﻿Browning 
  — 
  Estimation 
  of 
  Thallium. 
  . 
  137 
  

  

  Akt. 
  XIII. 
  — 
  On 
  the 
  Estimation 
  of 
  Thallium 
  as 
  the 
  acid 
  

   and 
  neutral 
  Sulphates 
  ; 
  by 
  Philip 
  E. 
  Browning. 
  

  

  [Contributions 
  from 
  the 
  Kent 
  Chemical 
  Laboratory 
  of 
  Yale 
  University 
  — 
  XCIIL] 
  

  

  Crookes* 
  has 
  shown 
  that 
  the 
  salt 
  obtained 
  by 
  heating 
  thal- 
  

   lous 
  chloride 
  with 
  sulphuric 
  acid 
  until 
  the 
  excess 
  of 
  the 
  latter 
  

   is 
  expelled 
  and 
  then 
  raising 
  the 
  heat 
  to 
  redness 
  has 
  the 
  consti- 
  

   tution 
  of 
  a 
  neutral 
  sulphate. 
  

  

  He 
  also 
  found 
  that 
  continued 
  heating 
  did 
  not 
  result 
  in 
  any 
  

   essential 
  loss 
  of 
  weight, 
  and 
  suggested 
  the 
  possibility 
  of 
  apply- 
  

   ing 
  this 
  method 
  of 
  treatment 
  to 
  the 
  estimation 
  of 
  thallium. 
  

  

  Castanjenf 
  in 
  a 
  recent 
  paper 
  discusses 
  thoroughly 
  the 
  com- 
  

   pounds 
  of 
  thallium 
  and 
  confirms 
  essentially 
  the 
  statements 
  of 
  

   Crookes 
  in 
  regard 
  to 
  the 
  neutral 
  sulphate, 
  adding, 
  however, 
  the 
  

   observation 
  that 
  on 
  strong 
  ignition 
  in 
  the 
  air 
  this 
  salt 
  tends 
  to 
  

   lose 
  sulphuric 
  acid. 
  He 
  also 
  mentions 
  in 
  the 
  same 
  paper 
  the 
  

   acid 
  sulphate 
  and 
  states 
  that 
  on 
  heating 
  it 
  first 
  melts 
  and 
  on 
  

   continued 
  heating 
  gives 
  off 
  sulphuric 
  acid, 
  leaving 
  the 
  neutral 
  

   sulphate. 
  

  

  The 
  work 
  to 
  be 
  described 
  in 
  this 
  paper 
  was 
  undertaken 
  to 
  

   determine 
  under 
  what 
  conditions 
  the 
  formation 
  of 
  these 
  salts 
  

   may 
  be 
  applied 
  to 
  the 
  estimation 
  of 
  thallium. 
  For 
  the 
  work 
  a 
  

   solution 
  was 
  made 
  by 
  dissolving 
  a 
  given 
  amount 
  of 
  the 
  nitrate 
  

   in 
  water 
  and 
  making 
  up 
  to 
  a 
  liter. 
  The 
  value 
  of 
  the 
  solution 
  

   was 
  determined 
  by 
  precipitating 
  measured 
  and 
  weighed 
  

   amounts 
  of 
  this 
  solution 
  both 
  as 
  the 
  iodide 
  and 
  chromate, 
  as 
  

   described 
  in 
  a 
  previous 
  paper.:); 
  Closely 
  agreeing 
  results 
  by 
  

   both 
  methods 
  were 
  taken 
  as 
  the 
  standard. 
  Measured 
  amounts 
  

   of 
  this 
  solution 
  were 
  drawn 
  from 
  a 
  burette 
  into 
  weighed 
  plati- 
  

   num 
  crucibles, 
  and 
  the 
  weight 
  taken 
  as 
  a 
  check 
  on 
  the 
  burette 
  

   reading. 
  To 
  the 
  solution 
  in 
  the 
  crucible 
  a 
  few 
  drops 
  of 
  sul- 
  

   phuric 
  acid 
  was 
  added 
  and 
  the 
  water 
  removed 
  by 
  evaporation 
  

   over 
  a 
  steam 
  bath. 
  The 
  crucible 
  was 
  then 
  removed 
  to 
  a 
  radi- 
  

   ator, 
  consisting 
  in 
  this 
  work 
  of 
  a 
  conical 
  iron 
  cup, 
  and 
  heated 
  

   at 
  a 
  temperature 
  ranging 
  from 
  220° 
  C. 
  to 
  240° 
  C., 
  until 
  fum- 
  

   ing 
  ceased 
  and 
  the 
  weight 
  after 
  half 
  hour 
  periods 
  of 
  heating 
  

   remained 
  constant. 
  The 
  crucibles 
  were 
  placed 
  in 
  a 
  radiator 
  

   upon 
  a 
  pipe 
  stem 
  triangle 
  so 
  that 
  they 
  were 
  about 
  5 
  cm 
  from 
  the 
  

   bottom, 
  which 
  was 
  heated 
  at 
  low 
  redness. 
  A 
  thermometer 
  

   hung 
  so 
  that 
  the 
  bulb 
  occupied 
  the 
  same 
  position 
  as 
  the 
  crucible 
  

   gave 
  the 
  reading 
  mentioned 
  above. 
  

  

  As 
  will 
  be 
  seen, 
  the 
  results 
  obtained 
  by 
  this 
  treatment 
  agree 
  

   closely 
  with 
  the 
  calculated 
  amounts 
  of 
  acid 
  sulphate 
  which 
  

  

  *Chem. 
  News, 
  viii, 
  243. 
  \ 
  Jour. 
  f. 
  prakt. 
  Chem., 
  cii, 
  131. 
  

  

  \ 
  This 
  Journal, 
  viii, 
  460. 
  

  

  