or Palma Christi, in botany: A genus of the monodelphia order, belonging to the monoecia class of plants; and in the natural method ranking under the 38th order, Tricoceae. The male calyx is quinquepartite; there is no corolla; the stamens numerous. The female calyx is tripartite; there is no corolla, but three bifid styles, with a trilocular capsule, and a single seed. There are three species, of which the most remarkable is the communis, or common palma Christi. This tree is of speedy growth, as in one year it arrives at its full height, which seldom exceeds 20 feet. The trunk is subligneous; the pith is large; the leaves broad and palmated; the flower spike is simple, and thickly set with yellow blossoms in the shape of a cone; the capsules are triangular and prickly, containing three smooth gray mottled seeds. When the bunches begin to turn black, they are gathered, dried in the sun, and the seeds picked out. They are afterwards put up for use as wanted, or for exportation.

Castor oil is obtained either by expression or by decoction. The first method is practised in England; the latter in Jamaica. It is common first to parch the nuts or seeds in an iron pot over the fire; but this gives the oil an empyreumatic taste, smell, and colour; and it is best prepared in this manner: A large iron pot or boiler is first prepared, and half filled with water. The nuts are then beaten in parcels in deep wooden mortars, and after a quantity is beaten it is thrown into the iron vessel. The fire is then lighted, and the liquor is gently boiled for two hours, and kept constantly stirred. About this time the oil begins to separate, and swims on the top, mixed with a white froth, and is skimmed off till no more rises. The skimmings are heated in a small iron pot, and strained through a cloth. When cold, it is put up in jars or bottles for use.

Castor oil, thus made, is clear and well flavoured, and if put into proper bottles will keep sweet for years. The expressed castor oil soon turns rancid, because the mucilaginous and acid parts of the nut are squeezed out with the oil. On this account the preference is given to well prepared oil by decoction. An English gallon of the seeds yield about two pounds of oil, which is a great proportion.

Before the disturbances in America, the planters imported train oil for lamps and other purposes about sugar works. It is now found that the castor oil can be procured as cheap as the fish oil of America: it burns clearer, and has not any offensive smell. This oil, too, is fit for all the purposes of the painter, or for the apothecary in ointments and plasters. As a medicine, it purges without stimulus, and is so mild as to be given to infants soon after birth, to purge off the meconium. All oils are noxious to insects, but the castor oil kills and expels them. It is generally given as a purge after using the cabbage bark some days. In constipation and belly-ach this oil is used with remarkable success. It fits well on the stomach, allays the spasm, and brings about a plentiful evacuation by stool, especially if at the same time fomentations, or the warm bath, are used.—Belly-ach is at present less frequent in Jamaica than formerly, owing to several causes. The inhabitants, in general, live better, and drink better liquors; but the excessive drinking of new rum still makes it frequent amongst soldiers, sailors, and the lower order of white people. It has been known to happen too from visceral obstructions after intermittents, or marsh fevers, in Jamaica.

The ricinus Americanus grows as tall as a little tree, and is so beautiful that Millar says it deserves a place in every curious garden, and he planted it himself at Cheltenham. It expands into many branches; the leaves are sometimes two feet in diameter, and the stem as large as a middle-sized broom staff; towards the top of the branch it has a cluter of flowers, something resembling a bunch of grapes; the flowers are small and flaminoius, but on the body of the plant grow bunches of rough triangular husks, each containing three speckled seeds, generally somewhat less than horse beans; the shell is brittle, and contains white kernels of a sweet, oily, and nauseous taste. From this kernel the oil is extracted, and if the medicine should become officinal, the seeds may be imported at a reasonable rate, as the plant grows wild and in great plenty in all the British and French American islands. See Olrum Palmae Christi. Of the ricinus communis there are a great many varieties; all of them fine majestic plants, annual, or at most biennial, in this country; but in their native soil they are said to be perennial both in root and stem. They are propagated by seeds sown on a hot-bed, and require the same treatment as other tender exotics.

RICOCHETS, in medicine. See there, n° 347.