Origin. - A liquid containing about 80 per cent. of amyl (principally iso-amyl) nitrite. Obtained by the action of nitric acid upon amylic alcohol.

Description and Properties. - A clear yellow or pale-yellow liquid, of a peculiar, ethereal, fruity odor and a pungent, aromatic taste. Almost insoluble in water; miscible in all proportions with alcohol or ether. In alcoholic solution it gradually decomposes, with formation of ethyl nitrite and amylic alcohol. It should be kept in small, dark-colored, glass-stoppered bottles, in a cool and dark place, remote from lights and fire.

Dose. - 1/2-1 minim (0.03-0.06 Cc.) internally; for inhalation 1-5 minims (0.06-0.3 Cc.) [3 minims (0.2 Cc), U. S. P.].

Physiological Action. - Externally and Locally. - Its action is that of a mild irritant when applied to the skin.

Internally. - The following actions apply to ingestion or inhalation of the drug.

Circulatory System. - Almost immediately alter inhalation of amyl nitrite there is a marked flushing of the skin, first perceptible in the face, doubtless occasioned by dilatation of the capillaries. The heart's action is increased and somewhat weakened, and the pulse is soft and compressible. The blood-pressure falls very markedly, the condition being caused by a paralyzing action upon the muscle-fibers found in the walls of the small arterioles, causing marked dilatation. The same cause accounts for the change in the action of the heart, due to diminution of peripheral resistance. Amyl nitrite has little central action.

The inhalation of large amounts renders the heart very weak, toxic doses arresting that organ in diastole.

Nervous System. - Among the effects are cerebral oppression, flushing of the head and face, vertigo, headache, and confusion of ideas, with diminished reflex excitability, muscular weakness, and unsteadiness of gait, both the voluntary and involuntary muscles being relaxed. These actions are due to the depressing influence of the drug upon the motor areas of the brain and spinal cord.

Respiratory System. - Small doses quicken the respiration by lowering arterial pressure and possibly by moderate stimulation of the center, due to accumulation of carbon dioxide. Immoderate or toxic amounts render the breathing slow and labored from depression of the respiratory center and arrest of the oxygenating function of the blood.

Absorption and Elimination. - Amyl nitrite is rapidly absorbed, being eliminated chiefly by the kidneys, increasing the amount of urine, uric acid, and urea excreted. Sugar may frequently be detected in the urine, probably resulting from the action of the drug in dilating the hepatic vessels and increasing the circulation in the liver.

Blood. - Amyl nitrite, as all the nitrites, causes fixation meth-hemoglobin to take the place of oxyhemoglobin. Nitric-oxide-hemoglobin compounds are also formed. The blood becomes dark chocolate in color and asphyxiation may result, though rarely.

Temperature. - Bodily heat is reduced both in health and in fever, due to dilatation of the peripheral blood-vessels and a reduction of the oxygen-carrying power of the red blood-corpuscles.

Eye. - There is marked dilatation of the retinal vessels and hyperemia of the papilla, producing chromatopsia of the particolored variety and hallucinations of vision. These effects are usually transitory, and disappear with the elimination of the drug.

Uterus. - The uterine muscle is relaxed.

Untoward Action. - In addition to the symptoms described under "Poisoning," there have been noted gastric disturbance, nausea and vomiting, dryness of the mouth and trembling of the lips, irritation of the throat, defective vision, and subjective sensations of color, usually yellow vision.

Poisoning. - The toxic effects of amyl nitrite include an exceedingly rapid and weak heart, final retardation of the pulse, cyanosis of the face, slow and shallow respiration, cold extremities, subnormal temperature, great muscular weakness, abolished reflexes, vertigo, intense headache, and disordered vision. Death results from cardiac or respiratory failure. 3.0 Gm. swallowed by mistake by a sixty-year-old man has produced alarming symptoms lasting several hours. The characteristic banana-like odor is valuable in diagnosis. Fusel oil is not distinguishable from it by odor alone.

Treatment of Poisoning. - Strychnine and digitalis are required to sustain the heart; ergotin or atropine may be administered subcuta-neously, together with cold applications to the head, diffusible stimulants, and artificial respiration if necessary. Adrenalin is valuable.