SflTRO-GtYCERlNEl. "^59 



piece of filter paper, and the paper struck with, a hammer on an 

 anvil, it will be shattered to pieces, the explosion being accompanied 

 by a bright flash and a loud report. If the nitro-glycerine is laid on 

 a stone and struck with a hammer, it is only exploded with great 

 difficulty. I have never succeeded in exploding nitro-glycerine by 

 contact between iron and wood, either when the nitro-glycerine is 

 laid directly on the wood, or when it is placed on a piece of paper. 

 The experiments of MM. Girard, Millot and Togt * show that nitro- 

 glycerine is exploded by a weight of 4 kils., 700 falling upon a space 

 of 2 square centimetres on an anvil, from a height of 0.25 metre, 

 which is very nearly equivalent to a weight of 10 lbs. falling from 

 a height of 10 inches. 



It is observed by Berthelott that the impact of such a weight 

 falling through such a distance, would only raise the temperature of 

 a mass of nitro-glycerine a fraction of a degree, if equally distributed, 

 but the conversion of motion into heat being too rapid to allow this 

 distribution to take place before a small portion is heated to its 

 exploding point, a large quantity of gas is suddenly produced, and 

 a second and more violent shock is dealt to the adjacent particles. 

 The force so developed is also converted into heat, and, in this way, 

 a continuous succession of changes is established through the whole 

 mass. 



If a small tube of thin metal charged with a few grains of fulminate 

 of mercury be fired by electricity or by a fuse while in contact -ndth a 

 portion of nitro-glycerine, the latter is exploded with great violence. 

 A small confined charge of gunpowder may be substituted for the 

 fulminate. This most important discoveiy we owe to a Swedish 

 Engineer, Mr. A. Nobel. Mr. E. O. Brown subsequently discovered 

 that gun cotton might be exploded in the same way, and Abel | 

 shewed that it might be applied successfully to many other explo- 

 sives. Nobel attributed this remarkable result simply to the heat 

 evolved by the explosion of the fulminate, but Abel § shewed that 

 this could not be the case, since the power that difierent bodies 

 possess of inducing this sympathetic explosion is in no way pro- 

 portional to the heat evolved in their combustion. He found that 

 difierent substances difiered greatly in their power of inducing the 



* Moniteur Scientiflque, xiii, 68-60 ; Q. J. Chem. Soc, ii, 770. 



t Comptes Rend., Ixxii, 759 ; Q. J. Chem. Soc, ii, 644. 

 } Phil. Trans., 15th April, 1869. § Loc. Cit. 



