generator, the oil is fed into it, and, with the gas, passes through a
D-shaped retort tube, which is arranged round three sides of the top
of the generator; and in this the oil is volatilized, and passes, with
the gas, to the bottom of the superheater, in which the vapors are
converted into permanent gases.

The Van Steenbergh plant, with which I have been experimenting for
some time, stands apart from all other forms of carbureted water gas
plant, in that the upper layer of the fuel itself forms the
superheater, and that no second part of any kind is needed for the
fixation of the hydrocarbons, an arrangement which reduces the
apparatus to the simplest form, and leaves no part which can choke or
get out of order, an advantage which will not be underrated by any one
who has had experience of these plants. While, however, this enormous
advantage is gained, there is also the drawback that the apparatus is
not fitted for use with crude oils of heavy specific gravity, such as
can be dealt with in the big external superheaters of the Lowe class
of water gas plant, but the lighter grades of oil must be used in it
for carbureting purposes.

I am not sure in my own mind that this, which appears at first a
disadvantage, is altogether one, as, in the first place, the lighter
grades of oil, if judged by the amount of carbureting power which they
have, are cheaper per candle power, added to the gas, than the crude
oils, while their use entirely does away with the formation of pitch
and carbon in the pipes and purifying apparatus--a factor of the
greatest importance to the gas manufacturer.

The fact that light oils give a higher carburation per gallon than
heavy crude oil is due to the fact that the latter have to be heated