236 
ME. ABEL’S EESEAECHES ON GUN-COTTON. 
which has repeatedly been referred to. Towards the close of the third day no trace of 
moisture was visible in the cool portion of the flask ; a very small quantity was depo- 
sited some distance up the quill-tube. Soon afterwards a faint coloration by nitrous 
vapours was observed, which had very considerably increased by the following morning. 
The gun-cotton was then found to be acid, the strength of fibre and explosiveness had 
both diminished ; the aqueous extract contained nitric acid, but not oxalic acid, nor did 
it reduce cupric salt even when highly concentrated. About three-fourths of the washed 
gun-cotton dissolved in ether and alcohol, a portion being rapidly dissolved, the re- 
mainder more slowly; the more soluble part yielded a tough collodion film*. 
The following points of interest and importance are established by the results of these 
and other similar experiments. 
(1) Gun-cotton immersed in water perfectly resists decomposition when exposed for 
long-continued periods to 100° C. ; and this severe treatment has no effect upon the ma- 
terial, even if it is only in a moist condition, or confined in an atmosphere of aqueous 
vapour. But if the moist specimens are exposed to bright daylight and sunlight for a 
considerable period, the water or aqueous vapour does not exert the same protective 
power (see experiments 2 and 4, and p. 192). 
(2) If the water or aqueous vapour is allowed to escape during exposure to 100° 
until the gun-cotton and the atmosphere surrounding it have become almost dry, decom- 
position commences very gradually; and by arresting the change at a particular period 
the material is found to be completely reduced to soluble gun-cotton, without the 
formation of any appreciable amount of the secondary products which result from the 
action of liberated acid upon the cellulose-products (see experiments 155 and 156). 
The perfect protection afforded by moisture to gun-cotton at 100° C., under severe 
conditions, rendered any experiments in this direction at somewhat lower temperatures 
unnecessary. The following experiment furnishes, however, interesting confirmation of 
the results obtained by operating at higher temperatures. 
Experiment 15 7. — 69-706 grms. of gun-cotton, in an air-dry condition, and 52*196 grms. 
of the same sample, soaked in distilled water, which was afterwards expressed as com- 
pletely as possible, were introduced into large bottles, into which the stoppers were 
loosely inserted. These were then placed in a water-oven, the temperature of which 
was continually maintained at 60°-65° day and night. At the expiration of two 
months both samples were weighed in an air-dry condition. The results indicated a 
loss of weight of 12-8 per cent, in the dry sample, and of only 0-13 per cent, in the 
other. After further exposure of the samples as before, for five weeks, the vessel con- 
taining the dry one was filled with very deep-coloured vapours, and the experiment was 
* This product was submitted to analysis. The proportion of carbon found corresponded more nearly to that 
contained in trinitrocellulose than to that required by the formula of the next lower cellulose-product (dini- 
trocellulose). It would appear as though the former had been rendered soluble in ether and alcohol, only a 
small proportion having suffered reduction. This point is still under investigation. 
