On the assumption that the sodium disilicate glass is composed of a great number of cells which can contain single discrete molecule, the temperature dependence of the volume of this glass is investigated on the basis of thermostatistical calculation, where an approximate form is assumed for the potential function between a pair of nonbridging oxygens each belonging to two discrete ions neighbouring to each other. The mean distance between a pair of discrete ions and the single and pair distribution function are calculated on the basis of this potential function. In consequence it is shown that the glass transformation is essentially due to a feature of potential function that it rises abruptly at an ion-distance a little larger than the minimum point compared with a Lennard-Jones' type function which is used as an approximate potential function in the smaller region than that point. Finally the temperature dependence of the volume of the real glass is discussed.

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The new compounds of two types (high temperature stable form and low temperature stable form) were found in the system of 2CaO⋅SiO₂-3CaO⋅B₂O₃. The molecular formula is 11CaO⋅4SiO₂⋅B₂O₃ and their lattice lengths are a 10.65Å, b 55.43Å and c 6.89Å for high temperature stable form, and a 31.96Å, b 55.20Å and c 6.83Å for low temperature stable form as orthorhombic. These two forms may perhaps have the similar structure to α′-2CaO⋅SiO₂, but make a quite different unique compound. 3CaO⋅B₂O₃ was synthesized and the lattice constants and the crystal system were investigated as a 14.96Å, c 1.86Å and the space group P31 c or P31 c as trigonal. Finally the phase equilibria among these compounds were investigated.

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As basic compositions, 15Na₂O⋅85SiO₂ (Na glass) and 25Li₂O⋅75SiO₂ or 30Li₂O⋅70SiO₂ (Li glass) were selected and the effects of addition or substitution of the components such as MgO, CaO, BaO, ZnO, CdO, PbO, Al₂O₃, B₂O₃, TiO₂, ZrO₂, SiO₂, GeO₂ and P₂O₅ on miscibility temperature (T_m), viscosity, texture of phase separated glass etc. were examined.
The addition of small amount of the divalent components lowered T_m of Na glass in the order CaO<BaO<CdO<ZnO<MgO<PbO. But even in the case of CaO the introduction to the amount contained in commercial soda-lime-silica glasses (e. g. sheet glass) prevented the phase separation occurring. Among the polyvalent components, the effects of P₂O₅ and Al₂O₃ on T_m were especially remarkable, the former raised and the latter lowered it. B₂O₃ lowered T_m at first and then raised it with increasing amount of the addition, for viscosity B₂O₃ gave reverse change, though. In the glasses added the components which raised T_m, the interconnected two phase structures were liable to be observed after heat treatment. Similar results were also obtained in Li glass.
It was showed from the plot of T_m of 15Na₂O⋅85SiO₂+2.5RO_x glasses against ionic field strength of added cations that (i) in case of the network modifiers, T_m rose with increasing ionic field strength of added cation, (ii) this was also true for network formers, but (iii) this relation became inverse for intermediates. The possible reason was discussed from the point of the effects of added cations on the compatibility between SiO₂ and Na containing phase.
Moreover it was pointed out that the chemical durability was low in the glass with high T_m.

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Grain growth in vacuum sintering of thermally decomposed alumina from aluminum sulfate was observed.
Two series of specimens, i.e. with and without addition of 0.05wt% MgO were prepared. Specimens were sintered in the temperature range from 1550° to 1700°C and from 15 to 120 min.
The results obtained were as follows:
1) Grain growth of specimens with MgO can be expressed as the following equation:
D-D₀=Ktⁿ
The value of n obtained in this experiment was 0.31. The activation energy for grain growth obtained from Arrhenius plot was 155kcal/mol.
2) For the series of specimens without MgO exaggerated grain growth was observed in firing at 1550°C for more than 30 min and at temperatures above 1600°C for more than 15 min.
3) For specimens in which exaggerated grain growth was occurred locally, any normal grain growth was not confirmed in other part of the observed area.
Large crystals resulted from exaggerated grain growth were estimated to complete their growth in an earlier stage independently.
4) The areas where large crystals appeared first were in accordance with the area of the highest density in green specimens.
5) The critical point for exaggerated grain growth seemed to be that the closed porosity of specimens reached to about 6%.
6) When the specimens with local large crystals were reheated in vacuum after adding a small amount of MgO, the large crystals held their own shape and size, while in the area other than large crystals normal grain growth occurred in the same way as in the specimen containing MgO from the beginning. And these grains were much larger than those of the latter.

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