LARCH (VENICE) TURPENTINE FROM WESTERN LARCH 



{LARIX OCCIDENTAUS) 



By S. a. Mahood, 

 Chemist in Forest Products 



The oleoresin from larch trees was known to Europeans at an early 

 date. Pliny describes it as a honey-like resin that issues slowly from 

 the larch tree but never becomes dry. It was first used by artists in 

 the preparation of their colors and also as a finish on paintings to 

 bring out the colors and to protect them from dust and dirt. It is 

 still used in the manufacture of artists' colors, but is now employed 

 more extensively in making varnishes, sealing wax, fly paper, patent 

 leather, porous plasters, and certain paints and pharmaceutical prepa- 

 rations. The name "Venice" or "Venetian turpentine" came into use 

 because the oleoresin was formerly exported exclusively from Venice. 



The oleoresin is obtained from bore-holes made in the trunk of the 

 European larch {Larix decidua Mill; L. europae De Candolle), w^iich 

 is grown for resin-producing purposes in the Tyrol in Piedmont, and 

 in France in the vicinity of Briancon. The method of tapping ^ is 

 based on the fact that the resin tends to collect in the heart of the 

 tree ^ and often fills the cavities made in the trunk by frost. Early in 

 the spring one or two holes, 2.5 to 3.8 cm. in diameter and horizontal 

 or nearly so, extending to the center of the tree and placed about 30 

 cm. from the ground, are bored with an auger in mature trees about 

 100 cm. in girth. The holes are carefully cleaned and then closed 

 with a dry larch plug to prevent loss by evaporation. In the autumn 

 the cavities are emptied by means of an iron scraper. After the second 

 or third collection the holes are widened to 4 cm. In some sections 

 the holes are not plugged, but wooden tubes are inserted in the open- 

 ings and the resin is allowed to flow through them into suitable 

 receptacles.^ The yield averages about 200 gm. per tap, and the product 



'"Die osterreichischen Alpenlander und ihre Foreste," p. 369; Archiv der 

 Pharn acie (1900), p. 289. 

 " Botanische Zeitung vol. 17, pp. .329 and 377. 

 ■" Duhamel, "Traite des arbres" vol. ii, p. 35.5. 



274 



