Scientific Serials

Abstract

Annalen der Physik tend Chemie, xxix., No. 11.—B. Dessau, on metal films arising from the disruption of a kathode. Discusses the production of mirror-like films such as obtained by Plücker, Crookes, and Wright from the disgregation of the metal kathode in Geissler-tubes. With a pointed kathode and a flat glass surface as recipient, the film forms a flat conical deposit, showing interference-rings in reflected light, and proving also the presence of optical dispersive power in the metal. The dispersion in films of platinum, iron, nickel, and silver. It is anomalous in the case of gold and copper. The films are double-refracting, and, in the case of oxidisable metals, disappear on oxidation.—Ed. Hagenbach, propagation of electricity in telegraph-wires. Experiments made with chronographic apparatus on Swiss lines, together with a discussion of the results of Wheatstone, Walker, Guillemin, and others. Arguing from theory, the author compares, not the apparent speed, but the ratio of the time to the square of the length of circuit.—B. von Kolenko, reply concerning the pyro-electricity of quartz. Maintains, against Prof. Hankel, that the poles of a warmed quartz crystal are not altered during cooling by passing through a flame.—E. Edlund, remarks on H. Hoppe's communication on the theory of unipolar induction.—S. von Wroblewski, on the representation of the rotation between the gaseous and liquid states of matter by isopyknal lines. The transition of state is represented by curves drawn on a diagram having, for given definite densities, pressures as ordinates and temperatures as abscissae; such curves being termed isopykns or isopyknal lines. The result of examination of these curves shows that, though there is no such thing as an absolutely definite critical temperature or critical pressure per se, there is a critical density for every liquid.—K. Schmidt, on reflection at the surface of crystalline elliptically-polarising media. Experiments made with a crystal of cinnabar, and results compared with the formulæ of Voigt and that of Ketteler. The latter leads to closer correspondence than the former with the facts of observation.—H. Muraoka, on the deformation of metal plates by grinding. The radius of the curvature produced by grinding metal disks set in a bed of fusible alloy is proportional to the cube of their, thickness—K. Exner, validity of lens formulæ for non-homogeneous lenses.—E. Budde, a means of deciding between the electro-dynamic point-laws of Weber, Riemann, and Clausius. This gives the elementary theory of an experiment not yet made.—J. Kollert, on a new galvanometer. This is practically identical with Gray's form.