gun-cotton). It is, however, rendered much less sensitive to shock. With
regard to the power of No. 1 dynamite, experiments made in lead cylinders
give the relative value of No. 1 dynamite, 1.0; blasting gelatine, 1.4;
and nitro-glycerine, 1.4. The heat liberated by the sudden explosion of
dynamite is the same as its heat of combustion,[A] and proportionate to
the weight of nitro-glycerine contained in the mixture. The gases formed
are carbonic acid, water, nitrogen, and oxygen.

[Footnote A: Berthelot, "Explosives and their Power."]

The "explosive wave" (of Berthelot) for dynamite is about 5,000 metres per
second. At this rate the explosion of a cartridge a foot long would only
occupy 1/24000 part of a second, while a ton of dynamite cartridges about
7/8 diameter, laid end to end, and measuring one mile in length, would be
exploded in one-quarter of a second by detonating a cartridge at either
end.[A] Mr C. Napier Hake, F.I.C., the Inspector of Explosives for the
Victorian Government, in his paper, "Notes on Explosives," says: "The
theoretical efficiency of an explosive cannot in practice be realised in
useful work for several reasons, as for instance in blasting rock--

"1. Incomplete combustion.

"2. Compression and chemical changes induced in surrounding material.

"3. Energy expended in cracking and heating of the material which is not
displaced.

"4. The escape of gas through the blast-hole and the fissures caused by
the explosion.