Oleum Bergamottae (U. S. P.)—Oil of Bergamot.
Related entries: Aurantii Amari Cortex (U. S. P.)—Bitter Orange Peel - Aurantii Dulcis Cortex (U. S. P.)—Sweet Orange Peel - Aurantii Flores.—Orange Flowers - Limon.—Lemon - Oleum Aurantii Corticis (U. S. P.)—Oil of Orange Peel
"A volatile oil obtained by expression from the rind of the fresh fruit of Citrus Bergamia, Risso et Poiteau (Nat. Ord.—Rutaceae). It should be kept in well-stoppered bottles, in a cool place, protected from light"—(U. S. P.).
SYNONYM: Oleum bergamii (Pharm., 1880).
Botanical Source, Preparation, and History.—Oil of bergamot exists in the rind of the ripe fruit of Citrus Bergamia, from which it may be obtained by expression in the same manner as for procuring the oil of lemon. It may also be obtained by distillation, but the product is not so agreeable as by expression. According to Wight and Arnott, the leaves of the bergamot tree are oblong, more or less elongated, acute, or obtuse, underside somewhat pale; the petiole more or less winged or margined; the flowers usually small and white; the fruit pale-yellow, pyriform or depressed; the rind with concave receptacles of oil; the pulp more or less acid. About 21 ounces of oil may be obtained by expression from 100 bergamots. The plant is cultivated in the south of Europe from whence the oil is imported.
Description and Tests.—Bergamot oil is sometimes erroneously called essence of bergamot. The U. S. P. describes it as "a greenish or greenish-yellow, thin liquid, having a peculiar, very fragrant odor, and an aromatic, bitter taste. Specific gravity, 0.880 to 0.885 at 15° C. (59° F.). Its optical rotation should not be more than 20° to the right in a 100 Mm. tube, and at a temperature of about 15° to 20° C. (59° to 68° F.). Two volumes of the oil, when mixed with 1 volume of alcohol, should give a clear solution of a slightly acid reaction, and this solution should not become turbid on the further addition of alcohol (distinction from oil of orange or oil of lemon). The oil should also be soluble at 20° C. (68° F.), without the separation of oily drops, in 1.5 to 2 volumes of alcohol of 80 per cent by volume. It is soluble, in all proportions, in glacial acetic acid. If about 2 Gm. of the oil be evaporated in a small, tared capsule, on a water-bath, until the odor has completely disappeared, a soft, green, homogeneous residue should be left, amounting to not more than about 6 per cent of the oil (absence of fatty oils)" —(U. S. P.)
Chemical Composition.—The fragrance of oil of bergamot is due to the acetic ester of laevo-linalool, its quantity varying in the oil from 36 to sometimes 40 per cent. The fully matured fruits yield most of this ester. Furthermore, free linalool, dextro-limonene, perhaps dipentene, and 5 per cent of inodorous bergamot camphor or bergapten (C12H8O4) are present. According to Pomeranz (1891), it is the mono-methyl-ether of dioxy-coumarin, derived from phloroglucin (Gildemeister and Hoffmann, loc. cit.).
Action and Medical Uses.—Gently excitant, but is used almost wholly in perfumery, soaps, and for scenting toilet preparations and ointments.
Related Oils.—OIL OF LEMON GRASS, Oleum andropogon citrati. An essential oil, sometimes called oil of verbena, derived from several species of Andropogon, particularly Andropogon citratus, cultivated in India, Ceylon, Malayan peninsula, and near Singapore. It is yellowish-brown with a sharp taste and peculiar odor, used only in perfumes in this country, but as a stimulant and carminative in the East. When treated with a saturated solution of sodium bisulphite, it yields a crystalline compound. The known constituents of this oil are the aldehyde citral (C10H16O), an unsaturated ketone methyl-heptenone (C8H14O), and in the highest boiling fractions the alcohol geraniol (C10H18O).
OIL OF CITRONELLA, Oleum andropogon nardi.—The volatile oil distilled from a plant in cultivation in Ceylon, in the Straits Settlement, and coast of Malabar. The natives of Ceylon are engaged in the treatment of the plant, which is distilled by steam in suitable apparatus. It is a yellowish-green oil, slightly laevo-rotatory, of the specific gravity 0.886 to 0.900, has a sharp taste and characteristic odor. With alcohol, it mixes in all proportions. Two or two and one-half volumes of alcohol (80 per cent) should mix perfectly transparent with 1 volume of the oil, at a temperature not lower than 20° C. (68° F.). If the mixture be cloudy it indicates the presence of fixed oils. If oily drops form upon standing, when 5 to 10 volumes of 80 per cent alcohol are added, the presence of petroleum is indicated. Citronella oil contains about 50 per cent of geraniol, citronellal, an aldehyde (C10H18O) which Semmler (1891) succeeded in converting into citronellic acid (C10H18O2); furthermore borneol (1 to 2 per cent), methyl-heptenone, acetic and valerianic acids in the form of esters. The higher specific gravity observed in Lana batu oil is due to the presence of methyl-eugenol (allyl-veratrol C6H3.C3H5.OCH3.OCH3) (Gildemeister and Hoffmann, loc. cit.). The oil is employed in perfuming soaps.
YLANG-YLANG OIL, Cananga oil, Oleum unonae, Oleum anonae.—The flowers of a South Asiatic tree, growing in Java and Manila, yield this essential oil which is used only in perfumes. A reputed solution of it, in the oil of the cocoanut, is known as Macassar Hair Oil. Ylang-Ylang oil contains laevo-linalool, geraniol, benzoic and acetic acids (in the form of esters), methyl-ether of para-kresol (CH3.C6H4.OCH3), traces of a phenol, cadinene, etc.
