CALORIC. The chemical name of the power or matter of heat.
CALORIFÈRE OF WATER. (_Calorifère d’eau_, Fr.; _Wasser-Heitzung_, Germ.)
In the _Dictionnaire Technologique_, vol. iv., published in 1823, we
find the following description of this apparatus, of late years so much
employed in Great Britain for heating conservatories, &c. by hot water
circulating in pipes:--
[Illustration: 252]
“This mode of heating is analogous to that by stove pipes: it is
effected by the circulation of water, which, like air, is a bad
conductor, but may serve as a carrier of caloric by its mobility. We may
readily form an idea of the apparatus which has been employed for this
purpose. We adapt to the upper part of either a close kettle, or of an
ordinary cylindric boiler A, _fig._ 252, a tube B, which rises to a
certain height, then descends, making several sinuosities with a gentle
slope till it reaches the level of the bottom of the boiler, to whose
lowest part, as that which is least heated, it is fitted at C. At the
highest point of the tube F we adapt a vertical pipe, destined to serve
as an outlet to the steam which may be formed if the temperature be too
much raised: it serves also for the escape of the air expelled from the
water by the heat; and it permits the boiler to be replenished from time
to time as the water is dissipated by evaporation; lastly, it is a tube
of safety.
“The apparatus being thus arranged, and all the tubes as well as the
boiler filled with water, if we kindle fire in the grate D, the first
portions of water heated, having become specifically lighter, will tend
to rise: they will actually mount into the upper part of the boiler,
and, of course, enter the tube B F: at the same time an equivalent
quantity of water will re-enter the boiler by the other extremity C of
the tube. We perceive that these simultaneous movements will determine a
circulation in the whole mass of the liquid, which will continue as long
as heat is generated in the fire-place; and if we suppose that the
tubes, throughout their different windings, are applied against the
walls of a chamber, or a stove-room, the air will get warmed by contact
with the hot surfaces; and we may accelerate the warming by multiplying
these contacts in the mode indicated.
“This _calorifère_ cannot be employed so usefully as those with heated
air, when it is wished to heat large apartments. In fact, the passage of
heat through metallic plates is in the ratio of the difference of
temperature and quantity of the heating surfaces. In the present case,
the temperature of the water, without pressure, in the tubes, must be
always under 100° C. (212° F.), even in those points where it is most
heated, and less still in all the other points, while the temperature of
the flues in _air stoves_, heated directly by the products of
combustion, may be greatly higher. In these stoves, also, the pipes may
without inconvenience have a large diameter, and present, consequently,
a large heating surface; whereas, with the water _calorifère_, the
pressure exercised by the liquid upon the sides of the tubes being in
the ratio of the surfaces, we are obliged, in order to avoid too great
pressure, to employ a multitude of small tubes, which is expensive.
Lastly, if the hot-water circulation is to be carried high, as may be
often necessary in lofty buildings, the pressure resulting from the
great elevation would call for proportional thickness in the tubes and
the boiler: for these reasons, and others which we shall state in
treating of heating by steam, it appears that water cannot be
advantageously substituted for air or steam in the applications above
stated; yet this mode of heating presents very decided advantages where
it is useful to raise the temperature a small number of degrees in a
uniform manner.” See INCUBATION, ARTIFICIAL.
“M. Bonnemain applied, with much success, these ingenious processes of
heating by the circulation of water, to maintain a very equal
temperature in hot-houses (_serres-chaudes_), in stoves adapted to
artificial incubation, and in preserving or quickening vegetation within
hot-houses, or outside of their walls, during seasons unpropitious to
horticulture.
“Since the capacity of water for heat is very great, if the mass of it
in a circulation-apparatus be very considerable, and the circulation be
accelerated by proper arrangements, as by cooling the descending tube
exterior to the stove-room, we may easily obtain by such means a
moderately high and uniform temperature, provided the heat generated in
the fire-place be tolerably regular. We may easily secure this essential
point by the aid of the _fire-regulator_, an instrument invented by M.
Bonnemain, and which is described under the article INCUBATION, because
there its use seems to be indispensable.”
From the above quotation, and, more especially, from the evidence
adduced in the article INCUBATION, we see how little claim the Marquis
de Chabannes, or any of his followers, can have to invention in their
arrangements for heating apartments by the calorific motions of the
particles of water, enclosed in pipes of any kind.
CAMBRIC. (_Batiste_, Fr.; _Kammertuch_, Germ.) A sort of very fine and
rather thin linen fabric, first made at Cambray. An excellent imitation
of this fabric is made in Lancashire, woven from fine cotton yarn hard
twisted. Linen cambric of a good quality is also now manufactured in the
United Kingdom from power-spun flax.
CAMLET OR CAMBLET. A light stuff, much used for female apparel. It is
made of long wool hard spun, sometimes mixed in the loom with cotton or
linen yarn.
CAMPHOR, or CAMPHIRE. This immediate product of vegetation was known to
the Arabs under the names of _kamphur_ and _kaphur_, whence the Greek
and Latin name _camphora_. It is found in a great many plants, and is
secreted, in purity, by several laurels: it occurs combined with the
essential oils of many of the _labiatæ_; but it is extracted, for
manufacturing purposes only, from the _Laurus camphora_, which abounds
in China and Japan, as well as from a tree which grows in Sumatra and
Borneo, called, in the country, _Kapour barros_, from the name of the
place where it is most common. The camphor exists, ready formed, in
these vegetables, between the wood and the bark; but it does not exude
spontaneously. On cleaving the tree _Laurus sumatrensis_, masses of pure
camphor are found in the pith.
The wood of the laurus is cut into small pieces, and put, with plenty of
water, into large iron boilers, which are covered with an earthen
capital or dome, lined within with rice straw. As the water boils, the
camphor rises with the steam, and attaches itself as a sublimate to the
stalks, under the form of granulations of a grey colour. In this state
it is picked off the straw, and packed up for exportation to Europe.
Formerly Venice held the monopoly of refining camphor, but now France,
England, Holland, and Germany refine it for their own markets. All the
purifying processes proceed on the principle that camphor is volatile at
the temperature of 400° F. The substance is mixed, as intimately as
possible, with 2 per cent. of quicklime, and the mixture is introduced
into a large bottle made of thin uniform glass, sunk in a sand bath. The
fire is slowly raised till the whole vessel becomes heated, and then its
upper part is gradually laid bare in proportion as the sublimation goes
on. Much attention and experience are required to make this operation
succeed. If the temperature be raised too slowly, the neck of the bottle
might be filled with camphor before the heat had acquired the proper
subliming pitch; and, if too quickly, the whole contents might be
exploded. If the operation be carried on languidly, and the heat of the
upper part of the bottle be somewhat under the melting point of camphor,
that is to say, a little under 350° F., the condensed camphor would be
snowy, and not sufficiently compact and transparent to be saleable.
Occasionally, sudden alternations of temperature cause little jets to be
thrown up out of the liquid camphor at the bottom upon the cake formed
above, which soil it, and render its re-sublimation necessary.
If, to the mixture of 100 parts of crude camphor and 2 of quicklime, 2
parts of bone-black, in fine powder, be added, the small quantity of
colouring matter in the camphor will be retained at the bottom, and
whiter cakes will be produced. A spiral slip of platina foil immersed in
the liquid may tend to equalise its ebullition.
By exposing some volatile oils to spontaneous evaporation, at the heat
of about 70° F., Proust obtained a residuum of camphor; from oil of
lavender, 25 per cent. of its weight; from oil of sage, 12-1/2; from oil
of marjoram, 10.
Refined camphor is a white translucid solid, possessing a peculiar taste
and smell. It may be obtained, from the slow cooling of its alcoholic
solution, in octahedral crystals. It may be scratched by the nail, is
very flexible, and can be reduced into powder merely by mixing it with a
few drops of alcohol. Its specific gravity varies from 0·985 to 0·996.
Mixed and distilled with six times its weight of clay, it is decomposed,
and yields a golden yellow aromatic oil, which has a flavour analogous
to that of a mixture of thyme and rosemary; along with a small quantity
of acidulous water tinged with that oil, charcoal remains in the retort.
In the air, camphor takes fire on contact of an ignited body, and burns
all away with a bright fuliginous flame.
Camphor is little soluble in water; one part being capable of
communicating smell and taste to 1000 of the fluid. 100 parts of
alcohol, spec. grav. 0·806, dissolve 120 parts of camphor, at ordinary
temperatures. It is separated, in a pulverulent state, by water. Ether
and oils, both expressed and volatile, also dissolve it.
When distilled with eight parts of aquafortis, camphor is converted into
camphoric acid. Camphor absorbs 144 times its volume of muriatic acid
gas, and is transformed into a colourless transparent liquid, which
becomes solid in the air, because the acid attracts humidity, which
precipitates the camphor. One part of strong acetic acid dissolves two
parts of camphor. By my analysis, camphor consists of 77·38 carbon,
11·14 hydrogen, and 11·48 oxygen. Berzelius’s numbers are certainly
erroneous.
CAMWOOD. An article imported from Sierra Leone, which seems to possess
similar dyeing powers with Brazil or Nicaragua wood.
CANDLE. (_Chandelle_, Fr.; _Kerze_, _Licht_, Germ.) I shall first
briefly describe the ordinary manufacture of candles. They are either
dipped or moulded. But the first part of the process is the sorting of
the tallow. Mutton suet with a proportion of ox-tallow is selected for
mould candles, because it gives them gloss and consistence. Coarser
tallow is reserved for the dipped candles. After being sorted, it is cut
into small pieces, preparatory to being melted or _rendered_; and the
sooner this is done after the fat is taken from the carcase the better,
because the fibrous and fleshy matters mixed with it promote its
putrefaction. Tallow is too commonly melted by a naked fire applied to
the bottom of the vessel, whereas it should be done either in a cold set
pan, where the flame plays only round the sides a little way above the
bottom, or in a steam-cased pan. After being fused a considerable time,
the membranous matters collect at the surface, constituting the
_cracklings_ used sometimes for feeding dogs, after the fat has been
squeezed out of it by a press. The liquid tallow is strained through a
sieve into another copper, where it is treated with water at a boiling
temperature in order to wash it. After a while, when the foul water has
settled to the bottom, the purified tallow is lifted out, by means of
tinned iron buckets, into tubs of a moderate size, where it concretes,
and is ready for use.
It is a remarkable circumstance, that the wicks for the best candles are
still cotton rovings imported from Turkey, notwithstanding the vast
extension and perfection of cotton-spinning in this country. Four or
more of these Turkey skeins, according to the intended thickness of the
wick, are wound off at once into bottoms or clues, and afterwards cut by
a simple machine into lengths corresponding to those of the candles to
be made. Mr. Colebank obtained a patent, in June, 1822, for a machine
for cutting, twisting, and spreading wicks, which, though convenient,
does not seem to have come into general use. The operations are
performed upon a series of threads at once. The apparatus is placed in a
box, in front of which the operator sits. A reel extends across the box,
at the hinder part, upon which the cotton threads have been previously
wound: from this reel they are drawn off in proper lengths, doubled, and
cut by an ingenious mechanism. By dipping the wicks into the melted
tallow, rubbing them between the palms of the hands, and allowing the
tallow which adheres to harden, they may be arranged with facility upon
the broaches for the purpose of dipping. The dipping room is furnished
with a boiler for melting the tallow, the dipping mould, or cistern, and
a large wheel for supporting the broaches. From the ceiling of the
workshop a long balance-shaped beam is suspended, to one end of which a
wooden frame is attached for holding the broaches with the wicks
arranged at proper distances. The opposite arm is loaded with a weight
to counterbalance the wooden frame, and to enable the workman to
ascertain the proper size of the candles. The end of the lever which
supports the frame is placed immediately above the dipping cistern; and
the whole machine is so balanced that, by a gentle pressure of the hand,
the wicks are let down into the melted tallow as often as may be
required.
