16 BULLETIN 1010, U. S. DEPARTMENT OF AGRICULTURE. 



were very nearly the same color, B having less red but slightly more 

 yellow than A. In fact, after two hours of treatment a comparison 

 of the two oils leads to the conclusion that the color of the finished 

 oil is not materially dependent upon the germs from which it is pro- 

 duced, whether from the dry or the wet process. 



REFINING 10-POUND BATCHES OF CORN OIL TO DETERMINE THE COST 

 OF THE CHEMICALS USED AND THE VALUE OF THE OIL LOST. 



On the basis of conclusions drawn from the foregoing experiments 

 on small quantities of oil, two batches of 10 pounds each were refined. 

 The oil was obtained from a hominy plant and was therefore produced 

 from dry-process germs. It contained 1.76 per cent of free fatty 

 acids. One of the 10-pound batches was treated with caustic accord- 

 ing to method 1, and the other batch according to method 2. 



TREATMENT WITH CAUSTIC. 



The 10-pound batch of oil to be treated by method 1 was placed 

 in a 12-quart enameled bucket. A pound of 10° Be. caustic was 

 added and the mixture stirred for 30 minutes. Heat was then applied 

 slowly with continued stirring over a period of 15 minutes until a 

 temperature of 55° C. was reached. The break occurred as the 

 temperature reached 45° C. The oil was warmed for three hours m a 

 water bath at 55° C. and then allowed to cool to room temperature 

 by standing overnight. 



The oil, which will be designated C, was removed from the soap- 

 stock by suction through a rubber tube which could be moved about 

 over the surface of the soapstock, a method similar to the com- 

 mercial practice of pumping off the oil and skimming off the last 

 portion by means of a swivel pipe. The soapstock was of a soft- 

 petrolatum consistency, and the oil could all be drawn off with the 

 exception of a thin layer. The refining loss was 6.05 per cent. 

 Heating the soapstock did not result in separating out any more of 

 the oil. 



The neutralized oil was turbid, owing to the presence of moisture 

 and soap. To remove the soap the oil was heated to 65° C. in the 

 bucket, with constant stirring, and 5 per cent of a 10 per cent brine 

 solution was added in a fine stream. Stirring was continued for 15 

 minutes and the oil then allowed to stand. The bulk of the brine 

 settled out rapidly, but a turbidity remained in the oil even after it 

 had stood all night. This turbidity was due to moisture rather than to 

 soap, since heating completely clarified the oil and left no particles 

 of soap in suspension, as was the case before the oil was washed. 



The other 10-pound batch of oil was treated with 14° Be\ caustic 

 according to method 2. The quantity required to neutralize the 



