_Patchouli oil_, distilled from the leaves of Pogostemon patchouli, a herb grown in India and the Straits Settlements. Specific gravity at 15 deg. C., 0.965-0.990; optical rotation, -45 deg. to -63 deg.; refractive index at 20 deg. C., 1.504-1.511; saponification number, up to 12; sometimes soluble in 0.5 to 1 volume of 90 per cent. alcohol, becoming turbid on further addition. The solubility of the oil in alcohol increases with age. The oil consists to the extent of 97 per cent. of patchouliol and cadinene, which have little influence on its odour, and the bodies responsible for its persistent and characteristic odour have not yet been isolated. _Peppermint oil_, distilled from herbs of the Mentha family, the European and American from Mentha piperita, and the Japanese being generally supposed to be obtained from Mentha arvensis. The locality in which the herb is grown has a considerable influence on the resulting oil, as the following figures show:-- English.--Specific gravity at 15 deg. C., 0.900-0.910; optical rotation, -22 deg. to -33 deg.; total menthol, 55-66 per cent.; free menthol, 50-60 per cent.; soluble in 3-5 volumes of 70 per cent. alcohol. American.--Specific gravity at 15 deg. C., 0.906-0.920; optical rotation, -20 deg. to -33 deg.; total menthol, 50-60 per cent.; free menthol, 40-50 per cent. The Michigan oil is soluble in 3-5 volumes of 70 per cent. alcohol, but the better Wayne County oil usually requires 1-2 volumes of 80 per cent. alcohol, and occasionally 0.5 volume of 90 per cent. alcohol. French.--Specific gravity at 15 deg. C., 0.917-0.925; optical rotation, -6 deg. to -10 deg.; total menthol, 45-55 per cent.; free menthol, 35-45 per cent.; soluble in 1 to 1.5 volumes of 80 per cent. Japanese.--Specific gravity at 25 deg. C., 0.895-0.900; optical rotation, laevo-rotatory up to -43 deg.; solidifies at 17 to 27 deg. C.; total menthol, 70-90 per cent., of which 65-85 per cent. is free; soluble in 3-5 volumes of 70 per cent. alcohol. The dementholised oil is fluid at ordinary temperatures, has a specific gravity of 0.900-0.906 at 15 deg. C., and contains 50-60 per cent. total menthol. Some twenty different constituents have been found in American peppermint oil, including menthol, menthone, menthyl acetate, cineol, amyl alcohol, pinene, l-limonene, phellandrene, dimethyl sulphide, menthyl isovalerianate, isovalerianic aldehyde, acetaldehyde, acetic acid, and isovalerianic acid. _Peru balsam oil_, the oily portion (so-called "cinnamein") obtained from Peru balsam. Specific gravity at 15 deg. C., 1.100-1.107; optical rotation, slightly dextro-rotatory up to +2 deg.; refractive index at 20 deg. C., 1.569 to 1.576; ester, calculated as benzyl benzoate, 80-87 per cent.; soluble in 1 volume of 90 per cent. alcohol. The oil consists chiefly of benzyl benzoate and cinnamate, together with styracin, or cinnamyl cinnamate, and a small quantity of free benzoic and cinnamic acids.