Rose Oil, or Otto of Roses.
BY CHARLES G. WARNFORD LOCK.
This celebrated perfume is the volatile essential oil distilled from the flowers of some varieties of rose. The botany of roses appears to be in a transition and somewhat unsatisfactory state. Thus the otto-yielding rose is variously styled Rosa damascena, R. sempervirens, R. moschata, R. gallica, R. centifolia, R. provincialis. It is pretty generally agreed that the kind grown for its otto in Bulgaria is the damask rose (R. damascena), a variety induced by long cultivation, as it is not to be found wild. It forms a bush, usually 3 to 4 feet, but sometimes 6 feet high; its flowers are of moderate size, semi-double, and arranged several on a branch, though not in clusters or bunches. In color they are mostly light red; some few are white, and said to be less productive of otto.
The utilization of the delicious perfume of the rose was attempted, with more or less success, long prior to the comparatively modern process of distilling its essential oil. The early methods chiefly in vogue were the distillation of rose water, and the infusion of roses in olive oil, the latter flourishing in Europe generally down to the last century, and surviving at the present day in the south of France. The butyraceous oil produced by the distillation of roses for making rose water in this country is valueless as a perfume, and the real otto was scarcely known in British commerce before the present century.
The profitable cultivation of roses for the preparation of otto is limited chiefly by climatic conditions. The odoriferous constituent of the otto is a liquid containing oxygen, the solid hydrocarbon or stearopten, with which it is combined, being absolutely devoid of perfume. The proportion which this inodorous solid constituent bears to the liquid perfume increases with the unsuitability of the climate, varying from about 18 per cent. in Bulgarian oil to 35 and even 68 per cent. in rose oils distilled in France and England. This increase in the proportion of stearopten is also shown by the progressively heightened fusing point of rose oils from different sources; thus while Bulgarian oil fuses at about 61° to 64°F., an Indian sample required 68°F., one from the south of France 70° to 73°F., one from Paris 84°F., and one obtained in making rose water in London 86° to 89.5°F. Even in the Bulgarian oil a notable difference is observed between that produced on the hills and that on the lowlands.
It is, therefore, not surprising that the culture of roses, and extraction of their perfume, should have originated in the East. Persia produced rose water at an early date, and the town of Nisibin, northwest of Mosul, was famous for it in the fourteenth century. Shiraz, in the seventeenth century, prepared both rose water and otto for export to other parts of Persia as well as all over India. The Perso-Indian trade in rose oil, which continued to possess considerable importance in the third quarter of the eighteenth century, is declining, and has nearly disappeared; but the shipments of rose water still maintain a respectable figure. The value, in rupees, of the exports of rose water from Bushire in 1879 was—4,000 to India, 1,500 to Java, 200 to Aden and the Bed Sea, 1,000 to Muscat and dependencies, 200 to Arab coast of Persian Gulf and Bahrein, 200 to Persian coast and Mekran, and 1,000 to Zanzibar. Similar statistics relating to Lingah, in the same year, show—Otto: 400 to Arab coast of Persian Gulf and Bahrein, and 250 to Persian coast and Mekran. And Bahrein, Persian otto: 2,200 to Koweit, Busrah and Bagdad; rose-water: 200 to Arab coast of Persian Gulf, and 1,000 to Koweit, Busrah and Bagdad.
India itself has a considerable area devoted to rose gardens, as at Ghazi-pur, Lahore, Amritzur, and other places, the kind of rose being R. damascena, according to Brandis. Both rose water and otto are produced. The flowers are distilled with double their weight of water in clay stills; the rose water (goolabi pani) thus obtained is placed in shallow vessels, covered with moist muslin to keep out dust and flies, and exposed all night to the cool air or fanned. In the morning, the film of oil which has collected on the top is skimmed off by a feather, and transferred to a small phial. This is repeated for several nights, till almost the whole of the oil has separated. The quantity of the product varies much, and three different authorities give the following figures: (a) 20,000 roses to make one rupee's weight (176 grains) of otto; (b) 200,000 to make the same weight; (c) 1,000 roses afford less than two grains of otto. The color ranges from green to bright amber, and reddish. The oil (otto) is most carefully bottled; the receptacles are hermetically sealed with wax, and exposed to the full glare of the sun for several days. Rose water deprived of otto is esteemed much inferior to that which has not been so treated. When bottled it is also exposed to the sun for a fortnight at least.
