A New Determination of the Faraday by Means of the Silver Coulometer

Abstract

Of the several electrochemical determinations of the Faraday constant, most of them done at the National Bureau of Standards (1, 2), the experiment usually cited is that of Craig and his collaborators (1). This experiment exhibited a model concern for detail and moreover showed a somewhat higher precision than the measurements of oxalic and benzoic acids (2). Craig’s measurement employed the electrochemical dissolution of silver into perchloric acid as its principle. He dissolved a highly purified sample of silver anodically into an acid which did not attack silver unless current flowed. Such obstacles to a reliable measurement as electrolyte inclusions in the silver and segregation of the silver isotopes by electrolysis were thus avoided. By separation of the cathode and anode compartments he assured the retention of all debris which inevitably falls from the ingot of silver during the electrolysis.