THE HISTOEY OE EXPLOSIVE AGENTS. 
359 
fulminate, which was exposed to the concussion of a distant detonation transmitted 
through a tube, was frequently exploded in a manner quite distinct from the violent 
detonation developed in other instances. It has even occurred that the silver fulmi- 
nate, which under all ordinary conditions detonates violently even when only one 
particle of a mass is subjected to a sufficient disturbing influence, has been exploded 
without the usual development of force by the transmitted effect of a detonation of 
mercuric fulminate ; that is, the extremity of the glass tube into which a particular 
quantity of the silver compound has been inserted was simply broken once across, the 
paper boat in which the fulminate rested being only partly destroyed, instead of their 
being reduced to small fragments, as was usually the case with the same quantity of 
the substance. 
In all these instances the violence of the concussion transmitted was obviously only 
just bordering upon that required for the development of detonation ; and it appears 
most probable that only some small proportion of the mass of fulminate or gun-cotton 
was in a condition or position favourable to the operation of the explosive force trans- 
mitted through the tube. The remainder of the mass would then be dispersed by the 
gases developed from the detonated portion ; in some instances the particles would be 
inflamed at the moment of their dispersion, in others they would even escape ignition. 
The latter appears to be always the case when gun-cotton is exploded by a blow from a 
hammer or falling weight. However carefully the arrangements are adjusted with a 
view to distribute such a blow uniformly over the entire mass struck, the concentration 
of a preponderance of the force applied upon some portion or portions of the entire 
mass appears almost inevitable ; hence only a small proportion is actually detonated, 
the remainder being instantaneously dispersed by the gases suddenly generated while 
the weight is resting upon the support. This was well illustrated by the results of 
some very carefully conducted experiments, in which cylindrical masses of compressed 
gun-cotton, all of the same dimensions and density (1 inch diameter and 1 inch thick), 
were placed on and between two smooth brass plates upon a flat anvil, adjusted in a 
level position, and were submitted in that position to the blow of a falling weight (of 
50 lb.), the striking surface of which was properly levelled and maintained in its adjusted 
position during the descent of the weight by means of guides. The small cylinder of 
gun-cotton (which had been originally produced by submitting the pulped material to a 
pressure of four tons on the square inch) was reduced to one third its original length 
by the fall of the weight from a height of 3 feet, but no detonation was produced ; with 
a four-foot fall of the weight on another cylinder, a slight detonation was produced, 
but the principal portion of the gun-cotton was scattered ; the results were quite similar 
in further experiments, in which the height of fall of the weight was raised by incre- 
ments of 1 foot to 10 feet : the detonations were somewhat sharper when the weight 
fell from 12 feet and upwards ; but in every instance, even when the weight was allowed 
to fall from the maximum available height (39 feet), only a small proportion of the 
gun-cotton was detonated, the remainder being violently dispersed in a finely divided 
