in the growth of lavender and peppermint; the essential oils extracted
from these plants grown at Mitcham, in Surrey, realize eight times the
price in the market of those produced in France or elsewhere, and are
fully worth the difference for delicacy of odor.

The odors of plants reside in different parts of them, sometimes in the
roots, as in the iris and vitivert; the stem or wood, in cedar and
sandal; the leaves, in mint, patchouly, and thyme; the flower, in the
roses and violets; the seeds in the Tonquin bean and caraway; the bark,
in cinnamon, &c.

Some plants yield more than one odor, which are quite distinct and
characteristic. The orange tree, for instance, gives three--from the
leaves one called _petit grain_; from the flowers we procure _neroli_;
and from the rind of the fruit, essential oil of orange, _essence of
Portugal_. On this account, perhaps, this tree is the most valuable of
all to the operative perfumer.

The fragrance or odor of plants is owing, in nearly all cases, to a
perfectly volatile oil, either contained in small vessels, or sacs
within them, or generated from time to time, during their life, as when
in blossom. Some few exude, by incision, odoriferous gums, as benzoin,
olibanum, myrrh, &c.; others give, by the same act, what are called
balsams, which appear to be mixtures of an odorous oil and an inodorous
gum. Some of these balsams are procured in the country to which the
plant is indigenous by boiling it in water for a time, straining, and
then boiling again, or evaporating it down till it assumes the
consistency of treacle. In this latter way is balsam of Peru procured
from the _Myroxylon peruiferum_, and the balsam of Tolu from the
_Myroxylon toluiferum_. Though their odors are agreeable, they are not