Part 93

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.