﻿Gooch 
  — 
  Estimation 
  of 
  Molybdenum 
  fodometrically. 
  239 
  

  

  scrutiny 
  of 
  the 
  figures 
  given 
  by 
  Friedheim 
  and 
  Euler 
  devel- 
  

   opes 
  the 
  fact 
  that 
  the 
  apparent 
  accuracy 
  of 
  their 
  work 
  is 
  

   founded 
  upon 
  miscalculations. 
  This 
  fact 
  was 
  known 
  to 
  us 
  at 
  

   the 
  time 
  of 
  our 
  former 
  writing, 
  but 
  we 
  did 
  not 
  consider 
  it 
  

   essential 
  then 
  to 
  make 
  the 
  matter 
  public. 
  The 
  recent 
  attack 
  of 
  

   Friedheim 
  makes 
  that 
  course 
  now 
  necessary. 
  

  

  Herewith 
  is 
  reproduced 
  a 
  table 
  of 
  results 
  obtained 
  by 
  Fried- 
  

   heim 
  and 
  Euler 
  in 
  the 
  test 
  of 
  their 
  method 
  upon 
  ammonium 
  

   molybdate, 
  shown 
  by 
  analysis 
  to 
  contain 
  81-49 
  per 
  cent, 
  of 
  

   molybdenum 
  trioxide. 
  The 
  figures 
  which 
  are 
  incorrect 
  are 
  

   enclosed 
  in 
  brackets 
  : 
  

  

  Original 
  Figures 
  of 
  Friedheim 
  and 
  

  

  Molybdate 
  

  

  Na 
  2 
  S 
  2 
  3 
  

  

  taken. 
  

  

  used. 
  

  

  grm. 
  

  

  cm 
  3 
  . 
  

  

  0-2674 
  

  

  30-8 
  ) 
  ||| 
  

  

  0-4418 
  

  

  50-8 
  \{%% 
  

  

  0-4075 
  

  

  [40-7]* 
  ) 
  ^©^ 
  

  

  0-3281 
  

  

  37'33 
  "| 
  «o 
  

  

  0-4340 
  

  

  0-4098 
  

  

  49-43 
  ijloo 
  

   46-63 
  [ 
  ! 
  §| 
  

  

  0*4305 
  

  

  49-08 
  J 
  ^ 
  b 
  

  

  Moo 
  3 
  

  

  found. 
  

   grm. 
  

  

  0-2184 
  

   0-3601 
  

   0-3317 
  

   0-2644 
  

   0-3502 
  

   0-3304 
  

   0-3478 
  

  

  Euler. 
  

  

  Per 
  cent 
  of 
  

  

  M0O3 
  referred 
  

  

  to 
  molybdate 
  

  

  taken. 
  

  

  [81 
  

  

  81 
  

  

  •71] 
  

   51 
  

  

  81 
  

   81 
  

  

  •40 
  

  

  •85 
  

  

  81 
  

  

  •69 
  

  

  81 
  

  

  67 
  

  

  81 
  

  

  78 
  

  

  Appended 
  is 
  a 
  recalculation 
  of 
  the 
  percentage 
  of 
  the 
  trioxide 
  

   found, 
  with 
  columns 
  showing 
  the 
  percentage 
  error 
  and 
  the 
  

   error 
  stated 
  in 
  fractions 
  of 
  a 
  gram. 
  Changes 
  from 
  the 
  figures 
  

   of 
  Friedheim 
  and 
  Euler 
  are 
  in 
  heavy-faced 
  type. 
  

  

  Recalculation 
  of 
  the 
  

  

  Results 
  of 
  Friedheim 
  and 
  Euler. 
  

  

  

  Error 
  m 
  

  

  

  Corrected 
  

  

  per 
  cent 
  of 
  

  

  Error 
  

  

  per 
  cent 
  of 
  

  

  M0O3 
  found 
  

  

  of 
  M0O3. 
  

  

  M0O3 
  found, 
  referred 
  

  

  compared 
  with 
  

  

  grm. 
  

  

  to 
  the 
  molybdate. 
  

  

  M0O3 
  taken. 
  

  

  

  81-68 
  

  

  0-23 
  + 
  

  

  0*0005 
  + 
  

  

  81-51 
  

  

  0-03 
  + 
  

  

  0-0001 
  + 
  

  

  81-40 
  

  

  0-12 
  — 
  

  

  0-0004 
  — 
  

  

  80-58 
  

  

  112 
  — 
  

  

  0-0030 
  — 
  

  

  8069 
  

  

  0-99 
  — 
  

  

  00035 
  — 
  

  

  80-62 
  

  

  1-05 
  — 
  

  

  0-0035 
  — 
  

  

  80-79 
  

  

  0-86 
  — 
  

  

  0-0030 
  — 
  

  

  These 
  figures 
  of 
  their 
  own 
  (properly 
  calculated) 
  are 
  suffi- 
  

   cient 
  to 
  show 
  the 
  inadequacy 
  of 
  the 
  method 
  of 
  Friedheim 
  and 
  

   Euler. 
  We 
  ourselves 
  were 
  occasionally 
  able 
  to 
  get 
  results 
  

   from 
  the 
  method 
  of 
  Friedheim 
  and 
  Euler 
  quite 
  as 
  good 
  as 
  

   these 
  ; 
  it 
  must 
  be 
  said, 
  however, 
  that 
  most 
  of 
  our 
  results 
  

  

  Probably 
  46-T. 
  

  

  