On the basis of previous studies of the glass formation range of borate systems and the relation of composition, refractive index and Abbe's number of borate glass, optical region of lanthanum borate glasses on n_D^-ν diagram and its possible limit of high refractive and low dispersive side were investigated. These lanthanum borate glasses contained oxides of Ti, Zr, Th, Nb, Ta, W, Ba, and Al, and their glass formation range of 4- or 5-component systems were studied. Then the refractive index and Abbe's number of lanthanum borate glasses were measured and from their data and following equations the component factors were calculated.
n_D=1.445+Σia_i+Σib_ix_i²
ν=(n_D-1)/(0.521+Σik_ix_i)n_D
a_i, b_i, k_i and x_i are component factors and molar fraction of M_inO_m.
As a result, it has been proved that caluculated values show good agreement with experimental values. On the basis of this result, then, optical region was researched on n_D^-νdiagram. And the resulted limiting line of high refractive and low dispersive side passes every point of n_D=1.70, ν=55; n_D=1.80, ν=50; n_D=1.90, ν=40 and n_D=2.00, ν=35.

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The change of infrared absorption band, especially in the range of 3740-3660cm^-1, of clay minerals (pyrophyllite, montmorillonite, kaolinite, halloysite, illite and muscovite) by dehydration and rehydration were measured. Clay minerals were rehydrated by keeping in air or in water after the removal of lattice OH at 500°-800°C. The temperatures of dehydration of all rehydrated samples were about 550°C, being 30°-200°C lower than the dehydration temperatures of original clay minerals.
The author discussed about the origin of the drop of dehydration temperatures of rehydrated samples, the bond state of rehydrated water, and the assignment of two separated spectra at 3740-3660cm^-1, as follows:
(1) The absorption band of all specimens due to OH in 3740-3660cm^-1 separated into two spectra by dehydration and rehydration.
(2) The spectra at 3740-3720cm^-1 (2.67-2.69μ) disappeared when the lattice OH was dehydrated by heating at 550°-800°C, but appeared again by hydrothermal treatment (300°C, 85atm., 1-10hrs.). It seems that this absorption comes from lattice OH.
(3) The absorption at 3680-3660cm^-1 (2.72-2.73μ) did not change much by heat treatment up to 700°C. The higher the heating temperature the lower became the intensity of the spectra, but did not disappear easily. The spectra, however, disappear or almost faded away by the treatment which makes the surface area of the crystals to decrease by calcination at the temperatures higher than 800°C. The author posturates that the spectra originate from OH of water bonding directly to the crystal surface or the edges by hydrogen bond.
(4) The water of the rehydration dehydrated at the temperatures lower than dehydration temperature of lattice OH did not entered as lattice OH in octahedral layer, but bonded directly to the crystal surface or the edges by hydrogen bond. However, the water of rehydration can enter as lattice OH in octahedral layer by stronger rehydration method, for example, by the hydrothermal treatment (300°C, 85atms., 1-10hrs.).

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In order to obtain the glasses of the system B₂O₃-CdO-La₂O₃ stable against devitrification, the investigations concerning this phenomenon have been carried out.
According to Frenkel's nucleation theory, the rate of nucleation depends mainly on the degree of supercooling, the diffusion rate of molecules or ions, and the surface tension between the nucleus and the liquid. The authors, therefore, measured the liquidus temperature, the viscosity, and the surface tension of the ternary system B₂O₃-CdO-La₂O₃, using differential thermal analysis to determine the degree of devitrification, and X-ray diffraction to identfy the crystals.
The results obtained are summarized as follows:
(1) The glass-formation range is limited by the immiscibility in B₂O₃ rich region and by the devitrification in oxide rich region, and it was observed that the crystal appeared was different from those outside of the boundary.
(2) The effect of the addition of the components such as SiO₂, GeO₂, As₂O₃, Sb₂O₅, BeO, Al₂O₃, TiO₂, ZrO₂, ThO₂, Ta₂O₅, Nb₂O₅, WO₃, and ZnO on the devitrification was studied. Of these components, the addition of SiO₂, GeO₂, and BeO (<2%) lowered the liquidus temperature and increased the viscosity of the base glass, and Al₂O₃ also lowered the liquidus temperature; they were effective to reduce the devitrification. TiO₂ and ZrO₂, which reduce the devitrification, act in some different way to the same effect, namely, the former by lowering the liquidus temperature, while the latter by increasing the viscosity.
(3) The more stable glass has had lower liquidus temperature and higher viscosity at the same temperature. On the other hand, the viscosity at the lower limit in the devitrification range was never constant. The more stable the glass, the lower was the viscosity at the lower limit. Thus the viscosity range of the more stable glass was narrower than that of the less stable type.
(4) The differential thermal analysis curve of the more stable glass showed a lower exothermic peak which moved towared higher temperature where glass had lower viscosity.
(5) The activation energy of the crystal growth rate was not constant when refered to wide temperature range, it varied from 61.4 to 129kcal/mol. in the range 660° to 820°C, being about a half of the activation energy of viscous flow at the same temperatures. A similar relation was found in CdO⋅B₂O₃ and Li₂O⋅2SiO₂ glasses.

