Oleum Juniperi (U. S. P.)—Oil of Juniper.
A volatile oil distilled from the fruit of Juniperus communis, Linné (Nat. Ord.—Coniferae). It should be kept in well-stoppered bottles, in a cool place, protected from light"—(U.S. P.).
SYNONYMS: Oleum fructus juniperi, Oleum baccae juniperi, Oil of juniper-berries.
Preparation and Description.—Oil of juniper is procured from the bruised berries by distillation with water. The full-grown, green fruit yields more oil than the ripe, as in the process of ripening the oil becomes converted into resin. Schimmel & Co. (Report, April, 1897) obtained a yield varying from 0.6 per cent in east Prussian to 1.5 per cent in Italian berries. Oil of juniper is "a colorless or faintly greenish-yellow liquid, becoming darker and thicker by age and exposure to air, having the characteristic odor of juniper, and a warm, aromatic, somewhat terebinthinate and bitterish taste. Specific gravity, 0.850 to 0.890 at 15° C. (59° F.). Soluble in about four times its volume of alcohol, forming a somewhat turbid liquid, which is neutral or slightly acid to litmus paper. Also soluble in an equal volume of carbon disulphide"—(U. S. P.). The optical rotation of oil of juniper is mostly left-handed (to -18°), sometimes right-handed, rarely inactive. As a rule, the oil is soluble in about 8 to 10 parts of alcohol of 90 per cent by volume; age diminishes its solubility in alcohol.
Chemical Composition.—Pinene is contained in the fraction of the oil boiling from 155° to 162° C. (311° to 323.6° F.); cadinene in the fraction 260° to 275° C. (500° to 527° F.); the intermediary fractions, containing esters, have not been fully analyzed, but contain the characteristic aroma of the oil. The aroma can not be due to an ester, because it outlasts saponification. Juniper-camphor, frequently observed by older chemists, forms crystalline deposits in the higher fractions of the oil when exposed to cold. One such deposit of needles, upon purification, melted at 165° to 166° C. (329° to 330.8° F.) (Gildemeister and Hoffmann, Die Aetherischen Oele, p. 350).
Action, Medical Uses, and Dosage.—Oil of juniper is a stimulant diuretic, and is employed to arrest chronic mucous discharges, especially from the urethra. It may also be used as a diuretic with other agents in cases of dropsy. Locally, it reddens the skin, and may vesicate. The dose is from 5 to 15 or 20 drops. The peculiar taste and diuretic property of Holland gin is owing to the presence of this oil.