also in Ceylon. Its
constituents are, alumina 68·66; glucina 16·00; silica 6·00; protoxide
of iron 4·7; oxide of titanium 2·66; moisture 0·66, according to
Seybert’s analysis of a specimen from Brasil. It is difficultly but
perfectly fusible before the blowpipe, with borax and salt of
phosphorus. In composition it differs entirely from sapphire, or the
rhombohedral corundum.

4. _Spinelle Ruby_, called Dodecahedral corundum by some mineralogists,
and Balas ruby by lapidaries. Its hardness is 8. Specific gravity 3·523.
Its fundamental form is the hexahedron, but it occurs crystallized in
many secondary forms: octahedrons, tetrahedrons and rhombohedrons.
Fracture conchoidal; lustre vitreous; colour red, passing into blue and
green, yellow, brown and black; and sometimes it is nearly white. Red
spinelle consists of, alumina 74·5; silica 15·5; magnesia 8·25; oxide of
iron 1·5; lime 0·75. Vauquelin discovered 6·18 _per cent._ of chromic
acid in the red spinelle. The red varieties exposed to heat, become
black and opaque; on cooling they appear first green, then almost
colourless, but at last resume their red colour. _Pleonaste_ is a
variety which yields a deep green globule with borax.

Crystals of spinelle from Ceylon have been observed imbedded in
limestone, mixed with mica, or in rocks containing adularia, which seem
to have belonged to a primitive district. Other varieties like the
pleonaste occur in the drusy cavities of rocks ejected by Vesuvius.
Crystals of it are often found in diluvial and alluvial sand and gravel,
along with true sapphires, pyramidal zircon, and other gems, as also
with octahedral iron ore, in Ceylon. Blue and pearl-gray varieties occur
in Südermannland in Sweden, imbedded in granular limestone. Pleonaste is
met with also in the diluvial sands of Ceylon. Clear and finely coloured
specimens of spinelle are highly prized as ornamental stones. When the
weight of a good spinelle exceeds 4 carats, it is said to be valued at
half the price of a diamond of the same weight. M. Brard has seen one at
Paris, which weighed 215 grains.

5. _Zircon_ or _Hyacinth_. Its fundamental form is an isosceles 4-sided
pyramid; and the secondary forms have all a pyramidal character.
Fracture conchoidal, uneven; lustre more or less perfectly adamantine;
colours, red, brown, yellow, gray, green, white; which with the
exception of some red tints, are not bright. Hardness 7·5. Specific
gravity 4·5. Zircon and hyacinth consist, according to Klaproth, of
almost exactly the same constituents; namely, zirconia 70; silica 25;
oxide of iron 5. In the white zirconia there is less iron and more
silica. Before the blowpipe the hyacinth loses its colour, but does not
melt. The brighter zircons are often worked up into a _brilliant_ form,
for ornamenting watch cases. As a gem, hyacinth has no high value. It
has been often confounded with other stones, but its very great specific
gravity makes it to be readily recognized.

6. _Topaz._ The fundamental form is a scalene 4-sided pyramid; but the
secondary forms have a prismatic character; and are frequently observed
in oblique 4-sided prisms, acuminated by 4 planes. The lateral planes of
the prism are longitudinally striated. Fracture conchoidal, uneven;
lustre vitreous; colours, white, yellow, green, blue, generally of pale
shades. Hardness 8; specific gravity 3·5. Prismatic topaz consists,
according to Berzelius, of alumina 57·45; silica 34·24; fluoric acid
7·75. In a strong heat the faces of crystallization, but not those of
cleavage, are covered with small blisters, which however immediately
crack. With borax, it melts slowly into a transparent glass. Its powder
colours the tincture of violets green. Those crystals which possess
different faces of crystallization on opposite ends, acquire the
opposite electricities on being heated. By friction, it acquires
positive electricity.

Most perfect crystals of topaz have been found in Siberia, of green,
blue, and white colours, along with beryl, in the Uralian and Altai
mountains, as also in Kamschatka; in Brazil, where they generally occur
in loose crystals, and pebble forms of bright yellow colours; and in
Mucla in Asia Minor, in pale straw-yellow regular crystals. They are
also met with in the granitic detritus of Cairngorm in Aberdeenshire.
The blue varieties are absurdly called _oriental aquamarine_ by
lapidaries. If exposed to heat, the Saxon topaz loses its colour and
becomes white; the deep yellow Brazilian varieties assume a pale pink
hue; and are then sometimes mistaken for spinelle, to which, however,
they are somewhat inferior in hardness. Topaz is also distinguishable by
its double refractive property. Tavernier mentions a topaz, in the
possession of the Great Mogul, which weighed 157 carats, and cost
20,000_l._ sterling. There is a specimen in the museum of natural
history at Paris which weighs 4 ounces 2 gros.

Topazes are not scarce enough to be much valued by the lapidary.

7. _Emerald_ and _Beryl_, are described in their alphabetical places.
Emerald loses its lustre by candle-light; but as it appears to most
advantage when in the company of diamonds, it is frequently surrounded
with brilliants, and occasionally with pearls. Beryl is the aqua-marine
of the jewellers, and has very little estimation among lapidaries.

8. _Garnet._ See this stone in its alphabetical place.

9. _Chrysolite_, called _Peridot_ by Haüy; probably the topaz of the
ancients, as our topaz was their chrysolite. It is the softest of the
precious stones, being scratched by quartz and the file. It refracts
double.

10. _Quartz_, including, as sub-species, _Amethyst_, _Rock-crystal_,
_Rose-quartz_, _Prase_ or _Chrysoprase_, and several varieties of
calcedony, as _Cat’s eye_, _Plasma_, _Chrysoprase_, _Onyx_, _Sardonyx_,
&c. Lustre vitreous, inclining sometimes to resinous; colours, very
various; fracture conchoidal; hardness, 7; specific gravity, 2·69.

11. _Opal_, or uncleavable quartz. Fracture, conchoidal; lustre,
vitreous or resinous; colours, white, yellow, red, brown, green, gray.
Lively play of light; hardness, 5·5 to 6·5; specific gravity, 2·091. It
occurs in small kidney-shaped and stalactitic shapes, and large tuberose
concretions. The phenomena of the play of colours in precious opal has
not been satisfactorily explained. It seems to be connected with the
regular structure of the mineral. Hydrophane, or oculis mundi, is a
variety of opal without transparency, but acquiring it when immersed in
water, or in any transparent fluid. Precious opal was found by Klaproth
to consist of silica, 90; water, 10; which is a very curious
combination. Hungary has been long the only locality of precious opal,
where it occurs near Caschau, along with common and semi-opal, in a kind
of porphyry. Fine varieties have, however, been lately discovered in the
Faroe islands; and most beautiful ones, sometimes quite transparent,
near Gracias a Dios, in the province of Honduras, America. The red and
yellow bright coloured varieties of fire-opal are found near Zimapan, in
Mexico. Precious opal, when fashioned for a gem, is generally cut with a
convex surface; and if large, pure, and exhibiting a bright play of
colours, is of considerable value. In modern times, fine opals of
moderate bulk have been frequently sold at the price of diamonds of
equal size; the Turks being particularly fond of them. The estimation in
which opal was held by the ancients is hardly credible. They called it
Paideros, or Child beautiful as love. Nonius, the Roman senator,
preferred banishment to parting with his favourite opal, which was
coveted by Mark Antony. Opal which appears quite red when held against
the light, is called _girasol_ by the French; a name also given to the
sapphire or corundum asterias or star-stone.

12. _Turquois_, or _Calaite_. Mineral turquois, occurs massive;
fine-grained impalpable; fracture conchoidal; colour, between a blue and
a green, soft, and rather bright; opaque; hardness, 6; spec. grav. 2·83
to 3·0. Its constituents are, alumina, 73; oxide of copper, 4·5; oxide
of iron, 4; water, 18; according to Dr. John. But by Berzelius, it
consists of phosphate of alumina and lime, silica, oxides of copper and
iron, with a little water. It has been found only in the neighbourhood
of Nichabour in the Khorassan, in Persia; and is very highly prized as
an ornamental stone in that country. There is a totally different kind
of turquois, called _bone turquois_, which seems to be phosphate of lime
coloured with oxide of copper. When the oriental stone is cut and
polished, it forms a pleasing gem of inferior value. _Malachite_, or
mountain green, a compact carbonate of copper, has been substituted
sometimes for turquois, but their shades are different. Malachite yields
a green streak, and turquois a white one.

13. _Lapis lazuli_, is of little value, on account of its softness.


LEAD. (_Plomb_, Fr.; _Blei_, Germ.) This is one of the metals most
antiently known, being mentioned in the books of Moses. It has a gray
blue colour, with a bright metallic lustre when newly cut, but it
becomes soon tarnished and earthy looking in the air. Its texture is
close, without perceptible cleavage or appearance of structure; the
specific gravity of common lead is 11·352; but of the pure metal, from
11·38 to 11·44. It is very malleable and ductile, but soft and destitute
of elasticity; fusible at 612° Fahr., by Crighton, at 634° by Kupfer,
and crystallizable on cooling, into octahedrons implanted into each
other so as to form an assemblage of four-sided pyramids.

There are four oxides of lead. 1. The suboxide of a grayish blue colour,
which forms a kind of crust upon a plate of lead long exposed to the
air. It is procured in a perfect state by calcining oxalate of lead in a
retort; the dark gray powder which remains is the pure suboxide. 2. The
protoxide is obtained by exposing melted lead to the atmosphere, or,
more readily, by expelling the acid from the nitrate of lead by heat in
a platinum crucible. It is yellow, and was at one time prepared as a
pigment by calcining lead; but is now superseded by the chromate of this
metal. Litharge is merely this oxide in the form of small spangles, from
having undergone fusion; it is more or less contaminated with iron,
copper, and sometimes a little silver. It contains likewise some
carbonic acid. The above oxide consists of 104 of metal, and 8 of
oxygen, its prime equivalent being 112, upon the hydrogen scale; and it
is the base of all the salts of lead. 3. The plumbeous suroxide of
Berzelius, the sesquioxide of some British chemists, is the well-known
pigment called RED LEAD or _minium_. It consists of 100 parts of metal
and 10 of oxygen. 4. The plumbic suroxide of Berzelius, or the peroxide
of the British chemists, is obtained by putting red lead in chlorine
water, or in dilute nitric acid. It is of a dark brown, almost black
colour, which gives out oxygen when heated, and becomes yellow oxide. It
kindles sulphur when triturated with it. This oxide is used by the
analytical chemist to separate, by condensation, the sulphurous acid
existing in a gaseous mixture.

Among the ores of lead some have a metallic aspect; are black in
substance, as well as when pulverized; others have a stony appearance,
and are variously coloured, with usually a vitreous or greasy lustre.
The specific gravity of the latter ores is always less than 5. The whole
of them, excepting the chloride, become more or less speedily black,
with sulphuretted hydrogen or with hydrosulphurets; and are easily
reduced to the metallic state upon charcoal, with a flux of carbonate of
soda, after they have been properly roasted. They diffuse a whitish or
yellowish powder over the charcoal, which, according to the manner in
which the flame of the blowpipe is directed upon it, becomes yellow or
red; thus indicating the two characteristic colours of the oxides of
lead.

We shall not enter here into the controversy concerning the existence of
native lead, which has been handled at length by M. Brongniart in the
_Dictionnaire des Sciences Naturelles_, article _Plomb, Mineralogie_.

The lead ores most interesting to the arts are:--

1. _Galena_, sulphuret of lead. This ore has the metallic lustre of lead
with a crystalline structure derivable from the cube. When heated
cautiously at the blowpipe it is decomposed, the sulphur flies off, and
the lead is left alone in fusion; but if the heat be continued, the
coloured surface of the charcoal indicates the conversion of the lead
into its oxides. Galena is a compound of lead and sulphur, in equivalent
proportions, and therefore consists, in 100 parts, of 86-2/3 of metal,
and 13-1/3 of sulphur, with which numbers the analysis of the galena of
Clausthal by Westrumb exactly agrees. Its specific gravity, when pure,
is 7·56. Its colour is blackish gray, without any shade of red, and its
powder is black; characters which distinguish it from _blende_ or
sulphuret of zinc. Its structure in mass is lamellar, passing sometimes
into the fibrous or granular, and even compact. It is brittle. The
_specular_ galena, so called from its brightly polished aspect, is
remarkable for forming the _slickensides_ of Derbyshire--thin seams,
which explode with a loud noise when accidentally scratched in the mine.

The argentiferous galena has in general all the external characters of
pure galena. The proportions of silver vary from one-fifth part of the
whole, as at Tarnowitz, in Silesia, to three parts in ten thousand, as
in the ore called by the German miners Weisgültigerz; but it must be
observed, that whenever this lead ore contains above 5 per cent. of
silver, several other metals are associated with it. The mean proportion
of silver in galena, or that which makes it be considered practically as
an argentiferous ore, because the silver may be profitably extracted, is
about two parts in the thousand. See SILVER. The above rich silver ores
were first observed in the Freyberg mines, called Himmelsfürst and
Beschertglück, combined with sulphuret of antimony; but they have been
noticed since in the Hartz, in Mexico, and several other places.

The antimonial galena (_Bournonite_) exhales at the blowpipe the odour
peculiar to antimony, and coats the charcoal with a powder partly white
and partly red. It usually contains some arsenic.

2. The _Seleniuret of lead_, resembles galena, but its tint is bluer.
Its chemical characters are the only ones which can be depended on for
distinguishing it. At the blowpipe, it exhales a very perceptible smell
of putrid radishes. Nitric acid liberates the selenium. When heated in a
tube, oxide of selenium of a carmine red rises along with selenic acid,
white and deliquescent. The specific gravity of this ore varies from 6·8
to 7·69.

3. _Native minium_ or _red lead_, has an earthy aspect, of a lively and
nearly pure red colour, but sometimes inclining to orange. It occurs
pulverulent, and also compact, with a fracture somewhat lamellar. When
heated at the blowpipe upon charcoal, it is readily reduced to metallic
lead. Its specific gravity varies from 4·6 to 8·9. This ore is rare.

4. _Plomb-gomme._ This lead ore, as singular in appearance as in
composition, is of a dirty brownish or orange-yellow, and occurs under
the form of globular, or gum-like concretions. It has also the lustre
and translucency of gum; with somewhat of a pearly aspect at times. It
is harder than fluor spar. It consists of oxide of lead, 40; alumina,
37; water, 18·8; foreign matters and loss, 4·06; in 100. Hitherto it has
been found only at Huelgoët, near Poullaouen, in Brittany, covering with
its tears or small concretions the ores of white lead and galena which
compose the veins of that lead mine.

5. _White lead, carbonate of lead._ This ore in its purest state, is
colourless and transparent like glass, with an adamantine lustre. It may
be recognized by the following characters:--

Its specific gravity is from 6 to 6·7; it dissolves with more or less
ease, and with effervescence, in nitric acid; becomes immediately black
by the action of sulphuretted hydrogen, and melts on charcoal before the
blowpipe into a button of lead. According to Klaproth, the carbonate of
Leadhills contains 82 parts of oxide of lead, and 16 of carbonic acid,
in 98 parts. This mineral is tender, scarcely scratches calc-spar, and
breaks easily with a waved conchoidal fracture. It possesses the double
refracting property in a very high degree; the double image being very
visible on looking through the flat faces of the prismatic crystals. Its
crystalline forms are very numerous, and are referrible to the
octahedron, and the pyramidal prism.

6. _Vitreous lead_, or _sulphate of lead_. This mineral closely
resembles carbonate of lead; so that the external characters are
inadequate to distinguish the two. But the following are sufficient.
When pure, it has the same transparency and lustre. It does not
effervesce with nitric acid; it is but feebly blackened by sulphuretted
hydrogen; it first decrepitates and then melts before the blowpipe into
a transparent glass, which becomes milky as it cools. By the combined
action of heat and charcoal, it passes first into a red pulverulent
oxide, and then into metallic lead. It consists, according to Klaproth,
of 71 oxide of lead, 25 sulphuric acid, 2 water, and 1 iron. That
specimen was from Anglesea; the Wanlockhead mineral is free from iron.
The prevailing form of crystallization is the rectangular octahedron,
whose angles and edges are variously modified. The sulphato-carbonate,
and sulphato tri-carbonate of lead, now called _Leadhillite_, are rare
minerals which belong to this head.

7. _Phosphate of lead._--This, like all the combinations of lead with an
acid, exhibits no metallic lustre, but a variety of colours. Before the
blowpipe, upon charcoal, it melts into a globule externally crystalline,
which, by a continuance of the heat, with the addition of iron and
boracic acid, affords metallic lead. Its constituents are 80 oxide of
lead, 18 phosphoric acid, and 1·6 muriatic acid, according to Klaproth’s
analysis of the mineral from Wanlockhead. The constant presence of
muriatic acid in the various specimens examined is a remarkable
circumstance. The crystalline forms are derived from an obtuse rhomboid.
Phosphate of lead is a little harder than white lead; it is easily
scratched, and its powder is always gray. Its specific gravity is 6·9.
It has a vitreous lustre, somewhat adamantine. Its lamellar texture is
not very distinct; its fracture is wavy, and it is easily frangible. The
phosphoric and arsenic acids being, according to M. Mitscherlich,
isomorphous bodies, may replace each other in chemical combinations in
every proportion, so that the phosphate of lead may include any
proportion, from the smallest fraction of arsenic acid, to the smallest
fraction of phosphoric acid, thus graduating indefinitely into arseniate
of lead. The yellowish variety indicates, for the most part, the
presence of arsenic acid.

8. _Muriate of lead._ _Horn-lead_, or _murio-carbonate_.--This ore has a
pale yellow colour, is reducible to metallic lead by the agency of soda,
and is not altered by the hydrosulphurets. At the blowpipe it melts
first into a pale yellow transparent globule, with salt of phosphorus
and oxide of copper; and it manifests the presence of muriatic acid by a
bluish flame. It is fragile, tender, softer than carbonate of lead, and
is sometimes almost colourless, with an adamantine lustre. Spec. grav.
606. Its constituents, according to Berzelius, are, lead, 25·84; oxide
of lead, 57·07; carbonate of lead, 6·25; chlorine, 8·84; silica, 1·46;
water, 0·54; in 100 parts. The carbonate is an accidental ingredient,
not being in equivalent proportion. Klaproth found chlorine, 13·67;
lead, 39·98; oxide of lead, 22·57; carbonate of lead, 23·78.

9. _Arseniate of lead._--Its colour of a pretty pure yellow, bordering
slightly on the greenish, and its property of exhaling by the joint
action of fire and charcoal a very distinct arsenical odour, are the
only characters which distinguish this ore from the phosphate of lead.
The form of the arseniate of lead when it is crystallized, is a prism
with six faces, of the same dimensions as that of phosphate of lead.
When pure, it is reducible upon charcoal, before the blowpipe, into
metallic lead, with the copious exhalation of arsenical fumes; but only
in part, and leaving a crystalline globule, when it contains any
phosphate of lead. The arseniate of lead is tender, friable, sometimes
even pulverulent, and of specific gravity 5·04. That of
Johann-Georgenstadt consists, according to Rose, of oxide of lead 77·5;
arsenic acid 12·5; phosphoric acid 7·5, and muriatic acid 1·5.

10. _Red lead_, or _Chromate of lead_.--This mineral is too rare to
require consideration in the present work.

11. _Plomb vauquelinite. Chromate of lead and copper._

12. _Yellow lead. Molybdate of lead._

13. _Tungstate of lead._

Having thus enumerated the several species of lead ore, we may remark,
that galena is the only one which occurs in sufficiently great masses to
become the object of mining and metallurgy. This mineral is found in
small quantity among the crystalline primitive rocks, as granite. It is
however among the oldest talc-schists and clay slates, that it usually
occurs. But galena is much more abundant among the transition rocks,
being its principal locality, where it exists in interrupted beds,
masses, and more rarely in veins. The blackish transition limestone is
of all rocks that which contains most galena; as at Pierreville in
Normandy; at Clausthal, Zellerfeldt, and most mines of the Harz; at
Fahlun, in Sweden; in Derbyshire and Northumberland, &c. In the
transition graywacke of the south of Scotland, the galena mines of
Leadhills occur. The galena of the primitive formations contains more
silver than that of the calcareous.

The principal lead mines at present worked in the world, are the
following: 1. Poullaouen and Huelgoët near Carhaix in France, department
of Finisterre, being veins of galena, which traverse a clay slate
resting upon granite. They have been known for upwards of three
centuries; the workings penetrate to a depth of upwards of 300 yards,
and in 1816 furnished 500 tons of lead per annum, out of which 1034
pounds avoirdupois of silver were extracted. 2. At Villeforte and
Viallaz, department of the Lozère, are galena mines said to produce 100
tons of lead _per annum_, with 400 kilogrammes of silver (880 libs.
avoird.). 3. At Pezey and Macot, to the east of Moutiers in Savoy, a
galena mine exists in talc-schist, which has produced annually 200 tons
of lead, and about 600 kilogrammes of silver (1320 libs avoird.). 4. The
mine of Vedrin, near Namur in the Low Countries, is opened upon a vein
of galena, traversing compact limestone of a transition district; it has
furnished 200 tons of lead, from which 385 pounds avoird. of silver were
extracted. 5. In Saxony the galena mines are so rich in silver as to
make the lead be almost overlooked. They are enumerated under silver
ores. 6. The lead mines of the Harz, have been likewise considered as
silver ores. 7. Those of Bleyberg in the Eifel are in the same
predicament. 8. The galena mines of Bleyberg and Villach in Carinthia,
in compact limestone. 9. In Bohemia, to the south-west of Prague. 10.
The mines of Joachimsthal, and Bleystadt, on the southern slope of the
Erzgebirge, produce argentiferous galena. 11. There are numerous lead
mines in Spain, the most important being in the granite hills of
Linarès, upon the southern slope of the Sierra Morena, and in the
district of the small town of Canjagar. Sometimes enormous masses of
galena are extracted from the mines of Linarès. There are also mines of
galena in Catalonia, Grenada, Murcia, and Almeria, the ore of the last
locality being generally poor in silver. 12. The lead mines of Sweden
are very argentiferous, and worked chiefly with a view to the silver.
13. The lead mines of Daouria are numerous and rich, lying in a
transition limestone, which rests on primitive rocks; their lead is
neglected on account of the silver.

14. Of all the countries in the world, Great Britain is that which
annually produces the greatest quantity of lead. According to M.
Villefosse, in his _Richesse Minerale_, published in 1810, we had
furnished every year 12,500 tons of lead, whilst all the rest of Europe
taken together, did not produce so much; but from more recent documents,
that estimate seems to have been too low. Mr. Taylor has rated the total
product of the United Kingdom _per annum_ at 31,900 tons, a quantity
fully 2-1/2 times greater than the estimate of Villefosse (see Conybeare
and Phillips’ Geology, p. 354). Mr. Taylor distributes this product
among the different districts as follows:--

                                                               Tons.
  Wales, (Flintshire and Denbighshire)                         7,500
  Scotland, (in transition graywacke)                          2,800
  Durham, Cumberland, and Yorkshire, (in carboniferous lime)  19,000
  Derbyshire, (probably in carboniferous lime)                 1,000
  Shropshire                                                     800
  Devon and Cornwall, (transition and primitive rocks)           800
                                                              ------
  Total                                                       31,900

We thus see that Cumberland, and the adjacent parts of the counties of
Durham and York, furnish of themselves nearly three-fifths of the total
product. Derbyshire was formerly much more productive. In Cornwall and
Devonshire, the lead ore is found in veins in _killas_, a clay-slate
passing into greywacke. In North Wales and the adjacent counties, as
well as in Cumberland and Derbyshire, the lead occurs in the
carboniferous limestone.

The English lead-miners distinguish three different kinds of deposits of
lead ore; _rake-veins_, _pipe-veins_, and _flat-veins_. The English word
vein corresponds to the French term _filon_; but miners make use of it
indifferently in England and France, to indicate all the deposits of
this ore, adding an epithet to distinguish the different forms; thus,
_rake veins_ are true veins in the geological acceptation of the word
vein; _pipe-veins_ are masses usually very narrow, and of oblong shape,
most frequently parallel to the plane of the rocky strata; and
_flat-veins_ are small beds of ores interposed in the middle of these
strata.

_Rake-veins_ are the most common form in which lead ore occurs in
Cumberland. They are in general narrower in the sandstone which covers
the limestone, than in the calcareous beds. A thickness of less than a
foot in the former, becomes suddenly 3 or 4 feet in the latter; in the
rich vein of Hudgillburn, the thickness is 17 feet in the _Great
limestone_, while it does not exceed 3 feet in the overlying _Watersill_
or sandstone. This influence exercised on the veins by the nature of the
enclosing rock, is instructive; it determines at the same time almost
uniformly their richness in lead ore, an observation similar to what has
been made in other countries, especially in the veins of Kongsberg in
Norway. The Cumberland veins are constantly richer, the more powerful
they are, in the portions which traverse the calcareous rocks, than in
the beds of sandstone, and more particularly the schistose rocks. It is
rare in the rock called _plate_ (a solid slaty clay) for the vein to
include any ore; it is commonly filled with a species of potter’s earth.
The upper calcareous beds are also in general more productive than the
lower ones. In most of these mines, the veins were not worked till
lately below the fifth calcareous bed (the four-fathom limestone), which
is 307 yards beneath the millstone-grit; and as the first limestone
stratum is 108 yards beneath it, it follows that the thickness of the
part of the ground where the veins are rich in lead does not in general
exceed 200 yards. It appears however that veins have been mined in the
neighbourhood of Alston Moor, downwards to the eleventh calcareous
stratum, or Tyne bottom limestone, which is 418 yards under the
millstone-grit of the coal formation, immediately above the whin-sill;
and that they have been followed above the first limestone stratum, as
high as the grindstone sill, which is only 83 yards below the same
stratum of millstone-grit; so that in the total thickness of the
plumbiferous formation there is more than 336 yards. It has been
asserted that lead veins have been traced even further down, into the
_Memerby_ scar limestone; but they have not been mined.

The greatest enrichment of a vein takes place commonly in the points
where its two sides, being not far asunder, belong to the same rock; and
its impoverishment occurs when one side is calcareous and the other a
schistose clay. The minerals which most frequently accompany the galena,
are carbonate of lime, fluate of lime, sulphate of baryta, quartz, and
pyrites.

The pipe-veins (_amas_ in French), are seldom of great length; but some
have a considerable width; their composition being somewhat similar to
that of the _rake-veins_. They meet commonly in the neighbourhood of the
two systems, sometimes being in evident communication together; they are
occasionally barren; but when a wide pipe-vein is metalliferous, it is
said to be very productive.

The _flat veins_, or _strata veins_, seem to be nothing else than
expansions of the matter of the vein between the planes of the strata;
and contain the same ores as the veins in their vicinity. When they are
metalliferous, they are worked along with the adjacent rake vein; and
are productive to only a certain distance from that vein, unless they
get enriched by crossing a rake vein. Some examples have been adduced of
advantageous workings in _flat veins_ in the _great limestone_ of
Cumberland, particularly in the mines of Coalcleugh and Nenthead. The
_rake veins_, however, furnish the greater part of the lead which
Cumberland and the adjacent counties send every year into the market.
Mr. Forster gives a list of 165 lead mines, which have been formerly, or
are now, worked in that district of the kingdom.

The metalliferous limestone occupies, in Derbyshire, a length of about
25 miles from north-west to south-east, under a very variable breadth,
which towards the south, amounts to 25 miles. Castleton to the north,
Buxton to the north-west, and Matlock to the south-east, lie nearly upon
its limits. It is surrounded on almost all sides by the millstone grit
which covers it, and which is, in its turn, covered by the coal strata.
The nature of the rocks beneath the limestone is not known. In
Cumberland the metalliferous limestone includes a bed of trap,
designated under the name of _whinsill_. In Derbyshire the trap is much
more abundant, and it is thrice interposed between the limestone. These
two rocks constitute of themselves the whole mineral mass, through a
thickness of about 550 yards, measuring from the millstone grit; only in
the upper portion, that is near the millstone grit, there is a pretty
considerable thickness of argillo-calcareous schists.

Four great bodies or beds of limestone are distinguishable, which
alternate with three masses of trap, called toadstone. The lead veins
exist in the calcareous strata, but disappear at the limits of the
toadstone. It has now been ascertained however that they recur in the
limestone underneath.

_Treatment of the Ores of Lead._

The mechanical operations performed upon the lead ores in Great Britain,
to bring them to the degree of purity necessary for their metallurgic
treatment, may be divided into three classes, whose objects are,--

1. _The sorting and cleansing of the ores_;

2. _The grinding_;

3. _The washing, properly so called_.

The apparatus subservient to the first objects are sieves, running
buddles, and gratings. The large sieves employed in Derbyshire for
sorting the ore at the mouth of the mine, into coarse and fine pieces,
is a wire gauze of iron; its meshes are square, and an inch long in each
side. There is a lighter sieve of wire gauze, similar to the preceding,
for washing the mud from the ore, by agitating the fragments in a tub
filled with water. But in Derbyshire, instead of using this sieve, the
pieces of ore are sometimes merely stirred about with a shovel, in a
trough filled with water. This is called a _standing buddle_; a most
defective plan.

The _running buddle_ serves at once to sort and cleanse the ore. It
consists of a plane surface made of slabs or planks, very slightly
inclined forwards, and provided behind and on the sides with upright
ledges, the back one having a notch to admit a stream of water. The ore
is merely stirred about with a shovel, and exposed on the slope to the
stream. For this apparatus, formerly the only one used at the mines of
Alston Moor, the following has been substituted, called the _grate_. It
is a _grid_, composed of square bars of iron, an inch thick, by from 24
to 32 inches long, placed horizontally, and parallelly to each other, an
inch apart. There is a wooden canal above the grate, which conducts a
stream of water over its middle; and an inclined plane is set beneath
it, which leads to a hemispherical basin, about 24 inches inches in
diameter, for collecting the metallic powder washed out of the ore.

The apparatus subservient to grinding the ore are,--

1. The _bucker_, or beater, formed of a cast-iron plate, 3 inches
square, with a socket in its upper surface, for receiving a wooden
handle. In the neighbourhood of Alston Moor, crushing cylinders have
been substituted for the beating bucker; but even now, in Derbyshire,
buckers are generally employed for breaking the pieces of mixed ore,
called _knock-stone-stuff_.

At the mines of this county, the _knocker’s_ workshop, or _striking
floor_, is provided either with a strong stool, or a wall 3 feet high,
beyond which there is a flat area 4 feet broad, and a little raised
behind. On this area, bounded, except in front, by small walls, the ore
to be bruised is placed. On the stool, or wall, a very hard stone slab,
or cast-iron plate is laid, 7 feet long, 7 inches broad, and 1-1/2
inches thick, called a _knock-stone_. The workmen seated before it,
break the pieces of mixed ore, called _bowse_ in Derbyshire, with the
bucker.

_Crushing machines_ are in general use at Alston Moor, to break the
mingled ores, which they perform with great economy of time and labour.
They have been employed there for nearly forty years.

[Illustration: 628 629]

This machine is composed of one pair of fluted cylinders, _x x_, _fig._
628., and of two pairs of smooth cylinders _z z_, _z z_, which serve
altogether for crushing the ore. The two cylinders of each of the three
pairs turn simultaneously in an inverse direction, by means of two
toothed wheels, as at _m_, _fig._ 629., upon the shaft of every
cylinder, which work by pairs in one another. The motion is given by a
single water wheel, of which the circle _a a a_ represents the outer
circumference. One of the fluted cylinders is placed in the prolongation
of the shaft of this wheel, which carries besides a cast-iron toothed
wheel, geered with the toothed wheels _e e_, fixed upon the ends of two
of the smooth cylinders. Above the fluted cylinders, there is a hopper,
which discharges down between them, by means of a particular mechanism,
the ore brought forward by the waggons A. These waggons advance upon a
railway, stop above the hopper, and empty their contents into it through
a trap-hole, which opens outwardly in the middle of their bottom. Below
the hopper there is a small bucket called a shoe, into which the ore is
shaken down, and which throws it without ceasing upon the cylinders, in
consequence of the constant jolts given it by a crank-rod _i_ (_fig._
629.) attached to it, and moved by the teeth of the wheel _m_. The shoe
is so regulated, that too much ore can never fall upon the cylinders,
and obstruct their movement. A small stream of water is likewise led
into the shoe, which spreads over the cylinders, and prevents them from
growing hot. The ore, after passing between the fluted rollers, falls
upon the inclined planes N, N, which turn it over to one or other of the
pairs of smooth rolls.

These are the essential parts of this machine; they are made of iron,
and the smooth ones are case-hardened, or _chilled_, by being cast in
iron moulds. The gudgeons of both kinds move in brass bushes fixed upon
iron supports _k_, made fast by bolts to the strong wood-work basis of
the whole machine. Each of the horizontal bars has an oblong slot, at
one of whose ends is solidly fixed one of the plummer-blocks or bearers
of one of the cylinders _f_, and in the rest of the slot the
plummer-block of the other cylinder _g_ slides; a construction which
permits the two cylinders to come into contact, or to recede to such a
distance from each other, as circumstances may require. The movable
cylinder is approximated to the fixed one by means of the iron levers X
X, which carry at their ends the weights P, and rest upon wedges M,
which may be slidden upon the inclined plane N. These wedges then press
the iron bar O, and make it approach the movable cylinder by advancing
the plummer-block which supports its axis. When matters are so arranged,
should a very large or hard piece present itself to one of the pairs of
cylinders, one of the rollers would move away, and let the piece pass
without doing injury to the mechanism.

Besides the three pairs of cylinders which constitute essentially each
crushing machine, there is sometimes a fourth, which serves to crush the
ore when not in large fragments, for example, the _chats_ and _cuttings_
(the moderately rich and poorer pieces), produced by the first sifting
with the brake sieve, to be presently described. The cylinders composing
that accessory piece, which, on account of their ordinary use, are
called _chats-rollers_, are smooth, and similar to the rollers _z z_,
and Z´ Z´. The one of them is usually placed upon the prolongation of
the shaft of the water-wheel, of the side opposite to the principal
machine; and the other, which is placed alongside, receives its motion
from the first, by means of toothed wheel-work.

The _stamp mill_ is employed in concurrence with the crushing cylinders.
It serves particularly to pulverize those ores whose gangue is too hard
to yield readily to the rollers, and also those which being already
pulverized to a certain degree, require to be ground still more finely.
The stamps employed in the neighbourhood of Alston Moor are moved by
water wheels. They are similar to those described under TIN.

_Proper sifting or jigging apparatus._--The hand sieve made of iron wire
meshes, of various sizes, is shaken with the two hands in a tub of
water, the _ore vat_, being held sometimes horizontally, and at others
in an inclined position. This sieve is now in general use only for the
_cuttings_ that have passed through the grating, and which though not
poor enough to require finer grinding, are too poor for the brake sieve.
When the workman has collected a sufficient quantity of these smaller
pieces, he puts them in his round hand sieve, shakes it in the ore vat
with much rapidity and a dexterous toss, till he has separated the very
poor portions called _cuttings_, from the mingled parts called _chats_,
as well as from the pure ore. He then removes the first two qualities,
with a sheet-iron scraper called a _limp_, and he finds beneath them, a
certain portion of ore which he reckons to be pure.

The _brake sieve_ is rectangular, as well as the cistern in which it is
agitated. The meshes are made of strong iron wire, three-eighths of an
inch square. This sieve is suspended at the extremity of a forked lever,
or brake, turning upon an axis by means of two upright arms about 5 feet
long, which are pierced with holes for connecting them with bolts or
pins, both to the sieve-frame and to the ends of the two branches of the
lever. These two arms are made of wrought iron, but the lever is made of
wood; as it receives the jolt. A child placed near its end, by the
action of leaping, jerks it smartly up and down, so as to shake
effectually the sieve suspended at the other extremity. Each jolt not
only makes the fine parts pass through the meshes, but changes the
relative position of those which remain on the wires, bringing the purer
and heavier pieces eventually to the bottom. The mingled fragments of
galena, and the stony substances called _chats_ lie above them; while
the poor and light pieces called _cuttings_, are at top. These are first
scraped off by the _limp_, next the mixed lumps, or _chats_, and lastly
the pure ore, which is carried to the _bing heap_. The _cuttings_ are
handed to a particular class of workmen, who by a new sifting, divide
them into mere stones, or second _cuttings_, and into mixed ore
analogous to _chats_.

The poor ore, called _chats_, is carried to a crushing machine, where it
is bruised between two cylinders appropriated to this purpose under the
name of _chats_ rollers; after which it is sifted afresh. During the
sifting many parcels of small ore and stony substances pass through the
sieve, and accumulate at the bottom of the cistern. When it is
two-thirds filled, water is run slowly over it, and the sediment called
_smitham_ is taken out, and piled up in heaps. More being put into the
tub, a child lifts up the _smitham_, and lays it on the sieve, which
retains still on its meshes the layer of fine ore. The _sifter_ now
agitates in the water nearly as at first, from time to time removing
with the _limp_ the lighter matters as they come to the surface; which
being fit for washing only in boxes, are called _buddler’s offal_, and
and are thrown into the _buddle hole_.

Mr. Petherick, the manager of Lanescot and the Fowey Consol mines, has
contrived an ingenious jigging machine, in which a series of 8 sieves
are fixed in a stationary circular frame, connected with a plunger or
piston working in a hollow cylinder, whereby a body of water is
alternately forced up through the crushed ore in the sieves, and then
left to descend. In this way of operating, the indiscriminate or
premature passage of the finer pulverulent matter through the meshes is
avoided, because a regulated stream of water is made to traverse the
particles up and down. This mode has proved profitable in washing the
copper ores of the above mentioned copper mines.

_Proper washing apparatus._--For washing the ore after sifting it, the
running buddle already described is employed, along with several chests
or _buddles_ of other kinds.

1. The _trunk buddle_ is a species of German chest (see METALLURGY and
TIN) composed of two parts; of a cistern or box into which a stream of
water flows, and of a large tank with a smooth level bottom. The ore to
be _trunked_ being placed in the box, the workman furnished with a
shovel bent up at its sides, agitates it, and removes from time to time
the coarser portions; while the smaller are swept off by the water and
deposited upon the level area.

2. The _stirring buddle_, or chest for freeing the _schlamms_ or slimy
stuff from clay, is analogous to the German chests, and consists of two
parts; namely, 1. a trough which receives a stream of water through a
plug hole, which is tempered at pleasure, to admit a greater or less
current; 2. a settling tank with a horizontal bottom. The metallic
_slime_ being first floated in the water of the trough, then flows out
and is deposited in the tank; the purest parts falling first near the
beginning of the run.

3. The _nicking buddle_ is analogous to the tables called _dormantes_ or
_jumelles_ by the French miners. See METALLURGY. They have at their
upper end a cross canal or spout, equal in length to the breadth of the
table, with a plug hole in its middle for admitting the water. Alongside
of this channel there is a slightly inclined plank, called _nicking
board_, corresponding to the head of the _twin table_, and there is a
nearly level plane below. The operation consists in spreading a thin
layer of the _slime_ upon the _nicking board_, and in running over its
surface a slender sheet of water, which in its progress is subdivided
into rills, which gradually carry off the muddy matters, and strew them
over the lower flat surface of the tank, in the order of their density.

[Illustration: 630]

4. The _dolly tub_ or rinsing bucket, _fig._ 630., has an upright shaft,
which bears the vane or _dolly_ A B, turned by the winch handle. This
apparatus serves to bring into a state of suspension in water, the fine
ore, already nearly pure; the separation of the metallic particles from
the earthy ones by repose, being promoted by the sides of the tub being
struck frequently during the subsidence.

5. _Slime pits._--In the several operations of cleansing ores from mud,
in grinding, and washing, where a stream of water is used, it is
impossible to prevent some of the finely attenuated portions of the
galena called _sludge_, floating in the water, from being carried off
with it. _Slime pits_ or _labyrinths_, called _buddle holes_ in
Derbyshire, are employed to collect that matter, by receiving the water
to settle, at a little distance from the place of agitation.

These basins or reservoirs are about 20 feet in diameter, and from 24 to
40 inches deep. Here the suspended ore is deposited, and nothing but
clear water is allowed to escape.

The workmen employed in the mechanical preparation of the ores, are
paid, in Cumberland, by the piece, and not by day’s wages. A certain
quantity of crude ore is delivered to them, and their work is valued by
the _bing_, a measure containing 14 cwt. of ore ready for smelting. The
price varies according to the richness of the ore. Certain qualities are
washed at the rate of two and sixpence, or three shillings the bing;
while others are worth at least ten shillings. The richness of the ore
varies from 2 to 20 bings of galena per _shift_ of ore; the shift
corresponding to 8 waggons load.

1. The cleansing and sorting of the ores are well performed in
Cumberland. These operations seem however to be inferior to the
cleansing on the _grid steps_, _grilles à gradin_, of Saxony (see
METALLURGY), an apparatus which in cleaning the ores, has the advantage
of grouping them in lots of different qualities and dimensions.

2. The breaking or bruising by means of the _crushing machine_, is much
more expeditious than the Derbyshire process by _buckers_; for the
machine introduces not only great economy into the breaking operation,
but it likewise diminishes considerably the loss of galena; for stamped
ores may be often subjected to the action of the cylinders without
waste, while a portion of them would have been lost with the water that
runs from the stamp mill. The use of these rollers may therefore be
considered as one of the happiest innovations hitherto made in the
mechanical preparation of ores.

3. The _brake sieves_ appear to be preferable to the hand ones.

4. The system of washing used in Cumberland differs essentially from
that of Brittany. The slime pits are constructed with much less care
than in France and Germany. They never present, as in these countries,
those long windings backwards and forwards, whence they have been called
labyrinths; probably because the last deposits, which are washed with
profit in France and Germany, could not be so in Cumberland. There is
reason to believe, however, that the introduction of _brake tables_,
(_tables à secousses_, see METALLURGY) would enable deposits to be
saved, which at present run to waste in England.

5. From what we have now said about the system of washing, and the
basins of deposit or settling cisterns, it may be inferred that the
operation followed in Cumberland is more expeditious than that used in
Brittany, but it furnishes less pure ores, and occasions more
considerable waste; a fact sufficiently obvious, since the refuse stuff
at Poullaouen is often resumed, and profitably subjected to a new
preparation. We cannot however venture to blame this method, because in
England, fuel being cheap, and labour dear, there may possibly be more
advantage in smelting an ore somewhat impure, and in losing a little
galena, than in multiplying the number of washing processes.

6. Lastly, the _dolly tub_ ought to be adopted in all the establishments
where the galena is mixed with much blende (sulphuret of zinc); for
_schlich_ (metallic slime) which appears very clean to the eye, gives
off a considerable quantity of blende by means of the _dolly tub_. While
the vane is rapidly whirled, the sludge is gradually let down into the
revolving water, till the quantity is sufficiently great. Whenever the
ore is thoroughly disseminated in the liquid, the dolly is withdrawn.
The workmen then strike on the sides of the tub for a considerable time,
with mallets or wooden billets, to make the slime fall fast to the
bottom. The lighter portions, consisting almost entirely of refuse
matter, fall only after the knocking has ceased; the water is now run
away; then the very poor slime upon the top of the deposit is skimmed
off; while the pure ore found at the bottom of the tub is lifted out,
and laid on the _bingstead_. In this way the blende, which always
accompanies galena in a greater or smaller quantity, is well separated.

_Smelting of lead ores._--The lead ores of Derbyshire and the north of
England were antiently smelted in very rude furnaces, or _boles_, urged
by the natural force of the wind, and were therefore placed on the
summits or western slopes of the highest hills. More recently these
furnaces were replaced by blast hearths, resembling smith’s forges, but
larger; and were blown by strong bellows, moved by men or water-wheels.
The principal operation of smelting is at present always executed in
Derbyshire in _reverberatory furnaces_, and at _Alston Moor_ in furnaces
similar to those known in France by the name of Scotch furnaces. Before
entering into the detail of the founding processes, we shall give a
description of the furnaces essential for both the smelting and
accessory Operations.

1. The reverberatory furnace called cupola, now exclusively used in
Derbyshire for the smelting of lead ores, was imported thither from
Wales, about the year 1747, by a company of Quakers. The first
establishment in this county was built at Kalstedge, in the district of
Ashover.

In the works where the construction of these furnaces is most improved,
they are interiorly 8 feet long by 6 wide in the middle, and two feet
high at the centre. The fire, placed at one of the extremities, is
separated from the body of the furnace by a body of masonry, called the
_fire-bridge_, which is two feet thick, leaving only from 14 to 18
inches between its upper surface and the vault. From this, the highest
point, the vault gradually sinks towards the further end, where it
stands only 6 inches above the sole. At this extremity of the furnace,
there are two openings separated by a triangular prism of _fire-stone_,
which lead to a flue, a foot and a half wide, and 10 feet long, which is
recurved towards the top, and runs into an upright chimney 55 feet high.
The above flue is covered with stone slabs, carefully jointed with
fire-clay, which may be removed when the deposit formed under them
(which is apt to melt), requires to be cleaned out. One of the sides of
the furnace is called the labourers’ side. It has a door for throwing
coal upon the fire-grate, besides three small apertures each about 6
inches square. These are closed with movable plates of cast iron, which
are taken off when the working requires a freer circulation of air, or
for the stirring up of the materials upon the hearth. On the opposite
side, called the working side, there are five apertures; namely, three
equal and opposite to those just described, shutting in like manner with
cast iron plates, and beneath them two other openings, one of which is
for running out the lead, and another for the scoriæ. The ash pit is
also on this side, covered with a little water, and so disposed as that
the grate-bars may be easily cleared from the cinder slag.

The hearth of the furnace is composed of the reverberatory furnace
slags, to which a proper shape has been given by beating them with a
strong iron rake, before their entire solidification. On the labourers’
side, this hearth rises nearly to the surface of the three openings, and
falls towards the working side, so as to be 18 inches below the middle
aperture. In this point, the lowest of the furnace, there is a tap-hole,
through which the lead is run off into a large iron boiler (lea-pan),
placed in a recess left outside in the masonry. From that lowest point,
the sole gradually rises in all directions, forming thus an inside
basin, into which the lead runs down as it is smelted. At the usual
level of the metal bath, there is on the working side, at the end
furthest from the fire, an aperture for letting off the slag.

In the middle of the arched roof there is a small aperture, called the
_crown-hole_, which is covered up during the working with a thick cast
iron plate. Above this aperture a large wooden or iron hopper stands,
leading beneath into an iron cylinder, through which the contents of the
hopper may fall into the furnace when a trap or valve is opened.

2. _The roasting furnace._--This was introduced about 30 years ago, in
the neighbourhood of Alston Moor, for roasting the ore intended to pass
through the Scotch furnace, a process which greatly facilitates that
operation. Since its first establishment it has successively received
considerable improvements.

[Illustration: 631 632 633]

_Figs._ 631, 632, 633., represent the cupola furnace at the Marquess of
Westminster’s lead smelting works, two miles from Holywell. The hearth
is hollowed out below the middle door of the furnace; it slopes from
the back and ends towards this basin. The distance from the lowest point
of this concavity up to the sill of the door, is usually 24 inches, but
it is sometimes a little less, according to the quality of the ores to
be smelted. This furnace has no hole for running off the slag, above the
level of the top hole for the lead _i_, like the smelting furnace of
Lea, near Matlock. A single chimney stalk serves for all the
establishments; and receives all the flues of the various roasting and
reducing furnaces. _Fig._ 633. gives an idea of the distribution of
these flues. _a a a_, &c. are the furnaces; _b_, the flues, 18 inches
square; these lead from each furnace to the principal conduit _c_, which
is 5 feet deep by 2-1/2 wide; _d_ is 6 feet deep by 3 wide; _e_ is a
round chamber 15 feet in diameter; _f_ is a conduit 7 feet high by 5
wide; _g_ another, 6 feet high by 3 wide. The chimney at _h_ has a
diameter at bottom of 30 feet, at top of 12 feet, including the
thickness of its sides, forming a truncated cone 100 feet high; whose
base stands upon a hill a little way from the furnaces, and 62 feet
above their level.

_a_, _figs._ 631, 632., is the grate; _b_, the door of the fire-place;
_c_, the fire-bridge; _d_, the arched roof; _e_, the hearth; _f f f_,
&c., the working doors; _g g_, flues running into one conduit, which
leads to the subterranean condensing chamber, _e_, and thence to the
general chimney; _h_, a hopper-shaped opening in the top of the furnace,
for supplying it with materials.

This magnificent structure is not destined solely for the reduction of
the ores, but for dissipating all the vapours which might prove noxious
to the health of the work-people and to vegetation.

The ores smelted at Holywell are very refractory galenas, mixed with
blende, calamine, pyrites, carbonate of lime, &c., but without any
fluate of lime. They serve mutually as fluxes to one another. The coal
is of inferior quality. The sole of each furnace is formed of slags
obtained in the smelting, and they are all of one kind. In constructing
it, 7 or 8 tons of these slags are first of all thrown upon the brick
area of the hearth; are made to melt by a brisk fire, and in their
stiffening state, as they cool, they permit the bottom to be sloped and
hollowed into the desired shape. Four workmen, two at each side of the
furnace, perform this task.

The ordinary charge of ore for one smelting operation is 20 cwt., and it
is introduced through the hopper; see COPPER, _fig._ 304. An assistant
placed at the back doors spreads it equally over the whole hearth with a
rake; the furnace being meanwhile heated only with the declining fire of
a preceding operation. No regular fire is made during the first two
hours, but a gentle heat merely is kept up by throwing one or two
shovelfuls of small coal upon the grate from time to time. All the doors
are closed, and the register-plate of the chimney is lowered.

The outer basin in front of the furnace is at this time filled with the
lead derived from a former process, the metal being covered with slags.
A rectangular slit above the tap hole is left open, and remains so
during the whole time of the operation, unless the lead should rise in
the interior basin above the level of that orifice; in which case a
little mound must be raised before it.

The two doors in front furthest from the fire being soon opened, the
head-smelter throws in through them, upon the sole of the furnace, the
slags swimming upon the bath of lead, and a little while afterwards he
opens the tap-hole, and runs off the metallic lead reduced from these
slags. At the same time his assistant turns over the ore with his
paddle, through the back doors. These being again closed, while the
above two front doors are open, the smelter throws a shovelful of small
coal or coak cinder upon the lead bath, and works the whole together,
turning over the ore with the paddle or iron oar. About three quarters
of an hour after the commencement of the operation, he throws back upon
the sole of the hearth the fresh slags which then float upon the bath of
the outer basin, and which are mixed with coaly matter. He next turns
over these slags, as well as the ore with the paddle, and shuts all the
doors. At this time the smelter runs off the lead into the pig-moulds.

The assistant now turns over the ore once more through the back doors. A
little more than an hour after the operation began, a quantity of lead
proceeding from the slag last remelted, is run off by the tap; being
usually in such quantity as to fill one half of the outer basin. Both
the workmen then turn over the ore with the paddles, at the several
doors of the furnace. Its interior is at this time of a dull red heat;
the roasting being carried on rather by the combustion of the sulphurous
ingredients, than by the action of the small quantity of coal in the
grate. The smelter, after shutting the front doors, with the exception
of that next the fire-bridge, lifts off the fresh slags lying upon the
surface of the outside bath, drains them, and throws them back into the
furnace.

An hour and a half after the commencement, the lead begins to ooze out
in small quantities from the ore; but little should be suffered to flow
before two hours have expired. About this time the two workmen open all
the doors, and turn over the ore, each at his own side of the furnace.
An hour and three quarters after the beginning, there are few vapours
in the furnace, its temperature being very moderate. No more lead is
then seen to flow upon the sloping hearth. A little coal being thrown
into the grate to raise the heat slightly, the workmen turn over the
ore, and then close all the doors.

At the end of two hours, the _first fire_ or roasting being completed,
and the doors shut, the register is to be lifted a little, and coal
thrown upon the grate to give the _second fire_, which lasts during 25
minutes. When the doors are now opened, the inside of the furnace is of
a pretty vivid red, and the lead flows down from every side towards the
inner basin. The smelter with his rake or paddle pushes the slags upon
that basin back towards the upper part of the sole, and his assistant
spreads them uniformly over the surface through the back doors. The
smelter next throws in by his middle door, a few shovelfuls of quicklime
upon the lead bath. The assistant meanwhile, for a quarter of an hour,
works the ore and the slags together through the three back doors, and
then spreads them out, while the smelter pushes the slags from the
surface of the inner basin back to the upper parts of the sole. The
doors being now left open for a little, while the interior remains in
repose, the metallic lead, which had been pushed back with the slags,
flows down into the basin. This occasional _cooling_ of the furnace is
thought to be necessary for the better separation of the products,
especially of the slags from the lead bath.

In a short time the workmen resume their rakes, and turn over the slags
along with the ore. Three hours after the commencement, a little more
fuel is put into the grate, merely to keep up a moderate heat of the
furnace during the paddling. After three hours and ten minutes, the
grate being charged with fuel for the _third fire_, the register is
completely opened, the doors are all shut, and the furnace is left in
this state for three quarters of an hour. In nearly four hours from the
commencement, all the doors being opened, the assistant levels the
surfaces with his rake, in order to favour the descent of any drops of
lead; and then spreads the slags, which are pushed back towards him by
the smelter. The latter now throws in a fresh quantity of lime, with the
view not merely of covering the lead bath and preventing its
oxidizement, but of rendering the slags less fluid.

Ten minutes after the third fire is completed, the smelter puts a new
charge of fuel in the grate, and shuts the doors of the furnace to give
it the _fourth fire_. In four hours and forty minutes from the
commencement, this fire being finished, the doors are opened, the
smelter pierces the tap-hole to discharge the lead into the outer basin,
and throws some quicklime upon the slags in the inner basin. He then
pushes the slags thus _dried up_ towards the upper part of the hearth,
and his assistant rakes them out by the back doors.

The whole operation of a _smelting shift_ takes about four hours and a
half, or at most five hours, in which four periods may be distinguished.

1. The _first fire_ for roasting the ores, requires very moderate
firing, and lasts two hours.

2. The _second fire_, or the smelting, requires a higher heat, with shut
doors; at the end the slags are _dried up_ with lime, and the furnace is
also allowed to cool a little.

3, 4. The last two periods, or the _third and fourth fires_, are
likewise two smeltings or foundings, and differ from the first only in
requiring a higher temperature. The heat is greatest in the last. The
form and dimensions of the furnace are calculated to cause a uniform
distribution of heat over the whole surface of the hearth. Sometimes
billets of green wood are plunged into the metallic lead of the outer
basin, causing an ebullition which favours the separation of the slags,
and consequently the production of a purer lead; but no more metallic
metal is obtained.

Ten cwts. of coal are consumed at Holywell in smelting one ton of the
lead-ore _schlich_ or sludge; but at Grassington, near Skipton in
Yorkshire, with a similar furnace worked with a slower heat, the
operation taking from seven hours to seven hours and a half, instead of
five, only 7-1/2 cwts. of coal are consumed. But here the ores are less
refractory, have the benefit of fluor spar as a flux, and are more
exhausted of their metal, being smelted upon a less sloping hearth.

_Theory of the above operations._--At Holywell, Grassington, and in
Cornwall, the result of the first graduated roasting heat, is a mixture
of undecomposed sulphuret of lead, with sulphate and oxide of lead, in
proportions which vary with the degree of care bestowed upon the
process. After the roasting, the heat is raised to convert the sludge
into a pasty mass; in which the oxide and sulphate re-act upon the
sulphuret, so as to produce a sub-sulphuret, which parts with the metal
by liquation. The _cooling of the furnace_ facilitates the liquation
every time that the sub-sulphuret is formed, and the ore has passed by
increase of temperature from the pasty into the liquid state. _Cooling_
brings back the sludge to the pasty condition, and is therefore
necessary for the due separation of the different bodies. The drying up
of the thin slags by lime is intended to liberate the oxide of lead, and
allow it to re-act upon any sulphuret which may have resisted roasting
or decomposition. It is also useful as a _thickener_, in a mechanical
point of view. The iron of the tools, which wear away very fast, is also
serviceable in reducing the sulphuret of lead. The small coal added
along with the lime at Grassington, and also sometimes at Holywell, aids
in reducing the oxide of lead, and in transforming the sulphate into
sulphuret.

[Illustration: 634]

3. _The smelting furnace or ore hearth._--This furnace, called by the
French _écossais_, is from 22 to 24 inches in height and 1 foot by 1-1/2
in area inside; but its horizontal section, always rectangular, varies
much in its dimensions at different levels, as shown in _fig._ 634.

The hearth and the sides are of cast iron; the sole-plate A B is also of
cast iron, 2-1/2 inches thick, having on its back and two sides an
upright ledge, A C, 2-1/2 inches thick, and 4-1/4 high. In front of the
hearth there is another cast iron plate M N, called the _work-stone_,
surrounded on every side excepting towards the sole of the furnace, by a
ledge one inch in thickness and height. The plate slopes from behind
forwards, and its posterior ledge, which is about 4-1/2 inches above the
surface of the hearth, is separated from it by a void space _q_, which
is filled with a mixture of bone ash and galena, both in fine powder,
moistened and pressed down together. The melted lead cannot penetrate
into this body, but after filling the basin at the bottom of the
furnace, flows naturally out by the gutter (nearly an inch deep) through
a groove in the _work-stone_; and then passes into a cauldron of
reception P, styled the _melting-pot_, placed below the front edge of
the _work-stone_.

The posterior ledge of the sole is surmounted by a piece of cast iron C
D, called the _back-stone_, 28 inches long, and 6-1/2 high; on which the
_tuyère_ or blast-pipe is placed. It supports another piece of cast iron
E, called _pipe-stone_, scooped out at its under part, in the middle of
its length, for the passage of the _tuyère_. This piece advances 2
inches into the interior of the furnace, the back wall of which is
finally crowned by another piece of cast iron E H, called also
_back-stone_.

On the ledges of the two sides of the sole, are placed two pieces of
cast iron, called _bearers_, each of which is 5 inches in breadth and
height, and 26 inches long. They advance an inch or two above the
posterior and highest edge of the _work-stone_, and contribute
effectually to fix it solidly in its place. These bearers support,
through the intervention of several ranges of fire-bricks, a piece of
cast iron called a _fore-stone_, which has the same dimensions as the
piece called the _back-stone_, on which the base of the blowing-machine
rests. This piece is in contact, at each of its extremities, with
another mass of cast iron, 6 inches cube, called the _key-stone_,
supported on the masonry. Lastly, the void spaces left between the two
_key-stones_ and the back part of the furnace are filled up with two
masses of cast iron exactly like the key-stones.

The front of the furnace is open for about 12 inches from the lower part
of the front cross-piece called _fore-stone_, up to the superior part of
the _work-stone_. It is through this opening that the smelter operates.

The gaseous products of the combustion, on escaping from this
ore-hearth, are frequently made to pass through a long flue, sloped very
slightly upwards, in which they deposit all the particles of ore that
they may have swept along; these flues, whose length is sometimes more
than 100 yards, are usually 5 feet high and 3 feet wide in the inside,
and always terminate in a chimney stalk. The matters deposited near the
commencement of the flue require to be washed; but not the other dusty
deposits. The whole may then be carried back to the roasting furnace, to
be calcined and re-agglutinated, or introduced without any preparation
into the _slag-hearth_.

[Illustration: 635 636]

4. _Figs._ 635, 636. represent a slag-hearth, the _fourneau à manche_
(elbow furnace) of the French, and the _krummofen_ (crooked furnace) of
the Germans; such as is used at Alston Moor, in Cumberland, for the
reduction of the lead-slag. It resembles the Scotch furnace. The shaft
is a parallelopiped, whose base is 26 inches by 22 in area inside, and
whose height is 3 feet; the sole-plate _a_, of cast iron, slopes
slightly down to the basin of reception, or the fore-hearth _b_. Upon
both of the long sides of the sole-plate there are cast iron beams,
called _bearers_ C C, of great strength, which support the side walls
built of a coarse grained sand-stone, as well as the cast-iron plate _d_
(_fore-stone_), which forms the front of the shaft. This stands 7
inches off from the sole-plate, leaving an empty space between them. The
back side is made of cast iron, from the sole-plate to the horizontal
tuyère in its middle; but above this point it is made of sand-stone. The
tuyère is from 1-1/5 to 2 inches in diameter. In front of the
fore-hearth _b_, a cistern _e_, is placed, through which water
continually flows, so that the slags which spontaneously overflow the
fore-hearth may become inflated and shattered, whereby the lead
disseminated through them may be readily separated by washing. The lead
itself flows from the fore-hearth _b_, through an orifice, into an iron
pot _f_, which is kept hot over a fire. The metal obtained from this
slag-hearth is much less pure than that extracted directly from the ore.

The whole bottom of the furnace is filled to a height of 17 inches, that
is, to within 2 or 3 inches of the tuyère, with the rubbish of coke
reduced to coarse powder and beat strongly down. At each _smelting
shift_, this bed must be made anew, and the interior of the furnace
above the tuyère repaired, with the exception of the front, consisting
of cast iron. In advance of the furnace there is a basin of reception,
which is also filled with coke rubbish. Farther off is a pit, full of
water, replenished by a cold stream, which incessantly runs in through a
pipe. The scoriæ, in flowing out of the furnace, pass over the coke bed
in the basin of reception, and then fall into the water, whose coolness
makes them fly into small pieces, after which they are easily washed, so
as to separate the lead that may be entangled among them.

[Illustration: 637]

These furnaces are urged, in general, by wooden bellows; _fig._ 637. But
at the smelting works of Lea, near Matlock, the blowing-machine consists
of two casks, which move upon horizontal axes. Each of these casks is
divided into two equal parts by a fixed plane that passes through its
axis, and is filled with water to a certain height. The water of one
side communicates with that of the other by an opening in the lower part
of the division. Each cask possesses a movement of oscillation, produced
by a rod attached to a crank of a bucket-wheel. At each
demi-oscillation, one of the compartments, being in communication with
the external air, is filled; whilst the other, on the contrary,
communicates with the nozzle, and supplies wind to the furnace.

5. _Refining or cupellation furnace._ See SILVER.

6. _Smelting by the reverberatory furnace_, is adopted exclusively in
Derbyshire, and in some works at Alston-moor. The charge in the hopper
consists commonly of 16 cwt., each weighing 120 lbs. avoirdupois,
composed of an intimate mixture of 5, 6, 7 or even 8 kinds of ore,
derived from different mines, and prepared in different ways. The
proportions of the mixture are determined by experience, and are of
great consequence to the success of the work.

The ore is rather in the form of grains than of a fine _schlich_; it is
sometimes very pure, and affords 75 _per cent._; but usually it is mixed
up with a large proportion of carbonate and fluate of lime; and its
product varies from 65 to 23 _per cent._

After scraping the slaggy matters out of the furnace, a fresh smelting
shift is introduced at an interval of a few minutes; and thus, by means
of two alternate workmen, who relieve each other every seven or eight
hours, the weekly operations continue without interruption. The average
product in lead of the reverberatory furnaces in Derbyshire, during
several years, has been 66 per cent. of the ore. Very fine ore has,
however, afforded 76.

7. _Smelting of the drawn slag, on the slag-mill hearth._--The black
slag of the reverberatory furnace is broken by hammers into small
pieces, and mixed in proper proportions with the coal cinders that fall
through the grate of the reverberatory fire. The leaden _matts_ that
float on the surface of the bath, and the dust deposited in the chimney,
are added, along with some poor ore containing a gangue of fluor spar
and limestone, which had been put aside during the mechanical
preparation. With such a mixture, the slag-hearth, already described,
_figs._ 635, 636., is charged. By the action of heat and coal, the lead
is revived, the earthy matters flow into very liquid scoriæ, and the
whole is made to pass across the body of fire into a basin of reception
placed beneath. The scoriæ are thickened by throwing quicklime upon
them, and they are then raked away. At the end of the operation the lead
is cast into pigs or ingots of a peculiar form. This is called
slag-lead. It is harder, more sonorous than the lead obtained from the
reverberatory furnace, and is preferred for the manufacture of minium,
lead shot, and some other purposes.

8. _Treatment of lead ores by the Scotch furnace, or ore-hearth._--This
furnace is generally employed in the counties of Northumberland,
Cumberland, and Durham, for the smelting of lead ores, which were
formerly carried to them without any preparation, but now they are
exposed to a preliminary calcination. The roasted ore yields in the
Scotch furnace a more considerable product than the crude ore, because
it forms in the furnace a more porous mass, and at the same time _it
works drier_, to use the founders’ expression; that is, it allows the
stream of air impelled by the bellows to diffuse itself more completely
across the matters contained in the furnace.

The charge of the _roasting_ furnace, _figs._ 631, 632, 633., is from 9
to 11 cwt. of ore, put into the furnace without any addition. Three such
shifts are usually passed through in eight hours. The fire should be
urged in such a manner as to produce constantly a dense smoke, without
letting any part of the ore melt and form a slag; an accident which
would obstruct the principal end of the process, which is to burn off
the sulphur and antimony, and to expel the carbonic acid of the
carbonate of lead. The ore must be frequently turned over, by moving it
from the bridge to the other end and back again. To prevent the ore from
running into masses as it cools, it is made to fall out of the furnace
into a pit full of water, placed below one of the lateral doors.

_Smelting of the lead ores in the Scotch furnace._--When a _smelting
shift_ has been finished in the Scotch furnace, a portion of the ore,
called _browse_, remains in a semi-reduced state, mixed with coke and
cinders. It is found of more advantage to preserve the browse for
beginning the following operation, than to take raw or even roasted ore.
To set the furnace in action, the interior of it is filled with peats,
cut into the form of bricks. The peats towards the posterior part are
heaped up without order, but those near the front are piled up with care
in the form of a wall. A kindled peat is now placed before the nozzle of
the bellows, which are made to blow, and the blast spreads the
combustion rapidly through the whole mass. To increase the heat, and to
render the fire more steady and durable, a few shovelfuls of coals are
thrown over the turf. A certain quantity of the browse is to be next
introduced; and then (or sometimes before all the browse is put in) the
greater part of the matters contained in the furnace is drawn over on
the _work-stone_, by means of a large rake called a _gowelock_; the
refuse of the ore called _gray slag_, which a skilful smelter knows by
its shining more than the browse, is taken off with a shovel, and thrown
to the right hand into a corner outside of the furnace. The browse left
on the work-stone is to be now thrown back into the furnace, with the
addition of a little coal, if necessary. If the browse be not well
cleaned from the slag, which is perceived by the whole mass being in a
soft state, and shewing a tendency to fuse, quicklime must be added,
which by its affinity for the argillaceous, siliceous, and ferruginous
substances, dries up the materials, as the smelters say, and gives to
the earthy parts the property of concreting into lumps or balls; but if,
on the other hand, the siliceous, argillaceous, or ferruginous parts
contained in the ore be too refractory, lime is also to be added, but in
smaller quantity, which, by rendering them more fusible, communicates
the property of concreting into balls. These lumps, called gray slag,
contain from one-tenth to one-fifteenth of the lead which was present in
the ore. They must be smelted afterwards at a higher temperature in the
slag hearth, to extract their lead. After the browse has been thrown
back into the furnace, as has been said, a few shovelfuls of ore are to
be strewed over it; but before doing this, and after removing the
scoriæ, there must be always placed before the tuyère half a peat, a
substance which, being extremely porous and combustible, not only
hinders any thing from entering the nozzle of the bellows, but spreads
the blast through all the vacant parts of the furnace. After an interval
of from 10 to 15 minutes, according to circumstances, the materials in
the furnace are drawn afresh upon the work-stone, and the gray slag is
removed by the rake. Another peat being placed before the tuyère, and
coal and quicklime being introduced in suitable proportions, the browse
is thrown back into the furnace, a fresh portion of ore is charged above
it, and left in the furnace for the above mentioned time.

This mode of working, continued for 14 or 15 hours, forms what is called
a _smelting shift_; in which time from 20 to 40 cwt. of lead, and even
more, are produced.

By this process the purest part of the lead, as well as the silver, are
sweated out, as it were, from the materials, with which they are mixed,
without any thing entering into fusion except these two metals in the
state of alloy. It is probable that the moderate temperature employed in
the Scotch furnace is the main cause of the purity of the lead which it
yields.

9. _Smelting of the scoriæ of the Scotch furnace on the slag
hearth._--Before putting fire to the slag hearth already described,
_figs._ 635, 636., its empty space is to be filled with peats, and a
lighted one being placed before the tuyère, the bellows are made to
play. A layer of coke is to be now thrown upon the burning peats, and as
soon as the heat is sufficiently high, a layer of the _gray slag_ is to
be introduced, or of any other scoriæ that are to be reduced. From time
to time, as the fit moment arrives, alternate strata of coke and slag
are to be added. In this operation, though the slag and the lead are
brought to a state of perfect fluidity; the metal gets separated by
filtering down through the bed of peat cinders, which the slag cannot do
on account of its viscidity. Whenever that coke bed becomes covered with
fluid slag, the workman makes a hole in it, of about an inch diameter,
by means of a kneed poker; and runs it off by this orifice, as it cannot
sink down into the hard rammed cinders, which fill the basin of
reception. The slag flows over it in a glowing stream into the pit
filled with water, where it gets granulated and ready for washing.

When lead is obtained from galena without the addition of combustible
matter, we have an example on the great scale, of the mutual
decomposition of the oxides and sulphates formed during the roasting
heat, by the still undecomposed galena, especially when this action is
facilitated by working up and skilfully mingling the various matters, as
happens in the reverberatory and Scotch furnaces. It is therefore the
sulphuret of lead itself which serves as the agent of reduction in
regard to the oxide and sulphate, when little or no charcoal has been
added. Sometimes, however, towards the end of the operation in the
reverberatory hearth, it becomes necessary to throw in some wood or
charcoal, because the oxidizement having become too complete, there does
not remain a sufficient body of sulphuret of lead to effect the
decompositions and reductions just mentioned, and therefore it is
requisite to regenerate some galena by means of carbonaceous matter,
which immediately converts the sulphate of lead into the sulphuret. The
sulphur and oxygen are eventually all separated in the form of
sulphurous acid. Roasted galena contains sometimes no less than 77 per
cent. of sulphate of lead.

At Viconago in the Valais, the process of smelting lead ore in the
reverberatory furnace with the addition of iron, as practised at Vienne
on the Isère, was introduced; but the difficulty of procuring a
sufficient supply of old iron has led to an interesting modification.

On the hearth of the reverberatory furnace, 10 quintals of moderately
rich ore are spread; these are heated temperately for some time, and
stirred about to promote the sublimation of the sulphur. After three or
four hours, when the ore seems to be sufficiently de-sulphuretted, the
heat is raised so as to melt the whole materials, and whenever they flux
into a metallic glass, a few shovelfuls of bruised charcoal or cinders
are thrown in, which soon thicken the liquid, and cause metallic lead to
appear. By this means three-fourths of the lead contained in the ore are
usually extracted; but at length the substance becoming less and less
fluid, yields no more metal. Stamped and washed carbonate of iron
(sparry iron ore) is now added, in the proportion of about 10 per cent.
of the lead ore primarily introduced.

On stirring and working together this mixture, it assumes the
consistence of a stiff paste, which is raked out of the furnace. When
this has become cold, it is broken into pieces, and thereafter smelted
in a slag-hearth, without the addition of flux. By this operation,
almost the whole lead present is obtained. 100 quintals of schlich yield
45 of argentiferous lead; and in the production of 100 quintals (cwts.)
of marketable lead, 140 cubic feet of beech-wood, and 357-1/2 quintals
of charcoal are consumed.

This process is remarkable for the use of iron-ore in smelting galena.

10. _Reduction in the reverberatory furnace, of the litharge obtained in
the refining of lead._--The litharge of Alston Moor is seldom sold as
such, but is usually converted into lead, in a reverberatory furnace.

In commencing this reduction, a bed of coal about 2 inches thick is
first of all laid on the hearth; which is soon kindled by the flame of
the fire-place, and in a little while is reduced to red hot cinders.
Upon these a certain quantity of a mixture of litharge and small coal is
uniformly spread; the heat of the fire-place being meanwhile so managed
as to maintain in the furnace a suitable temperature for enabling the
combustible to deprive the litharge of its oxygen, and to convert it
into lead. The metal is run out by the tap-hole into an iron pot; and
being cast into pigs of half a hundred weight, is sold under the name of
refined lead at a superior price.

The quantity of small coal mixed with the litharge, should be somewhat
less than what may be necessary to effect the reduction, because if in
the course of the process, a deficiency of it is perceived in any part
of the furnace, more can always be added; whereas a redundancy of coal
necessarily increases the quantity of slag, which, at the end of the
shift, must be removed from the furnace before a new operation is begun,
whereby lead is lost. In the reverberatory furnace, six fodders of lead
may be revived in nine or ten hours; during the first six of which the
mixture of litharge and coal is added at short intervals. A fodder is
from 21 to 24 cwts.

It deserves to be remarked that the work does not go on so well nor so
quick when the coal and litharge are in a pulverulent form; because the
reduction in this case takes place only at the surface, the air not
being able to penetrate into the body, and to keep up its combustion,
and the mutual action of the litharge and carbon in the interior. But on
the other hand, when the litharge is in porous pieces as large as a
hen’s egg, the action pervades the whole body, and the sooty fumes of
the coal effect the reduction even in the centre of the fragments of the
litharge, penetrating into every fissure and carrying off the oxygen.
The heat ought never to be urged so far as to melt the litharge.

The grounds of the cupel, and the slag of the reduction furnace, being a
mixture of small coke, coal ash, and oxide of iron, more or less
impregnated with lead, are smelted upon the _slag hearth_, along with
coke, and by way of flux, with a certain quantity of the black scoriæ
obtained from the same furnace, prepared for this purpose, by running it
out in thin plates, and breaking it into small pieces. The lead thus
obtained is usually very white, very hard, and not susceptible of
refinement.

MM. Dufrénoy and Beaumont consider the smelting of lead ore by the
reverberatory furnace as practised in Derbyshire, as probably preferable
to that with the slag hearth as carried on in Brittany; a process which
seldom gives uniform products, while it occasions a more considerable
waste of lead, and consumption of fuel.

The mixed process employed in Cumberland of roasting the ore, and
afterwards smelting it in a small furnace resembling that called the
Scotch, apparently yields a little less lead than if both operations
were executed in the reverberatory furnace; but according to Mr.
Forster, (see his _Treatise on a Section of the Strata from Newcastle
upon Tyne_, &c.) this slight loss is more than compensated by the
smaller consumption of fuel, the increased rapidity of the operation,
and especially by the much greater purity of the lead obtained from the
Scotch furnace. When it comes to be refined, the loss is only about
one-twelfth or one-thirteenth, whereas the lead revived in the
reverberatory furnace, loses frequently a ninth. Moreover, the lead
furnished by the first method admits of being refined with profit, when
it yields only 5 ounces of silver _per_ fodder of 20 quintals, _poids de
marc_, while that produced by the reverberatory furnace cannot be
cupelled unless it gives 10 ounces per fodder; and as in the English
cupellation, lead is constantly added anew without skimming, the
litharge obtained in the second case can never be brought into the
market, whereas the litharge of the leads from the Scotch furnace is of
good quality. See the new method of enriching lead for cupellation,
under SILVER.

As the _smelting_ of galena, the principal ore of lead, is not a little
complex, the following tabular view of the different processes may prove
acceptable to the metallurgist:--

                                 Treatment of    Process of

                                {1. Pure ores  } Pesey, Spain,
                                {              } &c.
                                {
                                {2. Ores mixed } England, in
                                {   with saline} general.
                                {   gangues.   }
                                {
                                {3. Ores mixed { Viconago in
                                {   with earthy{ Italy, and
                {       A       {   gangues.   { Redruth in
                { De-sulphura-  {              { Cornwall.
                { tion by       {
                { roasting.     {4. Ores mixed }
                {               {   with sever-} Combined with
                {               {   al sul-    } the above.
                {               {   phurets.   }
  I. Class.     {               {
  Treated in    {               {5. Ores with  }
  reverberatory {               {   earthy sa- }
  furnaces.     {               {   line, and  }
                {               {   sulphurous }
                {               {   gangues.   }
                {
                {               {6. Ores with  }
                {       B       {   mattes, as } Vienne, Poul-
                { De-sulphura-  {   at Vienne, } laouen, and
                { tion by iron. {   in Dauphi- } Tarnowitz.
                                {   ny.        }

                                {7. Ores pro-  { Mattes, with  }Many
                                {   ducing     { raw lead.     }places.
                                {   slags of   } Workable lead,{
                {       A       {   various    } without       {Villefort.
                { Founding after{   silicates. } mattes.       {
                { roasting in a {
                { heap, or in a {8. Ores pro-  { Mattes and    }Several
  II. Class.    { reverberatory.{   ducing com-{ workable lead.}places.
  Treated in    {               {   pound sili-{ Workable      {Pont Gibaud
  the mill-slag-{               {   cate slags.{ lead.         {and Scotch
  hearth, the   {               {              {               {furnace.
  _fourneau à_  {
  _manche_, or  {        B      }9. Ores pro-  { Mattes and    }Baad-Ems,
  Scotch fur-   { Founding with }   ducing     { workable      }Hartz,
  nace.         { direct de-    }   slags com- { lead.         }Tarnowitz.
                { sulphuration  }   posed of   } Poor mattes   {
                { by metallic   }   silicates  } and workable  {Tarnowitz.
                { iron.         }   and sub-   } lead.         {
                {               }   silicates. }
                {

The annual production of lead in Europe may be estimated at about 80,000
tons; of which four-sevenths are produced in England, two-sevenths in
Spain, the remainder in Germany and Russia. France does not produce more
than one five-hundredth part of the whole; and only one-fiftieth of its
consumption.

See LITHARGE, MINIUM, or _Red Lead_, SOLDER, SUGAR or _Acetate_ of LEAD,
TYPE METAL, and WHITE LEAD.


LEAD-SHOT; (_Plomb de chasse_, Fr.; _Schrot_, _Flintenschrot_, Germ.)
The origin of most of the imperfections in the manufacture of lead-shot
is the too rapid cooling of the spherules by their being dropped too hot
into the water, whereby their surfaces form a solid crust, while their
interior remains fluid, and in its subsequent concretion, shrinks, so as
to produce the irregularities of the shot.

The patent shot towers originally constructed in England obviate this
evil by exposing the fused spherules after they pass through the
cullender, to a large body of air during their descent into the water
tub placed on the ground. The greatest erection of this kind is probably
at Villach in Carinthia, being 240 Vienna, or 249 English feet high.

The quantity of arsenic added to the mass of melted lead, varies
according to the quality of this metal; the harder and less ductile the
lead is, the more arsenic must be added. About 3 pounds of either white
arsenic or orpiment is enough for one thousand parts of soft lead, and
about 8 for the coarser kinds. The latter are employed preferably for
shot, as they are cheaper and answer sufficiently well. The arsenical
alloy is made either by introducing some of this substance at each
melting; or by making a quantity of the compound considerably stronger
at once, and adding a certain portion of this to each charge of lead. If
the particles of the shot appear lens-shaped, it is a proof that the
proportion of arsenic has been too great; but if they are flattened upon
one side, if they are hollowed in their middle, called _cupping_ by the
workman, or drag with a tail behind them, the proportion of arsenic is
too small.

The following is the process prescribed by the patentees, Ackerman and
Martin. Melt a ton of soft lead, and sprinkle round its sides in the
iron pot, about two shovelfuls of wood ashes, taking care to leave the
centre clear; then put into the middle about 40 pounds of arsenic to
form a rich alloy with the lead. Cover the pot with an iron lid, and
lute the joints quickly with loam or mortar to confine the arsenical
vapours, keeping up a moderate fire to maintain the mixture fluid for
three or four hours; after which skim carefully, and run the alloy into
moulds to form ingots or pigs. The composition thus made is to be put in
the proportion of one pig or ingot into 1000 pounds of melted ordinary
lead. When the whole is well combined, take a perforated skimmer and let
a few drops of it fall from some height into a tub of water. If they do
not appear globular, some more arsenical alloy must be added.

Lead which contains a good deal of pewter or tin must be rejected,
because it tends to produce elongated drops or tails.

From two to three tons are usually melted at once in the large
establishments. The surface of the lead gets covered with a crust of
oxide of a white spongy nature, sometimes called _cream_ by the workmen,
which is of use to coat over the bottom of the cullender, because
without such a bed the heavy melted lead would run too rapidly through
the holes for the granulating process, and would form oblong spheroids.
The mounting of this filter, or lining of the cullender, is reckoned to
be a nice operation by the workmen, and is regarded usually as a
valuable secret.

The cullenders are hollow hemispheres of sheet iron about 10 inches in
diameter, perforated with holes, which should be perfectly round and
free from burs. These must be of an uniform size in each cullender; but
of course a series of different cullenders with sorted holes for every
different size of lead shot, must be prepared. The holes have nearly the
following diameters for the annexed numbers of shot.

  No. 0.    1/50 of an inch.
      1.    1/58     --
      2.    1/66     --
      3.    1/72     --
      4.    1/80     --

From No. 5. to No. 9. the diameter decreases by regular gradations, the
latter being only 1/360 of an inch.

The operation is always carried on with three cullenders at a time;
which are supported upon projecting grates of a kind of chafing dish
made of sheet iron somewhat like a triangle. This chafing dish should be
placed immediately above the fall; while at its bottom there must be a
tub half filled with water for receiving the granulated lead. The
cullenders are not in contact, but must be parted by burning charcoal in
order to keep the lead constantly at the proper temperature, and to
prevent its solidifying in the filter. The temperature of the lead bath
should vary with the size of the shot; for the largest, it should be
such that a bit of straw plunged into it will be scarcely browned, but
for all it should be nicely regulated. The height from which the
particles should be let fall varies likewise with the size of the shot;
as the congelation is the more rapid, the smaller they are. With a fall
of 33 yards or 100 feet, from No. 4. to No. 9. may be made; but for
larger sizes, 150 feet of height will be required.

Every thing being arranged as above described, the workman puts the
filter-stuff into the cullender, pressing it well against the sides. He
next pours lead into it with an iron ladle, but not in too great
quantity at a time, lest it should run through too fast. The shot
thereby formed and found in the tub are not all equal.

The centre of the cullender being less hot affords larger shot than the
sides, which are constantly surrounded with burning charcoal.
Occasionally, also, the three cullenders employed together may have
holes of different sizes, in which case the tub may contain shot of very
various magnitudes. These are separated from each other by square sieves
of different fineness, 10 inches broad and 16 inches long, their bottoms
being of sheet iron pierced with holes of the same diameters as those of
the cullenders. These sieves are suspended by means of two bands above
boxes for receiving the shot; one sieve being usually set above another
in consecutive numbers, for instance 1 and 2. The shot being put into
the upper sieve, No. O. will remain in it, No. 1. will remain in the
lower sieve, and No. 2. will, with all the others, pass through it into
the chest below. It is obvious that by substituting sieves of successive
fineness, shot of any dimension may be sorted.

In the preceding process the shot has been sorted to size; it must next
be sorted to form, so as to separate all the spheroids which are not
truly round, or are defective in any respect. For this purpose a board
is made use of about 27 inches long and 16 broad, furnished partially
with upright ledges; upon this tray a handful or two of the shot to be
sorted being laid, it is inclined very slightly, and gently shaken in
the horizontal direction, when the globular particles run down by one
edge, into a chest set to receive them, while those of irregular forms
remain on the sides of the tray, and are reserved to be re-melted.

After being sorted in this way, the shot requires still to be smoothed
and polished bright. This object is effected by putting it into a small
octagonal cask, through a door in its side, turning upon a horizontal
iron axis, which rests in plummer boxes at its ends, and is made to
revolve by any mechanical power. A certain quantity of plumbago or black
lead is put in along with the shot.


LAZULITE (Eng. and Fr.; _Lazulith_, Germ.); is a blue vitreous mineral,
crystallizing in rhomboidal dodecahedrons; spec. grav. 2·76 to 2·94;
scratches glass; affords a little water by calcination; fusible into a
white glass; dissolves in acids with loss of colour; solution leaves an
alkaline residuum, after being treated with carbonate of ammonia,
filtered, evaporated, and calcined. It consists of silica, 35·8;
alumina, 34·8; soda, 23·2; sulphur, 3·1; carbonate of lime, 3·1. This
beautiful stone affords the native _ultramarine_ pigment, which was very
costly till a mode of making it artificially was lately discovered. See
ULTRAMARINE.


LEATHER, (_Cuir_, Fr.; Germ., _Leder_); is the skin of animals, so
modified by chemical means as to have become unalterable by the external
agents which tend to decompose it in its natural state. The preparation
in a rude manner of this valuable substance, has been known from the
most antient times, but it was not till the end of the last, and the
beginning of the present century, that it began to be manufactured upon
right principles, in consequence of the researches of Macbride, Deyeux,
Seguin, and Davy. There are several varieties of leather; such as sole
leather, boot or upper leather, shamoy leather, kid or glove leather,
&c. Skins may be converted into leather either with or without their
hairy coat.

We shall treat first of sole and upper leathers, being the most
important, and most costly and difficult to prepare in a proper manner.
These kinds consist of organized fibrous gelatine or skin, combined with
the proximate vegetable principle, tannin, and probably also some
vegetable extractive. Under the articles GALLS and TANNIN, will be found
an account of the properties of this substance, and the means of
obtaining it in a state of purity. Calf leather quickly tanned by an
infusion of galls, consists of 61 parts of skin, and 39 of vegetable
matter in 100 by weight; by solution of catechu, it consists of 80 of
skin, and 20 of vegetable matter; by infusion of Leicester willow, of
74·5 skin, and 25·5 vegetable matter; and by infusion of oak bark, of
73·2 skin, and 26·8 vegetable matter. By the slow process of tanning,
continued for three months, the increase of weight upon the skin in its
conversion into leather, is greatly less; the vegetable constituents
being from Leicester willow only 13 per cent. of the leather, and from
oak bark 15 per cent. Sole leather, however, generally contains no less
than 40 per cent. of vegetable matter. In every astringent bark, the
inner white part next to the _alburnum_, contains the largest quantity
of tannin, and the middle coloured part contains most extractive matter.
The outer surface or epidermis seldom furnishes either tannin or
extractive matter. Young trees abound most in the white cortical layers,
and are hence more productive of tannin under equal weights, than the
barks of old trees. In no case is there any reason to believe that the
gallic acid of astringent vegetables is absorbed in the process of
making leather; hence Seguin’s theory of the agency of that substance in
disoxygenating skin, falls to the ground. The different qualities of
leather made with the same kind of skin, seem to depend very much upon
the different quantities of extractive matter it may have absorbed. The
leather made with infusion of galls, is generally harder and more liable
to crack than the leather obtained from infusions of barks; and it
always contains a much larger proportion of tannin, and a smaller
proportion of extractive matter.

When calf skin is slowly tanned in weak solutions of the bark, or of
catechu, it combines with a good deal of extractive matter, and though
the increase of the weight of the skin be comparatively small, yet it
has become perfectly insoluble in water, forming a soft, but at the same
time a strong leather. The saturated infusions of astringent barks
contain much less extractive matter in proportion to their tannin, than
the weak infusions; and when skin is quickly tanned in the former, it
produces a worse and less durable leather than when slowly tanned in the
latter. In quick tanning, a considerable quantity of vegetable
extractive matter is thus lost to the manufacturer, which might have
been made to enter as a useful constituent into the leather. These
observations show that there is sufficient foundation for the opinion of
the common workmen, concerning what is technically called _feeding_ of
leather, in the slow method of tanning; and though the processes of this
art have been unnecessarily protracted by defective methods of steeping,
and want of progressive infiltration of the astringent liquor through
the skins, yet in general they appear to have arrived, in consequence of
old experience, at a degree of perfection in the quality of the leather,
which cannot be far exceeded by means of any theoretical suggestions
which have been advanced.

On the first view it may appear surprising, that in those cases of quick
tanning, where extractive matter forms a certain portion of the leather,
the increase of weight is less than when the skin is combined with the
pure tannin; but the fact is easily accounted for, when we consider that
the attraction of skin for tannin must be probably weakened by its union
with extractive matter; and whether we suppose that the tannin and
extractive matter enter together into combination with the matter of
skin, or unite with separate portions of it, still, in either case, the
primary attraction of skin for tan must be to a certain extent
diminished.

In examining astringent vegetables in relation to their power of making
leather, it is necessary to take into account not only the quantity they
may contain of the _substance_ precipitable by gelatine, but likewise
the quantity and the nature of the extractive matter; and in cases of
comparison, it is essential to employ infusions of the same degree of
concentration.

Of all astringent substances hitherto examined, catechu is that which
contains the largest proportion of tannin; and in supposing, according
to the usual estimation, that from four to five pounds of common oak
bark are required to produce one pound of leather, it appears, from the
various synthetical experiments, that about half a pound of catechu
would answer the same purpose. Mr. Purkis found, by the results of
different accurate experiments, that 1 pound of catechu was equivalent
to 7 or 8 of oak bark. For the common purposes of the tanner, 1 pound of
it would be equivalent also to 2-1/4 pounds of galls, to 7-1/2 of the
Leicester willow, to 11 of the bark of the Spanish chesnut, to 18 of the
bark of the common elm, to 21 of the bark of the common willow, and to 3
pounds of sumach.

Various menstrua have been proposed for the purpose of expediting and
improving the process of tanning, among others, lime water, and solution
of pearl-ash; but as these two substances form compounds with tannin
which are not decomposable by gelatine, it follows that their effects
must be prejudicial. There is very little reason to suppose that any
bodies will be found which, at the same time that they increase the
solubility of tannin in water, will not likewise diminish its attraction
for skin.

In this country all tanned leather is distinguished into two kinds,
called _hides_ and _skins_; the former term being appropriated to that
made from the larger animals, as bulls, buffaloes, oxen, and cows, into
thick strong sole leather; and the latter to that made from calves,
seals, &c., into thinner and more flexible upper leather. Sometimes the
hides are brought into the market merely dried, as from Buenos-Ayres; or
dried and salted, as from Bahia and Pernambuco; but the greater part are
fresh from recently slaughtered animals. The heaviest ox hides are
preferred for forming _butts_ or _backs_, which are manufactured as
follows:--

The washing process must be more or less elaborate, according to the
state of the skins. Those that are salted and dry require to be steeped,
beaten, and rubbed several times alternately, to bring them to the fresh
condition.

After removing the horns, the softened or recent hides are laid in a
heap for two or three days, after which they are suspended on poles in a
close room called a smoke-house, heated somewhat above the common
temperature by a smouldering fire. In these circumstances, a slight
putrefaction supervenes, which loosens the epidermis, and renders the
hair easily detachable by the _fleshing_ knife; a large two-handled
implement, with a blunt edge, and bent to suit the curvature of the
rounded beam of the wooden horse upon which the hide is scraped. See
CURRYING.

The next step is immersion in a pit containing water impregnated with
about a 1000th part of sulphuric acid. This process is called _raising_,
because it distends the pores, and makes the fibres swell, so as to
render the skins more susceptible of the action of the tanning
infusions. Forty-eight hours in general suffice for this operation, but
more time may be safely taken.

When the hides are found to be sufficiently raised, they are transferred
to a pit, in which they are stratified with oak bark, ground by a proper
mill into a coarse powder. The pit is then filled up with an infusion of
oak bark called ooze, and the hides are allowed to remain in it for
about a month or six weeks. By this time the tannin and extractive
matter of the bark having combined intimately with the animal fibre, the
pit is exhausted of its virtue, and must be renewed, by taking out the
spent bark, and subjecting the skins to a fresh dose of oak bark and
ooze. The hides which were placed near the top of the first pit, must be
placed near the bottom of the next. In this mixture they remain, upon
the old practice, about three months. The last process being repeated
twice or thrice, perfectly tanned leather is the result. The hides are
now removed from the pit, and hung up in a shed. In the progress of
drying, which should be slow, they are compressed with a steel tool, and
beaten smooth, to render them more firm and dense.

Some manufacturers place on the bottom of the pit 5 or 6 inches of spent
bark, over it 2 inches of fresh bark, then a skin; and so, alternately,
a layer of new bark and a skin, till the pit is nearly full, reserving a
small space at top for a thicker layer of bark, over which weighted
boards are laid, to condense the whole down into the tanning infusion.

The operation of tanning sole leather in the above way, lasts a year or
a year and a half, according to the quality wanted, and the nature of
the hides.

A perfect leather is recognized by its section, which should have a
glistening marbled appearance, without any white streaks in the middle.

_Crop hides_ are manufactured by immersion, during three or four days,
in pits containing milk of lime; in which they are occasionally moved up
and down in order to expose them equally to the action of this
menstruum. They are then removed, and cleared from hair and impurities,
by using the fleshing knife upon the horse; after which they must be
completely freed from the lime by a thorough washing. They are next
plunged in pits containing a weak ooze or infusion of oak bark, from
which they are successively transferred into other pits with stronger
ooze; all the while being daily _handled_, that is, moved up and down in
the infusion. This practice is continued for about a month or six weeks.
They are now ready to be subjected to a mixture of ground oak bark and
stronger ooze in other pits, to a series of which they are progressively
subjected during two or three months.

The hides are next put into large vats, called _layers_, in which they
are smoothly stratified with more oak bark, and a stronger infusion of
it. After six weeks they are taken out of these vats, and subjected to a
new charge of the same materials for two months. This simple process is
repeated twice or thrice, at the option of the manufacturer, till the
hides are thoroughly tanned. They are then slowly dried, and condensed
in the manner above described. These crop hides form the principal part
of the sole leather used for home consumption in England.

The process of tanning _skins_ (as of calves, seals, &c.) is in some
respects peculiar. They are left in the lime pits for about twelve days,
when they are stripped of their hair, washed in water, then immersed in
a lixivium of pigeons’ dung, called a _grainer_, of an alkaline nature.
Here they remain from eight to ten days, according to the state of the
atmosphere, during which time they are frequently handled, and scraped
on both sides upon a convex wooden beam. This scraping or _working_, as
it is termed, joined to the action of the _grainer_, serves to separate
the lime, oil, and glutinous matter, and to render the skin pliant,
soft, and ready to imbibe the tanning principle. They are with this view
transferred into pits containing a weak solution of bark, in which they
undergo nearly the same treatment as described above for _crop_ hides;
but they are not commonly stratified in the layers. The time occupied in
tanning them is usually limited to three months. They are then dried,
and disposed of to the currier, who dresses and blackens them for the
upper leathers of boots and shoes, for harness, and other purposes. The
light and thin sorts of cow and horse hides are often treated like calf
skins.

In all the above processes, as the animal fibres on the surface of the
skin absorb most readily the tanning principles, and thereby obstruct,
in a certain degree, their passage into the interior fibres, especially
of thick hides, it becomes an object of importance to contrive some
method of overcoming that obstacle, and promoting the penetration of the
tan. The first manufacturer who appears to have employed efficacious
mechanical means of favouring the chemical action was Francis G.
Spilsbury, who in April, 1823, obtained a patent for the following
operation:--After the hides are freed from the hairs, &c. in the usual
way, they are minutely inspected as to their soundness, and if any holes
be found, they are carefully sewed up, so as to be water tight. Three
frames of wood are provided of equal dimensions, fitted to each other,
with the edges of the frames held together by screw bolts. A skin about
to be tanned is now laid upon the frame, and stretched over its edges,
then the second frame is to be placed upon it, so that the edges of the
two frames may pinch the skin all round and hold it securely; another
such skin is then stretched over the upper surface of the second frame,
in like manner, and a third frame being set upon this, confines the
second skin. The three frames are then pinched tightly together by a
series of screw bolts, passing through ears set round their outer edges,
which fix the skin in a proper manner for being operated upon by the
tanning liquor.

A space has been thus formed between the two skins, into which, when the
frames are set upright, the infusion is introduced by means of a pipe
from the cistern above, while the air is permitted to escape by a
stopcock below. This cock must of course be shut whenever the bag is
filled, but the one above is left open to maintain a communication with
the liquor cistern, and to allow the hydrostatic pressure to force the
liquor through the cutaneous pores by a slow infiltration, and thus to
bring the tannin into contact with all the fibres indiscriminately. The
action of this pressure is evinced by a constant perspiration on the
outer surfaces of the skins.

When the tanning is completed, the upper stopcock is closed, and the
under is opened to run off the liquor. The frames are now removed, the
bolts are unscrewed, and the pinched edges of the skins pared off; after
which they are to be dried and finished in the usual manner.

A modification of this ingenious and effectual process was made the
subject of a patent, by William Drake, of Bedminster, tanner, in
October, 1831. The hides, after the usual preparatory processes, are
immersed in a weak tan liquor, and by frequent handling or turning over,
receive an incipient tanning before being submitted to the infiltration
plan. Two hides, as nearly of the same size and shape as possible, are
placed grain to grain, when their corresponding edges are sewed firmly
together all round by shoemaker’s waxed thread, so as to form a bag
sufficiently tight to hold tan liquor. This bag must then be suspended
by means of loops sewed to its shoulder end, upon pegs, in such a manner
that it may hang within a wooden-barred rack, and be confined laterally
into a book form. About an inch of the bag is left unsewed at the upper
end, for the purpose of introducing a funnel through which the cold tan
liquor is poured into the bag till it be full. After a certain interval
which varies with the quality of the hides, the outer surface becomes
moist, and drops begin to form at the bottom of the bag. These are
received in a proper vessel, and when they accumulate sufficiently may
be poured back into the funnel; the bag being thus, as well as by a
fresh supply from above, kept constantly distended.

When the hides are observed to feel hard and firm, while every part of
them feels equally damp, the air of the tanning apartment having been
always well ventilated, is now to be heated by proper means to a
temperature gradually increasing from 70° to 150° of Fahrenheit’s scale.
This heat is to be maintained till the hides become firmer and harder in
all parts. When they begin to assume a black appearance in some parts,
and when the tan liquor undergoes little diminution, the hides may be
considered to be tanned, and the bag may be emptied by cutting a few
stitches at its bottom. The outer edges being pared off, the hides are
to be finished in the usual way. During their suspension within the
racks, the hides should be shifted a little sideways, to prevent the
formation of furrows by the bars, and to facilitate the equable action
of the liquor.

By this process the patentee says, that a hide may be tanned as
completely in ten days as it could be in ten months by the usual method.
I have seen a piece of sole leather thus rapidly tanned, and it seemed
to be perfect. How it may wear, compared with that made in the old way,
I cannot pretend to determine.

Messrs. Knowlys and Duesbury obtained a patent in August, 1826, for
accelerating the impregnation of skins with tannin, by suspending them
in a close vessel, from which the air is to be extracted by an air pump,
and then the tanning infusion is to be admitted. In this way, it is
supposed to penetrate the hide so effectually as to tan it uniformly in
a short time.

About 32 years ago, a similar vacuum scheme was employed to impregnate
with weaver’s paste or starch, the cops of cotton weft, for the dandy
looms of Messrs. Radcliff and Ross, of Stockport.

Danish leather is made by tanning lamb and kid skins with willow bark,
whence it derives an agreeable smell. It is chiefly worked up into
gloves.

_Of the tawing or dressing of skins for gloves, and white sheep
leather._

The operations of this art are: 1. washing the skins; 2. properly
treating them with lime; 3. taking off the fleece; 4. treatment in the
leather steep.

A shed erected upon the side of a stream, with a cistern of water for
washing the skins; wooden horses for cleaning them with the back of the
fleshing knife; pincers for removing the fibres of damaged wool; a
plunger for depressing the skins in the pits; a lime pit; a pole with a
bag tied to the end of it; a two-handed fleshing knife; a rolling pin,
from 15 to 18 inches long, thickened in the middle; such are some of the
utensils of a tawing establishment. There must be provided also a table
for applying the oil to the skins; a fulling mill, worked by a
water-wheel or other power; a dressing peg; a press for squeezing out
the fatty filth; a stove; planks mounted upon legs, for stretching the
skins, &c.

Fresh skins must be worked immediately after being washed, and then
dried, otherwise they ferment, and contract either indelible spots, or
get tender in certain points, so as to open up and tear under the tools.
When received in the dry state they should be steeped in water for two
days, and then treated as fresh skins. They are next strongly rubbed on
the convex horse-beam with a round-edged knife, in order to make them
pliant. The rough parts are removed by the fleshing knife. One workman
can in this way prepare 200 skins in a day.

The flesh side of each being rubbed with a cold cream of lime, the skins
are piled together with the woolly side of each pair outermost, and the
flesh sides in contact. They are left in this state for a few days, till
it is found that the wool may be easily removed by _plucking_.

They are next washed in running water, to separate the greater part of
the lime, stripped of the wool by small spring tweezers, and then
fleeced smooth by means of the rolling-pin, or sometimes by rubbing with
a whetstone. Unless they be fleeced soon after the treatment with lime,
they do not well admit of this operation subsequently, as they are apt
to get hard.

They are now steeped in the milk of lime-pit, in order to swell, soften,
and cleanse them; afterwards in a weak pit of old lime-water, from which
they are taken out and drained. This steeping and draining upon inclined
tables, are repeated frequently during the space of 3 weeks. Only the
skins of young animals, or those of inferior value are tawed. Sometimes
the wool is left on, as for housings, &c.

The skins, after having been well softened in the steeps, are rubbed on
the outside with a whetstone set in a wooden case with two handles, in
order to smooth them completely by removing any remaining filaments of
wool. Lamb skins are rubbed with the pin in the direction of their
breadth, to give them suppleness; but sheep skins are fulled with water
alone. They are now ready for the _branning_, which is done by mixing 40
lbs. of bran with 20 gallons of water, and keeping them in this
fermentable mixture for three weeks--with the addition, if possible, of
some old bran water. Here they must be frequently turned over, and
carefully watched, as it is a delicate operation. In the course of two
days in summer, and eight in winter, the skins are said to be _raised_,
when they sink in the water. On coming out of the bran, they are ready
for the white stuff; which is a bath composed of alum and sea-salt.
Twelve, fourteen, and sometimes eighteen pounds of alum for 100 skins,
form the basis of the bath; to which two and a half pounds of salt are
added in winter, and three in summer. These ingredients are introduced
into a copper with twelve gallons of water. The salt aids in the
whitening action. When the solution is about to boil, three gallons of
it are passed through the cullender into a basin; in this 26 skins are
worked one after another, and after draining, they are put together into
the bath, and left in it for ten minutes to imbibe the salts. They are
now ready to receive the paste. For 100 skins, from 13 to 15 pounds of
wheat flour are used along with the yolks of 50 eggs. After having
warmed the alum bath through which the skins have been passed, the
flower is dusted into it, with careful stirring. The paste is well
kneaded by the gradual addition of the solution, and passed through the
cullender, whereby it becomes as clear as honey. To this the yolks being
added, the whole is incorporated with much manual labour. The skins are
worked one after another in this paste; and afterwards the whole
together are left immersed in it for a day. They are now stretched and
dried upon poles, in a proper apartment, during from 8 to 15 days,
according to the season.

The effects of the paste are to whiten the skins, to soften them, and to
protect them from the hardening influence of the atmosphere, which would
naturally render them brittle. They would not bear working upon the
_softening iron_, but for the emulsion which has been introduced into
their substance. With this view they are dipped in a tub of clear water
during five or six minutes, and then spread and worked upon the board.
They are increased by this means in length, in the proportion of 5 to 3.
No hard points must be left in them. The whiteness is also better
brought out by this operation, which is performed upon the flesh side.
The softening tool is an iron plate, about one foot broad, rounded over
above, mounted upon an upright beam, 30 inches high, which is fixed to
the end of a strong horizontal plank, 3-1/2 feet long, and 1 broad. This
plank is heavily loaded, to make it immovable upon the floor. Sometimes
the skins are next spread over an undressed clean skin upon the horse,
and worked well with the two-handled knife, for the purpose of removing
the first and second epidermis, called the _fleur_ and _arrière-fleur_
by the French _megissiers_. They are then dried while stretched by hooks
and strings. When dry they are worked on the _stretching iron_, or they
are occasionally polished with pumice stone. A delicate yellow tint is
given by a composition made of two parts of whitening, and one of ochre,
applied in a moistened state, and well worked in upon the grain side.
After being polished with pumice, they are smoothed with a hot iron, as
the laundresses do linen, whereby they acquire a degree of lustre, and
are ready to be delivered to the _glover_.

For _housings_, the best sheepskins are selected, and such as are
covered with the longest and most beautiful fleece. They are steeped in
water, in order to be cleaned and softened; after which they are thinned
inside by the fleshing knife. They are now steeped in an old bran pit
for 3 or 4 days, when they are taken out and washed. They are next
subjected to the white or alum bath, the wool being carefully folded
within; about 18 pounds of alum being used for 100 skins. The paste is
made as for the fleeced skins, but it is merely spread upon their flesh
side, and left upon them for 18 hours, so as to stiffen. They are then
hung up to dry. They are next moistened by sprinkling cold water upon
them, folded up, piled in a heap, and covered with boards weighted with
heavy stones; in which state they remain for two days. They are next
opened with a round iron upon the horse, and subjected to the stretching
iron, being worked broadwise. They are dried with the fleece outermost,
in the sun if possible; and are finished upon the _stretcher_.

Calf and lamb skins with their hair and wool are worked nearly in the
same manner; only the thicker the skin, the stronger the alum bath ought
to be. One pound of alum and one of salt are required for a single calf
skin. It is left four days in this bath, after which it is worked upon
the _stretcher_, then fulled. When half dry the skins are opened upon
the horse. In eight days of ordinary weather, they may be completely
dressed. Lamb skins are sometimes steeped during eight days in a bath
prepared with unbolted rye flour and cold water, in which they are daily
moved about two or three times. They are then dried, stretched upon the
iron, and switched upon the fleecy side.

_Chamois_ or _Shamoy leather_.--The skins are first washed, limed,
fleeced, and branned as above described. They are next _efflowered_,
that is, deprived of their epidermis by a concave knife, blunt in its
middle part, upon the convex horse-beam. The cutting part serves to
remove all excrescences, and to equalize the thickness, while the blunt
part softens and smooths. The skins of goats, does, and chamois are
always treated in this way. They are next subjected to the fermenting
bran steep for one or two days, in ordinary weather; but in hot weather
for a much shorter time, sometimes only moving them in the sour bran
liquor for a few minutes. They are lastly wrung at the peg, and
subjected to the fulling mill.

When the skins have been sufficiently swelled and suppled by the
branning, they may receive the first oil as follows: a dozen skins being
stretched upon the table, the fingers are dipped in the oil, and shaken
over the skins in different places, so as to impart enough of it to
imbue the whole surface slightly, by friction with the palms of the
hands. It is to the outside or _grain_ that the oil is applied. The
skins are folded four together, so as to form balls of the size of a
hog’s bladder, and thrown into the trough of the fulling mill, to the
number of twelve dozen at once. Here they remain exposed to the beater
for two, three, or four hours, according to their nature and the state
of the weather. They are taken out, aired, oiled, and again fulled. The
airing and fulling are repeated several times, with more or less
frequent oilings. Any cheap animal oil is employed.

After these operations, the skins require to be subjected to a
fermenting process, to dilate their pores, and to facilitate their
combination with the oil. This is performed in a chamber only 6 feet
high, and 10 or 12 feet square. Poles are suspended horizontally a few
inches from the ceiling, with hooks fixed in them to which the skins are
attached. A somewhat elevated temperature is maintained, and by a stove
if need be. This operation requires great skill and experience.

The remainder of the epidermis is next removed by a blunt concave knife
and the horse; whereby the surface is not cut, but rather forcibly
scraped.

The skins are now scoured to carry off the redundant oil; which is
effected by a potash lye, at two degrees Baumé, heated no hotter than
the hand can bear. In this they are stirred briskly, steeped for an
hour, and lastly wrung at the peg. The soapy liquor thus expelled is
used for inferior purposes. The clean skins after being dried, are
finished first on the _stretcher-iron_, and then on the _herse_ or
stretching frame.

_Leather of Hungary._--This is manufactured by impregnating strong hides
with alum, common salt, and suet; by a rapid process which is usually
completed in the space of two months. The workshop is divided into two
parts; 1. a shed on the side of a stream, furnished with wooden horses,
fleshing knives, and other small tools. In one corner is a furnace with
a boiler for dissolving the alum, a vat for immersing the hides in the
solution, and several subsidiary tubs. 2. A chamber, 6 feet high, by 15
feet square, capable of being made very tight, for preserving the heat.
In one corner is a copper boiler, of sufficient size to contain 170
pounds of tallow. In the middle of the stove is a square stone slab,
upon which an iron grate is placed about a yard square. This is covered
with charcoal. At each side of the stove are large tables, which occupy
its whole length, and on which the leather is spread to receive the
grease. The upper part below the ceiling is filled with poles for
hanging the leather upon to be heated. The door is made to shut
perfectly close.

The first operations are analogous to those of tanning and tawing; the
skins being washed, cut in halves, shaved, and steeped for 24 hours in
the river. They are then cleaned with 5 or 6 pounds of alum, and 3-1/2
pounds of salt, for a piece of hide which weighs from 70 to 80 pounds.
The common salt softens the effect of the alum, attracts the moisture of
the air, and preserves the suppleness of the skin. When the alum and
salt are dissolved, hot water is poured upon the hides placed in a vat,
and they are tramped upon by a workman walking repeatedly from one end
of the vat to the other. They are then transferred into a similar vat
containing some hot water, and similarly tramped upon. They are next
steeped for eight days in alum water. The same round of operations is
repeated a second time.

The skins are now dried either in the air, or a stove room; but before
being quite dry, they are doubled together, well stretched to take out
the wrinkles, and piled up. When dry, they are again tramped to open the
pores as well as to render the skin pliant, after which they are
whitened by exposure to the sun.

Tallow of inferior quality is employed for greasing the leather. With
this view the hides are hung upon the poles in the close stove room,
then laid upon the table, and besmeared with the tallow melted till it
begins to crackle. This piece is laid on another table, is there covered
with a second, similarly greased, and so forth. Three pounds of fat are
commonly employed for one piece of leather.

When the thirty strips, or fifteen hides passed through the grease in
one operation are completed, two workmen take the first piece in their
hands, and stretch it over the burning charcoal on the grate for a
minute, with the flesh side to the fire. The rest are passed over the
flame in like manner. After _flaming_, the pieces are successively laid
on an inclined table exposed to the fire, where they are covered with a
cloth. They are finally hung upon poles in the air to dry; and if the
weather be warm, they are suspended only during the night, so as to
favour the hardening of the grease. Instead of the alum bath, M.
Curaudau has employed with advantage a steep of dilute sulphuric acid.

_Morocco leather._--The true morocco leather is goat skin tanned and
then dyed on the side of the grain. Sheep skins are treated in the same
way. The skins are steeped first in a fermenting mixture of bran water
for a few days, they are then worked upon the horse, steeped in fresh
water for 12 hours, and rinsed in the same. They are next drained,
steeped in weak lime pits for a proper time, till the hairs can be
readily detached. They are now subjected to the action of a blunt knife
upon the horse-beam, in order to strip off their hair, after which they
are cleansed in running water. Any excrescences must be carefully
removed with the fleshing knife, and their edges neatly pared. The next
process is rubbing them strongly with a piece of hard schist, set in a
wooden frame, in order to expel by the pressure any lime which may still
adhere, and to soften the grain. They are now worked upon the horse-beam
with the blunt knife, and subjected to a species of fulling, by being
agitated by pegs in a revolving cask along with water. Many
manufacturers prefer a weak alkaline lye, or putrified urine, to the
lime bath.

The skins are immersed for a night and a day, in a bran bath, in a
certain state of fermentation, then worked on the horse, and salted, to
preserve them till they are to be dyed.

Preparatory to being dyed, each skin is sewed together edgewise, with
the grain on the outside, and it is then mordanted either with a
solution of tin, or with alum water. The colour is given by cochineal,
of which from 10 to 12 ounces are required for a dozen of skins. The
cochineal being boiled in water along with a little tartar or alum for a
few minutes, forms a red liquor, which is filtered through a linen
cloth, and put into a clean cask. The skins are immersed in this bath,
and agitated in it for about half an hour; they are taken out and
beaten, and then subjected to a second immersion in the cochineal bath.
After being thus dyed, they are rinsed and tanned with Sicilian sumach,
at the rate of two pounds for a skin of moderate size. This process is
performed in a large tub made of white wood, in the liquor of which the
skins are floated like so many bladders, and moved about by manual
labour during four hours. They are then taken out, drained, and again
subjected to the tanning liquor; the whole process requiring a space of
twenty-four hours. The skins are now unstitched, rinsed, fulled with
beetles, drained, rubbed hard with a copper blade, and lastly hung up to
dry.

Some manufacturers brighten the colour by applying to the surface of the
skins, in a damp state, a solution of carmine in ammonia with a sponge;
others apply a decoction of saffron to enliven the scarlet tint. At
Paris the morocco leather is tanned by agitation with a decoction of
sumach in large casks made to revolve upon a horizontal axis, like a
barrel churn. White galls are sometimes substituted for sumach; a pound
being used for a skin. The skins must be finally cleaned with the utmost
care.

The black dye is given by applying with the brush a solution of red
acetate of iron to the grain side. Blue is communicated by the common
cold indigo vat; violets, with a light blue followed by cochineal red;
green, by Saxon blue followed by a yellow dye, usually made with the
chopped roots of the barberry. This plant serves also for yellows. To
dye olive, the skins are first passed through a weak solution of green
vitriol, and then through the decoction of barberry root, containing a
little Saxon blue. Puce colour is communicated by logwood with a little
alum; which may be modified by the addition of a little Brazil wood. In
all these cases, whenever the skins are dyed, they should be rinsed,
wrung or rather drained, stretched upon a table, then besmeared on the
grain side with a film of linseed oil applied by means of a sponge, in
order to promote their glossiness when curried, and to prevent them
becoming horny by too rapid drying.

The last process in preparing morocco leather is the currying, which
brings out the lustre, and restores the original suppleness. This
operation is practised in different manners, according to the purpose
the skins are to serve. For pocket-books, portfolios, and case-making in
general, they must be thinned as much as possible upon the flesh side,
moistened slightly, then stretched upon the table, to smooth them; dried
again, moistened, and lastly passed two or three times through the
cylinder press in different directions, to produce the crossing of the
grain. The skins intended for the shoemaker, the saddler, the
bookbinder, &c., require more pliancy, and must be differently curried.
After being thinned, they are glazed with a polisher while still moist,
and a grain is formed upon the flesh side with the roughened lead plate
or grainer of the curriers, called in French _pommelle_; they are glazed
anew to remove the roughness produced by the pommel, and finally grained
on the flesh side with a surface of cork applied under a pommel of white
wood.

_Russia leather._--The Russians have long been possessed of a method of
making a peculiar leather, called by them _jucten_, dyed red with the
aromatic saunders wood. This article has been much sought after, on
account of not being subject to mould in damp situations, being proof
against insects, and even repelling them from the vicinity of its odour.
The skins are freed from the hair or fleece, by steeping in an ash-lye
too weak to act upon the animal fibres. They are then rinsed, fulled for
a longer or shorter time according to their nature, and fermented in a
proper steep, after having been washed in hot water. They are taken out
at the end of a week, but they may be steeped a second time if deemed
necessary, to open their pores. They are now cleaned by working them at
the horse on both the flesh and grain sides.

A paste is next composed, for 200 skins, of 38 pounds of rye flour,
which is set to ferment with leaven. This dough is worked up with a
sufficient quantity of water to form a bath for the skins, in which they
are soaked for 48 hours; they are then transferred into small tubs,
where they remain during fifteen days, after which they are washed at
the river. These operations serve to prepare the skins for absorbing the
astringent juices with uniformity. A decoction of willow bark (_salix
cinerea_, and _salix caprea_) being made, the skins are immersed in the
boiler whenever the temperature of the liquor is sufficiently lowered
not to injure the animal fibres, and handled and pressed for half an
hour. This manipulation is repeated twice daily during the period of a
week. The tanning infusion is then renewed, and applied to the same
skins for another week; after which being exposed to the air to dry,
they are ready for being dyed, and then curried with the empyreumatic
oil of the bark of the birch tree. To this substance the Russia leather
owes its peculiarities. Many modes have been prescribed for preparing
it; but the following is the one practised in Russia.

The whitish membranous epidermis of the birch, stripped of all woody
parts, is introduced into an iron boiler, which, when stuffed full, is
covered tight with a vaulted iron lid, having a pipe rising from its
centre. A second boiler into which this pipe passes without reaching its
bottom, is set over the first, and is luted to it at the edges, after
the two are bolted together. They are then inverted, so that the upper
one contains the birch bark. The under half of this apparatus is sunk in
the earth, the surface of the upper boiler is coated over with a clay
lute, then surrounded with a fire of wood, and exposed to a red heat,
till the distillation be completed. This operation, though rude in
appearance, and wasteful of wood, answers its purpose perfectly well.
The iron cylinder apparatus used in Britain for distilling wood vinegar,
would, however, be much more convenient and productive. When the above
boilers are unluted, there is found in the upper one a very light powder
of charcoal, and in the under one which served as a receiver, there is
an oily, brown, empyreumatic fluid, of a very strong smell, which is
mixed with the tar, and which floats over a small quantity of crude
vinegar. The former matter is the oil employed to impregnate the skins,
by working it into the flesh side with the curriers’ tools. It is
difficult to make this oil penetrate with uniformity; and the Russians
do not always succeed in this process, for they turn out many skins in a
spotted state. This oil is at present obtained in France by distilling
the birch bark in copper stills, and condensing the products by means of
a pipe plunged in cold water. About 60 per cent. of the weight of the
bark is extracted.

The skins imbibe this oil most equally before they are fully dry. Care
must be taken not to apply too much of it, for fear of its passing
through and staining the grain-side of the leather. Chevreul has
investigated the chemical nature of this odoriferous substance, and
finding it to be a peculiar compound, has called it _betuline_.


LEDUM PALUSTRE. This plant is employed in Russia to tan the skins of
goats, calves, and sheep, into a reddish leather of an agreeable smell;
as also in the preparation of the oil of birch, for making what is
commonly called Russia leather.


LEGUMINE, is the name of a vegeto-alkali supposed to exist in leguminous
plants.


LEMONS. See CITRIC ACID, and OILS, ESSENTIAL.


LEVIGATION, is the mechanical process whereby hard substances are
reduced to a very fine powder.


LEUCITE, is a hard Vesuvian mineral, consisting of silica, 54; alumina,
23; potash, 23.


LEUCINE, is a white crystalline substance produced by acting upon flesh
with sulphuric acid.


LEWIS, is the name of one kind of shears used in cropping woollen cloth.


LIAS, is a fine-grained argillaceous limestone, whose geological
position is under the oolite; it is the proper lithographic stone.


LIBAVIUS, LIQUOR OF, is the bichloride of tin, prepared by dissolving
that metal with the aid of heat, in _aqua regia_, or by passing chlorine
gas through a solution of muriate of tin till no more gas be absorbed,
evaporating the solution, and setting it aside to crystallize. The
anhydrous bichloride is best prepared by mixing four parts of corrosive
sublimate with one part of tin, previously amalgamated with just so much
mercury as to render it pulverizable; and by distilling this mixture
with a gentle heat. A colourless fluid, the dry bichloride of tin, or
the proper fuming liquor of Libavius, comes over. When it is mixed with
one-third of its weight of water it becomes solid. The first bichloride
of tin is used in calico-printing.


LICHEN. See ARCHIL.


LIGNEOUS MATTER, is vegetable fibre. See FIBROUS MATTER.


LIGNITE, is one of the most recent geological formations, being the
carbonaceous remains of forest trees. From this substance, as found in
the neighbourhood of Cologne, the brown colours, called _umber_ and
_earth of Cologne_, are prepared.


LILAC DYE. See CALICO-PRINTING AND DYEING.


LIMESTONE (_Calcaire_, Fr.; _Kalkstein_, Germ.); may be classed under
the following heads:--

1. _Calcareous spar_ occurs in colourless crystals or crystalline
masses; dissolves with effervescence in muriatic acid; is scratched by
soft iron, but not by the nail; specific gravity 2·7; loses 46 per cent.
by the expulsion of carbonic acid, and calcines into quicklime.

2. _Calcsinter_, _or stalactitic carbonate of lime_, called also
concretionary limestone, because formed of zones more or less undulated,
and nearly parallel. These zones have a fibrous structure, arising from
the successive deposits of the crystalline limestone from its solvent
water. The long conical pieces called stalactites, show fibres
converging to the axis. The tubercular consists of irregular lumps often
sprinkled over with small crystals, and associated so as to exhibit the
appearance of cauliflower. The stratiform, commonly called stalagmite,
or alabaster limestone, represents zones not concentric, but spread out,
waving, and parallel; its texture is sometimes lamellar, and sometimes
fibrous. These waving strata are distinguishable from one another by
their different densities, and by their degrees of translucency. This
stalagmitic mass bears the name of oriental alabaster, when it is
reddish-yellow with distinct zones, and is susceptible of a fine polish.
Stalactites are formed in the large excavations of calcareous rocks. The
water percolating down through them, and dropping from the roofs of the
caverns, is usually charged with carbonate of lime held in suspension by
an excess of carbonic acid. The exposure to air, the motion, and the
consequent diminution of pressure, cause the precipitation of the
carbonate of lime in the solid state. Each drop of water, on falling
through the vault, abandons a small film of limestone, which enlarges by
degrees, and forms either a cylinder or solid mass. This alabaster
differs from marble in its parallel and waving layers, and its faint
degree of transparency.

This alabaster serves for the decoration of public buildings, and is
occasionally introduced into certain pieces of furniture. The fine
Egyptian alabaster was anciently brought from the mountains of the
Thebaid, between the Nile and the Red Sea, near a town called
Alabastron, whence probably the name. Very fine red alabaster, of great
hardness, was found at one time in the quarries of Montmartre, but the
stock was soon exhausted.

_The incrusting concretionary limestone_ differs little from the
preceding except in the rapidity of its formation, and in being moulded
upon some body whose shape it assumes. These deposits from calcareous
springs, form equally on vegetable bodies, on stones, metals, within
pipes of cast iron, wood, or lead. The incrustations on vegetable and
animal substances are vulgarly called petrifactions, as the organic
fibres are replaced by stone. One of the most curious springs of this
nature is at the baths of Saint Philip, in Tuscany, where the water
flows in almost a boiling state, over an enormous mass of alabaster
which it has produced. The carbonate of lime seems to be held in
solution here by sulphuretted hydrogen, which flies off when the water
issues to the day. Dr. Vegny has taken advantage of this property of the
spring, to obtain basso-relievo figures of great whiteness and solidity.
He makes use of sulphur moulds.

_Calcareous tuf_ consists of similar incrustations made by petrifying
rivulets running over mud, sand, vegetable remains, &c. It is porous,
even cellular, somewhat soft, impure, and of a dirty gray colour. Its
surface is wavy, rough, and irregular. These incrustations or deposits
are, however, sometimes so abundant, and the resulting stony matters so
hard that buildings may be constructed with them. The stone with which
the town of Pasti, in Italy, is built has been called _pipe-stone_ by
the Italians; and it has apparently derived its origin from
incrustations upon large reeds.

The _travertino_, which served to construct all the monuments of Rome,
appears to have been formed by the deposits of the Anio and the
solfatara of Tivoli. The temples of Pæstum, which are of extreme
antiquity, have been built with a _travertino_ formed by the sediment of
the waters which still flow in this territory. All these stones acquire
great hardness in the air, and M. de Breislak thinks that it is to the
happy union of travertino and pouzzolana in the same spot, that the
monuments of Rome owe their great solidity.

_Spongy limestone_, usually called _Agaric mineral_, stone marrow, &c.,
belongs to this kind of formation. It has a very white colour, a very
fine grain, is soft to the touch, very tender, and light enough to float
for an instant on water. It occurs in rather thin layers, in the
crevices of calcareous rocks, and is so common in Switzerland as to be
employed for whitening houses.

3. _Compact limestone_, is of a grain more or less fine, does not
polish, nor afford large blocks free from fissures, has a conchoidal, or
uneven scaly fracture. Colours very various. Its varieties are; _a_, The
_sub-lamellar_, compact, with some appearance of a foliated texture.
_b_, _Compact fine-grained limestone_, the zechstein of the Germans, to
which M. Brongniart refers the lithographic stone in his classification
of rocks (_Dictionnaire des Sciences Naturelles_,) but the English
geologists place the locality of the famous lithographic quarry of
Solenhofen much higher in the plane of secondary superposition. Its
fracture is conchoidal; colour from gray to whitish; _c_, _Compact
common limestone_. Grain of middle size; earthy aspect; uneven fracture;
perfectly opaque; colour, whitish to pale gray, yellow, or reddish. The
limestones of the Jura formation are referred to this head, as well as
most of those interspersed among the coal strata. _d_, The _coarse
compact_, or Cornbrash; texture somewhat open, earthy aspect, rough to
the touch, ragged fracture, colour yellow, gray, or dirty red. _e_,
_Compact cellular_, the Rauchekalk and Holekalk of the Germans, on
account of the numerous holes or caverns distributed through it.

4. _Oolite or roe-stone._--It consists of spherical grains of various
size, from a millet seed, to a pea, or even an egg; texture compact;
fracture even; colours, whitish, yellow, gray, reddish, brownish. The
larger balls have almost always a foreign body for their centre or
nucleus.

5. _Chalk_; texture earthy; grains fine, tender, friable; colours white,
grayish, or pale yellowish.

6. _Coarse-grained limestone_; an earthy texture, in large particles,
often loose; fracture foliated, uneven; colour pale and dirty yellow.
Coarse lias has has been referred to this head.

7. _Marly limestone_; lake and fresh-water limestone formation; texture
fine-grained, more or less dense; apt to crumble down in the air; colour
white or pale yellow; fracture rough-grained, sometimes conchoidal;
somewhat tenacious. Texture occasionally cavernous; with cylindrical
winding cavities. This true limestone must not be confounded with the
lime-marl, composed of calcareous matter and clay.

8. _Siliceous limestone_; of a compact texture; scratching steel, and
scratched by it; leaves a siliceous residuum after the action of
muriatic acid.

9. _Calp_; texture compact; fine-grained; schistose structure; hard, as
the preceding; not burning into quicklime, affording to dilute muriatic
acid a copious residuum of clay and silica; colour blackish; found in
beds in the transition district near Dublin.

10. _Lucullite_ or stinkstone; texture compact or sub-lamellar, colour
grayish; emits the smell of sulphuretted hydrogen by friction or a blow.
It occurs at Assynt, in Sutherlandshire; in Derbyshire; counties of
Kilkenny, Cork, and Galway.

11. _Bituminous limestone_; black or blackish colour; diffusing by the
action of fire a bituminous odour, and becoming white.

Of all common limestones the purity may most readily be determined by
the quantity of carbonic acid which is evolved during their solution in
dilute nitric or muriatic acid. Perfect carbonate of lime loses in this
way 46 _per cent._; and if any particular limestone loses only 23 _per
cent._, we may infer that it contains only one half its weight of
calcareous carbonate. This method is equally applicable to _marls_,
which are mixtures in various proportions of carbonate of lime, clay,
and sand, and may all be recognized by their effervescing with acids.

The chief use of calcareous stones is for procuring quicklime by
calcination in proper furnaces; and they are all adapted to this purpose
provided they are not mixed with too large a proportion of sand and
ferruginous clay, whereby they acquire a vitrescent texture in a high
heat, and will not burn into lime. Limestone used to be calcined in a
very rude kiln, formed by enclosing a circular space of 10 or 15 feet
diameter, by rude stone walls 4 or 5 feet high, and filling the
cylindrical cavity with alternate layers of turf or coal and limestone
broken into moderate pieces. A bed of brushwood was usually placed at
the bottom, to facilitate the kindling of the kiln. Whenever the
combustion was fairly commenced, the top, piled into a conical form, was
covered in with sods, to render the calcination slow and regular. This
method being found relatively inconvenient and ineffectual, was
succeeded by a permanent kiln built of stones or brickwork, in the shape
of a truncated cone with the narrow end undermost, and closed at bottom
by an iron grate. Into this kiln, the fuel and limestone were introduced
at the top in alternate layers, beginning of course with the former; and
the charge was either allowed to burn out, when the lime was altogether
removed at a door near the bottom, or the kiln was successively fed with
fresh materials, in alternate beds, as the former supply sunk down by
the calcination, while the thoroughly burnt lime at the bottom was
successively raked out by a side door immediately above the grate. The
interior of the lime kiln has been changed of late years from the
conical to the elliptical form; and probably the best is that of an egg
placed with its narrow end undermost, and truncated both above and
below; the ground plot or bottom of the kiln being compressed so as to
give an elliptical section, with an _eye_ or draft-hole towards each end
of that ellipse. A kiln thus arched in above gives a reverberatory heat
to the upper materials, and also favours their falling freely down in
proportion as the finished lime is raked out below; advantages which
the conical form does not afford. The size of the draft-notes for
extracting the quicklime, should be proportionate to the size of the
kiln, in order to admit a sufficient current of air to ascend with the
smoke and flame, which is found to facilitate the extrication of the
carbonic acid. The kilns are called _perpetual_, because the operation
is carried on continuously as long as the building lasts; and
_draw-kilns_, from the mode of discharging them by raking out the lime
into carts placed against the draft-holes. Three bushels of calcined
limestone, or lime-shells, are produced on an average for every bushel
of coals consumed. Such kilns should be built up against the face of a
cliff, so that easy access may be gained to the mouth for charging, by
making a sloping cart road to the top of the bank.

[Illustration: 638 639 640 641]

_Figs._ 638, 639, 640, 641. represent the _lime-kiln_ of Rüdersdorf near
Berlin, upon the continuous plan, excellently constructed for
economizing fuel. It is triple, and yields a threefold product. _Fig._
640. is a view of it as seen from above; _fig._ 641., the elevation and
general appearance of one side; _fig._ 638, a vertical section, and
_fig._ 639. the ground plan in the line A B C D of _fig._ 638. The inner
shaft _fig._ 638. has the form of two truncated cones, with their larger
circular ends applied to each other; it has the greatest width at the
level of the fire-door _b_, where it is 8 feet in diameter; it is
narrower below at the discharge door, and at the top orifice, where it
is about 6 feet in diameter. The interior wall _d_, of the upper shaft
is built with hewn stones, to the height of 38 feet, and below that for
25 feet, with fire-bricks _d´ d´_, laid stepwise. This inner wall is
surrounded with a mantle _e_, of limestones, but between the two there
is a small vacant space of a few inches filled with ashes, in order to
allow of the expansion of the interior with heat taking place without
shattering the mass of the building.

The fire-grate _b_, consists of fire-tiles, which at the middle, where
the single pieces press together, lie upon an arched support _f_. The
fire-door is also arched, and is secured by fire-tiles. _g_ is the iron
door in front of that orifice. The tiles which form the grate have 3 or
4 slits of an inch wide for admitting the air, which enters through the
canal _h_. The under part of the shaft from the fire to the hearth, is 7
feet, and the outer enclosing wall is constructed of limestone, the
lining being of fire-bricks. Here are the ash-pit _i_, the discharge
outlet _a_, and the canal _k_, in front of the outlet. Each ash-pit is
shut with an iron door, which is opened only when the space _i_ becomes
filled with ashes. These indeed are allowed to remain till they get
cool enough to be removed without inconvenience.

The discharge outlets are also furnished with iron doors, which are
opened only for taking out the lime, and are carefully luted with loam
during the burning. The outer walls _l m n_ of the kiln, are not
essentially necessary, but convenient, because they afford room for the
lime to lie in the lower floor, and the fuel in the second. The several
stories are formed of groined arches _o_, and platforms _p_, covered
over with limestone slabs. In the third and fourth stories the workmen
lodge at night. See _fig._ 641. Some enter their apartments by the upper
door _q_; others by the lower door _s_. _r_ is one of the chimneys for
the several fire-places of the workmen. _t u v_ are stairs.

As the limestone is introduced at top, the mouth of the kiln is
surrounded with a strong iron balustrade to prevent the danger of the
people tumbling in. The platform is laid with rails _w_, for the waggons
of limestone, drawn by horses, to run upon. _x_ is another rail-way,
leading to another kiln. Such kilns are named after the number of their
fire-doors, single, twofold, threefold, fourfold, &c.; from three to
five being the most usual. The outer form of the kiln also is determined
by the number of the furnaces; being a truncated pyramid of equal sides;
and in the middle of each alternate side there is a fire-place, and a
discharge outlet. A cubic foot of limestone requires for burning, one
and five-twelfths of a cubic foot of wood, and one and a half of turf.

When the kiln is to be set in action, it is filled with rough
limestones, to the height C D, or to the level of the firing; a wood
fire is kindled in _a_, and kept up till the lime is calcined. Upon this
mass of quicklime, a fresh quantity of limestones is introduced, not
thrown in at the mouth, but let down in buckets, till the kiln be quite
full; while over the top a cone of limestones is piled up, about 4 feet
high. A turf-fire is now kindled in the furnaces _b_. Whenever the upper
stones are well calcined, the lime under the fire-level is taken out,
the superior column falls in, a new cone is piled up, and the process
goes on thus without interruption, and without the necessity of once
putting a fire into _a_; for in the space C B, the lime must be always
well calcined. The discharge of lime takes place every 12 hours, and it
amounts at each time in a threefold kiln, to from 20 to 24 Prussian
_tonnes_ of 6 imperial bushels each; or to 130 bushels imperial upon the
average. It is found by experience, that fresh-broken limestone which
contains a little moisture, calcines more readily than what has been
dried by exposure for some time to the air; in consequence of the vapour
of water promoting the escape of the carbonic acid gas; a fact well
exemplified in distilling essential oils, as oil of turpentine and
naphtha, which come over with the steam of water, at upwards of 100
degrees F. below their natural term of ebullition. Six bushels of
Rüdersdorf quicklime weigh from 280 to 306 pounds.

When coals are used for fuel in a well-constructed perpetual, or draw
kiln, about 1 measure of them should suffice for 4 or 5 of limestone.

The most extensive employment of quicklime is in agriculture, on which
subject instructive details are given in Loudon’s Encyclopædias of
Agriculture and Gardening.

Quicklime is employed in a multitude of preparations subservient to the
arts; for clarifying the juice of the sugar-cane and the beet-root; for
purifying coal gas; for rendering the potash and soda of commerce
caustic in the soap manufacture, and in the bleaching of linen and
cotton; for purifying animal matters before dissolving out their
gelatine; for clearing hides of their hair in tanneries; for extracting
the pure volatile alkali from muriate or sulphate of ammonia; for
rendering confined portions of air very dry; for stopping the leakage of
stone reservoirs, when mixed with clay and thrown into the water; for
making a powerful lute with white of egg or serum of blood; for
preparing a depilatory pommade with sulphuret of arsenic, &c. Lime water
is used in medicine, and quicklime is of general use in chemical
researches. Next to agriculture the most extensive application of
quicklime is to MORTAR-CEMENTS, which see.


LINEN. See FLAX, and TEXTILE FABRICS.


LINSEED (_Graine de lin_, Fr.; _Leinsame_, Germ.); contains in its dry
state, 11·265 of oil; 0·146 of wax; 2·488 of a soft resin; 0·550 of a
colouring resinous matter; 0·926 of a yellowish substance analogous to
tannin; 6·154 of gum; 15·12 of vegetable mucilage; 1·48 of starch; 2·932
of gluten; 2·782 of albumine; 10·884 of saccharine extractive; 44·382 of
envelopes, including some vegetable mucilage. It contains also free
acetic acid; some acetate, sulphate, and muriate of potash, phosphate
and sulphate of lime; phosphate of magnesia; and silica. See OILS,
UNCTUOUS.


LIQUATION (Eng. and Fr.; _Saigerung_, Germ.); is the process of sweating
out, by a regulated heat, from an alloy, an easily fusible metal from
the interstices of a metal difficult of fusion. Lead and antimony are
the metals most commonly subjected to liquation; the former for the
purpose of carrying off by a superior affinity the silver present in any
complex alloy, a subject discussed under SILVER; the latter will be
considered here, as referred to from the article ANTIMONY.

[Illustration: 642 643 644]

_Figs._ 642, 643, 644. represent the celebrated antimonial liquation
furnaces of Malbosc, in the department of Ardèche, in France. _Fig._
642. is a ground plan taken at the level of the draught holes _g g_,
_fig._ 643., and of the dotted line E F; _fig._ 643. is a vertical
section through the dotted line A B, of _fig._ 642.; and _fig._ 644. is
a vertical section through the dotted line C D of _fig._ 642. In the
three figures, the same letters denote like objects, _a b c_ are three
grates upon the same level above the floor of the works, 4-1/2 feet
long, by 10-1/2 inches broad; between which are two rectangular
galleries, _d e_, which pass transversely through the whole furnace, and
lie at a level of 12 inches above the ground. They are separated by two
walls from the three fire places. The walls have three openings, _f g
h_, alternately placed for the flames to play through. The ends of these
galleries are shut in with iron doors _i i_, containing peep holes. In
each gallery are two conical cast-iron crucibles _k k_, into which the
_eliquating_ sulphuret of antimony drops. Their height is from 12 to 14
inches, the width of the mouth is 10 inches, that of the bottom is 6,
and the thickness four-tenths of an inch. They are coated over with fire
clay, to prevent the sulphuret from acting upon them; and they stand
upon cast-iron pedestals with projecting ears, to facilitate their
removal from the gallery or platform. Both of these galleries are lined
with tiles of fire-clay _l l_, which also serve as supports to the
vertical liquation tubes _m m_, made of the same clay. The tiles are
somewhat curved towards the middle, for the purpose of receiving the
lower ends of these tubes, and have a small hole at _n_, through which
the liquid sulphuret flows down into the crucible.

The liquation tubes are conical, the internal diameter at top being 10
inches, at bottom 8; the length fully 40 inches, and the thickness
six-tenths of an inch. They have at their lower ends notches or slits
_o_, _fig._ 644., from 3 to 5 inches long, which look outwards, to make
them accessible from the front and back part of the furnaces through
small conical openings _p p_, in the walls. These are closed during the
operation with clay stoppers, and are opened only when the gangue,
rubbish, and cinders are to be raked out. The liquation tubes pass
across the arch of the furnace _q q_, the space of the arch being wider
than the tubes; they are shut in at top with fire-covers _r r_. _s s_,
the middle part of the arch, immediately under the middle grate, is
barrel-shaped, so that both arches are abutted together. The flames,
after playing round about the sides of the liquation tubes, pass off
through three openings and flues into the chimney _t_, about 13 feet
high; _u_ being the one opening, and _v_ the two others, which are
provided with register plates. In front of the furnace is a smoke flue
_w_, to carry off the sulphureous vapours exhaled during the clearing
out of the rubbish and slag; another _x_, begins over _y y_, at the top
of the tubes; a wall _z_, separates the smoke flue into halves, so that
the workmen upon the one side may not be incommoded by the fumes of the
other. This wall connects at the same time the front flue _w_ with the
chimney _t_. _a´ a´_ and _b´ b´_ are iron and wooden bearer beams and
rods for strengthening the smoke-flue, _c´ c´_ are arches upon both
sides of the furnace, which become narrower from without inwards, and
are closed with well-fitted plates _d´ d´_. They serve, in particular
circumstances, to allow the interior to be inspected, and to see if
either of the liquation furnaces be out of order.

Each tube being charged with about 500 lbs. of the antimonial ore,
previously warmed upon the roof of the furnace, in a short time the
sulphuret of a blue colour begins to flow out. Whenever the liquation
ceases, the cinders are raked out by the side openings, and the tubes
are charged afresh. The luted iron crucibles are suffered to become
three-fourths full, are then drawn out from the galleries, left to cool,
and emptied. The ingots weigh about 85 pounds. The charging is renewed
every three hours, and, when the process is in good train, 100 lbs. of
sulphuret of antimony are obtained every hour. The average duration of
the tubes is 3 weeks, though in some cases it may be 40 days. The
product from the ore is from 40 to 50 per cent. The above plan of
operation is remarkable for the small consumption of fuel, the economy
of labour, and the complete exhaustion of the ore.


LIQUEURS, LIQUORISTE; names given by the French to liquors compounded of
alcohol, water, sugar, and different aromatic substances; and to the
person who compounds them. I shall insert here a few of their most
approved recipes.

_Infusion of the peels of fruits._--The outer skin pared off with a
sharp knife, is to be dropped into a hard glazed jar, containing alcohol
of 34° B., diluted with half its bulk of water, and the whole is to be
transferred into well-corked carboys. After an infusion of six weeks,
with occasional agitation, the aromatized spirit is to be distilled off.
In this way are prepared the liquors of cedrat, lemons, oranges,
_limettes_ (a sort of sweet lemon), _poncires_ (the large citron),
bergamots, &c.

_Infusion of aromatic seeds._--These must be pounded, put into a carboy,
along with alcohol diluted as above, infused with agitation for six
weeks, and then distilled.

_Infusions of aromatic woods_ are made in the same way.

The liquorist should not bring his infusions and tinctures into the
market till six months after their distillation.

Liqueurs have different titles, according to their mode of fabrication.

Thus _waters_ are liquors apparently devoid of viscidity; _creams_ and
_oils_ possess it in a high degree.

Water of _cedrat_, is made by dissolving six pounds of sugar in seven
quarts of water; adding two quarts of spirit of _cedrat_, and one of
spirit of citron. Boil the whole for a minute, and filter hot through a
proper bag. Set it for a considerable time aside in a corked carboy,
before it be bottled.

_Oil or cream of cedrat._--Take eight quarts of river water, two of
spirit of cedrat, one of spirit of citron, and as much rich syrup as is
necessary to give the mixture an oily consistence. Stir it well and set
it aside in carboys. Should it be at all clouded, it must be filtered
till it be perfectly pellucid.

_Balm of Molucca_, is made by infusing for ten days, in a carboy capable
of holding fully four gallons, 10 pounds of spirits of 18° B., 4 pounds
of white sugar, 4 pounds of river water, 4 drachms of pounded cloves,
and 48 grains of pounded mace. The mixture is to be shaken 3 or 4 times
daily, coloured with caramel (burnt sugar), filtered at the end of ten
days, and set aside in bottles.

_Tears of the widow of Malabar_, are compounded with the preceding
quantity of spirits, sugar, and water, adding 4 drachms of ground
cinnamon, 48 grains of cloves, and a like quantity of mace, both in
powder. It may be slightly coloured with caramel.

_The delight of the Mandarins._--Take spirit, sugar, and water, as
above, adding 4 drachms of _anisum Chinæ_, (_Gingi_), as much _ambrette_
(seeds of the _hibiscus abelmoschus, Lin._) all in powder; 2 drachms of
safflower.

_The sighs of love._--Take spirits, water, and sugar, as above. Perfume
with essence (otto) of roses; give a very pale pink hue with tincture of
cochineal, filter and bottle up.

_Crème de macarons._--Add to the spirit, sugar, and water as above, half
a pound of bitter almonds, blanched and pounded; cloves, cinnamon, and
mace in powder, of each 48 grains. A violet tint is given by the
tinctures of turnsole and cochineal.

_Curaçoa._--Put into a large bottle nearly full of alcohol of
_trente-six_ (34° Baumé), the peels of six smooth Portugal oranges,
(Seville?) and let them infuse for 15 days; then put into a carboy 10
pounds of spirits of 18° B., 4 pounds of white sugar, and 4 pounds of
river water. When the sugar is dissolved, add a sufficient quantity of
the orange _zestes_ to give flavour, then spice the whole with 48 grains
of cinnamon, and as much mace, both in powder. Lastly introduce an ounce
of ground Brazil wood, and infuse during 10 days, agitating 3 or 4 times
daily. A pretty deep hue ought to be given with caramel.

_Swiss extract of wormwood_, is compounded as follows:--

  Tops of the absinthium majus 4 pounds;
    Ditto, absinthium minus 2 pounds;
    Roots of angelica,             }
    Calamus aromaticus,            } of each a few grains at pleasure;
    Seeds of _anisum Chinæ_,       }
    Leaves of the dittany of Crete,}
    Alcohol of 20° B., four gallons Imp.

Macerate these substances during eight days, then distil by a gentle
fire; draw off two gallons of spirits, and add to it 2 drachms of
essential oil of anise-seed. The two gallons left in the still serve for
preparing the _vulnerary spirituous water_.

Of colouring the _liqueurs_.

_Yellow_ is given with the yellow colouring matter of safflower
(_carthamus_,) which is readily extracted by water.

_Fawn_ is given by _caramel_, made by heating ground white sugar in an
iron spoon over a charcoal fire, till it assumes the desired tint, and
then pouring it into a little cold water.

_Red_ is given by cochineal alone, or with a little alum.

_Violet_ is given by good litmus (turnsole).

_Blue_ and _green_.--Sulphate of indigo gives the first. After
saturating it nearly with chalk, alcohol being digested upon it, becomes
blue. This tincture mixed with that of carthamus forms a good green.


LIQUID AMBER, is obtained from the _liquidambar styraciflua_, a tree
which grows in Mexico, Louisiana, and Virginia. Some specimens are thin,
like oil, and others are thickish, like turpentine. It is transparent,
amber coloured, has an agreeable and powerful smell, and an aromatic
taste, which feels pungent in the throat. Boiling alcohol dissolves it
almost entirely. It contains a good deal of benzoic acid, some of which
effloresces whenever the liquid amber hardens with keeping.


LITHARGE (Eng. and Fr.; _Glätte_, Germ.); is the fused yellow protoxide
of lead, which on cooling passes into a mass consisting of small
six-sided plates, of a reddish yellow colour, and semitransparent. It
generally contains more or less red lead, whence the variations of its
colour; and carbonic acid, especially when it has been exposed to the
air for some. time. See LEAD, and SILVER, for its mode of preparation.


LITHIA, is a simple earthy or alkaline substance, discovered not many
years ago, in the minerals called petalite and triphane. It is white,
very caustic, reddens litmus, and red cabbage, and saturates acids with
great facility. When exposed to the air it attracts humidity and
carbonic acid. It is more soluble in water than baryta; and has such a
strong affinity for it, as to be obtained only in the state of a
hydrate. It forms neutral salts with all the acids. It is most
remarkable for its power of acting upon, or corroding platinum.


LITHIUM, is the metallic basis of Lithia; the latter substance consists
of 100 of metal, and 123 of oxygen.


LITHOGRAPHY. Though this subject belongs rather to the arts of taste and
design than to productive manufactures, its chemical principles fall
within the province of this Dictionary.

The term _lithography_ is derived from λιθος, _a stone_, and γραφη,
_writing_, and designates the art of throwing off impressions upon
paper, of figures and writing previously traced upon stone. The
processes of this art are founded:--

1. Upon the adhesion to a smoothly-polished limestone, of an encaustic
fat which forms the lines or traces.

2. Upon the power acquired by the parts penetrated by this encaustic, of
attracting to themselves, and becoming covered with a printer’s ink,
having linseed oil for its basis.

3. Upon the interposition of a film of water, which prevents the
adhesion of the ink in all the parts of the surface of the stone not
impregnated with the encaustic.

4. Lastly, upon a pressure applied by the stone, such as to transfer to
paper the greater part of the ink which covers the greasy tracings of
the encaustic.

The lithographic stones of the best quality are still procured from the
quarry of Solenhofen, a village at no great distance from Munich, where
this mode of printing had its birth. They resemble in their aspect the
yellowish white lias of Bath, but their geological place is much higher
than the lias. Abundant quarries of these fine-grained limestones occur
in the county of Pappenheim, along the banks of the Danube, presenting
slabs of every required degree of thickness, parted by regular seams,
and ready for removal with very little violence. The good quality of a
lithographic stone is generally denoted by the following characters; its
hue is of a yellowish gray, and uniform throughout; it is free from
veins, fibres, and spots; a steel point makes an impression on it with
difficulty; and the splinters broken off from it by the hammer, display
a conchoidal fracture.

The Munich stones are retailed on the spot in slabs or layers of equal
thickness; they are quarried with the aid of a saw, so as to sacrifice
as little as possible of the irregular edges of the rectangular tables
or plates. One of the broad faces is then dressed, and coarsely
smoothed. The thickness of these stones is nearly proportional to their
other dimensions; and varies from an inch and two-thirds to 3 inches.

In each lithographic establishment, the stones receive their finishing,
dressing, and polishing; which are performed like the grinding and
polishing of mirror plate. The work is done by hand, by rubbing
circularly a movable slab over another cemented in a horizontal
position, with fine sifted sand and water interposed between the two.
The style of _work_ that the stone is intended to produce, determines
the kind of polish that it should get. For crayon drawing the stone
should be merely grained more or less _fine_ according to the fancy of
the draughtsman. The higher the finish of the surface, the softer are
the drawings; but the printing process becomes sooner _pasty_, and a
smaller number of impressions can be taken. _Works in ink_ require the
stone to be more softened down, and finally polished with pumice and a
little water. The stones thus prepared are packed for use with white
paper interposed between their faces.

_Lithographic crayons._--Fine lithographic prints cannot be obtained
unless the crayons possess every requisite quality. The ingredients
composing them ought to be of such a nature as to adhere strongly to the
stone, both after the drawing has undergone the preparation of the acid,
and during the press-work. They should be hard enough to admit of a fine
point, and trace delicate lines without risk of breaking. The following
composition has been successfully employed for crayons by MM. Bernard
and Delarue, at Paris:--

  Pure wax, (first quality)                4
  Dry white tallow soap                    2
  White tallow                             2
  Gum lac                                  2
  Lamp black, enough to give a dark tint   1
  Occasionally copal varnish               1

The wax is to be melted over a gentle fire, and the lac broken to bits
is then to be added by degrees, stirring all the while with a spatula;
the soap is next introduced in fine shavings; and when the mixture of
these substances is very intimately accomplished, the copal-varnish,
incorporated with the lamp black, is poured in. The heat and agitation
are continued till the paste has acquired a suitable consistence; which
may be recognised by taking out a little of it, letting it cool on a
plate, and trying its quality with a penknife. This composition, on
being cut, should afford brittle slices. The boiling may be quickened by
setting the rising vapours on fire, which increases the temperature, and
renders the exhalations less offensive. When ready, it is to be poured
into a brass mould, made of two semi-cylinders joined together by clasps
or rings, forming between them a cylindric tube of the crayon size. The
mould should be previously smeared with a greasy cloth.

M. Lasteyrie prescribes a more simple composition, said to be equally
fit for the lithographer’s use:--

  Dried white tallow soap      6 parts.
  White wax                    6   --
  Lamp black                   1   --

The soap and tallow are to be put into a small goblet and covered up.
When the whole is thoroughly fused by heat, and no clots remain, the
black is gradually sprinkled in with careful stirring.

Lithographic ink is prepared nearly on the same principles:--

  Wax                    16 parts.
  Tallow                  6   --
  Hard tallow soap        6   --
  Shell-lac              12   --
  Mastic in tears         8   --
  Venice turpentine       1   --
  Lamp black              4   --

The mastic and lac, previously ground together, are to be heated with
care in the turpentine; the wax and tallow are to be added after they
are taken off the fire, and when their solution is effected, the soap
shavings are to be thrown in. Lastly, the lamp black is to be well
intermixed. Whenever the union is accomplished by heat, the operation is
finished; the liquor is left to cool a little, then poured out on
tables, and, when cold, cut into square rods.

Lithographic ink of good quality ought to be susceptible of forming an
emulsion so attenuated, that it may appear to be dissolved when rubbed
upon a hard body in distilled or river water. It should be flowing in
the pen, not spreading on the stone; capable of forming delicate traces,
and very black to show its delineations. The most essential quality of
the ink is to sink well into the stone, so as to re-produce the most
delicate outlines of the drawing, and to afford a great many
impressions. It must therefore be able to resist the acid with which the
stone is moistened in the preparation, without letting any of its greasy
matter escape.

M. de Lasteyrie states that after having tried a great many
combinations, he gives the preference to the following:--

  Tallow soap, dried           30 parts.
  Mastic, in tears             30   --
  White soda of commerce       30   --
  Shell-lac                   150   --
  Lamp black                   12   --

The soap is first put into the goblet and melted over the fire, to which
the lac being added fuses immediately; the soda is then introduced, and
next the mastic, stirring all the while with a spatula. A brisk fire is
applied till all these materials be melted completely, when the whole is
poured out into the mould.

The inks now prescribed may be employed equally with the pen and the
hair pencil, for writings, black-lead drawings, _aqua tinta_, mixed
drawings, those which represent engravings on wood (wood cuts), &c. When
the ink is to be used it is to be rubbed down with water, in the manner
of China ink, till the shade be of the requisite depth. The temperature
of the place ought to be from 84° to 90° Fahr., or the saucer in which
the ink-stick is rubbed should be set in a heated plate. No more ink
should be dissolved than is to be used at the time, for it rarely keeps
in the liquid state for 24 hours; and it should be covered or corked up.

_Autographic paper._--Autography, or the operation by which a writing or
a drawing is transferred from paper to stone, presents not merely a
means of abridging labour, but also that of _re_verting the writings or
drawings into the direction in which they were traced, whilst, if
executed directly upon the stone, the impression given by it is
_in_verted. Hence, a writing upon stone must be inverted from right to
left to obtain direct impressions. But the art of writing thus is
tedious and difficult to acquire, while, by means of the autographic
paper and the transfer, proofs are obtained in the same direction with
the writing and drawing.

_Autographic ink._--It must be fatter and softer than that applied
directly to the stone, so that though dry upon the paper, it may still
preserve sufficient viscidity to stick to the stone by mere pressure.

To compose this ink, we take--

  White soap                              100 parts.
  White wax of the best quality           100   --
  Mutton suet                              30   --
  Shell-lac                                50   --
  Mastic                                   50   --
  Lamp black                         30 or 35   --

These materials are to be melted as above described for the lithographic
ink.

_Lithographic ink and paper._--The following recipes have been much
commended:

  Virgin or white wax      8 parts
  White soap               2   --
  Shell-lac                2   --
  Lamp black               3 table-spoonsful.

_Preparation._--The wax and soap are to be melted together, and before
they become so hot as to take fire, the lamp black is to be well stirred
in with a spatula, and then the mixture is to be allowed to burn for 30
seconds; the flame being extinguished, the lac is to be added by
degrees, carefully stirring all the time; the vessel is to be put upon
the fire once more in order to complete the combination, and till the
materials are either kindled or nearly so. After the flame is
extinguished, the ink must be suffered to cool a little, and then put
into the moulds.

With the ink crayons thus made, lines may be drawn as fine as with the
point of the graver, and as full as can be desired, without risk of its
spreading in the carriage. Its traces will remain unchanged on paper for
years before being transferred.

Some may think it strange that there is no suet in the above
composition, but it has been found that ink containing it is only good
when used soon after it is made, and when immediately transferred to
the stone, while traces drawn on paper with the suet ink become
defective after 4 or 5 days.

  _Lithographic paper._--Lay on the paper,
       3 successive coats of sheep-feet jelly,
       1 layer of white starch,
       1 layer of gamboge.

The first layer is applied with a sponge dipped in the solution of the
hot jelly, very equally over the whole surface, but thin; and if the
leaf be stretched upon a cord, the gelatine will be more uniform. The
next two coats are to be laid on, until each is dry. The layer of starch
is then to be applied with a sponge, and it will also be very thin and
equal. The coat of gamboge is lastly to be applied in the same way. When
the paper is dry, it must be smoothed by passing it through the
lithographic press; and the more polished it is, the better does it take
on the ink in fine lines.

_Transfer._--When the paper is moistened, the transfer of the ink from
the gamboge is perfect and infallible. The starch separates from the
gelatine, and if, after taking the paper off the stone, we place it on a
white slab of stone, and pour hot water over it, it will resume its
primitive state.

The coat of gamboge ought to be laid on the same day it is dissolved, as
by keeping, it becomes of an oily nature; in this state it does not
obstruct the transfer, but it gives a gloss to the paper which renders
the drawing or tracing more difficult, especially to persons little
habituated to lithography.

The starch paste can be employed only when cold, the day after it is
made, and after having the skin removed from its surface.

A leaf of such lithographic paper may be made in two minutes.

In transferring a writing, an ink drawing, or a lithographic crayon,
even the impression of a copper-plate, to the stone, it is necessary, 1.
that the impressions be made upon a thin and slender body like common
paper; 2. that they may be detached and fixed totally on the stone by
means of pressure; but as the ink of a drawing sinks to a certain depth
in paper, and adheres pretty strongly, it would be difficult to detach
all its parts, were there not previously put between the paper and the
traces, a body capable of being separated from the paper, and of losing
its adhesion to it by means of the water with which it is damped. In
order to produce this effect, the paper gets a certain preparation,
which consists in coating it over with a kind of paste ready to receive
every delineation without suffering it to penetrate into the paper.
There are different modes of communicating this property to paper.
Besides the above, the following may be tried. Take an unsized paper,
rather strong, and cover it with a varnish composed of:--

  Starch          120 parts
  Gum arabic       40   --
  Alum             20   --

A paste of moderate consistence must be made with the starch and some
water, with the aid of heat, into which the gum and alum are to be
thrown, each previously dissolved in separate vessels. When the whole is
well mixed, it is to be applied, still hot, on the leaves of paper, with
a flat smooth brush. A tint of yellow colour may be given to the
varnish, with a decoction of the berries of Avignon, commonly called
French berries by our dyers. The paper is to be dried, and smoothed by
passing under the scraper of the lithographic press.

Steel pens are employed for writing and drawing with ink on the
lithographic stones.


LITMUS (_Tournesol_, Fr.; _Lackmus_, Germ.); is prepared in Holland from
the species of lichen called _Lecanora tartarea_, _Roccella tartarea_,
by a process which has been kept secret, but which is undoubtedly
analogous to that for making archil and cudbear. The ground lichens are
first treated with urine containing a little potash, and allowed to
ferment, whereby they produce a purple-red; the coloured liquor, treated
with quicklime and some more urine, is set again to ferment during two
or three weeks, then it is mixed with chalk or gypsum into a paste,
which is formed into small cubical pieces, and dried in the shade.
Litmus has a violet-blue colour, is easy to pulverize, is partially
soluble in water and dilute alcohol, leaving a residuum consisting of
carbonate of lime, of clay, silica, gypsum, and oxide of iron combined
with the dye. The colour of litmus is not altered by alkalis, but is
reddened by acids; and is therefore used in chemistry as a delicate test
of acidity, either in the state of solution or of unsized paper stained
with it. It is employed to dye marble blue.


LIXIVIATION (_Lessivage_, Fr.; _Auslagen_, Germ.); signifies the
abstraction by water of the soluble alkaline or saline matters present
in any earthy admixture; as from that of quicklime and potashes to make
potash lye, from that of effloresced alum schist to make aluminous
liquors, &c.


LOADSTONE, MAGNETIC IRON-STONE (_Fer oxydulé_, Fr.; _Magneteisenstein_,
Germ.); an iron ore consisting of the protoxide and peroxide of iron in
a state of combination.


LOAM (_Terre-limoneuse_, Fr.; _Lehm_, Germ.); a native clay mixed with
quartz sand and iron ochre, and occasionally with some carbonate of
lime.


LODE, is the name given by the Cornish miners to a vein, whether it be
filled with metallic or earthy matter.


LOGWOOD (_Bois de Campèche_, _Bois bleu_, Fr.; _Blauholz_, Germ.); is
the wood of the _Hæmatoxylon Campechianum_, a native tree of central
America, grown in Jamaica since 1715. It was first introduced into
England in the reign of Elizabeth, but as it afforded to the unskilful
dyers of her time a fugitive colour, it was not only prohibited from
being used, under severe penalties, but was ordered to be burned
wherever found, by a law passed in the 23d year of her reign. The same
prejudice existed, and the same law was enacted against indigo. At
length, after a century of absurd prohibition, these two most valuable
tinctorial matters, by which all our hats, and the greater part of our
woollen cloths, are dyed, were allowed to be used.

Old wood, with black bark and with little of the white alburnum, is
preferred. Logwood is denser than water, very hard, of a fine compact
grain, and almost indestructible by the atmospheric elements; it has a
sweet and astringent taste, and a peculiar not inoffensive smell.

For its chemical composition, see HEMATIN.

When chipped logwood is for some time exposed to the air, it loses a
portion of its dyeing power. Its decoction absorbs the oxygen of the
atmosphere, and then acquires the property of precipitating with
gelatine, which it had not before. The dry extract of logwood, made from
an old decoction, affords only a fugitive colour.

For its applications in dyeing, see BLACK DYE; BROWN DYE; CALICO
PRINTING; DYEING; HAT DYEING, &c.

The imports of logwood for home use, were, in 1836, 12,880 tons, 13
cwts.; in 1837, 14,677 tons, 13 cwts. And the amount of duty received
was, in 1836, 2,480_l._; in 1837, 2,552_l._


LOOM (_Metier a tisser_, Fr.; _Weberstuhl_, Germ.); is the ancient and
well-known machine for weaving cloth by the decussation of a series of
parallel threads, which run lengthwise, called the warp or chain, with
other threads thrown transversely with the shuttle, called the woof or
weft. See JACQUARD LOOM and WEAVING.


LUBRICATION. The following simple and efficacious plan of lubricating
the joints and bearings of machinery by capillary attraction, has been
kindly communicated to me, by its ingenious inventor, Edward Woolsey,
Esq.:--

[Illustration: 645, 646, 647]

_Fig._ 645. represents a tin cup, which has a small tin tube A, which
passes through the bottom, as shown by the dotted lines. It may have a
tin cover to keep out the dust.

_Fig._ 646. is a plan of the same.

_Fig._ 647. is a section of the same. Oil is poured into the cup, and
one end of a worsted or cotton thread is dipped into the oil, and the
other end passed through the tube. The capillary attraction causes the
oil to ascend and pass over the orifice of the tube, whence it gradually
descends, and drops slower or quicker, according to the length of the
thread, or its thickness, until every particle of oil is drawn over by
this capillary syphon. The tube is intended to be put into the bearings
of shafts, &c., and is made of any size that may be wished. If oil, or
other liquids, is desired to be dropped upon a grindstone or other
surface, this cup can have a handle to it, or be hung from the ceiling.

[Illustration: 648]

_Fig._ 648. It is frequently required to stop the capillary action when
the machinery is not going; and this has been effected by means of a
tightening screw, which passes through a screw boss in the cover of the
cup, and presses against the internal orifice of the tube, preventing
the oil from passing.

[Illustration: 649 650 651 652]

_Fig._ 649. As I find when these screw cups (_fig._ 648.) are used upon
beams of engines and moving bearings, that the screw is apt to be
tightened by the motion; and also, as I think the action of the screw is
uncertain, from the workman neglecting to screw it down sufficiently, it
answers best to take out the capillary thread when the lubrication is
not required; and to effect this easily, I have a tin top to the cup,
with a round pipe soldered to it: this pipe has a slit in it, like a
pencil case, and allows a bolt B to slide easily in it. In _fig._ 650.
the bolt is down; in _fig._ 651., the bolt, which is a piece of brass
wire, is drawn up, and there is no capillary action between the thread
and the oil. In _fig._ 651. it will be observed, that the bolt is kept
in its place by its head C, resting in a lateral slit in the pipe, and
it cannot be drawn out on account of the pin E. One end of the thread is
fastened to the eye-hole at the bottom of the bolt, and the other end is
tied to a small wire which crosses the lower orifice of the tube at D
and which is shown in plan _fig._ 652.

By this simple contrivance the capillary action can be stopped or
renewed in a second, without removing the top of the lubricator.

The saving by this plan, instead of pouring oil into the bearings, is 2
gallons out of 3, while the bearings are better oiled.

  “I send you the drawings of the lubricators, with a detailed
  explanation. I have omitted to state, that the saving in labour is
  considerable where there are many joints to keep oiled three or four
  times a day; and that the workman does not, with this apparatus, run
  the risk of being caught by the machinery. Perhaps your friends may be
  at a loss how to tie on the cotton or worsted thread. I pass a long
  thread through the eye-hole E of the bolt, and then draw the two ends
  through the tube by a fine wire with a hook to it, one end on one side
  of the cross wire D, and the other end on the other side. I then put
  the cover on, and the bolt in the position shown in _fig._ 651.; when
  by drawing the two ends of the thread, and tying them across the wire
  D, you have the exact length required. When you wish to see the
  quantity of oil remaining in the lubricator, the bolt must be dropped
  as in _fig._ 650., and you can then lift the cover a little way off,
  without breaking the thread, and replenish with oil. The cost of
  _fig._ 650. in tin plate is 9_d._ The figures in the wood cuts are one
  third of the full size.

  “Believe me to be yours sincerely,

  “E. J. WOOLSEY.”


LUPININE, is a substance of a gummy appearance, so named by M. Cussola,
because it was obtained from Lupines.


LUPULINE, from _Humulus Lupulus_; is the peculiar bitter aromatic
principle of the hop. See BEER.


LUTE (from _lutum_, clay; _Lut_, Fr.; _Kitte_, _Beschläge_, Germ.); is a
pasty or loamy matter employed to close the joints of chemical
apparatus, or to coat their surfaces, and protect them from the direct
action of flame. Lutes differ according to the nature of the vapours
which they are destined to confine, and the degree of heat which they
are to be exposed to.

1. _Lute of linseed meal_, made into a soft plastic dough with water,
and immediately applied pretty thick to junctions of glass, or
stone-ware, makes them perfectly tight, hardens speedily, resists acid
and ammoniacal vapours, as also a moderate degree of heat. It becomes
stronger when the meal is kneaded with milk, lime-water, or solution of
glue.

2. Lute of thick gum-water, kneaded with clay, and iron filings, serves
well for permanent junctions, as it becomes extremely solid.

3. By softening in water a piece of thick brown paper, kneading it first
with rye-flour paste, and then with some potter’s clay, till it acquire
the proper consistence, a lute is formed which does not readily crack or
scale off.

4. Lute, consisting of a strong solution of glue kneaded into a dough
with new slaked lime, is a powerful cement, and with the addition of
white of egg, forms the _lut d’ane_;--a composition adapted to mend
broken vessels of porcelain and stone-ware.

5. Skim-milk cheese, boiled for some time in water, and then triturated
into paste with fresh-slaked lime, forms also a good lute.

6. Calcined gypsum, diffused through milk, solution of glue or starch,
is a valuable lute, in many cases.

7. A lute made with linseed, melted caoutchouc, and pipe-clay,
incorporated into a smooth dough, may be kept long soft when covered in
a cellar, and serves admirably to confine acid vapours. As it does not
harden, it may therefore be applied and taken off as often as we please.

8. Caoutchouc itself, after being melted in a spoon, may be
advantageously used for securing joints against chlorine and acid
vapours, in emergencies when nothing else would be effectual. It bears
the heat at which sulphuric acid boils.

9. The best lute for joining crucibles inverted into each other, is a
dough made with a mixture of fresh fire-clay, and ground fire-bricks,
worked with water. That cement if made with solution of borax answers
still better, upon some occasions, as it becomes a compact vitreous mass
in the fire. See CEMENTS.


LUTEOLINE, is a yellow colouring matter discovered by Chevreul in weld.
When sublimed, it crystallizes in needles.


LYCOPODIUM CLAVATUM. The seeds of the lycopodium ripen in September.
They are employed, on account of their great combustibility, in
theatres, to imitate the sudden flash of lightning, by throwing a
quantity of them from a powder puff, or bellows, across the flame of a
candle.


LYDIAN STONE, is flint-slate.




M.


MACARONI, is a dough of fine wheat flour, made into a tubular or pipe
form, of the thickness of goose-quills, which was first prepared in
Italy, and introduced into commerce under the name of Italian or Genoese
paste. The wheat for this purpose must be ground into a coarse flour,
called _gruau_ or _semoule_, by the French, by means of a pair of light
mill-stones, placed at a somewhat greater distance than usual. This
_semoule_ is the substance employed for making the dough. For the mode
of manufacturing it into pipes, see VERMICELLI.


MACE, is a somewhat thick, tough, unctuous membrane, reticulated or
chapt, of a yellowish-brown or orange colour. It forms the envelop of
the shell of the fruit of the _myristica moschata_, which contains the
nutmeg. It is dried in the sun, after being dipped in brine; sometimes
it is sprinkled over with a little brine, before packing, to prevent the
risk of moulding. Mace has a more agreeable flavour than nutmeg; with a
warm and pungent taste. It contains two kinds of oil; the one of which
is unctuous, bland, and of the consistence of butter; the other is
volatile, aromatic, and thinner. The membrane is used as a condiment in
cookery, and the aromatic oil in medicine.


MACERATION (Eng. and Fr.; _Einweichen_, Germ.), is a preparatory steep
to which certain vegetable and animal substances are submitted, with the
view of distending their fibres or pores, and causing them to be
penetrated by such menstrua as are best adapted to extract their soluble
parts. Water, alone, or mixed with acids, alkalis, or salts; alcohol and
ether, are the liquids usually employed for that purpose.


MACLE, is the name of certain diagonal black spots in minerals, like the
ace of diamonds in cards, supposed to proceed from some disturbance of
the particles in the act of crystallization.


MADDER (_Garance_, Fr.; _Färberröthe_, Germ.), a substance very
extensively used in dyeing, is the root of the _Rubia tinctorum_, a
plant, of which two species are distinguished by Linnæus.

The best roots are those which have the size of a writing quill, or, at
most, of the little finger. They are semitransparent, and reddish; have
a strong odour, and a smooth bark. They should be of two or three years’
growth.

The madder, taken from the ground and picked, must be dried in order to
be ground and preserved. In warm climates it is dried in the open air;
but, elsewhere, stoves must be employed.

The stringy filaments and epidermis are to be removed, called _mulle_;
as also the pith, so as to leave nothing but the ligneous fibres.

The preparation of madders is carried on in the department of the Rhone,
in the following manner.

The roots are dried in a stove, heated by means of a furnace, from which
the air is allowed to issue only at intervals, at the moment when it is
judged to be saturated with moisture. The furnace-flue occupies a great
portion of the floor; above are three close gratings, on which the roots
are distributed in layers of about two decimetres (nearly 8 inches). At
the end of 24 hours, those which are on the first grated floor directly
above the stove are dry, when they are taken away and replaced by those
of the superior floors. This operation is repeated whenever the roots
over the stove are dry. The dry roots are thrashed with a flail, passed
through fanners similar to those employed for corn, and then shaken upon
a very coarse sieve. What passes through is farther winnowed and sifted
through a finer sieve than the first. These operations are repeated five
times, proceeding successively to sieves still finer and finer, and
setting aside every time what remains on the sieve. What passes through
the fifth sieve is rejected as sand and dust. After these operations,
the whole fibrous matters remaining on the sieve are cleaned with common
fanners, and women separate all the foreign matters which had not been
removed before. For dividing the roots, afterwards, into different
qualities, a brass sieve is made use of, whose meshes are from six to
three millimetres in diameter (from 1/4th to 1/8th inch E.) What passes
through the finest is rejected; and what passes through the coarsest is
regarded as of the best quality. These roots thus separated, are carried
into a stove, of a construction somewhat different from the first. They
are spread out in layers of about a decimetre in thickness (nearly 4
inches E.), on large lattice-work frames, and the drying is known to be
complete, when on taking up a handful and squeezing it, the roots break
easily. On quitting the stove, the madder is carried, still hot, into a
machine, where it is minced small, and a sieve separates the portion of
the bark reduced to powder. This operation is repeated three or four
times, and then the boulter is had recourse to. What passes through the
sieve, or the brass meshes of the boulter, is regarded as common madder;
and what issues at the extremity of the boulter is called the flour.
Lastly, the madder which passes through the boulter is ground in a mill
with vertical stones, and then passed through sieves of different sizes.
What remains above is always better than what goes through.

The madder of Alsace is reduced to a very fine powder, and its colouring
matter is extracted by a much longer ebullition than is necessary for
the lizari of the Levant. The prepared madders ought to be carefully
preserved from humidity, because they easily imbibe moisture, in which
case fermentation spoils their colour.

D’Ambourney and Beckman have asserted, that it is more advantageous to
employ the fresh root of madder than what has been submitted to
desiccation, especially by means of stoves. But in its states of
freshness, its volume becomes troublesome in the dyeing bath, and
uniform observation seems to prove that it ameliorates by age. Besides,
it must be rendered susceptible of keeping and carrying easily.

It appears that madder may be considered as composed of two colouring
substances, one of which is dun (tawny), and the other is red. Both of
these substances may combine with the stuff. It is of consequence,
however, to fix only the red part. The dun portion appears to be more
soluble, but its fixity on stuffs may possibly be increased by the
affinity which it has for the red portion.

The different additions made to madder, and the multiplied processes to
which it is sometimes exposed, have probably this separation for their
chief object.

The red portion of madder is soluble, but in small quantity, in water.
Hence but a limited concentration can be given to its solution. If the
portion of this substance be too much increased, so far from obtaining a
greater effect, we merely augment the proportion of the dun part, which
is the more soluble of the two.

In consequence of the Société Industrielle of Mulhausen having offered
in the year 1826 large premiums to the authors of the best analytical
investigation of madder, eight memoirs were transmitted to it in the
year 1827. They were examined with the greatest care by a committee
consisting of able scientific and practical men. None of the competitors
however fulfilled the conditions of the programme issued by the
society; but four of them received a tribute of esteem and gratitude
from it; MM. Robiquet and Colin at Paris, Kuhlmann at Lille, and
Houton-Libillardière. Fresh premiums were offered for next year, to the
amount of 2000 francs.

Every real discovery made concerning this precious root, would be of
vast consequence to dyers and calico-printers. Both M. Kuhlmann, and
Robiquet and Colin, conceived that they had discovered a new principle
in madder, to which they gave the name _alizarine_. The latter two
chemists treated the powdered madder with sulphuric acid, taking care to
let it heat as little as possible. By this action the whole is
carbonized, except perhaps the red matter. The charcoal thus obtained is
pulverized, mixed with water, thrown upon a filter, and well washed in
the cold. It is next dried, ground, and diffused through fifty parts of
water, containing six parts of alum. This mixture is then boiled for one
quarter of an hour, and thrown upon a filter cloth while boiling hot.
The residuum is once more treated with a little warm alum water. The two
liquors are to be mixed, and one part of sulphuric acid poured into
them; when they are allowed to cool with occasional agitation. Flocks
now make their appearance; the clear liquid is decanted, and the grounds
are thrown upon a filter. The precipitate is to be washed, first with
acidulated water, then with pure water, and dried, when the colouring
matter is obtained in a red or purple state. This purple substance, when
heated dry, gives out alizarine, and an empyreumatic oil, having an
odour of animal matter; while a charcoally matter remains.

M. Dan. Kœchlin, the justly celebrated calico-printer of Mulhausen, has
no faith in alizarine as the dyeing principle of madder; and thinks
moreover that, were it of value, it could not be extracted on the great
scale, on account of the destructive heat which would result from the
acid acting upon a considerable body of the ground madder. Their
alizarine is not a uniform substance, as it ought to be, if a proximate
principle; for samples of it obtained in different repetitions of the
process have produced very variable effects in dyeing. The madders of
Avignon, though richer in colour than those of Alsace, afford however
little or no alizarine. In fact, _purpurine_, the crude substance from
which they profess to extract alizarine, is a richer dye than this
_pure_ substance itself.

Madder contains so beautiful and so fast a colour, that it has become of
almost universal employment in dyeing; but that colour is accompanied
with so many other substances which mask and degrade it, that it can be
brought out and fixed only after a series of operations more or less
difficult and precarious. This dye is besides so little soluble, that
much of it is thrown away in the dye-house; the portion supposed to be
exhausted being often as rich as other fresh madder; hence it would be a
most valuable improvement in this elegant art to insulate this
tinctorial body, and make it a new product of manufacture.

Before the time of Haussmann, an apothecary at Colmar, the madder bath
was subject to many risks, which that skilful chemist taught dyers how
to guard against, by introducing a certain quantity of chalk into the
bath. A change of residence led Haussmann to this fortunate result.
After having made very fine reds at Rouen, he encountered the greatest
obstacles in dyeing the same reds at Logelbach near Colmar, where he
went to live. Numerous trials, undertaken with the view of obtaining the
same success in his new establishment, proved that the cause of his
favourable results at Rouen existed in the water, which contained
carbonate of lime in solution, whilst the water of Logelbach was nearly
pure. He then tried a factitious calcareous water, by adding chalk to
his dye bath. Having obtained the most satisfactory results, he was not
long of producing here as beautiful and as solid reds as he had done at
Rouen. This practice became soon general among the calico-printers of
Alsace, though in many dye-works the chalk is now replaced by lime,
potash, or soda. But when the madder of Avignon is used, all these
antacid correctives become unnecessary, because it contains a sufficient
quantity of carbonate of lime; an important fact first analytically
demonstrated by that accurate chemist M. Henri Schlumberger of
Mulhausen. Avignon madder indicates the presence of carbonate of lime in
it, by effervescing with dilute acids, which Alsace madder does not.

M. Kuhlmann found a free acid resembling the malic, in his analysis of
madders. But his experiments were confined to those of Alsace. The
madders of Avignon are on the contrary alkaline, as may be inferred from
the violet tint of the froth of their infusions; whereas that of the
Alsace madders is yellowish, and it strongly reddens litmus paper. This
important difference between the plants of these two districts, depends
entirely upon the soil; for madders grown in a calcareous shelly soil in
Alsace, have been found to be possessed of the properties of the Avignon
madder.

The useful action of the carbonate and the phosphate of lime in the
madder of Avignon, explains why madders treated with acids which remove
their calcareous salts, without taking away their colouring matter, lose
the property of forming fast dyes. Many manufacturers are in the habit
of mixing together, and with advantage, different sorts of madder. That
of Avignon contains so much calcareous matter that, when mixed with the
madder of Alsace, it can compensate for its deficiency. Some of the
latter is so deficient as to afford colours nearly as fugitive as those
of Brazil wood and quercitron. The Alsace madders by the addition of
chalk to their baths, become as fit for dyeing Turkey reds as those of
Avignon. When the water is very pure, one part of chalk ought to be used
to five of Alsace madder, but when the waters are calcareous, the chalk
should be omitted. Lime, the neutral phosphate of lime, the carbonate of
magnesia, oxide and carbonate of zinc, and several other substances have
the property of causing madder to form a fast dye, in like manner as the
carbonate of lime.

The temperature of from 50° to 60° R. (145° to 167° F.), is the best
adapted to the solution of the colouring matter, and to its combination
with the mordants; and thus a boiling heat may be replaced
advantageously by the long continuance of a lower temperature. A large
excess of the dye-stuff in the bath is unfavourable in two points of
view; it causes a waste of colouring matter, and renders the tints dull.
It is injurious to allow the bath to cool, and to heat it again.

In a memoir published by the Society of Mulhausen, in September, 1835,
some interesting experiments upon the growth of madders in factitious
soils are related by MM. Kœchlin, Persoz, and Schlumberger. A patch of
ground was prepared containing from 50 to 80 per cent. of chalky matter,
and nearly one fifth of its bulk of good horse-dung. Slips of Alsace and
Avignon madders were planted in March, 1834, and a part of the roots
were reaped in November following. These roots, though of only six
months growth, produced tolerably fast dyes, nor was any difference
observable between the Alsace and the Avignon species; whilst similar
slips or cuttings, planted in a natural non-calcareous soil, alongside
of the others, yielded roots which gave fugitive dyes. Others were
planted in the soil of Palud, transported from Avignon, which contained
more than 90 per cent. of carbonate of lime, and they produced roots
that gave still faster dyes than the preceding. Three years are
requisite to give the full calcareous impregnation to the indigenous
madders of Avignon.

As to the function of the chalk, valuable observations, made long ago by
M. Daniel Kœchlin, have convinced him, that the combination of two
different bases with a colouring matter, gave much more solidity to the
dye, in consequence, undoubtedly, of a greater insolubility in the
compound. Experiments recently made by him and his colleagues above
named, prove that in all cases of madder-dyeing under the influence of
chalk, a certain quantity of lime becomes added to the aluminous
mordant. In the subsequent clearing with a soap bath, some of the
alumine is removed, and there remains upon the fibre of the cloth a
combination of these two earths in atomic proportions. Thus the chalk is
not for the purpose of saturating the acid, as had been supposed, but of
forming a definite compound with alumina, and probably also with the
fatty bodies, and the colouring matter itself.

The red mordants are prepared commonly in Alsace, as follows:--The
crushed alum and acetate of lead being weighed, the former is put into a
deep tub, and dissolved by adding a proper quantity of hot water, when
about one tenth of its weight of soda crystals is introduced to saturate
the excess of acid in the alum. The acetate of lead is now mixed in; and
as this salt dissolves very quickly, the reaction takes place almost
instantly. Care must be taken to stir for an hour. The vessel should not
be covered, lest its contents should cool too slowly.

The different mordants most generally employed for madder, are detailed
under _Colours_, in CALICO-PRINTING and MORDANT.

Much mordant should not be prepared at once, for sooner or later it will
deposit some sub-acetate of alumina. This decomposition takes place even
in corked phials in the cold; and the precipitate does not readily
dissolve again in acetic acid. All practical men know that certain
aluminous mordants are decomposed by heating them, and restored on
cooling, as Gay Lussac has pointed out. He observed, that by adding to
pure acetate of alumina, some alum or sulphate of potash, the mixture
acquires the property of forming a precipitate with a heat approaching
the boiling point, and of redissolving on cooling. The precipitate is
alumina nearly pure, according to M. Gay Lussac; but, by M. Kœchlin’s
more recent researches, it is shown to be sub-sulphate of alumina,
containing eight times as much base as the neutral sulphate.

_Madder dye._--On account of the feeble solubility of its colouring
matter in water, we cannot dye with its decoction; but we must boil the
dye-stuff along with the goods to be dyed; thereby the water dissolves
fresh portions of the dye, and imparts it in succession to the textile
fibres. In dyeing with madder, we must endeavour to fix as little of the
dun matter as possible upon the cloth.

_Dyeing on wool._--Alumed wool takes, in the madder bath, a red colour,
which is not so bright as cochineal red, but it is faster; and as it is
far cheaper, it is much used in England to dye soldiers cloth. A mordant
of alum and tartar is employed; the bath of madder, at the rate of from
8 to 16 ounces for the pound of cloth, is heated to such a degree that
we can just hold our hand in it, and the goods are then dyed by the
wince, without heating the bath more till the colouring matter be fixed.
Vitalis prescribes as a mordant, one fourth of alum, and one sixteenth
of tartar; and for dyeing, one third of madder, with the addition of a
24th of solution of tin diluted with its weight of water. He raises the
temperature in the space of an hour, to 200°, and afterwards he boils
for 3 or 4 minutes; a circumstance which is believed to contribute to
the fixation of the colour. The bath, after dyeing, appears much loaded
with yellow matter, because this has less affinity for the alum mordant
than the red. Sometimes a little archil is added to the madder, to give
the dye a pink tinge; but this is fugitive.

Silk is seldom dyed with madder, because cochineal affords brighter
tints.

_Dyeing on cotton and linen._--The most brilliant and fastest madder red
is the Turkey or Adrianople. The common madder reds are given in the
following way:--The yarn or cloth is boiled in a weak alkaline bath,
washed, dried and galled, by steeping the cotton in a decoction of
bruised galls or of sumach. After drying, it is twice alumed; for which
purpose, for every 4 parts of the goods, one part of alum is taken,
mixed with 1-16th of its weight of chalk. The goods are dipped into a
warm solution of the alum, wrung out, dried, and alumed afresh, with
half the quantity. The acetate of alumina mordant, described above,
answers much better than common alum for cotton. After the goods are
dried and rinsed, they are passed through the dye bath, which is formed
of 3/4 lb. of good madder for every pound of cotton; and it is raised to
the boiling point by degrees, in the space of 50 or 60 minutes. Whenever
the ebullition has continued a few minutes, the goods must be removed,
washed slightly, and dyed a second time in the same way, with as much
madder. They are then washed and passed through a warm soap bath, which
removes the dun colouring matter.

Hölterhoff prescribes for ordinary madder red the following
proportions:--20 pounds of cotton yarn; 14 pounds of Dutch madder; 3
pounds of nut-galls; 5 pounds of alum; to which 1/2 lb. of acetate of
lead has been first added, and then a quarter of a pound of chalk.

In the calico-print works the madder goods are passed through a bran
bath first, immediately after dyeing; next, after several days exposure
to the air, when the dun dye has become oxidized, and is more easily
removed. An addition of chalk, on the principles explained above, is
sometimes useful in the madder bath. If bran be added to the madder
bath, the colour becomes much lighter, and of an agreeable shade.
Sometimes bran-water is added to the madder bath, instead of bran.

_Adrianople or Turkey red._--This is the most complicated and tedious
operation in the art of dyeing; but it produces the fastest colour which
is known. This dye was discovered in India, and remained long a process
peculiar to that country. It was afterwards practised in other parts of
Asia and in Greece. In 1747, Ferquet and Goudard brought Greek dyers
into France, and mounted near Rouen, and in Languedoc, Turkey-red dye
works. In 1765, the French government, convinced of the importance of
this business, caused the processes to be published. In 1808, Reber, at
Mariakirch, furnished the finest yarn of this dye, and M. Köchlin became
celebrated for his Turkey-red cloth.

_Process for Turkey-red._--The first step consists in clearing the yarn
or cloth in alkaline baths, and dipping them in oily liquors, to which
sheep’s dung was formerly added. This operation is repeated several
times, the goods being dried after each immersion. There next follows
the cleansing with alkaline liquors to remove the excess of oil, the
galling, the aluming, the maddering, the brightening or removing the dun
part of the dye by boiling, at a high temperature, with alkaline liquid,
and the rosing by boiling in a bath of salt of tin. We shall give some
details concerning this tedious manipulation, and the differences which
exist in it in the principal dye-works.

At Rouen, where the process was first brought to perfection, two methods
are pursued, called the gray and the yellow course or march. In the
gray, the dye is given immediately after the cotton has received the
oily mordant, the gall, and the alum, as it has then a gray colour. In
the yellow course, it is passed through fresh oils, alum, and galls
before the maddering, the cotton having then a yellow tint.

Different views have been taken of the principles of the Turkey red dye,
and the object and utility of the various steps. The most ancient notion
is that of animalizing the cotton by dung and blood, but experience has
proved that without any animal matter the finest colour may be obtained.
According to Dingler, the cotton is imbued with oil by steeping it in
combinations of oil and soda; the oil is altered by repeated dryings at
a high temperature; it attracts oxygen from the air, and thereby
combines intimately with the cotton fibre, so as to increase the weight
of the stuff. The dung, by a kind of fermentation, accelerates the
oxidizement, and hence crude oil is preferable to pure. In England, the
mucilaginous oils of Gallipoli are preferred, and in Malabar, oils more
or less rancid. The drying oils do not answer. The subsequent treatment
with the alkaline liquors removes the excess of oil, which has not been
oxidized and combined; a hard drying completely changes that which
remains in the fibres; the aluming which follows combines alumina with
the cotton; the galling tans the fibres, producing a triple compound of
oil and alum, which fixes the colouring matter. The object of the other
steps is obvious.

According to Wuttich the treatment with oil opens the cotton so as to
admit the mordant and the colouring matter, but the oil and soap do not
combine with the fibres. In the alkaline baths which follow, the oil is
transformed into soap and removed; whence the cotton should not increase
in weight in the galling and aluming; the cotton suffers a kind of
tanning, and the saline parts of the blood assist in fixing the madder
dye.

_The German process improved_, according to Dingler, consists of the
following operations: mordant of an oily soap or a soapy liniment, hard
drying; alkaline bath, drying, steeping, rinsing away of the uncombined
mordant, drying; galling, drying; aluming, drying, steeping in water
containing chalk, rinsing; maddering, airing, rinsing; brightening with
an alkaline boil, and afterwards in a bath containing salt of tin; then
washing and drying.

The yarn or the cloth must be first well worked in a bath of sheep’s
dung and oil, compounded as follows:--25 pounds of sheep’s dung are to
be bruised in a solution of pure caustic potash of hydrometer strength
3°, and the mixed liquor is to be passed through a sieve. Two pounds of
fine oil are now to be poured into 16 pounds of this lye, after which 30
pounds of coarse oil are to be added, with agitation for 1/4 of an hour.
Other 4 pounds of hot lye are to be well stirred in, till the whole is
homogeneous. This proportion of mordant is sufficient for 100 pounds of
cotton yarn, for 90 pounds of unbleached or 100 pounds of bleached
cotton goods. The cotton stuff, after being well wrung out, is to be
laid in a chest and covered with a lid loaded with weights, in which
state it should remain for five days. At the end of 24 hours, the cotton
becomes hot with fermentation, gets imbued with the mordant, and the oil
becomes rapidly altered. The goods are next exposed freely to the air
during the day, and in the evening they are dried in a hot chamber,
exposed to a temperature of 158° F., for 6 or 8 hours, which promotes
the oxidizement of the oil.

The goods are now passed the second time through a soapy-oil mordant
similar to the first, then dried in the air by day, and in the hot stove
by night. The third and fourth oil-soap steeps are given in the same
way, but without the dung. The fifth steep is composed of a lye at 2°,
after which the goods must also be dried. Indeed from the first to the
fourth steep, the cotton stuff should be put each time into a chamber
heated to 145° F. for 12 or 15 hours, and during 18 hours after the
fifth steep.

The uncombined oil must, in the next place, be withdrawn by the
_degraissage_, which consists in steeping the goods for 6 hours in a
very weak alkaline ley. After rinsing and wringing, they are dried in
the air, and then put into the hot stove.

The goods are now galled in a bath formed of 36 pounds of Sicilian
sumach, boiled for 3 hours in 260 pounds of water, and filtered. The
residuum is treated with 190 fresh pounds of water. This decoction is
heated with 12 pounds of pounded nut-galls to the boiling point, allowed
to cool during the night, and used next morning as hot as the hand can
bear; the goods being well worked through it. They are again dried in
the air, and afterwards placed in a stove moderately heated. They are
next passed through a tepid alum bath, containing a little chalk; left
afterwards in a heap during the night, dried in the air, and next in the
stove. The dry goods are finally passed through hot water containing a
little chalk, wrung out, rinsed, and then maddered.

For dyeing, the copper is filled with water, the fire is kindled, and an
ounce and a half of chalk is added for every pound of madder; a pound
and a quarter of madder being taken for every pound of cotton yarn. The
goods are now passed through the bath, so that they penetrate to near
its bottom. The fire must be so regulated, that the copper will begin to
boil in the course of from 2-1/2 to 3 hours; and the ebullition must be
continued for an hour; after which the yarn is aired and rinsed. Cloth
should be put into the dye-bath when its temperature is 77°, and winced
at a heat of from 100° to 122° during the first hour; at 167° during the
second; and at the boiling point when the third hour begins. It is to be
kept boiling for half an hour; so that the maddering lasts four hours.
Dingler does not add sumach or galls to the madder bath, because their
effect is destroyed in the subsequent brightening, and he has no faith
in the utility of blood.

After being dyed, the goods are washed, pressed, and subjected to a
soapy alkaline bath at a high heat, in a close boiler, by which the dun
parts of the galls and the madder are dissolved away, and the red colour
remains in all its lustre. This operation is called brightening. It is
repeated in a similar liquor, to which some muriate of tin is added for
the purpose of enlivening the colour and giving it a rosy tint. Last of
all, the goods are rinsed, and dried in the shade.

The _Elberfeld_ process consists for 100 libs. of the following steps:--

1. Cleaning the cotton by boiling it for four hours in a weak alkaline
bath, cooling and rinsing.

2. Working it thoroughly four times over in a steep, consisting of 300
pounds of water, 15 pounds of potash, 1 pailful of sheep’s dung, and
12-1/2 pounds of olive oil, in which it should remain during the night.
Next day it is drained for an hour, wrung out and dried. This treatment
with the dung steep, and drying, is repeated 3 times.

3. It is now worked in a bath containing 120 quarts of water, 18 pounds
of potash, and 6 quarts of olive oil; then wrung out and dried. This
steep is also repeated 4 times.

4. Steeping for a night in the river is the next process; a slight
rinsing without wringing, and drying in the air.

5. Bath made of a warm decoction (100° F.) of sumach and nut-galls, in
which the goods remain during the night; they are then strongly wrung,
and dried in the air.

6. Aluming with addition of potash and chalk; wringing; working it well
through this bath, where it is left during the night.

7. Draining, and strong rinsing the following day; piling up in a water
cistern.

8. Rinsing repeated next day, and steeping in water to remove any excess
of alum from the fibres; the goods continue in the water till they are
taken to the dyeing-bath.

9. The maddering is made with the addition of blood, sumach, and
nut-galls; the bath is brought to the boil in 1 hour and 3/4, and kept
boiling for half an hour.

10. The yarn is rinsed, dried, boiled from 24 to 36 hours in a covered
copper, with an oily alkaline liquid; then rinsed twice, laid for two
days in clear water, and dried.

11. Finally, the greatest brightness is obtained by boiling for three or
four hours in a soap bath, containing muriate of tin; after which the
yarn is rinsed twice over, steeped in water, and dried.

_Process of Haussmann._--He treats cotton twice or 4 times in a solution
of aluminated potash, mixed with one thirty-eighth part of linseed oil.
The solution is made by adding caustic potash to alum. He dries and
rinses each time, and dries after the last operation. He then rinses and
proceeds to the madder bath. For the rose colour, he takes one pound of
madder for one pound of cotton; for carmine red, he takes from 2 to 3
pounds; and for the deepest red, no less than 4 pounds. It is said that
the colour thus obtained surpasses Turkey red.

_The French process, by Vitalis of Rouen._--First operation. Scouring
with a soda lye, of 1° Baumé, to which there is usually added the
remainder of the _white_ preparation bath, which consists of oil and
soda with water. It is then washed, wrung out, and dried.

In the second operation, he states that from 25 to 30 pounds of sheep’s
dung are commonly used for 100 pounds of cotton yarn. The dung is first
steeped for some days in a lye of soda, of 8° to 10° B. This is
afterwards diluted with about 500 pints of a weaker ley, and at the same
time bruised with the hand in a copper basin whose bottom is pierced
with small holes. The liquor is then poured into a vat containing 5 or 6
pounds of fat oil (Gallipoli), and the whole are well mixed. The cotton
is washed in this, and the hanks of yarn are then stretched on perches
in the open air, and turned from time to time, so as to make it dry
equably. After receiving thus a certain degree of desiccation, it is
carried into the drying house, which is heated to 50° Reaumur (144°
Fahrenheit), where it loses the remainder of its moisture, which would
have prevented it from combining with the other mordants which it is
afterwards to receive. What is left of the bath is called _avances_, and
is added to the following bath. Two, or even three dung baths are given
to the cotton, when it is wished to have very rich colours. When the
cotton has received the dung baths, care must be taken not to leave it
lying in heaps for any length of time, lest it should take fire; an
accident which has occasionally happened.

The white bath is prepared by pouring 6 pounds of fat oil, into 50 pints
of soda water, at 1° or sometimes less, according as, by a preliminary
trial, the oil requires. This bath ought to be repeated two, three, or
even a greater number of times, as more or less body is to be given to
the colour.

To what remains of the white bath, and which is also styled _avances_,
about 100 pints of soda lye of two or three degrees are added. Through
this the cotton is passed as usual. Formerly it was the practice to give
two, or three, or even four oils. Now, two are found to be sufficient.

The cotton is steeped for five or six hours in a tepid solution of soda,
of 1° at most; it is set to drain, is then sprinkled with water, and at
the end of an hour is washed, hank by hank, to purge it entirely from
the oil. What remains of the water of degraissage, serves for the
scouring or first operation.

For 100 pounds of cotton, from 20 to 25 pounds of galls in sorts must be
taken, which are bruised and boiled in about 100 pints of water, till
they crumble easily between the fingers. The galling may be done at two
operations, dividing the above quantity of galls between them, which is
thought to give a richer and more uniform colour.

The aluming of 100 pounds of cotton requires from twenty-five to thirty
pounds of pure alum, that is, alum entirely free from ferruginous salts.
The alum should be dissolved without boiling, in about 100 pints of
river or rain water. When the alum is dissolved, there is to be poured
in a solution of soda, made with the sixteenth part of the weight of the
alum. A second portion of the alkaline solution must not be poured in
till the effervescence caused by the first portion has entirely
ceased,--and so in succession. The bath of saturated alum, being merely
tepid, the cotton is passed through it, as in the gall bath, so as to
impregnate it well, and it is dried with the precautions recommended
above. The dyers who gall at two times, alum also twice, for like
reasons.

For 25 pounds of cotton, 25 pints of blood are prescribed, and 400 pints
of water. Whenever the bath begins to warm, 50 pounds of madder are
diffused through the bath; though sometimes the maddering is given at
two operations, by dividing the madder into two portions.

The brightening bath is prepared always for 100 pounds of cotton, with
from four to five pounds of rich oil, six pounds of Marseilles white
soap, and 600 litres of soda water of 2° B.

The rosing is given with solution of tin, mixed with soap water.

The Turkey-red dye of Messrs. Monteith and Co., of Glasgow, is
celebrated all over the world, and merits a brief description here.

The calico is taken as it comes from the loom without bleaching, for the
natural colour of the cotton wool harmonizes well with the dye about to
be given; it is subjected to a fermentative steep for 24 hours, like
that preliminary to bleaching, after which it is washed at the dash
wheel. It is then boiled in a lye, containing about 1 pound of soda
crystals for 12 pounds of cloth. The oiling process now begins. A bath
is made with 10 gallons of Gallipoli oil, 15 gallon measures of sheep’s
dung not indurated; 40 gallons of solution of soda crystals, of 1·06
specific gravity; 10 gallons of solution of pearl-ash of spec. grav.
1·04; and 140 gallons of water; constituting a milk-white, soapy
solution of about spec. grav. 1·022. This liquor is put into a large
cylindrical vat, and constantly agitated by the rotation of wooden
vanes, which are best constructed on the plan of the mashing apparatus
of a brewery, but far slighter. This saponaceous compound is let off as
wanted by a stopcock into the trough of a padding machine, in order to
imbue every fibre of the cloth in its passage. This impregnation is
still more fully ensured by laying the padded cloth aside in wooden
troughs during 16 or 18 days. The sheep’s dung has been of late years
disused by many Turkey-red dyers both in England and France, but it is
found to be advantageous in producing the very superior colour of the
Glasgow establishment. It is supposed, also, to promote the subsequent
bleaching during the exposure on the green; which is the next process in
favourable weather, but in bad weather the goods are dried over a
hot-flue.

The cloth is padded again with the saponaceous liquor; and again spread
on the grass, or dried hard in the stove. This alternation is repeated a
third time, and occasionally, even a fourth.

The cloth by this time is varnished as it were with oil, and must be
cleansed in a certain degree by being passed through a weak solution of
pearl-ash, at the temperature of about 122° F. It is then squeezed by
the rollers and dried.

A second system of oiling now commences, with the following liquor:--10
gallons of Gallipoli oil; 30 gallons of soda crystals lye, of sp. grav.
1·06; and 10 gallons of caustic potash lye, of specific gravity 1·04,
thoroughly diffused through 170 gallons of water. With this saponaceous
liquor the cloth is padded as before, and then passed between
squeezing-rollers, which return the superfluous liquor into the
padding-trough. The cloth may be now laid on the grass if convenient;
but at any rate it must be hard dried in the stove.

These saponifying, grassing, and drying processes, are repeated three
times; whereby the cloth becomes once more very oleaginous, and must be
cleansed again by steeping in a compound lye of soda crystals and
pearl-ash of the spec. grav. 1·012, at the temperature of 122°. The
cloth is taken out, squeezed between rollers to save the liquor, and
washed. A considerable portion of the mingled alkalis disappear in this
operation, as if they entered into combination with the oil in the
interior of the cotton filaments. The cloth is now hard dried.

_Galling_ is the next great step in the Turkey-red preparation; and for
its success all the oil should have been perfectly saponified.

From 18 to 20 pounds of Aleppo galls (for each 100 libs of cloth) are to
be bruised and boiled for 3 or 4 hours, in 25 gallons of water, till 5
gallons be evaporated; and the decoction is to be then passed through a
searce. Two pounds of sumach may be substituted for every pound of
galls. The goods must be well padded with this decoction, kept at 90°
F., passed through squeezing-rollers, and dried. They are then passed
through a solution of alum of the sp. gr. 1·04, to which a certain
portion of chalk is added to saturate the acid excess of that supersalt;
and in this cretaceous mixture, heated to 110°, the cloth is winced and
steeped for 12 hours. It is then passed between squeezing-rollers, and
dried in the stove.

The _maddering_ comes next.

From two to three pounds of madder, ground to powder in a proper mill,
are taken for every pound of cloth. The cloth, as usual in maddering, is
entered into the cold bath, and winced by the automatic reel during one
hour that the bath takes to boil, and during an ebullition of two hours
afterwards. One gallon of bullock’s blood is added to the cold bath for
every 25 pounds of cloth; being the quantity operated upon in one bath.
The utility of the blood in improving the colour has been ascribed to
its colouring particles; but it is more probably owing to its albuminous
matter combining with the margarates of soda and potash condensed in the
fibres.

As madder contains a dingy brown colouring matter associated with the
fine red, the goods must be subjected to a clearing process to remove
the former tinge, which is more fugitive than the latter. Every hundred
pounds of cloth are therefore boiled during 12 hours at least, with
water containing 5 pounds of soda crystals, 8 pounds of soap, and 16
gallons of the residual pearl-ash and soda-lye of the last cleansing
operation. By this powerful means the dun matter is well nigh removed;
but it is completely so by a second boil, at a heat of 250° F., in a
tight globular copper, along with 5 pounds of soap, and 1 pound of
muriate of tin crystals, dissolved in a sufficient body of water for 100
pounds of cloth. The muriate of tin serves to raise the madder red to a
scarlet hue. A margarate of tin is probably fixed upon the cloth in this
operation.

When the weather permits, the goods should be now laid out for a few
days on the grass. Some manufacturers give them a final brightening with
a weak bath of a chloride of lime; but it is apt to impoverish the
colour.

According to the latest improvements of the French dyers, each of the
four processes of oiling, mordanting, dyeing, and brightening differs,
in some respects, from the above.

1. Their first step is boiling the cloth for four hours, in water
containing one pound of soap for every four pieces. Their saponaceous
bath of a creamy aspect is used at a temperature of 75° F.; and it is
applied by the padding machine 6 times, with the grassing and drying
alternations. In winter, when the goods cannot be exposed on the grass,
no less than 12 alternations of the saponaceous or white bath are
employed, and 8 in spring. They consider the action of the sun-beam to
aid greatly in brightening this dye; but at Midsummer, if it be
continued more than 4 hours, the scarlet colour produced begins to be
impaired.

They conceive that the oiling operation impregnates the fibres with
super-margarate of potash or soda, insoluble salts which attract and
condense the alumina, and the red colouring particles of the madder, so
firmly that they can resist the clearing boil.

2. Their second step, the mordanting, consists first in padding the
pieces through a decoction of galls mixed with a solution of an equal
weight of alum; and after drying in the hot-flue, &c., again padding
them in a solution of an acetate of alumina, made by decomposing a
solution of 16 libs. of alum with 16 libs of acetate of lead, for 6
pieces of cloth, each 32 _aunes_ long.

3. The maddering is given at two successive operations; with 4 pounds of
Avignon madder per piece at each time.

4. The _brightening_ is performed by a 12 hours’ boil in water with soda
crystals, soap, and salt of tin; and the _rosing_ by a 10 hours’ boil
with soap and salt of tin. Occasionally, the goods are passed through a
weak solution of chloride of potash. When the red has too much of a
crimson cast, the pieces are exposed for two days on the grass, which
gives them a bright scarlet tint.

Process of M. Werdet to dye broad cloth and wool by madder:--

“Preparation for 24 pounds of scoured wool:

“Take 4-1/4 pounds of cream of tartar, 4-1/4 pounds of pure alum; boil
the wool gently for 2 hours, transfer it into a cool place, and wash it
next day in clear water.

“_Dyeing._--12 pounds of Avignon madder, infused half an hour at 30° R.
(100° F.) Put into the bath 1 pound of muriate of tin, let the colour
rose for three quarters of an hour at the same heat, and drain or
squeeze the madder through canvas. The whole of the red dye will remain
upon the filter, but the water which has passed through will be as deep
a yellow as a weld bath. The boiler with the dye must now be filled up
with clear river water, and heated to 100° F. Two ounces of the solution
of the tartar and alum must be poured into it, and the wool must be
turned over in it for an hour and a half, while the heat is gradually
raised to the boiling point. The wool is then removed and washed. It
must be rosed the following day.

“_Rosing._--Dissolve in hot water 1 pound of white Marseilles soap; let
the bath cool, and pass the wool through it till it has acquired the
desired shade; 15 or 20 minutes are sufficient. On coming out of this
bath it should be washed.

“_Solution of deuto-muriate of tin_:--

“2 ounces of pure muriatic acid; 4 drachms of pure nitric acid; 1 ounce
of distilled water. Dissolve in it, by small portions at a time, 2
drachms of grain tin, in a large bottle of white glass, shutting it
after putting in the tin. This solution may be preserved for years,
without losing its virtue.”

I have inserted this process, as recently recommended by the French
minister of commerce, and published by M. Pouillet in vol. i. of his
Portefeuille Industriel, to show what _official_ importance is sometimes
given by our neighbours to the most frivolous things.

  Madders imported for home consumption.  Gross amount of Duty paid in
         1836.                1837.           1836.            1837.
  Cwts. 106,172    |   cwts. 79,228      |  _£_10,810    |   _£_8,081


MADREPORES, are calcareous incrustations produced by _polypi_ contained
in cells of greater or less depth, placed at the surface of calcareous
ramifications, which are fixed at their base, and perforated with a
great many pores. The mode of the increase, reproduction and death of
these animals is still unknown to naturalists. Living madrepores are
now-a-days to be observed only in the South American, the Indian, and
the Red seas; but although their polypi are not found in our climate at
present, there can be no doubt of their having existed in these northern
latitudes in former times, since fossil madrepores occur in both the
older and newer secondary strata of Europe.


MAGISTERY, is an old chemical term to designate white pulverulent
substances, spontaneously precipitated in making certain metallic
solutions; as magistery of bismuth.


MAGISTRAL, in the language of the Spanish smelters of Mexico and South
America, is the roasted and pulverized copper pyrites, which is added to
the ground ores of silver in their _patio_, or amalgamation magma, for
the purpose of decomposing the horn silver present. See SILVER, for an
account of this curious process of reduction.


MAGMA, is the generic name of any crude mixture of mineral or organic
matters, in a thin pasty state.


MAGNANIER, is the name given in the southern departments of France to
the proprietor of a nursery in which silk-worms are reared upon the
great scale, or to the manager of the establishment. The word is derived
from _magnans_, which signifies silkworms in the language of the country
people. See SILK.


MAGNESIA (Eng. and Fr.; _Bittererde_, _Talkerde_, Germ.), is one of the
primitive earths, first proved by Sir H. Davy to be the oxide of a
metal, which he called _magnesium_. It is a fine, light, white powder,
without taste or smell, which requires 5150 parts of cold water, and no
less than 36,000 parts of boiling water, for its solution. Its specific
gravity is 2·3. It is fusible only by the heat of the hydroxygen
blowpipe. A natural hydrate is said to exist which contains 30 per cent.
of water. Magnesia changes the purple infusion of red cabbage to a
bright green. It attracts carbonic acid from the air, but much more
slowly than quicklime. It consists of 61·21 parts of metallic basis, and
38·79 of oxygen; and has, therefore, 20 for its prime equivalent upon
the hydrogen scale. Its only employment in the arts is for the
purification of fine oil, in the preparation of varnish.

Magnesia may be obtained by precipitation with potash or soda, from its
sulphate, commonly called Epsom salt; but it is usually procured by
calcining the artificial or natural carbonate. The former is, properly
speaking, a subcarbonate, consisting of 44·69 magnesia, 35·86 carbonic
acid, and 19·45 water. It is prepared by adding to the solution of the
sulphate, or the muriate (the _bittern_ of sea-salt evaporation works),
a solution of carbonate of soda, or of carbonate of ammonia distilled
from bones in iron cylinders. The sulphate of magnesia is generally made
by acting upon magnesian limestone with somewhat dilute sulphuric acid.
The sulphate of lime precipitates, while the sulphate of magnesia
remains in solution, and may be made to crystallize in quadrangular
prisms, by suitable evaporation and slow cooling. Where muriatic acid
may be had in profusion for the trouble of collecting it, as in the soda
works in which sea salt is decomposed by sulphuric acid, the magnesian
limestone should be first acted upon with as much of the former acid as
will dissolve out the lime, and then, the residuum being treated with
the latter acid, will afford a sulphate at the cheapest possible rate;
from which magnesia and all its other preparations may be readily made.
Or, if the equivalent quantity of calcined magnesian limestone be boiled
for some time in bittern, the lime of the former will displace the
magnesia from the muriatic acid of the latter. This is the most
economical process for manufacturing magnesia. The subcarbonate, or
_magnesia alba_ of the apothecary, has been proposed by Mr. E. Davy to
be added by the baker to damaged flour, to counteract its acescency.


MAGNESIAN LIMESTONE (_Dolomie_, Fr.; _Bittertalk_, _Talkspath_, Germ.),
is a mineral which crystallizes in the rhombohedral system. Spec. grav.
2·86; scratches calc-spar; does not fall spontaneously into powder, when
calcined, as common limestone does. It consists of 1 prime equivalent of
carbonate of lime = 50, associated with 1 of carbonate of magnesia = 42.

_Massive magnesian limestone_, is yellowish-brown, cream-yellow, and
yellowish-gray; brittle. It dissolves slowly and with feeble
effervescence in dilute muriatic acid; whence it is called _Calcaire
lent dolomie_ by the French mineralogists. Specific gravity 2·6 to 2·7.

Near Sunderland, it is found in flexible slabs. The principal range of
hills composing this geological formation in England, extends from
Sunderland on the northeast coast to Nottingham, and its beds are
described as being about 300 feet thick on the east of the coal field in
Derbyshire, which is near its southern extremity. On the western side of
the Cumberland mountains magnesian limestone overlies the coal measures
near Whitehaven. The stratification of this rock is very distinct, the
individual courses of stone not exceeding in general the thickness of a
common brick.

The lime resulting from the calcination of magnesian limestone appears
to have an injurious action on vegetation, unless applied in quantities
considerably less than common lime, when it is found to fertilize the
soil. After two years, its hurtful influence on the ground seems to
become exhausted, even when used in undue quantity. Great quantities of
it are annually brought from Sunderland to Scotland by the Fifeshire
farmers, and employed beneficially by them, as a manure, in preference
to other kinds of lime. It has been unfairly denounced by Mr. Tennent
and Sir H. Davy, as a sterilizer.

This rock is used in many places for building; indeed our most splendid
monument of Gothic architecture, York Minster, is constructed of
magnesian limestone.


MAGNESIA, NATIVE (_Brucite_; _Guhr magnésien_, Fr.; _Wassertalk_,
Germ.), is a white, lamellar, pearly-looking mineral, soft to the touch.
Spec. grav. 2·336; tender; scratched by calc-spar; affording water by
calcination; leaving a white substance which browns turmeric paper; and,
by calcination with nitrate of cobalt, becoming of a lilac hue. It
consists of 69·75 magnesia, and 30·25 water. It occurs in veins in the
serpentine at Hoboken, in New Jersey, as also at Swinaness, in the
island of Unst, Shetland.


MAGNESITE, _Giobertite_; native carbonate of magnesia, occurs in white,
hard, stony masses, in the presidency of Madras, and in a few other
localities. It dissolves very slowly in muriatic acid, and gives out
carbonic acid in the proportion of 22 parts by weight to 42 of the
mineral, according to my experiments, and is therefore an atomic
carbonate. It forms an excellent and beautiful mortar cement for
terraces; a purpose to which it has been beneficially applied in India
by Dr. Macleod.


MAGNET, NATIVE, is a mineral consisting of the protoxide and peroxide of
iron combined in equivalent proportions. See IRON.


MAHALEB. The fruit of this shrub affords a violet dye, as well as a
fermented liquor like _Kirschwasser_. It is a species of cherry
cultivated in our gardens.


MALACHITE, or _mountain green_, is native carbonate of copper of a
beautiful green colour, with variegated radiations and zones; spec.
grav. 3·5; it scratches calc-spar, but not fluor; by calcination it
affords water and turns black. Its solution in the acids, deposits
copper upon a plate of iron plunged into it. It consists of carbonic
acid 18·5; deutoxide of copper 72·2; water 9·3.


MALATES, are saline compounds of the bases, with


MALIC ACID. (_Acide malique_, Fr.; _Aepfelsäure_, Germ.) This acid
exists in the juices of many fruits and plants, alone, or associated
with the citric, tartaric, and oxalic acids; and occasionally combined
with potash or lime. Unripe apples, sloes, barberries, the berries of
the mountain ash, elder berries, currants, gooseberries, strawberries,
raspberries, bilberries, brambleberries, whortleberries, cherries,
ananas, afford malic acid; the house-leek and purslane contain the
malate of lime.

The acid may be obtained most conveniently from the juice of the berries
of the mountain ash, or barberries. This must be clarified, by mixing
with white of egg, and heating the mixture to ebullition; then
filtering, digesting the clear liquor with carbonate of lead, till it
becomes neutral; and evaporating the saline solution, till crystals, of
malate of lead be obtained. These are to be washed with cold water, and
purified by re-crystallization. On dissolving the white salt in water,
and passing a stream of sulphuretted hydrogen through the solution, the
lead will be all separated in the form of a sulphuret, and the liquor,
after filtration and evaporation, will yield yellow granular crystals,
or cauliflower concretions, of malic acid, which may be blanched by
re-dissolution and digestion with bone-black, and re-crystallization.

Malic acid has no smell, but a very sour taste, deliquesces by
absorption of moisture from the air, is soluble in alcohol, fuses at
150° Fahr., is decomposed at a heat of 348°, and affords by distillation
a peculiar acid, the pyromalic. It consists in 100 parts, of 41·47
carbon; 3·51 hydrogen; and 55·02 oxygen; having nearly the same
composition as citric acid. A crude malic acid might be economically
extracted from the fruit of the mountain ash, applicable to many
purposes; but it has not hitherto been manufactured upon the great
scale.


MALLEABILITY, is the property belonging to certain metals, of being
extended under the hammer. A table of malleability is given in the
article DUCTILITY.


MALT; (Eng. and Fr.; _Malz_, Germ.) is barley-corn, which has been
subjected to an artificial process of germination. See BEER.

Table of the Quantity of Malt consumed by the undermentioned Brewers of
London and Vicinity, from October 10th, 1836, to October 10th, 1837.

  +--------------------------------+-------+
  |             Brewers.           |  Qrs. |
  +--------------------------------+-------+
  |Barclay and Co.                 | 100005|
  |Hanbury and Co.                 |  82798|
  |Whitbread and Co.               |  47012|
  |Reid and Co.                    |  43945|
  |Combe and Co.                   |  40366|
  |Hoare and Co.                   |  32347|
  |Calvert and Co.                 |  32335|
  |Meux and Co.                    |  30575|
  |Elliot and Co.                  |  24154|
  |Taylor and Co.                  |  23556|
  |Charrington and Co.             |  18842|
  |Thorne and Son                  |  16404|
  |Gardner                         |  15256|
  |Ramsbottom and Co.              |  15227|
  |J. & C. Goding (11 months)      |  14023|
  |Bricheno                        |   9863|
  |Courage and Co.                 |   9284|
  |Wood and Co.                    |   7834|
  |Goding, Thos.                   |   7095|
  |Hazard                          |   6674|
  |Mann, Jas.                      |   6588|
  |Harris, Thos.                   |   6042|
  |More                            |   6025|
  |M’Leod, B.                      |   4960|
  |Farren and Till                 |   4783|
  |Manners and Co.                 |   4552|
  |Hale, George.                   |   4547|
  |Halford and Topham              |   3786|
  |Stains and Fox                  |   5783|
  |Lamont and Co.                  |   3600|
  |Laxton                          |   3583|
  |Richmond                        |   3174|
  |Maynard                         |   3133|
  |M’Leod and Thompson             |   2834|
  |Tubb                            |   2826|
  |Johnson and Wyatt               |   2809|
  |Duggan and Co.                  |   2665|
  |Hodgson                         |   2400|
  |Sherborn and Co.                |   2347|
  |Griffith                        |   2221|
  |Cox, John                       |   2151|
  |Masterman                       |   1914|
  |Hill and Rice                   |   1853|
  |Gray and Dacre                  |   1760|
  |Plimmer                         |   1747|
  |Hayward                         |   1737|
  |Verey, W. and C.                |   1573|
  |Williamson and Co.              |   1566|
  |Honeyball                       |   1512|
  |Satchell and Son                |   1441|
  |Clarke, C.                      |   1330|
  |Colyer                          |   1299|
  |Filmer and Wall                 |   1298|
  |Nicholls and Co.                |   1240|
  |Hagan                           |   1143|
  |Hume                            |   1126|
  |Buckley and Co.                 |   1025|
  |Verey, J.                       |   1017|
  |Collins, J.                     |    966|
  |Jones                           |    956|
  |Ufford and Oldershaw            |    953|
  |Blogg, B.                       |    943|
  |Ing                             |    900|
  |Keep                            |    886|
  |Soulby                          |    861|
  |Clarke, R.                      |    834|
  |Jenner                          |    833|
  |Manvell                         |    824|
  |M’Leods                         |    820|
  |Braithwaite                     |    799|
  |Addison                         |    768|
  |Turner                          |    766|
  |Holt                            |    756|
  |Church                          |    742|
  |Clarke, S.                      |    741|
  |Mann, Joel                      |    733|
  |Turner                          |    712|
  |Mantell                         |    693|
  |Lock                            |    651|
  |Hood                            |    649|
  |Pink, A.                        |    636|
  |Collins                         |    598|
  |Wright                          |    588|
  |West                            |    565|
  |Abbott                          |    560|
  |Hett (6 months)                 |    552|
  |Wells                           |    520|
  |Higgs                           |    475|
  |Harris, Robt.                   |    470|
  |Woodward                        |    462|
  |Wicks                           |    441|
  |Bell                            |    440|
  |Thompson                        |    406|
  |Mattam                          |    400|
  |M’Intosh                        |    397|
  |Thurlby                         |    392|
  |Griffiths                       |    391|
  |Kay                             |    360|
  |Tidman                          |    332|
  |Lindsay                         |    326|
  |Cooper                          |    315|
  |West                            |    306|
  |Carpenter                       |    299|
  |Green                           |    292|
  |Chapman                         |    286|
  |Brace                           |    266|
  |Clark                           |    248|
  |Allen                           |    245|
  |Powditch                        |    238|
  |Garnett                         |    232|
  |Hill                            |    222|
  |Olley                           |    214|
  |Ward                            |    206|
  |Bye                             |    201|
  |Newton                          |    175|
  |Chadwick                        |    169|
  |Prosser                         |    166|
  |Smith                           |    164|
  |Edwards                         |    156|
  |Pugh                            |    155|
  |Hainstock                       |    155|
  |Lloyd                           |    154|
  |Reynolds                        |    151|
  |Latham                          |    142|
  |Meaton                          |    140|
  |Brewer                          |    135|
  |Stirling                        |    133|
  |Ambler                          |    130|
  |Potter                          |    122|
  |Champion                        |    121|
  |Miller                          |    115|
  |Edwards                         |    108|
  |Easton                          |    105|
  |Griffiths                       |    105|
  |Hopkins                         |     91|
  |Hudson                          |     90|
  |Thorpe                          |     89|
  |Burt                            |     88|
  |Bowden                          |     88|
  |Batt                            |     84|
  |Phillips                        |     83|
  |Jewit                           |     82|
  |Tyler                           |     76|
  |Whittaker                       |     75|
  |Begbie                          |     75|
  |Carter                          |     75|
  |Priddle                         |     74|
  |Coomber                         |     73|
  |Stallwood                       |     71|
  |Jones                           |     71|
  |Rose                            |     67|
  |Norris                          |     67|
  |Remnant                         |     62|
  |Kearney                         |     62|
  |Smith                           |     62|
  |Woodroffe                       |     60|
  |Knight                          |     60|
  |Graves                          |     54|
  |Sheppard                        |     52|
  |Field                           |     51|
  |Bradfield                       |     51|
  |Webb                            |     50|
  |Chapman                         |     48|
  |Price                           |     45|
  |Godfrey                         |     45|
  |Hobbs                           |     32|
  |Denman                          |     31|
  +--------------------------------+-------+
  |                                   Qrs. |
  |Quantity used     1836,          754,313|
  |Quantity used     1837,          714,488|
  |                                 -------|
  |      Decrease    1837,           39,825|
  |                                 -------|
  |         JOHN SLATER, _Cask Inspector_. |
  |_Hop-Duty_, 1837. (_Old_) _£_178,578.   |
  |3_s._ 0-1/2_d._                         |
  +----------------------------------------+

Table of the Quantity of Malt from Barley, which paid Duty in

  +------+----------+---------+---------+
  |Years.| England. |Scotland.| Ireland.|
  +------+----------+---------+---------+
  |      | Bushels. | Bushels.| Bushels.|
  |1834. |34,949,646|3,580,758|1,776,883|
  |1835. |36,078,855|3,604,816|1,825,300|
  |1836. |37,196,998|4,168,854|1,872,104|
  |                                     |
  |      Amount of Duties paid:         |
  |      |   _£_    |    _£_  |    _£_  |
  |1834. | 4,449,745|  462,514|  229,514|
  |1835. | 4,660,185|  465,622|  235,767|
  |1836. | 4,804,612|  538,477|  241,813|
  +------+----------+---------+---------+

[Illustration: 653 654 655]


MALT KILN; (_Darre_, Germ.) The improved malt kiln of Pistorius is
represented _fig._ 653. in a top view; _fig._ 654. in a longitudinal
view and section; and _fig._ 655., in transverse section. _a a_, are two
quadrangular smoke flues, constructed of fire-tiles, or fire-stones, and
covered with iron plates, over which a pent-house roof is laid; the
whole bound by the cross pieces _b_ (_figs._ 654, 655.) These flues are
built above a grating _c c_, which commences at _c´_; in front of _c´_
there is a bridge of bricks. Instead of such a brick flue covered with
plates, iron pipes may be used, covered with semi-cylindrical tiles, to
prevent the malt that may happen to fall from being burned. _d d_, are
the breast walls of the kiln, 3 feet high, furnished with two apertures
shut with iron doors, through which the malt that drops down may be
removed from time to time. _e_ is a beam of wood lying on the breast
wall, against which the hurdles are laid down slantingly towards the
back wall of the kiln; _f f_, are two vertical flues left in the
substance of the walls, through which the hot air, discharged by open
pipes laid in a subjacent furnace, rises into the space between the
pent-house roof and the iron plates, and is thence allowed to issue
through apertures in the sides. _g_ is the discharge flue in the back
wall of the kiln for the air now saturated with moisture; _h_ is the
smoke-pipe, from which the smoke passes into the anterior flue _a_,
provided with a slide-plate, for modifying the draught; the smoke thence
flows off through a flue fitted also with a damper-plate into the
chimney _i_. _k_ is the smoke-pipe of a subsidiary fire, in case no
smoke should pass through _h_. The iron pipes are 11 inches in diameter,
the air-flue _f_, 5 inches, and the smoke-pipe _h_, 10 inches square;
the brick flues 10 inches wide, and the usual height of bricks.


MALTHA; _Bitume Glutineux_, or mineral pitch. It is a soft glutinous
substance, with the smell of pitch. It dissolves in alcohol, but leaves
a bituminous residuum; as also in naphtha, and oil of turpentine. It
seems to be inspissated petroleum.


MANGANESE, (Eng. and Fr.; _Mangan_, _Braunsteinmetal_, Germ.) is a
grayish-white metal, of a fine-grained fracture, very hard, very
brittle, with considerable lustre, of spec. grav. 8·013, and requiring
for fusion the extreme heat of 160° Wedgewood. It should be kept in
closely stoppered bottles, under naphtha, like potassium, because with
contact of air it speedily gets oxidized, and falls into powder. It
decomposes water slowly at common temperatures, and rapidly at a red
heat. Pure oxide of manganese can be reduced to the metallic state only
in small quantities, by mixing it with lamp black and oil into a dough,
and exposing the mixture to the intense heat of a smith’s forge, in a
luted crucible; which must be shaken occasionally to favour the
agglomeration of the particles into a button. Thus procured, it
contains, however, a little carbon.

Manganese is susceptible of five degrees of oxigenation:--

1. The _protoxide_ may be obtained from a solution of the sulphate by
precipitation with carbonate of potash, and expelling the carbonic acid
from the washed and dried carbonate, by calcination in a close vessel
filled with hydrogen gas, taking care that no air have access during the
cooling. It is a pale green powder, which slowly attracts oxygen from
the air, and becomes brown; on which account it should be kept in glass
tubes, containing hydrogen, and hermetically sealed. It consists of
77·57 metal and 22·43 oxygen. It forms with 24 per cent. of water a
white hydrate; and with acids, saline compounds; which are white, pink,
or amethyst coloured. They have a bitter, acerb taste, and afford with
hydrogenated sulphuret of ammonia, a flesh-red precipitate, but with
caustic alkalis, one which soon turns brown-red, and eventually black.

2. The _deutoxide of manganese_ exists native in the mineral called
_Braunite_; but it may be procured either by calcining, at a red heat,
the proto-nitrate, or by spontaneous oxidizement of the protoxide in the
air. It is black; when finely pulverized, dark brown, and is
convertible, on being heated in acids, into protoxide, with
disengagement of oxygen gas. It consists of 69·75 metal, and 30·25
oxygen. It forms with 10 per cent. of water, a liver-brown hydrate,
which occurs native under the name of _Manganite_. It dissolves readily
in tartaric and citric acids, but in few others. This oxide constitutes
a bronze ground in calico-printing.

3. _Peroxide of manganese_; _Braunstein_, occurs abundantly in nature.
It gives out oxygen freely when heated, and becomes an oxidulated
deutoxide. It consists of 63·36 metal, and 36·64 oxygen.

4. _Manganesic acid_, forms green-coloured salts, but has not hitherto
been insulated from the bases. It consists of 53·55 metal, and 46·45
oxygen.

5. _Hypermanganesic acid_, consists of 49·70 metal, and 50·30 oxygen.

_Ores of manganese._--There are two principal ores of this metal which
occur in great masses; the peroxide and the hydrated oxide; the first of
which is frequently found in primitive formations.

1. _Metalloide oxide of manganese_; _pyrolusite_, or gray manganese ore;
has a metallic lustre, a steel gray colour, and affords a black powder.
Spec. grav. 4·85. Scratches calc-spar. It effervesces briskly with borax
at the blow-pipe, in consequence of the disengagement of oxygen gas.
This is the most common ore of manganese, and a very valuable one, being
the substance mostly employed in the manufacture of chloride of lime and
of flint-glass. It is the peroxide. Great quantities are found near
Tavistock, in Devonshire, and Launceston, in Cornwall.

2. _Braunite_, is a dark brown substance, of a glassy metallic lustre,
affording a brown powder. Spec. grav. 4·8. It scratches felspar; but is
scratched by quartz. Infusible at the blow-pipe, and effervesces but
slightly when fused with glass of borax. It is the deutoxide. It gives
out at a red heat only 3 per cent. of oxygen.

3. _Manganite_, or hydroxide of manganese; is brownish-black or
iron-black, powder brown, with somewhat of a metallic lustre. Spec.
grav. 4·3. Scratches fluor spar; affords water by calcination in a glass
tube; infusible at the blow-pipe; and effervesces slightly when fused
with glass of borax. It consists of about 90 of deutoxide, and 10 of
water.

4. _Haussmanite_, _black braunstein_; is brownish-black, affords a
reddish-brown powder. Spec. grav. 4·7; scratches fluor spar; infusible
at the blow-pipe; does not effervesce when fused with borax. It is a
deutoxide. This is a rare mineral, and of no value to the arts.

5. _Barytic oxide of manganese_; _fibrous wad_. It is a combination of
deutoxide and peroxide, with some baryta.

6. _Manganese blende_, or sulphuret of manganese; has a metallic aspect;
is black, or dark steel gray; spec. grav. 3·95; has no cleavage; cannot
be cut; infusible, but affords after being roasted distinct evidence of
manganese, by giving a violet tinge to soda at the blow-pipe. Soluble in
nitric acid; solution yields a white precipitate with the ferro-cyanide
of potassium. It consists of sulphur 53·65; manganese 66·35.

7. _Carbonate of manganese_; _dialogite_. Spec. grav. 3·4; affords a
green frit by fusion with carbonate of soda; is soluble with some
effervescence in nitric acid; solution when freed from iron by succinate
of ammonia, gives a white precipitate, with ferrocyanide of potassium.
It consists of 28 carbonic acid, 56 protoxide of manganese, 5·4 of lime,
4·5 protoxide of iron, and 0·8 magnesia.

8. _Hydrosilicate of manganese_; is a black metallic looking substance,
which yields a yellowish-brown powder, and water by calcination; is
acted upon by muriatic acid, but affords no chlorine. It consists of
silica 25; protoxide of manganese 60; water 13.

9. _Ferriferous phosphate of manganese_, is brown or black. Spec. grav.
3·6; scratches fluor; affords by calcination a very little of an acid
water which corrodes glass; very fusible at the blow-pipe into a black
metalloid magnetic bead; is acted upon by nitric acid: solution lets
fall a blue precipitate with ferrocyanide of potassium; which tested by
soda is shown to be manganese. It consists of phosphoric acid 32·78;
protoxide of iron 31·90; protoxide of manganese 32·60; phosphate of lime
3·2. Another phosphate called _hureaulite_, contains 38 of phosphoric
acid; 11·10 of protoxide of iron; 32·85 of protoxide of manganese, and
18 of water.

_Black wad_, is the old English name of the hydrated peroxide of
manganese. It occurs in various imitative shapes, in froth-like coatings
upon other minerals, as also massive. Some varieties possess imperfect
metallic lustre. The external colour is brown of various shades, and
similar in the streak, only shining. It is opaque, very sectile, soils
and writes. Its specific gravity is about 3·7. Mixed with linseed oil
into a dough, black wad forms a mass that spontaneously inflames. A
variety from the Hartz, analyzed by Klaproth, afforded peroxide of
manganese 68; oxide of iron 6·5; water 17·5; carbon 1; barytes and
silica 9. The localities of black wad are particularly Cornwall and
Devonshire, the Hartz, and Piedmont. I have analyzed many varieties of
the black wad sold to the manufacturers of bleaching salt, and flint
glass, and have found few of them so rich in peroxide of manganese as
the above. Very generally they contained no less than 25 _per cent._ of
oxide of iron, 8 or 9 of silica, about 7 of water, and the remainder
amounting to only 60 _per cent._ of the peroxide.

M. Gay Lussac has proposed to determine the commercial value of
manganese ore, by the quantity of chlorine which it affords when treated
with liquid muriatic acid. He places the manganese powder in a small
retort or matras, pours over it the acid, and the chlorine being
disengaged with the aid of a gentle heat, is transmitted into a vessel
containing milk of lime or potash water. This liquor is thereafter
poured into a dilute solution of sulphate of indigo; and the quantity
of chlorine is inferred from the quantity of the blue solution which is
decoloured. I pass the chlorine into test solution of indigo.

The manufacturer of flint glass uses a small proportion of the black
manganese ore, to correct the green tinge which his glass is apt to
derive from the iron present in the sand he employs. To him it is of
great consequence to get a native manganese containing as little iron
oxide as possible; since in fact the colour or limpidity of his product
will depend altogether upon that circumstance.

Sulphate of manganese has been of late years introduced into calico
printing, to give a chocolate or bronze impression. It is easily formed
by heating the black oxide, mixed with a little ground coal, with
sulphuric acid. See CALICO PRINTING.

The peroxide of manganese is used also in the formation of glass pastes,
and in making the black enamel of pottery. See OXALIC ACID.


MANGLE. (_Calandre_, Fr.; _Mangel_, Germ.) This is a well known machine
for smoothing table cloths, table napkins, as well as linen and cotton
furniture. As usually made, it consists of an oblong rectangular wooden
chest, filled with stones, which load it to the degree of pressure that
it should exercise upon the two cylinders on which it rests, and which,
by rolling backwards and forwards over the linen spread upon a polished
table underneath, render it smooth and level. The moving wheel, being
furnished with teeth upon both surfaces of its periphery, and having a
notch cut out at one part, allows a pinion, uniformly driven in one
direction, to act alternately upon its outside and inside, so as to
cause the reciprocating motion of the chest. This elegant and much
admired English invention, called the mangle-wheel, has been introduced
with great advantage into the machinery of the textile manufactures.

Mr. Warcup, of Dartford, obtained a patent several years ago for a
mangle, in which the linen, being rolled round a cylinder revolving in
stationary bearings, is pressed downwards by heavy weights hung upon its
axes, against a curved bed, made to slide to and fro, or traverse from
right to left, and left to right, alternately.

Mr. Hubie, of York, patented in June, 1832, another form of mangle,
consisting of three rollers, placed one above another in a vertical
frame, the axle of the upper roller being pressed downwards by a
powerful spring. The articles intended to be smoothed are introduced
into the machine by passing them under the middle roller, which is made
to revolve by means of a fly wheel; the pinion upon whose axis works in
a large toothed wheel fixed to the shaft of the same roller. The linen,
&c. is lapped as usual in protecting cloths. This machine is merely a
small CALENDER.


MANIOC, is the Indian name of the nutritious matter of the shrub
_jatropha manihot_, from which _cassava_ and _tapioca_ are made in the
West Indies.


MANNA, is the concrete saccharine juice of the _Fraxinus ornus_, a tree
much cultivated in Sicily and Calabria. It is now little used, and that
only in medicine.


MARBLE. This title embraces such of the primitive, transition, and purer
compact limestones of secondary formation, as may be quarried in solid
blocks without fissures, and are susceptible of a fine polished surface.
The finer the white, or more beautifully variegated the colours of the
stone, the more valuable, _ceteris paribus_, is the marble. Its general
characters are the following:--

Marble effervesces with acids; affords quicklime by calcination; has a
conchoidal scaly fracture; is translucent only on the very edges; is
easily scratched by the knife; has a spec. grav. of 2·7; admits of being
sawn into slabs; and receives a brilliant polish. These qualities occur
united in only three principal varieties of limestone; in the saccharoid
limestone, so called from its fine granular texture resembling that of
loaf sugar, and which constitutes modern statuary marble, like that of
Carrara; 2. in the foliated limestone, consisting of a multitude of
small facets formed of little plates applied to one another in every
possible direction, constituting the antique statuary marble, like that
of Paros; 3. in many of the transition and carboniferous, or
_encrinitic_ limestones, subordinate to the coal formation.

The saccharoid and lamellar, or statuary marbles, belong entirely to
primitive and transition districts. The greater part of the
close-grained coloured marbles belong also to the same geological
localities; and become so rare in the secondary limestone formations,
that immense tracts of these occur without a single bed sufficiently
entire and compact to constitute a workable marble. The limestone lying
between the calcareo-siliceous sands and gritstone of the under oolite,
and which is called Forest marble in England, being susceptible of a
tolerable polish, and variegated with imbedded shells, has sometimes
been worked into ornamental slabs in Oxfordshire, where it occurs in the
neighbourhood of Whichwood forest; but this case can hardly be
considered as an exception to the general rule. To constitute a
profitable marble-quarry, there must be a large extent of homogeneous
limestone, and a facility of transporting the blocks after they are dug.
On examining these natural advantages of the beds of Carrara marble, we
may readily understand how the statuary marbles discovered in the
Pyrenees, Savoy, Corsica, &c. have never been able to come into
competition with it in the market. In fact, the two sides of the valley
of Carrara may be regarded as mountains of statuary marble of the finest
quality.

Gypseous alabaster may be readily distinguished from marbles, because it
does not effervesce with acids, and is soft enough to be scratched by
the nail; stalagmitic alabaster is somewhat harder than marble,
translucent, and variegated with regular stripes or undulations.

Some granular marbles are flexible in thin slabs, or, at least, become
so by being dried at the fire; which shews, as Dolomieu suspected, that
this property arises from a diminution of the attractive force among the
particles, by the loss of the moisture.

The various tints of ornamental marbles generally proceed from oxides of
iron; but the blue and green tints are sometimes caused by minute
particles of hornblende, as in the slate-blue variety called Turchino,
and in some green marbles of Germany. The black marbles are coloured by
charcoal, mixed occasionally with sulphur and bitumen; when they
constitute stinkstone.

Brard divides marbles, according to their localities, into classes, each
of which contains eight subdivisions:--

1. Uni-coloured marbles; including only the white and the black.

2. Variegated marbles; those with irregular spots or veins.

3. Madreporic marbles, presenting animal remains in the shape of white
or gray spots, with regularly disposed dots and stars in the centre.

4. Shell marbles; with only a few shells interspersed in the calcareous
base.

5. Lumachella marbles, entirely composed of shells.

6. Cipolin marbles, containing veins of greenish talc.

7. Breccia marbles, formed of a number of angular fragments of different
marbles, united by a common cement.

8. Puddingstone marbles; a conglomerate of rounded pieces.

_Antique marbles._--The most remarkable of these are the
following:--_Parian marble_, called _lychnites_ by the ancients, because
its quarries were worked by lamps; it has a yellowish-white colour; and
a texture composed of fine shining scales, lying in all directions. The
celebrated Arundelian tables at Oxford consist of Parian marble, as well
as the Medicean Venus. _Pentelic marble_, from Mount Penteles, near
Athens, resembles the Parian, but is somewhat denser and finer grained,
with occasional greenish zones, produced by greenish talc, whence it is
called by the Italians _Cipolino statuario_. The Parthenon, Propyleum,
the Hippodrome, and other principal monuments of Athens, were of
Pentelic marble; of which fine specimens may be seen among the Elgin
collection, in the British Museum. _Marmo Greco_, or Greek white marble,
is of a very lively snow white colour, rather harder than the preceding,
and susceptible of a very fine polish. It was obtained from several
islands of the Archipelago, as Scio, Samos, Lesbos, &c. _Translucent
white marble_, _Marmo statuario_ of the Italians, is very much like the
Parian, only not so opaque. Columns and altars of this marble exist in
Venice, and several towns of Lombardy; but the quarries are quite
unknown. _Flexible white marble_, of which five or six tables are
preserved in the house of Prince Borghese, at Rome. The _White marble of
Luni_, on the coast of Tuscany, was preferred by the Greek sculptors to
both the Parian and Pentelic. _White marble of Carrara_, between Specia
and Lucca, is of a fine white colour, but often traversed by gray veins,
so that it is difficult to procure moderately large pieces free from
them. It is not so apt to turn yellow as the Parian marble. This quarry
was worked by the ancients, having been opened in the time of Julius
Cæsar. Many antique statues remain of this marble. Its two principal
quarries at the present day are those of Pianello and Polvazzo. In the
centre of its blocks very limpid rock-crystals are sometimes found,
which are called Carrara diamonds. As the finest qualities are becoming
excessively rare, it has risen in price to about 3 guineas the cubic
foot. The _White marble_ of Mount Hymettus, in Greece, was not of a very
pure white, but inclined a little to gray. The statue of Meleager, in
the French Museum, is of this marble.

_Black antique marble_, the _Nero antico_ of the Italians. This is more
intensely black than any of our modern marbles; it is extremely scarce,
occurring only in sculptured pieces. The _red antique marble_, _Egyptum_
of the ancients, and _Rosso antico_ of the Italians, is a beautiful
marble of a deep blood-red colour, interspersed with white veins and
with very minute white dots, as if strewed over with grains of sand.
There is in the Grimani palace at Venice, a colossal statue of Marcus
Agrippa in _rosso antico_, which was formerly preserved in the Pantheon
at Rome. _Green antique marble_, _verde antico_, is a kind of breccia,
whose paste is a mixture of talc and limestone, while the dark green
fragments consist of serpentine. Very beautiful specimens of it are
preserved at Parma. The best quality has a grass-green paste, with black
spots of noble serpentine, but is never mingled with red spots. _Red
spotted green antique marble_, has a dark green ground marked with small
red and black spots, with fragments of _entrochi_ changed into white
marble. It is known only in small tablets. _Leek marble_; a rare variety
of that colour, of which there is a table in the Mint at Paris. _Marmo
verde pagliocco_ is of a yellowish green colour, and is found only in
the ruins of ancient Rome. _Cervelas marble_ of a deep red, with
numerous gray and white veins, is said to be found in Africa, and highly
esteemed in commerce. _Yellow antique marble_, _giallo antico_ of the
Italians; colour of the yolk of an egg, either uniform or marked with
black or deep yellow rings. It is rare, but may be replaced by Sienna
marble. _Red and white antique marbles_, found only among the ruins of
ancient Rome. _Grand antique_, a breccia marble, containing shells,
consists of large fragments of a black marble, traversed by veins or
lines of a shining white. There are four columns of it in the Museum at
Paris. _Antique Cipolino marble._ Cipolin is a name given to all such
marbles as have greenish zones produced by green talc; their fracture is
granular and shining, and displays here and there plates of talc.
_Purple antique breccia marble_, is very variable in the colour and size
of its spots. _Antique African breccia_, has a black ground, variegated
with large fragments of a grayish-white, deep red, or purplish wine
colour; and is one of the most beautiful marbles. _Rose-coloured antique
breccia_ marble is very scarce, occurring only in small tablets. There
are various other kinds of ancient breccias, which it would be tedious
to particularize.

_Modern marbles._--1. British. Black marble is found at Ashford,
Matlock, and Monsaldale in Derbyshire; black and white in the north part
of Devonshire; the variegated marbles of Devonshire are generally
reddish, brownish, and grayish, variously veined with white and yellow,
or the colours are often intimately blended; the marbles from Torbay and
Babbacombe, display a great variety in the mixture of their colours; the
Plymouth marble is either ash-coloured with black veins, or
blackish-gray and white, shaded with black veins; the cliffs near
Marychurch exhibit marble quarries not only of great extent, but of
superior beauty to any other in Devonshire, being either of a
dove-coloured ground with reddish-purple and yellow veins, or of a black
ground mottled with purplish globules. The green marble of Anglesea is
not unlike the _verde antico_; its colours being greenish-black,
leek-green, and sometimes dull purplish, irregularly blended with white.
The white part is limestone, the green shades proceed from serpentine
and asbestos. There are several fine varieties of marble in Derbyshire;
the mottled-gray in the neighbourhood of Moneyash, the light gray being
rendered extremely beautiful by the number of purple veins which spread
upon its polished surface in elegant irregular branches; but its chief
ornament is the multitude of _entrochi_, with which this transition
limestone-marble abounds. Much of the transition and carboniferous
limestone of Wales and Westmoreland is capable of being worked up into
agreeable dark marbles.

In Scotland, a particularly fine variety of white marble is found in
immense beds, at Assynt in Sutherlandshire. A beautiful ash-gray marble
of a very uniform grain, and susceptible of a fine polish, occurs on the
north side of the ferry of Ballachulish in Invernesshire. One of the
most beautiful varieties is that from the hill of Belephetrich in Tiree,
one of the Hebrides. Its colours are pale blood-red, light flesh-red,
and reddish-white, with dark green particles of hornblende, or rather
sahlite, diffused through the general base. The compact marble of Iona
is of a fine grain, a dull white colour, somewhat resembling pure
compact felspar. It is said by Bournon, to consist of an intimate
mixture of tremolite and carbonate of lime, sometimes with yellowish or
greenish-yellow spots. The carboniferous limestone of many of the coal
basins in the lowlands of Scotland may be worked into a tolerably good
marble for chimney-pieces.

In Ireland, the Kilkenny marble is the one best known, having a black
ground more or less varied with white marks produced by petrifactions.
The spar which occupies the place of the shells, sometimes assumes a
greenish-yellow colour. An exceedingly fine black marble has also been
raised at Crayleath in the county of Down. At Louthlougher, in the
county of Tipperary, a fine purple marble is found, which when polished
looks very beautiful. The county of Kerry affords several variegated
marbles, not unlike the Kilkenny.

France possesses a great many marble quarries which have been described
by Brard, and of which a copious abstract is given under the article
marble,--_Rees’ Cyclopedia_.

The territory of Genoa furnishes several beautiful varieties of marble,
the most remarkable of which is the _polzevera di Genoa_, called in
French the _vert d’Egypte_ and _vert de mer_. It is a mixture of
granular limestone with a talcose and serpentine substance disposed in
veins; and it is sometimes mixed with a reddish body. This marble was
formerly much employed in Italy, France, and England, for
chimney-pieces, but its sombre appearance has put it out of fashion.

Corsica possesses a good statuary marble of a fine close grain, and pure
milky whiteness, quarried at Ornofrio; it will bear comparison with that
of Carrara; also a gray marble (_bardiglio_), a cipolin, and some other
varieties. The island of Elba has immense quarries of a white marble
with blackish-green veins.

Among the innumerable varieties of Italian marbles, the following
deserve especial notice.

The _rovigio_, a white marble found at Padua; the white marble of St.
Julien, at Pisa, of which the cathedral and celebrated slanting tower
are built; the Biancone marble, white with a tinge of gray, quarried at
Magurega for altars and tombs. Near Mergozza the white saline marble
with gray veins is found, with which the cathedral of Milan is built.
The black marble of Bergamo is called _paragone_, from its black colour,
like touchstone; it has a pure intense tint, and is susceptible of a
fine polish. The pure black marble of Como is also much esteemed. The
_polveroso_ of Pistoya, is a black marble sprinkled with dots; and the
beautiful white marble with black spots, from the Lago Maggiore, has
been employed for decorating the interior of many churches in the
Milanese. The Margorre marble found in several parts of the Milanese, is
bluish veined with brown, and composes part of the dome of the cathedral
of Milan. The green marble of Florence owes its colour to a copious
admixture of steatite. Another green marble, called _verde di Prado_,
occurs in Tuscany, near the little town of Prado. It is marked with
spots of a deeper green than the rest, passing even into blackish-blue.
The beautiful Sienna marble, or _brocatello di Siena_, has a yellow
colour like the yolk of an egg, which is disposed in large irregular
spots, surrounded with veins of bluish-red, passing sometimes into
purple. At Montarenti, two leagues from Sienna, another yellow marble is
met with, which is traversed by black and purplish-black veins. The
Brema marble is yellow with white spots. The _mandelato_ of the Italians
is a light red marble with yellowish-white spots, found at Luggezzana,
in the Veronese. The red marble of Verona is of a red rather inclining
to yellow or hyacinth; a second variety of a dark red, composes the vast
amphitheatre of Verona. Another marble is found near Verona, with large
white spots in a reddish and greenish paste. Very fine columns have been
made of it. The _occhio di pavone_ is an Italian shell marble, in which
the shells form large orbicular spots, red, white, and bluish. A
madreporic marble known under the name of _pietra stellaria_, much
employed in Italy, is entirely composed of star madrepores, converted
into a gray and white substance, and is susceptible of an excellent
polish. The village of Bretonico, in the Veronese, furnishes a splendid
breccia marble, composed of yellow, steel-gray, and rose-coloured spots.
That of Bergamo consists of black and gray fragments in a greenish
cement. Florence marble, called also ruin and landscape marble, is an
indurated calcareous marl.

Sicily abounds in marbles, the most valuable of which is that called by
the English stone-cutters, Sicilian jasper; it is red with large stripes
like ribands, white, red, and sometimes green, which run zigzag with
pretty acute angles.

Among the Genoese marbles we may notice the highly esteemed variety
called _portor_, on account of the brilliant yellow veins in a deep
black ground. The most beautiful kind comes from Porto-Venese, and Louis
XIV. caused a great deal of it to be worked up for the decoration of
Versailles. It costs now two pounds per cubic foot.

_Of cutting and polishing marble._--The marble saw is a thin plate of
soft iron, continually supplied during its sawing motion, with water and
the sharpest sand. The sawing of moderate pieces is performed by hand,
but that of large slabs is most economically done by a proper mill.

The first substance used in the polishing process is the sharpest sand,
which must be worked with till the surface becomes perfectly flat. Then
a second, and even a third sand of increasing fineness is to be applied.
The next substance is emery of progressive degrees of fineness, after
which tripoli is employed; and the last polish is given with tin-putty.
The body with which the sand is rubbed upon the marble, is usually a
plate of iron; but for the subsequent process, a plate of lead is used
with fine sand and emery. The polishing rubbers are coarse linen cloths,
or bagging, wedged tight into an iron planing tool. In every step of the
operation, a constant trickling supply of water is required.

Visiters of Derby may have an opportunity of inspecting Brown’s
extensive machinery for cutting marble into many ornamental forms, which
has been well described in Rees’ Cyclopedia.

Sir James Jelf patented, in 1822, a combination of machinery for cutting
any description of parallel mouldings upon marble slabs, for ornamental
purposes; in which, tools, supplied with sand and water, are made to
traverse to and fro.

Mr. Tullock obtained a patent, in 1824, for improvements in machinery
for sawing and grooving marble; the power being applied by means of
toothed wheels bearing cranks, which gave the see-saw motion to the
cutting iron plates.

In November, 1829, Mr. Gibbs secured, by patent, an invention for
working ornamental devices in marble, by means of a travelling drill,
guided by a mould of wood, &c., in counter relief; and in April, 1833,
Mr. G. W. Wilds obtained a patent for machinery, which consists of a
series of circular cutters, for separating slabs from a block of marble;
the block being advanced slowly to meet the cutters, by the progressive
movement of a platform upon wheels, driven by the agency of a rack and
pinion, as in the cylinder boring machine of the steam-engine
manufacturer. Sand and water must be supplied, of course, from a hopper,
to these smooth cutting discs of iron or copper. See GLASS-CUTTING. He
proposes also to mould and polish marble, by applying a rotatory wheel
or cylinder of any shape to it, in its carrying frame.


MARCASITE, is a variety of iron pyrites, containing generally a little
arsenic.


MARGARATES, are saline compounds of margaric acid with the bases.


MARGARIC ACID, is one of the acid fats, produced by saponifying tallow
with alkaline matter, and decomposing the soap with dilute acid. The
term Margaric signifies PEARLY-looking.

The physical properties of the margaric and stearic acids are very
similar; the chief difference is that the former is more fusible,
melting at 140° F. The readiest mode of obtaining pure margaric acid, is
to dissolve olive oil soap in water, to pour into the solution, a
solution of neutral acetate of lead, to wash and dry the precipitate,
and then to remove its oleate of lead by ether, which does not affect
its margarate of lead. The residuum being decomposed by boiling hot
muriatic acid, affords margaric acid. When heated in a retort this acid
boils. It is insoluble in water, very soluble in alcohol and ether; it
reddens litmus paper, and decomposes with the aid of heat, the
carbonates of soda and potash.


MARINE ACID. See MURIATIC ACID.


MARINE SALT. See SALT.


MARL (_Marne_, Fr.; _Mergel_, Germ.), is a mixed earthy substance,
consisting of carbonate of lime, clay, and siliceous sand, in very
variable proportions; it is sometimes compact, sometimes pulverulent.
According to the predominance of one or other of these three main
ingredients, marls may be distributed into calcareous, clayey, and
sandy. See LIMESTONE.


MARQUETRY, is a peculiar kind of cabinet work, in which the surface of
wood is ornamented with inlaid pieces of various colours and forms. The
_marqueteur_ puts gold, silver, copper, tortoise-shell, mother-of-pearl,
ivory, horn, &c. under contribution. These substances being reduced to
laminæ of proper thinness, are cut out into the desired forms by
punches, which produce at once the full pattern or mould, and the empty
one, which enclosed it; and both serve their separate purposes in
marquetry. For the methods of dyeing the woods, &c. see IVORY.


MARTIAL, signifies belonging to iron; from Mars, the mythological name
of this metal.


MASSICOT, is the yellow oxide of lead.


MASTIC (Eng. and Fr.; _Mastix_, Germ.), is a resin produced by making
incisions in the _Pistacia Lentiscus_, a tree cultivated in the Levant,
and chiefly in the island of Chios. It comes to us in yellow, brittle,
transparent, rounded tears; which soften between the teeth; with
bitterish taste and aromatic smell, and a specific gravity of 1·07.
Mastic consists of two resins; one soluble in dilute alcohol; but both
dissolve in strong alcohol. Its solution in spirit of wine constitutes a
good varnish. It dissolves also in oil of turpentine. See VARNISH.


MATRASS, is a bottle with a thin egg-shaped bottom, much used for
digestions in chemical researches.


MATTE, is a crude black copper reduced, but not refined from sulphur and
other heterogeneous substances.


MEADOW ORE, is conchoidal bog iron ore.


MEDALS. For their composition, see BRONZE and COPPER.


MEERSCHAUM (Germ.; _sea-froth_, Eng.; _Ecume de Mer_, _Magnésie
carbonatée silicifère_, Fr.), is a white mineral, of a somewhat earthy
appearance, always soft, but dry to the touch, and adhering to the
tongue. Specific gravity, 2·6 to 3·4; affords water by calcination;
fuses with difficulty at the blowpipe into a white enamel; and is acted
upon by acids. It consists, according to Klaproth, of silica, 41·5;
magnesia, 18·25; water and carbonic acid, 39. Other analysts give,
silica 50, magnesia 25, water 25. It occurs in veins or kidney-shaped
nodules, among rocks of serpentine, at Egribos, in the island of
Negropont, Eski-Schehir in Anatolia, Brussa at the foot of Mount
Olympus, at Baldissero in Piedmont, in the serpentine veins of Cornwall,
&c.

When first dug up, it is soft, greasy, and lathers like soap; and is on
that account used by the Tartars in washing their linen. The well-known
Turkey tobacco-pipes are made from it, by a process analogous to that
for making pottery ware. The bowls of the pipes, when imported into
Germany, are prepared for sale by soaking them first in tallow, then in
wax, and finally by polishing them with shave-grass.


MELLITE. (Eng. and Fr.; _Honigstein_, Germ.) See HONEYSTONE.


MELLITIC ACID, which is associated with alumina in the preceding
mineral, crystallizes in small colourless needles, is without smell, of
a strongly acid taste, permanent in the air, soluble in water and
alcohol, as also in boiling hot concentrated sulphuric acid, but is
decomposed by hot nitric acid, and consists of 50·21 carbon, and 49·79
oxygen. It is carbonized at a red heat, without the production of any
inflammable oil.


MELLON, is a new compound of carbon and azote, discovered by M. Liebig,
by heating bi-sulpho-cyanide of mercury. The mellon remains at the
bottom of the retort under the form of a yellow powder.


MENACHANITE, an ore of _titanium_, found in the bed of a rivulet which
flows into the valley Menacan, in Cornwall.


MERCURY or QUICKSILVER. This metal is distinguished by its fluidity at
common temperatures; its density = 13·6; its silver blue lustre; and its
extreme mobility. A cold of 39° below zero of Fahrenheit, or -40° cent.,
is required for its congelation, in which state its density is increased
in the proportion of 10 to 9, or it becomes of spec. grav. 15·0. At a
temperature of 656° F. it boils and distils off in an elastic vapour;
which, being condensed by cold, forms purified mercury.

Mercury combines with great readiness with certain metals, as gold,
silver, zinc, tin, and bismuth, forming, in certain proportions, fluid
solutions of these metals. Such mercurial alloys are called _amalgams_.
This property is extensively employed in many arts; as in extracting
gold and silver from their ores; in gilding, plating, making
looking-glasses, &c. Humboldt estimates at 16,000 quintals, of 100 lbs.
each, the quantity of mercury annually employed at his visit to America,
in the treatment of the mines of New Spain; three-fourths of which came
from European mines.

The mercurial ores may be divided into four species:--

1. _Native quicksilver._--It occurs in most of the mines of the other
mercurial ores, in the form of small drops attached to the rocks, or
lodged in the crevices of other ores.

2. _Argental mercury, or native silver amalgam._--It has a silver-white
colour, and is more or less soft, according to the proportion which the
mercury bears to the silver. Its density is sometimes so high as 14. A
moderate heat dissipates the mercury, and leaves the silver. Klaproth
states its constituents at silver 36, and mercury 64, in 100; but
Cordier makes them to be, 27-1/2 silver, and 72-1/2 mercury. It occurs
crystallized in a variety of forms. It has been found in the territory
of Deux-Ponts, at Rozenau and Niderstana, in Hungary, in a canton of
Tyrol, at Sahlberg in Sweden, at Kolyvan in Siberia, and at Allémont in
Dauphiny; in small quantity at Almaden in Spain, and at Idria in
Carniola. By the chemical union of the mercury with the silver, the
amalgam, which should by calculation have a spec. grav. of only 12·5,
acquires that of 14·11, according to M. Cordier.

3. _Sulphuret of mercury_, commonly called Cinnabar, is a red mineral of
various shades; burning at the blowpipe with a blue flame, volatilizing
entirely with the smell of burning sulphur, and giving a quicksilver
coating to a plate of copper held in the fumes. Even the powder of
cinnabar rubbed on copper whitens it. Its density varies from 6·9 to
10·2. It becomes negatively electrical by friction. Analysed by
Klaproth, it was found to consist of mercury 84·5, sulphur 14·75. Its
composition, viewed as a bisulphuret of mercury, is, mercury 86·2,
sulphur 13·8. The finest crystals of sulphuret of mercury come from
China, and Almaden in Spain. These contain, according to Klaproth, 85
per cent. of mercury.

A _bituminous sulphuret of mercury_ appears to be the base of the great
exploration of Idria; it is of a dark liver-red hue; and of a slaty
texture, with straight or twisted plates. It exists in large masses in
the bituminous schists of Idria. M. Beurard mentions also the locality
of Munster-Appel, in the duchy of Deux-Ponts, where the ore includes
impressions of fishes, curiously spotted with cinnabar.

The compact variety of the Idria ore seems very complex in composition,
according to the following analysis of Klaproth:--Mercury, 81·8;
sulphur, 13·75; carbon, 2·3; silica, 0·65; alumina, 0·55; oxide of iron,
0·20; copper, 0·02; water, 0·73; in 100 parts. M. Beurard mentions
another variety from the Palatinate, which yields a large quantity of
bitumen by distillation; and it was present in all the specimens of
these ores analyzed by me for the German Mines Company. At Idria and
Almaden the sulphurets are extremely rich in mercury.

4. _Muriated mercury_, or the _Chloride of mercury_, commonly called
Horn mercury. This ore occurs in very small crystals of a pearl-gray or
greenish-gray colour, or in small nipples which stud, like crystals, the
cavities, fissures, or geodes among the ferruginous gangues of the other
ores of mercury. It is brittle, and entirely volatile at the blowpipe,
characters which distinguish it from horn silver.

The geological position of the mercurial ores, in all parts of the
world, is in the strata which commence the series of secondary
formations. Sometimes they are found in the red sandstone above the
coal, as at Menildot, in the old dutchy of Deux-Ponts, at Durasno in
Mexico, at Cuença in New Granada, at Cerros de Gauzan and Upar in Peru;
in the subordinate porphyries, as at Deux-Ponts, San Juan de la Chica in
Peru, and at Cerro-del-Fraile, near the town of San-Felipe, they occur
also among the strata below, or subordinate to the calcareous formation,
called _zechstein_, in Germany, or among the accompanying bituminous
schists, as at Idria in Carniola; and, lastly, they form masses in the
zechstein itself. Thus, it appears that the mercurial deposits are
confined within very narrow geological limits, between the calcareous
beds of zechstein, and the red sandstone. They occur at times in
carbonaceous nodules, derived from the decomposition of mosses of
various kinds; and the whole mercurial deposit is occasionally covered
with beds of charcoal, as at Durasno.

They are even sometimes accompanied with the remains of organic bodies,
such as casts of fishes, fossil shells, silicified wood, and true coal.
The last fact has been observed at Potzberg, in the works of
Drey-Koenigszug, by M. Brongniart. These sandstones, bituminous schists,
and indurated clays, contain mercury both in the state of sulphuret and
in the native form. They are more or less penetrated with the ore,
forming sometimes numerous beds of very great thickness; while, in the
more antient or the primitive formations, these ores exist only in very
small quantity associated with tin. Mercury is, generally speaking, a
metal sparingly distributed in nature, and its mines are very rare.

The great exploitations of Idria in Friuli, in the county of Goritz,
were discovered in 1497, and the principal ore mined there is the
bituminous sulphuret. The workings of this mine have been pushed to the
depth of 280 yards. The product in quicksilver might easily amount
annually to 6000 metric quintals = 600 tons British; but, in order to
uphold the price of the metal, the Austrian government has restricted
the production to 150 tons. The memorable fire of 1803 was most
disastrous to these mines. It was extinguished only by drowning all the
underground workings. The sublimed mercury in this catastrophe
occasioned diseases and nervous tremblings to more than 900 persons in
the neighbourhood.

Pliny has recorded two interesting facts: 1. that the Greeks imported
red cinnabar from Almaden 700 years before the Christian era; and 2.
that Rome, in his time, annually received 700,000 pounds from the same
mines. Since 1827, they have produced 22,000 cwts. of mercury every
year, with a corps of 700 miners and 200 smelters; and, indeed, the
veins are so extremely rich, that though they have been worked pretty
constantly during so many centuries, the mines have hardly reached the
depth of 330 yards, or something less than 1000 feet. The lode actually
under exploration is from 14 to 16 yards thick, and it becomes thicker
still at the crossing of the veins. The totality of the ore is
extracted. It yields in their smelting works only 10 per cent. upon an
average, but there is no doubt, from the analysis of the ores, that
nearly one half of the quicksilver is lost, and dispersed in the air, to
the great injury of the workmen’s health, in consequence of the
barbarous apparatus of aludels employed in its sublimation; an apparatus
which has remained without any material change for the better since the
days of the Moorish dominion in Spain. M. Le Play, the eminent
_Ingenieur des Mines_, who published, in a recent volume of the Annales
des Mines, his _Itinéraire_ to Almaden, says, that the mercurial
contents of the ores are _notablement plus elevées_ than the product.

These veins extend all the way from the town of Chillon to Almadenejos.
Upon the borders of the streamlet Balde Azogues, a black slate is also
mined which is abundantly impregnated with metallic mercury. The ores
are treated in 13 double furnaces, which I shall presently describe. “Le
mercure,” says M. Le Play, “a sur la santé des ouvriers la plus funeste
influence, et l’on ne peut se défendre d’un sentiment pénible en voyant
l’empressement avec lequel des jeunes gens, pleins de force et de santé,
se disputent la faveur d’aller chercher dans les mines, des maladies
cruelles, et souvent une mort prématurée. La population des mineurs
d’Almaden méritent le plus haut interêt.” These victims of a deplorable
mismanagement are described as being a laborious, simple-minded,
virtuous race of beings, who are thus condemned to breathe an atmosphere
impregnated far and near with the fumes of a volatile poison, which the
lessons of science, as I shall presently demonstrate, might readily
repress, with the effect of not only protecting the health of the
population, but of vastly augmenting the revenues of the state.

These celebrated mines, near to which lie those of _Las Cuebas_ and of
_Almadenejos_, were known to the Romans. After having been the property
of the religious knights of _Calatrava_, who had assisted in expelling
the Moors, they were farmed off to the celebrated _Fugger_ merchants of
Augsbourg; and afterwards explored on account of the government, from
the date of 1645 till the present time. Their produce was, till very
lately, entirely appropriated to the treatment of the gold and silver
ores of the new world.

The mines of the _Palatinate_, situated on the left bank of the Rhine,
though they do not approach in richness and importance to those of Idria
and Almaden, merit, however, all the attention of the government that
farms them out. They are numerous, and varied in geological position.
Those of Drey-Koenigszug, at Potzberg, near Kussel, deserve particular
notice. The workings have reached a depth of more than 220 yards; the
ore being a sandstone strongly impregnated with sulphuret of mercury.
The produce of these mines is estimated at about 30 tons per annum.

There are also in Hungary, Bohemia, and several other parts of Germany,
some inconsiderable exploitations of mercury, the total produce of which
is valued at about 30 or 40 tons on an average of several years.

The mines of Guancavelica, in Peru, are the more interesting, as their
products are directly employed in treating the ores of gold and silver,
which abound in that portion of America. These quicksilver mines,
explored since 1570, produced, up to 1800, 53,700 tons of that metal;
but the actual produce of the explorations of these countries was,
according to Helms, about the beginning of this century, from 170 to 180
tons per annum.

In 1782 recourse was had by the South American miners to the mercury
extracted in the province of Yun-nan, in China.

The metallurgic treatment of the quicksilver ores is tolerably simple.
In general, when the sulphuret of mercury, the most common ore, has been
pulverized, and sometimes washed, it is introduced into retorts of cast
iron, sheet iron, or even stoneware, in mixture with an equal weight of
quicklime. These retorts are arranged in various ways.

Prior to the 17th century, the method called _per descensum_ was the
only one in use for distilling mercury; and it was effected by means of
two earthen pots adjusted over each other. The upper pot, filled with
ore, and closed at the top, was covered over with burning fuel; and the
mercurial vapours expelled by the heat, passed down through small holes
in the bottom of the pot, to be condensed in another vessel placed
below. However convenient this apparatus might be, on account of the
facility of transporting it, wherever the ore was found, its
inefficiency and the losses it occasioned were eventually recognized.
Hence, before 1635, some smelting works of the Palatinate had given up
the method _per descensum_, which was, however, still retained in Idria;
and they substituted for it the furnaces called _galleries_. At first
earthenware retorts were employed in these furnaces; but they were soon
succeeded by iron retorts. In the Palatinate this mode of operating is
still in use. At Idria, in the year 1750, a great distillatory apparatus
was established for the treatment of the mercurial ores, in imitation of
those which previously existed at Almaden, in Spain, and called
_aludel-furnaces_. But, since 1794, these aludels have been suppressed,
and new distillatory apparatus have been constructed at Idria,
remarkable only for their magnitude; exceeding, in this respect, every
other metallurgic erection.

There exist, therefore, three kinds of apparatus for the distillation of
mercury: 1. the furnace called a _gallery_; 2. the furnace with
_aludels_; and 3. the _large apparatus_ of Idria. I shall describe each
of these briefly, in succession.

[Illustration: 656 657 658]

1. _Furnace called Gallery of the Palatinate._--The construction of this
furnace is disposed so as to contain four ranges, _a a´_, _b b´_, of
large retorts, styled cucurbits, of cast iron, in which the ore of
mercury is subjected to distillation. This arrangement is shewn in
_fig._ 656., which presents a vertical section in the line _a b_ of the
ground plan, _fig._ 657. In the ground plan, the roof _e e´_ of the
furnace (_fig._ 656.) is supposed to be lifted off, in order to shew the
disposition of the four ranges of cucurbits upon the grate _c f_,
_figs._ 656, 657., which receives the pit-coal employed as fuel. Under
this grate extends an ash-pit _d_. _Fig._ 658., which exhibits an
elevation of the furnace, points out this ash-pit, as well as one of the
two doors _c_, by which the fuel is thrown upon the grate _c f_.
Openings _e e_, (_fig._ 656.) are left over the top arch of the furnace,
whereby the draught of air may receive a suitable direction. The grate
of the fire-place extends over the whole length of the furnace, _fig._
657., from the door _c_ to the door _f_, situated at the opposite
extremity. The furnace called _gallery_ includes commonly 30 cucurbits,
and in some establishments even 52. Into each are introduced from 56 to
70 pounds of ore, and 15 to 18 pounds of quicklime, a mixture which
fills no more than two-thirds of the cucurbit; to the neck a stoneware
receiver is adapted, containing water to half its height. The fire, at
first moderate, is eventually pushed till the cucurbits are red hot. The
operation being concluded, the contents of the receivers are poured out
into a wooden bowl placed upon a plank above a bucket; the quicksilver
falls to the bottom of the bowl, and the water draws over the _black
mercury_, for so the substance that coats the inside of the receivers is
called. This is considered to be a mixture of sulphuret and oxide of
mercury. The _black mercury_, taken out of the tub and dried, is
distilled anew with excess of lime; after which the residuum in the
retorts is thrown away, as useless.

[Illustration: 659 660]

_Aludel furnaces of Almaden._--_Figs._ 659. and 660. represent the great
furnaces with aludels in use at Almaden, and anciently in Idria; for
between the two establishments there was in fact little difference
before the year 1794. _Figs._ 659. and 662. present two vertical
sections; _figs._ 660. and 661. are two plans of two similar furnaces,
conjoined in one body of brickwork. In the four figures the following
objects are to be remarked; a door _a_, by which the wood is introduced
into the fire-place _b_. This is perforated with holes for the passage
of air; the ash-pit _c_, is seen beneath. An upper chamber _d_, contains
the mercurial ores distributed upon open arches, which form the
perforated sole of this chamber. Immediately over these arches, there
are piled up in a dome form, large blocks of a limestone, very poor in
quicksilver ore; above these are laid blocks of a smaller size, then
ores of rather inferior quality, and stamped ores mixed with richer
minerals. Lastly, the whole is covered up with soft bricks, formed of
clay kneaded with _schlich_, and with small pieces of sulphuret of
mercury. Six ranges of aludels or stoneware tubes, _f f_, of a pear
shape, luted together with clay, are mounted in front of each of the two
furnaces, on a double sloping terrace, having in its lowest middle line
two gutters _t v_, a little inclined towards the intermediate wall _m_.
In each range the aludel placed at the line _t m v_ of _fig._ 660., that
is to say at the lowest point, _g_, _figs._ 659. 662., is pierced with a
hole. Thereby the mercury which had been volatilized in _d_, if it be
already condensed by the cooling in the series of aludels _f g_, may
pass into the corresponding gutter, next into the hole _m_, _fig._ 660.,
and after that into the wooden pipes _h h´_, _fig._ 659., which conduct
it across the masonry of the terrace into cisterns filled with water;
see _q_, _fig._ 661., which is the plan of _fig._ 662.

[Illustration: 661 662]

The portion of mercury not condensed in the range of aludels, _f g_,
which is the most considerable, goes in the state of vapour, into a
chamber _k_; but in passing under a partition _l l_, a certain portion
is deposited in a cistern _i_, filled with water. The greater part of
the vapours diffused in the chamber _k´_ is thereby condensed, and the
mercury falls down upon the two inclined planes which form its bottom.
What may still exist as vapour passes into an upper chamber _k´_, by a
small chimney _n_. On one of the sides of this chamber there is a
shutter which may be opened at pleasure from below upwards, and beneath
this shutter, there is a gutter into which a notable quantity of mercury
collects. Much of it is also found condensed in the aludels. These facts
prove that this process has inconveniences, which have been tried to be
remedied by the more extensive but rather unchemical grand apparatus of
Idria.

Details of the aludel apparatus: 25 are set in each of the 12 ranges,
seen in _fig._ 661. constituting 300 pear-shaped stoneware vessels, open
at both ends, being merely thrust into one another, and luted with loam.
What a multitude of joints, of which a great many must be continually
giving way by the shrinkage of the luting, whereby the mercurial fumes
will escape with great loss of product, to poison the air!

_a_, is the door of the fire-place; _c_, the perforated arches upon
which the ore is piled in the chamber _e_, through the door _d_, and an
orifice at top; the latter being closed during the distillation; _f f_
are vents for conducting the mercurial vapours into two chambers _i_,
separated by a triangular body of masonry _m n_; _h_ is the smoke
chimney of the fire-place; _o o_, are the ranges of aludels, in
connection with the chamber _i_, which are laid slantingly towards the
gutter _q_, upon the double inclined plane terrace, and terminate in the
chamber _h q_; this being surmounted by two chimneys _t_. The mercury is
collected in these aludels and in the basins at _q_ and _p_, _fig._ 661.
_r_ is a thin stone partition set up between the two principal walls of
each of the furnaces. _v_ is the stair of the aludel terrace, leading to
the platform which surmounts the furnace; _z_ is a gutter for conducting
away the rains which may fall upon the buildings.

_Great apparatus of Idria._--Before entering into details of this
laboratory, it will not be useless to recapitulate the metallurgic
classification of the ores treated in it. 1. The ores in large blocks,
fragments, or shivers, whose size varies from a cubic foot to that of a
nut. 2. The smaller ores, from the size of a nut to that of grains of
dust.

The first class of _large_ ores comprises three subdivisions, namely;
_a_, blocks of metalliferous rocks, which is the most abundant and the
poorest species of ore, affording only one _per cent._ of mercury; _b_,
the massive sulphuret of mercury, the richest and rarest ore, yielding
80 _per cent._ when it is picked; _c_, the fragments or splinters
proceeding from the breaking and sorting, and which vary in value, from
1 to 40 _per cent._

The second class of small ores comprises: _d_, the fragments or shivers
extracted from the mine in the state of little pieces, affording from 10
to 12 _per cent._; _e_, the kernels of ore, separated on the sieve,
yielding 32 _per cent._; _f_, the sands and paste called _schlich_,
obtained in the treatment of the poorest ores, by means of the stamps
and washing tables; 100 parts of this _schlich_ give at least 8 of
quicksilver.

The general aspect of the apparatus is indicated by _figs._ 663, 664.
and 665. _Fig._ 665. represents the exterior, but only one half, which
is enough, as it resembles exactly the other, which is not shown. In
these three figures the following objects may be distinguished; _figs._
663, 664., _a_, door of the fire-place; _b_, the furnace in which
beech-wood is burned mixed with a little fir-wood; _c_, door of the
ash-pit, extended beneath; _d_, a space in which the ores are deposited
upon the seven arches, 1. to 7., as indicated in _figs._ 663. and 666.;
_e e_, brick tunnels, by which the smoke of the fuel and the vapours of
mercury pass, on the one side, into successive chambers _f k_.

[Illustration: 663 664]

_f g h i j k l_ are passages which permit the circulation of the vapours
from the furnace _a b c d_, to the chimneys _l l_. _Figs._ 663. and 664.
exhibit clearly the distribution of these openings on each side of the
same furnace, and in each half of the apparatus, which is double, as
_fig._ 664. shows; the spaces without letters being in every respect
similar to the spaces mentioned below. _Fig._ 664. is double the scale
of _fig._ 663.

[Illustration: 665]

_m m´_, _fig._ 664., are basins of reception, distributed before the
doors of each of the chambers _f k f´ k´_. The condensed mercury which
flows out of the chambers is conveyed thither. _n n´_ is a trench into
which the mercury, after being lifted into the basins _m_, is poured, so
that it may run towards a common chamber _o_, in the sloping direction
indicated by the arrows. _o_ leads to the chamber where the mercury is
received into a porphyry trough; out of which it is laded and packed up
in portions of 50 or 100 lbs. in sheep-skins prepared with alum. _p p´_,
_fig._ 663., are vaulted arches, through which a circulation may go on
round the furnace _a b c d_, on the ground level, _q q´_ are the vaults
of the upper stories. _r r´_, _fig._ 665., vaults which permit access to
the tunnels _e´ e´´_, _fig._ 663.

[Illustration: 666]

_s s´_ and _t t´_, _fig._ 665., are the doors of the chambers, _f k_ and
_f´ k´_. These openings are shut during the distillation by wooden doors
faced with iron, and luted with a mortar of clay and lime. _u u´_ is the
door of the vaults 1. to 7. of the furnace represented in _fig._ 663.
These openings are hermetically shut, like the preceding. _v v´_, _fig._
663., are superior openings of the chambers, closed during the operation
by luted plugs; they are opened afterwards to facilitate the cooling of
the apparatus, and to collect the mercurial soot. _x y z_, _fig._ 666.,
are floors which correspond to the doors _u u´_ of the vaults 1. to 7.,
_fig._ 665. These floors are reached by stairs set up in the different
parts of the building, which contains the whole apparatus.

On the lower arches the largest blocks of metalliferous rock are laid;
over these the less bulky fragments are arranged, which are covered with
the shivers and pieces of less dimension. On the middle vaults, the
small ore is placed, distributed into cylindrical pipkins of
earthenware, of 10 inches diameter and 5 inches depth. The upper vaults
receive likewise pipkins filled with the sands and pastes called
_schlich_.

In 3 hours, by the labour of 40 men, the two double sets of apparatus
are charged, and all the apertures are closed. A quick fire of
beech-wood is then kindled; and when the whole mass has become
sufficiently heated, the sulphuret of mercury begins to vapourize;
coming into contact with the portion of oxygen which had not been
carbonated, by combustion, its sulphur burns into sulphurous acid, while
the mercury becomes free, passes with the other vapours into the
chambers for condensing it, and precipitates in the liquid form at a
greater or less distance from the fire-place. The walls of the chambers
and the floors, with which their lower portion is covered, are soon
coated over with a black mercurial soot, which, being treated anew,
furnishes 50 _per cent._ of mercury. The distillation lasts from 10 to
12 hours; during which time the whole furnace is kept at a cherry-red
heat. A complete charge for the two double apparatus, consists of from
1000 to 1300 quintals of ore, which produce from 80 to 90 quintals of
running mercury. The furnace takes from 5 or 6 days to cool, according
to the state of the weather; and if to that period be added the time
requisite for withdrawing the residuums, and attending to such repairs
as the furnace may need, it is obvious that only one distillation can be
performed in the course of a week.

In the works of Idria, in 1812, 56,686 quintals and a half of
quicksilver ores were distilled, after undergoing a very careful
mechanical preparation. They afforded 4832 quintals of running mercury;
a quantity corresponding to about 8-1/2 _per cent._ of the ore. These
smelting works are about 180 feet long and 30 feet high.

Upon the preceding three systems of smelting mercurial ores, I shall now
make some observations.

It has been long well known, that quicksilver may be most readily
extracted from cinnabar, by heating it in contact with quicklime. The
sulphur of the cinnabar combines, by virtue of a superior affinity with
the lime, to the exclusion of the quicksilver, to form sulphurets of
lime and calcium, both of which being fixed _hepars_, remain in the
retort while the mercury is volatilized by the heat. In a few places,
hammerschlag, or the iron cinder, driven off from the blooms by the
tilting hammer, has been used instead of lime in the reduction of this
mercurial ore, whereby sulphurous acid and sulphuret of iron are formed.

The annual production of the Bavarian Rhine provinces has been estimated
at from 400 to 550 quintals; that of Almaden, in the year 1827, was
22,000 quintals; and of Idria, at present, is not more than 1500
quintals.

All the plans hitherto prescribed for distilling the ore along with
quicklime, are remarkably rude. In that practised at Landsberg by
Obermoschel, there is a great waste of labour, in charging the numerous
small cucurbits; there is a great waste of fuel in the mode of heating
them; a great waste of mercury by the imperfect luting of the retorts to
the receivers, as well as the imperfect condensation of the mercurial
vapours; and probably a considerable loss by pilfering.

The modes practised at Almaden and Idria are, in the greatest degree,
barbarous; the ores being heated upon open arches, and the vapours
attempted to be condensed by enclosing them within brick or stone and
mortar walls, which can never be rendered either sufficiently tight or
cool.

To obviate all these inconveniences and sources of loss, the proper
chemical arrangements suited to the present improved state of the arts
ought to be adopted, by which labour, fuel, and mercury, might all be
economized to the utmost extent. The only apparatus fit to be employed
is a series of cast-iron cylinder retorts, somewhat like those employed
in the coal gas works, but with peculiarities suited to the condensation
of the mercurial vapours. Into each of these retorts, supposed to be at
least one foot square in area, and 7 feet long, 6 or 7 cwt. of a mixture
of the ground ore with the quicklime, may be easily introduced, from a
measured heap, by means of a shovel. The specific gravity of the
cinnabar being more than 6 times that of water, a cubic foot of it will
weigh more than 3-1/2 cwt.; but supposing the mixture of it with
quicklime (when the ore does not contain the calcareous matter itself)
to be only thrice the density of water, then four cubic feet might be
put into each of the above retorts, and still leave 1-1/2 cubic feet of
empty space for the expansion of volume which may take place in the
decomposition. The ore should certainly be ground to a moderately fine
powder, by stamps, iron cylinders, or an edge wheel, so that when mixed
with quicklime, the cinnabar may be brought into intimate contact with
its decomposer, otherwise much of it will be dissipated unproductively
in fumes, for it is extremely volatile.

_Figs._ 667, 668, 669. represent a cheap and powerful apparatus which I
contrived at the request of the German Mines Company of London, and
which is now mounted at Landsberg, near Obermoschel, in the Bavarian
Rhein-Kreis.

[Illustration: 667]

_Fig._ 667. is a section parallel to the front elevation of three arched
benches of retorts, of the size above specified. Each bench contains 3
retorts, of the form represented by _a a a_. I, is the single fire-place
or furnace, capable of giving adequate ignition by coal or wood, to the
three retorts. The retorts were built up in an excellent manner, by an
English mason perfectly acquainted with the best modes of erecting
coal-gas retorts, who was sent over on purpose. The path of the flame
and smoke is precisely similar to that represented in _fig._ 483, page
549, whereby the uppermost retort is immersed in a bath of uniformly
ignited air, while the currents reverberated from the top, play round
the two undermost retorts, in their way to the vent-flues beneath them.
The bottom of the uppermost retort is protected from the direct impulse
of the flame by fire-tiles. The dotted lines K K, show the paths of the
chimneys which rise at the back ends of the retorts.

[Illustration: 668 669]

In the section, _fig._ 668., _a_ is the body of the retort; its mouth at
the right hand end is shut, as usual, by a luted iron lid, secured with
a cross-bar and screw-bolts; its other end is prolonged by a sloping
pipe of cast iron, 4 inches in diameter, furnished with a nozzle hole at
L, closed with a screw plug. Through this hole a wire rammer may be
introduced, to ascertain that the tube is pervious, and to cleanse it
from the mercurial soot, when thought necessary. _c_, is a cross section
of the main condenser, shown in a longitudinal section at C C, _fig._
669. This pipe is 18 inches in diameter, and about 20 feet long. At _a
a_, &c., the back ends of the retorts are seen, with the slanting tubes
_b b_, &c., descending through orifices in the upper surface of the
condenser pipe, and dipping their ends just below the water-line _h i_.
_g_, is the cap of a water valve, which removes all risk from sudden
expansion or condensation. The condenser is placed within a rectangular
trough, made either of wood or stone, through which a sufficient stream
of water passes to keep it perfectly cool, and repress every trace of
mercurial vapour, and it is laid with a slight inclination from _i_ to
_h_, so that the condensed quicksilver may spontaneously flow along its
bottom, and pass through the vertical tube D into the locked up iron
chest, or magazine _e_. This tube D is from the beginning closed at
bottom, by immersion in a shallow iron cup, always filled with mercury.
_k_ is a graduated gauge rod, to indicate the progressive accumulation
of quicksilver in the chest, without being under the necessity of
unlocking it.

This air-tight apparatus was erected about a year ago, and has been
found to act perfectly well; I regret, however, that my professional
engagements at home have not hitherto permitted me to conduct its
operations personally for some days. The average samples of cinnabar ore
from Obermoschel are ten times poorer than those of Almaden. Were such
an apparatus as the above, with some slight modifications which have
lately occurred to me, mounted for the Spanish mines, I am confident
that their produce in quicksilver might be nearly doubled, with a vast
economy of fuel, labour, and human life. The whole cost of the 9 large
retorts, with their condensing apparatus, iron magazine, &c., was very
little more than _two hundred pounds_! As the retorts are kept in a
state of nearly uniform ignition, like those of the gas works, neither
they, nor the furnaces are liable to be injured in their joints by the
alternate contractions and expansions, which they would inevitably
suffer if allowed to cool; and being always ready heated to the proper
pitch for decomposing the mercurial ores, they are capable of working
off a charge, under skilful management, in the course of 3 hours. Thus,
in 24 hours, with a relay of labourers, 8 charges of at least 5 cwts. of
ore each, might be smelted = 2 tons, with 3 retorts, and 6 tons with 9
retorts; with a daily product from the rich ores of Almaden, or even
Idria, of from 12 cwts. to 20 cwts. Instead of 3 benches of 3 retorts
each, I would recommend 15 benches, containing 45 retorts, to be erected
for either the Almaden or Idria mines; which, while they would smelt all
their ores, could be got for a sum not much exceeding 1000_l._, an
outlay which they would reimburse within a month or two.

Quicksilver is a substance of paramount value to science. Its great
density and its regular rate of expansion and contraction by increase
and diminution of temperature, give it the preference over all liquids
for filling barometric and thermometric tubes. In chemistry it furnishes
the only means of collecting and manipulating, in the pneumatic trough,
such gaseous bodies as are condensable over water. To its aid, in this
respect, the modern advancement of chemical discovery is pre-eminently
due.

This metal alloyed with tin-foil forms the reflecting surface of looking
glasses, and by its ready solution of gold or silver, and subsequent
dissipation by a moderate heat, it becomes the great instrument of the
arts of gilding and silvering copper and brass. The same property makes
it so available in extracting these precious metals from their ores. The
anatomist applies it elegantly, to distend and display the minuter
vessels of the lymphatic system, and secretory systems, by injecting it
with a syringe through all their convolutions. It is the basis of many
very powerful medicines, at present probably too indiscriminately used,
to the great detriment of English society; for it is far more sparingly
prescribed by practitioners upon the continent of Europe, not otherwise
superior in skill or science to those of Great Britain.

The nitrate of mercury is employed for the _secrétage_ of rabbit and
hare-skins, that is, for communicating to the fur of these and other
quadrupeds the faculty of felting, which they do not naturally possess.
With this view the solution of that salt is applied to them lightly in
one direction with a sponge. A compound amalgam of zinc and tin is
probably the best exciter which can be applied to the cushions of
electrical machines. Mercury imported for home consumption in 1836,
286,808 lbs.; in 1837, 314,036 lbs.

The only mercurial compounds which are extensively used in the arts, are
fictitious cinnabar or VERMILLION, and corrosive sublimate.


MERCURY, BICHLORIDE OF; _Corrosive sublimate_; (_Deutochlorure de
mercure_, Fr.; _Aetzendes quecksilber sublimat_, Germ.) is made by
subliming a mixture of equal parts of persulphate of mercury, prepared
as above described, and sea-salt, in a stone-ware cucurbit. The
sublimate rises in vapour, and encrusts the globular glass capital with
a white mass of small prismatic needles. Its specific gravity is 5·14.
Its taste is acrid, stypto-metallic, and exceedingly unpleasant. It is
soluble in 20 parts of water, at the ordinary temperature, and in its
own weight of boiling water. It dissolves in 2-1/2 times its weight of
cold alcohol. It is a very deadly poison. Raw white of egg swallowed in
profusion, is the best antidote. A solution of corrosive sublimate has
been long employed for preserving soft anatomical preparations. By this
means the corpse of Colonel Morland was embalmed, in order to be brought
from the seat of war to Paris. His features remained unaltered, only his
skin was brown, and his body was so hard as to sound like a piece of
wood when struck with a hammer.

In the valuable work upon the dry rot, published by Mr. Knowles,
secretary of the committee of inspectors of the navy, in 1821, corrosive
sublimate is enumerated among the chemical substances which had been
prescribed for preventing the dry rot in timber; and it is well known
that Sir H. Davy had, several years before that date, used and
recommended to the Admiralty and Navy Board, corrosive sublimate as an
anti-dry rot application. It has been since extensively employed by a
joint-stock company for the same purpose, under the title of Kyan’s
patent.


MERCURY, PROTOCHLORIDE OF; _Calomel_; (_Protochlorure de mercure_, Fr.,
_Versüsstes quecksilber_, Germ.) This compound, so much used and abused
by medical practitioners, is commonly prepared by triturating four parts
of corrosive sublimate along with three parts of running quicksilver in
a marble mortar, till the metallic globules entirely disappear, with the
production of a black powder, which is to be put into a glass balloon,
and exposed to a subliming heat in a sand bath. The calomel, which rises
in vapour, and attaches itself in a crystalline crust to the upper
hemisphere of the balloon, is to be detached, reduced to a fine powder,
or levigated and elutriated. 200 lbs. of mercury yield 236 of calomel
and 272 of corrosive sublimate.

The following more economical process is that adopted at the
Apothecaries’ Hall, London. 140 pounds of concentrated sulphuric acid
are boiled in a cast iron pot upon 100 pounds of mercury, till a dry
persulphate is obtained. Of this salt, 124 pounds are triturated with 81
pounds of mercury, till the globules disappear, and till a protosulphate
be formed. This is to be intimately mixed with 68 pounds of sea-salt,
and the mixture, being put into a large stone-ware cucurbit, is to be
submitted to a subliming heat. See CALOMEL.

From 190 to 200 pounds of calomel rise in a crystalline cake, as in the
former process, into the capital; while sulphate of soda remains at the
bottom of the alembic. The calomel must be ground to an impalpable
powder, and elutriated. The vapours, instead of being condensed into a
cake within the top of the globe or in a capital, may be allowed to
diffuse themselves into a close vessel, containing water in a state of
ebullition, whereby the calomel is obtained at once in the form of a
washed impalpable powder. Calomel is tasteless and insoluble in water.
Its specific gravity is 7·176.

For the compound of mercury with fulminic acid, see FULMINATE.
_Periodide of mercury_ is a bright but fugitive red pigment. It is
easily prepared by dropping a solution of iodide of potassium into a
solution of corrosive sublimate, as long as any precipitation takes
place, decanting off the supernatant muriate of potash, washing and
drying the precipitate.


METALLURGY (_Erzkunde_, Germ.) is the art of extracting metals from
their ores. This art, which supplies industry with the instruments most
essential to its wants, is alike dependent upon the sciences of
chemistry and mechanics; upon the former, as directing the smelting
processes, best adapted to disentangle each metal from its mineralizer;
upon the latter, as furnishing the means of grinding the ores, and
separating the light stony parts from the rich metallic matter.

Notwithstanding the striking analogy which exists between common
chemical and metallurgic operations, since both are employed to insulate
certain bodies from others, there are essential differences which should
be carefully noted. In the first place, the quantity of materials being
always very great in metallurgy, requires corresponding adaptations of
apparatus, and often produces peculiar phenomena; in the second place,
the agents to be employed for treating great masses, must be selected
with a view to economy, as well as to chemical action. In analytical
chemistry, the main object being exactness of result, and purity of
product, little attention is bestowed upon the value of the reagents, on
account of the small quantity required for any particular process. But
in smelting metals upon the great scale, profit being the sole object,
cheap materials and easy operations alone are admissible.

The metallic ores as presented by nature, are almost always mixed with a
considerable number of foreign substances; and could not therefore be
advantageously submitted to metallurgic operations, till they are
purified and concentrated to a certain degree by various methods.

OF THE PREPARATION OF ORES FOR THE SMELTING HOUSE.

There are two kinds of _preparation_; the one termed mechanical, from
the means employed, and the results obtained, consists in processes for
breaking and grinding the ores, and for washing them so as to separate
the vein-stones, gangues, or other mixed earthy matters, in order to
insulate or concentrate the metallic parts.

Another kind of preparation, called chemical, has for its object to
separate, by means of fire, various volatile substances combined in the
ores, and which it is requisite to clear away, at least in a certain
degree, before trying to extract the metals they may contain.

Lastly, an indispensable operation in several circumstances, is to
discover, by simple and cheap methods, called _assays_, the quantity of
metal contained in the different species of ores to be treated.

This head of our subject, therefore, falls under three subdivisions:--

§ 1. The mechanical preparation of ores, including _picking_,
_stamping_, and different modes of washing.

§ 2. The chemical preparation, consisting especially in the roasting or
calcination of the ores.

§ 3. The assay of ores, comprehending the mechanical part: that is, by
washing; the chemical part, or assays by the _dry way_; and the assays
by the _moist way_.

_Section_ 1. _Of the mechanical preparation or dressing of ores._--I.
The first picking or sorting takes place in the interior, or
underground, workings, and consists in separating the fragments of
rocks, that apparently contain no metallic matter, from those that
contain more or less of it. The external aspect guides this separation;
as also the feeling of density in the hand.

The substances when turned out to the day, undergo another _sorting_,
with greater or less care, according to the value of the included metal.
This operation consists in breaking the lumps of ore with the hammer,
into fragments of greater or less size, usually as large as the fist,
whereby all the pieces may be picked out and thrown away that contain no
metal, and even such as contain too little to be smelted with advantage.
There is for the most part, a building erected near the output of the
mine, in which the breaking and picking of the ores are performed. In a
covered gallery, or under a shed, banks of earth are thrown up, and
divided into separate beds, on each of which a thick plate of cast iron
is laid. On this plate, elderly workmen, women, and children, break the
ores with hand hammers, then pick and sort them piece by piece. The
matters so treated, are usually separated into three parts; 1. the rock
or sterile gangue, which is thrown away; 2. the ore for the stamping
mill, which presents too intimate a mixture of rock and metallic
substance to admit of separation by breaking and picking; and 3. the
pure ore, or at least the very rich portion, called the _sorted mine_ or
the _fat ore_. On the sorting floors there remains much small rubbish,
which might form a fourth subdivision of ore, since it is treated in a
peculiar manner, by sifting, as will be presently mentioned.

The distribution of fragments more or less rich, in one class or
another, is relative to the value of the included metal, taking into
account the expenses necessary for its extraction. Thus in certain lead
mines, pieces of the gangues are thrown away, which judged by the eye
may contain 3 per cent. of galena, because it is known that the greater
portion of this would be lost in the washings required for separating
the 97 parts of the gangue, and that the remainder would not pay the
expenses.

II. The very simple operations of _picking_ are common to almost all
ores; but there are other operations requiring more skill, care, and
expense, which are employed in their final state of perfection only upon
ores of metals possessing a certain value, as those of lead, silver, &c.
We allude to the _washing_ of ores.

The most simple and economical washings are those that certain iron
ores, particularly the alluvial, are subjected to, as they are found
near the surface of the ground agglutinated in great or little pieces.
It is often useful to clean these pieces, in order to pick out the
earthy lumps, which would be altogether injurious in the furnaces.

This crude washing is performed sometimes by men stirring in the midst
of a stream of water, with iron rakes or shovels, the lumps of ore
placed in large chests, or basins of wood or iron.

In other situations, this washing is executed more economically by a
machine called a _buddle_ or dolly-tub by our miners. A trough of wood
or iron, with a concave bottom, is filled with the ore to be washed.
Within the tub or trough, arms or iron handles are moved round about,
being attached to the arbor of a hydraulic wheel. The trough is kept
always full of water, which as it is renewed carries off the earthy
matters, diffused through it by the motion of the machine, and the
friction among the pieces of the ore. When the washing is finished, a
door in one of the sides of the trough is opened, and the current
removes the ore into a more spacious basin, where it is subjected to a
kind of picking. It is frequently indeed passed through sieves in
different modes. See LEAD and TIN, for figures of _buddles_ and
_dollies_.

[Illustration: 670]

III. _Stamping._ Before describing the refined methods of washing the
more valuable ores of copper, silver, lead, &c., it is proper to point
out the means of reducing them into a powder of greater or less
fineness, by _stamping_, so called from the name _stamps_ of the pestles
employed for that purpose. Its usefulness is not restricted to preparing
the ores; for it is employed in almost every smelting house for pounding
clays, charcoal, scoriæ, &c. A stamping mill or pounding machine, _fig._
670., consists of several movable pillars of wood _l l l_, placed
vertically, and supported in this position between frames of carpentry K
K K. These pieces are each armed at their under end with a mass of iron
_m_. An arbor or axle _a a_, moved by water, and turning horizontally,
tosses up these wooden pestles, by means of wipers or cams, which lay
hold of the shoulders of the pestles at _l l l_. These are raised in
succession, and fall into an oblong trough below _m m_, scooped out in
the ground, having its bottom covered either with plates of iron or hard
stones. In this trough, beneath these pestles, the ore to be stamped is
allowed to fall from a hopper above, which is kept constantly full.

The trough is closed in at the sides by two partitions, and includes
three or four pestles; which the French miners call a battery. They are
so disposed that their ascent and descent take place at equal intervals
of time.

Usually a stamping machine is composed of several batteries (two, three,
or four), and the arrangement of the wipers on the arbor of the
hydraulic wheel is such that there is constantly a like number of
pestles lifted at a time; a circumstance important for maintaining the
uniform going of the machine.

The matters that are not to be exposed to subsequent washing are stamped
dry, that is without leading water into the trough; and the same thing
is sometimes done with the rich ores, whose lighter parts might
otherwise be lost.

Most usually, especially for ores of lead, silver, copper, &c., the
trough of the stamper is placed in the middle of a current of water, of
greater or less force; which, sweeping off the pounded substances,
deposits them at a greater or less distance onwards, in the order of the
size and richness of the grain; constituting a first washing, as they
escape from beneath the pestles.

In the dry stamping, the fineness of the powder depends on the weight of
the pestles, the height of their fall, and the period of their action
upon the ore; but in the stampers exposed to a stream of water, the
retention of the matters in the trough is longer or shorter, according
to the facility given for their escape. Sometimes these matters flow out
of the chest over its edges, and the height of the line they must
surmount has an influence on the size of the grain; at other times, the
water and the pounded matter which it carries off, are made to pass
through a grating, causing a kind of sifting at the same time. There
are, however, some differences in the results of these two methods.
Lastly, the quantity of water that traverses the trough, as well as its
velocity, has an influence on the discharge of the pounded matters, and
consequently on the products of the stampers.

The size of the particles of the pounded ore being different, according
to the variable hardness of the matters which compose them, suggests the
means of classing them, and distributing them nearly in the order of
their size and specific gravity, by making the water, as it escapes from
the stamping trough, circulate in a system of canals called a
_labyrinth_, where it deposits successively, in proportion as it loses
its velocity, the earthy and metallic matters it had floated along.
These metalliferous portions, especially when they have a great specific
gravity like galena, would be deposited in the first passages, were it
not that from their hardness being inferior to that of the _gangue_,
they are reduced to a much finer powder, or into thin plates, which seem
to adhere to both the watery and earthy particles; whence they have to
be sought for among the finest portions of the pulverised gangue, called
slime, _schlich_, or _schlamme_.

There are several methods of conducting the stamps; in reference to the
size of the grains wished to be obtained, and which is previously
determined agreeably to the nature of the ore, and of the gangue; its
richness, &c. The height of the slit that lets the pounded matters
escape, or the diameters of the holes in the grating, their distance,
the quantity of water flowing in, its velocity, &c., modify the result
of the stamping operation.

When it is requisite to obtain powder of an extreme fineness, as for
ores that are to be subjected to the process of amalgamation, they are
passed under millstones, as in common corn mills; and after grinding,
they are bolted so as to form a species of flour; or they are crushed
between rolls. See LEAD and TIN.

_Washing of ores._

IV. The ores pounded under the stamps are next exposed to very delicate
operations, both tedious and costly, which are called the _washings_.
Their purpose is to separate mechanically the earthy matters from the
metallic portion, which must therefore have a much higher specific
gravity; for otherwise, the washing would be impracticable.

The medium employed to diminish the difference of specific gravity, and
to move along the lightest matters, is water; which is made to flow with
greater or less velocity and abundance over the schlich or pasty mud
spread on a table of various inclination.

But as this operation always occasions, not only considerable expense,
but a certain loss of metal, it is right to calculate what is the degree
of richness below which washing is unprofitable; and on the other hand,
what is the degree of purification of the _schlich_ at which it is
proper to stop, because too much metal would be lost comparatively with
the expense of fusing a small additional quantity of gangue. There
cannot, indeed, be any fixed rule in this respect, since the elements of
these calculations vary for every work.

Before describing the different modes of washing, we must treat of the
sifting or riddling, whose purpose, like that of the labyrinth
succeeding the stamps, is to distribute and to separate the ores (which
have not passed through the water stamps) in the order of the coarseness
of grain. This operation is practised particularly upon the debris of
the mine, and the rubbish produced in breaking the ores. These
substances are put into a riddle, or species of round or square sieve,
whose bottom is formed of a grating instead of a plate of metal pierced
with holes. This riddle is plunged suddenly and repeatedly into a tub or
cistern filled with water. This liquid enters through the bottom, raises
up the mineral particles, separates them and keeps them suspended for an
instant, after which they fall down in nearly the order of their
specific gravities, and are thus classed with a certain degree of
regularity. The sieve is sometimes dipped by the immediate effort of the
washer; sometimes it is suspended to a swing which the workman moves; in
order that the riddling may be rightly done, the sieve should receive
but a single movement from below upwards; in this case the ore is
separated from the gangue, and if there be different specific gravities,
there is formed in the sieve as many distinct strata, which the workman
can easily take out with a _spatula_, throwing the upper part away when
it is too poor to be re-sifted. This operation by the hand-sieve, is
called _riddling in the tub_, or riddling by deposit.

We may observe, that during the sifting, the particles which can pass
across the holes of the bottom, fall into the tub and settle down there;
whence they are afterwards gathered out, and exposed to washing when
they are worth the trouble.

Sometimes, as at Poullaouen, the sieves are conical, and held by means
of two handles by a workman; and instead of receiving a single movement,
as in the preceding method, the sifter himself gives them a variety of
dexterous movements in succession. His object is to separate the poor
portions of the ore from the richer; in order to subject the former to
the stamp mill.

Among the siftings and washings which ores are made to undergo, we must
notice among the most useful and ingenious, those practised by _iron
gratings_, called on the Continent _grilles anglaises_, and the
_step-washings_ of Hungary, _laveries à gradins_. These methods of
freeing the ores from the pulverulent earthy matters, consist in placing
them, at their out-put from the mine, upon gratings, and bringing over
them a stream of water, which merely takes down through the bars the
small fragments, but carries off the pulverulent portions. The latter
are received in cisterns, where they are allowed to rest long enough to
settle to the bottom. The washing by steps is an extension of the
preceding plan. To form an idea, let us imagine a series of grates
placed successively at different levels, so that the water, arriving on
the highest, where the ore for washing lies, carries off a portion of
it, through this first grate upon a second closer in its bars, thence to
a third, &c., and finally into labyrinths or cisterns of deposition.

[Illustration: 671]

The _grilles anglaises_ are similar to the _sleeping tables_ used at
Idria. The system of these _en gradins_ is represented in _fig._ 671.
There are 5 such systems in the works at Idria, for the sorting of the
small morsels of quicksilver ore, intended for the stamping mill. These
fragments are but moderately rich in metal, and are picked up at random,
of various sizes, from that of the fist to a grain of dust.

These ores are placed in the chest _a_, below the level of which 7
grates are distributed, so that the fragments which pass through the
first _b_, proceed by an inclined conduit on to the second grate _c_,
and so in succession. (See the conduits _l_, _o_, _p_). In front, and on
a level with each of the grates _b_, _c_, _d_, &c., a child is stationed
on one of the floors, 1, 2, 3, to 7.

A current of water, which falls into the chest _a_, carries the
fragments of ore upon the grates. The pieces which remain upon the two
grates _b_ and _c_, are thrown on the adjoining table _v_, where they
undergo a sorting by hand; there the pieces are classified, 1. into
gangue to be thrown away; 2. into ore for the stamp mill; 3. into ore to
be sent directly to the furnace. The pieces which remain on each of the
succeeding grates, _d_, _e_, _f_, _g_, _h_, are deposited on those of
the floors 3 to 7, in front of each. Before every one of these shelves a
deposit-sieve is established, (see _t_, _u_,) and the workmen in charge
of it stand in one of the corresponding boxes, marked 8 to 12. The sieve
is represented only in front of the chest _h_, for the sake of
clearness.

Each of the workmen placed in 8, 9, 10, 11, 12, operates on the heap
before him; the upper layer of the deposit formed in his sieve, is sent
to the stamping house, and the inferior layer directly to the furnace.

As to the grains which, after traversing the five grates, have arrived
at the chest _x_, they are washed in the two chests _y_, which are
analogous to the German chests to be presently described. The upper
layer of what is deposited in _y_ is sent to the furnace; the rest is
treated anew on three tables of percussion, similar to the English
brake-sieves, also to be presently described.

After several successive manipulations on these tables, an upper stratum
of _schlich_ is obtained fit for the furnace; an intermediate stratum,
which is washed anew by the same process; and an inferior stratum, that
is sent to the system of stamps, _fig._ 672.

[Illustration: 672]

This figure represents the general ground plan of a stamping and washing
mill. The stamps F are composed of two batteries similar to _fig._ 670.
The ore passes in succession under three pestles of cast iron, each of
which is heavier the nearer it is to the sieve through which the _sand_
or pounded matter escapes.

In the upper part of the figure we see issuing from the stamps, two
conduits destined to receive the water and the metalliferous sand with
which it is loaded. The first, marked F, S, _w_, is used only when a
certain quality of ore is _stamped_, richer in metal than is usually
treated by means of the second conduit, the first being closed. The
second conduit, or that employed for ordinary manipulation when the
other is shut, is indicated by F, 0·7, B; then by 0·58 and 0·29. These
numbers express the depth of the corresponding portions of this conduit.
From F to B, the conduit or water-course is divided into three portions
much shallower, called the _rich conduit_, the _middle conduit_, and the
_inferior_. Beyond the basin B, the conduit takes the name of labyrinth.
There the muddy sediments of ore are deposited; being the finer the
further they are from the stamps F. Darts indicate the direction of the
stream in the labyrinth. On the _German chests_, placed at 3, the sand
derived from the rich and middle conduits is treated, in order to obtain
three distinct qualities of _schlich_, as already mentioned. P is a
cloth-covered table, for treating the deposit of the German chests at 3.
M N are two sweep tables (_à balai_), for treating the ore collected in
the lower conduit, which precedes the midmost of the three German
chests. Upon the three similar tables R T V, are treated in like manner
the muddy deposits of the labyrinth, which forms suite to three parallel
German chests situated at 3, not shown for want of room in the figure,
but connected in three rectangular zigzags with each other, as well as
by a transverse branch to the points 0·7 and P. At the upper part of
these five sweep tables, the materials which are to undergo washing are
agitated in two boxes O O, by small paddle-wheels.

We shall now describe the _percussion-tables_ used in the Hartz, for
treating the sand of ore obtained from the conduits represented above.

[Illustration: 673 674 675]

_Figs._ 673, 674. and 675. exhibit a plan, a vertical section, and
elevation, of one of these tables, taken in the direction of its length.
The _arbor_ or great shaft in prolongation from the stamps mill, is
shown in section perpendicularly to its axis, at A. The _cams_ or wipers
are shown round its circumference, one of them having just acted on _n_.

These cams, by the revolution of the arbor, cause the alternating
movements of a horizontal bar of wood _o_, _u_, which strikes at the
point _u_ against a table _d_, _b_, _c_, _u_. This table is suspended by
two chains _t_, at its superior end, and by two rods at its lower end.
After having been pushed by the piece _o_, _u_, it rebounds to strike
against a block or bracket B. A lever _p_, _q_, serves to adjust the
inclination of the movable table, the pivots _q_ being points of
suspension.

The ore-sand to be washed, is placed in the chest _a_, into which a
current of water runs. The ore floated onwards by the water, is carried
through a sieve on a sloping small table _x_, under which is concealed
the higher end of the movable table _d_, _b_, _c_, _u_; and it thence
falls on this table, diffusing itself uniformly over its surface. The
particles deposited on this table form an oblong _talus_ (slope) upon
it; the successive percussions that it receives, determine the weightier
matters, and consequently those richest in metal, to accumulate towards
its upper end at _u_. Now the workman by means of the lever _p_, raises
the lower end _d_ a little in order to preserve the same degree of
inclination to the surface on which the deposit is strewed. According as
the substances are swept along by the water, he is careful to remove
them from the middle of the table towards the top, by means of a wooden
roller. With this intent, he walks on the table _d b c u_, where the
sandy sediment has sufficient consistence to bear him. When the table is
abundantly charged with the washed ore, the deposit is divided into
three bands or segments _d b_, _b c_, _c u_. Each of these bands is
removed separately and thrown into the particular heap assigned to it.
Every one of the heaps thus formed becomes afterwards the object of a
separate manipulation on a percussion table, but always according to the
same procedure. It is sufficient in general to pass twice over this
table the matters contained in the heap, proceeding from the superior
band _c u_, in order to obtain a pure _schlich_; but the heap preceding
from the intermediate belt _b c_, requires always a greater number of
manipulations, and the lower band _d b_ still more. These successive
manipulations are so associated that eventually each heap furnishes pure
_schlich_, which is obtained from the superior band _c u_. As to the
lightest particles which the water sweeps away beyond the lower end of
the percussion table, they fall into conduits; whence they are lifted to
undergo a new manipulation.

[Illustration: 676]

_Fig._ 676. is a profile of a plan which has been advantageously
substituted, in the Hartz, for that part of the preceding apparatus
which causes the jolt of the piece _o u_ against the table _d b c u_. By
means of this plan, it is easy to vary, according to the circumstances
of a manipulation always delicate, the force of percussion which a bar
_x y_, ought to communicate by its extremity _y_. With this view, a
slender piece of wood _u_ is made to slide in an upright piece, _v x_,
adjusted upon an axis at _v_. To the piece _u_ a rod of iron is
connected, by means of a hinge _z_; this rod is capable of entering more
or less into a case or sheath in the middle of the piece _v x_, and of
being stopped at the proper point, by a thumb-screw which presses
against this piece. If it be wished to increase the force of percussion,
we must lower the point _z_; if to diminish it, we must raise it. In the
first case, the extremity of the piece _u_, advances so much further
under the cam of the driving shaft _t_; in the second, it goes so much
less forwards; whereby the adjustment is produced.

[Illustration: 677 678]

_Figs._ 677. and 678. represent a complete system of _sleeping tables_,
_tables dormantes_; such as are mounted in Idria. _Fig._ 678. is the
plan, and _fig._ 677. a vertical section. The mercurial ores, reduced to
a sand by stamps like those of _fig._ 672., pass into a series of
conduits _a a_, _b b_, _c c_, which form three successive floors below
the level of the floor of the works. The sand taken out of these
conduits is thrown into the cells _q_; whence they are transferred into
the trough _e_, and water is run upon them by turning two stopcocks for
each trough. The sand thus diffused upon each table, runs off with the
water by a groove _f_, comes upon a sieve _h_, spreads itself upon the
board _g_, and thence falls into the slanting chest, or sleeping table
_i k_. The under surface _k_ of this chest is pierced with holes, which
may be stopped at pleasure with wooden plugs. There is a conduit _m_, at
the lower end of each table, to catch the light particles carried off by
the water out of the chest _i k_, through the holes properly opened,
while the denser parts are deposited upon the bottom of this chest. A
general conduit _n_ passes across at the foot of all the chests _i k_;
it receives the refuse of the washing operations.

[Illustration: 679]

_Fig._ 679. is a set of stamping and washing works for the ores of
argentiferous galena, as mounted at _Bockwiese_, in the district of
Zellerfeldt, in the Hartz.

A is the stamp mill and its subsidiary parts; among which are _a_, the
driving or main shaft; _b_, the overshot water-wheel; _c c_, six strong
rings or hoops of cast iron, for receiving each a cam or tappet; _g_,
the brake of the machine; _k_, _k_, _k_, the three standards of the
stamps; _l l_, &c. six pestles of pine wood, shod with lumps of cast
iron. There are two chests, out of which the ore to be ground falls
spontaneously into the two troughs of the stamps. Of late years,
however, the ore is mostly supplied by hand; the watercourse terminates
a short distance above the middle of the wheel _b_. There is a stream of
water for the service of the stamps, and conduits proceeding from it, to
lead the water into the two stamp troughs; the conduit of discharge is
common to the two batteries or sets of stamps through which the water
carries off the sand or stamped ore. There is a movable table of
separation, mounted with two sieves. The sands pass immediately into the
conduit placed upon a level with the floor, and separated into two
compartments, the first of which empties its water into the second.
There are two boards of separation, or tables, laid upon the ground,
with a very slight slope of only 15 inches from their top to their
bottom. Each of these boards is divided into four cases with edges; the
whole being arranged so that it is possible, by means of a flood-gate or
sluice, to cause the superfluous water of the case to pass into the
following ones. Thus the work can go on without interruption, and
alternately upon the two boards. There are winding canals in the
labyrinth, N, N, N, in which are deposited the particles carried along
by the water which has passed upon the boards. The depth of these canals
gradually increases from 12 to 20 inches, to give a suitable descent for
maintaining the water-flow. At D, two percussion tables are placed. F G
are two German chests. H J are two percussion tables, which are driven
by the cams _z z_, fixed upon the main shaft _x y_. K K´ are two sloping
sweep tables (_à balai_).

