2. Oil of Caraway, 1 dr.; sugar, 1 lb.

=Candy, Diges'tive.= _Syn._ LIVE-LONG CANDY. _Prep._ 1. Rhubarb and

bicarbonate of soda, of each 1 dr.; ginger, 1/2 dr.; cinnamon, 20 gr. (all

in fine powder); heavy magnesia, 1 oz.; powdered sugar, 2 oz.; mucilage of

tragacanth, q. s. to form a lozenge mass; to be divided into small squares

of 18 or 20 gr. each.

2. As the last, but adding finely powdered caraways, 1 dr.; oil of

caraway, 15 drops; and sugar, 1 oz. Both are used as heartburn and

digestive lozenges.

=Candy, Gin'ger.= _Prep._ 1. From ginger (in coarse powder), 3 oz.;

boiling water, 1-1/4 pint; macerate in a warm place for 2 hours, strain,

add lump and moist sugar, of each 5 lbs., and boil to a candy.

2. Ginger (in very fine powder), 1 oz.; powdered sugar, 2 lbs.; syrup, q.

s. to make a paste. Stomachic and carminative.

For various sweetmeats which might come under the head of CANDY, see

CONFECTIONS, DROPS.

=CANKER.= This disease consists in a depraved condition of that part of

the sensitive foot of the horse which secretes the horny frog and sole. It

mostly occurs in coarsely-bred animals, and is the result of filth, damp,

and bad ventilation. The treatment consists in first removing all loose

horn, and allowing all pent-up matter to escape; the exuberant

granulations must be carefully cut away, and the parts then washed with a

tepid lotion of sulphate or chloride of zinc; after drying the surface

dust it with oxide of zinc; apply tow dipped in a mixture of tar and lime,

and "keep it in firm contact with the parts by means of a leather sole or

strips of hoop iron underneath a shoe lightly tacked on. Dress in this

manner daily, keeping up the dry pressure for a week." (Finlay Dun.)

=CAN'NON METAL.= See GUN METAL.

=CANTHAR'IDES.= _Syn._ SPANISH FLIES, BLISTERING F., LYT'TÆ; CANTHAR'IS,

B. P. The _Cantharis vesicatoria_ of Latreille, commonly known as the

Spanish fly, is an insect of the order Coleoptera; it abounds in the south

of France, Spain, and Italy; and has spread into Germany and the south of

Russia. When alive it exudes a strong fetid and penetrating odour.

_Pur., &c._ These insects should be preserved in well-closed bottles or

tin canisters. The addition of a few drops of oil of cloves, or of strong

acetic acid, or even of a few cloves in substance, will preserve them

unchanged for a length of time in closed vessels. The best proof of their

goodness is the smell. The powder is constantly adulterated. The plan of

the wholesale druggists is to sort out the most worthless flies for

powdering, and to compensate for their deficiency of vesicating power by

adding 1 lb. of euphorbium to every 12 or 13 lbs. of flies. When a

superior article is required, liquorice powder is added (4 or 5 lbs. to

every 14 lbs.), along with about 1 lb. of euphorbium, and sufficient blue

black or charcoal to turn the yellow of the liquorice to a greenish

colour. The best mode of detecting this adulteration is by the microscope.

It should be borne in mind that only those flies which have attained their

full growth possess blistering properties. The immature or undersized

insects are destitute of epigastric power.

_Ant._ An emetic of sulphate of zinc, followed by the stomach-pump, if

necessary. The vomiting may be promoted by copiously drinking warm bland

diluents, such as broth, linseed tea, milk, &c. Friction on the spine,

with volatile liniment and laudanum, and the subsequent administration of

draughts containing musk, opium, and camphorated emulsion, have been

strongly recommended.

_Tests._ By the microscope very minute particles may be discovered in the

stomach and intestines, on a post-mortem examination. Orfila thus found

particles of cantharides in a body that had been interred nine months.

_Uses, &c._ Spanish flies are used externally to raise blisters, and

internally as a stimulant and diuretic, generally in the form of tincture.

In excess they produce strangury, bloody urine, satyriasis, delirium,

convulsions, and death. See TINCTURES, VESICANTS, &c.

=CANTHARI'DIN.= C_{5}H_{12}O_{2}. Isomeric with picrotoxin. This substance

is found in, and is the vesicating principle of, the Spanish fly, Chinese

blistering fly, and other coleopterous insects. _Prep._ Pulverised

cantharides are allowed to remain in contact for 24 hours with twice their

weight of chloroform, in a displacement apparatus. The chloroform is then

drained off, and finally displaced by alcohol, and the solution is left to

evaporate. The cantharidin crystallises out, saturated with green oil. In

order to purify the cantharidin it is laid on bibulous paper, which

absorbs the greater part of the oil, and then crystallised out of a

mixture of alcohol and chloroform. (Procter.)

_Prop._ Prismatic crystals, melts at 200° C., volatilises in white fumes,

which strongly irritate the eyes, nose, and throat, and condenses in

rectangular prisms. Cantharidin is insoluble in water, but soluble in

alcohol, ether, chloroform, acetic acid, and in the fixed and volatile

oils. Its solution in any of the liquids above mentioned possesses

vesicating properties, which, however, is not exhibited by solid

cantharidin.

=CAOUT'CHOUC.= _Syn._ INDIA RUBBER, ELASTIC GUM. India rubber is the

concrete juice of the _Ficus elastica_, _Siphonia elastica_, the _Urceola

elastica_, and many other tropical plants. The fresh milky juice is spread

over moulds of unbaked clay, and is then exposed to the heat and smoke of

a fire, or torches, to dry it, whence it derives its dark colour.

Successive coats of juice are laid on, and the operation of drying

repeated until the bottles acquire sufficient thickness. When it has

become thoroughly hard and dry, the clay is beaten out. In this form it is

commonly imported.

_Prop., &c._ The general properties of india rubber, as well as its

numerous applications, are well known. The fresh juice has a cream-like

appearance and consistence, is coagulated by heat, and is miscible with

water, alcohol, and wood naphtha; sp. gr. 1·012 to 1·041; it yields from

18% to 45% of solid caoutchouc, either by heat or evaporation. By

excluding it from the air it may be preserved unchanged for a considerable

period.

Solid caoutchouc has a sp. gr. ranging between ·919 and ·941; it melts at

248° Fahr. into a viscid mass, which does not again harden on cooling; it

is unaltered by chlorine, hydrochloric acid, sulphurous acid, fluosilicic

acid, ammonia, caustic alkaline lyes (even when boiling), and most similar

substances; nitric acid and sulphuric acid act on it only by long contact

when concentrated. Some specimens of caoutchouc are harder than gutta

percha itself, and equally inelastic, whilst others never perfectly

solidify, but remain in a condition resembling that of birdlime or

printers' varnish.

The best solvents of caoutchouc are rectified sulphuric ether (which has

been washed with water to remove alcohol and acidity), chloroform,

bisulphide of carbon, a mixture of bisulphide of carbon and absolute

alcohol (94 of the first to 6 or 7 of the last), and caoutchoucin. All

these liquids dissolve india rubber rapidly in the cold, and leave it

unaltered on evaporation. The first two are, however, too expensive to be

generally employed. The others have a disagreeable odour, but are much

cheaper than the rest, and possess the advantage of leaving the film of

caoutchouc in a firmer and stronger condition than other solvents.

Pyrogenous oil of turpentine is another cheap and good solvent. Benzol,

rectified mineral or coal-tar naphtha, crude petroleum, and oil of

turpentine dissolve india rubber by long digestion and trituration (with

heat), otherwise they merely form with it a glutinous jelly that dries

very slowly and imperfectly, leaving it much reduced in hardness and

elasticity. The fats and fixed oils also readily dissolve caoutchouc (with

heat), forming permanently glutinous solutions or pastes; so also do most

of the volatile oils, but the solutions with the majority of them dry with

difficulty.

One of the most remarkable properties of india rubber is the great amount

of heat which is disengaged during its condensation by pressure or in the

exercise of its elasticity. During the process of kneading the raw

caoutchouc in the "masticators," the cold water thrown in to reduce the

temperature soon becomes boiling hot. When no water is added, a

temperature so high is often reached as to occasion the melting of the

rubber. This is particularly the case during the process of "dry kneading"

with quick-lime. A tube 2-1/4 inches in diameter, impactly secured, was

subjected to a force of 200 tons. The result was a compression amounting

to 1-10th; great heat was evolved, and the excessive elasticity of the

substance caused a fly-wheel weighing five tons to recoil with alarming

violence. Mr Brockedon states that he succeeded in raising the temperature

of an ounce of water 2° in about fifteen minutes by collecting the heat

evolved by the extension of a small thread of caoutchouc. He refers this

effect to the change in specific gravity, and contends that the heat thus

produced is not due to friction, because the same amount of friction is

occasioned in the contraction as in the extension of the substance, and

the result of this contraction is to reduce the caoutchouc thus acted upon

to its original temperature.

The edges and surfaces of india rubber are readily and perfectly joined by

mere contact and intense pressure. On the small scale the edges may be

moistened with ether, naphtha, oil of turpentine, or some other solvent,

or by long boiling in water, and immediately pressed tight together and

held in contact for some time.

Elastic tubes are readily formed of india rubber by cutting it into

uniform slips of proper thickness and winding them round rods of polished

glass or metal, so that the edges are in close contact or "overlapping." A

piece of tape is then wound round outside it, and the whole boiled in

water for 2 or 3 hours, after which time the edges will be found to be

sufficiently adherent. A better plan is to immerse the "rubber" in a

mixture formed of bisulphide of carbon, 95 parts, and rectified spirit, 5

parts, until it swells into a pasty mass, which may then be moulded into

any desired form or passed through the die of a tubing machine. For

chemical purposes, brewing, &c., vulcanised india-rubber tubing has now

taken the place formerly occupied by the unprepared material.

