paut ii. Materia Medica. — Ricini semina, oleum. 479

East and West Indies, South America, and Africa. 1 It is ofvery quick growth, and sometimes attains to the height of six-teen feet.* The stem is round, thick, jointed, furrowed, glau-cous in the lower part, but of a purplish red colour towards thetop: the leaves are petiolate and subpeltate, large, deeply di-vided into seven pointed serrated lobes, and of a blueish greencolour: the calyx of the male flower is composed of five ova],pointed, purplish segments, inclosing many long stamens unitedat the base ; the female is at the upper part of the spike, andis composed of a three-cleft, reddish calyx : the styles are three,slender, and forked at the apex : the capsule is a trilocular nut,covered with rough spines, and bursting elastically to expel theseeds, which are generally three, and of an oblong flat figure,and white colour.

The oil, which is more frequently used than the seeds, isobtained from the seeds both by coction and expression. Theformer method was generally used till lately; and was perform-ed by tying up the seeds, previously decorticated and bruisedin a bag, -which was suspended in boiling water till all the oilwas extracted and rose to the surface, when it was skimmed off.This mode of preparation is still preferred by many of theWest Indian practitioners; but as the oil is apt to get soonrancid when thus prepared, it is now obtained both at homeand abroad, by subjecting the seeds to the press, in the samemanner as almonds to procure almond oil. The oil obtainedis equal to one-fourth of the weight of the seeds employed. It isoften adulterated with olive oil, linseed oil, and poppy oil, which,however, may be readily detected by adding an equal quantityof alcohol sp. gr. 820 to any given quantity of the suspectedoil; if it be pure, a uniform solution will take place, which willnot happen should it be adulterated: and the same will be thecase, if a weaker spirit be employed, by the addition of camphor.

Qualities. — Good expressed castor oil is nearly inodorousand insipid: but the best leaves a slight sensation of acrimonyin the throat after it is swallowed. It is thick, viscid, transpa-rent, and colourless, or of a very pale straw colour; that whichis obtained by coction has a brownish hue; and both kinds,when they become rancid, thicken, deepen in colour to reddishbrown, and acquire a hot, very nauseous taste. It has all thechemical characters of the other expressed oils, except that itis very soluble in alcohol and also in sulphuric ether.

Medical properties and uses. — The seeds are drastic cathar-tics, but are scarcely ever ordered. The oil is mildly purgative,

1 It was first cultivated in Britain in 1562.

a It has been asserted that this plant is in some places perennial, becoming alarge tree. Willdenow, however, says, " Planta semper annua, nunquam fruticosavel arborea, nee in calidissimis terra; plagis lignescit." Socc. Plant, iv. 564,