A simple creep testing machine and a thermostat available for 1, 000 hours were designed, which are shown in Figs. 1 and 3. The test piece which is shown in Fig. 2 has the dimension of 4mm diameter and 100mm gauge length. The elongation of the test piece is measured by two dial indicators on both sides of the test piece. The accuracy is in 0·01%, which is worse than when the Marten's mirror apparatus is used, which is measurable 0·001% of elongation, but, for these degrees of accuracy, the construction of the testing machine is simple, and also the thermostat which is able to regulate temperatures within 1% accuracy is easily designed. The experiment was carried out with 0·4% C swedish steel at 480°. The creep diagram is shown in Fig. 4. The creep limit is determined as 8kg/mm² for 1% elongation in duration of 1, 000 hours and 5·3kg/mm² for 0·05%. Fig. 5 shows the results of short time tensile test of the same steel by this creep testing apparatus.

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On the Mechanical Properties and Corrosion Resistance of Mg-Mn-Al Alloys.
Influences of manganese and aluminium on the mechanical properties of Mg-Mn-Al alloys were investigated. Tensile strength, elongation and impact resistance are improved to some extent with addition of manganese up to 2%.
Effects of aluminium on the mechanical properties of these alloys are far more marked than manganese. The tensile strength increases with aluminium up to 6%, The elongation, reduction of arca, impact resistance decrease rapidly as aluminium increases.
The following experiments were made on the heat treatments of these alloys, in which aluminium plays an important role. After quenching and tempering. alloys of these series show a marked increase of hardness when the aluminium content is more than 8%. In the case of alloys, whose aluminium content is less than 6% the increase of hardness due to the heat treatment is not remarkable. In any alloys, the maximum hardness is obtained by tempering at 230.
Corrosion of alloys in water and in NaCl solution was also investigated. Manganese addition above 0.3% makes a remarkable improvement on the corrosion resistance. As to the content of manganese, it was found that 1% Mn in the cast state and 1.5% Mn in the heat-treated condition, show the maximum corrosion resistance. Influence of aluminium on the corrosion resistance in water is different from that in salt solution. In water aluminium has a beneficial effect, while in salt solution, the alloys of 6% Al are more corrodible than others.

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The volume changes of pure aluminium (99.74%), Al-Cu and Al-Si alloys during solidification have been studied by using the KCl+LiCl bath. The main results of the present investigation are as follows:-
(1) The specific volume (specific gravity) of the molten Al at 750-659° agrees with the result obtained by Edwards and Moorman, the volume shrinkages during solidification being 0.0260 cc or 6.21%.
The linear shrinkages from 750° to 21.5° from 750° to 650° (solid) and from 650° (solid) to 21.5° (solid) are respectively 4.32%, 2.58% and 1.85%. The latter value (1.85%) nearly agrees with those obtained by extensometer by the previous investigators.
(2) In the volume shrinkage vs composition curve of the Al-Cu system, alloy of 94.3% Al (max. solidification interval) has the max. shrinkage and then it gradually decreases to 0.0140 cc or 4.44%, at eutectic (Cu 33%) and to 0.0085 cc, or 3.12%, at the composition of CuAl₂ (Cu 54.1%).
In the CuAl₂ side, there is no max. point, because the effects of the solid (CuAl₂) and liquid contractions during solidification are negligibly small compared with the shrinkage of the primary CuAl₂ on solidification.
(3) In the volume shrinkage vs composition curve of the Al-Si system, a max. point of shrinkage exists at 1.7% Si (max. solidification interval) and then it rapidly decreases to 0.0140 cc or 3.39% at 12% Si (Silumin) and to zero at 25.5% Si; the alloys over 25.5% Si, on the contrary, expands during solidification. This rapid effect of decreasing shrinkage by the Si is attributed to the expansion of the Si during solidification which fact has been observed first by the present author.
(4) Among the volume shrinkage of pure aluminium, Al 90 Cu 10%, Al 97% Si 3%, and Al 88% Si 12% (Silumin) alloys, Silumin has the smallest value and also it has the simplest shrinkage curve during solidification.
The specific gravity of pure aluminium decreases by addition of Si in the solid state butincreases in the liquid state.
This phenomenon is attributed, as already stated, to the expansion of Si during solidification.
(5) The expansion of Si during solidification at 577° (the eutectic temp. of the Al-Si system) has been calculated by the mixture rule from the bases of shrinkage of Silumin. From this calculation, the expansion of Si at 577° was found to be 0.066 cc or 13.6% which is quite noticeably larger than the other metals.

