ARBUTIN. 419 



and the red precipitate then decomposed. The acid is 

 thrown down with the lead sulphide, and separated 

 from this by extracting with alcohol. Yellow prisms, 

 sparingly soluble in cold water, easily in hot water, al- 

 cohol, and ether. By boiling with acids and alkalies, 

 as well as by contact with a ferment contained in mad- 

 der, it is resolved into sugar and alizarin. In old madder, 

 as it is used in dying, this decomposition has already 

 partially taken place ; it is accelerated by treating the 

 madder with sulphuric acid (Garancin, a commercial 

 product, is madder which has been treated in this 

 way). 



Morindin, a body contained in the root-bark of Mo- 

 rinda citrifolia, is probably identical with rubianic acid ; 

 and the dye morindon, prepared from it by means of 

 sublimation, appears to be alizarin. 



9. Arbutin. 

 C 12 H 16 7 . 



In the leaves of the bearberry (Arbutus uva ursi\ 

 and of winter-green (Pyrola umbellatd). Long, color- 

 less, bitter tasting needles, which fuse at 170, the so- 

 lution of which is colored deep blue by iron chloride. 

 In contact with emulsin, and by boiling with dilute 

 sulphuric acid, it is resolved into sugar and hydroquinone 

 (p. 303), which is also formed by the dry distillation of 

 arbutin. Concentrated nitric acid converts it into 

 bright-yellow needles of dinitroarbutin, C 12 H 14 (N0 2 ) 2 7 

 + 2H 2 0. When chlorine is conducted into a watery 

 solution of arbutin, substitution-products of quinone 

 (p. 301) are formed. 



10. Fraxin. 

 C 32 H 36 20 . 



In the bark of Fraxinus excelsior and 2Esculus hippo- 

 castanum. Fine, fascicular needles ; slightly soluble in 



