Oleum Carui, B.P. Oil of Caraway.
Oil of caraway (Oleum Cari, U.S.P.) is obtained by distillation from the freshly crushed fruit of caraway, Carum Carvi, Linn. (N.O. Umbelliferae), cultivated in England, Holland, Norway, and Eastern Prussia. It occurs as a colourless liquid, becoming yellow on keeping, having the characteristic odour of caraway, and a mild, spicy taste. Specific gravity, 0.907 (B.P., 0.910) to 0.920 (0.900 to 0.910 at 25°). Rotation, +70° to +82°. Exposure to the air causes the oil to become viscous and of a higher specific gravity, and so also with carvone, the chief constituent of the oil. If either, in such condition, be dissolved in an equal volume of alcohol, the addition of a few drops of very dilute solution of ferric chloride produces a reddish-violet colour, vanishing on the further addition of ferric chloride. No such reaction is given with the freshly distilled substance. Alcohol, which is sometimes used as an adulterant, should be specially looked for in testing the oil. Fractional distillation of the oil should yield not more than 25 per cent. below 185°, and at least 55 to 65 per cent. over 200°.
Sparingly soluble in alcohol (70 per cent.); yields a clear solution with 3 to 10 volumes of alcohol (80 per cent.), and with an equal volume of alcohol.
Constituents.—Carvone (carvol), C10H14O, an unsaturated ketone, is the chief constituent, and is present to the extent of 45 to 60 per cent. The only other important constituent of the oil is the terpene d-limonene, also called carvene, the specific gravity of which is 0.846, rotation about +107°, boiling-point, 175° to 176°. Carvacrol is said to be present in traces.
Actions and Uses.—Oil of caraway is an aromatic carminative to the gastro-intestinal tract, and is used in purgative pills to allay the tendency to griping. It may be administered on sugar to remove flatulent colic, and as Aqua Carui to children for the same purpose.
Dose.—¼ to 2 decimils (0.025 to 0.2 milliliters) (½ to 3 minims).
- Aqua Carui Concentrata, B.P.C.—CONCENTRATED CARAWAY WATER.
- One part of this solution corresponds to 40 parts of caraway water.