216 



Mr. Abel on the Combustion of Gun-cotton. [April 21, 



it, and a condition of things is readily attainable, under which the gun- 

 cotton-twist will simply smoulder in open air, leaving a carbonaceous 

 residue ; and the heat resulting from this most imperfect combustion will 

 be abstracted by the gases evolved more rapidly than it is generated, so 

 that in a brief space of time the gun-cotton will cease to burn at all in 

 open air*. 



The remarkable facility with which the nature of combustion of gun- 

 cotton in air or other gases may be modified, constitutes a most charac- 

 teristic peculiarity of this substance as an explosive, which is not shared 

 by gunpowder or explosive bodies of that class, and which renders it easily 

 conceivable that this material is susceptible of application to the produc- 

 tion of a comparatively great variety of mechanical effects, the nature of 

 which is determined by slight modifications in its physical condition, or by 

 what might at first sight appear very trifling variations of the conditions 

 attending its employment. 



There is little doubt that the products of decomposition of gun-cotton 

 vary almost as greatly as the phenomena which attend its exposure to heat 

 under the circumstances described in this paper. A few incidental obser- 

 vations indicative of this variation were made in the course of the experi- 

 ments. Thus, in the instances of the most imperfect metamorphosis of 

 gun-cotton, the products included a considerable proportion of a white 

 vapour, slowly dissolved by water, as also small quantities of nitrous acid 

 and a very large proportion of nitric oxide. The latter gas is invariably 

 formed on the combustion of gun-cotton in air or other gases ; but the 

 quantity produced appears always to be much greater in instances of the 

 imperfect or slow combustion of the material. The odour of the gases pro- 

 duced in combustions of that class is powerfully cyanic, and there is no diffi- 

 culty in detecting cyanogen among the products. I trust before long to 

 institute a comparative analytical examination of the products resulting 

 from the combustion of gun-cotton under various conditions ; meanwhile 

 I have already satisfied myself, by some qualitative experiments, of the 

 very great difference existing between the results of the combustion of gun- 

 cotton in open air, in partially confined spaces, and under conditions pre- 

 cisely similar to those which attend its employment for projectile or de- 

 structive purposes. I have, for example, confirmed the correctness of the 

 statement made by Karolyi in his analytical account of the products of de- 

 composition of gun-cotton, that no nitric oxide or higher oxide of nitrogen 

 is eliminated upon the explosion of gun-cotton under considerable pressure, 

 as in shells. Coupling this fact with the invariable production of nitric 

 oxide when gun-cotton is exploded in open air or partially confined spaces, 

 there appears to be very strong reason for the belief that, just as the reduc- 



* By enclosing in suitable cases solid cords, made up of two or more strands, and 

 more or less compactly twisted, I have succeeded readily in applying gun-cotton to the 

 production of fuses and slow-matches, the time of burning of which may be accurately 

 regulated. 



