The Romance of Modern Chemistry

EXPLOSIONS AND EXPLOSIVES gun-cotton, the gun-cotton explodes with extraordinary violence. It is well known that if a violin is made to emit a particular note, the string of a second instrument in the immediate neighbourhood, if tuned to that note, will take it up and vibrate spontaneously. Some chemists have thought that something analogous to this takes place when mercury fulminate is exploded in contact with gun- cotton ; the vibrations set up by the detonator are sup- posed to excite similar vibrations in the gun-cotton, so much so that the latter undergoes what might be called a sympathetic decomposition. Whether this is the correct explanation or not, there is no doubt that gun-cotton fired by a detonator gives a much greater effect than the same material fired in the ordinary way. This increased effectiveness is due to the greater rapidity of the explosion induced by the detonator. Thus if a train of ordinary gun-cotton is touched with a hot rod the resulting combustion advances only a few feet in several seconds, whereas if a train of compressed gun-cotton is detonated by mercury fulminate it is estimated that the explosion is propagated along the train at the rate of 200 miles a minute. Perhaps still more curious and valuable was the dis- covery that wet gun-cotton, which is not explosive under ordinary conditions, could be detonated as easily as the dry material. A red-hot iron may be put into a mass of wet gun-cotton without setting it on fire; and a Govern- ment Committee, in order to demonstrate incontestably the possibility of safely storing this explosive in the moist condition, once instituted experiments in which an iron case, containing a ton of wet gun-cotton was put in a magazine and surrounded with shavings and other in- 176