The once celebrated "Mackintoshes" are made by spreading two or more coats

of a paste made of caoutchouc and rectified coal-tar naphtha over the

surface of the stuff or cloth, and, when it has become partially dry,

pressing two such surfaces evenly together by passing the goods between a

pair of cylinders or rollers. The articles are then placed in a stove room

for the composition to harden, and to remove the odour of the naphtha. Of

late years vulcanised or mineralised rubber (coloured) has been used for

this purpose, and being spread on the outside of the stuff instead of the

inside forms an ornamental and thoroughly waterproof material.

India-rubber thread is prepared by stretching it (previously cut into

coarse filaments) to 5 or 6 times its length in boiling water or hot air,

in which state it is allowed to cool slowly. This process is repeated

again and again until it reaches 16,000 or 17,000 times its original

length, when it is glazed by agitating it with powdered sulphur or French

chalk. This thread is readily joined or "pieced," as it is called, by

paring the ends obliquely with a pair of scissors or a knife, and then

pressing the clean ends strongly together with the fingers. When the

coarse filaments from the cutting machine are simply stretched with the

moistened thumb and finger in the act of "reeling" to about 8 or 9 times

their length, they are said to be "inelasticated," and are ready to be

made into elastic braces, elastic web, and other like elastic tissues and

fabrics in the braiding machine.

=Caoutchouc, Vul'canised.= _Syn._ VULCANISED INDIA RUBBER, MINERALISED I.

R., SULPHURETTED I. R. The discovery of the singular action of sulphur and

the mineral sulphides on caoutchouc was made by Mr Charles Goodyear, of

New York, in 1842, at which date the manufacture of vulcanised india

rubber may be said to have commenced. In 1843 Mr Thomas Hancock patented a

process for vulcanised india rubber in these countries, founded on that of

Mr Goodyear. A sheet of caoutchouc immersed in melted sulphur absorbs a

portion of it, and at the same time undergoes important changes in many of

its leading characteristics. So prepared, it is no longer affected by

changes of temperature; it is neither hardened by cold nor softened by any

heat insufficient to destroy it. It loses its solubility in the solvents

of ordinary caoutchouc, whilst its elasticity is greatly augmented, and

has become permanent.

The same effect is produced when sulphur is kneaded into caoutchouc in a

masticator, or by means of powerful rollers, as well as when common

solvents (naphtha, spirit of turpentine, &c.) are charged with a

sufficient amount of sulphur in solution to become a compound solvent of

the rubber. In these cases articles may be made of any required form

before heating them for the change of condition technically termed

"vulcanisation." It is necessary, however, for this purpose that the form

should be carefully maintained both before and during the exposure to the

heat.

"A vulcanised solid sphere of 2-1/2 inches in diameter, when forced

between two rollers 1/4 inch apart, was found to maintain its form

uninjured. In fact, it is the exclusive property of vulcanised caoutchouc

to be able to retain any form impressed upon it, and to return to that

form on the removal of any disturbing force which has been brought to act

upon it." (Brockedon.)

Caoutchouc combines with from 12% to 15% of sulphur; the quantity of

sulphur added to the naphtha paste should not, therefore, exceed 10% or

12% of its weight.

The temperatures for vulcanisation by the common method range from 320° to

330°; and the period required is one hour or more, according to the

temperature. A much lower temperature is, however, sufficient if the

duration of the exposure is much extended or the compound mass is softened

with any of the common solvents of india rubber.

The process of sulphuring, or mineralisation, is differently conducted in

different manufactories. Under Mr Burke's patent, oxysulphide or amorphous

sulphide of antimony (formed by decomposing a solution of crude antimony

in a lye of potash or soda with hydrochloric acid) is employed. This

powder he combines with either india rubber or gutta percha, or mixtures

of them, by kneading in a "masticator" for 2 or 3 hours, and after strong

compression in a mould whilst still warm, he exposes the mass to a steam

heat ranging from 250° to 280° Fahr. The block, so prepared, is afterwards

cut into sheets, &c. The advantages possessed by the product are that it

possesses no unpleasant odour, nor does the sulphur effloresce on its

surface, as in ordinary vulcanised india rubber.

Under Mr Christopher Nickel's patent (1849) 1 part of sulphur is kneaded

with 6 parts of caoutchouc, and then pressed into moulds, as before. He

also vulcanises rubber by exposing it in a cylinder heated in a steam

jacket to the fumes of sulphur or to sulphuretted gases, given off from a

retort connected with the apparatus. The rubber thus prepared he next

subjects to hydraulic pressure in moulds, at a temperature ranging between

220° and 250° Fahr.

Small articles or sheets of india rubber may be extemporaneously

vulcanised at common temperatures by simple immersion, for a minute or

two, in a mixture of bisulphide of carbon, 97-1/2 parts, and protochloride

of sulphur, 2-1/2 parts; after which they must be well washed first in

weak alkaline lye, and next in pure water. Mr Parkes employs 100 instead

of 97-1/2 parts of the bisulphide. This method is termed "cold

sulphuring."

An excellent method of vulcanisation, recommended by Mr Parkes,

particularly applicable to small articles, consists in immersing them for

about 3 hours in a close vessel containing a solution of polysulphide of

potassium at 25° Baumé (sp. gr. 1·197), and of the temperature of 240°

Fahr. It is afterwards washed in an alkaline lye, then in pure water, and

dried.

Among the many applications of vulcanised india rubber those connected

with its elasticity and its enormous contractile power when extended are

particularly striking. Under Mr E. Smith's patent, "torsion springs" for

roller blinds, door springs, clock springs, carriage springs, &c., are

made of it. Mr Hodges, in another patent, has availed himself of the same

property as a new mechanical power. Short lengths of caoutchouc, which he

terms "vulcanised power purchases," are successively drawn down from or

lifted to a fixed bearing, and attached to any weight which it is required

to raise; when a sufficient number of these power purchases are fixed to

the weight, their combined elastic force lifts it from the ground. Thus,

10 purchases of the elastic strength each of 50 lbs. raise 500 lbs. Each

purchase is 6 inches long, and contains about 1-1/2 oz. of vulcanised

caoutchouc. These 10 purchases, if stretched to the limit of their

elasticity (not of their cohesive strength), will lift a weight exceeding

650 lbs.

The same principle has been applied to relieve and equalise the strain on

ships' cables, especially where several boats are towing one vessel; and

as a projectile force. A number of power purchases, attached to the barrel

of a gun constructed to project harpoons, will exert a power, if suddenly

relieved, proportioned to their aggregate forces. By similar contrivances

balls may be projected 200 yards or more, and a charge of No. 4 shot can

be thrown 120 yards. A bow, in which the string alone is elastic (the

reverse of the usual form), has been contrived which throws a 30-inch

arrow 170 yards.

The last great improvement in the manufacture of caoutchouc is the

discovery that by continuing the process of vulcanisation for a longer

time at an increased heat and under pressure, a hard black substance is

obtained, which can be turned in a lathe like ebony. This substance has

already been applied to an extraordinary number of uses. See VULCANITE.

An exceedingly useful combination of cork and india rubber has lately been

introduced. See KAMPTULICON.

=Caoutchouc, Facti''tious.= See OIL, CONSOLIDATED.

=CAOUT'CHOUCIN.= An extremely light fluid obtained by distilling india

rubber.

_Prep._ (Barnard's patent process.) A highly volatile fluid, discovered by

Mr Barnard. India rubber or caoutchouc, as imported, cut into small lumps,

containing about 2 cubic inches each, is thrown into a cast-iron still,

connected with a well-cooled worm-tub (any flat vessel with a large

evaporating surface will do, the entire top of which can be removed for

the purpose of cleaning it out); and heat is applied in the usual way,

until the thermometer ranges to about 600° Fahr., when nothing is left in

the still but dirt and charcoal. The dark coloured fetid oil which has

distilled over is next rectified along with 1/3rd its weight of water,

once or oftener; and at each rectification becomes brighter and paler,

until at about sp. gr. ·680 it is colourless, and slightly volatile. The

product is then shaken up with nitro-hydrochloric acid, or chlorine, in

the proportion of a 1/4 of a pint of the acid to 1 gallon of the liquid.

To enable the dirt to be the more easily removed from the bottom of the

still, common solder, to the depth of about 1/2 an inch, is thrown

in.--_Prod._ 80%.

_Prop., &c._ Mixed with alcohol, caoutchoucin dissolves gums and resins,

especially copal and india rubber, at the common temperature of the

atmosphere, and it speedily evaporates, leaving them again in the solid

state. It mixes with the oils in all proportions. It has been used in the

manufacture of varnishes, and for liquefying oil paints, instead of

turpentine. It is very volatile, and requires to be kept in close vessels.

According to the researches of Himly, Gregory, and Bouchardat, the

caoutchoucin of Barnard consists of several liquids, some of which have

the composition of olefiant gas, and others that of oil of turpentine.

=CA''PERS.= The flower buds of various species of _Capparis_, particularly

_C. spinosa_, caper tree, preserved in vinegar. They are chiefly imported

from Spain, Italy, and the south of France, where the caper tree is

largely cultivated for the purpose. The flower-buds are picked daily, and

thrown into a cask of strong pickling vinegar, until it becomes full, when

it is sold to the dealers by the collector. The former sort them into

different sizes by means of copper sieves, in a similar way to that

adopted for lead shot and gunpowder. In this way they are divided into

nonpareilles, capuchins, capotes, seconds, and thirds, of which the

former, or smallest, are regarded as the best; but much depends upon the

quality of the vinegar.

