Lately a combination of the écuelle and distilling processes has been introduced by Domenico Monfalcone, which has given excellent results. It is shown in Fig. 20. F F is a hollow cylinder, of sheet-iron, the interior surface of which is studded with a large number of small metallic knife-points. This cylinder revolves on two axles attached to it at diagonally opposite points. The cylinder having been half-charged with lemons, together with a small quantity of water, is set in motion by aid of the shafting and pulleys driven by the small steam engine. The fruits are thereby made to come in contact with the metallic lancets, and their whole surface gradually becomes punctured sufficiently to rupture the cells containing the volatile oil, which escapes. The cylinder F F has double walls, the space between them being intended for the circulation of a current of steam, which is admitted to heat the water and to facilitate the extraction of the oil, while at the same time the vapors are rarefied or aspirated by the vacuum pump L. The axles of the cylinder on both sides are hollow; that on the side looking towards the engine is imbedded in such a manner that steam from the boiler D may be admitted at will, either into the double walls of the cylinder, or into the interior of the cylinder itself, while the hollow passage in the other axle communicates with a condensing worm, G, the outlet of which, H, descends into a cylindrical vessel, I, intended to receive the condensed products, consisting of water and volatile oil. When the apparatus is first set in motion the pump L begins to produce a vacuum during the first revolutions of the cylinder. Steam being now cautiously admitted into the double walls of the cylinder, the water is raised to boiling at a comparatively low temperature, and the vapors charged with the volatile oil pass over into the receptacle, where they separate into two layers. The product obtained by this process is claimed to be equal in quality to that obtained by mechanical means, and the yield nearly double.
During the months of November to March the average yield from 1000 lemons in the factories of Palermo is 320 grammes of oil; in those of Messina, where a better quality of fruit is employed, the yield is about 400 grammes. The same number of lemons yield about 10 gallons of juice, the collection of which is, of course, a necessary accompaniment of the manufacture of volatile oil.
Pure oil of lemons is almost colorless and has the odor of the fruit. Its specific gravity varies between 0.8752 and 0.8785; it boils at 298.4° F., and is soluble in all proportions in absolute alcohol and glacial acetic acid. It contains, according to G. Bouchardat and J. Lafont, besides a little cymene, several hydrocarbons, the most abundant of which is citrene, C10H16, boiling near 352.5° F., having a rotatory power exceeding +105°, and yielding a solid optically inactive dihydrochloride.
Oil of lemons is frequently adulterated with oil of turpentine. This may be detected, according to G. Heppe, by slowly heating the oil in a dry test-tube with a small piece of copper butyrate to about 338° F., taking care that the temperature does not exceed 356°F. The copper salt will dissolve in pure oil of lemons with a green color, while in the presence of oil of turpentine a yellow turbid mixture is obtained, reddish-yellow cuprous oxide being separated. This test is also applicable to oils of bergamot and of orange-peel.
Lilac oil is obtained from the flowers of Syringa vulgaris, the lilac, by aqueous distillation and subsequent extraction with benzine. It is also frequently prepared by the absorption process. It is used for the most expensive perfumes, and is seldom found in commerce.
Limes, oil of (oleum limettæ), is derived from the rind of the fruit of Citrus limetta, or lime. The oil is obtained in the same manner as oil of lemons, which it somewhat resembles. Its mean specific gravity is 0.8734 at 84° F. The oil made by the écuelle process is of a decidedly yellow color, varying in intensity, being darker in the fresh product. The difference in flavor and aroma is so marked as scarcely to require any other means of distinguishing the oil made by the écuelle process from that obtained by distillation, the first having a decided fragrant lemon smell, whilst the distilled oil is very inferior, frequently possessing little more than the smell of turpentine. Large quantities of oil of limes are manufactured in Dominica, but most of the oil exported from there is of an inferior quality and was formerly solely used for adulterating oil of lemons. Lately it has also been employed for scenting soaps and in the manufacture of the common essences and perfumes.
Licari oil, linaloë oil, is obtained, partially in Mexico and partially in Cayenne, from the wood of the white cedar (bois de rose femelle), Licari canali. It is limpid, has an agreeable odor, reminding one of roses, and does not become solid at 4° F. Its specific gravity is 0.868 at 59° F., and it boils at 388.4° F.
Marjoram oils.—By distilling the leaves of Origanum marjorana, L., the marjoram oil (oleum marjoranæ) is obtained. It is yellowish or green-yellowish, but becomes reddish-brown by age. If badly kept it finally becomes thickly-fluid and sticky, sometimes depositing a reddish stearoptene. The odor of marjoram oil is less agreeable than that of the plant, and the taste peculiar, bitter, cooling. The oil dissolves readily in 90 per cent. alcohol, and when mixed with equal parts of it yields a clear solution. Its specific gravity is 0.89 to 0.91. It should be kept in entirely filled, well-closed bottles in a shady place. On coming in contact with air, it absorbs oxygen with avidity and forms a white, odorless, crystalline mass.
From Origanum vulgare, L., the ordinary marjoram oil (oleum origani vulgaris) is obtained. It is yellowish or reddish, limpid, of specific gravity 0.90 to 0.95, and has a camphor-like odor.
Spanish marjoram (oleum origani cretici) is obtained by distillation from the flowering plants of several varieties of marjoram (Or. creticum, Or. hirtum, Or. smyrnæum). It is brought into commerce from Trieste, Smyrna, Salonica, and other Mediterranean seaports. The oil exported from France appears to be derived from another variety of marjoram; at least it shows a different behavior and approaches more the ordinary marjoram oil. The genuine oil is thickly-fluid, generally yellow-brown; of specific gravity O.95 to O.97; has a strong, aromatic odor, and produces upon the tongue a sharp continued burning. It dissolves in equal parts of 90 per cent. alcohol. It is chiefly adulterated with copaiba oil, the presence of which can be recognized by the oil dissolving with greater difficulty.
The marjoram oils are but little used for perfuming purposes.
