CONTENTS OF VOL. L. FOURTH SERIES. Vll 



Page 



Sir J. Cockle on a Differential Criticoid 440 



Dr. J. Kerr on a new Relation between Electricity and Light : 

 Dielectrified Media Biref ringent 446 



Mr. L. Schwendler on the General Theory of Duplex Tele- 

 graphy 458 



Messrs. G. C. Foster and O. J. Lodge on the Flow of Electri- 

 city in a uniform plane conducting-Surface. — Part II 475 



Mr. J. Croll's further Remarks on the " Crucial-Test " Argu- 

 ment 489 



On the Rotatory Polarization of Quartz, by J. L. Soret and 

 Ed. Sarazin 492 



On Thermic Equilibrium and Heat-conduction in Gases ; and 

 on the Integration of Partial Differential Equations of the 

 First Order, by Prof. Ludwig Boltzmann 495 



On Soundng Flames, by M. Decharme 496 



NUMBER CCCXXXIV.— SUPPLEMENT. 



Mr. R. H. M. Bosanquet on the Polarization of the Light of 



the Sky 497 



Mr. W. H. Walenn on Unitation. — Y. Some of the Applica- 

 tions and Developments of the General Formula 521 



Prof. R. Bunsen's Spectral- Analytical Researches. (With 



Three Plates.) 527 



Mr. J. W. L. Glaisher on some Identities derived from Elliptic- 

 Function FormulaB 539 



Mr. W. Weston on the Application of Phosphorus to the 



" Poling " of Copper 542 



Prof. Challis on the Mathematical Principles of Laplace's 



Theory of Tides 544 



Proceedings of the Royal Society : — 



Prof. W. G. Adams on the Forms of Equipotential Curves 



and Surfaces and Lines of Electric Force 548 



Mr. W. C. Roberts on the Liquation, Fusibility, and Den- 

 sity of certain Alloys of Silver and Copper 553 



Mr. T. E. Thorpe on the Specific Volumes of Liquids . . 554 

 Proceedings of the Geological Society : — 



Mr. J. W. Judd on the Structure and Age of Arthur's 



Seat, Edinburgh 556 



Mr. J. C. Ward on the Glaciation of the Southern part of 



the Lake-district 557 



Mr. R. Pennington on the Bone-caves in the neighbour- 

 hood of Castleton, Derbyshire 557 



On the Density of pure Platinum and Iridium and their Alloys, 



by H. Sainte-Claire Deville and H. Debray. . : 558 



Examples of Contemporary Formation of Iron-Pyrites in Ther- 

 mal Springs and in Sea-water, by M. Daubree . , 562 



Index 5Go 



