THE HISTORY OF EXPLOSIVE AGENTS. 
339 
explosion of a detonating substance must be attributed to a peculiar vibratory motion, 
differing in character with the constitution and properties of the substance, and acting 
independently of the concussion and heat developed by an explosion. In a subsequent 
paper * MM. Champion and Pellet described some experiments in which they compared 
the effects produced upon a series, or scale, of sensitive flames by explosions of mercuric 
fulminate and iodide of nitrogen, the quantities of explosive substances and their dis- 
tance from the flames being varied. The explosion of the fulminate was found to affect 
certain flames in the scale, leaving others unaffected, at a distance at which a corre- 
sponding quantity of iodide of nitrogen produced no effect upon any of the flames. 
When the distance of the explosion from the flames was reduced, the iodide affected 
those which represent the highest notes in the scale, while a corresponding experiment 
with the fulminate acted upon the entire series. By increasing the quantity of iodide 
used and diminishing its distance from the flames, the whole series was eventually 
affected by the explosion of that substance. Want of success in attempts to establish a 
difference between the effects of the explosion of mercuric fulminate and nitroglycerine 
upon the series of flames was ascribed by the experimenters to the limited range of the 
series (or of the analyser of vibrations) ; but they regard their results as having demon- 
strated that a marked difference exists between the character of vibrations developed by 
the explosion of iodide of nitrogen and mercuric fulminate, and that the kinds of 
vibrations developed by a particular explosive substance are modified by an augmenta- 
tion of the quantity of material exploded, so that a definite relation should be observed 
between the susceptibility to explosion of the substance (such as gun-cotton or nitro- 
glycerine) operated upon and the quantity of explosive substance required to produce 
the initiative detonation. 
The results described by MM. Champion and Pellet have certainly demonstrated that 
different explosive agents, detonated under the same conditions, may differ importantly 
in regard to the character of vibrations which they develop ; and their experiments with 
iodide of nitrogen afford some support to the hypothesis that a particular explosive 
agent is peculiarly susceptible to the disturbing influences of the class of vibrations 
which its explosion develops most readily, if not altogether to the exclusion of others. 
The observation made by them, that iodide of nitrogen, if employed in increased quan- 
tities, will develop eventually those vibrations obtained with small quantities of mercuric 
fulminate, which are not obtained with it when it is employed under the same con- 
ditions as the fulminate, is in complete accordance with the facts pointed out by me, 
that the chloride and iodide of nitrogen will only detonate gun-cotton when employed 
in very much larger quantities than the requisite amount of fulminate. It still remains, 
however, to be demonstrated why nitroglycerine, which is so readily detonated by a 
much smaller quantity of fulminate than has to be used with gun-cotton, and is also 
susceptible of detonation by small quantities of the latter material, is incapable of 
detonating gun-cotton, even when employed in comparatively overwhelming quantities. 
* Comptes Rendus, t. lxxv. p. 712. 
2 y 2 
