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The behavior of anomalous dielectrics
CURRENTTOPICS.
601
H. JORDAN. The 3ehavior of Anomalous Dielectrics. (Deutsch. Pt%ys. Gesell. Verb, xiv, g, 451.)-In this paper the behavior o’f dielectrics with constant and variable applied voltages is fully investigated. The method of von Schweidler is applied to this investigation, the dielectric forming part of a plate condenser. The rate of charge and discharge with respect to time of a practical condenser charged with a steady pressure differs from the theoretical condenser. The divergence is fully investigated, the condensers used being the ordinary telephone type paper-tinfoil condensers. These condensers were found unsuitable for alternating-current measurements, as they behaved exactly like a cable with the distant end open-circuited. This difficulty was obviated by unwinding the condensers and using such a small portion. that it operated as a condenser and the cable effect was no longer The direct-current .measurements were taken by means evident. of a continuously revolving commutator arranged to charge the condensers for a definite fraction of a revolution and to discharge for the rest of’ the cycle, the discharge current being measured at different times of the discharge period by means_ of a ballistic For the alternating current tests a commercial galvanometer. Siemens alternator (w = 2 x +z= 3 14), a small, high-fre_quency and Halske generator (w =, 4,000 to IO,OOO), and for higher frequencies a Poulsen generator, were used. The measurements were The results are plotted in curves, effected by the bridge method. and the original paper should be referred to, as these are not easily abstracted.
Weak Solutions of Radium. H. W. SCHMIDT and H. NICK. (Phys. Zeitsch., xiii, rgg.)-The best methods for making standard measurements of radium by the emanation method are described. It has generally been thought that the emanation evolved from weak radium solutions diminishes with time, owing to a supposed absorption of radium by the glass. The authors find no effect of this kind with hydrochloric acid solutions of pure radium or of radium and barium salts. The currents in absolute e. s. units produced per Curie of emanation in various cylindrical ionization chambers were measured and found in good agreement with the values calculated from the empirical formulae of Duane and Laborde. Mechanical Model of an Electron. U. CISOTTI. (N. Cimelzto, z Ser. vi, 375.)-Beside the rigid electron of Abraham, and the deformable electrons of Lorentz, Bucherer and Langevin, he considers an elastic sphere moving in an infinite liquid and deformed Hence the sphere will by the pressure of the liquid on its surface. become an ellipsoid with its minor axis in the direction of motion. The shortening of the minor axis and the lengthening of the equatorial axis are both proportional to’ the square of the velocity, and so is the increase of volume.
601
H. JORDAN. The 3ehavior of Anomalous Dielectrics. (Deutsch. Pt%ys. Gesell. Verb, xiv, g, 451.)-In this paper the behavior o’f dielectrics with constant and variable applied voltages is fully investigated. The method of von Schweidler is applied to this investigation, the dielectric forming part of a plate condenser. The rate of charge and discharge with respect to time of a practical condenser charged with a steady pressure differs from the theoretical condenser. The divergence is fully investigated, the condensers used being the ordinary telephone type paper-tinfoil condensers. These condensers were found unsuitable for alternating-current measurements, as they behaved exactly like a cable with the distant end open-circuited. This difficulty was obviated by unwinding the condensers and using such a small portion. that it operated as a condenser and the cable effect was no longer The direct-current .measurements were taken by means evident. of a continuously revolving commutator arranged to charge the condensers for a definite fraction of a revolution and to discharge for the rest of’ the cycle, the discharge current being measured at different times of the discharge period by means_ of a ballistic For the alternating current tests a commercial galvanometer. Siemens alternator (w = 2 x +z= 3 14), a small, high-fre_quency and Halske generator (w =, 4,000 to IO,OOO), and for higher frequencies a Poulsen generator, were used. The measurements were The results are plotted in curves, effected by the bridge method. and the original paper should be referred to, as these are not easily abstracted.
Weak Solutions of Radium. H. W. SCHMIDT and H. NICK. (Phys. Zeitsch., xiii, rgg.)-The best methods for making standard measurements of radium by the emanation method are described. It has generally been thought that the emanation evolved from weak radium solutions diminishes with time, owing to a supposed absorption of radium by the glass. The authors find no effect of this kind with hydrochloric acid solutions of pure radium or of radium and barium salts. The currents in absolute e. s. units produced per Curie of emanation in various cylindrical ionization chambers were measured and found in good agreement with the values calculated from the empirical formulae of Duane and Laborde. Mechanical Model of an Electron. U. CISOTTI. (N. Cimelzto, z Ser. vi, 375.)-Beside the rigid electron of Abraham, and the deformable electrons of Lorentz, Bucherer and Langevin, he considers an elastic sphere moving in an infinite liquid and deformed Hence the sphere will by the pressure of the liquid on its surface. become an ellipsoid with its minor axis in the direction of motion. The shortening of the minor axis and the lengthening of the equatorial axis are both proportional to’ the square of the velocity, and so is the increase of volume.