234 
ON THE PREPARATION OF COLLODION. 
any experiments having been made on the subject, and 
therefore trust my experience may be of some interest. 
In V Union Medicate of the 7th September last, M. Mal- 
gaigne says, " The American Journal of the Mediral Scien- 
ces contains an extract from a letter by Mr. Maynard, con- 
taining a formula for the preparation of collodion, which 
might be supposed to be authentic. According to this for- 
mula the cotton is to be treated with nitric and sulphuric 
acids, dried, and dissolved in pure sulphuric ether. " 
" Upon reading this letter, 1 lost no time in applying to 
M. Foy, Pharmacien to the Hopital St. Louis, to obtain a 
quantity of this liquid, but he in vain attempted to prepare 
it either from the acids united or the nitric alone, I after- 
wards prevailed on MM. Dublanc and Mialhe to under- 
take its preparation, but they were not more successful, and 
it was evident that a formula which failed successively in 
the hands of three such distinguished Chemists was incor- 
rect ; M. Mialhe, however, undertook, at my request, the 
investigations which led him to the discovery of the method 
by nitrate of potash and sulphuric acid, which has always 
proved successful. The cotton so prepared does not defla- 
grate as usual, and leaves behind a carbonaceous residue on 
combustion. The explosive cotton he found insoluble in 
ether. 
In the same periodical, shortly after, appeared a notice 
from M. Salmon, Surgeon to the Hotel Dieu, of Chartres, 
who states that "contrary to the experience of MM. Foy, 
Dublanc, and Mialhe, I assert that collodion may be easily 
prepared by dissolving gun-cotton made by the mixed acids 
in sulphuric ether. I have always prepared the adhesive 
liquid by the method of the American author. The prepa- 
ration of collodion, according to the process of MM. Millon 
and Gaudin, revived by M. Mialhe, is not always practica- 
ble, and is liable to great variations from the inconstancy of 
the product." 
On the above, Soubeiran, in the same journal observes, 
