The high temperature modifications of Ca₂SiO₄, free from stabilizers, cannot be quenched to room temperature, and the high temperature X-ray diffractions of the modifications, reported by many authors, are obscure, and cannot be analyzed. On the other hand, the powder X-ray diffractions of many minerals, natural and synthetic, reported as solid solutions of the respective modifications, do not coincide each other.
In the previous paper, the authors reported the high temperature X-ray diffractions of pure Ca₂SiO₄ over the temperature range from 25° to 1550°C, which were sharp enough to be detected the characteristic profile of the each modification.
In this paper, the authors report the more precise powder X-ray diffractions of the modifications quenched to room temperature and adding suitable stabilizers, which are usually contained as miner components in commercial portland cement clinkers. The diffraction patterns of the samples coincide to that of high temperature X-ray diffractions of the each modification, and the intensity and the spacing of the diffractions fully coincident to the structure factor (F hkl) and the spacing (d hkl) respectively, calculated from the each structure model, assumed by isomorphic studies of M. A. Bredig.
From this study, the powder X-ray diffractions of each modification are reliably determined, and the assumptions on the crystal structures are justified.

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In the bubbling process in glass melting the gas is blown out through the liquid of high viscosity with a considerable velocity and being under the rule of hydrodinamics, the estimation of the size of bubbles by theoretical calculation will be very difficult.
The authors, therefore, carried out the model experiments in order to establish the relations between the size of bubbles at the mouth of nozzle inserted vertically into the molten glass, and the gas velocity, the physical properties of glass, and the nozzle diameter.
In the first place the authors determined the dimensions of cold scale model satisfying the conditions of similitude using the method of dimensional analysis.
As the model liquid millet jelly was used, and the surface tension and the density of glass were assumed to be 300 dyne/cm, and 2.5g/cc respectively. The experiments were carried out under the conditions; viscosity 100-400 poise converted to actual furnace, flow volume 20-65cc/sec, nozzle diameter 0.5-10mm.
The results showed qualitatively but clearly the profound influence of flow volume of gas and the viscosity of glass on the size of bubble. Moreover, it was found that the experimental results could be divided into two groupes bounded by Ih=50, which is a non dimensional term given by the ratio Froude/Raynolds numbers, and represents the influence of bouyancy and viscous force.
Using these experimental formulas the relations between the size of bubble and the factors were made into tables.
Also it was confirmed that the size of bubbles in the prototype were in good agreement with the calculated values using the experimental formulas.

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The temperature changes in the melting basin of a tank furnace having 43.5 sq. meter of melter area were measured continously and recorded during operation at various points and depths, and some dynamic relations between temperature variations of molten glass and operational variables of furnace were found. The author proposed a equation govering the thermal balance in basin and showed every change of components of this equation with furnace load. With regard to the change of average temperature level of glass in the basin, there is a tendency to shift to the lower side with increasing pull. He also pointed out that the continuous detection of glass temperature in basin can be the most useful mean in keeping the safty operation of furnace under high load. Concerning the mode of main convection current cycle in basin, there are several evidences which prove the single cycle, that is, charging cycle is dominating in stead of double in case the melter is covered over 60% with batch, and also it was found the homogenization of glass takes place chiefly in the area between batch line and bridge wall. Relations between temperature distribution of combustion chamber, melter basin and mode of convection current were discussed and some considerations for the more efficient operation of furnace was made along this line. The performance figure obtained by this furnace is as follows: melting rate: 2.9 ton of glass per sq. meter of melting area, fuel rate: 164 litre of heavy oil per ton of glass produced per day. (ton: metric)

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There are some papers concerning the influence of MgO on the strength of blast furnace cement using synthetic slag containing different amount of MgO. And up to 5-10% MgO no decrease in strength but instead some inclease in long term strength was observed leading to the conclusion that MgO would be plying the similar roll to CaO. This method is practical but will make the problem complicated.
The authors, have prepared 5 samples of glassy slag containing stimulating agents and different amount of MgO to study the hydraulic properties in room temperature and in autoclave.
(1) Hydration in room temperature
Next to gehlenite (J. Ceram. Assoc. Japan, 68, 307, (1960)) the progress of hydration of a knid of melilite, and of akermanite added as stimulant Ca(OH)₂ and CaSO₂⋅2H₂O was studied. The crystalline substance found in the hydration product of melilite was similar to that of gehlenite, whereas no crystalline phase was obtained in the hydration product of akermanite.
Up to 28 days the amount of hydration of both samples was 50-55% giving no profound difference. As far as the present experiment concerns no sharp difference between the hydration of the two species was observed except the separation of the crystalline substance.
(2) Hydration in autoclave
The same samples were hydrated under pressure. The conditions were; temperature, 100°, 125°, 150°, 175°C; time 0.5, 1, 2, 4, 8 hrs.
The strength of the hydrationproduct at 100°C increased with increasing Al₂O₃ content, and the reaction of CaO ran parallel with the amount of Al₂O₃. In this case CaO-Al₂O₃-H₂O was found to be main reaction product.
On the contrary, at 125°C the strength showed a marked fall with increasing Al₂O₃, which might due collaps of the strength revealing product of the system CaO-Al₂O₃-H₂O.
The hydration at 175°C the strength increased with increasing Al₂O₃, where the principal crystalline hydrate was found to be as 3CaO⋅Al₂O₃⋅SiO₂⋅4H₂O (Kalousek, J. Am. Ceram. Soc., 40, 74, (1957)).
The samples containing more MgO showed generally low strength, which increased monotonausly with temperature and time. The addition of 20% crystalline silica powder, however reversed the trend giving higher strength with increasing MgO content.
In these cases the hydration product was amorphous. In the eyes of composition Al₂O₃ was effective as a strength developing agent when only basic stimulant was used, but with the addition of SiO₂, MgO became more effective.

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