Viscosity of the melt assumed to exist at the time of portland cement clinker formation was measured in the temperature range 1350°-1550°C, and the mechanism and kinetics of dissolution of CaO and 2CaO⋅SiO₂ into the melt were investigated.
1. The viscosity of the melt increases with the addition of 3CaO⋅SiO₂ and 2CaO⋅SiO₂ but decreases with the addition of CaO. The relationship between the viscosity and reciprocal absolute temperature can not be regarded as linear, over a wide temperature range. This fact may be resulted from the structural change of melt.
2. Dissolution process is considered to be controlled mainly by diffusion in the melt, though a number of small particles are observed in the diffused zone.
3. It is confirmed that the diffusion coefficient calculated from the rate of reaction which is assumed to be controlled by diffusion in the melt coincides approximately with the values obtained by other methods.

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In recent years, considerable interest has developed in the conversion of high-purity magnesium oxide of sea-water origin into dense crystalline periclase. This periclase has found increasing use in such applications as refractory materials, electrical insulation in heaters and electronics parts.
At the present time, most high-purity periclase is manufactured either by the fusion of magnesia in an electric arc or by heating the magnesia in a furnace at 1800°C or higher.
Periclase, however, has the nature susceptible to hydration and this deteriorates the quality of periclase.
The initial objective of this study was to evaluate the hydration resistance of fused magnesia by autoclaving at 9 atm for 3 hr. The samples used were grains (125-250μ) obtained by grinding and screening, after crushing the electrically fused magnesia blocks.
But the autoclave tests revealed that there was a fairly great dispersion in the weight increases by hydration among the samples of all the same kind, even in the very same batch.
That is to say, the experimental results showed that the reproducibility of the weight increases by autoclaving on fused magnesia was very poor.
Accordingly, an investigation was conducted of certain factors which influence this dispersion of values of hydration by autoclave test on fused magnesia. In the process of series of test, these facts were observed that a disturbance of water and steam occurred during operation in an autoclave, the degree of the disturbance was different according to every location in the space inside the autoclave, and the reproducibility of disturbance was also very poor.
By this disturbance, in the tests of open method using crucibles as sample vessels, some samples were dipped in water and some got wet during operation and the samples dipped or wet with water resulted in low values of the weight increase by hydration, compared with ones which were not dipped or wet, thus being hydrated rather in dry conditions.
On the contrary, in the static hydration tests such as the glass-tube tests or the dipping tests in water, the dispersion of the weight increases by hydration was very little, as was to be expected.
But the hydration test by saturated vapor at room temperature revealed the abnormally great dispersion of the weight increases, contrary to our expectation. It may probably be due to the condensation of water in some samples, because of the fluctuation of room temperature and this fact also suggests the difference of the effects to hydration on fused magnesia between water and steam.
From these experimental results, the main factor that influences the dispersion of values of hydration by autoclave test on fused magnesia, is probably the complex disturbance of water and steam occurred inside the autoclave during operation.

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Nucleation and crystal growth in fluor-richterite composition glass were studied by the electron and optical microscopy and X-ray powder diffraction method. The following results were obtained.
1) As evidenced from a greater number and a smaller size of crystallites, the apparent nucleation rate was larger in the glass sample that was subjected to the heat treatment for glassy phase separation before being subjected to those for nucleation and crystal growth than in the sample that was not subjected to the heat treatment for the phase separation.
2) The temperature corresponding to maximum rate of nucleation of fluor-richterite was in the range from 725°C to 750°C for the glass subjected to the phase separation heat treatment and at 763°C for the glass not subjected to the heat treatment. The apparent activation energy for the nucleation was 110kcal/mole in the former case and 66kcal/mole in the latter.
3) The rate of crystal growth of fluor-richterite was maximum at 1000°C and activation energy for the growth was 142kcal/mole.
4) Two glassy phases formed by the glassy phase separation and a crystalline phase (“fluor-talc”) were present in the sample heat-treated at the temperatures under 750°C. Subsequent crystallization of fluor-richterite seemed to be governed by occurrence of these three phases. More specifically, crystallization of fluor-richterite appeared to start at the interface between two separated glassy phases and/or at the surface of “fluor-talc” crystals.

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The following thermal properties of As-S-Te glasses were determined from the thermal expansion mesurements: Transformation temperatures (T_g), temperatures of initial deformation under load, i.e., softening temperatures (T_s), and average linear thermal expansion coefficients in the ranges from room temperature to T_g (α_l) and from T_g to T_s (α_h). The measurements were made through the entire range of vitrification. The observed values of T_g, T_s and α_l were in the ranges of 28°-182°C, 69°-227°C and (1.75-6.30)×10^-5cm/cm/°C, respectively. The dependence of these properties on composition of As-S-Te glasses was dissimilar to the previously reported results of both As-S and Si-As-Te glasses: The linear relationship was not observed in the present results between the properties and the covalent bond concentration calculated by ignoring the bond species. These results can be explained by an interpretation described in the following paragraphs in consideration of the effect of the bond species formed by tellurium component introduced into As-S parent glasses on intermolecular forces in the glass structure.
When the (S/As) atomic ratio was considerably larger than 1.5, both T_g and T_s increased and α_l decreased with increasing tellurium content up to 10 atom.%, whereas the reverse and/or little changes were observed when the tellurium content was increased further. These behaviors may be connected with the change in intermolecular force due to the formation of partially polar Te-S bonds and the successive formation of non-polar Te-Te bonds in glass.
When the (S/As) ratio was slightly larger than 1.5, the decrease of both T_g and T_s and no appreciable change of α_l were observed with increasing tellurium content up to 10 atom.%. For glasses of the (S/As) ratio less than 1.5, the decrease of both T_g and T_s and the increase of α_l were observed with increasing tellurium content up to 10 atom.%. These behaviors may be attributed to the formation of Te-Te bonds and/or As-Te bonds which leads to the decrease of crosslinkages in the glasses.
The observed values of α_h fluctuated in the range of (4-15)×10^-5cm/cm/°C. The fluctuation may be possibly associated with the elastic after-effect, and the interpretation for the dependence of α_h on composition has not been given for the present glasses.

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Black stones derived from dark green glass were investigated by the method of electron microprobe X-ray analyzer (EMX) and of electron diffraction. It was verified that black stones were composed of copper, sulfur and small amount of nickel from the results of EMX, and their lattice constants were in good agreement with those of Cu₂S from the analysis of electron diffraction pattern. On the basis of experimental results the mechanism of the formation of Cu₂S in the melt is presented as follows. (1) Na₂SO₄ and CuO used as refining and coloring agent respectively are reduced forming Na₂S and Cu₂O at the presence of C under reducing atmosphere. (2) Cu₂S is then produced by the mutual reaction of the two compounds formed.

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