THE HISTOEY OE EXPLOSIVE AGENTS. 
511 
obtained when the charges had been exploded, or were merely scattered, by the force of 
the detonating charge. It was found in every instance quite impossible to distinguish 
any difference in the suddenness or sharpness of the report produced when the detonating 
charge alone was exploded, and when it accomplished the simultaneous firing of neigh- 
bouring charges. 
The results obtained with nitroglycerine in attempts to detonate gun-cotton through 
its agency, appear to me to substantiate the view which has obtruded itself repeatedly on 
my mind upon consideration of many of the phenomena observed in the experiments 
detailed in this communication, namely, that a particular explosion or detonation may 
possess a power of determining at the instant of its occurrence similarly violent explo- 
sions in distinct masses of the same material, or in contiguous explosive bodies of other 
kinds, which power is independent of, or auxiliary to, the direct operation of mechanical 
force developed by that explosion ; that, as a particular musical vibration will establish 
synchronous vibrations in particular bodies while it will not affect others, and as a che- 
mical change may be wrought in a body by its interception of only particular waves of 
light, so some kinds of explosions or powerful vibratory impulses may exert a disturbing 
influence over the chemical equilibrium of certain bodies, resulting in their sudden dis- 
integration, which other explosions, though developing equal or greater mechanical 
force, are powerless to exercise. Thus the mechanical force developed by the explosion 
of 3'25 grms. (50 grains) of chloride of nitrogen far exceeds that exerted by the explo- 
sion of 0-32 grm. (5 grains) of the strongly confined fulminates, yet, in their effects upon 
gun-cotton, the substances in question are not on an equality unless employed in about 
those proportions. It appears, therefore, that it is necessary to increase greatly the 
mechanical force of the explosion to obtain the desired result with chloride of nitrogen, 
in order to compensate for the deficiency or absence of some peculiar power possessed 
by the explosion of the fulminates. Again, in the case of nitroglycerine, we have a 
body which explodes with a development of force quite as great as that of the strongly 
confined fulminates, yet the detonation of gun-cotton could not be accomplished by the 
explosion in close contact with it of a quantity of nitroglycerine more than sixty-five 
times greater than the amount of mercuric or silver-fulminate required for that purpose. 
Do not these facts appear to demonstrate the existence of a remarkable difference in the 
character of the concussions or vibrations produced by exploding the two materials 1 
I venture to offer the following as being the most satisfactory explanation which 
occurs to me of the remarkable differences just pointed out in the behaviour of different 
explosive agents. The vibrations produced by a particular explosion, if synchronous 
with those which would result from the explosion of a neighbouring substance which is 
in a state of high chemical tension, will, by their tendency to develope those vibrations, 
either determine the explosion of that substance, or at any rate greatly aid the disturb- 
ing effect of mechanical force suddenly applied, while, in the case of another explosion 
which produces vibrations of different character, the mechanical force applied by its 
agency has to operate with little or no aid ; greater force or a more powerful detonation 
