Appendix to Lecture of Jan. 22, 1915 



817 



all gases, having an atomic weight of 4, which is only one-eleventh 

 of the weight of the carbonic acid molecule, whose rate of diffusion 

 is nevertheless eight times that of the lighter helium. Also the 

 relatively slow rate of helium compared to hydrogen is remarkable 

 in view of the diffusion of these gases through quartz, in which case 

 helium has much the srreater rate. 



-60 -50 -40 -30 -20 -10 +!0 +20 -»-30 



Temperatures. 



Fig. is. 



Kelatiox of Temperature to Plate of Gas Diffusiox 

 Through Ixdiarubbee. • • 



Fig. 17 gives the curves, showing the observed variation of 



the rate of gas transference with temperature in the case of six 



typical gases. In Fig. l.s the logarithms of the rates are plotted 



verticallv, instead of the actual rates, with temperature horizontally 



YoL. XXI. (No. 110) 3 H 



