CASTOR-OIL INDUSTRY. 9 



not yet bought on the above-suggested basis, but sooner or later such 

 will doubtless be the practice. The only objection to this seems to 

 be the desire of those interested not to change present methods, 

 fearing that complications would be added to transactions unfavor- 

 able to growth in trade. 



MANUFACTURE OF CASTOR OIL. 



CLEANING. 



The castor beans of commerce come mixed with such amounts of 

 trash that it is absolutely necessary to remove this at the earliest 

 stages of the operation. An ordinary grain cleaner is used, with 

 special perforations in the screens for castor beans. These cleaners 

 are a combination of screens and fans, which remove the straw, 

 hulls, and dirt in successive operations of sieving and fanning and 

 deliver the cleaned beans. Such machines vary greatly in size, 

 with attendant capacities of 30 to 1,200 bushels of beans per hour. 



DECORTICATION. 



Owing to the peculiar structure of the castor bean, its milling 

 technology has developed along lines peculiar to itself. Several 

 special machines have been built to decorticate castor beans. The 

 process depends on cracking the brittle seed coats between rolls set 

 so as to exert a cracking pressure rather than a crushing, and mangling 

 one. The beans with their broken seed coats are dropped on a 

 shaking screen which serves to shake the kernels out of the adhering 

 seed coats and otherwise loosen up the mass. As the charge falls 

 over the end of the shaker, a current of air blows out the seed coats, 

 while the kernels fall into a hopper below. 



It is very difficult to make a perfect separation of hulls from kernels 

 by the mechanical decortication of castor beans as they are usually 

 delivered from the warehouse. One of the factors contributing to 

 this difficulty is the irregularity in the size of the beans, the small 

 ones dropping between the rolls unaffected, while the large ones are 

 crushed. This requires a grading of the beans, which of course can 

 readily be done mechanically. 



Such decortication would be all the better effected if the beans 

 were given a preliminary drying, such as could easily be accomplished 

 in the heaters described later. With regard to the question of added 

 moisture for optimum pressing conditions, see under "Heating." 

 The advantages of decorticating consist in giving a somewhat lighter 

 colored oil and at the same time removing the constituents which 

 wear out the equipment. The literature persistently reports that 

 the Italians produce a very superior medicinal grade of oil, which is 

 practically tasteless, by pressing beans which have been decorticated 

 or dehulled and carefully picked over by hand to remove the bits of 

 adhering hull. On the other hand, the lack of sufficient fiber neces- 

 182601°— 20 2 



