to have
considerable influence.

[Illustration: FIG. 54.--MORTAR FOR MEASURING THE BALLISTIC POWER OF
EXPLOSIVES. _A_, Shot; _B_, Steel Disc; _C_, Section of Mortar (Cast
Iron); _D_, Wooden Plug holding Explosive (_E_); _F_, Fuse.]

Mr T. Johnson made some ballistic tests. He used a steel mortar and a shot
weighing 29 Ibs., and he adopted the plan of measuring the distance to
which a given charge, 5 grms., would throw the shot. He obtained the
following results:--

Range in Feet.

Blasting gelatine (90 per cent. nitro-glycerine and nitro-cellulose) 392
Ammonite (60 per cent. Am(NO_{3}) and 10 per cent. nitro-naphthalene) 310
Gelignite (60 per cent. nitro-gelatine and gun-cotton) 306
Roburite (AmNO_{3} and chloro-nitro-benzol) 294
No. 1 dynamite (75 per cent. nitro-gelatine) 264
Stonite (68 per cent. nitro-gelatine and 32 per cent. wood-meal) 253
Gun-cotton 234
Tonite (gun-cotton and nitrates) 223
Carbonite (25 per cent. nitro-gelatine, 40 per cent. wood-meal,
and 30 per cent. nitrates) 198
Securite (KNO_{3} and nitro-benzol) 183
Gunpowder 143

~Calculation of the Volume of Gas Evolved in an Explosive Reaction.~--The
volume of gas evolved in an explosive reaction may be calculated, but only
when they are simple and stable products, such calculations being made at
0 deg. and 760 mm. Let it be required, for example, to determine the volume of
gas evolved by 1 gram-molecule of nitro-glycerine. The explosive reaction
of nitro-glycerine may be represented by the equation.

C_{3}H_{5}O_{3}(NO_{2})_{3} = 3CO_{2} + 2-1/2H_{2}O + 1-1/2N_{2} + 1/4O_{2}
By weight 227 = 132 + 45 + 42 + 8
By volume 2 = 3 + 2-1/2 + 1-1/2 + 1/4

The weights of the several products of the above reactions are calculated
by multiplying their specific gravities by the weight of 1 litre of
hydrogen at 0 deg. C. and 760 mm. (0.0896 grm). Thus,

One litre of CO_{2} = 22 x .0896 = 1.9712 grm.
" H_{2}O = 9 x " = 0.8064 "
" N_{2} = 14 x " = 1.2544 "
" O_{2} = 16 x " = 1.4336