CONTENTS OF VOL. XXXVII. FIFTH SERIES. V 



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NUMBER CCXXVIL— APRIL. 



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Prof. J. J. Thomson on the Electricity of Drops 341 



Mr. S. U. Pickering on the Densities of Solutions of Soda and 



Potash 359 



Eev. O. Fisher on " Densities in the Earth's Crust " 375 



Dr. John Kerr : Experiments on a Fundamental Question 

 in Electro-Optics — Reduction of Relative Retardations to 



Absolute 380 



Mr. E. C. Rimington on the Behaviour of an Air-Core Trans- 

 former when the Frequency is below a certain Critical 



Value. (Plates X. & XI.) 394 



Prof. G. M. Minchin on the Graphic Representation of 



Currents in a Primary and a Secondary Coil 406 



Dr. A. M. Mayer on an Apparatus to show, simultaneously to 

 several hearers, the Blending of the Sensations of Inter- 

 rupted Tones 411 



Notices respecting New Books : — 



Dr. J. H. Povnting's Essay on the Mean Density of the 



Earth ....".., 413 



Proceedings of the Geological Society : — 



Prof. W. C. Brogger on the Basic Eruptive Rocks of Gran 415 

 Mr. E. Rutley on the Sequence of Perlitic and Spherulitic 



Structures (a Rejoinder to Criticism) 416 



Prof. H. J. Johnston-Lavis on Enclosures of Quartz in 

 Lava of Stromboli, &c, and the Changes in Composi- 

 tion produced by them 416 



Rev. W. R. Andrews and Mr. Jukes-Browne on the 



Purbeck Beds of the Yale of Wardour 416 



Mr. H. "W. Monckton on a Picrite and other Associated 



Rocks at Barn too, near Edinburgh 417 



Mr. H. Kynaston on the Stratigraphical, Lithological, 

 and Palaeontological Features of the Gosau Beds of 

 the Gosau District, in the Austrian Salzkammergut . . 418 

 Prof. E. Hull on an Artesian Boring at New Lodge, near 



Windsor Forest, Berks 418 



Mr. D. T. Edwards on Boring on the Booysen Estate, 



Witwatersrand - 419 



Molecular Energy of Gases, by Prof. Oliver J. Lodge 419 



An Experiment to Photograph the Spectrum of Lightning, 



by G. Meyer 420 



On the Magnetization of Soft Iron, by M. P. Joubin 421 



On the Thermal Behaviour of Liquids, by B. Galitzine 423 



On the Thermal Behaviour of Liquids, by P. de Heen 424 



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