The _German chests_ are rectangular, being about 3 yards long, half a
yard broad, with edges half a yard high; and their inclination is such
that the lower end is about 15 inches beneath the level of the upper. At
their upper end, usually called the bolster, a kind of trough or box,
without any edge at the side next the chest, is placed, containing the
ore to be washed. The water is allowed to fall upon the bolster in a
thin sheet.

The _sleeping tables_ have upright edges; they are from 4 to 5 yards
long, nearly 2 yards wide, and have fully a yard of inclination.

The preceding tables are sometimes covered with cloth, particularly in
treating ores that contain gold, on a supposition that the woollen or
linen fibres would retain more surely the metallic particles; but this
method appears on trial to merit no confidence, for it produces a very
impure _schlich_.

[Illustration: 680]

_Fig._ 680. is a swing-sieve employed in the Hartz, for sifting the
small fragments of the ore of argentiferous lead. Such an apparatus is
usually set up in the outside of a stamp, and washing mill; its place
being denoted by the letter A, _fig._ 672. The two movable chests or
boxes A B, of the sieve, are connected together, at their lower ends,
with an upright rod, which terminates at one of the arms of a small
balance beam, mounted between the driving shaft of the stamps and the
sieve, perpendicularly to the length of both. The opposite arm of this
beam carries another upright rod, which ears (cams or _mentonnets_),
placed on purpose upon the driving shaft, may push down. During this
movement the two lower ends A, B, are raised; and when the peg-cam of
the shaft quits the rod which it had depressed, the swing chests fall by
their own weight. Thus they are made to vibrate alternately upon their
axes. The small ore is put into the upper part of the chest A, over
which a stream of water falls from an adjoining conduit. The fragments
which cannot pass through a cast-iron grid in the bottom of that chest,
are sorted by hand upon a table in front of A, and they are classed by
the workman, either among the ores to be stamped, whether dry or wet, or
among the rubbish to be thrown away, or among the copper ores to be
smelted by themselves. As to the small particles which fall through the
grid upon the chest B, supplied also with a stream of water, they
descend successively upon two other brass wire sieves, and also through
the iron wire _r_, in the bottom of B.

In certain mines of the Hartz, tables called _à balais_, or _sweeping
tables_, are employed. The whole of the process consists in letting
flow, over the sloping table, in successive currents, water charged with
the ore, which is deposited at a less or greater distance, as also pure
water for the purpose of washing the deposited ore, afterwards carried
off by means of this sweeping operation.

At the upper end of these _sweep-tables_, the matters for washing are
agitated in a chest, by a small wheel with vanes, or flap-boards. The
conduit of the muddy waters opens above a little table or shelf; the
conduit of pure water, which adjoins the preceding, opens below it. At
the lower part of each of these tables, there is a transverse slit,
covered by a small door with hinges, opening outwardly, by falling back
towards the foot of the table. The water spreading over the table, may
at pleasure be let into this slit, by raising a bit of leather which is
nailed to the table, so as to cover the small door when it is in the
shut position; but when this is opened, the piece of leather then hangs
down into it. Otherwise the water may be allowed to pass freely above
the leather, when the door is shut. The same thing may be done with a
similar opening placed above the conduit. By means of these two slits,
two distinct qualities of _schlich_ may be obtained, which are deposited
into two distinct conduits or canals. The refuse of the operation is
turned into another conduit, and afterwards into ulterior reservoirs,
whence it is lifted out to undergo a new washing.

In the percussion tables, the water for washing the ores is sometimes
spread in slender streamlets, sometimes in a full body, so as to let two
cubic feet escape per minute. The number of shocks communicated per
minute, varies from 15 to 36; and the table may be pushed out of its
settled position at one time, three quarters of an inch, at another
nearly 8 inches. The coarse ore-sand requires in general less water, and
less slope of table, than the fine and pasty sand.

The _mechanical_ operations which ores undergo, take place commonly at
their out-put from the mine, and without any intermediate operation.
Sometimes, however, the hardness of certain _gangues_ (vein-stones), and
of certain iron-ores, is diminished by subjecting them to calcination
previously to the breaking and stamping processes.

When it is intended to wash certain ores, an operation founded on the
difference of their specific gravities, it may happen that by slightly
changing the chemical state of the substances that compose the ore, the
earthy parts may become more easily separable, as also the other foreign
matters. With this view, the ores of tin are subjected to a roasting,
which by separating the arsenic, and oxidizing the copper which are
intermixed, furnishes the means of obtaining, by the subsequent washing,
an oxide of tin much purer than could be otherwise procured. In general,
however, these are rare cases; so that the washing almost always
immediately succeeds the picking and stamping; and the roasting comes
next, when it needs to be employed.

The operation of roasting is in general executed by various processes,
relatively to the nature of the ores, the quality of the fuel, and to
the object in view. The greatest economy ought to be studied in the
fuel, as well as the labour; two most important circumstances, on
account of the great masses operated upon.

Three principal methods may be distinguished; 1. the roasting in a heap
in the open air, the most simple of the whole; 2. the roasting executed
between little walls, and which may be called case-roasting
(_rost-stadeln_, in German); and 3. roasting in furnaces.

We may remark, as to the description about to be given of these
different processes, that in the first two, the fuel is always in
immediate contact with the ore to be roasted, whilst in furnaces, this
contact may or may not take place.

1. The roasting in the open air, and in heaps more or less considerable,
is practised upon iron ores, and such as are pyritous or bituminous. The
operation consists in general in spreading over a plane area, often
bottomed with beaten clay, billets of wood arranged like the bars of a
gridiron, and sometimes laid crosswise over one another, so as to form a
uniform flat bed. Sometimes wood charcoal is scattered in, so as to fill
up the interstices, and to prevent the ore from falling between the
other pieces of the fuel. Coal is also employed in moderately small
lumps; and even occasionally, turf. The ore either simply broken into
pieces, or even sometimes under the form of _schlich_, is piled up over
the fuel; most usually alternate beds of fuel and ore are formed.

The fire, kindled in general at the lower part, but sometimes, however,
at the middle chimney, spreads from spot to spot, putting the operation
in train. The combustion must be so conducted as to be slow and
suffocated, to prolong the ustulation, and let the whole mass be equably
penetrated with heat. The means employed to direct the fire, are to
cover outwardly with earth the portions where too much activity is
displayed, and to pierce with holes or to give air to those where it is
imperfectly developed. Rains, winds, variable seasons, and especially
good primary arrangements of a calcination, have much influence on this
process, which requires, besides, an almost incessant inspection at the
beginning.

Nothing in general can be said as to the consumption of fuel, because it
varies with its quality, as well as with the ores and the purpose in
view. But it may be laid down as a good rule, to employ no more fuel
than is strictly necessary for the kind of calcination in hand, and for
supporting the combustion; for an excess of fuel would produce, besides
an expense uselessly incurred, the inconvenience, at times very serious,
of such a heat as may melt or vitrify the ores; a result entirely the
reverse of a well-conducted ustulation.

[Illustration: 681 682 683]

_Figs._ 681, 682, 683. represent the roasting in mounds, as practised
near Goslar in the Hartz, and at Chessy in the department of the Rhone.
_Fig._ 681. is a vertical section in the line _h c_ of _figs._ 682. and
683. In _fig._ 682. there is shown in plan, only a little more than one
half of the quadrangular truncated pyramid, which constitutes the heap.
_Fig._ 683. shows a little more than one fourth of a bed of wood,
arranged at the bottom of the pyramid, as shown by _a a_, _fig._ 681.,
and _c g h_, _fig._ 683. C is a wooden chimney, formed within the heap
of ore, at whose bottom _c_ there is a little parcel of charcoal, _d d_
are large lumps of ore distributed upon the wooden pile _a a_; _e e_ are
smaller fragments, to cover the larger; _f f_ is rubbish and clay laid
smoothly in a slope over the whole. _g_, _fig._ 683., a passage for air
left under the bed of billets; of which there is a similar one in each
of the four sides of the base _a a_, so that two principal currents of
air cross under the upright axis C _c_, of the truncated pyramid
indicated in _fig._ 681.

The kindling is thrown in by the chimney C. The charcoal _c_, and the
wood _a a_, take fire; the sulphureous ores _d e f_ are heated to such a
high temperature as to vaporize the sulphur. In the Lower Hartz, a heap
of this kind continues roasting during four months.

2. The second method. The difficulty of managing the fire in the
roasting of substances containing little sulphur, with the greater
difficulty of arranging and supporting in their place the _schlichs_ to
be roasted, and last of all, the necessity of giving successive fires to
the same ores, or to inconsiderable quantities at a time, have led to
the contrivance of surrounding the area on which the roasting takes
place with three little walls, or with four, leaving a door in the one
in front. This is what is called a _walled area_, and sometimes,
improperly enough, a roasting furnace. Inside of these little walls,
about 3 feet high, there are often vertical conduits or chimneys made to
correspond with an opening on the ground level, in order to excite a
draught of air in the adjacent parts. When the roasting is once set
agoing, these chimneys can be opened or shut at their upper ends,
according to the necessities of the process.

Several such furnaces are usually erected in connexion with each other
by their lateral walls, and all terminated by a common wall, which forms
their posterior part; sometimes they are covered with a shed supported
partly by the back wall, built sufficiently high for this purpose. These
dispositions are suitable for the roasting of _schlichs_, and in general
of all matters which are to have several fires; a circumstance often
indispensable to a due separation of the sulphur, arsenic, &c.

3. The furnaces employed for roasting the ores and the _mattes_ differ
much, according to the nature of the ores, and the size of the lumps.
We shall content ourselves with referring to the principal forms.

When iron ores are to be roasted, which require but a simple calcination
to disengage the combined water and carbonic acid, egg-shaped furnaces,
similar to those in which limestone is burned in contact with fuel, may
be conveniently employed; and they present the advantage of an operation
which is continuous with a never-cooling apparatus. The analogy in the
effects to be produced is so perfect, that the same furnace may be used
for either object. Greater dimensions may, however, be given to those
destined for the calcination of iron ores. But it must be remembered
that this process is applicable only to ores broken into lumps, and not
to ores in grains or powder.

It has been attempted to employ the same method a little modified, for
the roasting of ores of sulphuret of copper and pyrites, with the view
of extracting a part of the sulphur. More or less success has ensued,
but without ever surmounting all the obstacles arising from the great
fusibility of the sulphuret of iron. For sometimes it runs into one
mass, or at least into lumps agglutinated together in certain parts of
the furnace, and the operation is either stopped altogether, or becomes
more or less languid; the air not being able to penetrate into all the
parts, the roasting becomes consequently imperfect. This inconvenience
is even more serious than might at first sight appear; for, as the
ill-roasted ores now contain too little sulphur to support their
combustion, and as they sometimes fall into small fragments in the
cooling, they cannot be passed again through the same furnace, and it
becomes necessary to finish the roasting in a reverberatory hearth,
which is much more expensive.

In the Pyrenees, the roasting of iron ores is executed in a circular
furnace, so disposed that the fuel is contained and burned in a kind of
interior oven, above which lie the pieces of ore to be calcined.
Sometimes the vault of this oven which sustains the ore, is formed of
bricks, leaving between them openings for the passage of the flame and
the smoke, and the apparatus then resembles certain pottery kilns; at
other times the vault is formed of large lumps of ore, carefully
arranged as to the intervals requisite to be left for draught over the
arch. The broken ore is then distributed above this arch, care being
taken to place the larger pieces undermost. This process is simple in
the construction of the furnace, and economical, as branches of trees,
without value in the forests, may be employed in the roasting. See
_Lime-kiln_ figures.

In some other countries, the ores are roasted in furnaces very like
those in which porcelain is baked; that is to say, the fuel is placed
exteriorly to the body of the furnace in a kind of brick shafts, and the
flame traverses the broken ore with which the furnace is filled. In such
an apparatus the calcination is continuous.

When it is proposed to extract the sulphur from the iron pyrites, or
from pyritous minerals, different furnaces may be employed, among which
that used in Hungary deserves notice. It is a rectangular parallelopiped
of four walls, each of them being perforated with holes and vertical
conduits which lead into chambers of condensation, where the sulphur is
collected. The ore placed between the four walls on billets of wood
arranged as in _figs._ 681, 682, 683., for the great roastings in the
open air, is calcined with the disengagement of much sulphur, which
finds more facility in escaping by the lateral conduits in the walls,
than up through the whole mass, or across the upper surface covered over
with earth; whence it passes into the chambers of condensation. In this
way upwards of a thousand tons of pyrites may be roasted at once, and a
large quantity of sulphur obtained. See COPPER.

[Illustration: 684 685]

_Roasting of Pyrites._--_Figs._ 684, 685. represent a furnace which has
been long employed at Fahlun in Sweden, and several other parts of that
kingdom, for roasting iron pyrites in order to obtain sulphur. This
apparatus was constructed by the celebrated Gahn. _Fig._ 684. is a
vertical section, in the line _k d n o_ of _fig._ 685., which is a plan
of the furnace; the top being supposed to be taken off. In both figures
the conduit may be imagined to to be broken off at _e_; its entire
length in a straight line is 43 feet beyond the dotted line _e n_,
before the bend, which is an extension of this conduit. Upon the slope
_a b_ of a hillock _a b c_, lumps _r_ of iron pyrites are piled upon the
pieces of wood _i i_ for roasting. A conduit _d f e_ forms the
continuation of the space denoted by _r_, which is covered by stone
slabs so far as _f_; and from this point to the chamber _h_ it is
constructed in boards. At the beginning of this conduit, there is a
recipient _g_. The chamber _h_ is divided into five chambers by
horizontal partitions, which permit the circulation of the vapours from
one compartment to another. The ores _r_ being distributed upon the
billets of wood _i i_, whenever these are fairly kindled, they are
covered with small ore, and then with rammed earth _l l_. Towards the
point _m_, for a space of a foot square, the ores are covered with
movable stone slabs, by means of which the fire may be regulated, by the
displacement of one or more, as may be deemed necessary. The liquid
sulphur runs into the recipient _g_, whence it is laded out from time to
time. The sublimed sulphur passes into the conduit _f e_ and the chamber
_h_, from which it is taken out, and washed with water, to free it from
sulphuric acid with which it is somewhat impregnated; it is afterwards
distilled in cast-iron retorts. The residuum of the pyrites is turned to
account in Sweden, for the preparation of a common red colour much used
as a pigment for wooden buildings.

The reverberatory furnace affords one of the best means of ustulation,
where it is requisite to employ the simultaneous action of heat and
atmospherical air to destroy certain combinations, and to decompose the
sulphurets, arseniurets, &c. It is likewise evident that the facility
thus offered of stirring the matters spread out on the sole, in order to
renew the surfaces, of observing their appearances, of augmenting or
diminishing the degree of heat, &c., promise a success much surer, a
roasting far better executed, than by any other process. It is known,
besides, that flame mingled with much undecomposed air issuing from the
furnace, is highly oxidizing, and is very fit for burning away the
sulphur, and oxidizing the metals. Finally, this is almost the only
method of rightly roasting ores which are in a very fine powder. If it
be not employed constantly and for every kind of ore, it is just because
more economy is found in practising calcination in heaps, or on areas
enclosed by walls; besides, in certain mines, a very great number of
these furnaces, and many workmen, would be required to roast the
considerable body of ores that must be daily smelted. Hence there would
result from the construction of such apparatus and its maintenance a
very notable outlay, which is saved in the other processes.

But in every case where it is desired to have a very perfect roasting,
as for blende from which zinc is to be extracted, for sulphuret of
antimony, &c., or even for ores reduced to a very fine powder, and
destined for amalgamation, it is proper to perform the operation in a
reverberatory furnace. When very fusible sulphurous ores are treated,
the workman charged with the calcination must employ much care and
experience, chiefly in the management of the fire. It will sometimes,
indeed, happen, that the ore partially fuses; when it becomes necessary
to withdraw the materials from the furnace, to let them cool and grind
them anew, in order to recommence the operation. The construction of
these furnaces demands no other attention than to give to the sole or
laboratory the suitable size, and so to proportion to this the grate and
the chimney that the heating may be effected with the greatest economy.

The reverberatory furnace is always employed to roast the ores of
precious metals, and especially those for amalgamation; as the latter
often contain arsenic, antimony, and other volatile substances, they
must be disposed of in a peculiar manner.

The sole, usually very spacious, is divided into two parts, of which the
one farthest off from the furnace is a little higher than the other.
Above the vault there is a space or chamber in which the ore is
deposited, and which communicates with the laboratory by a vertical
passage; which serves to allow the ore to be pushed down, when it is
dried and a little heated. The flame and the smoke which escape from the
sole or laboratory pass into condensing chambers, before entering into
the chimney of draught, so as to deposit in them the oxide of arsenic
and other substances. When the ore on the part of the sole farthest from
the grate has suffered so much heat as to begin to be roasted, has
became less fusible, and when the roasting of that in the nearer part of
the sole is completed, the former is raked towards the fire-bridge, and
its ustulation is finished by stirring it over frequently with a paddle,
skilfully worked, through one of the doors left in the side for this
purpose. The operation is considered to be finished when the vapours and
the smell have almost wholly ceased; its duration depending obviously on
the nature of the ores.

When this furnace is employed to roast very arsenical ores, as the tin
ores of Schlackenwald in Bohemia, and at Ehrenfriedersdorf in Saxony,
the arsenical pyrites of Geyer (in Saxony), &c., the chambers of
condensation for the arsenious acid are much more extensive than in the
furnaces commonly used for roasting galena, copper, or even silver ores.

[Illustration: 686 687 688]

_Figs._ 686, 687, 688. represent a reverberatory furnace employed in the
smelting works of Lautenthal, in the Hartz, for roasting the schlichs of
lead ores, which contain much blende or sulphuret of zinc. In _fig._
686. we see that the two parts A B, B C, are absolutely like, the two
furnaces being built in one body of brickwork. _Fig._ 687. is the plan
of the furnace B C, taken at the level E F of _fig._ 686. _Fig._ 688. is
a vertical section of the similar furnace A B, taken in the prolongation
of the line G H in _fig._ 687.

_a_ is the fire-place of the furnace, its grate and ash-pit. _b_ is the
conduit of vaporization, which communicates with the chambers _c_; _c_,
chambers into which the vaporized substances are deposited; _d_, chimney
for the escape of the smoke of the fire-place _a_, after it has gone
through the space _b c c_; _e´_, is the charging door, with a hook
hanging in front to rest the long iron rake upon, with which the
materials are turned over; _f_, chamber containing a quantity of schlich
destined for roasting; this chamber communicates with the vaulted
corridor (gallery) D, seen in _fig._ 686.; _g_, orifice through which
the schlich is thrown into the furnace; _h_, area or hearth of the
reverberatory furnace, of which the roof is certainly much too high;
_i_, channels for the escape of the watery vapours; _k l_, front arcade,
between which and the furnace, properly speaking, are the two orifices
of the conduits, which terminate at the channels _m_, _m´_. _m_ is the
channel for carrying towards the chimney _d_, the vapours which escape
by the door _e´_. _n_ is a walled-up door, which is opened from time to
time, to take out of the chambers _c_, _c_, the substances that may be
deposited in them.

At the smelting works of Lautenthal, in such a roasting furnace, from 6
to 9 quintals (cwts.) of schlich are treated at a time, and it is
stirred frequently with an iron rake upon the altar _h_. The period of
this operation is from 6 to 12 hours, according as the schlich may be
more or less dry, more or less rich in lead, or more or less charged
with blende. When the latter substance is abundant, the process requires
12 hours, with about 60 cubic feet of cleft billets for fuel.

In such furnaces are roasted the cobalt ores of Schneeberg in Saxony,
the tin ores of Schlackenwald in Bohemia, of Ehrenfriedersdorf in
Saxony, and elsewhere; as also the arsenical pyrites at Geyer in Saxony.
But there are poison towers and extensive condensing chambers attached
in the latter case. See ARSENIC.

_Figs._ 689, 690, 691. represent the reverberatory furnace generally
employed in the Hartz, in the district of Mansfeldt, Saxony, Hungary,
&c., for the treatment of black copper, and for refining rose copper
upon the great scale. An analogous furnace is used at Andreasberg for
the liquefaction or purification of the mattes, and for workable lead
when it is much loaded with arsenic.

[Illustration: 689 690 691]

_Fig._ 689. presents the elevation of the furnace parallel to the line I
K, of the plan _fig._ 690.; which plan is taken at the level of the
tuyère _n_, of _fig._ 691.; _fig._ 691. is a vertical section in the
line L M, _fig._ 690. _k_ represents one of two basins of reception,
brasqued with clay and charcoal; _n_, _n_, two tuyères, through which
enters the blast of two pairs of bellows, like those shown at
Cupellation of SILVER; _q_, door by which the matter to be melted is
laid upon the sole of the furnace; _v_, _v_, two points where the sole
is perforated, when necessary to run off the melted matter into either
of the basins _h_; _x_, door through which the slags or cinders floating
upon the surface of the melted metal are raked out; _y_, door of the
fire-place. The fuel is laid upon a grate above an ash-pit, and below
the arch of a reverberatory which is contiguous to the dome or cap of
the furnace properly so called. In the section, _fig._ 691., the
following parts may be noted: 1, 2, 3, mason-work of the foundation; 4,
vapour channels or conduits, for the escape of the humidity; 5, bed of
clay; 6, brasque composed of clay and charcoal, which forms the
concavity of the hearth.

[Illustration: 692 693 694]

_Figs._ 692, 693, 694., show the furnace employed for liquation in one
of the principal smelting works of the Hartz. _Fig._ 694. exhibits the
working area charged with the liquation cakes and charcoal, supported by
sheets of wrought iron; being an image of the process in action. _Fig._
693. is the plan, in the line F, G, of _fig._ 692.

A liquation cake is composed of--

Black copper holding at least 5 or 6 _loths_ (2-1/2 or 3 oz.) of silver
per cwt., and weighing 90 to 96 lbs.

Lead obtained from litharge, 2 cwts. Litharge, 1/2 cwt.

From 30 to 32 cakes are successively worked in one operation, which
lasts about 5 hours; the furnace is brought into action, as usual, with
the aid of slags; then a little litharge is added; when the lead begins
to flow, the copper is introduced, and when the copper flows, lead is
added, so that the mixture of the metals may be effected in the best way
possible.

From 8 to 16 of these cakes (_pains_) are usually placed in the
liquation furnace, _figs._ 692, 693, 694. The operation lasts 3 or 4
hours, in which time about 1-1/2 quintals of charcoal are consumed. The
cakes are covered with burning charcoal, supported, as I have said, by
the iron plates. The workable lead obtained flows off towards the basin
in front of the furnace; whence it is laded out into moulds set
alongside. See _fig._ 693. If the lead thus obtained be not sufficiently
rich in silver to be worth cupellation, it is employed to form new
liquation cakes. When it contains from 5 to 6 loths of silver per cwt.,
it is submitted to cupellation in the said smelting works. See SILVER.

[Illustration: 695 696 697]

The _trompe_, or water-blowing engine, _figs._ 695, 696, 697. _Fig._
695. is the elevation; _fig._ 696. is a vertical section, made at right
angles to the elevation. The machine is formed of two cylindrical pipes,
the bodies of the _trompe_ _b b_, set upright, called the funnels, which
terminate above in a water cistern _a_, and below in a close basin under
_c_, called the _tub_ or _drum_. The conical part _p_, of the funnel
has been called _etranguillon_, being _strangled_, as it were, in order
that the water discharged into the body of the trompe shall not fill the
pipe in falling, but be divided into many streamlets. Below this _narrow
part_, eight holes, _q q_, are perforated obliquely through the
substance of the trompe, called the vent-holes or nostrils, for
admitting the air, which the water carries with it in its descent. The
air afterwards parts from the water, by dashing upon a cast-iron slab,
placed in the _drum_ upon the pedestal _d_. An aperture _l_, at the
bottom of the drum, allows the water to flow away after its fall; but,
to prevent the air from escaping along with it, the water as it issues
is received in a chest _l m o n_, divided into two parts by a vertical
slide-plate between _m n_. By raising or lowering this plate, the water
may be maintained at any desired level within the drum, so as to give
the included air any determinate degree of pressure. The superfluous
water then flows off by the hole _o_.

The air-pipe _e f_, _fig._ 696., is fitted to the upper part of the
_drum_; it is divided, at the point _f_, into three tubes, of which the
principal one is destined for the furnace of cupellation, whilst the
other two _g g_, serve for different melting furnaces. Each of these
tubes ends in a leather pocket, and an iron nose-pipe _k_, adjusted in
the tuyère of the furnace. At Pesey, and in the whole of Savoy, a
floodgate is fitted into the upper cistern _a_, to regulate the
admission of water into the trome; but in Carniola, the funnel _p_ is
closed with a wooden plug, suspended to a cord, which goes round a
pulley mounted upon a horizontal axis, as shewn in _fig._ 697. By the
plug _a_ being raised more or less, merely the quantity of water
required for the operation is admitted. The plug is pierced lengthwise
with an oblique hole _c c_, in which the small tube _c_ is inserted,
with its top some way above the water level, through which air may be
admitted into the heart of the column descending into the trompe _p q_.

The ordinary height of the trompe apparatus is about 26 or 27 feet to
the upper level of the water cistern; its total length is 11 mètres (36
feet 6 inches), and its width 2 feet, to give room for the drums. It is
situated 10 mètres (33-1/3 feet) from the melting furnace. This is the
case at the smelting works of Jauerberg, in Upper Carniola.

OF THE ASSAY OF ORES.

Assays ought to occupy an important place in metallurgic instructions,
and there is reason to believe that the knowledge of assaying is not
sufficiently diffused, since its practice is so often neglected in
smelting houses. Not only ought the assays of the ores under treatment,
to be frequently repeated, because their nature is subject to vary; but
the different products of the furnaces should be subjected to reiterated
assays, at the several periods of the operations. When silver or gold
ores are in question, the docimastic operations, then indispensable,
exercise a salutary controul over the metallurgic processes, and afford
a clear indication of the quantities of precious metal which they ought
to produce.

By the title _Assays_, in a metallurgic point of view, is meant the
method of ascertaining for any substance whatever, not only the presence
and the nature of a metal, but its proportional quantity. Hence the
operations which do not lead to a precise determination of the metal in
question, are not to be arranged among the assays now under
consideration. Experiments made with the blow-pipe, although capable of
yielding most useful indications, are like the touchstone in regard to
gold, and do not constitute genuine assays.

Three kinds of assays may be practised in different circumstances, and
with more or less advantage upon different ores. 1. The mechanical
assay; 2. the assay by the dry way; 3. the assay by the humid way.

1. _Of mechanical assays._--These kinds of assays consist in the
separation of the substances mechanically mixed in the ores, and are
performed by a hand-washing, in a small trough of an oblong shape,
called a _sebilla_. After pulverizing with more or less pains the
matters to be assayed by this process, a determinate weight of them is
put into this wooden bowl with a little water; and by means of certain
movements and some precautions, to be learned only by practice, the
lightest substances may be pretty exactly separated, namely, the earthy
gangues from the denser matter or metallic particles, without losing any
sensible portion of them. Thus a _schlich_ of greater or less purity
will be obtained, which may afford the means of judging by its quality
of the richness of the assayed ores, and which may thereafter be
subjected to assays of another kind, whereby the whole metal may be
insulated.

Washing, as an assay, is practised on auriferous sands; on all ores from
the _stamps_, and even on _schlichs_ already washed upon the great
scale, to appreciate more nicely the degree of purity they have
acquired. The ores of tin in which the oxide is often disseminated in
much earthy gangue, are well adapted to this species of assay, because
the tin oxide is very dense. The mechanical assay may also be employed
in reference to the ores whose metallic portion presents an uniform
composition, provided it also possesses considerable specific gravity.
Thus the ores of sulphuret of lead (galena) being susceptible of
becoming almost pure sulphurets (within 1 or 2 _per cent._) by mere
washing skilfully conducted, the richness of that ore in pure galena,
and consequently in lead, may be at once concluded; since 120 of galena
contain 104 of lead, and 16 of sulphur. The sulphuret of antimony
mingled with its gangue may be subjected to the same mode of assay, and
the result will be still more direct, since the crude antimony is
brought into the market after being freed from its gangue by a simple
fusion.

The assay by washing is also had recourse to for ascertaining if the
_scoriæ_ or other products of the furnaces contain some metallic grains
which might be extracted from them by stamping and washing on the great
scale; a process employed considerably with the _scoriæ_ of tin and
copper works.

_Of assays by the dry way._--The assay by the dry way has for its
object, to show the nature and proportion of the metals contained in a
mineral substance. To make a good assay, however, it is indispensably
necessary to know what is the metal associated with it, and even within
certain limits, the quantity of the foreign bodies. Only one metal is
commonly looked after; unless in the case of certain argentiferous ores.
The mineralogical examination of the substances under treatment, is most
commonly sufficient to afford data in these respects; but the assays may
always be varied with different views, before stopping at a definite
result; and in every instance, only such assays can be confided in, as
have been verified by a double operation.

This mode of assaying requires only a little experience, with a simple
apparatus; and is of such a nature as to be practised currently in the
smelting works. The air furnace and crucibles employed are described in
all good elementary chemical books. These assays are usually performed
with the addition of a flux to the ore, or some agent for separating the
earthy from the metallic substances; and they possess a peculiar
advantage relative to the smelting operations, because they offer many
analogies between results on the great scale and experiments on the
small. This may even enable us often to deduce, from the manner in which
the assay has succeeded with a certain flux, and at a certain degree of
heat, valuable indications as to the treatment of the ore in the great
way. See FURNACE.

In the smelting houses which purchase the ore, as in Germany, it is
necessary to bestow much attention upon the assays, because they serve
to regulate the quality and the price of the schlichs to be delivered.
These assays are not by any means free from difficulties, especially
when ores containing several useful metals are treated, and which are to
be dosed or proportioned; ores, for example, including a notable
quantity of lead, copper, and silver, mixed together.

In the central works of the Hartz, as well as in those of Saxony, the
_schlichs_ as delivered are subjected to docimastic assays, which are
verified three times, and by three different persons, one of whom is
engaged for the interests of the mining partners, another for that of
the smelting house, and a third as arbiter in case of a difference. If
the first two results of assaying differ by 1/2 _loth_ (or 1/4 ounce) of
silver per cwt. of _schlich_, the operations must be resumed; but this
rarely happens. When out of the three assays, the one differs from the
two others by no more than 1/4 loth of silver per cwt., but by more in
one, and by less in another, the mean result is adopted. As to the
contents of the _schlich_ in lead, the mean results of the assays must
be taken. The differences allowed, are three pounds for the _schlich_,
when it contains from 12 to 30 per cent. of lead, increasing to six
pounds for _schlich_, when it contains less than 55 per cent. of that
metal.

Assaying forms in great establishments, an important object in reference
to time and expense. Thus, in the single work of Franckenscharn, in the
Hartz, no less than 300 assays have to be made in a threefold way, every
Monday, without taking into account the several assays of the smelting
products which take place every Thursday. Formerly fluxes more or less
compound were employed for these purposes, and every assay cost about
fifteen pence. At present all these assays are made more simply, by much
cheaper methods, and cost a penny farthing each upon an average.

_Of the assays by the humid way._--The assays by the humid way, not
reducible to very simple processes, are true chemical analyses, which
may in fact be applied with much advantage, either to ores, or to the
products of the furnace; but which cannot be expected to be practised in
smelting-houses, on account of the complication of apparatus and
reagents they require. Moreover, an expert chemist is necessary to
obtain results that can be depended on. The directors of
smelting-houses, however, should never neglect any opportunities that
may occur of submitting the materials operated upon, as well as their
products, to a more thorough examination than the dry way alone can
effect. One of the great advantages of similar researches is, to
discover and appreciate the minute quantities of injurious substances
which impair the malleability of the metals, which give them several bad
qualities, about whose nature and cause, more or less error and
uncertainty prevail. Chemical analysis, rightly applied to metallurgy,
cannot fail to introduce remarkable improvements into the
processes.--See the different metals, in their alphabetical places.

For assays in the dry way, both of stony and metallic minerals, the
process of Dr. Abich deserves recommendation. In consists in mixing the
pulverized mineral with 4 or 6 times its weight of carbonate of baryta
in powder, fusing the mixture at a white heat, and then dissolving it
after it cools, in dilute muriatic acid. The most refractory minerals,
even corundum, cyanite, staurolite, zircon, and felspar, yield readily
to this treatment. This process may be employed with advantage upon poor
refractory ores. The platinum crucible, into which the mixed materials
are put for fusion, should be placed in a Hessian crucible, and
surrounded with good coak.

       *       *       *       *       *

The following tabular view of the metallic produce of the British mines,
is given by two very skilful observers, in a work published in 1827,
entitled _Voyage Metallurgique en Angleterre, par MM. Dufrénoy et Elie
de Beaumont_:--

                                         Tons.       Tons.
  Tin        Cornwall alone                           3,160
           { Cornwall                    9,331 }
           { Devonshire                    537 }
           { Staffordshire                  38 }
  Copper   { Anglesey                      738 }
           { Wales                          55 }     11,469
           { Cumberland                     21 }
           { Ireland                       738 }
           { Scotland                       11 }
          {  Wales                       7,500  }
          {  Scotland                    2,800  }
  Lead    {  Cornwall and Devonshire       800  }    31,900
          {  Shropshire                    800  }
          {  Derbyshire                  1,000  }
          {  Cumberland                 19,000  }
  Cast Iron about                                   600,000[32]

  [32] I have converted the weights of lead and cast iron, given in
  kilogrammes, into tons, at the rate of 1000 kilogrammes per ton; which
  is sufficiently near.

The manganese raised in England exceeds 2000 tons.

M. Heron de Villefosse inserted in the last number of the _Annales des
Mines_ for 1827, the following statistical view of the metallic products
of France:--

                                                      Tons.
  Lead in pigs (_saumons_)                              103
  Litharge                                              513
  Sulphuret of lead, ground galena (_alquifoux_)        112
  Black copper                                          164
  Antimony                                               91
  Manganese                                             765
  Crude cast iron                                    25,606
  Bar iron                                          127,643
  Steel                                               3,500
  Silver in ingots                                        1-1/6

The total value of which is estimated at 80 millions of francs; or about
3,400,000 pounds sterling.


METALS; (_Metaux_, Fr.; _Metalle_, Germ.) are by far the most numerous
class of undecompounded bodies in chemical arrangements. They amount to
41; of which 7 form, with oxygen, bodies possessed of alkaline
properties; these are, 1. potassium; 2. sodium; 3. lithium; 4. barytium,
or barium; 5. strontium; 6. calcium; 7. magnesium; for even magnesia,
the last and feeblest base, tinges turmeric brown, and red cabbage
green. The next 5 metals form, with oxygen, the earths proper; they are,
8. yttrium; 9. glucinum; 10. alumium; 11. zirconium; 12. thorinum. The
remaining 29 may be enumerated in alphabetical order, as they hardly
admit of being grouped into subdivisions with any advantage. They are as
follows: 13. antimony; 14. arsenic; 15. bismuth; 16. cadmium; 17.
cerium; 18. chromium; 19. cobalt; 20. copper; 21. gold; 22. iridium; 23.
iron; 24. lead; 25. manganese; 26. mercury; 27. molybdenum; 28. nickel;
29. osmium; 30. palladium; 31. platinum; 32. rhodium; 33. silver; 34.
tantalum; 35. tellurium; 36. tin; 37. titanium; 38. tungstenium; 39.
vanadium; 40. uranium; 41. zinc.

1. They are all, more or less, remarkable for a peculiar lustre, called
the metallic. This property of strongly reflecting light, is connected
with a certain state of aggregation of their particles, but is
possessed, superficially at least, by mica, animal charcoal, selenium,
polished indigo;--bodies not at all metallic.

2. The metals are excellent conductors of caloric, and most of them also
of electricity, though probably not all. According to Despretz, they
possess the power of conducting heat according to the following
numbers:--Gold, 1000; platinum, 981; silver, 973; copper, 898; iron,
374; zinc, 363; tin, 304; lead, 179·6.

Becquerel gives the following table of metals, as to electrical
conduction:--

Copper, 100; gold, 93·6; silver, 73·6; zinc, 28·5; platina, 16·4; iron,
15·8; tin, 15·5; lead, 8·3; mercury, 3·5; potassium, 1·33.

The metals which hardly, if at all, conduct electricity, are, zirconium;
alumium; tantalum, in powder; and tellurium.

3. Metals are probably opaque; yet gold leaf, as observed by Newton,
seems to transmit the green rays, for objects placed behind it in the
sunbeam appear green. This phenomena has, however, been ascribed to the
rays of light passing through an infinite number of minute fissures in
the thinly hammered gold.

4. All metals are capable of combining with oxygen, but with affinities
and in quantities extremely different. Potassium and sodium have the
strongest affinity for it; arsenic and chromium, the feeblest. Many
metals become acids by a sufficient dose of oxygen, while, with a
smaller dose, they constitute salifiable bases.

5. Metals combine with each other, forming a class of bodies called
alloys, except when one of them is mercury, in which case the compound
is styled an amalgam.

6. They combine with hydrogen into _hydrurets_; with carbon, into
_carburets_; with sulphur, into _sulphurets_; with phosphorus, into
_phosphurets_; with selenium, into _seleniurets_; with boron, into
_borurets_ (_borides?_); with chlorine, into _chlorides_; with iodine,
into _iodides_; with cyanogen, into _cyanides_; with silicon, into
_silicides_; and with fluorine, into _fluorides_.

7. Metallic salts are definite compounds, mostly crystalline, of the
metallic oxides with the acids. See HALOID.


METEORITES, (_Aerolithes_, Fr.), are stones of a peculiar aspect and
composition, which have fallen from the air.


METHYLÈNE, a peculiar liquid compound of carbon and hydrogen, extracted
from pyroxilic spirit, which is reckoned to be a bi-hydrate of
_methylène_.


MICA, is a finely foliated mineral, of a pearly metallic lustre. It is
harder than gypsum, but not so hard as calc-spar; flexible and elastic;
spec. grav. 2·65. It is an ingredient of granite and gneiss. The large
sheets of mica exposed for sale in London, are mostly brought from
Siberia. They are used, instead of glass, to enclose the fire, without
concealing the flame, in certain stoves.

The mica of Fahlun, analyzed by Rose, afforded, silica, 46·22; alumina,
34·52; peroxide? of iron, 6·04; potash, 8·22; magnesia, with oxide of
manganese, 2·11; fluoric acid, 1·09; water, 0·98.


MICROCOSMIC SALT; a term given to a salt extracted from human urine,
because man was regarded by the alchemists as a miniature of the world,
or the microcosm. It is a phosphate of soda and ammonia; and is now
prepared by mixing, equivalent proportions of phosphate of soda and
phosphate of ammonia, each in solution, evaporating and crystallizing
the mixture. A small excess of ammonia aids the crystallization.


MILK; (_Lait_, Fr.; _Milche_, Germ.) owes its whiteness and opacity to
an emulsion composed of the caseous matter and butter, with sugar of
milk, extractive matters, salts, and free lactic acid; the latter of
which causes fresh milk to redden litmus paper. Milk, in general,
contains from 10 to 12 per cent. of solid matter, on being evaporated to
dryness by a steam heat. The mean specific gravity of cows’ milk is
1·030, but it is less if the milk be rich in cream. The specific gravity
of the skimmed milk is 1·035; and of the cream is 1·0244. 100 parts of
creamed milk, contain--

  Caseous matter, containing some butter,                         2·600
  Sugar of milk                                                   3·500
  Alcoholic extract, lactic acid, and lactates                    0·600
  Salts; muriate and phosphate of potash, and phosphate of lime   0·420
  Water                                                          92·875
  Cream consists of,--Butter separated by churning                4·5
  Caseous matter precipitated by the coagulation of the milk of
  the butter                                                      3·5
  Butter-milk                                                    92·0
                                                                -------
                                                                100·0

When milk contained in wire-corked bottles, is heated to the boiling
point in a water bath, the oxygen of the included small portion of air
under the cork seems to be carbonated, and the milk will afterwards keep
fresh, it is said, for a year or two; as green gooseberries and peas do
by the same treatment.


MILL-STONE, or BUHR-STONE. This interesting form of silica, which occurs
in great masses, has a texture essentially cellular, the cells being
irregular in number, shape, and size, and are often crossed by thin
plates, or coarse fibres of silex. The Buhr-stone has a straight
fracture, but it is not so brittle as flint, though its hardness is
nearly the same. It is feebly translucent; its colours are pale and
dead, of a whitish, grayish, or yellowish cast, sometimes with a tinge
of blue.

The Buhr-stones usually occur in beds, which are sometimes continuous,
and at others interrupted. These beds are placed amid deposits of sand,
or argillaceous and ferruginous marls, which penetrate between them,
filling their fissures and honeycomb cavities. Buhr-stones constitute a
very rare geological formation, being found in abundance only in the
mineral basin of Paris, and a few adjoining districts. Its place of
superposition is well ascertained: it forms a part of the lacustrine, or
fresh-water formation, which, in the locality alluded to, lies above the
fossil-bone gypsum, and the stratum of sand and marine sandstone which
cover it. Buhr-stone constitutes, therefore, the uppermost solid stratum
of the crust of the globe; for above it there is nothing but alluvial
soil, or diluvial gravel, sand, and loam.

Buhr-stones sometimes contain no organic forms, at others they seem as
if stuffed full of fresh-water shells, or land shells and vegetables of
inland growth. There is no exception known to this arrangement; but the
shells have assumed a siliceous nature, and their cavities are often
bedecked with crystals of quartz. The best Buhr-stones for grinding
corn, have about an equal proportion of solid matter, and of vacant
space. The finest quarry of them is upon the high ground, near _La
Ferté-sous-Jouarre_. The stones are quarried in the open air, and are
cut out in cylinders, from one to two yards in diameter, by a series of
iron and wooden wedges, gradually but equally inserted. The pieces of
buhr-stones are afterwards cut into parallelopipeds, called _panes_,
which are bound with iron hoops into large millstones. These pieces are
exported chiefly to England and America. Good millstones of a bluish
white colour, with a regular proportion of cells, when six feet and a
half in diameter, fetch 1200 francs a-piece, or 48_l._ sterling. A
coarse conglomerate sandstone or breccia is, in some cases, used as a
substitute for buhr-stones; but it is a poor one.


MINERAL WATERS. See SODA WATER, and WATERS, MINERAL.


MINES; (_Bergwerke_, Germ.) Amidst the variety of bodies apparently
infinite, which compose the crust of the globe, geologists have
demonstrated the prevalence of a few general systems of rocks, to which
they have given the name of _formations_ or _deposits_. A large
proportion of these mineral systems consists of parallel planes, whose
length and breadth greatly exceed their thickness; on which account they
are called stratified rocks; others occur in very thick blocks, without
any parallel stratification, or horizontal seams of considerable extent.

The stratiform deposits are subdivided into two great classes; the
primary and the secondary. The former seem to have been called into
existence before the creation of organic matter, because they contain no
exuviæ of vegetable or animal beings; while the latter are more or less
interspersed, and sometimes replete with organic remains. The primary
strata are characterized, moreover, by the nearly vertical or highly
inclined position of their planes; the secondary lie for the most part
in a nearly horizontal position.

Where the primitive mountains graduate down into the plains, rocks of an
intermediate character appear, which, though possessing a nearly
vertical position, contain a few vestiges of animal beings, especially
shells. These have been called _transition_, to indicate their being the
passing links between the first and second systems of ancient deposits;
they are distinguished by the fractured and cemented texture of their
planes, for which reason they are sometimes called conglomerate.

Between these and the truly secondary rocks, another very valuable
series is interposed in certain districts of the globe; namely, the
coal-measures, the paramount formation of Great Britain. The coal strata
are disposed in a basin-form, and alternate with parallel beds of
sandstone, slate-clay, iron-stone, and occasionally limestone. Some
geologists have called the coal-measures the medial formation.

In every mineral plane, the inclination and direction are to be noted;
the former being the angle which it forms with the horizon, the latter
the point of the azimuth or horizon, towards which it dips, as west,
north-east, south, &c. The direction of the bed is that of a horizontal
line drawn in its plane; and which is also denoted by the point of the
compass. Since the lines of direction and inclination are at right
angles to each other, the first may always be inferred from the second;
for when a stratum is said to dip to the east or west, this implies that
its direction is north and south.

The smaller sinuosities of the bed are not taken into account, just as
the windings of a river are neglected in stating the line of its course.

_Masses_ are mineral deposits, not extensively spread in parallel
planes, but irregular heaps, rounded or oval, enveloped in whole or in a
great measure by rocks of a different kind. Lenticular masses being
frequently placed between two horizontal or inclined strata, have been
sometimes supposed to be stratiform themselves, and have been
accordingly denominated by the Germans _liegende stocke_, _lying heaps_
or _blocks_.

The orbicular masses often occur in the interior of unstratified
mountains, or in the bosom of one bed.

_Nests_, _concretions_, _nodules_, are small masses found in the middle
of strata; the first being commonly in a friable state; the second often
kidney-shaped, or tuberous; the third nearly round, and encrusted, like
the kernel of an almond.

_Lodes_, or large veins, are flattened masses, with their opposite
surfaces not parallel, which consequently terminate like a wedge, at a
greater or less distance, and do not run parallel with the rocky strata
in which they lie, but cross them in a direction not far from the
perpendicular; often traversing several different mineral planes. The
_lodes_ are sometimes deranged in their course, so as to pursue for a
little way the space between two contiguous strata; at other times they
divide into several branches. The matter which fills the lodes is for
the most part entirely different from the rocks they pass through, or at
least it possesses peculiar features.

This mode of existence, exhibited by several mineral substances, but
which has been long known with regard to metallic ores, suggests the
idea of clefts or rents having been made in the stratum posterior to its
consolidation, and of the vacuities having been filled with foreign
matter, either immediately or after a certain interval. There can be no
doubt as to the justness of the first part of the proposition, for there
may be observed round many lodes undeniable proofs of the movement or
dislocation of the rock; for example, upon each side of the rent, the
same strata are no longer situated in the same plane as before, but make
greater or smaller angles with it; or the stratum upon one side of the
lode is raised considerably above, or depressed considerably below, its
counterpart upon the other side. With regard to the manner in which the
rent has been filled, different opinions may be entertained. In the
lodes which are widest near the surface of the ground, and graduate into
a thin wedge below, the foreign matter would seem to have been
introduced as into a funnel at the top, and to have carried along with
it in its fluid state portions of rounded gravel and organic remains. In
other cases, other conceptions seem to be more probable; since many
lodes are largest at their under part, and become progressively narrower
as they approach the surface; from which circumstance, it has been
inferred that the rent has been caused by an expansive force acting
from within the earth, and that the foreign matter, having been injected
in a fluid state, has afterwards slowly crystallized. This hypothesis
accounts much better than the other for most of the phenomena observable
in mineral veins, for the alterations of the rock at their sides, for
the crystallization of the different substances interspersed in them,
for the cavities bestudded with little crystals, and for many minute
peculiarities. Thus, the large crystals of certain substances which line
the walls of hollow veins, have sometimes their under surfaces
besprinkled with small crystals of sulphurets, arseniurets, &c., while
their upper surfaces are quite smooth; suggesting the idea of a slow
sublimation of these volatile matters from below, by the residual heat,
and their condensation upon the under faces of the crystalline bodies,
already cooled. This phenomenon affords a strong indication of the
igneous origin of metalliferous veins.

In the lodes, the principal matters which fill them are to be
distinguished from the accessory substances; the latter being
distributed irregularly, amidst the mass of the first, in crystals,
nodules, grains, seams, &c. The non-metalliferous exterior portion,
which is often the largest, is called _gangue_, from the German _gang_,
_vein_. The position of a vein is denoted, like that of the strata, by
the angle of inclination, and the point of the horizon towards which
they dip, whence the direction is deduced.

_Veins_, are merely small lodes, which sometimes traverse the great
ones, ramifying in various directions, and in different degrees of
tenuity.

A metalliferous substance is said to be _disseminated_, when it is
dispersed in crystals, spangles, scales, globules, &c., through a large
mineral mass.

Certain ores which contain the metals most indispensable to human
necessities, have been treasured up by the Creator in very bountiful
deposits; constituting either great masses in rocks of different kinds,
or distributed in lodes, veins, nests, concretions, or beds with stony
and earthy admixtures; the whole of which become the objects of mineral
exploration. These precious stores occur in different stages of the
geological formations; but their main portion, after having existed
abundantly in the several orders of the primary strata, suddenly cease
to be found towards the middle of the secondary. Iron ores are the only
ones which continue among the more modern deposits, even so high as the
beds immediately beneath the chalk, when they also disappear, or exist
merely as colouring matters of the tertiary earthy beds.

The strata of gneiss and mica-slate constitute in Europe the grand
metallic domain. There is hardly any kind of ore which does not occur
there in sufficient abundance to become the object of mining operations,
and many are found no where else. The transition rocks and the lower
part of the secondary ones, are not so rich, neither do they contain the
same variety of ores. But this order of things, which is presented by
Great Britain, Germany, France, Sweden, and Norway, is far from forming
a general law; since in equinoxial America the gneiss is but little
metalliferous; while the superior strata, such as the clay-schists, the
sienitic porphyries, the limestones, which complete the transition
series, as also several secondary deposits, include the greater portion
of the immense mineral wealth of that region of the globe.

All the substances of which the ordinary metals form the basis, are not
equally abundant in nature; a great proportion of the numerous mineral
species which figure in our classifications, are mere varieties
scattered up and down in the cavities of the great masses or lodes. The
workable ores are few in number, being mostly sulphurets, some oxides,
and carbonates. These occasionally form of themselves very large masses,
but more frequently they are blended with lumps of quartz felspar, and
carbonate of lime, which form the main body of the deposit; as happens
always in proper lodes. The ores in that case are arranged in small
layers parallel to the strata of the formation, or in small veins which
traverse the rock in all directions, or in nests or concretions
stationed irregularly, or finally disseminated in hardly visible
particles. These deposits sometimes contain apparently only one species
of ore, sometimes several, which must be mined together, as they seem to
be of contemporaneous formation; whilst, in other cases, they are
separable, having been probably formed at different epochs. In treating
of the several metals in their alphabetical order, I have taken care to
describe their peculiar geological positions, and the rocks which
accompany or mineralize them.

In mining, as in architecture, the best method of imparting instruction
is to display the master-pieces of the respective arts, which speak
clearly to the mind through the medium of the eye. It is not so easy,
however, to represent at once the general effect of a mine, as it is of
an edifice; because there is no point of sight from which the former can
be sketched at once, like the latter. The subterraneous structures
certainly afford some of the finest examples of the useful labours of
man, continued for ages, under the guidance of science and ingenuity;
but, however curious, beautiful, and grand in themselves, they cannot
become objects of a panoramic view. It is only by the lights of geometry
and geology that mines can be contemplated and surveyed, either as a
whole or in their details; and, therefore, these marvellous subterranean
regions, in which roads are cut many hundred miles long, are altogether
unknown or disregarded by men of the world. Should any of them,
perchance, from curiosity or interest, descend into these dark recesses
of the earth, they are prepared to discover only a few insulated
objects, which they may think strange or possibly hideous; but they
cannot recognize either the symmetrical disposition of mineral bodies,
or the laws which govern geological phenomena, and serve as sure guides
to the skilful miner in his adventurous search. It is by exact plans and
sections of subterraneous workings, that a knowledge of the nature,
extent, and distribution of mineral wealth, can be acquired.

[Illustration: 698. _A general view of mining operations._]

As there is no country in the world so truly rich and powerful, by
virtue of its mineral stores, as Great Britain, so there are no people
who ought to take a deeper interest in their scientific illustration. I
have endeavoured in the present article to collect from the most
authentic sources the most interesting and instructive examples of
mining operations.

To the magnificent work of Ville-Fosse, _Sur la Richesse Minerale_, no
longer on sale, I have to acknowledge weighty obligations; many of the
figures being copied from his great Atlas.

Lodes or mineral veins are usually distinguished by English miners into
at least four species. 1. The rake vein. 2. The pipe vein. 3. The flat
or dilated vein; and 4. The interlaced mass (_stock-werke_), indicating
the union of a multitude of small veins mixed in every possible
direction with each other, and with the rock.

1. The _rake_ vein is a perpendicular mineral fissure; and is the form
best known among practical miners. It commonly runs in a straight line,
beginning at the superficies of the strata, and cutting them downwards,
generally further than can be reached. This vein sometimes stands quite
perpendicular; but it more usually inclines or hangs over at a greater
or smaller angle, or slope, which is called by the miners the _hade_ or
_hading_ of the vein. The line of direction in which the fissure runs,
is called the _bearing of the vein_.

2. The _pipe_ vein resembles in many respects a huge irregular cavern,
pushing forward into the body of the earth in a sloping direction, under
various inclinations, from an angle of a few degrees to the horizon, to
a dip of 45°, or more. The pipe does not in general cut the strata
across like the rake vein, but insinuates itself between them; so that
if the plane of the strata be nearly horizontal, the bearing of the pipe
vein will be conformable; but if the strata stand up at a high angle,
the pipe shoots down nearly headlong like a shaft. Some pipes are very
wide and high, others are very low and narrow, sometimes not larger than
a common mine or drift.

3. The _flat_ or _dilated_ vein, is a space or opening between two
strata or beds of stone, the one of which lies above, and the other
below this vein, like a stratum of coal between its roof and pavement;
so that the vein and the strata are placed in the same plane of
inclination. These veins are subject, like coal, to be interrupted,
broken, and thrown up or down by slips, dykes, or other interruptions of
the regular strata. In the case of a metallic vein, a slip often
increases the chance of finding more treasure. Such veins do not
preserve the parallelism of their beds, characteristic of coal seams;
but vary excessively in thickness within a moderate space. Flat veins
occur frequently in limestone, either in a horizontal or declining
direction. The flat or strata veins open and close, as the rake veins
also do.

4. The interlaced mass has been already defined.

To these may be added the _accumulated_ vein, or irregular mass
(_butzenwerke_), a great deposit placed without any order in the bosom
of the rocks, apparently filling up cavernous spaces.

The interlaced masses are more frequent in primitive formations, than in
the others; and tin is the ore which most commonly affects this
locality. See figure of TIN mine.

The study of the mineral substances, called _gangues_ or vein-stones,
which usually accompany the different ores, is indispensable in the
investigation and working of mines. These _gangues_, such as quartz,
calcareous spar, fluor spar, heavy spar, &c., and a great number of
other substances, although of little or no value in themselves, become
of great consequence to the miner, either by pointing out by their
presence that of certain useful minerals, or by characterising in their
several associations, different deposits of ores of which it may be
possible to follow the traces, and to discriminate the relations, often
of a complicated kind, provided we observe assiduously the accompanying
_gangues_.

Mineral veins are subject to derangements in their course, which are
called shifts or faults. Thus, when a transverse vein throws out, or
intercepts, a longitudinal one, we must commonly look for the rejected
vein on the side of the obtuse angle which the direction of the latter
makes with that of the former. When a bed of ore is deranged by a fault,
we must observe whether the slip of the strata be upwards or downwards;
for in either circumstance, it is only by pursuing the direction of the
fault that we can recover the ore; in the former case by mounting, in
the latter by descending beyond the dislocation.

When two veins intersect each other, the direction of the _offcast_ is a
subject of interest, both to the miner and the geologist. In Saxony it
is considered as a general fact that the portion thrown out is always
upon the side of the obtuse angle, a circumstance which holds also in
Cornwall; and the more obtuse the angle, the out-throw is the more
considerable. A vein may be thrown out on meeting another vein, in a
line which approaches either towards its inclination or its direction.
The Cornish miners use two different terms to denote these two modes of
rejection; for the first case, they say the vein is _heaved_; for the
second, it is _started_.

[Illustration: 699]

The great copper lode of Carharack, _d_, _fig._ 699. in the parish of
Gwenap, is one of the most instructive examples of intersection. The
power or thickness of this vein is 8 feet; its direction is nearly due
east and west, and it dips towards the north at an inclination of two
feet per fathom; its upper part being in the _killas_ (a greenish
clay-slate); its lower part in the granite. The lode has suffered two
intersections; the first produced by meeting the vein _h_, called
_Steven’s fluckan_, which runs from north-east to south-west, and which
throws the lode several fathoms out; the second is produced by another
vein _i_, almost at right angles with the first, and which occasions
another out-throw of 20 fathoms to the right side. The fall of the vein
occurs therefore in the one case to the right, and in the other to the
left; but in both it is towards the side of the obtuse angle. This
distribution is very singular; for one part of the vein appears to have
mounted while the other has descended. N, S denotes North and South. _d_
is the copper lode running east and west. _h_, _i_, are systems of
clay-slate veins called fluckans; the line over S, represents the
down-shift, and _d´_ the up-shift.

_General observations on the localities of ores, and on the indications
of metallic mines._

1. _Tin_, exists principally in primitive rocks, appearing either in
interlaced masses, in beds, or as a constituent part of the rock itself,
and more rarely in distinct veins. Tin ore is found indeed sometimes in
alluvial land, filling up low situations between lofty mountains.

2. _Gold_, occurs either in beds, or in veins, frequently in primitive
rocks; though in other formations, and particularly in alluvial earth,
it is also found. When this metal exists in the bosom of primitive
rocks, it is particularly in schists; it is not found in serpentine, but
it is met with in greywacke in Transylvania. The gold of alluvial
districts, called gold of washing or transport, occurs, as well as
alluvial tin, among the debris of the more ancient rocks.

3. _Silver_, is found particularly in veins and beds, in primitive and
transition formations; though some veins of this metal occur in
secondary strata. The rocks richest in it are, gneiss, mica-slate,
clay-slate, greywacke, and old alpine limestone. Localities of
silver-ore itself are not numerous, at least in Europe, among secondary
formations; but it occurs in combination with the ores of copper or of
lead.

4. _Copper_, exists in the three mineral epochas; 1. in primitive rocks,
principally in the state of pyritous copper, in beds, in masses, or in
veins; 2. in transition districts, sometimes in masses, sometimes in
veins of copper pyrites; 3. in secondary strata, especially in beds of
cupreous schist.

5. _Lead_, occurs also in each of the three mineral epochas; abounding
particularly in primitive and transition grounds, where it usually
constitutes veins, and occasionally beds of sulphuretted lead (galena).
The same ore is found in strata or in veins among secondary rocks,
associated now and then with ochreous iron-oxide and calamine (carbonate
of zinc); and it is sometimes disseminated in grains through more recent
strata.

6. _Iron_, is met with in four different mineral eras, but in different
ores. Among primitive rocks, magnetic iron ore and specular iron ore
occur chiefly in beds, sometimes of enormous size; the ores of red or
brown oxide of iron (hæmatite) are found generally in veins, or
occasionally in masses with sparry iron, both in primitive and
transition rocks; as also sometimes in secondary strata; but more
frequently in the coal-measure strata, as beds of clay-ironstone, of
globular iron oxide, and carbonate of iron. In alluvial districts we
find ores of clay-ironstone, granular iron-ore, bog-ore, swamp-ore, and
meadow-ore. The iron ores which belong to the primitive period have
almost always the metallic aspect, with a richness amounting even to 80
per cent. of iron, while the ores in the posterior formations become in
general more and more earthy, down to those in alluvial soils, some of
which present the appearance of a common stone, and afford not more than
20 per cent. of metal, though its quality is often excellent.

7. _Mercury_, occurs principally among secondary strata, in disseminated
masses, along with combustible substances; though the metal is met with
occasionally in primitive countries.

8. _Cobalt_, belongs to the three mineral epochas; its most abundant
deposits are veins in primitive rocks; small veins containing this metal
are found, however, in secondary strata.

9. _Antimony_, occurs in veins or beds among primitive and transition
rocks.

10, 11. Bismuth and nickel do not appear to constitute the predominating
substance of any mineral deposits; but they often accompany cobalt.

12. _Zinc_, occurs in the three several formations: namely, as sulphuret
or blende, particularly in primitive and transition rocks; as calamine,
in secondary strata, usually along with oxide of iron, and sometimes
with sulphuret of lead.

An acquaintance with the general results collected and classified by
geology must be our first guide in the investigation of mines. This
enables the observer to judge whether any particular district, should
from the nature and arrangement of its rocks, be susceptible of
including within its bosom, beds of workable ores; it indicates also, to
a certain degree, what substances may probably be met with in a given
series of rocks, and what locality these substances will preferably
affect. For want of a knowledge of these facts, many persons have gone
blindly into researches equally absurd and ruinous.

Formerly indications of mines were taken from very unimportant
circumstances; from thermal waters, the heat of which was gratuitously
referred to the decomposition of pyrites; from mineral waters, whose
course is however often from a far distant source; from vapours
incumbent over particular mountain groups; from the snows melting faster
in one mineral district than another; from the different species of
forest trees, and from the greater or less vigour of vegetation, &c. In
general, all such indications are equally fallacious with the divining
rod, and the compass made of a lump of pyrites suspended by a thread.

Geognostic observation has substituted more rational characters of
metallic deposits, some of which may be called _negative_ and others
_positive_.

The _negative_ indications are derived from that peculiar geological
constitution, which from experience or general principles excludes
certain metallic matters; for example, granite, and in general every
primitive formation, forbids the hope of finding within them combustible
fossils (pit-coal), unless it be beds of anthracite; there also it would
be vain to seek for sal gem. It is very seldom that granite rocks
include silver; or limestones, ores of tin. Volcanic territories never
afford any metallic ores worth the working; nor do extensive veins
usually run into secondary and alluvial formations. The richer ores of
iron do not occur in secondary strata; and the ores of this metal
peculiar to these localities, do not exist among primary rocks.

Among _positive_ indications, some are proximate and others remote. The
proximate are, an efflorescence, so to speak, of the subjacent metallic
masses; magnetic attraction for iron ores; bituminous stone, or
inflammable gas for pit-coal; the frequent occurrence of fragments of
particular ores, &c. The remote indications consist in the geological
epocha, and nature of the rocks. From the examples previously adduced,
marks of this kind acquire new importance when in a district susceptible
of including deposits of workable ores, the _gangues_ or vein-stones are
met with which usually accompany any particular metal. The general
aspect of mountains whose flanks present gentle and continuous slopes,
the frequency of sterile veins, the presence of metalliferous sands, the
neighbourhood of some known locality of an ore, for instance that of
iron-stone in reference to coal, lastly the existence of salt springs
and mineral waters, may furnish some indications; but when ferruginous
or cupreous waters issue from sands or clays, such characters merit in
general little attention, because the waters may flow from a great
distance. No greater importance can be attached to metalliferous sands
and saline springs.

In speaking of remote indications, we may remark that in several places,
and particularly near Clausthal in the Hartz, a certain ore of red oxide
of iron occurs above the most abundant deposits of the ores of lead and
silver; whence it has been named by the Germans the _iron-hat_. It
appears that the iron ore rich in silver, which is worked in America
under the name of _pacos_, has some analogy with this substance; but
iron ore is in general so plentifully diffused on the surface of the
soil, that its presence can be regarded as only a remote indication,
relative to other mineral substances, except in the case of clay
ironstone with coal.

_Of the instruments and operations of subterranean operations._--It is
by the aid of geometry in the first place that the miner studies the
situation of the mineral deposits, on the surface and in the interior of
the ground; determines the several relations of the veins and the rocks;
and becomes capable of directing the perforations towards a suitable
end.

The instruments are, 1. the magnetic compass, which is employed to
measure the direction of a metallic ore, wherever the neighbourhood of
iron does not interfere with its functions; 2. the graduated semicircle
which serves to measure the inclination, which is also called the
clinometer.

3. The chain or cord for measuring the distance of one point from
another.

4. When the neighbourhood of iron renders the use of the magnet
uncertain, a plate or plane table is employed.

The dials of the compasses generally used in the most celebrated mines,
are graduated into hours; most commonly into twice 12 hours. Thus the
whole limb is divided into 24 spaces, each of which contains 15° = 1
hour. Each hour is subdivided into 8 parts.

_Means of penetrating into the interior of the earth._--In order to
penetrate into the interior of the earth, and to extract from it the
objects of his toils, the miner has at his disposal several means, which
may be divided into three classes: 1. _manual tools_, 2. _gunpowder_,
and 3. _fire_.

The tools used by the miners of Cornwall and Devonshire are the
following:

[Illustration: 700 701 702 703 704 705 706 708 710]

_Fig._ 700. The _pick_. It is a light tool, and somewhat varied in shape
according to circumstances. One side used as a hammer is called the
_poll_, and is employed to drive in the _gads_, or to loosen and detach
prominences. The _point_ is of steel, carefully tempered, and drawn
under the hammer to the proper form. The French call it _pointerolle_.

_Fig._ 701. The _gad_. It is a wedge of steel, driven into crevices of
rocks, or into small openings made with the point of the pick.

_Fig._ 702. The _miner’s shovel_. It has a pointed form, to enable it to
penetrate among the coarse and hard fragments of the mine rubbish. Its
handle being somewhat bent, a man’s power may be conveniently applied
without bending his body.

The _blasting_ or _shooting_ tools are:--

  A sledge or mallet          _fig._ 703.
  Borer                        --    704.
  Claying bar                  --    705.
  Needle or nail               --    706.
  Scraper                      --    707.
  Tamping bar                  --    708.

Besides these tools the miner requires a powder-horn, rushes to be
filled with gunpowder, tin cartridges for occasional use in wet ground,
and paper rubbed over with gunpowder or grease, for the _smifts_ or
fuses.

The _borer_, _fig._ 704., is an iron bar tipped with steel, formed like
a thick chisel, and is used by one man holding it straight in the hole
with constant rotation on its axis, while another strikes the head of it
with the iron sledge or mallet, _fig._ 703. The hole is cleared out from
time to time by the scraper, _fig._ 707., which is a flat iron rod
turned up at one end. If the ground be very wet, and the hole gets full
of mud, it is cleaned out by a stick bent at the end into a fibrous
brush, called a _swab-stick_.

[Illustration: 709]

_Fig._ 709. represents the plan of blasting the rock, and a section of a
hole ready for firing. The hole must be rendered as dry as possible,
which is effected very simply by filling it partly with tenacious clay,
and then driving into it a tapering iron rod, which nearly fills its
calibre, called the _claying bar_. This being forced in with great
violence, condenses the clay into all the crevices of the rock, and
secures the dryness of the hole. Should this plan fail, recourse is had
to tin cartridges furnished with a stem or tube (see _fig._ 710.,)
through which the powder may be inflamed. When the hole is dry, and the
charge of powder introduced, the _nail_, a small taper rod of copper, is
inserted so as to reach the bottom of the hole, which is now ready for
_tamping_. By this difficult and dangerous process, the gunpowder is
confined, and the disruptive effect produced. Different substances are
employed for _tamping_, or cramming the hole, the most usual one being
any soft species of rock free from siliceous or flinty particles. Small
quantities of it only are introduced at a time, and rammed very hard by
the _tamping-bar_, which is held steadily by one man, and struck with a
sledge by another. The hole being thus filled, the nail is withdrawn by
putting a bar through its eye, and striking it upwards. Thus a small
perforation or vent is left for the rush which communicates the fire.

Besides the improved tamping-bar faced with hard copper, other
contrivances have been resorted to for diminishing the risk of those
dreadful accidents that frequently occur in this operation. Dry sand is
sometimes used as a tamping material, but there are many rocks for the
blasting of which it is ineffective. Tough clay will answer better in
several situations.

For conveying the fire, the large and long green rushes which grow in
marshy ground are selected. A slit is made in one side of the rush,
along which the sharp end of a bit of stick is drawn, so as to extract
the pith, when the skin of the rush closes again by its own elasticity.
This tube is filled up with gunpowder, dropped into the vent-hole, and
made steady with a bit of clay. A paper _smift_, adjusted to burn a
proper time, is then fixed to the top of the rush-tube, and kindled,
when the men of the mine retire to a safe distance.

In _fig._ 709. the portion of the rock which would be dislodged by the
explosion, is that included between A and B. The charge of powder is
represented by the white part which fills the hole up to C; from which
point to the top, the hole is filled with _tamping_. The _smift_ is
shewn at D.

[Illustration: 711]

_Fig._ 711. is an iron bucket, or as it is called in Cornwall, a kibble,
in which the ore is raised in the shafts, by machines called _whims_,
worked by horses. The best kibbles are made of sheet-iron, and hold
each about three hundred weight of ore: 120 kibbles are supposed to
clear a cubic fathom of rock.

[Illustration: 712]

_Fig._ 712. represents the wheelbarrow used under ground for conveying
ore and waste to the foot of the shafts. It is made of light deal,
except the wheel, which has a narrow rim of iron.

[Illustration: 713]

_Fig._ 713. represents Mr. Taylor’s ingenious ventilator, or machine for
renewing fresh air in mines. It is so simple in construction, so
complete in its operation, requires so little power to work it, and is
so little liable to injury from wear, that nothing further of the kind
can be desired in ordinary metallic mines. The shaft of the mine is
represented at A; at either the top or bottom of which the machine may
be placed, as is found most convenient, but the foul air must be
discharged into a floor, furnished with a valve-door to prevent its
return into the mine. B is the air-pipe from the mine, passing through
the bottom of the fixed vessel or cylinder C, which is formed of timber,
and bound with iron hoops. It is filled with water nearly to the top of
the pipe B, on which is fixed a valve opening upwards at D. E, the air,
or exhausting cylinder of cast-iron, open at bottom, and suspended over
the air-pipe, but immersed some way in the water. It is furnished with a
wooden top, having an aperture fitted with a valve likewise opening
upwards at F. This exhausting cylinder is moved up and down by the _bob_
G, brought into connexion with any engine by the horizontal rod H; the
weight of the cylinder being balanced, if necessary, by the counterpoise
I. The action is as follows:--When the cylinder rises, the air from the
mine rushes up through the pipe and valve D; and when it descends, this
valve shuts, and prevents the return of the air, which is expelled
through the valve F. With a cylinder two feet in diameter and six feet
long, working from two to three strokes per minute, 200 gallons of air
may be discharged in the same time.

Gunpowder is the most valuable agent of excavation; possessing a power
which has no limit, and which can act every where, even under water. Its
introduction, in 1615, caused a great revolution in the mining art.

It is employed in mines in different manners, and in different
quantities, according to circumstances. In all cases, however, the
process resolves itself into boring a hole, and enclosing a cartridge in
it, which is afterwards made to explode. The hole is always cylindrical,
and is usually made by means of the borer, _fig._ 704., a stem of iron,
terminated by a blunt-edged chisel. It sometimes ends in a cross, formed
by two chisels set transversely. The workman holds the stem in his left
hand, and strikes it with an iron mallet held in his right. He is
careful to turn the punch a very little round at every stroke. Several
punches are employed in succession, to bore one hole; the first shorter,
the latter ones longer, and somewhat thinner. The rubbish is withdrawn
as it accumulates, at the bottom of the hole, by means of a picker,
which is a small spoon or disc of iron fixed at the end of a slender
iron rod. When holes of a large size are to be made, several men must
be employed; one to hold the punch, and one or more to wield the iron
mallet. The perforations are seldom less than an inch in diameter, and
18 inches deep; but they are sometimes 2 inches wide, with a depth of 50
inches.

The gunpowder, when used, is most commonly put up in paper cartridges.
Into the side of the cartridge, a small cylindrical spindle or _piercer_
is pushed. In this state the cartridge is forced down to the bottom of
the hole, which is then stuffed, by means of the tamping bar, _fig._
708., with bits of dry clay, or friable stones coarsely pounded.[33] The
piercer is now withdrawn, which leaves in its place, a channel through
which fire may be conveyed to the charge. This is executed either by
pouring gunpowder into that passage, or by inserting into it, reeds,
straw stems, quills, or tubes of paper filled with gunpowder. This is
exploded by a long match, which the workmen kindle, and then retire to a
place of safety.

  [33] Sir Rose Price invented a cap of bronze alloy, to tip the lower
  end of the iron rod; a contrivance now generally used in Cornwall.
  Before the Geological Society of that county introduced this invention
  into practice, scarcely a month elapsed without some dreadful
  explosion sending the miner to an untimely grave, or so injuring him
  by blowing out his eyes, or shattering his limbs, as to render him a
  miserable object of charity for the rest of his days. Scarcely has any
  accident happened since the employment of the new tamping-bar. When
  the whole bar was made of the tin and copper alloy it was expensive,
  and apt to bend; but the iron rod tipped with the bronze is both cheap
  and effectual. An ingenious instrument, called the shifting cartridge,
  was invented by Mr. Chinalls, and is described in the Transactions of
  the above society.

As the _piercer_ must not only be slender, but stiff, so as to be easily
withdrawn when the hole is tamped, iron spindles are usually employed,
though they occasionally give rise to sparks, and consequently to
dangerous accidents, by their friction against the sides of the hole.
Brass piercers have been sometimes tried; but they twist and break too
readily.

Each hole bored in a mine, should be so placed in reference to the
schistose structure of the rock, and to its natural fissures, as to
attack and blow up the least resisting masses. Sometimes the rock is
prepared beforehand for splitting in a certain direction, by means of a
narrow channel excavated with the small hammer.

The quantity of gunpowder should be proportional to the depth of the
hole, and the resistance of the rock; and merely sufficient to split it.
Anything additional would serve no other purpose than to throw the
fragments about the mine, without increasing the useful effect. Into the
holes of about an inch and a quarter diameter, and 18 inches deep, only
two ounces of gunpowder are put.

It appears that the effect of the gunpowder may be augmented by leaving
an empty space above, in the middle of, or beneath the cartridge. In the
mines of Silesia, the consumption of gunpowder has been eventually
reduced, without diminishing the product of the blasts, by mixing
sawdust with it in certain proportions. The hole has also been filled up
with sand in some cases, according to Mr. Jessop’s plan, instead of
being packed with stones, which has removed the danger of the tamping
operation. The experiments made in this way have given results very
advantageous in quarry blasts with great charges of gunpowder; but less
favourable in the small charges employed in mines.

Water does not oppose an insurmountable obstacle to the employment of
gunpowder; but when the hole cannot be made dry, a cartridge bag
impermeable to water must be had recourse to, provided with a tube also
impermeable, in which the _piercer_ is placed.

After the explosion of each mining charge, wedges and levers are
employed, to drag away and break down what has been shattered.

Wherever the rock is tolerably hard, the use of gunpowder is more
economical and more rapid than any tool-work, and is therefore always
preferred. A gallery, for example, a yard and a half high, and a yard
wide, the piercing of which by the hammer formerly cost from five to ten
pounds sterling, the running yard, in Germany, is executed at the
present day by gunpowder at from two to three pounds. When, however, a
precious mass of ore is to be detached, when the rock is cavernous,
which nearly nullifies the action of gunpowder, or when there is reason
to apprehend that the shock caused by the explosion may produce an
injurious fall of rubbish, hand-tools alone must be employed.

In certain rocks and ores of extreme hardness, the use both of tools and
gunpowder becomes very tedious and costly. Examples to this effect are
seen, in the mass of quartz mingled with copper pyrites, worked at
Rammelsberg, in the Hartz, in the masses of stanniferous granite of
Geyer and Altenberg in the Erzgebirge of Saxony, &c. In these
circumstances, fortunately very rare, the action of fire is used with
advantage to diminish the cohesion of the rocks and the ores. The
employment of this agent is not necessarily restricted to these
difficult cases. It was formerly applied very often to the working of
hard substances; but the introduction of gunpowder into the mining art,
and the increase in the price of wood, occasion fire to be little used
as an ordinary means of excavation, except in places where the
scantiness of the population has left a great extent of forest timber,
as happens at Kongsberg in Norway, at Dannemora in Sweden, at Felsobanya
in Transylvania, &c.

The action of fire may be applied to the piercing of a gallery, or to
the advancement of a horizontal cut, or to the crumbling down of a mass
of ore, by the successive upraising of the roof of a gallery already
pierced. In any of these cases, the process consists in forming
bonfires, the flame of which is made to play upon the parts to be
attacked. All the workmen must be removed from the mine during, and even
for some time after, the combustion. When the excavations have become
sufficiently cool to allow them to enter, they break down with levers
and wedges, or even by means of gunpowder, the masses which have been
rent and altered by the fire.

To complete our account of the manner in which man may penetrate into
the interior of the earth, we must point out the form of the excavations
that he should make in it.

In mines, three principal species of excavations may be distinguished;
viz. _shafts_, _galleries_, and the _cavities_ of greater or less
magnitude which remain in the room of the old workings.

A _shaft_ or _pit_ is a prismatic or cylindrical hollow space, the axis
of which is either vertical or much inclined to the horizon. The
dimension of the pit, which is never less than 32 inches in its
narrowest diameter, amounts sometimes to several yards. Its depth may
extend to 1000 feet, and more. Whenever a shaft is opened, means must be
provided to extract the rubbish which continually tends to accumulate at
its bottom, as well as the waters which may percolate down into it; as
also to facilitate the descent and ascent of the workmen. For some time
a wheel and axle erected over the mouth of the opening, which serve to
elevate one or two buckets of proper dimensions, may be sufficient for
most of these purposes. But such a machine becomes ere long inadequate.
Horse-whims, or powerful steam-engines, must then be had recourse to;
and effectual methods of support must be employed to prevent the sides
of the shaft from crumbling and falling down.

A _Gallery_ is a prismatic space, the straight or winding axis of which
does not usually deviate much from the horizontal line. Two principal
species are distinguished; the galleries of _elongation_, which follow
the direction of a bed or a vein; and the _transverse_ galleries, which
intersect this direction under an angle not much different from 90°. The
most ordinary dimensions of galleries are a yard wide, and two yards
high; but many still larger may be seen traversing thick deposits of
ore. There are few whose width is less than 24 inches, and height less
than 40; such small drifts serve merely as temporary expedients in
workings. Some galleries are several leagues in length. We shall
describe in the sequel the means which are for the most part necessary
to support the roof and the walls. The rubbish is removed by waggons or
wheelbarrows of various kinds. See _fig._ 712.

It is impossible to advance the boring of a shaft or gallery beyond a
certain rate, because only a limited set of workmen can be made to bear
upon it. There are some galleries which have taken more than 30 years to
perforate. The only expedient for accelerating the advance of a gallery,
is to commence, at several points of the line to be pursued, portions of
galleries which may be joined together on their completion.

Whether tools or gunpowder be used in making the excavations, they
should be so applied as to render the labour as easy and quick as
possible, by disengaging the mass out of the rock at two or three of its
faces. The effect of gunpowder, wedges, or picks, is then much more
powerful. The greater the excavation, the more important is it to
observe this rule. With this intent, the working is disposed in the form
of _steps_ (_gradins_), placed like those of a stair; each step being
removed in successive portions, the whole of which, except the last, are
disengaged on three sides, at the instant of their being attacked.

The substances to be mined occur in the bosom of the earth, under the
form of alluvial deposits, beds, pipe-veins, or masses, threads or small
veins, and rake-veins.

When the existence of a deposit of ore is merely suspected, without
positive proofs, recourse must be had to labours of research, in order
to ascertain the richness, nature, and disposition of a supposed mine.
These are divided into three kinds; _open workings_, _subterranean
workings_, and _boring operations_.

1. The _working by an open trench_, has for its object to discover the
outcropping or basset edges of strata or veins. It consists in opening a
fosse of greater or less width, which, after removing the vegetable
mould, the alluvial deposits, and the matters disintegrated by the
atmosphere, discloses the native rocks, and enables us to distinguish
the beds which are interposed, as well as the veins that traverse them.
The trench ought always to be opened in a direction perpendicular to the
line of the supposed deposit. This mode of investigation costs little,
but it seldom gives much insight. It is chiefly employed for verifying
the existence of a supposed bed or vein.

The _subterranean workings_ afford much more satisfactory knowledge.
They are executed by different kinds of perforations; viz. by
_longitudinal galleries_ hollowed out of the mass of the beds or veins
themselves, in following their course; by _transverse galleries_, pushed
at right angles to the direction of the veins; by _inclined shafts_,
which pursue the slope of the deposits, and are excavated in their mass;
or, lastly, by _perpendicular pits_.

If a vein or bed unveils itself on the flank of a mountain, it may be
explored, according to the greater or less slope of its inclination,
either by a longitudinal gallery opened in its mass, from the
outcropping surface, or by a transverse gallery falling upon it in a
certain point, from which either an oblong gallery or a sloping shaft
may be opened.

If our object be to reconnoitre a highly inclined stratum, or a vein in
a level country, we shall obtain it with sufficient precision, by means
of shafts, 8 or 10 yards deep, dug at 30 yards distance from one
another; excavated in the mass of ore, in the direction of its deposit.
If the bed is not very much inclined, only 45°, for example, vertical
shafts must be opened in the direction of its roof, or of the
superjacent rocky stratum, and galleries must be driven from the points
in which they meet the ore, in the line of its direction.

When the rocks which cover valuable minerals are not of very great
hardness, as happens generally with the coal formation, with pyritous
and aluminous slates, sal gem, and some other minerals of the secondary
strata, the _borer_ is employed with advantage to ascertain their
nature. This mode of investigation is economical, and gives, in such
cases, a tolerably exact insight into the riches of the interior. The
method of using the borer, has been described under ARTESIAN WELLS.

OF MINING IN PARTICULAR.

The mode of working mines is two-fold; by _open excavations_, and
_subterranean_.

Workings in the open air present few difficulties, and occasion little
expense, unless when pushed to a great depth. They are always preferred
for working deposits little distant from the surface; where, in fact,
other methods cannot be resorted to, if the substance to be raised be
covered with incoherent matters. The only rules to be observed are, to
arrange the workings in terraces, so as to facilitate the cutting down
of the earth; to transport the ores and the rubbish to their destination
at the least possible expense; and to guard against the crumbling down
of the sides. With the latter view, they ought to have a suitable slope,
or to be propped by timbers whenever they are not quite solid.

_Open workings_, are employed for valuable clays, sands, as also for the
alluvial soils of diamonds, gold, and oxide of tin, bog iron ores, &c.,
limestones, gypsums, building stones, roofing slates, masses of rock
salt in some situations, and certain deposits of ores, particularly the
specular iron of the island of Elba; the masses of stanniferous granite
of _Geyer_, _Altenberg_, and _Seyffen_, in the Erzgebirge, a chain of
mountains between Saxony and Bohemia; the thick veins or masses of black
oxide of iron of Nordmarch, Dannemora, &c., in Sweden; the mass of
cupreous pyrites of Ræraas, near Drontheim, in Norway; several mines of
iron, copper, and gold in the Ural mountains, &c.

_Subterranean workings_ may be conveniently divided into five classes,
viz.:--

1. Veins, or beds, much inclined to the horizon, having a thickness of
at least two yards.

2. Beds of slight inclination, or nearly horizontal, the power or
thickness of which does not exceed two yards.

3. Beds of great thickness, but slightly inclined.

4. Veins, or beds highly inclined, of great thickness.

5. Masses of considerable magnitude in all their dimensions.

_Subterranean mining_ requires two very distinct classes of workings;
the _preparatory_, and those for _extraction_.

The _preparatory_ consist in galleries, or in pits and galleries
destined to conduct the miner to the point most proper for attacking the
deposit of ore, for tracing it all round this point, for preparing
chambers of excavation, and for concerting measures with a view to the
circulation of air, the discharge of waters, and the transport of the
extracted minerals.

If the vein or bed in question be placed in a mountain, and if its
direction forms a very obtuse angle with the line of the slope, the
miner begins by opening in its side, at the lowest possible level, a
gallery of elongation, which serves at once to give issue to the waters,
to explore the deposit through a considerable extent, and then to follow
it in another direction; but to commence the real mining operations, he
pierces either shafts or galleries, according to the slope of the
deposit, across the first gallery.

For a stratum little inclined to the horizon, placed beneath a plain,
the first thing is to pierce two vertical shafts, which are usually made
to arrive at two points in the same line of slope, and a gallery is
driven to unite them. It is, in the first place, for the sake of
circulation of air that these two pits are sunk; one of them, which is
also destined for the drainage of the waters, should reach the lowest
point of the intended workings. If a vein is intersected by transverse
ones, the shafts are placed so as to follow, or, at least, to cut
through the intersections. When the mineral ores lie in nearly vertical
masses, it is right to avoid, as far as possible, sinking pits into
their interior. These should rather be perforated at one side of their
floor, even at some considerable distance, to avoid all risk of
crumbling the ores into a heap of rubbish, and overwhelming the workmen.

With a vein of less than two yards thick, as soon as the preparatory
labours have brought the miners to the point of the vein from which the
ulterior workings are to ramify, whenever a circulation of air has been
secured, and an outlet to the water and the matters mined, the first
object is to divide the mass of ore into large parallelopipeds, by means
of oblong galleries, pierced 20 or 25 yards below one another, with pits
of communication opened up, 30, 40, or 50 yards asunder, which follow
the slope of the vein. These galleries and shafts are usually of the
same breadth as the vein, unless when it is very narrow, in which case
it is requisite to cut out a portion of the roof or the floor. Such
workings serve at once the purposes of mining, by affording a portion of
ore, and the complete investigation of the nature and riches of the
vein, a certain extent of which is thus prepared before removing the
cubical masses. It is proper to advance first of all, in this manner, to
the greatest distance from the central point which can be mined with
economy, and afterwards to remove the parallelopiped blocks, in working
back to that point.

This latter operation may be carried on in two different ways; of which
one consists in attacking the ore from above; and another from below. In
either case, the excavations are disposed in steps similar to a stair
upon their upper or under side. The first is styled a _working_ in
direct or descending steps; and the second a _working_ in _reverse_, or
ascending steps.

[Illustration: 714]

1. Suppose, for example, that the post N, _fig._ 714., included between
the horizontal gallery A C, and the shaft A B, is to be excavated by
direct steps, a workman stationed upon a scaffold at the point _a_,
which forms the angle between the shaft and the elongated drift, attacks
the rock in front of him and beneath his feet. Whenever he has cut out a
parallelopiped (a rectangular mass), of from four to six yards broad,
and two yards high, a second miner is set to work upon a scaffold at
_a´_, two yards beneath the first, who, in like manner, excavates the
rock under his feet and before him. As soon as the second miner has
removed a post of four or six yards in width, by two in height, a third
begins upon a scaffold at _a´´_ to work out a third step. Thus, as many
workmen are employed as there are steps to be made between the two
oblong horizontal galleries which extend above and below the mass to be
excavated; and since they all proceed simultaneously, they continue
working in similar positions, in floors, over each other, as upon a
stair with very long wide steps. As they advance, the miners construct
before them wooden floors _c c c c_, for the purpose of supporting the
rubbish which each workman extracts from his own step. This floor, which
should be very solid, serves also for wheeling out his barrow filled
with ore. The round billets which support the planks sustain the roof or
the wall of the mineral vein or bed under operation. If the rubbish be
very considerable, as is commonly the case, the floor planks are lost.
However strongly they may be made, as they cannot be repaired, they
sooner or later give way under the enormous pressure of the rubbish; and
as all the weight is borne by the roof of the oblong gallery underneath,
this must be sufficiently timbered. By this ingenious plan, a great many
miners may go to work together upon a vein without mutual interference;
as the portions which they detach have always two faces at least free,
they are consequently more easily separable, either with gunpowder or
with the pick. Should the vein be more than a yard thick, or if its
substance be very refractory, two miners are set upon each step. _b b b
b_ indicate the quadrangular masses that are cut out successively
downwards; and 1 1, 2 2, 3 3, forwards; the lines of small circles are
the sections of the ends of the billets which support the floors.

[Illustration: 715]

2. To attack a mass Y, _fig._ 715., a scaffold _m_, is erected in one of
its terminal pits P P, at the level of the ceiling of the gallery R R´,
where it terminates below. A miner placed on this scaffold, cuts off at
the angle of this mass a parallelopiped 1, from one to two yards high,
by six or eight long. When he has advanced thus far, there is placed in
the same pit, upon another scaffold _m´_, a second miner, who attacks
the vein above the roof of the first cutting, and hews down, above the
parallelopiped 1, a parallelopiped of the same dimensions 1´, while the
first is taking out another 2, in advance of 1. When the second miner
has gone forward 6 or 8 yards, a third is placed also in the same pit.
He commences the third step, while the first two miners are pushing
forwards theirs, and so in succession.

In this mode of working, as well as in the preceding, it is requisite to
support the rubbish and the walls of the vein. For the first object, a
single floor _n n n_, may be sufficient, constructed above the lower
gallery, substantial enough to bear all the rubbish, as well as the
miners. In certain cases, an arched roof may be substituted; and in
others, several floors are laid at different heights. The sides of the
vein are supported by means of pieces of wood fixed between them
perpendicularly to their planes. Sometimes, in the middle of the
rubbish, small pits are left at regular distances apart, through which
the workmen throw the ore coarsely picked, down into the lower gallery.
The rubbish occasionally forms a slope _f f f_, so high that miners
placed upon it can work conveniently. When the rich portions are so
abundant as to leave too little rubbish to make such a sloping platform,
the miners plant themselves upon movable floors, which they carry
forward along with the excavations.

These two modes of working in the _step-form_, have peculiar advantages
and disadvantages; and each is preferred to the other according to
circumstances.

In the _descending workings_ or in _direct steps_, _fig._ 714., the
miner is placed on the very mass or substance of the vein; he works
commodiously before him; he is not exposed to the splinters which may
fly off from the roof; but by this plan he is obliged to employ a great
deal of timber to sustain the rubbish; and the wood is fixed for ever.

In the _ascending workings_, or in _reversed steps_, _fig._ 715., the
miner is compelled to work in the re-entering angle formed between the
roof and the front wall of his excavation, a posture sometimes
oppressive; but the weight of the ore conspires with his efforts to make
it fall. He employs less timber than in the _workings_ with _direct
steps_. The _sorting_ of the ore is more difficult than in the
_descending working_, because the rich ore is sometimes confounded with
the heap of rubbish on which it falls.

When seams of diluvium or gravel-mud, occur on one of the sides of the
vein, or on both, they render the quarrying of the ore more easy, by
affording the means of uncovering the mass to be cut down, upon an
additional face.

Should the vein be very narrow, it is necessary to remove a portion of
the sterile rock which encloses it, in order to give the work a
sufficient width to enable the miner to advance. If, in this case, the
vein be quite distinct from the rock, the labour may be facilitated, as
well as the separation of the ore, by disengaging the vein, on one of
its faces through a certain extent, the rock being attacked separately.
This operation is called _stripping the vein_. When it is thus
uncovered, a shot of gunpowder is sufficient to detach a great mass of
it, unmixed with sterile stones.

By the methods now described, only those parallelopipeds are cut out,
either in whole or in part, which present indications of richness
adequate to yield a prospect of benefit. In other cases, it is enough to
follow out the threads of ore which occur, by workings made in their
direction.

The miner, in searching within the crust of the earth for the riches
which it conceals, is exposed to many dangers. The rocks amidst which he
digs are seldom or never entire, but are almost always traversed by
clefts in various directions, so that impending fragments threaten to
fall and crush him at every instant. He is even obliged at times to cut
through rotten friable rocks or alluvial loams. Fresh atmospheric air
follows him with difficulty in the narrow channels which he lays open
before him; and the waters which circulate in the subterranean seams and
fissures filter incessantly into his excavation, and tend to fill it.
Let us now take a view of the means he employs to escape from these
three classes of dangers.

1. _Of the timbering of excavations._--The excavations of mines, are
divisible into three principal species; _shafts_, _galleries_, and
_chambers_. When the width of these excavations is inconsiderable, as is
commonly the case with shafts and galleries, their sides can sometimes
stand upright of themselves; but more frequently they require to be
propped or stayed by billets of wood, or by walls built with bricks or
stones; or even by stuffing the space with rubbish. These three kinds of
_support_ are called _timbering_, _walling_, and _filling up_.

Timbering is most used. It varies in form for the three species of
excavations, according to the solidity of the walls which it is destined
to sustain.

[Illustration: 716]

In a gallery, for example, it may be sufficient to support merely the
roof, by means of joists placed across, bearing at their two ends in the
rock; or the roof and the two walls by means of an upper joist S, _fig._
716., which is then called a _cap_ or _cornice beam_, resting on two
lateral upright posts or _stanchions_, _a_, _b_, to which a slight
inclination towards each other is given, so that they approach a little
at the top, and rest entirely upon the floor. At times, only one of the
walls and the roof need support. This case is of frequent occurrence in
pipe veins. Pillars are then set up only on one side, and on the other
the joists rest in holes of the rock. It may happen that the floor of
the gallery shall not be sufficiently firm to afford a sure foundation
to the standards; and it may be necessary to make them rest on a
horizontal piece called the _sole_. This is timbering with _complete
frames_. The upright posts are usually set directly on the sole; but the
extremities of the _cap_ or ceiling, and the upper ends of the
_standards_, are mortised in such a manner that these cannot come
nearer, whereby the cap shall possess its whole force of resistance. In
friable and shivery rocks there is put behind these beams, both upon the
ceiling and the sides, _facing boards_, which are planks placed
horizontally, or spars of cleft wood, set so close together as to leave
no interval. They are called _fascines_ in French. In ordinary ground,
the miner puts up these _planks_ in proportion as he goes forwards; but
in a loose soil, such as sand or gravel, he must mount them a little in
advance. He then drives into the mass behind the wooden frame-work,
thick but sharp-pointed planks or stakes, and which, in fact, form the
sides of the cavity, which he proceeds to excavate. Their one extremity
is thus supported by the earth in which it is thrust, and their other
end by the last framing. Whenever the miner gets sufficiently on, he
sustains the walls by a new frame. The size of the timber, as well as
the distance between the frames or _stanchions_, depends on the degree
of pressure to be resisted.

When a gallery is to serve at once for several distinct purposes, a
greater height is given to it; and a flooring is laid on it at a certain
level. If, for example, a gallery is to be employed, both for the
transport of the ores and the discharge of the waters, a floor _e e_,
_fig._ 715., is constructed above the bottom, over which the carriages
are wheeled, and under which the waters are discharged.

The timbering of shafts varies in form, as well as that of galleries,
according to the nature and the locality of the ground which they
traverse, and the purposes which they are meant to serve. The shafts
intended to be stayed with timber are usually square or rectangular,
because this form, in itself more convenient for the miner, renders the
execution of the timbering more easy. The wood-work consists generally
of rectangular frames, the spars of which are about eight inches in
diameter, and placed at a distance asunder of from a yard to a yard and
a half. The spars are never placed in contact, except when the pressure
of the earth and the waters is very great. The pieces composing the
frames are commonly united by a half-check, and the longer of the two
pieces extends often beyond the angles, to be rested in the rock.
Whether the shaft is vertical or inclined, the frame-work is always
placed so that its plane may be perpendicular to the axis of the pit. It
happens sometimes in inclined shafts that there are only two sides, or
even a single one, which needs to be propped. These are stayed by means
of cross beams, which rest at their two ends in the rock. When the
frames do not touch one another, strong planks or stakes are fastened
behind them to sustain the ground. To these planks the frames are firmly
connected, so that they cannot slide. In this case the whole timbering
will be supported, when the lower frame is solidly fixed, or when the
pieces from above pass by its angles to be abutted upon the ground.

In the large rectangular shafts, which serve at once for extracting the
ores, for the discharge of the waters, and the descent of the workmen,
the spaces destined for these several purposes are in general separated
by partitions, which also serve to increase the strength of the
timberings, by acting as buttresses to the planks in the long sides of
the frame-work. Occasionally a partition separates the ascending from
the descending basket, to prevent their jostling.--Lastly, particular
passages are left for ventilation.

As it is desirable that the wood shall retain its whole force, only
those pieces are squared which absolutely require it. The spars of the
frames in shafts and galleries are deprived merely of their bark, which
by holding moisture, would accelerate the decomposition of the wood. The
alburnum of oak is also removed.

Resinous woods, like the pine, last much shorter than the oak, the
beech, and the cherry-tree; though the larch is used with advantage. The
oak has been known to last upwards of 40 years; while the resinous woods
decay frequently in 10. The fresher the air in mines, the more durable
is the timbering.

[Illustration: 717 718]

The marginal _figs._ 717, 718. represent two vertical sections of a
shaft, the one at right angles to the other, with the view of showing
the mode of sustaining the walls of the excavation by timbering. It is
copied from an actual mine in the Hartz. There we may observe the spaces
allotted to the descent of the miners by ladders, to the drainage of the
waters by pumps P, and rods _t_, and to the extraction of the mineral
substances by the baskets B. _a_, _b_, _c_, _f_, _h_, _k_, various cross
timbers; A, C, E, upright do.; R, pump cistern; V, W, corve-ways. The
shafts here shown, are excavated in the line of the vein itself,--the
rock enclosing it being seen in the second figure.

In a great many mines it is found advantageous to support the
excavations by brick or stone buildings, constructed either with or
without mortar. These constructions are often more costly than wooden
ones, but they last much longer, and need fewer repairs. They are
employed instead of timberings, to support the walls and roof of
galleries, to line the sides of shafts, and to bear up the roofs of
excavations.

Sometimes the two sides of a gallery are lined with vertical walls, and
its roof is supported by an ogee vault, or an arch. If the sides of the
mine are solid, a simple arch is sufficient to sustain the roof and at
other times the whole surface of a gallery is formed of a single
elliptic vault, the great axis of which is vertical; and the bottom is
surmounted by a wooden plank, under which the waters run off; see _fig._
719.

Walled shafts also are sometimes constructed in a circular or elliptic
form, which is better adapted to resist the pressure of the earth and
waters. Rectangular shafts of all dimensions, however, are frequently
walled.

The sides of an excavation may also be supported by filling it
completely with rubbish. Wherever the sides need to be supported for
some time without the necessity of passing along them, it is often more
economical to stuff them up with rubbish, than to keep up their
supports. In the territory of Liege, for example, there have been shafts
thus filled up for several centuries; and which are found to be quite
entire when they are emptied. The rubbish is also useful for forming
roads among steep strata, for closing air-holes, and forming canals of
ventilation.

[Illustration: 719 720 721 722]

_Figs._ 719. 720. 721. represent the principal kinds of mason-work
employed in the galleries and shafts of mines. _Fig._ 722. exhibits the
walling in of the cage of an overshot water-wheel, as mounted within a
mine. Before beginning to build, an excavation large enough must be
made in the gallery to leave a space three feet and a half high for the
workmen to stand in, after the brick-work is completed. Between the two
opposite sides, cross beams of wood must be fixed at certain distances,
as chords of the vault, over which the rock must be hollowed out to
receive the arch-stones, and the centring must then be placed, covered
with deals to receive the _voussoirs_, beginning at the flanks and
ending with the key-stone. When the vault is finished through a certain
extent, the interval between the arch and the rock must be rammed full
of rubbish, leaving passages if necessary through it and the arch, for
currents of water.

In walling galleries, attention must be paid to the direction of the
pressure, and to build vertically or with a slope accordingly. Should
the pressure be equal in all directions, a closed vault, like _fig._
719., should be formed. For walls not far from the vertical, salient or
buttressed arches are employed, as shown in _fig._ 720., called in
German _überspringende bogen_; for other cases, twin-arches are
preferred, with an upright wall between.

_Fig._ 721. is a transverse section of a walled drain-gallery, from the
grand gallery of the Hartz; see also _fig._ 722. _a_ is the rock which
needs to be supported only at the sides and top; _b_, the masonwork, a
curve formed of the three circular arcs upon one level; _c_, the floor
for the watercourse. _Fig._ 719. is a cross section of a walled gallery,
as at Schneeberg, Rothenburg, Idria, &c.; _d_, is the rock, which is not
solid either at the flanks, roof, or floor; _e_, the elliptic masonwork;
_f_, the wooden floor for the waggons, which is sometimes, however,
arched in brick to allow of a watercourse beneath it.

_Fig._ 720. shows two vertical projections of a portion of a walled
shaft with buttresses, as built at the mine _Vater Abraham_, near
Marienberg. J is a section in the direction of the vein _g h_, to show
the roof of the shaft. I, a section exhibiting the slope of the vein _g
h_, into which the shaft is sunk; _m_ is the wall of the vein; _k_ is
the roof of the same vein; _n_, buttresses resting upon the flanks of
the shaft; _g_, great arcs on which the buttresses bear; _y_, vertical
masonwork; _z_, a wall which divides the shaft into two compartments, of
which the larger _p_ is that for extracting the ore, and the smaller for
the draining and descent of the miners.

_Fig._ 722. C D is the shaft in which the vertical crank-rods _c g_, _e
d_, move up and down. F, is a double hydraulic wheel, which can be
stopped at pleasure by a brake mounted upon the machine of extraction.
G, is the drum of the gig or whim for raising the _corves_ or tubs
(_tonnes_); H, is the level of the ground, with the carpentry which
supports the whim and its roof. _k_, is the key-stone of the _ogee_ arch
which covers the water-wheel; _a_, is the opening or window, traversed
by the extremity of the driving shaft, upon each side of the
water-wheel, through which a workman may enter to adjust or repair it;
_c b_, line of conduits for the streams of water which fall upon the
hydraulic wheel; _c_, _g_, double crank with rods, whose motion is
taken off the left side of the wheel; _e_, _d_, the same upon the right
side. The distance from H to F is about 22 yards.

_Figs._ 723. 724. present two vertical sections of the shaft of a mine
walled, like the roof of a cavern, communicating with the galleries of
the roof and the wall of the vein, and well arranged for both the
extraction of the ore, and the descent of the miners. The vertical
partition of the shaft for separating the passage for the corves or tubs
from the ladders is omitted in the figure, for the sake of clearness.

[Illustration: 723 724]

In _fig._ 723., A, B are the side walls supported upon the buttresses C
and D; in _fig._ 724., E is the masonry of the wall, borne upon the arch
F at the entrance to a gallery; the continuation being at G, which is
sustained by a similar arch built lower.

L, is the vault arch of the roof, supported upon another vault M, which
presents a double curvature, at the entrance of a gallery; at H is the
continuation of the arch or vault L, which underneath is supported in
like manner at the entrance of a lower gallery.

_a b_, _c d_, _fig._ 723., are small upright guide-bars or rods for one
of the corves, or kibbles.

_e f_, _g h_, are similar guide-bars for the other corf.

_i i_, are cross-bars of wood, which support the stays of the ladders of
descent.

_k k_, are also cross-bars by which the guide-rods are secured.

_t_, a _corf_, or extraction kibble, furnished with friction rollers;
the other corf is supposed to be drawn up to a higher level, in the
other vertical passage.

[Illustration: 725 726]

_Figs._ 725. 726. represent in a vertical section the mode of timbering
the galleries of the silver and lead mines at Andreasberg in the Hartz.
_Fig._ 725. shows the plan viewed from above. Upon the roof of the
timbering, the workman throws the waste rubbish, and in the empty space
below, which is shaded black, he transports in his waggons or
wheelbarrows the ores towards the mouth of the mine. _Fig._ 726. is the
cross section of the gallery. In the two figures, _a_ represents the
rock, and _b_ the timbering; round which there is a garniture of small
spars or lathes for the purpose of drainage and ventilation, with the
view of promoting the durability of the wood-work.

The working of minerals by the _mass_ is well exemplified a few leagues
to the north of Siegen, near the village of Müsen, in a mine of iron and
other metals, called _Stahlberg_, which forms the main wealth of the
country. The plan of working is termed _the excavation of a direct or
transverse mass_. It shows in its upper part the danger of bad mining,
and in its inferior portion, the regular workings, by whose means art
has eventually prevented the destruction of a precious mineral deposit.

[Illustration: 727]

_Fig._ 727. is a vertical section of the bed of ore, which is a _direct_
mass of spathose iron, contained in transition rock (greywacke). _a_,
_a_, _a_, are pillars of the sparry ore, reserved to support the
successive stages or floors, which are numbered 1. 2. 3. &c.; _b_, _b_,
_b_, are excavations worked in the ore; which exhibit at the present day
several floors of arches, of greater or less magnitude, according to the
localities. It may be remarked, that where the metallic deposit forms
one entire mass, rich in spathose iron ore of good quality, there is
generally given to the vaults a height of three fathoms; leaving a
thickness over the roof of two fathoms, on account of the numerous
fissures which pervade the mass. But where this mass is divided into
three principal branches, the roof of the vaults has only a fathom and a
half of thickness, while the excavation is three fathoms and a half
high. In the actual state of the workings, it may be estimated that from
all this direct mass, there is obtained no more out of every floor than
one-third of the mineral. Two-thirds remain as labours of reserve, which
may be resumed at some future day, in consequence of the regularity and
the continuation of the subterranean workings. _e_ is a shaft for
extraction, communicating below with the gallery of efflux _k_; _h_ is
an upper gallery of drainage, which runs in different directions (one
only being visible in this section) over a length of 400 fathoms. The
lower gallery _k_ runs 646 fathoms in a straight line. The mine of
Stahlberg has furnished annually on an average since 1760 about 25,000
cubic feet (French) of an excellent spathose ore of iron. _m m_,
represents the mass of sparry iron.

_Figs._ 728, 729, 730. represent the cross system of mining, which
consists in forming galleries through a mineral deposit, from its wall
or floor towards its roof, and not, as usual, in the direction of its
length. This mode was contrived towards the middle of the 18th century,
for working the very thick veins of the Schemnitz mine in Hungary, and
it is now employed with advantage in many places, particularly at Idria
in Carniola. In the two sections _figs._ 728., 730., as well as in the
ground plan _fig._ 729., the wall is denoted by _m m_, and the roof by
_t t_. A first gallery of prolongation E F, _fig._ 730., being formed to
the wall, transverse cuts, _a a_, are next established at right angles
to this gallery, so that between every two there may be room enough to
place three others, _b_, _c_, _b_, _fig._ 729. From each of the cuts
_a_, ore is procured by advancing with the help of timbering, till the
roof _t_ be reached. When this is done, these first cuts _a_, are filled
up with rubbish, laid upon pieces of timber with which the ground is
covered, so that if eventually, it should be wished to mine underneath,
no downfall of detritus is to be feared. These heaps of rubbish rise
only to within a few inches of the top of the cuts _a_, in order that
the working of the upper story may be easier, the bed of ore being there
already laid open upon its lower face.

[Illustration: 728 729 730]

In proportion as the cuts _a_, of the first story E F, are thus filled
up, the greater part of the timbering is withdrawn, and made use of
elsewhere. The intermediate cuts _b_, _c_, _b_, are next mined in like
manner, either beginning with the cuts _c_, or the cuts _b_, according
to the localities. From _fig._ 729. it appears that the working may be
so arranged, that in case of necessity, there may be always between two
cuts in activity the distance of three cuts, either not made, or filled
up with rubbish. Hence, all the portion of the bed of ore may be
removed, which corresponds to a first story E F _fig._ 730., and this
portion is replaced by rubbish.

The exploration of the upper stories E´ F´, E² F², E³ F³, is now
prepared in a similar manner; with which view shafts _h h_³, _k k_³, are
formed from below upwards in the wall _m_ of the deposit, and from these
shafts oblong galleries proceed, established successively on a level
with the stories thus raised over one another. See _fig._ 730. The
following objects may be specified in the figures:--

_a a_, the first cuts filled up with rubbish, upon the first story E F,
_fig._ 729.

_b b_, other cuts subsequently filled up, upon the same story.

_c_, the cut actually working.

_d_, the front of the cut, or place of actual excavation of the mineral
deposit.

_e_, masses of the barren rock, reserved in the cutting, as pillars of
safety.

_f_, galleries, by means of which the workmen may turn round the mass
_e_, in order to form, in the roof _t_, an excavation in the direction
of the deposit.

_g_, rubbish behind the mass _e_.

_k k_, two shafts leading from the first story E F, to the upper stories
of the workings, as already stated.

_m_, the wall, and _t_ the roof of the mineral bed.

In the second story E´ F´, the gallery of prolongation F´, _figs._ 728.
and 730., is not entirely perforated; but it is further advanced than
that of the third story, which, in its turn, is more than the gallery of
the fourth.

From this arrangement there is produced upon _fig._ 730. the general
aspect of a working by reversed steps.

Whenever the workings of the cuts _c_ in the first story are finished,
those of the second, _a´ a´_, may be begun in the second; and thus by
mounting from story to story, the whole deposit of ore may be taken out
and replaced with rubbish. One great advantage of this method is, that
nothing is lost; but it is not the only one. The facilities offered by
the system of _cross workings_ for disposing of the rubbish, most
frequently a nuisance to the miner, and expensive to get rid of, the
solidity which it procures by the banking up, the consequent economy of
timbering, and saving of expense in the excavation of the rock,
reckoning from the second story, are so many important circumstances
which recommend this mode of mining. Sometimes, indeed, rubbish may be
wanted to fill up, but this may always be procured by a few accessory
perforations; it being easy to establish in the vicinity of the workings
a vast excavation in the form of a vault, or kind of subterraneous
quarry, which may be allowed to fall in with proper precautions, and
where rubbish will thus accumulate in a short time, at little cost.

[Illustration: 731]

_Fig._ 731. represents a section of the celebrated lead mines of
Bleyberg in Carinthia, not far from Villach.

_b_, _c_, is the ridge of the mountains of compact limestone, in whose
bosom the workings are carried on.

_e_, is the metalliferous valley, running from east to west, between the
two parallel valleys of the Gail and the Drave, but at a level
considerably above the waters of these rivers.

_f g_, is the direction of a great many vertical beds of metalliferous
limestone.

On considering the direction and dip of the marly schist, and
metalliferous limestone, in the space _w_, _w_, to the west of the line
1, _s_, it would appear that a great portion of this system of mountains
has suffered a slip between 1, _s_, and a parallel one towards the east;
whereby, probably, that vertical position of the strata has been
produced, which exists through a considerable extent. The metalliferous
limestone is covered to a certain thickness with a marly schist, and
other more recent rocks. It is in this schist that the fine marble known
under the name of the _lumachella of Bleyberg_ is quarried.

The galena occurs in the bosom of this rock in flattened masses, or
blocks of a considerable volume, which are not separated from the rest
of the calcareous beds by any seam. It is accompanied by zinc ore
(_calamine_), especially in the upper parts of the mountain.

Several of the workable masses are indicated by _r_, _r_³; each presents
itself as a solid analogous to a very elongated ellipse, whose axis
dips, not according to the inclination of the surrounding rock, but to
an oblique or intermediate line between this inclination, and the
direction of the beds of limestone; as shown by _r w_, _r´ u_. Every
thing indicates the contemporaneous formation of the limestone, and the
lying beds of the lead ore.

The accidents or faults called _kluft_ (_rent_) at Bleyberg are visible
on the surface of the ground. Experienced miners have remarked that the
rich masses occur more frequently in the direction of these accidents
than elsewhere.

It is in general by galleries cut horizontally in the body of the
mountain, and at different levels, _s_, _g_, _s f_, that the miner
advances towards the masses of ore _r_, _r_³. Many of these galleries
are 500 fathoms long before they reach a workable mass. The several
galleries are placed in communication by a few shafts, such as _t_; but
few of these are sunk deeper than the level of the valley _e_.

The total length of the mines of Bleyberg is about 10,000 yards,
parallel to the valley _e_; in which space there are 500 concessions
granted by the government to various individuals or joint stock
societies, either by themselves or associated with the government.

The metalliferous valley contains 5000 inhabitants, all deriving
subsistence from the mines; 300 of whom are occupied in the government
works.

Each concession has a number and a name; as Antoni, Christoph, Matthæus,
Oswaldi, 2, 8, 36, &c.

[Illustration: 732]

_Fig._ 732 is a section in the quicksilver mine of Idria. 1. is the
gray-limestone; 2. is a blackish slate; 5. is a grayish slate.
Immediately above these transition rocks lies the bed containing the
ores called _corallenerz_, which consist of an intimate mixture of
sulphuret of mercury and argillaceous limestone; in which four men can
cut out, in a month, 2-1/2 toises cube of rock.

[Illustration: 733]

_Fig._ 733. represents a section of part of the copper mine of
Mansfeldt; containing the cellular limestone, called _rauchwacke_,
always with the compact marl-limestone called zechstein; the cupreous
schist, or _kupferschiefer_; the wall of grayish-white sandstone, called
the _weisse liegende_; and the wall of red sandstone, or the _rothe
liegende_. The thin dotted stratum at top is vegetable mould; the large
dotted portion to the right of the figure is oolite; the vein at its
side is sand; next is _rauchwacke_; and lastly, the main body of fetid
limestone, or _stinkstein_.

[Illustration: 734]

_Fig._ 734. represents one of the Mansfeldt copper schist mines in the
district called Burgoerner, or Preusshoheit.

1. Vegetable mould, with siliceous gravel.

2. Ferruginous clay or loam.

3. Sand, with fragments of quartz.

4. Red clay, a bed of variable thickness as well as the lower strata,
according as the cupreous schist is nearer or farther from the surface.

5. Oolite (_roogenstein_).

6. Newer variegated sandstone, (_bunter sandstein_).

7. Newer gypsum; below which, there is

8. A bluish marly clay.

9. Stinkstone, or lucullite.

10. Friable grayish marl.

11. Older gypsum, a rock totally wanting in the other districts of the
mines of Rothenberg; but abounding in Saxon Mansfeldt, where it includes
vast caverns known among the miners by the name of _schlotten_, as
indicated in the figure.

12. The calcareous rock called _zechstein_. The lower part of this
stratum shows symptoms of the cupriferous schist that lies underneath.
It presents three thin bands, differently modified, which the miner
distinguishes as he descends by the names of the sterile or rotten
(_faüle_) rock; the roof (_dachklotz_); and the main rock (_oberberg_.)

13. Is a bed of cupriferous schist (_kupferschiefer_), also called the
_bitumino-marly_ schist, in which may be noted, in going down, but not
marked in the figure:--

  _a_, the _lochberg_, a seam 4 inches thick.
  _b_, the _kammschale_, 1/4 of an inch thick.
  _c_, the _kopfschale_, one inch thick.

These seams are not worth smelting; the following, however, are:--

  _d_, the _schiefer kopf_, the main copper-schist, 2 inches thick.
  _e_, a layer called _lochen_, one inch thick.

14. The wall of sandstone, resting upon a porphyry.

[Illustration: 735]

_Fig._ 735. is a section of the mines of Kiegelsdorf in Hessia,
presenting--

1. Vegetable mould.

2. Limestone distinctly stratified, frequently of a yellowish colour,
called _lagerhafter kalkstein_.

3. Clay, sometimes red, sometimes blue, sometimes a mixture of red,
blue, and yellow.

4. The cellular limestone (_rauhkalk_). This rock differs both in nature
and position from the rock of the same name at Mansfeldt.

5. Clay, usually red, containing veins of white gypsum, and fine
crystals of selenite.

6. Massive gypsum of recent formation.

7. Fetid limestone, compact and blackish gray, or cellular and yellowish
gray.

8. Pulverulent limestone, with solid fragments interspersed.

9. Compact marl-limestone, or _zechstein_, which changes from a brownish
colour above to a blackish schist below, as it comes nearer the cupreous
schist, which seems to form a part of it.

10. Cupreous schist (_kuperschiefer_), of which the bottom portion, from
4 to 6 inches thick, is that selected for metallurgic operations.
Beneath it, is found the usual wall or bed of sandstone. A vein of
cobalt ore _a_, which is rich only in the grayish-white sandstone
(_weisse liegende_), traverses and deranges all the beds wherever it
comes.

_Of working mines by fire._--The celebrated mine worked since the tenth
century in the mountain called _Rammelsberg_, in the Hartz, to the south
of Goslar, presents a stratified mass of ores, among the beds of the
rock which constitute that mountain. The mineral deposit is situated in
the earth, like an enormous inverted wedge, so that its thickness
(power), inconsiderable near the surface of the ground, increases as it
descends. At about 100 yards from its outcrop, reckoning in the
direction of the slope of the deposit, it is divided into two portions
or branches, which are separated from each other, throughout the whole
known depth, by a mass of very hard clay slate, which passes into flinty
slate. The substances composing the workable mass are copper and iron
pyrites with sulphuret of lead (galena), accompanied by quartz,
carbonate of lime, compact sulphate of baryta, and sometimes gray copper
ore, sulphuret of zinc, and arsenical pyrites. The ores of lead and
copper contain silver and gold, but in small proportion, particularly as
to the last.

[Illustration: 736]

A mine so ancient as that of Rammelsberg, and which was formerly divided
among several adventurous companies, cannot fail to present a great many
shafts and excavations; but out of the 15 pits, only two are employed
for the present workings; namely, those marked A B and E F, in _fig._
736., by which the whole extraction and drainage are executed.--The
general system of exploitation by fire, as practised in this mine,
consists of the following operations:--

1. An advance is made towards the deposits of ore, successively at
different levels, by transverse galleries which proceed from the shaft
of extraction, and terminate at the wall of the stratiform mass.

2. There is formed in the level to be worked, large vaults in the heart
of the ore, by means of fire, as we shall presently describe.

3. The floor of these vaults is raised up by means of terraces formed
from the rubbish, in proportion as the roof is scooped out.

4. The ores detached by the fire from their bed, are picked and
gathered; sometimes the larger blocks are blasted with gunpowder.

5. Lastly, the ores thus obtained are wheeled towards the shaft of
extraction, and turned out to the day.

Let us now see how the excavation by fire is practised; and in that
view, let us consider the state of the workings in the mines of
Rammelsberg in 1809. We may remark in _fig._ 736. the regularity of the
vaults previously scooped out above the level B C, and the other vaults
which are in full activity of operation. It is, therefore, towards the
lower levels that the new workings must be directed. For this purpose,
the transverse gallery being already completed, there is prepared on the
first of these floors a vault of exploitation at _b_, which eventually
is to become similar to those of the superior levels. At the same time,
there is commenced at the starting point below it, reached by a small
well dug in the line of the mineral deposit, a transverse gallery in the
rock, by means of blasting with gunpowder. The rock is also attacked at
the starting-point by a similar _cut_, which advances to meet the first
perforation. In this way, whenever the vaults of the level C are
exhausted of ore and terraced up with rubbish, those of the level
beneath it will be in full activity.

Others will then be prepared at a lower level; and the exploitation may
afterwards be driven below this level by pursuing the same plan, by
which the actual depth of excavation has been gained.

In workings by fire we must distinguish, 1. The case where it is
necessary to open a vault immediately from the floor; 2. The case where
the vault having already a certain elevation, it is necessary to
heighten its roof. In the former case, the wall or floor of the mineral
deposit is first penetrated by blasting with gunpowder. As soon as this
penetration is effected over a certain length, parallel to the direction
of the future vault, as happens at _b_, there is arranged on the bottom
a horizontal layer of billets of firwood, over which other billets are
piled in nearly a vertical position, which rest upon the ore, so that
the flame in its expansion comes to play against the mineral mass to be
detached. When after some similar operations, the flame of the pile can
no longer reach the ore of the roof on account of its height, a small
terrace of rubbish must be raised on the floor of the deposit; and over
this terrace, a new pile of faggots is to be heaped up as above
described. The ancient miners committed the fault of constantly placing
such terraces close to the roof, and consequently arranging the faggots
against this portion of the ore, so that the flame circulated from the
roof down to the floor. The result of such procedure was the weakening
of the roof, and the loss of much of the ore which could not be
extracted from so unstable a fabric; and besides, much more wood was
burned than at the present day, because the action of the flame was
dissipated in part against the whole mass of the roof, instead of being
concentred on the portion of the ore which it was desired to dislodge.
Now, the flame is usually made to circulate from the floor to the roof,
in commencing a new vault.

When the vault has already a certain height, care is always taken that
between the roof of the vault and the rubbish on which the pile is
arranged, no more than two yards of space should intervene, in order
that the flame may embrace equally the whole concavity of the vault, and
produce an uniform effect on all its parts. Here, the pile is formed of
horizontal beds, disposed crosswise above one another, and presents four
free vertical faces, whence it has been called a _chest_ by the miners.

It is usually on Saturday that the fire is applied to all the piles of
faggots distributed through the course of the week. Those in the upper
floors of exploitation are first burned, in order that the inferior
piles may not obstruct by their vitiated air, the combustion of the
former. Thus, at 4 o’clock in the morning, the fires are kindled in the
upper ranges; from pile to pile, the fireman and his assistant descend
towards the lower floors, which occupies them till 3 o’clock in the
afternoon. Vainly should we endeavour to describe the majestic and
terrific spectacle which the fire presents, as it unfolds its wings
under its metallic vaults, soon filled with vast volumes of smoke and
flame. Let us mark the useful effect which it produces.

When the flame has beat for a few instants on the beds of ore, a strong
odour of sulphur, and sometimes of arsenic is perceived; and soon
thereafter loud detonations are heard in the vaults. Suddenly the flame
is seen to assume a blue colour, or even a white; and at this period,
after a slight explosion, flakes of the ore, of greater or less
magnitude, usually fall down on the fire, but the chief portion of the
heated mineral still remains fixed to the vault. The ores pass now into
a shattered and divided condition, which allows them afterwards to be
detached by long forks of iron. In this manner the fire, volatilizing
entirely some principles, such as sulphur, zinc, arsenic, and water,
changing the aggregation of the constituent parts of the ore, and
causing fissures by their unequal expansibilities, facilitates the
excavation of such materials as resist by their tenacity the action of
gunpowder.

The combustion goes on without any person entering the mine from
Saturday evening till Monday morning, on which day, the fireman and his
assistants proceed to extinguish the remains of the bonfires. On Monday
also some piles are constructed in the parts where the effect of the
former ones has been incomplete; and they are kindled after the workmen
have quitted the mine. On Tuesday all hands are employed in detaching
the ores, in sorting them, taking them out, and preparing new piles
against the next Saturday.

The labour of a week consists for every man of five posts during the
day, each of 8 hours, and of one post of four hours for Saturday.
Moreover, an extra allowance is made to such workmen as employ
themselves some posts during the night.

The labour of one compartment or _atelier_ of the mine consists
therefore in arranging the faggots, in detaching the ore which has
already experienced the action of the fire, in breaking the blocks
obtained, in separating the ore from the _débris_ of the pile, and
whenever it may be practicable or useful, in boring holes for blasting
with gunpowder. The heat is so great in this kind of mine, that the men
are obliged to work in it without clothing.

We have already remarked, that besides the working by fire, which is
chiefly used here, recourse is sometimes had to blasting by gunpowder.
This is done in order either to recover the bottom part or ground of the
vaults on which the fire can act but imperfectly, to clear away some
projections which would interfere with the effect of the pile, or lastly
to strip the surrounding rock from the mass of the ore, and thence to
obtain schist proper for the construction of the rubbish-terraces.

The blasting process is employed when the foremen of the workshop or
mine-chamber judge that a hole well placed may separate enough of ore to
pay the time, the repair of tools, and the gunpowder expended. But this
indemnification is rarely obtained. The following statement will give an
idea of the tenacity which the mineral deposit often presents.

In 1808, in a portion of the Rammelsberg mine, the ore, consisting of
extremely compact iron and copper pyrites, was attacked by a single man,
who bored a mining hole. After 11 posts of obstinate labour, occupying
altogether 88 hours, the workman, being vigilantly superintended, had
been able to advance the hole to a depth of no more than 4 inches; in
doing which he had rendered entirely unserviceable 126 punches or
borers, besides 26 others which had been re-tipped with steel, and 201
which had been sharpened; 6-1/4 pounds of oil had been consumed in
giving him light; and half a pound of gunpowder was required for
blasting the bore. It was found from a calculation made upon these facts
by the administration of mines, that every inch deep of this hole cost,
at their low price of labour, nearly a florin, value two shillings and
sixpence.

It is therefore evident that though the timber, of which the consumption
is prodigiously great, were much less abundant and dearer than it still
is at Rammelsberg, mining by fire would be preferable to every other
mode of exploitation. It is even certain, that on any supposition, the
employment of gunpowder would not be practicable for every part of the
mine; and if fuel came to fail, it would be requisite to renounce the
workings at Rammelsberg, although this mountain still contains a large
quantity of metals.

If in all mines the free circulation of air be an object of the highest
importance, we must perceive how indispensable it must be in every part
of a mine where the mode of exploitation maintains the temperature of
the air at 112° Fahr., when the workmen return into it after the
combustion of the piles, and in which besides it is necessary that this
combustion be effected with activity in their absence. But in
consequence of the extent and mutual ramifications of the workings, the
number of the shafts, galleries, and their differences of level, the
ventilation of the mine is in a manner spontaneously maintained. The
high temperature is peculiarly favourable to it. The aid of art consists
merely in placing some doors judiciously, which may be opened or shut at
pleasure, to carry on the circulation of the air.

In considering the Rammelsberg from its summit, which rises about 400
yards above the town of Goslar, we observe, first, beds of slaty
sandstone, which become the more horizontal the nearer they approach to
the surface. At about 160 yards below the top level there occurs, in the
bosom of the slaty graywacke, a powerful stratum of shells impasted in a
ferruginous sandstone. See D, _fig._ 730. In descending towards the face
of the ore, the parallel stratification of the clay-slate which forms
its walls and roof grows more and more manifest. Here the slate is
black, compact, and thinly foliated. The inclination of the different
beds of rock is indicated at B. The substance of the workable mass is
copper and iron pyrites, along with sulphuret of lead, accompanied by
quartz, carbonate of lime, compact sulphate of baryta, and occasionally
gray copper (_fahlerz_), sulphuret of zinc, and arsenical pyrites.

The ores are argentiferous and auriferous, but very slightly so,
especially as to the gold. It is the ores of lead and copper which
contain the silver, and in the latter the gold is found, but without its
being well ascertained in what mineral it is deposited. Sometimes the
copper occurs in the native state, or as copper of cementation.
Beautiful crystals of sulphate of lime are found in the old workings.

[Illustration: 737]

In _figs._ 736. 737., A B is the shaft of extraction, called
the _Kahnenkuhler_; N is the ventilation shaft, called
_Breitlingerwetterschacht_; P is the extraction shaft, called
_Innier-schacht_.

E F, is a new extraction-shaft, called _Neuer treibschacht_, by which
also the water is pumped up; by A B, and E F, the whole extraction and
draining are carried on. The ores are raised in these shafts to the
level of the waggon-gallery (_galerie de roulage_) _i_, by the whims
_l_, _q_, provided with ropes and buckets. 1, 2, 3, 4, _fig._ 736.,
represent the positions of four water-wheels for working the whims; the
first two being employed in extracting the ores, the last two in
draining. The driving stream is led to the wheel 1, along the drift _l_;
whence it falls in succession upon the wheels 2, 3, 4. The general
system of working consists of the following operation;--

1. The bed of ore is got at by the transverse galleries, _m_, _n_, _o_,
_q_, _r_, _s_, which branch off from the extraction shaft, and terminate
at the wall of the main bed;

2. Great vaults are scooped out at the level of the workings, by means
of fire;

3. The roofs of these vaults are progressively propped with mounds of
rubbish;

4. The ores thus detached, or by blasting with gunpowder, are then
collected;

5. Lastly, they are wheeled out to the day; and washed near Z.

COMPARATIVE TABLE of celebrated MINES in EUROPE and AMERICA. By F. Burr,
Esq. (_Quarterly Mining Review for July_, 1835, p. 60.)

  +--------+--------------+--------------+--------------+--------------+
  |        |CONSOLIDATED  |VETA GRANDE   |MINE OF       |MINE OF       |
  |        |AND UNITED    |MINES.        |VALENCIANA.   |HIMMELSFÜRST. |
  |        |MINES.        |              |              |              |
  |        +--------------+--------------+--------------+--------------+
  |        |(At present   |(At present   |(Richest of   |(Richest of   |
  |        |the richest   |the richest   |the Mexican   |the Saxon     |
  |        |mines in Corn-|mines in      |mines at the  |mines at the  |
  |        |wall.)        |Mexico.)      |beginning of  |beginning of  |
  |        |              |              |the present   |the present   |
  |        |              |              |century.)     |century.)     |
  |        |              |              |              |              |
  |Situa-  |Two miles east|Four miles    |One mile north|Two miles     |
  |tion    |of Redruth.   |north of      |of Guanaxuato.|south-east of |
  |        |              |Zacatecas.    |              |Freyberg.     |
  |        |              |              |              |              |
  |Eleva-  |Elevation of  |Elevation of  |Elevation of  |Elevation of  |
  |tion    |the surface a-|the surface a-|the surface a-|the surface a-|
  |        |bove the level|bove the level|bove the level|bove the level|
  |        |of the sea,   |of the sea,   |of the sea,   |of the sea,   |
  |        |from 200 to   |supposed to be|7,617 feet.   |1,346 feet.   |
  |        |300 ft.; depth|about 6000    |Elevation of  |Elevation of  |
  |        |of the bottom |feet. Eleva-  |the bottom of |the bottom of |
  |        |of the mine   |tion of the   |the mine above|the mine above|
  |        |below the     |bottom of the |the level of  |the level of  |
  |        |level of the  |mine above the|the sea, 5,730|the sea, 263  |
  |        |sea, about    |level of the  |feet.         |feet.         |
  |        |1,370 feet.   |sea, probably |              |              |
  |        |              |near 5,000    |              |              |
  |        |              |feet.         |              |              |
  |        |              |              |              |              |
  |Nature  |The _Veta_    |The rock pre- |Primary clay  |Transition    |
  |of the  |_Madre_ of    |vailing in the|slate resting |clay slate,   |
  |rock    |Guanaxuato,   |neighbourhood |immediately on|alternating   |
  |        |upon which    |of Freyberg,  |granite, a    |with dolomite,|
  |        |this mine is  |in which this |short distance|and occasion- |
  |        |worked, tra-  |and most of   |westward of   |ally with     |
  |        |verses both   |the other     |the mines. The|greywacke.    |
  |        |clay slate and|mines are     |clay slate is |This clay     |
  |        |porphyry, but |situate, is a |intersected by|slate is some-|
  |        |it is most    |formation of  |numerous chan-|times decom-  |
  |        |productive in |primary       |nels of por-  |posed; it     |
  |        |the former    |gneiss.       |phyry, which  |rests on sye- |
  |        |rock. The clay|              |have nearly   |nitic rocks,  |
  |        |slate is con- |              |the same di-  |and is in some|
  |        |sidered by    |              |rection as the|places covered|
  |        |Humboldt to   |              |mineral veins,|with porphyry.|
  |        |belong to the |              |and are often |              |
  |        |transition    |              |of consider-  |              |
  |        |class, but    |              |able width.   |              |
  |        |situate near  |              |The porphyry  |              |
  |        |the limits of |              |sometimes     |              |
  |        |primary forma-|              |appears also  |              |
  |        |tions. This   |              |to form large |              |
  |        |rock in depth,|              |irregular mas-|              |
  |        |passes into   |              |ses in the    |              |
  |        |chlorite      |              |clay slate.   |              |
  |        |slate, and    |              |Both rocks are|              |
  |        |talc slate. It|              |traversed by  |              |
  |        |contains sub- |              |veins of      |              |
  |        |ordinate beds |              |quartz and    |              |
  |        |of syenite,   |              |clay inter-   |              |
  |        |hornblende    |              |secting the   |              |
  |        |slate, and    |              |metalliferous |              |
  |        |serpentine.   |              |veins.        |              |
  |        |The porphyry  |              |              |              |
  |        |rests upon the|              |              |              |
  |        |clay slate,   |              |              |              |
  |        |and is con-   |              |              |              |
  |        |formable to   |              |              |              |
  |        |it, both in   |              |              |              |
  |        |direction and |              |              |              |
  |        |stratifica-   |              |              |              |
  |        |tion.         |              |              |              |
  |        |              |              |              |              |
  |Nature  |In the con-   |One principal |One Veta (the |There are five|
  |of the  |solidated     |vein (the     |_Veta Madre_) |veins worked  |
  |metalli-|mines, the    |_Veta Grande_)|which is often|in this mine. |
  |ferous  |eight follow- |which is gen- |separated into|The principal |
  |deposits|ing lodes are |erally sepa-  |three         |vein (_Teich- |
  |        |extensively   |rated into    |branches, ex- |flache_) is   |
  |        |worked:--Wheal|three         |tending from  |from one foot |
  |        |Fortune lode, |branches, and |130 to 160    |six inches, to|
  |        |Cusvea lode,  |sometimes into|feet in width.|three feet in |
  |        |Deeble’s lode,|four. When    |When not rami-|width, the    |
  |        |Old lode,     |ramified, the |fied, its     |others are    |
  |        |Taylor’s lode,|width extends |width varies  |from six to 12|
  |        |Tregonning’s  |to 60 or 70   |from 20 or 30 |inches wide.  |
  |        |lode, Martin’s|feet; when    |to 60 or 70   |The direction |
  |        |lode, and     |united, it    |feet, but is  |of this vein, |
  |        |Glover’s lode.|varies from 8 |more commonly |is nearly     |
  |        |In the united |or 10 to 20 or|from 40 to 50 |north and     |
  |        |mines, the    |30 feet. The  |feet. The di- |south, its un-|
  |        |principal     |branches are  |rection of the|derlie is     |
  |        |workings are  |generally a-  |vein, is      |west, and a-  |
  |        |upon the Old  |bout 10 or 12 |north-west and|bout three    |
  |        |lode, and a-  |feet wide, and|south-east;   |feet per fath-|
  |        |bout five or  |the upper one |its underlie  |om. Some of   |
  |        |six others are|is most pro-  |is south, and |the other     |
  |        |more or less  |ductive.      |about five or |veins inter-  |
  |        |productive.   |The direction |six feet per  |sect it.      |
  |        |Numerous smal-|of the Veta   |fathom.       |              |
  |        |ler lodes or  |Grande, is    |              |              |
  |        |“branches” oc-|from 30 to 40 |              |              |
  |        |cur also in   |degrees south |              |              |
  |        |both mines.   |of east, and  |              |              |
  |        |The principal |north of west,|              |              |
  |        |lodes are from|and its under-|              |              |
  |        |2 or 3, to 7  |lie, from two |              |              |
  |        |or 8 feet     |to three feet |              |              |
  |        |wide; the     |per fathom    |              |              |
  |        |“branches” are|south. Other  |              |              |
  |        |generally 12  |veins of less |              |              |
  |        |or 18 inches  |size, occur in|              |              |
  |        |wide. The di- |the neighbour-|              |              |
  |        |rection of the|hood of the   |              |              |
  |        |lodes varies  |Veta Grande,  |              |              |
  |        |from nearly   |which cross it|              |              |
  |        |east and west |at an acute   |              |              |
  |        |to about 20   |angle. One of |              |              |
  |        |degrees north |these appears |              |              |
  |        |of east and   |to heave the  |              |              |
  |        |south of west.|vein for about|              |              |
  |        |The underlie  |700 feet, be- |              |              |
  |        |of the princi-|ing the most  |              |              |
  |        |pal lodes, is |remarkable de-|              |              |
  |        |from 2 to 3   |rangement of  |              |              |
  |        |feet per fath-|the kind on   |              |              |
  |        |om north, that|record.       |              |              |
  |        |of the smaller|              |              |              |
  |        |ones about the|              |              |              |
  |        |same south.   |              |              |              |
  |        |              |              |              |              |
  |Ores    |Chiefly copper|Chiefly red   |Sulphuret of  |Argentiferous |
  |        |ore, occasion-||silver, na-  |silver, native|sulphuret of  |
  |        |ally native   |tive silver,  |silver, pris- |lead, native  |
  |        |copper, blue  |sulphuret of  |matic black   |silver, sul-  |
  |        |and green car-|silver, and   |silver, red   |phuret of     |
  |        |bonate of     |argentiferous |silver, native|silver, red   |
  |        |copper. Tin,  |pyrites.      |gold, argen-  |silver.       |
  |        |or oxide of   |              |tiferous      |              |
  |        |tin, also oc- |              |galena.       |              |
  |        |curs, but not |              |              |              |
  |        |in very great |              |              |              |
  |        |abundance.    |              |              |              |
  |        |              |              |              |              |
  |Produce |9-1/4 per     |3-1/2 oz. per |Four ounces of|Six to seven  |
  |of the  |cent. of fine |quintal.      |silver per    |ounces of sil-|
  |ores    |copper; aver- |              |quintal of 100|ver per quin- |
  |        |age produce in|              |lbs., equiva- |tal of 100    |
  |        |100 parts of  |              |lent to 2-1/2 |lbs. Equiva-  |
  |        |ore.          |              |parts of metal|lent to from  |
  |        |              |              |in 1,000 of   |3-3/4 to 4-1/2|
  |        |              |              |ore, or 1/4   |parts of metal|
  |        |              |              |per cent.     |in 1,000 of   |
  |        |              |              |              |ore, or from  |
  |        |              |              |              |3-8ths to     |
  |        |              |              |              |nearly 1/2 per|
  |        |              |              |              |cent.         |
  |        |              |              |              |              |
  |Vein-   |Chiefly       |Chiefly       |Quartz, ame-  |Quartz, pearl-|
  |stone   |quartz, of    |quartz, occa- |thyst, carbon-|spar, and cal-|
  |        |which many    |sionally ame- |ate of lime,  |careous spar. |
  |        |varieties oc- |thyst, carbon-|pearlspar, and|              |
  |        |cur.          |ate of lime,  |hornstone.    |              |
  |        |              |and sulphate  |              |              |
  |        |              |of barytes.   |              |              |
  |        |              |              |              |              |
  |Mineral |The ores are  |The ores are  |The ores are  |The ores are  |
  |sub-    |generally     |generally     |accompanied by|accompanied by|
  |stances |accompanied by|accompanied by|blende,       |blende,       |
  |        |“gossan”[34]  |blende, sul-  |spathose iron,|spathose iron,|
  |        |in the backs  |phuret of     |copper and    |and a little  |
  |        |of the lodes, |antimony, and |iron pyrites. |iron and ar-  |
  |        |by blende, and|iron pyrites. |              |senical py-   |
  |        |by iron, and  |              |              |rites.        |
  |        |arsenical     |              |              |              |
  |        |pyrites in    |              |              |              |
  |        |depth.        |              |              |              |
  |        |              |              |              |              |
  |Depth of|_Woolf’s en-_ |_Tiro Gener-_ |_Tiro Gener-  |_Franken-     |
  |the     |_gine-shaft_, |_al_, 182     |al_, 310 fath-|schacht_, 180 |
  |princi- |248 fathoms;  |fathoms;      |oms.          |fathoms.      |
  |pal     |Pearce’s _en-_|_Gallega_     |              |              |
  |shafts  |_gine-shaft_, |shaft, 138    |              |              |
  |        |275 fathoms.  |fathoms.      |              |              |
  |        |Some of the   |              |              |              |
  |        |other engine  |              |              |              |
  |        |shafts are    |              |              |              |
  |        |scarcely in-  |              |              |              |
  |        |ferior in     |              |              |              |
  |        |depth.        |              |              |              |
  |        |              |              |              |              |
  |Depth of|At Woolf’s    |There is no   |There is no   |The adit at   |
  |adit at |engine-shaft, |adit to this  |adit to this  |the shaft     |
  |the     |13 fathoms.   |mine.         |mine.         |called Fran-  |
  |princi- |The average   |              |              |kenschacht is |
  |pal     |depth of the  |              |              |47 fathoms in |
  |shafts  |adit at the   |              |              |depth.        |
  |        |other engine- |              |              |              |
  |        |shafts is a-  |              |              |              |
  |        |bout 30 or 40 |              |              |              |
  |        |fathoms.      |              |              |              |
  |        |              |              |              |              |
  |Quantity|Varies from   |About 80 gal- |The Valenciana|50 gallons per|
  |of water|2,000 to 3,000|lons per min- |was a dry mine|minute.       |
  |        |gallons per   |ute.          |from its com- |              |
  |        |minute.       |              |mencement in  |              |
  |        |              |              |1760 to 1780, |              |
  |        |              |              |when it first |              |
  |        |              |              |became        |              |
  |        |              |              |troubled with |              |
  |        |              |              |water, in con-|              |
  |        |              |              |sequence of   |              |
  |        |              |              |some of the   |              |
  |        |              |              |workings being|              |
  |        |              |              |inadvertently |              |
  |        |              |              |communicated  |              |
  |        |              |              |with the ad-  |              |
  |        |              |              |joining mine  |              |
  |        |              |              |of Tepeyac;   |              |
  |        |              |              |which, al-    |              |
  |        |              |              |though upon   |              |
  |        |              |              |the same vein,|              |
  |        |              |              |was extremely |              |
  |        |              |              |wet. The quan-|              |
  |        |              |              |tity of water |              |
  |        |              |              |raised during |              |
  |        |              |              |the late work-|              |
  |        |              |              |ing appears to|              |
  |        |              |              |have been a-  |              |
  |        |              |              |bout 110 gal- |              |
  |        |              |              |lons per min- |              |
  |        |              |              |ute, but the  |              |
  |        |              |              |regular influx|              |
  |        |              |              |was much less.|              |
  |        |              |              |              |              |
  |Height  |About 230     |On an average |310 fathoms.  |133 fathoms.  |
  |to which|fathoms at the|about 150     |              |              |
  |the     |consolidated  |fathoms.      |              |              |
  |water is|mines, at the |              |              |              |
  |raised  |united mines, |              |              |              |
  |        |about 110     |              |              |              |
  |        |fathoms.      |              |              |              |
  |        |              |              |              |              |
  |Power   |9 steam-en-   |Usually 10    |A steam-engine|Two water-    |
  |employed|gines; 3 of   |malacates.[b] |of 30-inch    |wheels, each  |
  |in      |90-inch cylin-|              |cylinder, and |42 feet in    |
  |drainage|der, 3 of 85, |              |7 malacates.  |diameter.     |
  |        |1 of 80, and 2|              |              |              |
  |        |of 65. A water|              |              |              |
  |        |wheel, 48 feet|              |              |              |
  |        |in diameter.  |              |              |              |
  |        |              |              |              |              |
  |Probable|1,500 con-    |32 horses con-|65 horses con-|16 horses con-|
  |equiva- |stantly at    |stantly work- |stantly at    |stantly at    |
  |lent in |work, or a    |ing, or a     |work, or a    |work or a     |
  |actual  |total number  |total number  |total number  |total number  |
  |horse-  |of above      |of about 100  |of about 200. |of about 50.  |
  |power   |4,500.        |horses.[c]    |              |[d]           |
  |        |              |              |              |              |
  |Average |12,700_l._    |20,000_l._ per|About         |Cannot be as- |
  |annual  |taking the    |annum.[c]     |40,000_l._,   |certained, but|
  |expense |average of the|              |per annum.[d] |evidently very|
  |in      |last ten      |              |              |small.[d]     |
  |drainage|years.[a]     |              |              |              |
  |        |              |              |              |              |
  |Quantity|16,400 tons of|21,380 tons of|32,500 tons of|630 tons of   |
  |of ore  |copper ore, a |silver ore.[c]|silver ore.[d]|silver ore.[d]|
  |annually|few tons of   |              |              |              |
  |produced|tin ore.[a]   |              |              |              |
  |        |              |              |              |              |
  |Produce |1,517 tons of |153,000 lbs.  |221,900 lbs.  |6,160 lbs.    |
  |in metal|fine copper, a|troy of sil-  |troy silver.  |troy of sil-  |
  |        |little tin.[a]|ver.[c]       |[d]           |ver.[d]       |
  |        |              |              |              |              |
  |Total   |119,800_l._[a]|423,400_l._   |About         |About         |
  |returns,|              |per annum.[c] |600,000_l._[d]|18,000_l._[d] |
  |or value|              |              |              |              |
  |of the  |              |              |              |              |
  |above   |              |              |              |              |
  |        |              |              |              |              |
  |Total   |93,500_l._ ex-|252,170_l._   |197,900_l._   |9,500_l._ per |
  |costs of|clusive of    |per annum.[c] |per annum.[d] |annum.[d]     |
  |the mine|lord’s dues;  |              |              |              |
  |        |98,600_l._ in-|              |              |              |
  |        |cluding lord’s|              |              |              |
  |        |dues.[a]      |              |              |              |
  |        |              |              |              |              |
  |Clear   |21,000_l._ per|171,240_l._   |118,750_l._   |3,560_l._ per |
  |profit  |annum.[a]     |per annum.[c] |per annum.[d] |annum.[d]     |
  |to the  |              |              |              |              |
  |proprie-|              |              |              |              |
  |tors    |              |              |              |              |
  |        |              |              |              |              |
  |Amount  |75,000_l._[a] |130,000_l._[c]|Cannot be as- |Cannot be as- |
  |of      |              |              |certained, but|certained, but|
  |capital |              |              |known to have |probably very |
  |invested|              |              |been very     |small.[d]     |
  |        |              |              |small.[d]     |              |
  |        |              |              |              |              |
  |Interest|280 per cent. |Nearly 700 per|Not known, but|Not known, but|
  |on      |after paying  |cent. after   |certainly many|probably very |
  |capital |back the orig-|paying back   |hundred per   |high.[d]      |
  |invested|inal capital. |the original  |cent.[d]      |              |
  |        |[a]           |capital.[c]   |              |              |
  |        |              |              |              |              |
  |Propor- |Costs exclu-  |About 59-1/2  |Costs 60 per  |Costs 73 per  |
  |tion of |sive of lord’s|per cent.     |cent. In the  |cent.[d]      |
  |costs to|dues, 78 per  |              |nine years    |              |
  |returns |cent.[a]      |              |following, the|              |
  |        |              |              |proportion was|              |
  |        |              |              |80 per cent., |              |
  |        |              |              |at the end of |              |
  |        |              |              |that time the |              |
  |        |              |              |working of the|              |
  |        |              |              |mine was      |              |
  |        |              |              |stopped by the|              |
  |        |              |              |revolution, in|              |
  |        |              |              |the year 1809.|              |
  |        |              |              |[d]           |              |
  |        |              |              |              |              |
  |Number  |About 2,500   |About 900, of |3,100 Indians |700 miners of |
  |of men  |persons, of   |whom nearly   |and Mestizoes,|whom 550 are  |
  |employed|whom about    |600 are em-   |of whom 1,800 |employed under|
  |        |1,450 are em- |ployed under  |are employed  |ground.       |
  |        |ployed under  |ground.       |under ground. |              |
  |        |ground.       |              |              |              |
  |        |              |              |              |              |
  |Wages of|Probably about|About 8 or 9  |From 4 to 5   |About 1_s._   |
  |the     |3 shillings on|shillings per |shillings.    |6_d._ per day.|
  |mines   |an average.   |day.          |              |              |
  |per day |              |              |              |              |
  |        |              |              |              |              |
  |Quantity|              |              |1,420 cwt.;   |240 cwt.;     |
  |and ex- |              |              |value         |value         |
  |pense of|              |              |15,830_l._    |1,070_l._     |
  |powder  |              |              |              |              |
  |        |              |              |              |              |
  |Manner  |Sold to the   |Chiefly re-   |Sold to the   |Delivered to  |
  |in which|smelting com- |duced by the  |Rescatadores, |the government|
  |the ores|panies, and   |company at the|and reduced by|reduction     |
  |are dis-|smelted by    |hacienda of   |smelting and  |works in the  |
  |posed of|them at Swan- |Sanceda, by   |amalgamation  |neighbourhood |
  |        |sea, in South |smelting and  |at haciendas, |of Freyberg,  |
  |        |Wales.        |amalgamation. |in the neigh- |where they are|
  |        |              |              |bourhood of   |partly        |
  |        |              |              |Guanaxuato.   |smelted, and  |
  |        |              |              |              |partly amal-  |
  |        |              |              |              |gamated.      |
  +--------+--------------+--------------+--------------+--------------+

  [a] Average of the last Ten Years.
  [b] Malacate; a horse whim.
  [c] Average of the last Six Years.
  [d] Average year at the end of the Eighteenth Century.

  [34] Gossan, or Gozzan; oxide of iron and quartz.

VENTILATION OF MINES.

When men penetrate by narrow passages into the interior of the earth,
their respiration, joined to the combustion of candle and gunpowder, are
not long of vitiating the air. The decomposition of wood contributes to
the same effect, as also the mineral bed itself, especially in coal
mines, by the carburetted hydrogen and carbonic acid evolved, and from
the absorption of oxygen by pyrites. In many cases, arsenical and
mercurial vapours are disengaged. Hence the necessity of maintaining in
subterranean cavities a continual circulation of air, which may renew
the atmosphere round the miners. The whole of the means employed to
produce this effect, constitutes what is called the _ventilation of
mines_.

These means are divided into _natural_ and _artificial_. The _natural
means_ are the currents produced by the difference of density between
the air of mines and the external air; the _artificial_ are
air-exhausters or condensers, fires, &c.

The temperature of the air of the subterranean workings surpasses the
mean temperature of the place in which the mine is opened. Hence it is
lighter in winter, but in summer often heavier than the air of the
atmosphere. For this reason, when the mine presents two openings at
different levels, the air naturally flows out by the most elevated in
winter, and by the lowest in summer. We may take advantage of this
circumstance, to lead the air into the bottom of even a very long
gallery, opening into the side of the mountain, by piercing a shaft into
its roof at some distance from the entrance, and dividing the gallery by
a horizontal floor into two parts, which have no mutual communication,
except at the furthest extremity--the upper part communicating with the
shaft, and the under with the mouth of the gallery. If the two
compartments have different dimensions, the air in the smaller sooner
comes into an equilibrium of temperature with the rock; and the
difference of temperature of the two compartments is sufficient to
produce a current. If a streamlet of water flows through this gallery,
it facilitates the flow of the air along the lower compartment. If a
mine has several openings situated on the same level, it rarely happens
but some peculiar circumstance destroys, during the colds of winter and
the heats of summer, the equilibrium of the air. But in spring and
autumn, when the external air is nearly of the same temperature with
that of the mines, the above-named causes are almost always too feeble
to excite an issuing current. This effect is, however, frequently
obtained by raising over one of the shafts a chimney 20 or 30 yards
high, which alone produces the effect of an opening at a different
level. It has been remarked that stormy weather usually deranges every
system of ventilation. See PITCOAL and VENTILATION.


MINIUM. (Eng. and Fr., _Red lead_; _Mennige_, Germ.) This pigment is a
peculiar oxide of lead, consisting of two atoms of the protoxide and one
of the peroxide; but, as found in commerce, it always contains a little
extra protoxide, or yellow massicot. It is prepared by calcining lead
upon a reverberatory hearth with a slow fire, and frequent renewal of
the surface with a rake, till it becomes an oxide, taking care not to
fuse it. The calcined mass is triturated into a fine powder in a paint
mill, where it is elutriated with a stream of water, to carry off the
finely levigated particles, and to deposit them afterwards in tanks. The
powder thus obtained being dried, is called massicot. It is converted
into minium, by being put in quantities of about 50 pounds into iron
trays, 1 foot square, and 4 or 5 inches deep. These are piled up upon
the reverberatory hearth, and exposed during the night, for economy of
fuel, to the residuary heat of the furnace, whereby the massicot absorbs
more oxygen, and becomes partially red lead. This, after being stirred
about, and subjected to a similar low calcining heat once and again,
will be found to form a marketable red lead.

The best minium, however, called _orange mine_, is made by the slow
calcination of good white lead (carbonate) in iron trays. If the lead
contains either iron or copper, it affords a minium which cannot be
employed with advantage in the manufacture of flint-glass, for pottery
glazes, or for house-painting.

Dumas found several samples of red lead which he examined to consist of
the chemical sesquioxide and the protoxide, in proportions varying from
50 of the former and 50 of the latter, to 95·3 of the former and 4·7 of
the latter. The more oxygen gas it gives out when heated, the better it
is, generally speaking. See NAPLES YELLOW.


MINT. (_Monnaie_, Fr.; _Münze_, Germ.) The chief use of gold and silver
is to serve for the medium of exchange in the sale and purchase of
commodities, a function for which they are pre-eminently fitted by their
scarcity, by being unalterable by common agents, and condensing a great
value in a small volume. It would be very inconvenient in general to
barter objects of consumption against each other, because their carriage
would be expensive, and their qualities, in many cases, easily injured
by external agents, &c. Gold is exempt from spontaneous change, and
little costly in conveyance. Mankind at a very early period recognised
how much easier it was to exchange a certain weight of gold or silver
for objects of commerce, than to barter these objects themselves; and
thenceforth all agreed to pay for their purchases in bars or ingots of
these precious metals. But as their intrinsic value depends upon their
purity, it became necessary to stamp on these bars their standard
quality and their weight.

The inconvenience of using ingots in general trade, on account of the
difficulty of defining fractional values, has determined governments to
coin pieces of money, that is, quantities of metal whose weight and
standard were made known and guaranteed by the effigies of the prince.
It is true, indeed, that kings have become frequently coiners of base
money, by altering the weight and purity of the pieces apparently
guaranteed by their impress. By such reductions modern coins represent
less of the precious metal than they did long ago. The _ordonnance_ of
755, for the coining of _sous_ in France, proves that there was then as
much fine silver in a single _sous_, as there is now in a piece of 5
francs. During the last two centuries, indeed, silver coins have been
diminished two thirds in weight.

But since knowledge has become more generally diffused, it has been
shown that these frauds are equally injurious to the prince and to
public faith. A sovereign may, it is true, declare by a decree that a
shilling-piece is to be held worth five; but let us consider the
consequences of this decree. All the individuals who have rents or
capital sums to receive, will be ruined, by getting in metallic value
only one-fifth of what is due to them; for although the _nominal_ value
should be the same as what they are entitled to, the intrinsic value
would be but a fifth of the former; so that when they go to purchase the
necessaries or comforts of life, the dealer who sells them will at once
raise their price five-fold. Each article of merchandise would thus
acquire a nominal price 5 times greater; and he who had received payment
of a debt in that money, could not with it procure more than one-fifth
of the goods he could have previously commanded. That fraudulent law
would, therefore, favour the debtors at the expense of the creditors;
and as the state is commonly a great debtor, especially when it has
recourse to the depreciation of the currency, it is obvious, that
however illicit the gain which it makes, it still does gain; and this is
the reason why princes have so often tampered with the mint. But let us
examine the other consequences of this decree.

If the sovereign is a debtor, he is also a creditor and consumer, and
even the most considerable of any. The taxes which he imposes are paid
him in this deteriorated money, returned to him at its nominal value;
and the purveyors of his armies, his buildings, and his household, sell
him their commodities only at the actual market price. We may infer from
this simple development that the coin with which he pays for any object
has the same intrinsic value as the object; and that the name given to
the coin is of no consequence. The prince may call it a crown, a ducat,
or a rix-dollar at his pleasure; and he may assign any value to it that
his caprice may suggest, yet this will not affect its value; for this is
fixed beyond his control by the general nature of things. The prince
may, indeed, at the outset, have profited by defrauding his creditors,
and by authorizing each debtor to imitate him, but he will soon lose
whatever he may have gained; and he will thus learn to his cost that it
was bad policy to sacrifice his character by giving an example of a
fraud so truly unprofitable in the issue. Moreover, he will lose still
as much in the following years, because his treasury will receive only
one-fifth part of the taxes, unless he has quintupled the imposts. It
may be said, indeed, that he might do the one thing along with the
other. But every one knows that this power is neither generally
permitted to princes, nor if it were, could it be safely exercised.
Serious political crises would combine to endanger the stability of the
government; which besides, as the main consumer in the nation, must lose
always as much as it seems to gain.

It is therefore manifest that the alteration of the standard and weight
of the coinage is at once a crime and a ruinous action for the sovereign
power to commit; and hence such disastrous measures have been long
abandoned in all well-regulated states. A gold sovereign is
intrinsically worth 20 shillings minus the cost of coinage; for were it
worth more, all our sovereign pieces would be exported or melted down,
to obtain the difference of value, however trifling it might be; and
were it worth less, it would be the source of loss similar to what the
state occasions when it depreciates the coin.

To comprehend the true value of a coin, we must regard this piece as an
article of merchandise, whose value depends, as that of every thing
else, on its usefulness, the esteem in which it is held, and the demand
for it in the market. Grain increases in value when there are few
sellers and many buyers; gold and silver are in the same predicament.
The value of these metals is much augmented, indeed, by the universal
currency they obtain when struck into money; a value additional to what
they possess as objects of the arts. This value of the precious metals
changes with time and place, like that of every merchandise; their
abundance, since the discovery of America, has greatly lowered their
value; that is, with the same weight of metal, we cannot at the present
day purchase the same quantity of corn, land, wool, &c. as formerly. In
the countries where silver abounds, this metal has less value, or, in
other terms, commodities are dearer. Hence the metal tends to resume its
equilibrium in flowing into those places where it is rarer; which means,
that the consumer prefers purchasing his commodities there rather than
in another place, if he can easily transport them to where they are
dearer.

It was formerly believed that a country is rich when it has a great deal
of gold and silver; but this popular illusion has passed away. Spain has
never been poorer than since the discovery of America, because its
national industry has been ruined, and the capitals merely passed
through its hands to spread over the rest of Europe, from which it was
obliged to import every thing that its want of home manufactures made it
necessary to procure from abroad. We may add to these, the prodigalities
of the court, which, supposing its wealth inexhaustible, tried to
corrupt all the ministers of the other powers, in furtherance of the
chimera of universal dominion. The richest state is that in which there
is most industry, whereby the inhabitants may procure every thing
indispensable to the conveniences and comforts of life. Gold as a useful
metal, and a medium of exchange, is undoubtedly very precious, and an
adequate quantity for these exchanges must be had; but as it is good for
very little besides, nay, as an excess is even hurtful, it soon begins
to fly of itself towards the places where it is more needed or less
common.

With regard to the relative value of gold and silver, several details
have already been given in our view of the mineral wealth of the globe.
Three centuries ago, an ounce of gold was worth at London or Paris 10
ounces of silver; now it may be exchanged for 15 ounces and a half.

The _par_ of two coins results from the comparison of their weight and
standard fineness. Let us take for an example the conversion of English
gold sovereigns worth 20 shillings or a pound sterling, in relation to
the French louis of 20 francs. The standard of the sovereign gold is
0·917, fine gold being 1000; its weight is 125·256 gr. English, or
7·980855 grammes; by multiplying this weight into its standard, we have
a product of 7·318444035; this is, in grammes, the quantity of pure gold
contained in the sovereign piece. The piece of 20 francs has a legal
standard of 0·9; and multiplying this number by the weight of the louis,
6·45161 grammes, we find that it contains 5·806449 of pure metal. We
then make this proportion:--

As 5·806449 : 20 francs ∷ 7·31844 : 25·2079 francs; or the value of the
English sovereign is nearly 25·21 francs, in French gold coin. A similar
calculation may be made for silver coins. The French rule for finding
the _par_ of a foreign gold coin, or its intrinsic value in francs, is
to multiply its weight by its standard or titre, and that product by
3-4/9. The par of foreign silver money, or its intrinsic value in
francs, is obtained by multiplying its weight in grammes by its standard
in thousand parts, and by 2/9. The French 5-franc piece has its standard
or titre at 0·9, and weighs 25 grammes.

The assaying of gold for coin and trinkets requires very delicate
management. The French take half a gramme at most (about 7-1/2 grains)
of gold, and fuse it with thrice its weight of silver, as already
described under ASSAY. The parting is the next operation. For this
purpose the button of gold and silver alloy is first hammered flat on a
piece of steel, and then made feebly red hot in burning charcoal or over
a lamp flame. After being thus annealed, the metal is passed through the
rolling press, till it be converted into a plate about 1/70 of an inch
thick. After annealing this riband, it is coiled into a spiral form,
introduced immediately into a small matrass of a pear shape, an assay
matrass, and about 500 grains of nitric acid, sp. grav. 1·185, are
poured over it. Heat being now applied to the vessel, the solution of
the silver and copper alloys ensues, and after 22 minutes of constant
ebullition, the liquid is poured off and replaced by an equal quantity
of nitric acid, likewise very pure, but of the density 1·28. This is
made to boil for about 10 minutes, and is then poured off, when the
matrass is filled up with distilled water to the brim. In conclusion, a
small annealing crucible is inverted as a cup over the mouth of the
matrass, which is now turned upside down with a steady hand; the slip of
metal falls into the crucible through the water; which by sustaining a
part of its weight, softens its descent and prevents its tearing. The
matrass is then dexterously removed, without letting its water overflow
the crucible. The water is gently decanted from the crucible, which is
next covered, placed in the middle of burning charcoal, and withdrawn
whenever it becomes red hot. After cooling, the metal slip is weighed
very exactly, whence the weight of fine gold in the alloy is known.
Stronger acid than that prescribed above would be apt to tear the
metallic riband to pieces, and it would be difficult to gather the fine
particles of gold together again. The metallic plate becomes at last
merely a golden sieve, with very little cohesion. When copper is to be
separated from gold by cupellation, a higher temperature is requisite
than in cupelling silver coin.

The coining apparatus of the Royal Mint of London is justly esteemed a
masterpiece of mechanical skill and workmanship. It was erected in 1811,
under the direction of the inventor, Mr. Boulton; and has since been
kept in almost constant employment.

[Illustration: 738 739]

The melting pots (_fig._ 738.) are made of cast iron, and hold
conveniently 400 pounds of metal. They are furnished with a spout or lip
for pouring out the metal, and with two ears, on which the tongs of the
crane lay hold in lifting them out of the furnace. The pot rests on
pedestals on the grate of the furnace, and has a ring cast on its edge
to prevent the fuel falling into it. Whenever it becomes red hot, the
metal properly prepared and mixed, so as to produce an alloy containing
0·915 parts of gold, is put in, and during the melting, which occupies
some hours, it is occasionally stirred. The moulds are meanwhile
prepared by warming them in a stove, and thereafter by rubbing their
inside surfaces with a cloth dipped in oil, by which means the ingots
cast in them get a better surface. _Fig._ 739. represents a side view of
the carriage, charged with its moulds. When the proper number of moulds
is introduced, the screws at the end, represented at _t_ T, are screwed
fast, to fix them all tight.

[Illustration: 740]

The pot of fused metal is lifted out of the furnace by the crane (_fig._
740.), then swung round, and lowered down into the cradle _l_, _m_, _n_,
_o_ of the pouring machine, until the ring on the edge of it rests on
the iron hoop _n_, which, being screwed tight up, holds it secure, and
the crane-tongs are removed. One of the assistants now takes the winch
handle _s_ in one hand, and _y_ in the other. By turning _y_ he moves
the carriage forward, so as to bring the first mould beneath the lip of
the melting pot; and by turning _s_, he inclines the pot, and pours the
metal into the mould. He then fills the other moulds in succession. The
first portion of liquid metal is received in a small iron spoon, and is
reserved for the assay-master; a second sample is taken from the centre
of the pot, and a third from the bottom part. Each of these is examined
as to its quality.

The ingots, which are about 10 inches long, 7 broad, and 6 tenths of an
inch thick, are now carried to the rolling mill.

[Illustration: 741]

_Fig._ 741., where A represents a large spur wheel, fixed on the
extremity of a long horizontal shaft B B, extending beneath the whole
mill. This wheel and shaft are driven by a smaller wheel, fixed on the
main or fly-wheel shaft of a steam engine of 36-horse power. The main
shaft B of the rolling mill has wheels C, D, E fixed upon it, to give
motion to the respective rollers, which are mounted at F and G, in
strong iron frames, bolted to the iron sills _a a_, which extend through
the whole length of the mill, and rest upon the masonry, in which the
wheels are concealed. The two large wheels C and E give motion to the
wheels H, I, which are supported on bearings between two standards _b_,
_b_, bolted down to the ground sills. On the ends of the axes of these
wheels are heads for the reception of coupling boxes _d_, _d_, which
unite them to short connecting shafts K L; and these again, by means of
coupling boxes, convey motion to the upper rollers _e_, _e_, of each
pair, at F and G. The middle wheel D upon the-main shaft B gives motion
to the lower rollers in a similar manner. Thus both the rollers _e_, _f_
of each frame receive their motion from the main shaft with equal
velocity, by means of wheels of large radius, which act with much more
certainty than the small pinions usually employed in rolling mills to
connect the upper and lower rollers, and cause them to move together.

The rolling mill contains four pairs of rollers, each driven by its
train of wheel work; the mill, therefore, consists of two such sets of
wheels and rollers as are represented in our figure. The two shafts are
situated parallel to each other, and receive their motion from the same
steam engine. This admirable rolling mill was erected by John Rennie,
Esq.

The ingots are heated to redness in a furnace before they are rolled.
The two furnaces for this purpose are situated before two pairs of
rollers, which, from being used to consolidate the metal by rolling
whilst hot, are termed breaking-down rollers. Two men are employed in
this operation; one taking the metal from the furnace with a pair of
tongs, introduces it between the rollers; and the other, catching it as
it comes through, lifts it over the top roller, and returns it to his
fellow, who puts it through again, having previously approximated the
rollers a little by their adjusting screws. After having been rolled in
this manner four or five times, they are reduced to nearly two-tenths of
an inch thick, and increased lengthwise to about four times the breadth
of the ingot. These plates, while still warm, are rubbed over with a
dilute acid or _pickle_, to remove the colour produced by the heat, and
are then cut up into narrow slips across the breadth of the plate, by
means of the circular shears _fig._ 742.

[Illustration: 742]

This machine is worked by a spur-wheel at the extremity of the main
shaft B of the rolling mill (_fig._ 741.) It consists of a framing of
iron A A, supporting two shafts B B, which are parallel to each other,
and move together by means of two equal spur-wheels C C, the lower one
of which works with the teeth of the great wheel above mentioned, upon
the main shaft of the rolling mill. At the extremities of the two
shafts, wheels or circular cutters are fixed with their edges
overlapping each other a little way. F represents a shelf on which the
plate is laid, and advanced forward to present it to the cutter; and G
is a ledge or guide, screwed down on it, to conduct the metal and to
regulate the breadth of the piece to be cut off. Hence the screws which
fasten down the ledge are fitted in oblong holes, which admit of
adjustment. The workman holds the plate flat upon the surface F, and
pushing it towards the shears, they will lay hold of it, and draw it
through until they have cut the whole length. The divided parts are also
prevented from curling up into scrolls, as they do when cut by a common
pair of shears; because small shoulders on E and D, behind the cutting
edge, keep them straight. Behind the standard, supporting the back
pivots of the shafts B B of the cutter, is a frame _l_, with a screw _m_
tapped through it. This is used to draw the axis of the upper cutter D
endwise, and keep its edge in close contact with the edge of the other
cutter E. The slips or ribands of plate are now carried to the other two
pairs of rollers in the rolling mill, which are made of case-hardened
iron, and better polished than the breaking-down rollers. The plates are
passed cold between these, to bring them to exactly the same thickness;
whence they are called adjusting or planishing rollers. The workman here
tries every piece by a common gauge, as it comes through. This is a
piece of steel having a notch in it; the inside lines of which are very
straight, and inclined to one another at a very acute angle. They are
divided by fine lines, so that the edge of the plate being pressed into
the notch, will have its thickness truly determined by the depth to
which it enters, the divisions showing the thickness in fractions of an
inch.

In rolling the plate the second time, all the plates are successively
passed through the rollers; then the rollers being adjusted, they are
passed through another time. This is repeated thrice or even four times;
after which they are all tried by the gauge, and thus sorted into as
many parcels as there are different thicknesses. It is a curious
circumstance, that though the rollers are no less than 14 inches in
diameter, and their frame proportionally strong, they will yield in some
degree, so as to reduce a thick plate in a less degree than a thin one;
thus the plates which have all passed through the same rollers, may be
of 3 or 4 different degrees of thickness, which being sorted by the
gauge into as many parcels, are next reduced to the exact dimension, by
adapting the rollers to each parcel. The first of the parcel which now
comes through is tried, by cutting out a circular piece with a small
hand machine, and weighing it. If it proves either too light or too
heavy, the rollers are adjusted accordingly, till by a few such trials
they are found to be correct, when all the parcel is rolled through. The
trial plates which turn out to be too thin, are returned as waste to the
melting-house. By these numerous precautions, the blanks or circular
discs, when cut out by the next machine, will be very nearly of the same
weight; which they would scarcely be, even if the gauge determined all
the plates to the same thickness, because some being more condensed than
others, they would weigh differently under the same volume.

[Illustration: 743 744]

A great improvement has been made on that mode of lamination, by the
late Mr. Barton’s machine for equalizing the thickness of slips of metal
for making coin, which has been for several years introduced into the
British mint. A side elevation is shown in _fig._ 743., and a plan in
_fig._ 744. It operates in the same way as wire-drawing mechanisms;
namely, pulls the slips of metal forcibly through an oblong opening,
left between two surfaces of hardened steel. The box or case which
contains the steel dies, composed of two hardened cylinders, is
represented at C in _fig._ 743. The pincers employed to hold the metal,
and draw it through, are shown at _s r_.

The slips of metal to be operated on by the drawing machine, are first
rendered thinner at one end, that they may be introduced between the
dies, and also between the jaws of the pincers. This thinning of the
ends is effected by another machine, consisting of a small pair of
rollers, mounted in an iron frame, similar to a rolling-mill. The upper
roller is cylindrical, but the lower is formed with 3 flat sides,
leaving merely portions of the cylinder entire, between these flat
sides. The distance between the centres of the rollers is regulated by
screws, furnished with wheels on their upper ends, similar to what is
seen in the drawing dies at C. The two rollers have pinions on their
axes, which make them revolve together; they are set in motion by an
endless strap passing round a drum, upon whose axis is a pinion working
into the teeth of a wheel fixed upon the axis of the lower roller.

The end of a slip of metal is presented between the rollers while they
are in motion, not on that side of the roller which would operate to
draw in the slip between them, as in the rolling-press above described,
but on the contrary side, so that when one of the flat sides of the
under roller fronts horizontally the circumference of the upper roller,
an opening is formed, through which the slip of metal is to be inserted
until it bears against a fixed stop at the back of the rollers. As the
rollers continue to turn round, the cylindrical portions come opposite
to each other, and press the metal between them, forcing it outwards,
and rendering the part which has been introduced between the rollers as
thin as the space between their cylindrical surfaces. Thus the end of
the slip of metal becomes attenuated enough to pass between the dies of
the drawing machine, and to be seized by the pincers.

In using the drawing machine, a boy takes hold of the handle _s_ of the
pincers, their hook of connexion with the endless chain _l_, _l_, not
shown in the present figure, being disengaged, and he moves them upon
their wheels towards the die-box C. In this movement the jaws of the
pincers get opened, and they are pushed up so close to the die-box that
their jaws enter a hollow, which brings them near the dies, enabling
them to seize the end of the slip of metal introduced between them by
the action of the preparatory rollers. The boy now holds the handle _s_
on the top of the pincers fast, and with his other hand draws the handle
_x_ backwards. Thus the jaws are closed, and the metal firmly griped. He
now presses down the handle _x_ till a hook on the under side of the
pincers seizes the endless chain as it moves along, when it carries the
pincers, and their slip of metal, onwards with it. Whenever the whole
length of the metallic riband has passed through between the dies, the
strain on the pincers is suddenly relieved, which causes the weight _r_
to raise their hook out of the chain, and stop their motion. The machine
in the mint has two sets of dies, and two endless chains, as represented
in the plan, _fig._ 744. N N, are toothed wheels in the upper end of the
die-box, furnished with pinions and levers, for turning them round, and
adjusting the distance between the dies. A large spur-wheel G, is fixed
upon the axis F, to give motion to the endless chains; see both figures.
This spur-wheel is turned by a pinion H, fixed upon an axis _m_,
extending across the top of the frame, and working in bearings at each
end. A spur-wheel I, is fixed upon the axis _m_, and works into the
teeth of a pinion K, upon a second axis across the frame, which carries
likewise a drum wheel L, through which motion is communicated to the
whole mechanism by an endless strap.

[Illustration: 745]

The cutting-out machine is exhibited in _fig._ 745. A A is a basement of
stone to support an iron plate B B, on which stand the columns C C, that
bear the upper part D of the frame. The iron frame of the machine E, F,
E, is fixed down upon the iron plate B, B. The punch _d_ is fixed in the
lower part of the inner frame, and is moved up and down by the screw
_a_, which is worked by wipers turned by a steam engine, impelling the
lever H, and turning backwards and forwards the axis G, through a
sufficient space for cutting the thickness of the metallic lamina. A boy
manages this machine. There are twelve of them mounted on the same
basement frame in a circular range contained in an elegant room, lighted
from the roof. The whole are moved by a steam engine of 16-horse power.

The _blanks_ or _planchets_ thus cut out, were formerly adjusted by
filing the edges, to bring them to the exact weight; a step which Mr.
Barton’s ingenious mechanism has rendered in a great measure
unnecessary. The edge is then milled, by a process which Mr. Boulton
desires to keep secret, and which is therefore not shown in our mint.

But the French mint employs a very elegant machine for the purpose of
lettering or milling the edges, called the _cordon des monnaies_,
invented by M. Gengembre, which has entirely superseded the older
milling machine of M. Castaing, described in the Encyclopedias. The
Napoleon coins of France bear on the edge, in sunk letters, the legend,
_Dieu protège la France_; and those of the king, _Domine salvum fac
regem_. This is marked before striking the blank or _flan_. One machine
imprints this legend, and its service is so prompt and easy, that a
single man marks in a day 20,000 pieces of 5 francs, or 100,000 francs.

[Illustration: 746]

Each of the two _arc_ dies E, D, (_fig._ 746.) carries one half of the
legend, engraved in relief on the curved face; these arcs are pieces of
steel tempered very hard, and fixed with two screws, one immoveably at
E, on the sill which bears the apparatus; the other at D, at the
extremity of the lever P, D, which turns round the axis C. The letters
of these demi-legends are exactly parallel, and inscribed in an inverse
order on the dies. An alternating circular motion is communicated to the
handle P. The curvatures of the two dies are arcs of circles described
from the centre C; and the interval which separates them, or the
difference of the radii, is precisely the diameter of the piece to be
milled.

As the centre C sustains the whole strain of the milling, and produces,
of consequence, a hard friction, this axis must possess a considerable
size. It is composed of a squat truncated cone of tempered steel, which
enters into an eye of the moveable piece P, D. This cone is kept on the
plate of the metal N N, which bears the whole machine, by a nut, whose
screw, by being tightened or slackened, gives as much freedom as is
requisite for the movement of rotation, or removes the shake which hard
service gives to the cone in its eye. The middle thickness of the hole
of the moveable piece P, D, and the axis of the lever P, which
terminates it, are exactly on a level with the engraved letters of the
die, so that no strain can derange the movable piece, or disturb the
centre by its oscillations.

At _a_ is a vertical tube, containing a pile of blanks for milling. It
is kept constantly full; the tube being open at both ends, a little
elevated above the circular space _a_, K, _b_, which separates the dies,
and fixed by a tail _m_ with a screw to the motionless piece A, B. The
branch I, _c_, movable with the piece P, D, passes under the tube, and
pushes before it the blank at the bottom of the column, which is
received into a small excavation in the form of a circular step, and
carried forwards. Matters are thus so arranged as to regulate the issue
of the blanks, one by one, on the small step, called the _posoir_ (bed.)

As soon as the blank is pushed forwards into contact with the lower edge
of the engraved grooves, it is seized by them, and carried on by the
strain of milling, without exposing the upper or under surfaces of the
_blank_ to any action which may obstruct the printing on its edge.

The blank is observed to revolve between the two dies according as the
lever P completes its course, and this blank passing from _a_ to K, then
to _b_, meets a circular aperture _b_, through which it falls into a
drawer placed under the sill.

The range of the movable lever P is regulated by four pieces, F, F, F,
F, solidly sunk in the plate N, N, which bears the whole apparatus. A
stud placed on this lever towards D, makes the arm of the _posoir_ I _c_
retire no farther than is necessary for the little blank to issue from
the column; and a spring fixed to the centre _c_, and supported on a
peg, brings back the _posoir_; so that when a screw I comes to strike
against the column, the _posoir_ stops, and the movable die D, which
continues its progress, finds the blank in a fit position for pressing,
seizing, and carrying it on, by reaction of the fixed die E. Thus the
edge of the blank is lettered in half a second. A hundred may easily be
marked in about three minutes.

The coining press is the most beautiful part of the whole mechanism in
the British mint; but the limits of this volume will not allow of its
being figured upon an adequate scale. An engraving of it may be seen in
the Encyclopedia Britannica.

The only attention which this noble machine requires is that of a little
boy, who stands in a sunk place before the press, and always keeps the
tube full of blanks. He has two strings, one of which, when pulled, will
put the press in motion by the concealed mechanism in the apartment
above; and the other string, when snatched, stops the press. This
coining operation goes on at the rate of 60 or 70 strokes per minute;
and with very few interruptions during the whole day. The press-room at
the Royal Mint contains eight machines, all supported on the same stone
base; and the iron beams between the columns serve equally for the
presses on each side. The whole has therefore a magnificent appearance.
The eight presses will strike more than 19,000 coins in an hour, with
only a child to supply each. The grand improvement in these presses,
consists; 1. in the precision with which they operate to strike every
coin with equal force, which could not be ensured by the old press
impelled by manual labour; 2. The rising collar or steel ring in which
they are struck, keeps them all of one size, and makes a fair edge,
which was not the case with the old coins, as they were often rounded
and defaced by the expansion of the metal under the blow; 3. The
twisting motion of the upper die is thought to produce a better surface
on the flat parts of the coin; but this is somewhat doubtful; 4. The
feeding mechanism is very complete, and enables the machine to work much
quicker than the old press did, where the workman, being in constant
danger of having his fingers caught, was obliged to proceed cautiously,
as well as to place the coin true on the die, which was seldom perfectly
done. The feeding mechanism of the above press is a French invention;
but Mr. Boulton is supposed to have improved upon it.


MIRRORS. See COPPER and GLASS.


MISPICKEL, is arsenical pyrites.


MOHAIR, is the hair of a goat which inhabits the mountains in the
vicinity of Angora, in Asia Minor.


MOIRÉE METALLIQUE, called in this country crystallized tin-plate, is a
variegated primrose appearance, produced upon the surface of tin-plate,
by applying to it in a heated state some dilute nitro-muriatic acid for
a few seconds, then washing it with water, drying, and coating it with
lacquer. The figures are more or less beautiful and diversified,
according to the degree of heat, and relative dilution of the acid. This
mode of ornamenting tin-plate is much less in vogue now than it was a
few years ago.


MOLASSE, is a sandstone belonging to the tertiary strata, employed under
that name by the Swiss for building.


MOLASSES, is the brown viscid uncrystallizable liquor, which drains from
cane sugar in the colonies. See SUGAR.


MOLYBDENUM (_Molybdène_, Fr.; _Molybdan_, Germ.); is a rare metal which
occurs in nature sometimes as a sulphuret, sometimes as molybdic acid,
and at others as molybdate of lead. Its reduction from the acid state by
charcoal requires a very high heat, and affords not very satisfactory
results. When reduced by passing hydrogen over the ignited acid, it
appears as an ash-gray powder, susceptible of acquiring metallic lustre
by being rubbed with a steel burnisher; when reduced and fused with
charcoal, it possesses a silver white colour, is very brilliant, hard,
brittle, of specific gravity 8·6; it melts in a powerful air-furnace,
oxidizes with heat and air, burns at an intense heat into molybdic acid,
dissolves in neither dilute sulphuric, muriatic, nor fluoric acids, but
in the concentrated sulphuric and nitric.

The protoxide consists of 85·69 of metal, and 14·31 of oxygen; the
deutoxide consists of 75 of metal, and 25 of oxygen; and the peroxide,
or molybdic acid, of 66·6 of metal, and 33·4 of oxygen. These substances
are too rare at present to be used in any manufacture.


MORDANT, in dyeing and calico-printing, denotes a body which, having a
twofold attraction for organic fibres and colouring particles, serves as
a bond of union between them, and thus gives fixity to dyes; or it
signifies a substance which, by combining with colouring particles in
the pores of textile filaments, renders them insoluble in hot soapy and
weak alkaline solutions. In order properly to appreciate the utility and
the true functions of mordants, we must bear in mind that colouring
matters are peculiar compounds possessed of certain affinities, their
distinctive characters being not to be either acid or alkaline, and yet
to be capable of combining with many bodies, and especially with
salifiable bases, and of receiving from each of them modifications in
their colour, solubility, and alterability. Organic colouring
substances, when pure, have a very energetic attraction for certain
bodies, feeble for others, and none at all for some. Among these
immediate products of animal or vegetable life, some are soluble in pure
water, and others become so only through peculiar agents. We may thus
readily conceive, that whenever a dye-stuff possesses a certain affinity
for the organic fibre, it will be able to become fixed on it, or to dye
it without the intervention of mordants, if it be insoluble by itself in
water, which, in fact, is the case with the colouring matters of
safflower, annotto, and indigo. The first two are soluble in alkalis;
hence, in order to use them, they need only be dissolved in a weak
alkaline lye, be thus applied to the stuffs, and then have their
tinctorial substance precipitated within their pores, by abstracting
their solvent alkali with an acid. The colouring matter, at the instant
of ceasing to be liquid, is in an extremely divided state, and is in
contact with the organic fibres for which it has a certain affinity. It
therefore unites with them, and, being naturally insoluble in water,
that is, having no affinity for this vehicle, the subsequent washings
have no effect upon the dye. The same thing may be said of indigo,
although its solubility in the dye-bath does not depend upon a similar
cause, but is due to a modification of its constituent elements, in
consequence of which it becomes soluble in alkalis. Stuffs plunged into
this indigo bath get impregnated with the solution, so that when again
exposed to the air, the dyeing substance resumes at once its primitive
colour and insolubility, and washing can carry off only the portions in
excess above the intimate combination, or which are merely deposited
upon the surface of the stuff.

Such is the result with insoluble colouring matters; but for those which
are soluble it should be quite the reverse, since they do not possess an
affinity for the organic fibres which can counterbalance their affinity
for water. In such circumstances, the dyer must have recourse to
intermediate bodies, which add their affinity for the colouring matter
to that possessed by the particles of the stuff, and increase by this
twofold action the intimacy and the stability of the combination. These
intermediate bodies are the true _mordants_.

Mordants are in general found among the metallic bases or oxides; whence
they might be supposed to be very numerous, like the metals; but as they
must unite the twofold condition of possessing a strong affinity for
both the colouring matter and the organic fibre, and as the insoluble
bases are almost the only ones fit to form insoluble combinations, we
may thus perceive that their number may be very limited. It is well
known, that although lime and magnesia, for example, have a considerable
affinity for colouring particles, and form insoluble compounds with
them, yet they cannot be employed as mordants, because they possess no
affinity for the textile fibres.

Experience has proved, that of all the bases, those which succeed best
as mordants are alumina, tin, and oxide of iron; the first two of which,
being naturally white, are the only ones which can be employed for
preserving to the colour its original tint, at least without much
variation. But whenever the mordant is itself coloured, it will cause
the dye to take a compound colour quite different from its own. If, as
is usually said, the mordant enters into a real chemical union with the
stuff to be dyed, the application of the mordant should obviously be
made in such circumstances as are known to be most favourable to the
combination taking place; and this is the principle of every day’s
practice in the dyehouse.

In order that a combination may result between two bodies, they must not
only be in contact, but they must be reduced to their ultimate
molecules. The mordants that are to be united with stuffs are, as we
have seen, insoluble of themselves, for which reason their particles
must be divided by solution in an appropriate vehicle. Now this solvent
or menstruum will exert in its own favour an affinity for the mordant,
which will prove to that extent an obstacle to its attraction for the
stuff. Hence we must select such solvents as have a weaker affinity for
the mordants than the mordants have for the stuffs. Of all the acids
which can be employed to dissolve alumina, for example, vinegar is the
one which will retain it with least energy, for which reason the acetate
of alumina is now generally substituted for alum, because the acetic
acid gives up the alumina with such readiness, that mere elevation of
temperature is sufficient to effect the separation of these two
substances. Before this substitution of the acetate, alum alone was
employed; but without knowing the true reason, all the French dyers
preferred the alum of Rome, simply regarding it to be the purest; it is
only within these few years that they have understood the real grounds
of this preference. This alum has not, in fact, the same composition as
the alums of France, England, and Germany, but it consists chiefly of
cubic alum having a larger proportion of base. Now this extra portion of
base is held by the sulphuric acid more feebly than the rest, and hence
is more readily detached in the form of a mordant. Nay, when a solution
of cubic alum is heated, this redundant alumina falls down in the state
of a subsulphate, long before it reaches the boiling point. This
difference had not, however, been recognised, because Roman alum, being
usually soiled with ochre on the surface, gives a turbid solution,
whereby the precipitate of subsulphate of alumina escaped observation.
When the liquid was filtered, and crystallized afresh, common octahedral
alum alone was obtained; whence it was most erroneously concluded, that
the preference given to Roman alum was unjustifiable, and that its only
superiority was in being freer from iron.

Here a remarkable anecdote illustrates the necessity of extreme caution,
before we venture to condemn from theory a practice found to be useful
in the arts, or set about changing it. When the French were masters in
Rome, one of their ablest chemists was sent thither to inspect the
different manufactures, and to place them upon a level with the state of
chemical knowledge. One of the fabrics, which seemed to him furthest
behindhand, was precisely that of alum, and he was particularly hostile
to the construction of the furnaces, in which vast boilers received heat
merely at their bottoms, and could not be made to boil. He strenuously
advised them to be new modelled upon a plan of his own; but,
notwithstanding his advice, which was no doubt very scientific, the old
routine kept its ground, supported by utility and reputation, and very
fortunately, too, for the manufacture; for had the higher heat been
given to the boilers, no more genuine cubical alum would have been made,
since it is decomposed at a temperature of about 120° F., and common
octahedral alum would alone have been produced. The addition of a little
alkali to common alum brings it into the same basic state as the alum of
Rome.

The two principal conditions, namely, extreme tenuity of particles, and
liberty of action, being found in a mordant, its operation is certain.
But as the combination to be effected is merely the result of a play of
affinity between the solvent and the stuff to be dyed, a sort of
partition must take place, proportioned to the mass of the solvent, as
well as to its attractive force. Hence the stuff will retain more of the
mordant when its solution is more concentrated, that is, when the base
diffused through it is not so much protected by a large mass of
menstruum; a fact applied to very valuable uses by the practical man. On
impregnating in calico printing, for example, different spots of the
same web with the same mordant in different degrees of concentration,
there is obtained in the dye-bath a depth of colour upon these spots
intense in proportion to the strength of their various mordants. Thus,
with solution of acetate of alumina in different grades of density, and
with madder, every shade can be produced, from the fullest red to the
lightest pink; and, with acetate of iron and madder, every shade from
black to pale violet.

We hereby perceive that recourse must indispensably be had to mordants
at different stages of concentration; a circumstance readily realized by
varying the proportions of the watery vehicle. See CALICO-PRINTING and
MADDER. When these mordants are to be topically applied, to produce
partial dyes upon cloth, they must be thickened with starch or gum, to
prevent their spreading, and to permit a sufficient body of them to
become attached to the stuff. Starch answers best for the more neutral
mordants, and gum for the acidulous; but so much of them should never
be used, as to impede the attraction of the mordant for the cloth. Nor
should the thickened mordants be of too desiccative a nature, lest they
become hard, and imprison the chemical agent before it has had an
opportunity of combining with the cloth, during the slow evaporation of
its water and acid. Hence the mordanted goods, in such a case, should be
hung up to dry in a gradual manner, and when oxygen is necessary to the
fixation of the base, they should be largely exposed to the atmosphere.
The foreman of the factory ought, therefore, to be thoroughly conversant
with all the minutiæ of chemical reaction. In cold and damp weather he
must raise the temperature of his drying-house, in order to command a
more decided evaporation; and when the atmosphere is unusually dry and
warm, he should add deliquescent correctives to his thickening, as I
have particularized in treating of some styles of calico-printing. But,
supposing the application of the mordant and its desiccation to have
been properly managed, the operation is by no means complete; nay, what
remains to be done is not the least important to success, nor the least
delicate of execution. Let us bear in mind that the mordant is intended
to combine not only with the organic fibre, but afterwards also with the
colouring matter, and that, consequently, it must be laid entirely bare,
or scraped clean, so to speak, that is, completely disengaged from all
foreign substances which might invest it, and obstruct its intimate
contact with the colouring matters. This is the principle and the object
of two operations, to which the names of _dunging_ and _clearing_ have
been given.

If the mordant applied to the surface of the cloth were completely
decomposed, and the whole of its base brought into chemical union with
it, a mere rinsing or scouring in water would suffice for removing the
viscid substances added to it, but this never happens, whatsoever
precautions may be taken; one portion of the mordant remains untouched,
and besides, one part of the base of the portion decomposed does not
enter into combination with the stuff, but continues loose and
superfluous. All these particles, therefore, must be removed without
causing any injury to the dyes. If in this predicament the stuff were
merely immersed in water, the free portion of the mordant would
dissolve, and would combine indiscriminately with all the parts of the
cloth not mordanted, and which should be carefully protected from such
combination, as well as the action of the dye. We must therefore add to
the scouring water some substance that is capable of seizing the mordant
as soon as it is separated from the cloth, and of forming with it an
insoluble compound; by which means we shall withdraw it from the sphere
of action, and prevent its affecting the rest of the stuff, or
interfering with the other dyes. This result is obtained by the addition
of cow-dung to the scouring bath; a substance which contains a
sufficiently great proportion of soluble animal matters, and of
colouring particles, for absorbing the aluminous and ferruginous salts.
The heat given to the dung-bath accelerates this combination, and
determines an insoluble and perfectly inert coagulum.

Thus the dung-bath produces at once the solution of the thickening
paste; a more intimate union between the alumina or iron and the stuff,
in proportion to its elevation of temperature, which promotes that
union; an effectual subtraction of the undecomposed and superfluous part
of the mordant, and perhaps a commencement of mechanical separation of
the particles of alumina, which are merely dispersed among the fibres; a
separation, however, which can be completed only by the proper scouring,
which is done by the dash-wheel with such agitation and pressure (see
BLEACHING and DUNGING) as vastly facilitate the expulsion of foreign
particles. See also BRAN.

Before concluding this article, we may say a word or two about
astringents, and especially gall-nuts, which have been ranked by some
writers among mordants. It is rather difficult to account for the part
which they play. Of course we do not allude to their operation in the
black dye, where they give the well known purple-black colour with salts
of iron; but to the circumstance of their employment for madder dyes,
and especially the Adrianople red. All that seems to be clearly
established is, that the astringent principle or tannin, whose peculiar
nature in this respect is unknown, combines like mordants with the
stuffs and the colouring substance, so as to fix it; but as this tannin
has itself a brown tint, it will not suit for white grounds, though it
answers quite well for pink grounds. When white spots are desired upon a
cloth prepared with oil and galls, they are produced by an oxygenous
discharge, effected either through chlorine or chromic acid.


MORDANT, is also the name sometimes given to the adhesive matter by
which gold-leaf is made to adhere to surfaces of wood and metal in
gilding. Paper, vellum, taffety, &c., are easily gilt by the aid of
different mordants, such as the following: 1. beer in which some honey
and gum arabic have been dissolved; 2. gum arabic, sugar, and water; 3.
the viscid juice of onion or hyacinth, strengthened with a little gum
arabic. When too much gum is employed, the silver or gold leaf is apt to
crack in the drying of the mordant. A little carmine should be mixed
with the above colourless liquids, to mark the places where they are
applied. The foil is applied by means of a dossil of cotton wool, and
when the mordant has become hard, the foil is polished with the same.

The best medium for sticking gold and silver leaf to wood, is the
following, called _mixtion_ by the French artists:--1 pound of amber is
to be fused, with 4 ounces of mastic in tears, and 1 ounce of Jewish
pitch, and the whole dissolved in 1 pound of linseed oil rendered drying
by litharge.

Painters in distemper sometimes increase the effect of their work, by
patches of gold leaf, which they place in favourable positions; they
employ the above mordant. The manufacturers of paper hangings of the
finer kinds attach gold and silver leaf to them by the same varnish.


MOROCCO. See LEATHER.


MORPHIA (_Morphine_, Fr.; _Morphin_, Germ.), is a vegeto-alkali which
exists associated with opian, codeïne, narcotine, meconine, meconic
acid, resin, gum, bassorine, lignine, fat oil, caoutchouc, extractive,
&c., in opium. Morphia is prepared as follows: Opium in powder is to be
repeatedly digested with dilute muriatic acid, slightly heated, and
sea-salt is to be added, to precipitate the opian. The filtered liquid
is to be supersaturated with ammonia, which throws down the morphia,
along with the meconine, resin, and extractive. The precipitate is to be
washed with water, heated, and dissolved in dilute muriatic acid; the
solution is to be filtered, whereby the foreign matters are separated
from the salt of morphia, which concretes upon cooling, while the
meconine remains in the acid liquid. The muriate of morphia having been
squeezed between folds of blotting paper, is to be sprinkled with water,
again squeezed, next dissolved in water, and decomposed by water of
ammonia. The precipitate, when washed, dried, dissolved in alcohol, and
crystallized, is morphia.

These crystals, which contain 6·32 per cent. of combined water, are
transparent, colourless, four-sided prisms, without smell, and nearly
void of taste, fusible at a moderate heat, and then concrete into a
radiated translucent mass, but at a higher temperature they grow
purple-red. Morphia consists of 72·34 of carbon; 6·366 of hydrogen; 5 of
azote; and 16·3 of oxygen. It burns with a red and very smoky flame, is
stained red by nitric acid, is soluble in 30 parts of boiling anhydrous
alcohol, in 500 parts of boiling water, but hardly if at all in cold
water, and is insoluble in ether and oils. The solutions have a strong
bitter taste, and an alkaline reaction upon litmus paper. The saline
compounds have a bitter taste, are mostly crystallizable, are soluble in
water and alcohol (but not in ether), and give a blue colour to the
peroxide salts of iron. It is a very poisonous substance. Acetate of
morphia is sometimes prescribed, instead of opium, in medicine.


MORTAR, HYDRAULIC, called also _Roman Cement_, is the kind of mortar
used for building piers, or walls under or exposed to water, such as
those of harbours, docks, &c. The poorer sorts of limestone are best
adapted for this purpose, such as contain from 8 to 25 per cent. of
foreign matter, in silica, alumina, magnesia, &c. These, though
calcined, do not slake when moistened; but if pulverized they absorb
water without swelling up or heating, like _fat_ lime, and afford a
paste which hardens in a few days under water, but in the air they never
acquire much solidity. Smeaton first discovered these remarkable facts,
and described them in 1759.

The following analyses of different hydraulic limestones, by Berthier,
merit confidence:--

  +---------------------------------+------+------+------+------+------+
  |                                 |No. 1.|No. 2.|No. 3.|No. 4.|No. 5.|
  |                                 +------+------+------+------+------+
  | A. _Analyses of limestones._    |      |      |      |      |      |
  |Carbonate of lime                | 97·0 | 98·5 | 74·5 |  76·5|  80·0|
  |Carbonate of magnesia            |  2·0 |  --  | 23·0 |   3·0|   1·5|
  |Carbonate of protoxide of iron   |  --  |  --  |  --  |   3·0|   -- |
  |Carbonate of manganese           |  --  |  --  |  --  |   1·5|   -- |
  |Silica and alumina               |  1·0 |  1·5 |  1·2 |} 15·2|} 18·0|
  |Oxide of iron                    |      |      |      |}     |}     |
  |                                 +------+------+------+------+------+
  |                                 |100·0 |100·0 |100·0 | 100·0| 100·0|
  +---------------------------------+------+------+------+------+------+
  | B. _Analyses of the burnt lime._|      |      |      |      |      |
  |Lime                             | 96·4 | 97·2 | 78·0 |  68·3|  70·0|
  |Magnesia                         |  1·8 |  --  | 20·0 |   2·0|   1·0|
  |Alumina                          |  1·8 |  2·8 |  2·0 |  24·0|  29·0|
  |Oxide of iron                    |  --  |  --  |  --  |   5·7|   -- |
  |                                 +------+------+------+------+------+
  |                                 |100·0 |100·0 |100·0 | 100·0| 100·0|
  +---------------------------------+------+------+------+------+------+

No. 1. is from the fresh-water lime formation of Château-Landon, near
Nemours; No. 2. the large-grained limestone of Paris; both of these
afford a fat lime when burnt. Dolomite affords a pretty fat lime, though
it contains 42 per cent. of carbonate of magnesia; No. 3. is a limestone
from the neighbourhood of Paris, which yields a poor lime, possessing no
hydraulic property; No. 4. is the secondary limestone of Metz; No. 5. is
the lime marl of Senonches, near Dreux; both the latter have the
property of hardening under water, particularly the last, which is much
used at Paris on this account.

All good hydraulic mortars must contain alumina and silica; the oxides
of iron and manganese, at one time considered essential, are rather
prejudicial ingredients. By adding silica and alumina, or merely the
former, in certain circumstances, to fat lime, a water-cement may be
artificially formed; as also by adding to lime any of the following
native productions, which contain silicates; puzzolana, trass or tarras,
pumice-stone, basalt-tuff, slate-clay. Puzzolana is a volcanic product,
which forms hills of considerable extent to the south-west of the
Appenines, in the district of Rome, the Pontine marshes, Viterbo,
Bolsena, and in the Neapolitan region of Puzzuoli, whence the name. A
similar volcanic tufa is found in many other parts of the world.
According to Berthier, the Italian puzzolana consists of 44·5 silica;
15·0 alumina; 8·8 lime; 4·7 magnesia; 1·4 potash; 4·1 soda; 12 oxides of
iron and titanium; 9·2 water; in 100 parts.

The _tufa_ stone, which when ground forms _trass_, is composed of 57·0
silica, 16·0 clay, 2·6 lime, 1·0 magnesia, 7·0 potash, 1·0 soda, 5
oxides of iron and titanium, 9·6 water. This tuff is found abundantly
filling up valleys in beds of 10 or 20 feet deep, in the north of
Ireland, among the schistose formations upon the banks of the Rhine, and
at Monheim in Bavaria.

The fatter the lime, the less of it must be added to the ground
puzzolana or trass, to form a hydraulic mortar; the mixture should be
made extemporaneously, and must at any rate be kept dry till about to be
applied. Sometimes a proportion of common sand mortar instead of lime is
mixed with the trass. When the hydraulic cement hardens too soon, as in
12 hours, it is apt to crack; it is better when it takes 8 days to
concrete. Through the agency of the water, silicates of lime, alumina,
(magnesia), and oxide of iron are formed, which assume a stony hardness.

Besides the above two volcanic products, other native earthy compounds
are used in making water cements. To this head belong all limestones
which contain from 20 to 30 per cent. of clay and silica. By gentle
calcination, a portion of the carbonic acid is expelled, and a little
lime is combined with the clay, while a silicate of clay and lime
results, associated with lime in a subcarbonated state. A lime-marl
containing less clay will bear a stronger calcining heat without
prejudice to its qualities as a hydraulic cement; but much also depends
upon the proportion of silica present, and the physical structure of all
the constituents.

The mineral substance most used in England for making such mortar, is
vulgarly called _cement-stone_. It is a reniform limestone, which occurs
distributed in single nodules or rather lenticular cakes, in beds of
clay. They are mostly found in those argillaceous strata which alternate
with the limestone beds of the oolite formation, as also in the clay
strata above the chalk, and sometimes in the London clay. On the coasts
of Kent, in the isles of Sheppey and Thanet, on the coasts of Yorkshire,
Somersetshire, and the Isle of Wight, &c., these nodular concretions are
found in considerable quantities, having been laid bare by the action of
the sea and weather. They were called by the older mineralogists
_Septaria_ and _Ludus Helmontii_ (Van Helmont’s coits). When sawn
across, they show veins of calc-spar traversing the siliceous clay, and
are then sometimes placed in the cabinets of _virtuosi_. They are found
also in several places on the Continent, as at Neustadt-Eberswalde, near
Antwerp, near Altdorf in Bavaria; as also at Boulogne-sur-mer, where
they are called Boulogne-pebbles (_galets_). These nodules vary in size
from that of a fist to a man’s head, they are of a yellow-gray or brown
colour, interspersed with veins of calc-spar, and sometimes contain
cavities bestudded with crystals. Their specific gravity is 2·59.

Analyses of several cement-stones, and of the cement made with them:--

  +------------------------------+------+------+------+------+------+
  |                              |No. 1.|No. 2.|No. 3.|No. 4.|No. 5.|
  +------------------------------+------+------+------+------+------+
  |A. _Constituents of the       |      |      |      |      |      |
  |    cement-stones._           |      |      |      |      |      |
  |Carbonate of lime             | 65·7 | 61·6 |      | 82·9 | 63·8 |
  |   ----      magnesia         |  0·5 |      |      |      |  1·5 |
  |   ----      protoxide of iron|  6·0 |  6·0 |      | }    | 11·6 |
  |   ----      manganese        |  1·6 |      |      | }4·3 |      |
  |Silica                        | 18·0 | 15·0 |      | 13·0 | 14·0 |
  |Alumina or clay               |  6·6 |  4·8 |      |trace |  5·7 |
  |Oxide of iron                 |      |  3·0 |      |      |      |
  |Water                         |  1·2 |  6·6 |      |      |  3·4 |
  |                              |      |      |      |      |      |
  |B. _Constituents of the       |      |      |      |      |      |
  |cement._                      |      |      |      |      |      |
  |Lime                          | 55·4 | 54·0 | 55·0 |      | 56·6 |
  |Magnesia                      |      |      |      |      |  1·1 |
  |Alumina or clay               | 36·0 | 31·0 | 38·0 |      | 21·0 |
  |Oxide of iron                 |  8·6 | 15·0 | 13·0 |      | 13·7 |
  +------------------------------+------+------+------+------+------+

No. 1. English cement-stone, analyzed by Berthier; No. 2. Boulogne
stone, by Drapiez; No. 3. English ditto, by Davy; No. 4. reniform
limestone nodules from Arkona, by Hühnefeld; No. 5. cement-stone of
Avallon, by Dumas.

In England the stones are calcined in shaft-kilns, or sometimes in
mound-kilns, then ground, sifted, and packed in casks. The colour of the
powder is dark-brown-red. When made into a thick paste with water, it
absorbs little of it, evolves hardly any heat, and soon indurates. It is
mixed with sharp sand in various proportions, immediately before using
it; and is employed in all marine and river embankments, for securing
the seams of stone or brick floors or arches from the percolation of
moisture, and also for facing walls to protect them from damp.

The cement of Pouilly is prepared from a Jurassic (secondary) limestone,
which contains 39 per cent. of silica, with alumina, magnesia, and iron
oxide. Vicat forms a factitious Roman cement by making bricks with a
pasty mixture of 4 parts of chalk, and 1 part of dry clay, drying,
burning, and grinding them. River sand must be added to this powder; and
even with this addition, its efficacy is somewhat doubtful; though it
has, for want of a better substitute, been much employed at Paris.

The cement of Dihl consists of porcelain or salt-glaze potsherds ground
fine, and mixed with boiled linseed oil.

Hamelin’s mastic or lithic paint to cover the façades of brick
buildings, &c., is composed of 50 measures of siliceous sand, 50 of
lime-marl, and 9 of litharge or red-lead ground up with linseed oil.


MOSAIC GOLD. For the composition of this peculiar alloy of copper and
zinc, called also _Or-molu_, Messrs. Parker and Hamilton obtained a
patent in November, 1825. Equal quantities of copper and zinc are to be
“melted at the lowest temperature that copper will fuse,” which being
stirred together so as to produce a perfect admixture of the metals, a
further quantity of zinc is added in small portions, until the alloy in
the melting pot becomes of the colour required. If the temperature of
the copper be too high, a portion of the zinc will fly off in vapour,
and the result will be merely spelter or hard solder; but if the
operation be carried on at as low a heat as possible, the alloy will
assume first a brassy yellow colour; then, by the introduction of small
portions of zinc, it will take a purple or violet hue, and will
ultimately become perfectly white; which is the appearance of the proper
compound in its fused state. This alloy may be poured into ingots; but
as it is difficult to preserve its character when re-melted, it should
be cast directly into the figured moulds. The patentees claim the
exclusive right of compounding a metal consisting of from 52 to 55 parts
of zinc out of 100.

_Mosaic gold_, the _aurum musivum_ of the old chemists, is a sulphuret
of tin.


MOSAIC. (_Mosaïque_, Fr.; _Mosaisch_, Germ.) There are several kinds of
mosaic, but all of them consist in imbedding fragments of different
coloured substances, usually glass or stones, in a cement, so as to
produce the effect of a picture. The beautiful chapel of Saint Lawrence
in Florence, which contains the tombs of the Medici, has been greatly
admired by artists, on account of the vast multitude of precious
marbles, jaspers, agates, avanturines, malachites, &c., applied in
mosaic upon its walls. The detailed discussion of this subject belongs
to a treatise upon the fine arts.


MOTHER OF PEARL (_Nacre de Perles_, Fr.; _Perlen mutter_, Germ.); is the
hard, silvery, brilliant internal layer of several kinds of shells,
particularly oysters, which is often variegated with changing purple and
azure colours. The large oysters of the Indian seas alone secrete this
coat of sufficient thickness to render their shells available to the
purposes of manufactures. The genus of shell fish called _pentadinæ_
furnishes the finest pearls, as well as mother of pearl; it is found in
greatest perfection round the coasts of Ceylon, near Ormus in the
Persian Gulf, at Cape Comorin, and among some of the Australian seas.
The brilliant hues of mother of pearl, do not depend upon the nature of
the substance, but upon its structure. The microscopic wrinkles or
furrows which run across the surface of every slice, act upon the
reflected light in such a way as to produce the chromatic effect; for
Sir David Brewster has shown, that if we take, with very fine black
wax, or with the fusible alloy of D’Arcet, an impression of mother of
pearl, it will possess the iridescent appearance. Mother of pearl is
very delicate to work, but it may be fashioned by saws, files, and
drills, with the aid sometimes of a corrosive acid, such as the dilute
sulphuric or muriatic; and it is polished by colcothar of vitriol.


MOTHER-WATER, is the name of the liquid which remains after all the
salts that will regularly crystallize have been extracted, by
evaporation and cooling, from any saline solution.


MOUNTAIN SOAP (_Savon de montagne_, Fr.; _Bergseife_, Germ.); is a
tender mineral, soft to the touch, which assumes a greasy lustre when
rubbed, and falls to pieces in water. It consists of silica 44, alumina
26·5, water 20·5, oxide of iron 8, lime 0·5. It occurs in beds,
alternating with different sorts of clay, in the Isle of Skye, at Billin
in Bohemia, &c. It has been often, but improperly, confounded with
steatite.


MUCIC ACID (_Acid mucique_, Fr.; _Schleimsaüre_, Germ.); is the same as
the saclactic acid of Scheele, and may be obtained by digesting one part
of gum arabic, sugar of milk, or pectic acid, with twice or thrice their
weight of nitric acid. It forms white granular crystals, and has not
been applied to any use in the arts.


MUCILAGE, is a solution in water of gummy matter of any kind.


MUFFLE, is the earthenware case or box, in the assay furnaces, for
receiving the cupels, and protecting them from being disturbed by the
fuel. See ASSAY and FURNACE.


MUNDIC, is the name of copper pyrites among English miners.


MUNJEET, is a kind of madder grown in several parts of India.


MURIATIC or HYDROCHLORIC ACID; anciently _marine acid_, and _spirit of
salt_. (_Acide hydrochlorique_, and _Chlorhydrique_, Fr.; _Salzsaüre_,
Germ.) This acid is now extracted from sea-salt, by the action of
sulphuric acid and a moderate heat; but it was originally obtained from
the salt by exposing a mixture of it and of common clay to ignition in
an earthen retort. The acid gas which exhales, is rapidly condensed by
water. 100 cubic inches of water are capable of absorbing no less than
48,000 cubic inches of the acid gas, whereby the liquid acquires a
specific gravity of 1·2109; and a volume of 142 cubic inches. This vast
condensation is accompanied with a great production of heat, whence it
becomes necessary to apply artificial refrigeration, especially if so
strong an acid as the above is to be prepared. In general, the muriatic
acid of commerce has a specific gravity varying from 1·15 to 1·20; and
contains, for the most part, considerably less than 40 parts by weight
of acid gas in the hundred. The above stronger acid contains 42·68 per
cent. by weight; for since a cubic inch of water, which weighs 252·5
grains, has absorbed 480 cubic inches = 188 grains of gas; and 252·5 +
188 = 440·5; then 440·5 : 188 ∷ 100 : 42·68. In general a very good
approximation may be found to the percentage of real muriatic acid, in
any liquid sample, by multiplying the decimal figures of the specific
gravity by 200. Thus for example, at 1·162 we shall have by this rule
0·162 × 200 = 32·4, for the quantity of gas in 100 parts of the liquid.
Muriatic acid gas consists of chlorine and hydrogen combined, without
condensation, in equal volumes. Its specific gravity is 1·247, air =
1·000.

By sealing up muriate of ammonia and sulphuric acid, apart, in a strong
glass tube recurved, and then causing them to act on each other, Sir H.
Davy procured liquid muriatic acid. He justly observes, that the
generation of elastic substances in close vessels, either with or
without heat, offers much more powerful means of approximating their
molecules than those dependent on the application of cold, whether
natural or artificial; for as gases diminish only 1/480 in volume for
every degree of Fahrenheit’s scale, beginning at ordinary temperatures,
a very slight condensation only can be produced by the most powerful
freezing mixtures, not half as much as would result from the application
of a strong flame to one part of a glass tube, the other part being of
ordinary temperature: and when attempts are made to condense gases into
liquids by sudden mechanical compression, the heat instantly generated
presents a formidable obstacle to the success of the experiment; whereas
in the compression resulting from their slow generation in close
vessels, if the process be conducted with common precautions, there is
no source of difficulty or danger; and it may be easily assisted by
artificial cold, in cases where gases approach near to that point of
compression and temperature at which they become vapours.--_Phil.
Trans._ 1823.

The muriatic acid of commerce has usually a yellowish tinge, but when
chemically pure it is colourless. It fumes strongly in the air, emitting
a corrosive vapour of a peculiar smell. The characteristic test of
muriatic acid in the most dilute state, is nitrate of silver, which
causes a curdy precipitate of chloride of silver.

The preparation of this acid upon the great scale is frequently effected
in this country by acting upon sea-salt in hemispherical iron pots, or
in cast-iron cylinders, with concentrated sulphuric acid; taking 6 parts
of the salt to 5 of the acid. The mouth of the pot may be covered with a
slab of siliceous freestone, perforated with two holes of about two
inches diameter each, into the one of which the acid is poured by a
funnel in successive portions, and into the other, a bent glass, or
stone-ware tube, is fixed, for conducting the disengaged muriatic gas
into a series of large globes of bottle glass, one-third filled with
water, and laid on a sloping sand-bed. A week is commonly employed for
working off each pot; no heat being applied to it till the second day.

The decomposition of sea-salt by sulphuric acid, was at one time carried
on by some French manufacturers in large leaden pans, 10 feet long, 5
feet broad, and a foot deep, covered with sheets of lead, and luted. The
disengaged acid gas was made to circulate in a conduit of glazed bricks,
nearly 650 yards long, where it was condensed by a sheet of water
exceedingly thin, which flowed slowly in the opposite direction of the
gas down a slope of 1 in 200. At the end of this canal nearest the
apparatus, the muriatic acid was as strong as possible, and pretty pure;
but towards the other end, the water was hardly acidulous. The
condensing part of this apparatus was therefore tolerably complete; but
as the decomposition of the salt could not be finished in the leaden
pans, the acid mixture had to be drawn out of them, in order to be
completely decomposed in a reverberatory furnace; in this way nearly 50
per cent. of the muriatic acid was lost. And besides, the great quantity
of gas given off during the emptying of the lead-chambers was apt to
suffocate the workmen, or seriously injured their lungs, causing severe
hemoptysis. The employment of muriatic acid is so inconsiderable, and
the loss of it incurred in the preceding process is of so little
consequence, that subsequently, both in France and in England, sulphate
of soda, for the soda manufacture, has been procured with the
dissipation of the muriatic acid in the air. In the method more lately
resorted to, the gaseous products are discharged into extensive vaults,
where currents of water condense them and carry them off into the river.
The surrounding vegetation is thereby saved in some measure from being
burned up, an accident which was previously sure to happen when fogs
precipitated the floating gases upon the ground. At Newcastle,
Liverpool, and Marseilles, where the consumption of muriatic acid bears
no proportion to the manufacture of soda, this process is now practised
upon a vast scale.

The apparatus for condensing muriatic acid gas has been modified and
changed, of late years, in many different ways.

_The Bastringue apparatus._ At the end of a reverberatory furnace, (see
COPPER, SMELTING OF, and SODA, MANUFACTURE OF,) a rectangular lead
trough or pan, about 1 foot deep, of a width equal to that of the
interior of the furnace, that is about 5 feet wide, and 6-1/2 feet long,
is encased in masonry, having its upper edges covered with cast-iron
plates or fire tiles, and placed upon a level with the passage of the
flame, as it escapes from the reverberatory. The arch which covers that
pan forms a continuation of the roof of the reverberatory, and is of the
same height. The flame which proceeds from the furnace containing the
mixture of salt and sulphuric acid is made to escape between the vault
and the surface of the iron plates or fire tiles, through a passage only
4 inches in height. When the burned air and vapours reach the extremity
of the pan, they are reflected downwards, and made to return beneath the
bottom of the pan, in a flue, which is afterwards divided so as to lead
the smoke into two lateral flues, which terminate in the chimney. The
pan is thus surrounded as it were with the heat and flame discharged
from the reverberatory furnace. See EVAPORATION. A door is opened near
the end of the pan, for introducing the charge of sea-salt, amounting to
12 bags of 2 cwt. each, or 24 cwt. This door is then luted on as tightly
as possible, and for every 100 parts of salt, 110 of sulphuric acid are
poured in, of specific gravity 1·594, containing 57 per cent. of dry
acid. This acid is introduced through a funnel inserted in the roof of
the furnace. Decomposition ensues, muriatic acid gas mingled with steam
is disengaged, and is conducted through 4 stone-ware tubes into the
refrigerators, where it is finally condensed. These refrigerators
consist of large stone-ware carboys, called _dame-jeans_ in France, to
the number of 7 or 8 for each pipe, and arranged so that the neck of the
one communicates with the body of the other; thus the gas must traverse
the whole series, and gets in a good measure condensed by the water in
them, before reaching the last.

When the operation is finished, the door opposite the pan is opened, and
the residuum in it, is discharged, in the form of a fluid magma, upon a
square bed of bricks, exterior to the furnace. This paste speedily
concretes on cooling, and is then broken into fragments and carried to
the soda manufactory. The immense quantity of gas exhaled in discharging
the pan, renders this part of the operation very painful to the workmen;
and wasteful in reference to the production of muriatic acid. The
difficulty of luting securely the cast-iron plates or fire tiles which
cover the pan, the impossibility of completing the decomposition of the
salt, since the residuum must be run off in a liquid state, finally, the
damage sustained by the melting and corrosion of the lead, &c., are
among the causes why no more than 80 or 90 parts of muriatic acid at
1·170 are collected, equivalent to 25 per cent. of real acid for every
100 of salt employed, instead of much more than double that quantity,
which it may be made to yield by a well conducted chemical process.

[Illustration: 747 748]

The _cylinder apparatus_ is now much esteemed by many manufacturers.
_Fig._ 747. represents, in transverse section, a bench of iron cylinder
retorts, as built up in a proper furnace for producing muriatic acid;
and _fig._ 748. a longitudinal section of one retort with one of its
carboys of condensation. _a_ is the grate; _b_, a fireplace, in which
two iron cylinders, _c c_, are set alongside of each other. They are
5-1/2 feet long, 20 inches in diameter, about 1/4 of an inch thick, and
take 1·6 cwts. of salt for a charge; _d_ is the ash-pit; _e_, _e_, are
cast-iron lids, for closing both ends of the cylinders; _f_ is a tube in
the posterior lid, for pouring in the sulphuric acid; _g_ is another
tube, in the anterior lid, for the insertion of the bent pipe of hard
glazed stone-ware _h_; _i_ is a three-necked stone-ware carboy; _k_ is a
tube of safety; _l_, a tube of communication with the second carboy; _m
m_, _m m_, are the flues leading to the chimney _n_.

After the salt has been introduced, and the fire kindled, 83-1/4 per
cent. of its weight of sulphuric acid, of spec. grav. 1·80, should be
slowly poured into the cylinder through a lead funnel, with a
syphon-formed pipe. The three-necked carboys may be either placed in a
series for each retort, like a range of Woulfe’s bottles, or all the
carboys of the front range may be placed in communication with one
another, while the last carboy at one end is joined to the first of the
second range; and thus in succession. They must be half filled with cold
water; and when convenient, those of the front row at least, should be
plunged in an oblong trough of running water. The acid which condenses
in the carboys of that row is apt to be somewhat contaminated with
sulphuric acid, muriate of iron, or even sulphate of soda; but that in
the second and third will be found to be pure. In this way 100 parts of
sea-salt will yield 130 parts of muriatic acid, of spec. grav. 1·19;
while the sulphate of soda in the retort will afford from 208 to 210 of
that salt in crystals.

It is proper to heat all the parts of the cylinders equably, to insure
the simultaneous decomposition of the salt, and to protect it from the
acid; for the hotter the iron, and the stronger the acid, the less
erosion ensues.

Some manufacturers, with the view of saving fuel by the construction of
their furnaces oppose to the flame as many obstacles as they can, and
make it perform numerous circulations round the cylinders; but this
system is bad, and does not even effect the desired economy, because the
passages, being narrow, impair the draught, and become speedily choked
up with the soot, which would be burned profitably in a freer space; the
decomposition also, being unequally performed, is less perfect, and the
cylinders are more injured. It is better to make the flame envelope at
once the body of the cylinder; after which it may circulate beneath the
vault, in order to give out a portion of its caloric before it escapes
at the chimney.

The fire should be briskly kindled, but lowered as soon as the
distillation commences; and then continued moderate till the evolution
of gas diminishes, when it must be heated somewhat strongly to finish
the decomposition. The iron door is now removed, to extract the
sulphate of soda, and to recommence another operation. This sulphate
ought to be white and uniform, exhibiting in its fracture no
undecomposed sea-salt.

Liquid muriatic acid has a very sour corrosive taste, a pungent
suffocating smell, and acts very powerfully upon a vast number of
mineral, vegetable, and animal substances. It is much employed for
making many metallic solutions; and in combination with nitric acid, it
forms the aqua regia of the alchemists, so called from its property of
dissolving gold.

Table of Muriatic Acid, by Dr. Ure.

  +-------+--------+---------+--------+
  | Acid  |Specific|Chlorine.|Muriatic|
  |of 120 |gravity.|         |  Gas.  |
  |in 100.|        |         |        |
  +-------+--------+---------+--------+
  |  100  | 1·2000 | 39·675  | 40·777 |
  |   99  | 1·1982 | 39·278  | 40·369 |
  |   98  | 1·1964 | 38·882  | 39·961 |
  |   97  | 1·1946 | 38·485  | 39·554 |
  |   96  | 1·1928 | 38·089  | 39·146 |
  |   95  | 1·1910 | 37·692  | 38·738 |
  |   94  | 1·1893 | 37·296  | 38·330 |
  |   93  | 1·1875 | 36·900  | 37·923 |
  |   92  | 1·1857 | 36·503  | 37·516 |
  |   91  | 1·1846 | 36·107  | 37·108 |
  |   90  | 1·1822 | 35·707  | 36·700 |
  |   89  | 1·1802 | 35·310  | 36·292 |
  |   88  | 1·1782 | 34·913  | 35·884 |
  |   87  | 1·1762 | 34·517  | 35·476 |
  |   86  | 1·1741 | 34·121  | 35·068 |
  |   85  | 1·1721 | 33·724  | 34·660 |
  |   84  | 1·1701 | 33·328  | 34·252 |
  |   83  | 1·1681 | 32·931  | 33·845 |
  |   82  | 1·1661 | 32·535  | 33·437 |
  |   81  | 1·1641 | 32·136  | 33·029 |
  |   80  | 1·1620 | 31·746  | 32·621 |
  |   79  | 1·1599 | 31·343  | 32·213 |
  |   78  | 1·1578 | 30·946  | 31·805 |
  |   77  | 1·1557 | 30·550  | 31·398 |
  |   76  | 1·1536 | 30·153  | 30·990 |
  |   75  | 1·1515 | 29·757  | 30·582 |
  |   74  | 1·1494 | 29·361  | 30·174 |
  |   73  | 1·1473 | 28·964  | 29·767 |
  |   72  | 1·1452 | 28·567  | 29·359 |
  |   71  | 1·1431 | 28·171  | 28·951 |
  |   70  | 1·1410 | 27·772  | 28·544 |
  |   69  | 1·1389 | 27·376  | 28·136 |
  |   68  | 1·1369 | 26·979  | 27·728 |
  |   67  | 1·1349 | 26·583  | 27·321 |
  |   66  | 1·1328 | 26·186  | 26·913 |
  |   65  | 1·1308 | 25·789  | 26·505 |
  |   64  | 1·1287 | 25·392  | 26·098 |
  |   63  | 1·1267 | 24·996  | 25·690 |
  |   62  | 1·1247 | 24·599  | 25·282 |
  |   61  | 1·1226 | 24·202  | 24·874 |
  |   60  | 1·1206 | 23·805  | 24·466 |
  |   59  | 1·1185 | 23·408  | 24·058 |
  |   58  | 1·1164 | 23·012  | 23·050 |
  |   57  | 1·1143 | 22·615  | 23·242 |
  |   56  | 1·1123 | 22·218  | 22·834 |
  |   55  | 1·1102 | 21·822  | 22·426 |
  |   54  | 1·1082 | 21·425  | 22·019 |
  |   53  | 1·1061 | 21·028  | 21·611 |
  |   52  | 1·1041 | 20·632  | 21·203 |
  |   51  | 1·1020 | 20·235  | 20·796 |
  |   50  | 1·1000 | 19·837  | 20·388 |
  |   49  | 1·0980 | 19·440  | 19·980 |
  |   48  | 1·0960 | 19·044  | 19·572 |
  |   47  | 1·0939 | 18·647  | 19·165 |
  |   46  | 1·0919 | 18·250  | 18·757 |
  |   45  | 1·0899 | 17·854  | 18·349 |
  |   44  | 1·0879 | 17·457  | 17·941 |
  |   43  | 1·0859 | 17·060  | 17·534 |
  |   42  | 1·0838 | 16·664  | 17·126 |
  |   41  | 1·0818 | 16·267  | 16·718 |
  |   40  | 1·0798 | 15·870  | 16·310 |
  |   39  | 1·0778 | 15·474  | 15·902 |
  |   38  | 1·0758 | 15·077  | 15·494 |
  |   37  | 1·0738 | 14·680  | 15·087 |
  |   36  | 1·0718 | 14·284  | 14·679 |
  |   35  | 1·0697 | 13·887  | 14·271 |
  |   34  | 1·0677 | 13·490  | 13·863 |
  |   33  | 1·0657 | 13·094  | 13·456 |
  |   32  | 1·0637 | 12·697  | 13·049 |
  |   31  | 1·0617 | 12·300  | 12·641 |
  |   30  | 1·0597 | 11·903  | 12·233 |
  |   29  | 1·0577 | 11·506  | 11·825 |
  |   28  | 1·0557 | 11·109  | 11·418 |
  |   27  | 1·0537 | 10·712  | 11·010 |
  |   26  | 1·0517 | 10·316  | 10·602 |
  |   25  | 1·0497 |  9·919  | 10·194 |
  |   24  | 1·0477 |  9·522  |  9·786 |
  |   23  | 1·0457 |  9·126  |  9·379 |
  |   22  | 1·0437 |  8·729  |  8·971 |
  |   21  | 1·0417 |  8·332  |  8·563 |
  |   20  | 1·0397 |  7·935  |  8·155 |
  |   19  | 1·0377 |  7·538  |  7·747 |
  |   18  | 1·0357 |  7·141  |  7·340 |
  |   17  | 1·0337 |  6·745  |  6·932 |
  |   16  | 1·0318 |  6·348  |  6·524 |
  |   15  | 1·0298 |  5·951  |  6·116 |
  |   14  | 1·0279 |  5·554  |  5·709 |
  |   13  | 1·0259 |  5·158  |  5·301 |
  |   12  | 1·0239 |  4·762  |  4·893 |
  |   11  | 1·0220 |  4·365  |  4·486 |
  |   10  | 1·0200 |  3·968  |  4·078 |
  |    9  | 1·0180 |  3·571  |  3·670 |
  |    8  | 1·0160 |  3·174  |  3·262 |
  |    7  | 1·0140 |  2·778  |  2·854 |
  |    6  | 1·0120 |  2·381  |  2·447 |
  |    5  | 1·0100 |  1·984  |  2·039 |
  |    4  | 1·0080 |  1·588  |  1·631 |
  |    3  | 1·0060 |  1·191  |  1·224 |
  |    2  | 1·0040 |  0·795  |  0·816 |
  |    1  | 1·0020 |  0·397  |  0·408 |
  +-------+--------+---------+--------+


MURIATES were, till the great chemical era of Sir H. Davy’s researches
upon chlorine, considered to be compounds of an undecompounded acid, the
muriatic, with the different bases; but he proved them to be in reality
compounds of chlorine with the metals. They are all, however, still
known in commerce by their former appellation. The only muriates much
used in the manufactures are, _Muriate of ammonia_, or SAL AMMONIAC;
_muriated peroxide of mercury_, MERCURY, _bichloride of_; _muriate of
soda_, or _chloride of sodium_, see SALT; _muriate of tin_, see
CALICO-PRINTING and TIN.


MUSK (_Musc_, Fr.; _Moschus_, Germ.), is a peculiar aromatic substance,
found in a sac between the navel and the parts of generation of a small
male quadruped of the deer kind, called by Linnæus, Moschus moschiferus,
which inhabits Tonquin and Thibet. The colour of musk is blackish-brown;
it is lumpy or granular, somewhat like dried blood, with which
substance, indeed, it is often adulterated. The intensity of its smell
is almost the only criterion of its genuineness. When thoroughly dried
it becomes nearly scentless; but it recovers its odour when slightly
moistened with water of ammonia. The Tonquin musk is most esteemed. It
comes to us in small bags covered with a reddish-brown hair; the bag of
the Thibet musk is covered with a silver-gray hair. All the analyses of
musk hitherto made, teach little or nothing concerning its active or
essential constituent. It is used in medicines, and is an ingredient in
a great many perfumes.


MUSLIN, is a fine cotton fabric, used for ladies’ robes; which is worn
either white, dyed, or printed.


MUST, is the sweet juice of the grape.


MUSTARD (_Moutarde_, Fr.; _Senf_, Germ.); is a plant which yields the
well-known seed used as a condiment to food. M. Lenormand gives the
following prescription for preparing mustard for the table.

With 2 pounds of very fine flour of mustard, mix half an ounce of each
of the following fresh plants; parsley, chervil, celery, and tarragon,
along with a clove of garlic, and twelve salt anchovies, all well
minced. The whole is to be triturated with the flour of mustard till the
mixture becomes uniform. A little grape-must or sugar is to be added, to
give the requisite sweetness; then one ounce of salt, with sufficient
water to form a thinnish paste by rubbing in a mortar. With this paste
the mustard pots being nearly filled, a redhot poker is to be thrust
down into the contents of each, which removes (it is said) some of the
acrimony of the mustard, and evaporates a little water, so as to make
room for pouring a little vinegar upon the surface of the paste. Such
table mustard not only keeps perfectly well, but improves with age.

The mode of preparing table mustard patented by M. Soyés, consisted in
steeping mustard seed in twice its bulk of weak wood vinegar for eight
days, then grinding the whole into paste in a mill, putting it into
pots, and thrusting a redhot poker into each of them.


MUTAGE, is a process used in the south of France to arrest the progress
of fermentation in the must of the grape. It consists either in
diffusing sulphurous acid, from burning sulphur matches in the cask
containing the must, or in adding a little sulphite (not sulphate) of
lime to it. The last is the best process. See FERMENTATION.


MYRICINE, is a vegetable principle which constitutes from 20 to 30 per
cent. of the weight of bees-wax, being the residuum from the solvent
action of alcohol upon that substance. It is a grayish-white solid,
which may be vaporized almost without alteration.


MYRRH, is a gum-resin, which occurs in tears of different sizes; they
are reddish-brown, semi-transparent, brittle, of a shining fracture,
appear as if greasy under the pestle, they have a very acrid and bitter
taste, and a strong, not disagreeable, smell. Myrrh flows from the
incisions of a tree not well known, which grows in Arabia and Abyssinia,
supposed to be a species of _amyris_ or _mimosa_. It consists of resin
and gum in proportions stated by Pelletier at 31 of the former and 66 of
the latter; but by Braconnot, at 23 and 77. It is used only in medicine.




N.


NACARAT, is a term derived from the Spanish word _nacar_, which
signifies mother of pearl; and is applied to a pale red colour, with an
orange cast. See CALICO-PRINTING. The _nacarat_ of Portugal or _Bezetta_
is a crape or fine linen fabric, dyed fugitively of the above tint,
which ladies rub upon their countenances to give them a roseate hue. The
Turks of Constantinople manufacture the brightest red crapes of this
kind. See ROUGE.


NAILS, MANUFACTURE OF. (_Clou_, Fr.; _Nagel_, Germ.)

The forging of nails was till of late years a handicraft operation, and
therefore belonged to a book of trades, rather than to a dictionary of
arts. But several combinations of machinery have been recently employed,
under the protection of patents, for making these useful implements,
with little or no aid of the human hand; and these deserve to be
noticed, on account both of their ingenuity and importance.

As nails are objects of prodigious consumption in building their
block-houses, the citizens of the United States very early turned their
mechanical genius to good account in the construction of various
machines for making them. So long since as the year 1810, it appears,
from the report of the secretary of their treasury, that they possessed
a machine which performed the cutting and heading at one operation, with
such rapidity that it could turn out upwards of 100 nails per minute.
“Twenty years ago,” says the secretary of the state of Massachusetts, in
that report, “some men, then unknown, and then in obscurity, began by
cutting slices out of old hoops, and, by a common vice griping these
pieces, headed them with several strokes of the hammer. By progressive
improvements, slitting-mills were built, and the shears and the heading
tools were perfected; yet much labour and expense were requisite to make
nails. In a little time Jacob Perkins, Jonathan Ellis, and a few others,
put into execution the thought of cutting and of heading nails by water
power; but, being more intent upon their machinery than upon their
pecuniary affairs, they were unable to prosecute the business. At
different times other men have spent fortunes in improvements, and it
may be said with truth that more than one million of dollars has been
expended; but at length these joint efforts are crowned with complete
success, and we are now able to manufacture, at about one-third of the
expense that wrought nails can be manufactured for, nails which are
superior to them for at least three-fourths of the purposes to which
nails are applied, and for most of those purposes they are full as good.
The machines made use of by Odiorne, those invented by Jonathan Ellis,
and a few others, present very fine specimens of American genius.

“To northern carpenters, it is well known that in almost all instances
it is unnecessary to bore a hole before driving a cut nail; all that is
requisite is, to place the cutting edge of the nail across the grain of
the wood; it is also true, that cut nails will hold better in the wood.
These qualities are, in some rough building works, worth twenty _per
cent._ of the value of the article, which is equal to the whole expense
of manufacturing. For sheathing and drawing, cut nails are full as good
as wrought nails; only in one respect are the best wrought nails a
little superior to cut nails, and that is where it is necessary they
should be clenched. The manufacture of cut nails was born in our
country, and has advanced, within its bosom, through all the various
stages of infancy to manhood; and no doubt we shall soon be able, by
receiving proper encouragement, to render them superior to wrought nails
in every particular.

“The principal business of rolling and slitting-mills, is rolling nail
plates; they also serve to make nail rods, hoops, tires, sheet iron, and
sheet copper. In this State we have not less than twelve.

“These mills could roll and slit 7000 tons of iron a year; they now, it
is presumed, roll and slit each year about 3500 tons, 2400 tons of
which, probably, are cut up into nails and brads, of such a quality that
they are good substitutes for hammered nails, and, in fact, have the
preference with most people, for the following reasons; viz., on account
of the sharp corner and true taper with which cut nails are formed; they
may be driven into harder wood without bending or breaking, or hazard of
splitting the wood, by which the labour of boring is saved, the nail one
way being of the same breadth or thickness from head to point.”

Since the year 1820, the following patents have been obtained in England
for making nails; many of them of American origin:--

_Alexander Law_, September, 1821, for nails and bolts for ships’
fastenings, made in a twisted form, by hand labour.

_Glascott and Mitchell_, December, 1823, for ship nails with rounded
heads, by hand labour.

_Wilks and Ecroyd_, November, 1825, for an engine for cutting wedge-form
pieces from plates.

_Ledsom and Jones_, December 11, 1827, for machinery for cutting brads
and sprigs from plates; it does not form heads.

The first nail apparatus to which I shall particularly advert, is due to
Dr. Church; it was patented in his absence by his correspondent, Mr.
Thomas Tyndall, of Birmingham, in December, 1827. It consists of two
parts; the first is a mode of forming nails, and the shafts of screws,
by pinching or pressing ignited rods of iron between indented rollers;
the second produces the threads on the shafts of the screws previously
pressed. The metallic rods, by being passed between a pair of rollers,
are rudely shaped, and then cut asunder between a pair of shears; after
which they are pointed and headed, or otherwise brought to their
finished forms, by the agency of dies placed in a revolving cylinder.
The several parts of the mechanism are worked by toothed wheels, cams,
and levers. The second part of Dr. Church’s invention consists of a
mechanism for cutting the threads of screws to any degree of obliquity
or form.[35]

  [35] For further details, see Newton’s Journal, 2nd series, vol. iii.
  p. 184.

Mr. L. W. Wright’s (American) apparatus should have been mentioned
before the preceding, as the patent for it was sealed in March of the
same year; though an amended patent was obtained in September, 1828. Its
object was to form metal screws for wood. I have seen the machinery, but
consider it much too complex to be described in the present work.

Mr. Edward Hancorne, of Skinner street, London, nail manufacturer,
obtained a patent in October, 1828 for a nail-making machine, of which a
brief description may give my readers a conception of this kind of
manufacture. Its principles are similar to those of Dr. Church’s more
elaborate apparatus.

[Illustration: 749]

The rods or bars having been prepared in the usual way, either by
rolling or hammering, or by cutting from sheets or plates of iron,
called slitting, are then to be made redhot, and in that state passed
through the following machine, whereby they are at once cut into
suitable lengths, pressed into wedge forms for pointing at the one end,
and stamped at the other end to produce the head. A longitudinal view of
the machine is shown in _fig._ 749. A strong iron frame-work, of which
one side is shown at _a a_, supports the whole of the mechanism. _b_ is
a table capable of sliding to and fro horizontally. Upon this table are
the clamps, which lay hold of the sides of the rod as it advances; as
also the shears which cut the rod into nail lengths.

These clamps or holders consist of a fixed piece and a movable piece;
the latter being brought into action by a lever. The rod or bar of iron
shown at _c_, having been made redhot, is introduced into the machine by
sliding it forward upon the table _b_, when the table is in its most
advanced position; rotatory motion is then given to the crank shaft _d_,
by means of a band passing round the rigger pulley _e_, which causes the
table _b_ to be drawn back by the crank rod _f_: and as the table
recedes, the horizontal lever is acted upon, which closes the clamps. By
these means the clamps take fast hold of the sides of the heated rod,
and draw it forward, when the movable chap of the shears, also acted
upon by a lever, slides laterally, and cuts off the end of the rod held
by the clamps: the piece thus separated is destined to form one nail.

Suppose that the nail placed at _g_, having been thus brought into the
machine and cut off, is held between clamps, which press it sideways
(these clamps are not visible in this view); in this state it is ready
to be headed and pointed.

The _header_ is a steel die _h_, which is to be pressed up against the
end of the nail by a cam _i_, upon the crank-shaft; which cam, at this
period of the operation, acts against the end of a rod _k_, forming a
continuation of the die _h_, and forces up the die, thus compressing the
metal into the shape of a nail-head.

The _pointing_ is performed by two rolling snail pieces or spirals _l_,
_l_. These pieces are somewhat broader than the breadth of the nail;
they turn upon axles in the side frames. As the table _b_ advances, the
racks _m_, on the edge of this table, take into the toothed segments
_n_, _n_, upon the axles of the spirals, and cause them to turn round.

These spirals pinch the nail at first close under its head with very
little force; but as they turn round, the longer radius of the spiral
comes into operation upon the nail, so as to press its substance very
strongly, and squeeze it into a wedge form. Thus the nail is completed,
and is immediately discharged from the clamps or holders. The carriage
is then again by the rotation of the crank-shaft, which brings another
portion of the rod _c_ forward, cuts it off, and then forms it into a
nail.

_Richard Prosser_, July, 1831, for making tacks for ornamental
furniture, by soldering or wedging the spike into the head. This also is
the invention of Dr. Church.

_Dr. William Church_, February, 1832, for improvements in machinery for
making nails. These consist, first, in apparatus for forming rods, bars,
or plates of iron, or other metals; secondly, in apparatus for
converting the rods, &c., into nails; thirdly, in improvements upon
Prosser’s patent. The machinery consists in laminating rollers, and
compressing dies.

The method of forming the rods from which the nails are to be made, is
very advantageous. It consists in passing the bar or plate iron through
pressing rollers, which have indentations upon the peripheries of one or
both of them, so as to form the bar or plate into the required shape for
the rods, which may be afterwards separated into rods of any desired
breadth, by common slitting rollers.

The principal object of rolling the rods into these wedge forms, is to
measure out a quantity of metal duly proportioned to the required
thickness or strength of the nail in its several parts; which quantity
corresponds to the indentations of the rollers.

_Thomas John Fuller_, February 27, 1834, for an improved apparatus for
making square-pointed, and also flat-pointed nails. He claims as his
invention, the application of vertical and horizontal hammers (mounted
in his machine) combined for the purpose of tapering and forming the
points of the nails; which, being made to act alternately, resemble hand
work, and are therefore not so apt to injure the fibrous texture of the
iron, he imagines, as the rolling machinery is. He finishes the points
by rollers.

_Miles Berry_, February 19, 1834, for machinery for forming metal into
bolts, rivets, nails and other articles; being a communication from a
foreigner residing abroad. He employs in his machine holding chaps,
heading dies, toggle joints, cams, &c., mechanisms apparently skilfully
contrived, but too complex for admission under the article _nail_ in
this volume.

_William Southwood Stocker_, July, 1836. This is a machine apparently of
American parentage, as it has the same set of features as the old
American mechanisms of Perkins and Dyer, at the Britannia Nailworks,
Birmingham, and all the other American machines since described, for
pressing metal into the forms of nails, pins, screw-shafts, rivets, &c.;
for example, it possesses pressers or hammers for squeezing the rods of
metal, and forming the shanks, which are all worked by a rotatory
action; cutters for separating the appropriate lengths, and dies for
forming the heads by compression, also actuated by revolving cams or
cranks.

Mr. Stocker intends, in fact, to effect the same sorts of operations by
automatic mechanisms as are usually performed by the hands of a
nail-maker with his hammer and anvil; viz., the shaping of a nail from a
heated rod of iron, cutting it off at the proper length, and then
compressing the end of the metal into the form of the head. His machine
may be said to consist of two parts, connected in the same frame; the
one for shaping the shank of the nail, the other for cutting it off and
heading it. The frame consists of a strong table to bear the machinery.
Two pairs of hammers, formed as levers, the one pair made to approach
each other by horizontal movements, the other pair by vertical
movements, are the implements by which a portion at the end of a redhot
rod of iron is beaten or pressed into the wedge-like shape of the shaft
of a nail. This having been done, and the rod being still hot, is
withdrawn from the beaters, and placed in the other part of the machine,
consisting of a pair of jaws like those of a vice, which pinch the shank
of the nail and hold it fast. A cutter upon the side of a wheel now
comes round, and, by acting as the moving chap of a pair of shears, cuts
the nail off from the rod. The nail shank being still firmly held in the
jaws of the vice, with a portion of its end projecting outwardly, the
heading die is slidden laterally until it comes opposite to the end of
the nail; the dye is then projected forward with great force, for the
purpose of what is termed upsetting the metal at the projecting end of
the nail, and thereby blocking out the head.

A main shaft, driven by a band and rigger as usual, brings, as it
revolves, a cam into operation upon a lever which carries a double
inclined plane or wedge in its front or acting part. This wedge being by
the rotatory cam projected forwards between the tails of one of the
pairs of hammers, causes the faces of these hammers to approach each
other, and to beat or press the redhot iron introduced between them, so
as to flatten it upon two opposite sides. The rotatory cam passing
round, the wedge lever is relieved, when springs instantly throw back
the hammers; another cam and wedge-lever now brings the second pair of
hammers to act upon the other two sides of the nail in a similar way.
This is repeated several times, until the end of the redhot iron rod,
gradually advanced by the hands of the workman, has assumed the desired
form, that is, has received the bevel and point of the intended nail.

The rod is then withdrawn from between the hammers, and in its heated
state is introduced between the jaws of the holders, for cutting off and
finishing the nail. A bevel pinion upon the end of the main shaft, takes
into and drives a wheel upon a transverse shaft, which carries a cam
that works the lever of the holding jaws. The end of the rod being so
held in the jaws or vice, a cutter at the side of a wheel upon the
transverse shaft separates, as it revolves, the nail from the end of the
rod, leaving the nail firmly held by the jaws. By means of a cam, the
heading die is now slidden laterally opposite to the end of the nail in
the holding jaws, and by another cam, upon the main shaft, the die is
forced forward, which compresses the end of the nail, and spreads out
the nail into the form of a head. As the main shaft continues to
revolve, the cams pass away, and allow the spring to throw the jaws of
the vice open, when the nails fall out; but to guard against the chance
of a nail sticking in the jaws, a picker is provided, which pushes the
nail out as soon as it is finished.

In order to produce round shafts, as for screw blanks, bolts, or rivets,
the faces of the hammers, and the dies for heading, must be made with
suitable concavities.

In 1835, 5,180, and in 1836, 5,580 tons of iron nails were exported from
the United Kingdom.


NANKIN, is a peculiarly coloured cotton cloth, originally manufactured
in the above named antient capital of China, from a native cotton of a
brown yellow hue. Nankin cloth has been long imitated in perfection by
our own manufacturers; and is now exported in considerable quantities
from England to Canton. The following is the process for dyeing calico a
nankin colour.

1. Take 300 pounds of cotton yarn in hanks, being the quantity which
four workmen can dye in a day. The yarn for the warp may be about No.
27’s, and that for the weft 23’s or 24’s.

2. For _aluming_ that quantity, take 10 pounds of saturated alum, free
from iron (see MORDANT); divide this into two portions; dissolve the
first by itself in hot water, so as to form a solution, of spec. grav.
1° Baumé. The second portion is to be reserved for the galling bath.

3. _Galling_, is given with about 80 pounds of oak bark finely ground.
This bark may serve for two quantities, if it be applied a little longer
the second time.

4. Take 30 pounds of fresh slaked quicklime, and form with it a large
bath of lime-water.

5. _Nitro-muriate of tin._ For the last bath, 10 or 12 pounds of
solution of tin are used, which is prepared as follows:

Take 10 pounds of strong nitric acid, and dilute with pure water till
its specific gravity be 26° B. Dissolve in it 4633 grains (10-1/2 oz.
avoird.) of sal ammoniac, and 3 oz. of nitre. Into this solvent,
contained in a bottle set in cold water, introduce successively, in very
small portions, 28 ounces of grain-tin granulated. This solution, when
made, must be kept in a well stoppered bottle.

Three coppers are required, one round, about five feet in diameter, and
32 inches deep, for scouring the cotton; 2. two rectangular coppers
tinned inside, each 5 feet long and 20 inches deep. Two boxes or
cisterns of white wood are to be provided, the one for the lime-water
bath, and the other for the solution of tin, each about 7 feet long, 32
inches wide, and 14 inches deep; they are set upon a platform 28 inches
high. In the middle between these two chests, a plank is fixed, mounted
with twenty-two pegs for wringing the hanks upon, as they are taken out
of the bath.

6. _Aluming._ After the cotton yarn has been scoured with water, in the
round copper, by being boiled in successive portions of 100 pounds, it
must be winced in one of the square tinned coppers, containing two
pounds of alum dissolved in 96 gallons of water, at a temperature of
165° F. It is to be then drained over the copper, exposed for some time
upon the grass, rinsed in clear water, and wrung.

7. The _galling_. Having filled four-fifths of the second square copper
with water, 40 pounds of ground oak bark are to be introduced, tied up
in a bag of open canvas, and boiled for two hours. The bag being
withdrawn, the cotton yarn is to be winced through the boiling tan bath
for a quarter of an hour. While the yarn is set to drain above the bath,
28 ounces of alum are to be dissolved in it, and the yarn being once
more winced through it for a quarter of an hour, is then taken out,
drained, wrung, and exposed to the air. It has now acquired a deep but
rather dull yellowish colour, and is ready without washing for the next
process. Bablah may be substituted for oak bark with advantage.

8. The _liming_. Into the cistern filled with fresh made lime-water, the
hanks of cotton yarn suspended upon a series of wooden rods, are to be
dipped freely three times in rapid succession; then each hank is to be
separately moved by hand through the lime bath, till the desired
carmelite shade appear. A weak soda lye may be used instead of lime
water.

9. The _brightening_, is given by passing the above hanks, after
squeezing, rinsing, and airing them, through a dilute bath of solution
of tin. The colour thus produced is said to resemble perfectly the
nankin of China.

Another kind of nankeen colour is given by oxide of iron, precipitated
upon the fibre of the cloth, from a solution of the sulphate, by a
solution of soda. See CALICO-PRINTING.


NAPLES YELLOW (_Jaune minéral_, Fr.; _Neapelgelb_, Germ.); is a fine
yellow pigment, called _giallolino_, in Italy, where it has been long
prepared by a secret process; for few of the recipes which have been
published produce a good colour. It is employed not only in oil
painting, but also for porcelain and enamel. It has a fresh, brilliant,
rich hue, but is apt to be very unequal in different samples.

The following prescription has been confidently recommended. Twelve
parts of metallic antimony are to be calcined in a reverberatory
furnace, along with eight parts of red lead, and four parts of oxide of
zinc. These mixed oxides being well rubbed together, are to be fused;
and the fused mass is to be triturated and elutriated into a fine
powder. Chromate of lead has in a great measure superseded Naples
yellow.


NAPHTHA, or ROCK-OIL (_Huile pétrole_, Fr.; _Steinöl_, Germ.); the
Seneca oil of North America, is an ethereous or volatile oil, which is
generated within the crust of the earth, and issues in many different
localities. The colourless kind, called naphtha, occurs at Baku, near
the Caspian Sea, where the vapours which it exhales are kindled, and the
flame is applied to domestic and other economical purposes. Wells are
also dug in that neighbourhood, in which the naphtha is collected.
Similar petroleum wells exist in the territory of the Birmans, at
Yananghoung, upon the river Erawaddy, 80 hours’ journey north-east of
Pegu, where no less than 520 such springs issue from a pale blue clay,
soaked with oil, which rests upon roofing slate. Under the slate is
coal containing much pyrites. Each spring yields annually 173 casks of
950 pounds each. Petroleum is also found at Amiano in the duchy of
Parma, at Saint Zibio in the grand duchy of Modena, at Neufchatel in
Switzerland, at Clermont in France, upon some points of the banks of the
Iser, at Gabian, a village near Bezières, at Tegernsee in Bavaria, at
Val di Noto in Sicily, in Zante, Gallicia, Wallachia, Trinidad,
Barbadoes, the United States, Rangoon, near Ava, &c. What is found in
the market comes mostly from Trinidad. The city of Parma is lighted with
naphtha.

The Persian rock-oil is colourless, limpid, very fluid, of a penetrating
odour, a hot taste, and a specific gravity of 0·753; it is said to boil
at 160° F. The common petroleum has a reddish-yellow colour, which
appears blue by reflected light, is transparent, has a spec. grav. of
0·836, and contains, according to Unverdorben, several oils of different
degrees of volatility, a little oleine and stearine, resin, with a brown
indifferent substance held in solution. By repeated rectifications its
density may be reduced to 0·758 at 60° F. Native naphtha, of specific
gravity 0·749, is said by some to boil at 201° F. The condensed vapour
consists of 85·05 carbon, and 14·30 hydrogen.

The naphtha procured by distilling the coal oil of the gas works, is of
specific gravity 0·857, boils at 316° F., and consists of, carbon 83·04,
hydrogen 12·31, and oxygen 4·65, by my experiments.

Rock-oil is very inflammable; its vapour forms with oxygen gas a mixture
which violently detonates, and produces water and carbonic acid gas. It
does not unite with water, but it imparts a peculiar smell and taste to
it; it combines in all proportions with strong alcohol, with ether and
oils, both essential and unctuous; it dissolves sulphur, phosphorus,
iodine, camphor, most of the resins, wax, fats, and softens caoutchouc
into a glairy varnish. When adulterated with oil of turpentine, it
becomes thick and reddish brown, on being agitated in contact with
strong sulphuric acid. A very fine black pigment may be prepared from
the soot of petroleum lamps.


NAPHTHALINE, is a peculiar white crystallizable substance, which may be
extracted by distillation from coal tar. It has a pungent aromatic smell
and taste, and a specific gravity of 1·048. It is a solid bicarburet of
hydrogen, consisting, by my experiments, of 92·9 of carbon, and 7·1 of
hydrogen. It has not been applied to any use.


NATRON, is the name of the native sesquicarbonate of soda, which occurs
in Egypt, in the west of the Delta; also in the neighbourhood of Fessan,
in the province of Sukena in Northern Africa, where it exists under the
name of _Trona_, crystallized along with sulphate of soda; near Smyrna,
in Tartary, Siberia, Hungary, Hindostan, and Mexico. In the last
country, there are several natron lakes, a little to the north of
Zucatecas, as well as in many other provinces. In Columbia, 48 miles
from Merida, native mineral natron is dug up from the bottom of lakes in
large quantities, under the name of _Urao_.

According to Laugier, the Egyptian natron consists of carbonate of soda
22·44, sulphate of soda 18·35, muriate of soda 38·64, water 14·0,
insoluble matter 6·0. Trona is composed of carbonate of soda 65·75,
sulphate of soda 7·65, muriate of soda 2·63, water 24, insoluble matter
1. The sesquicarbonate may be artificially prepared by boiling for a
short time a solution of the bicarbonate.


NEALING. See ANNEALING.


NEB-NEB, is the East Indian name of Bablah.


NEEDLE MANUFACTURE. When we consider the simplicity, smallness, and
moderate price of a needle, we would be naturally led to suppose that
this little instrument requires neither much labour nor complicated
manipulations in its construction; but when we learn that every sewing
needle, however inconsiderable its size, passes through the hands of 120
different operatives, before it is ready for sale, we cannot fail to be
surprised.

The best steel, reduced by a wire-drawing machine to the suitable
diameter, is the material of which needles are formed. It is brought in
bundles to the needle factory, and carefully examined. For this purpose,
the ends of a few wires in each bundle are cut off, ignited, and
hardened by plunging them into cold water. They are now snapped between
the fingers, in order to judge of their quality; the bundles belonging
to the most brittle wires are set aside, to be employed in making a
peculiar kind of needles.

After the quality of the steel wire has been properly ascertained, it is
calibred by means of a gauge, to see if it be equally thick and round
throughout, for which purpose merely some of the coils of the bundle of
wires are tried. Those that are too thick are returned to the
wire-drawer, or set apart for another size of needles.

[Illustration: 750 751]

The first operation, properly speaking, of the needle factory, is
unwinding the bundles of wires. With this view the operative places the
coil upon a somewhat conical reel, _fig._ 750., whereon he may fix it at
a height proportioned to its diameter. The wire is wound off upon a
wheel B, formed of eight equal arms, placed at equal distances round a
nave, which is supported by a polished round axle of iron, made fast to
a strong upright C, fixed to the floor of the workshop. Each of the arms
is 54 inches long; and one of them D, consists of two parts; of an
upper part, which bears the cross bar E, to which the wire is applied;
and of an under part, connected with the nave. The part E slides in a
slot in the fixed part F, and is made fast to it by a peg at a proper
height for placing the ends of all the spokes in the circumference of a
circle. This arrangement is necessary, to permit the wire to be readily
taken off the reel, after being wound tight round its eight branches.
The peg is then removed, the branch pushed down, and the coil of wire
released. _Fig._ 751. shows the wheel in profile. It is driven by the
winch-handle G.

[Illustration: 752 753]

The new made coil is cut in two points diametrically opposite, either by
hand shears, of which one of the branches is fixed in a block by a bolt
and a nut, as shown in _fig._ 752., or by means of the mechanical
shears, represented in _fig._ 753. The crank A is moved by a hydraulic
wheel, or steam power, and rises and falls alternately. The extremity of
this crank enters into a mortise cut in the arm B of a bent lever B G C,
and is made fast to it by a bolt. An iron rod D F, hinged at one of its
extremities to the end of the arm C, and at the other to the tail of the
shears or chisel E, forces it to open and shut alternately. The
operative placed upon the floor under F presents the coil to the action
of the shears, which cut it into two bundles, composed each of 90 or 100
wires, upwards of 8 feet long. The chisel strikes 21 blows in the
minute.

These bundles are afterwards cut with the same shears into the desired
needle lengths, these being regulated by the diameter. For this purpose
the wires are put into a semi-cylinder of the proper length, with their
ends at the bottom of it, and are all cut across by this gauge. The
wires, thus cut, are deposited into a box placed alongside of the
workman.

[Illustration: 754 755 756 757]

Two successive incisions are required to cut 100 wires, the third is
lost; hence the shears, striking 21 blows in a minute, cut in 10 hours
fully 400,000 ends of steel wire, which produce more than 800,000
needles. The wires thus cut are more or less bent, and require to be
straightened. This operation is executed with great promptitude, by
means of an appropriate instrument. In two strong iron rings A B, _fig._
754., of which one is shown in front view at C, 5000 or 6000 wires,
closely packed together, are put; and the bundle is placed upon a flat
smooth bench L M, _fig._ 757., covered with a cast-iron plate D E, in
which there are two grooves of sufficient depth for receiving the two
ring bundles of wire, or two openings like the rule F, _fig._ 757., upon
which is placed the open iron rule F, shown in front in _fig._ 756. upon
a greater scale. The two rings must be carefully set in the intervals of
the rule. By making this rule come and go five or six times with such
pressure upon the bundles of wires as causes it to turn upon its axis,
all the wires are straightened almost instantaneously.

The construction of the machine, represented in _fig._ 757., may require
explanation. It consists of a frame in the form of a table, of which L M
is the top; the cast-iron plate D E is inserted solidly into it. Above
the table, seen in _fig._ 755. in plan, there are two uprights C H, to
support the cross bar A A, which is held in forks cut out in the top of
each of the two uprights. This cross bar A A, enters tightly into a
mortise cut in the swing piece N, at the point N, where it is fixed by a
strong pin, so that the horizontal traverse communicated to the cross
bar A A affects at the same time the swing piece N. At the bottom of
this piece is fixed, as shown in the figure, the open rule F, seen upon
a greater scale in _fig._ 756.

When the workman wishes to introduce the bundle B, he raises, by means
of two chains I K, _fig._ 757., and the lever G O, the swing piece and
the cross bar. For this purpose he draws down the chain I; and when he
has placed the bundle properly, so that the two rings enter into the
groove E D, _fig._ 755., he allows the swing piece to fall back, so that
the same rings enter the open clefts of the rule F; he then seizes one
of the projecting arms of the cross bar A, alternately pulling and
pushing it in the horizontal direction, whereby he effects, as already
stated, the straightening of the wires.

[Illustration: 758]

The wires are now taken to the pointing-tools, which usually consist of
about 30 grindstones arranged in two rows, driven by a water-wheel. Each
stone is about 18 inches in diameter, and 4 inches thick. As they
revolve with great velocity, and are liable to fly in pieces, they are
partially encased by iron plates, having a proper slit in them to admit
of the application of the wires. The workman seated in front of the
grindstone, seizes 50 or 60 wires between the thumb and forefinger of
his right hand, and directs one end of the bundle to the stone. By means
of a bit of stout leather called a thumb-piece, of which A, _fig._ 758.,
represents the profile, and B the plan, the workman presses the wires,
and turns them about with his forefinger, giving them such a rotatory
motion as to make their points conical. This operation, which is called
_roughing down_, is dry grinding; because, if water were made use of,
the points of the needles would be rapidly rusted. It has been observed
long ago, that the siliceous and steel dust thrown off by the stones,
was injurious to the eyes and lungs of the grinders; and many methods
have been proposed for preventing its bad effects. The machine invented
for this purpose by Mr. Prior, for which the Society of Arts voted a
premium, deserves to be generally known.

[Illustration: 759]

A A, _fig._ 759., is the fly-wheel of an ordinary lathe, round which the
endless cord B B passes, and embraces the pulley C, mounted upon the
axle of the grindstone D. The flywheel is supported by a strong frame E
E, and may be turned by a winch-handle, as usual, or by mechanical
power. In the needle factories, the pointing-shops are in general very
large, and contain several grindstones running on the same long
horizontal shaft, placed near the floor of the apartment, and driven by
water or steam power. One of the extremities of the shaft of the wheel A
has a kneed or bent winch F, which by means of an intermediate crank G
G, sets in action a double bellows H I, with a continuous blast,
consisting of the air feeder H below, and the air regulator I above. The
first is composed of two flaps, one of them _a a_, being fast and
attached to the floor, and the other _e e_, moving with a hinge-joint;
both being joined by strong leather nailed to their edges. This flap has
a tail _g_, of which the end is forked to receive the end of the crank
G. Both flaps are perforated with openings furnished with valves for the
admission of the air, which is thence driven into a horizontal pipe K,
placed beneath the floor of the workshop, and may be afterwards directed
in an uninterrupted blast upon the grindstone, by means of the tin tubes
N O O, which embrace it, and have longitudinal slits in them. A brass
socket is supposed to be fixed upon the ground; it communicates with the
pipe K, by means of a small copper tube, into which one of the
extremities of the pipe N is fitted; the other is supported by the point
of a screw Q, and moves round it as a pivot, so as to allow the two
upright branches O O, to be placed at the same distance from the
grindstone. These branches are soldered to the horizontal pipe N, and
connected at their top by the tube P.

The wind which escapes through the slits of these pipes, blows upon the
grindstone, and carries off its dust into a conduit R, _fig._ 759.,
which may be extended to S, beyond the wall of the building, or bent at
right angles, as at T, to receive the conduits of the other grindstones
of the factory.

A safety valve J, placed in an orifice formed in the regulator flap I,
is kept shut by a spiral spring of strong iron wire. It opens to allow
the superfluous air to escape, when, by the rising of the bellows, the
tail L presses upon a small piece of wood, and thereby prevents their
being injured.

[Illustration: 760]

The wires thus pointed at both ends are transferred to the first
workshop, and cut in two, to form two needles, so that all of one
quality may be of equal length. For each sort a small instrument, _fig._
760., is employed, being a copper plate nearly square, having a turned
up edge only upon two of its sides; the one of which is intended to
receive all the points, and the other to resist the pressure of the
shears. In this small tool a certain number of wires are put with their
points in contact with the border, and they are cut together flush with
the plate by means of the shears, _fig._ 752., which are moved by the
knee of the workman. The remainder of the wires are then laid upon the
same copper or brass tool, and are cut also even; there being a trifling
waste in this operation. The pieces of wire out of which two needles are
formed, are always left a little too long, as the pointer can never hit
exact uniformity in his work.

These pointed wires are laid parallel to each other in little wooden
boxes, and transferred to the head-flattener. This workman, seated at a
table with a block of steel before him, about 3 inches cube, seizes in
his left hand 20 or 25 needles, between his finger and thumb, spreading
them out like a fan, with the points under the thumb, and the heads
projecting; he lays these heads upon the steel block, and with a small
flat-faced hammer strikes successive blows upon all the heads, so as to
flatten each in an instant. He then arranges them in a box with the
points turned the same way.

The flatted heads have become hardened by the blow of the hammer; when
annealed by heating and slow cooling, they are handed to the _piercer_.
This is commonly a child, who laying the head upon a block of steel, and
applying the point of a small punch to it, pierces the eye with a smart
tap of a hammer, applied first upon the one side, and then exactly
opposite upon the other.

Another child trims the eyes, which he does by laying the needle upon a
lump of lead, and driving a proper punch through its eye; then laying it
sidewise upon a flat piece of steel, with the punch sticking in it, he
gives it a tap on each side with his hammer, and causes the eye to take
the shape of the punch. The operation of piercing and trimming the eyes,
is performed by clever children with astonishing rapidity; who become so
dexterous as to pierce with their punch a human hair, and thread it with
another, for the amusement of visitors.

[Illustration: 761]

The next operative makes the groove at the eye, and rounds the head. He
fixes the needle in pincers, _fig._ 761., so that the eye corresponds to
their flat side; he then rests the head of the needle in an angular
groove, cut in a piece of hard wood fixed in a vice, with the eye in an
upright position. He now forms the groove with a single stroke of a
small file, dexterously applied, first to the one side of the needle,
and then to the other. He next rounds and smooths the head with a small
flat file. Having finished, he opens the pincers, throws the needle upon
the bench, and puts another in its place. A still more expeditious
method of making the grooves and finishing the heads has been long used
in most English factories. A small ram is so mounted as to be made to
rise and fall by a pedal lever, so that the child works the tool with
his foot; in the same way as the heads of pins are fixed. A small die of
tempered steel bears the form of the one channel or groove, another
similar die, that of the other, both being in relief; these being worked
by the lever pedal, finish the grooving of the eye at a single blow, by
striking against each other, with the head of the needle between them.

The whole of the needles thus prepared are thrown pell-mell into a sort
of drawer or box, in which they are by a few dexterous jerks of the
workman’s hand made to arrange themselves parallel to each other.

The needles are now ready for the tempering; for which purpose they are
weighed out in quantities of about 30 pounds, which contain from 250,000
to 500,000 needles, and are carried in boxes to the _temperer_. He
arranges these upon sheet-iron plates, about 10 inches long, and 5
inches broad, having borders only upon the two longer sides. These
plates are heated in a proper furnace to bright redness for the larger
needles, and to a less intense degree for the smaller; they are taken
out, and inverted smartly over a cistern of water, so that all the
needles may be immersed at the same moment, yet distinct from one
another. The water being run off from the cistern, the needles are
removed, and arranged by agitation in a box, as above described. Instead
of heating the needles in a furnace, some manufacturers heat them by
means of a bath of melted lead in a state of ignition.

After being suddenly plunged in the cold water, they are very hard and
excessively brittle. The following mode of tempering them is practised
at Neustadt. The needles are thrown into a sort of frying-pan along with
a quantity of grease. The pan being placed on the fire, the fatty matter
soon inflames, and is allowed to burn out; the needles are now found to
be sufficiently well tempered. They must, however, be re-adjusted upon
the steel anvil, because many of them get twisted in the hardening and
tempering.

[Illustration: 762 763]

_Polishing_ is the longest, and not the least expensive process in the
needle manufacture. This is done upon bundles containing 500,000
needles; and the same machine under the guidance of one man, polishes
from 20 to 30 bundles at a time; either by water or steam power. The
needles are rolled up in canvas along with some quartzose sand
interstratified between their layers, and the mixture is besmeared with
rape-seed oil. _Fig._ 762. represents one of the rolls or packets of
needles 12 inches long, strongly bound with cords. These packets are
exposed to the to-and-fro pressure of wooden tables, by which they are
rolled about, with the effect of causing every needle in the bundle to
rub against its fellow, and against the siliceous matter, or emery,
enclosed in the bag. _Fig._ 763. represents an improved table for
polishing the needles by attrition-bags. The lower table M M is movable,
whereas in the old constructions it was fixed; the table C has merely a
vertical motion, of pressure upon the bundles, whereas formerly it had
both a vertical and horizontal motion. Several bundles may obviously be
polished at once in the present machine. The table M M may be of any
length that is required, and from 24 to 27 inches broad; resting upon
the wooden rollers B, B, B, placed at suitable distances, it receives a
horizontal motion, either by hand or other convenient power; the packets
of needles A, A, A, are laid upon it, and over them the tables C, C, C,
which are lifted by means of the chains K, K, K, and the levers L, L, L,
in order to allow the needles to be introduced or removed. The see-saw
motion forces the _rouleaux_ to turn upon their own axes, and thereby
creates such attrition among their contents as to polish them. The
workman has merely to distribute these rolls upon the table M, in a
direction perpendicular to that in which the table moves; and whenever
one of them gets displaced, he sets it right, lifting by the help of the
chain the loaded table. The table makes about 20 horizontal double
vibrations in the minute; whereby each bundle, running over 24 inches
each time, passes through 40 feet per minute, or 800 yards in the hour.

[Illustration: 764]

_Scouring by the cask._ After being worked during 18 or 20 hours under
the tables, the needles are taken out of the packets, and put into
wooden bowls, where they are mixed with sawdust to absorb the black
grease upon their surfaces. They are next introduced into a cask, _fig._
764., and a workman seizing the winch P, turns it round a little; he now
puts in some more sawdust at the door, A, B, which is then shut by the
clasps G G, and continues the rotation till the needles be quite clean
and clear in their eyes; which he ascertains by taking out a sample of
them from time to time.

_Winnowing_ is the next process, by means of a mechanical ventilator
similar to that by which corn is winnowed. The sawdust is blown away,
and the grinding powder is separated from the needles, which remain
apart clean and bright.

The needles are in the next place arranged in order, by being shaken, as
above described, in a small somewhat concave iron tray. After being thus
laid parallel to each other, they are shaken up against the end of the
tray, and accumulated in a nearly upright position, so that they can be
seized in a heap and removed in a body upon a pallet knife, with the
help of the forefinger.

[Illustration: 765 766]

The preceding five operations, of making up the _rouleaux_, rolling them
under the tables, scouring the needles in the cask, winnowing, and
arranging them, are repeated ten times in succession, in manufacturing
the best articles; the only variation being in the first process.
Originally the bundles of needles are formed with alternate layers of
siliceous schistus and needles; but after the seventh time, bran freed
from flour by sifting is substituted for the schistus. The subsequent
four processes are, however, repeated as described. It has been found in
England, that emery powder mixed with quartz and mica or pounded
granite, is preferable to every thing else for polishing needles at
first by attrition in the bags; at the second and following operations,
emery mixed with olive oil is used, up to the eighth and ninth, for
which putty or oxide of tin with oil is substituted for the emery; at
the tenth the putty is used with very little oil; and lastly bran is
employed to give a finish. In this mode of operating, the needles are
_scoured_ in the copper cask shown in elevation _fig._ 765., and in
section _fig._ 766. The inner surface of this cask is studded with
points to increase the friction among the needles; and a quantity of hot
soap suds is repeatedly introduced to wash them clean. The cask must be
slowly turned upon its axis, for fear of injuring the mass of needles
which it contains. They are finally dried in the wooden cask by
attrition with sawdust; then wiped individually with a linen rag or soft
leather; when the damaged ones are thrown aside.

[Illustration: 767 768]

_Sorting of the needles._ This operation is performed in a dry upper
chamber, kept free from damp by proper stoves. Here all the points are
first laid the same way; and the needles are then picked out from each
other in the order of their polish. The sorting is effected with
surprising facility. The workman places 2000 or 3000 needles in an iron
ring, _fig._ 767., two inches in diameter, and sets all their heads in
one plane; then on looking carefully at their points, he easily
recognises the broken ones; and by means of a small hook fixed in a
wooden handle, _fig._ 768., he lays hold of the broken needle, and turns
it out. These defective needles pass into the hands of another workman,
who points them anew upon a grindstone, and they form articles of
inferior value. The needles which have got bent in the polishing must
now be straightened. The whole are finally arranged exactly according to
their lengths by the tact of the finger and thumb of the sorter.

The needles are divided into quantities for packing in blue papers, by
putting into a small balance the equivalent weight of 100 needles, and
so measuring them out without the trouble of counting them individually.

[Illustration: 769]

The _bluer_ receives these packets, and taking 25 of their needles at a
time between the forefinger and thumb, he presses their points against a
very small hone-stone of compact micaceous schist, mounted in a little
lathe, as shown in _fig._ 769., he turns them briskly round, giving the
points a bluish cast, while he polishes and improves them. This partial
polish is in the direction of the axis; that of the rest of the needle
is transverse, which distinguishes the boundaries of the two. The little
hone-stone is not cylindrical, but quadrangular, so that it strikes
successive blows with its corners upon the needles as it revolves,
producing the effect of filing lengthwise. Whenever these angles seem to
be blunted, they are set again by the _bluer_.

It is easy to distinguish good English needles from spurious imitations;
because the former have their axis coincident with their points, which
is readily observed by turning them round between the finger and thumb.

The construction of a needle requires, as already stated, about 120
operations; but they are rapidly and uninterruptedly successive. A child
can _trim_ the eyes of 4000 needles per hour.

When we survey a manufacture of this kind, we cannot fail to observe,
that the diversity of operations which the needles undergo bears the
impress of great mechanical refinement. In the arts, to divide labour,
is to abridge it; to multiply operations, is to simplify them; and to
attach an operative exclusively to one process, is to render him much
more economical and productive.


NEROLI, is the name given by perfumers to the essential oil of orange
flowers. It is procured by distillation with water, in the same way as
the other volatile oils. Since in distilling water from neroli, an aroma
is obtained different from that of the orange-flower, it has been
concluded that the distilled water of orange-flowers owes its scent to
some principle different from an essential oil.


NET (_Filet_, _reseau_, Fr.; _Netz_, Germ.); is a textile fabric of
knotted meshes, for catching fish, and other purposes. Each mesh should
be so secured as to be incapable of enlargement or diminution. The
French government offered in 1802 a prize of 10,000 francs to the person
who should invent a machine for making nets upon automatic principles,
and adjudged it to M. Buron, who presented his mechanical invention to
the _Conservatoire des Arts et Métiers_. It does not appear, however,
that this machine has accomplished the object in view; for no
establishment was ever mounted to carry it into execution. Nets are
usually made by the fishermen and their families during periods of
leisure. The formation of a mesh is too simple a matter to require
description in this Dictionary.


NEUTRALIZATION, is the state produced when acid and alkaline matters are
combined in such proportions that neither predominates, as evinced by
the colour of tincture of litmus and cabbage remaining unaffected by the
combination.


NICARAGUA WOOD, is the wood of the _Cæsalpinia echinata_, a tree which
grows in Nicaraca. It is used with solution of tin as a mordant to dye a
bright but fugitive red. It is an inferior sort of Brazil wood.


NICKEL, is a metal rather sparingly found, and in few localities; being
usually associated with cobalt. Native nickel occurs at Westerwald in
the Erzgebirge, in Bohemia, combined with arsenic, under the significant
name of _Kupfernickel_; with cobalt, iron, and copper, as
_Arsenic-nickel_, in the Harz; at Riechelsdorf in Hessia; as an oxide,
in _Nickelschwärtze_; as a sulphuret of nickel in _Haarkies_; as a
sulphuret and arseniate of nickel in _Nickelglanz_; and with sulphur and
antimony in _Nickelspiess glanzerz_ at Siegen. Nickel is always present
in meteoric stones. Kupfernickel occurs in numerous external shapes; as
reniform, globular, botroidal, arborescent, massive, and disseminated;
fracture, coarse or fine grained, with metallic lustre; colour, copper
red, occasionally brown and gray; in silver and cobalt veins, in gneiss,
sienite, mica-slate, kupfer-schiefer, accompanied by speisse cobalt,
native silver, quartz, &c. It is found in Westphalia near Olpe, in
Hessia at Riechelsdorf, and Biber, in Baden; in the Saxon Erzgebirge
near Schneeberg, and Freiberg; in Bohemia, at Joachimsthal; in
Thuringia, at Saalfeld; in Steyermark near Schladming; in Hungary,
France, and England.

Since the manufacture of German silver, or _Argentane_, became an object
of commercial importance, the extraction of nickel has been undertaken
upon a considerable scale. The cobalt ores are its most fruitful
sources, and they are now treated by the method of Wöhler, to effect the
separation of the two metals. The arsenic is expelled by roasting the
powdered _speise_ first by itself, next with the addition of charcoal
powder, till the garlic smell be no longer perceived. The residuum is to
be mixed with three parts of sulphur and one of potash, melted in a
crucible with a gentle heat, and the product being edulcorated with
water, leaves a powder of metallic lustre, which is a sulphuret of
nickel free from arsenic; while the arsenic associated with the sulphur,
and combined with the resulting sulphuret of potassium, remains
dissolved. Should any arsenic still be found in the sulphuret, as may
happen if the first roasting heat was too great, the above process must
be repeated. The sulphuret must be finally washed, dissolved in
concentrated sulphuric acid, with the addition of a little nitric, the
metal must be precipitated by a carbonated alkali, and the carbonate
reduced with charcoal.

In operating upon kupfernickel, or speise, in which nickel predominates,
after the arsenic, iron, and copper have been separated, ammonia is to
be digested upon the mixed oxides of cobalt and nickel, which will
dissolve them into a blue liquor. This being diluted with distilled
water deprived of its air by boiling, is to be decomposed by caustic
potash, till the blue colour disappears, when the whole is to be put
into a bottle tightly stoppered, and set aside to settle. The green
precipitate of oxide of nickel, which slowly forms, being freed by
decantation from the supernatant red solution of oxide of cobalt, is to
be edulcorated and reduced to the metallic state in a crucible
containing crown glass. Pure nickel in the form of a metallic powder is
readily obtained by exposing its oxalate to moderate ignition.

The reduction of the oxide of nickel with charcoal requires the heat of
a powerful air furnace or smith’s forge.

Nickel possesses a fine silver white colour and lustre; it is hard, but
malleable, both hot and cold; may be drawn into wire 1/50 of an inch,
and rolled into plates 1/500 of an inch thick. A small quantity of
arsenic destroys its ductility. When fused it has a specific gravity of
8·279, and when hammered, of 8·66 or 8·82; it is susceptible of
magnetism, in a somewhat inferior degree to iron, but superior to
cobalt. Mariner’s compasses may be made of it. Its melting point is
nearly as high as that of manganese. It is not oxidized by contact of
air, but may be burned in oxygen gas.

There is one oxide and two suroxides of nickel. The oxide is of an
ash-gray colour, and is obtained by precipitation with an alkali from
the solution of the muriate or nitrate. The niccolous suroxide of
Berzelius is black, and may be procured by exposing the nitrate to a
heat under redness. The niccolic suroxide has a dirty pale green colour;
but its identity is doubtful.


NICOTIANINE, is the name of an oil recently extracted from the leaves of
tobacco, which possesses the smell of tobacco smoke.


NICOTINE, is a peculiar principle, obtainable from the leaves and seeds
of tobacco (_nicotiana tabacum_), by infusing them in acidulous water,
evaporating the infusion to a certain point, adding lime to it,
distilling and treating the product which comes over with ether. It is
colourless, has an acrimonious taste, a pungent smell, remains liquid at
20° F., mixes in all proportions with water, but is in a great measure
separable from it by ether, which dissolves it abundantly. It combines
with acids, and forms salts acrid and pungent like itself; the
phosphate, oxalate, and tartrate being crystallizable. Nicotine causes
the pupils to contract. A single drop of it is sufficient to kill a dog.


NITRATE OF AMMONIA, is prepared by neutralizing nitric acid with
carbonate of ammonia, and crystallizing the solution.


NITRATE OF LEAD (_Nitrate de plomb_, Fr.; _Salpetersaures bleioxyd_,
Germ.); is made by saturating somewhat dilute nitric acid with oxide of
lead (litharge), evaporating the neutral solution till a pellicle
appears, and then exposing it in a hot chamber till it be converted into
crystals, which are sometimes transparent, but generally opaque white
octahedrons. Their spec. grav. is 4·068; they have a cooling, sweetish,
pungent taste. They dissolve in 7 parts of cold, and in much less
boiling water; they fuse at a moderate elevation of temperature, emit
oxygen gas, and pass into oxide of lead. Their constituents are 67·3
oxide, and 32·7 acid. Nitrate of lead is much employed in the chrome
yellow style of CALICO-PRINTING; which see.

There are three other compounds of nitric acid and lead oxide; viz. the
bi-basic, the tri-basic, and the se-basic; which contain respectively 2,
3, and 6 atoms of base to 1 of acid.


NITRATE OF POTASH, _Nitre_, _Saltpetre_. (_Nitrate de potasse_, Fr.;
_Salpetersaures kali_, Germ.) This salt occurs native as an
efflorescence upon limestones, sandstones, marls, chalk, and calctuff;
it forms a saline crust in caverns, as also upon the surface of the
ground in certain places, especially where animal matters have been
decomposed. Such caverns exist in Germany near Homburg (Burkardush); in
Apulia upon the Adriatic sea (Pulo di Mofetta); in France; in the East
Indies; in Ceylon, where 22 nitriferous caverns are mentioned; in North
America, at Crooked river, Tennessee, Kentucky, and upon the Missouri;
in Brazil, Teneriffe, and Africa. Nitre occurs as an efflorescence upon
the ground in Arragon, Hungary, Podolia, Sicily, Egypt, Persia, Bengal,
China, Arabia, North America, and South America. Several plants contain
saltpetre; particularly borage, dill, tobacco, sunflowers, stalks of
maize, beet-root, bugloss, parietaria, &c. It has not hitherto been
found in animal substances.

The question has been frequently put; how is nitre annually reproduced
upon the surface of limestones, and the ground, after it has been
removed by washing? It has been said, in reply, that as secondary
limestones contain remains of animal matters, the oxygen of the
atmosphere, absorbed in virtue of the porous structure, will combine
with their azote to form nitric acid; whence nitrate of lime will
result. Where potash is present in the ground, a nitrate of that base
will be next formed. The generation of nitre is in all cases limited to
a very small distance from the surface of porous stones; no further,
indeed, than where atmospherical air and moisture can penetrate; and
none is ever produced upon the surface of compact stones, such as marble
and quartz, or of argillaceous minerals. Dr. John Davy and M. Longchamp
have advanced an opinion, that the presence of azotized matter is not
necessary for the generation of nitric acid or nitrous salts, but that
the oxygen and azote of the atmosphere, when condensed by capillarity,
will combine in such proportions as to form nitric acid, through the
agency of moisture and of neutralizing bases, such as lime, magnesia,
potash, or soda. They conceive that as spongy platina serves to combine
oxygen and hydrogen into water, or the vapour of alcohol and oxygen into
acetic acid, and as the peroxide as well as the hydrate of iron, and
argillaceous minerals, serve to generate ammonia from the oxygen of the
air and the hydrogen of water; in like manner, porous limestones,
through the agency of water, operate upon the constituents of the
atmosphere to produce nitric acid, without the presence of animal
matter. This opinion may certainly be maintained: for in India, Spain,
and several other countries, at a distance from all habitations, immense
quantities of saltpetre are reproduced in soils which have been washed
the year before. But, on the other hand, it is known that the production
of this salt may be greatly facilitated and increased by the admixture
of animal offals with calcareous earths.

The spontaneous generation of nitre in Spain, Egypt, and especially in
India, is sufficient to supply the wants of the whole world. There this
salt is observed to form upon the surface of the ground in silky tufts,
or even in slender prismatic crystals, particularly during the
continuance of the hot weather that succeeds copious rains. These saline
efflorescences, after being collected by rude besoms of broom, are
lixiviated, allowed to settle, evaporated, and crystallized. In France,
Germany, Sweden, Hungary, &c., vast quantities of nitrous salts are
obtained by artificial arrangements called _nitriaries_, or nitre-beds.
Very little nitrate of potash, indeed, is obtained in the first place;
but the nitrates of lime and magnesia, which being deliquescent, remain
in the nitrous earths in a semi-liquid state. The operation of
converting these salts into good nitre is often sufficiently complex, in
consequence of the presence of several muriates, which are difficult to
eliminate.

The following instructions have been given by the consulting committee
of _poudres et salpêtres_ in France, for the construction of their
_nitrières artificielles_. The permeability of the materials to the
atmospherical air, being found to be as indispensable as is the presence
of a base to fix the nitric acid at the instant of its formation, the
first measure is to select a light friable earth, containing as much
carbonate of lime or old mortar-rubbish as possible; and to
interstratify it with beds of dung, five or six inches thick, till a
considerable heap be raised in the shape of a truncated pyramid, which
should be placed under an open shed, and kept moist by watering it from
time to time. When the whole appears to be decomposed into a kind of
mould, it is to be spread under sheds in layers of from two to three
feet thick; which are to be watered occasionally with urine and the
drainings of dunghills, taking care not to soak them too much, lest they
should be rendered impermeable to the air, though they should be always
damp enough to favour the absorption and mutual action of the
atmospherical gases. Moist garden mould affords an example of the
physical condition most favourable to nitre-beds. The compost should be
turned over, and well mixed with the spade once at least in every
fortnight, and the sides of the shed should be partially closed, for
although air be essential, wind is injurious, by carrying off the acid
vapours, instead of allowing them to rest incumbent upon, and combine
with, the bases. The chemical reaction is slow and successive, and can
be made effective only by keeping the agents and materials in a state of
quiescence. The whole process lasts two years; but since organic matters
would yield in the lixiviation several soluble substances detrimental to
the extraction of saltpetre, they must not be added during the
operations of the latter six months; nor must any thing except clear
water be used for watering during this period; at the end of which the
whole organic ingredients of the beds will be totally decomposed. Where
dung is not sufficiently abundant for the above stratifications, a
nitre-bed should be formed in a stable with friable earth, covered with
a layer of litter; after four months the litter is to be lifted off, the
earth is to be turned over, then another layer of fresh earth, 8 or 9
inches thick, is to be placed over it, and a layer of the old and fresh
litter over all. At the end of other four months, this operation is to
be repeated; and in the course of a year the whole is ready to be
transferred into the regular nitre-beds under a shed, as above
described. Such are the laborious and disagreeable processes practised
by the peasants of Sweden, each of whom is bound by law to have a
nitre-bed, and to furnish a certain quantity of nitre to the state every
year. His _nitriary_ commonly consists of a small hut built of boards,
with a bottom of rammed clay, covered by a wooden floor, upon which is
spread a mixture of ordinary earth with calcareous sand or marl, and
lixiviated wood-ashes. This mixture is watered with stable urine, and
its surface is turned over once a week in summer, and once a fortnight
in winter. In some countries, walls 2 or 3 feet thick, and 6 or 7 high,
are raised with the nitrifying compost, interspersed with weeds and
branches of trees, in order at once to bind them together, and to favour
the circulation of air. These walls are thatched with straw; they are
placed with one of their faces in the direction of the rains; and must
be moistened with water not rich in animal matter. One side of the walls
is upright and smooth; while the other is sloped or terraced, to favour
the admission of humidity into their interior. The nitre eventually
forms a copious efflorescence upon the smooth side, whence it may be
easily scraped off.

M. Longchamp, convinced that organic matters are a useless expense, and
not in the least essential to nitrification, proposes to establish
nitre-beds where fuel and labour are cheapest, as amidst forests,
choosing as dry and low a piece of ground as possible, laying them out
upon a square space of about 1000 feet in each side, in the middle of
which the graduation-house may be built, and alongside of it sheds for
the evaporation furnaces and pans. Upon each of the four sides the
_nitrifying_ sheds are to be erected, 130 feet long by 30 feet wide,
where the lixiviation would be carried on, and whence the water would be
conducted in gutters to the graduation-house. The sheds are to be closed
at the sides by walls of _pisé_, and covered with thatch. No substance
is so favourable to nitrification as the natural stony concretion known
under the name of lime-tuf. In Touraine, where it is used as a building
stone, the saltpetre makers re-establish the foundations of old houses
at their own expense, provided they are allowed to carry off the old
tuf, which owes its nitrifying properties not only to its chemical
nature, but to its texture, which being of a homogeneous porosity,
permits elastic fluids and vapours to pass through it freely in all
directions. With the rough blocks of such tuf, walls about 20 inches
thick, and moderately high, are to be raised, upon the principles above
prescribed; in the absence of tuf, porous walls may be raised with a
mixture of arable soil, sand, and mortar-rubbish, chalk or rich marl.
The walls ought to be kept moist.

In France, the greater part of the indigenous saltpetre is obtained by
lixiviating the mortar-rubbish of old buildings, especially of those
upon the ground-floor, and in sunk cellars; which are by law reserved
for this purpose. The first object of the manufacturer is then to
ascertain the richness of his materials in nitrous salts, to see if they
be worth the trouble of working; and this point he commonly determines
merely by their saline, bitter, and pungent taste, though he might
readily have recourse to the far surer criteria of lixiviation and
evaporation. He next pounds them coarsely, and puts them into large
casks open at top, and covered with straw at bottom; which are placed in
three successive levels. Water is poured into the casks till they are
full, and after 12 hours’ digestion it is run off, loaded with the
salts, by a spigot near the bottom. A fresh quantity of water is then
added, and drawn off after an interval of four hours; even a third and
fourth lixiviation are had recourse to; but these weak liquors are
reserved for lixiviating fresh rubbish. The contents of the casks upon
the second and third lower levels are lixiviated with the liquors of the
upper cask, till the lyes indicate from 12 to 14 degrees of Baumé’s
hydrometer. They are now fit for evaporating to a greater density, and
of then receiving the dose of wood-ashes requisite to convert the
materials of lime and magnesia into nitrate of potash, with the
precipitation of the carbonates of magnesia and lime. The solution of
nitre is evaporated in a copper pan, and as it boils, the scum which
rises to the surface must be diligently skimmed off into a cistern
alongside. Muriate of soda being hardly more soluble in boiling than in
cold water, separates during the concentration of the nitre, and is
progressively removed with cullender-shaped ladles. The fire is
withdrawn whenever the liquor has acquired the density of 80° B.; it is
allowed to settle for a little while, and is then drawn off, by a lead
syphon adjusted some way above the bottom, into iron vessels, to cool
and crystallize. The crystals thus obtained are set to drain, then
re-dissolved and re-crystallized. The further purification of nitre, is
fully described under the article GUNPOWDER.

The annual production of saltpetre in France, by the above-described
processes, during the wars of the Revolution, amounted to 2000 tons (2
millions of kilogrammes) of an article fit for the manufacture of
gunpowder; of which seven-twentieths were furnished by the saltpetre
works of Paris alone. Considerably upwards of six times that quantity of
common and cubic nitre were imported into the United Kingdom, for home
consumption, during the year ending January 5, 1838.

Nitrate of potash crystallizes in six-sided prisms, with four narrow and
two broad faces: the last being terminated by a dihedral summit, or
two-sided acumination; they are striated lengthwise, and have fissures
in their long axis, which are apt to contain mother water. The spec.
gravity of nitre, varies from 1·93 to 2·00. It possesses a cooling,
bitterish-pungent taste, is void of smell, permanent in the air when
pure, fuses at a heat of about 662, into an oily-looking liquid, and
concretes upon cooling into a solid mass, with a coarsely radiating
fracture. This has got the unmeaning names of sal-prunelle and mineral
crystal. At a red heat, nitre gives out at first a great deal of pretty
pure oxygen gas; but afterwards nitrous acid fumes, while potash remains
in the retort. It is soluble in 7 parts of water at 32°; in about 3-1/2
at 60° F., in less than half a part at 194°, and in four-tenths at 212°.
It is very slightly soluble in spirit of wine, and not at all in
absolute alcohol. It causes a powerful deflagration when thrown upon
burning coals; and when a mixture of it with sulphur is thrown into a
red-hot crucible, a very vivid light is emitted. Its constituents are,
46·55 potash, and 53·45 nitric acid.

Nitre is applied to many purposes:--1, to the manufacture of gunpowder;
2, to that of sulphuric acid; 3, to that of nitric acid, though nitrate
of soda or cubic nitre has lately superseded this use of it to a
considerable extent; 4, to that of flint-glass; 5, it is used in
medicine; 6, for many chemical and pharmaceutical preparations; 7, for
procuring by deflagration with charcoal or cream of tartar, pure
carbonate of potash, as also black and white fluxes; 8, for mixing with
salt in curing butcher meat; 9, in some countries for sprinkling in
solution upon grain, to preserve it from insects; 10, for making
fire-works. See FIRE-WORKS.

An Account of the quantities of Saltpetre and Cubic Nitre imported into,
exported from, and retained for consumption in the United Kingdom. Duty
6_d._ per cwt:--

                 Imported in
           1835.    1836.    1837.
  cwts.  264,338; 279,902; 349,993.

                 Exported in
           1835.   1836.   1837.
  cwts.   73,379; 38,414; 93,024.

        Retained for Consumption in
           1835.    1836.    1837.
  cwts.  204,580; 242,131; 256,969.

Duty received in 1837, _£_6,424.


NITRATE OF SILVER (_Nitrate d’argent_, Fr.; _Silbersalpeter_, Germ.); is
prepared by saturating pure nitric acid of specific grav. 1·25 with pure
silver, evaporating the solution, and crystallizing the nitrate. When
the drained crystals are fused in a platina capsule, and cast into
slender cylinders in silver moulds, they constitute the lunar caustic of
the surgeon. This should be white, and unchangeable by light. It is
deliquescent in moist air. The crystals are colourless transparent 4 and
6 sided tables; they possess a bitter, acrid, and most disagreeable
metallic taste; they dissolve in their own weight of cold, and in much
less of hot water; are soluble in four parts of boiling alcohol, but not
in nitric acid; they deflagrate on redhot coals, like all the nitrates;
and detonate with phosphorus when the two are struck together upon an
anvil. They consist of 68·2 of oxide, and 31·8 of acid. Nitrate of
silver, when swallowed, is a very energetic poison: but it may be
readily counteracted, by the administration of a dose of sea-salt, which
converts the corrosive nitrate into the inert chloride of silver. Animal
matter, immersed in a weak solution of neutral nitrate of silver, will
keep unchanged for any length of time; and so will polished iron or
steel. Nitrate of silver is such a delicate reagent of hydrochloric or
muriatic acid, as to show by a sensible cloud, the presence of one 113
millionth part of it, or one 7 millionth part of sea-salt in distilled
water. It is much used under the name of indelible ink, for writing upon
linen with a pen; for which purpose one drachm of the fused salt should
be dissolved in three quarters of an ounce of water, adding to the
solution as much water of ammonia as will re-dissolve the precipitated
oxide, with sap-green to colour it, and gum-water to make the volume
amount to one ounce. Traces written with this liquid should be first
heated before a fire to expel the excess of ammonia, and then exposed to
the sun-beam to blacken. Another mode of using nitrate of silver as an
indelible ink, is to imbue the linen first with solution of carbonate of
soda, to dry the spot, and write upon it with a solution of nitrate of
silver, thickened with gum, and tinted with sap-green.


NITRATE OF SODA, _Cubical Nitre_ (_Nitrate de soude_, Fr.;
_Würfelsalpeter_, Germ.); occurs under the nitre upon the lands in
Spain, India, Chile, and remarkably in Peru, in the districts of Atacama
and Taracapa, where it forms a bed several feet thick. It appears in
several places upon the surface, and extends over a space of more than
40 leagues, approaching near to the frontiers of Chile. It is sometimes
efflorescent, sometimes crystallized, but oftener confusedly mixed with
clay and sand. This immensely valuable deposit is only three days’
journey from the port of Conception in Chile, and from Iquiqui, another
harbour situated in the southern part of Peru.

Nitrate of soda may be artificially prepared by neutralizing nitric acid
with soda, and crystallizing the solution. It crystallizes in rhomboids,
has a cooling, pungent, bitterish taste, less disagreeable than nitre;
it becomes moist in the air; dissolves in 3 parts of water at 60° F., in
less than 1 part of boiling water; deflagrates more slowly than nitre,
and with an orange yellow flame. It consists, in its dry state, of 36·6
soda and 63·4 nitric acid; but its crystals contain one prime
equivalent of water; hence they are composed of, acid 56·84, base 33·68,
water 9·47.

It is susceptible of the same applications as nitre, with the exception
of making gunpowder; for which it is not adapted, on account of its
deliquescent property.


NITRATE OF STRONTIA. (_Nitrate de strontiane_, Fr.; _Salpetersaurer
strontian_, Germ.) This salt is usually prepared from the sulphuret of
strontium, obtained by decomposing sulphate of strontia with charcoal,
by strong ignition of the mixed powders in a crucible. This sulphuret
being treated with water, and the solution being filtered, is to be
neutralized with nitric acid, as indicated by the test of turmeric
paper; care being taken to avoid breathing the noxious sulphuretted
hydrogen gas, which is copiously disengaged. The neutral nitrate being
properly evaporated and set aside, affords colourless, transparent,
slender octahedral crystals. It has a cooling, yet somewhat acrid taste;
is soluble in 5 parts of cold, and in one half part of boiling water, as
also in alcohol; is permanent in the air, deflagrates upon burning
coals, gives off oxygen when calcined, and leaves caustic strontia. The
salt consists of 48·9 strontia and 51·1 nitric acid. That salt is
anhydrous; but there is another variety of it, which contains nearly 40
per cent. of water of crystallization, which occurs in large
octahedrons. This is preferred for fire-works, because by efflorescence
it is easily obtained in a fine powder, which mixes more intimately with
the chlorate of potash and charcoal, for the composition of the
brilliant red fires, now so much admired in theatrical conflagrations.


NITRIC ACID, _Aquafortis_ (_Acide nitrique_, Fr.; _Salpetersaüre_,
Germ.); exists, in combination with the bases, potash, soda, lime,
magnesia, in both the mineral and vegetable kingdoms. This acid is never
found insulated. It was distilled from saltpetre so long ago as the 13th
century, by igniting that salt, mixed with copperas or clay, in a
retort. Nitric acid is generated when a mixture of oxygen and nitrogen
gases, confined over water or an alkaline solution, has a series of
electrical explosions passed through it. In this way the salubrious
atmosphere may be converted into corrosive aquafortis. When a little
hydrogen is introduced into the mixed gases, standing over water, the
chemical agency of the electricity becomes more intense, and the acid is
more rapidly formed from its elements, with the production of some
nitrate of ammonia.

Nitric acid is usually made on the small scale by distilling, with the
heat of a sand-bath, a mixture of 3 parts of pure nitre, and 2 parts of
strong sulphuric acid, in a large glass retort, connected by a long
glass tube with a globular receiver surrounded by cold water. By a well
regulated distillation, a pure acid, of specific gravity 1·500, may be
thus obtained, amounting in weight to about two-thirds of the nitre
employed. To obtain easily the whole nitric acid, equal weights of nitre
and concentrated sulphuric acid may be taken; in which case but a
moderate heat need be applied to the retort. The residuum will be
bisulphate of potash. When only the single equivalent proportion of
sulphuric acid is used, namely 48 parts for 100 of nitre, a much higher
heat is required to complete the distillation, whereby more or less of
the nitric acid is decomposed, while a compact neutral sulphate of
potash is left in the retort, very difficult to remove by solution in
water, and therefore apt to destroy the vessel.

Aquafortis is manufactured upon the great scale in iron pots or
cylinders of the same construction as I have described under muriatic
acid. The more concentrated the sulphuric acid is, the less corrosively
will it act upon the metal; and it is commonly used in the proportion of
one part by weight to two of nitre. The salt being introduced into the
cool retort, and the lid being luted tight, the acid is to be slowly
poured in through the aperture _f_, _fig._ 748.; while the aperture _g_
is connected by a long glass tube with a range of balloons inserted into
each other, and laid upon a sloping bed of sand. The bottle _i_, with 3
tubulures partly filled with water, which is required for condensing
muriatic acid gas, must, for the present purpose, be replaced by a
series of empty receivers, either of glass or salt-glazed stoneware. The
cylinders should be only half filled, and be worked off by a gradually
raised heat.

Commercial aquafortis is very generally contaminated with sulphuric and
muriatic acids, as also with alkaline sulphates and muriates. The
quantity of these salts may be readily ascertained by evaporating in a
glass capsule a given weight of the aquafortis; while that of the
muriatic acid may be determined by nitrate of silver; and of sulphuric
acid, by nitrate of baryta. Aquafortis may be purified in a great
measure, by re-distillation at a gentle heat; rejecting the first liquid
which comes over, as it contains the chlorine impregnation; receiving
the middle portion as genuine nitric acid; and leaving a residuum in the
retort, as being contaminated with sulphuric acid.

Since nitrate of soda has been so abundantly imported into Europe from
Peru, it has been employed by many manufacturers in preference to nitre
for the extraction of nitric acid, because it is cheaper, and because
the residuum of the distillation, being sulphate of soda, is more
readily removed by solution from glass retorts, when a range of these
set in a gallery furnace is the apparatus employed. Nitric acid of
specific gravity 1·47 may be obtained colourless; but by further
concentration a portion of it is decomposed, whereby some nitrous acid
is produced, which gives it a straw-yellow tinge. At this strength it
exhales white or orange fumes, which have a peculiar, though not very
disagreeable smell; and even when largely diluted with water, it tastes
extremely sour. The greatest density at which it can be obtained is 1·51
or perhaps 1·52, at 60° F., in which state, or even when much weaker, it
powerfully corrodes all animal, vegetable, and most metallic bodies.
When slightly diluted it is applied, with many precautions, to silk and
woollen stuffs, to stain them of a bright yellow hue. See
CALICO-PRINTING; page 240.

In the dry state, as it exists in nitre, this acid consists of 26·15
parts by weight of azote, and 73·85 of oxygen; or of 2 volumes of the
first gas, and 5 volumes of the second.

When of specific gravity 1·5, it boils at about 210° Fahr.; of 1·45, it
boils at about 240°; of 1·42, it boils at 253°; and of 1·40, at 246° F.
If an acid stronger than 1·420 be distilled in a retort, it gradually
becomes weaker; and if weaker than 1·42, it gradually becomes stronger,
till it assumes that standard density. Acid of specific gravity 1·485
has no more action upon tin than water has, though when either stronger
or weaker it oxidizes it rapidly, and evolves fumes of nitrous gas with
explosive violence. In my two papers upon nitric acid published in the
fourth and sixth volumes of the Journal of Science (1818 and 1819), I
investigated the chemical relations of these phenomena. Acid of 1·420
consists of 1 atom of dry acid, and 4 of water; acid of 1·485, of 1 atom
of dry acid, and 2 of water; the latter compound possesses a stable
equilibrium as to chemical agency; the former as to calorific. Acid of
specific gravity 1·334, consisting of 7 atoms of water, and 1 of dry
acid, resists the decomposing agency of light. Nitric acid acts with
great energy upon most combustible substances, simple or compound,
giving up oxygen to them, and resolving itself into nitrous gas, or even
azote. Such is the result of its action upon hydrogen, phosphorus,
sulphur, charcoal, sugar, gum, starch, silver, mercury, copper, iron,
tin, and most other metals.

A Table of Nitric Acid, by Dr. Ure.

  +--------+-------+--------+
  |Specific| Liq.  |Dry acid|
  |gravity.| Acid  |in 100. |
  |        |in 100.|        |
  +--------+-------+--------+
  | 1·5000 |  100  | 79·700 |
  | 1·4980 |   99  | 78·903 |
  | 1·4960 |   98  | 78·106 |
  | 1·4940 |   97  | 77·309 |
  | 1·4910 |   96  | 76·512 |
  | 1·4880 |   95  | 75·715 |
  | 1·4850 |   94  | 74·918 |
  | 1·4820 |   93  | 74·121 |
  | 1·4790 |   92  | 73·324 |
  | 1·4760 |   91  | 72·527 |
  | 1·4730 |   90  | 71·730 |
  | 1·4700 |   89  | 70·933 |
  | 1·4670 |   88  | 70·136 |
  | 1·4640 |   87  | 69·339 |
  | 1·4600 |   86  | 68·542 |
  | 1·4570 |   85  | 67·745 |
  | 1·4530 |   84  | 66·948 |
  | 1·4500 |   83  | 66·155 |
  | 1·4460 |   82  | 65·354 |
  | 1·4424 |   81  | 64·557 |
  | 1·4385 |   80  | 63·760 |
  | 1·4346 |   79  | 62·963 |
  | 1·4306 |   78  | 62·166 |
  | 1·4269 |   77  | 61·369 |
  | 1·4228 |   76  | 60·572 |
  | 1·4189 |   75  | 59·775 |
  | 1·4147 |   74  | 58·978 |
  | 1·4107 |   73  | 58·181 |
  | 1·4065 |   72  | 57·384 |
  | 1·4023 |   71  | 56·587 |
  | 1·3978 |   70  | 55·790 |
  | 1·3945 |   69  | 54·993 |
  | 1·3882 |   68  | 54·196 |
  | 1·3833 |   67  | 53·399 |
  | 1·3783 |   66  | 52·602 |
  | 1·3732 |   65  | 51·805 |
  | 1·3681 |   64  | 51·068 |
  | 1·3630 |   63  | 50·211 |
  | 1·3579 |   62  | 49·414 |
  | 1·3529 |   61  | 48·617 |
  | 1·3477 |   60  | 47·820 |
  | 1·3427 |   59  | 47·023 |
  | 1·3376 |   58  | 46·226 |
  | 1·3323 |   57  | 45·429 |
  | 1·3270 |   56  | 44·632 |
  | 1·3216 |   55  | 43·835 |
  | 1·3163 |   54  | 43·038 |
  | 1·3110 |   53  | 42·241 |
  | 1·3056 |   52  | 41·444 |
  | 1·3001 |   51  | 40·647 |
  | 1·2947 |   50  | 39·850 |
  | 1·2887 |   49  | 39·053 |
  | 1·2826 |   48  | 38·256 |
  | 1·2765 |   47  | 37·459 |
  | 1·2705 |   46  | 36·662 |
  | 1·2644 |   45  | 35·865 |
  | 1·2583 |   44  | 35·068 |
  | 1·2523 |   43  | 34·271 |
  | 1·2462 |   42  | 33·474 |
  | 1·2402 |   41  | 32·677 |
  | 1·2341 |   40  | 31·880 |
  | 1·2277 |   39  | 31·083 |
  | 1·2212 |   38  | 30·286 |
  | 1·2148 |   37  | 29·489 |
  | 1·2084 |   36  | 28·692 |
  | 1·2019 |   35  | 27·895 |
  | 1·1958 |   34  | 27·098 |
  | 1·1895 |   33  | 26·301 |
  | 1·1833 |   32  | 25·504 |
  | 1·1770 |   31  | 24·707 |
  | 1·1709 |   30  | 23·900 |
  | 1·1648 |   29  | 23·113 |
  | 1·1587 |   28  | 22·316 |
  | 1·1526 |   27  | 21·519 |
  | 1·1465 |   26  | 20·722 |
  | 1·1403 |   25  | 19·925 |
  | 1·1345 |   24  | 19·128 |
  | 1·1286 |   23  | 18·331 |
  | 1·1227 |   22  | 17·534 |
  | 1·1168 |   21  | 16·737 |
  | 1·1109 |   20  | 15·940 |
  | 1·1051 |   19  | 15·143 |
  | 1·0993 |   18  | 14·346 |
  | 1·0935 |   17  | 13·549 |
  | 1·0878 |   16  | 12·752 |
  | 1·0821 |   15  | 11·955 |
  | 1·0764 |   14  | 11·158 |
  | 1·0708 |   13  | 10·361 |
  | 1·0651 |   12  |  9·564 |
  | 1·0595 |   11  |  8·767 |
  | 1·0540 |   10  |  7·970 |
  | 1·0485 |    9  |  7·173 |
  | 1·0430 |    8  |  6·376 |
  | 1·0375 |    7  |  5·579 |
  | 1·0320 |    6  |  4·782 |
  | 1·0267 |    5  |  3·985 |
  | 1·0212 |    4  |  3·188 |
  | 1·0159 |    3  |  2·391 |
  | 1·0106 |    2  |  1·594 |
  | 1·0053 |    1  |  0·797 |
  +--------+-------+--------+


NITROGEN, DEUTOXIDE OF; _Nitrous gas_, _Nitric oxide_ (_Deutoxide
d’azote_, Fr.; _Stickstoffoxyd_, Germ.); is a gaseous body which may be
obtained by pouring upon copper or mercury, in a retort, nitric acid of
moderate strength. The nitrous gas comes over in abundance without the
aid of heat, and may be received over water freed from air, or over
mercury, in the pneumatic trough. It is elastic and colourless; what
taste and smell it possesses are unknown, because the moment it is
exposed to the mouth or nostrils, it absorbs atmospherical oxygen, and
becomes nitrous or nitric acid. Its specific gravity is 1·0393, or 1·04;
whence 100 cubic inches weigh 36·66 gr. Water condenses not more than
1/20 of its volume of this gas. It extinguishes animal life, and the
flame of many combustibles; but of phosphorus well kindled, it brightens
the flame in a most remarkable degree. It consists of 47 parts of
nitrogen gas, and 53 of oxygen gas, by weight; and of equal parts in
bulk, without any condensation; so that the specific gravity of
deutoxide of nitrogen is the arithmetical mean of the two constituents.
The constitution of this gas, and the play of affinities which it
exercises in the formation of sulphuric acid, are deeply interesting to
the chemical manufacturer.

_The Hyponitrous acid_ (_Salpetrigesaüre_, Germ.), like the preceding
compound, deserves notice here, on account of the part it plays in the
conversion of sulphur into sulphuric acid, by the agency of nitre. It is
formed by mingling four volumes of deutoxide of nitrogen with one volume
of oxygen; and appears as a dark orange vapour which is condensable into
a liquid at a temperature of 4° -zero, Fahr. When distilled, this liquid
leaves a dark yellow fluid. The pure hyponitrous acid consists of 37·12
nitrogen, and 62·88 oxygen; or of two volumes of the first, and three of
the second. Water converts it into nitric acid and deutoxide of
nitrogen; the latter of which escapes with effervescence. This acid
oxidizes most combustible bodies with peculiar energy and though its
vapour does not operate upon dry sulphurous acid, yet, through the
agency of steam it converts it into sulphuric acid, itself being
simultaneously transformed into deutoxide of nitrogen; ready to become
hyponitrous acid again, and to perform a circulating series of important
metamorphoses. See SULPHURIC ACID.


NITROGEN GAS, or AZOTE (Eng. and Fr.; _Stickstoffgas_, Germ.);
constitutes about 79 hundredths of the bulk of the atmospheric air; it
is copiously disengaged from several mineral springs, as from the
natural basins of hot water which supply the baths of Leuk, near the
Gemmi in Switzerland, and from other springs, in the Pyrenees, in
Ceylon, South and North America, &c. It exists also in flesh and most
animal substances, as well as in some vegetable products, being one of
their essential constituents. When phosphorus is burnt within a jar
filled with air, standing over water in the pneumatic trough, it
consumes or absorbs the oxygen, and leaves nitrogen, which may be
rendered pure by agitation with water. By exposing nitrite of ammonia to
heat in a retort, nitrogen comes over alone in great abundance; for the
hydrogen of the ammonia is sufficient to saturate the oxygen of the
acid, and to convert it into water; while the nitrogen of both
constituents is set at liberty. By transmitting chlorine through water
of ammonia, or digesting lean flesh in warm nitric acid, nitrogen may
also be obtained. This permanently elastic gas is destitute of colour,
taste, and smell; it has a specific gravity of 0·976, air being 1·000.
Hence 100 cubic inches of it weigh 29·7 gr. It extinguishes all burning
bodies, and when respired without oxygen is fatal to animal life.


NITROGEN, PROTOXIDE OF; _Nitrous oxide_ (_Protoxide d’azote_, Fr.;
_Stickstoffoxydul_, Germ.); is a gas which displays remarkable powers
when breathed, causing in many persons unrestrainable feelings of
exhilaration, whence it has been called the laughing or intoxicating
gas. It is prepared by exposing crystallized nitrate of ammonia to a
heat of about 350° Fahr., in a glass retort. It is much denser than the
air of the atmosphere, having a spec. grav. of 1·527; whence 100 cubic
inches weigh 46·6 grains. It consists of 63·64 parts of nitrogen, and
36·36 of oxygen, by weight; or of two volumes of nitrogen and one volume
of oxygen, condensed by reciprocal attraction into two volumes. It is
colourless, and possesses all the mechanical properties of the
atmosphere. Water previously freed from air absorbs its own volume of
this gas; and thus affords a ready criterion for estimating its freedom
from incondensable gases, as oxygen, nitrogen, and its deutoxide.
Several combustibles burn in this gas with an enlarged blue and very
vivid flame; and it relumes a taper, which has been blown out, provided
its tip be redhot. By powerful pressure it may be liquefied. See GAS.


NITRO-MURIATIC ACID, _Aqua regia_ (_Acide nitro-muriatique_, Fr.;
_Salpeter-salzsaüre, Königswasser_, Germ.); is the compound menstruum
invented by the alchemists for dissolving gold. If strong nitric acid,
orange-coloured by saturation with nitrous gas (deutoxide of azote), be
mixed with the strongest liquid muriatic acid, no other effect is
produced than might be expected from the action of nitrous acid of the
same strength upon an equal quantity of water; nor has the mixed acid so
formed, any power of acting upon gold or platina. But if colourless
aquafortis and ordinary muriatic acid be mixed together, the mixture
immediately becomes yellow, and acquires the power of dissolving these
two noble metals. When gently heated, pure chlorine gas rises from it,
and its colour becomes deeper; when further heated, chlorine still
rises, but now mixed with nitrous acid gas. If the process has been very
long continued, till the colour becomes very dark, no more chlorine can
be procured, and the liquor has lost the power of dissolving gold. It
then consists of nitrous and muriatic acids. It appears, therefore, that
aqua regia owes its peculiar properties to the mutual decomposition of
the nitric and muriatic acids; and that water, chlorine, and nitrous
acid gas are the results of that reaction. Aqua regia does not, strictly
speaking, oxidize gold and platinum; it causes merely their combination
with chlorine. It may be composed of very different proportions of the
two acids; the nitric being commonly of specific gravity 1·34; the
muriatic, of specific gravity 1·18 or 1·19. Sometimes 3 parts, and at
others 6 parts of the muriatic acid are mixed with 1 of nitric; and
occasionally muriate of ammonia, instead of muriatic acid, is added to
nitric acid for particular purposes, as for making a solution of tin for
the dyers. An aqua regia may also be prepared by dissolving nitre in
muriatic acid.


NITROUS ACID (_Acide nitreux_, Fr.; _Salpetrige salpetersaüre_, Germ.),
may be procured by distilling, in a coated glass retort, perfectly dry
nitrate of lead, into a glass receiver surrounded with a freezing
mixture. The acid passes over in vapour, and condenses into a liquid;
oxygen gas escapes through the safety tube; while oxide of lead remains
in the bottom of the retort. Nitrous acid may also be obtained by
distilling strong fuming nitric acid, at the lowest possible
temperature, and rectifying what comes over. At 4° -zero, Fahr., this
acid is colourless; at 32° it is wax yellow; at 60° it has an orange
hue. It possesses a strong smell, has a very pungent, acrid, sour taste,
and a specific gravity of 1·42. It powerfully decomposes organic bodies,
staining them yellow. It boils at 82° Fahr. with the disengagement of
red or orange fumes. Its constituents are, 41·34 of hyponitrous acid,
and 58·66 of anhydrous nitric acid; or ultimately, 30·68 nitrogen = 1
volume, and 69·32 oxygen = 2 volumes. In its other habitudes, it is
quite analogous to hyponitrous acid.

A mixture of this double or compound acid with nitric acid, constitutes
the orange-brown fuming nitrous acid of the British apothecaries.

The hyponitrous and nitrous are two acids remarkable for containing no
water in their composition; being therefore _dry liquids_.


