6 BULLETIN 1475, U. S. DEPARTMENT OF AGRICULTURE 
A measured quantity of the cooked meats is dropped upon a strip 
of press cloth in the cake former — a press with a steel block con- 
taining in its upper surface a shallow groove the size of a single 
press box. It is so constructed that after the meal has been placed 
upon the press cloth, and the two ends turned up over the charge, 
pressure can be applied, and the cake, now covered with cloth 
except on its two long sides, can be subjected to a preliminary squeez- 
ing to make it compact. Pressure is applied to the charge in the 
cake former for an instant and then released. A. sheet of steel the 
width of the groove is slid beneath the cake, which is removed, 
cloth and all, from the cake former and placed in the lowest frame 
of the press. 
One after the other, all the frames or boxes are thus charged 
until the press is filled. The compressed air is then turned on grad- 
ually and the piston or ram forces the frames upward, each against 
the one above it. The oil squeezed through the cloths flows over 
the sides of the press into the gallery around the bottom frame and 
out through the trough to the settling cistern or tank. So perfectly 
has every detail for the operation of these large presses been planned 
that they are often filled, pressed, and discharged in less than half 
an hour. 
The expeller, a continuous press, which is rapidly gaining favor 
among American cottonseed crushers, has an interrupted screw 
revolving inside a slotted steel barrel. The crushed seed or meats 
enter through a hopper at one end of the barrel, are passed along 
toward the other end, and are finally discharged around a cone, 
which can be set in or out of the outlet to give any desired pressure. 
Expellers are used for making cold-pressed and hot-pressed oil. 
The term cold-pressed is not strictly applicable to oil made in this 
way, because the seeds or meats, as the case may be, are tempered 
or warmed to some extent in the temperer above the expeller and 
are also heated by the friction in the expeller, so that the oil and 
cake come out warm, sometimes actually hot. Although the crude 
oil thus obtained differs from that obtained by regular hot pressing, 
it becomes the same after it has been refined. 
SETTLING 
The crude oil, whether obtained by using the hydraulic press or 
the expeller, contains some fine meal. It is customary to allow the 
oil to stand in settling tanks so that this meal will settle. The clear 
oil is then withdrawn and sent to the refinery. 
RETIRING 
The crude oil received at the refinery is either transferred to the 
storage tanks or placed directly in the weighing tanks. It next goes 
to the refining kettles, tall cylindrical tanks with conical bottoms, 
provided with steam heating coils that extend part way up the sides, 
and a mechanical agitator. After the weighed quantity of oil to be 
refined has been warmed, if necessary, to about 85° F. the agitator is 
started and the proper quantity of caustic soda solution for this par- 
ticular lot of oil, as determined previously by the chemist, is added. 
The agitation and heating are continued until the brown particles of 
