A Point Affecting the Diffusion of the Gases of the Atmosphere in Relation to Health

Article metrics


THE great importance in relation to health of the part played by the internal motion of gases, as indicated by the now established and admirably simple kinetic theory, would seem scarcely to receive adequate appreciation. The old and vaguely developed statical idea of a stagnant atmosphere with molecules at rest, has given place to the opposite view of a high activity of motion, even when the atmosphere appears to the senses to be still. By this motion noxious vapours or gases, instead of remaining stagnant, are rapidly scattered by diffusion, and thereby rendered harmless. The part apparently played here by inequality of molecular velocity (dependent on inequality of molecular mass) in contributing to this end, would seem scarcely to have received the attention it appears to deserve. In Prof. Tait's work, “Lectures on some Recent Advances in Physical Science” (p. 237, second edition), reference is made to the diffusion of the gases of the atmosphere under the kinetic theory, and here it would seem as if the influence of the inequality of the normal velocity of the molecules of the different gases of the atmosphere (dependent on inequality of molecular mass) had not been taken into account, and hence it would appear as if the gases in their mutual diffusion were regarded as subject to the pure contingencies of chance, as they would be if the velocities of the molecules were equal (or their masses equal); this necessarily leading to some rather startling conclusions, which make the continuance of life and health (as dependent on the equable mixture of the constituents of the atmosphere) a matter more or less dependent on contingency or accident. The passage in question runs as follows:—

Rights and permissions

Reprints and Permissions

About this article

Cite this article

PRESTON, S. A Point Affecting the Diffusion of the Gases of the Atmosphere in Relation to Health . Nature 20, 366–368 (1879) doi:10.1038/020366a0

Download citation


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.