The bright green colour of capers, so much valued by the ignorant, arises

chiefly from the presence of copper derived from the sieves used in

sorting them. In many cases, copper coin, as sous and halfpence, are added

for the purpose. Thus the eye is gratified at the sacrifice of the

stomach, and an insidious poison introduced into the system, simply to

give an unnatural appearance to a condiment which tastes better without

it. See COPPER.

=CAPILLAIRE'.= [Fr.] Simple syrup, or a concentrated solution of sugar in

water, flavoured with orange-flower water, or some other similar aromatic.

The name was originally given to a mucilaginous syrup, prepared by adding

to an infusion of maiden-hair (_Adiantum capillus Veneris_) some sugar and

orange-flower water.

=CAP'NOMOR.= See KAPNOMOR.

=CAP'RIC ACID.= HC_{10}H_{19}O_{2}. _Syn._ RU'TIC ACID; ACIDUM CAP'RICUM,

L. An acid discovered by Chevreul, and obtained by decomposing caprate of

barium with dilute sulphuric acid, or primarily by the saponification of

butter or cocoa-nut oil, when it appears combined with butyric, caproic

and caprylic acids. It is also procured by acting upon oleic acid or oil

of rue with nitric acid.

_Obs._ When butter is saponified with caustic potassa or soda, and the

resulting soap decomposed by adding an acid, in excess, and distilling the

mixture, the four acids above named pass over into the receiver, in

combination with water. The mixed acids may be separated by saturating

them collectively with baryta, and by taking advantage of the unequal

solubility of the newly formed barium salts. The less soluble portion

(equal to about 1/20th of the dry mass) contains capric and caprylic acid;

the larger and more soluble portion, butyric and caproic acid. On the same

plan the two groups are resolved into their separate acids. These acids

are deprived of their uncombined water by means of chloride of calcium. It

is advisable to employ the term rutic acid, as the older term is easily

confounded with caproic and caprylic.

_Prop._ Capric or rutic acid crystallises in fine needles, which fuse at

86° Fahr., giving out an odour resembling that of a goat. It is sparingly

soluble in boiling water.

_Prep._ (Miller.) Castor oil is saponified by means of potassa or soda,

and afterwards an excess of the hydrated alkali is added, amounting to one

half the oil used. The mass is heated in a retort, and an oily liquid

covered with water distils over. This oily liquid, which is the octylic

alcohol, is rectified several times with potassa until the residue is no

longer coloured brown.--_Prop._ A colourless liquid, of powerful aromatic

odour; insoluble in water, but dissolving readily in acetic acid, ether,

and alcohol. Its boiling point is 356° Fr., its sp. gr, ·823. The

caprylate of ethyl, erroneously termed caprylic ether, is a colourless

liquid, with an agreeable odour of pine-apples.

=CAPSAICIN.= Until the researches of Mr Thresh proved to the contrary the

active principle of the capsicum fruit, or cayenne pepper, and the one to

which it was thought it owed its acrid and pungent properties, was

believed to be an alkaloid, and was named capsicine in consequence. Mr

Thresh succeeded in obtaining an alkaloid from the capsicum, but this was

entirely wanting in acridity and pungency. Its discoverer states that

capsaicin occurs only in the pericarp of the fruit. The details of the

process by which it may be obtained are given in the 'Year Book of

Pharmacy' for 1876-77, from which it will be seen that the substance may

also be procured by preparing a strong tincture of capsicum, and

submitting it to dialysis. Capsaicin when cautiously heated to 138° F.,

melts to a transparent oily fluid, and if then allowed to cool rapidly, it

becomes solid, assuming a crystalline condition in doing so. It

volatilises at 240° F., without suffering decomposition. Strong nitric

acid acts violently on it, decomposing and dissolving it. The crystals

dissolve very readily in ether, amylic, alcohol, acetic ether, benzine,

and fixed oils, and still more readily in alcohol, and in rectified and

proof spirit. In turpentine and carbon disulphide it dissolves much more

slowly. It is not affected by boiling for some considerable time in dilute

sulphuric acid, and the acid liquor shows no signs of glucose.

A specimen of capsaicin which Mr Thresh believes to have been in a pure

condition was sent to Dr Flückiger's laboratory for analysis, and Dr Buri,

by whom the combustion was made, reports that it gave the following

composition:--C_{19}H_{14}O_{2}, a result which Mr Thresh found to agree

very fairly with some capsaicin derived from a specimen fruit obtained

from a different source from that sent to Dr Flückiger. Administered

internally in doses of the 1/25th of a gram, capsaicin gave rise to

violent griping and purging; and when a lotion consisting of one part

diluted with forty of glycerin and spirit was placed on the arm, it soon

gave rise to such pain, and caused so much inflammation, that the lint

which was wetted with the solution had to be removed very shortly after

being applied.

=CAP'SICUM.= [L. and Eng.] _Syn._ CHIL'I, RED PEPPER. A genus of plants

belonging to the natural order Solanaceæ, species of which yield the

fruits which are used to form Cayenne pepper and Chili vinegar. The

officinal capsicum of B. P. is the fruit of the species _C. fastigiatum_.

See PEPPER, TINCTURES, VINEGARS.

=CAP'SULES.= This term is now commonly applied to small egg-shaped or

spherical vessels, in which medicines are placed, for the purpose of

covering their nauseous taste at the time of swallowing them. They are

commonly made of gelatin, mixtures of sugar and gelatin, or animal

membrane.

=Capsules, Gel'atin.= _Prep._ 1. By dipping the bulbous extremity of an

oiled metallic rod into a strong solution of gelatin. When the rod is

withdrawn, it is rotated, in order to diffuse the fluid jelly equally over

its surface. As soon as the gelatinous film has partially hardened, it is

removed from the mould and placed on pins, furnished with suitable heads,

and fixed on a cork table. When sufficiently dry, the capsules are placed

upright in little cells, made in the table to receive them, and the liquid

with which they are to be filled is then introduced by means of a small

glass tube. They are next closed by dropping some of the melted gelatin on

the orifice of each. Six parts of gelatin, and one part sugar, are now the

common proportions.

2. (Simonin.) Oval balls of wax, of the requisite size, are prepared by

pouring wax, into a wooden mould, consisting of two parts, and arranged

for the reception of a row of these balls. These are afterwards stuck on

iron needles, affixed to rods of convenient size, in rows. The balls are

now uniformly coated all at once by dipping in the usual manner, then

removed from the needles, and are next placed with the needle holes

downwards, on a gently heated plate, when the wax flows out, and a round

capsule is left behind.

=Cap'sules, Gel'atin and Su'gar.= _Prep._ (Giraud.) Gelatin, 6 parts;

solution of gum and simple syrup, of each 1 part; water, 5 parts; melt in

a water bath, remove the scum, and proceed as before.

=Capsules, Glut'en.= These, which form the subject of a French patent, are

said to be formed of the gluten of wheat flour, a substance which is

insoluble, although softened, by water. We have placed these capsules for

twenty-four hours in warm water, and found them, at the expiration of that

time, still unbroken, the enclosed medicine being completely enveloped.

The mode of preparation is kept secret.

=Capsules, Mem'branous.= _Syn._ ORGAN'IC CAPSULES. From gut-skin moistened

and stretched over an oiled bulb of glass or metal, and filled in the

common way. These have been patented, but they do not appear to be an

improvement on the common capsule of gelatin.

_Obs._ The common capsules usually hold about 10 or 12 gr. of balsam of

copaiba. Those of the shops in nine cases out of ten, are filled with

adulterated copaiba, and at least 4-5ths of them are filled with train oil

or linseed oil, to which a few drops only of the balsam are added.

Balsam of copaiba (capivi) and oil of cubebs, or a mixture of them, castor

oil and cod-liver oil, are the substances most usually administered in

this way. _Baccæ copaiferæ factitiæ_ are officinal in the Ph. Castr. Ruth.

Ratier has proposed to grease them and administer them per anum. Ricord

has strongly recommended capsules of copaiba, coated with extract of

rhatany, as much superior to the common ones of copaiba alone, in the

treatment of gleet and gonorrh[oe]a. They may be easily prepared by either

of the following methods:

1. By immersing, for an instant, the common capsule in a mixture of

extract of rhatany (newly prepared from the root), 3 parts; syrup of moist

sugar, 1 part; mucilage of gum Arabic, 1 part; melted together in a water

bath.

2. By forming the bodies of the capsules with the above mixture or

composition, instead of with gelatin, and then following the same

manipulations as for the manufacture of the common gelatin capsules.

These capsules are said to sit well upon the stomach, the tone of which

they contribute to improve, and to act with greater certainty than those

made of copaiba and gelatin alone.

=CAR'AMEL.= A dark-brown substance obtained by heating sugar. It is formed

during the roasting of all materials containing sugar, such as coffee and

malt. It is much used for colouring soups, wines, spirits, and other

liquids.

=Caramel, Crude.= _Syn._ SPIRIT COLOURING, BURNT SUGAR. _Prep._ From cane

sugar, by heating it to from 410° to 428° Fahr., as long as aqueous vapour

is formed; dissolving the product in water, and concentrating the solution

by evaporation.

=Caramel, Pure.= _Prep._ 1. (Graham.) Crude caramel, obtained as above, is

placed on a parchment-paper dialyser. The undecomposed sugar and certain

intermediate compounds diffuse out with considerable facility, and what

ultimately remains on the dialyser possesses five times the colouring

power of the original crude caramel, weight for weight. See DIALYSIS.

