276 



MR. E. M. WELLISCH ON THE MOBILITIES OP THE 

 TABLE III. 



* Mean value. 



Considering that we are comparing the observed values of the mobility with absolute 

 values calculated from various physical constants of the substances, the agreement is 

 in several cases quite satisfactory ; however, in the case of ammonia and the vapours 

 there is a marked divergence between the calculated and observed values, the former 

 being invariably smaller. The values of the dielectric constants for the vapours 

 appear to be inordinately large, and, in this connection, it is interesting to note that 

 it is also in the case of vapours that there is a marked departure from MAXWELL'S 

 law, K = n 2 , where n is the refractive index. The following table will serve as an 



illustration : 



TABLE IV. 



