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 ben- 

 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 tribenzoyl- 

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

 gether with populin. They are white powders, insolu 

 ble in water, scarcely crystalline. 



Helicin, C 13 II 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 JEsculus hippocastanum, 

 and several other trees. 



Preparation. The bark of horsechestnut-trees is 



