Oleum Rosae. Br. Oil of Rose.

Related entry: Rose

"Oil of Rose is the oil distilled from the fresh flowers of Rosa damascena, Linn." Br.

Oleum Rosarum; Attar or Otto of Rose; Huile volatile de Rose pale, Fr. Cod.; Essence de Rose, Fr.; Oleum Rosae, P. G.: Rosenöl, G.; Essenza de rose. It.

Oil of Rose was not admitted to the U. S. P. IX. Fats and oils saturated with the rose perfume have been used since the earliest times. Of the seven thousand or more cultivated varieties of rose only a few are used for the production of oil. The chief of these is Rosa damascena, which is supposed to be a hybrid between R. gallica and R. canina. The volatile oil from this species is commonly called attar, otto, or essence of roses. It is prepared on a large scale in Turkey in Europe, especially in the Balkan Mountains, in Egypt, Persia, Cashmere, India, and other countries of the East, but European and American commerce is at present supplied chiefly from the region constituting the southern slope of the Balkans, and to some extent, from flowers cultivated in Germany. Synthetic Oil of Rose has entered commerce. The Bulgarian production of rose oil for 1913 amounted to 3600 kilos. (Schim. Rep., Oct., 1913.) The roses are gathered in May, and are distilled with the green leaves of the calyx. From thirty to sixty pounds are put into a tinned copper boiler, of the capacity of about 150 pounds, nearly filled with water. The heat is applied over an open fire, and a boiling temperature is continued for two hours, when the first part of the distilled fluid is returned to the boiler, and the process is continued to completion. The oil collects on the top of the water in the receiver, when it is removed from time to time as it accumulates. (P. J., June, 1872, p. 1051.) In the south of France a small quantity of oil of rose is prepared by distilling the petals with water and separating the oil which floats to the surface. The annual output of the oil is small, most of it being marketed in the form of rose water of which over 3,600,000 liters are produced annually. (Schim. Rep., Oct., 1907.)

Oil of rose is furnished in very minute proportion, not more than three drachms having been obtained by Polier in Hindostan, from 100 pounds of the petals. It is usually imported in small bottles, and is very costly. Oil of rose was at one time prepared in Macedonia by crushing the petals in mills, expressing the fluid part, filtering it, and then exposing it to the sun in small glass vessels. The oil gradually collects on the surface of the liquid, and is removed. (Ph. Cb., 1847, p. 783.) Landerer states that at Damascus and in other parts of Asia Minor the oil is prepared by dry distillation. The buds, being collected before sunrise, are placed in a glass retort, and the distillation is effected by a salt water bath, care being taken so to regulate the heat as not to scorch the petals. The water of the fresh roses and their oil come over together, and the latter, floating on the top, is readily separated.

For an account by R. Bauer of Constantinople, of oil of rose, its production, properties, adulteration, etc., see P. J., Dec., 1867, 286; also A. J. P., 1881, 367.

The experiments of Schimmel are said to indicate that the oil of rose can be prepared from German-grown flowers with commercial success. It is affirmed that the product is superior to the Turkish oil in fineness and strength of aroma, and also that it differs in haying a higher congealing point, German oil solidifying at 32° C. (89.6° F.), Turkish oil at 20° C. (68° F.). For an account of its production, see P. J., Aug., 1886; also P. J., 1893, 262.

Oil of rose is nearly colorless, or presents some shade of green, yellow, or red, but, according to Polier, the color is no criterion of its value. Its odor is very powerful and diffusive. At 32.2° C. (90° F.) its sp. gr. is 0.832. Alcohol dissolves it, though not freely when cold. It was officially described in U. S. P. VIII as if a pale yellowish, transparent liquid, having the strong, fragrant odor of rose, and a mild, slightly sweetish taste. Specific gravity: 0.855 to 0.865 at 25° C. (77° F.). The addition of 70 per cent. alcohol precipitates the paraffin hydrocarbons of the Oil, but forms a clear solution with its other constituents, the solution being slightly acid to litmus T.G. The congealing point, when determined according to the following method, should be between 18° and 22° C. (64.4° and 71.6° F.). Introduce about 10 mils of Oil into a test-tube of about 15 Mm. diameter; insert a thermometer in such a manner that it touches neither the bottom nor the sides of the tube. Raise the temperature of the Oil in the tube from 4° to 5° above the saturation point by grasping it in the hand, and shake the tube gently. Allow the Oil to cool, and when the first crystals appear, note the temperature. This is regarded as the congealing point; a second test should be made for confirmation." U. S. VIII.

"A pale yellow or yellowish-green crystalline mass, semi-solid at ordinary temperatures. Strong, fragrant, rose-like odor; taste sweetish. Specific gravity at 30° C. (86° F.) (compared with water at 15.5° C. (60° F.)) 0.854 to 0.862; optical rotation -2° to -4°; refractive index at 25° C. (77° F.) 1.456 to 1.465; melting point 20° to 23° C. (68°-73.4° F.)." Br.

