Chapter II: BLEACHING of =Linen=:--Linen may be bleached in a similar way to (10)

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.

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.

_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.

2. Prussiate of potash, 3 parts; sal-ammoniac, 1 part; mix.

3. Sal-ammoniac and bone-dust, of each 2 parts; prussiate of potash, 1 part. (See _above_.)

=CA'SEIN.= _Syn._ CA'SEUM, CA'SEIN, LACTALBU'MEN, ALBUMEN OF MILK. The nitrogenous principle of milk. Cheese made from skimmed milk and well pressed is nearly pure casein. (Liebig.)

_Prep._ 1. The curd obtained by adding dilute sulphuric acid to milk is well washed and dissolved in carbonate of soda. It is allowed to stand for 24 hours, to let the oil rise to the surface, and when this is properly skimmed off, the casein is precipitated by an acid. The process is repeated a second time, and the coagulum digested with alcohol and ether, and dried. With all these precautions the casein still contains some saline matter which cannot be removed.

2. Milk is coagulated by hydrochloric acid, and the curd then well washed with dilute acid, and finally with pure water. The curd so prepared is dissolved by digestion at 110° Fahr., with a large quantity of water; the solution, after filtration, is coagulated with carbonate of ammonia; the coagulum is washed with water, ether, and alcohol, and finally dried.

_Prop., &c._ Coagulated casein is readily dissolved by the alkalies and alkaline carbonates. The most remarkable property of casein is its coagulation by certain animal membranes, as in the process of cheese-making with rennet. See LACTARIN.

=CASKS.= The care and management of casks is an important affair in a large establishment. It is found that they last longest when stored either in a dry situation, or in one uniformly very moist. Continual variations from the one to the other speedily rot them. As soon as casks are emptied they should be bunged down quite air-tight, with as much care as if they were full, by which means they will be preserved both sweet and sound. Should any of the hoops become loose they should be immediately driven up tight, which will at once prevent the liability of their being lost or misplaced, as well as the casks fouling or becoming musty from the admission of air. For this purpose those out of use should be occasionally hauled over and examined.

Numerous plans are adopted for CLEANING and PURIFYING CASKS, among which are the following:--

1. Wash them well out with oil of vitriol, diluted with an equal weight of water.

2. Wash them first with a little chloride of lime and warm water, and then with water soured with oil of vitriol.

3. Match them with sulphur, or with sulphur mixed with a little saltpetre.

4. Unhead them and whitewash them with fresh milk of lime, made pretty strong. This plan is commonly followed for brewers' vats.

5. Remove the heads, and char the insides of the staves by the aid of a fire of shavings kindled within them.

6. A simpler, safer, and more effectual method of charring them than the last is to wash the dry casks out with strong oil of vitriol (sp. gr. 1·854). This not only purifies the surfaces of the staves, but penetrates into all the cracks, some of which might escape the action of the fire.

7. Steam has lately been applied to the insides of casks with great advantage. High-pressure steam is driven in at the bung-hole, at the same time that the cask is violently agitated (a heavy chain having been previously put into it), until all the dirt and bad smell is removed.

8. A lye of pearlash or soda, mixed with milk of lime, as well as strong hot brine, and other similar liquors, have been adopted by some persons, and are highly spoken of.

9. The coopers boil the staves for gin casks in a strong lye of alum before placing them together, to prevent their colouring the spirit, but washing with oil of vitriol is a better plan.

10. Some persons fill musty casks with water and add 3 or 4 lbs. of coarsely powdered fresh burnt charcoal, and agitate well for a few days.

11. Wash with bisulphite of lime.

_Obs._ In all the above processes the greatest care must be taken to scald or soak and well rinse out the casks after the treatment described. See BREWING UTENSILS, SPOROKTON, MATCHES, &c.

=CAS'SAREEP.= The expressed juice of the sweet cassava, concentrated by heat and flavoured with aromatics. It is used in the West Indies as a condiment. (See _below_.)

=CAS'SAVA.= A poisonous shrub cultivated in the West Indies and in many parts of South America for the sake of the starchy matter contained in its roots. It belongs to the natural order Euphorbiaceæ, and is known to botanists under the names _Manihot utilissima_ (Pohl), _Janipha manihot_ (Humboldt), and _Jatropha manihot_ (Linn.), the former being that now generally adopted. The name "bitter cassava" is commonly given to it in the West Indies, to distinguish it from another species of the same genus, _Manihot aipi_ (Pohl), which, from having no poisonous properties, is named the "sweet cassava." The roots of both species yield the starch, but those of the poisonous plant are the richer.

The roots, after being well washed and scraped, are rasped or grated, and the pulp thus formed is subjected to strong pressure, to expel the poisonous juice which it contains. The compressed pulp is next thoroughly dried over the fire, being constantly stirred the whole time, by which any remaining portion of the noxious juice is either volatilised or decomposed. It now forms CASSAVA MEAL. When it is further prepared by grinding, it forms FINE CASSAVA MEAL or CASSAVA FLOUR. When the compressed pulp is baked on a hot plate, it forms CASSAVA BREAD or CASSAVA CAKES, the flavour of which greatly resembles that of Scotch oat-cakes. See TAPIOCA.

=CAS'SIA.= In _botany_, a genus of the natural order Leguminosæ, including several important medicinal plants. The "purging cassia," _Cassia fistula_ (Linn.), produces pods containing a soft, blackish pulp. (See _below_, also SENNA.)

=Cassia Pulp.= _Syn._ CASSIA PRÆPARA'TA, CASSIÆ PULPA (B. P.), L. _Prep._ The cassia (pods or fruit), broken lengthwise, are macerated in sufficient distilled water to cover them for six hours, constantly stirring; and the purified pulp strained through a hair sieve, and evaporated to the consistence of a confection in a water bath.--_Dose._ As a mild laxative, 1 to 2 dr.; as a purgative, 3/4 oz. to 1-1/2 oz.

=CAS'SOLETTES= (Scented). See PASTILLES and PERFUMERY.