VI CONTENTS OF VOL. XXI. SIXTH SERIES. 



Page 

 Mr. W. Wilson : The Effect of Temperature on the Ab- 

 sorption Coefficient of Iron for y Bays 532 



Dr. E. D. Kleeinan on the Heat of Mixture of Substances 

 and the Relative Distribution of the Molecules in the 



Mixture 535 



Prof. A. A. Michelson on Metallic Colouring in Birds and 



Insects. (Plate IV.) 554 



Lord Bayleigh on a Physical Interpretation of Schlomilch's 



Theorem in Bessel's Functions 567 



Mr. T. S. Taylor on the Ionization of Different Gases by the 

 Alpha Particles from Polonium and the Relative Amounts 



of Energy required to produce an Ion 571 



Prof. James E. Ives and Mr. S. J. Mauchly on a New Form 



of Earth Inductor 579 



Notices respecting New Books : — 



Messrs. C. R, Mann and Gr. R, Twiss's Physics 583 



Dr. A. E. H. Tutton's Crystalline Structure and 

 Chemical Constitution 584 



NUMBEE CXXV.— MAT. 



Mr. A. M. Tvndall on the Discharge from an Electrified 



Point. (Plate V.) 585 



Prof. Frank Allen on a New Method of Measuring the 



.Luminosity of the Spectrum 604 



Prof. A. Anderson on the Comparison of Two Self-inductions 608 

 Prof. W. A. Douglas Rudge : Notes on the Electrification of 



the Air near the Zambesi Falls - 611 



Mr. C. Y. Raman on Photographs of Vibration Curves 



(Plate VI.) : 615 



Mr. C. V. Raman on the Photometric Measurement of the 



Oblicpiity Factor of Diffraction. (Plate VII.) 618 



Mr. Norman Campbell on Relativity and the Conservation of 



Momentum , 626 



Prof. W. M. Thornton on Thunderbolts 030 



Dr. "William Wilson on the Discharge of Positive Electricity 



from Hot Bodies 634 



Mr. Gr. H. Livens on the Initial Accelerated Motion of a 



Perfectly Conducting Electrified Sphere 640 



Prof. Charles G-. Barkla : Note on the Energy of Scattered 



X-Radiation . . . . , 648 



Miss Ruth Pirret and Mr. Frederick Soddy on the Ratio 



between Uranium and Radium in Minerals 652 



Dr. Charles A. Sadler and Mr. Alfred I. Steven on an 



Apparent Softening of Rontgen Rays in Transmission 



through Matter 659 



