512 Scientific Intelligence. 



7. Reflection from Glass at the Polarizing Angle. — Lord 

 Rayleigb concludes a study of this subject with the remark 

 "that even a recently repolished surface, which may exhibit but 

 a small ellipticity, is in a highly complicated condition. Grease 

 itself may be comparatively inoperative optically on account of 

 its index approximating to that of the glass. But why varying 

 degrees of moisture should make so little difference is not appar- 

 ent. Surface phenomena generally offer a wide field for investi- 

 gation, which might lead to results throwing much needed light 

 upon the constitution of matter." — Phil. Mag., Sept., 1908, pp. 

 444-447. j. t. 



8. Emission of Electrons from Glowing Metallic Oxides. — 

 Felix Jentzsch refers to the work of J. J. Thomson and to that 

 of Professor O. W. Richardson on the general subject of the 

 emission of electrons from glowing bodies, and finds that the 

 oxides arrange themselves in respect to rise in potential according 

 to their electromotive series, that electropositive substances hold 

 more free negative electrons than the electronegative. The work 

 which the electron has to do in being thrown off is greater with 

 electropositive substances. This work is performed only at the 

 surface of the substances. The velocities of the electrons was 

 found to be in agreement with Drnde's theory and with the 

 observation of Lenard on the photo effect. The paper of Jentzsch 

 contains a comparison between the energy of electron emission 

 and the radiation energy. — Annalen der Physik, No. 11, 1908, 

 pp. 129-156. j. t. 



9. The Kinetic Energy of the Negative Electrons Emitted by 

 Hot Bodies — J. J. Thomson has stated that the carriers of nega- 

 tive electricity emitted by hot bodies are electrons. Prof. O. W. 

 Richardson has assumed that the transitional energy of the elec- 

 trons inside the metal has the same value as that of the molecules 

 of a gas at the same temperature as that of the metals, and that 

 the translational kinetic energy of the electrons outside the metal 

 possesses the same value. Professor Richardson's paper embodies 

 the result of an investigation of the portion of the kinetic energy 

 which depends upon the component of the velocity normal to the 

 emitting surface. What is determined is the value of \mu~ where 

 m is the mass of an electron and u is its component of velocity 

 perpendicular to the surface from which it is emitted. — Phil. Mag., 

 Sept., 1908, pp. 353-376. J. t. 



II. Geology and Mineralogy. 



1. Die EntvncMung der Kontinente nnd Hirer Lebewelt, ein 

 Beitrag zurVergleichenden Erdgeschichte y by Theodor Arldt. 

 Pages 730, figures 17, and 23 maps. Leipzig, 1907 (Wilhelm 

 Engelmann). — In this large and detailed work the Principal of 

 the Realschule at Radeberg, Saxony, presents the history of con- 

 tinental development and their biota past and present. 



