Oil of Ravensa′ra. Syn. Oleum ravensaræ, L. From the roots of Ravensara aromatica. Chiefly used to adulterate oil of cloves, which it somewhat resembles.
Oil of Rho′dium. Syn. Oleum rhodii, L. Said to be derived from the wood of a species of Rhodoriza. Very fluid and limpid; pale yellow; soon darkens by age and exposure; tastes bitter and aromatic; has a modified odour of roses. Chiefly used as a substitute for otto of roses in cheap perfumery, and to adulterate it. Oil of sandal-wood is frequently sold for it. Prod. 1% to 16%. See Oil of Roses (below).
Oil of Ro′′ses. Syn. Oleum rosæ, L. Prep. 1. From the petals of Rosa sempervirens (Linn.), or the musk rose, as oil of cloves, observing to keep the water in the worm-tub at 85° Fahr., and afterwards subjecting the water in the receiver to refrigeration. Resembles
otto of roses, of which it is merely a variety. Prod. 1⁄20 to 1⁄16 of 1%.
2. (Attar of roses, Otto of r.; Oleum rosæ—Ph. E.) From the petals of Rosa centifolia and Rosa sempervirens (damask and musk rose), principally the first, by saturating the water, by returning it repeatedly on fresh flowers, and then exposing it to a low temperature. In the East Indies it is obtained by stratifying gingelly seeds in alternate layers with rose petals, for some days, and repeating the arrangement with fresh roses till the seeds are saturated, when the oil is expressed and distilled along with water. In the neighbourhood of Mecca the rose leaves are macerated in salt-and-water for 2 or 3 days, and then distilled, the water being received in separate receivers at different parts of the process. The water is afterwards exposed in porous earthenware vessels, tied over with linen, in trenches dug in the earth, and over which moistened straw is thrown, when in a short time the otto separates and floats on the surface.
Prop., &c. Colourless, or nearly so; odour intense, penetrating, and diffusive, and in a concentrated state far from pleasant, but when dilute very agreeable; taste, bland and sweetish; when pure, it congeals at 80°, and does not remelt until heated to fully 85° Fahr.; 1000 parts of alcohol of ·806 dissolve only 7 parts of otto at 57° Fahr., and only 33 parts at 72°. Sp. gr. ·832 at 90°, to water 1·000 at 60° Fahr. Prod. 100 lbs. of roses yield 2 to 3 dr.
Pur. Otto of roses is frequently adulterated with the oils of rhodium, sandal-wood, and geranium, and with camphor; and occasionally with spermaceti, to give the spurious compound the usual crystalline appearance. The following are reliable tests:—1. Pure otto has a bland, sweet taste; if it is bitter, it contains oil of rhodium or sandal-wood; if it is pungent, or ‘bites,’ the palate, it contains either oil of geranium or camphor, and probably both; if it imparts an unctuous sensation, it contains spermaceti.—2. Exposed for some hours to the fumes of a small quantity of iodide under a bell-glass in the cold, pure otto remains white, and continues so when exposed to the air; an adulterated sample, on the contrary, becomes yellow or brown, and afterwards, on exposure to the air, continues to darken in colour, until it becomes of a deep brown, or even perfectly black, according to the quantity of foreign oil present. A single drop may be thus tested.—3. (Guibourt.) One or two drops of the suspected oil are put into a watch-glass; the same number of drops of concentrated sulphuric acid are added, and the two fluids are mixed with a glass-rod. All the oils are rendered more or less brown by this proceeding; but, otto of roses retains the purity of its odour—oil of geranium acquires a strong and disagreeable odour, which is perfectly characteristic—the odour of the oil of
rhodium is increased, and becomes somewhat unctuous, and, in general, it acquires an odour distinctly like that of cubebs.
Oil of Rose′mary. Syn. Rosmarini oleum (B. P.), Oleum anthos, O. rorismarini, O. rosmarini (Ph. L. E. & D.), O. rorismarini essentialæ, L. From the flowering tops of Rosmarinus officinalis. In the Ph. L. English oil of rosemary (O. rosmarini, Anglicum) is ordered, as it is superior to that from abroad. Colourless; strongly fragrant, but scarcely agreeable unless compounded; carminative and stimulant. Boils at 365° Fahr. Sp. gr. ·910; recent,·897; rectified, ·8887. Prod. 3⁄4 to 1% (nearly).
Pur., &c. It is frequently adulterated with oil of turpentine. When pure it dissolves in all proportions in spirit of ·830. By age it deposits a crystalline stearoptene, and acquires a terebinthinate odour. It is chiefly used as a stimulant in liniments, hair oil, pomatums, &c.