In his 1931 papers, Onsager mentioned that his diffusion driving forces and fluxes, when multiplied and added pairwise, summed to the entropy generation. In 1945 he stated a minimum-dissipation principle, that any set of forces and fluxes which yield the entropy generation when so added would also yield a symmetric transport matrix. This last statement has been criticized by Coleman and Truesdell. This work discusses how to construct a transport formulation with a symmetric matrix and how to connect Onsager's forces and fluxes with gradients of mole fractions and species velocity differences. More general sets of forces and fluxes can be expressed in terms of those given here. (C) 2009 Published by Elsevier Ltd.