THE HISTOEY OF EXPLOSIVE AGENTS. 
509 
nical force exerted by the initiative detonation to which it is subjected. The force ex- 
erted by small quantities of strongly confined silver- and mercuric fulminate greatly ex- 
ceeds that developed by the explosion of comparatively large proportions of the iodide 
and chloride of nitrogen. This may be accepted as accounting, to some extent, for the 
fact that the detonation of gun-cotton could not be accomplished by an amount of iodide 
of nitrogen twenty times greater than that of fulminates required for the purpose, while 
ten times the quantity of the confined chloride were required to produce the result. 
That the quantity of mercuric fulminate required to produce detonation is reduced in 
proportion as means are applied to increase the violence of the force exerted by it at 
one time, is quite in accordance with the above view. 
Several curious and apparently anomalous effects were, however, observed in the course 
of the numerous experiments referred to in this paper, which suggest the inquiry 
whether there may not be some peculiarity in the concussion or powerful vibration pro- 
duced by a particular kind of explosion, which acts apart or distinct from the mechanical 
force of that explosion in developing or promoting the detonation or sudden chemical 
disintegration of the molecules of a neighbouring explosive body. 
The results of a few experiments instituted with nitroglycerine appear to furnish a 
decided affirmative reply to that inquiry. A comparison was in the first instance insti- 
tuted between the mechanical action of the explosion of nitroglycerine, and of the other 
materials which have been discussed. The charges of nitroglycerine were introduced 
into small wide tin tubes, freely open at the upper end or closed by means of a cement, 
and their explosion was accomplished by the detonation of a small percussion-cap, just 
immersed in or resting upon the liquid, and containing 0'07 grm. (1 grain) of mercuric 
fulminate. Nitroglycerine thus detonated produced a destructive effect upon the copper 
support very greatly exceeding that obtained with the same amount of unconfined silver- 
fulminate. As the mechanical force developed by nitroglycerine was so very consider- 
able, and as, moreover, the character of its detonation might be expected to bear some 
analogy to that of gun-cotton, it was considered probable that the latter might prove 
susceptible of detonation by a much smaller proportion of nitroglycerine than it is neces- 
sary to employ of the confined fulminates. No success, however, attended repeated 
attempts to explode gun-cotton by the detonation of 0 - 07 grm. (1 grain) and increasing 
charges up to 0‘65 grm. (10 grains) of nitroglycerine. At the same time these results 
were not quite conclusive, as it was not found easy to ensure the complete detonation of 
the liquid by the small fulminate-charge, on account of the difficulty of securing a 
favourable adjustment of the detonating cap and the very small quantity (from two to 
ten drops) of nitroglycerine used. The experiments were therefore repeated with corre- 
sponding quantities of the liquid converted into a thick paste by admixture with sand, 
in tin tubes similar to those previously used. The explosion of the nitroglycerine ap- 
peared to be rendered more certain by this contrivance, but in order more thoroughly to 
ensure its proper detonation, the charge of mercuric fulminate used for that purpose was 
increased to 0T4 grm. (2 grains). Still the detonation of gun-cotton could not be ac- 
