History—The terebinth was well known to the ancients; it is the τέρμινθος of Theophrastus, τερέβινθος of other authors, and the Alah of the Old Testament.[674] Among its products, the kernels were regarded by Dioscorides as unwholesome, though agreeable in taste. By pressing them, the original Oil of Turpentine, τερεβίνθινον ἔλαιον, a mixture of essential and fat oil was obtained, as it is in the East to the present day. The resinous juice of the stem and branches, the true, primitive turpentine, ῤητίνη τερμινθίνη, was celebrated as the finest of all analogous products, and preferred both to mastich and the pinic resins. To the latter however the name of turpentine was finally applied.[675]
Collection—The resinous juice is secreted in the bark, according to Unger,[676] and Marchand,[677] in special cells precisely as mastich in P. Lentiscus. That found in commerce is collected in the island of Scio. To some extent it exudes spontaneously, yet in greater abundance after incisions made in the stems and branches. This is done in spring, and the resin continues to flow during the whole summer; but the quantity is so small that not more that 10 or 11 ounces are obtained from a large tree in the course of a year. The turpentine, hardened by the coolness of the night, is scraped from the stem down which it has flowed, or from flat stones placed at the foot of the tree to receive it. As it is, when thus collected, always mixed with foreign substances, it is purified to some extent by straining through small baskets, after having been liquefied by exposure to the sun.
When Tournefort[678] visited Scio in 1701, the island was said to produce scarcely 300 okes or ocche (one occa = 2·82 lb. avdp.); a century later Olivier[679] stated, that the turpentine was becoming very scarce, 200 ocche only, or even less, being the annual yield. It was then carefully collected by means of little earthen vessels tied to the incised stems. The trade is asserted to be now almost exclusively in the hands of the Jews, who dispose of the drug in the interior part of the Turkish Empire.[680]
Description—A specimen collected by Maltass near Smyrna in 1858 was, after ten years, of a light yellowish colour, scarcely fluid though perfectly transparent, nearly of the odour of melted colophony or mastich, and without much taste. We found it readily soluble in spirit of wine, amylic alcohol, glacial acetic acid, benzol, or acetone, the solution in each case being very slightly fluorescent. The alcoholic solution reddens litmus, and is neither bitter nor acrid. Two parts of this genuine turpentine dissolved in one of acetone deviate a ray of polarized light 7° to the right[681] in a column 50 mm. long.
Chian turpentine as found in commerce and believed to be genuine, is a soft solid, becoming brittle, by exposure to the air; viewed in mass it appears opaque and of a dull brown hue. If pressed while warm between two slips of glass, it is seen to be transparent, of a yellowish-brown, and much contaminated by various impurities in a state of fine division. It has an agreeable, mild terebinthinous odour and very little taste. The whitish powder with which old Chian turpentine becomes covered, shows no trace of crystalline structure when examined under the microscope.
Chemical Composition—Chian turpentine consists of resin and essential oil. The former is probably identical with the Alpha-resin of mastich. The Beta-resin or Masticin appears to be absent, for we find that Chian turpentine deprived of its essential oil by a gentle heat, dissolves entirely (impurities excepted) in alcohol sp. gr. 0·815, which is by no means the case with mastich.
The essential oil which we obtained by distilling with water 64 ounces of Chian turpentine of authentic origin, amounted to nearly 14½ per cent. It has the odour of the drug; sp. gr. 0·869; boiling point 161° C.; it deviates the ray of polarized light 12·1° to the right. In common with turpentine oils of the Coniferæ, it contains a small amount of an oxygenated oil, and is therefore vividly attacked by sodium. When this reaction is over and the oil is again distilled, it boils at 157° C. and has a sp. gr. of 0·862. It has now a more agreeable odour, resembling a mixture of cajuput, mace, and camphor, and nearly the same rotatory power (11·5° to the right). By saturation with dry hydrochloric acid, it yields a solid compound after some weeks. After treatment with sodium and rectification, the oil was found[682] to consist of C 88·75, H 11·40 per cent., which is the composition of oil of turpentine.
Uses—Chian Turpentine appears to have exactly the properties of the pinic turpentines; in British medicine it is almost obsolete. In Greece it is sometimes added to wine or used to flavour cordials, in the same manner as turpentine of the pine, or mastich.
GALLÆ CHINENSES SEU JAPONICÆ.
Botanical Origin—The plant which bears this important kind of gall, is Rhus semialata Murray (Rh. Bucki-amela Roxb.), a tree attaining 30 to 40 feet, common in Northern India, China and Japan, ascending in the outer Himalaya and the Kasia hills to elevations of 2,500 to 6,000 feet.[683]