[Illustration: 253]
The following convenient apparatus for dipping candles has been long in
use at Edinburgh. In the centre of the dipping-room a strong upright
post A A, _fig._ 253., is erected, with turning iron pivots at its two
ends. Near its middle, six mortises are cut at small distances from one
another, into each of which is inserted a long bar of wood B B, which
moves vertically upon an iron pin, also passing through the middle of
the shaft. The whole presents the appearance of a large horizontal wheel
with twelve arms. A complete view of two of them only is given in the
figure. From the extremity of each arm is suspended a frame, or port, as
the workmen call it, containing 6 rods, on each of which are hung 18
wicks, making the whole number of wicks upon the wheel 1296. The
machine, though apparently heavy, turns round by the smallest effort of
the workman; and each port, as it comes in succession over the
dipping-mould, is gently pressed downwards, by which means the wicks are
regularly immersed in melted tallow. As the arms of the lever are all of
the same length, and as each is loaded with nearly the same weight, it
is obvious that they will all naturally assume a horizontal position. In
order, however, to prevent any oscillation of the machine in turning
round, the levers are kept in a horizontal position by means of small
chains _a a_, one end of which is fixed to the top of the upright shaft,
and the other terminates in a small square piece of wood _b_, which
exactly fills the notch _c_ in the lever. As one end of the levers must
be depressed at each dip, the square piece of wood is thrown out of the
notch by the workman pressing down the handle D, which communicates with
the small lever _e_, inserted into a groove in the bar B. In order that
the square piece of wood, fixed in one extremity of the chain, may
recover its position upon the workman’s raising the port, a small cord
is attached to it, which passes over a pulley inserted in a groove near
_c_, and communicates with another pulley and weight, which draws it
forward to the notch. In this way the operation of dipping may be
conducted by a single workman with perfect ease and regularity, and even
dispatch. No time is lost, and no unnecessary labour expended, in
removing the ports after each dip; and, besides, the process of cooling
is much accelerated by the candles being kept in constant motion through
the air. The number of revolutions which the wheel must make, in order
to complete one operation, must obviously depend upon the state of the
weather and the size of the candles; but it is said that, in moderately
cold weather, not more than two hours are necessary for a single person
to finish one wheel of candles of a common size. Upon the supposition,
therefore, that six wheels are completed in one day, no less a number
than 7776 candles will be manufactured in that space of time by one
workman.
I shall next describe the process of moulding, which, if possible, is
even less complicated in its details than that of dipping. The moulds
are made of some metallic substance, usually pewter, and consist of two
parts. The shaft or great body of the mould is a hollow cylinder, finely
polished in the inside, and open at both extremities. The top of the
mould is a small metallic cup, having a moulding within-side, and a hole
to admit the wick. The two parts are soldered together, and when united,
as will readily be imagined, have the shape of a moulded candle. A third
piece, called the foot, is sometimes added; it is a kind of small
funnel, through which the liquid tallow runs into the mould, and, being
screwed to the opposite extremity of the shaft, is removable at
pleasure. This additional piece may certainly be useful in very mild
weather; since, by removing it, the candles may be drawn more easily
from the moulds; but, in general, it may be dispensed with.
Eight or twelve of these moulds, according to their size, are fixed in a
frame, which bears a great resemblance to a wooden stool, the upper
surface of which forms a kind of trough. The top of the moulds points
downwards, and the other extremity, which is open, is inserted into the
bottom trough or top of the stool, and made quite level with its upper
surface. In order to introduce the wicks into the mould, the workman
lays the frame upon its side on an adjoining table, and holding in his
left hand a quantity of wicks, previously cut to the proper length, he
introduces into the mould a long wire with a hooked point. As soon as
the hook of the wire appears through the hole in the top of the mould,
he attaches to it the looped end of the wick, and, immediately drawing
back the wire, carries the wick along with it. In this manner each mould
in succession is furnished with a wick. Another workman now follows, and
passes a small wire through the loop of each wick. This wire is
obviously intended to keep the wick stretched, and to prevent it from
falling back into the mould upon the frame being placed in the proper
position for filling. The frame is then handed to the person that fills
the moulds, who previously arranges the small wires in such a manner
that each wick may be exactly in the middle of the mould.
The moulds are filled by running tallow into each of them, or into the
trough, from a cistern furnished with a cock, and which is regularly
supplied with tallow of the proper temperature from an adjoining boiler.
When the workman observes that the moulds are nearly half filled he
turns the cock, and, laying hold of that portion of the wick which hangs
out of the mould, pulls it tight, and thus prevents any curling of the
wick, which might injure the candles: he then opens the cock, and
completes the process of filling. The frame is now set aside to cool;
and when the tallow has acquired a proper consistence, which the workman
easily discovers by a snapping noise emitted by the candles upon
pressing his thumb against the bottom of the moulds, he first withdraws
the small wires which kept the wicks tense, and then, scraping off the
loose tallow from the top of the frame with a small wooden spade, he
introduces a bodkin into the loop of the wick, and thus draws each
candle in succession from its mould. The candles are now laid upon a
table for the inspection of the exciseman, and afterwards removed to the
storehouse. Previous to storing them up, some candle-makers bleach their
candles, by exposing them to the air and dews for several days. This
additional labour can be necessary only when the dealer is obliged to
have early sales; for if the candles are kept for some months, as they
ought to be, before they are brought to market, they become sufficiently
whitened by age.
_Wax candles._--Next to tallow, the substance most employed in the
manufacture of candles is wax. Wax candles are made either by the hand
or with a ladle. In the former case, the wax, being kept soft in hot
water, is applied bit by bit to the wick, which is hung from a hook in
the wall; in the latter, the wicks are hung round an iron circle, placed
immediately over a large copper-tinned basin full of melted wax, which
is poured upon their tops, one after another, by means of a large ladle.
When the candles have by either process acquired the proper size, they
are taken from the hooks, and rolled upon a table, usually of
walnut-tree, with a long square instrument of box, smooth at the bottom.
A few years ago I made a set of experiments upon the relative
intensities of light, and duration of different candles, the results of
which are contained in the following table.
+----------+-----------+-------+--------+-------+-------+---------+
| | | |Consump-|Propor-| | |
| Number | Duration | Weight|tion per| tion | Econ- |Candles |
| in a | of a | in |hour in | of | omy of|equal one|
| pound. | candle. |grains.|grains. |light. | light.|Argand. |
+----------+-----------+-------+--------+-------+-------+---------+
| |_h._ _m._ | | | | | |
|10 mould | 5 9 | 682 | 132 | 12-1/4| 68 | 5·7 |
|10 dipped | 4 36 | 672 | 150 | 13 | 65-1/2| 5·25 |
| 8 mould | 6 31 | 856 | 132 | 10-1/2| 59-1/2| 6·6 |
| 6 ditto | 7 2-1/2| 1160 | 163 | 14-2/3| 66 | 5·0 |
| 4 ditto | 9 3·6 | 1707 | 186 | 20-1/4| 80 | 3·5 |
|Argand oil| -- | -- | 512 | 69·4 |100 | |
|flame | | | | | | |
+----------+-----------+-------+--------+-------+-------+---------+
A Scotch mutchkin, or 1/8 of a gallon of good seal oil, weighs 6010 gr.,
or 13-1/10 oz., avoirdupois, and lasts in a bright Argand lamp 11 hours
44 minutes. The weight of oil it consumes per hour is equal to 4 times
the weight of tallow in candles 8 to the pound, and 1/7 the weight of
tallow in candles 6 to the pound. But, its light being equal to that of
5 of the latter candles, it appears from the above table that 2 pounds
weight of oil, value 9_d._ in an Argand, are equivalent in illuminating
power to 3 pounds of tallow candles, which cost about two shillings. The
larger the flame in the above candles the greater the economy of light.
In June, 1825, M. Gay Lussac obtained a patent in England for making
candles from _margaric and stearic acids_, improperly called _stearine_,
by converting tallow into the above fat acids by the following
process:--Tallow consists, by Chevreul’s researches, of stearine, a
solid fat, and elaine, a liquid fat; the former being in much the larger
proportion. When tallow is treated with an alkaline body, such as
potash, soda, or lime, it is saponified; that is, its stearine and
elaine become respectively stearic and elaic acids, and, as such, form
compounds with these bases. When by the action of an acid, such as the
sulphuric or muriatic, these combinations are decomposed, the fats
reappear in the altered form of stearic and elaic acids; the former body
being harder than tallow, and of a texture, somewhat like spermaceti,
the latter body being fluid, like oil. “The decomposition of the soap
should be made,” says the patentee, “in a large quantity of water, kept
well stirred during the operation, and warmed by steam introduced in any
convenient way. When the mixture has been allowed to stand, the acid of
the tallow or fat will rise to the surface, and the water being drawn
off will carry the alkaline or saline matters with it; but, if the acids
of the tallow should retain any portion of the salts, fresh water may
be thrown upon it, and the whole well agitated, until the acids have
become perfectly free from the alkaline matters; and, when allowed to
cool, the acids will be formed into a solid mass. This mass is now to be
submitted to considerable pressure in such an apparatus as is employed
in expressing oil from seeds; when the liquid acid will run off in the
form of a substance resembling oil, leaving a solid matter, similar, in
every respect, to spermaceti, which is fit for making candles.”
The wick to be used in the manufacture of these improved candles, and
which forms one of the features of this invention, is to be made of
cotton yarn, twisted rather hard, and laid in the same manner as wire is
sometimes coiled round the bass strings of musical instruments. For this
purpose, straight rods or wires are to be procured, of suitable lengths
and diameters, according to the intended size of the candles about to be
made; and these wires, having been covered with cotton coiled round
them, as described, are to be inserted in the candle moulds as the
common wicks are; and when the candle is made, and perfectly hard, the
wire is to be withdrawn, leaving a hollow cylindrical aperture entirely
through the middle of the candle. See STEARINE.
CANE-MILL. See MILL and SUGAR.
CANNON. For the composition of these implements of destruction, see
BRONZE.
CANVASS (_Canevas_, Fr.; _Segeltuch_, Germ.) It has been found that
sails of ships made with the selvages and seams of the canvass running
down parallel to their edges, are very apt to bag, and become torn in
the middle, from the strain to which they are subjected by the pressure
of the wind. To obviate this inconvenience, a mode of making sails, with
the seams and selvages running diagonally, was proposed by Admiral
Brooking, and a patent granted to him for the same on 4th of September,
1828. The invention of Messrs. Ramsay and Orr, which we are about to
describe, has a similar object, viz., that of giving additional strength
to sails by a peculiar manner of weaving the canvass of which they are
made.
The improvement proposed under their patent of March, 1830, consists in
weaving the canvass with diagonal threads; that is, placing the weft
yarn, or shoot, in weaving, at an oblique angle to the warp yarns,
instead of making the decussation of the warp, or weft threads, or
yarns, at right angles to each other, as in the ordinary mode of
weaving.
To accomplish this object the loom must be peculiarly constructed; that
is, its warp and work beams must stand at an oblique angle with the
sides of the loom, and the batten and slay must be hung in a peculiar
manner, in order to beat up the weft, or shoot, in lines ranging
diagonally with the warp. No drawing is shown of the method by which
this arrangement of the loom is to be made, but it is presumed that any
weaver would know how to accomplish it: the invention consisting solely
in producing sail cloth with the threads, or yarns, of the weft ranging
diagonally at any desired angle with the direction of the warp thread.
CAOUTCHOUC, GUM-ELASTIC, OR INDIAN-RUBBER, (_Federharz_, Germ.) occurs
as a milky juice in several plants, such as the _siphonia cahuca_,
called also _hevea guianensis_, _cautschuc_, _jatropha elastica_,
_castilleja elastica_, _cecropia pellata_, _ficus religiosa_ and
_indica_, _urceolaria elastica_, &c. It is, however, extracted chiefly
from the first plant, which grows in South America and Java. The tree
has incisions made into it through the bark in many places, and it
discharges the milky juice, which is spread upon clay moulds, and dried
in the sun, or with the smoke of a fire, which blackens it.
The juice itself has been of late years imported. It is of a pale yellow
colour, and has the consistence of cream. It becomes covered in the
bottles containing it with a pellicle of concrete caoutchouc. Its spec.
grav. is 1·012. When it is dried it loses 55 per cent. of its weight:
the residuary 45 is elastic gum. When the juice is heated it immediately
coagulates, in virtue of its albumen, and the elastic gum rises to the
surface. It mixes with water in any proportion; and, when thus diluted,
it coagulates with heat and alcohol as before.
The specific gravity of caoutchouc is 0·925, and it is not permanently
increased by any degree of pressure. By cold or long quiescence it
becomes hard and stiff. When the milky juice has become once coherent,
no means hitherto known can restore it to the emulsive state. By long
boiling in water it softens, swells, and becomes more readily soluble in
its peculiar menstrua; but when exposed to the air it speedily resumes
its pristine consistence and volume. It is quite insoluble in alcohol;
but in ether, deprived of alcohol by washing with water, it readily
dissolves, and affords a colourless solution. When the ether is
evaporated, the caoutchouc becomes again solid, but is somewhat clammy
for a while. When treated with hot naphtha, distilled from native
petroleum, or from coal tar, it swells to 30 times its former bulk; and
if then triturated with a pestle, and pressed through a sieve, it
affords a homogeneous varnish, which being applied by a flat edge of
metal or wood to cloth, prepares it for forming the patent water-proof
cloth of Mackintosh. Two surfaces of cloth, to which several coats of
the above varnish have been applied, are, when partially dried, brought
evenly in contact, and then passed between rollers, in order to condense
and smooth them together. This double cloth is afterwards suspended in
a stove-room to dry, and to discharge the disagreeable odour of the
naphtha.
