Oil of Aleurites triloba.
Oil of Aleurites Triloba.—The Aleurites triloba Forst. is a small tree belonging to the Euphorbiaceae. It is widely diffused throughout the tropics. The fruit is a nut nearly as large as a walnut, consisting of a thick shell enclosing a kernel containing much protein and rich in oil, of which it is said to yield nearly one-half its weight by expression. The nuts strung together on the fibers of the palm leaf were formerly used in many Pacific islands as a substitute for candles. The oil has been long known in the various countries inhabited by the plant, being called in Jamaica Spanish walnut oil, in India Belgaum walnut oil, in Ceylon kekune oil, and in the Hawaiian Islands kukui oil. It is very fluid, of an amber color, without odor, of a nutty, pleasant taste, congealing at 0° C. (32° F.), insoluble in alcohol, readily saponifiable, "and very strongly drying." It is said to be a mild cathartic, acting like castor oil, but more promptly and without griping effects. (J. P. C., 3e ser., xxiv, 228.) The dose is from one-half to one fluidounce (15-30 mils), the smaller quantity generally answering. The cake left after the expression of the oil, given to a dog in the dose of about half an ounce (15 Gm.), produced no vomiting, but acted strongly as a purgative.
The oil of the Tung Tree, Aleurites cordata (Thunb.) Mull.-Arg., is used to a large extent in the arts in China, under the name of Chinese wood oil or tung oil. (This must not be confounded with the Indian oil of wood.) It is prepared in China by a crude process of expression. It occurs in two forms, white oil, a moderately thick, yellowish, transparent liquid, and the black oil, which is thick, black, and opaque. Wood oil is used in China and Japan either as a direct application to wood or mixed with various substances, as lacquer varnish, or paint. Its most remarkable characteristic is its extraordinary drying property, which is said to exceed that of any known oil. When applied to wood it forms a resinous layer which is affirmed to be impermeable by water and ordinary solvents. Wood oil is also exported to Europe, where it is used in the making of varnishes. This oil is obtained from the seeds of the tung tree, which contains about 53 per cent. of fixed oil. According to R. H. Davies, its sp. gr. at 15.5° C. (60° F.) is 0.94015; it remains liquid at -13.3° C. (8° F.). 100 Gm. of the oil require 0.39 Gm. potassium hydroxide for neutralization, and 21.1 Gm. for complete saponification. (P. J., 1885, 636.) E. M. Holmes believes that the dark colored oil is made by boiling the kernels previous to expression, the cold drawn oil being colorless, inodorous, and nearly tasteless. The latter, according to Cloez (C. R. A. S., 1875, vol. lxxxi, 469), has the sp. gr. 0.9362, congeals at -18° C. (-0.4° F.) to a transparent mass, solidifies rapidly when exposed to light in a closed vessel, and is the most drying oil known. (C. D., May, 1902.) (See also Proc. A. Ph. A. 1897, 677; and Chem. News, 1912, 14.) Over 60,000 kilo-grammes are said to be sent yearly from Hankow, on the Yang-tse-kiang, to the various Chinese seaports. It has been used in ulcerations and skin diseases. The seeds of the tung tree are used in China for killing rats, and are also affirmed to have emetic properties.