“The electrical charges on Mercury drops in sulphuric acid and other solutons”

Abstract

Mercury drops falling vertically through an electrolyte may be deflected from their course by application of a horizontal field in the electrolyte. A method of photographing the curve followed by any drop is described, and it is shown possible to deduce the ionic charge on the drop from a study of the shape of the curve. In Sulphuric acid of fixed concentration the drop charge is found to be proportional to its volume. Results are also given for the charges in various acid concentrations between 0.1N and 0.001N. All charges are found to be reduced when the acid is saturated with mercurous sulphate. This seems to afford evidence that, in acid, the charges are due to hydrogen ions, and not to mercurous ions as had been assumed by several investigators. Results obtained in other electrolytes are also given. Some remits for drop charges, measured by a ballistic galvanometer method, are included for comparison. The method is less accurate but confirms the original results. A description is given of similar experiments with amalgam drops. Silver amalgam is similar in behaviour to pure mercury, but Cadmium and Zinc amalgams show a curious phenomenon. The drops are naturally positive, but their charge may be reversed in sign by application of a 'sufficiently strong field. A possible explanation of this, effect is discussed. Some attention is given to the fact { that Zinc and Cadmium appear naturally positive. Several results showing charges in various potential gradients, and. for amalgams of various compositions, are included. A few final pages are devoted to similar experiments using air bubbles and the possibilities of the method for cataphoresis experiments. [brace not closed]