This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Citrea Malus. Malus medica C. B. Citrus medica Linn. Citron: a small evergreen tree, resembling the lemon, and differing from it chiefly in the fruit; which is much larger, less juicy, and contains, under the yellow rind, a thicker fungous white bark. It is a native of Asia, and cultivated in the southern parts of Europe.
This fruit has a near affinity with lemons in its medicinal qualities as well as in its external form: the principal difference lies, in the juice of the citron being somewhat less acid, and the yellow rind being somewhat hotter and accompanied with a considerable bitterishness. The rind gives out its virtue, equally with that of lemons, both to watery and spirituous menstrua; but its flavour is not equally retained in the spirituous extract, the essential oil of citron peel being very light and volatile, so as in great part to rife in distillation along with the highest rectified spirit. Several varieties of these trees are common in the warmer climates. Oils obtained from the fresh peels of the more odoriferous kinds, by rolling the fruit on a plane stuck full of points, are brought from Italy, and used as perfumes: these are somewhat more grateful, and considerably less pungent, than such as are drawn by distillation with water. The oil prepared in either of these ways is very subject to lose of its fine flavour, and become thick and resinous in keeping: when distilled with rectified spirit, and afterwards separated from the spirit by dilution with a large portion of water, it retains much longer its odour, fluidity, and limpidness.
Essentia dc cedro German.
Ol. cedrin Ph. Paris.