GAMBIER 443 



Gambler of good quality is almost entirely soluble in boiling water, 

 and yields not less than 80 per cent, to alcohol. 



The filtrate from the alcoholic solution, made strongly alkaline 

 with solution of potash and shaken with petroleum spirit, imparts to 

 the latter a brilliant green fluorescence, a reaction which is charac- 

 teristic of gambier. 



A little of the powdered drug mounted in water and examined 

 under the microscope exhibits numerous minute acicular crystals 

 (of catechin), but should be free from starch. The residue left after 

 extraction with alcohol may also be tested for starch. The ash should 

 not exceed 5 per cent. 



Constituents. Gambier consists principally of catechin and 

 catechutannic acid, these two substances in varying proportions 

 constituting together in good specimens over 60 per cent, of the drug ; 

 the percentage of catechin varies from 7 to 33 per cent., that of 

 catechutannic acid from 22 to 50. These figures, however, vary 

 with the care with which the drug has been prepared. Brown 

 substances, rubinic and japonic acids, of unknown chemical nature 

 are also present. 



Catechin, C 16 H 14 6 ,4H 2 0, forms white, silky, acicular crystals with an astrin- 

 gent taste ; "it is sparingly soluble in cold but freely in boiling water, the solution 

 giving an intense green colour with ferric salts. In the presence of caustic 

 alkalies and water, catechin readily absorbs oxygen and yields a black dye ; 

 with carbonated alkalies the colour is red. Cotton may be dyed brown by 

 steeping in a hot solution of gambier containing a little copper sulphate and 

 then immersing it in a hot solution of potassium dichromate ; the catechin is 

 probably first converted into catechu tannic acid and then oxidised to japonic 

 acid. Gambier also contains small quantities of a second catechin, C 15 H M O 6 , 

 differing from the foregoing in its melting point and crystalline form. 



Catechutannic acid has been obtained as a reddish, amorphous substance 

 easily soluble in cold water and in alcohol, the former being used to extract it 

 from the drug. It is apparently produced from catechin by loss of a molecule 

 of water, and itself yields an insoluble red substance, catechu-red, when boiled 

 with water or with dilute mineral acids. These three substances, catechin, cate- 

 chutannic acid, and catechu-red, appear therefore to stand in close relation to 

 one another, and the relative proportion in which they occur in the drug depends 

 largely upon the care with which it is manufactured, well-prepared gambier 

 containing most catechin. Hence commercial gambier may contain as much 

 as 50 per cent, of catechutannic acid, and as little as 7 per cent, of catechin. 



Trimble (1888) found in three samples of gambier the following 

 composition : 



Catechin . . . . . 7 to 19 per cent. 



Catechutannic acid . . . 33 to 47 



Gum . . ... . . .. . 10 to 16 



Ash 3 to 4 



Moisture . . . . . 9 to 11 



Colouring matter, &c. . . . 4 to 28 



