﻿218 
  Gooch 
  and 
  Gruener 
  — 
  Method 
  for 
  the 
  Determination 
  

  

  oxidizer 
  before 
  and 
  after 
  reduction. 
  The 
  best 
  method 
  of 
  

   proceeding 
  appears 
  to 
  be 
  that 
  in 
  which 
  the 
  concentration 
  was 
  

   restricted 
  so 
  that 
  the 
  point 
  of 
  sublimation 
  and 
  crystallization 
  

   was 
  not 
  reached 
  and 
  in 
  which 
  the 
  presence 
  of 
  an 
  excess 
  of 
  

   potassium 
  iodide 
  was 
  assured. 
  

  

  It 
  seemed 
  desirable, 
  in 
  this 
  connection, 
  to 
  test 
  the 
  applica- 
  

   bility 
  of 
  the 
  method, 
  as 
  outlined, 
  to 
  the 
  reduction 
  and 
  estima- 
  

   tion 
  of 
  antimony 
  and 
  arsenic 
  associated 
  together, 
  as 
  so 
  often 
  

   happens 
  in 
  practice. 
  The 
  preceding 
  experiments 
  establish 
  the 
  

   fact 
  that 
  it 
  is 
  undesirable 
  to 
  attempt, 
  in 
  treating 
  antimony, 
  to 
  

   force 
  the 
  concentration 
  of 
  the 
  solution 
  below 
  50 
  cm. 
  3 
  , 
  under 
  

   the 
  conditions 
  laid 
  down 
  and 
  when 
  the 
  amount 
  of 
  antimony 
  

   present 
  is 
  equivalent 
  to 
  the 
  maximum 
  with 
  which 
  we 
  have 
  

   experimented, 
  about 
  0*2 
  grm. 
  of 
  antimonious 
  oxide. 
  In 
  the 
  

   parallel 
  process 
  for 
  the 
  determination 
  of 
  arsenic 
  concentration 
  

   to 
  40 
  cm 
  3 
  was 
  recommended 
  in 
  all 
  cases 
  (the 
  maximum 
  amount 
  

   treated 
  being 
  equivalent 
  to 
  about 
  0*33 
  grm. 
  of 
  arsenious 
  

   oxide), 
  but 
  it 
  was 
  not 
  shown 
  in 
  the 
  elaboration 
  of 
  that 
  process 
  

   that 
  reduction 
  would 
  not 
  take 
  place 
  at 
  a 
  concentration 
  not 
  

   quite 
  so 
  extreme. 
  In 
  the 
  results 
  recorded 
  in 
  Table 
  V, 
  which 
  

   relate 
  to 
  experiments 
  which 
  duplicate 
  the 
  conditions 
  found 
  

   most 
  favorable 
  to 
  the 
  reduction 
  of 
  varying 
  amounts 
  of 
  anti- 
  

   mony, 
  — 
  the 
  presence 
  of 
  the 
  equivalent 
  of 
  1*1 
  grm. 
  of 
  potassium 
  

   iodide, 
  and 
  concentration 
  to 
  50 
  cm 
  3 
  — 
  and 
  differ 
  from 
  these 
  only 
  

   in 
  the 
  fact 
  that 
  arsenic 
  was 
  associated 
  with 
  antimony 
  in 
  every 
  

   case, 
  it 
  appears 
  that 
  the 
  reduction 
  of 
  arsenic 
  may 
  be 
  effected 
  

   simultaneously 
  with 
  that 
  of 
  the 
  antimony. 
  

  

  Table 
  IY. 
  

  

  is 
  

   > 
  

  

  Tartar 
  

   Emetic 
  

   taken. 
  

  

  Sb 
  2 
  3 
  

   taken. 
  

  

  As 
  2 
  3 
  

   taken. 
  

  

  Iodine 
  used 
  

  

  in 
  first 
  

   oxidation. 
  

  

  Iodine 
  used 
  

  

  in 
  final 
  

   oxidation. 
  

  

  Difference 
  

   between 
  the 
  

   amounts 
  of 
  

   iodine 
  used 
  

   in 
  the 
  two 
  

   oxidations. 
  

  

  Error 
  in 
  

   Sbo0 
  3 
  

  

  terms 
  of 
  

   As 
  2 
  3 
  . 
  

  

  cm. 
  3 
  

   50 
  

   50 
  

   50 
  

   50 
  

  

  grm. 
  

  

  0-1530 
  

  

  0-1503 
  

  

  0-1503 
  

  

  01503 
  

  

  grm. 
  

  

  0-0870 
  

   00855 
  

   0-0855 
  

   0-0855 
  

  

  grm. 
  

  

  0-0500 
  

  

  0-0495 
  

  

  00544 
  

  

  0-0495 
  

  

  cm. 
  3 
  

  

  19-37 
  

  

  19-05 
  

  

  20-05 
  

  

  19-05 
  

  

  cm. 
  3 
  

   1943 
  

   19-02 
  

   19-97 
  

   19-00 
  

  

  cm. 
  3 
  

   0-06 
  + 
  

   0-03- 
  

  

  0-08- 
  

   0-05- 
  

  

  grm. 
  

   0-0004 
  + 
  

   0-0002- 
  

   0-0006 
  — 
  

   0-0004- 
  

  

  grm. 
  

   0-0003- 
  

  

  o-oooi- 
  

  

  0-0004- 
  

   0-0003 
  + 
  

  

  It 
  is 
  plain 
  that 
  the 
  error 
  in 
  these 
  results, 
  whether 
  reckoned 
  

   as 
  falling 
  upon 
  the 
  antimonious 
  oxide 
  or 
  upon 
  the 
  arsenious 
  

   oxide, 
  is 
  quite 
  within 
  the 
  limits 
  allowable 
  in 
  volumetric 
  deter- 
  

   minations 
  by 
  means 
  of 
  decinormal 
  solutions. 
  One 
  point, 
  

   however, 
  in 
  the 
  determination 
  of 
  the 
  combined 
  amounts 
  of 
  

   antimony 
  and 
  arsenic 
  by 
  the 
  method 
  here 
  proposed 
  deserves 
  

   special 
  consideration. 
  It 
  has 
  been 
  shown 
  in 
  the 
  work 
  to 
  which 
  

   reference 
  has 
  been 
  made 
  that 
  arsenic 
  is 
  reducible 
  by 
  the 
  pro- 
  

  

  