NOPAL, is the Mexican name of the plant _cactus opuntia_, upon which the
cochineal insect breeds.


NUTMEG (_Muscade_, Fr.; _Muskatennuss_, Germ.); is the fruit of the
_myristica moschata_, a beautiful tree of the family of the _laurineæ_
of Jussieu, which grows in the Molucca islands. All the parts of this
tree are very aromatic; but only those portions of the fruit called mace
and nutmeg are sent into the market. The entire fruit is a species of
_drupa_, of an ovoid form, of the size of a peach, and furrowed
longitudinally. The nutmeg is the innermost kernel, or seed, contained
in a thin shell, which is surrounded by the mace; and this again is
enclosed in a tough fleshy skin, which opening at the tip, separates
into two valves. The nutmeg tree yields three crops annually; one in
April, which is the best; one in August; and one in December.

Good nutmegs should be dense, and feel heavy in the hand. When they have
been perforated by worms, they feel light, and though the holes have
been fraudulently stopped, the unsound ones may be easily detected by
this criterion.

_Nutmegs_ afford two oily products. 1. Butter of nutmeg, vulgarly called
oil of mace, is obtained in the Moluccas, by expression, from the fresh
nutmegs, to the amount of 50 per cent. of their weight. It is a reddish
yellow butter-like substance, interspersed with light and dark streaks,
and possesses the agreeable smell and taste of the nutmeg, from the
presence of a volatile oil. It consists of two fats; one reddish and
soft, soluble in cold alcohol; another white and solid, soluble in hot
alcohol. 2. The volatile oil is solid, or a _stereoptène_, and has been
styled _Myristicine_.


NUT OIL. See OILS, UNCTUOUS.


NUX VOMICA, a poisonous nut, remarkable for containing the vegeto-alkali
STRYCHNIA.




O.


OAK BARK. See TAN.


OATS. (_Avoine_, Fr.; _Hafer_, Germ.) The composition of oats is less
known than that of the other _Cerealia_. Vogel found that 100 parts of
oats afforded 66 parts of flour or meal, and 34 parts of bran; but this
proportion would depend upon the quality of the grain. The flour
contains, 2 parts of a greenish-yellow fat oil; 8·25 of bitterish sweet
extractive; 2·5 of gum; 4·30 of a gray substance, more like coagulated
albumen than gluten; 59 of starch; 24 of moisture (inclusive of the
loss). Schrader found in the ashes of oats, silica, carbonate of lime,
carbonate of magnesia, alumina, with oxides of manganese and iron.


OBSIDIAN, is a glassy looking mineral, with a large conchoidal fracture,
and of a blackish colour, which froths much at the blow-pipe before it
melts into a white enamel.


OCHRE, _yellow and brown_ (_Ocre_, Fr.; _Ocker_, Germ.); is a native
earthy mixture of silica and alumina, coloured by oxide of iron, with
occasionally a little calcareous matter and magnesia. Ochre occurs in
beds some feet thick, which lie generally above the oolite, are covered
by sandstone and quartzose sands more or less ferruginous, and are
accompanied by gray plastic clays, of a yellowish or reddish colour; all
of them substances which contribute more or less to its formation. The
ochry earths are prepared for use by grinding under edge millstones, and
elutriation. The yellow ochres may be easily rendered red or reddish
brown by calcination in a reverberatory oven, which oxidizes their iron
to a higher degree.

Native red ochre is called red chalk and reddle in England. It is an
intimate mixture of clay and red iron ochre; is massive; of an earthy
fracture; is brownish-red, blood-red, stains and writes red. The oxide
of iron is sometimes so considerable, that the ochre may be reckoned an
ore of that metal.

The ochre beds of England are in the iron sand, the lowest of the
formations which intervene between the chalk and oolites. Beds of
fuller’s earth alternate with the iron sand. The following is a section
of the ochre pits at Shotover Hill, near Oxford:--

  Beds of highly ferruginous grit, forming the
  summit of the hill                              6    feet.
  Gray sand                                       3     do.
  Ferruginous concretions                         1
  Yellow sand                                     6
  Cream-coloured loam                             4
  Ochre                                           0  6 inches.

Beneath this, there is a second bed of ochre, separated by a thin bed of
clay.

Bole, or Armenian bole; called also Lemnian earth, and terra sigillata,
because when refined it was stamped with a seal; is massive, with a
conchoidal fracture, a feeble lustre, reddish-yellow or brown, a greasy
feel; adheres to the tongue, spec. gray. 1·4 to 2·0. It occurs in the
island Stalimene (the ancient Lesbos), and in several other places,
especially at Sienna; whence the brown pigment called _terra di Siena_.


OILS (_Huiles_, Fr.; _Oele_, Germ.); are divisible into two great
classes: the fat or fixed oils, _huiles grasses_, Fr.; _Fette oele_,
Germ.; and the essential or volatile oils, _Huiles volatiles_, Fr.;
_Flüchtige_, _aetherische oele_, Germ. The former are usually bland and
mild to the taste; the latter hot and pungent. The term distilled,
applied also to the last class, is not so correct, since some of them
are obtained by expression, as the whole of the first class may be, and
commonly are.

All the known fatty substances found in organic bodies, without
reference to their vegetable or animal origin, are, according to their
consistence, arranged under the chemical heads of oils, butters, and
tallows. They all possess the same ultimate constituents, carbon,
hydrogen, and generally oxygen, and in nearly the same proportions.

The fat oils are widely distributed through the organs of vegetable and
animal nature. They are found in the seeds of many plants, associated
with mucilage, especially in those of the bicotyledinous class,
occasionally in the fleshy pulp surrounding some seeds, as the olive;
also in the kernels of many fruits, as of the nut and almond tree, and
finally in the roots, barks, and other parts of plants. In animal
bodies, the oily matter occurs enclosed in thin membranous cells,
between the skin and the flesh, between the muscular fibres, within the
abdominal cavity in the omentum, upon the intestines, and round the
kidneys, and in a bony receptacle of the skull of the spermaceti whale;
sometimes in special organs, as of the beaver; in the gall-bladder, &c.,
or mixed in a liquid state with other animal matters, as in the milk.

Braconnot, but particularly Raspail, have shown that animal fats consist
of small microscopic, partly polygonal, and partly reniform particles,
associated by means of their containing sacs. These may be separated
from each other by tearing the recent fat asunder, rinsing it with
water, and passing it through a sieve. The membranes being thus
retained, the granular particles are observed to float in the water, and
afterwards to separate, like the globules of starch, in a white
pulverulent semi-crystalline form. The particles consist of a strong
membranous skin, enclosing _stearine and elaine_, or solid and liquid
fat, which may be extracted by trituration and pressure. These are
lighter than water, but sink readily in spirit of wine. When boiled in
strong alcohol, the oily principle dissolves, but the fatty membrane
remains. These granules have different sizes and shapes in different
animals; in the calf, the ox, the sheep, they are polygonal, and from
1/70 to 1/450 of an inch in diameter; in the hog they are kidney-shaped,
and from 1/70 to 1/140 of an inch; in man, they are polygonal, and from
1/70 to 1/900 of an inch; in insects they are usually spherical, and not
more than 1/600 of an inch.

The following is a list of the Plants which yield the ordinary Unctuous
Oils of commerce:

  +---+--------------------------------+---------------------+--------+
  |No.|            Plants.             |        Oils.        |Specific|
  |   |                                |                     |gravity.|
  +---+--------------------------------+---------------------+--------+
  | 1.|Linum usitatissum et perenne  D.|Linseed oil          | 0·9347 |
  | 2.|Coryleus avellana }           D.|Nut oil              | 0·9260 |
  | 3.|Juglans regia     }             |                     |        |
  | 4.|Papaver somniferum            D.|Poppy oil            | 0·9243 |
  | 5.|Cannabis sativa               D.|Hemp oil             | 0·9276 |
  | 6.|Sesamum orientale             G.|Oil of sesamum       |        |
  | 7.|Olea Europea                  G.|Olive oil            | 0·9176 |
  | 8.|Amygdalus communis            G.|Almond oil           | 0·9180 |
  | 9.|Guilandina mohringa           G.|Oil of behen or ben  |        |
  |10.|Cucurbita pepo, and melapepo  D.|Cucumber oil         | 0·9231 |
  |11.|Fagus silvatica               G.|Beech oil            | 0·9225 |
  |12.|Sinapis nigra et arvensis     G.|Oil of mustard       | 0·9160 |
  |13.|Helianthus annuus et perennis D.|Oil of sunflower     | 0·9262 |
  |14.|Brassica napus et campestris  G.|Rape seed oil        | 0·9136 |
  |15.|Ricinus communis              D.|Castor oil           | 0·9611 |
  |16.|Nicotiana tabacum et rustica  D.|Tobacco seed oil     | 0·9232 |
  |17.|Prunus domestica              G.|Plum kernel oil      | 0·9127 |
  |18.|Vitis vinifera                D.|Grape seed oil       | 0·9202 |
  |19.|Theobroma cacao               G.|Butter of cacao      | 0·892  |
  |20.|Cocos nucifera                G.|Cocoa nut oil        |        |
  |21.|Cocus butyracea vel avoira      |                     |        |
  |   |elais                         G.|Palm oil             | 0·968  |
  |22.|Laurus nobilis                G.|Laurel oil           |        |
  |23.|Arachis hypogæa               G.|Ground-nut oil       |        |
  |24.|Vateria indica                G.|Piney tallow         | 0·926  |
  |25.|Hesperis matronalis           D.|Oil of Julienne      | 0·9281 |
  |26.|Myagrum sativa                D.|Oil of camelina      | 0·9252 |
  |27.|Reseda luteola                D.|Oil of weld-seed     | 0·9358 |
  |28.|Lepidium sativum              D.|Oil of garden cresses| 0·9240 |
  |29.|Atropa belladonna             D.|Oil of deadly        |        |
  |   |                                |nightshade           | 0·9250 |
  |30.|Gossypium Barbadense          D.|Cotton seed oil      |        |
  |31.|Brassica campestris oleifera  G.|Colza oil            | 0·9136 |
  |32.|Brassica præcox               G.|Summer rapeseed oil  | 0·9139 |
  |33.|Raphanus sativus oleifer      G.|Oil of radish seed   | 0·9187 |
  |34.|Prunus cerasus                G.|Cherry-stone oil     | 0·9239 |
  |35.|Pyrus malus                   G.|Apple seed oil       |        |
  |36.|Euonymus Europæus             G.|Spindle tree oil     | 0·9380 |
  |37.|Cornus sanguinea              G.|Cornil berry tree oil|        |
  |38.|Cyperus esculenta             G.|Oil of the roots of  |        |
  |   |                                |cyper grass          | 0·9180 |
  |39.|Hyosciamus niger              G.|Henbane seed oil     | 0·9130 |
  |40.|Æsculus hippocastanum         G.|Horse chesnut oil    | 0·927  |
  |41.|Pinus abies                   D.|Pinetop oil          | 028 5  |
  +---+--------------------------------+---------------------+--------+

The fat oils are contained in that part of the seed which gives birth to
the cotyledons; they are not found in the plumula and radicle. Of all
the families of plants, the cruciform is the richest in oleiferous
seeds; and next to that, are the drupaceæ, amentaceæ, and solaneæ. The
seeds of the gramineæ and leguminosæ contain rarely more than a trace of
fat oil. One root alone, that of the _cyperus esculenta_, contains a fat
oil. The quantity of oil furnished by seeds varies not only with the
species, but in the same seed, with culture and climate. Nuts contain
about half their weight of oil; the seeds of the _brassica oleracea and
campestris_, one third; the variety called colza in France, two fifths;
hempseed, one fourth; and linseed from one fourth to one fifth.
Unverdorben states that a last, or ten quarters, of linseed, yields 40
ahms = 120 gallons English of oil; which is about 1 cwt. of oil per
quarter.

The fat oils, when first expressed without much heat, taste merely
unctuous on the tongue, and exhale the odour of their respective plants.
They appear quite neutral by litmus paper. Their fluidity is very
various, some being solid at ordinary temperatures, and others remaining
fluid at the freezing point of water. Linseed oil indeed does not
congeal till cooled from 4° to 18° below 0° F. The same kind of seed
usually affords oils of different degrees of fusibility; so that in the
progress of refrigeration one portion concretes before another.
Chevreul, who was the first to observe this fact, considers all the oils
to be composed of two species, one of which resembles _suet_, and was
thence styled by him _stearine_; and another which is liquid at ordinary
temperatures, and was called _elaine_, or _oleine_. By refrigeration and
pressure between the folds of blotting paper, or in linen bags, the
fluid part is separated, and the solid remains. By heating the paper in
water, the liquid oil may be obtained separate. When alcohol is boiled
with the natural oil, the greater part of the stearine remains
undissolved.

Oleine may also be procured by digesting the oil with a quantity of
caustic soda equal to one half of what is requisite to saponify the
whole; the stearine is first transformed into soap, then a portion of
the oleine undergoes the same change, but a great part of it remains in
a pure state. This process succeeds only with recently expressed or very
fresh oils. The properties of these two principles of the fat oils vary
with the nature of the respective oils, so that the sole difference does
not consist, as many suppose, in the different proportions of these two
bodies, but also in peculiarities of the several stearines and oleines,
which, as extracted from different seeds, solidify at very different
temperatures.

In close vessels, oils may be preserved fresh for a very long time, but
with contact of air they undergo progressive changes. Certain oils
thicken and eventually dry into a transparent, yellowish, flexible
substance; which forms a skin upon the surface of the oil, and retards
its further alteration. Such oils are said to be _drying_ or
_siccative_, and are used on this account in the preparation of
varnishes and painters’ colours. Other oils do not grow dry, though they
turn thick, become less combustible, and assume an offensive smell. They
are then called _rancid_. In this state, they exhibit an acid reaction,
and irritate the fauces when swallowed, in consequence of the presence
of a peculiar acid, which may be removed in a great measure by boiling
the oil along with water and a little common magnesia for a quarter of
an hour, or till it has lost the property of reddening litmus. While
oils undergo the above changes, they absorb a quantity of oxygen equal
to several times their volume. Saussure found that a layer of nut oil,
one-quarter of an inch thick, enclosed along with oxygen gas over the
surface of quicksilver in the shade, absorbed only three times its bulk
of that gas in the course of eight months; but when exposed to the sun
in August, it absorbed 60 volumes additional in the course of ten days.
This absorption of oxygen diminished progressively, and stopped
altogether at the end of three months, when it had amounted to 145 times
the bulk of the oil. No water was generated, but 21·9 volumes of
carbonic acid were disengaged, while the oil was transformed in an
anomalous manner into a gelatinous mass, which did not stain paper. To a
like absorption we may ascribe the elevation of temperature which
happens when wool or hemp, besmeared with olive or rapeseed oil, is left
in a heap; circumstances under which it has frequently taken fire, and
caused the destruction of both cloth-mills and dock-yards.

In illustration of these accidents, if paper, linen, tow, wool, cotton,
mats, straw, wood shavings, moss, or soot, be imbued slightly with
linseed or hempseed oil, and placed in contact with the sun and air,
especially when wrapped or piled in a heap, they very soon become
spontaneously hot, emit smoke, and finally burst into flames. If linseed
oil and ground manganese be triturated together, the soft lump so formed
will speedily become firm, and ere long take fire.

The fat oils are completely insoluble in water. When agitated with it,
the mixture becomes turbid, but if it be allowed to settle the oil
collects by itself upon the surface. This method of washing is often
employed to purify oils. Oils are little soluble in alcohol, except at
high temperatures. Castor oil is the only one which dissolves in cold
alcohol. Ether, however, is an excellent solvent of oils, and is
therefore employed to extract them from other bodies in analysis; after
which it is withdrawn by distillation.

Fat oils may be exposed to a considerably high temperature, without
undergoing much alteration; but when they are raised to nearly their
boiling point, they begin to be decomposed. The vapours that then rise
are not the oil itself, but certain products generated in it by the
heat. These changes begin somewhere under 600° of Fahr., and require for
their continuance temperatures always increasing. The products consist
at first in aqueous vapour, then a very inflammable volatile oil, which
causes boiling oil to take fire spontaneously; and next carburetted
hydrogen gas, with carbonic acid gas. In a lamp, a small portion of oil
is raised in the wick by capillarity, which being heated, boils and
burns. See ROSIN-GAS.

Several fat oils, mixed with one or two per cent. of sulphuric acid,
assume instantly a dark green or brown hue, and, when allowed to stand
quietly, deposit a colouring matter after some time. It consists in a
chemical combination of the sulphuric acid, with a body thus separated
from the oil, which becomes in consequence more limpid, and burns with a
brighter flame, especially after it is washed with steam, and clarified
by repose or filtration. Any remaining moisture may be expelled by the
heat of a water bath.

The oils combine with the salifiable bases, and give birth to the
substance called _glycerine_ (the sweet principle), and to the margaric,
oleic, and stearic acids. The general product of their combination with
potash or soda, is SOAP, which see. Caustic ammonia changes the oils
very difficultly and slowly into a soap; but it readily unites with them
into a milky emulsion called volatile liniment, used as a rubefacient
in medicine. Upon mixing water with this liquor, the oil separates in
an unchanged state. By longer contact, ammonia acts upon oils like the
other alkalis. Sea salt dissolves in small quantity in the oils, and so
does verdigris. The latter solution is green. Oils dissolve also several
of the vegetable alkalis, as morphia, cinchonia, quinia, strychia, and
delphia.

Olive oil consists of 77·2 carbon, 13·4 hydrogen, and 9·4 oxygen, in 100
parts. Spermaceti oil, by my analysis, of 78·9 carbon, 10·97 hydrogen,
and 10·13 oxygen.

  Castor oil  do.        74·0    10·3    15·7    azote,
  Stearine of olive oil  82·17   11·23    6·30   0·30   _Saussure_.
  Oleine of  do.         76·03   11·54   12·07   0·35       do.
  Linseed oil            76·01   11·35   12·64              do.
  Nut oil                79·77   10·57    9·12   0·54       do.
  Oil of almonds         77·40   11·48   10·83   0·29

De Saussure concludes that the less fusible fats contain more carbon and
less oxygen, and that oils are more soluble in alcohol, the more oxygen
they contain.

I shall now take a short view of the peculiarities of the principal
expressed oils.

_Oil of almonds_, according to Gusseron, contains no stearine; at least
he could obtain none by cooling it and squeezing it successively till it
all congealed. Braconnot had, on the contrary, said, that it contains 24
per cent. of stearine. I believe that Gusseron is right, and that
Braconnot had made fallacious experiments on an impure oil.

_Oil of colza_, is obtained from the seeds of _brassica campestris_, to
the amount of 39 per cent. of their weight. It forms an excellent lamp
oil, and is much employed in France.

The _corylus avellana_ furnishes in oil 60 per cent. of the weight of
the nuts.

_Hempseed oil_, resembles the preceding, but has a disagreeable smell,
and a mawkish taste. It is used extensively for making both soft soap
and varnishes.

_Linseed oil_, is obtained in greatest purity by cold pressure; but by a
steam heat of about 200° F. a very good oil may be procured in larger
quantity. The proportion of oil usually stated by authors is 22 per
cent. of the weight of the seed; but Mr. Blundell informs me, that, by
his plan of hydraulic pressure, he obtains from 26 to 27. In the
Encyclopædia Metropolitana, under _Oil Press_, a quarter of seed (whose
average weight is 400 lbs.) is said to yield 20 gallons of oil. Now as
the gallon of linseed oil weighs 9·3 lbs., the total product will be 186
lbs., which amounts to more than 45 per cent.--an extravagant statement,
about double the ordinary product in oil mills. Even supposing the
gallons not to be imperial, but old English, we should have upwards of
38 per cent. of oil by weight, which is still an impossible quantity.
Such are the errors introduced into respectable books, by adopting
without practical knowledge, the puffing statements of a patentee. It
dissolves in 5 parts of boiling alcohol, in 40 parts of cold alcohol,
and in 1·6 parts of ether. When kept long cool in a cask partly open, it
deposits masses of white stearine along with a brownish powder. That
stearine is very difficult of saponification.

_Mustard-seed oil._ The white or yellow seed affords 36 per cent. of
oil, and the black seed 18 per cent. The oil concretes when cooled a
little below 32° F.

_Nut oil_, is at first greenish coloured, but becomes pale yellow by
time. It congeals at the same low temperature as linseed oil, into a
white mass, and has a more drying quality than it.

_Oil of olives_, is sometimes of a greenish and at others of a pale
yellow colour. A few degrees above 32° F. it begins to deposit some
white granules of stearine, especially if the oil have been originally
expressed with heat. At 22° it deposits 28 per cent. of its weight in
stearine, which is fusible again at 68°, and affords 72 per cent. of
oleine. According to Kerwych, oleine of singular beauty may be obtained
by mixing 2 parts of olive oil with 1 part of caustic soda lye, and
macerating the mixture for 24 hours with frequent agitation. Weak
alcohol must then be poured into it, to dissolve the stearine soap,
whereby the oleine, which remains meanwhile unsaponified, is separated,
and floats on the surface of the liquid. This being drawn off, a fresh
quantity of spirits is to be poured in, till the separation of all the
oleine be completed. It has a slightly yellowish tint, which may be
removed by means of a little animal charcoal mixed with it in a warm
place for 24 hours. By subsequent nitration, the oleine is obtained
limpid and colourless, of such quality that it does not thicken with the
greatest cold, nor does it affect either iron or copper instruments
immersed in it.

There are three kinds of olive oil in the market. The best, called
virgin salad oil, is obtained by a gentle pressure in the cold; the more
common sort is procured by stronger pressure, aided with the heat of
boiling water; and thirdly, an inferior kind, by boiling the olive
residuum or _marc_, with water, whereby a good deal of mucilaginous oil
rises and floats on the surface. The latter serves chiefly for making
soaps. A still worse oil is got by allowing the mass of bruised olives
to ferment before subjecting it to pressure.

Oil of olives is refined for the watchmakers by the following simple
process. Into a bottle or phial containing it, a slip of sheet lead is
immersed, and the bottle is placed at a window, where it may receive the
rays of the sun. The oil by degrees gets covered with a curdy mass,
which after some time settles to the bottom, while itself becomes limpid
and colourless. As soon as the lead ceases to separate any more of that
white substance, the oil is decanted off into another phial for use.

_Palm oil_ melts at 117·5° F., and is said to consist of 31 parts of
stearine and 69 of oleine in 100. It becomes readily rancid by exposure
to air, and is whitened at the same time.

The oil extracted from the plucked tops of the _pinus abies_, in the
Black Forest in Germany, is limpid, of a golden yellow colour, and
resembles in smell and taste the oil of turpentine. It answers well for
the preparation of varnishes.

The _oil of plum-stones_, is made chiefly in Wurtemberg, and is found to
answer very well for lamps.

_Poppy-seed oil_, has none of the narcotic properties of the poppy
juice. It is soluble in ether in every proportion.

_Rape-seed oil_, has a yellow colour, and a peculiar smell. At 25° F. it
becomes a yellow mass, consisting of 46 parts of stearine, which fuses
at 50°, and 54 of oleine, in which the smell resides.

The _oils of belladonna seeds_, and _tobacco seeds_, are perfectly
bland. The former is much used for lamps in Swabia and Wurtemberg. The
oil-cakes of both are poisonous.

_Oil of wine-stones_, is extracted to the amount of 10 or 11 per cent.
from the seeds of the grape. Its colour is at first pale yellow, but it
darkens with age. It is used as an article of diet.

FAT OIL MANUFACTURE.

It is the practice of almost all the proprietors in the neighbourhood of
Aix, in Provence, to preserve the olives for 15 days in barns or
cellars, till they have undergone a species of fermentation, in order to
facilitate the extraction of their oil. If this practice were really
prejudicial to the product, as some theorists have said, would not the
high reputation and price of the oil of Aix have long ago suffered, and
have induced them to change their system of working? In fact all depends
upon the degree of fermentation excited. They must not be allowed to
mould in damp places, to lie in heaps, to soften so as to stick to each
other, and discharge a reddish liquor, or to become so hot as to raise a
thermometer plunged into the mass up to 96° F. In such a case they would
afford an acrid nauseous oil, fit only for the woollen or soap
manufactories. A slight fermentative action, however, is useful, towards
separating the oil from the mucilage. The olives are then crushed under
the stones of an edge-mill, and next put into a screw-press, being
enclosed in bullrush-mat bags (_cabas_), laid over each other to the
number of eighteen. The oil is run off from the channels of the
ground-sill, into casks, or into stone cisterns called _pizes_,
two-thirds filled with water. The pressure applied to the _cabas_ should
be slowly graduated.

What comes over first, without heat, is the virgin oil already
mentioned. The _cabas_ being now removed from the press, their contents
are shovelled out, mixed with some boiling water, again put in the bags,
and pressed anew. The hot water helps to carry off the oil, which is
received in other casks or _pizes_. The oil ere long accumulates at the
surface, and is skimmed off with large flat ladles; a process which is
called _lever l’huile_. When used fresh, this is a very good article,
and quite fit for table use, but is apt to get rancid when kept. The
subjacent water retains a good deal of oil, by the intervention of the
mucilage; but by long repose in a large general cistern, called
_l’enfer_, it parts with it, and is then drawn off from the bottom by a
plug-hole. The oil which remains after the water is run off, is of an
inferior quality, and can be used only for factory purposes.

The marc being crushed in a mill, boiled with water, and expressed,
yields a still coarser article.

All the oil must be _fined_ by keeping in clean tuns, in an apartment,
heated to the 60th degree Fahr. at least, for twenty days; after which
it is run off into strong casks, which are cooled in a cellar, and then
sent into the market.

_Oil of almonds_, is manufactured by agitating the kernels in bags, so
as to separate their brown skins, grinding them in a mill, then
enclosing them in bags, and squeezing them strongly between a series of
cast iron plates, in a hydraulic press; without heat at first, and then
between heated plates. The first oil is the purest, and least apt to
become rancid. It should be refined by filtering through porous paper.
Next to olive oil, this species is the most easy to saponify. Bitter
almonds being cheaper than the sweet, are used in preference for
obtaining this oil, and they afford an article equally bland, wholesome,
and inodorous. But a strongly scented oil may be procured, according to
M. Planché, by macerating the almonds in hot water, so as to blanch
them, then drying them in a stove, and afterwards subjecting them to
pressure. The volatile oil of almonds is obtained by distilling the marc
or bitter almond cake, along with water. See PRESS, HYDRAULIC, and
STEARINE.

Linseed, rapeseed, poppyseed, and other oleiferous seeds were formerly
treated for the extraction of their oil, by pounding in hard wooden
mortars with pestles shod with iron, set in motion by cams driven by a
shaft turned with horse or water power, then the triturated seed was put
into woollen bags which were wrapped up in hair-cloths, and squeezed
between upright wedges in press-boxes by the impulsion of vertical rams
driven also by a cam mechanism. In the best mills upon the old
construction, the cakes obtained by this first wedge pressure, were
thrown upon the bed of an edge-mill, ground anew, and subjected to a
second pressure, aided by heat now, as in the first case. These mortars
and press-boxes constitute what are called Dutch mills. They are still
in very general use both in this country and on the Continent; and are
by many persons supposed to be preferable to the hydraulic presses.

[Illustration: 770 771]

The roller-mill, for merely bruising the linseed, &c., previous to
grinding it under edge-stones, and to heating and crushing it in a Dutch
or a hydraulic oil-mill, is represented in _figs._ 770. and 771. The
iron shaft _a_, has a winch at each end, with a heavy fly-wheel upon the
one of them, when the machine is to be worked by hand. Upon the opposite
end is a pulley, with an endless cord which passes round a pulley on the
end of the fluted roller _b_, and thereby drives it. This fluted roller
_b_, lies across the hopper _c_, and by its agitation causes the seeds
to descend equably through the hopper, between the crushing rollers _d_,
_e_. Upon the shaft _a_, there is also a pinion which works into two
toothed wheels on the shafts of the crushing cylinders _d_ and _e_, thus
communicating to these cylinders motion in opposite directions. _f_, _g_
are two scraper-blades, which by means of the two weights _h_, _h_,
hanging upon levers, are pressed against the surfaces of the cylinders,
and remove any seed-cake from them. The bruised seeds fall through the
slit _i_ of the case, and are received into a chest which stands upon
the board _k_.

Machines of this kind are now usually driven by power. Hydraulic presses
have been of late years introduced into many seed-oil mills in this
country; but it is still a matter of dispute whether they, or the old
Dutch oil-mill, with bags of seed compressed between wedges, driven by
cam-stamps, be the preferable; that is, afford the largest product of
oil with the same expenditure of capital and power. For figures of
hydraulic presses, see PRESS, and STEARINE.

This bruising of the seed is merely a preparation for its proper
grinding under a pair of heavy edge-stones, of granite, from 5 to 7 feet
in diameter; because unbruised seed is apt to slide away before the
vertical rolling wheel, and thus escape trituration. The edge-mill, for
grinding seeds, is quite analogous to the gunpowder-mill represented in
_fig._ 531., page 630. Some hoop the stones with an iron rim, but others
prefer, and I think justly, the rough surface of granite, and dress it
from time to time with hammers, as it becomes irregular. These stones
make from 30 to 36 revolutions upon their horizontal bed of masonry or
iron in a minute. The centre of the bed, where it is perforated for the
passage of the strong vertical shaft which turns the stones, is enclosed
by a circular box of cast iron, firmly bolted to the bed-stone, and
furnished with a cover. This box serves to prevent any seeds or powder
getting into the step or socket, and obstructing the movement. The
circumference of the mill-bed is formed of an upright rim of oak-plank,
bound with iron. There is a rectangular notch left in the edge of the
bed, and corresponding part of the rim, which is usually closed with a
slide-plate, and is opened only at the end of the operation, to let the
pasty seed-cake be turned out by the oblique arm of the bottom scraper.
The two parallel stones, which are set near each other, and travel round
their circular path upon the bed, grind the seeds not merely by their
weight, of three tons each, but also by a rubbing motion, or attrition;
because their periphery being not conical, but cylindrical, by its
rolling upon a plane surface, must at every instant turn round with
friction upon their resting points. Strong cast-iron boxes are bolted
upon the centres of the stones, which by means of screw clamps seize
firmly the horizontal iron shafts that traverse and drive them, by
passing into a slit-groove in the vertical turning shaft. This groove is
lined with strong plates of steel, which wear rapidly by the friction,
and need to be frequently renewed.

The seeds which have been burst between the rolls, or in the mortars of
the Dutch mills, are to be spread as equably as possible by a shovel
upon the circular path of the edge-stones, and in about half an hour the
charge will be sufficiently ground into a paste. This should be put
directly into the press, when fine cold-drawn oil is wanted. But in
general the paste is heated before being subjected to the pressure. The
pressed cake is again thrown under the edge-stones, and, after being
ground the second time, should be exposed to a heat of 212° Fahr., in a
proper pan, called a steam-kettle, before being subjected to the second
and final pressure in the woollen bags and hair-cloths.

[Illustration: 772 773]

_Fig._ 772. is a vertical section of the steam-kettle of Hallette, and
_fig._ 773. is a view of the seed-stirrer. _a_, is the wall of masonry,
upon which, and the iron pillars _b_, the pan is supported. It is
enclosed in a jacket, for admitting steam into the intermediate space
_d_, _d_, _d_, at its sides and bottom. _c_, is the middle of the pan in
which the shaft of the stirrer is planted upright, resting by its lower
end in the step _e_; _f_, is an opening, by which the contents of the
pan may be emptied; _g_, is an orifice into which the mouth of the hair
or worsted bag is inserted, in order to receive the heated seed, when it
is turned out by the rotation of the stirrer and the withdrawal of the
plug _f_ from the discharge aperture; _h_, is the steam induction pipe;
and _t_, the eduction pipe, which serves also to run off the condensed
water.

The hydraulic oil-press is generally double; that is, it has two
vertical rams placed parallel to each other, so that while one side is
under pressure, the other side is being discharged. The bags of heated
seed-paste or meal are put into cast-iron cases, which are piled over
each other to the number of 6 or 8, upon the press sill, and subjected
to a force of 300 or 400 tons, by pumps worked with a steam engine. The
first pump has usually 2 or 2-1/2 inches diameter for a ram of 10
inches, and the second pump one inch. Each side of the press, in a
well-going establishment, should work 38 pounds of seed-flour every 5
minutes. Such a press will do 70 quarters of linseed in the days’ work
of one week, with the labour of one man at 20_s._ and three boys at
5_s._ each; and will require a 12-horse power to work it well, along
with the rolls and the edge-stones.

I am indebted to my excellent friend Mr. E. Woolsey, for the following
most valuable notes, taken by him at sundry mills for pressing oil; and
remarks upon the subject of seed-crushing in general.

“The chief point of difference depends upon the quality of seed
employed. Heavy seed will yield most oil, and seed ripened under a hot
sun, and where the flax is not gathered too green, is the best. The
weight of linseed varies from 48 to 52 lbs. per imperial bushel;
probably a very fair average is 49 lbs., or 392 lbs. per imperial
quarter. I inspected one of the seed-crusher’s books, and the average of
15 trials of a quarter each of different seeds in the season averaged
14-1/2 galls. of 7-1/2 lbs. each; say, 109 lbs. of oil per quarter. This
crusher, who uses only the hydraulic press, and one pressing, informed
me that

  Archangel seed will yield
  from                         15 to 16 galls. (of 7-1/2 lbs. each)
  Best Odessa                                   18 and even 19 galls.
  Good crushing-seed                            15-1/2          do.
  Low seed, such as weighs 48
  lbs. per bushel              13-1/2                           do.

“The average of the seed he has worked, which he represents to be of an
inferior quality, for the sake of its cheapness, yields 14-1/2 galls.
per quarter. I had some American seed which weighed 52-1/4 lbs. per
imperial bushel, ground and pressed under my own observation, and it
gave me 111 lbs. oil; that is to say, 418 lbs. of seed gave 111 lbs. oil
= 26-56/100 per cent. A friend of mine, who is a London crusher, told me
the oil varied according to the seed from 14 to 17 galls.; and when you
consider the relative value of seeds, and remember that _oil_ and _cake_
from any kind of seed is of the _same value_, it will be apparent that
the yield is very different; for example,

  25th July, 1836,  {E. India linseed worth 52_s._       per quarter.
  prices of seed.   {Petersburg linseed     48     to 52      do.
                    {Odessa                 52      --        --

The difference of 4_s._ must be paid for in the quantity of oil which at
38_s._ 6_d._ per cwt. (the then price) requires about 11-1/2 lbs. more
oil expressed to pay for the difference in the market value of the seed.
Another London crusher informed me that East India linseed will produce
17 gallons, and he seemed to think that that was the extreme quantity
that could be expressed from _any seed_. The average of last year’s
Russian seed would be about 14 galls.; Sicilian seed 16 galls.

  +------+---------------+------------+---------+-------------+
  |Place.|Engine Power.  |Hydraulic   |Stampers.|Rollers.     |
  |      |               |Presses.    |         |             |
  +------+---------------+------------+---------+-------------+
  |France|10 horse power |1 hydraulic,|5 light  |1 pair rolls.|
  |      |               |200 tons.   |stampers.|             |
  |London|20 horse power |1 hydraulic,|13 light |1 pair rolls.|
  |      |               |800 tons.   |stampers.|             |
  |London|12 horse power,|none        |9 light  |2 pair rolls,|
  |      |but the engine |            |stampers.|used also for|
  |      |is used also   |            |         |other pur-   |
  |      |for other work.|            |         |poses.       |
  |Hull  |18 horse       |none        |3 very   |1 pair rolls.|
  |      |engine, old    |            |heavy    |             |
  |      |construction.  |            |stampers.|             |
  |Ditto |22 horse engine|none        |6 very   |2 pair rolls.|
  |      |               |            |heavy    |             |
  |      |               |            |stampers.|             |
  +------+---------------+------------+---------+-------------+

  +------+------------+---------------+-------------+------------+
  |Place.|Edge-stones.|Kettles.       |Work done,-- |Number of   |
  |      |            |               |reduced to an|pressings.  |
  |      |            |               |hour.        |            |
  +------+------------+---------------+-------------+------------+
  |France|1 pr. edge- |5 table kettles|1 English    |2 pressings.|
  |      |stones.     |small size     |quarter per  |            |
  |      |            |heated by      |working hour.|            |
  |      |            |steam.         |             |            |
  |London|2 pr. edge- |8 table kettles|2 English    |2 ditto     |
  |      |stones.     |small size     |quarters per |            |
  |      |            |heated by fire.|working hour.|            |
  |London|2 pr. edge- |4 table kettles|7/8 English  |2 ditto     |
  |      |stones, used|small size     |quarter per  |            |
  |      |also for    |heated by fire.|working hour.|            |
  |      |other pur-  |               |             |            |
  |      |poses.      |               |             |            |
  |Hull  |1 pr. edge- |3 double case  |1-1/4 English|1 ditto     |
  |      |stones.     |large size     |quarter per  |            |
  |      |            |steam kettles. |working hour.|            |
  |Ditto |2 pr. edge- |6 double case  |Not known.   |1 ditto     |
  |      |stones.     |large size     |             |            |
  |      |            |steam kettles. |             |            |
  +------+------------+---------------+-------------+------------+

“_Rape-seed._--I have not turned my attention to quantity of oil
extracted from this seed; but a French crusher (M. Geremboret), on whom
I think one may place considerable dependence, told me, that

  3-1/2 lbs. of best Cambray rape-seed yielded     1 lb. oil.
  3-3/4  --     common rape-seed                   1 lb. oil.
  4-1/4  --       --   poppy-seed                  1 lb. oil.

“Rape-seed weighs from 52 to 56 lbs. per imperial bushel.”

The following are the heads of a reference of machinery for a seed
oil-mill:--

1. Two pairs of cast-iron rollers, 19 inches long, and 10 inches in
diameter, fixed in a cast-iron frame, with brasses, wheels, shafts,
bolts, scrapers, hoppers, shoes, &c.

2. Two pairs of edge-stones, 7 feet diameter each, with two bottom
stones, 6 feet diameter each, cast-iron upright shafts, sweepers,
wheels, shafts, chairs, brasses, bolts, and scrapers, with driving
spur-wheels, &c.

3. Five steam kettles, with wheels, shafts, and brasses, bolts,
breeches, and steam pipes, an upright cast-iron shaft, with chairs and
brasses at each end; and a large bevel wheel upon the bottom end of
upright shaft, and another, smaller, upon fly-wheel shaft, for the first
motions.

4. Five stamper presses, with press plates of cast iron, cast-iron
stamper shaft with 10 arms and 10 rollers, with bosses, brasses, bolts,
driving bevel-wheels.

A well made oil-mill, consisting of the above specified parts, will
manufacture 200 quarters of seed per week.

I have been assured by practical engineers, conversant in oil-mills,
that a double hydraulic press, with 2 ten-inch rams, will do the work of
no more than two of the stamper presses; that is to say, it will work 22
quarters in 24 hours; while three stamper presses will work 33 quarters
in the same time, and produce one half more oil.

_Castor oil, quantity of_,

  +-------+---------+------------+---------+
  |       |         |Retained for|         |
  |       |Imported.|consumption.|Exported.|
  +-------+---------+------------+---------+
  |_Year._| _Cwts._ |  _Cwts._   | _Cwts._ |
  | 1835. |1,109,307|  670,205   | 61,296  |
  | 1836. |  981,585|  809,559   | 68,515  |
  +-------+---------+------------+---------+

Duty, from British possessions, 2_s._ 6_d._ per cwt.; from foreign,
1_s._ per lb.

_Cocoa-nut oil, quantity of,_

  +-------+---------+------------+---------+
  |       |         |Retained for|         |
  |       |Imported.|consumption.|Exported.|
  +-------+---------+------------+---------+
  |_Year._| _Cwts._ |  _Cwts._   | _Cwts._ |
  | 1835. | 19,838  |  14,015    |  2,238  |
  | 1836. | 26,058  |  26,062    |  3,158  |
  | 1837. | 41,218  |  28,836    |         |
  +-------+---------+------------+---------+

_Olive oil, quantity of,_

  +-------+---------+------------+---------+
  |       |         |Retained for|         |
  |       |Imported.|consumption.|Exported.|
  +-------+---------+------------+---------+
  |_Year._|_Galls._ |  _Galls._  | _Galls._|
  | 1835. |  606,166|    554,196 | 283,734 |
  | 1836. |2,682,016|  1,844,622 | 150,561 |
  | 1837. |1,720,397|  1,499,122 |         |
  +-------+---------+------------+---------+

Duties on olive oil, not of Naples and Sicily, 4_d._; of Naples and
Sicily, 8_d._; and, if in ships of these countries, 10_d._ per gallon.

_Train oil, spermaceti, and blubber, quantity of,_

  +-------+---------+------------+---------+
  |       |         |Retained for|         |
  |       |Imported.|consumption.|Exported.|
  +-------+---------+------------+---------+
  |_Year._| _Tuns._ |   _Tuns._  | _Tuns._ |
  | 1835. | 24,197  |   16,114   |  8,035  |
  | 1836. | 19,489  |   18,722   |  1,365  |
  | 1837. | 21,823  |   21,286   |         |
  +-------+---------+------------+---------+

Duties on oil taken by British ships, 1_s._; by foreign fishers, _£_26
18_s._ per tun.


OILS, VOLATILE OR ESSENTIAL; Manufacture of. The volatile oils occur in
every part of odoriferous plants, whose aroma they diffuse by their
exhalation; but in different organs of different species. Certain
plants, such as thyme and the scented _labiatæ_, in general contain
volatile oil in all their parts; but others contain it only in the
blossoms, the seeds, the leaves, the root, or the bark. It sometimes
happens that different parts of the same plant contain different oils;
the orange, for example, furnishes three different oils, one of which
resides in the flowers, another in the leaves, and a third in the skin
or epidermis of the fruit. The quantity of oil varies not only with the
species, but also in the same plant, with the soil, and especially the
climate; thus in hot countries it is generated most profusely. In
several plants, the volatile oil is contained in peculiar orders of
vessels, which confine it so closely that it does not escape in the
drying, nor is dissipated by keeping the plants for many years. In other
species, and particularly in flowers, it is formed continually upon
their surface, and flies off at the moment of its formation.

Volatile oils are usually obtained by distillation. For this purpose the
plant is introduced into a still, water is poured upon it, and heat
being applied, the oil is volatilized by the aid of the watery vapour,
at the temperature of 212°, though when alone it would probably not
distil over unless the heat were 100° more. This curious fact was first
explained in my _New Researches upon Heat_, published in the
Philosophical Transactions for 1818. Most of the essential oils employed
in medicine and perfumery are extracted by distillation from dried
plants; only a few, such as those of the rose and orange flower, are
obtained, from fresh or succulent salted plants. When the mingled
vapours of the oil and water are condensed into the liquid state, by the
refrigerator of the still, the oil separates, and either floats on the
surface or sinks to the bottom of the water. Some oils of a less
volatile nature require a higher heat than 212° to raise them in vapour,
and must be dislodged by adding common salt to the water, whereby the
heat being augmented by 15°, they readily come over. If in such
distillations too much water be added, no oil will be obtained, because
it is partially soluble in water; and thus merely an aromatic water is
produced. If on the other hand too little water be used, the plant may
happen to adhere to the bottom of the still, get partially charred, and
thus impart an empyreumatic odour to the product. But as the quality of
water distilled depends less upon the quantity employed, than upon that
of the surface exposed to the heat, it is obvious that by giving a
suitable form to the still, we may get rid of every inconvenience. Hence
the narrower and taller the alembic is, within certain limits, the
greater will be the proportion of oil relative to that of the aromatic
water, from like proportions of aqueous and vegetable matter employed.
Some place the plants in baskets, and suspend these immediately over the
bottom of the still under the water, or above its surface in the steam.
But the best mode in my opinion is to stuff an upright cylinder full of
the plants, and to drive down through them, steam of any desired force;
its tension and temperature being further regulated by the size of the
outlet orifice leading to the condenser. The cylinder should be made of
strong copper tinned inside, and encased in the worst conducting species
of wood, such as soft deal or sycamore.

The distillation is to be continued as long as the water comes over of a
milky appearance. Certain plants yield so little oil by the ordinary
processes, notwithstanding every care, that nothing but a distilled
water is obtained. In this case, the same water must be poured upon a
fresh quantity of the plants in the still; which being drawn over, is
again to be poured upon fresh plants; and thus repeatedly, till a
certain dose of oil be separated. This being taken off, the saturated
water is reserved for a like distillation.

The refrigeratory vessel is usually a worm or serpentine plunged in a
tub of water, whose temperature should be generally cold; but for
distilling the oils of anise-seed, fennel, &c., which become concrete at
low temperatures, the water should not be cooler than 45° F.

The liquid product is commonly made to run at the worm end, into a
vessel called an Italian or Florentine receiver, which is a conical
matrass, standing on its base, with a pipe rising out of the side close
to the bottom, and recurved a little above the middle of the flask like
the spout of a coffee-pot. The water and the oil collected in this
vessel soon separate from each other, according to their respective
specific gravities; the one floating above the other. If the water be
the denser, it occupies the under portion of the vessel, and continually
overflows by the spout in communication with the bottom, while the
lighter oil is left. When the oil is the heavier of the two, the
receiver should be a large inverted cone, with a stopcock at its apex to
run off the oil from the water when the separation has been completed by
repose. A funnel, having a glass stopcock attached to its narrow stem,
is the most convenient apparatus for freeing the oil finally from any
adhering particles of water. A cotton wick dipped in the oil may also
serve the same purpose by its capillary action. The less the oil is
transvased the better, as a portion of it is lost at every transfer. It
may occasionally be useful to cool the distilled water by surrounding it
with ice, because it thus parts with more of the oil with which it is
impregnated.

There are a few essential oils which may be obtained by expression, from
the substances which contain them; such as the oils of lemons and
bergamot, found in the pellicle of the ripe fruits of the _citrus
aurantium_ and _medica_; or the orange and the citron. The oil comes out
in this case with the juice of the peel, and collects upon its surface.

For collecting the oils of odoriferous flowers which have no peculiar
organs for imprisoning them, and therefore speedily let them exhale,
such as violets, jasmine, tuberose, and hyacinth, another process must
be resorted to. Alternate layers are formed of the fresh flowers, and
thin cotton fleece or woollen cloth-wadding, previously soaked in a pure
and inodorous fat oil. Whenever the flowers have given out all their
volatile oil to the fixed oil upon the fibrous matter, they are replaced
by fresh flowers in succession, till the fat oil has become saturated
with the odorous particles. The cotton or wool wadding being next
submitted to distillation along with water, gives up the volatile oil.
Perfumers alone use these oils; they employ them either mixed as above,
or dissolve them out by means of alcohol. In order to extract the oils
of certain flowers, as for instance of white lilies, infusion in a fat
oil is sufficient.

Essential oils differ much from each other in their physical properties.
Most of them are yellow, others are colourless, red, or brown; some
again are green, and a few are blue. They have a powerful smell, more or
less agreeable, which immediately after their distillation is
occasionally a little rank, but becomes less so by keeping. The odour is
seldom as pleasant as that of the recent plant. Their taste is acrid,
irritating, and heating, or merely aromatic when they are largely
diluted with water or other substances. They are not greasy to the
touch, like the fat oils, but on the contrary make the skin feel rough.
They are almost all lighter than water, only a very few falling to the
bottom of this liquid; their specific gravity lies between 0·847 and
1·096; the first number denoting the density of oil of citron, and the
second that of oil of sassafras. Although styled volatile oils, the
tension of their vapour, as well as its specific heat, is much less than
that of water. The boiling point differs in different kinds, but it is
usually about 316° or 320° Fahr. Their vapours sometimes render reddened
litmus paper blue, although they contain no ammonia. When distilled by
themselves, the volatile oils are partially decomposed; and the gaseous
products of the portion decomposed always carry off a little of the oil.
When they are mixed with clay or sand, and exposed to a distilling heat,
they are in a great measure decomposed; or when they are passed in
vapour through a redhot tube, combustible gases are obtained, and a
brilliant porous charcoal is deposited in the tube. On the other hand,
they distil readily with water, because the aqueous vapour formed at the
surface of the boiling fluid carries along with it the vapour of the oil
produced in virtue of the tension which it possesses at the 212th deg.
Fahr. In the open air, the volatile oils burn with a shining flame,
which deposits a great deal of soot. The congealing point of the
essential oils varies greatly; some do not solidify till cooled below
32°, others at this point, and some are concrete at the ordinary
temperature of the atmosphere. They comport themselves in this respect
like the fat oils; and they probably consist, like them, of two
different oils, a solid and a fluid; to which the names _stearoptène_
and _eleoptène_, or stearessence and oleiessence, may be given. These
may be separated from each other by compressing the cooled concrete oil
between the folds of porous paper; the stearessence remains as a solid
upon the paper; the oleiessence penetrates the paper, and may be
recovered by distilling it along with water.

When exposed to the air, the volatile oils change their colour, become
darker, and gradually absorb oxygen. This absorption commences whenever
they are extracted from the plant containing them; it is at first
considerable, and diminishes in rapidity as it goes on. Light
contributes powerfully to this action, during which the oil disengages a
little carbonic acid, but much less than the oxygen absorbed; no water
is formed. The oil turns gradually thicker, loses its smell, and is
transformed into a resin, which becomes eventually hard. De Saussure
found that oil of lavender, recently distilled, had absorbed in four
winter months, and at a temperature below 54° F., 52 times its volume of
oxygen, and had disengaged twice its volume of carbonic acid gases; nor
was it yet completely saturated with oxygen. The stearessence of
anise-seed oil absorbed at its liquefying temperature, in the space of
two years, 156 times its volume of oxygen gas, and disengaged 26 times
its volume of carbonic acid gas. An oil which has begun to experience
such an oxidizement is composed of a resin dissolved in the unaltered
oil; and the oil may be separated by distilling the solution along with
water. To preserve oils in an unchanged state, they must be put in
phials, filled to the top, closed with ground glass stopples, and placed
in the dark.

Volatile oils are little soluble in water, yet enough so as to impart to
it by agitation their characteristic smell and taste. The water which
distils with any oil is in general a saturated solution of it, and as
such is used in medicine under the name of distilled water. It often
contains other volatile substances contained in the plants, and hence is
apt to putrefy and acquire a nauseous smell when kept in perfectly
corked bottles; but in vessels partially open, these parts exhale, and
the water remains sweet. The waters, however, which are made by
agitating volatile oil with simple distilled water are not apt to spoil
by keeping in well-corked bottles.

The volatile oils are soluble in alcohol, and the more so the stronger
the spirit is. Some volatile oils, devoid of oxygen, such as the oils of
turpentine and citron, are very sparingly soluble in dilute alcohol;
while the oils of lavender, pepper, &c. are considerably so. De Saussure
has inferred from his experiments that the volatile oils are the more
soluble in alcohol, the more oxygen they contain. Such combinations form
the odoriferous spirits which the perfumers incorrectly call waters, as
_lavender water_, _eau de Cologne_, _eau de jasmin_, &c. They become
turbid by admixture of water, which seizes the alcohol, and separates
the volatile oils. Ether also dissolves all the essential oils.

These oils combine with several vegetable acids, such as the acetic, the
oxalic, the succinic, the fat acids (stearic, margaric, oleic), the
camphoric, and suberic.

With the exception of the oil of cloves, the volatile oils do not
combine with the salifiable bases. They have been partially combined
with caustic alkali, as in the case of Starkey’s soap. This is prepared
by triturating recently fused caustic soda in a mortar, with a little
oil of turpentine, added drop by drop, till the mixture has acquired the
consistence of soap. The compound is to be dissolved in spirits of wine,
filtered, and distilled. What remains after the spirit is drawn off,
consists of soda combined with a resin formed in the oil during the act
of trituration.

The volatile oils in general absorb six or eight times their bulk of
ammoniacal gas; but that of lavender absorbs 47 times.

The essential oils dissolve all the fat oils, the resins, and the animal
fats.

In commerce these oils are often adulterated with fat oils, resins, or
balsam of capivi dissolved in volatile oil. This fraud may be detected
by putting a drop of the oil on paper, and exposing it to heat. A pure
essential oil evaporates without leaving any residuum, whilst an oil
mixed with any of the above substances leaves a translucent stain upon
the paper. If fat oil be present, it will remain undissolved, on mixing
the adulterated essential oil with thrice its volume of spirit of wine
of specific gravity 0·840. Resinous matter mixed with volatile oil is
easily detected, being left in the alembic after distillation. Oil
diluted with spirit of wine, forms a milky emulsion on the addition of
water; the alcoholic part is absorbed by the water, and the oil
afterwards found on the surface, in a graduated glass tube will show by
its quantity the amount of the adulteration.

But it is more difficult to detect the presence of a cheap essential oil
in a dear one, which it resembles. Here the taste and smell are our
principal guides. A few drops of the suspected oil are to be poured upon
a bit of cloth, which is to be shaken in the air, and smelled to from
time to time. In this way we may succeed in distinguishing the odour of
the oil which exhales at the beginning, and that which exhales at the
end; a method which serves perfectly to detect oil of turpentine in the
finer essential oils. Moreover, when the debased oil is mixed with
spirits of wine at sp. gr. 0·840, the oil of turpentine remains in a
great measure undissolved. If an oil heavier than water, and an oil
lighter than water, be mixed, they may be separated by agitation for
some time with that liquid, and then leaving the mixture at rest.
Essential oils may also be distinguished by a careful examination of
their respective densities.

_Oil of bitter almonds_, is prepared by exposing the bitter almond cake,
from which the bland oil has been expressed, in a sieve to the vapour of
water rising within the still. The steam, as it passes up through the
bruised almond _parenchyma_, carries off its volatile oil, and condenses
along with it in the worm. The oil which first comes over, and which
falls to the bottom of the water, has so pungent and penetrating a
smell, that it is more like cyanogen gas than hydrocyanic or prussic
acid. This oil has a golden-yellow colour, it is heavier than water;
when much diluted, it has an agreeable smell, and a bitter burning
taste. When exposed to the air, it absorbs oxygen, and lets fall a heap
of crystals of benzoic acid. This oil consists of a mixture of two oils;
one of which is volatile, contains hydrocyanic acid, and is poisonous;
the other is less volatile, is not poisonous, absorbs oxygen, and
becomes benzoic acid. If we dissolve 100 parts of the oil of bitter
almonds in spirit of wine, mix with the solution an alcoholic solution
of potash, and then precipitate the oil with water, we shall obtain a
quantity of cyanide of potash, capable of producing 22-1/2 parts of
prussian blue. Oil of bitter almonds combines with the alkalis.
Perfumers employ a great quantity of this oil in scenting their soaps.
One manufacturer in Paris is said to prepare annually 3 cwt. of this
oil. A similar poisonous oil is obtained by distilling the following
substances with water:--the leaves of the peach (_amygdalus persica_),
the leaves of the bay-laurel (_prunus lauro-cerasus_), the bark of the
plum tree (_prunus padus_), and the bruised kernels of cherry and
plum-stones. All these oils contain hydrocyanic acid, which renders them
poisonous, and they also generate benzoic acid, by absorbing oxygen on
exposure to air.

_Oil of anise-seed_, is extracted by distillation from the seeds of the
_pimpinella anisum_. It is either colourless, or has merely a faint
yellow colour, with the smell and taste of the seed. It concretes in
lamellar crystals at the temperature of 50°, and does not melt again
till heated to 64° nearly. Its specific gravity at 61° is 0·9958, and at
77°, 0·9857. It is soluble in all proportions in alcohol of 0·806; but
only to the extent of 42 per cent. in alcohol of 0·84. When it becomes
resinous by long exposure to the air, it loses its congealing property.
It consists of two oils; a solid stearessence, and a liquid oleiessence,
which may be separated by compression of the cold concrete oil.

_Oil of bergamot_, is extracted by pressure from the rind of the ripe
fruit of the _citrus bergamium_ and _aurantium_. It is a limpid,
yellowish fluid, having a smell resembling that of oranges. Its specific
gravity varies from 0·888 to 0·885. It becomes concrete when cooled a
little below 32°.

_Oil of cajeput_, is prepared in the Moluccas, by distilling the dry
leaves of the _melaleuca leucadendron_. Cajeput is a native word,
signifying merely a white tree. This oil is green; it has a burning
taste, a strong smell of camphor, turpentine, and savine. It is very
fluid, and at 48° has a specific gravity of 0·948. The colour seems to
be derived from the copper vessels in which it is imported, so that it
is removed by distillation with water, which also separates the oil into
two sorts; the first which comes over having a density of 0·897, the
last of 0·920. This has a green colour.

_The oil of caraway_ is extracted from the seeds of the _carum carui_.
It has a pale yellow colour, and the smell and taste of the plant. Its
specific gravity is 0·960. The seeds of the _cuminum cyminum_ (cumin)
afford an oil similar to the preceding, but not so agreeable. Its
specific gravity is 0·975.

_The oil of cassia_, from the _laurus cassia_, is yellow passing into
brown, has a specific gravity of 1·071, and affords a crystalline
stearessence by keeping in a somewhat open vessel.

_The oil of chamomile_ is extracted by distillation from the flowers of
the _matricaria chamomilla_. It has a deep blue colour, is almost
opaque, and thick; and possesses the peculiar smell of the plant. In
the atmosphere it becomes brown and unctuous. If an ounce of oil of
lemons be added to 3 pounds of this oil, they make it separate more
readily from the adhering water.

Other blue oils, having much analogy with oil of chamomile, are obtained
by distilling the following plants: roman chamomile (_anthemis
nobilis_), the flowers of _arnica montana_, and those of milfoil
(_achillæa millefolia_). The last has a spec. grav. of 0·852.

_Oil of cinnamon_, is extracted by distillation from the bark of the
_laurus cinnamomum_. It is produced chiefly in Ceylon, from the pieces
of bark unfit for exportation. It is distilled over with difficulty, and
the process is promoted by the addition of salt water, and the use of a
low still. It has at first a pale yellow colour, but it becomes brown
with age. It possesses in a high degree both the sweet burning taste,
and the agreeable smell of cinnamon. It is heavier than water; its
specific gravity being 1·035. It concretes below 32° F., and does not
fuse again till heated to 41°. It is very sparingly soluble in water,
and when agitated with it readily separates by repose. It dissolves
abundantly in alcohol, and combines with ammonia into a viscid mass, not
decomposed on exposure to air.

When oil of cinnamon is kept for a long time, it deposits a stearessence
in large regular colourless or yellow crystals, which may be pulverized,
and which melt at a very gentle heat into a colourless liquid, which
crystallizes on cooling. It has an odour intermediate between that of
cinnamon and vanilla; and a taste at first greasy, but afterwards
burning and aromatic. It crackles between the teeth. It requires a high
temperature for distillation, and becomes then brown and empyreumatic.
It is very soluble in alcohol.

_The oil of cloves_, is extracted from the dried flower buds of the
_caryophyllus aromaticus_. It is colourless, or yellowish, has a strong
smell of the cloves, and a burning taste. Its specific gravity is 1·061.
It is one of the least volatile oils, and the most difficult to distil.
At the end of a certain time it deposits a crystalline concrete oil. A
similar _stearessence_ is obtained by boiling the bruised cloves in
alcohol, and letting the solution cool. The crystals thus formed are
brilliant, white, grouped in globules, without taste and smell. Oil of
cloves has remarkable chemical properties. It dissolves in alcohol,
ether, and acetic acid. It does not solidify at a temperature of 4°
under 0° F., even when exposed to that cold for several hours. It
absorbs chlorine gas, becomes green, then brown, and turns resinous.
Nitric acid makes it red, and if heated upon it, converts it into oxalic
acid. If mixed by slow degrees with one third of its weight of sulphuric
acid, an acid liquor is formed, at whose bottom a resin of a fine purple
colour is found. After being washed, this resin becomes hard and
brittle. Alcohol dissolves it, and takes a red colour; and water
precipitates it of a blood red hue. It dissolves also in ether. When we
agitate a mixture of strong caustic soda lye and oil of cloves in equal
parts, the mass thickens very soon, and forms delicate lamellar
crystals. If we then pour water upon it, and distil, there passes along
with the water, a small quantity of an oil which differs from oil of
cloves both in taste and chemical properties. During the cooling, the
liquor left in the retort lets fall a quantity of crystalline needles,
which being separated by expression from the alkaline liquid, are almost
inodorous, but possess an alkaline taste, joined to the burning taste of
the oil. These crystals require for solution from 10 to 12 parts of cold
water. Potash lye produces similar effects. Ammoniacal gas transmitted
through the oil is absorbed and makes it thick. The concrete combination
thus formed remains solid as long as the phial containing it is corked,
but when opened, the compound becomes liquid; and these phenomena may be
reproduced as many times as we please. Such combinations are decomposed
by acids, and the oil set at liberty has the same taste and smell as at
first, but it has a deep red colour. The alkalis enable us to detect the
presence of other oils, as that of turpentine or sassafras, in that of
cloves, because they fix the latter, while the former may be volatilized
with water by distilling the mixture. The oil of cloves found in
commerce is not pure, but contains a mixture of the tincture of pinks or
clove-gilly flowers, whose acrid resin is thereby introduced. It is
sometimes sophisticated with other oils.

_The oil of elder_, is extracted by distillation from the flowers of the
_sambucus nigra_. It has the consistence of butter. The watery solution
is used in medicine.

_Oil of fennel_, is extracted by distillation from the seeds of the
_anethum fœniculum_. It is either colourless or of a yellow tint, has
the smell of the plant, and a specific gravity of 0·997. When treated
with nitric acid, it affords benzoin. It congeals at the temperature of
14° F., and then yields by pressure a solid and a liquid oil; the former
appearing in crystalline plates. It is used in this country for scenting
soap.

_Oils of fermented liquors._ The substances usually fermented contain a
small quantity of essential oils, which become volatile along with the
alcoholic vapours in distillation, and progressively increase as the
spirits become weaker towards the end of the process. The vapours then
condense into a milky liquor. These oils adhere strongly to the alcohol,
and give it a peculiar acrid taste. They differ according to the vinous
wash from which they are obtained, and combine with greater or less
facility with caustic alkalis.

1. _Oil of grain spirits._ At the ordinary temperature it is partially a
white solid; when cooled lower it assumes the aspect of suet, and
therefore consists chiefly of stearessence. Its taste and smell are most
offensive; it swims upon the surface of water, and even of spirit
containing 30 per cent. of alcohol. It sometimes derives a green colour
from the copper worm of the still. When heated it fuses and turns
yellow. When it has become resinous by the agency of the atmosphere, it
gives a greasy stain to paper. It dissolves in 6 parts of anhydrous
alcohol, and in 2 of ether; and is said to crystallize when the spirit
solution has been saturated with it hot, and is allowed to cool. By
exposure to a freezing mixture, the whiskey which contains it lets it
fall. Caustic potash dissolves it very slowly, and forms a soap soluble
in 60 parts of water. It is absorbed by wood charcoal, and still better
by bone black; whereby it may be completely abstracted from bad whiskey.
According to Buchner, another oil may also be obtained from the residuum
of the second distillation of whiskey, if saturated with sea salt, and
again distilled. Thus we obtain a pale yellow fluid oil, which does not
concrete with cold, possessed of a disagreeable smell and acrid taste.
Its specific gravity is 0·835. It is soluble in alcohol and ether.

2. _The oil from potato spirits_, has properties quite different from
the preceding. It is obtained in considerable quantity by continuing the
distillation after most of the alcohol has come over, and it appears in
the form of a yellowish oil, mixed with water and spirits. After being
agitated first with water, then with a strong solution of muriate of
lime, and distilled afresh, it possesses the following properties: it is
colourless, limpid, has a peculiar smell, and a bitter hot taste of
considerable permanence. It leaves no greasy stain upon paper, remains
liquid at 0° F., but cooled below that point it crystallizes like oil of
anise-seed. When pure it boils at 257° F.; but at a lower degree, if it
contains alcohol. Its specific gravity is 0·821, or 0·823 when it
contains a little water. It burns with a clear flame without smoke, but
it easily goes out, if not burned with a wick. It dissolves in small
quantity in water, to which it imparts its taste and the properties of
forming a lather by agitation. It dissolves in all proportions in
alcohol. Chlorine renders it green. Concentrated sulphuric acid converts
it into a crimson solution, from which it is precipitated yellow by
water. It dissolves in all proportions in acetic acid. Concentrated
caustic lyes dissolve it, but give it up to water. It does not appear to
be poisonous, like the oil of corn spirits; because, when given by
spoonfuls to dogs, it produced no other effect but vomiting.

3. _The oil of brandy or grape spirits_, is obtained during the
distillation of the fermented residuum of expressed grapes; being
produced immediately after the spirituous liquor has passed over. It is
very fluid, limpid, of a penetrating odour, and an acrid disagreeable
taste. It grows soon yellow in the air. When this oil is distilled, the
first portions of it pass unchanged, but afterwards it is decomposed and
becomes empyreumatic. It dissolves in 1000 parts of water, and
communicates to it its peculiar taste and smell. One drop of it is
capable of giving a disagreeable flavour to ten old English gallons of
spirits. It combines with the caustic alkalis, and dissolves sulphur.

_Oil of Juniper_, is obtained by distilling juniper berries along with
water. These should be bruised, because their oil is contained in small
sacs or reservoirs, which must be laid open before the oil can escape.
It is limpid and colourless, or sometimes of a faint greenish yellow
colour. Its specific gravity is 0·911. It has the smell and taste of the
juniper. Water, or even alcohol, dissolves very little of it. Gin
contains a very minute quantity of this oil. Like oil of turpentine, it
imparts to the urine of persons who swallow it, the smell of violets.
Oil of juniper is frequently sophisticated with oil of turpentine
introduced into the still with the berries; a fraud easily detected by
the diminished density of the mixture.

_The oil of lavender_, is extracted from the flowering spike of the
_lavandula spica_. It is yellow, very fluid, has a strong odour of the
lavender, and a burning taste. The specific gravity of the oil found in
commerce is 0·898 at the temperature of 72° F., and of 0·877 when it has
been rectified. It is soluble in all proportions in alcohol of 0·830,
but alcohol of 0·887 dissolves only 42 per cent. of its weight. The
fresh oil detonates slightly when mixed with iodine, with the production
of a yellow cloud. There occurs in commerce a kind of oil of lavender
known under the name of oil of _aspic_ or oil of _spike_, extracted by
distillation from a wild variety of the _lavandula spica_, which has
large leaves, and is therefore called _latifolia_. This oil is
manufactured in the south of Europe. Its odour is less characteristic
than that of the lavender, resembling somewhat that of oil of
turpentine, with which it is indeed often adulterated. It is also so
cheap as to be sometimes used instead of the latter oil. Oil of lavender
deposits, when partially exposed to the air, a concrete oil, which
resembles camphor, to the amount of one fourth of its weight.

_Oil of lemons_, is extracted by pressure from the yellow peel of the
fruit of the lemon, or _citrus medica_. In this state it is a yellowish
fluid, having a specific gravity of 0·8517; but when distilled along
with water till three fifths of the oil have come over, it is obtained
in a colourless state, and of a specific gravity of 0·847 at 72° F. This
oil does not become concrete till cooled to 4° below 0° F.

The oil of lemons has a very agreeable smell of the fruit, which is
injured by distillation. It is soluble in all proportions in anhydrous
alcohol, but only 14 parts dissolve in 100 of spirits of wine of
specific gravity 0·837. This oil, especially when distilled, forms with
muriatic acid similar camphorated compounds with oil of turpentine,
absorbing no less than 280 volumes of the acid gas.

Oil of lemons kept long, in ill-corked bottles, generates a quantity of
stearessence, which when dissolved in alcohol, precipitated by water,
and evaporated, affords brilliant, colourless, transparent needles. Some
acetic acid is also generated in the old oil. According to Brandes, the
specific gravity of oil of lemons is 0·8786.

_The oil of mace_, lets fall, after a certain time, a concrete oil under
the form of a crystalline crust, called by John _myristicine_.

_The oil of nutmegs_, is extracted chiefly from mace, which is the inner
epidermis of these nuts. It is colourless, or yellowish, a little viscid
with a strong aromatic odour of nutmegs, an acrid taste, and a specific
gravity of 0·948. It consists of two oils, which may be easily separated
from each other by agitation with water; for one of them, which is more
volatile and aromatic comes to the surface, while the other, which is
denser, white, and of a buttery consistence, falls to the bottom. The
latter liquefies by the heat of the hand.

_The oil of orange flowers_, called _neroli_, is extracted from the
fresh flowers of the _citrus aurantium_. When recently prepared it is
yellow; but when exposed for two hours to the rays of the sun, or for a
longer time to diffuse daylight, it becomes of a yellowish-red. It is
very fluid, lighter than water, and has a most agreeable smell. The
aqueous solution known under the name of orange-flower water, is used as
a perfume. It is obtained either by dissolving the oil in water, or by
distilling with water the leaves either fresh or salted; the first being
the stronger, but the last being the more fragrant preparation.
Orange-flower water obtained by distillation, contains besides the oil,
a principle which comes over with it, of a nature hitherto unknown; it
possesses the property of imparting to water the faculty of becoming red
with a few drops of sulphuric acid. The water formed from the oil alone,
is destitute of this property. The intensity of the rose-colour is a
test in some measure of the richness of the water in oil.

_The oil of parsley_, is extracted from the _apium petroselinum_. It is
of a pale yellow colour, having the smell of the plant, and consists of
two oils separable by agitation in water. Its liquid part floats upon
the surface in a very fluid form; its stearessence, which falls to the
bottom, is butyraceous and crystallizes at a low temperature. This
concrete oil melts at 86° F.

_The oil of pepper_, is extracted from the _piper nigrum_. In the recent
state it is limpid and colourless, but by keeping it becomes yellow. It
swims upon the surface of water. In odour it resembles pepper, but is
devoid of its hot taste.

_The oil of peppermint_ is extracted from the _mentha piperita_. It is
yellowish, and endued with a very acrid burning taste. Its specific
gravity is 0·920. At 6° or 7° below 0° F., it deposits small capillary
crystals. After long keeping it affords a stearessence resembling
camphor, provided the oil had been obtained from the dry plant gathered
in flower, but not from distillation of the fresh plant. When
artificially cooled, it yields 6 per cent. of stearessence, which
crystallizes in prisms with three sides, has an acrid somewhat rank
taste, is soluble in ether and alcohol, and is thrown down from the
latter solution by water in the form of a white powder. Peppermint water
is characterized by the sensation of coolness which it diffuses in the
mouth.

_The oil of pimento_, is extracted from the envelopes of the fruits of
the _myrtus pimenta_, which afford 8 per cent. of it. It is yellowish,
almost colourless, of a smell analogous to that of cloves, an acrid
burning taste, and a specific gravity greater than water. Nitric acid
makes it first red, and after the effervescence, of a rusty brown hue.
It combines with the salifiable bases, like oil of cloves.

_The oil of rhodium_, is extracted from the wood of the _convolvolus
scoparius_. It is very fluid, and has a yellow colour, which in time
becomes red. It has somewhat of the rose odour, and is used to
adulterate the genuine _otto_. Its taste is bitter and aromatic, which
it imparts to the otto as well as its fluidity.

_The oil of roses_, called also the _attar_ or _otto_, is extracted by
distillation from the petals of the _rosa centifolia_ and
_sempervirens_. Our native roses furnish such small quantities of the
oil, that they are not worth distilling for the purpose. The best way of
operating is to return the distilled water repeatedly upon fresh petals,
and eventually to cool the saturated water with ice; whereby a little
butyraceous oil is deposited. But the oil thus obtained has not a very
agreeable odour, being injured by the action of the air in the repeated
distillations. In the East Indies, the attar is obtained by stratifying
rose leaves in earthen pans in alternate layers, with the oleiferous
seeds of a species of digitalis, called _gengeli_, for several days, in
a cool situation. The fat oil of the seed absorbs the essential oil of
the rose. By repeating this process with fresh leaves and the same seed,
this becomes eventually swollen, and being then expressed furnishes the
oil. The turbid liquid thus obtained is left at rest, in well-closed
vessels, where it gets clarified. The layer of oil that floats on the
top is then drawn off by a capillary cotton wick, and subjected to
distillation along with water, whereby the volatile otto is separated
from the fat seed-oil.

The oil of roses is colourless, and possesses the smell of roses, which
is not however agreeable, unless when diffused, for in its concentrated
state it is far from pleasant to the nostrils, and is apt to occasion
headaches. Its taste is bland and sweetish. It is lighter than water,
and at the temperature of 92°, its specific gravity compared to that of
water at 60° is 0·832. At lower temperatures it becomes concrete and
butyraceous; and afterwards fuses at 90°. It is but slightly soluble in
alcohol; 1000 parts of this liquid at 0·806 dissolving only 7-1/2 parts
at 58° F. This oil consists of two parts, the stearessence and
oleiessence; the latter being the more volatile odoriferous portion.

_The oil of rosemary_, is extracted from the _rosmarinus officinalis_.
It is as limpid as water, has the smell of the plant, and in other
respects resembles oil of turpentine. The oil found in commerce has a
specific gravity of 0·911, which becomes 0·8886 by rectification. It
boils at 320° F. (occasionally at 329°). It is soluble in all portions
in alcohol of 0·830. When kept in imperfectly closed vessels, it
deposits a stearessence to the amount of one tenth of its weight,
resembling camphor. It is sometimes adulterated with oil of turpentine,
a fraud easily detected by adding anhydrous alcohol, which dissolves
only the oil of rosemary.

_The oil of saffron_, is extracted from the _stigmata_ of the _crocus
sativus_. It is yellow, very fluid, falls to the bottom of water,
diffuses the penetrating odour of the plant, and has an acrid and bitter
taste. It is narcotic.

_The oil of sassafras_, is extracted from the woody root of the _laurus
sassafras_. It is colourless; but at the end of a certain time it
becomes yellow or red. It has a peculiar, sweetish, pretty agreeable,
but somewhat burning taste. Its specific gravity is 1·094. According to
Bonastre, this oil separates by agitation with water into an oil lighter
and an oil heavier than this fluid. When long kept, it deposits a
stearessence in transparent and colourless crystals, which have the
smell and taste of the liquid oil.

_The oil of savine_, is extracted from the leaves of the _juniperus
sabina_. It is limpid, and has the odour and taste of the plant, which
is one more productive of volatile oil than any other.

_The oil of tansy_ has a specific gravity of 0·946, the penetrating
odour of the _tanacetum vulgare_, with an acrid and bitter taste.

_Oil of turpentine_, commonly called essence of turpentine. It is
extracted from several species of turpentine, a semi-liquid resinous
substance which exudes from certain trees of the _pine_ tribe, and is
obtained by distilling the resin along with water. This oil is the
cheapest of all the volatile species, and, as commonly sold, contains a
little resin, from which it may be freed by re-distillation with water.
It is colourless, limpid, very fluid, and has a very peculiar smell. Its
specific gravity at 60° is 0·872; that of the spirit on sale in the
shops is 0·876. This oil always reddens litmus paper, because it
contains a little succinic acid.

100 parts of spirits of wine, of specific gravity 0·84, dissolve only
13-1/2 of oil of turpentine at 72° F. When agitated with alcohol at
0·830 the oil retains afterwards one fifth of its bulk of the spirit;
hence this proposed method for purifying oil of turpentine is defective.
The oil if left during four months in contact with air is capable of
absorbing 20 times its bulk of oxygen gas. One volume of rectified oil
of turpentine absorbs at the temperature of 72°, and under the common
atmospheric pressure, 163 times its volume of muriatic acid gas,
provided the vessel be kept cool with ice. This mixture being allowed to
repose for 24 hours, produces out of the oil from 26 to 47 per cent. of
a white crystalline substance, which subsides to the bottom of a brown,
smoking, translucent liquor. Others say that 100 parts of oil of
turpentine yield 110 of this crystalline matter, which was called by
Kind, its discoverer, artificial camphor, from its resemblance in smell
and appearance to this substance. Both the solid and the liquid are
combinations of muriatic acid and oil of turpentine; indicating the
existence of a stearine and an oleine in the latter substance. The
liquid compound is lighter than water, and is not decomposed by it, nor
does it furnish any more solid matter when more muriatic gas is passed
through it. The solid compound, after being washed first with water
containing a little carbonate of soda, then with pure water, and finally
purified by sublimation with some chalk, lime, ashes, or charcoal,
appears as a white, translucent, crystalline body, in the form of
flexible, tenacious needles. It swims upon the surface of water,
diffuses a faint smell of camphor, commonly mixed with that of oil of
turpentine, and has rather an aromatic than a camphorated taste. It does
not redden litmus paper. Water dissolves a very minute quantity; but
cold alcohol of 0·806 dissolves fully one third of its weight, and hot
much more, depositing, as it cools, this excess in the form of crystals.
The solution is not precipitated by nitrate of silver, which shows that
the nature of the muriatic acid is perfectly masked by the combination.
It is composed, in 100 parts, of 76·4 carbon, 9·6 hydrogen, and 14
muriatic acid. The muriatic acid, or chlorine may be separated by
distilling an alcoholic solution of the artificial camphor 12 or 14
times in succession with slaked lime.

Oil of turpentine is best preserved in casks enclosed within others,
with water between the two. Its principal use is for making varnishes,
and as a remedy for the tape-worm.

_The oil of thyme_, is extracted from the _thymus serpyllum_. It is
reddish yellow, has an agreeable smell, and, after being long kept, it
lets fall a crystalline stearessence. It is used merely as a perfume.

_The oil of wormwood_, is extracted from the _artemisia absinthium_. It
is yellow, or sometimes green, and possesses the odour of the plant. Its
taste resembles that of wormwood, but without its bitterness. Its
specific gravity is 0·9703 according to Brisson and 0·9725 according to
Brandes. It detonates with iodine when it is fresh. Treated with nitric
acid of 1·25 specific gravity, it becomes first blue, and after some
time brown.


OIL OF VITRIOL, is the old name of concentrated SULPHURIC ACID.


OLEATES, are saline compounds of oleic acid with the bases.


OLEFIANT GAS, is the name originally given to bi-carburetted hydrogen.


OLEIC ACID, is the acid produced by saponifying olive-oil, and then
separating the base by dilute sulphuric or muriatic acid. See FATS, and
STEARINE.


OLEINE, is the thin oily part of fats, naturally associated in them with
glycerine, margarine, and stearine.


OLIBANUM, is a gum-resin, used only as incense in Roman-catholic
churches.


OLIVE OIL. See OILS, UNCTUOUS.


ONYX, an ornamental stone of little value; a subspecies of quartz.


OOLITE, is a species of limestone composed of globules clustered
together, commonly without any visible cement or base. These vary in
size from that of small pin-heads to peas; they sometimes occur in
concentric layers, at others they are compact, or radiated from the
centre to the circumference; in which case, the oolite is called
_roogenstein_ by the German mineralogists. In geology the oolitic series
includes all the strata between the iron sand above and the red marl
below. It is the great repository of the best architectural materials
which the midland and eastern parts of England produce; it is divided
into three systems:--

1. _The upper oolite_, including the argillo-calcareous Purbeck strata,
which separate the iron and oolitic series; the oolitic strata of
Portland, Tisbury, and Aylesbury; the calcareous sand and concretions,
as of Shotover and Thame; and the argillo-calcareous formation of
Kimmeridge, the oak tree of Smith.

2. _The middle oolite_; the oolitic strata associated with the coral
rag; calcareous sand and grit; great Oxford clay, between the oolites of
this and the following system.

3. _The lower oolite_; which contains numerous oolitic strata,
occasionally subdivided by thin argillaceous beds; including the
cornbrash, forest marble, schistose oolite, and sand of Stonesfield and
Hinton, great oolite and inferior oolite; calcareo-siliceous sand
passing into the inferior oolite; great argillo-calcareous formation of
lias, and lias marl, constituting the base of the whole series.

These formations occupy a zone 30 miles broad in England.


OOST, or OAST; the trivial or provincial name of the stove in which the
picked hops are dried.


OPAL; an ornamental stone of moderate value. See LAPIDARY.


OPERAMETER, is the name given to an apparatus patented in February,
1829, by Samuel Walker, cloth manufacturer, in the parish of Leeds. It
consists of a train of toothed wheels and pinions enclosed in a box,
having indexes attached to the central arbor, like the hands of a clock,
and a dial plate; whereby the number of rotations of a shaft projecting
from the posterior part of the box is shown. If this shaft be connected
by any convenient means to the working parts of a gig mill, shearing
frame, or any other machinery of that kind for dressing cloths, the
number of rotations made by the operating machine will be exhibited by
the indexes upon the dial plate of this apparatus. In dressing cloths,
it is often found that too little or too much work has been expended
upon them, in consequence of the unskilfulness or inattention of the
workmen. By the use of the operameter, that evil will be avoided, as the
master may regulate and prescribe beforehand by the dial the number of
turns which the wheels should perform.

A similar clock-work mechanism, called a _counter_, has been for a great
many years employed in the cotton factories to indicate the number of
revolutions of the main shaft of the mill, and of course the quantity of
yarn that might or should be spun, or of cloth that might be woven in
the power looms. A common pendulum or spring clock is commonly set up
alongside of the counter; and sometimes the indexes of both are
regulated to go together, when the mill performs its average work.


OPIUM, is the juice which exudes from incisions made in the heads of
ripe poppies, (_papaver somniferum,_) rendered concrete by exposure to
the air and the sun. The best opium which is found in the European
markets comes from Asia Minor and Egypt; what is imported from India is
reckoned inferior in quality. This is the most valuable of all the
vegetable products of the gum-resin family: and very remarkable for the
complexity of its chemical composition. Though examined by many able
analysts, it still requires further elucidation.

Opium occurs in brown lumps of a rounded form, about the size of the
fist, and often larger; having their surface covered with the seeds and
leaves of a species of _rumex_, for the purpose of preventing the mutual
adhesion of the pieces in their semi-indurated state. These seeds are
sometimes introduced into the interior of the masses to increase their
weight; a fraud easily detected by cutting them across. Good opium is
hard in the cold, but becomes flexible and doughy when it is worked
between the hot hands. It has a characteristic smell, which by heat
becomes stronger, and very offensive to the nostrils of many persons. It
has a very bitter taste. Water first softens, and then reduces it to a
pasty magma. Proof spirit digested upon opium forms _laudanum_, being a
better solution of its active parts than can be obtained by either water
or strong alcohol alone. Water distilled from it acquires its peculiar
smell, but carries over no volatile oil.

Opium was analyzed by Bucholz and Braconnot, but at a period anterior to
the knowledge of the alkaline properties of morphia and opian
(narcotine). Bucholz found in 100 parts of it, 9·0 of resin; 30·4 of
gum; 35·6 of extractive matter; 4·8 of caoutchouc; 11·4 of gluten; 2·0
of ligneous matter, as seeds, leaves, &c.; 6·8 of water and loss. John,
who made his analysis more recently, obtained 2·0 parts of a rancid
nauseous fat; 12·0 of a brown hard resin; 10·0 of a soft resin; 2 of an
elastic substance; 12·0 of morphia and opian; 1·0 of a balsamic extract;
25·0 of extractive matter; 2·5 of the meconates of lime and magnesia;
18·5 of the epidermis of the heads of the poppy; 15 of water, salts, and
odorous matter.

In the Numbers of the Quarterly Journal of Science for January and June,
1830, I published two papers upon opium and its tests, containing the
results of researches made upon some porter which had been fatally dosed
with that drug; for which crime, a man and his wife had been capitally
punished, about a year before, in Scotland.[36] From the first of these
papers the following extract is made:--

  [36] A country merchant travelling in a steam-boat upon the river
  Clyde, who had incautiously displayed a good deal of money, was
  poisoned with porter charged with laudanum. The contents of the dead
  man’s stomach were sent to me for analysis.

“Did the anodyne and soporific virtue of opium reside in one definite
principle, chemical analysis might furnish a certain criterion of its
powers. It has been pretty generally supposed that this desideratum is
supplied by Sertürner’s discovery of morphia. Of this narcotic alkali
not more than 7 parts can be extracted by the most rigid analysis from
100 of the best Turkey opium; a quantity, indeed, somewhat above the
average result of many skilful chemists. Were morphia the real medicinal
essence of the poppy, it should display, when administered in its active
saline state of acetate, an operation on the living system commensurate
in energy with the fourteen-fold concentration which the opium has
undergone. But so far as may be judged from the most authentic recent
trials, morphia in the acetate seems to be little, if any, stronger as a
narcotic than the heterogeneous drug from which it has been eliminated.
Mr. John Murray’s experiments would, in fact, prove it to be greatly
weaker; for he gave 2 drachms of superacetate of morphia to a cat,
without causing any poisonous disorder. This is perhaps an extreme case,
and may seem to indicate either some defect in the preparation, or an
uncommon tenacity of life in the animal. To the same effect Lassaigne
found that a dog lived 12 hours after 36 grains of acetate of morphia in
watery solution had been injected into its jugular vein. The morphia
meanwhile was entirely decomposed by the vital forces, for none of it
could be detected in the blood drawn from the animal at the end of that
period. Now, from the effects produced by 5 grains of watery extract of
opium, injected by Orfila into the veins of a dog, we may conclude that
a quantity of it, equivalent to the above dose of the acetate of
morphia, would have proved speedily fatal.

“Neither can we ascribe the energy of opium to the white crystalline
substance called _narcotine_, or _opian_, extracted from it by the
solvent agency of sulphuric ether; for Orfila assures us that these
crystals may be swallowed in various forms by man, even to the amount of
2 drachms in the course of 12 hours, with impunity; and that a drachm of
it dissolved in muriatic or nitric acid may be administered in the food
of a dog without producing any inconvenience to the animal. It appears,
however, on the same authority, that 30 grains of it dissolved in
acetic or sulphuric acid caused dogs that had swallowed the dose to die
under convulsions in the space of 24 hours, while the head was thrown
backwards on the spine. Oil seems to be the most potent menstruum of
narcotine; for 3 grains dissolved in oil readily kill a dog, whether the
dose be introduced into the stomach or into the jugular vein.

“Since a bland oil thus seems to develop the peculiar force of
narcotine, and since opium affords to ether, and also to ammonia, an
unctuous or fatty matter, and a resin (the caoutchouc of Bucholz) to
absolute alcohol, we are entitled to infer that the activity of opium is
due to its state of composition, to the union of an oleate or margarate
of narcotine with morphia. The meconic acid associated with this
salifiable base has no narcotic power by itself, but may probably
promote the activity of the morphia.”

Opian or narcotine, and morphia, may be well prepared by the following
process. The watery infusion of opium being evaporated to the
consistence of an extract, every 3 parts are to be diluted with one and
a half parts in bulk of water, and then mixed in a retort with 20 parts
of ether. As soon as 5 parts of the ether have been distilled over, the
narcotic salt contained in the extract will be dissolved. The fluid
contents of the retort are to be poured hot into a vessel apart, and the
residuum being washed with 5 other parts of ether, they are to be added
to the former. Crystals of narcotine will be obtained as the solution
cools. The remaining extract is to be diluted in the retort with a
little water, and the mixture set aside in a cool place. After some
time, some narcotine will be found crystallized at the bottom. The
supernatant liquid thus freed from narcotine being decanted off, is to
be treated with caustic ammonia; and the precipitate thrown upon a
filter. This, when well washed and dried, is to be boiled with a
quantity of spirit of wine at 0·84, equal to thrice the weight of the
opium employed, containing 6 parts of animal charcoal for every hundred
parts of the drug. The alcoholic solution being filtered hot, affords,
on cooling, colourless crystals of morphia.

This alkali may be obtained by a more direct process, without alcohol or
ether. A solution of opium in vinegar, is to be precipitated by ammonia;
the washed precipitate is to be dissolved in dilute muriatic acid, the
solution is to be boiled along with powdered bone black, filtered, and
then precipitated by ammonia. This, when washed upon a filter and dried,
is white morphia, which may be dissolved in hot alcohol, if fine
crystals be wanted. See MORPHIA.

_Opium, quantity of,_

  +-------+---------+------------+---------+
  |       |Imported.|Retained for|Exported.|
  |       |         |consumption.|         |
  +-------+---------+------------+---------+
  |_Year._| _Libs._ |  _Libs._   | _Libs._ |
  |1885.  |  85,481 |   31,181   |  74,126 |
  |1836.  | 130,794 |   38,943   |  70,824 |
  +-------+---------+------------+---------+

Duty, at present, 1_s._ per lb.


OPOBALSAM, is the balsam of Peru in a dry state.


OPOPONAX, is a gum-resin resembling gum ammoniac. It is occasionally
used in medicine.


ORANGE DYE, is given by a mixture of red and yellow dyes in various
proportions. Annotto alone dyes orange; but it is a fugitive colour.


ORCINE, is the name of the colouring principle of the _lichen
dealbatus_. The lichen dried and pulverized is to be exhausted by
boiling alcohol. The solution filtered hot, lets fall in the cooling,
crystalline flocks, which do not belong to the colouring matter. The
supernatant alcohol is to be distilled off, the residuum is to be
evaporated to the consistence of an extract, and triturated with water
till this liquid will dissolve no more. The aqueous solution reduced to
the consistence of syrup, and left to itself in a cool place, lets fall,
at the end of a few days, long brown brittle needles, which are to be
freed by pressure from the mother water, and dried. That water being
treated with animal charcoal, filtered and evaporated, will yield a
second crop of crystals. These are orcine. Its taste is sweet and
nauseous; it melts readily in a retort into a transparent liquid, and
distils without undergoing any change. It is soluble in water and
alcohol. Nitric acid colours it blood-red; which colour afterwards
disappears. Subacetate of lead precipitates it completely. Its
conversion into the archil red is effected by the action of an alkali,
in contact with the air. When dissolved, for example, in ammonia, and
exposed to the atmosphere, it takes a dirty brown red hue; but when the
orcine is exposed to air charged with vapours of ammonia, it assumes by
degrees a fine violet colour. To obtain this result, the orcine in
powder should be placed in a capsule, alongside of a saucer containing
water of ammonia; and both should be covered by a large bell glass;
whenever the orcine has acquired a dark brown cast, it must be
withdrawn from under the bell, and the excess of ammonia be allowed to
volatilize. As soon as the smell of ammonia is gone, the orcine is to be
dissolved in water; and then a few drops of ammonia being poured into
the brownish liquid, it assumes a magnificent reddish-violet colour.
Acetic acid precipitates the red lake of lichen.


ORES (_Mines_, Fr.; _Erze_, Germ.); are the mineral bodies which contain
so much metal as to be worth the smelting, or being reduced by fire to
the metallic state. The substances naturally combined with metals, which
mask their metallic characters, are chiefly oxygen, chlorine, sulphur,
phosphorus, selenium, arsenic, water, and several acids, of which the
carbonic is the most common. Some metals, as gold, silver, platinum,
often occur in the metallic state, either alone, or combined with other
metals, constituting what are called native alloys.

I have described in the article MINE, the general structure of the great
metallic repositories within the earth, as well as the most approved
methods of bringing them to the surface; and in the article METALLURGY,
the various mechanical and chemical operations requisite to reduce the
ores into pure metals. Under each particular metal, moreover, in its
alphabetical place, will be found a systematic account of its most
important ores.

Relatively to the theory of the smelting of ores, the following
observations may be made. It is probable that the coaly matter employed
in that process is not the _immediate_ agent of their reduction; but the
charcoal seems first of all to be transformed by the atmospherical
oxygen into the oxide of carbon; which gaseous product then surrounds
and penetrates the interior substance of the oxides, with the effect of
decomposing them, and carrying off their oxygen. That this is the true
mode of action, is evident from the well-known facts, that bars of iron,
stratified with pounded charcoal, in the steel cementation-chest, most
readily absorb the carbonaceous principle to their innermost centre,
while their surfaces get blistered by the expansion of carburetted gases
formed within; and that an intermixture of ores and charcoal is not
always necessary to reduction, but merely an interstratification of the
two, without intimate contact of the particles. In this case, the
carbonic acid which is generated at the lower surfaces of contact of the
strata, rising up through the first bed of ignited charcoal, becomes
converted into carbonic oxide; and this gaseous matter, passing up
through the next layer of ore, seizes its oxygen, reduces it to metal,
and is itself thereby transformed once more into carbonic acid; and so
on in continual alternation. It may be laid down, however, as a general
rule, that the reduction is the more rapid and complete, the more
intimate the mixture of the charcoal and the metallic oxide has been,
because the formation of both the carbonic acid and carbonic oxide
becomes thereby more easy and direct. Indeed the cementation of iron
bars, into steel will not succeed, unless the charcoal be so porous as
to contain, interspersed, enough of air to favour the commencement of
its conversion into the gaseous oxide; thus acting like a ferment in
brewing. Hence also finely pulverized charcoal does not answer well;
unless a quantity of ground iron cinder or oxide of manganese be blended
with it, to afford enough of oxygen to begin the generation of carbonic
oxide gas; whereby the successive transformations into acid, and oxide,
are put in train.


ORPIMENT (Eng. and Fr., _Yellow sulphuret of arsenic_; _Operment_,
_Rauschgelb_, Germ.); occurs in indistinct crystalline particles, and
sometimes in oblique rhomboidal prisms; but for the most part, in kidney
and other imitative forms; it has a scaly and granular aspect; texture
foliated, or radiated; fracture small granular, passing into conchoidal;
splintery, opaque, shining, with a weak diamond lustre; lemon, orange,
or honey yellow; sometimes green; specific gravity, 3·44 to 3·6. It is
found in floetz rocks, in marl, clay sand-stone, along with realgar,
lead-glance, pyrites, and blende, in many parts of the world. It
volatilizes at the blowpipe. It is used as a pigment.

The finest specimens come from Persia, in brilliant yellow masses, of a
lamellar texture, called golden orpiment.

Artificial orpiment is manufactured chiefly in Saxony, by subliming in
cast-iron cucurbits, surmounted by conical cast-iron capitals, a mixture
in due proportions of sulphur and arsenious acid (white arsenic). As
thus obtained, it is in yellow compact opaque masses, of a glassy
aspect; affording a powder of a pale yellow colour. Genuine orpiment is
often adulterated with an ill-made compound; which is sold in this
country by the preposterous name of king’s yellow. This fictitious
substance is frequently nothing else than white arsenic combined with a
little sulphur; and is quite soluble in water. It is therefore a deadly
poison, and has been administered with criminal intentions and fatal
effects. I had occasion, some years ago, to examine such a specimen of
king’s yellow, with which a woman had killed her child. A proper
insoluble sulphuret of arsenic, like the native or the Saxon, may be
prepared by transmitting sulphuretted hydrogen gas through any arsenical
solution. It consists of 38·09 sulphur, and 60·92 of metallic arsenic,
and is not remarkably poisonous. The finest kinds of native orpiment
are reserved for artists; the inferior are used for the indigo vat. They
are all soluble in alkaline lyes, and in water of ammonia.


ORYCTNOGNOSY, is the name given by Werner to the knowledge of minerals;
and is therefore synonymous with the English term Mineralogy.


OSTEOCOLLA, is the glue obtained from bones, by removing the earthy
phosphates with muriatic acid, and dissolving the cartilaginous residuum
in water at a temperature considerably above the boiling point, by means
of a digester. It is a very indifferent article.


OSMIUM, is a metal discovered by Mr. Tennant in 1803, among the grains
of native platinum. It occurs also associated with the ore of iridium.
As it has not been applied to any use in the arts, I shall reserve any
chemical observations that the subject may require for the article
PLATINUM.


OXALATES, are saline compounds of the bases with


OXALIC ACID (_Acide oxalique_, Fr.; _Sauerkleesaüre_, Germ.); which is
the object of a considerable chemical manufacture. It is usually
prepared upon the small scale by digesting four parts of nitric acid of
specific gravity 1·4, upon one part of sugar, in a glass retort; but on
the large scale, in a series of salt-glazed stoneware pipkins,
two-thirds filled, and set in a water bath. The addition of a little
sulphuric acid has been found to increase the product. 15 pounds of
sugar yield fully 17 pounds of the crystalline acid. This acid exists in
the juice of wood sorrel, the _oxalis acetosella_, in the state of a
bi-oxalate; from which the salt is extracted as an object of commerce in
Switzerland, and sold under the name of salt of sorrel, or sometimes,
most incorrectly, under that of salt of lemons.

Some prefer to make oxalic acid by acting upon 4 parts of sugar, with 24
parts of nitric acid, of specific gravity 1·220, heating the solution in
a retort till the acid begins to decompose, and keeping it at this
temperature as long as nitrous gas is disengaged. The sugar loses a
portion of its carbon, which combining with the oxygen of the nitric
acid, becomes carbonic acid, and escapes along with the deutoxide of
nitrogen. The remaining carbon and hydrogen of the sugar being oxidized
at the expense of the nitric acid, generate a mixture of two acids, the
oxalic and the malic. Whenever gas ceases to issue, the retort must be
removed from the source of heat, and set aside to cool; the oxalic acid
crystallizes, but the malic remains dissolved. After draining these
crystals upon a filter funnel, if the brownish liquid be further
evaporated, it will furnish another crop of them. The residuary mother
water is generally regarded as malic acid, but it also contains both
oxalic and nitric acids; and if heated with 6 parts of the latter acid,
it will yield a good deal more oxalic acid at the expense of the malic.
The brown crystals now formed being, however, penetrated with nitric, as
well as malic acid, must be allowed to dry and effloresce in warm dry
air, whereby the nitric acid will be got rid of without injury to the
oxalic. A second crystallization and efflorescence will entirely
dissipate the remainder of the nitric acid, so as to afford pure oxalic
acid at the third crystallization. Sugar affords, with nitric acid, a
purer oxalic acid, but in smaller quantity, than saw-dust, glue, silk,
hairs, and several other animal and vegetable substances.

Oxalic acid occurs in aggregated prisms when it crystallizes rapidly,
but in tables of greater or less thickness when slowly formed. They lose
their water of crystallization in the open air, fall into powder, and
weigh 0·28 less than before; but still retain 0·14 parts of water, which
the acid does not part with except in favour of another oxide, as when
it is combined with oxide of lead. The effloresced acid contains 20 per
cent. of water, according to Berzelius. By my analysis, the crystals
consist of three prime equivalents, of water = 27, combined, with one of
dry oxalic acid = 36; or in 100 parts, of 42·86 of water with 57·14 of
acid. The acid itself consists of 2 atoms of carbon = 12, + 3 of oxygen
= 24; of which the sum is, as above stated, 36. This acid has a sharp
sour taste, and sets the teeth on edge; half a pint of water, containing
only 1 gr. of acid, very sensibly reddens litmus paper. Nine parts of
water dissolve one part of the crystals at 60° F. and form a solution,
of spec. grav. 1·045, which when swallowed acts as a deadly poison.
Alcohol also dissolves this acid. It differs from all the other acid
products of the vegetable kingdom, in containing no hydrogen, as I
demonstrated (in my paper upon the ultimate analysis of organic bodies,
published in the Phil. Trans. for 1822), by its giving out no muriatic
acid gas, when heated in a glass tube with calomel or corrosive
sublimate.

Oxalic acid is employed chiefly for certain styles of discharge in
calico-printing, (which see), and for whitening the leather of
boot-tops. Oxalate of ammonia is an excellent reagent for detecting lime
and its salts in any solution. The acid itself, or the bi-oxalate of
potash, is often used for removing ink or iron-mould stains from linen.

A convenient plan of testing the value of peroxide of manganese for
bleachers, &c., originally proposed by Berthier, has been since
simplified by Dr. Thomson, as follows. In a poised Florence flask weigh
600 grains of water, and 75 grains of crystallized oxalic acid; add 50
grains of the manganese, and as quickly as possibly afterwards from 150
to 200 grains of concentrated sulphuric acid. Cover the mouth of the
flask with paper, and leave it at rest for 24 hours. The loss of weight
it has now suffered, corresponds exactly to the weight of peroxide of
manganese present; because the quantity of carbonic acid producible by
the reaction of the oxalic acid with the peroxide, is precisely equal to
the weight of the peroxide, as the doctrine of chemical equivalents
shows.


OXIDES, are neutral compounds, containing oxygen in equivalent
proportion.


OXISELS, are salts, consisting of oxygenated acids and oxides, to
distinguish them from the HALOSELS, which are salts consisting of one of
the archæal elements; such as chlorine, iodine, bromine, &c. combined
with metals. See SALT.


OXYGEN _(Oxigène_, Fr.; _Sauerstoff_, Germ.); is a body which can be
examined only in the gaseous form; for which purpose it is most
conveniently obtained in a pure state by exposing chlorate of potash, or
red oxide of mercury, in a glass retort, or recurved tube, to the heat
of a spirit lamp; 100 grains of the salt yield 115 cubic inches of gas.
One pound of nitre, ignited in an iron retort, gives out about 1200
cubic inches of oxygen, mixed with a little nitrogen. The peroxide of
manganese also affords it, either by ignition alone in an iron or
earthen retort, or by a lamp heat in a glass retort, when mixed with
sulphuric acid. Oxygen is void of taste, colour, and smell. It possesses
all the mechanical properties of the atmosphere. Its specific gravity is
1·1026 compared to air 1·0000; whence 100 cubic inches of it weigh 33·85
grains. Combustibles, even iron and diamonds, once kindled, burn in it
most splendidly. It forms 21 parts in 100 by volume of air, being the
constituent essential to the atmospheric functions of supporting animal
and vegetable life, as well as flame.

The full development of this subject in its multifarious relations, will
be discussed in my forthcoming new system of chemistry.

OXYGENATED-MURIATIC, and OXYMURIATIC, are the names originally given by
the French chemists, from false theoretical notions, to chlorine, which
Sir H. Davy proved to be an undecompounded substance.




P.


PACKFONG, is the Chinese name of the alloy called white copper, or
German silver.


PACO, or PACOS, is the Peruvian name of an earthy-looking ore, which
consists of brown oxide of iron, with imperceptible particles of native
silver disseminated through it.

[Illustration: 774]


PADDING MACHINE (_Machine à plaquer_, Fr.; _Klatsch_, or
_Grundirmaschine_, Germ.); in calico-printing, is the apparatus for
imbuing a piece of cotton cloth uniformly with any mordant. In _fig._
774. A B C D represents in section a cast-iron frame, supporting two
opposite standards above M, in whose vertical slot the gudgeons _a b_,
of two copper or bronze cylinders E F, run; the gudgeons of E turn upon
fixed brasses or plummer blocks; but the superior cylinder F rests upon
the surface of the under one, and may be pressed down upon it with
greater or less force by means of the weighted lever _d e f g_, whose
centre of motion is at _d_, and which bears down upon the axle of F. K
is the roller upon which the pieces of cotton cloth intended to be
padded are wound; several of them, being stitched endwise together. They
receive tension from the action of a weighted belt _o_, _n_, which
passes round a pulley _n_ upon the end of the roller K. The trough G,
which contains the colouring matter or mordant, rests beneath the
cylinder upon the table L, or other convenient support. About two inches
above the bottom of the trough, there is a copper dip-roller C, under
which the cloth passes, after going round the guide roller _m_. Upon
escaping from the trough, it is drawn over the half-round stretcher-bar
at I, grooved obliquely right and left, as shown at N, whereby it
acquires a diverging extension from the middle, and enters with a smooth
surface between the two cylinders E F. These are lapped round 6 or 7
times with cotton cloth, to soften and equalize their pressure. The
piece of goods glides obliquely upwards, in contact with one third of
the cylinder F, and is finally wound about the uppermost roller H. The
gudgeon of H revolves in the end of the radius _h_, _k_, which is
jointed at _k_, and movable by a mortise at _i_ along the quadrantal arc
towards _l_, as the roller K becomes enlarged by the convolutions of the
web. The under cylinder E receives motion by a pulley or rigger upon its
opposite end, from a band connected with the driving-shaft of the
printshop. To ensure perfect equability in the application of the
mordant, the goods are in some works passed twice through the trough;
the pressure being increased the second time by sliding the weight _g_
to the end of the lever _d f_.

A view of a padding machine in connexion with the driving mechanism is
given under HOT FLUE; see also STARCHING MACHINE.


PAINT. See ROUGE.


PAINTS, GRINDING OF. There are many pigments, such as common orpiment,
or king’s yellow, and verdigris, which are strong poisons; others which
are very deleterious, and occasion dreadful maladies, such as white
lead, red lead, chrome yellow, and vermillion; none of which can be
safely ground by hand with the slab and muller, but should always be
triturated in a mill. The emanations of white lead cause, first, that
dangerous disease the _colica pictonum_, afterwards paralysis, or
premature decrepitude and lingering death.

[Illustration: 775 776 777 778]

_Figs._ 775, 776, 777, 778. exhibit the construction of a good
colour-mill in three views; _fig._ 775. being an elevation shown upon
the side of the handle, or where the power is applied to the shaft;
_fig._ 776. a second elevation, taken upon the side of the line _c_,
_d_, of the plan or bird’s-eye view, _fig._ 777.

The frame-work A A of the mill is made of wood or cast iron, strongly
mortised or bolted together; and strengthened by the two cross iron bars
B, B. _Fig._ 778. is a plan of the millstones. The lying or nether
millstone C, _fig._ 776, is of cast iron, and is channelled on its upper
face like corn millstones. It is fixed upon the two iron bars B, B; but
may be preferably supported upon the 3 points of adjustable screws,
passing up through bearing-bars. The millstone C is surrounded by a
large iron hoop D, for preventing the pasty-consistenced colour from
running over the edge. It can escape only by the sluice hole E, _fig._
776., formed in the hoop; and is then received in the tub X placed
beneath.

The upper or moving millstone F, is also made of cast iron. The dotted
lines indicate its shape. In the centre it has an aperture with ledges
G, G; there is also a ledge upon its outer circumference, sufficiently
high to confine the colour which may occasionally accumulate upon its
surface. An upright iron shaft H passes into the turning stone, and
gives motion to it. A horizontal iron bevel wheel K, _figs._ 776, 777.,
furnished with 27 wooden teeth, is fixed upon the upper end of the
upright shaft H. A similar bevel wheel L, having the same number of
teeth, is placed vertically upon the horizontal iron axis M, M, and
works into the wheel K. This horizontal axis M, M bears, at one of its
ends, a handle or winch N, by which the workman may turn the millstone
F; and on the other end of the same axis, the fly-wheel O is made fast,
which serves to regulate the movements of the machine. Upon one of the
spokes of the fly-wheel there is fixed, in like manner, a handle P,
which may serve upon occasion for turning the mill. This handle may be
attached at any convenient distance from the centre, by means of the
slot and screw-nut J.

The colour to be ground is put into the hopper R, below which the bucket
S is suspended, for supplying the colour uniformly through the orifice
in the millstone G. A cord or chain T, by means of which the bucket S is
suspended at a proper height for pouring out the requisite quantity of
colour between the stones, pulls the bucket obliquely, and makes its
beak rest against the square upright shaft H. By this means the bucket
is continually agitated in such a way as to discharge more or less
colour, according to its degree of inclination. The copper cistern X,
receives the colour successively as it is ground; and, when full, it may
be carried away by the two handles Z, Z; it may be emptied by the
stopcock Y, without removing the tub.


PAINTS, VITRIFIABLE. See PORCELAIN, POTTERY, and STAINED GLASS.


PALLADIUM; a rare metal, possessed of valuable properties; was
discovered in 1803, by Dr. Wollaston, in native platinum. It constitutes
about 1 per cent. of the Columbian ore, and from 1/4 to 1 per cent. of
the Uralian ore of this metal; occurring nearly pure in loose grains, of
a steel-gray colour, passing into silver white, and of a specific
gravity of from 11·8 to 12·14; also as an alloy with gold in Brazil, and
combined with selenium in the Harz near Tilkerode. Into the
nitro-muriatic solution of native platinum, if a solution of cyanide of
mercury be poured, the pale yellow cyanide of palladium will be thrown
down, which being ignited affords the metal. This is the ingenious
process of Dr. Wollaston. The palladium present in the Brazilian gold
ore may be readily separated as follows: melt the ore along with 2 or 3
parts of silver, granulate the alloy, and digest it with heat in nitric
acid of specific gravity 1·3. The solution containing the silver and
palladium, for the gold does not dissolve, being treated with common
salt or muriatic acid, will part with all its silver in the form of a
chloride. The supernatant liquor being concentrated and neutralized with
ammonia, will yield a rose-coloured salt in long silky crystals, the
ammonia-muriate of palladium, which being washed in ice-cold water, and
ignited, will afford 40 per cent. of metal.

The metal obtained by this process is purer than that by the former; and
if it be fused in a crucible along with borax, by the heat of a powerful
air-furnace or forge, a button of malleable and ductile palladium will
be produced. When a slip of it is heated to redness, it takes a
bronze-blue shade of greater or less intensity, as the slip is cooled
more or less slowly; but if it be suddenly chilled, as by plunging it
into water, it resumes instantly its white lustre. This curious
phenomenon depending upon oxidizement and de-oxidizement, in different
circumstances, serves at once to distinguish palladium from platinum.

Pure palladium resembles platinum, but has more of a silver hue; when
planished by the hammer into a cup, such as that of M. Bréant, in the
museum of the Mint at Paris, it is a splendid steel-white metal, not
liable, like silver, to tarnish in the air. Another cup made by M.
Bréant, weighing 2 lbs. (1 kilogramme), was purchased by Charles X., and
is now in the _garde-meuble_ of the French crown. The specific gravity
of this metal, when laminated, is stated by Dr. Wollaston at 11·8, and
by Vauquelin at 12·1. It melts at from 150° to 160° Wedgewood; and does
not oxidize at a white heat. When a drop of tincture of iodine, is let
fall upon the surface of this metal, and dissipated over a lamp flame, a
black spot remains, which does not happen with platinum. A slip of
palladium has been used with advantage to inlay the limbs of
astronomical instruments, where the fine graduated lines are cut,
because it is bright, and not liable to alteration, like silver.

There are a protoxide and peroxide of palladium. The proto-chloride
consists of 60 of metal and 40 of chlorine; the cyanide, of 67 of metal,
and 33 of cyanogen.


PALM OIL (_Huile de palme_, Fr.; _Palmöl_, Germ.); is obtained, in
Guinea and Guyana, by expressing, as also by boiling, the fruit of the
_avoira elais_. It has an orange colour, a smell of violets, a bland
taste, is lighter than water, melts at 84° Fahr., becomes rancid and
pale by exposure to air, dissolves in boiling alcohol, and consists of
69 parts of oleine, and 31 of stearine, in 100. It is employed chiefly
for making yellow soap. It may be bleached by the action of either
chlorine or oxygen gas, as also by that of light and heat.

_Palm oil, quantity of,_

  +-------+---------+------------+---------+
  |       |         |Retained for|         |
  |       |Imported.|consumption.|Exported.|
  +-------+---------+------------+---------+
  |_Year._| _Cwts._ |  _Cwts._   | _Cwts._ |
  | 1835. | 260,151 |  242,733   | 30,915  |
  | 1836. | 277,017 |  234,357   | 34,379  |
  | 1837. | 223,329 |  214,000   |         |
  +-------+---------+------------+---------+

Duty, 1_s._ 3_d._ per cwt.


PAPER CUTTING. Mr. T. B. Crompton, of Farnworth, Lancashire, who
obtained a patent in May, 1821, for proposing to conduct the newly
formed web of paper in the Fourdrinier machine over heated cylinders,
for the purpose of drying it expeditiously, in imitation of the mode so
long practised in drying calicoes, obtained, along with Enoch Miller,
another, in May, 1828, for cutting the endless web of paper lengthwise,
by revolving circular blades, fixed upon a roller, parallel to a
cylinder, round which the paper is lapped, and progressively unwound.

A patent had been obtained two months before, for certain improvements
in cutting paper, by Mr. Edward Cowper, consisting of a machine, with a
reel on which the web of paper of very considerable length has been
previously wound, in the act of being made in a Fourdrinier’s machine;
this web of paper being of sufficient width to produce two, three, or
more sheets, when cut.

The several operative parts of the machine are mounted upon standards,
or frame-work, of any convenient form or dimensions, and consist: of
travelling endless tapes to conduct the paper over and under a series of
guide rollers; of circular rotatory cutters for the purpose of
separating the web of paper into strips equal to the widths of the
intended sheets; and of a saw-edged knife, which is made to slide
horizontally for the purpose of separating the strips into such portions
or lengths as shall bring them to the dimensions of a sheet of paper.

[Illustration: 779]

The end of the web of paper from the reel _a_, _fig._ 779. is first
conducted up an inclined plane _b_ by hand; it is then taken hold of by
endless tapes extended upon rollers, as in Mr. Cowper’s PRINTING
MACHINE, which see. These endless tapes carry the web of paper to the
roller _c_, which is pressed against the roller _d_ by weighted levers,
acting upon the plummer blocks that its axle is mounted in. The second
roller _d_ may be either of wood or metal, having several grooves formed
round its periphery for the purpose of receiving the edges of the
circular cutters _e_, (see CARD-CUTTING) mounted upon an axle turning
upon bearings in the standards or frame.

In order to allow the web of paper to proceed smoothly between the two
rollers _c_, _d_, a narrow rib of leather is placed round the edges of
one or both of these rollers, for the purpose of leaving a free space
between them, through which the paper may pass without wrinkling.

From the first roller _c_, the endless tapes conduct the paper over the
second _d_, and then under a pressing roller _f_, in which progress the
edges of the circular knives _e_, revolving in the grooves of the second
roller _d_, cut the web of paper longitudinally into strips of such
widths as may be required, according to the number of the circular
cutters and distances between them.

The strips of paper proceed onward from between the knife roller _d_ and
pressing roller _f_, conducted by tapes, until they reach a fourth
roller _g_, when they are allowed to descend, and to pass through the
apparatus designed to cut them transversely; that is, into sheet
lengths.

The apparatus for cutting the strips into sheets is a sliding knife,
placed horizontally upon a frame at _h_, which frame, with the knife
_e_, is moved to and fro by a jointed rod _i_, connected to a crank on
the axle of the pulley _k_. A flat board or plate _l_ is fixed to the
standard frame in an upright position, across the entire width of the
machine; and this board or plate has a groove or opening cut along it
opposite to the edge of the knife. The paper descending from the fourth
roller _g_ passes against the face of this board, and as the carriage
with the knife advances, two small blocks, mounted upon rods with
springs _m m_, come against the paper, and hold it tight to the board or
plate _l_, while the edge of the knife is protruded forward into the
groove of that board or plate, and its sharp saw-shaped teeth passing
through the paper, cut one row of sheets from the descending strips;
which, on the withdrawing of the blocks, falls down, and is collected on
the heap below.

The power for actuating this machine is applied to the reverse end of
the axle, on which the pulley _k_ is fixed, and a band _n_, _n_, _n_,
_n_, passing from this pulley over tension wheels _o_, drives the wheel
_q_ fixed to the axle of the knife roller _d_; hence this roller
receives the rotatory motion which causes it to conduct forward the web
of paper, but the other rollers _c_ and _f_, are impelled solely by the
friction of contact.

The rotation of the crank on the axle of _k_, through the intervention
of the crank-rod _i_, moves the carriage _h_, with the knife, to and fro
at certain periods, and when the spring blocks _m_ come against the
grooved plate _l_, they slide their guide rods into them, while the
knife advances to sever the sheets of paper. But as sheets of different
dimensions are occasionally required, the lengths of the slips delivered
between each return of the knife are to be regulated by enlarging or
diminishing the diameter of the pulley _k_, which will of course retard
or facilitate the rotation of the three conducting rollers, _c_, _d_,
_f_, and cause a greater or less length of the paper to descend between
each movement of the knife carriage.

The groove of this pulley _k_, which is susceptible of enlargement, is
constructed of wedge-formed blocks passed through its sides, and meeting
each other in opposite directions, so that on drawing out the wedges a
short distance, the diameter of the pulley becomes diminished; or by
pushing the wedges further in, the diameter is increased; and a tension
wheel _p_ being suspended in a weighted frame, keeps the band always
tight.

As it is necessary that the paper should not continue descending while
it is held by the blocks _m_, _m_ to be cut, and yet that it should be
led on progressively over the knife roller _d_, the fourth roller _g_,
which hangs in a lever _j_, is made to rise at that time, so as to take
up the length of paper delivered, and to descend again when the paper is
withdrawn. This is effected by a rod _r_, connected to the crank on the
shaft of the aforesaid roller _k_, and also to the under part of the
lever _j_, which lever hanging loosely upon the axle of the knife roller
_d_, as its fulcrum, vibrates with the under roller _g_, so as to effect
the object in the way described.

The patentee states that several individual parts of this machine are
not new, and that some of them are to be found included in the
specifications of other persons, such as the circular cutters _e_, which
are employed by Mr. Dickinson (CARD-CUTTING), and the horizontal cutter
_h_, by Mr. Hansard; he therefore claims only the general arrangement of
the parts in the form of a machine for the purpose of cutting paper, as
the subject of his invention.

[Illustration: 780]

The machine for cutting paper contrived by John Dickinson, Esq. of Nash
Mill, was patented in January, 1829. The paper is wound upon a
cylindrical roller _a_, _fig._ 780., mounted upon an axle, supported in
an iron frame or standard. From this roller the paper in its breadth is
extended over a conducting drum _b_, also mounted upon an axle turning
in the frame or standard, and after passing under a small guide roller,
it proceeds through a pair of drawing or feeding rollers _c_, which
carry it into the cutting machine.

Upon a table _d_, _d_, firmly fixed to the floor of the building, there
is a series of chisel-edged knives _e_, _e_, _e_, placed at such
distances apart as the dimensions of the cut sheets of paper are
intended to be. These knives are made fast to the table, and against
them a series of circular cutters _f_, _f_, _f_, mounted in a swinging
frame _g_, _g_, are intended to act. The length of paper being brought
along the table over the edges of the knives, up to a stop _h_, the
cutters are then swung forwards, and by passing over the paper against
the stationary knives, the length of paper becomes cut into three
separate sheets.

The frame _g_, _g_, which carries the circular cutters _f_, _f_, _f_,
hangs upon a very elevated axle, in order that its pendulous swing may
move the cutters as nearly in a horizontal line as possible; and it is
made to vibrate to and fro by an eccentric, or crank, fixed upon a
horizontal rotatory shaft extending over the drum _b_, considerably
above it, which may be driven by any convenient machinery.

The workmen draw the paper from between the rollers _c_, and bring it up
to the stop _h_, in the intervals between the passing to and fro of the
swing-cutters.

The following very ingenious apparatus for cutting the paper web
transversely into any desired lengths, was made the subject of a patent
by Mr. E. N. Fourdrinier, in June, 1831, and has since been performing
its duty well in many establishments.

[Illustration: 781 782]

_Fig._ 781. is an elevation, taken upon one side of the machine; and
_fig._ 782. is a longitudinal section. _a_, _a_, _a_, _a_, are four
reels, each covered with one continuous sheet of paper; which reels are
supported upon bearings in the frame-work _b_, _b_, _b_. _c_, _c_, _c_,
is an endless web of felt-cloth passed over the rollers _d_, _d_, _d_,
_d_, which is kept in close contact with the under side of the drum _e_,
_e_, seen best in _fig._ 782.

The several parallel layers of paper to be cut, being passed between the
drum _e_, and the endless felt _c_, will be drawn off their respective
reels, and fed into the machine, whenever the driving-band is slid from
the loose to the fast pulley upon the end of the main shaft _f_. But
since the progressive advance of the paper-webs must be arrested during
the time of making the cross cut through it, the following apparatus
becomes necessary. A disc _g_, which carries the pin or stud of a crank
_i_, is made fast to the end of the driving shaft _f_. This pin is set
in an adjustable sliding piece, which may be confined by a screw within
the bevelled graduated groove, upon the face of the disc _g_, at
variable distances from the axis, whereby the eccentricity of the stud
_i_, and of course the throw of the crank, may be considerably varied.
The crank stud _i_ is connected by its rod _j_, to the swinging
curvilinear rack _k_, which takes into the toothed wheel _l_, that turns
freely upon the axle of the feed drum _e_, _e_. From that wheel the arms
_m_, _m_, rise, and bear one or more palls _n_, which work in the teeth
of the great ratchet wheel _o_, _o_, mounted upon the shaft of the drum
_e_.

[Illustration: 783]

The crank-plate _g_ being driven round in the direction of its arrow,
will communicate a see-saw movement to the toothed arc _k_, next to the
toothed wheel _l_ in gearing with it, and an oscillatory motion to the
arms _m_, _m_, as also to their surmounting pall _n_. In its swing to
the left hand, the catch of the pall will slide over the slope of the
teeth of the ratchet wheel _o_; but in its return to the right hand, it
will lay hold of these teeth, and pull them, with their attached drum,
round a part of a revolution. The layers of paper in close contact with
the under half of the drum will be thus drawn forward at intervals, from
the reels, by the friction between its surface and the endless felt, and
in lengths corresponding to the arc of vibration of the pall. The knife
for cutting these lengths transversely is brought into action at the
time when the swing arc is making its inactive stroke, viz., when it is
sliding to the left over the slopes of the ratchet teeth _o_. The extent
of this vibration varies according to the distance of the crank stud
_i_, from the centre _f_, of the plate _g_, because that distance
regulates the extent of the oscillations of the curvilinear rack, and
that of the rotation of the drum _e_, by which the paper is fed forwards
to the knife apparatus. The proper length of its several layers being by
the above described mechanism carried forward over the bed _r_ of the
cutting knife or shears _r_, _v_, whose under blade _r_ is fixed, the
wiper _s_, in its revolution with the shaft _f_, lifts the tail of the
lever _t_, consequently depresses the transverse movable blade _v_ (as
shown in _fig._ 783.), and slides the slanting blades across each other
obliquely, like a pair of scissors, so as to cause a clean cut across
the plies of paper. But just before the shears begin to operate, the
transverse board _u_ descends to press the paper with its edge, and hold
it fast upon the bed _r_. During the action of the upper blade _v_,
against the under _r_, the fall board _u_, is suspended by a cord
passing across pullies from the arm _y_ of the bell-crank lever _t_,
_t_. Whenever the lifter cam _s_, has passed away from the tail of the
bell-crank _t_, the weight _z_, hung upon it, will cause the blade _v_,
and the pinching board _u_, to be moved up out of the way of the next
length of paper, which is regularly brought forward by the rotation of
the drum _e_, as above described. The upper blade of the shears is not
set parallel to the shaft of the drum, but obliquely to it, and is,
moreover, somewhat curved, so as to close its edge progressively upon
that of the fixed blade. The blade _v_ may also be set between two guide
pieces, and have the necessary motion given to it by levers.


PAPER-HANGINGS, called more properly by the French, _papiers peints_.
The art of making paper-hangings, _papier de tenture_, has been copied
from the Chinese, among whom it has been practised from time immemorial.
The English first imported and began to imitate the Chinese
paper-hangings; but being exposed till very lately to a high excise duty
upon the manufacture, they have not carried it to that extent and pitch
of refinement which the French genius has been enabled to do, unchecked
by taxation. The first method of making this paper was stencilling; by
laying upon it, in an extended state, a piece of pasteboard having
spaces cut out of various figured devices, and applying different water
colours with the brush. Another piece of pasteboard with other patterns
cut out was next applied, when the former figures were dry, and new
designs were thus imparted. By a series of such operations, a tolerable
pattern was executed, but with no little labour and expense. The
processes of the calico printer were next resorted to, in which engraved
blocks of the pear or sycamore were employed to impress the coloured
designs.

Paper-hangings may be distinguished into two classes; 1. those which are
really painted, and which are designed in France under the title of
_papiers peints_, with brilliant flowers and figures; and 2. those in
which the designs are formed by foreign matters applied to the paper,
under the name of _papier tontisse_, or flock paper.

The operations common to paper-hangings, of both kinds, may be stated as
follows:--

1. The paper should be well sized.

2. The edges should be evenly cut by an apparatus like the bookbinder’s
press.

3. The ends of each of the 24 sheets which form a piece, should be
nicely pasted together; or a Fourdrinier web of paper should be taken.

4. Laying the grounds, is done with earthy colours or coloured lakes
thickened with size, and applied with brushes.

An expert workman, with one or two children, can lay the grounds of 300
pieces in a day. The pieces are now suspended upon poles near the
ceiling, in order to be dried. They are then rolled up and carried to
the apartment where they are polished, by being laid upon a smooth
table, with the painted side undermost, and rubbed with the polisher.
Pieces intended to be satined, are grounded with fine Paris plaster,
instead of Spanish white; and are not smoothed with a brass polisher,
but with a hard brush attached to the lower end of the swing polishing
rod. After spreading the piece upon the table with the grounded side
undermost, the paper-stainer dusts the upper surface with finely
powdered chalk of Briançon, commonly called talc, and rubs it strongly
with the brush. In this way the satiny lustre is produced.

THE PRINTING OPERATIONS.

Blocks about two inches thick, formed of three separate boards glued
together, of which two are made of poplar, and one (that which is
engraved) of pear-tree or sycamore, are used for printing
paper-hangings, as for calicoes. The grain of the upper layer of wood
should be laid across that of the layer below. As many blocks are
required as there are colours and shades of colour. To make the figure
of a rose, for example, three several reds must be applied in
succession, the one deeper than the other, a white for the clear spaces,
two and sometimes three greens for the leaves, and two wood colours for
the stems; altogether from 9 to 12 for a rose. Each block carries small
pin points fixed at its corners to guide the workman in the insertion of
the figure exactly in its place. An expert hand places these guide pins
so that their marks are covered and concealed by the impression of the
next block; and the finished piece shows merely those belonging to the
first and last blocks.

In printing, the workman employs the same _swimming-tub_ apparatus which
has been described under block printing (see CALICO-PRINTING), takes off
the colour upon his blocks, and impresses them on the paper extended
upon a table in the very same way. The tub in which the drum or frame
covered with calf-skin is inverted, contains simply water thickened with
parings of paper from the bookbinder, instead of the pasty mixture
employed by the calico-printers. In impressing the colour by the block
upon the paper, he employs a lever of the second kind, to increase the
power of his arm, making it act upon the block through the intervention
of a piece of wood, shaped like the bridge of a violin. This tool is
called _tasseau_ by the French. A child is constantly occupied in
spreading colour with a brush upon the calf-skin head of the drum or
sieve, and in sliding off the paper upon a wooden trestle or horse, in
proportion as it is finished. When the piece has received one set of
coloured impressions, the workman, assisted by his little aid called a
_tireur_ (drawer), hooks it upon the drying-poles under the ceiling. A
sufficient number of pieces should be provided to keep the printer
occupied during the whole at least of one day, so that they will be
dried and ready to receive another set of coloured impressions by the
following morning.

All the colours are applied in the same manner, every shade being formed
by means of the blocks, which determine all the beauty and regularity of
the design. A pattern drawer of taste may produce a very beautiful
effect. The history of Psyche and Cupid, by M. Dufour, has been
considered a masterpiece in this art, rivalling the productions of the
pencil in the gradation, softness, and brilliancy of the tints.

When the piece is completely printed, the workman looks it all over, and
if there be any defects, he corrects them by the brush or pencil,
applying first the correction of one colour, and afterwards of the rest.

A final satining, after the colours are dried, is communicated by the
friction of a finely polished brass roller, attached by its end gudgeons
to the lower extremity of a long swing-frame; and acting along the
cylindrical surface of a smooth table, upon which the paper is spread.

[Illustration: 784]

The _fondu_ or rainbow style of paper-hangings, which I have referred to
this place in the article CALICO-PRINTING, is produced by means of an
assortment of oblong narrow tin pans, fixed in a frame, close side to
side, each being about one inch wide, two inches deep, and eight inches
long; the colours of the prismatic spectrum, red, orange, yellow, green,
&c., are put, in a liquid state, successively in these pans; so that
when the oblong brush A, B, with guide ledges _a_, _b_, _c_, is dipped
into them across the whole of the parallel row at once, it comes out
impressed with the different colours at successive points _e_, _e_, _e_,
_e_, of its length, and is then drawn by the paper-stainer over the face
of the woollen drumhead, or sieve of the swimming tub, upon which it
leaves a corresponding series of stripes in colours, graduating into one
another like those of the prismatic spectrum. By applying his block to
the _tear_, the workman takes up the colour in rainbow hues, and
transfers these to the paper. _f_, _f_, _f_, _f_ show the separate
brushes in tin sheaths, set in one frame.

At M. Zuber’s magnificent establishment in the antient château of
Rixheim, near Mulhouse, where the most beautiful French _papiers peints_
are produced, and where I was informed that no less than 3000 blocks are
required for one pattern, I saw a two-colour calico machine employed
with great advantage, both as to taste and expedition. Steam-charged
cylinders were used to dry the paper immediately after it was printed,
as the colours, not being so rapidly absorbed as they are by calico,
would be very apt to spread.

The operations employed for common paper-hangings, are also used for
making flock paper, only a stronger size is necessary for the ground.
The flocks are obtained from the woollen cloth manufacturers, being cut
off by their shearing machines, called _lewises_ by the English workmen,
and are preferred in a white state by the French paper-hanging makers,
who scour them well, and dye them of the proper colours themselves. When
they are thoroughly stove-dried, they are put into a conical fluted
mill, like that for making snuff, and are properly ground. The powder
thus obtained is afterwards sifted by a bolting-machine, like that of a
flour mill, whereby flocks of different degrees of fineness are
produced. These are applied to the paper after it has undergone all the
usual printing operations. Upon the workman’s left hand, and in a line
with his printing table, a large chest is placed for receiving the flock
powders: it is seven or eight feet long, two feet wide at the bottom,
three feet and a half at top, and from 15 to 18 inches deep. It has a
hinged lid. Its bottom is made of tense calf-skin. This chest is called
the _drum_; it rests upon four strong feet, so as to stand from 24 to 28
inches above the floor.

The block which serves to apply the adhesive basis of the
velvet-powders, bears in relief only the pattern corresponding to that
basis, which is formed with linseed oil, rendered drying by being boiled
with litharge, and afterwards ground up with white lead. The French
workmen call this mordant the _encaustic_. It is put upon the cloth
which covers the inverted swimming tub, in the same way as the common
colours are, and is spread with a brush by the _tireur_ (corruptly
styled _tearer_ by some English writers). The workman daubs the blocks
upon the mordant, spreads the pigment even with a kind of brush, and
then applies it by impression to the paper. Whenever a sufficient
surface of the paper has been thus covered, the child draws it along
into the great chest, sprinkling the flock powder over it with his
hands; and when a length of 7 feet is printed, he covers it up within
the drum, and beats upon the calf-skin bottom with a couple of rods to
raise a cloud of flock inside, and to make it cover the prepared portion
of the paper uniformly. He now lifts the lid of the chest, inverts the
paper, and beats its back lightly, in order to detach all the loose
particles of the woolly powder.

By the operation just described, the velvet-down being applied every
where of the same colour, would not be agreeable to the eye, if shades
could not be introduced to relieve the pattern. To give the effect of
drapery, for example, the appearance of folds must be introduced. For
this purpose, when the piece is perfectly dry, the workman stretches it
upon his table, and by the guidance of the pins in his blocks, he
applies to the flock surface a colour in distemper, of a deep tint,
suited to the intended shades, so that he dyes the wool in its place.
Light shades are produced by applying some of his lighter water-colours.

Gold leaf is applied upon the above mordant, when nearly dry; which then
forms a proper gold size; and the same method of application is resorted
to, as for the ordinary gilding of wood. When the size has become
perfectly hard, the superfluous gold leaf is brushed off with a dossil
of cotton wool or fine linen.

The colours used by the paper-hangers are the following:--

1. _Whites._ These are either white-lead, good whitening, or a mixture
of the two.

2. _Yellows._ These are frequently vegetable extracts; as those of weld,
or of Avignon or Persian berries, and are made by boiling the substances
with water. Chrome yellow is also frequently used, as well as the _terra
di Sienna_ and yellow ochre.

3. _Reds_ are almost exclusively decoctions of Brazil wood.

4. _Blues_ are either prussian blue, or blue verditer.

5. _Greens_, are Scheele’s green, a combination of arsenious acid, and
oxide of copper; the green of Schweinfurth, or green verditer; as also a
mixture of blues and yellows.

6. _Violets_ are produced by a mixture of blue and red in various
proportions, or they may be obtained directly by mixing a decoction of
logwood with alum.

7. _Browns, blacks, and grays._ Umber furnishes the brown tints. Blacks
are either common ivory or Frankfort black; and grays are formed by
mixtures of prussian blue and Spanish white.

All the colours are rendered adhesive and consistent, by being worked up
with gelatinous size or a weak solution of glue, liquefied in a kettle.
Many of the colours are previously thickened, however, with starch.
Sometimes coloured lakes are employed. See LAKES.


PAPER, MANUFACTURE OF. (_Papeterie_, Fr.; _Papiermacherkunst_, Germ.)
This most useful substance, which has procured for the moderns an
incalculable advantage over the antients, in the means of diffusing and
perpetuating knowledge, seems to have been first invented in China,
about the commencement of the Christian era, and was thence brought to
Mecca, along with the article itself, about the beginning of the 8th
century; whence the Arabs carried it, in their rapid career of conquest
and colonization, to the coasts of Barbary, and into Spain, about the
end of the 9th or beginning of the 10th century.

By other accounts, this art originated in Greece, where it was first
made from cotton fibres, in the course of the tenth century, and
continued there in common use during the next three hundred years. It
was not till the beginning of the 14th century that paper was made from
linen in Europe, by the establishment of a paper-mill in 1390, at
Nuremberg in Germany. The first English paper-mill was erected at
Dartford by a German jeweller in the service of Queen Elizabeth, about
the year 1588. But the business was not very successful; in consequence
of which, for a long period afterwards, indeed till within the last 70
years, this country derived its supplies of fine writing papers from
France and Holland. Nothing places in a more striking light the vast
improvement which has taken place in all the mechanical arts of England
since the era of Arkwright, than the condition of our paper-machine
factories now, compared with those on the Continent. Almost every good
automatic paper mechanism at present mounted in France, Germany,
Belgium, Italy, Russia, Sweden, and the United States, has either been
made in Great Britain, and exported to these countries, or has been
constructed in them closely upon the English models.

Till within the last 30 years, the linen and hempen rags from which
paper was made, were reduced to the pasty state of comminution requisite
for this manufacture by mashing them with water, and setting the mixture
to ferment for many days in close vessels, whereby they underwent in
reality a species of putrefaction. It is easy to see that the organic
structure of the fibres would be thus unnecessarily altered, nay,
frequently destroyed. The next method employed, was to beat the rags
into a pulp by stamping rods, shod with iron, working in strong oak
mortars, and moved by water-wheel machinery. So rude and ineffective was
the apparatus, that forty pairs of stamps were required to operate a
night and a day, in preparing one hundred weight of rags. The pulp or
paste was then diffused through water, and made into paper by methods
similar to those still practised in the small hand-mills.

About the middle of the last century, the cylinder or engine mode, as it
is called, of comminuting rags into paper pulp, was invented in Holland;
which was soon afterwards adopted in France, and at a later period in
England.

The first step in the paper manufacture, is the sorting of the rags into
four or five qualities. They are imported into this country chiefly from
Germany, and the ports of the Mediterranean. At the mill they are sorted
again more carefully, and cut into shreds by women. For this purpose a
table frame is covered at top with wire cloth, containing about nine
meshes to the square inch. To this frame a long steel blade is attached
in a slanting position, against whose sharp edge the rags are cut into
squares or fillets, after having their dust thoroughly shaken out
through the wire cloth. Each piece of rag is thrown into a certain
compartment of a box, according to its fineness; seven or eight sorts
being distinguished. An active woman can cut and sort nearly one cwt. in
a day.

The sorted rags are next dusted in a revolving cylinder surrounded with
wire cloth, about six feet long, and four feet in diameter, having
spokes about 20 inches long, attached at right angles to its axis. These
prevent the rags from being carried round with the case, and beat them
during its rotation; so that in half an hour, being pretty clean, they
are taken out by the side door of the cylinder, and transferred to the
engine, to be first washed, and next reduced into a pulp. For fine
paper, they should be previously boiled for some time in a caustic lye,
to cleanse and separate their filaments.

[Illustration: 785 786]

The construction of the _stuff-engine_ is represented in _figs._ 785,
786. _Fig._ 785. is the longitudinal section, and _fig._ 786. the plan
of the engine. The large vat is an oblong cistern rounded at the angles.
It is divided by the partition _b_, _b_, and the whole inside is lined
with lead. The cylinder _c_, is made fast to the spindle _d_, which
extends across the engine, and is put in motion by the pinion _p_, fixed
to its extremity. The cylinder is made of wood, and furnished with a
number of blades or cutters, secured to its circumference, parallel to
the axis, and projecting about an inch above its surface. Immediately
beneath the cylinder a block of wood _k_ is placed. This is mounted with
cutters like those of the cylinder, which in their revolution pass very
near to the teeth of the block, but must not touch it. The distance
between these fixed and moving blades is capable of adjustment by
elevating or depressing the bearings upon which the necks _e_, _e_, of
the shaft are supported. These bearings rest upon two levers _g_, _g_,
which have tenons at their ends, fitted into upright mortises, made in
short beams _h_, _h_, bolted to the sides of the engine. The one end of
the levers _g_, _g_, is movable, while the other end is adapted to rise
and fall upon bolts in the beams _h_, _h_, as centres. The front lever,
or that nearest to the cylinder _c_, is capable of being elevated or
depressed, by turning the handle of a screw (not seen in this view),
which acts in a nut fixed to the tenon of _g_, and comes up through the
top of the beam _h_, upon which the head of the screw takes its bearing.
Two brasses are let into the middle of the levers _g_, _g_, and form the
bearings for the shaft of the engine to turn upon. The above-mentioned
vertical screw is used to raise or lower the cylinder, and cause it to
cut coarser or finer, by enlarging or diminishing the space between the
fixed cutters in the block and those in the cylinder.

To the left hand of _i_, _fig._ 785., is a circular breasting made of
boards, and covered with sheet lead; it is curved to fit the cylinder
very truly, and leaves but very little space between the teeth and
breasting; at its bottom, the block _k_ is fixed. The engine is supplied
with water from a pump, by a pipe, which delivers it into a small
cistern, near to and communicating with the engine. A stopcock cuts off
or regulates the supply of water at pleasure, and a grating covered with
hair-cloth is fixed across that small cistern, to intercept any filth
that may be floating in the water; in other cases a flannel bag is tied
round the nose of the stopcock, to act as a filter.

The rags being put into the engine filled with water, are drawn by the
rapid rotation of the cylinder between the two sets of cutters, whereby
they are torn into the finest filaments, and by the impulsion of the
cylinder they are floated over the top of the breasting upon the
inclined plane. In a short time more rags and water are raised into that
part of the engine vat. The tendency in the liquid to maintain an
equilibrium, puts the whole contents of the cistern in slow motion down
the inclined plane, to the left hand of _i_, and round the partition
_b_, _b_, (see the arrow), whereby the rags come to the cylinder again
in the space of about 20 minutes; so that they are repeatedly drawn out
and separated in all directions till they are reduced to the appearance
of a pulp.

[Illustration: 787]

This circulation is particularly useful, by turning over the rags in the
engine, causing them to be presented to the cutter at different angles
every time; otherwise, as the blades always act in one direction, the
comminution would not be so complete. The cutting is performed as
follows: The teeth of the block are set somewhat obliquely to the axes
of the cylinder, as shown by _fig._ 787.; but the teeth of the cylinder
_c_ itself are set parallel to its axis; therefore the cutting edges
meet at a small angle, and come in contact, first at the one end, and
then towards the other, by successive degrees, so that any rags coming
between them, are torn as if between the blades of a pair of forceps.
Sometimes the blades _k_ in the block are bent to an angle in the
middle, instead of being straight and inclined to the cylinder. These
are called elbow plates; their two ends being inclined in opposite
directions to the axis of the cylinder. In either case, the edges of the
plates of the block cannot be straight lines, but must be curved, to
adapt themselves to the curve which a line traced on the cylinder will
necessarily have. The plates or blades are united by screwing them
together, and fitting them into a cavity cut into the wooden block _k_.
Their edges are bevelled away upon one side only.

The block is fixed in its place by being made dovetailed, and truly
fitted into the bottom of the cistern, so that the water will not leak
through its junction. The end of it comes through the woodwork of the
chest, and projects to a small distance on its outside, being kept in
its place by a wedge. By withdrawing this wedge, the block becomes
loose, and can be removed in order to sharpen the cutters, as occasion
may be. This is done at a grindstone, after detaching the plates from
each other.

The cutters of the cylinder, are fixed into grooves, cut in the wood of
the cylinder, at equal distances asunder, round its periphery, in a
direction parallel to its axis. The number of these grooves is twenty,
in the machine here represented. For the _washer_, each groove has two
cutters put into it; then a fillet of wood is driven fast in between
them, to hold them firm; and the fillets are secured by spikes driven
into the solid wood of the cylinder. The _beater_ is made in the same
manner, except that each groove contains three bars and two fillets.

In the operation of the cylinder, it is necessary that it should be
enclosed in a case, or it would throw all the water and rags out of the
engine, in consequence of its great velocity. This case is a wooden box
_m_, _m_, _fig._ 785., enclosed on every side except the bottom; one
side of it rests upon the edge of the vat, and the other upon the edge
of the partition _b_, _b_, _fig._ 786. The diagonal lines _m_, _r_,
represent the edges of wooden frames, which are covered with hair or
wire cloth, and immediately behind these the box is furnished with a
bottom and a ledge towards the cylinder, so as to form a complete
trough. The square figures under _n_, _n_, in _fig._ 785., show the
situation of two openings or spouts through the side of the case, which
conduct to flat lead-pipes, one of which is seen near the upper _g_ in
_fig._ 786., placed by the side of the vat; the beam being cut away from
them. These are waste pipes to discharge the foul water from the engine;
because the cylinder, as it turns, throws a great quantity of water and
rags up against the sieves; the water goes through them, and runs down
to the trough under _n_, _n_, and thence into the ends of the flat
leaden pipes, through which it is discharged. _o_, _o_, _fig._ 785., are
grooves for two boards, which, when put down in their places, cover the
hair sieves, and stop the water from going through them, should it be
required in the engine. This is always the case in the beating engines,
and therefore they are seldom provided with these waste pipes, or at
most on one side only; the other side of the cover being curved to
conform to the cylinder. Except this, the only difference between the
washing engine and the beater, is that the teeth of the latter are
finer, there being 60 instead of 40 blades in the periphery; and it
revolves quicker than the washer, so that it will tear out and comminute
those particles which pass through the teeth of the washer. In small
mills, when the supply of water is limited, there is frequently but one
engine, which may be used both for washing and beating, by adjusting the
screw so as to let the cylinder down and make its teeth work finer. But
the system in all considerable works, is to have two engines at least,
or four if the supply of water be great. The power required for a 5 or 6
vat mill, is about 20 horses in a water-wheel or steam engine.

In the above figures only one engine is shown, namely, the _finisher_;
there is another, quite similar, placed at its end, but on a level with
its surface, which is called the _washer_, in which the rags are first
worked coarsely with a stream of water, running through them to wash and
open their fibres; after this washing they are called _half-stuff_, and
are then let down into the bleaching engine, and next into the _beating_
engine, above described.

By the arrangements of the mill gearing, the two cylinders of the
_washer_ and _beater_ engines make from 120 to 150 revolutions per
minute, when the water-wheel moves with due velocity. The beating engine
is always made to move, however, much faster than the washing one, and
nearly in the ratio of the above numbers.

The vibratory noise of a washing engine is very great; for when it
revolves 120 times per minute, and has 40 teeth, each of which passes by
12 or 14 teeth in the block at every revolution, it will make nearly
60,000 cuts in a minute, each of them sufficiently loud to produce a
most grating growling sound. As the beater revolves quicker, having
perhaps 60 teeth, instead of 40, and 20 or 24 cutters in the block, it
will make 180,000 cuts in a minute. This astonishing rapidity produces a
coarse musical humming, which may be heard at a great distance from the
mill. From this statement, we may easily understand how a modern engine
is able to turn out a vastly greater quantity of paper pulp in a day
than an old mortar machine.

The operation of grinding the rags requires nice management. When first
put into the washing engine they should be worked gently, so as not to
be cut, but only powerfully scrubbed, in order to enable the water to
carry off the impurities. This effect is obtained by raising the
cylinder upon its shaft, so that its teeth are separated considerably
from those of the block. When the rags are comminuted too much in the
washer, they would be apt to be carried off in part with the stream, and
be lost; for at this time the water-cock is fully open. After washing in
this way for 20 or 30 minutes, the bearings of the cylinder are lowered,
so that its weight rests upon the cutters. Now the supply of water is
reduced, and the rags begin to be torn, at first with considerable
agitation of the mass, and stress upon the machinery. In about three or
four hours, the engine comes to work very smoothly, because it has by
this time reduced the rags to the state of _half-stuff_. They are then
discharged into a large basket, through which the water drains away.

The bleaching is usually performed upon the _half-stuff_. At the
celebrated manufactory of Messrs. Montgolfier, at Annonay, near Lyons,
chlorine gas is employed for this purpose with the best effect upon the
paper, since no lime or muriate of lime can be thus left in it; a
circumstance which often happens to English paper, bleached in the
washing engine by the introduction of chloride of lime among the rags,
after they have been well washed for three or four hours by the rotation
of the engine. The current of water is stopped whenever the chloride of
lime is put in. From 1 to 2 pounds of that chemical compound are
sufficient to bleach 1 cwt. of fine rags, but more roust be employed for
the coarser and darker coloured. During the bleaching operation the two
sliders _o_, _o_, _fig._ 785., are put down in the cover of the
cylinder, to prevent the water getting away. The engine must be worked
an hour longer with the chloride of lime, to promote its uniform
operation upon the rags. The cylinder is usually raised a little during
this period, as its only purpose is to agitate the mass, but not to
triturate it. The water-cock is then opened, the boards _m_, _m_ are
removed, and the washing is continued for about an hour, to wash the
salt away; a precaution which ought to be better attended to than it
always is by paper manufacturers.

The half-stuff thus bleached, is now transferred to the beating engine,
and worked into a fine pulp. This operation takes from 4 to 5 hours, a
little water being admitted from time to time, but no current being
allowed to pass through, as in the washing engine. The softest and
fairest water should be selected for this purpose; and it should be
administered in nicely regulated quantities, so as to produce a proper
spissitude of stuff for making paper.

For printing paper, the _sizing_ is given in the beating engine, towards
the end of its operation. The size is formed of alum in fine powder,
ground up with oil; of which mixture about a pint and a half are thrown
into the engine at intervals, during the last half-hour’s beating.
Sometimes a little indigo blue or smalt is also added, when a peculiar
bloom colour is desired. The pulp is now run off into the stuff chest,
where the different kinds are mixed; whence it is taken out as wanted.
The chest is usually a rectangular vessel of stone or wood lined with
lead, capable of containing 300 cubic feet at least, or 3 engines full
of stuff. Many paper-makers prefer round chests, as they admit of
rotatory agitators.

When the paper is made in single sheets, by hand labour, as in the older
establishments, a small quantity of the stuff is transferred to the
working-vat by means of a pipe, and there diluted properly with water.
This vat is a vessel of stone or wood, about 5 feet square, and 4 deep,
with sides somewhat slanting. Along the top of the vat a board is laid,
with copper fillets fastened lengthwise upon it, to make the mould slide
more easily along. This board is called the bridge. The maker stands on
one side; and has to his left hand a smaller board, one end of which is
made fast to the bridge, while the other rests on the side of the vat.
In the bridge opposite to this, a nearly upright piece of wood, called
the ass, is fastened. In the vat there is a copper, which communicates
with a steam pipe to keep it hot; there is also an agitator, to maintain
the stuff in a uniform consistence.

The moulds consist of frames of wood, neatly joined at the corners, with
wooden bars running across, about an inch and a half apart. Across
these, in the length of the moulds, the wires run, from fifteen to
twenty per inch. A strong raised wire is laid along each of the cross
bars, to which the other wires are fastened; this gives the laid paper
its ribbed appearance.

The water-mark is made by sewing a raised piece of wire in the form of
letters, or any figured device, upon the wires of the mould, which makes
the paper thinner in these places. The frame-work of a _wove_ mould is
nearly the same; but instead of sewing on separate wires, the frame is
covered with fine wire cloth, containing from 48 to 64 meshes per inch
square. Upon both moulds a _deckel_, or movable raised edge-frame, is
used; which must fit very neatly, otherwise the edges of the paper will
be rough.

A pair of moulds being laid upon the bridge, the workman puts on the
deckel, brings the mould into a vertical position, dips it about half
way down into the stuff before him, then turning it into a horizontal
position, covers the mould with the stuff and shakes it gently. This is
a very delicate operation; for if the mould be not held perfectly level,
one part of the sheet will be thicker than another. The sheet thus
formed has, however, no coherence; so that by turning the mould, and
dipping the wire cloth surface in the vat, it is again reduced to pulp
if necessary. He now pushes the mould along the small board to the left,
and removes the deckel. Here another workman called the _coucher_
receives it, and places it at rest upon the ass, to drain off some of
the water. Meanwhile the _vat-man_ puts the deckel upon the other mould,
and makes another sheet. The coucher stands to the left side of the vat,
with his face towards the vat-man or maker, on his right is the press
furnished with felt cloths, or porous flannels; a three-inch-thick plank
lies before him on the ground. On this he lays a cushion of felts, and
on this another felt; he then turns the paper wire mould, and presses it
upon the felt, where the sheet remains. He now returns the mould by
pushing it along the bridge. The maker has by this time another sheet
ready for the coucher; which, like the preceding, is laid upon the ass,
and then couched or inverted upon another felt, laid down for the
purpose.

In this way, felts and paper are alternately stratified, till a heap of
six or eight quires is formed, which is from 15 to 18 inches high. This
mass is drawn into the press, and exposed to a force of 100 tons or
upwards. After it is sufficiently compressed, the machine is relaxed,
and the elasticity of the flannel makes the rammer descend (if a
hydraulic press be used) with considerable rapidity. The felts are then
drawn out on the other side by an operative called a _layer_, who places
each felt in succession upon one board, and each sheet of paper upon
another. The coucher takes immediate possession of the felts for his
further operations.

Two men at a vat, and a boy as a layer or lifter, can make about 6 or 8
reams in 10 hours. In the evening the whole paper made during the day,
is put into another press, and subjected to moderate compression, in
order to get quit of the mark of the felt, and more of the water. Next
day it is all separated, a process called parting, and being again
pressed, is carried into the loft. Fine papers are often twice parted
and pressed, in order to give them a proper surface.

The next operation is the drying, which is performed in the following
way. Posts about 10 or 12 feet high are erected at the distance of ten
feet from each other, and pierced with holes six inches apart; two spars
with ropes stretched between them, at the distance of 5 inches from one
another, called a treble or tribble, are placed about 5 feet high
between these posts, supported by pins pushed into the holes in the
posts. The workman takes up 4 or 8 sheets of paper, and puts them upon a
piece of wood in the form of a T; passing this T between the ropes, he
shifts the sheets upon them, and proceeds thus till all the ropes are
full. He then raises the treble, and puts another in its place, which he
fills and raises in like manner. Nine or ten trebles are placed in every
set of posts. The sides of the drying-room have proper shutters, which
can be opened to any angle at pleasure.

When the paper is dry, it is taken down, and laid neatly in heaps to be
sized. Size is made of pieces of skin, cut off by the curriers before
tanning, or sheep’s feet, or any other matter containing much gelatine.
These substances are boiled in a copper to a jelly; to which, when
strained, a small quantity of alum is added. The workman then takes
about 4 quires of paper, spreads them out in the size properly diluted
with water, taking care that they be equally moistened. This is rather a
nice operation. The superfluous size is then pressed out, and the paper
is parted into sheets. After being once more pressed, it is transferred
to the drying-room, but must not be dried too quickly. Three days are
required for this purpose. When the paper is thoroughly dry, it is
carried to the finishing-house, and is again pressed pretty hard. It is
then picked by women with small knives, in order to take out the knots,
and separate the perfect from the imperfect sheets. It is again pressed,
given to the finisher, to be counted into reams, and done up. These
reams are compressed, tied up, and sent to the warehouse for sale. A
good finisher can count 200 reams, or 96,000 sheets in a day.

Hot pressing is executed by placing a sheet of paper between two
smoothed pasteboards, alternately, and between every 50 pasteboards a
heated plate of iron, and subjecting the pile to the press. This
communicates a fine smooth surface to writing-paper.

The grain of the paper is often disfigured by the felts, when they are
too much used, or when the loose fibres do not cover the twisted thread.
The two sides of the felt are differently raised, and that on which the
fibres are longest is applied to the sheets which are laid down. As the
felts have to resist the reiterated action of the press, their warp
should be made stout, of long combed wool, and well twisted. The woof,
however, should be of carded wool, and spun into a soft thread, so as to
render the fabric spongy, and capable of imbibing much water.

This operose and delicate process of moulding the sheets of paper by
hand, has for nearly thirty years past been performed, in many
manufactories, by a machine which produces it in a continuous sheet of
indefinite length which is afterwards cut into suitable sizes, by the
PAPER-CUTTING MACHINE.

In 1799, Louis Robert, then employed in the paper works of Essonne in
France, contrived a machine to make paper of a great size, by a
continuous motion, and obtained for it a patent for 15 years, with a sum
of 8000 francs from the French government, as a reward for his
ingenuity. The specification of this patent is published in the second
volume of _Brevets d’Invention expirés_. M. Leger-Didot, then director
of the said works, bought Robert’s machine and patent for 25,000 francs,
to be paid by instalments. Having become proprietor of this machine,
which, though imperfect, contained the germ of a valuable improvement in
paper-making, M. Didot came over with it to England, where he entered
into several contracts for constructing and working it.

Meanwhile M. L. Didot having failed to fulfil his obligations to Robert,
the latter instituted a law-suit, and recovered possession of his patent
by a decision dated 23d June, 1810. Didot then sent over to Paris the
Repertory of Arts, for Sept. 1808, which contained the specification of
the English patent, with instructions to a friend to secure the improved
machines described in it, by a French patent. The patent was obtained,
but became inoperative in consequence of M. L. Didot failing to return
to France, as he had promised, so as to mount the patent machine within
the two years required by the French patent law. It was not till 1815,
that M. Calla, machine-maker at Paris, constructed the paper apparatus
known in England by the name of Fourdrinier’s, and which, on the
authority of the _Dictionnaire Technologique_, was very imperfect in
comparison of an English-made machine imported about that time into
France. _La construction de ces machines, qui n’offre pourtant rien de
difficile, est restée jusqu’à ce jour exclusivement dans les mains des
Anglais_, is the painful acknowledgment made in 1829, for his
countrymen, by the author of the elaborate article Papeterie in that
national work. If there be nothing difficult in the construction of
these machines, the French mechanicians ought to be ashamed of forcing
their countrymen to seek the sole supply of them in England; for the
principal paper works in France, as those of MM. Canson, Montgolfier,
Thomas Varenne, Firmin Didot, Delcambre, De Maupeon, &c., are mounted
with English-made machines.

The following, for example, are a few of the paper-mills in France which
are mounted with the self-acting machines of Messrs. Bryan Donkin &
Co.:--

  Messrs. Canson, at Annonay.
  M. de la Place, at Jean d’Heures, Bar-le-duc.
  Société anonyme, at Sainte Marie, under M. Delatouche.
  Echarcon près Mennecy, (Seine et Oise).
  Firmin Didot, Mesnil sur l’Estrée.
  M. F. M. Montgolfier, à Annonay.
  Muller, Bouchard, Ondin and Co’s., at Gueures, near Dieppe.
  MM. Richard et Comp. à Plainfoing.
  M. Callot-Bellisle; Vieuze et Chantoiseau.
  M. Bechétaile, near St. Etienne, at Bourg Argental.

It deserves particularly to be remarked, to the honour of English
mechanism, that the proprietors of the first five of the above works
received gold medals at the last exposition of their papers at the
Louvre, and all the rest received medals either of silver or bronze.[37]

  [37] Rapport de Jury Central, par M. Le Baron Charles Dupin, vol. ii.
  p. 278; Paris, 1836.

The following is a true narrative of the rise and progress of the paper
automaton.

M. Leger Didot, accompanied by Mr. John Gamble, an Englishman who had
resided for several years in Paris, obtained permission from the French
government, in 1800, to carry over the small working model of Robert’s
continuous machine, with the view of getting the benefit of English
capital and mechanical skill to bring it into an operative state upon
the great scale. Fortunately for the vigorous development of this embryo
project, which had proved an abortion in France, they addressed
themselves on the one hand, to a mercantile firm equally opulent and
public spirited, and on the other, to engineers distinguished for
persevering energy and mechanical resource. A first patent was granted
to Mr. Gamble on the 20th of April 1801, and a second, for certain
improvements upon the former, on the 7th of June 1803. In January 1804,
Mr. Gamble, for certain considerations, assigned these two patents to
Messrs. Henry and Sealy Fourdrinier, the house above alluded to, who
were at that period, and for several years afterwards, the most
considerable stationers and paper-makers in Great Britain. By an act of
parliament passed on the 4th of August 1807, Mr. Gamble’s privilege of
14 years from April 1801, was prolonged to 15 years after the date of
the act, being an extension of about 7 years upon the original patent.

The proprietors showed good reasons, in the enormous expense of their
experiments, and the national importance of the object, why the patent
should have been extended 14 years from the latter date, and would have
obtained justice from parliament in this respect, but for an unworthy
artifice of Lord Lauderdale in the House of Lords. “He, and he only, was
the person who took the objection,” and, by introducing a regulation in
a standing order of the House of Lords, that none but the original
inventor should have an extension, though Mr. H. Fourdrinier was the
inventor substantially of the operative machine, he defeated the
honourable intentions of his brother peers, whose committee said, “We
will give seven years, and Mr. Fourdrinier may apply again, if it should
turn out that the seven years that we propose to give to Mr. Fourdrinier
should not give sufficient time to afford any chance of his receiving
any remuneration for the expense that he has incurred in introducing
this invention.” The bill passed in the House of Commons for 14 years,
but it was limited by this _ruse_ of Lord Lauderdale to 7, “who put the
standing order upon the books (of the upper house) which prevented
Messrs. Fourdrinier from having any benefit from the invention.”[38]

  [38] See this shabby piece of diplomacy unveiled in the Minutes of
  Evidence taken before the Select Committee of the House of Commons on
  Fourdrinier’s patent; May, 1837.

In February 1808, Mr. Gamble, after losing both his time and money
savings during eight years of irksome diligence, assigned over to
Messrs. Fourdrinier the whole right of his share in the patent to which
he was entitled under the act of parliament.

Dartford in Kent, which had been long conspicuous as the seat of a good
manufactory of paper and paper moulds, was selected by the proprietors
of the patent as the fittest place for realizing their plans; and
happily for them it possessed, in Mr. Hall’s engineering establishment,
every tool requisite for constructing the novel automaton, and in his
assistant Mr. Bryan Donkin, a young and zealous mechanist, who,
combining precision of workmanship with fertility of invention, could
turn his local advantages to the best account. To this gentleman, aided
by the generous confidence of Messrs. Fourdrinier, the glory of rearing
to a stately manhood the helpless bantling of M. L. Didot is entirely
due. In 1803, after nearly three years of intense application, he
produced a self-acting machine for making an endless web of paper, which
was erected at St. Neot’s, under the superintendence of Mr. Gamble, and
performed in such a manner as to surprise every beholder.

Since that important era Mr. Donkin has steadily devoted his whole mind
and means to the progressive improvement of this admirable apparatus;
and has, by the unfailing regularity, precision, promptitude, and
productiveness of its work, earned for himself a place along with Watt,
Wedgewood, and Arkwright, in the temple of mechanical fame.

“_La France_,” says a late official eulogist of her arts, and
interpreter of her sentiments, “ne craint plus la rivalité des autres
peuples pour la fabrication des divers genres de papiers et de
cartons.”[39] After this boast, one would not expect to hear him
immediately confess that in 1823 his country possessed only one
manufactory of the _papier continu_, containing one of the Fourdrinier
machines made at London by Mr. Donkin, for M. Canson, at
Vidalon-les-Annonay; that in 1827 there were only 4 of these machines in
France, and that in 1834 there were not many more than a dozen. He
justly observes, that “this mode being more economical, more rapid, and
more powerful, will become henceforth the only one which can be
practised without loss. Then will disappear the antient system of
hand-work, which likewise involved the inconveniences, we may say
dangers, resulting from combinations among the operatives. The
machine-made papers possess many advantages: they can receive, so to
speak, unlimited dimensions; they preserve a perfectly uniform thickness
throughout all their length; they may be fabricated in every season of
the year; nor do they require to be sorted, trimmed, and hung up in the
drying-house, operations which occasioned great waste, amounting to no
less than one defective sheet out of every five. The continuous paper at
one time retained the impression of the wire-wove web on its under side;
a defect from which it has been freed by a pressure apparatus of Mr.
Donkin, recently imported from England by M. Delatouche.”

  [39] Rapport de Jury Central, sur les Produits de l’Industrie
  Française exposé en 1834, par Le Baron Charles Dupin, Membre de
  l’Institut, Rapporteur-général et Vice President du Jury Central; ii.
  278.

It appears from documents presented to a committee of the House of Lords
in 1807, that the Messrs. Fourdrinier had, by that time, withdrawn from
their stationery business the large sum of 60,000_l._, to further the
object of their patent; so many difficulties did they encounter in
bringing the machinery to its then comparatively complete state, and so
little encouragement or support did they receive from the paper
manufacturers throughout the kingdom.

The patentees laid a statement before the public in 1806, containing the
following comparative estimate of the expense attending seven vats, and
that attending a machine employed upon paper sized in the engine,
performing the same quantity of work as seven vats, at the rate of 12
hours daily.

A MACHINE.

  +-------------------------+-------+-----------+----------+-----------+
  |                         |  Day. |   Week.   |  Month.  |   Year.   |
  |                         +-------+-----------+----------+-----------+
  |                         |_s. d._|_£  s.  d._|_£  s. d._|_£   s. d._|
  |2 Journeymen             | 3  6  | 2   2  0  | 8   8  0 |109   4  0 |
  |2 Ditto                  | 2  6  | 1  10  0  | 6   0  0 | 78   0  0 |
  |2 Finishers              | 3  6  | 2   2  0  | 8   8  0 |109   4  0 |
  |2 Dry workers            | 3  6  |     2  0  | 8   8  0 |109   4  0 |
  |  Parters (none)         |       |           |          |           |
  |  Fire (none)            |       |           |          |           |
  |  Felting                |       |           |          | 24   0  0 |
  |  Washing, ditto         |       |           |          |  5   0  0 |
  |  Wire                   |       |           |          |200   0  0 |
  |1 Man, to keep in repair}|       |           |          |           |
  |  the mill and machine  }|       |           |          |100   0  0 |
  |-                        |       +-----------+----------+-----------+
  |9 Total                  |       | 7  16  0  |31  4  0  |734 12   0 |
  +-------------------------+-------+-----------+----------+-----------+
  |                                                       _£   s. d._  |
  |Expense of 7 vats per annum (see next page), is      2,604  12  0   |
  |A machine doing 7 vats’ work, is, per annum            734  12  0   |
  |                                                  ----------------  |
  |    Balance saved by the machine per annum        _£_1,870   0  0   |
  +--------------------------------------------------------------------+
  |_N. B._--There are other advantages, to the amount of full 400_l._  |
  |per annum, of which manufacturers are well aware, although not taken|
  |into this calculation.                                              |
  +--------------------------------------------------------------------+

SEVEN VATS.

  +---------------------+-------+----------+-----------+-------------+
  |                     |  Day. |  Week.   |  Month.   |    Year.    |
  |                     +-------+----------+-----------+-------------+
  |                     |_s. d._|_£ s. d._ | _£ s. d._ |  _£   s. d._|
  |7 Vatmen, at         | 3  3  | 6 16  6  | 27  6  0  |  354 18  0  |
  |7 Couchers           | 3  1  | 6  9  6  | 25 18  0  |  336 14  0  |
  |7 Layers             | 3  1  | 6  9  6  | 25 18  0  |  336 14  0  |
  |3 Finishers          | 4  0  | 3 12  0  | 14  8  0  |  187  4  0  |
  |6 Dry-workers        | 3  1  | 5 11  0  | 22  4  0  |  288 12  0  |
  |3 Men to go to press,|       |          |           |             |
  |  &c.                | 2  6  | 2  5  0  |  9  0  0  |  117  0  0  |
  |7 Parters (women)    | 1  4  | 2 16  0  | 11  4  0  |  145 12  0  |
  |  Fire               |       | 7  0  0  | 28  0  0  |  364  0  0  |
  |  Felting            |       |          |           |  140  0  0  |
  |  Washing ditto, oil,|       |          |           |             |
  |    soap, fire, &c.  |       | 1 11  6  |  6  6  0  |   81 18  0  |
  |  Moulds             |       |          |           |  140  0  0  |
  |1 Man, and expenses }|       |          |           |             |
  |  of repairing, in  }|       |          |           |             |
  |  keeping in order 7}|       |          |           |             |
  |  vats, vat-presses,}|       |          |           |             |
  |  &c.               }|       |          |           |  112  0  0  |
  |                     |       +----------+-----------+-------------+
  |Total 41 persons.    |       |42 11  0  |170  4  0  |2,604  0  0  |
  +---------------------+-------+----------+-----------+-------------+

In the same statement, it was shown that the expense of making paper by
hand is 16_s._ per cwt., whereas by their machine it is only 3_s._
9_d._; so that upon 432,000 cwts. the quantity annually made in Great
Britain and Ireland (as founded upon the fact that one vat can make 480
cwts. of paper, and that there were 900 vats in the kingdom), the annual
saving by the machine would be 264,600_l._, or 345,600_l._ - 81,000_l._

In a second statement laid before the public in 1807, the patentees
observe that their recently improved machine, from its greater
simplicity, may be erected at a considerably reduced expense. “Mr.
Donkin, the engineer, will engage to furnish machines of the dimensions
specified below, with all the present improvements, at the prices
specified below.

  +------------+-------+---------------------+-----+
  |            |Inches.|If driven by straps. | _£_ |
  |            +-------+---------------------+-----+
  |3 or 4 vats |  30   |between the deckles  |  715|
  |     6 ditto|  40   |  ditto      ditto   |  845|
  |     8 ditto|  44   |  ditto      ditto   |  940|
  |    12 ditto|  54   |  ditto      ditto   |  995|
  |            |       |                     |     |
  |            |       |If driven by wheels. |     |
  |            |       |                     |     |
  |3 or 4 vats |  30   |between the deckles  |  750|
  |     6 ditto|  40   |  ditto      ditto   |  880|
  |     8 ditto|  44   |  ditto      ditto   |  980|
  |    12 ditto|  54   |  ditto      ditto   |1,040|
  +------------+-------+---------------------+-----+

“Instead of 5 men, formerly employed upon 1 machine, 3 are now (in 1813)
fully sufficient, without requiring that degree of attention and skill
which were formerly indispensable.

“In 1806 the machine was capable of doing the work of 6 vats in twelve
hours; it is, however, now capable of doing double that quantity, at
one-fourth of the expense. For by the various improvements enumerated
above, the consumption of wire is reduced nearly one-half, and lasts
above double the time; the quantity of paper produced is doubled; and,
taking into consideration the work which is now performed by the men
over and above their immediate attendance upon the machine, it may be
fairly stated, that the number of men is reduced to one-half;
consequently the expense of wire and labour is reduced to one-fourth of
what it was.

“The other advantages incidental to the nature of the process of making
paper by this machine, may be classed in the following order:--

“1st. That the paper is much superior in strength, firmness, and
appearance, to any which can be made by hand of the same material.

“2d. It requires less drying, less pressing and parting, and
consequently comes sooner to market; for it receives a much harder
pressure from the machine than can possibly be given by any vat press,
and is therefore not only drier, but, on account of the closeness and
firmness of texture, even the moisture which remains is far sooner
evaporated, on exposure to the air, than it would be from the more
spungy or bibulous paper made by hand.

“The superior pressure, and the circumstance of one side of the paper
passing under the polished surface of one of the pressing rollers,
contribute to that smoothness which in hand-made papers can only be
obtained by repeated parting and pressing; consequently a great part of
the time necessarily spent in these operations is saved, and the paper
sooner finished and ready for market.

“3dly. The quantity of broken paper and retree is almost nothing
compared with what is made at the vats.

“4th. The machine makes paper with cold water.

“5th. It is durable, and little subject to be out of repair. The machine
at Two Waters, in Hertfordshire, for the last three years, has not cost
10_l._ a year in repairs.

“6th. As paper mills are almost universally wrought by streams, which
vary considerably in their power from time to time, there will result
from this circumstance a very important advantage in the adoption of the
machine. The common paper mill being limited by its number of vats, no
advantage can be taken of the frequent accessions of power which
generally happen in the course of the year, but, on the contrary, as
scarcely any mills are capable of preparing stuff for twelve vats, every
accession of power to the mill, where a machine is employed, will
increase its produce without any additional expense.

“7th. The manufacturer can suspend or resume his work at pleasure; and
he is besides effectually relieved from the perplexing difficulties and
loss consequent upon the perpetual combinations for the increase of
wages.”

It is a lamentable fact, that the attention required to mature this
valuable invention, and the large capital which it absorbed, led
ultimately to the bankruptcy of this opulent and public-spirited
company; after which disaster no patent dues were collected, though
twelve suits in Chancery were instituted; these being mostly
unsuccessful, on account of some paltry technical objections made to
their well-specified patent, by that unscientific judge Lord Tenterden.
The piratical tricks practised by many considerable paper-makers against
the patentees are humiliating to human nature in a civilized and _soi
disant_ Christian community. Many of them have owned, since the
bankruptcy of the house removed the fear of prosecution, that they owed
them from 2000_l._ to 3000_l._ apiece.

Nothing can place the advantage of the Fourdrinier machine in a stronger
point of view, than the fact of there being 280 of them now at work in
the United Kingdom, making collectively 1600 miles of paper, of from 4
to 5 feet broad, every day; that they have lowered the price of paper 50
per cent., and that they have increased the revenue, directly and
indirectly, by a sum of probably 400,000_l._ per annum. The tissue paper
made by the machine is particularly useful for communicating engraved
impressions to pottery ware; before the introduction of which there was
but a miserable substitute. Messrs. R. and J. Clewes, of Cobridge
potteries, in a letter to Messrs. Fourdrinier, state, “that had not an
improvement taken place in the manufacture of paper, the new style of
engraving would have been of no use, as the paper previously used was of
too coarse a nature to draw from the fair engravings any thing like a
clear or perfect impression; and the Staffordshire potteries, in our
opinion, as well as the public at large, are deeply indebted to you for
the astonishing improvement that has recently taken place, both as
regards china and earthenware, more particularly the latter.” The
following rates of prices justify the above statement:--

                         1814.    1822.    1833.
                        _s. d._  _s. d._  _s. d._
  Demy pottery tissue    12  0    9  6      7  0
  Royal                  16  3   12  0      8  9

“We have adopted a new mode of printing on china and earthenware, which,
but for your improved system of making tissue paper, must have utterly
failed; our patent machine requiring the paper in such lengths as were
impossible to make on the old plan. On referring to our present stock,
we find we have one sheet of your paper more than 1200 yards long.
Signed, Machin and Potts; Burslem, February 25th, 1834.”

I have had the pleasure of visiting more than once the mechanical
workshops of Messrs. Bryan Donkin and Co. in Bermondsey, and have never
witnessed a more admirable assortment of exquisite and expensive tools,
each adapted to perform its part with despatch and mathematical
exactness, though I have seen probably the best machine factories of
this country and the Continent. The man of science will appreciate this
statement, and may perhaps be surprised to learn that the grand mural
circle of 7 feet diameter, made by Troughton, for the Royal Observatory
of Greenwich, was turned with final truth upon a noble lathe in the said
establishment. It has supplied no fewer than 133 complete automatic
paper machines, each of a value of from 1200_l._ to 2000_l._, to
different manufactories, not only in the United Kingdom, but in all
parts of the civilized world; as mentioned in the second paragraph of
the present article. Each machine is capable of making, under the
impulsion of any prime mover, all unmatched by a human eye, and unguided
by a human hand, from 20 to 50 feet in length, by 5 feet broad, of most
equable paper in one minute. Of paper of average thickness, it turns off
30 feet.

[Illustration: 788]

_Fig._ 788. is an upright longitudinal section, representing the machine
in its most complete state, including the drying steam cylinders, and
the compound channelled rollers of Mr. Wilks, subsequently to be
described in detail. The figure in the upper line shows it all in train,
when the paper is to be wound up wet upon the reels E, E, which being
movable round the centre _l_ of a swing-bar, are presented empty, time
about, to receive the tender web. The figure in the under line contains
the steam or drying cylinders; the points O, O, of whose frame, replace,
at the points P, P, the wet-reel frame, F, F, P.

A is the vat, or receiver of pulp from the stuff-chest.

B is the knot strainer of Ibotson (p. 936.), to clear the pulp before
passing on to the wire.

G is the hog, or agitator in the vat. The arrows show the course of the
currents of the pulp in the vat.

I is the apron, or receiver of the water and pulp which escape through
the endless wire, and which are returned by a scoop-wheel into the vat.

_b_ is the copper lip of the vat, over which the pulp flows to the
endless wire, on a leathern apron extending from this lip to about 9
inches over the wire, to support the pulp and prevent its escaping.

_c_, _c_ are the bars which bear up the small tube rollers that support
the wire.

_d_, _d_ are ruler bars, to support the copper rollers over which the
wire revolves.

K is the breast roller, round which the endless wire turns.

N is the point where the shaking motion is given to the machine.

M is the guide roller, having its pivots movable laterally to adjust the
wire and keep it parallel.

L is the pulp roller, or “dandy,” to press out water, and to set the
paper. _r_, is the place of the second, when it is used.

H is the first or wet press, or couching rollers; the wire leaves the
paper here, which latter is couched upon the endless felt _p_; and the
endless wire _o_ returns, passing round the lower couch roller. By Mr.
Donkin’s happy invention of placing these rollers obliquely, the water
runs freely away, which it did not do when their axes were in a vertical
line.

_e_, _e_ are the deckles, which form the edges of the sheet of paper,
and prevent the pulp passing away laterally. They regulate the width of
the endless sheet.

_f_, _f_ are the revolving deckle straps.

R is the deckle guide, or driving-pulley.

_g_, _g_ are tube rollers, over which the wire passes, which do not
partake of the shaking motion; and,

_h_, _h_ are movable rollers for stretching the wire, or brass carriages
for keeping the rollers _g_, _g_ in a proper position.

C is the second press, or dry press, to expel the water in a cold state.

K, K, &c., in the view of the lower line, are the steam cylinders for
drying the endless sheet.

_i_, _i_ are rollers to convey the paper.

_j_, _j_ are rollers to conduct the felt; which serves to support the
paper, and prevent it wrinkling or becoming cockled.

D, D are the hexagonal expanding reels for the steam-dried paper web,
one only being used at a time, and made to suit different sizes of
sheets. _l_ is their swing fulcrum.

F, F, F, F, is the frame of the machine.

The deckle straps are worthy of particular notice in this beautiful
machine. They are composed of many layers of cotton tape, each one inch
broad, and together one half-inch thick, cemented with caoutchouc, so as
to be at once perfectly flexible and water-tight.

The upper end of each of the two carriages of the roller L is of a
forked shape, and the pivots of the roller are made to turn in the cleft
of the forked carriages in such a manner, that the roller may be
prevented from having any lateral motion, while it possesses a free
vibratory motion upwards and downwards; the whole weight of the roller L
being borne by the endless web of woven wire.

[Illustration: 789 790]

The greatest difficulty formerly experienced in the paper manufacture
upon the continuous system of Fourdrinier, was to remove the moisture
from the pulp, and condense it with sufficient rapidity, so as to
prevent its becoming what is called _water-galled_, and to permit the
web to proceed directly to the drying cylinders. Hitherto no invention
has answered so well in practice to remove this difficulty as the
channelled and perforated pulp rollers or dandies of Mr. John Wilks, the
ingenious partner of Mr. Donkin; for which a patent was obtained in
1830. Suppose one of these rollers (see L, in _fig._ 788., and M, M, in
_fig._ 793.,) is required for a machine which is to make paper 54 inches
wide, it must be about 60 inches long, so that its extremities (see
_figs._ 789. and 790.) may extend over or beyond each edge of the sheet
of paper upon which it is laid. Its diameter may be 7 inches. About 8
grooves, each 1-16th of an inch wide, are made in every inch of the
tube; and they are cut to half the thickness of the copper, with a
rectangularly shaped tool. A succession of ribs and grooves are thus
formed throughout the whole length of the tube. A similar succession is
then made across the former, but of 24 in the inch, and on the opposite
surface of the metal, which by a peculiar mode of management had been
prepared for that purpose. As the latter grooves are cut as deep as the
former, those on the inside meet those on the outside, crossing each
other at right angles, and thereby producing so many square holes;
leaving a series of straight copper ribs on the interior surface of the
said tube, traversed by another series of ribs coiled round them on the
outside, forming a cylindrical sieve made of one piece of metal. The
rough edges of all the ribs must be rounded off with a smooth file into
a semicircular form. _Figs._ 789. and 790., A A, are portions of the
ribbed copper tube. _Fig._ 789. shows the exterior, and _fig._ 790. the
interior surface; _b_, _b_ and _b_, _b_ show the plain part at each of
the ends, where it is made fast to the brass rings by rivets or screws;
C, C are the rings with arms, and a centre piece in each, for fixing the
iron pivot or shaft B; one such pivot is fixed by riveting it in each of
the centre pieces of the rings, as shown at _c_, _fig._ 790.; so that
both the said pieces shall be concentric with the rings, and have one
common axis with each other, and with the roller. At _a_, _a_, a groove
is turned in each of the pivots, for the purpose of suspending a weight
by a hook, in order to increase the pressure upon the paper, whenever it
may be found necessary.

[Illustration: 791 792]

_Fig._ 791. is an end view, showing the copper tube and its internal
ribs A, A; the brass rings C, C; arm D, D, D; centre piece E, and pivot
B. _Fig._ 792. is a section of the said ring, with the arms, &c.

The roller is shown at L, _fig._ 788., as lying upon the surface of the
wire-web. The relative position of that perforated roller, and the
little roller _b_, over which it lies, is such that the axis of L is a
little to one side of the axis of _b_, and not in the same vertical
plane, the latter being about an inch nearer the vat end. Hence,
whenever the wire-web is set in progressive motion, it will cause the
roller L to revolve upon its surface; and as the paper is progressively
made, it will pass onwards with the web under the surface of the roller.
Thus the pulpy layer of paper is condensed by compression under the
ribbed roller; while it transmits its moisture through the perforations,
it becomes sufficiently compact to endure the action of the wet press
rollers H, H, and also acquires the appearance of parallel lines, as if
made by hand in a laid mould.

Mr. Wilks occasionally employs a second perforated roller in the same
paper machine, which is then placed at the dotted lines _i_, _i_, _i_.

The patentee has described in the same specification a most ingenious
modification of the said roller, by which he can exhaust the air from a
hollowed portion of its periphery, and cause the paper in its passage
over the roller to undergo the sucking operation of the partial void, so
as to be remarkably condensed; but he has not been called upon to apply
this second invention, in consequence of the perfect success which he
has experienced in the working of the first.

The following is a more detailed illustration of Mr. Wilks’ improved
roller.

[Illustration: 793]

_Fig._ 793. represents two parts of his double-cased exhausting
cylinder.

This consists of two copper tubes, one nicely lining the other; the
inner being punched full of round holes, as at K, K, where that tube is
shown uncovered: a portion of the inner surface of the same tube is
shown at L, L. In this figure also, two portions of the outer tube are
shown at M, M, and N, N; the former being an external, and the latter an
internal view. Here we see that the external tube is the ribbed
perforated one already described; the holes in the inner tube being made
in rows to correspond with the grooves in the outer. The holes are so
distributed that every hole in one row shall be opposite to the middle
of the space left between two holes in the next row, as will appear from
inspection of the figure. The diameter of each of the punched holes
somewhat exceeds the width of each rib in the inside of the outer
cylinder, and every inside groove of this tube coincides with a row of
holes in the former, which construction permits the free transudation or
percolation of the water out of the pulp. At each end of this
double-case cylinder, a part is left at N, N, plain without, and grooved
merely in the inside of the outer tube. The smooth surface allows the
brass ends to be securely fixed; the outer edge of the brass ring fits
tight into the inside of the end of the cylinders.

On the inside of each of these rings there are four pieces which project
towards the centre or axis of the cylinder; two of which pieces are
shown at _a_, _a_, _fig._ 793. in section. _b_, _b_, is a brass ring
with four arms _c_, _c_, _c_, _c_, and a boss or centre piece _d_, _d_.
The outer edge of the last-mentioned ring is also turned cylindrical,
and of such a diameter as to fit the interior of the former ring _o_,
_o_. The two rings are securely held together by four screws. _e_, _e_
is the hollow iron axle or shaft upon which the cylinder revolves. Its
outside is made truly cylindrical, so as to fit the circular holes in
the bosses _d_, _d_, of the rings and arms at each end of the cylinder.
Hence, if the hollow shaft be so fixed that it will not turn, the
perforated cylinder is capable of having a rotatory motion given to it
round that shaft. This motion is had recourse to, when the vacuum
apparatus is employed. But otherwise the cylinder is made fast to the
hollow axle by means of two screw clamps. To one end of the cylinder, as
at _p_, a toothed wheel is attached, for communicating a rotatory motion
to it, so that its surface motion shall be the same as that of the paper
web; otherwise a rubbing motion might ensue, which would wear and injure
both.

The paper stuff or pulp is allowed to flow from the vat A, _fig._ 788.,
on to the surface of the endless wire-web, as this is moving along. The
lines _o_, _o_, _fig._ 788. show the course of the motion of the web,
which operates as a sieve, separating to a certain degree the water from
the pulp, yet leaving the latter in a wet state till it arrives at the
first pair of pressing rollers H, H, between which the web with its
sheet of paper is squeezed. Thick paper, in passing through these
rollers, was formerly often injured by becoming water-galled, from the
greater retention of water in certain places than in others. But Messrs.
Donkin’s cylinder, as above described, has facilitated vastly the
discharge of the water, and enabled the manufacturer to turn off a
perfectly uniform smooth paper.

In _fig._ 788., immediately below the perforated cylinder, there is a
wooden water-trough. Along one side of the trough a copper pipe is laid,
of the same length as the cylinder, and parallel to it; the distance
between them being about one fourth of an inch. The side of the pipe
facing the cylinder is perforated with a line of small holes, which
transmit a great many jets of water against the surface of the cylinder,
in order to wash it and keep it clean during the whole continuance of
the process.

The principle adopted by John Dickinson, Esq., of Nash Mill, for making
paper, is different from that of Fourdrinier. It consists in causing a
polished hollow brass cylinder, perforated with holes or slits, and
covered with wire cloth, to revolve over and just in contact with the
prepared pulp; so that by connecting the cylinder with a vessel
exhausted of its air, the film of pulp, which adheres to the cylinder
during its rotation, becomes gently pressed, whereby the paper is
supposed to be rendered drier, and of more uniform thickness, than upon
the horizontal hand moulds, or travelling wire cloth of Fourdrinier.
When subjected merely to agitation, the water is sucked inwards through
the cylindric cage, leaving the textile filaments so completely
interwoven as, if felted among each other, that they will not separate
without breaking, and, when dry, they will form a sheet of paper of a
strength and quality relative to the nature and preparation of the pulp.
The roll of paper thus formed upon the hollow cylinder is turned off
continuously upon a second solid one covered with felt, upon which it is
condensed by the pressure of a third revolving cylinder, and is thence
delivered to the drying rollers.

Such is the general plan of Mr. Dickinson’s paper machines, into which
he has introduced numerous improvements since its invention in 1809,
many of them secured by patent right; whereby he has been enabled to
make papers of first-rate quality, more particularly for the
printing-press. See _infrà_.

In July 1830, Mr. Ibotson of Poyle, paper manufacturer, obtained a
patent, see B, _fig._ 788., which has proved very successful, for a
peculiar construction of a sieve or strainer. Instead of wire meshes, he
uses a series of bars of gun-metal, laid in the bottom of a box, very
closely together, so that the upper surfaces or the flat sides may be in
the same plane, the edge of each bar being parallel with its neighbour,
leaving parallel slits between them of from about 1-70th to 1-100th of
an inch in width, according to the fineness or coarseness of the
paper-stuff to be strained. As this stuff is known to consist of an
assemblage of very fine flexible fibres of hemp, flax, cotton, &c.,
mixed with water, and as, even in the pulp of which the best paper is
made, the length of the said fibres considerably exceeds the diameter of
the meshes of which common strainers are formed, consequently the
longest and most useful fibres were formerly lost to the paper
manufacturer. Mr. Ibotson’s improved sieve is employed to strain the
paper-stuff previously to its being used in the machine above described.
(see its place at B in the vat.) When the strainer is at work, a quick
vertical and lateral jogging motion is given to it, by machinery similar
to the joggling-screens of corn mills.

Since the lateral shaking motion of the wire-web in the Fourdrinier
machine, as originally made, was injurious to the fabric of the paper,
by bringing its fibres more closely together breadthwise than
lengthwise, thus tending to produce long ribs, or thick streaks in its
substance, Mr. George Dickinson, of Buckland Mill, near Dover, proposed,
in the specification of a patent obtained in February, 1828, to give a
rapid up-and-down movement to the travelling web of pulp. He does not,
however, define with much precision any proper mechanism for effecting
this purpose, but claims every plan which may answer this end. He
proposes generally to mount the rollers, which conduct the horizontal
endless web, upon a vibrating frame. The forepart of this frame is
attached, to the standards of the machine, by hinge joints, and the
hinder part, or that upon which the pulp is first poured out, is
supported by vertical rods, connected with a crank on a shaft below.
Rapid rotatory motion being given to this crank-shaft, the hinder part
of the frame necessarily receives a quick up-and-down vibratory
movement, which causes the water to be shaken out from the web of pulp,
and thus sets the fibres of the paper with much greater equality than in
the machines formerly constructed. A plan similar to this was long ago
introduced into Mr. Donkin’s machines, in which the vibrations were
actuated in a much more mechanical way.

John Dickinson, Esq., of Nash Mill, obtained a patent in October, 1830,
for a method of uniting face to face two sheets of pulp by means of
machinery, in order to produce paper of extraordinary thickness. Two
vats are to be supplied with paper stuff as usual; in which two hollow
barrels or drums are made to revolve upon axles driven by any first
mover; an endless felt is conducted by guide rollers, and brought into
contact with the drums; the first drum gives off the sheet of paper pulp
from its periphery to the felt, which passing over a pressing roller, is
conducted by the felt to that part of a second drum which is in contact
with another pressing roller. A similar sheet of paper pulp is now given
off from the second drum, and it is brought into contact with the former
by the pressure of its own roller. The two sheets of paper pulp thus
united are carried forward by the felt over a guide roller, and onward
to a pair of pressing rollers, where by contact the moist surfaces of
the pulp are made to adhere, and to constitute one double thick sheet of
paper, which, after passing over the surfaces of hollow drums, heated by
steam, becomes dry and compact. The rotatory movements of the two
pulp-lifting drums must obviously be simultaneous, but that of the
pressing rollers should be a little faster, because the sheets extend by
the pressure, and they should be drawn forward as fast as they are
delivered, otherwise creases would be formed. Upon this invention is
founded Mr. Dickinson’s ingenious method of making safety-paper for
Post-office stamps, by introducing silk fibres, &c., between the two
laminæ.

The following contrivance of the same inventive manufacturer is a
peculiarly elegant mechanical arrangement, and is likely to conduce to
the perfection of machine-made paper. I have already described Mr.
Ibotson’s excellent plan of parallel slits, or gridiron strainers, which
has been found to form paper of superior quality, because it permits all
the elongated tenacious fibres to pass, which give strength to the
paper, while it intercepts the coarser knots and lumps of the paste,
that were apt to spoil its surface. Mr. Turner’s circular wire sieves,
presently to be noticed, may do good work, but they cannot compete with
Mr. Dickinson’s present invention, which consists in causing the diluted
paper pulp to pass between longitudinal apertures, about the
hundred-and-fifteenth part of an inch wide, upon the surface of a
revolving cylinder.

The pulp being diluted to a consistency suitable for the paper machine,
is delivered into a vat, of which the level is regulated by a waste
pipe, so as to keep it nearly full. From this vat there is no other
outlet for the pulp, except through the wire-work periphery of the
revolving cylinder, and thence out of each of its ends into troughs
placed alongside, from which it is conducted to the machine destined to
convert it into a paper web.

The revolving cylinder is constructed somewhat like a squirrel cage, of
circular rods, or an endless spiral wire, strengthened by transverse
metallic bars, and so formed that the spaces between the rings are
sufficient to allow the slender fibres of the pulp to pass through, but
are narrow enough to intercept the knots and other coarse impurities,
which must of course remain, and accumulate in the vat. The spaces
between the wires of the squirrel cage may vary from the interval above
stated, which is intended for the finest paper, to double the distance
for the coarser kinds.

It has been stated that the pulp enters the revolving cylinders solely
through the intervals of the wires in the circumference of the cylinder;
these wires or rods are about three-eighths of an inch broad without,
and two-eighths within, so that the circular slits diverge internally.
The rods are one quarter of an inch thick, and are riveted to the
transverse bars in each quadrant of their revolution, as well as at
their ends to the necks of the cylinder.

During the rotation of the cylinder, its interstices would soon get
clogged with the pulp, were not a contrivance introduced for creating a
continual vertical agitation in the inside of the cylinder. This is
effected by the up-and-down motion of an interior agitator or plunger,
nearly long enough to reach from the one end of the cylinder to the
other, made of stout copper, and hollow, but water-tight. A metal bar
passes through it, to whose projecting arm at each end a strong link is
fixed; by these two links it is hung to two levers, in such a way that
when the levers move up and down, they raise and depress the agitator,
but they can never make it strike the sides of the cylinder. Being
heavier than its own bulk of water, the agitator, after being lifted by
the levers, sinks suddenly afterwards by its weight alone.

The agitator’s range of up-and-down movement should be about one inch
and a quarter, and the number of its vibrations about 80 or 100 per
minute; the flow of the pulp through the apertures is suddenly checked
in its descent, and promoted in its ascent, with the effect of
counteracting obstructions between the ribs of the cylinder.

The sieve cylinder has a toothed wheel fixed upon the tubular part of
one of its ends, which works between two metal flanches made fast to the
wooden side of the vat, for the purpose of keeping the pulp away from
the wheel; and it is made to revolve by a pinion fixed on a spindle,
which going across the vat, is secured by two plummer blocks on the
outside of the troughs, and has a rotatory motion given to it by an
outside rigger or pulley, by means of a strap from the driving shaft, at
the rate of 40 or 50 revolutions per minute. This spindle has also two
double eccentrics fixed upon it, immediately under the levers, so that
in every revolution it lifts those levers twice, and at the same time
lifts the agitator.

The diameter of the sieve cylinder is not very material, but 14 inches
have been found a convenient size; its length must be regulated
according to the magnitude of the machine which it is destined to supply
with pulp. One, four feet long in the cage part, is sufficient to supply
a machine of the largest size in ordinary use, viz., one capable of
making paper 4 feet 6 inches wide. When the cylinder is of this length,
it should have a wheel and pinion at each end.

Metal flanches are firmly fixed to the sides of the vat, with a
water-tight joint, and form the bearings in which the cylinder works.

Mr. Turner of Bermondsey, paper-maker, obtained a patent in March, 1831,
for a peculiar strainer, designed to arrest the lumps mixed with the
finer paper pulp, whereby he can dispense with the usual vat and hog in
which the pulp is agitated immediately before it is floated upon the
endless wire-web of the Fourdrinier apparatus. His strainer may also be
applied advantageously to hand paper machines. He constructs his sieves
of a circular form, by combining any desirable number of concentric
rings of metal, with small openings between them, from the 50th to the
100th part of an inch wide. In order to facilitate the passage of the
fine pulp and water, the sieves receive a vibratory motion up and down,
which supersedes the hog employed in other paper-making machines.

A mechanism to serve the same purpose as the preceding, in which Mr.
Ibotson’s plan of a parallel rod-strainer is modified, was made the
subject of a patent by Mr. Henry Brewer, of Surrey Place, Southwark, in
March, 1832. He constructs square boxes with gridiron bottoms, and gives
a powerful up-and-down vibration in the pulp tub, by levers, rotatory
shafts, and cranks.

As the contrivance is not deficient in ingenuity, and may be useful, I
shall describe this mode of adapting his improved strainers to a vat in
which paper is to be made by hand moulds. A hog (or churning rotator) is
employed for the purpose of agitating the pulp at the bottom of the vat,
in which the sieve is suspended from a crank-shaft, or in any other way,
so as to receive the up-and-down vibratory motion for the purpose of
straining the pulp. The pulp may be supplied from a chest, and passed
through a cock into a trough, by which it is conveyed to the strainers.

A pipe from the bottom of the vat leads into a lifter-box, which is
designed to convey thin pulp into the sieve, in order to dilute that
which is delivered from the chest. This pipe also allows the small
lumps, called rolls, to be re-sifted. The pressure of the pulp and water
in the vat forces the pulp up the pipe into the lifter-box, whence it is
taken by rotatory lifters, and discharged into a trough, where it runs
down and mixes with the thick pulp from the chest, as before mentioned.
By these means the contents of the vat are completely strained or sifted
over again in the course of almost every hour.

A patent was obtained for a paper-pulp strainer by Mr. Joseph Amies, of
Loose, in the county of Kent, paper manufacturer, who makes the bottoms
of his improved strainers with plates of brass or other suitable metal,
and forms the apertures for the fine fibres of pulp to pass through, by
cutting short slits through such plates, taking care that as much metal
is left between the ends of each short slit and the next following as
will properly brace or stiffen the ribs of the strainer; and he prefers
that the end of one slit shall be nearly opposite to the middle of the
two slits next adjoining it, which is commonly called blocking the
joints. This is for giving rigidity to the bottom of the strainer, and
constitutes the main feature of his improvement. The bottoms of sieves
previously constructed with long metallic rods, he considers to be
liable to lateral vibration in use, and thus to have permitted knots and
lumps to pass through their expanded intervals. This objection is not
applicable to Mr. Dickinson’s squirrel-cage strainer, of which the ribs
may be made rigid by a sufficient number of transverse bars; nor in fact
is it applicable to Mr. Ibotson’s original strainer, as it is admirably
constructed by Messrs. Donkin and Co. Each bar which they make being
inflexible by a feathered rib, is rendered perfectly straight in its
edge by grinding with emery upon a flat disc-wheel of block tin, and of
invariable length, by a most ingenious method of turning each set of
bars in a lathe. The bars are afterwards adjusted in the metallic
sieve-frame, or chest, at any desired distance apart, from the 120th to
the 60th of an inch, in such a manner as secures them from all risk of
derangement by the vibratory or jogging motion in shaking the pulpy
fibres through the lineal intervals between them.

Mr. James Brown, paper manufacturer, of Esk mills, near Edinburgh,
obtained a patent in May, 1836, for a particular mode of applying
suction to the pasty web in the Fourdrinier’s machine. He places a
rectangular box transversely beneath the horizontal wire cloth, without
the interposition of any perforated covering, such as had been tried in
the previously constructed vacuum machines, and which he considers to
have impeded their efficacy in condensing the pulp and extracting the
water.

Upon this and all similar contrivances for making a partial vacuum under
the pulpy paper web, it may be justly remarked, that they are more apt
to injure than improve the texture of the article; since when the
suction is unequally operative, it draws down not only the moisture, but
many of the vegetable fibres, causing roughnesses, and even numerous
small perforations in the paper.

A modification of Mr. Dickinson’s cylinder-mould continuous paper
machine was made the subject of a patent in Nov. 1830, by Mr. John Hall,
jun., of Dartford, as communicated to him by a foreigner residing
abroad. The leading feature of the invention is a mode of supplying the
vat in which the wire cylinder is immersed with a copious flow of water,
for the purpose of creating a considerable pressure upon the external
surface of the cylinder, and thereby causing the fibres of the paper
pulp to adhere to the mould.

There is a semi-cylindrical trough, in which the mould is immersed, and
made to revolve by any convenient means. The pulp is transferred from
the vat into that vessel at its bottom part. On the side of the
drum-mould opposite to the vat, there is a cistern into which a copious
flow of water is delivered, which passes thence into the
semi-cylindrical trough. In the interior of the cylindrical mould, a
bent or syphon tube is introduced, on the horizontal part of which tube,
inside, the mould revolves. This tube is connected at the outside to a
pump, by which the water is drawn from the interior of the cylindrical
mould. Thus the water in the semi-cylindrical trough, on the outside of
the drum, is kept at a considerably higher level than it is within; and
consequently the pressure of the water, as it passes through the wire
gauze, will, it is supposed, cause the fibres of the paper pulp to
adhere to the circumference of the mould. The water which is withdrawn
from the interior of the drum by the recurved tube, is conducted round
into the cistern, where its discharge is impeded by several vertical
partitions, which make the water flow in a gentle stream into the
semi-cylindrical mould vat. In order to keep the pulp properly agitated
in the mould vat, a segment frame, having rails extended across the vat,
is moved to and fro; as the drum mould goes round, the fibres of the
pulp are forced against its circumference, and as the water passes
through, the fibres adhere, forming the sheet of paper, which, on
arriving at a couching roller above, is taken up as usual by an endless
felt, conducted away to the drying apparatus, and thence to the reel to
be wound up.

The patentee claims merely the application of a pump to draw the water
from the interior of the mould drum, and to throw it upon its external
surface.

A rag-cutting and lacerating machine was patented by Mr. Henry Davy, of
Camberwell, in September, 1833, being a communication from a foreigner
residing abroad. The machine consists of an endless feeding-cloth, by
which the rough rags supplied by the attendants are progressively
conducted forwards to a pair of feed-rollers (see COTTON, _spinning_),
and on passing through these rollers, the rags are subjected to the
operation of rotatory cutters, acting against a fixed or ledger blade,
which cut and tear them to pieces. Thence the rags pass down an inclined
sieve, upon which they are agitated to separate the dust. The cleaned
fragments are delivered on to a horizontal screen or sorting table, to
suffer examination. When picked here, they are ready for the
pulp-engine. A distinct representation of this machine is given in
Newton’s Journal, conjoined series, vol. iv. pl. IX. _fig._ 1.

Mr. Jean Jacques Jequier obtained a patent in August, 1831, for a mode
of making paper on the continuous machine with wire-marks. The proposed
improvement consists merely in the introduction of a felted pressing
roller, to act upon the paper after it has been discharged from the
mould, and need not therefore be particularly described.

In August, 1830, Mr. Thomas Barratt, paper-maker, of St. Mary Cray, in
the county of Kent, obtained a patent for an apparatus by which paper
may be manufactured in a continuous sheet, with the water-mark and
maker’s name, so as to resemble in every respect paper made by hand, in
moulds the size of each separate sheet. On the wire web, at equal
distances apart, repetitions of the maker’s name or other device is
placed, according to the size of the paper when cut up into single
sheets. In manufacturing such paper, the ordinary method of winding upon
a reel cannot be employed; and therefore the patentee has contrived a
compensating reel, whose diameter diminishes at each revolution, equal
to the thickness of a sheet of paper. See Newton’s Journal, C. S. vol.
vii. p. 285.

For Mr. Lemuel Wellman Wright’s series of improvements in the
manufacture of paper, specified in his patent of November, 1834, I must
refer to the above Journal, C. S., vol. viii. p. 86.

A committee of the _Société d’Encouragement_, of Paris, made researches
upon the best composition for sizing paper in the vat, and gave the
following recipe:--

  100 kilogrammes of dry paper stuff.
   12     --         starch.
    1     --         rosin, previously dissolved in 500 grammes of
                     carbonate of soda.
   18 pails of water.

M. Braconnot proposed the following formula in the 23d volume of the
_Annales de Chimie et de Physique_:--To 100 parts of dry stuff, properly
diffused through water, add a boiling uniform solution of 8 parts of
flour, with as much caustic potash as will render the liquor clear. Add
to it one part of white soap previously dissolved in hot water. At the
same time heat half a part of rosin with the requisite quantity of weak
potash lye for dissolving the rosin; mix both solutions together, and
pour into them one part of alum dissolved in a little water.

Those who colour prints, size them previously with the following
composition:--4 ounces of glue, and 4 ounces of white soap dissolved in
3 English pints of hot water. When the solution is complete, two ounces
of pounded alum must be added, and as soon as the composition is made
homogeneous by stirring, it is ready for use. It is applied cold with a
sponge, or rather with a flat camel’s hair brush. Ackermann’s liquor, as
analyzed by Vauquelin, may be made for sizing paper as follows:--

  100 kilogrammes of dry stuff.
    4     --         glue.
    8     --         resinous soap.
    8     --         alum.

The soap is made from 4·8 kilos. of pounded rosin, and 2·22 crystals of
carbonate of soda, dissolved in 100 litres of water. It is then boiled
till the mixture becomes quite uniform; the glue, previously softened by
12 hours’ maceration in cold water, is to be next added; and when this
is totally dissolved, the solution of alum in hot water is poured in.
Three quarts of this size were introduced into the vat with the stuff,
and well mixed with it. The paper manufactured with this paste seemed to
be of excellent quality, and well sized.

The Chinese, in manufacturing paper, sometimes employ linen rags, as we
do; at other times, the fibres of the young bamboo; of the mulberry; the
envelope of the silk-worm cocoon; also a tree, unknown to our botanists,
which the natives call _chu_ or _ko-chu_; cotton down, and especially
the cotton tree. The processes pursued in China to make paper with the
inner bark of their _paper-tree_ (_Broussonetia-papyrifera_,) or Chinese
mulberry, have been described at great length in the bulletin of the
Société d’Encouragement, for 1826, p. 226; but they will hardly prove
serviceable to a European manufacturer. That tree has been acclimated in
France.

Chinese paper is not so well made as the good paper of Europe; it is not
so white, it is thinner, and more brittle, but extremely soft and silky.
The longitudinal tenacity of its filaments, however, renders it fitter
for the engraver than our best paper. The Chinese, after triturating,
grinding, and boiling the bamboo, set the paste to ferment in a heap
covered with mats. Chinese paper is readily recognised, because it is
smooth on one side, and bears on the other, the marks of the brush with
which it is finished, upon smooth tables, in order to dry it flat. The
kind employed for engravings is in sheets four feet long, and two broad.
It is made of the bamboo; their myrtle-tree paper would be too strong
for this purpose.

_Tracing Paper._

The best paper of this kind, sometimes superfluously called vegetable
paper, is made of the refuse of the flax mills, and prepared by the
engine without fermentation. It thus forms a semi-transparent paste, and
affords a transparent paper. Bank-note paper is made of the same
materials, but they always undergo a bleaching with chloride of lime.
Great nicety is required in drying this kind of paper. For this purpose,
each sheet must be put between two sheets of gray paper in the press;
and this gray paper must be renewed several times, to prevent the
bank-note paper from creasing.

_Paper of Safety or Surety; Papier de Sureté._

This subject has occupied the attention of the French Academy for many
years, in consequence of the number of frauds committed upon the stamp
revenue in France. One of the best methods of making a paper which would
evince whether any part of a writing traced upon it had been tampered
with or discharged, is to mix in the vat two kinds of pulp, the one
perfectly white, the other dyed of any colour easily affected by
chlorine, acids, and alkalis. The latter stuff being mingled with the
former in any desired proportion, will furnish a material for making a
paper which will contain coloured points distributed throughout all its
substance, ready to show, by the changes they suffer, whether any
chemical reaction has been employed.

Quantity of Paper charged with Duties of Excise, in the United Kingdom,
in

  +--------------------------+-------------+-------------+-------------+
  |                          |    1834.    |    1835.    |    1836.    |
  +--------------------------+-------------+-------------+-------------+
  |                          |    _lbs._   |    _lbs._   |    _lbs._   |
  |First class               | 54,053,721  | 56,179,555  | 66,202,689  |
  |Second class              | 16,552,168  |  7,863,095  | 15,906,258  |
  |Pasteboard, millboard, &c.|     49,392  |     49,772  |     36,340  |
  |                          |   _yards._  |   _yards._  |   _yards._  |
  |Stained                   |  8,749,144  |  8,247,931  |  8,032,577  |
  +--------------------------+-------------+-------------+-------------+
  |                          | _£    s. d._| _£    s. d._| _£    s. d._|
  |Amount of duty,           |             |             |             |
  |    first class           |675,671 10  0|702,244  9  0|651,699  0  0|
  | --   second class        |103,451  0  0|111,644  0  0| 99,414  0  0|
  | --   pasteboard, &c.     | 54,689  0  0| 54,548 15  0| 39,557  0  0|
  | --   stained             | 63,795 16  0| 60,141  0  0| 22,112  0  0|
  +--------------------------+-------------+-------------+-------------+

The late reduction of the duty, from 3_d._ to 1-1/2_d._ per lb., upon
paper of the first class, viz., on all descriptions of it, except that
made out of tarred ropes only, has been already attended with
considerable benefit to the manufacture, and would have acted with much
greater effect, but for the American crisis. The gross amount of the
paper duty in the year ending 5th January, 1836, was 831,057_l._, and in
the year ending 5th January, 1838, it was 554,497_l._; instead of being
little more than one half, as might have been the case from the
reduction of the duty, which only came into full operation in the year
1837. At the same time that the tax on common paper was reduced, that
upon stained paper was repealed altogether. The effect of the diminution
consequently made in the price of paper-hangings, has been so great as
nearly to double the consumption of the country, while the manufacture
appears to be still rapidly on the increase.

Declared Value of Stationery and Printed Books exported in

  +------+-----------+--------------+-----------+
  |Years.|Stationery.|Printed Books.|   Total.  |
  +------+-----------+--------------+-----------+
  | 1827 |_£_195,110 | _£_107,199   |_£_302,309 |
  | 1828 |   208,532 |    102,874   |   311,406 |
  | 1829 |   190,652 |    109,878   |   300,530 |
  | 1830 |   171,848 |     95,874   |   267,722 |
  | 1831 |   179,216 |    101,110   |   280,326 |
  | 1832 |   177,718 |     93,038   |   270,756 |
  | 1833 |   211,518 |    124,535   |   336,053 |
  | 1834 |   211,459 |    122,595   |   334,054 |
  | 1835 |   259,105 |    148,318   |   407,423 |
  | 1836 |   301,121 |    178,945   |   480,066 |
  +------+-----------+--------------+-----------+

Till the paper trade shall escape entirely from the clutches of its
antient dry-nurse, the excise, neither it nor the book trade can acquire
the same ascendancy in exportation which all other articles of British
manufactures have over the French.

The Value of Stationery exported in France, from 1833, was,--

  Cartons lustrés (polished pasteboards for the cloth
  manufacture)                                            18,992 francs
  Cartons en feuilles (pasteboard in sheets)               6,352   --
  Cartons moulés (papier-maché)                          215,376   --
  Cartons coupés et assemblés                             54,184   --
  Wrapping paper                                         178,544   --
  White paper, and rayé (ruled) pour musique           2,903,075   --
  Coloured paper in reams                                 58,541   --
  Stained paper (paper hangings) in _rouleaux_,        1,885,387   --
  Silk paper                                               3,240   --
                                                       ---------
  Total (= _£_208,000)                                 5,323,621 francs.


PARAFFINE. Distil beech-tar to dryness, rectify the heavy oil which
collects at the bottom of the receiver, and when a thick matter begins
to rise, set aside what is distilled, and urge the heat moderately as
long as any thing more distils. Pyrélaine passes over, containing
crystalline scales of paraffine. This mixture being digested with its
own volume of alcohol of 0·833, forms a limpid solution, which is to be
gradually diluted with more alcohol, till its bulk becomes 6 or 8 times
greater. The alcohol, which at first dissolves the whole, lets the
paraffine gradually fall. The precipitate being washed with cold
alcohol till it becomes nearly colourless, and then dissolved in boiling
alcohol, is deposited on cooling in minute spangles and needles of pure
paraffine.

Or the above mixture may be mixed with from 1/4 to 1/2 its weight of
concentrated sulphuric acid, and subjected for 12 hours to digestion, at
a heat of 150° F., till, on cooling, crystals of paraffine appear upon
the surface. These are to be washed with water, dissolved in hot
alcohol, and crystallized. Paraffine is a white substance, void of taste
and smell, feels soft between the fingers, has a specific gravity of
0·87, melts at 112° Fahr., boils at a higher temperature with the
exhalation of white fumes, is not decomposed by dry distillation, burns
with a clear white flame without smoke or residuum, does not stain
paper, and consists of 85·22 carbon, and 14·78 hydrogen; having the same
composition as olefiant gas. It is decomposed neither by chlorine,
strong acids, alkalis, nor potassium; and unites by fusion with sulphur,
phosphorus, wax, and rosin. It dissolves readily in warm fat oils, in
cold essential oils, in ether, but sparingly in boiling absolute
alcohol. Paraffine is a singular solid bicarburet of hydrogen; it has
not hitherto been applied to any use, but it would form admirable
candles.


PARCHMENT. (_Parchemin_, Fr.; _Pergament_, Germ.) This writing material
has been known since the earliest times, but is now made in a very
superior manner to what it was anciently, as we may judge by inspection
of the old vellum and parchment manuscripts. The art of making parchment
consists in certain manipulations necessary to prepare the skins of
animals of such thinness, flexibility, and firmness, as may be required
for the different uses to which this substance is applied. Though the
skins of all animals might be converted into writing materials, only
those of the sheep or the she-goat are used for parchment; those of
calves, kids, and dead-born lambs for vellum; those of the he-goat,
she-goat, and wolves for drum-heads; and those of the ass for
battledores. All these skins are prepared in the same way, with slight
variations, which need no particular detail.

They are first of all prepared by the leather-dresser. After they are
taken out of the lime-pit, shaved, and well washed, they must be set to
dry in such a way as to prevent their puckering, and to render them
easily worked. The small manufacturers make use of hoops for this
purpose, but the greater employ a _herse_, or stout wooden frame. This
is formed of two uprights and two cross-bars solidly joined together by
tenons and mortises, so as to form a strong piece of carpentry, which is
to be fixed up against a wall. These four bars are perforated all over
with a series of holes, of such dimensions as to receive slightly
tapered box-wood pins, truly turned, or even iron bolts. Each of these
pins is transpierced with a hole like the pin of a violin, by means of
which the strings employed in stretching the skin may be tightened.
Above the _herse_, a shelf is placed, for receiving the tools which the
workman needs to have always at hand. In order to stretch the skin upon
the frame, larger or smaller skewers are employed, according as a
greater or smaller piece of it is to be laid hold of. Six holes are made
in a straight line to receive the larger, and four to receive the
smaller skewers or pins. These small slits are made with a tool like a
carpenter’s chisel, and of the exact size to admit the skewer. The
string round the skewer is affixed to one of the bolts in the frame,
which are turned round by means of a key, like that by which pianos and
harps are tuned. The skewer is threaded through the skin in a state of
tension.

Every thing being thus prepared, and the skin being well softened, the
workman stretches it powerfully by means of the skewers; he attaches the
cords to the skewers, and fixes their ends to the iron pegs or pins. He
then stretches the skin, first with his hand applied to the pins, and
afterwards with the key. Great care must be taken that no wrinkles are
formed. The skin is usually stretched more in length than in breadth,
from the custom of the trade; though extension in breadth would be
preferable, in order to reduce the thickness of the part opposite the
backbone.

The workman now takes the fleshing tool represented under CURRYING. It
is a semi-circular double-edged knife, made fast into a double wooden
handle. Other forms of the fleshing-knife edge are also used. They are
sharpened by a steel. The workman seizes the tool in his two hands, so
as to place the edge perpendicularly to the skin, and pressing it
carefully from above downwards, removes the fleshy excrescences, and
lays them aside for making glue. He now turns round the _herse_ upon the
wall, in order to get access to the outside of the skin, and to scrape
it with the tool inverted, so as to run no risk of cutting the
epidermis. He thus removes any adhering filth, and squeezes out some
water. The skin must next be ground. For this purpose it is sprinkled
upon the fleshy side with sifted chalk or slaked lime, and then rubbed
in all directions with a piece of pumice-stone, 4 or 5 inches in area,
previously flattened upon a sandstone. The lime gets soon moist from the
water contained in the skin. The pumice-stone is then rubbed over the
other side of the skin, but without chalk or lime. This operation is
necessary only for the best parchment or vellum. The skin is now allowed
to dry, upon the frame; being carefully protected from sunshine, and
from frost. In the arid weather of summer a moist cloth needs to be
applied to it from time to time, to prevent its drying too suddenly;
immediately after which the skewers require to be tightened.

When it is perfectly dry, the white colour is to be removed by rubbing
it with the woolly side of a lambskin. But great care must be taken not
to fray the surface; a circumstance of which some manufacturers are so
much afraid, as not to use either chalk or lime in the polishing. Should
any grease be detected upon it, it must be removed by steeping it in a
lime-pit for 10 days, then stretching it anew upon the _herse_, after
which it is transferred to the _scraper_.

This workman employs here an edge tool of the same shape as the
fleshing-knife, but larger and sharper. He mounts the skin upon a frame
like the _herse_ above described; but he extends it merely with cords,
without skewers or pins, and supports it generally upon a piece of raw
calfskin, strongly stretched. The tail of the skin being placed towards
the bottom of the frame, the workman first pares off, with a sharp
knife, any considerable roughnesses, and then scrapes the outside
surface obliquely downwards with the proper tools, till it becomes
perfectly smooth: the fleshy side needs no such operation; and indeed
were both sides scraped, the skin would be apt to become too thin, the
only object of the scraper being to equalize its thickness. Whatever
irregularities remain, may be removed with a piece of the finest
pumice-stone, well flattened beforehand upon a fine sandstone. This
process is performed by laying the rough parchment upon an oblong plank
of wood, in the form of a stool; the plank being covered with a piece of
soft parchment stuffed with wool, to form an elastic cushion for the
grinding operation. It is merely the outside surface that requires to be
pumiced. The celebrated Strasburgh vellum is prepared with remarkably
fine pumice-stones.

If any small holes happen to be made in the parchment, they must be
neatly patched, by cutting their edges thin, and pasting on small pieces
with gum water.

The skins for drum-heads, sieves, and battledores are prepared in the
same way. For drums, the skins of asses, calves, or wolves are employed;
the last being preferred. Ass skins are used for battledores. For
sieves, the skins of calves, she-goats, and, best of all, he-goats, are
employed. Church books are covered with the dressed skins of pigs.

Parchment is coloured only green. The following is the process. In 500
parts of rain water, boil 8 of cream of tartar, and 30 of crystallized
verdigris; when this solution is cold, pour into it 4 parts of nitric
acid. Moisten the parchment with a brush, and then apply the above
liquid evenly over its surface. Lastly, the necessary lustre may be
given with white of eggs, or mucilage of gum arabic.


PARTING (_Départ_, Fr.; _Scheidung_, Germ.), is the process by which
gold is separated from silver. See ASSAY, GOLD, REFINING, and SILVER.


PASTEL, is the French name of coloured crayons.


PASTEL, is a dye-stuff, allied to INDIGO, which see.


PASTES, or FACTITIOUS GEMS. (_Pierres précieuses artificielles_, Fr.;
_Glaspasten_, Germ.) The general vitreous body called Strass, (from the
name of its German inventor,) preferred by Fontanier in his treatise on
this subject, and which he styles the Mayence base, is prepared in the
following manner:--8 ounces of pure rock-crystal or flint in powder,
mixed with 24 ounces of salt of tartar, are to be baked and left to
cool. The mixture is to be afterwards poured into a basin of hot water,
and treated with dilute nitric acid till it ceases to effervesce; and
then the frit is to be washed till the water comes off tasteless. This
is to be dried, and mixed with 12 ounces of fine white-lead, and the
mixture is to be levigated and elutriated with a little distilled water.
An ounce of calcined borax being added to about 12 ounces of the
preceding mixture in a dry state, the whole is to be rubbed together in
a porcelain mortar, melted in a clean crucible, and poured out into cold
water. This vitreous matter must be dried, and melted a second and a
third time, always in a new crucible, and after each melting poured into
cold water, as at first, taking care to separate the lead that may be
revived. To the third frit, ground to powder, 5 drachms of nitre are to
be added; and the mixture being melted for the last time, a mass of
crystal will be found in the crucible, of a beautiful lustre. The
diamond may be well imitated by this Mayence base. Another very fine
white crystal may be obtained, according to M. Fontanier, from 8 ounces
of white-lead, 2 ounces of powdered borax, 1/2 grain of manganese, and 3
ounces of rock crystal, treated as above.

The colours of artificial gems are obtained from metallic oxides. The
_oriental topaz_, is prepared by adding oxide of antimony to the base;
the amethyst, by manganese with a little of the purple of Cassius; the
beryl, by antimony and a very little cobalt; yellow artificial diamond
and opal, by horn-silver (chloride of silver); blue-stone or sapphire,
by cobalt. The following proportions have been given:--

For the _yellow diamond_. To 1 ounce of strass add 24 grains of chloride
of silver, or 10 grains of glass of antimony.

For the _sapphire_. To 24 ounces of strass, add 2 drachms and 26 grains
of the oxide of cobalt.

For the _oriental ruby_. To 16 ounces of strass, add a mixture of 2
drachms, and 48 grains of the precipitate of Cassius, the same quantity
of peroxide of iron prepared by nitric acid, the same quantity of golden
sulphuret of antimony and of manganese calcined with nitre, and 2 ounces
of rock crystal. Manganese alone, combined with the base in proper
quantity, is said to give a ruby colour.

For the _emerald_. To 15 ounces of strass, add 1 drachm of mountain blue
(carbonate of copper), and 6 grains of glass of antimony; or, to 1 ounce
of base, add 20 grains of glass of antimony, and 3 grains of oxide of
cobalt.

For the _common opal_. To 1 ounce of strass, add 10 grains of
horn-silver, 2 grains of calcined magnetic ore, and 26 grains of an
absorbent earth (probably chalk-marl) _Fontanier_.

M. Douault-Wiéland, in an experimental memoir on the preparation of
artificial coloured stones, has offered the following instructions, as
being more exact than what were published before.

The base of all artificial stones is a colourless glass, which he calls
_fondant_, or flux; and he unites it to metallic oxides, in order to
produce the imitations. If it be worked alone on the lapidary’s wheel,
it counterfeits brilliants and rose diamonds remarkably well.

This base or strass is composed of silex, potash, borax, oxide of lead,
and sometimes arsenic. The siliceous matter should be perfectly pure;
and if obtained from sand, it ought to be calcined, and washed, first
with dilute muriatic acid, and then with water. The crystal or flint
should be made redhot, quenched in water, and ground, as in the
potteries. The potash should be purified from the best pearlash; and the
borax should be refined by one or two crystallizations. The oxide of
lead should be absolutely free from tin, for the least portion of this
latter metal causes milkiness. Good red-lead is preferable to litharge.
The arsenic should also be pure. Hessian crucibles are preferable to
those of porcelain, for they are not so apt to crack and run out. Either
a pottery or porcelain kiln will answer, and the fusion should be
continued 24 hours; for the more tranquil and continuous it is, the
denser is the paste, and the greater its beauty. The following four
recipes have afforded good strass:--

                                           Grains.
  No. I.

  Rock crystal                               4056
  Minium                                     6300
  Pure potash                                2154
  Borax                                       276
  Arsenic                                      12

  No. II.

  Sand                                       3600
  Ceruse of Clichy (pure carbonate of lead)  8508
  Potash                                     1260
  Borax                                       360
  Arsenic                                      12

  No. III.

  Rock crystal                               3456
  Minium                                     5328
  Potash                                     1944
  Borax                                       216
  Arsenic                                       6

  No. IV.

  Rock crystal                               3600
  Ceruse of Clichy                           8508
  Potash                                     1260
  Borax                                       360

                       _Topaz._            Grains.

    Very white paste                         1008
    Glass of antimony                          43
    Cassius purple                              1

  Or,

    Paste                                    3456
    Oxide of iron, called saffron of Mars      36

_Ruby._

M. Wiéland succeeded in obtaining excellent imitations of rubies, by
making use of the topaz materials. It often happened that the mixture
for topazes gave only an opaque mass, translucent at the edges, and in
thin plates of a red colour. 1 part of this substance being mixed with 8
parts of strass, and fused for 30 hours, gave a fine yellowish
crystal-like paste, and fragments of this fused before the blowpipe,
afforded the finest imitation of rubies. The result was always the same.

The following are other proportions for rubies:--

                                     Grains.
  Paste                                2880
  Oxide of manganese                     72

                   _Emerald._
  Paste                                4608
  Green oxide of pure copper             42
  Oxide of chrome                         2

                   _Sapphire._
  Paste                                4608
  Oxide of cobalt                        68

This mixture should be carefully fused in a luted Hessian crucible, and
be left 30 hours in the fire.

                  _Amethyst._
                                     Grains.
  Paste                                4608
  Oxide of manganese                     36
  Oxide of cobalt                        24
  Purple of Cassius                       1

   _Syrian Garnet, or Antient Carbuncle._
  Paste                                 512
  Glass of Antimony                     256
  Cassius purple                          2
  Oxide of manganese                      2

           _Beryl, or Aqua Marina._
  Paste                                3456
  Glass of antimony                      24
  Oxide of cobalt                         1-1/2

In all these mixtures, the substances should be mixed by sifting, fused
very carefully, and cooled very slowly, after having been left in the
fire from 24 to 30 hours.

M. Lançon has also made many experiments on the same subject. The
following are a few of his proportions:--

                   _Paste._
                                     Grains.
  Litharge                              100
  White sand                             75
  White tartar, or potash                10

                  _Amethyst._
  Paste                                9216
  Oxide of manganese          from 15 to 24
  Oxide of cobalt                         1

                  _Emerald._
  Paste                                9216
  Acetate of copper                      72
  Peroxide of iron, or saffron of Mars    1·5


PASTILLE, is the English name of small cones made of gum benzoin, with
powder of cinnamon, and other aromatics, which are burned as incense, to
diffuse a grateful odour, and conceal unpleasant smells in apartments.
See PERFUMERY.


PASTILLE, is the French name of certain aromatic sugared confections;
called also _tablettes_.


PEARLASH, a commercial form of POTASH, which see.


PEARLS (_Perles_, Fr.; _Perlen_, Germ.); are the productions of certain
shell-fish. These molluscæ are subject to a kind of disease caused by
the introduction of foreign bodies within their shells. In this case,
their pearly secretion, instead of being spread in layers upon the
inside of their habitation, is accumulated round these particles in
concentric layers. Pearl consists of carbonate of lime, interstratified
with animal membrane.

The oysters whose shells are richest in mother of pearl, are most
productive of these highly prized spherical concretions. The most
valuable pearl fisheries are on the coast of Ceylon, and at Olmutz in
the Persian Gulf, and their finest specimens are more highly prized in
the East than diamonds, but in Europe they are liable to be rated very
differently, according to the caprice of fashion. When the pearls are
large, truly spherical, reflecting and decomposing the light with much
vivacity, they are much admired. But one of the causes which renders
their value fluctuating, is the occasional loss of their peculiar
lustre, without our being able to assign a satisfactory reason for it.
Besides, they can be now so well imitated, that the artificial pearls
have nearly as rich an appearance as the real.


PEARLS, ARTIFICIAL. These are small globules or pear-shaped spheroids of
thin glass, perforated with two opposite holes, through which they are
strung, and mounted into necklaces, &c., like real pearl ornaments. They
must not only be white and brilliant, but exhibit the iridescent
reflections of mother of pearl. The liquor employed to imitate the
pearly lustre, is called the _essence of the east_ (_essence d’orient_),
which is prepared by throwing into water of ammonia the brilliant
scales, or rather the _lamellæ_, separated by washing and friction, of
the scales of a small river fish, the blay, called in French _ablette_.
These scales digested in ammonia, having acquired a degree of softness
and flexibility which allow of their application to the inner surfaces
of the glass globules, they are introduced by suction of the liquor
containing them in suspension. The ammonia is volatilized in the act of
drying the globules.

It is said that some manufacturers employ ammonia merely to prevent the
alteration of the scales; that when they wish to make use of them, they
suspend them in a well clarified solution of isinglass, then pour a drop
of the mixture into each bead, and spread it round the inner surface. It
is doubtful whether by this method, the same lustre and play of colours
can be obtained as by the former. It seems moreover to be of importance
for the success of the imitation, that the globules be formed of a
bluish, opalescent, very thin glass, containing but little potash and
oxide of lead. In every manufactory of artificial pearls, there must be
some workmen possessed of great experience and dexterity. The French are
supposed to excel in this ingenious branch of industry.


PEARLWHITE, is a submuriate of bismuth, obtained by pouring a solution
of the nitrate of that metal into a dilute solution of sea salt, whereby
a light and very white powder is obtained, which is to be well washed
and dried. See BISMUTH.


PECTIC ACID (_Acid pectique_, Fr.; _Gallertsaüre_, Germ.); so named on
account of its jellying property, from πηκτις, _coagulum_, exists in a
vast number of vegetables. The easiest way of preparing it, is to grate
the roots of carrots into a pulp, to express their juice, to wash the
_marc_ with rain or distilled water, and to squeeze it well; 50 parts of
the marc are next to be diffused through 300 of rain-water, adding by
slow degrees a solution of one part of pure potash, or two of
bicarbonate. This mixture is to be heated, so as to be made to boil for
about a quarter of an hour, and is then to be thrown boiling-hot upon a
filter cloth. It is known to have been well enough boiled, when a sample
of the filtered liquor becomes gelatinous by neutralizing it with an
acid. This liquor contains pectate of potassa, in addition to other
matters extricated from the root. The pectate may be decomposed by a
stronger acid, but it is better to decompose it by muriate of lime;
whereby a pectate of lime, in a gelatinous form, quite insoluble in
water, is obtained. This having been washed with cold water upon a
cloth, is to be boiled in water containing as much muriatic acid as will
saturate the lime. The pectic acid thus liberated, remains under the
form of a colourless jelly, which reddens litmus paper, and tastes sour,
even after it is entirely deprived of the muriatic acid. Cold water
dissolves very little of it; it is more soluble in boiling water. The
solution is colourless, does not coagulate on cooling, and hardly
reddens litmus paper; but it gelatinizes when alcohol, acids, alkalis,
or salts are added to it. Even sugar transforms it, after some time,
into a gelatinous state, a circumstance which serves to explain the
preparation of apple, cherry, raspberry, gooseberry, and other jellies.


PECTINE, or vegetable jelly, is obtained by mixing alcohol with the
juice of ripe currants, or any similar fruit, till a gelatinous
precipitate takes place; which is to be gently squeezed in a cloth,
washed with a little weak alcohol, and dried. Thus prepared, pectine is
insipid, without action upon litmus, in small pieces, semi-transparent,
and of a membranous aspect, like isinglass. Its mucilaginous solution in
cold water is not tinged blue with iodine. A very small addition of
potash, or its carbonate, converts pectine into pectic acid; both of
which substances are transformed into mucic and oxalic acids by the
nitric.


PELTRY (_Pelleterie_, Fr.; _Pelzwerk_, Germ.); is nearly synonymous with
fur, and comprehends the skins of different kinds of wild animals that
are found in high northern latitudes, particularly in the American
continent; such as the beaver, bear, moosedeer, marten, mink, sable,
woolverin, wolf, &c. When these skins have received no preparation but
from the hunters, they are most properly called peltry; but when they
have had the inner side tawed or tanned (see LEATHER) by an aluminous
process, they may then be denominated _furs_.

The scouring or cleaning of peltry is performed in a large cask, or
truncated cone laid on its side, and traversed by a revolving shaft,
which is furnished with a few rectangular rounded pegs. These are
intended to stir round the skins, while they are dusted over with Paris
plaster, whitening, or sometimes sand, made as hot as the hand can bear.
The bottom of the cask should be grated, to allow the impurities to fall
out. The _lustrage_, which the cleansed skins next undergo, is merely a
species of dyeing, either topical to modify certain disagreeable shades,
or general to impart a more beautiful colour to the fur. Under the
articles DYEING, and the several colours, as also HAIR and MOROCCO,
sufficient instructions will be found for dyeing fur. The mordants
should be applied pretty hot by a brush, on the hair of the skin,
stretched upon a solid table; and after two or three applications, with
drying between, the tinctorial infusions may be rubbed on in the same
way. The hair must be freed beforehand from all greasiness, by lime
water, or a weak solution of carbonate of soda; then well washed. Much
nicety, and many successive applications of the dye-stuff, are sometimes
requisite to bring out the desired shade.

Under HAT MANUFACTURE, I referred to this article for a description of
the process of _secrétage_, whereby the hairs of rabbit and hare skins
are rendered fit for felting. Dissolve 32 parts of quicksilver in 500 of
common aquafortis; and dilute the solution with one half or two thirds
of its bulk of water, according to the strength of the acid. The skin
being laid upon a table with the hair side uppermost, a brush, made with
the bristles of the wild boar, is to be slightly moistened with the
mercurial solution, and passed over the smooth surface of the hairs with
strong pressure. This application must be repeated several times in
succession, till every part of the fur be equally touched, and till
about two thirds of the length of the hairs be moistened, or a little
more, should they be rigid. In order to complete this impregnation, the
skins are laid together in pairs with the hairy sides in contact, put in
this state into the stove-room, and exposed to a heat higher in
proportion to the weakness of the mercurial solution. The drying should
be rapidly effected, otherwise the concentration of the nitrate will not
take due effect in causing the retraction and curling of the hairs.

No other acid, or metallic solution, but the above, has been found to
answer the desired purpose of the hatmaker. After the hairs are properly
_secreted_, they are plucked off by hand, or shorn off by a machine.


PENCIL MANUFACTURE. (_Crayons, fabrique de_, Fr.; _Bleistifte,
verfertigung_, Germ.) The word pencil is used in two senses. It
signifies either a small hair brush employed by painters in oil and
water colours, or a slender cylinder of black lead or plumbago, either
naked or enclosed in a wooden case, for drawing black lines upon paper.
The last sort, which is the one to be considered here, corresponds
nearly to the French term crayon, though this includes also pencils made
of differently coloured earthy compositions. See CRAYON.

The best black-lead pencils of this country are formed of slender
parallelopipeds, cut out by a saw from sound pieces of plumbago, which
have been previously calcined in close vessels at a bright red heat.
These parallelopipeds are generally enclosed in cases made of cedar
wood, though of late years they are also used alone, in peculiar
pencil-cases, under the name of ever-pointed pencils, provided with an
iron wire and screw, to protrude a minute portion of the plumbago beyond
the tubular metallic case, in proportion as it is wanted.

In the year 1795, M. Conté, a French gentleman, well acquainted with the
mechanical arts, invented an ingenious process for making artificial
black-lead pencils of superior quality, by which he and his successor
and son-in-law, M. Humblot, have realized large fortunes.

Pure clay, or clay containing the smallest proportion of calcareous or
siliceous matter, is the substance which he employed to give aggregation
and solidity, not only to plumbago dust, but to all sorts of coloured
powders. That earth has the property of diminishing in bulk, and
increasing in hardness, in exact proportion to the degree of heat it is
exposed to, and hence may be made to give every degree of solidity to
crayons. The clay is prepared by diffusing it in large tubs through
clear river water, and letting the thin mixture settle for two minutes.
The supernatant milky liquor is drawn off by a syphon from near the
surface, so that only the finest particles of clay are transferred into
the second tub, upon a lower level. The sediment which falls very slowly
in this tub, is extremely soft and plastic. The clear water being run
off, the deposit is placed upon a linen filter, and allowed to dry. It
is now ready for use.

The plumbago must be reduced to a fine powder in an iron mortar, then
put into a crucible, and calcined at a heat approaching to whiteness.
The action of the fire gives it a brilliancy and softness which it would
not otherwise possess, and prevents it from being affected by the clay,
which it is apt to be in its natural state. The less clay is mixed with
the plumbago, and the less the mixture is calcined, the softer are the
pencils made of it; the more clay is used the harder are the pencils.
Some of the best pencils made by M. Conté, were formed of two parts of
plumbago and three parts of clay; others of equal parts. This
composition admits of indefinite variations, both as to the shade and
hardness; advantages not possessed by the native mineral. While the
traces may be made as black as those of pure plumbago, they have not
that glistening aspect which often impairs the beauty of black-lead
drawings. The same lustre may, however, be obtained by increasing the
proportion of powdered plumbago relatively to the clay.

The materials having been carefully sifted, a little of the clay is to
be mixed with the plumbago, and the mixture is to be triturated with
water into a perfectly uniform paste. A portion of this paste may be
tested by calcination. If on cutting the indurated mass, particles of
plumbago appear, the whole must be further levigated. The remainder of
the clay is now to be introduced, and the paste is to be ground with a
muller upon a porphyry slab, till it be quite homogeneous, and of the
consistence of thin dough. It is now to be made into a ball, put upon a
support, and placed under a bell glass inverted in a basin of water, so
as to be exposed merely to the moist air.

Small grooves are to be made in a smooth board, similar to the pencil
parallelopipeds, but a little longer and wider, to allow for the
contraction of volume. The wood must be boiled in grease, to prevent the
paste from sticking to it. The above described paste being pressed with
a spatula into these grooves, another board, also boiled in grease, is
to be laid over them very closely, and secured by means of screw-clamps.
As the atmospheric air can get access only to the ends of the grooves,
the ends of the pencil-pieces become dry first, and by their contraction
in volume get loose in the grooves, allowing the air to insinuate
further, and to dry the remainder of the paste in succession. When the
whole piece is dried, it becomes loose, and might be turned out of the
grooves. But before this is done, the mould must be put into an oven
moderately heated, in order to render the pencil pieces still drier. The
mould should now be taken out, and emptied upon a table covered with
cloth. The greater part of the pieces will be entire, and only a few
will have been broken, if the above precautions have been duly observed.
They are all, however, perfectly straight, which is a matter of the
first importance.

In order to give solidity to these pencils, they must be set upright in
a crucible till it is filled with them, and then surrounded with
charcoal powder, fine sand, or sifted wood ashes. The crucible, after
having a luted cover applied, is to be put into a furnace, and exposed
to a degree of heat regulated by the pyrometer of Wedgewood; which
degree is proportional to the intended hardness of the pencils. When
they have been thus baked, the crucible is to be removed from the fire,
and allowed to cool with the pencils in it.

Should the pencils be intended for drawing architectural plans, or for
very fine lines, they must be immersed in melted wax or suet nearly
boiling hot, before they are put into the cedar cases. This immersion is
best done by heating the pencils first upon a gridiron, and then
plunging them into the melted wax or tallow. They acquire by this means
a certain degree of softness, are less apt to be abraded by use, and
preserve their points much better.

When these pencils are intended to draw ornamental subjects with much
shading, they should not be dipped as above.

_Second process for making artificial pencils, somewhat different from
the preceding._--All the operations are the same, except that some
lamp-black is introduced along with the plumbago powder and the clay. In
calcining these pencils in the crucible, the contact of air must be
carefully excluded, to prevent the lamp-black from being burned away on
the surface. An indefinite variety of pencils, of every possible black
tint, may thus be produced, admirably adapted to draw from nature.

Another ingenious form of mould is the following:

Models of the pencil-pieces must be made in iron, and stuck upright upon
an iron tray, having edges raised as high as the intended length of the
pencils. A metallic alloy is made of tin, lead, bismuth, and antimony,
which melts at a moderate heat. This is poured into the sheet-iron tray,
and after it is cooled and concreted, it is inverted, and shaken off
from the model bars, so as to form a mass of metal perforated throughout
with tubular cavities, corresponding to the intended pencil-pieces. The
paste is introduced by pressure into these cavities, and set aside to
dry slowly. When nearly dry, the pieces get so much shrunk that they may
be readily turned out of the moulds upon a cloth table. They are then to
be completely desiccated in the shade, afterwards in a stove-room, next
in the oven, and lastly ignited in the crucible, with the precautions
above prescribed.

M. Conté recommends the hardest pencils of the architect to be made of
lead melted with some antimony and a little quicksilver.

In their further researches upon this subject, M. Conté and M. Humblot
found that the different degrees of hardness of crayons could not be
obtained in a uniform manner by the mere mixture of plumbago and clay in
determinate doses. But they discovered a remedy for this defect in the
use of saline solutions, more or less concentrated, into which they
plunged the pencils, in order to modify their hardness, and increase the
uniformity of their texture. The non-deliquescent sulphates were
preferred for this purpose; such as sulphate of soda, &c. Even syrup was
found useful in this way.


PENS, STEEL. The best metal, made from Dannemora or hoop (L) iron, is
selected, and laminated into slips about 3 feet long, and 4 inches
broad, of a thickness corresponding to the desired stiffness and
flexibility of the pens. These slips are subjected to the action of a
stamping-press, somewhat similar to that for making buttons. (See
BUTTON, and PLATED WARE.) The point destined for the nib is next
introduced into an appropriate gauged hole of a little machine, and
pressed into the semi-cylindrical shape; where it is also pierced with
the middle slit, and the lateral ones, provided the latter are to be
given. The pens are now cleaned, by being tossed about among each other,
in a tin cylinder, about 3 feet long, and 9 inches in diameter; which is
suspended at each end upon joints, to two cranks, formed one on each of
two shafts. The cylinder, by the rotation of a flywheel, acting upon the
crank-shafts, is made to describe such revolutions as agitate the pens
in all directions, and polish them by mutual attrition. In the course of
4 hours several thousand pens may be finished upon this machine.


PEPPER. (_Poivre_, Fr.; _Pfeffer_, Germ.), Black pepper is composed,
according to M. Pelletier, of the vegetable principle, _piperine_, of a
very acrid concrete oil, a volatile balsamic oil, a coloured gummy
matter, an extractive principle analogous to legumine, malic and
tartaric acids, starch, bassorine, ligneous matter, with earthy and
alkaline salts in small quantity. Cubebs pepper has nearly the same
composition.

Pepper imported for home consumption,

  in      1835,      1836,       1837.--Duty 6_d._ per lb.
  Lbs.  2,359,573; 2,800,980; 2,626,298.


PERFUMERY, ART OF (_Parfumerie_, Fr.; _Wohlriechende-kunst_, Germ.);
consists in the preparation of different products, such as fats or
pommades, essential oils, distilled spirits, pastes, pastilles, and
essences.

Fats ought to be pounded in a marble mortar, without addition of water,
till all the membranes be completely torn; then subjected to the heat of
a water-bath in a proper vessel. The fat soon melts, and the albumen of
the blood coagulating, carries with it all the foreign substances; the
liquid matter should be skimmed, and passed through a canvas filter.

_Of pommades by infusion._--Rose, orange-flower, and cassia. Take 334
pounds of hog’s lard, and 166 of beef suet. These 500 pounds are put
into a pan called _bugadier_; and when melted, 150 pounds of rose-leaves
nicely plucked are added, taking care to stir the mixture every hour.
The infusion thus prepared is to remain at rest for 24 hours; at the end
of this time, the pommade is again melted, and well stirred to prevent
its adherence to the bottom of the melting-pan. The mass is now to be
poured out into canvas, and made into rectangular bricks or loaves,
which are subjected to a press, in order to separate the solid matter
from the soft pommade. These brick-shaped pieces being put into an
iron-bound barrel perforated all over its staves, the pommade is to be
allowed to exude on all sides, and flow down into a copper vessel placed
under the trough of the press. This manipulation should be repeated with
the same fat ten or twelve times; or in other words, 3000 pounds of
fresh rose-leaves should be employed to make a good pommade.

The pommade of orange-flowers is made in the same manner, as also the
pommade of cassia.

_Of pommades without infusion._--Jasmin, tuberose, jonquil, narcissus,
and violet.

A square frame, called _tiame_, is made of four pieces of wood, well
joined together, 2 or 3 inches deep, into which a pane of glass is laid,
resting upon inside ledges near the bottom. Upon the surface of the pane
the simple pommade of hog’s lard and suet is spread with a pallet knife;
and into this pommade the sweet-scented flowers are stuck fresh in
different points each successive day, during two or three months, till
the pommade has acquired the desired richness of perfume. The
above-described frames are piled closely over each other. Some
establishments at _Grasse_ possess from 3000 to 4000 of them.

_Of oils._--Rose, orange-flower, and cassia oils, are made by infusion,
like the pommades of the same perfumes; taking care to select oils
perfectly fresh. As to those of jasmin, tuberose, jonquil, violet, and
generally all delicate flowers, they are made in the following manner.
Upon an iron frame, a piece of cotton cloth is stretched, imbued with
olive oil of the first quality, and covered completely with a thin bed
of flowers. Another frame is similarly treated,--and in this way a pile
is made. The flowers must be renewed till the oil is saturated with
their odour. The pieces of cotton cloth are then carefully pressed to
extrude the oil. This last operation requires commonly 7 or 8 days.

_Of distillation._--The essential oils or essences, of which the great
manufacture is in the south of France, are of rose, neroli, lavender,
lemon thyme, common thyme, and rosemary. For the mode of distilling the
essential oils, see OILS, ESSENTIAL.

The essence of roses being obtained in a peculiar manner, I shall
describe it here. Put into the body of a still 40 pounds of roses, and
60 quarts of water; distil off one half of the water. When a
considerable quantity of such water of the first distillation is
obtained, it must be used as water upon fresh rose leaves; a process of
repetition to be carried to the fifth time. In the distillation of
orange-flower, to obtain the essence of neroli, the same process is to
be followed; but if orange-flower water merely be wanted, then it is
obtained at one distillation, by reserving the first fifth part of water
that comes over. What is called the essence of _petit-grain_, is
obtained by distilling the leaves of the orange shrub. The essences of
lavender, thyme, &c., present nothing peculiar in their mode of
extraction.

OF SCENTED SPIRITS,

From oil of rose, orange, jasmin, tuberose, cassia, violet, and other
flowers.

Into each of three digesters, immersed in water-baths, put 25 lbs. of
any one of these oils, and pour into the first digester 25 quarts of
spirit of wine; agitate every quarter of an hour during three days, and
at the end of this period, draw off the perfumed spirit, and pour it
into the second digester; then transfer it after 3 days into the third
digester, treating the mixture in the same way; and the spirit thus
obtained will be perfect. The digesters must be carefully covered during
the progress of these operations. On pursuing the same process with the
same oil and fresh alcohol, essences of inferior qualities may be
obtained, called Nos. 2, 3, and 4.

Some perfumers state that it is better to use highly scented pommades
than oils; but there is probably little difference in this respect.

_Esprit de suave._

  7 Eng. qrts. of spirit of jasmin, 3d operation.
  7         --            cassia,     --
  3         --            wine.
  2         --            tuberose,   --
  1-1/2 ounce essence of cloves.
  1/2 ounce fine neroli.
  1-1/2 ounce essence of bergamote.
  8 ounces essence of musk, 2d infusion.
  3 quarts rose water.

_Spirit of Cytherea._

  1 quart spirit of violets.
  1      --       jasmin, 2d operation.
  1      --       tuberose,    --
  1      --       clove gilly flower.
  1      --       roses, 2d operation.
  1      --       Portugal.
  2      --       orange-flower water.

_Spirit of flowers of Italy._

  2 quarts spirit of jasmin, 2d operation.
  2      --        roses       --
  2      --        oranges, 3d --
  2 quarts spirit of cassia, 2d operation.
  1-1/2  --        orange-flower water.

The above spirits mark usually 28 alcometric degrees of Gay Lussac. See
ALCOHOL.

POMMADES.

No less than 20 scented pommades are distinguished by the perfumers of
Paris. The essences commonly employed in the manufacture of pommades,
are those of bergamote, lemons, _cédrat_, _limette_ (sweet lemon),
Portugal, rosemary, thyme, lemon thyme, lavender, marjoram, and
cinnamon.

The following may serve as an example:--

_Pommade à la vanille_, commonly called Roman.

  12 pounds of pommade à la rose.
   3   --    oil à la rose.
   1   --    vanilla, first quality, pulverized.
   6 ounces    bergamote.

The pommade being melted at the heat of a water-bath, the vanilla is to
be introduced with continual stirring for an hour. The mixture is left
to settle during two hours. The pommade is then to be drawn off, and
will be found to have a fine yellow colour, instead of the brown shade
which it commonly has.

In making odoriferous extracts and waters, the spirits of the flowers
prepared by macerating the flowers in alcohol should be preferred to
their distillation, as forming the foundation of good perfumery. The
specific gravity of these spirits should be always under 0·88.

_Extract of nosegay (bouquet)._

  2 quarts spirit of jasmin, 1st operation.
  2  --  extract of violets.
  1  --  spirit of cassia, 1st   --
  1  --  roses,            1st   --
  1  --  orange,           1st   --
  1  --  extract of clove gilly flower.
  4 drms. of flowers of benzoin (benzoic acid).
  8 ounces of essence of amber, 1st infusion.

_Extract of peach blossoms._

  6 quarts of spirits of wine.
  6 pounds of bitter almonds.
  2 quarts of spirits of orange flower, 2d operation.
  4 drachms of essence of bitter almonds.
  4 drachms of balsam of Peru.
  4 ounces of essence of lemons.

_Eau de Cologne._

Two processes have been adopted for the preparation of this perfume,
distillation and infusion; the first of which, though generally
abandoned, is, however, the preferable one. The only essences which
should be employed, and which have given such celebrity to this water,
are the following; bergamote, lemon, rosemary, Portugal, neroli. The
whole of them ought to be of the best quality, but their proportions may
be varied according to the taste of the consumers.

Thirty different odours are enumerated by perfumers; the three following
recipes will form a sufficient specimen of their combinations.

_Honey-water._

  6 quarts of spirit of roses, 3d operation.
  3  do.                jasmin.
  3  do.                spirits of wine.
  3 ounces essence of Portugal.
  4 drachms flowers of benzoin.
  12 ounces of essence of vanilla, 3d infusion.
  12  do.                 musk,        do.
  3 quarts good orange-flower water.

_Eau de mille fleurs._

  18 quarts of spirits of wine.
  4 ounces balsam of Peru.
  8  do.   essence of bergamote.
  4  do.              cloves.
  1  do.   ordinary neroli.
  1  do.            thyme.
  8  do.            musk, 3d infusion
  4 quarts orange-flower water.

_Eau de mousseline._

  2 quarts spirit of roses,   3d infusion.
  2  do.             jasmin, 4th    do.
  1  do.             clove gilly flower.
  2  do.             orange flower, 4th do.
  2 ounces essence of vanilla, 3d infusion.
  2  do.              musk,        do.
  4 drachms of sanders wood.
  1 quart of orange-flower water.

_Almond pastes._

These are, gray, sweet white, and bitter white.

The first is made either with the kernels of apricots, or with bitter
almonds. They are winnowed, ground, and formed into loaves of 5 or 6
pounds weight, which are put into the press in order to extract their
oil; 300 pounds of almonds affording about 130 of oil. The pressure is
increased upon them every two hours during three days; at the end of
which time the loaves or cakes are taken out of the press to be dried,
ground, and sifted.

The second paste is obtained by boiling the almonds in water till their
skins are completely loosened; they are next put into a basket, washed
and blanched; then dried, and pressed as above.

The third paste is prepared like the second, only using bitter almonds.

_Liquid almond pastes_, such as those of the rose, orange, vanilla, and
nosegay.--The honey paste is most admired. It is prepared as follows:--

   6 pounds of honey.
   6  do.      white bitter paste.
  12 pounds oil of bitter almonds.
  26 yolks of eggs.

The honey should be heated apart and strained; 6 pounds of almond paste
must then be kneaded with it, adding towards the conclusion,
alternately, the quantity of yolks of eggs and almond oil indicated.

_Pastilles à la rose, orange flower, and vanilla._

_Pastilles à la rose._

           12 ounces of gum.
           12   do.     olibanum, in tears.
           12   do.     storax,      do.
            8   do.     nitre.
           16   do.     powder of pale roses.
  3 pounds 14   do.     charcoal powder.
            1   do.     essence of roses.

_Pastilles of orange flower._

  12 ounces of gum galbanum.
  12  do.      olibanum, in tears.
  12  do.      storax,      do.
   8  do.      nitre.
   1 pound of pure orange powder.
   3  do. 14 ounces charcoal powder.
   1 ounce superfine neroli.

_Pastilles à la vanille._

  12 ounces of gum galbanum.
  12  do.      olibanum, in tears.
  12  do.      storax       do.
   8  do.      nitre.
   8  do.      cloves.
  16 ounces powder of vanilla.
   3 pounds 14 ounces charcoal powder.
   4 drms. essence of cloves.
   8 ounces do. vanilla, 1st infusion.

The above mixture in each case is to be thickened with 2 ounces of gum
tragacanth dissolved in 2 pints of rose-water. It is needless to say
that the ingredients of the mixture should be impalpable powders.

_Scented cassolettes._

  8 pounds of black amber (ambergris).
  4  do.      rose powder.
  2 ounces of benzoin.
  1 ounce     essence of roses.
  1  do.      gum tragacanth.
  A few drops of the oil of sanders wood.

These ingredients are pulverized, and made into a cohesive paste with
the gum.

ESSENCES BY INFUSION.

_Essence of musk._

  5 ounces of musk from the bladder, cut small.
  1  do.      civet.
  4 quarts of spirit of ambrette (purple sweet sultan).

The whole are put into a matrass, and exposed to the sun for two months
during the hottest season of the year. In winter, the heat of a
water-bath must be resorted to.

_Essence of vanilla._

  3   pounds of vanilla in branches, 1st quality, cut small.
  4   quarts spirit of ambrette.
  2   drachms of cloves.
  1/2   do.      musk from the bladder.

The same process must be followed as for the essence of musk.

_Essence of ambergris._

  4 ounces of ambergris.
  2 ounces of bladder musk.
  8 quarts of spirit of ambrette.
  Treat as above.

_Spirit of ambrette_ (purple sweet sultan). 25 pounds of ambrette are to
be distilled with 25 quarts of spirits of wine, adding 12 quarts of
water, so as to be able to draw off the 25 quarts.


PERRY, is the fermented juice of pears, prepared in exactly the same way
as CYDER.


PERSIAN BERRIES. See BERRIES, PERSIAN.


PETROLEUM. See NAPHTHA.


PE-TUNT-SE, is the Chinese name of the fusible earthy matter of their
porcelain. It is analogous to our Cornish stone.


PEWTER, PEWTERER. _(Potier d’étain_, Fr.) Pewter is, generally speaking,
an alloy of tin and lead, sometimes with a little antimony or copper,
combined in several different proportions, according to the purposes
which the metal is to serve. The English tradesmen distinguish three
sorts, which they call plate, trifle, and ley pewter; the first and
hardest being used for plates and dishes; the second for beer-pots; and
the third for larger wine measures. The plate pewter has a bright
silvery lustre when polished; the best is composed of 100 parts of tin,
8 parts of antimony, 2 parts of bismuth, and 2 of copper. The trifle is
said by some to consist of 83 of tin, and 17 of antimony; but it
generally contains a good deal of lead. The ley pewter is composed of 4
of tin, and 1 of lead. As the tendency of the covetous pewterer is
always to put in as much of the cheap metal as is compatible with the
appearance of his metal in the market, and as an excess of lead may
cause it to act poisonously upon all vinegars and many wines, the French
government long ago appointed Fourcroy, Vauquelin, and other chemists,
to ascertain by experiment the proper proportions of a safe pewter
alloy. These commissioners found that 18 parts of lead might, without
danger of affecting wines, &c., be alloyed with 82 parts of tin; and the
French government in consequence passed a law, requiring pewterers to
use 83-1/2 of tin in 100 parts, with a tolerance of error amounting to
1-1/2 per cent. This ordonnance, allowing not more than 18 per cent. of
lead at a maximum, has been extended to all vessels destined to contain
alimentary substances. A table of specific gravities was also published,
on purpose to test the quality of the alloy; the density of which, at
the legal standard, is 7·764. Any excess of lead is immediately
indicated by an increase in the specific gravity above that number.

The pewterer fashions almost all his articles by casting them in moulds
of brass or bronze, which are made both inside and outside in various
pieces, nicely fitted together, and locked in their positions by ears
and catches or pins of various kinds. The moulds must be moderately
heated before the pewter is poured into them, and their surfaces should
be brushed evenly over with pounce powder (sandarach) beaten up with
white of egg. Sometimes a film of oil is preferred. The pieces, after
being cast, are turned and polished; and if any part needs soldering, it
must be done with a fusible alloy of tin, bismuth, and lead.

Britannia metal, the kind of pewter of which English tea-pots are made,
is said to be an alloy of equal parts of brass, tin, antimony, and
bismuth; but the proportions differ in different workshops, and much
more tin is commonly introduced. Queen’s metal is said to consist of 9
parts of tin, 1 of antimony, 1 of bismuth, and 1 of lead; it serves also
for teapots and other domestic utensils.

A much safer and better alloy for these purposes may be compounded by
adding to 100 parts of the French pewter, 5 parts of antimony, and 5 of
brass to harden it. The English ley pewter contains often much more than
20 per cent. of lead. Under TIN, will be found the description of an
easy method of analyzing its lead alloys.


PHOSPHORIC ACID, is the acid formed by the vivid combustion of


PHOSPHORUS. This interesting simple combustible, being an object of
extensive consumption, and therefore of a considerable chemical
manufacture, I shall describe the requisite manipulations for preparing
it at some detail. Put 1 cwt. of finely ground bone-ash, such as is used
by the assayers, into a stout tub, and let one person work it into a
thin pap with twice its weight of water, and let him continue to stir it
constantly with a wooden bar, while another person pours into it, in a
uniform but very slender stream, 78 pounds of concentrated sulphuric
acid.

The heat thus excited in the dilution of the acid, and in its reaction
upon the calcareous base, is favourable to the decomposition of the bone
phosphate. Should the resulting sulphate of lime become lumpy, it must
be reduced into a uniform paste, by the addition of a little water from
time to time. This mixture must be made out of doors, as under an open
shed, on account of the carbonic acid and other offensive gases which
are extricated. At the end of 24 hours, the pap maybe thinned with water
and, if convenient, heated, with careful stirring, to complete the
chemical change, in a square pan made of sheet lead, simply folded up at
the sides. Whenever the paste has lost its granular character, it is
ready for transfer into a series of tall casks, to be further diluted
and settled, whereby the clear superphosphate of lime may be run off by
a syphon from the deposit of gypsum. More water must then be mixed with
the precipitate, after subsidence of which, the supernatant liquor is
again to be drawn off. The skilful operator employs the weak acid from
one cask to wash the deposit in another, and thereby saves fuel in
evaporation.

The collected liquors being put into a leaden, or preferably a copper
pan, of proper dimensions, are to be concentrated by steady ebullition,
till the calcareous deposit becomes considerable; after the whole has
been allowed to cool, the clear liquor is to be run off, the sediment
removed, and thrown on a filter. The evaporation of the clear liquor is
to be urged till it acquires the consistence of honey. Being now
weighed, it should amount to 37 pounds. One fourth of its weight of
charcoal in fine powder, that is, about 9 pounds, are then to be
incorporated with it, and the mixture is to be evaporated to dryness in
a cast-iron pot. A good deal of sulphurous acid is disengaged along with
the steam at first, from the reaction of the sulphuric acid upon the
charcoal, and afterwards some sulphuretted hydrogen. When the mixture
has become perfectly dry, as shown by the redness of the bottom of the
pot, it is to be allowed to cool, and packed tight into stoneware jars
fitted with close covers, till it is to be subjected to distillation.
For this purpose, earthen retorts of the best quality, and free from
air-holes, must be taken, and evenly luted over their surface with a
compost of fire-clay and horse-dung. When the coating is dry and sound,
the retort is to be two-thirds filled with the powder, and placed upon
proper supports in the laboratory of an air-furnace, having its fire
placed not immediately beneath the retort, but to one side, after the
plan of a reverberatory; whereby the flame may play uniformly round the
retort, and the fuel may be supplied as it is wanted, without admitting
cold air to endanger its cracking. The gallery furnace of the palatinate
(under MERCURY) will show how several retorts may be operated upon
together, with one fire.

To the beak of the retort properly inclined, the one end of a bent
copper tube is to be tightly luted, while the other end is plunged not
more than one quarter of an inch beneath the surface of water contained
in a small copper or tin trough placed beneath, close to the side of the
furnace, or in a wide-mouthed bottle. It is of advantage to let the
water be somewhat warm, in order to prevent the concretion of the
phosphorus in the copper tube, and the consequent obstruction of the
passage. Should the beak of the retort appear to get filled with solid
phosphorus, a bent rod of iron may be heated, and passed up the copper
tube, without removing its end from the water. The heat of the furnace
should be most slowly raised at first, but afterwards equably maintained
in a state of bright ignition. After 3 or 4 hours of steady firing,
carbonic acid and sulphurous acid gases are evolved in considerable
abundance, provided the materials had not been well dried in the iron
pot; then sulphuretted hydrogen makes its appearance, and next
phosphuretted hydrogen, which last should continue during the whole of
the distillation.

The firing should be regulated by the escape of this remarkable gas,
which ought to be at the rate of about 2 bubbles per second. If the
discharge comes to be interrupted, it is to be ascribed either to the
temperature being too low, or to the retort getting cracked; and if upon
raising the heat sufficiently no bubbles appear, it is a proof that the
apparatus has become defective, and that it is needless to continue the
operation. In fact, the great nicety in distilling phosphorus lies in
the management of the fire, which must be incessantly watched, and fed
by the successive introduction of fuel, consisting of coke with a
mixture of dry wood and coal.

We may infer that the process approaches its conclusion by the
increasing slowness with which gas is disengaged under a powerful heat;
and when it ceases to come over, we may cease firing, taking care to
prevent reflux of water into the retort, from condensation of its
gaseous contents, by admitting air into it through a recurved glass
tube, or through the lute of the copper adopter.

The usual period of the operation upon the great scale is from 24 to 30
hours. Its theory is very obvious. The charcoal at an elevated
temperature disoxygenates the phosphoric acid with the production of
carbonic acid gas at first, and afterwards carbonic oxide gas, along
with sulphuretted, carburetted, and phosphuretted hydrogen, from the
reaction of the water present in the charcoal upon the other
ingredients.

The phosphorus falls down in drops, like melted wax, and concretes at
the bottom of the water in the receiver. It requires to be purified by
squeezing in a shamoy leather bag, while immersed under the surface of
warm water, contained in an earthen pan. Each bag must be firmly tied
into a ball form, of the size of the fist, and compressed, under the
water heated to 130°, by a pair of flat wooden pincers, like those with
which oranges are squeezed.

The purified phosphorus is moulded for sale into little cylinders, by
melting it at the bottom of a deep jar filled with water, then plunging
the wider end of a slightly tapering but straight glass tube into the
water, sucking this up to the top of the glass, so as to warm it, next
immersing the end in the liquid phosphorus, and sucking it up to any
desired height.

The tube being now shut at bottom by the application of the point of the
left index, may be taken from the mouth and transferred into a pan of
cold water to congeal the phosphorus; which then will commonly fall out
of itself, if the tube be nicely tapered, or may at any rate be pushed
out with a stiff wire. Were the glass tube not duly warmed before
sucking up the phosphorus, this would be apt to congeal at the sides,
before the middle be filled, and thus form hollow cylinders, very
troublesome and even dangerous to the makers of phosphoric
match-bottles. The moulded sticks of phosphorus are finally to be cut
with scissors under water to the requisite lengths, and put up in phials
of a proper size; which should be filled up with water, closed with
ground stoppers, and kept in a dark place. For carriage to a distance,
each phial should be wrapped in paper, and fitted into a tin-plate case.

Phosphorus has a pale yellow colour, is nearly transparent, brittle when
cold, soft and pliable, like wax, at the temperature of 70° F.,
crystallizing in rhombo-dodecahedrons out of its combination with
sulphur, and of specific gravity 1·77. It exhales white fumes in the
air, which have a garlic smell, appear luminous in the dark, and
spontaneously condense into liquid phosphorous acid. Phosphorus melts in
close vessels, at 95°. F., into an oily-looking colourless fluid, begins
to evaporate at 217·5°, boils at 554°, and if poured in the liquid state
into ice-cold water, it becomes black, but resumes its former colour
when again melted and slowly cooled. It has an acrid disagreeable taste,
and acts deleteriously in the stomach, though it has been administered
as a medicine by some of the poison-doctors of the present day. It takes
fire in the open air at the temperature of 165°, but at a lower degree
if partially oxidized, and burns with great vehemence and splendour.

Inflammable match-boxes (_briquets phosphoriques_) are usually prepared
by putting into a small phial of glass or lead a bit of phosphorus, and
oxidizing it slightly by stirring it round with a redhot iron wire. The
phial should be unstoppered only at the instant of plunging into it the
tip of the sulphur match which we wish to kindle. Bendix has given the
following recipe for charging such match-phials. Take one part of fine
dry cork raspings, one part of yellow wax, eight parts of petroleum, and
four of phosphorus, incorporate them by fusion, and when the mixture has
concreted by cooling, it is capable of kindling a sulphur match dipped
into it. Phosphorus dissolves in fat oils, forming a solution luminous
in the dark at ordinary temperatures. A phial half filled with this oil,
being shaken and suddenly uncorked, will give light enough to see the
dial of a watch by night.

There are five combinations, of phosphorus and oxygen:--1. the white
oxide; 2. the red oxide; 3. hypophosphorous acid; 4. phosphorous acid;
5. phosphoric acid. The last is the only one of interest in the arts. It
may be obtained from the syrupy superphosphate of lime above described,
by diluting it with water, saturating with carbonate of ammonia;
evaporating, crystallizing, and gently igniting the salt in a retort.
The ammonia is volatilized, and may be condensed into water by a
Woulfe’s apparatus, while the phosphoric acid remains in the bottom of
the retort. Phosphoric acid may be more readily produced by burning
successive bits of phosphorus in a silver saucer, under a great bell jar
inverted upon a glass plate, so as to admit a little air to carry on the
combustion. The acid is obtained in a fine white snowy deposit;
consisting, in this its dry state, of 44 of phosphorus and 56 of oxygen.
That obtained from the syrupy solution is a hydrate, and contains 9·44
per cent. of water. If the atom of phosphorus be called 32 upon the
hydrogen radix, then 5 atoms of oxygen = 40 will be associated with it
in the dry acid, = 72; and an additional atom of water = 9, in the
hydrate, will make its prime equivalent 81. Phosphorous acid seems to
contain no more than 3 atoms of oxygen.

The only salts of this acid much in demand, are the phosphate of soda,
and the ammonia phosphate of soda. The former is prepared by slightly
supersaturating superphosphate of lime with crystals of carbonate of
soda; warming the solution, filtering, evaporating, and crystallizing.
It is an excellent purgative, and not unpalatable. The triple phosphate
is used in docimastic operations; and is described under METALLURGY.


PICAMARE, is a thick oil, one of the six new principles detected by M.
Reichenbach, in wood-tar. See CREOSOTE and PARAFFINE. Picamare
constitutes 1-6th of beech-tar.


PICROMEL, is the name given by M. Thenard to a black bitter principle
which he supposed to be peculiar to the bile. MM. Gmelin and Tiedemann
have since called its identity in question.


PICROTOXINE, is an intensely bitter poisonous vegetable principle,
extracted from the seeds of the _Menispermum cocculus_, (Cocculus
Indicus). It crystallizes in small white needles, or columns; dissolves
in water and alcohol. It does not combine with acids, but with some
bases, and is not therefore of an alkaline nature, as had been at first
supposed.


PIGMENTS, VITRIFIABLE, belong to five different styles of work: 1. to
enamel painting; 2. to painting on metals; 3. to painting on stoneware;
4. to painting on porcelain; 5. to stained glass.


PIMENTO; _Myrtus pimenta_, or Jamaica pepper; consists, according to
Bonastre’s complicated analysis, of:--

  +--------------------------------+---------+--------+
  |                                |Shells or|Kernels.|
  |                                |Capsules.|        |
  +--------------------------------+---------+--------+
  |Volatile oil                    |  10·0   |   5·0  |
  |Soft green resin                |   8·0   |   2·5  |
  |Fatty concrete oil              |   0·9   |   1·2  |
  |Extract containing tannin       |  11·4   |  39·8  |
  |Gum                             |   3·0   |   7·2  |
  |Brown matter dissolved in potash|   4·0   |   8·0  |
  |Resinoid matter                 |   1·2   |   3·2  |
  |Extract containing sugar        |   3·0   |   8·0  |
  |Gallic and malic acids          |   0·6   |   1·6  |
  |Vegetable fibre                 |  50·0   |  16·0  |
  |Ashes charged with salts        |   2·8   |   1·9  |
  |Moisture and loss               |   4·1   |   4·8  |
  +--------------------------------+---------+--------+

  Pimento imported for home consumption, in           1835.      1836.
  Duty--British possessions, 5_d._; foreign,
  1_s._ 3_d._                                   Lbs. 344,458.   400,914.


PINCHBECK, is a modification of brass; see that article and COPPER.


PINE-APPLE YARN and CLOTH. In Mr. Zincke’s process, patented in
December, 1836, for preparing the filaments of this plant, the _Bromelia
ananas_, the leaves being plucked, and deprived of the prickles round
their edges by a cutting instrument, are then beaten upon a wooden block
with a wooden mallet, till a silky-looking mass of fibres be obtained,
which are to be freed by washing from the green fecula. The fibrous part
must next be laid straight, and passed between wooden rollers. The
leaves should be gathered between the time of their full maturity and
the ripening of the fruit. If earlier or latter, the fibres will not be
so flexible, and will need to be cleared by a boil in soapy water for
some hours; after being laid straight under the pressure of a wooden
grating, to prevent their becoming entangled. When well washed and
dried, with occasional shaking out, they will now appear of a silky
fineness. They may be then spun into porous rovings, in which state they
are most conveniently bleached by the ordinary methods.

Specimens of cambric, both bleached and unbleached, woven with these
fibres, have been recently exhibited, which excited hopes of their
rivalling the finest flax fabrics, but in my opinion without good
reason, on account of their want of strength.


PINEY TALLOW, is a concrete fat obtained by boiling with water the fruit
of the _Vateria indica_, a tree common upon the Malabar coast. It seems
to be a substance intermediate between tallow and wax; partaking of the
nature of stearine. It melts at 97-1/2° F., is white or yellowish, has a
spec. grav. of 0·926; is saponified by alkalies, and forms excellent
candles. Dr. Benjamin Babington, to whom we are indebted for all our
knowledge of piney tallow, found its ultimate constituents to be, 77 of
carbon, 12·3 of hydrogen, and 10·7 of oxygen.


PIN MANUFACTURE. (_Fabrique d’épingles_, Fr.; _Nadelfabrik_, Germ.) A
pin is a small bit of wire, commonly brass, with a point at one end, and
a spherical head at the other. In making this little article, there are
no less than fourteen distinct operations.

1. _Straightening the wire._ The wire, as obtained from the
drawing-frame, is wound about a bobbin or barrel, about 6 inches
diameter, which gives it a curvature that must be removed. The
straightening engine is formed by fixing 6 or 7 nails upright in a
waving line on a board, so that the void space measured in a straight
line between the first three nails may have exactly the thickness of the
wire to be trimmed; and that the other nails may make the wire take a
certain curve line, which must vary with its thickness. The workman
pulls the wire with pincers through among these nails, to the length of
about 30 feet, at a running draught; and after he cuts that off, he
returns for as much more; he can thus finish 600 fathoms in the hour. He
next cuts these long pieces into lengths of 3 or 4 pins. A day’s work of
one man amounts to 18 or 20 thousand dozen of pin-lengths.

2. _Pointing_, is executed on two iron or steel grindstones, by two
workmen, one of whom roughens down, and the other finishes. Thirty or
forty of the pin wires are applied to the grindstone at once, arranged
in one plane, between the two forefingers and thumbs of both hands,
which dexterously give them a rotatory movement.

3. _Cutting these wires into pin-lengths._ This is done by an adjusted
chisel. The intermediate portions are handed over to the _pointer_.

4. _Twisting of the wire for the pin-heads._ These are made of a much
finer wire, coiled into a compact spiral, round a wire of the size of
the pins, by means of a small lathe constructed for the purpose.

5. _Cutting the heads._ Two turns are dexterously cut off for each head,
by a regulated chisel, A skilful workman may turn off 12,000 in the
hour.

6. _Annealing the heads._ They are put into an iron ladle, made redhot
over an open fire, and then thrown into cold water.

7. _Stamping or shaping the heads._ This is done by the blow of a small
ram, raised by means of a pedal lever and a cord. The pin-heads are also
fixed on by the same operative, who makes about 1500 pins in the hour,
or from 12,000 to 15,000 per diem; exclusive of one-thirteenth, which is
always deducted for waste in this department, as well as in the rest of
the manufacture. Cast heads, of an alloy of tin and antimony, were
introduced by patent, but never came into general use.

8. _Yellowing or cleaning the pins_, is effected by boiling them for
half an hour in sour beer, wine lees, or solution of tartar; after which
they are washed.

9. _Whitening or tinning._ A stratum of about 6 pounds of pins is laid
in a copper pan, then a stratum of about 7 or 8 pounds of grain tin; and
so alternately till the vessel be filled; a pipe being left inserted at
one side, to permit the introduction of water slowly at the bottom,
without deranging the contents. When the pipe is withdrawn, its space is
filled up with grain tin. The vessel being now set on the fire, and the
water becoming hot, its surface is sprinkled with 4 ounces of cream of
tartar; after which it is allowed to boil for an hour. The pins and tin
grains are, lastly, separated by a kind of cullender.

10. _Washing the pins_, in pure water.

11. _Drying and polishing them_, in a leather sack filled with coarse
bran, which is agitated to and fro by two men.

12. _Winnowing_, by fanners.

13. _Pricking the papers_ for receiving the pins.

14. _Papering_, or fixing them in the paper. This is done by children,
who acquire the habit of putting up 36,000 per day.

The pin manufacture is one of the greatest prodigies of the division of
labour; it furnishes 12,000 articles for the sum of three shillings,
which have required the united diligence of fourteen skilful operatives.

The above is an outline of the mode of manufacturing pins by hand
labour, but several beautiful inventions have been employed to make them
entirely or in a great measure by machinery; the consumption for home
sale and export amounting to 15 millions daily, for this country alone.
One of the most elaborate and apparently complete, is that for which Mr.
L. W. Wright obtained a patent in May, 1824. A detailed description of
it will be found in the 9th volume of Newton’s London Journal. The
following outline will give my readers an idea of the structure of this
ingenious machine:--

The rotation of a principal shaft mounted with several cams, gives
motion to various sliders, levers, and wheels, which work the different
parts. A slider pushes pincers forwards, which draw wire from a reel, at
every rotation of the shaft, and advance such a length of wire as will
produce one pin. A dye cuts off the said length of wire by the descent
of its upper chap; the chap then opens a carrier, which takes the pin to
the pointing apparatus. Here it is received by a holder, which turns
round, while a bevel-edged file-wheel rapidly revolves, and tapers the
end of the wire to a point. The pin is now conducted by a second carrier
to a finer file-wheel, in order to finish the point by a second
grinding. A third carrier then transfers the pin to the first heading
die, and by the advance of a steel punch, the end of the pin wire is
forced into a recess, whereby the head is partially swelled out. A
fourth carrier removes the pin to a second die, where the heading is
perfected. When the heading-bar retires, a forked lever draws the
finished pin from the die, and drops it into a receptacle below.

I believe the chief objection to the raising of the heads by strong
mechanical compression upon the pins, is the necessity of softening the
wire previously; whereby the pins thus made, however beautiful to the
eye, are deficient in that stiffness which is so essential to their
employment in many operations of the toilet.


PIPERINE, is a crystalline principle extracted from black pepper, by
means of alcohol. It is colourless, has hardly any taste, fuses at 212°
F.; is insoluble in water, but soluble in acetic acid, ether, and most
readily in alcohol.


PITCH, MINERAL, is the same as BITUMEN and ASPHALT.


PITCH _of wood-tar_ (_Poix_, Fr.; _Pech_, Germ.); is obtained by boiling
tar in an open iron pot, or in a still, till the volatile matters be
driven off. Pitch contains, pyrolignous resin, along with colophany
(common rosin), but its principal ingredient is the former, called by
Berzelius pyretine. It is brittle in the cold, but softens and becomes
ductile with heat. It melts in boiling water, and dissolves in alcohol
and oil of turpentine, as well as in carbonated or caustic alkaline
lyes. For PYRETINE, see the mode of preparing it from birch wood, for
the purpose of preparing _Russia_ LEATHER.


PITCOAL. (_Houille_, Fr.; _Steinkohle_, Germ.) This is by far the most
valuable of mineral treasures, and the one which, at least in Great
Britain, makes all the others available to the use and comfort of man.
Hence it has been searched after with unremitting diligence, and worked
with all the lights of science, and the resources of art.

The Brora coal-field in Sutherlandshire is the most remarkable example
in this, or in perhaps any country hitherto investigated, of a pseudo
coal-basin among the deeper secondary strata, but above the new
sandstone or red marl formation. The Rev. Dr. Buckland and Mr. C. Lyell,
after visiting it in 1824, had expressed an opinion that the strata
there were wholly unconnected with the proper coal formation below the
new red sandstone, and were in fact the equivalent of the oolitic
series; an opinion fully confirmed by the subsequent researches of Mr.
Murchison. (_Geol. Trans._ for 1827, p. 293.) The Brora coal-field forms
a part of those secondary deposits which range along the south-east
coast of Sutherlandshire, occupying a narrow tract of about twenty miles
in length, and three in its greatest breadth.

One stratum of the Brora coal-pit is a coal-shale, composed of a
reed-like striated plant of the natural order _Equisetum_, which seems
to have contributed largely towards the formation of that variety of
coal. From this coal-shale, the next transition upwards is into a purer
bituminous substance approaching to _jet_, which constitutes the great
bed of coal. This is from 3 feet 3 inches to 3 feet 8 inches thick, and
is divided nearly in the middle by a thin layer of impure indurated
shale charged with pyrites, which, if not carefully excluded from the
mass, sometimes occasions spontaneous combustion upon exposure to the
atmosphere; and so much indeed is that mineral disseminated throughout
the district, that the shales might be generally termed “pyritiferous.”
Inattention on the part of the workmen, in 1817, in leaving a large
quantity of this pyritous matter to accumulate in the pit, occasioned a
spontaneous combustion, which was extinguished only by excluding the
air; indeed the coal-pit was closed in and remained unworked for four
years. The fires broke out again in the pit in 1827.

The purer part of the Brora coal resembles common pitcoal; but its
powder has the red ferruginous tinge of pulverized lignites. It may be
considered one of the last links between lignite and true coal,
approaching very nearly in character to jet, though less tenacious than
that mineral; and, when burnt, exhaling but slightly the vegetable odour
so peculiar to all imperfectly bituminized substances. The fossil
remains of shells and plants prove the Brora coal to be analogous to
that of the eastern moorlands of Yorkshire, although the extraordinary
thickness of the former, compared with any similar deposit of the latter
(which never exceeds from 12 to 17 inches), might have formerly led to
the belief that it was a detached and anomalous deposit of true coal,
rather than a lignite of any of the formations _above_ the new red
sandstone: such misconception might more easily arise in the infancy of
geology, when the strata were not identified by their fossil organic
remains.

On the coast of Yorkshire the strata of this pseudo coal formation
appear in the following descending order, from Filey Bay to Whitby. 1.
Coral-rag. 2. Calcareous grit. 3. Shale, with fossils of the Oxford
clay. 4. Kelloway rock (swelling out into an important arenaceous
formation). 5. Cornbrash. 6. Coaly grit of Smith. 7. Pier-stone
(according to Mr. Smith, the equivalent of the great oolite). 8.
Sandstone and shale, with _peculiar plants and various seams of coal_.
9. A bed with fossils of the inferior oolite. 10. Marl-stone? 11.
Alum-shale or lias. All the above strata are identified by abundant
organic remains.

In the oolitic series, therefore, where the several strata are developed
in conformity with the more ordinary type of these formations, we may
venture to predict with certainty, that no carboniferous deposits of any
great value will ever be discovered, at all events in Great Britain. A
want of such knowledge has induced many persons to make trials for coal
in beds subordinate to the English oolites, and even superior to them,
in places where the type of formation did not offer the least warrant
for such attempts.

The third great class of terrestrial strata, is the proper
coal-measures, called the _carboniferous rocks_, our leading object
here, and to which we shall presently return.

The transition rocks which lie beneath the coal-measures, and above the
primitive rocks, or are anterior to the carboniferous order, and
posterior to the primitive, contain a peculiar kind of coal, called
anthracite or stone-coal, approaching closely in its nature to carbon.
It is chiefly in the transition clay-slate that the anthracite occurs in
considerable masses. There is one in the transition slate of the little
Saint Bernard, near the village of _la Thuile_ (in the Alps). It is 100
feet long, and 2 or 3 yards thick. The coal burns with difficulty, and
is used only for burning lime. There are several of the same kind in
that country, which extend down the reverse slope of the mountains
looking to Savoy. The slate enclosing them presents vegetable
impressions of reeds or analogous plants. To the transition clay-slate
we must likewise refer the beds of anthracite that M. Hericart de Thury
observed at very great heights in the Alps of Dauphiny, in a formation
of schist and grey-wacke with vegetable impressions, which reposes
directly on the primitive rocks.

The great carboniferous formation may be subdivided into four orders of
rocks: 1. the coal-measures, including their manifold alternations of
coal-beds, sandstones, and shales; 2. the millstone grit and shale
towards the bottom of the coal-measures; 3. the carboniferous limestone,
which projecting to considerable heights above the outcrop of the coal
and grit, acquires the title of mountain limestone; 4. the old red
sandstone, or connecting link with the transition and primary rock basin
in which the coal system lies.

The coal-fields of England, from geographical position, naturally fall
under the following arrangement:--1. The _great northern district_;
including all the coal-fields north of Trent. 2. The _central district_;
including Leicester, Warwick, Stafford, and Shropshire. 3. The _western
district_; subdivided into _north-western_, including North Wales, and
the _south-western_, including South Wales, Gloucester, and
Somersetshire.

There are three principal coal-basins in Scotland: 1. that of Ayrshire;
2. that of Clydesdale; and 3. that of the valley of the Forth, which
runs into the second in the line of the Union Canal. If two lines be
drawn, one from Saint Andrews on the northeast coast, to Kilpatrick on
the Clyde, and another from Aberlady, in Haddingtonshire, to a point a
few miles south of Kirkoswald in Ayrshire, they will include between
them the whole space where pitcoal has been discovered and worked in
Scotland.

[Illustration: Mendip hills. Dundry hill. Wick rocks. Fog hill, N. of
Lansdowne.

794]

The great coal-series consists of a regular alternation of mineral
strata deposited in a great concavity or basin, the sides and bottom of
which are composed of transition rocks. This arrangement will be clearly
understood by inspecting _fig._ 794., which represents a section of the
coal-field south of Malmsbury.

1, 1, old red sandstone; 2, mountain limestone; 3, millstone grit; 4, 4,
coal seams; 5, Pennant, or coarse sandstone; 6, new red sandstone, or
red marl; 7, 7, lias; 8, 8, inferior oolite; 9, great oolite; 10,
cornbrash and Forest marble.

No. 1., or the old red sandstone, may therefore be regarded as the
characteristic lining of the coal basins; but this sandstone rests on
transition limestone, and this limestone on grey-wacke. This methodical
distribution of the carboniferous series is well exemplified in the
coal-basin of the Forest of Dean in the south-west of England, and has
been accurately described by Mr. Mushet.

The _grey-wacke_ consists of highly inclined beds of slaty micaceous
sandstone, which on the one hand alternates with and passes into a
coarse breccia, having grains as large as peas; on the other, into a
soft argillaceous slate. The grey-wacke stands bare on the north-eastern
border of the Forest, near the southern extremity of the chain of
transition limestone, which extends from Stoke Edith, near Hereford, to
Flaxley on the Severn. It is traversed by a defile, through which the
road from Gloucester to Ross winds. The abruptness of this pass gives it
a wild and mountainous character, and affords the best opportunity of
examining the varieties of the rock.

The _Transition limestone_ consists in its _lower beds_ of fine-grained,
tender, extremely argillaceous slate, known in the district by the name
of _water-stone_, in consequence of the wet soil that is found wherever
it appears at the surface. Calcareous matter is interspersed in it but
sparingly. Its _upper beds_ consist of shale alternating with extensive
beds of stratified limestone. The lowest of the calcareous strata are
thin, and alternate with shale. On these repose thicker strata of more
compact limestone, often of a dull blue colour. The beds are often
dolomitic, which is indicated by straw yellow colour, or dark pink
colour, and by the sandy or glimmering aspect of the rock.

The _old red sandstone_, whose limits are so restricted in other parts
of England, here occupies an extensive area. The space which it covers,
its great thickness, its high inclination, the abrupt character of the
surface over which it prevails, and the consequent display of its strata
in many natural sections, present in this strict advantages for studying
the formation, which are not to be met with elsewhere in South Britain.
In the neighbourhood of Mitchel Dean, the total thickness of this
formation, interposed conformably between the transition and mountain
limestone, is from 600 to 800 fathoms. The old red sandstone is
characterized in its upper portion by the presence of siliceous
conglomerate, containing siliceous pebbles, which is applied extensively
to the fabrication of millstones near Monmouth, and on the banks of the
Wye. This sandstone encircles the Forest with a ring of very elevated
ground, whose long and lofty ridges on the eastern frontier overhang the
valley of the Severn.

The _mountain limestone_, or carboniferous, is distinguished from
transition limestone, rather by its position than by any very wide
difference in its general character or organic remains. According to the
measurements of Mr. Mushet, the total thickness of the mountain
limestone is about 120 fathoms. The zone of limestone belonging to this
coal-basin, is from a furlong to a mile in breadth on the surface of the
ground, according as the dip of the strata is more or less rapid. The
angle of dip on the northern and western border is often no more than
10°, but on the eastern it frequently amounts to 80°. The calcareous
zone that defines the outer circle of the basin, suffers only one short
interruption, scarcely three miles in length, where in consequence of a
fault the limestone disappears, and the coal-measures are seen in
contact with the old red sandstone.

_Coal measures._--Their aggregate thickness amounts, according to Mr.
Mushet, to about 500 fathoms. 1. The lowest beds, which repose on the
mountain limestone, are about 40 fathoms thick, and consist here, as in
the Bristol coal-basin, of a red siliceous grit, alternating with
conglomerate, used for millstones; and with clay, occasionally used for
ochre. 2. These beds are succeeded by a series about 120 fathoms thick,
in which a grey gritstone predominates, alternating in the lower part
with shale, and containing 6 seams of coal. The grits are of a fissile
character, and are quarried extensively for flag-stone, ashlers, and
fire-stone. 3. A bed of grit, 25 fathoms thick, quarried for
hearth-stone, separates the preceding series from the following, or the
4th, which is about 115 fathoms thick, and consists of from 12 to 14
seams of coal alternating with shale. 5. To this succeeds a
straw-coloured sandstone, nearly 100 fathoms thick, forming a high ridge
in the interior of the basin. It contains several thin seams of coal,
from 6 to 16 inches in thickness. 6. On this reposes a series of about
12 fathoms thick, consisting of 3 seams of coal alternating with shale.
7. This is covered with alternate beds of grit and shale, whose
aggregate thickness is about 100 fathoms, occupying a tract in the
centre of the basin about 4 miles long, and 2 miles broad. The sandstone
No. 5. is probably the equivalent of the Pennant in the preceding
figure.

The floor, or pavement, immediately under the coal beds is, almost
without exception, a grayish-slate clay, which, when made into bricks,
strongly resists the fire. This fire-clay varies in thickness from a
fraction of an inch to several fathoms. Clay ironstone is often
disseminated through the shale.

[Illustration: 795 796 797]

The most complete and simplest form of a coal-field is the entire
basin-shape, which we find in some instances without a dislocation. A
beautiful example of this is to be seen at Blairengone, in the county of
Perth, immediately adjoining the western boundary of Clackmannanshire,
as represented in _fig._ 795., where the outer elliptical line, marked
A, B, C, D, represents the crop, outburst, or basset edge of the lower
coal, and the inner elliptical line represents the crop or basset edge
of the superior coal. _Fig._ 796. is the longitudinal section of the
line A B; and _fig._ 797. the transverse section of the line C D. All
the accompanying coal strata partake of the same form and parallelism.
These basins are generally elliptical, sometimes nearly circular, but
are often very eccentric, being much greater in length than in breadth;
and frequently one side of the basin on the short diameter has a much
greater dip than the other, which circumstance throws the trough or
lower part of the basin concavity much nearer to the one side than to
the other. From this view of one entire basin, it is evident that the
dip of the coal strata belonging to it runs in opposite directions, on
the opposite sides, and that all the strata regularly crop out, and meet
the alluvial cover in every point of the circumferential space, like the
edges of a nest of common basins. The waving line marks the river Devon.

[Illustration: 798 799 800]

It is from this basin shape that all the other coal-fields are formed,
which are segments of a basin produced by slips, dikes, or dislocations
of the strata. If the coals (_fig._ 795.) were dislocated by two slips
_b c_ and _d e_, the slip _b c_ throwing the strata _down_ to the east,
and the slip _d e_ throwing them as much _up_ in the same direction, the
outcrops of the coals would be found in the form represented in _fig._
798., of which _fig._ 799. is the section in the line A B, and _fig._
800. the section in the line C D.

The chief difficulty in exploring a country in search of coal, or one
where coal-fields are known to exist, arises from the great thickness of
alluvial and other cover, which completely hides the outcrop or basset
edge of the strata, called by miners the _rock-head_; as also the
fissures, dikes, and dislocations of the strata, which so entirely
change the structure and bearings of coal-fields, and cause often great
loss to the mining adventurer. The alluvial cover on the other hand is
beneficial, by protecting the seams of the strata from the superficial
waters and rains, which would be apt to drown them, if they were naked.
In all these figures of coal-basins, the letter _a_ indicates coal.

The absolute shape of the coal-fields in Great Britain has been
ascertained with surprising precision. To whatever depth a coal-mine is
drained of its water, from that depth it is worked, up to the rise of
the water-level line, and each miner continues to advance his room or
working-place, till his seam of coal meets the alluvial cover of the
outcrop, or is cut off by a dislocation of the strata. In this way the
miner travels in succession over every point of his field, and can
pourtray its basin-shape most minutely.

[Illustration: 801]

_Fig._ 801. represents a horizontal plan of the Clackmannanshire
coal-field, as if the strata at the outcrop all around were denuded of
the alluvial cover. Only two of the concentric beds, or of their edges
_a_, _a_, are represented, to avoid perplexity. It is to be remembered,
however, that all the series of attendant strata lie parallel to the
above lines. This plan shows the Ochill mountains, with the north
coal-fields, of an oblong elliptical shape, the side of the basin next
the mountains being precipitous, as if upheaved by the eruptive
trap-rocks; while the south, the east, and the west edges of the basin
shelve out at a great distance from the lower part of the concavity or
_trough_, as miners call it. Thus the alternate beds of coal, shale, and
sandstone, all nearly concentric in the north coal-field, dip inwards
from all sides towards the central area of the _trough_. The middle
coal-field of this district, however, which is formed by the great north
slip, is merely the segment of an elliptical basin, where the strata dip
in every direction to the middle of the axis marked with the letter X;
being the deepest part of the segment. The south coal-field, formed by
the great south slip, is likewise the segment of another elliptical
basin, similar in all respects to the middle coal-field. Beyond the
outcrop of the coals and subordinate strata of the south coal-fields,
the counter dip of the strata takes place, producing the mantle-shaped
form; whence the coal strata in the Dunmore field, in Stirlingshire, lie
in a direction contrary to those of the south coal-field of
Clackmannanshire. O, are the Ochill mountains.

[Illustration: 802]

_Fig._ 802. is intended to represent an extensive district of country,
containing a great coal-basin, divided into numerous subordinate
coal-fields by these dislocations. The lines marked _b_ are slips, or
faults; the broad lines marked _c_ denote dykes: the former dislocate
the strata, and change their level, while dykes disjoin the strata with
a wall, but do not in general affect their elevation. The two parallel
lines marked _a_, represent two seams of coal, variously heaved up and
down by the faults; whereas the dykes are seen to pass through the
strata without altering their relative position. In this manner, partial
coal-fields are distributed over a wide area of country, in every
direction.

[Illustration: 803]

The only exception to this general form of the coal-fields in Great
Britain, is the inverted basin shape; but this is rare. A few examples
occur in some districts of England, and in the county of Fife; but even
in extensive coal-fields, this convex form is but a partial occurrence,
or a deviation by local violence from the ordinary basin. _Fig._ 803 is
an instance of a convex coal-field exhibited in Staffordshire, at the
Castle-hill, close to the town of Dudley. 1, 1, are limestone strata; 2,
2, are coal. Through this hill, canals have been cut, for working the
immense beds of carboniferous limestone. These occur in the lower series
of the strata of the coal-field, and therefore at a distance of many
miles from the Castle-hill, beyond the outcrop of all the workable coals
in the proper basin-shaped part of the field; but by this apparently
inverted basin-form, these limestone beds are elevated far above the
level of the general surface of the country, and consequently above the
level of all the coals. We must regard this seeming inversion as
resulting from the approximation of two coal-basins, separated by the
basset edges of their mountain limestone repository.

[Illustration: 804 807]

_Fig._ 804. is a vertical section of the Dudley coal-basin, the upper
coal-bed of which has the astonishing thickness of 30 feet; and this
mass extends 7 miles in length, and 4 in breadth. Coal-seams 5 or 6 feet
thick, are called _thin_ in that district.

[Illustration: 805]

_Fig._ 805. is a very interesting section of the main coal-basin of
Clackmannanshire, as given by Mr. Bald in the Wernerian Society’s
Memoirs, vol. iii. Here we see it broken into three subordinate
coal-fields, formed by two great faults or dislocations of the strata;
but independently of these fractures across the whole series, the strata
continue quite regular in their respective alternations, and preserve
nearly unchanged their angle of inclination to the horizon. The section
shows the south coal-field dipping northerly, till it is cut across by
the great south slip _x_, which dislocates the coal and the parallel
strata to the enormous extent of 1230 feet, by which all the coals have
been thrown up, not simply to the day, but are not found again till we
advance nearly a mile northward, on the line of the dip, where the
identical seams of coal, shale, &c. are observed once more with their
regular inclination. These coals of the middle area, dip regularly
northward till interrupted by the great north slip _y_, which dislocates
the strata, and throws them up 700 feet; that is to say, a line
prolonged in the direction of any one well-known seam, will run 700 feet
above the line of the same seam as it emerges after the middle slip.
Immediately adjoining the north slip, the coals and coal-field resume
their course, and dip regularly northward, running through a longer
range than either of the other two members of the basin, till they
arrive at the valley of the Devon, at the foot of the Ochill mountains,
where they form a concave curvature, or trough, _a_, and thence rise
rapidly in an almost vertical direction at _b_. Here the coals, with all
their associate strata, assume conformity and parallelism with the face
of the sienitic-greenstone strata of the Ochill mountains _c_; being
raised to the high angle of 73 degrees with the horizon. The coal-seams
thus upheaved, are called _edge-metals_ by the miners.

[Illustration: 806]

In this remarkable coal-field, which has been accurately explored by
pitting and boring to the depth of 703 feet, there are no fewer than 142
beds, or distinct strata of coal, shale, and sandstone, &c., variously
alternating, an idea of which may be had by inspecting _fig._ 806. Among
these are 24 beds of coal, which would constitute an aggregate thickness
of 59 feet 4 inches; the thinnest seam of coal being 2 inches, and the
thickest 9 feet. The strata of this section contain numerous varieties
of sandstone, slate-clay, bituminous shale, indurated clay, or
fire-clay, and clay ironstone. Neither trap-rock nor limestone is found
in connexion with the workable coals; but an immense bed of greenstone,
named Abbey Craig, occurs in the western boundary of Clackmannanshire,
under which lie regular strata of slate-clay, sandstone, thin beds of
limestone, and large spheroidal masses of clay ironstone, with a mixture
of lime.

“With regard to slips in coal fields,” says Mr. Bald, “we find that
there is a general law connected with them as to the position of the
dislocated strata, which is this:--When a slip is met with in the course
of working the mines--if when looking to it, the vertical line of the
slip or fissure, it forms an acute angle with the line of the pavement
upon which the observer stands, we are certain that the strata are
dislocated downwards upon the other side of the fissure. On the
contrary, if the angle formed by the two lines above mentioned is
obtuse, we are certain that the strata are dislocated or thrown upwards
upon the other side of the fissure. When the angle is 90°, or a right
angle, it is altogether uncertain whether the dislocation throws up or
down on the opposite side of the slip. When dikes intercept the strata,
they generally only separate the strata the width of the dike, without
any dislocation, either up or down; so that if a coal is intercepted by
a dike, it is found again by running a mine directly forward,
corresponding to the angle or inclination of the coal with the
horizon.”--_Wernerian Society’s Memoirs_, vol. iii. p. 133.[40]

  [40] This paper does honour to its author, the eminent coal-viewer of
  Scotland.

[Illustration: 808

  _a._ Alluvial cover.
  _b._ Bed of trap or greenstone.
  _c._ Alternating coal strata.
  _d._ Coal-seams.
  _e._ Position of greenstone, not ascertained.
  _f._ Strata in which no coals have been found.
  _g._ The overlapped coal.
  _h._ The double coal.]

The Johnstone coal-field, in Renfrewshire, is both singular and
interesting. The upper stratum of rock is a mass of compact greenstone
or trap, above 100 feet in thickness, not at all in a conformable
position with the coal strata, but overlying; next there is a few
fathoms of soft sandstone and slate-clay, alternating, and uncommonly
soft. Beneath these beds, there are no fewer than ten seams of coal,
lying on each other, with a few divisions of dark indurated clay. These
coal-seams have an aggregate thickness of no less than 100 feet; a mass
of combustible matter, in the form of coal, unparalleled for its
accumulation in so narrow a space. The greater part of this field
contains only 5 beds of coal; but at the place where the section shown
in _fig._ 807. is taken, these 5 coals seem to have been overlapped or
made to slide over each other by violence. This structure is represented
in _fig._ 808., which is a section of the Quarrelton coal in the
Johnstone field, showing the overlapped coal and the double coal, with
the thick bed of greenstone, overlying the coal-field.

Before proceeding to examine the modes of working coal, I shall
introduce here a description of the two principal species of this
mineral.

1. _Cubical coal._--It is black, shining, compact, moderately hard, but
easily frangible. When extracted in the mine, it comes out in
rectangular masses, of which the smaller fragments are cubical. The
lamellæ (_reed_ of the coal) are always parallel to the bed or plane on
which the coal rests; a fact which holds generally with this substance.
There are two varieties of cubical coal; the _open-burning_ and the
_caking_. The latter, however small its fragments may be, is quite
available for fuel, in consequence of its agglutinating into a mass at a
moderate heat, by the abundance of its bitumen. This kind is the true
smithy or forge-coal, because it readily forms itself into a vault round
the blast of the bellows, which serves for a cupola in concentrating the
heat on objects thrust into the cavity.

The open-burning cubical coals are known by several local names; the
rough coal or clod coal, from the large masses in which they may be
had; and the cherry coal, from the cheerful blaze with which they
spontaneously burn; whereas the caking coals, such as most of the
Newcastle qualities, require to be frequently poked in the grate. Its
specific gravity varies from 1·25 to 1·4.

2. _Slate or splint coal._--This is dull-black, very compact, much
harder, and more difficultly frangible than the preceding. It is readily
fissile, like slate, but powerfully resists the cross fracture, which is
conchoidal. Specific gravity from 1·26 to 1·40. In working, it separates
in large quadrangular sharp-edged masses. It burns without caking,
produces much flame and smoke, unless judiciously supplied with air, and
leaves frequently a considerable bulk of white ashes. It is the best
fuel for distilleries and all large grates, as it makes an open fire,
and does not clog up the bars with glassy scoriæ. I found good splint
coal of the Glasgow field to have a specific gravity of 1·266, and to
consist of--carbon, 70·9; hydrogen, 4·3; oxygen, 24·8.

3. _Cannel coal._--Colour between velvet and grayish-black; lustre
resinous; fracture even; fragments trapezoidal; hard as splint coal;
spec. grav. 1·23 to 1·28. In working, it is detached in four-sided
columnar masses, often breaks conchoidal, like pitch, kindles very
readily, and burns with a bright white projective flame, like the wick
of a candle, whence its name. It occurs most abundantly in the
coal-field of Wigan, in Lancashire, in a bed 4 feet thick; and there is
a good deal of it in the Clydesdale coal-field, of which it forms the
lowest seam that is worked. It produces very little dust in the mine,
and hardly soils the fingers with carbonaceous matter. Cannel coal from
Woodhall, near Glasgow, spec. grav. 1·228, consists by my analysis
of--carbon, 72·22; hydrogen, 3·93; oxygen, 21·05; with a little azote
(about 2·8 in 100 parts). This coal has been found to afford, in the
Scotch gas-works, a very rich-burning gas. The azote is there converted
into ammonia, of which a considerable quantity is distilled over into
the tar-pit.

4. _Glance coal._--This species has an iron-black colour, with an
occasional iridescence, like that of tempered steel; lustre in general
splendent, shining, and imperfect metallic; does not soil; easily
frangible; fracture flat conchoidal; fragments sharp-edged. It burns
without flame or smell, except when it is sulphureous; and it leaves a
white-coloured ash. It produces no soot, and seems, indeed, to be merely
carbon, or coal deprived of its volatile matter or bitumen, and
converted into coke by subterranean calcination, frequently from contact
with whin-dikes. Glance coal abounds in Ireland, under the name of
Kilkenny coal; in Scotland it is called blind coal, from its burning
without flame or smoke; and in Wales, it is the malting or stone coal.
It contains from 90 to 97 per cent. of carbon. Specific gravity from 1·3
to 1·5; increasing with the proportion of earthy impurities.

The dislocations and obstructions found in coal-fields, which render the
search for coal so difficult, and their mining so laborious and
uncertain, are the following:--

1. _Dikes._ 2. _Slips or Faults._ 3. _Hitches._ 4. _Troubles._

The first three infer dislocation of the strata; the fourth changes in
the bed of coal itself.

1. A dike is a wall of extraneous matter, which divides all the beds in
a coal-field.

[Illustration: 809]

Dikes extend not only in one line of bearing through coal-fields for
many miles, but run sometimes in different directions, and have often
irregular bendings, but no sharp angular turns. When from a few feet to
a few fathoms in thickness, they occur sometimes in numbers within a
small area of a coal basin, running in various directions, and even
crossing each other. _Fig._ 809. represents a ground plan of a
coal-field, intersected with greenstone dikes. A B and C D are two dikes
standing parallel to each other; E F and G H are cross or oblique dikes,
which divide both the coal strata and the primary dikes A B and C D.

[Illustration: 810 811]

2. _Slips_ or _faults_ run in straight lines through coal-measures, and
at every angle of incidence to each other. _Fig._ 810. represents a
ground plan of a coal-field, with two slips A B and C D in the line of
bearing of the planes of the strata, which throw them down to the
outcrop. This is the simplest form of a slip. _Fig._ 811. exhibits part
of a coal-field intersected with slips, like a cracked sheet of ice.
Here A B is a dike; while the narrow lines show faults of every kind,
producing dislocations varying in amount of slip from a few feet to a
great many fathoms. The faults at the points _a_, _a_, _a_ vanish; and
the lines at _c_ denote four small partial slips called _hitches_.

[Illustration: 812]

The effects of slips and dikes on the coal strata appear more
prominently when viewed in a vertical section, than in a ground plan,
where they seem to be merely walls, veins, and lines of demarcation.
_Fig._ 812. is a vertical section of a coal-field, from dip to rise,
showing three strata of coal _a_, _b_, _c_. A B represents a dike at
right angles to the plane of the coal-beds. This rectangular wall merely
separates the coal-measures, affecting their line of rise; but further
to the rise, the oblique dike C D interrupts the coals _a_, _b_, _c_,
and not only disjoins them, but throws them and their concomitant strata
greatly lower down; but still, with this depression, the strata retain
their parallelism and general slope. Nearer to the outcrop, another dike
E, F, interrupts the coals _a_, _b_, _c_, not merely breaking the
continuity of the planes, but throwing them moderately up, so as to
produce a steeper inclination, as shown in the figure. It sometimes
happens that the coals in the compartment H, betwixt the dikes C and E,
may lie nearly horizontal, and the effect of the dike E, F, is then to
throw out the coals altogether, leaving no vestige of them in the
compartment K. “Such,” says Mr. Bald, from whom these illustrations are
borrowed, “are the most prominent changes in the strata, as to their
line of direction, produced by dikes; but of these changes there are
various modifications.”

[Illustration: 813]

The effect of slips on the strata is also represented in the vertical
section, _fig._ 813., where _a_, _b_, _c_ are coals with their
associated strata. A, B, is an intersecting slip, which throws all the
coals of the first compartment much lower, as is observable in the
second, No. 2.; and from the amount of the slip, it brings in other
coal-seams, marked 1, 2, 3, not in the compartment No. 1. C, D, is a
slip producing a similar result, but not of the same magnitude. E, F,
represents a slip across the strata, reverse in direction to the former;
the effect of which is to throw up the coals, as shown in the area No.
4. Such a slip occasionally brings into play seams seated under those
marked _a_, _b_, _c_, as seen at 4, 5, 6; and it may happen that the
coal marked 4 lies in the prolongation of a well-known seam, as _c_, in
the compartment No. 3., when the case becomes puzzling to the miner. In
addition to the above varieties, a number of slips or hitches are often
seen near one another, as in the area marked No. 5., where the
individual displacements are inconsiderable, but the aggregate
dislocation may be great, in reference to the seams of the 6th
compartment.

[Illustration: 814]

The results of dikes and slips on a horizontal portion of a field are
exemplified in _fig._ 814. Where the coal-measures are horizontal, and
the faults run at a greater angle than 45° to the line of bearing, they
are termed dip and rise faults, as A B, C D, E F.

[Illustration: 815]

Coal viewers or engineers regard the dislocations now described as being
subject in one respect to a general law, which may be thus
explained:--Let _fig._ 815. be a portion of a coal-measure; A, being
the pavement and B the roof of the coal-seam. If, in pursuing the
stratum at C, a dike D occurs, standing at right angles with the
pavement, they conclude that the dike is merely a partition-wall between
the beds by its own thickness, leaving the coal-seam underanged on
either side; but if a dike F forms, as at E, an obtuse angle with the
pavement, they conclude that the dike is not a simple partition between
the strata, but has thrown up the several seams into the predicament
shown at G. Finally, should a dike H make at I an acute angle with the
pavement, they conclude that the dike has thrown down the coal-measures
into the position of K.

The same important law holds with slips, as I formerly stated; only when
they form right angles with the pavement, the case is ambiguous; that
is, the strata may be dislocated either upwards or downwards.

Dikes and faults are denominated upthrow or downthrow, according to the
position they are met with in working the mine. Thus, in _fig._ 812., if
the miner is advancing to the rise, the dike A, B obviously does not
change the direction; but C, D is a downthrow dike of a certain number
of fathoms towards the rise of the basin, and E, F is an upthrow dike
likewise towards the rise. On the other hand, when the dikes are met
with by the miner in working from the rise to the dip, the names of the
above dikes would be reversed; for what is an upthrow in the first case,
becomes a downthrow in the second, relative to the mining operations.

[Illustration: 816]

3. We have seen that _hitches_ are small and partial slips, where the
dislocation does not exceed the thickness of the coal-seam; and they are
correctly enough called _steps_ by the miner. _Fig._ 816. represents the
operation of the _hitches_ A, B, C, D, E, F, G, H, on the coal-measures.
Though observed in one or two seams of a field, they may not appear in
the rest, as is the case with dikes and faults.

4. _Troubles_ in coal-fields are of various kinds.

1. _Irregular layers of sandstone_, appearing in the middle of the
coal-seam, and gradually increasing in thickness till they separate the
coal into two distinct seams, too thin to continue workable.

[Illustration: 817 818]

2. _Nips_, occasioned by the gradual approximation of the roof and
pavement, till not a vestige of coal is left between them; the softer
shale disappearing also at the same time. _Figs._ 817. and 818.
represent this accident, which is fortunately rare; the first being a
vertical, and the second a horizontal view.

3. _Shaken coal._ It resembles the rubbish of an old waste, being a
confused heap of coal-dust, mixed with small pieces of cubical coal, so
soft that it can frequently be dug with the spade. This shattering is
analogous to that observed occasionally in the flint nodules of the
chalk formation; and seems like the effect of some electric tremor of
the strata.

In searching for coal in any country, its concomitant rocks ought to be
looked for, especially the carboniferous or mountain limestone, known by
its organic fossils; (see Ure’s Geology, p. 175, and corresponding plate
of fossils;) likewise the outcrop of the millstone grit, and the newer
red sandstone, among some rifts or façades of which, seams of coal may
be discerned. But no assurance of coal can be had without boring or
pitting.

Skill in boring judiciously for coal, distinguishes the genuine miner
from the empirical adventurer, who, ignorant of the general structure of
coal-basins, expends labour, time, and money at random, and usually to
no purpose; missing the proper coal-field, and leading his employer to
sink a shaft where no productive seams can be had. A skilful viewer,
therefore, should always direct the boring operations, especially in an
unexplored country.

The boring rods should be made of the best and most tenacious Swedish
iron; in area, about an inch and a quarter square. Each rod is usually 3
feet long, terminating in a male screw at one end, and a female screw at
the other. The boring chisels are commonly 18 inches long, and from 2
inches and a half to 3 inches and a quarter at their cutting edge, which
must be tipped with good steel. The chisel is screwed to an intermediate
18-inch rod, called the double box-rod, forming together a rod 3 feet
long. There are, moreover, three short rods, a foot, 18 inches, and 2
feet long each, which may be screwed, as occasion requires, to the
brace-head, to make the height above the mouth of the bore convenient
for the hands of the men in working the rods. Hence the series of rods
becomes a scale of measurement for noting the depth of the bore, and
keeping a journal of the strata that are perforated. The brace-head rod,
also 18 inches long, has two large eyes or rings at its top, set at
right angles to each other, through which arms of wood are fixed for the
men to lift and turn the rods by, in the boring process.

When the bore is intended to penetrate but a few fathoms, the whole work
may be performed directly by the hands; but when the bore is to be of
considerable depth, a lofty triangle of wood is set above the bore-hole,
with a pulley depending at its summit angle, for conducting the rope to
the barrel of a windlass or wheel and axle, secured to the ground with
heavy stones. The loose end of the rope is connected to the rods by an
oval iron ring, called a runner; and by this mechanism they may be
raised and let fall in the boring; or the same effect may be more simply
produced by substituting for the wheel and axle, a number of ropes
attached to the rod-rope, each of which may be pulled by a man, as in
raising the ram of the pile-engine.

In the Newcastle coal district there are professional master-borers, who
undertake to search for coal, and furnish an accurate register of the
strata perforated. The average price of boring in England or Scotland,
where no uncommon difficulties occur, is six shillings for each of the
first five fathoms, twice 6 shillings for each of the second five
fathoms, thrice 6 shillings for each of the third five fathoms, and so
on; hence the series will be--

  1st five fathoms       6_s._ each     _£_1 10
  2nd five fathoms      12_s._  --         3  0
  3rd five fathoms      18_s._  --         4 10
  4th five fathoms      24_s._  --         6  0
  --                    ------         --------
  20 fathoms of bore                   _£_15  0

Thus the price increases equably with the depth and labour of the bore,
and the undertaker usually upholds his rods. There are peculiar cases,
however, in which the expense greatly exceeds the above rate.

The boring tools are represented in the following figures:--

[Illustration: 819

_Fig._ 819.

   1. The _brace-head_.
   2. The common rod.
   3. The double-box rod; intermediate piece.
   4. The common chisel.
   5. The indented chisel.
   6. Another of the same.
   7. The cross-mouthed chisel.
   8. The wimble.
   9. The sludger, for bringing up the mud.
  10. The rounder.
  11. The key for supporting the train of rods at the bore-mouth.
  12. The key for screwing together and asunder the rods.
  13. The topit, or top-piece.
  14. The beché, for catching the rod when it breaks in the bore.
  15. The runner, for taking hold of the topit.
  16. The tongued chisel.
  17. The right-handed worm screw.
  18. The left-handed do.
  19. The finger-grip or catch.]

We shall now explain the manner of conducting a series of bores in
searching ground for coal.

[Illustration: 820]

_Fig._ 820. represents a district of country in which a regular survey
has proved the existence and general distribution of coal strata, with a
dip to the south, as here shown. In this case, a convenient spot should
be pitched upon in the north part of the district, so that the
successive bores put down may advance in the line of the dip. The first
bore may therefore be made at No. 1., to the depth of sixty yards. In
the progress of this perforation, many diversities and alternations of
strata will be probably passed through, as we see in the sections of the
strata; each of which, as to quality and thickness, is noted in the
journal, and specimens are preserved. This bore is seen to penetrate the
strata _d_, _c_, _b_, _a_, without encountering any coal. Now, suppose
that the dip of the strata be one yard in ten, the question is, at what
distance from bore No. 1. in a south direction, will a second bore of 60
yards strike the first stratum _d_, of the preceding? The rule obviously
is, to multiply the depth of the bore by the dip, that is, 60 by 10, and
the product 600 gives the distance required; for, by the rule of three,
if 1 yard of depression corresponds to 10 in horizontal length, 60 yards
of depression will correspond to 600 in length. Hence the bores marked
1, 2, 3, 4, and 5, are successively distributed as in the figure, the
spot where the first is let down being regarded as the point of level to
which the summits of all the succeeding bores are referred. Should the
top of No. 2. bore be 10 yards higher or lower than the top of No. 1.,
allowance must be made for this difference in the operation; and hence a
surface level survey is requisite. Sometimes ravines cut down the
strata, and advantage should be taken of them, when they are
considerable.

In No. 2. a coal is seen to occur near the surface, and another at the
bottom of the bore; the latter seam resting on the first stratum _d_,
that occurred in bore No. 1.; and No. 2. perforation must be continued a
little farther, till it has certainly descended to the stratum _d_. Thus
these two bores have, together, proved the beds to the depth of 120
yards.

No. 3. bore being placed according to the preceding rule, will pass
through two coal-seams near the surface, and after reaching to nearly
its depth of 60 yards, it will touch the stratum _h_, which is the upper
stratum of bore No. 2.; but since a seam of coal was detected in No. 2.,
under the stratum _h_, the proof is confirmed by running the borer down
through that coal. The field has now been probed to the depth of 180
yards. The fourth bore is next proceeded with, till the two coal-seams
met in No. 3. have been penetrated; when a depth of 240 yards has been
explored. Hence No. 4. bore could not reach the lower stratum _a_,
unless it were sunk 240 yards.

The fifth bore (No. 5.) being sunk in like manner, a new coal-seam
occurs within a few yards of the surface; but after sinking to the depth
at which the coal at the top of the fourth bore was found, an entirely
different order of strata will occur. In this dilemma, the bore should
be pushed 10 or 20 yards deeper than the 60 yards, to ascertain the
alternations of the new range of superposition. It may happen that no
coals of any value shall be found, as the figure indicates, in
consequence of a slip or dislocation of the strata at B, which has
thrown up all the coals registered in the former borings, to such an
extent that the strata _b_, _a_, of the first bore present themselves
immediately on perforating the slip, instead of lying at the depth of
300 yards (5 × 60), as they would have done, had no dislocation
intervened. Some coal-fields, indeed, are so intersected with slips as
to bewilder the most experienced miner, which will particularly happen
when a lower coal is thrown upon one side of a slip, directly opposite
to an upper coal situated on the other side of it; so that if the two
seams be of the same thickness, erroneous conclusions are almost
inevitable.

