Oleum Rosmarini, B.P. Oil of Rosemary.
Oil of rosemary (Oleum Anthos) is obtained by distillation from the flowering tops of rosemary, Rosmarinus officinalis Linn. (N.O. Labiatae), an evergreen shrub, native of Southern Europe, growing abundantly on dry rocky hills in the Mediterranean regions. Most of the oil is imported from the South of France and the Dalmatian Islands, but that distilled in Britain is superior to the imported oil. Oleum Rosmarini, U.S.P., should yield not less than 2.5 per cent. of ester calculated as bornyl acetate, and not less than to per cent. of total borneol. Oil of rosemary occurs as a colourless, pale yellow, or slightly greenish-yellow liquid, having the characteristic pungent odour of rosemary and a warm, bitter, camphoraceous taste. Specific gravity, 0.895 to 0.920 (B.P., 0.900 to 0.915), (0.890 to 0.915 at 25°). Rotation, usually dextrorotatory, +1° to +12°, but English and Spanish oils are frequently slightly laevorotatory. Saponification value, 12 to 20. The chief adulterants of oil of rosemary are oil of turpentine and petroleum, both of which are much less soluble in alcohol than is oil of rosemary. Petroleum would be shown on evaporating the oil on a water-bath; the pure oil volatilises, leaving only a slight resinous residue, whereas the petroleum would remain. Fractions of camphor oil and alcohol have also been used to adulterate, but these affect the gravity, while the presence of alcohol may also be detected by drying the oil over fused calcium chloride and adding a crystal of magenta, which will dissolve and colour the oil pink if alcohol be present, but is insoluble in pure oil of rosemary.
Soluble in alcohol in all proportions, and in 80 per cent. alcohol (1 in 5 to 10).
Constituents.—The chief constituents of the oil are borneol, 10 to 16 per cent.; bornyl acetate and other esters, 2 to 5 per cent. Other constituents are camphor, cineol, pinene, and camphene.
Action and Uses.—Oil of rosemary has the carminative properties of other volatile oils. It is employed, principally as Spiritus Rosmarini, in hair lotions for its odour and for its supposed effect in stimulating the growth of the hair.
Dose.—½ to 2 decimils (0.05 to 0.2 milliliters) (1 to 3 minims).
- Spiritus Rosmarini, B.P.—SPIRIT OF ROSEMARY.
- Oil of rosemary, to; alcohol, sufficient to produce 100. This preparation is five times the strength of Spiritus Rosmarini, B.P., 1885. Spirit of rosemary is used chiefly as a perfume for hair lotions.