Caoutchouc dissolves in the fixed oils, such as linseed oil, but the
varnish has not the property of becoming concrete upon exposure to air.
It has been lately asserted that caoutchouc is soluble in the oils of
lavender and sassafras.
It melts at 248° F., and stands afterwards a much higher heat without
undergoing any further change. When the melted caoutchouc is exposed to
the air, it becomes hard on the surface in the course of a year. When
kindled it burns with a bright flame and a great deal of smoke.
Neither chlorine, sulphurous acid gas, muriatic acid gas, ammonia, nor
fluosilicic acid gas, affect it, whence it forms very valuable flexible
tubes for pneumatic chemistry. Cold sulphuric acid does not readily
decompose it, nor does nitric acid, unless it be somewhat strong. The
strongest caustic potash lye does not dissolve it even at a boiling
heat.
Caoutchouc, according to my experiments, which have been confirmed by
those of Mr. Faraday, contains no oxygen, as almost all other solid
vegetable products do, but is a mere compound of carbon and hydrogen, in
the proportion, by my results, of 90 carbon to 10 hydrogen, being three
atoms of the former to two of the latter. Mr. Faraday obtained only 87·2
carbon, from which I would infer that some of the carbon, which in this
substance is difficult to acidify by peroxide of copper, had escaped its
action. It is obvious that too little carbonic acid gas may be obtained,
but certainly not more than corresponds to the carbon in the body. No
carbon can be created in the process of ultimate analysis by pure
peroxide of copper such as I employed; and I repeated the ignition after
attrition of the mixture used in the experiment. Melted caoutchouc forms
a very excellent chemical lute, as it adheres very readily to glass
vessels, and withstands the corrosive action of acid vapours. This
substance is much used for effacing the traces of plumbago pencils,
whence it derived the name of Indian-rubber. It has been lately employed
very extensively for making elastic bands or braces. The caoutchouc
bottles are skilfully cut into long spiral slips, which are stretched,
and kept extended till nearly deprived of their elasticity, and till
they form a thread of moderate fineness. This thread is put into a braid
machine, and covered with a sheath of cotton, silk, linen, or worsted.
The clothed caoutchouc is then laid as warp in a loom, and woven into an
elegant riband. When woven, it is exposed, upon a table to the action of
a hot smoothing iron, which restoring to the caoutchouc all its
primitive elasticity, the riband retracts considerably in length, and
the braiding corrugates equally upon the caoutchouc cores. Such bands
possess a remarkable elasticity, combined with any desired degree of
softness. Sometimes cloth is made of these braided strands of caoutchouc
used both as warp and as weft, which is therefore elastic in all
directions. When a light fabric is required, the strands of caoutchouc,
either naked or braided, are alternated with common warp yarns. For this
mixed fabric a patent has been obtained. The original manufacturer of
these elastic webs is a major in the Austrian service, who has erected a
great factory for them at St. Denys, near Paris. See ELASTIC BANDS.
[Illustration: 254]
Mr. William Henry Barnard, in the course of some experiments upon the
impregnation of ropes with caoutchouc, at the factory of Messrs. Enderby
at Greenwich, discovered that when this substance was exposed to a heat
of about 600° F. it resolved itself into a vapour, which, by proper
refrigeratory methods, was condensable into a liquid possessing very
remarkable properties, to which the name caoutchoucine has been given.
For this invention “of a solvent not hitherto used in the arts” Mr.
Barnard obtained a patent, in August, 1833. His process for preparing it
is described in his specification as follows:--I take a mass of the said
caoutchouc, or Indian rubber, as imported, and having cut it into small
lumps, containing about two cubic inches each (which I prefer), I throw
these lumps into a cast-iron still (which I find adapted for the
purpose, and a diagram of which is annexed to, and forms part of, this
my specification), with a worm attached; _fig._ 254., A is the still, B
the cover ground to a metallic fit, to admit of a thermometer to take
the temperature; C the fire-place, D the ash-pit, E the worm-tub and
worm, F the brick-work of the still, G a roller and carriage, in
conjunction with a crane, or other means, to raise the cover to take out
the residue, and to charge the same; H the chain.
I then apply heat to the still in the usual manner, which heat is
increased until the thermometer ranges at 600 degrees of Fahrenheit, or
thereabouts. And, as the thermometer ranges progressively upwards to 600
degrees of Fahrenheit, a dark-coloured oil or liquid is distilled over,
which I claim as my said invention, such liquid being a solvent of
caoutchouc, and other resinous and oleaginous substances. When the
thermometer reaches 600 degrees, or thereabouts, nothing is left in the
still but dirt and charcoal.
I have found the operation of distillation to be facilitated by the
addition of a portion of this oil, either previous or subsequent to
rectification, as hereinafter mentioned, in the proportion of one third
of oil to two thirds of caoutchouc.
I afterwards subject the dark-coloured liquid thus distilled to the
ordinary process of rectification, and thereby obtain fluids varying in
specific gravity, of which the lightest hitherto has not been under 670,
taking distilled water at 1000, which fluids I also claim as my said
invention.
At each rectification the colour of the liquid becomes more bright and
transparent, until at the specific gravity of 680, or thereabouts, it is
colourless and highly volatile.
In the process of rectification (for the purpose of obtaining a larger
product of the oil colourless) I put about one third of water into the
still. In each and every state the liquid is a solvent of caoutchouc,
and several resinous and oleaginous substances, and also of other
substances (such as copal), in combination with very strong alcohol.
Having experienced much difficulty in removing the dirt which adheres to
the bottom of the still, I throw into the still, lead and tin in a state
of alloy (commonly called solder), to the depth of about half an inch,
and, as this becomes fused, the dirt which lies on the surface of it is
more easily removed.
Objections have been made to the smell of this liquid:--I have found
such smell removed by mixing and shaking up the liquid with
nitro-muriatic acid, or chlorine, in the proportion of a quarter of a
pint of the acid (of the usual commercial strength) to a gallon of the
liquid.
The discovery of the chemical solvent, which forms the subject of the
patent above described, has excited considerable interest in the
philosophic world, not only from its probable usefulness as a new
article of commerce, but also from two very extraordinary
characteristics which it is found to possess, viz., that, in a liquid
state, it has less specific gravity than any other liquid known to
chemists, being considerably lighter than sulphuric ether, and, in a
state of vapour, is heavier than the most ponderous of the gases.
Its elementary constituents are,
Carbon 6·812 8 proportions.
Hydrogen 1·000 7 ditto.
This new material (when mixed with alcohol) is a solvent of all the
resins and particularly of copal, which it dissolves, without artificial
heat, at the ordinary temperature of the atmosphere; a property
possessed by no other solvent known; and hence it is peculiarly useful
for making varnishes in general. It also mixes readily with oils, and
will be found to be a valuable and cheap menstruum for liquefying
oil-paints; and without in the slightest degree affecting the most
delicate colours, will, from its ready evaporation, cause the paint to
dry almost instantly.
Cocoa-nut oil, at the common temperature of the atmosphere, always
assumes a concrete form; but a portion of this caoutchoucine mixed with
it will cause the oil to become fluid, and to retain sufficient fluidity
to burn in a common lamp with extraordinary brilliancy.
Caoutchoucine is extremely volatile; and yet its vapour is so
exceedingly heavy, that it may be poured, without the liquor, from one
vessel into another like water.
CAPERS. The caper is a small prickly shrub, cultivated in Spain, Italy,
and the southern provinces of France. The flowers are large roses of a
pretty appearance, but the flower buds alone are the objects of this
cultivation.
They are plucked before they open, and thrown into strong vinegar
slightly salted, where they are pickled. The crop of each day is added
to the same vinegar tub, so that in the course of the six months during
which the caper shrub flowers, the vessel gets filled, and is sold to
persons who sort the capers, (the smallest being most valued) by means
of copper sieves. This metal is attacked by the acid, wherefrom the
fruit acquires a green colour, much admired by _ignorant connoisseurs_.
The capers, as found in the French market, are distinguished into five
sorts; the _non-pareille_, the _capucine_, the _capote_, the _second_,
and the _third_; this being the decreasing order of their quality, which
depends upon the strength of the vinegar used in pickling them, as also
the size and colour of the buds.
The caper shrub grows in the driest situations, even upon walls, and
does not disdain any soil; but it loves a hot and sheltered exposure. It
is multiplied by grafts made in autumn, as also by slips of the roots
taken off in spring.
CAPSTAN. (_Cabestan_, Fr.; _Spille_, Germ.) A machine whereon the cable
is wound successively in weighing the anchor of a vessel. It is a
species of wheel and axle; the axle being vertical, and pierced with
holes near its top for the insertion of the ends of horizontal levers,
called handspikes, which represent the wheel. These are turned by the
force of men moving in a circle. The power applied to the lever is to
the resistance to be overcome, (the weight of the anchor, for example,)
when the forces are in equilibrio, as the radius of the cylinder round
which the cable is coiled is to the circumference described by the
power.
It is manifest that the radius of the axle must be augmented in this
computation by half the diameter of the cable, which is supposed to lie
always one coil thick upon it. The force of a man, thus applied, has
been commonly estimated as equal to the traction of 27 pounds hanging
over a pulley.
Friction being so variable a quantity in capstans, renders the exact
calculation of its mechanical effect somewhat uncertain.
A stout man, stationed near the bottom of the axle, holds fast the loose
part of the cable, which has already made two or three turns; and, being
aided by its friction upon the wood, he both prevents it from slipping
backwards, and uncoils each turn as it is progressively made.
Mr. Hindmarsh, master mariner of Newcastle, obtained a patent, in
February, 1827, for a contrivance to enable a capstan or windlass to be
occasionally worked with increased mechanical advantage. With this view,
he placed toothed wheel-work, partly in the drum-head of the capstan,
and partly in the upper part of the barrel, upon which the cable is
coiled and uncoiled in successive portions.
The drum-head, and also the barrel, turn loosely upon a central spindle,
independent of each other, and are connected together either by the
toothed geer, or by bolts. On raising or withdrawing the connecting
pinion from the toothed wheels, and then locking the drum-head and
barrel together, the capstan works with a power equal only to that
exerted by the men at the capstan-bars, as an ordinary capstan; but on
lowering the pinion into geer with the wheel-work, and withdrawing the
bolts which locked the drum-head to the barrel, the power exerted by the
men becomes increased in proportion to the diameter and numbers of teeth
in the wheels and pinions.
[Illustration: 255 256]
_Fig._ 255. is the external appearance of this capstan. _Fig._ 256. a
horizontal view of the toothed geer at the top of the barrel. The
barrel, with the whelps _a a_, turns loosely upon a verticle spindle
fixed into the deck of the vessel. The drum-head _b_ also turns loosely
upon the same spindle. The circular frame _c c_, in _fig._ 256., in
which the axes of the toothed wheels _d d d_ are mounted, is fixed to
the central spindle. The rim _e e e_, with internal teeth, is made fast
to the top of the barrel; and the pinion _f_, which slides upon the
spindle, is connected to the drum-head.
When it is intended to work the capstan with ordinary power, the pinion
_f_ is raised up into the recess of the drum-head, by means of a screw
_g_, _fig._ 255., which throws it out of geer with the toothed wheels,
and it is then locked up by a pin _z_: the bolts _h h_ are now
introduced, for the purpose of fastening the drum-head and barrel
together, when it becomes an ordinary capstan.
But when it is required that the same number of men shall exert a
greater power, the bolts _h_ are withdrawn, and the pinion _f_ lowered
into geer, with the toothed wheels. The rotation of the drum-head, then
carrying the pinion round, causes it to drive the toothed wheels _d d
d_; and these working into the toothed rim _e e_, attached to the
barrel, cause the barrel to revolve with an increased power.
Thus, under particular circumstances, a smaller number of men at the
capstan or windlass (which is to be constructed upon the same
principle) will be enabled to haul in the cable and anchor, or warp off
the vessel, which is an important object to be effected.
In 1819, Captain Phillips obtained a patent for certain improvements in
capstans, a part of which invention is precisely the same as this in
principle, though slightly varied in its adaptation.
James Brown, ship-rigger, in his capstan, patented in 1833, instead of
applying the moving power by handspikes, having fixed two rims of teeth
round the top of the capstan, acts upon them by a rotatory worm, or
pinions turned by a winch.
[Illustration: 257 258]
_Fig._ 257. is an elevation of this capstan, and _fig._ 258. is a
horizontal top view. a is an upright shaft, fixed firmly to the deck,
serving as an axle round which the body of the capstan revolves. A frame
_c_, fixed to the top of a stationary shaft _a_, above the body of the
capstan, carries the driving apparatus.
The upper part of the body of the capstan has a ring of oblique teeth
_d_ formed round its edge; and above this, on the top of the capstan, is
a ring of bevel teeth _e_. A horizontal shaft _f_, mounted in the top
frame _c_, has a worm or endless screw, which takes into the teeth of
the ring _d_; and a short axle _g_, having its bearings in the central
shaft _a_, and in the frame _c_, carries a bevel pinion, which takes
into the bevel teeth of the ring _c_.
