The profitable cultivation of roses for the preparation of otto is limited chiefly by climatic condi tions. The odoriferous constituent of the otto is a liquid contaiuing oxygen, the solid hydrocarbon or stearoptene, 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 stearoptene is also shown by the progressively heightened fusing-point of rose-oils from different sources : thus, while Bulgarian oil fuses at about 16°-18° (61°-64° F.), an Indian sample required 20° (68° F.) ; one from S. France, 21°-23° (70°-73° F.) ; one from Paris, 29° (84° F.) ; and one obtained in making rose-water in Loudon, 30°42° (86°-89° F.). Even in the Bulgarian oil, a notable difference is observed between that produced on the hills, and that from 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, north-west of Mosul, was famous for it in the 14th century. Shiraz, in the 17th century, prepared both rose-water and otto, for export to other parts of Persia, as well as all over India. The rem Indian trade in rose-oil, which continued to possess considerable importance in the third quarter of the 18th 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, were-4000 to India, 1500 to Java, 200 to Aden and the Red Sea, 1000 to Muscat and Dependencies, 200 to Arab coast of Persian Gulf, and Bahrein, 200 to Persian coast and Mekran, and 1000 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 : 2200 to Koweit, Busrah, and Bagdad ; rose-water : 200 to Arab coast of Persian Gulf, and 1000 to Koweit, Busrah, and Bagdad.
India itself has a considerable area devoted to rose-gardens, as at Ghazipur, Lahore, Amritzur, and other places, the kind of rose being R. damascene, 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 maks 1 rupee's weight (176 gr.) of otto ; (b) 200,000 to make the same weight ; (c) 1000 roses afford less than 2 gr. of otto. The colour ranges from green to bright-amber and reddish. The oil (otto) is most carefully bottled ; the receptacles are hermetically sealed with wax, and ex posed 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, south-west 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 lb. of the flowers yielding about 1 dr. of otto. Genoa occasionally imports a little of this product, which is of excellent quality. In S. France, rose-gardens occupy a large share of attention, about Grasse, Cannes, and Nice ; they chiefly pro duce 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 stearoptene than the Turkish, 9 grin. crystallizing in a litre (lf pint) of alcohol at the same temperature as 18 grm. 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 kilo, of roses being required to impregnate 1 kilo. of fat. The price of the roses varies from 50 c. to 1 fr. 25 c. per kilo.
But the one commercially important source of otto of roses is a circumscribed patch of ancient Thrace or modern Bulgaria, stretching along the S. slopes of the central Balkans, and approxi mately included between the 25th and 26th degrees of E. longitude, and the 42nd and 43rd degrees of N. latitude. The chief rose-growing districts are Philippopli, Chirpan, Giopcu, Karadshah Dagh, Kojun-Tepe, Eski-Sara, Jeni-Sara, Bazardahik, and the centre and headquarters of the industry, Kazanlik (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 123 Thracian localities carrying on the preparation of otto in 1877—they numbered 140 in 1850-42 belong to it. The only place affording otto on the N. side of the Balkans is Travina. The geological formation throughout is essentially 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 28° (82° F.) at noon, and 20° (68° F.) in the evening. The rose-bushes flourish best and live longest on sandy, sun-exposed (S. and S.-E. 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.