Oleum Origani.—Oil of Origanum.

Related entry: Origanum.—Origanum

SYNONYM: Oil of wild marjoram.

Preparation and Description.—This oil is produced from the Origanum vulgare, by distillation of the plant with water. The yield referred to dried herb is 0.15 to 0.4 percent (Schimmel &Co.). It is of a yellowish or reddish-yellow color, of a peculiar, agreeable, balsamic odor, and a warm, very pungent taste. Its specific gravity ranges from 0.87 to 0.91. It is imported from Europe, and frequently contains oil of turpentine. Very little true oil of origanum is met with in this country; that generally sold for it is imported from France.

Chemical Composition.—A camphor-like stearopten has been observed in this oil by Kane (1839). Two phenols, one being carvacrol, were found in the oil by Jahns (1880) in small quantity, not exceeding 0.1 per cent. The bulk of the oil is probably composed of terpenes (C10H16). Its chemical examination is incomplete.

Action, Medical Uses, and Dosage.—Oil of origanum is stimulant and rubefacient, and is chiefly employed in the form of liniment as an application to various parts suffering from painful affections. As with many other essential oils, it affords relief in toothache upon being applied to the decayed tooth by means of lint or cotton. It is very seldom administered internally.

Related Oils. Ɣ OLEUM MAJORANAE. The Oil of sweet marjoram, obtained by distillation of the Origanum majorana, Linné, is a pale yellow or greenish-yellow oil with the strong odor and taste of sweet marjoram, and on standing deposits a camphor. Its specific gravity is 0.890 to 0.91. Optical rotation +17° 10' (Schimmel & Co.). According to W. Biltz (1898), this oil contains 40 per cent of terpenes, chiefly terpinene, and in addition, dextro-terpineol, partly in the form of ester. It is employed as a medicine and as a perfume for soaps. It is seldom used in the United States.

OLEUM ORIGANI CRETICI, Cretian oil of origanum.—This herb is distilled from several species of Origanum, as O. creticum, Linné; O. hirsutum, Link; O. macrostachyum, Link, and O. megastachyum, Link. A golden-yellow oil when fresh, becoming yellowish or brownish with age. It has an aromatic, penetrating, thyme-like odor. Specific gravity, 0.960 to 0.980 (Power). The Trieste commercial variety, probably derived from O. hirsutum, Link, contains, according to Jahns (1879), carvacrol (isopropyl ortho-cresol, C6H3.CH3.OH.C3H7), a colorless, thick, liquid phenol, solidifying in the cold. Good origanum oil should contain from 60 to 85 percent. Jahns furthermore found 0.2 percent of a second phenol and a large amount of cymol. Smyrna origanum oil (from the herb of Origanum smyrnaeum, Linné) also contains cymol, but less carvacrol (25 to 60 per cent), and contains in addition l-linalool (Gildemeister, Archiv der Pharm., 1895, p. 182). Origanum oil forms a clear solution with 3 parts of 70 per cent alcohol. For microscopical purposes the oil should be pale-yellowish and kept in well-filled and closely-stopped bottles, placed in a dark situation (Power, Essential Oils).

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.