ME. ABEL’S KESEAECHES ON GUN-COTTON. 
231 
lively unstable organic impurities, and in a slight increase of the proportion of soluble 
gun-cotton *. 
The power possessed by carbonates to prevent or arrest the decomposition of gun- 
cotton when exposed to high temperatures, has been demonstrated in a striking manner 
by some experiments which have, at the same time, furnished evidence in support of 
the conclusion that the organic impurities contained in gun-cotton constitute the primary 
cause of its susceptibility to change under the influence of heat and light. 
Experiment 148. — Specimens of gun-cotton were exposed in flasks to 90° and 100° 
until decomposition was established to such an extent that the vessels were filled, with 
deep-coloured vapours; a small quantity of calcic or magnesian carbonate was then 
introduced into the flask, or the gun-cotton was removed from the vessel, dusted over 
with a carbonate, and immediately replaced. Decomposition was at once arrested by 
these means ; moreover, the gun-cotton no longer exhibited any susceptibility of decom- 
position even if exposed to 90° and 100° for several successive days. 
Experiment 149. — About 5 grms. of ordinary gun-cotton were dusted over with finely 
pulverized potassic bicarbonate^ and exposed to about 95° in a long-necked flask, side by 
side with a corresponding quantity of the same specimen of gun-cotton in its ordinary con- 
dition. The “alkalized” gun-cotton gradually darkened upon the second day’s exposure, 
eventually assuming a brown colour. After exposure to the above temperature during 
five days for seven hours daily, the unprepared gun-cotton began to evolve nitrous vapours 
abundantly. The examination of a small specimen showed that the sample had under- 
gone very little change, the solubility in ether and alcohol having slightly increased. 
It was now removed from the flask, dusted over with the powdered carbonate, and 
immediately re-exposed to heat. All decomposition ceased, the gun-cotton behaving 
exactly like the specimen which was originally alkalized, except that the usual darken- 
ing took place very slowly indeed. When it had been maintained at 95°— 100°, seven 
hours daily for eight days, it was still alkaline ; after treatment with water, it exhibited 
all the original properties of the gun-cotton ; the solubility in ether and alcohol had 
undergone no increase since the alkaline salt was applied J. 
The other specimen to which the carbonate had been applied in the first instance, was 
examined after exposure to 95° for seven days. The aqueous extract had a brownish 
colour, and reduced cupric salt to a very slight extent. The extracted gun-cotton was 
perfectly white ; the strength of fibre, explosiveness, and solubility in ether and alcohol 
had undergone no change. It was now dried and again exposed in a clean flask to 95°- 
* The analysis of a specimen of soluble gun-cotton into which the ordinary material had been entirely con- 
verted by the gradual action of heat, has furnished results which appear to indicate that trinitrocellulose may 
become soluble in ether and alcohol without undergoing any modification in its ultimate composition. This 
point is now being made the subject of further investigation. 
t The object of employing this salt was to exclude any protective effect which might he exerted in the course 
of the experiment by the absorption of moisture, if a calcic, magnesian, or sodic carbonate were employed, and 
a small quantity of the corresponding nitrate were produced. 
t The exposure of this sample to 100° was afterwards continued for three weeks without any effect . — June 1867. 
