CONTENTS OF VOL. L. 



(FOURTH SERIES.) 



NUMBER CCCXXVIIL— JULY 1875. 



Page 

 Mr. Robert Mallet on the Temperature attainable by Rock- 

 crushing and its Consequences 1 



Prof. W. G. Adams on a new Polariscope 13 



Dr. E. J. Mills on Nitrated Toluol 17 



Mr. J. C. Glashan on the Motion of a Particle from Rest 



towards an Attracting Centre ; Force oc (Distance) -2 .... 20 

 Mr. H. Bauerman on an Experiment for showing the Electric 



Conductivity of various forms of Carbon 24 



Prof. R. Clausius on the Theorem of the Mean Ergal, and its 



Application to the Molecular Motions of Gases 26 



Captain Abney on Photographic Irradiation 46 



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



Formation of Volcanic Cones 52 



MM. A. Kundt and E. Warburg on Friction and Heat-con- 

 duction in rarefied Gases 53 



Proceedings of the Royal Society : — 



Prof. O. Reynolds on the Refraction of Sound by the At- 

 mosphere '. 62 



On the Action of Magnets on rarefied Gases in Capillary Tubes 



rendered luminous by an Induced Current, by J. Chautard. 77 

 On the Velocity of Magnetization and Demagnetization of Iron, 

 Cast Iron, and Steel, by M. "Deprez 79 



NUMBER CCCXXIX.— AUGUST. 



Dr. W. M. Watts on a New Form of Micrometer for use 

 in Spectroscopic Analysis 81 



Mr. C. Tomlinson on some Phenomena connected with the 

 Boiling of Liquids 85 



Prof. R. Clausius on the Theorem of the Mean Ergal, and its 

 Application to the Molecular Motions of Gases 101 



Mr. W. H. Walenn on Unitation.— IV. The Unitates of 

 Powers and Roots : developments of these, with applications. 117 



Mr. Robert Mallet on the Origin and Mechanism of produc- 

 tion of the Prismatic (or columnar) Structure of Basalt. . . 122 



Prof. J. P. Cooke on two new Varieties of Vermiculites, with 

 a revision of the other members of this Group 135 



