Origin. - A volatile oil distilled from the fresh or partly dried leaves and flowering tops of peppermint, yielding not less than 8 per cent. of ester, calculated as menthyl acetate, and not less than 50 per cent. of total menthol.

Description and Properties. - A colorless liquid, becoming darker and thicker by age and exposure to the air, having the characteristic strong odor of peppermint and a strongly aromatic, pungent taste, followed by a sensation of cold upon inhalation. It forms a clear solution with an equal volume of alcohol, becoming turbid when further diluted, and is soluble in all proportions in carbon disulphide and in glacial acetic acid.

When exposed to a freezing temperature the oil becomes thick and cloudy, and separates crystals of menthol, to which it owes its peculiar odor.

Dose. - 1-5 minims (0.06-0.3 Cc) [3 minims (0.2 Cc), U. S. P.].

Official Preparations

Aqua Mfenthae Piperitae (0.2 per cent.) - Aquae Menthae Piperitae - Peppermint Water. - Dose, 1/2-1 fluidounce (15.0-30.0 Cc.) [4 drams (16 Cc.), U. S. P.].

Spfritus Menthae Piperitae (10 per cent.)Spiritus Meinthae Piperitae - Spirit, or Essence, of Peppermint. - Dose, 5-60 minims (0.3-0.4 Cc.) [30 minims (2 Cc), U. S. P.].

Spirit of peppermint is an ingredient of mistura rhei et sodse.