The bearings of the shaft _f_, in the top frame, are in long slots, with
angular returns, something like the fastening of a bayonet, which is for
the purpose of enabling the shaft to be readily lifted in and out of
geer with the teeth of the ring _d_: the outer bearing of the axle _g_
of the bevel pinion is also supported in the frame _c_, in a similar
way, in order to put it in and out of geer with the teeth of the bevel
ring _e_. A mode of shifting these is essential; because the two toothed
rings, and their driving worm and pinion, give different speeds, and, of
course, cannot be both in operation at the same time.
The worm of the shaft _f_, being placed in geer with the teeth of the
ring _d_, on applying rotatory power thereto, by means of winches
attached to the ends of the shaft, the barrel or body of the capstan
will be made to revolve with a slow motion, but with great power; and
thus two men at the winches will do the same work as many men with
capstan bars in the ordinary way.
If a quicker movement than that of the endless screw is desired, then
the driving power may be applied by a winch to the axle _g_ of the bevel
pinion, that pinion being put into geer with the bevel ring _e_, and the
endless screw withdrawn. It should, however, be here remarked, that the
patentee proposes to employ two short axles _g_, placed opposite to each
other, with bevel pinions acting in the bevel-toothed ring, though only
one is shown in the figure to avoid confusion. He also contemplates a
modification of the same contrivance, in which four short axles _g_,
placed at right angles, with pinions taking into a bevel ring, may be
employed, and made effective in giving rotatory motion to the barrel of
a capstan by means of winches applied to the outer ends of the axle, and
turned by the labour of four men.
CARAT or CARACT is a weight used by goldsmiths and jewellers. See ASSAY
and DIAMOND.
CARBON, (_Carbone_, Fr.; _Kohlenstoff_, Germ.) in a perfectly pure
state, constitutes diamond. Carbonaceous substances are usually more or
less compound, containing hydrogen, or sometimes oxygen, and azote,
along with earthy and metallic matters. Carbon, tolerably pure, abounds
in the mineral kingdom; and, in a combined state, it forms a main
constituent of vegetable and animal bodies. Anthracite is a mineral
charcoal, differing from common pit-coal in containing no bitumen, and,
therefore, burning without flame or smoke. _Coke_ is the carbonaceous
mass which remains after pit-coal has been exposed to ignition for some
time out of contact of air; its volatile parts having been dissipated by
the heat. It is a spongy substance, of an iron-black colour, a somewhat
metallic lustre, and does not easily burn unless several pieces are
kindled together. With a good draught, however, it produces a most
intense heat. _Wood charcoal_ is obtained by the calcination of wood in
close vessels, as described under the article ACETIC ACID, or in piles
of various shapes, covered with loam, to screen it from the free action
of the atmosphere, which would otherwise consume it entirely. See
CHARCOAL. Such carbon is a solid, without smell or taste, and bears the
strongest heats of our furnaces without suffering any change, provided
air be excluded: it is a bad conductor of heat, but conducts electricity
very well. When burned, it unites with oxygen, and forms carbonic acid,
the fixed air of Dr. Black, the choke-damp of the miner. When this
carbonic acid is made to traverse red hot charcoal it dissolves a
portion of it, and becomes carbonic oxide, which contains only one half
of its volume of oxygen; whereas carbonic acid consists of one volume of
oxygen combined with one volume of the vapour of carbon, the two being
condensed into one volume. If the specific gravity of oxygen, = 1·1025,
be deducted from that of carbonic acid, = 1·5245, the difference, =
0·422, will be the specific gravity of the vapour of carbon; as well as
the proportion present in that weight of the acid.
[Illustration: 259 260 261 262]
Charcoal obtained by the action of a rapid fire in close vessels is not
so solid and so good a fuel as that which is made in the ancient way by
the slow calcination of pyramidal piles covered with earth. One of the
most economical ovens for making wood charcoal is that invented by M.
Foucauld, which he calls a _shroud_, or _abri_. To construct one of
these, 30 feet in diameter at the base, 10 feet at its summit, and from
8 to 9 feet high, he forms, with wood 2 inches square, a frame 12 feet
long, 3 feet broad at one end, and one foot at the other. The figure
will explain the construction. The uprights, A B and C D, of this frame
are furnished with three wooden handles _a a a_, and _a´ a´ a´_, by
means of which they can be joined together, by passing through two
contiguous handles a wooden fork, the frame being previously provided
with props, as shewn in _fig._ 259, and covered with loam mixed with
grass. A flat cover of 10 feet diameter, made of planks well joined, and
secured by four cross bars, is mounted with two trap doors, M N, _fig._
261., for giving egress to the smoke at the commencement of the
operation; a triangular hole P, cut out in the cover, receives the end
of a conduit Q R S, (_figs._ 262. and 261.) of wood formed of three
deals, destined to convey the gases and condensed liquids into the casks
F G H. Lastly, a door T, which may be opened and shut at pleasure,
permits the operator to inspect the state of the fire. The charcoal
calcined by this _abri_, has been found to be of superior quality.
When it is wished to change the place where the _abri_ is erected, and
to transport it to a store of new-felled timber, the frame is taken
down, after beating off the clay which covers it, the joints are then
cut by a saw, as well as the ends of the forks which fixed the frames to
one another. This process is economical in use, simple and cheap in
construction; since all the pieces of the apparatus are easily moved
about, and may be readily mounted in the forests. For obtaining a
compact charcoal, for the use of artisans, this mixed process of
Foucauld is said to be preferable to either the close iron cylinder or
the pile.
For making gunpowder-charcoal the lighter woods, such as the willow,
dogwood, and alder answer best; and in their carbonization care should
be taken to let the vapours freely escape, especially towards the end of
the operation, for when they are re-absorbed, they greatly impair the
combustibility of the charcoal.
By the common process of the forests, about 18 per cent. of the weight
of the wood is obtained; by the process of Foucauld about 24 per cent.
are obtained, with 20 of crude pyrolignous acid of 10 degrees Baumé. By
the process described under ACETIC ACID, 27 of charcoal, and 18 of acid
at 6 degrees, are procured from 100 parts of wood, besides the tar.
These quantities were the results of careful experimenting, and are
greater than can be reckoned upon in ordinary hands.
Charcoal for chemical purposes may be extemporaneously prepared by
calcining pieces of wood covered with sand in a crucible, till no more
volatile matter exhales.
The charcoal of some woods contains silica, and is therefore useful for
polishing metals. Being a bad conductor of heat, charcoal is employed
sometimes in powder to encase small furnaces and steam-pipes. It is not
affected by water; and hence, the extremities of stakes driven into
moist ground are not liable to decomposition. In like manner casks when
charred inside preserve water much better than common casks, because
they furnish no soluble matter for fermentation or for food to
animalcules.
Lowitz discovered that wood charcoal removes offensive smells from
animal and vegetable substances, and counteracts their putrefaction. He
found the odour of succinic and benzoic acids, of bugs, of empyreumatic
oils, of infusions of valerian, essence of wormwood, spirits distilled
from bad grain, and sulphureous substances were all absorbable by
freshly calcined charcoal properly applied. A very ingenious filter has
been constructed for purifying water, by passing it through strata of
charcoal of different fineness.
When charcoal is burned, one third of the heat is discharged by
radiation, and two thirds by conduction.
The following table of the quantity of charcoal yielded by different
woods was published by Mr. Mushet, as the result of experiments
carefully made upon the small scale. He says, the woods before being
charred were thoroughly dried, and pieces of each kind were selected as
nearly alike in every respect as possible. One hundred parts of each
sort were taken, and they produced as under:--
Lignum Vitæ afforded 26·0 of charcoal of a greyish colour, resembling
coke.
Mahogany 25·4 tinged with brown, spongy and porous.
Laburnam 24·5 velvet black, compact, very hard.
Chesnut 23·2 glossy black, compact, firm.
Oak 22·6 black, close, very firm.
Walnut 20·6 dull black, close, firm.
Holly 19·9 dull black, loose and bulky.
Beech 19·9 dull black, spongy, firm.
Sycamore 19·7 fine black, bulky, moderately firm.
Elm 19·5 fine black, moderately firm.
Norway Pine 19·2 shining black, bulky, very soft.
Sallow 18·4 velvet black, bulky, loose and soft.
Ash 17·9 shining black, spongy, firm.
Birch 17·4 velvet black, bulky, firm.
Scottish Pine 16·4 tinged with brown, moderately firm.
Messrs. Allen and Pepys, from 100 parts of the following woods, obtained
the quantities of charcoal as under:--
Beech 15·00
Mahogany 15·75
Lignum Vitæ 17·25
Oak 17·40
Fir 18·17
Box 20·25
It is observable that the quantities obtained by Messrs. Allen and Pepys
are in general less than those given by Mr. Mushet, which may be owing
to Mr. Mushet not having applied sufficient heat, or operated long
enough, to dissipate the aqueous matter of the gaseous products.
To those persons who buy charcoal by weight, it is important to purchase
it as soon after it is made as possible, as it quickly absorbs a
considerable portion of water from the atmosphere. Different woods,
however, differ in this respect. Messrs. Allen and Pepys found that by a
week’s exposure to the air, the charcoal of
Lignum Vitæ gained 9·6 per cent.
Fir 13·0 ditto.
Box 14·0 ditto.
Beech 16·3 ditto.
Oak 16·5 ditto.
Mahogany 18·0 ditto.
The following is a tabular view of the volumes of the different gases
which were absorbed in the course of 24 hours, by one volume of
charcoal, in the experiments of M. Theodore de Saussure, which were
conducted in a way likely to produce correct results. Each portion of
charcoal was heated afresh to a red heat, and allowed to cool under
mercury. When taken from the mercury, it was instantly plunged into the
vessel of gas.
Ammoniacal gas 90
Muriatic acid gas 85
Sulphurous acid 65
Sulphuretted hydrogen 55
Nitrous oxide 40
Carbonic acid gas 35
Bicarburetted hydrogen 35·00
Carbonic oxide 9·42
Oxygen gas 9·25
Nitrogen 7·50
Carburetted hydrogen 5·00
Hydrogen gas 1·75
Neumann, who made many experiments on charcoal, informs us that for the
reduction of the metallic oxides, the charcoal of the heavier woods, as
that of the oak and the beech, is preferable, and that, for common fuel,
such charcoal gives the greatest heat, and requires the most plentiful
supply of air to keep it burning; while those of the lighter woods
preserve a glowing heat with a much less draught of air; and that for
purposes where it is desirable to have a steady and a still fire,
charcoal should be employed which has been made from wood previously
divested of its bark, since it is the cortical part which crackles and
flies off in sparks during combustion, while the coal of the wood itself
seldom does.
For making crayons of charcoal, the willow is the best wood that can be
employed, as the softness is uniform in all its parts. Its durability
may be seen in several of our old churchyards, where the letters made
with lamp-black are still perfect, though the white lead with which the
body of the stones was painted is entirely destroyed.
This property of carbon is shewn, however, in a more striking manner by
the writings that were found in the ruins of Herculaneum, which have
retained their original blackness for two thousand years. The ancients
wrote with ink made from ground charcoal.
If it be required to purify any carbonaceous matter, to render it fitter
for delicate pigments, this may be done by first calcining it in a close
vessel, and then lixiviating it in water slightly acidulated by nitric
acid.
The incorruptibility of charcoal was well known to the ancients, and
they availed themselves of this property upon all important occasions.
About sixty years ago a quantity of oak stakes were found in the bed of
the Thames, in the very spot where Tacitus says that the Britons fixed a
vast number of such stakes, to prevent the passage of Julius Cæsar and
his army. These stakes were charred to a considerable depth, had
retained their form completely, and were firm at the heart.
Most of the houses in Venice stand upon piles of wood, which have all
been previously charred for their preservation. In this country, estates
were formerly marked out by charred stakes driven to a considerable
depth into the ground. See BONE-BLACK, CHARCOAL, and GRAPHITE.
CARBONATED WATER, is water either pure, or holding various saline
matters in solution, impregnated with carbonic acid gas. For general
sale in this country, the water usually contains a little soda, which
being charged with the gas, is called _Soda water_; see this article for
a description of an excellent machine for the manufacture of this
fashionable beverage.
CARBONATES. Saline compounds in definite proportions, of carbonic acid,
with alkalis, earths, and the ordinary metallic oxides.
The carbonates principally used in the arts and manufactures are those
of _ammonia_, _copper_, _iron_, _lead_, _lime_, _magnesia_, _potash_,
_soda_. Native carbonate of copper is the beautiful green mineral called
Malachite.
