CASTOR-OIL INDUSTRY. 



17 



Usually they contain from. 12 to 20 per cent of oil, 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 



Fig. 7. — A cage filling press. 



Fig. 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 

 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 per cent. 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 



