Gum Kauri. Agathis australis.
Gum Kauri.—This is an amber-like substance, varying from a soft cream-white to an amber color, dug in large quantities from the soil of Australia and New Zealand. It is a resinous exudation from the Kauri Spruce, Agathis australis Salisb. (Dammara australis Lamb.), of the Fam. Coniferae, but, as it first exudes and is found on the surface of the ground, it is not esteemed. According to Tschirch and Niederstadt, it contains kaurinic acid, C10H16O2, 1.5 per cent.; a- and ß-kaurolic acids, C12H20O2, 48 to 50 per cent.; kaurinolic acid, C17H34O2, and kauronolic acid, C12H24O2, together, 20 to 22 per cent. All these resin acids are soluble in solution of sodium hydroxide. Baume Caledonien consists of a solution of kauri gum in an equal weight of 90 per cent. alcohol. It has been used with alleged great success in the treatment of wounds and ulcers, of eczema and other skin affections, and as a substitute for collodion and the soluble sodium silicate. When applied to a well cleansed and dried wound it leaves a slight deposit of resin as a varnish, which is not affected by friction or contact with water.
The commercial product known as Manila copal, according to Tschirch and Koch, is derived from Agathis Dammara Rich. (Dammara orientalis Lamb.), a conifer. It consists chiefly of free amorphous resin acids, namely, alpha- and beta-mancophalolic acid, C10H18O2 (about eighty per cent.), and contains besides about 12 per cent. of a resin, C20H32O2, and about five per cent. of essential oil. The latter, when fresh, forms a liquid as clear as water, very mobile, having a pleasant odor, and the sp. gr. 0.840; it boils at from 165° to 170° C. (329°-338° F.), and mixes in all proportions with alcohol, ether, chloroform and fatty oils. See also the article on Copal.