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ACTION OF NITRIC ACID ON RHUBARB. 
not only in appearance, but in the characters presented when 
examined in the manner already described. 
I feel fully justified therefore in the conclusion I have 
drawn, that a most ingenious but unwarrantable system of 
adulteration is adopted in the manufacture of cut isinglass, 
and I trust that this exposure will enable those who deal in 
isinglass to detect the imposition, if its practice should be 
continued. — Pharmaceutical Journal, May, 1850. 
ART. LVII. — ACTION OF NITRIC ACID ON RHUBARB ; AND 
PRODUCTION OF A NEW COLORING MATTER, ERYTH- 
ROSIN. 
By M. Garot. 
On adding four parts of nitric acid to one part of coarsely- 
powdered rhubarb, in a wide-mouthed, stoppered bottle, a 
brisk reaction speedily takes place, accompanied by the dis- 
engagement of nitrous gas, elevation of temperature, and 
swelling up of the mixture. This reaction commences 
almost immediately with indigenous rhubarb, but less ener- 
getically with the foreign varieties. A temperature of from 
60* to 70° Fah., however, is necessary to commence the 
action. 
After leaving the ingredients in contact for two days, the 
foreign rhubarb acquires a pulpy consistence and orange 
yellow color, the acid being almost entirely absorbed by the 
solid residue. The indigenous rhubarb, on the other hand, 
assumes the condition of a bright chrome-yellow pulp, float- 
ing on an acid liquor. 
On diluting the mixtures with a large quantity of water, 
straining through cloth, washing, pressing, and drying the 
solid residues, there remains from the indigenous rhubarb, 
a bright yellow, and from foreign rhubarb, an orange- 