Mignonette oil (oleum résédæ). The well-known mignonette, Réséda odoratissima, yields a thick yellowish oil, either by maceration and absorption, or by extraction with ether or petroleum-ether. It has a penetrating, disagreeable odor, which can only be rendered agreeable by greatly diluting the oil. In gathering the flowers care must be had not to mix them with leaves, as this spoils the odor of the oil.
Myrrh oil (oleum myrthæ) is obtained from the leaves of Myrtus communis, L. It is yellowish, dextrorotatory, of specific gravity 0.910 at 60.8° F., and commences to boil at 320° F. As its principal constituents, Jahns has established a terpene (C10H16), boiling at from 316.4° to 320° F., and turning the plane of polarization to the right, and cineol (C10H16O), which boils at 348.8° F. Besides these principal constituents there seems to be present a very small quantity of a camphor, corresponding very likely to the formula C10H16O. Myrtol, which was formerly supposed to exist in myrtle oil, has been found to be a mixture of the dextrorotatory terpene and of cineol.
Nutmeg oils.—From mace, the fresh aril of the nutmeg (Myristica fragrans, Houtt, natural order Myristicaceæ), mace oil (oleum macidis), is obtained by distillation. It is straw-yellow or yellowish, later on yellow-reddish, clear, somewhat thickly-fluid, of a strong odor resembling that of mace, and a taste at first mild, but later on pungent and aromatic. It mixes clear in every proportion with absolute alcohol, but of 90 per cent. alcohol, 5 to 6 volumes are required for a clear solution. The specific gravity of the oil varies from 0.87 to 0.92. With iodine it detonates, vapors being emitted. The oil obtained from dried mace has a less agreeable odor.
The oil is frequently adulterated with tincture of nutmeg prepared with absolute alcohol. Such an adulteration, as well as any content of alcohol, is recognized by shaking 0.5 cubic centimeter of the oil with a grain of rosaniline. In the presence of alcohol the oil acquires a red coloration, while pure oil remains uncolored.
From the nutmegs, the seed of Myristica fragrans, freed from the seed-coat and aril, a volatile oil (oleum nucistæ æthereum) is also obtained by distillation. It is generally yellowish, seldom colorless, somewhat thickly-fluid and has the odor and taste of nutmegs. It is readily soluble in alcohol and ether and of specific gravity, 0.93 to 0.95. It consists of two oils, one specifically lighter and fluid, and the other heavy and crystalline. On standing it deposits a stearoptene, called myristicin.
The nutmeg oils are but seldom used in perfumery.
Opopanax oil is obtained from opopanax.[7] It is of gold-yellow color and an agreeable balsamic odor reminding one somewhat of myrrh. Its specific gravity is 0.9016, and it boils between 392° and 572° F.
On account of its strength, the oil must be very carefully handled in perfuming, but if used in the correct proportion it is very advantageous.
Orange-peel oil, also called Portugal oil or essence of Portugal, is obtained in Italy from the fresh peels of the orange, the fruit of Citrus vulgaris, Risso. It is prepared in a manner similar to that of oil of lemons (which see). In commerce a distinction is made between the Messina oil, which is of inferior quality, and the Calabria oil, which is of a better quality. The Messina oil has a yellow color, frequently not much darker than that of oil of lemons, while the color of Calabria oil is dark yellow, nearly brown. The oil prepared from the peels of the bitter orange (Citrus bigaradia, Duhamel), is of the same color as the sweet Messina oil. It is more used in the preparation of liqueurs than for perfuming. Orange-peel oils are limpid and have a specific gravity of 0.819 to 0.9. One part of orange-peel oil should, according to its age, dissolve clear in 5 to 10 parts of 90 per cent. alcohol.
Very similar to orange-peel oil, though differing somewhat in odor, is the mandarin oil obtained from the fresh peels of the mandarin orange, the fruit of Citrus sinensis. It is brought into commerce from Reggio and is said to form a constituent of the genuine ess-bouquet. It has a specific gravity of 0.852 at 50° F. and is dextrorotatory.
While from the peels the volatile oil is but seldom obtained by distillation, this process is exclusively used for gaining volatile oils from the flowers, leaves, and young branches. In this connection two kinds of volatile oil have chiefly to be considered, viz: orange-flower oil and petit-grain oil.
Orange-flower oil or neroli oil (oleum florum aurantii; ol. neroli; ol. naphæ) is obtained by distillation from the flowers of the bitter orange; while the flowers of the sweet orange yield the so-called neroli-Portugal oil, which is far inferior to the other.
On the French Riviera, the orange is especially cultivated for obtaining blossoms and leaves for distilling purposes. At Cannes, Le Cannet, Golfe-Juan, Vallauris, Biot, Vence, Le Bar, Antibes, Le Cap, Nice, and Mentone, the bitter orange, whose flowers are very numerous and especially suitable for perfumery, is chiefly cultivated. Cannes and Le Cannet alone possess 150,000 to 160,000 such trees, and Golfe-Juan and Vallauris 200,000. The flowers harvested in Golfe-Juan amount to about 700,000 lbs., in Le Cannet to about 330,000 lbs., at Cannes to about 130,000 lbs., and in Antibes, Mentone, and Nice to about 260,000 lbs. One orange tree yields, according to its age, from 2 to 17 lbs. of flowers. The distillation of neroli oil has also been lately commenced in Sicily and Calabria, but as far as quality is concerned, the oil thus far brought into commerce cannot compete with the French oil.
Oil of orange flowers is at first nearly colorless or straw-yellow, but becomes reddish-yellow when kept for some time. In a clear glass it opalizes bluish. It is limpid and has a slightly bitter taste and a strong but very delicious odor. Its specific gravity varies between 0.85 and 0.90. It is but sparingly soluble in water, but imparts to the latter an agreeable odor; the solution is colored red by sulphuric acid. With 1 to 2 parts of 90 per cent. alcohol, the oil gives a clear solution which becomes turbid by a further addition of alcohol and, after standing quietly, a flaky separation of stearoptene is observed. If not carefully kept the oil becomes darker and even acquires a disagreeable odor. By rectification with water oil thus spoiled can be restored. With sodium the oil does not evolve hydrogen gas; it detonates with iodine.
