TURPENTINE. See RESINS.
Turpentine, of which there are various kinds, are all products of some of the species of the pinus. From this genus are obtained not only turpentine, but resin, pitch, tar, &c. which are employed so ex tensively in ship-building, and in the rig ging also : likewise in varnishes.
There are three varieties of pine tur pentine, commonly known under that name in Europe : namely, 1. The com mon turpentine, obtained chiefly from the pinus sylvestris (Scotch fir). 2. The Strasburgh turpentine, yielded by the pi nus picca (silver fir). And, 3. The Ve nice turpentine, procured from the pinus larix (larch). Of the three first mention ed turpentines, the Venice is the thinnest and most aromatic ; the Strasburgh the next in these qualities; and the common is the firmest and coarsest. The two form er are often adulterated by a mixture of the common turpentine and oil of turpen tine; and it is to be observed; that the terms Venice and Strasburgh turpentine are not now appropriate, as they are pro cured from various countries.
Common turpentine is obtained largely in the pine forests in the south of France, in Switzerland, in the countries on the north of the Pyrenees, in Germany, and in many of the southern States of North America. The greater part of what is consumed in this country is imported from North America. The method of obtaining it is by making a series of in cisions through the bark of the tree, from which the turpentine exudes, and falls down into holes, or other receptacles at the foot.
The process is described very ace-n rately by Duliamel and others, as practis ed in the south of France. The fir is generally allowed to remain untouched till it is thirty or forty years old. When it is to be worked, which is early in the spring, a small hole is first made in the ground at the foot of the tree, the earth. of which is well rammed, and serves as a receptacle for the juice. The coarse bark is then stripped off from the tree, a little above the hole, down to the smooth inner bark, after which a portion of the inner bark, together with a little of the wood, is cut out with a very sharp tool, so that there may be a wound in the tree about three inches square, and an inch deep. Immediately afterwards the tur pentine begins to exude in very transpa rent drops, which escape chiefly from the wood immediately under the inner bark. The hotter the weather is, the greater is the supply of resin ; and to facilitate the supply, the incisions are enlarged every three or four days, by cutting off thin slices, till at the end of the year it is about a toot and a half wide, and two or three inches deep. The whole time during which the turpentine flows is from the end of February to October. In the win ter it entirely ceases, but in the ensuing spring a fresh incision is begun a little above the former, and managed in the same manner. This practice is continued
annually for about twelve or fifteen years in some parts, and in others a shorter time, on the same side of the tree, till the later incisions are so high as to be out of reach without the assistance of steps ; af ter which the contrary side of the tree is begun upon, and worked in a similar manner fir as many years, during which time the first incisions are grown up, and are fit to be cut afresh. In this way, a healthy tree, in a favourable soil, may be made to yield from six to twelve, or more, pounds of turpentine annually, sometimes for a century ; and even the timber is not soon injured by this constant drain. The flow of turpentine discontinues altogether about October, and the liquid resin col lected during the year, from each tree, is put together for further purification. But a considerable quantity of the resin has concreted during that time around the in cision, particularly as the heat declines ; and in the winter, when it has hardened considerably, it is scraped off, and forms what is technically called barras, or in some provinces galipot, which differs from the more liquid turpentine in consist ence, and probably contains a less pro portion of essential oil. The galipot is much used in making flambeaux when mixed with suet; but the greater part of it, as well the liquid turpentine, is 'Subject ed to th•ther processes. The Strasburgh turpentine, the produce of the silver fir, is the most fragrant of all the pine turpentines, and only inferior to the true Chio ; kit it is not often seen in the shops. It is obtained by rude incision of the bark by the peasants in the vast pine forests on the western Alps. The first cut made as high as the hatchet will reach, and these are renewed annually from above downwards to within a foot of the ground. But the finest kind of tur pentine yielded by this tree, is that which exudes from soft tubercles, or swellings of the inner bark. The peasants carry with them a large cow's horn, with the point of which they pierce these tuber cles, and collect the juice in its hollow.
'Ile true Venice turpentine, or resin of the larch, is obtained from the Tyrol and Savoy, and also from Dauphiny, by boring holes about an inch in diameter, with a gentle descent, in the most knotty parts of the tree. To these are adapted long perforated pegs, which serve as gutters to convey the juice into troughs placed be neath. It is yielded during the whole of the summer, and is simply purified by straining through hair sieves. A full grown larch will sometimes yield seven or eight pounds of turpentine annually for forty or fifty years.