Disintegration of Magnesium While Dissolving Anodically in Neutral and Acidic Solutions

Abstract

A closer investigation of the dark deposits which separate from a magnesium anode in the form of leaflets in neutral and in acidic solutions showed that the views set forth by Baborovsky (1905) concerning metallic Mg in the deposits are correct. A multitude of Mg particles of about in diameter were visible in the flakes, causing their dark color. In perchloric acid the magnesium anodes first turned slightly dark at the rim. Beautiful patterns of deformation twins appeared. At high current densities flakes containing innumerable metallic particles separated from the anode. The particles broke off from anodic regions leaving a series of dark holes where the metal was locally strained or deformed or where the interatomic bonding was weakened. The partial disintegration of Mg into fine particles contributes to the explanation of the negative difference effect; it explains the apparent deviation from Faraday's law and shows that the assumption of expulsion of lower valency ions from the anode during anodic dissolution is unnecessary at present. The active metal particles themselves have great reducing ability.