﻿large 

 so the 

 sures. 



New Type of Ion hi the Air. 643 



number, the mobility will be constant only if p 1 =p 2 , 



mobilities are to be entered against the vapour-pres- 



If the plot here is better than in the previous case it 



MOBILITY- RECIPROCAL 

 is to be considered that the fluid is in the state of a dense 

 vapour rather than in that of a liquid. Such a plot is shown 

 in fig. 4. 



An inspection of the figures shows that the fit to a line is, 

 for certain groups of observations at least, better in fig. 4 

 than in fig. 3. The fit might, perhaps, be slightly improved 

 if n were taken equal to a smaller integer for the determi- 

 nations at higher, than for those at lower pressures, which 

 would indicate that the latent heat of the adsorbed fluid 

 becomes greater as its density increases. But the general 

 want of accord amongst these pioneering observations is so 

 considerable that the present line of argument is not con- 

 clusive, and cannot be taken as more than supporting the 

 assumption that the intermediate ion consists of a rigid 

 nucleus surrounded by a dense atmosphere of water-vapour, 

 rather than by water in the liquid state. Further evidence 

 is available, and the assumption is greatly strengthened by a 

 consideration of the circumstances connected with the 

 disappearance of the ion. 



2T2 



