Gutta percha.

Nat. Ord. — Sapotaceae. Sex. Syst. — Decandria Monogynia.
Concrete Juice of Isonandra Gutta.
Description. — This is the product or milky juice of a large tree growing in Singapore and its vicinity, the Isonandra Gutta. The tree is very large, having a trunk from three to six feet in diameter, with numerous ascending branches, the extremities of which are crowded with petiolate, oblong leaves, green above, brownish beneath, and four or five inches long by two in width. The flowers are small and white.
History. This substance was introduced in 1842, to the profession, by Dr. William Montgomerie, a surgeon in the British army in the Indies. The mode pursued by the natives in collecting it, is to cut down the tree, strip off the bark, and then collect the milky juice in suitable vessels, which coagulates on exposure to the air. This he considers a wasteful course, as each tree yields only twenty or thirty pounds of the concrete juice, and probably a larger yield might be had by tapping the trees, and thus preserving them for future use. As received in this country it is rendered impure by the admixture of various foreign matters, from which it may be freed by kneading in hot water, or by melting it with oil of turpentine, straining, and evaporating the oil. Gutta percha is of a dull white, or whitish color, of a feeble odor, tasteless, at ordinary temperatures hard, almost horny, somewhat flexible in thin pieces, having an unctuous feel under the fingers, and very tenacious. It is softened by hot water or dry heat, and on cooling resumes its former state, and retains any form which may have been given to it. At 150° or 160°, it is soft, very plastic, and capable of being welded and molded into any form. When soft, it may be cut with a knife. Its specific gravity is 0.9791. It is insoluble in water, alcohol, alkaline solutions, and the weak acids. Ether and the volatile oils soften it in the cold, and imperfectly dissolve it with the aid of heat. Oil of turpentine dissolves it perfectly, forming a clear, colorless solution, which yields it unchanged by evaporation. Bisulphuret of carbon also dissolves it without change. It resembles caoutchouc and is a non-conductor of electricity. It is used for a number of useful and ornamental purposes. In the dissolved state it is used as a varnish impervious to moisture. Chloroform and benzole dissolve it. Pure gutta percha is analogous, in its ultimate composition, with caoutchouc ; the ordinary article of commerce contains pure gutta percha, a small quantity of a vegetable acid, casein, a resin soluble in ether or oil of turpentine, and a resin soluble in alcohol. It may be vulcanized in the same manner as caoutchouc, and undergoes a similar change of properties.
Properties and Uses. — Used in surgery, as bands and splints, to preserve limbs and joints in fixed positions, also for the formation of bougies, injection pipes, catheters, pessaries, artificial teats, forceps-handles, etc. The solution in bisulphuret of carbon is recommended as an application to the skin in incised wounds — the liquid speedily evaporates, while the gutta hardens, and holds the edges of the wound firmly together. The following compound is recommended for the hemorrhage supervening the extraction of teeth. Take of gutta percha an ounce ; best tar an ounce and a half; creosote a drachm ; shell lac an ounce. Boil these in a crucible, stirring or beating them well, until they are blended into a stiff, homogeneous mass. The compound is readily softened between the fingers, and is easily introduced into the bleeding socket. It must be pressed in, and the hemorrhage will be speedily checked. Mr. Acton states that the following preparation is useful for protecting exposed surfaces from contagions, poisonous contact, etc.; dissolve with a gentle heat one drachm of gutta percha in an ounce of benzole ; also half a scruple of caoutchouc in an ounce of benzole, and mix the two solutions. Apply it with a brush, the liquid evaporates leaving a delicate covering behind. An improved cement for uniting the parts of boots and shoes, and in the manufacture of articles of dress in which cement is required, is made of 64 parts by weight of gutta percha, 16 parts of caoutchouc, 8 parts of pitch, 4 parts of shell-lac, and 8 parts of oil ; the ingredients are melted together, the caoutchouc having been previously dissolved. A cement for uniting sheet gutta percha to silk or other fabrics, is composed of gutta percha 40 lbs., caoutchouc 3 lbs., shell-lac 3lbs., Canada Balsam 14 lbs., Liquid styrax 35 lbs., gum mastic 4 lbs., and oxide of lead 1 lb. Another for uniting it to leather, as soles of shoes, etc., consists of: — Gutta percha 50 lbs., Venice turpentine 40 lbs., shell-lac 4 lbs., caoutchouc 1 lb., and liquid styrax 5 lbs.