Of the various oils of orange blossoms occurring in commerce "Neroli petale" is the best.
Neroli oil being a very expensive oil is exposed to many adulterations. Mierzinski even asserts that no genuine unadulterated neroli oil occurs in commerce, because it is a well-known fact that what is sold as genuine, pure neroli oil, consists on an average of 4/8 genuine neroli oil, 1/8 oil of bergamot, and 3/8 petit-grain oil. Furthermore, it is no secret that besides the flowers of all kinds of Aurantiaceæ, unripe fruits or fresh peels of ripe fruits and even young shoots of the branches and leaves are subjected to distillation. This assertion perhaps goes too far, but nevertheless it is advisable to procure the oil only from a thoroughly reliable firm.
A very frequent adulteration consists in an addition of petit-grain oil. Such an addition can only be recognized by the taste and odor. For this purpose add to 3 drops of oil in a small bottle 10 grammes of distilled water, and, after shaking vigorously, test as to the odor and taste. According to Chevalier, pour 1 or 2 drops of the oil upon sugar and stir the latter in water; if the oil is not genuine the water acquires a bitter taste. Hager recommends the following test: Mix 3 drops of the oil in a test-tube with 40 to 50 drops of alcohol; add, after complete solution, about ⅓ the volume of the solution of concentrated sulphuric acid, and effect mixture by careful shaking. Pure oil gives a turbid, reddish, dark-brown mixture (with old oil, dark brown); almost all other oils, which may be substituted, give paler-colored (reddish, red, or ocher-color) mixtures; or, in case the genuine oil is adulterated with non-genuine, the mixture exhibits a considerably less dark-color. When this test has been several times executed with genuine oil, no room for doubt is left. If the mixture be diluted with four times its volume of water, it becomes yellowish and milky.
The odor of orange flowers is, according to Soubeiran, due to two volatile oils, of which the one having the most delicious odor is soluble in water. The other volatile oil, of which the neroli oil of commerce chiefly consists, is sparingly soluble in water, and does not possess such a delicious odor. This is the reason why good orange-flower water cannot be prepared by saturating water with neroli oil. The genuine orange-flower water is obtained as a by-product in distilling the oil.
Neroli oil is much used for the finer perfumes, it being especially a necessary constituent of eau de Cologne. It has to be carefully protected from air and light. For perfuming purposes it is only sufficiently ripe after having been stored for at least one year. If, however, it becomes too old, it inclines towards rancidity, which may be prevented by compounding it with an equal volume of fine spirit. Portugal oil being of inferior quality can only be used for lower grade products.
Petit grain oil (oleum petit grain) is obtained by distillation from the leaves, young shoots and unripe fruits of different Aurantiaceæ. The best oil is that distilled from the leaves of the bitter orange, it possessing an odor similar to that of neroli oil, but, of course, not so fine. Southern France was formerly the chief place for the production of this oil, but considerable quantities of it are now manufactured in Paraguay, and the oil at present brought from there into commerce being of quite a good quality and considerably cheaper than the French oil, has almost entirely supplanted the latter.
Orris root, oil of (oleum iridis), is obtained by distillation with steam from the rhizomes of Iris florentina, which is cultivated in Southern France, Dalmatia, and other regions. It has a yellow color and, at an ordinary temperature, a quite solid consistency like butter or wax, so that it can be rendered fluid only by heating. It consists chiefly of a rigid odorless body to which the liquid odoriferous oil adheres. The solid portion was formerly designated orris-stearoptene; according to Flueckiger it is, however, myristic acid.
Oil of orris root is one of the oils which keep for years without suffering injury. It is recommended to keep it in stock in alcoholic solution so that the myristic acid contained in it may to a certain degree be etherized, and cannot injuriously affect the odoriferous principle.
Oil of orris root serves as a substitute and for strengthening the natural odor of violets. It can, however, be employed only for very fine expensive perfumery since, on account of the very slight yield from the root (from 1000 parts ½ to ¾ part of oil), its price is very high, generally exceeding that of rose oil.
An admixture of other volatile oils of less value would render the oil fluid at the ordinary temperature.
Patchouli oil.—By the name of patchouli are known, according to L. Wray, Jr., the leaves of Pogostemon patchouli, Pellet, natural order Labiatæ, indigenous to the East Indies, and known and used for centuries in the various regions of China, Assam, and the Malayan Islands. Most of the patchouli comes from the East Indies. Before exportation it is sorted into three qualities: 1. Selected, consisting of leaves only. 2. Mixed, leaves with slight peduncles and few stems. 3. Stalky leaves. The best quality occurs seldom in commerce since the picking of the leaves does not cover the expense.
According to Wray, the leaves are intentionally mixed with those of the ruku (ocimum basilicum, L.), an herb indigenous to the Malayan Islands. The leaves of the latter are broader than those of pogostemon patchouli, and the stalks thinner and round. Seed-capsules are also frequently found among the leaves, though patchouli seldom flowers and bears seeds.
In Europe, patchouli has been an article of commerce since 1841. In the Orient it is highly esteemed as a perfume. The Arabs even ascribe remedial properties to it, and it is customary with them to fill their pillows with the leaves to protect them from infection and prolong their lives.
The peculiar, penetrating, though not exactly agreeable, odor of patchouli leaves, is due to a volatile oil, of which they contain 1.5 to 2 per cent. In the Orient this oil has for many years been obtained by distillation.
In the Penang market two kinds of oil, one green and the other gold-brown, are distinguished. Though both are sold at the same price, there is a greater demand for the green oil. According to the statements of the distillers, the brown oil is derived from the leaves of old plants and the green oil from the leaves of young plants. It would seem, however, that the color is dependent on the soil upon which the plants are grown, as well as upon atmospheric influences. When ruku is distilled with patchouli leaves, the oil is yellow and thickly-fluid.
In Germany, the oil is now distilled from imported leaves. It is thickly-fluid, of a brown color, and, in an undiluted state, possesses a disagreeable, almost musty odor. However, when sufficiently diluted and suitably mixed with other volatile oils, the odor is far more agreeable, and for this reason it has for some time played an important part in the manufacture of perfumery. It has the advantage of being very yielding and lasting, but, on the other hand, possesses the disadvantage of not combining with other perfumes, so that its odor is always perceptible. It should always be used in very small quantities or much diluted.
