French.—Specific gravity at 15° C., 0.91-0.933; slightly lævo-rotatory up to -4°, but usually too dark to observe; phenols, by absorption with 10 per cent. aqueous caustic potash, 25-55 per cent.; refractive index at 20° C., 1.490-1.500; soluble in 1-1.5 volumes of 80 per cent. alcohol.
Spanish.—Specific gravity at 15° C., 0.955-0.966; optical rotation, slightly lævo-gyrate; phenols, 70-80 per cent.; refractive index at 20° C.; 1.5088-1.5122; soluble in 2-3 volumes of 70 per cent. alcohol.
In addition to the phenols, thymol or carvacrol, these oils contain cymene, thymene and pinene.
The white thyme oil is produced by rectifying the red oil, which is generally effected at the expense of a considerable reduction in phenol content, and hence in real odour value of the oil.
Verbena Oil.—The oil usually sold under this name is really lemon-grass oil (which see supra). The true verbena oil or French verveine is, however, occasionally met with. This is distilled in France from the verbena officinalis, and has the following properties: Specific gravity at 15° C., 0.891-0.898; optical rotation, slightly dextro- or lævo-rotatory; aldehydes, 70-75 per cent.; soluble in 2 volumes of 70 per cent. alcohol.
The oil contains citral.
Vetivert oil, distilled from the grass, Andropogon muricatus, or Cus Cus, and grown in the East Indies.
Specific gravity at 15° C., 1.01-1.03; optical rotation, +20° to +26°; saponification number, 15-30; refractive index at 20° C., 1.521-1.524; soluble in 2 volumes of 80 per cent. alcohol.
The price of this oil makes its use prohibitive except in the highest class soaps.
Wintergreen Oil.—There are two natural sources of this oil, the Gaultheria procumbens and the Betula lenta. Both oils consist almost entirely of methyl salicylate and are practically identical in properties, the chief difference being that the former has a slight lævo-rotation, while the latter is inactive.