The mechanism of extraction of Ta by TBP in the Ta-hydrofluoric acid-TBP (tributyl phosphate) system is investigated in this report. The results obtained can be summarized as follows: (1) Ta present at a low concentration of HF seemed to be essentially HT_aF₆ at a high concentration of HF, H₂T_aF₇, and at a much higher concentration of HF, H₃T_aF₈ seemed dominant. (2) One molecule of Ta compounds at various concentrations of HF combined with three molecules of TBP organic solvent, and was extracted by TBP in the form of a Ta compound-3 TBP complex. (3) when the polymerization of Ta in the aqueous phase was higher than that in the organic phase, the distribution coefficient of Ta and the percentage extraction of Ta became lower. At a higher concentration of HF the polymerization number of Ta in the aqueous phase was constant and larger than that in the organic phase, independent of the concentration of Ta in the aqueous phase, but at a lower concentration of HF the ratio of the polymerization number in the aqueous phase to that in the organic phase was larger at a higher concentration of Ta, but was smaller at a lower concentration of Ta. (4) The process of Ta-HF-TBP extraction was an exthothermic reaction, and the heat of extraction was 2.41 kcal/mol at 6.36 N HF concentration and 16 g/L Ta concentration. (5) The rate-controlling step in the extraction of Ta in the Ta-HF-TBP extraction system was considered to be the formation reaction of a Ta compound-3TBP complex. (6) In this extraction system, the concentration of Ta in the aqueous phase showed little change by the distance from the interface, but the change in the TBP phase was remarkable. (7) The activation energy for diffusion of Ta species in a 1.28 N HF solution was 3.495 kcal/mol, and that of a Ta compound-3TBP complex in the TBP phase was 5.836 kcal/mol.

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The measurement was made of the flash points, viz., the temperature at which lead and lead alloys suffer heavy corrosion and disintegration in a concentrated sulphuric acid solution. It was observed that the addition of alloying elements within the limit of solubility lowers the flash-point of lead alloys. Their effect may be classified as follows: With the increasing amount of the alloying element, the flash-point of lead alloys is
(1) lowered markedly: e.g. Bi, Sb, Sn, Zn
(2) lowered at first and then increased, but its temperature is lower than the flash-point of pure lead: e.g. Ag.
(3) lowered at first and then increased, resulting in a higher flash-point than that of pure lead: e.g. Ni, Cu, Te.

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Diffusion of Co into a-iron was studied using Co⁶⁰ as a tracter. The diffusion coefficient was determined at temperatures between 800 and 900°C by means of a lathe sectioning method and the α-iron used as a base metal was a coarse grained polycrystalline block (cylinder). The diffusion coefficient obtained is expressed by the equation
D=9.5exp[−(62.3±1.0)×10³⁄RT]cm²sec⁻¹.

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Single crystals of PbSe were heat-treated in selenium vapor in order to control the deviation from the stoichiometric composition. The Hall effect measurement was made over the temperature range from 77°K to 300°K. The carrier concentration was found to be proportional to ±1⁄4 power of the selenium pressure. This fact can be regarded as evidence for the view that the native defect in PbSe is cation or anion vacancy.
Intrinsic carrier concentration n_i can be represented as n_i=10^14.65T^3⁄2exp(−0.115⁄kT).

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The tempering behavior of martensite in an ausformed Fe-27.56% Ni-0.44% C alloy was examined by means of microhardness tests, optical microscopy and transmission electron microscopy. The tempered martensite in the ausformed specimen showed a higher hardness than the non-ausformed throughout the range of tempering temperatures, and maintained a higher hardness level up to higher temperatures than that of the non-ausformed. The tempered martensite in the ausformed specimen was less etched with nital than that in the non-ausformed. The transmission electron micrographs showed that the ausformed martensite had a dense, cloudy distribution of dislocations. The carbide precipitated at the dislocations and also on the twin faults. The precipitated carbides hardly grew at the dislocations but grew on the twin faults. The carbide precipitation and its growth on the twin faults in the ausformed martensite were depressed and delayed during tempering by the presence of dense dislocations.

