The physical properties of fluids are perhaps among the most extensively investigated physical constants of any single group of materials. This is particularly true of the thermodynamic prop- erties of pure substances since the condition of thermodynamic equilibrium provides the simplest considerations for experimental measurement as well as theoretical treatment. In the case of non- equilibrium transport properties, the situation is significantly complicated by the necessity of measurement of gradients in the experiment and the mathematical difficulties in handling non- equilibrium...