In commerce Penang oil and French oil are distinguished, the first having a specific gravity of 0.959 and the latter of 1.012. When kept for any length of time the oil deposits patchouli-camphor (C15H28O) in prismatic crystals of 1.045 specific gravity and melting at 127 to 129° F. These crystals have a peculiar, very lasting odor.
Patchouli oil is soluble in equal parts of 90 per cent. alcohol, the contrary indicating that it is not pure. It is chiefly adulterated with cedar oil.
Peppermint oil.—The Mentha family furnishes commerce with three oils differing essentially from each other—oil of curled mint, peppermint oil, and poley oil.
Oil of curled mint (oleum menthæ crispæ) is separated by distillation with water from the leaves of Mentha crispa, Linn. It is limpid, yellowish, sometimes greenish; in time it becomes darker and more thickly-fluid. Its specific gravity varies between 0.890 and 0.965. It has a strong odor of curled mint and a pungent, somewhat cooling, slightly bitterish taste. It is soluble in all proportions in 90 per cent. alcohol. In commerce a distinction is made between German and American oil of curled mint, the latter generally containing oil of turpentine and oil of sassafras. Odor, taste, and the alcohol test suffice for the determination of the quality of the oil.
Oil of curled mint contains a terpene, C10H16, and a body isomeric with carvol, the carvol of curled mint, C10H14O. Its specific gravity, boiling point and chemical properties are the same as those of the carvol of caraway oil, but it differs from it by its odor and turning the plane of polarization to the opposite direction. In conjunction with other volatile oils, oil of curley mint is sometimes used for perfuming soaps.
Peppermint oil (oleum menthæ piperitæ) is obtained from the fresh flowering peppermint, Mentha piperita, natural order Labiatæ. In commerce, German, English, American and Japanese peppermint oils are distinguished. As regards fineness, the German oil is inferior to the English and better kinds of American oils, but superior to the Japanese. The best and most expensive oil is the English so-called "Mitcham oil of peppermint," which dissolves in 50 parts of 50 per cent. spirit of wine and possesses a fine, pure taste, it being for this reason preferred by distillers for the fabrication of liqueurs. For perfuming purposes, however, the American as well as the German oils are very suitable. Of American oils that of H. G. Hotchkiss, L. B. Hotchkiss, Hale & Parshall, and Fritzsche Bros. enjoy a high reputation. The Japanese oil is distinguished from the rest by a peculiar train-oil-like odor and taste, and is in but little demand.
Crude oil of peppermint is yellowish to greenish and contains much mucus; it has therefore to be subjected to another distillation with water. The rectified oil is clear as water, limpid, of a strong but pleasant odor and a specific gravity of 0.900 to 0.902. Old oil thickens and then shows an acid reaction. The greater portion of the oil congeals at the freezing point of water; many kinds, however, requiring but slight cooling in order to become solid. The solid portion of the oil, Menthol, (C10H12,H2O) is a colorless, finely crystallized body with an intense odor of peppermint. It melts at 107.6° F., is quite fluid at an ordinary temperature and boils at 413.6° F. Menthol is found in all oils of peppermint most abundantly in the Japanese oil, which contains from 50 to 55 per cent. of it. Mitcham oil is also very rich in menthol, it containing from 40 to 45 per cent., while the American oil contains only from 20 to 25 per cent.
American, German and English oils of peppermint may be distinguished as follows: By adding to 5 or 6 drops of the oil, 25 to 30 drops of pure white concentrated sulphuric acid, American oil of peppermint becomes heated and emits vapors, the mixture acquiring a dark brownish red coloration. After mixing with 8 to 10 cubic centimeters of 90 per cent. alcohol, the fluid becomes turbid, pale yellowish brown, or reddish brown, and on boiling clear pale brown. When mixed with sulphuric acid, German oil of peppermint becomes heated without emitting vapors, becomes yellowish red, not very dark, and turbid. After diluting with alcohol, the fluid becomes turbid and yellowish red, and on boiling somewhat more transparent and currant-red. English oil of peppermint treated in the same manner as the others with sulphuric acid becomes very slightly heated without any emission of vapor. After diluting with alcohol, it becomes clear and raspberry red.
As adulterants of peppermint oil are mentioned: fat oils, alcohol, oil of turpentine, copaiba oil, mustard oil, and ginger oil. The most frequent adulteration is an admixture of oil of turpentine. It is recognized by the oil not dissolving clear in equal parts of 90 per cent. alcohol, as is the case with the pure product. To detect the presence of copaiba oil, mix 5 drops of the oil to be tested with 15 to 20 drops of fuming nitric acid, shake and allow it to stand for 1 to 2 hours. After this time the oily portion should be neither entirely nor partially congealed, but remain fluid. To detect traces of mustard oil, bring 10 drops of the oil into a wide reagent glass, then add 3 to 4 cubic centimeters of absolute alcohol, 2 to 3 drops of silver nitrate solution and 12 to 15 drops of ammonia. The mixture is clear and colorless, and remains so on heating to boiling. In the presence of mustard oil turbidity and blackening take place in consequence of the formation of silver sulphide. After boiling, allow the fluid to stand quietly for 2 or 3 hours. If it then shows a grayish turbidity, the oil is adulterated with another volatile oil.
Instead of pure American oil of peppermint, a product compounded with camphor oil, and mostly freed from menthol, is said frequently to occur in commerce. According to E. C. Federer, this is recognized by dissolving one volume of oil of peppermint in 2 volumes of 94 per cent. alcohol, adding water and shaking. Pure peppermint oil is then separated with a certain portion of the alcohol. For example, mix 10 cubic centimeters of oil of peppermint in a graduated cylinder of 45 to 50 cubic centimeters' capacity with 20 cubic centimeters of 94 per cent. alcohol, then add 10 cubic centimeters of water of 50° F. and shake. After allowing the mixture to stand quietly, two layers are formed, the upper one of which, if the oil is pure, will amount to 14 cubic centimeters, but only to 12.5 cubic centimeters if the oil is freed from menthol and compounded with camphor oil. A larger or smaller addition of water to the alcoholic mixture is without influence upon the height of the upper layer separated.
