82 Mr. E. P. Perman. [Feb. 4, 



no effect on the result, and I believe it can be safely concluded from 

 these experiments that the density of saturated water vapour under 

 the conditions of the experiment (that is, when mixed with half its 

 volume to forty times its volume of air, at temperatures from 90 to 

 20) is normal. 



Also, it is highly improbable that the density of the saturated 

 vapour alone is more than slightly above normal at these tem- 

 peratures, as the deviations from Dalton's law have been shown to be 

 very small. This is also confirmed by the results of Griffiths (vide 

 supra). 



Summary and Conclusion. 



(1) When air is aspirated through water, it becomes saturated with 

 aqueous vapour with great rapidity. 



(2) In the saturated air so obtained, the pressure of the aqueous 

 vapour is the same as the vapour pressure of water when no other gas 

 is present. 



(3) The density of the aqueous vapour in the mixture is normal. 



(4) The density of saturated aqueous vapour (without admixture) 

 is probably only very slightly (if at all) above normal at temperatures 

 up to 90. 



