﻿Radioactivity 
  of 
  Potassium 
  and 
  other 
  Alkali 
  Metals. 
  387 
  

  

  the 
  more 
  active 
  the 
  radioactivities 
  were 
  approximately 
  pro- 
  

   portional 
  to 
  the 
  potassium 
  contents 
  of 
  the 
  salts. 
  The 
  results 
  

   obtained 
  with 
  potassium 
  cyanide 
  in 
  this 
  series 
  of 
  measure- 
  

   ments, 
  therefore, 
  rather 
  support 
  the 
  view 
  taken 
  by 
  Campbell 
  

   that 
  the 
  activities 
  of 
  potassium 
  salts 
  are 
  directly 
  proportional 
  

   to 
  the 
  amount 
  of 
  potassium 
  present 
  in 
  them. 
  

  

  In 
  the 
  light 
  of 
  these 
  results 
  it 
  would 
  appear 
  advisable, 
  too, 
  

   before 
  drawing 
  definite 
  conclusions 
  from 
  the 
  numbers 
  given 
  

   in 
  Table 
  V., 
  to 
  make 
  a 
  chemical 
  analysis 
  of 
  each 
  of 
  the 
  salts 
  

   and 
  to 
  accurately 
  determine 
  its 
  potassium 
  content. 
  

  

  VI. 
  Absorption 
  Experiments. 
  

  

  In 
  order 
  to 
  obtain 
  an 
  estimate 
  of 
  the 
  penetrating 
  power 
  of 
  

   the 
  radiations 
  emitted 
  by 
  the 
  potassium 
  salt, 
  quantities 
  of 
  the 
  

   sulphate, 
  the 
  chloride, 
  and 
  the 
  cyanide 
  were 
  spread 
  in 
  turn 
  

   in 
  uniform 
  layers 
  on 
  a 
  tray 
  and 
  placed 
  beneath 
  and 
  close 
  to 
  

   the 
  bottom 
  of 
  the 
  ionizing 
  chamber 
  AB, 
  fig. 
  1. 
  In 
  these 
  

   measurements 
  the 
  bottom 
  of 
  the 
  chamber 
  consisted 
  of 
  a 
  finely 
  

   meshed 
  gauze, 
  which 
  permitted 
  the 
  rays 
  to 
  pass 
  into 
  the 
  

   chamber 
  with 
  as 
  little 
  absorption 
  as 
  possible. 
  The 
  tray 
  con- 
  

   taining 
  the 
  salt 
  was 
  then 
  gradually 
  lowered 
  so 
  as 
  to 
  increase 
  

   the 
  air-column 
  traversed 
  by 
  the 
  rays 
  before 
  they 
  entered 
  the 
  

   chamber, 
  and 
  the 
  ionization 
  currents 
  were 
  measured 
  with 
  

  

  Table 
  VII. 
  

   Absorption 
  Experiments. 
  

  

  Distance 
  

  

  (cm.). 
  

  

  Potassium. 
  

  

  Sulphate 
  (Current 
  

   arbitrary 
  scale). 
  

  

  Chloride 
  (Current 
  

   arbitrary 
  scale). 
  

  

  Cyanide 
  (Current 
  

   arbitrary 
  scale). 
  

  

  2-1 
  

  

  178 
  

  

  235 
  

  

  240 
  

  

  4-7 
  

  

  158 
  

  

  200 
  

  

  205 
  

  

  9-1 
  

  

  118 
  

  

  166 
  

  

  178 
  

  

  166 
  

  

  81 
  

  

  94 
  

  

  125 
  

  

  244 
  

  

  59 
  

  

  654 
  

  

  96 
  

  

  319 
  

  

  39 
  

  

  44 
  

  

  64 
  

  

  39-1 
  

  

  28-5 
  

  

  

  33 
  

  

  the 
  salt 
  at 
  different 
  distances. 
  The 
  values 
  of 
  the 
  currents 
  

   obtained 
  with 
  three 
  of 
  the 
  salts 
  mentioned 
  are 
  shown 
  in 
  

   Table 
  VII. 
  These 
  values 
  have 
  been 
  reduced 
  for 
  purposes 
  of 
  

   comparison 
  to 
  a 
  common 
  maximum 
  intensity, 
  and 
  the 
  reduced 
  

  

  2 
  D2 
  

  

  

  