A structure of a dendritic appearance and, usually superposing upon it, a network-or vein-like structure were observed in a microstructure of nickel single crystals, prepared in air by the method of slow solidification. The first structure wasidentified to be really dendrites, since it disappeared completely by being heated to 1000° for several hours in a vacuum. But, the second structure remained unchanged after this heat-treatment, This structure was identified, in view of its appearance under the microscope, to be a veining as already known-with polycrystalline metals including nickel. The most plausible explanation on the origin of the veining seemed to be the precipitation from solid solution of the oxide of the metal during cooling. It was very probable that the above-mentioned single crystals of nickel contained the oxide of nickel, probably NiO, since they were melted and solidified in air. If this oxide precipitated during cooling and formed the veining, it would be reduced and, therefore, the veining would disappear, by heating to high temperatures in a hydrogen atomsphere. In fact, heating at 1000° for 20 days in a hydrogen atmosphere removed the veining almost perfectly. Thus, it may be concluded that the veining observed with nickel single crystals is due to the precipitation of nickel oxide during slow cooling.

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Experiments were made with pure Al, Mg, Cu and with binary alloys of these primary metals respectively; they hardly form solid solution, but, two phases in the, microscopic structure. After annealing these metals and alloys fully, cold rolling of 50% (10% for Mg and its alloys) was given. And heating just for an hour, the recrystallization temperature, the dead softening temperature, and the range between the above mentioned temperatures which is called the softening range, were determined by means of hardness tests and X-ray examinations. From the stand point of the recrystallization temperature, these results were classified statistically into 3 groups as follows:- 1. Of binary alloys, in which the added elements hardly form solid solution at room temperature but form two phases, and whose structure possesses the rough, angular 2nd phase crystals distributing non-uniformly in the matrix, the hardening degree of those subjected-to cold working is remarkable as compared with the primary pure, metal; and when it is heated, it lowers the recrystallization temperature and the dead softening temperature, and the softening range is short. 2. On the contrary, in the case of alloy which possesses the structure of the minute, globular 2nd phase crystals distributing uniformly in the matrix, the hardening degree by cold working is little. When it is heated, the recrystallization temperature and the dead softening temperature of the alloy rises greatly, and the softening range is very wide. 3. Several alloys are situated between the above two.

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The volumes or the specific gravities of solids (crystals) and the remnant liquid, which conjugate during the solidification of alloys, generally change as the temperature descends. The volume difference between the liquid and solid metals in the heterogeneous field is the highly important factor for the common casting, the centrifugal casting, the gravity segregation and the solidification shrinkage curve, etc. The volume changes of liquids and solids during the solidificatoin of several simple eutectic alloy systems (Sn-Bi, Pb-Sb, Pb-Sn, Pb-Cd, Cd-Zn systems) have been calculated from the results of the writer's investigations in past years by means of Honda's thermobalance. The mean results of these investigations are as follows:- (1) The volume change of liquid metals during solidification is much larger than that of solids, and they shrink or expand as the temperature declines; while the latter only shrinks by the coefficent of expansion. (2) The types of the volume change curves of liquids and solids in a simple eutectic alloy system can be divided into five classes. (3) The specific gravities of Sb in Pb-Sb system and of Pb in Pb-Sn system at the eutectic point are respectively 34% lighter and 38% heavier than the remnant liquid metals. We can understand by these results the principle of the gravity segregation in both alloy systems. (4) The volume shrinkage curve during the solidification of alloys can be easily calculated by the specific volume of liquids and solids conjugating at any temperature.

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This study was made on the changes of the Vickers hardness, the electric resistance, the differential dilatation and the thermal analysis in the artificial age-hardening of, , the 24S type super duralumin SD1 (Cu 4%, Mg 1.6%) and SD2 (Cu 3%, Mg 2.5%). The results can be summarized as follows:-
The abnormal changes, observed at the dilatation curve and the thermal change in the ageing at a room temperature, are attributed to the migration of dissolved atoms prior to the precipitation. The abnormal phenomena, which were produced at about 250°C in the course of slow heating, have been assured to be resulted from the precipitation of compound S (or S and CuAl₂). The precipitation of compound S and CuAl₂ could not be separated to observe in this experiment.

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Mit H₂0₂ Lösung wurde uns bisher nur ein zu geringer S -Wert im Vergleich mit normalem Werte gegeben, so studierten wir die Absorbierbarkeit der SO₂ mit H₂O₂ Lösung und fanden, daβ (1) die unvolikommene Absorbierbarkeit der SO₂ auf die negative Katalyse des H₂O₂ Stabilisators in H₂O₂ Lösung zuruckzufÜhren ist, and daβ man (2) durch Beseitigung des Stabilisators mit Vacuumdestillation oder durch Zuschlag des positiven Katalysators die gesamte SO₂ absorbieren kann, wobei CuCl₂ als positiver Katalysator geeignetst ist.
Nach diesem Versuche untersuchten wir den Mechanismus der SO₂ Absorption in H₂O₂ Lösung, die abnormale Katalyse der Cu SO₄ Lösung and die, , “Stumpfe” SO₂.

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