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Although there appeared a number of reports on the determination of total sulphur in iron and steel, the most rapid, simple and reliable method is probably the so-called direct combustion-gravimetric method investigated recently by Kar with the extra precautions to prevent the loss of sulphur trioxide produced during the combustion.
In the field of the direct combustion method, however, the titration process seems more recommendable to the steel works' analysis than the gravimetric one, and of all the method based on the titration, the method proposed by Vita can be pointed out as the most interesting one, though it does not seem to be widely adopted as yet. According to the present author's experience, the results obtained by the latter method were usually undesirably high.
In this paper, the present author called the attention of the effect of CO₂ formed during the combustion of samples, on the decomposition of KIO₃+KI mixed reagent and pointed out that the method of Vita should, therefore, be applicable as one of the most accurate methods for the work's analytical purposes provided that the carbon blank is introduced.
Applying the analytical method proposed by the author to the estimation of total sulphur for 17 kinds of iron and steel, the excellent results were obtained.

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The phenomena and prevention of season cracking of a new strong Al-alloy series, which were reported in the previous paper, ⁽¹⁾ have been investigated. The result obtained are summerised as follows:- Season cracking always takes place along the crystal boundaries of alloys, and hence stress alone is not the cause of it. It does not occur in vacuum, but especially does severely in such medium as saturated water vapour or sea water which tends to accelerate intercrystalline corrosion. The closer the yield point and maximum tensile strength of a certain alloy, the weaker becomes its resistance against season cracking. The length of time required to occur season cracking in an alloy varies by degree and direction of working given to that alloy. Its is thus concluded that the season cracking will not occur simply by an internal stress of a metal or a medium that surrounds the metal, but it takes place by the combined action of these two factors.
The season cracking could be greatly minimized even for these alloys susceptible to it by adding special elements to prevent intercrystalline corrosion, coating with some adequated materials, or by special working procedure.

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Among the whole series of binary alloy-systems wh_ich so far have been investigated, there are about thirty cases in which continuous solid solutions are formed. In a survey of all these systems the present writer gives following results.
I. For the formation of continuous solid solution the following factors are to be considered. Firstly, Lattice-Type Factor-as was already suggested by several investigators the two component metals must have the same lattice type. Secondly, Atomic Size Factor which was put forward by Hume-Rothery. Thirdly, Valency and Valency-Electron Factors which were also proposed by Hume-Rothery (including valency electron concentration, electro-negative valency effect and relative valency effect, etc.).
In most cases of the continuous solid solution systems the two component metals generally belong to the same group in the periodic table. This is in accordance with the first and third factors above stated. But, on the other hand, considerable numbers of exceptional cases to this general tendency are known and the writer found that these can be classified as follows. (a) Alloy-systems between I_B group elements (Cu, Ag and Au) and VIIIc-group elements (Ni, Pd and Pt). (b) Systems Fe-V and Fe-Cr. In the systems of (a) class the component metals belong to the neighbouring groups in the periodic table, while in (b) class they are situated in the same period in the table. Therefore, the writer believes that the Periodic Position or Atomic Structure Factor must be introduced as the fourth factor for the formation of continuous solid solution.
II. A minimum point on the liquidus curve in a continuous solid solution system seems to occur nearly at such a composition as to which a law of simple integral ratio can be applied. Formerly Stockdale has put forward that the same rule applies to eutectic mixture in binary system. Both of these facts are justified, because the minimum point in continuous solid solution system can be taken as to correspond to the eutectic point in simple eutectiferous system.

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