2. (Peligot.) Add strong alcohol to a filtered aqueous solution of crude

caramel until it ceases to produce a precipitate; collect the precipitate,

which is caramel, on a filter, wash with alcohol, and dry. Graham

recommends that the product should be dissolved and precipitated four or

five times, or till the mass thrown down, from being plastic at first,

becomes pulverulent.

3. (J. J. Pohl.) Cane sugar is heated in a spacious metallic vessel by

means of an oil bath to 410° or 419° Fahr. as long as aqueous vapours

escape, the mass being occasionally stirred with a spatula. The mass is

then finely powdered and digested with alcohol for two or three hours; the

digestion is repeated until the fluid no longer tastes bitter.

_Prop._ A solution containing 10% of purified caramel is gummy, and forms

a tremulous jelly on standing. Evaporated in vacuo, it dries up into a

black shining mass soluble in water; but if the solution be evaporated to

dryness by the heat of a water bath, the whole matter is rendered

insoluble in hot or cold water. A very small proportion of caramel

suffices to give a rich sepia tint to water.

=CAR'AT.= A weight of 4 grains used in weighing diamonds, which are spoken

of as of so many carats weight. Among assayers, a carat is a weight of 12

grains; but more commonly a proportional weight or term, representing the

number of parts of pure gold in 24 parts of the alloy; pure gold being

spoken of as of 24 carats fine. It is commonly the 24th part of the "assay

pound," and is nominally subdivided into 4 assay grains, and these again

into quarters. See ASSAYING.

=CAR'AWAY.= _Syn._ CARAWAY SEED; SE'MENA CARUI, L.; CARUI, B. P. The fruit

of the _Carum Carui_ (Linn.), an umbelliferous plant, common in England

and other parts of Europe. These fruits, commonly called "seeds," form an

agreeable and useful aromatic and carminative, and are especially esteemed

in the flatulent colic of children. They are also largely employed as an

adjuvant or corrective in various officinal preparations; and as a

flavoring ingredient in cakes, biscuits, cordials, confectionery, &c. See

ESSENCES.

=CARBAZOT'IC ACID.= See PICRIC ACID.

=CARBOL'IC ACID.= H.C_{6}H_{5}O. _Syn._ PHENYLIC ACID, PHENIC ACID,

PHENOL, PHENYLIC ALCOHOL, HYDRATE OF PHENYLE, HYDRATED OXIDE OF PHENYLE. A

powerful antiseptic substance obtained from coal-tar oil.

_Prep._ Crude, heavy coal oil is agitated with milk of lime, allowed to

stand, and the aqueous portion separated from the undissolved oil and

decomposed by hydrochloric acid. The oily liquid obtained is purified by

distillation.

1. Crude coal oil is distilled in a retort furnished with a thermometer,

and the portion which passes over when the heat ranges between 300° and

400° Fahr., is collected apart, and mixed with a hot saturated solution of

caustic potassa; after standing for some time, a semi crystalline pasty

mass forms, from which the supernatant liquid is decanted; the pasty mass

is now agitated with a small quantity of water until dissolved; the

solution thus formed separates into two portions, the denser of which

contains carbolate of potassa; this being separated by decantation, is

decomposed by hydrochloric acid. The solution of carbolic acid which rises

to the surface is digested with chloride of calcium, to remove water, and

purified by distillation; the distillate, by refrigeration, furnishes

crystals of the acid, which must be drained, dried, and preserved from the

air.

2. From salicylic acid. Mix intimately together equal weights of salicylic

acid and powdered glass; introduce the mixture into a good German retort,

and heat on a sand bath, gradually raising the heat till it becomes red

hot at the bottom. The vapour is condensed in any convenient receiver. If

the materials are perfectly dry, it solidifies to a mass of crystals as

soon as it condenses, but if there be a trace of water present it remains

liquid. The slower it distils over the lighter will be the colour, while

if a high temperature be employed it comes over nearly black. It may be

rendered colourless and anhydrous by rectification over quick-lime.

Of late years the manufacture of carbolic acid has increased to a great

extent, and is generally found in a pale yellow clear solution, instead of

as a dark hazy liquid. The pure anhydrous acid is in long, colourless,

prismatic crystals, often, however, on keeping turning a beautiful pink,

rose, or crimson, and which rapidly deliquesce in moist air, becoming

converted into a colourless refractive liquid, having a faint odour of

roses and tar. At 95° F. they become an oily liquid, having an odour and

taste like creosote. Sp. gr. 1·065, boiling point 370° F. Exposed to the

air the crystals absorb moisture and liquefy. The acid is slightly soluble

in water, but freely soluble in glycerin, alcohol, and ether. Carbolic

acid is poisonous, and is a powerful antiseptic.

_Tests._--About a grain of hypochlorite of calcium, added to a little

aqueous solution of carbolic acid, placed in a test-tube, produces after

agitation, the addition of a few drops of ammonia, and the application of

a gentle heat, a bright blue colour with a tinge of green. One drachm of

the acid if pure completely dissolves on being shaken with half a pint of

warm water.

_Uses._ The extraordinary antiseptic properties of carbolic acid have long

been known, but its extended use has been delayed, owing to the difficulty

experienced in obtaining it in considerable quantities. It is now,

however, principally owing to the labours of the late Dr F. Crace Calvert,

produced on a large scale, and this chemist has proposed its application

to many valuable purposes. As a medical agent it seems to have all the

useful properties of creosote in an exalted degree, with some peculiar

actions of its own, and is being applied with marked success in the

Manchester Royal Infirmary and similar institutions, in cases of chronic

diarrh[oe]a, obstinate vomiting (even after creosote has failed), and as a

disinfecting wash for ill-conditioned ulcers and gangrenous sores. It has

been said to have been used with marked success internally as a remedy

for hooping-cough. It has also been applied successfully in cases of

foot-rot, a disease which annually carries off large numbers of sheep. It

has been employed for the preservation of gelatin solutions and

preparations of size made with starch, flour, and similar materials, and

of skins and other animal substances. It appears to act strongly as an

antiferment, and Dr Calvert states that it is one of the most powerful

preventives of putrefaction with which he is acquainted. Commercial

creosote is frequently nothing more than hydrated carbolic acid.

Professor Lister, of Edinburgh, adopting the germ theory of putrefaction,

and regarding the putrid discharge from wounds as the result of the

presence of atmospheric organisms which find a suitable nidus in the

decomposing animal tissue exposed by the wound, seeks to exclude the

access of these germs by the use of antiseptics, particularly of carbolic

acid, the destructive action of which on living organisms is well known.

He applies to the wounds dressings of gauze previously prepared with

carbolic acid, additionally using as a lotion the acid, well diluted with

water; whilst during the dressing of the wounds and the performance of

surgical operations carbolic acid is diffused in the form of spray into

the surrounding atmosphere with the object of destroying the germs

floating in it.

_Antidotes._--Calcined magnesia, or bicarbonate of soda, in milk after

short intervals. In the absence of these, chalk, soap and water, or the

plaster from the ceiling. Olive oil additionally. More than fifty per

cent. of the carbolic acid manufactured is used for the purpose of

preparing the following pigments and dye materials:--

1. Picric acid. 2. Phenyl brown. 3. Grenat soluble. 4. Coralline. 5.

Azuline. These will be found described under TAR COLOURS.

=CAR'BON.= C. _Syn._ CARBO'NIUM, CAR'BO, L.; CHARBON, Fr.; KOHLENSTOFF,

Ger. An elementary or simple non-metallic solid body, very widely diffused

through nature. Its purest and rarest form is that of the diamond. Nearly

pure, it occurs very abundantly in the forms of graphite and anthracite.

In combination with oxygen, as carbonic acid, it exists in the atmosphere

and in the waters of most springs, also in limestone, marble, chalk, and

dolomite. Combined with hydrogen, it enters largely into coal, peat, and

lignite. It is an essential constituent of organic matter, and hence it

has been termed the "organic element." Charcoal, lamp-black, and coke, are

more or less pure forms of carbon. By strongly igniting lamp-black in a

covered crucible the element is obtained sufficiently pure for most

chemical purposes.

It is best obtained purest by burning a jet of pure olefiant gas in an

atmosphere of pure chloride, collecting the amorphous carbon deposited,

and igniting in vacuo at a red heat.

Forms several chlorides, sulphides, &c., of which the following are the

chief:--

=Carbon, Protochloride of.= Obtained from the sesquichloride by subliming

it repeatedly through a tube filled with fragments of glass heated to

redness. A transparent colourless liquid, with aromatic odour.

=Carbon, Sesquichloride of.= C_{2}Cl_{6}. Obtained by exposing Dutch

liquid with chlorine, in a glass vessel, to the direct rays of the sun,

taking care to renew the chlorine as long as it is absorbed. The liquid is

ultimately converted into the sesquichloride of carbon, which is a white

crystalline, volatile substance.

=Carbon, Tetrachloride of.= _Syn._ BICHLORIDE OF CARBON. It may be

obtained by passing chlorine (desiccated by being made to pass through a

tube wetted with strong sulphuric acid), through a bottle containing

bisulphide of carbon, and afterwards through a porcelain tube, wrapped in

sheet copper, and filled with fragments of broken porcelain, maintained at

a red heat, by a charcoal or gas furnace, and condensing the product in a

bottle surrounded by ice. A mixture of tetrachloride of carbon and

chloride of sulphur is thus obtained. By shaking this mixture with

solution of potash, the chloride of sulphur is decomposed and dissolved,

whilst the tetrachloride of carbon separates, and falls to the bottom. The

upper layer having been poured off, the tetrachloride may be purified by

distillation.

