CONTENTS OE VOL. XVII. SIXTH SERIES. V 



Page 



Mr. S. Euss on the Diffusion of Actinium and Thorium 



Emanations 412 



Dr. J. P. Y. Madsen on Secondary y Eadiation. (Plate VIII.) 423 

 Notices respecting New Books : — 



Annuaire pour Tan 1909 publie par le Bureau des 

 Longitudes 448 



NUMBEE C— APEIL. 



Messrs. Pollock, Wellisch, and Eanclaud on the Eelighting of 

 the Carbon Arc. (Plates IX. & X.) 449 



Mr. Morris Owen on Erictional Electricity 457 



Mr. W. C. McC. Lewis : An Experimental Investigation of 

 Gibbs's Theory of Surface-Concentration, regarded as the 

 basis of Adsorption. (Second Paper.) 466 



Mr. 0. V. Eaman : Historical Note on the Discovery of the 

 Ultra-microscopic Method 495 



Prof. E. G. Coker on a Laboratory Machine for Applying 

 Bending and Twisting Moments simultaneously. (Plates 

 XI. & XII.) 496 



Mr. E. Hosking on the Viscosity of Water. (Plate XIII.) . 502 



Prof. J. Trowbridge on the Doppler Effect in Positive Eays. 

 (Plate XIV.) . . 520 



Dr. A. Eussell on the Effective Eesistance and Inductance of 

 a Concentric Main, and Methods of Computing the Ber 

 and Bei and Allied Functions 524 



Prof. A. McAulay : Elastic Solid ^ther, with two Moduli, 

 satisfying MacCullagh's Crystalline Optical Conditions . . 553 



Mr. S. A. Shorter on Surface Separatiou from Solutions of 

 Saponin, Peptone, and Albumin 560 



Dr. G. E. Allan on the Magnetism of Basalt 572 



Mr. C. F. Hogley on the Secondary Spectrum of Hydrogen . 581 



Mr. E. F. Burton on the Action of Electrolytes on Copper 

 Colloidal Solutions 583 



The Earl of Berkeley and Dr. C. V. Burton : Contribution 

 to the Osmotic Theory of Solutions 598 



Dr. G-. C. Simpson on the Wilson-Gerdien Theory of Thunder- 

 storm Electricity 619 



Mr. C. T. E. Wilson on Thunderstorm Electricity 634 



Dr. C. V. Burton on the Faraday- Maxwell Mechanical Stress ; 

 and on iEtherial Stress and Momentum in general 641 



Notices respecting New Books : — 



Dr. H. Crew's General Physics 654 



Intelligence and Miscellaneous Articles : — 



New Geological Views on Terrestrial Magnetism and 



Volcanism, by J. J. Taudin Chabot 655 



The Grating Spectrum of the Eadium Emanation, by 

 T. Eoyds 656 



