240 
MR. ABEL S RESEARCHES OH GUN-COTTON. 
reddened in spots ; the tin surface, moreover, exhibited slight signs of oxidation in some 
places where it was in very close contact with the gun-cotton*. 
The litmus in the “ silicated” and “ alkalized” gun-cotton was unaffected except, again, 
in one or two small places where it had been interposed between the gun-cotton and 
the metal surfaces. The boxes were closed immediately after inspection and examined 
eight months afterwards, when they were found quite unaltered ; the litmus paper in 
the centre of the unsilicated gun-cotton had not been at all affected, but, as before, it 
was slightly reddened when it had been in contact with the metal. 
After further preservation for eighteen months the boxes have recently been again 
inspected ; their condition is precisely what it was on the previous examination. The 
metal surfaces in the boxes containing the gun-cotton not silicated, exhibited more de- 
cided indications of oxidation where they have been in close contact with the gun-cotton 
than in the other boxes. 
Storage in a closely packed condition for nearly three years has therefore not at all 
affected the gun-cotton in these three states. The material which was not silicated has 
affected, to a slightly greater extent than the others, the metal surfaces with which it has 
been in close contact. 
Some other cases containing portions of the stock of gun-cotton, “ silicated” and not 
silicated, manufactured in the summer of 1863, and preserved since that time (Sf years) 
in a closely packed and ordinarily dry condition, have also been recently inspected, and 
their contents have been found to be as perfect as those of the cases just described. 
The cartridges enclosed in serge bags were packed and stored about 2^ years ago. 
Their condition is unaltered, and the metal cases containing them are perfectly bright. 
The cases containing a proportion of imperfectly purified gun-cotton and of soluble 
gun-cotton (Nos. 1 and 5) were packed early in January 1866. After storage for fifteen 
months their contents have been examined and found to present no points of difference 
from the other packages of gun-cotton above described, the only indications of acidity 
being discovered where the metal surfaces and the gun-cotton were in very close contact. 
Steps are now being taken to substitute simple wooden boxes, rendered impervious to 
moisture, for the metal-lined ammunition cases in which these stores of gun-cotton are 
now packed, and which have evidently, in all the experiments with large quantities of 
gun-cotton, constituted an element unfavourable to the stability of the material, the 
influence of which it is, however, important to have determined. In storing gun-cotton 
it is obviously as unnecessary as it is inadvisable to employ receptacles of metal. 
II. Exposure of large packages of gun-cotton , in different conditions , to heat. 
(a) Preliminary experiment. — A wooden box holding 4^ lbs. of gun-cotton when 
closely packed, was fitted with a gutta-percha tube intended to receive a thermometer. 
* A piece -of bright sheet tin which was packed on this occasion in the centre of the gun-cotton was exa- 
mined after a period of one year and found to have become corroded in spots, the gun-cotton having a slight 
acid reaction at the places where this effect was produced. 
