ACTION OF NITRIC ACID ON RHUBARB. 
243 
colored powder. Indigenous rhubarb yields from S. 5 to 10 
per cent., and foreign rhubarb from 15 to 20 per cent, of this 
product. 
The author proposes the name Erythrosin for this pro- 
duct, in consequence of the property it possesses of being 
reddened by alkalis. 
Properties of Erythrosin. — After being dried, erythrosin 
is in the form of a yellow or orange agglomerated powder, 
which acquires a shining appearance on being pounded in 
a mortar. It is perfectly tasteless; the odor slightly aro- 
matic and nitrous, arising probably from the presence of a 
little nitrous acid in combination, which washing will not 
remove. 
•fiction of Heat, — When exposed to the action of heat in 
a glass tube, abundance of yellow vapors of rhabarbaric 
acid are given off, which condense into a yellow crust on 
the sides of the tube, and leave a white residue of lime, 
which is more abundant in the erythrosin from foreign than 
from indigenous rhubarb. 
Action of Water.— Cold water has but little action on 
erythrosin, merely acquiring a slight yellow color; but if it 
be boiled, the liquid acquires a reddish amber color, and 
becomes slightly acid. This acidity appears to arise from 
the presence of a little nitric acid, not previously removed 
by.the washings; for it cannot be attributed to rhabarbaric 
acid, the quantity of which is so small, as scarcely to redden 
potash. When evaporated to a certain extent, the liquor 
deposits a gelatinous matter having all the characters of 
pectin. 
Action of Alcohol. — Cold alcohol has little action upon 
it: it acquires an amber color, which becomes deeper on 
the application of heat, and finally assumes the reddish- 
yellow color of Malaga wine. After treating it seven or 
eight successive times with boiling spirit, all soluble matter 
is removed, and the solutions all redden litmus paper. 
On evaporating the alcoholic solution, a yellow flocculent 
