362 



Mr. J. J. Hood on the Rate of 

 S0 2 in Hydrogen. Barometer, 767*8. 



Time, 

 minutes. 



Manometer- 

 reading, 

 millimetres. 

 n. 



Difference of 



pressures. 



n'—n. 



Ratio. 



n"-n f 



n'—n ' 







1 



2 



3 



4 



5 



7 



10 



15 



20 



25 



30 



40 



50 



60 



321 

 354-4 

 378-4 

 388-5 

 394-9 

 399-2 

 407-5 

 415-2 

 4226 

 427 

 429-1 

 430-8 

 432-7 

 433-3 

 433-8 



322-3 



24 



101 

 6-4 

 4-3 

 8-3 

 7-7 

 7'4 

 44 



2-1 



1-7 



1-9 



•6 



•5 



•074 

 •421 

 •633 

 •672 



The foregoing tables show, in comparison with the results 

 obtained for chlorine gas, a rate of absorption at the com- 

 mencement of the experiments in favour of the lighter gas 

 S0 2 , whilst in air both gases are absorbed with much greater 

 rapidity than either C0 2 or SH 2 . 



What seems most remarkable in all the experiments, con- 

 sidering the large size of the absorption-vessel employed and 

 the comparatively small quantity of gas used, is the very great 

 rapidity with which the gases pass into the absorbent. During 

 the first minute about 75 per cent, of the gases SH 2 , CI, and 

 S0 2 are absorbed when the atmosphere is hydrogen ; in an 

 atmosphere of air, too, the amount is remarkably great ; so 

 that the majority of the observations that succeed the first two 

 or three minutes are made when the gases have a compara- 

 tively low tension, in which state there are no very marked 

 differences in their rates of absorption. 



How far the physical and chemical actions that take place 

 at the surface of separation between the gas and the absorbing- 

 agent vitiate the foregoing experiments, as regards the nume- 

 rical results being looked upon as measures of the interdiffusion 

 of the gases experimented with, are points of vital importance; 

 and to elucidate these a number of experiments have been 

 made which as yet do not throw much light upon the matter, 

 but indeed seem to indicate that this method for studying 

 interdiffusion comes nearer the ideal case cited than might at 

 first consideration be expected. In the first place, many ex- 

 periments were performed with a view to see how far the 