In perfumery peppermint oil serves chiefly for aromatizing dentifrices, etc. It should be kept in well-closed bottles in a shady place; an addition of 0.5 per cent. of alcohol helps to preserve the oil for a long time.
Poley oil (oleum menthæ pulegii).—In Southern France and Spain this oil is obtained by distillation from the leaves of Mentha pulegium. It has an odor resembling that of peppermint, is at first colorless, but soon becomes yellow, has a specific gravity of 0.927, boils at 361.4° to 370.4° F., and contains neither menthol nor carvol. It is used for perfuming herb soaps.
Pimento oil, or oil of allspice (oleum pimenta) from the bruised fruit of Eugenia pimenta, allspice, natural order Myrtaceæ. The oil is pale yellow, becoming reddish-brown by age; it has a very pungent taste and intense odor, very much resembling that of cloves. It is heavier than water, its specific gravity being from 1.021 to 1.037. It mixes with glacial acetic acid in all proportions. When treated with nitric acid, pure pimento oil assumes a red color, with strong effervescence.
Rose oil or attar of roses (oleum rosæ) comes almost exclusively from Bulgaria, where it is obtained by distillation with water from the flowers of Rosa damascena. The small quantities of an excellent quality of rose oil prepared in Southern France from Rosa provincialis remain in the country of their production and do not even cover the local demand. The small productions of Persia and India need also not be taken into consideration. In Tunis, where formerly much rose water was prepared from Rosa canina and also rose oil of a very fine quality, the distillation of roses has, according to Christo Christoff, been entirely abandoned, geranium oil only being now produced. In the summer of 1884, Schimmel & Co., of Leipzic, Germany, made the experiment to obtain oil on a large scale from indigenous roses. The result was very satisfactory, 2000 lbs. of rose leaves yielding about 1 lb. of oil, the extraordinarily agreeable odor of which was so superior to that of the Turkish oil, that notwithstanding the high price—double that of Turkish oil—it found ready purchasers. At the ordinary temperature the Leipzic oil is solid, it only melting at 89.6° F.
In Bulgaria, Kazanlik, in the Tundscha Valley, is the centre of the entire industry and the principal market. Rose oil is there called "gul-jag" (gul, the rose, and jag, oil). The annual production of Kazanlik and neighboring places, amounting 50 years ago to from 450 to 650 lbs., has within a few years risen to the enormous figure of 5500 lbs.
In Kazanlik two varieties of roses, known as the "white rose" and "red rose," are cultivated; the former being Rosa alba, L., and the latter Rosa damascena, Miller. By distillation the white rose yields an oil of little perfume, but rich in stearoptene. On account of its slight odor, the white rose is seldom distilled by itself, but occasionally white and red roses are mixed in order to obtain an oil rich in stearoptene, so that a fraudulent admixture of a larger quantity of geranium oil may be effected without great danger of detection. The large plantations consist only of bushes of red roses. But on the edges of the field a strip, a few feet wide, is planted with white roses, so that only flowers of little commercial value may be plucked by passers-by.
The flowers are gathered before sunrise, and, if possible, the same day subjected to distillation. The latter is effected in a very crude apparatus, over a direct fire. The flowers are distilled with double their weight of water, one-half of which is drawn off. The product of several operations thus obtained is combined and again distilled, when, however, only one-sixth is drawn off. This distillate is allowed to stand for one or two days in a place warmer than 59° F., when the oil floating on the top is skimmed off. It may be supposed that on an average 6600 lbs. of roses are required to obtain 2.2 lbs. of oil, and that these 6600 lbs. of roses correspond to an area of 1 hectare (2.471 acres) planted with rose bushes.
Pure, carefully-distilled rose oil is at first colorless, but soon turns yellowish.[8] Its specific gravity is between 0.830 and 0.890. It consists of a liquid oil and a stearoptene, the content of the latter varying very much. It is a pure hydrocarbon, odorless, of specific gravity, 0.840 to 0.860, and distils at 572° F. Hence it is lighter than the elæoptene on which alone the odor of the rose oil is dependent. Rose oil generally congeals between 50° and 60° F., though sometimes at a higher or lower degree, according to its content of stearoptene. While some oils require the cold of winter for congealing, others are in the heat of summer either entirely solid, or form a fluid filled with many crystals. The odor of rose oil is peculiarly honey-like, and too intense to be agreeable, its entire deliciousness being only developed by strong dilution, be it by dissolving in water or alcohol, or by distribution upon large quantities of rigid bodies, fats, soaps, etc. In alcohol it dissolves with greater difficulty than all other volatile oils, 1 part of it requiring for solution 140 to 160 parts of alcohol of 0.815 specific gravity.
The larger or smaller content of stearoptene in rose oil seems to be dependent on climatic conditions, it having been remarked that the quantity is the greater the lower the temperature of the region. The oil from the coldest and highest regions of the Balkan is richer in stearoptene than that from the lower and warmer regions.
The genuineness of rose oil is generally judged by its odor, its capacity of congealing, and the manner of its crystallization. The odor is by all means the most reliable criterion, but requires much experience, and especially reliable pure standard samples for comparison. The capacity of congealing at certain conditions of temperature, is, to be sure, also a requirement of genuine rose oil, but, as previously mentioned, this property varies very much, and is subject to different influences, so that a fixed standard at which pure rose oil must congeal cannot be established. Attention must, however, be called to the fact that the quality of a rose oil does by no means rise with its greater capacity to congeal, since only the liquid oxygenated portion possesses odor.
Schimmel & Co. bring at present into commerce a liquid rose oil freed from stearoptene which can be highly recommended for finer alcoholic perfumes. It remains fluid at 32° F., but in a cold mixture congeals to a gelatinous mass, and hence is not absolutely free from stearoptene. It has an extremely fine and powerful odor, and when dissolved in alcohol does not give the disagreeable crystalline separations of the ordinary rose oil, which produce a disturbing effect, especially in the preparation of extracts.
