CASTOR OIL (so called from its fancied resemblance to castoremn). A fixed oil obtained from the seeds of /Wein us roni 01 11 nis (Linntn which is cultivated in India. In extracting the oil, the seeds are first bruised between rol lers. and then pressed in hempen bags under a hy draulic or screw press. The best va ricty of oil is thus obtained by pressure in the cold. and is known as cold-drawn castor oil; but if the bruised and pressed seeds be afterwards steamed or heated, and again pressed, a second quality of oil is obtained, which is apt to become par tially solid or frozen in cold weather. In either case the crude oil is heated with water to 2 I 2° 100° C.), which coagulates and separates the albumen and other impurities. Exposure to the sun's light bleaches the oil, and this proc ess is resorted to on a large scale. When pure and cold-drawn, castor oil is of a light-yellow color: but when of an inferior quality, it has a greenish. and occasionally a brownish, tinge. It is somewhat thick and viscid. Its specific gravity is high for an oil, being about .960. It is miscible with alcohol and ether. Reduced to a temperature of — 1.i° C. it becomes solid; exposed to the air, it very slowly becomes ran cid, then dry and hard, and serves as a connect ing link between the drying and non-drying oils. It has a nauseous smell, and an acrid, disagree able, and sickening taste, which may be over come by the addition of a little magnesia. The
principal acid present in it is ricinolcie acid, which is allied to oleic acid. It also contains palmitin, stearin, myristin, and an acrid principle.
Castor oil is largely used in medicine and the arts. As a simple purgative it acts in about live hours and empties the large intes tines. Its secondary effect is sedative and slightly constipating. It is not suited for eon tinned or repeated use. hut, should be in an emergency, or occasionally, for a single result. It is very useful in diarrInra due to eating indigestible or irritative substances, in the constipation of alcoholism, as well as of pregnaney, and in in fla mina tory diseases of the kidneys or of the generative organs. It may be administered in orange-juice, or flavored with oil of hitter almonds, or it mat' be given in cof fee or in soda-water. Pharmacists dispense it in soft, elastic capsules of gelatin, thus obvi ating the disagreeable smell and taste.
The adulterations of castor oil may he vari ous. Several of the fixed oils, including lard, may he employed. The best test of its purity is its complete solubility in its own volume of 1(.01101, a test which other fixed oils do not stand. Croton oil is occasionally added to increase the purgative powers of the oil.