﻿imparted 
  to 
  certain 
  Salts 
  by 
  Cathode 
  Rays. 
  197 
  

  

  indicated 
  any 
  loss 
  of 
  charge, 
  it 
  was 
  evident 
  that 
  such 
  loss 
  

   arose 
  from 
  a 
  leakage 
  through 
  the 
  gas 
  surrounding 
  the 
  

   measuring 
  system. 
  Any 
  conduction 
  across 
  the 
  sulphur 
  bead 
  

   could 
  only 
  be 
  in 
  such 
  a 
  direction 
  as 
  to 
  partially 
  counteract 
  

   the 
  loss 
  arising 
  from 
  leakage 
  through 
  the 
  gas. 
  

  

  Fig. 
  1. 
  

  

  In 
  order 
  to 
  get 
  rid 
  of 
  disturbances 
  of 
  the 
  gold 
  leaf 
  by 
  air- 
  

   currents 
  set 
  up 
  on 
  applying 
  heat 
  to 
  the 
  base 
  of 
  the 
  electro- 
  

   scope, 
  the 
  observations 
  were 
  made 
  generally 
  at 
  a 
  pressure 
  

   of 
  15 
  mms. 
  of 
  mercury. 
  

  

  III. 
  Methods 
  of 
  making 
  Salts 
  Radioactive. 
  

  

  In 
  the 
  initial 
  stages 
  of 
  the 
  investigation 
  the 
  salts 
  to 
  be 
  

   tested 
  for 
  radioactivity 
  were 
  subjected 
  to 
  bombardment 
  by 
  

   cathode 
  rays 
  in 
  a 
  tube 
  similar 
  to 
  that 
  shown 
  in 
  fig. 
  2 
  (p. 
  198) 
  . 
  

   This 
  tube, 
  while 
  carrying 
  but 
  a 
  single 
  anode, 
  was 
  provided 
  

   with 
  a 
  number 
  of 
  cathodes 
  so 
  that 
  several 
  salts 
  could 
  be 
  

   simultaneously 
  exposed. 
  

  

  The 
  salts 
  were 
  generally 
  exposed 
  to 
  the 
  rays 
  for 
  half 
  an 
  

   hour, 
  and 
  from 
  time 
  to 
  time 
  during 
  exposure 
  were 
  gently 
  

  

  