78 Mr. Graham's Experimental Researches 



There have left the receiver — of 



Hydrogen gas . . 71.5 out of 75 parts. 



Olefiantgas . . .18.4 75 



The more diffusive gas has, therefore, separated from the other, 

 and left the receiver in greatest proportion. 



Now, when the receiver contains nothing but pure olefiant 

 gas, 72.5 parts of that gas leave the receiver in the circum- 

 stances of the preceding experiment. Hence, when the re- 

 ceiver is half filled with olefiant gas, we would expect the half 

 of 72.5 parts, or 36.25 parts to leave the receiver, and this 

 happens when the complementary 75 parts are common air. 

 But instead of 36.25 parts, only 18.4 olefiant gas leave the 

 receiver in the last experiment. The disparity between the 

 diffusion of each of the mixed gases, in that experiment, is 

 actually greater than the disparity between the solitary diffu- 

 sions of the same gases. 



In the case of mixed gases, the law is— that the more dif- 

 fusive gas leaves the receiver in a greater proportion than in 

 the case of the solitary diffusion of the same gas, and the less 

 diffusive gas in the mixture in a less proportion than in its 

 solitary diffusion — a law of the diffusion of mixed gases, 

 which was confirmed in upwards of forty experiments on di- 

 verse gaseous mixtures. Some of these experiments I shall 

 subjoin. 



(1.) The receiver was charged with 



Carbonic acid . . . ^ 5 \ - 150 

 Hydrogen . . . .75) 



which were allowed to mix intimately over-night. The mix- 

 ture was afterwards allowed to diffuse into the air through 

 the tube for ten hours. Position horizontal, mouth of tube 

 downwards. Thereafter contained, 



Carbonic acid . . . 45 

 Hydrogen . . . . 4.65 

 Air 100.35 



150.00 



In this experiment, a portion of the carbonic acid may have 

 flowed out, for at the end of the experiment the density of the 

 gaseous mixture was greater than that of the atmosphere, 

 while the mouth of the tube opened downwards. 



