III. Effect of chlorine on the electromotive force of a voltaic couple

Abstract

If the electromotive force of a small voltaic couple of unamalgamated magnesium and platinum in distilled water, is balanced through the coil of a moderately sensitive galvanometer of about 100 ohms resistance, by means of that of a small Daniell’s cell plus that of a sufficient number of couples of iron and German silver of a suitable thermoelectric pile (see ‘Proceedings of the Birmingham Philosophical Society,’ vol. 4, p. 130), the degree of potential being noted; and sufficiently minute quantities of very dilute chlorinewater are then added in succession to the distilled water, the degree of electromotive force of the couple is not affected until a certain definite proportion of chlorine has been added; the potential then suddenly commences to increase, and continues to do so with each further addition within a certain limit.