Oleum Cedri. Cedar Wood Oil.
Synonym.—OIL OF RED CEDAR.
Cedar wood oil is obtained by distillation from the wood of the red cedar, Juniperus virginiana, Linn. (N.O. Coniferae), and other species, the first-named being a North American plant, in which the oil exists to the extent of 2.5 to 4.5 per cent. It occurs as an almost colourless or slightly yellow, somewhat viscid liquid, occasionally containing crystals of cedar camphor, and having a mild but persistent, characteristic odour. Specific gravity, 0.940 to 0.950. Rotation, -30° to -45°. Refractive index, 1.505 at 17°. An inferior oil is obtained in America as a by-product in drying lead pencils; it contains only the more volatile portions of the natural oil, and has a lower specific gravity than the latter.
Soluble in alcohol, with difficulty (1 in 10 to 20).
Constituents.—The oil consists almost entirely of cedrene, a liquid sesquiterpene (C15H24), which can be separated by fractional distillation, boiling at 261° to 262°; specific gravity, 0.9359, rotation, -60°. It may also contain a solid substance, cedar camphor or cedrol (C15H26O), having the characteristics of a tertiary alcohol, melting at 74°, boiling at 282°. Cedrol, however, is not invariably present in the oil.
Action and Uses.—Cedar wood oil has been recommended for use in place of oil of sandal wood in gonorrhoea, but is rarely so employed. It is used for its odour in perfumery, and is also used in microscopy with oil-immersion lenses, being thickened for this purpose, probably with Canada turpentine, so that its index of refraction is 1.52.