Silicate glasses exposed to high-energy radiation develop three visible absorption bands similar to the F- and V-band in alkali halide crystals (R. Yokota, Phys. Rev., 91, 1013 (1953), 95, 1145 (1954), 101, 523 (1956); A. Kats and J. M. Stevels, Philip Res. Report, 11, 103, 115 (1956)). The function of cerium in suppressing formation of these bands were studied spectrophotometrically in glasses of composition 20 R₂O, 10 BaO, 70 SiO₂, and 0.03 to 0.3mol% CeO₂ (R₂O: Li₂O, Na₂O, K₂O).
Glass specimens of about 0.1mm in thickness were irradiated with X-rays of 42kV, 10mA, and changes of their absorption spectra in the range 230 to 800mμ were measured with the Beckman photoelectric spectrophotometer. As the absorption changes were found to be caused not only by color centers but also by other sources such as the valency change of cerium ion, the change due to color centers were separated from the others by heating the irradiated specimen at 150°C for 30 min.; the decrease in absorption intensity by the heating was taken as the absolute change of the absorption due to formation of color centers.
The experimental results showed that trivalent cerium ions suppress development of the three absorption bands equally; i.e., trivalent cerium ions are effective in preventing formation of either of those structural imperfections associated with trapped electrons or positive holes. As to the valency changes of cerium ion itself, a small part of trivalent cerium ions was found to loose their electron upon irradiation by the reaction
Ce³⁺+hν→[Ce³⁺ with positive hole]+e^-.

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This report is extension of previous, i.e. experiments are extended to 2SiO₂-Na₂O, 4SiO₂-Na₂O, SiO₂-Na₂O-CaO, 2SiO₂-Na₂O-CaO, 4SiO₂-Na₂O-CaO, SiO₂-PbO system.
The method of experiment is same as previous. By application of student test and x²-distribution to frequency distribution of diameters of silica, some results are obtained, i.e. extension of reaction, difference of frequency distribution between some systems and population of frequency distribution are became clear.

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Complete hydration products of portland cement compounds and their mixtures with or without gypsum produced by ball mill hydration at 20°C, W/C=80%, were investigated by X-ray diffraction analysis, infra-red absorption spectrum, differential thermal analysis, electron microscopic observation and chemical analysis. The results obtained are summerized as follows:-
(1) Complete hydrate of 3CaO⋅SiO₂ was identified as Afwillite Ca₃(SiO₃OH)₂⋅2H₂O by X-ray diffraction and differential thermal analysis, but calculated composition of this hydrate was C_1.68SH_1.26, based on the chemical composition of initial synthesized 3CaO⋅SiO₂, loss on ignition at 900°C and the quantity of liberated Ca(OH)₂.
The Ca(OH)₂ liberated from 3CaO⋅SiO₂ during the process of hydration was extracted after Lerch-Bogue method until (001) reflection of Ca(OH)₂ was not recognized by X-ray diffraction analysis, so it is considered that both amorphous and crystaline Ca(OH)₂ were measured. The authors supposed that the difference of composition of Afwillite and complete hydrate of 3CaO⋅SiO₂ was not, as Brunauer et al say, caused by missing the amorphous Ca(OH)₂, but the essential property of hydrate having various composition within suitable range. Infra-red absorption spectrum shows the existence of hydrogen bond in Afwillite structure.
X-ray diffraction pattern of complete hydrate of β-2CaO⋅SiO₂ contained diffraction lines of Tobermorite.
(2) The complete hydrate of 3CaO⋅Al₂O₃ was cubic crystal of 3CaO⋅Al₂O₃⋅6H₂O, while that of 4CaO⋅Al₂O₃⋅Fe₂O₃ was the solid solution of 3CaO⋅Al₂O₃⋅6H₂O-3CaO⋅Fe₂O₃⋅6H₂O (lattice constant a=12.614 Å) having approximate composition of 3CaO⋅0.8Al₂O₃⋅0.2Fe₂O₃⋅6H₂O.
Infra-red absorption sprctra of complete hydrate of 3CaO⋅Al₂O₃ and 4CaO⋅Al₂O₃⋅Fe₂O₃ suggest some difference about combined water between cubic calcium aluminate hydrate, solid solution of 3CaO⋅Al₂O₃⋅6H₂O-3CaO⋅Fe₂O₃⋅6H₂O and calcium silicate hydrate.
(3) The complete hydrate of 3CaO⋅SiO₂ with gypsum and 3CaO⋅SiO₂, 3CaO⋅Al₂O₃ mixture with or without gypsum were somewhat different from the complete hydrate of 3CaO⋅SiO₂ (Afwillite).
In the complete hydrate of 3CaO⋅SiO₂ and CaSO₄⋅2H₂O mixture, CaSO₄⋅2H₂O were completely extracted by saturated lime water, while the complete hydrate of 3CaO⋅SiO₂-3CaO⋅Al₂O₃ mixture showed X-ray diffraction patterns and differential thermal analysis curves of 3CaO⋅Al₂O₃⋅6H₂O besides calcium silicate hydrate. So it is not considered that CaSO₄⋅2H₂O and 3CaO⋅Al₂O₃ made solid solution or complex compound with calcium silicate hydrate.
From these results, the authors supposed that the reason of the formation of new calcium silicate hydrate is the difference of the equilibrium of liquid phase produced during the process of hydration.

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