10 
BULLETIN 139, U. S. DEPARTMENT OF AGRICULTURE. 
the soy bean are similar to those employed with other oil seeds, such 
as cottonseed and linseed. 
In Manchuria the manufacture of oil and oil cake is not confined 
to large centers, as every small center of bean production has its 
native mill. The method of extracting oil in these native mills is 
decidedly primitive. The beans are first crushed beneath a mill- 
stone and then steamed for about 15 minutes. The resultant mass 
is spread out and placed in circular iron frames, about 6 inches deep. 
Five of these frames are placed one above another in a vertical press, 
consisting of four uprights, with crossbeams at the top and bottom. 
Pressure is applied by means of wedges driven in between the cross- 
JFig. 3.— Coolies at Xewchwang, Manchuria, engaged in carrying loads of soy beans from the junks to big 
stacks, where they are kept until the factory needs them for oil manufacture. (Photographed by F . X . 
Meyer.) 
beams and beams placed on top of the frames, and the oil is thus 
expressed. During the last few years large bean mills equipped with 
modern machinery have been erected, and these are able to extract 
3 or 4 per cent more oil (fig. 3). In these large bean mills only about 
one-half the oil is extracted by the usual process: that is. by crushing 
the beans, steaming them, and using hydraulic pressure. 
A solvent process of extraction, involving the use of benzine, has 
recently come into use in several English mills, and three such mills 
are in operation in Manchuria and Japan. The seeds are first finely 
crushed and then treated directly by the fat solvent. The oil is 
then taken out of the fat solvent by evaporating the latter, which 
is distilled and used over again. The residue is well dried and then 
ground into a fine meal, which is said to contain no detectable trace 