For the insulation and determination of the stearoptene in rose oil, Schimmel & Co. proceed as follows: Heat 50 grammes of oil together with 500 grammes of 75 per cent. alcohol to from 158° to 176° F. In cooling, the stearoptene separates nearly quantitatively. Separate it from the fluid, treat it again in the same manner with 200 grammes of 75 per cent. alcohol, and repeat the operation until the stearoptene is entirely free from odor. Two treatments of the crude stearoptene are generally sufficient. In this manner Schimmel & Co. obtained from 1887 German rose oil 32½ per cent. stearoptene, from 1888 German rose oil 34 per cent., from 1887 Turkish rose oil 12 to 13 per cent., and from 1888 Turkish rose oil 14 per cent.
It is evident that such a valuable product as rose oil is much subjected to adulteration, it being even said that oils containing scarcely 10 per cent. of genuine rose oil occur in the market. The chief adulterant used by the Bulgarians is the so-called geranium oil, but actually ginger-grass oil derived from India, which is brought by way of Arabia to Constantinople, and prepared for the purpose of adulterating rose oil by treatment with lemon juice and bleaching in the sun. The sophistication is generally effected by sprinkling the ginger-grass oil thus prepared upon the rose leaves before distilling. The general characters of this oil are so similar to those of rose oil that detection, when the adulteration is kept within certain limits, is very difficult, so that during the distilling time large buyers and exporters of rose oil are forced to pay, besides their other officers in Kazanlik, confidential native agents who constantly move around in the distilling regions and report where distillation has been carried on honestly, and where the ginger-grass oil bottle has been seen. However, the prepared ginger-grass oil is frequently not even distilled with the rose leaves, but simply mixed with the finished rose oil.
Whether a rose oil is free from geranium or ginger-grass oil is tested in Bulgaria, according to Christo Christoff, by the freezing method, which is, however, unreliable. It is based upon the fact that an addition of geranium oil reduces the congealing point of rose oil. Pure Bulgarian rose oil congeals at from 63.5° to 68° F.; by the addition of geranium oil, the same oil congeals at 61.25°, 59°, 56.75°, or at a still lower temperature, according to the quantity added. The buyer when purchasing oil carries with him two basins, one containing hot and the other cold water, which he mixes in order to obtain a fixed temperature, the operation being controlled by a Réaumur thermometer. In the water thus prepared he completely submerges a 20 gramme flask containing 15 grammes of the oil to be tested. In three minutes, needle-like crystals of the separating stearoptene must appear, and in ten minutes crystallization must be complete. According to the congealing point thus established, the product is paid for. Oil congealing below 59° F. being evidently adulterated is rejected and bargained for at a special price.
Many attempts have been made to fraudulently make this congelation appear within the limits of temperature permitted, paraffine which dissolves well in rose oil being formerly frequently added. In such case the oil may congeal at from 65.75° to 68° F., but the crystals are opaque, dirty yellow, and dissolve to a turbid paste which collects on the surface. The simplest method is to distil white roses with the red. The resulting product has not as fine an odor as that from red roses alone, but is richer in stearoptene. Such oil, which, unadulterated, congeals perhaps at 68° F., can by the addition of geranium oil be reduced to from 63.5° to 65.75° F., thus keeping within the limits permitted.
Numerous attempts have been made to find a rapid and sure way for the detection of geranium oil in rose oil, but thus far in vain. Attention must also be drawn to the fact that the adulterant is frequently itself adulterated with oil of turpentine before being sold to the distillers of rose oil.
Besides the above-mentioned ginger-grass oil, the actual geranium oils from Pelargonium odoratissimum and P. roseum, as well as rosewood oil, sandal-wood oil, spermaceti, paraffine, and fat oils have been mentioned as adulterants of rose oil. The geranium oils having a by-odor of lemon oil, by which their presence could be readily detected are not suitable for the purpose. Neither can rosewood or sandal-wood oils be used, or at least such adulteration would be so clumsy as to be immediately recognized. Attempts to adulterate rose oil by the addition of a fat crystallizable body together with another volatile oil fail on account of the characteristic properties of rose oil stearoptene, which resembles no other body at present known. While rose oil stearoptene is lighter than elæoptene and entirely volatile, spermaceti possesses essentially different qualities. It does not form such long and specifically light crystals as rose oil stearoptene; hence it readily separates on the bottom and on shaking exhibits a peculiar iridescent loamy formation. Furthermore it melts at 122° F., and not being volatile, leaves, on heating, a greasy stain upon paper, while the stearoptene melts at 95° F. and, on heating, volatilizes completely without leaving a greasy stain behind.
If a rose oil is to be tested, expose the bottle containing the oil to a moderate heat until the contents are entirely liquid; then gently shake the bottle in order to bring about an intimate mixture of elæoptene and stearoptene. Now pour some of the oil into a cylindrical glass flask of 20 to 40 cubic centimeters' capacity and allow it to congeal; then, while heating in the hand, observe how the rigid portions act in liquefying. These rigid, crystalline portions should be transparently clear and, being lighter than the fluid portion, float, while liquefying, in the upper layer of the fluid. Hence, if now the fluid be again allowed to congeal, the crystals should appear within the upper half of the oil. The above-mentioned volatile oils partially lack the property of separating a stearoptene in crystals at from 33.8° to 50° F., and though they may have a rose odor, it is not the mild, fragrant odor of genuine rose oil. To recognize the latter, Guibourt makes use of pure concentrated sulphuric acid. Stir together in a watch-crystal an equal number of drops of the oil and of the acid; pure rose oil preserves its characteristic odor, while the foreign oils exhibit a disagreeable odor even when mixed with genuine rose oil.
