IV CONTENTS OF VOL. IV. FIFTH SERIES. 



NUMBEE XXIII.— AUGUST. 



Page 



Mr. M. M. Pattison Muir on Chemical Classification 81 



Mr.W.Bailyon a New Automatic Motion for the Spectroscope. 



(Plate I.j 100 



Mr. J. E. H. Gordon on a Eepetition of Dr. Kerr's Magneto- 

 optic Experiment 104 



Mr. E. S. Brough on a Case of Lightning ; with an Evaluation 

 of the Potential and Quantity of the Discharge in Absolute 



Measure 105 



Mr. S. T. Preston on the Nature of what is commonly termed 



a "Vacuum" " 110 



Profs. "W. E. Ayrton and J. Perry on Ice as an Electrolyte. 



(Plate II.) 114 



Mr. E. H. M. Bosanquet on the Theory of Sound 125 



Prof. J. J. Sylvester on a Generalization of Taylor's Theorem. 136 

 Proceedings of the Eoyal Society : — 



Dr. J. Hopkinson on the Dielectric Properties of A^arious 



Glasses 141 



Mr. J. A. Eleming on the Production of Induced Currents 



in Electrolytes 143 



Prof. J. W. Mallet on the Density of Solid Mercury 145 



Proceedings of the Geological Society : — 



Mr. E. Mallet on the Piling-up of Volcanic Cones 151 



Mr. T. Belt on the Steppes of Southern Eussia 151 



Mr. J. E. Campbell on the Glacial Period 152 



Prof. J. Milne on the Action of Coast-ice on an oscilla- 

 ting area 153 



On the Spectrum of the Electric Spark in a Compressed Gas, 



by A. Cazin 153 



Photometric Eesearches on Coloured Elames, by M. Gouy . . 156 



On a new Metal, Davyum, by Serge Kern 158 



On the Diamagnetism of Condensed Hydrogen, by E. Blondlot. 159 



NUMBEE XXIV.— SEPTEMBER. 



Prof. G. Wiedemann on the Magnetic Behaviour of Chemical 

 Compounds 161 



Mr. "W. M. Hicks on some Effects of Dissociation on the Phy- 

 sical Properties of Gases. (Plate III.) 174 



Mr. C. J. Woodward on an Apparatus to illustrate the Inter- 

 ference of two Plane Waves 184 



Mr. M. M. Pattison Muir on Chemical Classification 187 



Mr. S. T. Preston on some Dynamical Conditions api3licable 

 to Le Sage's Theory of Gravitation 206 



