Abstract
Measurements have been made of the heat conductivity at 0, 50, and 150 C for three mixtures of nitrogen and carbon dioxide. At 50 C the conductivity of the pure compounds was measured over a range of pressure for constituents and mixtures. A discussion of the pressure effects is given, based upon a theoretical formula deduced by Enskog for pure gases, and it is found that to a good approximation the coefficients of p/T for the mixtures are a linear function of the composition. In the course of making the measurements on the mixtures a limit was observed of the pressures at which accurate results could be obtained. It is suggested in explanation of the phenomenon, that thermal diffusion causes a separation of the constituents in the temperature gradient of the apparatus. The conductivity cell employed was designed for measurements in the case of pure gases, to pressures far in excess of the pressures at which the effect was observed for the binary mixtures. The Enskog equation for the heat conductivity of binary mixtures at low pressure is applied to the heat-conductivity data for hydrogen-carbon dioxide at two temperatures and also to the new conductivity results for nitrogen-carbon dioxide mixtures. The comparison of observed and computed conductivities suggests the desirability of making new measurements on the hydrogen-carbon dioxide mixtures to determine whether or not the effect noted in making the new measurements has invalidated the older data.