When a line of bores is to be conducted from the dip of the strata
towards their outcrop, they should be placed a few yards nearer each
other than the rule prescribes, lest the strata last passed through be
overstepped, so that they may disappear from the register, and a
valuable coal-seam may thereby escape notice. In fact, each successive
bore should be so set down, that the first of the strata perforated
should be the last passed through in the preceding bore; as is
exemplified by viewing the bores in the retrograde direction, Nos. 4. 3.
and 2. But if the bore No. 2. had gone no deeper than _f_, and the bore
No. 1. been as represented, then the stratum _e_, with its immediately
subjacent coal, would have been overstepped, since none of the bores
would have touched it; and they would have remained unnoticed in the
journal, and unknown.

[Illustration: 821]

When the line of dip, and consequently the line of bearing which is at
right angles to it, are unknown, they are sought for by making three
bores in the following position.--Let _fig._ 821. be a horizontal
diagram, in which the place of a bore, No. 1., is shown, which reaches
a coal-seam at the depth of 50 yards; bore No. 2. may be made at B, 300
yards from the former; and bore No. 3. at C, equidistant from Nos. 1.
and 2., so that the bores are sunk at the three angles of an equilateral
triangle. If the coal occur in No. 2. at the depth of 30 yards, and in
No. 3. of 44 yards, it is manifest that none of the lines A B, B C, or C
A is in the line of level, which for short distances may be taken for
the line of bearing, with coal-seams of moderate dip. But since No. 1.
is the deepest of the three bores, and No. 3. next in depth, the line A
C joining them must be nearer the line of level, than either of the
lines A B or B C. The question is, therefore, at what distance on the
prolonged line B C is the point for sinking a bore which would reach the
coal at the same depth as No. 1., namely 50 yards. This problem is
solved by the following rule of proportion: as 14 yards (the difference
of depth between bores 2. and 3.) is to 300 yards (the distance between
them), so is 20 (the difference of depth betwixt 1. and 2.) to a fourth
proportion, or _x_ = 428 yards, 1 foot, and 8 inches. Now, this
distance, measured from No. 2., reaches to the point D on the prolonged
line B C, under which point D the coal will be found at a depth of 50
yards, the same as under A. Hence the line A D is the true level line of
the coal-field; and a line B F G drawn at right angles to it, is the
true dip-line of the plane which leads to the outcrop. In the present
example the dip is 1 yard in 14-1/2; or 1 in 14-1/2, to adopt the
judicious language of the miner; or the sine is 1 to a radius of 14-1/2,
measured along the line from B to F. By this theorem for finding the
lines of dip and level, the most eligible spot in a coal-field for
sinking a shaft may be ascertained.

Suppose the distance from B to G in the line of dip to be 455 yards;
then, since every 14-1/2 gives a yard of depression, 455 will give 30
yards, which added to 30 yards, the depth of the bore at B, will make 60
yards for the depth of the same coal-seam at G. Since any line drawn at
right angles to the line of level A D is the line of dip, so any line
drawn parallel to A D is a level line. Hence, if from C the line C E be
drawn parallel to D A, the coal-seam at the points E and C will be found
in the same horizontal plane, or 44 yards beneath the surface level,
over these two points. The point E level with C may also be found by
this proportion: as 20 yards (the difference in depth of the bores under
B and A) is to 300 yards (the distance between them), so is 14 yards
(the difference of depth under B and C) to 210 yards, or the distance
from B to E.

As boring for coal is necessarily carried on in a line perpendicular to
the horizon, and as coal seams lie at every angle of inclination to it,
the thickness of the seam as given obliquely by the borer, is always
greater than the direct thickness of the coal; and hence the length of
that line must be multiplied by the cosine of the angle of dip, in order
to find the true power of the seam.

_Of fitting or winning a coal-field._--In sinking a shaft for working
coal, the great obstacle to be encountered, is water, particularly in
the first opening of a field, which proceeds from the surface of the
adjacent country; for every coal-stratum, however deep it may lie in one
part of the basin, always rises till it meets the alluvial cover, or
crops out, unless it be met by a slip or dike. When the basset-edge of
the strata is covered with gravel or sand, any body or stream of water
will readily percolate downwards through it, and fill up the porous
interstices between the coal-measures, till arrested by the face of a
slip, which acts as a valve or flood-gate, and confines the water to one
compartment of the basin, which may, however, be of considerable area,
and require a great power of drainage.

In reference to water, coal-fields are divided into two kinds; 1., level
free coal; 2., coal not level free. In the practice of mining, if a
coal-field, or portion of it, is so situated above the surface of the
ocean that a level can be carried from that plane till it intersects the
coal, all the coal above the plane of intersection is said to be level
free; but if a coal-field, though placed above the surface of the ocean,
cannot, on account of the expense, be drained by a level or gallery, but
by mechanical power, such a coal-field is said to be not level free.

Besides these general levels of drainage, there are subsidiary levels,
called off-takes or drifts, which discharge the water of a mine, not at
the mouth of the pit, but at some depth beneath the surface, where, from
the form of the country, it may be run off level free. From 20 to 30
fathoms off-take is an object of considerable economy in pumping; but
even less is often had recourse to; and when judiciously contrived, may
serve to intercept much of the crop water, and prevent it from getting
down to the dip part of the coal, where it would become a heavy load on
a hydraulic engine.

Day levels were an object of primary importance with the early miners,
who had not the gigantic pumping power of the steam-engine at their
command. Levels ought to be no less than 4 feet wide, and from 5 feet
and a half to 6 feet high: which is large enough for carrying off
water, and admitting workmen to make repairs and clear out depositions.
When a day-level, however, is to serve the double purpose of drainage
and an outlet for coals, it should be nearly 5 feet wide, and have its
bottom gutter covered over. In other instances a level not only carries
off the water from the colliery, but is converted into a canal for
bearing boats loaded with coals for the market. Some subterranean canals
are nine feet wide, and twelve feet high, with 5 feet depth of water.

[Illustration: 822 823]

If in the progress of driving a level, workable coals are intersected
before reaching the seam which is the main object of the mining
adventure, an air-pit may be sunk, of such dimension as to serve for
raising the coals. These air-pits do not in general exceed 7 foot in
diameter; and they ought to be always cylindrical. _Fig._ 822.
represents a coal-field where the winning is made by a day-level; _a_ is
the mouth of the gallery on a level with the sea; _b_, _c_, _d_, _e_,
are intersected coal-seams, to be drained by the gallery. But the coals
beneath this level must obviously be drained by pumping. A represents a
coal-pit sunk on the coal _e_; and if the gallery be pushed forward, the
coal-seams _f_, _g_, and any others which lie in that direction, will
also be drained, and then worked by the pit A. The chief obstacle to the
execution of day-levels, is presented by quicksands in the alluvial
cover, near the entrance of the gallery. The best expedient to be
adopted amid this difficulty is the following:--_Fig._ 823. represents
the strata of a coal-field A, with the alluvial earth _a_, _b_,
containing the bed of quicksand _b_. The lower part, from which the
gallery is required to be carried, is shown by the line B _d_. But the
quicksand makes it impossible to push forward this day-level directly.
The pit B C must therefore be sunk through the quicksand by means of
_tubbing_ (to be presently described), and when the pit has descended a
few yards into the rock, the gallery or drift may then be pushed forward
to the point D, when the shaft E D is put down, after it has been
ascertained by boring that the rock-head or bottom of the quicksand at F
is a few yards higher than the mouth of the small pit B. During this
operation, all the water and mine-stuff, are drawn off by the pit B; but
whenever the shaft E D is brought into communication with the gallery,
the water is allowed to fill it from C to D, and rise up both shafts
till it overflows at the orifice B. From the surface of the water in the
deep shaft at G, a gallery is begun of the common dimensions, and pushed
onwards till the coal sought after is intersected. In this way no
drainage level is lost. This kind of drainage gallery, in the form of an
inverted syphon, is called a drowned or a blind level.

When a coal-basin is so situated that it cannot be rendered level free,
the winning must be made by the aid of machinery. The engines at present
employed in the drainage of coal-mines are:--

  1. The water-wheel, and water-pressure engine.
  2. The atmospheric steam-engine of Newcomen.
  3. The steam-engine, both atmospheric and double stroke, of Watt.
  4. The expansion steam-engine of Woolf.
  5. The high-pressure steam-engine, without a condenser.

The depth at which the coal is to be won, or to be drained of moisture,
regulates the power of the engine to be applied, taking into account the
probable quantity of water which may be found, a circumstance which
governs the diameter of the working barrels of the pumps. Experience has
proved, that in opening collieries, even in new fields, the water may
generally be drawn off by pumps of from 10 to 15 inches diameter;
excepting where the strata are connected with rivers, sand-beds filled
with water, or marsh-lands. As feeders of water from rivers or sand-beds
may be hindered from descending coal-pits, the growth proceeding from
these sources need not be taken into account; and it is observed, in
sinking shafts, that though the influx which cannot be cut off from the
mine, may be at first very great, even beyond the power of the engine
for a little while, yet as this excessive flow of water is frequently
derived from the drainage of fissures, it eventually becomes manageable.
An engine working the pumps for 8 or 10 hours out of the 24, is reckoned
adequate to the winning of a new colliery, which reaps no advantage from
neighbouring hydraulic powers. In the course of years, however, many
water-logged fissures come to be cut by the workings, and the coal seams
get excavated towards the outcrop, so that a constant increase of water
ensues, and thus a colliery which has been long in operation, frequently
becomes heavily loaded with water, and requires the action of its
hydraulic machinery both night and day.

[Illustration: 824 825 826]

_Of Engine Pits._--In every winning of coal, the shape of the engine-pit
deserves much consideration. For shafts of moderate depth, many forms
are in use; as circular, oval, square, octagonal, oblong rectangular,
and oblong elliptical. In pits of inconsiderable depth, and where the
earthy cover is firm and dry, any shape deemed most convenient may be
preferred; but in all deep shafts, no shape but the circular should be
admitted. Indeed, when a water-run requires to be stopped by tubbing or
cribbing, the circular is the only shape which presents a uniform
resistance in every point to the equable circumambient pressure. The
elliptical form is the next best, when it deviates little from the
circle; but even it has almost always given way to a considerable
pressure of water. The circular shape has the advantage, moreover, of
strengthening the shaft walls, and is less likely to suffer injury than
other figures, should any failure of the pillars left in working out the
coal cause the shaft to be shaken by subsidence of the strata. The
smallest engine-pit should be ten feet in diameter, to admit of the
pumps being placed in the lesser segment, and the coals to be raised in
the larger one, as shown in _fig._ 824., which is called a double pit.
If much work is contemplated in drawing coals, particularly if their
masses be large, it would be advantageous to make the pit more than 10
feet wide. When the area of a shaft is to be divided into three
compartments, one for the engine pumps, and two for raising coals, as in
_fig._ 825., which is denominated a triple pit, it should be 12 feet in
diameter. If it is to be divided into four compartments, and made a
quadrant shaft, as in _fig._ 826., with one space for the pumps, and
three for ventilation and coal-drawing, the total circle should be 15
feet in diameter. These dimensions are, however, governed by local
circumstances, and by the proposed daily discharge of coals.

The shaft, as it passes through the earthy cover, should be securely
faced with masonry of jointed ashler, having its joints accurately
bevelled to the centre of the circle. Specific directions for building
the successive masses of masonry, on a series of rings or cribs of oak
or elm, are given by Mr. Bald, article MINE, _Brewster’s Encyclopædia_,
p. 336.

[Illustration: 827]

When the alluvial cover is a soft mud, recourse must be had to the
operation of tubbing. A circular tub, of the requisite diameter, is made
of planks from 2 to 3 inches thick, with the joints bevelled by the
radius of the shaft, inside of which are cribs of hard wood, placed from
2 to 4 feet asunder, as circumstances may require. These cribs are
constructed of the best heart of oak, sawn out of the natural curvature
of the wood, adapted to the radius, in segments from 4 to 6 feet long,
from 8 to 10 inches in the bed, and 5 or 6 inches thick. The length of
the tub is from 9 to 12 feet, if the layer of mud have that thickness;
but a succession of such tubs must be set on each other, provided the
body of mud be thicker. The first tub must have its lower edge thinned
all round, and shod with sharp iron. If the pit be previously secured to
a certain depth, the tub is made to pass within the cradling, and is
lowered down with tackles till it rests fair among the soft alluvium. It
is then loaded with iron weights at top, to cause it to sink down
progressively as the mud is removed from its interior. Should a single
tub not reach the solid rock (sandstone or basalt), then another of like
construction is set on, and the gravitating force is transferred to the
top. _Fig._ 827. represents a bed of quicksand resting on a bed of
impervious clay, that immediately covers the rock. A is the finished
shaft; _a a_, the quicksand; _b b_, the excavation necessarily sloping
much outwards; _c c_, the lining of masonry; _d d_, the moating or
puddle of clay, hard rammed in behind the stone-work, to render the
latter water-tight. In this case, the quicksand, being thin in body, has
been kept under for a short period, by the hands of many men scooping it
rapidly away as it filled in. But the most effectual method of passing
through beds of quicksand, is by means of cast-iron cylinders; called,
therefore, cast-iron tubbing. When the pit has a small diameter, these
tubs are made about 4 feet high, with strong flanges, and bolt holes
inside of the cylinder, and a counterfort ring at the neck of the
flange, with brackets: the first tub, however, has no flange at its
lower edge, but is rounded to facilitate its descent through the mud.
Should the pit be of large diameter, then the cylinders must be cast in
segments of 3, 4, or more pieces, joined together with inside vertical
flanges, well jointed with oakum and white lead. When the sand-bed is
thick, eighty feet, for instance, it is customary to divide that length
into three sets of cylinders, each thirty feet long, and so sized as to
slide within each other, like the eye tubes of a telescope. These
cylinders are pressed down by heavy weights, taking care to keep the
lower part always further down than the top of the quicksand, where the
men are at work with their shovels, and where the bottom of the pumps
hangs for withdrawing the surface water. This is an improvement adopted
of late years in the Newcastle district with remarkable success.

The engine pit being secured, the process of sinking through the rock is
ready to be commenced, as soon as the divisions of the pit formed of
carpentry, called brattices, are made. In common practice, and where
great tightness of jointing is not required, for ventilating inflammable
air, bars of wood, called buntons, about 6 inches thick, and 9 deep, are
fixed in a horizontal position across the pit, at distances from each
other of 10, 20, or 30 feet, according to circumstances. Being all
ranged in the same vertical plane, deals an inch and a half thick are
nailed to them, with their joints perfectly close; one half of the
breadth of a bunton being covered by the ends of the deals. In deep
pits, where the ventilation is to be conducted through the brattice, the
side of the buntons next the pumps is covered with deals in the same
way, and the joints are rendered secure by being caulked with oakum.
Fillets of wood are also fixed all the way down on each side of the
brattice, constituting what is called a double pit.

When a shaft is to have 3 compartments, it requires more care to form
the brattice, as none of the buntons stretch across the whole space, but
merely meet near the middle, and join at certain angles with each other.
As the buntons must therefore sustain each other, on the principle of
the arch, they are not laid in a horizontal plane, but have a rise from
the sides towards the place of junction of 8 or 9 inches, and are bound
together by a three-tongued iron strap. Fillets of wood are carried down
the whole depth, not merely at the joinings of the brattice with the
sides of the pit, but also at their central place of union; while wooden
pillars connect the centre of each set of buntons with those above and
below. Thus the carpentry work acquires sufficient strength and
stiffness.

In quadrant shafts the buntons cross each other towards the middle of
the pit, and are generally let into each other about an inch, instead of
being half-checked. _Fig._ 824. is a double shaft: A, the pump pit; B,
the pit for raising coal. _Fig._ 825. is a triple shaft; in which A is
the pump compartment; B and C are coal pits. _Fig._ 826. is a quadrant
shaft: A, the pump pit; B, pit of ventilation or upcast for the smoke; C
and D, pits for raising coals.

[Illustration: 828]

A depth of 75 fathoms is fully the average of engine pits in Great
Britain. In practice, it embraces three sets of pumps. Whenever the
shaft is sunk so low that the engine is needed to remove the water, the
first set of pumps may be let down by the method represented in _fig._
828.; where A is the pump; _a a_, strong ears through which pass the
iron rods connected with the spears _b b_; _c c_ are the lashings; _d_,
the hoggar pump; _e_, the hoggar; _f f_, the tackles; _g g_, the single
pulleys; _h h_, the tackle fold leading to the capstans; and _i_, the
pump-spears. By this mechanical arrangement the pumps are sunk in the
most gradual manner, and of their own accord, so to speak, as the pit
descends. To the arms of the capstans, sledges are fastened with ropes
or chains; these sledges are loaded with weights, as counterpoises to
the weight of the column of pumps, and when additional pumps are joined
in, more weight is laid on the sledges. As the sinking set of pumps is
constantly descending, and the point for the delivery of the water above
always varying, a pipe of equal diameter with the pumps, and about 11
feet long, but much lighter in the metal, is attached to _e_, and is
terminated by a hose of leather, of sufficient length to reach the
cistern where the water is delivered. This is called the hoggar-pipe. In
sinking, a vast quantity of air enters with the water, at every stroke
of the engine; and therefore the lifting stroke should be very slow, and
a momentary stop should take place before the returning stroke, to
suffer all the air to escape. As the working barrels are generally 9 or
10 feet long, and the full stroke of the engine from 7 to 8 feet, when
at regular work, it is customary to diminish the length of stroke, in
sinking, to about 6 feet; because, while the pumps are constantly
getting lower, the bucket in the working barrel has its working range
progressively higher.

The usual length for a set of pumps, is from 25 to 30 fathoms. Whenever
this depth is arrived at by the first set, preparations are made for
fixing firmly the _upper_ pit-cistern, into which the upper set of pumps
is to be placed, and the water of the second set is to be thrown. If a
strong bed of sandstone occurs, a scarcement of it is left projecting
about 3 feet into the shaft, which is formed in the course of sinking
into a strong chin or bracket, to sustain that part of the cistern in
which the superior set of pumps stands. A few feet beneath this
scarcement the shaft resumes its usual shape.

[Illustration: 829]

But although from 20 to 30 fathoms be the common length of a pump-lift,
it sometimes becomes necessary to make it much longer, when no place can
be found in the shaft for lodging a cistern, on account of the tubbing.
Hence a pump-lift has been occasionally extended to 70 fathoms; which
requires extraordinary strength of materials. The best plan for
collaring the pumps in the pit, and keeping them steady in a
perpendicular line, is to fix a strong bunton of timber under the joints
of each pipe; and to attach the pipes firmly to these buntons by an iron
collar, with screws and nuts, as represented in _fig._ 829.

The water obtained in sinking through the successive strata is, in
ordinary cases, conducted down the walls of the shaft; and if the strata
are compact, a spiral groove is cut down the sides of the shaft, and
when it can hold no more, the water is drawn off in a spout to the
nearest pump-cistern; or a perpendicular groove is cut in the side of
the shaft, and a square box-pipe either sunk in it, flush with the sides
of the pit, or it is covered with deal boards well fitted over the
cavity. Similar spiral rings are formed in succession downwards, which
collect the trickling streams, and conduct them into the nearest
cistern; or rings, made of wood or cast iron, are inserted flush with
the sides of the pipe; and the water is led from one ring to another,
through perpendicular pipes, until the undermost ring is full, when it
delivers its water into the nearest pump-cistern. Keeping the shaft dry
is very important to the comfort of the miners, and the durability of
the work.

When an engine shaft happens to pass through a great many beds of coal,
a gallery a few yards long is driven into each coal-seam, and a bore
then put down from one coal to another, so that the water of each may
pass down through these bores to the pump-cisterns.

[Illustration: 830]

While a deep pit is sinking, a register is kept of every part of the
excavations, and each feeder of water is measured daily, to ascertain
its rate of discharge, and whether it increases or abates. The mode of
measurement, is by noting the time, with a seconds watch, in which a
cistern of 40 or 50 gallons gets filled. There are three modes of
keeping back or stopping up these feeders; by plank tubbing; iron
tubbing; and by oak cribs. Let _fig._ 830. represent the sinking of a
shaft through a variety of strata, having a top cover of sand, with much
water resting on the rock summit. Each plane of the coal-measure rises
in a certain direction till it meets the alluvial cover. Hence, the
pressure of the water at the bottom of the tubbing that rests on the
summit of the rock, is as the depth of water in the superficial
alluvium; and if a stratum _a_ affords a great body of water, while the
superjacent stratum _b_, and the subjacent _c_, are impervious to water;
if the porous bed _a_ be 12 feet thick, while no water occurs in the
strata passed through from the rock head, until that depth (supposed to
be 50 fathoms from the surface of the water in the cover); in this case,
the tubbing or cribbing must sustain the sum of the two water pressures,
or 62 fathoms; since the stratum _a_ meets the alluvial cover at _d_,
the fountain head of all the water that occurs in sinking. Thus we
perceive, that though no water-feeder of any magnitude should present
itself till the shaft had been sunk 100 fathoms; if this water required
to be stopped up or tubbed off through the breadth of a stratum only 3
feet thick, the tubbing floodgate would need to have a strength to
resist 100 fathoms of water-pressure. For though the water at first
oozes merely in discontinuous particles through the open pores of the
sands and sandstones, yet it soon fills them up, like a myriad of tubes,
which transfer to the bottom the total weight of the hydrostatic column
of 100 fathoms; and experience shows, as we have already stated, that
whatever water occurs in coal-pits or in mines, generally speaking,
proceeds from the surface of the ground. Hence, if the cover be an
impervious bed of clay, very little water will be met with among the
strata, in comparison of what would be found under sand.

[Illustration: 831 832]

When several fathoms of the strata must be tubbed, in order to stop up
the water-flow, the shaft must be widened regularly to admit the kind of
tubbing that is to be inserted; the greatest width being needed for
plank-tubbing, and the least for iron-tubbing. _Fig._ 831. represents a
shaft excavated for plank-tubbing, where _a_, _a_, _a_ are the
impervious strata, _b_, _b_ the porous beds water-logged, and _c_, _c_
the bottom of the excavation, made level and perfectly smooth with
mason-chisels. The same precautions are taken in working off the upper
part of the excavation _d_, _d_. In this operation, three kinds of cribs
are employed; called wedging, spiking, and main cribs. Besides the stout
plank for making the tub, a quantity of well-seasoned and clean reeded
deal is required for forming the joints; called sheeting deal by the
workmen. This sheeting deal is always applied in pieces laid endwise,
with the end of the fibres towards the area of the pit. Since much of
the security from water depends on the tightness of the tub at its
jointing with the rock, several plans have been contrived to effect this
object; the most approved being represented in _fig._ 832. To make room
for the lower wedging crib, the recess is excavated a few inches wider,
as at _c_; and from _b_ to _c_, sheeting deals are laid all round the
circle, or a thin stratum of oakum is introduced. On this the wedging
crib _d_ is applied, and neatly jointed in the radius-line of the pit,
each segment being drawn exactly to the circle: and at each of its
segments sheeting deal is inserted. This wedging crib must be 10 inches
in the bed, and 6 inches deep. The vacuity _e_, at the back of the crib,
about 2 and a half inches wide, is filled with pieces of dry clean
reeded deal, inserted endwise; which is regularly wedged with one set of
wedges all round, and then with a second and a third set of wedges, in
the same regular style, to keep the crib in a truly circular posture. By
this process, well executed, no water can pass downwards by the back of
the crib. The next operation is to fix spiking cribs _f_, to the rock,
about 10 or 12 feet from the lower crib, according to the length of the
planks to be used for the tubs. They must be set fair to the sweep of
the shaft, as on them its true circular figure depends. The tubbing
deals _k_, must now be fixed. They are 3 inches thick, 6 broad, and
planed on all sides, with the joints accurately worked to the proper
bevel for the circle of the pit. The main cribs _g_, _g_, are then to be
placed as counterforts, for the support and strength of the tubbing. The
upper ends of the first set of tub-planks being cut square and level all
round, the second spiking crib _l_, is fixed, and another set of tubbing
deals put round like the former, having sheeting deal inserted betwixt
the ends of the two sets at _f_. When this is wedged, the cribs _h_,
_h_, are placed.

Oak cribbing is made with pieces of the best oak, from 3 to 4 feet long,
10 inches in the bed, and 7 or 8 inches deep.

The third mode of tubbing, by means of iron cylinders cast in segments,
is likely henceforth to supersede the wooden tubbing, from the great
reduction in the price of iron, and its superior strength and
durability. Each segment is adjusted piece to piece in the circular
recess of the pit cut out for their reception. The flange for the
wedging joint is best turned inwards. In late improvements of this plan,
executed by Mr. Buddle, where the pressure amounted to several hundred
feet, the segments were 6 feet long, 2 feet broad, and an inch thick,
counterforted with ribs or raised work on the back; the lip of the
flange was strong, and supported by brackets. These segments of the iron
cylinder are set true to the radius of the pit; and every horizontal and
perpendicular joint is made tight with a layer of sheeting deal. A
wedging crib is fixed at the bottom, and the segments are built up
regularly with joints like ashler-work. This kind of tubbing can be
carried to any height, till the water finds an outlet at the surface, or
till strata containing water can be tubbed off, as by the modes of
tubbing already described. A shaft finished in this manner presents a
smooth lining-wall of iron, the flanges being turned towards the outside
of the cylinders. In this iron tubbing, no screw bolts are needed for
joining the segments together; as they are packed hard within the pit,
like the staves of a cask. There is a shaft in the Newcastle district,
where 70 fathoms have been executed in this way, under the direction of
Mr. Buddle.

[Illustration: 833]

When a porous thin bed or parting betwixt two impervious strata, gives
out much water, or when the fissures of the strata, called cutters, are
very leaky, the water can be completely stopped up by the improved
process of wedging. The fissure is cut open with chisels, to a width of
two, and a depth of seven inches, as represented in _fig._ 833. The lips
being rounded off about an inch and a half, pieces of clean deal are
then driven in, whose face projects no further than the contour of the
lips; when the whole is firmly wedged, till the water is entirely
stopped. By sloping back the edges of the fissures, and wedging back
from the face of the stone, it is not liable to burst or crack off in
the operation, as took place in the old way, of driving in the wedge
directly.

[Illustration: 834]

_Ventilation of Engine Pits._--In ordinary cases, while the sinking of
the shaft is going on, the brattice walls produce a circulation, in
consequence of the air being slightly lighter in one compartment than in
another. If this does not occur, the circulation of air must be produced
by artificial means. The most approved contrivance is, to cover the
engine compartment of the shaft with deals, leaving apertures for the
pump-spears and tackling to pass through, with hatch-doors for the men,
and to carry a brick flue at least 3 feet square, in a horizontal
direction, from the mouth of that compartment to an adjoining high
chimney connected with a furnace, as represented in _fig._ 834. _a_,
_a_, are double doors, for the fireman to supply fuel by; _b_, the mouth
of the horizontal flue; _c_, the furnace; _d_, the ash-pit; _e_, the
furnace; _f_, the upright chimney for draught, from 50 to 100 feet high,
from 8 to 10 feet square at bottom, and tapering upwards to 3 or 4 feet
square inside. Such a furnace and chimney are also needed for
ventilating the coal-mine through all its underground workings. When a
great quantity of gas issues from one place in a pit, it is proper to
carry it up in a square wooden pipe, which terminating at some distance
above the surface in a helmet-shaped funnel, fitted to turn like a vane,
may cause considerable ventilation of itself; or the top of such a pipe
may be connected with a small fireplace, which will cause a rapid
current up through it, from the pit. The stones and rubbish produced in
sinking, are drawn up with horse-gins, when the pit is not deep; but in
all shafts of considerable depth, a steam engine is used, and the
workmen have now more confidence in them, as to personal safety, than in
machines impelled by horses.

The great collieries of Newcastle are frequently worked by means of one
shaft divided into compartments, which serves as an engine-pit, and
coal-pits, and by these the whole ventilation is carried on to an extent
and through ramifications altogether astonishing. This system has been
adopted on account of the vast expense of a large shaft, often amounting
to 60,000_l._ or 80,000_l._, including the machinery. The British
collieries, however, are in general worked by means of an engine-pit,
and a series of other pits, sunk at proper distances for the wants of
the colliery.

WORKING OF COAL.

[Illustration: 835]

A stratum, bed, or seam of coal, is not a solid mass, of uniform
texture, nor always of homogeneous quality in burning. It is often
divided and intersected, with its concomitant strata, by what are named
partings, backs, cutters, reeds, or ends. Besides the chief partings at
the roof and pavement of the coal seam, there are subordinate lines of
parting in the coal mass, parallel to these of variable dimensions.
These divisions are delineated in _fig._ 835., where A, B, C, D, E F G
D, represent a portion of a bed of coal, the parallelogram A B D C the
parting at the roof, and E F G the parting at the pavement; _a b_, _b
c_, _d e_, and _e f_, are the subordinate or intermediate partings; _g
h_, _i k_, _l m_, the backs; _o p_, _p q_, _r s_, _s t_, _u v_, and _v
w_, the cutters. It is thus manifest that a bed of coal, according to
the number of these natural divisions, is subdivided into solid figures
of various dimensions, and of a cubical or rhomboidal shape.

[Illustration: 836 837]

When the engine-pit is sunk, and the lodgement formed, a mine is then
run in the coal to the rise of the field, or a cropping from the
engine-pit to the second pit. This mine may be 6 or 8 feet wide, and
carried either in a line directly to the pit bottom, or at right angles
to the backs or web of the coal, until it is on a line with the pit,
where a mine is set off, upon one side, to the pit bottom. This mine or
gallery is carried as nearly parallel to the backs as possible, till the
pit is gained. _Fig._ 836. represents this mining operation. A is the
engine-pit. B, the second or bye-pit. A C, the gallery driven at right
angles to the backs. C B, the gallery set off to the left hand, parallel
to the backs. The next step is to drive the drip-head or main-levels
from the engine-pit bottom, or from the dip-hand of the backset
immediately contiguous to the engine-pit bottom. In this business, the
best colliers are always employed, as the object is to drive the gallery
in a truly level direction, independently of all sinkings or risings of
the pavement. For coal seams of ordinary thickness, this gallery is
usually not more than 6 feet wide; observing to have on the dip side of
the gallery a small quantity of water, like that of a gutter, so that it
shall always be about 4 or 6 inches deep at the forehead upon the
dip-wall. When the level is driven correctly, with the proper depth of
water, it is said to have dead water at the forehead. In this operation,
therefore, the miner pays no regard to the backs or cutters of the coal;
but is guided in his line of direction entirely by the water-level,
which he must attend to solely, without regard to slips or dislocations
of the strata throwing the coal up or down. In the last figure, the
coal-field is a portion of a basin; so that if the shape be uniform and
unbroken, and if any point be assumed a dipping from the crop, as D, the
level lines from that point will be parallel to the line of crop, as D
E, D F, and the levels from any point whatever a-dipping, will be also
parallel to these; and hence, were the coal-field an entire elliptical
basin, the dip-head levels carried from any point would be elliptical,
and parallel to the crop. If, as is more commonly the case, the
coal-field be merely a portion of a basin, formed by a slip of the
strata, as represented in _fig._ 837., where _a_, _a_, _a_, is the crop,
and A B, a slip of great magnitude, forming another coal-field on the
side C, then the crop not only meets the alluvial cover, but is cut off
by the slip at A and at B. Should any point, therefore, be assigned for
an engine-pit, the levels from it will proceed in a line parallel to the
crop, as D _d_, D _c_, and the level on both sides of the engine-pit
will be also cut off by the slip A B. In this figure, the part included
between the two curve lines, is the breadth or breast of coal-field won
by the engine-pit D; what is not included, is termed the under-dip coal,
and can be worked only by one or more new winnings towards the dip,
according to circumstances.

In British practice, there are four different systems of working
coal-mines:--

1. Working with pillars and rooms, styled post and stall, where the
pillars left, bear such proportion to the coal excavated, as is just
adequate to the support of the incumbent strata.

2. Working with post and stall, where the pillars are left of an extra
size, and stronger than may be requisite for bearing the superior
strata, with the intention of removing a considerable portion of each
massive pillar, whenever the regular working of post and stall has been
finished in the colliery.

3. Working with post and stall, or with comparatively narrow rooms or
boards, whereby an uncommonly large proportion of coal is left, with the
view of working back towards the pits, whenever the colliery is worked
in this manner to the extent of the coal-field, and then taking away
every pillar completely, if possible, and allowing the whole
superincumbent strata to crush down, and follow the miners in their
retreat.

4. Working the long way, being the Shropshire method; which leaves no
pillars, but takes out all the coal progressively as the workings
advance. On this plan, the incumbent strata crush down, creeping very
close to the heads of the miners.

The post and stall system is practised with coals of every thickness.
The Shropshire method is adopted generally with thin coals; for when the
thickness exceeds 6 or 7 feet, this mode has been found impracticable.

The following considerations must be had in view in establishing a
coal-mine:--

1. The lowest coal of the winning should be worked in such a manner as
not to injure the working or the value of the upper coals of the field;
but if this cannot be done, the upper coals should be worked in the
first place.

2. The coals must be examined as to texture, hardness, softness, the
number and openness of the backs and cutters.

3. The nature of the pavement of the coal seam, particularly as to
hardness and softness; and if soft, to what depth it may be so.

4. The nature of the roof of the coal-seam, whether compact, firm, and
strong; or weak and liable to fail; as also the nature of the
superincumbent strata.

5. The nature of the alluvial cover of the ground, as to water,
quicksands, &c.

6. The situation of rivers, lakes, or marshes, particularly if any be
near the outcrop of the coal strata.

7. The situation of towns, villages, and mansion-houses, upon a
coal-field; as to the chance of their being injured by any particular
mode of mining the coal.

Mr. Bald gives the following general rules for determining the best mode
of working coal:--

“1. If the coal, pavement, and roof are of ordinary hardness, the
pillars and rooms may be proportioned to each other, corresponding to
the depth of the superincumbent strata, providing all the coal proposed
to be wrought is taken away by the first working, as in the first
system; but if the pillars are to be winged afterwards, they must be
left of an extra strength, as in the second system.

“2. If the pavement is soft, and the coal and roof strong, pillars of an
extra size must be left, to prevent the pillars sinking into the
pavement, and producing a creep.

“3. If the coal is very soft, or has numerous open backs and cutters,
the pillars must be left of an extra size, otherwise the pressure of the
superincumbent strata will make the pillars fly or break off at the
backs and cutters, the result of which would be a total destruction of
the pillars, termed a crush or sit, in which the roof sinks to the
pavement, and closes up the work.

“4. If the roof is very bad, and of a soft texture, pillars of an extra
size are required, and the rooms or boards comparatively very narrow.

“In short, keeping in view all the circumstances, it may be stated
generally, that when the coal, pavement, and roof are good, any of the
systems before mentioned may be pursued in the working; but if they are
soft, the plan is to work with rooms of a moderate width, and with
pillars of great extra strength, by which the greater part of the coal
may be got out at the last of the work, when the miners retreat to the
pit bottom, and there finish the workings of a pit.”

[Illustration: 838 839]

_Fig._ 838. represents the effects of pillars sinking into the pavement,
and producing a creep; and _fig._ 839. exhibits large pillars and a
room, with the roof stratum bending down before it falls at _a_. Thus
the roads will be shut up, the air-courses destroyed, and the whole
economy of the mining operations deranged.

The proportion of coal worked out, to that left in the pillars, when all
the coal intended to be removed is taken out at the first working,
varies from four-fifths to two-thirds; but as the loss of even
one-third of the whole area of coal is far too much, the better mode of
working suggested in the third system ought to be adopted.

[Illustration: 840]

The proportion of a winning to be worked maybe thus calculated. Let
_fig._ 840. be a small portion of the pillars, rooms, and thirlings
formed in a coal-field; _a_, _a_, are two rooms; _b_, the pillars; _c_,
the thirlings (or area worked out). Suppose the rooms to be 12 feet
wide, the thirlings to be the same, and the pillars 12 feet on each
side; adding the face of the pillar to the width of the room, the sum is
24; and also the end of the pillar to the width of the thirling, the sum
is likewise 24: then 24 × 24 = 576; and the area of the pillar is 12 ×
12 = 144; and as 576 divided by 144, gives 4 for a quotient, the result
is, that one fourth of the coal is left in pillars, and three fourths
extracted. Let _d_, _e_, _f_, _g_, be one winning, and _g_, _e_, _k_,
_h_, another. By inspecting the figure, we perceive the workings of a
coal-field are resolved into quadrangular areas, having a pillar
situated in one of the angles.

[Illustration: 841]

In forming the pillars and carrying forwards the boards with regularity,
especially where the backs and cutters are very distinct and numerous,
it is of importance to work the rooms at right angles to the backs, and
the thirlings in the direction of the cutters, however oblique these may
be to the backs, as the rooms are by this means conducted with the
greatest regularity with regard to each other, kept equidistant, and the
pillars are strongest under a given area. At the same time, however, it
seldom happens that a back or cutter occurs exactly at the place where a
pillar is formed; but this is of no consequence, as the shearing or
cutting made by the miner ought to be in a line parallel to the backs
and cutters. It frequently happens that the dip-head level intersects
the cutters in its progress at a very oblique angle. In this case, when
rooms and pillars are set off, the face of the pillar and width of the
room must be measured off an extra breadth in proportion to the
obliquity, as in _fig._ 841. By neglect of this rule, much confusion and
irregular work is often produced. It is, moreover, proper to make the
first set of pillars next the dip-head level much stronger, even where
there is no obliquity, in order to protect that level from being injured
by any accidental crush of the strata.

[Illustration: 842]

We shall now explain the different systems of working; one of the
simplest of which is shown in _fig._ 842; where A represents the
engine-pit, B the bye-pit, C D the dip-head levels, always carried in
advance of the rooms, and E the rise or crop gallery, also carried in
advance. These galleries not only open out the work for the miners in
the coal-bed, but, being in advance, afford sufficient time for any
requisite operation, should the mines be obstructed by dikes or hitches.
In the example before us, the rooms or boards are worked from the dip to
the crop; the leading rooms, or those most in advance, are on each side
of the crop gallery E; all the other rooms follow in succession, as
shown, in the figure; consequently, as the rooms advance to the crop,
additional rooms are begun at the dip-head level, towards C and D.
Should the coal work better in a level-course direction, then the level
rooms are next the dip-head level, and the other rooms follow in
succession. Hence the rooms are carried a cropping in the one case, till
the coal is cropped out, or is no longer workable; and in the other,
they are extended as far as the extremity of the dip-head level, which
is finally cut off, either by a dike or slip, or by the boundary of the
coal-field.

When the winnings are so very deep as from 100 to 200 fathoms, the first
workings are carried forward with rooms, pillars, and thirlings, but
under a different arrangement, on account of the great depth of the
superincumbent strata, the enormous expense incident to sinking a pit,
and the order and severity of discipline indispensable to the due
ventilation of the mines, the preservation of the workmen, and the
prosperity of the whole establishment. To the celebrated Mr. Buddle the
British nation is under the greatest obligations for devising a new
system of working coal-mines, whereby nearly one-third of the coals has
been rescued from waste and permanent destruction. This system is named
panel work; because, instead of carrying on the coal-field winning in
one extended area of rooms and pillars, it is divided into quadrangular
panels, each panel containing an area of from 8 to 12 acres; and round
each panel is left at first a solid wall of coal from 40 to 50 yards
thick. Through the panel walls roads and air-courses are driven, in
order to work the coal contained within these walls. Thus all the panels
are connected together with the shaft, as to roads and ventilation. Each
district or panel has a particular name; so that any circumstance
relative to the details of the colliery, casualties as to falls and
crushes, ventilation, and the safety of the workmen, can be referred to
a specific place.

[Illustration: 843]

_Fig._ 843. represents a part of a colliery laid out in four panels,
according to the improved method. To render it as distinct as possible,
the line of the boards is at right angles with the dip-head level, or
level course of the coal. A is the engine-shaft, divided into three
compartments, an engine-pit and two coal-pits, like _fig._ 825. One of
the coal-pits is the down-cast, by which the atmospheric air is drawn
down to ventilate the works; the other coal-pit is the up-cast shaft, at
whose bottom the furnace for rarefying the air is placed. B C, is the
dip-head level; A E, the rise or crop gallery; K, K, the panel walls; F,
G, are two panels completed as to the first work; D, is a panel, with
the rooms _a_, _a_, _a_, in regular progress to the rise; H, is a panel
fully worked out, whence nearly all the coal has been extracted; the
loss amounting in general to no more than a tenth, instead of a third,
or even a half, by the old method. By this plan of Mr. Buddle’s, also,
the pillars of a panel may be worked out at any time most suitable for
the economy of the mining operation; whereas formerly, though the size
of the pillars and general arrangement of the mine were made with the
view of taking out ultimately a great proportion of the pillars, yet it
frequently happened that, before the workings were pushed to the
proposed extent, some part of the mine gave way, and produced a crush;
but the most common misfortune was the pillars sinking into the
pavement, and deranging the whole economy of the field. Indeed the crush
or creep often overran the whole of the pillars, and was resisted only
by the entire body of coal at the wall faces; so that the ventilation
was entirely destroyed, the roads leading from the wall faces to the
pit-bottom shut up and rendered useless, and the recovery of the
colliery by means of new air-courses, new roads, and by opening up the
wall faces or rooms, was attended with prodigious expense and danger.
Even when the pillars stood well, the old method was attended with other
very great inconveniences. If water broke out in any particular spot of
the colliery, it was quite impossible to arrest its progress to the
engine-pit; and if the ventilation was thereby obstructed, no idea could
be formed where the cause might be found, there being instances of no
less than 30 miles of air-courses in one colliery. And if from
obstructed ventilation an explosion of the fire-damp occurred while many
workmen were occupied along the extended wall faces, it was not possible
to determine where the disaster had taken place; nor could the viewers
and managers know where to bring relief to the forlorn and mutilated
survivors.

In Mr. Buddle’s system all these evils are guarded against, as far as
human science and foresight can go. He makes the pillars very large, and
the rooms or boards narrow; the pillars being in general 12 yards broad,
and 24 yards long; the boards 4 yards wide, and the walls or thirlings
cut through the pillars from one board to another, only 5 feet wide, for
the purpose of ventilation. In the figure, the rooms are represented as
proceeding from the dip to the crop, and the panel walls act as barriers
thrown round the area of the panel, to prevent the weight of the
superincumbent strata from overrunning the adjoining panels. Again, when
the _pillars_ of a panel are to be worked, one range of pillars, as at I
(in H), is first attacked; and as the workmen cut away the furthest
pillars, columns of prop-wood are erected betwixt the pavement and the
roof, within a few feet of each other (as shown by the dots), till an
area of above 100 square yards is cleared of pillars, presenting a body
of-strata perhaps 130 fathoms thick, suspended clear and without
support, except at the line of the surrounding pillars. This operation
is termed working the _goaff_. The only use of the prop-wood is to
prevent the seam, which forms the ceiling over the workmen’s heads, from
falling down and killing them by its splintery fragments. Experience has
proved, that before proceeding to take away another set of pillars, it
is necessary to allow the last-made goaff to fall. The workmen then
begin to draw out the props, which is a most hazardous employment. They
begin at the more remote props, and knock them down one after another,
retreating quickly under the protection of the remaining props.
Meanwhile the roof-stratum begins to break by the sides of the pillars,
and falls down in immense pieces; while the workmen still persevere,
boldly drawing and retreating till every prop is removed. Nay, should
any props be so firmly fixed by the top pressure, that they will not
give way to the blows of heavy mauls, they are cut through with axes;
the workmen making a point of honour to leave not a single prop in the
goaff. The miners next proceed to cut away the pillars nearest to the
sides of the goaff, setting prop-wood, then drawing it, and retiring as
before, until every panel is removed, excepting small portions of
pillars which require to be left under dangerous stones to protect the
retreat of the workmen. While this operation is going forward, and the
goaff extending, the superincumbent strata being exposed without support
over a large area, break progressively higher up; and when strong beds
of sandstone are thus giving way, the noise of the rending rocks is very
peculiar and terrific; at one time loud and sharp, at another hollow and
deep.

As the pillars of the panels are taken away, the panel walls are also
worked progressively backwards to the pit bottom; so that only a very
small proportion of coal is eventually lost. This method is undoubtedly
the best for working such coals as those of Newcastle, considering their
great depth beneath the surface, their comparative softness, and the
profusion of inflammable air. It is evident that the larger the pillars
and panel walls are, in the first working, the greater will be the
security of the miners, and the greater the certainty of taking out, in
the second stage, the largest proportion of coal. This system may be
applied to many of the British collieries; and it will produce a vast
quantity of coals beyond the post and stall methods, so generally
persisted in.

In thus tearing to pieces the massive rocks over his head, the miner
displays a determined and cool intrepidity; but his ingenuity is no less
to be admired in contriving modes of carrying currents of pure
atmospheric air through every turning of his gloomy labyrinth, so as to
sweep away the explosive spirit of the mine.

The fourth system of working coal, is called the _long way_, the
long-wall, and the Shropshire method. The plan must at first have been
extremely hazardous; though now it is so improved as to be reckoned as
safe, if not safer, to the workmen, than the other methods, with rooms
and pillars.

The object of the Shropshire system, is to begin at the pit-bottom
pillars, and to cut away at once every inch of coal progressively
forward, and to allow the whole superincumbent strata to crush down
behind and over the heads of the workmen. This plan is pursued chiefly
with coals that are thin, and is very seldom adopted when the seam is 7
feet thick; from 4 to 5 feet being reckoned the most favourable
thickness for proceeding with comfort, amidst ordinary circumstances, as
to roof, pavement, &c. When a pit is opened on a coal to be treated by
this method, the position of the coals above the lowest seam sunk to,
must first be considered; if the coal beds be contiguous, it will be
proper to work the upper one first, and the rest in succession
downwards; but if they are 8 fathoms or more apart, with strata of
strong texture betwixt them, the working of the lower coals in the first
place will do no injury to that of the upper coals, except breaking
them, perhaps, a little. In many instances, indeed, by this operation on
a lower coal, upper coals are rendered more easily worked.

[Illustration: 844]

When the operation is commenced by working on the Shropshire plan, the
dip-head levels are driven in the usual manner, and very large bottom
pillars are formed, as represented in _fig._ 844. Along the rise side of
the dip-head level, chains of wall, or long pillars, are also made, from
8 to 10 yards in breadth, and only mined through occasionally, for the
sake of ventilation, or of forming new roads. In other cases no pillars
are left upon the rise side of the level; but, instead of them,
buildings of stone are reared, 4 feet broad at the base, and 9 or 10
feet from the dip side of the level. Though the roads are made 9 feet
wide at first, they are reduced to half that width after the full
pressure of the strata is upon them. Whenever these points are secured,
the operation of cutting away the whole body of the coal begins. The
place where the coal is removed, is named the _gobb_ or waste; and
gobbin, or gobb-stuff, is stones or rubbish taken away from the coal,
pavement, or roof, to fill up that excavation as much as possible, in
order to prevent the crush of superincumbent strata from causing heavy
falls, or following the workmen too fast in their descent. Coals mined
in this manner work most easily according to the way in which the widest
backs and cutters are; and therefore, in the Shropshire mode, the walls
stand sometimes in one direction, and sometimes in another; the mine
always turning out the best coals when the open backs and cutters face
the workmen. As roads must be maintained through the crushed strata, the
miners in the first place cut away about 15 feet of coal round the
pit-bottom pillars, and along the upper sides of the dip-head chain
walls; and then, at the distance of 9 or 10 feet, carry regular
buildings of stone 3 feet broad, with props set flush with the faces of
these, if necessary. As the miners advance, they erect small pillars of
roof or pavement stone in regular lines with the wall face, and
sometimes with props intermediate.

There are two principal modifications of the Shropshire plan. The first,
or the original system, was to open out the wall round the pit-bottom;
and, as the wall face extended, to set off main roads and branches, very
like the branches of a tree. These roads were so distributed, that
between the ends of any two branches there should be a distance of 30 or
40 yards, as might be most convenient. (see _fig._ 844.) Each space of
coal betwixt the roads is called a wall; and one half of the coals
produced from each wall is carried to the one road, and the other half
to the other road. This is a great convenience when the roof is bad; and
hence a distance of only 20 yards betwixt the roads is in many instances
preferred. In _fig._ 844. A represents the shaft; B B, the wall-face;
_a_, the dip-head level; _b_, the roads, from 20 to 40 yards asunder;
_c_, the _gobb_ or waste, with buildings along the sides of the roads;
and _d_, the pillars.

[Illustration: 845]

The other Shropshire system is represented in _fig._ 845., where A shows
the pit, with the bottom pillars; _b_, the dip-head levels; _c_, the
off-break from the level, where no pillars are left; _d_, the off-break,
where pillars remain to secure the level. All roads are protected in the
sides by stone buildings, if they can be had, laid off 9 feet wide.
After the crush settles, the roads generally remain permanently good,
and can, in many cases, be travelled through as easily 50 years after
they have been made, as at the first. Should stones not be forthcoming,
coals must be substituted, which are built about 20 inches in the base.
In this method, the roads are likewise from 20 to 40 yards apart; but
instead of ramifying, they are arranged parallel to each other. The
miners secure the waste by gobbing; and three rows of props are carried
forwards next the wall faces _a_, with pillars of stone or of coal
reared betwixt them. This mode has a more regular appearance than the
other; though it is not so generally practised.

In the post and stall system, each man has his own room, and performs
all the labour of it; but in that of Shropshire, there is a division of
labour among the workmen, who are generally divided into three
companies. The first set curves or pools the coal along the whole line
of walls, laying in or pooling at least 3 feet, and frequently 45
inches, or 5 quarters, as it is called. These men are named _holers_. As
the crush is constantly following them, and impending over their heads,
causing frequent falls of coal, they plant props of wood for their
protection at regular distances in an oblique direction between the
pavement and wall face. Indeed, as a further precaution, staples of
coal, about 10 inches square, are left at every 6 or 8 yards, till the
line of holing or curving is completed. The walls are then marked off
into spaces of from 6 to 8 yards in length; and at each space a shearing
or vertical cut is made, as deep as the holing; and when this is done,
the holer’s work is finished. The set who succeed the holers, are called
getters. These commence their operations at the centre of the wall
divisions, and drive out the _gibbs_ and staples. They next set wedges
along the roof, and bring down progressively each division of coal; or,
if the roof be hard-bound, the coal is blown down with gunpowder. When
the roof has a good parting, the coals frequently fall down the moment
the gibbs are struck; which makes the work very easy. The getters are
relieved in their turn by the third set, named butty-men, who break down
the coals into pieces of a proper size for sending up the shaft, and
take charge of turning out the coal from the wall face to the ends of
the roads. This being done, they build up the stone pillars, fill up the
gobb, set the trees, clear the wall faces of all obstructions, set the
gibbs, and make every thing clear and open for the holers to resume
their work. If the roads are to be heightened by taking down the roof,
or removing the pavement, these butty-men do this work also, building
forwards the sides of the roads, and securing them with the requisite
props. When a coal has a following or roof stone, which regularly
separates with the coal, this facilitates the labour, and saves much of
the coal; and should a soft bed of fire-clay occur a foot or two
beneath the coal-seam, the holing is made in it, instead of into the
coal, and the stone betwixt the holing and the coal benched down, which
serves for pillars and gobbing. In this way all the vendible coal
becomes available.

[Illustration: 846]

Another form of the Shropshire system is, for each miner to have from 6
to 12 feet of coal before him, with a leading-hand man; and for the
several workmen to follow in succession, like the steps of a stair. When
the coal has open backs and cutters, this work goes on very regularly,
as represented in _fig._ 846., where the leading miner is at _a_, next
to the outcrop, and _b b_, &c. are the wall faces of each workman; A
being the shaft, and B the dip-head level. In this case the roads are
carried either progressively through the gobb, or the gobb is entirely
shut up; and the whole of the coals are brought down the wall-faces,
either to the dip-head level or the road _c_, _c_. This method may be
varied by making the walls broad enough to hold two, three, or four men
when each set of miners performs the whole work of holing, getting,
breaking down, and carrying off the coals.

It is estimated that from one-eighth to one-twelfth part only of the
coals remains underground by the Shropshire plan; nay, in favourable
circumstances, almost every inch of coal may be taken out, as its
principle is to leave no solid pillars nor any coal below, except what
may be indispensable for securing the gobb. Indeed this system might be
applied to coal seams of almost any ordinary thickness, providing stuff
to fill up the gobb could be conveniently procured.

In Great Britain, seams of coal are mined when they are only 18 inches
thick; but if thinner, the working of fire-clay or ironstone immediately
adjoining must be included. A few instances may be adduced, indeed,
where caking coals of a fine quality for blacksmiths have been worked,
though only in 12-inch seams.

Eighteen-inch seams are best worked by young lads and boys. The coal
itself may be mined without lifting the pavement, or taking down the
roof in the rooms; but roads must be cut either in the pavement or the
roof, for removing the coals to the pit-bottom. All coals less than 2
feet 3 inches thick, are worked with the view of taking out all the
coal, either on the Shropshire system, or with pillar-walls and rooms;
with this peculiarity, that, on account of the thinness of the seam, the
rooms are worked as wide as the roof will bear up; or if a following of
the roof-stone, or fall of it, can be brought on, it proves
advantageous, by not only giving head-room, but by filling up the waste,
and rendering the roads easily kept for the working of the pillars.
Where no following takes place, small temporary pillars, about 8 feet
square, are left along the chain-wall side. The walls may vary in
thickness from 4 to 16 yards, according to circumstances, and they are
holed through only for ventilation.

Coals from 5 to 8 feet thick are the best suited in every point of view
for the effective work of the miner, and for the general economy of
underground operations. When they exceed that thickness, they require
very excellent roofs and pavements, to render the working either safe or
comfortable; or to enable those who superintend the field to get out a
fair proportion of coal from a given area. In such powerful beds the
Shropshire method is impracticable, from want of gobbin; and long props,
unless of prodigious girth, would present an inadequate resistance to
the pressure of the massive ceiling.

[Illustration: 847]

When coals do not exceed 20 feet in thickness, and have good roofs, they
are sometimes worked as one bed of coal; but if the coal be tender or
free, it is worked as two beds. One-half of such thick coal, however, is
in general lost in pillars; and it is very seldom that less than
one-third can be left. When the coal is free and ready to crumble by the
incumbent pressure, as well as by the action of the air, the upper
portion of the coal is first worked, then a scaffolding of coal is left,
2 or 3 feet thick, according to the compactness of the coal; and the
lower part of the coal is now worked, as shown in _fig._ 847. As soon as
the workings are completed to the proposed extent, the coal scaffoldings
are worked away, and as much of the pillars as can be removed with
safety. As propwood is of no use in coal seams of such a height, and as
falls from the roof would prove frequently fatal to the miners, it is
customary with tender roofs to leave a ceiling of coal from 2 to 3 feet
thick. This makes an excellent roof; and should it break, gives warning
beforehand, by a peculiar crackling noise, very different from that of
roof-stones crushing down.

One of the thickest coals in Great Britain, worked as one bed from roof
to pavement, is the very remarkable seam near the town of Dudley, known
by the name of the ten-yard coal, about 7 miles long, and 4 broad. No
similar coal has been found in the island; and the mode of working it is
quite peculiar, being a species of panel work totally different from
the modern Newcastle system. A compartment, or pannel, formed in working
the coal, is called a side of work; and as the whole operation is
exhibited in one of these compartments, it will be proper to describe
the mode of taking the coal from one of them, before describing the
whole extent of the workings of a mine.

[Illustration: 848]

Let _fig._ 848. represent a side of work; A, the ribs or walls of coal
left standing round, constituting the side of work; _a_, the pillars, 8
yards square; _c_, the stalls, 11 yards wide; _d_, the cross openings,
or through puts, also 11 yards wide; _e_, the bolt-hole, cut through the
rib from the main road, by which bolt-hole the side of work is opened
up, and all the coals removed. Two, three, or even four bolt-holes open
into a side of work, according to its extent; they are about 8 feet
wide, and 9 feet high. The working is in a great measure regulated by
the natural fissures and joints of the coal-seam; and though it is 30
feet thick, the lower band, of 2 feet 3 inches, is worked first; the
miners choosing to confine themselves within this narrow opening, in
order to gain the greater advantage afterwards, in working the
superjacent coal. Whenever the bolt hole is cut through, the work is
opened up by driving a gallery forward, 4 feet wide, as shown by the
dotted lines. At the sides of this gallery next the bolt-hole, each
miner breaks off in succession a breast of coal, two yards broad, as at
_f_, _f_, by means of which the sides of the rib-walls A, are formed,
and the area of the pillars. In this way each collier follows another,
as in one of the systems of the Shropshire plan. When the side of work
is laid open along the rib-walls, and the faces and sides of the pillars
have been formed, the upper coals are then begun to be worked, next the
rib-wall. This is done by shearing up to a bed next the bolt-hole, and
on each side, whereby the head coals are brought regularly down in large
cubical masses, of such thickness as suits with the free partings or
subordinate divisions of the coals and bands. Props of wood, or even
stone pillars, are placed at convenient distances for the security of
the miners.

In working the ten-yard coal, a very large proportion of it is left
underground, not merely in pillars and rib-walls, but in the state of
small coal produced in breaking out the coal. Hence, from four-tenths to
a half of the total amount is lost for ever.

[Illustration: 849]

Another method of working coal of uncommon thickness, is by scaffoldings
or stages of coals, as practised in the great coal bed at Johnstone,
near Paisley, of which a section has already been given. In one part of
the field the coal is from 50 to 60 feet thick, and in another it
amounts to 90 feet. The seams of stone interspersed through the coal are
generally inconsiderable, and amount in only two cases to 27 inches in
thickness. The roof of the coal is so unsound, and the height so
prodigious, that it could not possibly be worked in one seam, like that
of Staffordshire. About 3 feet of the upper coal is therefore left as a
roof, under which a band of coal, from 6 to 7 feet thick, is worked on
the post and stall plan, with square pillars of extra strength, which
are thereafter penetrated. A platform about 3 feet high is left at the
sole; under which the rooms and pillars are set off and worked in
another portion of the coal, from 5 to 7 feet thick, great care being
had to place pillar under pillar, and partition under partition, to
prevent a crush. Where the coal is thickest, no less than 10 bands of it
are worked in this way, as is shown in _fig._ 849. When any band of the
coal is foul from sulphur or other causes, it is left for the next
platform, so that a large proportion of it is lost, as in the
Staffordshire mines. Much attention must here be paid to the vertical
distribution of the pillars and apartments; the miner’s compass must be
continually consulted, and bore-holes must be put down through the coal
scaffoldings, to regulate correctly the position of the pillars under
one another.

_Edge coals_, which are nearly perpendicular, are worked in a peculiar
manner; for the collier stands upon the coal, having the roof on the one
hand, and the floor on the other, like two vertical walls. The
engine-pit is sunk in the most powerful stratum. In some instances the
same stratum is so vertical as to be sunk through for the whole depth of
the shaft.

[Illustration: 850]

Whenever the shaft has descended to the required depth, galleries are
driven across the strata from its bottom, till the coals are
intersected, as is shown in _fig._ 850., where we see the edge coals at
_a_, _a_; A, the engine-pit; _b_, _b_, the transverse galleries from the
bottom of the shaft; and _c_, _c_, upper transverse galleries, for the
greater conveniency of working the coal. The principal edge coal works
in Great Britain lie in the neighbourhood of Edinburgh, and the coals
are carried on the backs of women from the wall-face to the bottom of
the engine-pit.

The modes of carrying coals from the point where they are excavated to
the pit bottom, are nearly as diversified as the systems of working.

One method employs hutches, or baskets, having slips or cradle feet shod
with iron, containing from 2 to 3 hundred weight of coals. These baskets
are dragged along the floor by ropes or leather harness attached to the
shoulders of the workmen, who are either the colliers or persons hired
on purpose. This method is used in several small collieries; but it is
extremely injudicious, exercising the muscular action of a man in the
most unprofitable manner. Instead of men, horses are sometimes yoked to
these basket-hurdles, which are then made to contain from 4 to 6 hundred
weight of coals; but from the magnitude of the friction, this plan
cannot be commended.

An improvement on this system, where men draw the coals, is to place the
basket or corve on a small four-wheeled carriage, called a tram, or to
attach wheels to the corve itself. Thus much more work is performed,
provided the floor be hard; but not on a soft pavement, unless some kind
of wooden railway be laid.

[Illustration: 851]

The transport of coals from the wall-face to the bottom of the shaft,
was greatly facilitated by the introduction of cast-iron railways, in
place of wooden roads, first brought into practice by Mr. John Curr of
Sheffield. The rails are called tram-rails, or plate-rails, consisting
of a plate from 3 to 4 inches broad, with an edge at right angles to it
about two inches and a half high. Each rail is from 3 to 4 feet long,
and is fixed either to cross bearers of iron, called sleepers, or more
usually to wooden bearers. In some collieries, the miners, after working
out the coals, drag them along these railways to the pit bottom; but in
others, two persons called trammers are employed to transport the coals;
the one of whom, in front of the corve, draws with harness; and the
other, called the patter, pushes behind. The instant each corve arrives,
from the wall-face, at a central spot in the system of the railways, it
is lifted from the tram by a crane placed there, and placed on a
carriage called a rolley, which generally holds two corves. Whenever
three or four rolleys are loaded, they are hooked together, and the
rolley driver, with his horse, takes them to the bottom of the
engine-shaft. The rolley horses have a peculiar kind of shafts, commonly
made of iron, named limbers, the purpose of which is to prevent the
carriage from overrunning them. One of these shafts is represented in
_fig._ 851. The hole shown at _a_, passes over an iron peg or stud in
front of the rolley, so that the horse may be quickly attached or
disengaged. By these arrangements the work is carried on with surprising
regularity and despatch.

The power of the engine for drawing the coals up the shaft, is made
proportional to the depth of the pit and the quantity to be raised, the
corves ascending at an average velocity of about 12 feet per second. So
admirable is the modern arrangement of this operation, that the corves
are transported from the wall-faces to the pit bottom, and moved up the
shaft, as fast as the onsetters at the bottom, and the banksmen at the
top, can hook the loaded and empty corves on and off the engine ropes.
Thus 100 corves of coals have been raised every hour up a shaft 100
fathoms deep, constituting a lift of 27 tons per hour, or 324 tons in a
day, or shift of 12 hours. Coals mined in large cubical masses cannot,
however, be so rapidly raised as the smaller coal of the Newcastle
district.

When coals have so great a rise from the pit bottom to the crop that
horses cannot be used on the rolley ways, the corves descend along the
tram-roads, by means of inclined-plane machines, which are moved either
by vertical rope-barrels, or horizontal rope-sheaves. These inclined
planes are frequently divided into successive stages, 200 or 300 yards
long, at the end of each of which is an inclined-plane machine, whereby
the coals are lowered from one level to another.

The wheels of the trams and rolleys vary in diameter from 8 to 16
inches, according to the thickness of the coal. In some, the axles not
only revolve on their journals, but the wheels also revolve on their
axles.

Various forms of machines have been employed for raising the coals out
of the pits. The steam engine with fly-wheel and rope-barrels, is,
however, now preferred in all considerable establishments. When of small
power, they are usually constructed with a fly wheel, and short
fly-wheel shaft, on which there is a small pinion working into the teeth
of a large wheel, fixed upon the rope barrel. Thus the engine may move
with great rapidity, while it imparts an equable slow motion to the
corves ascending in the shaft. When the engines are of great power,
however, they are directly connected with the rope-barrel; some of these
being of such dimensions, that each revolution of the rope-barrel
produces an elevation of 12 yards in the corve. A powerful brake is
usually connected with the circumference of the fly-wheel or
rope-barrel, whereby the brakeman, by applying his foot to the governing
lever of the brake, and by shutting at the same time the steam valves
with his hands, can arrest the corve, or pitch its arrival within a few
inches of the required height of every delivery. An endless chain,
suspended from the bottom to the top of the shaft, has, in a few pits of
moderate depth, been worked by a steam engine, for raising corves in
constant succession; but the practice has not been found hitherto
applicable on the greater scale.

There is a kind of water engines for raising coals, strictly admissible
only in level free pits, where the ascent of the loaded corve is
produced by the descent of a cassoon filled with water. When the ascent
and descent are through equal spaces, the rope barrels for the cassoon
and the corves are of equal diameter; but when the point from which the
coals have to be lifted is deeper than the point of discharge for the
water into the dry level, the cassoon must be larger, and the rope
barrel smaller; so that by the time the cassoon reaches to the
half-depth, for example, the corve may have mounted through double the
space. The cassoon is filled with water at the pit mouth, and is emptied
by a self-acting valve whenever it gets to the bottom. The loaded corve
is replaced by an empty one at the pit mouth, and its weight, with that
of the descending rope, pull up the empty cassoon; the motions of the
whole mechanism being regulated by a powerful brake.

Various plans have been devised to prevent collision between the
ascending and descending corves, which sometimes pass each other with a
joint velocity of 20 or 30 feet per second. One method is by dividing
the pit from top to bottom, so that each corve moves in a separate
compartment. Another mode was invented by Mr. Curr of Sheffield, in
which wooden guides were attached from top to bottom of the pit; being
spars of deal about 4 inches square, attached perpendicularly to the
sides of the shaft, and to buntons in the middle of the pit. Betwixt
these guides, friction-roller sliders are placed, attached to the
gin-ropes, to which sliders the corves are suspended. In this way, the
corves can be raised with great rapidity; but there is a considerable
loss of time in banking the corve at the pit mouth, where shutters or
sliding boards must be used. This plan is highly beneficial where the
coals are in large lumps.

Both ropes and chains are used for lifting coals. The round ropes are
shroud-laid; but the preferable rope is the flat band, made of four
ropes placed horizontally together, the ropes being laid alternately
right and left. In this way, the ropes counteract one another in the
twist, hanging like a ribbon down the shaft; and are stitched strongly
together by a small cord. Such rope bands are not only very pliable for
their strength, which protects the heart of the rope from breaking, but
as they lap upon themselves, a simple sheave serves as a rope-barrel.
They possess the additional advantage, that by so lapping, they enlarge
the diameter of the axle in which they coil, and thus make a
compensation mechanically against the increasing length of rope
descending with its corve. Thus the counterpoise chains, used in deep
pits to regulate the descent, have been superseded. See ROPE-SPINNING.

When chains are preferred to ropes, as in very deep pits, the short
pudding-link chains are mostly used. See CABLE.

The corves after being landed or banked at the pit mouth, are drawn to
the bin or coal-hill, either upon slips by horses, or by trammers on a
tram-road. But with small coals, like the Newcastle, the pit head is
raised 8 or 9 feet above the common level of the ground, and the
coal-heap slopes downwards from that height. As the bins increase,
tram-roads are laid outwards upon them.

I shall now describe the _ventilation_ of coal mines. Into their
furthest recesses, an adequate supply of fresh air must be carried
forwards, for the purposes of respiration, and the combustion of
candles; as also for clearing off the carbonic acid and carburetted
hydrogen gases, so destructive to the miners, who call these noxious
airs, from their most obvious qualities, choke-damp and fire-damp.

Before the steam engine was applied to the drainage of the mines, and
the extraction of the coal, the excavations were of such limited extent,
that when inflammable air accumulated in the foreheads, it was usual in
many collieries to fire it every morning. This was done by fixing a
lighted candle to the end of a long pole, which being extended towards
the roof by a person lying flat on the floor, the gas was fired, and the
blast passed safely over him. If the gas was abundant, the explosive
miner put on a wet jacket, to prevent the fire from scorching him. In
other situations, where the fire-damp was still more copious, the candle
was drawn forwards into it, by a cord passing over a catch at the end of
the gallery, while the operator stood at a distance. This very rude and
dangerous mode of exploding the inflammable gas, is still practised in a
few mines, under the name of the firing line.

The carbonic acid or choke-damp having a greater specific gravity than
atmospheric air, in the proportion of about 3 to 2, occupies the lower
part of the workings, and gives comparatively little annoyance. Its
presence may moreover be always safely ascertained by the lighted
candle. This cannot, however, be said of the fire-damp, which being
lighter and more movable, diffuses readily through the atmospheric air,
so as to form a most dangerous explosive mixture, even at a considerable
distance from the blowers or sources of its extrication from the coal
strata. Pure subcarburetted hydrogen has a specific gravity = 0·555, air
being 1; and consists of a volume of vapour of carbon, and two volumes
of hydrogen, condensed by mutual affinity into one volume. The
choke-damp is a mixture of the above, with a little carbonic acid gas,
and variable proportions of atmospheric air. As the pure subcarburetted
hydrogen requires twice its bulk of oxygen to consume it completely, it
will take for the same effect about 10 times its bulk of atmospheric
air, since this volume of air contains about two volumes of oxygen. Ten
volumes of air, therefore, mixed with one volume of subcarburetted
hydrogen, form the most powerfully explosive mixture. If either less or
more air be intermixed, the explosive force will be impaired; till 3
volumes of air below or above that ratio, constitute non-explosive
mixtures; that is, 1 of the pure fire-damp mixed with either 7 or 13 of
air, or any quantity below the first, or above the second number, will
afford an unexplosive mixture. With the first proportion, a candle will
not burn; with the second, it burns with a very elongated blue flame.
The fire-damp should therefore be still further diluted with common air,
considerably beyond the above proportion of 1 to 13, to render the
working of the mine perfectly safe.

These noxious gases are disengaged from the cutters, fissures, and
minute pores of the coal; and if the quantity be considerable, relative
to the orifice, a hissing noise is heard.

[Illustration: 852]

Though the choke-damp, or carbonic acid gas, be invisible, yet its line
of division from the common air is distinctly observable on approaching
a lighted candle to the lower level, where it accumulates, which becomes
extinguished the instant it comes within its sphere, as if it were
plunged in water. The stratum of carbonic acid sometimes lies 1 or 2
feet thick on the floor, while the superincumbent air is perfectly good.
When the coal has a considerable dip and rise, the choke-damp will be
found occupying the lower parts of the mine, in a wedge form, as
represented in _fig._ 852., where _a_ shows the place of the carbonic
acid gas, and _b_ that of the common air.

When a gallery is driven in advance of the other workings, and a
discharge of this gas takes place, it soon fills the whole mine, if its
direction be in the line of level, and the mine is rendered unworkable
until a supply of fresh air is introduced to dislodge it. As the flame
of a candle indicates correctly the existence of the choke-damp, the
miners may have sufficient warning of its presence, so as to avoid the
place which it occupies, till adequate means be taken to drive it away.

The fire-damp is not an inmate of every mine, and is seldom found,
indeed, where the carbonic acid prevails. It occurs in the greatest
quantities in the coal mines of the counties of Northumberland, Durham,
Cumberland, Staffordshire, and Shropshire. It is more abundant in coals
of the caking kind, with a bright steel-grained fracture, than in cubic
coals of an open-burning quality. Splint coals are still less liable to
disengage this gas. In some extensive coal-fields it exists copiously on
one range of the line of bearing, while on the other range, none of it
is observed, but abundance of carbonic acid gas.

In the numerous collieries in the Lothians, south from the city of
Edinburgh, the fire-damp is unknown; while in the coal-fields round the
city of Glasgow, and along the coast of Ayrshire, it frequently appears.

[Illustration: 853]

The violent discharge of the gas from a crevice or cutter of the coal,
is called a blower; and if this be ignited, it burns like an immense
blowpipe, inflaming the coal at the opposite side of the gallery. The
gas evidently exists in a highly compressed and elastic state; whence it
seems to loosen the texture of the coals replete with it, and renders
them more easily worked. The gas is often peculiarly abundant near a
great dislocation or slip of the strata; so that the fissure of the
dislocation will sometimes emit a copious stream of gas for many years.
It has also happened, that from certain coals, newly worked, and let
fall from a height into the hold of a vessel, so much inflammable gas
has been extricated that, after the hatches were secured, and the ship
ready to proceed to sea, the gas has ignited with the flame of a candle,
so as to scorch the seamen, to blow up the decks, and otherwise damage
the vessel. In like manner, when the pillars in a mine are crushed by
sudden pressure, a great discharge of gas ensues. This gas being lighter
than common air, always ascends to the roof or to the rise of the
galleries; and, where the dip is considerable, occupies the forehead of
the mine, in a wedge form, as shown in _fig._ 853., where _a_ represents
the fire-damp, and _b_ the common air. In this case, a candle will burn
without danger near the point _c_, close to the floor; but if it be
advanced a few feet further towards the roof, an explosion will
immediately ensue; since at the line where the two elastic fluids are in
contact, they mix, and form an explosive body.

[Illustration: 854]

When this gas is largely diluted with air, the workmen do not seem to
feel any inconvenience from breathing the mixture for a period of many
years; but on inhaling pure carburetted hydrogen, the miner instantly
drops down insensible, and, if not speedily removed into fresh air, he
dies. The production of these noxious gases renders ventilation a
primary object in the system of mining. The most easily managed is the
carbonic acid. If an air-pipe has been carried down the engine pit for
the purpose of ventilation in the sinking, other pipes are connected
with it, and laid along the pavement, or are attached to an angle of the
mine next the roof. These pipes are prolonged with the galleries, by
which means the air at the forehead is drawn up the pipes and replaced
by atmospheric air, which descends by the shaft in an equable current,
regulated by the draught of the furnace at the pit mouth. This
circulation is continued till the miners cut through upon the second
shaft, when the air-pipes become superfluous; for it is well known that
the instant such communication is made, as is represented in _fig._
854., the air spontaneously descends in the engine pit A, and, passing
along the gallery _a_, ascends in a steady current in the second pit B.
The air, in sinking through A, has at first the atmospheric temperature,
which in winter may be at or under the freezing point of water; but its
temperature increases in passing down through the relatively warmer
earth, and ascends in the shaft B, warmer than the atmosphere. When
shafts are of unequal depths, as represented in the figure, the current
of air flows pretty uniformly in one direction. If the second shaft has
the same depth with the first, and the bottom and mouth of both be in
the same horizontal plane, the air would sometimes remain at rest, as
water would do in an inverted syphon, and at other times would circulate
down one pit and up another, not always in the same direction, but
sometimes up the one, and sometimes up the other, according to the
variations of temperature at the surface, and the barometrical
pressures, as modified by winds. There is in mines a proper heat,
proportional to their depth, increasing about one degree of Fahrenheit’s
scale for every 60 feet of descent.

[Illustration: 855]

There is a simple mode of conducting air from the pit bottom to the
forehead of the mine, by cutting a ragglin, or trumpeting, as it is
termed, in the side of the gallery, as represented in _fig._ 855., where
A exhibits the gallery in the coal, and B the ragglin, which is from 15
to 18 inches square. The coal itself forms three sides of the air-pipe,
and the fourth is composed of thin deals applied air-tight, and nailed
to small props of wood fixed between the top and bottom of the lips of
the ragglin. This mode is very generally adopted in running galleries of
communication, and dip-head level galleries, where carbonic acid
abounds, or when from the stagnation of the air the miners’ lights burn
dimly.

When the ragglin or air-pipes are not made spontaneously active, the air
is sometimes impelled through them by means of ventilating fanners,
having their tube placed at the pit bottom, while the vanes are driven
with great velocity by a wheel and pinion worked with the hand. In other
cases, large bellows like those of the blacksmith, furnished with a wide
nozzle, are made to act in a similar way with the fanners. But these are
merely temporary expedients for small mines. A very slight circulation
of air can be effected by propulsion, in comparison of what may be done
by exhaustion; and hence it is better to attach the air-pipe to the
valve of the bellows, than to their nozzle.

Ventilation of collieries has been likewise effected on a small scale,
by attaching a horizontal funnel to the top of air-pipes elevated a
considerable height above the pit mouth. The funnel revolves on a pivot,
and by its tail-piece places its mouth so as to receive the wind. At
other times, a circulation of air is produced by placing coal-fires in
iron grates, either at the bottom of an upcast pit, or suspended by a
chain a few fathoms down.

[Illustration: 856]

Such are some of the more common methods practised in collieries of
moderate depth, where carbonic acid abounds, or where there is a total
stagnation of air. But in all great coal mines the aërial circulation is
regulated and directed by double doors, called main or bearing doors.
These are true air-valves, which intercept a current of air moving in
one direction from mixing with another moving in a different direction.
Such valves are placed on the main roads and passages of the galleries,
and are essential to a just ventilation. Their functions are represented
in the annexed _fig._ 856., where A shows the downcast shaft, in which
the aerial current is made to descend; B is the upcast shaft, sunk
towards the rise of the coal; and C, the dip-head level. Were the mine
here figured to be worked without any attention to the circulation, the
air would flow down the pit A, and proceed in a direct line up the rise
mine to the shaft B, in which it would ascend. The consequence would
therefore be, that all the galleries and boards to the dip of the pit A,
and those lying on each side of the pits, would have no circulation of
air; or, in the language of the collier, would be laid dead. To obviate
this result, double doors are placed in three of the galleries adjoining
the pit; viz., at _a_ and _b_, _c_ and _d_, _e_ and _f_; all of which
open inwards to the shaft A. By this plan, as the air is not suffered to
pass directly from the shaft A to the shaft B, through the doors _a_
and _b_, it would have taken the next shortest direction by _c d_ and _e
f_; but the doors in these galleries prevent this course, and compel it
to proceed downwards to the dip-head level C, where it will spread or
divide, one portion pursuing a route to the right, another to the left.
On arriving at the boards _g_ and _h_, it would have naturally ascended
by them; but this it cannot do, by reason of the building or stopping
placed at _g_ and _h_. By means of such stoppings placed in the boards
next the dip-head level, the air can be transported to the right hand or
to the left for many miles, if necessary, providing there be a train or
circle of aerial communication from the pit A to the pit B. If the
boards _i_ and _k_ are open, the air will ascend in them, as traced out
by the arrows; and after being diffused through the workings, will again
meet in a body at _a_, and mount the gallery to the pit B, sweeping away
with it the deleterious air which it meets in its path. Without double
doors on each main passage, the regular circulation of the air would be
constantly liable to interruptions and derangements; thus, suppose the
door _c_ to be removed, and only _d_ to remain in the left hand gallery,
all the other doors being as represented, it is obvious, that whenever
the door _d_ is opened, the air, finding a more direct passage in that
direction, would mount by the nearest channel _l_, to the shaft B, and
lay dead all the other parts of the work, stopping all circulation. As
the passages on which the doors are placed constitute the main roads by
which the miners go to and from their work, and as the corves are also
constantly wheeling along all the time, were a single door, such as _d_,
so often opened, the ventilation would be rendered precarious or
languid. But the double doors obviate this inconvenience; for both men
and horses, with the corves, in going to or from the pit bottom A, no
sooner enter the door _d_, than it shuts behind them, and encloses them
in the still air contained between the doors _d_ and _c_; _c_ having
prevented the air from changing its proper course while _d_ was open.
When _d_ is again shut, the door _c_ may be opened without
inconvenience, to allow the men and horses to pass on to the pit bottom
at A; the door _d_ preventing any change in the aerial circulation while
the door _c_ is open. In returning from the pit, the same rule is
observed, of shutting one of the double doors, before the other is
opened.

If this mode of disjoining and insulating air-courses from each other be
once fairly conceived, the continuance of the separation through a
working of any extent, may be easily understood.

When carbonic acid gas abounds, or when the fire-damp is in very small
quantity, the air may be conducted from the shaft to the dip-head level,
and by placing stoppings of each room next the level, it may be carried
to any distance along the dip-head levels; and the furthest room on each
side being left open, the air is suffered to diffuse itself through the
wastes, along the wall faces, and mount in the upcast pit, as is
represented in _fig._ 842. But should the air become stagnant along the
wall faces, stoppings are set up throughout the galleries, in such a way
as to direct the main body of fresh air along the wall faces for the
workmen, while a partial stream of air is allowed to pass through the
stoppings, to prevent any accumulation of foul air in the wastes.

In very deep and extensive collieries more elaborate arrangements for
ventilation are introduced. Here the circulation is made active by
rarefying the air at the upcast shaft, by means of a very large furnace
placed either at the bottom or top of the shaft. The former position is
generally preferred. _Fig._ 834. exhibits a furnace placed at the top of
the pit. When it surmounts a single pit, or a single division of the
pit, the compartment intended for the upcast is made air-tight at top,
by placing strong buntons or beams across it, at any suitable distance
from the mouth. On these buntons a close scaffolding of plank is laid,
which is well plastered or moated over with adhesive plastic clay. A
little way below the scaffold, a passage is previously cut, either in a
sloping direction, to connect the current of air with the furnace, or it
is laid horizontally, and then communicates with the furnace by a
vertical opening. If any obstacle prevent the scaffold from being
erected within the pit, this can be made air-tight at top, and a brick
flue carried thence along the surface to the furnace.

The furnace has a size proportional to the magnitude of the ventilation,
and the chimneys are either round or square, being from 50 to 100 feet
high, with an inside diameter of from 5 to 9 feet at bottom, tapering
upwards to a diameter of from 2-1/2 feet to 5 feet. Such stalks are made
9 inches thick in the body of the building, and a little thicker at
bottom, where they are lined with fire-bricks.

The plan of placing the furnace at the bottom of the pit is, however,
more advantageous, because the shaft through which the air ascends to
the furnace at the pit mouth, is always at the ordinary temperature; so
that whenever the top furnace is neglected, the circulation of air
throughout the mine becomes languid, and dangerous to the workmen;
whereas, when the furnace is situated at the bottom of the shaft, its
sides get heated, like those of a chimney, through its total length, so
that though the heat of the furnace be accidentally allowed to decline
or become extinct for a little, the circulation will still go on, the
air of the upcast pit being rarefied by the heat remaining in the sides
of the shaft.

[Illustration: 857 858]

To prevent the annoyance to the onsetters at the bottom, from the hot
smoke, the following plan has been adopted, as shown in the wood-cut,
_fig._ 857., where _a_ represents the lower part of the upcast shaft;
_b_, the furnace, built of brick, arched at top, with its sides
insulated from the solid mass of coal which surrounds it. Between the
furnace wall and the coal-beds, a current of air constantly passes
towards the shaft, in order to prevent the coal catching fire. From the
end of the furnace a gallery is cut in a rising direction at _c_, which
communicates with the shaft at _d_, about 7 or 8 fathoms from the bottom
of the pit. Thus the furnace and furnace-keeper are completely disjoined
from the shaft; and the pit bottom is not only free from all
encumbrances, but remains comfortably cool. To obviate the
inconveniences from the smoke to the banksmen in landing the coals at
the pit mouth, the following plan has been contrived for the Newcastle
collieries. _Fig._ 858. represents the mouth of the pit; _a_ is the
upcast shaft, provided with a furnace at bottom; _b_, the downcast
shaft, by which the supply of atmospheric air descends; and _d_, the
brattice carried above the pit mouth. A little way below the
settle-boards, a gallery _c_, is pushed, in communication with the
surface from the downcast shaft, over which a brick tube or chimney is
built from 60 to 80 feet high, 7 or 8 feet diameter at bottom, and 4 or
5 feet diameter at top. On the top of this chimney a deal funnel is
suspended horizontally on a pivot, like a turn-cap. The vane _f_, made
also of deal, keeps the mouth of the funnel always in the same direction
with the wind. The same mechanism is mounted at the upcast shaft _a_,
only here the funnel is made to present its mouth in the wind’s eye. It
is obvious from the figure, that a high wind will rather aid than check
the ventilation by this plan.

The principle of ventilation being thus established, the next object in
opening up a colliery, and in driving all galleries whatever, is the
_double mine_ or double _headways course_; on the simple but very
ingenious distribution of which, the circulation of air depends at the
commencement of the excavations.

[Illustration: 859]

The double headways course is represented in _fig._ 859., where _a_ is
the one heading or gallery, and _b_ the other; the former being
immediately connected with the upcast side of the pit _c_, and the
latter with the downcast side of the pit _d_. The pit itself is made
completely air-tight by its division of deals from top to bottom, called
the brattice wall; so that no air can pass through the brattice from _d_
to _c_, and the intercourse betwixt the two currents of air is
completely intercepted by a stopping betwixt the pit bottom and the end
of the first pillar of coal; the pillars or walls of coal, marked _e_,
are called stenting walls; and the openings betwixt them, walls or
thirlings. The arrows show the direction of the air. The headings _a_
and _b_ are generally made about 9 feet wide, the stenting walls 6 or 8
yards thick, and are holed or thirled at such a distance as may be most
suitable for the state of the air. The thirlings are 5 feet wide.

When the headings are set off from the pit bottom, an aperture is left
in the brattice at the end of the pillar next the pit, through which the
circulation betwixt the upcast and downcast pits is carried on; but
whenever the workmen cut through the first thirling No. 1., the aperture
in the brattice at the pit bottom is shut; in consequence of which the
air is immediately drawn by the power of the upcast shaft through that
thirling as represented by the dotted arrow. Thus a direct stream of
fresh air is obviously brought close to the forehead where the mines are
at work. The two headings _a_ and _b_ are then advanced, and as soon as
the thirling No. 2. is cut through, a wall of brick and mortar, 4-1/2
inches thick, is built across the thirling No. 1. This wall is termed a
stopping; and being air-tight, it forces the whole circulation through
the thirling No. 2. In this manner the air is always led forward, and
caused to circulate always by the last-made thirling next the forehead;
care being had, that whenever a new thirling is made, the last thirling
through which the air was circulated, be secured with an air-tight
stopping. In the woodcut, the stoppings are placed in the thirlings
numbered 1, 2, 3, 4, 5, 6, and of consequence the whole circulation
passes through the thirling No. 7., which lies nearest the foreheads of
the headings _a_, _b_. By inspecting the figure, we observe, that on
this very simple plan, a stream of air may be circulated to any required
distance, and in any direction, however tortuous. Thus, for example, if
while the double headways course _a_, _b_, is pushed forward, other
double headways courses are required to be carried on at the same time
on both sides of the first headway, the same general principles have
only to be attended to as shown in _fig._ 860., where _a_ is the
upcast, and _b_ the downcast shaft. The air advances along the heading
_c_, but cannot proceed further in that direction than the pillar _d_,
being obstructed by the double doors at _e_. It therefore advances in
the direction of the arrows to the foreheads at _f_, and passing through
the last thirling made there, returns to the opposite side of the double
doors, ascends now the heading _g_ to the foreheads at _h_, passes
through the last-made thirling at that point, and descends, in the
heading _i_, till it is interrupted by the double doors at _k_. The
aerial current now moves along the heading _l_, to the foreheads at _m_,
returns by the last-made thirling there, along the heading _n_, and
finally goes down the heading _o_, and mounts by the upcast shaft _a_,
carrying with it all the noxious gases which it encountered during its
circuitous journey. This wood-cut is a faithful representation of the
system by which collieries of the greatest extent are worked and
ventilated. In some of these, the air courses are from 30 to 40 miles
long. Thus the air conducted by the medium of a shaft divided by a
brattice wall only a few inches thick, after descending in the downcast
in one compartment of the pit at 6 o’clock in the morning, must thence
travel through a circuit of nearly 30 miles, and cannot arrive at its
reascending compartment on the other side of the brattice, or pit
partition, till 6 o’clock in the evening, supposing it to move all the
time at the rate of 2-1/2 miles per hour. Hence we see that the _primum
mobile_ of this mighty circulation, the furnace, must be carefully
looked after, since its irregularities may affect the comfort, or even
the existence of hundreds of miners spread over these vast subterraneous
labyrinths. On the principles just laid down, it appears, that if any
number of boards be set off from any side of these galleries, either in
a level, dip, or rise direction, the circulation of air may be advanced
to each forehead, by an ingoing and returning current.

[Illustration: 860]

Yet while the circulation of fresh air is thus advanced to the last-made
thirling next the foreheads _f_, _h_, and _m_, _fig._ 860., and moves
through the thirling which is nearest to the face of every board and
room, the emission of fire-damp is frequently so abundant from the coaly
strata, that the miners dare not proceed forwards more than a few feet
from that aerial circulation, without hazard of being burned by the
combustion of the gas at their candles. To guard against this accident,
temporary shifting brattices are employed. These are formed of deal,
about 3/4 of an inch thick, 3 or 4 feet broad, and 10 feet long; and are
furnished with cross-bars for binding the deals together, and a few
finger loops cut through them, for lifting them more expeditiously, in
order to place them in a proper position. Where inflammable air abounds,
a store of such brattice deals should be kept ready for emergencies.

[Illustration: 861]

The mode of applying these temporary brattices, or deal partitions, is
shown in the accompanying figure (_fig._ 861.), which shows how the air
circulates freely through the thirling _d_, _d_ before the brattices are
placed. At _b_ and _c_, we see two heading boards or rooms, which are so
full of inflammable air as to be unworkable. Props are now erected near
the upper end of the pillar _e_, betwixt the roof and pavement, about
two feet clear of the sides of the next pillar, leaving room for the
miner to pass along between the pillar side and the brattice. The
brattices are then fastened with nails to the props, the lower edge of
the under brattice resting on the pavement, while the upper edge of the
upper is in contact with the roof. By this means any variation of the
height in the bed of coal is compensated by the overlap of the brattice
boards; and as these are advanced, shifting brattices are laid close to,
and alongside of, the first set. The miner next sets up additional props
in the same parallel line with the former, and slides the brattices
forwards, to make the air circulate close to the forehead where he is
working; and he regulates the distance betwixt the brattice and the
forehead by the disengagement of fire-damp and the velocity of the
aerial circulation. The props are shown at _d d_, and the brattices at
_f_, _f_. By this arrangement the air is prevented from passing directly
through the thirling _a_, and is forced along the right-hand side of the
brattice, and, sweeping over the wall face or forehead, returns by the
back of the brattice, and passes through the thirling _a_. It is
prevented, however, from returning in its former direction by the
brattice planted in the forehead _c_, whereby it mounts up and
accomplishes its return close to that forehead. Thus headways and boards
are ventilated till another thirling is made at the upper part of the
pillar. The thirling _a_ is then closed by a brick stopping, and the
brattice boards removed forward for a similar operation.

[Illustration: 862]

When blowers occur in the roof, and force the strata down, so as to
produce a large vaulted excavation, the accumulated gas must be swept
away; because, after filling that space, it would descend in an unmixed
state under the common roof of the coal. The manner of removing it is
represented in _fig._ 862., where _a_ is the bed of coal, _b_ the
blower, _c_ the excavation left by the downfall of the roof, _d_ is a
passing door, and _e_ a brattice. By this arrangement the aerial current
is carried close to the roof, and constantly sweeps off or dilutes the
inflammable gas of the blower, as fast as it issues. The arrows show the
direction of the current; but for which, the accumulating gas would be
mixed in explosive proportions with the atmospheric air, and destroy the
miners.

[Illustration: 863]

There is another modification of the ventilating system, where the
air-courses are traversed across; that is, when one air-course is
advanced at right angles to another, and must pass it in order to
ventilate the workings on the further side. This is accomplished on the
plan shown in _fig._ 863., where _a_ is a main road with an air-course,
over which the other air-course _b_, has to pass. The sides of this air
channel are built of bricks arched over so as to be air-tight, and a
gallery is driven in the roof strata as shown in the figure. If an
air-course, as _a_, be laid over with planks made air-tight, crossing
and recrossing may be effected with facility. The general velocity of
the air in these ventilating channels is from 3 to 4 feet per second, or
about 2-1/2 miles per hour, and their internal dimensions vary from 5 to
6 feet square, affording an area of from 25 to 36 square feet.

[Illustration: 864]

Mr. Taylor’s hydraulic air-pump, formerly described, p. 839., deserves
to be noticed among the various ingenious contrivances for ventilating
mines, particularly when they are of moderate extent. _a_ is a large
wooden tub, nearly filled with water, through whose bottom the
ventilating pipe _b_ passes down into the recesses of the mine. Upon the
top of _b_, there is a valve _e_, opening upwards. Over _b_, the
gasometer vessel is inverted in _a_, having a valve also opening
outwards at _d_. When this vessel is depressed by any moving force, the
air contained within it is expelled through _d_; and when it is raised,
it diminishes the atmospherical pressure in the pipe _b_, and thus draws
air out of the mine into the gasometer; which cannot return on account
of the valve at _e_, but is thrown out into the atmosphere through _d_
at the next descent.

The general plan of distributing the air, in all cases, is to send the
first of the current that descends in the downcast shaft among the
horses in the stables, next among the workmen in the foreheads, after
which the air, loaded with whatever mixtures it may have received, is
made to traverse the old wastes. It then passes through the furnace with
all the inflammable gas it has collected, ascends the upcast shaft, and
is dispersed into the atmosphere. This system, styled _coursing the
air_, was invented by Mr. Spedding of Cumberland. According to the
quantity of the fire-damp, the coursing is conducted either up one room,
and returned by the next alternately, through the whole extent of the
works, or it passes along 2 or 3 connected rooms, and returns by the
same number.

[Illustration: 865]

This admirable system has received the greatest improvements from the
mining engineers of the Newcastle district, and especially from Mr.
Buddle of Wallsend. His plan being a most complete scale of ventilation,
where the aerial current is made to sweep every corner of the workings,
is shown in _fig._ 865.; in which _a_ represents the downcast, and _b_
the upcast shaft. By pursuing the track of the arrows, we may observe
that the air passes first along the two rooms _c_, _d_, having free
access to each through the walls, but is hindered from entering into the
adjoining rooms by the stoppings which form the air-courses. It sweeps
along the wall faces of the rooms _c_, _d_, and makes a return down the
rooms _e_, _f_, but is not allowed to proceed further in that direction
by the stoppings _g_, _h_. It then proceeds to the foreheads _i_, _k_,
and single courses all the rooms to the foreheads _l_, _m_; from this
point it would go directly to the upcast pit _b_, were it not prevented
by the stopping _n_, which throws it again into double coursing the
rooms, till it arrives at _o_, whence it goes directly to the furnace,
and ascends the shaft _b_. The lines across each other represent the
passing doors; and these may be substituted in any place for a passage
where there is a stopping. The stopping _p_, near the bottom of the
downcast shaft, is termed a main stopping; because if it were removed,
the whole circulation would instantly cease, and the air, instead of
traversing in the direction of the arrows, would go directly from the
downcast pit _a_, to the upcast pit _b_, along the gallery _q_. Hence
every gallery and room of the workings would be laid _dead_, as it is
termed, and be immediately filled with fire-damp, which might take fire
either at the workmen’s candles, or at the furnace next the upcast shaft
_b_. Thus also a partial stagnation in one district of the colliery,
would be produced by any of the common stoppings being accidentally
removed or destroyed, since the air would thereby always pursue the
nearest route to the upcast pit. Main stoppings are made particularly
secure, by strong additional stone buildings, and they are set up at
different places, to maintain the main air courses entire in the event
of an explosion; by which precautions great security is given to human
life. This system of ventilation may be extended to almost any distance
from the pit-bottom, provided the volume of fresh air introduced be
adequate to dilute sufficiently the fire-damp, so that the mixture shall
not reach the explosive point. The air, by this management, ventilates
first one panel of work, and then other panels in succession, passing
onwards through the barriers or panel walls, by means of galleries, as
in _fig._ 843., by the principle either of single, double, or triple
coursing, according to the quantity of gas in the mine.

In ventilating the very thick coal of Staffordshire, though there is
much inflammable air, less care is needed than in the north of England
collieries, as the workings are very roomy, and the air courses of
comparatively small extent. The air is conducted down one shaft, carried
along the main roads, and distributed into the sides of work, as shown
in _fig._ 848. A narrow gallery, termed the air-head, is carried in the
upper part of the coal, in the rib walls, along one or more of the
sides. In the example here figured, it is carried all round, and the air
enters at the bolt-hole _e_. Lateral openings, named spouts, are led
from the air-head gallery into the side of work; and the circulating
stream mixed with the gas in the workings, enters by these spouts, as
represented by the arrows, and returns by the air-head at _g_, to the
upcast pit.

When the fire-damp comes off suddenly in any case, rendering the air
foul and explosive at the foreheads, if no other remedy be found
effectual, the working of the coal must be suspended, and a current of
air sent directly from the fresh in-going stream, in order to dilute the
explosive mixture, before it reaches the furnace. This is termed
_skailing the air_; for otherwise the gas would kindle at the furnace,
and flame backwards, like a train of gunpowder, through all the windings
of the work, carrying devastation and death in its track. By _skailing_
the air, however, time is given for running forward with water, and
drowning the furnace. A cascade of water from the steam engine pumps is
then allowed to fall down the pit, the power of which through a fall of
500 or 600 feet, is so great in carrying down a body of air, that it
impels a sufficient current through every part of the workings. The
ventilation is afterwards put into its usual train at leisure.

In collieries which have been worked for a considerable time, and
particularly in such as have goaves, creeps, or crushed wastes, the
disengagement of the fire-damp from these recesses is much influenced by
the state of atmospheric pressure. Should this be suddenly diminished,
as shown by the fall of the barometer, the fire-damp suddenly expands
and comes forth from its retirement, polluting the galleries of the mine
with its noxious presence. But an increase of barometric pressure
condenses the gases of the mine, and restrains them within their
sequestered limits. It is therefore requisite that the coal-viewer
should consult the barometer before inspecting the subterraneous
workings of an old mine, on the Monday mornings, in order to know what
precautions must be observed in his personal survey.

The catastrophe of an explosion in an extensive coal-mine is horrible in
the extreme. Let us imagine a mine upwards of 100 fathoms deep, with the
workings extended to a great distance under the surrounding country,
with machinery complete in all its parts, the mining operations under
regular discipline, and railways conducted through all its
ramifications; the stoppings, passing doors, brattices, and the entire
economy of the mine, so arranged that every thing moves like a well
regulated machine. A mine of this magnitude at full work is a scene of
cheering animation, and happy industry; the sound of the hammer resounds
in every quarter, and the numerous carriages, loaded or empty, passing
swiftly to and fro from the wall faces to the pit bottom, enliven the
gloomiest recesses. At each door a little boy, called a trapper, is
stationed, to open, and shut it. Every person is at his post, displaying
an alacrity and happiness pleasingly contrasted with the surrounding
gloom. While things are in this merry train, it has but too frequently
happened that from some unforeseen cause, the ventilation has partially
stagnated, allowing a quantity of the fire-damp to accumulate in one
space to the explosive pitch; or a blower has suddenly sprung forth, and
the unsuspecting miner entering this fatal region with his candle, sets
the whole in a blaze of burning air, which immediately suffocates and
scorches to death every living creature within its sphere, while
multitudes beyond the reach of the flame are dashed to pieces by the
force of the explosion, rolling like thunder along the winding
galleries. Sometimes the explosive flame seems to linger in one
district for a few moments; then gathering strength for a giant effort,
it rushes forth from its cell with the violence of a hurricane, and the
speed of lightning, destroying every obstacle in its way to the upcast
shaft. Its power seems to be irresistible. The stoppings are burst
through, the doors are shivered into a thousand pieces; while the
unfortunate miners, men, women, and boys, are swept along with an
inconceivable velocity, in one body, with the horses, carriages, corves,
and coals. Should a massive pillar obstruct the direct course of the
aerial torrent, all these objects are dashed against it, and there
prostrated or heaped up in a mass of common ruin, mutilation, and death.
Others are carried directly to the shaft, and are either buried there
amid the wreck, or are blown up and ejected from the pit mouth. Even at
this distance from the explosive den, the blast is often so powerful,
that it frequently tears the brattice walls of the shaft to pieces, and
blows the corves suspended in the shaft as high up into the open air as
the ropes will permit. Not unfrequently, indeed, the ponderous
pulley-wheels are blown from the pit-head frame, and carried to a
considerable distance in the bosom of a thick cloud of coals and
coal-dust brought up from the mine by the fire-damp, whose explosion
shakes absolutely the superincumbent solid earth itself with a mimic
earthquake. The dust of the ruins is sometimes thrown to such a height
above the pit as to obscure the light of the sun. The silence which
succeeds to this awful turmoil is no less formidable; for the
atmospheric back-draught, rushing down the shaft, denotes the
consumption of vital air in the mine, and the production of the
deleterious choke-damp and azote.

Though many of the miners may have escaped by their distance in the
workings from the destructive blast and the fire, yet their fate may
perhaps be more deplorable. They hear the explosion, and are well aware
of its certain consequences. Every one anxious to secure his personal
safety, strains every faculty to reach the pit-bottom. As the lights are
usually extinguished by the explosion, they have to grope their way in
utter darkness. Some have made most marvellous escapes, after clambering
over the rubbish of fallen roofs, under which their companions are
entombed; but others wandering into uncertain alleys, tremble lest they
should encounter the pestilential airs. At last they feel their power,
and aware that their fate is sealed, they cease to struggle with their
inevitable doom; they deliberately assume the posture of repose, and
fall asleep in death. Such has been too often the fate of the hardy and
intelligent miners who immure themselves deep beneath the ground, and
venture their lives for the comfort of their fellow-men; and such
frequently is the ruinous issue of the best ordered and most prosperous
mining concerns.

In such circumstances the mining engineers or coal viewers have a
dangerous and difficult duty to perform. The pit into which they must
descend as soon as possible, is rendered unsafe by many causes; by the
wrecks of loose timber torn away by the eruption, or by the unrespirable
gases; by the ignition perhaps of a portion of the coal itself, or by
the flame of a blower of fire-damp; either of which would produce
violent and repeated explosions whenever the gas may again accumulate to
the proper degree. Such a predicament is not uncommon, and it is one
against which no human skill can guard. Yet even here, the sense of
duty, and the hope of saving some workmen from a lingering death by
wounds or suffocation, lead this intrepid class of men to descend amid
the very demons of the mine.

As soon as the ventilation is restored by temporary brattices, the
stoppings and doors are rebuilt in a substantial manner, and the
workings are resumed with the wonted activity. From an inspection of
_fig._ 864., p. 1029, it is obvious that the stability of the main
stopping _p_, is an important point; for which reason it is
counterforted by strong walls of stone, to resist the explosive force of
fire-damp.

When it is known that fire exists in the wastes, either by the burning
of the small coal-dust along the roads, or from the ignition of the
solid coal by a blower of gas, the inspection of the mine is
incomparably more hazardous, as safety cannot be insured for an instant;
for if the extrication of gas be great, it rapidly accumulates, and
whenever it reaches the place where the fire exists, a new explosion
takes place. There have been examples of the most furious detonations
occurring regularly after the interval of about an hour, and being thus
repeated 36 times in less than two days, each eruption appearing at the
pit mouth like the blast of a volcano. It would be madness for any one
to attempt a descent in such circumstances. The only resource is to moat
up the pit, and check the combustion by exclusion of atmospheric air, or
to drown the workings by letting the water accumulate below ground.

When fire exists in the wastes, with less apparent risk of life, water
is driven upon it by portable fire-extinguishing engines, or small
cannon are discharged near the burning coal, and the concussion thus
produced in the air sometimes helps to extinguish the flame.

Since the primary cause of these tremendous catastrophes is the
accension of the explosive gases by the candle of the miner, it has been
long a desideratum to procure light of such a nature as may not possess
the power of kindling the fire-damp. The train of light producible from
the friction of flint and steel, by a mechanism called _a steel mill_,
has been long known, and afforded a tolerable gleam, with which the
miners were obliged to content themselves in hazardous atmospheres.

It consists of a small frame of iron, mounted with a wheel and pinion,
which give rapid rotation to a disk of hard steel placed upright, to
whose edge a piece of flint is applied. The use of this machine entailed
on the miner the expense of an attendant, called the miller, who gave
him light. Nor was the light altogether safe, for occasionally the
ignited shower of steel particles attained to a sufficient heat to set
fire to the fire-damp.

At length the attention of the scientific world was powerfully attracted
to the means of lighting the miner with safety, by an awful catastrophe
which happened at Felling Colliery, near Newcastle, on the 25th May,
1812. This mine was working with great vigour, under a well-regulated
system of ventilation, set in action by a furnace and air-tube, placed
over a rise pit in elevated ground. The depth of winning was above 100
fathoms; 25 acres of coal had been excavated, and one pit was yielding
at the rate of 1700 tons per week. At 11 o’clock in the forenoon the
night shift of miners was relieved by the day shift; 121 persons were in
the mine, at their several stations, when, at half-past 11, the gas
fired, with a most awful explosion, which alarmed all the neighbouring
villages. The subterraneous fire broke forth with two heavy discharges
from the dip-pit, and these were instantly followed by one from the
rise-pit. A slight trembling, as from an earthquake, was felt for about
half a mile round the colliery, and the noise of the explosion, though
dull, was heard at from 3 to 4 miles’ distance. Immense quantities of
dust and small coal accompanied these blasts, and rose high into the
air, in the form of an inverted cone. The heaviest part of the ejected
matter, such as corves, wood, and small coal, fell near the pits; but
the dust borne away by a strong west wind fell in a continuous shower a
mile and a half from the pit. In the adjoining village of Heworth it
caused a darkness like that of early twilight, covering the roads where
it fell so thickly that the footsteps of passengers were imprinted in
it. The heads of both shaft-frames were blown off, their sides set on
fire, and their pulleys shattered to pieces. The coal-dust ejected from
the rise-pit into the horizontal part of the ventilating tube, was about
3 inches thick, and speedily burnt to a cinder; pieces of burning coal,
driven off the solid stratum of the mine, were also blown out of this
shaft. Of the 121 persons in the mine at the time of the explosion, only
32 were drawn up the pit alive, 3 of whom died a few hours after the
accident. Thus no less than 92 valuable lives were instantaneously
destroyed by this pestilential fire-damp. The scene of distress among
the relatives at the pit mouth was indescribably sorrowful.

Dr. W. Reid Clanny, of Sunderland, was the first to contrive a lamp
which might burn among explosive air without communicating flame to the
gas in which it was plunged. This he effected, in 1813, by means of an
air-tight lamp, with a glass front, the flame of which was supported by
blowing fresh air from a small pair of bellows through a stratum of
water in the bottom of the lamp, while the heated air passed out through
water by a recurved tube at top. By this means the air within the lamp
was completely insulated from the surrounding atmosphere. This lamp was
the first ever taken into a body of inflammable air in a coal-mine, at
the exploding point, without setting fire to the gas around it. Dr.
Clanny made another lamp upon an improved plan, by introducing into it
the steam of water generated in a small vessel at the top of the lamp,
heated by the flame. The chief objection to these lamps is their
inconvenience in use.

Various other schemes of safe-lamps were offered to the miner by
ingenious mechanicians, but they have been all superseded by the
admirable invention of Sir H. Davy, founded on his fine researches upon
flame. The lamp of Davy was instantly tried and approved of by Mr.
Buddle and the principal mining engineers of the Newcastle district. A
perfect security of accident is therefore afforded to the miner in the
use of a lamp which transmits its light, and is fed with air, through a
cylinder of wire gauze; and this invention has the advantage of
requiring no machinery, no philosophical knowledge to direct its use,
and is made at a very cheap rate.

In the course of a long and laborious investigation on the properties of
the fire-damp, and the nature and communication of flame, Sir H. Davy
ascertained that the explosions of inflammable gases were incapable of
being passed through long narrow metallic tubes; and that this principle
of security was still obtained by diminishing their length and diameter
at the same time, and likewise diminishing their length, and increasing
their number, so that a great number of small apertures would not pass
an explosion, when their depth was equal to their diameter. This fact
led him to trials upon sieves made of wire-gauze, or metallic plates
perforated with numerous small holes; and he found it was impossible to
pass explosions through them.

The apertures in the gauze should never be more than 1-20th of an inch
square. In the working models sent by Sir H. to the mines, there were
748 apertures in the square inch, and the wire was about the 40th of an
inch diameter. The cage or cylinder of wire gauze should be made by
double joinings, the gauze being folded over in such a manner as to
leave no apertures. It should not be more than two inches in diameter;
or in large cylinders the combustion of the fire-damp renders the top
inconveniently hot; and a double top is always a proper precaution,
fixed at a distance of about half an inch above the first top. The gauze
cylinder should be fastened to the lamp by a screw of 4 or 5 turns. All
joinings in the lamp should be made with hard solder; and the security
depends upon the condition, that no aperture exists in the apparatus
larger than in the wire gauze.

The forms of the lamp and cage, and the mode of burning the wick, may be
greatly diversified; but the principle which ensures their safety must
be strictly attended to. See LAMP OF DAVY, SAFETY LAMP, and VENTILATION.

The state of the air in coal mines, from very early periods till the
discovery of the safe-lamp, was judged of by the appearances exhibited
by the flame of a candle; and this test must in many circumstances be
still had recourse to. When there is merely a defect of atmospheric
oxygen, the air being also partially vitiated by a little carbonic acid,
either from choke-damp or the lungs and candles of the miners, the
lights burn with a very dull flame, the tallow ceases to melt in the cup
formed round the wick, till the flame flickers and expires. In this case
the candle may be kept burning by slanting it more or less towards a
horizontal position, which causes the tallow to melt with the edge of
the flame. The candle is thus rapidly wasted, however; and therefore an
oil lamp is preferable, as it continues to burn where a candle would be
extinguished. The candles of the collier are generally small, with a
very small wick; such being found to produce a more distinct flame than
candles of a large size with a thick wick.

In trying the quality of the air by the flame of a candle, the wick must
be trimmed by taking off the snuff, so as to produce a clear, distinct,
and steady-burning flame. When a candle thus trimmed is looked at in
common air, a distinct and well-defined cone of flame is seen, of a fine
sky-blue at the bottom next the wick, and thence of a bright yellow to
the apex of the cone. Besides this appearance, there is another,
surrounding the cone, which the brightness of the flame prevents the eye
from discerning. This may be seen by placing one of the hands expanded
as a screen betwixt the eyes and the candle, and at the distance of
about an inch, so that the least point of the apex of the yellow flame
may be seen, and no more. By this method, a top, as the miners term it,
will be distinctly observed close to the apex of the yellow flame, from
an eighth to a quarter of an inch in length. This top is of a
yellowish-brown colour, and like a misty haze. This haze is seen not
only on the top, but it extends downwards and surrounds the flame fully
half way, about a twentieth of an inch in thickness; here it assumes a
violet colour, which passes into a beautiful blue at the bottom next the
wick. The test of the state of the air in mines, or “trying the candle,”
as practised by miners, depends entirely on the appearance which this
haze assumes in shape and colour at the top of the flame. In fact, this
top has distinct appearances when burning in atmospheric air, carbonated
air, azotized air, or fire-damp air; displaying many modifications,
according to the proportions of the various admixtures.

When azote or carbonic acid abounds, the top is frequently an inch or
two in length, of a decided brown colour, and the flame is short and
dim. When they are still more copious, the flame goes out, and the
miners immediately retire.

When inflammable air is imagined to exist in considerable quantity, the
miner trims his candle, and advances with cautious step, holding the
candle with the left hand, and screening the flame with the right; and
as the fire-damp floats in the upper part of the gallery next the roof,
he holds the candle as low as he can, and keeping his eye fixed on the
tip, he moves forwards. If the gas be small in quantity, he may reach
the forehead without observing any material change in his light. But if
in his advance he perceives the tip to elongate, and take a bluish-gray
colour, he is put on his guard, and steps on with much caution; and if
the tip begins to spire, he drops down on one knee, and holding the
candle near the pavement, gradually raises it up, and watches the change
it undergoes as it approaches the roof. If the gas be copious, the flame
elongates into a sharp spire, as well as the top. It is in general
reckoned dangerous when the tip changes from the bluish-gray to a fine
blue colour, accompanied with minute luminous points, which pass rapidly
upwards through the flame and top. When the symptoms are manifestly
dangerous, a sudden movement of the hands or body is liable to produce
ignition by agitation of the fire-damp. The experienced miner therefore
slowly and cautiously lowers his candle to the pavement, and then
turning round, effects his retreat slowly, or slips up his right hand
and extinguishes the flame with his finger and thumb. Should he venture
too far, and approach the body of gas in an explosive condition, the tip
of the candle rapidly elongates, and the whole rises in a sharp spire
several inches in length; and then the whole surrounding atmosphere is
in a blaze, an explosion ensues, and destructive ravage is the
consequence, to an extent proportioned to the quantity of fire-damp. See
SAFETY LAMP, and VENTILATION.

This _trying the candle_ is a delicate operation, requiring much
practical sagacity, where the lives of so many men, and the welfare of
the whole establishment, are at stake. Almost every colliery, after
having been worked for some time, gives a peculiar top to the candle;
so that while in one mine liable to fire-damp an explosion will take
place with a top less than an inch long, in another mine the top may be
two inches high, and yet the air be considerably under the point of
accension. These differences depend on several particulars. If the gas
has not passed through a long course of ventilation, and is little mixed
with air, it will ignite with a very short top; while on the other hand,
a gas which has run through a ventilation of 20 or 30 miles may cause
the production of a long top without hazard. It is hence obvious, that
skilful experience, and thorough practical knowledge, are the only sure
guides in these cases.

[Illustration: 866 867]

We shall now describe briefly the modern modes of working coals
a-dipping of, and deeper than, the engine-pit bottom. One of these
consists in laying a working pump barrel with a long wind-bore at the
bottom of the downset mine, furnished with a smooth rod working through
a collar at the top of the working barrel. At one side of this, near the
top, a kneed pipe is attached, and from it pipes are carried to the
point of delivery, either at the engine-pit bottom or day level, as
represented in _fig._ 866. The spears are worked sometimes by rods
connected with the machinery at the surface; in which case the spears,
if very long, are either suspended from swing or pendulum rods, or move
on friction rollers. But since the action of the spears, running with
great velocity the total length of the engine stroke, very soon tears
every thing to pieces, the motion of the spears underground has been
reduced from 6 or 8 feet, the length of the engine stroke, to about 15
inches; and the due speed in the pump is effected by the centering of a
beam, and the attachment of the spears to it, as represented in _fig._
867., where _a_ is the working barrel, _b_ the beam centered at _c_,
having an arc-head and martingale sinking-chain. The spears _d_ are
fastened by a strong bolt, which passes through the beam; and there are
several holes, by means of which the stroke in the pumps can be
lengthened or shortened at convenience. The movement of the spears is
regulated by a strong iron quadrant or wheel at the bottom.

In level-free coals, these pumps may be worked by a water-wheel,
stationed near the bottom of the pit, impelled by water falling down the
shaft, to be discharged by the level to the day (day-level).

But the preferable plan of working under-dip coal, is that recently
adopted by the Newcastle engineers; and consists in running a mine
a-dipping of the engine-pit, in such direction of the dip as is most
convenient; and both coals and water are brought up the rise of the coal
by means of high-pressure engines, working with a power of from 30 to 50
pounds on the square inch. These machines are quite under command, and,
producing much power in little space, they are the most applicable for
underground work. An excavation is made for them in the strata above the
coal, and the air used for the furnace under the boiler, is the returned
air of the mine ventilation. In the dip-mine a double tram-road is laid;
so that while a number of loaded corves are ascending, an equal number
of empty ones are going down. Although this improved method has been
introduced only a few years back, under-dip workings have been already
executed more than an English mile under-dip of the engine-pit bottom,
by means of three of these high-pressure engines, placed at equal
distances in the under-dip mine. It may hence be inferred, that this
mode of working is susceptible of most extensive application; and in
place of sinking pits of excessive depth upon the dip of the coal, at an
almost ruinous expense, much of the under-dip coal will in future be
worked by means of the actual engine-pits. In the Newcastle district,
coals are now working in an engine-pit 115 fathoms deep under-dip of the
engine-pit bottom, above 1600 yards, and fully 80 fathoms of
perpendicular depth more than the bottom of the pit.

[Illustration: 868]

If an engine-pit be sunk to a given coal at a certain depth, all the
other coals of the coal-field, both above and below the coal sunk to,
can be drained and worked to the same depth, by driving a level
cross-cut mine, both to the dip and rise, till all the coals are
intersected, as represented in _fig._ 868., where A is the engine-pit
bottom reaching to the coal _a_; and _b_, _c_, _d_, _e_, _f_, coals
lying above the coal _a_; the coals which lie below it, _g_, _h_, _i_;
_k_ is the forehead of the cross-cut mine, intersecting all the lower
coals; and _l_, the other forehead of the mine, intersecting all the
upper coals.

[Illustration: 869

  1. First stage of active creep.
  2. Second do.
  3. Third do.
  4. Fourth do.
  5. The metal ridge closed, and the creep beginning to settle.
  6. The creep settled, the metal ridges being closely compressed, and
     supporting the roof.]

In the “Report from the select committee of the House of Lords,
appointed to take into consideration the state of the coal trade in the
United Kingdom,” printed in June, 1829, under the head of Mr. Buddle’s
evidence we have an excellent description of the nature and progress of
creeps, which we have adverted to in the preceding account. The annexed
_fig._ 869. exhibits the creep in all its progressive stages, from its
commencement until it has completely closed all the workings, and
crushed the pillars of coal. The section of the figures supposes us
standing on the level of the different galleries which are opened in the
seam. The black is the coal pillars between each gallery; when these are
weakened too much, or, in other words, when their bases become too
narrow for the pavement below, by the pressure of the incumbent
stratification they sink down into the pavement, and the first
appearance is a little curvature in the bottom of each gallery: that is
the first symptom obvious to sight; but it may generally be heard before
it is seen. The next stage is when the pavement begins to open with a
crack longitudinally. The next stage is when that crack is completed,
and it assumes the shape of a metal ridge. The next is when the metal
ridge reaches the roof. The next stage is when the peak of the metal
ridge becomes flattened by pressure, and forced into a horizontal
direction, and becomes quite close; just at this moment the coal pillars
begin to sustain part of the pressure. The next is when the coal pillars
take part of the pressure. The last stage is when it is dead and
settled; that is, when the metal or factitious ridge, formed by the
sinking of the pillar into the pavement, bears, in common with the
pillars of coal on each side, the full pressure, and the coal becomes
crushed or cracked, and can be no longer worked, except by a very
expensive and dangerous process. _Fig._ 869.

The quantity of coals, cinders, and culm shipped coastways, and exported
from the several ports of the United Kingdom in the year 1837, was
8,204,301 tons; in 1836, the quantity was 7,389,272 tons, being an
increase of 815,029 tons, or 11·03 per cent. in favour of 1837.

The following TABLE shows the separate proportions of this quantity
supplied by England and Wales, Scotland, and Ireland:--

  +-----------------+---------+---------+--------------------------+
  |                 |  1836.  |  1837.  |        Increase.         |
  +-----------------+---------+---------+--------------------------+
  |                 |  Tons.  |  Tons.  |  Tons.                   |
  |England and Wales|6,757,937|7,570,254|812,317 or 12·02 per cent.|
  |Scotland         |  624,308|  626,532|  2,204     0·36          |
  |Ireland          |    7,027|    7,515|    488     6·94          |
  |                 +---------+---------+--------------------------+
  |        Total    |7,389,272|8,204,301|815,029 or 11·03 per cent.|
  +-----------------+---------+---------+--------------------------+


PITCOAL, COKING OF. See also CHARCOAL.

[Illustration: 870]

_Fig._ 870. represents a _schachtofen_, or pit-kiln, for coking coals in
Germany. _a_ is the lining (_chemise_), made of fire-bricks; the
enclosing walls are built of the same material; _b_, _b_, is a cast-iron
ring covered with a cast-iron plate _c_. The floor of the kiln is
massive. The coals are introduced, and the coke taken out, through a
hole in the side _d_; during the process it is bricked up, and closed
with an iron door. In the surrounding walls are 4 horizontal rows of
flues _e_, _e_, _e_, _e_, which are usually iron pipes; the lowest row
is upon a level with the floor of the kiln; and the others are each
respectively one foot and a half higher than the preceding. Near the top
of the shaft there is an iron pipe _f_, of from 8 to 10 inches in
diameter, which allows the incoercible vapours generated in the coking
to escape into the condenser, which consists either of wood or brick
chambers. For kindling the coal, a layer of wood is first placed on the
bottom of the kiln.

The coking of small coal is performed upon vaulted hearths, somewhat
like bakers’ ovens, but with still flatter roofs. Of such kilns, several
are placed alongside one another each being an ellipse deviating little
from a circle, so that the mouth may project but a small space. The
dimensions are such, that from 10 to 12 cubic feet of coal-culm may be
spread in a layer 6 inches deep upon the sole of the furnace. The top of
the flat arch of fire brick should be covered with a stratum of loam and
sand.

[Illustration: 871 872]

_Figs._ 871. and 872. represent such a kiln as is mounted at Zabrze, in
Upper Silesia, for coking small coal. _Fig._ 871. is the ground plan;
_fig._ 872. the vertical section in the line of the long axis of _fig._
871. _a_, is the sand-bed of the hearth, under the brick sole; _b_, is
the roof of large fire-bricks; _c_, the covering of loam; _d_, the top
surface of sand; _e_, the orifice in the front wall, for admission of
the culm, and removal of the coke, over the sloping stone _f_. The flame
and vapours pass off above this orifice, through the chimney marked _g_,
or through the aperture _h_, into a lateral chimney. _i_, is a bar of
iron laid across the front of the door as a fulcrum to work the iron
rake upon. A layer of coals is first kindled upon the hearth, and when
this is in brisk ignition, it is covered with the culm in successive
sprinklings. When the coal is sufficiently coked, it is raked out, and
quenched with water.

[Illustration: 873 874]

_Fig._ 873. represents a simple coking _meiler_ or _mound_, constructed
in a circular form round a central chimney of loose bricks, towards
which small horizontal flues are laid among the lumps of coals. The
sides and top are covered with culm or slack, and the heap is kindled
from certain openings towards the circumference. _Fig._ 874. represents
an oblong _meiler_, sometimes made 100 or 150 feet in length, and from
10 to 12 in breadth. The section in the middle of the figure shows how
the lumps are piled up; the wooden stakes are lifted out when the heap
is finished, in order to introduce kindlings at various points; and the
rest of the meiler is then covered with slack and clay, to protect it
from the rains. A jet of smoke and flame is seen issuing from its left
end.

[Illustration: 875 876 877]

An excellent range of furnaces for making a superior article of coke,
for the service of the locomotive engines of the London and Birmingham
Railway Company, has been recently erected at the Camden Town station;
consisting of 18 ovens in two lines, the whole discharging their
products of combustion into a horizontal flue, which terminates in a
chimney-stalk, 115 feet high. _Fig._ 875. is a ground plan of the
elliptical ovens, each being 12 feet by 11 internally, and having 3 feet
thickness of walls. _a_, _a_, is the mouth, 3-1/2 feet wide outside,
and about 2-3/4 feet within. _b_, _b_, are the entrances into the flue;
they may be shut more or less completely by horizontal slabs of
fire-brick, resting on iron frames, pushed in from behind, to modify the
draught of air. The grooves of these damper-slabs admit a small stream
of air to complete the combustion of the volatilized particles of soot.
By this means the smoke is well consumed. The flue _c_, _c_, is 2-1/2
feet high, by 21 inches wide. The chimney _d_, at the level of the flue,
is 11 feet in diameter inside, and 17 outside; being built from an
elegant design of Robert Stephenson, Esq. (See CHIMNEY.) _d_, _d_, are
the keys of the iron hoops, which bind the brickwork of the oven. _Fig._
876. is a vertical section in the line A, B, of _fig._ 875. showing, at
_b_, _b_, and _e_, _e_, the entrances of the different ovens into the
horizontal flue; the direction of the draught being indicated by the
arrows. _f_, _f_, is a bed of concrete, upon which the whole
furnace-range is built, the level of the ground being in the middle of
that bed. _g_, is a stauncheon on which the crane is mounted: (see
_fig._ 877.) _h_ is a section of the chimney wall, with part of the
interior to the left of the strong line. _Fig._ 877. is a front
elevation of two of these elegant coke-ovens; in which the bracing hoops
_i_, _i_, _i_, are shown; _k_, _k_, are the cast-iron doors,
strengthened outside with diagonal ridges; each door being 5-1/2 feet
high, by 4 feet wide, and lined internally with fire-bricks. They are
raised and lowered by means of chains and counterweights, moved by the
crane _l_.

Each alternate oven is charged, between 8 and 10 o’clock every morning,
with 3-1/2 tons of good coals. A wisp of straw is thrown in on the top
of the heap, which takes fire by the radiation from the dome (which is
in a state of dull ignition from the preceding operation), and inflames
the smoke then rising from the surface, by the re-action of the hot
sides and bottom upon the body of the fuel. In this way the smoke is
consumed at the very commencement of the process, when it would
otherwise be most abundant. A neighbour of the above coking ovens,
having lately indicted them as a nuisance, procured, _secundum artem_, a
parcel of affidavits from sundry chemical and medical men. Two of the
former, who had not entered the premises, but had espied the outside of
the furnaces’ range at some distance, declared that “the coking process,
as performed at the ovens, is a species of distillation of coal”! How
rashly do unpractical theorists affirm what is utterly unfounded, and
mislead an unscientific judge! That the said coking process is in no
respect a species of distillation, but a complete combustion of the
volatile principles of the coal, will be manifest from the following
description of its actual progress. The mass of coals is first kindled
at the surface, as above stated, where it is supplied with abundance of
atmospheric oxygen; because the doors of the ovens in front, and the
throat-vents behind, are then left open. The consequence is, that no
more smoke is discharged from the top of the chimney, at this the most
sooty period of the process, than is produced by an ordinary kitchen
fire. In these circumstances, the coal gas, or other gas, supposed to be
generated in the slightly heated mass beneath, cannot escape destruction
in passing up through the bright open flame of the oven. As the coking
of the coal advances most slowly and regularly from the top of the heap
to the bottom, only one layer is affected at a time, and in succession
downwards, while the surface is always covered with a stratum of redhot
cinders, ready to consume every particle of carburetted or sulphuretted
hydrogen gases which may escape from below. The greatest mass, when
calcined in this downward order, cannot emit into the atmosphere any
more of the above-mentioned gases than the smallest heap; and therefore
the argument raised on account of the magnitude of the operations, is
altogether fallacious.

The coke being perfectly freed from all fuliginous and volatile matters
by a calcination of upwards of 40 hours, is cooled down to moderate
ignition by sliding in the dampers, and sliding up the doors, which had
been partially closed during the latter part of the process. It is now
observed to form prismatic concretions, somewhat like a columnar mass of
basalt. These are loosened by iron bars, lifted out upon shovels
furnished with long iron shanks, which are poised upon swing chains with
hooked ends, and the lumps are thrown upon the pavement, to be
extinguished by sprinkling water upon them from the rose of a
watering-can; or, they might be transferred into a large chest of
sheet-iron set on wheels, and then covered up. Good coals thus treated,
yield 80 per cent. of an excellent compact glistening coke; weighing
about 14 cwt. per chaldron.

The loss of weight in coking in the ordinary ovens is usually reckoned
at 25 per cent.; and coal, which thus loses one-fourth in weight, gains
one-fourth in bulk.

Labourers who have been long employed at rightly-constructed coke ovens,
seem to enjoy remarkably good health.


PITTACALL, is one of the 6 curious principles detected in wood-tar by
Reichenbach. It is a dark-blue solid substance, somewhat like indigo,
assumes a metallic fiery lustre on friction, and varies in tint from
copper to golden. It is void of taste and smell, not volatile;
carbonizes at a high heat without emitting an ammoniacal smell; is
soluble or rather very diffusible in water; gives a green solution with
a cast of crimson, in sulphuric acid, with a cast of red blue, in
muriatic acid, and with a cast of aurora red, in acetic acid. It is
insoluble in alkalis. It dyes a fast blue upon linen and cotton goods,
with tin and aluminous mordants.


PLASTER; see MORTAR.


PLASTER OF PARIS; see GYPSUM.


PLATED MANUFACTURE. (_Fabrique de plaqué_, Fr.; _Silber plattirung_,
Germ.) The silver in this case is not applied to ingots of pure copper,
but to an alloy consisting of copper and brass, which possesses the
requisite stiffness for the various articles.

The furnace used for melting that alloy, in blacklead crucibles, is a
common air-furnace, like that for making brass.

The ingot-moulds are made of cast iron, in two pieces, fastened
together; the cavity being of a rectangular shape, 3 inches broad, 1-1/2
thick, and 18 or 20 long. There is an elevated mouth-piece or gate, to
give pressure to the liquid metal, and secure solidity to the ingot. The
mould is heated, till the grease with which its cavity is besmeared,
merely begins to smoke, but does not burn. The proper heat of the melted
metal for casting, is when it assumes a bluish colour, and is quite
liquid. Whenever the metal has solidified in the mould, the wedges that
tighten its rings are driven out, lest the shrinkage of the ingot should
cause the mould to crack. See BRASS.

The ingot is now dressed carefully with the file on one or two faces,
according as it is to be single or double plated. The thickness of the
silver plate is such as to constitute one fortieth of the thickness of
the ingot; or when this is an inch and a quarter thick, the silver plate
applied is one thirty-second of an inch, being by weight a pound troy of
the former, to form 8 to 10 pennyweights of the latter. The silver,
which is slightly less in size than the copper, is tied to it truly with
iron wire, and a little of a saturated solution of borax is then
insinuated at the edges. This salt melts at a low heat, and excludes the
atmosphere, which might oxidize the copper, and obstruct the union of
the metals. The ingot thus prepared is brought to the plating furnace.

The furnace has an iron door with a small hole to look through; it is
fed with cokes, laid upon a grate at a level with the bottom of the
door. The ingot is placed immediately upon the cokes, the door is shut,
and the plater watches at the peep-hole the instant when the proper
soldering temperature is attained. During the union of the silver and
copper, the surface of the former is seen to be drawn into intimate
contact with the latter, and this species of _riveting_ is the signal
for removing the compound bar instantly from the furnace. Were it to
remain a very little longer, the silver would become alloyed with the
copper, and the plating be thus completely spoiled. The adhesion is, in
fact, accomplished here by the formation of a film of true silver-solder
at the surfaces of contact.

The ingot is next cleaned, and rolled to the proper thinness between
cylinders as described under MINT; being in its progress of lamination
frequently annealed on a small reverberatory hearth. After the last
annealing, the sheets are immersed in hot dilute sulphuric acid, and
scoured with fine Calais sand; they are then ready to be fashioned into
various articles.

In plating copper wire, the silver is first formed into a tubular shape,
with one edge projecting slightly over the other; through which a redhot
copper cylinder being somewhat loosely run, the silver edges are closely
pressed together with a steel burnisher, whereby they get firmly united.
The tube thus completed, is cleaned inside, and put on the proper copper
rod, which it exactly fits. The copper is left a little longer than its
coating tube, and is grooved at the extremities of the latter, so that
the silver edges, being worked into the copper groove, may exclude the
air from the surface of the rod. The compound cylinder is now heated
redhot, and rubbed briskly over with the steel burnisher in a
longitudinal direction, whereby the two metals get firmly united, and
form a solid rod, ready to be drawn into wire of any requisite fineness
and form; as flat, half-round, fluted, or with mouldings, according to
the figure of the hole in the draw-plate. Such wire is much used for
making bread-baskets, toast-racks, snuffers, and articles combining
elegance with lightness and economy. The wire must be annealed from time
to time during the drawing, and finally cleaned, like the plates, with
dilute acid.

Formerly the different shaped vessels of plated metal were all fashioned
by the hammer; but every one of simple form is now made in dies struck
with a drop-hammer or stamp. Some manufacturers employ 8 or 10 drop
machines.

[Illustration: 878 879 880 881]

_Fig._ 878. and 879. are two views of the stamp. A is a large stone, the
more massy the better; _b_, the anvil on which the die _e_ is secured by
four screws, as shown in the ground plan, _fig._ 880. In _fig._ 878., _a
a_ are two upright square prisms, set diagonally with the angles opposed
to each other; between which the hammer or drop _d_ slides truly, by
means of nicely fitted angular grooves or recesses in its sides. The
hammer is raised by pulling the rope _f_, which passes over the pulley
_c_, and is let fall from different heights, according to the impulse
required. Vessels which are less in diameter at the top and bottom than
in the middle, must either be raised by the stamp in two pieces, or
raised with a hand hammer. The die is usually made of _cast_ steel. When
it is placed upon the anvil, and the plated metal is cut into pieces of
proper size, the top of the die is then surrounded with a lute made of
oil and clay, for an inch or two above its surface; and the cavity is
filled with melted lead. The under face of the stamp-hammer has a plate
of iron called the _licker-up_ fitted into it, about the area of the
die. Whenever the lead has become solid, the hammer is raised to a
certain height, and dropped down upon it; and as the under face of the
licker-up is made rough like a rasp, it firmly adheres to the lead, so
as to lift it afterwards with the hammer. The plated metal is now placed
over the die, and the hammer mounted with its lead is let fall
repeatedly upon it, till the impression on the metal is complete. If the
vessel to be struck, be of any considerable depth, two or three dies may
be used, of progressive sizes in succession. But it occasionally happens
that when the vessel has a long conical neck, recourse must be had to an
auxiliary operation, called _punching_. See the embossing punches,
_fig._ 881. These are made of cast steel, with their hollows turned out
in the lathe. The pieces _a_, _b_ are of lead. The punching is performed
by a series of these tools, of different sizes, beginning with the
largest, and ending with the least. By this means a hollow cone, 3 or 4
inches deep, and an inch diameter, may be raised out of a flat plate.
These punches are struck with a hand hammer also, for small articles, of
too great delicacy for the drop. Indeed it frequently happens that one
part of an article is executed by the stamp, and another by the hand.

[Illustration: 882 883]

Cylindrical and conical vessels are mostly formed by bending and
soldering. The bending is performed on blocks of wood, with wooden
mallets; but the machine so much used by the tin-smiths, to form their
tubes and cylindric vessels (see the end section, _figs._ 882. and
883.), might be employed with advantage. This consists of 3 iron rollers
fixed in an iron frame. A, B, C, are the three cylinders, and _a_, _b_,
_c_, _d_, the riband or sheet of metal passed through them to receive
the cylindrical or conical curvature. The upper roller A can be raised
or lowered at pleasure, in order to modify the diameter of the tube; and
when one end of the roller is higher than the other, the conical
curvature is given. The edges of the plated cylinders or cones are
soldered with an alloy composed of silver and brass. An alloy of silver
and copper is somewhat more fusible; but that of brass and silver
answers best for plated metal, the brass being in very small proportion,
lest the colour of the plate be affected. Calcined borax mixed with
sandiver (the salt skimmed from the pots of crown glass) is used along
with the alloy, in the act of soldering. The seam of the plated metal
being smeared with that saline mixture made into a pap with water, and
the bits of laminated solder, cut small with scissors, laid on, the seam
is exposed to the flame of an oil blowpipe, or to that of charcoal urged
by bellows in a little forge-hearth, till the solder melts and flows
evenly along the junction. The use of the sandiver seems to be, to
prevent the iron wire that binds the plated metal tube from being
soldered to it.

[Illustration: 884 885 886 887 888]

Mouldings are sometimes formed upon the edges of vessels, which are not
merely ornamental, but give strength and stiffness. These are fashioned
by an instrument called a _swage_, represented in _figs._ 884. and 885.
The part A lifts up by a joint, and the metal to be _swaged_ is placed
between the dies, as shown in the figures; the tail _b_ being held in
the jaws of a vice, while the shear-shaped hammer rests upon it. By
striking on the head A, while the metal plate is shifted successively
forwards, the beading is formed. In _fig._ 884. the tooth _a_ is a guide
to regulate the distance between the bead and the edge. A similar effect
is produced of late years in a neater and more expeditious manner by the
rollers, _figs._ 886. 887. _Fig._ 888. is a section to show the form of
the bead. The two wheels _a_, _a_, _fig._ 886., are placed upon axes,
two of which are furnished with toothed pinions in their middle; the
lower one being turned by the handle, gives motion to the upper. The
groove in the upper wheel corresponds with the bead in the lower, so
that the slip of metal passed through between them assumes the same
figure.

The greatest improvement made in this branch of manufacture, is the
introduction of silver edges, beads and mouldings, instead of the plated
ones, which from their prominence had their silver surface speedily worn
off, and thus assumed a brassy look. The silver destined to form the
ornamental edgings is laminated exceedingly thin; a square inch
sometimes weighing no more than 10 or 12 grains. This is too fragile to
bear the action of the opposite steel dies of the swage above described.
It is necessary, therefore, that the sunk part of the die should be
steel, and the opposite side lead, as was observed in the stamping; and
this is the method now generally employed to form these silver
ornaments. The inside shell of this silver moulding is filled with soft
solder, and then bent into the requisite form.

The base of candlesticks is generally made in a die by the stamp, as
well as the neck, the dish part of the nozzle or socket, and the tubular
stem or pillar. The different parts are united, some with soft and
others with hard solder. The branches of candlesticks are formed in two
semi-cylindrical halves, like the feet of tea-urns. When an article is
to be engraved on, an extra plate of silver is applied at the proper
part, while the plate is still flat, and fixed by burnishing with great
pressure over a hot anvil. This is a species of welding.

The last finish of plated goods is given by burnishing-tools of
bloodstone, fixed in sheet-iron cases, or hardened steel, finely
polished.

The ingots for lamination might probably be plated with advantage by the
delicate pressure process employed for silvering copper wire.

The total value of the plate, plated ware, jewellery, and watches,
exported in the year 1836, was 338,889_l._; but the value of the plated
goods is not given in the tables of revenue. M. Parquin, the greatest
manufacturer of plated goods in Paris (or France, for this business is
monopolized by the capital), who makes to the value of 700,000 francs
per annum, out of the 1,500,000 which, he says, is the whole internal
consumption of the kingdom, states that the internal consumption of the
United Kingdom amounts 30,000,000, or 20 times, that of France! He adds,
that our common laminated copper costs 26 sous the pound, while theirs
costs 34. Their plated goods are fashioned, not in general with stamps,
but by the pressure of tools upon wood moulds in the turning-lathe,
which is a great economy of capital to the manufacturer. There are
factories at Birmingham which possess a heavy stock of 300,000 different
die-moulds. See STAMPING OF METALS.


PLATINA-MOHR. The following easy method of preparing igniferous black
platinum, proposed thirty years ago by Descotils, has been recently
recommended by M. Dobereiner:--

Melt platina ore with double its weight of zinc, reduce the alloy to
powder, and treat it first with dilute sulphuric acid, and next with
dilute nitric acid, to oxidize and dissolve out all the zinc, which,
contrary to one’s expectations, is somewhat difficult to do, even at a
boiling heat. The insoluble black-gray powder contains some osmiuret of
iridium, united with the crude platinum. This compound acts like simple
platina-black, after it has been purified by digestion in potash lye,
and washing with water. Its oxidizing power is so great, as to transform
not only the formic acid into the carbonic, and alcohol into vinegar,
but even some osmic acid, from the metallic osmium. The above powder
explodes by heat like gunpowder.

When the platina-_mohr_ prepared by means of zinc is moistened with
alcohol, it becomes incandescent, and emits osmic acid; but if it be
mixed with alcohol into a paste, and spread upon a watch-glass, nothing
but acetic acid will be disengaged; affording an elegant means of
diffusing the odour of vinegar in an apartment.


PLATINUM, is a metal of a grayish-white colour, resembling in a good
measure polished steel. It is harder than silver, and of about double
its density, being of specific gravity 21. It is so infusible, that no
considerable portion of it can be melted by the strongest heats of our
furnaces. It is unchangeable in the air and water; nor does a white heat
impair its polish. The only acid which dissolves it, is the
nitro-muriatic; the muriate or chloride thus formed, affords, with pure
ammonia or sal ammoniac, a triple salt in a yellow powder, convertible
into the pure metal by a red heat. This character distinguishes platinum
from every other metal.

_Native Platinum._--In the natural state it is never pure, being alloyed
with several other metals. It occurs only under the form of grains,
which are usually flattened, and resemble in shape the gold _pepitas_.
Their size is in general less than linseed, although in some cases they
equal hempseed, and, occasionally, peas. One piece brought from Choco,
in Peru, and presented to the Cabinet of Berlin, by M. Humboldt, weighs
55 grammes = 850 grains, or nearly 2 oz. avoirdupois. The greatest lump
of native platinum known, till of late years, was one in the Royal
Museum of Madrid, which was found in 1814 in the gold mine of Condoto,
province of Novita, at Choco. Its size is greater than a Turkey’s egg,
(about 2 inches one diameter, and 4 inches the other,) and its weight
760 grammes, = 24 oz. or fully 2 lbs. troy. See _infrà_.

The colour of the grains of native platinum is generally a grayish
white, like tarnished steel. The cavities of the rough grains are often
filled with earthy and ferruginous matters, or sometimes with small
grains of black oxide of iron, adhering to the surface of the platinum
grains. Their specific gravity is also much lower than that of forged
pure platinum; varying from 15 in the small particles, to 18·94 in M.
Humboldt’s large specimen. This relative lightness is owing to the
presence of iron, copper, lead, and chrome; besides its other more
lately discovered metallic constituents, palladium, osmium, rhodium, and
iridium.

Its main localities in the New Continent, are in the three following
districts:--

1. At Choco, in the neighbourhood of Barbacoas, and generally on the
coasts of the South Sea, or on the western slopes of the Cordillera of
the Andes, between the 2nd and the 6th degrees of north latitude. The
gold-washings that furnish most platinum, are those of Condoto, in the
province of Novita; those of Santa Rita, or Viroviro, of Santa Lucia, of
the ravine of Iro, and Apoto, between Novita and Taddo. The deposit of
gold and platinum grains is found in alluvial ground, at a depth of
about 20 feet. The gold is separated from the platinum by picking with
the hand, and also by amalgamation; formerly, when it was imagined that
platinum might be used to debase gold, the grains of the former metal
were thrown into the rivers, through which mistaken opinion an immense
quantity of it was lost.

2. Platinum grains are found in Brazil, but always in the alluvial lands
that contain gold, particularly in those of Matto-Grosso. The ore of
this country is somewhat different from that of Choco. It is in grains,
which seem to be fragments of a spongy substance. The whole of the
particles are nearly globular, exhibiting a surface formed of small
spheroidal protuberances strongly cohering together, whose interstices
are clean, and even brilliant.

This platinum includes many small particles of gold, but none of the
magnetic iron-sand or of the small zircons which accompany the Peruvian
ore. It is mixed with small grains of native palladium, which may be
recognised by their fibrous or radiated structure, and particularly by
their chemical characters.

3. Platinum grains are found in Hayti, or Saint Domingo, in the sand of
the river Jacky, near the mountains of Sibao. Like those of Choco, they
are in small brilliant grains, as if polished by friction. The sand
containing them is quartzose and ferruginous. This native platinum
contains, like that of Choco, chromium, copper, osmium, iridium,
rhodium, palladium, and probably titanium. Vauquelin could find no gold
among the grains.

Platinum has been discovered lately in the Russian territories, in the
auriferous sands of Kuschwa, 250 wersts from Ekaterinebourg, and
consequently in a geological position which seems to be analogous with
that of South America.

These auriferous sands are, indeed, almost all superficial; they cover
an argillaceous soil; and include, along with gold and platinum, debris
of dolerite (a kind of greenstone), protoxide of iron, grains of
corundum, &c. The platinum grains are not so flat as those from Choco,
but they are thicker; they have less brilliancy, and more of a leaden
hue. This platinum, by M. Laugier’s analysis, is similar in purity to
that of Choco; but the leaden-gray grains, which were taken for a
mixture of osmium and iridium, are merely an alloy of platinum,
containing 25 per cent. of these metals.

The mines of Brazil, Columbia, and Saint Domingo furnish altogether only
about 400 kilos. of platinum ore per annum; but those of Russia produce
above 1800 kilos. The latter were discovered in 1822, and were first
worked in 1824. They are all situated in the Ural mountains. The ore is
disseminated in an argillaceous sand, of a greenish-gray colour,
resulting from the disintegration of the surrounding rocks, and
constitutes from 1 to 3 parts in 4000 of the sand. Occasionally it has
been found in lumps weighing 8 kilogrammes (16 lbs.!), but it generally
occurs in blackish angular grains, which contain 70 per cent. of
platinum, and 3 to 5 of iridium. The ore of Goroblagodat is in small
flattened grains, which contain 88 per cent. of this precious metal. The
osmiure of iridium is found upon a great many points of the Urals,
throughout a space of 140 leagues, being a product accessory to the gold
washings. 32 kilogrammes of osmiure are collected there annually, which
contain upon an average 2 per cent. of platinum.

M. Vauquelin found nearly ten per cent. of platinum in an ore of
argentiferous copper, which was transmitted to him as coming from
Guadalcanal in Spain. This would be the only example of platinum
existing in a rock, and in a vein. As the same thing has not again been
met with, even in other specimens from Guadalcanal, we must delay
drawing geological inferences, till a new example has confirmed the
authenticity of the first.

Platinum has been known in Europe only since 1748, though it was noticed
by Ulloa in 1741. It was compared at first to gold; and was, in fact,
brought into the market under the name of white gold. The term platinum,
however, is derived from the Spanish word _plata_, silver, on account of
its resemblance in colour to that metal.

The whole of the platinum ore from the Urals is sent to St. Petersburg,
where it is treated by the following simple process:--

One part of the ore is put in open platina vessels, capable of
containing from 6 to 8 lbs., along with 3 parts of muriatic acid at 25°
B. and 1 part of nitric acid at 40°. Thirty of these vessels are placed
upon a sand-bath covered with a glazed dome with movable panes, which is
surmounted by a ventilating chimney to carry the vapours out of the
laboratory. Heat is applied for 8 or 10 hours, till no more red vapours
appear; a proof that the whole nitric acid is decomposed, though some of
the muriatic remains. After settling, the supernatant liquid is decanted
off into large cylindrical glass vessels, the residuum is washed, and
the washing is also decanted off. A fresh quantity of nitro-muriatic
acid is now poured upon the residuum. This treatment is repeated till
the whole solid matter has eventually disappeared. The ore requires for
solution from 10 to 15 times its weight of nitro-muriatic acid,
according to the size of its grains.

The solutions thus made are all acid; a circumstance essential to
prevent the iridium from precipitating with the platinum, by the water
of ammonia, which is next added. The deposit being allowed to form, the
mother waters are poured off, the precipitate is washed with cold water,
dried, and calcined in crucibles of platinum.

The mother-waters and the washings are afterwards treated separately.
The first being concentrated to one-twelfth of their bulk in glass
retorts, on cooling they let fall the iridium in the state of an
ammoniacal chloride, constituting a dark-purple powder, occasionally
crystallized in regular octahedrons. The washings are evaporated to
dryness in porcelain vessels; the residuum is calcined and treated like
fresh ore; but the platinum it affords needs a second purification.

For agglomerating the platinum, the spongy mass is pounded in bronze
mortars; the powder is passed through a fine sieve, and put into a
cylinder of the intended size of the ingot. The cylinder is fitted with
a rammer, which is forced in by a coining press, till the powder be much
condensed. It is then turned out of the mould, and baked 36 hours in a
porcelain kiln, after which it may be readily forged, if it be pure, and
may receive any desired form from the hammer. It contracts in volume
from 1-6th to 1-5th during the calcination. The cost of the manufacture
of platinum is fixed by the administration at 32 francs the Russian
pound; but so great a sum is never expended upon it.

For Dr. Wollaston’s process, see Phil. Trans. 1829, Part I.

Platinum furnishes most valuable vessels to both analytical and
manufacturing chemists. It may be beat out into leaves of such thinness
as to be blown about with the breath.

This metal is applied to porcelain by two different processes; sometimes
in a rather coarse powder, applied by the brush, like gold, to form
ornamental figures; sometimes in a state of extreme division, obtained
by decomposing its muriatic solution, by means of an essential oil, such
as rosemary or lavender. In this case, it must be evenly spread over the
whole ground. Both modes of application give rise to a steely lustre.

The properties possessed in common by gold and platinum, have several
times given occasion to fraudulent admixtures, which have deceived the
assayers. M. Vauquelin having executed a series of experiments to
elucidate this subject, drew the following conclusions:--

If the platinum do not exceed 30 or 40 parts in the thousand of the
alloy, the gold does not retain any of it when the parting is made with
nitric acid in the usual way; and when the proportion of platinum is
greater, the fraud becomes manifest, 1st by the higher temperature
required to pass it through the cupel, and to form a round button, 2, by
the absence of the lightning, fulguration, or coruscation; 3, by the
dull white colour of the button and its crystallized surface; 4, by the
straw-yellow colour which platinum communicates to the aquafortis in the
parting; 5, by the straw-yellow colour, bordering on white, of the
cornet, after it is annealed. If the platinum amounts to one fourth of
the gold, we must add to the alloy at least 3 times its weight of fine
silver, laminate it very thin, anneal somewhat strongly, boil it half an
hour in the first aquafortis, and at least a quarter of an hour in the
second, in order that the acid may dissolve the whole of the platinum.

Were it required to determine exactly the proportions of platinum
contained in an alloy of copper, silver, gold, and platinum, the amount
of the copper may be found in the first place by _cupellation_, then the
respective quantities of the three other metals may be learned by a
process founded, 1, upon the property possessed by sulphuric acid of
dissolving silver without affecting gold or platinum; and, 2, upon the
property of platinum being soluble in the nitric acid, when it is
alloyed with a certain quantity of gold and silver.

According to Boussingault, the annual product of Platinum in America
does not exceed 8-1/3 cwts. At Nischne-Tagilsk, in 1824, a lump of
native platinum weighing fully 10 lbs. was found; and in 1830, another
lump, of nearly double size, which weighed 35-3/4 Prussian marcs; fully
18 lbs. avoirdupoise.

PRODUCTION OF PLATINUM IN THE URAL.

  From 1822 to 1827 inclusively, 52 puds[41] and 22-1/2 pounds.
               1828              94
               1829              78              31-1/2
               1830             105               1
               1831 to 1833     348              15


  [41] One pud = 40 Russian pounds, = 69,956 Prussian marcs (see
  SILVER); 1 pound = 96 zolotniki.

ANALYSES of the PLATINUM ORES of the Urals, and of that from Barbacoas
on the Pacific, between the 2nd and 6th degrees of northern latitude.

  +------------+---------------------+-------------+----------+
  |            |From Nischne-Tagilsk.|             |          |
  |            |    Berzelius.       |Goroblagodat.|Barbacoas.|
  |            |          |   Not    |   Osann.    |Berzelius.|
  |            | Magnetic.| Magnetic |             |          |
  +------------+----------+----------+-------------+----------+
  |Platinum    |   73·58  |   78·94  |83·07 | 86·50|  84·30   |
  |Iridium     |    2·35  |    4·97  | 1·91 |      |   1·46   |
  |Rhodium     |    1·15  |    0·86  | 0·59 |  1·15|   3·46   |
  |Palladium   |    0·30  |    0·28  | 0·26 |  1·10|   1·06   |
  |Iron        |   12·98  |   11·04  |10·79 |  8·32|   5·31   |
  |Copper      |    5·20  |    0·70  | 1·30 |  0·45|   0·74   |
  |Undissolved}|          |          |      |      |          |
  |Osmium and }|    2·30  |    1·96  | 1·80 |  1·40|          |
  |Iridium    }|          |          |      |      |          |
  |Osmium      |          |          |      |      |   1·03   |
  |Quartz      |          |          |      |      |   0·60   |
  |Lime        |          |          |      |      |   0·12   |
  |            +----------+----------+------+------+----------+
  |            |   97·86  |   98·75  |99·72 | 98·92|  98·08   |
  +------------+----------+----------+------+------+----------+


PLUMBAGO. See GRAPHITE, for its mineralogical and chemical characters.
The mountain at Borrowdale, in which the blacklead is mined, is 2000
feet high, and the entrance to the mine is 1000 feet below its summit.
This valuable mineral became so common a subject of robbery about a
century ago, as to have enriched, it was said, a great many persons
living in the neighbourhood. Even the guard stationed over it by the
proprietors was of little avail against men infuriated with the love of
plunder; since in those days a body of miners broke into the mine by
main force, and held possession of it for a considerable time.

The treasure is now protected by a strong building, consisting of four
rooms upon the ground floor; and immediately under one of them is the
opening, secured by a trap-door, through which alone workmen can enter
the interior of the mountain. In this apartment, called the
dressing-room, the miners change their ordinary clothes for their
working dress, as they come in, and after their six hours’ post or
journey, they again change their dress, under the superintendence of the
steward, before they are suffered to go out. In the innermost of the
four rooms, two men are seated at a large table, sorting and dressing
the plumbago, who are locked in while at work, and watched by the
steward from an adjoining room, who is armed with two loaded
blunderbusses. Such formidable apparatus of security is deemed requisite
to check the pilfering spirit of the Cumberland mountaineers.

The cleansed blacklead is packed up into strong casks, which hold 1 cwt.
each. These are all despatched to the warehouse of the proprietors in
London, where the blacklead is sold monthly by auction, at a price of
from 35_s._ to 45_s._ a pound.

In some years, the net produce of the _six weeks’_ annual working of the
mine has, it is said, amounted to 30,000_l._ or 40,000_l._


PLUSH (_Panne_, _Peluche_, Fr.; _Wollsammet_, _Plüsch_, Germ.), is a
textile fabric, having a sort of velvet nap or shag upon one side. It is
composed regularly of a woof of a single woollen thread, and a two-fold
warp, the one, wool of two threads twisted, the other, goat’s or camel’s
hair. There are also several sorts of plush made entirely of worsted. It
is manufactured, like velvet, in a loom with three treadles; two of
which separate and depress the woollen warp, and the third raises the
hair-warp, whereupon the weaver, throwing the shuttle, passes the woof
between the woollen and hair warp; afterwards, laying a brass broach or
needle under that of the hair, he cuts it with a knife (see FUSTIAN)
destined for that use, running its fine slender point along in the
hollow of the guide-broach, to the end of a piece extended upon a table.
Thus the surface of the plush receives its velvety appearance. This
stuff is also made of cotton and silk.


POINT NET, is a style of lace formerly much in vogue, but now superseded
by the bobbin-net manufacture.


PORCELAIN, is the finest kind of pottery-ware. It is considered under
that title.


PORPHYRY, is a compound mineral or rock, composed essentially of a base
of hornstone, interspersed with crystals of felspar. It frequently
contains also quartz, mica, and hornblende. That most esteemed is the
antient porphyry of Egypt, with a ground of a fine red colour passing
into purple, having snow-white crystals of felspar imbedded in it. Most
beautiful specimens of it are to be seen in the antique colossal statues
in the British Museum.

Porphyry occurs in Arran, and in Perthshire between Dalnacardoch and
Tummel bridge. It is much used for making slabs, mullers, and mortars.


PORTER, is a malt liquor, so called from being the favourite beverage of
the porters and workpeople of the metropolis and other large towns of
the British empire; it is characterized by its dark-brown colour, its
transparency, its moderately bitter taste, and peculiar aromatic
flavour, which, along with its tonic and intoxicating qualities, make it
be keenly relished by thirsty palates accustomed to its use. At first
the essential distinction of porter arose from its wort being made with
highly-kilned brown malt, while other kinds of beer and ale were brewed
from a paler article; but of late years, the taste of the public having
run in favour of sweeter and lighter beverages, the actual porter is
brewed with a less proportion of brown malt, is less strongly hopped,
and not allowed to get hard by long keeping in huge ripening tuns. Some
brewers colour the porter with burnt sugar; but in general the most
respectable concentrate a quantity of their first and best wort to an
extract, in an iron pan, and burn this into a _colouring_ stuff, whereby
they can lay claim to the merit of using nothing in their manufacture
but malt and hops. The singular flavour of good London porter seems to
proceed, in a great degree, from that of the old casks and fermenting
tuns in which it is prepared. Though not much addicted to vinous
potations of any kind, I feel warranted by long experience to opine,
that the porter brewed by the eminent London houses, when drunk in
moderation, is a far wholesomer beverage for the people than the thin
acidulous wines of France and Germany. See BEER.


PORTLAND STONE, is a fine compact oolite, so named from the island where
it is quarried. It is a convenient but not a durable building-stone.


POTATO (_Pomme de terre_, Fr.; _Kartoffel_, Germ.); is the well-known
root of the _Solanum tuberosum_.

The following TABLE exhibits several good analyses of the potato:--

  +-------------------+------+-------+----+-----+------+------+-------+
  |      Sort.        |  Fi- |Starch.|Veg.|Gum. |Acids |Water.|  Ana- |
  |                   |brine.|       |al- |     | and  |      | lyst. |
  |                   |      |       |bum.|     |Salts.|      |       |
  +-------------------+------+-------+----+-----+------+------+-------+
  |Red potatos        | 7·0  | 15·0  |1·4 | 4·1 | 5·1  |75·0  |Einhof.|
  |Id. germinated     | 6·8  | 15·2  |1·3 | 3·7 |      |73·0  |       |
  |Potato sprouts     | 2·8  |  0·4  |0·4 | 3·3 |      |93·0  |       |
  |Kidney potatos     | 8·8  |  9·1  |0·8 |     |      |81·3  |       |
  |Large red do.      | 6·0  | 12·9  |0·7 |     |      |78·0  |       |
  |Sweet do.          | 8·2  | 15·1  |0·8 |     |      |74·3  |       |
  |                   |      |       |    | \_______/  |      |       |
  |Potato of Peru     | 5·2  | 15·0  |1·9 |    1·9     |76·0  |Lampad.|
  |   . .    England  | 6·8  | 12·9  |1·1 |    1·7     |77·5  |       |
  |Onion potato       | 8·4  | 18·7  |0·9 |    1·7     |70·3  |       |
  | . .  Voigtland    | 7·1  | 15·4  |1·2 |    2·0     |74·3  |       |
  | . .  cultivated in|      |       |    |     |      |      |       |
  |the environs of    |      |       |    |     |      |      |       |
  |Paris              | 6·79 | 13·3  |0·92| 3·3 | 1·4  |73·12 |Henry. |
  +-------------------+------+-------+----+-----+------+------+-------+


POTASH, or POTASSA. (_Potasse_, Fr.; _Kali_, Germ.) This substance was
so named from being prepared for commercial purposes by evaporating in
iron pots the lixivium of the ashes of wood fuel. In the crude state
called potashes, it consists, therefore, of such constituents of burned
vegetables as are very soluble in water, and fixed in the fire. The
potash salts of plants which originally contained vegetable acids, will
be converted into carbonates, the sulphates will become sulphites,
sulphurets, or even carbonates, according to the manner of incineration;
the nitrates will be changed into pure carbonates, while the muriates or
chlorides will remain unaltered. Should quicklime be added to the
solution of the ashes, a corresponding portion of caustic potassa will
be introduced into the product, with more or less lime, according to the
care taken in decanting off the clear lye for evaporation.

In America, where timber is in many places an incumbrance upon the soil,
it is felled, piled up in pyramids, and burned, solely with a view to
the manufacture of potashes. The ashes are put into wooden cisterns,
having a plug at the bottom of one of the sides under a false bottom; a
moderate quantity of water is then poured on the mass, and some
quicklime is stirred in. After standing for a few hours, so as to take
up the soluble matter, the clear liquor is drawn off; evaporated to
dryness in iron pots, and finally fused at a red heat into compact
masses, which are gray on the outside, and pink-coloured within.

Pearlash is prepared by calcining potashes upon a reverberatory hearth,
till the whole carbonaceous matter, and the greater part of the sulphur,
be dissipated; then lixiviating the mass, in a cistern having a false
bottom covered with straw, evaporating the clear lye to dryness in flat
iron pans, and stirring it towards the end into white lumpy
granulations.

I find the best pink Canadian potashes, as imported in casks containing
about 5 cwts., to contain pretty uniformly 60 per cent. of absolute
potassa; and the best pearlashes to contain 50 per cent.; the alkali in
the former being nearly in a caustic state; in the latter, carbonated.

All kinds of vegetables do not yield the same proportion of potassa. The
more succulent the plant, the more does it afford; for it is only in the
juices that the vegetable salts reside, which are converted by
incineration into alkaline matter. Herbaceous weeds are more productive
of potash than the graminiferous species, or shrubs, and these than
trees; and for a like reason, twigs and leaves are more productive than
timber. But plants in all cases are richest in alkaline salts when they
have arrived at maturity. The soil in which they grow also influences
the quantity of saline matter.

The following TABLE exhibits the average product in potassa of several
plants, according to the researches of Vauquelin, Pertuis, Kirwan, and
De Saussure:--

  In 1000 parts.                            Potassa.

  Pine or fir                                  0·45
  Poplar                                       0·75
  Trefoil                                      0·75
  Beechwood                                    1·45
  Oak                                          1·53
  Boxwood                                      2·26
  Willow                                       2·85
  Elm and maple                                3·90
  Wheat straw                                  3·90
  Barb of oak twigs                            4·20
  Thistles                                     5·00
  Flax stems                                   5·00
  Small rushes                                 5·08
  Vine shoots                                  5·50
  Barley straw                                 5·80
  Dry beech bark                               6·00
  Fern                                         6·26
  Large rush                                   7·22
  Stalk of maize                              17·5
  Bastard chamomile (_Anthemis cotula_, L.)   19·6
  Bean stalks                                 20·0
  Sunflower stalks                            20·0
  Common nettle                               25·03
  Vetch plant                                 27·50
  Thistles in full growth                     35·37
  Dry straw of wheat before earing            47·0
  Wormwood                                    73·0
  Fumitory                                    79·0

Stalks of tobacco, potatos, chesnuts, chesnut husks, broom, heath,
furze, tansy, sorrel, vine leaves, beet leaves, orach, and many other
plants, abound in potash salts. In Burgundy, the well-known _cendres
gravelées_ are made by incinerating the lees of wine pressed into cakes,
and dried in the sun; the ashes contain fully 16 per cent. of potassa.

The purification of pearlash is founded upon the fact of its being more
soluble in water than the neutral salts which debase it. Upon any given
quantity of that substance, in an iron pot, let one and a half times its
weight of water be poured, and let a gentle heat be applied for a short
time. When the whole has again cooled, the bottom will be encrusted with
the salts, while a solution of nearly pure carbonate of potash will be
found floating above, which may be drawn off clear by a syphon. The
salts may be afterwards thrown upon a filter of gravel. If this lye be
diluted with 6 times its bulk of water mixed with as much slaked lime as
there was pearlash employed, and the mixture be boiled for an hour, the
potash will become caustic, by giving up its carbonic acid to the lime.
If the clear settled lixivium be now siphoned off, and concentrated by
boiling in a covered iron pan, till it assumes the appearance of oil, it
will constitute the common caustic of the surgeon, the _potassa fusa_ of
the shops. But to obtain potassa chemically pure, recourse must be had
to the bicarbonate, nitrate, or tartrate of potassa, salts which, when
carefully crystallized, are exempt from any thing to render the potassa
derived from them impure. The bicarbonate having been gently ignited in
a silver basin, is to be dissolved in 6 times its weight of water, and
the solution is to be boiled for an hour, along with one pound of slaked
lime for every pound of the bicarbonate used. The whole must be left to
settle without contact of air. The supernatant lye is to be drawn off by
a syphon, and evaporated in an iron or silver vessel provided with a
small orifice in its close cover for the escape of the steam, till it
assumes, as above, the appearance of oil, or till it be nearly redhot.
Let the fused potassa be now poured out upon a bright plate of iron, cut
into pieces as soon as it concretes, and put up immediately in a bottle
furnished with a well-ground stopper. It is hydrate of potassa, being
composed of 1 atom of potassa 48, + 1 atom of water 9, = 57.

A pure carbonate of potassa may be also prepared by fusing pure nitre in
an earthen crucible, and projecting charcoal into it by small bits at a
time, till it ceases to cause deflagration. Or a mixture of 10 parts of
nitre and 1 of charcoal may be deflagrated in small successive portions
in a redhot deep crucible. When a mixture of 2 parts of tartrate of
potassa, or crystals of tartar, and 1 of nitre, is deflagrated, pure
carbonate of potassa remains mixed with charcoal, which by lixiviation,
and the agency of quicklime, will afford a pure hydrate. Crystals of
tartar calcined alone yield also a pure carbonate.

Caustic potassa, as I have said, after being fused in a silver crucible
at a red heat, retains 1 prime equivalent of water. Hence its
composition in 100 parts is, potassium 70, oxygen 14, water 16.
Anhydrous potassa, or the oxide free from water, can be obtained only by
the combustion of potassium in the open air. It is composed of 83-1/3 of
metal, and 16-2/3 of oxygen. Berzelius’s numbers are 83·05 and 16·95.

Caustic potassa may be crystallized; but in general it occurs as a white
brittle substance of spec. grav. 1·708, which melts at a red heat,
evaporates at a white heat, deliquesces into a liquid in the air, and
attracts carbonic acid; is soluble in water and alcohol, forms soft
soaps with fat oils, and soapy-looking compounds with resins and wax;
dissolves sulphur, some metallic sulphurets, as those of antimony,
arsenic, &c., as also silica, alumina, and certain other bases; and
decomposes animal textures, as hair, wool, silk, horn, skin, &c. It
should never be touched with the tongue or the fingers.

The following TABLE exhibits the quantity of _Fused Potassa_ in 100
parts of _caustic lye_, at the respective densities:--

  +----+-------+
  |Sp. | Pot.  |
  |gr. |in 100.|
  +----+-------+
  |1·58| 53·06 |
  |1·56| 51·58 |
  |1·54| 50·09 |
  |1·52| 48·46 |
  |1·50| 46·45 |
  |1·48| 44·40 |
  |1·46| 42·31 |
  |1·44| 40·17 |
  |1·42| 37·97 |
  |1·40| 35·99 |
  |1·38| 34·74 |
  |1·36| 33·46 |
  |1·34| 32·14 |
  |1·32| 30·74 |
  |1·30| 29·34 |
  |1·28| 27·86 |
  |1·26| 26·34 |
  |1·24| 24·77 |
  |1·22| 23·14 |
  |1·20| 21·25 |
  |1·18| 19·34 |
  |1·16| 17·40 |
  |1·14| 15·38 |
  |1·12| 13·30 |
  |1·10| 11·28 |
  |1·08|  9·20 |
  |1·06|  7·02 |
  |1·04|  4·77 |
  |1·02|  2·44 |
  |1·00|  0·00 |
  +----+-------+

The only certain way of determining the quantity of free potassa in any
solid or liquid, is from the quantity of a dilute acid of known strength
which it can saturate.

The hydrate of potassa, or its lye, often contains a notable quantity of
carbonate, the presence of which may be detected by lime water, and its
amount be ascertained by the loss of weight which it suffers, when a
weighed portion of the lye is poured into a weighed portion of dilute
sulphuric acid poised in the scale of a balance.

There are two other oxides of potassium; the suboxide, which consists,
according to Berzelius, of 90·74 of metal, and 9·26 oxygen; and the
hyperoxide, an orange-yellow substance, which gives off oxygen in the
act of dissolving in water, and becomes potassa. It consists of 62 of
metal, and 38 of oxygen.

Carbonate of potassa is composed of 48 parts of base, and 22 of acid,
according to most British authorities; or, in 100 parts, of 68·57 and
31·43; but according to Berzelius, of 68·09 and 31·91.

Carbonate of potassa, as it exists associated with carbon in calcined
tartar, passes very readily into the _Bicarbonate_, on being moistened
with water, and having a current of carbonic acid gas passed through it.
The absorption takes place so rapidly, that the mass becomes hot, and
therefore ought to be surrounded with cold water. The salt should then
be dissolved in the smallest quantity of water at 120° F., filtered, and
crystallized.


POTASSIUM (Eng. and Fr.; _Kalium_, Germ.); is a metal deeply
interesting, not only from its own marvellous properties, but from its
having been the first link in the chain of discovery which conducted Sir
H. Davy through many of the formerly mysterious and untrodden labyrinths
of chemistry.

The easiest and best mode of obtaining this elementary substance, is
that contrived by Brunner, which I have often practised upon a
considerable scale. Into the orifice of one of the iron bottles, as A,
_fig._ 889., in which mercury is imported, adapt, by screwing, a piece
of gun-barrel tube, 9 inches long; having brazed into its side, about 3
inches from its outer end, a similar piece of iron tube. Fill this
retort two-thirds with a mixture of 10 parts of cream of tartar,
previously calcined in a covered crucible, and 1 of charcoal, both in
powder; and lay it horizontally in an air-furnace, so that while the
screw orifice is at the inside wall, the extremity of the straight or
nozzle tube may project a few inches beyond the brickwork, and the tube
brazed into it at right angles may descend pretty close to the outside
wall, so as to dip its lower end a quarter of an inch beneath the
surface of some rectified naphtha contained in a copper bottle
surrounded by ice-cold water. By bringing the condenser-vessel so near
the furnace, the tubes along which the potassium vapour requires to
pass, run less risk of getting obstructed. The horizontal straight end
of the nozzle tube should be shut by screwing a stopcock air-tight into
it. By opening the cock momentarily, and thrusting in a hot wire, this
tube may be readily kept free, without permitting any considerable waste
of potassium. The heat should be slowly applied at first, but eventually
urged to whiteness, and continued as long as potassuretted hydrogen
continues to be disengaged. The retort, and the part of the nozzle tube
exposed to the fire, should be covered with a good refractory lute, as
described under the article PHOSPHORUS. The joints must be perfectly
air-tight; and the vessel freed from every trace of mercury, by
ignition, before it is charged with the tartar-ash.

Tartar skilfully treated in this way will afford 3 per cent. of
potassium; and when it is observed to send forth green fumes, it has
commenced the production of the metal. Instead of the construction above
described, the following form of apparatus may be employed.

[Illustration: 889 890]

A. _fig._ 889., represents the iron bottle, charged with the incinerated
tartar; and B is a fire-brick support. A piece of fire-tile should also
be placed between the bottom of the bottle and the back wall of the
furnace, to keep the apparatus steady during the operation. Whenever the
moisture is expelled, and the mass faintly ignited, the tube C should be
screwed into the mouth of the bottle, through a small hole left for this
purpose in the side of the furnace. That tube should be no longer, and
the front wall of the furnace no thicker, than what is absolutely
necessary. As soon as the reduction is indicated by the emission of
green vapours, the receiver must be adapted, _d_, _a_, D, E, shown in a
large scale in _fig._ 890.

This is a condenser, in two pieces, made of thin sheet copper; D, the
upper part, is a rectangular box, open at bottom, about 10 inches high,
by 5 or 6 long, and 2 wide; near to the side _a_, it is divided inside
into two equal compartments, up to two-thirds of its height, by a
partition _b_, _b_, in order to make the vapours that issue from C
pursue a downward and circuitous path. In each of its narrow sides, near
the top, a short tube is soldered, at _d_ and _a_; the former being
fitted air-tight into the end of the nozzle of the retort, while the
latter is closed with a cork traversed by a stiff iron probe _e_, which
passes through a small hole in the partition _b_, _b_, under _c_, and is
employed to keep the tube C clear, by its drill-shaped steel point. In
one of the broad sides of the box D, near the top, a bit of pipe is
soldered on at _e_, for receiving the end of a bent glass tube of
safety, which dips its other and lower end into a glass containing
naphtha. E, the bottom copper box, with naphtha, which receives pretty
closely the upper case D, is to be immersed in a cistern of cold water
containing some lumps of ice.

The chemical action by which potassa is reduced in this process, seems
to be somewhat complicated, and has not been thoroughly explained. A
very small proportion of pure potassium is obtained; a great deal of it
is converted into a black infusible mass, which passes over with the
metal, and is very apt to block up the tube. Should this resist clearing
out with the probe, the fire must be immediately withdrawn from the
furnace, otherwise the apparatus will probably burst or blow up. Care
must be taken to prevent any moisture getting into the nozzle, for it
would probably produce a violent detonation.

When the operation has proceeded regularly, accompanied to the end with
a constant evolution of gas, the retort becomes nearly empty, or
contains merely a little charcoal, or carbonate of potassa, and the
potassium collects in the naphtha at the bottom of the receiver E, in
the form of globules or rounded lumps, of greater or less size, and of a
leaden hue. But the greater part of the metal escapes with the gas, in a
state of combination not well understood. This gaseous compound burns
with a white or reddish-white flame, and deposits potassa. Several
ounces of potassium may be produced in this way at one operation; but,
as thus obtained, it always contains some combined charcoal, which must
be separated by distilling it in an iron retort, having its beak plunged
in naphtha.

Pure potassium, as procured in Sir H. Davy’s original method, by acting
upon fused potassa under a film of naphtha, with the negative wire of a
powerful voltaic battery, is very like quicksilver. It is semi-fluid at
60° Fahr., nearly liquid at 92°, and entirely so at 120°. At 50° it is
malleable, and has the lustre of polished silver; at 32° it is brittle,
with a crystalline fracture; and at a heat approaching to redness, it
begins to boil, is volatilized, and converted into a green-coloured gas,
which condenses into globules upon the surface of a cold body. Its
specific gravity in the purest state is 0·865 at 60°. When heated in the
air, it takes fire, and burns very vividly. It has a stronger affinity
for oxygen than any other known substance; and is hence very difficult
to preserve in the metallic state. At a high temperature it reduces
almost every oxygenated body. When thrown upon water, it kindles, and
moves about violently upon the surface, burning with a red flame, till
it be consumed; that is to say, converted into potassa. When thrown upon
a cake of ice, it likewise kindles, and burns a hole in it. If a globule
of it be laid upon wet turmeric paper, it takes fire, and runs about,
marking its desultory path with red lines. The flame observed in these
cases is owing chiefly to hydrogen, for it is at the expense of the
water that the potassium burns.

Potassa, even in a pretty dilute solution, produces a precipitate with
muriate of platinum, a phenomenon which distinguishes it from soda. It
forms, moreover, with sulphuric and acetic acids, salts which
crystallize very differently from the sulphates and acetates of soda.


POTTERY, PORCELAIN. (Eng. and Fr.; _Steingut_, _Porzellan_, Germ.) The
French, who are fond of giving far-fetched names to the most ordinary
things, have dignified the art of pottery with the title of _ceramique_,
from the Greek noun κεραμος, an earthen pot, compounded of two words
which signify, in that language, _burned clay_. In reference to chemical
constitution, there are only two genera of baked stoneware. The first
consists of a fusible earthy mixture, along with an infusible, which
when combined are susceptible of becoming semi-vitrified and translucent
in the kiln. This constitutes porcelain or china-ware; which is either
hard and genuine, or tender and spurious, according to the quality and
quantity of the fusible ingredient. The second kind consists of an
infusible mixture of earths, which is refractory in the kiln, and
continues opaque. This is pottery, properly so called; but it
comprehends several sub-species, which graduate into each other by
imperceptible shades of difference. To this head belong earthenware,
stoneware, flintware, _fayence_, delftware, iron-stone china, &c.

The earliest attempts to make a compact stoneware, with a painted glaze,
seem to have originated with the Arabians in Spain, about the 9th
century, and to have passed thence into Majorca, in which island they
were carried on with no little success. In the 14th century, these
articles, and the art of imitating them, were highly prized by the
Italians, under the name of Majolica, and _porcelana_, from the
Portuguese word for a cup. The first fabric of stoneware possessed by
them, was erected at Fayenza, in the ecclesiastical state, whence the
French term _fayence_ is derived. The body of the ware was usually a red
clay, and the glaze was opaque, being formed of the oxides of lead and
tin, along with potash and sand. Bernhard de Pallissy, about the middle
of the 16th century, manufactured the first white _fayence_, at Saintes,
in France; and not long afterwards the Dutch produced a similar article,
of substantial make, under the name of delftware, and delft _porcelain_,
but destitute of those graceful forms and paintings for which the ware
of Fayenza was distinguished. Common fayence may be, therefore, regarded
as a strong, well-burned, but rather coarse-grained kind of stoneware.

It was in the 17th century that a small work for making earthenware of a
coarse description, coated with a common lead glaze, was formed at
Burslem, in Staffordshire, which may be considered as the germ of the
vast potteries now established in that county. The manufacture was
improved about the year 1690, by two Dutchmen, the brothers Elers, who
introduced the mode of glazing ware by the vapour of salt, which they
threw by handfuls at a certain period among the ignited goods in the
kiln. But these were rude, unscientific, and desultory efforts. It is to
the late Josiah Wedgewood, Esq. that this country and the world at large
are mainly indebted for the great modern advancement of the _ceramic_
art. It was he who first erected magnificent factories, where every
resource of mechanical and chemical science was made to co-operate with
the arts of painting, sculpture, and statuary, in perfecting this
valuable department of the industry of nations. So sound were his
principles, so judicious his plans of procedure, and so ably have they
been prosecuted by his successors in Staffordshire, that a population of
60,000 operatives now derives a comfortable subsistence within a
district formerly bleak and barren, of 8 miles long, by 6 broad, which
contains 150 kilns, and is significantly called the Potteries.

OF THE MATERIALS OF POTTERY OR PORCELAIN, AND THEIR PREPARATION.

1. _Clay._--The best clay from which the Staffordshire ware is made,
comes from Dorsetshire; and a second quality from Devonshire: but both
are well adapted for working, being refractory in the fire, and becoming
very white when burnt. The clay is cleaned as much as possible by hand,
and freed from loosely adhering stones at the pits where it is dug. In
the factory mounted by Mr. Wedgewood, which may be regarded as a type of
excellence, the clay is cut to pieces, and then kneaded into a pulp with
water, by engines; instead of being broken down with pickaxes, and
worked with water by hand-paddles, in a square pit or water-tank, an old
process, called _blunging_. The clay is now thrown into a cast-iron
cylinder, 20 inches wide, and 4 feet high, or into a cone 2 feet wide at
top, and 6 feet deep, in whose axis an upright shaft revolves, bearing
knives as radii to the shaft. The knives are so arranged, that their
flat sides lie in the plane of a spiral line; so that by the revolution
of the shaft, they not only cut through every thing in their way, but
constantly press the soft contents of the cylinder or cone obliquely
downwards, on the principle of a screw. Another set of knives stands out
motionless at right angles from the inner surface of the cylinder, and
projects nearly to the central shaft, having their edges looking
opposite to the line of motion of the revolving blades. Thus the two
sets of slicing implements, the one active, and the other passive,
operate like shears in cutting the clay into small pieces, while the
active blades, by their spiral form, force the clay in its comminuted
state out at an aperture at the bottom of the cylinder or cone, whence
it is conveyed into a cylindrical vat, to be worked into a pap with
water. This cylinder is tub-shaped, being about 4 times wider than it is
deep. A perpendicular shaft turns also in the axis of this vat, bearing
cross spokes one below another, of which the vertical set on each side
is connected by upright staves, giving the movable arms the appearance
of two or four opposite square paddle-boards revolving with the shaft.
This wooden framework, or large blunger, as it is called, turns round
amidst the water and clay lumps, so as to beat them into a fine pap,
from which the stony and coarse sandy particles separate, and subside to
the bottom. Whenever the pap has acquired a cream-consistenced
uniformity, it is run off through a series of wire, lawn, and silk
sieves, of different degrees of fineness, which are kept in continual
agitation backwards and forward by a crank mechanism; and thus all the
grosser parts are completely separated, and hindered from entering into
the composition of the ware. This clay liquor is set aside in proper
cisterns, and diluted with water to a standard density.

2. But clay alone cannot form a proper material for stoneware, on
account of its great contractility by heat, and the consequent cracking
and splitting in the kiln of the vessels made of it; for which reason, a
siliceous substance incapable of contraction must enter into the body of
pottery. For this purpose, ground flints, called flint-powder by the
potters, is universally preferred. The nodules of flint extracted from
the chalk formation, are washed, heated redhot in a kiln, like that for
burning lime, and thrown in this state into water, by which treatment
they lose their translucency, and become exceeding brittle. They are
then reduced to a coarse powder in a stamping-mill, similar to that for
stamping ores; see METALLURGY. The pieces of flint are laid on a strong
grating, and pass through its meshes whenever they are reduced by the
stamps to a certain state of comminution. This granular matter is now
transferred to the proper flint-mill, which consists of a strong
cylindrical wooden tub, bottomed with flat pieces of massive _chert_, or
hornstone, over which are laid large flat blocks of similar chert, that
are moved round over the others by strong iron or wooden arms projecting
from an upright shaft made to revolve in the axis of the mill-tub.
Sometimes the active blocks are fixed to these cross arms, and thus
carried round over the passive blocks at the bottom. See _infrà_, under
PORCELAIN, figures of the flint and felspar mill. Into this cylindrical
vessel a small stream of water constantly trickles, which facilitates
the grinding motion and action of the stones, and works the flint powder
and water into a species of pap. Near the surface of the water there is
a plughole in the side of the tub, by which the creamy-looking flint
liquor is run off from time to time, to be passed through lawn or silk
sieves, similar to those used for the clay liquor; while the particles
that remain on the sieves are returned into the mill. This pap is also
reduced to a standard density by dilution with water; whence the weight
of dry siliceous earth present, may be deduced from the measure of the
liquor.

The standard clay and flint liquors are now mixed together, in such
proportion by measure, that the flint powder may bear to the dry clay
the ratio of one to five, or occasionally one to six, according to the
richness or plasticity of the clay; and the liquors are intimately
incorporated in a revolving churn, similar to that employed for making
the clay-pap. This mixture is next freed from its excess of water, by
evaporation in oblong stone troughs, called _slip-kilns_, bottomed with
fire-tiles, under which a furnace flue runs. The breadth of this
evaporating trough varies from 2 to 6 feet; its length from 20 to 50;
and its depth from 8 to 12 inches, or more.

By the dissipation of the water, and careful agitation of the pap, an
uniform doughy mass is obtained; which, being taken out of the trough,
is cut into cubical lumps. These are piled in heaps, and left in a damp
cellar for a considerable time; that is, several months, in large
manufactories. Here the dough suffers disintegration, promoted by a kind
of fermentative action, due probably to some vegetable matter in the
water and the clay; for it becomes black, and exhales a fetid odour.
The argillaceous and siliceous particles get disintegrated also by the
action of the water, in such a way that the ware made with old paste is
found to be more homogeneous, finer grained, and not so apt to crack or
to get disfigured in the baking, as the ware made with newer paste.

But this chemical comminution must be aided by mechanical operations;
the first of which is called the potter’s _sloping_ or _wedging_. It
consists in seizing a mass of clay in the hands, and, with a twist of
both at once, tearing it into two pieces, or cutting it with a wire.
These are again slapped together with force, but in a different
direction from that in which they adhered before, and then dashed down
on a board. The mass is once more torn or cut asunder at right angles,
again slapped together, and so worked repeatedly for 20 or 30 times,
which ensures so complete an incorporation of the different parts, that
if the mass had been at first half black and half white clay, it would
now be of a uniform gray colour. A similar effect is produced in some
large establishments by a slicing machine, like that used for cutting
down the clay lumps as they come from the pit.

In the axis of a cast iron cylinder or cone, an upright shaft is made to
revolve, from which the spiral-shaped blades extend, with their edges
placed in the direction of rotation. The pieces of clay subjected to the
action of these knives (with the reaction of fixed ones) are minced to
small morsels, which are forced pell-mell by the screw-like pressure
into an opening of the bottom of the cylinder or cone, from which a
horizontal pipe about 6 inches square proceeds. The dough is made to
issue through this outlet, and is then cut into lengths of about 12
inches. These clay pillars or prisms are thrown back into the cylinder,
and subjected to the same operation again and again, till the lumps have
their particles perfectly blended together. This process may
advantageously precede their being set aside to ripen in a damp cellar.
In France the stoneware dough is not worked in such a machine; but after
being beat with wooden mallets, a practice common also in England, it is
laid down on a clean floor, and a workman is set to tread upon it with
naked feet for a considerable time, walking in a spiral direction from
the centre to the circumference, and from the circumference to the
centre. In Sweden, and also in China (to judge from the Chinese
paintings which represent their manner of making porcelain), the clay is
trodden to a uniform mass by oxen. It is afterwards, in all cases,
kneaded like baker’s dough, by folding back the cake upon itself, and
kneading it out, alternately.

The process of _slapping_ consists in cutting through a large mass with
a wire, lifting up either half in both hands, and casting it down with
great violence on the other; and this violent treatment of the clay is
repeated till every appearance of air-bubbles is removed, for the
smallest remaining vesicle expanding in the kiln, would be apt to cause
blisters or warts upon the ware.

Having thus detailed the preparation of the stoneware paste, we have
next to describe the methods of forming it into articles of various
forms.

_Throwing_ is performed upon a tool called the potter’s lathe. (See
fig., _infrà._) This consists of an upright iron shaft, about the height
of a common table, on the top of which is fixed, by its centre, a
horizontal disc or circular piece of wood, of an area sufficiently great
for the largest stoneware vessel to stand upon. The lower end of the
shaft is pointed, and runs in a conical step, and its collar, a little
below the top-board, being truly turned, is embraced in a socket
attached to the wooden frame of the lathe. The shaft has a pulley fixed
upon it, with grooves for 3 speeds, over which an endless band passes
from a fly-wheel, by whose revolution any desired rapidity of rotation
may be given to the shaft and its top-board. This wheel, when small, may
be placed alongside, as in the turner’s lathe, and then it is driven by
a treadle and crank; or when of larger dimensions, it is turned by the
arms of a labourer. Sometimes, indeed, the wooden plate is replaced by a
large thick disc of Paris plaster, which is whirled round by the hand of
the potter, without the intervention of a pulley and fly-wheel, and
affords sufficient centrifugal power for fashioning small vessels. The
mass of dough to be thrown, is weighed out or gauged by an experienced
hand. The thrower dashes down the lump on the centre of the revolving
board, and dipping his hands frequently in an adjoining tub of water, he
works up the clay into a tall irregular cylinder, and then down into a
cake, alternately, till he has secured the final extrication of
air-bubbles, and then gives the proper form to the vessel under a less
speed of rotation, regulating its dimensions by wooden pegs and gauges.
He now cuts it off at the base with a piece of fine brass wire, fastened
to a handle at either end. The vessel thus rudely fashioned is placed in
a situation where it may dry gradually to a proper point. At a certain
stage of the drying, called the _green state_, it possesses a greater
tenacity than at any other, till it is baked. It is then taken to
another lathe, called the turning lathe, where it is attached by a
little moisture to the vertical face of a wooden chuck, and turned
nicely into its proper shape with a very sharp tool, which also smooths
it. After this it is slightly burnished with a smooth steel surface.

DESCRIPTION OF THE POTTER’S LATHE.

[Illustration: 891]

A, _fig._ 891., is the profile of the English potter’s lathe, for
blocking out round ware; C is the table or tray; _a_ is the head of the
lathe, with its horizontal disc; _a_, _b_, is the upright shaft of the
head; _d_, pulleys with several grooves of different diameters, fixed
upon the shaft, for receiving the driving-cord or band; _k_ is a bench
upon which the workman sits astride; _e_, the treadle foot-board; _l_,
is a ledge-board, for catching the shavings of clay which fly off from
the lathe; _h_ is an instrument, with a slide-nut _i_, for measuring the
objects in the blocking out; _c_ is the fly-wheel with its winch-handle
_r_, turned by an assistant; the sole-frame is secured in its place by
the heavy stone _p_; _f_ is the oblong guide-pulley, having also several
grooves for converting the vertical movement of the fly-wheel into the
horizontal movement of the head of the lathe.

D is one of the intermediate forms given by the potter to the ball of
clay, as it revolves upon the head of the lathe.

In large potteries, the whole of the lathes, both for throwing and
turning, are put in motion by a steam-engine. The vertical spindle of
the lathe has a bevel wheel on it, which works in another bevel toothed
wheel fixed to a horizontal shaft. This shaft is provided with a long
conical wooden drum, from which a strap ascends to a similar conical
drum on the main lying shaft. The apex of the one cone corresponds to
the base of the other, which allows the strap to retain the same degree
of tension (see the conical drum apparatus of the _Stearine-press_),
while it is made to traverse horizontally, in order to vary the speed of
the lathe at pleasure. When the belt is at the base of the driving-cone,
it works near the vortex of the driven one, so as to give a maximum
velocity to the lathe, and _vice versâ_.

During the throwing of any article, a separate mechanism is conducted by
a boy, which makes the strap move parallel to itself along these conical
drums, and nicely regulates the speed of the lathe. When the strap runs
at the middle of the cones, the velocity of each shaft is equal. By this
elegant contrivance of parallel cones reversed, the velocity rises
gradually to its maximum, and returns to its minimum or slower motion
when the workman is about finishing the article thrown. The strap is
then transferred to a pair of loose pulleys, and the lathe stops. The
vessel is now cut off at the base with a small wire; is dried, turned on
a power lathe, and polished as above described.

The same degree of dryness which admits of the clay being turned on the
lathe, also suits for fixing on the handles and other appendages to the
vessels. The parts to be attached being previously prepared, are joined
to the circular work by means of a thin paste which the workmen call
_slip_, and the seams are then smoothed off with a wet sponge. They are
now taken to a stove-room heated to 80° or 90° F., and fitted up with a
great many shelves. When they are fully dried, they are smoothed over
with a small bundle of hemp, if the articles be fine, and are then ready
for the kiln, which is to convert the tender clay into the hard
_biscuit_.

A great variety of pottery wares, however, cannot be fashioned on the
lathe, as they are not of a circular form. These are made by two
different methods, the one called _press-work_, and the other _casting_.
The press-work is done in moulds made of Paris plaster, the one half of
the pattern being formed in the one side of the mould, and the other
half on the other side: these moulding-pieces fit accurately together.
All vessels of an oval form, and such as have flat sides, are made in
this way. Handles of tea-pots, and fluted solid rods of various shapes,
are formed by pressure also; viz., by squeezing the dough contained in a
pump-barrel through different shaped orifices at its bottom, by working
a screw applied to the piston-rod. The worm-shaped dough, as it issues,
is cut to proper lengths, and bent into the desired form. Tubes may be
also made on the same pressure principle, only a tubular opening must be
provided in the bottom plate of the clay-forcing pump. The other method
of fashioning earthenware articles is called _casting_, and is, perhaps,
the most elegant for such as have an irregular shape. This operation
consists in pouring the clay, in the state of pap or slip, into plaster
moulds, which are kept in a desiccated state. These moulds, as well as
the pressure ones, are made in halves, which nicely correspond together.
The slip is poured in till the cavity is quite full, and is left in the
mould for a certain time, more or less, according to the intended
thickness of the vessel. The absorbent power of the plaster soon
abstracts the water, and makes the coat of clay in contact with it quite
doughy and stiff, so that the part still liquid being poured out, a
hollow shape remains, which when removed from the mould constitutes the
half of the vessel, bearing externally the exact impress of the mould.
The thickness of the clay varies with the time that the paste has stood
upon the plaster. These _cast_ articles are dried to the green state,
like the preceding, and then joined accurately with _slip_. Imitations
of flowers and foliage are elegantly executed in this way. This
operation, which is called _furnishing_, requires very delicate and
dexterous manipulation.

The saggers for the unglazed coloured stoneware should be covered inside
with a glaze composed of 12 parts of common salt and 30 of potash, or 6
parts of potash and 14 of salt; which may be mixed with a little of the
common enamel for the glazed pottery saggers. The bottom of each sagger
has some bits of flints sprinkled upon it, which become so adherent
after the first firing as to form a multitude of little prominences for
setting the ware upon, when this does not consist of plates. It is the
duty of the workmen belonging to the glaze kiln to make the saggers
during the intervals of their work; or if there be a relay of hands, the
man who is not firing makes the saggers.

The English kilns differ from those of France and Germany, in their
construction, in the nature of their fuel, and in the high temperature
required to produce a surface sufficiently hard for a perfectly fine
glaze.

When the ware is sufficiently dry, and in sufficient quantity to fill a
kiln, the next process is placing the various articles in the baked
fire-clay vessels, which may be either of a cylindrical or oval shape;
called _gazettes_, Fr.; _kapseln_, Germ. These are from 6 to 8 inches
deep, and from 12 to 18 inches in diameter. When packed full of the dry
ware, they are piled over each other in the kiln. The bottom of the
upper sagger forms the lid of its fellow below; and the junction of the
two is luted with a ring of soft clay applied between them. These dishes
protect the ware from being suddenly and unequally heated, and from
being soiled by the smoke and vapours of the fuel. Each pile of saggers
is called a _bung_.

POTTERY KILN OF STAFFORDSHIRE.

[Illustration: 892 893 894]

_Figs._ 892, 893, 894, 895, 896., represent the kiln for baking the
biscuit, and also for running the glaze, in the English potteries.

_a_, _a_, _figs._ 892, 893, and 894, are the furnaces which heat the
kiln; of which _b_, in _fig._ 892., are the upper mouths, and _b´_ the
lower; the former being closed more or less by the fire-tile _z_, shown
in _fig._ 896.

_f_ is one fireplace; for the manner of distributing the fuel in it, see
_fig._ 896.

_g_, _y_, _figs._ 892. and 896., are the horizontal and vertical flues
and chimneys for conducting the flame and smoke. _l_ is the laboratory,
or body of the kiln; having its floor _k_ sloping slightly downwards
from the centre to the circumference. _x_, _y_, is the slit of the
horizontal register, leading to the chimney flue _y_ of the furnace,
being the first regulator; _x_, _u_, is the vertical register conduit,
leading to the furnace or mouth _f_, being the second regulator; _v_ is
the register slit above the furnace, and its vertical flue leading into
the body of the kiln; _v´_, _c_, slit for regulating flue at the
shoulder of the kiln; _i_ is an arch which supports the walls of the
kiln, when the furnace is under repair; _c_, _c_, are small flues in the
vault _s_ of the laboratory. _h_, _fig._ 893., is the central flue,
called _lunette_, of the laboratory.

T, T, is the conical tower or _howell_, strengthened with a series of
iron hoops, O´ is the great chimney or _lunette_ of the tower; _p_ is
the door of the laboratory, bound inside with an iron frame.

A, is the complete kiln and _howell_, with all its appurtenances.

B, _fig._ 893., is the plan at the level _d_, _d_, of the floor, to show
the arrangement and distribution of all the horizontal flues, both
circular and radiating.

C, _fig._ 894., is a plan at the level _e_, _e_, of the upper mouths
_b_, of the furnaces, to show the disposition of the fireplaces of the
vertical flues, and of the horizontal registers, or peep-holes.

D, _fig._ 894., is a bird’s-eye view of the top of the vault or dome
_s_, to show the disposition of the vent-holes _c_, _c_.

[Illustration: 895 896]

E, _fig._ 895., is a detailed plan at the level _c_, _c_, of one furnace
and its dependencies.

F, _fig._ 896., is a transverse section, in detail, of one furnace and
its dependencies.

The same letters in all the figures indicate the same objects.

_Charging of the kiln._--The saggers are piled up first in the space
between each of the upright furnaces, till they rise to the top of the
flues. These contain the smaller articles. Above this level, large fire
tiles are laid, for supporting other saggers, filled with teacups,
sugar-basins, &c. In the bottom part of the pile, within the preceding,
the same sorts of articles are put; but in the upper part all such
articles are placed as require a high heat. Four piles of small saggers,
with a middle one 10 inches in height, complete the charge. As there are
6 piles between each furnace, and as the biscuit kiln has 8 furnaces, a
charge consequently amounts to 48 or 50 _bungs_, each composed of from
18 to 19 saggers. The inclination of the bungs ought always to follow
the form of the kiln, and should therefore tend towards the centre, lest
the strong draught of the furnaces should make the saggers fall against
the walls of the kiln, an accident apt to happen were these piles
perpendicular. The last sagger of each bung is covered with an unbaked
one, three inches deep, in place of a round lid. The watches are small
cups, of the same biscuit as the charge, placed in saggers, four in
number, above the level of the flue-tops. They are taken hastily out of
the saggers, lest they should get smoked, and are thrown into cold
water.

When the charging is completed, the firing is commenced, with coal of
the best quality. The management of the furnaces is a matter of great
consequence to the success of the process. No greater heat should be
employed for some time than may be necessary to agglutinate the
particles which enter into the composition of the paste, by evaporating
all the humidity; and the heat should never be raised so high as to
endanger the fusion of the ware, which would make it very brittle.

When ever the mouth or door of the kiln is built up, a child prepares
several fires in the neighbourhood of the _howell_, while a labourer
transports in a wheelbarrow a supply of coals, and introduces into each
furnace a number of lumps. These lumps divide the furnace into two
parts; those for the upper flues being placed above, and those for the
ground flues below, which must be kept unobstructed.

The fire-mouths being charged, they are kindled to begin the baking, the
regulator tile _z_, _fig._ 896., being now opened; an hour afterwards
the bricks at the bottom of the furnace are stopped up. The fire is
usually kindled at 6 o’clock in the evening, and progressively increased
till 10, when it begins to gain force, and the flame rises half-way up
the chimney. The second charge is put in at 8 o’clock, and the mouths of
the furnaces are then covered with tiles; by which time the flame issues
through the vent of the tower. An hour afterwards a fresh charge is
made; the tiles _z_, which cover the furnaces, are slipped back; the
cinders are drawn to the front, and replaced with small coal. About
half-past 11 o’clock the kiln-man examines his furnaces, to see that
their draught is properly regulated. An hour afterwards a new charge of
coal is applied; a practice repeated hourly till 6 o’clock in the
morning. At this moment he takes out his first _watch_, to see how the
baking goes on. It should be at a very pale-red heat; but the watch of 7
o’clock should be a deeper red. He removes the tiles from those furnaces
which appear to have been burning too strongly, or whose flame issues by
the orifices made in the shoulder of the kiln; and puts tiles upon those
which are not hot enough. The flames glide along briskly in a regular
manner. At this period he draws out the watches every quarter of an
hour, and compares them with those reserved from a previous standard
kiln; and if he observes a similarity of appearance, he allows the
furnaces to burn a little longer; then opens the mouths carefully and by
slow degrees; so as to lower the heat, and finish the round.

The baking usually lasts from 40 to 42 hours; in which time the biscuit
kiln may consume 14 tons of coals; of which four are put in the first
day, seven the next day and following night, and the four last give the
strong finishing heat.

_Emptying the kiln._--The kiln is allowed to cool very slowly. On taking
the ware out of the saggers, the biscuit is not subjected to friction,
as in the foreign potteries, because it is smooth enough; but is
immediately transported to the place where it is to be dipped in the
glaze or enamel tub. A child makes the pieces ring, by striking with the
handle of the brush, as he dusts them, and then immerses them into the
glaze cream; from which tub they are taken out by the enameller, and
shaken in the air. The tub usually contains no more than 4 or 5 inches
depth of the glaze, to enable the workman to pick out the articles more
readily, and to lay them upon a board, whence they are taken by a child
to the glaze kiln.

_Glazing._--A good enamel is an essential element of fine stoneware; it
should experience the same dilatation and contraction by heat and cold
as the biscuit which it covers. The English enamels contain nothing
prejudicial to health, as many of the foreign glazes do; no more lead
being added to the former than is absolutely necessary to convert the
siliceous and aluminous matters with which it is mixed into a perfectly
neutral glass.

Three kinds of glazes are used in Staffordshire; one for the common
pipe-clay or cream-coloured ware; another for the finer pipe-clay ware
to receive impressions, called _printing body_; a third for the ware
which is to be ornamented by painting with the pencil.

The glaze of the first or common ware is composed of 53 parts of white
lead, 16 of Cornish stone, 36 of ground flints, and 4 of flint glass; or
of 40 of white lead, 36 of Cornish stone, 12 of flints, and 4 of flint
or crystal glass. These compositions are not fritted; but are employed
after being simply triturated with water into a thin paste.

The following is the composition of the glaze intended to cover all
kinds of figures printed in metallic colours: 26 parts of white felspar
are fritted with 6 parts of soda, 2 of nitre, and 1 of borax; to 20
pounds of this frit, 26 parts of felspar, 20 of white lead, 6 of ground
flints, 4 of chalk, 1 of oxide of tin, and a small quantity of oxide of
cobalt, to take off the brown cast, and give a faint azure tint, are
added.

The following recipe may also be used. Frit together 20 parts of flint
glass, 6 of flints, 2 of nitre, and 1 of borax; add to 12 parts of that
frit, 40 parts of white lead, 36 of felspar, 8 of flints, and 6 of flint
glass; then grind the whole together into an uniform cream-consistenced
paste.

As to the stoneware which is to be painted, it is covered with a glaze
composed of 13 parts of the printing-colour frit, to which are added 50
parts of red lead, 40 of white lead, and 12 of flint; the whole having
been ground together.

The above compositions produce a very hard glaze, which cannot be
scratched by the knife, is not acted upon by vegetable acids, and does
no injury to potable or edible articles kept in the vessels covered with
it. It preserves for an indefinite time the glassy lustre, and is not
subject to crack and exfoliate, like most of the Continental stoneware,
made from common pipe-clay.

In order that the saggers in which the articles are baked, after
receiving the glaze, may not absorb some of the vitrifying matter, they
are themselves coated, as above mentioned, with a glaze composed of 13
parts of common salt, and 30 parts of potash, simply dissolved in water,
and brushed over them.

_Glaze kiln._--This is usually smaller than the biscuit kiln, and
contains no more than 40 or 45 bungs or columns, each composed of 16 or
17 saggers. Those of the first bung rest upon round tiles, and are well
luted together with a finely ground fire-clay of only moderate cohesion;
those of the second bung are supported by an additional tile. The lower
saggers contain the cream-coloured articles, in which the glaze is
softer than that which covers the blue printed ware; this being always
placed in the intervals between the furnaces, and in the uppermost
saggers of the columns. The bottom of the kiln, where the glazed ware is
not baked, is occupied by printed biscuit ware.

Pyrometric balls of red clay, coated with a very fusible lead enamel,
are employed in the English potteries to ascertain the temperature of
the glaze kilns. This enamel is so rich, and the clay upon which it is
spread, is so fine-grained and compact, that even when exposed for three
hours to the briskest flame, it does not lose its lustre. The colour of
the clay alone changes, whereby the workman is enabled to judge of the
degree of heat within the kiln. At first the balls have a pale red
appearance; but they become browner with the increase of the
temperature. The balls, when of a slightly dark-red colour, indicate the
degree of baking for the hard glaze of pipeclay ware; but if they become
dark brown, the glaze will be much too hard, being that suited for
_ironstone_ ware; lastly, when they acquire an almost black hue, they
show a degree of heat suited to the formation of a glaze upon porcelain.

The _glazer_ provides himself at each round with a stock of these ball
_watches_, reserved from the preceding baking, to serve as objects of
comparison; and he never slackens the firing till he has obtained the
same depth of shade, or even somewhat more; for it may be remarked, that
the more rounds a glaze kiln has made, the browner the balls are apt to
become. A new kiln bakes a round of enamel-ware sooner than an old one;
as also with less fuel, and at a lower temperature. The watch-balls of
these first rounds have generally not so deep a colour as if they were
tried in a furnace three or four months old. After this period, cracks
begin to appear in the furnaces; the horizontal flues get partially
obstructed, the joinings of the brickwork become loose; in consequence
of which there is a loss of heat and waste of fuel; the baking of the
glaze takes a longer time, and the pyrometric balls assume a different
shade from what they had on being taken out of the new kiln, so that the
first watches are of no comparable use after two months. The baking of
enamel is commenced at a low temperature, and the heat is progressively
increased; when it reaches the melting point of the glaze, it must be
maintained steadily, and the furnace mouths be carefully looked after,
lest the heat should be suffered to fall. The firing is continued 14
hours, and then gradually lowered by slight additions of fuel; after
which the kiln is allowed from 5 to 6 hours to cool.

[Illustration: 897 898]

_Muffles._--The paintings and the printed figures applied to the glaze
of stoneware and porcelain are baked in muffles of a peculiar form.
_Fig._ 897. is a lateral elevation of one of these muffles; _fig._ 898.
is a front view. The same letters denote the same parts in the two
figures.

_a_ is the furnace; _b_, the oblong muffle, made of fire-clay,
surmounted with a dome pierced with three apertures _k_, _k_, _k_, for
the escape of the vaporous matters of the colours and volatile oils with
which they are ground up; _c_ is the chimney; _d_, _d_, feed-holes, by
which the fuel is introduced; _e_, the fire-grate; _f_, the ash-pit;
channels are left in the bottom of the furnace to facilitate the passage
of the flame beneath the muffle; _g_ is a lateral hole, which makes a
communication across the furnace in the muffle, enabling the kiln man to
ascertain what is passing within; _k_, _k_, are the lateral chinks for
observing the progress of the firing or flame; _l_, is an opening
scooped out in the front of the chimney to modify its draught.

The articles which are printed or painted upon the glaze are placed in
the muffle without saggers, upon tripods, or movable supports furnished
with feet. The muffle being charged, its mouth is closed with a
fire-tile well luted round its edges. The fuel is then kindled in the
fireplaces _d_, _d_, and the door of the furnace is closed with bricks,
in which a small opening is left for taking out samples, and for
examining the interior of the muffle. These sample or trial pieces,
attached to a strong iron wire, show the progress of the baking
operation. The front of the fireplaces is covered with a sheet-iron
plate, which slides to one side, and may be shut whenever the kiln is
charged. Soon after the fire is lighted, the flame, which communicates
laterally from one furnace to another, envelopes the muffle on all
sides, and thence rises up the chimney.

_Printing of stoneware._--The printing under the stoneware glaze is
generally performed by means of cobalt, and has different shades of blue
according to the quantity of colouring matter employed. After having
subjected this oxide to the processes requisite for its purification, it
is mixed with a certain quantity of ground flints and sulphate of
baryta, proportioned to the dilution of the shade. These materials are
fritted and ground; but before they are used, they must be mixed with a
flux consisting of equal parts by weight of flint glass and ground
flints, which serves to fix the colour upon the biscuit, so that the
immersion in the glaze liquor may not displace the lines printed on, as
also to aid in fluxing the cobalt.

The following are the processes usually practised in Staffordshire for
printing under the glaze.

The cobalt, or whatever colour is employed, should be ground upon a
porphyry slab, with a varnish prepared as follows:--A pint of linseed
oil is to be boiled to the consistence of thick honey, along with 4
ounces of rosin, half a pound of tar, and half a pint of oil of amber.
This is very tenacious, and can be used only when liquefied by heat;
which the printer effects by spreading it upon a hot cast-iron plate.

The printing plates are made of copper, engraved with pretty deep lines
in the common way. The printer, with a leather muller, spreads upon the
engraved plate, previously heated, his colour, mixed up with the above
oil varnish, and removes what is superfluous with a pallet knife; then
cleans the plate with a dossil filled with bran, tapping and wiping as
if he were removing dust from it. This operation being finished, he
takes the paper intended to receive the impression, soaks it with
soap-water, and lays it moist upon the copper-plate. The soap makes the
paper part more readily from the copper, and the thick ink part more
readily from the biscuit. The copper-plate is now passed through the
engraver’s cylinder press, the proof leaf is lifted off and handed to
the women, who cut it into detached pieces, which they apply to the
surface of the biscuit. The paper best fitted for this purpose is made
entirely of linen rags; it is very thin, of a yellow colour, and
unsized, like tissue blotting-paper.

The stoneware biscuit never receives any preparation before being
imprinted, the oil of the colour being of such a nature as to fix the
figures firmly. The printed paper is pressed and rubbed on with a roll
of flannel, about an inch and a half in diameter, and 12 or 15 inches
long, bound round with twine, like a roll of tobacco. This is used as a
burnisher, one end of it being rested against the shoulder, and the
other end being rubbed upon the paper; by which means it transfers all
the engraved traces to the biscuit. The piece of biscuit is laid aside
for a little, in order that the colour may take fast hold; it is then
plunged into water, and the paper is washed away with a sponge.

When the paper is detached, the piece of ware is dipped into a caustic
alkaline lye to saponify the oil, after which it is immersed in the
glaze liquor, with which the printed figures readily adhere. This
process, which is easy to execute, and very economical, is much
preferable to the old plan of passing the biscuit into the muffle after
it had been printed, for the purpose of fixing and volatilizing the
oils. When the paper impression is applied to pieces of porcelain, they
are heated before being dipped in the water, because, being already
semi-vitrified, the paper sticks more closely to them than to the
biscuit, and can be removed only by a hard brush.

The impression above the glaze is done by quite a different process,
which dispenses with the use of the press. A quantity of fine clean glue
is melted and poured hot upon a large flat dish, so as to form a layer
about a quarter of an inch thick, and of the consistence of jelly. When
cold it is divided into cakes of the size of the copper-plates it is
intended to cover.

The operative (a woman) rubs the engraved copper-plate gently over with
linseed oil boiled thick, immediately after which she applies the cake
of glue, which she presses down with a silk dossil filled with bran. The
cake licks up all the oil out of the engraved lines; it is then
cautiously lifted off, and transferred to the surface of the glazed ware
which it is intended to print. The glue cake being removed, the enamel
surface must be rubbed with a little cotton, whereby the metallic
colours are attached only on the lines charged with oil; the piece is
then heated under the muffle. The same cake of glue may serve for
several impressions.

_Ornaments and colouring._--Common stoneware is coloured by means of two
kinds of apparatus; the one called the blowing-pot, the other the
worming-pot. The ornaments made in relief in France, are made hollow
(intaglio) in England, by means of a mould engraved in relief, which is
passed over the article. The impression which it produces is filled with
a thick clay paste, which the workman throws on with the blowing-pot.
This is a vessel like tea-pot, having a spout, but it is hermetically
sealed at top with a clay plug, after being filled with the pasty
liquor. The workman, by blowing in at the spout, causes the liquor to
fly out through a quill pipe which goes down through the clay plug into
the liquor. The jet is made to play upon the piece while it is being
turned upon the lathe; so that the hollows previously made in it by the
mould or stamp are filled with a paste of a colour different from that
of the body. When the piece has acquired sufficient firmness to bear
working, the excess of the paste is removed by an instrument called a
_tournasin_, till the ornamental figure produced by the stamp be laid
bare; in which case merely the colour appears at the bottom of the
impression. By passing in this manner several layers of clay liquor of
different colours over each other with the blowing-pot, net-work and
decorations of different colours and shades are very rapidly produced.

The serpentine or snake pots, established on the same principle, are
made of tin plate in three compartments, each containing a different
colour. These open at the top of the vessel in a common orifice,
terminated by small quill tubes. On inclining the vessel, the three
colours flow out at once in the same proportion at the one orifice, and
are let fall upon the piece while it is being slowly turned upon the
lathe; whereby curious serpent-like ornaments may be readily obtained.
The clay liquor ought to be in keeping with the stoneware paste. The
blues succeed best when the ornaments are made with the finer pottery
mixtures given above.

_Metallic lustres applied to stoneware._--The metallic lustre being
applied only to the outer surface of vessels, can have no bad effect on
health, whatever substances be employed for the purpose; and as the
glaze intended to receive it is sufficiently fusible, from the quantity
of lead it contains, there is no need of adding a flux to the metallic
coating. The glaze is in this case composed of 60 parts of litharge, 36
of felspar, and 15 of flints.

The silver and platina lustres are usually laid upon a white ground,
while those of gold and copper, on account of their transparency,
succeed only upon a coloured ground. The dark-coloured stoneware is,
however, preferable, as it shows off the colours to most advantage; and
thus the shades may be varied by varying the colours of the ornamental
figures applied by the blowing-pot.

The gold and platina lustre is almost always applied to a paste body
made on purpose, and coated with the above-described lead glaze. This
paste is brown, and consists of 4 parts of clay, 4 parts of flints, an
equal quantity of kaolin (china clay), and 6 parts of felspar. To make
brown figures in relief upon a body of white paste, a liquor is mixed up
with this paste, which ought to weigh 26 ounces per pint, in order to
unite well with the other paste, and not to exfoliate after it is baked.

_Preparation of gold lustre._--Dissolve first in the cold, and then with
heat, 48 grains of fine gold in 288 grains of an aqua regia, composed of
1 ounce of nitric acid and 3 ounces of muriatic acid; add to that
solution 4-1/2 grains of grain tin, bit by bit; and then pour some of
that compound solution into 20 grains of balsam of sulphur diluted with
10 grains of oil of turpentine. The balsam of sulphur is prepared by
heating a pint of linseed oil, and 2 ounces of flowers of sulphur,
stirring them continually till the mixture begins to boil; it is then
cooled, by setting the vessel in cold water; after which it is stirred
afresh, and strained-through linen. The above ingredients, after being
well mixed, are to be allowed to settle for a few minutes; then the
remainder of the solution of gold is to be poured in, and the whole is
to be triturated till the mass has assumed such a consistence that the
pestle will stand upright in it; lastly, there must be added to the
mixture 30 grains of oil of turpentine, which being ground in, the gold
lustre is ready to be applied. If the lustre is too light or pale, more
gold must be added, and if it have not a sufficiently violet or purple
tint, more tin must be used.

_Platina lustre._--Of this there are two kinds; one similar to polished
steel, another lighter and of a silver-white hue. To give stoneware the
steel colour with platina, this metal must be dissolved in an aqua regia
composed of 2 parts of muriatic acid, and 1 part of nitric. The solution
being cooled, and poured into a capsule, there must be added to it, drop
by drop, with continual stirring with a glass rod, a _spirit of tar_,
composed of equal parts of tar and sulphur boiled in linseed oil and
filtered. If the platina solution be too strong, more spirit of tar must
be added to it; but if too weak, it must be concentrated by boiling.
Thus being brought to the proper pitch, the mixture may be spread ever
the piece, which being put into the muffle, will take the aspect of
steel.

The oxide of platina, by means of which the silver lustre is given to
stoneware, is prepared as follows:--After having dissolved to saturation
the metal in an aqua regia composed of equal parts of nitric and
muriatic acid, the solution is to be poured into a quantity of boiling
water. At the same time, a capsule, containing solution of sal-ammoniac
is placed upon a sand-bath, and the platina solution being poured into
it, the metal will fall down in the form of the well-known yellow
precipitate, which is to be washed with cold water till it is perfectly
edulcorated, then dried, and put up for use.

This metallic lustre is applied very smoothly by means of a flat camel’s
hair brush. It is then to be passed through the muffle kiln; but it
requires a second application of the platinum to have a sufficient body
of lustre. The articles sometimes come black out of the kiln, but they
get their proper appearance by being rubbed with cotton.

_Platina_ and _gold lustre_; by other recipes.

_Platina lustre._--Dissolve 1 ounce of platinum in aqua regia formed of
2 parts of muriatic acid and 1 part of nitric acid, with heat upon a
sand-bath, till the liquid is reduced to two-thirds of its volume; let
it cool; decant into a clean vessel, and pour into it, drop by drop,
with constant stirring, some distilled tar, until such a mixture is
produced as will give a good result in a trial upon the ware in the
kiln. If the lustre be too intense, more tar must be added; if it be too
weak, the mixture must be concentrated by further evaporation.

_Gold lustre._--Dissolve four shillings’ worth of gold in aqua regia
with a gentle heat. To the solution, when cool, add 2 grains of grain
tin, which will immediately dissolve. Prepare a mixture of half an ounce
of balsam of sulphur with a little essence of turpentine, beating them
together till they assume the appearance of milk. Pour this mixture into
the solution of gold and tin, drop by drop, with continual stirring; and
place the whole in a warm situation for some time.

It is absolutely necessary to apply this lustre only upon an enamel or
glaze which has already passed through the fire, otherwise the sulphur
would tarnish the composition.

These lustres are applied with most advantage upon chocolate and other
dark grounds. Much skill is required in their firing, and a perfect
acquaintance with the quality of the glaze on which they are applied.

_An iron lustre_, is obtained by dissolving a bit of steel or iron in
muriatic acid, mixing this solution with the spirit of tar, and applying
it to the surface of the ware.

_Aventurine glaze._--Mix a certain quantity of silver leaf with the
above-described soft glaze, grind the mixture along with some honey and
boiling water, till the metal assume the appearance of fine particles of
sand. The glaze being naturally of a yellowish hue, gives a golden tint
to the small fragments of silver disseminated through it. Molybdena may
also be applied to produce the aventurine aspect.

_The granite-like gold lustre_, is produced by throwing lightly with a
brush a few drops of oil of turpentine upon the goods already covered
with the preparation for gold lustre. These cause it to separate and
appear in particles resembling the surface of granite. When marbling is
to be given to stoneware, the lustres of gold, platina, and iron are
used at once, which blending in the fusion, form veins like those of
marble.

_Pottery and stoneware of the Wedgewood colour._--This is a kind of
semi-vitrified ware, called _dry bodies_, which is not susceptible of
receiving a superficial glaze. This pottery is composed in two ways: the
first is with barytic earths, which act as fluxes upon the clays, and
form enamels: thus the Wedgewood _jasper_ ware is made.

The white vitrifying pastes, fit for receiving all sorts of metallic
colours, are composed of 47 parts of sulphate of barytes, 15 of felspar,
26 of Devonshire clay, 6 of sulphate of lime, 15 of flints, and 10 of
sulphate of strontites. This composition is capable of receiving the
tints of the metallic oxides and of the ochrous metallic earths.
Manganese produces the dark purple colour; gold precipitated by tin, a
rose colour; antimony, orange; cobalt, different shades of blue; copper
is employed for the browns and the dead-leaf greens; nickel gives, with
potash, greenish colours.

One per cent. of oxide of cobalt is added; but one half, or even one
quarter, of a per cent. would be sufficient, to produce the fine
Wedgewood blue, when the nickel and manganese constitute 3 per cent. as
well as the carbonate of iron. For the blacks of this kind, some English
manufacturers mix black oxide of manganese with the black oxide of iron,
or with ochre. Nickel and umber afford a fine brown. Carbonate of iron,
mixed with bole or _terra di Sienna_, gives a beautiful tint to the
paste; as also manganese with cobalt, or cobalt with nickel. Antimony
produces a very fine colour when combined with the carbonate of iron in
the proportion of 2 per cent., along with the ingredients necessary to
form the above-described vitrifying paste.

The following is another vitrifying paste, of a much softer nature than
the preceding. Felspar, 30 parts; sulphate of lime, 23; silex, 17;
potter’s clay, 15; kaolin of Cornwall (china clay), 15; sulphate of
baryta, 10.

These vitrifying pastes are very plastic, and may be worked with as much
facility as English pipe-clay. The round ware is usually turned upon the
lathe. It may, however, be moulded, as the oval pieces always are. The
more delicate ornaments are cast in hollow moulds of baked clay, by
women and children, and applied with remarkable dexterity upon the
turned and moulded articles. The coloured pastes have such an affinity
for each other, that the detached ornaments may be applied not only with
a little gum water upon the convex and concave forms, but they may be
made to adhere without experiencing the least cracking or chinks. The
coloured pastes receive only one fire, unless the inner surface is to be
glazed; but a gloss is given to the outer surface. The enamel for the
interior of the black Wedgewood ware, is composed of 6 parts of red
lead, 1 of silex, and 2 ounces of manganese, when the mixture is made in
pounds’ weight.

The operation called _smearing_, consists in giving an external lustre
to the unglazed semi-vitrified ware. The articles do not in this way
receive any immersion, nor even the aid of the brush or pencil of the
artist; but they require a second fire. The saggers are coated with the
salt glaze already described. These cases, or saggers, communicate by
reverberation the lustre so remarkable on the surface of the English
stoneware; which one might suppose to be the result of the glaze tub, or
of the brush. Occasionally also a very fusible composition is thrown
upon the inner surface of the muffle, and 5 or 6 pieces called
_refractories_ are set in the middle of it, coated with the same
composition. The intensity of the heat converts the flux into vapour; a
part of this is condensed upon the surfaces of the contiguous articles,
so as to give them the desired brilliancy.

_Mortar body_, is a paste composed of 6 parts of clay, 3 of felspar, 2
of silex, and 1 of china clay.

White and yellow figures upon dark-coloured grounds are a good deal
employed. To produce yellow impressions upon brown stoneware, ochre is
ground up with a small quantity of antimony. The flux consists of flint
glass and flints in equal weights. The composition for white designs is
made by grinding silex up with that flux, and printing it on, as for
blue colours, upon brown or other coloured stoneware, which shows off
the light hues.

_English porcelain or china._--Most of this belongs to the class called
tender or soft porcelain by the French and German manufacturers. It is
not, therefore, composed simply of _kaolin_ and _petuntse_. The English
china is generally baked at a much lower heat than that of Sèvres,
Dresden, and Berlin; and it is covered with a mere glass. Being
manufactured upon a prodigious scale, with great economy and certainty,
and little expenditure of fuel, it is sold at a very moderate price
compared with the foreign porcelain, and in external appearance is now
not much inferior.

Some of the English porcelain has been called ironstone china. This is
composed usually of 60 parts of Cornish stone, 40 of china clay, and 2
of flint glass; or of 42 of the felspar, the same quantity of clay, 10
parts of flints ground, and 8 of flint glass.

The glaze for the first composition is made with 20 parts of felspar, 15
of flints, 6 of red lead, and 5 of soda, which are fritted together;
with 44 parts of the frit, 22 parts of flint glass, and 15 parts of
white lead, are ground.

The glaze for the second composition is formed of 8 parts of flint
glass, 36 of felspar, 40 of white lead, and 20 of silex (ground flints).

The English manufacturers employ three sorts of compositions for the
porcelain biscuit; namely, two compositions not fritted; one of them for
the ordinary table service; another for the dessert service and tea
dishes; the third, which is fritted, corresponds to the paste used in
France for sculpture; and with it all delicate kinds of ornaments are
made.

  +--------------+------------+------------+-------------+
  |              |   First    |   Second   |   Third     |
  |              |composition.|composition.|composition. |
  +--------------+------------+------------+-------------+
  |Ground flints |     75     |          66|Lynn sand 150|
  |Calcined bones|    180     |         100|          300|
  |China clay    |     40     |          96|          100|
  |Clay          |     70     |Granite   80|Potash     10|
  +--------------+------------+------------+-------------+

The glaze for the first two of the preceding compositions consists of,
felspar 45, flints 9, borax 21, flint glass 20, nickel 4. After fritting
that mixture, add 12 parts of red lead. For the third composition, which
is the most fusible, the glaze must receive 12 parts of ground flints,
instead of 9; and there should be only 15 parts of borax, instead of 21.

PLAN OF AN ENGLISH POTTERY.

A stoneware manufactory should be placed by the side of a canal or
navigable river, because the articles manufactured do not well bear land
carriage.

A Staffordshire pottery is usually built as a quadrangle, each side
being about 100 feet long, the walls 10 feet high, and the ridge of the
roof 5 feet more. The base of the edifice consists of a bed of bricks,
18 inches high, and 16 inches thick; upon which a mud wall in a wooden
frame, called _pisé_, is raised. Cellars are formed in front of the
buildings, as depôts for the pastes prepared in the establishment. The
wall of the yard or court is 9 feet high, and 18 inches thick.

[Illustration: 899]

_Fig._ 899. A, is the entrance door; B, the porter’s lodge; C, a
particular warehouse; D, workshop of the plaster-moulder; E, the clay
depôt; F, F, large gates, 6 feet 8 inches high; G, the winter
evaporation stove; H, the shop for sifting the paste liquors; I, sheds
for the paste liquor tubs; J, paste liquor pits; K, workshop for the
moulder of hollow ware; L, ditto of the dish or plate moulder; M, the
plate drying-stove; N, workshop of the biscuit-printers; O, ditto of the
biscuit, with _o´_, a long window; P, passage leading to the paste
liquor pits; Q, biscuit warehouse; R, place where the biscuit is cleaned
as it comes out of the biscuit kilns, S S; T, T, enamel or glaze kilns;
U, long passage; V, space left for supplementary workshops; X, space
appointed as a depôt for the sagger fire-clay, as also for making the
saggers; Z, the workshop for applying the glaze liquor to the biscuits;
_a_, apartment for cleaning the glazed ware; _b_, _b_, pumps; _c_,
basin; _d_, muffles; _e_, warehouse for the finished stoneware; _f_,
that of the glazed goods; _g_, _g_, another warehouse; _h_, a large
space for the smith’s forge, carpenter’s shop, packing room, depôt of
clays, saggers, &c. The packing and loading of the goods are performed
in front of the warehouse, which has two outlets, in order to
facilitate the work; _i_, a passage to the court or yard; _l_, a space
for the wooden sheds for keeping hay, clay, and other miscellaneous
articles, _m_, room for putting the biscuit into the saggers; _m´_, a
long window; _n_, workshop with lathes and fly-wheels; _o_, drying-room;
_p_, room for mounting or furnishing the pieces; _q_, repairing room;
_r_, drying room of the goods roughly turned; _s_, rough turning or
blocking-out room; _t_, room for beating the paste or dough; _u_,
counting-house.

The declared value of the earthenware exported in 1836, was 837,774_l._;
in 1837, 558,682_l._

There are from 33,000 to 35,000 tons of clay exported annually from
Poole, in Dorsetshire, to the English and Scotch potteries. A good deal
of clay is also sent from Devonshire and Cornwall.

The Spanish _alcarazzas_, or cooling vessels, are made porous, to favour
the exudation of water through them, and maintain a constantly moist
evaporating surface. Lasteyrie says, that granular sea salt is an
ingredient of the paste of the Spanish alcarazzas; which being expelled
partly by the heat of the baking, and partly by the subsequent watery
percolation, leaves the body very open. The biscuit should be charged
with a considerable proportion of sand, and very moderately fired.

OF PORCELAIN.

Porcelain is a kind of pottery ware whose paste is fine grained,
compact, very hard, and faintly translucid; and whose biscuit softens
slightly in the kiln. Its ordinary whiteness cannot form a definite
character, since there are porcelain pastes variously coloured. There
are two species of porcelain, very different in their nature, the
essential properties of which it is of consequence to establish; the one
is called _hard_, and the other _tender_; important distinctions, the
neglect of which has introduced great confusion into many treatises on
this elegant manufacture.

_Hard_ porcelain is essentially composed, first, of a natural clay
containing some silica, infusible, and preserving its whiteness in a
strong heat; this is almost always a true kaolin; secondly, of a flux,
consisting of silica and lime, composing a quartzose felspar rock,
called _pe-tun-tse_. The glaze of this porcelain, likewise earthy,
admits of no metallic substance or alkali.

_Tender_ porcelain, styled also vitreous porcelain, has no relation with
the preceding in its composition; it always consists of a vitreous frit,
rendered opaque and less fusible by the addition of a calcareous or
marly clay. Its glaze is an artificial glass or crystal, into which
silica, alkalis, and lead enter.

This porcelain has a more vitreous biscuit, more transparent, a little
less hard, and less fragile, but much more fusible than that of the hard
porcelain. Its glaze is more glossy, more transparent, a little less
white, much tenderer, and more fusible.

The biscuit of the hard porcelain made at the French national
manufactory of Sèvres is generally composed of a kaolin clay, and of a
decomposed felspar rock; analogous to the china clay of Cornwall, and
Cornish stone. Both of the above French materials come from Saint
Yriex-la-perche, near Limoges.

After many experiments, the following composition has been adopted for
the _service paste_ of the royal manufactory of Sèvres; that is, for all
the ware which is to be glazed: silica, 59; alumina, 35·2; potash, 2·2;
lime, 3·3. The conditions of such a compound are pretty nearly fulfilled
by taking from 63 to 70 of the washed kaolin or china clay, 22 to 15 of
the felspar; nearly 10 of flint powder, and about 5 of chalk. The glaze
is composed solely of solid felspar, calcined, crushed, and then ground
fine at the mill. This rock pretty uniformly consists of silica 73,
alumina 16·2, potash 8·4, and water 0·6.

The kaolin is washed at the pit, and sent in this state to Sèvres, under
the name of _decanted earth_. At the manufactory it is washed and
elutriated with care; and its slip is passed through fine sieves. This
forms the plastic, infusible, and opaque ingredient to which the
substance must be added which gives it a certain degree of fusibility
and semi-transparency. The felspar rock used for this purpose, should
contain neither dark mica nor iron, either as an oxide or sulphuret. It
is calcined to make it crushable, under stamp-pestles driven by
machinery, then ground fine in hornstone mills, as represented in
_figs._ 897, 898, 899, and 900. This pulverulent matter being diffused
through water, is mixed in certain proportions, regulated by its
quality, with the argillaceous _slip_. The mixture is deprived of the
chief part of its water in shallow plaster pans without heat; and the
resulting paste is set aside to ripen, in damp cellars, for many months.

When wanted for use, it is placed in hemispherical pans of plaster,
which absorb the redundant moisture; after which it is divided into
small lumps, and completely dried. It is next pulverized, moistened a
little, and laid on a floor, and trodden upon by a workman marching over
it with bare feet in every direction; the parings and fragments of soft
moulded articles being intermixed, which improve the plasticity of the
whole. When sufficiently tramped, it is made up into masses of the size
of a man’s head, and kept damp till required.

The dough is now in a state fit for the potter’s lathe; but it is much
less plastic than stoneware paste, and is more difficult to fashion into
the various articles; and hence one cause of the higher price of
porcelain.

The round plates and dishes are shaped on plaster moulds; but sometimes
the paste is laid on as a crust, and at others it is turned into shape
on the lathe. When a crust is to be made, a moistened sheep-skin is
spread on a marble table; and over this the dough is extended with a
rolling pin, supported on two guide-rules. The crust is then transferred
over the plaster mould, by lifting it upon the skin; for it wants
tenacity to bear raising by itself. When the piece is to be fashioned on
the lathe, a lump of the dough is thrown on the centre of the horizontal
wooden disc, and turned into form as directed in treating of stoneware,
only it must be left much thicker than in its finished state. After it
dries to a certain degree on the plaster mould, the workman replaces it
on the lathe, by moistening it on its base with a wet sponge, and
finishes its form with an iron tool. A good workman at Sèvres makes no
more than from 15 to 20 porcelain plates in a day; whereas an English
potter, with two boys, makes from 1000 to 1200 plates of stoneware in
the same time. The pieces which are not round, are shaped in plaster
moulds, and finished by hand. When the articles are very large, as
wash-hand basins, salads, &c., a flat cake is spread above a skin on the
marble slab, which is then applied to the mould with the sponge, as for
plates; and they are finished by hand.

The projecting pieces, such as handles, beaks, spouts, and ornaments,
are moulded and adjusted separately; and are cemented to the bodies of
china-ware with slip, or porcelain dough thinned with water. In fact,
the mechanical processes with porcelain and the finer stoneware are
substantially the same; only they require more time and greater nicety.
The least defect in the fabrication, the smallest bit added, an unequal
pressure, the cracks of the moulds, although well repaired, and
seemingly effaced in the clay shape, re-appear after it is baked. The
articles should be allowed to dry very slowly; if hurried but a little,
they are liable to be spoiled. When quite dry, they are taken to the
kiln.

The kiln for hard porcelain at Sèvres, is a kind of tower in two flats,
constructed of fire-bricks; and resembles, in other respects, the
stoneware kiln already figured and described. The fuel is young aspin
wood, very dry, and cleft very small; it is put into the apertures of
the four outside furnaces or fire-mouths, which discharge their flame
into the inside of the kiln; each floor being closed in above, by a dome
pierced with holes. The whole is covered in by a roof with an open
passage, placed at a proper distance from the uppermost dome. There is,
therefore, no chimney proper so called. See STONE, ARTIFICIAL.

The raw pieces are put into the upper floor of the kiln; where they
receive a heat of about the 60th degree of Wedgewood’s pyrometer, and a
commencement of baking, which, without altering their shape, or causing
a perceptible shrinking of their bulk, makes them completely dry, and
gives them sufficient solidity to bear handling. By this preliminary
baking, the clay loses its property of forming a paste with water; and
the pieces become fit for receiving the glazing coat, as they may be
dipped in water without risk of breakage.

The glaze of hard porcelain is a felspar rock: this being ground to a
very fine powder, is worked into a paste with water mingled with a
little vinegar. All the articles are dipped into this milky liquid for
an instant; and as they are very porous, they absorb the water greedily,
whereby a layer of the felspar glaze is deposited on their surface, in a
nearly dry state, as soon as they are lifted out. Glaze-pap is
afterwards applied with a hair brush to the projecting edges, or any
points where it had not taken; and the powder is then removed from the
part on which the article is to stand, lest it should get fixed to its
support in the fire. After these operations it is replaced in the kiln,
to be completely baked.

The articles are put into saggers, like those of fine stoneware; and
this operation is one of the most delicate and expensive in the
manufacture of porcelain. The saggers are made of the plastic or
potter’s clay of Abondant, to which about a third part of cement of
broken saggers has been added.

As the porcelain pieces soften somewhat in the fire, they cannot be set
above each other, even were they free from glaze; for the same reason,
they cannot be baked on tripods, several of them being in one case, as
is done with stoneware. Every piece of porcelain requires a sagger for
itself. They must, moreover, be placed on a perfectly flat surface,
because in softening they would be apt to conform to the irregularities
of a rough one. When therefore any piece, a soup plate for example, is
to be _saggered_, there is laid on the bottom of the case a perfectly
true disc or round cake of stoneware, made of the sagger material, and
it is secured in its place on three small props of a clay-lute,
consisting of potter’s clay mixed with a great deal of sand. When the
cake is carefully levelled, it is moistened, and dusted over with sand,
or coated with a film of fire-clay slip, and the porcelain is carefully
set on it. The sand or fire-clay hinders it from sticking to the cake.
Several small articles may be set on the same cake, provided they do not
touch one another.

The saggers containing the pieces thus arranged, are piled up in the
kiln over each other, in the columnar form, till the whole space be
occupied; leaving very moderate intervals between the columns to favour
the draught of the fires. The whole being arranged with these
precautions, and several others, too minute to be specified here, the
door of the kiln is built up with 3 rows of bricks, leaving merely an
opening 8 inches square, through which there is access to a sagger with
the nearest side cut off. In this sagger are put fragments of porcelain
intended to be withdrawn from time to time, in order to judge of the
progress of the baking. These are called time-pieces or watches
(_montres_). This opening into the watches is closed by a stopper of
stoneware.

The firing begins by throwing into the furnace-mouths some pretty large
pieces of white wood, and the heat is maintained for about 15 hours,
gradually raising it by the addition of a larger quantity of the wood,
till at the end of that period the kiln has a cherry-red colour within.
The heat is now greatly increased by the operation termed _covering the
fire_. Instead of throwing billets vertically into the four furnaces,
there is placed horizontally on the openings of these furnaces, aspin
wood of a sound texture, cleft small, laid in a sloping position. The
brisk and long flame which it yields dips into the tunnels, penetrates
the kiln, and circulates round the sagger-piles. The heat augments
rapidly, and, at the end of 13 or 15 hours of this firing, the interior
of the kiln is so white, that the watches can hardly be distinguished.
The draught, indeed, is so rapid at this time, that one may place his
hand on the slope of the wood without feeling incommoded by the heat.
Every thing is consumed, no small charcoal remains, smoke is no longer
produced, and even the wood-ash is dissipated. It is obvious that the
kiln and the saggers must be composed of a very refractory clay, in
order to resist such a fire. The heat in the Sèvres kilns mounts so high
as the 134th degree of Wedgewood.

At the end of 15 or 20 hours of the great fire; that is, after from 30
to 36 hours’ firing, the porcelain is baked; as is ascertained by taking
out and examining the watches. The kiln is suffered to cool during 3 or
4 days, and is then opened and discharged. The sand strewed on the cakes
to prevent the adhesion of the articles to them, gets attached to their
sole, and is removed by friction with a hard sandstone; an operation
which one woman can perform for a whole kiln in less than 10 days; and
is the last applied to hard porcelain, unless it needs to be returned
into the hot kiln to have some defects repaired.

The materials of fine porcelain are very rare; and there would be no
advantage in making a gray-white porcelain with coarser and somewhat
cheaper materials, for the other sources of expense above detailed, and
which are of most consequence, would still exist; while the porcelain,
losing much of its brightness, would lose the main part of its value.

Its pap or dough, which requires tedious grinding and manipulation, is
also more difficult to work into shapes, in the ratio of 80 to 1,
compared to fine stoneware. Each porcelain plate requires a separate
sagger; so that 12 occupy in the kiln a space sufficient for at least 38
stoneware plates. The temperature of a hard porcelain kiln being very
high, involves a proportionate consumption of fuel and waste of saggers.
With 40 _steres_ (cubic metres) of wood, 12,000 stoneware plates may be
completely fired, both in the biscuit and glaze kilns; while the same
quantity of wood would bake at most only 1000 plates of porcelain.

To these causes of high price, which are constant and essential, we
ought to add the numerous accidents to which porcelain is exposed at
every step of its preparation, and particularly in the kiln; these
accidents damage upwards of one-third of the pieces, and frequently
more, when articles of singular form and large dimensions are
adventured.

The best English porcelain is made from a mixture of the Cornish kaolin
(called china clay), ground flints, ground Cornish stone, and calcined
bones in powder, or bone-ash, besides some other materials, according to
the fancy of the manufacturers. A liquid pap is made with these
materials, compounded in certain proportions, and diluted with water.
The fluid part is then withdrawn by the absorbent action of dry stucco
basins or pans. The dough, brought to a proper stiffness, and perfectly
worked and kneaded on the principles detailed above, is fashioned on the
lathe, by the hands of modellers, or by pressure in moulds. The pieces
are then baked to the state of biscuit in a kiln, being enclosed, of
course, in saggers.

This biscuit has the aspect of white sugar, and being very porous, must
receive a vitreous coating. The glaze consists of ground felspar or
Cornish stone. Into this, diffused in water, along with a little
flint-powder and potash, the biscuit ware is dipped, as already
described, under stoneware. The pieces are then fired in the glaze-kiln,
care being taken, before putting them into their saggers, to remove the
glaze powder from their bottom parts, to prevent their adhesion to the
fire-clay vessel.

TENDER PORCELAIN.

Tender porcelain, or soft china-ware, is made with a vitreous frit,
rendered less fusible and opaque by an addition of white marl or
bone-ash. The frit is, therefore, first prepared. This, at Sèvres, is a
composition, made with some nitre, a little sea salt, Alicant barilla,
alum, gypsum, and much siliceous sand or ground flints. That mixture is
subjected to an incipient pasty fusion in a furnace, where it is stirred
about to blend the materials well; and thus a very white spongy frit is
obtained. It is pulverized, and to every three parts of it, one of the
white marl of Argenteuil is added; and when the whole are well ground,
and intimately mixed, the paste of tender porcelain is formed.

As this paste has no tenacity, it cannot bear working till a mucilage of
gum or black soap be added, which gives it a kind of plasticity, though
even then it will not bear the lathe. Hence it must be fashioned in the
press, between two moulds of plaster. The pieces are left thicker than
they should be; and when dried, are finished on the lathe with iron
tools.

In this state they are baked, without any glaze being applied; but as
this porcelain softens far more during the baking than the hard
porcelain, it needs to be supported on every side. This is done by
baking on earthen moulds all such pieces as can be treated in this way,
namely plates, saucers, &c. The pieces are reversed on these moulds, and
undergo their shrinkage without losing their form. Beneath other
articles, supports of a like paste are laid, which suffer in baking the
same contraction as the articles, and of course can serve only once. In
this operation saggers are used, in which the pieces and their supports
are fired.

The kiln for the tender porcelain at Sèvres is absolutely similar to
that for the common stoneware; but it has two floors; and while the
biscuit is baked in the lower story, the glaze is fused in the upper
one; which causes considerable economy of fuel. The glaze of soft
porcelain is a species of glass or crystal prepared on purpose. It is
composed of flint, siliceous sand, a little potash or soda, and about
two-fifth parts of lead oxide. This mixture is melted in crucibles or
pots beneath the kiln. The resulting glass is ground fine, and diffused
through water mixed with a little vinegar to the consistence of cream.
All the pieces of biscuit are covered with this glazy matter, by pouring
this slip over them, since their substance is not absorbent enough to
take it on by immersion.

The pieces are encased once more each in a separate sagger, but without
any supports; for the heat of the upper floor of the kiln, though
adequate to melt the glaze, is not strong enough to soften the biscuit.
But as this first vitreous coat is not very equal, a second one is
applied, and the pieces are returned to the kiln for the third time. See
STONE, ARTIFICIAL, for a view of this kiln.

The manufacture of soft porcelain is longer and more difficult than that
of hard; its biscuit is dearer, although the raw materials may be found
every where; and it furnishes also more refuse. Many of the pieces split
asunder, receive fissures, or become deformed in the biscuit-kiln, in
spite of the supports; and this vitreous porcelain, moreover, is always
yellower, more transparent, and incapable of bearing rapid transitions
of temperature, so that even the heat of boiling water frequently cracks
it. It possesses some advantages as to painting, and may be made so
gaudy and brilliant in its decorations, as to captivate the vulgar eye.

DESCRIPTION OF THE PORCELAIN MILL.

[Illustration: 900]

1. The following figures of a felspar and flint mill are taken from
plans of apparatus lately constructed by Mr. Hall of Dartford, and
erected by him in the royal manufactory of Sèvres. There are two similar
sets of apparatus, _fig._ 900., which may be employed together or in
succession; composed each of an elevated tub A, and of three successive
vats of reception A´, and two behind it, whose top edges are upon a
lower level than the bottom of the casks A, A, to allow of the liquid
running out of them with a sufficient slope. A proper charge of kaolin
is first put into the cask A, then water is gradually run into it by the
gutter adapted to the stopcock _a_, after which the mixture is agitated
powerfully in every direction by hand with the stirring-bar, which is
hung within a hole in the ceiling, and has at its upper end a small
tin-plate funnel to prevent dirt or rust from dropping down into the
clay. The stirrer may be raised or lowered so as to touch any part of
the cask. The semi-fluid mass is left to settle for a few minutes, and
then the finer argillaceous pap is run off by the stopcock _a´_, placed
a little above the gritty deposit, into the zinc pipe which conveys it
into one of the tubs A´; but as this semi-liquid matter may still
contain some granular substances, it must be passed through a sieve
before it is admitted into the tub. There is, therefore, at the spot
upon the tub where the zinc pipe terminates, a wire-cloth sieve, of an
extremely close texture, to receive the liquid paste. This sieve is
shaken upon its support, in order to make it discharge the washed
argillaceous kaolin. After the clay has subsided, the water is drawn off
from its surface by a zinc syphon. The vats A´ have covers, to protect
their contents from dust. In the pottery factories of England, the
agitation is produced by machinery, instead of the hand. A vertical
shaft, with horizontal or oblique paddles, is made to revolve in the
vats for this purpose.

[Illustration: 901]

_The small triturating mill_ is represented in _fig._ 901. There are
three similar grinding-tubs on the same line. The details of the
construction are shown in _figs._ 902, 903, where it is seen to consist
principally of a revolving millstone B (_fig._ 902.), of a fast or
sleeper millstone B´, and of a vat C, hooped with iron, with its top
raised above the upper millstone. The lower block of hornstone rests
upon a very firm basis, _b´_; it is surrounded immediately by the strong
wooden circle _c_, which slopes out funnel-wise above, in order to throw
back the earthy matters as they are pushed up by the attrition of the
stones. That piece is hollowed out, partially to admit the key C,
opposite to which is the faucet and spigot _c´_, for emptying the tub.
When one operation is completed, the key C is lifted out by means of a
peg put into the holes at its top; the spigot is then drawn, and the
thin paste is run out into vats. The upper grindstone, B _d_, like the
lower one, is about two feet in diameter, and must be cut in a peculiar
manner. At first there is scooped out a hollowing in the form of a
sector, denoted by _d e f_, _fig._ 903.; the arc _d f_ is about
one-sixth of the circumference, so that the vacuity of the turning
grindstone is one-sixth of its surface; moreover, the stone must be
channelled, in order to grind or crush the hard gritty substances. For
this purpose, a wedge-shaped groove _d e g_, about an inch and a quarter
deep, is made on its under face, whereby the stone, as it turns in the
direction indicated by the arrow, acts with this inclined plane upon all
the particles in its course, crushing them and forcing them in between
the stones, till they be triturated to an impalpable powder. When the
grindstone wears unequally on its lower surface, it is useful to trace
upon it little furrows, proceeding from the centre to the circumference,
like those shown by the dotted lines _e´ e´´_. It must, moreover, be
indented with rough points by the hammer.

[Illustration: 902 903]

The turning hornstone-block is set in motion by the vertical shaft H,
which is fixed by the clamp-iron cross I to the top of the stone. When
the stone is new, its thickness is about 14 inches, and it is made to
answer for grinding till it be reduced to about 8 inches, by lowering
the clamp I upon the shaft, so that it may continue to keep its hold of
the stone. The manner in which the grindstones are turned, is obvious
from inspection of _fig._ 901., where the horizontal axis L, which
receives its impulsion from the great water-wheel, turns the prolonged
shaft L´, or leaves it at rest, according as the clutch _l_, _l´_, is
locked or opened. This second shaft bears the three bevel wheels M, M,
M. These work in three corresponding bevel wheels M´ M´ M´, made fast
respectively to the three vertical shafts of the millstones, which pass
through the cast-iron guide tubes M´´ M´´. These are fixed in a truly
vertical position by the collar-bar _m´´_, _m´_, _fig._ 902. In this
figure we see at _m_ how the strong cross-bar of cast iron is made fast
to the wooden beams which support all the upper mechanism of the
mill-work. The bearing _m´_ is disposed in an analogous manner; but it
is supported against two cast-iron columns, shown at L´´ L´´, in _fig._
901. The guide tubes M´´ are bored smooth for a small distance from each
of their extremities, and their interjacent calibre is wider, so that
the vertical shafts touch only at two places. It is obvious, that
whenever the shaft L´ is set a-going, it necessarily turns the wheels M
and M´, and their guide tubes M´´; but the vertical shaft may remain
either at rest, or revolve, according to the position of the lever click
or catch K, at the top, which is made to slide upon the shaft, and can
let fall a finger into a vertical groove cut in the surface of that
shaft. The clamp-fork of the click is thus made to catch upon the
horizontal bevel-wheel M´, or to release it, according as the lever K is
lowered or lifted up. Thus each millstone may be thrown out of or into
geer at pleasure.

[Illustrations: 904 905 906 907]

These stones make upon an average 11 or 12 turns in a minute,
corresponding to 3 revolutions of the water-wheel, which moves through a
space of 3 feet 4 inches in the second, its outer circumference being 66
feet. The weight of the upper stone, with its iron mountings, is about 6
cwt., when new. The charge of each mill in dry material is 2 cwt.; and
the water may be estimated at from one-half to the whole of this weight;
whence the total load may be reckoned to be at least 3 cwt.; the stone,
by displacement of the magma, loses fully 400 pounds of its weight, and
weighs therefore in reality only 2 cwt. It is charged in successive
portions, but it is discharged all at once. When the grinding of the
siliceous or felspar matters is nearly complete, a remarkable
phenomenon occurs; the substance precipitates to the bottom, and assumes
in a few seconds so strong a degree of cohesion, that it is hardly
possible to restore it again to the pasty or magma state; hence if a
millstone turns too slowly, or if it be accidentally stopped for a few
minutes, the upper stone gets so firmly cemented to the under one, that
it is difficult to separate them. It has been discovered, but without
knowing why, that a little vinegar added to the water of the magma
almost infallibly prevents that sudden stiffening of the deposit and
stoppage of the stones. If the mills come to be set fast in this way,
the shafts or geering would be certainly broken, were not some safety
provision to be made in the machinery against such accidents. Mr. Hall’s
contrivance to obviate the above danger is highly ingenious. The clutch
_l_, _l´_, _fig._ 901., is not a locking crab, fixed in the common way,
upon the shaft L; but it is composed, as shown in _figs._ 904, 905, 906,
907, of a hoop _u_, fixed upon the shaft by means of a key, of a collar
_v_, and of a flat ring or washer _x_, with four projections, which are
fitted to the collar _v_, by four bolts _y_. _Fig._ 905. represents the
collar _v_ seen in front; that is, by the face which carries the clutch
teeth; and _fig._ 906. represents its other face, which receives the
flat ring _x_, _fig._ 907., in four notches corresponding to the four
projections of the washer-ring. Since the ring _u_ is fixed upon the
shaft L, and necessarily turns with it, it has the two other pieces at
its disposal, namely the collar _v_, and the washer _x_, because they
are always connected with it by the four bolts _y_, so as to turn with
the ring _u_, when the resistance they encounter upon the shaft L´ is
not too great, and to remain at rest, letting the ring _u_ turn by
itself, when that resistance increases to a certain pitch. To give this
degree of friction, we need only interpose the leather washers _z_,
_z´_, _fig._ 904.; and now as the collar _coupling-box_, _v_, slides
pretty freely upon the ring _u_, it is obvious that by tightening more
or less the screw bolts _y_, these washers will become as it were a
lateral brake, to tighten more or less the bearing of the ring _u_, to
which they are applied: by regulating this pressure, every thing may be
easily adjusted. When the resistance becomes too great, the leather
washers, pressed upon one side by the collar _v_, of the washer _x_, and
rubbed upon the other side by the prominence of the ring _u_, get heated
to such a degree, that they are apt to become carbonized, and require
replacement.

This safety clutch may be recommended to the notice of mechanicians, as
susceptible of beneficial application in a variety of circumstances.

GREAT PORCELAIN MILL.

The large felspar and kaolin mill, made by Mr. Hall, for Sèvres, has a
flat bed of hornstone, in one block, laid at the bottom of a great tub,
hooped strongly with iron. In most of the English potteries, however,
that bed consists of several flat pieces of chert or hornstone, laid
level with each other. There is, as usual, a spigot and faucet at the
side, for drawing off the liquid paste. The whole system of the
mechanism is very substantial, and is supported by wooden beams.

The following is the manner of turning the upper blocks. In _fig._ 900.
the main horizontal shaft P bears at one of its extremities a toothed
wheel, usually mounted upon the periphery of the great water-wheel
(_fig._ 908. shows this toothed wheel by a dotted line) at its other
end; P carries the fixed portion _p_ of a coupling-box, similar to the
one just described as belonging to the little mill. On the prolongation
of P, there is a second shaft P´, which bears the movable portion of
that box, and an upright bevel wheel P´´. Lastly, in _figs._ 900. and
908. there is shown the vertical shaft Q, which carries at its upper end
a large horizontal cast-iron wheel Q´, not seen in this view, because it
is sunk within the upper surface of the turning hornstone, like the
clamp _d_, _f_, in _fig._ 902. At the lower end of the shaft Q, there is
the bevel wheel Q´´, which receives motion from the wheel P´´, _fig._
900.

The shaft P always revolves with the water-wheel; but transmits its
motion to the shaft P´ only when the latter is thrown into geer with
the coupling-box _p´_, by means of its forked lever. Then the bevel
wheel P´ turns round with the shaft P´, and communicates its rotation to
the bevel wheel Q´´, which transmits it to the shaft Q, and to the large
cast-iron wheel, which is sunk into the upper surface of the revolving
hornstone.

[Illustration: 908]

The shaft Q is supported and centred by a simple and solid adjustment;
at its lower part, it rests in a step R, which is supported upon a
cast-iron arch Q´, seen in profile in _fig._ 900.; its base is solidly
fixed by four strong bolts. Four set screws above R, _fig._ 900., serve
to set the shaft Q truly perpendicular: thus supported, and held
securely at its lower end, in the step at R, _figs._ 900. and 908., it
is embraced near the upper end by a brass bush or collar, composed of
two pieces, which may be drawn closer together by means of a screw. This
collar is set into the summit of a great truncated cone of cast-iron,
which rises within the tub through two-thirds of the thickness of the
hornstone bed; having its base firmly fixed by bolts to the bottom of
the tub, and having a brass collet to secure its top. The iron cone is
cased in wood. When all these pieces are well adjusted and properly
screwed up, the shaft Q revolves without the least vacillation, and
carries round with it the large iron wheel Q´, cast in one piece, and
which consists of an outer rim, three arms or radii, and a strong
central nave, made fast by a key to the top of the shaft Q, and resting
upon a shoulder nicely turned to receive it. Upon each of the three
arms, there are adjusted, with bolts, three upright substantial bars of
oak, which descend vertically through the body of the revolving mill to
within a small distance of the bed-stone; and upon each of the three
arcs of that wheel-ring, comprised between its three strong arms, there
are adjusted, in like manner, five similar uprights, which fit into
hollows cut in the periphery of the moving stone. They ought to be cut
to a level at their lower part, to suit the slope of the bottom of the
tub _o_, _figs._ 900. and 908., so as to glide past it pretty closely,
without touching.

The speed of this large mill is eight revolutions in the minute. The
turning hornstone describes a mean circumference of 141-1/3 inches (its
diameter being 45 inches), and of course moves through about 100 feet
per second. The tub O, is 52 inches wide at bottom, 56 at the surface of
the sleeper block (which is 16 inches thick), and 64 at top, inside
measure. It sometimes happens that the millstone throws the pasty
mixture out of the vessel, though its top is 6 inches under the lip of
the tub _o_; an inconvenience which can be obviated only by making the
pap a little thicker; that, is by allowing only from 25 to 30 per cent.
of water; then its density becomes nearly equal to 2·00, while that of
the millstones themselves is only 2·7; whence, supposing them to weigh
only 2 cwt., there would remain an effective weight of less than 1/2
cwt. for pressing upon the bottom and grinding the granular particles.
This weight appears to be somewhat too small to do much work in a short
time; and therefore it would be better to increase the quantity of
water, and put covers of some convenient form over the tubs. It is
estimated that this mill will grind nearly 5 cwt. of hard kaolin or
felspar gravel, in 24 hours, into a proper pap.

To the preceding methodical account of the porcelain manufacture, I
shall now subjoin some practical details relative to certain styles of
work, with comparisons between the methods pursued in this country and
upon the Continent, but chiefly by our jealous rivals the French.

The blue printed ware of England has been hitherto a hopeless object of
emulation in France. M. Alexandre Brongniart, membre de l’Institut, and
director of the _Manufacture Royal de Sèvres_, characterizes the French
imitations of the _Fayence fine, ou Anglaise_, in the following terms:
“Les défauts de cette poterie, qui tiennent à sa nature, sont de ne
pouvoir aller sur le feu pour les usages domestiques, et d’avoir un
vernis tendre, qui se laisse aisément entamer par les instruments
d’acier et de fer. Mais lorsque cette poterie est mal fabriquée, ou
fabriquée avec une économie mal entendue, ses défauts deviennent bien
plus graves; son vernis jaunâtre et tendre tressaille souvent; il se
laisse entamer ou user avec la plus grande facilité par les instruments
de fer, ou par l’usage ordinaire. Les fissures que ce tressaillement ou
ces rayures ouvrent dans le vernis permettent aux matières grasses de
pénétrer dans le biscuit, que dans les poteries affectées de ce défaut,
a presque toujours une texture lâche; les pièces se salissent,
s’empuantissent, et se brisent même avec la plus grande facilité.”[42]

  [42] Dict. Technologique, tom. xvii., article Poteries, p. 253.

What a glaze, to be scratched or grooved with soft iron; to fly off in
scales, so as to let grease soak into the biscuit or body of the ware;
to become foul, stink, and break with the utmost ease! The refuse
crockery of the coarsest pottery works in the United Kingdom would
hardly deserve such censure.

In the minutes of evidence of the _Enquête Ministérielle_, published in
1835, MM. de Saint Cricq and Lebeuf, large manufacturers of pottery-ware
at Creil and Montereau, give a very gratifying account of the English
stoneware manufacture. They declare that the English possess magnificent
mines of potter’s clay, many leagues in extent; while those of the
French are mere patches or _pots_. Besides, England, they say, having
upwards of 200 potteries, can constantly employ a great many public
flint-mills, and thereby obtain that indispensable material of the best
quality, and at the lowest rate. “The mill erected by M. Brongniart, at
Sèvres, does its work at twice the price of the English mills. The fuel
costs in England one-fourth of what it does in France. The expense of a
kiln-round, in the latter country, is 200 francs; while in the former it
is not more than 60.” After a two-months tour among the English
potteries, these gentlemen made the following additional observations to
their first official statement:----

“The clay, which goes by water carriage from the counties of Devon and
Dorset, into Staffordshire, to supply more than 200 potteries, clustered
together, is delivered to them at a cost of 4 francs (3_s._ 2_d._) the
100 kilogrammes (2 cwt.); at Creil, it costs 4_f._ 50_c._, and at
Montereau, only 2_f._ 40_c._ There appears, therefore, to be no
essential difference in the price of the clay; but the quality of the
English is much superior, being incontestably whiter, purer, more
homogeneous, and not turning red at a high heat, like the French.” The
grinding of the flints costs the English potter 4-1/2_d._ per 100
kilos., and the French 6_d._; but as that of the latter is in general
ground dry, it is a coarser article. The kaolin, or china clay, is
imported from Cornwall for the use of many French potteries; but the
transport of merchandise is so ill managed in France, that while 2 cwts.
cost in Staffordshire only 8_f._ 75_c._ (about 7_s._ 1_d._), they cost
12_f._ at Creil, and 13f. 50_c._ at Montereau. The white lead and
massicot, so much employed for glazes, are 62 per cent. dearer to the
French potters than the English. As no French mill has succeeded in
making unsized paper fit for printing upon stoneware, our potters are
under the necessity of fetching it from England; and, under favour of
our own custom-house, are allowed to import it at a duty of 165_f._ per
100 kilogrammes, or about 8_d._ per pound English. No large stock of
materials need be kept by the English, because every article may be had
when wanted from its appropriate wholesale dealers; but the case is
quite different with the French, whose stocks, even in small works, can
never safely be less in value than 150,000_f._ or 200,000_f._;
constituting a loss to them, in interest upon their capital, of from
7,500_f._ to 10,000_f._ per annum. The capital sunk in buildings is far
less in England than in France, in consequence of the different styles
of erecting stoneware factories in the two countries. M. de Saint Cricq
informs us, that Mr. Clewes, of Shelton, rents his works for 10,000_f._
(380_l._) per annum; while the similar ones of Creil and Montereau, in
France, have cost each a capital outlay of from 500,000_f._ to
600,000_f._, and in which the products are not more than one half of Mr.
Clewes’. “This forms a balance against us,” says M. St. C., “of about
20,000_f._ per annum; or nearly 800_l._ sterling. Finally, we have the
most formidable rival to our potteries in the extreme dexterity of the
English artisans. An enormous fabrication permits the manufacturers to
employ the same workmen during the whole year upon the same piece; thus
I have seen at Shelton a furnisher, for sixpence, turn off 100 pieces,
which cost at Creil and Montereau 30 sous (1_s._ 2-1/2_d._); yet the
English workman earns 18_f._ 75_c._ a week, while the French never earns
more than 15_f._ I have likewise seen an English moulder expert enough
to make 25 waterpots a day, which, at the rate of 2_d._ a piece, bring
him 4_s._ 2_d._ of daily wages; while the French moulder, at daily wages
also of 4_s._ 2_d._, turns out of his hands only 7, or at most 8 pots.
In regard to hollow wares, the English may be fairly allowed to have an
advantage over us, in the cost of labour, of 100 per cent.; which they
derive from the circumstance, that there are in Staffordshire 60,000
operatives, men, women, and children, entirely dedicated to the
stoneware manufacture; concentrating all their energies within a space
of 10 square leagues. Hence a most auspicious choice of good practical
potters, which cannot be found in France.”

M. Saint Amans, a French gentleman, who spent some years in
Staffordshire, and has lately erected a large pottery in France, says
the English surpass all other nations in manufacturing a peculiar
stoneware, remarkable for its lightness, strength, and elegance; as also
in printing blue figures upon it of every tint, equal to that of the
Chinese, by processes of singular facility and promptitude. After the
biscuit is taken out of the kiln, the fresh impression of the engraving
is transferred to it from thin unsized paper, previously immersed in
strong soap water; the ink for this purpose being a compound of
arseniate of cobalt with a flux, ground up with properly boiled linseed
oil. The copper-plates are formed by the graving tool with deeper or
shallower lines according to the variable depth of shades in the design.
The cobalt pigment, on melting, spreads so as to give the soft effect of
water-colour drawing. The paper being still moist, is readily applied to
the slightly rough and adhesive surface of the biscuit, and may be
rubbed on more closely by a dossil of flannel. The piece is then dipped
in a tub of water, whereby the paper gets soft, and may be easily
removed, leaving upon the pottery the pigment of the engraved
impression. After being gently dried, the piece is dipped into the glaze
mixture, and put into the enamel oven.

_Composition of the Earthy Mixtures._

The basis of the English stoneware is, as formerly stated, a bluish
clay, brought from Dorsetshire and Devonshire, which lies at the depth
of from 25 to 30 feet beneath the surface. It is composed of about 24
parts of alumina, and 76 of silica, with some other ingredients in very
small proportions. This clay is very refractory in high heats, a
property which, joined to its whiteness when burned, renders it
peculiarly valuable for pottery. It is also the basis of all the yellow
biscuit-ware called _cream colour_, and in general of what is called the
_printing body_; as also for the semi-vitrified porcelain of Wedgewood’s
invention, and of the tender porcelain.

The constituents of the stoneware are, that clay, the powder of calcined
flints, and of the decomposed felspar called Cornish stone. The
proportions are varied by the different manufacturers. The following are
those generally adopted in one of the principal establishments of
Staffordshire:--

  For _cream colour_, Silex or ground flints  20 parts.
                      Clay                   100
                      Cornish stone            2

_Composition of the Paste for receiving the Printing Body under the
Glaze._

For this purpose the proportions of the flint and the felspar must be
increased. The substances are mixed separately with water into the
consistence of a thick cream, which weighs per pint, for the flints 32
ounces, and for the Cornish stone 28. The china clay of Cornwall is
added to the same mixture of flint and felspar, when a finer pottery or
porcelain is required. That clay cream weighs 24 ounces per pint. These
24 ounces in weight are reduced to one-third of their bulk by
evaporation. The pint of dry Cornish clay weighs 17 ounces, and in its
first pasty state 24, as just stated. The dry flint powder weighs 14-1/2
ounces per pint; which when made into a cream weighs 32 ounces. To 40
measures of Devonshire clay-cream there are added,

  13 measures of flint liquor.
  12    --       Cornish clay ditto.
   1    --       Cornish stone ditto.

The whole are well mixed by proper agitation, half dried in the
_troughs_ of the slip-kiln, and then subjected to the machine for
cutting up the clay into junks. The above paste, when baked, is very
white, hard, sonorous, and susceptible of receiving all sorts of
impressions from the paper engravings. When the silica is mixed with the
alumina in the above proportions, it forms a compact ware, and the
impression remains fixed between the biscuit and the glaze, without
communicating to either any portion of the tint of the metallic colour
employed in the engraver’s press. The felspar gives strength to the
biscuit, and renders it sonorous after being baked; while the china clay
has the double advantage of imparting an agreeable whiteness and great
closeness of grain.


PRECIPITATE, is any matter separated in minute particles from the bosom
of a fluid, which subsides to the bottom of the vessel in a pulverulent
form.


PRECIPITATION, is the actual subsidence of a precipitate.


PRESS, HYDRAULIC. Though the explanation of the principles of this
powerful machine belongs to a work upon mechanical engineering, rather
than to one upon manufactures, yet as it is often referred to in this
volume, a brief description of it cannot be unacceptable to many of my
readers.

[Illustration: 909]

The framing consists of two stout cast-iron plates _a_, _b_, which are
strengthened by projecting ribs, not seen in the section, _fig._ 909.
The top or crown plate _b_, and the base-plate _a_, _a_, are bound most
firmly together by 4 cylinders of the best wrought iron, _c_, _c_, which
pass up through holes near the ends of the said plates, and are fast
wedged in them. The flat pieces _e_, _e_, are screwed to the ends of the
crown and base plates, so as to bind the columns laterally. _f_, is the
hollow cylinder of the press, which, as well as the ram _g_, is made of
cast iron. The upper part of the cavity of the cylinder is cast narrow,
but is truly and smoothly rounded at the boring-mill, so as to fit
pretty closely round a well-turned ram or piston; the under part of it
is left somewhat wider in the casting. A stout cup of leather,
perforated in the middle, is put upon the ram, and serves as a valve to
render the neck of the cylinder perfectly water-tight, by filling up the
space between it and the ram; and since the mouth of the cup is turned
downwards, the greater the pressure of water upwards, the more forcibly
are the edges of the leather valve pressed against the inside of the
cylinder, and the tighter does the joint become. This was Bramah’s
beautiful invention.

Upon the top of the ram, the press-plate or table, strengthened with
projecting ridges, rests, which is commonly called the follower, because
it follows the ram closely in its descent. This plate has a half-round
hole at each of its four corners, corresponding to the shape of the four
iron columns along which it glides in its up-and-down motions of
compression and relaxation.

[Illustration: 910 911 912]

_k_, _k_, _figs._ 909. and 910., is the framing of a force pump with a
narrow barrel; _i_ is the well for containing water to supply the pump.
To spare room in the engraving, the pump is set close to the press, but
it may be removed to any convenient distance by lengthening the
water-pipe _u_, which connects the discharge of the force pump with the
inside of the cylinder of the press. _Fig._ 911. is a section of the
pump and its valves. The pump _m_, is of bronze; the suction-pipe _n_,
has a conical valve with a long tail; the solid piston or plunger _p_,
is smaller than the barrel in which it plays, and passes at its top
through a stuffing-box _q_; _r_ is the pressure-valve, _s_ is the
safety-valve, which, in _fig._ 910., is seen to be loaded with a
weighted lever; _t_ is the discharge-valve, for letting the water
escape, from the cylinder beneath the ram, back into the well. See the
winding passages in _fig._ 912. _u_ is the tube which conveys the water
from the pump into the press-cylinder. In _fig._ 910. two centres of
motion for the pump-lever are shown. By shifting the bolt into the
centre nearest the pump-rod, the mechanical advantage of the workman may
be doubled. Two pumps are generally mounted in one frame for one
hydraulic press; the larger to give a rapid motion to the ram at the
beginning, when the resistance is small; the smaller to give a slower
but more powerful impulsion, when the resistance is much increased. A
pressure of 500 tons may be obtained from a well-made hydraulic press
with a ten-inch ram, and a two and a one inch set of pumps. See STEARINE
PRESS.


PRINCE’S METAL, or Prince Rupert’s metal, is a modification of brass.


PRINTING INK. (_Encre d’imprimerie_, Fr.; _Buchdruckerfarbe_, Germ.)
After reviewing the different prescriptions given by Moxon, Breton,
Papillon, Lewis, those in Nicholson’s and the Messrs. Aikins’
Dictionaries, in Rees’ Cyclopædia, and in the French Printer’s Manual,
Mr. Savage[43] says, that the Encyclopædia Britannica is the only work,
to his knowledge, which has given a recipe by which a printing ink might
be made, that could be used, though it would be of inferior quality, as
acknowledged by the editor; for it specifies neither the qualities of
the materials, nor their due proportions. The fine black ink made by Mr.
Savage, has, he informs us, been pronounced by some of our first
printers to be unrivalled; and has procured for him the large medal from
the Society for the Encouragement of Arts.

  [43] In his work on the Preparation of Printing Ink; 8vo, London,
  1832.

1. _Linseed oil._--Mr. S. says, that the linseed oil, however long
boiled, unless set fire to, cannot be brought into a proper state for
forming printing ink; and that the flame may be most readily
extinguished by the application of a pretty tight tin cover to the top
of the boiler, which should never be more than half full. The French
prefer nut oil to linseed; but if the latter be old, it is fully as
good, and much cheaper, in this country at least.

2. _Black rosin_ is an important article in the composition of good ink;
as by melting it in the oil, when that ingredient is sufficiently
boiled and burnt, the two combine, and form a compound approximating to
a natural balsam, like that of Canada, which is itself one of the best
varnishes that can be used for printing ink.

3. _Soap._--This is a most important ingredient in printer’s ink, which
is not even mentioned in any of the recipes prior to that in the
Encyclopædia Britannica. For want of soap, ink accumulates upon the face
of the types, so as completely to clog them up after comparatively few
impressions have been taken; it will not wash off without alkaline lyes,
and it skins over very soon in the pot. Yellow rosin soap is the best
for black inks; for those of light and delicate shades, white curd soap
is preferable. Too much soap is apt to render the impression irregular,
and to prevent the ink from drying quickly. The proper proportion has
been hit, when the ink works clean, without clogging the surface of the
types.

4. _Lamp black._--The vegetable lamp black, sold in firkins, takes by
far the most varnish, and answers for making the best ink. See BLACK.

5. _Ivory black_ is too heavy to be used alone as a pigment for printing
ink; but it may be added with advantage by grinding a little of it upon
a muller with the lamp black, for certain purposes; for instance, if an
engraving on wood is required to be printed so as to produce the best
possible effect.

6. _Indigo_ alone, or with an equal weight of prussian blue, added in
small proportion, takes off the brown tone of certain lamp-black inks.
Mr. Savage recommends a little Indian red to be ground in with the
indigo and prussian blue, to give a rich tone to the black ink.

7. _Balsam of capivi_, as sold by Mr. Allen, Plough-court,
Lombard-street, mixed, by a stone and a muller, with a due proportion of
soap and pigment, forms an extemporaneous ink, which the printer may
employ very advantageously when he wishes to execute a job in a
peculiarly neat manner. Canada balsam does not answer quite so well.

After the smoke begins to rise from the boiling oil, a bit of burning
paper stuck in the cleft end of a long stick, should be applied to the
surface, to set it on fire, as soon as the vapour will burn; and the
flame should be allowed to continue (the pot being meanwhile removed
from over the fire, or the fire taken from under the pot,) till a sample
of the varnish, cooled upon a pallet-knife, draws out into strings of
about half an inch long between the fingers. To six quarts of linseed
oil thus treated, six pounds of rosin should be gradually added, as soon
as the froth of the ebullition has subsided. Whenever the rosin is
dissolved, one pound and three quarters of dry brown soap, of the best
quality, cut into slices, is to be introduced cautiously, for its water
of combination causes a violent intumescence. Both the rosin and soap
should be well stirred with the spatula. The pot is to be now set upon
the fire, in order to complete the combination of all the constituents.

Put next of well ground indigo and prussian blue, each 2-1/2 ounces,
into an earthen pan, sufficiently large to hold all the ink, along with
4 pounds of the best mineral lamp black, and 3-1/2 pounds of good
vegetable lamp black; then add the warm varnish by slow degrees,
carefully stirring, to produce a perfect incorporation of all the
ingredients. This mixture is next to be subjected to a mill, or slab and
muller, till it be levigated into a smooth uniform paste.

One pound of a superfine printing ink may be made by the following
recipe of Mr. Savage:--Balsam of capivi, 9 oz.; lamp black, 3 oz.;
indigo and prussian blue, together, p. æq. 1-1/4 oz.; Indian red, 3/4
oz.; turpentine (yellow) soap, dry, 3 oz. This mixture is to be ground
upon a slab, with a muller, to an impalpable smoothness. The pigments
used for coloured printing inks are, carmine, lakes, vermillion, red
lead, Indian red, Venetian red, chrome yellow, chrome red or orange,
burnt _terra di Sienna_, gall-stone, Roman ochre, yellow ochre,
verdigris, blues and yellows mixed for greens, indigo, prussian blue,
Antwerp blue, lustre, umber, sepia, browns mixed with Venetian red, &c.


PRINTING MACHINE. (_Typographie mécanique_, Fr.; _Druckmaschine_, Germ.)
In reviewing those great eras of national industry, when the productive
arts, after a long period of irksome vassalage, have suddenly achieved
some new conquest over the inertia of matter, the contemplative mind
cannot fail to be struck with the insignificant part which the
academical philosopher has generally played in such memorable events.

Engrossed with barren syllogisms, or equational theorems, often little
better than truisms in disguise, he nevertheless believes in the
perfection of his attainments, and disdains to soil his hands with those
handicraft operations at which all improvements in the arts must
necessarily begin. He does not deem manufacture worthy of his regard,
till it has worked out its own grandeur and independence with patient
labour and consummate skill. In this spirit the men of speculative
science neglected for 60 years the steam engine of Newcomen, till the
artisan Watt transformed it into an automatic prodigy; they have never
deigned to illustrate by dynamical investigations the factory
mechanisms of Arkwright, yet nothing in the whole compass of art
deserves it so well; and though perfectly aware that revolvency is the
leading law in the system of the universe, they have never thought of
showing the workman that this was also the true principle of every
automatic machine.

These remarks seem to be peculiarly applicable to book-printing, an art
invented for the honour of learning and the glory of the learned, though
they have done nothing for its advancement; yet by the overruling bounty
of Providence it has eventually served as the great teacher and guardian
of the whole family of man.

It has been justly observed by Mr. Cowper, in his ingenious lecture,[44]
that no improvement had been introduced in this important art, from its
invention till the year 1798, a period of nearly 350 years. In Dr.
Dibdin’s interesting account of printing, in the Bibliographical
Decameron, may be seen representations of the early printing-presses,
which exactly resemble the wooden presses in use at the present day. A
new era has, however, now arrived, when the demands for prompt
circulation of political intelligence require powers of printing
newspapers beyond the reach of the most expeditious hand presswork.

  [44] On the recent improvements in printing, first delivered at the
  Royal Institution, February 22, 1828.

For the first essential modification of the old press, the world is
indebted to the late Earl Stanhope.[45] His press is formed of iron,
without any wood; the table upon which the form of types is laid, as
well as the platen or surface which immediately gives the impression, is
of cast iron, made perfectly level; the platen being large enough to
print a whole sheet at one pull. The compression is applied by a
beautiful combination of levers, which give motion to the screw, cause
the platen to descend with progressively increasing force till it
reaches the type, when the power approaches the maximum; upon the
infinite lever principle, the power being applied to straighten an
obtuse-angled jointed lever. This press, however, like all its
flat-faced predecessors, does not act by a continuous, but a
reciprocating motion, and can hardly be made automatic; nor does it much
exceed the old presses in productiveness, since it can turn off only 250
impressions per hour.

  [45] Lord Stanhope is the only man of learning whose name figures in
  the annals of typography.

[Illustration: 913

Nicholson’s for arched type.]

[Illustration: 914

Nicholson’s for common type.]

The first person who publicly projected a self-acting printing-press,
was Mr. William Nicholson, the able editor of the Philosophical Journal,
who obtained a patent in 1790-1, for imposing types upon a cylindrical
surface; this disposition of types, plates, and blocks, being a new
invention (see _fig._ 913.); 2, for applying the ink upon the surface of
the types, &c., by causing the surface of a cylinder smeared with the
colouring-matter to roll over them; or else causing the types to apply
themselves to the said cylinder. For the purpose of spreading the ink
evenly over this cylinder, he proposed to apply three or more
distributing rollers longitudinally against the inking cylinder, so that
they might be turned by the motion of the latter. 3. “I perform,” he
says, “_all my impressions by the action_ of a cylinder, or cylindrical
surface; that is, I cause the paper to pass between two cylinders, one
of which has the form of types attached to it, and forming part of its
surface; and the other is faced with cloth, and serves to press the
paper so as to take off an impression of the colour previously applied;
or otherwise I cause the form of types, previously coloured, to pass in
close and successive contact with the paper wrapped round a cylinder
with woollen.” (See _figs._ 913. and 914.)[46]

  [46] The black parts in these little diagrams, 913-922, indicate the
  inking apparatus; the diagonal lines, the cylinders upon which the
  paper to be printed is applied; the perpendicular lines, the plates or
  types; and the arrows show the track pursued by the sheet of paper.

In this description Mr. Nicholson indicates pretty plainly the principal
parts of modern printing machines; and had he paid the same attention to
any one part of his invention which he fruitlessly bestowed upon
attempts to attach types to a cylinder, or had he bethought himself of
curving stereotype plates, which were then beginning to be talked of, he
would in all probability have realized a working apparatus, instead of
scheming merely ideal plans.

The first operative printing machine was undoubtedly contrived by, and
constructed under the direction of, M. König, a clockmaker from Saxony,
who, so early as the year 1804, was occupied in improving
printing-presses. Having failed to interest the continental printers in
his views, he came to London soon after that period, and submitted his
plans to Mr. T. Bensley, our celebrated printer, and to Mr. R. Taylor,
now one of the editors of the Philosophical Magazine.

These gentlemen afforded Mr. König and his assistant Bauer, a German
mechanic, liberal pecuniary support. In 1811, he obtained a patent for a
method of working a common hand-press by power; but after much expense
and labour he was glad to renounce the scheme. He then turned his mind
to the use of a cylinder for communicating the pressure, instead of a
flat plate; and he finally succeeded, sometime before the 28th November
1814, in completing his printing automaton; for on that day the editors
of the Times informed their readers that they were perusing for the
first time a newspaper printed by steam-impelled machinery; it is a day,
therefore, which will be ever memorable in the annals of typography.

[Illustration: 915

König’s single, for one side of the sheet.]

In that machine the form of type was made to traverse horizontally under
the pressure cylinder, with which the sheet of paper was held in close
embrace by means of a series of endless tapes. The ink was placed in a
cylindrical box, from which it was extruded by means of a powerful
screw, depressing a well-fitted piston; it then fell between two iron
rollers, and was by their rotation transferred to several other
subjacent rollers, which had not only a motion round their axes, but an
alternating traverse motion (endwise). This system of equalizing rollers
terminated in two which applied the ink to the types. (See _fig._ 915).
This plan of inking evidently involved a rather complex mechanism, was
hence difficult to manage, and sometimes required two hours to get into
good working trim. It has been superseded by a happy invention of Mr.
Cowper, to be presently described.

In order to obtain a great many impressions rapidly from the same form,
a paper-conducting cylinder (one embraced by the paper) was mounted upon
each side of the inking apparatus, the form being made to traverse under
both of them. This double-action machine threw off 1100 impressions per
hour when first finished; and by a subsequent improvement, no less than
1800.

[Illustration: 916

König’s double, for both sides of the sheet.]

Mr. König’s next feat was the construction of a machine for printing
both sides of the newspaper at each complete traverse of the forms. This
resembled two single machines, placed with their cylinders towards each
other, at a distance of two or three feet; the sheet was conveyed from
one paper cylinder to another, as before, by means of tapes; the track
of the sheet exactly resembled the letter S laid horizontally, thus,
[S]; and the sheet was turned over or reversed in the course of its
passage. At the first paper cylinder it received the impression from the
first form, and at the second it received it from the second form;
whereby the machine could print 750 sheets of book letter-press on both
sides in an hour. This new register apparatus was erected for Mr. T.
Bensley, in the year 1815, being the only machine made by Mr. König for
printing upon both sides. See _fig._ 916.

[Illustration: 917

Donkin and Bacon’s for type.]

Messrs. Donkin and Bacon had for some years previous to this date been
busily engaged with printing machines, and had indeed, in 1813, obtained
a patent for an apparatus, in which the types were placed upon the sides
of a revolving prism; the ink was applied by a roller, which rose and
fell with the eccentricities of the prismatic surface, and the sheet was
wrapped upon another prism fashioned so as to coincide with the
eccentricities of the type prism. One such machine was erected for the
University of Cambridge. (See _fig._ 917.) It was a beautiful specimen
of ingenious contrivance and good workmanship. Though it was found to be
too complicated for common operatives, and defective in the mechanism of
the inking process; yet it exhibited for the first time the elastic
inking rollers, composed of glue combined with treacle, which alone
constitute one of the finest inventions of modern typography. In König’s
machine the rollers were of metal covered with leather, and never
answered their purpose very well.

Before proceeding further, I may state that the above elastic
composition, which resembles caoutchouc not a little, but is not so
firm, is made by dissolving with heat, in two pounds of ordinary
treacle, one pound of good glue, previously soaked during a night in
cold water.

[Illustration: 918

Cowper’s single, for curved stereotype.]

[Illustration: 919

Cowper’s double, for both sides of the sheet.]

In the year 1815, Mr. Cowper turned his scientific and inventive mind to
the subject of printing machines, and has since, in co-operation with
his partner, Mr. Applegath, carried them to an unlooked-for degree of
perfection. In 1815 Mr. Cowper obtained a patent for curving stereotype
plates, for the purpose of fixing them on a cylinder Several machines
so mounted, capable of printing 1000 sheets per hour upon both sides,
are at work at the present day; twelve machines on this principle having
been made for the Directors of the Bank of England a short time previous
to their re-issuing gold. See _figs._ 918. and 919.

It deserves to be remarked here, that the same object seems to have
occupied the attention of Nicholson, Donkin, Bacon, and Cowper; viz.,
the revolution, of the form of types. Nicholson sought to effect this by
giving to the shank of a type a shape like the stone of an arch; Donkin
and Bacon by attaching types to the sides of a revolving prism; and
Cowper, more successfully, by curving a stereotype plate. (See _fig._
918.) In these machines Mr. Cowper places two paper cylinders side by
side, and against each of them a cylinder for holding the plates; each
of these four cylinders is about two feet in diameter. Upon the surface
of the stereotype-plate cylinder, four or five inking rollers of about
three inches in diameter are placed; they are kept in their position by
a frame at each end of the said cylinder, and the axles of the rollers
rest in vertical slots of the frame, whereby having perfect freedom of
motion, they act by their gravity alone, and require no adjustment.

The frame which supports the inking rollers, called the waving-frame, is
attached by hinges to the general framework of the machine; the edge of
the stereotype-plate cylinder is indented, and rubs against the
waving-frame, causing it to vibrate to and fro, and consequently to
carry the inking rollers with it, so as to give them an unceasing
traverse movement. These rollers distribute the ink over three-fourths
of the surface of the cylinder, the other quarter being occupied by the
curved stereotype plates. The ink is contained in a trough, which stands
parallel to the said cylinder, and is formed by a metal roller revolving
against the edge of a plate of iron; in its revolution it gets covered
with a thin film of ink, which is conveyed to the plate-cylinder by a
distributing roller vibrating between both. The ink is diffused upon the
plate cylinder as before described; the plates in passing under the
inking rollers become charged with the coloured varnish; and as the
cylinder continues to revolve, the plates come into contact with a sheet
of paper on the first paper cylinder, which is then carried by means of
tapes to the second paper cylinder, where it receives an impression upon
its opposite side from the plates upon the second cylinder.

Thus the printing of the sheet is completed. Though the above machine be
applicable only to stereotype plates, it has been of general importance,
because it formed the foundation of the future success of Messrs. Cowper
and Applegath’s printing machinery, by showing them the best method of
serving out, distributing, and applying the coloured varnish to the
types.

In order to adapt this method of inking to a flat type-form machine, it
was merely requisite to do the same thing upon an extended flat surface
or table, which had been performed upon an extended cylindrical surface.
Accordingly, Messrs. Cowper and Applegath constructed a machine for
printing both sides of the sheet from type, including the inking
apparatus, and the mode of conveying the sheet from the one paper
cylinder to the other, by means of drums and tapes. It is highly
creditable to the scientific judgment of these patentees, that in new
modelling the printing machine, they dispensed with forty wheels, which
existed in Mr. König’s apparatus, when Mr. Bensley requested them to
apply their improvements to it.

[Illustration: 920

Cowper’s inking table and roller.]

The distinctive advantages of these machines, and which have not
hitherto been equalled, are the uniform distribution of the ink, the
equality as well as delicacy with which it is laid upon the types, the
diminution in its expenditure, amounting to one half upon a given
quantity of letter-press, and the facility with which the whole
mechanism is managed. The band inking-roller, and distributing-table,
now so common in every printing-office in Europe and America, is the
invention of Mr. Cowper, and was specified in his patent. The vast
superiority of the inking apparatus in his machines, over the balls used
of old, induced him to apply it forthwith to the common press, and most
successfully for the public; but with little or no profit to the
inventor, as the plan was unceremoniously infringed throughout the
kingdom, by such a multitude of printers, whether rich or poor, as to
render all attempts at reclaiming his rights by prosecution hopeless.
See _fig._ 920.

[Illustration: 921

Applegath and Cowper’s single.]

[Illustration: 922

Applegath and Cowper’s double.]

To construct a printing machine which shall throw off two sides at a
time with exact register, that is, with the second side placed precisely
upon the back of the first, is a very difficult problem, which was
first practically solved by Messrs. Applegath and Cowper. It is
comparatively easy to make a machine which shall print the one side of a
sheet of paper first, and then the other side, by the removal of one
form, and the introduction of another; and thus far did Mr. König
advance. A correct register requires the sheet, after it has received
its first impression from one cylinder, to travel round the peripheries
of the cylinders and drums, at such a rate as to meet the types of the
second side at the exact point which will ensure this side falling with
geometrical nicety upon the back of the first. For this purpose, the
cylinders and drums must revolve at the very same speed as the carriage
underneath; hence the least incorrectness in the workmanship will
produce such defective typography as will not be endured in
book-printing at the present day, though it may be tolerated in
newspapers. An equable distribution of the ink is of no less importance
to beautiful letter-press. See _figs._ 921. 922.

The machines represented in _figs._ 923, 924, 925, are different forms
of those which have been patented by Messrs. Applegath and Cowper. That
shown in _figs._ 923. and 925. prints both sides of the sheet during its
passage, and is capable of throwing off nearly 1000 finished sheets per
hour. The moistened quires of blank paper being piled upon a table A,
the boy, who stands on the adjoining platform, takes up one sheet after
another, and lays them upon the feeder B, which has several linen girths
passing across its surface, and round a pulley at each end of the
feeder; so that whenever the pulleys begin to revolve, the motion of the
girths carries forward the sheet, and delivers it over the entering
roller E, where it is embraced between two series of endless tapes, that
pass round a series of tension rollers. These tapes are so placed as to
fall partly between, and partly exterior to, the pages of the printing;
whereby they remain in close contact with the sheet of paper on both of
its sides during its progress through the machine. The paper is thus
conducted from the first printing cylinder F, to the second cylinder G,
without having the truth of its register impaired, so that the
coincidence of the two pages is perfect. These two great cylinders, or
drums, are made of cast iron, turned perfectly true upon a self-acting
lathe;[47] they are clothed in these parts, corresponding to the
typographic impression, with fine woollen cloth, called _blankets_ by
the pressmen, and revolve upon powerful shafts which rest in brass
bearings of the strong framing of the machine. These bearings, or
plummer blocks, are susceptible of any degree of adjustment, by set
screws. The drums H and I are made of wood; they serve to conduct the
sheet evenly from the one printing cylinder to the other.

  [47] I have witnessed with much pleasure the turning of these great
  cylinders in Messrs. Cowper’s factory at Manchester.

[Illustration: 923 924 925]

One series of tapes commences at the upper part of the entering drum E,
proceeds in contact with the right-hand side and under surface of the
printing cylinder F, passes next over the carrier-drum H, and under the
carrier-drum I; then encompassing the left-hand side and under portion
of the printing drum G, it passes in contact with the small tension
rollers _a_, _b_, _c_, _d_, _fig._ 925., and finally arrives at the
roller E, which may be called the commencement of the one series of
endless tapes. The other series may be supposed to commence at the
roller _h_; it has an equal number of tapes, and corresponds with the
former in being placed upon the cylinders so that the sheets of paper
may be held securely between them. This second series descends from the
roller _h_, _fig._ 925., to the entering drum E, where it meets and
coincides with the first series in such a way that both sets of tapes
proceed together _under_ the printing cylinder F, _over_ H, _under_ I,
and _round_ G, until they arrive at the roller _i_, _fig._ 923., where
they separate, after having continued in contact, except at the places
where the sheets of paper are held between them. The tapes descend from
the roller _i_, to a roller at _k_, and, after passing in contact with
rollers at _l_, _m_, _n_, they finally arrive at the roller _h_, where
they were supposed to commence. Hence two series of tapes act invariably
in contact, without the least mutual interference, as may be seen by
inspection of the _figs._ 923, 924, 925.

The various cylinders and drums revolve very truly by means of a system
of toothed wheels and pinions mounted at their ends. Two horizontal
forms of types are laid at a certain distance apart upon the long
carriage M, adjoining to each of which there is a flat metallic plate,
or inking table, in the same plane. The common carriage, bearing its two
forms of type and two inking tables, is moved backwards and forwards,
from one end of the printing machine to the other, upon rollers attached
to the frame-work, and in its traverse brings the types into contact
with the sheet of paper clasped by the tapes round the surfaces of the
printing cylinders. This alternate movement of the carriage is produced
by a pinion working alternately into the opposite sides of a rack under
the table. The pinion is driven by the bevel wheels K.

The mechanism for supplying the ink, and distributing it over the forms,
is one of the most ingenious and valuable inventions belonging to this
incomparable machine, and is so nicely adjusted, that a single grain of
the pigment may suffice for printing one side of a sheet. Two similar
sets of inking apparatus are provided; one at each end of the machine,
adapted to ink its own form of type. The metal roller L, called the
_ductor_ roller, as it draws out the supply of ink, has a slow rotatory
motion communicated to it by a catgut cord, which passes round a small
pulley upon the end of the shaft of the printing cylinder G. A
horizontal plate of metal, with a straight-ground edge, is adjusted by
set screws, so as to stand nearly in contact with the ductor roller.
This plate has an upright ledge behind, converting it into a sort of
trough or magazine, ready to impart a coating of ink to the roller, as
it revolves over the table. Another roller, covered with elastic
composition (see _suprà_), called the vibrating roller, is made to
travel between the ductor roller and the inking table; the vibrating
roller, as it rises, touches the ductor roller for an instant, abstracts
a film of ink from it, and then descends to transfer it to the table.
There are 3 or 4 small rollers of distribution, placed somewhat
diagonally across the table at M, (inclined only 2 inches from a
parallel to the end of the frame,) furnished with long slender axles,
resting in vertical slots, whereby they are left at liberty to revolve
and to traverse at the same time; by which compound movement they are
enabled to efface all inequality in the surface of the varnish, or to
effect a perfect distribution of the ink along the table. The table
thus evenly smeared, being made to pass under the 3 or 4 proper inking
rollers N, _fig._ 924., imparts to them an uniform film of ink, to be
immediately transferred by them to the types. Hence each time that the
forms make a complete traverse to and fro, which is requisite for the
printing of every sheet, they are touched no less than eight times by
the inking rollers. Both the distributing and inking rollers turn in
slots, which permit them to rise and fall so as to bear with their whole
weight upon the inking table and the form, whereby they never stand in
need of any adjustment by screws, but are always ready for work when
dropped into their respective places.

Motion is given to the whole system of apparatus by a strap from a steam
engine going round a pulley placed at the end of the axle at the back of
the frame; one steam-horse power being adequate to drive two double
printing machines; while a single machine may be driven by the power of
two men acting upon a fly-wheel. In Messrs. Clowes’ establishment, in
Stamford-street, two five-horse engines actuate nineteen of the above
described machines.

The operation of printing is performed as follows:--See _fig._ 926.

The sheets being carefully laid, one by one, upon the linen girths, at
the feeder B, the rollers C and D are made to move, by means of a
segment wheel, through a portion of a revolution. This movement carries
on the sheet of paper sufficiently to introduce it between the two
series of endless tapes at the point where they meet each other upon the
entering drum E. As soon as the sheet is fairly embraced between the
tapes, the rollers C and D are drawn back, by the operation of a weight,
to their original position, so as to be ready to introduce another sheet
into the machine. The sheet, advancing between the endless tapes,
applies itself to the blanket upon the printing cylinder F, and as it
revolves meets the first form of types, and receives their impression;
after being thus printed on one side, it is carried, over H and under I,
to the blanket upon the printing cylinder G, where it is placed in an
inverted position; the printed side being now in contact with the
blanket, and the white side being outwards, meets the second form of
types at the proper instant, so as to receive the second impression, and
get completely printed. The perfect sheet, on arriving at the point _i_,
where the two series of tapes separate, is tossed out by centrifugal
force into the hands of a boy.

[Illustration: 926]

The diagram, _fig._ 926. shows the arrangement of the tapes, agreeably
to the preceding description; the feeder B, with the rollers C and D, is
seen to have an independent endless girth.

[Illustration: 927]

The diagram, _fig._ 927. explains the structure of the great machine
contrived by Messrs. Applegath and Cowper for printing the _Times_
newspaper. Here there are four places to lay on the sheets, and four to
take them off; consequently, the assistance of eight lads is required.
P, P, P, P, are the four piles of paper; F, F, F, F, are the four
feeding-boards; E, E, E, E, are the four entering drums, upon which the
sheets are introduced between the tapes _t_, _t_, _t_, _t_, whence they
are conducted to the four printing cylinders 1, 2, 3, 4; T is the form
of type; I, I, are two inking tables, of which one is placed at each end
of the form. The inking apparatus is similar to that above described,
with the addition of two central inking rollers R, which likewise
receive their ink from the inking tables. The printing cylinders 1, 2,
3, 4, are made to rise and fall about half an inch; the first and third
simultaneously, as also the second and fourth. The form of type, in
passing from A to B, prints sheets at 1 and 3; in returning from B to A,
it prints sheets at 4 and 2; while the cylinder alternately falls to
give the impression, and rises to permit the form to pass untouched.

Each of the lines marked _t_, consists of two endless tapes, which run
in contact at the parts shown, but separate at the entering drums E, and
at the taking off parts _o_, _o_, _o_, _o_. The return of the tapes to
the entering drum is omitted in the diagram, to avoid confusion of the
lines.

The sheets of paper being laid upon their respective feeding-boards,
with the fore edges just in contact with the entering drum, a small
roller, called the drop-down roller, falls, at proper intervals, down
upon the edges of the sheets; the drum and the roller being then
removed, instantly carry on the sheet, between the tapes _t_, downwards
to the printing cylinder, and thence upwards to _o_, _o_, _o_, _o_,
where the tapes are parted, and the sheet falls into the hands of the
attendant boy. This noble mechanism is so perfectly equipped, that it is
generally in full work within four minutes after the form is brought
into the machine-room. The speed of König’s machine, by which the
_Times_ was formerly printed, was such as to turn out 1800 papers per
hour; that of Applegath and Cowper throws off 4200 per hour, and it has
been daily in use during eight years.


PRUSSIAN BLUE, and PRUSSIATE OF POTASH, are two important articles of
chemical manufacture, which must be considered together. The first is
called by English chemists, _Ferrocyanodide of iron_, the _Cyanure
ferroso-ferrique_ of Berzelius; _Eisenblausaures eisenoxyd_, or
_eisencyanür_ + _eisencyanid_, Germ.; the second is called
_Ferrocyanodide of potassium_, the _Cyanure ferroso-potassique_ of
Berzelius; _Eisencyanür-kalium_, _cyaneisen_ + _cyankalium_, or
_Blausaures eisenoxydul-kali_, Germ.

Prussian blue (_Berliner-blau_, Germ.), is a chemical compound of iron
and cyanogen. When organic matters abounding in nitrogen, as dried
blood, horns, hair, skins, or hoofs of animals, are triturated along
with potash in a strongly ignited iron pot, a dark gray mass is
obtained, that affords to water the liquor originally called _lixivium
sanguinis_, or blood-lye, which, by evaporation, yields lemon-coloured
crystals in large rectangular tables, bevelled at the edges. This salt
is called in commerce, prussiate of potash, and has for its ultimate
constituents, potassium, iron, oxygen, and hydrogen, (the latter two in
such proportions as to form water), and the peculiar compound CYANOGEN,
the _blaustoff_ of the Germans.

These crystals consist, in 100 parts, of potassium 37·02, iron 12·82,
cyanogen 37·40, water 12·76; or, cyanide of potassium 61·96, cyanide of
iron 25·28, and water 12·76. They may be represented also by the
following composition: 44·58 of potassa, 38·82 of hydrocyanic or prussic
acid, and 16·60 of oxide of iron, in 100 parts; but the first appears to
be their true chemical constitution. Dry ferrocyanodide of potassium, is
a compound of, one atom of cyanide of iron, 54 = (28 + 26), and 2 atoms
of cyanide of potassium, 132, = ([26 × 2] + [40 × 2]); the sum being
186; hydrogen being 1·0 in the scale of equivalents. The crystals of
prussiate of potash are nearly transparent, soft, of a sweetish saline
and somewhat bitterish taste, soluble in 4 parts of water at 52° F., and
in 1 part of boiling water, but insoluble in alcohol. They are permanent
in the air at ordinary temperatures, but in a moderately warm stove-room
they part with 12-3/4 per cent. of water, without losing their form or
coherence, and become thereby a white friable anhydrous ferrocyanodide
of potassium, consisting of 42·44 potassium, 42·87 cyanogen, and 14·69
iron, in 100 parts.

This salt is an excellent reagent for distinguishing metals from each
other, as the following TABLE of the precipitates which it throws down
from their saline solutions will show:--

  Metallic solutions.      Colour of precipitate.

  Antimony                 white.
  Bismuth                  white.
  Cadmium                  white, a little yellowish.
  Cerium (protoxide)       white, soluble in acids.
  Cobalt                   green, soon turning reddish-gray.
  Copper (protoxide)       white, changing to red.
    Do.  (peroxide)        brown-red.
  Iron (protoxide)         white, rapidly turning blue.
   Do. (peroxide)          dark blue.
  Lead                     white, with a yellowish cast.
  Manganese (protoxide)    white, turning quickly peach or blood-red.
  Manganese (deutoxide)    greenish-gray.
  Mercury (protoxide)      white.
    Do.   (peroxide)       white, turning blue.
  Molybdenum               dark brown.
  Nickel (oxide)           white, turning greenish.
  Palladium (protoxide)    green (gelatinous).
  Silver                   white, turning brown in the light.
  Tantalum                 yellow, dark burned colour.
  Tin (protoxide)          white, (gelatinous).
  Do. (peroxide)           yellow,    do.
  Uranium                  red-brown.
  Zinc                     white.

No precipitations ensue with solutions of the alkaline or earthy salts,
except that of yttria, which is white; nor with those of gold, platinum,
rhodium, iridium, osmium, (in concentrated solutions,) tellurium,
chromium, tungstenium. All the precipitates by the ferrocyanodide of
iron, are double compounds of cyanide of iron with cyanide of the metal
thrown down, which is produced by the reciprocal decomposition of the
cyanide of potassium and the peculiar metallic oxide present in the
solution. The precipitate from the sulphate of copper has a fine brown
colour, and has been used as a pigment; but it is somewhat transparent,
and therefore does not cover well. The precipitate from the peroxide
salts of iron is a very intense prussian blue, called on the continent,
Paris blue. It may be regarded as a compound of prussiate of protoxide
and prussiate of peroxide of iron; or as a double cyanide of the
protoxide and peroxide of iron, as the denomination _cyanure
ferroso-ferrique_ denotes. In numbers, its composition may be therefore
stated thus: prussic or hydrocyanic acid, 48·48; protoxide of iron,
20·73; peroxide of iron, 30·79; or cyanogen, 46·71; iron, 37·36; water,
15·93; which represent its constitution when it is formed by
precipitation with the prussiate of potash or a salt of iron that
contains no protoxide. If the iron be but partially peroxidized in the
salt, it will afford a precipitate, at first pale blue, which turns dark
blue in the air, consisting of a mixture of prussiate of protoxide and
prussiate of peroxide. In fact, the white cyanide of iron (the prussiate
of the pure protoxide), when exposed to the air in a moist condition,
becomes, as above stated, dark blue; yet the new combination formed in
this case through absorption of oxygen, is essentially different from
that resulting from the precipitation by the peroxide of iron, since it
contains an excess of the peroxide in addition to the usual two cyanides
of iron. It has been therefore called _basic_ prussian blue, and, from
its dissolving in pure water, _soluble_ prussian blue.

Both kinds of prussian blue agree in being void of taste and smell, in
attracting humidity from the air when they are artificially dried, and
being decomposed at a heat above 348° F. The neutral or insoluble
prussian blue is not affected by alcohol; the basic, when dissolved in
water, is not precipitated by that liquid. Neither is acted upon by
dilute acids; but they form with concentrated sulphuric acid a white
pasty mass, from which they are again reproduced by the action of cold
water. They are decomposed by strong sulphuric acid at a boiling heat,
and by strong nitric acid at common temperatures; but they are hardly
affected by the muriatic. They become green with chlorine, but resume
their blue colour when treated with disoxidizing reagents. When prussian
blue is digested in warm water along with potash, soda, or lime,
peroxide of iron is separated, and a ferroprussiate of potash, soda, or
lime remains in solution. If the prussian blue has been previously
purified by boiling in dilute muriatic acid, and washing with water, it
will afford by this treatment a solution of ferrocyanodide of potassium,
from which by evaporation this salt may be obtained in its purest
crystalline state. When the powdered prussian blue is diffused in
boiling water, and digested with red oxide of mercury, it parts with all
its oxide of iron, and forms a solution of bi-cyanodide, improperly
called prussiate of mercury; consisting of 79·33 mercury, and 20·67
cyanogen; or, upon the hydrogen equivalent scale, of 200 mercury, and 52
= (26 × 2) cyanogen. When this salt is gently ignited, it affords
gaseous cyanogen. Hydrocyanic or prussic acid, which consists of 1 atom
of cyanogen = 26, + 1 of hydrogen = 1, is prepared by distilling the
mercurial bi-cyanide in a glass retort with the saturating quantity of
dilute muriatic acid. Prussic acid may also be obtained by precipitating
the mercury by sulphuretted hydrogen gas from the solution of its
cyanide; as also by distilling the ferrocyanide of potassium along with
dilute sulphuric acid. Prussic acid is a very volatile light fluid,
eminently poisonous, and is spontaneously decomposed by keeping,
especially when somewhat concentrated.

Having expounded the chemical constitution of prussian blue and
prussiate of potash, I shall now treat of their _manufacture upon the
commercial scale_.

1. _Of blood-lye_, the phlogisticated alkali of Scheele. Among the
animal substances used for the preparation of this lixivium, blood
deserves the preference, where it can be had cheap enough. It must be
evaporated to perfect dryness, reduced to powder, and sifted. Hoofs,
parings of horns, hides, old woollen rags, and other animal offals, are,
however, generally had recourse to, as condensing most azotized matter
in the smallest bulk. Dried funguses have been also prescribed. These
animal matters may either be first carbonized in cast-iron cylinders, as
for the manufacture of _sal ammoniac_ (which see), and the residual
charcoal may be then taken for making the ferroprussiate; or the dry
animal matters may be directly employed. The latter process is apt to be
exceedingly offensive to the workmen and neighbourhood, from the
nauseous vapours that are exhaled in it. Eight pounds of horn (hoofs),
or ten pounds of dry blood, afford upon an average one pound of
charcoal. This must be mixed well with good pearlash, (freed previously
from most of the sulphate of potassa, with which it is always
contaminated,) either in the dry way, or by soaking the bruised charcoal
with a strong solution of the alkali; the proportion being one part of
carbonate of potassa to from 1-1/2 to 2 parts of charcoal, or to about
eight parts of hard animal matter. Gautier has proposed to calcine three
parts of dry blood with one of nitre; with what advantage to the
manufacturer, I cannot discover.

[Illustration: 928]

The pot for calcining the mixture of animal and alkaline matter is
egg-shaped as represented at _a_, _fig._ 928, and is considerably
narrowed at the neck _e_, to facilitate the closing of the mouth with a
lid _i_. It is made of cast iron, about two inches thick in the belly
and bottom; this strength being requisite because the chemical action of
the materials wears the metal fast away. It should be built into the
furnace in a direction sloping downwards, (more than is shown in the
figure,) and have a strong knob _b_, projecting from its bottom to
support it upon the back wall, while its shoulder is embraced at the
arms _c_, _c_, by the brickwork in front. The interior of the furnace is
so formed as to leave but a space of a few inches round the pot, in
order to make the flame play closely over its whole surface. The
fire-door _f_, and the draught-hole _z_, of the ash-pit, are placed in
the posterior part of the furnace, in order that the workmen may not be
incommoded by the heat. The smoke vent _o_, issues through the arched
top _h_ of the furnace, towards the front, and is thence led backwards
by a flue to the main chimney of the factory. _d_ is an iron or stone
shelf, inserted before the mouth of the pot, to prevent loss in
shovelling out the semi-liquid paste. The pot may be half filled with
the materials.

The calcining process is different, according as the animal substances
are fresh or carbonized. In the first case, the pot must remain open, to
allow of diligent stirring of its contents, with a slightly bent flat
iron bar or scoop, and of introducing more of the mixture as the
intumescence subsides, during a period of five or six hours, till the
nauseous vapours cease to rise, till the flame becomes smaller and
brighter, and till a smell of ammonia be perceived. At this time, the
heat should be increased, the mouth of the pot should be shut, and
opened only once every half hour, for the purpose of working the mass
with the iron paddle. When on opening the mouth of the pot, and stirring
the pasty mixture, no more flame rises, the process is finished.

If the animal ingredients are employed in a carbonized state, the pot
must be shut as soon as its contents are brought to ignition by a
briskly urged fire, and opened for a few seconds only every quarter of
an hour, during the action of stirring. At first, a body of flame bursts
forth every time that the lid is removed; but by degrees this ceases,
and the mixture soon agglomerates, and then softens into a paste. Though
the fire be steadily kept up, the flame becomes less and less each time
that the pot is opened; and when it ceases, the process is at an end.
The operation, with a mass of 50 pounds of charcoal and 50 pounds of
purified pearlash, lasts about 12 hours, the first time that the furnace
is kindled; but when the pot has been previously brought to a state of
ignition, it takes only 7 or 8 hours. In a well-appointed factory, the
fire should be invariably maintained at the proper pitch, and the pots
should be worked with relays of operatives.

The molten mass is now to be scooped out with an appropriate iron
shovel, having a long shank, and caused to cool in small portions, as
quickly as possible; but not by throwing it into water, as has sometimes
been prescribed; for in this way a good deal of the cyanogen is
converted into ammonia. If it be heaped up and kept hot in contact with
air, some of the ferrocyanide is also decomposed, with diminution of the
product. The crude mass is to be then put into a pan with cold water,
dissolved by the application of a moderate heat, and filtered through
cloths. The charcoal which remains upon the filter possesses the
properties of decolouring syrups, vinegars, &c., and of destroying
smells in a pre-eminent degree. It may also serve, when mixed with fresh
animal coal, for another calcining operation.

As the iron requisite for the formation of the ferrocyanide is in
general derived from the sides of the pot, this is apt to wear out into
holes, especially at its under side, where the heat is greatest. In this
event, it may be taken out of the furnace, patched up with iron-rust
cement, and re-inserted with the sound side undermost. The erosion of
the pot may be obviated in some measure by mixing iron borings or cinder
(hammerschlag) with the other materials, to the amount of one or two
hundredths of the potash.

The above lixivium is not a solution of pure ferroprussiate; it contains
not a little cyanide of potassium, which in the course of the process
had not absorbed the proper dose of iron to form a ferrocyanide; it
contains also more or less carbonate of potash, with phosphate,
sulphate, hydrogenated sulphuret, muriate, and sulpho-cyanide of the
same base, as well as phosphate of lime; substances derived partly from
the impure potash, and partly from the incinerated animal matters.
Formerly that very complex impure solution was employed directly for the
precipitation of prussian blue; but now, in all well regulated works, it
is converted by evaporation and cooling into crystallized ferroprussiate
of potash. The mother-water is again evaporated and crystallized,
whereby a somewhat inferior ferroprussiate is obtained. Before
evaporating the lye, however, it is advisable to add as much solution of
green sulphate of iron to it, as will re-dissolve the white precipitate
of cyanide of iron which first falls, and thereby convert the cyanide of
potassium, which is present in the liquor, into ferrocyanide of
potassium. The commercial prussiate of potash may be rendered chemically
pure by making its crystals effloresce in a stove, fusing them with a
gentle heat in a glass retort, dissolving the mass in water,
neutralizing any carbonate and cyanide of potash that may be present
with acetic acid, then precipitating the ferroprussiate of potash by the
addition of a sufficient quantity of alcohol, and finally crystallizing
the precipitated salt twice over in water. The sulphate of potassa may
be decomposed by acetate of baryta, and the resulting acetate of potassa
removed by alcohol.

2. _The precipitation of prussian blue._--Green sulphate of iron is
always employed by the manufacturer, on account of its cheapness, for
mixing with solution of the ferroprussiate, in forming prussian blue,
though the red sulphate, nitrate, or muriate of iron would afford a much
richer blue pigment. Whatever salt of iron be preferred, should be
carefully freed from any cupreous impregnation, as this would give the
pure blue a dirty brownish cast. The green sulphate of iron is the most
advantageous precipitant, on account of its affording protoxide, to
convert into ferrocyanide any cyanide of potassium that may happen to be
present in the uncrystallized lixivium. The carbonate of potash in that
lixivium might be saturated with sulphuric acid before adding the
solution of sulphate of iron; but it is more commonly done by adding a
certain portion of alum; in which case, alumina falls along with the
prussian blue; and though it renders it somewhat paler, yet it
proportionally increases its weight; whilst the acid of the alum
saturates the carbonate of potash, and prevents its throwing down
iron-oxide, to degrade by its brown-red tint the tone of the blue. For
every pound of pearlash used in the calcination, from two to three
pounds of alum are employed in the precipitation. When a rich blue is
wished for, the free alkali in the prussian lye may be partly saturated
with sulphuric acid, before adding the mingled solutions of copperas and
alum. One part of the sulphate of iron is generally allowed for 15 or 20
parts of dried blood, and 2 or 3 of horn-shavings or hoofs. But the
proportion will depend very much upon the manipulations; which, if
skilfully conducted, will produce more of the cyanides of iron, and
require more copperas to neutralize them. The mixed solutions of alum
and copperas should be progressively added to the lye as long as they
produce any precipitate. This is not at first a fine blue, but a
greenish gray, in consequence of the admixture of some white cyanide of
iron; it becomes gradually blue by the absorption of oxygen from the
air, which is favoured by agitation of the liquor. Whenever the colour
seems to be as beautiful as it is likely to become, the liquor is to be
run off by a spigot or cock from the bottom of the precipitation vats,
into flat cisterns, to settle. The clear supernatant fluid, which is
chiefly a solution of sulphate of potash, is then drawn off by a syphon;
more water is run on with agitation to wash it, which after settling is
again drawn off; and whenever the washings become tasteless, the
sediment is thrown upon filter sieves, and exposed to dry, first in the
air of a stove, but finally upon slabs of chalk or Paris plaster. But
for several purposes, prussian blue may be best employed in the fresh
pasty state, as it then spreads more evenly over paper and other
surfaces.

A good article is known by the following tests: it feels light in the
hand, adheres to the tongue, has a dark lively blue colour, and gives a
smooth deep trace; it should not effervesce with acids, as when
adulterated with chalk; nor become pasty with boiling water, as when
adulterated with starch. The Paris blue, prepared without alum, with a
peroxide salt of iron, displays, when rubbed, a copper-red lustre, like
indigo. Prussian blue, degraded in its colour by an admixture of free
oxide of iron, may be improved by digestion in dilute sulphuric or
muriatic acid, washing, and drying. Its relative richness in the real
ferroprussiate of iron may be estimated by the quantity of potash or
soda which a given quantity of it requires to destroy its blue colour.

Sulphuretted hydrogen passed through prussian blue diffused in water,
whitens it; while prussic acid is eliminated, sulphur is thrown down,
and the sesquicyanide of iron is converted into the single cyanide. Iron
and tin operate in the same way. When prussian blue is made with two
atoms of ferrocyanide of potassium, instead of one, it becomes soluble
in water.

For the mode of applying this pigment in dyeing, see CALICO-PRINTING.

_Sesquiferrocyanate of potash_, is prepared by passing chlorine gas
through a solution of ferrocyanide of potassium, till it becomes red,
and ceases to precipitate the peroxide salts of iron. The liquor yields,
by evaporation, prismatic crystals, of a ruby-red transparency. They are
soluble in 38 parts of water, and consist of 40·42 parts of
sesquicyanide of iron, and 59·58 of cyanide of potassium. The solution
of this salt precipitates the following metals, as stated in the
table:--

  Bismuth                   pale yellow.
  Cadmium                   yellow.
  Cobalt                    dark brown red.
  Copper (protoxide)        red brown.
   Do.   (peroxide)         yellow green.
  Iron, protoxide salts of  blue.
  Manganese                 brown.
  Mercury (protoxide)       red brown.
  Mercury (peroxide)        yellow.
  Molybdenum                red brown.
  Nickel                    yellow green.
  Silver                    red brown.
  Tin (protoxide)           white.
  Uranium                   red brown.
  Zinc                      orange yellow.


