1879.] on Recent Detonating Agents. 08 



tivc effects much more considerable than couhl be accomplislied 

 through the agency of mucli larger amounts of gunpowder, applied 

 under the most favourable conditions. Whereas very strong confine- 

 ment has been essential for the complete explosion of tliese substances, 

 so long as the only known means of bringing about their explosion 

 consisted simply of the application of fire or sufiicient heat, no 

 confinement whatever is needed for the development, with certainty, of 

 a decidedly more violent explosive action than they are capable of 

 exerting when thus applied, if they are detonated by submitting some 

 small portion of the mass to the blow or concussion developed by a 

 sharp detonation, such as is produced by the ignition of a small 

 quantity of strongly confined mercuric fulminate. 



The conditions essential to the development of detonation in 

 masses of nitro-glycerine and gun-cotton, or preparations of them, and 

 the relations to and behaviour towards each other of these and other 

 explosive bodies, in their character or functions as detonating agents, 

 have been made the subject of study by the lecturer during the last 

 ten years, and some of the earlier results published by him in con- 

 nection with this subject also led to the pursuit of experimental 

 inquiries of analogous character by Champion and Pellet and others. 



Some of the chief results attained by Mr. Abel's experiments may 

 be briefly summarized. 



It was found that the susceptibility to detonation, as distinguished 

 from explosion, through the agency of an initiative detonation, is not 

 confined to gun-cotton, nitro-glycerine, and preparations containing 

 those substances, but that it is shared, though in very different 

 degrees, by all explosive compounds and mixtures. 



It was demonstrated that the detonation of nitro-glycerine and 

 other bodies, through the agency of an initiative detonation, is not 

 ascribable simply to the direct operation of the heat developed by the 

 chemical changes of the charge of detonating material, and that the 

 remarkable property possessed by the sudden explosion of small 

 quantities of certain bodies (the mercuric and silver fulminates) to 

 accomplish the detonation of nitro-glycerine and gun-cotton, is 

 accounted for satisfactorily by the mechanical force thus suddenly 

 brought to bear upon some part of the mass operated upon. Most 

 generally, therefore, the degree of facility with which the detonation 

 of a substance will develop similar change in a neighbouring explosive 

 substance, may be regarded as proportionate to the amount of force 

 developed ivithin the shortest period of time by that detonation, the 

 latter being in fact analogous in its operation to that of a blow from a 

 hammer or of the impact of a projectile. 



Thus, explosive substances which are inferior to mercuric 

 fulminate in the suddenness, and the consequent momentary violence 

 of their detonation, cannot be relied upon to effect the detonation of 

 gun -cotton, even when used in comparatively considerable quantities. 

 Percussion cap composition, for example, which is a mixture of 

 fulminate with potassium chlorate, and is therefore much less rapid 



