270 MATERIA MEDIC A AND THERAPEUTICS. 



favourite constituent of some purgative pills and aperient 

 draughts for chronic biliousness and gouty dyspepsia. 



Catechu Pailidum PALE CATECHU. An ex- 

 tract of the leaves and young shoots of Uncaria 

 Gambir, Prepared at Singapore and in other places 

 in the Eastern Archipelago. 



Characters. In cubes, about an inch in diameter, externally 

 brown, internally ochrey-yellow or pale brick-red, breaking 

 easily with a dull earthy fracture. Taste bitter, very astringent, 

 and mucilaginous, succeeded by slight sweetness. Entirely 

 soluble in boiling water. The decoction when cool is not 

 rendered blue by iodine. 



Composition. Catechu chiefly contains a crystalline bitter 

 substance, catechin or catechuic acid, CjsH^Og, probably itself 

 inactive ; and catechu-tannic acid, the active principle, isomeric 

 with it, and into which it is rapidly converted by boiling or by 

 the action of saliva, with the development of a red colour. 

 Both catechuic and catechu-tannic acids give a green precipitate 

 with persalts of iron. 



Incompatible*. The alkalies, metallic salts, and gelatine. 



Dose. 10 to 30 gr. 



Preparations. 



1. Infusum Catechu. 1 in 27. Dose, 1 to 2 fl.oz. 



2. Pulvis Catechu Compositus. Catechu. 4 : Kino, 2; Ehatany, 



2 ; Cinnamon, 1 ; Nutmeg, 1. Dose, 20 to 40 gr. 



3. Tinctura Catechu. 1 in 8. Dose, to 2 fl.dr. 



4. Trochisci Catechu. 1 gr. in each. Dose, 1 to 6. 



ACTION AND USES. 



Catechu acts like tannic acid, and is used for the same 

 purposes. It is a favourite astringent application to sore 

 throat in the form of the lozenge, and the compound powder 

 and tincture are very commonly prescribed for diarrhoea. 



Caffein. (Not Officinal] An alkaloid obtained 

 from Coffea arabica, the coffee plant ; from Thea 

 sinensis, the tea plant (nat. ord,, Camelliaceae) ; from 

 Ilex paraguay ensis, Mate, or Paraguay Tea (nat. ord., 

 Aquifoliacse) ; and from Guarana. (See page 211.) 



Characters. Caffein, C 8 H ln N 2 O 4 , occurs in fine long silky 

 white prisms, soluble in water, with a bitter taste. It is a 



