1870. J on Recent Detonating Agents. 71 



detonated when closely surrouudcd by the substance. But in order 

 to attain this result, the cellulose-product must be presented to tho 

 detonating agent in a mechanical condition favourable to its action. 



Gun-cotton in a loose flocculent condition, or even if in tho more 

 compact form of a spun yarn or thread, cannot be detonated through 

 the agency of a large charge of fulminate buried in the material. 

 The light and loose gun-cotton is simply scattered with violence ; 

 portions are sometimes inflamed by tho heat developed where tho 

 fulminate is detonated, a result which is obtained with greater cer- 

 tainty the less violent the detonation produced by the fulminate- 

 charge. If, however, the gun-cotton be converted into a compact 

 form, either by ramming the wool or thread very tightly into a case, 

 or better still, by reducing the gun-cotton fibre to a very fine state of 

 division, and compressing it, when in that condition, into compact 

 masses, it becomes susceptible of detonation by the initiative action 

 of mercuric fulminate, and the quantity of the latter required to bring 

 about detonation is small (down to the limit which has been named 

 above) in proportion as the compactness or density of the compressed 

 material is increased. 



Detonation, when established in compressed gun-cotton, is trans- 

 mitted with great velocity throughout the mass, as already stated, or 

 from one to another of contiguous masses, laid out in long rows, and 

 even, though at a reduced rate, if small spaces exist between the indi- 

 vidual masses. But, if a small mass of compressed gun-cotton freely 

 exposed to air be detonated when in immediate contact with gun-cotton 

 wool or loosely twisted yarn, the detonation will not be transmitted to 

 these, but they will merely be scattered and perhaps inflamed. 



The difference in the behaviour of nitro-glycerine and of gun- 

 cotton when presented to the action of a so-called initiative detonation 

 under the different conditions spoken of above, admits of ready 

 explanation. 



It was established, in the first instance, that the action of an 

 initiative detonation is not ascribable to the heat developed within the 

 denoting material itself, in undergoing chemical metamorphosis. If 

 it were so, the detonating mixture known as percussion cap com- 

 position and other explosive mixtures, the detonation of which is 

 attended by much greater development of heat than is obtained by 

 the action of pure mercuric fulminate, should detonate gun-cutton 

 more readily than the latter does, whereas very much larger quan- 

 tities of such materials are required to attain that result ; moreover, 

 the readiness with which gun-cotton is detonated should be solely pro- 

 portionate to the amount of fulminate used, which has been shown not 

 to be the case ; and gun-cotton should be more readily detonated 

 when in the loose and open condition than in the highly compressed 

 or compact form, because the latter presents it in the condition least 

 favourable, and the former in that most favourable, to ready and rapid 

 transformation by heat. Again, the actual temperature required for 

 the explosion of nitro-glycerine is very considerably above the 



