ON THE PREPARATION OF COLLODION. 
235 
i( I, like many others, have attempted to operate with a 
mixture of the monohydrated nitric and sulphuric acids. I 
have employed them sometimes with equal weights, at 
other limes with equal volumes, and immersed the cotton 
for different periods from three minutes to an hour, and I 
have never found it to dissolve in ether. I do not, however, 
contend that it is impossible to do so, but I must think the 
other a more certain method, though the employment of 
the mixed acids has the advantage of convenience over the 
other. — P.T., Vol. iii., No. cvii., p. 665. 
Professor Simpson states that " usually an ounce of strong 
sulphuric ether will dissolve thirty grains or more of gun- 
cotton in the course of a few hours ; but to form a com- 
plete pulp it will require to stand for a day." — Pharma- 
ceutical Journal^ Vol. viii., No. ii., p. 86. 
My own experience coincides with that of M. Salmon. 
I take equal volumes of strong sulphuric and strong fuming 
nitric acids, mix them in a mortar or other convenient ves- 
sel, then immerse finely carded cotton in small portions, 
allowing each to remain about one minute, then plunging 
it into a large quantity of water, and teasing it out with a 
glass-rod, so as to become as loose as possible, yellow fumes 
arise from the cotton, and are washed away, and it is then 
perfectly white. This is then well washed from acid and 
dried, and it then instantly and perfectly dissolves in 
commercial sulphuric ether, forming either a semi-solid 
jelly or thick liquid, according to the quantity of ether 
added. This is the constant and uniform result of several 
experiments I have made. 
This cotton is also highly explosive, and leaves no car- 
bonaceous residue, when fired. 
The sources of fallacy, I imagine, are, either from em- 
ploying weak acids, too long immersion, or ether of high 
rectification. The latter should not contain water, but suffi- 
cient alcohol to reduce its specific gravity to about 760° or 
770°. Its solvent action is then instantaneous, and not as 
Simpson states, from three hours to a day ! 
