The following is a paper by H. Aspden published in Journal of the Franklin Institute, v. 287, pp. 179-183 (1969).
Abstract: The indeterminate state of the empirical law of electrodynamic action between current elements is reviewed. It is shown that a form of law fully consistent with experiment can be deduced from simple Newtonian dynamics. This law points to anomalies to be expected in electrodynamic interactions between electric particles of unequal charge-mass ratio. This result may account for certain hitherto unexplained anomalies in electric discharge phenomena.