The Romance of Modern Chemistry

EXPLOSIONS AND EXPLOSIVES are forbidden hairpins, and no one is allowed to carry any article made of iron, such as knives or keys, for these by friction might give rise to a spark. Such precautions being necessary, the reader will understand that the handling and transport of nitro- glycerine by the uninitiated person is fraught with great danger. Hence before it leaves the factory it is converted into various forms which involve less risk. The commonest of the explosive materials thus based on nitro-glycerine is dynamite. Certain substances have the power of soaking up or absorbing nitro-glycerine, and one of these which has been found very satisfactory is an infusorial earth known as kieselguhr, which takes in as much as three times its weight of nitro-glycerine. The resulting product is dynamite, a material which is less violent than the parent substance, and more easily and safely handled. Indeed, it was not until the little device of employing absorbent kieselguhr was adopted that the manufacture of nitro-glycerine assumed practical and commercial importance. This may be gauged from the fact that in 1870 the world’s output of dynamite was only 11 tons, while twenty years later it had risen to 12,000 tons. Dynamite, like gun-cotton, bums without danger when loose and in small quantity, but when fired by a detona- ting fuse of mercury fulminate it explodes with extreme violence and rapidity. Indeed, it is estimated that the time occupied in the explosion of a dynamite cartridge is only uw of a second. One consequence of this is that when dynamite is used for blasting rock, the usual bore-holes may frequently be dispensed with, and the explosive may be laid on the top of the rock, covered merely with a little earth or clay. 178