1867.] Mr. F. A. Abel on the Stability of Gun-cotton. 419 



of the material, that the storage and transport of gun-cotton presents no 

 greater danger, and is, uuder some circumstances, attended with much less 

 risk of accident than is the case with gunpowder. 



7. Perfectly pure gun-cotton, or trinitrocellulose, resists to a remarkable 

 extent the destructive effects of prolonged exposure to temperatures even 

 approaching 100° C. ; and the lower nitro- products of cellulose (soluble 

 gun-cotton) are at any rate not more prone to alteration when pure. The 

 incomplete conversion of cotton into the most explosive products does, 

 therefore, not of necessity result in the production of a less perfectly per- 

 fectly permanent compound than that obtained by the most perfect action 

 of the acid mixture. 



8. 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 exposed 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 de- 

 composition which heat materially accelerates. If this small quantity of 

 acid developed from the impurity in question be neutralized as it becomes 

 nascent, no injurious action upon the gun-cotton results, and a great pro- 

 moting cause of the decomposition of gun-cotton by heat is removed. This 

 result is readily obtained by uniformly distributing through gun-cotton a 

 small proportion of a carbonate, — the sodic carbonate, applied in the form 

 of solution, being best adapted to this purpose*. 



9. The introduction into the finished gun-cotton of 1 per cent, of sodic 

 carbonate 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. That proportion 

 affords, therefore, security to gun-cotton against any destructive effects of 

 the highest temperatures to which it is likely to be exposed even under very 

 exceptional climatic conditions. 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. 



* The deposition of calcic and magnesian carbonates upon the fibre of gun-cotton, 

 either by its long-continued immersion in flowing spring water, or by its subjection to 

 the so-called "silicating" process adopted by von Lenk, produces a similar protective 

 effect, which, however, is necessarily very variable in its extent, as the amount of car- 

 bonate thus introduced into a mass of gun-cotton is uncertain ; moreover, as it is only 

 loosely deposited between the fibres, the proportion is liable to be diminished by any 

 manipulation to which the gun-cotton mav be subjected. 



2 N 2 



