Analytical study on frictional torque at pivots and bearings has been pursued by many workers but very few treated the problem of internal stress induced at the extremities of pivots. In the present work, pivots used in switch board indicating instruments are taken up and the stress problem is dealt with theoretically with photoelastical experimental verification. In addition, most desirable hardness and stiffness that pivots should have after quenching are theoretically derived. Electron-microscopical observation reveals metallurgically the state of pivots now in universal use as far from ideal. Technique of producing pivots is touched upon and the use of electric discharge is mentioned as the best means of quenching.
A piece of nickel plate on which surface ammonia gas was adsorbed is bombarded by slow electrons and the process of gas evolution is studied by analysis, the principle of the method of which is based upon Knudsen's equation expressing that the flow of low pressure gas through a narrow tube is inversely proportional to the square root of molecular weight of the gas. The adsorbed gas being ammonia, exact analysis becomes possible because of condensation of ammonia at liquid air temperature. By this condensation, proportion of hydrogen, if any, in the evolved gas can be made known by pressure measurements. Three different processes of gas evolution were observed, (1) When the electron energy is below 6 volts, ammonia evolves undecomposed. (2) At 6 volts, decomposition of ammonia suddenly begins-probably by bimolecular reaction-and hydrogen evolves. The evolution has its peak at 12 volts. (3) From about 16 volts, another kind of decomposition-by monomolecular reaction-begins, the product increasing monotonously as the energy of electrons is raised. Next, the case of adsorption of water vapour was examined. The spoiling action of water vapour on cathode reduced the electron current, hence the amount of evolved gas, very much, rendering the measurement almost impracticable. A device was made to cope with this case by the use of two cathodes, oxide cathode and pure tungsten cathode. When decomposed, water vapour gives measurable permanent gases; this made the determination of the amount of evolved water vapour possible by observing the difference in amounts of decomposed products on the two cathodes. The obtained results itemized below are more or less the same as in the case of ammonia. (1) When the adsorbed amount is large, water vapour evolves undecomposed at low voltages of approximately 3 volts. (2) At 7 volts, water vapour decomposes suddenly by bimolecular reaction and hydrogen evolves. The evolution has its peak at 12 volts. (3) From 16 volts, the decomposition is by a different process, the monomolecular reaction, the product increasing remarkably with the rise of voltage.
Energy state of adsorbed hydrogen on metal surface was discussed by Kobosew and Anockin referring to data on the evolution of hydrogen from the surface by bombardment of electrons of a certain energy. The author through his experience wondered if this evolution had some connection with the presence of watervapour and carried out the following experiments to ascertain it. A piece ofout-gassed nickel plate was prepared and subjected to bombardment by electrons of various energies. Evolution of gas from the plate was measured in three different states of the plate: Case 1, the plate was exposed to hydrogen which was thoroughly dried by being passed through a liquid air trap; Base 2, ditto, except the drying of hydrogen being merely with sulphuric acid; Case 3, no pre-treatment. In Case 1 and Case 3, results were almost the same, but in Case 2, a great deal of gas evolved by about 7 volt electrons. Even this alone shows that, when hydrogen is made to adsorbe in the presence of water vapour, the effect of water vapour can not be ignored. For further ascertainment, the plate was divided into two halves. One of them was pre-trea-ted by being used as cathode in electrolysis in dilute sulphuric acid, the other by merely being left in the acid duringthe electrolysis. No difference in gas evoluthion was found between the two. Next, the two were degassed, their positions reversed, and bombarded, but the result remained the same. The one that was merely left in the acid was now wetted with distilled water; the result was still the same. But, when one was wetted with water and the other was not, the gas evolu-tion from the former was definitely larger than from the latter, this difference becoming smaller in time, eventuallyalmost disappearing. The above testifies that the hydrogen that was made to adsorbe played no part in the evolution of gas. No doubt, some gas does evolve by bombardment, but this is either water vapour or its decomposed product.
In germanium p-n junctions prepared by alloying indium into n-type base, electrical characteris-tics and structures of defects involved in the periphery of indium dot are discussed. From the viewpoints of both electrical characteristics and structures these defects are conviniently divided into following two types. One type of defects is found at the outermost periphery of the junction; it consists of (i) lattice defects in the immediate neighbourhood of p-n boundary, (ii) m-n junctions and (iii) micro-unevenness of p-n boundary. Electrically these are characterized by a large back-ward saturation current as well as lowand distributed values of breakdown voltage which leads to a nearly linear voltage-current relationship and to a soft breakdown haracteristics even at low temperature. The other type of the defects is found at somewhat inner part of the periphery and consists of (i) m-n junctions and (ii) lattice defects involved in the p-n boundaries near those m-n junctions. Electrically, breakdown voltage is lowerd at those regions. By an ordinary electrolytic etching, the defective structures of the former type can be easily removed while those of the latter can be hardly removed. In the samples which are perfectly free from defects of the latter type very sharp breakdown characteristic is observed. This indicates the fact that in ordinary alloyed germanium p-n junctions, breakdown characteristic is spoiled by the inclusion of these defective structures. In this work, the above conclusion in obtained from the measurements of electrical characteristics of samples, prepared through various temperature schedules of alloying process and various stages of electrolytic etching under room and liquid nitrogen temperatures. In locating the defective structures on junction surface, copper plating method is also applied as mentioned in the preceeding paper.
The object of this work is to find the relation between sharpness ofphotographic image and the shape of characteristic curve of photographic materials, and to examine quality of tone repro-duction of the curve. Cinema positive film and edge image formed by it are used as the subject of this investigation. The straight line portion of characteristic curve of positive film is expressed by equation of the first degree, and its toe portion by equation of the third degree. The exposure distribution of edge is transferred through a photographicoptical system to the positive film. The line spread function of the photographic optical system can be considered to be a Gauss' normal distribution function because the system is composed of several low pass filters of the same order suchas photographic lens, negative film, printing optical system, and so on. Sharpness of image of the edge formed by the positive film, which has various shapes ofcharac-teristic curve, is calculated by the method of numerical integral. In this paper, acutance is accepted as the measure of sharpness. Equi-acutance lines drawn on the plane of gamma versus length of the toe is shown in figures. From these results, it may be concluded that, as gamma of charac-teristic curve is increased, the sharpness of edge image is improved, and as the length of the toe of the curve is decreased, the said sharpness is improved in the same way. Although the characteristic curve with high gamma and short toe gives excellent sharpness for edge image, it gives poor quality of tone reproduction for highlight region. The relation between the shape of characteristic curve and tone reproduction of highlight region is obtained by calculation and is given in figure. Thirty-two characteristic curves of commercial positive film are analysed, and the value of gamma and length of the toe are obtained. These data are also plotted in figures.
The precipitation process of Mn from super-saturated solid solution of Al-rich AI-Mn alloys is studied with the following results. (1) From experimental results obtained by X-ray method and electric resistance measurements, it is concluded that in Al-Mn alloys, the Guinier-Preston zones are not formed in the process of precipitation. (2) Metastable phase G appears at the early stage of precipitation but it vanishes with the advance of annealing and all theprecipitates become MnAl6. Electron microscope revealed the. transition of stateof the precipitate from G-phase to MnAl6 which leads to another conclusion that G-phase is a metastable intermediate state the precipitate assumes before it turns into MnAl6. (3) Impurities such as Fe and Si accelerate considerably the precipitation process.