THE HISTORY OE EXPLOSIVE AGENTS. 
515 
with the view of comparing the destructive power of gunpowder and gun-cotton, in which 
charges of these materials were exploded in proximity to submerged targets, with syste- 
matic variations of the strength of the cases containing the charges, the depth of their 
immersion beneath the surface, and their distances from the targets. The results of these 
experiments warranted the conclusion that gun-cotton, when confined in cases of suffi- 
cient strength to develope its full explosive action, exerted a destructive effect equal to 
about five times that of gunpowder. A few experiments to compare with these have 
been recently instituted with charges of gun-cotton enclosed in thin sheet-metal cases 
and exploded by means of detonating fuses, and in these the destructive action upon 
vertical targets, placed at very considerable distances from the charges, was from ten to 
twelve times greater than that of gunpowder. The concussion imparted through the 
water to considerable distances, by the explosion of small charges (2 to 3 lb.) of gun- 
cotton in the new manner, very greatly exceeded in their effects the results produced 
by the explosion of submerged charges by the ordinary method. 
A series of experiments has been instituted with the object of ascertaining whether 
the remarkable results obtained by exploding gun-cotton through the agency of a deto- 
nation were in any way ascribable to a peculiarity in the results of the metamorphosis. 
Known weights of gun-cotton have been exploded in vacuo by means of a small deto- 
nating fuse, and the volume of gas produced accurately determined. After deducting 
the volume furnished by the fuse employed, the results obtained corresponded very 
closely to those furnished by exploding shells, charged with gun-cotton, through the 
agency of a heated platinum-wire, under precisely similar conditions. The products of 
explosion of the detonated gun-cotton have been submitted to complete analysis, and 
the results (which will be given in detail in a memoir “ On the Results of Explosion of 
Gun-cotton ” which I hope shortly to submit to the Royal Society) did not differ in any 
very important respect from those obtained by the most complete metamorphosis of the 
substance when exploded in strong shells under ordinary conditions. As the chemical 
change sustained by the decomposition of gun-cotton, when exploded through the agency 
of a detonation, cannot be said to differ in completeness from that consequent upon a ful- 
filment of the ordinary conditions essential to the development of its full explosive force, 
the increased destructive effect developed by the explosion of gun-cotton through the 
agency of a detonation must obviously be ascribed to the greater rapidity of its explosion 
under these conditions. This conclusion appears to receive confirmation from some of 
the results of a series of practical blasting operations which I have recently conducted at 
Allenheads, in conjunction with Thomas Sopwith, M.A., F.R.S., from which it appeared 
that, while the splitting and shattering effects upon hard rock was much greater with 
“ detonated ” gun-cotton than with charges of this material exploded in the ordinary 
way, the displacement or projection of the broken rock appeared decidedly less consider- 
able*. Again, the work accomplished in the way of displacement in a comparatively soft 
and yielding material, such as a very friable rock ( e . g. chalk or soft limestone), is less 
* These results are home out by recent experiments at Portsmouth upon the demolition of fortifications. — 
November 1869. 
