Studies on eaath pressure, in the other words, stresses in the country rock around an underground way and working are very import mt matters, but literatures on this problems treated dynamically are very few, as the underground conditions are very complicated.
Author first analysed the phenomena of earth pressure and then gave stresses in the country rock around a vertical or inclined shaft, assuming that rock is incompressible solid.

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The electrolytic behaviour of gold in the Wohlwill process, where gold is re fined in an electrolyte consisting of a solution of HAuCl₄ with excess of HCl, is very complex, for example, the electrochemical equivalents of both anode and cathode vary to a great extent, seemingly neglecting Faraday's law, according to the electrolytic conditions such as the current density and the temperature of the bath; the current density up to which gold continues to dissove without gas evolution is limited by the electrolytic conditions, and as soon as it exceeds the limited value the anodic solution ceases and the chlorine gas evolution sets in instead, as if the anode suddenly turned, into a passive state; and during the electrolysis finely-divided metallic gold continuously precipitates throughout the solution and consequently the gold content of the slime is very rich.
To investigate the details of these phenomena and to consider the mechanisms is not only valuable for smooth and economical running in practice but is much interesting from the theoretical point of view. Therefore the behaviour of gold was systematically investigated under various conditions, using pure gold electrodes. The relation between electrochemical equivalents at both electrodes and the electrolytic conditions, such as the time elapsed after the beginning of the electrolysis, the current density, the temperature and the initial composition of the electrolyte, were experimentally determined, and the time of the initial appearance of metallic gold was observed. The concentrations of HAuCl₄, HAuCl₂ and HCl at the dynamical equilibrium and anodic potentials were also measured.
In order to explain the results obtained, a theory similar to that of Briggs on copper electrolysis (Trans. Am. Electrochem. Soc. XI, 231, 1921) is suggested, i.e. the two relations,
Au+⊕ ↔ Au· and Au·+2⊕ ↔ Au …
take place at the electrode but not the direct oxidation of Au to Au…(or reverce) as Luther assumed. Then mechanism at the anode is that Au is firstly oxidised electrochemically into Au·, a part of which changes into AuCl'₂ chemically, while the remaining part is oxidised further into AuCl'₄ electrochemically. This mechanism. together with the idea of reaction verocity of the formation of the complex AuCl'₂, explaints sufficiently well all the phenomena met in gold electrolysis.
In the next the dissolution of the anode, the gas evolution, the anode potential and the effect of an alternating current were observed at higher current densities than the limited, and the results were discussed.
The phenomena which seem to be pequliar to gold will possibly be common for all metals giving more than one kind of complex ion as gold.

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