CASTOR OIL (Oleum ricini), the fixed oil expressed from the seeds of Ruinus cons munis, of the family Euphorbiacea'. The oil is obtained from the seeds by various processes. The seeds are sometimes boiled and the oil skimmed from the water, or the oil may be taken up by solvents, such as alcohol, ether, etc. In the large manufacturing pharmacy houses in the United States the seeds are first warmed slightly and then passed between rollers, or other forms of pressure apparatus. The oil is collected and decanted, or mixed with boiling water and purified. The average yield of high grade oil is from 40 to 50 per cent in weight. Care must be exercised in the amount of heat ing of the seeds, else a very active and acrid tax-albumin, ricin, which is present in the seed coat, is added to the oil. This tends to render the oil very griping in its action. Unscrupulous manufacturers have been known to add small quantities of ricin to adulterated oil. Seconds, or sorts, are inferior qualities of oil.
When fresh and pure castor oil should be a clear, colorless, viscid oil, with a faint, mild odor, a bland and unpleasant taste. Its specific gravity should be .950-.970 at 60° F. It should be soluble in equal parts of alcohol, in all pro portions of absolute alcohol, or in glacial acetic acid, and tested to exclude other mixed oils; is soluble at 60° F. in three times its volume of a
mixture of 19 parts of alcohol and one part of water. This test will detect an admixture of over 5 per cent of other oils. Castor oil con geals at 15° F. The chemical structure shows castor oil to be composed almost entirely of ricinoleic acid, C=11,402. It also contains pal mitin, stearin, myristin and an acid prin ciple. This is broken up in the intestines by saponification, and sets free the active agent of the drug's action. Castor oil is a reli able cathartic. It empties the bowel com pletely, largely by its stimulating intestinal peristalsis, and is probably the best cathartic for children with overloaded intestines. In intestinal fermentation and putrefaction ac companied by diarrhoea, it is excellent. It causes a number of loose, not very watery movements, attended with mild griping. There is a tendency to constipation following its use; hence, it is not of service in habitual consti pation. As it is extremely disagreeable for many, its taste may be disguised by orange peel, or best in some aromatic frothy or carbonated mixture, as in coffee, soda water, or in gelatin capsule form. From a teaspoonful to a table spoonful is the usual dose.