CONTENTS OF VOL. XXVIII 



(FIFTH SEEIES). 



NUMBEE CLXX.— JULY 1889. 



Mr. J. J. Thomson on the Magnetic Effects produced by Motion 



in the Electric Eield , . 1 



Prof. C. V. Boys on Quartz as an Insulator. (Plate I.) .... 14 

 Messrs. Gary T. Hutchinson and Gilbert Wilkes on a Com- 

 parison of the Mercury Unit with the British Association- 

 Unit of Eesistance 17 



Svante Arrhenius on Electrolytic Dissociation versus Hydration. 30 

 Dr. J. H. Gladstone and Mr. Walter Hibbert on the Molecular 



Weight of Caoutchouc and other Colloid Bodies 38 



Mr. George Puller on a Water-spray Influence-Machine 42 



Prof. Oliver J. Lodge and Dr. J. L. Howard on Electric Eadia- 



tion and its Concentration by Lenses 48 



Notices respecting New Books : — ■ 



Dr. J. Croll's Stellar Evolution and its Eelations to 



Geological Time 66 



Mr. E. A. Eidsdale's Cosmic Evolution 67 



Proceedings of the Geological Society : — 



Dr. C. Callaway on the Production of Secondary Minerals 

 at Shear- zones in the Crystalline Eocks of the Malvern 



Hills.. 67 



Messrs. G. A. J. Cole and A. V. Jennings on the 



Northern Slopes of Cader Idris 69 



Eev. E. Hill on the Eocks of Alderney and the Casquets . . 70 

 The late Mr. A. Champernowne on the Ashprington Vol- 

 canic Series of South Devon 71 



On a possible Geological Origin of Terrestrial Magnetism, by 



Prof. Edward Hull 71 



Notes on Metallic Spectra, by C. C. Hutchins 73 



On the Influence of Solar Eadiation on the Electrical Pheno- 

 mena in the Atmosphere of the Earth, by Sv. Arrhenius . . 75 