Schimmel & Co. give a method for an approximate quantitative determination of spermaceti in rose oil: Boil 3 to 5 grammes of stearoptene, separated in the manner above given, with 20 to 25 grammes of 5 per cent. alcoholic potash lye for 5 to 6 hours; then evaporate the alcohol and compound the residue with hot water. In cooling, the greater portion of the stearoptene separates in a crystalline mass upon the surface. Now pour off the alkaline fluid, wash the stearoptene with cold water, then melt it again in hot water, allow it to cool, pour off the water, and repeat the same operations until the wash-water is neutral. The combined aqueous fluids are twice shaken with ether to remove any stearoptene suspended in them. The alcoholic lye separated from the ether is acidulated with dilute sulphuric acid and again extracted with ether. After evaporation no residue (fatty acids) should remain. To control the experiment weigh the regained stearoptene dried at 194° F., adding, of course, the ether used for extracting the alkaline fluid. There will be a small loss, since small quantities of stearoptene always evaporate in drying.
Rosemary oil (oleum rosemarini or ol. anthos) is obtained in Southern Europe, especially in Southern France, Dalmatia and Northern Italy, by distillation from the flowering rosemary, Rosmarinus officinalis, natural order Labiatæ. It is, when fresh, limpid, colorless, or yellowish, of a penetrating, camphor-like odor and taste, and specific gravity 0.880 to 0.915. By age it becomes darker and thickly-fluid. The French rosemary oil is the best and most expensive. It is distinguished from the Italian oil by its much more pleasant odor. Pure French rosemary oil dissolves in an equal part of 90 per cent. alcohol, while the Italian product requires 2 to 3 parts. The cheaper rosemary oils are generally adulterated with oil of turpentine, which is recognized by the oil not dissolving in the above-mentioned proportion in alcohol, as well as by the iodine test. Rosemary oil does not detonate with iodine, but simply dissolves with heating and perhaps the emission of vapors.
The French rosemary oil forms one of the ingredients of eau de Cologne and is used in other perfumery.
Rosewood oil or rhodium oil (oleum ligni rhodii), is obtained by distillation from the wood of the root and lower trunk of Convolvulus scopiarius and C. floridas, L., two plants indigenous to the Canaries. The waste falling off in the manufacture of rosewood beads is chiefly used for the purpose. The oil is of a pale yellow color becoming brown by age. It has a pleasant odor resembling in some slight degree the fragrance of the rose. It is sometimes used in cheap perfumery as a substitute for rose oil.
Sandal-wood oil (oleum ligni sandali) is distilled from the white West Indian or dark yellow East Indian sandal-wood (Santalum myrtifolium). For the purpose of distillation the wood is rasped as finely as possible. The oil obtained from the East Indian wood is the better and more valuable. It has a dark yellow to brown color and a pleasant intense, rose-like odor, while the West Indian oil is pale yellow and of a less agreeable odor. Both oils are very thickly-fluid. The quality and value of sandal-wood oil are best judged by the odor, an adulteration with cedar oil being readily detected thereby.
Sassafras oil (oleum ligni sassafras), from the bruised root of the sassafras tree, Sassafras officinale, natural order Lauraceæ. Sassafras is one of the most widely distributed trees of North America, being found in Canada, in all of the United States, east of the prairies, beyond the Mississippi, and in Mexico. The largest amount of oil distilled is within sixty miles of Baltimore, Md., which is the principal depot for its commerce.
Oil of sassafras varies in color from colorless to yellow and red. Its taste is pungent and aromatic, being agreeable to most persons. It has a pleasant odor resembling that of fennel, and is heavier than water, its specific gravity being 1.08 to 1.09. It is soluble in 4 to 5 parts of alcohol of 0.85 specific gravity, and consists of a mixture of various oils, among which is safrene (C10H16), a dextrorotatory terpene which boils between 311° and 314.6° F. By strongly cooling in a cold mixture, safrol, a crystallizing stearoptene of the composition C10H10O2, is separated. Safrol is the chief constituent of sassafras oil. It is obtained in abundance by cooling, at a temperature of 13° F., the portion boiling between 442.4° and 455° F. It melts at 46.4° F., and at a medium temperature forms a colorless clear oil of pungent taste, characteristic odor, and specific gravity 1.104. When the crystals have been heated to above 158° F., they congeal only after remaining for weeks at a temperature below 32° F., but on being melted at 68° F., the fluid mass again congeals readily on cooling. The safrol is neutral, optically inactive, boils at 449.6° F., and is soluble in alcohol and ether. Sassafras oil is said to be frequently adulterated with oil of turpentine, which is, however, readily detected by the energetic reaction and by distilling a sample of the suspected oil.
Safrol is very suitable for perfuming ordinary soaps. It has in a still higher degree than camphor oil the property of removing the disagreeable odor of some fats, while at the same time it imparts to the soaps an aromatic, refreshing odor. As a rule 8 to 11 ozs. are used for 220 lbs. of soap; but if it shall at the same time serve for removing the disagreeable odor of low quality fats, especially those extracted with bisulphide of carbon or benzine, it is advisable to take 2.2 lbs., or still better, 4.4 lbs. for 220 lbs. of soap. In this case the safrol should be added to the fat after melting and before saponification and thoroughly mixed with it by stirring. An excellent perfume for ordinary soaps is a mixture of safrol and citronella oil, it being at any rate preferable to oil of mirbane.
The standard of value for safrol is its specific gravity, which should not be below 1.104 at 59° F. Specifically lighter kinds contain camphor oil and other impurities.
Thyme oil is obtained in Southern France and Spain by distillation from the flowering thyme, Thymus vulgaris, L. It is greenish-yellow to red (red thyme oil, oleum thymi rubrum), but by rectification becomes colorless (white thyme oil, oleum thymi album). Both oils are quite limpid and possess a strong thyme odor. The specific gravity of the red oil is 0.91 to 0.94, and that of the rectified oil 0.87 to 0.89. The oil prepared from the fresh plant shows, as a rule, a higher specific gravity than that from the dried plant. Thyme oil consists essentially of thymene (C10H16) besides some cymene (C10H14) and thymol (C10H14O), the latter forming an essential constitutent of the oil. Oils from which the thymol has been withdrawn occur in commerce. Pure thyme oil dissolves clear in every proportion in 90 per cent. alcohol; if such is not the case, adulteration with oil of turpentine is probable.
