Dynamite

called in the United States “giant powder,” is formed by mixing nitro-glycerine with certain porous substances, and especially with certain varieties of silica or alumina, these substances absorbing the nitro-glycerine. It was invented in 1867 by the Swedish engineer Nobel, who proposed to prevent the frequent and unexpected explosions of nitro-glycerine, at the same time without sacrificing any of its power. This he effected by the use of certain silicious earths as a base for the absorption of the nitro-glycerine, the experiment resulting in the new compound which he called dynamite, its transportation and handling being no more dangerous than that of ordinary gunpowder. It is not liable to spontaneous explosion like pure nitro-glycerine, nor can it be exploded by moderate concu ion; when unconfined, if set fire to, it will burn without explosion; it may be safely kept at any moderate temperature; is in explosive when frozen, and acts effectively under water. Its effects are proportional to the quantity of nitro-glycerine held in absorption; but under circumstances where a sustained bursting pre ure is required, not being as instantaneous in its action as nitro-glycerine, its effects are more powerful than those of an equal weight of the pure material. The best absorbent of nitro-glycerine for the formation of dynamite is a silicious earth found at Oberlohe, Hanover. During the siege of Paris, a scientific committee of investigation, engaged in experimenting on different substances as a substitute for this earth, selected as the best silica, alumina, and boghead cinders. Any of these, they declared, when combined with nitro-glycerine, formed a substance which po e ed all the remarkable qualities attributed to the dynamite of Nobel. During the siege of Paris dynamite was used succe fully by the French engineers to free a flotilla of gunboats caught in the ice on the Seine, below Char ent on, by simply placing a quantity of it on the surface of the ice. The explosion dislodged the ice for a great distance, and the ma es thus loosened, being directed into the current by the aid of a small steamer, floated down the stream, and left the river open. There are various other compounds of nitro-glycerine, such as dualin, glyoxiline, etc., all differing in the matter used as a base, they being generally some explosive substances; but none of them appears to have come into such general use or to be as reliable as dynamite. Many preparations of chlorate and picrate of pota ium have also been used from time to time as explosive agents; but their great sensibility to friction or percu ion renders them extremely dangerous; they are, therefore, not liable to come into general use. A preparation of pota ium chlorate and sulphur, not liable to explode by concu ion, but very sensitive to friction, is used with great effect as a charge for explosive bullets.