Nickel film deposited in electrolytic solution containing some suitable organic reagent as 1_??_5 naphthaline disulfonic acid show a characteristic structure. Interpretation for the origin of this phenomenon is that the cathodic potential increases by the adsorption of organic agent on the surface and nickel hydroxide is deposited as a result of the rise of pH value in cathodic boundary layer. If it happens so, pH value in bulk solution may affect the structure of deposited film. Observations made on specimens deposited in solution of 1.5_??_5.5 in pH value gave the following results. (a) The surface of film deposited at pH value 1.8 is similar to that deposited in unadulterated solution. (b) The preferred orientation changes suddenly at pH value 3_??_4, below it  orientation appearing and above it  orientation predominating. The former orientation is of the same type as for the film deposited in unadulterated solution. (c) Specimens, deposited at pH values lower than 3, show no “band structure” and no brightness, but films formed at pH values higher than 3 begins gradually to show the “band structure”. (d) Impurity content in each film remains essentially unaltered though there is a tendency of slight increase with the rise of pH value.
An instrument incorporating a phototube and a vacuum tube amplifier for amplification of deflection of commercial galvanometers is described. The most troublesome fluctuation due to the mechanical vibration of the galvanometer coil can be eliminated by mounting the galvanometer and optical system on a simple vibrationless support. By application of voltage feed back, high input resistance of the galvanometer can be attained, and the error due to the voltage drop across the inner resistance of specimens measured becomes negligible. By the analysis of the effect of voltage feed back on the galvanometer circuit it becomes clear that (1) the period of the galvanometer can be shortened, (2) by adding a suitable capacitor to the feed back circuit the critical damping condition of the circuit is fulfilled and (3) the voltage sensitivity limit set by Brownian motion is increased. The voltage sensitivity attained is 7.5×10-9 Volt per division of an output microammeter (300 μA full scale, 100 divisions) while the drift voltage is less than 7×10-9 V/min. The apparatus is now being used satisfactorily for measuring the Hall coefficient of alloys.
Continued from the preceding experiment, the effects of cold-work and low temperature annealing on the rigidity of copper wire are observed by the method of torsion pendulum. Torsion has been used as the means of deformation, and specimens are heated continuously with a constant rate of 1.7°C/min from a room temperature to 400°C. The rigidity is measured at various temperatures within the above range of temperature. Fig. 2 and 3 show the results of the measurement, and Fig. 7 shows the relation between Δt/Tann and the heating temperature. From these measurements and metallographic examinations, the following are found. (1) For all specimens, the rigidity increases gradually at first with the rise of heating temperature. (2) However, it becomes somewhat constant above a temperature θ'1. (3) Above a temperature θ'2 the rigidity begins to increase very rapidly at which the specimens recrystallize.
The growth of interface layer of oxide coated cathodes for about six thousand working hours is studied. The following are expected as the possible physical factors determining the rate of growth of interface layer during the life test. (1) The rate of reaction between barium oxide and reducing agent, mainly silicon. (2) The rate of diffusion of reacting materials (barium oxide or silicon) through the interface layer. (3) The rate of diffusion of silicon out of the base metal. The results of experiment indicate, that the resistance of interface layer increases linearly with the working time, therefore the rate of growth of interface layer is probably dominated by the rate of reaction between barium oxide and silicon. Hence, the interface layer does not seem to affect so much the reducing processes of BaO during at least about six thousand working hours. In addition, the dependence of the growth on the amount of reducing agents contained in base metal and the reduction of interface resistance by the current are studied.
The characteristics of the detecting unit of displacement are closely studied, following the previous report. The minimum value of the resultant valtage, i.e. emin, which is closely connected with the accuracy of control, is reduced almost to zero by means of a simple CR circuit not to interfere with the practical use, and for tele-metering or remote controling use emin iss similarly reduced almost to zero by a simple electronics circuit. Characteristics of these circuits are examined and the feature of this detecting unit is detailed comparing with that of the moving core type deferential transformer which has become of general use for the detection of displacement.