RIVINUS COM3ILVNIS, the castor-oil plant, known from very ancient times both to the Egyptian, and also to the Greeks. According to Ilerodotus (iL 9I), the Egyptians called the oil of the tillicyprion (oslaudrzpor) by the name (efet), The Greeks also called it Croton (spin's), a name bestowed by modern botanists on a closely allied genus of euphorbiaceoua plantn, one species of which yields the purgative oil designated Croton oil, or Oleuni Tiglii. The native country of the Ric-inns communis is unknown, though it is conjectured to be originally from liarhar7. Like all plants which have been long in cnItivation, numerous varieties of it are met with, differing not only In colour and the peculiar pruinose condition of the stem, but in stature and duration. In warns countries it 14 ligneous and perennial ; in cold, annual and herbaceous. The entire plant is possessed of active properties, but the oil extracted from the seeds is only employed in Europe : the ancients administered the seeds entire, but their variable action, occasionally even producing fatal effects, led to their disuse, and the oil Is of comparatively recent introduction. The seeds, of which three are found in each capsule, are about the size of a small bean, obtuse at both ends, surface smooth, shining, and beautifully marbled. The skin consists' of three tunics—let, an outer brittle pellicle ; 2nd, • hard testa consisting of two dissimilar layers, tho external thick, dark brown, fanned of trionverse radiating cella ; the internal thinner, paler, and formed of vertical cells; 3rd, a membrane investing tau nucleus or kernel. " The nucleus consists of oily albumen, and an embryo, the cotyledons of which are membranous or foliaceous." The outer shell is devoid of taste; in the inner coat the acrimony or active principle resides, according to IKerbach; while others assert the embryo to be the seat of the purgative principle; and even Humboldt and Bancroft state that If this part be excised. the seeds may be eaten, with impunity, or the oil thereafter expressed is as mild as olive-oiL Various procedures have been adopted to extract the oil, and these have much influence on its qualities in respect of colour, acridity, and freedom from rancidity : there are also effects which result from the greater or less maturity of the seeds, the peculiar variety of the plant from which they have been obtained, and the occasionally accidental, but more frequently intentional admixture of other seeds, before the different processes of extraction have been begun. Beth in India and America, whence the first supplies were brought, much heat was employed, and during the application of this agent a volatile principle was either liberated, or more probably formed, which was so irritating as to require the workmen to protect their faces by masks. Even in the present day some heat is used to
obtain what is termed the cold-drawn castor-oil, but It is quite unnecessary, and should always be avoided.
According to Sir Whitelaw Ainslie (' 3lateria Indica,' vol. i. p. 256), the following is the plan puraual in the East Indic. :—" Take five seers of the small castor-oil nuts, and soak them for one night in cold water ; next morning strain this water off and throw it away, and put the nets into a second quantity of fresh water, and boil them in it for two bourn; after which strain the water off and throw it away, an in the first instance : the nuts then are to be dried in the sun on a mat for three days ; st the end of which time they aro to be well bruised in a mortar : old to the nuts thus bruised ten measure. el water, and met the whole on the fire to boil, Liking care to keep continually stirring the contents of the pot until all the oil appears at the top, when it is to be carefully strained off and bottled for use. The quantity of nuts mentioned in this formula ought to yield about one quart bottle of Gil." The processes used in the United States and the West Indies are both objectionable, from employing not only haat but water, which kat promotes the rancidity of the oil. The acrid property and the rancidity are owing to different causes, the former being always in proportion to the freshness of the oil, the latter to the imperfection of the means used in extracting it, or to its age. The plan adopted in France is the best ; it is as follows :—The fresh seeds are bruised, and then put into a cold press (some persons improperly heat the plates of the press). The oil expressed is allowed to stand some time to permit the albumen, mucilage, and other matters to subside, or it is filtered to separate them more rapidly. (' Journal de Pharmacie; tom. v. pp. 207, 506.) The produce is equal to about a third of the seeds employed, and the oil possesses all its natural qualities. The American process yields only 25 per cent. of oil. In the French West Indian Islands, a peculiar 'variety of lticinus, called R. rubes more active, is used, which yields an oil called carapat, or karahat, but this is violent and unpleasant, and must not be or substituted the fine oil procured in France. Both the French and Italian oils are much weaker than oil procured from tropical countries. Another mode of obtaining the oil is to macerate the bruised seeds in cold alcohol, by which six ounces of oil are procured from every pound of seeds. ('Journal de Pharmacie; viii. 475.) The expense of this process is the objection to its general employment.