Sintered specimens were prepared from the ingots of fusion cast dunite obtained by the methods descrived in the previous papers (J. Ceram. Assoc., Japan, 68 [10] 237 (1960); J. Ceram. Assoc., Japan, [12] 294 (1960)), and their appearance and thermal properties were investigated.
The specimens made from dunite alone or from the mix added with MgO secured the stability under load at high temperatures when the mol ratio MgO/SiO₂ of the ingot was larger than 2.
In the case of the ingots added with Al₂O₃ the same result was obtained when the composition represented on the triaxial diagram MgO-Al₂O₃-SiO₂ was richer in MgO than the line connecting the points MgO⋅Al₂O₃ and 2MgO⋅SiO₂.
Dissociated from the composition of the ingots all specimens gave the thermal expansion of about 1% at 1, 000°C without showing any anomaly. As the thermal conductivity was smaller than ordinary basic refractories the author expects the practical use of the above sintered bricks for the ceiling of industrial furnaces.

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Studies have been made on the problems of the glass formation range, which are important as the fundamental data for the science and industry of glass, and the systematic investigation of which has never been carried out.
Borate systems were studied using, except B₂O₃, the oxides of 16 a-group elements-Li, Na, K, Be, Mg, Ca, Sr, Ba, Al, La, Ti, Zr, Th, Nb, Ta, W-and 9 b-group elements-Zn, Cd, In, Tl, Sn, Pb, As, Sb, Bi-to combine into 266 ternary systems in all. The other combinations were regarded as having no glass formation range.
The experimental results were compared with the glass forming ranges which may be expected from the conditions of glass formation given by the author (this journal, 67, 364, 1959) with a result that both are, in general in good agreement.
It was found that the glass formation range will be limitted by following conditions:
i) The limit of one dimensional continuity of the network structure. It depends on the coordination number of network former, and whether the coexisting component takes the position of modifier or enters into the network. In the former case the type of glass formation range is represented by the point A or B, and in the latter case D or E on the triaxial diagrams shown in the text.
ii) The limit comes from the condition of network formation. According to the condition of glass formation iv (see below), a limitting point may be given from the difference between the valency and the coordination number of network formers. It is the point C on the triaxial diagrams.
iii) The limit of the number of modifier ions. The limit of the number of modifier ions which enter into the glass network is given by the radius of network formers. The relations are shown in Fig. 9.
iv) The limit of the substitution of network formers for B³⁺ ion. Point X in the triaxial diagrams shows this limit. It is highly probable that this limit depends on the radius ratio of network formers and modifiers, although this point does not correspond to a deffinit type of glass structure. In the case of b-group ions, which can form a glass structure by themselves this point corresponds with the limit of the continuity of network. It is shown by the points P, Q, R, ....in the triaxial diagram.
Although there are many exceptions and special cases it is the general trend that the mixed systems of similar components, such as mixed alkalies, enlarge the glass formation range.

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In the manufacture of ceramic piezoelectric vibrators the process should be that of giving the uniform packed bodies in order to avoid, as far as possible, the strain due to the local nonuniform shrinkage at the firing, and the variation of elastic constant from point to point.
For the purpose of establishing the method of producing ceramic piezoelectric vibrators, the authors have carried out a systematic experimental studies with the following results:
i) The authors were able to formulate the experimental data to an expression which represents the relation between the pressure and the strain during the pressing.
ii) The distribution of pressure and density in the pressed bodies of BaTiO₃ and TiO₂ were investigated in detail with a result that the method of cutting off the part having comparatively uniform density from a cylinder formed by pressing will give an article with the minimum deformation during the firing.
iii) It was proved that hydrostatic pressing is the good method for giving a body having the uniform density distribution.
iv) The piezoelectric vibrators made by the method given above did not show the separation of resonant frequency.

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For the purpose of throwing light on the action of transition elements in glass, and making clear the influences on coloration, the authors carried out the investigations on the coloration of vanadium containing glasses.
Using the base glasses of silicate, borate, and phosphate systems the coefficient of transparency between the wave lengths of 300-1, 100mμ were measured.
Four absorption bands, i.e. in ultraviolet region, 425-450, 625-710, and 900-1050mμ were observed. Systematic studies were carried out in order to know the change of absorption bands due to the variation of glass composition, vanadium content, melting temperature and atmosphere, and the condition of heat treatment, and the experimental results were interpreted in terms of the change of the valency of vanadium in glass.
A reversible color change was observed at a temperature between 200°-300°C, and the corresponding change of the coefficient of transparency was investigated. In vanadium containing glasses there may exist a mechanism like a lattice deffect under certain condition which is closely related to the reversible color change.

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