PUMICE-STONE (_Pierre-ponce_, Fr.; _Bimstein_, Germ.); is a spongy,
vitreous-looking mineral, consisting of fibres of a silky lustre,
interlaced with each other in all directions. It floats upon water, is
harsh to the touch, having in mass a mean sp. grav. of 0·914; though
brittle, it is hard enough to scratch glass and most metals. Its colour
is usually grayish white; but it is sometimes bluish, greenish, reddish,
or brownish. It fuses without addition at the blowpipe into a white
enamel. According to Klaproth, it is composed of, silica, 77·5; alumina,
17·5; oxide of iron, 2; potassa and soda, 3; in 100 parts. The acids
have hardly any action upon pumice-stone. It is used for polishing
ivory, wood, marble, metals, glass, &c.; as also skins and parchment.
Pumice-stone is usually reckoned to be a volcanic product, resulting,
probably, from the action of fire upon obsidians. The chief localities
of this mineral are, the islands of Lipari, Ponza, Ischia, and Vulcano.
It is also found in the neighbourhood of Andernach, upon the banks of
the Rhine, in Teneriffe, Iceland, Auvergne, &c. It is sometimes so
spongy as to be of specific gravity 0·37.


PUOZZOLANA, is a volcanic gravelly product, used in making hydraulic
mortar. See CEMENTS and MORTARS.


PURPLE OF CASSIUS, _Gold purple_ (_Pourpre de Cassius_, Fr.;
_Gold-purpur_, Germ.); is a vitrifiable pigment, which stains glass and
porcelain of a beautiful red or purple hue. Its preparation has been
deemed a process of such nicety, as to be liable to fail in the most
experienced hands. The following observations will, I hope, place the
subject upon a surer footing.

The proper pigment can be obtained only by adding to a neutral muriate
of gold a mixture of the protochloride and perchloride of tin. Every
thing depends upon this intermediate state of the tin; for the
protochloride does not afford, even with a concentrated solution of
gold, either a chesnut-brown, a blue, a green, a metallic precipitate,
or one of a purple tone; the perchloride occasions no precipitate
whatever, whether the solution of gold be strong or dilute: but a
properly neutral mixture, of 1 part of crystallized protochloride of
tin, with 2 parts of crystallized perchloride, produces, with 1 part of
crystallized chloride of gold (all being in solution), a beautiful
purple-coloured precipitate. An excess of the protosalt of tin gives a
yellow, blue, or green cast; an excess of the persalt gives a red and
violet cast; an excess in the gold salt occasions, with heat (but not
otherwise), a change from the violet and chesnut-brown precipitate into
red. According to Fuchs, a solution of the sesquioxide of tin in
muriatic acid, or of the sesquichloride in water, serves the same
purpose, when dropped into a very dilute solution of gold.

Buisson prepares gold-purple in the following way. He dissolves, first,
1 gramme of the best tin in a sufficient quantity of muriatic acid,
taking care that the solution is neutral; next, 2 grammes of tin in aqua
regia, composed of 3 parts of nitric acid, and 1 part of muriatic, so
that the solution can contain no protoxide; lastly, 7 grammes of fine
gold in a mixture of 1 part of nitric acid, and 6 of muriatic, observing
to make the solution neutral. This solution of gold being diluted with
3-1/2 litres of water (about 3 quarts), the solution of the perchloride
of tin is to be added at once, and afterwards that of the protochloride,
drop by drop, till the precipitate thereby formed acquires the
wished-for tone; after which it should be edulcorated by washing, as
quickly as possible.

Frick gives the following prescription:--Let tin be set to dissolve in
very dilute aqua regia without heat, till the fluid becomes faintly
opalescent, when the metal must be taken out, and weighed. The liquor is
to be diluted largely with water, and a definite weight of a dilute
solution of gold, and dilute sulphuric acid, is to be simultaneously
stirred into the nitro-muriate of tin. The quantity of solution of gold
to be poured into the tin liquor must be such, that the gold in the one
is to the tin in the other in the ratio of 36 to 10.

Gold-purple becomes brighter when it is dry, but appears still as a
dirty-brown powder. Muriatic acid takes the tin out of the fresh-made
precipitate, and leaves the gold either in the state of metal or of a
blue powder. At a temperature between 212° and 300° Fahr., mercury
dissolves out all the gold from the ordinary purple of Cassius.

Relative to the constitution of gold-purple, two views are entertained:
according to the first; the gold is associated in the metallic state
along with the oxide of tin; according to the second, the gold exists as
a purple oxide along with the sesquioxide or peroxide of tin. Its
composition is differently reported by different chemists. The
constituents, according to--

                                                Gold.    Tin oxide.
  Oberkampf, in the purple precipitate, are     39·82      60·18
                    violet    ditto             20·58      79·42
  Berzelius                                     30·725     69·275
  Buisson                                       30·19      69·81
  Gay Lussac                                    30·89      69·11
  Fuchs                                         17·87      82·13

If to a mixture of protochloride of tin, and perchloride of iron, a
properly diluted solution of gold be added, a very beautiful purple
precipitate of Cassius will immediately fall, while the iron will be
left in the liquid in the state of a protochloride. The purple thus
prepared keeps in the air for a long time without alteration. Mercury
does not take from it the smallest trace of gold,--_Fuchs’ Journal für
Chemie_, t. xv.


PURPLE OF MOLLUSCA, is a viscid liquor, secreted by certain shell-fish,
the _Buccinum lapillus_, and others, which dyes wool, &c. of a purple
colour, and is supposed to be the substance of the Tyrian dye, so highly
prized in antient Rome for producing the imperial purple. See DYEING.


PURPURIC ACID, is an acid obtained by treating uric or lithic acid with
dilute nitric acid. It has a fine purple colour; but has hitherto been
applied to no use in the arts.


PURPURINE, is the name of a colouring principle, supposed by Robiquet
and Colin to exist in madder. Its identity is questionable.


PUTREFACTION, _and its Prevention_. The decomposition of animal bodies,
or of such plants as contain azote in their composition, which takes
place spontaneously when they are exposed to the air, under the
influence of moisture and warmth, is called putrefaction. During this
process, there is a complete transposition of the proximate principles,
the elementary substances combining in new and principally gaseous
compounds. Oxygen is absorbed from the atmosphere, and converted into
carbonic acid; one portion of the hydrogen forms water with the oxygen;
another portion forms, with the azote, the carbon, the phosphorus, and
the sulphur respectively, ammonia, carburetted, phosphuretted, and
sulphuretted hydrogen gases, which occasion the nauseous smell evolved
by putrefying bodies. There remains a friable earthy-looking residuum,
consisting of rotten mould and charcoal. Vegetables which contain no
azote, like the ligneous part of plants, suffer their corresponding
decomposition much more slowly, and with different modifications, but
they are finally converted into vegetable mould. In this process, the
juices with which the plants are filled first enter into the acetous
fermentation under the action of heat and moisture; the acid thereby
generated destroys the cohesion of the fibrous matter, and thus reduces
the solids to a pulpy state. In the progress of the decomposition, a
substance is lastly produced which resembles oxidized extractive, is
soluble in alkalis, and is sometimes called _mould_. This decomposition
of the plants which contain no azote, goes on without any offensive
smell, as none of the above-named nauseous gases are disengaged. When
vegetable matters are mixed with animal, as in the dung of cattle, this
decomposition proceeds more rapidly, because the animalized portion
serves as a ferment to the vegetable. Vegetable acids, resins, fats, and
volatilized oils, are not of themselves subject to putrefaction.

The object of the present article is to detail the principles and
processes, according to which, for various purposes in the arts, the
destruction of bodies by putrefaction may be prevented, and their
preservation in a sound state secured for a longer or a shorter time.

I. CONDITIONS OF THE PREVENTION OF PUTREFACTION.

The circumstances by which putrefaction is counteracted, are, 1. the
chemical change of the azotized juices; 2. the abstraction of the water;
3. the lowering of the temperature; and 4. the exclusion of oxygen.

1. _The chemical change of the azotized juices._--The substance which in
dead animal matter is first attacked with putridity, and which serves to
communicate it to the solid fibrous parts, is albumen, as it exists
combined with more or less water in all the animal fluids and soft
parts. In those vegetables also which putrefy, it is the albumen which
first suffers decomposition; and hence those plants which contain most
of that proximate principle, are most apt to become putrid, and most
resemble, in this respect, animal substances; of which fact, mushrooms,
cabbages, coleworts, &c., afford illustrations. The albumen, when
dissolved in water, very readily putrefies in a moderately warm air; but
when coagulated, it seems as little liable to putridity as fibrin
itself. By this change, it throws off the superfluous water, becomes
solid, and may then be easily dried. Hence, those means which by
coagulation make the albumen insoluble, or form with it a new compound,
which does not dissolve in water, but which resists putrefaction, are
powerful antiseptics. Whenever the albumen is coagulated, the uncombined
water may be easily evaporated away, and the residuary solid matter may
be readily dried in the air, so as to be rendered unsusceptible of
decomposition.

In this way acids operate, which combine with the albumen, and fix it in
a coagulated state, without separating it from its solution: such is the
effect of vinegar, citric acid, tartaric acid, &c.

Tannin combines with the albuminous and gelatinous parts of animals, and
forms insoluble compounds, which resist putrefaction; on which fact the
art of tanning is founded.

Alcohol, oil of turpentine, and some other volatile oils, likewise
coagulate albumen, and thereby protect it from putrescence. The most
remarkable operation of this kind is exhibited by wood vinegar, in
consequence of the _creosote_ contained in it, according to the
discovery of Reichenbach. This peculiar volatile oil has so decided a
power of coagulating albumen, that even the minute portion of it present
in pyrolignous vinegar is sufficient to preserve animal parts from
putrefaction, when they are simply soaked in it. Thus, also, flesh is
cured by wood smoke. Wood tar likewise protects animal matter from
change, by the creosote it contains. The ordinary pyrolignous acid
sometimes contains 5 per cent. of creosote.

In circumstances where a stronger impregnation with this antiseptic oil
may be necessary, common wood vinegar may be heated to 167° F., and
saturated with effloresced Glauber’s salts, by which expedient the oil
is separated and made to float upon the surface of the warm liquid;
whence it should be immediately skimmed off; because, by cooling and
crystallizing, the solution would so diminish in density as to allow the
oil to sink to the bottom; for its specific gravity is considerably
greater than that of water. This oil, which contains, besides creosote,
some other volatile constituents, may be kept dissolved ready for use in
strong vinegar or alcohol. Water takes up of pure creosote only 1-3/4
per cent.; but alcohol dissolves it in every proportion.

The earthy and metallic salts afford likewise powerful means for
separating albumen from its watery solution, their bases having the
property of forming insoluble compounds with it. The more completely
they produce this separation, the more effectually do they counteract
putrefaction. The alkaline salts also, as common salt, sal ammoniac,
saltpetre, and tartar, operate against putrescence, though in a smaller
degree, because they do not precipitate the albumen; but, by abstracting
a part of its water, they render it less liable to become putrid. Among
the earthy salts, alum is the most energetic, as it forms a subsalt
which combines with albumen; it is three times more antiseptic than
common salt, and from seven to eight times more so than saltpetre.
Muriate of soda, however, may be employed along with alum, as is done in
the tawing of sheepskins.

The metallic salts operate still more effectually as antiseptics,
because they form with albumen still more intimate combinations. Under
this head we class the green and red sulphates of iron, the chloride of
zinc, the acetate of lead, and corrosive sublimate; the latter, however,
from its poisonous qualities, can be employed only on special occasions.
Nitrate of silver, though equally noxious to life, is so antiseptic,
that a solution containing only 1/500 of the salt is capable of
preserving animal matters from corruption.

2. _Abstraction of water._--Even in those cases where no separation of
the albumen takes place in a coagulated form, or as a solid precipitate,
by the operation of a substance foreign to the animal juices,
putrefaction cannot go on, any more than other kinds of fermentation, in
bodies wholly or in a great measure deprived of their water. For the
albumen itself runs so much more slowly into putrefaction, the less
water it is dissolved in; and in the desiccated state, it is as little
susceptible of alteration as any other dry vegetable or animal matter.
Hence, the proper drying of an animal substance becomes a universal
preventive of putrescence. In this way fruits, herbs, cabbages, fish,
flesh, may be preserved from corruption. If the air be not cold and dry
enough to cause the evaporation of the fluids before putrescence may
come on, the organic substance must be dried by artificial means, as by
being exposed in thin slices in properly constructed air-stoves. At
temperatures under 140° F., the albumen dries up without coagulation,
and may then be re-dissolved in cold water, with its valuable properties
unaltered. By such artificial desiccation, if flesh is to be preserved
for cooking or boiling, it must not be exposed, however, to so high a
degree of heat, which would harden it permanently, like the baked
mummies of Egypt. Mere desiccation, indeed, can hardly ever be employed
upon flesh. Culinary salt is generally had recourse to, either alone or
with the addition of saltpetre or sugar.

These alkaline salts abstract water in their solution, and,
consequently, concentrate the aqueous solution of the albumen; whence,
by converting the simple watery fluid into salt water, which is in
general less favourable to the fermentation of animal matter than pure
water, and by expelling the air, they counteract putridity. On this
account, salted meat may be dried in the air much more speedily and
safely than fresh meat. The drying is promoted by heating the meat
merely to such a degree as to consolidate the albumen, and eliminate the
superfluous water.

Alcohol operates similarly, in abstracting the water essential to the
putrefaction of animal substances, taking it not only from the liquid
albumen, but counteracting its decomposition, when mixed among the
animal solids. Sugar acts in the same way, fixing in an unchangeable
syrup the water which would otherwise be accessory to the fermentation
of the organic bodies. The preserves of fruits and vegetable juices are
made upon this principle. When animal substances are rubbed with
charcoal powder or sand, perfectly dry, and are afterwards freely
exposed to the air, they become deprived of their moisture, and will
keep for any length of time.

3. _Defect of warmth._--As a certain degree of heat is requisite for the
vinous fermentation, so is it for the putrefactive. In a damp
atmosphere, or in one saturated with moisture, if the temperature stand
at from 70° to 80° F., the putrefaction goes on most rapidly; but it
proceeds languidly at a few degrees above freezing, and is suspended
altogether at that point. The elephants preserved in the polar ices are
proofs of the antiseptic influence of low temperature. In temperate
climates, ice-houses serve the purpose of keeping meat fresh and sweet
for any length of time.

4. _Abstraction of oxygen gas._--As the putrefactive decomposition of a
body first commences with the absorption of oxygen from the atmosphere,
so it may be retarded by the exclusion of this gas. It is not, however,
enough to remove the aerial oxygen from the surface of the body, but we
must expel all the oxygen that may be diffused among the vessels and
other solids, as this portion suffices in general to excite
putrefaction, if other circumstances be favourable. The expulsion is
most readily accomplished by a moderate degree of heat, which, by
expanding the air, evolves it in a great measure, and at the same time
favours the fixation of the oxygen in the extractive matter, so as to
make it no longer available towards the putrefaction of the other
substances. Milk, soup, solution of gelatine, &c., may be kept long in a
fresh state, if they be subjected in an air-tight vessel every other day
to a boiling heat. Oxygenation may be prevented in several ways: by
burning sulphur or phosphorus in the air of the meat receiver; by
filling this with compressed carbonic acid; or with oils, fats, syrups,
&c., and then sealing it hermetically. Charcoal powder recently calcined
is efficacious in preserving meat, as it not only excludes air from the
bodies surrounded by it, but intercepts the oxygen by condensing it.
When butcher-meat is enclosed in a vessel filled with sulphurous acid,
it absorbs the gas, and remains for a considerable time proof against
corruption. The same result is obtained if the vessel be filled with
ammoniacal gas. At the end of 76 days such meat has still a fresh look,
and may be safely dried in the atmosphere.

II. PECULIAR ANTISEPTIC PROCESSES.

Upon the preceding principles and experiments depend the several
processes employed for protecting substances from putrescence and
corruption. Here we must distinguish between those bodies which may be
preserved by any media suitable to the purpose, as anatomical
preparations or objects of natural history, and those bodies which being
intended for food, can be cured only by wholesome and agreeable means.

A common method for preserving animal substances unchanged in property
and texture, is to immerse them in a spirituous liquor containing about
65 or 70 per cent. of real alcohol. Camphor may also be dissolved in it,
and as much common salt as its water will take up. A double fold of
ox-bladder should be bound over the mouth of the vessel, in order to
impede the evaporation of the watery portion of the liquid, and its
upper surface should be coated with a turpentine varnish. Undoubtedly a
little creosote would be of use to counteract the decomposing influence
of the alcohol upon the animal substances. With such an addition, a
weaker spirit, containing no more than 30 per cent. of alcohol, would
answer the purpose.

Instead of alcohol, a much cheaper vehicle is water saturated with
sulphurous acid; and if a few drops of creosote be added, the mixture
will become very efficacious. A solution of red sulphate of iron is
powerfully antiseptic; but after some time it gives a deposit of the
oxide, which disguises the preparation in a great degree.

According to Tauffier, animal substances may be preserved more
permanently by a solution of one part of chloride of tin in 20 parts of
water, sharpened with a little muriatic acid, than even by alcohol.

For preserving animal bodies in an embalmed form, mummy-like, a solution
of chloride of mercury and wood vinegar are most efficacious. As there
is danger in manipulating with that mercurial salt, and as in the
present state of our knowledge of creosote we have it in our power to
make a suitably strong solution of this substance in vinegar or spirit
of wine, I am led to suppose that it will become the basis of most
antiseptic preparations for the future. From the statements of Pliny, it
is plain that wood vinegar was the essential means employed by the
antient Egyptians in preparing their mummies, and that the odoriferous
resins were of inferior consequence.

CURING OF PROVISIONS.

_Flesh._--The ordinary means employed for preserving butcher meat are,
drying, smoking, salting, and pickling or souring.

_Drying of animal fibre._--The best mode of operating is as
follows:--The flesh must be cut into slices from 2 to 6 ounces in
weight, immersed in boiling water for 5 or 6 minutes, and then laid on
open trellis-work in a drying-stove, at a temperature kept steadily
about 122° F., with a constant stream of warm dry air. That the boiling
water may not dissipate the soluble animal matters, very little of it
should be used, just enough for the meat to be immersed by portions in
succession, whereby it will speedily become a rich soup, fresh water
being added only as evaporation takes place. It is advantageous to add a
little salt, and some spices, especially coriander seeds, to the water.
After the parboiling of the flesh has been completed, the soup should be
evaporated to a gelatinous consistence, in order to fit it for forming a
varnish to the meat after it is dried, which may be completely effected
within two days in the oven. By this process two-thirds of the weight is
lost. The perfectly dry flesh must be plunged piece by piece in the
fatty gelatinous matter liquefied by a gentle heat; then placed once
more in the stove, to dry the layer of varnish. This operation may be
repeated two or three times, in order to render the coat sufficiently
uniform and thick. Butcher’s meat dried in this way, keeps for a year,
affords, when cooked, a dish similar to that of fresh meat, and is
therefore much preferable to salted provisions. The drying may be
facilitated, so that larger lumps of flesh may be used, if they be
imbued with some common salt immediately after the parboiling process,
by stratifying them with salt, and leaving them in a proper pickling-tub
for 12 hours before they are transferred to the stove. The first method,
however, affords the more agreeable article.

_Smoking._--This process consists in exposing meat previously salted, or
merely rubbed over with salt, to wood smoke, in an apartment so distant
from the fire as not to be unduly heated by it, and into which the smoke
is admitted by flues at the bottom of the side walls. Here the meat
combines with the empyreumatic acid of the smoke, and gets dried at the
same time. The quality of the wood has an influence upon the smell and
taste of the smoke-dried meat; smoke from beech wood and oak being
preferable to that from fir and larch. Smoke from the twigs and berries
of juniper, from rosemary, peppermint, &c., imparts somewhat of the
aromatic flavour of these plants. A slow smoking with a slender fire is
preferable to a rapid and powerful one, as it allows the empyreumatic
principles time to penetrate into the interior substance, without drying
the outside too much. To prevent soot from attaching itself to the
provisions, they may be wrapped in cloth, or rubbed over with bran,
which may be easily removed at the end of the operation.

The process of smoking depends upon the action of the wood acid, or the
creosote volatilized with it, which operates upon the flesh. The same
change may be produced in a much shorter time by immersing the meat for
a few hours in pyrolignous acid, then hanging it up in a dry air, which,
though moderately warm, makes it fit for keeping, without any taint of
putrescence. After a few days exposure, it loses the empyreumatic smell,
and then resembles thoroughly smoked provisions. The meat dried in this
way is in general somewhat harder than by the application of smoke, and
therefore softens less when cooked, a difference to be ascribed to the
more sudden and concentrated operation of the wood vinegar, which
effects in a few hours what would require smoking for several weeks. By
the judicious employment of pyrolignous acid diluted to successive
degrees, we might probably succeed in imitating perfectly the effect of
smoke in curing provisions.

_Salting._--The meat should be rubbed well with common salt, containing
about one sixteenth of saltpetre, and one thirty-secondth of sugar, till
every crevice has been impregnated with it; then sprinkled over with
salt, laid down for 24 or 48 hours, and, lastly, subjected to pressure.
It must next be sprinkled anew with salt, packed into proper vessels,
and covered with the brine obtained in the act of pressing, rendered
stronger by boiling down. For household purposes it is sufficient to rub
the meat well with good salt, to put it into vessels, and load it with
heavy weights, in order to squeeze out as much pickle as will cover its
surface. If this cannot be had, a pickle must be poured on it, composed
of 4 pounds of salt, 1 pound of sugar, and 2 oz. of saltpetre, dissolved
in 2 gallons of water.

_Pickling with vinegar._--Vinegar dissolves or coagulates the albumen of
flesh, and thereby counteracts its putrescence. The meat should be
washed, dried, and then laid in strong vinegar. Or it may be boiled in
the vinegar, allowed to cool in it, and then set aside with it in a cold
cellar, where it will keep sound for several months.

Fresh meat may be kept for some months in water deprived of its air. If
we strew on the bottom of a vessel a mixture of iron filings and flowers
of sulphur, and pour over them some water which has been boiled, so as
to expel its air, meat immersed in it will keep a long time, if the
water be covered with a layer of oil, from half an inch to an inch
thick. Meat will also keep fresh for a considerable period when
surrounded with oil, or fat of any kind, so purified as not to turn
rancid of itself, especially if the meat be previously boiled. This
process is called potting, and is applied successfully to fish, fowls,
&c.

Prechtl says that living fish may be preserved 14 days without water, by
stopping their mouths with crumbs of bread steeped in brandy, pouring a
little brandy into them, and packing them in this torpid state in straw.
When put into fresh water, they come alive again after a few hours!
_Prechtl, Encyclop. Technologisches, art. Faülniss Abhaltung._

_Eggs._--These ought to be taken new laid. The essential point towards
their preservation is the exclusion of the atmospheric oxygen, as their
shells are porous, and permit the external air to pass inwards, and to
excite putrefaction in the albumen. There is also some oxygen always in
the air cell of the eggs, which ought to be expelled or rendered
inoperative, which may be done by plunging them for 5 minutes in water
heated to 140° F. The eggs must be then taken out, wiped dry, besmeared
with some oil (not apt to turn rancid) or other unctuous matter, packed
into a vessel with their narrow ends uppermost, and covered with
sawdust, fine sand, or powdered charcoal. Eggs coated with gum arabic,
and packed in charcoal, will keep fresh for a year. Lime water, or
rather milk of lime, is an excellent vehicle for keeping eggs in, as I
have verified by long experience. Some persons coagulate the albumen
partially, and also expel the air by boiling the eggs for two minutes,
and find the method successful. When eggs are intended for hatching,
they should be kept in a cool cellar; for example, in a chamber
adjoining an ice-house. Eggs exposed, in the holes of perforated
shelves, to a constant current of air, lose about 3/4 of a grain of
their weight daily, and become concentrated in their albuminous part, so
as to be little liable to putrefy. For long sea voyages, the surest
means of preserving eggs, is to dry up the albumen and yolk, by first
triturating them into a homogeneous paste, then evaporating this in an
air-stove or a water-bath heated to 125°, and putting up the dried mass
in vessels which may be made air-tight. When used, it should be
dissolved in three parts of cold or tepid water.

Grain of all kinds, as wheat, barley, rye, &c., and their flour, may be
preserved for an indefinite length of time, if they be kiln-dried, put
up in vessels or chambers free from damp, and excluded from the air.
Well dried grain is not liable to the depredations of insects.

To preserve fruits in a fresh state, various plans are adopted. Pears,
apples, plums, &c. should be gathered in a sound state, altogether
exempt from bruises, and plucked, in dry weather, before they are fully
ripe. One mode of preservation is, to expose them in an airy place to
dry a little for eight or ten days, and then to lay them in dry sawdust
or chopped straw, spread upon shelves in a cool apartment, so as not to
touch each other. Another method consists in surrounding them with fine
dry sand in a vessel which should be made air-tight, and kept in a cool
place. Some persons coat the fruit, including their stalks, with melted
wax; others lay the apples, &c., upon wicker-work shelves in a vaulted
chamber, and smoke them daily during 4 or 5 days with vine branches or
juniper wood. Apples thus treated, and afterwards stratified in dry
sawdust, without touching each other, will keep fresh for a whole year.

The drying of garden fruits in the air, or by a kiln, is a well-known
method of preservation. Apples and pears of large size should be cut
into thin slices. From 5 to 6 measures of fresh apples, and from 6 to 7
of pears, afford in general one measure of dry fruit, (biffins). Dried
plums, grapes, and currants are a common article of commerce.

Herbs, cabbages, &c., may be kept a long time in a cool cellar, provided
they are covered with dry sand. Such vegetables are in general preserved
for the purposes of food, by means of drying, salting, pickling with
vinegar, or beating up with sugar. Cabbages should be scalded in hot
water previously to drying; and all such plants, when dried, should be
compactly pressed together, and kept in air-tight vessels. Tuberous and
other roots are better kept in an airy place, where they may dry a
little without being exposed to the winter’s frost.

A partial drying is given to various vegetable juices by evaporating
them to the consistence of a syrup, called a rob, in which so much of
the water is dissipated as to prevent them from running into
fermentation. The fruits must be crushed, squeezed in bags to expel the
juices, which must then be inspissated either over the naked fire, or on
a water or steam bath, in the air or in vacuo. Sometimes a small
proportion of spices is added, which tends to prevent mouldiness. Such
extracts may be conveniently mixed with sugar into what are called
conserves.

Salting is employed for certain fruits, as small cucumbers or gherkins,
capers, olives, &c. Even for peas such a method is had recourse to, for
preserving them a certain time. They must be scalded in hot water, put
up in bottles, and covered with saturated brine, having a film of oil on
its surface, to exclude the agency of the atmospheric air. Before being
used, they must be soaked for a short time in warm water, to extract the
salt. The most important article of diet of this class, is the _sour
kraut_ of the northern nations of Europe, (made from white cabbage,)
which is prepared simply by salting; a little vinegar being formed
spontaneously by fermentation. The cabbage must be cut into small
pieces, stratified in a cask along with salt, to which juniper berries
and carui seeds are added, and packed as hard as possible by means of a
wooden rammer. The cabbage is then covered with a lid, on which a heavy
weight is laid. A fermentation commences, which causes the cabbage to
become more compact, while a quantity of juice exudes and floats on the
surface, and a sour smell is perceived towards the end of the
fermentation. In this condition the cask is transported into a cool
cellar, where it is allowed to stand for a year; and indeed, where, if
well made and packed, it may be kept for several years.

The excellent process for preserving all kinds of butcher meat, fish,
and poultry, first contrived by M. Appert in France, and afterwards
successfully practised upon the great commercial scale by Messrs. Donkin
and Gamble, for keeping beef, salmon, soups, &c. perfectly fresh and
sweet for exportation from this country, as also turtle for importation
thither from the West Indies, deserves a brief description.

Let the substance to be preserved be first parboiled, or rather somewhat
more, the bones of the meat being previously removed. Put the meat into
a tin cylinder, fill up the vessel with seasoned rich soup, and then
solder on the lid, pierced with a small hole. When this has been done,
let the tin vessel thus prepared be placed in brine and heated to the
boiling point, to complete the remainder of the cooking of the meat. The
hole of the lid is now to be closed perfectly by soldering, whilst the
air is rarefied. The vessel is then allowed to cool, and from the
diminution of the volume, in consequence of the reduction of
temperature, both ends of the cylinder are pressed inwards, and become
concave. The tin cases, thus hermetically sealed, are exposed in a
test-chamber, for at least a month, to a temperature above what they are
ever likely to encounter; from 90° to 110° of Fahrenheit. If the process
has failed, putrefaction takes place, and gas is evolved, which, in
process of time, will cause both ends of the case to bulge, so as render
them convex, instead of concave. But the contents of those cases which
stand the test will infallibly keep perfectly sweet and good in any
climate, and for any number of years. If there be any taint about the
meat when put up, it inevitably ferments, and is detected in the proving
process. Mr. Gamble’s turtle is delicious.

This preservative process is founded upon the fact, that the small
quantity of oxygen contained within the vessel gets into a state of
combination, in consequence of the high temperature to which the animal
substances are exposed, and upon the chemical principle, that free
oxygen is necessary as a ferment to commence or give birth to the
process of putrefaction.

I shall conclude this article with some observations upon the means of
preserving water fresh on sea voyages. When long kept in wooden casks,
it undergoes a kind of putrefaction, contracts a disagreeable
sulphureous smell, and becomes undrinkable. The influence of the
external air is by no means necessary to this change, for it happens in
close vessels even more readily than when freely exposed to the
atmospherical oxygen. The origin of this impurity lies in the animal and
vegetable juices which the water originally contained in the source from
which it was drawn, or from the cask, or insects, &c. These matters
easily occasion, with a sufficient warmth, fermentation in the stagnant
water, and thereby cause the evolution of offensive gases. It would
appear that the gypsum of hard waters is decomposed, and gives up its
sulphur, which aggravates the disagreeable odour; for selenitic waters
are more apt to take this putrid taint, than those which contain merely
carbonate of lime.

As the corrupted water has become unfit for use merely in consequence of
the admixture of these foreign matters, for water in itself is not
liable to corruption, so it may be purified again by their separation.
This purification may be accomplished most easily by passing the water
through charcoal powder, or through the powder of rightly calcined
bone-black. The carbon takes away not only the finely diffused corrupt
particles, but also the gaseous impurities. By adding to the water a
very little sulphuric acid, about 30 drops to 4 pounds, Lowitz says that
two-thirds of the charcoal may be saved. Undoubtedly the sulphuric acid
acts here, as in other similar cases, by the coagulation and separation
of the albuminous matters, combining with them, and rendering them more
apt to be seized by the charcoal. A more effectual agent for the
purification of foul water is to be found in alum. A dram of pounded
alum should be dissolved with agitation in a gallon of the water, and
then left to operate quietly for 24 hours. A sediment falls to the
bottom, while the water becomes clear above, and may be poured off. The
alum combines here with the substances dissolved in the water, as it
does with the stuffs in the dyeing copper. In order to decompose any
alum which may remain in solution, the equivalent quantity of crystals
of carbonate of soda may be added to it.

The red sulphate of iron acts in the same way as alum. A few drops of
its solution are sufficient to purge a pound of foul water. The foreign
matters dissolved in the water, which occasion putrefaction, become
insoluble, in consequence of oxidizement, like vegetable extractive, and
are precipitated. On this account, also, foul water may be purified, by
driving atmospheric air through it with bellows, or by agitating it in
contact with fresh air, so that all its particles are exposed to oxygen.
Thus we can explain the influence of streams and winds, in counteracting
the corruption of water exposed to them. Chlorine acts still more
energetically than the air in purifying water. A little aqueous chlorine
added to foul water, or the transmission of a little gaseous chlorine
through it, cleanses it immediately.

Water-casks ought to be charred inside, whereby no fermentable stuff
will be extracted from the wood. British ships, however, are now
commonly provided with iron tanks for holding their water in long
voyages.


PYRITES, is the native bisulphuret of iron. Copper pyrites, called
vulgarly mundick, is a bisulphuret of copper.


PYRO-ACETIC SPIRIT. (_Esprit pyro-acétique_, _Acétone_, Fr.;
_Brennzlicher Essiggeist_, _Mesit_, Germ.) This liquid was discovered
and described by Chenevix long before _pyrolignous spirit_ was known. It
may be obtained by subjecting to dry distillation the acetates of
copper, lead, alkalis, and earths; and as it is formed especially during
the second half of the process, the liquor which comes over then should
be set apart, separated by decantation from the empyreumatic oil, and
distilled a second time by the heat of a water-bath. The fine light
fluid which now comes over first, is to be rectified along with
carbonate of potassa, or chloride of calcium. As pyro-acetic spirit
usually retains, even after repeated distillations, a disagreeable
empyreumatic smell, like garlic, a little good bone-black should be
employed in its final rectification. According to Reichenbach,
pyro-acetic spirit may be extracted in considerable quantity from beech
tar. (See the next article.) The spirit thus prepared, is a colourless
limpid liquid, of an acrid and burning taste at first, but afterwards
cooling; of a penetrating aromatic smell, different from that of
alcohol; of the spec. gravity 0·7921 at 60° F., boiling at 132° F., and
remaining fluid at 5°. It consists ultimately of--carbon, 62·148;
hydrogen, 10·453; oxygen, 27·329; or, of 1 proportion of carbonic acid +
2 prop. of olefiant gas + 1 prop. of water; or, 1 prop. of acetic
acid--1 prop. of carbonic acid. According to another view, it is
composed of, 51·52 parts of concentrated acetic acid, and 48·488 of oil
of wine, being double of the quantity in acetic ether. It is very
combustible, and burns with a brilliant flame, without smoke. When
treated by chlorine, it loses an atom of its hydrogen, and absorbs 2
atoms of chlorine. It is soluble in water, alcohol, ether, and is not
convertible into ether by strong sulphuric acid. It is used for
dissolving the resins commonly called gums, with which the bodies of
hats are stiffened.


PYROLIGNOUS ACID. In addition to what has been said under ACETIC ACID, I
shall here describe the process as conducted upon a great scale at an
establishment near Manchester. The retorts are of cast iron, 6 feet
long, and 3 feet 8 inches in diameter. Two of these cylinders are heated
by one fire, the flame of which plays round their sides and upper
surface; but the bottom is shielded by fire-tiles from the direct action
of the fire. 2 cwts. of coals are sufficient to complete the
distillation of one charge of wood; 36 imperial gallons of crude
vinegar, of specific gravity 1·025, being obtained from each retort. The
process occupies 24 hours. The retort-mouth is then removed, and the
ignited charcoal is raked out for extinction into an iron chest, having
a groove round its edges, into which a lid is fitted.

When this pyrolignous acid is saturated with quicklime, and distilled,
it yields one per cent. of pyroxilic spirit (sometimes called naphtha);
which is rectified by two or three successive distillations with
quicklime.

The tarry deposit of the crude pyrolignous acid, being subjected to
distillation by itself, affords a crude pyro-acetic ether, which may
also be purified by re-distillation with quicklime, and subsequent
agitation with water.

The pyrolignite of lime, is made by boiling the pyrolignous acid in a
large copper, which has a sloping spout at its lip, by which the tarry
scum freely flows over, as it froths up with the heat. The fluid
compound thus purified, is syphoned off into another copper, and mixed
with a quantity of alum equivalent to its strength, in order to form the
red liquor, or acetate of alumina, of the calico-printer. The acetate of
lime, and sulphate of alumina and potash, mutually decompose each other;
with the formation of sulphate of lime, which falls immediately to the
bottom.

M. Kestner, of Thann, in Alsace, obtains, in his manufactory of
pyrolignous acid, 5 hectolitres (112 gallons imperial, nearly,) from a
cord containing 93 cubic feet of wood. The acid is very brown, much
loaded with tar, and marks 5° Baumé; 220 kilogrammes of charcoal are
left in the cylinders; 500 litres of that brown acid produce, after
several distillations, 375 of the pyrolignous acid of commerce,
containing 7 per cent. of acid, with a residuum of 40 kilogrammes of
pitch. For the purpose of making a crude acetate of lead (pyrolignite),
he dries pyrolignite of lime upon iron plates, mixes it with the
equivalent decomposing quantity of sulphuric acid, previously diluted
with its own weight of water, and cooled; and transfers the mixture as
quickly as possible into a cast-iron cylindric still, built horizontally
in a furnace; the under half of the mouth of the cylinder being always
cast with a semicircle of iron. The acetic acid is received into large
salt-glazed stone bottles. From 100 parts of acetate of lime, he obtains
133 of acetic acid, at 38° Baumé. It contains always a little sulphurous
acid from the reaction of the tar and the sulphuric acid.

[Illustration: 929, 930]

The apparatus represented in _figs._ 929. and 930. is a convenient
modification of that exhibited under acetic acid, for producing
pyrolignous acid. _Fig._ 929. shows the furnace in a horizontal section
drawn through the middle of the flue which leads to the chimney. _Fig._
930. is a vertical section taken in the dotted line x, x, of _fig._ 929.
The chest _a_ is constructed with cast-iron plates bolted together, and
has a capacity of 100 cubic feet. The wood is introduced into it through
the opening _b_, in the cover, for which purpose it is cleft into
billets of moderate length. The chest is heated from the subjacent grate
_c_, upon which the fuel is laid, through the fire-door _d_. The flame
ascends spirally through the flues _e_, _e_, round the chest, which
terminate in the chimney _f_. An iron pipe _g_ conveys the vapours and
gaseous products from the iron chest to the condenser. This consists of
a series of pipes laid zigzag over each other, which rest upon a
framework of wood. The condensing tubes are enclosed in larger pipes
_i_, _i_; a stream of cold water being caused to circulate in the
interstitial spaces between them. The water passes down from a trough
_k_, through a conducting tube _l_, enters the lowest cylindrical case
at _m_, flows thence along the series of jackets _i_, _i_, _i_, being
transmitted from the one row to the next above it, by the junction tubes
_o_, _o_, _o_, till at _p_ it runs off in a boiling-hot state. The
vapours proceeding downwards in an opposite direction to the cooling
stream of water, get condensed into the liquid state, and pass off at
_q_, through a discharge pipe, into the first close receiver _r_, while
the combustible gases flow off through the tube _s_, which is provided
with a stopcock to regulate the magnitude of their flame under the
chest. As soon as the distillation is fully set agoing, the stopcock
upon the gas-pipe is opened; and after it is finished, it must be shut.
The fire should be supplied with fuel at first, but after some time the
gas generated keeps up the distilling heat. The charcoal is allowed to
cool during 5 or 6 hours, and is then taken out through an aperture in
the back of the chest, which corresponds to the opening _u_, _fig._
929., in the brickwork of the furnace. About 60 per cent. of charcoal
may be obtained from 100 feet of fir-wood, with a consumption of as much
brush-wood for fuel.

Stoltze has ascertained, by numerous experiments, that one pound of wood
yields from 6 to 7-1/2 ounces of liquid products; but in acetic acid it
affords a quantity varying from 2 to 5, according to the nature of the
wood. Hard timber, which has grown slowly upon a dry soil, gives the
strongest vinegar. White birch and red beech afford per pound 7-1/3
ounces of wood vinegar, 1-1/3 ounce of combustible oil, and 4 ounces of
charcoal. One ounce of that vinegar saturates 110 grains of carbonate of
potassa. Red pine yields per pound 6-1/2 ounces of vinegar, 2-1/4 ounces
of oil, 3-3/4 ounces of charcoal; but one ounce of the vinegar saturates
only 44 grains of carbonate of potassa, and has therefore only
two-fifths of the strength of the vinegar from the birch. An ounce of
the vinegar from the white beech, holly oak (_Ilex_), common ash, and
horse chesnut, saturates from 90 to 100 grains of the carbonate. In the
same circumstances, an ounce of the vinegar of the alder and white pine
saturates from 58 to 60 grains.


PYROLIGNOUS or PYROXILIC SPIRIT, improperly called naphtha. This is
employed, as well as pyroacetic ether, to dissolve the sandarach,
mastic, and other resinous substances, which, under the name of gums,
are used for stiffening the bodies of hats. I have already described, in
the article PYROLIGNOUS ACID, how this spirit is obtained. Berzelius has
found that the crude spirit may be best purified by agitating it with a
fat oil, in order to abstract the empyreumatic oil; then to decant the
spirit, distil it, first with fresh calcined charcoal, and next with
chloride of calcium. The pyrolignous spirit, thus purified, is
colourless, and limpid like alcohol; has an ethereous smell, somewhat
resembling that of ants. Its taste is hot, and analogous to that of oil
of peppermint. Its specific gravity, by my experiments, is 0·824. It
readily takes fire, and burns with a blue flame, without smoke. It
combines with water in any proportion; a property which distinguishes it
from pyroacetic ether and spirit.

It is not easy to say what is the real chemical nature of pyroxilic
spirit. There is no ultimate analysis of it that can be depended upon.
The properties of the spirit examined by MM. Marcet and Macaire, differ
from those of our spirit, in refusing to combine with water, like
alcohol. The article on sale in this country readily unites with water,
and in all proportions with alcohol.


PYROMETER, is the name of an instrument for measuring high degrees of
heat above the range of the mercurial thermometer. Wedgewood’s is the
one commonly referred to by writers upon porcelain and metallurgy; but a
better one might be easily contrived.


PYROPHORUS, is the generic name of any chemical preparation, generally a
powder, which inflames spontaneously when exposed to the air.


PYROTECHNY. See FIRE-WORKS.


PYROXILINE, is a name which I have ventured to give to a substance
detected in pyroxilic spirit, by Mr. Scanlan, while residing in Dublin,
and therefore called by him _Eblanin_. I am indebted to that ingenious
chemist for the following facts.

If potash water be added to raw wood-spirit (_pyrolignous_), as long as
it throws down any thing, a precipitate is produced, which is
_pyroxiline_, mixed with tarry matter. This precipitate is to be
collected on a filter cloth, and submitted to strong pressure between
folds of blotting-paper; it is next to be washed with cold alcohol,
spec. grav. 0·840, in order to free it from any adhering tarry matter;
when the pyroxiline is left nearly pure. If it be dissolved in boiling
alcohol, or hot oil of turpentine, it crystallizes regularly on cooling,
in right square prisms, of a fine yellow colour, that look opaque to the
naked eye, but when examined under the microscope, have the transparency
and colour of ferroprussiate of potash. Its turpentine solution affords
crystals of a splendid orange-red colour, having the appearance of
minute plates, whose form is not discernible by the naked eye, but when
examined by the microscope, they are seen to be thin right rectangular
prisms. The orange-red colour is only the effect of aggregation; for
when ground to powder, these crystals become yellow; and under the
microscope, the difference in colour between the two is very slight. Its
melting point is 318° F. It sublimes at 300° in free air; heated in a
close tube in a bath of mercury, it emits vapour at 400°; it then begins
to decompose, and is totally decomposed at 500°. Sulphuric acid
decomposes it, producing a beautiful blue colour, which passes into
crimson, as the acid attracts water from the atmosphere, and it totally
disappears on plentiful dilution with water, leaving carbon of a
dirty-brown colour. Its alcoholic or turpentine solution imparts a
permanent yellow dye to vegetable or animal matter.

Pyroxiline consists, according to the analysis of Drs. Apjohn and
Gregory, of--carbon, 75·275; hydrogen, 5·609; oxygen, 19·116, in 100
parts.




Q.


QUARTATION, is the alloying of one part of gold that is to be refined,
along with three parts of silver, so that the gold shall constitute one
_quarter_ of the whole, and thereby have its particles too far separated
to be able to protect the other metals originally associated with it,
such as silver, copper, lead, tin, palladium, &c., from the action of
the nitric or sulphuric acid employed in the subsequent parting process.
See REFINING.


QUARTZ, has been described in the article LAPIDARY.


QUASSIA, is the wood of the root of the _Quassia excelsa_, a tree which
grows in Surinam, the East Indies, &c. It affords to water an intensely
bitter decoction, which is occasionally used in medicine, and was
formerly substituted by some brewers for hops, but is now prohibited
under severe penalties. It affords a safe and efficacious fly-water, or
poison for flies.


QUEEN’s WARE. See POTTERY.


QUEEN’s YELLOW, is an antient name of Turbith Mineral, or yellow
subsulphate of mercury.


QUERCITRON, is the bark of the _Quercus nigra_, or yellow oak, a tree
which grows in North America, The colouring principle of this yellow
dye-stuff has been called _Quercitrin_, by its discoverer Chevreul. It
forms small pale yellow spangles, like those of _Aurum musivum_, has a
faint acid reaction, is pretty soluble in alcohol, hardly in ether, and
little in water. Solution of alum developes from it, by degrees, a
beautiful yellow dye. See CALICO-PRINTING and YELLOW DYE.


QUICKLIME; see LIME.


QUICKSILVER; see MERCURY.


QUILL; see FEATHERS.


QUININA. This medicine is now prepared in such quantities as to
constitute a chemical manufacture. Quinina and cinchonina are two
vegetable alkalis, which exist in Peruvian bark or cinchona; the pale or
gray bark contains most cinchonina, and the yellow bark most quinina.
The methods of extracting these bases are very various. In general,
water does not take them out completely, because it transforms the
neutral salts in the barks into more soluble acidulous salts, and into
less soluble sub-salts. To exhaust the bark completely, one or other of
the following solvents is employed:

1. _Alcohol._--An extract by this menstruum, is to be treated with very
dilute warm muriatic acid, in order to dissolve every thing thus
soluble; the acid liquor is to be saturated with magnesia, by boiling it
with an excess of this earth; the precipitate is to be dried, filtered,
and then exhausted by boiling-hot alcohol.

2. _Dilute acids._--Boil the bark, coarsely pounded, with eight times
its weight of water, containing 5 per cent. of the weight of the bark of
sulphuric acid. This treatment is to be repeated with a fresh quantity
of dilute acid. The whole liquors must be filtered, the residuum
strained, and the solution mixed with quicklime, equal to one fourth of
the bark employed. This mixture, after having been well stirred, is to
be strained, whenever it acquires an alkaline reaction, that is, tinges
reddened litmus paper blue, or turmeric brown. The calcareous mass is to
be now washed with a little water, and dried, and then boiled thrice
with spirit of wine of sp. grav. 0·836. This solution being filtered, is
to be mixed with a little water, and distilled. The bases, cinchonina
and quinina, remain under the form of a brown viscid mass, and must be
purified by subsequent crystallization, after being converted into
sulphates.

3. _An alkali, and then an acid._--The object of this process is, to
retain the vegetable alkalis in the bark, while with the alkaline water
we dissolve out the acids, the colouring matters, the extractive, the
gum, &c. Boil for an hour one pound of the bark with six pounds of
water, adding by degrees a little solution of potash, so that the liquor
may have still an alkaline taste when the boiling is over. Allow it to
cool, filter, wash the residuum with a little water, and squeeze it.
Diffuse it next in tepid water, to which add by degrees a little
muriatic acid, till after a prolonged digestion the mixture shall
perceptibly redden litmus paper. Filter the liquor, and boil it with
magnesia. The precipitate being washed and dried, is to be treated with
hot alcohol, which dissolves the quinina and cinchonina.

Obtained by any of the above methods, the quinina and cinchonina are
more or less coloured, and may be blanched by dissolving them in dilute
muriatic acid, and treating the solution with animal charcoal.

There are several methods of separating these two vegetable alkalis.

1. When their solution in spirit of wine is evaporated by heat to a
certain point, the greater part of the cinchonina crystallizes on
cooling, while the quinina remains dissolved.

2. Digestion in ether dissolves the quinina, and leaves the cinchonina.

3. We may supersaturate slightly the two bases with sulphuric acid. Now
as the supersulphate of quinina is sparingly soluble, the liquor need
only to be evaporated to a proper point to crystallize out that salt,
while the supersulphate of cinchonina continues in solution with very
little of the other salt. Even this may be separated by precipitating
the bases, and treating them, as above prescribed, with alcohol or
ether.

One pound of bark rarely yields more than 2 drams of the bases. One
pound of red bark afforded, to Pelletier and Caventou, 74 grains of
cinchonina, and 107 grains of quinina.

Quinina is composed of 75·76 carbon, 7·52 hydrogen, 8·11 azote, and 8·61
oxygen.

The salts of quinina are distinguished by their strong taste of Peruvian
bark, and if crystallized, by their pearly lustre. Most of them are
soluble in water, and some also in ether and alcohol. The soluble salts
are precipitated by the oxalic, gallic, and tartaric acids, and by the
salts of these acids. Infusion of nutgalls also precipitates them.

The sulphate of quinina is the only object of manufacturing operations.
Upon the brownish viscid mass obtained in any of the above processes for
obtaining quinina, pour very dilute sulphuric acid, in sufficient
quantity to produce saturation. The solution must be then treated with
animal charcoal, filtered, evaporated, allowed to cool, when it deposits
crystals. 1000 parts of bark afford, upon an average, 12 parts of
sulphate. The sulphate of cinchonina, which is formed at the same time,
remains dissolved in the mother-waters.

The neutral sulphate of quinina occurs in small transparent right
prismatic needles. By spontaneous evaporation of their solution, larger
crystals may be procured. They contain 24-2/3 per cent. of water; and,
therefore, melt when exposed to heat. They dissolve in 11 parts of water
at ordinary temperatures; are much more soluble in hot spirit of wine,
somewhat dilute, than in cold; and are nearly insoluble in anhydrous
alcohol. If they be well dried, they possess the property of becoming
luminous when heated a little above the boiling point of water,
especially when they are rubbed. The sulphate is, in this case, charged
with vitreous electricity.

There is a sub-sulphate, but it is applied to no use. The effloresced
sulphate, called by some bisulphate, is preferred for medical practice.
The extensive sale and high price of sulphate of quinina, have given
rise to many modes of adulteration. It has been mixed with boracic acid,
margaric acid, sugar, sugar of manna, gypsum, &c. By incinerating a
little of the salt upon a slip of platina, the boracic acid and gypsum
remain, while the quinine is dissipated; sugar and margaric acid exhale
their peculiar smoke and smell; or they may be dissolved out by a few
drops of water. Cinchonina may be detected by adding ammonia to the
solution, and treating the precipitate with ether, which leaves that
vegeto-alkali.


QUINTESSENCE. The alchemists understood by this term, now no longer in
scientific use, the solution in alcohol of the principles which this
menstruum can extract from aromatic plants or flowers, by digestion,
during some days, in the sun, a stove, or upon a sand-bath slightly
warmed. A quintessence, therefore, corresponds to the alcoholic tincture
or essence (not essential oil) of the present day. See PERFUMERY.




R.


RAISINS, are grapes allowed to ripen and dry upon the vine. The best
come from the south of Europe, as from Roquevaire in Provence, Calabria,
Spain, and Portugal. Fine raisins are also imported from Smyrna,
Damascus, and Egypt. Sweet fleshy grapes are selected for maturing into
raisins, and such as grow upon the sunny slopes of hills sheltered from
the north winds. The bunches are pruned, and the vine is stripped of its
leaves, when the fruit has become ripe; the sun then beaming full upon
the grapes, completes their saccharification, and expels the superfluous
water. The raisins are plucked, cleansed, and dipped for a few seconds
in a boiling lye of wood ashes and quicklime, at 12 or 13 degrees of
Baumé’s areometer. The wrinkled fruit is lastly drained, dried, and
exposed in the sun upon hurdles of basket-work during 14 or 15 days.

The finest raisins are those of the sun, so called; being the plumpest
bunches, which are left to ripen fully upon the vine, after their stalks
have been half cut through.

The amount of raisins imported for home consumption was, in the year
1836, 156,495 cwts.; in 1837, 152,635 cwts.


RAPE-SEED, imported for home consumption in 1836, 561,457 bushels; in
1837, 937,526 bushels. See OILS, UNCTUOUS.


RASP, MECHANICAL, is the name given by the French to an important
machine much used for mashing beet-roots. See SUGAR.


RATAFIA, is the generic name, in France, of _liqueurs_ compounded with
alcohol, sugar, and the odoriferous or flavouring principles of
vegetables. Bruised cherries with their stones are infused in spirit of
wine to make the ratafia of Grenoble _de Teyssère_. The liquor being
boiled and filtered, is flavoured, when cold, with spirit of _noyau_,
made by distilling water off the bruised bitter kernels of apricots, and
mixing it with alcohol. Syrup of bay laurel and galango are also added.


REALGAR, _Red Orpiment_. (_Arsenic rouge sulphuré_, Fr.; _Rothes
schwefelarsenik_, Germ.) This ore occurs in primitive mountains,
associated sometimes with native arsenic, under the form of veins,
efflorescences, very rarely crystalline; as also in volcanic districts;
for example, at Solfatara near Naples; or sublimed in the shape of
stalactites, in the rents and craters of Etna, Vesuvius, and other
volcanoes. Its spec. grav. varies from 3·3 to 3·6. It has a fine scarlet
colour in mass, but orange-red in powder, whereby it is distinguishable
from cinnabar. It is soft, sectile, readily scratched by the nail; its
fracture is vitreous and conchoidal. It volatilizes easily before the
blowpipe, emitting the garlic smell of arsenic, along with that of
burning sulphur. It consists of, arsenic 70, sulphur 30, in 100 parts.
It is employed sometimes as a pigment. Factitious orpiment is made by
distilling, in an earthen retort, a mixture of sulphur and arsenic, of
orpiment and sulphur, or of arsenious acid, sulphur, and charcoal. It
has not the rich colour of the native pigment, and is much more
poisonous; since, like factitious orpiment, it always contains more or
less arsenious acid.


RECTIFICATION, is a second distillation of alcoholic liquors, to free
them from whatever impurities may have passed over in the first.


RED LIQUOR, is a crude acetate of alumina, employed in calico-printing,
and prepared from pyrolignous acid; which see.


REED, is the well-known implement of the weaver, made of parallel slips
of metal or reeds, called dents. A thorough knowledge of the adaptation
of yarn of a proper degree of fineness to any given measure of reed,
constitutes one of the principal objects of the manufacturer of cloths;
as upon this depends entirely the appearance, and in a great degree the
durability, of the cloth when finished. The art of performing this
properly, is known by the names of _examining_, _setting_, or _sleying_,
which are used indiscriminately, and mean exactly the same thing. The
reed consists of two parallel pieces of wood, set a few inches apart,
and they are of any given length, as a yard, a yard and a quarter, &c.
The division of the yard being into halves, quarters, eighths, and
sixteenths; the breadth of a web is generally expressed by a vulgar
fraction, as 1/4, 4/4, 5/4, 6/4; and the subdivisions by the eighths or
sixteenths, or _nails_, as they are usually called, as 7/8, 9/8, 11/8,
&c., or 13/16, 15/16, 19/16, &c. In Scotland, the splits of cane which
pass between the longitudinal pieces or ribs of the reed, are expressed
by hundreds, porters, and splits. The porter is 20 splits, or 1/5th of
an hundred.

In Lancashire and Cheshire a different mode is adopted, both as to the
measure and divisions of the reed. The Manchester and Bolton reeds are
counted by the number of splits, or, as they are there called, dents,
contained in 24-1/4 inches of the reed. These dents, instead of being
arranged in hundreds, porters, and splits, as in Scotland, are
calculated by what is there termed _hares_ or _bears_, each containing
20 dents, or the same number as the porter in the Scotch reeds. The
Cheshire or Stockport reeds, again, receive their designation from the
number of ends or threads contained in one inch, two ends being allowed
for every _dent_, that being the almost universal number in every
species and description of plain cloth, according to the modern practice
of weaving, and also for a great proportion of fanciful articles.

The number of threads in the warp of a web is generally ascertained with
considerable precision by means of a small magnifying glass, fitted into
a socket of brass, under which is drilled a small round hole in the
bottom plate of the standard. The number of threads visible in this
perforation, ascertains the number of threads in the standard measure of
the reed. Those used in Scotland have sometimes four perforations, over
any one of which the glass may be shifted. The first perforation is 1/4
of an inch in diameter, and is therefore well adapted to the Stockport
mode of counting; that is to say, for ascertaining the number of ends or
threads per inch; the second is adapted for the Holland reed, being
1/200th part of 40 inches; the third is 1/700th of 37 inches, and is
adapted for the now almost universal construction of Scotch reeds; and
the fourth, being 1/200th of 34 inches, is intended for the French
cambrics. Every thread appearing in these respective measures, of course
represents 200 threads, or 100 splits, in the standard breadth; and thus
the quality of the fabric may be ascertained with considerable
precision, even after the cloth has undergone repeated wettings, either
at the bleaching-ground or dye-work. By counting the other way, the
proportion which the woof bears to the warp is also known, and this
forms the chief use of the glass to the manufacturer and operative
weaver, both of whom are previously acquainted with the exact measure of
the reed.

Comparative TABLE of 37-inch reeds, being the standard used throughout
Europe, for linens, with the Lancashire and Cheshire reeds, and the
foreign reeds used for holland and cambric.

  +-------+-----------+---------+--------------+---------------+
  |Scotch.|Lancashire.|Cheshire.|Dutch holland.|French cambric.|
  +-------+-----------+---------+--------------+---------------+
  |  600  |    20     |    34   |      550     |      653      |
  |  700  |    24     |    38   |      650     |      761      |
  |  800  |    26     |    44   |      740     |      870      |
  |  900  |    30     |    50   |      832     |      979      |
  | 1000  |    34     |    54   |      925     |     1089      |
  | 1100  |    36     |    60   |     1014     |     1197      |
  | 1200  |    40     |    64   |     1110     |     1300      |
  | 1300  |    42     |    70   |     1202     |     1414      |
  | 1400  |    46     |    76   |     1295     |     1464      |
  | 1500  |    50     |    80   |     1387     |     1602      |
  | 1600  |    52     |    86   |     1480     |     1752      |
  | 1700  |    56     |    92   |     1571     |     1820      |
  | 1800  |    58     |    96   |     1665     |     1958      |
  | 1900  |    62     |   104   |     1757     |     2067      |
  | 2000  |    66     |   110   |     1850     |     2176      |
  +-------+-----------+---------+--------------+---------------+

In the above table, the 37-inch is placed first. It is called Scotch,
not because it either originated or is exclusively used in that country.
It is the general linen reed of all Europe; but in Scotland it has also
been adopted as the regulator of her cotton manufactures.


REFINING OF GOLD AND SILVER; called also _Parting_. (_Affinage
d’argent_, _Départ_, Fr.; _Scheidung in die quart_, Germ.) For several
uses in the arts, these precious metals are required in an absolutely
pure state, in which alone they possess their malleability and peculiar
properties in the most eminent degree. Thus, for example, neither gold
nor silver leaf can be made of the requisite fineness, if the metals
contain the smallest portion of copper alloy. Till within these ten or
twelve years, the parting of silver from gold was effected every where
by nitric acid; it is still done so in all the establishments of this
country, except the Royal Mint; and in the small refining-houses abroad.
The following apparatus may be advantageously employed in this
operation. It will serve the double purpose of manufacturing nitric acid
of the utmost purity, and of separating silver from gold by its means.

[Illustration: 931]

1. _On procuring nitric acid for parting._--_a_ is a platinum retort or
alembic; _b_ is its capital, terminating above in a tubulure, to which a
kneed tube of platinum, about 2 feet long, is adapted; _c_ is the
tubulure of the retort, for supplying acid during the process, and for
inspecting its progress. It is furnished with a lid ground air-tight,
which may be secured in its place by a weight. _e_ is a stoneware pipe,
about two inches diameter, and several feet long, according to the
locality in which the operation is to be carried on. It is made in
lengths fitted to one another, and secured at the joints with loam-lute.
The one bend of this earthenware hard salt-glazed pipe is adapted to
receive the platinum tube, and the other bend is inserted into a
tubulure in the top of the stoneware drum _f_. The opening _l_, _l_, in
the middle of the top of _f_, is for inspecting the progress of the
condensation of acid; and the third tubulure terminates in a prolonged
pipe _i_, _i_, consisting of several pieces, each of which enters from
above conically into the one below. The joinings of the upper pieces
need not be tightly luted, as it is desirable that some atmospherical
oxygen should enter, to convert the relatively light nitrous gas into
nitrous or nitric acid vapour, which when supplied with moisture will
condense and fall down in a liquid state. To supply this moisture in the
most diffusive form, the upright stoneware pipes _i_, _i_, _l_, _l_, (at
least 3 inches diameter, and 12 feet high,) should be obstructed
partially with flint nodules, or with siliceous pebbles; and water
should be allowed to trickle upon the top pebble from a cistern placed
above. Care must be taken to let the water drop so slowly as merely to
preserve the pebbles in a state of humidity. _h_ is a stopcock, of glass
or stoneware, for drawing off the acid from the cistern _f_. _k_ is a
section of a small air-furnace, covered in at top with an iron ring, on
which the flat iron ring of the platinum frame rests.

_g_, _g_, is a tub in which the stoneware cistern stands, surrounded
with water, kept constantly as cold as possible by passing a stream
through it; the spring water entering by a pipe that dips near to the
bottom, and the hot water escaping at the upper edge.

With the above apparatus, the manufacture of pure nitric acid is
comparatively easy and economical. Into the alembic _a_, 100 pounds (or
thereby) of pure nitre, coarsely bruised if the crystals be large, are
to be put; the capital is then to be adapted, and the platinum tube (the
only movable one) luted into its place. Twenty pounds of strong
sulphuric acid are now to be introduced by the tubulure _c_, and then
its lid must be put on. No heat must yet be applied to the alembic. In
about an hour, another ten pounds of acid may be poured in, and so every
hour, till 60 pounds of acid have been added. A few hours after the
affusion of the last portion of acid, a slight fire may be kindled in
the furnace _k_.

By judicious regulation of the heat, the whole acid may be drawn off in
24 hours; its final expulsion being aided by the dexterous introduction
of a quart or two of boiling water, in small successive portions, by the
tubulure _c_, whose lid must be instantly shut after every inspersion.
The most convenient strength of acid for the parting process, is when
its specific gravity is about 1·320, or when a vessel that contains 16
ounces of pure water, will contain 21-1/8 of the aquafortis. To this
strength it should be brought very exactly by the aid of a hydrometer.

Its purity is easily ascertained by letting fall into it a few drops of
solution of silver; and if no perceptible milkiness ensues, it may be
accounted good. Should a white cloud appear, a few particles of silver
may be introduced, to separate whatever muriatic acid may be present, in
the form of chloride of silver. Though a minute quantity of sulphuric
acid should exist in the nitric, it will be of no consequence in the
operation of parting.

2. _On parting by the nitric acid, called by the Mexicans, “Il
apartado.”_--The principle on which this process is founded, is the fact
of silver being soluble in nitric acid, while gold is insoluble in that
menstruum. If the proportion of gold to that of silver be greater than
one to two, then the particles of the former metal so protect or envelop
those of the latter, that the nitric acid, even at a boiling heat,
remains quite inactive on the alloy. It is indispensable, therefore,
that the weight of the silver be at least double that of the gold. 100
pounds of silver take 38 pounds of nitric acid, of specific gravity
1·320, for oxidizement, and 111 for solution of the oxide; being
together 149; but the refiner often consumes, in acid of the above
strength, more than double the weight of silver, which shows great
waste, owing to the imperfect means of condensation employed for
recovering the vapours of the boiling and very volatile acid.

By the apparatus above delineated, the 38 pounds of acid expended in
oxidizing the silver, become nitrous gas in the first place, and are
afterwards reconverted in a great measure into nitric acid by absorption
of atmospherical oxygen; so that not one-fifth need be lost, under good
management. As the acid must be boiled on the granulated _garble_, or
alloy, to effect the solution of the silver, by proper arrangements the
vapours may be entirely condensed, and nearly the whole acid be
recovered, except the 111 parts indispensable to constitute nitrate of
silver. Hence, with economical management, 120 pounds of such acid may
be assigned as adequate to dissolve 100 of silver associated with 50 of
gold.

It must here be particularly observed, that 100 pounds of copper require
130 pounds of the above acid for oxidizement; and 390 for solution of
the oxide; being 520 pounds in whole, of which less than 1/4 part could
be recovered by the above apparatus. It is therefore manifest that it is
desirable to employ silver pretty well freed from copper by a previous
process; and always, if practicable, a silver containing some gold.

These data being assumed as the bases of the parting operation, 60
pounds of gold and silver alloy or _garble_ finely granulated,
containing not less than 40 pounds of silver, are to be introduced into
the ten-gallon alembic of platinum, _fig._ 931., and 80 pounds of nitric
acid, of 1·320, is to be poured over the alloy; a quantity which will
measure 6 gallons imperial. As for the bulk of the alloy, it is
considerably less than half a gallon. Abundance of space therefore
remains in the alembic for effervescence and ebullition, provided the
fire be rightly tempered.

By the extent of stoneware conducting pipe _e_, which should not be less
than 40 feet, by the dimensions and coldness of the cistern _f_, and by
the regenerating influence of the vertical aerial pipe filled with moist
pebbles _i_, _i_, it is clear, that out of the 80 pounds of nitric acid,
specific gravity 1·320, introduced at first, from 20 to 30 will be
recovered.

Whenever the effervescence and disengagement of nitrous red fumes no
longer appear on opening the orifice _c_, the fire must be removed, and
the vessel may be cooled by the application of moist cloths. The alembic
may be then disengaged from the platinum tube, and lifted out of its
seat. Its liquid contents must be cautiously decanted off, through the
orifice _c_, into a tub nearly filled with soft water. On the heavy
pulverulent gold which remains in the vessel, some more acid should be
boiled, to carry off any residuary silver. This metallic powder, after
being well washed with water, is to be dried, fused along with a little
nitre or borax, and cast into ingots.

Plates of copper being immersed in the nitric solution contained in
wooden or stoneware cisterns, will throw metallic silver down, while a
solution of nitrate of copper, called blue water, will float above. The
pasty silver precipitate is to be freed from the nitrate of copper,
first, by washing with soft water, and next, by strong hydraulic
pressure in cast-iron cylinders. The condensed mass, when now melted in
a crucible along with a little nitre and borax, is fine silver.

The above apparatus has the further advantage of enabling the operator
to recover a great portion of his nitric acid, by evaporating the blue
water to a state approaching to dryness, with the orifices at _c_, and
at the top of the capital, open. In the progress of this evaporation,
nothing but aqueous vapour escapes. Whenever the whole liquid is
dissipated, the pipe _d_ is to be re-adjusted, and the lid applied
closely to _c_. The heat being now continued, and gradually increased,
the _whole_ nitric acid will be expelled from the copper oxide, which
will remain in a black mass at the bottom of the alembic. The
contrivance for letting water trickle upon the pebbles, must be
carefully kept in play, otherwise much of the evolved acid would be
dissipated in nitrous fumes. With due attention to the regenerative
plan, a great part of the acid may be recovered, at no expense but that
of a little fuel.

The black oxide of copper thus obtained, is an economical form of
employing that metal for the production of the sulphate; 100 pounds of
it, with 122-1/2 of sulphuric acid diluted with water, produce 312-1/2
pounds of crystallized sulphate of copper. A leaden boiler is best
adapted for that operation. 100 pounds of silver are precipitable from
its solution in nitric acid, by 29 of copper. If more be needed, it is a
proof that a wasteful excess of acid has existed in the solution.

In parting by nitric acid, the gold generally retains a little silver;
as is proved by the cloud of chloride of silver which it affords, at the
end of some hours, when dissolved in aqua regia. And on the other hand,
the silver retains a little gold. These facts induced M. Dizé, when he
was inspector of the French mint, to adopt some other process, which
would give more accurate analytical results; and after numerous
experiments, he ascertained that sulphuric acid presented great
advantages in this point of view, since with it he succeeded in
detecting, in silver, quantities of gold which had eluded the other plan
of parting. The suggestion of M. Dizé has been since universally adopted
in France. M. Costell, about nine or ten years ago, erected in
Pomeroy-street, Old Kent-road, a laboratory upon the French plan, for
parting by sulphuric acid; but he was not successful in his enterprise;
and since he relinquished the business, Mr. Matheson introduced the same
system into our Royal Mint, under the management of M. Costell’s French
operatives. In the Parisian refineries, gold, to the amount of
one-thousandth part of the weight, has been extracted from all the
silver which had been previously parted by the nitric acid process;
being 3500 francs in value upon every thousand kilogrammes of silver.

I shall give first a general outline of the method of parting by
sulphuric acid, and then describe its details as I have lately seen them
executed upon a magnificent scale in an establishment near Paris.

The most suitable alloy for refining gold, by the sulphuric-acid
process, is the compound of gold, silver, and copper, having a standard
quality, by the cupel, of from 900 to 950 millièmes, and containing
one-fifth of its weight of gold. The best proportions of the three
metals are the following:--silver, 725; gold, 200; copper, 75; = 1000.
It has been found that alloys which contain more copper, afford
solutions that hold some anhydrous sulphate of that metal in solution,
which prevents the gold from being readily separated; and that alloys
containing more gold, are not acted on easily by the sulphuric acid. The
refiner ought, therefore, when at all convenient, to reduce the alloys
that he has to treat, to the above-stated proportions. He may effect
this purpose either by fusing the coarser alloys with nitre in a
crucible, or by adding finer alloy, or even fine silver, or finally, by
subjecting the coarser alloys to a previous cupellation with lead on
the great scale. As to gold or silver bullion, which contains lead and
other easily oxidizable metals besides copper, the refiner ought always
to avoid treating them by sulphuric acid; and should separate, first of
all, these foreign metals by the agency of nitre, if they exist in
minute quantity; but if in larger, he should have recourse to the cupel.
Great advantage will therefore be derived from the judicious preparation
of the alloy to be refined.

For an alloy of the above description, the principal Parisian refiners
are in the habit of employing thrice its weight of sulphuric acid, in
order to obtain a clear solution of sulphate of silver, which does not
too suddenly concrete on cooling, so as to obstruct its discharge from
the alembic by decantation. A small increase in the quantity of copper,
calls for a considerable increase in the quantity of acid.

Generally speaking, one-half of the sulphuric acid strictly required for
converting the silver and copper into sulphates, is decomposed into
sulphurous acid, which is lost to the manufacturer, unless he has
recourse to the agency of nitrous acid.

The process for silver containing but little gold, consists of five
different operations.

1. Upon several furnaces, one foot in diameter, egg-shaped alembics of
platinum are mounted, into each of which are put 3 kilogrammes (8 lbs.
troy) of the granulated silver, containing a few grains of gold per
pound, and 6 kilogrammes of concentrated sulphuric acid. The alembics
are covered with conical capitals, ending in bent tubes, which conduct
the acid vapours into lead pipes of condensation; and the furnaces are
erected under a proper hood. As the cold acid is inoperative, it must be
set a boiling, at which temperature it gives up one atom of its oxygen
to the metal, and is transformed into sulphurous acid, which escapes in
a gaseous state. Some of the undecomposed sulphuric acid immediately
combines with the oxide into a sulphate, which subsides, in the state of
a crystalline powder, to the bottom of the vessel. The solution goes on
vigorously, with a copious disengagement of sulphurous acid gas, only
during the two or three first hours; after which it proceeds slowly, and
is not completed till after a digestion of nearly twelve hours more.
During the ebullition a considerable quantity of sulphuric acid vapour
escapes along with the sulphurous acid gas; the former of which is
readily condensed in a large leaden receiver immersed in a cistern of
cold water, if need be. It has been proposed to condense the sulphurous
acid, by leading it over extensive surfaces of lime-pap, as in the
coal-gas purifiers.

2. When the whole silver has been converted into sulphate, this is to be
emptied out of the alembic into water contained in a round-bottomed
receiver lined with lead, and diluted till the density of the solution
marks from 15° to 20° Baumé. The small portion of gold, in the form of a
brown powder, which remains undissolved, having been allowed to settle
to the bottom, the supernatant solution of silver is to be decanted
carefully off into a leaden cistern, and the powder being repeatedly
edulcorated with water, the washings are to be added to it. The silver
is now to be precipitated by plunging plates of copper in the solution,
and the magma which falls is to be well washed, and freed from the
residuary particles of sulphate of copper by powerful compression.

3. The silver, precipitated and dried as above described, is melted in a
crucible, and cast into an ingot.

4. The gold powder is also dried and cast into an ingot, a little nitre
being added in the fusion, to oxidize and separate any minute particles
of copper that may perchance have been protected from the solvent action
of the acid.

5. As the sulphate of copper is of considerable value, its solution is
to be neutralized, evaporated in leaden pans to a proper strength, and
set aside to crystallize in leaden cisterns. The farmers throughout
France consume an immense quantity of this salt. They sprinkle a weak
solution of it (at 2° or 3° Baumé) over their grain before sowing it, in
order to protect it against the ravages of birds and insects.

The pure gold, at the instant of its separation from the alloy by the
action of sulphuric acid, being in a very fine powder, and lying in
close contact with the platinum, under the influence of a boiling
menstruum, which brightens the surfaces of the two metals, and raises
their temperature to fully the 600th degree of Fahrenheit’s scale, tends
to become partially soldered to the platinum, and may thus progressively
thicken the bottom of the still. The importance of preserving this
vessel entire, and of economizing the fuel requisite to heat its
contents, induces the refiner to detach the crust of gold from time to
time, by passing over the bottom of the still, in small quantities, a
dilute nitro-muriatic acid, which acts readily on gold, but not on
platinum. But as this operation is a very delicate one, it must be
conducted with great circumspection. The danger of such adhering
deposits is much increased by using too high a heat, and too small a
body of acid, relatively to the metals dissolved. Hence it is
advantageous to employ alembics of large size. Should any lead or tin
get into the platinum still, while the hot acid is in it, the precious
vessel would be speedily destroyed; an accident which has not
unfrequently happened. Each operation may be conveniently finished in
twelve hours; so that each alembic may refine with ease 160 marcs
daily. Some persons work more rapidly, but such haste is hazardous.

The Parisian refiners restore to the owners the whole of the gold and
silver contained in the ingots, reserving to themselves the copper which
formed the alloy, and charging only the sum of 5-1/2 francs per
kilogramme (2·68 lbs. troy) for the expense of the parting of the
metals.

If they are employed to refine an ingot of silver containing less than
one-tenth of gold, they retain for themselves a two-thousandth part of
the gold, and all the copper, existing in the alloy; return all the rest
of the gold, with the whole of the silver, in the ingot; and give,
besides, to the owners a _premium_ or _bonus_, which amounted lately to
3/4 of a franc on the kilogramme of metal. Should the owner desire to
have the whole of the gold and silver contained in his ingot, the
refiner then demands from him 2 francs and 68 centimes per kilogramme,
retaining the copper of the alloy. As to silver ingots of low standard,
the perfection of the refining processes is such, that the mere copper
contained in them pays all the costs; for in this case, the refiner
restores to the proprietor of the ingot as much fine silver as the assay
indicated to exist in the ingot, contenting himself with the copper of
the alloy. See _infrà_.

The chemical works of M. Poizat, called _affinage d’argent_, on the bank
of the _canal de l’Ourcq_, in the vicinity of Paris, are undoubtedly the
most spacious and best arranged for refining the precious metals, which
exist in the world. On being introduced to this gentleman, by my friend
and companion M. Clement-Desormes, he immediately expressed his
readiness to conduct me through his _fabrique_, politely alluding to the
French translation of my Dictionary of Chemistry, which lay upon the
desk of his _bureau_. The principal room is 240 feet long, 40 feet wide,
and about 30 feet high. A lofty chimney rises up through the middle of
the apartment, and another at each of its ends. The one space, 120 feet
long, to the right of the central chimney, is allotted to the processes
of dissolving the silver, and parting the gold; the other, to the left,
to the evaporation and crystallization of the sulphate of copper, and
the concentration of the recovered sulphuric acid.

M. Poizat melts his great masses of silver in pots made of malleable
iron, capable of holding several cwts. each; and granulates it by
pouring it into water contained in large iron pans. The granulated
silver is dried with heat, and carried into a well lighted office
enclosed by glazed casements, to be weighed, registered, and divided
into determinate portions. Each of these is put into a cast-iron pot, of
a flattened hemispherical shape, about 2 feet in diameter, covered with
an iron lid, made in halves, and hinged together in the middle line.
From the top of the fixed lid a bent pipe issues, and proceeds downwards
into an oblong leaden chest sunk beneath the floor. Four of the above
cast-iron pots stand in a line across the room, divided into two ranges,
with an intervening space for passing between them. The bottoms of the
pots are directly heated by the flame, one fire serving for two pots.
Two parts of concentrated sulphuric acid by weight are poured upon every
part of granulated silver, and kept gently boiling till the whole silver
be converted into a pasty sulphate.

From the underground leaden chests, a leaden pipe, 4 inches in diameter,
rises vertically, and enters the side of a leaden chamber, which is
supported upon strong cross-beams or rafters, a little way beneath the
roof of the apartment. This chamber, which is 30 feet long, 10 feet
wide, and 6 feet high, is intended to condense the sulphuric acid
vapours, along with some of the sulphurous acid; that of the latter
being promoted by the admission of nitrous gas and air, which convert it
into sulphuric acid. From the further end of this chamber, a large
square leaden pipe returns with a slight slope towards the middle of the
room, and terminates at the right-hand side of the central chimney, in a
small leaden chest, for receiving the drops of acid which are condensed
in the pipe. From that chest a pipe issues, to discharge into the high
central chimney the incondensable gases, and also to maintain a constant
draught through the whole series of leaden chambers back to the
cast-iron hemispherical pots.

Besides the above cast-iron pots, destined to dissolve only the coarse
cupreous silver, containing a few grains of gold per pound, there are,
in the centre of the apartment, at the right-hand side of the chimney, 6
alembics of platinum, in which the rich alloys of gold and silver are
treated in the process of refining gold.

The pasty sulphate of silver obtained in the iron pots, is transferred
by cast-iron ladles with long handles into large leaden cisterns,
adjoining the pots, and there diluted with a little water to the density
of 36° Baumé. Into this liquor, steam is admitted through a series of
upright leaden pipes arranged along the side of the cistern, which
speedily causes ebullition, and dilutes the solution eventually to the
22d degree of Baumé. In this state, the liquid supersulphate is run off
by leaden syphons into large oblong leaden cisterns, rounded at the
bottom; and is there exposed to the action of ribands of copper, like
thin wood shavings. The metallic silver precipitates in a pasty form;
and the supernatant sulphate of copper is then run off into a cistern,
upon a somewhat lower level, where it is left to settle and become
clear.

The precipitate of silver, called by the English, water-silver, and by
the French, _chaux d’argent_, is drained, then strongly squeezed in a
square box of cast iron, by the action of a hydraulic press; in which 60
pounds of silver are operated upon at once.

The silver lumps are dried, melted in black lead crucibles, in a furnace
built near the silver end of the room, where the superintendent sits in
his _bureau_--a closet enclosed by glazed casements, like a green-house.
The whole course of the operations is so planned, that they are made to
commence near the centre with the mixed metals, and progressively
approach towards the office end of the apartment as the parting
processes advance. Here the raw material, after being granulated and
weighed, was given out, and here the pure gold and silver are finally
eliminated in a separate state.

In the other half of the hall, the solutions of sulphate of copper are
evaporated in large shallow leaden pans, placed over a range of
furnaces; from which, at the proper degree of concentration, they are
run off by syphons into crystallizing pans of the same metal. From the
mother-waters, duly evaporated, a second crop of crystals is obtained;
and also a third, the last being anhydrous, from the great affinity for
water possessed by the strong sulphuric acid with which they are now
surrounded. The acid in this way parts with almost the whole of the
cupreous oxide, and is then transferred into a large alembic of platinum
(value 1000_l._), to be rendered fit, by re-concentration, for acting
upon fresh portions of granulated silver. The capital of that alembic is
connected with a leaden-worm, which traverses an oblong vessel, through
which a stream of cold water flows.

The crystallized sulphate of copper fetched, two years ago, 30_l._ a
ton. It is almost all sold to the grocers in the towns of the
agricultural districts of France. In the above establishment of M.
Poizat, silver to the value of 10,000_l._ can be operated upon daily.

There is a steam engine of 6-horse power placed in a small glazed
chamber at one side of the parting hall, which serves to work all his
leaden pumps for lifting the dilute sulphuric acid and acidulous
solutions of copper into their appropriate cisterns of concentration, as
also to grind his old crucibles, and drive his amalgamation mill,
consisting of a pair of vertical round-edged wheels, working upon one
shaft, in a groove formed round a central hemisphere--of cast iron.
After the mercury has dissolved out of the ground crucibles all the
particles of silver which it can find, the residuary earthy matter is
sold to the _sweep-washers_. The floor of the hall around the alembics,
pots, and cisterns, is covered with an iron grating, made of bars having
one of their angles uppermost, to act as scrapers upon the shoes of the
operatives. The dust collects in a vacant space left beneath the
grating, whence it is taken to the amalgamation mill. The processes are
so well arranged and conducted by M. Poizat, that he can execute as much
business in his establishment with 10 workmen as is elsewhere done with
from 40 to 50; and with less than 3 grains of gold, in one Paris pound
or 7561 grains of silver, he can defray the whole expenses of the
parting or refining.

Since 26 parts of copper afford 100 of the crystallized sulphate, the
tenth of copper present in the dollars, and most foreign coins, will
yield nearly four times its weight of blue vitriol; a subsidiary product
of considerable value to the refiner.

The works of M. Poizat are so judiciously fitted up as to be quite
salubrious, and have not those “very mischievous effects upon the
trachea,” which Mr. Matheson states as being common in his refinery
works in the Royal Mint.[48] But, in fact, as refining by sulphuric acid
is always a nuisance to a neighbourhood, it is not suffered in the
_Monnaie Royale_ of Paris; but is best and most economically performed
by private enterprise and fair competition, which is impossible in
London, on account of the anomalous privilege, worth at least 2000_l._ a
year, possessed by Mr. Matheson, who works most extensively for private
profit on a public plant, fitted up with a lofty chimney, platinum
vessels to the value of 3000_l._, and other apparatus, at the cost of
the government. His charge to the crown for refining gold per lb. troy,
is 6_s._ 6_d._; that of the refiners in London, who are obliged, for
fear of prosecution, to employ the more expensive, but more condensable,
nitric acid, is only 4_s._ That of the Parisian refiners is regulated as
follows. For the dealers in the precious metals:--

  [48] Report of Committee of House of Commons on the Mint, in 1837, p.
  91.

For gold bullion containing silver, and more than 100/1000 of gold, 6
fr. 12 c. per kilogramme, = 2 fr. 29 c. per lb. troy.

For silver bullion, containing from 1/1000 to 100/1000 of gold (called
_dorés_), 3 fr. 27 c. per kilogramme, = 1 fr. 22 c. per lb. troy.

For the _Monnaie_, the charges are--

For gold refined by sulphuric acid, when alloyed with copper only, from
898/1000 to 1/1000, 5 fr. per kilogramme, = 1 fr. 86 c. per lb. troy.

For gold alloyed with copper and silver, whatever be the quantity of
silver, 5 fr. 75 c. per kilogramme, = 2 fr. 12 c. per lb. troy.

There are about ten bullion refiners by sulphuric acid in the environs
of Paris; two of whom, M. Poizat St. André, and M. Chauvière, are by far
the most considerable; the former working about 300 kilogrammes (= 804
lbs. troy) daily, and the latter about two-thirds of that quantity. In
former times, when competition was open in London, Messrs. Browne and
Brinde were wont to treat 6 cwts. of silver, or 9 cwts. of gold alloy,
daily, for several months in succession.

The result of _free trade_ in refining bullion at Paris is, that the
silver bars imported into London from South America, &c., are mostly
sent off to Paris to be stripped of the few grains of gold which they
may contain, and are then brought back to be sold here. Three grains of
gold in one Paris lb. of silver, pay the refiners there for taking them
out. What a disgrace is thus brought upon our manufacturing industry and
skill, by the monopoly charges in refining and assaying granted to two
individuals in our Royal Mint.

Mr. Bingley’s charges for assaying at the Royal Mint in London, are--

For an assay of gold, 4_s._; for a parting assay of gold and silver,
6_s._; for a silver assay, 2_s._ 6_d._--charges which absorb the profits
of many a transaction.

The charges at the Royal Mint of Paris, for assays made under the
following distinguished chemical _savants_--Darcet, _Directeur_; Bréant,
_Verificateur_; Chevillot and Pelouze, _Essayeurs_; are--

  For an assay of gold, or _doré_, (a parting assay,) 3 francs.
       --       silver           --             --    0. 80 c. = 8_d._
                                                              English.

M. Gay Lussac is the assayer of the _Bureau de Garantie_ at the _Monnaie
Royale_, an office which corresponds to the Goldsmiths’ Hall at London.
The silver assays in all the official establishments of Europe, except
the two in London, are made by the _humid_ method, and are free from
those errors and blunders which daily annoy and despoil the British
bullion merchant, who is compelled by the Mint and Bank of England to
buy and sell by the _cupellation_ assay of Mr. Bingley. See ASSAY and
SILVER.


REFRIGERATION OF WORTS, &c. In August, 1826, Mr. Yandall obtained a
patent for an apparatus designed for cooling worts and other hot fluids,
without exposing them to evaporation. Utensils employed for this
purpose, are generally called refrigerators, and are so constructed,
that a quantity of cold water shall be brought in contact with the
vessel which contains the heated fluid. But in every construction of
refrigerator heretofore used, the quantity of cold water necessarily
employed in the operation, greatly exceeded the quantity of the fluid
cooled, which, in some situations, where water cannot be readily
obtained, was a serious impediment and objection to the use of such
apparatus.

The inventor has contrived a mode of constructing a refrigerator, so
that any quantity of wort or other hot fluid may be cooled by an equal
quantity of cool water; the process being performed with great
expedition, simply by passing the two fluids through very narrow
passages, in opposite directions, the result of which is, that the cold
liquor imbibes the heat from the wort, or other fluid, and the
temperature of the hot fluid is reduced in the same ratio.

[Illustration: 932 933 934]

_Figs._ 932, 933, and 934. represent different forms in which the
apparatus is proposed to be made. The two first have zigzag passages;
the third, channels running in convolute curves. These channels or
passages are of very small capacity in thickness, but of great length,
and of any breadth that may be required, according to the quantity of
fluid intended to be cooled or heated.

_Fig._ 935. is the section of a portion of the apparatus shown at
_figs._ 932. and 933. upon an enlarged scale; it is made by connecting
three sheets of copper or any other thin metallic plates together,
leaving parallel spaces between each plate for the passage of the
fluids, represented by the black lines.

These spaces are formed by occasionally introducing between the plates
thin straps, ribs, or portions of metal, by which means very thin
channels are produced, and through these channels the fluids are
intended to be passed, the cold liquor running in one direction, and the
hot in the reverse direction.

Supposing that the passages for the fluids are each one-eighth of an
inch thick, then the entire length for the run of the fluid should be
about 80 feet, the breadth of the apparatus being made according to the
quantity of fluid intended to be passed through it in a given time. If
the channels are made a quarter of an inch thick, then their length
should be extended to 160 feet; and any other dimensions in similar
proportions: but a larger channel than one quarter of an inch, the
patentee considers would be objectionable. It is, however, to be
observed, that the length here recommended, is under the consideration,
that the fluids are driven through the apparatus by some degree of
hydrostatic pressure from a head in the delivery-vats above; but if the
fluids flow without pressure, then the lengths of the passages need not
be quite so great.

[Illustration: 935]

In the apparatus constructed as shown in perspective at _fig._ 932., and
further developed by the section, _fig._ 935., cold water is to be
introduced at the funnel _a_, whence it passes down the pipe _b_, and
through a long slit or opening in the side of the pipe, into the passage
_c_, _c_ (see _fig._ 935.), between the plates, where it flows in a
horizontal direction through the channel towards the discharge-pipe _d_.
When such a quantity of cold water has passed through the funnel _a_, as
shall have filled the channel _c_, _c_, up to the level of the top of
the apparatus, the cock _e_ being shut, then the hot wort or liquor
intended to be cooled, may be introduced at the funnel _f_, and which,
descending in the pipe _g_, passes in a similar manner to the former,
through a long slit or opening in the side of the pipe _g_, into the
extended passage _h_, _h_ (see _fig._ 935.), and from thence proceeds
horizontally into the discharge-pipe _i_.

The two cocks _e_ and _k_, being now opened, the wort or other liquor is
drawn off, or otherwise conducted away through the cock _k_, and the
water through _e_. If the apertures of the two cocks _e_ and _k_, are
equal, and the channels equal also, it follows that the same quantity of
wort, &c., will flow through the channel _h_, _h_, _h_, in a given time,
as of water through the channel _c_, _c_; and by the hot fluid passing
through the apertures in contact with the side of the channel which
contains the cold fluid, the heat becomes abstracted from the former,
and communicated to the latter; and as the hot fluid enters the
apparatus at that part which is in immediate contact with the part where
the cooling fluid is discharged, and the cold fluid enters the apparatus
at that part where the wort is discharged, the consequence is, that the
wort or other hot liquor becomes cooled down towards its exit-pipe
nearly to the temperature of cold water; and the temperature of the
water, at the reverse end of the apparatus, becomes raised nearly to
that of the boiling wort.

It only remains to observe, that by partially closing either of the
exit-cocks, the quantity of heat abstracted from one fluid, and
communicated to the other, may be regulated; for instance, if the cock
_e_ of the water-passage be partially closed, so as to diminish the
quantity of cold water passed through the apparatus, the wort or other
hot fluid conducted through the other passages will be discharged at a
higher temperature, which in some cases will be desirable, when the
refrigerated liquor is to be fermented.

_Fig._ 933. exhibits an apparatus precisely similar to the foregoing,
but different in its position; for instance, the zigzag channels are
made in obliquely descending planes. _a_ is the funnel for the hot
liquor, whence it descends through the pipe _d_ into the channel _c_,
_c_ (see _fig._ 935.), and ultimately is discharged through the pipe
_b_, at the cock _e_. The cold water being introduced into the funnel
_f_, and passing down the pipe _i_, enters the zigzag channel _h_, _h_,
and, rising through the apparatus, runs off by the pipe _g_, and is
discharged at the cock below.

The passages of this apparatus for heating and cooling fluids, may be
bent into various contorted figures; one form found particularly
convenient under some applications, is that represented at _fig._ 934.,
which is contained in a cylindrical case. The passages here run in
convolute curves, the one winding in a spiral to the centre, the other
receding from the centre.

The wort or other hot liquor intended to be cooled, is to be introduced
at the funnel _a_, and passing down the pipe _b_, is delivered into the
open passage _c_, which winds round to the central chamber _d_, and is
thence discharged through the pipe _e_, at the cock _f_. The cold water
enters the apparatus at the funnel _g_, and proceeding down the pipe
_h_, enters the closed channel _i_, and after traversing round through
the apparatus, is in like manner discharged through the pipe _k_, at the
cock _l_. Or the hot liquor may be passed through the closed channel,
and the cold through the open one; or these chambers may be both of them
open at top, and the apparatus covered by a lid when at work, the
principal design of which is to afford the convenience of cleaning them
more readily than could be done if they were closed; or they may be both
closed.

A similar ingenious apparatus for cooling brewers’ worts, or wash for
distillers, and also for condensing spirits in place of the ordinary
worm tub, is called by the inventor, Mr. Wheeler, an Archimedes
condenser, or refrigerator, the peculiar novelty of which consists in
forming the chambers for the passage of the fluids in spiral channels,
winding round a central tube, through which spiral channels the hot and
cold fluids are to be passed in opposite directions.

[Illustration: 936 937 938]

_Fig._ 936. represents the external appearance of the refrigerator,
enclosed in a cylindrical case; _fig._ 937., the same, one-half of the
case being removed to show the form of the apparatus within; and _fig._
938., a section cut through the middle of the apparatus perpendicularly,
for the purpose of displaying the internal figure of the spiral
channels.

The apparatus is proposed to be made of sheet copper, tinned on its
surface, and is formed by cutting circular pieces of thin copper, or
segments of circles, and connecting them together by rivets, solder, or
by any other convenient means, as coppersmiths usually do; these
circular pieces of copper being united to one another, in the way of a
spiral or screw, form the chambers through which the fluids are to pass
within, in an ascending or descending inclined plane.

In _figs._ 937. and 938., _a_, _a_, is the central tube or standard (of
any diameter that may be found convenient), round which the spiral
chambers are to be formed; _b_, _b_, are the sides of the outer case, to
which the edges of the spiral fit closely, but need not be attached;
_c_, _c_, are two of the circular plates of copper, connected together
by rivets at the edges, in the manner shown, or by any other suitable
means; _d_, is the chamber, formed by the two sheets of copper, and
which is carried round from top to bottom in a spiral or circular
inclined plane, by a succession of circular plates connected to each
other.

The hot fluid is admitted into the spiral chamber _d_, through a trumpet
or wide-mouthed tube _e_, at top, and is discharged at bottom by an
aperture and cock _f_. The cold water which is to be employed as the
cooling material, is to be introduced through the pipe _g_, in the
centre, from whence discharging itself by a hole at bottom, the cold
water occupies the interior of the cylindrical case _b_, and rises in
the spiral passage _h_, between the coils of the chamber, until it
ascends to the top of the vessel, and then it flows away by a spout _i_,
seen in _fig._ 936.

It will be perceived that the hot fluid enters the apparatus at top, and
the cold fluid at bottom, passing each other, by means of which an
interchange of temperatures takes place through the plates of copper,
the cooling fluid passing off at top in a heated state, by means of the
caloric which it has abstracted from the hot fluid; and the hot fluid
passing off through the pipe and cock at bottom, in a very reduced state
of temperature, by reason of the caloric which it held having been given
out to the cooling fluid.

[Illustration: 939 940]

_Fig._ 939. is a side view and section of Wagenmann’s apparatus for
cooling worts; _fig._ 940., a view from above. The preceding
contrivances seem to be far preferable.

_a_, _a_, is the tub for receiving the apparatus, whose central upright
shaft _b_, rests upon a step _c_, in the bottom, and revolves at top in
a bush at _d_, made fast to a bar _e_, fixed flat across the mouth of
the tub. The shaft may be driven by the two bevel wheels _f_, _f_, at
right angles to each other, and the horizontal rod turned by hand; or
the whole may be impelled by any power. _g_, is an iron basin for
receiving the cold water from the spout _h_, supplied by a well; it
flows out of the basin through two tubes _i i_, down into the lower part
of the cooler _k k_. The cooler consists of two flat vessels, both of
which are formed of a flat interior plate, and an arched exterior one,
so that their transverse section is plano-convex. The water which flows
along the tubes _i i_, spreads itself upon the bottom of the cooler, and
then rises through the scabbard-shaped tubes _l l_, &c., into the upper
annular vessel _m m_; whence it is urged by hydrostatic pressure, in a
now heated state, through the slanting tubes _n n_, which terminate in
the common pipe _o_, of the annular basin _p p_, and is thence
discharged by the pipe _q_. The basin _p p_, is supported by the two
bearers _r_, made fast to the cross-beam _e_. There is in the lowest
part of the hollow ring at bottom, a screw plug, which may be opened
when it is desired to discharge the whole contents, and to wash it with
a stream of water.


REGULUS, is a term introduced, by the alchemists, now nearly obsolete.
It means literally a little king, and refers to the metallic state as
one of royalty, compared with the native earthy condition. Antimony is
the only metal now known by the name of regulus.


RESINS (_Résines_, Fr.; _Harze_, Germ.); are proximate principles found
in most vegetables, and in almost every part of them; but the only
resins which merit a particular description, are those which occur
naturally in such quantities as to be easily collected or extracted.
They are obtained chiefly in two ways, either by spontaneous exudation
from the plants, or by extraction by heat and alcohol. In the first
case, the discharge of resin in the liquid state is sometimes promoted
by artificial incisions made in summer through the bark into the wood of
the tree.

Resins possess the following general properties:--They are soluble in
alcohol, insoluble in water, and melt by the application of heat, but do
not volatilize without partial decomposition. They have rarely a
crystalline structure, but, like gums, they seldom affect any peculiar
form. They are almost all translucid, not often colourless, but
generally brown, occasionally red or green. Any remarkable taste or
smell, which they sometimes possess, may be ascribed to some foreign
matter, commonly an essential oil. Their specific gravity varies from
0·92 to 1·2. Their consistence is also very variable. The greater part
are hard, with a vitreous fracture, and so brittle as to be readily
pulverized in the cold. Some of them are soft, a circumstance probably
dependent upon the presence of a heterogeneous substance. The hard
resins do not conduct electricity, and they become negatively electrical
by friction. When heated, they melt more or less easily into a thick
viscid liquid, and concrete, on cooling, into a smooth shining mass, of
a vitreous fracture, which occasionally flies off into pieces, like
Prince Rupert’s drops; especially after being quickly cooled, and
scratched with a sharp point. They take fire by contact of an ignited
body, and burn with a bright flame, and the diffusion of much sooty
smoke. When distilled by themselves in close vessels, they afford
carbonic acid and carburetted gases, empyreumatic oil of a less
disagreeable smell than that emitted by other such oils, a little
acidulous water, and a very little shining charcoal. See ROSIN GAS.

Resins are insoluble in water, but dissolve in considerable quantities
in alcohol, both hot and cold. This solution reddens tincture of litmus,
but not syrup of violets; it is decomposed by water, and a milkiness
ensues, out of which the particles of the resin gradually agglomerate.
In this state it contains water, so as to be soft, and easily kneaded
between the fingers; but it becomes hard and brittle again when freed by
fusion from the water. The resins dissolve in ether and the volatile
oils, and, with the aid of heat, combine with the unctuous oils. They
may be combined by fusion with sulphur, and with a little phosphorus.
Chlorine water bleaches several coloured resins, if they be diffused in
a milky state through water. The carburet of sulphur dissolves them.

Resins are little acted upon by acids, except by the nitric, which
converts them into artificial tan. They combine readily with the alkalis
and alkaline earths, and form what were formerly reckoned soaps: but the
resins are not truly saponified; they rather represent the acid
constitution themselves, and, as such, saturate the salifiable bases.

Every resin is a natural mixture of several other resins, as is the case
also with oils; one principle being soluble in cold alcohol, another in
hot, a third in ether, a fourth in oil of turpentine, a fifth in
naphtha, &c. The soft resins, which retain a certain portion of volatile
oil, constitute what are called balsams. Certain other balsams contain
benzoic acid. The solid resins are, _amber_, _animé_, _benzoin_,
_colophony_ (common rosin), _copal_, _dammara_, _dragon’s blood_,
_elemi_, _guaiac_, _lac_, resin of _jalap_, _ladanum_, _mastic_,
_sandarach_, _storax_, _takamahac_.


RESIN, KAURI or COWDEE, is a new and very peculiar substance, recently
imported in considerable quantities from New Zealand, which promises to
be useful in the arts. It oozes from the trunk of a noble tree called
_Dammara australis_, or _Pinus kauri_, which rises sometimes to the
height of 90 feet without a branch, with a diameter of 12 feet, and
furnishes a log of heart timber of 11 feet. The resin, which is called
Cowdee gum by the importers, is brought to us in pieces varying in size
from that of a nutmeg to a block of 2 or 3 cwts. The colour varies from
milk-white to amber, or even deep brown; some pieces are transparent and
colourless. In hardness it is intermediate between copal and resin. The
white milky pieces are somewhat fragrant, like elemi. Specific gravity,
1·04 to 1·06. It is very inflammable, burns all away with a clear bright
flame, but does not drop. When cautiously fused, it concretes into a
transparent hard tough mass, like shellac. It affords a fine varnish
with alcohol, being harder and less coloured than mastic, while it is as
soluble, and may be had probably at one-tenth of the price. A solution
in alcohol, mixed with one-fourth of its bulk of a solution in oil of
turpentine, forms an excellent varnish, which dries quickly, is quite
colourless, clear, and hard. It is insoluble in pyro-acetic (pyroxilic?)
spirit. Combined with shellac and turpentine, it forms a good
sealing-wax.


REVERBERATORY FURNACE; see COPPER, IRON, and SODA.


RETORT. For producing coal gas, there are many modifications, varying in
dimension and shape with the caprice of the constructor, and in many
cases, without any definite idea of the principle to be aimed at.

They may be divided into three general classes:

1st. The circular retort, from twelve to twenty inches in diameter, and
from six to nine feet in length. This retort is used in Manchester and
some other places, in general for the distillation of cannel, or Scotch
parrot coal. It answers for the distillation of a coal which retains its
form in lumps, and is advantageous only from the facility with which its
position is changed, when partially destroyed by the action of fire on
the under side.

2nd. The small or London D retort, so called in consequence of its
having first been used by the chartered company in London, being still
in use at their works, and recommended by their engineer. This retort
is 12 inches broad on the base, 11 inches high, and 7 feet long,
carbonizing one and a half to two bushels at a charge.

3rd. The York D retort, (so called in consequence of its having been
introduced by Mr. Outhit, of York,) and the modifications of it, among
which I should include the elliptic retort, as having the same general
purpose in view. The difference between the London and York D retorts,
consists only in an extension of surface upon which the coal is spread.
See GAS-LIGHT.


RHODIUM, is a metal discovered by Dr. Wollaston in 1803, in the ore of
platinum. It is contained to the amount of three per cent. in the
platinum ore of Antioquia in Colombia, near Barbacoas; it occurs in the
Ural ore, and, alloyed with gold, in Mexico. The palladium having been
precipitated from the muriatic solution of the platinum ore previously
saturated with soda, by the cyanide of mercury, muriatic acid is to be
poured into the residuary liquid, and the mixture is to be evaporated to
dryness, to expel the hydrocyanic acid, and convert the metallic salts
into chlorides. The dry mass is to be reduced to a very fine powder, and
washed with alcohol of specific gravity 0·837. This solvent takes
possession of the double chlorides which the sodium forms with the
platinum, iridium, copper, and mercury, and does not dissolve the double
chloride of rhodium and sodium, but leaves it in the form of a powder,
of a fine dark-red colour. This salt being washed with alcohol, and then
exposed to a very strong heat, affords the rhodium. But a better mode of
reducing the metal upon the small scale, consists in heating the double
chloride gently in a glass tube, while a stream of hydrogen passes over
it, and then to wash away the chloride of sodium with water.

Rhodium resembles platinum in appearance. Any heat which can be produced
in a chemical furnace is incapable of fusing it; and the only way of
giving it cohesive solidity, is to calcine the sulphuret or arseniuret
of rhodium in an open vessel at a white heat, till all the sulphur or
arsenic be expelled. A button may thus be obtained, somewhat spongy,
having the colour and lustre of silver. According to Wollaston, the
specific gravity of rhodium is 11. It is insoluble by itself in any
acid; but when an alloy of it with certain metals, as platinum, copper,
bismuth, or lead, is treated with aqua regia, the rhodium dissolves
along with the other metals; but when alloyed with gold or silver, it
will not dissolve along with them. It may, however, be rendered very
soluble by mixing it in the state of a fine powder with chloride of
potassium or sodium, and heating the mixture to a dull-red heat, in a
stream of chlorine gas. It thus forms a triple salt, very soluble in
water. The solutions of rhodium are of a beautiful rose colour, whence
its name. In the dry way, it dissolves by heat in bisulphate of potassa;
and disengages sulphurous acid gas in the act of solution. There are two
oxides of rhodium. Rhodium combines with almost all the metals; and, in
small quantity, melted with steel, it has been supposed to improve the
hardness, closeness, and toughness of this metal. Its chief use at
present is for making the inalterable nibs of the so-named rhodium pens.


RIBBON MANUFACTURE, is a modification of WEAVING, which see.


RICE, of Carolina, analyzed by Braconnot, was found to be composed of
starch 85·07, of gluten 3·60, of gum 0·71, of uncrystallizable sugar
0·29, of a colourless rancid fat like suet 0·13, of vegetable fibre 4·8,
of salts with potash and lime bases 0·4, and 5·0 of water.

The quantity of rice entered for home consumption in the year 1836,
was--

                     Cwts.    81,610.    In 1837, 126,739.
  Ditto in the husk, Bushels 292,444.             282,377.

_Rice Paper_, as it is called, on which the Chinese and Hindoos paint
flowers so prettily, is a membrane of the bread-fruit tree, the
_Artocarpus incisifolia_ of naturalists.


RICE CLEANING. Various machines have been contrived for effecting this
purpose, of which the following, secured by patent to Mr. Melvil Wilson,
in 1826, may be regarded as a good specimen. It consists of an oblong
hollow cylinder, laid in an inclined position, having a great many teeth
stuck in its internal surface, and a central shaft also furnished with
teeth. By the rapid revolution of the shaft, its teeth are carried
across the intervals of those of the cylinder with the effect of parting
the grains of rice, and detaching whatever husks or impurities may
adhere to them. A hopper is set above to receive the rice, and conduct
it down into the cleansing cylinder.

About 80 teeth are supposed to be set in the cylinder, projecting so as
to reach very nearly the central shaft; in which there is a
corresponding number of teeth, that pass freely between the former.

The cylinder is shown inclined in the figure which accompanies the
specification; but it may be placed also upright or horizontal, and may
be mounted in any convenient frame-work. The central shaft should be put
in rapid rotation, while the cylinder receives a slow motion in the
opposite direction. The rice, as cleaned by that action, is discharged
at the lower end of the cylinder, where it falls into a shute (shoot),
and is conducted to the ground. The machine may be driven by hand, or by
any other convenient power.

Rice consists chiefly of starch, and therefore cannot by itself make a
proper bread. It is used in the cotton factories to form weavers’
dressings for warps. The Chinese reduce its flour into a pulp with hot
water, and mould it into figures and plates, which they afterwards
harden, and ornament with engravings, resembling those of
mother-of-pearl. When a decoction of rice is fermented and distilled, it
affords the sort of ardent spirit called _arrack_ in the East Indies.


RIFLE; see FIRE ARMS.

[Illustration: 941]


RINSING MACHINE, is one of those ingenious automatic contrivances for
economizing labour, and securing uniformity of action, now so common in
the factories of Lancashire. _Fig._ 941. is a longitudinal middle
section of an approved mechanism for rinsing pieces of calico dyed with
spirit or fancy colours, and which require more delicate treatment than
is compatible with hand-washing. A, E, F, B, is a wooden cistern, about
12 feet long, 4 feet high at one end, 2 feet at the other, and of the
ordinary width of calico cloth. It is divided transversely into a series
of equal compartments by partitions, decreasing in height from the upper
to the lower end, the top of each of them, however, being an inch at
least under the top of the enclosing side at its line of junction. Above
the highest end of the trough, a pair of squeezing rollers is mounted at
B; the lower one having a pulley upon the end of its shaft, for turning
it, by means of a band from one of the driving-shafts of the factory;
and the upper one is pressed down upon it by weighted levers acting on
the ends of its axis. The roller above the second highest partition has
also a pair of squeezing rollers, with a weighted lever D. The pieces of
cloth, stitched endwise, being laid upon a platform to the right hand of
the cistern, are introduced over the roller A, passed down under the
roller beneath it, and so up and down in a serpent-like path, from the
lowest compartment of the cistern to the uppermost, being drawn through
the series by the traction of the rotatory roller at B. While the long
web is thus proceeding upwards from A to B, a stream of pure water is
made to flow along in the opposite direction from B to A, running over
the top of each partition in a thin sheet. By this contrivance, the
goods which enter at A, having much loose colour upon their surface,
impregnate the water strongly, but as they advance they continually get
cleaner by the immersion, and pressure of the successive rollers, being
exposed to purer water, till at last they reach the limpid stream, and
are discharged at B perfectly bright. The rinsing operation may be
modified by varying the quantity of water admitted, the speed with which
the pieces are drawn through the cells, or the pressure upon the series
of top rollers.


ROCKETS. M. de Montgery, captain of a frigate in the French service, has
written a _Traité sur les Fusées de Guerre_, in which he discusses the
merits of the Congreve rockets, and describes methods of imitating them.
As the subject of military projectiles is foreign to this Dictionary, I
refer my readers to the above work, which is commended by the editor of
the _Dictionnaire Technologique_.


ROLLING-MILL. See IRON, MINT, and PLATED MANUFACTURE.


ROPE-MAKING. The fibres of hemp which compose a rope, seldom exceed in
length three feet and a half, at an average. They must, therefore, be
twined together so as to unite them into one; and this union is effected
by the mutual circumtorsion of the two fibres. If the compression
thereby produced be too great, the strength of the fibres at the points
where they join will be diminished; so that it becomes a matter of great
consequence to give them only such a degree of twist as is essential to
their union.

The first part of the process of rope-making by hand, is that of
spinning the yarns or threads, which is done in a manner analogous to
that of ordinary spinning. The spinner carries a bundle of dressed hemp
round his waist; the two ends of the bundle being assembled in front.
Having drawn out a proper number of fibres with his hand, he twists them
with his fingers, and fixing this twisted part to the hook of a whirl,
which is driven by a wheel put in motion by an assistant, he walks
backwards down the rope walk, the twisted part always serving to draw
out more fibres from the bundle round his waist, as in the flax-spinning
wheel. The spinner takes care that these fibres are equably supplied,
and that they always enter the twisted parts by their ends, and never by
their middle. As soon as he has reached the termination of the walk, a
second spinner takes the yarn off the whirl, and gives it to another
person to put upon a reel, while he himself attaches his own hemp to the
whirl hook, and proceeds down the walk. When the person at the reel
begins to turn, the first spinner, who has completed his yarn, holds it
firmly at the end, and advances slowly up the walk, while the reel is
turning, keeping it equally tight all the way, till he reaches the reel,
where he waits till the second spinner takes his yarn off the whirl
hook, and joins it to the end of that of the first spinner, in order
that it may follow it on the reel.

The next part of the process previous to tarring, is that of warping the
yarns, or stretching them all to one length, which is about 200 fathoms
in full-length rope-grounds, and also in putting a slight turn or twist
into them.

The third process in rope-making, is the tarring of the yarn. Sometimes
the yarns are made to wind off one reel, and, having passed through a
vessel of hot tar, are wound upon another, the superfluous tar being
removed by causing the yarn to pass through a hole surrounded with
spongy oakum; but the ordinary method is to tar it in skains or hanks,
which are drawn by a capstan with a uniform motion through the
tar-kettle. In this process, great care must be taken that the tar is
boiling neither too fast nor too slow. Yarn for cables requires more tar
than for hawser-laid ropes; and for standing and running rigging, it
requires to be merely well covered. Tarred cordage has been found to be
weaker than what is untarred, when it is new; but the tarred rope is not
so easily injured by immersion in water.

The last part of the process of rope-making, is to lay the cordage. For
this purpose two or more yarns are attached at one end to a hook. The
hook is then turned the contrary way from the twist of the individual
yarn, and thus forms what is called a strand. Three strands, sometimes
four, besides a central one, are then stretched at length, and attached
at one end to three contiguous but separate hooks, but at the other end
to a single hook; and the process of combining them together, which is
effected by turning the single book in a direction contrary to that of
the other three, consists in so regulating the progress of the twists of
the strands round their common axis, that the three strands receive
separately at their opposite ends just as much twist as is taken out of
them by their twisting the contrary way, in the process of combination.

Large ropes are distinguished into two main classes, the _cable-laid_
and _hawser-laid_. The former are composed of nine strands, namely,
three great strands, each of these consisting of three smaller secondary
strands, which are individually formed with an equal number of primitive
yarns. A cable-laid rope eight inches in circumference, is made up of
333 yarns or threads, equally divided among the nine secondary strands.
A _hawser-laid_ rope consists of only three strands, each composed of a
number of primitive yarns, proportioned to the size of the rope; for
example, if it be eight inches in circumference, it may have 414 yarns,
equally divided among three strands. Thirty fathoms of yarn are reckoned
equivalent in length to eighteen fathoms of rope cable-laid, and to
twenty fathoms hawser-laid. Ropes of from one inch to two inches and a
half in circumference are usually hawser-laid; of from three to ten
inches, are either hawser or cable laid; but when more than ten inches,
they are always cable-laid.

Every hand-spinner in the dock-yard is required to spin, out of the best
hemp, six threads, each 160 fathoms long, for a quarter of a day’s work.
A hawl of yarn, in the warping process, contains 336 threads.

The following are Captain Huddart’s improved principles of the rope
manufacture:--

1. To keep the yarns separate from each other, and to draw them from
bobbins revolving upon skewers, so as to maintain the twist while the
strand or primary cord is forming.

2. To pass them through a register, which divides them by circular
shells of holes; the number in each concave shell being conformable to
the distance from the centre of the strand, and the angle which the
yarns make with a line parallel to it, and which gives them a proper
position to enter.

3. To employ a tube for compressing the strand, and preserving the
cylindrical figure of its surface.

4. To use a gauge for determining the angle which the yarns in the
outside shell make with a line parallel to the centre of the strand,
when registering; because according to the angle made by the yarns in
this shell, the relative lengths of all the yarns in the strand will be
determined.

5. To harden up the strand, and thereby increase the angle in the
outside shell; which compensates for the stretching of the yarns, and
the compression of the strands.

A great many patents have been obtained, and worked with various degrees
of success, for making ropes. Messrs. Cartwright, Fothergill, Curr,
Chapman, Balfour, and Huddart, have been the most conspicuous inventors
in this country; but the limits of this work preclude us doing justice
to their respective merits.

All improvements in the manufacture of cordage at present in use, either
in her Majesty’s yards or in private rope-grounds, owe their superiority
over the old method of making cordage to Captain Huddart’s invention of
the register plate and tube.

Mr. Balfour took out a patent for the manufacture of cordage about a
month before Captain Huddart; but the formation of his strand was to be
accomplished by what he called a top minor, (in the form of a common
top, with pins to divide the yarns,) which upon trial could not make
cordage so good as by the common mode. On seeing Captain Huddart’s
specification, Mr. Balfour, five years after, procured another patent,
in which he included a plate and tube, but which was not sufficiently
correct, and experience in the navy proved the insufficiency of the
cordage. Captain Huddart’s plate and tube were then adopted in the
king’s yards, and he gave his assistance for the purpose.

Captain Huddart then invented and took a patent for a machine, which by
registering the strand at a short length from the tube, and winding it
up as made, preserved an uniformity of twist, or angle of formation,
from end to end of the rope, which cannot be accomplished by the method
of forming the strands down the ground, where the twist is communicated
from one end to the other of an elastic body upwards of 300 yards in
length. This registering-machine was constructed with such correctness,
that when some were afterwards required, no alteration could be made
with advantage by the most skilful and scientific mechanic of that day,
Mr. Rennie. Thus the cold register was carried to the greatest
perfection.

A number of yarns cannot be put together in a cold state, without
considerable vacancies, into which water may gain admission; Captain
Huddart, therefore, formed the yarns into a strand immediately as they
came from the tar-kettle, which he was enabled to do by his
registering-machine, and the result was most satisfactory. This
combination of yarns was found by experiment to be 14 per cent. stronger
than the cold register; it constituted a body of hemp and tar impervious
to water, and had great advantage over any other cordage, particularly
for shrouds, as after they were settled on the mast-head, and properly
set up, they had scarcely any tendency to stretch, effectually secured
the mast, and enabled the ship to carry the greatest press of sail.

In order more effectually to obtain correctness in the formation of
cables and large cordage, Captain Huddart constructed a laying-machine,
which has carried his inventions in rope-making to the greatest
perfection, and which, founded on true mathematical principles, and the
most laborious calculations, is one of the noblest monuments of
mechanical ability since the improvement of the steam-engine by Mr.
Watt. By this machine, the strands receive that degree of twist only
which is necessary, and are laid at any angle with the greatest
regularity; the pressure is regulated to give the required elasticity,
and all parts of the rope are made to bear equally. In no one instance
has a rope or cable thus formed, been found defective in the lay, or
stiff, or difficult to coil.

Such a revolution in the manufacture of cordage could not be
accomplished without great expense, as the works at Limehouse fully
testify; and considerable opposition necessarily arose. Captain
Huddart’s first invention was, however, generally adopted, as soon as
the patent expired; and experience has established the great importance
of his subsequent improvements.

His cordage has been supplied in large quantities to her Majesty’s navy,
and has received the most satisfactory reports.

The following description of one of the best modern machines for making
ropes on Captain Huddart’s plan, will gratify the intelligent reader.

[Illustration: 942]

_Fig._ 942. exhibits a side elevation of the tackle-board and
bobbin-frame at the head of the ropery, and also of the carriage or
rope-machine in the act of hauling out and twisting the strands.

[Illustration: 943 944 945 946]

_Fig._ 943. is a front elevation of the carriage.

_Fig._ 944. is a yarn-guide, or board, or plate, with perforated holes
for the yarns to pass through before entering the nipper.

_Figs._ 945. and 946. are side and front views of the nipper for
pressing the rope-yarns.

_a_ is the frame for containing the yarn bobbins. The yarns are brought
from the frame, and pass through a yarn-guide at _b_. _c_ is a small
roller, under which the rope-yarns pass; they are then brought over the
reel _d_, and through another yarn-guide _e_, after which they enter the
nippers at _v_, and are drawn out and formed into strands by the
carriage. The roller and reel may be made to traverse up and down, so as
to regulate the motion of the yarns.

The carriage runs on a railway. _f_, _f_, is the frame of the carriage;
_g_, _g_, are the small wheels on which it is supported; _k_, _k_, is an
endless rope, reaching from the head to the bottom of the railway, and
is driven by a steam-engine; _m_, _m_, is a wheel with gubs at the back
of it, over which the endless rope passes, and gives motion to the
machinery of the carriage. _n_, is the ground rope for taking out the
carriage, as will be afterwards described. On the shaft of _m_, _m_, are
two bevel wheels 3, 3, with a shifting catch between them; these bevel
wheels are loose upon the shaft, but when the catch is put into either
of them, this last then keeps motion with the shaft, while the other
runs loose. One of these wheels serves to communicate the twist to the
strand in drawing out; the other gives the opposite or after turn to the
rope in closing. 4, 4, is a lever for shifting the catch accordingly. 5,
is a third bevel wheel, which receives its motion from either of the
other two, and communicates the same to the two spur wheels 6, 6, by
means of the shaft _x_. These can be shifted at pleasure; so that by
applying wheels of a greater or less number of teeth above and beneath,
the twist given to the strands can be increased or diminished
accordingly. The upper of these two communicates motion, by means of the
shaft _o_, to another spur wheel 8, which working in the three pinions
above, 9, 9, gives the twist to the strand hooks.

The carriage is drawn out in the following manner. On the end of the
shaft of _m_, _m_, is the pinion 3, which, working in the large wheel R,
gives motion to the ground-rope shaft upon its axis. In the centre of
this shaft is a curved pulley or drum _t_, round which the ground rope
takes one turn. This rope is fixed at the head and foot of the ropery;
so that when the machinery of the carriage is set a-going by the endless
rope _k_, _k_, and gives motion to the ground-rope shaft, as above
described, the carriage will necessarily move along the railway; and the
speed may be regulated either by the diameter of the circle formed by
the gubs on the wheel _m_, _m_, or by the number of teeth in the pinion
3. At T, is a small roller, merely for preventing the ground rope from
coming up among the machinery. At the head of the railway, and under the
tackle-board, is a wheel and pinion Z, with a crank for tightening the
ground rope. The fixed machinery at the head, for hardening or tempering
the strands, is similar to that on the carriage, with the exception of
the ground-rope geer, which is unnecessary. The motion is communicated
by another endless rope, (or short band, as it is called, to distinguish
it from the other,) which passes over gubs at the back of the wheel 1,
1.

When the strands are drawn out by the carriage to the requisite length,
the spur wheels 3, R, are put out of geer. The strands are cut at the
tackle-board, and fixed to the hooks 1, 1, 1; after which they are
hardened or tempered, being twisted at both ends. When this operation is
finished, three strands are united on the large hook _h_, the top put
in, and the rope finished in the usual way.

In preparing the hemp for spinning an ordinary thread or rope-yarn, it
is only heckled over a large keg or clearer, until the fibres are
straightened and separated, so as to run freely in the spinning. In this
case, the hemp is not stript of the tow, or cropt, unless it is designed
to spin beneath the usual grist, which is about 20 yarns for the strand
of a three-inch strap-laid rope. The spinning is still performed by
hand, being found not only to be more economical, but also to make a
smoother thread, than has yet been effected by machinery. Various ways
have been tried for preparing the yarns for tarring. That which seems
now to be most generally in use, is, to warp the yarns upon the stretch
as they are spun. This is accomplished by having a wheel at the foot, as
well as the head of the walk, so that the men are able to spin both up
and down, and also to splice their threads at both ends. By this means,
they are formed into a haul, resembling the warp of a common web, and a
little turn is hove into the haul, to preserve it from getting foul in
the tarring. The advantages of warping from the spinners, as above,
instead of winding on winches, as formerly, are, 1st, the saving of this
last operation altogether; 2dly, the complete check which the foreman
has of the quantity of yarn spun in the day; 3dly, that the quality of
the work can be subjected to the minutest inspection at any time. In
tarring the yarn, it is found favourable to the fairness of the strip,
to allow it to pass around or under a reel or roller in the bottom of
the kettle while boiling, instead of coiling the yarn in by hand. The
tar is then pressed from the yarn, by means of a sliding nipper, with a
lever over the upper part, and to the end of which the necessary weight
is suspended. The usual proportion of tar in ordinary ropes, is
something less than a fifth. In large strap-laid ropes, which are
necessarily subjected to a greater press in the laying of them, the
quantity of tar can scarcely exceed a sixth, without injuring the
appearance of the rope when laid.

For a long period, the manner of laying the yarns into ropes, was by
stretching the haul on the rope-ground, parting the number of yarns
required for each strand, and twisting the strands at both ends, by
means of hand-hooks, or cranks. It will be obvious that this method,
especially in ropes of any considerable size, is attended with serious
disadvantages. The strand must always be very uneven; but the principal
disadvantage, and that which gave rise to the many attempts at
improvement, was, that the yarns being all of the same length before
being twisted, it followed, when the rope was finished, that while those
which occupied the circumference of the strand were perfectly tight, the
centre yarns, on the other hand, as they were now greatly slackened by
the operation of hardening or twisting the strands, actually would bear
little or no part of the strain when the rope was stretched, until the
former gave way. The method displayed in the preceding figures and
description, is among the latest and most improved; Every yarn is given
out from the bobbin frame as it is required in twisting the rope; and
the twist communicated in the out-going of the carriage, can be
increased or diminished at pleasure. In order to obtain a smooth and
well-filled strand, it is necessary also, in passing the yarns through
the upper board, to proportion the number of centre to that of outside
yarns. In ordinary sized ropes, the strand seems to have the fairest
appearance, when the outside yarns form from 2/3ds to 3/4ths of the
whole quantity, in the portion of twist given by the carriage in drawing
out and forming the strands.

[Illustration: 947 948 949]

In laying cables, torsion must be given both behind and before the
laying top. _Figs._ 947, 948, 949. represent the powerful patent
apparatus employed for this purpose. A, is a strong upright iron pillar,
supported upon the great horizontal beam N, N, and bearing at its upper
end the three-grooved laying top M. H, H, are two of the three great
bobbins or reels round which the three secondary strands or small
hawsers are wound. These are drawn up by the rotation of the three
feeding rollers I, I, I, thence proceed over the three guide pulleys K,
K, K, towards the laying top M, and finally pass through the tube O, to
be wound upon the cable-reel D. The frames of the three bobbins H, H, H,
do not revolve about the fast pillar A, as a common axis; but each
bobbin revolves round its own shaft Q, which is steadied by a bracing
collet at N, and a conical step at its bottom. The three bobbins are
placed at an angle of 120 degrees apart, and each receives a rotatory
motion upon its axis from the toothed spur wheel B, which is driven by
the common central spur wheel C. Thus each of the three secondary cords
has a proper degree of twist put into it in one direction, while the
cable is laid, by getting a suitable degree of twist in an opposite
direction, from the revolution of the frame or cage G, G, round two
pivots, the one under the pulley E, and the other over O. The reel D
has thus, like the bobbins H, H, two movements; that in common with its
frame, and that upon its axis, produced by the action of the endless
band round the pulley E, upon one of its ends, and the pulley E´ above
its centre of rotation. The pulley E is driven by the bevel mill-geering
P, P, P, as also the under spur wheel C. L, in _fig._ 949., is the place
of the ring L, _fig._ 947., which bears the three guide pulleys K, K, K.
_Fig._ 948. is an end view of the bobbin H, to show the worm or endless
screw J, of _fig._ 949., working into the two snail-toothed wheels, upon
the ends of the two feed-rollers I, I, which serve to turn them. The
upright shafts of J, J, receive their motion from pulleys and cords near
their bottom. Instead of these pulleys, and the others E, E´,
bevel-wheel geering has been substituted with advantage, not being
liable to slip, like the pulley-band mechanism. The axis of the great
reel is made twice the length of the bobbin D, in order to allow of the
latter moving from right to left, and back again alternately, in winding
on the cable with uniformity as it is laid. The traverse mechanism of
this part is, for the sake of perspicuity, suppressed in the figure.

Mr. William Norvell, of Newcastle, obtained a patent in May, 1833, for
an improvement adapted to the ordinary machines employed for twisting
hempen yarns into strands, affording, it is said, a simpler and more
eligible mode of accomplishing that object, and also of laying the
strands together, than has been hitherto effected by machinery. The
yarns spun from the fibres of hemp, are wound upon bobbins, and these
bobbins are mounted upon axles, and hung in the frame of the machine, as
shown in the elevation, _fig._ 950., from which bobbins the several ends
of yarn are passed upwards through slanting tubes; by the rotation of
which tubes, and of the carriages in which the bobbins are suspended,
the yarns become twisted into strands, and also the strands are laid so
as to form ropes.

[Illustration: 950]

His improvements consist, first, in the application of three or more
tubes, two of which are shown in _fig._ 950, placed in inclined
positions, so as to receive the strands immediately above the
press-block _a_, _a_, and nearly in a line with A, the point of closing
or laying the rope. B¹, and B³, are opposite side views; B², an edge
view; and B, a side section of the same. He does not claim any exclusive
right of patent for the tubes themselves, but only for their form and
angular position.

Secondly, in attaching two common flat sheaves, or pulleys, C, C, _fig._
950., to each of the said tubes, nearly round which each strand is
lapped or coiled, to prevent it from slipping, as shown in the section
B¹. The said sheaves or pulleys are connected by a crown or centre wheel
D, loose upon _b_, _b_, the main or upright axle; E, E, is a smaller
wheel upon each tube, working into the said crown or centre wheel, and
fixed upon the loose box I, on each of the tubes.

F, F, is a toothed or spur wheel, fixed also upon each of the loose
boxes I, and working into a smaller wheel G, upon the axis 2, of each
tube; H, is a bevel wheel fixed upon the same axis with G, and working
into another bevel wheel _J_, fixed upon the cross axle 3, of each tube;
K, is a spur wheel attached to the same axis with _J_, at the opposite
end, and working into L, another spur wheel of the same size upon each
of the tubes. By wheels thus arranged and connected with the sheaves or
pulleys, as above described, a perfectly equal strain or tension is put
upon each strand as drawn forward over the pulley C.

Thirdly, the invention consists in the introduction of change wheels M,
M, M, M, _fig._ 950., for putting the forehard or proper twist into each
strand before the rope is laid; this is effected by small spindles on
axles 4, 4, placed parallel with the line of each tube B.

Upon the lower end of each spindle the bevel wheels N, N, are attached,
and driven by other bevel wheels O, O, fixed immediately above each
press-block _a_, _a_. On the top end of each spindle or axle 4, 4, is
attached one of the change wheels, working into the other change wheel
fixed upon the bottom end of each of the tubes, whereby the forehard or
proper twist in the strands for all sizes of ropes, is at once attained,
by simply changing the sizes of those two last described wheels, which
can be very readily effected, from the manner in which they are attached
to the tubes B, B, and 4, 4.

From the angular position of the tubes towards the centre, the strands
are nearly in contact at their upper ends, where the rope is laid,
immediately below which the forehard or proper twist is given to the
strands.

Fourthly, in the application of a press-block P, of metal, in two parts,
placed directly above and close down to where the rope is laid at A, the
inside of which is polished, and the under end is bell-mouthed; to
prevent the rope from being chafed in entering it, a sufficient grip or
pressure is put upon the rope by one or two levers and weights 5, 5,
acting upon the press-block, so as to adjust any trifling irregularity
in the strand or in the laying; the inside of which being polished,
gives smoothness, and by the said levers and weights, a proper tension
to the rope, as it is drawn forward through the press-block. By the
application of this block, ropes may be made at once properly stretched,
rendering them decidedly preferable and extremely advantageous,
particularly for shipping, inclined planes, mines, &c.

The preceding description includes the whole of Mr. Norvell’s
improvements; the remaining parts of the machine being similar to those
now in use, may be briefly described as follows:--A wheel or pulley _c_,
is fixed independently of the machine, over which the rope passes to the
drawing motion represented at the side; _d_, _d_, is a grooved wheel,
round which the rope is passed, and pressed into the groove by means of
the lever and weight _e_, _e_, acting upon the binding sheaf _f_, to
prevent the rope from slipping. After the rope leaves the said sheave,
it is coiled away at pleasure. _g_, _g_, are two change wheels, for
varying the speed of the grooved wheel _d_, _d_, to answer the various
sizes of ropes; _h_, is a spiral wheel, driven by the screw _k_, fixed
upon the axle _l_; _m_, is a band-wheel, which is driven by a belt from
the shaft of the engine, or any other communicating power; _n_, _n_, is
a friction strap and striking clutch. The axle _q_, is driven by two
change wheels _p_, _p_; by changing the sizes of those wheels, the
different speeds of the drum R, R, for any sizes of ropes, are at once
effected.

[Illustration: 951]

The additional axle _s_, and wheels _t_, _t_, shown in _fig._ 951., are
applied occasionally for reversing the motion of the said drums, and
making what is usually termed left-hand ropes; _u_, _figs._ 950. and
951., show a bevelled pinion, driving the main crown wheel _v_, _v_,
which wheel carries and gives motion to the drums R, R; _w_, _w_, is a
fixed or sun wheel, which gives a reverse motion to the drums, as they
revolve round the same, by means of the intervening wheels _x_, _x_,
_x_, whereby the reverse or retrograding motion is produced, and which
gives to the strands the right twist. The various retrograding motions,
or right twists for all sizes and descriptions of ropes, may be obtained
by changing the diameters of the pinions _y_, _y_, _y_, on the under
ends of the drum spindles; the carriages of the intervening wheels _x_,
_x_, _x_, being made to slide round the ring _z_, _z_; W, W, is the
framework of the machine and drawing motion; T, T, T, are the bobbins
containing the yarns; their number is varied to correspond with the
different sizes of the machines.

The machine here described, in elevation and plan, is calculated to make
ropes from three to seven and one-half inches in circumference, and to
an indefinite length.

Messrs. Chapman of Newcastle, to whom the art of rope-making is deeply
indebted, having observed that rope yarn is considerably weakened by
passing through the tar-kettle, that tarred cordage loses its strength
progressively in cold climates, and so rapidly in hot climates as to be
scarcely fit for use in three years, discovered that the deterioration
was due to the reaction of the mucilage and acid of the tar. They
accordingly proposed the following means of amelioration. 1. Boiling it
with water, in order to remove these two soluble constituents. 2.
Concentrating the washed tar by heat, till it becomes pitchy, and then
restoring the plasticity which it thereby loses, by the addition of
tallow, or animal or expressed oils.

In 1807, the same able engineers obtained a patent for a method of
making a belt or flat band, of two, three, or more strands of shroud or
hawser-laid rope, placed side by side, so as to form a band of any
desired breadth, which may be used for hoisting the kibbles and corves
in mine-shafts, without any risk of its losing twist by rotation. The
ropes should be laid with the twist of the one strand directed to the
right hand, that of the other to the left, and that of the yarns the
opposite way to the strands, whereby perfect flatness is secured to the
band. This parallel assemblage of strands has been found also to be
stronger than when they are all twisted into one cylinder. The patentees
at the same time contrived a mechanism for piercing the strands
transversely, in order to brace them firmly together with twine. Flat
ropes are usually formed of hawsers with three strands, softly laid,
each containing 33 yarns, which with four ropes, compose a cordage four
and a half inches broad, and an inch and a quarter thick, being the
ordinary dimensions of the grooves in the whim-pulleys round which they
pass.

RELATIVE STRENGTH of CORDAGE, shroud laid.

  +-------------+---------------++---------------++---------------+
  |Size.        |Warm Register. ||Cold Register. ||Common Staple. |
  +-------------+---+---+---+---++---+---+---+---++---+---+---+---+
  |             | T | C | Q | L || T | C | Q | L || T | C | Q | L |
  |3 inches bore| 3 |17 |   |16 || 3 | 5 | 3 |16 || 2 | 9 | 1 |24 |
  |3-1/2  --    | 5 | 5 |   |   || 4 | 9 | 2 |21 || 3 | 6 | 1 |27 |
  |4      --    | 6 |17 |   |16 || 5 |17 |   | 4 || 4 | 5 | 3 | 7 |
  |4-1/2  --    | 8 |13 | 2 | 8 || 7 | 5 | 3 | 1 || 5 | 1 | 2 | 6 |
  |5      --    |10 |14 | 1 | 4 || 9 | 3 |   | 4 || 6 | 9 | 2 | 8 |
  |5-1/2  --    |12 |19 | 2 | 4 ||11 | 1 | 1 |25 || 7 |12 |   |22 |
  |6      --    |14 |15 | 2 |24 ||13 | 3 | 2 | 8 || 8 |17 | 1 |20 |
  |6-1/2  --    |18 | 2 |   |10 ||15 | 9 | 1 | 9 || 9 |16 | 3 |14 |
  |7      --    |21 |   |   |   ||17 |18 | 3 | 8 ||11 | 4 | 1 |21 |
  |7-1/2  --    |24 | 2 |   |16 ||20 |11 | 3 | 9 ||12 | 8 | 3 | 6 |
  |8      --    |27 | 8 | 1 |26 ||23 | 8 | 2 | 8 ||13 | 2 | 3 |12 |
  +-------------+---+---+---+---++---+---+---+---++---+---+---+---+

  T = _Tons._
  C = _Cwt._
  Q = _Qrs._
  L = _Lbs._

The above statement is the result of several hundred experiments.


ROSIN, or COLOPHANY (_Galipot_, Fr.; _Fichtenharz_, Germ.); is the rosin
left after distilling off the volatile oil from the different species of
turpentine. Yellow rosin contains some water, which black rosin does
not. See TURPENTINE.


ROSIN GAS. _Fig._ 952. exhibits the retort and its appendages, as
erected by Messrs. Taylor and Martineau, under the direction of the
patentee, Professor Daniel, F.R.S.

I have introduced this manufacturing project, not as a pattern to
imitate, but as an example to deter; as affording a very instructive
lesson of the danger of rushing headlong into most extensive
enterprises, without fully verifying, upon a moderate scale, the
probability of their ultimate success. The capital, labour, and time
annually wasted upon visionary schemes of this sort, got up by chamber
chemists, are incalculably great. No more essential service could be
rendered to the cause of productive industry, than to unmask the
thousand and one chimerical inventions which disgrace our lists of
patents during the last thirty years. These remarks have been suggested
by the circumstance, that 50,000_l._ were squandered upon the rosin-gas
concern; a fact communicated to me by an eminent capitalist, who was
induced by fallacious statements to embark largely in the speculation.
Had 100_l._ been employed beforehand, by a dispassionate practical man,
in making judicious trials, and in calculating the chances of eventual
profit and loss, it would have been demonstrated, as clearly as noonday,
that rosin could never compete with pitcoal in the production of
gas-light. Whatever ingenuity was expended in getting up the following
apparatus, may be regarded as an additional _ignis fatuus_ to mislead
the public, and divert their thoughts from the abyss that lay before
them. The main preliminary to be settled, in all new undertakings, is
the soundness of the principle. By neglecting this point, projectors
perpetually realize the expiatory fable of the Danaïds.

[Illustration: 952]

The retort _e_, _e_, _fig._ 952., is seen charged with coke, which is in
the first instance raised to a bright red heat, by means of the furnace
beneath. The common brown rosin of commerce, which is deposited in the
tank _a_, is to be mixed with the essential oil (condensed from the
rosin vapours in a preceding operation) in the proportion of one hundred
pounds of the former to ten gallons of the latter. The influence of the
flame and heated air beneath serves to preserve this in a fluid state,
and by a damper passing across the aperture in the chimney the
temperature of the fluid may be exactly regulated. A wire-gauze screen
at _f_, reaches to the bottom of the tank, and prevents the solid rosin,
or any impurity with which it may be mixed, from choking the stopcock.

The melted rosin having passed by the stopcock _b_, funnel _c_, and
syphon _d_, into the retort, falls on the coke, and in its passage
through the ignited mass, becomes decomposed. On arriving at the other
end of the retort, a large portion of the oil of turpentine, in the
form of condensable vapour, is separated by the refrigerator _g_; this
is supplied with water from a cistern above, and the non-condensable
vapour or gas passes up the tube _h_, and dips beneath the surface of
the fluid in the vessel _i_. This completes the condensation; and the
gas proceeds in a perfectly pure state, by the pipe _k_, to the
gasometer, or rather to the floating reservoir, for use.

The essential oil, when it leaves the refrigerator, is conveyed, by the
syphon _l_, to a cistern beneath. The necessity for employing a syphon
will be apparent, when it is borne in mind that the tube prevents the
escape of the gas, which would otherwise pass away from the box with the
essential oil. Another pipe and syphon _m_, _n_, serve to convey the
condensed essential oil from the top cistern.


ROTTEN-STONE. See TRIPOLI.


ROUGE. (_Fard_, Fr.) The only cosmetic which can be applied without
injury to brighten a lady’s complexion, is that prepared, by the
following process, from safflower (_Carthamus tinctorius_). The flowers,
after being washed with pure water till it comes off colourless, are
dried, pulverized, and digested with a weak solution of crystals of
soda, which assumes thereby a yellow colour. Into this liquor a quantity
of finely carded white cotton wool is plunged, and then so much lemon
juice or pure vinegar is added as to supersaturate the soda. The
colouring matter is disengaged, and falls down in an impalpable powder
upon the cotton filaments. The cotton, after being washed in cold water,
to remove some yellow colouring particles, is to be treated with a fresh
solution of carbonate of soda, which takes up the red colouring matter
in a state of purity. Before precipitating this pigment a second time by
the acid of lemons, some soft powdered talc should be laid in the bottom
of the vessel, for the purpose of absorbing the fine rouge, in
proportion as it is separated from the carbonate of soda, which now
holds it dissolved. The coloured mixture must be finally triturated with
a few drops of olive-oil, in order to make it smooth and marrowy. Upon
the fineness of the talc, and the proportion of the safflower
precipitate which it contains, depend the beauty and value of the
cosmetic. The rouge of the above second precipitation is received
sometimes upon bits of fine-twisted woollen stuff, called _crepons_,
which ladies rub upon their cheeks.


RUBY. See LAPIDARY.


RUM, is a variety of ardent spirits, distilled in the West Indies, from
the fermented skimmings of the sugar teaches, mixed with molasses, and
diluted with water to the proper degree. A sugar plantation in Jamaica
or Antigua, which makes 200 hogsheads of sugar, of about 16 cwt. each,
requires, for the manufacture of its rum two copper stills; one of 1000
gallons for the wash, and one of 600 gallons for the low wines, with
corresponding worm refrigeratories. It also requires two cisterns, one
of 3000 gallons for the lees or spent wash of former distillations,
called dunder (_Quasi redundar_, Span.), another for the skimmings of
the clarifiers and teaches of the sugar-house; along with twelve, or
more, fermenting cisterns or tuns.

Lees that have been used more than three or four times, are not
considered to be equally fit for exciting fermentation, when mixed with
the sweets, as fresher lees. The wort is made, in Jamaica, by adding to
1000 gallons of dunder, 120 gallons of molasses, 720 gallons of
skimmings (= 120 of molasses in sweetness), and 160 gallons of water; so
that there may be in the liquid nearly 12 per cent. of solid saccharum.
Another proportion, often used, is 100 gallons of molasses, 200 gallons
of lees, 300 gallons of skimmings, and 400 of water; the mixture
containing, therefore, 15 per cent. of sweets. These two formulæ
prescribe so much spent wash, according to my opinion, as would be apt
to communicate an unpleasant flavour to the spirits. Both the fermenting
and flavouring principles reside chiefly in the fresh cane juice, and in
the skimmings of the clarifier; because, after the syrup has been
boiled, they are in a great measure dissipated. I have made many
experiments upon fermentation and distillation from West India molasses,
and always found the spirits to be perfectly exempt from any rum
flavour.

The fermentation goes on most uniformly and kindly in very large masses,
and requires from 9 to 15 days to complete; the difference of time
depending upon the strength of the wort, the condition of its
fermentable stuff, and the state of the weather. The progress of the
attenuation of the wash should be examined from day to day with a
hydrometer, as I have described in the article DISTILLATION. When it has
reached nearly to its _maximum_, the wash should be as soon as possible
transferred by pumps into the still, and worked off by a properly
regulated heat; for if allowed to stand over, it will deteriorate by
acetification. Dr. Higgins’s plan, of suspending a basket full of
limestone in the wash-tuns, to counteract the acidity, has not, I
believe, been found to be of much use. It would be better to cover up
the wash from the contact of atmospheric air, and to add perhaps a very
little _sulphite_ of lime to it, both of which means would tend to
arrest the acetous fermentation. But one of the best precautions against
the wash becoming sour, is to preserve the utmost cleanliness among all
the vessels in the distillery. They should be scalded at the end of
every round with boiling water and quicklime.

About 115 gallons of proof rum are usually obtained from 1200 gallons of
wash. The proportion which the product of rum bears to that of sugar, in
very rich moist plantations, is rated, by Edwards, at 82 gallons of the
former to 16 cwt. of the latter; but the more usual ratio is 200 gallons
of rum to 3 hogsheads of sugar. But this proportion will necessarily
vary with the value of rum and molasses in the market, since whichever
fetches the most remunerating price, will be brought forward in the
greatest quantity. In one considerable estate in the island of Grenada,
92 gallons of rum were made for every hogshead (16 cwts.) of sugar. See
STILL.

             Rum imported, in
           1835.      1836.      1837.
  Galls. 5,540,170; 4,993,942; 4,612,416.

      Retained for Home Consumption.--
        Duty 9_s._ per Imp. Gallon.
           1835.       1836.        1837.
  Galls. 3,416,966;  3,325,068;   3,184,599.


RUST, is the orange-yellow coat of peroxide which forms upon the surface
of iron exposed to moist air. Oil-paint, varnish, plumbago, or a film of
caoutchouc, may be employed, according to circumstances, to prevent the
rusting of iron utensils.


RYE, consists, according to the analysis of Einhof, of 24·2 of husk,
65·6 of flour, and 10·2 of water, in 100 parts. This chemist found in
100 parts of the flour, 61·07 of starch, 9·48 of gluten, 3·28 of
vegetable albumen, 3·28 of uncrystallizable sugar, 11·09 of gum, 6·38 of
vegetable fibre, and the loss was 5·62, including a vegetable acid not
yet investigated. Some phosphate of lime and magnesia are also present.
See GIN.




S.


SAFETY LAMP. I have reserved for this place an account of the patented
improvement made upon Davy’s lamp by Messrs. Upton and Roberts; the
latter of whom, having worked in coal mines from a boy, and having
observed, that in peculiar circumstances, the Davy was insecure, was led
to contrive certain modifications of it, for which he received, some
years ago, a reward from the Society of Arts. It appears from undoubted
experiments, that if a jet of carburetted hydrogen (coal gas for
example) be impelled with very moderate force against the side of the
Davy, it will first fill the wire cylinder of the burning lamp with
flame, and then take fire itself exteriorly. This passage of the flame
of explosive gases through the meshes of wire gauze of the fineness
prescribed for safety lamps by Sir H. Davy, was demonstrated in several
trials before the select committee of the House Commons on accidents in
mines, by Mr. Pereira, at the London University.[49] While the gas is at
rest, relatively to Davy’s lamp, the explosion has never been known to
pass; but “if,” says Mr. Pereira, “a lamp be held before a jet of gas
until it becomes hot (a red heat is not essential), and then gently
moved, the flame will pass, and the experiment may be repeated
successively a number of times in the minute.” Two layers of wire gauze,
though they greatly impede the transmission of light, will still permit
that of flame, in the above circumstances. In Upton and Roberts’ lamp,
there is but one coat of wire gauze, but it is enclosed in a glass
cylinder, in such a manner as to admit the air which feeds the flame
only under its bottom, first through an annular range of holes, and next
through one disc, or several, of wire gauze, fixed a little way below
the wick. The explosive air, after passing up through these wire-gauze
discs, enters a little brass cupola, and is reflected inwards from the
orifice at its top upon the flame, whereby it is completely burned
before it reaches the cavity of the surmounting cylinder. By this
reverberatory action of the air upon the wick, the intensity of the
light is at the same time greatly augmented. Since the feed orifices of
the lamp are small in comparison with the capacity of the surmounting
cage, the latter does not get filled with flame on being plunged in an
explosive gaseous mixture, as happens to the naked cage of Davy. The
wire gauze can never, therefore, become very hot, far less ignited, in
the new lamp. There are, in fact, three impediments to the passage of
the flame out of the lamp; first, the stratum of carbonic acid round
the light; secondly, the wire-gauze cylinder; and thirdly, the glass
cylinder. The entrance at the bottom may be made secure in any desired
degree, by multiplying the layers of wire cloth. The top is protected,
moreover, by a brass hood, through which the currents of carbonic acid
and nitrogen gases, continually ascending from the burning wick, oppose
certain obstacles to the transmission of flame downwards. Even should
the glass be accidentally broken, the lamp is still a complete Davy.

  [49] On the 30th of July, 1835.

In the experiments made before the honourable committee at the London
University, Mr. Pereira showed, first, that when a jet of coal-gas
alone, or an explosive mixture of coal-gas and air, impinged upon the
wire-gauze cylinder of one of Davy’s lamps with a certain force, the
flame generally passed through the meshes, of which there were from 950
to 1024 in the square inch. When a mixture of four parts of hydrogen,
and one of coal-gas was directed in a jet upon the lighted lamps of
Davy, Stevenson, Dillon, Wood of Killingworth (called the refrigerating
lamp), Robson, and Clanny, the flame readily passed; but when thrown
upon the lamp of Upton and Roberts, it did not once pass, causing merely
slight detonations within the lamp. When the force of the jet was
augmented, it extinguished the light. This lamp was finally subjected to
the still severer test of a mixture of four parts of atmospherical air,
and one of hydrogen; yet it did not explode it. When exposed to a
mixture of two-thirds of air, and one of hydrogen, the lamp was
immediately extinguished.

The following, out of many certificates, appears to me decisive in
favour of this improvement of Davy’s lamp. It comes from an experienced
pitman, in a very deep and extensive coal mine, which I know to be
replete with explosive gas, as I have myself visited it in company with
its accomplished engineer, John Buddle, Esq.

“I hereby certify that I have this day tried Messrs. Upton and Roberts’
new patent safety lamp, in the Jarrow colliery; and I state, as an
experienced pitman, having been thirty-two years master wasteman in that
colliery, that I greatly prefer this new lamp to the common Davy lamp. I
had it between five and six hours on trial in the pit. I consider that
it gives about three times the light of the Davy lamp, as I could see at
least ten yards before me in a straight line; and of its great safety I
can have no doubt, as it does not fill with flame, as the Davy does. And
although I had this extra light, there was much less oil consumed. I
consider it a good working lamp.

  “Jarrow Colliery, near Newcastle on Tyne, March 31, 1836.” (Signed)
  “ROBERT FAIRLY.”

[Illustration: 953]

_Fig._ 953., is a vertical section through the middle of the lamp. _a_,
_a_, is the oil-cistern, showing the fold of the wick; it is covered at
top with _b_, _b,_ several layers of wire gauze; _c_, _c_, is the
perforated brass ring, under these layers, for admitting air, which is
reverberated upon the burning wick by the cupola _c_; _d_, _d_, is the
cylinder of glass, surrounding the wire-cloth one; _e_, _e_, is the
safety brass hood, which screws down in the frame, so as to cover in the
top of the glass chimney; _f_, is the arched wire for suspending the
lamp to the girdle of the miner; _g_, is the bent tube for supplying oil
to the cistern; and _h_ is the safety-trimmer, shown more distinctly in
the figure illustrative of the LAMP of DAVY.

Between the glass and the cage there should be a space of about
one-tenth of an inch, forming an annular chimney for the free
ventilation of the flame; and between the under edge of the hood _e_,
and the upper rim of the glass, there should likewise be an interval, as
also vent-holes in the top of the hood, for the free escape of the
smoke. The orifice of the little tube _g_, should be rather lower than
the ring of holes _c_, otherwise the oil, when incautiously poured into
it, might overflow them, and prevent the lamp from burning. _The figure
is drawn somewhat in perspective._

As the naked cage of Davy often gets red-hot with flame; as it is
sometimes used for hours by miners in this most hazardous state; as this
lamp gives so little light as to tempt rash men to remove its
safety-cage;[50] as “it is upon record, that taking the average of ten
years previous to the introduction of Sir H. Davy’s safety lamp, and
allowing one clear year for its introduction, and of ten years after it
was properly introduced, there had been double the number of accidents,
and at least double the number of deaths, of what took place in the ten
years previous to its introduction;[51] as his lamp in explosive
air-courses needs to be carried close upon the bosom, or under the coat
of the miner; as it was declared by its illustrious inventor to be
dangerous when exposed to such currents of explosive gas; and as the
above described modification of it is free from all these defects and
dangers,--I humbly apprehend that no conscientious proprietor or viewer
of coal-mines will delay to substitute the lamp of Upton and Roberts for
the naked Davy, for otherwise he will certainly stand in a very painful
predicament before a coroner’s inquest, at the next mortal casualty from
explosion.”

  [50] At Rowpit Harraton, June 30, 1817, thirty-eight lives were lost
  by the wilfulness of one man unscrewing it, though he was well
  forewarned of the danger. He said, “he could not see with that thing,”
  meaning the Davy.--_Buddle, in Report of House of Commons_, p. 215.

  [51] Dr. Reid Clanny, in Report on Accidents in Mines, p. 32. I
  observe that in Sykes’ _Local Records_ of the counties of Durham and
  Northumberland, corrected by J. Buddle, Esq., there are 540 deaths by
  explosions, between June, 1817, and June, 1835. What a mass of misery
  to the families of the sufferers!

The patentees have, I am told, been put to so much trouble and expense
in trying to introduce this life-protector into our coal-mines, that
they have in a great measure abandoned the business. Messrs. Smith of
Birmingham have meanwhile undertaken to make the lamps.


SAFFLOWER. This dye-stuff has been fully described under CARTHAMUS and
ROUGE.


SAFFRON (_Saffran_, Fr. and Germ.); is a filamentous cake, composed of
the stigmata of the flowers of the _Crocus sativus_. It contains a
yellow matter called _polychroïte_, because a small quantity of it is
capable of colouring a great body of water. This is obtained by
evaporating the watery infusion of saffron to the consistence of an
extract, digesting the extract with alcohol, and concentrating the
alcoholic solution. The polychroïte remains in the form of a brilliant
mass, of a reddish-yellow colour, transparent, and of the consistence of
honey. It has the agreeable smell, with the bitter pungent taste, of
saffron. It is very soluble in water; and if it be stove-dried, it
deliquesces speedily in the air. According to M. Henry _père_,
polychroïte consists of 80 parts of colouring matter, combined with 20
parts of a volatile oil, which cannot be separated by distillation till
the colouring matter has been combined with an alkali. By mixing one
part of shred saffron with eight parts of saturated brine, and one-half
part of caustic lye, and distilling the mixture, the oil comes over into
the receiver, and leaves the colouring matter in the retort, which may
be precipitated from the alkaline solution by an acid. The pure
colouring matter, when dried, is of a scarlet hue, and then readily
dissolves in alcohol, as also in the fat and volatile oils, but
sparingly in water. Light blanches the reddish-yellow of saffron, even
when it is contained in a full phial well corked. Polychroïte, when
combined with fat oil, and subjected to dry distillation, affords
ammonia, which shows that azote is one of its constituents. Sulphuric
acid colours the solution of polychroïte indigo blue, with a lilac cast;
nitric acid turns it green, of various shades, according to the state of
dilution. Protochloride (muriate) of tin produces a reddish precipitate.

Saffron is employed as a seasoning in French cookery. It is also used to
tinge confectionary articles, liqueurs, and varnishes; but rarely as a
pigment.


SAGO (_Sagou_, Fr. and Germ.); is a species of starch, extracted from
the pith of the sago palm, a tree which grows to the height of 30 feet
in the Moluccas and the Philippines. The tree is cut down, cleft
lengthwise, and deprived of its pith, which being washed with water upon
a sieve, the starchy matter comes out, and soon forms a deposit. This is
dried to the consistence of dough, pressed through a metal sieve to corn
it (which is called _pearling_), and then dried over a fire with
agitation in a shallow copper pan. Sago is sometimes imported in the
pulverulent state, in which it can be distinguished from arrow-root only
by microscopic examination of its particles. These are uniform and
spherical, not unequal and ovoid, like those of arrow-root.


SAL AMMONIAC. The manufacture of this salt may be traced to the remotest
era. Its name is derived from Ammonia, or the temple of Jupiter Ammon,
in Egypt, near to which the salt was originally made. Sal ammoniac
exists ready formed in several animal products. The dung and urine of
camels contain a sufficient quantity to have rendered its extraction
from them a profitable Egyptian art in former times, in order to supply
Europe with the article. In that part of Africa, fuel being very scarce,
recourse is had to the dung of these animals, which is dried for that
purpose, by plastering it upon the walls. When this is afterwards burned
in a peculiar kind of furnace, it exhales a thick smoke, replete with
sal ammoniac in vapour; the soot of course contains a portion of that
salt, condensed along with other products of combustion. In every part
of Egypt, but especially in the Delta, peasants are seen driving asses
loaded with bags of that soot, on their way to the sal ammoniac works.

Here it is extracted in the following manner. Glass globes coated with
loam are filled with the soot pressed down by wooden rammers, a space of
only two or three inches being left vacant, near their mouths. These
globes are set in round orifices formed in the ridge of a long vault, or
large horizontal furnace flue. Heat is gradually applied by a fire of
dry camels’ dung, and it is eventually increased till the globes become
obscurely red. As the muriate of ammonia is volatile at a temperature
much below ignition, it rises out of the soot in vapour, and gets
condensed into a cake upon the inner surface of the top of the globe. A
considerable portion, however, escapes into the air; and another portion
concretes in the mouth, which must be cleared from time to time by an
iron rod. Towards the end, the obstruction becomes very troublesome, and
must be most carefully attended to and obviated, otherwise the globes
would explode by the uncondensed vapours. In all cases, when the
subliming process approaches to a conclusion, the globes crack or split;
and when they come to be removed, after the heat has subsided, they
usually fall to pieces. The upper portion of the mass is separated,
because to it the white salt adheres; and on detaching the pieces of
glass with a hatchet, it is ready for the market. At the bottom of each
balloon a nucleus of salt remains, surrounded with fixed pulverulent
matter. This is reserved, and after being bruised, is put in along with
the charge of soot in a fresh operation.

The sal ammoniac obtained by this process is dull, spongy, and of a
grayish hue; but nothing better was for a long period known in commerce.
Forty years ago, it fetched 2_s._ 6_d._ a pound; now, perfectly pure sal
ammoniac may be had at one-fifth part of that price.

Various animal offals develope during their spontaneous putrefactive
fermentation, or their decomposition by heat, a large quantity of free
or carbonated ammonia, among their volatile products. Upon this
principle many sal ammoniac works have been established. In the
destructive distillation of pitcoal, there is a considerable quantity of
ammoniacal products, which are also worked up into sal ammoniac.

The first attempts made in France to obtain sal ammoniac profitably in
this manner, failed. A very extensive factory of the kind, which
experienced the same fate, was under the superintendence of the
celebrated Baumé, and affords one out of a thousand instances where
theoretical chemists have shown their total incapacity for conducting
operations on the scale of manufacturing economy. It was established at
Gravelle near Charenton, and caused a loss to the shareholders in the
speculation of upwards of 400,000 francs. This result closed the concern
in 1787, after a foolish manipulation of 27 years. For ten years after
that event, all the sal ammoniac consumed in France was imported into it
from foreign countries. Since then the two works of MM. Payen and
Pluvinet were mounted, and seem to have been tolerably successful. Coal
soot was, prior to the introduction of the gas-works, a good deal used
in Great Britain for obtaining sal ammoniac. In France, bones and other
animal matters are distilled in large iron retorts, for the manufacture
of both animal charcoal and sal ammoniac.

[Illustration: 954 955]

These retorts are iron cylinders, 2 or 3 feet in diameter, and 6 feet
long. _Figs._ 954. and 955. show the form of the furnace, and the manner
in which the cylinders are arranged; the first being a longitudinal, the
second a transverse section of it. A, the ash-pits under the grates; B,
the fireplaces, arched over at top; C, the vault or bench of
fire-bricks, perforated inside with eight flues for distributing the
flame; D, a great arch, with a triple voussoir D, _d´_, _d´´_, under
which the retorts are set. The first arch D, is perforated with twenty
vent-holes; the second, with four vent-holes; through which the flame
passes to the third arch, and thence to the common chimney-stalk. The
retorts _e_, are shut by the door _e´_ (_fig._ 955.), luted, and made
fast with screw-bolts. Their other ends _e´´_ terminate in tubes _f_,
_f_, _f_, which all enter the main pipe _h_. The condensing pipe
proceeds slantingly downwards from the further end of _h_, and dips into
a large sloping iron cylinder immersed in cold water. See GAS-LIGHT and
STOVE, for a better plan of furnace.

[Illustration: 956]

The filters used in the large sal ammoniac works in France are
represented in _fig._ 956. The apparatus consists----1. of a wooden
chest _a_, lined with lead, and which is turned over at the edges; a
socket of lead _b_, soldered into the lowest part of the bottom, serves
to discharge the liquid; 2. of a wooden crib or grating formed of
rounded rods, as shown in the section _c_, _c_, and the plan _d_; this
grating is supported one inch at least above the bottom, and set truly
horizontal, by a series of wedges; 3. of an open fabric of canvas or
strong calico, laid on the grating, and secured over the edges, so as to
keep it tense. A large wooden reservoir _f_, lined with lead, furnished
with a cover, is placed under each of the filters; a pump throws back
once or twice upon the filters what has already passed through. A common
reservoir _g_, below the others, may be made to communicate at pleasure
with one of them, by means of intermediate stopcocks.

The two boilers for evaporating and decomposing are made of lead, about
one quarter of an inch thick, set upon a fire-brick vault, to protect
them from the direct action of the flame. Through the whole extent of
their bottoms above the vault, horizontal cast-iron plates, supported by
ledges and brick compartments, compel the flame and burned air, as they
issue from the arch, to percur many sinuosities before they pass up the
chimney. This floor of cast iron is intended to support the bottom of
the boiler, and to diffuse the heat more equably. The leaden boilers are
surrounded with brickwork, and supported at their edges with a wooden
frame. They may be emptied at pleasure into lower receivers, called
crystallizers, by means of leaden syphons and long-necked funnels.

The crystallizers are wooden chests lined with lead, 15 inches deep, 3
or 4 feet broad, and from 6 to 8 feet long; and may be inclined to one
side at pleasure. A round cistern receives the drainings of the
mother-waters. The pump is made of lead, hardened with antimony and tin.

[Illustration: 957 958 959 960 961]

The subliming furnace is shown in _figs._ 957. and 958. by a transverse
and longitudinal section. _a_ is the ash-pit; _b_, the grate and
fireplace; _c_, the arch above them. This arch, destined to protect the
bottles from the direct action of the fire, is perforated with
vent-holes, to give a passage to the products of combustion between the
subliming vessels. _d_, _d_, are bars of iron, upon which the bottoms of
the bottles rest; _e_, stoneware bottles, protected by a coating of loam
from the flame.

_Fig._ 959. shows the cast-iron plates, _a_, _b_, _c_, which, placed
above the vaults, receive each two bottles in a double circular opening.

At the extremity of the above furnace, a second one, called the drier,
_fig._ 960., receives the products of the combustion of the first, at A,
under horizontal cast-iron plates, and upon which the bottom of a rather
shallow boiler B, rests. After passing twice under these plates, round a
longitudinal brick partition _b_, _b´_, _b´´_, the products of
combustion enter the smoke chimney C. See plan, _fig._ 961.

The boiler set over this furnace should have no soldered joints. It may
be 3-1/2 feet broad, 9 or 10 feet long, and 1 foot deep. The concrete
sal ammoniac may be crushed under a pair of edge mill-stones, when it is
to be sold in powder.

Bones, blood, flesh, horns, hoofs, woollen rags, silk, hair, scrapings
of hides and leather, &c., may be distilled for procuring ammonia. When
bones are used, the residuum in the retort is bone black. The charcoal
from the other substances will serve for the manufacture of prussian
blue. The bones should undergo a degree of calcination beyond what the
ammoniacal process requires, in order to convert them into the best bone
black; but the other animal matters should not be calcined up to that
point, otherwise they are of little use in the prussian blue works. If
the bones be calcined, however, so highly as to become glazed, their
decolouring power on syrups is nearly destroyed. The other substances
should not be charred beyond a red-brown heat.

The condensed vapours from the cylinder retorts afford a compound liquor
holding carbonate of ammonia in solution, mixed with a large quantity of
empyreumatic oil, which floats at top. Lest incrustations of salt should
at any time tend to obstruct the tubes, a pipe should be inserted within
them, and connected with a steam boiler, so as to blow steam through
them occasionally.

The whole liquors mixed have usually a density of 8° or 9° Baumé
(1·060). The simplest process for converting their carbonate of ammonia
into muriate, is to saturate them with muriatic acid, to evaporate the
solution in a leaden boiler till a pellicle appears, to run it off into
crystallizers, and to drain the crystals. Another process is, to
decompose the carbonate of ammonia, by passing its crude liquor through
a layer of sulphate of lime, 3 or 4 inches thick, spread upon the
filters, _fig._ 956. The liquor may be laid on with a pump; it should
never stand higher than 1 or 2 inches above the surface of the bruised
gypsum, and it should be closely covered with boards, to prevent the
dissipation of the volatile alkali in the air. When the liquor has
passed through the first filter, it must be pumped upon the second; or
the filters being placed in a terrace form, the liquor from the first
may flow down upon the second, and thus in succession. The last filter
should be formed of nearly fresh gypsum, so as to ensure the thorough
conversion of the carbonate into sulphate. The resulting layers of
carbonate of lime should be washed with a little water, to extract the
sulphate of ammonia interposed among its particles. The ammoniacal
liquor thus obtained must be completely saturated, by adding the
requisite quantity of sulphuric acid; even a slight excess of acid can
do no harm. It is then to be evaporated, and the oil must be skimmed off
in the course of the concentration. When the liquid sulphate has
acquired the density of about 1·160, sea salt should be added, with
constant stirring, till the whole quantity equivalent to the double
decomposition be introduced into the lead boiler.

The fluid part must now be drawn off by a syphon into a somewhat deep
reservoir, where the impurities are allowed to subside; it is then
evaporated by boiling, till the sulphate of soda falls down in granular
crystals, as the result of the mutual reaction of the sulphate of
ammonia and muriate of soda; while the more soluble muriate of ammonia
remains in the liquor. During this precipitation, the whole must be
occasionally agitated with wooden paddles; the precipitate being in the
intervals removed to the cooler portion of the pan, in order to be taken
out by copper rakes and shovels, and thrown into draining-hoppers,
placed near the edges of the pan. The drained sulphate of soda must be
afterwards washed with cold water, to extract all the adhering sal
ammoniac.

The liquor thus freed from the greater part of the sulphate, when
sufficiently concentrated, is to be drawn off by a lead syphon, into the
crystallizers, where, at the end of 20 or 30 hours, it affords an
abundant crop of crystals of sal ammoniac. The mother-water may then be
run off, the crystallizers set aslope to drain the salt, and the salt
itself must be washed, first by a weak solution of sal ammoniac, and
lastly with water. It must be next desiccated, by the apparatus _fig._
960., into a perfectly dry powder, then put into the subliming stoneware
balloons, by means of a funnel, and well rammed down. The mouth of the
bottle is to be closed with a plate or inverted pot of any kind. The
fire must be nicely regulated, so as to effect the sublimation of the
pure salt from the under part of the bottle, with due regularity, into a
white cake in the upper part. The neck of the bottle should be cleared
from time to time with a long steel skewer, to prevent the risk of
choking, and consequent bursting; but in spite of every precaution,
several of the bottles crack almost in every operation. In Scotland, sal
ammoniac is sublimed in cast-iron pots lined with thin fire-tiles, made
in segments accommodated to the internal surface of the pots; the vapour
being received and condensed into cakes, within balloons of green glass
set over their mouths. The salt, when taken out, and freed by scraping
from any adhering ochreous or other impurities, is ready for the market,
being sold in hollow spherical masses. The residuum in the pots or
bottles may be partially worked up in another operation. The greatest
evil is produced by the mixture or even contact of iron, because its
peroxide readily rises in vapour with the sal ammoniac, and tinges it of
a red or yellow colour.

The most ordinary process for converting the ammoniacal liquor of the
gas works into sal ammoniac, is to saturate it with sulphuric acid, and
to decompose the sulphate, thus formed, by the processes above
described. But muriatic acid will be preferred, where it is as cheap as
sulphuric of equivalent saturating power; because a tolerably pure sal
ammoniac is thereby directly obtained. As the coal-gas liquor contains a
good deal of sulphuretted hydrogen, the saturation of it with acid
should be so conducted as to burn the disengaged noxious gases in a
chimney. Formerly human urine was very extensively employed, both in
this country and in France, in the manufacture of sal ammoniac; but
since the general establishment of gas-works it has been, I believe,
abandoned. The process was exceedingly offensive.

The best white sal ammoniac is in spheroidal cakes of about one foot
diameter, three or four inches thick in the middle, somewhat thinner at
the edges, and is semi-transparent or translucent. Each lump weighs
about one quarter of a cwt. As it is easily volatilized by heat, it may
be readily examined as to its sophistication with other salts. Sal
ammoniac has a certain tenacity, and is flexible under the hammer or
pestle. It is principally used in tinning of cast-iron, wrought iron,
copper, brass, and for making the various ammoniacal preparations of
pharmacy.

In a chemical factory near Glasgow, 7200 gallons of ammoniacal liquor,
obtained weekly from the gas-works, are treated as follows:--The liquor
is first rectified by distillation from a waggon-shaped wrought-iron
boiler, into a square cistern of iron lined with lead. 4500 lbs. of
sulphuric acid, of specific gravity 1·625, are then slowly added to the
somewhat concentrated distilled water of ammonia. The produce is 2400
gallons of sulphate of ammonia, slightly acidulous, of specific gravity
1·150, being of such strength as to deposit a few crystals upon the
sides of the lead-lined iron tank in which the saline combination is
made. It is decomposed by common salt.

From the 7200 gallons of the first crude liquor, 900 gallons of tar are
got by subsidence, and 200 gallons of petroleum are skimmed off the
surface. The tar is converted, by a moderate boiling in iron pans, into
good pitch.


SALAMSTONE. See LAPIDARY.


SALEP, or SALOUP, is the name of the dried tuberous roots of the
_Orchis_, imported from Persia and Asia Minor, which are the product of
a great many species of the plant, but especially of the _Orchis
mascula_. Salep occurs in commerce in small oval grains, of a
whitish-yellow colour, at times semi-transparent, of a horny aspect,
very, hard, with a faint peculiar smell, and a taste like that of gum
tragacanth, but slightly saline. These are composed almost entirely of
starchy matter, well adapted for making a thick pap with water or milk,
and are hence in great repute in the Levant, as restorers of the animal
forces. Their aphrodisiacal properties are apocryphal. If the largest
roots of the _Orchis mascula_ of our own country were cleaned, scraped,
steeped for a short time in hot, and then for a few minutes in boiling
water, to extract their rank flavour, afterwards suspended upon strings
to dry in the air, they would afford as nourishing and palatable an
article as the Turkey saloup, and at a vastly lower price.


SALICINE, is a febrifuge substance, which may be obtained in white
pearly crystals from the bark of the white willow (_Salix alba_), of the
aspen tree (_Salix helix_), as also of some other willows, and some
poplars. It has a very bitter taste.


SAL PRUNELLA, is fused nitre cast into cakes or balls.


SAL VOLATILE, is sesquicarbonate of ammonia.


SALT, EPSOM, is sulphate of magnesia.


SALT, MICROCOSMIC, is the triple phosphate of soda and ammonia.


SALT OF AMBER, is succinic acid.


SALT OF LEMONS, is citric acid.


SALT OF SATURN, is acetate of lead.


SALT OF SODA, is carbonate of soda.


SALT OF SORREL, is bi-oxalate of potassa.


SALT OF TARTAR, is carbonate of potassa.


SALT OF VITRIOL, is sulphate of zinc.


SALT PERLATE, is phosphate of soda.


SALTPETRE, is nitre, or nitrate of potassa.


SALT, SEDATIVE, is boracic acid.


SALTS, are an important class of chemical compounds, antiently studied
under the Greek title of _Halurgy_. At one period every inorganic
substance readily soluble in water, was regarded as a salt; and
afterwards, every substance soluble in five hundred times its weight of
water. Thus both acid and alkaline bodies came to be enrolled among
salts; but latterly, the combinations of the acids with alkalis, earths,
and metallic calces (now styled oxides), were alone thought to be
entitled to the denomination of salts, in consequence of their
resemblance in appearance, and supposed analogy in composition, to
culinary salt. Since Sir H. Davy demonstrated that this substance
contained neither acid nor alkaline matter, but that it consisted of
chlorine and the metal sodium, the generality of chemists found it
impossible to include salts under one category of constitution; while a
few have rashly offered to cut the knot, by excluding from the saline
family, chloride of sodium, the patriarch of the whole.

_Salts_, may be justly divided into three orders:

1. The binary, consisting of two single members; such as the bromides,
chlorides, cyanides, fluorides, iodides, carburets, phosphurets,
sulphurets, &c.

2. The bi-binary, consisting of two double members; such as the borates,
bromates, carbonates, chlorates, sulphates, sulphites, hyposulphites,
sulphohydrates, &c.

3. The ternary, consisting of two single members of one genus, and one
member of another; such as the boro-fluorides, silico-fluorides,
sulpho-cyanides, chloriodides, &c.

The species of each order may exist in three states, constituting
neutral salts; supersalts; and subsalts; as for example, the chloride of
sodium, the bisulphate of potassa, the subnitrate of lead, &c.

In the above arrangement, cyanogen is allowed to represent a simple
substance, from its forming analogous compounds with chlorine and
iodine. The neutral state of salts is commonly indicated by their
solutions not changing the colours of litmus, violets, or red cabbage;
the sub-state of salts, by their turning the violet and cabbage green;
and the super-state of salts, by their changing the purple of litmus,
violets, and cabbage, red; but to the generality of this criterion there
are some exceptions. The atomic theory may be advantageously resorted
to, in this predicament. 1. When one prime equivalent of the one member
(whether single or double) of a salt, combines with one prime of the
other member, a neutral salt is the result, as in chloride of sodium or
nitrate of potassa. 2. When two primes of the electro-negative member
combine with one prime of the electro-positive, a supersalt is formed,
as bichloride of tin, or bisulphate of potassa. 3. When one prime of the
electro-negative member combines with two or more primes of the
electro-positive, a subsalt is produced, as the subacetate and
subchromate of lead, &c.


SALT, SEA, or CULINARY; _Chloride of sodium_; _muriate of soda_.
(_Hydrochlorate de soude_, Fr.; _Chlornatrium_, Germ.) Sea salt, or rock
salt, in a state of purity, consists of 60 of chlorine + 40 of sodium,
in 100 parts.

This important species of the saline class possesses, even in mass, a
crystalline structure, derived from the cube, which is its primitive
form. It has generally a foliated texture, and a distinct cleavage; but
it has also sometimes a fibrous structure. The massive salt has a
vitreous lustre. It is not so brittle as nitre; it is nearly as hard as
alum, a little harder than gypsum, and softer than calcareous spar. Its
specific gravity varies from 2·0 to 2·25. When pure, it is colourless,
translucent, or transparent. On exposure to heat, it commonly
decrepitates; but some kinds of rock salt enter quietly into fusion at
an elevated temperature, a circumstance which has been ascribed to their
having been originally subjected to the action of fire.

According to M. Gay Lussac, 100 parts of water dissolve--

  35·81 parts of the salt, at temperature  57·0° Fahr.
  35·88                 --                 62·5°
  37·14                 --                140·0°
  40·38                 --                229·5°

Native chloride of sodium, whether obtained from the waters of the
ocean, from saline lakes, from salt springs, or mineral masses, is never
perfectly pure. The foreign matters present in it vary with its
different origins and qualities. These are, the sulphates of lime,
magnesia, soda, muriates of magnesia and potash, bitumen, oxide of iron,
clay in a state of diffusion, &c.

Muriate of potash has been detected, in the waters of the ocean, in the
sal-gem of Berchtesgaden in Bavaria, of Hallein in the territory of
Salzbourg, and in the salt springs of Rosenheim.

The more heterogeneous the salt, the more soluble is it, by the
reciprocal affinity of its different saline constituents; and thus a
delicate hydrometer, plunged in saturated brine, may serve to show
approximately the quality of the salt. I find that the specific gravity
of a saturated solution of large-grained cubical salt, is 1·1962 at 60°
F. 100 parts of this brine contain 25-1/2 of salt, (100 w. + 34·2 s.)
From mutual penetration, 100 volumes of the aqueous and saline
constituents form rather less than 96 of the solution.

Among the varieties in the form of this salt, the octahedral, the
cubo-octahedral, and the dodecahedral, have been mentioned; but there is
another, called the funnel or hopper-shaped, which is very common. It is
a hollow rectangular pyramid, which forms at the surface of the saline
solution in the course of its evaporation, commencing with a small
floating cube, upon which lines of other little cubes attach themselves
to the edges of the upper face; whereby they form and enlarge the sides
of a hollow pyramid, whose apex, the single cubic crystal, is downward.
This sinks by degrees as the aggregation goes on above, till a pyramidal
boat of considerable size is constructed.

A TABLE of the results of the ANALYSES of several varieties of CULINARY
SALT.

  +--------------------+-----+-----+-----+-----+-----+-----+-----+-----+
  |Origin of the Salt. |Chlo-|Muri-|Muri-|Sul- |Sul- |Sul- |Clay |Oxide|
  |                    |ride |ate  |ate  |phate|phate|phate|and  |of   |
  |                    |of   |of   |of   |of   |of   |of   |other|Iron.|
  |                    |Sodi-|Mag- |Lime.|Soda.|Mag- |Lime.|in-  |     |
  |                    |um.  |ne-  |     |     |ne-  |     |solu-|     |
  |                    |     |sia. |     |     |sia. |     |ble  |     |
  |                    |     |     |     |     |     |     |bod- |     |
  |                    |     |     |     |     |     |     |ies. |     |
  +--------------------+-----+-----+-----+-----+-----+-----+-----+-----+
  |Sal-gem of Vic{white|99·30| --  | --  | --  | --  |0·005|0·020|     |
  |              {red  |99·80| --  | --  | --  | --  | --  |0·002|     |
  |---------- Cheshire,|     |     |     |     |     |     |     |     |
  |           crushed  |98·33|0·02 | --  | --  | --  |0·65 | --  |0·002|
  |                    |     |     |     |     |     |     |     |     |
  |_Salt from Salt_    |     |     |     |     |     |     |     |     |
  |_Springs_:          |     |     |     |     |     |     |     |     |
  |Schönbeck, West-    |     |     |     |     |     |     |     |     |
  |phalia              |93·90|0·30 | --  |1·00 | --  |0·80 |     |     |
  |Moutiers {des cordes|97·17|0·25 | --  |2·00 |0·58 |     |     |     |
  |         {boilers   |93·59|0·61 | --  |5·55 |0·25 |     |     |     |
  |Château Salins      |97·82|2·12 |     |     |     |     |     |     |
  |White of Sulz       |96·88|3·12 |     |     |     |     |     |     |
  |Ludwigshall, middle |     |     |     |     |     |     |     |     |
  |grained             |99·45| --  | --  |0·05 | --  |0·28 |     |     |
  |Kœnigsborn, West-   |     |     |     |     |     |     |     |     |
  |phalia              |95·90| --  |0·27 | --  | --  |1·10 |     |     |
  |                    |     |     |     |     |     |     |     |     |
  |Sea salt, half white|97·20|0·004| --  | --  |0·050|0·120|0·070|     |
  |--------, of Saint  |     |     |     |     |     |     |     |     |
  |Malo                |96·  |0·30 | --  | --  |0·45 |2·35 |     |     |
  |Common Scottish salt|93·55|2·80 | --  | --  |1·75 |1·50 |     |     |
  |Lymington, common   |93·7 | 1·1 | --  | --  |3·50 |1·50 |2·00 |     |
  |---------, cat      |98·8 | 0·5 | --  | --  |0·5  |0·1  |     |     |
  |Cheshire, stoved    |98·25|0·075|0·025| --  | --  |1·55 |     |     |
  +--------------------+-----+-----+-----+-----+-----+-----+-----+-----+

The geological position of rock salt is between the coal formation and
the lias. The great rock-salt formation of England occurs within the
_red marl_, or new red sandstone, the _bunter-sandstein_ of the Germans,
so called, because its colours vary from red to salmon and chocolate.
This mineral stratum frequently presents streaks of light blue,
verdigris, buff, or cream colour; and is chiefly remarkable for
containing considerable masses or beds of gypsum. At Northwich, in the
vale of the Weaver, the rock salt consists of two beds, together not
less than 60 feet thick, which are supposed to constitute large
insulated masses, about a mile and a half long, and nearly 1300 yards
broad. There are other deposits of rock salt in the same valley, but of
inferior importance. The uppermost bed occurs at 75 feet beneath the
surface, and is covered with many layers of indurated red, blue, and
brown clay, interstratified more or less with sulphate of lime, and
interspersed with argillaceous marl. The second bed of rock salt lies
31-1/2 feet below the first, being separated from it by layers of
indurated clay, with veins of rock salt running through them. The lowest
bed of salt was excavated to a depth of 110 feet, several years ago.

The beds or masses of rock salt are occasionally so thick, that they
have not been yet bored through, though mined for many centuries. This
is the case with the immense mass of Wieliczka, and the lower bed at
Northwich. But in ordinary cases, this thickness varies from an inch or
two to 12 or 15 yards. When the strata are thin, they are usually
numerous; but the beds, layers, or masses never exhibit throughout a
great extent any more than an illusory appearance of parallelism; for
when they are explored at several points, enlargements are observed, and
such diminutions as cause the salt to disappear sometimes altogether.
This mineral is not deposited, therefore, in a geological stratum, but
rather in lenticular masses, of very variable extent and thickness,
placed alongside of each other at unequal distances, and interposed
between the courses of the other formations.

Sometimes the rock salt is disseminated in small masses or little veins
among the calcareous and argillaceous marls which accompany or overlie
the greater deposits. Bitumen, in small particles, hardly visible, but
distinguishable by the smell, occurs in all the minerals of the
saliferous system.

It has been remarked, that the plants which grow generally on the sea
shores, such as the _Triglochinum maritimum_, the _Salicornia_, the
_Salsola kali_, the _Aster trifolium_, or farewell to summer, the _Glaux
maritima_, &c., occur also in the neighbourhood of salt mines and salt
springs, even of those which are most deeply buried beneath the surface.

The interior of rock-salt mines, after digging through the strata of
clay marl, &c. is extremely dry; so that the dust produced in the
workings becomes an annoyance to the miners, though in other respects
the excavations are not at all insalubrious.

Salt springs occur nearly in the same circumstances, and in the same
geological formation as the salt rock. It has been noticed that salt
springs issue, in general, from the upper portion of the saliferous
strata, principally from the saline clay marls. Cases however occur,
where the salt springs are not accompanied by rock salt, and where the
whole saline matter is derived from the marls themselves, which thus
constitute the only saliferous beds.

It has been imagined that there are two other periods of geological
formation of this substance; one much more antient, belonging to the
transition series of rocks; the other relatively modern, among secondary
strata. To the former has been referred the salt formation of Bex, that
of Cardonne, &c. But M. Brongniart assigns valid reasons for rejecting
this supposition. M. Beudant, indeed, refers to the secondary strata
above the chalk, the rock-salt formation of Wieliczka, and of the base
of the Carpathians; placing these among the plastic clay and lignites.

The mines of rock salt do not appear to possess any determinate
elevation upon the surface of the earth. Immense masses of it are met
with at very great depths below the level of the sea, (the mine of
Wieliczka is excavated 860 feet beneath the soil,) and others exist at a
considerable altitude, as that of Hallein near Salzbourg, which is 3300
feet above the level of the sea, and the saline rock of Arbonne in
Savoy, which is nearly 4000 feet higher, situated at the great elevation
of 7200 feet above the level of the sea, and consequently in the region
of perpetual snow. The rock is a mass of saccharoid and anhydrous
gypsum, imbued with common salt, which is extracted by lixiviation;
after which the gypsum remains porous and light.

The inland seas, salt lakes, and salt marshes, have their several
localities obviously independent of peculiar geological formations. The
ocean is, however, the most magnificent mine of salt, since this
chloride constitutes about one-thirtieth part of its weight; being
pretty evenly diffused throughout its waters, when no local cause
disturbs the equilibrium. The largest proportion of salt held in
solution in the open sea, is 38 parts in 1000, and the smallest 32. In a
specimen taken by Mr. Wilkinson, out of the Red Sea, at Berenice, I
found 43 parts of salt in 1000. The specific gravity of the water was
1·035.

Were it requisite to extract the chloride of sodium from sea-water by
fuel alone, many countries, even maritime, would find the process too
costly. The salt is therefore obtained from it in two different manners;
1. by natural evaporation alone; 2. by natural and artificial
evaporation combined. The first method is employed in warm regions,
under the form of saline tanks, or brine reservoirs, called also
brine-pits. These are large shallow basins, the bottom of which is very
smooth, and formed of clay. They are excavated along the sea-shore, and
consist of----

1st. A large reservoir, deeper than the proper brine-pits, which is dug
between them and the sea. This reservoir communicates with the sea by
means of a channel provided with a sluice. On the sea-shore, these
reservoirs may be filled at high water, though the tides are rather
inconvenient than advantageous to brine-pits.

2dly. The brine-pits, properly so called, which are divided into a
number of compartments by means of little banks. All these compartments
have a communication with each other, but so that the water frequently
has a long circuit to make, from one set to another. Sometimes it must
flow 400 or 500 yards, before it reaches the extremity of this sort of
labyrinth. The various divisions have a number of singular names, by
which they are technically distinguished. They should be exposed to the
north, north-east, or north-west winds.

The water of the sea is let into these reservoirs in the month of March,
where it is exposed on a vast surface to evaporation. The first
reservoir is intended to detain the water till its impurities have
subsided, and from it the other reservoirs are supplied, as their water
evaporates. The salt is considered to be on the point of crystallizing
when the water begins to grow red. Soon after this, a pellicle forms on
the surface, which breaks, and falls to the bottom. Sometimes the salt
is allowed to subside in the first compartment; at others, the strong
brine is made to pass on to the others, where a larger surface is
exposed to the air. In either case the salt is drawn out, and left upon
the borders to drain and dry.

The salt thus obtained, partakes or the colour of the bottom on which it
is formed; and is hence white, red, or gray.

Sea water contains, in 1000 parts, 25 of chloride of sodium, 5·3
sulphate of magnesia, 3·5 chloride of magnesium, 0·2 carbonate of lime
and magnesia, 0·1 sulphate of lime, besides 1/2000 of sulphate and
muriate of potash. It also contains iodide of sodium, and bromide of
magnesium. Its average spec. grav. is from 1·029 to 1·030.

[Illustration: 962 963 964]

Sea-water and weak brines may be concentrated either by the addition of
rock salt, by spontaneous evaporation in brine-pits (see _suprà_), or by
graduation. Houses for the last purpose are extensively employed in
France and Germany. The weak brine is pumped into an immense cistern on
the top of a tower, and is thence allowed to flow down the surface of
bundles of thorns built up in regular walls, between parallel wooden
frames. At Salza, near Schönebeck, the graduation-house is 5817 feet
long, the thorn walls are from 33 to 52 feet high, in different parts,
and present a total surface of 25,000 square feet. Under the thorns, a
great brine cistern, made of strong wooden planks, is placed, to receive
the perpetual shower of water. Upon the ridge of the graduation-house
there is a long spout, perforated on each side with numerous holes, and
furnished with spigots or stopcocks for distributing the brine, either
over the surface of the thorns, or down through their mass; the latter
method affording larger evaporation. The graduation-house should be
built lengthwise in the direction of the prevailing wind, with its ends
open. An experience of many years at Salza and Dürrenberg has shown,
that in the former place graduation can go on 258, and in the latter 207
days, on an average, in the year; the best season being from May till
August. At Dürrenberg, 3,596,561 cubic feet of water are evaporated
annually. According to the weakness of the brine, it must be the more
frequently pumped up, and made to flow down over the thorns in different
compartments of the building, called the 1st, 2d, and 3d graduation. A
deposit of gypsum incrusts the twigs, which requires them to be renewed
at the end of a certain time. _Figs._ 962. and 963. represent the
graduation-house of the salt-works at Dürrenberg. _a_, _a_, _a_, are low
stone pillars for supporting the brine cistern _b_, called the
_soole-schiff_. _c_, _c_ are the inner, _d_, _d_ the outer, walls of
thorns; the first have perpendicular sides, the last sloping. The spars
_e_, _e_, which support the thorns, are longer than the interval between
two thorn walls from _f_ to _g_, _fig._ 963, whereby they are readily
fastened by their tenons and mortises. The spars are laid at a slope of
2 inches in the foot, as shown by the line _h_, _i_. The bundles of
thorns are each 1-1/2 foot thick, from 5 to 7 feet long, and are piled
up in the following way:----Guide-bars are first placed in the line _k_,
_l_, to define the outer surface of the thorn wall, the undermost spars
_m_, _n_, are fastened upon them; and the thorns are evenly spread,
after the willow-withs of the bundles have been cut. Over the top of the
thorn walls are laid, through the whole length of the graduation-house,
the brine spouts _o_, _o_, which are secured to the upper beams; and at
both sides of these spouts are the drop-spouts _p_, _p_, for discharging
the brine by the spigots _s_, _s_, as shown upon a larger scale in
_fig._ 964. The drop-spouts are 6 feet long, have on each side small
notches, 5 inches apart, and are each supplied by a spigot. The space
above the ridge of the graduation-house is covered with boards,
supported at their ends by binding-beams _q_. _r_, _r_ show the tenons
of the thorn-spars. Over the soole schiff _b_, inclined planes of boards
are laid for conducting downwards the innumerable showers. The brine,
which contains at first 7·692 per cent. of salt, indicates, after the
first shower, 11·473; after the second, 16·108; and after the third, 22.
The brine, thus concentrated to such a degree as to be fit for boiling,
is kept in great reservoirs, of which the eight at Salza, near
Schönebeck, have a capacity of 2,421,720 cubic feet, and are furnished
with pipes leading to the sheet-iron salt-pans. The capacity of these is
very different at different works. At Schönebeck there are 22, the
smallest having a square surface of 400 feet, the largest of 1250, and
are enclosed within walls, to prevent their being affected by the cold
external air. They are covered with a funnel-formed or pyramidal trunk
of deals, ending in a square chimney, to carry off the steam.

[Illustration: 965 966 967]

_Figs._ 965, 966, 967. represent the construction of a salt-pan, its
furnace, and the salt store-room of the works at Dürrenberg; _fig._ 967.
being the ground plan, _fig._ 966. the longitudinal section, and _fig._
965. the transverse section, _a_ is the fire-grate, which slopes upwards
to the back part, and is 31-1/2 inches distant from the bottom of the
pan. The ratio of the surface of the grate to that of the bottom of the
pan, is as 1 to 59·5; that of the air-hole into the ash-pit, as 1 to
306. The bed under the pan is laid with bricks, smoothly plastered over,
from _b_ to _c_, in _fig._ 966. Upon this bed the pillars _d_, _d_, &c.,
are built in a radiated direction, being 6 inches broad at the bottom,
and tapering to 1-1/2 inch at top. The pan is so laid that its bottom
has a fall towards the middle of 2-1/2 inches: see _e_, _f_, _fig._ 966.
The fire diffuses itself in all directions under the pan, proceeds
thence through several holes _g_, _g_, _g_, into flues _h_, _h_, _h_,
which run round three sides of the pan; the burnt air then passes
through _i_, _fig._ 967., under other pans, from which it is collected
in the chimneys _k_, _k_, to be conducted into the drying-room. At _l_,
_l_, there is a transverse flue, through which, by means of dampers, the
fire-draught may be conducted into an extra chimney _m_. From the flues
_k_, _k_, four square iron pipes _n_, _n_, issue and conduct the burnt
air into the main chimneys in the opposite wall.

The bottoms of the several flues have a gradual ascent above the level
of the fire-grate. A special chimney _o_, rises above the ash-pit, to
carry off the smoke, which may chance to regurgitate in certain states
of the wind. _p_, _p_, are iron pipes laid upon each side of the ash-pit
(see _figs._ 966. and 967.), into which cold air is admitted by the flue
_q_, _r_, where, becoming heated, it is conducted through iron pipes
_s_, and thence escapes at _t_, into the stove-room. Upon both sides of
the hot flues in the stove-room, hurdle-frames _u_, _u_, are laid, each
of which contains 11 baskets, and every basket, except the undermost,
holds 60 pounds of salt, spread in a layer 2 inches thick. _v_, _v_,
show the pipes by which the pan is supplied with graduated brine.

_Description of the Steam-trunk, in fig. 968._

[Illustration: 968]

In front of the pan _a_, _a_, there are two upright posts, upon which,
and in holes of the back wall, two horizontal beams _b_, _b_, are
supported. The pillars _c_, _c_, are sustained upon the bearers _d_,
_d_. At _e_, _e_, a deep quadrangular groove is made in the beams, for
fixing down the four boards which form the bottom of the steam-way. In
this groove any condensed water from the steam collects, and is carried
off by a pipe _f_, to prevent it falling back into the pan. Upon the
three sides of the pan not in contact with the wall, there are three
rows of boards hinged upon planks _b_, _b_. Behind the upper one, a
board is hung on at _g_, upon which the boiled salt is laid to drain.
The two other rows of boards are hooked on so as to cover the pan, as
shown at _h_. Whenever the salt is sufficiently drained, the upper
shelves are placed in a horizontal position; the salt is put into small
baskets, and carried into the stove-room. _i_, _k_, is the steam-trunk;
_l_, _m_, is a tunnel for carrying off the steam from the middle of the
pan, when this is uncovered by lifting the boards.

In proportion as the brine becomes concentrated by evaporation, more is
added from the settling reservoir of the graduation-house, till finally
small crystals appear on the surface. No more weak brine is now added,
but the charge is worked off, care being taken to remove the scum, as it
appears. In some places the first pan is called a schlot-pan, in which
the concentration is carried only so far as to cause the deposition of
the sludge, from which the saline solution is run into another pan, and
gently evaporated, to produce the precipitation of the fine salt. This
salt should be continually raked towards the cooler and more elevated
sides of the pan, and then lifted out with cullender-shovels into large
conical baskets, arranged in wooden frames round the border of the pan,
so that the drainage may flow back into the boiling liquor. The drained
salt is transferred to the hurdles or baskets in the stove-room, which
ought to be kept at a temperature of from 120° to 130°, Fahr. The salt
is then stowed away in the warehouse.

The graduation range should be divided lengthwise into several sections:
the first to receive the water of the spring, the lake, or the sea; the
second, the water from the first shower-receiver; the third, the water
from the second receiver; and so on. The pumps are usually placed in the
middle of the building, and lift the brine from the several receivers
below into the alternate elevated cisterns. The square wooden spouts of
distribution may be conveniently furnished with a slide-board, attached
to each of their sides, to serve as a general valve for opening or
shutting many trickling orifices at once. The rate of evaporation at
Moutiers is exhibited by the following table:----

  +-----------------------+----------------+----------------+-------+
  |   Number of Showers.  |Total Surface of|Specific Gravity| Water |
  |                       |  the  Fagots.  |  of the Brine. |evapo- |
  |                       |                |                |rated. |
  +-----------------------+----------------+----------------+-------+
  |                       |                |     1·010      | 0·000 |
  |1 and 2                |5158 square feet|     1·023      | 0·540 |
  |3, 4, 5, 6, 7, 8, and 9|2720            |     1·072      | 0·333 |
  |10                     | 550            |     1·140      | 0·062 |
  |                                                           ----- |
  |                                        Total evaporation  0·935 |
  |     Water remaining in the brine at the density of 1·140  1·065 |
  |                                                           ----- |
  |                   Water assigned at the density of 1·010  1·000 |
  +-----------------------------------------------------------------+

From the above table it appears that no less than 10 falls of the brine
have been required to bring the water from the specific gravity 1·010 to
1·140, or 18° Baumé. The evaporation is found to proceed at nearly the
same rate with the weaker water, and with the stronger, within the above
limits. When it arrives at a density of from 1·140 to 1·16, it is run
off into the settling cisterns. M. Berthier calculates, that upon an
average, in ordinary weather, at Moutiers, 60 kilogrammes of water (13
gallons, imp.) are evaporated from the fagots, in the course of 24
hours, for every square foot of their surface. Without the aid of
currents of air artificially warmed, such an amount of evaporation could
not be reckoned upon in this country. In the _schlotting_, or throwing
down of the sediment, a little bullock’s blood, previously beaten up
with some cold brine, promotes the clarification. When the brine
acquires, by brisk ebullition, the density of 1·200, it should be run
off from the preparation, to the finishing or salting pans.

The mother-water contains a great deal of chloride of magnesium, along
with chloride of sodium, and sulphate of magnesia. Since the last two
salts mutually decompose each other at a low temperature, and are
transformed into sulphate of soda, which crystallizes, and muriate of
magnesia, which remains dissolved, the mother-water with this view may
be exposed in tanks to the frost during winter, when it affords three
successive crystalline deposits, the last being sulphate of soda, nearly
pure.

The chloride of magnesium, or bittern, not only deteriorates the salt
very much, but occasions a considerable loss of weight. It may, however,
be most advantageously got rid of, and converted into chloride of sodium
by the following simple expedient:----Let quicklime be introduced in
equivalent quantity to the magnesia present, and it will precipitate
this earth, and form chloride of calcium, which will immediately react
upon the sulphate of soda in the mother-water, with the production of
sulphate of lime and chloride of sodium. The former being sparingly
soluble, is easily separated. Lime, moreover, decomposes directly the
chloride of magnesium, but with the effect of merely substituting
chloride of calcium in its stead. But in general there is abundance of
sulphate of soda in brine springs to decompose the chloride of calcium.
A still better way of proceeding with sea-water, would be to add to it,
in the settling tank, the quantity of lime equivalent to the magnesia,
whereby an available deposit of this earth would be obtained, at the
same time that the brine would be sweetened. Water thus purified may be
safely crystallized by rapid evaporation.

In summer, the saturated boiling brine is crystallized by passing it
over vertical ropes; for which purpose 100,000 metres (110,000 yards)
are mounted in an apartment 70 metres (77 yards) long. When the salt has
formed a crust upon the ropes about 2-1/2 inches thick, it is broken
off, allowed to fall upon the clean floor of the apartment, and then
gathered up. The salting of a charge, which would take 5 or 6 days in
the pan, is completed in this way in 17 hours; but the mother-waters are
more abundant. The salt is, however, remarkably pure.

The boilers constructed at Rosenheim, in Bavaria, evaporate 3-1/2 pounds
of water for every pound of wood burned; which is reckoned a favourable
result; but some of those described under EVAPORATION, would throw off
much more.

“The rock salt mines and principal brine springs are in Cheshire; and
the chief part of the Cheshire salt, both fossil and manufactured, is
sent by the river Weaver to Liverpool, a very small proportion of it
being conveyed elsewhere, by canal or land carriage. There are brine
springs in Staffordshire, from which Hull is furnished with white salt;
and in Worcestershire, from which Gloucester is supplied. If to the
quantity shipped by the Weaver, 100,000 tons of white salt are added
annually for internal consumption and exports, exclusive of Liverpool,
the total manufacture will be approached very nearly; but as there is
now no check from the excise, it is impossible to ascertain it exactly.
Fossil salt is used in small quantities at some of the Cheshire
manufactories, to strengthen the brine, but is principally exported;
some to Ireland, but chiefly to Belgium and Holland.”[52] The average
quantity of rock salt sent annually down the river Weaver, from the
mines in Cheshire, between the years 1803 and 1834 inclusive, was 86,000
tons, of 2,600 lbs. each; the greatest being 125,658, in the year 1823,
and the least 47,230, in the year 1813. The average quantity of white
salt sent annually down the Weaver from the manufactories in Cheshire
during the same period, was 221,351; the greatest being 383,669, in the
year 1832, and the least being 120,486, in the year 1811.

  [52] Tables of the Revenue, Population, Commerce, &c., for 1836, p.
  122.

M. Clement-Desormes, engineer and chief _actionnaire_ of the great
salt-works of Dieuze, in France, informs me that the internal
consumption of that kingdom is rather more than 200,000 tons per annum,
being at the rate of 6-1/2 kilogrammes for each individual of a
population estimated at 32,000,000. As the retail price of salt in
France is 10 sous per kilogramme (of 2-1/5 lbs. avoird.), while in this
country it is not more than 2 sous (1 penny), its consumption per head
will be much greater with us; and, taking into account the immense
quantity of salted provisions that are used, it may be reckoned at 22
lbs.; whence our internal consumption will be 240,000 tons, instead of
100,000, as quoted above, from the tables published by the Board of
Trade.

In 1836, 9,622,427 bushels, of 56 lbs. = 240,560 tons of salt, value
173,923_l._, were exported from the United Kingdom, of which 1,350,849
bushels went to Russia; 1,235,086 to Belgium; 314,132 to the Western
coast of Africa; 1,293,560 to the British North American colonies;
2,870,808 to the United States of America; 53,299 to New South Wales,
Van Diemen’s Land, and other Australian settlements; 58,735 to the
British West Indies; and 90,655 to Guernsey, Jersey, Alderney, and Man.


SAND (Eng. and Germ.; _Sable_, Fr.); is the name given to any mineral
substance in a hard granular or pulverulent form, whether strewed upon
the surface of the ground, found in strata at a certain depth, forming
the beds of rivers, or the shores of the sea. The siliceous sands seem
to be either original crystalline formations, like the sand of Neuilly,
in 6-sided prisms, terminated by two 6-sided pyramids, or the _débris_
of granitic, schistose, quartzose, or other primitive crystalline rocks,
and are abundantly distributed over the globe; as in the immense plains
known under the names of downs, deserts, _steppes_, _landes_, &c.,
which, in Africa, Asia, Europe, and America, are entirely covered with
loose sterile sand. Valuable metallic ores, those of gold, platinum,
tin, copper, iron, titanium, often occur in the form of sand, or mixed
with that earthy substance. Pure siliceous sands are very valuable for
the manufacture of glass, for making mortars, filters, ameliorating
dense clay soils, and many other purposes. For moulder’s sand, see
FOUNDING. Lynn and Ryegate furnish our purest siliceous sand.


SANDAL or RED SAUNDERS WOOD (_Santal_ Fr.; _Sandelholz_ Germ.); is the
wood of the _Pterocarpus santalinus_, a tree which grows in Ceylon, and
on the coast of Coromandel. The old wood is preferred by dyers. Its
colouring matter is of a resinous nature; and is, therefore, quite
soluble in alcohol, essential oils, and alkaline lyes; but sparingly in
boiling water, and hardly if at all in cold water. The colouring matter
which is obtained by evaporating the alcoholic infusion to dryness, has
been called _santaline_; it is a red resin, which is fusible at 212° F.
It may also be obtained by digesting the rasped sandal wood in water of
ammonia, and afterwards saturating the ammonia with an acid. The
_santaline_ falls, and the supernatant liquor, which is yellow by
transmitted, appears blue by reflected light. Its spirituous solution
affords a fine purple precipitate with the protochloride of tin, and a
violet one with the salts of lead. Santaline is very soluble in acetic
acid, and the solution forms permanent stains upon the skin.

Sandal wood is used in India, along with one-tenth of _sapan_ wood (the
_Cæsalpinia sapan_ of Japan, Java, Siam, Celebes, and the Philippine
isles), principally for dyeing silk and cotton. Trommsdorf dyed wool,
cotton, and linen a carmine hue by dipping them alternately in alkaline
solution of the sandal wood, and in an acidulous bath. Bancroft obtained
a fast and brilliant reddish-yellow, by preparing wool with an alum and
tartar bath, and then passing it through a boiling bath of sandal wood
and sumac. Pelletier did not succeed in repeating this experiment.
According to Togler, wool, silk, cotton, and linen, mordanted with salt
of tin, and dipped in a cold alcoholic tincture of the wood, or the same
tincture mixed with 8 parts of boiling water, become of a superb
ponceau-red colour. With alum, they took a scarlet-red; with sulphate of
iron, a deep violet, or brown-red. Unluckily these dyes do not stand
exposure to light well.


SANDARACH, is a peculiar resinous substance, the product of the _Thuya
articulata_, a small tree of the coniferous family, which grows in the
northern parts of Africa, especially round Mount Atlas.

The resin comes to us in pale yellow, transparent, brittle, small tears,
of a spherical or cylindrical shape. It has a faint aromatic smell, does
not soften, but breaks between the teeth, fuses readily with heat, and
has a specific gravity of from 1·05 to 1·09. It contains three different
resins; one soluble in spirit of wine, somewhat resembling _pinic acid_
(see TURPENTINE); one not soluble in that menstruum; and a third,
soluble only in alcohol of 90 per cent. It is used as pounce-powder for
strewing over paper erasures, as incense, and in varnishes.


SAPAN WOOD, is a species of the _Cæsalpinia_ genus, to which Brasil wood
belongs. It is so called by the French, because it comes to them from
Japan, which they corruptly pronounce Sapan. As all the species of this
tree are natives of either the East Indies or the New World, one would
imagine that they could not have been used as dye-stuffs in Europe
before the beginning of the 16th century. Yet the author of the article
“Brasil,” in Rees’ Cyclopædia, and Mr. Southey, in his History of
Brasil, say that _Brasil_ wood is mentioned nearly one hundred years
before the discoveries of Columbus and Vasco de Gama, by Chaucer, who
died in 1400; that it was known many ages before his time; and that it
gave the name to the country, instead of the country giving the name to
the wood, as I have stated, with Berthollet and other writers on dyeing.
The _Cæsalpinia sappan_, being a native of the Coromandel coast, may
_possibly_ have been transported along with other Malabar merchandise to
the Mediterranean marts in the middle ages; but the importation of so
lumbering an article in any considerable quantity by that channel, is so
improbable, that I am disposed to believe that Brasil wood was not
commonly used by the dyers of Europe before the discovery of the New
World.


SARD; see LAPIDARY.


SATIN (Eng., Fr., and Germ.); is the name of a silk stuff, first
imported from China, which is distinguished by its very smooth,
polished, and glossy surface. It is woven upon a loom with at least
five-leaved healds or heddles, and as many corresponding treddles. These
are so mounted as to rise and fall four at a time, raising and
depressing alternately four yarns of the warp, across the whole of which
the weft is thrown by the shuttle, so as to produce a uniform smooth
texture, instead of the chequered work resulting from intermediate
decussations, as in common webs. See TEXTILE FABRICS. Satins are woven
with the glossy or right side undermost, because the four-fifths of the
warp, which are always left there during the action of the healds, serve
to support the shuttle in its race. Were they woven in the reverse way,
the scanty fifth part of the warp threads could either not support, or
would be too much worn by the shuttle.


SATURATION, is the term at which any body has taken its full dose or
chemical proportion of any other with which it can combine; as water
with a salt, or an acid with an alkali in the neutro-saline state.


SCALIOLA, is merely ornamental plaster-work, produced by applying a pap
made of finely-ground calcined gypsum, mixed with a weak solution of
Flanders’ glue, upon any figure formed of laths nailed together, or
occasionally upon brickwork, and bestudding its surface, while soft,
with splinters (_scagliole_) of spar, marble, granite, bits of concrete,
coloured gypsum, or veins of clay, in a semi-fluid state. The substances
employed to colour the spots and patches, are the several ochres, boles,
_terra di Sienna_, chrome yellow, &c. The surface of the column is
turned smooth upon a lathe, polished with stones of different fineness,
and finished with some plaster-pap, to give it lustre. Pillars and other
flat surfaces are smoothed by a carpenter’s plane, with the chisel
finely serrated, and afterwards polished with plaster by friction. The
glue is the cause of the gloss, but makes the surface apt to be injured
by moisture, or even damp air.


SCARLET DYE. (_Teinture en écarlate_, Fr.; _Scharlachfärberei_, Germ.)
Scarlet is usually given at two successive operations. The boiler (see
_figs._ 364, 365., article DYEING,) is made of block tin, but its bottom
is formed occasionally of copper.

1. _The bouillon, or the colouring-bath._--For 100 pounds of cloth, put
into the water, when it is little more than lukewarm, 6 pounds of argal,
and stir it well. When the water becomes too hot for the hand, throw
into it, with agitation, one pound of cochineal in fine powder. An
instant afterwards, pour in 5 pounds of the clear mordant G, (see TIN
MORDANTS,) stir the whole thoroughly as soon as the bath begins to boil,
introduce the cloth, and wince it briskly for two or three rotations,
and then more slowly. At the end of a two-hours’ boil, the cloth is to
be taken out, allowed to become perfectly cool, and well washed at the
river, or winced in a current of pure water. (See an automatic plan of
washing described under the article RINSING MACHINE.)

2. _The rougie, or finishing dye._--The bouillon bath is emptied, and
replaced with water for the _rougie_. When it is on the point of
boiling, 5-1/2 pounds of cochineal in fine powder are to be thrown in,
and mixed with care; when the crust, which forms upon the surface, opens
of itself in several places, 14 pounds of solution of tin (as above) are
to be added. Should the liquor be likely to boil over the edges of the
kettle, it must be refreshed with a little cold water. When the bath has
become uniform, the cloth is to be put in, taking care to wince it
briskly for two or three turns; then to boil it bodily for an hour,
thrusting it under the liquor with a rod whenever it rises to the
surface. It is lastly taken out, aired, washed at the river, and dried.

As no person has done more for the improvement of the scarlet dyes than
Poërner, I shall here give his processes in detail.

_Bouillon, or colouring._--For every pound of cloth or wool, take 14
drams of cream of tartar. When the bath is boiling, and the tartar all
dissolved, pour in successively 14 drams of solution of tin, (_Mordant_
F, TIN,) and let the whole boil together during a few minutes. Now
introduce the cloth, and boil it for 2 hours; then take it out, and let
it drain and cool.

_Rougie, or dye._--For every pound of woollen stuff, take 2 drams of
cream of tartar. When the bath begins to boil, add 1 ounce of cochineal
reduced to fine powder, stir the mixture well with a rod of willow or
any white wood, and let it boil for a few minutes. Then pour in, by
successive portions, 1 ounce of solution of tin (_Mordant_ F), stirring
continually with the rod. Lastly, dye as quickly as possible. The colour
will be a beautiful scarlet.

_Second scarlet process of Poërner_, the _bouillon_ being the same as
above given, and always estimated for 1 pound of cloth or wool.
_Rougie._--Take one ounce of cochineal in fine powder, and two ounces of
solution of tin without tartar.

_Third scarlet process of Poërner_; the _bouillon_ being as above.
_Rougie_ for a pound of cloth.--Take two drams of cream of tartar, one
ounce of cochineal, one ounce of solution of tin, and two ounces of sea
salt: dye as in process 1. The salt helps the dye to penetrate into the
cloth.

TABLES of the COMPOSITION of the BOUILLON and ROUGIE, by different
Authors, for 100 pounds of Cloth or Wool.

_Composition of the Bouillon._

  +------------+----------+----------+----------+----------+---------+
  |Names of the|  Starch. | Cream of |Cochineal.|Solution  | Common  |
  | Authors.   |          |  Tartar. |          | of Tin.  | Salt.   |
  +------------+----------+----------+----------+----------+---------+
  |            |_lb.  oz._|_lb.  oz._|_lb.  dr._|_lb.  oz._|_lb. oz._|
  |            |          |          |          |          |         |
  |Berthollet  | 0    0   |  6    0  |  8    0  |  5     0 |  0    0 |
  |Hellot      | 0    0   | 12    8  | 18    6  | 12     8 |  0    0 |
  |Scheffer    | 9    6   |  9    6  | 12    4  |  9     6 |  0    0 |
  |Poërner     | 0    0   | 10   15  |  0    0  | 10    15 |  0    0 |
  +------------+----------+----------+----------+----------+---------+

_Composition of the Rougie_.

  +------------+----------+----------+-----------+---------+---------+
  |Names of the|  Starch. | Cream of |Cochineal. |Solution | Common  |
  |  Authors.  |          | Tartar.  |           | of Tin. |  Salt.  |
  +------------+----------+----------+-----------+---------+---------+
  |            |_lb.  oz._|_lb.  oz._|_lb. oz._  |_lb. oz._|_lb. oz._|
  |Berthollet  | 0    0   |  0    0  |  5   8    | 14    0 |  0    0 |
  |Hellot      | 3    2   |  0    0  |  7   4    | 12    8 |  0    0 |
  |Scheffer    | 3    2   |  3    2  |  5   7-1/2|  4   11 |  0    0 |
  |           {| 0    0   |  1    8  |  6   4    |  6    4 |  0    0 |
  |Poërner    {| 0    0   |  0    0  |  6   4    | 12    8 |  0    0 |
  |           {| 0    0   |  1    8  |  6   4    |  6    4 | 12    8 |
  +------------+----------+----------+-----------+---------+---------+

M. Lenormand states that he has made experiments of verification upon
all the formulæ of the preceding tables, and declares his conviction
that the finest tint may be obtained by taking the _bouillon_ of
Scheffer, and the _rougie_ No. 4. of Poërner. The solution which
produced the most brilliant red, is that made according to the process
of mordant B (TIN). M. Robiquet has given the following prescription for
making a _printing scarlet_, for well-whitened woollen cloth.

Boil a pound of pulverized cochineal in four pints of water down to two
pints, and pass the decoction through a sieve. Repeat the boiling three
times upon the residuum, mix the eight pints of decoction, thicken them
properly with two pounds of starch, and boil into a paste. Let it cool
down to 104° F., then add four ounces of the subjoined solution of tin,
and two ounces of ordinary salt of tin (muriate). When a ponçeau red is
wanted, two ounces of pounded curcuma (turmeric) should be added.

The solution of tin above prescribed, is made by taking--one ounce of
nitric acid, of specific gravity 36° B. = 1·33; one ounce of sal
ammoniac; four ounces of grain tin. The tin is to be divided into eight
portions, and one of them is to be put into the acid mixture every
quarter of an hour.

A solution of chlorate of potassa (chloride?) is said to beautify
scarlet cloth in a remarkable manner.

Bancroft proposed to supplant the nitro-muriatic acid, by a mixture of
sulphuric and muriatic acids, for dissolving tin; but I do not find that
he succeeded in persuading scarlet-dyers to adopt his plans. In fact the
proper base is, in my opinion, a mixture of the protoxide and peroxide
of tin; and this cannot be obtained by acting upon the metal with the
murio-sulphuric acid. He also prescribed the extensive use of the
quercitron yellow to change the natural crimson of the cochineal into
scarlet, thereby economizing the quantity of this expensive dye-stuff.
See LAC DYE.


SCHEELE’S GREEN, is a pulverulent arsenite of copper, which may be
prepared as follows:--Form, first, an arsenite of potassa, by adding
gradually 11 ounces of arsenious acid to 2 pounds of carbonate of
potassa, dissolved in 10 pounds of boiling water; next, dissolve 2
pounds of crystallized sulphate of copper in 30 pounds of water; filter
each solution, then pour the first progressively into the second, as
long as it produces a rich grass-green precipitate. This being thrown
upon a filter-cloth, and edulcorated with warm water, will afford 1
pound 6 ounces of this beautiful pigment. It consists of, oxide of
copper 28·51, and of arsenious acid 71·46. This green is applied by an
analogous double decomposition to cloth. See CALICO-PRINTING.


SCHWEINFURTH GREEN, is a more beautiful and velvety pigment than the
preceding, which was discovered in 1814, by MM. Rusz and Sattler, at
Schweinfurth, and remained for many years a profitable secret in their
hands. M. Liebig having made its composition known, in 1822, it has been
since prepared in a great many colour-works. Braconnot published, about
the same time, another process for manufacturing the same pigment. Its
preparation is very simple; but its formation is accompanied with some
interesting circumstances. On mixing equal parts of acetate of copper
and arsenious acid, each in a boiling concentrated solution, a bulky
olive-green precipitate is immediately produced; while much acetic acid
is set free. The powder thus obtained, appears to be a compound of
arsenious acid and oxide of copper, in a peculiar state; since when
decomposed by sulphuric acid, no acetic odour is exhaled. Its colour is
not changed by drying, by exposure to air, or by being heated in water.
But, if it be boiled in the acidulous liquor from which it was
precipitated, it soon changes its colour, as well as its state of
aggregation, and forms a new deposit in the form of a dense granular
beautiful green powder. As fine a colour is produced by ebullition
during five or six minutes, as is obtained at the end of several hours
by mixing the two boiling solutions, and allowing the whole to cool
together. In the latter case, the precipitate, which is slight and
flocky at first, becomes denser by degrees; it next betrays green spots,
which progressively increase, till the mass grows altogether of a
crystalline constitution, and of a still more beautiful tint than if
formed by ebullition.

When cold water is added to the mixed solutions, immediately after the
precipitate takes place, the development of the colour is retarded,
with the effect of making it much finer. The best mode of procedure, is
to add to the blended solutions, their own bulk of cold water, and to
fill a globe up to the neck with the mixture in order to prevent the
formation of any such pellicle on the surface, as might, by falling to
the bottom, excite premature crystallization. Thus the reaction
continues during two or three days with the happiest effect. The
difference of tint produced by these variations, arises merely from the
different sizes of the crystalline particles; for when the several
powders are levigated upon a porphyry slab to the same degree, they have
the same shade. Schweinfurth green, according to M. Ehrmann’s
researches, in the 31st _Bulletin de la Société Industrielle de
Mulhausen_, consists of, oxide of copper 31·666, arsenious acid 58·699,
acetic acid 10·294. Kastner has given the following prescription for
making this pigment:--For 8 parts of arsenious acid, take from 9 to 10
of verdigris; diffuse the latter through water at 120° F., and pass the
pap through a sieve; then mix it with the arsenical solution, and set
the mixture aside, till the reaction of the ingredients shall produce
the wished-for shade of colour. If a yellowish tint be desired, more
arsenic must be used. By digesting Scheele’s green in acetic acid, a
variety of Schweinfurth green may be obtained.

Both of the above colours are rank poisons. The first was detected a few
years ago, as the colouring-matter of some Parisian _bonbons_, by the
_conseil de salubrité_; since which the confectioners were prohibited
from using it, by the French government.


SCOURING, _or renovating articles of dress_. This art has been much more
studied by Frenchmen, who wear the same coats for two or three years,
than by Englishmen, who generally cast them off after so many months.
The workmen who remove greasy stains from dress, are called, in France,
_teinturiers-degraisseurs_, because they are often obliged to combine
dyeing with scouring operations. The art of cleansing clothes being
founded upon the knowledge of solvents, the practitioner of it should,
as we shall presently illustrate by examples, be acquainted with the
laws of chemical affinity.

Among the spots which alter the colours fixed upon stuffs, some are
caused by a substance which may be described as _simple_, in common
language; and others by a substance which results from the combination
of two or more bodies, that may act separately or together upon the
stuff, and which may therefore be called _compound_.

_Simple stains._--Oils and fats are the substances which form the
greater part of simple stains. They give a deep shade to the ground of
the cloth; they continue to spread for several days; they attract the
dust, and retain it so strongly, that it is not removable by the brush;
and they eventually render the stain lighter coloured upon a dark
ground, and of a disagreeable gray tint upon a pale or light ground.

The general principle of cleansing all spots, consists in applying to
them a substance which shall have a stronger affinity for the matter
composing them, than this has for the cloth, and which shall render them
soluble in some liquid menstruum, such as water, spirits, naphtha, oil
of turpentine, &c. See BLEACHING.

Alkalis would seem to be proper in this point of view, as they are the
most powerful solvents of grease; but they act too strongly upon silk
and wool, as well as change too powerfully the colours of dyed stuffs,
to be safely applicable in removing stains. The best substances for this
purpose are--1. Soap. 2. Chalk, fuller’s earth, soap-stone or steatite
(called in this country French chalk). These should be merely diffused
through a little water into a thin paste, spread upon the stain, and
allowed to dry. The spot requires now to be merely brushed. 3. Ox-gall
and yolk of egg have the property of dissolving fatty bodies without
affecting perceptibly the texture or colours of cloth, and may therefore
be employed with advantage. The ox-gall should be purified, to prevent
its greenish tint from degrading the brilliancy of dyed stuffs, or the
purity of whites. Thus prepared (see GALL), it is the most precious of
all substances known for removing these kinds of stains. 4. The volatile
oil of turpentine will take out only recent stains; for which purpose it
ought to be previously purified by distillation over quicklime. Wax,
rosin, turpentine, pitch, and all resinous bodies in general, form
stains of greater or less adhesion, which may be dissolved out by pure
alcohol. The juices of fruits, and the coloured juices of all vegetables
in general, deposit upon clothes marks in their peculiar hues. Stains of
wine, mulberries, black currants, morellos, liquors, and weld, yield
only to soaping with the hand, followed by fumigation with sulphurous
acid; but the latter process is inadmissible with certain coloured
stuffs. Iron mould or rust stains may be taken out almost
instantaneously with a strong solution of oxalic acid. If the stain is
recent, cream of tartar will remove it.

_Compound spots._--That mixture of rust of iron and grease called
_cambouis_ by the French, is an example of this kind, and requires two
distinct operations; first, the removal of the grease, and then of the
rust, by the means above indicated.

Mud, especially that of cities, is a compound of vegetable remains, and
of ferruginous matter in a state of black oxide. Washing with pure
water, followed if necessary with soaping, will take away the vegetable
juices; and then the iron may be removed with cream of tartar, which
itself must, however, be well washed out. Ink stains, when recent, may
be taken out by washing, first with pure water, next with soapy water,
and lastly with lemon juice; but if old, they must be treated with
oxalic acid. Stains occasioned by smoke, or by sauces browned in a
frying-pan, may be supposed to consist of a mixture of pitch, black
oxide of iron, empyreumatic oil, and some saline matters dissolved in
pyrolignous acid. In this case several reagents must be employed to
remove the stains. Water and soap dissolve perfectly well the vegetable
matters, the salts, the pyrolignous acid, and even the empyreumatic oils
in a great measure; the essence of turpentine will remove the rest of
the oils and all the pitchy matter; then oxalic acid may be used to
discharge the iron. Coffee stains require a washing with water, with a
careful soaping, at the temperature of 120° F., followed by
sulphuration. The two latter processes may be repeated twice or thrice.
Chocolate stains may be removed by the same means, and more easily.

As to those stains which change the colour of the stuff, they must be
corrected by appropriate chemical reagents or dyes. When black or brown
cloth is reddened by an acid, the stain is best counteracted by the
application of water of ammonia. If delicate silk colours are injured by
soapy or alkaline matters, the stains must be treated with colourless
vinegar of moderate force. An earthy compound for removing grease spots
is made as follows:--Take fuller’s earth, free it from all gritty matter
by elutriation with water; mix with half a pound of the earth so
prepared, half a pound of soda, as much soap, and eight yolks of eggs
well beat up with half a pound of purified ox-gall. The whole must be
carefully triturated upon a porphyry slab; the soda with the soap in the
same manner as colours are ground, mixing in gradually the eggs and the
ox-gall previously beat together. Incorporate next the soft earth by
slow degrees, till a uniform thick paste be formed, which should be made
into balls or cakes of a convenient size, and laid out to dry. A little
of this detergent being scraped off with a knife, made into a paste with
water, and applied to the stain, will remove it. Purified ox-gall is to
be diffused through its own bulk of water, applied to the spots, rubbed
well into them with the hands till they disappear, after which the stuff
is to be washed with soft water. It is the best substance for removing
stains on woollen clothes.

The redistilled oil of turpentine may also be rubbed upon the dry
clothes with a sponge or a tuft of cotton, till the spot disappear; but
it must be immediately afterwards covered with some plastic clay reduced
to powder. Without this precaution, a cloud would be formed round the
stain, as large as the part moistened with the turpentine.

Oxalic acid may be applied in powder upon the spot previously moistened
with water, well rubbed on, and then washed off with pure water.

Sulphurous acid is best generated at the moment of using it. If the
clothes be much stained, they should be suspended in an ordinary
fumigating chamber. For trifling stains, the sulphur may be burned under
the wide end of a small card or paper funnel, whose upper orifice is
applied near the cloth.

_Manipulations of the scourer._--These consist, first, in washing the
clothes in clear soft water, or in soap-water. The cloth must be next
stretched on a sloping board, and rubbed with the appropriate reagent as
above described, either by a sponge or a small hard brush. The
application of a redhot iron a little way above a moistened spot often
volatilizes the greasy matter out of it. Stains of pitch, varnish, or
oil paint, which have become dry, must first be softened with a little
fresh butter or lard, and then treated with the powder of the scouring
ball. When the gloss has been taken from silk, it may be restored by
applying the filtered mucilage of gum tragacanth; stretching it upon a
frame to dry. Ribbons are glossed with isinglass. Lemon juice is used to
brighten scarlet spots, after they have been cleaned.


SEAL ENGRAVING. The art of _engraving gems_ is one of extreme nicety.
The stone having received its desired form from the lapidary, the
engraver fixes it by cement to the end of a wooden handle, and then
draws the outline of his subject, with a brass needle or a diamond, upon
its smooth surface.

[Illustration: 969 970 971 972]

_Fig._ 969. represents the whole of the seal engraver’s lathe. It
consists of a table on which is fixed the mill, a small horizontal
cylinder of steel, into one of whose extremities the tool is inserted,
and which is made to revolve by the usual fly-wheel, driven by a
treddle. The tools that may be fitted to the mill-cylinder, are the
following: _fig._ 970. a hollow cylinder, for describing circles, and
for boring; _fig._ 971. a knobbed tool, or rod terminated by a small
ball; _fig._ 972. a stem terminated with a cutting disc, whose edge may
be either rounded, square, or sharp; being in the last case called a
saw.

Having fixed the tool best adapted to his style of work in the mill, the
artist applies to its cutting point, or edge, some diamond-powder, mixed
up with olive oil; and turning the wheel, he holds the stone against the
tool, so as to produce the wished-for delineation and erosion. A similar
apparatus is used for engraving on glass.

In order to give the highest degree of polish to the engraving, tools of
boxwood, pewter, or copper, bedaubed with moistened tripoli or
rotten-stone, and lastly, a brush, are fastened to the mill. These are
worked like the above steel instruments. Modern engravings on precious
stones, have not in general the same fine polish as the antient. The
article GEMS, in Rees’ Cyclopædia, contains a variety of valuable
information on this subject, equally interesting to the artist and the
scholar.


SEALING-WAX. (_Cire à cacheter_, Fr.; _Siegellack_, Germ.) The Hindus
from time immemorial have possessed the resin lac, and were long
accustomed to use it for sealing manuscripts before it was known in
Europe. It was first imported from the East into Venice, and then into
Spain; in which country sealing-wax became the object of a considerable
commerce, under the name of Spanish wax.

If shellac be compounded into sealing-wax, immediately after it has been
separated by fusion from the palest qualities of stick or seed lac, it
then forms a better and less brittle article, than when the shellac is
fused a second time. Hence sealing-wax, rightly prepared in the East
Indies, deserves a preference over what can be made in other countries,
where the lac is not indigenous. Shellac can be restored in some degree,
however, to a plastic and tenacious state by melting it with a very
small portion of turpentine. The palest shellac is to be selected for
bright-coloured sealing-wax, the dark kind being reserved for black.

The following prescription may be followed for making red
sealing-wax:--Take 4 ounces of shellac, 1 ounce of Venice turpentine
(some say 1-1/2 ounces), and 3 ounces of vermillion. Melt the lac in a
copper pan suspended over a clear charcoal fire, then pour the
turpentine slowly into it, and soon afterwards add the vermillion,
stirring briskly all the time of the mixture with a rod in either hand.
In forming the round sticks of sealing-wax, a certain portion of the
mass should be weighed while it is ductile, divided into the desired
number of pieces, and then rolled out upon a warm marble slab, by means
of a smooth wooden block, like that used by apothecaries for rolling a
mass of pills. The oval sticks of sealing-wax are cast in moulds, with
the above compound in a state of fusion. The marks of the lines of
junction of the mould-box may be afterwards removed by holding the
sticks over a clear fire, or passing them over a blue gas-flame. Marbled
sealing-wax is made by mixing two, three, or more coloured kinds of it,
while they are in a semi-fluid state. From the viscidity of the several
masses, their incorporation is left incomplete, so as to produce the
appearance of marbling. Gold sealing-wax is made simply by stirring
gold-coloured mica spangles into the melted resins. Wax may be scented
by introducing a little essential oil, essence of musk, or other
perfume. If 1 part of balsam of Peru be melted along with 99 parts of
the sealing-wax composition, an agreeable fragrance will be exhaled in
the act of sealing with it. Either lamp black or ivory black serves for
the colouring-matter of black wax. Sealing-wax is often adulterated with
rosin; in which case it runs into thin drops at the flame of a candle.


SEA WATER, is composed as follows, according to the author of the
article _Salines_, in the _Dictionnaire Technologique_:--Chloride of
sodium, 2·50; chloride of magnesium, 0·35; sulphate of magnesia, 0·58;
carbonates of lime and magnesia, 0·02; sulphate of lime, 0·01; water,
96·54, in 100 parts. See SALT, SEA.


SEGGAR, or SAGGER, is the cylindric case, of fire-clay, in which fine
stoneware is enclosed while being baked in the kiln.


SELENIUM, from Σεληνη, the moon, is a metalloid principle, discovered by
Berzelius, in 1817. It occurs sparingly in combination with several
metals, as lead, cobalt, copper, and quicksilver, in the Harz, at
Tilkerode; with copper and silver (_Eukairite_) in Sweden, with
tellurium and bismuth in Norway, with tellurium and gold in
Siebenbürgen, in several copper and iron pyrites, and with sulphur in
the volcanic products of the Lipari Islands. Selenium has been found
likewise in a red sediment which forms upon the bottoms of the lead
chambers in which oil of vitriol has been made from peculiar pyrites, or
pyritous sulphur. The extraction of selenium from that deposit, is a
very complex process.

Selenium, after being fused and slowly cooled, appears of a bluish-gray
colour, with a glistening surface; but it is reddish brown, and of
metallic lustre when quickly cooled, It is brittle, not very hard, and
has little tendency to assume the crystalline state. Selenium is
dark-red in powder, and transparent, with a ruby cast, in thin scales.
Its specific gravity is 4·30. It softens at the temperature of 176° F.,
is of a pasty consistence at 212°, becomes liquid at a somewhat higher
heat, forming in close vessels dark-yellow vapours, which condense into
black drops; but in the air, the fumes have a cinnabar-red colour.

This singular substance, apparently intermediate in its constitution
between sulphur and metals, has not hitherto been applied to any use in
the arts.


SELTZER WATER. See SODA-WATER, and WATERS, MINERAL.


SEPIA, is a pigment prepared from a black juice secreted by certain
glands of the cuttle-fish, which the animal ejects to darken the water
when it is pursued. One part of it is capable of making 1000 parts of
water nearly opaque. All the varieties of this mollusca secrete the same
juice; but the _Sepia officinalis_, the _Sepia ioligo_, and the _Sepia
tunicata_, are chiefly sought after for making the pigment. The first,
which occurs abundantly in the Mediterranean, affords most colour; the
sac containing it being extracted, the juice is to be dried as quickly
as possible, because it runs rapidly into putrefaction. Though insoluble
in water, it is extremely diffusible through it, and is very slowly
deposited. Caustic alkalis dissolve the sepia, and turn it brown; but in
proportion as the alkali becomes carbonated by exposure to air, the
sepia falls to the bottom of the vessel. Chlorine blanches it slowly. It
consists of carbon in an extremely divided state, along with albumine,
gelatine, and phosphate of lime.

The dried native sepia is prepared for the painter, by first triturating
it with a little caustic lye, then adding more lye, boiling the liquid
for half an hour, filtering, next saturating the alkali with an acid,
separating the precipitate, washing it with water, and finally drying it
with a gentle heat. The pigment is of a brown colour, and a fine grain.


SEPTARIA, called antiently _ludus Helmontii_, (the _quoits_ of Van
Helmont, from their form,) are lenticular concretions of clay ironstone,
intersected by veins of calc-spar, which, when calcined, and ground to
powder, form an excellent hydraulic cement. See MORTAR, HYDRAULIC.


SERPENTINE, is a mineral of the magnesian family, of a green colour; it
is scratched by calcareous spar, is sectile, tough, and therefore easily
cut into ornamental forms. It occurs in Unst and Fetlar, in Shetland; at
Portsoy, in Banffshire; in Cornwall; and the Isle of Holyhead. The
floors of bakers’ ovens are advantageously laid with slabs of
serpentine.


SHAFT, in mining, signifies a perpendicular or slightly inclined pit.


SHAGREEN. (_Chagrin_, Fr. and Germ.) The true oriental shagreen is
essentially different from all modifications of leather and parchment.
It approaches the latter somewhat, indeed, in its nature, since it
consists of a dried skin, not combined with any tanning or foreign
matter whatever. Its distinguishing characteristic is having the grain
or hair side covered over with small rough round specks or granulations.

It is prepared from the skins of horses, wild asses, and camels; of
strips cut along the chine, from the neck towards the tail, apparently
because this stronger and thicker portion of the skin is best adapted to
the operations about to be described. These fillets are to be steeped in
water till the epidermis becomes loose, and the hairs easily come away
by the roots; after which they are to be stretched upon a board, and
dressed with the currier’s fleshing-knife. They must be kept continually
moist, and extended by cords attached to their edges, with the flesh
side uppermost upon the board. Each strip now resembles a wet bladder,
and is to be stretched in an open square wooden frame by means of
strings tied to its edges, till it be as smooth and tense as a
drum-head. For this purpose it must be moistened and extended from time
to time in the frame.

The grain or hair side of the moist strip of skin must next be sprinkled
over with a kind of seeds called _Allabuta_, which are to be forced into
its surface either by tramping with the feet, or with a simple press, a
piece of felt or other thick stuff being laid upon the seeds. These
seeds belong probably to the _Chenapodium album_. They are lenticular,
hard, of a shining black colour, farinaceous within, about the size of
poppy seed, and are sometimes used to represent the eyes in wax figures.

The skin is exposed to dry in the shade, with the seeds indented into
its surface; after which it is freed from them by shaking it, and
beating upon its other side with a stick. The outside will be then
horny, and pitted with small hollows corresponding to the shape and
number of the seeds.

In order to make the next process intelligible, we must advert to
another analogous and well-known operation. When we make impressions in
fine-grained dry wood with steel punches or letters of any kind, then
plane away the wood till we come to the level of the bottom of these
impressions, afterwards steep the wood in water, the condensed or
punched points will swell above the surface, and place the letters in
relief. Snuff-boxes have been sometimes marked with prominent figures in
this way. Now shagreen is treated in a similar manner.

The strip of skin is stretched in an inclined plane, with its upper edge
attached to hooks, and its under one loaded with weights, in which
position it is thinned off with a proper semi-lunar knife, but not so
much as to touch the bottom of the seed-pits or depressions. By
maceration in water, the skin is then made to swell, and the pits become
prominent over the surface which had been shaved. The swelling is
completed by steeping the strips in a warm solution of soda, after which
they are cleansed by the action of salt brine, and then dyed.

In the East the following processes are pursued. Entirely white shagreen
is obtained by imbuing the skin with a solution of alum, covering it
with the dough made with Turkey wheat, and after a time washing this
away with a solution of alum. The strips are now rubbed with grease or
suet, to diminish their rigidity, then worked carefully in hot water,
curried with a blunt knife, and afterwards dried. They are dyed red with
decoction of cochineal or kermes, and green with fine copper filings and
sal ammoniac, the solution of this salt being first applied, then the
filings being strewed upon the skin, which must be rolled up and loaded
with weights for some time; blue is given with indigo, quicklime, soda,
and honey; and black, with galls and copperas.


SHALE, or SLATE-CLAY, is an important stratiform member of the
coal-measures. See PITCOAL.


SHAMOY LEATHER. See LEATHER.


SHEATHING OF SHIPS. For this purpose many different metals and metallic
alloys have been lately proposed. From a train of researches which I
made for an eminent copper company, a few years ago, upon various
specimens of sheathing which had been exposed upon ships during many
voyages, it appeared that copper containing a minute but definite
proportion of tin, was by far the most durable.


SHELLAC. See LAC, and SEALING-WAX.


SIENITE, is a granular aggregated compound rock, consisting of felspar
and hornblende, sometimes mixed with a little quartz and mica. The
hornblende is the characteristic ingredient, and serves to distinguish
sienite from granite, with which it has been sometimes confounded;
though the felspar, which is generally red, is the more abundant
constituent. The Egyptian sienite, containing but little hornblende,
with a good deal of quartz and mica, approaches most nearly to granite.
It is equally metalliferous with porphyry; in the island of Cyprus, it
is rich in copper; and in Hungary, it contains many valuable gold and
silver mines.

Sienite forms a considerable part of the Criffle, a hill in Galloway. It
takes its name from the city of Syene, in the Thebaid, near the
cataracts of the Nile, where this rock abounds. It is an excellent
building-stone, and was imported in large quantities from Egypt by the
Romans, for the architectural and statuary decorations of their capital.


SILICA and SILICON. (_Silice_, _silicium_, Fr.; _Kieselerde_, _kiesel_,
Germ.) Silica was till lately ranked among the earths proper; but since
the researches of Davy and Berzelius, it has been transferred to the
chemical class of acids. It constitutes the principal portion of most of
the hard stones and minerals which compose the crust of the globe;
occurring nearly pure in rock crystal, quartz, agate, calcedony, flint,
&c. Silica or silicic acid may be obtained perfectly pure, and also in
the finest state of comminution, by taking the precipitate formed by
passing silicated fluoric gas through water, filtering, washing, and
igniting it, to expel the last traces of the fluoride of silicon. The
powder thus obtained is so light as to be blown away with the least
breath of air. Silica may be more conveniently procured, however, by
fusing ground flint with four times its weight of a mixture, in equal
parts, of dry carbonate of potassa and carbonate of soda, in a platinum
or silver crucible. The alkaline carbonates should be first fused, and
the flint powder sprinkled into the liquid, as long as it dissolves with
effervescence. The mass is to be then allowed to cool, dissolved in
dilute muriatic acid; the solution is to be filtered, and evaporated to
dryness; the dry crust is to be pulverized, digested for two hours with
a little muriatic acid, to remove any iron and alumina that may be
present, next washed with hot water, drained, dried, and ignited.

The above silicate of potassa and soda is the compound called soluble
glass, which applied in solution to the surface of wood, calico, paper,
&c., renders them unsusceptible of taking fire on the contact of an
ignited body.

Silica, as thus prepared, is a white powder, rough to the touch, gritty
between the teeth, absolutely insoluble in water, acids, and most
liquids. Its specific gravity is 2·66. It cannot be fused by the most
intense heat of our furnaces, but at the flame of the oxy-hydrogen
blowpipe it melts into a limpid colourless glass. By peculiar chemical
methods, an aqueous solution of it may be made artificially, similar to
what nature presents us with in many thermal springs, as in those of
Reikum and of Geyser in Iceland, and of most mineral waters, in minute
quantity. There is no acid except the fluoric which can directly
dissolve dry or calcined silica. Silica is composed of 48·04 silicon,
and 51·96 oxygen.


SILICATES, are compounds of silicic acid (silica), with the bases
alumina, lime, magnesia, potassa, soda, &c. They constitute the greater
number by far of the hard minerals which encrust the terrestrial globe.
Thus cyanite is a subsilicate of alumina; felspar and leucite, are
silicates of alumina and potassa; albite and analcime, are silicates of
alumina and soda; stilbite, prehnite, mesolite, labradorite, tourmaline,
mica, &c., are silicates of alumina and lime; chrysolite, steatite,
serpentine, and meerschaum, are silicates of magnesia; augite and
hornblende, are silicates of lime and magnesia, &c.


SILICON, called also silicium, may be obtained by burning potassium in
silicated fluoric gas. The product of the combustion is a brown cinder,
which, on being thrown into water, disengages hydrogen with violence,
and lets fall a dark liver-brown powder, upon which water exercises no
action. This matter is silicon mixed with a salt of difficult solution,
which is composed of fluorine, potassium, and silicon. This salt may,
however, be removed by a great deal of washing. The further details of
this curious subject will be given in my forthcoming system of
chemistry.


SILK MANUFACTURE. (_Fabrique de soie_, Fr.; _Seidenfabrik_, Germ.) This
may be divided into two branches: 1. the production of raw silk; 2. its
filature and preparation in the mill, for the purposes of the weaver and
other textile artisans. The threads, as spun by the silkworm, and wound
up in its cocoon, are all twins, in consequence of the twin orifice in
the nose of the insect through which they are projected. These two
threads are laid parallel to each other, and are glued more or less
evenly together by a kind of glossy varnish, which also envelopes them,
constituting nearly 25 per cent. of their weight. Each ultimate filament
measures about 1/2000 of an inch in average fine silk, and the pair
measures of course fully 1/1000 of an inch. In the raw silk, as imported
from Italy, France, China, &c., several of these twin filaments are
slightly twisted and agglutinated to form one thread, called a single.

The specific gravity of silk is 1·300, water being 1·000. It is by far
the most tenacious or the strongest of all textile fibres, a thread of
it of a certain diameter being nearly three times stronger than a thread
of flax, and twice stronger than hemp. Some varieties of silk are
perfectly white, but the general colour in the native state is a golden
yellow.

The production of silk was unknown in Europe till the sixth century,
when two monks, who brought some eggs of the silkworm from China or
India to Constantinople, were encouraged to breed the insect, and
cultivate its cocoons, by the Emperor Justinian. Several silk
manufactures were in consequence established in Athens, Thebes, and
Corinth, not only for rearing the worm upon mulberry-leaves, but for
unwinding its cocoons, for twisting their filaments into stronger
threads, and weaving these into robes. The Venetians having then and
long afterwards intimate commercial relations with the Greek empire,
supplied the whole of western Europe with silk goods, and derived great
riches from the trade.

About 1130, Roger II., king of Sicily, set up a silk manufacture at
Palermo, and another in Calabria, conducted by artisans whom he had
seized and carried off as prisoners of war in his expedition to the Holy
Land. From these countries, the silk industry soon spread throughout
Italy. It seems to have been introduced into Spain at a very early
period, by the Moors, particularly in Murcia, Cordova, and Granada. The
last town, indeed, possessed a flourishing silk trade when it was taken
by Ferdinand in the 15th century. The French having been supplied with
workmen from Milan, commenced, in 1521, the silk manufacture; but it was
not till 1564 that they began successfully to produce the silk itself,
when Traucat, a working gardener at Nismes, formed the first nursery of
white mulberry-trees, and with such success, that in a few years he was
enabled to propagate them over many of the southern provinces of France.
Prior to this time, some French noblemen, on their return from the
conquest of Naples, had introduced a few silkworms with the mulberry
into Dauphiny; but the business had not prospered in their hands. The
mulberry plantations were greatly encouraged by Henry IV.; and since
then they have been the source of most beneficial employment to the
French people. James I. was most solicitous to introduce the breeding of
silkworms into England, and in a speech from the throne he earnestly
recommended his subjects to plant mulberry-trees; but he totally failed
in the project. This country does not seem to be well adapted for this
species of husbandry, on account of the great prevalence of blighting
east winds during the months of April and May, when the worms require a
plentiful supply of mulberry-leaves. The manufacture of silk goods,
however, made great progress during that king’s peaceful and pompous
reign. In 1629 it had become so considerable in London, that the
silk-throwsters of the city and suburbs were formed into a public
corporation. So early as 1661 they employed 40,000 persons. The
revocation of the edict of Nantes, in 1685, contributed in a remarkable
manner to the increase of the English silk trade, by the influx of a
large colony of skilful French weavers, who settled in Spitalfields. The
great silk-throwing mill mounted at Derby, in 1719, also served to
promote the extension of this branch of manufacture; for soon
afterwards, in the year 1730, the English silk goods bore a higher price
in Italy than those made by the Italians, according to the testimony of
Keysler.

Till the year 1826, however, our silk manufactures in general laboured
under very grievous fiscal burdens. Foreign organzine, or twisted raw
silk, paid an import duty of 14_s._ 7-1/2_d._ per pound; raw Bengal
silk, 4_s._; and that from other places, 5_s._ 7-1/2_d._ Mr. Huskisson
introduced a bill at that time, reducing the duty on organzine to 5_s._,
and the duty on other raw silk to 3_d._ per pound. The total prohibition
of the import of French manufactured silks, which gave rise to so much
contraband trade, was also converted into a duty of 30 per cent. _ad
valorem_. During the reign of the prohibitory system, when our silk
weavers had no variety of patterns to imitate, and no adequate stimulus
to excel, on account of the monopoly which they possessed in the home
market, the inferiority of their productions was a subject of constant
pride and congratulation among the Lyonnais; and accordingly the English
could not stand their competition any where. At that time, the
disadvantage on English silk goods, compared to French, was estimated in
foreign markets at 40 per cent.; of late years it certainly does not
exceed 20, notwithstanding the many peculiar facilities which France
enjoys for this her favourite staple.

The silkworm, called by entomologists _Phalæna bombyx mori_, is, like
its kindred species, subject to four metamorphoses. The egg, fostered by
the genial warmth of spring, sends forth a caterpillar, which, in its
progressive enlargement, casts its skin either three or four times,
according to the variety of the insect. Having acquired its full size in
the course of 25 or 30 days, and ceasing to eat during the remainder of
its life, it begins to discharge a viscid secretion, in the form of
pulpy twin filaments, from its nose, which harden in the air. These
threads are instinctively coiled into an ovoid nest round itself, called
a cocoon, which serves as a defence against living enemies and changes
of temperature. Here it soon changes into the chrysalis or nymph state,
in which it lies swaddled, as it were, for about 15 or 20 days. Then it
bursts its cearments, and comes forth furnished with appropriate wings,
antennæ, and feet, for living in its new element, the atmosphere. The
male and the female moths couple together at this time, and terminate
their union by a speedy death, their whole existence being limited to
two months. The cocoons are completely formed in the course of three or
four days; the finest being reserved as seed worms. From these cocoons,
after an interval of 18 or 20 days, the moth makes its appearance,
perforating its tomb by knocking with its head against one end of the
cocoon, after softening it with saliva, and thus rendering the filaments
more easily torn asunder by its claws. Such moths or aurelias are
collected and placed upon a piece of soft cloth, where they couple and
lay their eggs.

The eggs, or grains as they are usually termed, are enveloped in a
liquid which causes them to adhere to the piece of cloth or paper on
which the female lays them. From this glue they are readily freed, by
dipping them in cold water, and wiping them dry. They are best preserved
in the _ovum_ state at a temperature of about 55° F. If the heat of
spring advances rapidly in April, it must not be suffered to act on the
eggs, otherwise it might hatch the caterpillars long before the mulberry
has sent forth its leaves to nourish them. Another reason for keeping
back their incubation is, that they may be hatched together in large
broods, and not by small numbers in succession. The eggs are made up
into small packets, of an ounce, or somewhat more, which in the south of
France are generally attached to the girdles of the women during the
day, and placed under their pillows at night. They are, of course,
carefully examined from time to time. In large establishments, they are
placed in an appropriate stove-room, where they are exposed to a
temperature gradually increased till it reaches the 86th degree of
Fahrenheit’s scale, which term it must not exceed. Aided by this heat,
nature completes her mysterious work of incubation in eight or ten days.
The teeming eggs are now covered with a sheet of paper pierced with
numerous holes, about one-twelfth of an inch in diameter. Through these
apertures the new-hatched worms creep upwards instinctively, to get at
the tender mulberry leaves strewed over the paper.

The nursery where the worms are reared, is called by the French a
_magnanière_; it ought to be a well-aired chamber, free from damp,
excess of cold or heat, rats and other vermin. It should be ventilated
occasionally, to purify the atmosphere from the noisome emanations
produced by the excrements of the caterpillars and the decayed leaves.
The scaffolding of the wicker-work shelves should be substantial; and
they should be from 15 to 18 inches apart. A separate small apartment
should be allotted to the sickly worms. Immediately before each
moulting, the appetite of the worms begins to flag; it ceases altogether
at that period of cutaneous metamorphosis, but revives speedily after
the skin is fairly cast, because the internal parts of the animal are
thereby allowed freely to develop themselves. At the end of the second
age, the worms are half an inch long; and should then be transferred
from the small room in which they were first hatched, into the proper
apartment where they are to be brought to maturity and set to spin
their balls. On occasion of changing their abode, they must be well
cleansed from the litter, laid upon beds of fresh leaves, and supplied
with an abundance of food every six hours in succession. In shifting
their bed, a piece of network being laid over the wicker plates, and
covered with leaves, the worms will creep up over them; when they may be
transferred in a body upon the net. The litter, as well as the sickly
worms, may thus be readily removed, without handling a single healthy
one. After the third age, they may be fed with entire leaves; because
they are now exceedingly voracious, and must not be subsequently stinted
in their diet. The exposure of chloride of lime, spread thin upon
plates, to the air of the _magnanière_, has been found useful in
counteracting the tendency which sometimes appears of an epidemic
disease among the silkworms, from the fetid exhalations of the dead and
dying.

When they have ceased to eat, either in the fourth or fifth age,
agreeably to the variety of the _bombyx_, and when they display the
spinning instinct by crawling up among the twigs of heath, &c., they are
not long of beginning to construct their cocoons, by throwing the thread
in different directions, so as to form the floss, filoselle, or outer
open network, which constitutes the _bourre_ or silk for carding and
spinning.

The cocoons destined for filature, must not be allowed to remain for
many days with the worms alive within them; for should the chrysalis
have leisure to grow mature or come out, the filaments at one end would
be cut through, and thus lose almost all their value. It is therefore
necessary to extinguish the life of the animal by heat, which is done
either by exposing the cocoons for a few days to sunshine, by placing
them in a hot oven, or in the steam of boiling water. A heat of 202° F.
is sufficient for effecting this purpose, and it may be best
administered by plunging tin cases filled with the cocoons into water
heated to that pitch.

80 pounds French (88 Eng.) of cocoons, are the average produce from one
ounce of eggs, or 100 from one ounce and a quarter; but M. Folzer of
Alsace obtained no less than 165 pounds. The silk obtained from a cocoon
is from 750 to 1150 feet long. The varnish by which the coils are glued
slightly together, is soluble in warm water.

The silk husbandry, as it may be called, is completed in France within
six weeks from the end of April, and thus affords the most rapid of
agricultural returns, requiring merely the advance of a little capital
for the purchase of the leaf. In buying up cocoons, and in the filature,
indeed, capital may be often laid out to great advantage. The most
hazardous period in the process of breeding the worms, is at the third
and fourth moulting; for upon the 6th day of the third age, and the
seventh day of the fourth, they in general eat nothing at all. On the
first day of the fourth age, the worms proceeding from one ounce of eggs
will, according to Bonafons, consume upon an average twenty-three pounds
and a quarter of mulberry leaves; on the first of the fifth age, they
will consume forty-two pounds; and on the sixth day of the same age,
they acquire their maximum voracity, devouring no less than 223 pounds.
From this date their appetite continually decreases, till on the tenth
day of this age they consume only fifty-six pounds. The space which they
occupy upon the wicker tables, being at their birth only nine feet
square, becomes eventually 239 feet. In general the more food they
consume, the more silk will they produce.

A mulberry-tree is valued, in Provence, at from 6_d._ to 10_d._; it is
planted out of the nursery at four years of age; it is begun to be
stripped in the fifth year, and affords an increasing crop of leaves
till the twentieth. It yields from 1 cwt. to 30 cwt. of leaves,
according to its magnitude and mode of cultivation. One ounce of
silkworm eggs is worth in France about 2-1/2 francs; it requires for its
due development into cocoons about 15 cwt. of mulberry leaves, which
cost upon an average 3 francs per cwt. in a favourable season. One ounce
of eggs is calculated, as I have said, to produce from 80 to 100 pounds
of cocoons, of the value of 1 fr. 52 centimes per pound, or 125 francs
in whole. About 8 pounds of reeled raw silk, worth 18 francs a pound,
are obtained from these 100 pounds of cocoons.

There are three denominations of raw silk; viz., organzine, _trame_
(shute or tram), and floss. Organzine serves for the warp of the best
silk stuffs, and is considerably twisted; tram is made usually from
inferior silk, and is very slightly twisted, in order that it may spread
more, and cover better in the weft; floss, or _bourre_, consists of the
shorter broken silk, which is carded and spun like cotton. Organzine and
trame may contain from 3 to 30 twin filaments of the worm; the former
possesses a double twist, the component filaments being first twisted in
one direction, and the compound thread in the opposite; the latter
receives merely a slender single twist. Each twin filament gradually
diminishes in thickness and strength, from the surface of the cocoon,
where the animal begins its work in a state of vigour, to the centre,
where it finishes it, in a state of debility and exhaustion; because it
can receive no food from the moment of its beginning to spin by spouting
forth its silky substance. The winder is attentive to this progressive
attenuation, and introduces the commencement of some cocoons to
compensate for the termination of others. The quality of raw silk
depends, therefore, very much upon the skill and care bestowed upon its
filature. The softest and purest water should be used in the cocoon
kettle.

The quality of the raw silk is determined by first winding off 400 ells
of it, equal to 475 metres, round a drum one ell in circumference, and
then weighing that length. The weight is expressed in grains, 24 of
which constitute one denier; 24 deniers constitute one ounce; and 16
ounces make one pound, _poids de marc_. This is the Lyons rule for
valuing silk. The weight of a thread of raw silk 400 ells long, is two
grains and a half, when five twin filaments have been reeled and
associated together.

Raw silk is so absorbent of moisture, that it may be increased ten per
cent. in weight by this means. This property has led to falsifications;
which are detected by enclosing weighed portions of the suspected silk
in a wire-cloth cage, and exposing it to a stove-heat of about 78° F.
for 24 hours, with a current of air. The loss of weight which it thereby
undergoes, demonstrates the amount of the fraud. There is an office in
Lyons called the _Condition_, where this assay is made, and by the
report of which the silk is bought and sold. The law in France requires,
that all the silk tried by the _Condition_ must be worked up into
fabrics in that country.

In the Journal of the Asiatic Society of Bengal, for January, 1837,
there are two very valuable papers upon silkworms; the first, upon those
of Assam, by Mr. Thomas Hugon, stationed at Nowgong; the second by Dr.
Heifer, upon those which are indigenous to India. Besides the _Bombyx
mori_, the Doctor enumerates the following seven species, formerly
unknown:--1. The wild silkworm of the central provinces, a moth not
larger than the _Bombyx mori_. 2. The Joree silkworm of Assam, _Bombyx
religiosæ_, which spins a cocoon of a fine filament, with much lustre.
It lives upon the pipul tree (_Ficus religiosa_), which abounds in
India, and ought therefore to be turned to account in breeding this
valuable moth. 3. _Saturnia silhetica_, which inhabits the cassia
mountains in Silhet and Dacca, where its large cocoons are spun into
silk. 4. A still larger _Saturnia_, one of the greatest moths in
existence, measuring ten inches from the one end of the wing to the
other; observed by Mr. Grant, in _Chirra Punjee_. 5. _Saturnia paphia_,
or the Tusseh silkworm, is the most common of the native species, and
furnishes the cloth usually worn by Europeans in India. It has not
hitherto been domesticated, but millions of its cocoons are annually
collected in the jungles, and brought to the silk factories near
Calcutta and Bhagelpur. It feeds most commonly on the hair-tree
(_Zizyphus jujuba_), but it prefers the _Terminalia alata_, or Assam
tree, and the _Bombax heptaphyllum_. It is called _Koutkuri mooga_, in
Assam. 6. Another _Saturnia_, from the neighbourhood of Comercolly. 7.
_Saturnia assamensis_, with a cocoon of a yellow-brown colour, different
from all others, called _mooga_, in Assam; which, although it can be
reared in houses, thrives best in the open air upon trees, of which
seven different kinds afford it food. The _Mazankoory mooga_, which
feeds on the Adakoory tree, produces a fine silk, which is nearly white,
and fetches 50 per cent. more than the fawn-coloured. The trees of the
first year’s growth produce by far the most valuable cocoons. The mooga
which inhabits the soom-tree, is found principally in the forests of the
plains, and in the villages. The tree grows to a large size, and yields
three crops of leaves in the year. The silk is of a light fawn colour,
and ranks next in value to the Mazankoory. There are generally five
breeds of mooga worms in the year; 1. in January and February; 2. in May
and June; 3. in June and July; 4. in August and September; 5. in October
and November; the first and last being the most valuable.

The Assamese select for breeding, such cocoons only as have been begun
to be formed in the largest number on the same day, usually the second
or third after the commencement; those which contain males being
distinguishable by a more pointed end. They are put in a closed basket
suspended from the roof; the moths, as they come forth, having room to
move about, after a day, the females (known only by their large body)
are taken out, and tied to small wisps of thatching-straw, selected
always from over the hearth, its darkened colour being thought more
acceptable to the insect. If out of a batch, there should be but few
males, the wisps with the females tied to them are exposed outside at
night; and the males thrown away in the neighbourhood find their way to
them. These wisps are hung upon a string tied across the roof, to keep
them from vermin. The eggs laid after the first three days are said to
produce weak worms. The wisps are taken out morning and evening, and
exposed to the sunshine, and in ten days after being laid, a few of them
are hatched. The wisps being then hung up to the tree, the young worms
find their way to the leaves. The ants, whose bite is fatal to the worm
in its early stages, are destroyed by rubbing the trunk of the tree with
molasses, and tying dead fish and toads to it, to attract these
rapacious insects in large numbers, when they are destroyed with fire; a
process which needs to be repeated several times. The ground under the
trees is also well cleared, to render it easy to pick up and replace the
worms which fall down. They are prevented from coming to the ground by
tying fresh plantain-leaves round the trunk, over whose slippery surface
they cannot crawl; and they are transferred from exhausted trees to
fresh ones, on bamboo platters tied to long poles. The worms require to
be constantly watched and protected from the depredations of both day
and night birds, as well as rats and other vermin. During their
moultings, they remain on the branches; but when about beginning to
spin, they come down the trunk, and being stopped by the
plantain-leaves, are there collected in baskets, which are afterwards
put under bunches of dry leaves, suspended from the roof, into which the
worms crawl, and form their cocoons--several being clustered together:
this accident, due to the practice of crowding the worms together, which
is most injudicious, rendering it impossible to wind off their silk in
continuous threads, as in the filatures of Italy, France, and even
Bengal. The silk is, therefore, spun like flax, instead of being unwound
in single filaments. After four days the proper cocoons are selected for
the next breed, and the rest are uncoiled. The total duration of a breed
varies from 60 to 70 days; divided into the following periods:--

  Four moultings, with one day’s illness attending each     20
  From fourth moulting to beginning of cocoon               10
  In the cocoon 20, as a moth 6, hatching of eggs 10        36
                                                            --
                                                            66

On being tapped with the finger, the body renders a hollow sound; the
quality of which shows whether they have come down for want of leaves on
the tree, or from their having ceased feeding.

As the chrysalis is not soon killed by exposure to the sun, the cocoons
are put on stages, covered up with leaves, and exposed to the hot air
from grass burned under them; they are next boiled for about an hour in
a solution of the potash, made from incinerated rice-stalks; then taken
out, and laid on cloth folded over them to keep them warm. The floss
being removed by hand, they are then thrown into a basin of hot water to
be unwound; which is done in a very rude and wasteful way.

The plantations for the mooga silkworm in Lower Assam, amount to 5000
acres, besides what the forests contain; and yield 1500 maunds of 84
lbs. each per annum. Upper Assam is more productive.

The cocoon of the _Koutkuri mooga_ is of the size of a fowl’s egg. It is
a wild species, and affords filaments much valued for fishing-lines. See
SILKWORM GUT.

8. The _Arrindy_, or _Eria_ worm, and moth, is reared over a great part
of Hindustan, but entirely within doors. It is fed principally on the
_Hera_, or _Palma christi_ leaves, and gives sometimes 12 broods of spun
silk in the course of a year. It affords a fibre which looks rough at
first; but when woven, becomes soft and silky, after repeated washings.
The poorest people are clothed with stuff made of it, which is so
durable as to descend from mother to daughter. The cocoons are put in a
closed basket, and hung up in the house, out of reach of rats and
insects. When the moths come forth, they are allowed to move about in
the basket for twenty-four hours; after which the females are tied to
long reeds or canes, twenty or twenty-five to each, and these are hung
up in the house. The eggs that are laid the first three days, amounting
to about 200, alone are kept; they are tied up in a cloth, and suspended
to the roof till a few begin to hatch. These eggs are white, and of the
size of turnip-seed. When a few of the worms are hatched, the cloths are
put on small bamboo platters hung up in the house, in which they are fed
with tender leaves. After the second moulting, they are removed to
bunches of leaves suspended above the ground, beneath which a mat is
laid to receive them when they fall. When they cease to feed, they are
thrown into baskets full of dry leaves, among which they form their
cocoons, two or three being often found joined together. Upon this
injudicious practice I have already animadverted.

9. The _Saturnia trifenestrata_, has a yellow cocoon of a remarkably
silky lustre. It lives on the soom-tree in Assam, but seems not to be
much used.

[Illustration: 973 974]

The mechanism of the silk filature, as lately improved in France, is
very ingenious. _Figs._ 973. and 974. exhibit it in plan and
longitudinal view. _a_ is an oblong copper basin containing water heated
by a stove or by steam. It is usually divided by transverse partitions
into several compartments, containing 20 cocoons, of which there are 5
in one group, as shown in the figure. _b_, _b_, are wires with hooks or
eyelets at their ends, through which the filaments run, apart, and are
kept from ravelling. _c_, _c_, the points where the filaments cross and
rub each other, on purpose to clean their surfaces. _d_, is a spiral
groove, working upon a pin point, to give the traverse motion
alternately to right and left, whereby the thread is spread evenly over
the surface of the reel _e_. _f_, _f_, are the pulleys, which by means
of cords transmit the rotatory movement of the cylinder _d_, to the reel
_e_. _g_, is a friction lever or tumbler, for lightening or slackening
the endless cord, in the act of starting or stopping the winding
operation. Every apartment of a large filature contains usually a series
of such reels as the above, all driven by one prime mover; each of
which, however, may by means of the tumbling lever be stopped at
pleasure. The reeler is careful to remove any slight adhesions, by the
application of a brush in the progress of her work.

The expense of reeling the excellent Cevennes silk is only 3 francs and
50 centimes per Alais pound; from 4 to 5 cocoons going to one thread.
That pound is 92 hundredths of our avoirdupois pound. In Italy, the cost
of reeling silk is much higher, being 7 Italian livres per pound, when 3
to 4 cocoons go to the formation of one thread; and 6 livres when there
are from 4 to 5 cocoons. The first of these raw silks will have a
_titre_ of 20 to 24 deniers; the last, of 24 to 28. If 5 to 6 cocoons go
to one thread, the titre will be from 26 to 32 deniers, according to the
quality of the cocoons. The Italian livre is worth 7-1/2_d._ English.
The woman employed at the kettle receives one livre and five sous per
day; and the girl who turns the reel, gets thirteen sous a day; both
receiving board and lodging in addition. In June, July, and August, they
work 16 hours a day, and then they wind a _rubo_ or ten pounds weight of
cocoons, which yield from 1-5th to 1-6th of silk, when the quality is
good. The whole expenses amount to from 6 to 7 livres upon every ten
pounds of cocoons; which is about 2_s._ 8_d._ per English pound of raw
silk.

The raw silk, as imported into this country in hanks from the filatures,
requires to be regularly wound upon bobbins, doubled, twisted, and
reeled in our silk-mills. These processes are called _throwing_ silk,
and their proprietors are called silk _throwsters_; terms probably
derived from the appearance of swinging or tossing which the silk
threads exhibit during their rapid movements among the machinery of the
mills.

A representation of a French mill for throwing silk, is given in the
_Dictionnaire Technologique_, under the article _Moulinage de Soie_. But
it is a most awkward, operose, and defective piece of machinery, quite
unworthy of being presented to my readers. It was in Manchester that
throwing-mills received the grand improvement upon the antient Italian
plan, which had been originally introduced into this country by Sir
Thomas Lombe, and erected at Derby. That improvement is chiefly due to
the eminent factory engineers, Messrs. Fairbairn and Lillie, who
transferred to silk the elegant mechanism of the throstle, so well known
in the cotton trade. Still, throughout the silk districts of France the
throwing mills are generally small, not many of them turning off more
than 1000 pounds of organzine per annum, and not involving 5000_l._ of
capital. The average price of throwing organzine in that country, where
the throwster is not answerable for loss, is 7 francs; of throwing
trame, from 4 fr. to 5 fr. (per kilogramme?) Where the throwster is
accountable for loss, the price is from 10 fr. to 11 fr. for organzine,
and from 6 to 7 for trame. In Italy, throwing adds 3_s._ 9_d._ to the
price of raw silk, upon an average. I should imagine, from the
perfection and speed of the silk-throwing machinery in this country, as
about to be described, that the cost of converting a pound of raw silk
either into organzine or _trame_ must be considerably under any of the
above sums.

SILK-THROWING MILL.

[Illustration: 975]

The first process to which the silk is subjected, is winding the skeins,
as imported, off upon bobbins. The mechanism which effects this winding
off and on, is technically called the _engine_, or swift. The bobbins to
which the silk is transferred, are wooden cylinders, of such thickness
as may not injure the silk by sudden flexure, and which may also receive
a great length of thread without having their diameter materially
increased, or their surface velocity changed. _Fig._ 975. is an end view
of the silk-throwing machine, or _engine_, in which the two large
hexagonal reels, called swifts, are seen in section, as well as the
table between them, to which the bobbins and impelling mechanism are
attached. The skeins are put upon these reels, from which the silk is
gradually unwound by the traction of the revolving bobbins. One
principal object of attention, is to distribute the thread over the
length of the bobbin-cylinder in a spiral or oblique direction, so that
the end of the slender semi-transparent thread may be readily found when
it breaks. As the bobbins revolve with uniform velocity, they would soon
wind on too fast, were their diameters so small at first as to become
greatly thicker when they are filled. They are therefore made large, are
not covered thick, but are frequently changed. The motion is
communicated to that end of the engine shown in the figure.

The wooden table A, shown here in cross section, is sometimes of great
length, extending 20 feet, or more, according to the size of the
apartment. Upon this the skeins are laid out. It is supported by the two
strong slanting legs B, B, to which the bearings of the light reel C are
made fast. These reels are called _swifts_, apparently by the same
etymological casuistry as _lucus à non lucendo_; for they turn with
reluctant and irregular slowness; yet they do their work much quicker
than any of the old apparatus, and in this respect may deserve their
name. At every eighth or tenth leg there is a projecting horizontal
piece D, which carries at its end another horizontal bar _a_, called the
knee rail, at right angles to the former. This protects the slender
reels or swifts from the knees of the operatives.

These swifts have a strong wooden shaft _b_, with an iron axis passing
longitudinally through it, round which they revolve, in brass bearings
fixed near to the middle of the legs B. Upon the middle of the shaft
_b_, a loose ring is hung, shown under _c_, in _fig._ 976., to which a
light weight _d_, is suspended, for imparting friction to the reel, and
thus preventing it from turning round, unless it be drawn with a gentle
force, such as the traction of the thread in the act of winding upon the
bobbin.

[Illustration: 976 977]

_Fig._ 976. is a front view of the engine. B, B, are the legs, placed at
their appropriate distances (scale 1-1/2 inch to the foot); C, C, are
the swifts. By comparing _figs._ 975. and 976., the structure of the
swifts will be fully understood. From the wooden shaft _b_, six slender
wooden (or iron) spokes _e_, _e_, proceed, at equal angles to each
other; which are bound together by a cord _f_, near their free ends,
upon the transverse line _f_ of which cord, the silk thread is wound, in
a hexagonal form; due tension being given to the circumferential cords,
by sliding them out from the centre. Slender wooden rods are set
between each pair of spokes, to stay them, and to keep the cord tight. E
is one of the two horizontal shafts, placed upon each side of the
_engine_, to which are affixed a number of light iron pulleys _g_, _g_
(shown on a double scale in _fig._ 977.) These serve, by friction, to
drive the bobbins which rest upon their peripheries.

[Illustration: 981]

To the table A, _fig._ 975., are screwed the light cast-iron
slot-bearings I, I, wherein the horizontal spindles or skewers rest,
upon which the bobbins revolve. The spindles (see F, _fig._ 981.) carry
upon one end a little wooden pulley _h_, whereby they press and revolve
upon the larger driving pulleys _g_, of the shaft E. These pulleys are
called _stars_ by our workmen. The other ends of the spindles, or
skewers, are cut into screws, for attaching the swivel nuts _i_ (_fig._
981.), by which the bobbins K, K, are made fast to their respective
spindles. Besides the slots, above described, in which the spindles rest
when their friction pulleys _h_, are in contact with the moving stars
_g_, there is another set of slots in the bearings, into which the ends
of the spindles may be occasionally laid, so as to be above the line of
contact of the rubbing periphery of the star _g_, in case the thread of
any bobbin breaks. Whenever the girl has mended the thread, she replaces
the bobbin-spindle in its deeper slot-bearings, thereby bringing its
pulley once more into contact with the star, and causing it to revolve.

G is a long ruler or bar of wood, which is supported upon every eighth
or twelfth leg B, B. (The figure being, for convenience of the page,
contracted in length, shows it at every sixth leg.) To the edge of that
bar the smooth glass rods _k_, are made fast, over which the threads
glide from the swifts, in their way to the bobbins. H is the guide bar,
which has a slow traverse or seesaw motion, sliding in slots at the top
of the legs B, where they support the bars G. Upon the guide bar H, the
guide pieces _l_, _l_, are made fast. These consist of two narrow, thin,
upright plates of iron, placed endwise together, their contiguous edges
being smooth, parallel, and capable of approximation to any degree by a
screw, so as to increase or diminish at pleasure the ordinary width of
the vertical slit that separates them. Through this slit the silk thread
must pass, and, if rough or knotty, will be either cleaned or broken; in
the latter case, it is neatly mended by the attendant girl.

[Illustration: 978 979 980 982]

The motions of the various parts of the _engine_ are given as follows.
Upon the end of the machine, represented in _fig._ 975., there are
attached to the shafts E (_fig._ 976.), the bevel wheels 1 and 2, which
are set in motion by the bevel wheels 3 and 4, respectively. These
latter wheels are fixed upon the shaft _m_, _fig._ 975. _m_ is moved by
the main steam shaft which runs parallel to it, and at the same height,
through the length of the _engine_ apartment, so as to drive the whole
range of the machines. 5 is a loose wheel or pulley upon the shaft _m_,
working in geer with a wheel upon the steam shaft, and which may be
connected by the clutch _n_, through the hand lever or geering rod _o_
(_figs._ 975. and 976.), when the engine is to be set at work. 6 is a
spur wheel upon the shaft _m_, by which the stud wheel 7, is driven, in
order to give the traverse motion to the guide bar H. This wheel is
represented, with its appendages, in double size, _figs._ 979. and 980.,
with its boss upon a stud _p_, secured to the bracket _q_. In an
eccentric hole of the same boss, another stud _r_, revolves, upon which
the little wheel _s_, is fixed. This wheel _s_, is in geer with a pinion
cut upon the end of the fixed stud _p_; and upon it is screwed the
little crank _t_, whose collar is connected by two rods _u_ (_figs._
975. and 976.), to a cross-piece _v_, which unites the two arms _w_,
that are fixed upon the guide bar H, on both sides of the machine. By
the revolution of wheel 7, the wheel _s_ will cause the pinion of the
fixed stud _p_ to turn round. If that wheel bear to the pinion the
proportion of 4 to 1, then the wheel _s_ will make, at each revolution
of the wheel 7, one-fourth of a revolution; whereby the crank _t_ will
also rotate through one-fourth of a turn, so as to be brought nearer to
the centre of the stud, and to draw the guide bar so much less to one
side of its mean position. At the next revolution of wheel 7, the crank
_t_ will move through another quadrant, and come still nearer to the
central position, drawing the guide bars still less aside, and therefore
causing the bobbins to wind on more thread in their middle than towards
their ends. The contrary effect would ensue, were the guide bars moved
by a single or simple crank. After four revolutions of the wheel 7, the
crank _t_ will stand once more as shown in _fig._ 980., having moved the
bar H through the whole extent of its traverse. The bobbins, when
filled, have the appearance represented in _fig._ 982.; the thread
having been laid on the mall the time in diagonal lines, so as never to
coincide with each other.

_Doubling_ is the next operation of the silk throwster. In this process,
the threads of two or three of the bobbins, filled as above, are wound
together in contact upon a single bobbin. An ingenious device is here
employed to stop the winding-on the moment that one of these parallel
threads happens to break. Instead of the swifts or reels, a creel is
here mounted for receiving the bobbins from the former machine, two or
three being placed in one line over each other, according as the threads
are to be doubled or trebled. Though this machine is in many respects
like the _engine_, it has some additional parts, whereby the bobbins are
set at rest, as above mentioned, when one of the doubling threads gets
broken.

[Illustration: 983]

_Fig._ 983. is an end view, from which it will be perceived that the
machine is, like the preceding, a double one, with two working sides.

[Illustration: 984]

_Fig._ 984. is a front view of a considerable portion of the machine.

[Illustration: 985]

_Fig._ 985. shows part of a cross section, to explain minutely the mode
of winding upon a single bobbin.

[Illustration: 986]

_Fig._ 986. is the plan of the parts shown in _fig._ 985.; these two
figures being drawn to double the scale of _figs._ 983. and 984.

A, A, _figs._ 983. and 984. are the end frames, connected at their tops
by a wooden stretcher, or _bar-beam_, _a_, which extends through the
whole length of the machine; this bar is shown also in _figs._ 985. and
986.

B, B, are the creels upon each side of the machine, or bobbin bearers,
resting upon wooden beams or boards, made fast to the arms or brackets
C, about the middle of the frames A.

[Illustration: 987]

D, D, are two horizontal iron shafts, which pervade the whole machine,
and carry a series of light movable pulleys, called _stars_, _c_, _c_,
(_figs._ 985, 986.) which serve to drive the bobbins E, E, whose fixed
pulleys rest upon their peripheries, and are therefore turned simply by
friction. These bobbins are screwed by swivel nuts _e_, _e_, upon
spindles, as in the silk engine. Besides the small friction pulley or
boss, _d_, seen best in _fig._ 986., by which they rest upon the star
pulleys _c_, _c_, a little ratchet wheel _f_, is attached to the other
end of each bobbin. This is also shown by itself at _f_, in _fig._ 987.

The spindles with their bobbins revolve in two slot-bearings F, F,
_fig._ 986., screwed to the bar-beam _a_, which is supported by two or
three intermediate upright frames, such as A´. The slot-bearings F, have
also a second slot, in which the spindle with the bobbin is laid at
rest, out of contact of the _star_ wheel, while its broken thread is
being mended. G is the guide bar (to which the cleaner slit pieces _g_,
_g_, are attached), for making the thread traverse to the right and the
left, for its proper distribution over the surface of the bobbin. The
guide bar of the doubling machine is moved with a slower traverse than
in the engine; otherwise, in consequence of the different obliquities of
the paths, the single threads would be readily broken, _h_, _h_, is a
pair of smooth rods of iron or brass, placed parallel to each of the two
sides of the machine, and made fast to the standards H, H, which are
screwed to brackets projecting from the frames A, A´. Over these rods
the silk threads glide, in their passage to the guide wires _g_, _g_,
and the bobbins E, E.

I, I, is the _lever board_ upon each side of the machine, upon which the
slight brass bearings or fulcrums _i_, _i_, one for each bobbin in the
creel, are made fast. This board bears the _balance-lever_ _k_, _l_,
with the _fullers_ _n_, _n_, _n_, which act as dexterous fingers, and
stop the bobbin from winding-on the instant a thread may chance to
break. The levers _k_, _l_, swing upon a fine wire axis, which passes
through their props _i_, _i_, their arms being shaped rectangularly, as
shown at _k_, _k´_, _fig._ 986. The arm _l_, being heavier than the arm
_k_, naturally rests upon the ridge bar _m_, of the lever board I. _n_,
_n_, _n_, are three wires, resting at one of their ends upon the axis of
the fulcrum _i_, _i_, and having each of their other hooked ends
suspended by one of the silk threads, as it passes over the front steel
rod _h_, and under _h´_. These faller wires, or stop fingers, are
guided truly in their up-and-down motions with the thread, by a
cleaner-plate _o_, having a vertical slit in its middle. Hence, whenever
any thread happens to break, in its way to a winding-on bobbin E, the
wire _n_, which hung by its eyelet end to that thread, as it passed
through between the steel rods in the line of _h_, _h´_, falls upon the
lighter arm of the balance lever _k_, _l_, weighs down that arm _k_,
consequently jerks up the arm _l_, which pitches its tip or end into one
of the three notches of the ratchet or catch wheel _f_ (_figs._ 986. and
987.), fixed to the end of the bobbin. Thus its motion is
instantaneously arrested, till the girl has had leisure to mend the
thread, when she again hangs up the faller wire _n_, and restores the
lever _k_, _l_, to its horizontal position. If, meanwhile, she took
occasion to remove the winding bobbin out of the sunk slot-bearing,
where pulley _d_ touches the _star_ wheel _c_, into the right-hand upper
slot of repose, she must now shift it into its slot of rotation.

The motions are given to the doubling machine in a very simple way. Upon
the end of the framing, represented in _fig._ 983., the shafts D, D,
bear two spur wheels 1 and 2, which work into each other. To the wheel
1, is attached the bevel wheel 3, driven by another bevel wheel 4
(_fig._ 984.), fixed to a shaft that extends the whole length of the
apartment, and serves, therefore, to drive a whole range of machines.
The wheel 4 may be put in geer with the shaft, by a clutch and
geer-handle, as in the silk _engine_, and thereby it drives two shafts,
by the one transmitting its movement to the other.

The traverse motion of the guide bar G, is effected as follows:--Upon
one of the shafts D, there is a bevel wheel 5, driving the bevel wheel
6, upon the top of the upright shaft _p_ (_fig._ 984., to the right of
the middle); whence the motion is transmitted to the horizontal shaft
_q_, below, by means of the bevel wheels 7 and 8. Upon this shaft _q_,
there is a heart-wheel _r_, working against a roller which is fixed to
the end of the lever _s_, whose fulcrum is at _t_, _fig._ 983. The other
end of the lever _s_, is connected by two rods (shown by dotted lines in
_fig._ 984.) to a brass piece which joins the arms _u_ (_fig._ 984.), of
the guide bars G. To the same cross piece a cord is attached, which goes
over a roller _v_, and suspends a weight _w_, by means of which the
lever _s_, is pressed into contact with the heart-wheel _r_. The fulcrum
_t_, of the lever _s_, is a shaft which is turned somewhat eccentric,
and has a very slow rotatory motion. Thus the guide bar, after each
traverse, necessarily winds the silk in variable lines, to the side of
the preceding threads.

The motion is given to this shaft in the following way. Upon the
horizontal shaft _q_, there is a bevel wheel _g_ (_figs._ 983. and
984.), which drives the wheel 10 upon the shaft _x_; on whose upper end,
the worm _y_ works in the wheel 11, made fast to the said eccentric
shaft _t_; round which the lever _s_, swings or oscillates, causing the
guide bars to traverse.

_The spinning silk-mill._--The machine which twists the silk threads,
either in their single or doubled state, is called the spinning mill.
When the raw singles are first twisted in one direction, next doubled,
and then twisted together in the opposite direction, an exceedingly
wiry, compact thread, is produced, called _organzine_. In the spinning
mill, either the singles or the doubled silk, while being unwound from
one set of bobbins, and wound upon another set, is subjected to a
regular twisting operation; in which process the thread is conducted as
usual through guides, and coiled diagonally upon the bobbins by a proper
mechanism.

[Illustration: 988]

_Fig._ 988. exhibits an end view of the spinning mill; in which four
working lines are shown; two tiers upon each side, one above the other.
Some spinning mills have three working tiers upon each side; but as the
highest tier must be reached by a ladder or platform, this construction
is considered by many to be injudicious.

[Illustration: 989]

_Fig._ 989. is a front view, where, as in the former figure, the two
working lines are shown.

[Illustration: 990]

_Fig._ 990. is a cross section of a part of the machine, to illustrate
the construction and play of the working parts; _figs._ 996, 997. are
other views of _fig._ 990.

[Illustration: 991]

_Fig._ 991. shows a single part of the machine, by which the bobbins are
made to revolve.

[Illustration: 992 993]

_Figs._ 992. and 993. show a different mode of giving the traverse to
the guide bars, than that represented in _fig._ 990.

[Illustration: 994]

_Figs._ 994. and 995. show the shape of the full bobbins, produced by
the action of these two different traverse motions.

The upper part of the machine being exactly the same as the under part,
it will be sufficient to explain the construction and operation of one
of them.

A, A, are the end upright frames or standards, between which are two or
three intermediate standards, according to the length of the machine.
They are all connected at their sides by beams B and C, which extend the
whole length of the machines. D, D, are the spindles, whose top bearings
_a_, _a_, are made fast to the beams B, and their bottoms turn in hard
brass steps, fixed to the bar C. These two bars together are called, by
the workmen, the spindle box. The standards A, A, are bound with cross
bars N, N.

_c_, _c_, are the wharves or whorls, turned by a band from the
horizontal tin cylinder in the lines of E, E, _fig._ 988., lying in the
middle line between the two parallel rows of spindles D, D. F, F, are
the bobbins containing the untwisted doubled silk, which are simply
pressed down upon the taper end of the spindles. _d_, _d_, are little
flyers, or forked wings of wire, attached to washers of wood, which
revolve loose upon the tops of the said bobbins F, and round the
spindles. One of the wings is sometimes bent upwards, to serve as a
guide to the silk, as shown by dotted lines in _fig._ 990. _e_, _e_, are
pieces of wood pressed upon the tops of the spindles, to prevent the
flyers from starting off by the centrifugal force. G, are horizontal
shafts bearing a number of little spur wheels _f_, _f_. H, are
slot-bearings, similar to those of the doubling-machine, which are fixed
to the end and middle frames. In these slots, the light square cast-iron
shafts or spindles _g_, _fig._ 989., are laid, on whose end the spur
wheel _h_ is cast; and when the shaft _g_ lies in the front slot of its
bearing, it is in geer with the wheel _f_, upon the shaft G; but when it
is laid in the back slot, it is out of geer, and at rest. See F, F,
_fig._ 986.

Upon these little cast-iron shafts or spindles _g_, _fig._ 991., the
bobbins or blocks I, are thrust, for receiving, by winding-on, the
twisted or spun silk. These blocks are made of a large diameter, in
order that the silk fibres may not be too much bent; and they are but
slightly filled, at each successive charge, lest, by increasing their
diameter too much, they should produce too rapid an increase in the rate
of winding, with proportional diminution in the twist, and risk of
stretching or tearing the silk. They are therefore the more frequently
changed. K, K, are the guide bars, with the guides _i_, _i_, through
which the silk passes, being drawn by the revolving bobbins I, and
delivered or laid on by the flyers _d_, _d_, from the rotatory
twisting-bobbins F. The operation of the machine is therefore simple,
and the motions are given to the parts in a manner equally so.

Upon the shaft of the tin cylinder or drum, exterior to the frame, the
usual fast and loose pulleys, or riggers, L, L´, are mounted, for
driving the whole machine. These riggers are often called steam-pulleys
by the workmen, from their being connected by bands with the
steam-driven shaft of the factory. In order to allow the riggers upon
the shafts of the upper and the under drums to be driven from the same
pulley upon the main shaft, the axis of the under drum is prolonged at
L, L, and supported at its end, directly from the floor, by an upright
bearing. Upon the shafts of the tin cylinders there is also a fly-wheel
M, to equalize the motion. Upon the other ends of these shafts, namely
at the end of the spinning-mill, represented in _fig._ 988., the pinions
1 are fixed, which drive the wheels 3, by means of the intermediate or
carrier wheel 2; called also the plate wheel, from its being hollowed
somewhat like a trencher. 1, is called the change-pinion, because it is
changed for another, of a different size and different number of teeth,
when a change in the velocity of wheels 2 and 3 is to be made. To allow
a greater or smaller pinion to be applied at 1, the wheel 2 is mounted
upon a stud _k_, which is movable in a slot concentric with the axis of
the wheel 3. This slot is a branch from the cross bar N. The smaller the
change-pinion is, the nearer will the stud _k_ approach to the vertical
line joining the centres of wheels 1 and 3; and the more slowly will the
plate wheel 2 be driven. To the spur wheel 3, a bevel wheel 4, is fixed,
with which the other also revolves loose upon a stud. The bevel wheel 5,
upon the shaft _l_, is driven by the bevel wheel 4; and it communicates
motion, by the bevel wheels 6 and 7, to each of the horizontal shafts G,
G, extending along the upper and under tiers of the machine. At the
left-hand side of the top part of _fig._ 988. the two wheels 6 and 7 are
omitted, on purpose to show the bearings of the shaft G, as also the
slot-bearings for carrying the shafts or skewers of the bobbins.

If it be desired to communicate twist in the opposite direction to that
which would be given by the actual arrangement of the wheels, it is
necessary merely to transpose the carrier wheel 2, from its present
position on the right hand of pinion 1, to the left of it, and to drive
the tin cylinder by a crossed or close strap, instead of a straight or
open one.

The traverse motion of the guide is given here in a similar way to that
of the engine, (_fig._ 975.) Near one of the middle or cross-frames of
the machine (see _fig._ 990.) the wheel _f_, in geer with a spur wheel
_h_, upon one of the block-shafts, drives also a spur wheel _m_, that
revolves upon a stud, to which wheel is fixed a bevel wheel _n_, in geer
with the bevel wheel _o_. To wheel _o_, the same mechanism is attached
as was described under _figs._ 979. and 980., and which is here marked
with the same letters.

To the crank-knob _r_, _fig._ 990., a rod _x_, is attached, which moves
or traverses the guide bar belonging to that part of the machine; to
each machine one such apparatus is fitted. In _figs._ 992. and 993.
another mode of traversing the guide bar is shown, which is generally
used for the coarser qualities of silk. Near to one of the middle
frames, one of the wheels _f_, in geer with the spur wheel _m_, and the
bevel wheel _n_, both revolving on one stud, gives motion also to the
wheel _o_, fixed upon a shaft _a´_, at whose other end the elliptical
wheel _b´_ is fixed, which drives a second elliptical wheel _c´_, in
such a way that the larger diameter of the one plays in geer with the
smaller diameter of the other; the teeth being so cut as to take into
each other in all positions. The crank-piece _d´_ is screwed upon the
face of the wheel _c´_, at such a distance from its centre as may be
necessary to give the desired length of traverse motion to the guide bar
for laying the silk spirally upon the blocks. The purpose of the
elliptical wheel is to modify the simple crank motion, which would wind
on more silk at the ends of the bobbins than in their middle, and to
effect an equality of winding-on over the whole surface of the blocks.
In _fig._ 993. the elliptical wheels are shown in front, to illustrate
their mode of operating upon each other. _Fig._ 994. is a block filled
by the motion of the eccentric, _fig._ 900.; and _fig._ 995. is a block
filled by the elliptical mechanism. As the length of the motions of the
bar in the latter construction remains the same during the whole
operation, the silk, as it is wound on the blocks, will slide over the
edges, and thereby produce the flat ends of the barrel in _fig._ 995.
The conical ends of the block (_fig._ 994.) are produced by the
continually shortened motions of the guide bar, as the stud approaches,
in its sun-and-planet rotation, nearer to the general centre.

[Illustration: 996]

[Illustration: 997]

_Figs._ 996, 997. are two different views of the differential mechanism
described under _fig._ 990.

The bent wire _x_, _fig._ 990., is called the guider iron. It is
attached at one end to the pivot of the sun-and-planet wheel-work _t_,
_s_, _o_, and at the other to the guide bar _f_, _f_, _fig._ 989. The
silk threads pass through the guides, as already explained. By the
motion communicated to the guide bar (_guider_), the diamond pattern is
produced, as shown in _fig._ 994.

THE SILK AUTOMATIC REEL.

In this machine, the silk is unwound from the blocks of the
throwing-mill, and formed into hanks for the market. The blocks being of
a large size, would be productive of much friction, if made to revolve
upon skewers thrust through them, and would cause frequent breakage of
the silk. They are, therefore, set with their axes upright upon a board,
and the silk is drawn from their surface, just as the weft is from a cop
in the shuttle. On this account the previous winding-on must be executed
in a very regular manner; and preferably as represented in _fig._ 994.

[Illustration: 998 999]

_Fig._ 998. is a front view of the reel; little more than one-half of it
being shown. _Fig._ 999. is an end view. Here the steam-pulleys are
omitted, for fear of obstructing the view of the more essential parts.
A, A, are the two end framings, connected by mahogany stretchers, which
form the table B, for receiving the bobbins C, C, which are sometimes
weighted at top with a lump of lead, to prevent their tumbling. D is the
reel, consisting of four long laths of wood, which are fixed upon iron
frames, attached to an octagonal wooden shaft. The arm which sustains
one of these laths is capable of being bent inwards, by loosening a
tightening hook, so as to permit the hanks, when finished, to be taken
off, as in every common reel.

The machine consists of two equal parts, coupled together at _a_, to
facilitate the removal of the silk from either half of the reel; the
attendant first lifting the one part, and then the other. E is the guide
bar, which by a traverse motion causes the silk to be wound on in a
cross direction. _b_ and _c_ are the wire guides, and _d_ are little
levers lying upon the cloth-covered guide bar E. The silk in its way
from the block to the reel, passes under these levers, by which it is
cleaned from loose fibres.

On the other end of the shaft of the reel, the spur wheel 1 is fixed,
which derives motion from wheel 2, attached to the shaft of the
steam-pulley F. Upon the same shaft there is a bevel wheel 3, which
impels the wheel 4 upon the shaft _e_; to whose end a plate is attached,
to which the crank _f_ is screwed, in such a way as to give the proper
length of traverse motion to the guide bar E, connected to that crank or
eccentric stud by the jointed rod _g_. Upon the shaft of the
steam-pulleys F, there is a worm or endless screw, to the left of _f_,
_fig._ 999., which works in a wheel 5; attached to the short upright
shaft _h_ (_fig._ 998.). At the end of _h_, there is another worm, which
works in a wheel 6; at whose circumference there is a stud _i_, which
strikes once at every revolution against an arm attached to a bell, seen
to the left of G; thus announcing to the reel-tenter that a measured
length of silk has been wound upon her reel. _e_ is a rod or handle, by
which the fork _l_, with the strap, may be moved upon the fast or loose
pulley, so as to set on or arrest the motion at pleasure.

Throwsters submit their silk to scouring and steaming processes. They
soak the hanks, as imported, in lukewarm soap-water in a tub; but the
bobbins of the twisted single silk from the spinning mill are enclosed
within a wooden chest, and exposed to the opening action of steam for
about ten minutes. They are then immersed in a cistern of warm water,
from which they are transferred to the doubling frame.

The wages of the workpeople in the silk-throwing mills of Italy are
about one half of their wages in Manchester; but this difference is much
more than counterbalanced by the protecting duty of 2_s._ 10_d._ a pound
upon thrown silk, and the superior machinery of our mills. In 1832,
there was a power equal to 342 horses engaged in the silk-throwing mills
of Manchester; and of about 100 in the mills of Derby. The power
employed in the other silk mills of England and Scotland has not been
recorded.

There is a peculiar kind of silk called _marabout_, containing generally
three threads, made from the white Novi raw silk. From its whiteness, it
takes the most lively and delicate colours without the discharge of its
gum. After being made into tram by the single twist upon the spinning
mill, it is reeled into hanks, and sent to the dyer without further
preparation. After being dyed, the throwster re-winds and re-twists it
upon the spinning mill, in order to give it the whipcord hardness which
constitutes the peculiar feature of marabout. The cost of the raw Novi
silk is 19_s._ 6_d._ a pound; of throwing it into tram, 2_s._ 6_d._; of
dyeing, 2_s._; of re-winding and re-twisting, after it has been dyed,
about 5_s._; of waste, 2_s._, or 10 per cent.; the total of which sum is
31_s._; being the price of one pound of marabout in 1832.

An ESTIMATE of the Annual Quantities of SILK produced or exported from
the several Countries in the World, exhibiting also the Countries to
which exported.

  +-------------------+---------------------------+------------+------+
  |Countries whence   |Quantities.                |Countries to|Quan- |
  |exported.          |                           |which ex-   |ti-   |
  |                   |                           |ported.     |ties. |
  +-------------------+---------------------------+------------+------+
  |                   |                           |            |Bales.|
  |Italy exports      |34,000 bales of 225 small  |            |      |
  |                   |       lbs.                |            |      |
  |France produces    |10,500 { 73-1/8 kils., or  |}England    |28,000|
  |India and Bengal   | 9,500 {128-1/2 Vienna lbs.|}France     |22,000|
  |          export   |        162 lbs. English   |            |      |
  |Persia     . .     | 7,500                     |Prussia     | 7,600|
  |China      . .     | 4,000                     |Russia      | 6,400|
  |Asia Minor . .     | 3,500                     |Austria and |      |
  |Levant, Turkey, and|                           |Germany     | 5,000|
  |Archipelago export | 3,500                     |Switzerland | 5,000|
  |Spain      . .     | 1,500                     |            |------|
  |                   |------                     |Total       |74,000|
  |Total              |74,000 bales.              |            |      |
  +-------------------+---------------------------+------------+------+

  _Note._--These estimates exclude the silk manufactured in Italy.

The declared value of the silk manufactures exported from the United
Kingdom in 1836, was 917,822_l._; and in 1837, only 494,569. The deficit
in the last year was owing to the commercial crisis in the United
States; which country took, the preceding year, our silk goods to the
value of 524,301_l._

[Illustration: 1000]


SILKWORM GUT, for angling, is made as follows:--Select a number of the
best and largest silkworms, just when they are beginning to spin; which
is known by their refusing to eat, and having a fine silk thread hanging
from their mouths. Immerse them in strong vinegar, and cover them
closely for twelve hours, if the weather be warm, but two or three hours
longer, if it be cool. When taken out, and pulled asunder, two
transparent guts will be observed, of a yellow green colour, as thick as
a small straw, bent double. The rest of the entrails resembles boiled
spinage, and therefore can occasion no mistake as to the silk-gut. If
this be soft, or break upon stretching it, it is a proof that the worm
has not been long enough under the influence of the vinegar. When the
gut is fit to draw out, the one end of it is to be dipped into the
vinegar, and the other end is to be stretched gently to the proper
length. When thus drawn out, it must be kept extended on a thin piece of
board, by putting its extremities into slits in the end of the wood, or
fastening them to pins, and then exposed in the sun to dry. Thus genuine
silk-gut is made in Spain. From the manner in which it is dried, the
ends are always more or less compressed or attenuated.[53] _Fig._ 1000.
_a_, is the silkworm; _b_, the worm torn asunder; _c_, _c_, the guts;
_d_, _d_, a board slit at the ends, with the gut to dry; _f_, _f_, a
board with wooden pegs, for the same purpose.

  [53] Nobb’s Art of Trolling.


SILVER (_Argent_, Fr.; _Silber_, Germ.;) was formerly called a _perfect_
metal, because heat alone revived its oxide, and because it could pass
unchanged through fiery trials, which apparently destroyed most other
metals. The distinctions, perfect, imperfect, and noble, are now justly
rejected. The bodies of this class are all equal in metallic nature,
each being endowed merely with different relations to other forms of
matter, which serve to characterize it, and to give it a peculiar value.

When pure and planished, silver is the brightest of the metals. Its
specific gravity in the ingot is 10·47; but, when condensed under the
hammer or in the coining press, it becomes 10·6. It melts at a bright
red heat, a temperature estimated by some as equal to 1280° Fahr., and
by others to 22° Wedgewood. It is exceedingly malleable and ductile;
affording leaves not more than 1/100000 of an inch thick, and wire far
finer than a human hair.

By Sickingen’s experiments, its tenacity is, to that of gold and
platinum, as the numbers 19, 15, and 26-1/4; so that it has an
intermediate strength between these two metals. Pure atmospheric air
does not affect silver, but that of houses impregnated with sulphuretted
hydrogen, soon tarnishes it with a film of brown sulphuret. It is
distinguished chemically from gold and platinum by its ready solubility
in nitric acid, and from almost all other metals, by its saline
solutions affording a curdy precipitate with a most minute quantity of
sea salt, or any soluble chloride.

Silver occurs under many forms in nature:--

1. _Native silver_, possesses the greater part of the above properties;
yet, on account of its being more or less alloyed with other metals, it
differs a little in malleability, lustre, density, &c. It sometimes
occurs crystallized in wedge-form octahedrons, in cubes, and
cubo-octahedrons. At other times it is found in dendritic shapes, or
arborescences, resulting from minute crystals implanted upon each other.
But more usually it presents itself in small grains without determinable
form, or in amorphous masses of various magnitude.

The _gangues_ (mineral matrices) of native silver are so numerous, that
it may be said to occur in all kinds of rocks. At one time it appears as
if filtered into their fissures, at another as having vegetated on their
surface, and at a third, as if impasted in their substance. Such
varieties are met with principally in the mines of Peru.

The native metal is found in almost all the silver mines now worked; but
especially in that of Kongsberg in Norway, in carbonate and fluate of
lime, &c.; at Schlangenberg in Siberia, in a sulphate of barytes; at
Allémont, in a ferruginous clay, &c. In the article MINES, I have
mentioned several large masses of native silver that have been
discovered in various localities.

The metals most usually associated with silver in the native alloy, are
gold, copper, arsenic, and iron. At Andreasberg and Guadalcanal it is
alloyed with about 5 per cent. of arsenic. The auriferous native silver
is the rarest; it has a brass-yellow colour.

2. _Antimonial silver._--This rare ore is yellowish-blue; destitute of
malleability; even very brittle; spec. grav. 9·5. It melts before the
blowpipe, and affords white fumes of oxide of antimony; being readily
distinguished from arsenical iron, and arsenical cobalt, by its lamellar
fracture. It consists of from 76 to 84 of silver, and from 24 to 16 of
antimony.

3. _Mixed antimonial silver._--At the blowpipe it emits a strong garlic
smell. Its constituents are, silver 16, iron 44, arsenic 35, antimony 4.
It occurs at Andreasberg.

4. _Sulphuret of silver._--This is an opaque substance, of a dark-gray
or leaden hue; slightly malleable, and easily cut with a knife, when it
betrays a metallic lustre. The silver is easily separated by the
blowpipe. It consist of, 13 of sulphur to 89 of silver, by experiment;
13 to 87 are the theoretic proportions. Its spec. grav. is 6·9. It
occurs crystallized in most silver mines, but especially in those of
Freyberg, Joachimsthal in Bohemia, Schemnitz in Hungary, and Mexico.

5. _Red sulphuret of silver; silver glance._--Its spec. grav. is 5·7. It
contains from 84 to 86 of silver.

6. _Sulphuretted silver, with bismuth._--Its constituents are, lead 35,
bismuth 27, silver 15, sulphur 16, with a little iron and copper. It is
rare.

7. _Antimoniated sulphuret of silver_, the red silver of many
mineralogists, is an ore remarkable for its lustre, colour, and the
variety of its forms. It is friable, easily scraped by the knife, and
affords a powder of a lively crimson red. Its colour in mass, is
brilliant red, dark red, or even metallic reddish-black. It crystallizes
in a variety of forms. Its constituents are,--silver from 56 to 62;
antimony from 16 to 20; sulphur from 11 to 14; and oxygen from 8 to 10.
The antimony being in the state of a purple oxide in this ore, is
reckoned to be its colouring principle. It is found in almost all silver
mines; but principally in those of Freyberg, Sainte-Marie-aux-Mines, and
Guadalcanal.

8. _Black sulphuret of silver_; is blackish, brittle, cellular,
affording globules of silver at the blowpipe. It is found only in
certain mines, at Allémont, Freyberg; more abundantly in the silver
mines of Peru and Mexico. The Spaniards call it _negrillo_.

9. _Chloride of silver, or horn silver._--In consequence of its
semi-transparent aspect, its yellowish or greenish colour, and such
softness that it may be cut with the nail, this ore has been compared to
horn, and may be easily recognised. It melts at the flame of a candle,
and may be reduced when heated along with iron or black flux, which are
distinctive characters. It is seldom crystallized; but occurs chiefly in
irregular forms, sometimes covering the native silver as with a thick
crust, as in Peru and Mexico. Its density is only 4·74.

Chloride of silver sometimes contains 60 or 70 per cent. of clay; and is
then called butter-milk ore, by the German miners. The blowpipe causes
globules of silver to sweat out of it. This ore is rather rare. It
occurs in the mines of Potosi, of Annaberg, Freyberg, Allémont,
Schlangenberg, in Siberia, &c.

10. _Carbonate of silver_, a species little known, has been found
hitherto only in the mine of S. Wenceslas, near Wolfache.

TABLE of the Quantities of SILVER brought into the Market every year, on
an average, from 1790 to 1802.

  +----------------+------------+---------------+------------+
  | Old Continent. |Lbs. Avoird.| New Continent.|Lbs. Avoird.|
  +----------------+------------+---------------+------------+
  |     ASIA.      |            |               |            |
  |Siberia         |     38,500 |Central America|  1,320,000 |
  |    EUROPE.     |            |               |            |
  |Hungary         |     44,000 |South America  |    605,000 |
  |Austrian States |     11,000 |               |            |
  |Hartz and Hessia|     11,000 |               |            |
  |Saxony          |     22,000 |               |            |
  |Norway          |     22,000 |               |            |
  |Sweden         }|            |               |            |
  |France         }|     11,000 |               |            |
  |Spain          }|            |               |            |
  |                |    --------|               |  ----------|
  |Total of the    |            |Total of the   |            |
  |Old Continent   |    159,500 |New Continent  |  1,925,000 |
  +----------------+------------+---------------+------------+

Thus the New Continent furnished twelve times more silver than the Old.
For more detailed statistics of silver, see the end of the article.

The following is Mr. Ward’s description of the treatment of silver ores
in Mexico:--

“After returning from San Augustin,” says he, “I passed the whole of the
afternoon at the _hacienda_ (metallurgic works) of Salgado, in which the
ores of the Valenciana mine are reduced. The _hacienda_, of which a
representation is given below, _fig._ 1001. contains forty-two
crushing-mills, called _arrastres_, and thirty-six stampers. The ore, on
being extracted from the mine, is placed in the hands of the
_pepenadores_, men and women, who break all the larger pieces with
hammers, and after rejecting those in which no metallic particles are
contained, divide the rest into three classes” (inferior, middling, and
rich). “These are submitted to the action of the _morteros_ (stamps),
one of which, of eight stampers, is capable of reducing to powder ten
cargas of ore (each of 350 lbs.) in twenty-four hours. This powder not
being thought sufficiently fine for the quicksilver to act upon with
proper effect, it is transferred from the _morteros_ to the _arrastres_
(crushing-mills, see wood-cut), in which water is used. Each of these
reduces to a fine impalpable metalliferous mud, six quintals (600 lbs.)
of powder in 24 hours. At Guanajuato, where water-power cannot be
obtained, the _arrastres_ are worked by mules (see _fig._ 1001.), which
are kept constantly in motion at a slow pace, and are changed every 6
hours. The grinding-stones, as well as the sides and bottom of the mill
itself, are composed of granite; four blocks of which revolve in each
crushing-mill, attached to cross-bars of wood. This part of the
operation is thought of great importance, for it is upon the perfection
of the grinding that the saving of the quicksilver is supposed in a
great measure to depend, in the subsequent amalgamation. The grinding is
performed usually in a covered shed or gallery which in a large
_hacienda_, like Salgado, from the number of _arrastres_ at work at the
same time, is necessarily of considerable extent.”

[Illustration: 1001 _The Gallera of the Hacienda of Salgado_]

_Fig._ 1002. represents the rude grinding apparatus used at the
_lavaderos_, or gold washings, in Chile. The streamlet of water conveyed
to the hut of the gold washer, is received upon a large rude stone,
whose flat surface has been hollowed out into a shallow basin, and in
the same manner into 3 or 4 others in succession; the auriferous
particles are thus allowed to deposit themselves in these receptacles,
while the lighter earthy atoms, still suspended, are carried off by the
running water. The gold thus collected is mixed with a quantity of
ferruginous black sand and stony matter, which requires the process of
trituration, effected by the very rude and simple _trapiche_ shown in
the figure; consisting of two stones, the under one being about three
feet in diameter, and slightly concave. The upper stone is a large
spherical boulder of syenitic granite, about two feet in diameter,
having on its upper part two iron plugs fixed oppositely, to which is
secured, by lashings of hide, a transverse horizontal pole of _canela_
(cinnamon) _wood_, about 10 feet long; two men seated on the extremities
of this lever, work it up and down alternately, so as to give to the
stone a rolling motion, which is sufficient to crush and grind the
materials placed beneath it. The washings thus ground, are subjected to
the action of running water, upon inclined planes formed of skins, by
which process the siliceous particles are carried off, while a portion
of the ferruginous matter, mixed with the heavier grains of gold, is
extracted by a loadstone; it is again washed, till nothing but pure
gold-dust remain. The whole process is managed with much dexterity; and
if there were much gold to be separated, it would afford very
profitable employment; but generally the small quantity collected is
sufficient only to afford subsistence to a few miserable families.

[Illustration: 1002]

The _trapiche_, _ingenio_, or mill, for grinding the ores of silver, is
a very simple piece of mechanism. A place is chosen where a small
current of water, whose section will present a surface of six inches
diameter, can be brought to a spot where it can fall perpendicularly ten
or twelve feet; at this place a well is built of this depth, about 6
feet in diameter; in its centre is fixed an upright shaft, upon a
central brass pin; it is confined above by a wooden collar. A little
above its foot, the shaft has a small wheel affixed to it, round which
are fixed a number of radiating spokes, shaped at the end somewhat like
cups, and forming altogether a horizontal wheel, four feet in diameter.
Upon the slanting edges of the cups, the water is made to strike with
the force it has acquired in falling down a nearly perpendicular trough,
scooped out of the solid trunk of a tree. This impression makes the
wheel turn with a quick rotatory motion. The upright axis rises about 6
feet above the top of the well, at about half which height is inserted a
small horizontal arm, four feet long, which serves as an axle to a
ponderous mill-stone of granite, of from four to six feet diameter,
which is made to roll on its edge in a circular trough, sometimes made
of the same material, and sometimes of hard wood.

The weight of this quickly rolling stone effects the pulverization of
the ore. In some cases, it is taken out in the dry state, and sifted;
but more generally the separation of the finely ground particles is
accomplished by the action of running water. For this purpose a small
stream is made to trickle into the circular trough, by which the pounded
ore is worked up into a muddy consistence, and the finer particles flow
off with the excess of water, through a notch cut in the margin of the
trough. This fine matter is received in little pools, where the pounded
ore is left to settle; and the clear water being run off, the powder is
removed from the bottom, and carried to the place of amalgamation.

[Illustration: 1003]

The _ingenios_, or stamping-mills, are driven by a small breast
water-wheel, of five feet diameter, and one foot broad. _Fig._ 1003.
will give a sufficient idea of their construction. The long horizontal
shaft, fixed on the axis of the wheel, is furnished with 5 or 6 cams
placed at different situations round the shaft, so as to act in
succession on the projecting teeth of the upright rods or pestles. Each
of these weighs 200 pounds, and works in a corresponding oblong mortar
of stone or wood.

[Illustration: 1004]

The _patio_, or amalgamation floor, _fig._ 1004., is a large flat space,
open to the sky, 312 feet in length, by 236 in breadth, and securely
surrounded by strong walls. It is paved with large unhewn blocks of
porphyry, and is capable of containing 24 _tortas_, or flat circular
collections of _lama_, of about 50 feet diameter, and 7 inches deep,
when the patio is not filled, (but of somewhat smaller dimensions when
nearly so,) ranged in 4 rows, and numbered from the left-hand corner. At
one end a small space is generally set apart for the assays, which are
made each on one monton.

The following description of Mexican amalgamation is given by Captain
Lyon.

A torta of Zacatecas contains 60 montons of 20 quintals each, and is
thus formed:--In the first instance, a square space, of the requisite
size for a torta, is marked out, and enclosed by a number of rough
planks, which are propped in their places on the patio floor by large
stones, and dried horse-dung and dust are piled round their edges to
prevent the escape of the lama. A heap of saltierra (salt mixed with
earthy impurities) is then piled in the centre, in the proportion of 2
fanegas (each = 1·6 English bushels) and a half to the monton, = 150 for
the torta. After this, the lama, or ore ground into a fine paste, is
poured in. When the last or 60th monton is delivered, the saltierra is
shovelled down and well mixed with the lama, by treading it with horses,
and turning it with shovels; after which the preparation is left at rest
for the remainder of the day. On the following day comes the _el
incorporo_. After about one hour’s treading by horses, the magistral or
roasted and pulverized copper ore is mixed with the lama, (the _repaso_
or treading-mill still continuing,) in summer in the proportion of 15
cargas of 12 arrobas (25 lbs. each) to the torta, if the ore be of 6
marcs to the monton, and in winter in only half the quantity. For it is
a singular fact, that in summer the mixture cools, and requires more
warmth; while in winter it acquires of itself additional heat. With
poorer ores, as for instance those of 4 marcs to the monton, 12 cargas
are applied in summer, and 6 in winter. From November to February, lime
is also occasionally used to cool the lama, in the proportion of about a
peck per monton.

The _repaso_, or treading out, is continued by six horses, which are
guided by one man, who stands in the lama, and directs them all by
holding all their long halters. This operation is much more effectual in
a morning than an evening, and occupies about five or six hours. When
the magistral is well mixed, the quicksilver is applied, by being
sprinkled through pieces of coarse cloth doubled up like a bag, so that
it spurts out in very minute particles. The second treading of the
horses then follows; after which the whole mixture is turned over by six
men with wooden shovels, who perform the operation in an hour. The torta
is then smoothed and left at rest for one entire day, to allow the
incorporation to take place. It undergoes the turning by shovels and
treading by horses every other day, until the amalgamator ascertains
that the first admixture of quicksilver is found to be all taken up by
the silver; and this he does by vanning or washing a small quantity of
the torta in a little bowl. A new supply is then added, and when this
has done its duty, another is applied to catch any stray particles of
silver. On the same day, after a good repaso, the torta is removed on
hand-barrows by the labourers, to the _lavaderos_, in order that it may
receive its final cleansing. The general method of proportioning the
quicksilver to the tortas, is by allowing that every marco of silver
which is promised by trial of the ores as the probable produce of a
monton, will require in the whole process 4 lbs.

In metals of five to six marcs and a half per monton (of the average
richness of Zacatecas), 16 lbs. of quicksilver were incorporated for
every monton, = 900 lbs. for the torta. On the day of the second
addition, the proportion is 5 lbs. the monton; and when the torta is
ready to receive the last dose of quicksilver, it is applied at the rate
of 7 lbs. the monton, = 420 lbs.; making a total of 1620 lbs. of
quicksilver. With poorer ores, less quicksilver and less magistral are
required.

The usual time for the completion of the process of amalgamation, is
from 12 to 15 days in the summer, and 20 to 25 in the winter. This is
less than a third of the time taken at some other mines in Mexico. This
rapidity is owing to the tortas being spread very flat, and receiving
thereby the stronger influence of the sun. In the Mexican mines, only
one monton is commonly mixed at a time; and the lama is then piled in a
small conical heap or monton.

_Lavadero, or washing vat._--Here the prepared tortas are washed, in
order to carry off the earthy matters, and favour the deposition of the
amalgam at the bottom. Each vat is about 8 feet deep, and 9 in diameter;
and solidly built in masonry.

A large horizontal wheel, worked by mules, drives a vertical one, which
turns a horizontal wheel fitted round a perpendicular wooden shaft,
revolving upon an iron pivot at the bottom of the vat. To the lower end
of this shaft, four cross-beams are fitted, from which long wooden teeth
rise to the height of 5 feet. Their motion through the water being
rapid, keeps all the lighter particles afloat, while the heavier sink to
the bottom. The large wheel is worked by four mules, two at each
extremity of the cross-beam. Water is supplied from an elevated tank. It
requires 12 hours’ work of one tub to wash a torta. Eight porters are
employed in carrying the prepared _lama_ of the torta in hand-barrows to
the vats. The earthy matter receives a second washing.

[Illustration: 1005]

The amalgam is carried in bowls into the _azogueria_, where it is
subjected to straining through the strong canvas bottom of a leather
bag. The hard mass left in the bag is moulded into wedge-shaped masses
of 30 lbs., which are arranged in the burning-house, (_fig._ 1005.), to
the number of 11, upon a solid copper stand, called _baso_, having a
round hole in its centre. Over this row of wedges several others are
built; and the whole pile is called _pina_. Each circular range is
firmly bound round with a rope. The base is placed over a pipe which
leads to a small tank of water for condensing the quicksilver; a
cylindrical space being left in the middle of the _pina_, to give free
egress to the mercurial vapours.

A large bell-shaped cover, called _capellina_, is now hoisted up, and
carefully lowered over the _pina_, by means of pulleys. A strong lute of
ashes, saltierra, and lama is applied to its lower edge, and made to fit
very closely to the plate on which the base stands. A wall of
fire-bricks is then built loosely round the capellina, and this space is
filled with burning charcoal, which is thrice replenished, to keep it
burning all night. After the heat has been applied 20 hours, the bricks
and ashes are removed, the luting broken, and the capellina hoisted up.
The burned silver is then found in a hard mass, which is broken up,
weighed, and carried to the casting-house, to be formed into bars of
about 1080 ounces each. The loss of silver in burning, is about 5 ounces
to each bar (_barra_), and the loss of quicksilver, from 2-1/2 upon the
good metals, to 9 upon the coarse.

Molina told Mr. Miers, that the produce of the galena ores of Uspaltata
did not average more than 2 marcs per _caxon_ of 5000 lbs., which is an
excessively poor ore. The argentiferous galena ores of Cumberland afford
11 marcs per caxon; while the average produce of the Potosi silver ores
is only 5 or 6 marcs in the same quantity. These comparisons afford the
clearest evidence that the English mode of smelting can never be brought
into competition with the process of amalgamation as practised in
America.

