ME. ABEL’S EESEAECHES ON GUN-COTTON. 
235 
obtained with the aqueous extract ; the proportion of matter extractable by ether and 
alcohol had very slightly increased. 
The sample was again moistened, and exposed to 100°, as before, for nine days ; at the 
expiration of this period it had sustained a further loss of T01 per cent. The total loss 
during the seventeen days’ treatment amounted therefore to 2'7T per cent. The condi- 
tion of the sample was now as follows : — it had darkened in a few places where in close 
contact with the glass, and possessed a faint odour, such as is always observed in gun-cotton 
which has been stored for some time in a warm locality ; its acidity had not increased, 
but a faint reaction of nitric acid was obtained in the aqueous extract after concentration 
to a small bulk. A trace of lime was also found in solution (evidently as calcic nitrate 
produced from carbonate in the sample). The proportion of matter extracted by ether 
and alcohol amounted to 4T per cent. ; in its original condition the sample contained 
2 ’3 per cent. 
Experiment 155. — 6‘5 grms. of gun-cotton were saturated with moisture and placed 
in a flask fitted with a straight narrow glass tube of considerable length, for the purpose 
of rendering the expulsion of water very gradual. After exposure to 100° six hours 
daily, for three days, the specimen was still moist. The examination of a weighed 
sample did not furnish the slightest indications of change. The same negative result 
attended the examination of a second sample after farther exposure of the gun-cotton 
to 100° for three days. The apparatus now contained but very little moisture ; after a 
renewed exposure for three hours to 100°, a very faint coloration by nitrous vapours was 
observed in the flask ; a sample was examined, but beyond a faint acidity n,o signs of 
change were detected. The heat was continued for four hours more on the same day, 
at the expiration of which the coloration in the flask was somewhat more distinct ; but 
there were no signs of nitrous vapours on the following morning. The indication of 
change in the gun-cotton was still limited to a very faint acidity. The sample was once 
more heated for six hours, during which period no trace of moisture was deposited upon 
the cool portions of the glass. Nitrous vapours appeared again in very small quantity, 
and did not increase up to the termination of the experiment ; but on the following 
morning the apparatus contained deep-coloured vapours. The gun-cotton was now 
extracted with water ; the liquid contained a small quantity of nitric acid, but did not 
reduce cupric salt. The washed gun-cotton was almost perfectly soluble in ether and 
alcohol; the insoluble portion amounted only to T25 per cent. 
Experiment 156. — 6 '5 grms. of gun-cotton in an air-dry condition were placed in a 
capacious flask (the interior surface of which had been previously moistened) fitted with 
a long narrow glass tube. A piece of litmus was suspended in the neck of the flask. 
Shortly after the gun-cotton had been first exposed to 100° the litmus gradually assumed 
a wine-red tint, and when the heating had been continued for five hours, the paper had 
become bleached. There was no other indication of change. At the expiration of the 
second day’s heating, the small quantity of water which had condensed in the neck of 
the flask exhibited an acid reaction, and the gun-cotton possessed the peculiar odour 
