Origin and Production. Venice turpentine is obtained from the larch, Larix decidua, Mill. (Larix europaea, DC, Pinus Larix, L), which grows in the mountainous sections of central Europe. It is collected principally in the Southern Tirol, in the vicinity of Meran, Mals, Bozen, Kastelruth and Triest, also in Steiermark. Although schizogenous ducts occur in small numbers in all parts of the wood and bark, experience as well as the botanical investigation by H. von Mohl in 18591) have taught that they are more numerous and larger in the heart wood. Hence the production of larch turpentine has to be conducted differently from that of the other turpentines. The trees are not tapped in the region of the sap wood, but in spring one or several holes are bored to the center of the tree with bits 2,5 to 4 cm. in diameter. The openings are closed with wooden stoppers and are not opened until fall when the accumulated balsam is removed with an iron spoon. The opening is again closed for the accumulation of more balsam during the following summer.
1) An exact communication as to the mode of collecting may be found in a paper by A. Tschirch and G. Weigel in the Arch, der Pharm. 238 (1900), 412.
2) Tschirch and Weigel, Ioc. cit, p. 413.
3) Fluckiger, Jahresber. f. Pharm. 1869, 38; also Pharmacographia p. 615.
4) Arch, der Pharm. 250 (1912), 104.
If one or two holes are bored in the tree, the yield of balsam during the summer months amounts to but several hundred grams; this, however, remains constant for many years. If a larger number of holes are bored into a single trunk, and the balsam is induced to flow freely, several pounds of balsam may be obtained in a single summer. In this case, however, the tree is exhausted after a series of years and the wood becomes of inferior quality. Hence the mode of production that protects the tree is in the long run the more economic one2).
In the French Dauphine and about Briancon, the balsam is obtained in a similar manner. However, the series of holes are bored in a straight line from below upwards, and each opening is provided with a short tube of tin or wood. When the first flow of balsam ceases the openings are closed with wooden stoppers, which are removed after two or three weeks to collect a second crop. The second flow is said to be greater than the first. The tapping is done each summer between March and September. Strong trees produce from 3 to 4 kg turpentine each year. After 40 to 50 years of such treatment the trees are exhausted3).
Inasmuch as there is no real demand for Venice turpentine oil, its distillation is not conducted on a large scale. The yield amounts to 13,5 to 15 p. c.
1) Bot. Zeitung 17 (1859), 329, 377.
2) Wesseley, Die Gsterreichischen A/pen/ander und ihre Forste. 1853. P. 369. - A. Tschirch and G. Weigel, Arch, der Pharm. 238 (1900), 387.
3) G. Planchon and E. Collin, Les drogues simples d'origine vegetale. Paris 1895. Tome 1, p. 70.
Properties1). d15o 0,865 to 0,878; aD - 8° 15' to - 11°2); nD20o= 1,46924; A. V. 0.; E. V. 5,9; soluble in 6 vol. and more of 90 p. c. alcohol. Distilled in a Ladenburg flask 60 p. c. come over between 157 and 161° (753 mm.), 20 p. c. between 161 and 164°, and 6 p. c. between 164 and 168°, residue 14 p. c.
Composition. Upon saturating the lower boiling fractions with hydrogen chloride, Fluckiger3) obtained a crystalline chlor-hydrate C10H16Hc1, from which the presence of a-pinene must be concluded.
Rabak4) describes a larch turpentine which he obtained in the following manner from specimens of Larix decidua cultivated in North America: In April several holes, one inch in diameter, were bored to the center of the trunk. These holes were stoppered with corks. In October of the same year the turpentine was collected. It was light yellow in color and viscid: d22o 1,0004; aD in 5 p.c. alcoholic solution +2° 20', hence [a]D + 46°29'; A.V. 60. Upon steam distillation it yielded 13,5 p.c. of a volatile oil with d22o 0,867 and aD + 20 16'. The principal constituent of the oil is a-pinene (m. p. Of the nitrol benzylamine 121°).