a
little bit of lime or plaster become accidentally mixed with it, it may
become highly dangerous. A local explosion may occur which might have the
effect of causing the explosion of the whole mass. Picric acid can be
fired by a detonator, 5-grain fulminate, and M. Turpin patented the use of
picric acid, unmixed with any other substance, in 1885. The detonation of
a small quantity of dry picric acid is sufficient to detonate a much
larger quantity containing as much as 17 per cent. of water.

It is chiefly due to French chemists (and to Dr Sprengel) that picric acid
has come to the front as an explosive. Melinite,[A] a substance used by
the French Government for filling shells, was due to M. Turpin, and is
supposed to be little else than fused picric acid mixed with gun-cotton
dissolved in some solvent (acetone or ether-alcohol). Sir F.A. Abel has
also proposed to use picric acid, mixed with nitrate of potash (3 parts)
and picrate of ammonia (2 parts) as a filling for shells. This substance
requires a violent blow and strong confinement to explode it. I am not
aware, however, that it has ever been officially adopted in this country.
Messrs Designolles and Brugere have introduced military powders,
consisting of mixtures of potassium and ammonium picrates with nitrate of
potassium. M. Designolles introduced three kinds of picrate powders,
composed as follows:--

___________________________________________________________________
| | | | |
| | For Torpedoes | For Guns. | For Small |
| | and Shells. | Ordinary. Heavy. | Arms. |
|___________________|_______________|___________________|___________|
| | | | | |
| Picrate of Potash | 55-50 | 16.4- 9.6 | 9 | 28.6-22.9 |
| Saltpetre | 45-50 | 74.4-79.7 | 80 | 65.0-69.4 |
| Charcoal | ... | 9.2-10.7 | 11 | 6.4- 7.7 |
|___________________|_______________|___________|_______|___________|

They were made much like ordinary gunpowder, 6 to 14 per cent. of moisture
being added when being milled. The advantages claimed over gunpowder are
greater strength, and consequently greater ballistic or disruptive effect,
comparative absence of smoke, and freedom from injurious action on the
bores of guns, owing to the absence of sulphur. Brugere's powder is
composed of ammo