"Stephen Hales... had distilled many substances of vegetable, animal, and mineral origin ; among them he treated many which must have produced impure hydrogen, marsh-gas, carbonic-acid gas, and oxygen; but Hales contented himself with measuring the volume of gases obtained from a known weight of material, without concerning himself as to their properties. And, as the result of many experiments, he concluded that "our atmosphere is a chaos, consisting not only of elastick, but also of unelastick air-particles, which in plenty float in it, as well as the sulphureous, saline, watry, and earthy particles, which are no ways capable of being thrown off into a permanently elastick state, like those particles which constitute true permanent air." This was the current belief as regards the nature of air."