784 THE POPULAR SCIENCE MONTHLY. 



these tests tend to show that it possesses in a high degree the elements 

 desired in the ideal high explosive for military purposes, if not for 

 commercial use. 



So much difficulty was encountered in the first attempts at the con- 

 struction of a suitable primer for its explosion, that it seemed doubt- 

 ful whether it would ever be a practicable material, as it was thought 

 that nitro-glycerine must be used to accomplish the desired result. 

 Subsequent experiments conducted in this country have shown, how- 

 ever, that a dry gun-cotton fuse with a fulminate cap containing 

 twenty-five grains will fire the gelatine with ease and certainty, even 

 when unconfined. The problem so long confronting the manufacturer 

 of explosives would seem to be nearly solved : the requisites of great 

 power in small compass, of permanency when subjected to tropical 

 heat, of ease of firing when but slightly confined, of safety from the 

 explosion of neighboring masses of the same or on being struck by a 

 projectile, and of not being affected injuriously by water, all seem to 

 be fulfilled by this agent in a manner more complete than by any 

 other. 



If it should be found that a long-continued exposure to heat tends 

 to produce decomposition, as may prove to be the case, greater care 

 in the preparation of the materials from which it is manufactured will 

 probably overcome this difficulty, and it will then bid fair to super- 

 sede gun-cotton for very many purposes, if it does not altogether take 

 its place. 



Constant allusion has been made to the use of fulminate of mer- 

 cury as an agent for the firing of other explosives. It is prepared by 

 dissolving mercury in nitric acid, and then mixing this solution with 

 alcohol, in a vessel placed in a hot-water bath. Dense white fumes 

 soon arise from the agitated liquid, until finally, the disturbance hav- 

 ing subsided, the bottom of the vessel is found covered with a gray 

 powder, which is afterward thoroughly washed. This gray powder is 

 the fulminate used in the caps and cartridges familiar to sportsmen, 

 as well as in the primers for cannon and the fuses for the explo- 

 sion of a quantity of gunpowder or other explosives. Being harmless 

 when wet, it is usually kept and handled in that condition. Generally 

 speaking, electricity is the agent by means of which the fulminate is 

 ignited ; the fuse for this purpose is ordinarily constructed as follows : 

 A brass or copper cylinder, about half an inch in diameter, closed at 

 one end, is partially filled with the desired quantity of the wet fulmi- 

 nate ; when this has become thoroughly dry, a wooden plug closing the 

 entrance is inserted ; in this plug are two holes, through each of which 

 passes an insulated copper wire with bared ends, which project a 

 short distance above the surface of the plug and are connected by a 

 very small wire composed of an alloy of platinum and silver ; around 

 this wire, or bridge, as it is called, is twisted a small wisp of dry gun- 

 cotton, which, when the plug is in place, comes in contact with the ful- 



