rs to be usually
manufactured from eugenol, a phenol contained in oil of cloves.
Piperonal, an aldehyde closely allied to vanillin, is used in
perfumery under the name of heliotropin and is prepared from oil
of sassafras and oil of camphor. Cumarine, the material to which
tonka bean, sweet woodruff, and new-mown hay owe their
characteristic odors, was synthetically prepared by W.H. Parkin
in 1868 by heating sodiosalicylic aldehyde with acetic anhydride,
though now more cheaply prepared from an herb growing in Florida.
Irone, which has the perfume of violets, was isolated in 1893
from a ketone contained in orris-root; and ionone, another ketone
which has a very closely similar odor of fresh violets and was
isolated after some years' further work, is largely used in the
preparation of violet perfume. Irone and ionone are closely
similar in composition to oil of turpentine which when taken into
the body is partly converted into perfume and gives a strong odor
of violets to the urine. "Little has yet been accomplished toward
ascertaining the relation between the odor and the chemical
constitution of substances in general. Hydrocarbons as a class
possess considerable similarity in odor, so also do the organic
sulphides and, to a much smaller extent, the ketones. The
subject waits for some one to correlate its various
physiological, psychological and physical aspects in the same way
that Helmholtz did for sound. It seems, as yet, impossible to
assign any probable reason to the fact that many substances have
a pleasant odor. It may, however, be worth suggesting that
certain compounds, such as the volatile sulphides and the
indoles, have very unpleasant odors because they are normal
constituents of mammalian excreta and of putrefied animal
products; the repulsive odors may be simply necessary results of
evolutionary processes." (_Loc. cit._, _Nature_, December 27,
1900.)

Many of the perfumes in use are really combinations of a great
many different odors in varying proportions, such as oil of rose,
lavender oil, ylang-ylang, etc. The most highly appreciated
perfumes are often made up of elements which in stronger
proportion would be regarded as highly unpleasant.

In the study and manufacture of perfumes Germany and France have
taken the lead in recent times. The industry is