1. Strain and diamagnetic susceptibility. 2. The mobility of positive ions in flames
Banta, Henry Eugene
Wilson, H. A.; Heaps, C. W.
Master of Arts
STRAIN AND DIAMAGNETIC SUSCEPTIBILITY --ABSTRACT-- The magnetic susceptibility of copper and, silver wires has been measured by the Gouy method before and after various annealing processes. Also, the susceptibility has been measured before and after straining specimens beyond the elastic limit, the strains being either twists or stretches. The susceptibilities are found to he increased , by as much as 20 percent for copper and 3 percent for silver by annealing at red heat for 15 minutes in an atmosphere of CO2. This increase is probably due to release of occluded gases or to oxidation or recombination of impurities. Straining the specimens beyond the elastic limit is found to produce no measurable change of susceptibility. Francis Bitter has observed a large effect due to straining these metals beyond the elastic limit. The reason for Bitter's results is not clear, but it is pointed out that no effect is to be expected in copper, at least, because crystals of this metal are isotropic magnetically and have no observable magnetostriction. THE MOBILITY OF POSITIVE IONS IN FLAMES --ABSTRACT-- The mobility was calculated from measured values of the current density, cathode drop of potential, and the thickness of the layer at the cathode in which the potential varies rapidly. The excess of ionization over recombination in the layer was assumed to be proportional to (1—x/x0m, where x is the distance from the cathode, xi the thickness of the layer at the cathode, and m is a constant. J. J. Thomson supposed that in =0, and P. E. Boucher took in = 1. The value calculated for the mobility depends on the value assumed for m. The results give, with m 2 , a value of 1.8; with m = 3, a value of 1.07 cm/sec. per volt/cm for the mobility. It is found that the mobility is the same for salts of Rb, Cs, and K, and that it does not depend on the concentration of the salt. A small increase of mobility with electric intensity is indicated by the results.
Reprinted from THE PHYSICAL REVIEW, Vol. 37, No. 5, pp. 634-637, March 1, 1931