246 
SUBSTANCE ANALOGOUS TO GUN COTTON. 
by precipitation, and having evaporated the glycerine to one- 
half, I found no difficulty, though great care was necessary 
to prevent the rising of temperature. Whenever the tem- 
perature rises above a certain point, an intense chemical 
action takes place, and a dense cloud of nitrous acid fumes 
is thrown orT. Whenever this improper action takes place 
the capsule will be found to contain a substance resembling 
molasses both in color and consistence, soluble in alcohol 
and water, and having a sour and bitter taste, and an odor 
resembling somewhat that of burnt sugar. In one or two 
instances, the diminution of the nitrous acid fumes was 
preceded by a distinct explosion, and in one instance the 
contents of the capsule were thrown in all directions. 
The acids are to be poured into the capsule, to be agi- 
tated for a few moments so as to mix them intimately, and 
allowed to stand until they are cooled down to the proper 
point. The prepared glycerine is then to be added slowly, 
and the mixture must be constantly stirred. It gradually, 
becomes thicker, and soon resembles honey both in color 
and consistence. It is now to be poured into water, and 
the substance sought for will, after a short time, be found in 
small opaque globules, resembling very much the globules 
of oil in an emulsion, at the bottom of the vessel. After 
having been thoroughly washed, it may be freed from 
water by means of the sulphuric acid, as recommended by 
Mr. Sobrero, or by means of a test tube having a very small 
aperture at the bottom ; the substance being heavier than 
water, will of course pass off first. Care must be taken to 
prepare it only in small quantities, as explosions are very 
liable to occur, causing, of course, loss both of time and 
materials. 
What the precise chemical nature of this substance may 
be, I am at present unable to state. My first impression 
was, that it was a nitro-sulphate of glycerine, but I am now 
convinced that the glycerine undergoes a decomposition, 
and that a new substance is formed from the combination 
of its elements with those of the acids. 
