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a fatty vegetable oil obtained from the seeds of the castor-oil plant. It is one of the nondrying liquid oils; it contains 3–9 percent oleic acid, 3–5 percent linoleic acid, and at least 80 percent ricinoleic acid. The high content of the ricinoleic acid is responsible for the properties of castor oil: high kinematic viscosity (more than X 10 -6 m2/sec at 50°C) and density (950–974 kg/m3 at 15°C). Unlike other fatty vegetable oils, it is readily soluble in alcohol but poorly soluble in benzine.
Castor oil is widely known for its medicinal properties. The ancient Egyptians used it to make all kinds of ointments and balms. It is best known for its use as a laxative. Combined with quinine, Pituitrin, pachycarpinum, and other substances, it is used to induce labor. Ointments and balms containing castor oil are used in the treatment of burns and ulcers, softening of the skin, and so forth. Castor oil has also found application in some branches of industry—for example, soap manufacture and oil boiling. Castor oil is a high-grade lubricant.