Castor Oil is obtained from the seeds or 'beans' of the plant Ricinus communis, which grows wild in most tropical and sub-tropical regions, but is cultivated mainly in Brazil and India. The seeds, containing 40-50 per cent of oil, are first 'cold pressed' in hydraulic presses to remove a portion of the oil for medicinal purposes, and the cake residue is solvent-extracted to recover most of the remaining oil for a variety of industrial uses.
Castor oil is particularly suitable as a laxative, being broken down in the intestine to ricinoleic acid which has a strong irritant purgative action. Apart from its medicinal use, castor oil is a raw material from which is derived sodium ricinoleate, used for treatment of gum troubles. It is used industrially for soap-making, as a high-temperature lubricant, in fluids for hydraulic systems, in the manufacture of plastics, in the textile industry, and it is dehydrated by heating with a catalyst to produce a drying oil for use in the preparation of such products as paints, varnishes, inks, linoleum and oil-cloth.