This experiment was made in the morning; no languor or exhaustion was consequent, my feelings throughout the day were as usual, and I passed the night in undisturbed repose. [206] Dr. Beddoes has given some account of this experiment, in his Notice of some observations made at the Medical Pneumatic Institution. It was noticed in Mr. Nicholson’s Phil. Journal for May 1799. The next morning the recollections of the effects of the gas were very indistinct, and had not remarks written immediately after the experiment recalled them to my mind, I should have even doubted of their reality. I was willing indeed to attribute some of the strong emotion to the enthusiasm, which I supposed must have been necessarily connected with the perception of agreeable feelings, when I was prepared to experience painful sensations. Two experiments however, made in the course of this day, with sceptism, convinced me that the effects were solely owing to the specific operation of the gas. In each of them I breathed five quarts of nitrous oxide for rather a longer time than before. The sensations produced were similar, perhaps not quite so pleasurable; the muscular motions were much less violent. Having thus ascertained the powers of the gas, I made many experiments to ascertain the length of time for which it might be breathed with safety, its effects on the pulse, and its general effects on the health when often respired. I found that I could breathe nine quarts of nitrous oxide for three minutes, and twelve quarts for rather more than four. I could never breathe it in any quantity, so long as five minutes. Whenever its operation was carried to the highest extent, the pleasurable thrilling at its height about the middle of the experiment, gradually diminished, the sense of pressure on the muscles was lost; impressions ceased to be perceived; vivid ideas passed rapidly through the mind, and voluntary power was altogether destroyed, so that the mouth-piece generally dropt from my unclosed lips. Whenever the gas was in a high state of purity, it tasted distinctly sweet to the tongue and palate, and had an agreeable odor. I often thought that it produced a feeling somewhat analogous to taste, in its application to my lungs. In one or two experiments, I perceived a distinct sense of warmth in my chest. I never felt from it any thing like oppressive respiration: my inspirations became deep in proportion as I breathed it longer; but this phænomenon arose from increased energy of the muscles of respiration, and from a desire of increasing the pleasurable feelings. Generally when I breathed from six to seven quarts, muscular motions were produced to a certain extent; sometimes I manifested my pleasure by stamping or laughing only; at other times, by dancing round the room and vociferating.