CASTOR-OIL INDUSTRY. 



27 



FINISHING THE OIL. 



Various methods are recorded in the literature for refining castor 

 oil. Among these may be mentioned acid refining by sulphuric 

 acid, settling of the foots, and subsequent washing out of the acid. 

 Other methods involve refining in alcoholic solution. As far as can 

 be ascertained, these methods are not generally applied. British 

 practice has long consisted in passing live steam into the oil, which 

 serves to coagulate and precipitate the albuminlike constituents, 

 which are filtered off. That this product is nitrogenous has been 

 demonstrated. The oils listed in Table VII were analyzed for 

 nitrogen. 



Table VII. — Analyses of castor-bean oils of diverse origin, showing nitrogen content. 



Source. 



Nitrogen (N X 6.25) content 

 (per cent). 



Raw. 



Treated. 



American . . . 



Newchwang 

 "Chinese".. 



0. 0159\ n nlK . 

 .0169/ - 0164 

 •03991 04 , 4 

 .0469/ - m6i 



iosl}- 0350 



/ 0.01631 

 \ .0163/ 



0. 0163 



. 01631 

 0183/ 



.0173 



Castor oil can not be freed from acid as readily as some of the other 

 staple oils, such as cottonseed and peanut oils. Instead of the soaps 

 breaking readily and settling out, the castor-oil soaps only partly do 

 so but have a tendency also to dissolve in the oil, rendering the latter 

 very viscous and thick. Consequently, the oil has to be very 

 thoroughly washed to remove such. 



No. 1 castor oil is usually so low in acid that it serves all industrial 

 purposes without refining. However, there are times when the oil 

 may run high in acid, on account of the character of the beans 

 received at a given plant, or the acidity may run up, owing to factory 

 troubles. All No. 3 oil is high in acidity, with a range of possibly 5 

 to 7 per cent figured as oleic acid. All such oil can be refined as 

 follows : 



The oil should first be heated to about 85° C. and treated with caustic-soda solution 

 approximately 16° Baume. With the temperature maintained at this point the oil 

 and alkali are agitated gently to insure intimate contact, whereupon agitation is with- 

 drawn and the aqueous soapy layer allowed to separate as much as it will. It is then 

 drawn off. The oil is then heated to around 95° C. and sprayed with successive por- 

 tions of boiling-hot water (preferably brine) with thorough agitation. Agitation that 

 is too violent produces a troublesome emulsion, which can only be broken with 

 difficulty and by long heating or sweating out. If, however, the hot oil is given 

 comparatively mild agitation over the layer of hot water which has settled to the bot- 



