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MINUTES OF PKOCEEDINGS OF 
or the extremity of a piece of smouldering string, will induce the slow 
combustion in a thin and moderately compact twist; but a larger body, 
such as a thick rod of iron, heated only to dull redness, will effect the 
ignition both of the gun-cotton and of the gases evolved by the combustion 
of the first particles, so that the material will be inflamed in the ordinary 
manner. Similarly the red-hot platinum wire, or a stout rod heated to 
redness barely visible in the dark, if they are maintained in close proximity 
to the slowly burning surface of gun-cotton, will eventually cause the gases 
evolved to burst into flame. The more compact the twist of the gun-cotton, 
the more superficial is the slow form of combustion induced in 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 production 
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 observa¬ 
tions indicative of this variation were made in the course of the experiments. 
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 produced in combustions 
of that class is powerfully cyanic, and there is no difficulty 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, hi partially 
confined spaces, and under conditions precisely similar to those which attend 
its employment for projectile or destructive purposes. I have, for example, 
confirmed the correctness of the statement made by Karolyi in his analytical 
* 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 fuzes and 
slow-matches, the time of burning of which may be accurately regulated. 
