Viscosities of polar gases by relaxation of capillary flow

A simple method is described in which capillary flow is measured by the exponential decay of capacitance difference of gases in two reservoirs connected to the ends of the capillary and viscosity is determined from the time constant. Results for Ar, CH3F, CHF3, and CH3CF3 in the temperature range 20–150°C are given, together with 12–6 potential parameters derived using the theory of Monchick and Mason. These parameters for the polar gases are believed to give a much better description of the central forces than parameters derived from pressure virial coefficients.