CAOUTCHOUC

This curious substance is the inspi ated juice or sap of several plaots: the principal supplies are from South America, and are derived from the Siphon i a elastic a (Hevea caoutchouc), and probably from other Euphorbiaceous plants. It is often termed gum elastic and Indtan rubber. Its general properties and uses are well known. Among its more recent applications are those of elastic wove fabrics, formed of caoutchouc stretclied into threads and covered with cotton; and various water-proof clothing, which is made by interposing a laver of caoutchouc between two folds of the cloth, and then forcibly uniting them by pre ure. For this purpose the caoutchouc is di olved by coal naphtha, and in that state brushed over the surfaces which are to be united. Caoutchouc is a compound of carbon and hydrogen; when heated it fuses, and afterwards remains viscid; when subjected to destructive distillation at a high temperature, it yields four fifths of its weight of a highly inflammable and very light volatile oily liquid (hydrocarbon), which has been called caoutchoucine, and which is a good solvent of the unaltered caoutchouc. Washed sulphuric ether di olves caoutchouc, and it is also soluble in several e ential oils; but of these latter solutions the greater number leave it in a sticky state on evaporation. [s. 205]