Peppermint is the herb of Mentha piperita, a small, herbaceous perennial, indigenous in Europe, but naturalized in this country, and cultivated largely in England and the United States. The herb should be gathered at the flowering period in August.

Sensible Properties. Peppermint has a quadrangular stem, branching near the top, from one to two feet long, with leaves opposite, petiolate, ovate, serrate, pointed, dark-green on the upper surface, and paler on the under. The flowers are small, purple, and arranged in terminal spikes, which are rounded at top, and interrupted beneath. All parts of the plants are aromatic, either fresh or dried; but the herb rapidly deteriorates by keeping, and at length becomes inert. It has a penetrating, grateful, somewhat camphorous odour, and a pungent, glowing, camphorous, bitterish taste, which is followed by a sense of coolness when the air is drawn through the mouth.

Active Principles

The virtues of the herb may be said to depend exclusively on its volatile oil; for, though there is a trace of tannic acid, and probably a small proportion of some bitter principle, these are insufficient materially to modify its effects. The volatile oil is obtained by distillation with water. It is at first nearly colourless, but gradually becomes greenish-yellow, and ultimately reddish-brown. Its odour and taste are like those of the herb. It is lighter than water. It is often adulterated, especially with alcohol, which, if in considerable quantity, may be readily detected by agitation with water, which abstracts the alcohol from the oil, and thus diminishes its bulk.

Medical Properties and Uses

Peppermint has all the characteristic properties of the aromatics, and may be used for all their general purposes (see page 315). The fresh herb is sometimes applied externally," well bruised, over the stomach and bowels, in infantile vomiting and colic. It is a good remedy, thus employed, in the earlier stages of cholera infantum. Internally the medicine may be given, in the form of infusion, in colicky pains and flatulence; but the preparation almost universally employed in this way is the volatile oil.

The Infusion, made in the proportion of half an ounce to a pint, may be given in doses of a wineglassful.

The Oil (Oleum Menthae Piperitae, U. S., Br.) is very much used in this country, being almost universally preferred to the herb for obtaining the effects of the medicine by internal exhibition. It is recognized in the British Pharmacopoeia, and directed to be prepared by distillation of the herb; though the herb itself is not among its officinals. The dose of it is from one to three drops, which may be prepared for administration by first rubbing it with a little loaf sugar, and then mixing with water. In consequence, however, of its extreme pungency, the oil is usually given dissolved in water or alcohol, in one of the following preparations.

Spirit of Peppermint (Spiritus Menthae Piperitae, U. S., Br.; Tinctura Olei Menthae Piperitae, U. S. 1850) or essence of peppermint, as the preparation is generally called, is made by dissolving a fluidounce of the oil in fifteen fluidounces of stronger alcohol, and afterwards macerating with the solution, for twenty-four hours, two drachms of the powdered leaves, which are separated by filtration. In the British process the oil is simply dissolved in the alcohol. The spirit is of such a strength as to admit of being taken into the mouth, simply dropped on a piece of sugar. It is a very popular preparation, and often used for the relief of nausea, gastric pains, colic, and flatulence. The dose is from ten to twenty drops. It may be given as above stated, simply dropped on a piece of sugar, or diffused by means of sugar in water.

Peppermint Water (Aqua Menthae Piperitae, U. S.), formerly pre-pared exclusively by distilling water from the fresh herb, is now made by simply dissolving the oil in water, through the intervention of carbonate of magnesia. The present U. S. Pharmacopoeia, however, admits distillation from the herb as an alternative process. Peppermint water is probably more used in this country as a vehicle for substances given in the form of mixture, than any other aromatic preparation. It serves to render the mixture more acceptable both to the palate and stomach, and to obviate griping. Each fluidounce of it contains about a minim of the oil. It may be given internally, for the ordinary purposes of the medicine, in the dose of from one to three fluidounces.

Peppermint Lozenges (Trochisci Menthae Piperitae, U. S.), consisting of the oil, sugar, and mucilage of tragacanth, afford a convenient form of the medicine for slight cases; as they may be carried in the pocket, and one of them taken as required. They are to be allowed slowly to dissolve in the mouth. They are, however, very feeble; ten of them being scarcely equivalent to a minim of the oil.