Castor Oil

Collier's New Encyclopedia (1921)

a fixed oil obtained from the seeds of the castor oil plant. In extracting the oil the seeds are first bruised between heavy rollers and then pressed in hempen bags under a hydraulic or screw press. The best variety of oil is thus obtained by pressure in the cold, and is known as cold-drawn castor oil, but if the bruised and pressed seeds be afterward steamed or heated and again pressed, a second quality of oil is obtained, which is apt to become partially solid or frozen in cold weather. In either case the crude oil is heated with water to 212°, which coagulates, and separates the albumen and other impurities. Exposure to the sun's light bleaches the oil, and this process is resorted to on a large scale. When pure and cold-drawn, castor oil is of a light-yellowish color; but when of inferior quality it has a greenish and occasionally a brownish tinge. It is somewhat thick and viscid. Its sp. gr. is high for an oil, being about 960 (water being taken as 1,000). It is mixable with alcohol, or spirits of wine, and ether. It has a nauseous smell and an acrid, disagreeable taste, which may be overcome by the addition of a little magnesia. The principal acid in it is ricinoleic acid. Castor oil is one of the most convenient and mildest of purgative medicines. The sickness often produced by the disagreeable flavor of castor oil is by some obviated by floating the oil in hot coffee, which in a measure removes its nauseous qualities.