CASTOR-OIL INDUSTRY. ys 
expeller indicated a possible thousand pounds, or an hourly rate 
of 21 bushels. In the expeller plant at Gainesville, the machines 
were not set to yield more than about 15 pounds of oil per 46-pound 
bushel. . 
The relative quality of expeller castor oil compared with that’ 
of hydraulic pressed oil will be considered later. 
SOLVENT EXTRACTION. 
On account of the large proportion of residual castor oil left in 
the cake from the pressing or expelling operation, namely, from 12 
to 20 per cent, or about 5 pounds per 46-pound bushel, solvent 
extraction of the cake is universally practiced in this country, follow- 
ing the methods generally applicable to oleaginous products. The 
units comprising a complete extraction plant consist of the extractor 
and the solvent-recovery still, the oil-finishing still, the condenser, 
the solvent and water separator, pumps, and storage tanks. 
Two general types of equipment are used, namely, the stationary. 
extractor and the rotary extractor. The former is primarily an 
_ English development, while the latter is American, having found 
extensive application in the extraction of garbage and other waste 
materials where the great problem is to handle in an economical 
manner bulky products with small oil content. - 
The iron stationary extractors vary in dimensions, but may have 
a diameter of 6 to 8 feet and a height of 10 to 12 feet, entirely inclosed, 
with, however, apertures for loading and discharging and also stirrers 
and vapor pipes. The extractor is provided with a false bottom, 
perforated over its entire surface with small openings, varying in 
size with the character of the material to be extracted. These 
openings may be over an inch in diameter, but if finer materials ~ 
are to be extracted auxiliary plates with smaller perforations may 
be laid on. 
In order to obviate channeling in castor-pomace extraction, 
attempts have been made to operate a stirrer, but owing to the 
tendency of such material to pack during extraction it has been 
found impracticable to operate such stirrers when the extractors 
are charged to anything lke their capacity. Accordingly, recourse 
is had to auxiliary methods of breaking up channeling in extraction, 
as well as in ‘‘steaming off” the solvent in the final treatment. 
Another difficulty of stationary extractors is that there is a tend- 
ency for materials containing large quantities of nonfibrous albu- 
minous material to pack on the bottom, which very effectively 
precludes the circulation of the solvent, so essential to the efficiency 
of extraction. Among the methods which have been used to 
obviate this packing tendency of castor beans is that of laying 
burlap between quarter-inch chicken wire over the floor, spreading 
