IV THE ROYAL SOCIETY OF CANADA 



The Permeability of Balloon Fabrics to Hydrogen and to Helium. 



By R. T. Elworthy and V. F. Murray 37 



A Continuous Flow Apparatus for the Purification of Impure 

 Helium Mixtures. By E. Edwards and R. T. 

 Elworthy 47 



The Production of Helium from the Natural Gases of Canada. 



By J. C. McLennan 53 



Composition of the Vapour and Liquid Phases of the System 

 Methane-Nitrogen. By H. A. McTaggart and E. 

 Edwards : 57 



On the Extreme Ultra-violet Spectra of Magnesium and Selenium. 

 By J. C. McLennan, J. F. T. Young and H. J. C. 

 Ireton 67 



Measurements of Temperature Gradients in Air between Parallel 

 Planes maintained at different Temperatures and their 

 Application to a Determination of the Temperature 

 Variation of Thermal Conductivity. By G. H. 

 Henderson 73 



The Correction Factor of the Canadian Standard Anemometer and 

 ' the Most Probable Maximum Velocity and the Possible 



Extreme Velocity in Gusts. By J. Patterson 81 



Note on a Modified Form of Freezing Point Apparatus. By O. 



Maass 97 



The Velocity of Sound and the Ratio of the Specific Heats for Air. 



By T. C. Hebb 101 



A New Method of Weighing Colloidal Particles. By E. F. 



Burton 103 



On the Partial Condensation of Natural Gas at Liquid Air 

 Temperatures and a Curious Efi'ect Observed with the 

 Nitrogen which Dissolves in the Condensate. By John 

 Satterly 109 



On the Latent Heats of Vaporization of Methane and Ethane. 



By John Satterly and John Patterson 123 



The Study of the Advance of the Ripple in Front of the Surface 



of an Ascending Column of Liquid. By J. C. Thompson 129 



