﻿462 
  Browning 
  and 
  Hutchins 
  — 
  EsUmdtion 
  of 
  Thallium. 
  

  

  to 
  stand 
  a 
  few 
  moments 
  until 
  the 
  change 
  from 
  the 
  yellow 
  to 
  the 
  

   bluish 
  green 
  showed 
  the 
  complete 
  reduction 
  of 
  the 
  chromic 
  

   acid. 
  Potassium 
  bicarbonate 
  was 
  added 
  to 
  distinct 
  alkaline 
  

   reaction 
  and 
  the 
  arsenious 
  oxide 
  remaining 
  was 
  determined 
  by 
  

   titration 
  with 
  standard 
  iodine 
  solution. 
  The 
  amount 
  of 
  the 
  

   arsenious 
  oxide 
  oxidized 
  is 
  of 
  course 
  the 
  measure 
  of 
  the 
  chro- 
  

   mate 
  in 
  the 
  solution. 
  The 
  amount 
  of 
  chromate 
  in 
  the 
  original 
  

   solution 
  used 
  being 
  known, 
  by 
  subtracting 
  the 
  amount 
  thus 
  

   determined 
  in 
  the 
  filtrate, 
  the 
  chromate 
  in 
  combination 
  with 
  

   the 
  thallium 
  may 
  be 
  readily 
  found, 
  and 
  from 
  it 
  the 
  thallium 
  

   estimated. 
  Filtrates 
  from 
  certain 
  precipitates, 
  of 
  which 
  the 
  

   determinations 
  are 
  given 
  in 
  Table 
  I, 
  were 
  treated 
  in 
  this 
  wa}', 
  

   and 
  the 
  results, 
  indicated 
  by 
  corresponding 
  numbers, 
  follow 
  in 
  

   Table 
  11. 
  

  

  

  

  Table 
  11. 
  

  

  

  1 
  

  

  TlNOg 
  taken. 
  

  

  Tl3Gr04 
  found. 
  

  

  Error. 
  

  

  

  Calculated 
  

  

  Calculated 
  

  

  Calculated 
  

  

  

  as 
  TI2O. 
  

  

  asTlaO. 
  • 
  

  

  as 
  TlaO. 
  

  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  (5) 
  

  

  0-1192 
  

  

  0-1198 
  

  

  0-0006 
  + 
  

  

  (^) 
  

  

  0-1-189 
  

  

  0-1205 
  

  

  0-0016 
  + 
  

  

  (^) 
  

  

  0-1196 
  

  

  0-1180 
  

  

  0-0016 
  — 
  

  

  (10) 
  

  

  01196 
  

  

  0-1192 
  

  

  0-0004 
  — 
  

  

  (11) 
  

  

  0-1173 
  

  

  0-1182 
  

  

  0-0009 
  + 
  

  

  (12) 
  

  

  0-1171 
  

  

  0-1190 
  

  

  00019 
  + 
  

  

  The 
  method 
  cannot 
  be 
  very 
  accurate 
  on 
  account 
  of 
  the 
  high 
  

   molecular 
  weight 
  of 
  thallium 
  oxide 
  as 
  compared 
  with 
  that 
  of 
  

   the 
  chromic 
  acid 
  determined, 
  but 
  the 
  results 
  check 
  fairly 
  well 
  

   with 
  the 
  gravimetric 
  method. 
  

  

  July, 
  1899. 
  

  

  