Oleum Myrciae (U. S. P.)—Oil of Myrcia.
Related entry: Spiritus Myrciae (U. S. P.)—Spirit of Myrcia
"A volatile oil distilled from the leaves of Myrcia acris, De Candolle (Nat. Ord.—Myrtaceae). It should be kept in well-stoppered bottles, in a cool place, protected from light"—(U. S. P.).
SYNONYM: Oil of bay.
Botanical Source and History.—The tree producing the leaves which yield oil of bay, is indigenous to Venezuela and the West Indies, where it is known as the Wild cinnamon, Bayberry, and Wild clove tree. Its branches are 4-angled, and support broad-ovate, almost obtuse, short-petiolate, strongly-veined, entire, leathery leaves. These are dotted with pellucid oil-glands, and when bruised give off a pleasant, clove-like aroma. The flowers are small and reddish, and the fruit is a smooth, subglobular berry. Oil of bay and Spirit of bay, or Bay rum, are distilled from this plant.
Preparation.—This oil is obtained partly in the islands from the fresh leaves, but mostly in the United States, from the dried leaves, by distilling them with water, or by means of steam. An oil lighter than water first distills over, followed by another heavier than water. The commercial oil consists of a combination of these two fractions.
Description and Tests.—"A yellow or brownish-yellow liquid, having an aromatic and somewhat clove-like odor, and a pungent, spicy taste. Specific gravity, 0.975 to 0.990 at 15° C. (59° F.). With an equal volume of alcohol, glacial acetic acid, or carbon disulphide, it yields slightly turbid solutions. The alcoholic solution is slightly acid to litmus paper. When mixed with an equal volume of a concentrated solution of sodium hydrate, it forms a semisolid mass. If 2 drops of the oil be dissolved in 4 Cc. of alcohol, and a drop of ferric chloride T.S. be added, a light-green color will be produced; and if the same test be made with a drop of diluted ferric chloride T.S., prepared by diluting the test-solution with four times its volume of water, a light-bluish coloration will be produced, which soon disappears. If to 3 drops of the oil, contained in a small test-tube, 3 drops of concentrated sulphuric acid be added, and, after the tube has been corked, the mixture be allowed to stand for ½ hour, a resinous mass will be obtained. On adding to this mass 4 Cc. of diluted alcohol, vigorously shaking the mixture, and gradually heating to the boiling point, the liquid should remain nearly colorless, and should not acquire a red or purplish-red color (distinction from oil of pimenta and oil of cloves). If 1 Cc. of the oil be shaken with 20 Cc. of hot water, the water should not give more than a scarcely perceptible acid reaction with litmus paper. If, after cooling, the liquid be passed through a wet filter, the clear filtrate should produce, with a drop of ferric chloride T.S., only a transient grayish-green, but not a blue or violet color (absence of carbolic acid)"—(U. S. P.). The test for distinguishing between this oil and oil of pimenta, above given, is regarded by Schimmel & Co. (Prof. F. B. Power, Essential Oils, 1894) as unreliable.
Chemical Composition.—The following substances, arranged in the order of their relative proportions, have been ascertained to occur in oil of bay: (1) Eugenol, first observed in this oil by Prof. Markoe (1877); (2) myrcen (C10H16), a liquid, unsaturated, open-chain hydrocarbon (olefine) of a characteristic odor, specific gravity 0.802, and convertible by hydration into linalool; (3) chavicol (C9H10O); (4) methyl-eugenol; (5) methyl-chavicol; (6) 1-phellandrene; (7) citral. No pinene is present, hence oil of turpentine may easily be recognized if present as an adulterant (Gildemeister and Hoffmann, Die Aetherischen Oele, p. 669).
Action, Medical Uses, and Dosage.—This oil is chiefly employed in perfumes, and is a constituent of Spiritus Myrciae, or Bay rum.