著者らが従来から研究を行っていた特殊スラグセメント (不焼セメント) について, スラグの粉末度をいちぢるしく微粉にして〓焼した硬石膏を添加することによって, 非常に高強度のセメントができることを指摘し, 天然石膏と副産石膏の1種ずつを選び, これらの〓焼温度と試製セメントの物理的性質との関係や石膏の溶解度の変化, 石膏のX線解析等を行い, 加熱による石膏の形態について考察した.
その結果, 粉末度が0.6% (4900目篩残分) のスラグに500-900℃に〓焼した石膏を10% (SO₃として5-6%) と, 刺戟剤として軽焼ドロマイトあるいはポルトランドセメントクリンカーを少量配合して試製したセメントは早強ポルトランドセメントに劣らない高強度のものが得られた. これに使用する原料としてのスラグは, 熔滓の温度が高温でよく水砕されたものであれば, 石灰量は必ずしも45%以上の高塩基性スラグであることを必要としない. また, これに使用する石膏は天然, 副産を問わず600-900℃で完全に〓焼されたβ-CaSO₄であることを要する. 石膏の溶解度は注水瞬間の溶解度が小さく, 徐々に正常の溶解度に近づくものがよく, また, 副産石膏は不純物 (この場合は僅少の螢石等) の影響によって〓焼による硬石膏化が速いので好ましい結果を与えた. 石膏は1100℃以上の高温に〓焼すると分解するが, これをセメントに配合した場合は興味ある結果を得たが, なお研究を要する.
本研究は文部省試験研究費の援助を受けた. ここに感謝の意を表する.

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Continuing their previous studies (This Journal, 58, 300-04 (1950); 59, 18-21, 533-37 (1951); 60, 386-90 (1952); 61, 379-82, 435-40 (1953); 62, 28-33, 618-22 (1954), the authors reported in the present paper the results of their further studies on the reactions on heating hydrated products (calcium aluminate hydrate, xCaO⋅yAl₂O₃⋅zH₂O) of alumina cement. The chief results were summarized as following: (1) Three kinds of samples of alumina cement were taken from three different factories. The ratios of Al₂O₃ to CaO of these samples were 1.7, 1.3 and 1.1 respectively. Two kinds of calcium aluminate, CaO. Al₂O₃ and 3CaO⋅5Al₂O₃, were synthesized as standard samples for the study on the hydraulic binding agents in the hydraulic refractory mortar and concrete. (2) The mechanism of thermal dehydrations of hydration products, xCaO⋅yAl₂O₃⋅zH₂O, in these three samples of alumina cement and two synthesized calcium aluminates above mentioned were studied by the following three methods: (a) differential thermal analysis, (b) thermo-balance and (c) measurement of thermal expansion. (3) Two peaks were observed in dehydration curves on heating the hydrated products; (a) one about 200°C seemed to be due to the hydarted products xCaO⋅yAl₂O₃⋅zH₂O and (b) the other about 300°C to Al₂O₃ xH₂O (or Al(OH)₃). (4) This thermal dehydration drew to the end about 730-780°C, and the largest contraction which amounted about 38% was observed in the hydrated product in the sample of the ratio of 1.7. (5) About 900-950°C, secondary product, xCaO⋅yAl₂O₃, was observed. And then the exothermic reaction was observed at 1000-1010°C with the formation of α-alumina. (6) The dehydrated mass from hydrated alumina cement was not sintered, and they were poor in mechanical strengths. Therefore, some kinds of mineralizer or sintering admixture are necessary to get better strength.

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Visco-elastic properties of thick clay-pastes were studied by torsion method, and found that (1) Viscosity and elasticity of pastes are decreased with increased watercontent, and also diminish elastic property with much water-content, (2) The influence of water-content upon viscosity coefficient is less than elastic coefficient. (3) No relations are found between viscosity, elasticity, and plasticity of ceramic raw materials.

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Titania-opacified enamel frits having the composition varying systematically were subjected to differential thermal analysis. Also X-ray diffraction method was used for the identification of the crystals separted out from glass phase. Two peaks, one the gently sloped and endothermic, and the other sharp exothermic, were observed, respectively at 450-550°C and 550-750°C. The former will very likely be brought out by the stabilization of quenched glass, since the results of dilatometric measurements gave the transformation- and yield points at around the same temperature, while the latter may be attributed to the crystallization of anatase or rutile. Another endothermic effect appearing at higher temperatures will probably be the outcome of the change of the packing of powdered samples occuring at the higher temperature than the yield point. This will, therefore, be of the second importance. The inversion of anatase to rutile occured so slowly that no heat effect was appeared on the thermograms.
With the decreasing amount of titanium oxide the peak became lower and shifted to higher temperature, which might be the result of the reduction of the degree of supersaturation. The same effect was brought out with the decrease of fluorine content, which might be attributed to the increasing grain size of crystallites. The colour change of the normallyfired frit containing various amounts of fluorine seems to justify the authors' inference.
The substitution of boric oxide by phosphoric oxide resulted in the shift of the peak to higher temperature. The curve, however, subjects nothing about the stabilizing effect of titanium oxide.

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