BRITISH ASSOCIATION. 39 



•and some imperfectly ; but when the process has been thoroughly performed, he 

 finds that the gun-cotton has increased permanently about 3 per cent, in weight. 

 Much apprehension has been felt about the effect of the gases produced by the ex- 

 plosion of the 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 acid, carbonic oxide, water, and a 

 little hydrogen and light carburetted hydrogen. These are comparatively inno- 

 cuous ; 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 compared 

 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 explosion during the process of manufacture, since the gun cotton is always 

 immersed in liquid, except in the final drying. f Again, if it should be considered 

 advisable at any time, it may be stored in water, and only dried in small quanti- 

 ties 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 lo 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. 



As regards the mechanical portion of this question, it appears that greater 

 effects are produced by gases generated from gun-cotton than by gases gen- 

 erated from gunpowder, and jt was only after long and careful examination 

 that the Committee were able to reconcile this fact with the low tem- 

 perature 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 mechanically, 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 100 lb. of useful gunpowder 

 this is 68 lb., it will appear that 32 lb. of useful gunpowder gas is wasted in im- 

 pelling 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 in- 

 stantaneously. This was once considered its great fault ; but it was only a fault 

 when we were ignorant of the means to make that velocity anything we pleased. 

 General von Lenk has discovered the means of giving gun-cotton any velocity of 



+ In ten years' experience it is proved that this temperature is sufficiently high to insure 

 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. 



