244 Mr GRAHAM on the Law of 



Correcting for loss of gas by absorption, the final contents 

 would be, 



Air and vapour, 246. 



As the proportion of vapour in the gas at the first, and in the 

 air finally is the same, we may say that carbonic acid is replaced 

 by air in the proportion of 201 to 246. 



201 



0.813 diffusion-volume of carbonic acid. 



Experiment 3. In a third experiment over brine, thermo- 

 meter 62, barometer 29.65, carbonic acid and vapour, . 1 69 

 Replaced by air and vapour, ..... 205 

 Or, allowing for absorption, by air and vapour, . . 206 



- = 0.816 diffusion-volume of carbonic acid. 



But extreme accuracy is quite out of the question in the case 

 of carbonic acid, from the vagueness of the small correction for 

 absorption of the gas by the brine, and from the absorbent action 

 of the plug, which affects, more or less, all the condensible gases. 



The experiment in the case of this gas had been performed 

 repeatedly over water itself, in different diffusion-tubes, and al- 

 ways with an eventual increase to the gaseous contents of the 

 tube of within 2 per cent, of the theoretical quantity, but this 

 mode, and the corrections for absorption, are decidedly inferior in 

 precision to the preceding. 



3. Chlorine. This gas, from its high density, should afford a 

 good illustration of the law, were other circumstances equally 

 favourable, as the specific gravity of chlorine is about 2.5, of 

 which the square-root is 1 .581 1, and the reciprocal of the square- 

 root 0.6325. 100 measures of chlorine should be replaced by 

 158.11 air; or 1 air should replace 0.6325 chlorine, which is its 

 diffusion-volume. 



