Amyl (Gr. starch), C5H11, the radical of amylic alcohol or potato spirit, a colorless liquid, with a somewhat aromatic odor, prepared by Frankland in 1849 by heating the iodide of amyl with an amalgam of zinc in sealed tubes for some hours at a temperature of from 320° to 356° F. It also occurs as an incidental product in the distillation of coal. As it doubles its molecular constitution whenever attempts are made to isolate it, the liquid described by Frankland is now commonly called diamyl, and the formula written (C5 H11)2. Amyl, or rather diamyl, has the specific gravity of 0.77 at 60° F., boils at 311° F.; becomes thick at 22° F., but does not freeze; takes fire when heated and burns with a smoky flame; mixes in all proportions with alcohol, but not with water; is not acted upon by fuming sulphuric acid, but slowly attacked by nitric and nitro-sulphuric acid, and decomposed after long digestion with pentachloride of phosphorus. Amyl by itself has no use in the arts, but is interesting to the scientific chemist on account of the great number of substitution products that have been derived from it. - Nitrate of amyl is an inflammable liquid, lighter than water, and having an odor like very ripe pears.

It produces in man, when inhaled in the dose of three or four drops, a sudden and violent acceleration of the pulse, with a peculiar flushing of the face. In animals it is capable of producing death. It may be regarded as a powerful general sedative, the peculiar action on man being due to a rapid relaxation of the muscular walls of the arterioles, giving rise to a suddenly diminished pressure of the blood in the arteries and heart. Its therapeutic applications are not yet extensive, but it has been used with good effect in angina pectoris, and some other diseases of a supposed spasmodic character.