Oleum Terebinthinae gallicum. - Franzosisches Terpentinol. - Essence de Terebenthine Francaise.
Origin. The pine growing on the dunes ("Landes") of Southwestern France and used for the production of turpentine is Pinus Pinaster, Sol. (Pinus maritima, Poir.), the Pin maritime or Pin de Bordeaux of the French (Ger. Seestrandkiefer or Igelfohre). The country thus utilized constitutes a triangle outlined by the Atlantic ocean, the Garonne and Adour rivers. The pine forests cover an area of 200000 ha. in the Departement de la Gironde, 500000 ha. in Lot-et-Garonne2). The principal markets for turpentine, turpentine oil, galipot and colophony are Mont de Marsan, Dax, Bordeaux and Bayonne.
The former production of turpentine in the Sologne ceased after the frosts of 1879/80 had largely killed the forests. However, the industry has recently been revived8).
The Production of Turpentine4). The production of turpentine begins in spring with the flow of the sap. The bark near the base of the tree is removed and a wound made (carre)4 4 cm. long, 9 cm. wide and 1 cm. deep, i. e. to the sap wood. Beneath this wound a curved incision is made with a special instrument, and a strip of tin (crampon) inserted. Underneath it an earthern vessel is fastened by means of a nail so that the oleoresin will flow into it. In lengthening periods, varying according to the season, the wound is elongated upwards (piquage), the workman making incisions 1 to 2 cm. deep with his axe (hachot).
1) Herty and Stem, Zeitschr. f. angew. Chem. 21 (1908), 1374.
2) Vezes, La gemme Landaise et son traitement. Bordeaux 1905. - La r6colte et le traitement de la gemme du pin maritime. Bordeaux 1910.
3) Corps gras industriels 34 (1908), 178.
4) Vezes, loc. cit. - Oesterle, Die Harzindustrie im Sudwesten Frank-reichs. Berichte d. deutsch. pharm. Ges. 11 (1901), 217.
Fig. 9. French Method for the Production of Turpentine. According to the Reports of Roure-Bertrand Fils.
Fig. 10. Modern French Turpentine Distillery. According to the Reports of Roure-Bertrand Fils.
The oleoresin (gemme) flows slowly into the pot. A part of it, however, dries as it flows down and covers the ground with a yellowish white crust (barras or galipot). This is also collected and brought into commerce as such. The contents of the pots are emptied into larger collecting vessels (escouarte) or ditches (barcous) every 14 to 20 days. The galipot is collected twice during the campaign, viz., in June and November.
During the second and subsequent years the wound is lengthened upwards to the extent of 75 cm. each year so that at the end of the fifth year the carre is almost 5 m long. Each year the pot is fastened at a higher point. When too high to be reached from the ground, a peculiarly constructed ladder (fig. 9 p. 70) is used.
The second carre is started to the right of the first and the third between the second and first so that they are separated by 1/3 of the circumference of the tree. Not infrequently three other wounds are later inflicted between the first three.
A distinction is made between the gemmage a vie, which implies a protection of the tree, and the gemmage a mort which does not consider the life of the tree. The tapping of the trees begins with their 15th year and occasionally lasts 45 years so that trees may acquire the age of 60 years.
Distillation of the turpentine. The distilleries in the Landes are very numerous, there being one on almost every property. However, for the sake of avoiding fires, they are not in the forests. As a rule they are very primitive. There are probably 2 or 3 modern distilleries with modern equipment (fig. 10, p. 71) which belong to the large wood dealers1). The common method is that of distillation over the free flame with the introduction of water. The bottom of the still is either flat or concave, the sides are 15 to 20 cm. high. On the sides there rests a conical section, the lower diameter of which is 1 m., the upper 75 cm., topped by a disc on which rests the helmet. The bottom is provided with an exit tube 10 cm. wide through which the colophony is drawn off at the end of the distillation. At about half the height, the still is provided with an inlet tube through which the turpentine, liquified by heat, is allowed to enter the still. The capacity of the still is about 300 I. At the highest point of the helmet, a funnel with stopcock is applied through which the, water necessary for the distillation is allowed to enter. The distillation lasts somewhat more than an hour, hence from 8 to 10 distillations can be conducted in a day. The yield amounts to about 20 p. c. turpentine oil and 70 p. c. colophony, the loss of 10 p. c. being due to impurities and water contained in the turpentine.
1) R. Lienhart, Bull. Sciences Pharmacol. 17 (1911), 161.
The condenser consists of a copper spiral contained in a barrel through which water flows.
If the turpentine is not purified before distillation (distillation a cru) the yield is somewhat higher, but the residual colophony is not only impure but also dark in color so that it can be used only for the production of rosin oil. This oil is produced by distilling the rosin, to which some lime has been added, over direct flame. If a light colored, transparent colophony is desired, the turpentine is purified, previous to the distillation, by melting, decanting and filtration. (Distillation a terebenthine.)
The primitive method of distillation over direct flame has in many instances been replaced by the use of steam, either under pressure or superheated. The modified stills constructed for this purpose are protected by a series of patents1). Noteworthy is a recent patent by Castets (French patent No. 391835 of 1908). It admits of the continuous distillation of turpentine to turpentine oil and colophony under vacuum.
Properties2). d15.0,865 to 0,875; aD - 29 to - 23°. During storage, especially when carelessly stored, the angle of rotation diminishes1). This explains some of the deviations recorded from the above figures.
1) Vezes, La gemme Landaise, etc., p. 97. 2) Comp. also p. 11, footnote I.
When distilled, only a few drops pass over between 152 and 155°, about 85 to 90 p.c. boiling between 155 and 165° 2).