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Glasses containing various amount of trivalent cerium ion (20K₂O, 10BaO, 70SiO₂, 0.1CeO₂, and 0-0.2 Si (mole %)) were first exposed to γ-radiation until they were colored to the same degree, and then, the fading of their color occured with the lapse of time was measured. The content of Ce³⁺ ion in these glasses was also measured by the spectrophotometric method in order to obtain a relation between its content in the glasses and the fading velocity of their γ-ray induced color. The result showed that the higher the content of Ce³⁺ ion in the glass is, the higher the fading velocity of its color is.
On the basis of this result and the results of the spectrophotometric studies on the cerium-containing glasses so far made by the authors (J. Ceram. Assoc. Japan, 68, 132; 169 (1960)), the authors gave their view on the role of Ce³⁺ ion in preventing the γ-ray induced coloration of glass: Being excited by γ-ray irradiation, oxygen ions in glass loose some of their electrons. The Ce³⁺ ions give their weak-bonded 4 f-electrons to the oxygen ions, thus preventing the formation of V-center like defects in glass. At the same time, the Ce³⁺ ions, now holding positive holes as the result of their lending their 4 f-electrons to the oxygens, catch the ionized electrons that would be trapped or were already trapped by oxygen ion vacancies, thus preventing the formation of F-center like defects in glass. The total function of the Ce³⁺ ion in glass under γ-ray irradiation is, therefore, the recombination of the positive holes and the ionized electrons, thus preventing the formation of color centers.

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In order to investigate the influence of alkalies in clinker upon the hydration of alite in portland cement the rate of hydration of 3CaO⋅SiO₂-Na₂O solid solution and of alite was measured by quantitative X-ray diffraction analysis. Also the morphological observation of hydrated products was made using electron microscope and comparing the results with those of setting time and strength.
Furthermore, 3CaO⋅SiO₂ was hydrated in water, and in alkaline solution, and also Jeffery's alite was hydrated in water.
The results are summarized as follows:
(1) The initial velocity of hydration of pure 3CaO⋅SiO₂ in NaOH solution containing equivalent Na₂O to 3CaO⋅SiO₂-Na₂O gave the values intermediate between the cases of pure 3CaO⋅SiO₂ and 3CaO⋅SiO₂-Na₂O solid solution. One of the reasons of these observations may be attributed to the difference of activity in hydration caused by the difference of the crystal structure as well as that of the equilibrium in the initial stage of hydration.
(2) The initial rate of hydration of alite in portland cement clinkers was accelerated with increasing amount of alkalies, and was retarded by the addition of gypsum.
(3) Quick set was observed in the hydration of 3CaO⋅SiO₂-Na₂O without gypsum. As the formation of the solid solution of alite with alkalies in high alkali clinker is highly probable, and usually the quick set is observed in high alkali clinker, it may be concluded that the quick set occures not only by the vigorous hydration of tricalcium aluminate solid solution, but also by the rapid hydration of alite.
(4) The development of the strength of portland cement clinker increased with the addition of gypsum, and decreased with increasing content of alkalies in clinker.
(5) The influence of alkalies was remarkable only in the initial rate of hydration, which indicates that the rate of diffusion of silicate ion through the gel layer is practically unaffected by the existence of Na⁺ and K⁺ in water.
(6) One of the reasons of the inferiority of the strength development in high alkali clinker may be attributed to the decrease of the surface energy by the formation of well crystallized calcium silicate hydrates.

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