3o8 



POPULAR SCIENCE MONTHLY. 



GUX-COTTOX Si'AK TOKPEDO. 



A characteristic feature of gun cotton is that it may be deto- 

 nated even when completely saturated with and immersed in wa- 

 ter, if only some dry gun cotton be deto- 

 nated in contact with it. Thus in one 

 experiment a disk of dry gun cotton was 

 covered with a water-proof coating and 

 the detonator inserted in the detonator 

 liole of this disk. This dry disk was laid 

 upon four uncoated disks, the five lashed 

 tightly together, and sunk in Newport 

 Harbor, where the column remained 

 until the uncoated disks were saturated 

 with salt water, when the mine was fired 

 and the saturated disks were found by 

 measurement of the work done to have 

 been completely exploded. I have found 

 that three ounces of dry compressed 

 gun cotton v/ill cause the detonation 

 of wet compressed gun cotton in contact with it, but forty 

 ounces of dry gun cotton are used as the primer in our naval 

 mines and torpedoes, so as to give a large coefficient of assur- 

 ance. 



In the mining and other industries the fulminate is used in 

 smaller quantities and it is generally mixed with potassium chlo- 

 rate, the mixture being com- 

 pressed in small copper cases 

 and sold as blasting caps. 

 They are fired by means of a 

 piece of Bickford or running- 

 fuse, consisting of a woven 

 cotton or hemp tube contain- 

 ing a core of gunpowder, 

 which is inserted in the mouth 

 of the copper cap and made 

 fast within it by crimping. 

 The capped fuse is then in- 

 serted in a dynamite cartridge 

 so that the cap is firmly in 

 contact with the dynamite, 

 the mouth of the cartridge 

 is fastened securely, and the 

 charge inserted in the bore- 

 hole in the rock and tamped, 

 lighted, and the fire travels at the rate of three feet per minute 



lil,il\VI.\(} II' TIIK SCIIOONEK .Joil.l'll JIkN1:V. 



The protruding end of the fuse is 