The Mediterranean countries of Africa enter but feebly into this industry, and it is a little remarkable that the French have not cultivated it in Algeria. Egypt's demand for rose water and rose vinegar is supplied from Medinet Fayum, Southwest of Cairo. Tunis has also some local reputation for similar products. Von Maltzan says that the rose there grown for otto is the dog-rose (R. canina), and that it is extremely fragrant, 20 lbs. of the flowers yielding about one drachm of otto. Genoa occasionally imports a little of this product, which is of excellent quality. In the south of France rose gardens occupy a large share of attention, about Grasse, Cannes and Nice; they chiefly produce rose water, much of which is exported to England. The essence (otto) obtained by the distillation of the Provence rose (R. provincialis) has a characteristic perfume, arising, it is believed, from the bees transporting the pollen of the orange flowers into the petals of the roses. The French otto is richer in stearopten than the Turkish, 9 grams crystallizing in a liter of alcohol at the same temperature as 18 grams of the Turkish. The best preparations are made at Cannes and Grasse. The flowers are not there treated for the otto, but are submitted to a process of maceration in fat or oil, 10 kilograms of roses being required to impregnate 1 kilogram of fat. The price of the roses varies from .50 cents to 1 franc 25 cents per kilogram.
But the one commercially important source of otto of roses is a circumscribed patch of ancient Thrace or modern Bulgaria, stretching along the southern slopes of the central Balkans, and approximately included between the 25th and 26th degree of east longitude and the 42d and 43d degree of north latitude. The chief rose growing districts are Philippopolis, Chirpan, Giopcu, Karadshah-Dagh, Kojun-Tepe, Eski-Sara, Jeni-Sara, Bazardshik, and the centre and headquarters of the industry, Kaz-aniik (Kisanlik), situated in a beautiful undulating plain, in the valley of the Tunja. The productiveness of the last-mentioned district may be judged from the fact that, of the one hundred and twenty-three Thracian localities carrying on the preparation of otto in 1877—they numbered one hundred and forty in 1859—forty-two belong to it. The only place affording otto on the northern side of the Balkans is Travino. The geological formation throughout is syenite, the decomposition of which has provided a soil so fertile as to need but little manuring. The vegetation, according to Baur, indicates a climate differing but slightly from that of the Black Forest, the average summer temperatures being stated at 82° F. at noon and 68°F. in the evening. The rose bushes flourish best and live longest on sandy, sun-exposed (south and southeast aspect) slopes. The flowers produced by those growing on inclined ground are dearer and more esteemed than any raised on level land, being 50 per cent. richer in oil, and that of a stronger quality. This proves the advantage of thorough drainage. On the other hand, plantations at high altitudes yield less oil, which is of a character that readily congeals from an insufficiency of summer heat. The districts lying adjacent to and in the mountains are sometimes visited by hard frosts, which destroy or greatly reduce the crop. Floods also occasionally do considerable damage. The bushes are attacked at intervals and in patches by a blight similar to that which injures the vines of the country.
The bushes are planted in hedge-like rows in gardens and fields, at convenient distances apart, for the gathering of the crop. They are seldom manured. The planting takes place in spring and autumn; the flowers attain perfection in April and May, and the harvest lasts from May till the beginning of June. The expanded flowers are gathered before sunrise, often with the calyx attached; such as are not required for immediate distillation are spread out in cellars, but all are treated within the day on which they are plucked. Baur states that, if the buds develop slowly, by reason of cool damp weather, and are not much exposed to sun heat when about to be collected, a rich yield of otto, having a low solidifying point, is the result, whereas, should the sky be clear and the temperature high at or shortly before the time of gathering, the product is diminished and is more easily congealable. Hanbury, on the contrary, when distilling roses in London, noticed that when they had been collected on fine dry days the rose water had most volatile oil floating upon it, and that, when gathered in cool and rainy weather, little or no volatile oil separated.
