282 
MR. ABEL’S RESEARCHES ON GUN-COTTON. 
100°. During six days it has not exhibited the slightest indication of decomposition ; 
no acidity has yet been developed in it, and it is still unchanged in all its properties*. 
It would appear from these experiments that a carbonate applied in the most simple 
manner to gun-cotton in which decomposition has been established, will effectually arrest 
the change ; and that if gun-cotton containing a carbonate be exposed for some time to 
heat, the latter promotes the transformation of the unstable organic impurities into 
products fixed by the base, the result being that the gun-cotton undergoes a searching 
purification from these substances, and afterwards exhibits, in consequence, remarkable 
stability under very severe conditions of exposure to heat. 
A number of experiments has been instituted on the comparative effects of exposure 
to 90° and 60° C. of samples of gun-cotton impregnated with different proportions of 
alkaline carbonates ranging from 1 to 10 per cent., the object being to ascertain whether 
the first-named proportion would suffice to afford security against the development of 
free acid in the gun-cotton, even under conditions of exposure to heat much more severe 
than could ever be met with in actual practice, or to determine what proportion might 
be necessary for that purpose. The results of these experiments showed that 1 per cent, 
of sodic carbonate, uniformly distributed through gun-cotton, produced but very little 
darkening effect upon the material, even when the latter was exposed seven hours daily 
for several weeks (three weeks and upwards) to 95° or 100°, and that no free acid was 
developed by a continuation of exposure to 95°-100° for three weeks. Gun-cotton 
containing 2 per cent, of the carbonate did not change colour to a much greater extent, 
and exhibited still a distinct alkaline reaction after exposure to 95°-100° for four weeks. 
Samples containing from 4 per cent, upwards of alkaline carbonate darkened very con- 
siderably upon long-continued exposure to heat ; and a trifling loss in weight was sus- 
tained by them, in instances when the treatment was continued between four and five 
months. This loss somewhat exceeded that which would have been simply occasioned 
by expulsion of the entire carbonic acid contained in the sodic salt, and furnished 
evidence of the escape of small proportions of volatile matter. The strength of the fibre 
was not appreciably affected even in the experiments continued for a considerable period 
at 90°-100° with the samples containing the highest proportion of carbonates. The 
colouring matter produced by the action of the alkali was entirely extracted by water ; 
and the properties of the gun-cotton were unchanged. 
It therefore appears that, although the presence of somewhat considerable proportions 
of alkaline carbonate (even as much as 10 per cent.) in gun-cotton does not exert any 
important action which can be pronounced prejudicial even under very severe conditions 
of exposure to heat, a proportion as low as 1 per cent, suffices to protect the material, 
for a longer period than ever could occur in actual practice, from the destructive action 
of such acid as may be liberated by the decomposition of the organic impurities or by 
* The exposure of this sample to 100° was continued for a total period of thirty days, after extraction of the 
carbonate, without any change resulting. A portion of the specimen was then exposed, seven hours daily for 
three days, to 115°, and it did not exhibit any symptom of change until the close of the third day . — June 1867. 
