COTTON 287 



OIL IN THE REFINING TANK 



Crude oil when taken from the settling tanks 

 may be either shipped direct to refineries, or if, as 

 is often the case, a refinery is located in connection 

 with the oil mill, it may be refined at once. 



In the refining process oil is heated gently, 

 stirred constantly, and treated freely with air which 

 enters through a perforated pipe at bottom. Im- 

 purities are still present in the crude oil, and these 

 are partially gotten rid of through the free use of 

 caustic soda or potash; this coagulates them, 

 causing them to collect and fall to the bottom of 

 the tank. The next step is to draw off the oil and 

 make the final preparation for its shipment. Be- 

 fore it can go, however, it must be washed with 

 water in order that the potash may be dissolved 

 and removed. Since oil is lighter than water, 

 separation gradually takes place in the mixture and 

 the oil slowly rises to the top where it is carefully 

 drawn off, at last to be filtered and put into barrels. 



WHAT IS MADE FROM THE OIL 



Refined oil is known as " summer yellow" and of 

 course, is of a higher commercial value than the 

 crude oil. Prime summer yellow is known as 

 butter oil, and is largely used in the manufacture of 

 oleomargarine, butterine and even as an adulterant 

 for butter itself. 



The highest grade of summer yellow is often 

 subjected to cold pressure, which gives a product 

 known as salad oil for cooking, dressing, and other 

 household products. Then, too, large quantities 

 of summer yellow have for a long time found their 

 way into Italy where it is treated, to be sent later to 



