Low-Temperature Viscosities and Intermolecular Forces of Simple Gases

The viscosities of nitrogen, helium, neon, and methane have been measured in the temperature range 77–374°K relative to that of nitrogen at 273°K. The nitrogen viscosities are within 0.5% of those obtained in an earlier investigation except at one temperature, 114°K, where a difference of 1.5% is noted. The results for methane are close to those of earlier workers except at the lowest temperatures, but the results for helium and neon are from 1% to 2.5% above previous data below room temperature. The relationship between the low‐temperature transport properties of gases and dispersion forces is examined in detail and a comparison is made of the coefficients of $r^{\text{−6}}$ determined experimentally and theoretically. The phenomenon of a maximum or minimum in the ratio of viscosities for two gases is noted, and a test of intermolecular potential functions based on this fact is suggested. The agreement between several potential functions and the recent results of the authors for the viscosity of argon is examined.