will show its value:--"A large wrought-iron tank, of 45 cubic feet
capacity, had been sunk level with the ground in the middle of the yard;
to this tank the gas had been laid on, for a purpose that will be
explained later on. The charges were fired by means of electricity, a
small dynamo firing machine being placed from 30 to 40 yards away from the
'mine.'" Operations were commenced by the top of the tank being covered
over and plastered down in order to make it air-tight; then a sufficient
quantity of coal gas was placed in it to make it highly inflammable and
explosive, the quantity being ascertained by a meter which had been fixed
specially for the purpose. Whilst the gas was being injected the cartridge
was prepared.

The first experiment was to try whether a small charge of tonite--fired
without the patent extinguisher--would ignite the gas. The gas having been
turned on, a miner's lamp was placed in the "tank," but this was
extinguished before the full quantity of gas had gone through the meter.
However, the gas being in, the charge of 1-1/4 oz. tonite was placed in
the "mine," the detonator was connected by means of long wires to the
dynamo machine, and the word was given to "fire." With a tremendous
report, and a flash of fire, the covering of the mine flew in all
directions, clearly showing that the gas had exploded. The next cartridge
(a similar charge) was prepared with the patent compound. First of all a
brown paper case of about 2 inches diameter was taken, and one of the
tonite cartridges was placed in the centre of it, the intervening space
between the charge and-the case being packed with the "fire-extinguishing
compound." The mine having had another supply of gas injected, the
protected cartridge was placed inside and fired. The result was
astonishing, the explosion not being nearly so loud, whilst there was not
the least flash of fire. "Protected" and "unprotected" charges were fired
at intervals, gas being turned into the tank on each occasion. Charges of