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.

There is a considerable distinction, however, often lost sight of,
between an _artificial_ and a _synthetic_ oil. An artificial oil may be
produced by separating various constituents from certain natural oils,
and so blending these, with or without the addition of other substances,
as to produce a desired odour, the perfume being, at any rate in part,
obtained from natural oils. A