The Residue left after treating the gelatine with ether-alcohol is, in the case of blasting gelatine, very small, and will probably consist of nothing but carbonate of soda.  It should be dried at 100 deg.  C. and weighed, but in the case of either gelignite or gelatine dynamite this residue should be transferred to a beaker and boiled with distilled water, and the water decanted some eight or ten times, and the residue finally transferred to a tarred filter and washed for some time with hot water.  The residue left upon the filter is wood-pulp.  This is dried at 100 deg.  C. until constant, and weighed.  The solution and washings from the wood are evaporated down in a platinum dish, and dried at 100 deg.  C. It will consist of the potassium nitrate, and any other mineral salts, such as carbonate of soda, which should always be tested for by adding a few drops of nitric acid and a little water to the residue, and again evaporating to dryness and re-weighing.  From the difference in weight the soda can be calculated, sodium nitrate having been formed.  Thus—­

Na_{2}CO_{3} + 2HNO_{3} = 2NaNO_{3} + CO_{2} + H_{2}O.

Mol. wt. = 106 = 170

(170 — 106 = 64) and x = (106 x d)/64

where 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.