where formula_80 is the viscosity at temperature formula_81. if formula_10 is known from experiments at formula_83 and at least one other temperature, then formula_78 can be calculated. it turns out that expressions for formula_10 obtained in this way are accurate for a number of gases over a sizable range of temperatures. on the other hand, argue that this success does not imply that molecules actually interact according to the sutherland model. rather, they interpret the prediction for formula_10 as a simple interpolation which is valid for some gases over fixed ranges of temperature, but otherwise does not provide a picture of intermolecular interactions which is fundamentally correct and general. slightly more sophisticated models, such as the lennard-jones potential, may provide a better picture, but only at the cost of a more opaque dependence on temperature. in some systems the assumption of spherical symmetry must be abandoned as well, as is the case for vapors with highly polar molecules like ho.