We have investigated thermodynamic properties of binary mixtures of 1, 3- or 1, 4-dioxane-cyclohexane, to discuss the isomer effect to the thermodynamic properties. The expansion factor, α of mixtures are required for estimation of excess isothermal compressibilities, κ^E_T and the κ^E_T excess isochoric heat capacities, C^E_{V, m}. Normally, excess expansion factor, α^E is negligibly small and then has been assumed to be zero in calculation of κ^E_T and C^E_{V, m}. However, we found that the contribution of α^E to κ^E_T and C^E_{V, m} is not negligible in case of polar mixtures. We report α^E of 1, 3- or 1, 4-dioxane-cyclohexane mixtures determined from density measurement at 298.15 and 303.15K and discuss the contribution of α^E to κ^E_T and C^E_{V, m}.

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The effect of water vapor pressure on the kinetics of the thermal dehydration of some formate hydrates was studied by means of isothermal gravimetry under various water vapor pressures from 6.7×10^-2 to 1.33×10³Pa. The rates of dehydrations of Zn, Y and Er formate dihydrates exhibited an unusual dependence upon the water vapor pressure; with increasing water vapor pressure the rates increased at first, passed through a maximum, and then decreased gradually to a constant values. These unusual phenomena were analogous to the Smith-Topley effect. On the other hand, the rates of dehydrations of Mg, Mn and Co formate dihydrates decreased with increasing water vapor pressure as was naturally expected from the equilibrium theory.
The mechanism of the unusual phenomena was discussed in correlation with the crystallinity of the dehydrated products.

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The low energy excitation (LEE) mode measured in superionic conductors and the study by the low temperature heat capacity are discussed. The neutron inelastic scattering observed the LEE mode in Ag, Na and Cu ion conductors. The observation of the heat capacity offers an important information to specify the LEE in the superionic conductors. This mode might be one of the characteristic featuresof superionic conductors. Namely materials which show the superionic property in the high temperature phase exhibit the characteristic feature of the LEE mode in its low temperature phase. The characteristic features of the LEE mode are investigated theoretically.

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