Essential oil of camphor is obtained as a by-product in the manufacture of camphor from the camphor laurel, Cinnamomum Camphora, T. Nees and Eberm. (N.O. Laurineae), a large tree indigenous to Formosa, Japan, and China. It occurs as a colourless or yellowish liquid, having the odour of camphor. Its properties and composition are very variable, largely on account of the more or less complete separation of the camphor and safrol, and fractionation. No definite standards can be given. Specific gravity, after the removal of safrol, about 0.960. The oil is dextrorotatory.
Constituents.—The natural oil contains safrol, acetaldehyde, camphor, terpineol, eugenol, cineol, d-pinene, phellandrene, dipentene, and cadinene. The heavy fractions of the oil are valuable as the source of safrol, which is used in large quantities in the preparation of synthetic heliotropin. These have a specific gravity of 1.000 to 1.025. The lighter fractions, which usually consist of nothing but terpenes, are used as a solvent of resins, and as a substitute for turpentine. They have a specific gravity of 0.890 to 0.920 and an optical rotation of +16° to +30°.
Action and Uses.—Essential oil of camphor is employed as a rubefacient and mild counter-irritant to rheumatic and inflamed joints. It may be applied undiluted, or mixed with an equal quantity of olive oil. It is also used as a parasiticide.
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.