ACTIONS AND USES 643 



and Burmah, is derived from several trees, largely from 

 the Acacia catechu, a native of India and Africa. The 

 Acacia suma, a large tree growing in Bengal, Burmah, and 

 Southern India, has a white bark used for tanning, and red 

 heart-wood, from which catechu is also made. The wood of 

 these and of other trees is cut into chips and boiled with 

 Avater, the decoction concentrated either by fire or the heat 

 of the sun, and the extract cut or moulded into square cakes 

 or masses. 



The pale and black catechus are very similar in com- 

 position and properties ; are porous and opaque ; brittle, 

 breaking with a granular fracture ; under the microscope 

 exhibit minute, needle-b'ke crystals ; are without odour, 

 but have a sweet astringent taste. They are soluble in 

 alcohol and ether, partially soluble in cold water, entirely 

 dissolved by boiling water, with which they form red-brown 

 solutions. They consist of about 40 per cent, of catechu- 

 tannic acid, which is soluble in cold water ; and of catechin 

 or catechuic acid (C 13 H 12 5 ), a modification of tannic acid, 

 which deposits in acicular crystals from boiling watery 

 solutions of catechu, and is soluble in alcohol and ether. 

 They further contain the yellow colouring matter quercitin. 



ACTIONS AND USES. Catechu is astringent, acting by 

 contact only. It forms insoluble compounds with albumin 

 and gelatin, and, like other tannin-containing substances, is 

 used in making leather. It is less astringent than oak bark 

 or galls, but more astringent than kino, the inspissated juice 

 obtained from incisions made in the trunk of Pterocarpus 

 marsupium ; than rhatany, the dried root of Krameria 

 triandra or of K. argentea ; than logwood, the sliced heart- 

 wood of Hsematoxylon campechianum ; or than bearberry 

 or uva-ursi leaves. 



Catechu is administered to the several domestic animals 

 for the arrest of chronic catarrhal discharges and haemor- 

 rhage, especially from the throat and alimentary canal. 

 The insoluble catechin beneficially exerts its astringency on 

 the relaxed, over-secreting surfaces alike of the small and 

 large intestines. In persistent diarrhoea and in dysentery 

 it is conjoined with aromatics to allay flatulence ; with 

 opium to relieve irritability and spasm ; with alkalies, 



