ON THE STABILITY OF GUN-COTTON. 
387 
The influence of heat upon gun-cotton furnishes an important subject for investi¬ 
gation as bearing upon the question of its use and transport in tropical climates. The 
exploding-point of gun-cotton, when in a condition most favourable to rapid heating, 
has been ascertained to lie in the neighbourhood of 150° C. (302° Fahr.). Its prolonged 
exposure to temperatures considerably exceeding those which are experienced in the 
tropics affects the stability of gun-cotton in a degree very trifling in comparison with the 
results recently published by Continental observers; and it may be so perfectly counter¬ 
acted by very simple means that the storage and transport of gun-cotton presents no 
greater danger, and is, under some circumstances, attended with much less risk of acci¬ 
dent than is the case with gunpowder. Perfectly pure gun-cotton or trinitro-cellulose 
resists to a remarkable extent the destructive effects of temperatures even approaching 
100° C. (212° Fahr.) ; and the lower nifro-products of cellulose are at any rate not more 
prone to alteration when pure. But all ordinary products of manufacture contain small 
proportions of organic nitrogenized impurities, of comparatively unstable properties, 
which have been formed by the action of nitric acid upon foreign matters retained by 
the cotton fibre, and which are not completely separated by the ordinary or even a more 
searching process of purification. It is the presence of this class of impurity in gun¬ 
cotton which first gives rise to the development of free acid, when the substance is ex¬ 
posed to the action of heat; and it is the acid thus generated which eventually exerts 
a destructive action upon the cellulose products, and thus establishes decomposition, 
which heat materially accelerates. If the small quantity of acid thus developed be 
neutralized as it becomes nascent, no injurious action upon the gun-cotton results, and 
the great promoting cause of the decomposition by heat is removed. 
The “ silicating” process prescribed by Yon Lenk was found to exert some amount of 
protective influence upon gun-cotton when exposed to heat; this result is, however, not 
due, as supposed by him, to the closing up of the fibre by an insoluble silicate, but 
simply to the deposition of a small quantity of earthy (and possibly of alkaline) carbo¬ 
nate upon the fibre when the silicate undergoes decomposition during the drying and 
subsequent washing process. The amount of protection thus afforded to the gun-cotton 
by the presence of a substance capable of neutralizing acid is in this case as liable to 
-variation as that resulting from the deposition of carbonates of lime and magnesia upon 
the material during the long-continued immersion in flowing water. 
The same result is readily and more uniformly attained by distributing through the 
gun-cotton a small proportion of carbonate of soda, applied in the form of solution. 
The introduction into the finished cotton of one per cent, of carbonate of soda affords 
to the material the power of resisting any serious change even when exposed to such 
elevated temperatures as would induce some decomposition in the perfectly pure cellulose 
products. The only influences which the addition of that amount of carbonate to gun¬ 
cotton might exert upon its properties as an explosive, would consist in a trifling addition 
to the small amount of smoke attending its combustion, and in a slight retardation of its 
explosion, neither of which could be regarded as results detrimental to the probable 
value of the material. 
Water acts as a most perfect protective to gun-cotton (except when it is exposed to 
sunlight) even under extremely severe conditions of exposure to heat. Actual immersion 
in water is not necessary for the most complete preservation of gun-cotton ; the material, 
if only damp to the touch, sustains not the slightest change, even if closely packed in 
large quantities. If as much water as possible be expelled from wet gun-cotton by the 
centrifugal extractor, it is obtained in a condition in which, though only damp to the 
touch, it is perfectly non-explosive ; the water thus left in the material is sufficient not 
only to act as a protective against change, but also to guard against all risk of accident. 
It is, therefore, in this condition that all reserve stores of the substance should be pre¬ 
served, or that it should be transported in large quantities. 
It is confidently believed that the results which have been described amply demon¬ 
strate that the objections which have been of late revived, especially in France, against 
the employment of gun-cotton, on the ground of its instability, apply only in a com¬ 
paratively slight degree to the material produced by strictly pursuing the system per¬ 
fected by Von Lenk ; that, as far as they do exist, they have been definitely traced to 
certain difficulties in the manufacture of pure gun-cotton which further experimental 
research may overcome ; but that, in the meantime, these objections are entirely set 
aside by the adoption of two very simple measures, against the employment of which no 
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