The Chemistry of Electroplating

Wilder D. Bancroft
1904 The Journal of Physical Chemistry  
Although some results have been obtained by Mylius, Foerster, Glaser, Burgess and others, a glance at the recent textbooks on electrochemistry will show how far we still are from any consistent theory of electroplating. The reason for this is to be found in our neglect of the chemistry involved. The electric current is merely one agent for bringing about certain chemical reactions ; but this is often overlooked and @any of us consider a decomposition by means of electricity as much more
more » ... s much more mysterious than a decomposition by heat, for instance. I hope to show that a study of chemical reactions and chemical analogies will at least give us the outlines of a theory of electroplating. When we speak of a good metallic deposit we may mean good from the point of view of the analyst, the refiner, or the plater. The analyst must have a deposit of pure metal in a weighable form but that is all. The refiner must have a coherent deposit of pure metal, except in the case of silver. Keither the analyst nor the refiner cares about the smoothness of the deposit in the sense that the plater uses the word though the refiner is happier the smoother the deposit is. The plater must have an adherent smooth deposit which will burnish to an apparently amorphous surface. In the preliminary discussion we will rule out the plater and will call a deposit good when it is pure, coherent and free from trees. Afterwards we can consider the further problem of the production of a very fine-grained deposit. Since there are very few data for anything except aqueous solutions, we will consider these only, though the general principles are equally applicable to all solvents. When working with moderate current densities a bad deposit is practically always due to the precipitation of a compound of the metal with the metal. When one of the single A preliminary abstract of this paper was presented a t the International Flectrical Congress of St. I,ouis, 1904, b
doi:10.1021/j150067a001 fatcat:xag37aayhndfthffu4dkj2c2be