378 ODOROGRAPHIA. 



Russia Leather. 



The peculiar and much adinired aroma of so-called " Eussia 

 leather " is due to the employment in the process of dressing the 

 leather, of an empyreumatic oil, which is formed by the destructive 

 distillation of the bark of the White Birch, Betula alha, Lin. 



The extraction of Birch tar is an industry of some importance 

 in Kussia ; the process is said to be conducted in the following 

 manner : — An iron vessel is filled with bark and covered with a 

 close-fitting lid, through which is inserted an iron pipe. On this 

 is inverted a smaller iron vessel ; the rims are carefully fitted 

 together and w^ell-lated with clay. The two vessels are then 

 turned upside down, so that the one with the bark in it is upper- 

 most. The apparatus is half sunk in the ground, well-banked 

 with a mixture of sand and clay, and a wood fire is kindled around 

 it. When the distillation has continued long enough, the luting is 

 removed and the two iron vessels separated ; the lower one is found 

 to contain the tar and pyroligneous acid, the yield of tar being 

 about one-third by weight of the bark used. In some districts the 

 retorts are made of clay and the connecting pipes are of wood, but 

 the receivers are always placed in the earth. The crude tar is a 

 thick, black, empyreumatic fluid, which, when caused to cover in a 

 thin layer the side of a bottle in which it is contained, has a dark 

 brownish tinge. After a mere trace of it has been rubbed on the 

 hand, an odour like Eussia leather is perceptible. The Eussian 

 name for it, as pronounced by the natives, sounds to a person not 

 conversant with the Eussian language as " Dagget." On being 

 re-distilled, a reddish brown oil is obtained ; the yield being about 

 20 per cent. The distillers in Germany prefer the Polish to the 

 Eussian Birch tar. 



The phenols of Birch wood tar have been investigated by Max 

 Pfrenger (Archiv. f. Pharm., 29th December, 1890, p. 713), who 

 worked upon an Oleum hctiUini cethereum redijicatum obtained 

 from Schimmel & Co. The oil was a thin, light-refracting liquid, 

 of a yellow-brown colour, acid in re-action, and having the odour of 

 Eussia leather; sp.gr. at 15" C, 0-956. After removal of free 

 acid by treatment with soda solution, the oil was repeatedly shaken 

 with caustic potash solution, the dark brown phenylate layer that 

 formed on standing, separated and decomposed with dilute 

 sulphuric acid, and the liberated phenols, amounting to 43*9 per 



