Oil of Bergamot.
Related entries: Oil of Lemon
Oil of Bergamot. N. F. IV (U. S. 1890). Oleum Bergamottae. Oleum Bergamii. U. S. 1880.—"A volatile oil obtained by expression from the rind of the fresh fruit of Citrus Aurantium Bergamia (Risso et Poiteau) Wight et Arnott (Fam. Rutaceae), and containing not less than 36 per cent. of ester, calculated as linalyl acetate. Preserve It in small, amber-colored, well-stoppered bottles in a cool place, protected from light." N. F.
The bergamot tree has oblong-ovate, dentate, acute, or obtuse leaves, somewhat paler on the under than on the upper surface, and with footstalks more or less winged or margined. The flowers are white, and usually small; the fruit is pyriform or roundish, about three inches in diameter, terminated by the remains of the short style, with concave receptacle of oil in the rind. The pulp of the fruit is sourish, somewhat aromatic, and not disagreeable. The rind is shining, and of a pale-yellow color, and abounds in a very grateful volatile oil. This may be obtained by expression or distillation. In the former cage it preserves the agreeable flavor of the rind, but is somewhat turbid; in the latter it is limpid but less sweet. The mode of procuring it by expression is exactly the same as that used for oil of lemon. (See Oleum Limonis.) It is brought from Italy, the south of France, and Portugal.
"Oil of Bergamot is a green or greenish-yellow liquid, neutral or only faintly acid, having a characteristic fragrant odor and an aromatic bitter taste.
"Two volumes of the oil, when mixed with 1 volume of alcohol, give a clear solution and this does not become turbid on the further addition of alcohol. It is soluble in 2 volumes of 80 per cent. alcohol with not more than a slight cloudiness, and no separation of oil globules. Also soluble in all proportions in glacial acetic acid.
"Specific gravity: 0.875 to 0.880 at 25° C. (77° F.).
"It is dextrorotatory, the angle of rotation varying from + 8° to + 24°, in a 100 mm. tube, at25°C. (77° F.).
The oil of bergamot, often called essence of bergamot, has a sweet, very agreeable odor, a bitter, aromatic, pungent taste, a pale greenish-yellow color, and a slightly acid reaction.
It contains limonene, dipentene, linalool, a solid greasy compound called bergaptene, or bergamot camphor, and linalool acetate, C10H17.C2H3O2, which latter makes up about 40 per cent. of the expressed oil, but is decomposed in large part by the process of steam distillation. Bergaptene has been very fully studied by Pomeranz. (M. Chem., 1891, 379.) It melts at 188° C. (370.4° F.), and has the composition C12H8O4, being the lactone or inner anhydride of bergaptenic acid, C12H10O5. By fusion with potassium hydroxide, bergaptene yields phloroglucin. (See Schim. Rep., April, 1893, and 1895, 24; also Proc. A. Ph. A., 1897, 630.) The oil is distinguished from lemon and orange oils by readily dissolving in solution of potassium hydroxide and forming with it a clear solution. (Zeiler.) Though possessed of the stimulant properties of the volatile oils in general, it is employed chiefly as a perfume.
According to Galewsky (Ph. Ztg., 1915, Ix, p. 55) the oil of bergamot is an extraordinarily active insecticide and useful to protect the body against lice and other vermin.
It is often adulterated. (See C. D., 1908, 383; also 1910, 52.)