t to the
gas main leading to the various places where it is to be consumed. The
hot water obtained in this second scrubber is passed through a vessel
suitably constructed for separating the tar which is mixed with it,
and is then pumped through a third scrubber, through which, in an
opposite direction to the hot water, cold air is passed. This is
forced by means of a Roots blower through the scrubber into the
producer.

The air gets heated to about 76 deg. C. and saturated with moisture at
that temperature by its contact with the hot water, and the water
leaves this third scrubber cold enough to be pumped back through the
second scrubber. The same quantity of water is thus constantly used
for condensing the water vapor in one scrubber and giving it up to the
air in the other. In this way we recover and return to the producer
fully two-thirds of the steam which has been originally introduced, so
that we have to add to the air, which has thus been loaded with
moisture, an additional quantity of steam equal to only one-third of
the total quantity required before it enters the producer. This
additional quantity of steam, which amounts to 0.6 ton of steam for
every ton of fuel burnt, we obtain as exhaust steam from the engines
driving the blowers and pumps required for working the plant.

The gas producers which I prefer to use are of rectangular shape, so
that a number of them can be put into a row. They are six feet wide
and 12 feet long inside. The air is introduced and the ashes removed
at the two small sides of the producer which taper toward the middle
and are closed at the bottom by a water lute of sufficient depth for
the pressure under which the air is forced in, equal to about 4 inches
of water. The ashes are taken out from underneath the water, the
producers having no grate or fire bars at all. The air enters just
above the level of the water through a pipe connected with the blower.
These small sides of the producer rest upon cast iron plates lined to
a certain height with brickwork, and this brickwork is carried by
horizontal cast iron plates above the air entrance. In this way a
chamber is formed of triangular shape, one side of which is closed by
the ashes, and thus the air is distributed over the whole width of the
producer.

The gas is taken out in the middle of the top of the producer by an
iron pipe, and fuel charged in by hoppers on both sides of this pipe.
Between the pipe and the hoppers two hanging