The Chemistry of Powder and Explosives - Sciencemadness Dot Org

TRINITROBENZENE 139
According to Dautriche, 20 the density of compressed pellets of
TNB is as follows:
PRESSURE: KILOS PER SQUARE CENTIMETER
275
685
1375
2060
2750
3435
DENSITY
1.343
1.523
1.620
1.641
1.654
1.662
The greatest velocity of detonation for TNB which Dautriche
found, namely 7347 meters per second, occurred when a column
of 10 pellets, 20 mm. in diameter and weighing 8 grams each,
density 1.641 or 1.662, was exploded in a paper cartridge by
means of an initiator of 0.5 gram of mercury fulminate and 80
grams of dynamite. The greatest which he found for TNT was
7140 meters per second, 10 similar pellets, density 1.60, in a
paper cartridge exploded by means of a primer of 0.5 gram of
fulminate and 25 grams of dynamite. The maximum value for
picric acid was 7800 meters per second; a column of pellets of the
same sort, density 1.71, exploded in a copper tube 20-22 mm. in
diameter, by means of a primer of 0.5 gram of fulminate and
80 grams of dynamite. The highest velocity with picric acid in
paper cartridges was 7645 meters per second with pellets of densities
1.73 and 1.74 and the same charge of initiator.
Velocity of detonation, other things being equal, depends upon
the physical state of the explosive and upon the nature of the
envelope which contains it. For each explosive there is an optimum
density at which it shows its highest velocity of detonation.
There is also for each explosive a minimum priming charge
necessary to insure its complete detonation, and larger charges
do not cause it to explode any faster. Figures for the velocity of
detonation are of little interest unless the density is reported or
unless the explosive is cast and is accordingly of a density
which, though perhaps unknown, is easily reproducible. The
cordeau of the following table 21 was loaded with TNT which was
subsequently pulverized ih situ during the drawing down of the
lead tube:
20 Mem. poudres, 16, 28 (1911-1912).
21 Desvergnes, Mem. poudres, 19, 223 (1922).