48 ANNUAL OP SCIENTIFIC DISCOVERT. 



gun-cotton. It seems to have a marked advantage in stability over all 

 other forms of gun-cotton that have been proposed. It has been kept 

 unaltered for fifteen years ; it does not become ignited till raised to a 

 temperature of 136 C. (277 Fahr.) ; it is but slightly hygroscopic, and 

 when exploded in a confined space, is almost entirely free from ash. 

 There is one part of the process not yet alluded to, and the value of 

 which is more open to doubt, the treatment of the gun-cotton with a 

 solution of silicate of potash commonly called water-glass. Some Aus- 

 trian chemists think lightly of it ; but Von Lenk considers that the 

 amount of silica set free on the cotton by the carbonic acid of the at- 

 mosphere is really of service in retarding the combustion. He adds, 

 that some of the gun-cotton made at the Imperial factory has not been 

 silicated at all, and some imperfectly ; but when the process has been 

 thoroughly performed, he finds that the gun-cotton has increased per- 

 manently about 3 per cent, in weight. Much apprehension has been 

 felt about the effect of the gases produced by the explosion of gun-cot- 

 ton upon those exposed to its action. It has been stated that both ni- 

 trous 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 meth- 

 ods 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 to contain neither of them, but to consist of nitrogen, car- 

 bonic acid, carbonic oxide, water, and a little hydrogen and light car- 

 buretted hydrogen. These are comparatively innocuous, and this 

 weight of evidence is, that 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 explosion during the process of manufacture, 

 since the gun-cotton is always immersed in liquid, except in the final 

 drying. 1 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 gunpow- 

 der 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. 



Physical Report. Mr. Russell stated, that greater effects are produced 

 by gases generated from gun-cotton than by gases 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 



1 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 gunpow- 

 der. The greater liability to accident from this cause can, therefore, scarcely be 

 admitted. 