Tetrachloride of carbon is a colourless liquid, having a sp. gr. 1·6, and

boiling at 172° F. It is insoluble in water, but dissolves in alcohol and

ether. Its vapour, diluted with air, is employed as an anæsthetic.

=Carbon, Oxychloride of.= COCl_{2}. _Syn._ CHLO'ROCARBON'IC ACID, PHOSGENE

GAS, CHLORIDE OF CARBONYL. Equal measures of carbonic oxide and chlorine

are exposed to the direct rays of the sun; they combine, and become

condensed to half their volume. It is a colourless, suffocating gas, which

is immediately decomposed by water into carbonic and hydrochloric acids.

=Carbon, Sulphide of.= CS_{2}. _Syn._ BISULPHIDE OF CARBON, CARBON

DISULPHIDE, SULPHURET OF CARBON. Bisulphide of iron (iron pyrites), 5

parts, and fresh dry charcoal, 1 part, are heated together in a stoneware

retort, furnished with a glass tube, having the end bent, and passing

nearly to the bottom of a bottle or receiver filled with pounded ice. The

bisulphide of carbon collects at the bottom of the receiver, and is then

purified from adhering moisture and sulphur by distilling it, at a low

temperature, from fused chloride of calcium.

By passing the vapour of sulphur over fragments of charcoal, heated to

bright redness in a porcelain tube, and collecting the product as before.

Sulphide of carbon is best manufactured by means of Peroncele's apparatus

figured in the accompanying drawing.

[Illustration]

A is a fire-clay gas retort supported on the fire-clay block B; E and E

are openings, one being that of a porcelain tube firmly cemented into the

cover of A, serving for the introduction of sulphur; the other opening is

for the introduction of pieces of coke, with which before the operation

commences the retort is filled. The vapours of the sulphide of carbon pass

through the tubes H and I into the vessel J, wherein part of the sulphide

is condensed, and flows through K into the flask L, filled with water,

thence through M into O, finally being run off by the tap N. Any vapours

not condensed in J pass through P P into the worm T, the condensed

sulphide being collected in S. The crude sulphide is rectified by

redistillation over zinc or perchloride of mercury by means of a steam or

water bath. If the perchloride is employed it should remain in contact

with the crude sulphide for at least 24 hours before redistillation.

_Prop., Uses, &c._ A colourless, pungent, fetid liquid, having the sp. gr.

1·27. It is exceedingly volatile, boiling at 118·5° Fahr., and has never

been frozen. It is highly inflammable, burning with a pale-blue flame, and

giving off sulphurous and carbonic-acid gases. It freely dissolves sulphur

and phosphorus, and by spontaneous evaporation deposits the first in

beautiful crystals. The solution of phosphorus is much used in

electrotyping objects, which are coated with a conducting film by its

means. Its refractive power is remarkably high, and on this account it is

employed to fill hollow lenses for spectroscopes and other optical

instruments. It produces intense cold by its evaporation. A spirit

thermometer, having its bulb covered with cotton, if dipped into this

fluid and suspended in the air, rapidly sinks from 60° to 0°, and if put

into the receiver of an air-pump it will fall to -81° Fahr. A mixture of

sulphide of carbon and solid carbonic anhydride forms almost the most

powerful frigorific agent known. Sulphide of carbon is now prepared on the

large scale, and extensively employed as a solvent.

It is thus used for extracting from the cake of fruits and seeds the oil

remaining in them after they have been submitted to pressure. The sulphide

is subsequently separated from the oil by distillation. In Algiers it is

used for obtaining the essential oils contained in the rose, jessamine,

and lavender. It is also employed for dissolving the fat from bones, and

from the crude wool. Furthermore, it is an excellent solvent for

caoutchouc, as well as for the ordinary resins.

Its vapour is employed by agriculturists to kill the larvæ infesting

grain. Latterly, it has been employed as a disinfectant.

_a._ _Carbon Bisulphide as an Antiseptic._ By P. Zöller ('Deut. Chem. Ges.

Berl.,' ix, 1080-1084). The author has continued his experiments on this

subject with the object of determining (1) the minimum quantity of

bisulphide required, and (2) whether articles of food preserved by means

of it are fit for human consumption.

As regards the first point, he found that meat of all kinds, and even

entire animals, in quantities up to 20 kilograms, kept perfectly well for

several weeks in vessels of sheet zinc, into which 5 grams of carbon

bisulphide had been introduced, the meat being either simply hung on hooks

or wrapped in cloths and laid on perforated shelves in the vessels.

Probably a smaller quantity of the bisulphide would suffice. Meat also

kept well for 62 days in a vessel in which carbon bisulphide was liberated

by introducing potassium xanthate and dilute sulphuric acid. Freshly baked

bread, vegetables, and fruits of all kinds (asparagus, radishes, young

beans, cucumbers, strawberries, raspberries, currants, cherries, peaches,

apricots, lemons, &c.), and juices of fruits kept perfectly well in glass

vessels, into which carbon bisulphide has been introduced, in the

proportion of 5-10 drops for each litre of capacity.

Bread, vegetables, and fruit thus preserved are fit to eat after simple

exposure to the air, and cannot be distinguished by taste or other

qualities (except a slight loss of colour in some fruits) from fresh

bread, &c. Meat retains even after exposure to air the disagreeable odour

of carbon bisulphide. But besides this odour, which disappears on boiling

or roasting, the meat has a slight smell of the volatile fatty acids and

the taste of game. To most people, however, this taste is not unpleasant.

The presence of fatty acids is to be attributed to decomposition taking

place in the interior of the meat, and not preventable by the carbon

bisulphide, the function of which is merely to kill germs present in the

air or on the surface of substances submitted to its influence.

_b._ By Hugo Schiff ('Deut. Chem. Ges. Ber.,' ix, 828). Cocoons of

silkworms which had been killed by exposure to the vapours of carbon

disulphide underwent no change during six months' keeping in flasks in the

laboratory. The bodies of some pigs which had been used for physiological

experiments were put into a stoppered vessel with a few c. c. of carbon

disulphide in 1869, and have been perfectly preserved without

decomposition. The same result was obtained with a lizard 35-45

centimetres long, which had been suffocated accidentally in 1869, and was

bottled whole. In this case a small quantity of liquid collected at the

bottom of the vessel, and the green hue of the skin became a dirty greyish

green, but not the slightest putrefaction occurred. Similar results were

obtained with the intestines of poultry immersed in water in 1872 with a

little carbon disulphide, in a bottle with a greased stopper; with a lump

of beef weighing 200 grams; and with the body of a finch killed with

paraconine. The beef yielded a normal flesh fluid, and was eaten by a dog

without hesitation even after several months.

_Purification._--1. It is stated that the odour of sulphide of carbon can

be readily removed by allowing it to stand over mercury or corrosive

sublimate for some time, and then redistilling.

2. The following method by Kern is stated by him to be the best for

purifying sulphide of carbon:--The impure product is well mixed in a tall

glass vessel with some lead nitrate, and with a small quantity of metallic

lead. When the salt turns dark the liquid is poured into another vessel

with a fresh quantity of the lead salt; and so on until the salt remains

nearly white while mixed with the liquor. The sulphide of carbon is then

placed in a retort, and distilled over into a well-cooled receiver.

3. M. Yvon proposes a process which consists in adding copper turnings to

the sulphide; no slaking is necessary. The sulphide soon becomes nearly

colourless, and loses its usually unpleasant odour. Miller says reduced

copper produces the same result.

Carbon sulphide is employed therapeutically in doses of 2 drops, gradually

increased to 5, as a sudorific in rheumatism. It is also dropped (40 to 50

drops) on the part, to promote the reduction of strangulated hernia.

Externally, it is employed in liniments for rheumatic pains.

=CAR'BONATE=, a salt in which the hydrogen of (hypothetical) carbonic acid

(H_{2}CO_{3}) is replaced by a metal or other basic radical.

_Prep., &c._ The processes by which the commercial carbonates and many

others are prepared are described under the respective bases. Most of the

earthy carbonates are found abundantly in nature. In general the salts of

this class may be formed by adding an alkaline carbonate to a salt of the

metal in solution by double decomposition.

_Prop._ The carbonates of the alkalies are soluble in water; those of the

other bases are for the most part insoluble, except the water is highly

charged with carbonic acid. From most of them carbonic anhydride or

anhydrous carbonic acid can be easily expelled by heat.

_Tests._ The carbonates are easily distinguished by the following

reactions:--They dissolve with effervescence in hydrochloric acid and in

most other acids; in some cases a gentle heat is required to promote the

disengagement of the gas.--The gas evolved in the last, passed into lime

water and baryta water, occasions white precipitates, which redissolve in

acids with effervescence, and after the solution has been boiled are not

reprecipitated by liquor of ammonia.--Chloride of calcium and chloride of

barium give white precipitates in solutions of the neutral alkaline

carbonates, but in solutions of the alkaline bicarbonates only after

ebullition; and the precipitates are readily soluble with effervescence in

acetic acid.

_Estim._ The quantity of the metal in an alkaline or earthy carbonate may

be easily determined by the ordinary volumetric methods of alkalimetry

(which _see_), and the quantity of carbonic acid, by the method of

Fresenius and Will (see ALKALIMETRY). The apparatus figured on next page,

or preferably that shown in the article on ALKALIMETRY, may be used

instead of the more complicated contrivance of the German chemists.

A weighed sample of the carbonate to be examined is placed in the flask

_a_ along with a little water, and the small tube, _b_, filled with either

sulphuric or hydrochloric acid, is carefully introduced. The cork, with

its chloride of calcium tube, _d_, is then fitted to the flask, and the

whole apparatus very accurately weighed.

