Nitrite of amyl is a highly-vaporizable fluid, which possesses the following remarkable physiological action: the inhalation even of a very small quantity is followed, after a minute or so, by a sudden acceleration of the heart's action, accompanied by intense crimson congestion of the vessels of the face and conjunctiva, and a sense of enormous fulness in the head; these phenomena are extremely fugitive, passing away completely in two or three minutes, unless the inhalation is renewed. These characteristic effects had for some years been experimentally exhibited by Dr. Fraser and others, but the practical application of amyl to the treatment of angina was first suggested, I believe, by Dr. Brunton, in the case of a patient under the treatment of Dr. Maclagon and Dr. Bennett, in the Edinburgh Royal Infirmary. The angina was in this case symptomatic, there being advanced valvular disease of the heart. Comparative examinations with the sphygmograph, during the intervals and during the paroxysms, made strikingly manifest the fact that, during the attacks, there was an increase of arterial tension which was directly proportionate to the severity of the pain and cardiac embarrassment. It was thus suggested to Dr. Brunton's mind that nitrite of amyl, by relaxing the systemic arteries, might remove the unnatural tension, and give relief to the pain; and the result confirmed this hope. Doses of five and ten drops were inhaled from a towel, with the uniform result of at once quieting the pain; it might return in a few minutes, but a second dose usually removed it entirely for many hours. Various other cases have since been reported, in which similar relief was obtained, and I had occasion to employ it myself in one instance. The gentleman whose case has been related above (see page 101), as an example of the relief obtainable by the use of ether began to suffer rather more severely from his attacks than had been the case for some time, toward the end of the year 1869. I now determined to try the amyl, and accordingly left a small bottle containing half an ounce of it in his possession, with exact instructions to the following effect: On the first symptoms of a paroxysm of angina, he was to get the bottle open, and as soon as their character was fully declared he was to put the bottle to one nostril (closing the other with the finger, and keeping the mouth shut) and take one long, powerful inspiration. The result of his first experiment was very remarkable: the first sniff produced, after an interval of a few seconds, the characteristic flushing of the face and sense of fulness of the head; the heart gave one strong beat, and then at once he passed from the state of agony to one of perfect repose and peace, and at his usual bedtime slept naturally. This experience was repeated on several occasions, and for a considerable time the patient retained such full confidence in the remedy that he discarded all use of ether, and greatly reduced his