570 EUPHORBIACE^. 



them, act much more strongly than a corresponding quantity of oil. 

 Castor oil, extracted by absolute alcohol or by bisulphide of carbon, 

 likewise purges much more vehemently than the pressed oil. 



The castor oil of commerce has a sp. gr. of about 0'96, usually a 

 pale yellow tint, a viscid consistence, and a very slight yet rather 

 mawkish odour and taste. Exposed to cold, it does not in general 

 entirely solidify until the temperature reaches - 18° C. In thin layers 

 it dries up to varnish-like film. 



Castor oil is distinguished by its power of mixing in all proportions 

 with glacial acetic acid or absolute alcohol. It is even soluble in four 

 parts of spirit of wine ("838) at 15° C, and mixes without turbidity 

 Avith an equal weight of the same solvent at 25° C. The commercial 

 varieties of the oil however differ considerably in these as well as in 

 some other respects. 



The optical properties of the oil demand further investigation, as 

 we have found that some samples deviate the ray of polarized light to 

 the right and others to the left. 



By saponification castor oil yields several fatty acids, one of which 

 appears to be Palmitic Acid. The prevailing acid (peculiar to the oil) 

 is Ricinoleic Acid, C'^H**0^; it is solid below 0° C, does not solidifj' in 

 contact with the air by absorption of oxygen, and is not homologous 

 with oleic or linoleic acid, neither of which is found in castor oil. 

 Castor oil is nevertheless thickened if 6 parts of it are warmed with 

 1 part of starch and 5 of nitric acid (sp. gr. 1"25), Ricinelaidin being 

 thus formed. From this Ricineldidic Acid may easily be obtained in 

 brilliant crystals. 



As to the albuminoid matter of the seed, Fleury (1865) obtained 

 3"23 per cent, of nitrogen which would answer to about 20 per cent, of 

 such substances. The same chemist further extracted 46 6 per cent, of 

 fixed oil, 2-2 of sugar and mucilage, besides 18 per cent, of cellulose. 



Tuson in 1864, by exhausting castor oil seeds with boiling water, 

 obtained from them an alkaloid which he named Micinine. He states 

 that it crystallizes in rectangular prisms and tables, which when heated 

 fuse, and upon cooling solidify as a crystalline mass ; the crystals may 

 even be sublimed. Ricinine dissolves readily in water or alcohol, less 

 freely in ether or benzol. With mercuric chloride, it combines to form 

 tufts of silkj'- crystals, soluble in water or alcohol. Werner (1869) on 

 repeating Tuson's process on SO lb. of Italian castor oil seeds, also ob- 

 tained a crop of crystals, which in appearance and solubility had many 

 of the characters ascribed to ricinine, but differed in the essential point 

 that when incinerated they left a residuum of magnesia. Werner 

 regarded them as the magnesium salt of a new acid. Tuson^ repudiates 

 the suspicion that ricinine may be identical with Werner's magnesium 

 compound. E. S. Wayne of Cincinnati (1874) found in the leaves of 

 Ricinus a substance apparently identical with Tuson's ricinine; but 

 he considers that it has no claim to be called an alkaloid. 



The testa of castor oil seeds afforded us 107 per cent, of ash, one 

 tenth of which we found to consist of silica. The ash of the kernel 

 previously dried at 100 C. amounts to only 3*5 per cent. 



Production and Commerce — Castor oil is most extensively pro- 

 1 Chemical News, xxii. (1870) 229. 



