Comment on "Structure of ferrofluid dynamics"

We compare known equations for ferrofluid magnetization with a recently proposed rectified Debye theory [H. W. Müller and M. Liu, Phys. Rev. E 64, 061405 (2001)] and demonstrate that the latter is unsatisfactory. Derived by a purely formal method, it contains numerous unknown parameters, fails to explain previous experiments, and has no heuristic force.