On inclining the apparatus the acid escapes over the side of the small

tube, and mixing with the liquor in the flask, expels the carbonic

acid of the carbonate, which is then dried by passing over the chloride of

calcium. After effervescence has ceased heat should be applied to the

bottom of the flask, until it be filled with steam, to expel the carbonic

gas it contains. The loss of weight gives the weight of the carbonic acid

gas that was contained in the sample. The quantity of carbonic acid in the

carbonates of the metals that do not contain water may be determined by

heating them to redness in a platina crucible.

[Illustration: _a_, Flask containing the sample of carbonate for

examination, stopped by a closely fitting cork, through which passes the

bent tube _c_.

_b_, A small tube, sufficiently long to maintain a slanting position

without falling, filled with sulphuric or hydrochloric acid.

_c_, A bent tube, connecting the flask with _d_.

_d_, Horizontal tube, filled with small fragments of fused or dried

chloride of calcium, with a fine orifice at the extremity _e_.]

=CARBONIC ACID.= H_{2}CO_{3}. True carbonic acid has not yet been obtained

in any satisfactory condition, although the solution of carbonic anhydride

(often called carbonic acid), or anhydrous carbonic acid, is generally

regarded as such. It forms with bases an important series of salts, called

the carbonates, by double decomposition.

=CARBONIC ANHYDRIDE.= CO_{2}. _Syn._ CARBONIC ACID, CARBON DIOXIDE, FIXED

AIR, CHOKE DAMP; ACIDE CARBONIQUE, Fr.; KOHLEN SÄURE, Ger. A compound

formed by the chemical union of carbon and oxygen.

_Hist._ Van Helmont recognised carbonic acid as a peculiar gas. Dr Black,

in 1757, proved that it was a constituent of limestone, and gave it the

name of fixed air; he also showed that the causticity of alkalies depended

on its absence. Bergmann first described it as an acid, applying to it the

term aërial acid. Lavoisier, in 1776, established its true nature, and

gave it the name it now bears. Faraday, in 1823, by pressure at an

extremely low temperature, reduced carbonic acid to a liquid, and a few

years later Thiloria and Brunel obtained it in the solid form.

_Nat. Hist._ Carbonic acid is a constituent of the atmosphere, its

presence being essential to the existence of vegetable life on the globe.

It issues from the earth in many situations, as the Grotto del Cane in

Italy, the Valley of Poison in Java, and near the Lake of Laach in

Germany. It gives to many mineral springs their sparkling brilliancy, and

is held in solution by all natural waters. Combined with the bases, lime

and magnesia especially, it exists in large quantities in the crust of the

earth. It is the chief product of combustion, and one of the products of

fermentation. It is always being exhaled by animals in the process of

respiration, and in smaller quantities by plants at night or in the shade.

It forms the terrible "choke-damp" or "after-damp" of the coal mines. It

is the gas disengaged during the effervescence of soda water and other

aërated drinks, and the cause of the freshness of newly-drawn beer.

_Prep._ Hydrochloric acid, 1 part, diluted with water, 4 or 5 parts, is

poured upon fragments of white marble, previously placed in a suitable

generating apparatus.[237]

[Footnote 237: A large flask, provided with a bent glass tube for

conveying the gas, and a tube-funnel for introducing the acid, is the most

convenient form of apparatus. A tubulated retort may be used, but the

generating flask or bottle is to be preferred.]

Carbonic acid is rapidly evolved, and may be collected, with some loss,

over water in the pneumatic trough. If required dry, the gas must be

passed over fragments of fused chloride of calcium, placed in a large

tube, or through a small quantity of concentrated sulphuric acid, and

collected by displacement or over mercury.

From oil of vitriol, 1 part; water, 6 parts; and chalk or whiting, 1-1/4

part; mixed in a suitable vessel, applying agitation.

_Prop._ Under ordinary conditions carbonic acid is a colourless,

non-inflammable, irrespirable gas, possessing a slightly pungent odour,

and an acidulous taste. Water absorbs its own volume of this gas, and by

pressure may be made to take up enormous quantities, forming carbonated or

aërated water. Its sp. gr. is 1·520; hence it may be poured from one

vessel to another like water. By a pressure of thirty atmospheres at 32°

Fahr. it is liquefied, the pressure required decreasing as the temperature

gets lower. At -94° Fahr. it solidifies into a vitreous transparent mass.

Carbonic acid, even when greatly diluted with air, cannot be inhaled

without insensibility following. An atmosphere containing more than its

natural quantity of gas (1 part in 2500 parts by measure) acts upon the

system as a narcotic poison; hence the danger of over-crowded rooms. It is

a non-supporter of combustion, at once extinguishing a lighted candle,

gas-jet, or even a piece of burning phosphorus, when these are placed in a

jar of the gas.

_Tests._ It feebly reddens litmus paper, extinguishes the flame of a

burning taper, and forms a white precipitate in aqueous solutions of lime

and baryta, which is soluble in acetic acid. By the last test a very small

quantity of this gas may be easily detected in the atmosphere of rooms,

&c. A lighted candle is generally used to test an atmosphere suspected to

contain carbonic acid: but it is found that air that will support

combustion will contain sufficient of this gas to cause insensibility.

_Ant., &c._ The patient should be immediately removed into the open air,

and placed on his back with the head slightly raised. Cold water should be

dashed over the body, hot water or mustard poultices applied to the feet,

and ammonia (carefully) to the nostrils. Brandy-and-water and other

stimulants may be administered. Continued friction on the surface of the

body is also very useful. If the patient has ceased to breathe artificial

respiration should be attempted. This may be done by gently pressing down

the ribs, and forcing up the diaphragm, and then suddenly withdrawing the

pressure. The inhalation of air, mixed with very little chlorine gas, has

also been recommended. Wells, cellars, or other underground apartments,

containing carbonic acid in poisonous quantities, may be freed from this

gas by pumping it out in the same way as water, observing to allow the

suction hose to fully reach the floor or bottom of the place. Fresh slaked

lime or milk of lime, copiously thrown in, will have a like effect, by

absorbing the gas. Free ventilation, whenever it can be established, is,

however, not only the cheapest, but the most efficient remedy. See

ASPHYXIA.

=CARBON'IC OXIDE.= CO. _Syn._ PROTOXIDE OF CARBON, CARBON MONOXIDE,

GA'SEOUS OXIDE OF CARBON; OXY'DUM CARBON'ICUM, L. A gaseous compound of

carbon and oxygen, containing less oxygen than is contained in carbonic

acid.

_Prep._ 1. From carbonic acid gas passed over fragments of charcoal,

heated to redness in a tube of porcelain or iron.

2. From crystallised oxalic acid, gently heated with 5 or 6 times its

weight of strong sulphuric acid in a glass retort.

3. From ferrocyanide of potassium in fine powder, and 8 or 10 times its

weight of concentrated sulphuric acid, heated together in a glass retort.

_Obs._ All the processes except the last give a mixture of carbonic acid

and oxide. It is therefore necessary to pass the gas through a caustic

alkaline solution or milk of lime to deprive it of carbonic acid. It may

then be passed over dried chloride of calcium, to deprive it of moisture.

It may be collected either over mercury or water, as the latter absorbs

very little of this gas.

_Prop._ Carbonic oxide is colourless, inodorous, neutral, inflammable, and

irrespirable. It is extremely poisonous, 1% mixed with air being

sufficient to cause dangerous drowsiness. The deaths produced by the

combustion of charcoal in close rooms are now attributed to this gas. The

antidotes, &c., are the same as for poisoning from inhaling carbonic acid.

=CAR'BUNCLE.= A larger sized and dangerous form of boil, attended by

extensive sloughing. The treatment consists in lancing, poulticing, and

the adoption of a generous diet, with wine and stimulants. The safer plan,

however, is to seek the advice of a medical man.

=CAR'BURETTED HY'DROGEN.= See HYDROGEN.

=CARD'AMOM.= _Syn._ CARD'AMUM; CARDAMO'MUM, B. P. The seed or fruit of the

_Elettaria Cardamomum_ forms the officinal cardamom. It is warm, pungent,

carminative, and stomachic, and is largely used as a condiment in the

East, and in Europe as an adjuvant in other medicines. Several kinds of

cardamoms used medicinally and as spices are produced by the genus

_Amomum_, belonging to the natural order Zingiberaceæ, the Ginger family.

=CARD'BOARD.= Cardboard, or sized pasteboard, is made of two to fifteen

sheets of sized paper, pressed and stained. There are varieties of

cardboard known as Bristol-board, London-board, the former being largely

used for water-colour drawings, mounting-board, ornamental board, &c.

=CAR'MINATIVES.= Medicines that allay flatulency and spasmodic pains.

Among the principal carminatives are ANISEED, CARAWAY SEED, CARDAMOMS,

CASSIA, CINNAMON, GINGER, PEPPERMINT, and the PEPPERS. To these may be

added ARDENT SPIRITS, and most of the AROMATIC ESSENCES and TINCTURES. See

MIXTURES, PATENT MEDICINES, &c.

=CAR'MINE.= _Syn._ CARMINE RED, VEGETABLE SCARLET; CARMI'NUM, L. A

beautiful red pigment prepared from the cochineal insect.

_Prep._ The preparation of carmine is little understood, but success in

its manufacture depends less on any mystery connected with the process

than on the employment of the purest water and the best materials, and the

exercise of moderate care, dexterity, and patience. The following forms

will produce carmine of the richest hues down to ordinary and common,

according to the skill possessed by the manipulator.

