Oleum Aurantii. U. S. Oil of Orange.

Ol. Aurant. [Oleum Aurantii Corticis, U. S. VIII. Orange Oil, Oil of Sweet Orange]

Related entry: Orange - Oil of Orange Flowers

"A volatile oil obtained by expression from the fresh peel of sweet orange, Citrus Aurantium sinensis Gallesio (Fam. Rutaceae), and its varieties. Preserve it in small, well-stoppered, amber-colored bottles, in a cool place, protected from light. Oil of Orange having a terebinthinate odor is not to be dispensed." U. S.

Oleum Aurantiorum; Essential Oil of Orange Peel, Essence of Orange; Huile volatile d'Orange, Fr. Cod.; Apfelsinenschalenöl, Pomeranzenschalenöl, G.; Essenza di arancio amara, Ensenza delta corteccia. It.

This oil is used only for flavoring purposes, and has been introduced principally because of its employment in elixirs and in Spiritus Aurantii Compositus.

Oil of orange is prepared in Calabria and Sicily in three ways: 1, by scraping off the exterior part of the rind and submitting it to expression; 2, by putting the scrapings into hot water, depressing the pulp beneath, and skimming off the oil as it rises; 3, by distillation. The best Sicily orange oil is procured by dexterous compression, within a cask, of the fresh rind by the hand, the oil being driven out in jets. It is sometimes absorbed by a sponge. (A. J. P., 1868.) It is largely made at Messina, and in the south' of France. It is also extracted by the ecuelle process, and partly from the Bigarade and partly from the sweet or Portugal orange, the scarcely ripe fruit being in either case employed. The oil made from the former is much more valuable than that obtained from the latter, and the two are distinguished in price-currents as Essence de Bigarade and Essence de Portugal.

Under the name of Oleum Aurantii Amari (Oil of Bitter Orange), the National Formulary IV has introduced the oil of bitter orange, which it defines as "a volatile oil obtained by expression from the fresh peel of the bitter orange, Citrus Aurantium amara Linné (Fam. Rutaceae). Preserve it in small, well-stoppered, amber-colored bottles, in a cool place, protected from light. Oil of Bitter Orange having a terebinthinate odor is not to be dispensed." N. F. IV.

The description is as follows: "Oil of Bitter Orange is a pale yellow liquid, having the characteristic, aromatic odor of the Seville orange, and an aromatic somewhat bitter taste. Soluble in 4 volumes of alcohol, the solution being neutral to litmus paper. " N. F. IV.

This oil is supposed to have a more delicate odor than the oil from the sweet orange.

Properties.—Oil of orange peel consists, as has been shown by Wallach, of d-limonene to the extent of at least 90 per cent.; of the remainder, about 5 per cent. are the odorous constituents, among which are citral, traces of citronellal, and the methyl ester of anthranilic acid. The inner thick part of the rind contains also a bitter principle, called hesperidin, discovered by Lebreton in 1828, but more fully studied by Hoffmann (Ber. d. Chem. Ges., 1876, pp. 26, 685). It is best prepared from the unripe bitter orange. Its formula is C22H25O12, and it is a glucoside, as is shown by the reaction with diluted sulphuric acid, whereby it is decomposed into hesperetin, C16H14O6, and glucose, C6H12O6.

A waxy non-volatile substance is present in oil of orange, which interferes-with the transparency of solution made with 90 per cent. alcohol. This oil is one of the most difficult to preserve. A method for its preservation, which we have used for years, is to shake the oil briskly with one-eighth of its volume of distilled water, and allow it to separate, then remove the essential oil, filter rapidly if necessary, and mix the filtered oil with 95 per cent. alcohol in the proportion of one volume of the oil to seven volumes of alcohol.

It may be preserved indefinitely by adding 10 per cent. of its volume of olive oil.

The oil of orange is used chiefly as a flavoring agent but Zickgraf (M. M. W., 1910, lvii, p. 1070) speaks very highly of its effect in chronic bronchitis for the same class of cases in which oil of turpentine is used. It has the advantages over the latter of being much more pleasant to take and non-irritant to the kidneys.

Dose, three to five minims (0.2-0.3 mil).

Off. Prep.—Elixir Aromaticum (from Spirit), U. S.; Spiritus Aurantii Compositus, U. S.; Elixir Cardamomi Compositum (from Compound Spirit), U. S.; Elixir Vanillini Compositum (from Compound Spirit), N. F.; Spiritus Cardamomi Compositus, N. F.; Spiritus Myrciae Compositus, N. F.; Spiritus Vanillini Compositus, N. F.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.