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EXTRAITS or ESPRITS; a few exceptions prove this rule.
Essential oil of orange-peel, and of lemon-peel, are frequently termed
in the trade "Essence" of orange and "Essence" of lemons, instead of
essential oil or otto of lemons, &c. The sooner the correct nomenclature
is used in perfumery, as well as in the allied arts, the better, and the
fewer blunders will be made in the dispensatory. It appears to the
writer, that if the nomenclature of these substances were revised, it
would be serviceable; and he would suggest that, as a significant,
brief, and comprehensive term, Otto be used as a prefix to denote that
such and such a body is the odoriferous principle of the plant. We
should then have otto of lavender instead of essential oil of lavender,
&c. &c. In this work it will be seen that the writer has generally used
the word OTTO in place of "essential oil," in accordance with
his views. Where there exists a solution of an essential oil in a fat
oil, the necessity of some such significant distinction is rendered
obvious, for commercially such articles are still called "oils"--oil of
jasmine, oil of roses, &c. It cannot be expected that the public will
use the words "fat" oil and "essential" oil, to distinguish these
differences of composition.

There are several good reasons why the odoriferous principle of plants
should not be denominated oils. In the first place, it is a bad
principle to give any class of substances the same signification as
those belonging to another. Surely, there are enough distinguishing
qualities in their composition, their physical character, and chemical
reaction, to warrant the application of a significant name to that large
class of substances known as the aroma of plants!

When the chemical nomenclature was last revised, the organic bodies
were little dealt with. We know that we owe this universal "oil" to the
old alchemist, much in the same way as "spirit" has been used, but a
little consideration quickly indicates the folly of its continued use.
We can no longer call otto of rosemary, or otto of nutmegs, essential
oil of rosemary or nutmegs, with any more propriety than we can term
sulphuric acid "oil" of vitriol. All the chemical works speak of the
odoriferous bodies as "essential" or "volatile" oils, and of the greasy
bodies as "fat" or "unctuous" oils. Oils, properly so called, unite with
salifiable bases and form soap; whereas the essential or volatile oils,
_i.e._ what we would pl