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CAOUTCHOUC MANUFACTURES. 



- i* plain, .. \i-n material, iiMtally made of bomp, some- 

 time* of flu, sometimes of mixture of both, and occasionally of lew- 

 known fibrous substances. It in a coarse and Ktrong fabric, used for 

 ail*, sacks, floor-cloth, tent*, 4c. All that need be stated concerning 

 it* manufacture will be found under FLOOR-CLOTH; SAII.-MAKIN.. ; 

 WKAVTXO. 



C A N /.i >N KT. hi mimic (cmuoiutta, Italian, a diminutive of cmuoiM, 

 or nuuoHO, a long), a short long, one that is brief compared with the 

 acred airs of the oratorio, or with the arie of the Italian opera. 

 Formerly the term was applied to vocal music in parts ; now it is 

 confined to songs for a single voice. 



CAOUTCHEN. [CAOUTCHOUC.] 



CAOUTCHIN. [CAOUTCHOUC.] 



CAOUTCHOUC (India-rubber, Gum-elastic) is the dried milky sap 

 of various plants. [INDIA-RUBBER, in NAT. HIST. Div.] The fresh 

 juice of the India-rubber tree in appearance closely resembles cow's 

 milk ; its taste is also somewhat similar, and it may be drunk without 

 producing any marked injurious effect. It has an acid reaction. 

 Allowed to stand for some time, it separates into two portions. Exposed 

 under the microscope, it is seen to consist of a number of small globules, 

 floating in a clear aqueous fluid ; the globules are the caoutchouc, and 

 fornithirty to forty per cent, of the fresh juice. 



Caoutchouc may be obtained in a pure state by frequently washing 

 the sap with water, or by dissolving the common gum in chloroform, 

 precipitating with alcohol, and drying at a temperature of 70 or 80. 

 It then has the appearance of gum arable. It* ultimate principles are 

 carbon and hydrogen, in the proportion of 87'2 of the former to 12'8 

 of the latter ( = CH 7 ). 



Caoutchouc has been known in Europe but little more than a century. 

 As it occurs in commerce it i* of a brownish colour, and has neither 

 taste nor odour. Specific gravity "920 to '960. It is unaltered by 

 exposure to the air ; is soft, flexible, and very elastic. It burns readily, 

 giving off much smoke. According to M. Payen, it is mainly composed 

 of two proximate principles. One, forming thirty to forty per cent., 

 perfectly taken up when caoutchouc is digested in solvents ; the other, 

 fifty to sixty per cent., only slightly soluble, but becoming very much 

 swollen under their influence, owing to the penetration of the solution 

 into the numerous pores which, under the microscope, are seen to 

 traverse caoutchouc in every direction. By carefully renewing the 

 solvent several times, these two principles may be separated from each 

 other ; in its highly extended state, however, the slightest agitation 

 break* up the insoluble one. It is in this way that ether, benzole 

 f MAHIM: GLUE], bisulphide of carbon, oil of turpentine, and other 

 essential oils, act upon caoutchouc. This porosity also explains the 

 cause of the increase in volume and weight that caoutchouc undergoes 

 when immersed in water, alcohol, and other liquids that exert no 

 chemical action whatever upon it. The soluble principle is softer, less 

 coloured, and much more adhesive than the insoluble portion, the 

 latter however is much superior in tenacity and elasticity. The best 

 solvent for caoutchouc is a mixture of six or eight part* of absolute 

 alcohol with one hundred part* of bisulphide of carbon. Concentrated 

 xiilphuric or nitric acids slowly attack and decompose caoutchouc ; 

 beyond this it is unaffected by acids, alkalies, chlorine, or chemical 

 agents generally ; properties which render it almost invaluable for 

 many purposes in the arts. 



When caoutchouc is heated it soon softens, and at about 250 melts 

 * into a liquid having the consistence of tar. It does not solidify on 

 cooling, but remain* fluid for many months. In this state it forms an 

 excellent lute fur pneumatic apparatus ; spread over a cork or stopper, 

 it effectually prevent* the escape of gases or liquids. Heated to near 

 600* caoutchouc boils, the greater part being converted into vapour. 

 which by proper refrigerating apparatus may be condensed into a liquid 

 having powerful solvent pro|wrties. By repeated rectification it may 

 be obtained colourless. It rapidly dissolves, without the aid of heat, 

 caoutchouc, copal, and the varnish resins generally. The boiling point 

 of this liquid varies extremely. By the aid of freezing mixtures, a 

 portion may be obtained which boils at about the freezing point of 

 water. .Specific gravity at 25* i* '830. A large quantity distils over 

 between 280 and 890*, and this, by repeated fractionation and purifi- 

 cation, assume* a tolerably constant boiling point of 340. Amongst 

 these liquids Ittryten, entmlchtu, and rupio* seem to be present. 



CaoHlchi* (C_H,) is the name given to the sulwtance just mentioned. 

 It specific gravity is '842. Va]mr density 4'461. 



It is almost insoluble in water, and inisciblc in all proportions with 

 alcohol, ether, and the fixed and essential oil*. It combine* with 

 hydrochloric and hydrobromic acids, and i* rcsinified by peroxide of 

 ' 



When a htrip of caoutchouc stretched to five times its length in 

 heated to 212* and allowed to cool slowly, it does not again contract 

 Advantage is taken of this fact in the manufacture of elastic cloth. A 

 trip ft f. .t long will thus by six successive operations yield a thread 

 15,8'25 feet in length. 



