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Modern Explosives

THE old explosive gunpowder, which was about the only one known to our forefathers, has in modern times been superseded to a great extent by others of a far more formidable character, although for various reasons it still holds its own in the service of guns both small and great. The most important of the new destructive compounds, is gun-cotton, which is made by immersing ordinary cotton-wool in a mixture of nitric and sulphuric acids. It is afterwards carefully washed to free it from any traces of acid, and then forms a substance which to all outward appearance is still cotton-wool, but which really has acquired very different qualities. Gun-cotton is generally compressed into slabs or blocks of different sizes, and in that state has the appearance of white chalk. It can be immersed in water for any length of time without losing its explosive power, and in this state it is often kept for a long time with perfect safety. Lighted by a flame it will burn away quite harmlessly, if not confined. But if it be ignited by means of a detonating fuse, its destructive power is so great that it will indent or break an iron plate upon which it is exploded.

Another terrible explosive by which many lamentable accidents have in recent years been caused, is nitro-glycerine, which, like gun cotton, is made with nitric and sulphuric acids. The glycerine is added to this mixture, and forms with it a yellow oily liquid, which is nitro-glycerine. At ordinary temperatures it is pretty safe, but in cold weather it freezes into a crystalline condition, and in this state the least movement of the vessel in which it is placed will cause it to explode with awful violence. These considerations have led to its use in a modified form. It is mixed with a porous earth, so as to present a more solid character, and in this form, under the name of dynamite, is now largely employed in mining, and also in warfare for charging torpedoes, &c.

The fulminates of the metals form another class of explosives which are most energetic in their nature, indeed some can be made of such a lively nature that the concussion of the air caused by closing a distant door is quite sufficient to set them off. Of course these extremely sensitive compounds are of no real use, and are only made in tiny quantities for the purpose of experiment. Fulminate of mercury is, however, far less liable to accidental explosion, and is much used in the manufacture of detonating fuses. It also forms the noisy part of those crackers which afford so much amusement at the supper-table. The old percussion caps also owed their explosive quality to the mixture of fulminate, nitre, and sulphide of antimony with which they were charged. These fulminates are made by dissolving a certain weight of silver, or mercury, and adding to the mixture a large quantity of alcohol, when the fulminate is formed in the shape of crystals. They are most dangerous things even in the hands of experienced persons, and amateurs should not attempt to make them.