Carbonates are easily analyzed by estimating either by weight or measure
the quantity of carbonic acid which they evolve under the decomposing
action of somewhat dilute sulphuric, nitric, or muriatic acid; for as
they are all compounds of acid, and base in equivalent proportions, the
quantity of acid will indicate the quantity of base. Thus, as pure
limestone consists of 56 of lime and 44 of acid, in 100 parts, if upon
examining a sample of limestone we find it to give out only 22 per cent.
of carbonic acid gas, during its slow solution in muriatic acid, we are
sure that there are only 28 parts of lime present. I have described, in
the Annals of Philosophy, for October, 1817, a simple form of apparatus
for analyzing the carbonates with equal readiness and precision. The
simple rule by _measure_ to which I was led, may be thus stated: _From
the bulk of evolved gas, expressed in cubic inches and tenths, deduct
1/20, the remainder will express the proportion of real limestone
present in the grains employed._ Pure magnesian limestone yields very
nearly a cubic inch of the gas for every grain in weight.
CARBONATE OF AMMONIA. A salt called in modern chemistry
_sesquicarbonate_, to denote its being composed of one and a half
equivalent primes of carbonic acid, and one of ammonia. It consists by
my analysis of 55·89 carbonic acid, 28·86 ammonia, and 15·25 water, in
100 parts. It is generally prepared by mixing from 1-1/4 to 1-1/2 parts
of well-washed dry chalk, with 1 of sal-ammoniac, introducing the
mixture into an earthen or cast-iron retort, or subliming pot, and
exposing it to a heat gradually raised to redness. By double
decomposition, the ammonia is volatilized in combination with the
carbonic acid of the chalk, and the vapours are received in a condensing
receiver made either of glass, stone ware, or lead. The chlorine of the
sal-ammoniac remains in the retort, associated with the basis of the
chalk in the state of chloride of calcium. Some ammonia gas escapes
during the process.
The saline mass thus sublimed is purified by a second sublimation in
glass, or salt-glazed earthen vessels. The salt may be obtained, by the
above method carefully conducted, in rhomboidal octahedrons, but it is
generally made for the market in a compact semi-crystalline white cake.
It has a pungent ammoniacal smell, a hot, pungent, alkaline taste, a
strong alkaline reaction, and dissolves in two parts of cold water. It
must be kept in well-closed vessels, as by exposure to the air a portion
of its ammonia exhales, and it passes into the state of the scentless
bi-carbonate. It is employed much in medicine, chemical analysis, and by
the pastry-cooks to give sponginess to their cakes in consequence of its
volatilization from their dough in the oven. See SAL-AMMONIAC.
For the other carbonates used in the arts, see their respective bases;
copper, lead, lime, &c.
CARBONIC ACID (_Acide carbonique_, Fr.; _Kohlensäure_, Germ.), consists
of 1 prime equivalent of carbon = 6·125 + 2 of oxygen = 16·026, whose
joint sum = 22·151, represents the atomic weight or combining ratio of
this acid, in the neutral or protocarbonate salts. Its composition by
volume is stated under CARBON. Its natural form is a gas, whose specific
gravity is 1·5245, compared to atmospheric air 1·000; and being so
dense, it may be poured out of one vessel into another. Hence it was
called at first _aërial acid_. From its existing copiously, in a solid
state, in limestones and the mild alkalies, it was styled _fixed air_ by
its proper discoverer, Dr. Black. About one volume of it exists in 1000
volumes of common atmospheric air, which may be made manifest by the
crust of carbonate it occasions upon the surface of lime water. Carbonic
acid gas is found accumulated in many caverns of volcanic districts, and
particularly in the _grotto dei cani_ at Pausilippo, near Puzzuoli;
being disengaged in such circumstances by the action of subterranean
fire, and, possibly, of certain acids, upon the limestone strata. It
often issues from fountains in copious currents, as at Franzensbrunn,
near Eger, in Polterbrunnen; near Trier; and Byrreshorn. This acid gas
occurs also frequently in mines and wells, being called _choke damp_,
from its suffocating quality. Its presence may, at all times, be
detected, by letting down a lighted candle, suspended from a string,
into the places suspected of containing this mephitic air. It exists, in
considerable quantities, in the water of every pump well, and gives it a
fresh and pleasant taste. Water, exposed some time to the air, loses
these aerial particles, and becomes vapid. Many springs are highly
impregnated with carbonic acid gas, and form a sparkling beverage; such
as the _Selterswasser_, from Selters upon the Lahn, in the grand duchy
of Nassau; of which no less than two millions and a half of bottles are
sold every year. A prodigious quantity of a similar water is also
artificially prepared in Great Britain, and many other countries, under
the name of aërated or soda water.
Carbonic acid occurs in nature, combined with many salifiable bases; as
in the carbonates of soda, baryta, strontia, magnesia; the oxides of
iron, manganese, zinc, copper, lead, &c. From these substances it may be
separated, generally speaking, by strong ignition, or, more readily, by
the superior affinity of muriatic, sulphuric, or nitric acid, for the
earth or metallic oxide. It is formed whenever vegetable or animal
substances are burned with free access of air, from the union of their
carbonaceous principle with atmospheric oxygen. It is also formed in all
cases of the spontaneous decomposition of organic substances,
particularly in the process of fermentation; and constitutes the
pungent, noxious, heavy gas thrown off, in vast volumes, from beer vats.
See DISTILLATION and FERMENTATION. Carbonic acid is also generated in
the breathing of animals; from 4 to 5 per cent., in volume, of the
inhaled oxygen being converted, at each expiration, into this gas, which
contaminates the air of crowded apartments, and renders ventilation
essential to health, and even to life: witness the horrible catastrophe
of the Black-hole at Calcutta.
Carbonic acid gas is destitute of colour, has a sourish, suffocating
smell, an acidulous pungent taste, imparts to moist, but not dry, litmus
paper, a transient reddish tint, and weighs per 100 cubic inches, 46-1/2
grains; and per cubic foot, 803-1/2 grains; a little more than 3-3/4 oz.
avoirdupoid. A cubic foot of air weighs about two thirds of that
quantity, or 527 grains. It may be condensed into the liquid state by a
pressure of 40 atmospheres, and this liquid may be then solidified by
its own sudden spontaneous evaporation. If air contain more than 15 per
cent. in bulk of this gas, it becomes unfit for respiration and
combustion, animal life and candles being speedily extinguished by it.
Before a person ventures into a deep well, or vault containing
fermenting materials, he should introduce a lighted candle into the
space, and observe how it burns. Carbonic acid, being so much denser
than common air, may be drawn out of cellars or fermenting tubs, by a
pump furnished with a leather hose, which reaches to the bottom.
Quicklime, mixed with water, may be used also to purify the air of a
sunk apartment by its affinity for, or power of, absorbing this aërial
acid. See MINERAL WATERS and SODA WATER.
CARBONIC OXIDE. See the article CARBON.
CARBUNCLE. A gem highly prized by the ancients; most probably a variety
of the noble garnet of modern mineralogists.
CARBURET OF SULPHUR, called also sulphuret of carbon, and alcohol of
sulphur, is a limpid volatile liquid, possessing a penetrating fetid
smell, and an acrid burning taste. Its specific gravity is 1·265; and
its boiling point is about 112° Fahr. It evaporates so readily, and
absorbs so much heat in the vaporous state, that if a tube containing
quicksilver, surrounded with lint dipped in this liquid, be suspended in
the receiver of an air-pump, on making the vacuum, the quicksilver will
be congealed. It consists of 15·8 carbon and 84·2 sulphur, in 100 parts;
being two equivalent primes of the latter to one of the former.
CARBURETTED HYDROGEN. A compound of carbon and hydrogen, of which there
are several species--such as oil-gas, coal-gas, olefiant gas, oil of
lemons, otto of roses, oil of turpentine, petroleum, naphta,
naphthaline, oil of wine, caoutchoucine and caoutchouc.
CARDS, PLAYING. (_Cartes à jouer_, Fr.; _Karten_, Germ.) Mr. de la Rue
obtained, in February, 1832, a patent for certain improvements in the
manufacture of playing cards, which he distributed under three heads:
first, printing the pips, and also the picture or court-cards, in oil
colours by means of types or blocks; secondly, effecting the same in oil
colours by means of lithography; and thirdly, gilding or silvering
borders, and other parts of the characters, by the printing process,
either by types, blocks, or lithography.
In the ordinary mode of manufacturing playing cards, their devices are
partly produced by copperplate printing, and they are filled up with
water colours by the means called stencilling.
The patentee does not propose any material alteration in the devices or
forms upon the cards, but only to produce them with oil colours; and, to
effect this, he follows precisely the same mode as that practised by
calico printers.
A set of blocks or types properly devised, are produced for printing the
different pips of hearts, diamonds, spades, and clubs, or they are
drawn, as other subjects, in the usual way upon stone. The ink or
colour, whether black or red, is to be prepared from the best French
lamp-black, or the best Chinese vermillion ground in oil, and laid on
the types and blocks, or on the stone, in the same way as printers’ ink,
and the impressions taken-on to thick drawing paper by means of a
suitable press in the ordinary manner of printing.
The picture or court-cards are to be produced by a series of impressions
in different colours, fitting into each other exactly in the same way as
in printing paper hangings, or silks and calicoes, observing that all
the colours are to be prepared with oil.
For this purpose a series of blocks or types are to be provided for each
subject, and which, when put together, will form the whole device. These
blocks are to be used separately, that is, all the yellow parts of the
picture, for instance, are to be printed at one impression, then all the
red parts, next all the flesh colour, then the blue portions, and so on,
finishing with the black outlines, which complete the picture.
If the same is to be done by lithography, there must be as many stones
as there are to be colours, each to print its portion only; and the
impression, or part of the picture given by one stone, must be exactly
fitted into by the impression given from the next stone, and so on until
the whole subject is complete.
A superior kind of card is proposed to be made, with gold or silver
devices in parts of the pictures, or gold or silver borders round the
pips. This is to be effected by printing the lines which are to appear
as gold or silver, with gilders’ size, in place of ink or colour; and
immediately after the impression has been given, the face of the card is
to be powdered over with gold dust, silver, or bronze, by means of a
soft cotton or wool dabber, by which the gold, silver, or bronze will be
made to adhere to the picture, and the superfluous portions of the metal
will wipe off by a very slight rubbing. When the prints are perfectly
dry, the face of the card may be polished by means of a soft brush.
If it should be desirable to make these improved cards to resemble
ivory, that may be done by preparing the face of the paper in the first
instance with a composition of size and fine French white, and a drying
oil, mixed together to about the consistence of cream; this is to be
washed over the paper, and dried before printing, and when the cards are
finished, they will exactly resemble ivory.
The only thing remaining to be described, is the means by which the
successive impressions of the types, blocks, or stones forming the parts
of the pictures, are to be brought exactly to join each other, so as to
form a perfect whole design when complete; this is by printers called
registering, and is to be effected much in the usual way, by points in
the tympan of the press, or by marks upon the stones.
The parts of the subject having been all accurately cut or drawn to fit,
small holes are to be made with a fine awl through a quire or more of
the paper at once, by placing upon the paper a gauge-plate, having marks
or guide-holes, and by observing these, the same sheet laid on several
times, and always made to correspond with the points or marks, the
several parts of the picture must inevitably register, and produce a
perfect subject.
CARD CUTTING. Mr. Dickinson’s patent machine for cutting cards, consists
of a pair of rollers with circular revolving cutters, the edges of which
are intended to act against each other as circular shears, and the
pasteboards in passing between these rollers are cut by the circular
shears into cards of the desired dimensions. These rollers are mounted
in suitable standards, with proper adjustments, and are made to revolve
by a band and pulley connected to the axle of a crank, or by any other
convenient means.
[Illustration: 263 264 265 266]
_Fig._ 263. is a front view of this machine; _a a_ and _b b_ are the two
rollers, the upper one turning upon an extended axle, bearing in the
standards, the lower one upon pivots. These rollers are formed by a
series of circular blocks, between a series of circular steel cutters,
which are slidden on to iron shafts, and held together upon their axle
by nuts screwed up at their ends. The accurate adjustment of the cutters
is of the first importance to their correct performance; it is therefore
found necessary to introduce spiral springs within the blocks, in order
to press the cutters up to their proper bearings. A section of one of
the blocks is shewn at _fig._ 265, and an end view of the same at _fig._
266, with the spiral springs inserted.
At the outer extremity of the axle of the roller _a_, a rigger _c_, is
attached, whence a band passes to a pulley _d_, on the crank shaft _e_,
to which a flywheel _f_, is affixed, for the purpose of rendering the
action uniform. Rotatory motion being given to the crank shaft, the
upper roller is turned, the lower roller moving at the same time by the
friction against the edges of the cutters.
