56 



THE ROYAL SOCIETY OF CANADA 



from the numbers ^iven in Table VII are much smaller than one 

 should expect them to be if the inverse pressure law held up to as 

 hifih :v.s 116 atmospheres. 



Kovarik has shewn that this law applies in the case of air up 

 to 75 atmospheres, and for positive ions up to this limit he finds pkj 

 = 1'346 and for the negative pkg = 1-89. The mobility for the 

 positive ion deduced from these experiments is there only about 

 l/22th and that of the negative ion l/26th of what one should expect 



Figure 9 



to get if the inverse pressure law held between 75 and 116 atmos- 

 pheres. If the results obtained be correct it would follow that the in- 

 verse pressure law does not apply in this region. 



On the other hand, it is just possible that one is not justified in 

 assuming the effective cross section of the flow of currents between 

 the electrodes to be the area of the opening in the ebonite plate EF. 

 There would be a tendency for the ions in passing across the field 

 to diffuse to the walls of this opening and if such diffusion did occur, 

 the effect would be to reduce the effective area of the opening. This 

 would result in the values of the mobilities deduced as above being 

 smaller than they really should be. However, one would scarcely 

 expect the reduction from values calculated on the basis of the in- 

 verse pressure law to be so great as that indicated by the numbers 

 given in Table VII. 



