The viscosity of various viscous fluids was determined by the rotating cylinder method of measurement in which the radii, R₁, R₂, of outer and inner cylinders, respectively, the distance, δ, between the bottoms of inner and outer cylinders, the dipped length, l, of the inner cylinder in the fluid, and the speed, t, of rotation of the inner cylinder were changed to some extent, and the following conclusions were derived from the results of the measurements:
(1) For the examination for Newtonian by this method, the selection of the dimensions for l, δ, R₁ and R₂ may be arbitrary.
(2) The value of the end correction, f, is the function of l and δ.
(3) When R₂ is kept constant and R₁ is small, the value of f increases as R₁ decreases.
(4) For the viscosity measurement by the rotating cylinder method, accurate measurement of l is necessary.
(5) The methods of measurement of viscosity used by H. R. Lillie and F. W. Peston is ressonable from the authors' point of view.

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Four series of bodies were fired with the schedules shown in Fig. 1. Soaking was done only on the rapid (180°C/hr) fired bodies. Translucency of the fired bodies were measured by means of photo cell, and the relationships between the translucency and the microstructure of which the details have been reported in the previous papers were discussed with the following results:
(1) Translucency of the bodies increased abruptly within a very narrow range of firing temperatures, and also increased greatly within a short period of soaking.
(2) The temperatures at which translucency of the bodies abruptly increased, lie, e.g., in the case of firing rate of 60°C per hr., at about 1225°C for potash feldspar, and at 1210°C for soda feldspar, and these strictly coincide respectively with the temperatures at which dissolving of the feldspars progress suddenly.
(3) Translucency of the bodies containing soda feldspar increased abruptly at lower temperatures than in the case of the bodies containing potash feldspar while, above these temperatures, translucency of the latter become markedly greater than that of the former. Causes of these inferiority of translucency of the bodies containing soda feldspar are inferred as follows:
a) Soda feldspar usually comprises a solid solution of plagiociase having so large composition range, that its melting is continued up to the comparatively high temperatures.
b) Viscosity of the soda feldspathic melt is lower than that of potash feldspathic one.
c) Owing to these two reasons mentioned above, homogeneity of glasses formed in soda feldspathic bodies is largely inferior to that of potash feldspathic ones.
d) Bubbles contained in soda feldspathic glasses are smaller and more abundant than in the case of potash feldspathic ones.
(4) Addition of coarse grained quartz into feldspathic body, even if a few per cent, will result in a marked decrease of the translucency of the body, if the body will not be soaked at all. With increasing content of fine grained quartz, translucency of the body will also decrease, though not remarkable.
(5) So far as the translucency of the body of the present system is concerned, soaking time is one of the most important factors.
(6) It is confirmed again that the unhomogenity of optical density of glasses formed in the body is one of the most important factors affecting the translucency of the body, as has been reported in the previous gaper.

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Three kinds of undeveloped Rosekis from Hokkaido were studied on their fundamental properties.
Chemical analysis, X-ray analysis, microscopic observation, thermal analysis, thermal expansion and contraction tests were made. Their refractorinesses were determined to be 31⁺, 32⁺ and 35⁺ of the Seger cone respectively.
They seem to be promising resources as refractory materials.

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A sample of brick was removed from a front wall of a 40-ton basic open-hearth furnace after 114 heat services. This brick was divided into four coloured layer zones, and then these zones were separated to chrome-bearing spinet grain and silicate matrix portions by heavy liquid method. Mineralogical constitution of these spinels and matrices were calculated from the results of these chemical analysis. Density, porosity and thermal expansion ratio were determined at each zone. The results obtained are summarized as follows;
On the chrome-bearing spinel grain; (a) Excess (about 6 mol %) of iron oxide is present in the spinel at the hottest zone, whereas excess (2-7 mol %) of magnesia is present in the spinel at the lower temperature zones. (b) Spinel at the hottest zone is rich in magnetite and ferruginous spinel. (c) The amount of MgO⋅Al₂O₃ decreases markedly at the hottest zone to 7 mol % from 45 mol % at the inner zone.
On the silicate matrix; (a) The amount of matrix increases to a maximum at the region behind the hottest working face, and reaches to about 30% of weight of the original brick. (b) It was determined that the matrix at the hottest zone consists of augite. This conclusion is agreed with our previous report by optical test. (c) The matrix at the lower temperature zone consists of forsterite mainly, in which a little fayalite is dissolved. (d) A little (about 3-5 mol %) MgO⋅Al₂O₃ is dissolved in the matrix.

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We, first of all, synthesized simple compounds which probably constitute the BaO-Al₂O₃-SiO₂ clinker reported in the previous study, and measured their heat of solutions and heat of formations together with those of the clinker.
Secondly, we compared these values with those in the system CaO-Al₂O₃-SiO₂, and considered the mineral constitution and the heat of formation of this clinker. Then, it was found that we can study thermochemically the phase equilibrium in the system BaO-Al₂O₃-SiO₂ by means of the solid-state reaction as well as in the system CaO-Al₂O₃-SiO₂.

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