666 BOTANY AND PHARMACOGNOSY. 



Jaffarabad Aloes is a vitreous variety obtained from the 

 East Indies and is exported from Bombay. It occurs in circular, 

 flattened cakes, of a deep black color externally, and with a black, 

 glossy, slightly porous or somewhat laminated fracture. It yields 

 13 to 20 per cent, of aloin, which is apparently chiefly barbaloin, 

 and gives a deep crimson color with nitric acid. 



CATECHU. An extract prepared from the heartwood of 

 Acacia Catechu (Fam. Leguminosge), a tree (p. 294) indigenous 

 to India and Burmah, and from the leaves and twigs of Uncaria 

 (Ourouparia) Gambir (Fam. Rubicacese), a climbing shrub or 

 liane indigenous to Malacca, Java and Sumatra and mostly culti- 

 vated near Singapore, the former being known as " black catechu " 

 or " cutch," and the latter as " pale catechu," " gambir," or " terra 

 japonica." These extracts are prepared by boiling the parts of 

 the trees and shrubs yielding them with water, evaporating the 

 strained liquid to a syrupy consistence and allowing it to harden. 



Black Catechu. In irregular masses, with fragments of 

 leaves or mats upon the outside, dark brown, somewhat shiny; 

 brittle, more or less porous internally ; odor slight ; taste astrin- 

 gent and sweetish. 



Catechu is somewhat soluble in cold water, the undissolved 

 portion containing acicular crystals of catechin and cr}'stals of 

 another substance resembling octahedra (Fig. 275, A), but aniso- 

 tropic ; almost entirely soluble in boiling water, the solution giving 

 an acid reaction, a dense precipitate with copper sulphate and a 

 greenish-black precipitate with dilute ferric chloride solution ; 

 not less than 70 per cent, should be soluble in 90 per cent, alcohol. 

 Few or no starch grains or vegetable tissues should be present, 

 and the ash should not be more than 5 per cent. 



Gambir or Pale Catechu. Usually in more or less porous 

 irregular cubes, about 25 mm. in diameter ; externally dull red- 

 dish-brown ; friable ; internally paler, consisting chiefly of micro- 

 scopic crystals when examined in a drop of oil ; odor slight ; 

 taste bitter and very astringent. The aqueous solution gives an 

 intense green color with dilute ferric chloride and does not yield a 

 precipitate with copper sulphate solution. (See also Fig. 275, B.) 



Constituents.- -Catechutannic acid, 25 (black catechu) or 

 22 to 50 per cent, (pale catechu), giving a green color and pre- 



