ARAROBA 



463 



freeing it from the debris present, drying and powdering ; but the 

 purification is more generally effected by grinding the crude drug, 

 drying it, boiling it with benzene, and filtering ; the. hot benzene 

 solution deposits on cooling a yellow, crystalline powder which forms 

 the chrysarobin of commerce. This is a yellow, crystalline, tasteless, 

 and inodorous powder, soluble in hot chloroform and benzene, almost 

 entirely soluble in hot alcohol, very sparingly and incompletely soluble 



p...... 



-p 



FIG. 241. Araroba. Portion of a transverse section 

 of the wood of Andira Araroba, near to a cavity 

 filled with araroba. S, vessels ; I, wood fibres ; 

 2>,Vood parenchyma ; ra, medullary rays. Nearly 

 all the elements contain a dark substance, which 

 in the upper part forms a dense mass, x (omitted 

 from the illustration). Magnified. (Vogl.) 



in petroleum spirit, and practically insoluble in water. Hot solution 

 of potash dissolves it almost entirely. To solution of ammonia it 

 imparts at first a slight pink tinge ; this colour, however, quickly 

 deepens owing to oxidation of the chrysarobin (which is insoluble 

 in ammonia) to chrysophanic acid (which is soluble). 



Purified araroba melts when heated, gives off yellow fumes, and 

 finally burns, leaving not more than 1 per cent, of ash. 



Crude araroba, as imported, often contains from 15 to 30 per cent, 

 of water, which appears to be added to prevent the irritating dust from 

 rising ; it may yield from 50 to 75 per cent, of purified araroba. 



