GUT′TA PERCHA

The concrete juice of the Is on andro Gutta , a tree growing only in the Malayan Archipelago, and of other species of the same genus. The stem of the gutta-perch a tree grows to the diameter of 5 or 6 feet, and on being notched yields a milky juice, which, after exposure to the air for some time, solidifies, forming the gutta perch a of commerce. It arrives in this country in irregular blocks of some pounds in weight, usually containing a large portion of impurities in the form of pieces of wood, stones, and earth. To prepare this crude product for manufacturing into useful articles, the blocks are first cut into slices, and then torn into shreds. These are softened by hot water, and kneaded in a ‘masticator,’ the stones, earth, and other impurities, being gradually washed away by water. After several hours the gutta perch a is found to be kneaded into a perfectly homogeneous ma , which is rolled or drawn into sheets, bands, or tubes, as required. Prop., . Gutta perch a is a tough, inelastic substance, becoming soft and plastic at 212° Fahr., at which temperature two pieces may be firmly welded together. It is one of the best insulators of electricity, is impervious to moisture, and resists the action of acids and alkalies to a great extent. Its best solvents are benzol, chloroform, bisulphuret of carbon, rectified mineral naphtha, and rectified oil of turpentine. All these di olve it readily. According to the analysis of Payen, the purified gutta perch a of commerce consists of 75 to 828 of chemically pure gutta perch a, which is insoluble in ether and alcohol, and a white and a yellow resin, soluble in boiling alcohol. Uses. These are numerous and varied. No substance, perhaps, with the exception of caoutchouc, has been ‘tortured’ to so many different purposes. Its perfect plasticity when warm, and its capability of receiving the most delicate impre ions, render it invaluable in many cases where india rubber would be usele . Beautiful mouldings, picture frames, and a number of ornamental articles, are made from it. To the chemist and photographer it is of great use as a material for making bottles, carboys, photographic baths, and voltaic battery cells. One of the most important uses to which it has been applied is for enclosing the metallic wires used for telegraphic purposes. Its indestructibility by water, its plasticity, and high insulating power, have rendered it particularly valuable for this purpose. At the International Exhibition of 1862 the Gutta Percha Company exhibited one mile of covered wire perfectly insulated, which was hardly thicker than common sewing cotton. Gutta perch a may be rolled into thin transparent sheets, which, being perfectly impervious to moisture, are well adapted for surgical purposes. Again, a solution of gutta perch a in chloroform forms an excellent dre ing for incised wounds, and a protection for abraded surfaces, burns, . It is used in the same way as collodion.