Mobilities of Ions in Air at High Pressures. 489 



III. Results. 



Diagrams similar to that in fig. 2 were plotted from the 

 readings taken with different voltages at all the pressures 

 selected. From them values for ijY 2 were calculated for 

 each of the pressures, and on substituting these values in 

 the relation given by equation (3) the mobilities for both 

 positive and negative ions were deduced for the corre- 

 sponding pressures. These mobilities are all collected in 

 Table II., and they are plotted in fig. 3 against the pressures 

 as abscissaa. 



Fiff. 3. 



140 IfeO ieo *oa 



PRLS5URI ]M ATT- 00. 



Mobilities calculated according fo the inverse-pressure 

 law on the basis of the mobilities for positive and negative 

 ions at atmospheric pressure being respectively 1*34 and 

 1*89 cm. a second per volt a cm. are also given in Table II. 

 The dotted curves represent the calculated mobilities and the 

 smooth curves the mobilities determined in the present in- 

 vestigation. _ As both the table and the figure show, the 

 mobilities did not decrease as the pressure rose so rapidly 

 as was demanded by the inverse-pressure law. Moreover, 



