Active Ingredients. - The flowers contain volatile oil (called oil of Neroli), bitter extractive, and other substances. The water prepared from them should be colorless and fragrant. The rudimentary and, of course, unripe fruits contain volatile oil, a bitter extractive (hesperidine), bitter astringent matter, and citric and malic acid. The rind of the ripe fruit contains volatile oil, isomeric with oil of turpentine (C10H16), hesperidine, and a little gallic acid. The juice of the ripe fruit contains citric acid, malic acid, mucilage, albumen, sugar, citrate of lime, and water.

Physiological Action. - M. Imbert-Gourbeyre states that in the south of France, where the orange is largely cultivated for the sake of the rind, the persons who are engaged in removing it are affected in a singular manner. Their hands become inflamed with an erythematous, a papular, or a vesicular eruption; they suffer from headache, dizziness, tinnitus aurium, deafness, neuralgia, oppression in breathing, constriction of the throat, nausea, pyrosis, irritation, and thirst. They are disturbed by dreams; they experience cramps and twitchings of the muscles; and, occasionally, convulsions of an epileptic character. These symptoms continue only so long as the occupation is pursued. Like other substances of an aromatic nature, orange-peel produces in the stomach a grateful sense of warmth.

Therapeutic Action. - Orange-peel stimulates the digestive system, and is valuable as qualifying the action of other bitters in the treatment of dyspepsia. It is usually employed as a cover for the taste of quinine, and as an associate with purgative medicines of a griping character, or when the bowels are distended with flatus. M. Imbert-Gourbeyre states that he has successfully employed the essential oil for hysterical and other nervous affections. In certain febrile inflammatory complaints, orange-juice allays thirst and diminishes preternatural heat.

Preparations. - Aqua Aurantii Florum; Syrupus Aurant. Flor.; Syr. Aurant. Corticis; Confectio Aurant. Cort.