380 ODOKOGKAPHIA. 



mixed with alcoholic neutral lead acetate so long as a precipitate 

 is produced thereby. 



The mixture again heated to the boiling point is filtered, and the 

 filtrate is freed from lead by means of ammonium carbonate and 

 allowed to cool, whereupon it deposits a mass of crystals of 

 impure betulin, which may be purified by treatment with ether and 

 crystallisation from boiling alcohol. 



Pure betulin forms long, tliin, colourless prisms, which, when 

 dry, present the appearance of asbestos. It is inodorous and 

 tasteless. It melts at 258^ C. to a colourless liquid, which 

 solidifies in a glassy, amorphous mass ; at a somewhat higher 

 temperature it begins to sublime in long, extremely delicate 

 needles. When strongly heated it gives off' vapours smelling 

 strongly of Russia leather. It is insoluble in w^ater ; sparingly 

 soluble in cold alcohol, ether, chloroform and benzene, but fairly 

 soluble in the hot liquids. It dissolves also in glacial acetic acid 

 and in oil of turpentine. Its composition agrees with the formula 

 CggligoOg. Betulin yields by dry distillation a number of 

 volatile products, amongst which is one of thick oily consistence, 

 boiling at 243*^, of sp. gr. 0'951, and having the composition of 

 Ictyilin ankydrich OggHj^. 0, which is probably the principal 

 aromatic ingredient of Birch tar, from which the commercial oil 

 of Eussia leather is obtained. 



This oil must not be confounded with the Birch oil distilled 

 from the Betula lenta, L., sometimes called " Sweet Birch," Cherry 

 Birch and Mahogany Birch ; this oil is totally different in 

 character. (See " Gaultheria "). An oil is also distilled from the 

 leaves of the Birch and the young leaf-buds of the poplar. 

 See p. 345, 346. 



An oil is produced in Japan under the name '•' Matsu oil," which 

 is distilled from a tar of either the Finns Massoniana or P. 

 densiflora, and was at first thought to be derived from a Birch or 

 Beech tar. Both these pines pass under the name of " Matsu " in 

 Japan, so it is as yet uncertain which of them (or whether both of 

 them) furnishes the supply, but the oil differs greatly in physical 

 characters to the German oil ; it has a sp. gr. of 0*875, and 

 contains only 4 per cent, of phenols, having an agreeable guaiacol 

 odour ; the portion of the oil insoluble in alkalies boils for the 

 most part below 180^ (about 40 per cent, from 160^ to 170^, and 



