﻿Radioactivity 
  of 
  Potassium 
  and 
  other 
  Alkali 
  Metals. 
  393 
  

  

  VIII. 
  Miscellaneous 
  Experiments. 
  

  

  With 
  a 
  view 
  to 
  ascertaining 
  whether 
  the 
  activity 
  of 
  

   potassium 
  salts 
  arose 
  from 
  the 
  presence 
  in 
  the 
  salts 
  of 
  traces 
  

   of 
  any 
  of 
  the 
  active 
  elements, 
  radium, 
  thorium, 
  or 
  actinium, 
  

   an 
  attempt 
  was 
  made 
  to 
  drive 
  off 
  any 
  emanation 
  which 
  they 
  

   might 
  contain 
  by 
  raising 
  the 
  salts 
  to 
  moderate 
  temperatures. 
  

   Although 
  a 
  number 
  of 
  the 
  salts 
  was 
  treated 
  in 
  this 
  way, 
  witfh 
  

   none 
  of 
  them, 
  however^ 
  was 
  the 
  slightest 
  indication 
  obtained 
  

   of 
  a 
  loss 
  of 
  activity 
  such 
  as 
  should 
  accompany 
  the 
  expulsion 
  

   of 
  radioactive 
  gases. 
  

  

  Although 
  these 
  experiments 
  made 
  it 
  probable 
  that 
  the 
  

   activity 
  was 
  not 
  due 
  to 
  the 
  presence 
  of 
  traces 
  of 
  the 
  elements 
  

   radium, 
  thorium, 
  and 
  actinium, 
  or 
  of 
  their 
  immediate 
  pro- 
  

   ducts, 
  in 
  the 
  salts, 
  it 
  was 
  still 
  possible 
  that 
  the 
  activity 
  might 
  

   be 
  due 
  to 
  the 
  presence 
  in 
  minute 
  quantities 
  of 
  uranium 
  or 
  of 
  

   one 
  of 
  the 
  active 
  products 
  of 
  slow 
  decay 
  of 
  radium. 
  With 
  

   the 
  object 
  of 
  testing 
  this 
  surmise 
  a 
  sample 
  of 
  potassium 
  

   sulphate 
  which 
  had 
  been 
  found 
  to 
  exhibit 
  a 
  comparatively 
  

   high 
  activity 
  was 
  heated 
  to 
  a 
  little 
  over 
  1000° 
  C, 
  and 
  

   maintained 
  at 
  that 
  temperature 
  for 
  a 
  considerable 
  time. 
  

  

  After 
  the 
  salt 
  had 
  been 
  subjected 
  to 
  this 
  treatment 
  it 
  was 
  

   again 
  examined, 
  but 
  was 
  found 
  to 
  possess 
  exactly 
  the 
  same 
  

   activity 
  as 
  before 
  being 
  heated. 
  

  

  Similar 
  attempts 
  were 
  made 
  to 
  reduce 
  the 
  activities 
  of 
  

   samples 
  of 
  potassium 
  chloride 
  and 
  potassium 
  cyanide, 
  but 
  in 
  

   none 
  of 
  these 
  tests 
  was 
  any 
  reduction 
  of 
  activity 
  obtained 
  as 
  

   a 
  result 
  of 
  the 
  heating. 
  

  

  To 
  test 
  still 
  further 
  the 
  possibility 
  of 
  driving 
  off 
  by 
  volati- 
  

   lization 
  any 
  active 
  impurities 
  which 
  might 
  be 
  present, 
  a 
  

   quantity 
  of 
  active 
  potassium 
  sulphate, 
  contained 
  in 
  a 
  graphite 
  

   crucible, 
  which 
  on 
  examination 
  showed 
  no 
  sign 
  of 
  activity, 
  

   was 
  placed 
  in 
  a 
  coke 
  furnace, 
  first 
  melted 
  and 
  then 
  heated 
  

   as 
  highly 
  as 
  possible 
  for 
  a 
  time. 
  During 
  this 
  heating 
  the 
  

   sulphate 
  became 
  partially 
  converted 
  into 
  the 
  sulphides 
  of 
  

   potassium. 
  After 
  cooling, 
  the 
  mixture, 
  which 
  was 
  ground 
  

   to 
  a 
  fine 
  powder 
  and 
  tested 
  for 
  radioactivity 
  in 
  the 
  manner 
  

   indicated 
  above, 
  was 
  found 
  to 
  possess 
  the 
  same 
  activity 
  as 
  

   before 
  the 
  treatment. 
  

  

  As 
  the 
  melting-point 
  of 
  potassium 
  sulphate 
  is 
  approxi- 
  

   mately 
  1060° 
  C, 
  and 
  inasmuch 
  as 
  the 
  temperature 
  of 
  the 
  

   salt 
  during 
  this 
  experiment 
  was 
  raised 
  very 
  much 
  beyond 
  

   this 
  point, 
  it 
  is 
  clear 
  that 
  a 
  temperature 
  was 
  reached 
  con- 
  

   siderably 
  above 
  the 
  points 
  of 
  volatilization 
  of 
  the 
  radium 
  

   products 
  of 
  slow 
  decay, 
  and 
  it 
  follows 
  therefore, 
  from 
  the 
  

   absence 
  of 
  any 
  loss 
  of 
  activity 
  from 
  the 
  heating, 
  that 
  none 
  of 
  

  

  