﻿Oberhelman 
  and 
  Browning 
  — 
  Tellurotis 
  Acid. 
  399 
  

  

  Art. 
  XXXYII. 
  — 
  On 
  the 
  Preparation 
  of 
  Tellurous 
  Acid 
  and 
  

   Copper 
  Ammonium 
  Tellurite 
  ; 
  by 
  Gr. 
  O. 
  Oberhelman 
  and 
  

   P. 
  E. 
  Browning. 
  

  

  [Contributions 
  from 
  the 
  Kent 
  Chemical 
  Laboratory 
  of 
  Yale 
  Univ. 
  — 
  ccxlix.] 
  

  

  Occasion 
  having 
  arisen 
  to 
  prepare 
  some 
  tellurous 
  acid 
  from 
  

   residues 
  from 
  the 
  electrolytic 
  refining 
  of 
  copper,* 
  residues 
  con- 
  

   taining 
  a 
  high 
  percentage 
  of 
  tellurous 
  oxide 
  together 
  with 
  small 
  

   amounts 
  of 
  silica, 
  copper, 
  selenium, 
  and 
  several 
  other 
  impurities, 
  

   it 
  was 
  determined 
  to 
  try 
  the 
  effect 
  of 
  the 
  solvent 
  action 
  of 
  

   ammonium 
  hydroxide, 
  followed 
  by 
  the 
  precipitation 
  of 
  the 
  

   tellurous 
  acid 
  from 
  the 
  ammoniacal 
  solution 
  by 
  acetic 
  acid. 
  This 
  

   procedure, 
  employed 
  on 
  another 
  occasion 
  for 
  the 
  removal 
  of 
  

   selenium, 
  f 
  proved 
  satisfactory 
  for 
  the 
  removal 
  of 
  the 
  greater 
  

   part 
  of 
  the 
  silica, 
  and 
  of 
  those 
  bases 
  which 
  are 
  insoluble 
  in 
  

   ammonium 
  hydroxide. 
  By 
  dissolving 
  the 
  tellurous 
  acid 
  thus 
  

   obtained 
  in 
  sodium 
  hydroxide 
  and 
  precipitating 
  the 
  tellurous 
  

   acid 
  again 
  by 
  acetic 
  acid, 
  copper 
  and 
  many 
  other 
  metals 
  whose 
  

   hydroxides 
  are 
  insoluble 
  in 
  sodium 
  hydroxide 
  were 
  also 
  removed. 
  

  

  If 
  the 
  precipitation 
  of 
  the 
  tellurous 
  acid 
  by 
  acetic 
  acid 
  is 
  

   brought 
  about 
  without 
  warming 
  the 
  solution, 
  and 
  the 
  product 
  

   is 
  dried 
  without 
  heating, 
  the 
  tellurous 
  acid 
  obtained 
  is 
  readily 
  

   soluble 
  in 
  the 
  alkali 
  hydroxides. 
  If, 
  however, 
  the 
  precipitation 
  

   takes 
  place 
  in 
  hot 
  solution 
  and 
  the 
  precipitate 
  is 
  dried 
  by 
  

   application 
  of 
  heat, 
  the 
  product 
  tends 
  to 
  be 
  quite 
  insoluble 
  in 
  

   the 
  alkali 
  hydroxides. 
  

  

  After 
  the 
  first 
  treatment 
  of 
  the 
  residues 
  with 
  ammonia 
  

   in 
  this 
  extraction 
  process, 
  it 
  was 
  observed 
  that 
  a 
  purple 
  crystal- 
  

   line 
  salt 
  separated 
  from 
  the 
  alkaline 
  solution 
  on 
  standing. 
  The 
  

   color- 
  suggested 
  a 
  copper 
  compound, 
  and 
  after 
  the 
  removal 
  of 
  

   this 
  salt 
  by 
  filtration, 
  the 
  filtrate 
  proved 
  to 
  be 
  practically 
  free 
  

   from 
  copper. 
  It 
  was 
  found 
  that 
  a 
  salt 
  similar 
  in 
  appearance 
  could 
  

   be 
  produced 
  by 
  allowing 
  an 
  ammoniacal 
  solution 
  of 
  tellurous 
  acid 
  

   containing 
  some 
  copper 
  salt 
  to 
  evaporate 
  over 
  sulphuric 
  acid, 
  and 
  

   in 
  the 
  presence 
  of 
  soda-lime. 
  The 
  depth 
  of 
  color 
  varied 
  with 
  the 
  

   concentration 
  of 
  the 
  copper 
  solution 
  from 
  a 
  reddish 
  purple 
  

   through 
  pink 
  to 
  nearly 
  white. 
  It 
  was 
  found 
  that 
  a 
  salt 
  which 
  

   appeared 
  to 
  be 
  identical 
  with 
  the 
  compound 
  just 
  mentioned, 
  

   could 
  be 
  produced 
  by 
  adding 
  slowly, 
  with 
  constant 
  stirring, 
  

   acetic 
  acid 
  to 
  an 
  ammoniacal 
  solution 
  of 
  tellurous 
  oxide 
  and 
  cop- 
  

   per 
  chloride. 
  The 
  precipitate 
  thus 
  obtained 
  proved 
  to 
  be 
  slightly 
  

   soluble 
  in 
  water 
  but 
  insoluble 
  in 
  acetic 
  acid 
  and 
  in 
  50 
  per 
  cent 
  

   alcohol. 
  A 
  sample 
  of 
  this 
  compound 
  prepared 
  in 
  the 
  manner 
  

  

  * 
  Furnished 
  through 
  the 
  kindness 
  of 
  the 
  Baltimore 
  Copper 
  Co. 
  

   f 
  Browning 
  and 
  Flint, 
  this 
  Journal 
  (4), 
  xxviii, 
  112, 
  1909. 
  

  

  