On transformations of internal vectorial variables in the thermodynamic theory of dielectric relaxation and the invariance of Onsager's reciprocal relations

In some previous papers one of us developed a theory of dielectric and magnetic relaxation phenomena based on non-equilibrium thermodynamics. In one of these papers possible cross effects between dielectric (or magnetic) relaxation and heat conduction were discussed. It was shown in particular that Onsager's relations for these cross effects are invariant under a transformation of the vectorial internal variable. (This variable was introduced in the description of dielectric relaxation). In the present paper we shall extend the discussion to a broader class of irreversible phenomena. (Two types of dielectric or magnetic relaxation, which give rise to two relaxation times, heat conduction, electrical conduction and viscous flow.)