“…The consequent enlarged set of Euler-Lagrange equations contain the transformed MaxwellLorentz equations, and enable certain properties of the energy-momentum tensor to be derived. These in turn lead to an identity, analogous to the elastostatic conservation law, whose construction, while nontrivial, appears to be more direct than is usual; compare for example, [Ericksen 2006, to appear;Maugin 1993;Maugin and Trimarco 1991;2001, Trimarco 20022003;and Pack and Herrmann 1986]. The Maxwell-Lorentz equations also imply that the electric enthalpy is independent of the polarization, so that the conditions for the electric enthalpy to be quasiconvex and rank-one convex, both essential for the proof, need only be defined in terms of the deformation gradient and the electric field.…”