e by placing the
cartridges in a warming pan, which consists of a tin can, with double
sides and bottom, into which hot water (130 deg. Fahr.) can be poured. The
dynamite will require to be left in for some considerable time before it
becomes soft. On no account must it be placed on a hot stove or near a
fire, as many serious accidents have occurred in this way.

Frozen dynamite is a hard mass, with altered properties, and requires 1.5
grm. of fulminate instead of 0.5 grm. to explode it. Thawing may also
cause exudation of the nitro-glycerine, which is much more sensitive to
shock, and if accidentally struck with an iron tool, may explode. It is a
dangerous thing to cut a frozen cartridge with a knife. Ramming is even
more dangerous; in fact it is not only dangerous, but wasteful, to use
dynamite when in a frozen state.

Dynamite explodes at a temperature of 360 deg. Fahr., and is very sensitive to
friction when hot. In hot countries it should never be exposed to the rays
of the sun. It should, however, not be kept in a damp or moist place, as
this is liable to cause exudation. Sunlight, if direct, can cause a slow
decomposition, as with all nitro and nitric compounds. Electric sparks
ignite, without exploding it, at least when operating in the open air.

Dynamite, when made with neutral nitro-glycerine, appears to keep
indefinitely. Sodium or calcium carbonate to the extent of 1 per cent. is
often added to dynamite to ensure its being neutral. If it has commenced
to undergo change, however, it rapidly becomes acid, and sometimes
explodes spontaneously, especially if contained in resisting envelopes.
Nevertheless, neutral and well-made dynamite has been kept for years in a
magazine without loss of its explosive force. If water is brought into
contact with it, the nitro-glycerine is gradually displaced from the
silica (guhr). This action tends to render all wet dynamite dangerous.

It has been observed that a dynamite made with wood sawdust can be
moistened and then dried without marked alteration, and from 15 to 20 per
cent. of water may be added to cellulose dynamite without depriving it of
the power of exploding by strong detonator (this is similar to wet
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 b