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I N D U S T R I A L A N D ENGINEERING CHEMISTRY
Vol. 17, No. 2
Development and Application of Initiating Explosives’ By Bennett Grotta ATLAS POWDER Co., TAMAQUA, PA.
The importance of explosives in our industrial system becomes apparent when it is realized t h a t all the great essential industries have been dependent, a t some time or other in their development, on explosives or on other material obtained by t h e aid of explosives. With the exception of black powder, all industrial explosives require for releasing their energy t h e action of a detonator containing a suitable initiating explosive, itself capable of initiation by mere ignition. Shortly after Nobel gave to the world his idea of using nitroglycerol explosives for blasting purposes, he also found t h a t fulminate of mercury was suitable for initiating his explosives. Since t h a t time t h e history of detonators has consisted chiefly of a record of t h e efforts to produce a n initiating explosive that is superior to fulminate of mercury.
Of the various attempts to displace fulminate composition detonators, t h e efforts to produce a booster type detonator appear to have made most progress. This detonator contains a booster charge of a highly brisant nitroaromatic explosive, such as tetryl, which, in turn, is primed with a smaller charge of either fulminate of mercury or a fulminate substitute. The azides, or salts of hydronitric acid, are initiating explosives superior in initiating value to fulminate of mercury. , Recent developments indicate t h a t t h e fulminate in t h e priming charge of t h e booster detonator may be replaced, either wholly or in part, by such azides aa mercurous azide or lead azide. The superior initiating power of the booster type detonator is indicated.
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only explosive in use, could be set off by mere ignition. Nitroglycerol, however, usually burns quietly when ignited, as also do most of the dynamites now in use. After years of painstaking experimentation Nobel found, in 1864, that fulminate of mercury was admirably suited for his require ments, and to this day this compound has remained chief of initiating explosives. It is of interest to note that fulminate of mercury was discovered and first studied by Howard in 1799.*** On pouring concentrated sulfuric acid upon 50 grams of the material, an instantaneous explosion occurred which severely injured Howard and without doubt deterred him from further experimentation along this line. These are his own words: “I must confess I feel more disposed to prosecute other chemical subjects.” Except for a limited application in small arms percussion primers, fulminate of mercury was not made to serve mankind until sixty-five years after its discovery,when Nobel revealed its usefulness.
T HAS been very aptly said that high explosives form the basis of modern industry. Such a statement may come as
a shock to the chemist who is espousing the cause of one of the several alleged basic industries, other than explosives. On reflection, however, it becomes apparent that all the great essential industries of modern times have been dependent upon high explosives a t some time or other in their development. Steel would now be in its infancy but for coal, mined by the aid of explosives. So, also, would railroading. Agriculture would not yet have emerged from the stage of crude peasantry, but for the farming implements manufactured from steel, the production of which was made possible by high explosives. Modern industrial civilization depends on the utilization of some source of energy, such as coal, oil, water power, etc. When the energy must be applied with great intensity over a very short period of time, high explosives find their usefulness. Future historians, when writing on the history of our civilization, will note the sudden rise in industrialism with the application of high explosives during the last half of the nineteenth century. Broadly speaking, all explosives may be classified as primary and secondary; the former are capable of releasing their energy on the application of moderate heat or percussion, whereas the latter require sudden impulses of tremendous intensity. Ordinary black powder and also fulminate of mercury may be initiated by mere ignition, but on the other hand, TNT and any of the common dynamites require the action of a detonator to release their energy. When it is recalled that the effective performance of all high explosives is dependent upon initiating impulses s u p plied by correctly designed detonators, it becomes apparent that the detonator is the brain and nervous system of all high explosives. Thus, the true importance of the seemingly insignificant detonator is established. History of Detonators Before Nobel could give to the world his idea of using nitroglycerol for blasting purposes, he was first compelled to provide an initiator for unlocking the potential energy of his explosive. Up to that time black powder, practically the Presented before the Division of Industrial 1 Received August 25,1924. and Engineering Chemistry a t the 68th Meeting of the American Chemical Society, Ithaca, N. Y., September 8 to 13, 1924.
Properties of Fulminate of Mercury Fulminate of mercury is the mercuric salt of fulminic ncidi which has been the subject of research notably by Wohler, Liebig, and others early in the history of organic chemistry.2 It is an isomeride of cyanic acid, having a bivalent carbon. Following are the formulas of cyanic acid and isocyanic acid,. compared with that of fulminic acid: Cyanic acid: H-0-CW Isocyanic acid: H-N=C=O Fulminic acid: H-0-N=C Fulminate of mercury:
Hg
