Gelatine explosive design

A recent cartridging machine is the Rollex, designed by the firm of Niepmann Sons. This operates on an entirely different principle in that the explosive is first rolled into a sheet and then portions of this sheet are cut off and automatically wrapped in paper. It can also be used for cartridging semi-gelatine explosives. 

In designing a gelatine explosive, the same questions must first be answered as in the case of all other explosives, namely, the bulk strength required and the degree of resistance to water. Again the practical requirement is to provide these properties with the minimum proportion of nitroglycerine. 

Equally severe in practice is the requirement of the break 2 test. To pass this test the explosive must have a low power when fired in an unconfined condition. The actual power has not been quantitatively measured, but is probably in the region of 15% blasting gelatine. To achieve such a result, it is necessary deliberately to design the explosive in such a way that only partial reaction occurs in the unstemmed condition. Such partial reaction can be achieved by either of two ways. 

The rock explosives used in the U.S.A. are similar in composition to those used in Europe. In addition to blackpowder (with Chilian saltpetre) dynamites with the composition tabulated below are used extensively. The oldest are the straight dynamites designated by percentage expressing the content of nitroglycerine. The latter is not gelatinized but only adsorbed by woodmeal and the like. 

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