096 Prof. 0. \Y. Richardson on the Positive 



below it. However, the difference is not greater than the 

 error of observation might well account for. 



The specimen of rubidium sulphate used was purchased 

 from Messrs. Eimer and Amend. It was not stated to be 

 especially pure. 



I '.i'.sioi Sulphate. 



Two -ets of observations were made with the ionization 

 from the fresh platinum strip used in this experiment, one 

 immediately after the heating was started and the other a 

 tew hours later. The firsl led to the values 2#=2*05 turns, 

 ( 'hi =344, w=28 , 2 J and the second. 2#= 1*95 turns, e/m=2i)5, 

 m=32*7. 



This increase with lapse of time in the value of m for 

 the ions from platinum is in agreement with that already 

 ssed under the heading of pot>issium sulphate. 



The following data were the same for all the experiments 

 in this series, whether with platinum alone or with caesium 

 sulphate: — 7=200 volts, 11=4700 lines per cm. 2 , and 

 ,- = 474 cm. 



The results of the observations on caesium sulphate are all 

 shown in fig. 11. The firsl two curves, points : — x,were 

 taken immediately after the heating bad Btarted. It will be 

 noticed that these are distinctly broader than the later 

 curves, and the displacement of the maximum was greater. 

 The displacement in this case was 2#= 1*125 turns, giving 

 t m»= L01-8, m=!>5. 



The curves with points ® were obtained after eighteen 

 hours beating. The displacement now is 2, /' = '*;"> turns, 

 giving i m = .">;>• 1 and m — 163. The remaining curves, 

 points ® and • . represent the results after twenty-three 

 hours heating. The displacement is again 2./'=*$5 turns, 

 giving the same values of e/m and >» as the last. 



It may be that the greater breadth of the curves and the 

 greater displacement of the maxima obtained initially repre- 

 sents a real difference in the ionization. It is, however, 

 difficult to be certain about the mater, as the displacements 

 with these heavy ions are small, and the probable experi- 

 mental error is correspondingly great. The mean of the 

 three measurements gives m — 140. The atomic weight of 

 csesium is given as 133*9 



The specimen of cesium sulphate used was prepared by 

 the action of pure sulphuric acid on the chloride. The 

 latter was bought from Messrs. Eimer and Amend, with no 

 specification as to its purity. 