Humboldt, Gay Lussac, Boussingault, Karsten, and several other chemists
of note, have offered solutions of the amalgamation enigma of Mexico and
Peru. The following seems to be the most probable _rationale_ of the
successive steps of the process:--

The addition of the _magistral_ (powder of the roasted copper pyrites),
is not for the purpose of disengaging muriatic acid from the sea salt
(_saltierra_), as has been supposed, since nothing of the kind actually
takes place; but, by reciprocal or compound affinity, it serves to form
chloride of copper, and chloride of iron, upon the one hand, and
sulphate of soda, upon the other. Were sulphuric acid to be used instead
of the magistral, as certain novices have prescribed, it would certainly
prove injurious, by causing muriatic acid to exhale. Since the ores
contain only at times oxide of silver, but always a great abundance of
oxide of iron, the acid would carry off both partly, but leave the
chloride of silver in a freer state. A magistral, such as sulphate of
iron, which is not in a condition to generate the chlorides, will not
suit the present purpose; only such metallic sulphates are useful as are
ready to be transformed into chlorides by the _saltierra_. This is
peculiarly the case with sulphate of copper. Its deuto-chloride gives up
chlorine to the silver, becomes in consequence a protochloride, while
the chloride of silver, thus formed, is revived, and amalgamated with
the quicksilver present, by electro-chemical agency which is excited by
the saline menstruum; just as the voltaic pile of copper and silver is
rendered active by a solution of sea salt. A portion of chloride of
mercury will be simultaneously formed, to be decomposed in its turn by
the sulphate of silver resulting from the mutual action of the acidified
pyrites, and the silver or its oxide in the ore. An addition of
quicklime counteracts the injurious effect of too much magistral, by
decomposing the resulting sulphate of copper. Quicksilver being an
excellent conductor of heat, when introduced in too great quantities, is
apt to cool the mass too much, and thereby enfeebles the operation of
the deuto-chloride of copper upon the silver.

There is a method of extracting silver from its ores by what is called
_imbibition_. This is exceedingly simple, consisting in depriving, as
far as possible, the silver of its gangue, then melting it with about
its own weight of lead. The alloy thus procured, contains from 30 to 35
_per cent._ of silver, which is separated by cupellation on the great
scale, as described under ores of LEAD. In this way the silver is
obtained at Kongsberg in Norway.

The amalgamation works at Halsbrücke, near Freyberg, for the treatment
of silver ores by mercury, have been justly admired as a model of
arrangement, convenience, and regularity; and I shall conclude this
subject with a sketch of their general distribution.

[Illustration: 1006]

_Fig._ 1006. presents a vertical section of this great _usine_ or
_hüttenwerk_, subdivided into four main departments. The first, A, B, is
devoted to the preparation and roasting of the matters intended for
amalgamation. The second, B, C, is occupied with two successive
siftings and the milling. The third, C, D, includes the amalgamation
apartment above, and the wash-house of the residuums below. And in the
fourth, D, E, the distilling apparatus is placed, where the amalgam is
finally delivered.

Thus, from one extremity of this building to the other, the workshops
follow in the order of the processes; and the whole, over a length of
180 feet, seems to be a natural laboratory, through which the materials
pass, as it were of themselves, from their crude to their refined
condition; so skilfully economized and methodical are the labours of the
workmen; such are the regularity, precision, concert, and facility,
which pervade this long series of combinations, carriages, movements,
and metamorphoses of matter.

Here we distinguish the following objects:--

1. In division A, B; _a_, _a_, is the magazine of salt; _b_, _b_, is the
hall of preparation of the ores; on the floor of which they are sorted,
interstratified, and mixed up with salt; _c_, _c_, are the roasting
furnaces; in each of which we see, 1, the fireplace; 2, 3, the
reverberatory hearth, divided into two portions, one a little higher
than the other, and more distant from the fireplace, called the _drier_.
The materials to be calcined fall into it, through a chimney 6. The
other part 2, of the hearth is the calcining area. Above the furnace are
chambers of sublimation 4, 5, for condensing some volatile matters which
escape by the opening 7. _e_ is the main chimney.

2. In the division B, C, we have _d_, the floor for the coarse sifting;
beneath, that for the fine sieves; from which the matters fall into the
hopper, whence they pass down to _g_, the mill-house, in which they are
ground to flour, exactly as in a corn-mill, and are afterwards boulted
through sieves, _p_, _f_, is the wheel machinery of the mill.

3. The compartment C, D, is the amalgamation work, properly speaking,
where the casks are seen in their places. The washing of the residuums
is effected in the shop _l_, below. _k_, _k_, is the compartment of
revolving casks.

4. In the division D, E, the distillation process is carried on. There
are four similar furnaces, represented in different states, for the sake
of illustration. The wooden drawer is seen below, supporting the
cast-iron basin, in which the tripod with its candelabra for bearing the
amalgam saucers is placed. _q_ is a store chamber.

At B, are placed the pulleys and windlass for raising the roasted ore,
to be sifted and ground; as also for raising the milled flour, to be
transported to the amalgamation casks. At D, the crane stands for
raising the iron bells that cover the amalgamation candelabra.

_Details of the Amalgamation Process, as practised at Halsbrücke._--All
ores which contain more than 7 lbs. of lead, or 1 lb. of copper, per
cent., are excluded from this reviving operation (_anquickverfahren_);
because the lead would render the amalgam very impure, and the copper
would be wasted. They are sorted for the amalgamation, in such a way
that the mixture of the poorer and richer ores may contain 7-1/2, or, at
most, 8 loths (of 1/2 oz. each) of silver per 100 lbs. The most usual
constituents of the ores are, sulphur, silver, antimonial silver
(speissglanzsilber), bismuth, sulphurets of arsenic, of copper, iron,
lead (nickel, cobalt), zinc, with several earthy minerals. It is
essential that the ores to be amalgamated shall contain a certain
proportion of sulphur, in order that they may decompose enough of sea
salt in the roasting to disengage as much chlorine as to convert all the
silver present into a chloride. With this view, ores poor in sulphur are
mixed with those that are richer, to make up a determinate average. The
ore-post is laid upon the _bed-floor_, in a rectangular heap, about 17
ells long, and 4-1/2 ells broad (13 yards and 3-1/2); and upon that
layer the requisite quantity of salt is let down from the floor above,
through a wooden tunnel; 40 cwts. of salt being allotted to 400 cwts. of
ore. The heap being made up with alternate strata to the desired
magnitude, must be then well mixed, and formed into small bings, called
_roast-posts_, weighing each from 3-1/2 to 4-1/2 cwts. The annual
consumption of salt at Halsbrücke is 6000 cwts.; it is supplied by the
Prussian salt-works.

_Roasting of the Amalgamation Ores._--The furnaces appropriated to the
roasting of the ore-posts are of the reverberatory class, provided with
soot chambers. They are built up alongside of the _bed-floor_, and
connected with it by a brick tunnel. The prepared ground ore (_erzmehl_)
is spread out upon the hearth, and dried with incessant turning over;
then the fire is raised so as to kindle the sulphur, and keep the ore
redhot for one or two hours; during which time, dense white-gray vapours
of arsenic, antimony, and water, are exhaled. The desulphuration next
begins, with the appearance of a blue flame. This continues for three
hours, during which the ignition is kept up; and the mass is diligently
turned over, in order to present new surfaces, and to prevent any
caking. Whenever sulphurous acid ceases to be formed, the finishing
calcination is to be commenced with increased firing; the object being
now to decompose the sea salt by means of the metallic sulphates that
have been generated, to convert them into chlorides, with the
simultaneous production of sulphate of soda. The stirring is to be
continued till the proofs taken from the hearth no longer betray the
smell of sulphurous, but only of muriatic acid gas. This roasting stage
lasts commonly three quarters of an hour, 13 or 14 furnaces are worked
at the same time at Halsbrücke; and each turns out in a week 5 tons
upon an average. Out of the _nicht_ chambers or soot vaults of the
furnaces, from 96 to 100 cwts. of ore-dust are obtained, containing 32
marcs (16 lbs.) of silver. This dust is to be treated like unroasted
ore. The fuel of the first fire is pitcoal; of the finishing one,
fir-wood. Of the former 115-1/2 cubic feet, and of the latter, 294-1/4,
are, upon an average, consumed for every 100 cwts. of ore.

During the last roasting, the ore increases in bulk by one fourth,
becomes in consequence a lighter powder, and of a brown colour. When
this process is completed, the ore is raked out upon the stone pavement,
allowed to cool, then screened in close sieve-boxes, in order to
separate the finer powder from the lumps. These are to be bruised, mixed
with sea salt, and subjected to another calcination. The finer powder
alone is taken to the millstones, of which there are 14 pairs in the
establishment. The stones are of granite, and make from 100 to 120
revolutions per minute. The roasted ore, after it has passed through the
boulter of the mill, must be as impalpable as the finest flour.

_The Amalgamation._--This (the _verquicken_) is performed in 20
horizontal casks, arranged in 4 rows, each turning upon a shaft which
passes through its axis; and all driven by the water-wheel shown in the
middle of _fig._ 1006. The casks are 2 feet 10 inches long, 2 feet 8
inches wide, inside measure, and are provided with iron ends. The staves
are 3-1/2 inches thick, and are bound together with iron hoops. They
have a double bung-hole, one formed within the other, secured by an iron
plug fastened with screws. They are filled by means of a wooden spout
terminated by a canvas hose; through which 10 cwts. of the boulted
ore-flour (_erzmehl_) are introduced after 3 cwts. of water have been
poured in. To this mixture, from 3/4 to 7/8 of a cwt. of pieces of iron,
1-1/2 inch square, and 3/8 thick, are added. When these pieces get
dissolved, they are replaced by others from time to time. The casks
being two thirds full, are set to revolve for 1-1/2 or 2 hours, till the
ore-powder and water become a uniform pap; when 5 cwts. of quicksilver
are poured into each of them. The casks being again made tight, are put
in geer with the driving machinery, and kept constantly revolving for 14
or 16 hours, at the rate of 20 or 22 turns in the minute. During this
time they are twice stopped and opened, in order to see whether the pap
be of the proper consistence; for if too thick, the globules of
quicksilver do not readily combine with the particles of ore; and if too
thin, they fall and rest at the bottom. In the first case, some water
must be added; in the second, some ore. During the rotation, the
temperature rises, so that even in winter it sometimes stands so high as
104° F.

The chemical changes which occur in the casks are the following:--The
metallic chlorides present in the roasted ore are decomposed by the
iron, whence results muriate of iron, whilst the deutochloride of copper
is reduced partly to protochloride, and partly to metallic copper, which
throw down metallic silver. The mercury dissolves the silver, copper,
lead, antimony, into a complex amalgam. If the iron is not present in
sufficient quantity, or if it has not been worked with the ore long
enough to convert the copper deutochloride into a protochloride,
previously to the addition of the mercury, more or less of the last
metal will be wasted by its conversion into protochloride (calomel). The
water holds in solution sulphate of soda, undecomposed sea salt, with
chlorides of iron, manganese, &c.

As soon as the revivification is complete, the casks must be filled with
water, set to revolve slowly (about 6 or 8 times in the minute), whereby
in the course of an hour, or an hour and a half at most, a great part of
the amalgam will have collected at the bottom; and in consequence of the
dilution, the portion of horn silver held in solution by the sea salt
will fall down and be decomposed. Into the small plug in the centre of
the bung, a small tube with a stopcock is now to be inserted, to
discharge the amalgam into its appropriate chamber. The cock must be
stopped whenever the brown muddy residuum begins to flow. The main bung
being then opened, the remaining contents of the casks are emptied into
the _wash-tun_, while the pieces of iron are kept back. The residuary
ore is found to be stripped of its silver within 5/32 or 7/40 of an
ounce per cwt. The emptying of all the casks, and charging them again,
takes 2 hours; and the whole process is finished within 18 or 20 hours;
namely, 1 hour for charging, 14 to 16 hours for amalgamating; 1-1/2 hour
for diluting; 1 hour for emptying. In 14 days, 3200 cwts. of ore are
amalgamated. For working 100 cwts. of ore, 14-1/2 lbs. of iron, and 2
lbs. 12-1/2 ounces of mercury, are required; whence, for every pound of
silver obtained, 0·95 of an ounce of mercury are consumed.

Trials have been made to conduct the amalgamation process in iron casks,
heated to 150° or 160° Fahrenheit, over a fire; but though the
de-silvering was more complete, the loss by mercury was so much greater
as to more than counterbalance that advantage.

_Treatment of the Amalgam._--It is first received in a moist canvas bag,
through which the thin uncombined quicksilver spontaneously passes. The
bag is then tied up and subjected to pressure. Out of 20 casks, from 3
to 3-1/2 cwts. of solid amalgam are thus procured, which usually consist
of 1 part of an alloy, containing silver of 12 or 13 _loths_ (in 16),
and 6 parts of quicksilver. The foreign metals in that alloy are,
copper, lead, gold, antimony, cobalt, nickel, bismuth, zinc, arsenic,
and iron. The filtered quicksilver contains moreover 2 to 3 loths of
silver in the cwt.

[Illustration: 1007]

_Fig._ 1007. represents the apparatus for distilling the amalgam in the
Halsbrücke works, marked _m_ in _fig._ 1006. _a_ is the wooden drawer,
sliding in grooves upon the basis _q_; B is an open basin or box of cast
iron, laid in the wooden drawer; _y_ is a kind of iron candelabra,
supported upon four feet, and set in the basin B; under _d_ are five
dishes or plates, of wrought iron, with a hole in the centre of each,
whereby they are fitted upon the stem of the candelabra, 3 inches apart,
each plate being successively smaller than the one below it. 3 indicates
a cast-iron bell, furnished with a wrought-iron frame and hook, for
raising it by means of a pulley and cord. _s_ is a sheet-iron door for
closing the stove, whenever the bell has been set in its place.

The box _a_, and the basin B, above it, are filled with water, which
must be continually renewed, through a pipe in the side of the wooden
box, so that the iron basin may be kept always submersed and cool. The
drawer _a_, being properly placed, and the plates under _d_ being
charged with balls of amalgam (weighing altogether 3 cwts.), the bell 3
is to be let down into the water, as at _y_, and rested upon the lower
part of the candelabra. Upon the ledge 1, which defines the bottom of
the fireplace, a circular plate of iron is laid, having a hole in its
middle for the bell to pass through. Upon this plate chips of fir-wood
are kindled, then the door _s_, which is lined with clay, is closed and
luted tight. The fuel is now placed in the vacant space _k_, round the
upper part of the bell. The fire must be fed in most gradually, first
with turf, then with charcoal; whenever the bell gets red, the mercury
volatilizes, and condenses in globules into the bottom of the basin B.
At the end of 8 hours, should no more drops of mercury be heard to fall
into the water, the fire is stopped. When the bell has become cool, it
is lifted off; the plates are removed from the candelabra _d_; and this
being taken out, the drawer _a_ is slid away from the furnace. The
mercury is drained, dried, and sent again into the amalgamation works.
The silver is fused and refined by cupellation.

The solid amalgam which is distilled in the above apparatus, would be
distilled more profitably out of iron trays set in the mercurial retorts
described and figured in pages 809, 810.

From 3 cwts. of amalgam, distilled under the bell, from 95 to 100 marcs
(1/2 lbs.) of _teller_ silver (dish silver) are procured, containing
from 10 to 13-1/2 parts of fine silver out of 16; one-fifth part of the
metal being copper. The _teller_ silver is refined in quantities of 160
or 170 marcs, in black-lead crucibles filled within two inches of their
brims, and submitted to brisk ignition. The molten mass exhales some
vapours, and throws up a liquid slag, which being skimmed off, the
surface is to be strewed over with charcoal powder, and covered with a
lid. The heat having been briskly urged for a short time, the charcoal
is then removed along with any fresh slag that may have risen, in order
to observe whether the vapours have ceased. If not, fresh charcoal must
be again applied, the crucible must be covered, and the heat increased,
till fumes are no longer produced, and the surface of the silver becomes
tranquil. Finally, the alloy, which contains a little gold, and much
copper, being now from 11 to 13 _löthig_ (that is, holding from 11 to 13
parts of fine silver in 16 parts), is cast into iron moulds, in ingots
of 60 marcs. The loss of weight by evaporation and skimming of the slag
amounts to 2 per cent.; the loss in silver is quite inconsiderable.

The dust from the furnace (_tiegelöfen_) is collected in a large
condensation chamber of the chimney, and affords from 40 to 50 marcs of
silver per cwt. The slags and old crucibles are ground and sent to the
small amalgamation mill.

The earthy residuum of the amalgamation casks being submitted to a
second amalgamation, affords out of 100 cwts. about 2 lbs. of coarse
silver. This is first fused along with three or four per cent. of a
mixture of potashes and calcined quicksalz, (impure sulphate of soda),
and then refined. The supernatant liquor that is drawn out of the tanks
in which the contents of the casks are allowed to settle, consists
chiefly of sulphate of soda, along with some common salt, sulphates of
iron and manganese, and a little phosphate, arseniate, and fluate of
soda. The earthy deposit contains from 1/4 to 9/32 of a _loth_ of silver
per cwt., but no economical method of extracting this small quantity has
yet been contrived.

[Illustration: 1008 1009 1010 1011]

The argentiferous or _rich lead_ is treated in Germany by the
cupellation furnace represented in _figs._ 1008, 1009, 1010, and 1011.
These figures exhibit the cupellation furnace of the principal smelting
work in the Hartz, where the following parts must be distinguished;
(_fig._ 1010.) 1, masonry of the foundation; 2, flues for the escape of
moisture; 3, stone covers of the flues; 4, bed of hard rammed scoriæ; 5,
bricks set on edge, to form the permanent area of the furnace; 6, the
sole, formed of wood ashes, washed, dried, and beaten down; _k_, dome of
iron plate, movable by a crane, and susceptible of being lined two
inches thick with loam; _n_, _n_, tuyères for two bellows _s_; having
valves suspended before their orifices to break and spread the blast;
_q_, door for introducing into the furnace the charge of lead, equal to
84 quintals at a time; _s_, _fig._ 1011., two bellows, like those of a
smith’s forge; _y_, door of the fireplace, through which billets of wood
are thrown on the grate; _x_, small aperture or door, for giving issue
to the frothy scum of the cupellation, and the litharge; _z_, basin of
safety, usually covered with a stone slab, over which the litharge
falls: in case of accident the basin is laid open to admit the _rich
lead_.

The following is the mode of conducting the cupellation. Before putting
the lead into the furnace, a floor is made in it of ashes beat carefully
down (see 6, _fig._ 1010.); and there is left in the centre of this
floor a circular space, somewhat lower than the rest of the hearth,
where the silver ought to gather at the end of the operation. The cupel
is fully six feet in diameter.

In forming the floor of a cupel, 35 cubic feet of washed wood ashes,
usually got from the soap works, are employed. The preparation of the
floor requires 2-1/2 hours’ work; and when it is completed, and the
movable dome of iron plate has been lined with loam, 84 quintals (cwt.)
of lead are laid on the floor, 42 quintals being placed in the part of
the furnace farthest from the bellows, and 42 near to the fire-bridge;
to these, scoriæ containing lead and silver are added, in order to lose
nothing. The movable lid is now luted on the furnace, and heat is slowly
applied in the fireplace, by burning fagots of fir-wood, which is
gradually raised. Section 1010. is in the line C, D, of 1009.

At the end of three hours, the whole lead being melted, the instant is
watched for when no more ebullition can be perceived on the surface of
the bath or melted metal; then, but not sooner, the bellows are set
a-playing on the surface at the rate of 4 or 5 strokes per minute, to
favour the oxidizement.

In five hours, reckoned from the commencement of the process, the fire
is smartly raised; when a grayish froth (_abstrich_) is made to issue
from the small aperture _x_ of the furnace. This is found to be a
brittle mixture of oxidized metals and impurities. The workman now
glides the rake over the surface of the bath, so as to draw the froth
out of the furnace; and, as it issues, powdered charcoal is strewed upon
it, at the aperture _x_, to cause its coagulation. The froth skimming
lasts for about an hour and a half.

After this time, the litharge begins to form, and it is also let off by
the small opening _x_; its issue being aided by a hook. In proportion as
the floor of the furnace gets impregnated with litharge, the workman
digs in it a gutter for the escape of the liquid litharge: it falls in
front of the small aperture, and concretes in stalactitic forms.

By means of the two movable valves suspended before the tuyères _n_,
_n_, (_fig._ 1010.) the workman can direct the blast as he will over the
surface of the metal. The wind should be made to cause a slight curl on
the liquid, so as to produce circular undulations, and gradually propel
a portion of the litharge generated, towards the edges of the cupel, and
allow this to retain its shape till the end of the operation. The stream
of air should drive the greater part of the litharge towards the small
opening _x_, where the workman deepens the outlet for it, in proportion
as the level of the metal bath descends, and the bottom of the floor
rises by the apposition of the litharge formed. Litharge is thus
obtained during about 12 hours; after which period the cake of silver
begins to take shape in the centre of the cupel.

Towards the end of the operation, when no more than four additional
quintals of litharge can be looked for, and when it forms solely in the
neighbourhood of the silver cake in the middle of the floor, great care
must be taken to set apart the latter portions, because they contain
silver. About this period, the fire is increased, and the workman places
before the little opening _x_ a brick, to serve as a mound to the efflux
of litharge. The use of this brick is,--1, to hinder the escape of the
silver in case of any accident; for example, should an explosion take
place in the furnace; 2, to reserve a magazine of litharge, should that
still circulating round the silver cake be suddenly absorbed by the
cupel, for in this dilemma the litharge must be raked back on the
silver; 3, to prevent the escape of the water that must be thrown on the
silver at the end of the process.

When the argentiferous litharge, collected in the above small magazine,
is to be removed, it is let out in the form of a jet, by the dexterous
use of the iron hook.

Lastly, after 20 hours, the silver cake is seen to be well formed, and
nearly circular. The moment for stopping the fire and the bellows is
indicated by the sudden disappearance of the coloured particles of oxide
of lead, which, in the latter moments of oxidation, undulate with
extreme rapidity over the slightly convex surface of the silver bath,
moving from the centre to the circumference. The phenomenon of their
total disappearance is called the _lightning_, or fulguration. Whenever
this occurs, the plate of silver being perfectly clean, there is
introduced into the furnace, by the door _q_, a wooden spout, along
which water, previously heated, is carefully poured on the silver.

The cupellation of 84 quintals of argentiferous lead takes in general 18
or 20 hours’ working. The promptitude of the operation depends on the
degree of purity of the leads employed, and on the address of the
operator, with whom also lies the economy of fuel. A good workman
completes the cupellation of 84 quintals with 300 billets, each
equivalent to a cubic foot and eight-tenths of wood (Hartz measure);
others consume 400 billets, or more. In general, the cupellation of 100
quintals of lead, executed at the rate of 84 quintal charges, occasions
a consumption of 790 cubic feet of resinous wood billets.

The products of the charge are as follow:--

  1. Silver, holding in 100 marcs, 7 marcs and 3
     loths of alloy                                  24 to 30 marcs.
  2. Pure litharge, containing from 88 to 90 per
     cent. of lead                                   50  - 60 quintals.
  3. Impure litharge, holding a little silver         2  -  6    --
  4. Skimmings of the cupellation                     4  -  8    --
  5. Floor of the furnace impregnated with litharge  22  - 30    --

NOTE.--_The marc is 7 oz. 2 dwts. 4 gr. English troy; and the loth is
half an ounce. 16 loths make a marc. 100 pounds Cologne are equal to 103
pounds avoirdupois; and the above quintal contains 116 Cologne pounds._

The loss of lead inevitable by this operation, is estimated at 4 parts
in 100. It has been diminished as much as possible in the Frankenscharn
works of the Hartz, by leading the smoke into long flues, where the lead
fumes are condensed into a metallic soot. The silver cake receives a
final purification at the Mint, in a cupel on a smaller scale.

From numerous experiments in the great way, it has been found that not
more than 100 quintals of lead can be profitably cupelled at one
operation, however large the furnace, and however powerful and
multiplied the bellows and tuyères may be; for the loss on either the
lead or the silver, or on both, would be increased. In one attempt, no
less than 500 quintals were acted on, in a furnace with two fireplaces,
and four escapes for the litharge; but the silver remained disseminated
through the lead, and the _lightning_ could not be brought on. The chief
object in view was economy of fuel.

_Reduction of the Litharge._--This is executed in a slag-hearth, with
the aid of wood charcoal.

Such is the train of operations by which the cupriferous galena
_schlich_, or ground ore is reduced, in the district of Clausthal, into
lead, copper, and silver. The works of Frankenscharn have a front fully
400 feet long.

[Illustration: 1012 _Silver-smelting Works of Frankenscharn, near
Clausthal._]

_Fig._ 1012. exhibits the plan and elevation of these smelting-works,
near Clausthal, in the Hartz, for lead ores containing copper and
silver, where about 84,000 cwts. of _schlich_ (each of 123 Cologne
pounds) are treated every year. This quantity is the produce of 30
distinct mines, as also of nearly as many stamp and preparation works.
All these different _schlichs_, which belong to so many different
joint-stock companies, are confounded and worked up together in the same
series of metallurgic operations; the resulting mixture being considered
as one and the same ore belonging to a single undertaking; but in virtue
of the order which prevails in this royal establishment, the rights of
each of the companies, and consequently of each shareholder, are
equitably regulated. A vigorous control is exercised between the mines
and the stamps, as also between the stamps and the smelting-houses;
while the cost of the metallurgic operations is placed under the
officers of the crown, and distributed, upon just principles, among the
several mines, according to the quantities of metal furnished by each.

From these arrangements, the following important advantages flow:--

1. The poor ores may be smelted with profit, without putting the
companies to any risk or expense in the erection of new works; 2, by the
mixture of many different ores, the smelting and metallic product become
more easy and abundant; 3, the train of the operations is conducted with
all the lights and resources of science; and 4, the amount of metal
brought into the market is not subject to such fluctuations as might
prove injurious to their sale.

The following is the series of operations:--

1, The fusion of the schlich (sludge); 2, the roasting of the mattes
under a shed, and their treatment by four successive re-meltings; 3, the
treatment of the resulting black copper; 4, the liquation; 5, the
reliquation (_ressuage_); 6, the refining of the copper; 7, the
cupellation of the silver; 8, the reduction of the litharge into lead.
The 5th and 6th processes are carried on at the smelting works of
Altenau.

The buildings are shown at A, B, C, and the impelling stream of water at
D; the upper figure being the elevation; the lower, the plan of the
works.

[Illustration: 1013]

_a_, is the melting furnace, with a cylinder bellows behind it; _b_,
_c_, _d_, furnaces similar to the preceding, with wooden bellows, such
as _fig._ 1013; _e_, is a furnace for the same purpose, with three
tuyères, and a cylinder bellows; _f_, the large furnace of fusion, also
with three tuyères; _g_, a furnace with seven tuyères, now seldom used;
_h_, low furnaces, like the English slag-hearths (_krummofen_), employed
for working the last _mattes_; _k_, slag-hearths for reducing the
litharge; _m_, the area of the liquation; _n_, _p_, cupellation
furnaces.

_x_, _y_, a floor which separates the principal smelting-house into two
stories; the materials destined for charging the furnaces being
deposited in beds upon the upper floor, to which they are carried by
means of two inclined planes, terraced in front of the range of
buildings.

Here 89,600 quintals of schlich are annually smelted, which furnish--

  Marketable lead                                       20,907 quintals.
  Marketable litharge, containing 90 per cent. of lead   7,555
  Silver, about                                             67
  Copper (finally purified in the works of Altenau)         35
                                                        ------
  Total product                                         28,564

This weight amounts to one twenty-fifth of the weight of ore raised for
the service of the establishment. Eight parts of ore furnish, on an
average, about one of schlich. The bellows are constructed wholly of
wood, without any leather; an improvement made by a bishop of Bamberg,
about the year 1620. After receiving different modifications, they were
adopted, towards 1730, in almost all the smelting-works of the
continent, except in a few places, as Carniola, where local
circumstances permitted a water blowing-machine to be erected. These
pyramidal shaped bellows, composed of movable wooden boxes, have,
however, many imperfections: their size must often be inconveniently
large, in order to furnish an adequate stream of air; they do not drive
into the furnace all the air which they contain; they require frequent
repairs; and, working with great friction, they waste much mechanical
power.

[Illustration: 1014]

_Fig._ 1014. represents such wooden bellows, consisting of two chests or
boxes, fitted into each other; the upper or moving one being called the
_fly_, the lower or fixed one, the _seat_ (_gite_). In the bottom of the
_gite_, there is an orifice furnished with a clack-valve _d_, opening
inwards when the _fly_ is raised, and shutting when it falls. In order
that the air included in the capacity of the two chests may have no
other outlet than the nose-pipe _m_, the upper portion of the _gite_ is
provided at its four sides with small square slips of wood _c_, _c_,
_c_, which are pressed against the sides of the _fly_ by strong springs
of iron wire _b_, _b_, _b_, while they are retained upon the _gite_ by
means of small square pieces of wood _a_, _a_, _a_, _a_. The latter _a_,
_a_, are perforated in the centre, and adjusted upon rectangular stems,
called _buchettes_; they are attached, at their lower ends, to the
upright sides of the _gite_ G. P is the driving-shaft of a water-wheel,
which, by means of cams or tappets, depresses the fly, while the
counterweight Q, _fig._ 1013., raises it again.

_Figs._ 1015, 1016, 1017, 1018. represent the moderately high
(_demihauts_, or _half-blast_,) furnaces employed in the works of the
lower Hartz, near Goslar, for smelting the silvery lead ores extracted
from the mine of Rammelsberg. See its section, in _fig._ 737.

[Illustration: 1015 1016]

_Fig._ 1015. is the front elevation of the twin furnaces, built in one
body of masonry; _fig._ 1016. is a plan taken at the level of the
tuyères, in the line _v_, _l_, 6. of _fig._ 1017.; _figs._ 1017. and
1018. exhibit two vertical sections; the former in the line A, B, the
latter in the line C, D, of _fig._ 1016. In these four figures the
following objects may be distinguished.

_a_, _b_, _c_, _d_, a balcony or platform, which leads to the place of
charging _n_; _e_, _f_, wooden stairs, by which the charging workmen
mount from the ground _p_, _q_, of the works, to the platform; _g_, _h_,
brickwork of the furnaces; _i_, _k_, wall of the smelting-works, against
which they are supported; _l_, upper basin of reception, hollowed out of
the _brasque_ (or ground charcoal bed) 6; _m_, arch of the tuyère _v_,
by which each furnace receives the blast of two bellows; _n_, place of
charging, which takes place through the upper orifice _n_, _o_, of the
basin _n_, _o_, _v_, _t_, of the furnace; _t_, a slab of clay, placed in
such a way that, during the treatment of the lead, a little metallic
zinc may run together in a sloping gutter, seen in _fig._ 1001., formed
of slates cemented together with clay.

[Illustration: 1017]

In _figs._ 1015 and 1017., _l_, _z_, is the brickwork of the
foundations; _m_, conduits (called evaporatory), for the exhalation of
the moisture; 4, a layer of slags, rammed above; 5, a bed of clay,
rammed above the slags; 6, a brasque, composed of one part of clay, and
two parts of ground charcoal, which forms the sole of the furnace.

[Illustration: 1018 1019 1020]

The excellent refinery furnace, or _treibheerd_, of Frederickshütte,
near Tarnowitz, in Upper Silesia, is represented in _figs._ 1019. and
1020. _a_, is the bottom, made of slag or cinders; _b_, the foundation,
of fire-bricks; _c_, the body of the hearth proper, composed of a
mixture of 7 parts of dolomite, and 1 of fire-clay, in bulk; _d_, the
grate of the air furnace; _e_, the fire-bridge; _f_, the dome or cap,
made of iron plate strengthened with bars, and lined with clay-lute, to
protect the metal from burning; _g_, the door of the fireplace; _h_, the
ash-pit; _i_, the tap-hole; _k_, _k_, the flue, which is divided by
partitions into several channels; _l_, the chimney; _m_, a damper-plate
for regulating the draught; _n_, a back valve, for admitting air to cool
the furnace, and brushes to sweep the flues; _o_, _tuyère_ of copper,
which by means of an iron wedge may be sloped more or less towards the
hearth; _p_, the _schnepper_, a round piece of sheet iron, hung before
the _eye_ of the _tuyère_, to break and spread the blast; _q_, the
outlet for the glassy litharge.

Lime-marl has been found to answer well for making the body of the
hearth-sole, as it absorbs the vitrified litharge freely, without
combining with it. A basin-shaped hollow is formed in the centre, for
receiving the silver at the end of the process; and a gutter is made
across the hearth for running off the _glätte_ or fluid litharge.

[Illustration: 1021 1022 1023]

_Figs._ 1021, 1022. represent the eliquation hearth of Neustadt. _Fig._
1021. is a cross section; _fig._ 1022. is a front view; and _fig._ 1023.
a longitudinal section. It is formed by two walls _a_, _a_, 3-1/2 feet
high, placed from 1/2 to 1 foot apart, sloped off at top with iron
plates, 3 inches thick, and 18 inches broad, called _saigerscharten_, or
refining plates, _b_, _b_, inclined 3 inches towards each other in the
middle, so as to leave at the lowest point a slit 2-1/2 inches wide
between them, through which the lead, as it sweats out by the heat, is
allowed to fall into the space between the two walls _c_, called the
_saigergasse_ (sweating-gutter). The sole of this channel slopes down
towards the front, so that the liquefied metal may run off into a
crucible or pot. Upon one of the long sides, and each of the shorter
ones, of the hearth, the walls _d_, _d_, are raised two feet high, and
upon these the liquation lumps rest; upon the other long side, where
there is no wall, there is an opening for admitting these lumps into the
hearth. The openings are then shut with a sheet or cast iron plate _e_,
which, by means of a chain, pulley, and counterweight, may be easily
raised and lowered. _f_, is a passage for increasing the draught of air.

[Illustration: 1024 1025]

_Figs._ 1024. and 1025. represent the refining furnaces of
Frederickshütte by Tarnowitz; _a_, is the fire-door; _b_, the grate;
_c_, the door for introducing the silver; _d_, the movable test, resting
upon a couple of iron rods _e_, _e_, which are let at their ends into
the brickwork. They lie lower than would seem to be necessary; but this
is done in order to be able to place the surface of the test at any
desired level, by placing tiles _f_, _f_, under it; _g_, the flue,
leading to a chimney 18 feet high. For the refining of 100 marks of
_blicksilber_, of the fineness of 15-1/2 loths (half ounces) per cwt., 3
cubic feet of pitcoal are required. The test or cupel must be heated
before the impure silver and soft lead are put into it.

At these smelting-houses from 150 to 160 cwt. of very pure _workable
lead_ (lead containing merely a little silver) are put into the furnace
at once, and from 10 to 14 cwt. run off in vitrified oxide; the
remainder is then refined with some pure lead, when an alloy containing
from 14-1/2 to 15-1/2 loths of blicksilber per cwt. is obtained.

[Illustration: 1026 1027]

_English refining furnaces._--The refining of lead is well performed in
some works in the neighbourhood of Alston-moor, in reverberatory
furnaces, _figs._ 1026. and 1027., whose fireplace is 22 inches square,
and is separated from the sole by a fire-bridge, 14 inches in breadth.
The flame, after having passed over the surface of the lead in the
cupel, enters two flues _e_, _e_, on the opposite side of the furnace,
which terminate in a chimney _i_, _i_, _i_, _i_, 40 feet high. At the
bottom of the chimney are openings _f_, _f_, for taking out the metallic
dust deposited within. These openings are shut during the process.

[Illustration: 1028 1029]

The cupel or test, which constitutes, in fact, the sole of the hearth in
which the operation takes place, is movable. It consists of a vertical
elliptical ring of iron, A, B, C, D, _figs._ 1028. and 1029., 3-3/4
inches high, the greatest diameter of the ellipse being 4 feet, and the
smallest 2-1/2. Four iron bars (A D, _m_, _m´_, B C, _n_, _n´_,) are
fixed across its bottom, which are also 3-3/4 inches broad, and an inch
thick. The first of these bars is placed 9 inches from the end of the
elliptic ring nearest the fireplace, and the three others are equally
distributed between this bar and the back end.

In forming the cupel, several layers of a mixture of moistened bone
ashes, and fern ashes, in very fine powder, are put into the
_test-frame_. The bone ash constitutes from 1/8 to 1/16 of the bulk of
the mixture, according to the purity of the fern ashes employed,
estimated by the proportion of potash they contain, which has the
property of semi-vitrifying the powder of burnt bones, of thus removing
its friability, and rendering it more durable. The layers of ashes are
strongly beat down, till the frame is entirely filled. The mass thus
formed is then hollowed out by means of a little spade, made on purpose,
till it is only three quarters of an inch thick above the iron bars near
the centre of the bottom. A flange, 2 inches broad, is made at the upper
part, and 2-1/2 inches at the lower part, except on the front or
_breast_, which is 5 inches thick. In this anterior part, there is
hollowed out an opening of an inch and a quarter broad, and 6 inches
long, with which the outlet or _gateway_ of the litharge communicates.

The cupel thus prepared is placed in the refining furnace. It rests in
an iron ring built into the brickwork. The arched roof of the furnace is
12 inches above the cupel near the fire-bridge, and 9 inches near the
flue at the other end.

The tuyère is placed in the back of the furnace, opposite to the side at
which the litharge is allowed to overflow.

Openings _g_, _g_, are left at the sides of each cupel, either for
running off or for introducing melted lead.

_Refining of lead to extract its silver._--This operation, which the
lead of Derbyshire cannot be submitted to with advantage, is performed
in a certain number of the smelting-houses at Alston-moor, and always
upon leads reduced in the Scotch furnace.

The cupel furnace above described, must be slowly heated, in order to
dry the cupel without causing it to crack, which would infallibly be
produced by sudden evaporation of the moisture in it. When it has been
thus slowly brought to the verge of a red heat, it is almost completely
filled with lead previously melted in an iron pot. The cupel may be
charged with about 5 cwt. At the temperature at which the lead is
introduced, it is immediately covered with a gray pellicle of oxide; but
when the heat of the furnace has been progressively raised to the proper
pitch, it becomes whitish-red, and has its surface covered over with
litharge. Now is the time to set in action the blowing-machine, the
blast of which, impelled in the direction of the great axis of the
cupel, drives the litharge towards the _breast_ of the cupel, and makes
it flow out by the _gateway_ prepared for it, through which it falls
upon a cast-iron plate, on a level with the floor of the apartment, and
is dispersed into tears. It is carried in this state to the furnace of
reduction, and revived. As by the effect of the continual oxidization
which it undergoes, the surface of the metal necessarily falls below the
level of the gateway of the litharge, melted lead must be added anew by
ladling it into the furnace from the iron boiler, as occasion may
require. The operation is carried on in this manner till 84 cwt. or 4
Newcastle _fodders_ of lead have been introduced, which takes from 16 to
18 hours, if the tuyère has been properly set. The whole quantity of
silver which this mass of lead contains, is left in combination with
about 1 cwt. of lead, which, under the name of rich lead, is taken out
of the cupel.

When a sufficient number of these pieces of rich lead have been
procured, so that by their respective quality, as determined by
assaying, they contain in whole from 1000 to 2000 ounces of silver, they
are re-melted to extract their silver, in the same furnace, but in a
cupel which differs from the former in having at its bottom a depression
capable of receiving at the end of the process the cake of silver. In
this case a portion of the bottom remains uncovered, on which the scoriæ
may be pushed aside with a little rake, from the edges of the silver.

The experiments of MM. Lucas and Gay Lussac have proved that fine
silver, exposed to the air in a state of fusion, absorbs oxygen gas, and
gives it out again in the act of consolidation. The quantity of oxygen
thus absorbed may amount to twenty-two times the volume of the silver.
The following phenomena are observed when the mass of metal is
considerable; for example, from 40 to 50 pounds.

The solidification commences at the edges, and advances towards the
centre. The liquid silver, at the moment of its passage to the solid
state, experiences a slight agitation, and then becomes motionless. The
surface, after remaining thus tranquil for a little, gets all at once
irregularly perturbed, fissures appear in one or several lines, from
which flow, in different directions, streams of very fluid silver, which
increase the original agitation. The first stage does not yet clearly
manifest the presence of gas, and seems to arise from some intestine
motion of the particles in their tendency to group, on entering upon the
process of crystallization, and thus causing the rupture of the envelop
or external crust, and the ejection of some liquid portions.

After remaining some time tranquil, the metal presents a fresh
appearance, precisely analogous to volcanic phenomena. As the
crystallization continues, the oxygen gas is given out with violence at
one or more points, carrying with it melted silver from the interior of
the surface, producing a series of cones, generally surmounted by a
small crater, vomiting out streams of the metal, which may be seen
boiling violently within them.

These cones gradually increase in height by the accumulation of metal
thrown up, and that which becomes consolidated on their sloping sides.
The thin crust of metal on which they rest, consequently experiences
violent impulses, being alternately raised and depressed by such violent
agitation, that were it not for the tenacity and elasticity of the
metal, there would evidently arise dislocation, fissures, and other
analogous accidents. At length several of the craters permanently close,
while others continue to allow the gas a passage. The more difficult
this is, the more the craters become elevated, and the more their
funnels contract by the adhesion or coagulation of a portion of the
metal. The projection of globules of silver now becomes more violent;
the latter being carried to great distances, even beyond the furnace,
and accompanied by a series of explosions, repeated at short intervals.
It is generally the last of these little volcanoes that attains the
greatest altitude, and exhibits the foregoing phenomena with the
greatest energy. It is, moreover, observable, that these cones do not
all arise at the same time, some having spent their force, when others
commence forming at other points. Some reach the height of an inch,
forming bases of two or three inches in diameter. The time occupied by
this exhibition is at least from half to three quarters of an hour.

During the formation of these cones, by the evolution of gas, portions
of silver are shot forth, which assume, on induration, a form somewhat
cylindrical, and often very fantastic, notwithstanding the
incompatibility which appears to exist between the fluidity of the
silver and these elongated figures. Their appearance is momentary, and
without any symptoms of gas, although it is impossible to decide whether
they may not arise from its influence; they seem, in fact, to resemble
the phenomena of the first volcanic period.

Till very recently the only operations employed for separating silver
from lead in the English smelting-works, were the following:--

1. Cupellation, in which the lead was converted into a vitreous oxide,
which was floated off from the surface of the silver.

2. Reduction of that oxide, commonly called litharge.

3. Smelting the bottoms of the cupels, to extract the lead which had
soaked into them, in a glassy state.

Cupellation and its two complementary operations were, in many respects,
objectionable processes; from the injurious effects of the lead vapours
upon the health of the workmen; from the very considerable loss of
metallic lead, amounting to 7 per cent. at least; and, lastly, from the
immense consumption of fuel, as well as from the vast amount of manual
labour incurred in such complicated operations. Hence, unless the lead
were tolerably rich in silver, it would not bear the expense of
cupellation.

The patent process lately introduced by Mr. Pattinson, of Newcastle, is
not at all prejudicial to the health of workmen; it does not occasion
more than 2 per cent. of loss of lead, and in other respects it is so
economical, that it is now profitably applied in Northumberland to
alloys too poor in silver to be treated by cupellation. This process is
founded upon the following phenomena.

After melting completely an alloy of lead and silver, if we allow it to
cool very slowly, continually stirring it meanwhile with a rake, we
shall observe at a certain period a continually increasing number of
imperfect little crystals, which may be taken out with a drainer,
exactly as we may remove the crystals of sea salt deposited during the
concentration of brine, or those of sulphate of soda, as its agitated
solution cools. On submitting to analysis the metallic crystals thus
separated, and also the liquid metal deprived of them, we find the
former to be lead almost alone, but the latter to be rich in silver,
when compared with the original alloy. The more of the crystalline
particles are drained from the metallic bath, the richer does the
_mother_ liquid become in silver. In practice, the poor lead is raised
by this means to the standard of the ordinary lead of the litharge
works; and the better lead is made ten times richer. This very valuable
alloy is then submitted to cupellation; but as it contains only a tenth
part of the quantity of lead subjected to crystallization, the loss in
the cupel will be obviously reduced to one-tenth of what it was by the
former process; that is, 7/10 of a per cent., instead of 7.

These nine-tenths of the lead separated by the drainer, are immediately
sent into the market, without other loss than the trifling one, of about
1/2 per cent., involved in reviving a little dross skimmed off the
surface of the melted metal at the beginning of the operation. Hence the
total waste of lead in this method does not exceed 2 per cent. And as
only a small quantity of lead requires to be cupelled, this may be done
with the utmost slowness and circumspection; whereby loss of the
precious metal, and injury to the health of the workpeople, are equally
avoided.

The crystallization refinery of Mr. Pattinson is an extremely simple
smelting-house. It contains 3 hemispherical cast-iron pans, 41 inches in
diameter, and 1/4 of an inch thick. The three pans are built in one
straight line, the broad flange at their edge being supported upon
brickwork. Each pan has a discharge pipe, proceeding laterally from one
side of its bottom, by which the melted metal may be run out when a plug
is withdrawn, and each is heated by a small separate fire.

Three tons of the argentiferous lead constitute one charge of each pan;
and as soon as it is melted, the fire is withdrawn; the flue,
grate-door, and ash-pit, are immediately closed, and made air-tight with
bricks and clay-lute. The agitation is now commenced, with a round bar
of iron terminated with a chisel point, the workman being instructed
merely to keep moving that simple rake constantly in the pan, but more
especially towards the edges, where the solidification is apt to begin.
He must be careful to take out the crystals, progressively as they
appear, with an iron drainer, heated a little higher than the
temperature of the metal bath. The liquid metal lifted in the drainer,
flows readily back through its perforations, and may be at any rate
effectually detached by giving the ladle two or three jogs. The solid
portion remains in the form of a spongy, semi-crystalline, semi-pasty
mass.

The proportion of crystals separated at each melting, depends upon the
original quality of the alloy. If it be poor, it is usually divided in
the proportion of two-thirds of poor crystals, and one-third of rich
liquid metal; but this proportion is reversed if the alloy contain a
good deal of silver.

Let us exemplify, by the common case of a lead containing 10 ounces of
silver per ton. Operating upon three tons of this alloy, or 60 cwt.,
containing 30 oz. of silver, there will be obtained in the first
operation--

  (_a_) 40 cwt. at 4-1/4 ounces of silver per ton; in whole 9 oz.}30 oz.
  (_b_) 20 cwt. at 21               --             --      21    }

Each of these alloys (_a_) and (_b_) will be joined to alloys of like
quality obtained in the treatment of one or several other portions of
three tons of the primitive alloy. Again, three tons of each of these
rich alloys are subjected to the crystallization process, and thus in
succession. Thus poorer and poorer lead is got on the one hand, and
richer and richer alloys on the other. Sometimes the _mother_ metal is
parted from a great body of poor crystals, by opening the
discharge-pipe, and running off the liquid, while the workman keeps
stirring, to facilitate the separation of the two.

25 fodders, 15 cwts., 49 lbs. = 540 cwts., 49 lbs. of alloy, holding 5
oz. of silver per fodder, in the whole 130 oz., afforded, after three
successive crystallizations--

                                                                   oz.
  440 cwts. of poor lead, holding 1/2 oz. of silver per fodder;
      in all                                                      10-1/2
   15 cwt. 49     --      holding the original quantity, nearly    3-1/2
   84 cwts. of lead for the cupel, holding 29 oz.                116
                                                                 -------
                      Total                                      130

         1 cwt. of loss, principally in the reduction of dross.

The expenses of the new method altogether, including 3_s._ per fodder of
patent dues are about one-third of the old; being 17_l._ 13_s._ and
54_l._ 16_s._ respectively, upon 84 cwts. of lead, at 29 oz. per fodder.

In the conditions above stated, the treatment of argentiferous lead
occasions the following expenses:--

                 FOR ONE FODDER.    _£_ _s._ _d._
  By the new process                 0   13    7
         old process                 2    2    2

Admitting that the treatment of silver holding lead is economically
possible only when the profit is equal to one-tenth of the gross
expenses of the process, we may easily calculate, with the preceding
data, that it is sufficient for the lead to have the following contents
in silver:--

  With the new process, 3 ounces per fodder; or,      0·000078
  With the old process, 8-4/10 ounces per fodder; or, 0·000218

To conclude, the refining by crystallization reduces the cost of the
parting of lead and silver, in the proportion of 3 to 1; and allows of
extracting silver from a lead which contains only about 3 oz. per ton.
In England, the new method produces at present very advantageous
results, especially in reference to the great masses to which it may be
applied. In 1828, the quantity of lead annually extracted from the mines
in the United Kingdom had been progressively raised to 47,000 tons.
Reduced almost to one-half of this amount in 1832, by the competition of
the mines of la Sierra de Gador, the English production began again to
increase in 1833. In 1835, 35,000 tons of lead were obtained, one-half
of which only having a mean content of 8-1/2 oz. of silver per ton, was
subjected to cupellation, and produced 14,000 oz. of that precious
metal. The details of this production are--

  Silver extracted from 17,500 tons of lead,  } 140,000 oz.
  holding upon the average 8-1/2 oz. per ton. }
  Silver extracted from silver ores,
  properly so called, in Cornwall                36,000
                                                -------
                                                176,000

In 1837, the production of lead amounted probably to 40,000 tons; upon
which the introduction of the new method would have the effect not only
of reducing considerably the cost of parting the 20,000 tons of lead
containing 8 oz. of silver per ton, but of permitting the extraction of
4 or 5 oz. of silver, which may be supposed to exist upon an average in
the greater portion of the remaining 20,000 tons. Otherwise, this mass
of the precious metal would have had no value, or have been
unproductive.

There are two oxides of silver; called argentic oxide, and suroxide, by
Berzelius. 1. The first is obtained by adding solution of caustic
potassa, or lime-water, to a solution of nitrate of silver. The
precipitate has a brownish-gray colour, which darkens when dried, and
contains no combined water. Its specific gravity is 7·143. On exposure
to the sun, it gives out a certain quantity of oxygen, and becomes a
black powder. This oxide is an energetic base; being slightly soluble in
pure water, reacting like the alkalis upon reddened litmus paper, and
displacing, from their combinations with the alkalis, a portion of the
acids, with which it forms insoluble compounds. It is insoluble in the
caustic lyes of potassa or soda. By combination with caustic ammonia, it
forms _fulminating silver_. This formidable substance may be prepared by
precipitating the nitrate of silver with lime-water, washing the oxide
upon a filter, and spreading it upon gray paper, to make it nearly dry.
Upon the oxide, still moist, water of ammonia is to be poured, and
allowed to remain for several hours. The powder which becomes black, is
to be freed from the supernatant liquor by decantation, divided into
small portions while moist, and set aside to dry upon bits of porous
paper. Fulminating silver may be made more expeditiously by dissolving
the nitrate in water of pure ammonia, and precipitating by the addition
of caustic potassa lye in slight excess. If fulminating silver be
pressed with a hard body in its moist state, it detonates with
unparalleled violence; nay, when touched even with a feather, in its dry
state, it frequently explodes. As many persons have been seriously
wounded, and some have been killed, by these explosions, the utmost
precautions should be taken, especially by young chemists, in its
preparation. This violent phenomenon is caused by the sudden production
of water and nitrogen, at the instant when the metallic oxide is
reduced. The quiescent and divellent affinities seem to be so nicely
balanced in this curious compound, that the slightest disturbance is
sufficient to incite the hydrogen of the ammonia to snatch the oxygen
from the silver. The oxide of silver dissolves in glassy fluxes, and
renders them yellow. It consists, according to Berzelius, of 93·11 parts
of silver, and 6·89 of oxygen. 2. The suroxide of silver is obtained by
passing a voltaic current through a weak solution of the nitrate; it
being deposited, of course, at the positive or oxygenating pole. It is
said to crystallize in needles of a metallic lustre, interlacing one
another, which are one-third of an inch long. When thrown into muriatic
acid, it causes the disengagement of chlorine, and the formation of
chloride of silver; into water of ammonia, it occasions such a rapid
production of nitrogen gas, with a hissing sound, as to convert the
whole liquid into froth. If a little of it, mixed with phosphorus, be
struck with a hammer, a loud detonation ensues. With heat it
decrepitates, and becomes metallic silver.

Sulphuret of silver, which exists native, may be readily prepared by
fusing the constituents together; and it forms spontaneously upon the
surface of silver exposed to the air of inhabited places, or plunged
into eggs, especially rotten ones. The tarnish may be easily removed, by
rubbing the metal with a solution of _cameleon mineral_, prepared by
calcining peroxide of manganese with nitre. Sulphuret of silver is a
powerful sulpho-base; since though it be heated to redness in close
vessels, it retains the volatile sulphides, whose combinations with the
alkalis are decomposed at that temperature. It consists of 87·04 of
silver, and 12·96 of oxygen.

A small quantity of tin, alloyed with silver, destroys its ductility.
The best method of separating these two metals, is to laminate the alloy
into thin plates, and distil them along with corrosive sublimate. The
bichloride of tin comes over in vapours, and condenses in the receiver.
Silver and lead, when combined, are separated by heat alone in the
process of cupellation, as described in the article ASSAY, and in the
reduction of silver ores. See _suprà_.

An alloy, containing from one-twelfth to one-tenth of copper,
constitutes the silver coin of most nations; being a harder and more
durable metal under friction than pure silver. When this alloy is boiled
with a solution of cream of tartar and sea-salt, or scrubbed with water
of ammonia, the superficial particles of copper are removed, and a
surface of fine silver is left.

Chloride of silver is obtained by adding muriatic acid, or any soluble
muriate, to a solution of nitrate of silver. A curdy precipitate falls,
quite insoluble in water, which being dried and heated to dull redness,
fuses into a semi-transparent gray mass, called, from its appearance,
_horn-silver_. Chloride of silver dissolves readily in water of ammonia,
and crystallizes in proportion as the ammonia evaporates. It is not
decomposed by a red heat, even when mixed with calcined charcoal; but
when hydrogen or steam is passed over the fused chloride, muriatic acid
exhales, and silver remains. When fused along with potassa (or its
carbonate), the silver is also revived; while oxygen (or also carbonic
acid) gas is liberated, and chloride of potassium is formed. Alkaline
solutions do not decompose chloride of silver. When this compound is
exposed to light, it suffers a partial decomposition, muriatic acid
being disengaged. See ASSAY by the _humid method_.

The best way of reducing the chloride of silver, says Mohr, is to mix it
with one-third of its weight of colophony (black rosin), and to heat the
mixture moderately in a crucible till the flame ceases to have a
greenish-blue colour; then suddenly to increase the fire, so as to melt
the metal into an ingot.

The subchloride may be directly formed, by pouring a solution of
deuto-chloride of copper or iron upon silver leaf. The metal is speedily
changed into black spangles, which, being immediately washed and dried,
constitute subchloride of silver. If the contact of the solutions be
prolonged, chloride would be formed.

The bromide, cyanide, fluoride, and iodide of silver, have not been
applied to any use in the arts. Sulphate of silver may be prepared by
boiling sulphuric acid upon the metal. See REFINING OF GOLD AND SILVER.
It dissolves in 88 parts of boiling water, but the greater part of the
salt crystallizes in small needles, as the solution cools. It consists
of 118 parts of oxide, combined with 40 parts of dry acid. Solutions of
the hyposulphite of potassa, soda, and lime, which are bitter salts,
dissolve chloride of silver, a tasteless substance, into liquids
possessed of the most palling sweetness, but not at all of any metallic
taste.

The iodide of silver is remarkable, like some other metallic compounds,
for changing its colour alternately with heat and cold. If a sheet of
white paper be washed over with a solution of nitrate of silver, and
afterwards with a somewhat dilute solution of hydriodate of potash, it
will immediately assume the pale yellow tint of the cold silver iodide.
On placing the paper before the fire, it will change colour from a pale
primrose to a gaudy brilliant yellow, like the sun-flower; and on being
cooled, it will again resume the primrose hue. These alternations may be
repeated indefinitely, like those with the salts of cobalt, provided
too great a heat be not applied. The pressure of a finger upon the hot
yellow paper makes a white spot, by cooling it quickly.

Fulminate of silver is prepared in the same way as FULMINATE _of
Mercury_, which see.

On the 10th of February, 1798, the Lords of the Privy Council appointed
the Hon. Charles Cavendish, F. R. S., and Charles Hatchett, Esq., F. R.
S., to make investigations upon the wear of gold coin by friction. Their
admirable experiments were begun in the latter end of 1798, and
completed in April 1801, having been instituted and conducted with every
mechanical aid, as devised by these most eminent chemical philosophers,
and provided, at no small expense, by the government. The following are
the important conclusions of their official report:--[54]

  [54] It is inserted in the Philosophical Transactions for 1803.

“Gold made standard by a mixture of equal parts of silver and copper, is
not so soft as gold alloyed only with silver; neither is it so pale; for
it appears to be less removed from the colour of fine gold, than either
the former or the following metal.

“Gold, when alloyed with silver and copper, when annealed, does not
become black, but brown; and this colour is more easily removed by the
blanching liquor, or solution of alum, than when the whole of the alloy
consists of copper. It may also be rolled and stamped with great
facility; and, under many circumstances, it appears to suffer less by
friction than gold alloyed by silver or copper alone.

“If copper alone forms the alloy, it must be dissolved and separated
from the surface of each piece of coin, in the process of annealing and
blanching.

“Upon a comparison of the different qualities of the three kinds of
standard gold, it appears (strictly speaking) that gold made standard by
silver and copper is rather to be preferred for coin.”

It will, undoubtedly, seem not a little strange to the uninitiated, that
this report, and its important deductions, should have been of late
years entirely set at nought, without any scientific reason or research,
apparently for the purpose of giving a certain official in our Mint a
good job, in sweating out all the silver from our sovereigns, and
replacing it, in the new coinage, with copper, taking on an average
3_d._ worth of silver out of each ounce of our excellent gold coin, and
charging the country 6-1/2_d._ for its extraction, besides the very
considerable expense in providing fine copper to replace the silver. The
pretence set up for this extraordinary degradation of the gold, was,
that our coin might peradventure be exported, in order to be de-silvered
abroad, a danger which could have been most readily averted, by leaving
out as much gold in every sovereign as was equivalent to the silver
introduced, and thus preserving its intrinsic value in precious metal.
When the film of fine gold which covers each of our present pieces has
been rubbed off from the prominent parts, these must appear of a very
different and deeper colour than the flat part or ground of the coin.
“The reason, therefore, is sufficiently apparent, says Mr. Hatchett, why
gold which is alloyed with silver only, cannot be liable to this
blemish;” and with one-half of silver alloy, it must be much less liable
to it, than with copper alone. Why did the political economists in the
recent Committee of the House of Commons on the Mint, blink this
question, of public economy and expediency?

Gold, as imported from America, Asia, and Africa, contains on an average
nearly the right proportion of silver for making the best coin; and were
it alloyed to our national standard, of 22 parts of gold, 1 of silver,
and 1 of copper, as defined by Messrs. Cavendish and Hatchett, then by
simply adding the deficient quantities of one or two of these metals, by
the rule of alligation, the very considerable expense would be saved to
the nation, and sulphureous nuisance to the Tower Hamlets, now foolishly
incurred in de-silvering and cuprifying sovereigns at the Royal Mint.

It was long imagined in Europe, that the average metallic contents of
the silver ores of Mexico and Peru, were considerably greater than those
of Saxony and Hungary. Much poorer ores, however, are worked among the
Cordilleras than in any part of Europe. The mean product of the whole
silver ores that are annually reduced in Mexico, amounts only to from
0·18 to 0·25 of a per cent.; that is, from 3 to 4 ounces in 100 lbs.;
the true average being, perhaps, not more than 2-1/2. It is by their
greater profusion of ores, not their superior richness, that the mines
of South America surpass those of Europe.

GOLD and SILVER produced in Forty Years, from 1790 to 1830.

  +------------+------------+--------------+
  |            |    Gold.   |   Silver.    |
  |            +------------+--------------+
  |Mexico      |_£_6,436,453|_£_139,818,032|
  |Chile       |   2,768,488|     1,822,924|
  |Buenos Ayres|   4,024,895|    27,182,673|
  |Russia      |   3,703,743|     1,502,981|
  +------------+------------+--------------+

RETURNS of the DOLLARS coined at the different Mints in MEXICO.

  +-----------+----------+----------+----------+----------+
  |           |   1829.  |   1830.  |   1831.  |   1834.  |
  |           +----------+----------+----------+----------+
  |Mexico     | 1,280,000| 1,090,000| 1,386,000|   952,000|
  |Guanajuato | 2,406,000| 2,560,000| 2,603,000| 2,703,000|
  |Zacatecas  | 4,505,000| 5,190,000| 4,965,000| 5,527,000|
  |Guadalaxara|   596,000|   592,000|   590,000|   715,000|
  |Durango    |   659,000|   453,000|   358,000| 1,215,000|
  |San Luis   | 1,613,000| 1,320,000| 1,497,000|   928,000|
  |Ilalpan    |   728,000|    90,000|   323,000|          |
  |           +----------+----------+----------+----------+
  |     Total |11,787,000|11,295,000|11,722,000|12,040,000|
  +-----------+----------+----------+----------+----------+

The returns for 1832 and 1833 are wanting.

PERU.--RETURNS of GOLD and SILVER coined at the Mints of Lima and Casco.

  +-----+-------+---------+------------------+
  |     | Gold. | Silver. |Total, in Dollars.|
  |     +-------+---------+------------------+
  |1830 |180,000|2,015,000|    2,195,000     |
  |1831 | 92,000|2,384,000|    2,476,000     |
  |1832 | 94,000|3,210,000|    3,284,000     |
  |1833 |150,000|2,990,000|    3,140,000     |
  |1834 |110,000|3,150,000|    3,260,000     |
  +-----+-------+---------+------------------+

RETURNS of SILVER in BARS produced at the different Smelting-works in
PERU.

  +----+-------+-------+---------+-------+-------+-------+---------+
  |    |Lima.  |Truxil-|Pasco.   |Aya-   |Puno.  |Are-   |Total, in|
  |    |       |lo.    |         |cucho. |       |quipa. |Dollars. |
  |    +-------+-------+---------+-------+-------+-------+---------+
  |1830|270,000|190,000|  780,000|120,000|250,000|150,000|1,760,000|
  |1831|270,000| 60,000|1,110,000| 70,000|310,000|110,000|1,930,000|
  |1832|290,000|100,000|1,800,000| 70,000|345,000| 25,000|2,640,000|
  |1833|222,000| 70,000|2,130,000| 50,000| 25,000| 65,000|2,562,000|
  +----+-------+-------+---------+-------+-------+-------+---------+

  +----+---------+-------+----------+
  |    |Coquimbo.|Huasco.| Copiano. |
  |    +---------+-------+----------+
  |1831|  785,000|115,000|  670,000 |
  |1832|  316,000|       |   36,000 |
  |1833|  490,000|100,000|  585,000 |
  |    +---------+-------+----------+
  |    |1,591,000|215,000|1,291,000 |
  +----+---------+-------+----------+

SANTIAGO--Mint Coinage.

             Gold.                        Silver.           Total.
  1832, 174,000; 1833, 392,500  1832, 42,000; 1833, 92,000  700,500

The production of SILVER in the kingdom of SAXONY, amounted to--

  59,231 marcs and  8 loths, in the year 1825
  55,023                                 1826
  60,034                                 1827
  61,361                                 1828
  65,176       and 10 loths              1830
  65,886                                 1832

The mine of Himmelsfürst alone produces annually 10,000 marcs.

The quantity of SILVER produced in the PRUSSIAN states was--

  22,135 marcs in 1825
  20,071          1826
  18,631          1827
  21,731          1828
  20,612          1829
  20,887          1830
  19,031          1831
  22,083          1832

The whole annual production of Europe, and Asiatic Russia, has been
rated by Humboldt at 292,000 marcs; by other authorities, at 310,000;
while at the beginning of the present century, that of the Spanish
colonies in America was 3,349,160 marcs, or nearly twelve times as
much. The sum total is 3,704,160 marcs, of 3609 grains troy each; which
is nearly 1,900,000 lbs. avoirdupois; that is, little less than 9000
tons.

The English Mint silver contains 222 pennyweights of fine silver, and 18
of copper, in the troy pound of 240 pennyweights; or 92·5 in 100 parts.
1 pound troy = 5760 grains, contains 65·8 shillings, each weighing 87·55
grains. The French silver coin contains one-tenth of copper, and a franc
weighs 5 grammes = 77·222 grains troy. The Prussian dollar, (_thaler_),
is the standard coin; 10-1/2 _thaler_ weigh 1 marc; hence, 1 _thaler_
weighs 343·7 grains troy, and contains 257·9 grains of fine silver;
being 75 per cent. of silver, and 25 of alloy. The Austrian coin
contains 13/288 of alloy, according to Wasserberg; which is only 4-1/2
per cent.


SILVER LEAF, is made in precisely the same way as GOLD LEAF, to which
article I must therefore refer the reader.


SILVERING, is the art of covering the surfaces of bodies with a thin
film of silver. When silver leaf is to be applied, the methods
prescribed for gold leaf are suitable. Among the metals, copper or brass
are those on which the silverer most commonly operates. Iron is seldom
silvered; but the processes for both metals are essentially the same.

The principal steps of this operation are the following:--

1. The _smoothing down_ the sharp edges, and polishing the surface of
the copper; called _émorfiler_ by the French artists.

2. The _annealing_; or, making the piece to be silvered redhot, and then
plunging it in very dilute nitric acid, till it be bright and clean.

3. _Pumicing_; or, clearing up the surface with pumice-stone and water.

4. The _warming_, to such a degree merely as, when it touches water, it
may make a slight hissing sound; in which state it is dipped in the very
weak aquafortis, whereby it acquires minute insensible asperities,
sufficient to retain the silver leaves that are to be applied.

5. The _hatching_. When these small asperities are inadequate for giving
due solidity to the silvering, the plane surfaces must be hatched all
over with a graving tool; but the chased surfaces need not be touched.

6. The _bluing_, consists in heating the piece till its copper or brass
colour changes to blue. In heating, they are placed in hot tools made of
iron, called _mandrins_ in France.

7. The _charging_, the workman’s term for silvering. This operation
consists in placing the silver leaves on the heated piece, and fixing
them to its surface by burnishers of steel, of various forms. The
workman begins by applying the leaves double. Should any part darken in
the heating, it must be cleared up by the scratch-brush.

The silverer always works two pieces at once; so that he may heat the
one, while burnishing the other. After applying two silver leaves, he
must heat up the piece to the same degree as at first, and he then fixes
on with the burnisher four additional leaves of silver; and he goes on
_charging_ in the same way, 4 or 6 leaves at a time, till he has
applied, one over another, 30, 40, 50, or 60 leaves, according to the
desired solidity of the silvering. He then burnishes down with great
pressure and address, till he has given the surface a uniform silvery
aspect.

_Silvering by the precipitated chloride of silver._--The white curd
obtained by adding a solution of common salt to one of nitrate of
silver, is to be well washed and dried. One part of this powder is to be
mixed with 3 parts of good pearlash, one of washed whiting, and one and
a half of sea salt. After clearing the surface of the brass, it is to be
rubbed with a bit of soft leather, or cork moistened with water, and
dipped in the above powder. After the silvering, it should be thoroughly
washed with water, dried, and immediately varnished. Some use a mixture
of 1 part of the silver precipitate, with 10 of cream of tartar, and
this mixture also answers very well.

Others give a coating of silver by applying with friction, in the
moistened state, a mixture of 1 part of silver-powder precipitated by
copper, 2 parts of cream of tartar, and as much common salt. The piece
must be immediately washed in tepid water very faintly alkalized, then
in slightly warm pure water, and finally wiped dry before the fire. See
PLATED MANUFACTURE.

The inferior kinds of plated buttons get their silver coating in the
following way:--

2 ounces of chloride of silver are mixed up with 1 ounce of corrosive
sublimate, 3 pounds of common salt, and 3 pounds of sulphate of zinc,
with water, into a paste. The buttons being cleaned, are smeared over
with that mixture, and exposed to a moderate degree of heat, which is
eventually raised nearly to redness, so as to expel the mercury from the
amalgam, formed by the reaction of the horn silver and the corrosive
sublimate. The copper button thus acquires a silvery surface, which is
brightened by clearing and burnishing.

Leather is silvered by applying a coat of parchment size, or spirit
varnish, to the surface, and then the silver leaf, with pressure.


SIMILOR, is a golden-coloured variety of brass.

[Illustration: 1030 1031]


SINGEING OF WEBS. The old furnace for singeing cotton goods is
represented in longitudinal section, _fig._ 1030., and in a transverse
one in _fig._ 1031. _a_ is the fire-door; _b_, the grate; _c_, the
ash-pit; _d_, a flue, 6 inches broad, and 2-1/2 high, over which a
hollow semi-cylindrical mass of cast iron _e_, is laid, one inch thick
at the sides, and 2-1/2 thick at the top curvature. The flame passes
along the fire-flue _d_, into a side opening _f_, in the chimney. The
goods are swept swiftly over this ignited piece of iron, with
considerable friction, by means of a wooden roller, and a swing frame
for raising them at any moment out of contact.

In some shops, semi-cylinders of copper, three quarters of an inch
thick, have been substituted for those of iron, in singeing goods prior
to bleaching them. The former last three months, and do 1500 pieces with
one ton of coal; while the latter, which are an inch and a half thick,
wear out in a week, and do no more than from 500 to 600 pieces with the
same weight of fuel.

In the early part of the year 1818, Mr. Samuel Hall enrolled the
specification of a patent for removing the downy fibres of the cotton
thread from the interstices of bobbin-net lace, or muslins, which he
effected by singeing the lace with the flame of a gas-burner. The second
patent granted to Mr. Hall, in April, 1823, is for an improvement in the
above process; viz., causing a strong current of air to draw the flame
of the gas through the interstices of the lace, as it passes over the
burner, by means of an aperture in a tube placed immediately above the
row of gas-jets, which tube communicates with an air-pump or exhauster.

[Illustration: 1032]

_Fig._ 1032. shows the construction of the apparatus complete, and
manner in which it operates; _a_, _a_, is a gas-pipe, supplied by an
ordinary gasometer; from this pipe, several small ones extend upwards to
the long burner _b_, _b_. This burner is a horizontal tube, perforated
with many small holes on the upper side, through which, as jets, the gas
passes; and when it is ignited, the bobbin-net lace, or other material
intended to be singed, is extended and drawn rapidly over the flame, by
means of rollers, which are not shown in the figure.

The simple burning of the gas, even with a draught chimney, as in the
former specification, is found not to be at all times efficacious; the
patentee, therefore, now introduces a hollow tube _c_, _c_, with a slit
or opening, immediately over the row of burners; and this tube, by means
of the pipes _d_, _d_, _d_, communicates with the pipe _e_, _e_, _e_,
which leads to the exhausting apparatus.

This exhausting apparatus consists of two tanks, _f_ and _g_, nearly
filled with water, and two inverted boxes or vessels, _h_ and _i_, which
are suspended by rods to the vibrating beam _k_; each of the boxes is
furnished with a valve opening upwards; _l_, _l_, are pipes extending
from the horizontal part of the pipe _e_, up into the boxes or vessels
_h_ and _i_, which pipes have valves at their tops, also opening upward.
When the vessel _h_ descends, the water in the tank forces out the air
contained within the vessel at the valve _m_; but when that vessel rises
again, the valve _m_ being closed, the air is drawn from the pipe _e_,
through the pipe _l_. The same takes place in the vessel _i_, from which
the air in its descent is expelled through the valve _n_, and, in its
ascent, draws the air through the pipe _l_, from the pipe _e_. By these
means, a partial exhaustion is effected in the pipe _e_, _e_, and the
tube _c_, _c_; to supply which, the air rushes with considerable force
through the long opening of the tube _c_, _c_, and carries with it the
flame of the gas-burners. The bobbin-net lace, or other goods, being now
drawn over the flame between the burner _b_, _b_, and the exhausted tube
_c_, _c_, by means of rollers, as above said, the flame of the gas is
forced through the interstices of the fabric, and all the fine filaments
and loose fibres of the thread are burnt off, without damaging the
substance of the goods.

To adjust the draught from the gas-burners, there are stopcocks
introduced into several of the pipes _d_; and to regulate the action of
the exhausting apparatus, an air vessel _o_, is suspended by a cord or
chain passing over pulleys, and balanced by a weight _p_. There is also
a scraper introduced into the tube _c_, which is made, by any convenient
contrivance, to revolve and slide backwards and forwards, for the
purpose of removing any light matter that may arise from the goods
singed, and which would otherwise obstruct the air passage. Two of these
draught tubes _c_, may be adapted and united to the exhausting
apparatus, when a double row of burners is employed, and the inclination
of the flame may be directed upwards, downwards, or sideways, according
to the position of the slit in the draft tube, by which means any
description of goods may, if required, be singed on both sides at one
operation.

The greater part of the bobbin-net lace made in England, is sent to Mr.
Hall’s works, at Basford, near Nottingham, to be singed; and at a
reduction of price truly wonderful. He receives now only one farthing
for what he originally was paid one shilling.


SKIN (_Peau_, Fr.; _Haut_, Germ.); the external membrane of animal
bodies, consists of three layers: 1. the epidermis, scarf-skin,
(_Oberhaut_, Germ.); 2. the vascular organ, or papillary body, which
performs the secretions; and 3. the true skin, (_Lederhaut_, Germ.), of
which leather is made. The skin proper, or dermoid substance, is a
tissue of innumerable very delicate fibres, crossing each other in every
possible direction, with small orifices between them, which are larger
on its internal than on its external surface. The conical channels thus
produced, are not straight, but oblique, and filled with cellular
membrane; they receive vessels and nerves which pass out through the
skin (_cutis vera_), and are distributed upon the secretory organ. The
fibrous texture of the skin is composed of the same animal matter as the
serous membranes, the cartilages, and the cellular tissue; the whole
possessing the property of dissolving in boiling water, and being,
thereby, converted into glue. See GLUE, LEATHER, and TAN.


SLAG (_Laitier_, Fr.; _Schlacke_, Germ.); is the vitreous mass which
covers the fused metals in the smelting-hearths. In the iron-works it is
commonly called _cinder_. Slags consist, in general, of bi-silicates of
lime and magnesia, along with the oxides of iron and other metals; being
analogous in composition, and having the same crystalline form as the
mineral, _pyroxene_. See COPPER and IRON.


SLATES (_Ardoises_, Fr.: _Schiefern_, Germ.) The substances belonging to
this class may be distributed into the following species:--

  1. Mica-slate, occasionally used for covering houses.
  2. Clay-slate, the proper roofing-slate.
  3. Whet-slate.
  4. Polishing-slate.
  5. Drawing-slate, or black chalk.
  6. Adhesive slate.
  7. Bituminous shale.
  8. Slate-clay.

1. _Mica-slate._--This is a mountain rock of vast continuity and extent,
of a schistose texture, composed of the minerals mica and quartz, the
mica being generally predominant.

2. _Clay-slate._--This substance is closely connected with mica; so that
uninterrupted transitions may be found between these two rocks in many
mountain chains. It is a simple schistose mass, of a bluish-gray or
grayish-black colour, of various shades, and a shining, somewhat pearly
internal lustre on the faces, but of a dead colour in the cross
fracture.

Clay-slate is extensively distributed in Great Britain. It skirts the
Highlands of Scotland, from Lochlomond by Callender, Comrie, and
Dunkeld; resting on, and gradually passing into mica-slate throughout
the whole of that territory. Roofing-slate occurs, on the western side
of England, in the counties of Cornwall and Devon; in various parts of
North Wales and Anglesea; in the north-east parts of Yorkshire, near
Ingleton, and in Swaledale; as also in the counties of Cumberland and
Westmorland. It is likewise met with in the county of Wicklow and other
mountainous districts of Ireland.

All the best beds of roofing-slate improve in quality as they lie deeper
under the surface; near to which, indeed, they have little value.

A good roofing-slate should split readily into thin even laminæ; it
should not be absorbent of water either on its face or endwise, a
property evinced by its not increasing perceptibly in weight after
immersion in water; and it should be sound, compact, and not apt to
disintegrate in the air. The slate raised at Eisdale, on the west coast
of Argyllshire, is very durable.

_Cleaving and dressing of the slates._--The splitter begins by dividing
the block, cut lengthwise, to a proper size, which he rests on end, and
steadies between his knees. He uses a mallet and a chisel, which he
introduces into the stone in a direction parallel to the _folia_. By
this means he reduces it into several manageable pieces, and he gives to
each the requisite length, by cutting cross grooves on the flat face,
and then striking the slab with the chisel. It is afterwards split into
thinner sections, by finer chisels dexterously applied to the edges. The
slate is then dressed to the proper shape, by being laid on a block of
wood, and having its projecting parts at the ends and sides cut off with
a species of hatchet or chopping-knife. It deserves to be noticed, that
blocks of slate may lose their property of divisibility into thin
laminæ. This happens from long exposure to the air, after they have been
quarried. The workmen say, then, that they have lost their waters. For
this reason, the number of splitters ought to be always proportioned to
the number of block-hewers. Frost renders the blocks more fissile; but a
supervening thaw renders them quite refractory. A new frost restores the
faculty of splitting, though not to the same degree; and the workmen
therefore avail themselves of it without delay. A succession of frosts
and thaws renders the quarried blocks quite intractable.

3. _Whet-slate, or Turkey hone_, is a slaty rock, containing a great
proportion of quartz, in which the component particles, the same as in
clay-slate and mica-slate, but in different proportions, are so very
small as to be indiscernible.

4. _Polishing slate._ Colour, cream-yellow, in alternate stripes;
massive; composition impalpable; principal fracture, slaty, thin, and
straight; cross fracture, fine earthy; feels fine, but meagre; adheres
little, if at all, to the tongue; is very soft, passing into friable;
specific gravity in the dry state, 0·6; when imbued with moisture, 1·9.
It is supposed to have been formed from the ashes of burnt coal. It is
found at Planitz, near Zwickau, and at Kutschlin near Bilin in Bohemia.

5. _Drawing-slate, or black chalk_; has a grayish-black colour; is very
soft, sectile, easily broken, and adheres slightly to the tongue; spec.
grav. 2·11. The streak is glistening. It occurs in beds in primitive and
transition clay-slate; also in secondary formations, as in the
coal-measures of most countries. It is used in crayon drawing. Its trace
upon paper is regular and black. The best kinds are found in Spain,
Italy, and France. Some good black chalk occurs also in Caernarvonshire
and in the island of Islay.

6. _Adhesive slate_, has a light greenish-gray colour, is easily broken
or exfoliated, has a shining streak, adheres strongly to the tongue, and
absorbs water rapidly, with the emission of air-bubbles and a crackling
sound.

7. _Bituminous shale_, is a species of soft, sectile slate-clay, much
impregnated with bitumen, which occurs in the coal-measures.

8. _Slate-clay_, has a gray or grayish-yellow colour; is massive, with a
dull glimmering lustre from spangles of mica interspersed. Its slaty
fracture approaches at times to earthy; fragments, tabular; soft,
sectile, and very frangible; specific gravity, 2·6. It adheres to the
tongue, and crumbles down when immersed for some time in water. It is
found as an alternating bed in the coal-measures. (See the sections of
the strata under PITCOAL.) When breathed upon, it emits a strong
argillaceous odour. When free from lime and iron, it forms an excellent
material for making refractory fire-bricks, being an infusible compound
of alumina and silica; one of the best examples of which is the schist
known by the name of Stourbridge clay.


SMALL WARES, is the name given in this country to textile articles of
the tape kind, narrow bindings of cotton, linen, silk, or woollen
fabric; plaited sash cord, braid, &c. Tapes are woven upon a loom like
that for weaving ribbons, which is now generally driven by mechanical
power. Messrs. Worthington and Mulliner obtained a patent, in June,
1825, for improvements in such a loom, which have answered the purposes
of their large factory in Manchester very well; and in May, 1831, Mr.
Whitehead, of the same town, patented certain improvements in the
manufacture of small wares. The objects of the latter patent are, the
regular taking up of the tape or cloth, as it is woven, a greater
facility of varying the vibration of the lay, together with the saving
of room required for a range of looms to stand in.[55] See BRAIDING
MACHINE.

  [55] Newton’s London Journal, vol. xiii. p. 192; and vol. i. combined
  series, p. 212.


SMALT, see AZURE and COBALT.

Imported for home consumption in 1834, 162,232 lbs.; in 1835, 96,649; in
1836, 79,531; duty, 4_d._ per lb.


SMELTING, is the operation by which the ores of iron, copper, lead, &c.,
are reduced to the metallic state. See METALLURGY, ORES, and the
respective metals.


SOAP (_Savon_, Fr.; _Seife_, Germ.); is a chemical compound, of
saponified fats or oils with potash or soda, prepared for the purposes
of washing linen, &c. Fatty matters, when subjected to the action of
alkaline lyes, undergo a remarkable change, being converted into three
different acids, called stearic, margaric, and oleic; and it is these
acids, in fact, which combine with the bases, in definite proportions,
to form compounds analogous to the neutro-saline. Some chemical writers
describe under the title soap, every compound which may result from the
union of fats with the various earths and metallic oxides--a latitude of
nomenclature which common language cannot recognise, and which would
perplex the manufacturer.

Soaps are distinguished into two great classes, according to their
consistence; the hard and the soft; the former being produced by the
action of soda upon fats, the latter by that of potash. The nature of
the fats contributes also somewhat to the consistence of soaps; thus
tallow, which contains much stearine and margarine, forms with potash a
more consistent soap than liquid oils will do, which consist chiefly of
oleine. The drying oils, such as those of linseed and poppy, produce the
softest soaps.

1. _Of the manufacture of hard soap._--The fat of this soap, in the
northern countries of Europe, is usually tallow, and in the southern,
coarse olive oil. Different species of grease are saponified by soda,
with different degrees of facility; among oils, the olive, sweet almond,
rapeseed, and castor oil; and among solid fats, tallow, bone grease, and
butter, are most easily saponified. According to the practice of the
United Kingdom, six or seven days are required to complete the formation
of a pan of hard soap, and a day or two more for settling the
impurities, if it contains rosin. From 12 to 13 cwt. of tallow are
estimated to produce one ton of good soap. Some years ago, in many
manufactories the tallow used to be saponified with potash lyes, and the
resulting soft soap was converted, in the course of the process, into
hard soap, by the introduction of muriate of soda, or weak kelp lyes, in
sufficient quantity to furnish the proper quantity of soda by the
reaction of the potash upon the neutral salts. But the high price of
potash, and the diminished price as well improved quality of the crude
sodas, have led to their general adoption in soap-works. The soda-ash
used by the soap-boiler, contains in general about 36 per cent. of real
soda, in the state of dry carbonate, mixed with muriate of soda, and
more or less undecomposed sulphate. I have met lately with soda-ash,
made from sulphate of soda, in which the materials had been so ill
worked, and so imperfectly decomposed, as to contain 16 per cent. of
sulphate, a circumstance equally disgraceful, as it was ruinous to the
soda manufacturer. The barillas from Spain and Teneriffe contain from 18
to 24 per cent. of real soda. The alkali in both states is employed in
England; barilla being supposed by many to yield a finer white or curd
soap, on account of its freedom from sulphur.

The crude soda of either kind being ground, is to be stratified with
lime in cylindrical cast-iron vats, from 6 to 7 feet wide, and from 4 to
5 feet deep; the lowest layer consisting, of course, of unslaked or
shell quicklime. The vats have a false bottom, perforated with holes,
and a lateral tubulure under it, closed commonly with a wooden plug,
similar to the _épine_ of the French soap pans, by which the lyes
trickle off clear and caustic, after infiltration through the beds of
lime. The quantity of lime must be proportional to the carbonic acid in
the soda.

Upon 1 ton of tallow put into the soap pan, about 200 gallons of soda
lye, of specific gravity 1·040, being poured, heat is applied, and after
a very gentle ebullition of about 4 hours, the fat will be found to be
completely saponified, by the test of the spatula, trowel, or pallet
knife; for the fluid lye will be seen to separate at once upon the steel
blade, from the soapy paste. Such lyes, if composed of pure caustic
soda, would contain 4 per cent. of alkali; but from the presence of
neutro-saline matter, they seldom contain so much as 2 per cent.; in
fact, a gallon may be estimated to contain not more than 2 ounces; so
that 200 gallons contain 25 pounds of real soda. The fire being
withdrawn from the soap pan, the mass is allowed to cool during one
hour, or a little more, after which the spent lyes, which are not at all
alkaline, are run off by a spigot below, or pumped off above, by a pump
set into the pan. A second similar charge of lye is now introduced into
the pan, and a similar boiling process is renewed. Three such boils may
be given in the course of one day’s work, by an active soap-maker. Next
day the same routine is resumed with somewhat stronger lyes, and so
progressively, till, towards the sixth day, the lye may have the density
of 1·160, and will be found to contain 6 per cent. of real soda.[56]
Were the lye a solution of pure caustic soda, it would contain at this
density no less than 14-3/4 per cent. of alkali. The neutro-saline
matter present in the spent lye is essential to the proper granulation
and separation of the saponaceous compound; for otherwise the watery
menstruum would dilute and even liquefy the soap. Supposing 12-1/2 cwt.
of tallow to yield upon an average 20 cwt. of hard soap, then 20 cwt. of
tallow will produce 32 cwt.; and as its average contents in soda are 6
per cent., these 32 cwt. should require 1·52 cwt. of real soda for their
production. If barilla at 20 per cent. be the alkali employed, then 7·6
cwt. of barilla must be consumed in the said process. If the alkali be
soda-ash of 40 per cent., half the weight will of course suffice. I have
reason to believe that there is great waste of alkali incurred in many
soap-works, as 6 cwt. of soda-ash, of at least 30 per cent., is often
expended in making 1 ton of soap, being 50 per cent. more than really
enters into the composition of the soap.

  [56] According to my own experiments upon the soda lye used in the
  London soap-works.

The barillas always contain a small proportion of potash, to which their
peculiar value, in making a less brittle or more plastic hard soap than
the factitious sodas, may with great probability be ascribed. Chemistry
affords many analogies, especially in mineral waters, where salts,
apparently incompatible, co-exist in dilute solutions. We may thus
conceive how a small quantity of stearate or oleate of potash may resist
the decomposing action of the soda salts. The same modification of the
consistence of hard soap may, however, be always more conveniently
produced by a proper admixture of oleine with stearine.

Soda which contains sulphurets is preferred for making the mottled or
marbled soap, whereas the desulphuretted soda makes the best white curd
soap. Mottling is usually given in the London soap-works, by introducing
into the nearly finished soap in the pan a certain quantity of the
strong lye of crude soda, through the rose spout of a watering-can. The
dense sulphuretted liquor, in descending through the pasty mass, causes
the marbled appearance. In France a small quantity of solution of
sulphate of iron is added during the boiling of the soap, or rather with
the first service of the lyes. The alkali seizes the acid of the
sulphate, and sets the protoxide of iron free, to mingle with the paste,
to absorb more or less oxygen, and to produce thereby a variety of
tints. A portion of oxide combines also with the stearine to form a
metallic soap. When the oxide passes into the red state, it gives the
tint called _manteau Isabelle_. As soon as the _mottler_ has broken the
paste, and made it pervious in all directions, he ceases to push his
rake from right to left, but only plunges it perpendicularly, till he
reaches the lye; then he raises it suddenly in a vertical line, making
it act like the stroke of a piston in a pump, whereby he lifts some of
the lye, and spreads it over the surface of the paste. In its subsequent
descent through the numerous fissures and channels, on its way to the
bottom of the pan, the coloured lye impregnates the soapy particles in
various forms and degrees, whence a varied marbling results.

Three pounds of olive oil afford five pounds of marbled Marseilles soap
of good quality, and only four pounds four ounces of white soap; showing
that more water is retained by the former than the latter. Oil of
grains, as linseed and rapeseed, do not afford so solid a soda soap as
oil of olives; but tallow affords a still harder soap with soda. Some of
the best Windsor soap made in London contains one part of olive oil
(gallipoli) for every nine parts of tallow. Much of the English hard
soap is made with kitchen and bone fat, of a very coarse quality; the
washing of the numerous successive lyes, however, purifies the foul
fats, and deprives them of their offensive smell in a great degree. It
is common now at Marseilles to mix ten per cent. of the oil of grains
with olive oil; for which purpose a large proportion of the oils
extracted from seeds in the mills of the _Department du Nord_ is sent to
Marseilles; but five per cent. of poppy-seed oil, mixed with tallow,
renders the soap made with the mixture stringy and unfit for washing;
because the two species of fat refuse to amalgamate.

The affinity between the stearine of tallow and the alkali, is so great
that a soap may be speedily made from them in the cold. If we melt
tallow at the lowest possible temperature, and let it cool to the fixing
point, then add to it half its weight of caustic lye, at 36° B.,
agitating meanwhile incessantly with a pallet knife, we shall perceive,
at the end of some hours of contact, the mixture suddenly acquire a very
solid consistence, and at the same moment assume a marked elevation of
temperature, proving the phenomenon to be due to chemical attraction. In
some trials of this kind, the thermometer has risen from 54° to 140° F.

According to recent experiments made in Marseilles, 100 pounds of olive
oil take, for their conversion into soap, 54 pounds of crude soda, of 36
per cent. alkaline strength. One part of lime is employed for rendering
three parts of the soda caustic. The richer the oil is in stearine, the
more dilute should be the lye used in the saponification; and _vice
versâ_ when it abounds in oleine. For oil of the former kind, the first
lyes added have a density of from 8° to 9° B.; but for the latter kind,
the density is from 10° to 11°. When four parts of olive oil are mixed
with one part of poppy, rape, or linseed oil, as is now the general
practice at Marseilles, then for such a mixture the first lyes have
usually a specific gravity of from 20° to 25°, the second from 10° to
15°, and the third from 4° to 5°, constituting a great difference from
the practice in Great Britain, where the weaker lyes are generally
employed at the commencement. The chief reason for this practice is,
however, to be found in the more complete causticity of the weak than of
the strong lyes, according to the slovenly way in which most of our
soap-boilers prepare them. Indeed, one very extensive manufacturer of
soap in London assured me that the lyes should not be caustic; an
extraordinary assertion, upon which no comment need be made. In common
cases, I would recommend the first combination of the ingredients to be
made with somewhat weak, but perfectly caustic lye, and when the
saponification is fairly established, to introduce the stronger lye.

In a Marseilles soap-house, there are four lye-vats in each set: No. 1.
is the _fresh vat_, into which the fresh alkali and lime are introduced;
No. 2. is called the _avançaire_, being one step in advance; No. 3. is
the small _avançaire_, being two steps in advance, and therefore
containing _weaker_ liquor; No. 4. is called the _water_ vat, because it
receives the water directly.

Into No. 3. the moderately exhausted or somewhat spent lyes are thrown.
From No. 3. the lye is run or pumped into No. 2., to be strengthened;
and in like manner from No. 3. into No. 1. Upon the lime paste in No.
4., which has been taken from No. 3., water is poured; the lye thus
obtained is poured upon the paste of No. 3., which has been taken from
No. 2. No. 3. is twice lixiviated; and No. 2., once. The receiver under
No. 1. has four compartments; into No. 1. of which the first and
strongest lye is run; into No. 2. the second lye; into No. 3. the third
lye; and into No. 4. the fourth lye, which is so weak as to be used for
lixiviation, instead of water; (_pour d’avances_).

The lime of vat No. 4., when exhausted, is emptied out of the window
near to which it stands; in which case the water is poured upon the
contents of No. 3.; and upon No. 2. the somewhat spent lyes.

No. 1. is now the _avançaire_ of No. 4; because this has become, in its
turn, the _fresh_ vat, into which the fresh soda and quicklime are put.
The lye discharged from No. 3. comes, in this case, upon No. 2.; and
after being run through it, is thrown upon No. 1.

144 pounds of oil yield at Marseilles, upon an average, not more than
from 240 to 244 pounds of soap; or 100 pounds yield about 168; so that
in making 100 pounds of soap, at this rate nearly 60 pounds of oil are
consumed.

OF YELLOW OR ROSIN SOAP.

Rosin, although very soluble in alkaline menstrua, is not however
susceptible, like fats, of being transformed into an acid, and will not
of course saponify, or form a proper soap by itself. The more caustic
the alkali, the less consistence has the resinous compound which is made
with it. Hence fat of some kind, in considerable proportion, must be
used along with the rosin, the _minimum_ being equal parts; and then the
soap is far from being good. As alkaline matter cannot be neutralized by
rosin, it preserves its peculiar acrimony in a soap poor in fat, and is
ready to act too powerfully upon woollen and all other animal fibres to
which it is applied. It is said that rancid tallow serves to mask the
strong odour of rosin in soap, more than any oil or other species of
fat. From what we have just said, it is obviously needless to make the
rosin used for yellow soaps pass through all the stages of the
saponifying process; nor would this indeed be proper, as a portion of
the rosin would be carried away, and wasted with the spent lyes. The
best mode of proceeding, therefore, is first of all to make the hard
soap in the usual manner, and at the last service or charge of lye,
namely, when this ceases to be absorbed, and preserves in the
boiling-pan its entire causticity, to add the proportion of rosin
intended for the soap. In order to facilitate the solution of the rosin
in the soap, it should be reduced to coarse powder, and well
incorporated by stirring with the rake. The proportion of rosin is
usually from one-third to one-fourth the weight of the tallow. The boil
must be kept up for some time with an excess of caustic lye; and when
the paste is found, on cooling a sample of it, to acquire a solid
consistence, and when diffused in a little water, not to leave a
resinous varnish on the skin, we may consider the soap to be finished.
We next proceed to draw off the superfluous lyes, and to purify the
paste. For this purpose, a quantity of lyes at 80° B. being poured in,
the mass is heated, worked well with a rake, then allowed to settle, and
drained of its lyes. A second service of lyes, at 4° B., is now
introduced, and finally one at 2°; after each of which, there is the
usual agitation and period of repose. The pan being now skimmed, and the
scum removed for another operation, the soap is laded off by hand-pails
into its frame-moulds. A little palm oil is usually employed in the
manufacture of yellow soap, in order to correct the flavour of the
rosin, and brighten the colour. This soap, when well made, ought to be
of a fine wax-yellow hue, be transparent upon the edges of the bars,
dissolve readily in water, and afford, even with hard pump-water, an
excellent lather.

The frame-moulds for hard soap are composed of strong wooden bars, made
into the form of a parallelogram, which are piled over each other, and
bound together by screwed iron rods, that pass down through them. A
square well is thus formed, which in large soap factories is sometimes
10 feet deep, and capable of containing a couple of tons of soap.

Mr. Sheridan some time since obtained a patent for combining silicate of
soda with hard soap, by triturating them together in the hot and pasty
state with a crutch in an iron pan. In this way from 10 to 30 per cent.
of the silicate may be introduced. Such soap possesses very powerful
detergent qualities, but it is apt to feel hard and be somewhat gritty
in use. The silicated soda is prepared by boiling ground flints in a
strong caustic lye, till the specific gravity of the compound rises to
nearly double the density of water. It then contains about 35 grains of
silica, and 46 of soda-hydrate, in 100 grains[57].

  [57] By my own experiments upon the liquid silicate made at Mr. Gibbs’
  excellent soap factory.

Hard soap, after remaining two days in the frames, is at first divided
horizontally into parallel tablets, 3 or 4 inches thick, by a brass
wire; and these tablets are again cut vertically into oblong nearly
square bars, called wedges in Scotland.

The soap-pans used in the United Kingdom are made of cast iron, and in
three separate pieces joined together by iron-rust cement. The following
is their general form:--The two upper frusta of cones are called curbs;
the third, or undermost, is the pan, to which alone the heat is applied,
and which, if it gets cracked in the course of boiling, may easily be
lifted up within the conical pieces, by attaching chains or cords for
raising it, without disturbing the masonry, in which the curbs are
firmly set. The surface of the hemispherical pan at the bottom, is in
general about one-tenth part of the surface of the conical sides.

The white ordinary tallow soap of the London manufacturers, called curd
soap, consists, by my experiments, of--fat, 52; soda, 6; water, 42; =
100. Nine-tenths of the fat, at least, is tallow.

I have examined several other soaps, and have found their composition
somewhat different.

The foreign Castile soap of the apothecary has a specific gravity of
1·0705, and consists of--

  Soda                         9
  Oily fat                    76·5
  Water and colouring-matter  14·5
                             -----
                             100·0

English imitation of Castile soap, spec. grav. 0·9669, consists of--

  Soda                                   10·5
  Pasty-consistenced fat                 75·2
  Water, with a little colouring-matter  14·3
                                        -----
                                        100·0

A perfumer’s white soap was found to consist of--

  Soda                9
  Fatty matter       75
  Water              16
                    ---
                    100

Glasgow white soap--

  Soda                6·4
  Tallow             60·0
  Water              33·6
                    -----
                    100·0

Glasgow brown rosin soap--

  Soda                6·5
  Fat and rosin      70·0
  Water              23·5
                    -----
                    100·0

A London cocoa-nut oil soap was found to consist of--

  Soda                4·5
  Cocoa-nut lard     22·0
  Water              73·5
                    -----
                    100·0

This remarkable soap was sufficiently solid; but it dissolved in hot
water with extreme facility. It is called marine soap, because it washes
linen with sea water.

A poppy-nut-oil hard soap consisted of--

  Soda                7
  Oil                76
  Water              17
                    ---
                    100[58]

  [58] My own experiments. See Fats, Oils, and Stearine.

The soap known in France by the name of _soap in tables_ consists,
according to M. Thenard’s analysis, of--

  Soda                4·6
  Fatty matter       50·2
  Water              45·2
                    -----
                    100·0

M. D’Arcet states the analysis of Marseilles soap at--

  Soda                6
  Oil                60
  Water              34
                    ---
                    100

SOFT SOAP.

The principal difference between soaps with base of soda, and soaps with
base of potash, depends upon their mode of combination with water. The
former absorb a large quantity of it, and become solid; they are
chemical hydrates. The others experience a much feebler cohesive
attraction; but they retain much more water in a state of mere mixture.

Three parts of fat afford, in general, fully five parts of soda soap,
well dried in the open air; but three parts of fat or oil will afford
from six to seven parts of potash soap of moderate consistence. This
feebler cohesive force renders it apt to deliquesce, especially if there
be a small excess of the alkali. It is, therefore, impossible to
separate it from the lyes; and the washing or _relargage_, practised on
the hard-soap process, is inadmissible in the soft. Perhaps, however,
this concentration or abstraction of water might be effected by using
dense lyes of muriate of potash. Those of muriate or sulphate of soda
change the potash into a soda soap, by double decomposition. From its
superior solubility, more alkaline reaction, and lower price, potash
soap is preferred for many purposes, and especially for scouring woollen
yarns and stuffs.

Soft soaps are usually made in this country with whale, seal, olive, and
linseed oils, and a certain quantity of tallow; on the continent, with
the oils of hempseed, sesame, rapeseed, linseed, poppy-seed, and colza;
or with mixtures of several of these oils. When tallow is added, as in
Great Britain, the object is to produce white and somewhat solid grains
of stearic soap in the transparent mass, called figging, because the
soap then resembles the granular texture of a fig.

The potash lyes should be made perfectly caustic, and of at least two
different strengths; the weakest being of specific gravity 1·05; and the
strongest, 1·20, or even 1·25. Being made from the potashes of commerce,
which contain seldom more than 60 per cent., and often less, of real
alkali, the lyes correspond in specific gravity to double their alkaline
strength; that is to say, a solution of pure potash, of the same
density, would be fully twice as strong. The following is the process
followed by respectable manufacturers of soft soap (_savon vert_, being
naturally or artificially green,) upon the continent.

A portion of the oil being poured into the pan, and heated to nearly the
boiling point of water, a certain quantity of the weaker lye is
introduced; the fire being kept up so as to bring the mixture to a
boiling state. Then some more oil and lye are added alternately, till
the whole quantity of oil destined for the pan is introduced. The
ebullition is kept up in the gentlest manner possible, and some stronger
lye is occasionally added, till the workman judges the saponification to
be perfect. The boiling becomes progressively less tumultuous, the
frothy mass subsides, the paste grows transparent, and it gradually
thickens. The operation is considered to be finished when the paste
ceases to affect the tongue with an acrid pungency, when all milkiness
and opacity disappear, and when a little of the soap placed to cool upon
a glass-plate, assumes the proper consistency.

A peculiar phenomenon may be remarked in the cooling, which affords a
good criterion of the quality of the soap. When there is formed around
the little patch, an opaque zone, a fraction of an inch broad, this is
supposed to indicate complete saponification, and is called the
_strength_; when it is absent, the soap is said to want its _strength_.
When this zone soon vanishes after being distinctly seen, the soap is
said to have _false_ strength. When it occurs in the best form, the soap
is perfect, and may be secured in that state by removing the fire, and
then adding some good soap of a previous round, to cool it down, and
prevent further change by evaporation.

200 pounds of oil require for their saponification--72 pounds of
American potash of moderate quality, in lyes at 15° B.; and the product
is 460 pounds of well-boiled soap.

If hempseed oil have not been employed, the soap will have a yellow
colour, instead of the green, so much in request on the continent. This
tint is then given by the addition of a little indigo. This dye-stuff is
reduced to fine powder, and boiled for some hours in a considerable
quantity of water, till the stick with which the water is stirred,
presents, on withdrawing it, a gilded pellicle over its whole surface.
The indigo paste diffused through the liquid, is now ready to be
incorporated with the soap in the pan, before it stiffens by cooling.

M. Thenard states the composition of soft soap at--potash 9·5, + oil
44·0, + water 46·5, = 100.

Good soft soap of London manufacture, yielded to me--potash 8·5, + oil
and tallow 45, + water 46·5.

Belgian soft or green soap afforded me--potash 7, + oil 36, + water 57,
= 100.

Scotch soft soap, being analyzed, gave me--potash 8, + oil and tallow
47, + water 45.

Another well-made soap--potash 9, + oil and fat 34, + water 57.

A rapeseed-oil soft soap, from Scotland, consisted of--potash 10, + oil
51·66, + water 38·33.

An olive-oil (gallipoli) soft soap, from ditto, contained--potash with a
good deal of carbonic acid 10, oil 48, water 42, = 100.

A semi-hard soap, from Verviers, for fulling woollen cloth, called
_savon économique_, consisted of, potash 11·5, + fat (solid) 62, + water
26·5, = 100.

The following is a common process, in Scotland, by which good soft soap
is made:--

273 gallons of whale or cod oil, and 4 cwt. of tallow, are put into the
soap-pan, with 250 gallons of lye from American potash, of such alkaline
strength that 1 gallon contains 6600 grains of real potash. Heat being
applied to the bottom pan, the mixture froths up very much as it
approaches the boiling temperature, but is prevented from boiling over
by being beat down on the surface, within the iron curb or crib which
surmounts the cauldron. Should it soon subside into a doughy-looking
paste, we may infer that the lye has been too strong. Its proper
appearance is that of a thin glue. We should now introduce about 42
gallons of a stronger lye, equivalent to 8700 gr. of potash per gallon;
and after a short interval, an additional 42 gallons; and thus
successively till nearly 600 such gallons have been added in the whole.
After suitable boiling to saponify the fats, the proper quality of soap
will be obtained, amounting in quantity to 100 firkins of 64 pounds
each, from the above quantity of materials.

It is generally supposed, and I believe it to be true, from my own
numerous experiments upon the subject, that it is a more difficult and
delicate operation to make a fine soft soap of glassy transparency,
interspersed with the figged granulations of stearate of potash, than to
make hard soap of any kind.

Soft soap is made in Belgium as follows:--For a boil of 18 or 20 tons,
of 100 kilogrammes each, there is employed for the lyes--1500 pounds of
American potashes, and 500 to 600 pounds of quicklime.

The lye is prepared cold in cisterns of hewn stone, of which there are
usually five in a range. The first contains the materials nearly
exhausted of their alkali; and the last the potash in its entire state.
The lye run off from the first, is transferred into the second; that of
the second into the third; and so on to the fifth.

In conducting the _empatage_ of the soap, they put into the pan, on the
eve of the boiling-day, six _aimes_ (one ohm, = 30 gallons imperial,) of
oil of colza, in summer, but a mixture of that oil with linseed oil in
winter, along with two aimes of potash lye at 13° B., and leave the
mixture without heat during eight hours. After applying the fire, they
continue to boil gently till the materials cease to swell up with the
heat; after which, lye of 16° or 17° must be introduced successively, in
quantities of one quarter of an aime after another, till from 2 to 4
aimes be used. The boil is finished by pouring some lye of 20° B., so
that the whole quantity may amount to 9-1/2 aimes.

It is considered that the operation will be successful, if from the time
of kindling the fire till the finish of the boil, only five hours
elapse. In order to prevent the soap from boiling over, a wheel is kept
revolving in the pan. The operative considers the soap to be finished,
when it can no longer be drawn out into threads between the finger and
thumb. He determines if it contains an excess of alkali, by taking a
sample out during the boil, which he puts into a tin dish; where if it
gets covered with a skin, he pours fresh oil into the pan, and continues
the boil till the soap be perfect. No wonder the Belgian soap is bad,
amid such groping in the dark, without one ray of science!

SOFT TOILET SOAPS.

The soft fancy toilet soaps are divisible into two classes: 1. good
_potash soap_, coloured and scented in various ways, forms the basis of
the Naples and other ordinary soft soaps of the perfumer; 2. _pearl
soap_ (_savon nacré_), which differs from the other both in physical
aspect and in mode of preparation.

_Ordinary soft Toilet Soap._--Its manufacture being conducted on the
principles already laid down, presents no difficulty to a man of
ordinary skill and experience; the only point to be strictly attended
to, is the degree of evaporation, so as to obtain soap always of uniform
consistence. The fat generally preferred is good hog’s lard; of which 30
pounds are to be mixed with 45 pounds of a caustic lye marking 17° on
Baumé’s scale; the temperature is to be gradually raised to ebullition,
but the boil must not be kept up too long or too briskly, till after the
_empatage_ or saponification is completed, and the whole of the lye
intimately combined with the fatty particles; after this, the
evaporation of the water may be pushed pretty quickly, by a steady boil,
till copious vapours cease to rise. This criterion is observed when the
paste has become too stiff to be stirred freely. The soap should have a
dazzling snowy whiteness, provided the lard has been well refined, by
being previously triturated in a mortar, melted by a steam heat, and
then strained. The lard soap so prepared, is semi-solid, and preserves
always the same appearance. If the paste is not sufficiently boiled,
however, it will show the circumstance very soon; for in a few days the
soap will become gluey and stringy, like a tenacious mass of birdlime.
This defect may not only be easily avoided, but easily remedied, by
subjecting the paste to an adequate evaporation. Such soaps are in great
request for shaving, and are most convenient in use, especially for
travellers. Hence their sale has become very considerable.

_Pearl soft Soap._--It is only a few years since the process for making
this elegant soap became known in France. It differs little from the
preceding, and owes its beautiful aspect merely to minute manipulations,
about to be described. Weigh out 20 pounds of purified hog’s lard on the
one hand; and 10 pounds of potash lye at 36° B. on the other. Put the
lard into a porcelain capsule, gently heated upon a sand-bath, stirring
it constantly with a wooden spatula; and when it is half melted, and has
a milky appearance, pour into it only one-half of the lye, still
stirring, and keeping up the same temperature, with as little variation
as possible. While the saponification advances gradually, we shall
perceive, after an hour, some fat floating on the surface, like a film
of oil, and at the same time the soapy granulations falling to the
bottom. We must then add the second portion of the lye; whereon the
granulations immediately disappear and the paste is formed. After
conducting this operation during four hours, the paste becomes so stiff
and compact, that it cannot be stirred; and must then be lightly beaten.
At this time the capsule must be transferred from the sand-bath into a
basin of warm water, and allowed to cool very slowly.

The soap, though completely made, has yet no pearly appearance. This
physical property is developed only by pounding it strongly in a marble
mortar; whereby all its particles, which seemed previously separated,
combine to form a homogeneous paste. The perfume given to it, is always
essence of bitter almonds; on which account the soap is called _almond
cream_, _crème d’amandes_.

HARD SOAPS FOR THE TOILET.

The soaps prepared for the perfumer, are distinguished into different
species, according to the fat which forms their basis. Thus there is
soap of tallow, of hog’s lard, of oil of olives, of almonds, and palm
oil.

It is from the combination of these different sorts, mingled in various
proportions, and perfumed agreeably to the taste of the consumer, that
we owe the vast number of toilet soaps sold under so many fantastic
names. One sort is rarely scented by itself, as a mixture of several is
generally preferred; in which respect every perfumer has his peculiar
secret. Some toilet soaps, however, require the employment of one kind
more than of another.

Formerly the Windsor soap was made in France, wholly with mutton suet;
and it was accordingly of inferior value. Now, by mixing some olive oil
or lard with the suet, a very good Windsor soap is produced. I have
already stated, that the fat of the London Windsor is, nine parts of
good ox tallow, and one of olive oil. A soap made entirely with oil and
soda, does not afford so good a lather as when it contains a
considerable proportion of tallow.

The soaps made with palm oil are much used; when well made, they are of
excellent quality, and ought to enter largely into all the coloured
sorts. They naturally possess the odour of violets.

The soaps made with oil of almonds are very beautiful, and preserve the
agreeable smell of their perfume; but being expensive, are introduced
sparingly into the mixtures by most manufacturers.

Some perfumers are in the habit of making what may be called extempore
soaps, employing lyes at 36° Baumé in their formation. This method,
however, ought never to be adopted by any person who prefers quality to
beauty of appearance. Such soap is, indeed, admirably white, glistening,
contains no more water than is necessary to its constitution, and may
therefore be sold the day after it is made. But it has counterbalancing
disadvantages. It becomes soon very hard, is difficultly soluble in
water, and, if not made with tallow, does not lather well. Hog’s lard is
very commonly used, for making that soap. Twenty kilogrammes of the fat
are taken, to ten kilogrammes of soda lye, at 36° B. (specific gravity
1·324); as soon as the former is nearly fluid, 5 kilogrammes of the lye
are introduced, and the mixture is continually agitated during an hour
with a wooden spatula. The temperature should never be raised above 150°
Fahr. at the commencement of the operation; at the end of one hour, 5
other kilogrammes of lye are to be added, with careful regulation of the
heat. The paste thus formed by the union of the fat and alkali, ought to
be perfectly homogeneous, and should increase in consistence every hour,
till it becomes firm enough to be poured into the frame; during which
transfer, the essential oils destined to scent it, should be introduced.
Next day the soap is hard enough; nor does it differ in appearance from
ordinary soap, only it requires prompt manipulation to be cut into bars
and cakes; for when neglected a day or two, it may become too brittle
for that purpose, and too hard to take the impression of the stamps in
relief. Such an article gets the name of _little-pan soap_, on account
of the small quantity in which it is usually manufactured. Hard soap,
made in the common way, is, on the contrary, called _large-pan soap_.
This extemporaneous compound is now seldom or never made by respectable
manufacturers. In making Windsor soap, the admixture of olive oil is
advantageous; because, being richer in oleine than suet, it saponifies
less readily than it, and thus favours the formation of a more perfect
neutral combination. When the soap cuts, or parts from the lye, when the
paste becomes clotty, or, in the language of the operative, when the
grain makes its appearance, the fire should be immediately withdrawn,
that the impurities may be allowed to subside. This part of the
operation lasts 12 hours at least; after which, the soap, still hot,
becomes altogether fluid and perfectly neutral.

For every 1000 pounds of the paste, there must be introduced 9 pounds of
essences, mingled in the following proportions:--6 pounds of essence of
carui; 1-1/2 ditto lavender (finest); 1-1/2 ditto rosemary.

The mixture must be well stirred, in order to get completely saturated
with the perfumes; and this may be readily done without at all touching
or stirring up the subjacent lyes; in the course of two hours, the soap
may be transferred into the ordinary frames. In twenty-four hours, the
mass is usually solidified enough for cutting into bars and cakes, ready
to be stamped for sale.

The above method of scenting Windsor soap is practised only in the
largest establishments; in the smaller, the soap is pailed out of the
soap-pans, into a pan provided with a steam case or jacket, and there
mixed with the essential oils, by means of appropriate heat and
agitation.

The most fashionable toilet soaps are, the rose, the _bouquet_, the
cinnamon, the orange-flower, the musk, and the bitter almond or peach
blossom.

_Soap à la rose._--This is made of the following ingredients: 30 pounds
of olive-oil soap; 20 of good tallow soap.

Toilet soaps must be reduced to thin shavings, by means of a plane, with
its under face turned up, so that the bars may be slid along it. These
shavings must be put into an untinned copper pan, which is surrounded by
a water-bath, or steam. If the soap be old and hard, 5 pounds of water
must be added to them; but it is preferable to take fresh-made soaps,
which may melt without addition, as soap some time kept does not readily
form a homogeneous paste. The fusion is commonly completed in an hour,
or thereby, the heat being applied at 212° F., to accelerate the
progress, and prevent the dissolution of the constituent water of the
soap. For this purpose the interior pan may be covered. Whenever the
mass is sufficiently liquefied, 1-1/2 ounces of finely ground vermillion
are to be introduced, and thoroughly mixed, after which the heat may be
taken off the pan; when the following perfumes may be added with due
trituration:--3 ounces of essence of rose; 1 ditto cloves; 1 ditto
cinnamon; 2-1/2 ditto bergamot; = 7-1/2.

The scented soap being put into the frames, speedily consolidates. Some
recommend to pass the finished fused soap through a tammy cloth, in
order to free it from all clots and impurities; a very proper precaution
in the act of transferring it to the frame. If the preceding
instructions be observed, we obtain a soap perfect in every point of
view; possessing a delicious fragrance, equally rich and agreeable, a
beautiful roseate hue, and the softest detergent qualities, which
keeping cannot impair. Such a soap has, in fact, been known to retain
every property in perfection during four or five years. When the
essential oils are particularly volatile, they should not be added to
the soap till its temperature has fallen to about 140° Fahr.; but in
this case a more careful trituration is required. The economy is,
however, ill bestowed; for the cakes made of such cooler soap, are never
so homogeneous and glossy.

_Soap au bouquet._--30 pounds of good tallow soap; 4 ounces of essence
of bergamot; oil of cloves, sassafras, and thyme, 1 ounce each; neroli,
1/2 ounce. The colour is given with 7 ounces of brown ochre.

_Cinnamon Soap._--30 pounds of good tallow soap; 20 ditto of palm-oil
soap. Perfumes:--7 ounces of essence of cinnamon; 1-1/4 ditto sassafras;
1-1/4 ditto bergamot. Colour:--1 pound of yellow ochre.

_Orange-flower Soap._--30 pounds of good tallow soap; 20 ditto palm-oil
soap. Perfumes:--7-1/2 ounces essence of Portugal; 7-1/2 ditto amber.
Colour:--9-1/2 ounces, consisting of 8-1/4 of a yellow-green pigment,
and 1-1/4 of red lead.

_Musk Soap._--30 pounds of good tallow soap; 20 ditto palm-oil soap.
Perfumes:--Powder of cloves, of pale roses, gilliflower, each 4-1/2
ounces; essence of bergamot, and essence of musk, each 3-1/2 ounces.
Colour:--4 ounces of brown ochre, or Spanish brown.

_Bitter Almond Soap._--Is made by compounding, with 50 pounds of the
best white soap, 10 ounces of the essence of bitter almonds.

LIGHT SOAPS.

The apparatus employed for making these soaps, is a copper pan, heated
by a water-bath; in the bottom of the pan there is a step, to receive
the lower end of a vertical shaft, to which arms or paddles are
attached, for producing constant agitation, by causing them to revolve
among the liquefied mass. Into a pan so mounted, 50 pounds of a good oil
soap of any kind are put (for a tallow soap does not become frothy
enough), and melted by proper heat, with the addition of 3 or 4 pounds
of water. By the rapid rotation of the machine, an abundant thick lather
is produced, beginning first at the bottom, and creeping gradually
upwards to the top of the pan, when the operation should be stopped; the
soap having by this time doubled its volume. It must now be pailed off
into the frame, allowed to cool, and then cut into cakes. Such soap is
exceedingly pleasant at the wash-stand, feeling very soft upon the skin,
affording a copious thick lather, and dissolving with the greatest ease.

TRANSPARENT SOAPS.

These soaps were for a long time manufactured only in England, where the
process was kept a profound secret. They are now made every where.

Equal parts of tallow soap, made perfectly dry, and spirit of wine, are
to be put into a copper still, which is plunged in a water-bath, and
furnished with its capital and refrigeratory. The heat applied to effect
the solution should be as slight as possible, to avoid evaporating too
much of the alcohol. The solution being effected, must be suffered to
settle; and after a few hours’ repose, the clear supernatant liquid is
drawn off into tin frames, of the form desired for the cakes of soap.
These bars do not acquire their proper degree of transparency till after
a few weeks’ exposure to dry air. They are now planed, and subjected to
the proper mechanical treatment for making cakes of any form. The soap
is coloured with strong alcoholic solution of archil for the rose tint,
and of turmeric for the deep yellow. Transparent soaps, however pleasing
to the eye, are always of indifferent quality; they are never so
detergent as ordinary soaps, and they eventually acquire a disagreeable
smell.

  +---------------------------+-----------+-----------+-----------+
  | Soap charged with duty in |   1834.   |   1835.   |   1836.   |
  +---------------------------+-----------+-----------+-----------+
  |                           |  _lbs._   |  _lbs._   |  _lbs._   |
  |Hard                       |144,344,043|143,806,207|146,539,210|
  |Soft                       | 10,401,281| 12,103,109| 13,358,894|
  |                           |           |           |           |
  |Amount of duty at 1-1/2_d._|           |           |           |
  |per lb. on hard soap       | _£_902,150| _£_930,039| _£_915,861|
  |           do. at 1_d._    |           |           |           |
  |           soft soap       |     43,339|     50,429|     55,662|
  +---------------------------+-----------+-----------+-----------+


SOAPSTONE; see STEATITE.


SODA, _Caustic soda_ (_Hydrate de soude_, Fr.; _Aetznatron_, Germ.); is
an alkaline substance, used in chemical researches, in bleaching, and in
the manufacture of soap. It is prepared by boiling a solution of
crystallized carbonate of soda in 4 or 5 parts of water, with half its
weight of recently slaked and sifted lime. At the end of half an hour,
the vessel of iron, porcelain, or preferably silver, may be removed from
the fire, and covered carefully, till the calcareous matter has settled
into a solid magma at the bottom. The clear supernatant lye may be then
decanted into bottles for use in the liquid state, or evaporated, out of
contact of air, till it assumes an oily appearance, then poured upon an
iron or marble slab, broken into pieces, and put up in phials secured
with greased stoppers or corks.

Caustic soda is a white brittle mass, of a fibrous texture, a specific
gravity of 1·536, melting at a heat under redness, having a most
corrosive taste and action upon animal matters, dissolving readily in
both water and alcohol, attracting carbonic acid when exposed to the
atmosphere, but hardly any water, and falling thereby into an
efflorescent carbonate; it forms soaps with tallow, oils, wax, rosin;
dissolves wool, hair, silk, horn, alumina, silica, sulphur, and some
metallic sulphurets. It consists of 77·66 soda, and 22·34 water. A
solution of caustic soda affords no precipitate with solution of
chloride of platinum, or tartaric acid, as a solution of caustic potash
never fails to do.

The following TABLE of the quantity of CAUSTIC SODA contained in LYES of
different densities, has been given by Richter:--

  +-----+---------+
  |Spec.|  Soda   |
  |grav.|per cent.|
  +-----+---------+
  | 1·00|   0·00  |
  | 1·02|   2·07  |
  | 1·04|   4·02  |
  | 1·06|   5·89  |
  | 1·08|   7·69  |
  | 1·10|   9·43  |
  | 1·12|  11·10  |
  | 1·14|  12·81  |
  | 1·16|  14·73  |
  | 1·18|  16·73  |
  | 1·20|  18·71  |
  | 1·22|  20·66  |
  | 1·24|  22·58  |
  | 1·26|  24·47  |
  | 1·28|  26·33  |
  | 1·30|  28·16  |
  | 1·32|  29·96  |
  | 1·34|  31·67  |
  | 1·35|  32·40  |
  | 1·36|  33·08  |
  | 1·38|  34·41  |
  +-----+---------+

Soda free from water, can be obtained only by the combustion of
_sodium_, which see.


SODA, CARBONATE OF (_Kohlensaures natron_, Germ.): is the soda of
commerce in various states, either crystallized, in lumps, or in a crude
powder called soda-ash. It exists in small quantities in certain mineral
waters; as, for example, in those of Seltzer, Seydschutz, Carlsbad, and
the volcanic springs of Iceland, especially the Geyser; it frequently
occurs as an efflorescence in slender needles upon damp walls, being
produced by the action of the lime upon the sea salt present in the
mortar. The mineral soda is the sesquicarbonate, to be afterwards
described.

Of manufactured soda, the variety most antiently known is barilla, the
incinerated ash of the _Salsola soda_. This plant is cultivated with
great care by the Spaniards, especially in the vicinity of Alicant. The
seed is sown in light low soils, which are embanked towards the sea
shore, and furnished with sluices, for admitting an occasional overflow
of salt water. When the plants are ripe, the crop is cut down and dried;
the seeds are rubbed out and preserved; the rest of the plant is burned
in rude furnaces, at a temperature just sufficient to cause the ashes to
enter into a state of semi-fusion, so as to concrete on cooling into
cellular masses moderately compact. The most valuable variety of this
article is called _sweet barilla_. It has a grayish-blue colour and gets
covered with a saline efflorescence when exposed for some time to the
air. It is hard and difficult to break; when applied to the tongue, it
excites a pungent alkaline taste.

I have analyzed many varieties of barilla. Their average quantity of
free or alkalimetrical soda, is about 17 per cent.; though several
contain only 14 parts in the hundred, and a few upwards of 20. This soda
is chiefly a carbonate, with a little sulphuret and sulphite; and is
mixed with sulphate and muriate of soda, carbonate of lime, vegetable
carbon, &c.

Another mode of manufacturing crude soda, is by burning sea-weed into
kelp. Formerly very large revenues were derived by the proprietors of
the shores of the Scottish islands and Highlands, from the incineration
of sea-weed by their tenants, who usually paid their rents in kelp; but
since the tax has been taken off salt, and the manufacture of a crude
soda from it has been generally established, the price of kelp has
fallen extremely low.

The crystals of soda-carbonate, as well as the soda-ash of British
commerce, are now made altogether by the decomposition of sea salt.

SODA MANUFACTURE.

The manufacture divides itself into three branches:--1. The conversion
of sea salt, or chloride of sodium, into sulphate of soda. 2. The
decomposition of this sulphate into crude soda, called _black balls_ by
the workmen. 3. The purification of these balls, either into a dry white
soda-ash or into crystals.

[Illustration: 1033 1034 1035]

1. _The preparation of the sulphate of soda._--_Figs._ 1033, 1034, 1035.
represent the furnace for converting the muriate of soda into the
sulphate. The furnace must be built interiorly of the most refractory
fire-bricks, such as are used for glasshouses, but of the ordinary brick
size; except the bridges C, G, N, which should be formed of one mass,
such as what is called a Welsh lump. A is the ash-pit; B, the grate; C,
the first bridge, between the fire and the first calcining hearth, D, D;
F, F, is its roof; G, the second bridge, between the calcining hearth
and the decomposing hearth I, I, I; the roof of which is K, K. This
hearth I, I, is lined with a lead square pan, 5 or 6 inches deep, sloped
at the back opening, in _fig._ 1035., marked M´; which deficient part of
the upright side is filled up with two bricks placed one over the other,
as shown at _m_, _m_, _fig._ 1034., and luted with clay, to confine the
semi-liquid mass in the pan, I, I. Some manufacturers make this pan 8
inches deep, and line its bottom and sides with bricks or siliceous
sandstone, to protect the lead from the corrosive action of the acid.
There are others who consider this precaution troublesome, as the points
of the pan which become leaky are thereby concealed. In the roof of the
decomposing hearth, one or two syphon funnels R, of lead, are inserted
when the charge of acid (sulphuric) is to be poured down upon the salt
in I, I, to save the risk of any annoyance from the fumes of the
muriatic acid. O, O, is a chimney filled with round flint nodules, which
are kept continually moist by the trickling of a streamlet of water upon
the topmost layer. The muriatic gas meeting this descending film of
water upon so extensive a surface, becomes absorbed, and runs out below
in a liquid form. When the acid is required in a somewhat concentrated
state, this chimney should be made both high and capacious. Such a plan,
moreover, is very valuable for abating the nuisance caused by the
disengagement of the muriatic acid gas; which is otherwise apt to
sterilize the surrounding vegetation.

A fire being kindled in the grate B, _figs._ 1033. and 1034., 3 cwt. of
salt in powder are to be thrown by a shovel into the pan I, through the
door M, _fig._ 1035., or _m_, _m_, _fig._ 1034. Two hundred weight and a
half of oil of vitriol, of specific gravity 1·844 having been diluted
with from 25 to 30 per cent. of water, and well mixed, or 3 cwts. at 56°
Baumé, are to be slowly poured in by the funnel, and diffused among the
muriate of soda, by an occasional stir with an iron rake cased with
sheet lead. Fumes of muriatic acid will now plentifully escape, and,
passing up the condensing-shaft O, will flow down in the form of liquid
spirit of salt, and escape by the stoneware stopcock P, into the pipe of
a sunk cistern. The fire having been steadily kept up at a moderate
degree, the chemical reaction will be tolerably complete in the course
of two hours; but as this is relative to the nature of the fuel, and the
draught of the furnace, no very precise rule in point of time can be
laid down; but it is sufficient for this stage of the process, when the
fumes cease to be very dense and copious, as may be ascertained by
opening the door M, and looking in, or by the appearance at the top of
the shaft O. Over the door M´, in the opposite side of the decomposing
hearth, _fig._ 1035., there must be an arch or hood terminating in a
small chimney, 15 or 20 feet high, for the ascent of the muriatic
vapours, when the charge is drawn or run out of the hearth, and allowed
to fall into a square shallow iron tray, placed on the ground at the
back of the furnace. For this discharge, the two bricks which serve as
stoppers to that orifice, must be unluted and removed.

As soon as that charge is taken out, (the fire being meanwhile checked
by opening the door T, _fig._ 1034., and shutting partially the ash-pit
opening at A,) a fresh charge must be introduced as above described. The
nearly decomposed saline matter during the second charging of the hearth
I, will have grown cool and concrete. It must be shovelled into the
calcining hearth D, D, _fig._ 1033., by the back door Q, _fig._ 1035.,
where it will receive a higher degree of heat; and, by the expulsion of
the remaining part of the muriatic acid, it will become a perfect
sulphate of soda. It should be finally brought into a state of
semi-fusion. When a sample of it, taken out on the end of the rake or
trowel-shaped scraper, emits no fumes, the conversion is accomplished.

From 3 cwts. of common salt, or muriate of soda, rather more than 3-1/2
cwts. of perfect sulphate should be obtained, quite free from metallic
impurity.

The next step is the conversion of the sulphate into a crude soda.

[Illustration: 1036 1037 1038]

One of the most improved soda furnaces is that, employed in a few
factories, represented in _figs._ 1036, 1037, and 1038. In the section
_fig._ 1037., there are two hearths in one furnace, the one elevated
above the level of the other by the thickness of a brick, or about 3
inches. A is the preparatory shelf, where the mixture to be decomposed
is first laid in order to be thoroughly heated, so that when transferred
to the lower or decomposing hearth B, it may not essentially chill it,
and throw back the operation. C is the fire-bridge, and D is the grate.
In the horizontal section, or ground plan, _fig._ 1038., we see an
opening in the front corresponding to each hearth. This is a door, as
shown in the side view or elevation of the furnace, _fig._ 1036.; and
each door is shut by an iron square frame filled with a fire-tile or
bricks, and suspended by a chain over a pulley fixed in any convenient
place. See PITCOAL, COKING OF, p. 1041. The workman, on pushing up the
door lightly, makes it rise, because there is a counterweight at the
other end of each chain, which balances the weight of the frame and
bricks. In the ground plan, only one smoke-flue is shown; and this
construction is preferred by many manufacturers; but others choose to
have two flues, one from each shoulder, as at _a_, _b_; which two flues
afterwards unite in one vertical chimney, from 25 to 40 feet high;
because the draught of a soda-furnace must be very sharp. Having
sufficiently explained the construction of this improved furnace, I
shall now proceed to describe the mode of making soda with it.

The materials with which the sulphate is decomposed into a rough
carbonate of soda, are chalk or ground limestone, and ground coal or
charcoal. The proportions in which these three substances are mixed,
influence in a remarkable degree the success of the decomposing
process. I have known a false proportion introduced, and persevered in,
at a factory, with the most prejudicial effect to the product; the
soda-ash produced, being in a small quantity relatively to the sulphate
employed, and being much charged with sulphur. After very numerous
trials which I have made on the great scale, and many inquiries at the
most successful soda-works, both in this country and abroad, I am
warranted to offer the following proportions as the most profitable:--

Sulphate of soda, 100 parts: carbonate of lime (chalk or limestone),
from 110 to 120 parts; if pure, 110; if a little impure or damp, 120:
pit coal, 50 parts.

These materials must be separately ground by an edge-stone mill, and
sifted into a tolerably fine powder. They must be then very carefully
mixed. Attention to these particulars is of no little importance to the
success of the soda process.

One hundred parts or pounds of sulphate of soda are equivalent to 75
parts of carbonate, and when skilfully decomposed, will generally yield
fully 70 pounds. A charge for the decomposing furnace with the
preparatory shelf should not exceed 200 lbs., or perhaps 180; therefore
if 75 pounds of ground sulphate of soda, with 80 pounds of chalk or
limestone (ground), and 37 pounds of ground coal; be well mixed, they
will constitute one charge. This charge must be shovelled in upon the
hearth A, or shelf of preparation, (_fig._ 1037.); and whenever it has
become hot (the furnace having been previously brought to bright
ignition), it is to be transferred to the decomposing hearth or
laboratory B, by an iron tool, shaped exactly like an oar, called the
spreader. This tool has the flattened part from 2 to 3 feet long, and
the round part, for laying hold of and working by, from 6 to 7 feet
long. Two other tools are used; one, a rake, bent down like a garden hoe
at the end; and another, a small shovel, consisting of a long iron rod
terminated with a piece of iron plate, about 6 inches long, 4 broad,
sharpened and tipped with steel, for cleaning the bottom of the hearth
from adhering cakes or crusts. Whenever the charge is shoved by the
sliding motion of the oar down upon the working hearth, a fresh charge
should be thrown into the preparation shelf, and evenly spread over its
surface.

The hot and partially carbonized charge being also evenly spread upon
the hearth B, is to be left untouched for about ten minutes, during
which time it becomes ignited, and begins to fuse upon the surface. A
view may be taken of it through a peep-hole in the door, which should be
shut immediately, in order to prevent the reduction of the temperature.
When the mass is seen to be in a state of incipient fusion, the workman
takes the oar and turns it over breadth by breadth in regular layers,
till he has reversed the position of the whole mass, placing on the
surface the particles which were formerly in contact with the hearth.
Having done this, he immediately shuts the door, and lets the whole get
another decomposing heat. After five or six minutes, jets of flame begin
to issue from various parts of the pasty-consistenced mass. Now is the
time to incorporate the materials together, turning and spreading by the
oar, gathering them together by the rake, and then distributing them on
the reverse part of the hearth; that is, the oar should transfer to the
part next the fire-bridge the portion of the mass lying next the shelf,
and _vice versâ_. The dexterous management of this transposition
characterizes a good soda-furnacer. A little practice and instruction
will render this operation easy to a robust clever workman. After this
transposition, incorporation, and spreading, the door may be shut again
for a few minutes, to raise the heat for the finishing off. Lastly, the
rake must be dexterously employed to mix, shift, spread, and
incorporate. The jets, called _candles_, are very numerous, and bright
at first; and whenever they begin to fade, the mass must be raked out
into cast-iron moulds, placed under the door of the laboratory to
receive the ignited paste.

One batch being thus worked off, the other, which has lain undisturbed
on the shelf, is to be shoved down from A to B, and spread equally upon
it, in order to be treated as above described. A third batch is then to
be placed on the shelf.

The article thus obtained should contain at least 22 per cent. of real
soda, equivalent to 37 per cent. of dry carbonate, or to 100 of
crystals. A skilful workman can turn out a batch in from three quarters
of an hour to an hour, producing a perfect carbonate, which yields on
solution an almost colourless liquid, nearly destitute of sulphur, and
containing hardly any decomposed sulphate.

In some soda-works, where the decomposing furnace is very large, and is
charged with a ton of materials at a time, it takes two men to work it,
and from five to six hours to complete a batch. Having superintended the
operation of the above-described small furnace, and examined its
products, I feel warranted to recommend its adoption.

The following materials and products show the average state of this soda
process:--

  _Materials_--100 parts of sulphate of soda, ground, equivalent to 7·5
                   of carbonate; 110 of chalk or ground limestone; 55 of
                   ground coal: in the whole, 265.

  _Products_--168 parts of crude soda, at 33 per cent. = 55·5 of dry
                                                              carbonate.
            { 130    --    crystals of carbonate of soda = 48 of dry
        Or, {              carbonate; and
            { 100    --    insoluble matter.

But these products necessarily vary with the skill of the workman.

In another manufactory the following proportions are used:--Six stones,
of 14 lbs. each, of dry ground sulphate of soda, are mixed with 3 of
chalk and 3 of coal. This mixture, weighing 1-1/2 cwt., forms a batch,
which is spread upon the preparation shelf of the furnace (_figs._ 1037.
and 1038.), as above described, and gradually heated to incipient
ignition. It is then swept forwards to the lower area B, by the iron
oar, and spread evenly by the rake. Whenever it begins to soften under
the rising heat of the laboratory (the side doors being meanwhile shut),
the mass must be laboriously turned over and incorporated; the small
shovel, or paddle, being employed to transfer, by the interchange of
small portions at a time, in rapid but orderly succession, the whole
materials from the colder to the hotter, and from the hotter to the
colder parts of the hearth. The process of working one batch takes about
an hour, during the first half of which period it remains upon the
preparation shelf. The average weight of the finished ball is 1 cwt.,
and its contents in alkalimetrical soda are 33 pounds.

Where the acidulous sulphate of iron from pyrites may be had at a cheap
rate, it has been long ago employed, as at Hurlett in Scotland, instead
of sulphuric acid, for decomposing the chloride of sodium. Mr. Turner’s
process of preparing soda, by decomposing sea salt with litharge and
quicklime, has been long abandoned, the resulting patent yellow, or
sub-chloride of lead, having a very limited sale.

[Illustration: 1039]

2. _The extraction of pure soda from the crude article._--The black
balls must be broken into fragments, and thrown into large square iron
cisterns, furnished with false bottoms of wooden spars; when the
cisterns are nearly full of these lumps, water is pumped in upon them,
till they are all covered. After a few days, the lixiviation is
effected, and the lye is drawn off either by a syphon or by a plug-hole
near the bottom of the cistern, and run into evaporating vessels. These
may be of two kinds. The surface-evaporating furnace, shown in _fig._
1039., is a very admirable invention for economizing vessels, lime, and
fuel. The grate A, and fireplace, are separated from the evaporating
laboratory D, by a double fire-bridge B, C, having an interstitial space
in the middle, to arrest the communication of a melting or igniting heat
towards the lead-lined cistern D. This cistern may be 8, 10, or 20 feet
long, according to the magnitude of the soda-work, and 4 feet or more
wide. Its depth should be about 4 feet. It consists of sheet lead, of
about 6 pounds weight to the square foot, and it is lined with one layer
of bricks, set in roman or hydraulic cement, both along the bottom and
up the sides and ends. The lead comes up to the top of C, and the
liquor, or lye, may be filled in to nearly that height. Things being
thus arranged, a fire is kindled upon the grate A; the flame and hot air
sweep along the surface of the liquor, raise its temperature there
rapidly to the boiling point, and carry off the watery parts in vapour
up the chimney E, which should be 15 or 20 feet high, to command a good
draught. But, indeed, it will be most economical to build one high
capacious chimney stalk, as is now done at Glasgow, Manchester, and
Newcastle, and to lead the flues of the several furnaces above described
into it. In this evaporating furnace the heavier and stronger lye goes
to the bottom, as well as the impurities, where they remain undisturbed.
Whenever the liquor has attained to the density of 1·3, or thereby, it
is pumped up into evaporating cast-iron pans, of a flattened somewhat
hemispherical shape, and evaporated to dryness while being diligently
stirred with an iron rake and iron scraper.

This alkali gets partially carbonated by the above surface-evaporating
furnace, and is an excellent article.

When pure carbonate is wanted, that dry mass must be mixed with its own
bulk of ground coal, sawdust, or charcoal, and thrown into a
reverberatory furnace, like _fig._ 1038., but with the sole all upon one
level. Here it must be exposed to a heat not exceeding 650° or 700° F.;
that is, a little above the melting heat of lead; the only object being
to volatilize the sulphur present in the mass, and carbonate the alkali.
Now, it has been found, that if the heat be raised to distinct redness,
the sulphur will not go off, but will continue in intimate union with
the soda. This process is called calking, and the furnace is called a
calker furnace. It may be six or eight feet long, and four or five feet
broad in the hearth, and requires only one door in its side, with a
hanging iron frame filled with a fire-tile or bricks, as above
described.

This carbonating process may be performed upon several cwts. of the
impure soda, mixed with sawdust, at a time. It takes three or four hours
to finish the desulphuration; and it must be carefully turned over by
the oar and the rake, in order to burn the coal into carbonic acid, and
to present the carbonic acid to the particles of caustic soda diffused
through the mass, so that it may combine with them.

When the blue flames cease, and the saline matters become white, in the
midst of the coaly matter, the batch may be considered as completed. It
is raked out, and when cooled, lixiviated in great iron cisterns with
false bottoms, covered with mats. The watery solution being drawn off
clear by a plug-hole, is evaporated either to dryness, in hemispherical
cast-iron pans, as above described, or only to such a strength that it
shows a pellicle upon its surface, when it may be run off into
crystallizing cisterns of cast iron, or lead-lined wooden cisterns. The
above dry carbonate is the best article for the glass manufacture.

_Crystallized carbonate of soda_, contains 62-3/4 per cent. of water.
The crystals are colourless transparent rhomboids, which readily
effloresce in the air, and melt in their own water of crystallization.
On decanting the liquid from the fused mass, it is found that one part
of the salt has given up its water of crystallization to another. By
evaporation of that fluid, crystals containing one-fifth less water than
the common carbonate are obtained. These do not effloresce in the air.

_Mineral soda_, the sesquicarbonate, (_Anderthalb kohlensaures natron_,
Germ.); is found in the province of Sukena, in Africa, between Tripoli
and Fezzan. It forms a stratum no more than an inch thick, just below
the surface of the soil. Its texture is striated crystalline, like
fibrous gypsum. Several hundred tons of it are collected annually, which
are chiefly consumed in Africa. This species of soda does not effloresce
like the Egyptian, or the manufactured soda crystals, owing to its
peculiar state of composition and density. It was analyzed by Klaproth,
under its native name of _trona_, and was found to consist, in 100
parts, of--soda, 37; carbonic acid, 38; sulphate of soda, 2·5; water,
22·5, in 100.

This soda is, therefore, composed of--3 atoms of carbonic acid,
associated with 2 atoms of soda, and 4 of water; while our commercial
soda crystals are composed of--1 atom of carbonic acid, 1 atom of soda,
and 10 atoms of water.

There are six natron lakes in Egypt. They are situated in a barren
valley, called Bahr-bela-ma, about thirty miles to the west of the
Delta.

There are natron lakes also in Hungary, which afford in summer a white
saline efflorescent crust of carbonate of soda, mixed with a little
sulphate.

There are several soda lakes in Mexico, especially to the north of
Zacatecas, as also in many other provinces. In Columbia, 48 English
miles from Merida, mineral soda is extracted from the earth in great
abundance, under the name of _urao_.

_Bicarbonate of soda_ (_Doppelt kohlensaures natron_, Germ.); is
prepared, like bicarbonate of potassa, by transmitting carbonic acid gas
through a cold saturated solution of pure carbonate of soda, till
crystalline crusts be formed. The bicarbonate may also be obtained in
four-sided tables grouped together. It has an alkaline taste and
reaction upon litmus paper, dissolves in 13 parts of cold water, and is
converted by boiling water into the sesquicarbonate, with the
disengagement of one fourth of its carbonic acid. It consists of--37 of
soda, 52·35 carbonic acid, and 10·65 water.


SODA-WATER, is the name given to water containing a minute quantity of
soda, and highly charged with carbonic acid gas, whereby it acquires a
sparkling appearance, an agreeable pungent taste, an exhilarating
quality, and certain medicinal powers. It constitutes a considerable
object of manufacture in this kingdom. The following figure represents,
I understand, the best system of apparatus for preparing it. A very
dilute solution of soda is put into the globular vessel H, and the
carbonic acid gas is forced into it from the gasometer E, by means of
the powerful pump-work, as will be understood from the subjoined
explanation.

The same apparatus may serve for making any species of aerated water, in
imitation of any natural spring. All that is necessary for this purpose,
is to put into the cistern Q, the neutro-saline matter, earths, metallic
oxides, pure water, &c., each in due proportion, according to the most
accredited analysis of the mineral water to be imitated, to agitate that
mixture, to suck it into the condenser H, through the pipe R, and then
to impregnate it to the due degree, by pumping in the appropriate gas,
previously contained in the gasometer F.

Thus, to make Seltzer water, for each 12 pounds troy, = 69,120 grains,
or 1 gallon imperial very nearly, take 55 grains of dry carbonate of
soda, 17 of carbonate of lime, 18 of carbonate of magnesia, 3-1/2 of
subphosphate of alumina, 3 of chloride of potassium, 155 of chloride of
sodium, and 3 of finely precipitated silica. Put these materials into
the cistern Q, and charge the gasometer F with 353 cubic inches of
carbonic acid gas. Then work the machine by the handle of the wheel X,
as explained below, and regulate the introduction of the liquid and the
gas in aliquot portions; for example, if the condenser H admits half a
gallon of water at a time, that quantity of liquid should be charged
with 176 cubic inches of the gas, being one half of the whole quantity.
The sulphuretted mineral waters may be imitated in like manner, by
taking the proportions of their constituents, as given in Table II. of
WATERS, MINERAL.

IMPROVED SODA-WATER APPARATUS, AS MADE BY MR. HAYWARD TYLER, OF MILTON
STREET.

_Fig._ 1040. front view of the soda-water machine. _Fig._ 1041. end view
of the same.

[Illustration: 1040 1041]

A, lead generator, for making the gas. B, lead pot, for holding
sulphuric acid. C, handle for moving the agitator of the receiver, which
stirs up the ingredients in the lead generator. _a_, cap and screw, for
charging the lead pot with sulphuric acid. _b_, swivel-joint, which is
movable, for occasionally throwing in portions of sulphuric acid for
generating gas. _c_, stuffing-box for agitator. _d_, large cap and
screw, for charging the lead generator with whiting and water. _e_, cap
and screw, for emptying contents of ditto. D, lead pipe, to convey the
gas from the lead generator to gasometer. E, wood tub, filled with
water, for gasometer to work in. F, copper gasometer. G, strong iron
frame, for gasometer and tub to stand on, firmly fixed together by three
wrought-iron rods, _f_, _f_. _g_, _g_, two pulleys, for carrying rope
and counterbalance weight _h_, for balancing copper gasometer. _i_, cock
for discharging atmospheric air contained in the gasometer before making
the gas. _k_, cock for occasionally emptying the water out of the tub.
_l_, union joint, to which is fixed a copper pipe, passing through the
water in the tub, to deliver the gas as generated into the copper
gasometer. _m_, another union joint, with a similar copper pipe, passing
through the water in the tub, and projecting two or three inches above
the surface of the water, to convey the gas from the copper gasometer to
the soda-water machine. H, H, condenser for aerating the soda-water. I,
safety valve. K, K, bottling valve. L, bottling nipple. M, M, soda-water
pump. N, valve-piece. O, O, piston of the pump. P, pipe for conducting
gas from the gasometer to pump. Q, copper pan for holding the solution
of soda. R, copper pipe for conducting the solution of soda to the force
pump. S, S, two cocks for regulating the admission of the solution and
gas to the pump. T, copper pipe through which the soda-water is forced
to the condenser. U, pinion wheel, to give motion to the agitator
revolving inside the condenser. V, V, wheel for driving ditto. W, W,
cast-iron frame for carrying machinery. X, X, cast-iron fly-wheel. Z,
wrought-iron crank. Y, Z, Z, wood stools and curb, upon which the whole
of the machinery is fixed.


SODIUM, the metallic basis of soda, is obtained by processes similar to
those by which potassium is procured. By fusing hydrate of soda with a
little hydrate of potassa, a mixture is obtained, which yields more
readily than soda by itself to the decomposing action of iron-turnings
at a high heat, in a bent gun-barrel. The portion of potassium produced,
may be got rid of, by digesting the alloy for a few days in some naphtha
or oil of turpentine contained in an open vessel. The sodium remains at
the bottom of the liquid. Pure sodium may, however, be prepared at once,
by subjecting incinerated tartrate of soda to heat in the apparatus of
Brunner, described under POTASSIUM. It is white, like silver; softer and
more malleable than any other metal, and may be readily reduced into
very thin leaves. It preserves its malleability till it approaches the
melting point. Its specific gravity is 0·970. It softens at the
temperature of 122° F., and at 200° it is perfectly fluid; but it will
not rise in vapour until heated to nearly the melting point of glass. In
the air it oxidizes slowly, and gets covered with a crust of soda; but
it does not take fire till it is made nearly red-hot; and then it emits
brilliant scintillations. When thrown upon water, it is rapidly
oxidized, but without kindling, like potassium. If a drop of water be
thrown upon it, it becomes so hot by the chemical action as to take
fire. There are three oxides of sodium; 1. the suboxide; 2. the oxide,
or the basis of common soda; and, 3. the suroxide; the last being formed
when sodium is heated to redness upon a plate of silver.


SOLDERING (_Souder_, Fr.; _Löthen_, Germ.); is the process of uniting
the surfaces of metals, by the intervention of a more fusible metal,
which being melted upon each surface, serves, partly by chemical
attraction, and partly by cohesive force, to bind them together. The
metals thus united may be either the same or dissimilar; but the uniting
metal must always have an affinity for both. Solders must be, therefore,
selected in reference to their appropriate metals. Thus tin-plates are
soldered with an alloy consisting of from 1 to 2 parts of tin, with 1 of
lead; pewter is soldered with a more fusible alloy, containing a certain
proportion of bismuth added to the lead and tin; iron, copper, and brass
are soldered with spelter, an alloy of zinc and copper, in nearly equal
parts; silver, sometimes with pure tin, but generally with
silver-solder, an alloy consisting of 5 parts of silver, 6 of brass, and
2 of zinc; zinc and lead, with an alloy of from 1 to 2 parts of lead
with 1 of tin; platinum, with fine gold; gold, with an alloy of silver
and gold, or of copper and gold; &c.

In all soldering processes, the following conditions must be observed:
1. the surfaces to be united must be entirely free from oxide, bright,
smooth, and level; 2. the contact of air must be excluded during the
soldering, because it is apt to oxidize one or other of the surfaces,
and thus to prevent the formation of an alloy at the points of union.
This exclusion of air is effected in various ways. The locksmith encases
in loam the objects of iron, or brass, that he wishes to subject to a
soldering heat; the silversmith and brazier mix their respective solders
with moistened borax powder; the coppersmith and tinman apply sal
ammoniac, rosin, or both, to the cleaned metallic surfaces, before using
the soldering-iron to fuse them together with the tin alloy. The strong
solder of the coppersmith consists of 8 parts of brass and 1 of zinc;
the latter being added to the former, previously brought into a state of
fusion. The crucible must be immediately covered up for two minutes till
the combination be completed. The melted alloy is to be then poured out
upon a bundle of twigs held over a tub of water, into which it falls in
granulations. An alloy of 3 parts of copper and 1 of zinc forms a still
stronger solder for the coppersmiths. When several parts are to be
soldered successively upon the same piece, the more fusible alloys,
containing more zinc, should be used first. A softer solder for
coppersmiths is made with 6 parts of brass, 1 of tin, and 1 of zinc; the
tin being first added to the melted brass, then the zinc; and the whole
well incorporated by stirring.

The edges of sheet lead for sulphuric acid chambers, and its
concentration pans, are joined together by melted lead itself, because
any solder containing tin would soon be corroded. With this view, the
two edges being placed in contact, are flattened down into a long wooden
groove, and secured in their situation by a few brass pins driven into
the wood. The surfaces are next brightened with a triangular scraper,
rubbed over with candle grease, and then covered with a stream of hot
melted lead. The riband of lead thus applied is finally equalized by
being brought into partial fusion with the plumber’s conical iron heated
to redness; the contact of air being prevented by sprinkling rosin over
the surface. The sheets of lead are thus _burned_ together, in the
language of the workmen.


SOOT (_Noir de fumée_, _Suie_, Fr.; _Rus_, _Flatterrus_, Germ.); is the
pulverulent charcoal condensed from the smoke of wood or coal fuel. A
watery infusion of the former is said to be antiseptic, probably from
its containing some creosote.

The soot of pitcoal has not been analyzed with any minuteness. It
contains some sulphate and carbonate of ammonia, along with bituminous
matter.


SORBIC ACID, is the same with malic acid; which see.


SOY, is a liquid condiment, or sauce, imported chiefly from China. It is
prepared with a species of white haricots, wheat flour, common salt, and
water; in the proportions respectively of 50, 60, 50, and 250 pounds.
The haricots are washed, and boiled in water till they become so soft as
to yield to the fingers. They are then laid in a flat dish to cool, and
kneaded along with the flour, a little of the hot water of the decoction
being added from time to time. This dough is next spread an inch or an
inch and a half thick upon the flat vessel (made of thin staves of
bamboo), and when it becomes hot and mouldy, in two or three days, the
cover is raised upon bits of stick, to give free access of air. If a
rancid odour is exhaled, and the mass grows green, the process goes on
well; but if it grows black, it must be more freely exposed to the air.
As soon as all the surface is covered with green mouldiness, which
usually happens in eight or ten days, the cover is removed, and the
matter is placed in the sunshine for several days. When it has become as
hard as a stone, it is cut into small fragments, thrown into an earthen
vessel, and covered with the 250 pounds of water having the salt
dissolved in it. The whole is stirred together, and the height at which
the water stands is noted. The vessel being placed in the sun, its
contents are stirred up every morning and evening; and a cover is
applied at night, to keep it warm and exclude rain. The more powerful
the sun, the sooner the soy will be completed; but it generally requires
two or three of the hottest summer months. As the mass diminishes by
evaporation, well water is added; and the digestion is continued till
the salt water has dissolved the whole of the flour and the haricots;
after which the vessel is left in the sun for a few days, as the good
quality of the soy depends on the completeness of the solution, which is
promoted by regular stirring. When it has at length assumed an oily
appearance, it is poured into bags, and strained. The clear black liquid
is the soy, ready for use. It is not boiled, but is put up into bottles,
which must be carefully corked. Genuine soy was made in this way at
Canton, by Michael de Grubbens. See _Memoirs of Academy of Sciences of
Stockholm_ for 1803.


SPECIFIC GRAVITY, designates the relative weights of different bodies
under the same bulk; thus a cubic foot of water weighs 1000 ounces
avoirdupois; a cubic foot of coal, 1350; a cubic foot of cast iron,
7280; a cubic foot of silver, 10,400; and a cubic foot of pure gold,
19,200; numbers which represent the specific gravities of the respective
substances, compared to water = 1·000. See ALLOY.


SPECULUM METAL, is an alloy of copper and tin; described under COPPER.


SPERMACETI; the _Cetine_ of Chevreul. In certain species of the
_cachalot_ whale, as the _Physeter macrocephalus_, _tursio_, _microps_,
and _orthodon_, as also the _Delphinus edentulus_, the fat of some parts
of their bodies contains a peculiar kind of stearine, called spermaceti.
The oil obtained from cavities in the bones of the cranium of the above
cetaceæ is the richest in this kind of stearine. This being thrown into
great filter-bags, the spermaceti oil passes through, and is
subsequently purified by the addition of a small quantity of potash lye,
which precipitates certain matters by neutralizing the acid that held
them in solution. The solid which remains on the filter is next squeezed
in bags, by means of a horizontal hydraulic press encased in steam, then
digested with a weak potash lye, in order to dissolve out any oil which
may continue to adhere to it, washed with water, finally dissolved in a
tub by the agency of steam, laded into tin pans, and allowed slowly to
concrete into a white semi-transparent brittle lamellar crystalline
mass, which forms elegant candles.

At 60° its specific gravity is 0·943. It melts at 112·5°; 100 parts of
alcohol at 0·821 dissolve 3-1/2 of it, of which 0·9 are deposited on
cooling. Warm ether dissolves it in very large quantities. It is soluble
also in the fat of volatile oils; and if the solutions have been
saturated while hot, the greater part of the spermaceti crystallizes on
cooling. When this substance has been purified by digesting alcohol upon
it repeatedly, what remains is the _cetine_ of Chevreul, or pure
spermaceti. Its melting point has now become 116° F., and its boiling
point 616° F., at which it distils without alteration. Caustic alkaline
lyes saponify it with difficulty.


SPIRIT OF AMMONIA, is, properly speaking, alcohol combined with ammonia
gas; but the term is often applied to water of ammonia.


SPIRITS, VINOUS. This subject has been fully discussed in the articles
ALCOHOL, DISTILLATION, and FERMENTATION. I have shown that the
progressive increase of alcohol in the wash tends progressively to
prevent the conversion of the wort into spirit, or checks the fermenting
process, though a great deal of fermentable matter remains unchanged.
Mr. Sheridan has sought to remove this obstacle to the thorough
transmutation of saccharine matter into alcohol, by drawing off the
spirit as it is formed. For this purpose he ferments his wash in close
tuns, connected with a powerful air-pump worked by machinery, thus
continually removing the carbonic acid as it is formed, and maintaining
a diminished pressure under which the alcohol readily distils at a
temperature of 120° or 130° F. He finds that this degree of heat is not
injurious to the fermentation, provided that it be communicated by the
air of a stove-room, and not by water or steam pipes traversing the
liquid, which would inevitably scald or seeth the particles in
succession, and thereby extinguish the fermenting principle.

By the above ingenious plan, Mr. Sheridan tells me he has obtained 28
gallons of proof spirit from a quarter of grain, instead of the average
product 21, being an increase of 25 per cent. The experiment was tried
upon a considerable scale at Messrs. Currie’s great distillery near
London; but could not be established as a mode of manufacture, on
account of the excise laws, which prohibit the distillers from carrying
on the two processes of fermentation and distillation at the same time.


SPIRIT OF WINE; Alcohol.


SPONGE (_Eponge_, Fr.; _Schwamm_, Germ.); is a cellular fibrous tissue
produced by small animals, almost imperceptible, called polypi by
naturalists, which live in the sea. This tissue is said to be covered in
its recent state with a kind of semi-fluid thin coat of animal jelly,
susceptible of a slight contraction or trembling on being touched; which
is the only symptom of vitality displayed by the sponge. After death,
this jelly disappears, and leaves merely the sponge; formed by the
combination of a multitude of small capillary tubes, capable of
receiving water in their interior, and of becoming thereby distended.
Sponges occur attached to stones at the bottom of the sea; and abound
particularly upon the shores of the islands in the Grecian Archipelago.
Although analogous in their origin to coral, sponges are quite different
in their nature; the former being composed almost entirely of carbonate
of lime; while the latter are formed of the same elements as animal
matters, and afford, on distillation, a considerable quantity of
ammonia.

Dilute sulphuric acid has been recommended for bleaching sponges, after
the calcareous impurities have been removed by muriatic acid. Chlorine
water answers better.


SPOON MANUFACTURE. See STAMPING OF METALS.


STAINED GLASS. When certain metallic oxides or chlorides, ground up with
proper fluxes, are painted upon glass, their colours fuse into its
surface at a moderate heat, and make durable pictures, which are
frequently employed in ornamenting the windows of churches as well as of
other public and private buildings. The colours of stained glass are all
transparent, and are therefore to be viewed only by transmitted light.
Many metallic pigments, which afford a fine effect when applied cold on
canvas or paper, are so changed by vitreous fusion as to be quite
inapplicable to painting in stained glass.

The glass proper for receiving these vitrifying pigments, should be
colourless, uniform, and difficult of fusion; for which reason crown
glass, made with little alkali, or with kelp, is preferred. When the
design is too large to be contained on a single pane, several are fitted
together, and fixed in a bed of soft cement while painting, and then
taken asunder to be separately subjected to the fire. In arranging the
glass pieces, care must be taken to distribute the joinings so that the
lead frame-work may interfere as little as possible with the effect.

A design must be drawn upon paper, and placed beneath the plate of
glass; though the artist cannot regulate his tints directly by his
pallet, but by specimens of the colours producible from his pallet
pigments after they are fired. The upper side of the glass being sponged
over with gum-water, affords, when dry, a surface proper for receiving
the colours, without the risk of their running irregularly, as they
would be apt to do, on the slippery glass. The artist first draws on the
plate, with a fine pencil, all the traces which mark the great outlines
and shades of the figures. This is usually done in black, or, at least,
some strong colour, such as brown, blue, green, or red. In laying on
these, the painter is guided by the same principles as the engraver,
when he produces the effect of light and shade by dots, lines, or
hatches; and he employs that colour to produce the shades, which will
harmonize best with the colour which is to be afterwards applied; but
for the deeper shades, black is in general used. When this is finished,
the whole picture will be represented in lines or hatches similar to an
engraving finished up to the highest effect possible; and afterwards,
when it is dry, the vitrifying colours are laid on by means of larger
hair pencils; their selection being regulated by the burnt specimen
tints. When he finds it necessary to lay two colours adjoining, which
are apt to run together in the kiln, he must apply one of them to the
back of the glass. But the few principal colours to be presently
mentioned, are all fast colours, which do not run, except the yellow,
which must therefore be laid on the opposite side. After colouring, the
artist proceeds to bring out the lighter effects by taking off the
colour in the proper place, with a goose quill cut like a pen without a
slit. By working this upon the glass, he removes the colour from the
parts where the lights should be the strongest; such as the hair, eyes,
the reflection of bright surfaces and light parts of draperies. The
blank pen may be employed either to make the lights by lines, or hatches
and dots, as is most suitable to the subject.

By the metallic preparations now laid upon it, the glass is made ready
for being fired, in order to fix and bring out the proper colours. The
furnace or kiln best adapted for this purpose, is similar to that used
by enamellers. See ENAMEL, and the _Glaze-kiln_; under POTTERY. It
consists of a muffle or arch of fire-clay or pottery, so set over a
fireplace, and so surrounded by flues, as to receive a very considerable
heat within, in the most equable and regular manner; otherwise some
parts of the glass will be melted; while, on others, the superficial
film of colours will remain unvitrified. The mouth of the muffle, and
the entry for introducing fuel to the fire, should be on opposite sides,
to prevent as much as possible the admission of dust into the muffle,
whose mouth should be closed with double folding-doors of iron,
furnished with small peep-holes, to allow the artist to watch the
progress of the staining, and to withdraw small trial slips of glass,
painted with the principal tints used in the picture.

The muffle must be made of very refractory fire-clay, flat at its
bottom, and only 5 or 6 inches high, with such an arched top as may make
the roof strong, and so close on all sides as to exclude entirely the
smoke and flame. On the bottom of the muffle a smooth bed of sifted
lime, freed from water, about half an inch thick, must be prepared for
receiving the pane of glass. Sometimes several plates of glass are laid
over each other with a layer of dry pulverulent lime between each. The
fire is now lighted, and most gradually raised, lest the glass should be
broken; and after it has attained to its full heat, it must be kept up
for 3 or 4 hours, more or less, according to the indications of the
trial slips; the yellow colour being principally watched, as it is found
to be the best criterion of the state of the others. When the colours
are properly burnt in, the fire is suffered to die away, so as to anneal
the glass.

STAINED-GLASS PIGMENTS.

_Flesh colour._--Take an ounce of red lead, two ounces of red enamel
(Venetian glass enamel, from alum and copperas calcined together), grind
them to fine powder, and work this up with spirits (alcohol) upon a hard
stone. When slightly baked, this produces a fine flesh colour.

_Black colour._--Take 14-1/2 ounces of smithy scales of iron, mix them
with two ounces of white glass (crystal), an ounce of antimony, and half
an ounce of manganese; pound and grind these ingredients together with
strong vinegar. A brilliant black may also be obtained by a mixture of
cobalt blue with the oxides of manganese and iron. Another black is made
from three parts of crystal glass, two parts of oxide of copper, and one
of (glass of) antimony worked up together, as above.

_Brown colour._--An ounce of white glass or enamel, half an ounce of
good manganese; ground together.

_Red, rose, and brown colours_, are made from peroxide of iron, prepared
by nitric acid. The flux consists of borax, sand, and minium in small
quantity.

_Red colour_, may be likewise obtained from one ounce of red chalk
pounded, mixed with two ounces of white hard enamel, and a little
peroxide of copper.

_A red_, may also be composed of rust of iron, glass of antimony, yellow
glass of lead, such as is used by potters (or litharge), each in equal
quantity; to which a little sulphuret of silver is added. This
composition, well ground, produces a very fine red colour on glass. When
protoxide of copper is used to stain glass, it assumes a bright red or
green colour, according as the glass is more or less heated in the
furnace, the former corresponding to the orange protoxide, the latter
having the copper in the state of peroxide.

_Bistres and brown reds_, may be obtained by mixtures of manganese,
orange oxide of copper, and the oxide of iron called umber, in different
proportions. They must be previously fused with vitreous solvents.

_Green colour._--Two ounces of brass calcined into an oxide, two ounces
of minium, and eight ounces of white sand; reduce them to a fine powder,
which is to be enclosed in a well luted crucible, and heated strongly in
an air-furnace for an hour. When the mixture is cold, grind it in a
brass mortar. Green may, however, be advantageously produced by a yellow
on one side, and a blue on the other. Oxide of chrome has been also
employed to stain glass green.

_A fine yellow colour._--Take fine silver laminated thin, dissolve in
nitric acid, dilute with abundance of water, and precipitate with
solution of sea salt. Mix this chloride of silver, in a dry powder, with
three times its weight of pipe-clay well burnt and pounded. The back of
the glass pane is to be painted with this powder; for when painted on
the face, it is apt to run into the other colours.

_Another yellow_ can be made by mixing sulphuret of silver with glass of
antimony, and yellow ochre previously calcined to a red-brown tint. Work
all these powders together, and paint on the back of the glass. Or
silver _laminæ_ melted with sulphur, and glass of antimony, thrown into
cold water, and afterwards ground to powder, afford a yellow.

_A pale yellow_ may be made with the powder resulting from brass,
sulphur, and glass of antimony, calcined together in a crucible, till
they cease to smoke; and then mixed with a little burnt yellow ochre.

_The fine yellow_ of M. Merand, is prepared from chloride of silver,
oxide of zinc, white-clay, and rust of iron. This mixture, simply
ground, is applied on the glass.

_Orange colour._--Take 1 part of silver powder, as precipitated from the
nitrate of that metal by plates of copper, and washed; mix it with 1
part of red ochre and 1 of yellow, by careful trituration; grind into a
thin pap with oil of turpentine or lavender, and apply this with a
brush, dry, and burn in.

In the Philosophical Magazine, of December, 1836, the anonymous author
of an ingenious essay, “On the Art of Glass-painting,” says, that if a
large proportion of ochre has been employed with the silver, the stain
is yellow; if a small proportion, it is orange-coloured; and by repeated
exposure to the fire, without any additional colouring-matter, the
orange may be converted into red; but this conversion requires a nice
management of the heat. Artists often make use of panes coloured
throughout their substance in the glass-house pots, because the perfect
transparency of such glass gives a brilliancy of effect, which enamel
painting, always more or less opaque, cannot rival. It was to a glass of
this kind that the old glass-painters owed their splendid red. This is,
in fact, the only point in which the modern and antient processes
differ; and this is the only part of the art which was ever really lost.
Instead of blowing plates of solid red, the old glass-makers (like those
of Bohemia, for some time back,) used to _flash_ a thin layer of
brilliant red over a substratum of colourless glass; by gathering a lump
of the latter upon the end of their iron rod in one pot, covering it
with a layer of the former in another pot, then blowing out the two
together into a globe or cylinder, to be opened into circular tables, or
into rectangular plates. The elegant art of tinging glass red by
protoxide of copper, and flashing it on common crown glass, has become
general within these few years.

That gold melted with flint glass stains it purple, was originally
discovered and practised, as a profitable secret, by Kunckel. Gold has
been recently used at Birmingham for giving a beautiful rose-colour to
scent bottles. The proportion of gold should be very small, and the heat
very great, to produce a good effect. The glass must contain either the
oxide of lead, bismuth, zinc, or antimony; for crown glass will take no
colour from gold. Glass combined with this metal, when removed from the
crucible is generally of a pale rose-colour; nay, sometimes is as
colourless as water, and does not assume its ruby colour till it has
been exposed to a low red heat, either under a muffle or at the lamp.
This operation must be nicely regulated; because a slight excess of fire
destroys the colour, leaving the glass of a dingy brown, but with a blue
(green?) transparency, like that of gold leaf. It is metallic gold which
gives the colour; and, indeed, the oxide is too easily reduced, not to
be converted into the metal by the intense heat which is necessarily
required.

Upon the kindred art of painting in enamel, Mr. A. Essex has published
an interesting paper in the same journal, for June, 1837, in which he
says that the antient ruby glass, on being exposed to the heat of a
glass-kiln, preserves its colour unimpaired, while the modern suffers
considerable injury, and in some cases becomes almost black. Hence the
latter cannot be painted upon, as the heat required to fix the fresh
colour would destroy the beauty of the original basis. To obviate this
difficulty, the artist paints upon a piece of plain glass the tints and
shadows necessary for blending the rich ruby glow with the other parts
of his picture, leaving those parts untouched where he wishes the ruby
to appear in undiminished brilliancy, and fixes the ruby glass in the
picture behind the painted piece, so that in such parts, the window is
double-glazed. Mr. Essex employs, as did the late Mr. Muss, chrome oxide
alone for greens; and he rejects the use of iron and manganese in his
enamel colours.

Coloured transparent glass is applied as enamel in silver and gold
_bijouterie_, previously _bright-cut_ in the metal with the graver or
the rose-engine. The cuts, reflecting the rays of light from their
numerous surfaces, exhibit through the glass, richly stained with gold,
silver, copper, cobalt, &c., a gorgeous play of prismatic colours,
varied with every change of aspect. When the enamel is to be painted on,
it should be made opalescent by oxide of arsenic, in order to produce
the most agreeable effect.

The artist in enamel has obtained from modern chemistry, preparations of
the metals platinum, uranium, and chromium, which furnish four of the
richest and most useful colours of his palette. Oxide of platinum
produces a substantive rich brown, formerly unknown in enamel painting;
a beautiful transparent tint, which no intensity or repetition of firing
can injure. Colours proper for enamel painting, he says, are not to be
purchased; those sold for the purpose, are adapted only for painting
upon china. The constituents of the green enamel used by his brother,
Mr. W. Essex, are, silica, borax, oxide of lead, and oxide of chrome.

Mr. Essex’s enamelling furnace is a cubic space of about 12 inches, and
contains a fire-clay muffle, without either bottom or back, which is
surrounded with coke, except in front. The entire draught of air which
supplies the furnace, passes through the muffle; the plates and
paintings being placed on a thin slab, made of tempered fire-clay,
technically termed _planche_, which rests on the bed of coke-fuel. As
the greatest heat is at the back of the muffle, the picture must be
turned round while in the fire, by means of a pair of spring tongs. The
above furnace serves for objects up to five inches in diameter; but for
larger works a different furnace is required, for the description of
which I must refer to the original paper.

Relatively to the receipts for enamel colours, and for staining and
gilding on glass, for which twenty guineas were voted by the Society for
the Encouragement of Arts, in the session of 1817, to Mr. R. Wynn, Mr.
A. Essex says, in p. 446. of his essay--“the unfortunate artist who
shall attempt to make colours for the purpose of painting in enamel from
these receipts, will assuredly find, to his disappointment, that they
are utterly useless.” In page 449. he institutes a comparison between
Mr. Wynn’s complex _farrago_ for green, as published in the Transactions
of the Society, with the simple receipt of his brother, as given above.
It is a remarkable circumstance, that not one of our enamel artists,
during a period of twenty years, should have denounced the fallacy of
these receipts, and the folly of sanctioning imposture by a public
reward. Should Mr. Essex’s animadversions be just, the well-intentioned
Society in the Adelphi may, from the negligence of its committee, come
to merit the _sobriquet_, “For the Discouragement of Arts.”


STAMPING OF METALS. The following ingenious machine for manufacturing
metal spoons, forks, and other articles, was made the subject of a
patent by Jonathan Hayne, of Clerkenwell, in May, 1833. He employs a
stamping-machine with dies, in which the hammer is raised to a height
between guides, and is let fall by a trigger. He prefers fixing the
protuberant or relief portion of the die to the stationary block or bed
of the stamping-machine, and the counterpart or intaglio to the falling
hammer or ram.

The peculiar feature of improvement in this manufacture consists in
producing the spoon, ladle, or fork perfect at one blow in the
stamping-machine, and requiring no further manipulation of shaping, but
simply trimming off the barb or fin, and polishing the surface, to
render the article perfect and finished.

Heretofore, in employing a stamping-machine, or fly-press, for
manufacturing spoons, ladles, and forks, it has been the practice to
give the impressions to the handles, and to the bowls or prongs, by
distinct operations of different dies, and after having so partially
produced the pattern upon the article, the handles had to be bent and
formed by the operations of filing and hammering.

By his improved form of dies, which, having curved surfaces and bevelled
edges, allow of no parts of the faces of the die and counter-die to come
into contact, he is enabled to produce considerable elevations of
pattern and form, and to bring up the article perfect at one blow, with
only a slight barb or fin upon its edge.

[Illustration: 1042 1043 1044]

In the accompanying drawings, _fig._ 1042. is the lower or bed die for
producing a spoon, seen edgewise; _fig._ 1043. is the face of the upper
or counter-die, corresponding; _fig._ 1044. is a section, taken through
the middle of the pair of dies, showing the space in which the metal is
pressed to form the spoon.

To manufacture spoons, ladles, or forks according to his improved
process, he first forges out the ingot into flat pieces, of the shape
and dimensions of the die of the intended article; and if a spoon or
ladle is to be made, gives a slight degree of concavity to the bowl
part; but, if necessary, bends the back, in order that it may lie more
steadily, and bend more accurately, upon the lower die; if a fork, he
cuts or otherwise removes portions of the metal at those parts which
will intervene between the prongs; and, having thus produced the rude
embryo of the intended article, scrapes its entire surface clean and
free from oxidation-scale or fire-strain, when it is ready to be
introduced into the stamping-machine.

[Illustration: 1045 1046]

He now fixes the lower die in the bed of the stamping-machine, shown at
_a_, _a_, in the elevations _figs._ 1045. and 1046., and fixes, in the
hammer _b_, the upper or counter-die _c_, accurately adjusting them
both, so that they may correspond exactly when brought together. He then
places the rudely-formed article above described upon the lower die, and
having drawn up the hammer to a sufficient elevation by a windlass and
rope, or other ordinary means, lets go the trigger, and allows the
hammer with the counter-die to fall upon the under die, on which the
article is placed; when, by the blow thus given to the metal, the true
and perfect figure and pattern of the spoon, ladle, or fork is produced,
and which, as before said, will only require the removal of the slight
edging of barb or fin, with polishing, to finish it.

On striking the blow, in the operation of stamping the article, the
hammer will recoil and fly up some distance, and if allowed to fall
again with reiterated blows, would injure both the article and the dies;
therefore, to avoid this inconvenience, he causes the hammer on
recoiling to be caught by a pair of palls locking into racks on the face
of the standards, seen in _figs._ 1045. and 1046. In _fig._ 1045. the
hammer _b_, of the stamping-machine, is seen raised and suspended by a
rope attached to a pair of jointed hooks or holders _d_, _d_, the lower
ends of which pass into eyes _e_, _e_, extending from the top of the
hammer. When the lever or trigger _t_ is drawn forward, as in _fig._
1046., the two inclined planes _g_, _g_, on the axle _h_, press the two
legs of the holders _d_, _d_, inward, and cause their hooks or lower
ends to be withdrawn from the eyes _e_, _e_, when the hammer instantly
falls, and brings the dies together: such is the ordinary construction
of the stamping-machine.

On the hammer falling from a considerable elevation, the violence of the
blow causes it to recoil and bound upwards, as before mentioned; it
therefore becomes necessary to catch the hammer when it has rebounded,
in order to prevent the dies coming again together; this is done by the
following mechanism:--

Two latch levers _i_, _i_, are connected by joints to the upper part of
the hammer, and two pall levers _k_, _k_, turning upon pins, are mounted
in the bridge _l_, affixed to the hammer. Two springs _m_, _m_, act
against the lower arms of these levers, and press them outwards, for the
purpose of throwing the palls at the lower ends of the levers into the
teeth of the ratchet racks _n_, _n_, fixed on the sides of the upright
standards.

Previously to raising the hammer, the upper ends of the pall levers _k_,
are drawn back, and the latches _i_, being brought down upon them, as in
_fig._ 1045., the levers _k_ are confined, and their palls prevented
from striking into the side racks; but as the hammer falls, the ends of
the latches _i_ strike upon the fingers _o_, _o_, fixed to the side
standards, and liberate the palls, the lower ends of which, when the
hammer rebounds, after stamping, catch into the teeth of the racks, as
in _fig._ 1046., and thereby prevent the hammer from again descending.


STARCH; (_Amidon_, _Fecule_, Fr.; _Stärke_, Germ.); is a white
pulverulent substance, composed of microscopic spheroids, which are bags
containing the amylaceous matter. It exists in a great many different
plants, and varies merely in the form and size of its microscopic
particles; as found in some plants, it consists of spherical particles
1/1000 of an inch in diameter; and in others, of ovoid particles, of
1/300 or 1/400 of an inch. It occurs, 1. in the seeds of all the
acotyledinous plants, among which are the several species of corns, and
those of other _gramineæ_; 2. in the round perennial tap roots, which
shoot up an annual stem; in the tuberose roots, such as potatos, the
_Convolvulus batatas_ and _edulis_, the _Helianthus tuberosus_, the
_Jatropha manihot_, &c., which contain a great quantity of it; 3. in the
stems of several monocotyledinous plants, especially of the palm tribe,
whence sago comes; but it is very rarely found in the stems and branches
of the dicotyledinous plants; 4. it occurs in many species of lichen.
Three kinds of starch have been distinguished by chemists; that of
wheat, that called _inuline_, and lichen starch. These three agree in
being insoluble in cold water, alcohol, ether, and oils, and in being
converted into sugar by either dilute sulphuric acid or diastase. The
main difference between them consists in their habitudes with water and
iodine. The first forms with hot water a mucilaginous solution, which
constitutes, when cold, the paste of the laundress, and is tinged blue
by iodine; the second forms a granular precipitate, when its solution in
boiling-hot water is suffered to cool, which is tinged yellow by iodine;
the third affords, by cooling the concentrated solution, a gelatinous
mass, with a clear liquor floating over it, that contains little starch.
Its jelly becomes brown-gray with iodine.

1. _Ordinary starch._--This may be extracted from the following
grains:--wheat, rye, barley, oats, buckwheat, rice, maize, millet,
spelt; from the siliquose seeds, as peas, beans, lentiles, &c.; from
tuberous and tap roots, as those of the potato, the orchis, manioc;
arrowroot, batata, &c. Different kinds of corn yield very variable
quantities of starch. Wheat differs in this respect, according to the
varieties of the plant, as well as the soil, manure, season, and
climate. See BREAD.

Wheat partly damaged by long keeping in granaries, may be employed for
the manufacture of starch, as this constituent suffers less injury than
the gluten; and it may be used either in the ground or unground state.

1. _With unground wheat._--The wheat being sifted clean, is to be put
into cisterns, covered with soft water, and left to steep till it
becomes swollen and so soft as to be easily crushed between the fingers.
It is now to be taken out, and immersed in clear water of a temperature
equal to that of malting-barley, whence it is to be transferred into
bags, which are placed in a wooden chest containing some water, and
exposed to strong pressure. The water rendered milky by the starch being
drawn off by a tap, fresh water is poured in, and the pressure is
repeated. Instead of putting the swollen grain into bags, some prefer to
grind it under vertical edge-stones, or between a pair of horizontal
rollers, and then to lay it in a cistern, and separate the starchy
liquor by elutriation with successive quantities of water well stirred
up with it. The residuary matter in the sacks or cisterns contains much
vegetable albumen and gluten, along with the husks; when exposed to
fermentation, it affords a small quantity of starch of rather inferior
quality.

The above milky liquor, obtained by expression or elutriation, is run
into large cisterns, where it deposits its starch in layers successively
less and less dense; the uppermost containing a considerable proportion
of gluten. The supernatant liquor being drawn off, and fresh water
poured on it, the whole must be well stirred up, allowed again to
settle, and the surface-liquor again withdrawn. This washing should be
repeated as long as the water takes any perceptible colour. As the first
turbid liquor contains a mixture of gluten, sugar, gum, albumen, &c., it
ferments readily, and produces a certain portion of vinegar, which helps
to dissolve out the rest of the mingled gluten, and thus to bleach the
starch. It is, in fact, by the action of this fermented or soured water,
and repeated washing, that it is purified. After the last deposition and
decantation, there appears on the surface of the starch a thin layer of
a slimy mixture of gluten and albumen, which, being scraped off, serves
for feeding pigs or oxen; underneath will be found a starch of good
quality. The layers of different sorts are then taken up with a wooden
shovel, transferred into separate cisterns, where they are agitated with
water, and passed through fine sieves. After this pap is once more well
settled, the clear water is drawn off, the starchy mass is taken out,
and laid on linen cloths in wicker baskets, to drain and become
partially dry. When sufficiently firm, it is cut into pieces, which are
spread upon other cloths, and thoroughly desiccated in a proper
drying-room, which in winter is heated by stoves. The upper surface of
the starch is generally scraped, to remove any dusty matter, and the
resulting powder is sold in that state. Wheat yields, upon an average,
only from 35 to 40 per cent. of good starch. It should afford more by
skilful management.

2. In this country, wheat crushed between iron rollers is laid to steep
in as much water as will wet it thoroughly; in four or five days the
mixture ferments, soon afterwards settles, and is ready to be washed out
with a quantity of water into the proper fermenting vats. The common
time allowed for the steep, is from 14 to 20 days. The next process
consists in removing the stuff from the vats into a stout round basket
set across a back below a pump. One or two men keep going round the
basket, stirring up the stuff with strong wooden shovels, while another
keeps pumping water, till all the _farina_ is completely washed from the
bran. Whenever the subjacent back is filled, the liquor is taken out and
strained through hair sieves into square frames or cisterns, where it is
allowed to settle for 24 hours; after which the water is run off from
the deposited starch by plug taps at different levels in the side. The
thin stuff, called _slimes_, upon the surface of the starch, is removed
by a tray of a peculiar form. Fresh water is now introduced, and the
whole being well mixed by proper agitation, is then poured upon fine
silk sieves. What passes through is allowed to settle for 24 hours; the
liquor being withdrawn, and then the slimes, as before, more water is
again poured in, with agitation, when the mixture is again thrown upon
the silk sieve. The milky liquor is now suffered to rest for several
days, 4 or 5, till the starch becomes settled pretty firmly at the
bottom of the square cistern. If the starch is to have the blue tint,
called Poland, fine smalt must be mixed in the liquor of the last sieve,
in the proportion of 2 or 3 lbs. to the cwt. A considerable portion of
these slimes may, by good management, be worked up into starch by
elutriation and straining.

The starch is now fit for _boxing_, by shovelling the cleaned deposit
into wooden chests, about 4 feet long, 12 inches broad, and 6 inches
deep, perforated throughout, and lined with thin canvas. When it is
drained and dried into a compact mass, it is turned out by inverting the
chests upon a clean table, where it is broken into pieces 4 or 5 inches
square, by laying a ruler underneath the cake, and giving its surface a
cut with a knife, after which the slightest pressure with the hand will
make the fracture. These pieces are set upon half-burned bricks, which
by their porous capillarity imbibe the moisture of the starch, so that
its under surface may not become hard and horny. When sufficiently dried
upon the bricks, it is put into a stove (which resembles that of a sugar
refinery), and left there till tolerably dry. It is now removed to a
table, when all the sides are carefully scraped with a knife; it is next
packed up in the papers in which it is sold; these packages are returned
into the stove, and subjected to a gentle heat during some days; a point
which requires to be skilfully regulated.

Mr. Samuel Hall obtained a patent for bleaching starch by chloride of
lime in 1821. Chlorine water would probably be preferable, and might
prove useful in operating upon damaged wheat.

The sour water of the starch manufacture contains, according to
Vauquelin, acetic acid, acetate of ammonia, alcohol, phosphate of lime,
and gluten.

During the drying, starch splits into small prismatic columns, of
considerable regularity. When kept dry, it remains unaltered for a very
long period. When it is heated to a certain degree in water, the
envelopes of its spheroidal particles burst, and the _farina_ forms a
mucilaginous emulsion, magma, or paste. When this apparent solution is
evaporated to dryness, a brittle horny-looking substance is obtained,
quite different in aspect from starch, but similar in chemical
habitudes. When the moist paste is exposed for 2 or 3 months to the air
in summer, the starch is converted into sugar to the amount of one-third
or one-half of its weight, into gum, and gelatinous starch called
_amidine_ by De Saussure, with occasionally a resinous matter. This
curious change goes on even in close vessels.

_Starch from potatos._--From the following table of analyses, it appears
that potatos contain from 24 to 30 per cent. of dry substance:--

  +-------------------+-------+-----------+--------+-----------+------+
  |                   |       |  Fibrous  |  Veg.  |Gum, Sugar,|      |
  |                   |Starch.|parenchyma.|Albumen.|and Salts. |Water.|
  +-------------------+-------+-----------+--------+-----------+------+
  |Red potato         | 15·0  |    7·0    |   1·4  |    9·2    | 75·0 |
  |Germinating potatos| 15·2  |    6·8    |   1·3  |    3·7    | 73·0 |
  |Kidney potatos     |  9·1  |    8·8    |   0·8  |    ---    | 81·3 |
  |Large red potatos  | 12·9  |    6·0    |   0·7  |    ---    | 78·0 |
  |Sweet potatos      | 15·1  |    8·2    |   0·8  |    ---    | 74·3 |
  |Peruvian potatos   | 15·0  |    5·2    |   1·9  |    1·9    | 76·0 |
  |English potatos    | 12·9  |    6·8    |   1·1  |    1·7    | 77·5 |
  |Parisian potatos   | 13·3  |    6·8    |   0·9  |    4·8    | 73·1 |
  +-------------------+-------+-----------+--------+-----------+------+

[Illustration: 1047 1048]

_Manufacture of potato starch._--The potatos are first washed in a
cylindrical cage formed of wooden spars, made to revolve upon a
horizontal axis, in a trough filled with water to the level of the axis.
They are then reduced to a pulp by a rasping machine, similar to that
represented in _figs._ 1047, 1048., where _a_ is a wooden drum covered
with sheet-iron, roughened outside with numerous prominences, made by
punching out holes from the opposite side. It is turned by a winch fixed
upon each end of the shaft. The drum is enclosed in a square wooden box,
to prevent the potato-mash from being scattered about. The hopper _b_ is
attached to the upper frame, has its bottom concentric with the
rasp-drum, and nearly in contact with it. The pulp chest _c_ is made to
slide out, so as when full to be readily replaced by another. The two
slanting boards _d_, _d_, conduct the pulp into it. A moderate stream of
water should be made to play into the hopper upon the potatos, to
prevent the surface of the rasp from getting foul with fibrous matter.
Two men, with one for a relay, will rasp, with such a machine, from
2-1/2 to 3 tons of potatos in 12 hours.

The potato pulp must be now elutriated upon a fine wire or hair sieve,
which is set upon a frame in the mouth of a large vat, while water is
made to flow upon it from a spout with many jets. The pulp meanwhile
must be stirred and kneaded by the hand, or by a mechanical
brush-agitator, till almost nothing but fibrous particles are left upon
the sieve. These, however, generally retain about 5 per cent. of starch,
which cannot be separated in this way. This parenchyma should therefore
be subjected to a separate rasping upon another cylinder. The water
turbid with starch is allowed to settle for some time in a back; the
supernatant liquor is then run by a cock into a second back, and after
some time into a third, whereby the whole starch will be precipitated.
The finest powder collects in the last vessel. The starch thus obtained,
containing 33 per cent. of water, may be used either in the moist state,
under the name of _green fecula_, for various purposes, as for the
preparation of dextrine, and starch syrup; or it may be preserved under
a thin layer of water, which must be renewed from time to time, to
prevent fermentation; or lastly, it may be taken out and dried.

In trials made with St. Etienne’s rasp and starch machinery, in Paris,
which was driven by two horses, nearly 18 cwt. of potatos were put
through all the requisite operations in one hour, including the pumping
of the water. The product in starch amounted to from 17 to 18 per cent.
of the potatos. The quicker the process of potato-starch making, the
better is its quality.

_Starch from certain foreign plants._--1. From the pith of the _sago
palm_. See SAGO.

2. From the roots of the _Maranta arundinacea_, of Jamaica, the Bahamas,
and other West India islands, the powder called arrow-root is obtained,
by a process analogous to that for making potato starch.

3. From the root of the _Manioc_, which also grows in the West Indies,
as well as in Africa, the _cassava_ is procured, by a similar process.
The juice of this plant is poisonous, from which the wholesome starch is
deposited. When dried with stirring upon hot iron plates, it
agglomerates into small lumps, called _tapioca_; being a gummy fecula.

The characters of the different varieties of starch can be learnt only
from microscopic observation; by which means also their sophistication
or admixture may be readily ascertained.

Starch, from whatever source obtained, is a white soft powder, which
feels crispy, like flowers of sulphur, when pressed between the fingers;
it is destitute of taste and smell, unchangeable in the atmosphere, and
has a specific gravity of 1·53. I have already described the particles
as spheroids enclosed in a membrane. The potato contains some of the
largest, and the millet the smallest. Potato starch consists of
truncated ovoids, varying in size from 1/300 to 1/3000 of an inch;
arrow-root, of ovoids varying in size from 1/800 to 1/2000 of an inch;
flower starch, of insulated globules about 1/1000 of an inch; cassava,
of similar globules assembled in groups. These measurements I have made
with a good achromatic microscope, and a divided glass-slip micrometer
of Tully.

For the saccharine changes which starch undergoes by the action of
_diastase_, see FERMENTATION.

_Lichenine_, a species of starch obtained from Iceland moss (_Cetraria
islandica_), as well as _inuline_, from elecampane (_Inula Helenium_),
are rather objects of chemical curiosity, than of manufactures.

There is a kind of starch made in order to be converted into gum for the
calico-printer. This conversion having been first made upon the great
scale in this country, has occasioned the product to be called British
gum. The following is the process pursued in a large and well conducted
establishment near Manchester. A range of four wooden cisterns, each
about 7 or 8 feet square, and 4 feet deep, is provided. Into each of
them 2000 gallons of water being introduced, 12-1/2 loads of flour are
stirred in. This mixture is set to ferment upon old leaven left at the
bottom of the backs, during 2 or 3 days. The contents are then stirred
up, and pumped off into 3 stone cisterns, 7 feet square and 4 feet deep;
as much water being added, with agitation, as will fill the cisterns to
the brim. In the course of 24 hours the starch forms a firm deposit at
the bottom; and the water is then syphoned off. The gluten is next
scraped from the surface, and the starch is transferred into wooden
boxes pierced with holes, which may be lined with coarse cloth, or not,
at the pleasure of the operator.

The starch, cut into cubical masses, is put into iron trays, and set to
dry in a large apartment, two stories high, heated by a horizontal
cylinder of cast-iron traversed by the flame of a furnace. The drying
occupies two days. It is now ready for conversion into gum, for which
purpose it is put into oblong trays of sheet iron, and heated to the
temperature of 300° F. in a cast-iron oven, which holds four of these
trays. Here it concretes into irregular semi-transparent yellow-brown
lumps, which are ground into fine flour between mill-stones, and in
this state brought to the market. In this roasted starch, the vesicles
being burst, their contents become soluble in cold water. British gum is
not convertible into sugar, as starch is, by the action of dilute
sulphuric acid; nor into mucic acid, by nitric acid; but into the
oxalic; and it is tinged purple-red by iodine. It is composed, in 100
parts, of 35·7 carbon, 6·2 hydrogen, and 58·1 oxygen; while starch is
composed of, 43·5 carbon, 6·8 hydrogen, and 49·7 oxygen.

To prove whether starch be quite free from gluten, or whether it be
mixed with any wheat flour, diffuse 12 grains of it through six ounces
of water, heat the mixture to boiling, stirring it meanwhile with a
glass slip. If the starch be pure, no froth will be seen upon the
surface of the pasty fluid; or if any be produced during the stirring,
it will immediately subside after it; but if the smallest portion of
gluten be present, much froth will be permanently formed, which may be
raised by stirring into the appearance of soap-suds.

[Illustration: 1049 1050]


STARCHING AND STEAM-DRYING APPARATUS. The system of hollow cylinders,
for drying goods in the processes of bleaching or calico-printing, is
represented in _fig._ 1049. in a longitudinal section, and in _fig._
1050. in a top view; but the cylinders are supposed to be broken off in
the middle, as it was needless to repeat the parts at the other end,
which are sufficiently shown in the section.

A is the box containing the paste, when the goods are to be starched or
stiffened: _a_, a winch, when it is desired to turn the machine by
hand, though it is always moved by power in considerable factories; _b_,
is the driving pinion; _d_, _d´_, two brass rollers with iron shafts,
the undermost of which is moved by the wheel _c_, in geer with the
pinion _b_. The uppermost roller _d´_, is turned by the friction with
the former, _d_, being pressed upon it by the weighted lever _h_; _e_ is
the trough filled with the paste, which rests upon the bars _f_, and may
be placed higher or lower by means of the adjusting screws _g_,
according as the roller _d_ is to be plunged more or less deeply. A
brass roller _i_ serves to force down the cloth into the paste.

B, is the drying part of the machine: _k_, _k_, its iron framing; _l_,
_l_, &c., five drums, or hollow copper cylinders, heated with steam:
_m_, _m_, _m_, &c., small copper drums, in pairs, turning freely on
shafts under the former, for stretching the goods, and airing them,
during their passage through the machine: _n_, _n_, is the main
steam-pipe, from which branch off small copper tubes, _o_, _o_, &c.,
which conduct the steam through stuffing-boxes into the cavity of the
drying-drums. There are similar tubes upon the other ends of the drums,
for discharging the condensed water through similar stuffing-boxes: _q_,
_q_, are valves, opening internally, for admitting the air whenever the
steam is taken _off_, or becomes feeble, to prevent the drums from being
crushed by the unbalanced pressure of the atmosphere upon their external
surfaces.

C, is the cloth-beam, from which the starching roller draws forward the
goods; _d_, _d_, are two rollers, of which the lower is provided with a
band-pulley or rigger, driven by a similar pulley fixed upon the shaft
of the starching roller _d_. These two rollers pull the goods through
the drying machine, and then let them fall either upon a table or the
floor.


STEAM, is the vapour of hot water; the discussion of which belongs to
chemistry, physics, and engineering. Certain practical applications of
the subject will be found in the article EVAPORATION.


STEARIC ACID, improperly called STEARINE (_Talgsaüre_, Germ.), is the
solid constituent of fatty substances, as of tallow and olive oil,
converted into a crystalline mass by saponification with alkaline
matter, and abstraction of the alkali by an acid. By this process, fats
are convertible into three acids, called Stearic, Margaric, and Oleic;
the first two being solid, and the last liquid. The stearine, of which
_factitious wax_ candles are made, consists of the stearic and margaric
acids combined. These can be separated from each other only by the
agency of alcohol, which holds the margaric acid in solution after it
has deposited the stearic in crystals. Pure stearic acid is prepared,
according to its discoverer, Chevreul, in the following way:--Make a
soap, by boiling a solution of potash and mutton-suet in the proper
equivalent proportions (see SOAP); dissolve one part of that soap in 6
parts of hot water, then add to the solution 40 or 50 parts of cold
water, and set the whole into a place whose temperature is about 52°
Fahrenheit. A substance falls to the bottom, possessed of pearly lustre,
consisting of the bi-stearate and bi-margarate of potash; which is to be
drained and washed upon a filter. The filtered liquor is to be
evaporated, and mixed with the small quantity of acid necessary to
saturate the alkali left free by the precipitation of the above
bi-salts. On adding water to it afterwards, the liquor affords a fresh
quantity of bi-stearate and bi-margarate. By repeating this operation
with precaution, we finally arrive at a point when the solution contains
no more of these solid acids, but only the oleic. The precipitated
bi-salts are to be washed and dissolved in hot alcohol, of specific
gravity 0·820, of which they require about 24 times their weight. During
the cooling of the solution, the bi-stearate falls down, while the
greater part of the bi-margarate, and the remainder of the oleate,
remain dissolved. By once more dissolving in alcohol, and crystallizing,
the bi-stearate will be obtained alone; as may be proved by decomposing
a little of it in water at a boiling heat, with muriatic acid, letting
it cool, washing the stearic acid obtained, and exposing it to heat,
when, if pure, it will not fuse in water under the 158th degree of
Fahrenheit’s scale. If it melts at a lower heat, it contains more or
less margaric acid. The purified bi-stearate being decomposed by boiling
in water along with any acid, as the muriatic, the disengaged stearic
acid is to be washed by melting in water, then cooled and dried.

Stearic acid, prepared by the above process, contains combined water,
from which it cannot be freed. It is insipid and inodorous. After being
melted by heat, it solidifies at the temperature of 158° Fahrenheit, and
affects the form of white brilliant needles grouped together. It is
insoluble in water, but dissolves in all proportions in boiling
anhydrous alcohol, and on cooling to 122°, crystallizes therefrom, in
pearly plates; but if the concentrated solution be quickly cooled to
112°, it forms a crystalline mass. A dilute solution affords the acid
crystallized in large white brilliant scales. It dissolves in its own
weight of boiling ether of 0·727, and crystallizes on cooling in
beautiful scales, of changing colours. It distils over _in vacuo_
without alteration; but if the retort contains a little atmospheric air,
a small portion of the acid is decomposed during the distillation; while
the greater part passes over unchanged, but slightly tinged brown, and
mixed with traces of empyreumatic oil. When heated in the open air, and
kindled, stearic acid burns like wax. It contains 3·4 per cent. of
water, from which it may be freed by combining it with oxide of lead.
When this anhydrous acid is subjected to ultimate analysis, it is found
to consist of--80 of carbon, 12·5 hydrogen, and 7·5 oxygen, in 100
parts. Stearic acid displaces, at a boiling heat in water, carbonic acid
from its combinations with the bases; but in operating upon an alkaline
carbonate, a portion of the stearic acid is dissolved in the liquor
before the carbonic acid is expelled. This decomposition is founded upon
the principle, that the stearic acid transforms the salt into a
bicarbonate, which is decomposed by the ebullition.

Stearic acid put into a strong watery infusion of litmus, has no action
upon it in the cold; but when hot, the acid combines with the alkali of
the litmus, and changes its blue colour to red; so that it has
sufficient energy to abstract from the concentrated tincture all the
alkali required for its neutralization. If we dissolve bi-stearate of
potash in weak alcohol, and pour litmus water, drop by drop, into the
solution, this will become red, because the litmus will give up its
alkali to a portion of the bi-stearate, and will convert it into neutral
stearate. If we now add cold water, the reddened mixture will resume its
blue tint, and will deposit bi-stearate of potash in small spangles. In
order that the alcoholic solution of the bi-stearate may redden the
litmus, the alcohol should not be very strong.

From the composition of stearate of potash, the atomic weight of the
acid appears to be 106·6; hydrogen being 1; for 18 : 48 × 2 ∷ 100 :
533·3 = 5 atoms of acid.

From the stearate of soda, it appears to be 104; and from that of lime,
102. The stearate of lead, by Chevreul, gives 109 for the atomic weight
of the acid.

The margaric and oleic acids seem to have the same neutralizing power,
and the same atomic weight.

The preceding numbers will serve to regulate the manufacture of stearic
acid for the purpose of making candles. Potash and soda were first
prescribed for saponifying fat, as may be seen in M. Gay Lussac’s
patent, under the article CANDLE; and were it not for the cost of these
articles, they are undoubtedly preferable to all others in a chemical
point of view. Of late years lime has been had recourse to, with perfect
success, and has become subservient to a great improvement in
candle-making. The stearine block now made by many London houses, though
containing not more than 2 or 3 per cent. of wax, is hardly to be
distinguished from the purified produce of the bee. The first process is
to boil the fat with quicklime and water in a large tub, by means of
perforated steam pipes distributed over its bottom. From the above
statements we see that about 11 parts of dry lime are fully equivalent
to 100 of stearine and oleine mixed: but as the lime is in the state of
hydrate, 14 parts of it will be required when it is perfectly pure; in
the ordinary state, however, as made from average good limestone, 16
parts may be allowed. After a vigorous ebullition of 3 or 4 hours, the
combination is pretty complete. The stearate being allowed to cool to
such a degree as to allow of its being handled, becomes a concrete mass,
which must be dug out with a spade, and transferred into a contiguous
tub, in order to be decomposed with the equivalent quantity of sulphuric
acid diluted with water, and also heated with steam. Four parts of
concentrated acid will be sufficient to neutralize three parts of slaked
lime. The saponified fat now liberated from the lime, which is thrown
down to the bottom of the tub in the state of sulphate, is skimmed off
the surface of the watery menstruum into a third contiguous tub, where
it is washed with water and steam.

The washed mixture of stearic, margaric, and oleic acids, is next cooled
in tin pans; then shaved by large knives, fixed on the face of a
fly-wheel, called a tallow cutter, preparatory to its being subjected in
canvas or caya bags to the action of a powerful hydraulic press. Here a
large portion of the oleic acid is expelled, carrying with it a little
of the margaric. The pressed cakes are now subjected to the action of
water and steam once more, after which the supernatant stearic acid is
run off, and cooled in moulds. The cakes are then ground by a rotatory
rasping-machine to a sort of mealy powder, which is put into canvas
bags, and subjected to the joint action of steam and pressure in a
horizontal hydraulic press of a peculiar construction, somewhat similar
to that which has been long used in London for pressing spermaceti. The
cakes of stearic acid thus freed completely from the margaric and oleic
acids, are subjected to a final cleansing in a tub with steam, and then
melted into hemispherical masses called blocks. When these blocks are
broken, they display a highly crystalline texture, which would render
them unfit for making candles. This texture is therefore broken down or
comminuted by fusing the stearine in a plated copper pan, along with one
thousandth part of pulverized arsenious acid, after which it is ready to
be cast into candles in appropriate moulds. See CANDLE.

[Illustration: 1051 _Scale 3-20ths of an inch to the foot._]

[Illustration: 1052 1053]


STEARINE COLD PRESS. The cold hydraulic press, as mounted by Messrs.
Maudslay and Field, for squeezing out the oleic acid from saponified
fat, or the oleine from coco-nut lard, is represented in plan in _fig._
1051.; in side view of pump in _fig._ 1052.; and in elevation, _fig._
1053.; where the same letters refer to like objects.

A, A, are two hydraulic presses; B the frame; C, the cylinder; D, the
piston or ram; E, the follower; F, the recess in the bottom to receive
the oil; G, twilled woollen bags with the material to be pressed, having
a thin plate of wrought iron between each; H, apertures for the
discharge of the oil; I, cistern in which the pumps are fixed; K,
framing for machinery to work in; L, two pumps, large and small, to
inject the water into the cylinders; M, a frame containing three double
branches; N, three branches, each having two stops or plugs, by which
the action of one of the pumps may be intercepted from, or communicated
to, one or both of the presses; the large pump is worked at the
beginning of the operation, and the small one towards the end; by these
branches, one or both presses may be discharged when the operation is
finished; O, two pipes from the pumps to the branches; P, pipe to return
the water from the cylinders to the cisterns; Q, pipes leading from the
pumps through the branches to the cylinders; R, conical drum, fixed upon
the main shaft Y, driven by the steam-engine of the factory; S, a like
conical drum to work the pumps; T, a narrow leather strap to communicate
the motion from R to S; U, a long screw bearing a nut, which works along
the whole length of the drum; V, the fork or guide for moving the strap
T; W, W, two hanging bearings to carry the drum S; X, a pulley on the
spindle of the drum S; Y, the main shaft; Z, fly-wheel with groove on
the edge, driven by the pulley X; on the axis of S, is a double crank,
which works the two pumps L. _a_, is a pulley on the end of the long
screw U; an endless cord passes twice round this pulley, and under a
pulley fixed in the weight _b_; by laying hold of both sides of his
cord, and raising or lowering it, the forked guide V, and the leather
strap T, are moved backwards or forwards, by means of the nut fixed in
the guide, so as to accelerate or retard at pleasure the speed of the
working of the pumps; _c_, is a piece of iron, with a long slit, in
which a pin, attached to the fork V, travels, to keep it in the vertical
position.


STEATITE (_Soapstone_; _Craie de Briançon_, Fr.; _Speckstein_, Germ.);
is a mineral of the magnesian family. It has a grayish-white or
greenish-white colour, often marked with dendritic delineations, and
occurs massive, as also in various supposititious crystalline forms; it
has a dull or fatty lustre; a coarse splintery fracture, with
translucent edges; a shining streak; it writes feebly; is soft, and
easily cut with a knife; but somewhat tough; does not adhere to the
tongue; feels very greasy; infusible before the blowpipe; specific
gravity from 2·6 to 2·8. It consists of--silica, 44; magnesia, 44;
alumina, 2; iron, 7·3; manganese, 1·5; chrome, 2; with a trace of lime.
It is found frequently in small contemporaneous veins that traverse
serpentine in all directions, as at Portsoy, in Shetland, in the
limestone of Icolmkiln, in the serpentine of Cornwall, in Anglesey, in
Saxony, Bavaria (at Bayruth), Hungary, &c. It is used in the manufacture
of porcelain. It makes the biscuit semi-transparent, but rather brittle,
and apt to crack with slight changes of heat. It is employed for
polishing serpentine, marble, gypseous alabaster, and mirror glass; as
the basis of cosmetic powders; as an ingredient in anti-attrition
pastes; it is dusted in powder upon the inside of boots, to make the
feet glide easily into them; when rubbed upon grease-spots in silk and
woollen clothes, it removes the stains by absorption; it enters into the
composition of certain crayons, and is used itself for making traces
upon glass, silk, &c. The spotted steatite, cut into cameos and
calcined, assumes an onyx aspect. Soft steatite forms excellent stoppers
for the chemical apparatus used in distilling or subliming corrosive
vapours. Lamellar steatite is TALC.


STEEL (_Acier_, Fr.; _Stahl_, Germ.); as a carburet of iron, has already
been considered under that metal. I shall treat in this article more
particularly of its manufacture and technical relations.

1. _Steel of cementation, bar or blistered steel._--With the exception
of the Ulverstone charcoal iron, no bars are manufactured in Great
Britain capable of conversion into steel at all approaching in quality
to that made from the Madras, Swedish, and Russian irons, so largely
imported for that purpose. The first rank is assigned to the Swedish
iron stamped with a circle enclosing the letter L (hence called hoop L);
which fetches the high price of 36_l._ 10_s._ per ton, while excellent
English coke-iron may be had for one-fifth of the price. The other
Swedish irons are sold at a much lower rate, though said to be
manufactured in the same way; and therefore the superiority of the
Dannemora iron must be owing to some peculiarity in the ore from which
it is smelted. The steel recently made in the Indian steel-works at
Chelsea, from Mr. Heath’s Madras iron, rivals that from the hoop L.

[Illustration: 1054 1055]

The Sheffield furnace for making bar or blistered steel, called the
furnace of cementation, is represented in _fig._ 1054. in a cross
section, and in _fig._ 1055. in a ground plan. The hearth of this oblong
quadrangular furnace, is divided by a grate into two parts, upon each
side of which there is a chest _a_, called a _trough_, made of
fire-clay, or fire-tiles. The breadth of the grate varies according to
the quality of the fuel. _b_, _b_, are air-holes; _c_, _c_, flues
leading to the chimney _d_, _d_. To aid the draught of the smoke and the
flame, an opening _e_, is made in the middle of the flat arch of the
furnace. In one of its shorter sides (ends), there are orifices _f_,
_f_, through which the long bars of iron may be put in and taken out;
_g_, is the door by which the steel-maker enters, in filling or emptying
the trough; _h_, is a proof hole, at which small samples of the steel,
in the act of its conversion, may be drawn out. The furnace is built
under a conical hood or chimney, from 30 to 50 feet high, for aiding the
draught, and carrying off the smoke.

The two chests are built of fire-stone grit. They are 8, 10, or even 15
feet long, and from 26 to 36 inches in width and depth; the lower and
smaller they are, the more uniform will the quality of the steel be. A
great breadth and height of trough are incompatible with equability of
the cementing temperature. The sides are a few inches thick. The space
between them is at least a foot wide. They should never rest directly
upon the sole of the furnace, but must have their bottom freely played
upon by the flame, as well as the sides and top. The degree of heat is
regulated by openings in the arch, or upon the long sides of the
furnace, which lead to the chimney; as also by the greater or less
quantity of air admitted below the grate, as in glass-house furnaces.

The _cement_ consists of ground charcoal (sometimes of soot), mixed with
one-tenth of ashes, and some common salt; the charcoal of hard wood
being preferred. Ground coke is inadmissible, on account of the sulphur,
silica, and clay which it generally contains. Possibly the salt serves
to vitrify the particles of silica in the charcoal, and thus to prevent
their entering into combination with the steel. As for the ashes, it is
difficult to discover their use. The best steel may be made without
their presence. The bottom of the trough being covered with two inches
of the powder of cementation, the bars are laid along in it, upon their
narrow edge, the side bar being one inch from the trough, and the rest
being from 1/2 to 3/4 of an inch apart. Above this first layer of iron
bars, fully half an inch depth of the powder is spread, then a new
series of bars is stratified, and so on till the trough is filled within
six inches of the top. This space is partially filled with old cement
powder, and is covered with refractory damp sand. Sometimes the trough
is filled to the surface with the old cement, and then closely covered
with fire-tiles. The bars should never be allowed to touch each other,
or the trough. The fire must be carefully urged from 2 to 4 days, till
it acquires the temperature of 100° Wedgewood; which must be steadily
maintained during the 4, 6, 8, or 10 days requisite for the cementation;
a period dependent on the size of the furnace, and which is determined
by the examination of the proof pieces, taken out from time to time.

In the front or remote end of the furnace, _fig._ 1054., a door is left
in the outer building, corresponding to a similar one in the end of the
interior vault, through which the workman enters for charging the
furnace with charcoal and iron bars, as also for taking out the steel
after the conversion. Small openings are likewise made in the ends of
the chests, through which the extremities of a few bars are left
projecting, so that they may be pulled out and examined, through small
doors opposite to them in the exterior walls. These _tap_ holes, as they
are called, should be placed near the centre of the end stones of the
chests, that the bars may indicate the average state of the process. The
joinings of the fire-stones are secured with a finely ground Stourbridge
clay.

The interval between the two chests (in furnaces containing two, for
many have only one,) being covered with an iron platform, the workman
stands on it, and sifts a layer of charcoal on the bottom of the chests
evenly, about half an inch thick; he then lays a row of bars, cut to the
proper length, over the charcoal, about an inch from each other; he next
sifts on a second stratum of charcoal-dust, which, as it must serve for
the bars above, as well as below, is made an inch thick; thus, he
continues to stratify, till the chest be filled within two inches of the
top; and he covers the whole with the earthy detritus found at the
bottom of grindstone troughs, or any convenient fire-loam. It is obvious
that the second series of bars should correspond vertically with the
interstices between the first series, and so in succession. The
trial-rods are left longer than the others, and their projecting ends
are encrusted with fire-clay, or imbedded in sand. The iron platform
being removed, and all the openings into the vault closed, the fire is
lighted, and very gradually increased, to avoid every risk of cracking
the gritstone by too sudden a change of temperature; and the ignition
being finally raised to about 100° Wedgewood, but not higher, for fear
of melting the metal, must be maintained at a uniform pitch, till the
iron have absorbed the desired quantity of carbon, and have been
converted as highly as the manufacturer intends for his peculiar object.
From six to eight days may be reckoned a sufficient period for the
production of steel of moderate hardness, and fit for tilting into shear
steel. A softer steel, for saws and springs, takes a shorter period; and
a harder steel, for fabricating chisels used in cutting iron, will need
longer exposure to the ignited charcoal. But, for a few purposes, such
as the bits for boring cast iron, the bars are exposed to two or three
successive processes of cementation, and are hence said to be twice or
thrice converted into steels. The higher the heat of the furnace, the
quicker is the process of conversion.

The furnace being suffered to cool, the workman enters it again, and
hands out the steel bars, which being covered with blisters, from the
formation and bursting of vesicles on the surface filled with gaseous
carbon, is called _blistered steel_. This steel is very irregular in its
interior texture, has a white colour, like frosted silver, and displays
crystalline angles and facettes, which are larger the further the
cementation has been urged, or the greater the dose of carbon. The
central particles are always smaller than those near the surface of the
bar.

In such a furnace as the above, twelve tons of bar iron may be converted
at a charge. But other furnaces are constructed with one chest, which
receives six or eight tons at a time; the small furnaces, however,
consume more fuel in proportion than the larger.

The absorption and action of the carbonaceous matter, to the amount of
about a half per cent., occasions fissures and cavities in the substance
of the blistered bars, which render the steel unfit for any useful
purpose in tool-making, till it be condensed and rendered uniform by the
operation of _tilting_, under a powerful hammer driven by machinery. See
IRON.[59]

  [59] For minute details of the parts, see the excellent article
  TILTING-HAMMER, in _Rees’s Cyclopædia_.

The heads of the tilt-hammers for steel weigh from one and a half to two
hundred pounds. Those in the neighbourhood of Sheffield are much simpler
than the one referred to in the note. They are worked by a small
water-wheel, on whose axis is another wheel, bearing a great number of
cams or wipers on its circumference, which strike the tail of the hammer
in rapid succession, raise its head, and then let it fall smartly on the
hot metal rod, dexterously presented on its several parts to the anvil
beneath it, by the workman. The machinery is adapted to produce from 300
to 400 blows per minute; which on this plan requires an undue and
wasteful velocity of the float-boards. Were an intermediate toothed
wheel substituted between the water-wheel and the wiper-wheel, so that
while the former made one turn, the latter might make three, a much
smaller force of water would do the work. The anvils of the tilt-hammer
are placed nearly on a level with the floor of the mill-house; and the
workman sits in a fosse, dug on purpose, in a direction perpendicular to
the line of the helve, on a board suspended from the roof of the
building by a couple of iron rods. On this swinging seat, he can advance
or retire with the least impulse of his feet, pushing forward the steel
bar, or drawing it back with equal rapidity and convenience.

At a small distance from each tilt, stands the forge-hearth, for heating
the steel. The bellows for blowing the fire are placed above-head, and
are worked by a small crank fixed on the end of the axis of the wheel,
the air being conveyed by a copper pipe down to the nozzle. Each workman
at the tilt has two boys in attendance, to serve him with hot rods, and
to take them away after they are hammered. In small rods, the bright
ignition originally given at the forge soon declines to darkness; but
the rapid impulsions of the tilt revive the redness again in all the
points near the hammer; so that the rod, skilfully handled by the
workman, progressively ignites where it advances to the strokes.
Personal inspection alone can communicate an adequate idea of the
precision and celerity with which a rude steel rod is stretched and
fashioned into an even, smooth, and sharp-edged prism, under the
operation of the tilt-hammer. The heat may be clearly referred to the
prodigious friction among the particles of so cohesive a metal, when
they are made to slide so rapidly over each other in every direction
during the elongation and squaring of the rod.

2. _Shear steel_ derives its name from the accidental circumstance of
the shears for dressing woollen cloth being usually forged from it. It
is made by binding into a bundle, with a slender steel rod, four
parallel bars of blistered steel, previously broken into lengths of
about 18 inches, including a fifth of double length, whose projecting
end may serve as a handle. This faggot, as it is called, is then heated
in the forge-hearth to a good welding heat, being sprinkled over with
sand to form a protecting film of iron slag, carried forthwith to the
tilt, and notched down on both sides to unite all the bars together, and
close up every internal flaw or fissure. The mass being again heated,
and the binding rings knocked off, is drawn out into a uniform rod of
the size required. Manufacturers of cutlery are in the habit of
purchasing the blistered bars at the conversion furnaces, and sending
them to tilt-mills to have them drawn out to the proper size, which is
done at regular prices to the trade; from 5 to 8 per cent. discount
being allowed on the rude bars for waste in the tilting. The metal is
rendered so compact by the welding and hammering, as to become
susceptible of a much finer polish than blistered steel can take; while
the uniformity of its body, tenacity, and malleability are at the same
time much increased; by which properties it becomes well adapted for
making table knives and powerful springs, such as those of gun-locks.
The steel is also softened down by this process, probably from the
expulsion of a portion of its carbon during the welding and subsequent
heats; and if these be frequently or awkwardly applied, it may pass back
into common iron.

3. _Cast steel_ is made by melting, in the best fire-clay crucibles,
blistered steel, broken down into small pieces of convenient size for
packing; and as some carbon is always dissipated in the fusion, a
somewhat highly converted steel is used for this purpose. The furnace is
a square prismatic cavity, lined with fire-bricks, 12 inches in each
side, and 24 deep, with a flue immediately under the cover, 3-1/2 inches
by 6, for conducting the smoke into an adjoining chimney of considerable
height. In some establishments a dozen such furnaces are constructed in
one or two ranges, their tops being on a level with the floor of the
laboratory, as in brass-foundries, for enabling the workmen more
conveniently to inspect, and lift out, the crucibles with tongs. The
ash-pits terminate in a subterraneous passage, which supplies the grate
with a current of cool air, and serves for emptying out the ashes. The
crucible, stands of course, on a sole-piece of baked fire-clay; and its
mouth is closed with a well-fitted lid. Sometimes a little bottle-glass,
or blast-furnace slag, is put into the crucible, above the steel pieces,
to form a vitreous coating, that may thoroughly exclude the air from
oxidizing the metal. The fuel employed in the cast-steel furnace is a
dense coke, brilliant and sonorous, broken into pieces about the size of
an egg, one good charge of which is sufficient. The tongs are furnished
at the fire end with a pair of concave jaws, for embracing the curvature
of the crucible, and lifting it out whenever the fusion is complete. The
lid is then removed, the slag or scoriæ cleared away, and the liquid
metal poured into cast-iron octagonal or rectangular moulds, during
which it throws out brilliant scintillations.

Cast-steel works much harder under the hammer than shear steel and will
not, in its usual state, bear much more than a cherry-red heat without
becoming brittle; nor can it bear the fatigue incident to the welding
operation. It may, however, be firmly welded to iron, through the
intervention of a thin film of vitreous boracic acid, at a moderate
degree of ignition. Cast steel, indeed, made from a less carburetted bar
steel, would be susceptible of welding and hammering at a higher
temperature; but it would require a very high heat for its preparation
in the crucible.

Iron may be very elegantly plated with cast steel, by pouring the liquid
metal from the crucible into a mould containing a bar of iron polished
on one face. In this circumstance the adhesion is so perfect as to admit
of the two metals being rolled out together; and in this way the chisels
of planes and other tools may be made, at a moderate rate and of
excellent quality, the cutting-edge being formed in the steel side. Such
instruments combine the toughness of iron with the hardness of steel.

For correcting the too high carbonization of steel, or equalizing the
too highly converted exterior of a bar with the softer steel of the
interior, the metal requires merely to be imbedded, at a cementing heat,
in oxide of iron or manganese; the oxygen of which soon abstracts the
injurious excess of carbon, so that the outer layers may be even
converted into soft iron, while the axis continues steely; because the
decarbonizing advances far more rapidly than the carbonizing.

[Illustration: 1056]

_Fig._ 1056. represents the mould for making crucibles for the
cast-steel works. M, M, is a solid block of wood, to support the
two-handled outside mould N, N. This being rammed full of the proper
clay dough or compost (see CRUCIBLE), the inner mould is to be then
pressed vertically into it, till it reaches the bottom P, being directed
and facilitated in its descent by the point _K_. A cord passes through
O, by which the inner mould is suspended over a pulley, and guided in
its motions.

When a plate of polished steel is exposed to a progressive heat, it
takes the following colours in succession: 1. a faint yellow; 2. a pale
straw-colour; 3. a full yellow; 4. a brown yellow; 5. a brown with
purple spots; 6. a purple; 7. a bright blue; 8. a full blue; 9. a dark
blue, verging on black; after which the approach to ignition supersedes
all these colours. If the steel plate has been previously hardened by
being dipped in cold water or mercury when red-hot, then those
successive shades indicate or correspond to successive degrees of
softening or tempering. Thus, No. 1. suits the hard temper of a lancet,
which requires the finest edge, but little strength of metal; No. 2. a
little softer, for razors and surgeons’ amputating instruments; No. 3.
somewhat more toughness, for penknives; No. 4. for cold chisels and
shears for cutting iron; No. 5. for axes and plane-irons; No. 6. for
table knives and cloth shears; No. 7. for swords and watch springs; No.
8. for small fine saws and daggers; No. 9. for large saws, whose teeth
need to be set with pliers, and sharpened with a file. After ignition,
if the steel be very slowly cooled, it becomes exceedingly soft, and fit
for the engraver’s purposes. Hardened steel may be tempered to the
desired pitch, by plunging it in metallic baths heated to the proper
thermometric degree, as follows: for No. 1. 430° Fahr.; No. 2. 450°; No.
3. 470°; No. 4. 490°; No. 5. 510°; No. 6. 530°; No. 7. 550°; No. 8.
560°; No. 9. 600°.

Small steel tools are most frequently tempered, after hardening, by
covering their surface with a thin coat of tallow, and heating them in
the flame of a candle till the tallow diffuses a faint smoke, and then
thrusting them into the cold tallow. Rinman long ago defined steel to be
any kind of iron which, when heated to redness, and then plunged in cold
water, becomes harder. But several kinds of cast iron are susceptible of
such hardening. Every malleable and flexible iron, however, which may be
hardened in that way, is a steel. Moreover, steel may be distinguished
from pure iron by its giving a dark-gray spot when a drop of dilute
nitric acid is let fall on its surface, while iron affords a green one.
Exposed to the air, steel rusts less rapidly than iron; and the more
highly carburetted, the more slowly does it rust, and the blacker is the
spot left by an acid.

After hardening, steel seems to be quite a different body; even its
granular texture becomes coarser or finer according to the degree of
heat to which it was raised; it grows so hard as to scratch glass, and
resist the keenest file, while it turns exceedingly brittle. When a
slowly cooled steel rod is forged and filed, it becomes capable of
affording agreeable and harmonious sounds by its vibrations; but
hard-tempered steel affords only dull deafened tones, like those emitted
by a cracked instrument.

The good quality of steel is shown by its being homogeneous; being
easily worked at the forge; by its hardening and tempering well; by its
resisting or overcoming forces; and by its elasticity. To ascertain the
first point, the surface should be ground and polished on the wheel;
when its lustre and texture will appear. The second test requires a
skilful workman to give it a heat suitable to its nature and state of
conversion. The size and colour of the grain are best shown by taking a
bar forged into a razor form; hardening and tempering it; and then
breaking off the thin edge in successive bits with a hammer and anvil.
If it had been fully ignited only at the end, then, after the hardening,
it will display, on fracture, a succession in the aspect of its grains
from that extremity to the other; as they are whiter and larger at the
former than the latter. The other qualities become manifest on filing
the steel; using it as a chisel for cutting iron; or bending it under a
heavy weight.

Much interest was excited a few years back by the experiments of Messrs.
Stodart and Faraday on the alloys of steel with silver, platinum,
rhodium, and iridium. Steel refuses to take up in fusion more than one
five-hundreth part of silver; but with this minute quantity of alloy, it
is said to bear a harder temper, without losing its tenacity. When pure
iron is substituted for steel, the alloys so formed are much less
subject to oxidation in damp air than before. With three _per cent._ of
iridium and osmium, an alloy was obtained which had the property of
tempering like steel, and of remaining clean and bright, in
circumstances when simple iron became covered with rust. “Upon the
whole,” says the editor of the Quarterly Journal of Science, giving a
report of these experiments in his 14th volume, p. 378, “though we
consider these researches upon the alloys of steel as very interesting,
we are not sanguine as to their important influence upon the improvement
of the manufacture of cutlery, and suspect that a bar of the best
ordinary steel, selected with precaution, and most carefully forged,
wrought, and tempered, _under the immediate inspection of the master_,
would afford cutting instruments as perfect and excellent as those
composed of wootz, or of the alloys.”

_Case-hardening_ of iron, is a process for converting a thin film of the
outer surface into steel, while the interior remains as before. Fine
keys are generally finished in this way. See CASE-HARDENING.

So great is the affinity of iron for carbon, that, in certain
circumstances, it will absorb it from carburetted hydrogen, or coal-gas,
and thus become converted into steel. On this principle, Mr. Macintosh
of Glasgow obtained a patent for making steel. His furnace consists of
one cylinder of bricks built concentrically within another. The bars of
iron are suspended in the innermost, from the top; a stream of purified
coal-gas circulates freely round them, entering below and escaping
slowly above, while the bars are maintained in a state of bright
ignition by a fire burning in the annular space between the cylinders.
The steel so produced is of excellent quality; but the process does not
seem to be so economical as the ordinary cementation with charcoal
powder.

_Damasking of steel_, is the art of giving to sabre blades a variety of
figures in the style of watering. See DAMASCUS BLADES.

Several explanations have been offered of the change in the constitution
of steel, which accompanies the tempering operation; but none of them
seems quite satisfactory. It seems to be probable that the ultimate
molecules are thrown by the sudden cooling into a constrained state, so
that their poles are not allowed to take the position of strongest
attraction and greatest proximity; and hence the mass becomes hard,
brittle, and somewhat less dense. An analogous condition may be justly
imputed to hastily cooled glass, which, like hardened steel, requires to
be annealed by a subsequent nicely graduated heat, under the influence
of which the particles assume the position of repose, and constitute a
denser, softer, and more tenacious body. The more sudden the cooling of
ignited steel, the more unnatural and constrained will be the
distribution of its particles, and also the more refractory, an effect
produced by plunging it into cold mercury. This excess of hardness is
removed in any required degree by judicious annealing or tempering. The
state of the carbon present in the steel may also be modified by the
rate of refrigeration, as Mr. Karsten and M. Bréant conceive happens
with cast iron and the damask metal. If the uniform distribution and
combination of the carbon through the mass, determine the peculiarity of
white cast iron, which is a hard and brittle substance, and if its
transition to the dark-gray and softer cast metal be effected by a
partial formation of plumbago during slow cooling, why may not something
similar be supposed to occur with steel, an analogous compound?

Mr. Oldham, printing engineer of the Bank of England, who has had great
experience in the treatment of steel for dies and mills, says that, for
hardening it, the fire should never be heated above the redness of
sealing-wax, and kept at that pitch for a sufficient time. On taking it
out, he hardens it by plunging it, not in water, but in olive oil, or
rather naphtha, previously heated to 200° F. It is kept immersed only
till the ebullition ceases, then instantly transferred into cold spring
water, and kept there till quite cold. By this treatment the tools come
out perfectly clean, and as hard as it is possible to make cast-steel,
while they are perfectly free from cracks, flaws, or twist. Large tools
are readily brought down in temper by being suspended in the red-hot
muffle till they show a straw-colour; but for small tools, he prefers
plunging them in the oil heated to 400 degrees; and leaves them in till
they become cold.

Mr. Oldham softens his steel dies by exposing them to ignition for the
requisite time, imbedded in a mixture of chalk and charcoal.

“The common mode of softening steel,” says Mr. Baynes, “is to put it
into an iron case, surrounded with a paste made of lime, cow’s gall, and
a little nitre and water; then to expose the case to a slow fire, which
is gradually increased to a considerable heat, and afterwards allowed to
go out, when the steel is found to be soft and ready for the
engraver.”[60]

  [60] History of the Cotton Manufacture, p. 269. If that strange
  farrago be employed by Mr. Locket of Manchester, for softening his
  dies and mills, it deserves consideration. Should the nitre be used in
  too great quantity to be all carbonated by the gall, its oxygen may
  serve to consume some of the carbon of the steel, and thus bring it
  nearer to iron. The recipe may be old, but it is a novelty to me.

_Indian steel, or wootz._--The wootz ore consists of the magnetic oxide
of iron, united with quartz, in proportions which do not seem to differ
much, being generally about 42 of quartz and 58 of magnetic oxide. Its
grains are of various size, down to a sandy texture. The natives prepare
it for smelting by pounding the ore, and winnowing away the stony
matrix, a task at which the Hindoo females are very dexterous. The
manner in which iron ore is smelted and converted into wootz or Indian
steel, by the natives at the present day, is probably the very same that
was practised by them at the time of the invasion of Alexander; and it
is a uniform process, from the Himalaya mountains to Cape Comorin. The
furnace or bloomery in which the ore is smelted, is from 4 to 5 feet
high; it is somewhat pear-shaped, being about 2 feet wide at bottom, and
one foot at top; it is built entirely of clay, so that a couple of men
can finish its erection in a few hours, and have it ready for use the
next day. There is an opening in front about a foot or more in height,
which is built up with clay at the commencement, and broken down at the
end, of each smelting operation. The bellows are usually made of a
goat’s skin, which has been stripped from the animal without ripping
open the part covering the belly. The apertures at the legs are tied up,
and a nozzle of bamboo is fastened in the opening formed by the neck.
The orifice of the tail is enlarged and distended by two slips of
bamboo. These are grasped in the hand, and kept close together in making
the stroke for the blast; in the returning stroke they are separated to
admit the air. By working a bellows of this kind with each hand, making
alternate strokes, a pretty uniform blast is produced. The bamboo
nozzles of the bellows are inserted into tubes of clay, which pass into
the furnace at the bottom corners of the temporary wall in front. The
furnace is filled with charcoal, and a lighted coal being introduced
before the nozzles, the mass in the interior is soon kindled. As soon as
this is accomplished, a small portion of the ore, previously moistened
with water, to prevent it from running through the charcoal, but without
any flux whatever, is laid on the top of the coals, and covered with
charcoal to fill up the furnace.

In this manner ore and fuel are supplied; and the bellows are urged for
3 or 4 hours, when the process is stopped; and the temporary wall in
front being broken down, the bloom is removed by a pair of tongs from
the bottom of the furnace. It is then beaten with a wooden mallet, to
separate as much of the scoriæ as possible from it, and, while still
red-hot, it is cut through the middle, but not separated, in order
merely to show the quality of the interior of the mass. In this state it
is sold to the blacksmiths, who make it into bar iron. The proportion of
such iron made by the natives from 100 parts of ore, is about 15 parts.
In converting the iron into steel, the natives cut it into pieces, to
enable it to pack better in the crucible, which is formed of refractory
clay, mixed with a large quantity of charred husk of rice. It is seldom
charged with more than a pound of iron, which is put in with a proper
weight of dried wood chopped small, and both are covered with one or two
green leaves; the proportions being in general 10 parts of iron to 1 of
wood and leaves. The mouth of the crucible is then stopped with a
handful of tempered clay, rammed in very closely, to exclude the air.
The wood preferred is the _Cassia auriculata_, and the leaf that of the
_Asclepias gigantea_, or the _Convolvulus laurifolius_. As soon as the
clay plugs of the crucibles are dry, from 20 to 24 of them are built up
in the form of an arch, in a small blast furnace; they are kept covered
with charcoal, and subjected to heat urged by a blast for about two
hours and a half, when the process is considered to be complete. The
crucibles being now taken out of the furnace and allowed to cool, are
broken, and the steel is found in the form of a cake, rounded by the
bottom of the crucible. When the fusion has been perfect, the top of the
cake is covered with striæ, radiating from the centre, and is free from
holes and rough projections; but if the fusion has been imperfect, the
surface of the cake has a honeycomb appearance, with projecting lumps of
malleable iron. On an average, four out of five cakes are more or less
defective. These imperfections have been tried to be corrected in London
by re-melting the cakes, and running them into ingots; but it is
obvious, that when the cakes consist partially of malleable iron and of
unreduced oxide, simple fusion cannot convert them into good steel. When
care is taken, however, to select only such cakes as are perfect, to
re-melt them thoroughly, and tilt them carefully into rods, an article
has been produced which possesses all the requisites of fine steel in an
eminent degree. In the Supplement to the Encyclopædia Britannica,
article _Cutlery_, the late Mr. Stodart, of the Strand, a very competent
judge, has declared “that for the purposes of fine cutlery, it is
infinitely superior to the best English cast steel.”

The natives prepare the cakes for being drawn into bars by annealing
them for several hours in a small charcoal furnace, actuated by bellows;
the current of air being made to play upon the cakes while turned over
before it; whereby a portion of the combined carbon is probably
dissipated, and the steel is softened; without which operation the cakes
would break in the attempt to draw them. They are drawn by a hammer of a
few pounds weight.

The natives weld two pieces of cast steel, by giving to each a sloping
face, jagged all over with a small chisel; then applying them with some
calcined borax between, and tying them together with a wire, they are
brought to a full red heat, and united by a few smart blows of a hammer.

The ordinary bar iron of Sweden and England, when converted by
cementation into steel, exhibits upon its surface numerous small warty
points, but few or no distinct vesicular eruptions; whereas the
Dannemora and the Ulverston steels present, all over the surface of the
bars, well raised blisters, upwards of three-eighths of an inch in
diameter horizontally, but somewhat flattened at top. Iron of an
inferior description, when highly converted in the cementing-chest,
becomes gray on the outer edges of the fracture; while that of Dannemora
acquires a silvery colour and lustre on the edges, with crystalline
facets within. The highly converted steel is used for tools that require
to be made very hard; the slightly converted, for softer and more
elastic articles, such as springs and sword blades.


STEREOTYPE PRINTING, signifies printing by fixed types, or by a cast
typographic plate. This plate is made as follows:--The form, composed in
ordinary types, and containing one, two, three, or more pages, inversely
as the size of the book, being laid flat upon a slab, with the letters
looking upwards, the faces of the types are brushed over with oil, or
preferably, with plumbago (black lead). A heavy brass rectangular frame
of three sides, with bevelled borders, adapted exactly to the size of
the pages, is then laid down upon the chase,[61] to circumscribe three
sides of its typography; but the fourth side, which is one end of the
rectangle, is formed by placing near the types, and over the hollows of
the chase, a single brass bar, having the same inwards sloping bevel as
the other three sides. The complete frame resembles that of a picture,
and serves to define the area and thickness of the cast, which is made
by pouring the pap of Paris plaster into its interior space, up to a
given line on its edges. The plaster mould, which soon sets, or becomes
concrete, is lifted gently off the types, and immediately placed upright
on its edge in one of the cells of a sheet-iron rack mounted within the
cast-iron oven. An able workman will mould ten sheets octavo in a day,
or 160 pages. The moulds are here exposed to air heated to fully 400°
F., and become perfectly dry in the course of two hours. As they are now
friable and porous, they require to be delicately handled. Each mould,
containing generally two pages octavo, is laid, with the impression
downwards, upon a flat cast-iron plate, called the floating-plate; this
plate being itself laid on the bottom of the dipping-pan, which is a
cast-iron square tray, with its upright edges sloping outwards. A
cast-iron lid is applied to the dipping-pan, and secured in its place by
a screw. The pan having been heated to 400° in a cell of the oven, under
the mould-rack, previous to receiving the hot mould, is ready to be
plunged into the bath of melted alloy contained in an iron pot placed
over a furnace, and it is dipped with a slight deviation from the
horizontal plane, in order to facilitate the escape of the air. As there
is a minute space between the back or top surface of the mould and the
lid of the dipping-pan, the liquid metal, on entering into the pan
through the orifices in its corners, floats up the plaster along with
the iron plate on which it had been laid, thence called the
floating-plate, whereby it flows freely into every line of the mould,
through notches cut in its edge, and forms a layer or lamina upon its
face, of a thickness corresponding to the depth of the border. Only a
thin metal film is left upon the back of the mould. The dipping-pan is
suspended, plunged, and removed by means of a powerful crane,
susceptible of vertical and horizontal motions in all directions. When
lifted out of the bath, it is set in a water-cistern, upon bearers so
placed as to allow its bottom only to touch the surface. Thus the metal
first concretes below, while, by remaining fluid above, it continues to
impart hydrostatic pressure during the shrinkage attendant upon
refrigeration. As it thus progressively contracts in volume, more melted
metal is fed into the corners of the pan by a ladle, in order to keep up
the hydrostatic pressure upon the mould, and to secure a perfect
impression, as well as a solid cast. Were the pan more slowly and
equably cooled, by being left in the air, the thin film of metal upon
the back of the inverted plaster cake would be apt to solidify first,
and intercept the hydrostatic action indispensable to the purpose of
filling all the lines in its face. A skilful workman makes five dips,
containing two pages octavo each, in the course of an hour, or about
nine and a half octavo sheets per day. The pan being taken asunder, the
compound cake of mould and metal is removed, and beat upon its edges
with a wooden mallet, to detach the superfluous metal. The stereotype
plate is then handed over to the picker, who planes its edges truly
square, turns its back flat upon a lathe to a determinate thickness, and
carefully removes the little imperfections occasioned by dirt or air
left among the letters when the mould was cast. Should any of them be
damaged in the course of the operation, they must be cut out, and
replaced by soldering in separate types of the same size and form.

  [61] Chase (_chassis_, frame, Fr.), quoin (_coin_, wedge, Fr.), are
  terms which show that the art of printing came directly from France to
  England.


STILL (_Alambic_, Fr.; _Blase_, Germ.); is a chemical apparatus, for
vaporizing liquids by heat in one part, called the _cucurbit_, and
condensing the vapours into liquids in another part, called the
_refrigeratory_; the general purpose of both combined being to separate
the more volatile fluid particles from the less volatile. In its
simplest form, it consists of a retort and a receiver, or of a
pear-shaped matrass and a capital, furnished with a slanting tube for
conducting away the condensed vapours in drops; whence the term _still_,
from the Latin verb _stillare_, to drop. Its chief employment in this
country being to eliminate alcohol, of greater or less strength, from
fermented wash, I shall devote this article to a description of the
stills best adapted to the manufacture of British spirits, referring to
chemical authors[62] for those fitted for peculiar objects.

  [62] The treatises of Le Normand and Dubrunfaut may also be consulted.
  The French stills are in general so much complicated with a great many
  small pipes and passages, as to be unfit for distilling the glutinous
  wash of grains.

In respect of rapidity and extent of work, stills had attained to an
extraordinary pitch of perfection in Scotland about thirty years ago,
when legislative wisdom thought fit to levy the spirits duty, per annum,
from each distiller, according to the capacity of his still. It having
been shown, in a report presented to the House of Commons in 1799, that
an 80-gallon still could be worked off in eight minutes, this fact was
made the basis of a new fiscal law, on the supposition that the maximum
of velocity had been reached. But, instigated by the hopes of enormous
gains at the expense of the revenue, the distillers soon contrived to do
the same thing in three minutes, by means of broad-bottomed shallow
stills, with stirring-chains, and lofty capitals. In the year 1815, that
preposterous law, which encouraged fraud and deteriorated the
manufacture, was repealed. The whiskey duties having been since levied,
independently of the capacity of the still, upon the quantity produced,
such rapid operations have been abandoned, and processes of economy in
fuel, and purity in product, have been sought after.

One of the greatest improvements in modern distilleries, is completing
the analysis of crude spirit at one operation. Chemists had been long
familiar with the contrivance of Woulfe, for impregnating with gaseous
matter, water contained in a range of bottles; but they had not thought
of applying that plan to distillation, when Edouard Adam, an illiterate
workman of Montpellier, after hearing accidentally a chemical lecture
upon that apparatus, bethought himself of converting it into a still. He
caused the boiling-hot vapours to chase the spirits successively out of
one bottle into another, so as to obtain in the successive vessels
alcohol of any desired strength and purity, “_at one and the same
heat_.” He obtained a patent for this invention in 1801, and was soon
afterwards enabled, by his success on the small scale, to set up in his
native city a magnificent distillery, which excited the admiration of
all the practical chemists of that day. In November, 1805, he obtained a
certificate of certain improvements for extracting from wine, at one
process, the whole of its alcohol. Adam was so overjoyed, after making
his first experiments, that he ran about the streets of Montpellier,
telling every body of the surprising results of his invention. Several
competitors soon entered the lists with him, especially Solimani,
professor of chemistry in that city, and Isaac Berard, distiller in the
department of Gard; who, having contrived other forms of continuous
stills, divided the profits with the first inventor.

The principles of spirituous distillation may be stated as follows:--The
boiling point of alcohol varies with its density or strength, in
conformity with the numbers in the following table:--

  +--------+-------------------+
  |Specific| Boiling point, by |
  |gravity.|Fahrenheit’s scale.|
  +--------+-------------------+
  | 0·7939 |       168·5°      |
  | 0·8034 |       168·0       |
  | 0·8118 |       168·5       |
  | 0·8194 |       169·0       |
  | 0·8265 |       172·5       |
  | 0·8332 |       173·5       |
  | 0·8397 |       175·0       |
  | 0·8458 |       177·0       |
  | 0·8518 |       179·0       |
  | 0·8875 |       181·0       |
  | 0·8631 |       183·0       |
  | 0·8765 |       187·0       |
  | 0·8892 |       190·0       |
  | 0·9013 |       194·0       |
  | 0·9126 |       197·0       |
  | 0·9234 |       199·0       |
  | 0·9335 |       201·0       |
  +--------+-------------------+

See also the table under ALCOHOL, page 16.

Hence, the lower the temperature of the spirituous vapour which enters
the refrigeratory apparatus, the stronger and purer will the condensed
spirit be; because the offensive oils, which are present in the wash or
wine, are less volatile than alcohol, and are brought over chiefly with
the aqueous vapour. A perfect still should, therefore, consist of three
distinct members; first, the cucurbit, or kettle; second, the rectifier,
for intercepting more or less of the watery and oily particles; and
third, the refrigerator, or condenser of the alcoholic vapours.

These principles are illustrated in the construction of the still
represented in _figs._ 1057, 1058, 1059, 1060, 1061.; in which the
resources of the most refined French stills are combined with a
simplicity and solidity suited to the grain distilleries of the United
Kingdom. Three principal objects are obtained by the arrangement here
shown; first, the extraction from fermented wort or wine, at one
operation, of a spirit of any desired cleanness and strength; second,
great economy of time, labour, and fuel; third, freedom from all danger
of blowing up or boiling over, by mismanaged firing. When a combination
of water, alcohol, and essential oil, in the state of vapour, is passed
upwards through a series of winding passages, maintained at a
determinate degree of heat, between 170° and 180°, the alcohol alone, in
any notable proportion, will retain the elastic form, and will proceed
onwards into the refrigeratory tube, in which the said passages
terminate; while the water and the oil will be in a great measure
condensed, arrested, and thrown back into the body of the still, to be
discharged with the effete residuum.

The system of passages or channels, represented in _fig._ 1058., is so
contrived as to bring the mingled vapours which rise from the alembic
_a_, into ample and intimate contact with metallic surfaces, maintained,
in a water-bath, at a temperature self-regulated by a heat-governor. See
THERMOSTAT.

[Illustration: 1057 1058 1059 1060 1061]

The neck of the alembic tapers upwards, as shown at _b_, _fig._ 1057.;
and at _c_, _fig._ 1058., it enters the bottom, or ingress vestibule, of
the rectifier _c_, _f_. _f_ is its top or egress vestibule, which
communicates with the bottom one by parallel cases or rectangular
channels _d_, _d_, _d_, of which the width is small, compared with the
length and height. These cases are open at top and bottom, where they
are soldered or riveted into a general frame within the cavity, enclosed
by the two covers _f_, _c_, which are secured round their edges _e_,
_e_, _e_, _e_, with bolts and packing. Each case is occupied with a
numerous series of shelves or trays, placed at small distances over each
other, in a horizontal or slightly inclined position, of which a side
view is given in _fig._ 1059., and cross sections at _d_, _d_, _d_,
_fig._ 1058. Each shelf is turned up a little at the two edges, and at
one end, but sloped down at the other end, that the liquor admitted at
the top may be made to flow slowly backwards and forwards in its descent
through the system of shelves or trays, as indicated by the darts and
spouts in _fig._ 1059. The shelves of each case are framed together by
two or more vertical metallic rods, which pass down through them, and
are fixed to each shelf by solder, or by screw-nuts. By this means, if
the cover _f_, be removed, the sets of shelves may be readily lifted out
of the cases and cleaned; for which reason they are called _movable_.

The intervals _i_, _i_, _i_, _fig._ 1058., between the cases, are left
for the free circulation of the water contained in the bath-vessel _g_,
_g_; these intervals being considerably narrower than the cases.

_Fig._ 1060. represents in plan the surface of the rectifying cistern,
shown in two different sections in _figs._ 1058. and 1059. _h_, _k_,
_figs._ 1058. and 1060., is the heat-governor, shaped somewhat like a
pair of tongs. Each leg is a compound bar, consisting of a flat bar or
ruler of steel, and one of brass alloy, riveted facewise together,
having their edges up and down. The links, at _k_, are joined to the
free ends of these compound bars, which, receding by increase and
approaching by decrease of temperature, act by a lever on the stopcock
_l_, fixed to the pipe of a cold-water back, and are so adjusted by a
screw-nut, that whenever the water in the bath vessel _g_, _g_, rises
above the desired temperature, cold water will be admitted, through the
stopcock _l_, and pipe _n_, into the bottom of the cistern, and will
displace the over-heated water by the overflow-pipe _m_. Thus a perfect
equilibrium of caloric may be maintained, and alcoholic vapour of
correspondent uniformity transmitted to the refrigeratory.

_Fig._ 1061. is the cold condenser, of similar construction to the
rectifier, _fig._ 1058.; only the water cells should be here larger in
proportion to the vapour channels _d_, _d_. This refrigeratory system
will be found very powerful, and it presents the great advantage of
permitting its interior to be readily inspected and cleansed. It is best
made of laminated tin, hardened with a little copper alloy.

The mode of working the preceding apparatus will be understood by the
following instructions. Into the alembic, _a_, let as much fermented
liquor be admitted as will protect its bottom from being injured by the
fire, reserving the main body in the charging-back. Whenever the
ebullition in the alembic has raised the temperature of the water-bath
_g_, _g_, to the desired pitch, whether that be 170°, 175°, or 180°, the
thermostatic instrument is to be adjusted by its screw-nut, and then the
communication with the charging-back is to be opened by moving the index
of the stopcock o, over a proper portion of its quadrantal arch. The
wash will now descend in a slender equable stream, through the pipe _o_,
_f_, thence spread into the horizontal tube _p_, _p_, and issue from the
orifices of distribution, as seen in the figure, into the respective
flat trays or spouts. The manner of its progress is seen for one set of
trays, in _fig._ 1059. The direction of the stream in each shelf is
evidently the reverse of that in the shelf above and below it; the
turned-up end of one shelf corresponding to the discharge slope of its
neighbour.

By diffusing the cool wash or wine in a thin film over such an ample
range of surfaces, the constant tendency of the bath to exceed the
proper limit of temperature is counteracted to the utmost, without waste
of time or fuel; for the wash itself, _in transitu_, becomes
boiling-hot, and experiences a powerful steam distillation. By this
arrangement a very moderate influx of cold water, through the
thermostatic stopcock, suffices to temper the bath; such an extensive
vaporization of the wash producing a far more powerful refrigerant
influence than its simple heating to ebullition. It deserves to be
remarked, that the maximum distillatory effect, or the bringing over the
greatest quantity of pure spirits in the least time, and with the least
labour and fuel, is here accomplished without the least steam pressure
in the alembic; for the passages are all pervious to the vapour;
whereas, in almost every wash-still heretofore contrived for similar
purposes, the spirituous vapours must force their way through successive
layers of liquid, the total pressure produced by which causes undue
elevation of temperature, and obstruction to the process. Whatever
supplementary refrigeration of the vapours in their passage through the
bath may be deemed proper, will be administered by the thermostatic
regulator.

Towards the end of the process, after all the wash has entered the
alembic, it may be sometimes desirable, for the sake of despatch, to
modify the thermostat, by its adjusting-screw, so that the bath may take
a higher temperature, and allow the residuary feints to run rapidly
over, into a separate cistern. This weak fluid may be pumped back into
the alembic, as the preliminary charge of a fresh operation.

The above plan of a water-bath regulated by the thermostat, may be used
simply as a rectifying cistern, without transmitting the spirit or wash
down through it. The series of shelves will cause the vapours from the
still to impinge against a most extensive system of metallic surfaces,
maintained at a steady temperature, whereby their watery and crude
constituents will be condensed and thrown back, while their fine
alcoholic particles will proceed forwards to the refrigeratory. Any
ordinary still may be readily converted into this self-rectifying form,
by merely interposing the cistern, _fig._ 1058., between the alembic and
the worm-tub. The leading novelty of the present invention is the
_movable_ system of shelves or trays, enclosed in metallic cases,
separated by water, combined with the thermostatic regulator. By this
combination, any quality of spirits may be procured at one step from
wash or wine, by an apparatus, simple, strong and easily kept in order.

The empyreumatic taint which spirits are apt to contract from the action
of the naked fire on the bottom of the still, may be entirely prevented
by the use of a bath of potash lye, _p_, _p_, _fig._ 1057.; for thus a
safe and effectual range of temperature, of 300° F., may be conveniently
obtained. The still may also be used without the bath vessel.

[Illustration: 1062]

Mr. D. T. Shears, of Southwark, obtained a patent in March, 1830, for
certain improvements and additions to stills, which are ingenious. They
are founded upon a previous patent, granted to Joseph Corty, in 1818; a
section of whose contrivance is shown in _fig._ 1062., consisting of a
first still _a_, a second still _b_, a connecting tube _c_, from the one
end to the other, and the tube _d_, which leads from the second
still-head down through the bent tube _e_, _e_, to the lower part of the
condensing apparatus.

The original improvements described under Corty’s patent, consisted
further, in placing boxes _f_, _f_, _f_, of the condensing apparatus in
horizontal positions, and at a distance from each other, in order that
the vapour might ascend through them, for the purpose of discharging the
spirit by the top tube _g_, and pipe _h_, into the worm, in a highly
rectified or concentrated state. In each of the boxes _f_, there is a
convex plate or inverted dish _i_, _i_, _i_, and the vapour in rising
from the tube _e_, strikes against the concave or under part of the
first dish, and then escapes round its edges, and over its convex
surface, to the under part of the second dish, and so on to the top, the
condensed part of the vapour flowing down again into the still, and the
spirit passing off by the pipe _h_, at top; and as the process of
condensation will be assisted by cooling the vapour as it rises, cold
water is made to flow over the tops of the boxes _f_, from a cock _k_,
and through small channels or tubes on the sides of the boxes, and is
ultimately discharged by the pipe _l_, at bottom.

[Illustration: 1063]

_Fig._ 1063. represents a peculiarly shaped tube _a_, through which the
spirit is described as passing after leaving the end of the worm at _b_,
which tube is open to the atmospheric air at _z_; _c_, is the passage
through which the carbonic acid gas is described as escaping into the
vessel of water _d_.

[Illustration: 1064 1065]

Now the improvements claimed under the present patent, are exhibited in
_figs._ 1064, 1065, and 1066. _Fig._ 1064. represents the external
appearance of a still, the head of which is made very capacious, to
guard against over-boiling by any mismanagement of the fire; _fig._
1065. is the same, partly in section. On the top of the still-head is
formed the first-described rectifying apparatus, or series of condensing
boxes. The vapour from the body of the still filling the head, meets
with the first check from the dish or lower vessel _i_, and after
passing under its edges, ascends and strikes against the lower part of
the second dish or vessel _i_, and so on, till it ultimately leaves the
still-head by the pipe at top.

This part of the apparatus is slightly altered from the former, by the
substitution of hollow convex vessels, instead of the inverted dishes
before described, which vessels have rims descending from their under
surfaces, for the purpose of retaining the vapour. The cold water,
which, as above described, flowed over the tops of the boxes _f_, for
the purpose of cooling them, now flows also through the hollow convex
vessels _i_, within the boxes, and by that means greatly assists the
refrigerating process, by which the aqueous parts of the vapour are more
readily condensed, and made to fall down and flow back again into the
body of the still, while the spirituous parts pass off at top to the
worm, in a very high state of rectification.

After the water employed for the refrigeration has passed over all the
boxes, and through all the vessels, it is carried off by the pipe _m_,
through the vessel _n_, called the wash-heater; that is, the vessel in
which the wash is placed previous to introducing it into the still. The
pipe _m_, is coiled round in the lower part of the vessel _n_, in order
that the heated water may communicate its caloric to the wash, instead
of losing the heat by allowing the water to flow away. After the heated
water has made several turns round the wash heater, it passes out at the
curved pipe _o_, which is bent up, in order to keep the coils of the
pipe within always full of water.

Instead of the coiled pipe _n_, last described, the patentee proposes
sometimes to pass the hot water into a chamber in a tub or wooden
vessel, as at _n_, in _fig._ 1061., in which the wash to be heated
occupies the upper part of the vessel, and is separated from the lower
part by a thin metallic partition.

The swan-neck _h_, _figs._ 1064. and 1065., which leads from the head of
the still, conducts the spirit from the still through the wash-heater,
where it becomes partially cooled, and gives out its heat to the wash;
and from thence the spirit passes to the worm tub, and being finally
condensed, is passed through a safety tube, as (_fig._ 1058.) before
described, and by the funnel is conducted into the cask below.

[Illustration: 1066 1067]

Should any spirit rise in the wash-heater during the above operation, it
will be carried down to the worm by the neck _p_, and coiled pipe, and
discharged at its lower end; or it may be passed into the still-head, as
shown in _fig._ 1062.

A patent was obtained by Mr. Æneas Coffey, in August, 1830, for a still,
which has been since mounted in several distilleries. It is economical
in fuel, labour, and time, but is said not to produce a clean spirit,
without peculiar attention.

The apparatus is represented in _fig._ 1067. _a_, _b_, _c_, _d_, is a
sectional view of that part of the still wherein the wash is deprived of
its alcohol, and the vapours analyzed. It is described as consisting of
a chamber or vessel _a_, with the vertical chamber _b_, _c_, placed
above it; the lower half of this chamber is divided into compartments by
horizontal plates _e_, _e_, _e_, of thin copper or other metal; each of
these plates is turned down at one side, until it nearly touches the
plate next underneath it, as shown in the figure; thus leaving a passage
throughout the whole of them, by which any liquid falling on the top
plate may descend into the next under it, and from that to the third,
and so on, from plate to plate, at the alternate ends, until it arrives
at the last plate, wherein it falls into the vessel _a_, by the pipe
_f_; each of these plates is furnished with several light valves,
opening upwards, through which any steam or vapour may ascend; it may
also be perforated with holes, but they must not be so numerous or so
large as to allow of all the steam passing through them without raising
the valves; _c_, is a pipe by which the alcoholic vapour, after it has
been analyzed, and has acquired the proper strength, is conducted into
the vessel _d_, which is made perfectly close; the vapour will here be
condensed on the surface of the pipe _g_, _g_, _g_; from this chamber it
will descend in a liquid state into the pipe _h_, whence it may be
conducted to a worm or refrigerator, to be cooled in the ordinary way;
_i_, is a vessel through which the spent wash flows, after being
operated upon in the distilling apparatus, and is discharged in a state
of ebullition; _j_, is a vessel or chamber containing the wash to be
distilled. A force pump may be substituted, to force the wash through
the pipes _k_, and distilling apparatus, with the velocity required.

The patentee states that it is requisite the wash should be passed
through the pipe _k_, with sufficient velocity and force, so as to
prevent the deposition of sediment in the pipe; the wash in its passage
through the pipe _k_, will gradually become increased in temperature as
it passes through the spent wash in the chamber, and the close vessel
_d_, until it is discharged nearly at the boiling point on the upper
plate in the chamber, where it comes in contact with the vapours arising
from the vessel _a_.

It is to be observed, that the wort does not reach the boiling point
while in the pipe _k_, _k_; to ascertain which, a thermometer is placed
on the pipe, and by increasing or diminishing the quantity of wash, its
temperature may be regulated. The wash, after being discharged from the
pipe _k_, descends from plate to plate as before mentioned, at which
time a supply of steam from a boiler, or generator is admitted into the
apparatus, through the pipe.

The lower part of this pipe in the vessel _a_, is pierced with a number
of small holes, so as to spread the steam over the vessel; it then rises
upwards, passing through the plate by the small holes and valves, and
through the stratum or sheet of wash flowing over them; the wash, as it
descends, gives out a portion of its alcohol to the steam, as it passes
over every plate, until it is entirely deprived of its spirit, which it
will generally do by the time it arrives at the 7th or 8th plate; but it
is better to employ a greater number, to guard against accidents or
neglect.

A small steam pipe rises from the chamber _a_, with its upper end
opening into the box or chamber; into this chamber the end of a worm
projects from the cistern of cold water; the steam rising up the pipe is
nearly all condensed in the worm, and flows back into the chamber _a_,
by the pipe. The small portion of the steam uncondensed, is allowed to
escape at the upper end of the worm, and the flame of a small lamp or
taper is to be constantly kept over the orifice; when, should the least
quantity of alcohol descend with the wash into the chamber _a_, it will
rise with the steam through the pipe and worm, and immediately take fire
from the flame of the lamp or taper, thereby warning the attendant to
increase the supply of steam or diminish the quantity of wash, as may
seem necessary.

[Illustration: 1068]

I shall conclude this article with a description of the cheap still
which is commonly employed by the chemists in Berlin for rectifying
alcohol. _a_, is the ash-pit; _b_, the fireplace; _c_, _c_, the flues,
which go spirally round the sides of the cucurbit _d_; _e_, the capital,
made of block tin, and furnished with a brass edge, which fits tight to
a corresponding edge on the mouth of _d_; _f_, _f_, the slanting pipes
of the capital; _g_, the oval refrigeratory, made of copper; _h_, the
water-gauge glass tube; _i_, a stopcock for emptying the vessel; _k_,
do., for drawing off the hot water from the surface; _l_, tube for the
supply of cold water. A double cylinder of tin is placed in the
refrigeratory, of which the outer one _m_, _m_, stands upon three feet,
and is furnished with a discharge pipe _n_. The inner one _o_, _o_,
which is open above, receives cold water through the pipe _p_, and lets
the warm water flow off through the short tube _q_, into the
refrigeratory. In the narrow space between the two cylinders, the
vapours proceeding from the capital are condensed, and pass off in the
liquid state through _n_. The refrigeratory is made oval, in order to
receive two condensers alongside of each other in the line of the longer
axis; though only one, and that in the middle, is represented in the
figure.


STOCKING MANUFACTURE. See HOSIERY.


STONE, is earthy matter, condensed into so hard a state as to yield only
to the blows of a hammer, and therefore well adapted to the purposes of
building. Such was the care of the antients to provide strong and
durable materials for their public edifices, that but for the desolating
hands of modern barbarians, in peace and in war, most of the temples and
other public monuments of Greece and of Rome would have remained perfect
at the present day, uninjured by the elements during 2000 years. The
contrast, in this respect, of the works of modern architects, especially
in Great Britain, is very humiliating to those who boast so loudly of
social advancement; for there is scarcely a public building of recent
date, which will be in existence one thousand years hence. Many of the
most splendid works of modern architecture are hastening to decay, in
what may be justly called the very infancy of their existence, if
compared with the date of those erected in antient Italy, Greece, and
Egypt. This is remarkably the case with the three bridges of London,
Westminster, and Blackfriars; the foundations of which began to perish
most visibly in the very lifetime of their constructors. Every stone
intended for a durable edifice, ought to be tested as to its durability,
by immersion in a saturated solution of sulphate of soda, and exposure
during some days to the air. The crystallization which ensues in its
interior, will cause the same disintegration of its substance which
frost would occasion in a series of years.

[Illustration: 1069 1070 1071 1072]


STONE, ARTIFICIAL, for statuary and other decorations of architecture,
has been made for several years with singular success at Berlin, by Mr.
Feilner. His materials are nearly the same with those of English
pottery; and the plastic mass is fashioned either in moulds, or by hand.
His kilns, which are peculiar in form, and economical in fuel, deserve
to be generally known. _Figs._ 1069. and 1070. represent his round kiln;
_fig._ 1069. being an oblique section in the line A, B, C, of _fig._
1070., which is a ground plan in the line D, _a_, _b_, E, of _fig._
1069. The inner circular space _c_, covered with the elliptical arch, is
filled with the figures to be baked, set upon brick supports. The hearth
is a few feet above the ground; and there are steps before the door _d_,
for the workmen to mount by, in charging the kiln. The fire is applied
on the four sides under the hearth. The flame of each passes along the
straight flues _f i_, _f i_, and _f k_. In the second annular flue _g_,
_g_, as also in the third _l_, _l_, the flame of each fire is kept
apart, being separated from the adjoining, by the stones _h_ and _m_. In
the fourth flue _n_, the flames again come together, as also in _o_, and
ascend by the middle opening. Besides this large orifice, there are
several small holes, _p_, _p_, in the hearth over the above flues, to
lead the flames from the other points into contact with the various
articles. There are also channels _q_, _q_, in the sides, enclosed by
thin walls _r_, to promote the equable distribution of the heat; and
these are placed right over the first fire-flues _e_. The partitions
_r_, are perforated with many holes, through which, as well as from
their tops, the flame may be directed inwards and downwards; _s_ are the
vents for carrying off the flames into the upper space _u_, which is
usually left empty. These vents can be closed by iron damper-plates,
pushed in through the side-slits of the dome. _t_, _t_, are peep-holes,
for observing the state of ignition in the furnace; but they are most
commonly bricked up. _Fig._ 1071. is a vertical section, and _fig._
1072. a plan, of an excellent kiln for baking clay to a stony
consistence, for the above purpose, or for burning fire-bricks. A, is
the lower; B, the middle; C, the upper kiln; and D, the hood,
terminating in the chimney E. _a_, _a_, is the ash-pit; _b_, _b_, the
vault for raking out the ashes; it is covered with an iron door _c_.
_d_, is the peep-hole, filled with a clay stopper; _e_, is the
fireplace; _f_, _f_, a vent in the middle of each arch; _g_, _g_, flues
at the sides of the arches, situated between the two fireplaces; _h_,
_i_, _k_, are apertures for introducing the articles to be baked; _l_, a
grate for the fire in the uppermost kiln; _m_, the ash-pit; _n_, the
fire-door; _o_, openings through which the flames of a second fire are
thrown in. At first, only the ground kiln A, is fired, with cleft
billets of pine-wood, introduced at the opening _e_; when this is
finished, the second is fired; and then the third, in like manner. This
kiln is very like the porcelain kiln of Sèvres, and is employed in many
places for baking stoneware.

Mr. Keene obtained a patent, about a year ago, for making a factitious
stone-paste in the following way:--He dissolves one pound of alum in a
gallon of water, and in this solution he soaks 84 pounds of gypsum
calcined in small lumps. He exposes these lumps in the open air for
about eight days, till they become apparently dry, and then calcines
them in an oven at a dull-red heat. The waste heat of a coke oven is
well adapted for this purpose. (See PITCOAL, COKING OF.) These lumps,
being ground and sifted, afford a fine powder, which, when made up into
a paste with the proper quantity of water, forms the petrifying ground.
The mass soon concretes, and after being brushed over with a thin layer
of the petrifying paste, may be polished with pumice, &c., in the usual
way. It then affords a body of great compactness and durability. If half
a pound of copperas be added to the solution of the alum, the gypsum
paste, treated as above, has a fine cream or yellow colour. This stone
stands the weather well.


STONEWARE. (_Fayence_, Fr.; _Steingut_, Germ.) See POTTERY.


STORAX, STYRAX, flows from the twigs and the trunk of the _Liquidambar
styraciflua_, a tree which grows in Louisiana, Virginia, and Mexico.
Liquidamber, as this resin is also called, is a brown or ash-gray
substance, of the consistence of turpentine, which dries up rapidly, has
an agreeable smell, like benzoin, and a bitterish, sharp, burning taste.
It dissolves in four parts of alcohol, and affords 1·4 per cent. of
benzoic acid.


STOVE (_Poële_, _Calorifère_, Fr.; _Ofen_, Germ.); is a fireplace, more
or less close, for warming apartments. When it allows the burning coals
to be seen, it is called a stove-grate. Hitherto stoves have rarely been
had recourse to in this country for heating our sitting-rooms; the
cheerful blaze and ventilation of an open fire being generally
preferred. But last winter, by its inclemency, gave birth to a vast
multitude of projects for increasing warmth and economizing fuel, many
of them eminently insalubrious, by preventing due renewal of the air,
and by the introduction of noxious fumes into it. When coke is burned
very slowly in an iron box, the carbonic acid gas which is generated,
being half as heavy again as the atmospherical air, cannot ascend in the
chimney at the temperature of 300° F.; but regurgitates into the
apartment through every pore of the stove, and poisons the atmosphere.
The large stoneware stoves of France and Germany are free from this
vice; because, being fed with fuel from the outside, they cannot produce
a reflux of carbonic acid into the apartment, when their draught becomes
feeble, as inevitably results from the obscurely burning stoves which
have the doors of the fireplace and ash-pit immediately above the
hearth-stone.

I have recently performed some careful experiments upon this subject,
and find that when the fuel is burning so slowly in the stove as not to
heat the iron surface above the 250th or 300th degree of Fahr., there is
a constant deflux of carbonic acid gas from the ash-pit into the room.
This noxious emanation is most easily evinced by applying the beak of a
matrass, containing a little Goulard’s extract (solution of subacetate
of lead), to a round hole in the door of the ash-pit of a stove in this
languid state of combustion. In a few seconds the liquid will become
milky, by the reception of carbonic acid gas. I shall be happy to afford
ocular demonstration of this fact to any incredulous votary of the
pseudo-economical, anti-ventilation, stoves now so much in vogue. There
is no mode in which the health and life of a person can be placed in
more insidious jeopardy, than by sitting in a room with its chimney
closed up with such a choke-damp-vomiting stove.

That fuel may be consumed by an obscure species of combustion, with the
emission of very little heat, was clearly shown in Sir H. Davy’s
_Researches on Flame_. “The facts detailed on insensible combustion,”
says he, “explain why so much more heat is obtained from fuel when it is
burned quickly, than slowly; and they show that, in all cases, the
temperature of the acting bodies should be kept as high as possible; not
only because the general increment of heat is greater, but likewise
because those combinations are prevented, which, at lower temperatures,
take place without any considerable production of heat. These facts
likewise indicate the source of the great error into which experimenters
have fallen, in estimating the heat given out in the combustion of
charcoal; and they indicate methods by which the temperature may be
increased, and the limits to certain methods.” These conclusions are
placed in a strong practical light by the following simple
experiments:--I set upon the top orifice of a small cylindrical stove, a
hemispherical copper pan, containing six pounds of water, at 60° F., and
burned briskly under it 3-1/2 pounds of coke in an hour; at the end of
which time, 4-1/2 pounds of water were boiled off. On burning the same
weight of coke _slowly_ in the same furnace, surmounted by the same pan,
in the course of 12 hours, little more than one-half the quantity of
water was exhaled. Yet, in the first case, the aerial products of
combustion swept so rapidly over the bottom of the pan, as to
communicate to it not more than one-fourth of the effective heat which
might have been obtained by one of the plans described in the article
EVAPORATION; while, in the second case, these products moved at least 12
times more slowly across the bottom of the pan, and ought therefore to
have been so much the more effective in evaporation, had they possessed
the same power or quantity of heat.

[Illustration: 1073]

Stoves, when properly constructed, may be employed both safely and
advantageously to heat entrance-halls upon the ground story of a house;
but care should be taken not to vitiate the air by passing it over
ignited surfaces, as is the case with most of the patent stoves now
foisted upon the public. _Fig._ 1073. exhibits a vertical section of a
stove which has been recommended for power and economy; but it is highly
objectionable, as being apt to scorch the air. The flame of the fire A,
circulates round the horizontal pipes of cast iron, _b b_, _c c_, _d d_,
_e e_, which receive the external air at the orifice _b_, and conduct it
up through the series, till it issues highly heated at K, L, and may be
thence conducted wherever it is wanted. The smoke escapes through the
chimney B. This stove has evidently two prominent faults; first, it
heats the air-pipes very unequally, and the undermost far too much;
secondly, the air, by the time it has ascended through the zigzag range
to the pipe _e e_, will be nearly of the same temperature with it, and
will therefore abstract none of its heat. Thus the upper pipes, if there
be several in the range, will be quite inoperative, wasting their warmth
upon the sooty air.

[Illustration: 1074]

_Fig._ 1074. exhibits a transverse vertical section of a far more
economical and powerful stove, in which the above evils are avoided. The
products of combustion of the fire A, rise up between two brick walls,
so as to play upon the bed of tiles B, where, after communicating a
moderate heat to the series of slanting pipes whose areas are
represented by the small circles _a_, _a_, they turn to the right and
left, and circulate round the successive rows of pipes _b b_, _c c_, _d
d_, _e e_, and finally escape at the bottom by the flues _g_, _g_,
pursuing a somewhat similar path to that of the burned air among a bench
of gas-light retorts. It is known, that two-thirds of the fuel have been
saved in the gas-works by this distribution of the furnace. For the
purpose of heating apartments, the great object is to supply a vast body
of genial air; and, therefore, merely such a moderate fire should be
kept up in A, as will suffice to warm all the pipes pretty equably to
the temperature of 220° Fahr.; and, indeed, as they are laid with a
slight slope, are open to the air at their under ends, and terminate at
the upper in a common main pipe or tunnel, they can hardly be rendered
very hot by any intemperance of firing. I can safely recommend this
stove to my readers. If the tubes be made of stoneware, its construction
will cost very little; and they may be made of any size, and multiplied
so as to carry off the whole effective heat of the fuel, leaving merely
so much of it in the burned air, as to waft it fairly up the chimney.

I shall conclude this article by a short extract of a paper which was
read before the Royal Society, on the 16th of June, 1836, _upon warming
and ventilating apartments_; a subject to which my mind had been
particularly turned at that time, by the Directors of the Customs Fund
of Life Assurance, on account of the very general state of indisposition
and disease prevailing among those of their officers (nearly 100 in
number) engaged on duty in the Long Room of the Custom House, London.

“The symptoms of disorder experienced by the several gentlemen (about
twenty in number), whom I examined, out of a great many who were
indisposed, were of a very uniform character. The following is the
result of my researches:--

“A sense of tension or fulness of the head, with occasional flushings of
the countenance, throbbing of the temples, and vertigo, followed, not
unfrequently, with a confusion of ideas, very disagreeable to officers
occupied with important and sometimes intricate calculations. A few are
affected with unpleasant perspiration on their sides. The whole of them
complain of a remarkable coldness and languor in their extremities, more
especially the legs and feet, which has become habitual, denoting
languid circulation in these parts, which requires to be counteracted by
the application of warm flannels on going to bed. The pulse is, in many
instances, more feeble, frequent, sharp, and irritable, than it ought to
be, according to the natural constitution of the individuals. The
sensations in the head occasionally rise to such a height,
notwithstanding the most temperate regimen of life, as to require
cupping, and at other times depletory remedies. Costiveness, though not
a uniform, is yet a prevailing symptom.

“The sameness of the above ailments, in upwards of one hundred
gentlemen, at very various periods of life, and of various temperaments,
indicates clearly sameness in the cause.

“The temperature of the air in the Long Room ranged, in the three days
of my experimental inquiry, from 62° to 64° of Fahrenheit’s scale; and
in the Examiner’s Room it was about 60°, being kept somewhat lower by
the occasional shutting of the hot-air valve, which is here placed under
the control of the gentlemen; whereas that of the Long Room is designed
to be regulated in the sunk story, by the fireman of the stove, who
seems sufficiently careful to maintain an equable temperature amidst all
the vicissitudes of our winter weather. Upon the 7th of January, the
temperature of the open air was 50°; and on the 11th it was only 35°;
yet upon both days the thermometer in the Long Room indicated the same
heat, of from 62° to 64°.

“The hot air discharged from the two cylindrical stove-tunnels into the
Long Room was at 90° upon the 7th, and at 110° upon the 11th. This air
is diluted, however, and disguised, by admixture with a column of cold
air, before it is allowed to escape. The air, on the contrary, which
heats the Examiner’s Room, undergoes no such mollification, and comes
forth at once in an ardent blast of fully 170°; not unlike the simoom of
the desert, as described by travellers. Had a similar nuisance, on the
greater scale, existed in the Long Room, it could not have been endured
by the merchants and other visitors on business: but the disguise of an
evil is a very different thing from its removal. The direct air of the
stove, as it enters the Examiner’s Room, possesses, in an eminent
degree, the disagreeable smell and flavour imparted to air by the action
of red-hot iron; and, in spite of every attention on the part of the
fireman to sweep the stove apparatus from time to time, it carries along
with it abundance of burned dusty particles.

“The leading characteristic of the air in these two rooms, is its
dryness and disagreeable smell. In the Long Room, upon the 11th, the air
indicated, by Daniell’s hygrometer, 70 per cent. of dryness, while the
external atmosphere was nearly saturated with moisture. The thermometer
connected with the dark bulb of that instrument stood at 30° when dew
began to be deposited upon it; while the thermometer in the air stood at
64°. In the court behind the Custom-house, the external air being at
35°, dew was deposited on the dark bulb of the hygrometer by a
depression of only 3°; whereas in the Long Room, on the same day, a
depression of 34° was required to produce that deposition. Air, in such
a dry state, would evaporate 0·44 in. depth of water from a cistern in
the course of twenty-four hours; and its influence on the cutaneous
exhalents must be proportionably great.

“As cast iron always contains, beside the metal itself, more or less
carbon, sulphur, phosphorus, or even arsenic, it is possible that the
smell of air passed over it in an incandescent state, may be owing to
some of these impregnations; for a quantity of noxious effluvia,
inappreciably small, is capable of affecting not only the olfactory
nerves, but the pulmonary organs. I endeavoured to test the air as it
issued from the valve in the Examiner’s Room, by presenting to it pieces
of white paper moistened with a solution of nitrate of silver, and
perceived a slight darkening to take place, as if by sulphurous fumes.
White paper, moistened with sulphuretted hydrogen water, was not in the
least discoloured. The faint impression on the first test paper, may be,
probably, ascribed to sulphurous fumes, proceeding from the ignition of
the myriads of animal and vegetable matters which constantly float in
the atmosphere, as may be seen in the sunbeam admitted into a dark
chamber: to this cause, likewise, the offensive smell of air,
transmitted over red-hot iron, may in some measure be attributed, as
well as to the hydrogen resulting from the decomposition of aqueous
vapour, always present in our atmosphere in abundance; especially close
to the banks of the Thames, below London Bridge.

“When a column of air sweeps furiously across the burning deserts of
Africa and Arabia, constituting the phenomenon called simoom by the
natives, the air becomes not only very hot and dry, but highly
electrical, as is evinced by lightning and thunder. Dry sands, devoid of
vegetation, cannot be conceived to communicate any noxious gas or vapour
to the atmosphere, like the malaria of marshes, called miasmata: it is,
hence, highly probable that the blast of the simoom owes its deadly
malignity, in reference to animal as well as vegetable life, simply to
extreme heat, dryness, and electrical disturbance. Similar conditions,
though on a smaller scale, exist in what is called the bell, or cockle,
apparatus for heating the Long Room and the Examiner’s apartment in the
Custom-house. It consists of a series of inverted, hollow, flattened
pyramids of cast iron, with an oblong base, rather small in their
dimensions, to do their work sufficiently in cold weather, when
moderately heated. The inside of the pyramids is exposed to the flames
of coke furnaces, which heat them frequently to incandescence, while
currents of cold air are directed to their exterior surfaces by numerous
sheet-iron channels. The incandescence of these pyramids, or bells, as
they are vulgarly called, was proved by pieces of paper taking fire when
I laid them on the summits. Again, since air becomes electrical when it
is rapidly blown upon the surfaces of certain bodies, it occurred to me
that the air which escapes into the Examiner’s Room might be in this
predicament. It certainly excites the sensation of a cobweb playing
round the head, which is well known to all who are familiar with
electrical machines. To determine this point, I presented a condensing
gold-leaf electrometer to the said current of hot air, and obtained
faint divergence with negative electricity. The electricity must be
impaired in its tension, however, in consequence of the air escaping
through an iron grating, and striking against the flat iron valves, both
of which tend to restore the electric equilibrium. The air blast,
moreover, by being diffused round the glass of the condenser apparatus,
would somewhat mask the appearances. Were it worth while, an apparatus
might be readily constructed for determining this point, without any
such sources of fallacy. The influence of an atmosphere charged with
electricity in exciting headache and confusion of thought in many
persons, is universally known.

“The fetid burned odour of the stove air, and its excessive avidity for
moisture, are of themselves, however, sufficient causes of the general
indisposition produced among the gentlemen who are permanently exposed
to it in the discharge of their public duties.

“From there being nearly a vacuum, as to aqueous vapour, in the said
air, while there is nearly a plenum in the external atmosphere round
about the Custom-house, the vicissitudes of feeling in those who have
occasion to go out and in frequently, must be highly detrimental to
health. The permanent action of an artificial desiccated air on the
animal economy may be stated as follows:--

“The living body is continually emitting a transpirable matter, the
quantity of which, in a grown up man, will depend partly on the activity
of the cutaneous exhalents, and partly on the relative dryness or
moisture of the circumambient medium. Its average amount, in common
circumstances, has been estimated at 20 ounces in twenty-four hours.

“When plunged in a very dry air, the insensible perspiration will be
increased; and, as it is a true evaporation or gasefaction, it will
generate cold proportionably to its amount. Those parts of the body
which are most insulated in the air, and furthest from the heart, such
as the extremities, will feel this refrigerating influence most
powerfully. Hence the coldness of the hands and feet, so generally felt
by the inmates of the apartment, though its temperature be at or above
60°. The brain, being screened by the skull from this evaporating
influence, will remain relatively hot, and will get surcharged, besides,
with the fluids which are repelled from the extremities by the
condensation, or contraction, of the blood-vessels, caused by cold.
Hence the affections of the head, such as tension, and its dangerous
consequences. If sensible perspiration happen, from debility, to break
forth from a system previously relaxed, and plunged into dry air, so
attractive of vapour, it will be of the kind called a cold clammy sweat
on the sides and back, as experienced by many inmates of the Long Room.

“Such, in my humble apprehension, is a rationale of the phenomena
observed at the Custom-house. Similar effects have resulted from hot-air
stoves of a similar kind in many other situations.

“After the most mature physical and medical investigation, I am of
opinion that the circumstances above specified cannot act permanently
upon human beings, without impairing their constitutions, and reducing
the value of their lives. The Directors of the Customs Fund are
therefore justified in their apprehensions, ‘that the mode of heating
the Long Room is injurious to the health of persons employed therein,
and that it must unduly shorten the duration of life.’

“It may be admitted, as a general principle, that the comfort of
sedentary individuals, occupying large apartments during the winter
months, cannot be adequately secured by the mere influx of hot air from
separate stove-rooms: it requires the genial influence of radiating
surfaces in the apartments themselves, such as of open fires, of pipes,
or other vessels filled with hot water or steam. The clothing of our
bodies, exposed to such radiation in a pure, fresh, somewhat cool and
bracing air, absorbs a much more agreeable warmth than it could acquire
by being merely immersed in an atmosphere heated even to 62° Fahr., like
that of the Long Room. In the former predicament, the lungs are supplied
with a relatively dense air, say at 52° Fahr.; while the external
surface of the body or the clothing is maintained at, perhaps, 70° or
75°. This distinctive circumstance has not, I believe, been hitherto
duly considered by the stove doctors, each intent on puffing his own
pecuniary interest; but it is obviously one of great importance, and
which the English people would do well to keep in view; because it is
owing to our domestic apartments being heated by open fires, and our
factories by steam pipes, that the health of our population, and the
expectation of life among all orders in this country, are so much better
than in France and Germany, where hot-air stoves, neither agreeable nor
inoffensive, and in endless variety of form, are generally employed.

“In conclusion, I take leave to state to you my firm conviction that the
only method of warming your Long Room and subsidiary apartments,
combining salubrity, safety, and economy, with convenience in erection
and durable comfort in use, is by a series of steam pipes laid along the
floor, at the line of the desk partitions, in suitable lengths, with
small arched junction-pipes rising over the several doorways, to keep
the passages clear, and at the same time to allow a free expansion and
contraction in the pipes, thereby providing for the permanent soundness
of the joints.”

It would not be difficult to construct a stove or stove-grate which
should combine economy and comfort of warming an apartment, with
briskness of combustion and durability of the fire, without any noxious
deflux of carbonic acid. See CHIMNEY.


STRASS; see PASTES.


STRAW-HAT MANUFACTURE. The mode of preparing the Tuscany or Italian
straw, is by pulling the bearded wheat while the ear is in a soft milky
state, the corn having been sown very close, and of consequence produced
in a thin, short, and dwindled condition. The straw, with its ears and
roots, is spread out thinly upon the ground in fine hot weather, for
three or four days or more, in order to dry the sap; it is then tied up
in bundles and stacked, for the purpose of enabling the heat of the mow
to drive off any remaining moisture. It is important to keep the ends of
the straw air-tight, in order to retain the pith, and prevent its gummy
particles from passing off by evaporation.

After the straw has been about a month in the mow, it is removed to a
meadow and spread out, that the dew may act upon it, together with the
sun and air, and promote the bleaching, it being necessary frequently to
turn the straw while this process is going on. The first process of
bleaching being complete, the lower joint and root is pulled from the
straw, leaving the upper part fit for use, which is then sorted
according to qualities; and after being submitted to the action of
steam, for the purpose of extracting its colour, and then to a
fumigation of sulphur, to complete the bleaching, the straws are in a
condition to be platted or woven into hats and bonnets, and are in that
state imported into England in bundles, the dried ears of the wheat
being still on the straw.

Straw may be easily bleached by a solution of chloride of lime, and also
by sulphuring. For the latter purpose, a cask open at both ends, with
its seams papered, is to be set upright a few inches from the ground,
having a hoop nailed to its inside, about six inches beneath the top, to
support another hoop with a net stretched across it, upon which the
straw is to be laid in successive handfuls loosely crossing each other.
The cask having been covered with a tight overlapping lid, stuffed with
lists of cloth, a brazier of burning charcoal is to be inserted within
the bottom, and an iron dish containing pieces of brimstone is to be put
upon the brazier. The brimstone soon takes fire, and fills the cask with
sulphurous acid gas, whereby the straw gets bleached in the course of
three or four hours. Care should be taken to prevent such a violent
combustion of the sulphur as might cause black burned spots, for these
cannot be afterwards removed. The straw, after being aired and softened
by spreading it upon the grass for a night, is ready to be split,
preparatory to dyeing. Blue is given by a boiling-hot solution of indigo
in sulphuric acid, called _Saxon blue_, diluted to the desired shade;
yellow, by decoction of turmeric; red, by boiling hanks of coarse
scarlet wool in a bath of weak alum water, containing the straw; or
directly, by cochineal, salt of tin, and tartar. Brazil wood and archil
are also employed for dyeing straw. For the other colours, see their
respective titles in this Dictionary.


STRETCHING MACHINE. Cotton goods and other textile fabrics, either white
or printed, are prepared for the market by being stretched in a proper
machine, which lays all their warp and woof yarns in truly parallel
positions. A very ingenious and effective mechanism of this kind was
made the subject of a patent by Mr. Samuel Morand, of Manchester, in
April, 1834, which serves to extend the width of calico pieces, or of
other cloths woven of cotton, wool, silk, or flax, after they have
become shrunk in the processes of bleaching, dyeing, &c. I regret that
the limits of this volume will not admit of its description. The
specification of the patent is published in Newton’s Journal, for
December, 1835.


STRONTIA, one of the alkaline earths, of which _strontium_ is the
metallic basis, occurs in a crystalline state, as a carbonate, in the
lead mines of Strontian in Argyleshire, whence its name. The sulphate is
found crystallized near Bristol, and in several other parts of the
world; but strontitic minerals are rather rare. The pure earth is
prepared exactly like baryta, from either the carbonate or the sulphate.
It is a grayish-white powder, infusible in the furnace, of a specific
gravity approaching that of baryta, having an acrid, burning taste, but
not so corrosive as baryta, though sharper than lime. It becomes hot
when moistened, and slakes into a pulverulent hydrate, dissolves in 150
parts of water at 60°, and in much less at the boiling point, forming an
alkaline solution called _strontia_ water, which deposits crystals in
four-sided tables as it cools. These contain 68 per cent. of water, are
soluble in 52 parts of water at 60°, and in about 2 parts of boiling
water; when heated they part with 53 parts of water, but retain the
other 15 parts, even at a red heat. The dry earth consists of 84·55 of
base, and 15·45 of oxygen. It is readily distinguished from baryta, by
its inferior solubility, and by its soluble salts giving a red tinge to
flame, while those of baryta give a yellow tinge. Fluosilicic acid and
iodate of soda precipitate the salts of the latter earth, but not those
of the former. The compounds of strontia are not poisonous, like those
of baryta. The only preparation of strontia used in the arts is the
NITRATE, which see.


STRYCHNIA, is an alkaline base, extracted from the _Strychnos nux
vomica_, _Strychnos ignatia_, and the _Upas tiente_; which has been
employed in medicine by some of the poison doctors, but is of no use in
any of the arts. When introduced into the stomach, strychnia acts with
fearful energy, causing lock-jaw immediately, and the death of the
animal in a very short time. Half a grain, blown into the throat of a
rabbit, proves fatal in five minutes.


STUCCO. See GYPSUM.


SUBERIC ACID, is prepared by digesting grated cork with nitric acid. It
forms crystals, which sublime in white vapours when heated.


SUBLIMATE, is any solid matter resulting from condensed vapours, and,


SUBLIMATION, is the process by which the volatile particles are raised
by heat, and condensed into a crystalline mass. See CALOMEL and
SAL-AMMONIAC, for examples.


SUBSALT, is a salt in which the base is not saturated with acid; as
subacetate of lead.


SUCCINIC ACID, _Acid of amber_, (_Acide succinique_, Fr.;
_Bernsteinsaüre_, Germ.) is obtained by distilling coarsely pounded
amber in a retort by itself, with a heat gradually raised; or mixed with
one-twelfth of its weight of sulphuric acid, diluted with half its
weight of water. The acid which sublimes is to be dissolved in hot
water, to be saturated with potassa or soda, boiled with bone black, to
remove the foul empyreumatic oily matter, filtered, and precipitated by
nitrate of lead, to convert it into an insoluble succinate; which being
washed, is to be decomposed by the equivalent quantity of sulphuric
acid. Pure succinic acid forms transparent prisms. The succinate of
ammonia is an excellent reagent for detecting and separating iron.


SUGAR (_Sucre_, Fr.; _Zucker_, Germ.); is the sweet constituent of
vegetable and animal products. It may be distinguished into two
principal species. The first, which occurs in the sugar-cane, the
beet-root, and the maple, crystallizes in oblique four-sided prisms,
terminated by two-sided summits; it has a sweetening power which may be
represented by 100; and in circumpolarization it bends the luminous rays
to the right. The second occurs ready formed in ripe grapes and other
fruits; it is also produced by treating starch with diastase or
sulphuric acid. This species forms cauliflower concretions, but not true
crystals; it has a sweetening power which may be represented by 60, and
in circumpolarization it bends the rays to the left. Besides these two
principal kinds of sugar, some others are distinguished by chemists; as
the sugar of milk, of manna, of certain mushrooms, of liquorice-root,
and that obtained from sawdust and glue by the action of sulphuric acid;
but they have no importance in a manufacturing point of view.

Sugar, extracted either from the cane, the beet, or the maple, is
identical in its properties and composition, when refined to the same
pitch of purity; only that of the beet seems to surpass the other two in
cohesive force, since larger and firmer crystals of it are obtained from
a clarified solution of equal density. It contains 5·3 per cent. of
combined water, which can be separated only by uniting it with oxide of
lead, into what has been called a saccharate; made by mixing syrup with
finely ground litharge, and evaporating the mixture to dryness upon a
steam-bath. When sugar is exposed to a heat of 400° F., it melts into a
brown pasty mass, but still retains its water of composition. Sugar thus
fused is no longer capable of crystallization, and is called caramel by
the French. It is used for colouring liqueurs. Indeed sugar is so
susceptible of change by heat, that if a colourless solution of it be
exposed for some time to the temperature of boiling water, it becomes
brown and partially uncrystallizable. Acids exercise such an injurious
influence upon sugar, that after remaining in contact with it for a
little while, though they be rendered thoroughly neutral, a great part
of the sugar will refuse to crystallize. Thus, if 3 parts of oxalic or
tartaric acid be added to sugar in solution, no crystals of sugar can be
obtained by evaporation, even though the acids be neutralized by chalk
or carbonate of lime. By boiling cane sugar with dilute sulphuric acid,
it is changed into starch sugar. Manufacturers of sugar should be,
therefore, particularly watchful against every acidulous taint or
impregnation. Nitric acid converts sugar into oxalic and malic acids.
Alkaline matter is likewise most detrimental to the grain of sugar; as
is always evinced by the large quantity of molasses formed, when an
excess of temper lime has been used in clarifying the juice of the cane
or the beet. When one piece of lump sugar is rubbed against another in
the dark, a phosphorescent light is emitted.

Sugar is soluble in all proportions in water; but it takes four parts of
spirits of wine, of spec. grav. 0·830, and 80 of absolute alcohol, to
dissolve it, both being at a boiling temperature. As the alcohol cools,
it deposits the sugar in small crystals. Caramelized and
uncrystallizable sugar dissolves readily in alcohol. Pure sugar is
unchangeable in the air, even when dissolved in a good deal of water, if
the solution be kept covered and in the dark; but with a very small
addition of gluten, the solution soon begins to ferment, whereby the
sugar is decomposed into alcohol and carbonic acid, and ultimately into
acetic acid.

Sugar forms chemical compounds with the salifiable bases. It dissolves
readily in caustic potash lye, whereby it loses its sweet taste, and
affords on evaporation a mass which is insoluble in alcohol. When the
lye is neutralized by sulphuric acid, the sugar recovers its sweet
taste, and may be separated from the sulphate of potash by alcohol, but
it will no longer crystallize.

That syrup possesses the property of dissolving the alkaline earths,
lime, magnesia, strontites, barytes, was demonstrated long ago by Mr.
Ramsay of Glasgow, by experiments published in Nicholson’s Journal, vol.
xviii. page 9, for September 1807. He found that syrup is capable of
dissolving half as much lime as it contains of sugar; and as much
strontites as sugar. Magnesia dissolved in much smaller quantity, and
barytes seemed to decompose the sugar entirely. These results have been
since confirmed by Professor Daniell. Mr. Ramsay characterized sugar
treated with lime as weak, from its sweetening power being impaired;
from its solution he obtained, after some time, a deposit of calcareous
carbonate. M. Pelouze has lately shown that the carbonic acid in this
case is derived from the atmosphere, and is not formed at the expense of
the elements of the sugar, as Mr. Daniell had asserted.

Sugar forms with oxide of lead two combinations; the one soluble, the
other insoluble. Oxide of lead digested in syrup dissolves to a certain
amount, forms a yellowish liquor, which possesses an alkaline reaction,
and leaves after evaporation an uncrystallizable, viscid, deliquescent
mass. If syrup be boiled with oxide of lead in excess, if the solution
be filtered boiling hot, and if the phial be corked in which it is
received, white bulky flocks will fall to its bottom in the course of 24
hours. This compound is best dried _in vacuo_. It is in both cases
light, tasteless, and insoluble in cold and boiling water; it takes fire
like German tinder (AMADOU), when touched at one point with an ignited
body, and burns away, leaving small globules of lead. It dissolves in
acids, and also in neutral acetate of lead, which forms with the oxide a
subsalt, and sets the sugar free. Carbonic acid gas passed through
water, in which the above saccharate is diffused, decomposes it with
precipitation of carbonate of lead. It consists of 58·26 parts of oxide
of lead, and 41·74 sugar, in 100 parts. From the powerful action
exercised upon sugar by acids and oxide of lead, we may see the fallacy
and danger of using these chemical reagents in sugar-refining. Sugar
possesses the remarkable property of dissolving the oxide, as well as
the subacetate of copper (verdigris), and of counteracting their
poisonous operation. Orfila found that a dose of verdigris, which would
kill a dog in an hour or two, might be swallowed with impunity, provided
it was mixed with a considerable quantity of sugar. When a solution of
sugar is boiled with the acetate of copper, it causes an abundant
precipitate of protoxide of copper; when boiled with the nitrates of
mercury and silver, or the chloride of gold, it reduces the respective
bases to the metallic state.

The following TABLE shows the quantities of Sugar contained in Syrups of
the annexed specific gravities.[63] It was the result of experiments
carefully made.

  [63] The author, in minutes of evidence of Molasses Committee of the
  House of Commons, 1831, p. 142.

  +------------------------+-------------+
  |Experimental spec. grav.|Sugar in 100.|
  | of solution at 60° F.  | by weight.  |
  +------------------------+-------------+
  |         1·3260         |    66·666   |
  |         1·2310         |    50·000   |
  |         1·1777         |    40·000   |
  |         1·440          |    33·333   |
  |         1·1340         |    31·250   |
  |         1·1250         |    29·412   |
  |         1·1110         |    26·316   |
  |         1·1045         |    25·000   |
  |         1·0905         |    21·740   |
  |         1·0820         |    20·000   |
  |         1·0685         |    16·666   |
  |         1·0500         |    12·500   |
  |         1·0395         |    10·000   |
  +------------------------+-------------+

If the decimal part of the number denoting the specific gravity of
syrup, be multiplied by 26, the product will denote very nearly the
quantity of sugar per gallon in pounds weight, at the given specific
gravity.[64]

  [64] This rule was annexed to an extensive table, representing the
  quantities of sugar per gallon corresponding to the specific gravities
  of the syrup, constructed by the author for the Excise, in
  subserviency to the Beet-root Bill.

Sugar has been analyzed by several chemists; the following TABLE
exhibits some of their results:--

  +--------+------------+----------+------+-----+-------+
  |        | Gay Lussac |          |      |     |       |
  |        |and Thenard.|Berzelius.|Prout.|Ure. |       |
  +--------+------------+----------+------+-----+-------+
  |Oxygen  |    56·63   |  49·856  |53·35 |50·33|in 100.|
  |Carbon  |    42·47   |  43·265  |39·99 |43·38|  --   |
  |Hydrogen|     6·90   |   6·875  | 6·66 | 6·29|  --   |
  +--------+------------+----------+------+-----+-------+

_Of the sugar cane, and the extraction of sugar from it._--Humboldt,
after the most elaborate historical and botanical researches in the New
World, has arrived at the conclusion, that before America was discovered
by the Spaniards, the inhabitants of that continent and the adjacent
islands were entirely unacquainted with the sugar canes, with any of our
corn plants, and with rice. The progressive diffusion of the cane has
been thus traced out by the partisans of its oriental origin. From the
interior of Asia it was transplanted first into Cyprus, and thence into
Sicily, or possibly by the Saracens directly into the latter island, in
which a large quantity of sugar was manufactured in the year 1148.
Lafitau relates the donation made by William the Second, king of Sicily,
to the convent of St. Benoit, of a mill for crushing sugar canes, along
with all its privileges, workmen, and dependencies: which remarkable
gift bears the date of 1166. According to this author, the sugar cane
must have been imported into Europe at the period of the Crusades. The
monk Albertus Aquensis, in the description which he has given of the
processes employed at Acre and at Tripoli to extract sugar, says, that
in the Holy Land, the Christian soldiers being short of provisions, had
recourse to sugar canes, which they chewed for subsistence. Towards the
year 1420, Dom Henry, regent of Portugal, caused the sugar cane to be
imported into Madeira from Sicily. This plant succeeded perfectly in
Madeira and the Canaries; and until the discovery of America these
islands supplied Europe with the greater portion of the sugar which it
consumed.

The cane is said by some to have passed from the Canaries into the
Brazils; but by others, from the coast of Angola in Africa, where the
Portuguese had a sugar colony. It was transported in 1506, from the
Brazils and the Canaries, into Hispaniola or Hayti, where several
crushing-mills were constructed in a short time. It would appear,
moreover, from the statement of Peter Martyr, in the third book of his
first Decade, written during the second expedition of Christopher
Columbus, which happened between 1493 and 1495, that even at this date
the cultivation of the sugar cane was widely spread in St. Domingo. It
may therefore be supposed to have been introduced here by Columbus
himself, at his first voyage, along with other productions of Spain and
the Canaries, and that its cultivation had come into considerable
activity at the period of his second expedition. Towards the middle of
the 17th century, the sugar cane was imported into Barbadoes from
Brazil, then into the other English West Indian possessions, into the
Spanish Islands on the coast of America, into Mexico, Peru, Chile, and,
last of all, into the French, Dutch, and Danish colonies.

The sugar cane, _Arundo saccharifera_, is a plant of the graminiferous
family, which varies in height from 8 to 10, or even to 20 feet. Its
diameter is about an inch and a half; its stem is dense, brittle, and of
a green hue, which verges to yellow at the approach of maturity. It is
divided by prominent annular joints of a whitish-yellow colour, the
plane of which is perpendicular to the axis of the stem. These joints
are placed about 3 inches apart; and send forth leaves, which fall off
with the ripening of the plant. The leaves are 3 or 4 feet long, flat,
straight, pointed, from 1 to 2 inches in breadth, of a sea-green tint,
striated in their length, alternate, embracing the stem by their base.
They are marked along their edges with almost imperceptible teeth. In
the 11th or 12th month of their growth, the canes push forth at their
top a sprout 7 or 8 feet in height, nearly half an inch in diameter,
smooth, and without joints, to which the name _arrow_ is given. This is
terminated by an ample panicle, about 2 feet long, divided into several
knotty ramifications, composed of very numerous flowers, of a white
colour, apetalous, and furnished with 3 stamens, the anthers of which
are a little oblong. The roots of the sugar cane are jointed and nearly
cylindrical; in diameter they are about one twelfth of an inch; in their
utmost length 1 foot, presenting over their surface a few short
radicles.

The stem of the cane in its ripe state is heavy, very smooth, brittle,
of a yellowish-violet, or whitish colour, according to the variety. It
is filled with a fibrous, spongy, dirty-white pith, which contains very
abundant sweet juice. This juice is elaborated separately in each
internodary portion, the functions of which are in this respect
independent of the portions above and below. The cane may be propagated
by seeds or buds with equal facility; but it is usually done by cuttings
or joints of proper lengths, from 15 to 20 inches, in proportion to the
nearness of the joints, which are generally taken from the tops of the
canes, just below the leaves.

There are several varieties of the sugar-cane plant. The first, and
longest known, is the creole, or common sugar cane, which was originally
introduced at Madeira. It grows freely in every region within the
tropics, on a moist soil, even at an elevation of 3000 feet above the
level of the sea. In Mexico, among the mountains of Caudina-Masca, it is
cultivated to a height of more than 5000 feet. The quantity and quality
of sugar which it yields, is proportional to the heat of the place where
it grows, provided it be not too moist and marshy.

The second variety of this plant is the Otaheitan cane. It was
introduced into the West Indies about the end of the 18th century. This
variety, stronger, taller, with longer spaces between the joints,
quicker in its growth, and much more productive in sugar, succeeds
perfectly well in lands which seem too much impoverished to grow the
ordinary cane. It sends forth shoots at temperatures which chill the
growth and development of the creole plant. Its maturation does not take
more than a year, and is accomplished sometimes in nine months. From the
strength of its stem, and the woodiness of its fibres, it better resists
the storms. It displays a better inflorescence, weighs a third more,
affords a sixth more juice, and a fourth more sugar, than the common
variety. Its main advantage, however, is to yield four crops in the same
time that the creole cane yields only three. Its juice contains less
feculency and mucilage, whence its sugar is more easily crystallized,
and of a fairer colour.

Besides these two varieties, another kind is described by Humboldt and
Bonpland, under the name of the _violet_ sugar-cane, for its haum and
leaves are of this colour. It was transported from Batavia in 1782. It
flowers a month sooner than the rest, that is, in August, but it yields
less solid sugar, and more liquid, both of which have a violet tint.

In saying that the cane may be propagated by seeds as well as buds, we
must remark, that in all the colonies of the New World, the plant
flowers, indeed, but it then sends forth a shoot (_arrow_), that is, its
stem elongates, and the seed-vessel proves abortive. For this reason,
the bud-joints must there be used for its propagation. It grows to seed,
however, in India. This circumstance occurs with some other plants,
which, when propagated by their roots, cease to yield fertile seeds;
such as the banana, the bread-fruit, the lily, and the tulip.

In the proper season for planting, the ground is marked out by a line
into rows three or four feet asunder, in which rows the canes are
planted about two feet apart. The series of rows is divided into pieces
of land 60 or 70 feet broad, leaving spaces of about 20 feet, for the
convenience of passage, and for the admission of sun and air between the
stems. Canes are usually planted in trenches, about 6 or 8 inches deep,
made with the hand-hoe, the raised soil being heaped to one side, for
covering-in the young cane; into the holes a negro drops the number of
cuttings intended to be inserted, the digging being performed by other
negroes. The earth is then drawn about the hillocks with the hoe. This
labour has been, however, in many places better and more cheaply
performed by the plough; a deep furrow being made, into which the
cuttings are regularly planted, and the mould then properly turned in.
If the ground is to be afterwards kept clear by the horse-hoe, the rows
of canes should be 5 feet asunder, and the hillocks 2-1/2 feet distant,
with only one cane left in one hillock. After some shoots appear, the
sooner the horse-hoe is used, the more will the plants thrive, by
keeping the weeds under, and stirring up the soil. Plant-canes of the
first growth have been known to yield, on the brick-mould of Jamaica, in
very fine seasons, 2-1/2 tons of sugar per acre. The proper season for
planting the cane-slips, containing the buds, namely, the top part of
the cane, stripped of its leaves, and the two or three upper joints, is
in the interval between August and the beginning of November. Favoured
by the autumnal weather, the young plants become luxuriant enough to
shade the ground before the dry season sets in; thereby keeping the
roots cool and moderately moist. By this arrangement the creole canes
are ripe for the mill in the beginning of the second year, so as to
enable the manager to finish his crop early in June. There is no greater
error in the colonist than planting canes at an improper season of the
year, whereby his whole system of operations becomes disturbed and, in a
certain degree, abortive.

The withering and fall of a leaf afford a good criterion of the maturity
of the cane-joint to which it belonged; so that the eight last leafless
joints of two canes, which are cut the same day, have exactly the same
age and the same ripeness, though one of the canes be 15 and the other
only 10 months old. Those, however, cut towards the end of the dry
season, before the rains begin to fall, produce better sugar than those
cut in the rainy season, as they are then somewhat diluted with watery
juice, and require more evaporation to form sugar. It may be reckoned a
fair average product, when one pound of sugar is obtained from one
gallon (English) of juice.

_Rattoons_ (a word corrupted from _rejettons_) are the sprouts or
suckers that spring from the roots or stoles of the canes that have been
previously cut for sugar. They are commonly ripe in 12 months; but canes
of the first growth are called plant-canes, being the direct produce of
the original cuttings or germs placed in the ground, and require a
longer period to bring them to maturity. The first yearly return from
the roots that are cut over, are called first rattoons; the second
year’s growth, second rattoons; and so on, according to their age.
Instead of stocking up his rattoons, holing, and planting the land anew,
the planter suffers the stoles to continue in the ground, and contents
himself, as the cane-fields become thin and impoverished, with supplying
the vacant places with fresh plants. By these means, and with the aid of
manure, the produce of sugar per acre, if not apparently equal to that
from plant-canes, gives perhaps in the long run as great returns to the
owner, considering the relative proportion of the labour and expense
attending the different systems. The common yielding on proper land,
such as the red soil of Trelawney, in Jamaica, is 7 hogsheads, of 16
cwt. each, to 10 acres of rattoons cut annually; and such a plantation
lasts from 6 to 10 years.

When the planted canes are ripe, they are cut close above the ground, by
an oblique section, into lengths of 3 or 4 feet, and transported in
bundles to the mill-house. If the roots be then cut off, a few inches
below the surface of the soil, and covered up with fine mould, they will
push forth more prolific offsets or rattoons, than when left projecting
in the common way.

OF SUGAR MILLS.

The first machines employed to squeeze the canes, were mills similar to
those which serve to crush apples in some cider districts, or somewhat
like tan-mills. In the centre of a circular area, of about 7 or 8 feet
in diameter, a vertical heavy wheel was made to revolve on its edge, by
attaching a horse to a cross beam projecting horizontally from it, and
making it move in a circular path. The cane pieces were strewed on the
somewhat concave bed in the path of the wheel, and the juice expressed
flowed away through a channel or gutter in the lowest part. This machine
was tedious and unproductive. It was replaced by the vertical
cylinder-mill of Gonzales de Velosa; which has continued till modern
times, with little variation of external form, but is now generally
superseded by the sugar-mill with horizontal cylinders.

SUGAR-CANE MILL.

_Specification of, and Observations on, the Construction and Use of the
best Horizontal Sugar-mill._

_Fig._ 1075. Front elevation of the entire mill. _Fig._ 1076. Horizontal
plan. _Fig._ 1077. End elevation. _Fig._ 1078. Diagram, showing the
dispositions of the feeding and delivering rollers, feeding board,
returner, and delivering board.

[Illustration: 1075 1076]

_Fig._ 1075. A, A, solid foundation of masonry; B, B, bed plate; C, C,
headstocks or standards; D, main shaft (seen only in _fig._ 1076.); E,
intermediate shaft; F, F, plummer-blocks of main shaft D, (seen only in
_fig._ 1076.); H, driving pinion on the fly-wheel shaft of engine; I,
first motion mortise wheel driven by the pinion; K, second motion
pinion, on the same shaft; L, second motion mortise-wheel, on the main
shaft; M, brays of wood, holding the plummer-blocks for shaft D; N,
wrought-iron straps connecting the brays to the standards C, C; O, O,
regulating screws for the brays; P, top roller and gudgeons; Q and R,
the lower or feeding and delivering rollers; S, clutch for the connexion
of the side of lower rollers Q and R, to the main shaft (seen only in
_fig._ 1076.); T, T, the drain gutters of the mill-bed (seen only in
_fig._ 1076.).

The same letters of reference are placed respectively on the same parts
of the mill in each of _figs._ 1075, 1076, and 1077.

[Illustration: 1077 1078]

The relative disposition of the rollers is shown in the diagram, _fig._
1078., in which A is the top roller; B, the feeding roller; C, the
delivering roller; D, the returner; E, the feed board; F, the delivering
board.

The rollers are made two inches and a quarter to two inches and a half
thick, and ribbed in the centre. The feeding and delivering rollers have
small flanges at their ends (as shown in _fig._ 1075.), between which
the top roller is placed; these flanges prevent the pressed canes or
begass from working into the mill-bed. The feeding and top rollers are
generally fluted, and sometimes diagonally, enabling them the better to
seize the canes from the feed-board. It is, however, on the whole,
considered better to flute the feeding roller only, leaving the top and
delivering rollers plane; when the top roller is fluted, it should be
very slightly, for, after the work of a few weeks, its surface becomes
sufficiently rough to bite the canes effectively. The practical
disadvantage of fluting the delivering rollers, is in the grooves
carrying round a portion of liquor, which is speedily absorbed by the
spongy begass, as well as in breaking the begass itself, and thus
causing great waste.

The feed board is now generally made of cast iron, and is placed at a
considerable inclination, to allow the canes to slip the more easily
down to the rollers. The returner is also of cast iron, serrated on the
edge, to admit the free flowing of the liquor to the mill-bed. The
concave returner, formerly used, was pierced with holes to drain off the
liquor, but it had the serious disadvantage of the holes choking up with
the splinters of the cane, and has therefore been discarded. The
delivering board is of cast iron, fitted close to the roller, to detach
any begass that may adhere to it, and otherwise mix with the liquor.

In Demerara, Surinam, Cayenne, and the alluvial district of Trinidad, it
is usual to attach to the mill a liquor-pump, with two barrels and three
adjustments of stroke. This is worked from the gudgeon of the top
roller. In action, the liquor from the gutter of the mill-bed runs into
the cistern of the pump, and is raised by the pump to the gutter which
leads to the clarifier or coppers. Such pumps have brass barrels and
copper discharging pipes, are worked with a very slow motion, and
require to be carefully adjusted to the quantity of liquor to be raised,
which, without such precaution, is either not drawn off sufficiently
quick, or is agitated with air in the barrels, and delivered to the
gutter in a state of fermentation.

In working this mill, the feeding roller is kept about half an inch
distant from the upper roller, but the delivering roller is placed so
close to it, as to allow the begass to pass through unbroken.

The practice with this mill is to cut the sugar canes into short lengths
of about three feet, and bring them to the mill tied up in small
bundles; there the feeder unties them, throws them on the feed board,
and spreads them so that they may cross each other as little as
possible. They are taken in by the feed rollers, which split and
slightly press them; the liquor flows down, and, the returner guiding
the canes between the top and delivering rollers, they receive the final
pressure, and are turned out on the mill-floor, while the liquor runs
back and falls into the mill-bed. The begass, then in the state of
_pith_, adhering to the skin of the cane, is tied up in bundles, and
after being exposed a short time to the sun, is finally stored in the
begass-house for fuel. By an important improvement in this stage of the
process, recently introduced, the begass is carried to the begass-house
by a carrier chain, worked by the engine.

The relative merits of horizontal and vertical sugar-mills on this
construction, may be thus stated:--The horizontal mill is cheaper in
construction, and is more easily fixed; the process of feeding is
performed at about one-half of the labour, and in a much superior
manner; the returner guides the canes to receive the last pressure more
perfectly; and the begass is not so much broken as in the vertical mill;
but left tolerably entire, so as to be tied, dried, and stored, with
less trouble and waste.

The vertical mill has a considerable advantage, in being more easily
washed; and it can be readily and cheaply mounted in wooden framing; but
the great labour of feeding the vertical mill, renders it nearly
inapplicable to any higher power than that of about ten horses. In
situations where the moving power is a windmill, or a cattle gin, the
vertical mill may be preferred.

The scale of produce of such mills varies according to the climate and
soil. In Demerara, a well constructed engine and mill will produce about
100 gallons of liquor per hour for each horse power.

The dimensions of the most approved horizontal mills are these:--

  +----------------------+------------------+--------------------+
  |Horse-power of Engine.|Length of Rollers.|Diameter of Rollers.|
  +----------------------+------------------+--------------------+
  |                      |   _ft._  _in._   |     _inches._      |
  |           8          |     4      0     |        25          |
  |          10          |     4      6     |        27          |
  |          12          |     4      8     |        28          |
  +----------------------+------------------+--------------------+

The surface speed of the rollers is 3·4 or 3·6 feet per minute; and to
provide for the varying resistance arising from irregular feeding, or
the accidental crossing of the canes, by which the engine is often
_brought up_ so suddenly as to break the fly-wheel shaft, it is
necessary to make both the shaft and the fly-wheel of unusual strength
and weight.

Sugar is manufactured in the East Indies by two distinct classes of
persons; the _ryots_, who raise the sugar cane, extract its juice, and
inspissate it to a syrupy consistence; and the _goldars_, who complete
the conversion into sugar.

The _ryots_ are the farmers, or actual cultivators of the soil; but,
properly speaking, they are merely peasants, toiling under oppressive
landlords, and miserably poor. After they cut the canes, they extract
the juice by one or other of the rude mills or mortars presently to be
described, and boil it down to an entire mass, which is generically
called _goor_, without making any attempt to clarify it, or separate the
granular sugar from the uncrystallizable molasses. This goor is of
various qualities; one of which, in most common use for making sugar, is
known amongst the English settlers under the name of _jaggery_. There is
a caste in Ceylon, called _jaggeraros_, who make sugar from the produce
of the _Caryota urens_, or Kitul tree; and the sugar is styled
_jaggery_. Sugar is not usually made in Ceylon from the sugar cane; but
either from the juice of the Kitul, from the _Cocos nucifera_, or the
_Borassus flabelliformis_ (the Palmyra tree).

Several sorts of cane are cultivated in India.

[Illustration: 1079]

The _Cadjoolee_ (_fig._ 1079.) is a purple-coloured cane; yields a
sweeter and richer juice than the yellow or light coloured, but in less
quantities, and is harder to press. It grows in dry lands. When eaten
raw, it is somewhat dry and pithy in the mouth, but is esteemed very
good for making sugar. It is not known to the West India planter. The
leaves rise from a point 6 feet above the ground. An oblique and
transverse section of the cane is represented by the parts near the
bottom of the figure.

The _Pooree_ is a light-coloured cane, yellow, inclining to white,
deeper yellow when ripe and on rich ground. West India planters consider
it the same sort as one of theirs. It is softer and more juicy than the
preceding, but the juice is less rich, and produces a weaker sugar. It
requires seven parts of pooree juice to make as much goor as is produced
from six of the cadjoolee. Much of this cane is brought to the Calcutta
market, and eaten raw.

The _Cullorah_ thrives in swampy lands, is light-coloured, and grows to
a great height. Its juice is more watery, and yields a weaker sugar also
than the cadjoolee. However, since much of Bengal consists of low
grounds, and since the upland canes are apt to suffer from drought, it
deserves encouragement in certain localities.

It is only large farms that cut an acre of cane in a year; one mill,
therefore, and one set of the implements used in inspissating the juice,
although very rude and simple, serve for several farms, and generally
belong to some wealthy man, who lets them out for hire to his poorer
neighbours, the whole of whom unite to clear each other’s fields by
turns; so that though many people and cattle are employed at one of
these miserable sets of works, very few indeed are hired, and the
greater part of the labour is performed by the common stock of the
farms.

The inspissated juice, or extract of cane, called by the natives _goor_,
is of two kinds; one of which may be termed cake extract, and the other
pot extract; both being often denominated _jaggery_, as above stated, by
the English residents.

One-third of an acre of good land in the southern districts, is reckoned
by the farmers to produce 18,891 pounds of cane, and 1,159 pounds of pot
extract. Its produce in cake extract is about 952 pounds.

[Illustration: 1080]

I shall now describe the primitive rude mill and boiler used in
preparing the extract of sugar cane, and which are usually let to the
ryots by the day. The mill in Dinajpur, _fig._ 1080. is on the principle
of a pestle and mortar. The pestle, however, does not beat the canes,
but is rubbed against them, as is done in many chemical triturations;
and the moving force is two oxen. The mortar is generally a tamarind
tree, one end of which is sunk deep in the ground, to give it firmness.
The part projecting _a_, _a_, _a_, _a_, may be about two feet high, and
a foot and a half in diameter; and in the upper end a hollow is cut,
like the small segment of a sphere. In the centre of this, a channel
descends a little way perpendicularly, and then obliquely to one side of
the mortar, so that the juice, as squeezed from the cane, runs off, by
means of a spout _b_, into a strainer _c_, through which it falls into
an earthen pot, that stands in a hole _d_, under the spout. The pestle
_e_, is a tree about 18 feet in length, and 1 foot in diameter, rounded
at its bottom, which rubs against the mortar, and which is secured in
its place by a button or knob, that goes into the channel of the mortar.
The moving force is applied to a horizontal beam _f_, about 16 feet in
length, which turns round about the mortar, and is fastened to it by a
bent bamboo _b_. It is suspended from the upper end of the pestle by a
bamboo _g_, which has been cut with part of the root, in which is formed
a pivot that hangs on the upper point of the pestle. The cattle are
yoked to the horizontal beam, at about ten feet from the mortar, move
round it in a circle, and are driven by a man, who sits on the beam, to
increase the weight of the triturating power. Scarcely any machine more
miserable can be conceived; and it would be totally ineffectual, were
not the cane cut into thin slices. This is a troublesome part of the
operation. The grinder sits on the ground, having before him a bamboo
stake, which is driven into the earth, with a deep notch formed in its
upper end. He passes the canes gradually through this notch, and at the
same time cuts off the slices with a kind of rude chopper.

