"Cotton seed oil," said Mr. A.E. Thornton, of the Atlanta mills, "is
one of the most valuable of oils because it is a neutral oil, that is,
neither acid nor alkali, and can be made to form the body of any other
oil. It assimilates the properties of the oil with which it is mixed.
For instance, olive oil. Cotton seed oil is taken and a little extract
of olives put in. The cotton oil takes up the properties of the
extract, and for all practical purposes it is every bit as good as the
pure olive oil. Then it is used in sweet oil, hair oil, and, in fact,
in nearly all others. A chemist cannot tell the prepared cotton oil
from olive oil except by exposing a saucerful of each, and the olive
oil becomes rancid much quicker than the cotton oil. The crude oil is
worth thirty cents a gallon, and even as it is makes the finest of
cooking lard, and enters into the composition of nearly all lard."
A visit to the mills showed how the oil is made. From the platform
where the seed is unloaded it is thrown into an elevator and carried
by a conveyor--an endless screw in a trough--to the warehouse. Then it
is distributed by the conveyor uniformly over the length of the
building--about 200 feet. The warehouse is nearly half filled now, and
thousands and thousands of bushels are lying in store. Another
elevator carries the seed up to the "sand screen." This is a revolving
cylinder made of wire cloth, the meshes being small enough to retain
the seed, which are inside the cylinder, but the sand and dirt escape.
Now the seeds start down an inclined trough. There is something else
to be taken out, and that is the screws and nails and rocks that were
too large to be sifted out with the sand and dirt. There is a hole in
the inclined trough, and up through that hole is blown a current of
air by a suction fan. If it were not for the fan, the cotton seed,
rocks, nails, and all would fall through. The current keeps up the
cotton seed, and they go on over, but it is not strong enough to keep
up the nails and pebbles, and they fall through. Now the seed, free of
all else, is carried by another elevator and endless screw conveyor to
the "linter." This is really nothing more than a cotton gin with an
automatic feed.
"HULLER" AND "HEATERS."
Then the seed is carried to the "huller," where it is crushed or
ground into a rough meal about as coarse as the ordinary corn "grits."
The next step is to separate the hulls from the kernels, all the oil
being in the kernel, so the crushed seed is carried to the
"separator." This is very much on the style of a sand screen, being a
revolving cylinder of wire cloth. The kernels, being smaller than the
broken hulls, fall through the broken meshes, and upon this principle
the hull is separated and carried direct to the furnace to be used as
fuel. The kernels are ground as fine as meal, very much as grist is
ground, between corrugated steel "rollers," and the damp, reddish
colored meal is carried to the "heater."
The "heater" is one iron kettle within another, the six inch steam
space between the kettles being connected direct with the boilers.
There are four of these kettles side by side. The meal is brought into
this room by an elevator, the first "heater" is filled, and for twenty
minutes the meal is subjected to a "dry cook," a steam cook, the steam
in the packet being under a pressure of forty-five pounds. Inside the
inner kettle is a "stirrer," a revolving arm attached at right angles
to a vertical shaft. The stirrer makes the heating uniform, and the
high temperature drives off all the water in the meal, while the
involatile oil all remains.
In five minutes the next heater is filled, in five minutes the next,
etc.
Now there are four "heaters," and as the last heater is filled--at the
end of twenty minutes--the first heater is emptied. Then at the end of
five minutes the first heater is filled, and the one next to it is
emptied, and the rotation is kept up, each heater full of meal being
"dry-cooked" for twenty minutes.
Corresponding to the four heaters are four presses. Each press
consists of six iron pans, shaped like baking pans, arranged one above
the other, and about five inches apart. The pans are shallow, and
around the edge of each is a semicircular trough, and at the lowest
point of the trough is a funnel-shaped hole to enable the oil to run
from one pan to the next lowest, and from the lowest pan to the
"receiving tanks" below.