285. Oleum Bergamottae.—Oil of Bergamot.
285. OLEUM BERGAMOTTAE.—OIL OF BERGAMOT. A volatile oil obtained by expression from the rind of the fresh fruit of Cit'rus berga'mia Risso et Poiteau, the fruit being collected in November or December, still greenish, unripe, but full grown. By some, the bergamot orange is supposed to be an established hybrid—a product of cultivation. A greenish or greenish-yellow, thin liquid, having a peculiar, very fragrant odor, and an aromatic, bitter taste. The color is due to chlorophyll. It is distinguished from the oils of orange and lemon by forming a clear solution with solutions of potassium. This oil, so valuable in perfumery, was official in the U.S.P. of 1890, but was dropped from the list in 1900.
CONSTITUENTS.—By fractional distillation there comes over as the first fraction at 60° to 65° about 40 per cent. of the oil. This has a lemon odor and consists of almost pure limonine. The second fraction (10 per cent.), distilling at 77° to 82°, consists principally of dipentene, C10H16. The third fraction of about 25 per cent., distilling between 87° and 91°, consists of linalool, C10H18O. The fourth fraction, 90° to 105° (approximately 20 per cent.), having the pronounced bergamot odor, consists of linalool (linalyl) acetate, C10H17OC2H3O. It is to this that the peculiar odor of bergamot is probably due.