564 Ionic Sizes in relation to the Conductivity of Electrolytes. 



In the two cases hitherto investigated it is found that the ionic 

 volumes calculated from the conductivities on the above hypothesis are 

 in agreement with the " solution volumes " calculated from the 

 densities. This is a striking confirmation of the hypothesis and of the 

 soundness of the method adopted. 



The expression (l+C/i~ s )~ 3 , which is deduced from the conductivi- 

 ties as being proportional to the ionic volume changes of KC1, is applied 

 to a consideration of the density law of KC1. 



Hence, one arrives at a rational density law for KC1, which repre- 

 sents the experimental values of the density from 1 to 6 per cent, 

 accurately to five places of decimals. 



A remarkable difference is manifested in the relation of ionic volume 

 to solution volume as between concentration changes and temperature 

 changes. 



For isothermal concentration changes the ionic volume decreases as 

 the solution volume increases, that is to say, with increasing water 

 combination there is increasing contraction, a result which was to be 

 anticipated. But in the case of temperature changes at constant 

 concentration, there is increasing water combination with diminishing 

 contraction a quite unexpected result. This result is completely 

 explained by reference to the variation in the proportions of trihydrol 

 and dihydrol in the constitution of water with varying temperature. 

 Assuming that the attack of the ions upon the trihydrol and dihydrol 

 is in proportion to their concentrations at the temperatures considered, 

 the volume changes as determined from the conductivities are shown 

 to be in accord with the volume changes as determined by the 

 densities. 



A new variety of viscosity apparatus is described, and a series of 

 measurements of the viscosities and densities of KC1 from to 21 

 per cent, are given. 



