[asbxjky] thermal CONDUCTIVITIES 77 



of voltage and position for the glow lamp used. The comparatively 

 great conductivity of hydrogen may thus easily be demonstrated. 



Further, the effect of the size of the containing vessel is apparent 

 from the final pair of curves, in which the readings for the two bulbs 

 are brought to the same scale by comparison of the deflections ob- 

 tained at higher pressures. 



Thus, summarising briefly, we may say that the above experi- 

 ments though they do not furnish the absolute values, nevertheless 

 indicate the comparative measures, of the thermal conductivities of 

 the gases used, they demonstrate the existence and nature of the 

 more important factors influencing this conductivity under a diminu- 

 tion in the pressure of the surrounding gas and also show the nature 

 of the growth, under similar circumstances, of the light inten.eity, 

 with total energy expended in a glowing wire. 



Finally, I must here express my thanks to Prof. J. C. McLennan, 

 at whose suggestion the above work was undertaken, for his kindly 

 interest and advice throughout the course of the investigation. 



Physical Laboratory, 



University of Toronto, 

 May 1st, 1913. 



