EXPLOSIVE GELATINE, blasting gela tine or gum dynamite, an explosive material resembling wine jelly in appearance. It was invented by Nobel in 1878, • and consists of soluble cellulose nitrate dissolved in nitrogly cerin. Originally, the solution was effected by warming the nitroglycerin and adding the per fectly dry soluble cellulose nitrate, called nitro cotton, little by little, with stirring, whereby the nitroglycerin was made to dissolve from 4 to 10 per tent of the nitro-cotton : Then the solution was effected by the aid of a solvent like acetone, which was afterward evaporated off. All of these processes of manufacture were dangerous. In 1889, Lundholm and Sayer dis covered that if the nitroglycerin and nitro-cot ton are mixed with warm water and stirred up by compressed air, gelatinization sets in, and may be completed by pressing out the water and working the mass in malaxating machines. Explosive gelatine is a gelatinous mass, looking something like new honey in color, and vary ing in consistency from a tough leather-like material to a soft jelly, in accordance with a variety of circumstances, such as the quantity and chemical composition of the nitro-cotton used, and the methods of manufacture. In general, the thinner the gelatine, the more sen sitive it is to detonation; but, on the other hand, a thin gelatine is subject to liquefaction and possibly also to exudation, which would make it dangerous in storage, transportation and use. Specially strong detonators are re quired to explode blasting or ordinary detonators may be used with primers of dyna mite or gunpowder: In order that detonation should be transmitted through a mass of ex plosive gelatine it must be confined; for, un like dynamite, a train of it cannot be exploded in the open, except by means of an extremely powerful initial detonation. The sensitiveness of the material is still further diminished by the solution in it of camphor, or other sub stances rich in carbon and hydrogen, like ben zine or nitro-benzine. While dynamite and nitroglycerin are much less liable to be ex ploded by a blow when frozen, the reverse is true of frozen explosive gelatine. Though
while in the unfrozen condition explosive gela tine is less sensitive to shock or blows than either nitroglycerin or nitrocellulose, it is, when exploded, a more powerful explosive than either of them. This is due to the fact that when nitroglycerin is detonated, there are unused oxi dizing materials in the gaseous products; and when cellulose nitrate is detonated, there are unused combustible materials in the products. When, therefore, these bodies are mixed in the right proportions, the products will be those of complete combustion. Explosive gelatine has the advantage over dynamite in that it is prac tically unaffected by water and therefore can be stored in water. It is, on the whole, less liable to freeze than dynamite. It possesses an advantage over guncotton in being plastic and can, therefore, better adapt itself to the irregu larities of the bore-holes in loading. The spe cific gravity of explosive gelatine is from 1.5 to 1.6. If heated slowly, beginning at C., it will explode at 204° C. (399.2° F.). On rapid heating it explodes at 240° C. (464° F.). If ignited when frozen even small quantities may explode. Pure explosive gelatine is used for blasting in unusually tough rock or for blasting under water, or for military purposes. It is put up in cylindrical °sticks') in paper wrappers like dynamite. For general use in blasting it is too violent, and therefore °gelatine dynamites° are made by mixing this costly and powerful material with diluents. A great many different dopes are used, but a good example of a gela tine dynamite is agelignite,° which is made by mixing 65 per cent of explosive gelatine with 35 per cent of an explosive wood-pulp dope, giving a substance consisting of nitroglycerin 62.5 per cent, nitro-cotton 2.5 per cent, sodium nitrate 26.25 per cent, wood pulp 8.4 per cent, and sodium carbonate 0.35 per cent. "Forcite° is a similar modification of explosive gelatine containing 50 per cent of wood pulp.