VuUaititnl Indui-riMer is obtained by causing sulphur to coinoine 

 with caoutchouc. This may be done by triturating the latter, softened 

 by digestion in naphtha, with ten to twenty per cent, of sulphur, and 

 netting the mixture to 320*. Another method is by immersing sheet* 

 of caoutchouc fur two or three hours in melted sulphur at tempera- 

 ture of 210*, snd then heating to 320*, when the vulcanisation imme- 



diately tokos place. A third process, accomplished without the aid of 

 heat, consist* in dipping the caoutchouc into bisulphide of carbon con/ 

 taining two and a hall per cent of protochloride of xulphur ; after 

 remaining in the solution for two or three minutes, it must be taken 

 out and washed with water to remove excess of the chloride. By 

 these processes the caoutchouc takes up from ten to fifteen per cent, 

 of sulphur, one to two parts being chemically combined with it and 

 the remainder absorbed by its pores. The latter may be ni 

 by caustic alkaline solutions, bisulphide of carbon and other sulphur 

 solvent*. It is also gradually eliminated by the continued expansion 

 and contraction which this kind of caoutchouc undergoes in several of 

 it* mechanical applications. Another process of vulcanisation, i.j 

 which the excess of sulphur token up by the pores is avoided, consists 

 in heating the articles, manufactured of ordinary caoutchouc, for two 

 or three hours in a solution of protosulphide of potassium contained in 

 close vessels at a temperature of 284. After washing first in alkaline 

 solution and then in water, the objects are found to be very equally 

 and thoroughly sulphurised. 



Vulcanised caoutchouc is quite as elastic as the normal substance. 

 Its great advantages over the latter are that it retains its elasticity 

 when subjected to temperatures below the freezing point, an.i 

 above the boiling point of water : conditions under which unvulcanised 

 caoutchouc would become in the one case quite hard, in the other soft 

 and adhesive. 



CAOUTCHOUC MANUFACTURES. The name India-rMtr is 

 extensively applied to this substance, and might have been adopted in 

 the present case ; but already many of the manufacturers are shorten 

 ing it into the form of rubber; and, for aught we can tell, further 

 changes of designation may take place. We shall therefore adhere to 

 the original name. 



Few departments of manufactures have owed more to the ingenious 

 contrivances of one man than that of caoutchouc owes to Mr. Thomas 

 Hancock, who took out his first patent nearly thirty years ago, and 

 hag secured more than a dozen patents in all. His name must neces- 

 sarily be mentioned frequently in any fair account of the progress of 

 this branch of industry, even if he had not been the author of the best 

 extant work on the subject. It will be convenient referring to the 

 NATURAL HISTORY DIVISION for an account of the growth and early 

 history of this remarkable substance to commence with the year 

 1819, and rapidly glance at the chief inventions down to the present 

 time. 



1819. Caoutchouc receivedits name of India-rubber from it remark- 

 able property of rubbing out pencil-marks ; but its elasticity and its 

 imperviousness to moisture were known to the natives of the countrii - 

 where the tree grows ; and it was natural to expect that Euro|iean ami 

 American manufacturers would endeavour to apply the substance in 

 such away as to render these pro]>crties available. Mr. T. H 

 commenced his experiments with the substance in 1819. Hr I, It tlut 

 one of the important questions to be determined was, whether 

 chouc can be dissolved so as to render it useful in that state. He first 

 began with oil of turpentine, a liquid which is now known to be 

 suitable to the purpose; but his early attempts were unsuccessful. 



1820. Laying aside the solvent operation for. a time, Mr. Hancock 

 applied his ingenuity to various modes of cuttin u-honc 



(imported in bottle-shaped masses) into thin pieces, ami applyin: 

 as elastic additions to various articles of dress. He took 

 patent in 1820, for a method of applying these elastic pie< 

 wrists, waistcoat-backs, waist-belts, pockets, brao 

 gaiter-straps, stockings, garters, riding-belts, stays, boots, shoes, pat- 

 tens, and clogs. In the articles first manufacture I mi<lrr this ; 

 the elastic pieces were fastened to the garments by sewing; but tin 

 stitches broke away, and the holding was not secure. He th 

 made the pieces additionally thick at the edges, and steeped tl 

 hot water, to enable them to resist better the tearing action of the 

 stitches. One of his contrivances was to cut the bottles of caoutchouc 

 into rings, and apply these rings to the tops of gloves and stocking... 

 Another was a mode of joining surfaces by pressure of the caoutchouc 

 under hot water. A third was that of cutting the material into thin 

 slices by a sharp-edged cutter working under coM water. By degrees 

 there accumulated around him a large quantity of fragments of caout- 

 chouc, which he endeavoured to bring into some use; he in 

 a mattirator, consisting of a spiked roller working inside a -pik,.] 

 hollow cylinder; the tearing action of this machine, when the roller 

 was made to rotate, gradually mode the fragments hot, and combined 

 them all into one mass. This advance was a very important one ; th* 

 process was not patented, but Mr. Hancock contrived to keep tlx 

 secret to himself and his workmen during the long p.Ti.l of tv,.I\. 

 years : surreptitious imitators were thrown off the right scent by the 

 process being called " pickling." 



1821. The masticating process was exposed to this difficulty : tl:.' 

 gum resisted with immense force the tearing action, iusomncli tli.it 

 only two ounces at a time could be masticated by the wooden mm -liine 

 first made; but in 1821 an iron machine was made, worked by horse 

 power instead of by a winch, and with it 1511m. could be treated at 

 once. It was found, also, that if the caoutchouc were first heated to 

 about 800*, the mastication was more readily performed. 



1 822. Improved forms of machine, and improved modes of heating 

 the caoutchouc, enabled the manufacturer to work up a larger and 



