VI CONTENTS OF VOL. XXVII. SIXTH SERIES. 



Dr. Gr. Hevesy on the Diffusion and Valency of the Radio- 



elements 586 



Mr. S. Oba on the Absorption of y Rays 601 



Mr. Harold G. Savidge on the Integration of a Class of 

 Ordinary Linear Differential Equations of the Second 



Order 608 



Mr. R. Hargreaves on Wien's Law 616 



Prof. T. Grodlewski on the Action of Colloids on Radio- 

 active Products in Solution 618 



Prof. K C. C. Baly on Light Absorption and Fluorescence . . 632 

 Mr. A. O. Allen on the Slip-Curves of an Ainsler Planiineter. 643 

 Messrs. W. Morris Jones and J. E. Malaui on the Elec- 

 trical Resistance of Nickel in Magnetic Fields 649 



Dr. I. J. Schwatt on the Sum of an Infinite Series as the 



Solution of a Linear Differential Equation 659 



Mr. W. H. Gibson on the Influence of Volume Change on 



the Eluidity of Mixtures of Miscible Liquids 662 



Mr. J. Eose-Iunes on the Integration of the Differential 



Equation applicable to a Plane Progressive Wave 609 



Prof. A. W. Porter on the Formation of Images by means 



of an Opaque Disk. (Plate IX.) 673 



Mr. C. Gr. Darwin on the Theorv of X-Ray Reflexion. — 



Part II * 675 



Mr. E. Marsden and Dr. P. B. Perkins on the Trans- 

 formations in the Active Deposit of Actinium 690 



Mr. H. Gr. J. Moseley on the High-Frequency Spectra of the 



Elements.— Part II 703 



Mr. Horace H. Poole on the Activity of freshly-formed 



Radium Emanation 714 



Dr. S. A. Shorter on a Classification of Foaming Solutions . . 718 

 Dr. P. B. Perkins : A Determination of the Periods of 



Transformation of Thorium and Actinium Emanation .... 720 

 Mr. W. A. Jenkins on the Effect of a Magnetic Field on 



Metallic Resistance. (Plate X.) 731 



Mr. Grervaise Le Bas on the Theory of Molecular Volumes. — 



Part IL 740 



Notices respecting New Books : — 



James Thomson's Collected Papers in Physics and 



Engineering 752 



Department of Commerce; U.S. Coast and Geodetic 



Survey 752 



Intelligence and Miscellaneous Articles : — 



British Association for the Advancement of Science : 

 Committee for Radiotelegraphic Investigation — 



Special Investigation 753 



On the Recombination of Ions made by a, Rays, by R. D. 



Kleeman 755 



On the Electrons liberated in Ionization, by R. D. 

 Kleeman 755 



