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 deg. C., 0.891-0.898; optical rotation, slightly dextro- or laevo-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 deg. C., 1.01-1.03; optical rotation, +20 deg. to +26 deg.; saponification number, 15-30; refractive index at 20 deg. 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 laevo-rotation, while the latter is inactive. Specific gravity at 15 deg. C., 1.180-1.187; optical rotation, Gaultheria oil, up to -1 deg., Betula oil, inactive; ester as methyl salicylate, at least 98 per cent.; refractive index at 20 deg. C., 1.5354-1.5364; soluble in 2-6 volumes of 70 per cent. alcohol. Besides methyl salicylate, the oil contains triaconitane, an aldehyde or ketone, and an alcohol. _Ylang-ylang oil_, distilled from the flowers of Cananga odorata, the chief sources being the Philippine Islands and Java. Specific gravity at 15 deg. C., 0.924-0.950; optical rotation, -30 deg. to -60 deg., and occasionally higher; refractive index at 20 deg. C., 1.496-1.512; ester, calculated as linalyl benzoate, 27-45 per cent., occasionally up to 50 per cent.; usually soluble in 1/2 volume of 90 per cent. alcohol. The composition of the oil is qualitatively the same as that of Cananga oil, but it is considerably more expensive and therefore can only be used in the highest grade soaps. _Artificial and Synthetic Perfumes._ During the past few years the constitution of essential oils has been studied by a considerable number of chemists, and the composition of many oils has been so fully determined that very good imitations can often be made at cheaper prices than those of the genuine oils, rendering it possible to produce cheap soaps having perfumes which were formerly only possible in the more expensive article.