236 
ON THE PREPARATION OF COLLODION. 
I consider this process to be superior on many accounts 
to that of Mialhe. It is more readily prepared, and requires 
less washing than when entangled with sulphate of potash. 
It is explosive, and therefore answers both purposes, i 
have dissolved some with equal readiness that has been thus 
prepared more than a month ; so that it may be convenient 
to keep the cotton prepared, and dissolve small quantities 
as frequently as required, and thus obviate the loss by 
vaporization which ensues on keeping a stock of the solution 
prepared. 
Ivvas led to make these experiments for Mr. Higginsom 
Surgeon of this town, who recently exhibited at the Literary 
and Philosophical Society, some evaporated collodion under 
the microscope, which had all the appearance of distinct 
and definite acicular crystals; and Mr. H. stated that he had 
made very frequent examinations, and observed an unifor- 
mity in their shape and arrangement, which convinced him 
that these were crystals of collodion, and not filaments of 
cotton. 
It was suggested that there might be minute crystals of 
nitrate or sulphate of potash, and I therefore undertook to 
prepare some collodion without any salt to interfere : in this 
1 have succeeded ; but have not yet heard the result of Mr. 
Higginson's more recent investigations. 
Allow me to caution those who are not in the habit of pre- 
paring gun-cotton, as to its highly explosive nature. The 
gaseous results of combustion, which of course at once occup y 
a very large space in the air, are thus given off at a very 
high temperature, so as to possess the property of inflaming 
other portions of cotton at a very considerable distance; 
and thus, on trying whether the cotton is sufficiently dry, 
by exploding a small portion, it should be removed for some 
distance from the remainder, or the whole will ignite, and 
if the operator be standing over it, his face may be severely 
burned, though no flame reaches it, the resulting gases being 
quite capable of blistering the skin. It is better to operate 
on small portions at once. — London Pharm, Jour. 