_Fig._ 264 is an end view of the rollers, showing the manner in which
the pasteboards are guided and conducted between the cutters. In the
front of the machine a movable frame _g_, is to be placed, for the
purpose of receiving the pasteboards, preparatory to cutting them into
cards, and a stop is screwed to this frame for the edge of the
pasteboard to bear against, which stop is adjustable to suit different
sizes. From the back part of this frame an arm _h_, extends, the
extremity of which acts against the periphery of a ratchet wheel _i_,
fixed at the end of the roller _b_, and hence, as the roller goes round,
the frame is made to rise and fall upon its pivots, for the purpose of
guiding the pasteboard up to the cutters; at the same time a rod _k_,
hanging in arms from the sides of the standards (shewn by dots in _fig._
263), falling upon the pasteboard, confines it, while the cutters take
hold, and racks, corresponding with the indentations of the rollers, are
placed as at _l l_, by means of which the cards, when cut, are pushed
out of the grooves.
As various widths of cards will require to be cut by this machine, the
patentee proposes to have several pairs of rollers ready adjusted to act
together, when mounted in the standards, in preference to shifting the
circular cutters, and introducing blocks of greater or less width.
The second part of the invention is a machine for pasting the papers,
and pressing the sheets together to make pasteboard. This machine
consists of several reels (we suppose rollers are intended) on which the
paper is to be wound, along with a paste trough, and rotatory brushes.
The several parts of this machine, and their operations in making
pasteboard, are described in the specification, but the patentee having
omitted the letters of reference in the drawing which he has enrolled,
it becomes difficult to explain it.
As far as we are enabled to understand the machine, it appears, that
damped paper is to be wound upon two rollers, and conducted from thence
over two other rollers; that two fluted rollers revolving in the paste
trough are to supply paste to two circular brushes, and that by those
brushes the papers are to be pasted upon one side, and then pressed
together, to make the pasteboard; after this, the pasteboard is to be
drawn on to a table, and to remain there until sufficiently dry to be
wound upon other rollers. By comparing this description with the figure,
perhaps the intended operations of the machine may be discovered, it is
the best explanation we are enabled to give.
CARDS, (_Cardes_, Fr.; _Karden_, Ger.) are instruments which serve to
disentangle the fibres of wool, cotton, or other analogous bodies, to
arrange them in an orderly lap or fleece, and thereby prepare them for
being spun into uniform threads. The fineness and the levelness of the
yarn, as well as the beauty of the cloth into which it enters, depend
as much upon the regularity and perfection of the carding, as upon any
subsequent operations of the factory. The quality of the carding depends
more upon that of the cards than upon any attention or skill in the
operative; since it is now nearly an automatic process, conducted by
young women called card-tenters.
Cards are formed of a sheet or fillet of leather pierced with a
multitude of small holes, in which are implanted small staples of wire
with bent projecting ends called _teeth_. Thus every piece of wire is
double toothed. The leather is afterwards applied to a flat or
cylindrical surface of wood or metal, and the co-operation of two or
more such surfaces constitutes a card. The teeth of cards are made
thicker or slenderer, according as the filaments to be carded are
coarser or finer, stiffer or more pliant, more valuable or cheaper. It
is obviously of great importance that the teeth should be all alike,
equably distributed, and equally inclined over the surface of the
leather, a degree of precision which is scarcely possible with handwork.
To judge of the difficulty of this manipulation we need only inspect the
annexed figures. The wire must first be bent at right angles in _c_ and
_d_, _fig._ 268, then each branch must receive a second bend in _a_ and
_b_ at a determinate obtuse angle, invariable for each system of cards.
It is indispensable that the two angles _c a e_ and _d b f_ be
mathematically equal, not only as to the twin teeth of one staple, but
through the whole series; for it is easy to see that if one of the teeth
be more or less sloped than its fellow, it will lay hold of more or less
wool than it, and render the carding irregular. But though the perfect
regularity of the teeth be important, it is not the sole condition
towards making a good card. It must be always kept in view that these
teeth are to be implanted by pairs in a piece of leather, and kept in it
by the cross part _c d_. The leather must therefore be pierced with twin
holes at the distance _c d_; and pierced in such a manner, that the
slope of the holes, in reference to the plane of the leather, be
invariably the same; for otherwise the length of the teeth would vary
with this angle of inclination, and the card would be irregular.
[Illustration: 267 268 269]
A third condition essential towards producing perfect regularity, is
that the leather ought to be of the same thickness throughout its whole
surface, otherwise the teeth, though of the same length and fixed at the
same angle, would be rendered unequal by the different thicknesses of
the leather, and the operation of carding would be in consequence
extremely defective. _Fig._ 267. shows the card-teeth acting against
each other, as indicated by the arrows in two opposite directions; in
_fig._ 269. they work one way.
Of late years very complex but complete and well-acting machines have
been constructed for splitting the leather or equalizing it by shaving,
for bending and cutting the wires, and implanting them in the leather,
into holes pierced with perfect regularity. Card machines which fashion
the teeth with great precision and rapidity, and pierce the leather,
have been for a considerable time in use at Halifax, in Yorkshire, a
town famous for the excellence of its card-cloth, as also at Leeds,
Glasgow, and several other places. The wires and the leather thus
prepared are given out by the manufacturer to women and children, who
put them together.
1. The simplest machine for equalizing the leather which can be
employed, is that which I saw operating in MM. Scrive’s automatic card
factory at Lille, the most magnificent I believe in the world, where the
leather was drawn forwards by a roller over a solid horizontal table, or
bed, and passed under a nicely adjusted vertical blade, which shaved it
by a scraping motion to a perfectly uniform thickness. About one half
the weight of the leather is lost in this process, and in the subsequent
squaring and trimming.
The machine for making cards, invented I believe by a Mr. Ellis of the
United States, for which a first patent was obtained in this country by
Joseph Cheeseborough Dyer, Esq. of Manchester, in 1811, and a second and
third with further improvements in 1814, and 1824, is one of the most
elegant automatons ever applied to productive industry. It is however
necessarily so complicated with different mechanisms as to render its
representation impracticable in such engravings as are compatible with
the scope of this dictionary. I must therefore content myself with the
following general description of its constituent parts.
The first thing to be done after having, as above, prepared the long
sheets or fillets of leather, of suitable length, breadth, and
thickness, for making the cards, is to stretch the leather, and hold it
firmly; which is accomplished by winding the fillet of leather upon the
roller or drum, like the warp roller of a loom, and then conducting it
upwards between guide rollers, to a receiving or work roller at top of
the machine, where the fillet is held fast by a cramp, by which means
the leather is kept stretched.
Secondly, the holes are pierced in the leather to receive the wire
staples or teeth of the card, by means of a sliding fork, the points of
which are presented to the face of the leather; while the fork is made
to advance and recede continually, by the agency of levers worked by
rotatory cams upon a revolving main shaft.
The points of the fork being thus made to penetrate into the leather,
the holes for receiving the staples are pierced, at regular distances,
and in correct order, by shifting the leather fillet so as to bring
different parts of its surface opposite to the points of the sliding
fork. This is done by cams, or indented wheels and gear, which shift the
guide rollers and confining drums laterally, as they revolve, and
consequently move the fillet of leather at intervals a short distance,
so as to present to the points of the fork or piercer at every movement,
a different part of the surface of the leather.
Thirdly, the wire of which the teeth or points of the card are to be
made, is supplied from a coil on the side of the machine, and is brought
forward at intervals, by a pair of sliding pincers, which are slidden to
and fro through the agency of levers actuated by rotatory cams upon the
main shaft. The pincers having advanced a distance equal to the length
of wire intended to form one staple, or two points, this length of wire
is pressed upon exactly in the middle by a square piece of steel, and
being there confined, a cutter is brought forward, which cuts it off
from that part of the wire held in the pincers.
The length of wire thus separated and confined, is now, by a movement of
the machine, bent up along the sides of the square steel holder, and
shaped to three edges of the square, that is, formed as a staple; and in
the same way, by the continued movements of the machine, a succession of
pieces of wire are cut off, and bent into staples for making the teeth
of the card as long as the mechanism is kept in action.
Fourthly, the wire staple thus formed is held with its points or ends
outwards, closely contiguous to the forked piercer described above, and
by another movement of the mechanism, the staple is protruded forward,
its end entering into the two holes made previously in the leather by
the sliding of the fork.
While the wire staple is being thus introduced into the leather, its
legs or points are to be bent, that is, formed with a knee or angle,
which is the fifth object to be effected. This is done by means of a
small apparatus consisting of a bar or bed, which bears up against the
under side of the wire staple when it has been passed half-way into the
holes in the leather, and another bar above it, which being brought down
behind the staple, bends it over the resisting bar to the angle
required; that is, forms the knee in each leg. A pusher now acts behind
the staple, and drives it home into the leather, which completes the
operation.
The leather being thus conducted, and its position shifted before the
piercer progressively, a succession of the above described operations of
cutting the wire, forming the staple, passing it into the leather, and
bending its legs to the angular form, produces a sheet of card of the
kind usually employed for carding or combing wool, cotton, and other
fibrous materials. It may be necessary to add, that as these wire
staples are required to be set in the leathers sometimes in lines
crossing the sheet, which is called ribbed, and at other times in
oblique lines, called twilled, these variations are produced by the
positions of the notches or steps upon the edge or periphery of the cam
or indented wheel, which shifts the guide rollers that hold the fillet
or sheet of leather as already described.
CARMINE, (Eng. and Fr.; _Karminstoff_, Ger.), is, according to Pelletier
and Caventou, a triple compound of the colouring substance, and an
animal matter contained in cochineal, combined with an acid added to
effect the precipitation. The preparation of this article is still a
mystery, because upon the one hand, its consumption being very limited,
few persons are engaged in its manufacture, and upon the other, the raw
material being costly, extensive experiments on it cannot be
conveniently made. Success in this business is said to depend not a
little upon dexterity of manipulation, and upon knowing the instant for
arresting the further action of heat upon the materials.
There is sold at the shops different kinds of carmine, distinguished by
numbers, and possessed of a corresponding value. This difference depends
upon two causes, either upon the proportion of alumina added in the
precipitation, or of a certain quantity of vermillion put in to dilute
the colour. In the first case the shade is paler, in the second, it has
not the same lustre. It is always easy to discover the proportion of the
adulteration. By availing ourselves of the property of pure carmine to
dissolve in water of ammonia, the whole foreign matter remains
untouched, and we may estimate its amount by drying the residuum.
_To make Ordinary Carmine._
Take 1 pound of cochineal in powder;
3 drachms and a half of carbonate of potash;
8 drachms of alum in powder;
3 drachms and a half of fish-glue.
The cochineal must be boiled along with the potash in a copper
containing five pailfuls of water (60 pints); the ebullition being
allayed with cold water. After boiling a few minutes the copper must be
taken from the fire, and placed on a table at such an angle as that the
liquor may be conveniently transvased. The pounded alum is then thrown
in, and the decoction is stirred; it changes colour immediately, and
inclines to a more brilliant tint. At the end of fifteen minutes the
cochineal is deposited at the bottom, and the bath becomes as clear as
if it had been filtered. It contains the colouring matter, and probably
a little alum in suspension. We decant it then into a copper of equal
capacity, and place it over the fire, adding the fish-glue dissolved in
a great deal of water, and passed through a searce. At the moment of
ebullition, the carmine is perceived to rise up to the surface of the
bath, and a coagulum is formed, like what takes place in clarifications
with white of egg. The copper must be immediately taken from the fire,
and its contents be stirred with a spatula. In the course of fifteen or
twenty minutes the carmine is deposited. The supernatant liquor is
decanted, and the deposit must be drained upon a filter of fine canvas
or linen. If the operation has been well conducted, the carmine when dry
crushes readily under the fingers. What remains after the precipitation
of the carmine is still much loaded with colour, and may be employed
very advantageously for carminated lakes. See LAKE.
By the _old German process_ carmine is prepared by means of alum without
any other addition. As soon as the water boils the powdered cochineal is
thrown into it, stirred well, and then boiled for six minutes; a little
ground alum is added, and the boiling is continued for three minutes
more; the vessel is removed from the fire, the liquor is filtered and
left for three days in porcelain vessels, in the course of which time a
red matter falls down, which must be separated and dried in the shade.
This is carmine, which is sometimes previously purified by washing. The
liquor after three days more lets fall an inferior kind of carmine, but
the residuary colouring matter may also be separated by the muriate of
tin.
The proportions for the above process are 580 parts of clear river
water, 16 parts of cochineal, and 1 part of alum; there is obtained from
1-1/2 to 2 parts of carmine.
Another _carmine with tartar_.--To the boiling water the cochineal is
added, and after some time a little cream of tartar; in eight minutes
more we add a little alum, and continue the boiling for a minute or two
longer. Then take it from the fire and pour it into glass or porcelain
vessels, filter and let it repose quietly till the carmine falls down.