[Illustration: 1081]

The _boiling apparatus_ is somewhat better contrived, and is placed
under a shed, though the mill is without shelter. The fireplace is a
considerable cavity dug in the ground, and covered with an iron boiler
_p_, _fig._ 1081. At one side of this, is an opening _q_, for throwing
in fuel; and opposite to this, is another opening, which communicates
with the horizontal flue. This is formed by two parallel mud walls _r_,
_r_, _s_, _s_, about 20 feet long, 2 feet high, and 18 inches distant
from each other. A row of eleven earthen boilers _t_, is placed on these
walls, and the interstices _u_, are filled with clay, which completes
the furnace-flue, an opening _v_, being left at the end, for giving vent
to the smoke.

The juice, as it comes from the mill, is first put into the earthen
boiler that is most distant from the fire, and is gradually removed from
one boiler to another, until it reaches the iron one, where the process
is completed. The fireplace is manifestly on the same model as the
boiler range in the West Indies, and may possibly have suggested it,
since the Hindostan furnace is, no doubt, of immemorial usage. The
execution of its parts is very rude and imperfect. The inspissated juice
that can be prepared in 24 hours by such a mill, with 16 men and 20
oxen, amounts to no more than 476 lbs.; and it is only in the southern
parts of the district, where the people work night and day, that the
sugar-works are so productive. In the northern districts, the people
work only during the day, and inspissate about one-half the quantity of
juice. The average daily make of a West India sugar-house, is from 2 to
3 hogsheads, of 16 cwts each.

The Indian manufacturers of sugar purchase the above inspissated juice
or goor from the farmers, and generally prefer that of a granular honey
consistence, which is offered for sale in pots. As this, however, cannot
conveniently be brought from a distance, some of the cake kind is also
employed. The boilers are of two sizes; one adapted for making at each
operation about ten cwt.; the other, about eight and a half. The latter
is the segment of a sphere, nine feet diameter at the mouth; the former
is larger. The boiler is sunk into a cylindrical cavity in the ground,
which serves as a fireplace, so that its edge is just above the floor of
the boiling-house. The fuel is thrown in by an aperture close to one
side of the boiler, and the smoke escapes by a horizontal chimney that
passes out on the opposite side of the hut, and has a small round
aperture, about ten feet distant from the wall, in order to lessen the
danger from fire. Some manufacturers have only one boiler; others as
many as four; but each boiler has a separate hut, in one end of which is
some spare fuel; and in the other, some bamboo stages, which support
cloth strainers, that are used in the operation. This hut is about
twenty-four cubits long, and ten broad; has mud walls, six cubits high;
and is raised about one cubit above the ground.

For each boiler, two other houses are required: one in which the cane
extract is separated by straining from the molasses, is about twenty
cubits long by ten wide; another, about thirty cubits long, by eight
wide, is that in which, after the extract has been strained, boiled and
clarified, the treacle is separated from the sugar by an operation
analogous to claying.

Each sugar manufacturer has a warehouse besides, of a size proportional
to the number of his boilers.

About 960 pounds of pot extract being divided into four parts, each is
put into a bag of coarse sackcloth, hung over an equal number of
wide-mouthed earthen vessels, and is besprinkled with a little water.
These drain from the bags about 240 lbs. of a substance analogous to
West Indian molasses. The remainder in the bags is a kind of coarse
muscovado sugar; but is far from being so well drained and freed from
molasses as that of the Antilles. The 720 lbs. of this substance are
then put into a boiler with 270 pounds of water, and the mixture is
boiled briskly for 144 minutes, when 180 additional pounds of water are
added, and the boiling is continued for 48 minutes more. An alkaline
solution is prepared from the ashes of the plantain tree, strewed over
straw placed in the bottom of an earthen pot perforated with holes.
Ninety pounds of water are passed through; and 6 pounds of the clear
lixivium are added to the boiling syrup, whereby a thick scum is raised,
which is removed. After 24 minutes, four and a half pounds of alkaline
solution, and about two-fifths of a pound of raw milk, are added; after
which the boiling and skimming are continued 24 minutes. This must be
repeated from five to seven times, until no more scum appears. 240
pounds of water being now added, the liquor is to be poured into a
number of strainers. These are bags of coarse cotton cloth, in the form
of inverted quadrangular pyramids, each of which is suspended from a
frame of wood, about 2 feet square. The operation of straining occupies
about 96 minutes. The strained liquor is divided into three parts: one
of these is put into a boiler, with from half a pound to a pound and a
half of alkaline solution, one-twelfth of a pound of milk, and 12 pounds
of water. After having boiled for between 48 and 72 minutes, three
quarters of a pound of milk are added, and the liquor is poured, in
equal portions, into four refining pots. These are wide at the mouth,
and pointed at the bottom; but are not conical, for the sides are
curved. The bottom is perforated, and the stem of a plantain leaf forms
a plug for closing the aperture. The two remaining portions of the
strained liquor are managed in exactly the same manner; so that each
refining pot has its share of each portion. When they have cooled a
little, the refining pot is removed to the curing-house, and placed on
the ground for 24 hours; next day they are placed on a frame, which
supports them at some distance from the ground. A wide-mouthed vessel is
placed under each, to receive the viscid liquor that drains from them.
In order to draw off this more completely, moist leaves of the
_Valisneria spiralis_ are placed over the mouth of the pot, to the
thickness of two inches; after 10 or 12 days, these are removed; when a
crust of sugar, about half an inch in thickness is found on the surface
of the boiled liquor. The crust being broken and removed, fresh leaves
are repeatedly added, until the whole sugar has formed; which requires
from 75 to 90 days. When cake extract is used, it does not require to be
strained before it be put into the boiler.

On the above-described operose and preposterous process, it is needless
to make any remarks. While it is adhered to with the tenacity of Hindu
habit, the West Indies has no reason to fear the competition of the
East, in the manufacture of sugar, provided the former avail themselves
of the aids which chemical and mechanical science are ready to supply.

In every part of the Behar and Putna districts, several of the
confectioners prepare the coarse article called _shukkur_, which is
entirely similar in appearance to the inferior Jamaica sugars. They
prepare it by putting some of the thin extract of sugar cane into coarse
sackcloth bags, and by laying weights on them, they squeeze out the
molasses; a process perfectly analogous to that contemplated in several
English patents.

[Illustration: 1082]

The sugar-mill at Chica Ballapura is worked by a single pair of
buffaloes or oxen, _fig._ 1082., going round with the lever A, which is
fixed on the top of the right-hand roller. The two rollers have endless
screw heads B, which are formed of 4 spiral grooves and 4 spiral ridges,
cut in opposite directions, which turn into one another, when the mill
is working. These rollers and their heads are of one piece, made of the
toughest and hardest wood that can be got, and such as will not impart
any bad taste to the juice. They are supported in a thick strong wooden
frame, and their distance from each other is regulated by means of
wedges, which pass through mortises in the frame planks, and a groove
made in a bit of some sort of hard wood, and press upon the axis of one
of the rollers. The axis of the other presses against the left-hand side
of the hole in the frame-boards. The cane juice runs down the rollers,
and through a hole in the lower frame-board, into a wooden conductor,
which carries it into an earthen pot. Two long-pointed stakes or piles
are driven into the earth, to keep the mill steady, which is all the
fixing it requires. The under part of the lowermost plank of the frame
rests upon the surface of the ground, which is chosen level and very
firm, that the piles may hold the faster. A hole is dug in the earth,
immediately below the spout of the conductor, to receive the pot.

The mill used in Burdwan and near Calcutta, is simply two small wooden
cylinders, grooved, placed horizontally, close to each other, and turned
by two men, one at each end. This simple engine is said completely, but
slowly, to express the juice. It is very cheap, the prime cost not being
two rupees; and being easily moved from field to field, it saves much
labour in the carriage of the cane. Notwithstanding this advantage, so
rude a machine must leave a large proportion of the richest juice in the
cane-trash.

It is curious to find in the antient arts of Hindostan exact prototypes
of the sugar-rollers, horizontal and upright, of relatively modern
invention in the New World.

[Illustration: 1083]

The sugar-mill of Chinapatam, _fig._ 1083., consists of a mortar, lever,
pestle, and regulator. The mortar is a tree about 10 feet in length, and
14 inches in diameter: _a_ is a plan of its upper end; _b_ is an outside
view; and _c_ is a vertical section. It is sunk perpendicularly into the
earth, leaving one end two feet above the surface. The hollow is
conical, truncated downwards, and then becomes cylindrical, with a
hemispherical projection in its bottom, to allow the juice to run freely
to the small opening that conveys it to a spout, from which it falls
into an earthen pot. Round the upper mouth of the cone is a circular
cavity, which collects any of the juice that may run over from the upper
ends of the pieces of cane; and thence a canal conveys this juice, down
the outside of the mortar, to the spout. The beam _d_, is about sixteen
feet in length, and six inches in thickness, being cut out from a large
tree that is divided by a fork into two arms. In the fork an excavation
is made for the mortar _b_, round which the beam turns horizontally. The
surface of this excavation is secured by a semicircle of strong wood.
The end towards the fork is quite open, for changing the beam without
trouble. On the undivided end of the beam sits the bullock-driver _e_,
whose cattle are yoked by a rope which comes from the end of the beam;
and they are prevented from dragging out of the circle by another rope,
which passes from the yoke to the forked end of the beam. On the arms
_f_, a basket is placed, to hold the cuttings of cane; and between this
and the mortar sits the man who feeds the mill. Just as the pestle comes
round, he places the pieces of cane sloping down into the cavity of the
mortar; and after the pestle has passed, he removes those that have been
squeezed.

OF THE MANUFACTURE OF SUGAR IN THE WEST INDIES.

Cane-juice varies exceedingly in richness, with the nature of the soil,
the culture, the season, and variety of the plant. It is an opaque
fluid, of a dull gray, olive, or olive-green colour; in taste, balmy and
saccharine; exhaling the balsamic odour of the cane; slightly viscid;
and of a specific gravity varying from 1·033 to 1·106, according to
circumstances. When fresh, it consists of two parts; the one liquid, the
other solid; the latter of which being merely suspended in the former,
and, therefore, separable in a great measure by filtration or repose.
The solid matter consists of fragments of the cellular parenchyma of the
cane, its fibres, and bark, mechanically protruded through the mill;
mixed with a very abundant greenish substance, like that called
_chlorophyle_ by chemists.

When left to itself in the colonial climates, the juice runs rapidly
into the acetous fermentation; twenty minutes being, in many cases,
sufficient to bring on this destructive change. Hence arises the
necessity of subjecting it immediately to clarifying processes, speedy
in their action. When deprived of its green fecula and glutinous
extractive, it is still subject to fermentation; but this is now of the
vinous kind. The juice flows from the mill through a wooden gutter lined
with lead, and being conducted into the sugar-house, is received in a
set of large pans or caldrons, called clarifiers. On estates which make
on an average, during crop time, from 15 to 20 hogsheads of sugar a
week, three clarifiers, of from 300 to 400 gallons’ capacity each, are
sufficient. With pans of this dimension, the liquor may be drawn off at
once by a stopcock or syphon, without disturbing the feculencies after
they subside. Each clarifier is hung over a separate fire, the flue
being furnished with a damper for checking the combustion, or
extinguishing it altogether. The clarifiers are sometimes placed at one
end, and sometimes in the middle of the house, particularly if it
possesses a double set of evaporating pans.

Whenever the stream from the mill cistern has filled the clarifier with
fresh juice, the fire is lighted, and the _temper_, or dose of slaked
lime, diffused uniformly through a little juice, is added. If an
albuminous emulsion be used to promote the clarifying, very little lime
will be required; for recent cane-liquor contains no appreciable portion
of acid to be saturated. In fact, the lime and alkalies in general, when
used in small quantity, seem to coagulate the glutinous extractive
matter of the juice, and thus tend to brighten it up. But if an excess
of temper be used, the gluten is taken up again by the strong affinity
which is known to exist between sugar and lime. Excess of lime may
always be corrected by a little alum-water. Where canes grow on a
calcareous marly soil, in a favourable season the saccharine matter gets
so thoroughly elaborated, and the glutinous mucilage so completely
condensed, that a clear juice and a fine sugar may be obtained without
the use of lime.

As the liquor grows hot in the clarifier, a scum is thrown up,
consisting of the coagulated feculencies of the cane-juice. The fire is
now gradually urged till the temperature approaches the boiling point;
to which, however, it must not be suffered to rise. It is known to be
sufficiently heated, when the scum rises in blisters, which break into
white froth; an appearance observable in about forty minutes after
kindling the fire. The damper being shut down, the fire dies out; and
after an hour’s repose, the clarified liquor is ready to be drawn off
into the last and largest in the series of evaporating pans. In the
British colonies, these are merely numbered 1, 2, 3, 4, 5, beginning at
the smallest, which hangs right over the fire, and is called the
_teache_; because in it the trial of the syrup, by _touch_, is made. The
flame and smoke proceed in a straight line along a flue to the
chimney-stalk at the other end of the furnace. The area of this flue
proceeds, with a slight ascent from the fire, to the aperture at the
bottom of the chimney; so that between the surface of the grate and the
bottom of the teache, there is a distance of 28 inches; while between
the bottom of the flue and that of the _grand_, No. 5., at the other end
of the range, there are barely 18 inches.

In some sugar-houses there is planted, in the angular space between each
boiler, a basin, one foot wide and a few inches deep, for the purpose of
receiving the scum which thence flows off into the _grand copper_, along
a gutter scooped out on the margin of the brickwork. The skimmings of
the _grand_ are thrown into a separate pan, placed at its side. A large
cylindrical _cooler_, about 6 feet wide and 2 feet deep, has been placed
in certain sugar-works near the teache, for receiving successive charges
of its inspissated syrup. Each finished charge is called a skipping,
because it is skipped or laded out. The term _striking_ is also applied
to the act of emptying the _teache_. When upon one skipping of syrup in
a state of incipient granulation in the cooler, a second skipping is
poured, this second congeries of saccharine particles agglomerates round
the first as _nuclei_ of crystallization, and produces a larger grain; a
result improved by each successive skipping. This principle has been
long known to the chemist, but does not seem to have been always
properly considered or appreciated by the sugar-planter.

From the above described _cooler_, the syrup is transferred into wooden
chests or boxes, open at top, and of a rectangular shape; also called
_coolers_, but which are more properly crystallizers or granulators.
These are commonly six in number; each being about one foot deep, seven
feet long, and five or six feet wide. When filled, such a mass is
collected, as to favour slow cooling, and consequent large-grained
crystallization. If these boxes be too shallow, the grain is exceedingly
injured, as may be easily shown by pouring some of the same syrup on a
small tray; when, on cooling, the sugar will appear like a muddy soft
sand.

The criterion by which the negro boilers judge of the due concentration
of the syrup in the teache, is difficult to describe, and depends almost
entirely on the sagacity and experience of the individual. Some of them
judge by the appearance of the incipient grain on the back of the
cooling ladle; but most decide by “_the touch_,” that is, the feel and
appearance of a drop of the syrup pressed and then drawn into a thread
between the thumb and fore-finger. The thread eventually breaks at a
certain limit of extension, shrinking from the thumb to the suspended
finger, in lengths somewhat proportional to the inspissation of the
syrup. But the appearance of granulation in the thread must also be
considered; for a viscid and damaged syrup may give a long enough
thread, and yet yield almost no crystalline grains when cooled. Tenacity
and granular aspect must therefore be both taken into the account, and
will continue to constitute the practical guides to the negro boiler,
till a less barbarous mode of concentrating cane-juice be substituted
for the present _naked teache_, or _sugar frying-pan_.

That weak sugars are such as contain an inferior proportion of carbon in
their composition, was first deduced by me from my experiments on the
ultimate analysis of vegetable and animal bodies; an account of which
was published in the Philosophical Transactions of the Royal Society for
1822. Since then Dr. Prout has arrived at results comfirmatory of my
views. See Philosophical Transactions for 1827. Thus, he found pure
sugar-candy, and the best refined sugar, to contain 42·85 parts of
carbon per cent.; East India sugar-candy, 41·9 parts; East India raw
sugar in a thoroughly dry state, but of a low quality, 40·88; manna
sugar, well refined, 28·7; sugar from Narbonne honey, 36·36; sugar from
starch, 36·2. Hence, by _caramelizing_ the syrup in the _teache_, not
only is the crystallizable sugar blackened, but its faculty of
crystallizing impaired, and the granular portion rendered weaker.

A viscous syrup containing much gluten and sugar, altered by lime,
requires a higher temperature to enable it to granulate, than a pure
saccharine syrup; and therefore the thermometer, though a useful
adjuvant, can by no means be regarded as a sure guide, in determining
the proper instant for _striking_ the _teache_.

The colonial _curing-house_ is a capacious building, of which the
earthen floor is excavated to form the molasses reservoir. This is lined
with sheet lead, boards, tarras, or other retentive cement; its bottom
slopes a little, and it is partially covered by an open massive frame of
joist-work, on which the potting casks are set upright. These are merely
empty sugar hogsheads, without headings, having 8 or 10 holes bored in
their bottoms, through each of which the stalk of a plantain leaf is
stuck, so as to protrude downwards 6 or 8 inches below the level of the
joists, and to rise above the top of the cask. The act of transferring
the crude concrete sugar from the crystallizers into these hogsheads, is
called potting. The bottom holes, and the spongy stalks stuck in them,
allow the molasses to drain slowly downwards into the sunk cistern. In
the common mode of procedure, sugar of average quality is kept from 3 to
4 weeks in the curing-house; that which is soft-grained and glutinous,
must remain 5 or 6 weeks. The curing-house should be close and warm, to
favour the liquefaction and drainage of the viscid caramel.

Out of 120 millions of pounds of raw sugar, which used to be annually
shipped by the St. Domingo planters, only 96 millions were landed in
France, according to the authority of Dutrone, constituting a loss by
drainage in the ships of 20 per cent. The average transport waste at
present in the sugars of the British colonies cannot be estimated at
less than 12 per cent., or altogether upwards of 27,000 tons! What a
tremendous sacrifice of property!

Within these few years a very considerable quantity of sugar has been
imported into Great Britain in the state of concentrated cane-juice,
containing nearly half its weight of granular sugar, along with more or
less molasses, according to the care taken in the boiling operations. I
was at first apprehensive that the syrup might undergo some change on
the voyage; but among more than a hundred samples which I have analyzed
for the custom-house, I have not perceived any traces of fermentation.
Since sugar softens in its grain at each successive solution, whatever
portion of the crop may be destined for the refiner, should upon no
account be granulated in the colonies; but should be transported in the
state of a rich cane-syrup to Europe, transferred at once into the
blowing-up cistern, subjected there to the reaction of bone black, and
passed through bag-filters, or through layers of the coarsely ground
black, previously to its final concentration in the vacuum pan. Were
this means generally adopted, I am convinced that 30 per cent. would be
added to the amount of home-made sugar loaves corresponding to a given
quantity of average cane-juice; while 30 per cent., would be taken from
the amount of molasses. The saccharine matter now lost by drainage from
the hogsheads in the ships, amounting to from 10 to 15 per cent., would,
also be saved. The produce of the cane would, on this plan, require less
labour in the colonies, and might be exported 5 or 6 weeks earlier than
at present, because the period of drainage in the curing-house would be
spared.

It does not appear that our sugar colonists have availed themselves of
the proper chemical method of counteracting that incipient fermentation
of the cane-juice, which sometimes supervenes, and proves so injurious
to their products. It is known that grape-must, feebly impregnated with
sulphurous acid, by running it slowly into a cask in which a few sulphur
matches have been burned, will keep without alteration for a year; and
if _must_, so _muted_, is boiled into a syrup within a week or ten days,
it retains no sulphureous odour. A very slight muting would suffice for
the most fermentable cane-juice: and it could be easily given, by
burning a sulphur match within the cistern immediately before charging
it from the mill. The cane-juice should, in this case, be heated in the
clarifier, so as to expel the sulphurous acid, before adding the temper
lime; for otherwise a little calcareous sulphite might be introduced
into the sugar. Thus the arescence so prejudicial to the saccharine
granulation would be certainly prevented.

An ACCOUNT of SUGAR Imported into the United Kingdom during the years
ending 5th January, 1837, and 5th January, 1838.

  +------------------------------+-----------------------------------+
  |                              |        Quantities imported.       |
  |                              +-----------------+-----------------+
  |                              |      1837.      |      1838.      |
  |                              +-----------------+-----------------+
  |                              |   Cwt.   qr. lb.|   Cwt.   qr. lb.|
  |Sugar, unrefined; viz.--of    |                 |                 |
  |the British possessions in    |                 |                 |
  |America                       |3,600,516  3   2 |3,304,092  2   2 |
  |Of Mauritius                  |  497,303  0   8 |  537,054  1  21 |
  |East India British possessions|  152,229  1  13 |  296,677  2  12 |
  |East India Foreign possessions|   71,464  2   0 |   77,090  0  18 |
  |Other sorts                   |  327,647  1  12 |  266,559  2  24 |
  |                              +-----------------+-----------------+
  |Total                         |4,649,161  0   7 |4,481,474  1  21 |
  +------------------------------+-----------------+-----------------+

  +------------------------------+-----------------------------------+
  |                              |    Quantities entered for Home    |
  |                              |            Consumption.           |
  |                              +-----------------+-----------------+
  |                              |      1837.      |      1838.      |
  |                              +-----------------+-----------------+
  |                              |   Cwt.   qr. lb.|   Cwt.   qr. lb.|
  |Sugar, unrefined; viz.--of    |                 |                 |
  |the British possessions in    |                 |                 |
  |America                       |3,296,641  1  19 |3,562,703  1  24 |
  |Of Mauritius                  |  518,228  0   5 |  522,348  3  11 |
  |East India British possessions|  110,236  2   0 |  270,146  1   2 |
  |East India Foreign possessions|       20  3  18 |        3  3  11 |
  |Other sorts                   |       31  1   6 |       37  3  10 |
  |                              +-----------------+-----------------+
  |Total                         |3,925,140  0  20 |4,355,240  1   2 |
  +------------------------------+-----------------+-----------------+

  +------------------------------+---------------------+
  |                              |Gross amount of Duty |
  |                              |      received.      |
  |                              +----------+----------+
  |                              |  1837.   |  1838.   |
  |                              +----------+----------+
  |                              |   _£_.   |   _£_.   |
  |Sugar, unrefined; viz.--of    |          |          |
  |the British possessions in    |          |          |
  |America                       |3,956,879 |4,275,207 |
  |Of Mauritius                  |  621,596 |  626,131 |
  |East India British possessions|  176,376 |  368,672 |
  |East India Foreign possessions|       66 |       12 |
  |Other sorts                   |       41 |       95 |
  |                              +----------+----------+
  |Total                         |4,754,958 |5,270,117 |
  +------------------------------+----------+----------+

An ACCOUNT of SUGAR Exported in the year ended 5th January, 1838,
compared with the Exports of the preceding Year.

  +----------------------+-----------------+-----------------+
  |                      |      1837.      |      1838.      |
  |                      +-----------------+-----------------+
  |                      | Cwts.  qrs. lbs.| Cwts.  qrs. lbs.|
  |Sugar, of the British |                 |                 |
  |          possessions |                 |                 |
  |          in America  |  8,774   1  15  |  9,267   0  21  |
  |          Mauritius   |  2,687   3  14  |  3,065   0  19  |
  |       East India, of |                 |                 |
  |       British posses-|                 |                 |
  |       sions          | 22,290   3  16  | 13,283   0  22  |
  |       Foreign posses-|                 |                 |
  |       sions          | 52,384   0   4  | 68,252   2  18  |
  |       Other sorts    |191,961   0  20  |354,513   1  23  |
  +----------------------+-----------------+-----------------+

Syrup intended for forming clayed sugar must be somewhat more
concentrated in the teache, and run off into a copper cooler, capable of
receiving three or four successive skippings. Here it is stirred to
ensure uniformity of product, and is then transferred by ladles into
conical moulds, or _formes_, made of coarse pottery, having a small
orifice at the apex, which is stopped with a plug of wood wrapped in a
leaf of maize. These pots are arranged with the base upwards. As their
capacity, when largest, is greatly less than that of the smallest
potting-casks, and as the process lasts several weeks, the claying-house
requires to have very considerable dimensions. Whenever the syrup is
properly granulated, which happens usually in about 18 or 20 hours, the
plugs are removed from the apices of the cones, and each is set on an
earthen pot to receive the drainings. At the end of 24 hours, the cones
are transferred over empty pots, and the molasses contained in the
former ones is either sent to the fermenting-house or sold. The claying
now begins, which consists in applying to the smoothed surface of the
sugar at the base of the cone, a plaster of argillaceous earth, or
tolerably tenacious loam in a pasty state. The water diffused among the
clay escapes from it by slow infiltration, and descending with like
slowness through the body of the sugar, carries along with it the
residuary viscid syrup which is more readily soluble than the granulated
particles. Whenever the first magma of clay has become dry, it is
replaced by a second; and this occasionally in its turn by a third,
whereby the sugar cone gets tolerably white and clean. It is then dried
in a stove, cut transversely into _frusta_, crushed into a coarse powder
on wooden trays, and shipped off for Europe. Clayed sugars are sorted
into different shades of colour according to the part of the cone from
which they were cut; under the denomination in French commerce of
_premier_, _second_, _troisième_, _petit_, _commun_, and _tête_; the
last or the tip being an indifferent article. The clayed sugar of Cuba
is called Havannah sugar, from the name of the shipping port.

Clayed sugar can be made only from the ripest cane-juice, for that which
contains much gluten would be apt to get too much burned by the ordinary
process of boiling, to bear the claying operation. The syrups that run
off from the second, third, and fourth application of the clay-paste,
are concentrated afresh in a small building apart, called the refinery,
and yield tolerable sugars. Their drainings go to the molasses cistern.
The cones remain for 20 days in the claying-house, before the sugar is
taken out of them.

Claying is seldom had recourse to in the British plantations, on account
of the increase of labour, and diminution of weight in the produce, for
which the improvement in quality yields no adequate compensation. Such,
however, was the esteem in which the French consumers held clayed sugar,
that it was prepared in 400 plantations of St. Domingo alone.

SUGAR REFINING.

Raw, or muscovado sugar, as imported from the colonies, is contaminated
more or less with gluten, lime, but particularly _caramel_, which give
its grains a yellow brown tint, an empyreumatic odour, and a soft clammy
feel in the hand. If such sugar be dissolved in water, and the syrup be
evaporated by a gentle heat, it will afford a sugar of still inferior
quality and appearance. This rapid deterioration is in some measure
owing to the injurious operation of a prolonged heat upon the
crystalline structure, but chiefly to the chemical reaction of the
glutinous ferment and lime upon the sugar. The first care of the refiner
should therefore be the immediate abstraction of these noxious
alteratives, which he effects by the process called _meltings_; that is,
mixing up the sugar in a pan with hot water or steam into a pap, and
transferring this pap into large sugar-moulds. Whenever these become
cool, their points are unplugged, and they are set to drain for a few
days in a warm apartment. Sugar thus cleansed is well prepared for the
next refining process; which consists in putting it into a large square
copper cistern along with some lime-water, (a little bullock’s blood,)
and from 5 to 20 per cent. of bone black, and blowing it up with steam;
or, in other words, injecting steam through the mixture from numerous
orifices in copper pipes laid along the bottom and sides of the vessel.
Under the influence of the heat and agitation thus occasioned, the
saccharine matter is perfectly dissolved and incorporated with the
albumen of the blood and the bone black. Instead of the blood, many
refiners employ a mixture of gelatinous alumina and gypsum, called
_finings_, prepared by adding a solution of alum to a body of
lime-water, collecting, washing, and draining the precipitate upon a
filter. Other refiners use both the blood and finings, with advantage.
Bone black is now very frequently employed by the sugar-refiner, not in
a fine meal, but in a granular state, like corned gunpowder, for the
purpose of decolouring his syrups; in which case, he places it in a box,
in a stratum 8 or 10 inches thick, and makes the syrup percolate
downwards through it, into a cistern placed beneath. By this means it is
deprived of colour, and forms the _claircé_ of the French refiner. When
the blowing up cistern is charged with sugar, finely ground bone black,
and blood, the mixture must be passed through a proper system of
filters. That now most in use is the creased bag filter, represented in
_figs._ 1084, 1085, 1086.

[Illustration: 1084 1085 1086]

The apparatus consists of an upright square wooden case _a_, _a_, about
6 or 8 feet high, furnished with a door of admission to arrange the
interior objects; beneath is a cistern with an educting-pipe for
receiving and carrying off the filtered liquor; and above the case is
another cistern _e_, which, like the rest, is lined with tinned sheet
copper. Into the upper cistern, the syrup mixed with animal charcoal is
introduced, and passes thence into the mouths _e_, _e_, of the several
filters _d_, _d_. These consist, each of a bag of thick tweeled cotton
cloth, about 12 or 15 inches in diameter, and 6 or 8 feet long, which is
inserted into a narrow bottomless bag of canvas, about 5 inches in
diameter, for the purpose of folding the filter-bag up into a small
space, and thus enabling a great extent of filtering surfaces to be
compressed into one box. The orifice of each compound bag is tied round
a conical brass month-piece or nozzle _e_, which screws tight into a
corresponding opening in the copper bottom of the upper cistern. From 40
to 60 bags are mounted in each filter case. The liquor which first
passes is generally tinged a little with the bone black, and must be
pumped back into the upper cistern, for refiltration. In cold weather
the interior of the case may be kept warm by a proper distribution of
steam-pipes. _Fig._ 1085. shows one mode of forming the funnel-shaped
nozzles of the bags, in which they are fixed by a bayonet catch. _Fig._
1086. shows the same made fast by means of a screwed cap, which is more
secure.

The next process in sugar-refining is the evaporation of the clarified
syrup to the granulating or crystallizing pitch. The more rapidly this
is effected, and with the less scorching injury from fire, the better
and greater is the product in sugar-loaves. No apparatus answers the
refiner’s double purpose of safety and expedition so well as the
vacuum-pan of Howard.

[Illustration: 1087]

_Fig._ 1087. shows the structure of a single vacuum-pan. The horizontal
diameter of the copper spheroid A, is not less than 5 feet; the depth of
the under hemisphere is at least 18 inches from the level of the plane;
and the height of the dome-cover is 2 feet. The two hemispheres (of
which the inferior one is double, or has a steam-jacket,) are put
together by bolts and screws, with packing between the flanges to
preserve the joints tight against atmospheric pressure. The jacket of
the lower hemisphere forms the case of the steam, which communicates
heat to the syrup enclosed in the inner hemisphere. In general, the pans
contain, when filled to the flange, 100 gallons of syrup, and yield
about 11 cwt. of granulated sugar, at every charge.

A, represents the vacuum spheroid; B, the neck with the lid. From the
side of B, a pipe passes into the lower extremity of the bent pipe C, D,
which terminates in the vertical pipe E, connected with the vacuum
main-pipe K, proceeding horizontally from the air-pump (not shown in the
figure). At the top of E, a valve, movable by a screw H, is placed for
establishing or cutting off the connexion with the air-pump at pleasure.
Behind F, is the measure cistern, from which the successive charges are
admitted into the pan. This measure is filled with the clear syrup, by
opening the stopcock I, on the pipe under the ceiling, which
communicates with the filter-cistern placed above. G is the valve or
plug-hole, at the bottom of the pan, for discharging the granulating
syrup. This plug is opened by means of a powerful lever attached to it;
the connexion with the air-pump being previously intercepted. L, is the
barometer, or manometer, for showing the state of the vacuum
corresponding to the temperature. N, N, is a cistern-pipe for receiving
any little syrup which may accidentally boil over the neck B. Its
contents are let off by a stopcock at its bottom from time to time. M
shows the place of the _proof-stick_, an ingenious brass rod for taking
out a sample of syrup without admitting air. See _infrà_.

The charging-cistern contains about 20 gallons. This quantity of syrup
being first admitted, and brought to a certain pitch of concentration, a
second measure is introduced, the inspissation of which is supposed by
some refiners to cause an agglomeration of saccharine matter round the
first crystalline particles. The repetition of this process for two or
three times is imagined to produce the large brilliant grain of
vacuum-pan sugar. This hypothesis is more specious than sound, because
the granulating syrup discharged from the pan is subjected to a heat of
180° or 190° in the subjacent steam-cased receiver, whereby the
granulations are again reduced to a very small size. Into this receiver,
two or three skippings or discharges of the pan are admitted in
succession, and the whole are diligently mixed and agitated by a
stirring oar. It is by this process that the granulating tendency is
promoted and determined. From this receiver (absurdly enough called a
cooler) the moulds are filled in the usual way, by means of copper
basins or large ladles.

The case of the under hemisphere of the vacuum-pan is filled with steam,
generated under a pressure of four or five pounds on the square inch;
the heat of which causes the interior syrup to boil rapidly while the
air-pump is kept in action. A small escape-pipe for waste steam must be
placed at the opposite side of the case or jacket, to ensure its equal
distribution; as also a stopcock below, to let off the water of
condensation. The pans are mounted on iron feet, or short pillars, which
insulate them from the floor, and allow their whole surface to be
inspected, and any flaw to be repaired. The air-pump usually stands in a
cold-water cistern, to favour the condensation of the aqueous vapour,
which it draws out of the pans; and it is kept in constant action by the
steam-engine, being attached to the working-beam of its piston.

[Illustration: 1088]

_Fig._ 1088. exhibits the general arrangement of the vacuum-pans, and
their subsidiary apparatus. Here are shown, on the ground floor, the
heaters _e_, _e_, (miscalled coolers), into which the concentrated syrup
is let down. These heaters are made of copper, in one piece, surrounded
with a cast-iron jacket, bolted at the flange or brim to it. Each pan
contains, when full, about 350 gallons, equivalent to nearly 35 cwt. of
crystallized sugar. They are furnished with steam-cocks and waste
steam-pipes. Under the level of the spheroids _d_, _d_, the horizontal
main-pipe is seen, for supplying the cases with steam. In the face of
each pan, above the line _b_, _b_, the handle of the proof-stick
appears, like that of a stop-cock. The distribution of the measure
cisterns, and some other parts of the pans, is slightly varied in this
representation from the former. From the bottom of the liquor cisterns
C, C, pipes descend to the charging measures _a_, _a_, below. The
cisterns C, C, are made of copper, and contain each about 400 gallons.
Six tons of refined sugar can be turned out daily in a three-pan house.

[Illustration: 1089]

_Fig._ 1089. represents in section another form of the vacuum-pan, _a_
is the spheroidal copper vessel, supported by four iron columns _b_,
_b_. It may be discharged by means of the pipe _c_, which is secured
with a conical valve _d_. This may be opened or shut, by acting on the
lever _e_. The lower of the two hemispheres of which the pan is
composed is double, and the interstitial space _f_, _f_, is filled with
steam by the pipe _g_, as the heating and evaporating agent. _h_, is the
steam valve; _i_, the pipe for the efflux of the condensed water. _k_, a
tube for the escape of the air at the commencement of the operation.
_l_, is an apparatus inserted air-tight into the cover of the
vacuum-pan, and which dips down into the syrup; serving to take out a
sample of it, without allowing air to enter, and hence called the
proof-stick. The construction of this instrument is exhibited in _figs._
1091, 1092, 1093, 1094, 1095., which will be presently explained. _m_,
is the thermometer, which is also plunged into the sugar; behind it, is
the barometer. _n_, is the charger or gauge-vessel, filled with the
filtered syrup, which it discharges by the pipe _n´_. _o_, is the cover
or capital of the vacuum-pan. _o´_, is a safety-valve, through which the
air may be admitted, after the completion of the process. _p_, is a bent
pipe, slanting downwards, with a stopcock _q_, at its end, to receive
the superfluous syrup. The vapour, which is disengaged from the syrup
during its concentration, is extracted from the top of the pan into the
pipe _r_, passes from this into the vessel _s_, which is divided by a
plate of copper into two compartments. The syrup forced over
accidentally in the ebullition, goes into the vessel _s_, and passes by
the glass tube _t_, into the pipe _p_. The glass tube serves to show the
quantity of the syrup that has boiled over, so that it may be drawn off
when necessary. For this purpose, the stopcock _u_, of the vessel _v_,
must be closed, and _q_ must be opened, in order to fill _v_, while the
air contained in it escapes into the pan. The stopcock _q_, being then
shut, and _u_, with the little air-cock _x_, opened, the syrup will flow
into the large receiver placed beneath it, commonly but erroneously
called a cooler; because it is a double copper basin, with steam in the
interstitial space. The hot steam rushes from _s_, into the cast-iron
vessel _y_, where it is condensed. _z_, is a pipe for introducing the
water of condensation through the copper rose _a´_. The condensed water
flows through the pipe _b´_, and the valve _e´_, to the air-pump, which
receives motion from the shaft of the steam-engine.

[Illustration: 1090]

The vacuum-pan was originally heated solely by the admission of steam
between the double bottom; but of late years the heat has been also
applied to the syrup through several coils of pipe placed within the
pan, filled with steam at a temperature many degrees above 212° F.,
sometimes so high as 250°. By this double application of heat, the
evaporating power of a pan has been vastly increased. The latest made
pans have a considerably flat bottom, _fig._ 1090.; a spiral pipe, laid
close upon it; and between the under hemisphere and the upper one, there
is a space _a_, _a_, 2-1/2 feet high, to give the syrup room for
frothing up without boiling over. The space _b_, of the bottom receives
steam of common pressure, and the spiral tubes, of high pressure. A pan
like this is now making for a house in London, which is to work off 16
tons of sugar-loaves daily.

[Illustration: 1091 1092 1093 1094 1095]

The proof-stick, _fig._ 1095., consists of a cylindrical rod, capable of
being screwed air-tight into the pan in an oblique direction downwards.
The upper or exterior end is open; the under, which dips into the syrup,
is closed, and has on one side a slit _a_ (_figs._ 1091, 1092.), or
notch, about 1/2 inch wide. In this external tube, there is another
shorter tube _b_, capable of moving round in it, through an arc of 180°.
An opening upon the under end _e_, corresponds with the slit in the
outer tube, so that both may be made to coincide, _fig._ 1091. A. A
wooden plug _d_, is put in the interior tube, but so as not to shut it
entirely. Upon the upper end there is a projection or pin, which catches
in a slit of the inner tube, by which this may be turned round at
pleasure. In the lower end of the plug there is a hole _e_, which can be
placed in communication with the lateral openings in both tubes. Hence
it is possible, when the plug and the inner tube are brought into the
proper position, A, _fig._ 1091., to fill the cavity of the wooden rod
with the syrup, and to take it out without allowing any air to enter.
In order to facilitate the turning of the inner tube within the outer,
there is a groove in the under part, into which a little grease may be
introduced.

Whenever a proof has been taken, the wooden plug must be placed in
reference to the inner tube, as shown in _fig._ 1091. _c_, and then be
turned into the position A; when the cavity of the plug will again be
filled with syrup. _c_ must be now turned back to the former position,
whereby all intercourse with the vacuum-pan is cut off; the plug being
drawn out a little, and placed out of communication with the inner tube.
The plug is then turned into the position B, drawn out, and the proof
examined by the fingers.

TABLE showing the boiling point of syrup, at the corresponding
atmospheric pressure within the vacuum-pan:--

  Height of the mercury (inches) in one leg of the syphon, above
  that in the other--
  0·74 0·86 1·01 1·17 1·36 1·57 1·80 2·05 2·36 2·72 3·10 3·52 4·00.
  Boiling point, Fahr.--
  115° 120° 125° 130° 135° 140° 145° 150° 155° 160° 165° 170° 175°.

The large double steam-basin, which receives several successive
skippings of the concentrated granulating syrup, serves to heat it from
the temperature of 160° or 170°, at which it leaves the vacuum-pan, up
to 200° or thereby, before it is filled out into the moulds; for were it
introduced in the cooler state, it would not concrete into sufficiently
compact loaves.

[Illustration: 1096 1097]

The following apparatus is used in many French sugar-houses, for
concentrating syrups, called the _swing pan_, or _chaudière à bascule_.
It is represented in _fig._ 1096. in elevation, and in _fig._ 1097. in
ground plan. _a_, is the pan; _b_, its spout; _c_, the axis or pivot
round which it swings, so as to empty itself, when raised behind by the
chain _d_; _e_, is the furnace door; _f_, the passage to the fireplace
and grate _g_; _h_, _h_, _h_, side flues for conducting the smoke into
the chimney.

The duly clarified, concentrated, granulated, and reheated syrup, is
transferred, by means of copper basins, from the coolers into conical
moulds, made either of brown and somewhat porous earthenware, or of
sheet iron, strongly painted. The sizes of the moulds vary, from a
capacity of 10 pound _loaves_, to that of 56 pound _bastards_--a kind of
soft brown sugar obtained by the concentration of the inferior syrups.
These moulds have the orifices at their tips closed with bits of twisted
paper, and are set up in rows close to each other, in an airy apartment
adjoining the coolers. Here they are left several hours, commonly the
whole night, after being filled, till their contents become solid, and
they are lifted next morning into an upper floor, kept at a temperature
of about 80° by means of steam pipes, and placed each over a pot to
receive the syrup drainings--the paper plug being first removed, and a
steel wire, called a piercer, being thrust up to clear away any
concretion from the tip. Instead of setting the lower portion of the
inverted cones in pots, some refiners arrange them in wooden racks, with
their apices suspended over longitudinal gutters of lead or zinc, laid
with a slight slope upon the floor, and terminating in a sunk cistern.
The syrup which flows off spontaneously is called green syrup. It is
kept separate. In the course of two or three days, when the drainage is
nearly complete, some finely clarified syrup, made from loaf sugar,
called _liquor_ by the refiners, is poured to the depth of about an inch
upon the base of each cone, the surface having been previously rendered
level and solid by an iron tool, called a bottoming trowel. The liquor,
in percolating downwards, being already a saturated syrup, can dissolve
none of the crystalline sugar, but only the coloured molassy matter;
whereby, at each successive liquoring, the loaf becomes whiter, from the
base to the apex. A few moulds, taken promiscuously, are emptied from
time to time, to inspect the progress of the blanching operation; and
when the loaves appear to have acquired as much _colour_, according to
the language of refiners, as is wanted for the particular market, they
are removed from the moulds, turned on a lathe at the tips, if
necessary, set for a short time upon their bases, to diffuse their
moisture equally through them, and then transferred into a stove heated
to 130° or 140° by steam pipes, where they are allowed to remain for two
or three days, till they be baked thoroughly dry. They are then taken
out of the stove, and put up in blue paper for sale.

In the above description of sugar-refining, I have said nothing of the
process of claying the loaves, because it is now nearly obsolete, and
abandoned in all well-appointed sugar-houses. Those of my readers who
desire to become acquainted with sugar-refining upon the old plan, may
consult my Report made upon the subject to the Honourable HOUSE of
COMMONS in July 1833; where they will find every step detailed, and the
numerical results stated with minute accuracy. The experiments
subservient to that official report were instituted purposely to
determine the average yield or product, in double and single refined
loaves, lumps, bastards and treacle, which different kinds of sugar
would afford per cwt., when refined by decolouring with not more than 5
per cent. of bone black, boiling in an open pan, and clearing the loaves
with clay-pap.

BEET-ROOT SUGAR.

The physical characters which serve to show that a beet-root is of good
quality, are its being firm, brittle, emitting a creaking noise when
cut, and being perfectly sound within; the degree of sweetness is also a
good indication. The 45th degree of latitude appears to be the southern
limit of the successful growth of beet in reference to the extraction of
sugar.

_Extraction of Sugar from the Beet._--The first manipulations to which
the beets are exposed, are intended to clear them from the adhering
earth and stones, as well as the fibrous roots and portions of the neck.
It is desirable to expose the roots, after this operation, to the action
of a cylinder washing-machine.

The parenchyma of the beet is a spongy mass, whose cells are filled with
juice. The cellular tissue itself, which forms usually only a twentieth
or twenty-fifth of the whole weight, consists of ligneous fibre.
Compression alone, however powerful, is inadequate to force out all the
liquor which this tissue contains. To effect this object, the roots must
be subjected to the action of an instrument which will tear and open up
the greatest possible number of these cells. Experiments have, indeed,
proved, that by the most considerable pressure, not more than 40 or 50
per cent. in juice from the beet can be obtained; whilst the pulp
procured by the action of a grater produces from 75 to 80 per cent.

[Illustration: 1098 1099]

The beet-root rasp of Moulfarine is represented in _figs._ 1098, 1099.
_a_, _a_, is the frame-work of the machine; _b_, the feed-plate made of
cast iron, divided by a ridge into two parts; _c_, the hollow drum; _d_,
its shaft, upon either side of whose periphery nuts are screwed for
securing the saw blades _e_, _e_, which are packed tight against each
other by means of laths of wood; _f_, is a pinion upon the shaft of the
drum, into which the wheel _g_ works, and which is keyed upon the shaft
_h_; _i_, is the driving rigger; _k_, pillar of support; _l_, blocks of
wood, with which the workman pushes the beet-roots against the
revolving-rasp; _m_, the chest for receiving the beet-pap; _n_, the
wooden cover of the drum, lined with sheet iron. The drum should make
500 or 600 turns in the minute.

A few years ago, M. Dombasle introduced a process of extracting the
juice from the beet without either rasping or hydraulic pressure. The
beets were cut into thin slices, by a proper rotatory blade-machine;
these slices were put into a macerating cistern, with about their own
bulk of water, at a temperature of 212° F. After half an hour’s
maceration, the liquor was said to have a density of 2° B., when it was
run off into a second similar cistern, upon other beet-roots; from the
second, it was let into a third, and so on to a fifth; by which time,
its density having risen to 5-1/2°, it was ready for the process of
defecation. Juice procured in this way is transparent, and requires
little lime for its purification; but it is apt to ferment, or to have
its granulating power impaired by the watery dilution. The process has
been accordingly abandoned in most establishments.

I have seen the following operations successfully executed in a
beet-root factory near Lille, and have since verified their propriety in
my own laboratory upon white beets, grown near Mitcham in Surrey. My
product was nearly 5 per cent.; it was very fair, and large grained,
like the vacuum-pan sugar of Demerara, but without its clamminess.

The roots were washed by a rotatory movement upon a grating made like an
Archimedes’ screw, formed round the axis of a squirrel-cage cylinder,
which was laid horizontally beneath the surface of water in an oblong
trough. It was turned by hand rapidly, with the intervention of a
toothed wheel and pinion. The roots, after being sufficiently agitated
in the water, were tossed out by the rotation at the end of the cylinder
furthest from the winch. They were next hoisted in a basket up through a
trap hole into the floor above, by means of a cord and pulley moved by
mechanical power; a six-horse steam engine, upon Woolfe’s expansive
principle, being employed to do all the heavy work. They were here
subjected to the mechanical grater (_rape mécanique_), see _fig._ 1098,
1099., which had, upon its sloping feed-table, two square holes for
receiving at least two beets at a time, which were pushed forwards by a
square block of wood held in the workman’s hand by means of a strap. The
rasp was a drum, having rows of straight saws placed half an inch apart
round its periphery, _parallel to the axis_, with teeth projecting about
1/8 of an inch. The space between each pair of saws was filled with a
wedge of wood. The steel slips, or saw plates, were half an inch broad,
twelve inches long, and serrated on both their longitudinal edges, so
that when the one line of teeth was blunted, the other could be turned
out. The drum made 750 turns per minute.

The pulp from the rasp fell into a flat trough placed beneath, whence it
was shovelled into small bags. Each bag had its mouth folded over, was
laid upon a wicker plate, and spread flat with a rolling-pin. The bags
and hurdles were then piled in the hydraulic press. There were three
presses, of which the two allotted to the first pressure were charged
alternately, and the third was reserved for a final and more durable
pressure of the _marc_. See PRESS, HYDRAULIC, and STEARINE PRESS.

The juice flowed over the edges of the wicker plates, and fell into the
sill-plate of the press, which was furnished with upright borders, like
a tray, through whose front side a pipe issued, that terminated in a
leathern hose, for conducting the juice into an elevated cistern in the
boiling-house. Here one pound of slaked lime was mixed with every four
hectolitres (about 88 gallons imp.) of juice. The mixture was made to
boil for a little while in a round pan alongside, whence it was decanted
into oblong flat filters, of blanket stuff. The filtered liquor, which
had in general a spec. gravity of 15° Baumé, (about double that of the
fresh juice), was now briskly concentrated by boiling, in an oblong pan,
till it acquired the density of 28° B. The fire being damped with raw
coal, the syrup was run off rapidly by a stopcock into a large basin
with a swing handle, and immediately replaced by fresh defecated liquor.
The basin was carried by two men to the opposite side of the
boiling-house, and emptied into a cistern set on a high platform, whose
horizontal discharge-pipe was provided with a series (five) of
stopcocks, placed respectively over five copper chests (inverted
truncated pyramids), containing a thick bed of granular bone black,
covered with a perforated copper plate. The hot syrup thus filtered had
a pale straw-colour, and was subsequently evaporated in swing pans,
_figs._ 1096, 1097., over a brisk fire, in quantities equivalent to half
a cwt. of sugar, or four hectolitres of average juice.

MAPLE SUGAR.

The manufacture of sugar from the juice of a species of maple tree,
which grow spontaneously in many of the uncultivated parts of North
America, appears to have been first attempted about 1752, by some of the
farmers of New England, as a branch of rural economy.

The sugar maple, the _Acer saccharinum_ of Linnæus, thrives especially
in the states of New York and Pennsylvania, and yields a larger
proportion of sugar than that which grows upon the Ohio. It is found
sometimes in thickets which cover five or six acres of land; but it is
more usually interspersed among other trees. They are supposed to arrive
at perfection in forty years.

The extraction of maple sugar is a great resource to the inhabitants of
districts far removed from the sea; and the process is very simple.
After selecting a spot among surrounding maple trees, a shed is erected,
called the _sugar-camp_, to protect the boilers and the operators from
the vicissitudes of the weather. One or more augers, three-fourths of an
inch in diameter; small troughs for receiving the sap; tubes of elder or
sumach, 8 or 10 inches long, laid open through two-thirds of their
length, and corresponding in size to the auger-bits; pails for emptying
the troughs, and carrying the sap to the camp; boilers capable of
holding 15 or 16 gallons; moulds for receiving the syrup inspissated to
the proper consistence for concreting into a loaf of sugar; and,
lastly, hatchets to cut and cleave the fuel, are the principal utensils
requisite for this manufacture. The whole of February and beginning of
March are the sugar season.

The trees are bored obliquely from below upwards, at 18 or 20 inches
above the ground, with two holes 4 or 5 inches asunder. Care must be
taken that the auger penetrates no more than half an inch into the
alburnum, or white bark; as experience has proved that a greater
discharge of sap takes place at this depth than at any other. It is also
advisable to perforate in the south face of the trunk.

The trough, which contains from two to three gallons, and is made
commonly of white pine, is set on the ground at the foot of each tree,
to receive the sap which flows through the two tubes inserted into the
holes made with the auger; it is collected together daily, and carried
to the camp, where it is poured into casks, out of which the boilers are
supplied. In every case, it ought to be boiled within the course of two
or three days from flowing out of the tree, as it is liable to run
quickly into fermentation, if the weather become mild. The evaporation
is urged by an active fire, with careful skimming during the boiling;
and the pot is continually replenished with more sap, till a large body
has at length assumed a syrupy consistence. It is then allowed to cool,
and passed through a woollen cloth, to free it from impurities.

The syrup is transferred into a boiler to three-fourths of its capacity,
and it is urged with a brisk fire, till it acquires the requisite
consistence for being poured into the moulds or troughs prepared to
receive it. This point is ascertained, as usual, by its exhibiting a
granular aspect, when a few drops are drawn out into a thread between
the finger and the thumb. If in the course of the last boiling, the
liquor froth up considerably, a small bit of butter or fat is thrown
into it. After the molasses have been drained from the concreted loaves,
the sugar is not at all deliquescent, like equally brown sugar from the
cane. Maple sugar is in taste equally agreeable with cane sugar, and it
sweetens as well. When refined, it is equally fair with the loaf sugar
of Europe.

The period during which the trees discharge their juices is limited to
about six weeks. Towards the end of the flow, it is less abundant, less
saccharine, and more difficult to be crystallized.

QUANTITY of SUGAR brought into the Markets of the World, in the year
1838.

                                                        Tons.
  British West Indies                                  160,000
  Mauritius, 35,000; and British East Indies, 20,000    55,000
  Java                                                  36,000
  Manilla and Siam                                      30,000
  Dutch West Indies                                     25,000
  St. Thomas and St. Croix                               7,000
  Martinique and Guadaloupe                             80,000
  Bourbon                                               20,000
  Cuba                                                 100,000
  Brazils                                               95,000
  From Beet-root, in France and Belgium                 65,000
  United States                                         65,000
                                                       -------
                                                       738,000[65]

  [65] For this important table, I am indebted to James Cook, Esq., of
  Mincing-lane.


SUGAR OF LEAD, properly _Acetate of lead_, (_Acetate de plomb_; _Sel de
Saturne_, Fr.; _Essigsaures Bleioxyd_, _Bleizucker_, Germ.) is prepared
by dissolving pure litharge, with heat, in strong vinegar, made of malt,
wood, or wine, till the acid be saturated. A copper boiler, rendered
negatively electrical by soldering a strap of lead within it, is the
best adapted to this process on the great scale. 325 parts of finely
ground and sifted oxide of lead, require 575 parts of strong acetic
acid, of spec. grav. 7° Baumé, for neutralization, and afford 960 parts
of crystallized sugar of lead. The oxide should be gradually sprinkled
into the moderately hot vinegar, with constant stirring, to prevent
adhesion to the bottom; and when the proper quantity is dissolved, the
solution may be weakened with some of the washings of a preceding
process, to dilute the acetate, after which the whole should be heated
to the boiling point, and allowed to cool slowly, in order to settle.
The limpid solution is to be drawn off by a syphon, concentrated by
boiling to the density of 32° B., taking care that there be always a
faint excess of acid, to prevent the possibility of any basic salt being
formed, which would interfere with the formation of regular crystals.
Should the concentrated liquor be coloured, it may be whitened by
filtration through granular bone black.

Stoneware vessels, with salt glaze, answer best for crystallizers. Their
edges should be smeared with candle-grease, to prevent the salt creeping
over them by _efflorescent vegetation_. The crystals are to be drained,
and dried in a stove-room very slightly heated. It deserves remark, that
linen, mats, wood, and paper, imbued with sugar of lead, and strongly
dried, readily take fire, and burn away like tinder. When the
motherwaters cease to afford good crystals, they should be decomposed by
carbonate of soda, or by lime skilfully applied, when a carbonate or an
oxide will be obtained, fit for treating with fresh vinegar. The
supernatant acetate of soda may be employed for the extraction of pure
acetic acid.

A main point in the preparation of sugar of lead, is to use a strong
acid; otherwise much time and acid are wasted in concentrating the
solution. This salt crystallizes in colourless, transparent, four and
six sided prisms, from a moderately concentrated solution; but from a
stronger solution, in small needles, which have a yellow cast if the
acid has been slightly impure. It has no smell, a sweetish astringent
metallic taste, a specific gravity of 2·345; it is permanent in the air
at ordinary temperatures, but effloresces when heated to 95°, with the
loss of its water of crystallization and some acid, falling into a
powder, which passes, in the air, slowly into carbonate of lead. The
crystals dissolve in 1-1/2 times their weight of water at 60°, but in
much less of boiling water, and in 8 parts of alcohol. The solution
feebly reddens litmus paper, but has an alkaline reaction upon the
colours of violets and turmeric. The constituents of the salt are, 58·71
oxide of lead, 27·08 acetic acid, and 14·21 water, in 100.

Acetate of lead is much used in calico-printing. It is poisonous, and
ought to be prepared and handled with attention to this circumstance.

There are two subacetates of lead; the first of which, the
ter-subacetate, has three atoms of base to one of acid, and is the
substance long known by the name of Goulard’s extract. It may be
obtained by digesting with heat a solution of the neutral acetate, upon
pure litharge or massicot. The solution affords white crystalline
scales, which do not taste so sweet as sugar of lead, dissolve in not
less than 30 parts of water, are insoluble in alcohol, and have a
decided alkaline reaction upon test paper. Carbonic acid, transmitted
through the solution, precipitates the excess of the oxide of lead, in
the state of a carbonate, a process long ago prescribed by Thenard for
making white-lead. This subacetate consists of 88·66 of oxide, and 13·34
acid, in 100 parts. It is employed for making the orange sub-chromate of
lead, as also sometimes in surgery.

A _sex-subacetate_, containing six atoms of base, may be obtained by
adding ammonia in excess to a solution of the preceding salt, and
washing the precipitate with dilute water of ammonia. A white powder is
thus formed, that dissolves sparingly in cold water, but gives a
solution in boiling water, from which white silky needles are deposited.
It consists of 92·86 oxide, and 7·14 acid.


SULPHATES, are saline compounds of sulphuric acid with oxidized bases.
The minutest quantity of them present in any solution, may be detected
by the precipitate, insoluble in nitric or muriatic acid, which they
afford with nitrate or muriate of baryta. They are mostly insoluble in
alcohol.


SULPHATE OF ALUMINA AND POTASSA, is alum.


SULPHATE OF AMMONIA, is a salt sometimes formed by saturating the
ammonia liquor of the gas-works with sulphuric acid; and it is employed
for making carbonate of ammonia. See AMMONIA and SAL AMMONIAC.


SULPHATE OF BARYTA, is the mineral called heavy-spar, which frequently
forms the gangue or vein-stone of lead and other metallic ores.


SULPHATE OF COPPER, _Roman or Blue Vitriol_ (_Vitriol de Chypre_, Fr.;
_Kupfervitriol_, Germ.); is a salt composed of sulphuric acid and oxide
of copper, and may be formed by boiling the concentrated acid upon the
metal, in an iron pot. It is, however, a natural product of many copper
mines, from which it flows out in the form of a blue water, being the
result of the infiltration of water over copper pyrites, which has
become oxygenated by long exposure to the air in subterranean
excavations. The liquid is concentrated by heat in copper vessels, then
set aside to crystallize. The salt forms in oblique four-sided tables,
of a fine blue colour; has a spec. gravity of 2·104; an acerb,
disagreeable, metallic taste; and, when swallowed, it causes violent
vomiting. It becomes of a pale dirty blue, and effloresces slightly, on
long exposure to the air; when moderately heated, it loses 36 per cent.
of water, and falls into a white powder. It dissolves in 4 parts of
water, at 60°, and in 2 of boiling water, but not in alcohol; the
solution has an acid reaction upon litmus paper. When strongly ignited,
the acid flies off, and the black oxide of copper remains. The
constituents of crystallized sulphate of copper are--oxide, 31·80; acid,
32·14; and water, 36·06. Its chief employment in this country is in
dyeing, and for preparing certain green pigments. See SCHEELE’S and
SCHWEINFURTH GREEN. In France, the farmers sprinkle a weak solution of
it upon their grains and seeds before sowing them, to prevent their
being attacked by birds and insects.


SULPHATE OF IRON, _Green vitriol_, _Copperas_ (_Couperose verte_, Fr.;
_Eisenvitriol_, _Schwefelsaures Eisenoxydul_, Germ.); is a crystalline
compound of sulphuric acid and protoxide of iron; hence called, by
chemists, the protosulphate; consisting of, 26·10 of base, 29·90 of
acid, and 44·00 of water, in 100 parts; or of 1 prime equivalent of
protoxide, 36, + 1 of acid, 40, + 7 of water, 63, = 139. It may be
prepared by dissolving iron to saturation in dilute sulphuric acid,
evaporating the solution till a pellicle forms upon its surface, and
setting it aside to crystallize. The copperas of commerce is made in a
much cheaper way, by stratifying the pyrites found in the coal measures
(_Vitriolkies_ and _Strahlkies_ of the Germans), upon a sloping puddled
platform of stone, leaving the sulphuret exposed to the weather, till,
by the absorption of oxygen, it effloresces, lixiviating with water the
supersulphate of iron thus formed, saturating the excess of acid with
plates of old iron, then evaporating and crystallizing. The other
pyrites, which occurs often crystallized, called by the Germans
_Schwefelkies_ or _Eisenkies_, must be deprived of a part of its sulphur
by calcination, before it acquires the property of absorbing oxygen from
the atmosphere, and thereby passing from a bisulphuret into a
bisulphate. Alum schist very commonly contains vitriolkies, and affords,
after being roasted and weather-worn, a considerable quantity of
copperas, which must be carefully separated by crystallization from the
alum.

This liquor used formerly to be concentrated directly in leaden vessels;
but the first stage of the operation is now carried on in stone canals
of considerable length, vaulted over with bricks, into which the liquor
is admitted, and subjected at the surface to the action of flame and
heated air, from a furnace of the reverberatory kind, constructed at one
end, and discharging its smoke by a high chimney raised at the other.
See SODA MANUFACTURE. Into this oblong trough, resting on dense clay,
and rendered tight in the joints by water-cement, old iron is mixed with
the liquor, to neutralize the excess of acid generated from the pyrites,
as also to correct the tendency to superoxidizement in copperas, which
would injure the fine green colour of the crystals. After due
concentration and saturation in this surface evaporator, the solution is
run off into leaden boilers, where it is brought to the proper density
for affording regular crystals, which it does by slow cooling, in stone
cisterns.

Copperas forms sea-green, transparent, rhomboidal prisms, which are
without smell, but have an astringent, acerb, inky taste; they speedily
become yellowish-brown in the air, by peroxidizement of the iron, and
effloresce in a warm atmosphere: they dissolve in 1·43 parts of water at
60°, in 0·27 at 190°, and in their own water of crystallization at a
higher heat. This salt is extensively used in dyeing black, especially
hats, in making ink and prussian blue, for reducing indigo in the blue
vat, in the China blue dye, for making the German oil of vitriol, and in
many chemical and medicinal preparations.

There is a persulphate and subpersulphate of iron, but they belong to
the domain of chemistry. The first may be formed, either by dissolving
with heat one part of red oxide of iron (colcothar) in one-and-a-half of
concentrated sulphuric acid, or by adding some nitric acid to a
boiling-hot solution of copperas. It forms with galls and logwood a very
black ink, which is apt to become brown-black. When evaporated to
dryness, it appears as a dirty white pulverulent substance, which is
soluble in alcohol. It consists, in 100 parts, of 39·42 of red oxide of
iron, and 60·58 sulphuric acid.

Hydrated peroxide of iron, prepared by precipitation with alkali from
solution of the persulphate, is an excellent antidote against poisoning
by arsenic. A French _peruquier_, who had swallowed two drams of
arsenious acid, was, after an interval of twenty minutes, treated with
the oxide precipitated from 6 ounces of that salt by caustic potash. It
was diffused in 20 quarts of weak syrup, and administered in successive
doses. After repeated vomiting and purging, the patient felt no more
pain, and was pronounced by the physician to be quite convalescent.

In the copperas and alum works, a very large quantity of ochrey sediment
is obtained; which is a peroxide of iron, containing a little sulphuric
acid and alumina. This deposit, calcined in reverberatory hearths,
becomes of a bright-red colour; and when ground and elutriated, in the
same way as is described under _white lead_, forms a cheap pigment, in
very considerable demand, called _English red_, in the French market.

Colcothar of Vitriol, and Crocus of Mars, are old names for red oxide of
iron. This brown-red powder is obtained in its purest state, by
calcining dried sulphate of iron in a furnace till all its acid be
expelled, and its base become peroxidized. It must be levigated,
elutriated, and dried. This powder is employed extensively in the steel
manufacture, for giving the finishing lustre to fine articles; it is
used by silversmiths under the name of plate powder and _rouge_; and by
the opticians for polishing the specula of reflecting telescopes. Much
of the _crocus_ in the market, is made, however, from the copperas and
alum sediments, and is greatly inferior to the article prepared by the
last process. The finest _rouge_ is made by precipitating the oxide with
soda, then washing and calcining the powder.

An excellent powder for applying to razor-strops, is made by igniting
together in a crucible equal parts of well-dried copperas and sea salt.
The heat must be slowly raised and well regulated, otherwise the
materials will boil over in a pasty state, and the product will be in a
great measure lost. When well made, out of contact of air, it has the
brilliant aspect of plumbago. It has a satiny feel, and is a true _fer
olegiste_, similar in composition to the Elba iron ore. It requires to
be ground and elutriated; after which it affords, on drying, an
impalpable powder, that may be either rubbed on a strop of smooth buff
leather, or mixed up with hog’s-lard or tallow into a stiff cerate.


SULPHATE OF LIME. See GYPSUM.


SULPHATE OF MAGNESIA, _Epsom Salt_ (_Sel amer_, Fr.; _Bittersalz_,
Germ.); exists in sea-water, as also in the waters of Saidschütz,
Sedlitz, and Püllna; and in many saline springs, besides Epsom in
Surrey, whence it has derived its trivial name, and from which it was
first extracted, in the year 1695, and continued to be so, till modern
chemistry pointed out cheaper and more abundant sources of this useful
purgative salt. The sulphate of magnesia, occasionally found effloresced
on the surface of minerals in crystalline filaments, was called
_haarsalz_ (hair salt) by the older writers. The bittern of the Scotch
sea-salt works is muriate of magnesia, mixed, with a little sulphate of
magnesia and chloride of sodium. If the proper decomposing quantity
(found by trial) of sulphate of soda be added to it, and the mixed
solution be evaporated at the temperature of 122° F., chloride of sodium
will form by double affinity, and fall down in cubical crystals; while
the solution of sulphate of magnesia which remains, being evaporated to
the proper point, will afford regular crystals in four-sided prisms with
four-sided acuminations. Or, if bittern be treated in a retort with the
equivalent quantity of sulphuric acid, the muriatic acid may be
distilled off into a series of Woulfe’s bottles, and the sulphate of
magnesia, soda, and lime, will remain in the retort, from which mixture
the sulphate of magnesia may be separated by filtration and
crystallization.

Magnesian limestone being digested with as much muriatic acid as will
dissolve out its lime only, will, after washing, afford, with the
equivalent quantity of sulphuric acid, a pure sulphate of magnesia; and
this is certainly the simplest and most profitable process for
manufacturing this salt upon the great scale. Many prepare it directly,
by digesting upon magnesian limestone the equivalent saturating quantity
of dilute sulphuric acid. The sulphate of lime being separated by
subsidence, the supernatant solution of sulphate of magnesia is
evaporated and crystallized.

This salt is composed of, magnesia 16·72, sulphuric acid 32·39, and
water 50·89. When free from muriate, it tends to effloresce in the air.
It dissolves in 4 parts of water at 32°, in 3 parts at 60°, in 1·4 at
200°, and in its own water of crystallization at a higher heat.


SULPHATE OF MANGANESE, is prepared on the great scale for the
calico-printers, by exposing the peroxide of the metal and pitcoal
ground together, and made into a paste with sulphuric acid, to a heat of
400° F. On lixiviating the calcined mass, a solution of the salt is
obtained, which is to be evaporated and crystallized. It forms pale
amethyst-coloured prisms, which have an astringent bitter taste,
dissolve in 2-1/2 parts of water, and consist of, protoxide of manganese
31·93, sulphuric acid 35·87, and water 32·20, in 100 parts.


SULPHATE OF MERCURY, is a white salt which is used in making corrosive
sublimate. See MERCURY. The subsulphate, called _Turbith Mineral_, is a
pale yellow pigment, and may be prepared by washing the white sulphated
peroxide with hot water, which resolves it into the soluble
supersulphate, and the insoluble subsulphate, or _Turbith_. It is
poisonous.


SULPHATE OF POTASSA, is obtained by first igniting and then
crystallizing the residuum of the distillation of nitric acid from
nitre.


SULPHATE OF SODA, is commonly called Glauber’s salt, from the name of
the chemist who first prepared it. It is obtained by igniting and then
crystallizing the residuum of the distillation of muriatic acid from
common salt. It crystallizes in channelled 6-sided prisms. See SODA
MANUFACTURE.


SULPHATE OF ZINC, called also _White Vitriol_, is commonly prepared in
the Harz, by washing the calcined and effloresced sulphuret of zinc or
blende, on the same principle as green and blue vitriol are obtained
from the sulphurets of iron and copper. Pure sulphate of zinc may be
made most readily by dissolving the metal in dilute sulphuric acid,
evaporating and crystallizing the solution. It forms prismatic crystals,
which have an astringent, disagreeable, metallic taste; they effloresce
in a dry air, dissolve in 2·3 parts of water at 60°, and consist
of--oxide of zinc, 28·29; acid, 28·18; water, 43·53. Sulphate of zinc is
used for preparing drying oils for varnishes, and in the reserve or
resist pastes of the calico-printer.


SULPHITES, are a class of salts, consisting of sulphurous acid, combined
in equivalent proportions with the oxidized bases.


SULPHOSELS, is the name given by Berzelius to a class of salts which may
be prepared as follows:--1. Dissolve a salt consisting of an oxide and
an acid (an _oxisalt_), in a very small quantity of water, and pass
through the solution a stream of sulphuretted hydrogen, till the salt be
entirely decomposed. In this operation, the _oxisalt_ is transformed
into a _sulphosalt_, by the sulphur of the compound gas; while its
hydrogen forms water with the oxygen of the saline base. This process is
applicable only to the metallic salts; and among these, not to the
nitrates, carbonates, or phosphates. 2. Another method of preparing
_sulphosalts_ is, to add to a watery solution of sulphuret of
potassium, an electro-negative metallic sulphuret, which will dissolve
in the liquid till the sulphuret of potassium be saturated. This saline
compound is to be employed to effect double decompositions with the
oxisalts; that is, to convert the radical of another base, combined with
an _oxacid_, into a sulphosalt. 3. If the electro-negative sulphuret be
put in powder into a solution of the hydrosulphuret of potassa, it will
dissolve and expel the sulphuretted hydrogen with effervescence; just as
carbonic acid is displaced by a stronger acid. For his other three
methods of preparing _sulphosalts_, see his _Elements_, vol. iii. p.
336, Fr. translation.


SULPHUR; _Brimstone_ (_Soufre_, Fr.; _Schwefel_, Germ.); is a simple
combustible, solid, non-metallic, of a peculiar yellow colour, very
brittle, melting at the temperature of 226° Fahr., and possessing, after
it has been fused, a specific gravity of 1·99. When held in a warm hand,
a roll of sulphur emits a crackling sound, by the fracture of its
interior parts; and when it is rubbed, it emits a peculiar well-known
smell, and acquires at the same time negative electricity. When heated
to the temperature of 560° F. it takes fire, burns away with a dull blue
flame of a suffocating odour, and leaves no residuum. When more strongly
heated, sulphur burns with a vivid white flame. It is not affected by
air or water.

Sulphur is an abundant product of nature; existing sometimes pure or
merely mixed, and at others in intimate chemical combination with
oxygen, and various metals, forming sulphates and sulphurets. See Ores
of COPPER, IRON, LEAD, &c., under these metals.

[Illustration: 1100]

_Fig._ 1100. represents one of the cast-iron retorts used at Marseilles
for refining sulphur, wherein it is melted and converted into vapours,
which are led into a large chamber for condensation. The body _a_, of
the retort is an iron pot, 3 feet in diameter outside, 22 inches deep,
half an inch thick, which weighs 14 cwt., and receives a charge of 8
cwt. of crude sulphur. The grate is 8 inches under its bottom, whence
the flame rises and plays round its sides. A cast-iron capital _b_,
being luted to the pot, and covered with sand, the opening in front is
shut with an iron plate. The chamber _d_, is 23 feet long, 11 feet wide,
and 13 feet high, with walls 32 inches thick. In the roof, at each
gable, valves or flap-doors, _e_, 10 inches square, are placed at the
bottom of the chimney _c_. The cords for opening the valves are led down
to the side of the furnace. The entrance to the chamber is shut with an
iron door. In the wall opposite to the retorts, there are two apertures
near the floor, for taking out the sulphur. Each of the two retorts
belonging to a chamber is charged with 7-1/2 or 8 cwts. of sulphur; but
one is fired first, and with a gentle heat, lest the brimstone froth
should overflow; but when the fumes begin to rise copiously, with a
stronger flame. The distillation commences within an hour of kindling
the fire, and is completed in six hours. Three hours after putting fire
to the first retort, the second is in like manner set in operation.

When the process of distillation is resumed, after having been some time
suspended, explosions may be apprehended, from the presence of
atmospherical air; to obviate the danger of which, the flap-doors must
be opened every 10 minutes; but they should remain closed during the
setting of the retorts, and the reflux of sulphurous fumes or acid
should be carried off by a draught-hood over the retorts. The
distillation is carried on without interruption during the week, the
charges being repeated four times in the day. By the third day, the
chamber acquires such a degree of heat as to preserve the sulphur in a
liquid state; on the sixth, its temperature becoming nearly 300° F.,
gives the sulphur a dark hue, on which account the furnace is allowed to
cool on the Sunday. The fittest distilling temperature is about 248°.
The sulphur is drawn off through two iron pipes cast in the iron doors
of the orifices on the side of the chamber opposite to the furnace. The
iron stoppers being taken out of the mouths of the pipes, the sulphur is
allowed to run along an iron spout placed over red-hot charcoal, into
the appropriate wooden moulds.

_Native sulphur_ in its pure state is solid, brittle, transparent,
yellow, or yellow bordering on green, and of a glassy lustre when newly
broken. It occurs frequently in crystalline masses, and sometimes in
complete and regular crystals, which are all derivable from the
rhomboidal octahedron. The fracture is usually conchoidal and shining.
Its specific gravity is 2·072, exceeding somewhat the density of melted
sulphur. It possesses a very considerable refractive power; and doubles
the images of objects even across two parallel faces. Sulphur,
crystallized by artificial means, presents a very remarkable phenomenon;
for by varying the processes, crystals are obtained whose forms belong
to two different systems of crystallization. The red tint, so common in
the crystals of Sicily, and of volcanic districts, has been ascribed by
some mineralogists to the presence of realgar, and by others to iron;
but Stromeyer has found the sublimed orange-red sulphur of Vulcano, one
of the Lipari islands, to result from a natural combination of sulphur
and selenium.

It is extracted from the minerals containing it, at Solfatara, by the
following process:--

Ten earthen pots, of about a yard in height, and 4-1/2 gallons imperial
in capacity, bulging in the middle, are ranged in a furnace called a
gallery; five being set on the one side, and five on the other. These
are so distributed in the body of the walls of the gallery, that their
belly projects partly without, and partly within, while their top rises
out of the vault of the roof. The pots are filled with lumps of the
sulphur ore of the size of the fist; their tops are closed with
earthenware lids, and from their shoulder proceeds a pipe of about 2
inches diameter, which bends down, and enters into another covered pot,
with a hole in its bottom, standing over a tub filled with water. On
applying heat to the gallery, the sulphur melts, volatilizes, and runs
down in a liquid state into the tubs, where it congeals. When one
operation is finished, the pots are re-charged, and the process is
repeated.

In Saxony and Bohemia, the sulphurets of iron and copper are introduced
into large earthenware pipes, which traverse a furnace-gallery; and the
sulphur exhaled flows into pipes filled with cold water, on the outside
of the furnace. 900 parts of sulphuret afford from 100 to 150 of
sulphur, and a residuum of metallic protosulphuret. See METALLURGY and
COPPER.

Volcanic sulphur is purer than that extracted from pyrites; and as the
latter is commonly mixed with arsenic, and some other metallic
impregnations, sulphuric acid made of it would not answer for many
purposes of the arts; though a tolerably good sulphuric acid may be made
directly from the combustion of pyrites, instead of sulphur, in the lead
chambers. The present high price of the Sicilian sulphur is a great
encouragement to its extraction from pyrites. It is said that the common
English brimstone, such as was extracted from the copper pyrites of the
Parys mine of Anglesey, contained fully a fifteenth of residuum,
insoluble in boiling oil of turpentine, which was chiefly orpiment;
while the fine Sicilian sulphur, now imported in vast quantities by the
manufacturers of oil of vitriol, contains not more than 3 per cent. of
foreign matter, chiefly earthy, but not at all arsenical.

Sulphur has been known from the most remote antiquity. From its kindling
at a moderate temperature, it is employed for readily procuring fire,
and lighting by its flame other bodies not so combustible. At Paris, the
preparation of sulphur matches constitutes a considerable branch of
industry. The sulphurous acid formed by the combustion of sulphur in the
atmospheric air, is employed to bleach woollen and silken goods, as also
cotton stockings; to disinfect vitiated air, though it is inferior in
power to nitric acid vapour and chlorine; to kill mites, moths, and
other destructive insects in collections of zoology; and to counteract
too rapid fermentation in wine-vats, &c. As the same acid gas has the
property of suddenly extinguishing flame, sulphur has been thrown into a
chimney on fire, with the best effect; a handful of it being sometimes
sufficient. Sulphur is also employed for cementing iron bars in stone;
for taking impressions from seals and cameos, for which purpose it is
kept previously melted for some time, to give the casts an appearance of
bronze. Its principal uses, however, are for the manufactures of
vermillion, or cinnabar, gunpowder, and sulphuric acid.

See METALLURGY, page 823, for the description of Gahn’s furnace for
extracting sulphur from pyrites.

Pyrites as a bi-sulphuret, consisting of 45·5 parts of iron, and 54·5 of
sulphur, may, by proper chemical means, be made to give off one half of
its sulphur, or about 27 per cent.; but great care must be taken not to
generate sulphurous acid, as is done very wastefully by the Fahlun and
the Goslar processes. By the latter, indeed, not more than 1 or 2 parts
of sulphur are obtained, by roasting 100 parts of the pyritous ores of
the Rammelsberg mines. In these cases, the sulphur is burned, instead of
being sublimed. The residuum of the operation, when it is well
conducted, is black sulphuret of iron, which may be profitably employed
for making copperas. The apparatus for extracting sulphur from pyrites
should admit no more air than is barely necessary to promote the
sublimation.--Sicily produced last year 70,000 tons of sulphur, and
Tuscany 1200; of which Great Britain consumed 46,000; France, 18,000;
other places, 6000. In 1820, Great Britain consumed only 5000 tons.


SULPHURATION, is the process by which woollen, silk, and cotton goods
are exposed to the vapours of burning sulphur, or to sulphurous acid
gas. In the article STRAW-HAT MANUFACTURE, I have described a simple and
cheap apparatus, well adapted to this operation.

Sulphuring-rooms are sometimes constructed upon a great scale, in which
blankets, shawls, and woollen clothes may be suspended freely upon poles
or cords. The floor should be flagged with a sloping pavement, to favour
the drainage of the water that drops down from the moistened cloth. The
iron or stoneware vessels, in which the sulphur is burned, are set in
the corners of the apartment. They should be increased in number
according to the dimensions of the place, and distributed uniformly over
it. The windows and the entrance door must be made to shut hermetically
close. In the lower part of the door, there should be a small opening,
with a sliding shutter, which may be raised or lowered by the mechanism
of a cord passing over a pulley.

The aperture by which the sulphurous acid and azotic gases are let off,
in order to carry on the combustion, should be somewhat larger than the
opening at the bottom. A lofty chimney carries the noxious gases above
the building, and diffuses them over a wide space, their ascension being
promoted by means of a draught-pipe of iron, connected with an ordinary
stove, provided with a valve to close its orifice when not kindled.

When the chamber is to be used, the goods are hung up, and a small fire
is made in the draught-stove. The proper quantity of sulphur being next
put into the shallow pans, it is kindled, the entrance door is closed,
as well as its shutter, while a vent-hole near the ground is opened by
drawing its cord, which passes over a pulley. After a few minutes, when
the sulphur is fully kindled, that vent-hole must be almost entirely
shut, by relaxing the cord; when the whole apparatus is to be let alone
for a sufficient time.

The object of the preceding precautions is to prevent the sulphurous
acid gas escaping from the chamber by the seams of the principal
doorway. This is secured by closing it imperfectly, so that it may admit
of the passage of somewhat more air than can enter by the upper seams,
and the smallest quantity of fresh air that can support the combustion.
The velocity of the current of air may be increased at pleasure, by
enlarging the under vent-hole a little, and quickening the fire of the
draught-stove.

Before opening the entrance door of the apartment, for the discharge of
the goods, a small fire must be lighted in the draught furnace, the
vent-hole must be thrown entirely open, and the sliding shutter of the
door must be slid up, gradually more and more every quarter of an hour,
and finally left wide open for a proper time. By this means the air of
the chamber will become soon respirable.


SULPHURETTED HYDROGEN, is a gas, composed of one part of hydrogen and
sixteen parts of sulphur, by weight. Its specific gravity is 1·1912,
compared to air = 1·0000. It is the active constituent of the
sulphureous mineral waters. When breathed, it is very deleterious to
animal life; and being nearly twice as dense as air, it may be poured
from its generating bottle into cavities; a scheme successfully employed
by M. Thenard to destroy rats in their holes.


SULPHURIC ACID, _Vitriolic Acid_, or _Oil of Vitriol_ (_Acid
sulfurique_, Fr.; _Schwefelsaüre_, Germ.). This important product, the
agent of many chemical operations, was formerly procured by the
distillation of dried sulphate of iron, called _green_ vitriol, whence
the corrosive liquid which came over, having an oily consistence, was
denominated oil of vitriol. This method has been superseded in Great
Britain, France, and most other countries, by the combustion of sulphur
along with nitre, in large leaden chambers; but as the former process,
which is still practised at Bleyl in Bohemia, and Nordhausen in Saxony,
gives birth to some interesting results, I shall describe it briefly.

Into a long horizontal furnace, or gallery of brickwork, a series of
earthenware retorts, of a pear shape, is arranged, with curved necks
fitted into stoneware bottles or condensers. Each retort is charged with
sulphate of iron, which has been previously heated to moderate redness.
The first product of the distillation, a slightly acidulous phlegm, is
allowed to escape; then the retort and receiver are securely luted
together. The fire is now raised, and urged briskly for 36 hours,
whereby the strong sulphuric acid is expelled, in the form of heavy
white vapours, which condense in the cold receiver into an oily-looking
liquid. The latter portions, when received in a separate refrigerator,
frequently concrete into a crystalline mass, formerly called glacial oil
of vitriol. About 64 pounds of strong acid may be obtained from 600
pounds of copperas. It is brown-coloured; and varies in specific-gravity
from 1·842 to 1·896. Its boiling point is so low as 120° Fahr. When
re-distilled in a glass retort, into a receiver surrounded with ice, a
very moderate heat sends over white fumes, which condense into a soft
solid, in silky filaments, like asbestos, tough, and difficult to cut.
When this is exposed to the air, it emits copious fumes of sulphuric
(not sulphurous) acid. It burns holes in paper as rapidly as a red-hot
iron. Dropped in small quantities into water, it excites a hissing
noise, like ignited metal; and in larger quantities, it occasions an
explosion. By dropping a fragment of it into a poised phial containing
water, and stoppering instantly, to prevent the ejection of liquid, by
the ebullition which always ensues, I got a dilute acid, containing a
known portion of the solid acid, from the specific gravity of which, as
well as from its saturating power, I ascertained that the above solid
sulphuric acid was truly anhydrous (_void of water_), consisting of 1
equivalent proportion of sulphur, and 3 of oxygen; or, by weight, of 16
of the former, and 24 of the latter. This acid makes a red solution of
indigo.

The production of sulphuric acid from sulphur and nitre may be elegantly
illustrated by means of a glass globe with a stoppered hole at its side,
and four bent glass tubes inserted into a leaden cap in its upper
orifice. The first tube is to be connected with a heated matrass,
disengaging sulphurous acid from copper filings and sulphuric acid; the
second with a retort, disengaging more slowly deutoxide of azote (nitric
oxide) from copper filings and nitric acid; the third with a vessel for
furnishing steam in a moderate current towards the end of the process,
when no water has been previously admitted into the balloon; the fourth
tube may be upright, and terminate in a small funnel. Through the
opening in the side of the globe, atmospherical air is to be admitted
from time to time, by removing the stopper; after which, the residuary
lighter azote may be allowed to escape by the funnel orifice.

The nitric oxide first absorbs oxygen from the air, becomes, in
consequence, nitrous acid vapour, which giving up one third of its
oxygen to the sulphurous acid, converts this, with the aid of water,
into sulphuric acid, while itself returning to the state of nitric
oxide, is again qualified to take oxygen from the air, and to transfer
it to the sulphurous acid gas; and thus in perpetual rotation. These
oxygenating and disoxygenating processes continue until nearly the whole
oxygen of the atmospheric air contained in the globe is consumed. Were
there little aqueous vapour present, those gases would soon cease to
operate upon each other; for though the nitric oxide became nitrous
acid, this would oxygenate little of the sulphurous acid, because the
three substances would condense into white crystals upon the sides of
the balloon, like hoar frost upon a window-pane in winter. These
indicate a deficiency of aqueous vapour, and an excess of nitrous acid.
On the admission of steam, the crystals disappear, the sulphuric acid is
liquefied, the nitrous acid is converted into nitric acid and nitric
oxide; the former of which combines with the water, while the latter is
converted by the atmospheric oxygen into nitrous acid vapour. A certain
quantity of water is therefore requisite to prevent the formation of
that crystalline compound, which condenses the nitrous acid, and renders
it inoperative in transforming fresh portions of sulphurous acid into
sulphuric. On these principles alone is it possible to oxygenate the
sulphurous acid, by the nitrous acid resuming and surrendering a dose of
oxygen, in perpetual alternation.

It was MM. Clement and Desormes who first had the sagacity to trace
these complicated changes. They showed that nitrous acid gas and
sulphurous acid gas mixed, react on each other through the intervention
of moisture; that there resulted thence a combination of sulphuric acid,
deutoxide of azote (nitrous gas), and water; that this crystalline
compound was instantly destroyed by more water, with the separation of
the sulphuric acid in a liquid state, and the disengagement of nitrous
gas; that this gas re-constituted nitrous acid at the expense of the
atmospheric oxygen of the leaden chamber, and thus brought matters to
their primary condition. From this point, starting again, the particles
of sulphur in the sulphurous acid, through the agency of water, became
fully oxygenated by the nitrous acid, and fell down in heavy drops of
sulphuric acid, while the nitrous gas derived from the nitrous acid, had
again recourse to the air for its lost dose of oxygen. This beautiful
interchange of the oxygenous principle was found to go on, in their
experiments, till either the sulphurous acid, or oxygen in the air, was
exhausted.

They verified this proposition, with regard to what occurs in sulphuric
acid chambers, by mixing in a crystal globe the three substances,
deutoxide of azote, sulphurous acid, and atmospheric air. The immediate
production of red vapours indicated the transformation of the deutoxide
into nitrous acid gas; and now the introduction of a very little water
caused the proper _reaction_, for opaque vapours rose, which deposited
white star-form crystals on the surface of the glass. The gases were
once more transparent and colourless; but another addition of water
melted these crystals with effervescence, when ruddy vapours appeared.
In this manner the phenomena were made to alternate, till the oxygen of
the included air was expended, or all the sulphurous acid was converted
into sulphuric. The residuary gases were found to be nitrous acid gas,
and azote, without sulphurous acid gas; while unctuous sulphuric acid
bedewed the inner surface of the globe. Hence, they justly concluded
their new theory of the manufacture of oil of vitriol to be
demonstrated.

In consequence of their discovery, the manufacture of this acid has
received such improvements, that a nearly double product of it may now
be obtained from the same weight of materials. Indeed, the economy may
be reckoned to be much greater; for one half of the more costly
ingredient, the nitre, formerly employed with a given weight of sulphur,
suffices at present.

In the manufacture of sulphuric acid upon the great scale, two different
systems of working were long prevalent; the intermittent or periodical,
and the continuous or uniform. Both were carried on in large leaden
chambers. In the former, the chambers were closed during the period of
combustion and gaseous combination, but were opened from time to time to
introduce fresh atmospheric air. This method is, I believe, generally
abandoned now, on account of the difficulties and delays attending it,
though it afforded large products in skilful hands. In the latter, a
continuous current of air is allowed to enter at the oven in front of
the chamber for the combustion of the sulphur, and there is a constant
escape of nitrogen gas, with a little sulphurous acid gas, at the remote
end of the roof.

[Illustration: 1101]

_Fig._ 1101. represents a sulphuric acid chamber, _a_, _a_, are the
brick or stone pillars upon which it rests; _b_, _b_, are the sustaining
wooden beams or joists; _c_, is the chimney for the discharge of the
nitrogen; _d_, is the roof, and _e_, the sole of the hearth for the
combustion of the sulphur; _f_, is the cylindrical tunnel, or pipe of
lead or cast iron, for conducting the gasiform materials into the
chamber; _g_, is the steam-boiler; and _h_, the steam-pipe. That plan is
variously modified, by different oil-of-vitriol makers in this country
and in France. Very frequently, the oven _e_, _d_, is not situated under
the chamber, but is built at the end of it, as at _i_, and arched over
with brick, the crown being 9 inches thick. The pipe _f_, 18 inches in
diameter, is then placed outside of the chamber, being inserted into a
brick chimney, and, turning rectangularly, enters it opposite _k_. The
sole of the hearth _e_, is a thick plate of cast iron (not hollowed as
shown in the figure), 5 or 6 feet long, and 3 or 4 broad, with a small
fireplace constructed beneath it, whose smoke-flue runs outwards, under
the floor, to the side wall of the building. The oven is in this case
about 2 feet in height, from the sole to the roof; and it has an iron
door, about 12 inches by 15, which slides up and down in a
tightly-fitted iron frame. This door is frequently placed in the side of
the oven, parallel to the long side of the leaden chamber. A stout
collar of lead is bolted to the chamber, where the pipe enters it. At
the middle of the side of the chamber, about 2 feet above the ground, a
leaden trough is fixed, which serves as a syphon-funnel and water-trap
for introducing water to the acid gases.

Several manufacturers divide the chamber into a series of rectangular
compartments, by parallel leaden screens, 10 or 12 feet asunder, and
allow these compartments to communicate by a narrow opening, or a hole 1
foot square, in the top and bottom of each screen alternately. Thus the
fumes, which enter from the chimney-pipe over _k_, will be forced, by
the screen at _b_, to descend to 1, and pass through the opening there,
to get into the second compartment, whence they will escape near the top
at 2, thus circulating up and down, so as to occasion a complete
agitation and intermixture of their heterogeneous particles. Into the
side of the chamber, opposite to the centre of each compartment, a lead
pipe enters, and proceeds towards the middle of the area, terminating in
a narrow orifice, for discharging a jet of high-pressure steam from a
boiler loaded with 40 pounds upon the square inch. This boiler should be
placed under a shed exterior to the building. It deserves to be noted,
that the incessant tremors produced in this pipe by the escape of the
steam, cause the orifice to contract, and eventually to close almost
entirely, just as the point of a glass tube does when exposed directly
to the flame of a blowpipe. Provision should therefore be made against
this event, by the chemical engineer.

Equidistant between the middle point and each end of the chamber, two
round holes are cut out in its side, about 16 inches in diameter, and 2
feet from the floor; the sheet lead being folded back over the face of
the strong deals which strengthen the chamber in that place. The edges
of the holes are bevelled outwards, so as to fit a large conical plug of
wood faced with lead, called a man-hole door. One or other of these
doors is opened from time to time, to allow the superintendent to
inspect the process, or workmen to enter, after the chamber is well
ventilated, for the purpose of making repairs. The joists or tie-beams,
that bind the rafters of the roof of both the leaden chamber and the
house, must be at least 7 inches deep, by 3 broad, and of such length as
to have their ends supported upon the outer wall, or the columnar
supports of the roof, in case a number of chambers are enclosed together
in parallel ranges under a vast shed. These beams, which lie two feet
apart, suspend the leaden roof, by means of leaden straps, soldered to
its upper surface and edges. The sides of the chamber are sustained by
means of similar leaden straps affixed to the wooden posts (uprights), 4
inches broad by 3 thick, placed two or three feet apart along the sides
of the chamber; resting on the ground below, and mortised into the
tie-beams above. Some chambers rest upon a sand-floor; but they are
preferably placed upon wooden joists, supported by pillars stretching
over an open area, as shown in the figure, into which the workmen may
descend readily, to examine the bottom.

The outlet _c_, on the top of the chamber, is sometimes joined to a long
pipe of lead laid nearly horizontally, with a slight inclination
upwards, along the roof, for favouring the condensation and return of
acid matter.

At the extremity _l_, of the chamber, which, having a downward slope of
1 inch in every 20 feet, should stand from 3 to 6 inches (according to
its length) lower than _i_, one leg of an inverted syphon pipe is fixed
by fusion, into which the liquid of the chamber passing, will show by
its altitude the depth on the bottom within. From the cup-shaped orifice
of that bent-up pipe, the acid of the chamber is drawn off by an
ordinary leaden syphon into the concentration pans.

The sheet lead of which the sides and top are made, should weigh from 5
to 6 pounds per square foot; that of the bottom should be nearly of
double thickness.

Having now detailed, with sufficient minuteness, the construction of the
chamber, I shall next describe the mode of operating with it. There are
at least two plans at present in use for burning the sulphur
continuously in the oven. In the one, the sulphur is laid on the hearth
_e_, (or rather on the flat hearth in the separate oven, above
described,) and is kindled by a slight fire placed under it; which fire,
however, is allowed to go out after the first day, because the oven
becomes by that time sufficiently heated by the sulphur flames to carry
on the subsequent combustion. Upon the hearth, an iron tripod is set,
supporting, a few inches above it, a hemispherical cast-iron bowl
(basin) charged with nitre and its decomposing proportion of strong
sulphuric acid. In the other plan, 12 parts of bruised sulphur, and 1 of
nitre, are mixed in a leaden trough on the floor with 1 of strong
sulphuric acid, and the mixture is shovelled through the sliding iron
door upon the hot hearth. The successive charges of sulphur are
proportioned, of course, to the size of the chamber. In one of the
largest, which is 120 feet long, 20 broad, and 16 high, 12 cwt. are
burned in the course of 24 hours, divided into 6 charges, every fourth
hour, of 2 cwt. each. In chambers of one-sixth greater capacity,
containing 1400 metres cube, 1 ton of sulphur is burned in 24 hours.
This immense production was first introduced at Chaunay and Dieuze,
under the management of M. Clement-Desormes. The bottom of the chamber
should be covered at first with a thin stratum of sulphuric acid, of
spec. grav. 1·07, which decomposes nitrous acid into oxygen and nitrous
gas; but not with mere water, which would absorb the nitrous acid
vapours, and withdraw them from their aerial sphere of action. The
vapour of nitric acid, disengaged from the nitre on the hearth of the
oven, when brought into intimate contact with the sulphurous acid,
either gives up oxygen to it, becomes itself nitrous gas, and converts
it into sulphuric acid; or combines with the sulphurous acid into the
crystalline compound above described, which, the moment it meets with
moisture, is decomposed into sulphuric acid and nitrous gas. The
atmospherical oxygen of the chamber immediately reconverts this gas into
nitrous or nitric acid fumes, which are again ready, with the
co-operation of sulphurous acid gas and aqueous vapour, to produce fresh
quantities of hydrous sulphuric acid (oil of vitriol) and nitrous gas.
At low temperatures, this curious play of chemical affinities has a
great tendency to form the crystalline compound, and to deposit it in a
crust of considerable thickness (from one-half to one inch) on the sides
of the chamber, so as to render the process inoperative. A circumstance
of this kind occurred, in a very striking manner, during winter, in a
manufacture of oil of vitriol in Russia; and it has sometimes occurred,
to a moderate extent, in Scotland. It is called, at Marseilles, the
_maladie des chambres_. It may be certainly prevented, by maintaining
the interior of the chamber, by a jet of steam, at a temperature of 100°
F. When these crystals fall into the dilute acid at the bottom, they are
decomposed with a violent effervescence, and a hissing gurgling noise,
somewhat like that of a tun of beer in brisk fermentation.

M. Clement-Desormes demonstrated the proposition relative to the
influence of temperature by a decisive experiment. He took a glass
globe, furnished with three tubulures, and put a bit of ice into it.
Through the first opening he then introduced sulphurous acid gas;
through the second, oxygen; and through the third, nitrous gas
(deutoxide of azote). While the globe was kept cool, by being plunged in
iced water, no sulphuric acid was formed, though all the ingredients
essential to its production were present. But on exposing the globe to a
temperature of 100° Fahr., the four bodies began immediately to react on
each other, and oil of vitriol was condensed in visible _striæ_.

The introduction of steam is a modern invention, which has vastly
facilitated and increased the production of oil of vitriol. It serves,
by powerful agitation, not only to mix the different gaseous molecules
intimately together, but to impel them against each other, and thus
bring them within the sphere of their mutual chemical attraction. This
is its mechanical effect. Its chemical agency is still more important.
By supplying moisture at every point of the immense included space, it
determines the formation of hydrous sulphuric acid, from the compound of
nitric, nitrous, sulphurous, and dry sulphuric acids. No sooner is this
reaction accomplished, than the nitrous gas resumes its oxygen, from the
continuous atmospherical current, and becomes again fit to operate a
like round of transmutations with sulphurous acid, steam, and oxygen.
The nitrogen (azote), which ought to be the only residuum in a
_perfectly_ regulated vitriol chamber, escapes, by its relative
lightness, at the opening _c_, in the roof, or, more properly speaking,
is displaced by the influx of the heavier gases at the entrance-pipe.

On the intermittent plan, after the consumption of each charge, and
condensation of the product, the chamber was opened, and freely
ventilated, so as to expel the residuary azote, and replenish it with
fresh atmospheric air. In this system there were four distinct stages or
periods:--1. Combustion for two hours; 2. Admission of steam, and
settling, for an hour and a half; 3. Conversion, for three hours, during
which interval the drops of strong acid were heard falling like heavy
hailstones on the bottom; 4. Purging of the chamber, for three quarters
of an hour.

By the continuous method, sulphuric acid may be currently obtained in
the chambers, of the specific gravity 1·350, or 1·450 at most; for, when
stronger, it absorbs and retains permanently much nitrous acid gas; but
by the intermittent, so dense as 1·550, or even 1·620; whence in a
district where fuel is high priced, as near Paris, this method
recommended itself by economy in the concentration of the acid. In Great
Britain, and even in most parts of France, however, where time,
workmen’s wages, and interest of capital, are the paramount
considerations, manufacturers do not find it for their interest in
general to raise the density of the acid in the chambers above 1·400, or
at most 1·500; as the further increase goes on at a retarded rate, and
its concentration from 1·400 to 1·600, in leaden pans, costs very
little.

At about the specific gravity of 1·35, in Great Britain, the liquid of
the chambers is run off, by the syphon above described, into a leaden
gutter or spout, which discharges it into a series of rectangular
vessels made of large sheets of lead, of 12 or 14 lbs. to the square
foot, simply folded up at the angles into pans 8 or 10 inches deep,
resting upon a grate made of a pretty close row of wrought-iron bars of
considerable strength, under which the flame of a furnace plays. Where
coals are very cheap, each pan may have a separate fire; but where they
are somewhat dear, the flame, after passing under the lowest pan of the
range, which contains the strongest acid (at about 1·600), proceeds
upwards with a slight slope to heat the pans of weaker acid, which, as
it concentrates, is gradually run down by syphons to replenish the lower
pans, in proportion as their aqueous matter is dissipated. The 3 or 4
pans constituting the range are thus placed in a straight line, but each
at a different level, terrace-like; _en gradins_, as the French say.

When the acid has thereby acquired the density of 1·650, or 1·700 at
most, it must be removed from the leaden evaporators, because, when of
greater strength, it would begin to corrode them; and it is transferred
into leaden coolers, or run through a long refrigeratory worm-pipe
surrounded by cold water. In this state it is introduced into glass or
platinum retorts, to undergo a final concentration, up to the specific
gravity of 1·842, or even occasionally 1·845, in consequence of slight
saline impurities. When glass retorts are used, they are set in a long
sand-bath over a gallery furnace, resting on fire tiles, under which a
powerful flame plays; and as the flue gradually ascends from the
fireplace, near to which it is most distant from the tiles; to the
remoter end, the heat acts with tolerable equality on the first and last
retort in the range. When platinum stills are employed, they are fitted
into the inside of cast-iron pots, which protect the thin bottom and
sides of the precious metal. The fire being applied directly to the
iron, causes a safe, rapid, and economical concentration of the acid.
The iron pots, with their platinum interior, filled with concentrated
boiling-hot oil of vitriol, are lifted out of the fire-seat by tackle,
and let down into a cistern of cold water, to effect the speedy
refrigeration of the acid, and facilitate its transvasion into carboys
packed in osier baskets lined with straw. Sometimes, however, the acid
is cooled by running it slowly off through a long platinum syphon,
surrounded by another pipe filled with cold water. _Fig._ 1102. shows my
contrivance for this purpose.

[Illustration: 1102]

The under stopcock _a_, being shut, and the leg _b_, being plunged to
nearly the bottom of the still, the worm is to be filled with
concentrated cold acid through the funnel _c_. If that stopcock is now
shut, and _a_ opened, the acid will flow out in such quantity as to
rarefy the small portion of air in the upper part of the pipe _b_,
sufficiently to make the hot acid rise up over the bend, and set the
syphon in action. The flow of the fluid is to be so regulated by the
stopcock _a_, that it may be greatly cooled in its passage by the
surrounding cold water in the vessel _f_, which may be replenished by
means of the tube and funnel _d_, and overflow at _e_.

A manufacturer of acid in Scotland, who burns in each chamber 210 pounds
of sulphur in 24 hours, being at the rate of 420 pounds for 20,000 cubic
feet (= nearly 2000 metres cube) has a product of nearly 3 pounds of
concentrated oil of vitriol for every pound of sulphur and twelfth of a
pound of nitre. The advantage of his process results, I conceive, from
the lower concentration of the acid in the chambers, which favours its
more rapid production.

The platinum retort admits of from 4 to 6 operations in a day, when it
is well mounted and managed. It has a capital of platinum, furnished
with a short neck, which conducts the disengaged vapours into a lead
worm of condensation; and the liquid thus obtained is returned into the
lead pans. Great care must be taken to prevent any particles of lead
from getting into the platinum vessel, since at the temperature of
boiling sulphuric acid, the lead unites with the precious metal, and
thus causes holes in the retort. These must be repaired by soldering-on
a plate of platinum with gold.

Before the separate oven or hearth for burning the sulphur in contact
with the nitre was adopted, this combustible mixture was introduced into
the chamber itself, spread on iron trays or earthen pans, supported
above the water on iron stands. But this plan was very laborious and
unproductive. It is no longer followed.

One of the characters of the good quality of sulphuric acid, is its
dissolving indigo without altering its fine blue colour.

Sulphuric acid, when well prepared, is a colourless and inodorous
liquid, of an oily aspect, possessing a specific gravity, in its most
concentrated state, of 1·842, when redistilled, but as found in
commerce, of 1·845. It is eminently acid and corrosive, so that a single
drop will communicate the power of reddening litmus to a gallon of
water, and will produce an ulcer of the skin when allowed to remain upon
it. If swallowed in its strongest state, in even a small quantity, it
acts so furiously on the throat and stomach as to cause intolerable
agony and speedy death. Watery diluents, mixed with chalk or magnesia,
are the readiest antidotes. At a temperature of about 600° F., or a few
degrees below the melting point of lead, it boils and distils over like
water. This is the best method of procuring sulphuric acid free from the
saline and metallic matters with which it is sometimes contaminated.

The affinity of sulphuric acid for water is so strong that, when exposed
in an open saucer, it imbibes one-third of its weight from the
atmosphere in 24 hours, and fully six times its weight in a few months.
Hence it should be kept excluded from the air. If four parts, by weight,
of the strongest acid be suddenly mixed with one part of water, both
being at 50° F., the temperature of the mixture will rise to 300°;
while, on the other hand, if four parts of ice be mixed with one of
sulphuric acid, they immediately liquefy and sink the thermometer to 4°
below zero. From the great attraction existing between this acid and
water, a saucer of it is employed to effect the rapid condensation of
aqueous vapour as it exhales from a cup of water placed over it; both
standing under the exhausted receiver of an air-pump. By the cold
produced by this unchecked evaporation in vacuo, the water is speedily
frozen.

To determine the purity of sulphuric acid, let it be slowly heated to
the boiling point of water, and if any volatile acid matter be present,
it will evaporate, with its characteristic smell. The presence of saline
impurity, which is the common one, is discovered by evaporating a given
weight of it in a small capsule of platinum placed on red-hot cinders.
If more than two grains remain out of 500, the acid may be reckoned to
be impure. The best test for sulphuric acid, and the soluble salts into
which it enters, is the nitrate of baryta, of which 182 parts are
equivalent to 49 of the strongest liquid acid, or to 40 of the dry, as
it exists in crystallized sulphate of potassa. One twenty thousandth
part of a grain of the acid may be detected by the grayish-white cloud
which baryta forms with it. 100 parts of the concentrated acid are
neutralized by 143 parts of dry carbonate of potassa, and by 110 of dry
carbonate of soda, both perfectly pure.

Of all the acids, the sulphuric is most extensively used in the arts,
and is, in fact, the primary agent for obtaining almost all the others,
by disengaging them from their saline combinations. In this way, nitric,
muriatic, tartaric, acetic, and many other acids, are procured. It is
employed in the direct formation of alum, of the sulphates of copper,
zinc, potassa, soda; in that of sulphuric ether, of sugar by the
saccharification of starch, and in the preparation of phosphorus, &c. It
serves also for opening the pores of skins in tanning, for clearing the
surfaces of metals, for determining the nature of several salts by the
acid characters that are disengaged, &c.

According to the analysis of Dr. Thomson, the crystalline compound
deposited occasionally in the leaden chambers above described consists
of--

  Sulphurous acid   0·6387, or 3 atoms.
  Sulphuric acid    0·5290     2
  Nitric acid       0·3450     1 atom.
  Water             0·0733     1
  Sulphate of lead  0·0140.

He admits that the proportion of water is a little uncertain; and that
the presence of sulphurous acid was not proved by direct analysis. When
heated with water, the crystalline matter disengages nitrous gas in
abundance; lets fall some sulphate of lead; and the liquid is found to
be sulphuric acid. When heated without water, it is decomposed with
emission of nitrous gas and fuming nitric acid; leaving a liquid which,
mixed with water, produces a brisk effervescence, consisting chiefly of
nitrous gas.

The following TABLE shows the quantity of concentrated and dry sulphuric
acid in 100 parts of dilute, at different densities, by my experiments,
published in the Quarterly Journal of Science, for October, 1817:--

  +-------+---------+-------+
  |Liquid.|Sp. grav.| Dry.  |
  +-------+---------+-------+
  |  100  |  1·8460 |81·54  |
  |   99  |  1·8438 |80·72  |
  |   98  |  1·8415 |79·90  |
  |   97  |  1·8391 |79·09  |
  |   96  |  1·8366 |78·28  |
  |   95  |  1·8340 |77·46  |
  |   94  |  1·8288 |76·65  |
  |   93  |  1·8235 |75·83  |
  |   92  |  1·8181 |75·02  |
  |   91  |  1·8026 |74·20  |
  |   90  |  1·8070 |73·39  |
  |   89  |  1·7986 |72·57  |
  |   88  |  1·7901 |71·75  |
  |   87  |  1·7815 |70·94  |
  |   86  |  1·7728 |70·12  |
  |   85  |  1·7640 |69·31  |
  |   84  |  1·7540 |68·49  |
  |   83  |  1·7425 |67·68  |
  |   82  |  1·7315 |66·86  |
  |   81  |  1·7200 |66·05  |
  |   80  |  1·7080 |65·23  |
  |   79  |  1·6972 |64·42  |
  |   78  |  1·6860 |63·60  |
  |   77  |  1·6744 |62·78  |
  |   76  |  1·6624 |61·97  |
  |   75  |  1·6500 |61·15  |
  |   74  |  1·6415 |60·34  |
  |   73  |  1·6321 |59·52  |
  |   72  |  1·6204 |58·71  |
  |   71  |  1·6090 |57·89  |
  |   70  |  1·5975 |57·08  |
  |   69  |  1·5868 |56·26  |
  |   68  |  1·5760 |55·45  |
  |   67  |  1·5648 |54·63  |
  |   66  |  1·5503 |53·82  |
  |   65  |  1·5390 |53·00  |
  |   64  |  1·5280 |52·18  |
  |   63  |  1·5170 |51·37  |
  |   62  |  1·5066 |50·55  |
  |   61  |  1·4960 |49·74  |
  |   60  |  1·4860 |48·92  |
  |   59  |  1·4760 |48·11  |
  |   58  |  1·4660 |47·29  |
  |   57  |  1·4560 |46·48  |
  |   56  |  1·4460 |45·66  |
  |   55  |  1·4360 |44·85  |
  |   54  |  1·4265 |44·03  |
  |   53  |  1·4170 |43·22  |
  |   52  |  1·4073 |42·40  |
  |   51  |  1·3977 |41·58  |
  |   50  |  1·3884 |40·77  |
  |   49  |  1·3788 |39·95  |
  |   48  |  1·3697 |39·14  |
  |   47  |  1·3612 |38·32  |
  |   46  |  1·3530 |37·51  |
  |   45  |  1·3440 |36·69  |
  |   44  |  1·3345 |35·88  |
  |   43  |  1·3255 |35·06  |
  |   42  |  1·3165 |34·25  |
  |   41  |  1·3080 |33·43  |
  |   40  |  1·2999 |32·61  |
  |   39  |  1·2913 |31·80  |
  |   38  |  1·2826 |30·98  |
  |   37  |  1·2740 |30·17  |
  |   36  |  1·2654 |29·35  |
  |   35  |  1·2572 |28·54  |
  |   34  |  1·2490 |27·72  |
  |   33  |  1·2409 |26·91  |
  |   32  |  1·2334 |26·09  |
  |   31  |  1·2260 |25·28  |
  |   30  |  1·2184 |24·46  |
  |   29  |  1·2108 |23·65  |
  |   28  |  1·2032 |22·83  |
  |   27  |  1·1956 |22·01  |
  |   26  |  1·1876 |21·20  |
  |   25  |  1·1792 |20·38  |
  |   24  |  1·1706 |19·57  |
  |   23  |  1·1626 |18·75  |
  |   22  |  1·1549 |17·94  |
  |   21  |  1·1480 |17·12  |
  |   20  |  1·1410 |16·31  |
  |   19  |  1·1330 |15·49  |
  |   18  |  1·1246 |14·68  |
  |   17  |  1·1165 |13·86  |
  |   16  |  1·1090 |13·05  |
  |   15  |  1·1019 |12·23  |
  |   14  |  1·0953 |11·41  |
  |   13  |  1·0887 |10·60  |
  |   12  |  1·0809 | 9·78  |
  |   11  |  1·0743 | 8·97  |
  |   10  |  1·0682 | 8·15  |
  |    9  |  1·0614 | 7·34  |
  |    8  |  1·0544 | 6·52  |
  |    7  |  1·0477 | 5·71  |
  |    6  |  1·0405 | 4·89  |
  |    5  |  1·0336 | 4·08  |
  |    4  |  1·0268 | 3·26  |
  |    3  |  1·0206 | 2·446 |
  |    2  |  1·0140 | 1·63  |
  |    1  |  1·0074 | 0·8154|
  +-------+---------+-------+


SUMACH (Eng. and Fr.; _Schmack_, Germ.); is the powder of the leaves,
peduncles, and young branches of the _Rhus coriaria_, and _Rhus
cotinus_, shrubs which grow in Hungary, the Bannat, and the Illyrian
provinces. Both kinds contain tannin, with a little yellow
colouring-matter, and are a good deal employed for tanning
light-coloured leathers; but the first is the best. With mordants, it
dyes nearly the same colours as galls. In calico-printing, sumach
affords, with a mordant of tin, a yellow colour; with acetate of iron,
weak or strong, a gray or black; and with sulphate of zinc, a
brownish-yellow. A decoction of sumach reddens litmus paper strongly;
gives white flocks with the protomuriate of tin; pale-yellow flocks with
alum; blue flocks with red sulphate of iron, with an abundant
precipitate. In the south of France, the twigs and leaves of the
_Coriaria myrthifolia_ are used for dyeing, under the name of _rédoul_,
or _rodou_.


SWEEP-WASHER, is the person who extracts from the sweepings, potsherds,
&c., of refineries of silver and gold, the small residuum of precious
metal.


SYNTHESIS, is a Greek word, which signifies combination, and is applied
to the chemical action which unites dissimilar bodies into a uniform
compound; as sulphuric acid and lime, into gypsum; or chlorine and
sodium, into culinary salt.


SYRUP, is a solution of sugar in water. Cane-juice, concentrated to a
density of 1·300, forms a syrup which does not ferment in the transport
home from the West Indies, and may be boiled and refined at one step
into superior sugar-loaves, with eminent advantage to the planter, the
refiner, and the revenue.




T.


TABBYING, or WATERING, is the process of giving stuffs a wavy appearance
with the calender.


TACAMAHAC, is a resin obtained from the _Fagura octandra_, a tree which
grows in Mexico and the West Indies. It occurs in yellowish pieces, of a
strong smell, and a bitterish aromatic taste. That from the island of
Madagascar has a greenish tint.


TAFFETY, is a light silk fabric, with a considerable lustre or gloss.


TAFIA, is a variety of rum.


TALC, is a mineral genus, which is divided into two species, the common
and the indurated. The first occurs massive, disseminated in plates,
imitative, or crystallized in small six-sided tables. It is splendent,
pearly, or semi-metallic, translucent, flexible, but not elastic. It
yields to the nail; spec. gray. 2·77. Before the blowpipe, it first
whitens, and then fuses into an enamel globule. It consists of--silica,
62; magnesia, 27; alumina, 1·5; oxide of iron, 3·5; water, 6. Klaproth
found 2-1/2 per cent. of potash in it. It is found in beds of clay-slate
and mica-slate, in Aberdeenshire, Banffshire, Perthshire, Salzburg, the
Tyrol, and St. Gothard. It is an ingredient in rouge for the toilette,
communicating softness to the skin. It gives the flesh polish to soft
alabaster figures, and is also used in porcelain paste.

The second species, or talc-slate, has a greenish-gray colour; is
massive, with tabular fragments, translucent on the edges, soft, with a
white streak; easily cut or broken, but is not flexible; and has a
greasy feel. It occurs in the same localities as the preceding. It is
employed in the porcelain and crayon manufactures; as also as a crayon
itself, by carpenters, tailors, and glaziers.


TALLOW (_Suif_, Fr.; _Talg_, Germ.); is the concrete fat of quadrupeds
and man. That of the ox consists of 76 parts of stearine, and 24 of
oleine; that of the sheep contains somewhat more stearine. See FAT and
STEARINE.

Tallow imported into the United Kingdom, in 1836, 1,186,364 cwts. 1 qr.
4 lbs.; in 1837, 1,308,734 cwts. 1 qr. 4 lbs. Retained for home
consumption, in 1836, 1,318,678 cwts. 1 qr. 25 lbs.; in 1837, 1,294,009
cwts. 2 qrs. 21 lbs. Duty received, in 1836, _£_208,284; in 1837,
_£_204,377.


TALLOW, PINEY. See PINEY TALLOW.


TAMPING, is a term used by miners to express the filling up of the hole
which they have bored in a rock, for the purpose of blasting it with
gunpowder. See MINES.


TAN, or TANNIC ACID. (_Tannin_, Fr.; _Gerbstoff_, Germ.) See its
preparation and properties described under GALLS.

The barks replete with this principle should be stripped with hatchets
and bills, from the trunk and branches of trees, not less than 30 years
of age, in spring, when their sap flows most freely. Trees are also
sometimes barked in autumn, and left standing, whereby they cease to
vegetate, and perish ere long; but afford, it is thought, a more compact
timber. This operation is, however, too troublesome to be generally
practised, and therefore the bark is commonly obtained from felled
trees; and it is richer in tannin the older they are. The bark mill is
described in Gregory’s _Mechanics_, and other similar works.

The following TABLE shows the quantity of extractive matter and tan in
100 parts of the several substances:--

  +----------------------------------+--------+----------+-------------+
  |           Substances.            |In 480, |In about  |In 100 parts,|
  |                                  |by Davy.|8 oz., by |by Cadet de  |
  |                                  |        |Biggins.  |Gassincourt. |
  +----------------------------------+--------+----------+-------------+
  |White inner bark of old oak       |   72   |          |      21     |
  |  Do. young oak                   |   77   |          |             |
  |  Do. Spanish chestnut            |   63   |    30    |             |
  |  Do. Leicester willow            |   79   |          |             |
  |Coloured or middle bark of oak    |   19   |          |             |
  |  Do. Spanish chestnut            |   14   |          |             |
  |  Do. Leicester willow            |   16   |          |             |
  |Entire bark of oak                |   29   |          |             |
  |  Do. Spanish chestnut            |   21   |          |             |
  |  Do. Leicester willow            |   33   |   109    |             |
  |  Do. Elm                         |   13   |    28    |             |
  |  Do. Common willow               |   11   |boughs, 31|             |
  |Sicilian sumach                   |   78   |   158    |             |
  |Malaga sumach                     |   79   |          |             |
  |Souchong tea                      |   48   |          |             |
  |Green tea                         |   41   |          |             |
  |Bombay catechu                    |  261   |          |             |
  |Bengal catechu                    |  231   |          |             |
  |Nut-galls                         |  127   |          |      46     |
  |Bark of oak, cut in winter        |   --   |    30    |             |
  |  Do. beech                       |   --   |    31    |             |
  |  Do. Elder                       |   --   |    41    |             |
  |  Do. Plum-tree                   |   --   |    58    |             |
  |Bark of the trunk of Willow       |   --   |    52    |             |
  |  Do. Sycamore                    |   --   |    53    |      16     |
  |Bark of Birch                     |   --   |    54    |             |
  |Bark of Cherry-tree               |   --   |    59    |      24     |
  |  Do. Sallow                      |   --   |    59    |             |
  |  Do. Poplar                      |   --   |    76    |             |
  |  Do. Hazel                       |   --   |    79    |             |
  |  Do. Ash                         |   --   |    82    |             |
  |  Do. trunk of Span. chestnut     |   --   |    98    |             |
  |  Do. Smooth oak                  |   --   |   104    |             |
  |  Do. Oak, cut in spring          |   --   |   108    |             |
  |Root of Tormentil                 |   --   |          |      46     |
  |Cornus sanguinea of Canada        |   --   |          |      44     |
  |Bark of Alder                     |   --   |          |      36     |
  |  Do. Apricot                     |   --   |          |      32     |
  |  Do. Pomegranate                 |   --   |          |      32     |
  |  Do. Cornish cherry-tree         |   --   |          |      19     |
  |  Do. Weeping willow              |   --   |          |      16     |
  |  Do. Bohemian olive              |   --   |          |      14     |
  |  Do. Tan shrub with myrtle leaves|   --   |          |      13     |
  |  Do. Virginian sumach            |   --   |          |      10     |
  |  Do. Green oak                   |   --   |          |      10     |
  |  Do. Service-tree                |   --   |          |       8     |
  |  Do. Rose chestnut of Amer.      |   --   |          |       8     |
  |  Do. Rose chestnut               |   --   |          |       6     |
  |  Do. Rose chestnut of Carolina   |   --   |          |       6     |
  |  Do. Sumach of Carolina          |   --   |          |       5     |
  +----------------------------------+--------+----------+-------------+


TANNING (_Tanner_, Fr.; _Gärberei_, Germ.); is the art of converting
skin into LEATHER, which see. It has been ascertained, beyond a doubt,
that “the saturated infusions of astringent barks contain much less
extractive matter, in proportion to their tannin, than the weak
infusions; and when skin is quickly tanned (in the former), common
experience shows that it produces leather less durable than leather
slowly formed.”[66] The older tanners, who prided themselves on
producing a substantial article, were so much impressed with the
advantages of slowly impregnating skin with astringent matter, that they
employed no concentrated infusion (ooze) in their pits, but stratified
the skins with abundance of ground bark, and covered them with soft
water, knowing that its active principles are very soluble, and that, by
being gradually extracted, they would penetrate uniformly the whole of
the animal fibres, instead of acting chiefly upon the surface, and
making brittle leather, as the strong infusions never fail to do. In
fact, 100 pounds of skin, quickly tanned in a strong infusion of bark,
produce 137 of leather; while 100 pounds, slowly tanned in a weak
infusion, produce only 117-1/2. The additional 19-1/2 pounds weight in
the former case serve merely to swell the tanner’s bill, while they
deteriorate his leather, and cause it to contain much less of the
textile animal solid. Leather thus highly charged with tannin, is,
moreover, so spongy as to allow moisture to pass readily through its
pores, to the great discomfort and danger of persons who wear shoes made
of it. That the saving of time, and the increase of product, are
temptations strong enough to induce many modern tanners to steep their
skins in a succession of strong infusions of bark, is sufficiently
intelligible; but that any shoemaker should be so ignorant or so foolish
as to proclaim that his leather is made by a process so injurious to its
quality, is unaccountably stupid.

  [66] Sir H. Davy, on the Operation of Astringent Vegetables in
  Tanning.--_Phil. Trans._ 1803.


TANTALUM, is the rare metal; also called COLUMBIUM.


TAPESTRY, is an ornamental figured textile fabric of worsted or silk,
for lining the walls of apartments; of which the most famous is that of
the Gobelins Royal Manufactory, near Paris.


TAPIOCA, is a modification of starch, partially converted into gum, by
heating and stirring cassava upon iron plates. See CASSAVA and STARCH.


TAR (_Goudron_, Fr.; _Ther_, Germ.); is the viscid, brown-black,
resino-oleaginous compound, obtained by distilling wood in close
vessels, or in ovens of a peculiar construction. See CHARCOAL, PITCOAL,
COKING OF, and PYROLIGNOUS ACID. According to Reichenbach, tar contains
the peculiar proximate principles, _paraffine_, _eupion_, _creosote_,
_picamar_, _pittacal_, besides pyrogenous resin, or _pyretine_,
pyrogenous oil, or _pyroleine_, and vinegar. The resin, oil, and vinegar
are called empyreumatic, in common language.

Tar imported into the United Kingdom, in 1836, 9,797 lsts. 8 brls.; in
1837, 11,480 lsts. 1 brl. Retained for home consumption, in 1836, 9,639
lsts. 8 brls.; in 1837, 11,686 lsts. 8 brls. Duty received, in 1836,
_£_7,231; in 1837, _£_8,775.


TARRAS; see CEMENT, and MORTAR, HYDRAULIC.


TARTAR (_Tartre_, Fr.; _Weinstein_, Germ.); called also argal or argol;
is the crude bitartrate of potassa, which exists in the juice of the
grape, and is deposited from wines in their fermenting casks, being
precipitated in proportion as the alcohol is formed, in consequence of
its insolubility in that liquid. There are two sorts of argal known in
commerce, the white, and the red; the former, which is of a pale-pinkish
colour, is the crust let fall by white wines; the latter is a dark-red,
from red wines.

The crude tartar is purified, or converted into cream of tartar, at
Montpellier, by the following process:--

The argal having been ground under vertical mill-stones, and sifted, one
part of it is boiled with 15 of water, in conical copper kettles, tinned
on the inside. As soon as it is dissolved, 3-1/2 parts of ground
pipe-clay are introduced. The solution being well stirred, and then
settled, is drawn off into crystallizing vessels, to cool; the crystals
found concreted on the sides and bottom are picked out, washed with
water, and dried. The mother-water is employed upon a fresh portion of
argal. The crystals of the first crop are re-dissolved, re-crystallized,
and exposed upon stretched canvas to the sun and air, to be bleached.
The clay serves to abstract the colouring-matter. The crystals formed
upon the surface are the whitest, whence the name cream of tartar is
derived.

Purified tartar, the bitartrate of potassa, is thus obtained in hard
clusters of small colourless crystals, which, examined by a lens, are
seen to be transparent 4-sided prisms. It has no smell, but a feebly
acid taste; is unchangeable in the air, has a specific gravity of 1·953,
dissolves in 16 parts of boiling water, and in 200 parts at 60° F. It is
insoluble in alcohol. It consists of 24·956 potassa, 70·276 tartaric
acid, and 4·768 water. It affords, by dry distillation, pyrotartaric
acid, and an empyreumatic oil; while carbonate of potassa remains
associated with much charcoal in the retort, constituting black flux.
Tartar is used in dyeing, medicine, and for extracting--


TARTARIC ACID. (_Acide tartarique_, Fr.; _Weinsteinsäure_, Germ.) This
is prepared by adding gradually to a boiling-hot solution of 100 parts
of tartar, in a large copper boiler, 26 of chalk, made into a smooth pap
with water. A brisk effervescence ensues, by the disengagement of the
carbonic acid of the chalk, while its base combines with the acid excess
in the tartar, and forms an insoluble precipitate of tartrate of lime.
The supernatant liquor, which is a solution of neutral tartrate of
potassa, must be drawn off by a syphon, and decomposed by a solution of
chloride of calcium (muriate of lime). 28-1/2 parts of the dry chloride
are sufficient for 100 of tartar. The tartrate of lime, from both
processes, is to be washed with water, drained, and then subjected, in a
leaden cistern, to the action of 49 parts of sulphuric acid, previously
diluted with 8 times its weight of water: 100 of dry tartrate take 75 of
oil of vitriol. This mixture, after digestion for a few days, is
converted into sulphate of lime and tartaric acid. The latter is to be
separated from the former by decantation, filtration through canvas, and
edulcoration of the sulphate of lime upon the filter.

The clear acid is to be concentrated in leaden pans, by a moderate heat,
till it acquires the density of 40° B. (spec. grav. 1·38), and then it
is run off, clear from any sediment, into leaden or stoneware vessels,
which are set in a dry stove-room for it to crystallize. The crystals,
being re-dissolved and re-crystallized, become colourless 6-sided
prisms. In decomposing the tartrate of lime, a very slight excess of
sulphuric acid must be employed; because pure tartaric acid would
dissolve any tartrate of lime that may escape decomposition. Bone black,
previously freed from its carbonate and phosphate of lime, by muriatic
acid, is sometimes employed to blanch the coloured solutions of the
first crystals. Tartaric acid contains nearly 9 per cent. of combined
water. It is soluble in two parts of water at 60°, and in its own weight
of boiling water. In its dry state, as it exists in the tartrate of lime
or lead, it consists of 36·8 of carbon, 3 of hydrogen, and 60·2 of
oxygen. It is much employed in calico-printing, and for making sodaic
powders.


TARTRATES, are salts composed of tartaric acid, and oxidized bases, in
equivalent proportions.


TAWING, is the process of preparing the white skins of the sheep doe,
&c. See LEATHER.


TEA, _green_, contains 34·6 parts of tannin, 5·9 of gum, 5·7 of
vegetable albumine, 51·3 of ligneous fibre, with 2·5 of loss; and
_black_ tea contains 40·6 of tannin, 6·3 of gum, 6·4 of vegetable
albumine, 44·8 of ligneous fibre, with 2 of loss. The ashes
contain silica, carbonate of lime, magnesia, and chloride of
potassium.--_Frank._ Davy obtained 32·5 of extract from Souchong tea; of
which 10 were precipitated by gelatine. He found 8·5 only of tannin in
green tea. The latter chemist is most to be depended upon. Chemical
analysis has not yet discovered that principle in tea, to which its
exciting property is due.

_The Chinese method of making Black Tea in Upper Assam._[67]--In the
first place, the youngest and most tender leaves are gathered; but when
there are many hands and a great quantity of leaves to be collected, the
people employed nip off with the forefinger and thumb the fine end of
the branch with about four leaves on, and sometimes even more, if they
look tender. These are all brought to the place where they are to be
converted into tea; they are then put into a large, circular,
open-worked bamboo basket, having a rim all round, two fingers broad.
The leaves are thinly scattered in these baskets, and then placed in a
framework of bamboo, in all appearance like the side of an Indian hut
without grass, resting on posts, 2 feet from the ground, with an angle
of about 25°. The baskets with leaves are put in this frame to dry in
the sun, and are pushed up and brought down by a long bamboo with a
circular piece of wood at the end. The leaves are permitted to dry about
two hours, being occasionally turned; but the time required for this
process depends on the heat of the sun. When they begin to have a
slightly withered appearance, they are taken down and brought into the
house, where they are placed on a frame to cool for half an hour. They
are then put into smaller baskets of the same kind as the former, and
placed on a stand. People are now employed to soften the leaves still
more, by gently clapping them between their hands, with their fingers
and thumb extended, and tossing them up and letting them fall, for about
five or ten minutes. They are then again put on the frame during half an
hour, and brought down and clapped with the hands as before. This is
done three successive times, until the leaves become to the touch like
soft leather; the beating and putting away being said to give the tea
the black colour and bitter flavour. After this the tea is put into hot
cast-iron pans, which are fixed in a circular mud fireplace, so that the
flame cannot ascend round the pan to incommode the operator. This pan is
well heated by a straw or bamboo fire to a certain degree. About two
pounds of the leaves are then put into each hot pan, and spread in such
a manner that all the leaves may get the same degree of heat. They are
every now and then briskly turned with the naked hand, to prevent a leaf
from being burnt. When the leaves become inconveniently hot to the hand,
they are quickly taken out and delivered to another man with a
close-worked bamboo basket ready to receive them. A few leaves that may
have been left behind are smartly brushed out with a bamboo broom; all
this time a brisk fire is kept up under the pan. After the pan has been
used in this manner three or four times, a bucket of cold water is
thrown in, and a soft brickbat and bamboo broom used, to give it a good
scouring out; the water is thrown out of the pan by the brush on one
side, the pan itself being never taken off. The leaves, all hot on the
bamboo basket, are laid on a table that has a narrow rim on its back, to
prevent these baskets from slipping off when pushed against it. The two
pounds of hot leaves are now divided into two or three parcels, and
distributed to as many men, who stand up to the table with the leaves
right before them, and each placing his legs close together; the leaves
are next collected into a ball, which he gently grasps in his left hand,
with the thumb extended, the fingers close together, and the hand
resting on the little finger. The right hand must be extended in the
same manner as the left, but with the palm turned downwards, resting on
the top of the ball of tea leaves. Both hands are now employed to roll
and propel the ball along; the left hand pushing it on, and allowing it
to revolve as it moves; the right hand also pushes it forward, resting
on it with some force, and keeping it down to express the juice which
the leaves contain. The art lies here in giving the ball a circular
motion, and permitting it to turn under and in the hand two or three
whole revolutions, before the arms are extended to their full length,
and drawing the ball of leaves quickly back without leaving a leaf
behind, being rolled for about five minutes in this way. The ball of tea
leaves is from time to time gently and delicately opened with the
fingers, lifted as high as the face, and then allowed to fall again.
This is done two or three times, to separate the leaves; and afterwards
the basket with the leaves is lifted up as often, and receives a
circular shake to bring these towards the centre. The leaves are now
taken back to the hot pans, and spread out in them as before, being
again turned with the naked hand, and when hot taken out and rolled;
after which they are put into the drying basket, and spread on a sieve
which is in the centre of the basket, and the whole placed over a
charcoal fire. The fire is very nicely regulated; there must not be the
least smoke, and the charcoal should be well picked.

  [67] By C. A. Bruce, superintendent of tea culture.

When the fire is lighted, it is fanned until it gets a fine red glare,
and the smoke is all gone off; being every now and then stirred and the
coals brought into the centre, so as to leave the outer edge low. When
the leaves are put into the drying basket, they are gently separated by
lifting them up with the fingers of both hands extended far apart, and
allowing them to fall down again; they are placed 3 or 4 inches deep on
the sieve, leaving a passage in the centre for the hot air to pass.
Before it is put over the fire, the drying basket receives a smart slap
with both hands in the act of lifting it up, which is done to shake down
any leaves that might otherwise drop through the sieve, or to prevent
them from falling into the fire and occasioning a smoke, which would
affect and spoil the tea. This slap on the basket is invariably applied
throughout the stages of the tea manufacture. There is always a large
basket underneath to receive the small leaves that fall, which are
afterwards collected, dried, and added to the other tea; in no case are
the baskets or sieves permitted to touch or remain on the ground, but
always laid on a receiver with three legs. After the leaves have been
half dried in the drying basket, and while they are still soft, they are
taken off the fire and put into large open-worked baskets, and then put
on the shelf, in order that the tea may improve in colour.

Next day the leaves are all sorted into large, middling, and small;
sometimes there are four sorts. All these, the Chinese informed me,
become so many different kinds of teas; the smallest leaves they called
Pha-ho, the second Pow-chong, the third Su-chong, and the fourth, or the
largest leaves, Toy-chong. After this assortment they are again put on
the sieve in the drying basket (taking great care not to mix the sorts),
and on the fire, as on the preceding day; but now very little more than
will cover the bottom of the sieve is put in at one time, the same care
of the fire is taken as before, and the same precaution of tapping the
drying basket every now and then. The tea is taken off the fire with the
nicest care, for fear of any particle of the tea falling into it.
Whenever the drying basket is taken off, it is put on the receiver, the
sieve in the drying basket taken out, the tea turned over, the sieve
replaced, the tap given, and the basket placed again over the fire. As
the tea becomes crisp, it is taken out and thrown into a large receiving
basket, until all the quantity on hand has become alike dried and crisp;
from which basket it is again removed into the drying basket, but now in
much larger quantities. It is then piled up eight and ten inches high on
the sieve in the drying basket; in the centre a small passage is left
for the hot air to ascend; the fire that was before bright and clear,
has now ashes thrown on it to deaden its effect, and the shakings that
have been collected are put on the top of all; the tap is given, and the
basket with the greatest care is put over the fire. Another basket is
placed over the whole, to throw back any heat that may ascend. Now and
then it is taken off, and put on the receiver; the hands, with the
fingers wide apart, are run down the sides of the basket to the sieve,
and the tea gently turned over, the passage in the centre again made,
&c., and the basket again placed on the fire. It is from time to time
examined, and when the leaves have become so crisp that they break by
the slightest pressure of the fingers, it is taken off, when the tea is
ready. All the different kinds of leaves underwent the same operation.
The tea is now little by little put into boxes, and first pressed down
with the hands and then with the feet (clean stockings having been
previously put on).

There is a small room inside of the tea-house, 7 cubits square and 5
high, having bamboos laid across on the top to support a net work of
bamboo, and the sides of the room smeared with mud to exclude the air.
When there is wet weather, and the leaves cannot be dried in the sun,
they are laid out on the top of this room, on the network, on an iron
pan, the same as is used to heat the leaves; some fire is put into it,
either of grass or bamboo, so that the flame may ascend high; the pan is
put on a square wooden frame, that has wooden rollers on its legs, and
pushed round and round this little room by one man, while another feeds
the fire, the leaves on the top being occasionally turned; when they are
a little withered, the fire is taken away, and the leaves brought down
and manufactured into tea, in the same manner as if it had been dried in
the sun. But this is not a good plan, and never had recourse to, if it
can possibly be avoided.

Tea imported into the United Kingdom, in 1836, 49,307,701 lbs.; in 1837,
36,765,735 lbs. Retained for home consumption, in 1836, 49,841,507 lbs.;
in 1837, 31,872 lbs. Duty received, in 1836, _£_4,728,600; in 1837,
_£_3,319,665.


TEASEL, the head of the thistle (_Dipsacus_), is employed to raise the
nap of cloth. See WOOLLEN MANUFACTURE.


TEETH. See BONES.


TELLURIUM, is a metal, too rare and high-priced to be used in the arts.


TERRA-COTTA, literally baked clay, is the name given to statues,
architectural decorations, figures, vases, &c., modelled or cast in a
paste made of pipe or potter’s clay and a fine-grained colourless sand,
from Ryegate, with pulverized potsherds, slowly dried in the air, and
afterwards fired to a stony hardness in a proper kiln. See STONE,
ARTIFICIAL.


TERRA DI SIENA, is a brown ferruginous ochre, employed in painting.


TESTS, are chemical reagents of any kind, which indicate, by special
characters, the nature of any substance, simple or compound. See ASSAY,
the several metals, acids, &c.

[Illustration: 1103 1104]


TEXTILE FABRICS. The first business of the weaver is to adapt those
parts of his loom which move the warp, to the formation of the various
kinds of ornamental figures which the cloth is intended to exhibit. This
subject is called the _draught_, drawing or reading in, and the cording
of looms. In every species of weaving, whether direct or cross, the
whole difference of pattern or effect is produced, either by the
succession in which the threads of warp are introduced into the
heddles, or by the succession in which those heddles are moved in the
working. The heddles being stretched between two shafts of wood, all the
heddles connected by the same shafts are called a leaf; and as the
operation of introducing the warp into any number of leaves is called
drawing a warp, the plan of succession is called the draught. When this
operation has been performed correctly, the next part of the weaver’s
business is to connect the different leaves with the levers or treddles
by which they are to be moved, so that one or more may be raised or sunk
by every treddle successively, as may be required to produce the
peculiar pattern. These connections being made by coupling the different
parts of the apparatus by cords, this operation is called the cording.
In order to direct the operator in this part of his business, especially
if previously unacquainted with the particular pattern upon which he is
employed, plans are drawn upon paper, specimens of which will be found
in _figs._ 1103, 1104., &c. These plans are horizontal sections of a
loom, the heddles being represented across the paper at _a_, and the
treddles under them, and crossing them at right angles, at _b_. In
_figs._ 1103. and 1104. they are represented as if they were distinct
pieces of wood, those across being the under shaft of each leaf of
heddles, and those at the left hand the treddles. See WEAVING. In actual
weaving, the treddles are placed at right angles to the heddles, the
sinking cords descending perpendicularly as nearly as possible to the
centre of the latter. Placing them at the left hand, therefore, is only
for ready inspection, and for practical convenience. At _c_ a few
threads of warp are shown as they pass through the heddles, and the
thick lines denote the leaf with which each thread is connected. Thus,
in _fig._ 1103., the right-hand thread, next to _a_, passes through the
eye of a heddle upon the back leaf, and is disconnected with all the
other leaves; the next thread passes through a heddle on the second
leaf; the third, through the third leaf; the fourth, through the fourth
leaf; and the fifth, through the fifth or front leaf. One set of the
draught being now completed, the weaver recommences with the back leaf,
and proceeds in the same succession again to the front. Two sets of the
draught are represented in this figure, and the same succession, it is
understood by weavers (who seldom draw more than one set), must be
repeated until all the warp is included. When they proceed to apply the
cords, the right-hand part of the plan at _b_ serves as a guide. In all
the plans shown by these figures, excepting one which shall be noticed,
a connexion must be formed, by cording, between every leaf of heddles
and every treddle; for all the leaves must either rise or sink. The
raising motion is effected by coupling the leaf to one end of its
correspondent top lever; the other end of this lever is tied to the long
march below, and this to the treddle. The sinking connexion is carried
directly from under the leaf to the treddle. To direct a weaver which of
these connexions is to be formed with each treddle, a black spot is
placed when a leaf is to be raised, where the leaf and treddle intersect
each other upon the plan, and the sinking connexions are left blank. For
example, to cord, the treddle 1, to the back leaf, put a raising cord,
and to each of the other four, sinking cords; for the treddle 2, raise
the second leaf, and sink the remaining four, and so of the rest; the
spot always denoting the leaf or leaves to be raised. The _figs._ 1103.
and 1104. are drawn for the purpose of rendering the general principle
of this kind of plans familiar to those who have not been previously
acquainted with them; but those who have been accustomed to manufacture
and weave ornamented cloths, never consume time by representing either
heddles or treddles as solid or distinct bodies. They content themselves
with ruling a number of lines across a piece of paper, sufficient to
make the intervals between these lines represent the number of leaves
required. Upon these intervals, they merely mark the succession of the
draught, without producing every line to resemble a thread of warp. At
the left hand, they draw as many lines across the former as will afford
an interval for each treddle; and in the squares produced by the
intersections of these lines, they place the dots, spots, or ciphers
which denote the raising cords. It is also common to continue the cross
lines which denote the treddle a considerable length beyond the
intersections, and to mark by dots, placed diagonally in the intervals,
the order or succession in which the treddles are to be pressed down in
weaving. The former of these modes has been adopted in the remaining
_figs._ to 1112.; but to save room, the latter has been avoided, and the
succession marked by the order of the figures under the intervals which
denote the treddles.

Some explanation of the various kinds of fanciful cloths represented by
these plans, may serve further to illustrate this subject, which is,
perhaps, the most important of any connected with the manufacture of
cloth, and will also enable a person who thoroughly studies them,
readily to acquire a competent knowledge of the other varieties in
weaving, which are boundless. _Figs._ 1103. and 1104. represent the
draught and cording of the two varieties of tweeled cloth wrought with
five leaves of heddles. The first is the regular or run tweel, which, as
every leaf rises in regular succession, while the rest are sunk,
interweaves the warp and woof only at every fifth interval, and as the
succession is uniform, the cloth when woven, presents the appearance of
parallel diagonal lines, at an angle of about 45° over the whole
surface. A tweel may have the regularity of its diagonal lines broken by
applying the cording as in _fig._ 1104. It will be observed, that in
both figures the draught of the warp is precisely the same, and that the
whole difference of the two plans consists in the order of placing the
spots denoting the raising cords, the first being regular and
successive, and the second alternate.

[Illustration: 1105 1106 1107 1108]

_Figs._ 1105. and 1106. are the regular and broken tweels which may be
produced with eight leaves. This properly is the tweel denominated satin
in the silk manufacture, although many webs of silk wrought with only
five leaves receive that appellation. Some of the finest Florentine
silks are tweeled with sixteen leaves. When the broken tweel of eight
leaves is used, the effect is much superior to what could be produced by
a smaller number; for in this, two leaves are passed in every interval,
which gives a much nearer resemblance to plain cloth than the others.
For this reason it is preferred in weaving the finest damasks. The
draught of the eight-leaf tweel differs in nothing from the others,
excepting in the number of leaves. The difference of the cording in the
broken tweel, will appear by inspecting the cyphers which mark the
raising cords, and comparing them with those of the broken tweel of five
leaves. _Fig._ 1107. represents the draught and cording of striped
dimity of a tweel of five leaves. This is the most simple species of
fanciful tweeling. It consists of ten leaves, or double the number of
the common tweel. These ten leaves are moved by only five treddles, in
the same manner as a common tweel. The stripe is formed by one set, of
the leaves flushing the warp, and the other set, the woof. The figure
represents a stripe formed by ten threads, alternately drawn through
each of the two sets of leaves. In this case, the stripe and the
intervals will be equally broad, and what is the stripe upon one side of
the cloth, will be the interval upon the other, and _vice versâ_. But
great variety of patterns may be introduced by drawing the warp in
greater or smaller portions through either set. The tweel is of the
regular kind, but may be broken by placing the cording as in _fig._
1104. It will be observed that the cording-marks of the lower or front
leaves are exactly the converse of the other set; for where a raising
mark is placed upon one, it is marked for sinking in the other; that is
to say, the mark is omitted; and all leaves which sink in the one, are
marked for raising in the other: thus, one thread rises in succession in
the back set, and four sink; but in the front set, four rise, and only
one sinks. The woof, of course, passing over the four sunk threads, and
under the raised one, in the first instance, is flushed above; but where
the reverse takes place, as in the second, it is flushed below; and thus
the appearance of a stripe is formed. The analogy subsisting between
striped dimity and dornock, is so great, that before noticing the plan
for fancy dimity, it may be proper to allude to the dornock, the plan of
which is represented by _fig._ 1108.

The draught of dornock is precisely the same in every respect with that
of striped dimity. It also consists of two sets of tweeling-heddles,
whether three, four, or five leaves are used for each set. The
right-hand set of treddles is also corded exactly in the same way, as
will appear by comparing them. But as the dimity is a continued stripe
from the beginning to the end of the web, only five treddles are
required to move ten leaves. The dornock being checker-work, the weaver
must possess the power of reversing this at pleasure. He therefore adds
five more treddles, the cording of which is exactly the reverse of the
former; that is to say, the back leaves, in the former case, having one
leaf raised, and four sunk, have, by working with these additional
treddles, one leaf sunk and four leaves raised. The front leaves are in
the same manner reversed, and the mounting is complete. So long as the
weaver continues to work with either set, a stripe will be formed, as in
the dimity; but when he changes his feet from one set to the other, the
whole effect is reversed, and the checkers formed. The dornock pattern
upon the design-paper, _fig._ 1108., may be thus explained: let every
square of the design represent five threads upon either set of the
heddles, which are said by weavers to be once over the draught,
supposing the tweel to be one of five leaves; draw three parallel lines,
as under, to form two intervals, each representing one of the sets; the
draught will then be as follows:--

  +-------------------------------+
  |  4   1   4   1   1   4   1    |
  +-------------------------------+
  |    4   4   1   1   1   4   4  |
  +-------------------------------+

The above is exactly so much of the pattern as is there laid down, to
show its appearance; but one whole range of the pattern is completed by
the figure 1, nearest to the right hand upon the lower interval between
the lines, and the remaining figures, nearer to the right, form the
beginning of a second range or set. These are to be repeated in the same
way across the whole warp. The lower interval represents the five front
leaves; the upper interval, the five back ones. The first figure 4,
denotes that five threads are to be successively drawn upon the back
leaves, and this operation repeated four times. The first figure 4, in
the lower interval, expresses that the same is to be done upon the front
leaves; and each figure, by its diagonal position, shows how often, and
in what succession, five threads are to be drawn upon the leaves which
the interval in which it is placed represents.

Dornocks of more extensive patterns are sometimes woven with 3, 4, 5,
and even 6 sets of leaves; but after the leaves exceed 15 in number,
they both occupy an inconvenient space, and are very unwieldy to work.
For these reasons the diaper harness is in almost every instance
preferred.

[Illustration: 1109]

_Fig._ 1109. represents the draught and cording of a fanciful species of
dimity, in which it will be observed that the warp is not drawn directly
from the back to the front leaf, as in the former examples; but when it
has arrived at either external leaf, the draught is reversed, and
returns gradually to the other. The same draught is frequently used in
tweeling, when it is wished that the diagonal lines should appear upon
the cloth in a zigzag direction. This plan exhibits the draught and
cording which will produce the pattern upon the design-paper in _fig._
1103. _a_. Were all the squares produced by the intersection of the
lines denoting the leaves and treddles, where the raised dots are
placed, filled the same as on the design, they would produce the effect
of exactly one-fourth of that pattern. This is caused by the reversing
of the draught, which gives the other side reversed as on the design;
and when all the treddles, from 1 to 16, have been successively used in
the working, one-half of the pattern will become complete. The weaver
then goes again over his treddles, in the reversed order of the numbers,
from 17 to 30, when the other half of the pattern will be completed.
From this similarity of the cording to the design, it is easy, when a
design is given, to make out the draught and cording proper to work it;
and when the cording is given, to see its effect upon the design.

[Illustration: 1110]

_Fig._ 1110. represents the draught of the diaper mounting, and the
cording of the front leaves, which are moved by treddles. From the plan,
it will appear that 5 threads are included in every mail of the harness,
and that these are drawn in single threads through the front leaves. The
cording forms an exception to the general rules, that when one or more
leaves are raised, all the rest must be sunk; for in this instance, one
leaf rises, one sinks, and three remain stationary. An additional mark,
therefore, is used in this plan. The dots, as formerly, denote raising
cords; the blanks, sinking cords; and where the cord is to be totally
omitted, the cross marks × are placed.

[Illustration: 1111]

_Fig._ 1111. is the draught and cording of a spot whose two sides are
similar, but reversed. That upon the plan forms a diamond, similar to
the one drawn upon the design paper in the diagram, but smaller in size.
The draught here is reversed, as in the dimity plan, and the treading is
also to be reversed, after arriving at 6, to complete the diamond. Like
it, too, the raising marks form one-fourth of the pattern. In weaving
spots, they are commonly placed at intervals, with a portion of plain
cloth between them, and in alternate rows, the spots of one row being
between those of the other. But as intervals of plain cloth must take
place, both by the warp and woof, 2 leaves are added for that purpose.
The front, or ground leaf, includes every second thread of the whole
warp; the second, or plain leaf, that part which forms the intervals by
the warp. The remaining leaves form the spots; the first six being
allotted to one row of spots, and the second six to the next row; where
each spot is in the centre between the former. The reversed draught of
the first is shown entire, and is succeeded by 12 threads of plain.
One-half of the draught of the next row is then given, which is to be
completed exactly like the first, and succeeded by 12 threads more of
plain; when, one set of the pattern being finished, the same succession
is to be repeated over the whole warp. As spots are formed by inserting
woof of coarser dimensions than that which forms the fabric, every
second thread only is allotted for the spotting. Those included in the
front, or ground leaf, are represented by lines, and the spot threads
between them, by marks in the intervals, as in the other plans.

The treddles necessary to work this spot are, in number, 14. Of these,
the two in the centre, _a_, _b_, when pressed alternately, will produce
plain cloth; for _b_ raises the front leaf, which includes half of the
warp, and sinks all the rest; while _a_ exactly reverses the operation.
The spot-treddles on the right hand work the row contained in the first
six spot-leaves; and those upon the left hand, the row contained in the
second six. In working spots, one thread, or shot of spotting-woof, and
two of plain, are successively inserted, by means of two separate
shuttles.

[Illustration: 1112]

Dissimilar spots, are those whose sides are quite different from each
other. The draught only of these is represented by _fig._ 1112. The
cording depends entirely upon the figure.

[Illustration: 1113]

_Fig._ 1113. represents any solid body composed of parts _lashed_
together. If the darkened squares be supposed to be beams of wood,
connected by cordage, they will give a precise idea of textile fabric.
The beams cannot come into actual contact, because, if the _lashing_
cords were as fine even as human hairs, they must still require space.
The thickness is that of one beam and one cord; but if the cords touch
each other, it may then be one beam and two cords; but it is not
possible in practical weaving to bring every thread of weft into actual
contact. It may therefore be assumed, that the thickness is equal to the
diameter of one thread of the warp, added to that of one yarn of the
weft; and when these are equal, the thickness of the cloth is double of
that diameter. Denser cloth would not be sufficiently pliant or
flexible.

[Illustration: 1114]

_Fig._ 1114. is a representation of a section of cloth of an open
fabric, where the round dots which represent the warp are placed at a
considerable distance from each other.

[Illustration: 1115]

_Fig._ 1115. may be supposed a plain fabric of that description which
approaches the most nearly to any idea we can form of the most dense or
close contact of which yarn can be made susceptible. Here the warp is
supposed to be so tightly stretched in the loom as to retain entirely
the parallel state, without any curvature, and the whole flexure is
therefore given to the woof. This mode of weaving can never really
exist; but if the warp be sufficiently strong to bear any tight
stretching, and the woof be spun very soft and flexible, something very
near it may be produced. This way of making cloth is well fitted for
those goods which require to give considerable warmth; but they are
sometimes the means of very gross fraud and imposition; for if the warp
is made of very slender threads, and the woof of slackly twisted cotton
or woollen yarn, where the fibrils of the stuff, being but slightly
brought into contact, are rough and oozy, a great appearance of
thickness and strength may be given to the eye, when the cloth is
absolutely so flimsy, that it may be torn asunder as easily as a sheet
of writing-paper. Many frauds of this kind are practised.

[Illustration: 1116 1117]

In _fig._ 1116. is given a representation of the position of a fabric of
cloth in section, as it is in the loom before the warp has been closed
upon the woof, which still appears as a straight line. This figure may
usefully illustrate the direction and ratio of contraction which must
unavoidably take place in every kind of cloth, according to the density
of the texture, the dimensions of the threads, and the description of
the cloth. Let A, B, represent one thread of woof completely stretched
by the velocity of the shuttle in passing between the threads of warp
which are represented by the round dots 1, 2, &c., and those
distinguished by 8, 9, &c. When these threads are closed by the
operation of the heddles to form the inner texture, the first tendency
will be to move in the direction 1 _b_, 2 _b_, &c., for those above, and
in that of 8 _a_, 9 _a_, &c., for those below; but the contraction for
A, B, by its deviation from a straight to a curved line, in consequence
of the compression of the warp threads 1 _b_, 2 _b_, &c., and 1 _a_, 2
_a_, &c., in closing, will produce, by the action of the two powers at
right angles to each other, the oblique or diagonal direction denoted by
the lines 1, 8-2, 9, to the left, for the threads above, and that
expressed by the lines 2, 8-3, 9, &c., to the right, for the threads
below. Now, as the whole deviation is produced by the flexure of the
thread A, B, if A is supposed to be placed at the middle of the cloth,
equidistant from the two extremities, or _selvages_ as they are called
by weavers, the thread at 1 may be supposed to move really in the
direction 1 _b_, and all the others to approach to it in the directions
represented, whilst those to the right would approach in the same ratio,
but the line of approximation would be inverted. _Fig._ 1117. represents
that common fabric used for lawns, muslins, and the middle kind of
goods, the excellence of which neither consists in the greatest
strength, nor in the greatest transparency. It is entirely a medium
between _fig._ 1114. and _fig._ 1115.

[Illustration: 1118]

In the efforts to give great strength and thickness to cloth, it will be
obvious that the common mode of weaving, by constant intersection of
warp and woof, although it may be perhaps the best which can be devised
for the former, presents invincible obstructions to the latter, beyond a
certain limit. To remedy this, two modes of weaving are in common use,
which, while they add to the power of compressing a great quantity of
materials in a small compass, possess the additional advantage of
affording much facility for adding ornament to the superficies of the
fabric. The first of these is double cloth, or two webs woven together,
and joined by the operation. This is chiefly used for carpets; and its
geometrical principles are entirely the same as those of plain cloth,
supposing the webs to be sewed together. A section of the cloth will be
found in _fig._ 1118. See CARPET.

[Illustration: 1119]

Of the simplest kind of tweeled fabrics, a section is given in _fig._
1119.

The great and prominent advantage of the tweeled fabric, in point of
texture, arises from the facility with which a very great quantity of
materials may be put closely together. In the figure, the warp is
represented by the dots in the same straight line as in the plain
fabrics; but if we consider the direction and ratio of contraction, upon
principles similar to those laid down in the explanation given of _fig._
1116., we shall readily discover the very different way in which the
tweeled fabric is affected.

When the dotted lines are drawn at _a_, _b_, _c_, _d_, their direction
of contraction, instead of being upon every second or alternate thread,
is only upon every fifth thread, and the natural tendency would
consequently be, to bring the whole into the form represented by the
lines and dotted circles at _a_, _b_, _c_, _d_. In point, then, of
thickness, from the upper to the under superficies, it is evident that
the whole fabric has increased in the ratio of nearly three to one. On
the other hand, it will appear, that four threads or cylinders being
thus put together in one solid mass, might be supposed only one thread,
or like the strands of a rope before it is twisted; but, to remedy this,
the thread being shifted every time, the whole forms a body in which
much aggregate matter is compressed; but where, being less firmly
united, the accession of strength acquired by the accumulation of
materials is partially counteracted by the want of equal firmness of
junction.

[Illustration: 1120]

The second quality of the tweeled fabric, _susceptibility of receiving
ornament_, arises from its capability of being inverted at pleasure, as
in _fig._ 1120. In this figure we have, as before, four threads, and one
alternately intersected; but here the four threads marked 1 and 2 are
under the woof, while those marked 3 and 4 are above.

[Illustration: 1121]

_Fig._ 1121. represents that kind of tweeled work which produces an
ornamental effect, and adds even to the strength of a fabric, in so far
as accumulation of matter can be considered in that light. The figure
represents a piece of velvet cut in section, and of that kind which,
being woven upon a tweeled ground, is known by the name of Genoa velvet.
1st. Because, by combining a great quantity of material in a small
compass, they afford great warmth. 2nd. From the great resistance which
they oppose to external friction, they are very durable. And, 3rd.
Because, from the very nature of the texture, they afford the finest
means of rich ornamental decoration.

The use of velvet cloths in cold weather is a sufficient proof of the
truth of the first. The manufacture of plush, corduroy, and other stuffs
for the dress of those exposed to the accidents of laborious employment,
evinces the second; and the ornamented velvets and Wilton carpeting, are
demonstrative of the third of these positions.

In the figure, the diagonal form which both the warp and woof of cloth
assume, is very apparent from the smallness of the scale. Besides what
this adds to the strength of the cloth, the flushed part, which appears
interwoven at the darkly shaded intervals 1, 2, &c., forms, when
finished, the whole covering or upper surface. The principle, in so far
as regards texture, is entirely the same as any other tweeled fabric.

[Illustration: 1122]

_Fig._ 1122., which represents corduroy, or king’s cord, is merely
striped velvet. The principle is the same, and the figure shows that the
one is a copy of the other. The remaining figures represent those kinds
of work which are of the most flimsy and open description of texture;
those in which neither strength, warmth, nor durability are much
required, and of which openness and transparency are the chief
recommendations.

[Illustration: 1123]

_Fig._ 1123. represents common gauze, or _linau_, a substance very much
used for various purposes. The essential difference between this
description of cloth and all others, consists in the warp being turned
or twisted like a rope during the operation of weaving, and hence it
bears a considerable analogy to _lace_. The twining of gauze is not
continued in the same direction, but is alternately from right to left,
and _vice versâ_, between every intersection of the woof. The fabric of
gauze is always open, flimsy, and transparent; but, from the turning of
the warp, it possesses an uncommon degree of strength and tenacity in
proportion to the quantity of material which it contains. This quality,
together with the transparency of the fabric, renders it peculiarly
adapted for ornamental purposes of various kinds, particularly for
flowering or figuring, either in the loom; or by the needle. In the warp
of gauze; there arises a much greater degree of contraction during the
weaving, than in any other species of cloth; and this is produced by the
turning. The twisting between every intersection of weft amounts
precisely to one complete revolution of both threads; hence this
difference exists between this and every other species of weaving,
namely, that the one thread of warp is always above the woof, and the
contiguous thread is always below.

[Illustration: 1124]

_Fig._ 1124. represents a section of another species of twisted cloth,
which is known by the name of catgut, and which differs from the gauze
only, by being subjected to a greater degree of twine in weaving; for in
place of one revolution between each intersection, a revolution and a
half is always given; and thus the warp is alternately above and below,
as in other kinds of weaving.

[Illustration: 1125]

_Fig._ 1125. is a superficial representation of the most simple kind of
ornamental network produced in the loom. It is called a whip-net by
weavers, who use the term whip for any substance interwoven in cloth for
ornamental purposes, when it is distinct from the ground of the fabric.
In this, the difference is merely in the crossing of the warp; for it is
very evident that the crossings at 1, 2, 3, 4, and 5, are of different
threads from those at 6, 7, 8, and 9.

[Illustration: 1126]

_Fig._ 1126. represents, superficially, what is called the mail-net, and
is merely a combination of common gauze and the whip-net in the same
fabric. The gauze here being in the same direction as the dotted line in
the former figure, the whole fabric is evidently a continued succession
of right-angled triangles, of which the woof forms the basis, the gauze
part the perpendiculars, and the whip part the hypothenuses. The
contraction here being very different, it is necessary that the gauze
and whip parts should be stretched upon separate beams.

[Illustration: 1127]

In order to design ornamental figures upon cloths, the lines which are
drawn from the top to the bottom of the paper may be supposed to
represent the warp; and those drawn across, the woof of the web; any
number of threads being supposed to be included between every two lines.
The paper thus forms a double scale, by which, in the first instance,
the size and form of the pattern may be determined with great precision;
and the whole subsequent operations of the weaver regulated, both in
mounting and working his loom. To enable the projector of a new pattern
to judge properly of its effects, when transferred from the paper to the
cloth, it will be essentially necessary that he should bear constantly
in his view the comparative scale of magnitude which the design will
bear in each, regulating his ideas always by square or superficial
measurement. Thus, in the large design, _fig._ 1127., representing a
bird perched upon the branch of a tree, it will be proper, in the first
place, to count the number of spaces from the point of the bill to the
extremity of the tail; and to render this the more easy, it is to be
observed that every tenth line is drawn considerably bolder than the
others. This number in the design is 135 spaces. Counting again, from
the stem of the branch to the upper part of the bird’s head, he will
find 76 spaces. Between these spaces, therefore, the whole superficial
measure of the pattern is contained. By the measure of the paper, this
may be easily tried with a pair of compasses, and will be found to be
nearly 6-5/10 inches in length, by 3-3/16 inches in breadth. Now, if
this is to be woven in a reed containing 800 intervals in 37 inches, and
if every interval contains five threads, supposed to be contained
between every two parallel lines, the length will be 6·24 inches, and
the breadth 3·52 inches nearly; so that the figure upon the cloth would
be very nearly of the same dimensions as that upon the paper; but if a
1200 reed were used, instead of an 800, the dimensions would be
proportionally contracted.

A correct idea being formed of the design, the weaver may proceed to
mount his loom according to the pattern; and this is done by two
persons, one of whom takes from the design the instructions necessary
for the other to follow in tying his cords.

[Illustration: 1128 1129]

_Fig._ 1128. is a representation of the most simple species of
table-linen, which is merely an imitation of checker-work of various
sizes; and is known in Scotland, where the manufacture is chiefly
practised, by the name of Dornock. When a pattern is formed upon tweeled
cloth, by reversing the flushing, the two sides of the fabric being
dissimilar, one may be supposed to be represented by the black marks,
and the other by the part of the figure which is left uncoloured. For
such a pattern as this, two sets of common tweel-heddles, moved in the
ordinary way, by a double succession of heddles, are sufficient. The
other part of _fig._ 1128. is a design of that intermediate kind of
ornamental work which is called diaper, and which partakes partly of the
nature of the dornock, and partly of that of the damask and tapestry.
The principle upon which all these descriptions of goods are woven is
entirely the same, and the only difference is in the extent of the
design, and the means by which it is executed. _Fig._ 1129. is a design
for a border of a handkerchief or napkin, which may be executed either
in the manner of damask, or as the spotting is practised in the lighter
fabrics.


THENARD’S BLUE, or COBALT BLUE, is prepared by digesting the oxide of
cobalt used in the potteries, with nitric acid, evaporating the nitrate
almost to dryness, diluting it with water, and filtering, to separate
some arseniate of iron, which usually precipitates. The clear liquor is
to be poured into a solution of phosphate of soda, whence an insoluble
phosphate of cobalt falls. This being well washed, is to be intimately
mixed in its soft state with eight times its weight of well-washed
gelatinous alumina, which has been obtained by pouring a solution of
alum into water of ammonia in excess. The uniformly coloured paste is to
be spread upon plates, dried in a stove, then bruised dry in a mortar,
enclosed in a crucible, and subjected to a cherry-red heat for half an
hour. On taking out the crucible, and letting it cool, the fine blue
pigment is to be removed into a bottle, which is to be stoppered till
used.

The arseniate of cobalt may be substituted, in the above process, for
the phosphate, but it must be mixed with sixteen times its weight of the
washed gelatinous alumina. The arseniate is procured by pouring the
dilute nitrate of cobalt into a solution of arseniate of potassa. If
nitrate of cobalt be mixed with the alumina, and the mixture be treated
as above described, a blue pigment will also be obtained, but paler than
the preceding, showing that the colour consists essentially of alumina
stained with oxide of cobalt.


THERMOMETER, signifies the measure of heat. Its description belongs to a
treatise on chemical physics.


THERMOSTAT, is the name of an apparatus for regulating temperature, in
vaporization, distillation, heating baths or hothouses, arid ventilating
apartments, &c.; for which I obtained a patent in the year 1831. It
operates upon the physical principle, that when two thin metallic bars
of different expansibilities are riveted or soldered facewise together,
any change of temperature in them will cause a sensible movement of
flexure in the compound bar, to one side or other; which movement may be
made to operate, by the intervention of levers, &c., in any desired
degree, upon valves, stopcocks, stove-registers, air-ventilators, &c.;
so as to regulate the temperature of the media in which the said
compound bars are placed. Two long rulers, one of steel, and one of hard
hammered brass, riveted together, answer very well; the object being not
simply to _indicate_, but to _control_ or _modify_ temperature. The
following diagrams will illustrate a few out of the numerous
applications of this instrument:--

[Illustration: 1130]

_Fig._ 1130. _a_, _b_, is a single thermostatic bar, consisting of two
or more bars or rulers of differently expansible solids (of which, in
certain cases, wood may be one): these bars or rulers are firmly riveted
or soldered together, face to face. One end of the compound bar is fixed
by bolts at _a_, to the interior of the containing cistern, boiler, or
apartment, _a_, _l_, _m_, _b_, whereof the temperature has to be
regulated, and the other end of the compound bar at _b_, is left free to
move down towards _c_, by the flexure which will take place when its
temperature is raised.

The end _b_, is connected by a link, _b_, _d_, with a lever _d_, _e_,
which is moved by the flexure into the dotted position _b_, _g_, causing
the turning-valve, air-ventilator, or register, _o_, _n_, to revolve
with a corresponding angular motion, whereby the lever will raise the
equipoised slide-damper _k_, _i_, which is suspended by a link from the
end _e_, of the lever _e_, _d_, into the position _k_, _h_. Thus a
hothouse or a water-bath may have its temperature regulated by the
contemporaneous admission of warm, and discharge of cold air, or water.

[Illustration: 1131]

_Fig._ 1131. _a_, _b_, _c_, is a thermostatic hoop, immersed
horizontally beneath the surface of the water-bath of a still. The hoop
is fixed at _a_, and the two ends _b_, _c_, are connected by two links
_b d_, _c d_, with a straight sliding rod _d_, _h_, to which the hoop
will give an endwise motion, when its temperature is altered; _e_; is an
adjusting screw-nut on the rod _d_, _h_, for setting the lever _f_, _g_,
which is fixed on the axis of the turning-valve or cock _f_; at any
desired position, so that the valve may be opened or shut at any desired
temperature, corresponding to the widening of the points _b_, _c_, and
the consentaneous retraction of the point _d_, towards the circumference
_a_, _b_, _c_, of the hoop. _g_, _h_, is an arc graduated by a
thermometer, after the screw-piece _e_ has been adjusted. Through a hole
at _h_, the guide-rod passes. _i_, is the cold-water cistern; _i_, _f_,
_k_, the pipe to admit cold water; _l_, the overflow pipe, at which the
excess of hot water runs off.

[Illustration: 1132]

_Fig._ 1132. shows a pair of thermostatic bars, bolted fast together at
the ends _a_. The free ends _b_, _c_, are of unequal length, so as to
act by the cross links _d_, _f_, on the stopcock _e_. The links are
jointed to the handle of the turning plug of the cock, on opposite
sides of its centre; whereby that plug will be turned round in
proportion to the widening of the points _b_, _c_. _h_, _g_, is the pipe
communicating with the stopcock.

[Illustration: 1133]

Suppose that for certain purposes in pharmacy, dyeing, or any other
chemical art, a water-bath is required to be maintained steadily at a
temperature of 150° F.: let the combined thermostatic bars, hinged
together at _e_, _f_, _fig._ 1133., be placed in the bath, between the
outer and inner vessels _a_, _b_, _c_, _d_, being bolted fast to the
inner vessel at _g_; and have their sliding rod _k_, connected by a link
with a lever fixed upon the turning plug of the stopcock _i_, which
introduces cold water from a cistern _m_, through a pipe _m_, _i_, _n_,
into the bottom part of the bath. The length of the link must be so
adjusted that the flexure of the bars, when they are at a temperature of
150°, will open the said stopcock, and admit cold water to pass into the
bottom of the bath through the pipe _i_, _n_, whereby hot water will be
displaced at the top of the bath through an open overflow-pipe at _q_.
An oil bath may be regulated on the same plan; the hot oil overflowing
from _q_, into a refrigeratory worm, from which it may be restored to
the cistern _m_. When a water bath is heated by the distribution of a
tortuous steam pipe through it, as _i_, _n_, _o_, _p_, it will be
necessary to connect the link of the thermostatic bars with the lever of
the turning plug of the steam-cock, or of the throttle valve _i_, in
order that the bars, by their flexure, may shut or open the steam
passage more or less, according as the temperature of the water in the
bath shall tend more or less to deviate from the pitch to which the
apparatus has been adjusted. The water of the condensed steam will pass
off from the sloping winding-pipe _i_, _n_, _o_, _p_, through the
sloping orifice _p_. A saline, acid, or alkaline bath has a boiling
temperature proportional to its degree of concentration, and may
therefore have its heat regulated by immersing a thermostat in it, and
connecting the working part of the instrument with a stopcock _i_, which
will admit water to dilute the bath whenever by evaporation it has
become concentrated, and has acquired a higher boiling point. The space
for the bath, between the outer and inner pans, should communicate by
one pipe with the water-cistern _m_; and by another pipe, with a safety
cistern _r_, into which the bath may be allowed to overflow during any
sudden excess of ebullition.

[Illustration: 1136]

_Fig._ 1136. is a thermostatic apparatus, composed of three pairs of
bars _d_, _d_, _d_, which are represented in a state of flexure by heat;
but they become nearly straight and parallel when cold, _a_, _b_, _c_,
is a guide rod, fixed at one end by an adjusting screw _e_, in the
strong frame _f_, _e_, having deep guide grooves at the sides. _f_, _g_,
is the working-rod, which moves endways when the bars _d_, _d_, _d_,
operate by heat or cold. A square register-plate _h_, _g_, may be
affixed to the rod _f_, _g_, so as to be moved backwards and forwards
thereby, according to the variations of temperature; or the rod _f_,
_g_, may cause the circular turning air-register _i_, to revolve by rack
and wheel-work, or by a chain and pulley. The register-plate _h_, _g_,
or turning register _i_, is situated at the ceiling or upper part of the
chamber, and serves to let out hot air. _k_, is a pulley, over which a
cord runs to raise or lower a hot-air register _l_, which may be
situated near the floor of the apartment or hothouse, to admit hot air
into the room. _c_, is a milled head, for adjusting the thermostat, by
means of the screw at _e_, in order that it may regulate the temperature
to any degree.

[Illustration: 1137]

_Fig._ 1137. represents a chimney, furnished with a _pyrostat_ _a_, _b_,
_c_, acting by the links _b_, _d_, _e_, _c_, on a damper _f_, _h_, _g_.
The more expansible metal is in the present example supposed to be on
the outside. The plane of the damper-plate will, in this case, be turned
more directly into the passage of the draught through the chimney by
increase of temperature.

[Illustration: 1135]

_Fig._ 1135. represents a circular turning register, such as is used for
a stove, or stove-grate, or for ventilating apartments; it is furnished
with a series of spiral thermostatic bars, each bar being fixed fast at
the circumference of the circle _b_, _c_, of the fixed plate of the
air-register; and all the bars act in concert at the centre _a_, of the
twining part of the register, by their ends being inserted between the
teeth of a small pinion, or by being jointed to the central part of the
turning plate by small pins.

[Illustration: 1134]

_Fig._ 1134. represents another arrangement of my thermostatic apparatus
applied to a circular turning register, like the preceding, for
ventilating apartments. Two pairs of compound bars are applied so as to
act in concert, by means of the links _a c_, _b c_, on the opposite ends
of a short lever, which is fixed on the central part of the turning
plate of the air-register. The two pairs of compound bars _a_, _b_, are
fastened to the circumference of the fixed plate of the turning
register, by two sliding rods _a d_, _b e_, which are furnished with
adjusting screws. Their motion or flexure is transmitted by the links _a
c_, and _b c_, to the turning plate, about its centre, for the purpose
of shutting or opening the ventilating sectorial apertures, more or
less, according to the temperature of the air which surrounds the
thermostatic turning register. By adjusting the screws _a d_, and _b c_,
the turning register is made to close all its apertures at any desired
degree of temperature; but whenever the air is above that temperature,
the flexure of the compound bars will open the apertures.


THIMBLE (_Dé à coudre_, Fr.; _Fingerhut_ (_fingerhat_), Germ.); is a
small truncated metallic cone, deviating little from a cylinder, smooth
within, and symmetrically pitted on the outside with numerous rows of
indentations, which is put upon the tip of the middle finger of the
right hand, to enable it to push the needle readily and safely through
cloth or leather, in the act of sewing. This little instrument is
fashioned in two ways; either with a pitted round end, or without one;
the latter, called the open thimble, being employed by tailors,
upholsterers, and, generally speaking, by _needle-men_. The following
ingenious process for making this essential implement, the contrivance
of M. M. Rouy and Berthier, of Paris, has been much celebrated, and very
successful. Sheet-iron, one twenty-fourth of an inch thick, is cut into
strips, of dimensions suited to the intended size of the thimbles. These
strips are passed under a punch-press, whereby they are cut into discs
of about 2 inches diameter, tagged together by a tail. Each strip
contains one dozen of these blanks. A child is employed to make them
red-hot, and to lay them on a mandril nicely fitted to their size. The
workman now strikes the middle of each with a round-faced punch, about
the thickness of his finger, and thus sinks it into the concavity of the
first mandril. He then transfers it successively to another mandril,
which has five hollows of successively increasing depth; and, by
striking it into them, brings it to the proper shape.

A second workman takes this rude thimble, sticks it in the chuck of his
lathe, in order to polish it within, then turns it outside, marks the
circles for the gold ornament, and indents the pits most cleverly with a
kind of milling tool. The thimbles are next annealed, brightened, and
gilt inside, with a very thin cone of gold leaf, which is firmly united
to the surface of the iron, simply by the strong pressure of a smooth
steel mandril. A gold fillet is applied to the outside, in an annular
space turned to receive it, being fixed, by pressure at the edges, into
a minute groove formed on the lathe.

Thimbles are made in this country by means of moulds in the
stamping-machine. See STAMPING OF METALS.


THORINA, is a primitive earth, with a metallic basis, discovered in
1828, by Berzelius. It was extracted from the mineral _thorite_, of
which it constitutes 58 per cent., and where it is associated with the
oxides of iron, lead, manganese, tin, and uranium, besides earths and
alkalis, in all 12 substances. Pure thorina is a white powder, without
taste, smell, or alkaline reaction on litmus. When dried and calcined,
it is not affected by either the nitric or muriatic acid. It may be
fused with borax into a transparent glass, but not with potash or soda.
Fresh precipitated thorina is a hydrate, which dissolves readily in the
above acids, as well as in solutions of the carbonates of potash, soda,
and ammonia, but not in these alkalis in a pure state. This earth
consists of 74·5 parts of the metal _thorinum_, combined with 100 of
oxygen. Its hydrate contains one equivalent prime of water. It is
hitherto merely a chemical curiosity, remarkable chiefly for a density
of 9·402, far greater than that of all the earths, and even of copper.

[Illustration: 1138]


THREAD MANUFACTURE. The doubling and twisting of cotton or linen yarn
into a compact thread, for weaving bobbin-net, or for sewing garments,
is performed by a machine resembling the throstle of the cotton-spinner.
_Fig._ 1138. shows the thread-frame in a transverse section,
perpendicular to its length. _a_, is the strong framing of cast iron;
_b_, is the _creel_, or shelf, in which the bobbins of yarn _l_, _l_,
are set loosely upon their respective skewers, along the whole line of
the machine, their lower ends turning in oiled steps, and their upper in
wire eyes; _c_, is a glass rod, across which the yarn runs as it is
unwound; _d_, _d_, are oblong narrow troughs, lined with lead, and
filled with water, for moistening the thread during its torsion; the
threads being made to pass through eyes at the bottom of the fork _e_,
which has an upright stem for lifting it out, without wetting the
fingers, when any thing goes amiss; _f_, _f_, are the pressing rollers,
the under one _g_, being of smooth iron, and the upper one _h_, of
box-wood; the former extends from end to end of the frame, in lengths
comprehending 18 threads, which are joined by square pieces, as in the
drawing-rollers of the mule-jenny. The necks of the under rollers are
supported, at the ends and the middle, by the standards _i_, secured to
square bases _j_, both made of cast iron. The upper cylinder has an iron
axis, and is formed of as many rollers as there are threads; each roller
being kept in its place upon the lower one by the guides _k_, whose
vertical slots receive the ends of the axes.

The yarn delivered by the bobbin _l_, glides over the rod _c_, and
descends into the trough _d_, _e_, where it gets wetted; on emerging, it
goes along the bottom of the roller _g_, turns up, so as to pass between
it and _h_, then turns round the top of _h_, and finally proceeds
obliquely downwards, to be wound upon the bobbin _m_, after traversing
the guide-eye _n_. These guides are fixed to the end of a plate, which
may be turned up by a hinge-joint at _o_, to make room for the bobbins
to be changed.

There are three distinct simultaneous movements to be considered in this
machine: 1. that of the rollers, or rather of the under roller, for the
upper one revolves merely by friction; 2. that of the spindles _m_,
_s´_; 3. the up-and-down motion of the bobbins upon the spindles.

The first of these motions is produced by means of toothed wheels, upon
the right hand of the under set of rollers. The second motion, that of
the spindles, is effected by the drum _z_, which extends the whole
length of the frame, turning upon the shaft _v_, and communicating its
rotatory movement (derived from the steam pulley) to the whorl _b´_, of
the spindles, by means of the endless band or cord _a´_. Each of these
cords turns four spindles, two upon each side of the frame. They are
kept in a proper state of tension by the weights _c´_, which act
tangentially upon the circular arc _d´_, fixed to the extremity of the
bell-crank lever _e´ f´ g´_, and draw in a horizontal direction the
tension pulleys _h_, embraced by the cords. The third movement, or the
vertical traverse of the bobbins, along the spindles _m_, takes place as
follows:--

The end of one of the under rollers carries a pinion, which takes into a
carrier wheel, that communicates motion to a pinion upon the extremity
of the shaft _m´_, of the heart-shaped pulley _n´_. As this eccentric
revolves, it gives a reciprocating motion to the levers _o´_, _o´_,
which oscillate in a vertical plane round the points, _p´_, _p´_. The
extremities of these levers, on either side, act by means of the links
_q´_, upon the arms of the sliding sockets _r´_, and cause the vertical
rod _s´_, to slide up and down in guide-holes at _t´_, _u´_, along with
the cast-iron step _v´_, which bears the bottom washer of the bobbins.
The periphery of the heart-wheel _n´_, is seen to bear upon friction
wheels _x_, _x´_, set in frames adjusted by screws upon the lower end of
the bent levers, at such a distance from the point _p´_, as that the
traverse of the bobbins may be equal to the length of their barrel.

By adapting change pinions and their corresponding wheels to the
rollers, the delivery of the yarn may be increased or diminished in any
degree, so as to vary the degree of twist put into it by the uniform
rotation of the drum and spindles. The heart motion being derived from
that of the rollers, will necessarily vary with it.

Silk thread is commonly twisted in lengths of from 50 to 100 feet, with
hand reels, somewhat similar to those employed for making ropes by hand.


TILES. See BRICKS.


TILTING OF STEEL. See STEEL. Rees’s Cyclopædia contains an excellent
article on this subject.


TIN (_Etain_, Fr.; _Zinn_, Germ.); in its pure state, has nearly the
colour and lustre of silver. In hardness it is intermediate between gold
and lead; it is very malleable, and may be laminated into foil less than
the thousandth of an inch in thickness; it has an unpleasant taste, and
exhales on friction a peculiar odour; it is flexible in rods or straps
of considerable strength, and emits in the act of bending a crackling
sound, as if sandy particles were intermixed, called the creaking of
tin. A small quantity of lead, or other metal, deprives it of this
characteristic quality. Tin melts at 442° Fahr., and is very fixed in
the fire at higher heats. Its specific gravity is 7·29. When heated to
redness with free access of air, it absorbs oxygen with rapidity, and
changes first into a pulverulent gray protoxide, and by longer ignition,
into a yellow-white powder, called _putty_ of tin. This is the peroxide,
consisting of 100 of metal + 27·2 of oxygen.

Tin has been known from the most remote antiquity; being mentioned in
the books of Moses. The Phœnicians carried on a lucrative trade in it
with Spain and Cornwall.

There are only two ores of tin; the peroxide, or tin-stone, and tin
pyrites; the former of which alone has been found in sufficient
abundance for metallurgic purposes. The external aspect of tin-stone has
nothing very remarkable. It occurs sometimes in twin crystals; its
lustre is adamantine; its colours are very various, as white, gray,
yellow, red, brown, black; specific gravity 6·9 at least; which is,
perhaps, its most striking feature. It does not melt by itself before
the blowpipe; but is reducible in the smoky flame or on charcoal. It is
insoluble in acids. It has somewhat of a greasy aspect; and strikes fire
with steel.

Tin-stone occurs disseminated in the antient rocks, particularly
granite; also in beds and veins, in large irregular masses, called
_stockwerks_; and in pebbles, an assemblage of which is called
stream-works, where it occasionally takes a ligneous aspect, and is
termed _wood-tin_.

This ore has been found in few countries in a workable quantity. Its
principal localities are, Cornwall, Bohemia, Saxony, in Europe; and
Malacca and Banca, in Asia. The tin-mines of the Malay peninsula lie
between the 10th and 6th degree of south latitude; and are most
productive in the island of Junck-Ceylon, where they yield sometimes 800
tons per annum, which are sold at the rate of 48_l._ each. The ores are
found in large caves near the surface; and though actively mined for
many centuries, still there is easy access to the unexhausted parts. The
mines in the island of Banca, to the east of Sumatra, discovered in
1710, are said to have furnished, in some years, nearly 3500 tons of
tin. Small quantities occur in Gallicia in Spain, in the department of
Haute Vienne in France, and in the mountain chains of the Fichtel and
Riesengebürge in Germany. The columnar pieces of pyramidal tin-ore from
Mexico and Chile, are products of stream-works. Small groups of black
twin crystals have been lately discovered in the albite rock of
Chesterfield in Massachusetts.

The Cornish ores occur--1. in small strata or veins, or in masses; 2. in
stockwerks, or congeries of small veins; 3. in large veins; 4.
disseminated in alluvial deposits.

The stanniferous small veins, or thin flat masses, though of small
extent, are sometimes very numerous, interposed between certain rocks,
parallel to their beds, and are commonly called tin-floors. The same
name is occasionally given to stockwerks. In the mine of Bottalack, a
_tin-floor_ has been found in the killas (primitive schistose rock),
thirty-six fathoms below the level of the sea; it is about a foot and a
half thick, and occupies the space between a principal vein and its
ramification; but there seems to be no connexion between the _floor_ and
the great vein.

2. Stockwerks occur in granite and in the felspar porphyry, called in
Cornwall, _elvan_. The most remarkable of these in the granite, is at
the tin-mine of Carclase, near _St. Austle_. The works are carried on in
the open air, in a friable granite, containing felspar disintegrated
into _kaolin_, or china clay, which is traversed by a great many small
veins, composed of tourmaline, quartz, and a little tin-stone, that form
black delineations on the face of the light-gray granite. The thickness
of these little veins rarely exceeds 6 inches, including the adhering
solidified granite, and is occasionally much less. Some of them run
nearly east and west, with an almost vertical dip; others, with the same
direction, incline to the south at an angle with the horizon of 70
degrees.

Stanniferous stockwerks are much more frequent in the elvan (porphyry);
of which the mine of Trewidden-ball is a remarkable example. It is
worked among flattened masses of _elvan_, separated by strata of
_killas_, which dip to the east-north-east at a considerable angle. The
tin ore occurs in small veins, varying in thickness from half an inch to
8 or 9 inches, which are irregular, and so much interrupted, that it is
difficult to determine either their direction or their inclination.

3. The large and proper metalliferous veins are not equally distributed
over the surface of Cornwall and the adjoining part of Devonshire; but
are grouped into three districts; namely, 1. In the south-west of
Cornwall, beyond Truro; 2. In the neighbourhood of St. Austle; and 3. In
the neighbourhood of Tavistock in Devonshire.

The first group is by far the richest, and the best explored. The
formation most abundant in tin mines is principally granitic; whilst
that of the copper mines is most frequently schistose or killas; though
with numerous exceptions. The great tin veins are the most antient
metalliferous veins in Cornwall; yet they are not all of one formation,
but belong to two different systems. Their direction is, however, nearly
the same, but some of them dip towards the north, and others towards the
south. The first are older than the second; for in all the mines where
these two sets of veins are associated, the one which dips to the north,
cuts across and throws out the one which dips to the south. See MINES,
p. 835.

[Illustration: 1139]

At Trevannance mines, the two systems of tin veins are both intersected
by the oldest of the copper veins; indicating the prior existence of the
tin veins. In _fig._ 1139. _b_, marks the first system of tin veins;
_c_, the second; and _d_, the east and west copper veins. Some of these
tin veins, as at Poldice, have been traced over an extent of two miles;
and they vary in thickness from a small fraction of an inch to several
feet, the average width being from 2 to 4 feet; though this does not
continue uniform for any length, as these veins are subject to continual
narrowings and expansions. The gangue is quartz, chlorite, tourmaline,
and sometimes decomposed granite and fluor spar.

4. _Alluvial tin ore, stream tin._--Peroxide of tin occurs disseminated
both in the _alluvium_ which covers the gentle slopes of the hills
adjoining the rich tin-mines, and also in the alluvium which fills the
valleys that wind round their base; but in these numerous deposits the
tin-stone is rarely distributed in sufficient quantities to make it
worth the working. The most important explorations of _alluvial tin ore_
are grouped in the environs of St. Just and St. Austle; where they are
called _stream-works_; because water is the principal agent employed to
separate the metallic oxide from the sand and gravel.

[Illustration: 1140]

The tin mine of Altenberg, in Saxony (_fig._ 1140., which is a vertical
projection in a plane passing from west to east,) is remarkable for a
stockwerke, or interlaced mass of ramifying veins, which has been worked
ever since the year 1458. The including rock is a primitive porphyry,
superposed upon gneiss; becoming very quartzose as it approaches the
lode. This is usually disseminated in minute particles, and accompanied
with wolfram, copper and arsenical pyrites, _fer oligiste_, sulphuret of
molybdenum, and bismuth, having gangues of lithomarge, fluor spar, mica,
and felspar. The space which the ore occupies in the heart of the
quartz, is a kind of dædalus, the former being often so dispersed among
the latter as to seem to merge into it; whence it is called by the
workmen _zwitter_, or _ambiguous_. In 1620, the mine was worked by 21
independent companies, in a most irregular manner, whereby it was
damaged to a depth of 170 fathoms by a dreadful downfall of the roofs.
This happened on a Sunday, providentially, when the pious miners were
all at church. The depth of this abyss, marked by the curved line _b_,
_b_, _b_, is 66 fathoms; but the devastation is manifest to a depth of
95 fathoms below that curve, and 35 fathoms below the actual workings,
represented at the bottom of the shaft under B. The parts excavated are
shaded black in the figure. There are two masses of ore, one under the
shaft B, and another under the shaft C; which at the levels 5 and 10 are
in communication, but not at 6, 7. There is a direct descent from 8 to
9. The deposits are by no means in one vertical plane, but at a
considerable horizontal distance from each other. A is the descending
shaft; B is the extraction shaft, near the mouth of which there is a
water-wheel; C is another extraction shaft, worked also by means of a
water-wheel. A and C are furnished with ladders, but for B the ladders
are placed in an accessory shaft _b´_; under D, a shaft is sunk for
pumping out the water, by means of an hydraulic wheel at D; E is the
gallery or drift for admitting the water which drives the wheels. This
falls 300 feet, and ought to be applied to a water-pressure engine,
instead of the paddles of a wheel. At D, is the gallery of discharge for
the waters, which serves also to ventilate the mine, being cut to the
day, through 936 toises of syenitic porphyry and gneiss. J, is a great
vaulted excavation. The mine has 13 stages of galleries, of which 11
serve for extracting the ore; 1 is the mill-course; the rest are marked
with the numbers 2, 3, 4, &c.; each having besides a characteristic
German name. The rare mineral called _topaz pycnite_ is found in this
mine, above 10, between the shafts C and D.

The only rule observed in taking ore from this mine, has been to work as
much out of each of these levels as is possible, without endangering the
superincumbent or collateral galleries; on which account many pillars
are constructed to support the roofs. The mine yields annually 1600
quintals (Leipzick) of tin, being four-fifths of the whole furnished by
the district of Altenberg; to produce which, 400,000 quintals of ore are
raised. 1000 parts of the rock yield 8 of concentrated schlich,
equivalent to only 4 of metal; being only 1 in 250 parts.

But the most extensive and productive stream-works, are those of
Pentowan, near St. Austle.

[Illustration: 1141]

_Fig._ 1141. represents a vertical section of the Pentowan mine, taken
from the _stream-work_, _Happy Union_. A vast excavation, R, T, U, S,
has been hollowed out in the open air, in quest of the alluvial tin ore
T, which occurs here at an unusual depth, below the level of the strata
R, S. Before getting at this deposit, several successive layers had to
be sunk through; namely, 1, 2, 3; the gravel, containing in its middle a
band of ochreous earth 2, or ferruginous clay; 4, a black peat,
perfectly combustible, of a coarse texture, composed of reeds and woody
fibres, cemented into a mass by a fine loam; 5, coarse sea-sand, mingled
with marine shells; 6, a blackish marine mud, filled with shells. Below
these the deposit of tin-stone occurs, including fragments of various
size, of clay slate, flinty slate, quartz, iron ore, jasper; in a word,
of all the rocks and gangues to be met with in the surrounding
territory, with the exception of granite. Among these fragments there
occur, in rounded particles, a coarse quartzose sand, and the tin-stone,
commonly in small grains and crystals. Beneath the bed T, the clay slate
occurs, called _killas_ (A, X, Y), which supports all the deposits of
more recent formation.

The system of mining is very simple. The successive beds, whose
thickness is shown in the figure, are visibly cut out into steps or
platforms. By a level or gallery of efflux _k_, the waters flow into the
bottom of the well _l_, _m_, which contains the drainage pumps; and
these are put in action by a machine _j_, moved by a water-wheel. The
extraction of the ore is effected by an inclined plane _i_, cut out of
one of the sides of the excavation, at an angle of about 45 degrees. At
the lower end of this sloping pathway there is a place of loading; and
at its upper end _h_, a horse-gin, for alternately raising and lowering
the two baskets of extraction on the pathway _i_.

_Mine tin_ requires peculiar care in its mechanical preparation or
dressing, on account of the presence of foreign metals, from which, as
we have stated, the stream tin is free.

1. As the mine tin is for the most part extremely dispersed through the
gangue, it must be all stamped and reduced to a very fine powder, to
allow the metallic particles to be separated from the stony matters.

2. As the density of tin-stone is much greater than that of most other
metallic ores, it is less apt to run off in the washing; and may,
therefore, be dressed so as to be completely stripped of every matter
not chemically combined.

3. As the peroxide of tin is not affected by a moderate heat, it may be
exposed to calcination; whereby the specific gravity of the associated
sulphurets and arseniurets is so diminished as to facilitate their
separation.

We may therefore conclude, that tin ore should be first of all pounded
very fine in the stamp-mill, then subjected to reiterated washings, and
afterwards calcined. The order of proceeding in Cornwall is as
follows:--

1. _Cleaning the ore._--This is usually done at the mouth of the gallery
of efflux, by agitating the ore in the stream of water as it runs out.
Sometimes the ore is laid on a grating, under a fall of water.

2. _Sorting._--The ore thus cleaned, is sorted on the grate, into four
heaps: 1. stones rich in tin; 2. stones containing both tin and copper
ore; 3. copper ore; 4. sterile pieces, composed in a great measure of
stony gangue, with iron and arsenical pyrites. In those veins where
there is no copper ore, the second and third heaps are obviously absent.
When present, the compound ore is broken into smaller pieces with a
mallet, and the fragments are sorted anew.

3. _Stamping._--The stanniferous fragments (No. 1.) are stamped into a
sand, of greater or less fineness, according to the dissemination of the
tin-stone in the gangue. The determination of the size of the sand, is
an object of great importance. It is regulated by a copper plate pierced
with small holes, through which every thing from the stamping-mill must
run off with the rapid stream introduced for this purpose. This plate
forms the front of the stamp cistern.

Several years ago, all the stamp mills were driven by water-wheels,
which limited the quantity of ore that could be worked to the hydraulic
power of the stream or waterfall; but since the steam engine has been
applied to this purpose, the annual product of tin has been greatly
increased. On the mine of Huel Vor, there are three steam engines
appropriated to the stamping-mills. Their force is 25 horses at least.
One of these machines, called _south stamps_, drives 48 pestles; a
second, called _old stamps_, drives 36; and a third, 24. The weight of
these pestles varies from 370 to 387 pounds; and they generally rise
through a space of 10-1/2 inches. The machine called _south stamps_, the
strongest of the three, gives 17-1/2 blows in the minute, each pestle
being lifted twice for every stroke of the piston. The steam engine of
this mill has a power of 25 horses, and it consumes 1062 bushels of
coals in the month. Three pestles constitute a battery, or stamp-box.

[Illustration: 1142]

_Washing and stamping of tin ores at Polgooth, near St. Austle._--The
stamps or pestles are of wood, 6 inches by 5-1/2 in the square: they
carry lifting bars _b_, secured with a wooden wedge and a bolt of iron,
and they terminate below in a lump of cast iron A, called the head,
which is fastened to them by a tail, and weighs about 2-1/2 cwts. The
shank of the pestle is strengthened with iron hoops. A turning-shaft
communicates motion to the stamps by cams stuck round its circumference,
so arranged that the second falls while the first and third of each set
are uplifted. There are 4 cams on one periphery, and the shaft makes 7
turns in the minute. Each stamp, therefore, gives 28 strokes per minute,
and falls through a space of 7-1/2 inches. The stamp chest is open
behind, so that the ore slips away under the pestles, by its weight,
along the inclined plane with the stream of water. The bottom of the
troughs consists of stamped ores. With 6 batteries of 6 pestles each, at
Poldice, near Redruth, 120 bags of ore are stamped in 12 hours; each bag
containing 18 gallons of 282 cubic inches; measuring altogether 352
cubic feet, and 864 cubic inches.

[Illustration: 1143 1144 1145 1146]

The openings in the front sides of the troughs are nearly 8 inches by
7-1/2: they are fitted with an iron frame, which is closed with sheet
iron, pierced with about 160 holes in the square inch, bored conically,
being narrower within. The ore, on issuing, deposits its _rough_ in the
first basin, and its slimes in the following basins. The rough is washed
in _buddles_ (see LEAD, page 751), and in _tossing tubs_; the slimes in
_trunks_, and upon a kind of twin tables, called _racks_. Into the
_tossing-tub_, or _dolly_, _fig._ 1143., the stamped ore is thrown,
along with a certain quantity of water, and a workman stirs it about
with an iron shovel for three or four minutes. He then removes a little
of the water with a handled pitcher, and strikes the sides of the tub
for 8 or 10 minutes with a hammer, which hastens the subsidence of the
denser parts. The water is next poured off by inclining the tub to one
side. In one operation of this kind, four distinct strata of the ores
may be procured, as indicated by the lines _a b_, _c d_, _e f g_, _h i
k_, in the figure. The portion A is to be washed again in the
_trunking-box_, _figs._ 1144, 1145.; B is to be washed upon the German
chests or racks, _fig._ 1146.; C, the most considerable, is put aside,
as schlich fit for the market; D, forming a nucleus the centre of the
tub, is to be passed through sieves of copper wire, having 18 meshes in
the square inch. This product thus affords a portion D´, which passes
through the sieve, and D´´ which remains upon it; the latter is
sometimes thrown away, and at others is subjected to the operation
called the _tie_, viz., a washing upon the sloping bottom of a long
trough.

The slimes are freed from the lighter mud in the trunking-box, _figs._
1144, 1145.; which is from 7 to 8 feet long. Being accumulated at M, the
workman pushes them back with a shovel from _a_ towards _b_. The
metallic portion is carried off, and deposited by the stream of water
upon the table; but the earthy matters are floated along into a basin
beyond it. The product collected in the chest is divided into two
portions; the one of which is washed once, and the other twice, upon the
_rack_, _fig._ 1146. This is composed of a frame C, which carries a
sloping board or table, susceptible of turning round to the right or
left upon two pivots, K, K. The head of the table is the inclined plane
T. A small board P, which is attached by a band of leather L, forms the
communication with the lower table C, whose slope is generally 5 inches
in its whole length of 9 feet; but this may vary with the nature of the
ore, being somewhat less when it is finely pulverized. The ore is thrown
upon T, in small portions of 20 or 25 lbs. A woman spreads it with a
rake, while a stream of water sweeps a part of it upon the table, where
it gets washed. The fine mud falls through a cross slit near the lower
end, into a basin B. After working for a few minutes, should the schlich
seem tolerably rich, the operative turns the table round its axis K, K,
so as to tumble it into the boxes below. The mud is in B; an impure
schlich in B´, which must be washed again upon the _rack_; and a schlich
fit for roasting in B´´.

The slope of the rack-table for washing the _roasted_ tin ore, is 7-3/4
inches in the 9 feet.

[Illustration: 1147]

_Crushing rolls at the Pembroke mines._--Waggons, moved on a railway by
an endless rope, bring the ore to be crushed, immediately over the
rolls, as shown in _fig._ 1147. A trap being opened in the side of the
waggon, the ore falls into the hopper T, whence it passes directly
between the twin cylinders C, C, and next upon the sieve D, which
receives a seesaw motion horizontally, by means of the rod L, and the
crank of the upright turning-shaft. The finer portion of ore, which
passes through that sieve, forms the heap S. The coarser portion is
tossed over the edge of the sieve, and falls between the cylinders C´
C´, upon a lower level, and forms the second heap S´ of sifted, and S´´
of unsifted, ore.

The holes of the sieves D, D´, being of the same size, the products S,
S´, are of the same fineness. S´´ is ground again, being mixed, in the
uppermost hopper T, along with the lumps from the waggons.

[Illustration: 1148]

The diameter and length of the under rolls (see _fig._ 1148.) are each
16 inches. _a b_, is the square end of the gudgeon _t_, which prevents
the shaft shifting laterally out of its place. The diameter of the upper
rolls is 18 inches, but their length is the same. Both are made of white
cast iron, _chilled_ or case-hardened by being cast in iron moulds
instead of sand; and they last a month, at least, when of good quality.
They make from 10 to 15 turns in a minute, according to the hardness of
the ores of tin or copper; and can grind about 50 tons of rich copper
ore in 12 hours; but less of the poorer sort.

The next process is the calcination in the _burning-house_; which
includes several reverberatory furnaces. At the mine of Poldice, they
are 4 or 5 yards long, by from 2-1/2 to 3 yards wide. Their hearth is
horizontal; the elevation, about 26 inches high near the fireplace,
sinks slightly towards the chimney. There is but one opening, which is
in the front; it is closed by a plate-iron door, turning on hinges.
Above the door there is a chimney, to let the sulphureous and arsenical
vapours fly off, which escape out of the hearth, without annoying the
workmen. This chimney leads to horizontal flues, in which the arsenious
acid is condensed.

Six hundred weight of ore are introduced; the calcination of which takes
from 12 to 18 hours, according to the quantity of pyrites contained in
the ore. At the beginning of the operation, a moderate heat is applied,
after which it is pushed to a dull red, and kept so during several
hours. The door is shut; the materials are stirred from time to time
with an iron rake, to expose new surfaces, and prevent them from
agglutinating or _kerning_, as the workmen say. The more pyrites is
present, the more turning is necessary. Should the ore contain black
oxide of iron, it becomes peroxidized, and is then easily removed by a
subsequent washing.

[Illustration: 1149 1150]

_Figs._ 1149, 1150. represent the furnace employed at Altenberg, in
Saxony, for roasting tin ores. _a_ is the grate; _b_, the sole of the
roasting hearth; _c_, an opening in the arched roof for introducing the
dried schlich (the ground and elutriated ore); _d_, is the smoke-mantle
or chimney-hood, at the end of the furnace, under which the workmen turn
over the spread schlich, with long iron rods bent at their ends; _e_, is
the poison vent, which conducts the arsenical vapours to the poison
chamber (_gifthaus_) of condensation.

When the ore is sufficiently calcined, as is shown by its ceasing to
exhale vapours, it is taken out, and exposed for some days to the action
of the air, which decomposes the sulphurets, or changes them into
sulphates. The ore is next put into a tub filled with water, stirred up
with a wooden rake, and left to settle; by which means the sulphate of
copper that may have been formed, is dissolved out. After some time,
this water is drawn off into a large tank, and its copper recovered by
precipitation with pieces of old iron. In this way, almost all the
copper contained in the tin ore is extracted.

The calcined ore is sifted, and treated again on the racks, as above
described. The pure schlich, called _black tin_, is sold under this name
to the smelters; and that which collects on the middle part of the
inclined wash-tables, being much mixed with wolfram, is called _mock
lead_. This is passed once more through the stamps, and washed; when it
also is sold as _black tin_.

Stream tin is dressed by similar methods: 1. by washing in a
trunking-box, of such dimensions that the workman stands upon it in
thick boots, and makes a skilful use of the rake; 2. by separating the
larger conglomerate pebbles from the smaller pure ones; picking,
stamping, and washing, on a kind of _sleeping-tables_. See METALLURGY,
_figs._ 677, 678.

The tin ores of Cornwall and Devonshire are all reduced within the
counties where they are mined, as the laws prohibit their exportation
out of them. Private interests suffer no injury from this prohibition;
because the vessels which bring the fuel from Wales, for smelting these
ores, return to Swansea and Neath loaded with copper ores.

The smelting-works belong in general to individuals who possess no tin
mines, but who purchase at the cheapest rate the ores from the mining
proprietors. The ores are appraised according to their contents in
metal, and its fineness; conditions which they determine by the
following mode of assay. When a certain number of bags of ore, of nearly
the same quality, are brought to the works, a small sample is taken from
each bag, and the whole are well blended. Two ounces of this average ore
are mixed with about 4 per cent. of ground coal, put into an open
earthen crucible, and heated in an air furnace (in area about 10 inches
square) till reduction takes place. As the furnace is very hot when the
crucible is introduced, the assay is finished in about a quarter of an
hour. The metal thus revived, is poured into a mould, and what remains
in the crucible is pounded in a mortar, that the grains of tin may be
added to the ingot.

This method, though imperfect in a chemical point of view, serves the
smelter’s purpose, as it affords him a similar result to what he would
get on the great scale. A more exact assay would be obtained by fusing,
in a crucible lined with hard-rammed charcoal, the ore mixed with 5 per
cent. of ground glass of borax. To the crucible a gentle heat should be
applied during the first hour, then a strong heat during the second
hour, and, lastly, an intense heat for a quarter of an hour. This
process brings out from 4 to 5 per cent. more tin than the other; but it
has the inconvenience of reducing the iron, should any be present; which
by subsequent solution in nitric acid will be readily shown. This assay
would be too tedious for the smelter, who may have occasion to try a
great many samples in one day.

The smelting of tin ores is effected by two different methods:--

In the first, a mixture of the ore with charcoal is exposed to heat on
the hearth of a reverberatory furnace fired with coal.

In the second, the tin ore is fused in a blast furnace, called a
blowing-house, supplied with wood charcoal. This method is practised in
only a few works, in order to obtain a very pure quality of tin, called
_grain tin_ in England, and _étain en larmes_ in France; a metal
required for certain arts, as dyeing, &c. This method is applied merely
to stream tin.

In the _smelting-houses_, where the tin is worked in reverberatories,
two kinds of furnaces are employed; the reduction and the refining
furnaces.

[Illustration: 1151 1152]

_Figs._ 1151, 1152. represent the furnaces for smelting tin at St.
Austle, in Cornwall; the former being a longitudinal section, the latter
a ground plan, _a_ is the fire-door, through which pitcoal is laid upon
the grate _b_; _c_ is the fire-bridge; _d_, the door for introducing the
ore; _e_, the door through which the ore is worked upon the hearth _f_;
_g_, the stoke-hole; _h_, an aperture in the vault or roof, which is
opened at the discharge of the waste schlich, to secure the free escape
of the fumes up the chimney; _i_, _i_, air channels, for admitting cold
air under the fire-bridge and the sole of the hearth, with the view of
protecting them from injury by the intensity of the heat above. _k_,
_k_, are basins into which the melted tin is drawn off; _l_, the flue;
_m_, the chimney, from 35 to 50 feet high. The roasted and washed
schlich is mixed with small coal or culm, along with a little slaked
lime, or fluor spar, as a flux; each charge of ore amounts to from 15 to
24 cwt., and contains from 60 to 70 per cent. of metal.

[Illustration: 1153 1154]

_Fig._ 1153. represents in a vertical section through the tuyère, and
_fig._ 1154. in a horizontal section, in the dotted line _x_, _x_, of
_fig._ 1153., the furnace employed for smelting tin at the Erzgebirge
mines, in Saxony. _a_, are the furnace pillars, of gneiss; _b_, _b_, are
shrouding or casing walls; _c_, the tuyère wall; _d_, front wall, both
of granite; as also the tuyère _e_. _f_, the sole-stone, of granite,
hewn out basin-shaped; _g_, the _eye_, through which the tin and slag
are drawn off into the fore-hearth _h_; _i_, the stoke-hearth; _k_, _k_,
the light ash chambers; _l_, the arch of the tuyère; _m_, _m_, the
common flue, which is placed under the furnace and the hearths, and has
its outlet under the vault of the tuyère.

In the smelting furnaces at Geyer the following dimensions are
preferred:--Length of the tuyère wall, 11 inches; of the breast wall, 11
inches; depth of the furnace, 17 inches. High chimney-stalks are
advantageous where a great quantity of ores is to be reduced, but not
otherwise.

The _refining furnaces_ are similar to those which serve for reducing
the ore; only, instead of a basin of reception, they have a refining
basin placed alongside, into which the tin is run. This basin is about 4
feet in diameter, and 32 inches deep; it consists of an iron pan, placed
over a grate, in which a fire may be kindled. Above this pan there is a
turning gib, by means of which a billet of wood may be thrust down into
the bath of metal, and kept there by wheeling the gibbet over it,
lowering a rod, and fixing it in that position.

The works in which the blast furnaces are employed, are called
_blowing-houses_. The smelting furnaces are 6 feet high, from the bottom
of the crucible (concave hearth) to the throat, which is placed at the
origin of a long and narrow chimney, interrupted by a chamber, where the
metallic dust, carried off by the blast, is deposited. This chamber is
not placed vertically over the furnace; but the lower portion of the
chimney has an oblique direction from it. The furnace is lined with an
upright cylinder of cast iron, coated internally with loam, with an
opening in it for the blast. This opening, which corresponds to the
lateral face opposite to the charging side, receives a _tuyère_, in
which the nozzles of two cylinder single bellows, driven by a
water-wheel, are planted. The _tuyère_ opens at a small height above the
sole of the furnace. On a level with the sole, the iron cylinder
presents a slope, below which is the hemispherical basin of reception,
set partly beneath the interior space of the furnace, and partly
without. Near the corner of the building there is a second basin of
reception, larger than the first, which can discharge itself into the
former by a sloping gutter. Near this basin there is another, for the
refining operation. These are all made either of brick or cast iron.

The quality of the average ground-tin ore prepared for smelting is such,
that 20 parts of it yield from 12-1/2 to 13 of metallic tin, (62-1/2 to
65 per cent.) The treatment consists of two operations, _smelting_ and
_refining_.

_First operation; deoxidization of the ore, and fusion of the
tin._--Before throwing the ore into the smelting furnace, it is mixed
with from one-fifth to one-eighth of its weight of _blind coal_, in
powder, called _culm_; and a little slaked lime is sometimes added, to
render the ore more fusible. These matters are carefully blended, and
damped with water, to render the charging easier, and to prevent the
blast from sweeping any of it away at the commencement. From 12 to 16
cwt. are introduced at a charge; and the doors are immediately closed
and luted, while the heat is progressively raised. Were the fire too
strong at first, the tin oxide would unite with the quartz of the
gangue, and form an enamel. The heat is applied for 6 or 8 hours, during
which the doors are not opened; of course the materials are not stirred.
By this time the reduction is, in general, finished; the door of the
furnace is removed, and the melted mass is worked up to complete the
separation of the tin from the scoriæ, and to ascertain if the operation
be in sufficient forwardness. When the reduction seems to be finished,
the scoriæ are taken out at the same door, with an iron rake, and
divided into three sorts; those of the first class A, which constitute
at least three-fourths of the whole, are as poor as possible, and may be
thrown away; the scoriæ of the second class B, which contain some small
grains of tin, are sent to the stamps; those of the third class C, which
are last removed from the surface of the bath of tin, are set apart, and
re-smelted, as containing a considerable quantity of metal in the form
of grain tin. These scoriæ are in small quantity. The stamp slag
contains fully 5 per cent. of metallic tin.

As soon as the scoriæ are cleared away, the channel is opened which
leads to the basin of reception, into which the tin consequently flows
out. Here it is left for some time, that the scoriæ which may be still
mixed with the metal, may separate, in virtue of the difference of their
specific gravities. When the tin has sufficiently settled, it is lifted
out with ladles, and poured into cast-iron moulds, in each of which a
bit of wood is fixed, to form a hole in the ingot, for the purpose of
drawing it out when it becomes cold.

_Refining of tin._--The object of this operation is to separate from the
tin, as completely as possible, the metals reduced and alloyed along
with it. These are, principally, iron, copper, arsenic, and tungsten; to
which are joined, in small quantities, some sulphurets and arseniurets
that have escaped decomposition, a little unreduced oxide of tin, and
also some earthy matters which have not passed off with the scoriæ.

_Liquation._--The refining of tin consists of two operations; the first
being a liquation, which, in the interior, is effected in a
reverberatory furnace, similar to that employed in smelting the ore.
(_figs._ 1151, 1152.) The blocks being arranged on the hearth of the
furnace, near the bridge, are moderately heated; the tin melts, and
flows away into the refining-basin; but, after a certain time, the
blocks cease to afford tin, and leave on the hearth a residuum,
consisting of a very ferruginous alloy.

Fresh tin blocks are now arranged on the remains of the first; and thus
the liquation is continued till the refining-basin be sufficiently full,
when it contains about 5 tons. The residuums are set aside, to be
treated as shall be presently pointed out.

_Refining proper._--Now begins the second part of the process. Into the
tin-bath, billets of green wood are plunged, by aid of the gibbet above
described. The disengagement of gas from the green wood produces a
constant ebullition in the tin; bringing up to its surface a species of
froth, and causing the impurest and densest parts to fall to the bottom.
That froth, composed almost wholly of the oxides of tin and foreign
metals, is successively skimmed off, and thrown back into the furnace.
When it is judged that the tin has boiled long enough, the green wood is
lifted out, and the bath is allowed to settle. It separates into
different zones, the upper being the purest; those of the middle are
charged with a little of the foreign metals; and the lower are much
contaminated with them. When the tin begins to cool, and when a more
complete separation of its different qualities cannot be looked for, it
is lifted out in ladles, and poured into cast-iron moulds. It is
obvious, that the order in which the successive blocks are obtained, is
that of their purity; those formed from the bottom of the basin being
usually so impure, that they must be subjected anew to the refining
process, as if they had been directly smelted from the ore.

The refining operation takes 5 or 6 hours; namely, an hour to fill the
basin, three hours to boil the tin with the green wood, and from one to
two hours for the subsidence.

Sometimes a simpler operation, called _tossing_, is substituted for the
above artificial ebullition. To effect it, a workman lifts some tin in a
ladle, and lets it fall back into the boiler, from a considerable
height, so as to agitate the whole mass. He continues this manipulation
for a certain time; after which, he skims with care the surface of the
bath. The tin is afterwards poured into moulds, unless it be still
impure. In this case, the separation of the metals is completed by
keeping the tin in a fused state in the boiler for a certain period,
without agitation; whereby the upper portion of the bath (at least
one-half) is pure enough for the market.

The moulds into which the tin blocks are cast, are usually made of
granite. Their capacity is such, that each block shall weigh a little
more than three hundred weight. This metal is called block tin. The law
requires them to be stamped or _coined_ by public officers, before being
exposed to sale. The purest block tin is called refined tin.

The treatment just detailed gives rise to two stanniferous residuums,
which have to be smelted again. These are--

1. The scoriæ B and C, which contain some granulated particles of tin.

2. The dross found on the bottom of the reverberatory furnace, after
re-melting the tin to refine it.

The scoriæ C, are smelted without any preparation; but those marked B,
are stamped in the mill, and washed, to concentrate the tin grains; and
from this rich mixture, called _prillion_, smelted by itself, a tin is
procured of very inferior quality. This may be readily imagined, since
the metal which forms these granulations is what, being less fusible
than the pure tin, solidified quickly, and could not flow off into the
metallic bath.

Whenever all the tin blocks have thoroughly undergone the process of
liquation, the fire is increased, to melt the less fusible residuary
alloy of tin with iron and some other metals, and this is run out into a
small basin, totally distinct from the refining basin. After this alloy
has reposed for some time, the upper portion is lifted out into block
moulds, as impure tin, which needs to be refined anew. On the bottom and
sides of the basin there is deposited a white, brittle alloy, with a
crystalline fracture, which contains so great a proportion of foreign
metals, that no use can be made of it. About 3-1/2 tons of coal are
consumed in producing 2 of tin.

_Smelting of tin by the blast furnace._--This mode of reduction employs
only wood charcoal, and its object is to obtain tin of the maximum
purity to which it can be brought by manufacturing processes. The better
ores of the stream-works, and the finer tin sands, are selected for this
operation. The washings being always well performed, the oxide of tin is
exempt from every arsenical or sulphureous impurity, and is associated
with nothing but a little hematite. It is therefore never calcined.

The smelting is effected without addition; only, in a few cases, some of
the residuary matters of a former operation are added to the ore. About
a ton and six-tenths of wood charcoal are burned for one ton of fine
smelted tin. The only rule is, to keep the furnace always full of
charcoal and ore. The revived tin is received immediately in the first
basin; then run off into the second, where it is allowed to settle for
some time. The scoriæ that run off into the first basin, are removed as
soon as they fix. These scoriæ are divided into two classes; namely,
such as still retain tin oxide, and such as hold none of the metal in
that state, but only in granulations. The metallic bath is divided, by
repose, into horizontal zones, of different degrees of purity; the more
compound and denser matters falling naturally to the bottom of the
basin. The tin which forms the superior zones, being judged to be pure
enough, is transvased by ladles into the refining basin, previously
heated, and under which, if it is of cast-iron, a moderate fire is
applied. The tin near the bottom of the receiving basin is always laded
out apart, to be again smelted; sometimes, indeed, when the furnace is
turning out very impure tin, none of it is transvased into the second
basin; but the whole is cast into moulds, to be again treated in the
blast furnace.

In general they receive no other preparation, but the green wood
ebullition, before passing into the market. Sometimes, however, the
block of metal is heated till it becomes brittle, when it is lifted to a
considerable height, and let fall, by which it is broken to pieces, and
presents an agglomeration of elongated grains or _tears_; whence it is
called _grain tin_.

On making a comparative estimate of the expense by the _blowing-house_
process, and by the reverberatory furnace, it has been found that the
former yields about 66 per cent. of tin, in smelting the stream or
alluvial ore, whose absolute contents are from 75 to 78 parts of metal
in the hundred. One ton of tin consumes a ton and six-tenths of wood
charcoal, and suffers a loss of 15 per cent. In working with the
reverberatory furnace, it is calculated that ore whose mean contents by
an exact analysis are 70 per cent., yields 65 per cent. on the great
scale. The average value of tin ore, as sold to the smelter, is 50
pounds sterling per ton; but it fluctuates, of course, with the market
prices. In 1824, the ore of inferior quality cost 30_l._, while the
purest sold for 60_l._ One ton of tin, obtained from the reverberatory
furnace, cost--

  1-1/2 tons of ore, worth                   _£_75   0  0
  1-3/4 tons of coals, at 10_s._ per ton         0  17  6
  Wages of labour, interest on capital, &c.      3   0  0
                                                ---------
                                                78  17  6

On comparing these results with the former, we perceive that in a
_blowing-house_ the loss of tin is 15 per cent., whereas it is only 5 in
the reverberatory furnace. The expense in fuel is likewise much less
relatively in the latter process; for only 1-3/4 tons of coals are
consumed for one ton of tin; while a ton and six-tenths of wood charcoal
are burned to obtain the same quantity of tin in the blowing-house; and
it is admitted that one ton of wood charcoal is equivalent to two tons
of coal, in calorific effect. Hence every thing conspires to turn the
balance in favour of the reverberatory plan. The operation is also, in
this way, much simpler, and may be carried on by itself. The scoriæ,
besides, from the reverberatory hearth, contain less tin than those
derived from the same ores treated with charcoal by the blast, as is
done at Altenberg. It must be remembered, however, that the grain tin
procured by the charcoal process is reckoned to be finer, and fetches a
higher price; a superiority partly due to the purity of the ore reduced,
and partly to the purity of the fuel.

To test the quality of tin, dissolve a certain weight of it with heat in
muriatic acid; should it contain arsenic, brown-black flocks will be
separated during the solution, and arseniuretted hydrogen gas will be
disengaged, which, on being burned at a jet, will deposit the usual gray
film of metallic arsenic upon a white saucer held a little way above the
flame. Other metals present in the tin, are to be sought for, by
treating the above solution with nitric acid of spec. grav. 1·16, first
in the cold, and at last with heat and a small excess of acid. When the
action is over, the supernatant liquid is to be decanted off the
peroxidized tin, which is to be washed with very dilute nitric acid, and
both liquors are to be evaporated to dissipate the acid excess. If, on
the addition of water to the concentrated liquor, a white powder falls,
it is a proof that the tin contains bismuth; if on adding sulphate of
ammonia, a white precipitate appears, the tin contains lead; water of
ammonia added to supersaturation, will occasion reddish-brown flocks,
if iron is present; and on evaporating the supernatant liquid to
dryness, the copper will be obtained.

The uses of tin are very numerous. Combined with copper, in different
proportions, it forms bronze, and a series of other useful alloys; for
an account of which see COPPER. With iron, it forms tin-plate; with
lead, it constitutes pewter, and solder of various kinds (see LEAD).
Tin-foil coated with quicksilver makes the reflecting surface of glass
mirrors. (See GLASS.) Nitrate of tin affords the basis of the scarlet
dye on wool, and of many bright colours to the calico-printer and the
cotton-dyer. (See SCARLET and TIN MORDANTS.) A compound of tin with
gold, gives the fine crimson and purple colours to stained glass and
artificial gems. (See PURPLE OF CASSIUS.) Enamel is made by fusing oxide
of tin with the materials of flint glass. This oxide is also an
ingredient in the white and yellow glazes of pottery-ware.

An ACCOUNT of TIN coined in Cornwall and Devon, from 1817 to 1829
inclusive:--

  +------+-------+---------+
  |Years.|Blocks.|Tons.    |
  +------+-------+---------+
  | 1817 | 25,379|4,120    |
  | 1818 | 23,048|3,745-1/3|
  | 1819 | 18,881|3,065    |
  | 1820 | 17,084|2,773-1/2|
  | 1821 | 19,273|3,128    |
  | 1822 | 18,732|3,137    |
  | 1823 | 24,077|4,031    |
  | 1824 | 28,602|4,819    |
  | 1825 | 24,902|4,170    |
  | 1826 | 26,299|4,406    |
  | 1827 | 31,744|5,316    |
  | 1828 | 28,179|4,696    |
  | 1829 | 26,344|4,396    |
  +------+-------+---------+

  +---------------------+-------------+
  |   Tin imported.     |Tin exported.|
  |Duty, 50_s._ per cwt.|             |
  +-------+-------------+-------------+
  |       |   _Cwts._   |   _Cwts._   |
  | 1827  |    2,217    |    2,938    |
  | 1828  |    3,386    |    3,258    |
  | 1829  |    2,674    |    2,581    |
  | 1830  |   15,539    |   10,426    |
  | 1831  |    8,099    |   12,226    |
  | 1832  |   29,203    |   21,720    |
  | 1833  |   35,124    |   39,850    |
  | 1834  |   46,769    |   46,685    |
  | 1835  |   17,705    |   23,796    |
  | 1836  |   23,236    |   17,231    |
  +-------+-------------+-------------+

The principal importations are from the East India Company’s territories
and Ceylon:--they amounted in 1832 to 24,585 cwts.; in 1833 to 27,928;
in 1834 to 33,611; in 1835 to 10,104; and in 1836 to 17,729. From
Sumatra and Java 1961 cwts. were imported in 1832, and 1145 in 1834, but
in the other years greatly less.

  Declared  }           |           |           |           |
  value of  }  1827.    |  1829.    |  1831.    |  1833.    | 1835.
  tin and   }302,255_l._|235,178_l._|239,143_l._|282,176_l._|381,076_l._
  pewter    }           |           |           |           |
  wares and }           |           |           |           |
  tin-plates} 1828.     | 1830.     | 1832.     | 1834.     | 1836.
  exported  }266,651_l._|249,657_l._|243,259_l._|337,056_l._|387,951_l._
  in        }           |           |           |           |

Of these goods, from two-fifths to three-fifths go to the United States
of America.

ABSTRACT of TIN coined in Cornwall and Devon, in the year ending June
30, 1835; from the _Mining Review_, vol. iii.

  +---------------------------+-----------+-------------+------------+
  |                           |Blocks of  |  Blocks of  |            |
  |                           |Grain Tin. | Common Tin. |   Totals.  |
  |         Smelters.         +-----+-----+------+------+------+-----+
  |                           |1834.|1835.|1834. |1835. |1834. |1835.|
  +---------------------------+-----+-----+------+------+------+-----+
  |Daubuz and Co.             | 728 | 875 | 6114 | 4494 | 6842 | 5369|
  |Grenfell and Boase         | 344 | 196 | 3776 | 3097 | 4120 | 3293|
  |Bolitho and Sons           | 229 | 153 | 3829 | 3099 | 4058 | 3252|
  |R. and J. Michell          | 101 |  75 |  709 |  575 |  810 |  650|
  |Wheal Vor Adventurers      |  -- |  -- | 3925 | 4069 | 3925 | 4069|
  |Taylor, Sons and Co.       |  -- | 112 |   -- | 1250 |   -- | 1362|
  |John Batten and Son        |  28 |  49 | 2352 | 2351 | 2380 | 2400|
  |Joseph Carne               |  -- |  -- |  896 |  851 |  896 |  851|
  |William Cornish            |  -- |  -- |  622 |  574 |  622 |  574|
  |Gill and Co. (at Morwelham)|  -- |  -- |  758 |   -- |  758 |   --|
  |    Ditto    (at Calstock) |  60 |  -- |  605 |   -- |  665 |   --|
  |Rundle, Paul and Co.       |  -- |  12 |   -- | 1545 |   -- | 1557|
  |                           +-----+-----+------+------+------+-----+
  |             Total         |1490 |1472 |23586 |21905 |25076 |23377|
  +---------------------------+-----+-----+------+------+------+-----+

Total, in 1834, 4180 tons; in 1835, 3899 tons. (6 blocks = 1 ton.)


TINCAL, crude borax.


TINCTORIAL MATTER. One of the most curious and valuable facts
ascertained upon this subject, is, that madder kept in casks, in a warm
place, undergoes a species of fermentation, which, by ripening or rather
deoxidizing the colouring-matter, increases its dyeing power by no less
than from 20 to 50 per cent. See M. H. Schlumberger’s memoir read to the
_Société Industrielle de Mulhausen_, 24 November, 1837.


TINCTURE is a title used by apothecaries to designate alcohol, in a
somewhat dilute state, impregnated with the active principles of either
vegetable or animal substances.


TIN-GLASS, is a name of bismuth.


TIN MORDANTS, for dyeing scarlet:--

_Mordant_ A, as commonly made by the dyers, is composed of 8 parts of
aquafortis, 1 part of common salt or sal ammoniac, and 1 of granulated
tin. This preparation is very uncertain.

_Mordant_ B.--Pour into a glass globe with a long neck, 3 parts of pure
nitric acid at 30° B.; and 1 part of muriatic acid at 17°; shake the
globe gently, avoiding the corrosive vapours, and put a loose stopper in
its mouth. Throw into this nitro-muriatic acid, one-eighth of its weight
of pure tin, in small bits at a time. When the solution is complete, and
settled, decant it into bottles, and close them with ground stoppers. It
should be diluted only when about to be used.

_Mordant_ C, by Dambourney.--In two drams Fr. (144 grs.) of pure
muriatic acid, dissolve 18 grains of Malacca tin. This is reckoned a
good mordant for brightening or fixing the colour of peachwood.

_Mordant_ D, by Hellot.--Take 8 ounces of nitric acid, diluted with as
much water; dissolve in it half an ounce of sal ammoniac, and 2 drams of
nitre. In this acid solution dissolve one ounce of granulated tin of
Cornwall, observing not to put in a fresh piece till the preceding be
dissolved.

_Mordant_ E, by Scheffer.--Dissolve one part of tin in four of a
nitro-muriatic acid, prepared with nitric acid diluted with its own
weight of water, and one thirty-secondth of sal ammoniac.

_Mordant_ F, by Poërner.--Mix one pound of nitric acid with one pound of
water, and dissolve in it an ounce and a half of sal ammoniac. Stir it
well, and add, by very slow degrees, two ounces of tin turned into thin
ribbons upon the lathe.

_Mordant_ G, by Berthollet.--Dissolve in nitric acid of 30° B.,
one-eighth of its weight of sal ammoniac, then add by degrees one-eighth
of its weight of tin, and dilute the solution with one-fourth of its
weight of water.

_Mordant_ K, by Dambourney.--In one dram (72 grs.) of muriatic acid at
17°, one of nitric acid at 30°, and 18 grains of water, dissolve, slowly
and with some heat, 18 grains of fine Malacca tin.

_Mordant_ L, is the birch bark prescribed by Dambourney.--This bark,
dried and ground, is said to be a very valuable substance for fixing the
otherwise fugitive colours produced by woods, roots, archil, &c.


TIN-PLATE. The only alloy of iron interesting to the arts, is that with
tin, in the formation of _tin-plate_, or _white-iron_.

The sheet iron intended for this manufacture is refined with charcoal
instead of coke, subsequently rolled to various degrees of thinness, and
cut into rectangles of different sizes, by means of a shearing-machine
driven by a water-wheel, which will turn out 100 boxes a day, or four
times the number cut by hand labour. The first step towards tinning, is
to free the metallic surface from every particle of oxide or impurity,
for any such would inevitably prevent the iron from alloying with the
tin. The plates are next bent separately by hand into a saddle or Λ
shape, and ranged in a reverberatory oven, so that the flame may play
freely among them, and heat them to redness. They are then plunged into
a bath, composed of four pounds of muriatic acid diluted with three
gallons of water, for a few minutes, taken out and drained on the floor,
and once more exposed to ignition in a furnace, whereby they are
_scaled_, that is to say, cast their scales. The above bath will suffice
for scaling 1800 plates. When taken out, they are beat level and smooth
on a cast-iron block, after which they appear mottled blue and white, if
the _scaling_ has been thoroughly done. They are next passed through
_chilled_ rolls or cast-iron cylinders, rendered very hard by being cast
in thick iron moulds, as has been long practised by the Scotch founders
in casting bushes for cart-wheels. After this process of _cold rolling_,
the plates are immersed, for ten or twelve hours, in an acidulous lye,
made by fermenting bran-water, taking care to set them separately on
edge, and to turn them at least once, so that each may receive a due
share of the operation. From this lye-steep they are transferred into a
leaden trough, divided by partitions, and charged with dilute sulphuric
acid. Each compartment is called a _hole_ by the workmen, and is
calculated to receive about 225 plates, the number afterwards packed up
together in a _box_. In this liquid they are agitated about an hour,
till they become perfectly bright, and free from such black spots as
might stain their surface at the time of immersion. This process, called
pickling, is both delicate and disagreeable, requiring a good workman,
at high wages. The temperature of the two last steeps should be at least
90° or 100° F., which is kept up by stoves in the apartments. The plates
are finally scoured with hemp and sand in a body of water, and then put
aside for use in a vessel of pure water, under which they remain bright
and free from rust for many months, a very remarkable circumstance.

The _tinning_ follows these preparatory steps. A range of rectangular
cast-iron pots is set over a fire-flue in an apartment called the
_stow_, the workmen stationing themselves opposite to the narrow ends.
The first rectangle in the range is the tin-pot; the second is the
wash-pot, with a partition in it; the third is the grease-pot; the
fourth is the pan, grated at bottom; the fifth is the list-pot, and is
greatly narrower than any of the rest: they are all of the same length.

The prepared plates, dried by rubbing bran upon them, are first immersed
one by one in a pot filled with melted tallow alone, and are left there
for nearly an hour. They are thence removed, with the adhering grease,
into pot No. 1., filled with a melted mixture of block and grain tin,
covered with about four inches of tallow, slightly carbonized. This pot
is heated by a fire, playing under its bottom and round its sides, till
the metal becomes so hot as nearly to inflame the grease. Here about 340
plates are exposed, upright, to the action of the tin for an hour and a
half, or more, according to their thickness. They are next lifted out,
and placed upon an iron grating, to let the superfluous metal drain off;
but this is more completely removed in the next process, called
_washing_.

Into the wash-pot, No. 2., filled with melted _grain_ tin, the workman
puts the above plates, where the heat detaches the ribs, and drops.
There is a longitudinal partition in it, for keeping the drop of tin
that rises in washing from entering the vessel where the last dip is
given. Indeed, the metal in the wash-pot, after having acted on 60 or 70
boxes, becomes so foul, that the weight of a block (300 cwt.) of it, is
transferred into the tin-pot, No. 1., and replaced by a fresh block of
grain tin. The plates being lifted out of the wash-pot, with tongs held
in the left hand of the workman, are scrubbed on each side with a
peculiar hempen brush, held in his right hand, then dipped for a moment
in the hot tin, and forthwith immersed in the adjoining grease-pot, No.
3. This requires manual dexterity; and though only three-pence be paid
for brushing and tin-washing 225 plates, yet a good workman can earn six
shillings and three-pence in twelve hours, by putting 5625 plates
through his hands. The final tin-dip is useful to remove the marks of
the brush, and to make the surface uniformly bright. To regulate the
temperature of the tallow-pot, and time during which the plates are left
in it, requires great skill and circumspection on the part of the
workman. If kept in it too long, they would be deprived to a certain
extent of their silvery lustre; and if too short, streaks of tin would
disfigure their surface. As a thick plate retains more heat after being
lifted out of the washing-pot, it requires a proportionally cooler
grease-pot. This pot has pins fixed within it, to keep the plates
asunder; and whenever the workman has transferred five plates to it, a
boy lifts the first out into the cold adjoining pan, No. 4.; as soon as
the workman transfers a sixth plate, the boy removes the second; and so
on. The manufacture is completed by removing the wire of tin left on the
under edge of the plates, in consequence of their vertical position in
the preceding operations. This is the business of the _list-boy_, who
seizes the plates when they are cool enough to handle, and puts the
lower edge of each, one by one, into the list-pot, No. 5., which
contains a very little melted tin, not exceeding a quarter of an inch in
depth. When he observes the wire-edge to be melted, he takes out the
plate, and, striking it smartly with a thin stick, detaches the
superfluous metal, which leaves merely a faint stripe where it lay. This
mark may be perceived on every tin-plate in the market.

The plates are finally prepared for packing up in their boxes, by being
well cleansed from the tallow, by friction with bran.

Mr. Thomas Morgan obtained a patent, in September, 1829, for clearing
the sheet-iron plates with dilute sulphuric acid in a _hole_, instead of
_scaling_ them in the usual way, previous to their being cold rolled,
annealed, and tinned; whereby, he says, a better article is produced at
a cheaper rate.

_Crystallized tin-plate_, see MOIRÉE METALLIQUE. It would seem that the
acid merely lays bare the crystalline structure really present on every
sheet, but masked by a film of redundant tin. Though this showy article
has become of late years vulgarized by its cheapness, it is still
interesting in the eyes of the practical chemist. The English tin-plates
marked F, answer well for producing the _Moirée_, by the following
process. Place the tin-plate, slightly heated, over a tub of water, and
rub its surface with a sponge dipped in a liquor composed of four parts
of aquafortis, and two of distilled water, holding one part of common
salt or sal ammoniac in solution. Whenever the crystalline spangles seem
to be thoroughly brought out, the plate must be immersed in water,
washed either with a feather or a little cotton (taking care not to rub
off the film of tin that forms the feathering), forthwith dried with a
low heat, and coated with a lacquer varnish, otherwise it loses its
lustre in the air. If the whole surface is not plunged at once in cold
water, but if it be partially cooled by sprinkling water on it, the
crystallization will be finely variegated with large and small figures.
Similar results will be obtained by blowing cold air through a pipe on
the tinned surface, while it is just passing from the fused to the solid
state; or a variety of delineations may be traced, by playing over the
surface of the plate with the pointed flame of a blowpipe.

The following TABLE shows the several sizes of tin-plates, the marks by
which they are distinguished, and their current wholesale prices in
London:--

  +------------------+---------+----+------+--------+----------------+
  |Names.            |Sizes.   |No. |Weight|Marks   |Prices per      |
  |                  |         |in a|of    |on the  |box, in         |
  |                  |         |box.|each  |boxes.  +--------+-------+
  |                  |         |    |box.  |        | 1823.  | 1838. |
  +------------------+---------+----+------+--------+--------+-------+
  |                  |_Inches._|    |c q  l|        |_s._    |_s. d._|
  |Common, No. 1.    |13-3/4 by|    |      |        |        |       |
  |                  |10       | 225|1 0  0|CI.     |47      | 35    |
  |  Ditto     2.    |13-1/4 --|    |      |        |        |       |
  |                  | 9-1/4   |    |0 3 21|CII.    |45      | 33  6 |
  |  Ditto     3.    |12-3/4 --|    |      |        |        |       |
  |                  | 9-1/2   |    |0 3 16|CIII.   |43      | 32  9 |
  |Cross,     No. 1. |13-3/4 --|    |      |        |        |       |
  |                  |10       |    |1 1  0|XI.     |53      | 40  2 |
  |Two crosses,   1. |         |    |1 1 21|XXI.    |58      | 43  2 |
  |Three crosses, 1. |         |    |1 2 14|XXX. I. |63      | 47    |
  |Four crosses,  1. |         |    |1 3  7|XXXX. I.|        |       |
  |Common doubles    |16-3/4 --|    |      |        |        |       |
  |                  |12-1/2   | 100|0 3 21|CD.     |64-6}   | 48  6 |
  |Cross doubles     |         |    |1 0 14|XD.     |73-6}[A]| 56    |
  |Two cross do.     |         |    |1 1  7|XXD.    |81  }   | 60  6 |
  |Three cross do.   |         |    |1 2  0|XXXD.   |88-6}   | 65    |
  |Four cross do.    |         |    |1 2 21|XXXXD.  |        |       |
  |Com. small doubles| 5  -- 11| 200|1 2  0|CSD.    |69      | 51  6 |
  |Cross do.    do.  |         |    |1 2 21|XSD.    |75      | 56  0 |
  |Two cross    do.  |         |    |1 3 14|XXSD.   |80      | 59  6 |
  |Three do.    do.  |         |    |2 0  7|XXXSD.  |        |       |
  |Four  do.    do.  |         |    |2 1  0|XXXXSD. |        |       |
  |Waster’s com.     | 3-3/4 --|    |      |        |        |       |
  |No. 1.            |10       | 225|1 0  0|WCI.    |44      | 32  9 |
  |Ditto  cross,   1.|  ditto  |    |1 1  0|WXI.    |50      | 47  3 |
  +------------------+---------+----+------+--------+--------+-------+

  c = _cwt._
  q = _qrs._
  l = _lbs._
  [A] = 150 sheets in each.

These are the cash prices of one wholesale warehouse in Thames-street;
an immediately adjoining warehouse charges fully 1_s._ more upon the
standard CI, and proportionally upon the others.


TITANIUM, is a rare metal, discovered by Klaproth, in menachanite, in
1794. It has been detected since in the form of small cubes of a
copper-red colour, in some of the blast furnaces in Yorkshire. According
to Hassenfratz, its presence in small quantity does not impair the
malleability of iron. It is very brittle, so hard as to scratch steel,
and very light, having a specific gravity of only 5·3. It will not melt
in the heat of any furnace, nor dissolve, when crystallized, even in
nitro-muriatic acid; but only when in fine powder. By calcination with
nitre, it becomes oxygenated, and forms titanate of potassa. Traces of
this metal may be detected in many irons, both wrought and cast. The
principal ores of titanium are _sphene_, common and foliated, _rutile_,
_iserine_, _menachanite_, and _octahedrite_ or _pyramidal titanium ore_.
None of them has been hitherto applied to any use.


TOBACCO. It is said that the name tobacco was given by the Spaniards to
the plant, because it was first observed by them at Tabasco, or Tabaco,
a province of Yucatan in Mexico. In 1560, Nicot, the French ambassador
to Portugal, having received some tobacco from a Flemish merchant,
showed it, on his arrival in Lisbon, to the grand prior, and, on his
return into France, to Catherine of Medicis, whence it has been called
Nicotiana by the botanists. Admiral Sir Francis Drake having, on his way
home from the Spanish Main, in 1586, touched at Virginia, and brought
away some forlorn colonists, is reported to have first imported tobacco
into England. But, according to Lobel, this plant was cultivated in
Britain before the year 1570; and was consumed by smoking in pipes by
Sir Walter Raleigh, and companions, so early as the year 1584.

The plants are hung up to dry during four or five weeks; taken down out
of the sheds in damp weather, for in dry they would be apt to crumble
into pieces; stratified in heaps, covered up, and left to sweat for a
week or two, according to their quality and the state of the season;
during which time they must be examined frequently, opened up, and
turned over, lest they become too hot, take fire, or run into
putrefactive fermentation. This process needs to be conducted by skilful
and attentive operatives. An experienced negro can form a sufficiently
accurate judgment of the temperature, by thrusting his hand down into
the heap.

The tobacco thus prepared, or often without fermentation, is sent into
the market; but, before being sold, it must undergo the inspection of
officers, appointed by the state with very liberal salaries, who
determine its quality, and brand an appropriate stamp upon its casks, if
it be sound; but if it be bad, it is burned.

Our respectable tobacconists are very careful to separate all the
damaged leaves, before they proceed to their preparation, which they do
by spreading them in a heap upon a stone pavement, watering each layer
in succession, with a solution of sea salt, of spec. grav. 1·107, called
_sauce_, till a ton or more be laid; and leaving their principles to
react on each other for three or four days, according to the
temperature, and the nature of the tobacco. It is highly probable that
ammonia is the volatilizing agent of many odours, and especially of
those of tobacco and musk. If a fresh green leaf of tobacco be crushed
between the fingers, it emits merely the herbaceous smell common to many
plants; but if it be triturated in a mortar, along with a little
quicklime or caustic potash, it will immediately exhale the peculiar
odour of snuff. Now analysis shows the presence of muriate of ammonia in
this plant, and fermentation serves further to generate free ammonia in
it; whence, by means of this process, and lime, the odoriferous vehicle
is abundantly developed. If, on the other hand, the excess of alkaline
matter in the tobacco of the shops be saturated by a mild dry acid, as
the tartaric, its peculiar aroma will entirely disappear.

Tobacco contains a great quantity of an azotized principle, which by
fermentation produces abundance of ammonia; the first portions of which
saturate the acid juices of the plant, and the rest serve to volatilize
its odorous principles. The salt water is useful chiefly in moderating
the fermentation, and preventing it from passing into the putrefactive
stage; just as salt is sometimes added to saccharine worts in tropical
countries, to temper the fermentative action. The sea salt, or
concentrated sea water, which contains some muriate of lime, tends to
keep the tobacco moist, and is therefore preferable to pure chloride of
sodium for this purpose. Some tobacconists mix molasses with the salt
_sauce_, and ascribe to this addition the violet colour of the _macouba_
snuff of Martinique; and others add a solution of extract of liquorice.
The following prescription is that used by a skilful manufacturer:--In a
solution of the liquorice juice, a few figs are to be boiled for a
couple of hours; to the decoction, while hot, a few bruised anise-seeds
are to be added, and when cold, common salt to saturation. A little
silent spirit of wine being poured in, the mixture is to be equably, but
sparingly, sprinkled with the rose of a watering-pot, over the leaves of
the tobacco, as they are successively stratified upon the preparation
floor.

The fermented leaves, being next stripped of their middle ribs by the
hands of children, are sorted anew, and the large ones are set apart for
making cigars. Most of the tobaccos on sale in our shops are mixtures of
different growths: one kind of smoking tobacco, for example, consists of
70 parts of Maryland, and 30 of meagre Virginia; and one kind of snuff
consists of 80 parts of Virginia, and 30 parts of either Humesfort or
Warwick. The Maryland is a very light tobacco, in thin yellow leaves;
that of Virginia is in large brown leaves, unctuous or somewhat gluey on
the surface, having a smell somewhat like the figs of Malaga; that of
Havannah is in brownish, light leaves, of an agreeable and rather spicy
smell; it forms the best cigars. The Carolina tobacco is less unctuous
than the Virginian; but in the United States it ranks next to the
Maryland.

The shag tobacco is dried to the proper point upon sheets of copper.

Tobacco is cut into what is called shag tobacco by knife-edged chopping
stamps, a machine somewhat similar to that represented under METALLURGY,
_fig._ 670. For grinding the tobacco leaves into snuff, conical mortars
are employed, somewhat like that used by the Hindoos for grinding
sugar-canes, _fig._ 1080.; but the sides of the snuff-mill have sharp
ridges from the top to near the bottom.

Mr. L. W. Wright obtained a patent in August, 1827, for a
tobacco-cutting machine, which bears a close resemblance to the
well-known machines with revolving knives, for cutting straw into chaff.
The tobacco, after being squeezed into cakes, is placed upon a smooth
bed within a horizontal trough, and pressed by a follower and screws to
keep it compact. These cakes are progressively advanced upon the bed, or
fed in, to meet the revolving blades. The speed of the feeding-screw
determines the degree of fineness of the sections or particles into
which the tobacco is cut.

I was employed some years ago by the Excise, to analyze a quantity of
snuff, seized on suspicion of having been adulterated by the
manufacturer. I found it to be largely drugged with pearl-ashes, and to
be thereby rendered very pungent, and absorbent of moisture; an
economical method of rendering an effete article at the same time active
and aqueous.

According to the recent analysis of Possett and Reimann, 10,000 parts of
tobacco-leaves contain--6 of the peculiar chemical principle _nicotine_;
1 of _nicotianine_; 287 of slightly bitter extractive; 174 of gum, mixed
with a little malic acid; 26·7 of a green resin; 26 of vegetable
albumen; 104·8 of a substance analogous to gluten; 51 of malic acid; 12
of malate of ammonia; 4·8 of sulphate of potassa; 6·3 of chloride of
potassium; 9·5 of potassa, which had been combined with malic and nitric
acids; 16·6 of phosphate of lime; 24·2 of lime, which had been combined
with malic acid; 8·8 of silica; 496·9 of fibrous or ligneous matter;
traces of starch; and 88·28 of water.

_Nicotine_ is a transparent colourless liquid, of an alkaline nature. It
may be distilled in a retort plunged into a bath heated to 290°
Fahrenheit. It has a pricking, burning taste, which is very durable; and
a pungent disagreeable smell. It burns by means of a wick, with the
diffusion of a vivid light, and much smoke. It may be mixed with water
in all proportions. It is soluble also in acetic acid, oil of almonds,
alcohol, and ether, but not in oil of turpentine. It acts upon the
animal economy with extreme violence; and in the dose of one drop it
kills a dog. It forms salts with the acids. About one part of it may be
obtained by very skilful treatment from one thousand of good tobacco.

Tobacco imported into the United Kingdom, viz.--unmanufactured, in 1836,
52,232,907 lbs.; in 1837, 27,070,448 lbs.;--manufactured, and snuff, in
1836, 182,248 lbs.; in 1837, 642,287 lbs. Retained for home consumption,
unmanufactured, in 1836, 22,309,021 lbs.; in 1837, 22,504,343
lbs.:--manufactured, and snuff, in 1836, 159,226 lbs.; in 1837, 145,045
lbs. Duty received,--on unmanufactured tobacco, in 1836, _£_3,344,703;
in 1837, _£_3,375,125; on manufactured tobacco, and snuff, in 1836,
£71,560; in 1837, _£_65,220.


TOBACCO-PIPES. The practice of smoking tobacco has become so general in
many nations as to render the manufacture of tobacco-pipes a
considerable branch of industry. Some seek in the inhalation of
tobacco-smoke a pleasurable narcotism; others imagine it to be
beneficial to their health; but, in general, smoking is merely a dreamy
resource against ennui, which ere long becomes an indispensable
stimulus. The filthiness of this habit, the offensive odour which
persons under its influence emit from their mouths and clothes, the
stupor it too often occasions, as well as the sallow complexion, black
or carious teeth, and impaired digestion, all prove the great
consumption of tobacco to be akin in evil influence upon mankind to the
use of ardent spirits.

Tobacco-pipes are made of a fine-grained plastic white clay, to which
they have given the name. It is worked with water into a thin paste,
which is allowed to settle in pits, or it may be passed through a sieve,
to separate the siliceous or other stony impurities; the water is
afterwards evaporated till the clay becomes of a doughy consistence,
when it must be well kneaded to make it uniform. Pipe-clay is found
chiefly in the isle of Purbeck and Dorsetshire. It is distinguished by
its perfectly white colour, and its great adhesion to the tongue after
it is baked; owing to the large proportion of alumina which it contains.

A child fashions a ball of clay from the heap, rolls it out into a
slender cylinder upon a plank, with the palms of his hands, in order to
form the stem of the pipe. He sticks a small lump to the end of the
cylinder for forming the bowl; which having done, he lays the pieces
aside for a day or two, to get more consistence. In proportion as he
makes these rough figures, he arranges them by dozens on a board, and
hands them to the pipemaker.

The pipe is finished by means of a folding brass or iron mould,
channelled inside of the shape of the stem and the bowl, and capable of
being opened at the two ends. It is formed of two pieces, each hollowed
out like a half-pipe, cut as it were lengthwise; and these two jaws,
when brought together, constitute the exact space for making one pipe.
There are small pins in one side of the mould, corresponding to holes in
the other, which serve as guides for applying the two together with
precision.

The workman takes a long iron wire, with its end oiled, and pushes it
through the soft clay in the direction of the stem, to form the bore,
and he directs the wire by feeling with his left hand the progress of
its point. He lays the pipe in the groove of one of the jaws of the
mould, with the wire sticking in it; applies the other jaw, brings them
smartly together, and unites them by a clamp or vice, which produces the
external form. A lever is now brought down, which presses an oiled
stopper into the bowl of the pipe, while it is in the mould, forcing it
sufficiently down to form the cavity; the wire being meanwhile thrust
backwards and forwards so as to pierce the tube completely through. The
wire must become visible at the bottom of the bowl, otherwise the pipe
will be imperfect. The wire is now withdrawn, the jaws of the mould
opened, the pipe taken out, and the redundant clay removed with a knife.
After drying for a day or two, the pipes are scraped, polished with a
piece of hard wood, and the stems being bent into the desired form, they
are carried to the baking kiln, which is capable of firing fifty gross
in from 8 to 12 hours. A workman and a child can easily make five gross
of pipes in a day.

No tobacco-pipes are so highly prized as those made in Natolia, in
Turkey, out of meerschaum, a somewhat plastic magnesian stone, of a soft
greasy feel, which is formed into pipes after having been softened with
water. It becomes white and hard in the kiln.

[Illustration: 1155 1156]

A tobacco-pipe kiln should diffuse an equal heat to every part of its
interior, while it excludes the smoke of the fire. The crucible, or
large sagger, A, A, _figs._ 1155. and 1156., is a cylinder, covered in
with a dome. It is placed over the fireplace B, and enclosed within a
furnace of ordinary brickwork D, D, lined with fire-bricks E, E. Between
this lining and the cylinder, a space of about 4 inches all round is
left for the circulation of the flame. There are 12 supports or ribs
between the cylinder and the furnace lining, which form so many flues,
indicated by the dotted lines _x_, in _fig._ 1156. (the dotted circle
representing the cylinder). These ribs are perforated with occasional
apertures, as shown in _fig._ 1155., for the purpose of connecting the
adjoining flues; but the main bearing of the hollow cylinder is given by
five piers, _b_, _b_, _c_, formed of bricks projecting over and beyond
each other. One of these piers _c_, is placed at the back of the
fireplace, and the other four at the sides _b_, _b_. These project
nearly into the centre, in order to support and strengthen the bottom;
while the flues pass up between them, unite at the top of the cylinder
in the dome L, and discharge the smoke by the chimney N.

The lining F, E, E, of the chimney is open on one side to form the door,
by which the cylinder is charged and discharged. The opening is
permanently closed as high as _k_, _fig._ 1155., by an iron plate
plastered over with fire-clay; above this it is left open, and shut
merely with temporary brickwork while the furnace is going. When this is
removed, the furnace can be filled or emptied through the opening, the
cylindric crucible having a correspondent aperture in its side, which is
closed in the following ingenious way, while the furnace is in action.
The workman first spreads a layer of clay round the edge of the opening,
he then sticks the stems of broken pipes across from one side to the
other, and plasters up the interstices with clay, exactly like the
lath-and-plaster work of a ceiling. The whole of the cylinder, indeed,
is constructed in this manner, the bottom being composed of a great many
fragments of pipe stems, radiating to the centre; these are coated at
the circumference with a layer of clay. A number of bowls of broken
pipes are inserted in the clay; in these other fragments are placed
upright to form the sides of the cylinder. The ribs round the outside,
which form the flues, are made in the same way, as well as the dome L;
by which means the cylindric case may be made very strong, and yet so
thin as to require little clay in the building, a moderate fire to heat
it, while it is not apt to split asunder. The pipes are arranged within,
as shown in the figure, with their bowls resting against the
circumference and their ends supported on circular pieces of clay _r_,
which are set up in the centre for that purpose. Six small ribs are made
to project inwards all round the crucible, at the proper heights, to
support the different ranges of pipes, without having so many resting on
each other as to endanger their being crushed by the weight. By this
mode of distribution, the furnace may contain 50 gross, or 7200 pipes,
all baked within 8 or 9 hours; the fire being gradually raised, or
damped if occasion be, by a plate partially slid over the chimney top.


TODDY, _Sura_, _Mee-ra_, sweet juice.--The proprietors of coco-nut
plantations in the peninsula of India, and in the Island of Ceylon,
instead of collecting a crop of nuts, frequently reap the produce of the
trees by extracting sweet juice from the flower-stalk. When the
flowering branch is half shot, the toddy-drawers bind the stock round
with a young coco-nut leaf in several places, and beat the spadix with a
short baton of ebony. This beating is repeated daily for ten or twelve
days, and about the end of that period a portion of the flower-stalk is
cut off. The stump then begins to bleed, and an earthen vessel (chatty)
or a calabash is suspended under it, to receive the juice, which is by
the Europeans called _toddy_.

A thin slice is taken from the stump daily, and the toddy is removed
twice a day. A coco-nut frequently pushes out a new _spadix_ once a
month; and after each spadix begins to bleed, it continues to produce
freely for a month, by which time another is ready to supply its place.
The old spadix continues to give a little juice for another month, after
which it withers; so that there are sometimes two pots attached to a
tree at one time, but never more. Each of these spadices, if allowed to
grow, would produce a bunch of nuts from two to twenty. Trees in a good
soil produce twelve bunches in the year; but when less favourably
situated, they often do not give more than six bunches. The quantity of
six English pints of toddy is sometimes yielded by a tree daily.

Toddy is much in demand as a beverage in the neighbourhood of villages,
especially where European troops are stationed. When it is drunk before
sunrise, it is a cool, delicious, and particularly wholesome beverage;
but by eight or nine o’clock fermentation has made some progress, and it
is then highly intoxicating.[68]

  [68] Contributions to the History of the Coco-nut Tree. By Henry
  Marshall, Esq., Deputy Inspector of Hospitals.


TOLU, is a brownish-red balsam, extracted from the stem of the
_Myroxilon toluiferum_, a tree which grows in South America. It is
composed of resin, oil, and benzoic acid. Having an agreeable odour, it
is sometimes used in perfumery. It has a place in the Materia Medica,
but for what good reason I know not.


TOMBAC, is a white alloy of copper.


TONKA BEAN, the fruit of the _Dipterix odorata_, affords a concrete
crystalline volatile oil (_stearoptène_), called _coumarine_ by the
French. It is extracted by digestion with alcohol, which dissolves the
stearoptène, and leaves a fat oil. It has an agreeable smell, and a warm
taste. It is fusible at 122° Fahrenheit, and volatile at higher heats.


TOPAZ. See LAPIDARY.


TORTOISE-SHELL, or rather scales, a horny substance, that covers the
hard strong covering of a bony contexture, which encloses the _Testudo
imbricata_, Linn. The lamellæ or plates of this tortoise are 13 in
number, and may be readily separated from the bony part by placing fire
beneath the shell, whereby they start asunder. They vary in thickness
from one-eighth to one-quarter of an inch, according to the age and size
of the animal, and weigh from 5 to 25 pounds. The larger the animal, the
better is the shell. This substance may be softened by the heat of
boiling water; and if compressed in this state by screws in iron or
brass moulds, it may be bent into any shape. The moulds being then
plunged in cold water, the shell becomes fixed in the form imparted by
the mould. If the turnings or filings of tortoise-shell be subjected
skilfully to gradually increased compression between moulds immersed in
boiling water, compact objects of any desired ornamental figure or
device may be produced. The soldering of two pieces of scale is easily
effected, by placing their edges together, after they are nicely filed
to one bevel, and then squeezing them strongly between the long flat
jaws of hot iron pincers, made somewhat like a hairdresser’s
curling-tongs. The pincers should be strong, thick, and just hot enough
to brown paper slightly, without burning it. They may be soldered also
by the heat of boiling water, applied along with skilful pressure. But
in whatever way this process is attempted, the surfaces to be united
should be made very smooth, level, and clean; the least foulness, even
the touch of a finger, or breathing upon them, would prevent their
coalescence. See HORN.


TOUCH-NEEDLES, and TOUCH-STONE, are means of ascertaining the quality of
gold trinkets. See ASSAY.


TOW. See FLAX.


TRAGACANTH, GUM. (_Gomme adracante_, Fr.; _Traganth_, Germ.) See GUM.


TRAVERTINO. See TUFA.


TREACLE, is the viscid brown uncrystallizable syrup which drains from
the sugar-refining moulds. Its specific gravity is generally 1·4, and it
contains upon an average 75 per cent. of solid matter, by my
experiments.


TRIPOLI (_Terre pourrie_, Fr.; _Tripel_, Germ.); rotten-stone; is a
mineral of an earthy fracture, a yellowish-gray or white colour,
composition impalpably fine, meagre to the touch, does not adhere to the
tongue, and burns white. Its analogue, the _Polierschiefer_, occurs in
thin flat foliated pieces, of the above colours, occasionally striped;
soft, absorbent of water; spec. grav. 1·9. to 2·2.

M. Ehrenberg has shown that both of these friable homogeneous rocks,
which consist almost entirely of silica, are actually composed of the
exuviæ or rather the skeletons of infusoria (_animalcula_) of the family
of _Barcillariæ_, and the genera _Cocconema_, _Gonphonema_, &c. They are
recognised with such distinctness in the microscope, that their
analogies with living species may be readily traced; and in many cases
there are no appreciable differences between the living and the
petrified. The species are distinguished by the number of partitions or
transverse lines upon their bodies. The length is about 1/288 of a line.
M. Ehrenberg made his observations upon the tripolis of Billen in
Bohemia of Santafiora in Tuscany, of the Isle of France, and of
Francisbad, near Eger.

The meadow iron ore (_Fer limoneux des marais_) is composed almost
wholly of the _Gaellonella ferruginea_. Most of these infusoria are
lacustrine; but others are marine, particularly the _tripolis_ of the
Isle of France.

According to the chemical analysis of Bucholz, tripoli consists
of--silica, 81; alumina, 1·5; oxide of iron, 8; sulphuric acid, 3·45;
water, 4·55. This specimen was probably found in a coal-field. The
tripoli of Corfu is reckoned the best for scouring or brightening brass
and other metals. Mr. Phillips found in the Derbyshire rotten-stone
(near Bakewell), 86 of alumina, 4 of silica, and 10 of carbon--being a
remarkable difference in composition from the Bohemian.


TUFA, or TUF, is a gray deposit of calcareous carbonate, from springs
and streams.


TULA METAL, is an alloy of silver, copper, and lead.


TUNGSTEN (Eng. and Fr.; _Wolfram_, Germ.); is a peculiar metal, which
occurs in the state of an acid (the _tungstic_), combined with various
bases, as with lime, the oxides of iron, manganese, and lead. The metal
is obtained by reduction of the ore, or the deoxidizement of the acid,
in the form of a dark steel-gray powder, which assumes under the
burnisher a feeble metallic lustre. Its specific gravity is 17·22.


TURBITH MINERAL, is the yellow subsulphate of mercury.


TURF (_Peat_, Scotch; _Tourbe_, Fr.; _Torf_, Germ.); consists of
vegetable matter, chiefly of the moss family, in a state of partial
decomposition by the action of water. Cut, during summer, into
brick-shaped pieces, and dried, it is extensively used as fuel by the
peasantry in every region where it abounds. The dense black turf, which
forms the lower stratum of a peat-moss, is much contaminated with iron,
sulphur, sand, &c., while the lighter turf of the upper strata, though
nearly pure vegetable matter, is too bulky for transportation, and too
porous for factory fuel. These defects have been happily removed by Mr.
Williams, managing director of the Dublin Steam Navigation Company, who
has recently obtained a patent for a method of converting the lightest
and purest beds of peat-moss, or bog, into the four following products:
1. A brown combustible solid, denser than oak; 2. A charcoal, twice as
compact as that of hard wood; 3. A factitious coal; and 4. A factitious
coke; each of which possesses very valuable properties.

Mr. D’Ernst, artificer of fire-works to Vauxhall, has proved, by the
severe test of coloured fires, that the turf charcoal of Mr. Williams is
20 per cent. more combustible than that of oak. Mr. Oldham, engineer of
the Bank of England, has applied it in softening his steel plates and
dies, with remarkable success. But one of the most important results of
Mr. Williams’s invention is, that with 10 cwts. of pitcoal, and 2-1/2
cwts. of his factitious coal, the same steam power is now obtained, in
navigating the Company’s ships, as with 17-1/2 cwts. of pitcoal alone;
thereby saving 30 per cent. in the stowage of fuel. What a prospect is
thus opened up of turning to admirable account the unprofitable bogs of
Ireland; and of producing, from their inexhaustible stores, a superior
fuel for every purpose of arts and engineering.

The turf is treated as follows:--Immediately after being dug, it is
triturated under revolving edge-wheels, faced with iron plates
perforated all over their surface, and is forced by the pressure through
these apertures, till it becomes a species of pap, which is freed from
the greater part of its moisture by squeezing in a hydraulic press
between layers of caya cloth, then dried, and coked in suitable
ovens.--(See CHARCOAL, and PITCOAL, COKING OF.) Mr. Williams makes his
factitious coal by incorporating with pitch or rosin, melted in a
cauldron, as much of the above charcoal, ground to powder, as will form
a doughy mass, which is moulded into bricks in its hot and plastic
state. From the experiments of M. Le Sage, detailed in the 5th volume of
“The Repertory of Arts,” charred ordinary turf seems to be capable of
producing a far more intense heat than common charcoal. It has been
found preferable to all other fuel for case-hardening iron, tempering
steel, forging horseshoes, and welding gun-barrels. Since turf is
partially carbonized in its native state, when it is condensed by the
hydraulic press, and fully charred, it must evidently afford a charcoal
very superior in calorific power to the porous substance generated from
wood by fire.


TURKEY RED, is a brilliant dye produced on cotton goods by MADDER.


TURMERIC, _Curcuma_, _Terra merita_, (_Souchet_, or _Safran des Indes_,
Fr.; _Gelbwurzel_, Germ.); is the root of the _Curcuma longa_ and
_rotunda_, a plant which grows in the East Indies, where it is much
employed in dyeing yellow, as also as a condiment in curry sauce or
powder. The root is knotty, tubercular, oblong, and wrinkled;
pale-yellow without, and brown-yellow within; of a peculiar smell, a
taste bitterish and somewhat spicy. It contains a peculiar yellow
principle, called _curcumine_, a brown, colouring-matter, a volatile
oil, starch, &c. The yellow tint of turmeric is changed to brown-red by
alkalis, alkaline earths, subacetate of lead, and several metallic
oxides; for which reason, paper stained with it is employed as a
chemical test.

Turmeric is employed by the wool-dyers for compound colours which
require an admixture of yellow, as for cheap browns and olives. As a
yellow dye, it is employed only upon silk. It is a very fugitive colour.
A yellow lake may be made by boiling turmeric powder with a solution of
alum, and pouring the filtered decoction upon pounded chalk.


TURNSOLE. See ARCHIL and LITMUS.


TURQUOIS. See LAPIDARY.


TURPENTINE (_Térébinthine_, Fr.; _Terpenthin_, Germ.); is a substance
which flows out of incisions made in the stems of several species of
pines. It has the consistence and gray-yellow colour of honey. It has a
smell which is not disagreeable to many persons, a warm, sharp,
bitterish taste; dries into a solid in the air, with the evaporation of
its volatile oil. It becomes quite fluid at a moderate elevation of
temperature, and burns at a higher heat, with a bright but very
fuliginous flame. There are several varieties of turpentine.

1. _Common turpentine_, is extracted from incisions in the _Pinus abies_
and _Pinus silvestris_. It has little smell; but a bitter burning taste.
It consists of the volatile oil of turpentine to the amount of from 5 to
25 per cent.; and of rosin or colophony.

2. _Venice turpentine_, is extracted from the _Pinus larix_ (larch), and
the French turpentine from the _Pinus maritima_. The first comes from
Styria, Hungary, the Tyrol, and Switzerland, and contains from 18 to 25
per cent. of oil; the second, from the south of France, and contains no
more than 12 per cent. of oil. The oil of all the turpentines is
extracted by distilling them along with water. They dissolve in all
proportions in alcohol, without leaving any residuum. They also combine
with alkaline lyes, and in general with the salifiable bases. Venice
turpentine contains also succinic acid.

3. Turpentine of Strasbourg is extracted from the _Pinus picea_ and
_Abies excelsa_. It affords 33·5 per cent. of volatile oil, and some
volatile or crystallizable resin, with extractive matter and succinic
acid.

4. Turpentine of the Carpathian mountains, and of Hungary; the first of
which comes from the _Pinus cembra_, and the second from the _Pinus
mugos_. They resemble that of Strasbourg.

5. Turpentine of Canada, called Canada balsam, is extracted from the
_Pinus canadensis_ and _balsamea_. Its smell is much more agreeable than
that of the preceding species.

6. Turpentine of Cyprus or Chio, is extracted from the _Pistacea
terebinthus_. It has a yellow, greenish, or blue-green colour. Its smell
is more agreeable, and taste less acrid, than those of the preceding
sorts.

Common Turpentine imported into the United Kingdom, in 1836, 370,981
cwts. 1 qr. 26 lbs.; in 1837, 415,023 cwts. 1 qr. 10 lbs. Retained for
home consumption, in 1836, 341,693 cwts. 18 lbs.; in 1837, 405,772 cwts.
2 qrs. 14 lbs. Duty received, in 1836, _£_74,052; in 1837, _£_87,918.


TURPENTINE, OIL OF, sometimes called essence of turpentine. As found in
commerce, it contains more or less rosin, from which it may be freed by
re-distillation along with water. It is colourless, limpid, very fluid,
and possessed of a very peculiar smell. Its specific gravity, when pure,
is 0·870; that of the oil commonly sold in London, is 0·875. It always
reddens litmus paper, from containing a little succinic acid. According
to Oppermann, the oil which has been repeatedly rectified over chloride
of calcium, consists of 84·60 carbon, 11·735 hydrogen, and 3·67 oxygen.
When oil of turpentine contains a little alcohol, it burns with a clear
flame; but otherwise it affords a very smoky flame. Chlorine inflames
this oil; and muriatic acid converts it into a crystalline substance,
like camphor. It is employed extensively in varnishes, paints, &c., as
also in medicine.


TUTENAG, is an alloy of copper and zinc.


TYPE, (_Caractère_, Fr.; _Druckbuchstabe_, Germ.) The first care of the
letter-cutter is to prepare well-tempered steel punches, upon which he
draws or marks the exact shape of the letter, with pen and ink if it be
large, but with a smooth blunted point of a needle if it be small; and
then, with a proper sized and shaped graver and sculpter, he digs or
scoops out the metal between the strokes upon the face of the punch,
leaving the marks untouched and prominent. He next works the outside
with files till it be fit for the matrix. Punches are also made by
hammering down the hollows, filing up the edges, and then hardening the
soft steel. Before he proceeds to sink and justify the matrix, he
provides a mould to justify them by, of which a good figure is shown in
plate XV., _Miscellany_, _figs._ 2. 3. of _Rees’s Cyclopædia_.

[Illustration: 1157]

A matrix is a piece of brass or copper, about an inch and a half long,
and thick in proportion to the size of the letter which it is to
contain. In this metal the face of the letter intended to be cast is
sunk, by striking it with the punch to a depth of about one eighth of an
inch. The mould, _fig._ 1157., in which the types are cast, is composed
of two parts. The outer part is made of wood, the inner of steel. At the
top it has a hopper-mouth _a_, into which the fused type-metal is
poured. The interior cavity is as uniform as if it had been hollowed out
of a single piece of steel; because each half, which forms two of the
four sides of the letter, is exactly fitted to the other. The matrix is
placed at the bottom of the mould, directly under the centre of the
orifice, and is held in its position by a spring _b_. Every letter that
is cast can be loosened from the matrix only by removing the pressure on
the spring.

A good type-foundry is always provided with several furnaces, each
surmounted with an iron pot containing the melted alloy, of 3 parts of
lead and 1 of antimony. Into this pot the founder dips the very small
iron ladle, to lift merely as much metal as will cast a single letter at
a time. Having poured in the metal with his right hand, and returned the
ladle to the melting-pot, the founder throws up his left hand, which
holds the mould, above his head, with a sudden jerk, supporting it with
his right hand. It is this movement which forces the metal into all the
interstices of the matrix; for without it, the metal, especially in the
smaller moulds, would not be able to expel the air and reach the bottom.
The pouring in the metal, the throwing up the mould, the unclosing it,
removing the pressure of the spring, picking out the cast letter,
closing the mould again, and re-applying the spring to be ready for a
new operation, are all performed with such astonishing rapidity and
precision, that a skilful workman will turn out 500 good letters in an
hour, being at the rate of one every eighth part of a minute. A
considerable piece of metal remains attached to the end of the type as
it quits the mould. There are nicks upon the lower edge of the types, to
enable the compositor to place them upright, without looking at them.

From the table of the _caster_, the heap of types turned out of his
mould, is transferred from time to time to another table, by a boy,
whose business it is to break off the superfluous metal, and that he
does so rapidly as to clear from 2000 to 5000 types in an hour; a very
remarkable dispatch, since he must seize them by their edges, and not by
their feeble flat sides. From the breaking-off boy, the types are taken
to the _rubber_, a man who sits in the centre of the workshop with a
grit-stone slab on a table before him, and having on the fore and middle
finger of his right hand a piece of tarred leather, passes each broad
side of the type smartly over the stone, turning it in the movement, and
that so dexterously, as to be able to rub 2000 types in an hour.

From the rubber, the types are conveyed to a boy, who, with equal
rapidity sets them up in lines, in a long shallow frame, with their
faces uppermost and nicks outwards. This frame, containing a full line,
is put into the dresser’s hands, who polishes them on each side, and
turning them with their faces downwards, cuts a groove or channel in
their bottom, to make them stand steadily on end. It is essential that
each letter be perfectly symmetrical and square; the least inequality of
their length would prevent them from making a fair impression; and were
there the least obliquity in their sides, it would be quite impossible,
when 200,000 single letters are combined, as in one side of the _Times_
newspaper, that they could hold together as they require to do, when
wedged up in the chases, as securely as if that side of type form a
solid plate of metal. Each letter is finally tied up in lines of
convenient length, the proportionate numbers of each variety, small
letters, points, large capitals, small capitals, and figures, being
selected, when the fount of type is ready for delivery to the printer.

The sizes of types cast in this country vary, from the smallest, called
diamond, of which 205 lines are contained in a foot length, to those
letters employed in placards, of which a single letter may be 3 or 4
inches high. The names of the different letters and their dimensions, or
the number of lines which each occupies in a foot, are stated in the
following table:--

  Double Pica     41-1/2
  Paragon         44-1/2
  Great Primer    51-1/4
  English         64
  Pica            71-1/2
  Small Pica      83
  Long Primer     89
  Bourgeois      102-1/4
  Brevier        112-1/2
  Minion         128
  Nonpareil      143
  Pearl          178
  Diamond        205

T. Aspinwall, Esq., the American consul, obtained, in May, 1828, a
patent for an improved method of casting printing types by means of a
mechanical process, being a communication from a foreigner residing
abroad. The machine is described, with six explanatory figures, in the
second series of Newton’s Journal, vol. v. page 212. The patentee does
not claim, as his invention, any of the parts separately, but the
general process and arrangement of machinery; more particularly the
manner of suspending a swing table (upon which the working parts are
mounted) out of the horizontal and perpendicular position; the mode of
moving the table with the parts of the mould towards the melting-pot;
the manner of bringing the parts of the mould together, and keeping them
closed during the operation of casting the types. Several other
mechanical schemes have been proposed for founding types, but I have
been informed by very competent judges, Messrs. Clowes, that none of
them can compete in practical utility with that dexterity and precision
of handiwork, which I have often seen practised in their great printing
establishment in Stamford-street.




U.


ULTRAMARINE (_Outremer_, Fr.; _Ultramarins_, Germ.); is a beautiful blue
pigment obtained from the variegated blue mineral, called lazulite
(_lapis lazuli_), by the following process:--Grind the stone to
fragments, rejecting all the colourless bits, calcine at a red heat,
quench in water, and then grind to an impalpable powder along with
water, in a paint-mill, (see PAINTS, GRINDING OF,) or with a porphyry
slab and muller. The paste being dried, is to be rubbed to powder, and
passed through a silk sieve. 100 parts of it are to be mixed with 40 of
rosin, 20 of white wax, 25 of linseed oil, and 15 of Burgundy pitch,
previously melted together. This resinous compound is to be poured hot
into cold water; kneaded well first with two spatulas, then with the
hands, and then formed into one or more small rolls. Some persons
prescribe leaving these pieces in the water during 15 days, and then
kneading them in it, whereby they give out the blue pigment, apparently
because the ultramarine matter adheres less strongly than the _gangue_,
or merely siliceous matter of the mineral, to the resinous paste. MM.
Clement and Desormes, who were the first to divine the true nature of
this pigment, think that the soda contained in the lazulite, uniting
with the oil and the rosin, forms a species of soap, which serves to
wash out the colouring-matter. If it should not separate readily, water
heated to about 150° F. should be had recourse to. When the water is
sufficiently charged with blue colour, it is poured off and replaced by
fresh water; and the kneading and change of water are repeated till the
whole of the colour is extracted. Others knead the mixed resinous mass
under a slender stream of water, which runs off with the colour into a
large earthen pan. The first waters afford, by rest, a deposit of the
finest ultramarine; the second, a somewhat inferior article, and so on.
Each must be washed afterwards with several more waters, before they
acquire the highest quality of tone; then dried separately, and freed
from any adhering particles of the pitchy compound by digestion in
alcohol. The remainder of the mass being melted with oil, and kneaded in
water containing a little soda or potash, yields an inferior pigment,
called _ultramarine ashes_. The best _ultramarine_ is a splendid blue
pigment, which works well with oil, and is not liable to change by time.
Its price in Italy was five guineas the ounce, a few years ago, but it
is now greatly reduced.

The blue colour of _lazulite_ had been always ascribed to iron, till MM.
Clement and Desormes, by a most careful analysis, showed it to consist
of--silica, 34; alumina, 33; sulphur, 3; soda, 22; and that the iron,
carbonate of lime, &c. were accidental ingredients, essential neither to
the mineral, nor to the pigment made from it. By another analyst, the
constituents are said to be--silica, 44; alumina, 35; and soda, 21; and
by a third, potassa was found instead of soda, showing shades of
difference in the composition of the stone.

Till a few years ago, every attempt failed to make ultramarine
artificially. At length, in 1828, M. Guimet resolved the problem, guided
by the analysis of MM. Clement and Desormes, and by an observation of M.
Tassaert, that a blue substance like ultramarine was occasionally
produced on the sandstone hearths of his reverberatory soda furnaces. Of
M. Guimet’s finest pigment I received a bottle several years ago, from
my friend M. Merimée, secretary of the _Ecole de Beaux Arts_, which has
been found by artists little, if any, inferior to the lazulite
ultramarine. M. Guimet sells it at 60 francs per pound French,--which is
little more than two guineas the English pound. He has kept his process
secret. But M. Gmelin, of Tübingen, has published a prescription for
making it; which consists in enclosing carefully in a Hessian crucible a
mixture of 2 parts of sulphur, and 1 of dry carbonate of soda, heating
them gradually to redness till the mass fuses, and then sprinkling into
it by degrees another mixture, of silicate of soda, and aluminate of
soda; the first containing 72 parts of silica, and the second 70 parts
of alumina. The crucible must be exposed after this for an hour to the
fire. The ultramarine will be formed by this time; only it contains a
little sulphur, which can be separated by means of water. M. Persoz,
professor of chemistry at Strasbourg, has likewise succeeded in making
an ultramarine, of perhaps still better quality than that of M. Guimet.
Lastly, M. Robiquet has announced, that it is easy to form ultramarine,
by heating to redness a proper mixture of kaolin (China clay), sulphur,
and carbonate of soda. It would therefore appear, from the preceding
details, that ultramarine may be regarded as a compound of silicate of
alumina, silicate of soda, with sulphuret of sodium; and that to the
reaction of the last constituent upon the former two, it owes its
colour.


UMBER, is a massive mineral; fracture large and flat; conchoidal in the
great, very fine earthy in the small; dull; colour, liver,
chestnut,--dark yellowish brown; opaque; does not soil, but writes;
adheres strongly to the tongue, feels a little rough and meagre, and is
very soft; specific gravity 2·2. It occurs in beds with brown jasper in
the Island of Cyprus, and is used by painters as a brown colour, and to
make varnish dry quickly.


URANIUM, is a rare metal, first discovered by Klaproth, in the black
mineral called _pechblende_, found in a mine near Johann-Georgen-Stadt,
in Saxony, and which is a sulphuret of uranium. A double phosphate of
uranium and copper, called _green uranite_, and _uran mica_, occurs in
Cornwall. It has been reduced to the metallic state by various devices,
but it has hardly the appearance of metal to the naked eye, and from the
rarity of its ores is not likely to be of any importance in the arts.


URAO, is the native name of a sesquicarbonate of soda found at the
bottom of certain lakes in Mexico, especially to the north of Zacatecas,
and in several other provinces; also in South America at Columbia, 48
English miles from Merida.




V.


VALONIA, is a kind of acorn, imported from the Levant and the Morea for
the use of tanners, as the husk or cup contains abundance of tannin. The
quantity imported for home consumption in 1836, was 80,511 cwts.; of
which Turkey furnished 58,724, Italy and the Italian islands, 7209.


VANADIUM, is a metal discovered by Sefström, in 1830, in a Swedish iron,
remarkable for its ductility, extracted from the iron mine of Jaberg,
not far from Jönköping. Its name is derived from Vanadis, a Scandinavian
idol. This metal has been found in the state of vanadic acid, in a lead
ore from Zimapan, in Mexico. The finery cinders of the Jaberg iron
contain more vanadium than the metal itself. It exists in it as vanadic
acid. For the reduction of this acid to vanadium, see Berzelius’s
_Traité de Chimie_, vol. iv. p. 644. Vanadium is white, and when its
surface is polished, it resembles silver or molybdenum more than any
other metal. It combines with oxygen into two oxides and an acid.

The vanadate of ammonia, mixed with infusion of nutgalls, forms a black
liquid, which is the best writing-ink hitherto known. The quantity of
the salt requisite is so small as to be of no importance when the
vanadium comes to be more extensively extracted. The writing is
perfectly black. The acids colour it blue, but do not remove it, as they
do tannate of iron: the alkalis, diluted so far as not to injure the
paper, do not dissolve it; and chlorine, which destroys the black
colour, does not, however, make the traces illegible, even when they are
subsequently washed with a stream of water. It is perfectly fluent, and,
being a chemical solution, stands in want of no viscid gum to suspend
the colour, like common ink. The influence of time upon it remains to be
tried.


VANILLA, is the oblong narrow pod of the _Epidendron vanilla_, Linn., of
the natural family _Orchideæ_, which grows in Mexico, Colombia, Peru,
and on the banks of the Oronoco.

The best comes from the forests round the village of Zentila, in the
intendancy of Oaxaca.

The vanilla plant is cultivated in Brazil, in the West Indies, and some
other tropical countries, but does not produce fruit of such a delicious
aroma as in Mexico. It clings like a parasite to the trunks of old
trees, and sucks the moisture which their bark derives from the lichens,
and other cryptogamia, but without drawing nourishment from the tree
itself, like the ivy and misletoe. The fruit is subcylindric, about 8
inches long, one-celled, siliquose, and pulpy within. It should be
gathered before it is fully ripe.

When about 12000 of these pods are collected, they are strung like a
garland by their lower end, as near as possible to the foot-stalk; the
whole are plunged for an instant in boiling water to blanch them; they
are then hung up in the open air, and exposed to the sun for a few
hours. Next day they are lightly smeared with oil, by means of a
feather, or the fingers; and are surrounded with oiled cotton, to
prevent the valves from opening. As they become dry, on inverting their
upper end, they discharge a viscid liquid from it, and they are pressed
at several times with oiled fingers to promote its flow. The dried pods
lose their appearance, grow brown, wrinkled, soft, and shrink into
one-fourth of their original size. In this state they are touched a
second time with oil, but very sparingly; because, with too much oil,
they would lose much of their delicious perfume. They are then packed
for the market, in small bundles of 50 or 100 in each, enclosed in lead
foil, or tight metallic cases. As it comes to us, vanilla is a capsular
fruit, of the thickness of a swan’s quill, straight, cylindrical, but
somewhat flattened, truncated at the top, thinned off at the ends,
glistening, wrinkled, furrowed lengthwise, flexible, from 5 to 10 inches
long, and of a reddish-brown colour. It contains a pulpy parenchyma,
soft, unctuous, very brown, in which are imbedded black, brilliant, very
small seeds. Its smell is ambrosiacal and aromatic; its taste hot, and
rather sweetish. These properties seem to depend upon an essential oil,
and also upon benzoic acid, which forms efflorescences upon the surface
of the fruit. The pulpy part possesses alone the aromatic quality; the
pericarpium has hardly any smell.

The kind most esteemed in France, is called _leq_ vanilla; it is about 6
inches long, from 1/4 to 1/3 of an inch broad, narrowed at the two ends,
and curved at the base; somewhat soft and viscid, of a dark-reddish
colour, and of a most delicious flavour, like that of balsam of Peru. It
is called vanilla _givrées_, when it is covered with efflorescences of
benzoic acid, after having been kept in a dry place, and in vessels not
hermetically closed.

The second sort, called _vanilla simarona_, or bastard, is a little
smaller than the preceding, of a less deep brown hue, drier, less
aromatic, destitute of efflorescence. It is said to be the produce of
the wild plant, and is brought from St. Domingo.

A third sort, which comes from Brazil, is the _vanillon_, or large
vanilla of the French market; the _vanilla pamprona_ or _bova_ of the
Spaniards. Its length is from 5 to 6 inches; its breadth from one-half
to three-quarters of an inch. It is brown, soft, viscid, almost always
open, of a strong smell, but less agreeable than the _leq_. It is
sometimes a little spoiled by an incipient fermentation. It is cured
with sugar, and enclosed in tin-plate boxes, which contain from 20 to 60
pods.

Vanilla, as an aromatic, is much sought after by makers of chocolate,
ices, and creams; by confectioners, perfumers, and liquorists, or
distillers. It is difficultly reduced to fine particles; but it may be
sufficiently attenuated by cutting it into small bits, and grinding
these along with sugar. The odorous principle can, for some purposes, be
extracted by alcohol. Their analysis by Bucholz is unsatisfactory, and
refers obviously to the coarsest sort. Berzelius says that the
efflorescences are not acid.


VAPOUR (_Vapeur_, Fr.; _Dampf_, Germ.); is the state of elastic or
aeriform fluidity into which any substance, naturally solid or liquid at
ordinary temperatures, may be converted by the agency of heat. See
EVAPORATION.


VARNISH. (_Vernis_, Fr.; _Firniss_, Germ.); is a solution of resinous
matter, which is spread over the surface of any body, in order to give
it a shining, transparent, and hard coat, capable of resisting, in a
greater or less degree, the influences of air and moisture. Such a coat
consists of the resinous parts of the solution, which remain in a thin
layer upon the surface, after the liquid solvent has either evaporated
away, or has dried up. When large quantities of spirit varnish are to be
made, a common still, mounted with its capital and worm, is the vessel
employed for containing the materials, and it is placed in a steam or
water bath. The capital should be provided with a stuffing-box, through
which a stirring-rod may pass down to the bottom of the still, with a
cross-piece at its lower end, and a handle or winch at its top. After
heating the bath till the alcohol boils and begins to distil, the heat
ought to be lowered, that the solution may continue to proceed in an
equable manner, with as little evaporation of spirit as possible. The
operation may be supposed to be complete when the rod can be easily
turned round. The varnish must be passed through a silk sieve of proper
fineness; then filtered through porous paper, or allowed to clear
leisurely in stone jars. The alcohol which has come over should be added
to the varnish, if the just proportions of the resins have been
introduced at first. The following are reckoned good French recipes for
varnishes:--

_White spirit varnish._--Sandarach, 250 parts; mastic in tears, 64;
elemi resin, 32; turpentine (Venice), 64; alcohol, of 85 per cent., 1000
parts by measure.

The turpentine is to be added after the resins are dissolved. This is a
brilliant varnish, but not so hard as to bear polishing.

_Varnish for the wood toys of Spa._--Tender copal, 75 parts; mastic,
12·5; Venice turpentine, 6·5; alcohol, of 95 per cent., 100 parts by
measure; water ounces, for example, if the other parts be taken in
ounces.

The alcohol must be first made to act upon the copal, with the aid of a
little oil of lavender or camphor, if thought fit; and the solution
being passed through a linen cloth, the mastic must be introduced. After
it is dissolved, the Venice turpentine, previously melted in a
water-bath, should be added; the lower the temperature at which these
operations are carried on, the more beautiful will the varnish be. This
varnish ought to be very white, very drying, and capable of being
smoothed with pumice-stone and polished.

_Varnish for certain parts of carriages._--Sandarach, 190 parts; pale
shellac, 95; rosin, 125; turpentine, 190; alcohol, at 85 per cent., 1000
parts by measure.

_Varnish for cabinet-makers._--Pale shellac, 750 parts; mastic, 64;
alcohol, of 90 per cent., 1000 parts by measure. The solution is made in
the cold, with the aid of frequent stirring. It is always muddy, and is
employed without being filtered.

With the same resins and proof spirit a varnish is made for the
bookbinders to do over their morocco leather.

_The varnish of Watin, for gilded articles._--Gum lac, in grain, 125
parts; gamboge, 125; dragon’s blood, 125; annotto, 125; saffron, 32.
Each resin must be dissolved in 1000 parts by measure, of alcohol of 90
per cent.; two separate tinctures must be made with the dragon’s blood
and annotto, in 1000 parts of such alcohol; and a proper proportion of
each should be added to the varnish, according to the shade of golden
colour wanted.

For fixing engravings or lithographs upon wood, a varnish called
_mordant_ is used in France, which differs from others chiefly in
containing more Venice turpentine, to make it sticky; it consists
of--sandarach, 250 parts; mastic in tears, 64; rosin, 125; Venice
turpentine, 250; alcohol, 1000 parts by measure.

_Copal varnish._--Hard copal, 300 parts; drying linseed or nut oil, from
125 to 250 parts; oil of turpentine, 500; these three substances are to
be put into three separate vessels; the copal is to be fused by a
somewhat sudden application of heat; the drying oil is to be heated to a
temperature a little under ebullition, and it is to be added by small
portions at a time to the melted copal. When this combination is made,
and the heat a little abated, the essence of turpentine, likewise
previously heated, is to be introduced by degrees: some of the volatile
oil will be dissipated at first; but more being added, the union will
take place. Great care must be taken to prevent the turpentine vapour
from catching fire, which might occasion serious accidents to the
operator. When the varnish is made, and has cooled down to about the
130th degree of Fahr., it may be strained through a filter, to separate
the impurities and undissolved copal.

Almost all varnish-makers think it indispensable to combine the drying
oil with the copal, before adding the oil of turpentine; but in this
they are mistaken. Boiling oil of turpentine combines very readily with
fused copal; and, in some cases, it would probably be preferable to
commence the operation with it, adding it in successive small
quantities. Indeed, the whitest copal varnish can be made only in this
way; for if the drying oil have been heated to nearly its boiling point,
it becomes coloured, and darkens the varnish.

This varnish improves in clearness by keeping. Its consistence may be
varied by varying the proportions of the ingredients, within moderate
limits. Good varnish, applied in summer, should become so dry in 24
hours that the dust will not stick to it, nor receive an impression from
the fingers. To render it sufficiently dry and hard for polishing, it
must be subjected for several days to the heat of a stove.

_Milk of wax_, is a valuable varnish, which may be prepared as
follows:--Melt in a porcelain capsule a certain quantity of white wax,
and add to it, while in fusion, an equal quantity of spirit of wine, of
sp. gr. 0·830; stir the mixture, and pour it upon a large porphyry slab.
The granular mass is to be converted into a paste by the muller, with
the addition, from time to time, of a little alcohol; and as soon as it
appears to be smooth and homogeneous, water is to be introduced in small
quantities successively, to the amount of four times the weight of the
wax. This emulsion is to be then passed through canvas, in order to
separate such particles as may be imperfectly incorporated.

The _milk of wax_, thus prepared, may be spread with a smooth brush upon
the surface of a painting, allowed to dry, and then fused by passing a
hot iron (salamander) over its surface. When cold, it is to be rubbed
with a linen cloth to bring out the lustre. It is to the unchangeable
quality of an encaustic of this nature, that the antient paintings upon
the walls of Herculaneum and Pompeii owe their freshness at the present
day.

The most recent practical account of the manufacture of varnishes, is
that communicated by Mr. J. Wilson Neil to the Society of Arts, and
published in the 49th volume of their “Transactions.”

The building or shed wherein varnish is made, ought to be quite detached
from any buildings whatever, to avoid accidents by fire. For general
purposes, a building about 18 feet by 16 is sufficiently large for
manufacturing 4000 gallons and upwards annually, provided there are
other convenient buildings for the purpose of holding the utensils, and
warehousing the necessary stock.

Procure a copper pan, made like a common washing-copper, which will
contain from fifty to eighty gallons, as occasion may require; when
wanted, set it upon the boiling furnace, and fill it up with linseed oil
within five inches of the brim. Kindle a fire in the furnace underneath,
and manage the fire so that the oil shall gradually, but slowly,
increase in heat for the first two hours; then increase the heat to a
gentle simmer; and if there is any scum on the surface, skim it off with
a copper ladle, and put the skimming away. Let the oil boil gently for
three hours longer; then introduce, by a little at a time, one quarter
of an ounce of the best calcined magnesia for every gallon of oil,
occasionally stirring the oil from the bottom. When the magnesia is all
in, let the oil boil rather smartly for one hour; it will then be
sufficient. Lay a cover over the oil, to keep out the dust while the
fire is withdrawn and extinguished by water; next uncover the oil, and
leave it till next morning; and then, while it is yet hot, ladle it into
the carrying-jack, or let it out through the pipe and cock; carry it
away, and deposit it in either a tin or leaden cistern, for wooden
vessels will not hold it; let it remain to settle for at least three
months. The magnesia will absorb all the acid and mucilage from the oil,
and fall to the bottom of the cistern, leaving the oil clear and
transparent, and fit for use. Recollect, when the oil is taken out, not
to disturb the bottoms, which are only fit for black paint.

GENERAL OBSERVATIONS AND PRECAUTIONS TO BE OBSERVED IN MAKING VARNISHES.

Set on the boiling-pot with 8 gallons of oil; kindle the fire; then lay
the fire in the gum-furnace; have as many 8lb. bags of gum-copal all
ready weighed up, as will be wanted; put one 8lb. into the pot, put fire
to the furnace, set on the gum-pot; in three minutes (if the fire is
brisk) the gum will begin to fuse and give out its gas, steam, and acid;
stir and divide the gum, and attend to the rising of it, as before
directed. 8lbs. of copal take in general from sixteen to twenty minutes
in fusing, from the beginning till it gets clear like oil, but the time
depends very much on the heat of the fire, and the attention of the
operator. During the first twelve minutes, while the gum is fusing, the
assistant must look to the oil, and bring it to a smart simmer; for it
ought to be neither too hot, nor yet too cold, but in appearance
beginning to boil, which he is strictly to observe, and, when ready, to
call out, “Bear a hand!” Then immediately both lay hold of a handle of
the boiling-pot, lift it right up, so as to clear the plate, carry it
out and place it on the ash-bed, the maker instantly returning to the
gum-pot, while the assistant puts three copper ladlefuls of oil into the
copper pouring-jack, bringing it in and placing it on the iron plate at
the back of the gum-pot to keep hot until wanted. When the maker finds
the gum is nearly all completely fused, and that it will in a few
minutes be ready for the oil, let him call out, “Ready oil!” The
assistant is then to lift up the oil-jack with both hands, one under the
bottom and the other on the handle, laying the spout over the edge of
the pot, and wait until the maker calls out, “Oil!” The assistant is
then to pour in the oil as before directed, and the boiling to be
continued until the oil and gum become concentrated, and the mixture
looks clear on the glass; the gum-pot is now to be set upon the
brick-stand until the assistant puts three more ladlefuls of hot oil
into the pouring-jack, and three more into a spare tin for the third run
of gum. There will remain in the boiling-pot still 3-1/2 gallons of oil.
Let the maker put his right hand down the handle of the gum-pot near to
the side, with his left hand near the end of the handle, and with a firm
grip lift the gum-pot, and deliberately lay the edge of the gum-pot over
the edge of the boiling-pot until all its contents run into the
boiling-pot. Let the gum-pot be held, with its bottom turned upwards,
for a minute right over the boiling-pot. Observe, that whenever the
maker is beginning to pour, the assistant stands ready with a thick
piece of old carpet, without holes, and sufficiently large to cover the
mouth of the boiling-pot should it catch fire during the pouring, which
will sometimes happen if the gum-pot is very hot; should the gum-pot
fire, it has only to be kept bottom upwards, and it will go out of
itself; but if the boiling-pot should catch fire, during the pouring,
let the assistant throw the piece of carpet quickly over the blazing
pot, holding it down all round the edges; in a few minutes it will be
smothered. The moment the maker has emptied the gum-pot, he throws into
it half a gallon of turpentine, and with the _swish_ immediately washes
it from top to bottom, and instantly empties it into the flat tin jack:
he wipes the pot dry, and puts in 8lbs. more gum, and sets it upon the
furnace; proceeding with this run exactly as with the last, and
afterwards with the third run. There will then be 8 gallons of oil and
24lbs. of gum in the boiling-pot, under which keep up a brisk strong
fire until a scum or froth rises and covers all the surface of the
contents, when it will begin to rise rapidly. Observe, when it rises
near the rivets of the handles, carry it from the fire, and set it on
the ash-bed, stir it down again, and scatter in the driers by a little
at a time; keep stirring, and if the frothy head goes down, put it upon
the furnace, and introduce _gradually_ the remainder of the driers,
always carrying out the pot when the froth rises near the rivets. In
general, if the fire be good, all the time a pot requires to boil, from
the time of the last gum being poured in, is about three and a half or
four hours; but _time_ is no criterion for a beginner to judge by, as it
may vary according to the weather, the quality of the oil, the quality
of the gum, the driers, or the heat of the fire, &c.; therefore, about
the third hour of boiling, try it on a bit of glass, and keep it boiling
until it feels strong and stringy between the fingers; it is then boiled
sufficiently to carry it on the ash-bed, and to be stirred down until it
is cold enough to mix, which will depend much on the weather, varying
from half an hour, in dry frosty weather, to one hour in warm summer
weather. Previous to beginning to mix, have a sufficient quantity of
turpentine ready, fill the pot, and pour in, stirring all the time at
the top or surface, as before directed, until there are fifteen gallons,
or five tins of oil of turpentine introduced, which will leave it quite
thick enough if the gum is good, and has been well run; but if the gum
was of a weak quality, and has not been well fused, there ought to be no
more than twelve gallons of turpentine mixed, and even that may be too
much. Therefore, when twelve gallons of turpentine have been introduced,
have a flat saucer at hand, and pour into it a portion of the varnish,
and in two or three minutes it will show whether it is too thick; if not
sufficiently thin, add a little more turpentine, and strain it off
quickly. As soon as the whole is stored away, pour in the turpentine
washings, with which the gum-pots have been washed, into the
boiling-pot, and with the swish quickly wash down all the varnish from
the pot sides; afterwards, with a large piece of woollen rag dipped in
pumice-powder, wash and polish every part of the inside of the
boiling-pot, performing the same operation on the ladle and stirrers;
rinse them with the turpentine washings, and at last rinse them
altogether in clean turpentine, which also put to the washings; wipe dry
with a clean soft rag the pot, ladle, stirrer, and funnels, and lay the
sieve so as to be completely covered with turpentine, which will always
keep it from gumming up. The foregoing directions concerning running the
gum, and pouring in the oil, and also boiling off and mixing, are, with
very little difference, to be observed in the making of all sorts of
copal varnishes, except the differences of the quantities of oil, gum,
&c., which will be found under the various descriptions by name, which
will be hereafter described.

The choice of linseed oil is of peculiar consequence to the
varnish-maker. Oil from fine full-grown ripe seed, when viewed in a
phial, will appear limpid, pale, and brilliant; it is mellow and sweet
to the taste, has very little smell, is specifically lighter than impure
oil, and, when clarified, dries quickly and firmly, and does not
materially change the colour of the varnish when made, but appears
limpid and brilliant.

_Copal varnishes for fine paintings, &c._--Fuse 8 lbs. of the very
cleanest pale African gum copal, and, when completely run fluid, pour in
two gallons of hot oil, old measure; let it boil until it will string
very strong; and in about fifteen minutes, or while it is yet very hot,
pour in three gallons of turpentine, old measure, and got from the top
of a cistern. Perhaps during the mixing, a considerable quantity of the
turpentine will escape; but the varnish will be so much the brighter,
transparent, and fluid; and will work freer, dry more quickly, and be
very solid and durable when dry. After the varnish has been strained, if
it is found too thick, before it is quite cold, heat as much turpentine,
and mix with it, as will bring it to a proper consistence.

_Cabinet varnish._--Fuse 7 lbs. of very fine African gum copal, and pour
in half a gallon of pale clarified oil; in three or four minutes after,
if it feel stringy, take it out of doors, or into another building where
there is no fire, and mix with it three gallons of turpentine;
afterwards strain it, and put it aside for use. This, if properly
boiled, will dry in ten minutes; but if too strongly boiled, will not
mix at all with the turpentine; and _sometimes_, when boiled with the
turpentine, will mix, and yet refuse to incorporate with any other
varnish less boiled than itself: therefore it requires a nicety which is
only to be learned from practice. This varnish is chiefly intended for
the use of japanners, cabinet-painters, coach-painters, &c.

_Best body copal varnish for coach-makers, &c._--This is intended for
the body parts of coaches and other similar vehicles, intended for
polishing.

Fuse 8 lbs. of fine African gum copal; add two gallons of clarified oil
(old measure); boil it very slowly for four or five hours, until quite
stringy; mix with three gallons and a half of turpentine; strain off,
and pour it into a cistern. As they are too slow in drying,
coach-makers, painters, and varnish-makers, have introduced to two pots
of the preceding varnish, one made as follows:--

  8     lbs. of fine pale gum animé;
  2     gallons of clarified oil;
  3-1/2 gallons of turpentine.
        To be boiled four hours.

_Quick drying body copal varnish, for coaches, &c._

  (1.) 8     lbs. of the best African copal
       2     gallons of clarified oil;
         1/2 lb. of dried sugar of lead;
       3-1/2 gallons of turpentine.
             Boiled till stringy, and mixed and strained.

  (2.) 8     lbs. of fine gum animé;
       2     gallons of clarified oil;
         1/4 lb. of white copperas;
       3-1/2 gallons of turpentine.
             Boiled as before.

To be mixed and strained while hot into the other pot. These two pots
mixed together will dry in six hours in winter, and in four in summer;
it is very useful for varnishing old work on dark colours, &c.

_Best pale carriage varnish._

  (1.) 8     lbs. 2d sorted African copal;
       2-1/2 gallons of clarified oil.
             Boiled till very stringy.
         1/4 lb. of dried copperas;
         1/4 lb. of litharge;
       5-1/2 gallons of turpentine.
             Strained, &c.

  (2.) 8     lbs. of 2d sorted gum animé;
       2-1/2 gallons of clarified oil;
       1/4   lb. of dried sugar of lead;
       1/4   lb. of litharge;
       5-1/2 gallons of turpentine.
             Mix this to the first while hot.

This varnish will dry hard, if well boiled, in four hours in summer, and
in six in winter. As the name denotes, it is intended for the varnishing
of the wheels, springs, and carriage parts of coaches, chaises, &c.;
also, it is that description of varnish which is generally sold to and
used by house-painters, decorators, &c., as from its drying quality and
strong gloss, it suits their general purposes well.

_Second carriage varnish._

  8     lbs. of 2d sorted gum animé;
  2-3/4 gallons of fine clarified oil;
  5-1/4 gallons of turpentine;
    1/4 lb. of litharge;
    1/4 lb. of dried sugar of lead;
    1/4 lb. of dried copperas.
        Boiled and mixed as before.

_Wainscot varnish._

  8     lbs. of 2d sorted gum animé;
  3     gallons of clarified oil;
    1/4 lb. of litharge;
    1/4 lb. of dried sugar of lead;
  5-1/2 gallons of turpentine.
        To be well boiled until it strings very strong, and then mixed
        and strained.

Mahogany varnish is made either with the same proportions, with a little
darker gum; otherwise it is wainscot varnish, with a small portion of
gold size.

_Black japan_, is made by putting into the set-pot 48 pounds of Naples,
or any other of the foreign asphaltums (except the Egyptian). As soon as
it is melted, pour in 10 gallons of raw linseed oil; keep a moderate
fire, and fuse 8 pounds of dark gum animé in the gum-pot; mix it with 2
gallons of hot oil, and pour it into the set-pot. Afterwards fuse 10
pounds of dark or sea amber in the 10 gallon iron pot; keep stirring it
while fusing; and whenever it appears to be overheated, and rising too
high in the pot, lift it from the fire for a few minutes. When it
appears completely fused, mix in 2 gallons of hot oil, and pour the
mixture into the set-pot; continue the boiling for 3 hours longer, and
during that time introduce the same quantity of driers as before
directed: draw out the fire, and let it remain until morning; then boil
it until it rolls hard, as before directed: leave it to cool, and
afterwards mix with turpentine.

_Pale amber varnish._--Fuse 6 pounds of fine picked, very pale
transparent amber in the gum-pot, and pour in 2 gallons of hot clarified
oil. Boil it until it strings very strong. Mix with 4 gallons of
turpentine. This will be as fine as body copal, will work very free, and
flow well upon any work it is applied to: it becomes very hard, and is
the most durable of all varnishes; it is very excellent to mix in copal
varnishes, to give them a hard and durable quality. Observe; amber
varnish will always require a long time before it is ready for
polishing.

_Best Brunswick black._--In an iron pot, over a slow fire, boil 45
pounds of foreign asphaltum for at least 6 hours; and during the same
time boil in another iron pot 6 gallons of oil which has been previously
boiled. During the boiling of the 6 gallons, introduce 6 pounds of
litharge gradually, and boil until it feels stringy between the fingers;
then ladle or pour it into the pot containing the boiling asphaltum. Let
the mixture boil until, upon trial, it will roll into hard pills; then
let it cool, and mix it with 25 gallons of turpentine, or until it is of
a proper consistence.

_Iron-work black._--Put 48 pounds of foreign asphaltum into an iron pot,
and boil for 4 hours. During the first 2 hours, introduce 7 pounds of
red lead, 7 pounds of litharge, 3 pounds of dried copperas, and 10
gallons of boiled oil; add 1 eight-pound run of dark gum, with 2 gallons
of hot oil. After pouring the oil and gum, continue the boiling 2 hours,
or until it will roll into hard pills like japan. When cool, thin it off
with 30 gallons of turpentine, or until it is of a proper consistence.
This varnish is intended for blacking the iron-work of coaches and other
carriages, &c.

_A cheap Brunswick black._--Put 28 pounds of common black pitch, and 28
pounds of common asphaltum made from gas tar, into an iron pot; boil
both for 8 or 10 hours, which will evaporate the gas and moisture; let
it stand all night, and early next morning, as soon as it boils, put in
8 gallons of boiled oil; then introduce, gradually, 10 pounds of red
lead, and 10 pounds of litharge, and boil for 3 hours, or until it will
roll very hard. When ready for mixing, introduce 20 gallons of
turpentine, or more, until of a proper consistence. This is intended for
engineers, founders, ironmongers, &c.; it will dry in half an hour, or
less, if properly boiled.

_Axioms observed in the making of copal varnishes._--The more minutely
the gum is run, or fused, the greater the quantity, and the stronger the
produce. The more regular and longer the boiling of the oil and gum
together is continued, the more fluid or free the varnish will extend on
whatever it is applied to. When the mixture of oil and gum is too
suddenly brought to string by too strong a heat, the varnish requires
more than its just proportion of turpentine to thin it, whereby its oily
and gummy quality is reduced, which renders it less durable; neither
will it flow so well in laying on. The greater proportion of oil there
is used in varnishes, the less they are liable to crack, because the
tougher and softer they are. By increasing the proportion of gum in
varnishes, the thicker will be the stratum, the firmer they will set
solid, and the quicker they will dry. When varnishes are quite new made,
and must be sent out for use before they are of sufficient age, they
must always be left thicker than if they were to be kept the proper
time. Varnish made from African copal alone possesses the most
elasticity and transparency. Too much driers in varnish render it opaque
and unfit for delicate colours. Copperas does not combine with varnish,
but only hardens it. Sugar of lead does combine with varnish. Turpentine
improves by age; and varnish by being kept in a warm place. All copal or
oil varnishes require age before they are used.

_Concluding observations._--All body varnishes are intended and ought to
have 1-1/2 lbs. of gum to each gallon of varnish, when the varnish is
strained off, and cold; but as the _thinning up_, or quantity of
turpentine required to bring it to its proper consistence, depends very
much upon the degree of boiling the varnish has undergone, therefore,
when the gum and oil have not been strongly boiled, it requires less
turpentine for that purpose; whereas, when the gum and oil are very
strongly boiled together, a pot of 20 gallons will require perhaps 3
gallons above the regular proportionate quantity; and if mixing the
turpentine is commenced too soon, and the pot not sufficiently cool,
there will be frequently above a gallon and a half of turpentine lost by
evaporation.

All carriage, wainscot, and mahogany varnish ought to have fully 1 pound
of gum for each gallon, when strained and cold; and should one pot
require more than its proportion of turpentine, the following pot can
easily be left not quite so strongly boiled; then it will require less
turpentine to thin it up.

Gold sizes, whether pale or dark, ought to have fully half a pound of
good gum copal to each gallon, when it is finished; and the best black
japan, to have half a pound of good gum, or upwards, besides the
quantity of asphaltum.

_Fine mastic, or picture varnish._--Put 5 pounds of fine picked gum
mastic into a new 4-gallon tin bottle; get ready 2 pounds of glass,
bruised as small as barley; wash it several times; afterwards dry it
perfectly, and put it into the bottle with 2 gallons of turpentine that
has settled some time; put a piece of soft leather under the bung; lay
the tin on a sack upon the counter, table, or any thing that stands
solid; begin to agitate the tin, smartly rolling it backward and
forward, causing the gum, glass, and turpentine, to work as if in a
barrel-churn for at least 4 hours, when the varnish may be emptied out
into any thing sufficiently clean, and large enough to hold it. If the
gum is not all dissolved, return the whole into the bottle, and agitate
as before, until all the gum is dissolved; then strain it through fine
thin muslin into a clean tin bottle: leave it uncorked, so that the air
can get in, but no dust; let it stand for 9 months, at least, before it
is used; for the longer it is kept, the tougher it will be, and less
liable to chill or bloom. To prevent mastic varnish from chilling, boil
1 quart of river sand with 2 ounces of pearl-ashes; afterwards wash the
sand three or four times with hot water, straining it each time; put the
sand on a soup-plate to dry, in an oven; and when it is of a good heat,
pour half a pint of hot sand into each gallon of varnish, and shake it
well for 5 minutes; it will soon settle, and carry down the moisture of
the gum and turpentine, which is the general cause of mastic varnish
chilling on paintings.

_Common mastic varnish._--Put as much gum mastic, unpicked, into the
gum-pot as may be required, and to every 2-3/4 pounds of gum pour in 1
gallon of cold turpentine; set the pot over a very moderate fire, and
stir it with the stirrer; be careful, when the steam of the turpentine
rises near the mouth of the pot, to cover it with the carpet, and carry
it out of doors, as the vapour is very apt to catch fire. A few minutes’
low heat will perfectly dissolve 8 pounds of gum, which will, with 4
gallons of turpentine, produce, when strained, 4-1/2 gallons of varnish;
to which add, while yet hot, 5 pints of pale turpentine varnish, which
improves the body and hardness of the mastic varnish.

_Crystal varnish_, may be made either in the varnish-house,
drawing-room, or parlour. Procure a bottle of Canada balsam, which can
be had at any druggist’s; draw out the cork, and set the bottle of
balsam at a little distance from the fire, turning it round several
times, until the heat has thinned it; then have something that will hold
as much as double the quantity of balsam; carry the balsam from the
fire, and, while fluid, mix it with the same quantity of good
turpentine, and shake them together until they are well incorporated: in
a few days the varnish is fit for use, particularly if it is poured into
a half-gallon glass or stone bottle, and kept in a gentle warmth. This
varnish is used for maps, prints, charts, drawings, paper ornaments,
&c.; and when made upon a larger scale, requires only warming the balsam
to mix with the turpentine.

_White hard spirit-of-wine varnish._--Put 5 pounds of gum sandarac into
a 4-gallon tin bottle, with 2 gallons of spirits of wine, 60 over proof,
and agitate it until dissolved, exactly as directed for the best mastic
varnish, recollecting, if washed glass is used, that it is convenient to
dip the bottle containing the gum and spirits into a copperful of hot
water every 10 minutes--the bottle to be immersed only 2 minutes at a
time--which will greatly assist the dissolving of the gum; but, above
all, be careful to keep a firm hold over the cork of the bottle,
otherwise the rarefaction will drive the cork out with the force of a
shot, and perhaps set fire to the place. The bottle, every time it is
heated, ought to be carried away from the fire; the cork should be eased
a little, to allow the rarefied air to escape; then driven tight, and
the agitation continued in this manner until all the gum is properly
dissolved; which is easily known by having an empty tin can to pour the
varnish into, until near the last, which is to be poured into a gallon
measure. If the gum is not all dissolved, return the whole into the
4-gallon tin, and continue the agitation until it is ready to be
strained, when every thing ought to be quite ready, and perfectly clean
and dry, as oily tins, funnels, strainers, or any thing damp, or even
cold weather, will chill and spoil the varnish. After it is strained
off, put into the varnish 1 quart of very pale turpentine varnish, and
shake and mix the two well together. Spirit varnishes should be kept
well corked: they are fit to use the day after being made.

_Brown hard spirit varnish_--is made by putting into a bottle 3 pounds
of gum sandarac, with 2 pounds of shellac, and 2 gallons of spirits of
wine, 60 over proof; proceeding exactly as before directed for the white
hard varnish, and agitating it when cold, which requires about 4 hours’
time, without any danger of fire; whereas, making any spirit varnish by
heat is always attended with danger. No spirit varnish ought to be made
either near a fire or by candle light. When this brown hard is strained,
add 1 quart of turpentine varnish, and shake and mix it well: next day
it is fit for use.

The _Chinese varnish_, comes from a tree, which grows in Cochin-China,
China, and Siam. It forms the best of all varnishes.

_Gold lacker._--Put into a clean 4-gallon tin, 1 pound of ground
turmeric, 1-1/2 ounces of powdered gamboge, 3-1/2 pounds of powdered gum
sandarac, 3/4 of a pound of shellac, and 2 gallons of spirits of wine.
After being agitated, dissolved, and strained, add 1 pint of turpentine
varnish, well mixed.

_Red spirit lacker._

  2     gallons of spirits of wine;
  1     pound of dragon’s blood;
  3     pounds of Spanish annotto;
  3-1/4 pounds of gum sandarac;
  2     pints of turpentine.
        Made exactly as the yellow gold lacker.

_Pale brass lacker._

  2 gallons of spirits of wine;
  3 ounces of Cape aloes, cut small;
  1 pound of fine pale shellac;
  1 ounce gamboge, cut small.
    No turpentine varnish. Made exactly as before.

But observe, that those who make lackers, frequently want some paler,
and some darker, and sometimes inclining more to the particular tint of
certain of the component ingredients. Therefore, if a 4-ounce phial of a
strong solution of each ingredient be prepared, a lacker of any tint can
be produced at any time.

_Preparation of linseed oil for making varnishes._--Put 25 gallons of
linseed oil into an iron or copper pot that will hold at least 30
gallons; put a fire under, and gradually increase the heat, so that the
oil may only simmer, for 2 hours; during that time the greatest part of
its moisture evaporates; if any scum arises on the surface, skim it off,
and put that aside for inferior purposes. Then increase the gradually,
and sprinkle in, by a little at a time, 3 lbs. of scale litharge, 3 lbs.
of good red lead, and 2 lbs. of Turkey umber, all well dried and free
from moisture. If any moist driers are added, they will cause the oil to
tumefy; and, at the same time, darken it, causing it to look opaque and
thick, ropy and clammy, and hindering it from drying and hardening in
proper time; besides, it will lie on the working painting like a piece
of bladder skin, and be very apt to rise in blisters. As soon as all the
driers are added to the oil, keep quietly stirring the driers from the
bottom of the pot; otherwise they will burn, which will cause the oil to
blacken and thicken before it is boiled enough. Let the fire be so
regulated that the oil shall only boil slowly for three hours from the
time all the driers were added; if it then ceases to throw up any scum,
and emits little or no smoke, it is necessary to test its temperature by
a few quill tops or feathers. Dip a quill top in the oil every two
minutes, for when the oil is boiled enough, the quill top will crackle
or curl up quite burnt; if so, draw out the fire immediately, and let
the oil remain in the pot at least from 10 to 24 hours, or longer if
convenient, for the driers settle much sooner when the oil is left to
cool in the pot, than when it is immediately taken out.

