26 BULLETIN 867, U. S. DEPARTMENT OF AGRICULTURE. 
vided with indicators to record the level of the contents, or when 
buried under ground with indicators above ground to register the 
contents. 
Heretofore there has not ‘Been much inducement for manufacturers 
to prepare a high-grade No. 3 oil. Consequently, the generally 
recognized darkening effect of heat due to steaming off has not been 
considered. If, however, effort is made to produce a high-grade oil 
with a minimum of color, ‘care must be exercised not to expose 
the oil in the solvent-recovery still or oil-finishing still to this high 
temperature. 
By such solvent cmnRcuon, as generally practiced, a pomace is 
produced running from 10 to 12 per cent of moisture and containing 
anywhere from 0.6 to 2 per cent of oil. This low content of oil can 
be attained only by very efficient extraction, determined by the kind 
of solvent used, the number and efficiency of the washings, and the 
type of equipment. 
SOLVENT-EXTRACTED NO. 1 OIL. 
In the course of the work of this laboratory on the technology of 
castor-oill manufacture, evidence has been obtained which indicates 
that a very promising oil of apparently No. 1 grade can be made 
entirely by the solvent process. Without decorticating the beans, 
they were slightly crushed in order to break the seed coats and ex- 
tracted with benzol by percolation. The solvent saturated with _ 
oil was of a characteristic light-green color, similar to oil always 
produced by such extraction. The benzol was evaporated at atmos- 
pheric pressure until toward the end of the distillation, whereupon 
a yacuum was applied. The residual oil with greenish yellow color 
was then heated to 95° to 110° C. at atmospheric pressure and treated 
with 5 per cent of fuller’s earth with constant agitation for about 
10 mimutes, whereupon 2 per cent of decolorizing carbon was added 
and the stirrmg continued, while the temperature was allowed to 
fall slowly to about 90° C. At the expiration of about 15 minutes 
the oil was filtered and came through with a light straw color. Inas- 
much as every castor-oil expelling plant must -have an auxiliary 
extraction equipment, it follows that if a satisfactory grade of oil, 
colorless and low in acidity, can be made by such means it will mate- 
rially reduce the cost of production. 
TREATMENT OF POMACE. 
The dry, more or less dusty pomace from the extraction house is 
conveyed to the pomace warehouse. If it is lumpy, it is passed 
through a grinding machine, which may be of the rotating-disk type, 
spiked-roller (crusher), or swinging-hammer type, where it is pulver- 
ized. If the moisture runs above 12 per cent, decomposition may 
set in, resulting in an appreciable loss of ammonia, the only con- 
stituent of real commercial value. 
