Viscosity of dilute gases and vapors.

The well-known formula for calculating the viscosity of hard sphere gases, eta(o) = 2(mkT)(1/2)/3pi(3/2)sigma(2), where sigma(2) is molecular cross section, is altered to eta(o) = K(MT)(1/2)/V(t) (2/3), where V(t) is the molal volume of a liquid that has expanded sufficiently to permit mean free paths long enough to have significant fractions of the random thermal momenta of molecules in free flight and M is molal mass.This formulation places upon a single straight line points for all nonpolar molecules, mono- and polyatomic molecules alike, over long ranges of temperature.