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The reaction of thorium metal with graphite was studied in the temperature range of 900°C to 1600°C. It was found that the reaction rate was parabolic and the activation energy for the reaction was 53 kcal/mole below 1200°C. Marker experiments showed that the growth of the carbide film was due mainly to the migration of carbon. From these results the rate determining process of the reaction seems to be the diffusion of carbon through the carbide film formed on the metal surface. Hydrocarbons, yielded by hydrolysis of the carbide film, were analysed by the gas-chromatographic method, from which the ratio of ThC/ThC₂ in the carbide film was determined. The film formed below 1200°C was composed of ThC only. However, in the film formed above 1300°C the ratio of ThC/ThC₂ decreased with increasing temperature. These results were confirmed by the X-ray diffraction technique. Parabolic rate constants for ThC and ThC₂ formations and apparent rate constants for the carbide film growth were obtained from the rate constant of the total carbide formation and the ThC/ThC₂ ratio in the carbide. The activation energy for the ThC₂ formation was found to be 120 kcal/mole from the results above 1300°C. The diffusion coefficient of carbon in ThC was calculated from the rate constants for the carbide formation. The amount of thorium carbide which forms in a thorium blanket of a graphite matrix fuel reactor was estimated.

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The reaction of uranium metal with graphite was studied in the temperature range of 800° to 1100°C. It was found that the reaction rate is parabolic and that the activation energy for the reaction is 59 kcal/mole. Marker experiments showed that the growth of the carbide film was due mainly to the migration of carbon. From these results the rate determining process of the reaction seems to be the diffusion of carbon through the carbide film formed on the metal surface. Hydrocarbon, yielded by hydrolysis of the carbide film, was analysed by the gas-chromatographic method. From these results it was confirmed that the film formed in this temperature range was composed of UC only. These results were confirmed by the X-ray diffraction technique. From these parabolic rate constants, the self-diffusion coefficients of carbon in UC were calculated. These values were extrapolated and found to agree well with Chubb’s results by tracer technique.

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Cementitie foils extracted from annealed steels were examined by transmission electron microscopy employing a specimen-tilting device. Sometimes a number of parallel straitions were observed. It was interpreted that they were due to the plane defects: stacking faults or sequence faults on (001), and sequence faults on (010), (100), (011), (103), (021), (111) and (212).

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Equilibrium constants of a fundamental reaction of the aluminium subhalide process, 2Al(l)+AlCl₃(g)=3AlCl(g), were determined by the flow method using argon carrier between 1000°C and 1250°C. As a result of this experiment, equilibrium constants and standard free energy were obtained by the following equation:
logK_p(=P³AlCl⁄PAlCl₃)=−14,440⁄T+9.87
ΔG⁰_T=66,060−45.16T.
The heat of formation and entropy of AlCl(g) obtained from the experimental data and other thermodynamic values were −22,250 cal/mol and 48.7 cal/mol respectively. By the use of the equilibrium constants, the reaction ratio of aluminium trichloride was calculated at a reduced pressure and in argon carrier, respectively.

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In order to study the effect of plastic deformation on the magnetic properties of ferromagnetic materials, the initial permeability and coercive force of nickel single crystals stretched stepwsie up to 50% in shear strain have been measured, by means of the ballistic method at various temperatures ranging from-196°C to 200°C. It has been found that the initial permeability shows a minimum, while the coercive force reveals a maximum near room temperature and this peak moves toward the lower temperature with increasing strain. The application of our theory developed in the preceding paper to these experimental results shows that the dislocation density, N, calculated from the observed values of the coercive force is connected with the shear stress, τ, by the following relations
τ−τ₀∼N in stage I,
τ−τ₀∼N^1⁄2 in stage II and III,
where τ₀, is the critical shear stress. Further, for explaining the change in initial permeability with plastic deformation, the flexibleness of the domain walls is discussed.

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