CURRENT ToPIcs.
Groups of Electrons in a Sphere of Positive Electricity. A. E. HAAS. (Akad. Wiss. 'd/ien. Ber., cxx, 2a, IIII.)--In Thomson's electronic model of an atom it is a necessary condition of equilibrium that the central attraction on any electron shall be equal to the resultant repulsions of the other electrons and shall also be in the same direction. This condition is not fulfilled in an outer ring of II, and an inner ring of 7 electrons, and one electron at the centre of the sphere of positive electricity. This work is a mathematical search for stable groups fulfilling the condition of equilibrium stated above. The types considered comprise similar and concentric regular polygons, double pyramids, prisms, and concentric regular polyhedra. An interesting result ~is reached concerning the maximum number of electrons capable of forming a ring in equilibrium~ but not necessarily stable. It proves to be 471, as against Thomson's maximum of 5 for stable equilibrium; 471 is just double the atomic weight of uranium. Another result is that when there is equilibrium in a state of rest, and rotation supervenes, the new configuration of equilibrium is geometrically similar, but all the linear dimensions are increased in the same ratio.
Formation and Velocity of Negative Ions in Canal Rays.
J. KOENI6SBERGER and J. KUTSCI-IEWSKI. (Deutsch. Phys. Gesell. Verb., xiv, I, i.)--Many observers are of opinion that the negative