Assuming that in an incorporation of insufficient mixing there exist groups of mean size z, consisting of the mixing ingredient, and that the group is a mixing unit in the incorporation, it has been indicated that the incorporation under consideration can be treated mathematically as a perfect mix. An equation to determine the mean size, z of the groups from a value of variance S² of a imperfect mix has been derived and a degree of mixing, μ has also been defined through z as follows,
μ=1/z=pq/S²R,
where R is a sample size to be taken from the mix, and p and q are mixing ratios of ingredients. Furthermore, another equation to express a relation between variance S² of the mix and mixing time, has also been derived through z, on an assumption that the value of z varies in the mixing procedure, in a way of unimolecular reaction,
S²-σ²=(S₀²-σ²)exp(-ct)
where, σ² is the variance of the perfect mix, S₀² an initial value of S², and C a constant. The above equation has validity to some experimental data concerning mixing procedure of solid particles and morever may be applicable to other kind of mixing procedures such as homogenizing process in glass-melting.

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As the burned dolomite has property to slake into powder when exposed to the atomospheric moisture during storage, several attempts to keep out this defect have been taken in industry and discussed scientifically. Previously, some experiments were reported by the author (at the meeting of Ceramic Association of Japan, October, 1950, abstract page 17; June, 1955, abstract of J. Cer. Ass. Japan, 63 [709] 296 (1955)) and a new opinion on this question was presented that the burned dolomite clinker might be protected against slaking by having their grain surfaces coated with some reaction products which formed at burning temperature between dolomite and its added substances.
This paper deals with an electron-micrographic study to prove the author's view suggested formerly.

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The colouration of silicate glasses by tellurium is obtained by melting in reducing conditions and their colours are various corresponding to the degree of reduction. They are yellowish green, pink, purple pink, and red purple and are shown in the C. I. E. chromaticity diagram. These colouration are deepend by reheating. The purple pink and red purple can be obtatied with the potassium containing glass. Sodium containing glass is only able to become orange pink to pink.
The authors calculate the index of the reducing capacity for various reducing agents and then calculate the ratio of reducing agents to unit weight of tellurium for the reduction of tellurium to alkalitelluride in glass. Using these values the authors investigate the influence of glass composition on the effectiveness of various reducing agents. The necessary amount of reducing agent to produce red colouration is affected by the glass components and must be increased when glass contains such component as calcium oxide, zince oxide, barium oxide, lead oxide, especially boric oxide and arsenic oxide. With the exception of aluminium, many other reducing agents tested, i.e. zinc and tartaric salts, etc., are not effective for the multicomponent glasses.
The authors allude to the result of L. Springer, Sprechsaal, 88, 192-193 (1955), which conclude that the silicate glasses are not coloured red by tellurium. From his data the authors assume that his failure to get red colouration with tellurium is due to the wrong selection of the sort and amount of reducing agent for multi-component glass.
From the practical point of view the authors conclude that it is able to obtain the tellurium pink or red silicate glasses by selecting the glass composition and the reducing agent suitable for the formation of alkali telluride and polytelluride in glass melt.

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American bricks of hard and dense zirconia and insulating zirconia were studied, and also insulating alumina brick were tested. Data for grain size, microscopic observation, X-ray analysis, chemical composition, physical properties, such as thermal expansion, thermal conductivity and corrosion resistance are given. It was confirmed that zirconia has low, thermal conductivity and high resistance against corrosion. Many larger pores were formed in the sample of zirconia brick fired at 1750°C for 1hr in contact with roll scale. It is like bursting expansion of chrome ore.

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Glass fibers of 12 and 22μ in diameter were drawn from the glass melt, the temperature of which were kept at 1170°C during the fiber forming process. The composition of the glass used was as follows: SiO₂ 67, B₂O₃ 12, BaO 2, K₂O 9, Na₂O 9.5, Al₂O₃ 0.5% (in weight).
The glass fibers were repeated at different temperatures between the room temperature and the softening temperature of the glass, and then were etched with hydrofluoric acid. The tensile strength of the reheated fibers was measured before and after the etching.
It was found that, although the tensile strength of fibers decreased by reheating, it regained its original value when its thin surface layer was removed by hydrofluoric acid.

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