OIL EXTRACTION FROM SEEDS 49 



being left in the press at varying stages of oil 

 expression. 



For cakes with 8 per cent, of oil, it takes approxi- 

 mately five minutes to fill a tier of cakes ready for 

 pressing, then five minutes under low pressure and 

 thirty minutes under high pressure (2 tons per square 

 inch) will complete the oil extraction. The cakes 

 are now taken out, their rough edges trimmed by 

 machinery, and after being cooled are ready for sale. 



When 12 per cent, oil is left in the cakes, the time 

 under low pressure is extended and that under high 

 pressure reduced. If, however, 16 per cent, oil is 

 required in the cake, the oil may be extracted entirely 

 under low pressure. A slightly lower temperature 

 may also be employed in the kettle for the meal before 

 expression. 



The cakes vary slightly in weight, but will run about 

 190 cakes to the ton ; i.e., 12 Ibs. each. 



Cotton Seed. This is grown chiefly in the tropics 

 viz., Egypt, India (Bombay), United States, South 

 America (Brazil), Salonica, etc. and consists of the 

 seed of the cotton plant (Gossypium). The seeds have a 

 considerable amount of cotton attached, which is doubt- 

 less intended by nature to aid their distribution by wind. 

 It is usual for the cotton-grower, after collecting the 

 seed, to send it to the ginning factory, where the cotton 

 lint is removed. It is then found that the seed has a 

 hard, brownish husk, with a whitish or greyish kernel 

 which is exceedingly rich in oil. The percentage, 

 however, varies according to the country of origin. 

 Egyptian seed may contain about 24 per cent, oil, 

 while the oil in American seed may be about 20 per 

 cent, Bombay less still (17 per cent). 



The seeds also differ in external appearance ; e.g., 



D 



