652 BOTANY AND PHARMACOGNOSV. 



Persian or Syrian Tragacanth. In flattened, lamellated, 

 ribbon-like pieces, 0.5 to 2.5 cm. long, about i cm. wide and from 



1 to 3 mm. thick, irregularly oblong, more or less curved ; exter- 

 nally nearly colorless or pale yellowish, with numerous concentric 

 ridges or lamellae ; translucent ; fracture short, tough, horny, ren- 

 dered more easily pulverizable by a heat of 50 C. ; inodorous ; 

 taste insipid. 



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 bassorin ; a carbohydrate apparently in the nature of 

 an insoluble compound of arable (gummic) acid, which swells in 

 water but is insoluble in it; aracin, 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 iodine ; 

 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 



2 or 3 days (while Indian gum becomes slimy and stringy). 



Indian gum is obtained from Cochlospermnm gossypiiini 

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

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

 Sterciilia iircns, a tree growing in Africa and Australia. The 

 gum occurs in vermiform or rounded tears, with a dull, rough 

 surface and uniform vitreous fracture. For detection in 

 tragacanth, see above. 



Ghatti gum is also called Indian gum (p. 644). 



Sarcocolla is a gummy exudation of Pencra SarcocoUa and 

 P. mucronata (Fam. Penasacese, one of the Myrtiflorae), small 

 shrubs indigenous to Southern and Central Africa. The gimi 

 occurs in small, globular, yellowish-red or brownish-red friable 

 grains, which are often agglutinated into masses and admixed 

 with a few hairs. Sarcocolla 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. 



