ABOUT AROMATIC SUBSTANCES IN GENERAL.
We apply the term perfume—which really means a fumigating material—to
those substances which make an agreeable impression upon our sense of
smell; the French call them briefly _odeurs_, _i.e._, odors. The high
degree of development at present attained by this industry in France
and England is the cause of the fact that all perfumes are generally
sold under French or English names, which must be borne in mind by
manufacturers in this country.
Perfumes or scents, however, exert not only an agreeable impression
on the olfactory organ, but their effect extends to the entire
nervous system, which they stimulate; when used in excess, they are
apt to cause headache in sensitive persons; the laborers in the
chemical factories where these substances are produced on a large
scale, occasionally even suffer by reason of their stimulating action
on the nerves. For this reason perfumes should never be employed
otherwise than in a very dilute condition; this necessity arises from
a peculiarity of the odorous substances which when concentrated and
pure have by no means a pleasant smell and become fragrant only when
highly diluted. Oil of roses, of orange flowers, or of jasmine, in
fact nearly all aromatic substances, have an almost disagreeable odor
when concentrated; only in an extremely dilute state they yield those
delightful scents which we admire so much in the blossoms from which
they are derived.
It will be easier to understand the almost incredible productiveness
of perfumes if we cite as an instance that a few centigrams of musk
placed on a sensitive scale can for years fill a large hall with their
characteristic odor without showing an appreciable loss of weight, and
still particles must separate from the musk and become evenly diffused
through the air of the hall because the odor is perceptible throughout
every part of it.
It would be an error, however, were we to assume that all aromatic
substances possess the same degree of productiveness; some of them, as
for instance the odorous principle of orris root, have a comparatively
faint smell—a fact which must be borne in mind in the combination of
perfumes. Even odors having a very similar effect on the olfactory
nerves differ widely in their intensity; for instance, true oil (attar)
of roses possesses an intensity more than twice as great as that of the
rose geranium; many authorities agree in giving the proportion as three
to eight, the first figure being that of rose oil, the second that of
oil of rose geranium. Therefore, in order to produce perfumes of equal
intensity (having the same effect on the olfactory nerves), we must
dissolve in an equal quantity of the menstruum either three parts by
weight of the attar of roses or eight parts of the oil of rose geranium.
In the prescriptions for the preparation of perfumes given in this
book, these proportions have been carefully weighed; but it will be the
office of the trained olfactory sense of the manufacturer to modify
them for the various kinds of perfumery in such a way as to produce a
truly harmonious pleasant odor.
Although we know many aromatic substances, we are still in ignorance as
to the preparation of certain decidedly agreeable odors. Thus no one at
present is able to produce the refreshing odor of the sea borne along
on the wind, any more than we are able to reproduce the scent exhaled
by the forest, especially after a warm rain; chemistry, though it has
done much in the domain of perfumery, has thus far thrown no light
upon it. Even certain vegetable odors—for instance, the delightful
perfume exhaled by some Aroideæ and Primulaceæ—we cannot as yet
preserve unchanged in perfumery. This opens an illimitable field for
future activity to the progressive manufacturer.
In a book devoted to the production of perfumes it would certainly
be in place to say something about the physiological relations of
the olfactory sensations; but unfortunately this interesting part
of physiology is still enveloped in great obscurity. All we know
positively on this subject is that many particles of the odorous bodies
evaporate and must come in contact with the olfactory nerves in order
to produce the sensation of odor. There is no lack of experiments
seeking to draw a parallel between sensations of smell and those of
hearing, and, as is well known, we speak of a harmony and dissonance
of odors as we do of tones. Piesse, the renowned perfumer, has even
made an attempt to arrange the different odors in a “harmonic scale”
having the compass of the piano, and to deduce therefrom a law for the
mixture of the several aromatic substances. This attempt, although very
ingenious, still lacks a scientific foundation. Piesse endeavors to
combine the several scents like tones to produce chords in different
scales; the chords of odors are to agree with those of tones. Thus far,
however, no proof has been furnished that the olfactory nerve and the
acoustic nerve have the same organization, and under this supposition
alone could Piesse’s system be accepted as correct.
THE DIVISION OF AROMATIC SUBSTANCES ACCORDING TO THEIR ORIGIN.
The majority of the substances used in perfumery are derived from
the vegetable kingdom, but some come from the animal kingdom, and
for others which do not occur complete in nature we are indebted to
chemistry. As is well known, most blossoms possess a decided odor,
which is extremely fragrant in some; yet it is not the blossoms
alone, but in different genera various parts are distinguished by
agreeable odors. In some plants the fragrant substances are contained
in every part, as in different pines and the mints; in others, only
in the fruits (nutmeg, vanilla), while the other parts are odorless;
in certain plants only the rinds of the fruits contain an aromatic
substance (oranges, lemons). In the Florentine Iris the entire plant is
odorless—only its root stock possesses an agreeable, violet-like scent;
while, for instance, in the camphor-tree an aromatic substance exists
in the wood, in the cinnamon laurel in the bark, in the clove-tree
mainly in the closed buds.
But taking the aromatic plants all together, we find that it is
particularly their flowers which contain the finest odors, and that the
majority of perfumes are prepared from their blossoms.
From the animal kingdom we take for the purposes of perfumery only a
very small number of substances, among which, moreover, some peculiar
relation exists; while, for instance, all men would call the odor of
violets, roses, vanilla, etc., agreeable, the odor of some animal
substances is decidedly obnoxious to many persons, though others like
it—an observation which can be verified often with reference to musk.
