On the 8th, I inspired five quarts without any mixture of common air, but the effects were not equal to those produced the day before; Indeed there were reasons for supposing that the gas was impure.
On the 18th, I breathed nearly six quarts of the pure nitrous oxide. It is not easy to describe my sensations; they were superior to any thing I ever before experienced. My step was firm, and all my muscular powers increased. My senses were more alive to every surrounding impression; I threw myself into several theatrical attitudes, and traversed the laboratory with a quick step; my mind was elevated to a most sublime height. It is giving but a faint idea of the feelings to say, that they resembled those produced by a representation of an heroic scene on the stage, or by reading a sublime passage in poetry when circumstances contribute to awaken the finest sympathies of the soul. In a few minutes the usual state of mind returned. I continued in good spirits for the rest of the day, and slept soundly.
Since the 18th of May, I have very often breathed nitrous oxide. In the first experiments when pure, its effects were generally similar to those just described.
Lately I have seldom experienced vivid sensations. The pleasure produced by it is slight and tranquil, I rarely feel sublime emotions or increased muscular power.
J. W. Tobin.
October, 1799.
II. Detail of Mr. Wm. Clayfield.
The first time that I breathed the nitrous oxide, it produced feelings analogous to those of intoxication. I was for some time unconscious of existence, but at no period of the experiment experienced agreeable sensations, a momentary nausea followed it; but unconnected with languor or head-ache.
After this I several times respired the gas, but on account of the fulness in the head and apparent throbbing of the arteries in the brain,[222] always desisted to breathe before the full effects were produced. In two experiments however, when by powerful voluntary efforts I succeeded in breathing a large quantity of gas for some minutes, I had highly pleasurable thrillings in the extremities, and such increase of muscular power, as to be obliged to exert my limbs with violence. After these experiments, no languor or depression followed.
William Clayfield.