Caoutchouc, Elastic Re-sin, ox India ruller, is a substance produced from the Syringe Tree, or Iatropha elastica, L. which is a native of South America. It oozes in the form of vegetable milk, from incisions made in the tree, and is principally collected in wet weather, when it flows abundantly.

Various conjectures have been formed by the most eminent botanists, and chemists, as to the means used for inspissating and indurating this vegetable substance. The general opinion, however, is, that it concretes gradually when exposed to the air. It is particularly celebrated for the uncommon flexibility and elasticity, which it displays immediately on acquiring a solid consistence, and for the many purposes to which it is applied by the Indians, who make boots of it that are impenetrable to water, and when smoked, have the appearance of real leather. They also make bottles of it, to the necks of which reeds are affixed, and through these the liquor is squirted by pressure. The inhabitants of Quito, in Peru, also prepare from this substance a species of oil-cloth and canvas, which are formed by moulds made of clay, and worked into a variety of figures. Over these moulds is spread the juice obtained by incision; and, as often as one layer is dry, another is added, till the vessel acquires a proper thickness; when the whole is held over a strong smoke of burning vegetables, which gives it the texture and appearance of leather. Before the operation is completely finished, the substance, while still soft, will admit of any impression being made on its surface, which is indelible.

The chemical properties, and other interesting peculiarities of this elastic resin, have been diligently explored by the most ingenious natural philosophers of Europe, from the time it was first known. Various experiments have been made to dissolve it, and to ascertain whether it would assume different figures, with the same facility as it did in its original state This has been effected by the following simple process: Mr.WINCH put a pound of good vitriolic aether into a bottle, capable of containing four pounds, of any common fluid. On this aether he poured two pounds of pure water, stopped the bottle, inverted it, and agitated both liquids for several minutes, in order to mix, or, rather, to wash the aether in the water. On subsiding, as the aether floated on the top, he left the bottle in the inverted di-rection, opened it cautiously, substituted his thumb for the stopper, and thus let the water gradually escape into a vessel beneath. This operation he performed re-peatedly, till the sixteen ounces of aether were reduced to five. Having thus obtained a very pure aether, he found it to be the most perfect solvent of clastic gum. When immersed into it, after being cut into small pieces, it began to swell in a very short time; and, though the aether acted on it but slowly at first, yet, in five or six hours, the whole was completely dissolved, and the liquor remained transparent. If too large a proportion of elastic gum be employed, it will subside to the bottom; and may, after being taken out of the bottle, be moulded into any form, so as to retain its former elasticity.

The caoutchouc is at present chiefly employed by surgeons, for the injection of liquids, and also by painters, and others, for rubbing out pencil marks, etc. ; though we do not hesitate to say, that it may be advantageously used for socks, or even shoes and boots, as well as various useful articles of domestic convenience.

Caoutchouc - An elastic substance resembling that imported from South America, is now prepared from the Caoutchouc-fine, or Urceola elastica, a native of the Prince of Wales's Island, in the East Indies. On wounding the bark of this plant, a milky fluid exudes; which, on exposure to the air, separates into an elastic coagulum, and a watery liquid. - The former possesses all the properties of the common India rubber, and may now be procured from our Indian Colonies.