Lead electrodes were anodically etched in NHpS03H. Immersion potentials, self-passivation potentials, passivation times, PbO?/Oa potential, and the potential of the first discharge plateau were determined in H?SO( solutions ranging from 0.5 to 30.0 N and were found to be concentration-dependent. Interruption of the anodizing current had no detectable influence on passivation time. Data obtained with the anodizing current turned on fall into three categories; those obtained with (1) short-immersion anodes, (2) anodes which had reached a hydrogen-like potential, and (3) anodes which were self-passivated before the current was switched on. AII inflection in the relation between potential and time during charging was investigated. Its length was dependent upon acid concentration and current density, while its potential was +300 & 30 mv, and seemed to correspond to the self-passivation potential. T h e lengths of the first and second discharge plateaus increased with the nr~tnber of coulombs passed and were dependent upon acid concentration, but were identical for electrodes treated by four different methods. The hydrogen-like poteritial appeared to be due to the presence of PbO. PbSOr. The self-passivation potential seemed to be caused by for~nation of PbO.
An attempt was made to clarify the question whether the variation in the length of the "first discharge plateau" with change in HzSO4 concentration wascaused by a change in the efficiency of PbO, formation or by a variation in its discharge rate. The relationships between acid concentration, "passivation time", amount of PbSO, formed during passivation, and the quantity of PbOz derived therefrom during charging were investigated. The amount of PbS04 on the anode increased with a decrease in passivating acid concentration. More PbO, was formed at lower charging acid concentrations. The higher the discharge acid concentration, the greater was its stabilizing effect on PbO, discharge. The combination of two factors, i.e. a decrease of the amount of PbO, formed at higher acid concentrations together with an increase in the PbO, stability, gave rise to the maximum 10.5 N H2S0,.
The polarization-time relations for the initial ( P i ) , maximum (P,,), and pseudo-steady-state (P,) polarizations on copper single crystals in the absence and presence of gelatin and gelatin plus chloride ion were found t o depend upon crystal orientation. The P i and P, , , in the absence of gelatin, the Pi in its presence, and the static potentials were all similarly related to the reticular density. The P i increased, and the time to masimum polarization (t,,,,) decreased, with increase of current density; the relations between these quantities showed marlced differences for the different crystals. The variation with reticular density of Pi and P, , , in the absence of addition agents and of Pi in its presence probably represents differences in activation overpotential a t the various crystal faces. The adsorption of gelatin on different crystal faces was also found to be markedly different. Polarization in the presence of gelatin was decreased by small amounts of chloride ion; a linear relation for all the crystals used was obtained by plotting the increase in polarization caused by gelatin against the decrease caused by 2 mgm./liter chloride ion in the presence of gelatin. In the absence of addition agent, change of acid concentration from 50 to 200 gm./liter had no effect on P i and addition of chloride ion had no effect on P , a t single crystal cathodes.
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