118 Professor Faraday on Gunpowder. 



contact with it without conveying an impulsive force ; hence all fulmi- 

 nating compounds are unfitted to act as substitutes for gunpowder. 

 They would shatter the piece instead of throwing the projectile out of 

 the barrel. This accident has occurred with gun-cotton, which ap- 

 proaches nearer to the character of a fulminating compound than 

 gunpowder, and therefore renders caution necessary in its employ- 

 ment. The Professor here showed the barrel of a gun which had 

 been completely burst and splayed open by a comparatively small 

 charge of gun-cotton, although the piece had been well proved by 

 gunpowder. The accident could only be ascribed to the suddenness 

 of explosion : it had produced serious injury to the individual. This 

 remarkable property of fulminating compounds was illustrated by 

 some experiments with the iodide of nitrogen, a body which, when 

 dry, explodes by mere contact with air or water in letting it fall. A 

 few grains were put on a plate and touched rather sharply by a 

 wooden rod. The plate was shattered. Some more of the iodide was 

 put on a plate and touched gently : the plate was not shattered, but 

 a circular and tolerably regular hole was blown through it at the 

 point of contact. A portion of the thick end of the stick used in the 

 performance of this experiment was also blown off, although the Pro- 

 fessor stated that not the slightest impulse or upward shock was per- 

 ceptible to his hand while holding the stick, the cause of this being 

 that motion is instantaneously given to those particles only which are 

 in immediate contact with the fulminating body, and they are rent by 

 mechanical force before this motion can be uniformly distributed 

 through the mass. Some plates were shown in which four and five 

 distinct holes had thus been produced by separate explosions of 

 the iodide of nitrogen without fracturing the plate. Hence, on firing 

 gunpowder between two layers of card, the upper layer was raised. 

 On discharging the iodide of nitrogen in the same way, no motion 

 was given to the card, but a hole was blown completely through it. 

 —Ibid. 



