462 RESINS 



acid value is about 90, but the determination is unsatisfactory, as 

 the end-reaction is indefinite. Guaiacum resin in other resins may 

 generally be detected by the ferric chloride reaction. 



Peruvian guaiacum is brownish and aromatic, and is used in 

 perfumery ; its botanical origin is unknown. 



ARAROBA 



(Goa Powder) 



Source, &c. Araroba, or, as it is often termed, Goa powder, is a 

 substance found in cavities in the trunk of Andlra Araroba, Aguiar 

 (N.O. Leguminosce) , a large tree common in the damp forests of Bahia 

 (Brazil). 



This remarkable substance is found filling longitudinal fissures in 

 the trunk of the tree. From careful microscopical examinations 

 that have been made of the fragments of wood picked from the crude 

 drug, it would appear that the walls of both parenchymatous and 

 prosenchymatous cells, as well as those of the vessels, undergo a 

 complete change, by which they are converted into a yellowish, 

 powdery, substance, araroba. This change is observable first in the 

 secondary thickenings of the cell- wall, but afterwards the cell- walls 

 themselves break-down, thus forming cavities of considerable size 

 which are filled with the araroba. The exact nature of the change 

 of the influences that induce it, and the manner in which it is effected, 

 is unknown ; it appears to be a pathological not a normal physiological 

 process. 



Araroba is collected by felling the tree, sawing the trunk into 

 lengths, and splitting these longitudinally. The yellowish powder is 

 then scraped out with the axe, by which means numerous splinters 

 of wood and other debris are simultaneously removed. It is exported 

 in that crude condition, and may be purified by sifting it as free as 

 possible from fragments of wood, drying, and powdering it. The drug 

 appears to have been long known to the natives of Brazil as a cure for 

 certain skin diseases. In 1864 Kemp drew attention to the Goa powder 

 that was used in India for similar purposes, and this was proved in 

 1875 to be identical with the araroba of the Brazilians. 



Description. The crude drug, as imported, consists of a brownish 

 yellow or umber-brown powder mixed with numerous small and large 

 fragments of wood. Microscopical examination of the powder shows 

 the presence of numerous minute prismatic crystals, and granular, 

 amorphous matter accompanied by vegetable debris. The smoothed 

 transverse surfaces of the larger fragments of wood show thin, yellow, 

 medullary rays, vessels, and here and there yellow masses (of 

 araroba). As already observed, it is sometimes purified by simply 





