CHEMICAL HISTORY AND APPLIANCES OF GUN-COTTON. 
81 
only induces slow combustion in the compact gun-cotton yarn, a thick rod of iron, heated 
only to dull redness, will invariably inflame it in the ordinary manner. A piece of open yam 
cannot be ignited so as to burn in the slow manner ; on the other hand, the more com¬ 
pactly the gun-cotton is twisted, the more superficial is the slow form of combustion 
induced in it; indeed, the gun-cotton may be rendered so compact that it will simply 
smoulder in open air, if ignited as described, leaving a considerable carbonaceous re¬ 
sidue ; and the heat resulting from this most imperfect combustion will sometimes be 
abstracted by the escaping gases more rapidly than it is developed, so that the gun¬ 
cotton will then actually cease to burn, even in open air, after a short time. 
The remarkable facility with which the effect of heat upon gun-cotton may be mo¬ 
dified, so as even to produce results totally opposite in their characters, as exemplified 
by some of the experiments which have been described, renders it easily conceivable 
that this material may be made to produce the most varied mechanical effects, when 
applied to practical purposes ; that it may indeed be so applied as, on the one hand, to 
develope a force, very gradual in its action, which may be directed and controlled at 
least as readily as that obtained by the explosion of gunpowder, while, on the other 
hand, it may be made to exert a violence of action and a destructive effect far surpassing 
those of which gunpowder is susceptible. The results arrived at in Austria, which show 
that gun-cotton may be made to produce effects from three to eight times greater 
than those of gunpowder, cease to be surprising after a study of the chemical and phy¬ 
sical characteristics of this interesting explosive agent. 
The products obtained by the explosion of gun-cotton, and its decomposition under 
various conditions, have as yet been very imperfectly studied, but there is little doubt 
that they vary in their nature almost as greatly as the phenomena which attend the 
exposure of the material to heat under different circumstances. It is well known that, 
when gun-cotton is inflamed in the open air, there is produced (in addition to water, 
carbonic oxide, carbonic acid, and nitrogen) a considerable proportion of binoxide of 
nitrogen, so that the gaseous mixture assumes a red-brown tinge, and becomes very 
acid when it mixes with air. The products of the different forms of imperfect combus- 
it on which gun-cotton has been described as susceptible of undergoing, are undoubtedly 
much more complex in their character than those just referred to. They include at 
times a proportion of some substances, not yet examined, which make their appearance 
as a white vapour or smoke; cyanogen can readily be detected in all the products of 
imperfect combustion; the proportion of binoxide of nitrogen is generally so large that 
the gaseous product becomes very highly coloured when mixed with air; peroxide of 
nitrogen has also been observed in some instances ; lastly, there is little doubt that the 
products occasionally include a proportion of oxidizing gases. 
The products Avhich have just been alluded to are the results of the decomposition of 
gun-cotton either at ordinary or diminished atmospheric pressures; when the explosion 
of the material is effected in a confined space, in such a manner that the main decompo¬ 
sition takes place under pressure, the metamorphosis which the material undergoes is of 
a more simple and complete character. 
It has been found by Karolyi that when gun-cotton is exploded by voltaic agency in 
a shell which is burst by the explosion, and which is enclosed within an exhausted 
chamber, so that the products of decomposition are collected without danger, the 
results obtained under these conditions are comparatively simple; the analysis of the 
contents of the chamber, after the explosion, showed that they consisted of carbonic 
acid 20\S2 per cent., carbonic oxide 28’95, nitrogen 12 , G7. hydrogen 3TG, marsh gas 
7'24, water 2Ao4, and carbon 1*82. The decomposition of gun-cotton under these 
conditions (which are similar to those of its explosion when employed as a destructive 
agent) appears, therefore, not to be attended by the production of any oxide of nitrogen. 
The lecturer found, in some preliminary experiments made under the same conditions 
as those of Karolyi, that only a minute proportion of binoxide of nitrogen was pro¬ 
duced. These results, when compared with those obtained by the ignition of gun-cotton 
in open air and rarefied atmosphei'es, show that, just as the decomposition of this 
material is of a more complicated and intermediate character, in proportion as its com¬ 
bustion is rendered imperfect by diminution of pressure or other circumstances, so, con¬ 
versely, the change which it undergoes will be the more simple, and its conversion into 
gaseous products the more complete, the greater the pressure, beyond normal limits, 
under which it is exploded; that is to say, the greater the resistance offered to the 
