For the purpose of finding out the relations between the types of abrasion, i.e. frictional and impact abrasion and some physical properties of alumina silica brick the experiments have been made by rolling test in ball mill and sand blast test. It was confirmed, that (1) the resistance to frictional abrasion increases in proportion to the decrease of apparent porosity, and (2) the resistance to impact abrasion is affected by Shore's hardness and the porosity of the refractory.

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The structure and its change by reheating of the mass obtained by melting the batch prepared by adding titania to dunite in an electric arc furnace under reducing condition were investigated. Also the properties under load at high temperatures were observed.
Titania was confirmed to enter into the reaction with iron oxide and magnesia of dunite forming, in the first place, the compounds, (Mg, Fe) O⋅TiO_2-n, and then, with the increasing amount, remain as brookite or as the lower oxides of titanium. Coexisting with forsterite these compounds gave a dense and compact ingots, although they partly volatirized and mingled in the substances scattered during the electromelting.
The thermal analysis showed the distinguished peaks at 500°-600° and at around 800°C. Furthermore, a profound weight increase was confirmed between 400° and 800°C.
The properties under load at high temperatures were good in reducing atmosphere, but the reheating in air lowered the quality owing to the formation of low melting substances in the structure of ingot.

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β-C₂S may be obtained by water quenching from the temperatures higher than the α_??_α′ transformation. In this case, however, the batch should contain the impurities which stabilize the modifications of higher temperatures, β or even α, α′, by the substitution within crystal lattices.
This paper concerns with the X-ray investigation of the stabilizing action of various amount of different impurities. Moreover, the authors discussed the stabilizing action from the results of the measurement of the change of the transformation temperatures of α′, β and γ.
Cr, V, P, and B showed the marked effect especially for stabilizing β, so that it was possible to obtain β even by very slow cooling. Furthermore, the increasing substitution of Cr, V, and P for Si produced α, while that of B stabilized α′ form.
Al, Fe, used alone were not powerful. They stablized β by water quenching from high temperature, but they were not able to produce α and α′ crystal.
Ti, Mn have practically no power, and even the water quenched samples were contaminated by γ modification.
From the results of the investigations of the series of batches containing comparatively large amount of substituting elements the authors concluded that Cr substitutes for Si⁴⁺ as the pentavalent ion. This result was compared with the action of other pentavalent ions, V, P and also with E. F. Osborn's work which showed that author's conclusion is reliable. Cr stabilizes α, β forms by the same action with V and P.
The ionic radii of the stabilizing elements produce an effect on the expansion and contraction of the b-axis of β-C₂S. Al³⁺, Fe³⁺, whose ionic radii are fairly larger than Si⁴⁺ are able to stabilize only β-C₂S. Cr⁵⁺, V⁵⁺, P⁵⁺, the ions of nearly the same size as Si⁴⁺, may easily-substitute Si⁴⁺ and stabilize the α crystal of hexagonal symmetry from the monoclinic β form.
B³⁺, an ion smaller than Si⁴⁺, stabilize α′ with the change of axial angle. Taking into consideration of the fact that Ba²⁺, a larger ion than Ca²⁺, can also stabilize α′, the author came in the same conclusion as that of the theory of stabilization advanced by A. Dietzel. We have discussed also the change of the size of lattices of α, α′ and γ brought about by substitution.
Transformation temperatures of the modifications were measured by thermal analysis with a result that the transformation temperatures of β→α′ and α′→β were lowered in proportion to the amount of substituting agents. It was observed that the stabilization at high temperature was influenced by the nature and amount of impurities.

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It is said that under the equilibrium condition, potash feldspar decomposes into leucite and melt at about 1150°C, which is within the temperature range for the firing of porcelain. Therefore, it is an important problem to know whether the leucite is actually formed in porcelain bodies containing potash feldspar during the firing process.
Potash feldspar specimens fired at 1150°-1450°C, or soaked at 1260°C for 4hrs and kept at 1300°C for 10.5hrs, were examined by means of polarization microscope and X-ray diffraction (Fig. 1.), but with a result that no leucite was detected in the fired specimens. Furthermore, specimens consisting of potash feldspar and quartz and -or kaolin were examined by the same way without being able detect in their fired specimens either.
From the results obtained it was concluded that the potach feldspar does not decompose leucite and melt, but melts completely into glass, so far as it is fired with the schedule used in the porcelain bodies.
The fact can be explained as follows: If the potash feldspar begins to melt at higher temperature than T₂ (Fig. 3A), it does not decompose into leucite and melt which are coexsting in the most stable condition, but usually melts into a glass, the only one which is the next stable. These relations between the phases formed with temperature and time are infered as Fig. 3B.
The compositions of porcelain bodies containing potash feldspar are usually in the shadowing range of K₂O-Al₂O₃-SiO₂ diagram (Fig. 4.). From the diagram it is apparent that the leucite is formed only in the very high potash feldspar bodies which are higher in K₂O than that of N-Z line in Fig. 4. Therefore, in the porcelain bodies, leucite is hardly formed even if they are fired under the equilibrium conditions.

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A model of a bridge-wall tank was made from plastics to the scale 1/50. Molten glass was replaced by 82% glycerin and its flow in the model under conditions satisfying as fare as possible the law of similitude was studied by the following method. Grains of plastics covered with aluminium powder, whose specific gravity was made as nearly as possible the same as that of glycerin, were introduced as tracer. Illumination with a thin sheet of light across the tank made the motion of the tracer particles visible, and the velocity distribution in the flowing glycerin was estimated from photographic records of the tracks. The temperature distribution in the fluid was measured by Cu-constantan thermocouples. The effect of changes of heat input from the top surface and the arrangement of heaters on the flow patterns and the temperature distribution was investigated.

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The strength of the conical plates of 160mm in base diameter and 65mm thick made of the optical glass BK-7, which will be used for the porthole of bathyscaphe “Kuroshio”, was measured. Also some experiments were carried out using the plates of 15, 20 and 30mm thick in order to calculate the lower tolerance limit of 65mm plate.
The observation of the process of rupture under the pressure increase with constant rate has revealed that the pressure of starting the leak (W) was, in general, by far higher than the strength (S), of starting the rupture, so that the relation
W/S≥3
will be estalished.
The authors concluded, therefore, that the safty of the conical porthole glass has been proved.

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