OBSERVATIONS ON COLLODION. 
293 
net in 1833, who first prepared it by precipitation from a 
solution of starch in nitric acid, by adding water; it is very 
soluble in ether. Pyroxyline, is believed to be identi- 
cal with Schonbein's gun cotton, and is insoluble, or 
nearly so, in ether. Etheroxyline, is completely soluble 
in ether, with a small proportion of alcohol, and in solu- 
tion is the substance recently named Collodion. 
Whether these compounds are different in composition, 
or what are the circumstances which give rise to their dif- 
ferent reactions, is a question which is yet to be determined. 
Prof. Schonbein asserts that pyroxyline differs from xyloi- 
dine in its being insoluble in acetic acid • while Bracconet 
maintains the identity of all the compounds of cellulose 
with nitric acid. Etheroxyline would seem to resemble it 
still more, though I have never yet met with an article per- 
fectly soluble in ether which possessed the property of ex- 
ploding without the least solid residue, which is the case 
with gun cotton of good quality. The existence of these 
three substances may perhaps account for the fact that our 
specimens of prepared cotton differ so much in their proper- 
ties according to circumstances. When the nitric acid is 
too weak, it dissolves the cotton into an amorphous 
substance, extremely soluble in ether, but destitute of ad- 
hesiveness, which appears to correspond with xyloidine. 
When the acid is stronger, and contains an abundance of 
the nitrous acid fumes, we have either pyroxyline or ether- 
oxyline, according as the action has been more or less vio- 
lent, both having precisely the same texture and appear- 
ance, though differing in their solubility and in the com- 
pleteness of their dissipation by heat. 
Pyroxyline having been analyzed, is stated to contain — 
Lignin, 39.25 
Nitric Acid, .... 60.75 
100 
25* 
