It is endeavored to confirm the mineral composition of Soma Ohori clay, and also to understand its utilization towards porcelain manufactories. Therefore, this study does not intend to pursue respectively the charateristic of mineral composition. The experimental methods employed in this study are as follows: microscopic observation, X-ray diffraction method, infra-red absorption analysis, quantitative chemical analysis.
Summarizing these experimental data, Ohori clay is originated in sedimentary rocks (tuff), and it is composed of clay minerals produced by its transition process towards soil. This olayish soil cotains various clay minerals such as montmorillonite and kaolinite.

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In this study on the carbonation of calcium hydroxide, some fundamental problems in the carbonation of hydrated cement were discussed, and distinctive features in the carbonation of calcium hydroxide were examined. Several species of calcium hydroxide were carbonated with CO₂ gas at a poor coexistence of water (gas reaction), or at a rich coexistence of water (liquid reaction) and examined for a rate of carbonation and for a crystallinity of calcium carbonate in the reacted layer. The results obtained are as follows:
1) A rate equation of the solid state reaction presented in this study has several advantages; the equation can apply to rates of different processes successfully, and the value of n in the equation indicates the rate determing process quantitatively.
2) Rates of the carbonation are differed in the gas reaction and in the liquid reaction. The water quantity coexisting in the reaction influences the crystallinity of calcium carbontae, resulting the porosity difference of reacted layer of specimens.
3) Reactivity of species of calcium hydroxide depends on preparing condition and crystallinity of species, and determine the rate of reaction and species of products.
4) The results on the rate equation and on the difference between gas reaction and liquid reaction obtained in this experiment, will be similarly held in carbonation of the other components of hydrated cement.

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The spinel layer formed through the reaction of the ¹⁸O-enriched MgO piece and the Al₂O₃ piece in an argon atmosphere was analyzed by spark source mass spectrometry. It was found that the concentration of ¹⁸O changes very sharply at the interface of two spinel layers. The ¹⁸O distribution indicates that the MgO-side spinel layer consists of oxygen which comes from the ¹⁸O-enriched MgO piece and the Al₂O₃-side spinel layer consists oxygen from the Al₂O₃piece. These results indicate the growing up of the spinel layers through the interdiffusion of Mg and Al ions in a rigid oxygen lattice of the product. The analysis method of ¹⁸O in solid oxides by spark source mass spectrometry was demonstrated to be an effective technique for the investigation of solid state reactions. All solid state reactions about which incompatible observations were obtained should be re-examined by using ¹⁸O as a tracer.

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The structure of ZnCl₂ glass was studied by X-ray diffraction method and the following results were obtained. In the glassy state Zn-Cl distance is 2.32 Å, and the coordination number of Zn is 4. It is elucidated that ZnCl₄-tetrahedra link each other at their own corners and construct the layer structure similar to γ-ZnCl₂ crystal (shown is Fig. 6). Such model structure is not incosistent with the properties such as melting point, viscosity and etc. Therefore, the structure of ZnCl₂ glass is not so much distinctive and is built up to the network consisting of 4-fold coordinated Zn²⁺ ions. So far as concerning this point, one can find no difference from the well-known structure of conventional glass. Glass-formation range of some binary and ternary systems involving ZnCl₂ as a common component were also studied, which were shown in the Table 6 and Fig. 10.

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