Viscosity measurements for the gaseous state of three binary mixtures of the methane-carbon dioxide system were carried out at 50, 100, 150 and 200 °C. for pressures ranging from 34 to 680 atm. The compositions of these mixtures were 0.243, 0.464 and 0.755 mole fraction methane. These measurements were made using an unsteady state capillary viscometer which had been used previously in the procurement of viscosities of pure substances.

The resulting measurements for these mixtures produced relationships between μ-μ* and ρ which were consistent in behavior with the corresponding relationships of the pure constituents of this binary system. When these variables were normalized with ϵ the viscosity parameter, and ρc, the critical density, the quantities (μ-μ*)ϵ and ρR for these mixtures and the pure components yielded a single relationship which can represent the viscosity behavior for this entire binary system.