the Diffusion of Gases. 



239 



half time under double pressure, as will be evident from the fol- 

 lowing table of observations. Pressure of atmosphere 30 inches. 



The ratio of the times, in hydrogen and air, is not greatly 

 different at different pressures. Thus, the mercurial column was 

 depressed 18 inches, or from 29 to 11 inches. 



By Air, in - 7283 seconds, 

 By Hydrogen, in 3025 seconds, 



7348 

 "3025 



= 2.408 Ratio of hydrogen, 

 1 . = Rate of air. 



It was found that the kind of gas in the receiver made no dif- 



nh 2 



