PLANT PRODUCTS USED IN MANUFACTURES 525 



From the buckthorn family are obtained yellow and green 

 dyestuffs, known, respectively, as Persian berries and Chinese 

 green indigo. 



Varnishes of great value are yielded by trees of the pea family 

 (copal varnish) and of the sumach family (Japanese lacquer). 



Tanning is largely 

 carried on by aid of 

 the bark of several 

 species of oak, of 

 which the black oak 

 and the Spanish oak 

 are two of the most 

 used American spe- 

 cies. Hemlock bark 

 and the leaves and 

 young twigs of Sicil- 

 ian and American 

 species of sumach 

 are also used for 

 tanning. Other sub- 

 stances employed for 

 the same purpose are 

 catechu, derived from 

 a species of acacia, 

 and gambier, derived 

 from the evaporated 

 sap of a tree of the ^ IG- ^^* ^ twig f ^ ne South American rubber 



tree (Hevea) 



madder family, a na- 

 tive of the East Indies. After Schmidt 



India rubber is manfactured from the sap of several tropical 

 trees and lianas. The principal, one of these is the Para rubber 

 tree (Hevea) of the spurge family. 



Gutta-percha is produced by trees of the star apple family 

 (Sapotacece) of the Malay Archipelago, a family of much eco- 

 nomic importance. 



