1879. J on Uecent Detonating Agents. 69 



of 3 inches between the two substances. But on attempting to apply 

 nitro-glyceriue to the detonation of gun-cotton, the quantity of the 

 former, which was detonated in close contact with compressed gun- 

 cotton, was gradually increased in the first instance to ^ oz. and sub- 

 sequently even to 2 oz. without accomplishing the detonation of the 

 latter, which was simply dispersed in a fine state of division, in all 

 instances but one in a large number of experiments. 



The force developed by the detonation of nitro-glycerine was 

 found, by careful comparison of the relative destructive cflfects of 

 corresponding quantities, to be decidedly greater than that of the 

 fulminate, of wliich from 2 to 5 grains suffice for developing the 

 detonation of gun-cotton, when it is in close contact with them. The 

 non-susceptibility of gun-cotton to detonation by nitro-glycerine is 

 therefore, it need scarcely be said, not ascribable to any deficiency in 

 mechanical force suddenly applied when the nitro-glycerine is deto- 

 nated. 



That the power possessed by different very highly explosive sub- 

 stances, of inducing tlie detonation of such bodies as gun-cotton and 

 nitro-glycerine, is not solely ascribable to the operation of mechanical 

 force very suddenly developed, is indicated not only by the singular 

 inertness of gun-cotton to the influence of nitro-glycerine as a deto- 

 nating agent, but also by a comparison of the behaviour of other 

 detonating substances with that of the mercuric fulminate, when applied 

 to the detonation of gun-cotton. Thus the detonation of silver ful- 

 minate is very decidedly sharper than that of the mercury compound, 

 yet it is in no way superior to the latter in its power as an initiative 

 detonating agent ; indeed, a somewhat larger amount of it appeared to 

 be required than of the mercury salt to induce detonation of gun- 

 cotton with certainty. Again, the iodide and chloride of nitrogen 

 are far more susceptible of sudden detonation than the silver fulminate ; 

 yet while 5 grains of the latter, confined in a stout metal envelope, 

 suffice to detonate gun-cotton, 50 grains of chloride of nitrogen 

 confined by water, appeared to be the minimum amount with which 

 the detonation of gun-cotton could be accomplished with certainty, 

 while no success attended the employment of confined iodide of nitro- 

 gen in quantities ranging up to 100 grains. 



The incompatibility of these results with the general conclusion, 

 based upon numerous and greatly varied experiments, that the facility 

 with which the detonation of gun-cotton and nitro-glycerine, and 

 bodies of a similar character as explosives, is induced by an initiative 

 detonation, is proportionate to the mechanical force aided by the heat 

 developed by the latter, led the lecturer to the conclusion that a 

 synchronism or similarity in character or quality of the vibrations 

 developed by the detonation of particular substances, operates in 

 favouring the detonation of one such substance by the initiative deto* 

 nation of a small quantity of another, while in the absence of such 

 synchronism, a much more powerful detonation, or the application of 



