Thermions emitted by the Alkali Sulphates. 989 



experiments are considered. The numerical results are 

 exhibited together in the following table : — 



Lithium Sulphate — Positive Jons. 



Substance. 



Pt .... 

 Li 2 SO^ 



Time 



heated 

 (hours). 



z 

 (cms.) 



V 



(Volts). 



H 



(lines 

 per cm. 2 ) 



X 



(1=063 



cm.*). 



ejm 



(E.M. 

 units). 



m 



(H=l). 



32-5 







•483 



200 



4700 



•99 



297 







•485 



200 



4700 



•95 



269 



35-9 



12 



■477 



200 



4700 



•85 



231 



41-8* 



12 



•477 



200 



470J 



2-35 



1760 



5-5 t 



44 



•479 



200 



4700 



2 35 



1735 



557 



52 



•481 



200 



4700 



205 



1300 



7-43 



70 



•4835 



200 



4700 



125 



470 



206 



* The value calculated from the two inside humps. 

 t The value calculated from the two outside humps. 



The first column gives the material experimented with, the 

 second shows the time the lithium sulphate had been heated, 

 the third gives the distance in cms. between the back of the 

 strip and the plate, the sixth gives half the displacement of 

 the maximum produced by reversing the magnetic field given 

 in the fifth column, whilst the meaning of the numbers in 

 the remaining columns are obvious. The values of m repre- 

 sent the ratio of the mass of the ions to that of an atom of 

 hydrogen on the assumption that the ions carry the same 

 charge as that carried by an atom of* hydrogen in electrolysis. 

 The value of e/m for hydrogen was taken to be 9' 6 6 X 10 3 

 E.M. units. 



The value of m for the platinum ions (32*5) is not very 

 different from the mean (25*7) of the values given by 

 Richardson and Hulbirt*, and is within the limits of the 

 range of values found by them. On the view that the 

 positive ions emitted by 'hot metals are due to the presence 

 of alkaline impurities, this value would correspond to that 

 from a mixture of potassium (atomic weight ,5 9* 15) and 

 s idium (atomic weight 2305). This is on the assumption 

 that the ions are positively charged atoms of the metals in" 

 question. We shall see that this is substantiated in so far 

 that the positive ions emitted by the sulphates of the alkali 

 metals are atoms of the metals they contain. 



The value of m for the ions from fresh lithium sulphate 

 (35' 9) is very near the atomic weight of potassium, and is in 



*' Lac. tit. -'■.. 



