We discuss a modification of Weber's law proposed by T. E. Phipps. We calculate the energy and force on a charge moving inside and outside a capacitor according to Phipps's modification of Weber's electrodynamics. When Phipps postulated his potential energy he answered Helmholtz's criticism of Weber's law (the negative mass behaviour). But when we utilize Phipps's potential energy together with the classical kinetic energy this leads to an unphysical result.332B6747753