ME. ABEL’S EESEAECHES ON GUN-COTTON. 
207 
No. 3. — The extracted gun-cotton first exhibited signs of change, and nitrous vapours 
were evolved more abundantly than from the original sample, which only afforded faint 
indications of nitrous acid after several hours’ heating. The latter had lost only 5*5 per 
cent, at the conclusion of the experiment, while the extracted gun-cotton had sustained 
a loss of 10 per cent. 
No. 4. — Signs of change were exhibited by both samples at the same time; faint 
yapours made their appearance after eight hours’ exposure to 100° C. Nitrous acid was 
afterwards somewhat more abundantly evolved from the extracted sample. The loss 
sustained by the latter after twelve hours’ heating was 5 per cent., that of the original 
gun-cotton was 4T per cent. 
In these experiments No. 1 sample, which contained the average proportion of matter 
soluble in alcohol existing in Waltham Abbey gun-cotton, and a comparatively very 
small proportion of matter soluble in ether and alcohol, was rendered very much less 
susceptible of change at 100° C., by extraction with the mixed solvents, while the other 
samples, apparently in consequence of the injury to the structure of the fibre resulting 
from the extraction of a comparatively considerable proportion of imperfectly converted 
gun-cotton by the ether and alcohol, were rendered somewhat more prone to change by 
the treatment received. 
Experiments 81, 82. — Two specimens of gun-cotton, selected from those which in 
preceding experiments had been found most susceptible of decomposition at 100° C., 
were digested for some time in dilute acetic acid, afterwards thoroughly washed, first 
in slightly alkaline water, and then in distilled water. By this treatment such mineral 
impurities as might have an influence upon the rapidity of decomposition of the gun- 
cotton were removed. One-half of each sample was digested for twenty-four hours with 
ether and alcohol, afterwards washed with the mixture, and dried. The samples thus 
treated were exposed to 100° C. in a water-bath, side by side with corresponding quan- 
tities of the same specimen which had simply been extracted with acetic acid. The 
results observed were as follows : — 
No. 1. 
No. 2. 
Treated with acetic 
acid only. 
Treated with ether 
and alcohol. 
Treated with acetic 
acid only. 
Treated with ether 
and alcohol. 
Indications of change observed after 
first exposure to 100° C. 
35 minutes. 
7i hours (3 hours on 
the second day). 
30 minutes. 
3 h 45 m , very faint. 
Loss ofweight after 4-^ hours’ exposure 
to 100° O. 
17 9 per cent. 
2 3 per cent. 
20 per cent. 
1 per cent. 
The very marked difference in the stability of these specimens (which contained only 
very small proportions of soluble gun-cotton), when exposed to 100° C. in the two different 
conditions, appears to afford strong evidence that the abstraction of the matters soluble 
in ether and alcohol greatly increases the stability of the gun-cotton. The next-following 
experiments show, on the one hand, that this difference does not appear ascribable to 
the removal of the soluble gun-cotton from the trinitrocellulose, and indicate, on the 
2 f 2 