Oil of rose consists of two portions, one liquid, the other solid at ordinary temperatures. These may be separated by freezing the oil and compressing it between folds of blotting paper, which absorbs the liquid oil and leaves the concrete stearopten. The liquid portion is oxygenated, while the solid portion, which is odorless when pure, consists of a mixture of several hydrocarbons, one of which melts at from 35.5° to 36.5° C. (96°-97.7° F.), and is a paraffin of the formula C16H34. A sample of oil of rose distilled in Leipsic in 1884 yielded 28 per cent. of this stearopten, an inferior oil distilled in London gave 68 per cent., and a very good oil from the Balkans gave 9.20 per cent. The oxygenated portion consists of the two alcohols, C10H18O geraniol, and C10H20O citronellol, the former constituting 75 per cent. of the oil. The rhodinol of Eckart was a mixture of these two alcohols. (Schim. Rep., April, 1898, 40.) While these two alcohols are mainly found in rose oil in the free state, esters of the same are also present in amounts varying from 2.5 to 3.5 per cent. (Gildemeister and Hoffmann, Aetherische Oele, p. 565.) Linalool, citral and phenyl ethyl alcohol are also present in small amounts.

Oil of santal, other volatile oils, fixed oils, spermaceti, etc., are said to be added almost universally as adulterations. The volatile additions may be detected by their not being concrete; the fixed, by the greasy stain they leave on paper when heated. Guibourt has offered certain tests by which he thinks the purity of the oil may be determined. (See A. J. P., xxi, 318.) A. Ganswindt recommends the following tests. Agitate 1 drop of the oil with 45 Gm. of warm water, and sprinkle the solution in a moderately warm room, which will soon be filled with a rose odor, in which foreign odors may be detected without difficulty. An adulteration with a fixed oil produces a permanent grease stain upon paper, and spermaceti is left behind on the evaporation of a few drops of the oil from a watch crystal in a water bath. On mixing a few drops of pure oil of rose with an equal bulk of sulphuric acid, the rose odor is not changed, but oils used for adulteration change their odor, which becomes apparent in the rose odor. Or 5 drops of the oil are mixed in a dry test tube with 20 drops of pure concentrated sulphuric acid; when the mixture is cool it is agitated with 20 Gm. of absolute alcohol, when a nearly clear solution should be obtained, which, heated to boiling, remains clear yellowish-brown on cooling. In the presence of the oil of rose geranium, palmarosa, etc., the alcoholic mixture is turbid, and on standing separates a deposit without becoming clear. (Seifens. Ztg., 1881, p. 32; A. J. P., May, 1881.) The oil of one of the sweet scented Pelargoniums, perhaps the rose geranium, is much employed in Turkey for the purpose of adulteration. According to Hanbury, who appears to have thoroughly investigated the subject, two substances especially are used in Constantinople for adulterating the oil— one spermaceti, the other a volatile oil produced by certain grasses in the East Indies belonging to the genus Andropogon, large quantities of which are exported from Bombay, partly directly to Europe, partly through the Arabian Gulf, whence it reaches Constantinople. The same oil is imported into London under the name of Turkish essence of geranium, or geranium oil.

Tedermann (Zeit. An. Chem; 1895, 5) reached the conclusion, after much experimenting, that there is no reliable chemical or physical test for the adulteration of oil of rose with geranium oil. The sense of smell, according to Conroy, furnishes the best means of determining the quality; he recommends the dissolving of one drop of oil of rose in twenty drops of alcohol, pouring the solution in one fluidounce of warm water, shaking, and comparing the odor with that of a standard sample treated in the same way. (P. J., 1896, 474; see also C. D., 1897, 53.) O. Helm (A. Pharm., 1885) states that the test with a mixture of five parts of chloroform and twenty parts of alcohol cannot be relied upon, as no separation of crystalline scales took place in four different rose oils which were doubtless genuine. But Flückiger, on the other hand, stated that in an experience of many years it had never failed. According to Bauer, the best tests of the purity of the oil are found in its congealing, in five minutes, at a temperature of 12.5° C. (54.5° F.), and its crystallizing, as a solid mass, in light, shiny plates, present everywhere throughout the liquid. These crystals are truncated semi-sided prisms, the angles of which are unequal, and which must be classed in the rhombic system. This stearoptene melted and allowed to cool, crystallizes in a manner so complete that the microscope can readily reveal the presence of foreign substances, such as spermaceti, fatty bodies, wax, and other analogous amorphous substances.

Oil of rhodium (Oleum ligni Rhodii, Aspalathum). This oil was attributed by Lewis to the Convolvulus Scoparius, but according to Holvaes (Perfume and Essential Oil Record,1911, ii, p. 29) is the product of a species of Genista, either G. canariensis or virgata. It is used to adulterate oil of rose. Guaiac wood oil is also occasionally used for the same purpose. A factitious oil of rhodium is sometimes sold as a lure for rats and other animals. It is made from oil of copaiba flavored with a trace of oil of rose. The synthetic oil of rose has largely replaced that obtained by distillation.

Oil of rose may be added, as a grateful perfume, to various spirituous preparations for internal use, and to cerates and ointments.

Off. Prep.—Unguentum Aquae Rosae, Br.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.