TRAtJA'CANTH 333 



spheroidal or ellipsoidal, from 0.003 to 0.015 mm. in diameter, a 

 few of the grains being swollen and more or less altered. 



Constituents. Bassorin (traganthin), 60 to 70 per cent, which 

 gives the mucilage made from this gum its peculiar density, and which 

 serves to distinguish it from acacia, which contains little or no gasso- 

 rin; a carbohydrate apparently in the nature of an insoluble com- 

 pound of arabic (gummic) acid, which swells in water but is insoluble 

 in it; arabin, about 10 per cent, soluble in water and probably formed 

 from traganthin; starch; ash about 3 per cent, of which one-half is 

 calcium carbonate. 



A solution of 2 gm. of gum tragacanth and 100 c.c. of water is 

 neutral in reaction to litmus; gives a blue color with iodin; froths 

 on shaking with an equal volume of a 5 per cent solution of potassium 

 hydroxide, becoming yellow on heating; darkens slowly when 2 per 

 cent of powdered borax is dissolved in it in the cold, but does not 

 change in consistency even on standing two or three days (while 

 Indian gum becomes slimy and stringy). 



Indian gum, or Karaya gum, is obtained from Cochlospermum gos- 

 sypium (Fam. Bixacese) and is used in India as a substitute for traga- 

 canth. This name is also applied to a gum obtained from Sterculia 

 urens, a tree growing in Africa and Australia. The gum occurs in 

 vermiform or rounded tears, with a dull, rough surface and uniform 

 vitreous fracture. Pieces of the gum, softened in water and mounted 

 in glycerin, show numerous threads of a granular substance, some- 

 times the hyphse of a fungus and chains of bacteria, and occasional 

 fragments of a yellowish-brown or reddish-brown color, containing 

 lignified wood fibers, a few rosette aggregates of calcium oxalate 

 from 0.020 to 0.030 mm. in diameter, and a few spheroidal starch 

 grains from 0.003 to 0.007 mm. in diameter. Although inferior to 

 Tragacanth, Karaya gum has valuable properties and its commerical 

 use should be extended. (See Ewing, Jour. A. Ph. A., 1918, 7, p. 787.) 



Ghatti gum is also called Indian gum (see Acacia). 



Sarcocolla is a gummy exudation of Pensea Sarcocolla and P. 

 mucronata (Fam. Penaeacese, one of the Myrtiflorse), small shrubs 

 indigenous to southern and central Africa. The gum occurs in small, 

 globular, yellowish-red or brownish-red friable grains, which are 

 often agglutinated into masses and admixed with a few hairs. Sar- 

 cocolla has a licorice-like taste. It is soluble in water and alcohol, 

 and contains an uncrystallizable principle, sarcocollin, having a taste 

 of glycyrrhizin ; a resin ; and a gum. 



Catechu. An extract prepared from the heartwood of Acacia 

 Catechu (Fam. Leguminosse, sub-fam. Mimosacese), a tree indigenous 



