synthetic perfume, on the other hand, is
entirely the product of the chemical laboratory, no natural oil or
substance derived therefrom entering into its composition.

The following are among the most important bodies of this class:--

_Amyl salicylate_, the ester prepared from amyl alcohol and salicylic
acid, sometimes known as "Orchidee" or "Trefle". This is much used for
the production of a clover-scented soap. It has the specific gravity at
15 deg. C., 1.052-1.054; optical rotation, +1 deg. 16' to +1 deg. 40'; refractive
index at 20 deg. C., 1.5056; and should contain not less than 97 per cent.
ester, calculated as amyl salicylate.

_Anisic aldehyde_, or _aubepine_, prepared by oxidation of anethol, and
possessing a pleasant, hawthorn odour. This has the specific gravity at
15 deg. C., 1.126; refractive index at 20 deg. C., 1.5693; is optically
inactive, and dissolves readily in one volume of 70 per cent. alcohol.

_Benzyl Acetate_, the ester obtained from benzyl alcohol and acetic
acid. This has a very strong and somewhat coarse, penetrating odour,
distinctly resembling jasmine. Its specific gravity at 15 deg. C. is
1.062-1.065; refractive index at 20 deg. C., 1.5020; and it should contain
at least 97-98 per cent. ester, calculated as benzyl acetate.

_Citral_, the aldehyde occurring largely in lemon-grass and verbena
oils, also to a less extent in lemon and orange oils, and possessing an
intense lemon-like odour. It has a specific gravity at 15 deg. C.,
0.896-0.897, is optically inactive, and should be entirely absorbed by a
hot saturated solution of sodium bisulphite.

_Citronellal_, an aldehyde possessing the characteristic odour of
citronella oil, in which it occurs to the extent of about 20 per cent.,
and constituting considerably over 90 per cent. of eucalyptus citriodora
oil. Its specific gravity at 15 deg. C. is 0.862; refractive index at 20 deg.
C., 1.447; optical rotation, +8 deg. to +12 deg.; and it should be entirely
absorbed by a hot saturated solution of sodium bisulphite.

_Coumarin_, a white crystalline product found in Tonka beans, and
prepared synthetically from salicylic acid. It has an odour resembling
new-mown hay, and melts at 67 deg. C.

_Geraniol_, a cyclic alcohol, occurring largely in geranium, palma-rosa,
and citronella oils. Its specific gravity at 15 deg. C. is 0.883-0.885;
refractive index at 20 deg. C., 1.4762-1.4770; it is optically inactive, and
boils at 218 deg.-225 deg. C.