Oil of Wood. Wood Oil. Gurjun Balsam.—In the P. J. for August, 1854 (p. 65), appeared an account by Charles Lowe of Manchester, of a "new variety of balsam of copaiba," derived from the East Indies. In a subsequent communication to the same journal (1856, 321) from Daniel Hanbury, it appears that this product, though offered for sale in the London market as balsam of copaiba, is known in India under the names of wood oil and gurjun balsam. Considerable quantities had been imported from Moulmein, in Burma, specimens of a similar drug had been received from Canara and Tenasserim, and it appears to be widely diffused in the Indian markets. This must not be confounded with the Chinese wood oil, which is used as a varnish. (See Oil of Aleurites.)
This liquid is obtained from Dipterocarpus turbinatus Gaertn. f., and several other species of Dipterocarpus growing in East India (Fam. Dipterocarpaceae), a very large tree which forms forests in Pegu and other parts of Farther India. A large notch is cut in the trunk of the tree, between two and three feet from the ground, and a fire made so as to char the wound. The juice then begins to flow, and is received in suitable vessels. Every three or four weeks the charred surface is cut off and burned anew. A single tree sometimes yields forty gallons in a season. D. tuberculatus Roxb. yields a liquid known in Burma as in oil, which is sometimes sold as gurjun balsam. (Proc. A. Ph. A., 1913, 223.) It is at first turbid, but may be clarified either by filtration or deposition. After filtration, wood oil is a clear, dark brown liquid, of the sp. gr. 0.964 (Hanbury), and, in consistence, odor, and taste, bears a close resemblance to copaiba. It is soluble in two parts of alcohol of the sp. gr. 0796, with the exception of a very small proportion of darkish flocculent matter, which subsides on standing. According to Lowe, it contains 65 per cent. of volatile oil, 34 of resin, and 1 of acetic acid and water. A characteristic property noticed by Lowe, by which it may be distinguished from copaiba, is that, when heated in a closed vial to 266° F. (230° F., Lowe), it becomes slightly turbid and coagulates, so that the vial may be inverted without changing the position of its contents, and this consistence is retained when the liquid cools. By a gentle heat with agitation the fluidity returns; but the liquid again coagulates if heated to 266° F. According to D. Brandis, this property of coagulation is characteristic of the wood oil from D. alatus Roxb. (P. J., xxv), a wood oil which is further to be opalescence of its distinguished by the greenish surface.
Guibourt states that wood oil does not solidify, like copaiba, with one-sixteenth of magnesia, and the two separate on standing. (J. P. C., xxx, 192.) De Vrij of Rotterdam, proposes the reaction of benzene with wood oil and copaiba respectively as a test to distinguish them. With an equal volume of the wood oil, benzene forms a turbid mixture, from which, after a long time, a resinous matter is deposited in flocculi; with copaiba it forms a transparent solution. (P. J., 1857, 374.) The volatile oil from gurjun balsam is a yellow, somewhat thick liquid, of sp. gr. 0.915 to 0.930, and has at times a high optical rotation— viz., -35° to -130°. The oil boils in larger part at 255° to 256° C. (491°-492.8° F.) and consists of a sesquiterpene; C15H24. With hydrochloric acid it yields a deep blue color. The resin left after distilling off the volatile oil is essentially gurjunic acid, C22H34O4. This when purified dissolves readily in ether and strong alcohol, and slowly in benzene. It melts at 220° C. (428° F.) and congeals again at 180° C. (356° F.). Fluckiger has also described a neutral resin from gurjun balsam, which is insoluble in caustic potash, fuses at 126° C. (258.8° F.), and is of the composition C28H46O2. Fluckiger (A. Pharm., 1876, 420) noticed that wood oil may be recognized by the violet color it assumes if dissolved in twenty parts of carbon disulphide and mixed with a drop of a cold mixture of equal parts of concentrated sulphuric and nitric acids.
According to O'Shaughnessy, the oil of dipterocarpus is little inferior to copaiba in the diseases for which that medicine is employed. T. B. Henderson has found it very useful in gonorrhea, given in the dose of a teaspoonful two or three times a day, uncombined. (M. T. G., 1865, 571.) It probably has a remedial influence on diseased mucous membranes similar to the different turpentines, which it appears to resemble in composition. The juice may be given in emulsion, in doses of from fifteen to forty minims (0.9-2.5 mils); the volatile oil from ten to thirty minims (0.6-1.8 mils).
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.