is 714 litres per kilo, the water being taken as gaseous. Nitro-glycerine
is decomposed differently if it is ignited as dynamite (i.e., kieselguhr
dynamite), and if the gases are allowed to escape freely under a pressure
nearly equal to that of the atmosphere. Sarrau and Vieille obtained under
these conditions, for 100 volumes of gas--

NO 48.2 per cent.
CO 35.9 "
CO_{2} 12.7 "
H 1.6 per cent.
N 1.3 "
CH_{4} 0.3 "

These conditions are similar to those under which a mining charge, simply
ignited by the cap, burns away slowly under a low pressure (i.e., a miss
fire). In a recent communication, P.F. Chalon (_Engineering and Mining
Journal_, 1892) says, that in practice nitro-glycerine vapour, carbon
monoxide, and nitrous oxide, are also produced as the result of
detonation, but he attributes their formation to the use of a too feeble
detonator.

Nitro-glycerine explodes very violently by concussion. It may be burned in
an open vessel, but if heated above 250° C. it explodes. Professor C.E.
Munroe gives the firing point as 2O3°-2O5° C., and L. de Bruyn[A] states
its boiling point as 185°. He used the apparatus devised by Horsley. The
heat of formation of nitro-glycerine, as deduced from the heat of
combustion by M. Longuinine, is 432 calories for 1 grm.; and the heat of
combustion equals 1,576 cals. for 1 grm. In the case of nitro-glycerine
the heat of total combustion and the heat of complete decomposition are
interchangeable terms, since it contains an excess of oxygen. According to