1. (_Madame Cenette's process._) Cochineal (in powder), 2 lbs., is boiled

in pure river water, 15 galls., for 2 hours, when refined saltpetre

(bruised), 3 oz., is added to the decoction, and the whole boiled for 3 or

4 minutes longer; salt of sorrel, 4 oz., is next added, and the boiling

again renewed for 10 or 12 minutes; the heat is now removed, and the

liquid allowed to settle for about 4 hours, after which time it is

decanted with a syphon into shallow plate-like vessels, and set aside for

three weeks. At the end of this time the film of mould which has formed on

the surface is dexterously and carefully removed, without breaking it or

disturbing the liquid beneath it. The remaining fluid is next very

carefully removed with a syphon, and the adhering moisture, as far as

possible, drained off, or sucked up with a pipette. The residuum, which is

the carmine, is dried in the shade, and possesses extraordinary lustre

and beauty.

2. (Alxon or _Langlois' process_.) Powdered cochineal, 1 lb., is boiled in

river water, 4 galls., for 10 minutes, when carbonate of soda, 3/4 oz.,

dissolved in water, 1 pint, is added, and the whole again boiled for 1/2

hour longer; when the decoction is cold, alum (in fine powder), 3/4 oz.,

is thrown in, and the liquid agitated rapidly until it is entirely

dissolved; after 20 minutes' repose it is decanted into another vessel,

and clarified by heating it with the whites of 2 eggs; the perfectly clear

liquid is then allowed to repose for 40 minutes or longer, when it is

decanted, and the carmine which it has deposited is collected, drained on

a filter, and dried on shallow plates covered with silver paper. The

product by either of the above processes varies from 9-1/2 to 10% on the

weight of the cochineal employed in them.

3. (_China_ or _Spirit process._) Cochineal, 1 lb., is boiled for 15

minutes, in water, 3 galls., powdered alum, 1 dr., is next added, and the

whole again boiled for 5 or 6 minutes; when the liquid has become cold,

the clear portion is decanted, and again heated, the solution of tin

(spirits of tin) cautiously dropped in until all the carmine is

precipitated; it is collected, drained, and dried, as before. _Prod._

1-1/2 oz.

3. (_French process._) From cochineal (in powder), 1 lb., boiled for 15

minutes, in water, 3 galls.; cream of tartar (in powder), 1 oz., is then

added, the boiling further continued for 10 minutes, and powdered alum

1-1/2 oz., thrown in; after another 2 minutes' boil the heat is withdrawn,

and in 5 or 6 minutes more the clear portion is decanted into porcelain

vessels, which are set aside until the carmine falls down.

4. (_German process._) Powdered cochineal, 1 lb., water, 4 galls.; boil 15

minutes, add powdered alum, 1 oz.; boil 3 minutes longer, remove the heat,

allow the liquor to settle for 5 minutes, pour off the clear portion into

porcelain or earthenware vessels, and set them aside for 3 or 4 days. The

carmine is found deposited on the bottom of the vessel, and must be now

carefully drained and dried, as before. The decanted liquor yields more

carmine by standing in fresh vessels. _Product._ About 1-1/2 oz.; besides

1/2 oz., or more, of an inferior quality obtained as a second deposit.

5. (_English process._) From cochineal, 1 lb., and carbonate of potash,

1/2 oz., boiled in water, 7 galls., for 15 minutes; the vessel is then

removed from the fire, and powdered alum, 1 oz., added; the liquor is then

well agitated and allowed to settle for about 15 minutes longer; the clear

liquid is next decanted into a clean copper, and isinglass, 1/2 oz.,

dissolved in water, 1 pint (and strained), added; as soon as a coagulum

forms upon the surface, the heat is removed, and the liquid is strongly

agitated with a bone or silver spatula, after which it is allowed to

repose for 20 or 30 minutes. The deposited carmine must be drained and

dried, as before.

_Obs._ The best black cochineal is generally used for the preparation of

carmine. For ordinary qualities spirits of tin (bichloride) is added to

the decoction as a precipitant, and the liquid being put into suitable

vessels (wash-hand basins answer very well), a deposit of carmine slowly

takes place. Neither exposure to solar light nor artificial heat is

advisable during the drying, but the latter must nevertheless be effected

with all possible expedition. Hence the finer shades of carmine can only

be successfully made during certain states of weather; as in very hot

weather the liquid rapidly sours or ferments, and the deposit is more or

less dissolved; whilst in dull, damp weather it is difficult to dry the

precipitate sufficiently, which is then apt to become mouldy, and to lose

colour. The researches of Pelletier and Caventou tend to show that the

solution of tin used as a precipitant should be at the maximum of

oxidation or chlorination, to produce the richest shades of carmine. That

first deposited is, in all cases, the most beautiful, and the quality

gradually deteriorates as the process proceeds. 6 or 7 dr. only of carmine

of the very finest quality can hence be obtained from 1 lb. of cochineal.

_Prop., &c._ Pure carmine is a very light, lustrous, scarlet powder,

entirely soluble in ammonia, a test by which its purity is readily

determined. Mr Warren De la Rue says the pure colouring principle of

cochineal is carminic acid. By digesting ammonia on carmine until all the

colour is taken up, filtering and adding acetic acid and alcohol, till the

whole is precipitated; and lastly, carefully washing the precipitate with

spirit of wine, at proof, and drying in the shade, carmine of the richest

and most lustrous hue may be obtained even from samples of inferior

quality.

_Uses, &c._ As a pigment in velvet and miniature painting, and for tinting

artificial flowers, and as rouge for the complexion. The powdered

cochineal (carmine grounds), from which the coloured liquor (liquid rouge,

carmine liquor) has been decanted, is used by the paper stainers, and both

are used in the preparation of carminated lake.

=Carmine, Blue.= See INDIGO.

=Carmine, Li'quid.= _Syn._ FLUID CARMINE, LIQUID ROUGE, CARMINE INK.

_Prep._ 1. A solution of carmine in ammonia water, or spirits of

hartshorn. Very rich and beautiful.

2. The residual liquor of the process of making carmine. Inferior. The

first is used in velvet and miniature painting, and for tinting artificial

flowers; the second for common purposes, as a stain or wash.

=Carmine, Pur'ple.= See MUREXIDE.

=CARMIN'IC ACID.= C_{14}H_{14}O_{8}. _Prep._ (W. De la Rue.) The powdered

insect, after treatment with ether to remove the fat, is digested in

water. The decoction of cochineal is precipitated by adding a solution of

acetate of lead, and the impure carminate of lead thus formed, after

being washed with water, is suspended in water, and decomposed by a stream

of sulphuretted hydrogen; the whole process is repeated with the decanted

solution so obtained; the second solution is then evaporated to dryness

(in vacuo over sulphuric acid), dissolved in absolute alcohol, digested on

some washed crude carminate of lead (to separate a little phosphoric

acid), and, lastly, mixed with ether (to precipitate some nitrogenised

matter); the residuum obtained by careful evaporation (in vacuo) is pure

carminic acid.

_Prop., &c._ A purple-brown mass, yielding a rich-red powder; it is freely

soluble in water and alcohol; slightly soluble in ether; and without

decomposition in oil of vitriol; it is feebly acid; its salts are termed

carminates, only two or three of which have been examined. According to Mr

De la Rue, this acid constitutes the pure colouring matter of cochineal.

=CARNAUBA ROOT.= The root of the _corypha cerifera_, a wax-bearing palm,

growing on the shores of the Rio Francisco, in Brazil. Dr C. Symes (see

'Pharmaceutical Journal,' 3rd series, v, 661) says:--Two bales of this

root have been imported into Liverpool, with the following remarks in

Portuguese:--"This root is recognised by the professor as an excellent

purifying agent, and has been successfully applied in the cure of various

diseases arising from impurity of the blood. We are indeed astonished that

it is not more widely known, as its therapeutic qualities, which are

worthy of full credence, rival those of sarsaparilla. The carnauba root

likewise has a diuretic power, and possesses unusual efficacy, in the cure

of acute and chronic blennorrh[oe]as. It is, furthermore, very cooling,

and displays a vigorous action in purifying the blood." Mr Cleaver, who

submitted the root to analysis, found it to contain very minute quantities

of an alkaloid, an acrid resinous body, a red colouring matter, a variety

of tannic acid, and a small portion of volatile oil.

=CAROBA.= The leaves of a tree belonging to the family _Bignoniaceæ_,

employed in Brazil as a diaphoretic, diuretic, and alterative tonic. Dr

Alt states that he has used them extensively, and with much success, in

old-standing cases of syphilitic eruptions, and after a course of

mercurial treatment. They are usually administered either in the form of

powder or decoction.

=CAROT'INE.= C_{18}H_{24}O. A crystalline, copper-red substance, obtained

from the root of the _Daucus carota_ (_sativa_) or garden carrot. It is

tasteless; odourless; neutral; fusible; inflammable; insoluble in ether

and water; slightly soluble in alcohol; and very soluble in the mixed and

volatile oils.

=CAR'PETS.= Consideration of cleanliness and economy demand a few words on

carpets and hearth-rugs. We are assured by an experienced person that

before proceeding to sweep a carpet, a few handfuls of waste tea-leaves

should be sprinkled over it (say some five or six minutes before). A stiff

hair broom or hair brush only should be employed unless the carpet be very

dirty, when a whisk or carpet-broom may be used first, followed by another

made of hair, to take off the loose dust. The frequent use of a stiff

"carpet-broom" (those made of cane or birch are here alluded to) soon

wears off the beauty of the best carpet. An ordinary clothes-brush, or a

clean one, resembling the dirt brush used for shoes, is best adapted for

superior carpets. When carpets are very dirty they should be cleaned by

shaking and beating. "If you must have a carpet, take it up two or three

times a year, instead of once. A dirty carpet literally infects the room:

if you consider the enormous quantity of organic matter from the feet of

people coming in, which must saturate it this is by no means surprising."

