﻿Ionization by Positive Rays. 787 



that it was also sufficient to ensure that all the electrons 

 liberated at C were absorbed in D. If i 4 is the current 

 which with this arrangement is received by D, then 

 i 4 = I 3 and F=—iJii- i\ was measured as before by with- 

 drawing the plate to 0. No precise measurements of Ii 

 could be made in this case, but everything pointed to it being 

 not greater than 0'02. 



5. For values of V which were obtainable by means of 

 cells, the homogeneity of the rays was investigated by 

 noting the variation of i x when the potential of B, C, and 

 D was varied relative to A. It was found that, when B, C, D 

 were raised from the potential of A to very nearly that of S 

 the value of i ± did not decrease 10 per cent. ; accordingly at 

 least 90 per cent, of the rays entering B and striking 

 must have had an energy not differing by more than 1 or 

 2 volts from V. Similar experiments were difficult when 

 the influence-machine or induction-coil were used to obtain 

 V, for the potential obtained in this manner is not perfectly 

 steady ; their variations caused large induced currents in C. 

 But there is no reason to suppose that if a small steady value 

 of V gives homogeneous rays, a large steady value should 

 give heterogeneous rays — so long, of course, as there is no 

 sign of an ordinary discharge passing between S and A. 

 The current between S and A was approximately saturated 

 when V was 250 volts, but continued to increase slightly up 

 to the highest potentials used. 



Fig. 2. 



-?- 



O Induction Coil 

 ^Influence Machine 

 'Cells 



2CO0O 30000 40000 



i obtained are shown in fio-s. 



6. The result 

 Fi<>'s. 2 and 3 give the results for P, fi 



3E 2 



50000 



3, 4, 



4 those for R. 



