very suddenly when the decomposition of the nitro-glycerin was
completed.

3. The ordinary yellow solution of ammonium sulphide used in the
laboratory had the same effect as the K_{2}S. In this case the mixture
was evaporated to dryness on the steam bath, when bubbles of gas were
evolved, due to the decomposition of the ammonium nitrite. The pasty
mass of sulphur was treated with alcohol, which extracted the
glycerin, subsequently recovered by evaporation. Another portion of
the mixture of nitro-glycerin with ammonium sulphide was treated with
excess of PbCO_{3} and a little lead acetate, filtered, and the ammonium
nitrite detected in the solution. These qualitative results would be
expressed by the equation--

C3H5(NO)+3NH4HS = C3H5(OH)3 + 3NH4NO2 + S3,

which is similar to that for the action of potassium hydrosulphide
upon gun-cotton.

4. Flowers of sulphur and slaked lime were boiled with water, till a
bright orange solution was obtained. This was filtered, and some
nitro-glycerin powered into it. The reduction took place much more
slowly than in the other cases, and more agitation was required,
because the nitro-glycerin became coated with sulphur. In a few
minutes, the reduction appearing to be complete, the separated sulphur
was filtered off. The filtrate was clear, and the sulphur bore
hammering without the slightest indication of nitro-glycerin.

This would be the cheapest method of decomposing nitro-glycerin.
Perhaps the calcium sulphide of tank-waste, obtainable from the alkali