The oil distilled from the field thyme, Thymus serpyllum, L., is limpid, yellowish to gold yellow, and of specific gravity 0.89 to 0.91. Old oil is red or brown and no longer limpid. Good oil is soluble in every proportion in 90 per cent. alcohol and emits only slight vapors when brought in contact with iodine. It consists largely of thymene and cymene, and contains a few per cent. of phenol-like bodies.
Turpentine, oil of.—Under the general name "oil of turpentine" are comprised the volatile oils obtained by distillation from the resins or other portions of different species of the pine. There is a large number of these oils, the most important ones of which shall here be mentioned, though but a few are of interest to the perfumer.
Austrian oil of turpentine, from Pinus laricio, Poir.—It is colorless or yellowish, transparent; specific gravity, 0.864; boiling point, 311° to 314° F.; turns polarized light to the left; soluble in 6 parts 90 per cent. alcohol. When rectified it has a specific gravity of 0.862, and is soluble in 7 parts of 90 per cent. alcohol.
German oil of turpentine, from Pinus sylvestris, P. abies, P. vulgaris, P. picea, and P. rotundata, resembles the former; specific gravity, 0.860 to 0.870; boiling point, 311° to 320° F.; turns polarized light to the left. When rectified it is soluble in 7 parts of 90 per cent. alcohol.
French oil of turpentine, from French turpentine of Pinus maritima.—It is colorless or faint yellowish; specific gravity, 0.860; boiling point, 313° to 315° F.; turns polarized light to the left; odor peculiar; taste burning. With 7 parts of 90 per cent. alcohol it gives a clear solution.
Venetian oil of turpentine, from Venice turpentine of Larix decidua, Mill., is laevorotatory and resembles the preceding, but has a more agreeable odor. Venice turpentine is mostly obtained in Southern Tyrol and in Piedmont, and yields 18 to 25 per cent. of oil.
American oil of turpentine, from American turpentine of Pinus australis, Mich., and P. Taeda, L.—It resembles French turpentine, but turns polarized light to the right. Specific gravity, 0.864; boiling point, 302° to 312.8° F.
Pine oil (oleum abietis) is obtained by distilling with water the leaves or green cones of Pinus picea, L., Abies pectinata, D. C. Its odor is much finer than that of ordinary oil of turpentine. It is soluble in 7 parts of 90 per cent. alcohol.
Dwarf pine oil, Krummholz or Latschenoel (oleum pini pumilionis), is obtained by distilling the young tops and cones of Pinus pumilio with water. It has an agreeable odor, reminding one of juniper; specific gravity, 0.865; boiling point, 338° F. The oil is laevorotatory and soluble in 12 to 15 parts of 90 per cent. alcohol.
Pine-leaf oil is obtained by distilling the leaves of Pinus sylvestris or P. abies by means of steam. It is dextrorotatory; has a fine aromatic odor; boiling point, 320° F.; specific gravity, 0.875 to 0.876.
Templin oil (Kienoel) (oleum pini, ol. templinum) is obtained chiefly in some sections of Switzerland and Tyrol by distilling the wood, branches, leaves, cones, etc., with water. It has a lemon-like odor; specific gravity, 0.860 to 0.880; boiling point, 320° to 327° F., and is laevorotatory.
Balsam-pine oil (oleum abietis canadensis) is obtained in Canada from the branches of Abies balsamea, D. C. It has a slightly yellowish color, a very agreeable and refreshing odor; specific gravity, 0.902; boiling point at 320° to 330.8° F., and turns polarized light to the right.
Of the different varieties of oil of turpentine mentioned only pine oil and dwarf pine oil are used in perfumery.
Oils of turpentine must be kept carefully protected from light and air. When badly kept they gradually become resinous with formation of formic and acetic acids. When exposed to the air oil of turpentine absorbs ozone; with iodine it detonates violently. When brought in contact with a mixture of concentrated sulphuric acid and nitric acid it ignites.
Verbena, oil of, from the lemon verbena, Aloysia citriodora, Hooker. The plant is cultivated in the gardens of Grasse. The oil is extracted from the leaves by distillation in August, but on account of its high price is almost out of market, it being everywhere substituted by the oil of lemon grass, Andropogon citratus.
Violet, oil of.—The perfume of the violet, Viola odorata, natural order Violaceæ, is due to a volatile oil of a green color and of such a penetrating odor as to cause headache; it acquires the agreeable odor of the violet only by strong dilution. The violet farms from whence the flowers are procured for the production of the oil, are very extensive at Nice and in the neighborhood of Florence. The oil is only obtained by the absorption process, all other methods to procure it having failed up to this time. It is scarcely obtainable in commerce, as the French manufacturers, who prepare the greater part of it, use the very small yield for manufacturing fine perfumery.
Vitivert or vetiver oil (oleum iva ranchusa) from the so-called cuscus, the rhizome of an Indian grass, Anathereum muricatum. The oil is obtained by distillation, either from the fresh root in India, or from the imported dried root in Europe. The yield is very small. The oil is thickly-fluid, of a red-brown color, and has an intense, but agreeable odor very much like that of oil of orris root. Like the latter, it possesses the valuable property of diffusing a lasting perfume. Its value can only be judged by the odor, and hence it should only be purchased from a thoroughly reliable firm.
Wintergreen oil (oleum gaultheriæ) is obtained by distillation from the wintergreen, Gaultheria procumbens, a plant common in North America. It is thickly fluid, yellowish green to gold yellow, of a sweetish, aromatic, pungent taste and penetrating, narcotic odor, which becomes agreeable only by strongly diluting the oil. By rectification the oil becomes entirely colorless. Its specific gravity is 1.170 to 1.190 (according to Gladstone, 1.142). It is sparingly soluble in water, but readily so in alcohol, ether, chloroform, etc. The aqueous or dilute alcoholic solution is colored deep violet by ferric chloride.
Wintergreen oil boils at 392° F.; the boiling point, however, soon rises to 431.6° F., when it remains constant. Between 392° and 428° F. a terpene (C10H16) constituting about 1/10 of the oil distils off; the rest corresponds to the composition C8H8O3; it is methyl salicylate