﻿Radioactivity 
  of 
  Potassium 
  and 
  other 
  Alkali 
  Metals. 
  383 
  

  

  measurements 
  was 
  made 
  on 
  the 
  activities 
  of 
  a 
  large 
  number 
  

   of 
  potassium 
  salts 
  as 
  well 
  as 
  on 
  a 
  number 
  of 
  others 
  o£ 
  the 
  

   different 
  alkali 
  metals. 
  

  

  Fio-. 
  5. 
  

  

  ThicKueK 
  of 
  layer 
  

   iri 
  -pm. 
  

  

  

  The 
  results 
  of 
  the 
  examination 
  of 
  these 
  different 
  salts 
  are 
  

   given 
  in 
  Table 
  V. 
  (p. 
  384), 
  and 
  in 
  all 
  cases 
  they 
  represent 
  the 
  

   activities 
  of 
  layers 
  of 
  sufficient 
  thickness 
  to 
  give 
  the 
  maximum 
  

   saturation 
  currents. 
  

  

  From 
  this 
  table 
  it 
  will 
  be 
  seen 
  : 
  — 
  

  

  First. 
  That 
  samples 
  of 
  a 
  selected 
  salt 
  obtained 
  from 
  

   different 
  sources 
  exhibited 
  widely 
  differing 
  degrees 
  of 
  activity. 
  

   Two 
  of 
  the 
  chlorides, 
  as 
  Nos. 
  3 
  and 
  4 
  show, 
  differed 
  by 
  more 
  

   than 
  40 
  per 
  cent, 
  in 
  their 
  activities, 
  and 
  two 
  of 
  the 
  hydroxides, 
  

   Nos. 
  7 
  and 
  8, 
  by 
  nearly 
  an 
  equal 
  amount. 
  In 
  the 
  case 
  of 
  the 
  

   cyanide 
  of 
  potassium 
  the 
  variation 
  in 
  activity 
  was 
  especially 
  

   marked. 
  As 
  can 
  be 
  seen 
  from 
  Nos. 
  10 
  and 
  12, 
  two 
  samples 
  

   of 
  this 
  salt 
  exhibited 
  activities 
  which 
  were 
  approximately 
  

   only 
  5 
  per 
  cent, 
  and 
  20 
  per 
  cent, 
  respectively 
  of 
  that 
  shown 
  

   by 
  a 
  number 
  of 
  other 
  specimens 
  of 
  the 
  same 
  composition. 
  

  

  In 
  addition 
  to 
  the 
  results 
  recorded 
  in 
  Table 
  V. 
  it 
  may 
  be 
  

   stated 
  that 
  on 
  one 
  occasion 
  a 
  sample 
  of 
  potassium 
  cyanide 
  

   obtained 
  from 
  Kahlbaum 
  was 
  compared 
  with 
  one 
  of 
  potassium 
  

   sulphate 
  and 
  one 
  of 
  potassium 
  chloride 
  obtained 
  from 
  Mercks, 
  

  

  