The last portion of the table shows the economy which arises as the
whole apparatus gets properly heated. Thus the first make used 3
gallons naphtha per 1,000 cubic feet, the second 2 gallons 6 pints per
1,000 cubic feet, and the third 2 gallons 4 pints per 1,000 cubic
feet, and it is, therefore, not unreasonable to suppose that in a
continuous make these figures could be kept up, if not actually
reduced still lower.

In introducing the oil it is not injected, but is simply allowed to
flow in by gravity, at a point about half way up the column of fuel,
the taps for its admission being placed at intervals around the
circumference of the generator, and oil at first begins to flow down
the inside wall of the generator, but being vaporized by the heat, the
vapor is borne up by the rush of steam and water gas, and is cracked
to a permanent gas in the upper layer of fuel. This I think is the
secret of not being able to use heavier grades of oil, these being
sufficiently non-volatile to trickle down the side into the fire box
at the bottom, and so to escape volatilization. I have tried to
steam-inject the oil, but have not found that it yields any better
results.

One of the first things that strikes any one on seeing a make of gas
by this system is the enormous rapidity of generation. Mr. Leicester
Greville, who is chemist to the Commercial Gas Company, in reporting
on the process, says, "The make of gas was at the rate of about 86,000
cubic feet in 24 hours. A remarkable result, taking into consideration
the size of the apparatus." It is quite possible, with the small
apparatus, to make 100,000 cubic feet in 24 hours; indeed the run for
which the figures are given are over this estimate; and it must be
borne in mind that this rapidity of make gives the gas manager