The effect of superposed alternating current on the polarisable primary cell zinc-sulphric acid-carbon. Part II.—High frequency current

In Part I of this investigation, It was shown that, when alternating currents of frequencies between 20 and 400 per second are passed through the primary cell zinc-sulphuric acid-carbon, the depolarisation and increase in current output first observed by Brown, are essentially due to an effect produced at the carbon electrode, the potential of which becomes more positive by an amount depending on the strength and frequency of the alternating current used. The greater this current and the lower its frequency, the greater the effect, a result quite in line with what was already known on the subject of the action of, superposed alternating currents on polarised electrodes. Brown had, however, also obtained a marked action when using a current of 12000 periods, and had ascribed it to an effect produced at the zinc electrode. The results of Allmand and Puri indicated that such high-frequency current would be unlikely to depolarise the carbon electrode perceptibly. In addition, the anodic solution of zinc is usually regarded as occurring almost reversibly, although Allmand and Puri had certainly noticed a small depolarising effect caused by their low frequency currents. Consequently, the results reported by Brown with a frequency of 12000 appeared to merit further investigation, and the present paper contains an account of experiments to this end.