ct requires a case with from 0.70 to 0.90
carbon, but where there is a large variety of work the compound
may be so handled that there will be practically no waste.

This is accomplished with one of the most widely known artificial
carburizers by giving all the compound in the plant three distinct
classifications: "New," being direct from the maker; "half and
half," being one part of new and one part first run; and "2 to 1,"
which consists of two parts of old and one part new.

SEPARATING THE WORK FROM THE COMPOUND

During the pulling of the heat, the pots are dumped upon a cast-iron
screen which forms a table or apron for the furnace. Directly beneath
this table is located one of the steel conveyor carts, shown in Fig.
43, which is provided with two wheels at the rear and a dolly clevis
at the front, which allows it to be hauled away from beneath the
furnace apron while filled with red-hot compound. A steel cover is
provided for each box, and the material is allowed to cool without
losing much of the evolved gases which are still being thrown off
by the compound.

[Illustration: FIG. 43.--The cooling carts.]

[Illustration: FIG. 44.--Machine for blending the mixture.]

As this compound comes from the carburizing pots it contains bits
of fireclay which represent a part of the luting used for sealing,
and there may be small parts of work or bits of fused material
in it as well. After cooling, the compound is very dusty and
disagreeable to handle, and, before it can be used again, must be
sifted, cleaned and blended.

Some time ago the writer was confronted with this proposition for
one of the largest consumers of carburizing compound in the world,
and the problem was handled in the following manner: The cooled
compound was dumped from the cooling cars and sprinkled with a
low-grade oil which served the dual purposes of settling the dust
and adding a certain percentage of valuable hydrocarbon to the
compound. In Fig. 44 is shown the machine that was designed to do
the cleaning and blending.

BLENDING THE COMPOUND

Essentially, this consists of the sturdy, power-driven separator
and fanning mill which separates the foreign matter from the compound
and elevates it into a large settling basin which is formed by
the top of the steel housing that incloses the apparatus. After
reaching the settling basin, the compound falls by gravity into
a power-driven rotary mixing tub which is directly beneath the
settling basi