GAMBOGE 475 



It is occasionally formed whilst soft into cakes of various shapes 

 or into thick sausage-like masses, which are wrapped in leaves, the 

 impression of which they bear on their surface (Saigon gamboge). 



Description. The finest qualities of gamboge occur in rolls, 3 to 

 5 cm. in thickness, and from 10 to 20 cm. in length, nearly cylindrical, 

 solid or hollow in the centre, and marked externally with longitudinal 

 striations derived from the inner surface of the bamboos in which they 

 have been dried. The drug breaks easily, with a smooth, uniform, 

 conchoidal fracture, the freshly fractured surface having a dull gloss 

 and being of a rich reddish yellow or brownish orange colour. It is 

 easily reduced to a bright yellow powder, with little odour, but with 

 an acrid taste. 



Thin splinters mounted in oil and examined under the microscope 

 exhibit a ground-mass of gum in which numerous minute granules 

 of resin are scattered accompanied by occasional crystals of calcium 

 oxalate and starch grains derived from the incised tissues. 



Rubbed with the wet finger gamboge instantly forms a yellow 

 emulsion. It is almost completely dissolved by the successive action 

 of alcohol and water. The yellow emulsion yielded with water becomes 

 nearly clear and deep orange red on the addition of ammonia. 



Constituents. Gamboge consists essentially of a mixture of 70 to 

 80 per cent, of resin, with 15 to 25 per cent, of gum. 



.The resin, formerly known as cambogic acid, is soluble in alcohol, 

 ether, chloroform, benzene, petroleum spirit, &c., as well as in solutions 

 of alkaline hydroxides and carbonates ; from its alkaline solutions it 

 is precipitated by acids. From it three organic acids have been 

 separated, viz. a-, fi- and 7- garcinolic acids, the last named being 

 characterised by the red colour of even a very dilute alkaline solution. 



The gum is analogous to acacia gum ; it is laevorotatory and con- 

 tains an oxydase enzyme. 



j. Gamboge produces purging and in large doses vomiting. 

 It has been employed as a hydragogue cathartic, but is now seldom 

 used as a medicine. 



Adulterants. The chief adulterants are starch, inorganic matter 

 (such as sand, &c.), and vegetable debris. These are all easily detected 

 by their insolubility in alcohol and water used successively, or in 

 dilute ammonia. 



Varieties. Pipe gamboge, as above described, is the best variety. 



Inferior gamboge breaks with a dull, rough, granular fracture, and 

 the fractured surface, which often exhibits small cavities, is of a dark 

 brownish colour. 



Lump or cake gamboge consists of pipe gamboge bent and pressed 



