EXUDATIONS, JUICES, ETC. 
233 
from Egypt by way of Alexandria, from the Soudan 
by way of Suakin, and from Senegambia by way of 
the port of St. Louis. 
Description. — In roundish tears of variable size, or 
broken into angular fragments ; externally whitish or 
yellowish white; translucent; very brittle, with a glass- 
like, sometimes iridescent fracture ; nearly inodorous ; 
taste mucilaginous. 
Acacia is not soluble in alcohol, but is completely 
soluble in water; the solution gives an acid reaction with 
litmus paper, yields a gelatinous precipitate with basic 
lead acetate solution (Ghatti gum giving but a slight 
precipitate), ferric chloride or concentrated solution of 
sodium borate, and does not give a bluish or reddish 
color with iodine (absence of starch or dextrin), or a 
brownish-black precipitate with ferric chloride (absence 
of Mesquite gum), and does not reduce Fehling’s solu- 
tion (absence of gums containing sugars). 
The powder contains few or no altered or unaltered 
starch grains or vegetable tissues. 
Constituents. — A crystalline glucoside, which is 
apparently Arabic acid in combination with calcium, 
magnesium and potassium, and which constitutes the 
greater part of the gum ; ash 3 to 4 per cent. 
Adulterants. — Various species of Acacia indigenous 
to Tropical Africa and Australia, as well as Anogeissus 
latifoli a(Fam. Combretacese) (the latter being the source 
of the so-called Ghatti gum), yield gums which, while 
resembling true acacia, do not respond to the tests 
given above. 
The powder, while sometimes adulterated with dex- 
trin and rice starch, is more frequently mixed with 
inferior gums, especially the Mesquite gum, which is 
yielded by Prosopis glandulosa, a tree indigenous from 
Mexico to Colorado. 
