Derivation.—Castor oil is expressed from the seeds of a plant (Ricinus communis) which grows in the East Indies and Africa in the character of a tree and rises sometimes thirty or forty feet. It also grows in the temperate latitudes of North America and Europe.

Properties.—Pure castor oil is a thick, viscid, colorless liquid, with little or no odor and a mild though somewhat nauseous taste.

Action and Uses.—Good castor oil is a mild and speedy cathartic, usually operating within four to five hours with little griping or uneasiness, and evacuating the contents of the bowels without much increasing the alvine secretions. Hence it is particularly applicable to constipation from collections of abnormally hard faeces, and to cases in which irritating substances have been swallowed or irritating substances have accumulated in the bowels. From its mildness it is also especially adapted to diseases of the bowels, as colic, indigestion, diarrhoea, dysentery and enteritis. It is also indicated in overloaded bowels in pregnancy combined with anodynes and antispasmodics to prevent griping. Castor oil in two or three ounce doses conjoined with gruel and five or six drops of oil of peppermint is suitable for foals and calves affected with gastro-intestinal disorders. Castor oil is specially applicable in canine practice, to evacuate the bowels, and in irritated conditions of the digestive tract, in ounce doses mixed with equal parts of glycerine and adding two or three drops of oil of wintergreen.

Castor oil may be given to horses in sixteen ounce doses conjoined with oil of peppermint, twenty drops, or tincture opium, one ounce and fluidextract of belladonna, one to two drachms, flour gruel, etc.

Castor oil in one to two drachm doses is especially valuable for poultry.

Castor oil is used with equal success in the treatment of gastro-intestinal disorders of cattle, sheep and pigs.

Dose.—Horses and cattle, 12 to 16 oz.; sheep and pigs, 2 to 6 oz.; dogs and cats, ¹/₂ to 2 oz.; poultry, ¹/₂ to 2 dr.