CASTOR-OIL, INDUSTRY. alive 
Usually they contain from 12 to 20 per cent of oul, according to the 
length of the pressing cycle and the pressure applied. These high 
percentages of oil in the cakes are caused by the presence of the 
seed coats, which form little cups throughout the mass and prevent 
ready draining of the oil and crushing of the kernels. So incomplete 
is the crushing that the kernels often retain their original shape. 
On the other hand, it has been stated that the application of too 
great a pressure produces oil which precipitates an albuminlike 
product on standing. Thus, like most commercial operations, there 
nee 
Fig. 7.—A cage filling press. Fic. 8.—A cage discharging press, used to remove 
the cakes. 
comes a point where a satisfactory balance is struck between quan- 
tity and quality, beyond which the operator sacrifices profits. Good 
practice yields about 15.6 pounds of No. 1 cold-pressed oil to the 
_g bushel of beans, with 4.3 pounds remaining in the cake as No. 3 
oil, assuming 46 pounds of beans to the bushel and an oil content of 
45 percent. Such large percentages of oil in the cake, together with 
the high prices of the oil, warrant treatment of the cake for the 
recovery of this oil. This, of course, can be accomplished only by 
solvent extraction. 
182601°—20——3 
