Page:The American Cyclopædia (1879) Volume III.djvu/746

736 CAOUTCHOUC hydrochloric acid. On being pressed between folds of cloth and dried, it becomes transparent. It swells by long-continued exposure to boiling water, but regains its form after being removed some time. Alcohol does not dissolve it, but precipitates it from its solution in ether. It is slightly soluble in ether free from alcohol, more soluble in coal naphtha, oil of turpentine, and chloroform ; but its best solvents are sulphide of carbon, and especially the liquid hydrocar- bon, called caoutchoucine, obtained by distilling the crude caoutchouc. The weak acids and alkaline solutions have no effect upon it. On evaporating its solution, the substance is re- covered in some instances elastic and dry as before, so as to serve the purposes of a varnish, which possesses the properties of the original juice ; or it is obtained in an adhesive, inelastic state. At the temperature of about 248 F. it melts and remains in a sticky condition, unless long exposed to the air in thin layers. It read- ily inflames and burns with much smoke. Its elasticity is very remarkable ; and when a piece of it is stretched, heat and electricity are evolved. If a piece is kept distended for two or three weeks, its elasticity is lost ; exposure to temperature as low as 40 produces the same effect ; but the application of a gentle heat im- mediately restores it. This property is taken advantage of in the manufacture of elastic textile fabrics, woven of the inelastic threads, which are afterward made elastic by heat. At 600 it is partially volatilized, and the vapor when condensed is the oily substance called caoutchoucine, which has been before mentioned as the best solvent of caoutchouc. According to experiments made many years ago at Utrecht, it yields at a red heat about 30,000 cubic feet of hydrocarbon gas to the ton, quite free, of course, from sulphur and ammonia compounds, and possessing illuminating properties much superior to those of the best oil gas ; but its expensiveness prevents its being used in this way. According to the analysis of Prof. Fara- day, the gum is a hydrocarbon consisting of 8 equivalents of carbon and 7 of hydrogen, which would require the proportion of 87'27 of carbon and 12'73 of hydrogen in 100 parts. The num- bers found by him were respectively 87'2 and 12'8. The juice, as obtained from the tree, gave in 100 parts Water containing a little free acid B6-8T Caoutchouc 81-70 Albumen 1-90 Wai trace. A nitrogenized body soluble in water 7'18 A substance insoluble in water 2-90 100.00 Caoutchouc was long known before its most valuable qualities were appreciated. La Con- damine was the first to give a particular description of the gum, which he did in a communication to the French academy of sciences in 1736. Again in 1751, after a res- idence of ten years in the valley of the Amazon, he brought the subject into notice, and called attention to the memoir of M. Fres- neau, who had found the tree in Cayenne. In 1761 MM. Herissent and Macquer reported their chemical observations on caoutchouc to the royal academy; and in 1768 M. Grossait published his experiments for obtaining good tubes of India rubber by means of ether and boiling water. Dr. Priestley refers to it, in the preface of his work on "Perspective " (1770), as a substance which had just been brought to his notice, as admirably suited for rubbing out pencil marks, and as being then sold at the rate of 3s. sterling for a cubical bit of about half an inch. In 1797 a patent was obtained in England by a Mr. Johnson for rendering cloth water-proof by covering one side with a varnish made of India rubber dissolved in equal parts of oil of turpentine and spirits of wine, and sifting over the surface silk, wool, flock, and other substances; and in 1813 a patent was issued in the United States to Jacob F. Hummel of Philadelphia for a varnish of gum elastic. In 1819 Mr. Mackintosh, who was engaged in the manufacture of cudbear, made an arrangement with the Glasgow gas works to receive their tar and ammoniacal products. It occurred to him that the oil of naphtha qb- tained from these might be useful as a solvent for India rubber, and in 1823 he obtained a patent for the manufacture of water-proof fabrics, since widely known as "mackintosh- es." He established a manufactory at Glas- gow, and subsequently, with others, went into the business on a large scale at Manchester. Mr. T. Hancock, who became associated with him, had already in 1820 obtained a patent " for an improvement in the application of a certain material to various articles of dress, and other articles, that the same may be ren- dered elastic." In 1825 Thomas C. Wales, a merchant of Boston, introduced the original Para overshoe in its rough state as made by the Indians of Brazil, and soon caused an im- provement in its shape by sending the native shoemakers American lasts. In 1828 nearly half a million India-rubber overshoes were ex- ported from Brazil to Europe and the United States. In 1832 Wait Webster of New York received a patent for attaching soles to gum elastic boots and shoes, and the next year similar patents were granted to Nathaniel Ruggles of Bridgeport, Conn., and to Samuel D. Breed of Philadelphia. In 1833 boots were exhibited at the fair of the American institute by J. M. Hood of New York, which had been made here and sent to South America to be varnished with the fresh juice of the caou- tchouc tree. In 1826 and 1827 Messrs. Eattier and Guibal, proprietors of a factory at Saint- Denis near Paris, employed machinery for cut- ting filaments of India rubber, of which they made fabrics. Subsequently machines for this purpose were patented in England by West- head of Manchester, Mr. Nickels, and others, which cut threads from a flattened disk of rub- ber varying in fineness from 700 to 5,000 yards