THE TECHNOLOGIST. [Jan. 1, 1865. 



PROPERTIES AND USES OP GUN-COTTON. 261 



obscurity, delays work both in gunnery as well as in driving tunnels, 

 &c. In boring the great tunnel in Mount Cenis, Mr. Russell says that 

 the delay caused by the smoke of the powder, &c, will alone delay the 

 opening of the line for many months. The advantage of this freedom 

 from smoke in the casemates of fortresses and under the decks of men- 

 of-war during firing is obvious. Trials were made in the fortress of 

 Comara in casemates, the ventilation being intentionally obviated. 

 After fifteen rounds with gunpowder cartridge, the further sighting of 

 the gun was impossible, and on account of the injurious effect on the men, 

 it was necessary to stop firing after fifty rounds in eighty minutes. But 

 when gun-cotton was used under similar conditions, after fifty rounds 

 the men serving the gun felt no inconvenience, and the aim was visible. 

 This property of gun-cotton, coupled with the fact of less recoil as well 

 as less heating of the gun, enables a more continuous and rapid fire 

 to be carried on. One hundred rounds were fired from a six-pounder 

 in thirty-four minutes, and was raised by gun-cotton cartridges to 

 a temperature of 90° ; whilst 100 rounds of gunpowder in 100 

 minutes raised the temperature considerably above 212°, and the firing 

 with gun-cotton was continued to 180 rounds without inconvenience. 

 There is likewise another important advantage attending the use of 

 gun-cotton in artillery, especially in the case of breech-loaders. The 

 results of its decomposition are gaseous, with no solid residue, so that 

 the gun in which it is fired is left clean, without any " fouling ;" and 

 it is also now known that, exploded under pressure, as in cannon, no 

 nitrous acid is produced. From these circumstances Mr. Scott Russell 

 seems disposed to consider the action of the gun-cotton cartridge is, as 

 a propulsive agent, analogous to the steam-gun ; that it is entirely 

 resolved into highly-heated steam and gases, whilst a considerable 

 portion of the force produced by the decomposition of gunpowder into 

 gases is expended in the removal of the solid residue, amounting to 

 68 per cent. The most important question with respect to gun-cotton is, 

 whether it is stable, or, in other words, will it keep or does it undergo 

 change or spontaneous decomposition at ordinary or elevated tempera- 

 tures ? Mr. Abel brought this subject forward at the last meeting of the 

 British Association at Bath ; and after considerable experience deduced, 

 from a numerous series of experiments, that Lenk's gun-cotton was at 

 ordinary temperatures stable, and thus differed from the opposite 

 opinion which had been arrived at by the French chemists* Gun- 

 cotton is decomposed at a temperature from 120° to 212° F., and even 

 at 90° occasionally acid fumes are evolved ; but the change in its consti- 

 tution which takes place from 90° to 130° is so very slight, that it does 

 not practically affect its value, and is considered to be due to the action 

 of the acids on various foreign bodies existing in the cotton operated 



* These experiments will be found detailed in the current volume of the 

 Chemical News.' 



