CASTOR OIL, the fixed oil obtained from the Castor Oil Plant or Palma Christi, Ridnus communis, belonging to the Natural Order Euphorbiaceoe. The plant is a native of the East Indies, but it has been introduced, and is now cultivated in most tropical and in the warmer temperate countries. In size it varies from a shrubby plant to a tree of from 30 to 40 feet in height according to the climate in which it grows, being arborescent in tropical latitudes. On account of its very large beautiful palmate-peltate leaves, which measure as much as 2 feet in diameter, it is cultivated as an ornamental plant. In the south of England, with the habit of an annual, it ripens its seeds in favourable seasons; and it has been known to come to maturity as far north as Christiania in Norway. The fruit consists of a tricoccous capsule, covered externally with soft yielding prickles, and each cell develops a single seed. The seeds of the different cultivated varieties, of which there are a great number, differ much in size and in external markings; but average seeds are of an oval laterally compressed form, with their longest diameter about four lines. They have a shining, marble grey and brown, thick, leathery epidermis, within which is a thin dark-coloured brittle coat. The cotyledons readily separate, and show a large distinct leafy embryo. The oil is obtained from the seeds by two principal methods—expression and decoction,—the latter process being largely used in India, where the oil, on account of its cheapness and abundance, is extensively employed for illuminating as well as for other domestic and medicinal purposes. The oil exported from Calcutta to Europe, which is said to be “cold drawn and nearly tasteless,” is prepared by shelling and crushing the seeds between rollers. ...