The calcined gypsum from sea waster can be utilized for ceramic moulds, in the case where complete washing of raw material and its careful calcination are taken into account. Sodium sulfate leaving unwashed has been found to be desperate for this purpose.

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The authors have analized chemically, and accomplished microscopic cxamination of two kinds of glaze of most old earthenwares which were discovered from the ruins of old earthenware-furnace at Seto district, it is concluded that old Seto-earthenwares were ignited with very high temperature, and glazes are strong against water or chemical corrosion, also it is certain that as a component of glaze the ash of camellia was used.

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Three kinds of glaze of Seto-earthenware Ofukeyaki, Shinoyaki, and Tetsuguro, and two kinds of plant ash which were used as a component of above glaze, were all examined by ordinary chemical analysis.
It is concluded that every glaze has its own special character.

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In the course of the fundamental studies on dolomite refractory, the composition range which have molar ratio of CaO/MgO=1.0, 0.75, and 0.5 was studied in this report.
Anti-slaking property were determined by water immersion method at 175°C for 8 hours and were measured by the weight percents of the particles remained on the 6 mesh Tyler's sieve.
Test pieces which were made from dolomite, magnesite clinker, pyrite cinder and qualzite, and had molar ratio of CaO/(Fe₂O₃+Al₂O₃+SiO₂)=1-3, SiO₂/(Fe₂O₃+Al₂O₃)=1-13, were burned at 1440°C and 1500°C for 1 hour.
Dusting, surface luster, crack, and linear shrinkage after these firing were listed in Table 1-3 and shown in Fig. 1. Slaking proerty was listed in Table 4 and Shown in Fig. 2. Refractoriness was shown in Fig. 3. Dusting field and contours of melting point in the special range with respect to corrosion, were measured and shown in Fig. 4.
The results of this study showed that the refractories which have the quite good refractoriness of S. K. 37 and stability against the slaking could be obtained in the narrow range on the diagram of molar ratio of CaO/(Fe₂O₃+Al₂O₃+SiO₂) and SiO₂/(Fe₂O₃+Al₂O₃). (Cf. This Journal 1950, 58, 46, and 195.)

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The authors, in continuing the previous studies on the relation between chemical compositions and water solubilities of glasses, reported the results of further studies on the water solubility or water resisting degree of prepared test glasses containing titanium dioxide TiO₂ in amounts of 2, 4, 6 or 8% by replacing the same amount of lime, silica or both of them in the standard soda lime-silica glass (Na₂O: 15%, CaO: 13%, and SiO₂: 72%). The tests were carried out by the powder method with variuos heating conditions in water, as following: (1) under the atmospheric pressure on water bath, and (2) under the hydrothermal pressure of superheated steam in the closed autoclave by the following four cases, (a) 8 atm. and about at 172°C, (b) 17 atm. and about at 205°C, (c) 25 atm. and about at 225°C, and 40 atm. and about at 251°C. The results of these experiments, (1) cc of titrated N/50-H₂SO₄ solution, (2) the percentage (A) of dissolved sodium oxide Na₂O by the calculation, (3) the percentage of weight decrease (WD) of dissolved Na₂O and SiO₂, and (4) the percentage of (A)/(WD) of the dissolved Na₂O (A) to the weight decrease (WD) were obtained and fully discussed. Thesse result were compared with those reported in the previons report IX. (Department of Applied Chemistry, First Faculty of Engineering, University of Tokyo) (Feb. 18, 1951)

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The glass to metal seal is a problem of practical importance, concerning which many investigations have been reported. In the previous paper, we studied the stresses which come from the differerence of expansion between glass and metal, as to the case of soft glass to Dumet seal.
In this paper, the auther further proceeded to the cylindrical seals with tungsten, molybdenum and fernico inside, each of which shows equal expansion in radial and axial directions, showing that no particular considerations are necessary in the stress calculations of Hull and Burger as in the case of dumet seal.
The outcome of photo-elastic experiments indicates that tungsten sealed in borosilicate glass introduces tensile stresses in tangential and axial directions while molybdenum and fernico result in tension in radial direction.
When the photo-elastic pattern proved to be tonsile as in the former, it is necessary to raise the ratio of diameter (glass vs. metal b/a) or to cool with as slow rate as possible after sealing lest tangential and axial cracks should happen:
On the other hand when it is compression, the reduction of b/a or the moderate rapid cooling is rather desirable for the prevention of oxide film from being broken by radial tension.
We determined experimentally the moderate rate of cooling as well as the breaking stress of oxide film in the fatter case.
It is of great interest to pressume the stress relaxation by viscus flow of glass during annealing, as to which some experiments were carried out in the tungsten seal.
Several fernico alloys were tested as the adequate metals sealed in soft glass, and the results suggested that Fe 47, Ni 30, Co 23 alloy could be used with success as the sealing metal in the button stem of receiving tubes in the place of dumet which has been fairely difficult to be sealed when the diameter is larger than 1mm.

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