1874.] History of Explosive Agents. 165 



duced in a precisely similar manner, but containing an inert salt, potassium 

 chloride, in place of the oxidizing agent. These were more susceptible 

 of explosion by nitroglycerine than pure gun-cotton, but decidedly less 

 so than the " nitrate " preparations. It appears, therefore, that the ex- 

 plosion of gun-cotton by the detonation of nitroglycerine is, to some extent, 

 facilitated by the greater resistance it opposes to disintegration when 

 incorporated with a salt, as described ; but that the higher susceptibility 

 to detonation by nitroglycerine of the " nitrate " (and " chlorate ") pre- 

 parations is probably chiefly due to some predisposing influence exerted 

 by the oxidizing agent. 



If gun-cotton is diluted by impregnation with a liquid, or with a body 

 solid, at ordinary temperatures, which is introduced as a liquid into the 

 mass, its sensitiveness to detonation is reduced to a far greater extent 

 than by a corresponding weight of a solid, incorporated as such, with the 

 gun-cotton. The cause of this is evidently the converse of that which 

 operates in preventing the reduction of sensitiveness of nitroglycerine by 

 its considerable dilution with an inert solid ; the liquid diluent which 

 envelopes each particle of the solid explosive material isolates it from its 

 neighbours, and thus opposes resistance to the transmission of detona- 

 tion, while with nitroglycerine the liquid explosive agent envelopes the 

 solid diluent, and thus remains continuous throughout the mass. 



The absorption of three per cent, of water by gun-cotton (in addition 

 to the two per cent, which it normally contains) rendered its detonation 

 doubtful by the " detonator " ordinarily used. Dry disks which had been 

 impregnated with oil or tallow, could not be exploded by means of one 

 gramme of mercuric fulminate, applied in a metal case in the usual way. 

 By considerably increasing the initiative charge of fulminate, damp gun- 

 cotton could, however, be detonated; and it occurred to Mr. Abel's 

 assistant, Mr. E. O. Brown, to apply the detonation of dry gun-cotton 

 itself to the development of the explosive force of the compressed material, 

 when in a moist state. 



A series of precise experiments showed that when compressed gun- 

 cotton contained as much as 17 per cent, of water, it could be detonated, 

 though not Avith absolute certainty, by 6*5 grammes (100 grains) of com- 

 pact air-dry gun-cotton exploded by means of the usual " detonator," in 

 close contact with it. When the proportion was increased to 20 per 

 cent, detonation was not accomplished with certainty by employing less 

 than 31*2 grammes (1 ounce) of the air-dry material ; and when the maxi- 

 mum amount of water (30 to 35 per cent.) was absorbed, detonation could 

 not be absolutely relied upon with the employment of less than 124-8 

 grammes (4 ounces) of air-dry gun-cotton applied in close contact. 



Moist and wet compressed gun-cotton are decidedly more readily sus- 

 ceptible of detonation by means of air-dry gun-cotton, freely exposed and 

 exploded by the usual " detonator " of mercuric fulminate, than by means 

 of the confined fulminate applied alone ; thus, when the material contained 



