Oleum Foeniculi. U. S. Oil of Fennel.
Ol. Foenic. [Fennel Oil]
Related entries: Foeniculum
"A volatile oil distilled from the ripe fruit collected from cultivated varieties of Foeniculum vulgare Miller (Fam. Umbelliferae). If wholly or partly solidified, carefully warm the Oil until liquefied and thoroughly mix it before dispensing. Preserve it in well-stoppered, amber-colored bottles, in a cool place, protected from light." U.S.
Huile volatile de Fenoutt, Fr. Cod.; Essence de Fenouil, Fr.; Oleum Foeniculi, P. G.; Fenchalol, G.
Fennel seeds yield about 2.5 per cent., or, according to Zeiler, from 3.4 to 3.8 per cent., of oil. That used in this country is imported. "A colorless or pale yellow liquid, having the characteristic odor and taste of fennel. It is soluble in 8 volumes of 80 per cent. alcohol and in 1 volume of 90 per cent. alcohol, forming a solution neutral to litmus. Specific gravity: 0.953 to 0.973 at 25° C. (77° F.). The optical rotation varies from +12° to 4- 24° in a 100 mm. tube at 25° C. (77° F.). When tested by the method under Oleum Anisi, with the following modifications, the congealing point of the Oil does not fall below 3° C. (37.4° F.). Cool the test tube containing the 10 mils of Oil of Fennel in a freezing mixture until the temperature has fallen to 0° C. (32° F.), and induce crystallization as directed." U. S.
It congeals below 10° C. (50° F.) into a crystalline mass, separable by pressure into a solid and a liquid portion, the former heavier than water, and less volatile than the latter, which rises first when the oil is distilled. It contains anethol, C10H12O (a phenol-ether forming a white solid melting at 21° C. (69.8° F.)) (see Oleum Anisi), the latter usually in amounts of about 60 per cent., d-pinene, phellandrene, dipentene, fenchone, C10H16O (a liquid ketone), chavicol, anisic aldehyde, and anisic acid. Fenchone is the constituent which when present gives the disagreeable bitter taste to many of the commercial oils. Schimmel's Report for April, 1897, mentions limonene as also at times present as a constituent. Umney finds that Japanese oil contains about 75 per cent. of anethol and 10 per cent. of fenchone, besides terpenes. (Proc. A. Ph. A., 1897, 516.) There is reason to believe that much of the commercial oil is adulterated with oil from which the anethol or crystalline constituent has been separated; the official solidifying point not below 5° C. (41° F.) should be required. Fluckiger states (Pharm. Chem., 2d ed., 1888, 422) that it contains more hydrocarbon than oil of anise, and notably that from Nimes, in Southern France, contains much less anethol, and hence has a milder and sweeter taste which is also probably due to the absence of the bitter fenchone. As found in commerce, therefore, the oil of fennel is not uniform, and a specimen examined by Montgomery did not congeal at -5.5° C. (22° F.).
Dose, three to five minims (0.2-0.3 mil).
Off. Prep.—Aqua Foeniculi; U. S.