DYNAMITE WITH NITROCELLULOSE BASE. 441 



This is in conformity with the practical tests which point to 

 the approximate equal power of 60 per cent, dynamite and the 

 mixture formed of 75 parts of ammonium nitrate, 3 parts of 

 charcoal, 4 parts of paraffin, and 18 parts of nitroglycerin. 



4. DYNAMITE WITH NITROCELLULOSE BASE. 



1. The association of nitroglycerin with gun-cotton was first 

 proposed in 1868 by Trauzl, in Austria ; but the product thus 

 obtained was dangerous and difficult to manufacture, and was 

 not adopted in practice. However, at the present day there is 

 a tendency to return to active base dynamites of a similar 

 formula (dualines). They are sometimes associated with 

 potassium nitrate (lithofracteur), etc. Mixtures containing 

 40 parts of nitroglycerin and 60 parts of gun-cotton or nitro- 

 lignite, with the addition of 2 per cent, of ammonium carbonate, 

 are those which are more especially manufactured. These 

 mixtures do not correspond to a perfect combustion, but they 

 will produce effects very closely approaching the mean of their 

 components. Dynamite with ligneous nitrocellulose base is 

 somewhat less sensitive to shock and freezing than that con- 

 taining gun-cotton. If potassium nitrate be superadded it 

 allows of the combustion being completed, but it increases the 

 sensitiveness. 



2. Some years since Nobel conceived the idea of forming a 

 compound of quite a different order by dissolving collodion 

 cotton in nitro-glycerin in the proportion of 93 parts of the 

 latter and 7 parts of the former, and in this way obtained the 

 substance called blasting gelatin, explosive gelatin, or gum 

 dynamite, a clear, yellow, gelatinous, elastic, transparent com- 

 pound, more stable than ordinary dynamite, especially from a 

 physical point of view, for it gives rise to no exudation, even by 

 pressure. It is unchangeable by water (see further on). Lastly, 

 it is much more powerful than Kieselguhr dynamite and com- 

 parable in this respect to pure nitroglycerin. 



By adding to blasting gelatin a small quantity of benzene, or, 

 better still, of camphor (from 1 to 4 per cent.), it is rendered 

 insensible to mechanical actions which cause the explosion of 

 ordinary dynamite, such as friction, the shock of a bullet at a 

 short range, etc. Its strength is appreciably diminished by this 

 mixture, but it is no longer developed except under the influence 

 of very strong charges of fulminate or of a special primer formed 

 of nitrohydrocellulose (4 parts), nitrocellulose and nitroglycerin 

 (6 parts), which itself may be ignited by a small charge of 

 fulminate. 



The work of the initial shock necessary to explode blasting 

 gelatin has been calculated at six times that which would be 

 required for ordinary dynamite, coeteris paribus, a difference 



