THE APPLICATIONS OF EXPLOSIVES. 



307 



ter, which becomes heated to incandescence when an electric current 

 is sent through it. This device is what is known as the naval deto- 

 nator. Mercury fulminate is so employed because it is the most vio- 



Blendino Machine for Cobdite. 



lent of all explosives in common use, and exerts a pressure of forty- 

 eight thousand atmospheres when fired in contact. Although the 

 naval detonator contains but thirty-five grains of mercury fulminate, 

 yet it will rupture stout iron and heavy tin torpedo cases when fired 

 suspended in them, it will rend thick blocks of wood when placed in 

 a hole and fired within them, and it will even pierce holes through 

 plates of the finest wrought iron one-sixteenth inch in thickness if 

 only the base of the detonator is in contact with the plate, and this 

 has been used as a test of their efficiency. Its force is markedly 

 shown by firing one in a stout iron cylinder filled with water and 

 closed tightly, when the cylinder is blown into a shredded sphere. 

 When used to detonate gun cotton, either when confined or in the 

 open, the detonator is placed in the hole which has been molded 

 in the center of the gun-cotton disk or block, so that it shall be 

 in close contact with the gun cotton. 

 I have found that perfectly dry com- 

 pressed gun cotton is detonated by 

 2.83 grains of mercury fulminate; 

 but as a torpedo attack is neces- 

 sarily in the nature of a forlorn hope 

 and should be provided with every 



possible provision against failure, and since if the detonator fails 

 the attack fails, the naval detonator is supplied with thirty-five 

 grains, so as to give a large coefficient of assurance. 



Cartridge of Cordite Siiokeless Pow- 

 der. Char^'e lor 6-inch 2 F gun, 13 

 pounds, 4 ounces. Cords, 22% inches 

 lonir, 3 inches in diameter. 