The flowers are not salted, nor subjected to any other treatment, before being conveyed in baskets on the heads of men and women, and backs of animals, to the distilling apparatus. This consists of a tinned-copper still, erected on a semicircle of bricks, and heated by a wood fire; from the top passes a straight tin pipe, which obliquely traverses a tub kept constantly filled with cold water, by a spout, from some convenient rivulet, and constitutes the condenser. Several such stills are usually placed together, often beneath the shade of a large tree. The still is charged with 25 to 50 lbs. of roses, not previously deprived of their calyces, and double the volume of spring water. The distillation is carried on for about one hour and a half, the result being simply a very oily rose water (ghyul-suyu). The exhausted flowers are removed from the still, and the decoction is used for the next distillation instead of fresh water. The first distillates from each apparatus are mixed and distilled by themselves, one-sixth being drawn off; the residue replaces spring water for subsequent operations. The distillate is received in long-necked bottles, holding about 1 1/4 gallon. It is kept in them for a day or two, at a temperature exceeding 59°F., by which time most of the oil, fluid and bright, will have reached the surface. It is skimmed off by a small, long-handled, fine-orificed tin funnel, and is then ready for sale. The last-run rose water is extremely fragrant, and is much prized locally for culinary and medicinal purposes. The quantity and quality of the otto are much influenced by the character of the water used in distilling. When hard spring water is employed, the otto is rich in stearopten, but less transparent and fragrant. The average quantity of the product is estimated by Baur at 0.037 to 0.040 per cent.; another authority says that 3,200 kilograms of roses give 1 kilogram of oil.
Pure otto, carefully distilled, is at first colorless, but speedily becomes yellowish; its specific gravity is 0.87 at 72.5°F.; its boiling point is 444°F.;
it solidifies at 51.8° to 60.8°F. or still higher; it is soluble in absolute alcohol and in acetic acid. The most usual and reliable tests of the quality of an otto are (1) its odor, (2) its congealing point, (3) its crystallization. The odor can be judged only after long experience. A good oil should congeal well in five minutes at a temperature of 54.5°F.; fraudulent additions lower the congealing point. The crystals of rose-stearopten are light, feathery, shining plates, filling the whole liquid. Almost the only material used for artificially heightening the apparent proportion of stearopten is said to be spermaceti, which is easily recognizable from its liability to settle down in a solid cake, and from its melting at 122°F., whereas the stearopten fuses at 81.4°F. Possibly paraffin wax would more easily escape detection.
The adulterations by means of other essential oils are much more difficult of discovery, and much more general; in fact, it is said that none of the Bulgarian otto is completely free from this kind of sophistication. The oils employed for the purpose are certain of the grass oils (Andropogon and Cymbopogon spp.), notably that afforded by Andropogon Schoenanthus, called idris-aghi by the Turks, and commonly known to Europeans as "geranium oil," though quite distinct from true geranium oil. The addition is generally made by sprinkling it upon the rose leaves before distilling. It is largely produced in the neighborhood of Delhi and exported to Turkey by way of Arabia; it is sold by Arabs in Constantinople in large bladder-shaped tinned-copper vessels, holding about 120 lbs. As it is usually itself adulterated with some fatty oil, it needs to undergo purification before use. This is effected in the following manner: The crude oil is repeatedly shaken up with water acidulated with lemon juice, from which it is poured off after standing for a day. The washed oil is placed in shallow saucers, well exposed to sun and air, by which it gradually loses its objectionable odor. Spring and early summer are the best seasons for the operation, which occupies two to four weeks, according to the state of the weather and the quality of the oil. The general characters of this oil are so similar to those of otto of roses—even the odor bearing a distant resemblance—that their discrimination when mixed is a matter of practical impossibility. The ratio of the adulteration varies from a small figure up to 80 or 90 per cent. The only safeguard against deception is to pay a fair price and to deal with firms of good repute, such as Messrs. Papasoglu, Manoglu & Son, Ihmsen & Co. and Holstein & Co., in Constantinople.
The otto is put up in squat-shaped flasks of tinned copper called kunku-mas, holding from 1 to 10 lbs. and sewn up in white woolen cloths. Usually their contents are transferred at Constantinople into small gilded bottles of German manufacture for export. The Bulgarian otto harvest, during the five years 1867-71, was reckoned to average somewhat below 400,000 meticals, miskals or midfsals (of about 3 dwt. troy), or 4,226 lbs. avoirdupois; that of 1873, which was good, was estimated at 500,000, value about £700,000. The harvest of 1880 realized more than £1,000,000, though the roses themselves were not so valuable as in 1876. About 300,000 meticals of otto, valued at £932,077, were exported in 1876 from Phillippopolis, chiefly to France, Australia, America and Germany.—Phar. Jour. and Trans., April 30, 1881, from Jour. Soc. Arts, Feb. 11, 1881.
The American Journal of Pharmacy, Vol. 53, 1881, was edited by John M. Maisch.