Mint; hedyosmos, from its sweet smell; is a perennial herb with square stalks, serrated leaves set in pairs, and spikes of monopetalous flowers, each cut into four sections, and followed by four seeds inclosed in the cup. The species are numerous, but not hitherto described with sufficient accuracy. See Linnaean Transactions, vol. v. for an account of the British species by Dr. Smith.

Mentha aquatica, Lin. Sp. Pl. 805, sisymbrium sylvestre, mentha rotundifolia palustris. Red water mint. Its leaves are somewhat oily, and set on pedicles; the stamina long, standing out from the flowers.

Mentha cataria; nepeta cattaria, mentha felina, herba felis,calamintha palustris, nepetella,nepeta cataria Lin. Sp. Pl. 796, for cats are so delighted with the smell that they roll on it, and destroy the plant unless defended till it has acquired some strength. It is an hoary plant with square stalks; the leaves heart shaped, acuminated, serrated, and set in pairs on oblong pedicles; the flowers whitish, labiated, standing on spikes at the top of the branches. The upper lip is divided into two, and the lower into three, sections. It grows wild in hedges and on dry banks, and flowers in June; is moderately aromatic, of a strong smell, resembling a mixture of mint and pennyroyal, and participates of their virtues. Water dissolves their active matter; but rectified spirit extracts it more completely. Distilled with water, they yield a yellow essential oil, not quite so agreeable as the herb, though resembling it in smell: the remaining decoction is bitter and subastringent. See Raii Historia Plantarum; Cullen, Lewis, and Tournefort's Materia Medica.

Mentha corymbifera minor. See Ageratum.

Mentha crispa, Lin. Sp. Pl 805, agrees in its general virtues with the Mentha spicata, q. v.

Mentha hirsuta, var.δ . Smith, in the Linnaean Transactions, v. 196; probably a variety of the mentha sativa. See Flora Britannica.

Mentha palustris folio oblongo, mentastrum hirsutum, auricularia; hairy water mint, or earwort, has long hairy leaves, without pedicles, and broad spikes of flowers. All the water mints grow in marshes and on the banks of rivers, and flower towards the end of summer; their smell is less agreeable than that of spear mint, their taste more bitter and pungent: the second sort resembles the pennyroyal. They yield much less essential oil than the spear mint, and their virtues, though similar, are greatly inferior.

The hairy water mint is supposed to be auricularia, planta Zeylanica, or earwort, celebrated by Marloe for the cure of deafness.

Mentha piperitis. Pepper mint. Mentha pipe-rita Lin. Sp. Pl 805; hath acuminated leaves on very short pedicles, and the flowers set in short thick spikes or heads: it is a native of this kingdom, and its natural soil is a watery one; but in any other it does not degenerate.

Pepper mint hath a more penetrating smell, with a stronger and warmer taste than the other mints. In the mouth it feels at first hot, afterwards cold, and somewhat nitrous. From its stomachic, antispasmodic, and carminative qualities, it is of great use in flatulent complaints, hysteric depressions, nausea, and other dyspeptic symptoms; often producing immediate relief by diffusing a glowing warmth through the whole system. Its qualities are with great probability ascribed to the camphor, which the experiments of Gaubius have proved to be largely contained in it, and it is seldom injurious from its stimulus.

It readily and strongly impregnates either water or spirit by infusion: in distillation with water it gives over a large quantity of essential oil, of a pale greenish yellow colour, growing darker coloured by age, and possessing a great degree of the smell and pungency of the herb. As much of this oil as can be suspended in rectified spirit of wine is sold under the name of the essence of pepper mint. The decoction which remains after distillation, like that of the other mints, is bitterish and subastringent. For the water, spirit, and oil, see Mentha spicata.

Mentha pulegium. See Pulegium.

Mentha spicata; mentha sativa Lin. Sp. Pl 805, mentha vulgaris, hart mint, and common spear mint, hath oblong, narrow pointed leaves, joined close to the stalk, and small purplish flowers, standing on long spikes on the top. Though a native of warmer climes, it is common in our gardens, and flowers in June and July.

The smell of mint is agreeably aromatic, and the taste bitterish and moderately warm; it is carminative and stomachic, particularly useful in -relieving vomitings and weakness of the stomach. An infusion of mint in water is said to prevent the coagulation of milk in stomachs where acidity prevails; and in general this herb nearly resembles the pepper mint, though perhaps less efficacious as an antispasmodic, and more injurious as a stimulant. In vomitings from inflammation in the stomach it is injurious.

The juice expressed from the leaves retains the bitterness and astringency, but not the aroma of the mint, which, however, is not lost by keeping, drying, or a moderate degree of heat. In five or six hours cold water extracts the more agreeable and active parts of the mint; a longer maceration extracts the grosser and less agreeable portions. Hot water more quickly extracts its virtues, but boiling dissipates the aroma. Infusions and tinctures contain the whole virtue of the mint; the oil and the distilled water only the aroma.

Mint water should be distilled from the fresh herb, and it is improved by adding some dried mint. In distillation with water an essential oil rises, which is of a pale yellowish colour, changing by age to a reddish hue: about an ounce is procured from ten pounds of mint, which for this purpose should be gathered when the flower is expanding. The oil is not, however, an agreeable preparation.

Dry mint yields to spirit of wine, either with or without heat, all its virtue, without its disagreeable parts. Spirit takes up very little in distillation. An extract made with spirit possesses the concentrated virtues of a large portion of dried leaves. Fifteen grains of the resinous extract obtained from either the common mint or pepper mint, by means of spirit of wine, is said to be equivalent to six drachms of the dried herb. The spirituous tincture mixes with watery liquors without precipitation; but spirituous liquors impregnated with its pure volatile parts by distillation turn milky on the admixture of water. A conserve made in the usual way is an excellent vehicle for other medicines, in diseases of the stomach.

Tincture of mint is made by adding to a pint of mint water half an ounce of the dried leaves of mint: after standing four hours in a warm place, it must be strained. The distilled water contains as much of the volatile part of the herb as it can retain; but by infusion it takes up as much of the extractive matter as pure water. Thus any of the simple distilled waters may be much improved, and, when required, the waters distilled from one vegetable may be the menstruum for a different one.

The college of physicians order from the mentha sativa, and mentha piperitis, a water and a spirit, which are directed to be made as follows. Take of spear mint or pepper mint dried, one pound and a half, water sufficient to prevent an empyreuma; and to the same quantity of the herb they order one gallon of spirit, with water sufficient to prevent an empyreuma. In each process they draw off a gallon. The essential oils of each are obtained by distillation. See Oleum.