自記コンダクション・カロリメーターを試作し, 主としてスラグ系セメントの水和進行速度に関する研究を行なった. 試料としてポルトランド・セメント, スラグ量を異にする高炉セメントおよびアルカリ刺激剤の量を異にする高硫酸塩スラグ・セメントについて石膏類の添加量を変え, これらについてボットル・カロリメーターで最早期水和熱, コンダクション・カロリメーターで初期水和熱, ならびにモルタル強度について測定した.
最早期水和熱は各種セメント中のポルトランド・セメント・クリンカーの量によって定まり, スラグは湿潤熱程度の低い値を示すに過ぎない.
次に初期水和熱について発熱速度のピークの現われる時期と大きさはポルトランド・セメントで10-13時間, 2.1-2.2cal/g・hr, 高炉セメントではスラグ量が増すにつれて低くなり2つにわかれる傾向があり, 時期も遅れる. 石膏は微量の燐酸を含む副産物を用いたために, 添加量が増すに従い凝結と発熱が遅れた. 高炉セメントでは特に良質な石膏を用いる必要が認められた. 高硫酸塩スラグ・セメントでは発熱は18時間附近に1.1-1.2cal/g・hrに達するなだらかなピークとして現われた. この種セメントのアルカリ刺激剤の適量は発熱のピークが一定の形と大きさをとるのに必要な最少量を求めることによって推定出来る. 24時間後の積算水和熱はポルトランド・セメントで35cal/g程度, 高炉セメントで20cal/g程度, 高硫酸塩スラグ・セメントでは14cal/gに過ぎなかった. モルタル強度はポルトランド・セメントにくらべて高炉セメントは特に初期において低いが, スラグ量による差は小さい. 最適SO₃量はポルトランド・セメントで2.8%またはそれ以上, 高炉セメントでは2.1%附近に見出された, 高硫酸塩スラグ・セメントは7日以後はポルトランド・セメントと同等以上の成績を示した.
本研究にあたり文部省化学促進研究費の援助を得たことを記し, 感謝の意を表する.

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The relation between the specific resistance ρ (at 40°C) and V⁴⁺ content of the vanadate glasses of composition, 60 V₂O₅⋅xRO⋅(40-x)P₂O₅; (x=0-25mol%), in which RO represents the oxides of the mono- or bi- valent metal elements, was investigated. It was found that the concentration of V⁴⁺ ion decreased monotonously with the increase of the ratio RO/P₂O₅, and that ρ showed a minimum at V⁴⁺/V_total=10-20% for all R. These facts indicate that the electrical conduction of these glasses may be attributed to the valency exchange btween V⁴⁺ and V⁵⁺. The curves, of ρ v.s. V⁴⁺/V_total do not coincide with each other, which indicates that the decrease of ρ with increasing RO can not be attributed simply to the reduction of V⁴⁺ content, but the characteristic nature of R ion would be playing some important role in the mechanism of conduction. It was found that there is a certain relation between the minimum value ρ_m of resistance and the cationic field strength (c. f. s.) of R ion.
In the region c. f. s.<0.35, ρ_m was increasing with the increase of c. f. s., because R ion, being a network modifier in nature, would have the trend of approaching to the central ion of V⁴⁺-O-V⁵⁺, and the smaller the polarizing power of R ion the smaller disturbance they would made to the valency exchange.
In the region c. f. s.>0.35, ρ_m decreased with the increase of c. f. s., because, in this case, R ion would act as a network former, and R-O bond, having the nature of mixed bond, would not be able to coordinate to the central oxygen of V⁴⁺-O-V⁵⁺.

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The effect of the initial drying of some industrial clay slips on the casting behavior was investigated in connection with the phenomenon of cationic fixation in clay minerals, which has been reported in this journal by one of the authors.
Some industrial slips (Table 1) were dried at the temperatures below 300°C, and again were added with the equal amount of water as before. The rate of increase of the thickness of cast wall was estimated by measuring the change of the head of slip during the casting operation. The drying shrinkage, strength, porosity, and bulk density of the greens were also measured.
It was confirmed that the pretreatment of drying introduces some marked changes in casting properties as well as in the physical properties of greens, although the effects seem too complicated for arriving at some simple conclusions.
The present data, however, suggest that the history with respect to the drying of the mix governs the casting behavior of slips. This is important when scrap is recovered to prepare casting slips. At the same time, the authors pointed out that there is the possibility for improving the casting behavior of some special slips through drying treatment.

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The absorption bands of cerium in trivalent and tetravalent states in silicate and phosphate glasses, whose exact positions are still open to discussion, and the effects introduced by the change of composition and of melting condition were investigated.
For the measurement of the absorption spectra of silicate glasses with poor ultraviolet transmission the thickness of the sample plates was reduced to 0.12-0.02mm by polishing.
The results obtained are as follows: (1) In the silicate glass consisting of K₂O, BaO, and SiO₂, Ce³⁺ gives a sharp and weak absorption band at 320mμ, whereas Ce⁴⁺ gives a broad and strong absorption band in ultraviolet region below 350mμ. (2) In the phosphate glass consisting of K₂O, BaO, Al₂O₃ and P₂O₅, Ce³⁺ gives three sharp and weak absorption bands at 294, 245, and 227mμ, whereas Ce⁴⁺ gives a broad and strong absorption band in ultraviolet region, as before.

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In the previous paper (J. Ceram. Assoc., Japan, 67, 47, 1959), the authors proposed the use of the “heat-standing temperature of artificial mineral wool”, being defined by the temperature, at which the rate of natural linear shrinkage expressed by per cent, per °C reaches to 0.1.
Some marked chapges occur around this temperature. In this paper, some experimental results showing the nature of the change are descrived and also an alternative method of esti- mating the heat-standing temperature is proposed.
Figs. 1, 2 show the shrinkage of various mineral wools during slow heating up to 900°C. The heat-standing temperatures in conformity with the author's definition are listed in Table 1.
Figs. 3-5 show the shrinkage at various holding temperatures for about 6hrs. The curves indicate clearly that the mineral wools continued to shrink gradually when heated above the heat-standing temperature, while almost no change was observed below it.
Figs. 6-10 show the results of compression tests. Samples subjected to the heat treatment below the heat-standing temperature show regular compressibility, giving smooth curves as shown by I, II, and III in Fig. 6. On the other hand, those heat-treated at above the heat standing-temperature gave irregular curves as IV, V, and VI in the same figure.
Tangents of these curves were plotted against compressibility as shown in Fig. 11. As the irregularity is so clearly disclosed in the figure, the authors believe that the compression test combined with heat-treatment is a simple alternative method for estimating the heat-standing temperature.
As shown in Figs. 12-13 quartz glass-wool showed just the same trend.
The irregularity of compressibility seems to be due to the brittleness of the wool, which comes from the devitrification as proved by X-ray analysis, and also by microscopic observation (Figs. 14, 15).

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