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." Such are some of the appalling hazards encountered by M. Davy, in his intrepid investigation of the gases. These destructive experiments, during his residence at Bristol, probably, produced those affections of the chest, to which he was subject through life, and which, beyond all question, shortened his days. Nothing at this moment so excites my surprise, as that Mr. D.'s life should have been protracted, with all his unparalleled indifference concerning it, to the vast age, for him, of fifty years.