159. Mentha Piperita, Linn.—Peppermint.
Sex. Syst. Didynamia, Gymnospermia.
(Herba florens et exsiccata. Oleum ex herba florente destillatum, L.—Herb; Volatile oil, E.—The herb, D.)
History.—The ancient Greeks [Hippocrates, De victûs rat. lib. ii. p. 359, ed. Foes.; Dioscorides, lib. iii. cap. 36.] employed in medicine a plant which they called Μίνθος, or Μίνθη, and which, on account of its very agreeable odour, was also termed Ηδύοσμον, or the sweet-smelling herb. It was probably a species of Mentha; and, according to Fraas, [Synop. Plant. Fl. Classicae, 1845.] was the M. piperita, Linn.; the Ηδύοσμον πεπερώδες of the modern Greek Pharmacopoeia.
Peppermint came into use in England in the last century; at least Hill, [Hist. of the Mat. Med. p. 358.] in 1751, says that it "has lately got into great esteem;" and Geiger [Handb. d. Pharm. Bd. iii. S. 1230.] says it was introduced into Germany as a medicine, through the recommendations of the English, in the latter half of the last century.
Botany. Gen. Char.—See Mentha viridis.
Sp. Char.—Stem smooth. Leaves petiolated, ovate-oblong, acute, serrate, rounded-crenate at the base, smooth. Spikes lax, obtuse, short, interrupted at the base. Pedicels and calyxes at the base smooth; teeth hispid (Bentham).—Creeping-rooted.
Var. β. sub-hirsuta, Bentham; M. hirsuta δ, Smith. The nerves of the under surface of the leaves, as well as the petioles, hairy.
Hab.—Watery places. Indigenous. Extensively cultivated at Mitcham, in Surrey, from whence the London market is principally supplied. Found in various parts of Europe; also in Asia, Africa, and America.
Properties.—The whole herb (herba menthae piperitae) is officinal. It has a peculiar aromatic odour, and a warm, burning, bitter taste, followed by a sensation of coolness when air is drawn into the mouth. Sesquichloride of iron communicates a green colour (tannate of iron) to the cold infusion of peppermint.
Composition.—The principal constituents are volatile oil, resin? a bitter principle, tannic acid, and woody fibre.
Physiological Effects.—Peppermint is an aromatic or carminative, stimulant, and stomachic. It is the most agreeable and powerful of all the mints.
Uses.—It is employed in medicine for several purposes, but principally to expel flatus, to cover the unpleasant taste of other medicines, to relieve nausea, griping pain, and the flatulent colic of children. The following are the officinal preparations with their uses:—
1. OLEUM MENTHAE PIPERITAE, L. E. D.; Oil of Peppermint—(Obtained by submitting the fresh herb to distillation with water.)—It is colourless, or nearly so, sometimes having a pale yellow or greenish tint, and becoming reddish by age. It has a penetrating odour like that of the plant, and a burning aromatic taste, followed by a sensation of cold. The vapour of it applied to the eye causes a feeling of coldness.
Oil of peppermint consists of two isomeric oils—one liquid, the other solid; the latter is called peppermint-camphor, or the stearoptene of oil of peppermint. Its composition is C20H20O2. It is in colourless prisms, which have the odour and taste of peppermint, are almost insoluble in water, but readily soluble in alcohol and ether, and are fusible at 92° F. Under the influence of phosphoric acid, peppermint-camphor loses 2HO, and becomes a colourless liquid oil, called menthene C20H18.
I have met with three varieties of oil of peppermint:—
α. English Oil of Peppermint.—This is the finest sort. Its sp. gr. is 0.902. It is obtained at Mitcham. In a warm, dry, and favourable season, the produce of oil, from a given quantity of the fresh herb, is double that which it yields in a wet and cold season. The largest produce is three drachms and a half of oil from two pounds of fresh peppermint, and the smaller about a drachm and a half from the same quantity. [Brande, Dict. of Mat. Med. p. 356.] I was informed by a distiller at Mitcham, that twenty mats of the herb (each mat containing about 1 cwt.) yields about seven lbs of oil.
β. American Oil of Peppermint.—In odour and flavour it is inferior to the preceding sort. It is said to be prepared from the dried plant gathered when in flower (Brande). It yields a considerable quantity of camphor.
γ. China Oil of Peppermint.—Po ho-yo.—For a sample of this I am indebted to Dr. Christison. It comes from Canton. It consists chiefly of peppermint-camphor, and forms a white crystalline solid even in summer.
Oil of peppermint is said to be adulterated with oil of rosemary; [Pharmaceutical Journal, vol. i. p. 263, 1841.] the odour would probably serve to distinguish the fraud.
Oil of peppermint is carminative and stimulant, and is used occasionally as an antispasmodic. It is taken on sugar, in doses of from gtt. ii to gtt. v.
2. SPIRITUS MENTHAE PIPERITAE, L.; Spiritus Menthae, E.; Spirit of Peppermint.—(Prepared with the Oil of Peppermint, in the same way as the Spiritae Menthae viridis, L., before described. The Edinburgh College prepares it thus: Peppermint, fresh, ℔iss; Proof Spirit Ovij. Macerate for two days in a covered vessel; add a pint and a half of water, and distil off seven pints.)—A solution of the oil of peppermint may with great propriety be substituted for the preparation of the Pharmacopoeias. The spirit of peppermint is given in doses of from fʒss to fʒij.
3. ESSENTIA MENTHAE PIPERITAE, D.; Essence of Peppermint—(Oil of Peppermint f℥i; Stronger Spirit f℥ix. Mix with agitation.)—[This is the Tr. Olei Menthae Piperitae, U. S. The Formula as for Tincture of Oil of Spearmint] Some persons add peppermint or spinach leaves to communicate a green colour. The dose of this essence is from gtt. xx to gtt. xxx, on sugar.
4. AQUA MENTHAE PIPERITAE, L. E. D.—(Prepared with the herb or the oil of peppermint, in the same way as the Aqua Menthae viridis.)—Carminative and stimulant. Used to relieve flatulency, and as a vehicle for other medicines. Dose, f℥j to f℥iij.
Besides the above, there are several popular preparations of peppermint extensively used.
α. Infusum Menthae piperitae (Peppermint Tea) is prepared in the same way as spearmint tea.
β. Elaeosaccharum Menthae piperitae, Ph. Bor., is prepared by mixing ℥j of the whitest sugar, in powder, with gtt. xxiv of the oil of peppermint.
γ. Rotulae Menthae piperitae (in planoconvex masses, called peppermint drops—in flattened circular disks, termed peppermint lozenges) should consist of sugar and oil of peppermint only, though flour is sometimes introduced.
The liqueur sold at the spirit-shops as mint or peppermint is used as a cordial.