The Billiter’s potential +0.475 V SHE [1,2] is confirmed by new experimental results [3-11].

1. It was found the change of direction of the current between a dropping mercury and a mercury bottom in solutions of redox systems Fe(CN)₆^-3 - Fe (CN)₆^-4 and quinone–hydroquinone at the given equilibrium potential E_equil. = + 0.475 V SHE ± 1-2 mV [3]. The result was confirmed in [12]. At E_equil.> +0.475 V SHE the current flows from the bottom to the dropping electrode and at E_equil. < +0.475 V SHE – in opposite direction [4-7,10]. Electrocapillaty curves were measured by drop-weight-method in these solutions in the range of E_equil.~+0.4 ÷+ 0.55 V SHE with the maximum at E_equll.~ + 0.475 V SHE.
2. A self-recording galvanometer was used to register the current reversal arising between mercury bottom and dropping electrode in solutions of redox systems [6,7,11]. The recorded positive current decreases to zero at E_equil. = + 228 mV SCE (+ 475 mV SHE) and then the negative current increases during continuous dropping of mercury in a solution of redox system quinone - hydroquinone. E_equil. is changed itself since quinone is adsorbed on mercury drops and removed from the solution(A).
3. The current reversal was registered by a recorder between mercury bottom and dropping electrode in acidified solutions Hg₂(NO₃)₂ at adding of complexing reagents (triethanolamine, sodium ethylenediamine tetraacetate, thiocarbamide). The current reversals are registered at the given E_equil.~+ 0.22 ÷ + 0.23 V SCE (~+0.475 V SHE) at the adding of not so strong complexing reagents [10,11].
4. The electrocapillary curves were measured by drop-weight-method (by weight of one drop, B) in these solutions. After passing of electrocapillaty maximum for the reversible electrode Hg₂²⁺/ Hg at E_equl. ~ + 0.22 ÷ + 0.23 V SCE, we obtained the rising branch of electrocapillary curve of the ideally polarizable electrode at less positive potentials (B). The second current reversal was registered E_{equil. ~}+0.190 ÷ + 0.210 V SCE (depending on how strong complexing reagent). This reversal corresponds to transition from a small descending branch of the electrocapillary curve of the electrode Hg₂²⁺/Hg to an ascending branch of the electrocapillary curve of an ideally polarizable electrode at less positive potentials (B). The electrocapillary maximum was also obtained by the drop-weight-method in diluted solutions Hg₂ (NO₃)₂. This is in line with old results [13-15].
5. The increase of the polarization resistance and the change of polarization capacity are found at measurements with different reversible electrodes at the given E_equil. ~ +0.475 V SHE. These effects were also measured on mercury drops in the diluted solution Hg₂ (NO₃)₂. The increase of the polarization resistance can be explained by reaching of chemical equilibrium of half-reactions at E_equil. ~ + 0.475 V SHE [6,7,16].
6. The measurements by immersion method with redox systems and solid electrodes of the second kind confirm the current reversal at E_equil. ~+ 475 V SHE. Immersing small single solid electrodes should be absolutely clean and dry [7,8]. This method is in progress.

REFERENCES:

1.K.J. Vetter, Electrochemical Kinetics, Academic Press, NY, 1967.

2.The Encyclopedia of Electrochemistry. Ed. By C.A.Hampel, Reinhold, NY,1964.

3.A. I.Chernomorskii, Electrocapillary Curve of Nonpolarizable Mercury Electrode in Solutions of Redox-Systems Fe(CN)6-3 - Fe(CN)6-4 and Quinone - Hydroquinone, Soviet Electrochemistry, 1981, 17, 874.

4.A. I.Chernomorskii, Current Reversal at Billiter Potential, Russian Journal of Physical Chemistry, 1981, 55, p.206.

5.A. I.Chernomorskii, Thermodynamics of Reversible Electrodes, FAN, Tashkent, 1982.

6.A. I.Chernomorskii, Thernodynamics of Electrodes, FAN, Tashkent, 1993.

7.A. I.Chernomorskii, The Intermediate Electron Bond and Half-reactions, Scientific Resources, New York, 1999, ISBN 0-9703540-02.

8.A. I.Chernomorskii, Determination of Billiter Potential +0.475 V SHE by the Immersion Method on Electrodes of the Second Kind and Ox/Red- Electrodes, Russian Journal of Physical Chemistry, 1977, 51, 2349

9.A. I.Chernomorskii, Electrocapillary Curves of the Reversible Mercury Electrode, Reports of Academy of Sciences of the Uzbekistan, 1984, 3, 33.

10.A. I.Chernomorskii, The Charge Reversal of Mercury Electrode at Equilibrium Potentials close to +0.475 V SHE, Reports of Academy of Sciences of the Uzbekistan, 1988, 9, 43.

11.A.I. Chernomorskii,N.S.Polizan, Registration of Current Reversal at Billiter Potential Using a Recorder, Reports of Academy of Sciences of the Uzbekistan, 1990, 6, 35.

12.Ya. I.Tur’yan, Redox Reactions and Potentials in Analytical Chemistry,Khimiya, Moscow, 1989.

13.K. Bennewitz, A.Delijanus, Die Electrokappillarkurve des Quecksilbere, Z.Phys.Chem., 1927, 125,144.

14.K. Bennewitz,K.Kucler, Bemerkung zur Elektrokapillarkurve des Quecksilbere, Z.Phys. Chem., 1931, 135, 443.

15.H.J.Oel, H Strelow, Die Electrokapilllaritat der Unpolarisierten Quecksilberelectrode, Z. Electrochem, 1954,58,665.

16.A.I. Chernomorskii, The Correlation Between the Electronegativities and the Standard Potentials, J.Electrochem.Soc.2021,168,116514.