The new balsam, distilled with the addition of a small quantity of an oxidizing agent, as chlorine, hypo-chlorite of lime, or bichromate of potash, yields an essential oil of a fine blue, whilst ordi nary copaiba, containing soft resin, affords hardly any coloured essential oil ; and cold sulphuric acid produces with copaiba a purple coloration similar to that obtained with cod-liver oil.
1Vood-oil from Moulmein, when filtered, is a transparent liquid, of a somewhat dark-brown when seen by transmitted light, but appearing opaque and of an obscure green if viewed by reflected light. It possesses, therefore, in a very marked degree, the dichroism observable in all resin oils obtained by the action of fire. This character determines the nature of wood-oil, and shows that it is not simply a natural product like copaiba, but that it is in part the result of a liquid modification of the Dipterocarpus resin, effected by the agency of heat. Moulmein wood oil is of somewhat greater consistence than olive oil ; it has a sp. gr. of -964, and possesses an odour and taste very analogous to those of copaiba. It dissolves in twice its weight of absolute alcohol, with the exception of a minute residue which is deposited upon repose.
The most curious property of the Dipterocarpus wood-oil is that of solidifying when beated in a closed vial to 266° F. ; at this temperature the oil becomes turbid, and so gelatinous that it is not displaced upon the inversion of the phial. After cooling, the solidification is yet rnore perfect ; but a gentle warmth, assisted by slight agitation, restores its former liquidity. The resin of Vateria Indica is insoluble in alcohol, and very inaperfectly so in ether ; whilst the green resin of wood-oil is easily soluble in either of these menstrua.
Camphor wood-oil, from the Dryobalanops cam phora, belongs to the class of volatile oils. It is iised largely in Singapore as a substitute for tur pentine, and sells at from 15 to 20 cents a bottle.
IVood-oil of China, the rung-tsze-yu of com merce, is obtainedfrom the seeds of the Elaeococcus verrucosa, which grows plentifully in the valley of Yang-tse. In China, the cold-drawn wood oil, Peh-t'ung-yu, is pale, and is used for lamps and for varnishing furniture and the better class of umbrellas.. A darker thick oil, called Siu-yu, is obtained by heat and preskire from the seeds and fruits of the Elmococcus and Jatropha, It is used in making putty, and in caulki4 and painting ships and boats. There is a reddish'kind called Hung t'ung-yu. The best wood-oil of China comes to Hankow from Shin - chan - fu, one of the sub stances of which the well-known and much-prized China lacquer is made.
Deodar or shemanatahu oil, froni\ the Ery throxylon areolatum, and Sissoo woodil, from Dalbergia sissoo, are empyreumatic medicinal products.
Teak wood-oil is a dull ash-coloured oil, pro curable in most of the large bazars of India ; ' when allowed to rest for some time, it separates into two layers, the upper one a dark-coloured clear stratum, and the lower a more solid de posit. Its chief use is for applying to wood work of all sorts, either alone as a natural varnish, or in combination with certain resins.
Wood-oil from the species of Dipterocarpus is used for painting the beams and wood-work of native houses, and may also be mixed with paint when not exposed to the sun. It is an excellent solvent of caoutchouc ; it has 'ibeen used as a substitute for fish-oil in curing leather, and found to answer. It makes an excellent house varnish, and the Burmese employ it ex tensively in the manufacture of torches. It is a good substitute for copaiba balsam in the treatment of gonorrhcea, given diffused through almond mixture or gum water. Dose, 10 to 15 minims, repeated thrice daily, or as often as necessary. A compound tincture of gurjun is an efficient substitute for Frank's well-known specific for the treatment of gonorrhcea. Dose, 20 to 30 minims, in a little milk or sugared water.
Wood-oil is decomposed by nitric acid into a black spongy substance, hard and brittle, heavier than the liquid part of the oil into which it sinks ; the liquid part assumes a colour nearly like that of port wine, and is about as fluid as water, much more liquid than the natural wood - oil. A thin coating of that liquid part applied to a board of deal wood formed in 24 hours a transparent varnish perfectly even and bright. The spongy matter above alluded to seems to possess the seine , properties as a mixture of resin and annotto. Two identical substances are obtained by dissolving with nitric acid the common asphalte used for pavements. A small quantity of sulphuric acid poured incautiously on the second day into the wood-oil which had been in contact with nitric acid, caused it to rush out of the glass with a violent effervescence and disengagement of smoke, aromatic fumes, and a heat of about 200° Fahr. ; the aromatic smell was very sweet, and much like benjamin.—Smith ; Roxb. ; Journal de Pharmacie, 1856 ; Pharmaceutical Journal, xiv. xv. O'Sh. ; Rohde, MSS.