a well-known substance extracted from the pine. Under the article PINUS (Encycl.), we have given an account of one process by which this extract is made; but the following, which is taken from the 31st volume of the Journal de Physique, is very different, and probably better. The pine from which turpentine is extracted, is never fit for this operation till it be thirty years of age. The extraction is begun in February and continued to the end of October. Incisions are made with an hatchet, beginning at the foot of the tree on one side, and rising successively; they are repeated once or twice a week, the size about one finger's breadth across, and three or four inches long. During the four years in which it is continued, the incisions have risen to about eight or nine feet. Then the incisions are begun on the other side; and during this time the old ones fill up, and may be again opened after some years, so that a tree on a good soil, and well managed, may yield turpentine for a century. At the bottom of the tree, under the incision, a hole is dug in the ground to receive the resin which flows from the tree. This resin is called terpentine brat, is of a milky colour, and is that which flows during the three summer months; it requires further purification.
The winter crop is called barbas galipot, or white resin: it sticks to the bark of the tree, when the heat has not been strong enough to let it flow into the trough in the ground. It is scraped off with iron knives.
Two methods are practised for purifying these resins. That which is followed at Bayonne is to have a copper cauldron which will hold 300 lb. of materials fixed over a fire, and the flame circulating at the bottom of the copper. The turpentine is put in, melted with a gentle heat, and, when liquid, it is strained through a straw basket made for the purpose, and stretched over a barrel, which receives the strained turpentine. This purification gives it a golden colour, and may be performed at all times of the year.
The second manner, which is practised only in the mountain of De Buch, near Bordeaux, consists in having a large tub, seven or eight feet square, and pierced with small holes at the bottom; set upon another tub to catch the liquor. This is exposed to the hottest sun for the whole day, filled two-thirds with turpentine, which as it melts falls through the holes, and leaves the impurities behind. This pure turpentine is less golden-coloured, and is much more esteemed than the other. This process can only be done in the summer.
To make oil of turpentine, an alembic, with a worm like that used by the distillers, is employed here. It generally contains 250 lb. of turpentine, which is boiled gently, and kept at the boiling point till no more oil passes, when the fire is damped. This generally gives 60 lb. of oil, and the operation lasts one day.
The boiling turpentine, when it will give no more oil, is tapped off from the still and flows into a tub, and from thence into a mold of sand, which it fills, and is suffered to cool for at least two days without disturbing it. This residue is known under the name of oleophony. It is of a brown colour, and very dry. It may be made clearer and nearer in colour to that of the resin, by adding hot water to it before it is tapped off the still, and full boiling and stirring the water well with it, which is done with a bed of wet straw; and it is then sold for resin, but is little esteemed, as it contains no essential oil.