THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[November 1G, 1872. 
384 
products yield identical "bodies in identical proportions ; 
namely, for each molecule of essence, ten atoms of car¬ 
bon and sixteen atoms of hydrogen. This is indicated 
by their common formula C 10 H 16 . These facts concern¬ 
ing isomerism prove that the qualities of the bodies de¬ 
pend much more upon the internal arrangement and 
deportment of their smallest parts, inaccessible to our 
investigations, than even upon the nature of their 
matter, and show how far we yet are from having pene¬ 
trated into the first conditions of the activity and 
energy of matter. 
Among the odoriferous essences which are ranged by 
chemists in the class of aldehydes, may be mentioned 
mint, rue, bitter almonds, cummin, anise, fennel, canella, 
and meadow-sweet. Finally, others are placed in the 
series of ethers, which are very varied and complex, 
notwithstanding the constant simplicity of their pri¬ 
mary elements. 
Such is the chemical nature of the greater part of 
the odorous principles of vegetable origin. But che¬ 
mistry has not been limited to establishing the internal 
constitution of these substances ; it has been able to re¬ 
produce artificially a certain number of them, and the 
compounds so fabricated in the laboratory, are in every 
respect absolutely identical with the products extracted 
from the plant. The theoretical speculations on the ar¬ 
rangement of atoms, which are sometimes alleged to be 
useless, contribute not only to make natural laws better 
known, but they also frequently, as is shown in the pre¬ 
sent example, give the key to unlock brilliant and valu¬ 
able inventions. An Italian chemist, Piria, while work¬ 
ing in Paris, in 1838, was the first to reproduce a natu¬ 
ral aromatic principle. He prepared, by means of 
reagents indicated by theory, a salicylic aldehyde, which 
he found to be essence of meadow-sweet (Sjrircca 
ubnaria). Some years afterwards, in 1843, M. Cahours 
discovered methylsalicylic ether, and showed that it was 
identical with the essence of wintergreen (Gaultheria 
procumbeus). The following year Wertheim obtained 
the essence of mustard in preparing allylsulphocyanic 
ether. These discoveries made a great sensation. At 
the present day chemists possess the means of preparing 
many other natural essences. Ordinary camphor, and 
the essences of bitter almonds, cummin, and canella, 
which we have seen to be aldehydes, are prepared with¬ 
out the camphor-tree, almonds, cummin, or canella. 
Besides these ethers and aldehydes, of which the 
identity with the essences of vegetable origin has been 
demonstrated, there exists among the new compounds of 
organic chemistry, a certain number of products formed 
by the union of ordinary alcohol or amylic alcohol ’with 
various acids,—that is to say, ethers which possess aro¬ 
matic odours more or less analogous to those of some 
fruits; but at present we are unable to say that these 
odours are due to the same principles. However this 
may be, the perfumers and the confectioners, more 
energetic and better advised than the chemists, imme¬ 
diately availed themselves of them. Artificial aromatic 
oils appeared for the first time at the exhibition in Lon¬ 
don, in 1851. There was to be seen a “ pear oil,” ex¬ 
haling an agreeable odour of Jargonelle pear, and use¬ 
ful in the aromatization of bonbons, which was only a 
solution of amyl-acetic ether in alcohol. By its'side was 
“apple oil,” having the perfume of the best pippins, 
obtained by dissolving amyl-valeric ether in alcohol. 
The most abundant essence was that of “ pine apple,” 
which was nothing but ordinary butyric ether. There 
was also “ essence of cognac,” or “grape oil,” employed 
for giving to brandy of inferior quality the choice aroma 
of cognac. But the product which w r as then, as now, 
the most important article of manufacture, was the 
“ essence of mirbane,” the odour of which corresponds 
entirely with that of essence of bitter almonds, and 
which in commerce is frequently substituted for the 
latter. The essence of mirbane is identical with nitro- 
benzol, produced by the reaction of nitric acid upon 
benzol. Benzol, in its turn, has a common origin with 
the aniline colours as one of the products of the dis¬ 
tillation of tar. 
Besides the essences above noticed, of which the 
manufacture is still growing in importance,. there are 
also prepared artificially essences of quince, strawberry, 
rum, etc. All these preparations, it may be mentioned, 
are used in the aromatization of various confectionery, 
liqueurs, and preserves, the products of industry replacing 
those of Nature. In every case the synthesis of the 
odoriferous principles ranks among the most beautiful 
triumphs of organic chemistry. 
Linnaeus, whose mind was eminently analytical and 
methodical, not only ranged animals and vegetables 
in orders, but also classified diseases, and even odours. 
He divided the latter into seven classes : aromatic 
odours, as those" of laurel leaves; fragrant odours, as 
those of the lily and jasmin; ambrosial odours, as those 
of ambergris and musk; alliaceous odours, as that of 
garlic; fetid odours, as those of the goat or the stink¬ 
ing goose-foot; repulsive odours, as those of many 
Solanacese ; and, finally, nauseous odours. The denomi¬ 
nations of Linnasus have generally prevailed in lan¬ 
guage, but they have only a conventional value. There 
is no standard for the comparison of odours ; they can 
only be arranged according to the degrees of analogy 
that exist between the impressions they make upon the 
olfactory nerve. They have no characters that can 
be rigorously defined, and therefore it is impossible to 
give them a natural classification. 
The sensations produced ,by odours are appreciated 
in very variable degrees, although with less di¬ 
versity than those of tastes. Montaigne says that he has 
seen those who feared the scent of apples more than 
arquebusades. History records that Louis XIV. could 
not endure perfumes. Gretry was distressed by the 
scent of roses, and the smell of a hare caused Mdlle. 
Contat to faint. Odours which to us are repugnant, as 
those of asafoetida and valerian root, are, on the con¬ 
trary, the delight of Orientals, who employ those sub¬ 
stances as condiments. M. Cloquet mentions a young 
gild who found great pleasure in the smell of old books, 
and a lawyer upon whom the exhalations of a dunghill 
produced the most agreeable sensations. Therefore, it 
is not possible to establish general rules concerning the 
influence of odours upon our organs, and the quality of 
sensations which they cause in us. Nevertheless, it is 
certain that in a physiological point of view there are 
some which exercise a constant action. Chardin, and 
other travellers, say that when the pouch containing the 
musk is removed from the animal, the operator is com¬ 
pelled to cover the mouth and nose with linen bandages, 
many folds thick, to avoid violent haemorrhage. 
Certain substances which, in a state of considerable 
diffusion, have an agreeable perfume, exhale, when in a 
concentrated state, a repugnant and, sometimes, dan¬ 
gerous odour. This is true, especially of patchouli, 
civet, and the essences of neroli and thyme. The 
odours of the lily, daffodil, violet, rose, elder, etc., when 
they attain a certain degree of concentration, exercise, 
ordinarily, an injurious effect upon the system, by caus¬ 
ing more or less violent headache, syncope, or even 
worse. The annals of science mention several cases of 
death due to the toxic action of certain odorous emana¬ 
tions. Labiate plants, as sage and rosemary, on the con¬ 
trary, appear to be endowed rather with salutary proper¬ 
ties. It is important, however, to distinguish between the, 
in some sort, purely dynamic action of the odour, intoxica¬ 
tion by the essence, and the effect of carbonic acid given 
off by the plants. These three causes have been con¬ 
founded by authors who have recorded cases of death 
occurring after more or less prolonged inhalation of fra¬ 
grant air. 
This variable action, sometimes salutary, sometimes 
hurtful, of odours upon the nervous system explains the 
part they have always played in the history of nations. 
