to heat gun-cotton to 140° C. _in vacuo_, and to measure continuously by
means of a mercury manometer the pressure exerted by the evolved gases,
the latter being maintained at constant volume; the rate at which the
pressure increases is a measure of the rate of decomposition of the nitro-
cellulose.

SPECIFIC GRAVITIES OF EXPLOSIVES, &C.

Nitro-glycerine 1.6
Gun-cotton (dry) 1.06
" (25 per cent. water) 1.32
Dynamite No. 1 1.62
Blasting gelatine 1.54
Gelatine dynamite 1.55
Ballistite 1.6
Forcite 1.51
Tonite 1.28
Roburite 1.40
Bellite 1.2-1.4
Carbo-dynamite 1.5
Turpin's cast picric acid 1.6
Nitro-mannite 1.6
Nitro-starch 1.5
Emmensite 1.8
Mono-nitro-benzene 1.2
Meta-di-nitro-benzene 1.575 at 18° C.
Ortho-di-nitro-benzene 1.590 "
Para-di-nitro-benzene 1.625 "
British gunpowder, E.X.E. 1.80
" " S.B.C. 1.85