290 
OBSERVATIONS ON COLLODION. 
pletely, but was destitute of any adhesive property, while 
at others it yielded a product completely answering the end 
desired. Under these circumstances the essay referred to 
was written, rather with a view to draw attention to the 
chemical and pharmaceutical relations of this new and in- 
teresting compound, than in the belief that our knowledge 
of the subject would justify an attempt to prescribe a per- 
fect formula for its preparation, or fully to describe its pro- 
perties and habitudes. 
Having since prepared the collodion very frequently to 
meet a constant and increasing demand, and having ob- 
served particularly the precautions necessary to insure suc- 
cess, we have adopted the conclusion that the recipe then 
given, modified by changing somewhat the proportion of 
cotton to the acids, is the best adapted to its successful 
preparation of any that has been published. The formula 
of M. Mialhe, published in this Journal, (vol. xv., p. 42,) 
has been recently very generally adopted, as giving a more 
uniform and certain product, but we have found it to fail as 
frequently as the other, and to be much more inconvenient 
in its execution. It is impossible to make more than a 
very small quantity at one time, and the operator is ex- 
posed to the acid fumes while stirring the cotton with the 
semifluid mass, to a very inconvenient and even dangerous 
extent. The process of washing the product is also more 
inconvenient and tedious by this than by the preceding plan. 
Having stated thus much, I will proceed to give the 
two formulae, modified so as to correct the error in the 
proportion of cotton to the acids in the first, and what must 
have occurred to all who have used it, as an excess of pre- 
pared cotton to ether in Mialhe's; the latter has also 
been changed so as to adapt its phraseology to that of our 
officinal formulae. 
No. 1. Take of Fuming Nitric Acid, sp. grav. 1.48, and 
Sulphuric Acid, each 4 fluid oz. 
Cleansed and Bleached Cotton, i oz. 
Sulphuric Ether, U. S. P., 4 pts. 
