2 BULLETIN 867, U. S. DEPARTMENT OF AGRICULTURE. 



brown to black. The beans vary in weight from O.lOgm. to 1.22 gm., 

 and in size from 7.5 mm. long by 50 mm. wide by 4.5 mm. thick to 

 23 mm. by 15 mm. by 8 mm., respectively. One cubic foot of beans of 

 average size weighs about 37 pounds. 



An analysis of a commercial sample of castor beans shows that 

 the whole bean consists of 35 per cent of seed coat and 65 per cent of 

 kernel, the oil content of these two parts being 10 and 62.9 per cent, 

 respectively. 



Analyses of 37 samples of castor beans imported from India, China, 

 the West Indies, and South America show a range of oil content, 

 determined by ether extraction, from 38.39 to 55.55 per cent, with 

 an average value of 48.75 per cent. " Similar assay of 50 samples of 

 beans from the first American crop from imported seed in 1918 

 shows a range of 42.13 to 58.57 per cent, averaging 48.16 per cent. 

 With present milling practices there is obtained about 15.6 pounds 

 of No. 1 oil per 46-pound. bushel, 4.1 pounds of No. 3 oil, and 25.5 

 pounds of pomace, with a shrinkage per bushel of about 0.8 pound. 



Castor beans contain a poisonous principle which renders them 

 extremely dangerous when eaten. Also picking off the seed coats 

 with the fingers has been followed by inflammation and soreness under 

 the finger nails. Persons who have weak eyes or who are subject 

 to hay fever may suffer serious inconvenience, to say the least, fol- 

 lowing exposure to the dust from ground dried castor pomace 



The common belief that the coloring matter occurring in castor oil 

 extracted by the solvent process is introduced through the so-called 

 germ has not been borne out by experiments. On the contrary, the 

 color seems to be mostly derived from the seed coats. It is observed 

 that decorticated kernels yield a light-colored oil when extracted 

 by volatile solvents, while the whole bean or the seed coats alone 

 yield progressively more highly colored oils. But the coloring matter 

 is evidently not a single simple substance, for upon extraction with 

 different solvents different colors are obtained. Benzol gives a green- 

 colored oil, gasoline a yellowish oil, while methyl ethyl ketone, ace- 

 tone, ethyl alcohol, and methyl acetate all yield a red-colored oil 

 which slowly turns to dark brown on exposure to the air. 



Castor beans also contain the enzym lipase, which is extremely 

 active in hydrolyzing the oil to glycerin and free fatty acid. This 

 action does not occur so long as the seed coat remains intact and 

 protects the kernel from exposure to the air, but when the seed coat 

 is broken the enzym quickly begins its hydrolytic action. Since 

 broken and damaged beans when crushed yield a highly colored 

 acid oil, care must be exercised in hulling and shipping to avoid 

 breaking the seed coats. 



Another factor contributing to the high acidity of castor oil is what 

 are known as black beans. These are rancid beans, the kernels of 



