Die Theorie der Alterung eines schwerlöslichen Niederschlags wie AgBr durch Umlösen entsprechend der höheren Löslichkeit von kleinen Teilchen gegenüber derjenigen von großen Teilchen wird quantitativ entwickelt. Es werden Gleichungen für die zeitliche Änderung der Größen‐Verteilungsfunktion, der mittleren Teilchengröße und der Teilchenzahl bei diffusionsbestimmtem und bei reaktionsbestimmtem Stoffübergang mitgeteilt.

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Electromotive force measurements on galvanic cells involving solid electrolytes have been made in order to obtain the standard molar free energy of formation of CoO, NiO, Cu~O, AgeS, Ag~Se, PbS, and several phases of the system Ag-Te at elevated temperatures.Haber and Tolloczko (1), Katayama (2), Reinhold (3, 4), Treadwell, Ammann, and Zfirrer (5), Croatto and Bruno (6), Rose, Davis, and Ellingham (7), Sator (8), and others have shown that emf measurements on galvanic cells involving solid electrolytes may yield valuable thermodynamic data. The following investigations have been made in order to show new potentialities of emf measurements on galvanic cells involving solid electrolytes for the determination of the standard molar free energy of formation of oxides, sulfides, selenides, and tellurides at elevated temperatures.

The total electrical conductivity and the electron hole conductivity in solid CuCl, CuBr, and CuI between 250 and 450°C have been determined with help of ac measurements on samples between copper electrodes and dc polarization measurements on the cell Cu|cuprous halide|graphite.

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