With the advancement of science, chemical products find application
in ever increasing numbers; among them are substances which owe their
origin directly to the vegetable kingdom, while others, such as
nitrobenzol and pine-apple ether, are only indirectly derived from it.
From what has been stated, we learn that our attention must be directed
particularly to those scents which are derived from the vegetable
kingdom. To the manufacturer of perfumery, however, it is a matter
of importance whence the plants are obtained which he uses for the
preparation of the odors; a very slight change in the soil often
makes a great difference in the quality of one and the same species;
we see this quite clearly in our ordinary strawberry. While the wild
fruit is but small in size it has a delightful aromatic flavor, and
the same species transplanted into gardens attains much greater size
but possesses only a faint aroma not to be compared with that of the
wild variety. The Lombardian violet is large and beautiful, but the
German has a much more pleasant odor. On the other hand, the blossoms
of the orange-tree obtained from the plants cultivated in pots cannot
be compared with reference to their odor with these growing in the
Riviera, the strip of coast land of the Mediterranean from Marseilles
to Genoa. Altogether the last-named region and the south of France
may be called the true garden of the perfumer; in the neighborhood of
Grasse, Cannes, Nice, Monaco, and some other towns, extensive plots
of ground are set with aromatic plants such as orange-trees, Acacia
farnesiana, jasmine, violets, etc., whose products are elaborated
in large, well-appointed chemical factories solely devoted to the
extraction of their odors. The proximity of the sea-coast, with its
favorable climate almost free from frost, permits the cultivation of
southern plants, while in the more elevated parts of the country the
adjoining Maritime Alps cause a more changeable climate which adapts
them to certain other sweet-scented plants.
The great value of the annual production of the French flower farms at
Cannes, Grasse, and Nice will be evident from the following figures.
The harvesting and elaboration of the flowers at the points named
give employment to fifteen thousand persons, and the average annual
production is:
Orange flowers, 2,000,000 kgm., valued at 2,000,000 francs.
Roses, 500,000 " " 500,000 "
Jasmine, 80,000 " " 200,000 "
Violets, 80,000 " " 400,000 "
Acacia flowers, 40,000 " " 160,000 "
Tuberoses, 20,000 " " 80,000 "
———-———- ———-———-
2,720,000 kgm., valued at 3,340,000 francs.
From these flowers were manufactured: 500,000 kgm. of pomades and
essences, 1,000,000 litres of orange-flower water, 100,000 litres of
rose water, and 1,200 kgm. of oil of roses.
Besides, in more northern countries we find here and there quite
an extensive cultivation of aromatic plants; this is the case, for
instance, in England, where lavender, crisp mint, and peppermint are
planted on a large scale solely for their perfume. In northern Germany,
too, we sometimes find caraway and sweet flag cultivated, for their
peculiar odors only, in special fields.
As stated above, the place of growth of a plant exerts a powerful
influence on the quality of the odors developed in it; this
circumstance may be the reason why certain scents are prized most
highly when they are derived from some definite regions, because
the buyer is sure that the product from such places is of superior
excellence.
Thus we find that English oils of lavender and peppermint are valued
more highly and bring better prices than those from other points of
production; some places even have, as it were, acquired a monopoly of
certain odors. While the factories at Cannes produce the most perfect
odors of roses, orange flowers, jasmine, and cassie, those at Nice
are famous for the finest odors of violet, reseda (mignonette), and
tuberose, and those of Italy for the odors of bergamot and orris root.
Unfortunately there are in the United States no extensive places of
cultivation for odoriferous plants, although certain localities are
very well adapted to the growth of violets, mignonette, roses, syringa,
lavender, etc. Peppermint, however, is grown on a large scale in some
parts of New York State and in Michigan. Of course such an enterprise,
in order to be profitable, requires the intelligent co-operation
of planters and duly qualified chemists, besides well-furnished
laboratories and a considerable amount of capital; but under these
conditions the prospects of gain are good.
At present the manufacturers of perfumery are almost entirely dependent
upon English and French factories for their supply of odors. Owing to
the absence of competition, the prices for the products, excellent
though they are, are high, and become still more so when the crops
are short. These conditions would be materially altered under active
competition.
As indicated above, the odors used in perfumery may be divided into
three distinct groups according to their origin. These groups are:
1. Odors of vegetable origin.
2. Odors of animal origin.
3. Odors of artificial origin—chemical products.
Before describing the preparation of true perfumes, it is necessary
to become acquainted with the several raw materials required in their
manufacture; that is to say, the simple odorous substances, their
origin, their preparation, and their peculiar qualities. Besides these
odorous raw materials, the art of perfumery makes use of a number of
chemical and mineral products, whose quality largely influences that
of the perfume to be made. These, therefore, likewise call for an
appropriate description. Among these auxiliary substances are alcohol,
glycerin, fixed oils, and solid fats, which play an important part
not only in the preparation of the perfumes, but also enter into the
composition of many. The liquid handkerchief perfumes always contain
a large quantity of alcohol, the scented hair oils consist largely
of fixed oils, while solid fats of animal or vegetable origin occur
in the so-called pomades. As we shall see, the actual odors, owing
to their extraordinary productiveness, constitute generally only a
small percentage of the perfumes; the greatest bulk is usually either
alcohol, fixed oil, or solid fat.
Hence, as the last-named substances, aside from the odoriferous
materials, form the foundation of all articles of perfumery, the
manufacturer must devote particular attention to their purity, and
their qualities must be discussed in detail.