We then decant and dry in the shade. The proportions are 8 pounds of
water, 8 oz. of cochineal, 1/2 oz. of cream of tartar, 3/4 oz. of alum,
and the product is an ounce of carmine.
_The process of Alxon or Langlois._--Boil two pails and a half of river
water (30 pints), throw into it, a little afterwards, a pound of
cochineal, add a filtered solution of six drachms of carbonate of soda
and a pound of water, and let the mixture boil for half an hour; remove
the copper from the fire, and let it cool, inclining it to one side. Add
six drachms of pulverized alum, stir with a brush to quicken the
solution of the salt, and let the whole rest 20 minutes. The liquor,
which has a fine scarlet colour, is to be carefully decanted into
another vessel, and there is to be put into it the whites of two eggs
well beat up with half a pound of water. Stir again with a brush. The
copper is replaced on the fire, the alumina becomes concrete, and
carries down the colouring matter with it. The copper is to be taken
from the fire, and left at rest for 25 or 30 minutes to allow the
carmine to fall down. When the supernatant liquor is drawn off, the
deposit is placed upon filter cloth stretched upon a frame to drain.
When the carmine has the consistence of cream cheese, it is taken from
the filter with a silver or ivory knife and set to dry upon plates
covered with paper, to screen it from dust. A pound of cochineal gives
in this way an ounce and a half of carmine.
_Process of Madame Cenette of Amsterdam_, with salt of sorrel.--Into six
pails of river water boiling hot throw two pounds of the finest
cochineal in powder, continue the ebullition for two hours and then add
3 oz. of refined saltpetre, and after a few minutes 4 oz. of salt of
sorrel. In ten minutes more take the copper from the fire and let it
settle for four hours; then draw off the liquor with a syphon into flat
plates and leave it there for three weeks. Afterwards there is formed
upon the surface a pretty thick mouldiness, which is to be removed
dexterously in one pellicle by a slip of whalebone. Should the film tear
and fragments of it fall down, they must be removed with the utmost
care. Decant the supernatant water with a syphon, the end of which may
touch the bottom of the vessel, because the layer of carmine is very
firm. Whatever water remains must be sucked away by a pipette. The
carmine is dried in the shade, and has an extraordinary lustre.
_Carmine by the salt of tin, or the Carmine of China._--Boil the
cochineal in river water, adding some Roman alum, then pass through a
fine cloth to remove the cochineal, and set the liquor aside. It becomes
brighter on keeping. After having heated this liquor, pour into it drop
by drop solution of tin till the carmine be precipitated. The
proportions are one pailful of water, 20 oz. of cochineal and 60 grains
of alum, with a solution of tin containing 4 oz. of the metal.
_To revive or brighten carmine._--We may brighten ordinary carmine, and
obtain a very fine and clear pigment, by dissolving it in water of
ammonia. For this purpose we leave ammonia upon carmine in the heat of
the sun, till all its colour be extracted, and the liquor has got a fine
red tinge. It must be then drawn off and precipitated, by acetic acid
and alcohol, next washed with alcohol, and dried. Carmine dissolved in
ammonia has been long employed by painters, under the name of liquid
carmine.
Carmine is the finest red colour which the painter possesses. It is
principally employed in miniature painting, water colours, and to tint
artificial flowers, because it is more transparent than the other
colours. For _Carminium_, see COCHINEAL.
CARPET. (_Tapis_, Fr.; _Teppich_, Germ.) A thick woollen fabric of
variegated colours, for covering the floors of the better sort of
apartments. This luxurious manufacture took its origin in Persia and
Turkey, whence the most beautiful patterns were wont to come into
Europe; but they have been for some time surpassed by the workmanship of
France, Great Britain, and Belgium. To form a just conception of the
elegant and ingenious processes by which carpets are made, we should
visit the royal establishment of the Gobelins at Paris, where we would
see the celebrated carpet manufactory of the Savonnerie, which has been
transported thither. A detailed set of engravings of this art is given
by Roland de la Platière in the first and second volumes of the
Encyclopédie Méthodique, to which I must refer my readers, as a due
exposition of its machines and operations would far exceed the scope of
the present volume.
The warp, says M. Roland, being the foundation of the fabric, ought to
be of fine wool, equally but firmly spun, and consist of three yarns
twisted into one thread. The yarns that are to form the velvety surface
of the carpet, ought also to be of the best quality, but soft and downy
in their texture, so that the dye may penetrate every filament. Hemp, or
linen yarns, are likewise employed in this manufacture, as a woof, to
bind the warp firmly together after each shoot of the velvety threads.
Thus we see that good carpeting consists essentially of two distinct
webs woven at the same time, and firmly decussated together by the woof
threads. Hence the form of the pattern is the same upon the two sides of
the cloth, only the colours are reversed, so that what was green upon
one side becomes red or black upon the other, and _vice versâ_. The
smaller the figures the more frequent the decussations of the two
planes, and the firmer and more durable the fabric.
The carpet manufacture, as now generally practised, may be distributed
into two systems--that of double fabrics, and that cut in imitation of
velvet. Of late years the Jacquard loom has been much used in weaving
carpets, the nature of which will be found fully explained under that
title.
For the sake of illustration, if we suppose the double carpets to be
composed of only two colours, the principle of weaving will be easily
understood; for it is only necessary to raise the warp of each web
alternately for the passage of the shuttle, the upper web being entirely
above when the under web is being woven, or decussated, and _vice
versâ_. In a Brussels carpet the worsted yarn raised to form the pile,
and make the figure, is not cut; in the Wilton the pile is cut to give
it a velvety aspect and softness. In the imperial Brussels carpet the
figure is raised above the ground, and its pile is cut, but the ground
is uncut; and in the royal Wilton, the pile is both raised higher than
in the common Wilton, and it is cut, whereby it has a rich cushion-like
appearance. The cloth of all these superior carpets consists of woollen
and linen, or hemp; the latter being put upon a beam, and brought, of
course, through heddles and a reed; but as its only purpose is to bind
together the worsted fabric, it should not be visible upon the upper
face of the carpet. The worsted yarn is wound upon small bobbins or
pirns, with a weight affixed to each, for giving proper tension to the
threads. Their number varies, for one web, from 1300 to 1800, according
as the carpet is to be 27 or 36 inches wide; and, they are placed, in
frames, behind the loom, filled with differently coloured yarn, to
correspond with the figure. This worsted warp is then drawn through the
harness, heddles, and reed, to be associated with the linen yarn in the
compound fabric.
In Kidderminster carpeting, both warp and weft appear upon the face of
the cloth, whereas, in the Brussels style, only the warp is seen, its
binding weft being fine hempen or linen threads. The three-ply imperial
carpet, called the Scotch, is coming very much into vogue, and is
reckoned by many to be little inferior in texture, look, and wear to the
Brussels. Kilmarnock has acquired merited distinction by this ingenious
industry. In this fabric, as well as in the two-ply Kidderminster, the
weft predominates, and displays the design; but, in the French carpets,
the worsted warp of the web shows the figure. Plain Venetian carpets, as
used for stairs and passages, are woven in simple looms, provided merely
with the common heddles and reed. The warp should be a substance of
worsted yarn, so heavy as to cover in the weft completely from the view.
Figured Venetian carpets are woven in the two-ply Kidderminster looms,
and are provided with a mechanism to raise the pattern upon the worsted
warp. The weft is an alternate shoot of worsted and linen yarn, and must
be concealed.
[Illustration: 270]
The following figure and description will explain the construction of
the three-ply imperial Scotch and two-ply Kidderminster carpet loom,
which is merely a modification of the Jacquard _métier_. The Brussels
carpet-loom, on the contrary, is a draw-boy loom on the damask plan, and
requires the weaver to have an assistant. _Fig._ 270. A A A, is the
frame of the loom, consisting of four upright posts, with caps and cross
rails to bind them together. The posts are about six feet high. C C, the
cloth-beam, is a wooden cylinder, six inches or thereby in diameter, of
sufficient length to traverse the loom, with iron gudgeons in the two
ends, which work in bushes in the side frame. On one end of this beam is
a ratchet wheel, with a tooth to keep it from turning round backwards by
the tension of the web. D, the lay, with its reed, its under and upper
shell, its two lateral rulers or swords, and rocking-tree above. There
are grooves in the upper and under shell, into which the reed is fitted.
E, the heddles, or harness, with a double neck attached to each of the
tower or card mechanisms F F, of the Jacquard loom. The heddles are
connected and work with the treddles B B, by means of cords, as shown in
the figure. G G are wooden boxes for the cards. H, the yarn, or warp
beam.
[Illustration: 271]
In draw-looms of every kind, there is no sinking of any portion of the
warp, as in plain cloth-weaving; but the plane of the warp is placed
low, and the threads under which the shuttle is to pass are raised,
while all the rest remains stationary. The harness part of this carpet
loom is moved by an assistant boy or girl, who thus allows the weft to
be properly decussated, while the weaver attends to working the front
mounting or heddles. _Fig._ 271., A represents the frame of a carpet
draw-loom; B is a box or frame of pulleys, over which the cords of the
harness pass, and are then made fast to a piece of wood, seen at E,
which the weavers call a table. From the tail of the harness the simples
descend, and to the end of each is attached a small handle G, called a
bob. These handles being disposed in pairs, and their regularity
preserved by means of a perforated board C, it is merely necessary to
pull every handle in succession; the weaver, at the same time, working
his treddles with his feet, as in any other loom. The treddles are four
in number, the fabric being that of plain or alternate cloth, and two
treddles allotted for each web. The harness part of the carpet draw-loom
is furnished with _mails_, or metallic eyes, to save friction; two
threads being drawn through each eye. The design or pattern of a carpet
is drawn upon cross-rule paper, exactly in the same way as every other
kind of fancy-loom work, and is transferred from the paper to the
mounting by the rules for damask weaving. Suppose that a double web is
so mounted that every alternate thread of the one may be raised, so as
to form a sufficient shed-way for the shuttle, without depressing the
other in the least. Then suppose another web placed above the former, at
such a distance that it will exactly touch the convexity of those
threads of the former, which are raised. Then, if the threads of the
latter web are sunk while the others are raised, the two would be
entirely incorporated. But if this be only partially done, that is, at
particular places, only those parts immediately operated upon will be
affected by the action of the apparatus. If the carpet is a two-coloured
pattern, as black and red, and if upon the upper surface, as extended in
the loom, red flowers are to be represented upon a black ground, then
all those species of design paper which are coloured may be supposed to
represent the red, and those which are vacant the black. Then counting
the spaces upon the paper, omit those which are vacant, and cord those
which are coloured, and the effect will be produced. But as the two webs
are to be raised alternately, whatever is corded for the first handle
must be passed by for the second, and _vice versâ_; so that the one will
form the flower, and the other the ground.
The board by which the simples are regulated appears at F. D shows the
weights.
CARTHAMUS, or safflower (carthamus tinctorius), (_Carthame_, Fr.;
_Färber distel_, Germ.), the flower of which alone is used in dyeing, is
an annual plant cultivated in Spain, Egypt, and the Levant. There are
two varieties of it--one which has large leaves, and the other smaller
ones. It is the last which is cultivated in Egypt, where it forms a
considerable article of commerce.
Carthamus contains two colouring matters, one yellow and the other red.
The first alone is soluble in water; its solution is always turbid: with
re-agents it exhibits the characters usually remarked in yellow
colouring matters. The acids render it lighter, the alkalies deepen it,
giving it more of an orange hue: both produce a small dun precipitate,
in consequence of which it becomes clearer. Alum forms a precipitate of
a deep yellow, in small quantity. The solution of tin and the other
metallic solutions cause precipitates which have nothing remarkable in
them.
The yellow matter of carthamus is not employed; but in order to extract
this portion, the carthamus is put into a bag, which is trodden under
water, till no more colour can be pressed out. The flowers, which were
yellow, become reddish, and lose in this operation nearly one half of
their weight. In this state they are used.
For extracting the red part of carthamus, and thereafter applying it to
stuff, the property which alkalies possess of dissolving it is had
recourse to, and it is afterwards precipitated by an acid.
The process of dyeing consists, therefore, in extracting the colouring
matter by means of an alkali, and precipitating it on the stuff by means
of an acid. It is this fecula which serves for making the rouge employed
by ladies.
As to this rouge, the solution of carthamus is prepared with
crystallised carbonate of soda, and it is precipitated by lemon juice.
It has been remarked that lemons, beginning to spoil, were fitter for
this operation than those which were less ripe, whose juice retained
much mucilage. After squeezing out the lemon juice, it is left to settle
for some days. The precipitate of carthamus is dried at a gentle heat
upon plates of stone-ware; from which it is detached and very carefully
ground with talc, which has been reduced to a very subtile powder, by
means of the leaves of shave-grass (_presle_), and successively passed
through sieves of increasing fineness. It is the fineness of the talc,
and the greater or less proportion which it bears to the carthamus
precipitate, which constitute the difference between the high and low
priced rouges.
