1874.] History of Explosive Agents. 167 



masses are filled up with water, the charge being then submerged, it is 

 exploded with certainty and with results equal to those furnished under 

 similar conditions by the dry material. Provided the escape of force, by 

 transmission through the water, be retarded at the instant of the first 

 detonation, either by the resistance which the material of the case offers, 

 or by the pressure of a considerable column of water, the detonation of 

 wet gun-cotton immersed in water, and separated by thin layers of the 

 fluid from the contiguous masses, is accomplished with certainty. Results 

 fully equal to those furnished by charges enclosed in strong wrought-iron 

 cases, have been obtained by the employment of sheet-tin cases or of bags, 

 or even of simple fishing-nets, these only serving to hold the masses 

 composing the charge tightly together. If, however, the latter condition 

 is not attended to, or the depth of the immersion of the charge is insuf- 

 ficient, its detonation will not take place, even if a comparatively large 

 initiative detonator be employed. 



The suddenness and completeness with which detonation was trans- 

 mitted through small water-spaces in the experiments with wrought-iron 

 cases, led the author to attempt the application of water as a vehicle for 

 the efficient employment of only small denotating charges for bursting 

 or breaking up cast-iron shells into numerous and comparatively uniform 

 fragments (and thus to employ a hollow projectile of the most simple 

 construction to fulfil the functions of the comparatively complicated 

 " shrapnel "- or " segment "-shell). The results afforded remarkable 

 illustrations of the transmission of force by water, and may prove of 

 considerable practical importance. The destructive effects produced by 

 small detonating charges, when exploded in shells which were filled 

 up with water and entirely closed, were proportionate, not simply to the 

 amount of explosive agent used, but also to the suddenness of the con- 

 cussion imparted to the water by the explosion. Thus 7 grammes 

 (0*25 ounce) of compressed gun-cotton, detonated in a shell filled with 

 water, broke it up into nearly eight times the number of fragments 

 obtained by exploding a shell of the same kind full of gunpowder (viz. 

 containing 367*9 grammes = 13 ounces). When picric powder, which 

 is also a very violent explosive agent, though much less sudden in its 

 action, was detonated in one of these shells, in the same way as the small 

 charge of gun-cotton, 28*3 grammes (=1 ounce), or an amount four 

 times greater than that employed of the latter substance, burst the shell 

 into about the same number of fragments as were produced by the 13 

 ounces of gunpowder (instead of about 8 times the number, produced by 

 means of 0-25 ounce of gun-cotton). Other observations of interest 

 were made in the course of these shell-experiments ; they led, moreover, 

 to some cognate experiments which furnished interesting results. 



In developing detonation, in a perfectly closed and sufficiently strong 

 vessel, completely filled with water besides the detonating charge, the 

 resistance offered by the liquid at the instant of detonation may be re- 



