458 



Proceedings of Learned Societies. 



on the contrary, can be ignited without moving the pan. In the 

 same manner a bag of gunpowder will blow open the gate of a town 

 which would not be injured by an equal weight of loose or unpacked 

 gun cotton. This appears to arise from the circumstance that gun- 

 powder after explosion leaves about 60 per cent, of solid matter, 

 which acts as a charge and produces the effect of a shot. On the 

 other hand, the products of the explosion of gun cotton are nearly 

 purely gaseous. According to Karolyi these products are — 



Carbonic Acid 



20-82 



Carbonic Oxide . 



28-95 



Nitrogen 



12-67 



Hydrogen . 



316 



Marsh Gas . 



7-24 



Water 



.25-34 



Carbon 



1-82 



The character of these products appears to account for the cir- 

 cumstance that with gun cotton there is only two-thirds the amount 

 of recoil that is produced by gunpowder in a clean gun ; for as sixteen 

 pounds of powder produce by the explosion ten pounds of solid 

 matter, which has to be sent out of the gun at a high velocity, the 

 recoil must be necessarily greater than with gun cotton of equal 

 explosive power, the products of whose combustion is entirely 

 gaseous. 



Gun cotton, when employed in artillery service, is found not to 

 heat the gun in the same manner as gunpowder does ; this is pro- 

 bably due to the fact that a large quantity of steam is formed during 

 its explosion. This renders so large an amount of heat latent that 

 the gun is not sensibly warmed. 



Unlike gunpowder, gun cotton can be wetted and dried repeatedly 

 without injury. This introduces a great element of safety in the 

 manufacture, which is carried on for the most part whilst the gun 

 cotton is damp and consequently inexplosive. 



Enclosed in a case or gun the effect of gun cotton is three times 

 greater than that of powder, one pound doing the work of three of 

 powder. Twenty-five pounds of gun cotton placed in a box at the 

 loot of a palisade formed of trees twenty inches in diameter, was 

 found to shatter three of the trees to minute splinters, and to open 

 a wide passage available for military purposes. Four hundred and 

 Jiffy pounds of gun cotton exploded in the water, twenty feet distant 

 from a vessel of 400 tons, utterly destroyed the ship, some of the 

 fragments being blown upwards of 400 feet high in the air. 



B hi ployed lor mining purposes it is found that one-twelfth the 

 weight of tlio coarse mining powder previously used is equally 

 efficient. 



In confined places, such as mines and casemates, the absence of 

 sulphurous smoke enables the workmen or soldiers to continue firing 

 any length of time without inconvenience, often a point of great 

 practical importance. 



The relative power and properties of gunpowder and gun cotton 

 may be inferred from the following table — 



