76 Professor Abel [March 21, 



of gun-cotton with a nitrate or a chlorate are much less indifferent 

 to the influence of detonating nitro-glycerine than gun-cotton in its 

 jKU-e state. Chlorated and nitrated gun-cotton are detonated with 

 certainty by means of J oz. of nitro-glycerine, whereas the detonation 

 of 2 oz. of the latter accomplished the detonation of ordinary com- 

 pressed gun-cotton only once in a large number of experiments. 



If compressed gun-cotton is diluted by impregnating the mass 

 with a liquid, or with a solid which is introduced into the mass in a 

 fused state, its susceptibility of detonation is reduced to a very much 

 greater extent, than by a corresponding quantity of a solid inert body, 

 incorporated as such with the^'gun-cotton, the cause being the converse 

 of that which operates in preventing a reduction of the sensitiveness 

 to detonation of nitro-glycerine by its dilution with an inert solid. 

 In this case, the explosive liquid envelopes the solid diluent, and 

 remains continuous throughout, occupying the spaces which exist 

 between the solid particles; hence detonation is readily established 

 and transmitted. But in the case of the solid explosive, the diluent, 

 which is liquid, or at any rate is introduced into the mass in the 

 liquid state, envelopes each particle of the solid, so that a film of inert 

 material surrounds each, isolating it from its neighbours, and thus 

 opposing resistance to the transmission of detonation, which is pro- 

 portionate to the original porosity or absorbent power of the mass. 



While compressed gun-cotton, in the air-dry state, is detonated by 

 2 grains of mercuric fulminate imbedded in the material, its detonation 

 by 15 grains, applied in the same manner, becomes doubtful when it 

 contains 3 per cent, of water, over and above the 2 per cent, which 

 exists normally in the air-dry substance. Specimens which had been 

 impregnated with oil or soaked in melted fat and allowed to cool, 

 could not be detonated by means of 15 grains of fulminate. These 

 diluted samples of gun-cotton could only be detonated by adding very 

 considerably to the power of the initiative detonation ; 100 grains of 

 confined fulminate generally failed to detonate gun-cotton containing 

 from 10 to 12 per cent, of water, and if the amount reached 17 per 

 cent., 200 grains of fulminate were needed to ensure its detonation. 



But moist or wet compressed gun-cotton is decidedly more 

 susceptible of detonation by (dry) compressed gun-cotton itself than 

 by mercuric fulminate. 



Thus 100 grains of dry gun-cotton, detonated through the agency 

 of the ordinary fulminate fuze, suffice to detonate wet gun-cotton 

 containing 17 per cent, of water, though this result is somewhat un- 

 certain. If the diluting agent amounts to 20 i3er cent., detonation is 

 not certain with less than 1 oz. of dry gun-cotton, and if the com- 

 pressed material be comj^lctely saturated with water (i.e. containing 

 30 to 35 per cent.), 4 oz. of the air-dry substance, applied in close 

 contact, are needed to ensure its detonation. 



Detonation is transmitted through tubes from dry compressed gun- 

 cotton to a moist disk of the material with the same facility as to 

 the dry substance ; and this is also the case with regard to the 



