﻿Gooch 
  and 
  Morley 
  — 
  Determination 
  of 
  Gold. 
  

  

  263 
  

  

  molecule 
  of 
  auric 
  chloride 
  (or 
  every 
  atom 
  of 
  gold) 
  present, 
  

   and 
  that 
  the 
  thiosulphate 
  acts 
  only 
  upon 
  the 
  free 
  iodine 
  to 
  

   form 
  the 
  tetrathionate 
  in 
  the 
  usual 
  manner, 
  every 
  cubic 
  centi- 
  

   meter 
  of 
  the 
  thiosulphate 
  solution 
  used 
  in 
  the 
  reaction 
  after 
  

   deducting 
  the 
  amount 
  equivalent 
  to 
  the 
  iodine 
  introduced 
  to 
  

   get 
  the 
  end-color, 
  should 
  represent 
  

  

  197-3 
  __„,„ 
  „ 
  

  

  

  

  2(158-22) 
  

  

  /\ 
  '-' 
  "'-'J 
  ' 
  

  

  Table 
  I. 
  

  

  v/^ww. 
  5^" 
  

  

  .. 
  v,x 
  gv^.vx. 
  

  

  

  

  

  Gold 
  chloride 
  

  

  

  = 
  OSnO 
  to 
  1 
  liter. 
  

  

  

  

  

  Sodium 
  th 
  

   Iodine, 
  ne 
  

  

  losulphate, 
  

   '^^^^ 
  100' 
  

  

  nearly 
  ^^^ 
  , 
  

  

  = 
  1-1012 
  

   = 
  1-3697 
  

  

  11 
  a 
  

  

  

  

  

  Yolume 
  at 
  beginning 
  

  

  of 
  titration, 
  

  

  approximately 
  50<="^^ 
  

  

  

  

  AuCl, 
  

  

  KI 
  

  

  NasSsOa 
  

  

  Gold 
  

  

  Theory 
  

  

  

  

  

  taken 
  

  

  taken. 
  

  

  used. 
  

  

  found. 
  

  

  for 
  gold. 
  

  

  Error. 
  

  

  

  

  cm^. 
  

  

  grm. 
  

  

  cm^. 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  Per 
  cent. 
  

  

  ( 
  1) 
  

  

  5 
  

  

  0-05 
  

  

  4-02 
  

  

  0-00426 
  

  

  0-00435 
  

  

  — 
  0-00009 
  

  

  2-1 
  

  

  ( 
  2) 
  

  

  (( 
  

  

  (( 
  

  

  4-01 
  

  

  0-00425 
  

  

  0-00435 
  

  

  -0-00010 
  

  

  2-3 
  

  

  (3) 
  

  

  u 
  

  

  u 
  

  

  4-06 
  

  

  0-00431 
  

  

  0-00435 
  

  

  — 
  0-00004 
  

  

  0-9 
  

  

  ( 
  4) 
  

  

  u 
  

  

  (( 
  

  

  4-07 
  

  

  0-00482 
  

  

  0-00435 
  

  

  -0-00003 
  

  

  0-7 
  

  

  ( 
  5) 
  

  

  (( 
  

  

  (( 
  

  

  4-04 
  

  

  0-00428 
  

  

  0-00435 
  

  

  — 
  0-00007 
  

  

  1-6 
  

  

  ( 
  6) 
  

  

  10 
  

  

  0-08 
  

  

  8 
  17 
  

  

  0-00867 
  

  

  0-00871 
  

  

  -0-00004 
  

  

  0-5 
  

  

  { 
  ^7) 
  

  

  u 
  

  

  u 
  

  

  8-15 
  

  

  0-00864 
  

  

  0-00871 
  

  

  — 
  0-00007 
  

  

  0-8 
  

  

  ( 
  8) 
  

  

  (( 
  

  

  (.<. 
  

  

  8-16 
  

  

  0-00865 
  

  

  0-00871 
  

  

  -0-00006 
  

  

  0-7 
  

  

  ( 
  9) 
  

  

  u 
  

  

  (( 
  

  

  815 
  

  

  0-00864 
  

  

  0-00871 
  

  

  -0-00007 
  

  

  0-8 
  

  

  (10) 
  

  

  (( 
  

  

  a 
  

  

  8-19 
  

  

  0-00869 
  

  

  0-00871 
  

  

  — 
  0-00002 
  

  

  0-2 
  

  

  (11) 
  

  

  « 
  

  

  (( 
  

  

  8-46 
  

  

  0-00897 
  

  

  0-00871 
  

  

  + 
  0-00026 
  

  

  3-0 
  

  

  (12) 
  

  

  (( 
  

  

  (( 
  

  

  8-24 
  

  

  0-00874 
  

  

  0-00871 
  

  

  + 
  0-00003 
  

  

  0-3 
  

  

  Plainly, 
  these 
  results 
  accord 
  reasonably 
  with 
  the 
  theory 
  that 
  

   two 
  molecules 
  of 
  the 
  thiosulphate 
  are 
  the 
  equivalent 
  in 
  this 
  

   reaction 
  of 
  two 
  atoms 
  of 
  iodine 
  and 
  one 
  atom 
  of 
  gold. 
  There 
  

   is 
  no 
  evidence 
  whatever 
  of 
  the 
  excessive 
  action 
  affirmed 
  by 
  

   Peterson. 
  

  

  The 
  strength 
  of 
  the 
  standard 
  solutions 
  used 
  in 
  the 
  experi- 
  

   ments 
  described 
  was 
  such 
  that 
  an 
  error 
  of 
  0-01^"^ 
  in 
  reading 
  

   the 
  volumes 
  used 
  would 
  correspond 
  to 
  an 
  error 
  of 
  0-00001 
  grm. 
  

   of 
  gold. 
  It 
  is 
  not 
  to 
  be 
  expected 
  that 
  such 
  readings 
  can 
  be 
  

   trusted 
  ordinarily 
  to 
  a 
  higher 
  degree 
  of 
  accuracy 
  than 
  0-02^"l 
  

   In 
  case 
  all 
  three 
  solutions 
  should 
  be 
  read 
  to 
  this 
  limit 
  of 
  accu- 
  

   racy 
  with 
  the 
  errors 
  of 
  all 
  lying 
  in 
  the 
  same 
  direction, 
  the 
  

   summation 
  of 
  error 
  would 
  correspond 
  to 
  0-00006 
  grm. 
  of 
  gold. 
  

  

  In 
  the 
  following 
  experiments, 
  therefore, 
  solutions 
  obtained 
  

   by 
  properly 
  diluting 
  those 
  of 
  the 
  previous 
  series 
  were 
  employed. 
  

   The 
  use 
  of 
  a 
  more 
  dilute 
  solution 
  of 
  gold 
  obviated 
  the 
  neces- 
  

  

  