EXPLOSIVES 179 



Detonator. The detonator or cap is a tube of copper 

 containing a small quantity of fulminate of mercury which 

 is exploded either by a spark of fire applied to a safety fuse 



After E. I. du Pont de Nemours & Co. 



Fig. 158. Electric fuse 



or by a wire heated by an electric current. This explosion 

 fires the enveloping charge of dynamite. Caps are sold on 

 the market in boxes of one hundred, under the name of 

 single, double, triple, or quadruple strength according to 

 the quantity of fulminate of mercury contained. The 

 appearance of the cap fired by electric current differs from 

 that fired by the safety fuse in that a pair of electric wires 

 3 feet long are attached (Fig. 158). 



Preparing the charge. If a safety fuse is to be used, 

 one end is cut square and carefully inserted into a cap. 

 It should be gently pushed straight into the cap until it 

 fits against the cap filling. Hard pressure, twisting, or 

 turning of the fuse must be avoided. The open end of the 

 cap should then be fastened to the fuse with a crimper 

 (Fig. 159), a small pincer-shaped instrument made for 

 cutting fuse and binding the end of the cap around it. With 

 a small piece of hard wood or a lead pencil, a hole should 

 be made in the center of the top end of the dynamite stick, 

 the cap to which the fuse has been attached inserted in this 

 hole nearly its full length, the 

 dynamite pressed around the out- 

 side of the cap, and the fuse tied 



tO the Stick With a String. ThiS After E. I. du Pont de Nemours &Co. 



combination of the fuse, Cap, and Fig. 159. Cap crimper and fuse 

 , • 1 r * •, 11 cutter, one handle of which will 



one stick of dynamite is generally serve to ma ke the cap opening 

 known as the primer and is ready m the sttck °f d y namtte 

 to be exploded when the outer end of the fuse is lighted. 

 If one stick of dynamite is sufficient for the charge, it can 



