When corrodability of 18-8 stainless steel to the mother liquor of (NH₄)₂SO₄ is tested by general testing method, the data of corrosion are not always the same in spite of our special attention to its experimental procedure. This arises from passivity of oxides on stainless surface.
In this paper the mechanism of corrosion of 18-8 specimen was discussed, and it is suggested that the testing method by pre-activation of specimen is best for estimating real corrodability of 18-8 material to mother liquor of (NH₄)₂SO₄.

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The shearing stress of a brick is thought to have great influence on the porosity of it, which is very important to brick making. This paper is the description about the newly designed shear testing machine and the test result by it

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The drying rate of vacuum-treated clay bodies and their drying shrinkage were investigated in comparison with those of untreated clay.
The results may be summarized as follows;
(1) The constant rate periods of the drying characteristic curves of clay bodies are lengthened at a small amount by the de-airing treatment.
(2) The drying shrinkage increases slightly with the evacuation.
(3) However, these differences were small enough to necessitate no correction of the drying schedule at factorial operation.

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In order to make clear the relation between rate of corrosion of the artificial graphite electrode used as anode by the electrolysis of sodium chloride solution or potassium chloride solution and physical properties of the electrode, the specific gravity, porosity, water absorption hardness, resistivity and the rate of corrosion by the electrolysis for 14 samples of commercial electrode were determined. From the results obtained it was concluded that the electrode with small electrical resistivity and large specific gravity is most effective for the corrosion resistance.

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This report describes the oxidation-test of artificial graphite, natural graphite, petroleum coke and pitch cope with dry air at 500°C.
We estimated their degrees of graphitization from combustibility (combustion curve).
The results of this test corresponed with the degree of graphitization estimated from physical properties (specific gravity, electrical resistance etc.) and practical test (corrosion by electrolysis of alkali chloride solution).
The Acheson graphite is manufactured from the Great Lake petroleum coke which has high combustibility, but its combustibility is lower than the product from pitch coke which has lower one than the Great Lake coke. Namely, on the combustibility, the relation of the raw material and its product is contrary.

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In quantitative measurement of strain by brittle coating, it is very important for explanation of reliability of this method to investigate the error of measurement. As the previous paper shows, the mean value of distances of cracks which appeared in the coating on the specimen subjected to uniform tensile strain decreases linearly with the increment of strain. However, the cracks do not appear in equidistant, but are scattered in some range. This scattering brings error for quantitative measurement of strain. Then, in measurement of the mean value of crack distances, investigated the relation between the measured number of crack distances and the reliability. As a result of this investigation, we may adopt the various method to elevate the accuracy of the strain determination.

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