Carthamus is used for dyeing silk, poppy, _nacarat_ (a bright
orange-red), cherry, rose colour, and flesh colour. The process differs
according to the intensity of the colour, and the greater or less
tendency to flame colour that is wanted. But the carthamus bath, whose
application may be varied, is prepared as follows:
The carthamus, from which the yellow matter has been extracted, and
whose lumps have been broken down, is put into a trough. It is
repeatedly sprinkled with cendres gravelées (crude pearl ashes), or soda
(barilla) well powdered and sifted at the rate of 6 pounds for 120 lbs.
of carthamus; but soda is preferred, mixing carefully as the alkali is
introduced. This operation is called _amestrer_. The _amestred_
carthamus is put into a small trough with a grated bottom, first lining
this trough with a closely woven cloth. When it is about half filled, it
is placed over the large trough, and cold water is poured into the upper
one, till the lower becomes full. The carthamus is then set over another
trough, till the water comes from it almost colourless. A little more
alkali is now mixed with it, and fresh water is passed through it. These
operations are repeated till the carthamus be exhausted, when it turns
yellow.
After distributing the silk in hanks upon the rods, lemon juice, brought
in casks from Provence, is poured into the bath till it becomes of a
fine cherry colour; this is called turning the bath (_virer le bain_).
It is well stirred, and the silk is immersed and turned round the
skein-sticks in the bath, as long as it is perceived to take up the
colour. For _ponceau_ (poppy colour), it is withdrawn, the liquor is run
out of it upon the peg, and it is turned through a new bath, where it is
treated as in the first. After this it is dried and passed through fresh
baths, continuing to wash and dry it between each operation, till it has
acquired the depth of colour that is desired. When it has reached the
proper point, a brightening is given it by turning it round the sticks
seven or eight times in a bath of hot water, to which about half a pint
of lemon juice for each pailful of water has been added.
When silk is to be dyed _ponceau_ or flame colour, it must be previously
boiled as for white; it must then receive a slight foundation of
annotto, as explained in treating of this substance. The silk should not
be alumed.
The _nacarats_, and the deep cherry colours, are given precisely like
the _ponceaux_, only they receive no annotto ground; and baths may be
employed which have served for the _ponceau_, so as to complete their
exhaustion. Fresh baths are not made for the latter colours, unless
there be no occasion for the poppy.
With regard to the lighter cherry-reds, rose colour of all shades and
flesh colours, they are made with the second and last runnings of the
carthamus, which are weaker. The deepest shades are passed through
first.
The lightest of all these shades, which is an extremely delicate flesh
colour, requires a little soap to be put into the bath. This soap
lightens the colour, and prevents it from taking too speedily, and
becoming unevenly. The silk is then washed, and a little brightening is
given it, in a bath which has served for the deeper colours.
All these baths are employed the moment they are made, or as speedily as
possible, because they lose much of their colour upon keeping, by which
they are even entirely destroyed at the end of a certain time. They are,
moreover, used cold, to prevent the colour from being injured. It must
have been remarked in the experiments just described, that the caustic
alkalies attack the extremely delicate colour of carthamus, making it
pass to yellow. This is the reason why crystals of soda are preferred to
the other alkaline matters.
In order to diminish the expense of the carthamus, it is the practice in
preparing the deeper shades to mingle with the first and the second bath
about one fifth of the bath of archil.
Dobereiner regards the red colouring matter of carthamus as an acid, and
the yellow as a base. His carthamic acid forms, with the alkalies,
colourless salts, decomposed by the tartaric and acetic acids, which
precipitate the acid of a bright rose-red. Heat has a remarkable
influence upon carthamus, rendering its red colour yellow and dull.
Hence, the colder the water is by which it is extracted, the finer is
the colour. Light destroys the colour very rapidly, and hitherto no
means have been found of counteracting this effect. For this reason this
brilliant colour must be dried in the shade, its dye must be given in a
shady place, and the silk stuffs dyed with it must be preserved as much
as possible from the light. Age is nearly as injurious as light,
especially upon the dye in a damp state. The colour is very dear,
because a thousand parts of carthamus contain only five of it.
In preparing the finest rouge, the yellow colouring matter being
separated by washing with water, the red is then dissolved by the aid of
alkali, and is thrown down on linen or cotton rags by saturating the
solution with vegetable acid. The colour is rinsed out of these rags,
dissolved anew in alkalis, and once more precipitated by lemon juice.
The best and freshest carthamus must be selected. It is put into linen
bags, which are placed in a stream of water, and kneaded till the water
runs off colourless. The bags are then put into water soured with a
little vinegar, kneaded till the colour is all expelled, and finally
rinsed in running water. By this treatment the carthamus loses nearly
half its weight. 6633 cwts. of safflower were imported into the United
Kingdom in 1835, of which 2930 cwts. were retained for internal
consumption.
CASE-HARDENING, is the name of the process by which iron tools, keys,
&c., have their surfaces converted into steel.
Steel when very hard is brittle, and iron alone is for many purposes, as
for fine keys, far too soft. It is therefore an important desideratum to
combine the hardness of a steely surface with the toughness of an iron
body. These requisites are united by the process of case-hardening,
which does not differ from the making of steel, except in the shorter
duration of the process. Tools, utensils, or ornaments, intended to be
polished, are first manufactured in iron and nearly finished, after
which they are put into an iron box, together with vegetable or animal
charcoal in powder, and cemented for a certain time. This treatment
converts the external part into a coating of steel, which is usually
very thin, because the time allowed for the cementation is much shorter
than when the whole substance is intended to be converted. Immersion of
the heated pieces into water hardens the surface, which is afterwards
polished by the usual methods. Moxon in his _Mechanic Exercises_, p.
56., gives the following receipt for case-hardening:--“Cow’s horn or
hoof is to be baked or thoroughly dried and pulverised. To this add an
equal quantity of bay salt; mix them with stale chamber-lye or white
wine vinegar: cover the iron with this mixture, and bed it with the same
in loam, or enclose it in an iron box: lay it on the hearth of the forge
to dry and harden: then put it into the fire, and blow till the lump
have a blood-red heat, and no higher, lest the mixture be burnt too
much. Take the iron out, and immerse it in water to harden.” I consider
the vinegar to be quite superfluous.
I shall now describe the recent application of prussiate (ferrocyanate)
of potash to this purpose. The piece of iron, after being polished, is
to be made brightly red-hot, and then rubbed or sprinkled over with the
above salt in fine powder, upon the part intended to be hardened. The
prussiate being decomposed, and apparently dissipated, the iron is to
be quenched in cold water. If the process has been well managed, the
surface of the metal will have become so hard as to resist the file.
Others propose to smear over the surface of the iron with loam made into
a thin paste with a strong solution of the prussiate, to dry it slowly,
then expose the whole to a nearly white heat, and finally plunge the
iron into cold water, when the heat has fallen to dull redness. See
STEEL.
CASHMERE or CACHEMERE, a peculiar textile fabric first imported from the
kingdom of Cashmere, and now well imitated in France and Great Britain.
The material of the Cashmere shawls is the downy wool found about the
roots of the hair of the Thibet goat. The year 1819 is remarkable in the
history of French husbandry for the acquisition of this breed of goats,
imported from the East under the auspices of their government, by the
indefatigable courage and zeal of M. Jaubert, who encountered every
fatigue and danger to enrich his country with these valuable animals,
aided by the patriotism of M. Ternaux, who first planned this
importation, and furnished funds for executing it at his own expence and
responsibility. He placed a portion of the flock brought by M. Jaubert,
at his villa of Saint Ouen, near Paris, where the climate seemed to be
very favourable to them, since for several successive years after their
introduction M. Ternaux was enabled to sell a great number of both male
and female goats. The quantity of fine fleece or down afforded by each
animal annually, is from a pound and a half to two pounds.
The wool imported into Europe comes by the way of Casan, the capital of
a government of the Russian empire upon the eastern bank of the Wolga;
it has naturally a grayish colour, but is easily bleached. Its price a
few years back at Paris was 17 francs per kilogramme; that is, about 6
shillings the pound avoirdupois. The waste in picking, carding, and
spinning, amounts to about one third of its weight.
The mills for spinning Cachemere wool have multiplied very much of late
years in France, as appears from the premiums distributed at the
exposition of 1834, and the prices of the yarn have fallen from 25 to 30
per cent. notwithstanding their improved fineness and quality. There is
a fabric made with a mixture of Cachemere down and spun silk, which is
becoming very general. One of the manufacturers, M. Hindenlang,
exhibited samples of Cachemere cloth woven with yarn so fine as No. 130
for warp, and No. 228 for weft.
Messrs. Pollino, brothers, of Paris, produced an assortment of Cachemere
pieces from 22 to 100 francs the yard, dyed of every fancy shade. Their
establishment at Ferté-Bernard occupies 700 operatives, with an
hydraulic wheel of 60 horse power.
The oriental Cashmere shawls are woven by processes extremely slow and
consequently costly; whence their prices are very high. They are still
sold in Paris at from 4,000 to 10,000 francs a piece; and from 100 to
400 pounds sterling in London. It became necessary therefore either to
rest satisfied with work which should have merely a surface appearance,
or contrive economical methods of weaving, to produce the real Cachemere
style with much less labour. By the aid of the draw-loom and still
better of the Jacquard loom, M. Ternaux first succeeded in weaving
Cachemere shawls perfectly similar to the oriental in external aspect,
which became fashionable under the name of French Cachemere. But to
construct shawls altogether identical on both sides with the eastern,
was a more difficult task, which was accomplished only at a later period
by M. Bauson of Paris.
In both modes of manufacture, the piece is mounted by reading-in the
warp for the different leaves of the heddles, as is commonly practised
for warps in the Jacquard looms. The weaving of imitation shawls is
executed, as usual, by as many shuttles as there are colours in the
design, and which are thrown across the warp in the order established by
the _reader_. The greater number of these weft yarns being introduced
only at intervals into the web, when the composition of the pattern
requires it, they remain floating loose at the back of the piece, and
are cut afterwards, without affecting in the least the quality of the
texture; but there is a considerable waste of stuff in the weaving,
which is worked up into carpets.
The weaving of the imitation of real Cachemere shawls is different from
the above. The yarns intended to form the weft are not only equal in
number to that of the colours of the pattern to be imitated, but besides
this, as many little shuttles or pirns (like those used by embroiderers)
are filled with these yarns, as there are to be colours repeated in the
breadth of the piece; which renders their number considerable when the
pattern is somewhat complicated and loaded with colours. Each of these
small bobbins or shuttles passes through only that portion of the flower
in which the colour of its yarn is to appear, and stops at the one side
and the other of the cloth exactly at its limit; it then returns upon
itself after having crossed the thread of the adjoining shuttle. From
this reciprocal intertexture of all the yarns of the shuttles, it
results, that although the weft is composed of a great many different
threads, they no less constitute a continuous line in the whole breadth
of the web, upon which the lay or batten acts in the ordinary way We
see therefore that the whole art of manufacturing this Cachemere cloth
consists in avoiding the confusion of the shuttles, and in not striking
up the lay till all have fulfilled their function. The labour does not
exceed the strength of a woman, even though she has to direct the loom
and work the treddles. Seated on her bench at the end opposite to the
middle of the beam, she has for aids in weaving shawls from 45 to 52
inches wide, two girl apprentices, whom she directs and instructs in
their tasks. About four hundred days of work are required for a
Cachemere shawl of that breadth. For the construction of the loom, see
JACQUARD.
In the oriental process all the figures in relief are made simply with a
slender pirn without the shuttle used in European weaving. By the
Indians the flower and its ground are made with the pirn, by means of an
intertwisting, which renders them in some measure independent of the
warp. In the Lyons imitation of this style, the leaves of the heddles
lift the yarns of the warp, the needles embroider as in lappett weaving,
and the flower is united to the warp by the weft thrown across the
piece. Thus a great deal of labour is saved, the eye is pleased with an
illusion of the loom, and the shawls cost little more than those made by
the common fly shuttle.
Considered in reference to their materials, the French shawls present
three distinct classes, which characterise the three fabrics of Paris,
Lyons, and Nimes.
Paris manufactures the French Cachemere, properly so called, of which
both the warp and the weft are the yarn of pure Cachemere down. This web
represents with fidelity the figures and the shades of colour of the
Indian shawl, which it copies; the deception would be complete if the
reverse of the piece did not show the cut ends. The Hindoo shawl, also
woven at Paris, has its warp in spun silk, which reduces its price
without impairing its beauty much.
Lyons however has made the greatest progress in the manufacture of
shawls. It excels particularly in the texture of its Thibet shawls, the
weft of which is yarn spun with a mixture of wool and spun silk.
Nimes is remarkable for the low price of its shawls, in which spun silk,
Thibet down, and cotton, are all worked up together.