x_ equals grms. of sodium carbonate in residue, and _d_ equals the
difference in weight of residue, before and after treatment with nitric
acid.

The nitro-glycerine is best found by difference, but if desired the
solutions from the precipitation of the nitro-cellulose may be evaporated
down upon the water bath at 30 deg. to 40 deg. C., and finally dried over CaCl_{2}
until no smell of ether or chloroform can be detected, and the nitro-
glycerine weighed. It will, however, always be much too low. An actual
analysis of a sample of gelatine dynamite gave the following result:--

Nitrocellulose (collodion) 3.819 per cent.
Nitro-glycerine 66.691 "
Wood-pulp 16.290 "
KNO_{3} 12.890 "
Na_{2}CO_{3} _Nil._
Water 0.340 "

This sample was probably intended to contain 30 per cent. of absorbing
material to 70 per cent. of explosive substances. Many dynamites contain
other substances than the above, such as paraffin, resin, sulphur, wood,
coal-dust, charcoal, also mineral salts, such as carbonate of magnesia,
chlorate of potash, &c. In these cases the above-described methods must of
course be considerably modified. Paraffin, resin, and most of the sulphur
will be found in the ether solution if present. The solution should be
evaporated (and in this case the explosive should in the first case be
treated with ether only, and not ether-alcohol), and the residue weighed,
and then treated on the water bath with a solution of caustic soda. The
resin goes into solution, and is separated by decantation from the
residue, and precipitated by hydrochloric acid, and collected on a tarred
filter (dried at 100 deg. C.), and dried at 100 deg. C. and weighed. The nitro-
glycerine residue is treated with strong alcohol, decanted, and the
residue of paraffin and sulphur washed with alcohol, dried, and weighed.

To separate the paraffin from the sulphur the residue is heated with a
solution of ammonium sulphide. After cooling the paraffin collects as a
crust upon the surface of the liquid, and by pricking a small hole through
it with a glass rod the liquid underneath can be poured off, and the
paraffin then washed with water, dried, and weighed. Sulphur is found by
difference. Mr F.W. Smith (_Jour. Amer. Chem. Soc._, 1901, 23 [8],
585-589) determines the sulphur in dynamite gelatine as follows:--About 2
grms. are warmed in a 100 c.c. silver