The phase equilibrium study on x (Co₃Al₂Si₃O₁₂)-(1-x) (Y₃Al₅O₁₂) series (x being the weight fraction) showed that garnet was the only stable phase in the composition range of x=0.0-0.30; garnet coexisted with spinel, cristobalite, and Y₂O₃-SiO₂ mineral in the range of x>0.30-0.46; and spinel, cristobalite, olivine and Y₂O₃-SiO₂ mineral were the stable minerals for x=0.49 (T. Noda and M. Ushio, this journal, 75, 330 (1967).
In the present paper, the pressure effect on the stability region of garnet or other minerals of this series are reported. Glasses or gel mixtures corresponding to x (Co₃Al₂Si₃O₁₂)-(1-x) (Y₃Al₅O₁₂) series (x being the weight fraction) were heattreated at pressures up to 40 kbar, using a sgeezer or a modified girdle type high pressure apparatus.
The increases in temperature from 385° to 800°C and in pressure up to 40 kbar resulted in the extension of the region of garnet formation to a larger value of x. At relatively lower temperatures, however, the x-value of garnet formation region was not found to exceed a certain value even if high pressure was applied. Cobalt garnet proper could not be synthesized below 800°C at pressure even above 25 kbar. As was already shown, dp/dT for the reaction of cobalt garnet formation was positive, and even in the stability region of the garnet, reaction of the garnet formation hardly proceeded at temperatures below 1000°C (T. Noda and M. Ushio, this journal, 75, 125 (1967)).
The results obtained in the present experiments that the x-value of garnet formation region increased with the increase in temperature are probably due to the sluggish rate of reaction at low temperatures. Therefore, the observed region of formation is not considered to be in the true equilibrium state.
With heat treatment at 1200°C cobalt garnet was obtained at pressures above 21 kbar. The x-value of the garnet formation region increased almost linearly with increase in pressure. The experimental results obtained at 1200°C are likely to show relationships in the equilibrium state.

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Dielectric properties of electronic conduction oxide glasses containing Fe₂O₃ or WO₃ were studied by the D. C. and A. C. measurments (10^-1-10^-6c/s) in the temperature range from 0° to 200°C. Though the conduction of these glasses is electronic, the time dependence of currents is found for the glasses at lower temperatures. The time dependent currents show Ohmic characteristics, and both charging and discharging currents decrease with time and the decay characteristics of the currents are identical. The dielectric absorption curve calculated from the time dependent current by Hamon's equation is smoothly linked with that obtained by A. C. measurment in higher frequency range. These facts suggest that the origin of this time dependent current should not be attributed to the space charge polarization but be attributed to the dielectric relaxation measured as a dielectric dispersion (or absorption) in higher ranges of temperature and frequency.
The activation energy for dielectric relaxation is nearly identical with that for D. C. conduction. And there is a correlation between the D. C. conduction and the dielectric dispersion (or absorption) as follows;
σ_??_ε₀⋅Δε⋅2πf_max.
where σ is the D. C. conductivity, ε₀ the dielectric constant for vacuum, Δε the magnitude of dielectric dispersion and f_max the frequency at loss maximum.
The Cole-Cole parameter β for representation of the distribution of dielectric relaxation times varies the range from 0.55 to 0.60, has an weak dependence on the composition of glass, and is independent of temperature.
Both of these experimental results and the previously reported evidence for the low frequency dielectric relaxation in ionic conduction glasses lead to the conclusion that the nature of the low frequency dielectric relaxation in electronic conduction oxide glasses is identical with that in ionic conduction glasses.

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Al chlorite-montmorillonite like layer mixed clay minerals which are important component of UEBI stone and IZUSHI stone are discribed. UEBI stone in Ehime prefecture was used from 50 years ago in porcelain industry, IZUSHI stone in Hyogo prefecture has been the chief material of porcelain in Kyoto and in Izushi during about 2 handred years. These stone are characterized by their very high plasticity. The refined materials which were obtained by washing these stone are investigated mineralogically by X-ray analysis, differential thermal analysis, chemical analysis, infrared analysis etc. These results are as follows:
1. X-ray analysis
Basal spacing d₀₀₁ of the chief clay mineral from UEBI stone and IZUSHI Taniyama and their replace by various treatments are tabulated in the next:
2. Differential thermal analysis curves of UEBI stone and IZUSHI taniyama stone have the almost same pattern that has enothermic peaks at 160°C, 230°C, 530°C, and 630°C and exothermic peaks at 910°C and 970°C. IZUSHI Kakitani and Hinobe have further endthermic peak at 560°C due to kaolinite. These results show that the chief clay minerals of the stones are the regulermixedlayermineral which is resemble to Sudoite-montmorillo nite regulermixedlayer. (Tosudite).
3. These stones contain another mixedlayermineral which is specifid by the basal diffraction of 10.8 Å after treatment of NH₄NO₃. This mineral seems to be sericite-montmorillonite non regulermixedlayer.

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In order to make large Mg(OH)₂ crystals of high purity, Mg²⁺ ions were diffused into controlled alkaline starting medium by using pH stat via a ceramic membrane.
Experiments were conducted under the following conditions: Starting medium: Stagnant NaOH solutions and stagnant calcined dolomite solutions, the pH values of which within 9.0-12.0. Concentration of additives: N/50-N/20. Addition rates: 0.5-3.0cc/hr. Diffusion reaction temperatures: 30°-60°C. Overall times of diffusion reaction: 7-14 days.
The principal results obtained were summarized as follows:
1) The pH values of starting medium: 10.0-11.6, Concentration of additives: N/50-N/30, Addition rates: 1.0-2.5cc/hr, Temperatures: above 40°C, Time: 10 days.
In the case of above conditions the size and shape of produced Mg(OH)₂ were improved, the maximum size about 1mm, and the yield above 60% were obtained.
2) Mg(OH)₂ obtained under the following conditions were often tiny crystals. pH values of starting medium: above 12.0, Concentration of additives: above N/20, Addition rates: above 3.0cc/hr.
3) When diffusion reaction times were too short, crystal growth were not enough, and when too long, produced Mg(OH)₂ were often irregular overlaps.
4) Mg(OH)₂ obtained by the combination of NaOH starting medium with Mg reagents were high purities, while by the combination of starting medium of calcined dolomite solution with sea waters, they mainly contained impure Ca.

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