(Miss Nightingale.) In laying down carpets it is very advisable, at first,

to cover the floor beneath them with large sheets of thick paper, so as to

prevent dust from rising between the boards. Old drugget, sacking,

matting, or any similar substance, will effect the same purpose, and will,

moreover, materially increase the durability of the carpet, by preserving

it from the contact of the hard floor.

BRUSSELS CARPETS may be cleaned with ox-gall (1 pint to a pailful of

water), and a scrubbing-brush, and floor-cloth; afterwards rinsing them in

fresh water applied in the same way. They should be previously perfectly

freed from dust by beating, and should be nailed down before commencing

the above operations. Great care should be taken to rub them as dry as

possible with a clean dry floor-cloth. A small portion only should be done

at a time, and a dry windy day selected for the purpose. A carpet treated

in this manner will be greatly refreshed in colour, particularly the

greens.

KIDDERMINSTER CARPETS will scarcely bear the above treatment without

becoming so soft as to get speedily dirty again. This may in some measure

be prevented by brushing them over with a hot weak solution of size in

water, to which a little alum has been added. Curd soap, dissolved in hot

water, may be used instead of ox-gall, but it is more likely to injure the

colours if produced by false dyes. When there are spots of grease on the

carpeting they may be covered with curd soap, dissolved in boiling water,

and rubbed with a brush until the stains are removed, when they must be

cleaned with warm water as before. The addition of a little gall to the

soap renders it more efficacious. Some persons employ a mixture of soap,

fuller's earth, and turpentine, for the same purpose. Benzol rapidly

removes the grease stains, and may be advantageously substituted for

preparations of soap.

=CAR'RAGEEN.= _Syn._ I''RISH MOSS; CHONDRUS, L. The _Chondrus crispus_ of

botanists, a well-known alga or seaweed. It contains a large proportion of

a peculiar jelly, called carrageen'in or pect'in. This may be purified by

agitation with dilute alcohol and filtration. The jelly forms an agreeable

article of diet. It is used to a limited extent for thickening colours in

calico printing. In _medicine_, carrageen is used in the form of a jelly

and decoction as a demulcent, and is often prescribed in pulmonary

complaints. See FIXATURE, ALGÆ, PASTE, SYRUP.

=CAR'ROT.= _Syn._ CARO'TA, L. The seed is carminative and diuretic; the

expressed juice of the root is anthelmintic. Scraped raw carrot is

sometimes employed as a stimulant application to sore nipples; the boiled

root as a poultice to sores and tumours. As an article of food, unless

young and well dressed, carrots are rather indigestible. Carrots can be

kept for many months if the tops are cut out, and they are then placed in

damp sand.

_Analysis of Carrots._

Water 87·30

Albumenoids 0·66

Cellular tissue, gum, and

non-nitrogenous substance 2·56

Sugar 5·54

Fibre 3·20

Mineral matters ·74

------

100·00

=CAR'THAMIN.= C_{14}H_{16}O_{7}. _Syn._ PURE ROUGE, SAF'FLOWER CARMINE,

SAFFLOWER LAKE. The red colouring matter of _Carthamus tinctorius_ or

safflower, formerly much used as a dye, particularly in the form of pink

saucers for dyeing stockings.

_Prep._ 1. Safflower, exhausted by washing it with water (or with water

acidulated with acetic acid), is dried, coarsely pulverised, and the

powder digested in a weak solution of carbonate of sodium; pieces of clean

white cotton or calico are then immersed in the solution, and acetic acid

gradually added in slight excess; the cotton is next washed, dried, and

digested in a fresh quantity of dilute solution of carbonate of sodium,

and agitation employed until the whole of the colour is again dissolved;

the new solution is filtered and slightly super-saturated with citric acid

(or acetic acid); the carthamin, which falls down in rich carmine-red

flocks, is lastly washed with cold distilled water, and dried.

2. Washed safflower (dried and powdered), any quantity; aqueous solution

of carbonate of sodium (containing 15% of carbonate), q. s. to form a

thick paste; after some hours press out the red liquor, nearly neutralise

it with acetic acid, put in cotton as before, and add acetic acid in

slight excess; the next day remove the cotton and wash it in water holding

in solution 5% of carbonate of sodium, until the colour is dissolved out,

after which precipitate with citric acid, as before.

_Prop., &c._ An amorphous, brilliant, greenish powder; nearly insoluble in

water, soluble in alcohol, forming a gorgeous purple solution, and in weak

alkaline lyes giving an equally beautiful red one.

=CAR'THAMUS.= _Syn._ SAF'FLOWER. In _botany_, a genus of composite plants,

the most important species of which is _Carthamus tinctorius_, the

safflower. The florets of this yield a beautiful pink dye (see _above_),

and are sometimes used to adulterate hay saffron. The "cake saffron" of

the shops consists entirely of safflower and mucilage. The fruits,

commonly called "seeds," yield by expression the useful oil known in India

as Koosum oil.

=CARUM (PTYCHOTIS) AJOWAN.= Ind. Ph. _Syn._ AJWAIN or OMUM PLANT.

_Habitat._ Tropical Africa? Much cultivated in India.--_Officinal part._

The fruit (_Fructus Ptychotis_, _Ajwain fruit_). Occurs in the form of

minute umbelliferous fruits, which, examined with a lens, are seen to be

covered with prominent tubercles, extremely aromatic, evolving, when

rubbed, a strong odour resembling that of common thyme. Taste somewhat

bitter, and very pungent. Its virtues reside in a volatile

oil.--_Properties._ Valuable stimulant, carminative, and

antispasmodic.--_Therapeutic uses._ In flatulence, flatulent colic, atonic

dyspepsia, and diarrh[oe]a, it is a remedy of much value.

OIL OF AJWAIN, or OMUM (_Oleum Ptychotis_). The oil obtained by

distillation from the fruit. Recently prepared, colourless, but soon

acquires a yellowish tinge. It has the odour of the fruit, and an acrid

burning taste. Sp. gr. about 0·88.--_Dose_, 1 to 3 drops on sugar or in

emulsion.

AJWAIN, OR OMUM WATER (_Aqua Ptychotis_). Take of ajwain fruit, bruised,

20 oz.; water, 2 galls. Distil a gallon.--_Dose_, 1 to 2 fluid ounces. A

valuable carminative; also useful in disguising the taste of disagreeable

drugs, especially castor oil, and obviating their tendency to cause nausea

and griping.

=CARYOPH'YLLIN.= C_{10}H_{16}O. _Syn._ CLOVE CAMPHOR, CLOVE RESIN. A

crystalline substance, isomeric with ordinary camphor, which deposits from

oil of cloves in needles.

=CARYOPH'YLLUS.= See CLOVE.

=CASCARIL'LA.= _Syn._ CASCARILLÆ CORTEX (B. P.), L. The bark of _Croton

eleutheria_ or the seaside balsam, a tree growing in the Bahamas and

Jamaica. It is an aromatic bitter, stomachic, and tonic--_Dose_, 10 gr. to

30 gr., in the form of powder, infusion, or tincture; in diarrh[oe]a,

dysentery, dyspepsia, low fevers, intermittents, &c.

=CASCARIL'LINE.= _Syn._ CASCARIL'LINA. _Prep._ (Duval.) Cascarilla is

exhausted with cold water by percolation, precipitated with acetate of

lead, and the filtrate treated with sulphuretted hydrogen; the filtered

liquid, after agitation with animal charcoal and filtration, is gently

evaporated to dryness. The powder is redissolved in boiling alcohol and

crystallised by very slow or by spontaneous evaporation. It has a bitter

taste and acid reaction; its aqueous solution is unaffected by the ferric

salts and tincture of galls.--_Dose_, 1 to 3 gr.; in dyspepsia, &c.

=CASE-HARD'ENING.= _Syn._ STEEL SUR'FACING. The operation of giving a

surface of steel to iron goods. Tools, fire-irons, fenders, keys, &c., are

usually case-hardened.

_Process._ 1. The goods (finished in every respect but polishing) are put

into an iron box, and covered with animal or vegetable charcoal, and

"cemented" at a red heat for a period varying with the size and

description of the articles operated on: these, when taken out, are

hardened by plunging into water, or oil, if they are of a delicate nature.

2. (Moxon.) Cow's horn or hoof is baked or thoroughly dried and

pulverised; to this is added an equal quantity of bay salt, and the whole

is made into a paste with stale chamber-lye, or white wine vinegar; the

iron is covered with this mixture, and bedded in it, in loam, or inclosed

in an iron box. In this form it is laid on the hearth of the forge to dry

and harden, then it is put into the fire, and blown till the lump has a

blood-red heat (no higher). It is hardened as before.

3. Coat the goods with a paste made of a concentrated solution of

prussiate of potash and loam; then expose them to a strong red heat, and

when it has fallen to a dull red, plunge the whole into cold water.

4. The goods, previously polished and finished, are heated to a

bright-red, and rubbed or sprinkled over with prussiate of potash. As soon

as the prussiate appears to be decomposed and dissipated the articles are

plunged into cold water.

_Obs._ The process of case-hardening has been well conducted when the

surface of the metal proves sufficiently hard to resist a file. The last

two plans are a great improvement upon the common method. By the topical

application of prussiate of potash (ferrocyanide of potassium) any part of

a piece of iron may be case-hardened without interfering with the rest.

=Case-hardening Powders.= _Syn._ CASE-HARDENING COMPOSITIONS. 1. Prussiate

of potash, dried and powdered.