THE HISTORY OF EXPLOSIVE AGENTS. 
367 
nitroglycerine, rvhich in no instance detonated compressed gun-cotton, produced detona- 
tion of those materials in three out of four instances ; in the fourth, with nitrated gun- 
cotton, the latter was exploded, but there was no destructive effect exerted upon the 
iron plate. Results similar to the latter were always obtained when 0-75 ounce and 
0‘5 ounce of nitroglycerine were employed ; with these quantities ordinary compressed 
gun-cotton was never exploded ; the disks were simply dispersed in minute fragments. 
It appears conclusively established by these experiments that the compressed mixtures 
of gun-cotton with potassium chlorate and potassium nitrate, prepared in the manner 
described, are decidedly more sensitive to detonation by nitroglycerine than gun-cotton 
itself in a highly compressed condition. In order to ascertain whether this difference 
was ascribable to difference in structure, i. e. to the greater hardness and rigidity of the 
gun-cotton preparations containing a large proportion of saline matter, some disks were 
prepared of an intimate mixture of finely divided gun-cotton and of the inert salt 
potassium chloride ; the proportion of ingredients used corresponded to those existing 
in the “ chlorated ” and “ nitrated ” gun-cotton, and the same method of manufacture 
and extent of compression were adopted. Two ounces of nitroglycerine produced partial 
detonation of this material ; a few finely divided fragments were recovered, but the iron 
plate sustained some, though comparatively little, injury. One ounce of nitroglycerine 
exploded the chloride mixture only partially, some portions escaping ignition ; no indi- 
cation whatever of the development of detonation was obtained with the employment 
of this quantity, while in the majority of instances the “ chlorate ” and “ nitrate 
mixtures were detonated by a corresponding quantity of the liquid. 
It appears, therefore, that the ignition or explosion of the gun-cotton by the detona- 
tion of nitroglycerine is to some extent promoted or facilitated by the greater resistance 
which the material opposes to disintegration by the blow, consequent upon the in- 
creased rigidity which its incorporation with the salt imparts to it, but that the un- 
doubtedly greater susceptibility to detonation of the “nitrate” and “chlorate ” mixtures 
by nitroglycerine is chiefly due to some predisposing influence exerted by the oxidizing 
agent, arising perhaps out of the tendency to violent chemical reaction between it and 
the gun-cotton, when the conditions favourable to chemical activity are suddenly fulfilled. 
b. Dilution by inert liquids. 
If gun-cotton is diluted by impregnation with a liquid substance, or with a body solid 
at ordinary temperatures which is introduced into the mass in a liquid state, its sensi- 
tiveness to detonation is reduced to a far greater extent than by a corresponding weight 
of a solid substance incorporated as such with the gun-cotton. The obvious cause of 
this is just the converse of that which operates in preventing the reduction of sensi- 
tiveness to detonation of nitroglycerine by its considerable dilution with an inert solid. 
In the latter case, the explosive material envelopes the diluent, and occupies the spaces 
intervening between its particles ; the continuity of the explosive material is conse- 
quently preserved throughout the mixture, and detonation is therefore readily esta- 
