274 
IMPROVEMENTS IN GUN-COTTON. 
explosion of gun-cotton upon those exposed to its action. It has been stated that both 
nitrous fumes and prussic acid are among these gases, and that the one would corrode the 
gun and the other poison the artilleryman. Now, though it is true that from some kinds 
of gun-cotton, or by some methods of decomposition, one or both of these gases may be 
produced, the results of the explosion of the Austrian gun-cotton without access of air 
are found by Karolys to contain neither of them, but to consist of nitrogen, carbonic 
d'cid, carbonic oxide, water, and a little hydrogen and light carburetted hydrogen. These 
are comparatively innocuous; and it is distinctly in evidence that, practically, the gun 
is less injured by repeated charges of gun-cotton than of gunpowder, and that the men 
in casemates suffer less from its fumes. It seems a disadvantage of this material as com¬ 
pared with gunpowder that it explodes at a temperature of 277° Fahr.; but against the 
greater liability to accidents from this cause may be set the almost impossibility of ex¬ 
plosion during the process of manufacture, since the gun-cotton is always immersed in 
liquid, except in the final drying.* Again, if it should be considered advisable at any 
time it may be stored in water, and only dried in small quantities as required for use. 
The fact that gun-cotton is not injured by damp like gunpowder is, indeed, one of its 
recommendations, while a still more important chemical advantage which it possesses 
arises from its being perfectly resolved into gases on explosion ; so that there is no 
smoke to obscure the sight of the soldier who is firing or to point out his position to the 
enemy, and no residuum left in the gun, to be got rid of before another charge can be 
introduced. 
Mr. J. Scott Eussell read the Eeport on the mechanical portion of this question, 
by which it appears that the greater effects are produced by gases generated from 
gun-cotton than by gases generated from gunpowder, and it was only after long 
and careful examination that the Committee were able to reconcile this fact with 
the low temperature at which the mechanical force is obtained. The great waste 
of force in gunpowder constitutes an important difference between it and gun¬ 
cotton, in which there is no waste. The waste in gunpowder is 68 per cent, of 
its own weight, and only 32 per cent, is useful. This 68 per cent, is not only waste 
in itself, but it wastes the power of the remaining 32 per cent. It wastes it mecha¬ 
nically, by using up a large portion of the mechanical force of the useful gases. The 
waste of gunpowder issues from the gun with much higher velocity than the projectile; 
and if it be remembered that in 1001b. of useful gunpowder this is 68 lb., it will appear 
that 32 lb. of useful gunpowder gas is wasted in impelling a 68-lb. shot composed of the 
refuse of gunpowder itself. There is yet another peculiar feature of gun-cotton. It can 
be exploded in any quantity instantaneously. This was once considered its great fault; 
but it w r as only a fault when we were ignorant of the means to make that velocity any¬ 
thing we pleased. General von Lenk has discovered the means of giving gun-cotton any 
velocity of explosion that is required by merely the mechanical arrangements under 
which it is used. Gun-cotton in his hands has any speed of explosion, from 1 foot per 
second to one foot in a second, or to instautaneity. This instantaneous ex¬ 
plosion of a large quantity of gun-colton is made use of when it is required to produce 
destructive effects on the surrounding material. The slow combustion is made use of 
when it is required to produce manageable power, as in the case of gunnery. It is plain, 
therefore, that if we can explode a large mass instantaneously we get out of the gases 
so exploded the greatest possible power, because all the gas is generated before motion 
commences, and this is the condition of maximum effect. It is found that the condition 
necessary to produce instantaneous and complete explosion is the absolute perfection of 
closeness of the chamber containing the gun-cotton. The reason of it is, that the first 
ignited gases must penetrate the whole mass of the cotton, and this they do, and create 
complete ignition throughout, only under pressure. This pressure need not be great. 
For example, a barrel of gun-cotton will produce little effect and very slow combustion 
when out of the barrel, but instantaneous and powerful explosion when shut up within 
it. On the other hand, if we desire gun-cotton to produce mechanical work, and 
not destruction of materials, we must provide for its slower combustion. It must 
* In ten years’ experience it is proved that this temperature is sufficiently high to ensure 
safety of manipulation; 277° Fahr. is an artificial temperature, and artificial temperatures 
accidentally produced are generally high enough to ignite gunpowder. The greater liability 
to accident from this cause can therefore, scarcely be admitted. 
