On the Kinetic Theory of a Gas. Part II: A Composite Monatomic Gas: Diffusion, Viscosity, and Thermal Conduction

The present memoir was originally intended to deal only with the theory of diffusion, which still remains its chief subject. During the course of the work, however, it became clear that the theory of viscosity and thermal conduction could also be incorporated by a slight extension of the analysis. This has been done, and the paper now affords an account of all these three “ordinary” mean-free-path phenomena of a composite gas. The treatment of viscosity and conduction is brief, partly because the theory for a composite gas is so much more complex and less important than that for a simple gas. For the same reason the results are not carried to a higher degree of approximation than that attained, in regard to the same phenomena, in an earlier memoir. The present method, however, enables the approximation to be carried to any degree of accuracy, which was not formerly possible. Also a certain mistake in the previous investigation of the conductivity of a composite gas is indicated and corrected.