22 BULLETIN 867, U. S. DEPARTMENT OF AGRICULTURE. 



2.46 gallons (19.7 pounds) of No. 1 oil, containing about 10 per cent 

 of meal. The beans assayed 48.4 per cent oil. Inasmuch as there 

 is normally about 2 per cent of trash with an additional loss of about 

 1 pound per bushel for shrinkage, it follows that the oil content of the 

 cake was about 11.6 per cent. The No. 1 oil was agitated with 5 

 per cent fuller's earth and 2 per cent filtchar at 85° to 90° C. for 

 10 minutes, then for 15 minutes at 70° to 85° C, and filtered. A very- 

 light colored oil was obtained. The above pressure was too great, 

 however, for satisfactory mill operation. 



Messrs. Pinnock and Goetz, of the Bureau of Aircraft Production, 

 expelled the oil from a batch of beans in the hull in order to test the 

 possibility of obviating the expense of maintaining hulling stations 

 scattered over the country, and also of assembling in one place all 

 merchantable castor-bean products. By such practice all hulls are 

 included in the residual pomace as fertilizer, the costs of hulling and 

 attendant contractor commissions are eliminated, shipping costs are 

 reduced by eliminating bagging, while an oil of lower acidity is 

 obtained, owing to the protection of the brittle seed coats from 

 cracking during handling. The great disadvantage, however, is that 

 a green-colored oil is produced. For lubricating purposes this is of 

 little moment, but in ordinary trade it is unacceptable. However, 

 the oil can readily be bleached by refining it first with alkali and then 

 bleaching with fuller's earth and carbon. From 258^ pounds of 

 beans in the hull, 79| pounds of oil and 166| pounds of cake were 

 obtained. Since the original oil content of the beans was 34.5 per 

 cent, it follows that the operation yielded about 92.75 per cent of the 

 total oil. No oil was lost by absorption in the extra cake, owing 

 to the fact that the hulls themselves contained 6.4 per cent of oil. 



Unless proper care and skill are applied in using the expellers 

 the machines produce an oil high in meal. To prevent this, it is 

 necessary that the proper amount of moisture be present, and that 

 the beans be heated. On starting a cold expeller, a thick mass of 

 meal and oil is produced, but after running about half an hour the 

 machine warms up and produces an oil with apparently no more 

 meal than that from a hydraulic cage press. In a day's run of seven 

 hours there is produced only about 1 cpuart of such meal by each 

 machine. Oil made in expellers is certainly heated to higher tem- 

 peratures than obtain in cage pressing. As it drips through the 

 bars it has an average temperature of about 176° F., while that 

 of the cake as it emerges at the discharge is about 133° F. So little 

 deleterious effect is produced on the oil by this heat that it must 

 be attributed to the extremely short duration of the exposure. 



The expellers in the Gainesville plant have been regularly operat- 

 ing on 800 pounds, or about 17 to 18 bushels of beans an hour, but 

 under forcing ran do materially more. A test on an experimental 



