Volume 7, Issue 6, 01 June 1936
Index of content:
7(1936); http://dx.doi.org/10.1063/1.1745386View Description Hide Description
In order to determine the relative effects of electrode condition, electrolyte and a number of physical parameters on electrolytic capacity, the capacity‐frequency characteristics of a single cell, kept under carefully controlled conditions, were measured for a period of about six months. Some conclusions to be drawn are: (1) While the magnitude of the capacity can be varied over a wide range by change in electrode condition, the general shape of the capacity frequency characteristic is determined mostly by the concentration of the active ion in the electrolyte. (2) The capacity can be decreased greatly by exposing the electrodes to catalytic poisons such as H2S and CO and can be subsequently increased by exposure to either electrolytic oxygen or hydrogen. These effects can be alternated. (3) The capacity is less subject to variations at the higher than the lower frequencies.
7(1936); http://dx.doi.org/10.1063/1.1745387View Description Hide Description
The polarization capacity of a Pt–H2SO4–Pt electrolytic cell of concentration 0.25 N has been studied using alternating currents ranging in frequency from 0.05 to 3500 cycles per second and using aperiodic currents whose time constants range from 0.15 to 1.5 seconds. The empirical law, C=13.6f−m , is found to hold throughout the frequency range with m=0.11. The angle Ψ by which the current fails of quadrature with the polarization is constant within the accuracy of measurement and is in agreement with the Fricke relation, Ψ=πm/2. The capacity as measured by aperiodic currents is found to increase slightly with the time constant. It is shown by a Fourier series expansion that if the alternating current results are correct, the aperiodic decay current is approximately exponential during the early part of the decay and that the measuredpolarization capacity is approximately proportional to the mth power of the time constant. The experimental data are in agreement with this conclusion.
7(1936); http://dx.doi.org/10.1063/1.1745388View Description Hide Description
A rigorous and easily computed formula for the total radiation from an arbitrary current distribution above a plane ``earth'' of arbitrary characteristics is developed. The fields may also be found, though they are not needed to compute the energy radiated. As a by‐product, two new expansions in cylindrical coordinates of i(1)eikr12/r 12, where i(1) is a vector, are found.
7(1936); http://dx.doi.org/10.1063/1.1745389View Description Hide Description
A method is described for measuring the number of atoms of thoriumsputtered from tungsten by positive ions of various velocities in the positive column of an arc discharge. The threshold for mercury ions is 35 volts. The number of atoms sputtered per positive ion in mercury vapor increases with increase in filament temperature and with decrease in arc current. The effectiveness of ions in sputteringthorium from tungsten is in the order neon, argon, mercury.Measurements of emission from a probe permit observations of the rate of loss of barium from an oxide coated cathode. The threshold for sputtering from a cold oxide coated filament by neon ions is approximately 45 volts. The materialsputtered is not electrically charged. There is a difference in nature between the material evaporated and sputtered from an oxide coated cathode. The threshold for sputtering of barium from tungsten is 14 volts for argon ions and approximately the same for neon. The arc current to a coated cathode reduces the rate of loss of coating material under certain conditions.
7(1936); http://dx.doi.org/10.1063/1.1745390View Description Hide Description
A boundary value problem which may be applied to certain cases of heat transfer is worked out. The solution is applied to the investigation of the lags occurring in a medium of finite thermal conductivity enclosed in an infinitely long cylindrical case of infinite thermal conductivity when heat is introduced uniformly into the case, and when heat is evolved uniformly within the medium.
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