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PHARMA COGNOSY. 
AMYLUM (Starch). 
The starch grains obtained from the fruits of wheat, 
corn and rice. The grains are separated from the cells, 
purified in various ways, and subsequently washed with 
large quantities of water. In the U. S. Pharmacopoeia 
cornstarch alone is recognized. 
Description. — Corn Starch. — In fine powder or irregu- 
lar angular, white, inodorous, tasteless masses; grains 
somewhat spherical, but usually polygonal, with a 
lenticular, circular or triangular point of origin of 
growth, about 10 to 25 g in diameter. 
Wheat Starch. — Usually in a fine powder consisting 
of nearly spherical or ellipsoidal grains with point of 
origin of growth and lamellae more or less indistinct, 
about 15 to 40 g in diameter. 
Rice Starch. — Usually in a grayish- white powder con- 
sisting of minute angular grains about 5 to 8 ^ in 
diameter and with point of origin of growth and 
lamellae indistinct. 
Starch is insoluble in cold water or alcohol, but 
forms a white jelly when boiled with water, which, 
when cool, gives a deep-blue color with iodine and 
should give a neutral reaction to litmus paper (commer- 
cial cornstarch is usually alkaline); ash not more than 
1 per cent. 
ACACIA (Gum Arabic). 
A dried gummy exudation from the stem and 
branches of Acacia Senegal and probably other species 
of Acacia (Fam. Leguminosae), trees indigenous to 
Northern Africa. The gum arises as a decomposition 
product of the walls of some of the cells of the bark, 
and exudes spontaneously, or the trees are incised, 
which increases the production of gum. The more or 
less hardened pieces are collected and then sorted into 
different grades, the market supplies being obtained 
