CRUDE DRUGS. 667 



Allied Plants. — Black catechu is also extracted from the 

 wood of Acacia Sitma, of India. The barks of a number of spe- 

 cies of Acacia growing in Australia, and known as wattle 

 BARKS, are used in the preparation of an extract resembling black 

 catechu. The tannin of Acacia arabica and of several species of 

 CcEsalpinia yield on hydrolysis gallic and ellagic acids. 



A tannin resembling catechu is obtained from the bark of 

 Eugenia Smithii (Fam. Myrtaceas), of Australia. A catechu- 

 like extract is obtained from the bark of the Mahogany Tree 

 {Swietenia Mahagoni) , one of the Meliaceas, of the West Indies 

 and Peru. 



Adulterants. — On account of the inferior quality of black 

 catechu in recent years the pale catechu has superseded it, and is 

 the only kind recognized in the United States and British Pharma- 

 copoeias. 



Catechu is sometimes adulterated with other plant extracts, 

 various inorganic substances, and starch. 



An extract (known as Than), prepared from Terminalia 

 Oliveri (Fam. Combretaceae), a large tree growing in the dry 

 regions of the Irrawaddy Valley, is used to adulterate Catechu. It 

 contains a dark red coloring principle, but apparently no tannin, 

 although the latter has been reported as occurring to the extent 

 of between 14 and 68 per cent. 



ELASTICA.— CAOUTCHOUC, INDIA-RUBBER.— The 

 latex or milk-juice of Hevea braziliensis , and probably other spe- 

 cies of Hevea (Fam. Euphorbiacese), trees indigenous to Brazil 

 (p. 316). The milk-juice is obtained by making incisions in the 

 bark of the tree and is collected in small cups fastened to the 

 trees. This is then poured into a larger vessel in which is placed 

 a wooden paddle. The latter, with adhering latex, is dextrously 

 revolved in an open fire until coagulated, new material being added 

 from time to time until flask-shaped masses are formed, which are 

 then removed, and constitute the commercial article known as 

 " bolacho." The best grade, known as Para Rubber, is official. 



Description. — In elastic flask-shaped masses or pieces of 

 varying form and size ; light, floating in water ; externally brown- 

 ish to brownish-black ; internally brownish, consisting of a number 

 of thin, alternate light and dark layers, due to the superimposed 



