Botanical: Pogostemon patchouli (PILL.)
Family: N.O. Labiatae
—Description—This fragrant herb, with soft, opposite, egg-shaped leaves and square stems, grows from 2 to 3 feet in height, giving out the peculiar, characteristic odour of patchouli when rubbed. Its whitish flowers, tinged with purple, grow in both axillary and terminal spikes. The crop is cut two or three times a year, the leaves being dried and packed in bales and exported for distillation of the oil. The best oil is freshly distilled near the plantations. That obtained from leaves imported into Europe, often damaged and adulterated even up to 80 per cent, is inferior. It is used in coarser perfumes and in ‘White Rose’ and ‘Oriental’ toilet soaps. Although the odour is objectionable to some, it is widely-used both in Asia and India. Sachets are made of the coarsely-powdered leaves, and before its common use in Europe, genuine Indian shawls and Indian ink were distinguished by the odour, which has the unusual quality of improving with age. Hence the older oil is preferred by perfumers and used to confer more lasting properties upon other scents.
—Constituents—Oil of Patchouli is thick, the colour being brownish-yellow tinted green. It contains coerulein, the vivid blue compound found in matricaria, wormwood and other oils. It deposits a solid, or stearoptene, patchouli alcohol, leaving cadinene.
It is laevorotatory, with the specific gravity of 0.970 to 0.990 at 15 degrees C. (59 degrees F.).
The inferior oil of Assam is from Microtoena cymosa.
Cubeb and cedar oils are said to be usual adulterants.