Anodic processes. Part VI. The photomicrographic method. Application to the mercury–aqueous hydrochloric acid system

Abstract

A photomicrographic method is described for the examination in situ of anodically generated films upon the surface of a mercury electrode in contact with purified, deoxygenated electrolyte solutions. The method has been applied to the study of the formation of calomel films in the mercury–aqueous hydrochloric acid system. The course of a typical, low current density anodisation is described. The influence of variation in current density, of acid concentration, and of the presence of the disproportionation products of calomel are demonstrated and briefly discussed. Observations are made of the non-electrolytic deposition of calomel, and of its continued generation at a “passivated” electrode.