_Poppy oil._--Into four pints of pure soft water, put two ounces of
foreign white vitriol; warm the water in a clean copper pan, or glazed
earthen jar, until the vitriol is dissolved; pour the mixture into a
clean glass or stone bottle, large enough to contain three gallons; then
add to the solution of vitriol one gallon and a half of poppy oil, cork
and agitate the bottle regularly and smartly for at least two hours;
then pour out the contents into a wide earthenware dish: leave it at
rest for eight days, when the oil will be clean and brilliant on the
surface, and may be taken off with a spoon or flat skimmer, and put up
in a glass bottle and exposed to the light, which in a few weeks renders
the oil exceedingly limpid and colourless.

_Nut-oil, or oil of walnuts_, is extracted by expression; and that which
is extracted without heat, is certainly the most pale, pure, and
nutritive seasoning, and retains an exquisite taste of the fruit. That
designed for the arts is of inferior quality, and is plentifully
imported to us from France; the heat it undergoes in its torrefaction,
previous to its expression, disposes it to dry more quickly than that
expressed by the cold process; but, at the same time, the heat, though
it frees it from its unctuous quality, gives it more colour. When it has
been extracted by the cold process, it may be prepared in the same way
as directed for the poppy oil.

In the above article I have retained the workmen’s names--gum, white
vitriol, &c., instead of resin, sulphate of zinc, &c.


VEINS (_Filons_, Fr.; _Gänge_, Germ.); are the fissures or rents in
rocks, which are filled with peculiar mineral substances, most commonly
metallic ores.


VEIN STONES, or GANGUES, are the mineral substances which accompany, and
frequently enclose, the metallic ores.


VELLUM, is a fine sort of PARCHMENT, which see.


VELVET (_Velours_, Fr.; _Sammet_, Germ.); a peculiar stuff, the nature
of which is explained under FUSTIAN and TEXTILE FABRICS.


VENETIAN CHALK, is STEATITE.


VENUS, is the mythological name of copper.


VENTILATION, or the renewal of fresh air in stagnant places, is nowhere
exhibited to such advantage as in the coal mines of Northumberland and
Durham, where Mr. Buddle has carried well nigh to systematic perfection
the plan of coursing the air through the winding galleries, originally
contrived about the year 1760, by Mr. James Spedding, of Workington, the
ablest pitman of his day.[69] He converted the whole of the passages
into air-pipes, so to speak, drew the current of air from the downcast
pit, then traversed it up and down, and round about, through the several
sheths of the workings, so that no particular gallery was left without a
current of air. He thereby succeeded in actually expelling the noxious
gases from the mines; those demons, which in Germany, at no remote era,
were wont to be combated by the priests with impotent exorcisms or pious
frauds. Before Mr. Buddle introduced his improvements, he has known the
air to be led through a series of workings, thirty miles long, before it
made its exit. There is in every coal mine an experienced corps, called
wastemen, because they travel over the waste, or the exhausted regions,
who can tell at once, by the whistling sound which the air makes at the
crevices in certain partitions and doors, whether the ventilation be in
good condition or not. They hear these stoppings begin to _sing_ or
_call_, as they say, whenever an interruption takes place in any point
of the labyrinthian line. Another indication of something being wrong,
is when the doors get so heavy, that the boys in attendance upon them
find them difficult to shut or open. The instant such a defect is
discovered by any one, he cries aloud, “Holloa, there is something
wrong--the doors are calling!”

  [69] Mining engineers use the term _good pitman_, as admirals do _good
  seaman_, to denote a proficient in his calling.

In Mr. Spedding’s system, the whole of the return air came in one
current to his rarefying furnace (see letter C, _fig._ 1158.), whether
it was at the explosive point or not. This distribution was often
fraught with such danger, that a torrent of water had to be kept in
readiness, under the name of the waterfall, to be let down to extinguish
the fire in a moment. Many explosions at that time occurred, from the
furnaces below, and also down through tubes from the furnaces
above-ground.

[Illustration: 1158]

About the year 1807, Mr. Buddle had his attention intensely occupied
with this most important object, and then devised his plan of a divided
current, carrying that portion through the active furnace C, _fig._
1158., and the portion of the air from the _foul_ workings of the air
which, descending in the downcast pit A, coursed through the _clean_
workings, up the dumb furnace D, till it reached a certain elevation in
B, the upcast pit, above the fireplace. The pitmen had a great aversion,
however, at first, to adopt this plan, as they thought that the current
of air, by being split, would lose its ventilating power; but they were,
ere long, convinced by Mr. Buddle to the contrary. He divides the main
current into two separate streams, at the bottom of the pit A, as shown
by darts in the figure; the feathered ones, representing that part of
the pit in which the course of the current of air is free from explosive
mixture, or does not contain above one-thirtieth of carburetted
hydrogen, as indicated by its effect upon the flame of a candle. The
naked darts denote the portions of the mine where the air, being charged
to the firing point, is led off towards D, the dumb furnace, which
communicates with the hot upcast shaft, out of reach of the flame, and
thence derives its power of draught. By suitable alterations in the
stoppings (see the various transverse lines, and the crosses), any
portion of the workings may, by the agency of the furnace, be laid out
of, or brought within, the course of the vitiated current, at the
pleasure of the skilful mine-viewer; so that, if he found it necessary,
he could confine, by proper arrangements of his furnace, all the
vitiated current to a mere gas-pipe or drift, and direct it wholly
through the dumb furnace. During a practice of twenty years, Mr. Buddle
has not met with any accident in consequence of a defect in the
stoppings preventing the complete division of the air. The engineer has
it thus within his power to detach or insulate those portions of the
mine in which there is a great exudation of gas, from the rest; and,
indeed, he is continually making changes, borrowing and lending
currents, so to speak; sometimes laying one division or panel upon the
one air-course, and sometimes upon the other, just to suit the immediate
emergency. As soon as any district has ceased to be dangerous, by the
exhaustion of the gas-blowers, it is transferred from the foul to the
pure air course, where gunpowder may be safely used, as also candles,
instead of Davy’s lamps, which give less light.

The quantity of air put down into the Wallsend colliery, at the time of
the last dreadful accident, 18th June, 1835, was not less than 5000
cubic feet per minute, whence it has been justly inferred that the
explosion was caused by the rashness of a wasteman carrying a light
through a door into a foul drift.

Till the cutting out of the pillars commences (see the right end of the
diagram), the ventilation of the several passages, boards, &c., may be
kept perfect, supposing the working extended no further than _a_, or
_b_; because, as long as there are pillars standing, every passage may
be converted into an air-conduit, for leading a current of air in any
direction, either to C, the burning, or D, the dumb furnace. But the
first pillar that is removed deranges the ventilation at that spot, and
takes away the means of carrying the air into the further recess towards
_c_. In taking out the pillars, the miners always work to windward, that
is to say, against the stream of air; so that, whatever gas may be
evolved, shall be immediately carried off from the people at work. When
a range of pillars has been removed, as at _d_, _e_, _f_, no power
remains of dislodging the gas from the section of the mine beyond _a_,
_b_; and as the pillars are successively cut away to the left hand of
the line _a_, _b_, the size of the _goaf_, or void, is increased. This
vacuity is a true gas-holder, or reservoir, continually discharging
itself at the points _g_, _h_, _i_, into the circulating current, to be
carried off by the gas-pipe drift at the dumb furnace, but not to be
suffered ever to come in contact with flame of any description. The next
range of working, is the line of pillars to the left of _a_, _b_; the
coal having been entirely cleared out of the space to the right, where
the place of the pillars is marked by dotted lines. The roof in the
waste soon falls down, and gets fractured up to the next seam of coal,
called the yard-coal seam, which, abounding in gas, sends it down in
large quantities, and keeps the immense gasometer, or goaf below,
continually replenished. See STOVE.


VERATRINE, is a vegetable alkali, of a poisonous nature, extracted from
the seeds of the _Veratrum sabadilla_, the roots of the _Veratrum
album_, or white hellebore, and of _Colchicum autumnale_, or meadow
saffron, in which plants it exists combined chiefly with gallic acid. It
is obtained in the form of a white powder. It has an acrid, burning
taste, but without any bitterness; it has no smell; but when snuffed
into the nostrils, it excites violent and dangerous sneezing. It melts
at a heat of 122° F., and concretes, on cooling, into a transparent
yellowish mass. It restores the blue colour of reddened litmus paper. It
is hardly soluble in water or ether, but abundantly in alcohol. It
consists of--carbon 66·75, hydrogen 8·54, nitrogen 5·04, and oxygen
19·60. Its saline compounds have an acrid and burning taste. Veratrine
resembles strychnine and brucine, in its effects upon living bodies,
producing tetanus and death in a moderate dose; notwithstanding which,
it has been prescribed by some of our poison doctors, especially mixed
with hog’s lard, in the form of frictions on the forehead, for nervous
maladies; but seldom, I believe, with any good effects.


VERDIGRIS. (_Vert-de-gris_, Fr.; _Grünspan_, Germ.) The copper used in
this manufacture, is formed into round sheets, from 20 to 25 inches
diameter, by one twenty-fourth of an inch in thickness. Each sheet is
then divided into oblong squares, from 4 to 6 inches in length, by 3
broad; and weighing about 4 ounces. They are separately beaten upon an
anvil, to smooth their surfaces, to consolidate the metal, and to free
it from scales. The refuse of the grapes, after the extraction of their
juice, formerly thrown on to the dunghill, is now preserved for the
purpose of making verdigris. It is put loosely into earthen vessels,
which are usually 16 inches high, 14 in diameter at the widest part, and
about 12 at the mouth. The vessels are then covered with lids, which are
surrounded by straw mats. In this situation the materials soon become
heated, and exhale an acid odour; the fermentation beginning at the
bottom of the cask, and gradually rising till it actuate the whole mass.
At the end of two or three days, the manufacturer removes the fermenting
materials into other vessels, in order to check the process, lest
putrefaction should ensue. The copper plates, if new, are now prepared,
by rubbing them over with a linen cloth dipt in a solution of verdigris;
and they are laid up alongside of one another to dry. If the plates are
not subjected to this kind of preparation, they will become black,
instead of green, by the first operation. When the plates are ready, and
the materials in a fermenting state, one of them is put into the
earthern vessel for 24 hours, in order to ascertain whether it be a
proper period to proceed to the remaining part of the process. If, at
the end of this period, the plate be covered with an uniform green
layer, concealing the whole copper, every thing is right; but if, on the
contrary, liquid drops hang on the surface of the metal, the workmen say
the plates are _sweating_, and conclude that the heat of the fermented
mass has been inadequate; on which account another day is allowed to
pass before making a similar trial. When the materials are finally found
to be ready, the strata are formed in the following manner. The plates
are laid on a horizontal wooden grating, fixed in the middle of a vat,
on whose bottom a pan full of burning charcoal is placed, which heats
them to such a degree, that the women who manage this work are obliged
to lay hold of them frequently with a cloth when they lift them out.
They are in this state put into earthern vessels, in alternate strata
with the fermented materials, the uppermost and undermost layers being
composed of the expressed grapes. The vessels are covered with their
straw mats, and left at rest. From 30 to 40 pounds of copper are put
into one vessel.

At the end of 10, 12, 15, or 20 days the vessels are opened, to
ascertain, by the materials having become white, if the operation be
completed.

Detached glossy crystals will be perceived on the surface of the plates;
in which case the grapes are thrown away, and the plates are placed
upright in a corner of the verdigris cellar, one against the other, upon
pieces of wood laid on the ground. At the end of two or three days they
are moistened by dipping in a vessel of water, after which they are
replaced in their former situation, where they remain seven or eight
days, and are then subjected to momentary immersion, as before. This
alternate moistening and exposure to air is performed six or eight
times, at regular intervals of about a week. As these plates are
sometimes dipped into damaged wine, the workmen term these immersions,
_one wine_, _two wines_, &c.

By this treatment, the plates swell, become green, and covered with a
stratum of verdigris, which is readily scraped off with a knife. At each
operation every vessel yields from five to six pounds of verdigris, in a
_fresh_ or _humid_ state; which is sold to wholesale dealers, who dry it
for exportation. For this purpose, they knead the paste in wooden
troughs, and then transfer it to leathern bags, a foot and a half long,
and ten inches in diameter. These bags are exposed to the sun and air
till the verdigris has attained a sufficient degree of hardness. It
loses about half its weight in this operation; and it is said to be
knife-proof, when this instrument, plunged through the leathern bag,
cannot penetrate the loaf of verdigris.

The manufacture of verdigris at Montpellier is altogether domestic. In
most wine farm-houses there is a verdigris cellar; and its principal
operations are conducted by the females of the family. They consider the
forming the strata, and scraping off the verdigris, the most troublesome
part. Chaptal says that this mode of making verdigris would admit of
some improvements: for example, the acetification requires a warmer
temperature than what usually arises in the earthen vessels; and the
plates, when set aside to generate the coat of verdigris, require a
different degree of heat and moisture from that requisite for the other
operations.

Verdigris is a mixture of the crystallized acetate of copper and the
sub-acetate, in varying proportions. According to Vauquelin’s
researches, there are three compounds of oxide of copper and acetic
acid; 1. a subacetate, insoluble in water, but decomposing in that
fluid, at common temperatures changing into peroxide and acetate; 2. a
neutral acetate, the solution of which is not altered at common
temperatures, but is decomposed by ebullition, becoming peroxide and
superacetate; and, 3. superacetate, which in solution is not
decomposed, either at common temperatures or at the boiling point; and
which cannot be obtained in crystals, except by slow spontaneous
evaporation, in air or _in vacuo_. The first salt, in the dry state,
contains 66·51 of oxide; the second, 44·44; and the third, 33·34.

Mr. Phillips has given the following analyses of French and English
verdigris; _Annals of Philosophy_, No. 21.--

                       French       English
                     Verdigris.    Verdigris.
  Acetic acid           29·3         29·62
  Peroxide of copper    43·5         44·25
  Water                 25·2         25·51
  Impurity               2·0          0·62
                       -----        ------
                       100·0        100·00

_Distilled verdigris_, as it was long erroneously called, is merely a
_binacetate_ or superacetate of copper, made by dissolving, in a copper
kettle, one part of verdigris in two of distilled vinegar; aiding the
mutual action by slight heat and agitation with a wooden spatula. When
the liquor has taken its utmost depth of colour, it is allowed to
settle, and the clear portion is decanted off into well glazed earthen
vessels. Fresh vinegar is poured on the residuum, and if its colour does
not become deep enough, more verdigris is added. The clear and saturated
solution is then slowly evaporated, in a vessel kept uniformly filled,
till it acquires the consistence of syrup, and shows a pellicle on its
surface; when it is transferred into glazed earthen pans, called _oulas_
in the country. In each of these dishes, two or three sticks are placed,
about a foot long, cleft till within two inches of their upper end, and
having the base of the cleft kept asunder by a bit of wood. This kind of
pyramid is suspended by its summit in the liquid. All these vessels are
transported into crystallizing rooms, moderately heated with a stove,
and left in the same state for 15 days, taking care to maintain an
uniform temperature. Thus are obtained very fine groups of crystals of
acetate of copper, clustered round the wooden rods; on which they are
dried, taken off, and sent into the market. They are distinctly
rhomboidal in form, and of a lively deep blue colour. Each cluster of
crystals weighs from five to six pounds; and, in general, their total
weight is equal to about one-third of the verdigris employed.

The crystallized binacetate of commerce consists, by my analysis,
of--acetic acid, 52; oxide of copper, 39·6; water, 8·4, in 100. I have
prepared crystals which contain no water. There is a triple acetate of
copper and lime, which resembles distilled verdigris in colour. It was
manufactured pretty extensively in Scotland some years ago, and fetched
a high price, till I published an analysis of it in the Edinburgh
Philosophical Journal. It is much inferior, for all uses in the arts, to
the proper binacetate.


VERDITER, or BLUE VERDITER. This is a precipitate of oxide of copper
with lime, made by adding that earth, in its purest state, to the
solution of nitrate of copper, obtained in quantities by the refiners,
in parting gold and silver from copper by nitric acid. The cupreous
precipitate must be triturated with lime, after it is nearly dry, to
bring out the fine velvety blue colour. The process is delicate, and
readily misgives in unskilful hands.

The _cendres bleues en pâte_ of the French, though analogous, are in
some respects a different preparation. To make it, dissolve sulphate of
copper in hot water, in such proportions that the liquid may have a
density of 1·3. Take 240 pound measures of this solution, and divide it
equally into 4 open-headed casks; add to each of these 45 pound measures
of a boiling-hot solution of muriate of lime, of specific gravity 1·317,
whereby a double decomposition will ensue; with the formation of muriate
of copper and sulphate of lime, which precipitates. It is of consequence
to work the materials well together at the moment of mixture, to prevent
the precipitate agglomerating in unequal masses. After leaving it to
settle for 12 hours, a small quantity of the clear liquor may be
examined, to see whether the just proportions of the two salts have been
employed, which is done by adding either sulphate of copper or muriate
of lime. Should either cause much precipitation, some of the other must
be poured in till the equivalent decomposition be accomplished; though
less harm results from an excess of sulphate of copper than of muriate
of lime.

The muriate of copper is to be decanted from the subsided gypsum, which
must be drained and washed in a filter; and these blue liquors are to be
added to the stronger; and the whole distributed, as before, into 4
casks; composing in all 670 pound measures of a green liquor, of 1·151
specific gravity.

Meanwhile, a magma of lime is to be prepared as follows:--100 pounds of
quicklime are to be mixed up with 300 pounds of water, and the mixture
is to be passed through a wire-gauze sieve, to separate the stony and
sandy particles, and then to be ground in a proper mill to an impalpable
paste. About 70 or 80 pounds of this mixture (the beauty of the colour
is inversely as the quantity of lime) are to be distributed in equal
portions between the four casks, strongly stirring all the time with a
wooden spatula. It is then left to settle, and the limpid liquor is
tested by ammonia, which ought to occasion only a faint blue tinge; but
if the colour be deep blue, more of the lime paste must be added. The
precipitate is now to be washed by decantation, employing for this
purpose the weak washings of a former operation; and it is lastly to be
drained and washed on a cloth filter. The proportions of material
prescribed above, furnish from 500 to 540 pounds of green paste.

Before making further use of this paste, the quantity of water present
in it must be determined by drying 100 or 200 grains. If it contain 27
per cent. of dry matter, 12 pounds of it may be put into a wooden bucket
(and more or less in the ratio of 12 to to 27 per cent.) capable of
containing 17-1/2 pints; a pound (measure) of the lime paste is then to
be rapidly mixed into it; immediately afterwards, a pint and a quarter
of a watery solution of the pearlash of commerce, of spec. grav. 1·114,
previously prepared; and the whole mixture is to be well stirred, and
immediately transferred to a colour-mill. The quicker this is done, the
more beautiful is the shade.

On the other hand, two solutions must have been previously made ready,
one of sal-ammoniac (4 oz. troy dissolved in 3-1/2 pints of water), and
another of sulphate of copper (8 oz. troy dissolved in 3-1/2 pints of
water).

When the paste has come entirely through the mill, it is to be quickly
put into a jar, and the two preceding solutions are to be simultaneously
poured into it; when a cork is to be inserted, and the jar is to be
powerfully agitated. The cork must now be secured with a fat lute. At
the end of four days this jar and three of its fellows are to be emptied
into a large hogshead nearly full of clear water, and stirred well with
a paddle. After repose, the supernatant liquid is run off; when it is
filled up again with water, and elutriated several times in succession,
till the liquid no longer tinges turmeric paper brown. The deposit may
be then drained on a cloth filter. The pigment is sold in the state of a
paste; and is used for painting, or printing paper-hangings for the
walls of apartments.

The above prescribed proportions furnish the superfine blue paste: for
the second quality, one-half more quicklime paste is used; and for the
third, double of the lime and sal ammoniac; but the mode of preparation
is in every case the same.

This paste may be dried into a blue powder, or into crayons for
painters, by exposing it on white deals to a very gentle heat in a shady
place. This is called _cendres bleues en pierre_.


VERDITER, or BREMEN GREEN. This pigment is a light powder, like
magnesia, having a blue or bluish green colour. The first is most
esteemed. When worked up with oil or glue, it resists the air very well;
but when touched with lime, it is easily affected, provided it has not
been long and carefully dried. A strong heat deprives it of its lustre,
and gives it a brown or blackish-green tint.

The following is, according to M. J. G. Gentele, the process of
fabrication in Bremen, Cassel, Eisenach, Minden, &c.:--

_a._ 225 lbs. of sea salt, and 222 lbs. of blue vitriol, both free from
iron, are mixed in the dry state, then reduced between mill-stones with
water to a thick homogeneous paste.

_b._ 225 lbs. of plates of old copper are cut by scissors into bits of
an inch square, then thrown and agitated in a wooden tub containing two
lbs. of sulphuric acid, diluted with a sufficient quantity of water, for
the purpose of separating the impurities; they are afterwards washed
with pure water in casks made to revolve upon their axes.

_c._ The bits of copper being placed in oxidation-chests, along with the
magma of common salt and blue vitriol previously prepared in strata of
half an inch thick, they are left for some time to their mutual
reaction. The above chests are made of oaken planks joined without iron
nails, and set aside in a cellar, or other place of moderate
temperature.

The saline mixture, which is partially converted into sulphate of soda
and chloride of copper, absorbs oxygen from the air, whereby the
metallic copper passes into a hydrated oxide, with a rapidity
proportioned to the extent of the surfaces exposed to the atmosphere. In
order to increase this exposure, during the three months that the
process requires, the whole mass must be turned over once every week,
with a copper shovel, transferring it into an empty chest alongside, and
then back into the former one.

At the end of three months, the corroded copper scales must be picked
out, and the saline particles separated from the slimy oxide with the
help of as little water as possible.

_d._ This oxidized _schlam_, or mud, is filtered, then thrown, by means
of a bucket containing 30 pounds, into a tub, where it is carefully
divided or comminuted.

_e._ For every six pailfuls of _schlam_ thus thrown into the large tub,
12 pounds of muriatic acid, at 15° Baumé, are to be added; the mixture
is to be stirred, and then left at rest for 24 or 36 hours.

_f._ Into another tub, called the blue back, there is to be introduced,
in like manner, for every six pailfuls of the acidified _schlam_, 15
similar pailfuls of a solution of colourless clear caustic alkali, at
19° Baumé.

_g._ When the back (_e_) has remained long enough at rest, there is to
be poured into it a pail of pure water for every pail of _schlam_.

_h._ When all is thus prepared, the set of workmen who are to empty the
back (_e_), and those who are to stir (_f_), must be placed alongside of
each. The first set transfer the _schlam_ rapidly into the latter back;
where the second set mix and agitate it all the time requisite to
convert the mass into a consistent state, and then leave it at rest from
36 to 48 hours.

The whole mass is to be now washed; with which view it is to be stirred
about with the affusion of water, allowed to settle, and the supernatant
liquor is drawn off. This process is to be repeated till no more traces
of potash remain among the blue. The deposit must be then thrown upon a
filter, where it is to be kept moist, and exposed freely to the air. The
pigment is now squeezed in the filter-bags, cut into bits, and dried in
the atmosphere, or at a temperature not exceeding 78° Fahr. It is only
after the most complete desiccation that the colour acquires its
greatest lustre.


VERMICELLI, is a paste of wheat flour, drawn out and dried in slender
cylinders, more or less tortuous, like worms, whence the Italian name.
The _gruau_ of the French is wheat coarsely ground, so as to free it
from the husk; the hardest and whitest part, being separated by sifting,
is preferred for making the finest bread. When this _gruau_ is a little
more ground, and the dust separated from it by the boulting-machine, the
granular substance called _semoule_ is obtained, which is the basic of
the best pastes. The softest and purest water is said to be necessary
for making the most plastic vermicelli dough; 12 pounds of it being
usually added to 50 pounds of _semoule_. It is better to add more
_semoule_ to the water, than water to the _semoule_, in the act of
kneading. The water should be hot, and the dough briskly worked while
still warm. The Italians pile one piece of this dough upon another, and
then tread it well with their feet for two or three minutes. They
afterwards work it for two hours with a powerful rolling-pin, a bar of
wood from 10 to 12 feet long, larger at the one end than the other,
having a sharp cutting edge at the extremity, attached to the large
kneading-trough.

When the dough is properly prepared, it is reduced to thin ribands,
cylinders, or tubes, to form vermicelli and macaroni of different kinds.
This operation is performed by means of a powerful press. This is
vertical, and the iron plate or follower carried by the end of the screw
fits exactly into a cast-iron cylinder, called the _bell_, like a
sausage-machine, of which the bottom is perforated with small holes, of
the shape and size intended for the vermicelli. The _bell_ being filled,
and warmed with a charcoal fire to thin the dough into a paste, this is
forced slowly through the holes, and is immediately cooled and dried by
a fanner as it protrudes. When the threads or fillets have acquired the
length of a foot, they are grasped by the hand, broken off, and twisted,
while still flexible, into any desired shape upon a piece of paper.

The macaroni requires to be made of a less compact dough than the
vermicelli. The former is forced through the perforated bottom, usually
in fillets, which are afterwards formed into tubes by joining their
edges together before they have had time to become dry. The _lazagnes_
are macaroni left in the fillet or riband shape.


VERMILLION, or _Cinnabar_, is a compound of mercury and sulphur in the
proportion of 100 parts of the former to 16 of the latter, which occurs
in nature as a common ore of quicksilver, and is prepared by the chemist
as a pigment, under the name of Vermillion. It is, properly speaking, a
bisulphuret of mercury. This artificial compound being extensively
employed, on account of the beauty of its colour, in painting, for
making red sealing-wax, and other purposes, is the object of an
important manufacture. When vermillion is prepared by means of
sublimation, it concretes in masses of considerable thickness, concave
on one side, convex on the other, of a needle-form texture; brownish-red
in the lump, but when reduced to powder of a lively red colour. On
exposure to a moderate heat, it evaporates without leaving a residuum,
if it be not contaminated with red lead; and at a higher heat, it takes
fire, and burns entirely away, with a blue flame.

Holland long kept a monopoly of the manufacture of vermillion, from
being alone in possession of the art of giving it a fine flame colour.
Meanwhile the French chemists examined this product with great care,
under an idea that the failure of other nations to rival the Dutch,
arose from ignorance of its true composition; some, with Berthollet,
imagined that it contained a little hydrogen; and others, with Fourcroy,
believed that the mercury contained in it was oxidized; but, eventually,
Seguin proved that both of these opinions were erroneous; having
ascertained, on the one hand, that no hydrogenous matter was given out
in the decomposition of cinnabar, and on the other that sulphur and
mercury, by combining, were transformed into the red sulphuret in close
vessels, without the access of any oxygen whatever. It was likewise
supposed that the solution of the problem might be found in the
difference of composition between the red and black sulphurets of
mercury; and many conjectures were made with this view, the whole of
which were refuted by Seguin. He demonstrated, in fact, that a mere
change of temperature was sufficient to convert the one sulphuret into
the other, without occasioning any variation in the proportion of the
two elements. Cinnabar, moderately heated in a glass tube, is
convertible into ethiops, which in its turn is changed into cinnabar by
exposing the tube to a higher temperature; and thence he was led to
conclude that the difference between these two sulphurets was owing
principally to the state of the combination of the constituents. It
would seem to result, from all these researches, that cinnabar is only
an intimate compound of pure sulphur and mercury, in the proportions
pointed out by analysis; and it is therefore reasonable to conclude,
that in order to make fine vermillion, it should be sufficient to effect
the union of its elements at a high enough temperature, and to exclude
the influence of all foreign matters; but, notwithstanding these
discoveries, the art of making good vermillion is nearly as much a
mystery as ever. M. Seguin, indeed, announced in his Memoirs, that he
had succeeded in obtaining, in his laboratory, as good a cinnabar as
that of Holland, and at a remunerative price; but whatever truth may be
in this assertion, or however much the author may have been excited by
the love of honour and profit, no manufacture on the great scale sprung
up under his auspices. France is still as tributary as ever to foreign
nations for this chemical product. At an exposition some years ago,
indeed, a sample of good French vermillion was brought forward to prove
that the problem was nearly solved; but that it is not so completely,
may be inferred from the silence on this subject in M. Dupin’s report of
the last exposition, in 1834, where we see so many chemical trifles
honoured with eulogiums and medals by the judges of the show. The
English vermillion is now most highly prized by the French manufacturers
of sealing-wax.

M. Tuckert, apothecary of the Dutch court, published, long ago, in the
_Annales de Chimie_, vol. iv., the best account we yet have of the
manufacture of vermillion in Holland; one which has been since verified
by M. Payssé, who saw the process practised on the great scale with
success.

“The establishment in which I saw, several times, the fabrication of
sublimed sulphuret of mercury,” says M. Tuckert, “was that of Mr. Brand,
at Amsterdam, beyond the gate of Utrecht; it is one of the most
considerable in Holland, producing annually, from three furnaces, by
means of four workmen, 48,000 pounds of cinnabar, besides other
mercurial preparations. The following process is pursued here:--

“The ethiops is first prepared by mixing together 150 pounds of sulphur,
with 1080 pounds of pure mercury, and exposing this mixture to a
moderate heat in a flat polished iron pot, one foot deep, and two feet
and a half in diameter. It never takes fire, provided the workman
understands his business. The black sulphuret, thus prepared, is ground,
to facilitate the filling with it of small earthen bottles capable of
holding about 24 ounces of water; from 30 to 40 of which bottles are
filled beforehand, to be ready when wanted.

“Three great subliming pots or vessels, made of very pure clay and sand,
have been previously coated over with a proper lute, and allowed to dry
slowly. These pots are set upon three furnaces bound with iron hoops,
and they are covered with a kind of iron dome. The furnaces are
constructed so that the flame may freely circulate and play upon the
pots, over two-thirds of their height.

“The subliming vessels having been set in their places, a moderate fire
is kindled in the evening, which is gradually augmented till the pots
become red. A bottle of the black sulphuret is then poured into the
first in the series, next into the second and third, in succession; but
eventually, two, three, or even more, bottles may be emptied in at once;
this circumstance depends on the stronger or weaker combustion of the
sulphuret of mercury thus projected. After its introduction, the flame
rises 4 and sometimes 6 feet high; when it has diminished a little, the
vessels are covered with a plate of iron, a foot square, and an inch and
a half thick, made to fit perfectly close. In this manner, the whole
materials which have been prepared are introduced, in the course of 34
hours, into the three pots; being for each pot, 360 pounds of mercury,
and 50 of sulphur; in all, 410 pounds.”

The degree of firing is judged of, from time to time, by lifting off the
cover; for if the flame rise several feet above the mouth of the pot,
the heat is too great; if it be hardly visible, the heat is too low. The
proper criterion being a vigorous flame playing a few inches above the
vessel. In the last of the 36 hours’ process, the mass should be
dexterously stirred up every 15 or 20 minutes, to quicken the
sublimation. The subliming pots are then allowed to cool, and broken to
pieces in order to collect all the vermillion encrusted within them;
and which usually amounts to 400 lbs., being a loss of only 60 on each
vessel. The lumps are to be ground along with water between horizontal
stones, elutriated, passed through sieves, and dried. It is said that
the rich tone of the Chinese vermillion may be imitated by adding to the
materials for subliming one per cent. of sulphuret of antimony, and by
digesting the ground article first in a solution of sulphuret of
potassa, and, finally, in diluted muriatic acid.

The humid process of Kirchoff has of late years been so much improved,
as to furnish a vermillion quite equal in brilliancy to the Chinese. The
following process has been recommended. Mercury is triturated for
several hours with sulphur, in the cold, till a perfect ethiops is
formed; potash lye is then added, and the trituration is continued for
some time. The mixture is now heated in iron vessels, with constant
stirring at first, but afterwards only from time to time. The
temperature must be kept up as steadily as possible at 130° Fahr.,
adding fresh supplies of water as it evaporates. When the mixture which
was black, becomes, at the end of some hours, brown-red, the greatest
caution is requisite, to prevent the temperature from being raised above
114°, and to preserve the mixture quite liquid, while the compound of
sulphur and mercury should always be pulverulent. The colour becomes
red, and brightens in its hue, often with surprising rapidity. When the
tint is nearly fine, the process should be continued at a gentler heat,
during some hours. Finally, the vermillion is to be elutriated, in order
to separate any particles of running mercury. The three ingredients
should be very pure. The proportion of product varies with that of the
constituents, as we see from the following results of experiments, in
which 300 parts of mercury were always employed, and from 400 to 450 of
water:--

  Sulphur.    Potash.   Vermillion obtained.
    114         75             330
    115         75             331
    120        120             321
    150        152             382
    120        180             245
    100        180             244
     60        180             142

The first proportions are therefore the most advantageous; the last,
which are those of M. Kirchoff himself, are not so good.

Brunner found that 300 parts of quicksilver, 114 of sulphur, 75 of
caustic potassa, and from 400 to 450 of water, form very suitable
proportions for the moist process; that the best temperature was 113°
F.; and that 122° was the highest limit of heat compatible with the
production of a fine colour.

The theory of this process is by no means clear. We may suppose that a
sulphuret of potassium and mercury is first formed, which is eventually
destroyed, in proportion as the oxygen of the air acts upon the
sulphuret of potassium itself. There may also be produced some
hyposulphite of mercury, which, under the same influence, would be
transformed into sulphuret of mercury and sulphate of potash.

Sulphuret of potassium and mercury furnish also vermillion, but it is
not beautiful. Red oxide of mercury, calomel, turbith mineral, and the
soluble mercury of Hahnemann, treated with the sulphuret of potassium,
or the hydrosulphuret of ammonia, are all capable of giving birth to
vermillion by the humid way.

The vermillion of commerce is often adulterated with red lead,
brickdust, dragon’s blood, and realgar. The first two, not being
volatile, remain when the vermillion is heated to its subliming point;
the third gives a red tincture to alcohol; the fourth exhales its
peculiar garlic smell with heat; and when calcined in a crucible with
carbonate of soda, and nitre in excess, affords arsenic acid, which may
be detected by the usual chemical tests.


VINEGAR MANUFACTORY, BY MALT. Annual produce, 100,000 gallons.

                   _Expenses for One Month._                _£   s.  d._
  Cost of material and fuel for 8,333 gallons,
  at 8-3/4_d._                                              303  16   2
  Wages to 8 workmen, at 25_s._ per week                     40   0   0
  Salaries to clerks, manager, and traveller                 83   6   8
  Travelling expensesat                                      30   0   0
  Three horses’ keep                                          7  10   0
  Rent and taxes                                             25   0   0
                                                            -----------
                                                         _£_489  12  10
                                                            -----------

  Expenses for 5 months, at 489_l._ 12_s._ 10_d._          2448   4   2
  Duty on 41,665 gallons, at 2_d._                          347   4   2
  Stock of utensils                                        1500   0   0
                                                           ------------
                                                        _£_4295   8   4
                                                           ------------

  Produce of 100,000 gallons, at 1_s._ 8_d._            _£_8333   6   8
  Expenses for 12 months, at 489_l._
                           12_s._ 10_d._  _£_5875 18 0
  Duty on 100,000 gallons,
  at 2_d._                                    833  6 8
  Interest on capital, 4295_l._ 8_s._ 4_d._   214  4 5
                                             ---------
                                                           6923   9   1
                                                           ------------
  Net profit                                            _£_1409  17   7
                                                           ------------

See ACETIC ACID.


VIOLET DYE, is produced by a mixture of red and blue colouring-matters,
which are applied in succession. Silk is dyed a fugitive violet with
either archil or brazil wood; but a fine fast violet, first by a crimson
with cochineal, without tartar or tin mordant, and after washing, it is
dipped in the indigo vat. A finish is sometimes given with archil. A
violet is also given to silk, by passing it through a solution of
verdigris, then through a bath of logwood, and, lastly, through alum
water. A more beautiful violet may be communicated by passing the alumed
silk through a bath of brazil wood, and after washing it in the river,
through a bath of archil.

To produce violets on printed calicoes, a dilute acetate of iron is the
mordant, and the dye is madder. The mordanted goods should be well
dunged.

A good process for dyeing cottons violet, is--first, to gall, with 18 or
20 pounds of nut-galls for every 100 pounds of cotton; second, to pass
the stuff; still hot, through a mordant composed of--alum, 10 pounds;
iron-liquor, at 1-1/2° B., and sulphate of copper, each 5 or 6 pounds;
water, from 24 to 28 gallons; working it well, with alternate steeping,
squeezing, airing, dipping, squeezing, and washing; third, to madder,
with its own weight of the root; and fourth, to brighten with soap. If
soda be used at the end, instead of soap, the colour called _prune de
monsieur_ will be produced; and by varying the doses of the ingredients,
a variety of violet tints may be given.

The best violets are produced by dyeing yarn or cloth which has been
prepared with oil as for the Turkey-red process. See MADDER.

For the violet _pruneau_, a little nitrate of iron is mixed with the
alum mordant, which makes a black; but this is changed into _violet
pruneau_, by a madder bath, followed by a brightening with soap.


VITRIFIABLE COLOURS; see ENAMELS, PASTES, POTTERY, and STAINED GLASS.


VITRIOL, from _vitrum_, glass, is the old chemical, and still the vulgar
appellation of sulphuric acid, and of many of its compounds, which in
certain states have a glassy appearance: thus--

Vitriolic acid, or oil of vitriol, is sulphuric acid; blue vitriol, is
sulphate of copper; green vitriol, is green sulphate of iron; vitriol of
Mars, is red sulphate of iron; and white vitriol, is sulphate of zinc.




W.


WACKE, is a massive mineral, intermediate between claystone and basalt.
It is of a greenish-gray colour; vesicular in structure; dull, opaque;
streak shining; soft, easily frangible; spec. grav. 2·55 to 2·9; it
fuses like basalt.


WADD, is the provincial name of plumbago in Cumberland; and also of an
ore of manganese in Derbyshire, which consists of the peroxide of that
metal, associated with nearly its own weight of oxide of iron.


WADDING (_Ouate_, Fr.; _Watte_, Germ.); is the spongy web which serves
to line ladies’ pelisses, &c. _Ouate_, or _Wat_, was the name originally
given to the glossy downy tufts found in the pods of the plant commonly
called _Apocyn_, and by botanists _Asclepias syriaca_, which was
imported from Egypt and Asia Minor for the purpose of stuffing cushions,
&c. Wadding is now made with a lap or fleece of cotton prepared by the
carding-engine (see _Carding_, COTTON MANUFACTURE), which is applied to
tissue paper by a coat of size, made by boiling the cuttings of
hare-skins, and adding a little alum to the gelatinous solution. When
two laps are glued with their faces together, they form the most downy
kind of wadding.


WAFERS. There are two manners of manufacturing wafers: 1, with wheat
flour and water, for the ordinary kind; and 2, with gelatine. 1. A
certain quantity of fine flour is to be diffused through pure water, and
so mixed as to leave no clotty particles. This thin pap is then coloured
with one or other of the matters to be particularly described under the
second head; and which are, vermillion, sulphate of indigo, and gamboge.
The pap is not allowed to ferment, but must be employed immediately
after it is mixed. For this purpose a tool is employed, consisting of
two plates of iron, which come together like pincers or a pair of
tongs, leaving a certain small definite space betwixt them. These plates
are first slightly heated, greased with butter, filled with the pap,
closed, and then exposed for a short time to the heat of a charcoal
fire. The iron plates being allowed to cool, on opening them, the thin
cake appears dry, solid, brittle, and about as thick as a playing-card.
By means of annular punches of different sizes, with sharp edges, the
cake is cut into wafers. 2. The transparent wafers are made as
follows:--

Dissolve fine glue, or isinglass, in such a quantity of water, that the
solution, when cold, may be consistent. Let it be poured hot upon a
plate of mirror glass, (previously warmed with steam, and slightly
greased,) which is fitted in a metallic frame, with edges just as high
as the wafers should be thick. A second plate of glass, heated and
greased, is laid on the surface, so as to touch every point of the
gelatine, resting on the edges of the frame. By this pressure, the thin
cake of gelatine is made perfectly uniform. When the two plates of glass
get cold, the gelatine becomes solid, and may easily be removed. It is
then cut with proper punches into discs of different sizes.

The colouring-matters ought not to be of an insalubrious kind.

For red wafers, carmine is well adapted, when they are not to be
transparent; but this colour is dear, and can be used only for the finer
kinds. Instead of it, a decoction of brazil wood, brightened with a
little alum, may be employed.

For yellow, an infusion of saffron or turmeric has been prescribed; but
a decoction of weld, fustic, or Persian berries, might be used.

Sulphate of indigo, partially saturated with potash, is used for the
blue wafers; and this mixed with yellow, for the greens. Some recommend
the sulphate to be nearly neutralized with chalk, and to treat the
liquor with alcohol, in order to obtain the best blue dye for wafers.

Common wafers are, however, coloured with the substances mentioned at
the beginning of the article; and for the cheaper kinds, red lead is
used instead of vermillion, and turmeric instead of gamboge.


WALNUT HUSKS, or PEELS (_Brout des noix_, Fr.); are much employed by the
French dyers for rooting or giving dun colours.


WARP (_Chaine_, Fr.; _Kette_, _Auschweif_, _Zettel_, Germ.); is the name
of the longitudinal threads or yarns, whether of cotton, linen, silk, or
wool, which being decussated at right angles by the woof or weft
threads, form a piece of cloth. The warp yarns are parallel, and
continuous from end to end of the web. See WEAVING, for a description of
the _warping-mill_.


WASH, is the fermented wort of the distiller.


WASHING. See BLEACHING, and SCOURING.


WATERING OF STUFFS (_Moirage_, Fr.); is a process to which silk and
other textile fabrics are subjected, for causing them to exhibit a
variety of undulated reflections, and plays of light. It is produced by
sprinkling water upon the goods, and then passing them through a
calender, either with cold or hot rollers, plain or variously indented.


WATER-PROOF CLOTH. See CAOUTCHOUC, and GELATINE.

A patent was obtained, in August, 1830, by Mr. Thomas Hancock, for
rendering textile fabrics impervious to water and air, by spreading the
liquid juice of the caoutchouc tree upon the surfaces of the goods, and
then exposing them to the air to dry. It does not appear that this
project has been realized in our manufactures.

Mr. William Simpson Potter proposes, in his patent, of April, 1835, to
render fabrics water-proof by imbuing them with a solution of isinglass,
alum, and soap, by means of a brush applied to the wrong side of the
cloth, distended upon a table. After it is dry, it must be brushed on
the wrong side, against the grain. Then the brush is to be dipped in
clean water, and passed lightly over the cloth. The gloss caused by the
above application can be taken off by brushing the goods when they are
dry. Cloth so prepared is said to be impervious to water, but not to
air.

I have examined woollen cloth now on sale in a shop in the Strand, which
may be breathed through with the greatest facility, but which retains
water upon its surface, as is evinced by a body of water standing upon a
concave piece of it tied over a show-glass in the window.

Mr. Sievier’s plan of rendering cloth water-proof, for which he obtained
a patent in December, 1835, consists in spreading over it, with a brush,
a solution of India rubber in spirits of turpentine, at one or more
applications, and then applying a similar solution mixed with acetate of
lead, litharge, sulphate of zinc, gum mastic, or other drying material.
He next takes wool, or other textile material, cut into proper lengths,
and spreads it upon the surface of the fabric varnished in this manner,
for the purpose of forming the nap or pile. He then presses the cloth by
means of rollers, or brushes, so as to fix the nap firmly to its
surface.


WATERS, MINERAL--TABLE I. ANALYSES of the principal MINERAL WATERS of
Germany.

  +------------------------+-----------+----------+--------+-------+-------+
  |Grains of Anhydrous     | Carlsbad. |    ms.   |Schlesi-|Marien-|Auscho-|
  |Ingredients in One      |           |          | scher. | bad.  |witz.  |
  |Pound Troy.             |           |          | Ober-  |Kreutz-|Ferdi- |
  |                        |           |          | salz-  |  br.  |nands- |
  |                        |           |          |brunnen.|       |brun-  |
  |                        |           |          |        |       |nen.   |
  +------------------------+-----------+----------+--------+-------+-------+
  |Carbonate of Soda       |  7·2712   |  8·0625  | 6·1133 | 5·3499| 4·5976|
  |Ditto of Lithia         |  0·0150   |  0·0405  | 0·0127 | 0·0858| 0·0507|
  |Ditto of Baryta         |    --     |  0·0022  |   --   |   --  |   --  |
  |Ditto of Strontia       |  0·0055   |  0·0080  | 0·0165 | 0·0028| 0·0040|
  |Ditto of Lime           |  1·7775   |  0·8555  | 1·7497 | 2·9509| 3·0085|
  |Ditto of Magnesia       |  1·0275   |  0·5915  | 1·4107 | 2·0390| 2·2867|
  |Do. (Proto) of Manganese|  0·0048   |  0·0028  |   --   | 0·0288| 0·0692|
  |Ditto (Proto) of Iron   |  0·0208   |  0·0120  | 0·0480 | 0·1319| 0·2995|
  |Sub-Phos. of Lime       |  0·0012   |    --    |   --   |   --  |   --  |
  |Ditto of Alumina        |  0·0019   |  0·0014  | 0·0045 |   --  | 0·0040|
  |Sulphate of Potassa     |    --     |  0·4050  | 0·2220 |   --  |   --  |
  |Ditto of Soda           | 14·9019   |    --    | 2·2095 |28·5868|16·9022|
  |Ditto of Lithia         |    --     |    --    |   --   |   --  |   --  |
  |Ditto of Lime           |    --     |    --    |   --   |   --  |   --  |
  |Ditto of Strontia       |    --     |    --    |   --   |   --  |   --  |
  |Ditto of Magnesia       |    --     |    --    |   --   |   --  |   --  |
  |Nitr. of Magnesia       |    --     |    --    |   --   |   --  |   --  |
  |Chlor. of Potassium     |  - -      |  0·0338  |   --   |   --  |   --  |
  |Ditto of Sodium         |  5·9820   |  5·7255  | 0·8752 |10·1727| 6·7472|
  |Ditto of Magnesium      |  - -      |    --    |   --   |   --  |   --  |
  |Fluoride of Calcium     |  0·0184   |  0·0014  |   --   |   --  |   --  |
  |Alumina                 |  - -      |    --    |   --   | 0·0023|   --  |
  |Silica                  |  0·4329   |  0·3104  | 0·2531 | 0·2908| 0·5023|
  |                        +-----------+----------+--------+-------+-------+
  |Total                   | 31·4606   | 16·0525  |12·9152 |49·6417|34·4719|
  |                        +-----------+----------+--------+-------+-------+
  |Carbonic Acid Gas in 100|           |          |        |       |       |
  |cubic inches            |    58     |   51     |  98    |  105  |  146  |
  |Temperature (F.)        |Sprud. 165°|          |        |       |       |
  |                        |Neub.  138°|Kess. 117°|  58°   |   53° |   46° |
  |                        |Mühl.  128°|Krän.  84°|        |       |       |
  |                        |Ther.  122°|          |        |       |       |
  |Analyzed by             |Berzelius. |Struve.   |Struve. |Berze- |Stein- |
  |                        |           |          |        |lius.  |mann.  |
  +------------------------+-----------+----------+--------+-------+-------+

  +------------------------+------+-------+------+-------+------+-------+
  |Grains of Anhydrous     |Eger. |  Pyr- | Spa. | Fach- |Geil- | Selt- |
  |Ingredients in One      |Fran- | mont. | Pou- |ingen. | nau. | zer.  |
  |Pound Troy.             |zens- |       | hon. |       |      |       |
  |                        |brun- |       |      |       |      |       |
  |                        |nen.  |       |      |       |      |       |
  |                        |      |       |      |       |      |       |
  +------------------------+------+-------+------+-------+------+-------+
  |Carbonate of Soda       |3·8914|   --  |0·5531|12·3328|4·9658| 4·6162|
  |Ditto of Lithia         |0·0282|       |      |       |      |       |
  |Ditto of Baryta         |  --  |   --  |  --  |  --   |  --  | 0·0014|
  |Ditto of Strontia       |0·0023|   --  |  --  |  --   |  --  | 0·0144|
  |Ditto of Lime           |1·3501| 4·7781|0·7387| 1·8667|2·2279| 1·4004|
  |Ditto of Magnesia       |0·5040|   --  |0·8425| 1·2983|1·6282| 1·5000|
  |Do. (Proto) of Manganese|0·0322| 0·0364|0·0389|  --   |  --  |  --   |
  |Ditto (Proto) of Iron   |0·1762| 0·3213|0·2813|  --   |  --  |  --   |
  |Sub-Phos. of Lime       |0·0172|   --  |0·0102| 0·0061|  --  | 0·0007|
  |Ditto of Alumina        |0·0092| 0·0110|0·0064|  --   |  --  | 0·0020|
  |Sulphate of Potassa     | --   | 0·0314|0·0598|  --   |0·2154| 0·2978|
  |Ditto of Soda           |8·3785| 1·6092|0·0289| 0·1267|0·0315|  --   |
  |Ditto of Lithia         | --   | 0·0067|  --  |  --   |  --  |  --   |
  |Ditto of Lime           | --   | 5·0265|  --  |  --   |  --  |  --   |
  |Ditto of Strontia       | --   | 0·0154|  --  |  --   |  --  |  --   |
  |Ditto of Magnesia       | --   | 2·3684|  --  |  --   |  --  |  --   |
  |Nitr. of Magnesia       | --   |   --  |  --  |  --   |  --  |  --   |
  |Chlor. of Potassium     | --   |   --  |  --  |  --   |  --  | 0·2685|
  |Ditto of Sodium         |6·9229|   --  |0·3371| 3·2337|0·4072|12·9690|
  |Ditto of Magnesium      |  --  | 0·8450|  --  |  --   |  --  |  --   |
  |Fluoride of Calcium     |  --  |   --  |  --  |  --   |  --  | 0·0013|
  |Alumina                 |  --  |   --  |  --  |  --   |0·0185|       |
  |Silica                  |0·3548| 0·3727|0·3739| 0·0657|0·2021| 0·2265|
  |                        +------+-------+------+-------+------+-------+
  |Total                   |1·6670|15·4221|3·2691|18·9300|9·6966|21·2982|
  |                        +------+-------+------+-------+------+-------+
  |Carbonic Acid Gas in 100|      |       |      |       |      |       |
  |cubic inches            | 154  |  160  |  136 |  135  |  163 |  126  |
  |Temperature (F.)        |      |       |      |       |      |       |
  |                        |  53° |   56° |  50° |   50° |  51° |   58° |
  |                        |      |       |      |       |      |       |
  |                        |      |       |      |       |      |       |
  |Analyzed by             |Berze-|Struve.|Stru- |Bi-    |Stru- |Struve.|
  |                        |ius   |       |ve.   |schoff.|ve.   |       |
  +------------------------+------+-------+------+-------+------+-------+

  +------------------------+-------+-------+--------+
  |Grains of Anhydrous     | Selt- | Seid- |Püllna. |
  |Ingredients in One      | zer.  |schutz.|        |
  |Pound Troy.             |       |       |        |
  |                        |       |       |        |
  |                        |       |       |        |
  |                        |       |       |        |
  +------------------------+-------+-------+--------+
  |Carbonate of Soda       | 4·6162|       |        |
  |Ditto of Lithia         |       |       |        |
  |Ditto of Baryta         | 0·0014|       |        |
  |Ditto of Strontia       | 0·0144|       |        |
  |Ditto of Lime           | 1·4004| 5·1045|  0·5775|
  |Ditto of Magnesia       | 1·5000| 0·8235|  4·8045|
  |Do. (Proto) of Manganese|  --   | 0·0032|        |
  |Ditto (Proto) of Iron   |  --   | 0·0095|        |
  |Sub-Phos. of Lime       | 0·0007| 0·0117|  0·0026|
  |Ditto of Alumina        | 0·0020| 0·0088|        |
  |Sulphate of Potassa     | 0·2978| 3·6705|  3·6000|
  |Ditto of Soda           |  --   |17·6220| 92·8500|
  |Ditto of Lithia         |  --   |       |        |
  |Ditto of Lime           |  --   | 1·1287|  1·9500|
  |Ditto of Strontia       |  --   | 0·0347|        |
  |Ditto of Magnesia       |  --   |62·3535| 69·8145|
  |Nitr. of Magnesia       |  --   | 5·9302|        |
  |Chlor. of Potassium     | 0·2685|       |        |
  |Ditto of Sodium         |12·9690|       |        |
  |Ditto of Magnesium      |  --   | 1·2225| 14·7495|
  |Fluoride of Calcium     | 0·0013|       |        |
  |Alumina                 |       |       |        |
  |Silica                  | 0·2265| 0·0900|  0·1320|
  |                        +-------+-------+--------+
  |Total                   |21·2982|98·0133|188·4806|
  |                        +-------+-------+--------+
  |Carbonic Acid Gas in 100|       |       |        |
  |cubic inches            |  126  |    20 |   7    |
  |Temperature (F.)        |       |       |        |
  |                        |   58° |   58° |  58°   |
  |                        |       |       |        |
  |                        |       |       |        |
  |Analyzed by             |Struve.|Struve.|Struve. |
  |                        |       |       |        |
  +------------------------+-------+-------+--------+

TABLE II.--The COMPOSITION of other celebrated MINERAL WATERS.

  +------------------------------+------+--------------------------+
  |Names of the Springs.         |Grains|  Cubic Inches of Gases.  |
  |                              |  of  +------+-----+------+------+
  |                              |water.| Oxy- |Car- |Sulph.|Azote.|
  |                              |      | gen. |bonic|hydro-|      |
  |                              |      |      |acid.| gen. |      |
  +------------------------------+------+------+-----+------+------+
  |                              |      |      |     |      |      |
  |  Kilburn (1)--acidulous.     |138240|  --  | 84·0| 36·0 |   -- |
  |                              |      |      |     |      |      |
  |Sulphurous.                   |      |      |     |      |      |
  |  Harrowgate (2)              |103643|  --  |  8·0| 19·0 |  7·0 |
  |  Moffat (2)                  |103643|  --  |  1·0| 10·0 |  4·0 |
  |  Aix-la-Chapelle (3)         |  8940|  --  |  -- | 13·06|   -- |
  |  Enghein (4)                 | 92160|  --  | 18·5|  7·0 |   -- |
  |                              |      |      |     |      |      |
  |Saline.                       |      |      |     |      |      |
  |  Seidlitz                    | 58309|  --  |  8·0|  --  |   -- |
  |  Cheltenham (5)              |103643|  --  | 30·3|  3·0 | 12·0 |
  |  Plombieres (6)              | 14600|  --  |  -- |  --  |   -- |
  |  Dunblane (7) sp. gr. 1·00475|  7291|  --  |  -- |  --  |   -- |
  |  Pitcaithley (7)             |  7291|  --  |  1·0|  --  |   -- |
  |                              |      |      |     |      |      |
  |Chalybeate.                   |      |      |     |      |      |
  |  Tunbridge (3)               |103643|  1·4 | 10·6|  --  |  4·0 |
  |  Brighton (8)                | 58309|  --  | 18·0|  --  |   -- |
  |  Toplitz (9)                 | 22540|  --  |  -- |  --  |   -- |
  |                              |      |      |     |      |      |
  |Calcareous, nearly pure.      |      |      |     |      |      |
  |  Bath (10)                   | 15360|  --  |  2·4|  --  |   -- |
  |  Buxton (11)                 | 58309|  --  |  -- |  --  |  2·0 |
  |  Bristol (12)                | 58309|  --  | 30·3|  --  |   -- |
  |  Matlock                     | 58309|  --  |  -- |  --  |   -- |
  |  Malvern (13)                | 58309|  --  |  -- |  --  |   -- |
  |                              |      |      |     |      |      |
  |  Dead Sea (14) sp. gr. 1·211 |   100|  --  |  -- |  --  |   -- |
  |     Do.   (15) sp. gr. 1·245 |      |  --  |  -- |  --  |   -- |
  |     Do.   (16) sp. gr. 1·2283|      |  --  |  -- |  --  |   -- |
  |  Sea water, Forth (7)        |  7291|  --  |  -- |  --  |   -- |
  +------------------------------+------+------+-----+------+------+

  +------------------------------+--------------------------+
  |Names of the Springs.         |      Carbonates of       |
  |                              +-----+-----+-----+--------+
  |                              |Soda.|Lime.|Mag- |  Iron. |
  |                              |     |     |ne-  |        |
  |                              |     |     |sia. |        |
  +------------------------------+-----+-----+-----+--------+
  |                              | grs.|grs. |grs. |  grs.  |
  |  Kilburn (1)--acidulous.     |  -- | 2·4 | 1·25| 0·3-1/4|
  |                              |     |     |     |        |
  |Sulphurous.                   |     |     |     |        |
  |  Harrowgate (2)              |  -- |18·5 | 5·5 |   --   |
  |  Moffat (2)                  |  -- | --  |  -- |   --   |
  |  Aix-la-Chapelle (3)         |  -- |15·25| 5·89|   --   |
  |  Enghein (4)                 |  -- |21·4 | 1·35|   --   |
  |                              |     |     |     |        |
  |Saline.                       |     |     |     |        |
  |  Seidlitz                    |  -- | 6·7 |21·0 |   --   |
  |  Cheltenham (5)              |  -- |  -- |12·5 |  5·0   |
  |  Plombieres (6)              | 36·0| 0·4 |  -- |   --   |
  |  Dunblane (7) sp. gr. 1·00475|  -- | 0·5 |  -- |  0·17  |
  |  Pitcaithley (7)             |  -- | 0·5 |  -- |   --   |
  |                              |     |     |     |        |
  |Chalybeate.                   |     |     |     |        |
  |  Tunbridge (3)               |  -- |  -- |  -- |  1·0   |
  |  Brighton (8)                |  -- |  -- |  -- |   --   |
  |  Toplitz (9)                 | 13·5|16·5 |  -- | 32·5   |
  |                              |     |     |     |        |
  |Calcareous, nearly pure.      |     |     |     |        |
  |  Bath (10)                   |  -- | 1·6 |  -- |  0·004 |
  |  Buxton (11)                 |  -- |10·5 |  -- |   --   |
  |  Bristol (12)                |  -- |13·5 |  -- |   --   |
  |  Matlock                     |  -- |  -- |  -- |   --   |
  |  Malvern (13)                | 5·33| 1·6 | 0·92|  0·625 |
  |                              |     |     |     |        |
  |  Dead Sea (14) sp. gr. 1·211 |  -- |  -- |  -- |   --   |
  |     Do.   (15) sp. gr. 1·245 |  -- |  -- |  -- |   --   |
  |     Do.   (16) sp. gr. 1·2283|  -- |  -- |  -- |   --   |
  |  Sea water, Forth (7)        |  -- |  -- |  -- |   --   |
  +------------------------------+-----+-----+-----+--------+

  +------------------------------+--------------------------+
  |Names of the Springs.         |       Sulphates of       |
  |                              +------+------+------+-----+
  |                              |Soda. |Lime. | Mag- |Iron.|
  |                              |      |      | ne-  |     |
  |                              |      |      | sia. |     |
  +------------------------------+------+------+------+-----+
  |                              | grs. | grs. | grs. | grs.|
  |  Kilburn (1)--acidulous.     |18·2  |13·0  |91·0  |  -- |
  |                              |      |      |      |     |
  |Sulphurous.                   |      |      |      |     |
  |  Harrowgate (2)              |  --  |  --  | 0·5  |  -- |
  |  Moffat (2)                  |  --  |  --  |  --  |  -- |
  |  Aix-la-Chapelle (3)         |  --  |  --  |  --  |  -- |
  |  Enghein (4)                 |  --  |33·3  | 5·8  |  -- |
  |                              |      |      |      |     |
  |Saline.                       |      |      |      |     |
  |  Seidlitz                    |  --  |41·1  |14·44 |  -- |
  |  Cheltenham (5)              |48·0  |40·0  |  --  |  -- |
  |  Plombieres (6)              | 1·0  |  --  |  --  |  -- |
  |  Dunblane (7) sp. gr. 1·00475| 3·7  |  --  |  --  |  -- |
  |  Pitcaithley (7)             | 0·9  |  --  |  --  |  -- |
  |                              |      |      |      |     |
  |Chalybeate.                   |      |      |      |     |
  |  Tunbridge (3)               |  --  | 1·25 |  --  |  -- |
  |  Brighton (8)                |  --  |32·7  |  --  |11·2 |
  |  Toplitz (9)                 |  --  |  --  |  --  |  -- |
  |                              |      |      |      |     |
  |Calcareous, nearly pure.      |      |      |      |     |
  |  Bath (10)                   | 3·0  |18·0  |  --  |  -- |
  |  Buxton (11)                 |  --  | 2·5  |  --  |  -- |
  |  Bristol (12)                |11·2  |11·7  |  --  |  -- |
  |  Matlock                     |  --  |trace |  --  |  -- |
  |  Malvern (13)                | 2·896|  --  |  --  |  -- |
  |                              |      |      |      |     |
  |  Dead Sea (14) sp. gr. 1·211 |  --  |  ·054|  --  |  -- |
  |     Do.   (15) sp. gr. 1·245 |  --  |  --  |  --  |  -- |
  |     Do.   (16) sp. gr. 1·2283|  --  |  --  |  --  |  -- |
  |  Sea water, Forth (7)        |25·6  |  --  |  --  |  -- |
  +------------------------------+------+------+------+-----+

  +------------------------------+--------------------------+
  |Names of the Springs.         |       Muriates of        |
  |                              +-------+-----+------+-----+
  |                              | Soda. |Lime.| Mag- |Pot- |
  |                              |       |     | ne-  |ash. |
  |                              |       |     | sia. |     |
  +------------------------------+-------+-----+------+-----+
  |                              |  grs. | grs.|  grs.| grs.|
  |  Kilburn (1)--acidulous.     |  6·0  | 0·6 |  2·8 |  -- |
  |                              |       |     |      |     |
  |Sulphurous.                   |       |     |      |     |
  |  Harrowgate (2)              |615·5  | 3·0 |  9·1 |  -- |
  |  Moffat (2)                  |  3·6  |  -- |   -- |  -- |
  |  Aix-la-Chapelle (3)         |  6·21 |  -- |   -- |  -- |
  |  Enghein (4)                 |  2·4  |  -- |  8·0 |  -- |
  |                              |       |     |      |     |
  |Saline.                       |       |     |      |     |
  |  Seidlitz                    |   --  |  -- | 36·5 |  -- |
  |  Cheltenham (5)              |  5·0  |  -- | 12·5 |  -- |
  |  Plombieres (6)              |  2·0  |  -- |   -- |  -- |
  |  Dunblane (7) sp. gr. 1·00475| 21·0  |20·8 |   -- |  -- |
  |  Pitcaithley (7)             | 12·7  |20·2 |   -- |  -- |
  |                              |       |     |      |     |
  |Chalybeate.                   |       |     |      |     |
  |  Tunbridge (3)               |  0·5  |  -- |  2·25|  -- |
  |  Brighton (8)                | 12·2  |  -- |  6·0 |  -- |
  |  Toplitz (9)                 | 61·3  |28·5 |   -- |  -- |
  |                              |       |     |      |     |
  |Calcareous, nearly pure.      |       |     |      |     |
  |  Bath (10)                   |  6·6  |  -- |   -- |  -- |
  |  Buxton (11)                 |  1·5  |  -- |   -- |  -- |
  |  Bristol (12)                |  4·0  |  -- |  7·25|  -- |
  |  Matlock                     |   --  |  -- |   -- |  -- |
  |  Malvern (13)                |  1·55 |  -- |   -- |  -- |
  |                              |       |     |      |     |
  |  Dead Sea (14) sp. gr. 1·211 | 10·676| 3·8 | 10·1 |     |
  |     Do.   (15) sp. gr. 1·245 |  7·8  |10·6 | 24·2 |     |
  |     Do.   (16) sp. gr. 1·2283|  6·95 | 4·0 | 15·31|     |
  |  Sea water, Forth (7)        |159·3  | 5·7 | 35·5 |trace|
  |                              |       |     |      |[70] |
  +------------------------------+-------+-----+------+-----+

  +------------------------------+----+----+----+-----+
  |Names of the Springs.         |Sil-|Alu-|Res-|Tem- |
  |                              |ica.|mi- |ins.|pera-|
  |                              |    |na. |    |ture.|
  |                              |    |    |    |     |
  |                              |    |    |    |     |
  +------------------------------+----+----+----+-----+
  |                              |grs.|grs.|grs.|     |
  |  Kilburn (1)--acidulous.     | -- | -- | 6·0| cold|
  |                              |    |    |    |     |
  |Sulphurous.                   |    |    |    |     |
  |  Harrowgate (2)              | -- | -- | -- | cold|
  |  Moffat (2)                  | -- | -- | -- | cold|
  |  Aix-la-Chapelle (3)         | -- | -- | -- | 143°|
  |  Enghein (4)                 | -- | -- | -- | cold|
  |                              |    |    |    |     |
  |Saline.                       |    |    |    |     |
  |  Seidlitz                    | -- | -- | -- | cold|
  |  Cheltenham (5)              | -- | -- | -- | cold|
  |  Plombieres (6)              | -- | -- | -- | cold|
  |  Dunblane (7) sp. gr. 1·00475| -- | -- | -- | cold|
  |  Pitcaithley (7)             | -- | -- | -- | cold|
  |                              |    |    |    |     |
  |Chalybeate.                   |    |    |    |     |
  |  Tunbridge (3)               | -- | -- | -- | cold|
  |  Brighton (8)                |1·12| -- | -- | cold|
  |  Toplitz (9)                 | -- |15·1| -- | cold|
  |                              |    |    |    |     |
  |Calcareous, nearly pure.      |    |    |    |     |
  |  Bath (10)                   | 0·4| -- | -- | 114°|
  |  Buxton (11)                 | -- | -- | -- |  82°|
  |  Bristol (12)                | -- | -- | -- |  74°|
  |  Matlock                     | -- | -- | -- |  66°|
  |  Malvern (13)                | -- | -- | -- | cold|
  |                              |    |    |    |     |
  |  Dead Sea (14) sp. gr. 1·211 |    |    |    |     |
  |     Do.   (15) sp. gr. 1·245 |    |    |    |     |
  |     Do.   (16) sp. gr. 1·2283|    |    |    |     |
  |  Sea water, Forth (7)        |    |    |    |     |
  +------------------------------+----+----+----+-----+

  (1) Schmesser.
  (2) Garnet.
  (3) Babington.
  (5) Fothergill.
  (6) Vauquelin.
  (7) Dr. Murray.
  (8) Marcet.
  (9) John.
  (10) Phillips.
  (11) Pearson.
  (12) Carrick.
  (13) Dr. Philip.
  (14) Dr. Marcet.
  (15) Klaproth.
  (16) M. Gay Lussac.

  [70] Dr. Wollaston.

Mineral waters may, in most cases, be artificially prepared, by the
skilful application of the knowledge derived from analysis, with such
precision as to imitate very closely the native springs. When the
various earthy or metallic constituents, are held in solution by
carbonic acid, or sulphuretted, they should be placed along with their
due proportions of water, in the receiver of the aerating machine (see
SODA WATER), and then the proper quantity of gas should be injected into
the water. Sufficient agitation will be given by the action of the
forcing-pump to promote their solution.


WAX (_Cire_, Fr.; _Wachs_, Germ.); is the substance which forms the
cells of bees. It was long supposed to be derived from the pollen of
plants, swallowed by these insects, and merely voided under this new
form; but it has been proved by the experiments, first of Mr. Hunter,
and more especially of M. Huber, to be the peculiar secretion of a
certain organ, which forms a part of the small sacs, situated on the
sides of the median line of the abdomen of the bee. On raising the lower
segments of the abdomen, these sacs may be observed, as also scales or
spangles of wax, arranged in pairs upon each segment. There are none,
however, under the rings of the males and the queen. Each individual has
only eight wax sacs, or pouches; for the first and the last ring are not
provided with them. M. Huber satisfied himself by precise experiments
that bees, though fed with honey, or sugar alone, produced nevertheless
a very considerable quantity of wax; thus proving that they were not
mere collectors of this substance from the vegetable kingdom. The pollen
of plants serves for the nourishment of the larvæ.

But wax exists also as a vegetable product, and may, in this point of
view, be regarded as a concrete fixed oil. It forms a part of the green
fecula of many plants, particularly of the cabbage; it may be extracted
from the pollen of most flowers; as also from the skins of plums, and
many stone fruits. It constitutes a varnish upon the upper surface of
the leaves of many trees, and it has been observed in the juice of the
_cow-tree_. The berries of the _Myrica angustifolia_, _latifolia_, as
well as the _cerifera_, afford abundance of wax.

Bees’ wax, as obtained by washing and melting the comb, is yellow. It
has a peculiar smell, resembling honey, and derived from it, for the
cells in which no honey has been deposited, yield a scentless white wax.
Wax is freed from its impurities, and bleached, by melting it with hot
water or steam, in a tinned copper or wooden vessel, letting it settle,
running off the clear supernatant oily-looking liquid into an oblong
trough with a line of holes in its bottom, so as to distribute it upon
horizontal wooden cylinders, made to revolve half immersed in cold
water, and then exposing the thin ribbons or films thus obtained to the
blanching action of air, light, and moisture. For this purpose, the
ribbons are laid upon long webs of canvas stretched horizontally between
standards, two feet above the surface of a sheltered field, having a
free exposure to the sunbeams. Here they are frequently turned over,
then covered by nets to prevent their being blown away by winds, and
watered from time to time, like linen upon the grass field in the old
method of bleaching. Whenever the colour of the wax seems stationary, it
is collected, remelted, and thrown again into ribbons upon the wet
cylinder, in order to expose new surfaces to the blanching operation. By
several repetitions of these processes, if the weather proves
favourable, the wax eventually loses its yellow tint entirely, and
becomes fit for forming white candles. If it be finished under rain, it
will become gray on keeping, and also lose in weight.

In France, where the purification of wax is a considerable object of
manufacture, about four ounces of cream of tartar, or alum, are added to
the water in the first melting-copper, and the solution is incorporated
with the wax by diligent manipulation. The whole is left at rest for
some time, and then the supernatant wax is run off into a settling
cistern, whence it is discharged by a stopcock or tap, over the wooden
cylinder revolving at the surface of a large water-cistern, kept cool by
passing a stream continually through it.

The bleached wax is finally melted, strained through silk sieves, and
then run into circular cavities in a moistened table, to be cast or
moulded into thin disc pieces, weighing from two to three ounces each,
and three or four inches in diameter.

Neither chlorine, nor even the chlorides of lime and alkalis, can be
employed with any advantage to bleach wax, because they render it
brittle, and impair its burning quality.

Wax purified, as above, is white and translucent in thin segments; it
has neither taste nor smell; it has a specific gravity of from 0·960 to
0·966; it does not liquefy till it be heated to 154-1/2° F.; but it
softens at 86°, becoming so plastic, that it may be moulded by the hand
into any form. At 32° it is hard and brittle.

It is not a simple substance, but consists of two species of wax, which
may be easily separated by boiling alcohol. The resulting solution
deposits, on cooling, the waxy body called _cerine_. The undissolved
wax, being once and again treated with boiling alcohol, finally affords
from 70 to 90 per cent. of its weight of cerine. The insoluble residuum
is the _myricine_ of Dr. John, so called because it exists in a much
larger proportion in the wax of the _Myrica cerifera_. It is greatly
denser than wax, being of the same specific gravity as water; and may be
distilled without decomposition, which cerine undergoes. See these two
articles.

Wax is adulterated sometimes with starch; a fraud easily detected by oil
of turpentine, which dissolves the former, and leaves the latter
substance; and more frequently with mutton suet. This fraud may be
discovered by dry distillation; for wax does not thereby afford, like
tallow, sebacic acid (benzoic), which is known by its occasioning a
precipitate in a solution of acetate of lead. It is said that two per
cent. of a tallow sophistication may be discovered in this way.

Bees’ wax imported for home consumption:--in 1835, unbleached, 4,449
cwts.; bleached, 243 cwts.;--in 1836, unbleached, 4,673 cwts.; bleached,
121 cwts. Duty, when from British possessions, 10_s._; from foreign,
30_s._


WAX, MINERAL, or _Ozocerite_, is a solid, of a brown colour, of various
shades, translucent, and fusible like bees’ wax; slightly bituminous to
the smell, of a foliated texture, a conchoidal fracture, but wanting
tenacity, so that it can be pulverized in a mortar. Its specific gravity
varies from 0·900 to 0·953. Candles have been made of it in Moldavia,
which give a tolerable light. It occurs at the foot of the Carpathians
near Slanik, beneath a bed of bituminous slate-clay, in masses of from
80 to 100 pounds weight. Layers of brown amber are found in the
neighbourhood. It is associated with variegated sandstone, rock salt,
and beds of coal (lignite?). It is analogous to _hatchetine_. Something
similar has been discovered in a _trouble_ at Urpeth colliery, near
Newcastle, 60 fathoms beneath the surface. _Ozocerite_ consists of
different hydro-carburetted compounds associated together; the whole
being composed, ultimately, of--hydrogen 14, carbon 86, very nearly.

[Illustration: 1159]


WEAVING (_Tissage_, Fr.; _Weberei_, Germ.); is performed by the
implement called _loom_ in English, _métier à tisser_ in French, and
_weberstuhl_ in German. The process of warping must always precede
weaving. Its object is to arrange all the longitudinal threads, which
are to form the chain of the web, alongside of each other in one
parallel plane. Such a number of bobbins, filled with yarn, must
therefore be taken as will furnish the quantity required for the length
of the intended piece of cloth. One-sixth of that number of bobbins is
usually mounted at once in the warp mill, being set loosely in a
horizontal direction upon wire skewers, or spindles, in a square frame,
so that they may revolve, and give off the yarn freely. The warper sits
at A, _fig._ 1159., and causes the reel B to revolve, by turning round
with his hand the wheel C, with the endless rope or band D. The bobbins
filled with yarn are placed in the frame E. There is a sliding piece at
F, called the _heck_ box, which rises and falls by the coiling and
uncoiling of the cord G, round the central shaft of the reef H. By this
simple contrivance, the band of warp-yarns is wound spirally, from top
to bottom, upon the reel. I, I, I, are wooden pins which separate the
different bands. Most warping mills are of a prismatic form; having
twelve, eighteen, or more sides. The reel is commonly about six feet in
diameter, and seven feet in height, so as to serve for measuring exactly
upon its periphery the total length of the warp. All the threads from
the frame E, pass through the heck F, which consists of a series of
finely-polished hard-tempered steel pins, with a small hole at the upper
part of each, to receive and guide one thread. The heck is divided into
two parts, either of which may be lifted by a small handle below, while
their eyes are placed alternately. Hence, when one of them is raised a
little, a vacuity is formed between the two bands of the warp; but when
the other is raised, the vacuity is reversed. In this way, the lease is
produced at each end of the warp, and it is preserved by appropriate
wooden pegs. The lease being carefully tied up, affords a guide to the
weaver for inserting his lease-rods. The warping mill is turned
alternately from right to left, and from left to right, till a
sufficient number of yarns are coiled round it to form the breadth that
is wanted; the warper’s principal care being to tie immediately every
thread as it breaks, otherwise deficiencies would be occasioned in the
chain, injurious to the appearance of the web, or productive of much
annoyance to the weaver.

[Illustration: 1160]

The simplest and probably the most antient of looms, now to be seen in
action, is that of the Hindu tanty, shown in _fig._ 1160. It consists of
two bamboo rollers; one for the warp, and another for the woven cloth;
with a pair of heddles, for parting the warp, to permit the weft to be
drawn across between its upper and under threads. The shuttle is a
slender rod, like a large netting needle, rather longer than the web is
broad, and is made use of as a batten or lay, to strike home or condense
each successive thread of weft, against the closed fabric. The Hindu
carries this simple implement, with his water pitcher, rice pot, and
hooka, to the foot of any tree which can afford him a comfortable shade;
he there digs a large hole, to receive his legs, along with the treddles
or lower part of the harness; he next extends his warp, by fastening his
two bamboo rollers, at a proper distance from each other, with pins,
into the sward; he attaches the heddles to a convenient branch of the
tree overhead; inserts his great toes into two loops under the geer, to
serve him for treddles; lastly, he sheds the warp, draws through the
weft, and beats it close up to the web with his rod-shuttle or batten.

[Illustration: 1161]

The European loom is represented in its plainest state, as it has
existed for several centuries, in _fig._ 1161. A is the warp-beam, round
which the chain, has been wound; B represents the flat rods, usually
three in number, which pass across between its threads, to preserve the
lease, or the plane of decussation for the weft; C shows the heddles or
healds, consisting of twines looped in the middle, through which loops,
the warp yarns are drawn, one half through the front heddle, and the
other through the back one; by moving which, the decussation is readily
effected. The yarns then pass through the dents of the REED under D,
which is set in a movable swing-frame E, called the lathe, lay, and also
batten, because it _beats_ home the weft to the web. The lay is freely
suspended to a cross-bar F, attached by rulers, called the _swords_, to
the top of the lateral standards of the loom, so as to oscillate upon
it. The weaver, sitting on the bench G, presses down one of the treddles
at H, with one of his feet, whereby he raises the corresponding heddle,
but sinks the alternate one; thus sheds the warp, by lifting and
depressing each alternate thread, through a little space, and opens a
pathway or race-course for the shuttle to traverse the middle of the
warp, upon its two friction rollers M, M. For this purpose, he lays hold
of the picking-peg in his right hand, and, with a smart jerk of his
wrist, drives the fly-shuttle swiftly from one side of the loom to the
other, between the shed warp yarns. The shoot of weft being thereby left
behind from the shuttle pirn or cop, the weaver brings home, by pulling,
the lay with its reed towards him by his left hand, with such force as
the closeness of the texture requires. The web, as thus woven, is wound
up by turning round the cloth beam I, furnished with a ratchet-wheel,
which takes into a holding tooth. The plan of throwing the shuttle by
the picking-peg and cord, is a great improvement upon the old way of
throwing it by hand. It was contrived exactly a century ago, by John
Kay, of Bury in Lancashire, but then resident in Colchester, and was
called the fly-shuttle, from its speed, as it enabled the weaver to make
double the quantity of narrow cloth, and much more broad cloth, in the
same time.

The cloth is kept distended, during the operation of weaving, by means
of two pieces of hard wood, called a templet, furnished with sharp iron
points in their ends, which take hold of the opposite selvages or lists
of the web. The warp and web are kept longitudinally stretched by a
weighted cord, which passes round the warp-beam, and which tends
continually to draw back the cloth from its beam, where it is held fast
by the ratchet tooth. See FUSTIAN, JACQUARD LOOM, REED, and TEXTILE
FABRICS.

[Illustration: 1162 1163 1164]

The greater part of plain weaving, and much even of the figured, is now
performed by the power loom, called _métier mécanique à tisser_, in
French. _Fig._ 1162. represents the cast-iron power loom of Sharp and
Roberts. A, A´, are the two side uprights, or standards, on the front of
the loom. D, is the great arch of cast iron, which binds the two sides
together. E, is the front cross-beam, terminating in the forks _e_, _e_;
whose ends are bolted to the opposite standards A, A´, so as to bind
the framework most firmly together. G´, is the breast beam, of wood,
nearly square; its upper surface is sloped a little towards the front,
and its edge rounded off, for the web to slide smoothly over it, in its
progress to the cloth beam. The beam is supported at its end upon
brackets, and is secured by the bolts _g´_, _g´_. H, is the cloth beam,
a wooden cylinder, mounted with iron gudgeons at its ends, that on the
right hand being prolonged to carry the toothed winding wheel H´. _k´_
is a pinion in geer with H´. H´´, is a ratchet wheel, mounted upon the
same shaft _h´´´_, as the pinion _h´_. _h´_, is the click of the ratchet
wheel H´´. _k´´´_, is a long bolt fixed to the frame, serving as a shaft
to the ratchet wheel H´´, and the pinion _h´_. I, is the front
heddle-leaf, and I´, the back one. J, J, J´, J´, jacks or pulleys and
straps, for raising and depressing the leaves of the heddles. J´´, is
the iron shaft which carries the jacks or system of pulleys J, J, J´,
J´. K, a strong wooden ruler, connecting the front heddle with its
treddle. L, L´, the front and rear marches or treddle-pieces, for
depressing the heddle leaves alternately, by the intervention of the
rods _k_, (and _k´_, hid behind _k_). M, M, are the two swords (swing
bars) of the lay or batten. N, is the upper cross-bar of the lay, made
of wood, and supported upon the squares of the levers _n_, _n´_, to
which it is firmly bolted. N´, is the lay-cap, which is placed higher or
lower, according to the breadth of the reed; it is the part of the lay
which the hand-loom weaver seizes with his hand, in order to swing it
towards him. _n´_, is the reed contained between the bar N, and the
lay-cap N´. O, O, are two rods of iron, perfectly round and straight,
mounted near the ends of the batten-bar N, which serve as guides to the
drivers or peckers _o_, _o_, which impel the shuttle. These are made of
buffalo hide, and should slide freely on their guide-rods. O´, O´, are
the fronts of the shuttle-boxes; they have a slight inclination
backwards. P, is the back of them. See _figs._ 1163. and 1164. O´´, O´´
are iron plates, forming the bottoms of the shuttle-boxes. _p_, small
pegs or pins, planted in the posterior faces P (_fig._ 1164.) of the
boxes, round which the levers P´ turn. These levers are sunk in the
substance of the faces P, turn round pegs _p_, being pressed from
without inwards, by the springs _p´_. P´´, _fig._ 1162. (to the right of
K,) is the whip or lever, (and Q´´, its centre of motion, corresponding
to the right arm and elbow of the weaver,) which serves to throw the
shuttle, by means of the pecking-cord _p´´_, attached at its other end
to the drivers _o_, _o_.

On the axis of Q´´, a kind of eccentric or heart wheel is mounted, to
whose concave part, the middle of the double band or strap _r_, being
attached, receives impulsion; its two ends are attached to the heads of
the bolts _r´_, which carry the stirrups _r´´_, that may be adjusted at
any suitable height, by set screws.

S (see the left-hand side of _fig._ 1162.), is the moving shaft, of
wrought iron, resting on the two ends of the frame, S´ (see the
right-hand side), is a toothed wheel, mounted exteriorly to the frame,
upon the end of the shaft S. S´´ (near S´), are two equal elbows, in the
same direction, and in the same plane, as the shaft S, opposite to the
swords M, M, of the lay.

Z, is the loose, and Z´, the fast pulley, or riggers, which receive
motion from the steam-shaft of the factory, Z´´, a small fly-wheel, to
regulate the movements of the main shaft of the loom.

T, is the shaft of the eccentric tappets, cams, or wipers, which press
the treddle levers alternately up and down; on its right end is mounted
T´, a toothed wheel in geer with the wheel S´, of one half its diameter.
T´´, is a cleft clamping collar, which serves to support the shaft T.

U, is a lever, which turns round the bolt _u_, as well as the click
_h´´_. U´, is the click of traction, for turning round the cloth beam,
jointed to the upper extremity of the lever U; its tooth _u´_, catches
in the teeth of the ratchet wheel H´´. _u´´_, is a long slender rod,
fixed to one of the swords of the lay M, serving to push the lower end
of the lever U, when the lay retires towards the heddle leaves.

X, is a wrought-iron shaft, extending from the one shuttle-box to the
other, supported at its ends by the bearings _x_, _x_.

Y, is a bearing, affixed exteriorly to the frame, against which the
spring bar Z, rests, near its top, but is fixed to the frame at its
bottom. The spring falls into a notch in the bar Y, and is thereby held
at a distance from the upright A, as long as the band is upon the loose
pulley _z´_; but when the spring bar is disengaged, it falls towards A,
and carries the band upon the fast pulley _z_, so as to put the loom in
geer with the steam-shaft of the factory.

Weaving, by this powerful machine, consists of four operations: 1. to
shed the warp by means of the heddle leaves, actuated by the tappet
wheels upon the axis Q´, the rods _k_, _k´_, the cross-bar E, and the
eyes of the heddle leaves I, I´; 2. to throw the shuttle (see _fig._
1161.), by means of the whip lever P´´, the driver cord _p_, and the
pecker _o_; 3. to drive home the weft by the batten N, N´; 4. to unwind
the chain from the warp beam, and to draw it progressively forwards, and
wind the finished web upon the cloth beam H, by the click and toothed
wheel mechanism at the right-hand side of the frame. For more minute
details, the reader may consult _The Cotton Manufacture of Great
Britain_, vol. ii. p. 291.


WEFT (_Trame_, Fr.; _Eintrag_, Germ.); is the name of the yarns or
threads which run from selvage to selvage in a web.


WELD (_Vouëde_, Fr.; _Wau_, _Gelbkraut_, Germ.); is an annual herbaceous
plant, which grows all over Europe, called by botanists _Reseda
luteola_. The stems and the leaves dye yellow; and among the dyes of
organic nature, they rank next to the Persian berry for the beauty and
fastness of colour. The whole plant is cropped when in seed, at which
period its dyeing power is greatest; and after being simply dried, is
brought into the market.

Chevreul has discovered a yellow colouring principle in weld, which he
has called _luteoline_. It may be sublimed, and thus obtained in long
needle-form, transparent yellow crystals. Luteoline is but sparingly
soluble in water; but it nevertheless dyes alumed silk and wool of a
fine jonquil colour. It is soluble in alcohol and ether; it combines
with acids, and especially with bases.

When weld is to be employed in the dye-bath, it should be boiled for
three quarters of an hour; after which the exhausted plant is taken out,
because it occupies too much room. The decoction is rapidly decomposed
in the air, and ought therefore to be made only when it is wanted. It
produces with,

  Solution of isinglass            a slight turbidity.
  Litmus paper                     a faint reddening.
  Potash lye                       a golden yellow tint.
  Solution of alum                 a faint yellow.
  Protoxide salts of tin           a rich yellow        }
  Acetate of lead                       ditto           } precipitation.
  Salts of copper                  a dirty yellow-brown }
  Sulphate of red oxide of iron    a brown, passing into olive.

A lack is made from decoction of weld with alum, precipitated by
carbonate of soda or potassa. See YELLOW DYE.


WELDING (_Souder_, Fr.; _Schweissen_, Germ.); is the property which
pieces of wrought iron possess, when heated to whiteness, of uniting
intimately and permanently under the hammer, into one body, without any
appearance of junction. The welding temperature is usually estimated at
from 60° to 90° of Wedgewood. When a skilful blacksmith is about to
perform the welding operation, he watches minutely the effect of the
heat in his forge-fire upon the two iron bars; and if he perceives them
beginning to burn, he pulls them out, rolls them in sand, which forms a
glassy silicate of iron upon the surface, so as to prevent further
oxidizement; and then laying the one properly upon the other, he
incorporates them by his right-hand hammer, being assisted by another
workman, who strikes the metal at the same time with a heavy
forge-hammer.

_Platinum_ is not susceptible of being welded, as many chemical authors
have erroneously asserted.

Mr. T. H. Russell, of Handsworth, near Birmingham, obtained a patent, in
May, 1836, for manufacturing welded iron tubes, by drawing or passing
the skelp, or fillet of sheet iron, five feet long, between dies or
holes, formed by a pair of grooved rollers, placed with their sides
contiguous; for which process, he does not previously turn up the skelp
from end to end, but he does this so as to bring the edges together at
the time when the welding is performed. He draws the skelp through two
or more pairs of the above pincers or dies, each of less dimension than
the preceding. In making tubes of an inch of internal diameter, a skelp
four inches and a half broad is employed. The twin rollers revolve on
vertical axes, which may be made to approach each other to give
pressure; and they are kept cool by a stream of water, while the skelp,
ignited to the welding heat, is passed between them. They are affixed at
about a foot in front of the mouth of the furnace, on a draw-bench;
there being a suitable stop within a few inches of the rollers, against
which the workman may place a pair of pincers, having a bell-mouthed
hole or die, for welding and shaping the tube. In the first passage
between the rollers, a circular revolving plate of iron is let down
vertically between them, to prevent the edges of the skelp from
overlapping, or even meeting. The welding is performed at the last
passage.


WELLS, ARTESIAN. See also ARTESIAN WELLS. The following account of a
successful operation of this kind, lately performed at Mortlake, in
Surrey, deserves to be recorded. The spot at which this undertaking was
begun, is within 100 feet of the Thames. In the first instance, an
auger, seven inches in diameter, was used in penetrating 20 feet of
superficial detritus, and 200 feet of London clay. An iron tube, 8
inches in diameter, was then driven into the opening, to dam out the
land-springs and the percolation from the river. A 4-inch auger was next
introduced through the iron tube, and the boring was continued until,
the London clay having been perforated to the depth of 240 feet, the
sands of the plastic clay were reached, and water of the softest and
purest nature was obtained; but the supply was not sufficient, and it
did not reach the surface. The work was proceeded with accordingly; and
after 55 feet of alternating beds of sand and clay had been penetrated,
the chalk was touched upon. A second tube, 4-1/2 inches in diameter, was
then driven into the chalk, to stop out the water of the plastic sands;
and through this tube an auger, 3-1/2 inches in diameter, was
introduced, and worked down through 35 feet of hard chalk, abounding
with flints. To this succeeded a bed of soft chalk, into which the
instrument suddenly penetrated to the depth of 15 feet. On the auger
being withdrawn, water gradually rose to the surface, and overflowed.
The expense of the work did not exceed 300_l._ The general summary of
the strata penetrated is as follows:--Gravel, 20 feet; London clay, 250;
plastic sands and clays, 55; hard chalk with flints, 35; soft chalk, 15;
= 375 feet.


WHALEBONE (_Baleine_, Fr.; _Fischbeine_, Germ.); is the name of the
horny laminæ, consisting of fibres laid lengthwise, found in the mouth
of the whale, which, by the fringes upon their edges, enable the animal
to allow the water to flow out, as through rows of teeth (which it
wants), from between its capacious jaws, but to catch and detain the
minute creatures upon which it feeds. The fibres of whalebone have
little lateral cohesion, as they are not transversely decussated, and
may, therefore, be readily detached in the form of long filaments or
bristles. The _blades_, or scythe-shaped plates, are externally compact,
smooth, and susceptible of a good polish. They are connected, in a
parallel series, by what is called the _gum_ of the animal, and are
arranged along each side of its mouth, to the number of about 300. The
length of the longest _blade_, which is usually found near the middle of
the series, is the gauge adopted by the fishermen to designate the size
of the fish. The greatest length hitherto known has been 15 feet, but it
rarely exceeds 12 or 13. The breadth, at the root end, is from 10 to 12
inches; and the average thickness, from four to five tenths of an inch.
The series, viewed altogether in the mouth of the whale, resemble, in
general form, the roof of a house. They are cleansed and softened before
cutting, by boiling for two hours in a long copper.

[Illustration: 1165]

Whalebone, as brought from Greenland, is commonly divided into portable
junks or pieces, comprising ten or twelve blades in each; but it is
occasionally subdivided into separate blades, the gum and the hairy
fringes having been removed by the sailors during the voyage. The price
of whalebone fluctuates from 50_l._ to 150_l._ per ton. The blade is cut
into parallel prismatic slips, as follows:--It is clamped horizontally,
with its edge up and down, in the large wooden vice of a carpenter’s
bench, and is then planed by the following tool: _fig._ 1165. A, B, are
its two handles; C, D, is an iron plate, with a guide-notch E; F, is a
semicircular knife, screwed firmly at each end to the ends of the iron
plate C, D, having its cutting edge adjusted in a plane, so much lower
than the bottom of the notch E, as the thickness of the whalebone slip
is intended to be; for different thicknesses, the knife may be set by
the screws at different levels, but always in a plane parallel to the
lower guide surface of the plate C, D. The workman, taking hold of the
handles A, B, applies the notch of the tool at the end of the whalebone
blade furthest from him, and with his two hands pulls it steadily along,
so as to shave off a slice in the direction of the fibres; being careful
to cut none of them across. These prismatic slips are then dried, and
planed level upon their other two surfaces. The fibrous matter detached
in this operation, is used, instead of hair, for stuffing mattresses.

From its flexibility, strength, elasticity, and lightness, whalebone is
employed for many purposes: for ribs to umbrellas or parasols; for
stiffening stays; for the framework of hats, &c. When heated by steam,
or a sand-bath, it softens, and may be bent or moulded, like horn, into
various shapes, which it retains, if cooled under compression. In this
way, snuff-boxes, and knobs of walking-sticks, may be made from the
thicker parts of the blade. The surface is polished at first with ground
pumice-stone, felt, and water; and finished with dry quicklime,
spontaneously slaked, and sifted.


WHEAT. (_Triticum vulgare_, Linn.; _Froment_, Fr.; _Waizen_, Germ.) See
BREAD, GLUTEN, and STARCH.


WHEEL CARRIAGES. Though this manufacture belongs most properly to a
treatise upon mechanical engineering, I shall endeavour to describe the
parts of a carriage, so as to enable gentlemen to judge of its make and
relative merits. The external form may vary with every freak of fashion;
but the general structure of a vehicle, as to lightness, elegance, and
strength, may be judged of from the following figure and description.

[Illustration: 1166]

_Fig._ 1166. shows the body of a chariot, hung upon an iron carriage,
with iron wheels, axletrees, and boxes; the latter, by a simple
contrivance, is close at the out-head, by which means the oil cannot
escape; and the fastening of the wheel being at the in-head, as will be
explained afterwards, gives great security, and prevents the possibility
of the wheel being taken off by any other carriage running against it.

[Illustration: 1167 1168]

_Fig._ 1167. shows the arm of an axletree, turned perfectly true, with
two collars in the solid, as seen at G and H. The parts from G to B are
made cylindrical. At K is a screw nail, the purpose of which will be
explained in _fig._ 1171.

_Fig._ 1168. is the longitudinal section of a metal nave, which also
forms the bush, for the better fitting of which to the axletree, it is
bored out of the solid, and made quite air-tight upon the pin; and for
retaining the oil, it is left close at the out-head D.

[Illustration: 1169 1170]

_Fig._ 1169. represents a collet, made of metal, turned perfectly true,
the least diameter of which is made the same with that part of the
axletree M, _fig._ 1167., and its greatest diameter the same with that
of the solid collar G, _fig._ 1167. This collet is made with a joint at
S, and opens at _p_. Two grooves are represented at _qq_, _qq_, which
are seen at the same letters in _fig._ 1170., as also the dovetail _r_,
in both figures.

_Fig._ 1170. is an edge view of the collet, _fig._ 1169.

[Illustration: 1171]

_Fig._ 1171. is a longitudinal section of an axletree arm, nave or bush,
and fastening. A, B, is the arm of the axletree, bored up the centre
from B to E. C, C, D, the nave, which answers also for the bush. P, S,
the collet (see _figs._ 1169. and 1170.), put into its place. _q_, _q_,
two steel pins, passing through the in-head of the bush, and filling up
the grooves in the collet. W, W, a caped hoop, sufficiently broad to
cover the ends of said pins, and made fast to the bush by screws. This
hoop, when so fastened to the bush, prevents the possibility of the pins
_q_, _q_, from getting out of their places. _u_, _u_, is a leather
washer, interposed betwixt the in-head of the bush and the larger solid
collar of the axletree, to prevent the escape of oil at the in-head. K,
is a screw, the head of which is near the letter K, in _fig._ 1167. This
screw being undone, and oil poured into the hole, it flows down the bore
in the centre of the axletree arm, and fills the space B, left by the
arm being about one inch shorter than the bore of the bush, and the
screw, being afterwards replaced, keeps all tight. In putting on the
wheel, a little oil ought to be put into the space betwixt the collet
P, S, and the larger collar. The collar P, S, being movable round the
axletree arm, and being made fast to the bush by means of the two pins
_q_, _q_, revolves along with the bush, acting against the solid collar
G, of the arm, and keeps the wheel fast to the axletree, until by
removing the caped hoop W, W, and driving out the pins _q_, _q_, the
collet becomes disengaged from the bush.

The dovetail, seen upon the collet at _r_, _fig._ 1170., has a
corresponding groove cut in the bush, to receive it, in consequence of
which the wheel must of necessity be put on so that the collet and pins
fit exactly. These wheels very rarely require to be taken off, and they
will run a thousand miles without requiring fresh oiling.

The spokes of the wheel, made of malleable iron, are screwed into the
bush or nave at C, C, _figs._ 1168. 1171., all round. The felloes,
composed merely of two bars of iron, bent into a circle edgeways, are
put on, the one on the front, the other on the back, of the spokes,
which have shoulders on both sides to support the felloes, and all three
are attached together by rivets through them. The space between the two
iron rings forming the felloes, should be filled up with light wood, the
tire then put on, and fastened to the felloes by bolts and glands
clasping both felloes.

This is a carriage without a mortise or tenon, or wooden joint of any
kind. It is, at an average, one-seventh lighter than any of those built
on the ordinary construction.

The design of Mr. W. Mason’s patent invention, of 1827, is to give any
required pressure to the ends of what are called mail axletrees, in
order to prevent their shaking in the boxes of the wheels. This object
is effected by the introduction of leather collars in certain parts of
the box, and by a contrivance, in which the outer cap is screwed up, so
as to bear against the end of the axletree with any degree of tightness,
and is held in that situation, without the possibility of turning round,
or allowing the axletree to become loose.

[Illustration: 1172 1173]

_Fig._ 1172. shows the section of the box of a wheel, with the end of
the axletree secured in it. The general form of the box, and of the
axle, is the same as other mail axles, there being recesses in the box
for the reception of oil. At the end of the axle, a cap _a_, is
inserted, with a leather collar enclosed in it, bearing against the end
of the axle; which cap, when screwed up sufficiently tight, is held in
that situation by a pin or screw passed through the cap _a_, into the
end of the iron box; a representation of this end of the iron box being
shown at _fig._ 1173.

In the cap _a_, there is also a groove for conducting the oil to the
interior of the box, with a screw at the opening, to prevent it running
out as the wheel goes round.

The particular claims of improvement are, the leather collar against the
end of the axle; the pin going through one of the holes in the end of
the box, to fix it; and the channel for conducting the oil.

Mr. Mason’s patent, of August, 1830, applies also to the boxes and axles
of that construction of carriage wheels which are fitted with the so
called mail-boxes; but part of the invention applies to other axles.

[Illustration: 1174 1175 1176]

_Fig._ 1174. represents the nave of a wheel, with the box for the axle
within it, both shown in section longitudinally; _fig._ 1175. is a
section of the axle, taken in the same direction; and _fig._ 1176.
represents the screw cap and oil-box, which attaches to the outer
extremity of the axle-box. Supposing the parts were put together, that
is, the axle inserted into the box, then the intention of the different
parts will be perceived.

The cylindrical recess _a_, in the box of the nave, is designed to fit
the cylindrical part of the axle _b_; and the conical part _c_, of the
axle, to shoulder up against a corresponding conical cavity in the box,
with a washer of leather to prevent its shaking. A collar _d_, formed by
a metallic ring, fits loosely upon a cylindrical part of the axle, and
is kept there by a flange or rim, fixed behind the cone _c_. Several
strong pins _f_, _f_, are cast into the back part of the box; which
pins, when the wheel is attached, pass through corresponding holes in
the collar _d_; and nuts being screwed on to the ends of the pins _f_,
behind the collar, keep the wheel securely attached to the axle. The
screw-cap _g_, is then inserted into the recess _h_, at the outer part
of the box, its conical end and small tube _i_, passing into the recess
_k_, in the end of the axle.

The parts being thus connected, the oil contained within the cap _g_,
will flow through the small tube _i_, in its end, into the recess or
cylindrical channel _l_, within the axle, and will thence pass through a
small hole in the side of the axle, into the cylindrical recess _a_, of
the box; and then lodging in the groove and other cavities within the
box, will lubricate the axle as the wheel goes round. There is also a
small groove cut on the outside of the axle, for conducting the oil, in
order that it may be more equally distributed over the surface and the
bearings. This construction of the box and axle, as far as the
lubrication goes, may be applied to the axles of wheels in general; but
that part of the invention which is designed to give greater security in
the attachment of the wheel to the carriage, applies particularly to
mail axles.

[Illustration: 1177 1178 1179 1180 1181]

Mr. William Mason’s patent invention for wheel carriages, of August,
1831, will be understood by reference to the annexed figures. _Fig._
1177. is a plan showing the fore-axletree bed _a_, _a_, of a
four-wheeled carriage, to which the axletrees _b_, _b_, are jointed at
each end; _fig._ 1178. is an enlarged plan; and _fig._ 1179. an
elevation, or side view of one end of the said fore-axletree bed, having
a Collinge’s axletree jointed to the axletree bed, by means of the
cylindrical pin or bolt _c_, which passes through and turns in a
cylindrical hole _d_, formed at the end of the axletree bed, shown also
in the plan view, _fig._ 1180., and section, _fig._ 1181.

[Illustration: 1182 1183 1184]

The axletree _b_, is firmly united with the upper end _e_, of the pin or
bolt _c_; and to the lower end of it, which is squared, the guide piece
_f_, is also fitted, and secured by the screw _g_, and cap or nut _h_,
seen in _fig._ 1179., and in section in _fig._ 1182. There are leather
washers _i_, _i_, let into recesses made to receive them in the parts
_a_, _b_, and _f_, the intent of which is to prevent the oil from
escaping that is introduced through the central perpendicular hole seen
in _fig._ 1182., which hole is closed by means of a screw inserted into
it. The oil is diffused, or spread over the surface of the cylinder _c_,
by means of a side branch leading from the bottom of the hole into a
groove formed around the cylinder, and also by means of two longitudinal
gaps or cavities made within the hole, as shown in _figs._ 1180. and
1181. The guide piece _f_, is affixed at right angles with the axletree
_b_, as shown in _fig._ 1178., and turns freely and steadily in the
cylindrical hole _d_, made to receive one end of the iron fore-axletree
bed _a_. In like manner, the opposite fore axletree _b_, _fig._ 1177.,
is jointed to the other end of the iron fore-axletree bed. The outer
ends of the guide pieces _f_, _f_, are jointed to the splinter-bar _n_,
_fig._ 1181, as follows:--_Fig._ 1183. is a plan, and _fig._ 1184. a
section of the joint _o_, in _fig._ 1177., shown on an enlarged scale; a
cylindrical pin or bolt _c_, is firmly secured in the splinter-bar, and
round the lower part of the said pin or bolt the guide piece _f_, turns,
and is made fast in its place by the screw _g_, and screwed nut _h_.

[Illustration: 1185 1186 1187 1188 1189 1190]

Oil is conveyed to the lower part of the cylindrical pin _c_, in a
similar manner to that already described, and two leather washers are
likewise furnished, to prevent its escape. The connecting joint at the
opposite end of the splinter-bar _n_, is constructed in a similar
manner. The futchel or socket _p_, _p_, for the pole of the carriage,
must also be jointed to the middle of the fore-axletree bed and
splinter-bar, in a similar manner. The swingletrees _q_, _q_, _fig._
1177., are likewise jointed in the same way to the splinter-bar. _Fig._
1185. is a side view of these parts. The fore wheels of the carriage,
_fig._ 1177., are furnished with cast-iron boxes, as usual. The dotted
lines show the action of the pole _p_, _p_, upon the splinter-bar _n_,
and as communicated through the latter to the guide pieces _f_, _f_,
connected with the axletrees _b_, _b_, so as to lock the wheels _r_,
_r_, as shown in that figure.

The axletree may be incased in the woodwork of the fore-bed of the
carriage, as usual, and as shown by dotted lines in the back end view
thereof, _fig._ 1186.; and the framing _s_, _fig._ 1187., may be affixed
firmly upon the said woodwork, in any fit and proper manner, as well as
the fore-springs _t_, _t_, shown in _figs._ 1186. and 1187., and
likewise in the side view, _fig._ 1188. In certain cases it may be
desirable to fix the cylindrical pin or bolt _c_, firmly in the
splinter-bar _n_, in the manner shown in _figs._ 1189. and 1190.; the
swingletrees _q_, _q_, and guide pieces _f_, _f_, turning freely above
and below upon the said pin or bolt, and secured in their places thereon
by screws and screwed nuts, oil being also supplied through holes formed
in both ends of the said pin or bolt, and leather washers provided, as
in the above-described instances.

Mr. Gibbs, engineer, and Mr. Chaplin, coach-maker, obtained a patent, in
1832, for the construction of a four-wheeled carriage which shall be
enabled to turn within a small compass, by throwing the axles of all the
four wheels simultaneously into different positions. They effect this
object by mounting each wheel upon a separate jointed axle, and by
connecting the free ends of the four axles by jointed rods or chains,
with the pole and splinter-bar in front of the carriage.

[Illustration: 1191 1192 1193]

To fix the ends of the spokes of wheels to the felloe or rim, with
greater security than had been effected by previous methods, is the
object of a contrivance for which William Howard obtained a patent, in
February, 1830. _Fig._ 1191. shows a portion of a wheel constructed on
this new method; _a_, is the nave, of wood; _b_, _b_, _b_, wooden
spokes, inserted into the nave in the usual way; _c_, _c_, is the rim or
felloe, intended to be formed by one entire circle of wrought iron; _d_,
and _e_, _e_, are the shoes or blocks, of cast iron, for receiving the
ends of the spokes, which are secured by bolts to the rim on the inner
circumference. The cap of the block _d_, is removed, for the purpose of
showing the internal form of the block; _e_, _e_, have their caps fixed
on, as they would appear when the spokes are fitted in. One of the caps
or shoes is shown detached, upon a larger scale, at _fig._ 1192., by
which it will be perceived that the end of the spoke is introduced into
the shoe on the side. It is proposed that the end of the spoke shall not
reach quite to the end of the recess formed in the block, and that it
shall be made tight by a wedge driven in. The wedge piece is to be of
wood, as _fig._ 1193., with a small slip of iron within it; and a hole
is perforated in the back of the block or shoe, for the wedge to be
driven through. When this is done, the ends of the spokes become
confined and tight; and the projecting extremities of the wedges being
cut off, the caps are then attached on the face of the block, as at _e_,
_e_, by pins riveted at their ends, which secures the spokes, and
renders it impossible for them to be loosened by the vibrations as the
wheel passes over the ground. One important use of the wedges, is to
correct the eccentric figure of the wheel, which may be readily forced
out in any part that may be out of the true form, by driving the wedge
up further; and this, it is considered, will be a very important
advantage, as the nearer a wheel can be brought to a true circle, the
easier it will run upon the road. The periphery of the wheel is to be
protected by a tire, which may be put on in pieces, and bolted through
the felloe; or it may be made in one ring, and attached, while hot, in
the usual way.

Mr. Reedhead’s patent improvements in the construction of carriages, are
represented in the following figures. They were specified in July, 1833.

[Illustration: 1194 1195 1196 1197]

_Fig._ 1194. is a plan or horizontal view of the fore part of a
carriage, intended to be drawn by horses, showing the fore wheels in
their position when running in a straight course; _fig._ 1195. is a
similar view, showing the wheels as locked, when in the act of turning;
_fig._ 1196. is a front end elevation of the same; _fig._ 1197. is a
section taken through the centre of the fore axletree; and _fig._ 1198.
is a side elevation of the general appearance of a stage-coach, with the
improvements appended: _a_, _a_, are two splinter-bars, with their
roller-bolts, for connecting the traces of the harness; these
splinter-bars are attached, by the bent irons _b_, _b_, to two short
axletrees or axle-boxes _c_, _c_, which carry the axles of the fore
wheels _d_, _d_, and turn upon vertical pins or bolts _e_, _e_, passed
through the fore axletree _f_, the splinter-bars and axle-boxes being
mounted so as to move parallel to each other, the latter partaking of
any motion given to the splinter-bars by the horses in drawing the
carriage forward, and thereby producing the locking of the wheels, as
shown _fig._ 1195.; and in order that the two wheels, and their axles
and axle-boxes, together with the splinter-bars _a_, _a_, may move
simultaneously, the latter are connected by pivots to the end of the
links or levers _g_, _g_, which are attached to the arms _i_, _i_, which
receive the pole of the coach by a hinge-joint or pin _h_; the arms _i_,
_i_, turning on a vertical fulcrum-pin _k_, passed through the main
axletree, _f_, as the pole is moved from one side to the other.

[Illustration: 1198 1199 1200]

The axles _o_, _o_, are firmly fixed into the naves of the wheels, as
represented in the side view of a wheel detached, at _fig._ 1200., the
axles being mounted so as to revolve within their boxes in the following
manner:--The axle-boxes, which answer the purpose of short axletrees,
are formed of iron, and consist of one main or bottom plate _l_, seen
best in _figs._ 1200. and 1199.; upon this bottom plate is formed the
chamber _m_, _m_, carrying the two anti-friction rollers _n_, _n_, which
turn on short axles passed through the sides and partition at the upper
part of the chambers. These anti-friction rollers bear upon the
cylindrical parts of the axle _o_, of each wheel, and support the weight
of the coach; _p_, is a bearing firmly secured in the axle-box to the
plate _l_, for the end of the axle _o_, to run in, the axle being
confined in its proper situation by a collar and screw-nut on its end;
_e_, is the vertical pin or bolt before mentioned, upon which the
axle-bar turns when the wheels are locking, which bolt is enlarged
within the box, and has an eye for the axle to pass through, being
firmly secured to the plate _l_, and also to the sides of the box.
_Fig._ 1200. is a plan or horizontal view of an axle and its box,
belonging to one of the fore wheels; a piece _q_, is fixed to the under
side of the main axletree, which supports the ends of the plates _l_,
and thereby relieves the pins _e_, _e_, of the strain they would
otherwise have to withstand. The axles of the hind wheels are mounted
upon similar plates _l_, _l_, with bearings and chambers with
anti-friction rollers; but as these are not required to lock, the plates
_l_, _l_, are fixed on to the under side of the hind axletree by
screw-nuts; there are small openings or doors, which can be removed for
the purpose of unscrewing the nuts and collars of the bearings _p_, when
the wheel is required to be taken off the carriage, when the axle can be
withdrawn from the boxes. If it should be thought necessary, other
chambers with friction rollers, may be placed on the under side of the
plate _l_, to bear up the end of the axles, and relieve the bearing _p_.
In order to stop or impede the progress of a carriage in passing down
hills, there is a grooved friction or brake wheel _t_, fixed, by clamps
or otherwise, on to the spokes of one of the hind wheels; _u_, is a
brake-band or spring, of metal, encircling the friction wheel, one end
of which band is fixed into the standard _v_, upon the hind axletree,
and the other end connected by a joint to the shorter end of the lever
_w_, which has its fulcrum in the standard _v_; this lever extends up to
the hind seat of the coach, as shown in _fig._ 1198., and is intended to
be under the command of the guard or passengers of the coach, and when
descending a hill, or on occasion of the horses running away, the longer
end of the lever is to be depressed, which will raise the shorter end,
and, consequently, bring the band or spring _u_, in contact with the
surface of the friction wheel, and thereby retard its revolution, and
prevent the coach travelling too fast; or, instead of attaching the
friction brake to the hind wheel, as represented in _fig._ 1198., it may
be adapted to the fore wheels, and the end of the lever brought up to
the side of the foot-board, or under it, and within command of the
coachman, the standard which carries the fulcrum being made to move upon
a pivot, to accommodate the locking of the wheels. It will be observed,
that by these improved constructions of the carriage, and mode of
locking the patentee is enabled to use much larger fore wheels than in
common, and that the splinter-bars will always be in the position of
right angles with the track or way of the horses in drawing the
carriage, by which they are much relieved, and always pull in a direct
and equal manner.

A manifest defect in all four-wheeled carriages, involving vast
superfluous friction, is the small size of the front wheels; a defect
which has existed ever since Walter Rippon made “the first hollow
_turning_ coach with pillars and arches for her majesty Queen Mary,
being then her servant,” until the railroad era, when our engineers
remedied the defect by equalizing the wheels, at the expense of another
defect--sacrificing the power of turning, and thus producing
great lateral friction; whence a train of evil consequences
result:--necessarily increased strength, and consequently increased
weight of the carriages; increased power and weight of the engine to
draw them, and overcome the friction; and, of course, increased strength
of rails, and greater solidity of railway.

These defects are at last remedied by an invention patented by Mr.
William Adams, author of a work entitled “English Pleasure Carriages.”
Instead of placing the perch-bolt, or turning centre, as is commonly
done, over the front axle, he places it at a convenient distance
_between_ the front and hind axles; so that when turning the carriage
the front wheels, instead of turning _beneath_ the body, as is common,
turn outside of it, and the driver’s seat turns with them; thus giving
him a perfect command over his horses in all positions, instead of the
usual dangerous plan, which renders a driver liable to be pulled off his
box by a restive horse, when in the act of turning. A carriage
constructed on Mr. Adams’ plan may also be driven round a corner at full
speed, without any risk of overturning, as the weight is equally poised
on the axles in all positions. It is well known that the oversetting of
stage coaches usually takes place when turning a corner, the momentum
urging the vehicle in a right line, while the horses are pulling at an
angle. By the new arrangement the front wheels may be made equal to the
hind ones, or of any desirable height, and at the same time the body may
be kept as low as may be thought convenient, even almost close to the
ground, if desired. Thus two important objects, hitherto deemed
incompatible, are combined--high wheels and a low centre of gravity.
These carriages are therefore essentially safety carriages, while the
friction is reduced to a minimum. The principle, in its various
modifications, is applicable to every variety of carriage, both those of
the simply useful kind, and those where beauty of form and colour are
prime requisites.

Another most important part of Mr. Adams’ invention, is his new mode of
spring suspension; applying the principle of the bow and string, for the
first time, to obviate the effects of concussion in wheel carriages. All
the springs hitherto in use for wheel carriages, have been friction
springs, composed of long sliding surfaces, uncertain in their action,
and liable to quick destruction by rust. But Mr. Adams’ springs are
essentially elastic, being formed of single plates abutting endways, so
that all friction is removed, and they can be hermetically sealed within
paint to prevent their corrosion. He has various modes of applying the
bow, either single or double, above or below the axle; but one most
important feature is, that the axle being attached to the flexible cords
or braces, the concussion which affects the wheels, either laterally,
vertically, or in the line of progress, is perfectly intercepted,
without the unpleasant oscillation experienced in carriages where the
same purpose is accomplished by the use of the curved or C spring. Mr.
Adams’ brace being, at the same time, a non-conductor of sound, the
rattling of the wheels does not annoy the rider as in ordinary
carriages. His springs are equally applicable to vehicles with two and
four wheels.

The advantages of these carriages may be thus summed up:--A great
diminution of the total weight; a diminution of resistance in draught
equal to about one third; increase of safety to the riders; increased
durability of the vehicle; absence of noise and vibration; absence of
oscillation.

To these qualities, so desirable to all, and especially those of
delicate nervous temperament, may be added--greater economy, both in the
first cost and maintenance.

The _whirling_ public so blindly follows fashionable caprice in the
choice of a carriage, as to have hitherto paid too little attention to
this fundamental improvement; but many intelligent individuals have
fully verified its practical reality. Having inspected various forms of
two-wheeled and four-wheeled carriages, in the patentee’s premises in
Drury Lane, I feel justified in recommending them as being constructed
on the soundest mechanical principles; and have no doubt, that if reason
be allowed to decide upon their merits, they will ere long be
universally preferred by all who seek for easy-moving, safe, and
comfortable vehicles.


WHETSLATE, is a massive mineral of a greenish-gray colour; feebly
glimmering; fracture, slaty or splintery; fragments tabular; translucent
on the edges; feels rather greasy; and has a spec. grav. of 2·722. It
occurs in beds, in primitive and transition slates. Very fine varieties
of whetslate are brought from Turkey, called _honestones_, which are in
much esteem for sharpening steel instruments.


WHEY (_Petit lait_, Fr.; _Molken_, Germ.); is the greenish-gray liquor
which exudes from the curd of milk. Scheele states, that when a pound of
milk is mixed with a spoonful of proof spirit, and allowed to become
sour, the whey filtered off, at the end of a month or a little more, is
a good vinegar, devoid of lactic acid.


WHISKEY; is dilute alcohol, distilled from the fermented worts of malt
or grains.


WHITE LEAD, _Carbonate of lead, or Ceruse_. (_Blanc de plomb_, Fr.;
_Bleiweiss_, Germ.) This preparation is the only one in general use for
painting wood and the plaster walls of apartments white. It mixes well
with oil, without having its bright colour impaired, spreads easily
under the brush, and gives a uniform coat to wood, stone, metal, &c. It
is employed either alone, or with other pigments, to serve as their
basis, and to give them body. This article has been long manufactured
with much success at Klagenfurth in Carinthia, and its mode of
preparation has been lately described with precision by Marcel de
Serres. The great white-lead establishments at Krems, whence, though
incorrectly, the terms _white of Kremnitz_ became current on the
continent, have been abandoned.

1. The lead comes from Bleyberg; it is very pure, and particularly free
from contamination with iron, a point essential to the beauty of its
factitious carbonate. It is melted in ordinary pots of cast iron, and
cast into sheets of varying thickness, according to the pleasure of the
manufacturer. These sheets are made by pouring the melted lead upon an
iron plate placed over the boiler; and whenever the surface of the metal
begins to consolidate, the plate is slightly sloped to one side, so as
to run off the still liquid metal, and leave a lead sheet of the desired
thinness. It is then lifted off like a sheet of paper; and as the iron
plate is cooled in water, several hundred weight of lead can be readily
cast in a day. In certain white-lead works these sheets are one
twenty-fourth of an inch thick; in others, half that quantity; in some,
one of these sheets takes up the whole width of the conversion-box; in
others, four sheets are employed. It is of consequence not to smooth
down the faces of the leaden sheets; because a rough surface presents
more points of contact, and is more readily attacked by acid vapours,
than a polished one.

2. These plates are now placed so as to expose an extensive surface to
the acid fumes, by folding each other over a square slip of wood. Being
suspended by their middle, like a sheet of paper, they are arranged in
wooden boxes, from 4-1/2 to 5 feet long, 12 to 14 inches broad, and from
9 to 11 inches deep. The boxes are very substantially constructed; their
joints being mortised; and whatever nails are used, being carefully
covered. Their bottom is made tight with a coat of pitch about an inch
thick. The mouths of the boxes are luted over with paper, in the works
where fermenting horsedung is employed as the means of procuring heat,
to prevent the sulphuretted and phosphuretted hydrogen from injuring the
purity of the white lead. In Carinthia it was formerly the practice, as
also in Holland, to form the lead sheets into spiral rolls, and to place
them so coiled up in the chests; but this plan is not to be recommended,
because these rolls present obviously less surface to the action of the
vapours, are apt to fall down into the liquid at the bottom, and thus to
impair the whiteness of the lead. The lower edges of the sheets are
suspended about two inches and a half from the bottom of the box; and
they must not touch either one another or its sides, for fear of
obstructing the vapours in the first case, or of injuring the colour in
the second. Before introducing the lead, a peculiar acid liquor is put
into the box, which differs in different works. In some, the proportions
are four quarts of vinegar, with four quarts of wine-lees; and in
others, a mixture is made of 20 pounds of wine-lees, with 8-1/2 pounds
of vinegar, and a pound of carbonate of potash. It is evident that in
the manufactories where no carbonate of potash is employed in the
mixture, and no dung for heating the boxes, it is not necessary to lute
them.

3. The mixture being poured into the boxes, and the sheets of lead
suspended within them, they are carried into a stove-room, to receive
the requisite heat for raising round the lead the corrosive vapours, and
thus converting it into carbonate. This apartment is heated generally by
stoves, is about 9 feet high, 30 feet long, and 24 feet wide, or of such
a size as to receive about 90 boxes. It has only one door.

The heat should never be raised above 86° Fahr.; and it is usually kept
up for 15 days, in which time the operation is, for the most part,
completed. If the heat be too high, and the vapours too copious, the
carbonic acid escapes in a great measure, and the metallic lead, less
acted upon, affords a much smaller product.

When the process is well managed, as much carbonate of lead is obtained,
as there was employed of metal; or, for 300 pounds of lead, 300 of
ceruse are procured, besides a certain quantity of metal after the
crusts are removed, which is returned to the melting-pot. The mixture
introduced into the boxes serves only once; and if carbonate of potash
has been used, the residuary matter is sold to the hatters.

4. When the preceding operation is supposed to be complete, the sheets,
being removed from the boxes, are found to have grown a quarter of an
inch thick, though previously not above a twelfth of that thickness. A
few pretty large crystals of acetate of lead are sometimes observed on
their edges. The plates are now shaken smartly, to cause the crust of
carbonate of lead formed on their surfaces to fall off. This carbonate
is put into large cisterns, and washed very clean. The cistern is of
wood, most commonly of a square shape, and divided into from seven to
nine compartments. These are of equal capacity, but unequal height, so
that the liquid may be made to overflow from one to the other. Thereby,
if the first chest is too full, it decants its excess into the second,
and so on in succession. See RINSING MACHINE.

The water poured into the first chest, passes successively into the
others, a slight agitation being meanwhile kept up, and there deposits
the white lead diffused in it proportionally, so that the deposit of the
last compartment is the finest and lightest. After this washing, the
white lead receives another, in large vats, where it is always kept
under water. It is lastly lifted out in the state of a liquid paste,
with wooden spoons, and laid on drying-tables to prepare it for the
market.

The white lead of the last compartment is of the first quality, and is
called on the continent silver white. It is employed in fine painting.

When white lead is mixed in equal quantities with ground sulphate of
barytes, it is known in France and Germany by the name of Venice white.
Another quality, adulterated with double its weight of sulphate of
barytes, is styled Hamburgh white; and a fourth, having three parts of
sulphate to one of white lead, gets the name of Dutch white. When the
sulphate of barytes is very white, like that of the Tyrol, these
mixtures are reckoned preferable for certain kinds of painting, as the
barytes communicates opacity to the colour, and protects the lead from
being speedily darkened by sulphureous smoke or vapours.

The high reputation of the white lead of Krems was by no means due to
the barytes, for the first and whitest quality was mere carbonate of
lead. The freedom from silver of the lead of Villach, a very rare
circumstance, is one cause of the superiority of its carbonate; as well
as the skilful and laborious manner in which it is washed, and separated
from any adhering particle of metal or sulphuret.

In England, lead is converted into carbonate in the following way.--The
metal is cast into the form of a network grating, in moulds about 15
inches long, and 4 or 5 broad. Several rows of these are placed over
cylindrical glazed earthen pots, about 4 or 5 inches in diameter,
containing some treacle-vinegar, which are then covered with straw;
above these pots another range is piled, and so in succession, to a
convenient height. The whole are imbedded in spent bark from the
tan-pit, brought into a fermenting state by being mixed with some bark
used in a previous process. The pots are left undisturbed under the
influence of a fermenting temperature for eight or nine weeks. In the
course of this time the lead gratings become, generally speaking,
converted throughout into a solid carbonate, which when removed is
levigated in a proper mill, and elutriated with abundance of pure water.
The plan of inserting coils of sheet lead into earthenware pipkins
containing vinegar, and imbedding the pile of pipkins in fermenting
horsedung and litter, is now little used; because the coil is not
uniformly acted on by the acid vapours, and the sulphuretted hydrogen
evolved from the dung is apt to darken the white lead.

In the above processes, the conversion of lead into carbonate, seems to
be effected by keeping the metal immersed in a warm, humid atmosphere,
loaded with carbonic and acetic acids; and hence a pure vinegar does not
answer well; but one which is susceptible, by its spontaneous
decomposition in these circumstances, of yielding carbonic acid. Such
are tartar, wine-lees, molasses, &c.

Another process has lately been practised to a considerable extent in
France, though it does not afford a white lead equal in body and opacity
to the products of the preceding operations. M. Thenard first
established the principle, and MM. Brechoz and Leseur contrived the
arrangements of this new method, which was subsequently executed on a
great scale by MM. Roard and Brechoz.

A subacetate of lead is formed by digesting a cold solution of
uncrystallized acetate, over litharge, with frequent agitation. It is
said that 65 pounds of purified pyrolignous acid, of specific gravity
1·056, require, for making a neutral acetate, 58 pounds of litharge; and
hence, to form the subacetate, three times that quantity of base, or 174
pounds, must be used. The compound is diluted with water, as soon as it
is formed, and being decanted off quite limpid, is exposed to a current
of carbonic acid gas, which, uniting with the two extra proportions of
oxide of lead in the subacetate, precipitates them in the form of a
white carbonate, while the liquid becomes a faintly acidulous acetate.
The carbonic acid may be extricated from chalk, or other compounds, or
generated by combustion of charcoal, as at Clichy; but in the latter
case, it must be transmitted through a solution of acetate of lead
before being admitted into the subacetate, to deprive it of any
particles of sulphuretted hydrogen. When the precipitation of the
carbonate of lead is completed, and well settled down, the supernatant
acetate is decanted off, and made to act on another dose of litharge.
The deposit being first rinsed with a little water, this washing is
added to the acetate; after which the white lead is thoroughly
elutriated. This repetition of the process may be indefinitely made; but
there is always a small loss of acetate, which must be repaired, either
directly or by adding some vinegar.

In order to obtain the finest white lead by the process with earthen
pots containing vinegar buried in fermenting tan, and covered by a
grating of lead, the metal should be so thin as to be entirely
convertible into carbonate; for whenever any of it remains, it is apt to
give a gray tint to the product: if the temperature of the fermenting
mass is less than 90° Fahr., some particles of the metal will resist the
action of the vinegar, and degrade the colour; and if it exceeds 122°,
the white verges into yellow, in consequence of some carbonaceous
compound being developed from the principles of the acetic acid. The
dung and tan have been generally supposed to act in this process by
supplying carbonic acid, the result of their fermentation; but it is now
said that this explanation is inexact, because the best white lead can
be obtained by the entire exclusion of air from the pots in which the
carbonation of the metal is carried on. We are thence led to conclude
that the lead is oxidized at the expense of the oxygen of the vinegar,
and carbonated by the agency of its oxygen and carbon; the hydrogen of
the acid being left to associate itself with the remaining oxygen and
carbon, so as to constitute an ethereous compound: thus, supposing the
three atoms of oxygen to form, with one of lead and one of carbon, an
atom of carbonate, then the remaining three atoms of carbon and three of
hydrogen would compose olefiant gas.

It is customary on the continent to mould the white lead into conical
loaves, before sending them into the market. This is done by stuffing
well-drained white lead into unglazed earthen pots, of the requisite
size and shape, and drying it to a solid mass, by exposing these pots in
stove-rooms. The moulds being now inverted on tables, discharge their
contents, which then receive a final desiccation; and are afterwards put
up in pale-blue paper, to set off the white colour by contrast. Nothing
in all the white-lead process is so injurious as this pot operation; a
useless step, fortunately unknown in Great Britain. Neither greasing the
skin, nor wearing thick gloves, can protect the operators from the
diseases induced by the poisonous action of the white lead; and hence
they must be soon sent off to some other department of the work.

It has been supposed that the differences observed between the ceruse of
Clichy and the common kinds, depend on the greater compactness of the
particles of the latter, produced by their slower aggregation; as also,
according to M. Robiquet, on the former containing considerably less
carbonic acid. See _infrà_.

[Illustration: 1201]

Mr. Ham proposed, in a patent dated June, 1826, to produce white lead
with the aid of the following apparatus, _a_, _a_, (_fig._ 1201.) are
the side-walls of a stove-room, constructed of bricks; _b_, is the floor
of bricks laid in Roman cement; _c_, _c_, are the side-plates, between
which and the walls, a quantity of refuse tanner’s bark, or other
suitable vegetable matter, is to be introduced. The same material is to
be put also into the lower part at _d_ (upon a false bottom of grating?)
The tan should rise to a considerable height, and have a series of
strips of sheet lead _e_, _e_, _e_, placed upon it, which are kept apart
by blocks or some other convenient means, with a space open at one end
of the plates, for the passage of the vapours; but above the upper
plates, boards are placed, and covered with tan, to confine them there.
In the lower part of the chamber, coils of steam-pipe _f_, _f_, are laid
in different directions to distribute heat; _g_, is a funnel-pipe, to
conduct vinegar into the lower part of the vessel; and _h_, is a cock to
draw it off, when the operation is suspended. The acid vapours raised by
the heat, pass up through the spent bark, and on coming into contact
with the sheets of lead, corrode them. The quantity of acid liquor
should not be in excess; a point to be ascertained by means of the small
tube _i_, at top, which is intended for testing it by the tongue. _k_,
is a tube for inserting a thermometer, to watch the temperature, which
should not exceed 170° Fahr. I am not aware of what success has attended
this patented arrangement. The heat prescribed is far too great.

A magnificent factory has been recently erected at West Bromwich, near
Birmingham, to work a patent lately granted to Messrs. Gossage and
Benson, for making white lead by mixing a small quantity of acetate of
lead in solution with slightly damped litharge, contained in a long
stone trough, and passing over the surface of the trough currents of hot
carbonic acid, while its contents are powerfully stirred up by a
travelling-wheel mechanism. The product is afterwards ground and
elutriated, as usual. The carbonic acid gas is produced from the
combustion of coke. I am told that 40 tons of excellent white lead are
made weekly by these chemico-mechanical operations.

Messrs. Button and Dyer obtained a patent about a year and a half ago,
for making white lead by transmitting a current of purified carbonic
acid gas, from the combustion of coke, through a mixture of litharge and
nitrate of lead, diffused and dissolved in water, which is kept in
constant agitation and ebullition by steam introduced through a
perforated coil of pipes at the bottom of the tub. The carbonate of lead
is formed here upon the principle of Thenard’s old process with the
subacetate; for the nitrate of lead forms with the litharge a
subnitrate, which is forthwith transformed into carbonate and neutral
nitrate, by the agency of the carbonic acid gas. I have discovered that
all sorts of white lead produced by precipitation from a liquid, are in
a semi-crystalline condition; appear, therefore, semi-transparent, when
viewed in the microscope; and do not cover so well as white lead made by
the process of vinegar and tan, in which the lead has remained always
solid during its transition from the blue to the white state; and hence
consists of opaque particles.

A patent was obtained, in December, 1833, by John Baptiste Constantine
Torassa, and others, for making white lead by agitating the granulated
metal, or shot, in trays or barrels, along with water, and exposing the
mixture of lead-dust and water to the air, to be oxidized and
carbonated. It is said that upwards of 100,000_l._ have been expended at
Chelsea, by a joint stock company, in a factory constructed for
executing the preceding most operose and defective process; which has
been, many years ago, tried without success in Germany. I am convinced
that the whole of these recent projects for preparing white lead, are
inferior in economy, and quality of produce, to the old Dutch process,
which may be so arranged as to convert sheets of blue lead thoroughly
into the best white lead, within the space of 12 days, at less expense
of labour than by any other plan.

White lead, as obtained by precipitation from the acetate, subacetate,
and subnitrate, is a true carbonate of the metal, consisting of one
prime equivalent of lead 104, one of oxygen 8, and one of carbonic acid
22; whose sum is 134, the atomic weight of the compound; or, of lead,
77·6; oxygen, 6; carbonic acid, 16·4; in 100 parts. It has been
supposed, by some authors, that the denser and better-covering white
lead of Krems and Holland is a kind of subcarbonate, containing only 9
per cent. of carbonic acid; but this view of the subject does not accord
with my researches.


WICK (_Mèche_, Fr.; _Docht_, Germ.); is the spongy cord, usually made of
soft spun cotton threads, which by capillary action, draws up the oil in
lamps, or the melted tallow or wax in candles, in small successive
portions, to be burned. In common wax and tallow candles, the wick is
formed of parallel threads; in the stearine candles, the wick is plaited
upon the braiding machine, moistened with a very dilute sulphuric acid,
and dried, whereby as it burns, it falls to one side and consumes
without requiring to be snuffed; in the patent candles of Mr. Palmer,
one-tenth of the wick is first imbued with subnitrate of bismuth ground
up with oil, the whole is then bound round in the manner called
_gimping_; and of this wick, twice the length of the intended candle is
twisted double round a rod, like the _caduceus of Mercury_. This rod
with its coil being inserted in the axis of the candle mould, is to be
enclosed by pouring in the melted tallow; and when the tallow is set,
the rod is to be drawn out at top, leaving the wick in the candle. As
this candle is burned, the ends of the double wick stand out sideways
beyond the flame; and the bismuth attached to the cotton being acted on
by the oxygen of the atmosphere, causes the wick to be completely
consumed, and, therefore, saves the trouble of snuffing it.


WINCING-MACHINE, is the English name of the dyer’s reel, which he
suspends horizontally, by the ends of its iron axis in bearings, over
the edge of his vat, so that the line of the axis, being placed over the
middle partition in the copper, will permit the piece of cloth which is
wound upon the reel, to descend alternately into either compartment of
the bath, according as it is turned by hand to the right or the left.
For an excellent self-acting or mechanical wince, see DYEING.


WINE, is the fermented juice of the grape. In the more southern states
of Europe, the grapes, being more saccharine, afford a more abundant
production of alcohol, and stronger wines, as exemplified in the best
port, sherry, and madeira. The influence of solar heat upon the vines
may, however, be mitigated by growing them to moderate heights on level
ground, and by training them in festoons under the shelter of trees. In
the more temperate climates, such as the district of Burgundy, the finer
flavoured wines are produced; and there the vines are usually grown upon
hilly slopes fronting the south, with more or less of an easterly or
westerly direction, as on the Côte d’Or, at a distance from marshes,
forests, and rivers, whose vapours might deteriorate the air. The plains
of this district, even when possessing a similar or analogous soil, do
not produce wines of so agreeable a flavour. The influence of
temperature becomes very manifest in countries further north, where, in
consequence of a few degrees of thermometric depression, the production
of generous agreeable wine becomes impossible.

The land most favourable to the vine is light, easily permeable to
water, but somewhat retentive by its composition; with a sandy subsoil,
to allow the excess of moisture to drain readily off. Calcareous soils
produce the highly esteemed wines of the Côte d’Or; a granitic debris
forms the foundation of the lands where the Hermitage wines are grown;
siliceous soil interspersed with flints furnishes the celebrated wines
of Château-Neuf, Ferté, and La Gaude; schistose districts afford also
good wine, as that called _la Malgue_. Thus we see that lands differing
in chemical composition, but possessed of the proper physical qualities,
may produce most agreeable wines; and so also may lands of like chemical
and physical constitution produce various kinds of wine, according to
their varied exposure. As a striking example of these effects, we may
adduce the slopes of the hills which grow the wines of Montrachet. The
insulated part towards the top furnishes the wine called _Chevalier
Montrachet_, which is less esteemed, and sells at a much lower price,
than the delicious wine grown on the middle height, called _true
Montrachet_. Beneath this district, and in the surrounding plains, the
vines afford a far inferior article, called _bastard Montrachet_. The
opposite side of the hills produces very indifferent wine. Similar
differences, in a greater or less degree, are observable relatively to
the districts which grow the Pomard, Volnay, Beaune, Nuits, Vougeot,
Chambertin, Romanée, &c. Every where it is found, that the reverse side
of the hill, the summit, and the plain, although generally consisting of
like soil, afford inferior wine to the middle southern slopes.

_Amelioration of the soil._--When the vine lands are too light or too
dense, they may be modified, within certain limits, by introducing into
them either argillaceous or siliceous matter. Marl is excellent for
almost all grounds which are not previously too calcareous, being alike
useful to open dense soils, and to render porous ones more retentive.

_Manure._--For the vine, as well as all cultivated plants, a manure
supplying azotized or animal nutriment may be used with great advantage,
provided care be taken to ripen it by previous fermentation, so that it
may not, by absorption in too crude a state, impart any disagreeable
odour to the grape; as sometimes happens to the vines grown in the
vicinity of great towns, like Paris, and near Argenteuil. There is a
compost used in France, called _animalized black_, of which from 1/3 to
1/2 of a litre (old English quart) serves sufficiently to fertilize the
root of one vine, when applied every year, or two years. An excess of
manure, in rainy seasons especially, has the effect of rendering the
grapes large and insipid.

The ground is tilled at the same time as the manure is applied, towards
the month of March; the plants are then dressed, and the props are
inserted. The weakness of the plants renders this practice useful; but
in some southern districts, the stem of the vine, when supported at a
proper height, acquires after a while sufficient size and strength to
stand alone. The ends of the props or poles are either dipped in tar, or
charred, to prevent their rotting. The bottom of the stem must be
covered over with soil, after the spring rains have washed it down. The
principal husbandry of the vineyard consists in digging or ploughing to
destroy the weeds, and to expose the soil to the influence of the air,
during the months of May, June, and occasionally in August.

The vintage, in the temperate provinces, generally takes place about the
end of September; and it is always deteriorated whenever the fruit is
not ripe enough before the 15th or 20th of October; for, in this case,
not only is the must more acid, and less saccharine, but the
atmospherical temperature is apt to fall so low during the nights, as to
obstruct more or less its fermentation into wine. The grapes should be
plucked in dry weather, at the interval of a few days after they are
ripe; being usually gathered in baskets, and transported to the vats in
dorsels, sufficiently tight to prevent the juice from running out.
Whenever a layer about 14 or 15 inches thick has been spread on the
bottom of the vat, the treading operation begins, which is usually
repeated after macerating the grapes for some time, when an incipient
fermentation has softened the texture of the skin and the interior
cells. When the whole bruised grapes are collected in the vat, the
juice, by means of a slight fermentation, reacts, through the acidity
thus generated, upon the colouring-matter of the husks, and also upon
the tannin contained in the stones and the fruit-stalks. The process of
fermentation is suffered to proceed without any other precaution, except
forcing down from time to time the pellicles and pedicles floated up by
the carbonic acid to the top; but it would be less apt to become
acetous, were the mouths of the vats covered. With this view, M. Sebille
Auger introduced with success his elastic bung in the manufacture of
wine in the department of the Maine-et-Loire.

With whatever kind of apparatus the fermentation may have been
regulated, as soon as it ceases to be tumultuous, and the wine is not
sensibly saccharine or muddy, it must be racked off from the lees, by
means of a spigot, and run into the ripening tuns. The marc being then
gently squeezed in a press, affords a tolerably clear wine, which is
distributed among the tuns in equal proportions; but the liquor obtained
by stronger pressure, is reserved for the casks of inferior wine.

In the south of France the fermentation sometimes proceeds too slowly,
on account of the must being too saccharine; an accident which is best
counteracted by maintaining a temperature of about 65° or 68° F., in the
tun-room. When the must, on the other hand, is too thin, and deficient
in sugar, it must be partially concentrated by rapid boiling, before the
whole can be made to ferment into a good wine. By boiling up a part of
the must for this purpose, the excess of ferment is at the same time
destroyed. Should this concentration be inconvenient, a certain
proportion of sugar must be introduced, immediately after racking it
off.

The specific gravity of must varies with the richness and ripeness of
the grapes which afford it; being in some cases so low as 1·0627, and in
others so high as 1·1283. This happens particularly in the south of
France. In the district of the Necker in Germany, the specific gravity
varies from 1·050 to 1·090; in Heidelberg, from 1·039, to 1·091; but it
varies much in different years.

After the fermentation is complete, the vinous part consists of water,
alcohol, a colouring-matter, a peculiar aromatic principle, a little
undecomposed sugar, bitartrate and malate of potash, tartrate of lime,
muriate of soda, and tannin; the latter substances being in small
proportion.

It is known that a few green grapes are capable of spoiling a whole cask
of wine, and therefore they are always allowed to become completely
ripe, and even sometimes to undergo a species of slight fermentation,
before being plucked, which completes the development of the saccharine
principle. At other times the grapes are gathered whenever they are
ripe, but are left for a few days on wicker-floors, to sweeten, before
being pressed.

In general the whole vintage of the day is pressed in the evening, and
the resulting must is received in separate vats. At the end usually of 6
or 8 hours, if the temperature be above 50° F., and if the grapes have
not been too cold when plucked, a froth or scum is formed at the
surface, which rapidly increases in thickness. After it acquires such a
consistence as to crack in several places, it is taken off with a
skimmer, and drained; and the thin liquor is returned to the vat. A few
hours afterwards another coat of froth is formed, which is removed in
like manner, and sometimes a third may be produced. The regular vinous
fermentation now begins, characterized by air-bubbles rising up the
sides of the staves, with a peculiar whizzing as they break at the
surface. At this period all the remaining froth should be quickly
skimmed off, and the clear subjacent must, be transferred into barrels,
where it is left to ripen by a regular fermentation.

The white wines, which might be disposed to become stringy, from a
deficient supply of tannin, may be preserved from this malady by a due
addition of the footstalks of ripe grapes. The tannin, while it tends to
preserve the wines, renders them also more easy to clarify, by the
addition of white of egg, or isinglass.

The white wines should be racked off as soon as the first frosts have
made them clear, and at the latest by the end of the February moon. By
thus separating the wine from the lees, we avoid, or render of little
consequence, the fermentation which takes place on the return of spring,
and which, if too brisk, would destroy all its sweetness, by decomposing
the remaining portion of sugar.

The characteristic odour possessed by all wines, in a greater or less
degree, is produced by a peculiar substance, which possesses the
characters of an essential oil. As it is not volatile, it cannot be
confounded with the aroma of wine. When large quantities of wine are
distilled, an oily substance is obtained towards the end of the
operation. This may also be procured from the wine lees which are
deposited in the casks after the fermentation has commenced. It forms
one 40,000th part of the wine; and consists of a peculiar new acid, and
ether, each of which has been called the _œnanthic_. The acid is
analogous to the fatty acids, and the ether is liquid, but insoluble in
water. The acid is perfectly white when pure, of the consistence of
butter at 60°, melts with a moderate heat, reddens litmus, and dissolves
in caustic and carbonated alkalis, as well as in alcohol and ether.
Œnanthic ether is colourless, has an extremely strong smell of wine,
which is almost intoxicating when inhaled, and a powerful disagreeable
taste. _Liebig and Pelouze._

_Sparkling wines._--In the manufacture of these, black grapes of the
first quality are usually employed, especially those gathered upon the
vine called by the French _noirien_, cultivated on the best exposures.
As it is important, however, to prevent the colouring-matter of the skin
from entering into the wine, the juice should be squeezed as gently and
rapidly as possible. The liquor obtained by a second and third pressing
is reserved for inferior wines, on account of the reddish tint which it
acquires. The marc is then mixed with the grapes of the red-wine vats.

The above nearly colourless must, is immediately poured into tuns or
casks, till about three-fourths of their capacity are filled, when
fermentation soon begins. This is allowed to continue under the control
of the elastic bung, above mentioned, for about 15 days, and then
three-fourths of the casks are filled up with wine from the rest. The
casks are now closed by a bung secured with a piece of hoop iron nailed
to two contiguous staves. The casks should be made of new wood, but not
of oak--though old white wine casks are occasionally used.

In the month of January the clear wine is racked off, and is fined by a
small quantity of isinglass dissolved in old wine of the same kind.
Forty days afterwards a second fining is required. Sometimes a third may
be useful, if the lees be considerable. In the month of May the clear
wine is drawn off into bottles, taking care to add to each of them a
small measure of what is called _liquor_, which is merely about 3 per
cent. of a syrup made by dissolving sugar-candy in white wine. The
bottles being filled, and their corks secured by packthread and wire,
they are laid on their sides, in this month, with their mouths sloping
downwards at an angle of about 20 degrees, in order that any sediment
may fall into the neck. At the end of 8 or 10 days, the inclination of
the bottles is increased, when they are slightly tapped, and placed in a
vertical position; so that after the lees are all collected in the neck,
the cork is partially removed for an instant, to allow the sediment to
be expelled by the pressure of the gas. If the wine be still muddy in
the bottles, along with a new dose of _liquor_, a small quantity of
fining should be added to each, and the bottles should be placed again
in the inverted position. At the end of two or three months, the
sediment collected over the cork, is dexterously discharged; and if the
wine be still deficient in transparency, the same process of fining must
be repeated.

Sparkling wine (_vin mousseux_), prepared as above described, is fit for
drinking usually at the end of from 18 to 30 months, according to the
state of the seasons. It is in Champagne that the lightest, most
transparent, and most highly flavoured wines, have been hitherto made.
The breakage of the bottles in these sparkling wines amounts frequently
to 30 per cent., a circumstance which adds greatly to their cost of
production.

Weak wines of bad growths ought to be consumed within 12 or 15 months
after being manufactured; and should be kept meanwhile in cool cellars.
White wines of middling strength ought to be kept in casks constantly
full, and carefully excluded from contact of air, and the racking off
should be done as quickly as possible. As the most of them are injured
by too much fermentation, this process should be so regulated as always
to leave a little sugar undecomposed. It is useful to counteract the
absorption of oxygen, and the consequent tendency to acidity, by burning
a sulphur match in the casks into which they are about to be run. This
is done by hooking the match to a bent wire, kindling and suspending it
within the cask through the bung-hole. Immediately on withdrawing the
match, the cask should be corked, if the wine be not ready for transfer.
If the burning sulphur be extinguished on plunging it into the cask, it
is a proof of the cask being unsound, and unfit for receiving the wine;
in which case it should be well cleansed, first with lime-water, then
with very dilute sulphuric acid, and lastly with boiling water.

Wine-cellars ought to be dry at bottom, floored with flags, have windows
opening to the north, be so much sunk below the level of the adjoining
ground as to possess a nearly uniform temperature in summer and winter;
and be at such a distance from a frequented highway or street as not to
suffer vibration from the motion of carriages.

Wines should be racked off in cool weather; the end of February being
the fittest time for light wines. Strong wines are not racked off till
they have stood a year or eighteen months upon the lees, to promote
their slow or insensible fermentation. A syphon well managed serves
better than a faucet to draw off wine clear from the sediment. White
wines, before being bottled, should be fined with isinglass; red wines
are usually fined with whites of eggs beat up into a froth, and mixed
with two or three times their bulk of water. But some strong wines,
which are a little harsh from excess of tannin, are fined with a little
sheep or bullock’s blood. Occasionally a small quantity of sweet glue is
used for this purpose.

_The following maladies of wines_, are certain accidental
deteriorations, to which remedies should be speedily applied.

_La-pousse_ (pushing out of the cask), is the name given to a violent
fermentative movement, which occasionally supervenes after the wine has
been run off into the casks. If these have been tightly closed, the
interior pressure may increase to such a degree as to burst the hoops,
or cause the seams of the staves or ends to open. The elastic bungs
already described, will prevent the bursting of the casks; but something
must be done to repress the fermentation, lest it should destroy the
whole of the sugar, and make the wine unpalatably harsh. One remedy is,
to transfer the wine into a cask previously fumigated with burning
sulphur; another is, to add to it about one thousandth part of sulphite
of lime; and a third, and perhaps the safest, is to introduce half a
pound of mustard-seed into each barrel. At any rate the wines should be
fined whenever the movements are allayed, to remove the floating ferment
which has been the cause of the mischief.

_Turning sour._--The production of too much acid in a wine, is a proof
of its containing originally too little alcohol, of its being exposed
too largely to the air, or to vibrations, or to too high a temperature
in the cellar. The best thing to be done in this case is, to mix it with
its bulk of a stronger wine in a less advanced state, to fine the
mixture, to bottle it, and to consume it as soon as possible, for it
will never prove a good keeping wine. This _distemper_ in wines formerly
gave rise to the very dangerous practice of adding litharge as a
sweetener; whereby a quantity of acetate or sugar of lead was formed in
the liquor, productive of the most deleterious consequences to those who
drunk of it. In France, the regulations of police, and the enlightened
_surveillance_ of the council of salubrity, have completely put down
this gross abuse. The saturation of the acid by lime and other alkaline
bases has generally a prejudicial effect, and injures more or less the
vinous flavour and taste.

_Ropiness or viscidity of wines._--The cause of this phenomenon, which
renders wine unfit for drinking, was altogether unknown, till M.
François, an apothecary of Nantes, demonstrated that it was owing to an
azotized matter, analogous to _gliadine_ (gluten); and in fact it is the
white wines, especially those which contain the least tannin, which are
subject to this malady. He also pointed out the proper remedy, in the
addition of tannin under a rather agreeable form, namely, the bruised
berries of the mountain-ash (_sorbier_), in a somewhat unripe state; of
which one pound, well stirred in, is sufficient for a barrel. After
agitation, the wine is to be left in repose for a day or two, and then
racked off. The tannin by this time will have separated the azotized
matter from the liquor, and removed the ropiness. The wine is to be
fined and bottled off.

_The taste of the cask_, which sometimes happens to wine put into casks
which had remained long empty, is best remedied by agitating the wine
for some time with a spoonful of olive oil. An essential oil, the chief
cause of the bad taste, combines with the fixed oil, and rises with it
to the surface.

According to a statement in the _Dictionnaire Technologique_, the annual
produce of a hectare of vineyard, upon the average of 113 years, in the
district of Volnay, is 1779 litres, which fetch 0·877 francs each, or
200 francs the piece of 228 litres, amounting in all to 1672 francs.
Deducting for expenses and taxes (_contributions_) 572 francs, there
remain 1100 francs of net proceeds; and as the value of the capital may
be estimated at 23,000 francs, the profit turns out to be no more than 5
per cent. The net proceeds in the growths of Beaune, Nuits, &c., does
not exceed 600 francs per hectare (2·4 acres), and therefore is
equivalent to only 2-1/2 per cent. upon the capital.

The quantity of alcohol contained in different wines, has been made the
subject of elaborate experiments by Brande and Fontenelle; but as it
must evidently vary with different seasons, the results can be received
merely as approximative. The only apparatus required for this research,
is a small still and refrigeratory, so well fitted up as to permit none
of the spirituous vapours to be dissipated. The distilled liquor should
be received in a glass tube, graduated into one hundred measures, of
such capacity as to contain the whole of the alcohol which the given
measure of wine employed is capable of yielding. In the successive
experiments, the quantity of wine used, and of spirit distilled over,
being the same in volume, the relative densities of the latter will show
at once the relative strengths of the wines. A very neat small apparatus
has been contrived for the purpose of analyzing wines in this manner, by
M. Gay Lussac. It is constructed, and sold at a moderate price, by M.
Collardeau, No. 56, Rue Faubourg St. Martin, Paris. The proportion given
by Brande (Table I.), has been reduced to the standard of absolute
alcohol by Fesser; and that by Fontenelle (Table II.), to the same
standard by Schubarth; as in the following tables:--

TABLE I.

  +------------------+---------+------------------+
  |                  |         |  100 measures,   |
  |                  |         |contain at 60° F. |
  |Name of the Wine. |Sp. grav.+---------+--------+
  |                  |         | Alcohol |Absolute|
  |                  |         |of 0·825.|alcohol.|
  +------------------+---------+---------+--------+
  |Port Wine         | 0·97616 |  21·40  |  19·82 |
  |  Do.             | 0·97200 |  25·83  |  23·92 |
  |              Mean| 0·97460 |  23·49  |  21·75 |
  |Madeira           | 0·97810 |  19·34  |  17·91 |
  |  Do.             | 0·97333 |  21·42  |  22·61 |
  |Sherry            | 0·97913 |  18·25  |  17·00 |
  |  Do.             | 0·97700 |  19·83  |  18·37 |
  |Bordeaux, Claret  | 0·97410 |  12·91  |  11·95 |
  |  Do.             | 0·97092 |  16·32  |  15·11 |
  |Calcavella        | 0·97920 |  18·10  |  16·76 |
  |Lisbon            | 0·97846 |  18·94  |  17·45 |
  |Malaga            | 0·98000 |  17·26  |  15·98 |
  |Bucellas          | 0·97890 |  18·49  |  17·22 |
  |Red Madeira       | 0·97899 |  18·40  |  17·04 |
  |Malmsey           | 0·98090 |  16·40  |  15·91 |
  |Marsala           | 0·98190 |  15·26  |  14·31 |
  |  Do.             | 0·98000 |  17·26  |  15·98 |
  |Champagne (rose)  | 0·98608 |  11·30  |  10·46 |
  |  Do.    (white)  | 0·98450 |  12·80  |  11·84 |
  |Burgundy          | 0·98300 |  14·53  |  13·34 |
  |  Do.             | 0·98540 |  11·95  |  11·06 |
  |White Hermitage   | 0·97990 |  17·43  |  16·14 |
  |Red do.           | 0·98495 |  12·32  |  11·40 |
  |Hock              | 0·98290 |  14·37  |  13·31 |
  |  Do.             | 0·98873 |   8·88  |   8·00 |
  |Vin de Grave      | 0·98450 |  12·80  |  11·84 |
  |Frontignac        | 0·98452 |  17·79  |  11·84 |
  |Côte-Rotí         | 0·98495 |  12·27  |  11·36 |
  |Roussillon        | 0·98005 |  17·24  |  15·96 |
  |Cape Madeira      | 0·97924 |  18·11  |  16·77 |
  |Muscat            | 0·97913 |  18·25  |  17·00 |
  |Constantia        | 0·97770 |  19·75  |  18·29 |
  |Tinto             | 0·98399 |  13·30  |  12·32 |
  |Schiraz           | 0·98176 |  15·52  |  14·35 |
  |Syracuse          | 0·98200 |  15·28  |  14·15 |
  |Nice              | 0·98263 |  14·63  |  13·64 |
  |Tokay             | 0·98760 |   9·88  |   9·15 |
  |Raisin wine       | 0·97205 |  25·77  |  23·86 |
  |Drained grape wine| 0·97925 |  18·11  |  16·77 |
  |Lachrymæ Christi  |    --   |  19·70  |  18·24 |
  |Currant wine      | 0·97696 |  20·55  |  19·03 |
  |Gooseberry wine   | 0·98550 |  11·84  |  10·96 |
  |Elder wine }      |         |         |        |
  |Cyder      }      | 0·98760 |   9·87  |   9·14 |
  |Perry      }      |         |         |        |
  |Brown Stout       | 0·99116 |   6·80  |   6·30 |
  |Ale               | 0·98873 |   8·88  |   8·00 |
  |Porter            |    --   |   4·20  |   3·89 |
  |Rum               | 0·93494 |  53·68  |  49·71 |
  |Hollands          | 0·93855 |  51·60  |  47·77 |
  |Scotch whiskey    |    --   |  54·32  |  50·20 |
  |Irish whiskey     |    --   |  53·90  |  49·91 |
  +------------------+---------+---------+--------+

TABLE II.

  +--------------------------------+--------+
  |                                |Absolute|
  |       Name of the Wine.        |alcohol.|
  +--------------------------------+--------+
  |_Roussillon (Eastern Pyrenees.)_|        |
  |Rive-saltes       18 yrs. old   |  9·156 |
  |Banyulls          18            |  9·223 |
  |Collyouvre        15            |  9·080 |
  |Salces            10            |  8·580 |
  |                                |        |
  |   _Department of the Aude._    |        |
  |Fitou and Leucaté 10            |  8·568 |
  |Lapalme           10            |  8·790 |
  |Sijeau             8            |  8·635 |
  |Narbonne           8            |  8·379 |
  |Lezignan          10            |  8·173 |
  |Mirepeisset       10            |  8·589 |
  |Carcasonne         8            |  7·190 |
  |                                |        |
  |   _Department of l’Herault._   |        |
  |Nissau             9            |  7·896 |
  |Beziers            8            |  7·728 |
  |Montagnac         10            |  8·108 |
  |Mèze              10            |  7·812 |
  |Montpellier        5            |  7·413 |
  |Lunel              8            |  7·564 |
  |Frontignan         5            |  7·098 |
  |Red Hermitage      4            |  5·838 |
  |White   do.                     |  7·056 |
  |Burgundy           4            |  6·195 |
  |Grave              3            |  5·838 |
  |Champagne (sparkling)           |  5·880 |
  |  Do. white  do.                |  5·145 |
  |  Do. rose                      |  4·956 |
  |Bordeaux                        |  6·186 |
  |Toulouse                        |  5·027 |
  +--------------------------------+--------+


WINE, FAMILY, may be made by the following recipe:--Take black, red,
white currants, ripe cherries (black hearts are the best), and
raspberries, of each an equal quantity. To 4 pounds of the mixed fruit,
well bruised, put 1 gallon of clear soft water; steep three days and
nights, in open vessels, frequently stirring up the magma; then strain
through a hair sieve; press the residuary pulp to dryness, and add its
juice to the former. In each gallon of the mixed liquors dissolve 3
pounds of good yellow muscovado sugar; let the solution stand other
three days and nights, frequently skimming and stirring it up; then tun
it into casks, which should remain full, and purging at the bung-hole,
about two weeks. Lastly, to every 9 gallons, put 1 quart of good Cognac
brandy (but not the drugged imitations made in London with grain
whiskey), and bung down. If it does not soon become fine, a steeping of
isinglass may be stirred into the liquid, in the proportion of about
half an ounce to 9 gallons. I have found that the addition of an ounce
of cream of tartar to each gallon of the fermentable liquor, improves
the quality of the wine, and makes it resemble more nearly the produce
of the grape.


WINE-STONE, is the deposit of crude tartar, called argal, which settles
on the sides and bottoms of wine casks.


WIRE-DRAWING. (_Tréfilerie_, Fr.; _Draht-ziehen_, _Drahtzug_, Germ.)
When an oblong lump of metal is forced through a series of progressively
diminishing apertures in a steel plate, so as to assume in its cross
section the form and dimensions of the last hole, and to be augmented in
length at the expense of its thickness, it is said to be wire-drawn. The
piece of steel called the _draw-plate_ is pierced with a regular
gradation of holes, from the largest to the smallest; and the machine
for overcoming the lateral adhesion of the metallic particles to one
another, is called the _draw-bench_. The pincers which lay hold of the
extremity of the wire, to pull it through the successive holes, are
adapted to bite it firmly, by having the inside of the jaws, cut like a
file. For drawing thick rods of gilt silver down into stout wire, the
hydraulic press has been had recourse to with advantage.

[Illustration: 1202]

_Fig._ 1202. represents a convenient form of the draw-bench, where the
power is applied by a toothed wheel, pinion, and rack-work, moved by the
hands of one or two men working at a winch; the motion being so
regulated by a fly-wheel, that it does not proceed in fits and starts,
and cause inequalities in the wire. The metal requires to be annealed,
now and then, between successive drawings, otherwise it would become too
hard and brittle for further extension. The reel upon which it is wound
is sometimes mounted in a cistern of sour small beer, for the purpose of
clearing off, or loosening at least, any crust of oxide formed in the
annealing, before the wire enters the draw-plate.

When, for very accurate purposes of science or the arts, a considerable
length of uniform wire is to be drawn, a plate with one or more jewelled
holes, that is, filled with one or more perforated rubies, sapphires, or
chrysolites, can alone be trusted to, because the holes even in the best
steel become rapidly wider by the abrasion. Through a hole in a ruby
0·0033 of an inch in diameter, a silver wire 170 miles long has been
drawn, which possessed at the end, the very same section as at the
beginning; a result determined by weighing portions of equal length, as
also by measuring it with a micrometer. The hole in an ordinary
draw-plate of soft steel becomes so wide, by drawing 14,000 fathoms of
brass wire, that it requires to be narrowed before the original sized
wire can be again obtained.

Wire, by being diminished one-half, one-third, one-fourth, &c., in
diameter, is augmented in length respectively, four, nine, sixteen
times, &c. The speed with which it may be prudently drawn out, depends
upon the ductility and tenacity of the metal; but may be always
increased the more the wire becomes attenuated, because its particles
progressively assume more and more of the filamentous form, and
accommodate themselves more readily to the extending force. Iron and
brass wires, of 0·3 inch in diameter, bear drawing at the rate of from
12 to 15 inches per second; but when of 0·025 (1/40) of an inch, at the
rate of from 40 to 45 inches in the same time. Finer silver and copper
wire may be extended from 60 to 70 inches per second.

By enclosing a wire of platinum within one of silver ten times thicker,
and drawing down the compound wire till it be 1/300 of an inch, a wire
of platinum of 1/3000 of an inch, will exist in its centre, which may be
obtained apart, by dissolving the silver away in nitric acid. This
pretty experiment was first made by Dr. Wollaston.

The French draw-plates are so much esteemed, that one of the best of
them used to be sold in this country, during the late war, for its
weight in silver. The holes are formed with a steel punch; being made
large on that side where the wire enters, and diminishing with a regular
taper to the other side. In the act of drawing, they must be well
supplied with grease for the larger kinds of wire, and with wax for the
smaller.


WOAD (_Vouëde_, _Pastel_, Fr.; _Waid_, Germ; _Isatis tinctoria_, Linn.);
the _glastum_ of the antient Gauls and Germans; is an herbaceous plant
which was formerly much cultivated, as affording a permanent blue dye,
but it has been in modern times well nigh superseded by _indigo_. Pliny
says, “A certain plant which resembles _plantago_, called _glastum_, is
employed by the women and girls in Great Britain for dyeing their bodies
all over, when they assist at certain religious ceremonies; they have
then the colour of Ethiopians.”--_Hist. Nat._ cap. xxii. § 2.

When the arts, which had perished with the Roman empire, were revived,
in the middle ages, woad began to be generally used for dyeing blue, and
became an object of most extensive cultivation in many countries of
Europe. The environs of Toulouse and Mirepoix, in Upper Languedoc,
produced annually 40,000,000 pounds of the prepared woad, or pastel, of
which 200,000 bales were consumed at Bordeaux. Beruni, a rich
manufacturer of this drug, became surety for the payment of the ransom
of his king, Francis I., then the prisoner of Charles V. in Spain.

The leaves of woad are fermented in heaps, to destroy certain vegetable
principles injurious to the beauty of the dye, as also to elaborate the
indigoferous matter present, before they are brought into the market;
but they should be carefully watched during this process. Whenever the
leaves have arrived at maturity, a point judged of very differently in
different countries, they are stripped off the plant, a cropping which
is repeated as often as they shoot, being three or four times in
Germany, and eight or ten times in Italy. The leaves are dried as
quickly as possible, but not so much as to become black; and they are
ground before they get quite dry. The resulting paste is laid upon a
sloping pavement, with gutters for conducting the juice which exudes
into a tank; the heap being tramped from time to time, to promote the
discharge of the juice. The woad ferments, swells, and cracks in many
places, which fissures must be closed; the whole being occasionally
watered. The fermentation is continued for twenty or thirty days, in
cold weather; and if the leaves have been gathered dry, as in Italy, for
four months. When the fermented heap has become moderately dry, it is
ground again, and put up in cakes of from one to three pounds; which are
then fully dried, and packed up in bundles for the market. Many dyers
subject the pastel to a second fermentation.

1,600 square toises (fathoms) of land afford in two cuttings at least
19,000 pounds of leaves, of which weight four-fifths are lost in the
fermentation, leaving 3,880 pounds of pastel, in loaves or cakes. When
good, it has rather a yellow, or greenish-yellow, than a blue colour; it
is light, and slightly humid; it gives to paper a pale-green trace; and
improves by age, in consequence of an obscure fermentation; for if kept
four years, it dyes twice as much as after two years. According to
Hellot, 4 pounds of Guatimala indigo produce the same effect as 210
pounds of the pastel of Albi. At Quins, in Piedmont, the dyers estimate
that 6 pounds of indigo are equivalent to 300 of pastel; but Chaptal
thinks the indigo underrated.

Pastel will dye blue of itself, but it is commonly employed as a
fermentative addition to the proper blue vat, as described under INDIGO.

Fresh woad, analyzed by Chevreul, afforded, in 100 parts, 65·4 of juice.
After being steeped in water, the remaining mass yielded, on expression,
29·65 of liquid; being in whole, 95·05 parts, leaving 4·95 of ligneous
fibre. The juice, by filtration, gave 1·95 of green fecula. 100 parts of
fresh woad, when dried, are reduced to 13·76 parts. Alcohol, boiled upon
dry woad, deposits, after cooling, indigo in microscopic needles; but
these cannot be separated from the vegetable albumine, which retains a
greenish-gray colour.


WOLFRAM, is the native tungstate of iron and manganese, a mineral which
occurs in primitive formations, along with the ores of tin, antimony,
and lead, in the Bohemian Erzgebirge, in Cornwall, Switzerland, North
America, &c. It is used by chemists for obtaining tungstic acid and
tungsten.


WOOD (_Bois_, Fr.; _Holz_, Germ.); is the hard but porous tissue between
the pith and the bark of trees and shrubs, through which the chief part
of the juices are conducted from the root towards the branches and
leaves, during the life of the vegetable. The ligneous fibre is the
substance which remains, after the plant has been subjected to the
solvent action of ether, alcohol, water, dilute acids, and caustic
alkaline lyes. It is considered by chemists that dry timber consists, on
an average, of 96 parts of fibrous, and 4 of soluble matter, in 100; but
that these proportions vary somewhat with the seasons, the soil, and the
plant. All kinds of wood sink in water, when placed in a basin of it
under the exhausted receiver of an air-pump; showing their specific
gravity to be greater than 1·000. That of fir and maple is stated, by
chemical authors, to be 1·46; and that of oak and beech, at 1·53; but I
believe them to have all the same spec. grav. as the fibre of flax;
namely, 1·50, as determined by me some years ago.[71]

  [71] “From the small difference found by experiment between the
  specific gravity of flax (1·50), and of cotton (1·47), I am inclined
  to think that the density of both may be considered to be equal.” or
  1·50.--_Philosophy of Manufactures_, 2d edition, pp. 97, 98, 99.

Wood becomes snow-white, when exposed to the action of chlorine;
digested with sulphuric acid, it is transformed first into gum, and, by
ebullition with water, afterwards into grape-sugar; with concentrated
nitric acid, it grows yellow, loses its coherence, falls into a
pulverulent mass, but eventually dissolves, and is converted into oxalic
acid; with strong caustic alkaline lyes, in a hot state, it swells up
excessively, dissolves into a homogeneous liquid, and changes into a
blackish-brown mass, containing oxalic and acetic acids.

The composition of wood has been examined by Gay Lussac and Thenard, and
Dr. Prout. The first two chemists found it to consist, in 100 parts,
of--

              Oak.     Beech.
  Carbon      52·53    51·45
  Hydrogen     5·69     5·82
  Oxygen      41·78    42·73

According to Dr. Prout, the oxygen and hydrogen are in the exact
proportions to form water. Willow contains 50, and box 49·8 per cent. of
carbon; each containing, therefore, very nearly 44·444 of oxygen, and
5·555 of hydrogen. In the analyses of Gay Lussac and Thenard, there is a
great excess of hydrogen above what the oxygen requires to form water.
Authenrieth stated, some years ago, that he found that fine sawdust,
mixed with a sufficient quantity of wheat flour, made a coherent dough
with water, which formed an excellent food for pigs; apparently showing
that the digestive organs of this animal could operate the same sort of
change upon wood as sulphuric acid does.

TABLE of the DISTILLATION of ONE POUND of WOOD, dried, at 86° Fahr.

  +-------------------------+----------+-----------+---------+---------+
  |   Name of the wood.     |Weight of |One ounce  |Weight of|Weight of|
  |                         |wood acid.|of the acid|the com- |the char-|
  |                         |          |saturates  |bustible |coal.    |
  |                         |          |of carbon- |oil.     |         |
  |                         |          |ate of     |         |         |
  |                         |          |potash.    |         |         |
  +-------------------------+----------+-----------+---------+---------+
  |                         | _Ounces._| _Grains._ |_Ounces._|_Ounces._|
  |White birch              |   7      |     44    |  1-1/4  |  3-3/4  |
  |Red beech                |   7      |     44    |  1-1/2  |  3-3/4  |
  |Prick wood (spindle tree)|   7-1/2  |     40    |  1-3/4  |  3-1/2  |
  |Large leaved linden      |   6-3/4  |     41    |  2      |  3-3/4  |
  |Red or scarlet oak       |   7      |     40    |  1-1/2  |  4-1/4  |
  |White beech              |   6-1/2  |     40    |  1-3/4  |  3-3/4  |
  |Common ash               |   7-1/2  |     34    |  1-1/2  |  3-1/2  |
  |Horse chestnut           |   7-1/2  |     31    |  1-1/2  |  3-1/2  |
  |Italian poplar           |   7-1/4  |     30    |  1-1/2  |  3-3/4  |
  |Silver poplar            |   7-1/4  |     30    |  1-1/4  |  3-3/4  |
  |White willow             |   7-1/4  |     28    |  1-1/2  |  3-1/2  |
  |Root of the sassafras    |          |           |         |         |
  |laurel                   |   6-3/4  |     29    |  1-3/4  |  4-1/4  |
  |Wild service tree        |   7      |     28    |  1-3/4  |  3-1/2  |
  |Basket willow            |   8      |     27    |  1-1/2  |  3-1/2  |
  |Dogberry tree            |   7      |     27    |  2      |  3-1/2  |
  |Buckthorn                |   7-1/2  |     26    |  1-1/2  |  3-1/2  |
  |Logwood                  |   7-3/4  |     26    |  1-1/2  |  4      |
  |Alder                    |   7-1/4  |     22    |  1-1/2  |  3-1/2  |
  |Juniper                  |   7-1/4  |     23    |  1-3/4  |  3-1/2  |
  |White fir (deal)         |   6-1/2  |     23    |  2-1/4  |  3-1/2  |
  |Common pine wood         |   6-3/4  |     22    |  1-3/4  |  3-1/2  |
  |Savine tree              |   7      |     20    |  1-3/4  |  3-3/4  |
  |Red deal (pine)          |   6-1/2  |     18    |  2-1/4  |  3-3/4  |
  |Guiac wood               |   6      |     16    |  2-1/2  |  4-1/4  |
  +-------------------------+----------+-----------+---------+---------+


WOOF, is the same as WEFT.


WOOLLEN MANUFACTURE. In reference to textile fabrics, sheep’s wool is of
two different sorts, the short and the long stapled; each of which
requires different modes of manufacture in the preparation and spinning
processes, as also in the treatment of the cloth after it is woven, to
fit it for the market. Each of these is, moreover, distinguished in
commerce by the names of fleece wools and dead wools, according as they
have been shorn at the usual annual period from the living animal, or
are cut from its skin after death. The latter are comparatively harsh,
weak, and incapable of imbibing the dyeing principles, more especially
if the sheep has died of some malignant distemper. The annular pores,
leading into the tubular cavities of the filaments, seem, in this case,
to have shrunk and become obstructed. The time of year for
sheep-shearing most favourable to the quality of the wool, and the
comfort of the animal, is towards the end of June and beginning of
July;--the period when Lord Leicester holds his celebrated rural fête
for that interesting purpose.

The wool of the sheep has been surprisingly improved, by its domestic
culture. The _mouflon_ (_Ovis aries_), the parent stock from which our
sheep is undoubtedly derived, and which is still found in a wild state
upon the mountains of Sardinia, Corsica, Barbary, Greece, and Asia
Minor, has a very short and coarse fleece, more like hair than wool.
When this animal is brought under the fostering care of man, the rank
fibres gradually disappear; while the soft wool round their roots,
little conspicuous in the wild animal, becomes singularly developed. The
male most speedily undergoes this change, and continues ever afterwards
to possess far more power in modifying the fleece of the offspring, than
the female parent. The produce of a breed from a coarse-woolled ewe, and
a fine-woolled ram, is not of a mean quality between the two, but
half-way nearer that of the sire. By coupling the female thus generated,
with such a male as the former, another improvement of one-half will be
obtained, affording a staple three-fourths finer than that of the
grandam. By proceeding inversely, the wool would be as rapidly
deteriorated. It is, therefore, a matter of the first consequence in
wool husbandry, to exclude from the flock all coarse-fleeced rams.

Long wool is the produce of a peculiar variety of sheep, and varies in
the length of its fibres from 3 to 8 inches. Such wool is not carded
like cotton, but combed like flax, either by hand or appropriate
machinery. Short wool is seldom longer than 3 or 4 inches; it is
susceptible of carding and felting, by which processes the filaments
become first convoluted, and then densely matted together. The shorter
sorts of the combing wool are used principally for hosiery, though of
late years the finer kinds have been extensively worked up into merino
and mousseline-de-laine fabrics. The longer wools of the Leicestershire
breed are manufactured into hard yarns, for worsted pieces, such as
waistcoats, carpets, bombasines, poplins, crapes, &c.

The wool of which good broad cloth is made, should be not only shorter,
but, generally speaking, finer and softer than the worsted wools, in
order to fit them for the fulling process. Some wool-sorters and
wool-staplers acquire by practice great nicety of discernment in judging
of wools by the touch and traction of the fingers. Two years ago, I made
a series of observations upon different wools, and published the
results. The filaments of the finer qualities varied in thickness from
1/1100 to 1/1500 of an inch; their structure is very curious,
exhibiting, in a good achromatic microscope, at intervals of about 1/300
of an inch, a series of serrated rings, imbricated towards each other,
like the joints of _Equisetum_, or rather like the scaly zones of a
serpent’s skin. See _Philosophy of Manufactures_, _figs._ 11, 12., page
91. second edition.

There are four distinct qualities of wool upon every sheep; the finest
being upon the spine, from the neck to within 6 inches of the tail,
including one-third of the breadth of the back; the second covers the
flanks between the thighs and the shoulders; the third clothes the neck
and the rump; and the fourth extends upon the lower part of the neck and
breast down to the feet, as also upon a part of the shoulders and the
thighs, to the bottom of the hind quarter. These should be torn asunder,
and sorted, immediately after the shearing.

The harshness of wools is dependent not solely upon the breed of the
animal, or the climate, but is owing to certain peculiarities in the
pasture, derived from the soil. It is known, that in sheep fed upon
chalky districts, wool is apt to get coarse; but in those upon a rich
loamy soil, it becomes soft and silky. The ardent sun of Spain renders
the fleece of the Merino breed harsher than it is in the milder climate
of Saxony. Smearing sheep with a mixture of tar and butter, is deemed
favourable to the softness of their wool.

All wool, in its natural state, contains a quantity of a peculiar
potash-soap, secreted by the animal, called in this country the _yolk_;
which may be washed out by water alone, with which it forms a sort of
lather. It constitutes from 25 to 50 per cent. of the wool, being most
abundant in the Merino breed of sheep; and however favourable to the
growth of the wool on the living animal, should be taken out soon after
it is shorn, lest it injure the fibres by fermentation, and cause them
to become hard and brittle. After being washed in water, somewhat more
than lukewarm, the wool should be well pressed, and carefully dried.
England grows annually about 1,000,000 packs of wool, and imports
100,000 bags.

Wool imported into the United Kingdom, in 1836, 64,239,977 lbs.; in
1837, 48,356,121 lbs. Retained for home consumption, in 1836, 60,724,795
lbs.; in 1837, 43,148,297 lbs. Duty received, in 1836, _£_190,075; in
1837, _£_118,519.

Having premised these general observations on wool, I shall now proceed
to treat of its manufacture, beginning with that of wool-combing, or

THE WORSTED MANUFACTURE.

In this branch of business, a long stapled and firm fibre is required to
form a smooth level yarn, little liable to shrink, curl, or felt in
weaving and finishing the cloth. It must not be entangled by carding,
but stretched in lines as parallel as possible, by a suitable system of
_combing_, manual or mechanical.

When the long wool is brought into the worsted factory, it is first of
all washed by men with soap and water, who are paid for their labour by
the piece, and are each assisted by a boy, who receives the wool as it
issues from between the drying _squeezers_ (see BLEACHING). The boy
carries off the wool in baskets, and spreads it evenly upon the floor of
the drying-room, usually an apartment over the boilers of the
steam-engine, which is thus economically heated to the proper
temperature. The health of the boys employed in this business is found
to be not at all injured.

[Illustration: 1203]

The wool, when properly dried, is transferred to a machine called the
_plucker_, which is always superintended by a boy of 12 or 14 years of
age, being very light work. He lays the tresses of wool pretty evenly
upon the feed-apron, or table covered with an endless moving web of
canvas, which, as it advances, delivers the ends of the long tufts to a
pair of fluted rollers, whence it is introduced into a fanning
apparatus, somewhat similar to the _willow_ employed in the cotton
manufacture, which see. The filaments are turned out, at the opposite
end of this winnowing machine, straightened, cleaned, and ready for the
combing operation. According to the old practice of the trade, and still
for the finer descriptions of the long staple, according to the present
practice, the wool is carded by hand. This is far more severe labour
than any subservient to machinery, and is carried on in rooms rendered
close and hot by the number of stoves requisite to heat the combs, and
so enable them to render the fibres soft, flexible, and elastic. This is
a task at which only robust men are engaged. They use three implements:
1. a pair of combs for each person; 2. a post, to which one of the combs
can be fixed; 3. a comb-pot, or small stove for heating the teeth of the
combs. Each comb is composed either of two or three rows of pointed
tapering steel teeth, _b_, _fig._ 1203., disposed in two or three
parallel planes, each row being a little longer than the preceding. They
are made fast at the roots to a wooden stock or head _c_, which is
covered with horn, and has a handle _d_, fixed into it at right angles
to the lines of the teeth. The spaces between these two or three planes
of teeth, is about one-third of an inch at their bottoms, but somewhat
more at their tips. The first combing, when the fibres are most
entangled, is performed with the two-row toothed combs; the second or
finishing combing, with the three-row toothed.

[Illustration: 1204]

In the workshop a post is planted (_fig._ 1204.) upright, for resting
the combs occasionally upon, during the operation. An iron stem _g_,
projects from it horizontally, having its end turned up, so as to pass
through a hole in the handle of the comb. Near its point of insertion
into the post, there is another staple point _h_, which enters into the
hollow end of the handle; which, between these two catches, is firmly
secured to the post. The stove is a very simple affair, consisting
merely of a flat iron plate, heated by fire or steam, and surmounted
with a similar plate, at an interval sufficient to allow the teeth to be
inserted between them at one side, which is left open, while the space
between their edges, on the other sides, is closed to confine the heat.

In combing the wool, the workman takes it up in tresses of about four
ounces each, sprinkles it with oil, and rolls it about in his hands, to
render all the filaments equally unctuous. Some harsh dry wools require
one-sixteenth their weight of oil, others no more than a fortieth. He
next attaches a heated comb to the post, with its teeth pointed upwards,
seizes one-half of the tress of wool in his hands, throws it over the
teeth, then draws it through them, and thus repeatedly: leaving a few
straight filaments each time upon the comb. When the comb has in this
way collected all the wool, it is placed with its points inserted into
the cell of the stove, with the wool hanging down outside, exposed to
the influence of the heat. The other comb, just removed in a heated
state from the stove, is planted upon the post, and furnished in its
turn with the remaining two-ounce tress of wool; after which it
supplants the preceding at the stove. Having both combs now hot, he
holds one of them with his left hand over his knee, being seated upon a
low stool, and seizing the other with his right hand, he combs the wool
upon the first, by introducing the teeth of one comb into the wool stuck
in the other, and drawing them through it. This manipulation is
skilfully repeated, till the fibres are laid truly parallel, like a flat
tress of hair. It is proper to begin by combing the tips of the tress,
and to advance progressively, from the one end towards the other, till
at length the combs are worked with their teeth as closely together as
is possible, without bringing them into collision. If the workman
proceeded otherwise, he would be apt to rupture the filaments, or tear
their ends entirely out of one of the combs. The flocks left at the end
of the process, because they are too short for the comber to grasp them
in his hand, are called _noyls_. They are unfit for the worsted spinner,
and are reserved for the coarse cloth manufacture.

The wool finally drawn off from the comb, though it may form a uniform
tress of straight filaments, must yet be combed again at a somewhat
lower temperature, to prepare it perfectly for the spinning operation.
From ten to twelve slivers are then arranged in one parcel.

To relieve the workman from this laborious and not very salubrious task,
has been the object of many mechanical inventions. One of these,
considerably employed in this country and in France, is the invention of
the late Mr. John Collier, of Paris, for which a patent was obtained in
England, under the name of John Platt, of Salford, in November, 1827. It
consists of two comb-wheels, about ten feet in diameter, having hollow
iron spokes filled with steam, in order to keep the whole apparatus at a
proper combing heat. The comb forms a circle, made fast to the periphery
of the wheel, the teeth being at right angles to the plane of the wheel.
The shafts of the two wheels are mounted in a strong frame of cast iron;
not, however, in horizontal positions, but inclined at acute angles to
the horizon, and in planes crossing each other, so that the teeth of one
circular comb sweep with a steady obliquity over the teeth of the other,
in a most ingenious manner, with the effect of combing the tresses of
wool hung upon them. The proper quantity of long wool, in its ordinary
state, is stuck in handfuls upon the wheel, revolving slowly, by a boy,
seated upon the ground at one side of the machine. Whenever the wheel is
dressed, the machine is made to revolve more rapidly, by shifting its
driving-band on another pulley; and it is beautiful to observe the
delicacy and precision with which it smoothes the tangled tress. When
the wools are set in rapid rotation, the loose ends of the fleece, by
the centrifugal force, are thrown out, in the direction of radii, upon
the teeth of the other revolving comb-wheel, so as to be drawn out and
made truly straight. The operation commences upon the tips of the
tresses, where the wheels, by the oblique posture of their shafts, are
at the greatest distance apart; but as the planes slowly approach to
parallelism, the teeth enter more deeply into the wool, till they
progressively comb the whole length of its fibres. The machines being
then thrown out of geer, the teeth are stript of the tresses by the hand
of the attendant; the _noyls_, or short refuse wool, being also removed,
and kept by itself.

This operation being one of simple superintendence, not of handicraft
effort and skill, like the old combing of long wool, is now performed by
boys or girls of 13 and 14 years of age; and places in a striking point
of view the influence of automatic mechanism, in so embodying dexterity
and intelligence in a machine, as to render the cheap and tractable
labour of children a substitute for the high-priced and often refractory
exertions of workmen too prone to capricious combinations. The chief
precaution to be taken with this machine, is to keep the steam-joints
tight, so as not to wet the apartments, and to provide due ventilation
for the operatives.

[Illustration: 1205]

The following machine, patented by James Noble, of Halifax,
worsted-spinner, in February, 1834, deserves particular notice, as its
mode of operation adapts it well also for heckling flax. In _fig._ 1205.
the internal structure is exhibited. The frame-work _a_, _a_, supports
the axle of a wheel _b_, _b_, in suitable bearings on each side. To the
face of this wheel is affixed the eccentric or heart-wheel cam _c_, _c_.
On the upper part of the periphery of this cam or heart-wheel, a lever
_d_, _d_, bears merely by its gravity; one end of which lever is
connected by a joint to the crank _e_. By the rotation of the crank _e_,
it will be perceived that the lever _d_, will be slidden to and fro on
the upper part of the periphery of the eccentric or heart-wheel cam _c_,
the outer end of the lever _d_, carrying the upper or working comb or
needle-points _f_, as it moves, performing an elliptical curve, which
curve will be dependent upon the position of the heart-wheel cam _c_,
that guides it. A movable frame _g_, carries a series of points _h_,
which are to constitute the lower comb or frame of needles. Into these
lower needles the rough uncombed wool is to be fed by hand, and to be
drawn out and combed straight by the movements of the upper or working
comb.

As it is important, in order to prevent waste, that the ends of the wool
should be first combed out, and that the needle-points should be made to
penetrate the wool progressively, the movable frame _g_, is in the first
instance placed as far back as possible; and the action of the lever
_d_, during the whole operation, is so directed by the varying positions
of the cam-wheel, as to allow the upper comb to enter at first a very
little way only into the wool; but as the operation of combing goes on,
the frame with the lower combs is made to advance gradually, and the
relative positions of the revolving heart cam-wheel _c_, being also
gradually changed, the upper or working needles are at length allowed to
be drawn completely through the wool, for the purpose of combing out
straight the whole length of its fibre.

In order to give to the machine the necessary movements, a train of
toothed wheels and pinions is mounted, mostly on studs attached to the
side of the frame; which train of wheels and pinions is shown by dots in
the figure, to avoid confusion. The driving power, a horse or
steam-engine, is communicated by a band to a rigger on the short axle
_i_; which axle carries a pinion, taking into one of the wheels of the
train. From this wheel the crank _e_, that works the lever _d_, is
driven; and also, by geer from the same pinion, the axle of the wheel
_b_, carrying the eccentric or heart-wheel cam, is also actuated, but
slower than the crank-axle.

At the end of the axle of the wheel _b_, and cam _c_, a bevel pinion is
affixed, which geers into a corresponding bevel pinion on the end of the
lateral shaft _k_. The reverse end of this shaft has a worm or endless
screw _l_, taking into a toothed wheel _m_; and this last-mentioned
toothed wheel geers into a rack at the under part of the frame _g_.

It will hence be perceived, that by the movements of the train of
wheels, a slow motion is given to the frame _g_, by which the lower
needles carrying the wool are progressively advanced as the operation
goes on; and also, that by the other wheels of the train, the
heart-wheel cam is made to rotate, for the purpose of giving such
varying directions to the stroke of the lever which slides upon its
periphery, and to the working comb, as shall cause the comb to operate
gradually upon the wool as it is brought forward. The construction of
the frames which hold the needles, and the manner of fixing them in the
machine, present no features of importance; it is therefore unnecessary
to describe them farther, than to say, that the heckles are to be heated
when used for combing wool. Instead of introducing the wool to be combed
into the lower needles by hand, it is sometimes fed in, by means of an
endless feeding-cloth, as shown in _fig._ 1206. This endless cloth is
distended over two rollers, which are made to revolve, for the purpose
of carrying the cloth with the wool forward, by means of the endless
screw and pinions.

[Illustration: 1206 1207]

A slight variation in the machine is shown at _fig._ 1207., for the
purpose of combing wool of long fibre, which differs from the former
only in placing the combs or needle points upon a revolving cylinder or
shaft. At the end of the axle of this shaft, there is a toothed wheel,
which is actuated by an endless screw upon a lateral shaft. The axle of
the cylinder on which the needles are fixed, is mounted in a movable
frame or carriage, in order that the points of the needles may, in the
first instance, be brought to act upon the ends of the wool only, and
ultimately be so advanced as to enable the whole length of the fibres to
be drawn through. The progressive advancement of this carriage, with the
needle cylinder, is effected by the agency of the endless screw on the
lateral shaft before mentioned.

Some combing-machines reduce the wool into a continuous sliver, which is
ready for the drawing-frame; but the short slivers produced by the hand
combing, must be first joined together, by what is called _planking_.
These slivers are rolled up by the combers ten or twelve together, in
balls called tops, each of which weighs half a pound. At the
spinning-mill these are unrolled, and the slivers are laid on a long
plank or trough, with the ends lapping over, in order to splice the long
end of one sliver into the short end of another. The long end is that
which was drawn off first from the comb, and contains the longer fibres;
the short is that which comes last from the comb, and contains the
shorter. The wool-comber lays all the slivers of each ball the same way,
and marks the long end of each by twisting up the end of the sliver. It
is a curious circumstance, that when a top or ball of slivers is
unrolled and stretched out straight, they will not separate from each
other without tearing and breaking, if the separation is begun at the
short ends; but if they are first parted at the long ends, they will
readily separate.

The machine for combing long wool, for which Messrs. Donisthorpe and
Rawson obtained a patent in April, 1835, has been found to work well,
and therefore merits a detailed description:--

[Illustration: 1208 1209 1210]

_Fig._ 1208. is an elevation; _fig._ 1209. an end view; and _fig._ 1210.
a plan; in which _a_, _a_, is the framing; _b_, the main shaft, bearing
a pinion which drives the wheel and shaft _c_, in geer with the wheel
_d_, on the shaft _e_. Upon each of the wheels _c_ and _d_, there are
two projections or studs _f_, which cause the action of the combs _g_,
_g_, of which _h_, _h_, are the tables or carriages. These are capable
of sliding along the upper guide rails of the framing _a_. Through these
carriages or tables _h_, _h_, there are openings or slits, shown by
dotted lines, which act as guides to the holders _i_, _i_, of the combs
_g_, _g_, rendering the holders susceptible of motion at right angles to
the course pursued by the tables _h_. The combs are retained in the
holders _i_, _i_, by means of the lever handles _j_, _j_, which move
upon inclined surfaces, and are made to press on the surface of the
heads of the combs _g_, _g_, so as to be retained in their places; and
they are also held by studs affixed to the holders, which pass into the
comb-heads. From the under side of the tables, forked projections _i_,
_i_, stand out, which pass through the openings or slits formed in the
tables _h h_; these projections are worked from side to side by the
frame _k_, _k_, which turning on the axis or shaft _l_, _l_, is caused
to vibrate, or rock to and fro, by the arms _m_, moved by the eccentric
groove _n_, made fast to the shaft _e_. The tables _h_, are drawn
inwards, by weights suspended on cords or straps _o_, _o_, which pass
over friction pulleys _p_, _p_; whereby the weights have a constant
tendency to draw the combs into the centre of the machine, as soon as it
is released by the studs _f_, passing beyond the projecting arms _g_, on
the tables. On the shaft _c_, a driving-tooth or catch _r_, is fixed,
which takes into the ratchet wheel _s_, and propels one of its teeth at
every revolution of the shaft _c_. This ratchet wheel turns on an axis
at _t_; to the ratchet the pulley _v_ is made fast, to which the cord or
band _w_ is secured, as also to the pulley _x_, on the shaft _y_. On the
shaft _y_, there are two other pulleys _z_, _z_, having the cords or
bands A, A, made fast to them, and also to the end of the gauge-plates
B, furnished with graduated steps, against which the tables _h_, _h_,
are drawing at each operation of the machine. In proportion as these
gauge-plates are raised, the nearer the carriages or tables _h_, will be
able to advance to the centre of the machine, and thus permit the combs
_g_, _g_, to lay hold of, and comb, additional lengths of the woolly
fibres. The gauge-plates B, are guided up by the bars C, which pass
through openings, slots, or guides, made in the framing _a_, as shown by
D.

To the ratchet wheel _s_, an inclined projection E, is made fast, which
in the course of the rotation of the ratchet wheel, comes under the
lever F, fixed to the shaft G, that turns in bearings H. To this shaft
the levers I and J, are also fixed; I serving to throw out the click or
catch K, from the ratchet wheel, by which the parts of the machine will
be released, and restored to positions ready for starting again. The
lever J, serves to slide the drum upon the driving shaft _b_, out of
geer, by means of the forked handle L, when the machine is to be
stopped, whenever it has finished combing a certain quantity of wool.
The combs which hold the wool have a motion upwards, in order to take
the wool out of the way of the combs _g_, _g_, as these are drawn into
the centre of the machine; while the holding combs descend to lay the
wool among the points of the combs _g_, _g_. For obtaining this upward
and downward motion, the combs M, M, are placed upon the frame N, and
retained there just as the combs _g_, _g_, are upon the holders _i_,
_i_. The framing N is made fast to the bar or spindle O, which moves
vertically through openings in the cross-head P, and the cross-framing
of the machine Q; from the top of which, there is a strap passes over
pulleys with a weight suspended to it; the cross-head being supported by
the two guide-rods R, fixed to the cross-framing Q. It is by the
guide-rods R, and the spindle O, that the frame N is made to move up and
down; while the spindle is made to rise by the studs _f_, as the wheels
_c_ and _d_ come successively under the studs _s_, on the spindle O.

A quantity of wool is to be placed on each of the combs _g_, _g_, and M,
M, the machine being in the position shown in _fig._ 1210. When the main
shaft _b_, is set in motion, it will drive by its pinion the toothed
wheel _c_, and therefrom the remaining parts of the machine. The first
effect of the movement will be to raise the combs M, M, sufficiently
high to remove the wool out of the way of the combs _g_, _g_, which will
be drawn towards the centre of the machine, as soon as they are released
by the studs _f_, passing the projecting arms _q_, on the tables _h_;
but the distance between the combs _g_, _g_, and the combs H, H, will
depend on the height to which the gauge-plates B, have been raised.
These plates are raised one step at each revolution of the shaft _c_;
the combs _g_, _g_, will therefore be continually approaching more
nearly to the combs M, M, till the plates B, are so much raised as to
permit the tables _h_, to approach the plates B, below the lowest step
or graduation, when the machine will continue to work. Notwithstanding
the plates B, continuing to rise, there being only parallel surfaces
against which the tables come, the combs _g_, _g_, will successively
come to the same position, till the inclined projection E, on the
ratchet wheel _s_, comes under the lever F, which will stop the machine.
The wool which has been combed, is then to be removed, and a fresh
quantity introduced. It should be remarked, that the combs _g_, _g_, are
continually moving from side to side of the machine, at the same time
that they are combing out the wool. The chief object of the invention is
obviously to give the above peculiar motions to the combs _g_, _g_, and
M, M; which may be applied also to combing goat-hair.

For the purposes of the worsted manufacture, wool should be rendered
inelastic to a considerable degree, so that its fibres may form long
lines, capable of being twisted into straight level yarn. Mr. Bayliffe,
of Kendal, has sought to accomplish this object, first, by introducing
into the _drawing_ machine a rapidly revolving wheel, in contact with
the front drawing roller, by whose friction the filaments are heated,
and at the same time deprived of their curling elasticity; secondly, by
employing a movable regulating roller, by which the extent of surface on
the periphery of the wheel that the lengths of wool is to act upon, may
be increased or diminished at pleasure, and, consequently, the effect
regulated or tempered as the quality of the wool may require; thirdly,
the employment of steam in a rotatory drum, or hollow wheel, in place of
the wheel first described, for the purpose of heating the wool, in the
process of drawing, in order to facilitate the operation of
straightening the fibres.

[Illustration: 1211]

These objects may be effected in several ways; that is, the machinery
may be variously constructed, and still embrace the principles proposed.
_Fig._ 1211. shows one mode:--_a_, is the friction wheel; _b_, the front
drawing roller, placed in the drawing frame in the same way as usual;
the larger wheel _a_, constituting the lower roller of the pair of front
drawing rollers; _c_, and _d_, are the pair of back drawing rollers,
which are actuated by geer connected to the front rollers, as in the
ordinary construction of drawing machines, the front rollers moving very
considerably faster than the back rollers, and, consequently, drawing or
extending the fibres of the sliver of wool, as it passes through between
them; _e_, is a guide roller, bearing upon the periphery of the large
wheel; _f_, is a tension roller, which presses the fibres of the wool
down upon the wheel _a_.

Now, supposing the back rollers _c_ and _d_ to be turned with a given
velocity, and the front roller _b_ to be driven much faster, the effect
would be, that the fibres of wool constituting the sliver, passing
through the machine, would be considerably extended between _b_ and _d_,
which is precisely the effect accomplished in the ordinary drawing
frame; but the wheel _a_, introduced into the machine in place of the
lower front drawing roller, being made to revolve much faster than _b_,
the sliver of wool extended over the upper part of its periphery from
_b_, to the tension roller _f_, will be subjected to very considerable
friction from the contact; and, consequently, the natural curl of the
wool will be taken out, and its elasticity destroyed, which will enable
the wool to proceed in a connected roving down to the spindle or flyer
_h_, where it becomes twisted or spun into a worsted thread.

In order to increase or diminish the extent to which the fibres of wool
are spread over the periphery of the wheel _a_, a regulating roller is
adapted to the machine, as shown at _g_, in place of the tension roller
_f_. This regulating roller _g_, is mounted by its pivots in bearings on
the circular arms _h_, shown by dots. These circular arms turn loosely
upon the axle of the wheel _a_, and are raised or depressed by a rack
and a winch, not shown in the figure; the rack taking into teeth on the
periphery of the circular arms. It will hence be perceived, that by
raising the circular arms, the roller _g_, will be carried backward, and
the fibres of wool pressed upon the periphery of the wheel to a greater
extent. On the contrary, the depression of the circular arms will draw
the roller _g_, forward, and cause the wool to be acted upon by a
smaller portion of the periphery of the wheel _a_, and consequently
subject it to less friction.

When it is desired to employ steam for the purpose of heating the wool,
the wheel _a_, is formed as a hollow drum, and steam from a boiler, in
any convenient situation, is conveyed through the hollow axle to the
interior of the drum, which, becoming heated by that means, communicates
heat also to the wool, and thereby destroys its curl and elasticity.

[Illustration: 1212]

_Breaking-frame._--Here the slivers are _planked_, or spliced together,
the long end of one to the short end of another; after which they are
drawn out and extended by the rollers of the breaking-frame. A sketch of
this machine is given in _fig._ 1212. It consists of four pairs of
rollers A, B, C, D. The first pair A, receives the wool from the
inclined trough E, which is the planking-table. The slivers are
unrolled, parted, and hung loosely over a pin, in reach of the
attendant, who takes a sliver, and lays it flat in the trough, and the
end is presented to the rollers A, which being in motion, will draw the
wool in; the sliver is then conducted through the other rollers, as
shown in the figure: when the sliver has passed half through, the end of
another sliver is placed upon the middle of the first, and they pass
through together; when this second is passed half through, the end of a
third is applied upon the middle of it, and in this way the short
slivers produced by the combing are joined into one regular and even
sliver.

The lower roller C receives its motion from the mill, by means of a
pulley upon the end of its axis, and an endless strap. The roller which
is immediately over it, is borne down by a heavy weight, suspended from
hooks, which are over the pivots of the upper roller. The fourth pair of
rollers D, moves with the same velocity as C, being turned by means of
a small wheel upon the end of the axis of the roller C, which turns a
wheel of the same size upon the axis of the roller D, by means of an
intermediate wheel _d_, which makes both rollers turn the same way
round. The first and second pairs of rollers, A and B, move only
one-third as quick as C and D, in order to draw out the sliver between B
and C to three times the length it was when put on the planking-table.
The slow motion of the rollers A, is given by a large wheel _a_, fixed
upon the axis of the roller A, and turned by the intermediate cog-wheels
_b_, _c_, and _d_; the latter communicates between the rollers C and D.
The pinions on the rollers C and D being only one-third the size of the
wheel _a_, C and D turn three times as fast as A, for _b_, _c_, and _d_,
are only intermediate wheels. The rollers B turn at the same rate as A.
The upper roller C is loaded with a heavy weight, similar to the rollers
A; but the other rollers, B and D, are no further loaded than the weight
of the rollers.

The two pairs of rollers A, B, and C, D, are mounted in separate frames;
and that frame which contains the third and fourth pairs C, D, slides
upon the cast-iron frame F, which supports the machine, in order to
increase or diminish the distance between the rollers B and C. There is
a screw _f_, by which the frame of the rollers is moved, so as to adjust
the machine according to the length of the fibres of the wool. The space
between B and C should be rather more than the length of the fibres of
the wool. The intermediate wheels _b_ and _c_, are supported upon pieces
of iron, which are movable on centres; the centre for the piece which
supports the wheel _b_ is concentric with the axis of the roller A; and
the supporting piece for the wheel _c_ is fitted on the centre of the
wheel _d_. By moving these pieces the intermediate wheels _b_ and _c_
can be always kept in contact, although the distance between the rollers
is varied at times. By means of this breaking-frame, the perpetual
sliver, which is made up by planking the sliver together, is equalized,
and drawn out three times in length, and delivered into the can G.

_Drawing-frame._--Three of these cans are removed to the drawing-frame,
which is similar to the breaking-frame, except that there is no
planking-table E. There are five sets of rollers, all fixed upon one
common frame F, the breaking-frame, which we have described, being the
first. As fast as the sliver comes through one set of rollers, it is
received into a can, and then three of these cans are put together, and
passed again through another set of rollers. In the whole, the wool must
pass through the breaker and four drawing-frames before the roving is
begun. The draught being usually four times at each operation of
drawing, and three times in the breaking, the whole will be 3 + 4 + 4 +
4 + 4 = 768; but to suit different sorts of wool, the three last
drawing-frames are capable of making a greater draught, even to five
times, by changing the pinions; accordingly the draught will be 3 + 4 +
5 + 5 + 5 = 1500 times.

The size of the sliver is diminished by these repeated drawings, because
only three slivers are put together, and they are drawn out four times;
so that, in the whole, the sliver is reduced to a fourth or a ninth of
its original bulk.

The breaking-frame and drawing-frame which are used when the slivers are
prepared by the combing-machines, are differently constructed; they have
no planking-table, but receive three of the perpetual slivers of the
combing-machine from as many tin cans, and draw them out from ten to
twelve times. In this case, all the four rollers contribute to the
operation of drawing: thus the second rollers B, move 2-1/2 times as
fast as the rollers A; the third rollers C, move 8 times as fast as A;
and the fourth rollers E, move 10-1/2 times as fast as A. In this case,
the motion is given to the different rollers by means of bevelled
wheels, and a horizontal axis, which extends across the ends of all the
four rollers, to communicate motion from one pair of rollers to another.

There are three of these systems of rollers, which are all mounted on
the same frame; and the first one through which the wool passes, is
called the breaking-frame; but it does not differ from the others,
which are called drawing-frames. The slivers which have passed through
one system of rollers, are collected four or five together, and put
through the drawing-rollers. In all, the slivers pass through three
drawings, and the whole extension is seldom less than 1000 times, and
for some kinds of wool much greater.

After the drawing of the slivers is finished, a pound weight is taken,
and is measured by means of a cylinder, in order to ascertain if the
drawing has been properly conducted; if the sliver does not prove of the
length proposed, according to the size of worsted which is intended to
be spun, the pinions of some of the drawing-frames are changed, to make
the draught more or less, until it is found by experiment that one pound
of the sliver measures the required length.

_Roving-frame._--This is provided with rollers, the same as the
drawing-frames: it takes in one or two slivers together, and draws them
out four times. By this extension, the sliver becomes so small, that it
would break with the slightest force, and it is therefore necessary to
give some twist; this is done by a spindle and flyer. See _Roving_,
under COTTON MANUFACTURE.

_Spinning-frame._--This is so much like the roving-frame, that a short
description will be sufficient. The spindles are more delicate, and
there are three pairs of rollers, instead of two; the bobbins, which are
taken off from the spindles of the roving-frame, when they are quite
full, are stuck upon skewers, and the roving which proceeds from them is
conducted between the rollers. The back pair turns round slowly; the
middle pair turns about twice for once of the back rollers; and the
front pair makes from twelve to seventeen turns for one turn of the back
roller, according to the degree of extension which is required.

The spindles must revolve very quickly in the spinning-frame, in order
to give the requisite degree of twist to the worsted. The hardest
twisted worsted is called tammy warp; and when the size of this worsted
is such as to be 20 or 24 hanks to the pound weight, the twist is about
10 turns in each inch of length. The least twist is given to the worsted
for fine hosiery, which is from 18 to 24 hanks to the pound. The twist
is from 5 to 6 turns per inch. The degree of twist is regulated by the
size of the whirls or pulleys upon the spindle, and by the wheel-work
which communicates the motion to the front rollers from the band-wheel,
which turns the spindles.

It is needless to enter more minutely into the description of the
spinning machinery, because the fluted roller construction, invented by
Sir Richard Arkwright, fully described under COTTON MANUFACTURE, is
equally applicable to worsted. The difference between the two, is
chiefly in the distance between the rollers, which, in the
worsted-frame, is capable of being increased or diminished at pleasure,
according to the length of the fibres of the wool; and the draught or
extension of the roving is far greater than in the cotton.

_Reeling._--The bobbins of the spinning-frame are placed in a row upon
wires before a long horizontal reel, and the threads from 20 bobbins are
wound off together. The reel is exactly a yard in circumference, and
when it has wound off 80 turns, it rings a bell; the motion of the reel
is then stopped, and a thread is passed round the 80 turns or folds
which each thread has made. The reeling is then continued till another
80 yards is wound off, which is also separated by interweaving the same
thread; each of these separate parcels is called a ley, and when 7 such
leys are reeled, it is called a hank, which contains 560 yards. When
this quantity is reeled off, the ends of the binding thread are tied
together, to bind each hank fast, and one of the rails of the reel is
struck to loosen the hanks, and they are drawn off at the end of the
reel. These hanks are next hung upon a hook, and twisted up hard by a
stick; then doubled, and the two parts twisted together to make a firm
bundle. In this state, the hanks are weighed by a small index-machine,
which denotes what number of the hanks will weigh a pound, and they are
sorted accordingly into different parcels. It is by this means that the
number of the worsted is ascertained as the denomination for its
fineness: thus No. 24. means, that 24 hanks, each containing 560 yards,
will weigh a pound, and so on.

This denomination is different from that used for cotton, because the
hank of cotton contains 840 yards, instead of 560; but in some places
the worsted hank is made of the same length as the cotton.

To pack up the worsted for market, the proper number of hanks is
collected to make a pound, according to the number which has been
ascertained; these are weighed as a proof of the correctness of the
sorting, then tied up in bundles of one pound each, and four of these
bundles are again tied together. Then 60 such bundles are packed up in a
sheet, making a bale of 240 pounds, ready for market.

_Of the treatment of short wool for the cloth manufacture._--Short wool
resembles cotton, not a little in the structure of its filaments, and is
cleaned by the _willy_, as cotton is by the _willow_, which opens up the
matted fleece of the wool-stapler, and cleans it from accidental
impurities. Sheep’s wool for working into coarse goods, must be passed
repeatedly through this machine, both before and after it is dyed; the
second last time for the purpose of blending the different sorts
together, and the last for imbuing the fibres intimately with oil. The
oiled wool is next subjected to a first carding operation called
_scribbling_, whereby it is converted into a broad thin fleece or lap,
as cotton is by the breaker-cards of a cotton mill. The woollen lap is
then worked by the cards proper, which deliver it in a narrow band or
sliver. By this process the wool expands greatly in all its dimensions;
while the broken or short filaments get entangled by crossing in every
possible direction, which prepares them for the fulling operation. See
_Carding_, under COTTON MANUFACTURE.

[Illustration: 1213]

The _slubbing machine_, or _billy_, reduces the separate rolls of
_cardings_ into a continuous slightly twisted spongy cord, which is
sometimes called a roving. _Fig._ 1213. is a perspective representation
of the slubbing machine in most common use. A, A, is the wooden frame;
within which is the movable carriage D, D, which runs upon the lower
side rails at _a_, _a_, on friction wheels at 1, 2, to make it move
easily backwards and forwards from one end of the frame to the other.
The carriage contains a series of steel spindles, marked 3, 3, which
receive rapid rotation from a long tin drum F, by means of a series of
cords passing round the pulley or whorl of each spindle. This drum, 6
inches in diameter, is covered with paper, and extends across the whole
breadth of the carriage. The spindles are set nearly upright in a frame,
and about 4 inches apart; their under ends being pointed conically, turn
in brass sockets called steps, and are retained in their position by a
small brass collet, which embraces each spindle at about the middle of
its length. The upper half of each spindle projects above the top of the
frame. The drum revolves horizontally before the spindles, having its
axis a little below the line of the whorls; and receives motion, by a
pulley at one of its ends, from an endless band which passes round a
wheel E, like the large domestic wheel formerly used in spinning wool by
hand, and of similar dimensions. This wheel is placed upon the outside
of the main frame of the machine, and has its shafts supported by
upright standards upon the carriage D. It is turned by the spinner
placed at Q, with his right hand applied to a winch R, which gives
motion to the drum, and thereby causes the spindles to revolve with
great velocity.

Each spindle receives a soft cylinder or carding of wool, which comes
through beneath a wooden roller C, C, at the one end of the frame. This
is the _billy roller_, so much talked of in the controversies between
the operatives and masters in the cotton factories, as an instrument of
cruel punishment to children, though no such machine has been used in
cotton mills for half a century at least. These woollen rolls proceed to
the series of spindles, standing in the carriage, in nearly a horizontal
plane. By the alternate advance and retreat of the carriage upon its
railway, the spindles are made to approach to, and recede from, the
roller C, with the effect of drawing out a given length of the soft
cord, with any desired degree of twist, in the following manner:--

The carding rolls are laid down straight, side by side, upon the endless
cloth, strained in an inclined direction between two rollers, one of
which is seen at B, and the other lies behind C. One carding is
allotted to a spindle; the total number of each in one machine being
from 50 to 100. The roller C, of light wood, presses gently with its
weight upon the cardings, while they move onwards over the endless
cloth, with the running out of the spindle carriage. Immediately in
front of the said roller, there is a horizontal wooden rail or bar G,
with another beneath it, placed across the frame. The carding is
conducted through between these two bars, the movable upper one being
raised to let any aliquot portion of the roll pass freely. When this bar
is again let down, it pinches the spongy carding fast; whence this
mechanism is called the clasp. It is in fact the _clove_, originally
used by Hargreaves in his cotton-jenny. The movable upper rail G, is
guided between sliders, and a wire 7, descends from it to a lever C.
When the spindle carriage D, D, is wheeled close home to the billy
roller, a wheel 5, lifts the end 6 of the lever, which, by the wire 7,
raises the upper bar or rail G, so as to open the clasp, and release all
the card rolls. Should the carriage be now drawn a little way from the
clasp bars, it would tend to pull a corresponding length of the cardings
forward from the inclined plane B, C. There is a small catch, which lays
hold of the upper bar of the clasp G, and hinders it from falling till
the carriage has receded to a certain distance, and has thereby allowed
from 7 to 8 inches of the cardings to be taken out. A stop upon the
carriage then comes against the catch, and withdraws it; thus allowing
the upper rail to fall and pinch the carding, while the carriage,
continuing to recede, draws out or stretches that portion of the roll
which is between the clasp and the spindle points. But during this time
the wheel has been turned to keep the spindles revolving, communicating
the proper degree of twist to the cardings in proportion to their
extension, so as to prevent them from breaking.

It might be imagined that the slubbing cords would be apt to coil round
the spindles; but as they proceed in a somewhat inclined direction to
the clasp, they receive merely a twisting motion, continually slipping
over the points of the spindles, without getting wound upon them.
Whenever the operative or slubber has given a due degree of twist to the
rovings, he sets about winding them upon the spindles into a conical
shape, for which purpose he presses down the faller-wire 8, with his
left hand, so as to bear it down from the points of the spindles, and
place it opposite to their middle part. He next makes the spindles
revolve, while he pushes in the carriage slowly, so as to coil the
slubbing upon the spindle into a conical cop. The wire 8, regulates the
winding-on of the whole series of slubbings at once, and receives its
proper angle of depression for this purpose from the horizontal rail 4,
which turns upon pivots in its ends, in brasses fixed on the standards,
which rise from the carriage D. By turning this rail on its pivots, the
wire 8 may be raised or lowered in any degree. The slubber seizes the
rail 4 in his left hand, to draw the carriage out; but in returning it,
he depresses the faller-wire, at the same time that he pushes the
carriage before him.

The cardings are so exceedingly tender, that they would readily draw
out, or even break, if they were dragged with friction upon the endless
cloth of the inclined plane. To save this injurious traction, a
contrivance is introduced for moving the apron. A cord is applied round
the groove in the middle part of the upper roller, and after passing
over pulleys, as shown in the figure, it has a heavy weight hung at the
one end, and a light weight at the other, to keep it constantly
extended, while the heavy weight tends to turn the rollers with their
endless cloth round in such a direction as to bring forward the rovings,
without putting any strain upon them. Every time that the carriage is
pushed home, the larger weight gets wound up; and when the carriage is
drawn out, the greater weight turns the roller, and advances the endless
apron, so as to deliver the carding at the same rate as the carriage
runs out; but when the proper quantity is delivered, a knot in the rope
arrives at a fixed stop, which does not permit it to move any further;
while at the same instant the roller 5 quits the lever 6, and allows the
upper rail G, of the clasp to fall, and pinch the carding fast; the
wheel E, being then set in motion, makes the spindles revolve; and the
carriage being simultaneously drawn out, extends the slubbings while
under the influence of twisting. In winding up the slubbings, the
operative must take care to push in the carriage, and to turn the wheel
round at such rates that the spindles will not take up faster than the
carriage moves on its railway, or he would injure the slubbings. The
machine requires the attendance of a child, to bring the cardings from
the card-engine, to place them upon the sloping feed-cloth, and to join
the ends of the fresh ones carefully to the ends of the others newly
drawn under the roller. Slubbings intended for warp-yarn must be more
twisted than those for weft; but each must receive a degree of torsion
relative to the quality of the wool and of the cloth intended to be
made. In general, however, no more twist should be given to the
slubbings than is indispensable for enabling them to be drawn out to the
requisite slenderness without breaking. This twist forms no part of the
twist of the finished yarn, for the slubbing will be twisted in the
contrary direction, when spun afterwards in the jenny or mule.

I may here remark, that various machines have been constructed of late
years for making continuous card-ends, and slubbings, in imitation of
the carding and roving of the COTTON MANUFACTURE; to which article I
therefore refer my readers. The wool slubbings are now spun into yarn,
in many factories, by means of the mule. Indeed, I have seen in France
the finest yarn, for the _mousseline-de-laine_ fabrics, beautifully spun
upon the self-actor mule of Sharp and Roberts.[72]

  [72] See this admirable machine fully described and delineated in my
  _Cotton Manufacture of Great Britain_, vol. ii.

_Tentering._--When the cloth is returned from the fulling-mill (which
see), it is stretched upon the tenter-frame, and left in the open air
till dry.

In the woollen manufacture, as the cloth suffers, by the operation of
the fulling-mill, a shrinkage of its breadth to well nigh one-half, it
must at first be woven of nearly double its intended width when
finished. Superfine six-quarter broad cloths must therefore be turned
out of the loom twelve-quarters wide.

_Burling_ is the name of a process, in which the dried cloth is examined
minutely in every part, freed from knots or uneven threads, and repaired
by sewing any little rents, or inserting sound yarns in the place of
defective ones.

_Teasling._--The object of this operation is to raise up the loose
filaments of the woollen yarn into a nap upon one of the surfaces of the
cloth, by scratching it either with thistle-heads, called teasels, or
with teasling-cards or brushes, made of wire. The natural teasels are
the balls which contain the seeds of the plant called _Dipsacus
fullorum_; the scales which form the balls, project on all sides, and
end in sharp elastic points, that turn downwards like hooks. In teasling
by hand, a number of these balls are put into a small wooden frame,
having crossed handles, eight or ten inches long; and when thus filled,
form an implement not unlike a curry-comb, which is used by two men, who
seize the teasel-frame by the handles, and scrub the face of the cloth,
hung in a vertical position from two horizontal rails, made fast to the
ceiling of the workshop. First, they wet the cloth, and work three times
over, by strokes in the direction of the warp, and next of that of the
weft, so as to raise all the loose fibres from the felt, and to prepare
it for shearing. In large manufactories, this dressing operation is
performed by a machine called a gig-mill, which originally consisted,
and in most places still consists, of a cylinder bristled all over with
the thistle-heads, and made to revolve rapidly while the cloth is drawn
over it in a variety of directions. If the thistle be drawn in the line
of the warp, the points act more efficaciously upon the weft, being
perpendicular to its softer spun yarns. Inventors who have tried to give
the points a circular or oblique action between the warp and the weft,
proceed apparently upon a false principle, as if the cloth were like a
plate of metal, whose substance could be pushed in any direction.
Teasling really consists in drawing out one end of the filaments, and
leaving the body of them entangled in the cloth; and it should seize and
pull them perpendicularly to their length, because in this way it acts
upon the ends, which being least implicated, may be most readily
disengaged.

When the hooks of the thistles become clogged with flocks of wool, they
must be taken out of the frame or cylinder, and cleaned by children with
a small comb. Moisture, moreover, softens their points, and impairs
their teasling powers; an effect which needs to be counterbalanced, by
taking them out, and drying them from time to time. Many contrivances
have, therefore, been proposed, in which metallic teasels of an
unchangeable nature, mounted in rotatory machines, driven by power, have
been substituted for the vegetable, which being required in prodigious
quantities, become sometimes excessively scarce and dear in the clothing
districts. In 1818, several schemes of that kind were patented in
France, of which those of M. Arnold-Merick, and of MM. Taurin frères, of
Elbœuf, are described in the 16th volume of _Brevets d’Invention
expirés_. Mr. Daniell, cloth manufacturer in Wilts, renewed this
invention under another form, by making his rotatory cards with two
kinds of metallic wires, of unequal lengths; the one set, long, thin,
and delicate, representing the points of the thistle; the other,
shorter, stiffer, and blunter, being intended to stay the cloth, and to
hinder the former from entering too far into it. But none of these
processes have succeeded in discarding the natural teasel from the most
eminent manufactories.

The French government purchased, in 1807, the patent of Douglas, an
English mechanist, who had, in 1802, imported into France, the best
system of gig-mills then used in the west of England. A working set of
his machines having been placed in the _Conservatoire des Arts_, for
public inspection, they were soon introduced into most of the French
establishments, so as generally to supersede teasling (_lainage_) by
hand. A description of them was published in the third volume of the
_Brevets d’Invention_. The following is an outline of some subsequent
improvements:--

1. As it was imagined that the seesaw action of the hand operative was
in some respects more effectual than the uniform rotation of a gig-mill,
this was attempted to be imitated by an alternating movement.

2. Others conceived that the seesaw motion was not essential, but that
it was advantageous to make the teasels or cards act in a rectilinear
direction, as in working by hand; this action was attempted by placing
the two ends of the teasel-frame in grooves formed like the letter D, so
that the teasel should act on the cloth only when it came into the
rectilinear part. Mr. Wells, machine-maker, of Manchester, obtained a
patent, in 1832, for this construction.

3. It was supposed that the teasels should not act perpendicularly to
the weft, but obliquely or circularly upon the face of the cloth. Mr.
Ferrabee, of Gloucester, patented, in 1830, a scheme of this kind, in
which the teasels are mounted upon two endless chains, which traverse
from the middle of the web to the selvage or list, one to the right, and
another to the left hand, while the cloth itself passes under them with
such a velocity, that the effect, or _resultant_, is a diagonal action,
dividing into two equal parts the rectangle formed by the weft and warp
yarns. Three patent machines of Mr. George Oldland--the first in 1830,
the second and third in 1832--all proceed upon this principle. In the
first, the teasels are mounted upon discs made to turn flat upon the
surface of the cloth; in the second, the rotating discs are pressed by
corkscrew spiral springs against the cloth, which is supported by an
elastic cushion, also pressed against the discs by springs; and in the
third machine, the revolving discs have a larger diameter, and they
turn, not in a horizontal, but a vertical plane.

4. Others fancied that it would be beneficial to support the reverse
side of the cloth by flat hard surfaces, while acting upon its face with
cards or teasels. Mr. Joseph Cliseld Daniell, having stretched the cloth
upon smooth level stones, teasels them by hand. 5. Messrs. Charlesworth
and Mellor obtained a patent, in 1829, for supporting the back of the
cloth with elastic surfaces, while the part was exposed to the teasling
action. 6. Elasticity has also been imparted to the teasels, in the
three patent inventions of Mr. Sevill, Mr. J. C. Daniell, and Mr. R.
Atkinson. 7. It has been thought useful to separate the teasel-frames
upon the drum of the gig-mill, by simple rollers, or by rollers heated
with steam, in order to obtain the combined effect of calendering and
teasling. Mr. J. C. Daniell, Mr. G. Haden, and Mr. J. Rayner, have
obtained patents for contrivances of this kind. 8. Several French
schemes have been mounted for making the gig-drum act upon the two sides
of the cloth, or even to mount two drums on the same machine.

Mr. Jones, of Leeds, contrived a very excellent method of stretching the
cloth, so as to prevent the formation of folds or wrinkles. (See
Newton’s Journal, vol. viii., 2nd series, page 126.) Mr. Collier, of
Paris, obtained a patent, in 1830, for a greatly improved gig-mill, upon
Douglas’s plan, which is now much esteemed by the French clothiers. The
following figures and description exhibit one of the latest and best
teasling machines. It is the invention of M. Dubois and Co., of
Louviers, and is now doing excellent work in that celebrated seat of the
cloth manufacture.

In the fulling-mill, the woollen web acquires body and thickness, at the
expense of its other dimensions; for being thereby reduced about
one-third in length, and one-half in breadth, its surface is diminished
to one-third of its size as it comes out of the loom; and it has, of
course, increased threefold in thickness. As the filaments drawn forth
by teasling, are of very unequal lengths, they must be shorn to make
them level, and with different degrees of closeness, according to the
quality of the stuff, and the appearance it is desired to have. But, in
general, a single operation of each kind is insufficient; whence, after
having passed the cloth once through the gig-mill, and once through the
shearing-machine (_tondeuse_), it is ready to receive a second teasling,
deeper than the first, and then to suffer a second shearing. Thus, by
the alternate repetition of these processes, as often as is deemed
proper, the cloth finally acquires its wished-for appearance. Both of
these operations are very delicate, especially the first; and if they be
ill conducted, the cloth is weakened, so as to tear or wear most
readily. On the other hand, if they be skilfully executed, the fabric
becomes not only more sightly, but it acquires strength and durability,
because its face is changed into a species of fur, which protects it
from friction and humidity.

[Illustration: 1214 1215]

_Figs._ 1214, 1215., represent the gig-mill in section, and in front
elevation. A, B, C, D, A´, B´, C´, D´, being the strong frame of iron,
cast in one piece, having its feet enlarged a little more to the inside
than to the outside, and bolted to large blocks in the stone pavement.
The two uprights are bound together below by two cross-beams A´´, being
fastened with screw-bolts at the ears _a´´_, _a´´_; and at top, by the
wrought-iron stretcher-rod D, whose ends are secured by screw-nuts at D,
D´. The drum is mounted upon a wrought-iron shaft F, which bears at its
right end (_fig._ 1215.), exterior to the frame, the usual riggers, or
fast and loose pulley, _ff´´_, _f´_, which give motion to the machine by
a band from the main shaft of the mill. On its right end, within the
frame, the shaft F, has a bevel wheel F´, for transmitting movement to
the cloth, as shall be afterwards explained. Three crown wheels G, of
which one is shown in the section, _fig._ 1214., are, as usual, keyed by
a wedge to the shaft F. Their contour is a sinuous band, with six
semi-cylindrical hollows, separated alternately by as many portions of
the periphery. One of these three wheels is placed in the middle of the
shaft F, and the other two, towards its extremities. Their size may be
judged of, from inspection of _fig._ 1214. After having set them so that
all their spokes or radii correspond exactly, the 16 sides H, are made
fast to the 16 portions of the periphery, which correspond in the three
wheels. These sides are made of sheet iron, curved into a gutter form,
_fig._ 1214., but rounded off at the end, _fig._ 1215., and each of them
is fixed to the three felloes of the wheels by three bolts _h_. The
elastic part of the plate iron allows of their being sufficiently well
adjusted, so that their flat portions furthest from the centre may lie
pretty truly on a cylindrical surface, whose axis would coincide with
that of the shaft F.

[Illustration: 1216 1217 1218]

Between the 16 sides there are 16 intervals, which correspond to the 16
hollowings of each of the wheels. Into these intervals are adjusted,
with proper precautions, 16 frames bearing the teasels which are to act
upon the cloth. These are fitted in as follows:--Each has the shape of a
rectangle, of a length equal to that of the drum, but their breadth only
large enough to contain two thistle-heads set end to end, thus making
two rows of parallel teasels throughout the entire length, (see the
contour in _fig._ 1214.) A portion of the frame is represented in _fig._
1216. The large side I, against which the tops of the teasels rest, is
hollowed out into a semi-cylinder, and its opposite side is cleft
throughout its whole length, to receive the tails of the teasels, which
are seated and compressed in it. There are, moreover, cross-bars _i_,
which serve to maintain the sides of the frame I, at an invariable
distance, and to form short compartments for keeping the thistles
compact. The ends are fortified by stronger bars _k_, _k_, with
projecting bolts to fasten the frames between the ribs. The distance of
the sides of the frame I, I´, ought to be such, that if a frame be laid
upon the drum, in the interval of two ribs, the side I will rest upon
the inclined plane of one of the ribs, and the side I´ upon the inclined
plane of the other, (see _fig._ 1214.); while at the same time the bars
_k_, of the two ends of the frame, rest upon the flat parts of the ribs
themselves. This point being secured, it is obvious, that if the ends of
the bars _k_ be stopped, the frame will be made fast. But they need not
be fixed in a permanent manner, because they must be frequently removed
and replaced. They are fastened by the clamp, (_figs._ 1217, 1218.),
which is shut at the one end, and furnished at the other with a spring,
which can be opened or shut at pleasure. 2 and 4, in _fig._ 1215. (near
the right end of the shaft F), shows the place of the clamp, _figs._
1217, 1218. The bar of the right hand is first set in the clamp, by
holding up its other end; the frame is then let down into the left-hand
clamp.

The cloth is wound upon the lower beam Q, _fig._ 1214.; thence it passes
in contact with a wooden cylinder T, turning upon an axis, and proceeds
to the upper beam P, on to which it is wound: by a contrary movement,
the cloth returns from the beam P to Q, over the cylinder T; and may
thus go from the one to the other as many times as shall be requisite.
In these successive circuits it is presented to the action of the
teasels, under certain conditions. In order to be properly teasled, it
must have an equal tension throughout its whole breadth during its
traverse; it must be brought into more or less close contact with the
drum, according to the nature of the cloth, and the stage of the
operations; sometimes being a tangent to the surface, and sometimes
embracing a greater or smaller portion of its contour, it must travel
with a determinate speed, dependent upon the velocity of the drum, and
calculated so as to produce the best result: the machine itself must
make the stuff pass alternately from one winding beam to the other.

In _fig._ 1215., before the front end of the machine, there is a
vertical shaft L, as high as the framework, which revolves with great
facility, in the bottom step _l_, the middle collet _l´_, and top collet
_l´´_, in the prolongation of the stretcher D. Upon this upright shaft
are mounted--1. a bevel wheel L´; 2. an upper bevel pinion M, with its
boss M´; 3. a lower bevel pinion N, with its boss N´. The bevel wheel L´
is keyed upon the shaft L, and communicates to it the movement of
rotation which it receives from the pinion _f_, with which it is in
geer; but the pinion _f_, which is mounted upon the shaft F of the drum,
participates in the rotation which this shaft receives from the prime
mover, by means of the fast rigger-pulley _f´_. The upper pinion M is
independent upon the shaft L; that is to say, it may be slidden along
it, up and down, without being driven by it; but it may be turned in an
indirect manner by means of six curved teeth, projecting from its
bottom, and which may be rendered active or not, at pleasure; these
curved teeth, and their intervals, correspond to similar teeth and
intervals upon the top of the boss M´, which is dependent, by feathered
indentations, upon the rotation of L, though it can slide freely up and
down upon it. When it is raised, therefore, it comes into geer with M.
The pinion N, and its boss, have a similar mode of being thrown into and
out of geer with each other. The bosses M´ and N´, ought always to be
moved simultaneously, in order to throw one of them into geer, and the
other out of geer. The shaft L serves to put the cloth in motion, by
means of the bevel wheels P´´ and Q´´, upon the ends of the beams P, Q,
which take into the pinions M and N.

The mechanism destined to stretch the cloth is placed at the other end
of the machine, where the shafts of the beams P, Q, are prolonged beyond
the frame, and bear at their extremities P´ and Q´, armed each with a
brake. The beam P (_fig._ 1214.), turns in an opposite direction to the
drum; consequently the cloth is wound upon P, and unwound from Q. If, at
the same time as this is going on, the handle R´, of the brake-shaft, be
turned so as to clasp the brake of the pulley Q´, and release that of
the pulley P´, it is obvious that a greater or smaller resistance will
be occasioned in the beam Q, and the cloth which pulls it in unwinding,
will be able to make it turn only when it has acquired the requisite
tension; hence it will be necessary, in order to increase or diminish
the tension, to turn the handle R´ a little more or a little less in the
direction which clasps the brake of the pulley Q´; and as the brake acts
in a very equable manner, a very equable tension will take place all the
time that the cloth takes to pass. Besides, should the diminution of the
diameter of the beam Q, render the tension less efficacious in any
considerable degree, the brake would need to be unclamped a very little,
to restore the primitive tension.

When the cloth is to be returned from the beam P, to the beam Q, Z must
be lowered, to put the shaft L out of geer above, and in geer below;
then the cloth-beam Q, being driven by that vertical shaft, it will turn
in the same direction as the drum, and will wind the cloth round its
surface. In order that it may do so, with a suitable tension, the pulley
Q´ must be left free, by clasping the brake of the pulley P´, so as to
oppose an adequate resistance.

The cloth is brought into more or less close contact with the drum as
follows:--There is for this purpose a wooden roller T, against which it
presses in passing from the one winding beam to the other, and which may
have its position changed relatively to the drum. It is obvious, for
example, that in departing from the position represented in _fig._
1214., where the cloth is nearly a tangent to the drum, if the roller T´
be raised, the cloth will cease to touch it; and if it be lowered, the
cloth will, on the contrary, embrace the drum over a greater or less
portion of its periphery. For it to produce these effects, the roller is
borne at each end, by iron gudgeons, upon the heads of an arched rack
T´´ (_fig._ 1214.), where it is held merely by pins. These racks have
the same curvature as the circle of the frame, against which they are
adjusted by two bolts; and by means of slits, which these bolts
traverse, they may be slidden upwards or downwards, and consequently
raise or depress the roller T. But to graduate the movements, and to
render them equal in the two racks, there is a shaft U, supported by the
uprights of the frame, and which carries, at each end, pinions U´, U´´,
which work into the two racks T´, T´´: this shaft is extended in front
of the frame, upon the side of the head of the machine (_fig._ 1215.),
and there it carries a ratchet wheel _u_, and a handle _u´_. The
workman, therefore, requires merely to lay hold of the handle, and turn
it in the direction of the ratchet wheel, to raise the racks, and the
roller T, which they carry; or to lift the click or catch, and turn the
handle in the opposite direction, when he wishes to lower the roller, so
as to apply the cloth to a larger portion of the drum.

CLOTH CROPPING.

Of machines for cropping or shearing woollen cloths, those of Lewis and
Davis have been very generally used.

_Fig._ 1219. is an end view, and _fig._ 1220. is a side view, of Lewis’s
machine, for shearing cloth from list to list. _Fig._ 1221. is an end
view of the carriage, with the rotatory cutter detached from the frame
of the machine, and upon a larger scale: _a_, is a cylinder of metal, on
which is fixed a triangular steel wire; this wire is previously bent
round the cylinder in the form of a screw, as represented at _a_, _a_,
in _fig._ 1219., and, being hardened, is intended to constitute one edge
of the shear or cutter.

[Illustration: 1219 1220 1221 1222 1223]

The axis of the cylindrical cutter _a_, turns in the frame _b_, which,
having proper adjustments, is mounted upon pivots _c_, in the standard
of the travelling carriage _d_, _d_; and _e_, is the fixed or ledger
blade, attached to a bar _f_, which constitutes the other edge of the
cutter; that is, the stationary blade, against which the edges of the
rotatory cutter act; _f_ and _g_, are flat springs, intended to keep the
cloth (shown by dots) up against the cutting edges. The form of these
flat springs _f_, _g_, is shown at _figs._ 1222. and 1223., as
consisting of plates of thin metal cut into narrow slips (_fig._ 1222.),
or perforated with long holes, (_fig._ 1223.) Their object is to support
the cloth, which is intended to pass between them, and operate as a
spring bed, bearing the surface of the cloth against the cutters, so
that its pile or nap may be cropped off or shorn as the carriage _d_ is
drawn along the top rails of the standard or frame of the machine _h_,
_h_, by means of cords.

The piece of cloth to be shorn, is wound upon the beam _k_, and its end
is then conducted through the machine, between the flat springs _f_ and
_g_ (as shown in _fig._ 1221.), to the other beam _l_, and is then made
fast; the sides or lists of the cloth being held and stretched by small
hooks, called habiting hooks. The cloth being thus placed in the
machine, and drawn tight, is held distended by means of ratchets on the
ends of the beams _k_ and _l_, and palls. In commencing the operation of
shearing, the carriage _d_, must be brought back, as in _fig._ 1221., so
that the cutters shall be close to the list; the frame of the cutters is
raised up on its pivots as it recedes, in order to keep the cloth from
injury, but is lowered again previously to being put in action. A band
or winch is applied to the rigger or pulley _m_, which, by means of an
endless cord passed round the pulley _n_, at the reverse end of the axle
of _m_, and round the other pulleys _o_ and _p_, and the small pulley
_q_, on the axle of the cylindrical cutter, gives the cylindrical cutter
a very rapid rotatory motion; at the same time a worm, or endless screw,
on the axle of _m_ and _n_, taking into the teeth of the large wheel
_r_, causes that wheel to revolve, and a small drum _s_, upon its axle,
to coil up the cord, by which the carriage _d_, with the cutters _a_ and
_e_, and the spring bed _f_ and _g_, are slowly, but progressively, made
to advance, and to carry the cutters over the face of the cloth, from
list to list; the rapid rotation of the cutting cylinder _a_, producing
the operation of cropping or shearing the pile.

Upon the cutting cylinder, between the spiral blades, it is proposed to
place stripes of plush, to answer the purpose of brushes, to raise the
nap or pile as the cylinder goes around, and thereby assist in bringing
the points of the wool up to the cutters.

The same contrivance is adapted to a machine for shearing the cloth
lengthwise.

[Illustration: 1224 1225]

_Fig._ 1224. is a geometrical elevation of one side of Mr. Davis’s
machine. _Fig._ 1225. a plan or horizontal representation of the same,
as seen in the top; and _fig._ 1226. a section taken vertically across
the machine near the middle, for the purpose of displaying the working
parts more perfectly than in the two preceding figures. These three
figures represent a complete machine in working condition, the cutters
being worked by a rotatory motion, and the cloth so placed in the
carriage as to be cut from list to list. _a_, _a_, _a_, is a frame or
standard, of wood or iron, firmly bolted together by cross braces at the
ends and in the middle. In the upper side-rails of the standard, there
is a series of axles carrying anti-friction wheels _b_, _b_, _b_, upon
which the side-rails _c_, _c_, of the carriage or frame that bears the
cloth runs, when it is passing under the cutters in the operation of
shearing. The side-rails _c_, _c_, are straight bars of iron, formed
with edges _v_, on their under sides, which run smoothly in the grooves
of the rollers _b_, _b_, _b_. These side-rails are firmly held together
by the end stretchers _d_, _d_. The sliding frame has attached to it the
two lower rollers _e_, _e_, upon which the cloth intended to be shorn is
wound; the two upper lateral rollers _f_, _f_, over which the cloth is
conducted and held up; and the two end rollers _g_, _g_, by which the
habiting rails _h_, _h_, are drawn tight.

In preparing to shear a piece of cloth, the whole length of the piece
is, in the first place, tightly rolled upon one of the lower rollers
_e_, which must be something longer than the breadth of the cloth from
list to list. The end of the piece is then raised, and passed over the
top of the lateral rollers _f_, _f_, whence it is carried down to the
other roller _e_, and its end or farral is made fast to that roller. The
hooks of the habiting rails _h_, _h_, are then put into the lists, and
the two lower rollers _e_, _e_, with the two end rollers _g_, _g_, are
then turned, for the purpose of drawing up the cloth, and straining it
tight, which tension is preserved by ratchet wheels attached to the ends
of the respective rollers, with palls dropping into their teeth. The
frame carrying the cloth, is now slidden along upon the top standard
rails by hand, so that the list shall be brought nearly up to the
cutter _i_, _i_, ready to commence the shearing operation; the bed is
then raised, which brings the cloth up against the edges of the shears.

[Illustration: 1226]

The construction of the bed will be seen by reference to the cross
section _fig._ 1226. It consists of an iron or other metal roller _k_,
_k_, turned to a truly cylindrical figure, and covered with cloth or
leather, to afford a small degree of elasticity. This roller is mounted
upon pivots in a frame _l_, _l_, and is supported by a smaller roller
_m_, similarly mounted, which roller _m_, is intended merely to prevent
any bending or depression of the central part of the upper roller or bed
_k_, _k_, so that the cloth may be kept in close contact with the whole
length of the cutting blades.

In order to allow the bed _k_ to rise and fall, for the purpose of
bringing the cloth up to the cutters to be shorn, or lowering it away
from them after the operation, the frame _l_, _l_, is made to slide up
and down in the grooved standard _n_, _n_, the movable part enclosed
within the standard being shown by dots. This standard _n_, is situated
about the middle of the machine, crossing it immediately under the
cutters, and is made fast to the frame _a_, by bolts and screws. There
is a lever _o_, attached to the lower cross-rail of the standard, which
turns upon a fulcrum-pin, the extremity of the shorter arm of which
lever acts under the centre of the sliding-frame, so that by the lever
_o_, the sliding-frame, with the bed, may be raised or lowered, and when
so raised, be held up by a spring catch _j_.

[Illustration: 1227]

It being now explained by what means the bed which supports the cloth is
constructed, and brought up, so as to keep the cloth in close contact
with the cutters, while the operation of shearing is going on; it is
necessary, in the next place, to describe the construction of the
cutters, and their mode of working; for which purpose, in addition to
what is shown in the first three figures, the cutters are also
represented detached, and upon a larger scale, in _fig._ 1227.

In this figure is exhibited a portion of the cutters in the same
situation as in _fig._ 1221.; and alongside of it is a section of the
same, taken through it at right angles to the former; _p_, is a metallic
bar or rib, somewhat of a wedge form, which is fastened to the top part
of the standard _a_, _a_, seen best in _fig._ 1220. To this bar a
straight blade of steel _g_, is attached by screws, the edge of which
stands forward even with the centre or axis of the cylindrical cutter
_i_, and forms the ledger blade, or lower fixed edge of the shears. This
blade remains stationary, and is in close contact with the pile or nap
of the cloth, when the bed _k_, is raised, in the manner above
described.

The cutter or upper blade of the shears, is formed by inserting two or
more strips of plate steel _r_, _r_, in twisted directions, into grooves
in the metallic cylinder _i_, _i_, the edges of which blades _r_, as the
cylinder _i_ revolves, traverse along the edge of the fixed or ledger
blade _g_, and by their obliquity produce a cutting action like shears;
the edges of the two blades taking hold of the pile or raised nap, as
the cloth passes under it, shaves off the superfluous ends of the wool,
and leaves the face smooth.

Rotatory motion is given to the cutting cylinder _i_, by means of a band
leading from the wheel _s_, which passes round the pulley fixed on the
end of the cylinder _i_, the wheel _s_ being driven by a band leading
from the rotatory part of a steam-engine, or any other first mover, and
passed round the rigger _t_, fixed on the axle _s_. Tension is given to
this band by a tightening pulley _u_, mounted on an adjustable
sliding-piece _v_, which is secured to the standard by a screw; and this
rigger is thrown in and out of geer by a clutch-box and lever, which
sets the machine going, or stops it.

In order to give a drawing stroke to the cutter, which will cause the
piece of cloth to be shorn off with better effect, the upper cutter has
a slight lateral action, produced by the axle of the cutting cylinder
being made sufficiently long to allow of its sliding laterally about an
inch in its bearings; which sliding is effected by a cam _w_, fixed at
one end. This cam is formed by an oblique groove, cut round the axle,
(see _w_, _fig._ 1227.) and a tooth _x_, fixed to the frame or standard
which works in it, as the cylinder revolves. By means of this tooth, the
cylinder is made to slide laterally, a distance equal to the obliquity
of the groove _w_, which produces the drawing stroke of the upper shear.
In order that the rotation of the shearing cylinder may not be
obstructed by friction, the tooth _x_, is made of two pieces, set a
little apart, so as to afford a small degree of elasticity.

The manner of passing the cloth progressively under the cutters is as
follows:--On the axle of the wheel _s_, and immediately behind that
wheel, there is a small rigger, from which a band passes to a wheel _y_,
mounted in an axle turning in bearings on the lower side-rail of the
standard _a_. At the reverse extremity of this axle, there is another
small rigger 1, from which a band passes to a wheel 2, fixed on the axle
3, which crosses near the middle of the machine, seen in _fig._ 1226.
Upon this axle there is a sliding pulley 4, round which a cord is passed
several times, whose extremities are made fast to the ends of the
sliding carriage _d_; when, therefore, this pulley is locked to the
axle, which is done by a clutch box, the previously described movements
of the machine cause the pulley 4 to revolve, and by means of the rope
passed round it, to draw the frame, with the cloth, slowly and
progressively along under the cutters.

It remains only to point out the contrivance whereby the machinery
throws itself out of geer, and stops its operations, when the edge of
the cloth or list arrives at the cutters.

At the end of one of the habiting rails _h_, there is a stop affixed by
a nut and screw 5, which, by the advance of the carriage, is brought up
and made to press against a lever 6; when an arm from this lever 6,
acting under the catch 7, raises the catch up, and allows the hand-lever
8, which is pressed upon by a strong spring, to throw the clutch-box 10,
out of geer with the wheel 8; whereby the evolution of the machine
instantly ceases. The lower part of the lever 6, being connected by a
joint to the top of the lever _j_, the receding of the lever 6, draws
back the lower catch _j_, and allows the sliding frame _l_, _l_, within
the bed _k_, to descend. By now turning the lower rollers _e_, _e_,
another portion of the cloth is brought up to be shorn; and when it is
properly habited and strained, by the means above described, the
carriage is slidden back, and, the parts being all thrown into geer, the
operation goes on as before.

Mr. Hirst’s improvements in manufacturing woollen cloths, for which a
patent was obtained in February, 1830, apply to that part of the process
where a permanent lustre is given usually by what is called
roll-boiling; that is, stewing the cloth, when tightly wound upon a
roller, in a vessel of hot water or steam. As there are many
disadvantages attendant upon the operation of roll-boiling, such as
injuring the cloths, by overheating them, which weakens the fibre of the
wool, and also changes some colours, he substituted, in place of it, a
particular mode of acting upon the cloths, by occasional or intermitted
immersion in hot water, and also in cold water, which operations may be
performed either with or without pressure upon the cloth, as
circumstances may require.

[Illustration: 1228 1229 1230]

The apparatus which he proposes to employ for carrying on his improved
process, is shown in the accompanying drawing. _Fig._ 1228. is a front
view of the apparatus, complete, and in working order; _fig._ 1229. is a
section, taken transversely through the middle of the machine, in the
direction of _fig._ 1230.; and _fig._ 1230. is an end view of the same;
_a_, _a_, _a_, is a vessel or tank, made of iron or wood, or any other
suitable material: sloping at the back and front, and perpendicular at
the ends. This tank must be sufficiently large to admit of half the
diameter of the cylinder or drum _b_, _b_, _b_, being immersed into it,
which drum is about four feet diameter, and about six feet long, or
something more than the width of the piece of cloth intended to be
operated upon. This cylinder or drum _b_, _b_, is constructed by
combining segments of wood cut radially on their edges, secured by
screw-bolts to the rims of the iron wheels, having arms, with an axle
passing through the middle.

The cylinder or drum being thus formed, rendered smooth on its
periphery, and mounted upon its axle in the tank, the piece of cloth is
wound upon it as tightly as possible, which is done by placing it in a
heap upon a stool, as at _c_, _fig._ 1229., passing its end over and
between the tension-rollers _d_, _e_, and then securing it to the drum,
the cloth is progressively drawn from the heap, between the
tension-rollers, which are confined by a pall and ratchet, on to the
periphery of the drum, by causing the drum to revolve upon its axis,
until the whole piece of cloth is tightly wound upon the drum; it is
then bound round with canvas or other wrappers, to keep it secure.

If the tank has not been previously charged with clean and pure water,
it is now filled to the brim, as shown at _fig._ 1229., and opening the
stopcock of the pipe _f_, which leads from a boiler, the steam is
allowed to blow through the pipe, and discharge itself at the lower end,
by which means the temperature of the water is raised in the tank to
about 170° Fahr. Before the temperature of the water has got up, the
drum is set in slow rotatory motion, in order that the cloth may be
uniformly heated throughout; the drum making about one rotation per
minute. The cloth, by immersion in the hot water, and passing through
the cold air, in succession, for the space of about eight hours, gets a
smooth soft face, the texture not being rendered harsh, or otherwise
injured, as is frequently the case by roll-boiling.

Uniform rotatory motion to the drum is shown in _fig._ 1228., in which
_g_ is an endless screw or worm, placed horizontally, and driven by a
steam-engine or any other first mover employed in the factory. This
endless screw takes into the teeth of, and drives, the vertical wheel
_h_, upon the axle of which the coupling-box _i_, _i_, is fixed, and,
consequently, continually revolves with it. At the end of the shaft of
the drum, a pair of sliding clutches _k_, _k_, are mounted, which, when
projected forward, as shown by dots in _fig._ 1228., produce the
coupling or locking of the drum-shaft to the driving wheel, by which the
drum is put in motion; but on withdrawing the clutches _k_, _k_, from
the coupling-box _i_, _i_, as in the figure, the drum immediately stands
still.

After operating upon the cloth in the way described, by passing it
through hot water for the space of time required, the hot water is to be
withdrawn by a cock at the bottom, or otherwise, and cold water
introduced into the tank in its stead; in which cold water the cloth is
to be continued turning, in the manner above described, for the space of
twenty-four hours, which will perfectly fix the lustre that the face of
the cloth has acquired by its immersion in the hot water, and leave the
pile or nap, to the touch, in a soft silky state.

In the cold-water operation he sometimes employs a heavy pressing roller
_l_, which, being mounted in slots in the frame or standard, revolve
with the large drum, rolling over the back of the cloth as it goes
round. This roller may be made to act upon the cloth with any required
pressure, by depressing the screws _m_, _m_, or by the employment of
weighted levers, if that should be thought necessary.

_Pressing_ is the last finish of cloth to give it a smooth level
surface. The piece is folded backwards and forwards in yard lengths, so
as to form a thick package on the board of a screw or hydraulic press.
Between every fold sheets of glazed paper are placed to prevent the
contiguous surfaces of cloth from coming into contact; and at the end of
every twenty yards, three hot iron plates are inserted between the
folds, the plates being laid side by side, so as to occupy the whole
surface of the folds. Thin sheets of iron not heated are also inserted
above and below the hot plates to moderate the heat. When the packs of
cloth are properly folded, and piled in sufficient number in the press,
they are subjected to a severe compression, and left under its influence
till the plates get cold. The cloth is now taken out and folded again,
so that the creases of the former folds may come opposite to the flat
faces of the paper, and be removed by a second pressure. In finishing
superfine cloths, however, a very slight pressure is given with iron
plates but moderately warmed. The satiny lustre and smoothness given by
strong compression with much heat is objectionable, as it renders the
surface apt to become spotted and disfigured by rain.


WOOTZ, is the Indian name of steel.


WORT, is the fermentable infusion of malt or grains. See BEER.


WOULFE’S APPARATUS, is a series of vessels, connected by tubes, for the
purpose of condensing gaseous products in water. See ACETIC ACID, _fig._
1.; also MURIATIC ACID.




X.


XANTHINE, is the name given by Kuhlmann to the yellow dyeing-matter
contained in madder.




Y.


YEAST, is the froth of fermenting worts. See BEER and FERMENTATION.


YELLOW DYE. (_Teinture jaune_, Fr.; _Gelbfarben_, Germ.) _Annotto_,
_dyer’s-broom_ (_Genista tinctoria_), _fustic_, _fustet_, _Persian or
French berries_, _quercitron bark_, _saw-wort_ (_Serratula tinctoria_),
_turmeric_, _weld_, and _willow leaves_, are the principal yellow dyes
of the vegetable kingdom; _chromate of lead_, _iron-oxide_, _nitric
acid_ (for silk), _sulphuret of antimony_, and _sulphuret of arsenic_,
are those of the mineral kingdom. Under these articles, as also under
CALICO-PRINTING, DYEING, and MORDANTS, ample instructions will be found
for communicating this colour to textile and other fibrous substances.
Alumina and oxide of tin are the most approved bases of the above
vegetable dyes. A nankin dye may be given with _bablah_, especially to
cotton oiled preparatory to the Turkey-red process. See MADDER.


YELLOW, KING’S, is a poisonous yellow pigment. See ARSENIC and ORPIMENT.


YTTRIA, is a rare earth, extracted from the minerals gadolinite and
yttrotantalite, being an oxide of the metal yttrium.




Z.


ZAFFRE. See COBALT.


ZEDOARY, is the root of a plant which grows in Malabar, Ceylon, &c. It
occurs in wrinkled pieces, externally ash-coloured, internally
brownish-red; possessed of a fragrant odour, somewhat resembling
camphor; and of a pungent, aromatic, bitterish taste. It contains,
according to Bucholz, 1·42 of volatile oil, of a burning camphorated
taste; 3·60 of a soft, bitter, aromatic resin; 11·75 of a bitter
aromatic extract, mixed with a little resin and potash-salts; 4·5 of
gum; 9 of vegetable mucilage; 3·60 of starch; 8·0 of a starchy extract
from the woody fibre, by means of caustic potassa, along with 31·2 of
another matter, 12·89 of woody fibre, and 15 of water. According to
Morin, this root, contains besides, an azotized substance, analogous to
the extract of beef.


ZIMOME, is a principle supposed by Taddei to exist in the gluten of
wheat-flour. Its identity is not recognised by later chemists.


ZIRCON. See HYACINTH and LAPIDARY.


ZIRCONIA, is a rare earth, extracted from the minerals zircon and
hyacinth; it is an oxide of zirconium, a substance possessing externally
none of the metallic characters, but resembling rather charcoal powder,
which burns briskly, and almost with explosive violence.


ZINC, is a metal of a bluish-white colour, of considerable lustre when
broken across, but easily tarnished by the air; its fracture is hackly,
and foliated with small facets, irregularly set. It has little cohesion,
and breaks in thin plates before the hammer, unless it has been
previously subjected to a regulated process of lamination, at the
temperature of from 220° to 300° F., whereby it becomes malleable, and
retains its malleability and ductility afterwards. On this singular
property, a patent was taken out by Messrs. Hobson and Sylvester, of
Sheffield, many years ago, for manufacturing sheet zinc, for covering
the roofs of houses, and sheathing ships; but the low price of copper at
that time, and its superior tenacity, rendered their patent ineffective.
The specific gravity of zinc varies from 6·9 to 7·2, according to the
condensation it has received. It melts under a red heat, at about the
680th or 700th degree of Fahrenheit’s scale. When exposed to this heat
with contact of air, the metal takes fire, and burns with a brilliant
bluish-white light, while a few flocculi, of a woolly-looking white
matter, rise out of the crucible, and float in the air. The result of
the combustion is a white powder, formerly called flowers, but now oxide
of zinc; consisting of 34 of metal, and 8 of oxygen, being their
respective prime equivalents; or, in 100 parts, of 81 and 19.

The principal ores of zinc are, the sulphuret called _blende_, the
silicate called _calamine_ and the sparry calamine, or the carbonate.

1. _Blende_ crystallizes in the garnet-dodecahedron; its fracture is
highly conchoidal; lustre, adamantine; colours, black, brown, red,
yellow, and green; transparent or translucent; specific gravity, 4. It
is a simple sulphuret of the metal; and, therefore, consists, in its
pure state, of 34 of zinc, and 16 of sulphur. It dissolves in nitric
acid, with disengagement of sulphuretted hydrogen gas. It occurs in beds
and veins, accompanied chiefly by galena, iron pyrites, copper pyrites,
and heavy spar. There is a radiated variety found at Przibram,
remarkable for containing a large proportion of cadmium. Blende is found
in great quantities in Derbyshire and Cumberland, as also in Cornwall.

2. _Calamine_, or silicate of zinc, is divided into two species; the
prismatic or electric calamine, and the rhomboidal; though they both
agree in metallurgic treatment. The _first_ has a vitreous lustre,
inclining to pearly; colour, white, but occasionally blue, green,
yellow, or brown; spec. grav. 3·38. It often occurs massive, and in
botroidal shapes. This species is a compound of oxide of zinc with
silica and water; and its constituents are--zinc oxide, 66·37; silica,
26·23; water, 7·4; in 100 parts. Reduced to powder, it is soluble in
dilute sulphuric or nitric acid, and the solution gelatinizes on
cooling. It emits a green phosphorescent light before the blowpipe. The
second species, or rhombohedral calamine, is a carbonate of zinc. Its
specific gravity is 4·442, much denser than the preceding. It occurs in
kidney-shaped, botroidal, stalactitic, and other imitative shapes;
surface generally rough, composition columnar. Massive, with a granular
texture, sometimes impalpable; strongly coherent. According to
Smithson’s analysis, Derbyshire calamine consists of--oxide of zinc,
65·2; carbonic acid, 34·8; which coincides almost exactly with a prime
equivalent of the oxide and acid, or 42 + 22 = 64.

The mineral genus called _zinc-ore_, or red oxide of zinc, is denser
than either of the above, its spec. grav. being 5·432. It is a compound
of oxide of zinc 88, and oxide of iron and manganese 12. It is found
massive, of a granular texture, in large quantities, in several
localities, in New Jersey. It is set free in several metallurgic
processes, and occurs crystallized in six-sided prisms of a yellow
colour, in the smelting-works of Kœnigshutte in Silesia, according to
Mitscherlich.

The zinc ores of England, like those of France, Flanders, and Silesia,
occur in two geological localities.

The first is in veins in the carboniferous or mountain limestone. The
blende and the calamine most usually accompany the numerous veins of
galena which traverse that limestone; though there are many lead mines
that yield no calamine; and, on the other hand, there are veins of
calamine alone, as at Matlock, whence a very considerable quantity of
this ore is obtained.

In almost every point of England where that metalliferous limestone
appears, there are explorations for lead and zinc ores. The
neighbourhood of Alston-moor in Cumberland, of Castleton and Matlock in
Derbyshire, and the small metalliferous belt of Flintshire, are
peculiarly marked for their mineral riches. On the north side of the
last county, calamine is mined in a rich vein of galena at Holywell,
where it presents the singular appearance of occurring only in the
ramifications that the lead vein makes from east to west, and never in
those from north to south; while the blende, abundantly present in this
mine, is found indifferently in all directions.

The second locality of calamine is in the magnesian limestone formation
of the English geologists, the alpine limestone of the French, and the
zechstein of the Germans. The calamine is disseminated through it in
small contemporaneous veins, which, running in all directions, form the
appearance of a network. These veins have commonly a thickness of only a
few inches; but in certain cases they extend to four feet, in
consequence of the union of several small ones into a mass. The
explorations of calamine in the magnesian limestone, are situated
chiefly on the flanks of the Mendip Hills, a chain which extends in a
north-west and south-east direction, from the canal of Bristol to Frome.
The calamine is worked mostly in the parishes of Phipham and Roborough,
as also near Rickford and Broadfield-Doron, by means of a great
multitude of small shafts. The miners pay, for the privilege of working,
a tax of 1_l._ sterling per annum to the Lords of the Treasury; and they
sell the ores, mixed with a considerable quantity of carbonate of lime,
for 1_l._ per ton, at Phipham, after washing it slightly in a sieve.
They are despatched to Bristol, where they receive a new washing, in
order to separate the galena.

OF THE SMELTING OF THE ORES OF ZINC.

The greater part of the zinc works are situated in the neighbourhood of
Birmingham and Bristol. The manufacture of brass, which has been long
one of the staple articles of these towns, was probably the cause of the
introduction of this branch of industry, at the period when brass began
to be made by the direct union of copper with metallic zinc, instead of
calamine. A few zinc furnaces exist also in the neighbourhood of
Sheffield, amid the coal-pits surrounding that town. Bristol and
Birmingham derive their chief supply of ores from the Mendip Hills and
Flintshire; and Sheffield, from Alston-moor.

The calamine, freed from the galena by sorting with the hand, is
calcined before its introduction into the smelting-furnaces, by being
exposed, coarsely bruised, in reverberatory ovens, 10 feet long, and 8
broad, in a layer 6 inches thick. In some establishments the calcination
is omitted, and the calamine, broken into pieces about the size of a
pigeon’s egg, is mixed with its bulk of small coal.

Zinc is smelted in England, likewise from blende (sulphuret of zinc).
This ore, after being washed, and broken into pieces of the size of a
filbert, was sold a few years ago at the mine of Holywell for 3_l._ a
ton, or half the price of calamine. It is roasted, without any other
preparation, in reverberatory furnaces; which are about 8 feet wide, and
10 long; the distance between the roof and the sole being 30 inches, and
the height of the fire-bridge 18. The layer of blende, which is placed
on the hearth, is about 4 or 5 inches thick; and it is continually
stirred up with rakes. One ton of it requires, for roasting, four tons
of coals; and it suffers a loss of 20 per cent. The operation takes from
10 to 12 hours. The mixture of reducing consists of one-fourth part of
the desulphuretted oxide, one-fourth of calcined calamine, and one-half
part of charcoal; which affords commonly 30 per cent. of zinc.

[Illustration: 1231 1232]

The English furnaces for smelting zinc ores are sometimes quadrangular,
sometimes round; the latter form being preferable. They are mounted with
from 6 to 8 crucibles or pots (see _fig._ 1231.), arched over with a
cupola _a_, placed under a conical chimney _b_, which serves to give a
strong draught, and to carry off the smoke. In this cone there are as
many doors _c_, _c_, _c_, as there are pots in the furnace; and an equal
number of vents _d_, _d_, _d_, in the cupola, through which the smoke
may escape, and the pots may be set. In the surrounding walls there are
holes for taking out the pots, when they become unserviceable; after the
pots are set, these holes are bricked up. The pots are heated to
ignition in a reverberatory furnace before being set, and are put in by
means of iron tong machinery supported upon two wheels, as is the case
with glass-house pots, _e_, is the grate; _f_, the door for the fuel;
_g_, the ash-pit. The pots _h_, _h_, _h_, have a hole in the centre of
their bottom, which is closed with a wooden plug, when they are set
charged with calamine, mixed with one-seventh of coal; which coal
prevents the mixture from falling through the orifice, when the heat
rises and consumes the plug. The sole of the hearth _i_, _i_, upon which
the crucibles stand, is perforated under each of them, so that they can
be reached from below; to the bottom orifice of the pot, when the
distillation begins, a long sheet-iron pipe _k_, is joined, which dips
at its end into a water-vessel _l_, for receiving in drops the condensed
vapours of the zinc. The pot is charged from above, through an orifice
in the lid of the pot, which is left open after the firing, till the
bluish colour of the flame shows the volatilization of the metal;
immediately whereupon the hole is covered with a fire-tile _m_. The iron
tubes are apt to get obstructed during the distillation, and must
therefore be occasionally cleared out with a redhot rod. When the
distillation is finished, the iron pipes must be removed; the coaly and
other contents of the pot cleared away. A pot lasts about four months
upon an average. Five distillations may be made in the course of 14
days, in which from 6 to 10 tons of calamine may be worked up, and from
22 to 24 tons of coals consumed, with a product of two tons of zinc. The
metal amounts to from 25 to 40 per cent. of the ore.

1, 2, is the level of the upper floor; 3, 4, level of the lower ceiling
of the lower floor.

_Fig._ 1232., ground plan on the level of 1, 2: only one-half is here
shown.

The zinc collected in this operation, is in the form of drops, and a
very fine powder, mingled with some oxide. It must be melted in an iron
pot or boiler, set in a proper furnace; and the oxide is skimmed off the
surface, to be returned into the crucibles. The metal is, lastly, cast
into square bars or ingots.

The crucibles are discharged at the end of each operation, by
withdrawing the condenser, breaking with a rake the piece of charcoal
which shuts their bottom, and then emptying them completely, by shaking
their upper part. In replacing the condenser-pipe _k_ (see second pot
from the right hand, _fig._ 1231), the flange at its top is covered with
a ring of loam-lute, pressed against the conical bottom of the crucible,
and secured in its place by means of two parallel rods _o_, _o_, which
can be clamped by screws projecting horizontally from the vertical
tunnel. See their places, indicated by two open dots near _o_, _o_.

A smelter and two labourers are employed in conducting a furnace; who
make, with a mixture of equal parts of fire-clay, and cement of old
pounds finely ground, the pots or crucibles, which last about four
months. Five charges are made in 15 days; these work up from 6 to 10
tons of calamine, consume from 22 to 24 tons of coals, and produce 2
tons of zinc, upon an average. The following estimate of prices was made
a few years ago:--

  3 tons of calamine, at _£_6.        _£_18  0  0
  24 ditto coal, at 5_s._                 6  0  0
  A smelter, at 2 guineas a week          2  2  0
  Two labourers, each at 4_s._ per day    2 16  0
  Incidental expenses                     1  0  0
                                         --------
                                      _£_29 18  0

The calamine of Alston-moor, used at Sheffield, is not so rich; it
produces at most only 25 per cent. of zinc. The coals are laid down at a
cost of 5_s._ 8_d._ per ton; and the calamine laid down there 5_l._;
whence the zinc will amount to 32_l._ 14_s._ per ton. The considerable
importations of zinc from Belgium and Germany, for some years back, have
caused a considerable fall in its price.

At Lüttich, where the calamine of Altenberg, near Aix-la-Chapelle, is
smelted, a reduction furnace, containing long horizontal earthen tubes,
is employed. The roasted calamine is finely ground, and mixed with from
one-third to two-thirds its volume of coke or charcoal, broken to pieces
the size of nuts.

[Illustration: 1233 1234]

_Fig._ 1233. represents this zinc furnace in elevation; and _fig._ 1234.
in a vertical section through the middle. From the hearth to the bottom
of the chimney it is 9 feet high, and the chimney itself is 18 or 20
feet high. _a_, is the ash-pit; _b_, the grate; _c_, the fireplace; _d_,
the hearth; _e_, _e_, the laboratory; _f_, the upper arch, which closes
in the laboratory; _f_, the second arch, which forms the hood-cap of the
furnace; _g_, the chimney; _h_, the fire-wall, which rests against a
supporting wall of the smelting-house. Through the vaulted hearth the
flame of the fire draws through ten flues _i_, _i_, two placed in one
line; betwixt these 5 pairs of draught openings, upon the sole of the
hearth, the undermost earthen tubes _k_, immediately rest. The second
and third rows of tubes _k_, _k_, lie in a parallel direction over each
other, at about one inch apart; in the sixth row there are only two
tubes; so that there are 22 tubes altogether in one furnace. At their
two ends these tubes rest upon fire-tiles, which form, with the
side-walls, a kind of checquer-work _l_, _l_. The tubes are 4 feet long,
4 to 5 inches in diameter within, 5/4 of an inch thick. The fire, which
arrives at the laboratory through the flues _i_, _i_, plays round the
tubes, and passes off through the apertures _m_, _m_, in both arches of
the furnace, into the chimney. _n_, is an opening in the front wall
between the two arches, which serves to modify the draught, by admitting
more or less of the external air.

The two slender side walls _o_, _o_, of the furnace, are a foot distant
from the chequer-work, so that on the horizontal iron bars _q_, _q_,
supported by the hooks _p_, _p_, the iron receivers _r_, _r_, may have
room to rest at their fore part. These receivers are conical pipes of
cast iron, 1-1/2 foot long, posteriorly 1-1/2 inch, and anteriorly 1
inch wide at the utmost. After the earthen tubes have been filled with
the ore to be smelted, these conical pipes are luted to them in a
slightly slanting position. These cones last no more than three weeks;
and are generally lengthened with narrow-mouthed wrought-iron tubes, to
prevent the combustion of the zinc, by contact of air. When the furnace
is in activity, a blue flame is to be seen at the mouths of all these
pipes. Every two hours the liquefied metal is raked out into a shovel
placed beneath; and in 12 hours the charge is distilled; after which the
tubes are cleared out, and re-charged. 100 pounds of metallic zinc are
the product of one operation. It is remelted at a loss of 10 per cent.,
and cast into moulds for sale.

[Illustration: 1235 1236]

_Fig._ 1235. is a longitudinal section of the furnace for calcining
calamine in Upper Silesia; _fig._ 1236. is a ground-plan of the furnace.
_a_, is the orifice in the vault or dome, for the introduction of the
ore; _b_, _b_, apertures in the side-walls, shut with doors, through
which the matter may be turned over; _c_, the chimney; _d_, the
fire-bridge; _e_, the grate; _f_, the feed opening of the fire, the fuel
being pitcoal. The calamine is stirred about every hour; and after being
well calcined during 5 or 6 hours, it is withdrawn; and a new charge is
put in. These Silesian furnaces admit of 30 cwt. at a time; and for
roasting every 100 cwt. 15 Prussian bushels of fuel, equal to 23 English
bushels, are employed. These calcining furnaces are sometimes built
alongside of the zinc smelting-furnaces, and are heated by the waste
flame of the latter. The roasting is performed in the Netherlands in
shafts, like small blast iron-furnaces, called schachtofen.

[Illustration: 1237 1238]

The hearth _a_, in _figs._ 1237, 1238., is constructed for working with
5 muffles, one of which is long, and four short. The muffles are made
upon moulds, of fire-clay mixed with ground potsherds. The receivers are
stoneware bottles. The grate is 10 inches beneath the level of the
hearth. _b_, the fire-bridge, is proportionally high, to diminish the
force of the flame upon the hearth, that it may not strike the muffles.
_c_, is the opening through which the muffles are put in and taken out;
during the firing it is partly filled with bricks, so that the smoke and
flame may escape between them; _d_, _d_, are openings for adjusting the
positions of the muffles; _e_, cross hoops of iron, to strengthen the
brick arch; _f_, is a bed of sand under the sole of the hearth. During
the first two days, the fire is applied under the grating; the heat must
be very slowly raised to redness, at which pitch it must be maintained
during two days. From 8 to 10 days are required for the firing of the
muffles.

[Illustration: 1239 1240 1241]

The furnace shown in _figs._ 1239, 1240, 1241. is for the melting of the
metallic zinc. _Fig._ 1240. is a front view; _fig._ 1239. a transverse
section; _fig._ 1241. a view from above: _a_, is the fire-door; _b_, the
grate; _c_, the fire-bridge; _d_, the flue; _e_, the chimney; _f_, _f_,
_f_, cast-iron melting-pots, which contain each about 10 cwt. of the
metal. The heat is moderated by the successive addition of pieces of
cold zinc. The inside of the pots should be coated with loam, to prevent
the iron being attacked by the zinc. When the zinc is intended to be
laminated, it should be melted with the lowest possible heat, and poured
into hot moulds.

When the zinc ores contain cadmium, this metal distils over in the form
of brown oxide, with the first portions, being more volatile than zinc.

Under BRASS and COPPER, the most useful alloys of zinc are described.
The sulphate, vulgarly called white vitriol, is made from the sulphuret,
by roasting it gently, and then exposing it upon sloping terraces to the
action of air and moisture, as has been fully detailed under SULPHATE OF
IRON. The purest sulphate of zinc is made by dissolving the metal in
dilute sulphuric acid, digesting the solution over some of the metal,
filtering, evaporating, and crystallizing.

Sulphate of zinc is added as a drier to japan varnishes.

The ordinary zinc found in the market is never pure; but contains lead,
cadmium, arsenic, copper, iron, and carbon; from some of which, it may
be freed in a great degree by distillation; but even after this process
it retains a little lead, with all the arsenic and cadmium. The
separation of the latter is described under CADMIUM. Zinc, free from
other metals, may be obtained by distilling a mixture of charcoal and
its subcarbonate, precipitated from the crystallized sulphate by
carbonate of soda. By holding a porcelain saucer over the flame of
hydrogen produced from the action of dilute sulphuric acid upon any
sample of the zinc of commerce, the presence of arsenic in it may be
made manifest by the deposit of a gray film of the latter metal.
Antimony, however, produces a somewhat similar effect to arsenic.

Zinc is extensively employed for making water-cisterns, baths, spouts,
pipes, plates for the zincographer, for voltaic batteries, filings for
fire-works, covering roofs, and a great many architectural purposes,
especially in Berlin; because this metal, after it gets covered with a
thin film of oxide or carbonate, suffers no further change by long
exposure to the weather. One capital objection to zinc as a roofing
material, is its combustibility.

Chloride of zinc has been recently used with great advantage as an
escharotic for removing cancerous tumours, and healing various
ill-constitutioned ulcers. It, as also the nitrate, forms an ingredient
in the resist pastes for the pale blues of the indigo vat.

Spelter (zinc) imported for home consumption--in 1835, 52,604 cwts.; in
1836, 47,406 cwts. Duty,--in cakes, 2_s._; not in cakes, 10_s._ per cwt.


THE END.


  LONDON:
  Printed by A. SPOTTISWOODE
  New-Street-Square




Alphabetical List of Articles.


ABB-WOOL -- ACETATE -- ACETATE OF ALUMINA -- ACETIC ACID -- ACETIMETER
-- ACETONE -- ACID OF ARSENIC -- ACIDS -- ACROSPIRE -- ADDITIONS --
ADIPOCIRE -- ADIT -- ADULTERATION -- ÆTHER -- AFFINITY -- AGARIC --
AGATE -- AIR -- ALABASTER -- ALBUM GRÆCUM -- ALCARAZZAS -- ALCOHOL --
ALE -- ALEMBIC -- ALEMBROTH -- ALGAROTH -- ALIZARINE -- ALKALI --
ALKALIMETER -- ALKANA -- ALKANET -- ALLIGATION -- ALLOY -- ALMOND --
ALMOND OIL -- ALOE -- ALUDEL -- ALUM -- AMADOU -- AMALGAM --
AMALGAMATION -- AMBER -- AMBERGRIS -- AMIANTHUS -- AMMONIA -- AMMONIAC
-- AMORPHOUS -- ANALYSIS -- ANCHOR -- ANIMÉ -- ANKER -- ANNEALING or
NEALING -- ANNOTTO -- ANTHRACITE -- ANTIGUGGLER -- ANTIMONY --
ANTISEPTICS -- ANVIL -- AQUA REGIA -- AQUA VITÆ -- AQUAFORTIS -- ARCHIL
-- ARDENT SPIRIT -- AREOMETER OF BAUMÉ -- ARGILLACEOUS EARTH -- ARGOL --
ARMS -- ARRACK -- ARROW ROOT -- ARSENIC -- ARTESIAN WELLS -- ASPHALTUM
-- ASSAY and ASSAYING -- ATOMIC WEIGHTS or ATOMS -- ATTAR OF ROSES --
AURUM MUSIVUM -- AUTOMATIC -- AUTOMATON -- AXE -- AXLES -- AXUNGE --
AZOTIZED -- AZURE

BABLAH -- BAGASSE -- BAKING -- BALANCE -- BALSAMS -- BANDANNA --
BARBERRY -- BARILLA -- BARIUM -- BARK OF OAK -- BARLEY -- BARM -- BARYTA
or BARYTES -- BASSORINE -- BATHS -- BDELLIUM -- BEER -- BEET-ROOT SUGAR
-- BELL-METAL -- BELLOWS -- BEN OIL -- BENGAL STRIPES -- BENJAMIN or
BENZOIN -- BERLIN BLUE -- BERRIES OF AVIGNON -- BERYL -- BEZOAR -- BILE
-- BIRDLIME -- BISMUTH -- BISTRE -- BITTER PRINCIPLE -- BITUMEN, or
ASPHALTUM -- BLACK DYE -- BLACK PIGMENT -- BLEACHING -- BLENDE -- BLOCK
MANUFACTURE -- BLOOD -- BLOWING MACHINE -- BLOWPIPE -- BLUE DYES -- BLUE
PIGMENTS -- BLUE VITRIOL -- BOMBAZINE -- BONE BLACK -- BONES --
BOOKBINDING -- BORAX -- BOTTLE MANUFACTURE -- BOUGIE -- BRACES --
BRAIDING MACHINE -- BRAN -- BRANDY -- BRASS -- BRAZIL-WOOD -- BRAZING --
BREAD -- BRECCIA -- BREWING -- BRICK -- BRIMSTONE -- BRITISH GUM --
BROMINE -- BRONZE -- BROWN DYE -- BRUSHES -- BUTTER -- BUTTER OF CACAO
-- BUTTON MANUFACTURE

CABLE -- CACAO, BUTTER OF -- CADMIUM -- CAFEINE -- CAJEPUT OIL --
CALAMANCO -- CALAMINE -- CALC-SINTER -- CALC-TUFF -- CALCAREOUS EARTH --
CALCAREOUS SPAR -- CALCEDONY -- CALCHANTUM -- CALCINATION -- CALCIUM --
CALCULUS -- CALENDER -- CALICO-PRINTING -- CALOMEL -- CALORIC --
CALORIFÈRE OF WATER -- CAMBRIC -- CAMLET OR CAMBLET -- CAMPHOR, or
CAMPHIRE -- CAMWOOD -- CANDLE -- CANE-MILL -- CANNON -- CANVASS --
CAOUTCHOUC, GUM-ELASTIC, OR INDIAN-RUBBER -- CAPERS -- CAPSTAN -- CARAT
or CARACT -- CARBON -- CARBONATE OF AMMONIA -- CARBONATED WATER --
CARBONATES -- CARBONIC ACID -- CARBONIC OXIDE -- CARBUNCLE -- CARBURET
OF SULPHUR -- CARBURETTED HYDROGEN -- CARD CUTTING -- CARDS -- CARDS,
PLAYING -- CARMINE -- CARPET -- CARTHAMUS -- CASE-HARDENING -- CASHMERE
or CACHEMERE -- CASK -- CASSAVA -- CASSIS -- CASTING OF METALS -- CASTOR
-- CASTOR OIL -- CASTOR or CASTOREUM -- CASTORINE -- CATECHU -- CATGUT
-- CATHARTINE -- CAUSTIC -- CAVIAR -- CAWK -- CEDRA -- CELESTINE --
CEMENTATION -- CEMENTS -- CERASIN -- CERATE -- CERINE -- CERIUM --
CERUSE -- CETINE -- CHAINWORK -- CHALK -- CHALK--Black -- CHALK--French
-- CHALK--Red -- CHARCOAL -- CHICA -- CHIMNEY -- CHINTZ -- CHLORATE OF
POTASH -- CHLORATES -- CHLORIC ACID -- CHLORINE -- CHLOROMETRY --
CHOCOLATE -- CHROMATES -- CHROMIC ACID -- CHROMIUM -- CINNABAR --
CINNAMON -- CITRIC ACID -- CIVET -- CLAY -- CLOTH-BINDING -- CLOTH,
MANUFACTURE OF -- COBALT -- COCCULUS INDICUS, or Indian berry --
COCHINEAL -- COCOA, STEARINE, AND ELAINE -- COFFEE -- COKE -- COLCOTHAR
OF VITRIOL -- COLOPHANY -- COLOURING MATTER -- COLUMBIUM -- COLZA --
COMB -- COMBINATION -- COMBUSTIBLE -- COMBUSTION -- COMPOUND COLOURS --
CONCRETE -- CONGELATION -- COOLING OF FLUIDS -- COPAL -- COPPER --
COPPER, Statistics of -- COPPERAS -- CORAL -- CORK -- CORROSIVE
SUBLIMATE -- CORUNDUM; or Telesie -- COTTON DYEING -- COTTON MANUFACTURE
-- COURT PLASTER -- CRAPE -- CRAYONS -- CRAYONS, lithographic --
CREOSOTE -- CRUCIBLES -- CRYSTAL -- CUDBEAR -- CUPELLATION -- CURRYING
OF LEATHER -- CUTLERY -- CYANATES -- CYANHYDRIC Acid -- CYANIDES --
CYANIDES, FERRO -- CYANOGEN -- CYDER

DAHLINE -- DAMASCUS BLADES -- DAMASK -- DAMASKEENING -- DAMASSIN --
DAMPS -- DAPHNINE -- DATOLITE -- DECANTATION -- DECOCTION --
DECOMPOSITION -- DECREPITATION -- DEFECATION -- DEFLAGRATION --
DELIQUESCENT -- DELPHINIA -- DEPHLEGMATION -- DEPHLOGISTICATED --
DEPILATORY -- DETONATION -- DEUTOXIDE -- DEXTRINE -- DIAMOND -- DIAMOND
MICROSCOPES -- DIAMONDS, cutting of -- DIAPER -- DIASTASE -- DIES FOR
STAMPING -- DIGESTER -- DIMITY -- DISTILLATION -- DOCIMACY -- DORNOCK --
DRAGON’S BLOOD -- DRUGGET -- DRYING HOUSE -- DUCTILITY -- DUNGING --
DYEING

EARTHS -- EAU DE COLOGNE -- EAU DE LUCE -- EBULLITION -- EDGE-TOOLS --
EDULCORATE -- EFFERVESCENCE -- EFFLORESCENCE -- EGGS, HATCHING --
EIDER-DOWN -- ELAINE -- ELASTIC BANDS -- ELECTIVE AFFINITY -- ELEMENTS
-- ELEMI -- ELUTRIATE -- EMBALMING -- EMBOSSING CLOTH -- EMBOSSING WOOD
-- EMBROIDERING MACHINE -- EMERALD -- EMERY -- EMPYREUMA -- ENAMELS --
EPSOM SALTS -- EQUIVALENTS, CHEMICAL -- ESSENCE D’ORIENT -- ESSENCES --
ETCHING Varnish -- ETHER -- ETHER, Acetic -- ETHIOPS -- EUDIOMETER --
EVAPORATION -- EXPANSION -- EXTRACTS

FAHLERZ -- FAINTS -- FAN -- FARINA -- FATS -- FAULTS -- FEATHERS --
FECULA -- FELSPAR -- FELTING -- FERMENT -- FERMENTATION -- FERROCYANATE,
or, FERROCYANIDE -- FERROPRUSSIATES -- FIBRE, VEGETABLE -- FIBRINE --
FILE -- FILLIGREE -- FILTRATION -- FIRE ARMS, MANUFACTURE OF --
FIRE-DAMP -- FIRE-WORKS -- FISH-HOOKS -- FLAKE WHITE -- FLAME -- FLANNEL
-- FLAX -- FLINT -- FLOSS -- FLOSS-SILK -- FLOUR -- FLOUR OF WHEAT,
Adulterations of, to Detect -- FLOWERS -- FLOWERS, ARTIFICIAL,
MANUFACTURE OF -- FLUATES -- FLUOR SPAR -- FLUX -- FLY POWDER -- FODDER
-- FONDUS -- FORGE -- FORMIATES -- FORMIC ACID -- FORMULÆ, CHEMICAL --
FOUNDING -- FOUNTAIN -- FOXING -- FRANKFORT BLACK -- FREEZING -- FRENCH
BERRIES -- FRICTION, counteraction of -- FRIT -- FUEL -- FULGURATION --
FULLER’S EARTH -- FULLING -- FULLING MILL -- FULMINATES -- FULMINIC ACID
-- FUMIGATION -- FUR -- FURNACE OF ASSAY -- FUSIBILITY -- FUSIBLE METAL
-- FUSTET -- FUSTIAN -- FUSTIC

GABRONITE -- GADOLINITE -- GALACTOMETER, or LACTOMETER -- GALBANUM --
GALENA -- GALIPOT -- GALL OF ANIMALS, or OX-GALL, purification of --
GALL OF GLASS -- GALL-NUTS, or GALLS -- GALLATES -- GALLIC ACID --
GALLIPOLI OIL -- GALVANIZED IRON -- GAMBOGE -- GANGUE -- GARNET -- GAS
-- GAS-HOLDER -- GAS-LIGHT -- GASOMETER -- GAUZE WIRE CLOTH --
GAY-LUSSITE -- GELATINE -- GEMS -- GEOGNOSY -- GERMAN SILVER --
GERMINATION -- GIG MACHINES -- GILDING -- GIN, or Geneva, -- GINNING --
GLANCE COAL -- GLASS -- GLASS CUTTING AND GRINDING -- GLASS MAKING --
GLAUBER SALT -- GLAZES -- GLAZIER -- GLOVE MANUFACTURE -- GLOVE-SEWING
-- GLUCINA -- GLUE -- GLUTEN -- GLYCERINE -- GNEISS -- GOLD --
GONG-GONG; or tam-tam -- GONIOMETER -- GRADUATOR -- GRANITE --
GRANULATION -- GRAPHITE -- GRAUWACKE or GREYWACKE -- GRAY DYE -- GREEN
DYE -- GREEN PAINTS -- GREEN VITRIOL -- GUAIAC -- GUANO -- GUM -- GUM
RESINS -- GUNPOWDER -- GYPSUM

HADE -- HAIR -- HAIR PENCILS OR BRUSHES -- HALOGENE -- HANDSPIKE --
HARDNESS -- HARTSHORN, SPIRIT OF -- HAT MANUFACTURE -- HATCHING OF
CHICKENS -- HEALDS -- HEARTH -- HEAT -- HEAT-REGULATOR -- HEAVY SPAR --
HECKLE -- HELIOTROPE -- HEMATINE -- HEMATITE -- HEMP -- HEPAR -- HEPATIC
AIR -- HERMETICAL SEAL -- HIDE -- HIRCINE -- HOG’s LARD -- HONEY --
HONEY-STONE -- HOP -- HORDEINE -- HORN -- HORNSILVER -- HORNSTONE --
HORSE POWER -- HOSIERY -- HOT-FLUE -- HYDRATES -- HYDRAULIC PRESS --
HYDRIODIC ACID -- HYDROCHLORIC ACID -- HYDROGEN -- HYDROMETER --
HYDROSULPHURETS -- HYMEN[OE]A COURBARIL -- HYOSCIAMUS NIGER --
HYPEROXYMURIATES -- HYPOSULPHATES; HYPOSULPHITES

ICEHOUSE -- IMPERMEABLE -- INCOMBUSTIBLE CLOTH -- INCUBATION, ARTIFICIAL
-- INDIAN RUBBER -- INDIGO -- INK -- INULINE -- IODINE -- IRIDIUM --
IRON -- ISINGLASS, or Fish-glue -- ISLAND MOSS -- IVORY -- IVORY BLACK

JACK -- JACK and JACK-SINKERS -- JACK-BACK -- JACQUARD -- JADE --
JAPANNING -- JASPER -- JELLY, ANIMAL -- JELLY, VEGETABLE -- JET --
JEWELLERY, Art of.

KALI -- KAOLIN -- KARABÉ -- KELP -- KERMES -- KILLAS -- KILN -- KINIC
ACID -- KINO -- KIRSCHWASSER -- KNOPPERN -- KOUMISS

LABDANUM or LADANUM -- LABRADORITE, OPALINE or LABRADORE FELSPAR --
LABYRINTH -- LAC, LAC-DYE -- LACCIC ACID -- LACCINE -- LACE MANUFACTURE
-- LACQUER -- LACTIC ACID -- LACTOMETER -- LAKES -- LAMINABLE -- LAMIUM
ALBUM -- LAMP OF DAVY -- LAMP-BLACK -- LAMPATES and LAMPIC ACID -- LAMPS
-- LAPIDARY, Art of -- LAZULITE -- LEAD -- LEAD-SHOT -- LEATHER -- LEDUM
PALUSTRE -- LEGUMINE -- LEMONS -- LEUCINE -- LEUCITE -- LEVIGATION --
LEWIS -- LIAS -- LIBAVIUS, LIQUOR OF -- LICHEN. -- LIGNEOUS MATTER --
LIGNITE -- LILAC DYE -- LIMESTONE -- LINEN -- LINSEED -- LIQUATION --
LIQUEURS, LIQUORISTE -- LIQUID AMBER -- LITHARGE -- LITHIA -- LITHIUM --
LITHOGRAPHY -- LITMUS -- LIXIVIATION -- LOADSTONE, MAGNETIC IRON-STONE
-- LOAM -- LODE -- LOGWOOD -- LOOM -- LUBRICATION -- LUPININE --
LUPULINE -- LUTE -- LUTEOLINE -- LYCOPODIUM CLAVATUM -- LYDIAN STONE

MACARONI -- MACE -- MACERATION -- MACLE -- MADDER -- MADREPORES --
MAGISTERY -- MAGISTRAL -- MAGMA -- MAGNANIER -- MAGNESIA -- MAGNESIA,
NATIVE -- MAGNESIAN LIMESTONE -- MAGNESITE -- MAGNET, NATIVE -- MAHALEB
-- MALACHITE -- MALATES -- MALIC ACID -- MALLEABILITY -- MALT -- MALT
KILN -- MALTHA -- MANGANESE -- MANGLE -- MANIOC -- MANNA -- MARBLE --
MARCASITE -- MARGARATES -- MARGARIC ACID -- MARINE ACID -- MARINE SALT
-- MARL -- MARQUETRY -- MARTIAL -- MASSICOT -- MASTIC -- MATRASS --
MATTE -- MEADOW ORE -- MEDALS -- MEERSCHAUM -- MELLITE -- MELLITIC ACID
-- MELLON -- MENACHANITE -- MERCURY or QUICKSILVER -- MERCURY,
BICHLORIDE OF -- MERCURY, PROTOCHLORIDE OF -- METALLURGY -- METALS --
METEORITES -- METHYLÈNE -- MICA -- MICROCOSMIC SALT -- MILK --
MILL-STONE, or BUHR-STONE -- MINERAL WATERS -- MINES -- MINIUM -- MINT
-- MIRRORS -- MISPICKEL -- MOHAIR -- MOIRÉE METALLIQUE -- MOLASSE --
MOLASSES -- MOLYBDENUM -- MORDANT (adhesive) -- MORDANT (colouring) --
MOROCCO -- MORPHIA -- MORTAR, HYDRAULIC -- MOSAIC -- MOSAIC GOLD --
MOTHER OF PEARL -- MOTHER-WATER -- MOUNTAIN SOAP -- MUCIC ACID --
MUCILAGE -- MUFFLE -- MUNDIC -- MUNJEET -- MURIATES -- MURIATIC or
HYDROCHLORIC ACID -- MUSK -- MUSLIN -- MUST -- MUSTARD -- MUTAGE --
MYRICINE -- MYRRH

NACARAT -- NAILS, MANUFACTURE OF -- NANKIN -- NAPHTHA, or ROCK-OIL --
NAPHTHALINE -- NAPLES YELLOW -- NATRON -- NEALING -- NEB-NEB -- NEEDLE
MANUFACTURE -- NEROLI -- NET -- NEUTRALIZATION -- NICARAGUA WOOD --
NICKEL -- NICOTIANINE -- NICOTINE -- NITRATE OF AMMONIA -- NITRATE OF
LEAD -- NITRATE OF POTASH -- NITRATE OF SILVER -- NITRATE OF SODA --
NITRATE OF STRONTIA -- NITRIC ACID -- NITRO-MURIATIC ACID -- NITROGEN
GAS, or AZOTE -- NITROGEN, DEUTOXIDE OF -- NITROGEN, PROTOXIDE OF --
NITROUS ACID -- NOPAL -- NUT OIL -- NUTMEG -- NUX VOMICA

OAK BARK -- OATS -- OBSIDIAN -- OCHRE -- OIL OF VITRIOL -- OILS -- OILS,
VOLATILE OR ESSENTIAL; Manufacture of -- OLEATES -- OLEFIANT GAS --
OLEIC ACID -- OLEINE -- OLIBANUM -- OLIVE OIL -- ONYX -- OOLITE -- OOST,
or OAST -- OPAL -- OPERAMETER -- OPIUM -- OPOBALSAM -- OPOPONAX --
ORANGE DYE -- ORCINE -- ORES -- ORPIMENT -- ORYCTNOGNOSY -- OSMIUM --
OSTEOCOLLA -- OXALATES -- OXALIC ACID -- OXIDES -- OXISELS -- OXYGEN

PACKFONG -- PACO, or PACOS -- PADDING MACHINE -- PAINT -- PAINTS,
GRINDING OF -- PAINTS, VITRIFIABLE -- PALLADIUM -- PALM OIL -- PAPER
CUTTING -- PAPER-HANGINGS -- PAPER, MANUFACTURE OF -- PARAFFINE --
PARCHMENT -- PARTING -- PASTEL (colour) -- PASTEL (crayon) -- PASTES, or
FACTITIOUS GEMS -- PASTILLE (perfumery) -- PASTILLE (tablet) --
PE-TUNT-SE -- PEARLASH -- PEARLS -- PEARLS, ARTIFICIAL -- PEARLWHITE --
PECTIC ACID -- PECTINE -- PELTRY -- PENCIL MANUFACTURE -- PENS, STEEL --
PEPPER -- PERFUMERY, ART OF -- PERRY -- PERSIAN BERRIES -- PETROLEUM --
PEWTER, PEWTERER -- PHOSPHORIC ACID -- PHOSPHORUS -- PICAMARE --
PICROMEL -- PICROTOXINE -- PIGMENTS, VITRIFIABLE -- PIMENTO -- PIN
MANUFACTURE -- PINCHBECK -- PINE-APPLE YARN and CLOTH -- PINEY TALLOW --
PIPERINE -- PITCH of wood-tar -- PITCH, MINERAL -- PITCOAL -- PITCOAL,
COKING OF -- PITTACALL -- PLASTER -- PLASTER OF PARIS -- PLATED
MANUFACTURE -- PLATINA-MOHR -- PLATINUM -- PLUMBAGO -- PLUSH -- POINT
NET -- PORCELAIN -- PORPHYRY -- PORTER -- PORTLAND STONE -- POTASH, or
POTASSA -- POTASSIUM -- POTATO -- POTTERY, PORCELAIN. -- PRECIPITATE --
PRECIPITATION -- PRESS, HYDRAULIC -- PRINCE’S METAL, or Prince Rupert’s
metal -- PRINTING INK -- PRINTING MACHINE -- PRUSSIAN BLUE, and
PRUSSIATE OF POTASH -- PUMICE-STONE -- PUOZZOLANA -- PURPLE OF CASSIUS,
Gold purple -- PURPLE OF MOLLUSCA -- PURPURIC ACID -- PURPURINE --
PUTREFACTION and its prevention -- PYRITES -- PYRO-ACETIC SPIRIT --
PYROLIGNOUS ACID -- PYROLIGNOUS or PYROXILIC SPIRIT -- PYROMETER --
PYROPHORUS -- PYROTECHNY -- PYROXILINE

QUARTATION -- QUARTZ -- QUASSIA -- QUEEN’s WARE -- QUEEN’s YELLOW --
QUERCITRON -- QUICKLIME -- QUICKSILVER -- QUILL -- QUININA --
QUINTESSENCE

RAISINS -- RAPE-SEED -- RASP, MECHANICAL -- RATAFIA -- REALGAR --
RECTIFICATION -- RED LIQUOR -- REED -- REFINING OF GOLD AND SILVER --
REFRIGERATION OF WORTS, &c. -- REGULUS -- RESIN, KAURI or COWDEE --
RESINS -- RETORT -- REVERBERATORY FURNACE -- RHODIUM -- RIBBON
MANUFACTURE -- RICE -- RICE CLEANING -- RIFLE -- RINSING MACHINE --
ROCKETS -- ROLLING-MILL -- ROPE-MAKING -- ROSIN GAS -- ROSIN, or
COLOPHANY -- ROTTEN-STONE -- ROUGE -- RUBY -- RUM -- RUST -- RYE

SAFETY LAMP -- SAFFLOWER -- SAFFRON -- SAGO -- SAL AMMONIAC -- SAL
PRUNELLA -- SAL VOLATILE -- SALAMSTONE -- SALEP, or SALOUP -- SALICINE
-- SALT OF AMBER -- SALT OF LEMONS -- SALT OF SATURN -- SALT OF SODA --
SALT OF SORREL -- SALT OF TARTAR -- SALT OF VITRIOL -- SALT PERLATE --
SALT, EPSOM -- SALT, MICROCOSMIC -- SALT, SEA, or CULINARY; Chloride of
sodium -- SALT, SEDATIVE -- SALTPETRE -- SALTS -- SAND -- SANDAL or RED
SAUNDERS WOOD -- SANDARACH -- SAPAN WOOD -- SARD -- SATIN -- SATURATION
-- SCALIOLA -- SCARLET DYE -- SCHEELE’S GREEN -- SCHWEINFURTH GREEN --
SCOURING -- SEA WATER -- SEAL ENGRAVING -- SEALING-WAX -- SEGGAR, or
SAGGER -- SELENIUM -- SELTZER WATER -- SEPIA -- SEPTARIA -- SERPENTINE
-- SHAFT -- SHAGREEN -- SHALE, or SLATE-CLAY -- SHAMOY LEATHER --
SHEATHING OF SHIPS -- SHELLAC -- SIENITE -- SILICA and SILICON --
SILICATES -- SILICON -- SILK MANUFACTURE -- SILKWORM GUT -- SILVER --
SILVER LEAF -- SILVERING -- SIMILOR -- SINGEING OF WEBS -- SKIN -- SLAG
-- SLATES -- SMALL WARES -- SMALT -- SMELTING -- SOAP -- SOAPSTONE --
SODA-WATER -- SODA, Caustic soda -- SODA, CARBONATE OF -- SODIUM --
SOLDERING -- SOOT -- SORBIC ACID -- SOY -- SPECIFIC GRAVITY -- SPECULUM
METAL -- SPERMACETI -- SPIRIT OF AMMONIA -- SPIRIT OF WINE -- SPIRITS,
VINOUS -- SPONGE -- SPOON MANUFACTURE -- STAINED GLASS -- STAMPING OF
METALS -- STARCH -- STARCHING AND STEAM-DRYING APPARATUS -- STEAM --
STEARIC ACID, improperly called STEARINE -- STEARINE COLD PRESS --
STEATITE -- STEEL -- STEREOTYPE PRINTING -- STILL -- STOCKING
MANUFACTURE -- STONE -- STONE, ARTIFICIAL -- STONEWARE -- STORAX, STYRAX
-- STOVE -- STRASS -- STRAW-HAT MANUFACTURE -- STRETCHING MACHINE --
STRONTIA -- STRYCHNIA -- STUCCO -- SUBERIC ACID -- SUBLIMATE --
SUBLIMATION -- SUBSALT -- SUCCINIC ACID, Acid of Amber -- SUGAR -- SUGAR
OF LEAD -- SULPHATE OF ALUMINA AND POTASSA -- SULPHATE OF AMMONIA --
SULPHATE OF BARYTA -- SULPHATE OF COPPER -- SULPHATE OF IRON -- SULPHATE
OF LIME -- SULPHATE OF MAGNESIA, Epsom Salt -- SULPHATE OF MANGANESE --
SULPHATE OF MERCURY -- SULPHATE OF POTASSA -- SULPHATE OF SODA --
SULPHATE OF ZINC -- SULPHATES -- SULPHITES -- SULPHOSELS -- SULPHUR;
Brimstone -- SULPHURATION -- SULPHURETTED HYDROGEN -- SULPHURIC ACID,
Vitriolic Acid, or Oil of Vitriol -- SUMACH -- SWEEP-WASHER -- SYNTHESIS
-- SYRUP

TABBYING, or WATERING -- TACAMAHAC -- TAFFETY -- TAFIA -- TALC -- TALLOW
-- TALLOW, PINEY -- TAMPING -- TAN, or TANNIC ACID -- TANNING --
TANTALUM -- TAPESTRY -- TAPIOCA -- TAR -- TARRAS -- TARTAR -- TARTARIC
ACID -- TARTRATES -- TAWING -- TEA -- TEASEL -- TEETH -- TELLURIUM --
TERRA DI SIENA -- TERRA-COTTA -- TESTS -- TEXTILE FABRICS -- THENARD’S
BLUE, or COBALT BLUE -- THERMOMETER -- THERMOSTAT -- THIMBLE -- THORINA
-- THREAD MANUFACTURE -- TILES -- TILTING OF STEEL -- TIN -- TIN
MORDANTS -- TIN-GLASS -- TIN-PLATE -- TINCAL -- TINCTORIAL MATTER --
TINCTURE -- TITANIUM -- TOBACCO -- TOBACCO-PIPES -- TODDY -- TOLU --
TOMBAC -- TONKA BEAN -- TOPAZ -- TORTOISE-SHELL -- TOUCH-NEEDLES, and
TOUCH-STONE -- TOW -- TRAGACANTH, GUM -- TRAVERTINO -- TREACLE --
TRIPOLI -- TUFA, or TUF -- TULA METAL -- TUNGSTEN -- TURBITH MINERAL --
TURF -- TURKEY RED -- TURMERIC, Curcuma, Terra merita -- TURNSOLE --
TURPENTINE -- TURPENTINE, OIL OF -- TURQUOIS -- TUTENAG -- TYPE

ULTRAMARINE -- UMBER -- URANIUM -- URAO

VALONIA -- VANADIUM -- VANILLA -- VAPOUR -- VARNISH -- VEIN STONES, or
GANGUES -- VEINS -- VELLUM -- VELVET -- VENETIAN CHALK -- VENTILATION --
VENUS -- VERATRINE -- VERDIGRIS -- VERDITER, or BLUE VERDITER --
VERDITER, or BREMEN GREEN -- VERMICELLI -- VERMILLION, or Cinnabar --
VINEGAR MANUFACTORY, BY MALT -- VIOLET DYE -- VITRIFIABLE COLOURS --
VITRIOL

WACKE -- WADD -- WADDING -- WAFERS -- WALNUT HUSKS, or PEELS -- WARP --
WASH -- WASHING -- WATER-PROOF CLOTH -- WATERING OF STUFFS -- WATERS,
MINERAL -- WAX -- WAX, MINERAL, or Ozocerite, -- WEAVING -- WEFT -- WELD
-- WELDING -- WELLS, ARTESIAN -- WHALEBONE -- WHEAT -- WHEEL CARRIAGES
-- WHETSLATE -- WHEY -- WHISKEY -- WHITE LEAD -- WICK -- WINCING-MACHINE
-- WINE -- WINE-STONE -- WINE, FAMILY -- WIRE-DRAWING -- WOAD -- WOLFRAM
-- WOOD -- WOOF -- WOOLLEN MANUFACTURE -- WOOTZ -- WORT -- WOULFE’S
APPARATUS

XANTHINE

YEAST -- YELLOW DYE -- YELLOW, KING’S -- YTTRIA

ZAFFRE -- ZEDOARY -- ZIMOME -- ZINC -- ZIRCON -- ZIRCONIA




Transcriber’s Notes

General

This e-text follows the text of the original work, including
inconsistencies in spelling, hyphenation, capitalisation and typography.
In particular, the following have not been standardised or corrected
(except when mentioned below):

- the two types of fractions used (2-1/2 and 1-10th, for example);

- errors in calculations (for example, constituent parts that do not add
up to the total given);

- articles that are not in alphabetical order have not been moved (note
that I and J are considered to be equivalent, as in Jasper -- Icehouse
-- Jelly);

- missing reference letters/figures in illustrations;

- inconsistent numbering of sections and paragraphs (for example, there
may be a paragraph number 1, but no number 2 or further; there may be a
section number II, but no number I).

Some illustrations are missing from the original and are not referred to
in the text (Figs. 57, 372), others are provided in the original work,
but not discussed or described. Fig. 93 is not present in the original,
but is described in the text. The original has two illustrations
numbered 384; the second one (on page 464) has been renamed 384*.
Figures 496/497 and 498/499 are remarkably similar, as is their
description.


Remarks on the text

Fontanier and Fontanieu probably refer to the same person.

The text occasionally gives ohm and aime as inits of volume; these are
probably aams or ames (circa 30-36 imperial gallons).

There are several references to a table of elasticities of vapour; it is
not clear which table is meant.

Page 16, table: the temperature 164° stands out from the other
temperatures, and may be wrong (possibly error for 194°)

Page 16, The specific gravity of water at 60° being 1000, at 62° it is
99,981. This phrase contains at least one mistake: the intention might
be specific gravities 100 and 99·981, respectively (see also the table
following on page 21/22).

Page 19, table, first row, column 70°: 9991 does not fit in with the
other data, this is possibly an error for 9981.

Page 25, table, first row (17°): 44·9 does not fit with the other data;
this is possibly an error for 44·2; last row but one (24°): 693 does not
fit with the other data; possibly an error for 993.

Page 26, table, row 20°: the last value was partly illegible in the
original, this should probably be 68·4; row 22° the last decimal was
illegible in the original, this should probably be 67·7 or 67·8.

Page 29, Lausania inermis: probably Lawsonia inermis.

Page 41, reference to Gems, cutting of: the article Gems refers to the
article Lapidary for cutting of gems.

Page 46, Fig. 14, a plan of the same: Fig. 14 is a different side view.

Page 67, 1000 of a grain of silver: possibly an error for 1/1000 of a
grain of silver.

Page 99, reference to Saccharometer: there is no article Saccharometer;
the saccharometer is discussed in the article Beer only.

Page 111-112, description of location of elements relative to each
other: the author has reversed left and right.

Page 118, See Oil of Ben: there is no such article; the only reference
to Oil of Ben occurs on page 895 (table).

Page 150, teint, Germ.: probably error for teint, French.

Page 169, Fernambouc: the 16th century French name for Pernambuco.

Page 178, calculation: 315 loaves at 6d. give 7_l._ 17_s._ 6_d._, making
the clear profit 11_s._ 10_d._

Page 225, Chloride of Lime: there is no such article; chloride of lime
is discussed under Bleaching.

Page 249, reference to Mill: there is no such article; the article Sugar
has a part on mills.

Page 339, first table: the first two columns do not add up to the
sub-totals given; it is not clear whether this is due to errors in the
data or to miscalculation.

Page 358, Fig. 337 and accompanying text: text and illustration do not
seem to fit together, few of the parts mentioned appear in the figure.

Page 382, reference to Prussic Acid: the Dictionary does not have this
article.

Page 392, the year 173: the last digit was missing from the original,
and has been replaced with a tilde (173~). The 1858 enlarged edition
gives 1730 as the year.

Page 396, by of a lever: possibly a word is missing (by means of a lever
or similar).

Page 403, footnote [24]: 2198 should possibly read 1829.

Page 512, table Phosphorus: The two values in the last column are
incompatible: the first should be one half of the second.

Page 522, about 6-1/2 per cent. upon: possibly a word (such as
depending) is missing.

Page 564, second table: the totals do not always add up completely, and
the meaning of some of the data is unclear.

Page 605, Abrabanya: should possibly be Abrudbánya

Page 632, dyeing of horse-hair: this is described in the same, not the
next article.

Page 742, Bilin in Bohemia: also referred to as Billen and Billin.

Page 784, Houton-Libillardière: probably Jacques-Julien Houtou de La
Billardière.

Page 876, The carriage is then again by the rotation ...: there is a
verb missing from the text (advanced, moved forward, or similar).

Page 885, Nicaraca: possibly an error for Nicaragua.

Page 895, table, line 41: the specific gravity is likely to be a
misprint.

Page 897: strychia: possibly an error for strychnia.

Page 920, three separate sheets: the three knives will cut four sheets.

Page 1093, table: dr. in the column Cochineal may be an error for oz.

Page 1151, reference to page 1041: there is no related information on
this page.

Page 1204, arescence: possibly an error for acescence.

Page 1270, Then increase the gradually: a word is missing from the
original (possibly heat or temperature).


Changes and corrections made

Some missing punctuation has been added and obvious minor typographical
errors have been corrected silently.

Footnotes have been moved to under the paragraph etc. they refer to.

Illustrations have been moved to where they are first or most fully
described, they are therefore not always given in numerical order (the
original work does not always show them in numerical order either).
Illustration numbers have been added to illustrations that lacked a
number.

Multi-page tables have been changed to single tables; tables have been
re-arranged or split; some tables are presented here with legends or
table notes.

For the sake of consistency, the following changes have been made
throughout the text:

- All references to illustration numbers in the text have been
italicised (_Fig._ nnn etc.); reference letters in the text have been
standardised to italics (for lower case letters) and capitals (for upper
case letters).

- Apostrophes in French words have been closed with the following word
where necessary.

- All decimal points have been changed to mid-dots, commas and dashes
have been changed to mid-dots or vice versa where necessary.

- Accents on French words printed in capitals have been moved where
necessary (for example E' has been changed to É).

- The Alphabetical List of Articles has been added.

- The German ...saure in nouns has been standardised to ...säure.

- The author uses the single and double dashed pound sign; both are
represented here by the same symbol (£). All £/l. s. and d. (pound,
shilling, pence) have been italicised for consistency.


Other changes:

  Location               Original document      Changed to
  Page vi, table         201,773,872            204,773,872
  Page 14                olëine                 oleine as elsewhere
  Page 15                Brongniard             Brongniart
  Page 22, table,        ·70042                 ·00042
  row ·82
  ditto last line        ·100                   1·00
  Page 49                αηθραξ                   ανθραξ
  Page 57                _a a_                  A A as in illustration
  Page 69, Fig. 87       --                     letter c added
  Page 75                Baume                  Baumé as elsewhere
  Page 84                --                     2. added before Balsams
                                                without benzoic acid
  Page 92                intersticial           interstitial as else-
                                                where
  Page 109, second table 980                    0·980
  Page 112               the troughs u          the troughs n as in the
                                                illustration
  Page 122               Breislack              Breislak as elsewhere
  Page 144               sp. gr. 0837           sp. gr. 0·837
  ditto                  sheeps’ wool           sheep’s wool as else-
                                                where
  Page 167               fig. 165, between      fig. 163. Between
  Fig. 162               _c_                    _e_
  Page 171               tonne au noir          tonneau noir
  Page 178, calculation  7 17 5                 7 17 6
  ditto                  0 11 6-1/2             0 11 9-1/2
  Page 183               Fig. 170               Fig. 171
  ditto                  Fig. 171               Fig. 170
  Page 215               Elberfeldt             Elberfeld
  Page 220, Fig. 234     d                      d′ as in text
  Page 229               see ... page 224       see ... page 223
  Page 240               F′ G′                    F G as in illustration
  Page 243               tire                   tiré
  ditto                  _k_                    K
  Page 245               labiacæ                labiatæ
  Page 249               --                     quote marks added after
                                                ... for making candles.
  ditto                  undica                 indica
  Page 278               60·30 feet             69·39 feet
  Page 311               rhamnus fragula        rhamnus frangula
  Page 318               _Figs._ 297, 298.      _Figs._ 296, 298.
  Page 331               its bottom, C          its bottom, _c_
  Page 336               Gtakamite              Atakamite
  Page 345, Fig. 318     --                     ′s added as mentioned in
                                                text
  Page 356               pulley or whorl _g_    pulley or whorl _q_ as
                                                in drawing
  Page 372               5·463 lbs. of force    5463 lbs. of force
  Page 385               45 (or nearly so)      45° (or nearly so)
  Page 394               Münzstampeln           Münzstempeln
  Page 403               are constantly making  are constantly made
  Page 450               1·375                  137·5
  Page 464               --                     Fig. 384 renamed Fig.
                                                384*, (also reference to
                                                this illustration in
                                                text)
  Page 480, table header 3/4 to 174             3/4 to 1-1/4
  Page 481               Hamecons               Hameçons
  ditto                  Fishangeln             Fischangeln
  Page 499               _fig._ 524             _fig._ 452
  Page 510               Bernardiere            Bernardière
  ditto                  cachemire              cachemere as elsewhere
  Page 515, Peroxide     2F                     2Fe
  of iron
  Page 524, formula (1)  1·000,000              1,000,000
  Page 530, Fig. 480*    lower d                b
  Page 534               --                     Opening quotes added
                                                before conclusion nr. 1.
  Page 538, schematic    --                     2 inserted in second row
  Pillow Fustian
  Page 548, Fig. 482     --                     reference letter s added
  Page 552               30,000 feet of gas     30,000 cubic feet of gas
  Page 553               _fig._ 488             _fig._ 489 (second
                                                reference in text)
  Page 554, formula 7    )                      (
  Page 561               we have 100·4          we have 100 and 4
  Page 574, table        curly bracket embraces curly bracket embraces
                         lime and silica        silica only
  Page 580, Fig. 507     --                     illustration numbers
  and 508                                       interchanged to conform
                                                to text
  Page 594               (3 × 77·6) 232·8       (3 × 77·6) = 232·8
  Page 608               --                     closing quote mark added
                                                after ... 47 millions
                                                per annum.
  Page 618               Graufärbe              Graufarbe
  Page 645               Wohler                 Wöhler
  Page 650               a section of the       a section of the presser
                         pressure
  Page 658               _p_, small spiral      P, small spiral springs
                         springs                as in drawing
  Page 670               Liebeg                 Liebig
  Page 674               Elbeuf                 Elbœuf
  Page 684               Huttenberg             Hüttenberg
  Page 709               shachtofen             schachtofen
  Page 713               ruckstein              rückstein as elsewhere
  Page 740               as is shown in _fig._  as is shown in _fig._
                         621.                   622.
  Page 745               Himmelsfurst           Himmelsfürst
  ditto                  Beschertgluck          Beschertglück
  Page 746               Huelgoet               Huelgoët
  Page 747               gelena                 galena
  ditto                  Huelgöet               Huelgoët
  Page 748               Kongsburg              Kongsberg as elsewhere
  Page 749               _z_′ _z_′                _z z_ as in drawing
  Page 750               Z′ Z′                    _z z_ as in drawing
  Page 752               Poulläouen             Poullaouen as elsewhere
  Page 760               Vicenago               Viconago
  Page 774               Rudersdorf             Rüdersdorf
  Page 783               Farberröthe            Färberröthe
  Page 784               Societé                Société
  Page 785               Kuhlman                Kuhlmann
  Page 792               silk-works are reared  silk-worms are reared
  Page 793               magnesien              magnésien
  Page 805, Figs. 656    --                     primes added as
  and 657                                       described in text
  Page 814               Poullaounen            Pouallouen as elsewhere
  Page 818               K K′                    K′ K′′ as in
                                                illustration
  Page 822               Ehrenfriedensdorf      Ehrenfriedersdorf
  Page 828               mlydenum               molybdenum
  Page 829, table        ,                      · (2x)
  ditto                  --                     blank line inserted
                                                under Water
  ditto                  La Ferte-sous-Jouarre  La Ferté-sous-Jouarre
  Page 849               rothelie gende         rothe liegende
  ditto                  lumachello             lumachella
  Page 853               Breïtlingerwetter-     Breitlingerwetterschacht
                         schacht
  ditto                  _m_, _n_, _o_, _q_,    _m_, _n_, _o_, _q_,
                         R, _s_                 _r_, _s_
  Page 854/855 (table)   --                     table notes [a] through
                                                [d] were printed as
                                                vertical text in the
                                                original work
  Page 859               _t t_                  _t_ T as in illustration
  Page 868               oölite                 oolite
  ditto                  Puzzuolo               Puzzuoli
  Page 874               Braconot               Braconnot as elsewhere
  Page 889 (table)       93·024.                93,024
  Page 891               Stichstoffoxyd         Stickstoffoxyd
  Page 895               Hyociamus              Hyosciamus as elsewhere
  Page 897, table        --                     the original work has a
                                                mixture of plain text
                                                (olive oil and sperma-
                                                ceti) and table; this
                                                has been changed to a
                                                table
  Page 898               Wurtemburg             Wurtemberg as elsewhere
  Page 900               by passing into a      by passing into a slit-
                         slit-groove the verti- groove in the vertical
                         cal turning shaft      turning shaft
  Page 909               rosmarinus officialis  rosmarinus officinalis
  Page 922               _a_, _c_, _d_          _a_, _b_, _c_
  Page 929               --                     quote marks added after
                                                ... from the invention.
  Page 930, table        --                     2 added before Journey-
                                                men
  Page 931, table, first or 4 vats              3 or 4 vats
  line
  Page 933               (p. 967.)              (p. 936.)
  Page 944, table        grams                  grains
  header above No. I
  Page 989, Fig. 864     lower d                b
  Page 1000              rollers, _figs._       rollers, _figs._
                         885. 886.              886. 887.
  Page 1001              Descotil               Descotils
  Page 1002              Goro-Blagodatz         Goroblagodat as else-
                                                where
  Page 1029              Mintereau              Montereau as elsewhere
  Page 1056              Solfaterra             Solfetara
  Page 1080              --                     quote marks added after
                                                ... casualty from
                                                explosion.
  Page 1090              schlot-plan            schlot-pan
  Page 1074              _fig._ 50              _fig._ 950
  Page 1106              _Fig._ 796.            _Fig._ 976.
  Page 1127              _Fig._ 1011.           _Fig._ 1012.
  Page 1129              _Figs._ 1023. and      _Figs._ 1024. and 1025.
                         1026.
  Page 1137              Himmelfürst            Himmelsfürst
  Page 1175              --                     quote marks added after
                                                ... or of the alloys.
  Page 1185              Liquidamber            Liquidambar
                         styraciflua            styraciflua
  Page 1196              the feeder unites them the feeder unties them
  Page 1245              The portion B is to be The portion A is to be
                         washed again           washed again
  Page 1250,             --                     missing 0 in shillings-
  calculation                                   column added
  Page 1252              Poerner                Poërner
  Page 1253              Moiree                 Moirée
  Page 1281, table,      00·184                 0·0184
  column Carlsbad, row
  Fluoride of Calcium
  ditto column Seltzer,  00·185;                0·0185
  row Alumina
  ditto                  Pullna                 Püllna
  Page 1284              In his way             In this way
  Page 1332              _fig._ 1230            _fig._ 1231





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Mines, by Andrew Ure

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