THE HISTORY OE EXPLOSIVE AGENTS. 
363 
mixture ; hence when the initiative detonator is surrounded by such a mass it is in 
contact at all points with some portion of the nitroglycerine, and the latter is in con- 
tinuous connexion throughout ; detonation is consequently as readily established and 
transmitted through the mass as though it consisted entirely of nitroglycerine. 
The case is different when a solid explosive compound is diluted with solid inert 
material. In an intimate mixture of the finely divided substances there must obviously 
be complete separation of the particles of the explosive at a number of points propor- 
tionate to the extent of dilution and to the state of division ; a condition of things may 
therefore arise, within comparatively narrow limits, when the establishment or trans- 
mission of detonation is impeded, either by a diminution of the extent of contact between 
the exploding substance itself and the initiative detonator, or by the barrier which the 
interposed non-explosive particles oppose to the transmission of detonation, or by both 
causes. In some experiments made with intimate mixtures of mercuric fulminate and 
French chalk (selected for the purpose as being a bulky material), it was found im- 
possible to detonate mixtures containing more than one fifth part by weight of the 
diluent by means of one grain (’065 grm.) of mercuric fulminate confined in a copper 
capsule and exploded in close contact with the mixtures ; that quantity, similarly con- 
fined, sufficed to detonate undiluted fulminate through a tube 8 inches ( - 2 m.) long 
and 0 - 5 inch ('013 m.) in diameter. A mixture of four parts of fulminate and 
one of French chalk was exploded, without destructive effect, by the grain of confined 
fulminate fired in contact with it ; when the diluent was reduced to one eleventh, the 
mixture detonated under these conditions, and it was also found to be detonated through 
a pewter tube 8 inches ('2 m.) long, like the undiluted fulminate. In this mixture 
the fulminate particles were no longer sufficiently separated to effect their ready deto" 
nation. 
If an intimate mixture of finely divided particles of sensitive solid explosive compound 
and an inert solid diluent be compressed into compact masses, the mixture is consider- 
ably more susceptible of detonation than if it were in the loose condition ; in this respect 
it resembles the undiluted material ; indeed, so far as has been ascertained by experi- 
ments with gun-cotton, dilution may under these conditions be carried to a considerable 
extent, with little reduction in the sensitiveness of the material to detonation, provided 
the diluent consists partly or entirely of a soluble salt, as will be presently shown. 
Intimate mixtures of finely divided gun-cotton with solid oxidizing agents , converted 
into compact and very homogeneous masses by compression while wet and subsequent 
desiccation, furnished interesting results when compared with pure compressed gun- 
cotton in regard to their susceptibility to detonation. Pure trinitrocellulose requires 
for the complete oxidation of its carbon the provision of 24 - 24 of oxygen for every 
hundred parts, in addition to that which its composition includes. This proportion of 
oxygen would be furnished by the admixture with that compound of 61-2 parts of 
potassium nitrate, 51’5 parts of sodium nitrate, or 61*8 parts of potassium chlorate. 
Gun-cotton, when prepared with the greatest care upon a manufacturing scale according 
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