I soon learnt from Mr. D. himself the course of his experiments; many of which were in the highest degree hazardous, when, with friendly earnestness, I warned him against his imminent perils. He seemed to act, as if in case of sacrificing one life, he had two or three others in reserve on which he could fall back in case of necessity. He occasionally so excited my fears that I half despaired of seeing him alive the next morning. He has been known sometimes to breathe a deadly gas, with his finger on his pulse, to determine how much could be borne, before a serious declension occurred in the vital action. The great hazards to which he exposed himself may be estimated by the following slight detail.
Dr. Mitchell, as well as Dr. Priestley, had stated the fatal effects on animal life, of the gazeous oxide of azote; Mr. Davy, on the contrary, for reasons which satisfied himself, thought it respirable in its pure state; at least, that a single inspiration of this gas might neither destroy, nor materially injure the powers of life. He tried one inspiration. No particularly injurious effects followed. He now breathed, out of his green bag, three quarts of this nitrous oxide (gazeous oxide of azote,) when it was attended with a degree of giddiness, great fulness in the head, and with loss of distinct sensation and voluntary power, analogous to intoxication. Not being able fully to determine whether the gas was "stimulant" or "depressing," he now breathed four quarts of it from his green bag, when an irresistible propensity to action followed, with motions, various and violent. Still, not being satisfied, he proceeded in his experiments, and at length found that he could breathe nine quarts for three minutes, and twelve quarts for rather more than four, but never for five minutes, without the danger of fatal consequences, as before five minutes had expired, the mouth-piece generally dropped from his unclosed lips. By breathing from six to seven quarts only, muscular motions were produced, and he manifested the pleasure it excited, by stamping, laughing, dancing, shouting, &c.
At another time, having ascertained that his pure nitrous oxide, was eminently stimulant, he wanted to determine whether the system, in a high state of stimulation, would then be susceptible of a proportionate accession of stimulus from his new gas; like that which would be experienced by the man, who after taking one bottle of wine, drank a second; and to acquire demonstration on this nice subject, (although he was a confirmed water-drinker) to form the basis of his experiment, he drank off with all despatch a whole bottle of wine, the consequence of which was, that he first reeled, and then fell down insensibly drunk. After lying in this state for two or three hours, he awoke with a sense of nausea, head-ache, and the usual effects of intoxication. At the first return of recollection, however, undaunted by the past, the young enthusiastic philosopher called out for the green bag, when he breathed twelve quarts of nitrous oxide, for three or four minutes. The consequence of this was, he became a second time intoxicated, though in a less degree, when he strode across the room, and by stamping, laughing, dancing, and vociferation, found that the same effects followed, which attended his former experiment, without any increase of stimulus from the wine.
All the gases that had hitherto been the subject of investigation, sunk in importance before this nitrous oxide, which the perseverance of Mr. Davy had now obtained in its pure state, in any quantity and consequently divested of that foreign admixture which rendered it usually so destructive. He had also ascertained the quantity which might safely be admitted into the lungs. Dr. Beddoes was sanguine as to its medical qualities, and conceived that, if not a specific, it might prove highly advantageous in paralysis, and pulmonary affections; and, in conjunction with these benefits he well knew it would confer importance on his own Pneumatic Institution. As Dr. B. meditated a publication expressly on this subject, he was desirous of collecting the testimony of others, for which purpose, he persuaded several of his friends to breathe this innocent, but exhilarating nitrous oxide, while they described, and he recorded their sensations.
Mr. Southey, Mr. Clayfield, Mr. Tobin, and others inhaled the new air. One, it made dance, another laugh, while a third, in his state of excitement, being pugnaciously inclined, very uncourteously, struck Mr. Davy rather violently with his fist. It became now an object with Dr. B. to witness the effect this potent gas might produce on one of the softer sex, and he prevailed on a courageous young lady, (Miss ——) to breathe out of his pretty green bag, this delightful nitrous oxide. After a few inspirations, to the astonishment of every body, the young lady dashed out of the room and house, when, racing down Hope-square, she leaped over a great dog in her way, but being hotly pursued by the fleetest of her friends, the fair fugitive, or rather the temporary maniac, was at length overtaken and secured, without further damage.
Dr. Beddoes now expressed a wish to record my testimony also, and presented me his green bag; but being satisfied with the effects produced on others, I begged to decline the honour. The Pneumatic Institution, at this time, from the laughable and diversified effects produced by this new gas on different individuals, quite exorcised philosophical gravity, and converted the laboratory into the region of hilarity and relaxation. The young lady's feats, in particular, produced great merriment, and so intimidated the ladies, that not one, after this time, could be prevailed upon to look at the green bag, or hear of nitrous oxide, without horror!
But more perilous experiments must now be noticed. Mr. Davy having succeeded so well with the Nitrous Oxide, determined even to hazard a trial with the deadly Nitrous Gas. For this purpose he placed in a bag, "one hundred and fourteen cubic inches of nitrous gas," and knowing that unless he exhausted his lungs of the atmospheric air, its oxygen would unite with the nitrous gas, and produce in his lungs aqua-fortis, he wisely resolved to expel if possible, the whole of the atmospheric air from his lungs, by some contrivance of his own. For this purpose, in a second bag, he placed seven quarts of nitrous oxide, and made from it three inspirations, and three expirations, and then instantly transferred his mouth to the nitrous gas bag, and turning the stop-cock, took one inspiration. This gas, in passing through his mouth and fauces, burnt his throat, and produced such a spasm in the epiglottis, as to cause him instantly to desist, when, in breathing the common air, aqua-fortis was really formed in his mouth, which burnt his tongue, palate, and injured his teeth. Mr. D. says, "I never design again to repeat so rash an experiment."
But though this experiment might not be repeated, there was one other nearly as dangerous, to which Mr. Davy's love of science prompted him to resort; not by trying it on another but, generously, on himself.
Mr. Davy wished to determine whether the carburetted hydrogen gas, was so destructive to animal life as had been represented. In its pure state, one inspiration of this gas was understood to destroy life, but Mr. D. mixed three quarts of the gas, with two quarts of the atmospheric air, and then breathed the whole for nearly a minute. This produced only slight effects, (nothing to an experimental chemist;) merely "giddiness, pain in the head, loss of voluntary power," &c.
The spirit of inquiry not being to be repressed by these trifling inconveniences, Mr. Davy was now emboldened to introduce into his green bag, four quarts of carburetted hydrogen gas, nearly pure. After exhausting his lungs in the usual way, he made two inspirations of this gas. The first inspiration produced numbness and loss of feeling in the chest. After the second, he lost all power of perceiving external things, except a terrible oppression on his chest, and he seemed sinking fast to death! He had just consciousness enough to remove the mouth-piece from his unclosed lips, when he became wholly insensible. After breathing the common air for some time, consciousness was restored, and Mr. Davy faintly uttered, as a consolation to his then attendant, Mr. John Tobin, "I do not think I shall die."