MUNITIONS OF PEACE. 
much to permit the explosive so resulting being used safely in confined 
or underground work, unless ventilation is very good, or plenty of time 
can be permitted to allow the poisonous vapours to dissipate. 
The efficiency of T.N.T. compared to other similar explosives is 
high. The Bureau of Mines determines relative efficiencies by com- 
paring what is termed the “unit deflective charge” and the “rate of 
detonation.” ‘The first is defined as “that weight of an explosive which 
will swing the ballistic pendulum the same distance as one half-pound 
40 per cent. straight nitro-glycerine dynamite.” In other words, the 
less the unit deflective charge the greater is the propulsive capacity of 
the explosive. Different grades of '.N.T. give results varying from 
109 to 114 as compared with 100 for 40 per cent. dynamite. 
“Rate of detonation ” is a measure of the ability of an explosive to 
disrupt or shatter material in which it is exploded. In other words, it | 
is not only the-amount of force exerted which counts in an explosive, but 
time during which it acts. A very homely example will make this clear. 
Supposing a piano weighing 1,000 pounds requires a push of 100 pounds 
to start it rolling across the floor. If a man push slowly until he 
exerts that required 100-pound rolling pressure, the piano will move. 
But if he hit it with a 10-pound sledge hammer, with a sufficient force 
fo exert a pressure of 100 pounds on the end, he will not move the in- 
strument, but shatter the wooden end of it. 
It is so with an explosive. It is-not only, the unit deflective charge 
which is of use, but the rate at which that developed pressure takes 
effect. In blowing up a boulder of rock, a slow explosive may exert 
plenty of pressure and move the rock, while another, with half the 
pressure, but much more suddenly applied, may not succeed in moving 
the mass at all, as a mass, but will shatter it to fragments. 
Rate of detonation is measured in meters per second, and with 40 
per cent. dynamite on a scale of 100 T.N.T. grades from 94 to 102, 
according to quality. The rate of detonation of 40 per cent. dynamite 
is about 4,772 meters per second, and T.N.T. varies from 4,482 to 
4,852 meters per second—approximately the same. 
Tt is the shattering effect which made T.N.T. depth bombs so yalu- 
able in anti-submarine warfare. Several times as much gunpowder, for 
instance, in an ordinary “depth bomb” would, if exploded, in the same 
position do much less damage. It is the tremendous shattering effect 
of detonating compounds, such, for instance, as fulminate of mercury, 
which makes them valuable in setting off other explosives which have 
to be heavily jarred to explode. 
.. T.N-T. resists dampness very well, and therefore can be used in 
damp holes, with proper precautions not to break cartridge cases. When 
exploded, T.N.T. gives off dense volumes of black smoke. 
It may be interesting, as giving an idea of the real power of such 
“high” explosives as are here under consideration, to notice for a 
moment the results of what is known as the Trauzl block tests. Cavities 
are made in blocks of lead and various explosives set off. within these 
cavities. The increase of volume in the size of the cavity of a sub- 
stance like lead, which stretches with great resistance without shattering, 
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