^ESCULIN. 415 



sugar and saligenin (p. 315). When heated with dilute 

 hydrochloric or sulphuric acid, it yields sugar and 

 saliretin (p. 315). 



Tetracetyl-salicin, C 13 H 14 (C 2 H 3 0) 4 7 . Is obtained 

 by heating salicin with acetyl chloride or acetic anhy- 

 dride. Colorless, lustrous needles ; but slightly soluble 

 in water, ether, and cold alcohol, easily soluble in hot 

 alcohol. 



Benzoyl-salicin (Populin), C 20 H 22 8 + 2H 2 = 

 C 13 H 17 (C 7 H 5 0)0 7 + 2H 2 0. Is contained in the bark and 

 leaves of Populus tremula, from which it may be pre- 

 pared in the same manner as salicin. It is formed to- 

 gether with di- and tribenzoyl-salicin by the action of 

 benzoyl chloride on salicin ; and by fusing salicin and 

 benzoic anhydride together. Small, colorless prisms of 

 a sweetish taste, difficultly soluble in cold water, more 

 easily soluble in hot water and in alcohol. When 

 boiled with baryta- water or milk of lime, it yields beii- 

 zoic acid and salicin. Dilute acids (but not emulsin), 

 resolve it into sugar, saliretin, and benzoic acid. 



Dibenzoyl-salicin, C 13 H 16 (C 7 H 5 0) 2 7 , and tribenzoijl- 

 salicin, C 13 H 15 (C 7 H 5 0) 3 7 , are formed from salicin to- 



ether with populin. They are white powders, insolu- 

 le in water, scarcely crystalline. 



Helicin, C 13 H 16 7 . Is formed together with nitro- 

 salicylic acid by the action of nitric acid (containing 

 hyponitric acid) on salicin. Small, white needles, diffi- 

 cultly soluble in water, more easily in alcohol ; fusing 

 point, 175. Ferments, dilute acids, and alkalies re- 

 solve it into sugar and salicylic aldehyde (p. 322). 



4. JEsculin. 



Occurrence. In the bark of ^Esculus hippocastanum, 

 and several other trees. 



Preparation. The bark of horsechestnut-trees is 



