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 in the damask rose (_R.

damascena_), a variety induced by long cultivation, as it is not to be

found wild. It forms a bush, usually three to four feet, but sometimes six

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 constitutent of the otto

is a liquid containing oxygen, the solid hydrocarbon or stearoptene, with

which it is combined, being absolutely devoid of perfume. The proportion

which this inodorous solid constituents 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 61° to 64°

Fahr., an Indian sample required 68° Fahr.; one from the South of France,

70° to 73° Fahr.; one from Paris, 84° Fahr.; and one obtained in making

rose-water in London, 86° to 89½° Fahr. 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 Perso-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--4,000 to India, 1,500

to Java, 200 to Aden and the Red 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

Ghazipur, 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 1 rupee's weight (176 gr.) of otto; (_b_) 200,000 to make the same

weight; (_c_) 1,000 roses afford less than 2 gr. of otto. The color ranges

from green to bright-amber, and reddish. The oil (otto) is the 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, 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 flower yielding about 1 dr. 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 stearoptene than

the Turkish, nine grammes crystallizing in a liter (1¾ pint) of alcohol at

the same temperature as 18 grammes 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, ten

kilos. of roses being required to impregnate one kilo. of fat. The price of

the roses varies from 50c. to 1 fr. 25c. 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 southern slopes of the central Balkans, and approximately included

between the 25th and 26th degrees of east longitude, and the 42d and 43d of

north latitude. The chief rose-growing districts are Philippopoli, Chirpan,

Giopcu, Karadshah-Dagh, Kojun-Tepe, Eski-Sara, Jeni-Sara, Bazardshik, and

the center 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 1859--42 belong to it. The only place affording

otto on the northern side of the Balkans is Travina. 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° Fahr. at noon,

and 68° Fahr. in the evening. The rose-bushes nourish best and live longest

on sandy, sun-exposed (south and south-east 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 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 lb. of roses, not previously deprived of their

calyces, and double the volume of spring water. The distillation is carried

on for about l½ hours, 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 1¼ gallon. It is kept in them for a day or two, at a

temperature exceeding 59° Fahr., 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 stearoptene, 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

kilos. of roses give 1 kilo. of oil.

Pure otto, carefully distilled, is at first colorless, but speedily becomes

yellowish; its specific gravity is 0.87 at 72.5° Fahr.; its boiling-point

is 444° Fahr.; it solidifies at 51.8° to 60.8° Fahr., 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° Fahr.; fraudulent additions lower the congealing

point. The crystals of rose-stearoptene are light, feathery, shining

plates, filling the whole liquid. Almost the only material used for

artificially heightening the apparent proportion of stearoptene 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° Fahr., whereas

stearoptene fuses at 91.4° Fahr. 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-yaghi_ 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 lb. 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

_kunkumas_, holding from 1 to 10 lb., 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 _midkals_ (of about 3 dwt. troy), or 4,226

lb. av.; 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

Philippopolis, chiefly to France, Australia, America, and Germany.

--_Jour. Soc. of Arts._

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Scientific American Supplement, No. 275, April 9, 1881 · 第 58 / 67 题