﻿Estimation 
  of 
  Boi'ic 
  Acid. 
  

  

  131 
  

  

  

  

  

  Table 
  II. 
  

  

  

  

  

  B203 
  

  

  Thio. 
  

  

  Iodine 
  

  

  Time 
  

  

  

  B003 
  

  

  B2O3 
  

  

  

  taken. 
  

  

  taken. 
  

  

  taken. 
  

  

  of 
  

  

  Volume. 
  

  

  taken. 
  

  

  found. 
  

  

  Error. 
  

  

  cm^. 
  

  

  cm^. 
  

  

  cm3. 
  

  

  standing 
  

  

  cm^. 
  

   A 
  

   28 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  28-00 
  

  

  32 
  00 
  

  

  1-88 
  

  

  0:30 
  

  

  0-2165 
  

  

  0-2168 
  

  

  + 
  0-0003 
  

  

  2703 
  

  

  32-00 
  

  

  4-37 
  

  

  0:27 
  

  

  27 
  

  

  0-2090 
  

  

  0-2081 
  

  

  -0-0009 
  

  

  27-02 
  

  

  31-97 
  

  

  4 
  04 
  

  

  1:00 
  

  

  27 
  

  

  0-2089 
  

  

  0-2090 
  

  

  + 
  0-0001 
  

  

  27-06 
  

  

  32-04 
  

  

  3-88 
  

  

  1:00 
  

  

  B 
  

   50-60 
  

  

  0-2093 
  

  

  0-2101 
  

  

  + 
  0-0008 
  

  

  27-02 
  

  

  32-02 
  

  

  4-40 
  

  

  1:00 
  

  

  " 
  

  

  0-2089 
  

  

  0-2081 
  

  

  -0-0008 
  

  

  27-04 
  

  

  31-72 
  

  

  3-39 
  

  

  1:00 
  

  

  u 
  

  

  0-2091 
  

  

  0-2096 
  

  

  + 
  00005 
  

  

  27-01 
  

  

  31-53 
  

  

  2-88 
  

  

  2:00 
  

  

  C 
  

  

  0-2089 
  

  

  0-2100 
  

  

  + 
  00011 
  

  

  26-05 
  

  

  3101 
  

  

  4-01 
  

  

  3:00 
  

  

  u 
  

  

  0-2014 
  

  

  0-2025 
  

  

  + 
  0-0011 
  

  

  27-00 
  

  

  31-00 
  

  

  2-12 
  

  

  0:30 
  

  

  

  0-2088 
  

  

  0-2089 
  

  

  + 
  0-0001 
  

  

  27-00 
  

  

  32-00 
  

  

  4-05 
  

  

  0:30 
  

  

  (1 
  

  

  .0-2088 
  

  

  0-2092 
  

  

  + 
  0-0004 
  

  

  26-01 
  

  

  32-02 
  

  

  6-20 
  

  

  0:30 
  

  

  u 
  

  

  0-2011 
  

  

  0-2018 
  

  

  + 
  0-0007 
  

  

  27-03 
  

  

  31-01 
  

  

  2-21 
  

  

  0:48 
  

  

  

  0-2090 
  

  

  0-2087 
  

  

  -0-0003 
  

  

  27-05 
  

  

  31-89 
  

  

  3-81 
  

  

  0:45 
  

  

  u 
  

  

  0-2092 
  

  

  0-2093 
  

  

  + 
  0001 
  

  

  26-07 
  

  

  31-02 
  

  

  4-14 
  

  

  0:40 
  

  

  u 
  

  

  0-2016 
  

  

  0-2020 
  

  

  + 
  0-0004 
  

  

  27-00 
  

  

  3204 
  

  

  4.30 
  

  

  0:40 
  

  

  60 
  

  

  0-2088 
  

  

  0-2086 
  

  

  -0-0002 
  

  

  These 
  results 
  are 
  so 
  regular 
  that 
  the 
  method 
  seems 
  worthy 
  of 
  

   high 
  commendation, 
  and 
  especially 
  since 
  the 
  standard 
  solu- 
  

   tions, 
  thiosulphate 
  and 
  iodine, 
  upon 
  which 
  thej^rocess 
  depends, 
  

   are 
  so 
  easily 
  prepared 
  and 
  generally 
  at 
  hand. 
  

  

  The 
  full 
  method 
  of 
  procedure 
  recommended 
  is 
  as 
  follows 
  : 
  

   The 
  borate 
  is 
  dissolved 
  in 
  as 
  small 
  volume 
  and 
  as 
  little 
  hydro- 
  

   chloric 
  acid 
  as 
  possible, 
  shaking 
  well 
  to 
  remove 
  free 
  carbon 
  

   dioxide 
  and 
  diluting 
  so 
  that, 
  at 
  the 
  time 
  of 
  adding 
  potassium 
  

   iodide 
  and 
  iodate, 
  there 
  shall 
  be 
  approximately 
  25-50'='''^ 
  of 
  

   solution 
  for 
  each 
  decigram 
  of 
  boric 
  anhydride 
  present. 
  The 
  

   greater 
  part 
  of 
  the 
  excess 
  of 
  hydrochloric 
  acid 
  in 
  the 
  solution 
  

   is 
  destroyed 
  by 
  sodium 
  hydroxide 
  and 
  the 
  use 
  of 
  litmus 
  paper, 
  

   leaving 
  the 
  solution 
  distinctly 
  acid 
  in 
  reaction. 
  Potassium 
  

   iodide 
  (S-S'^"^ 
  of 
  a 
  40 
  per 
  cent 
  solution), 
  and 
  iodate 
  (5-10^°^^ 
  of 
  a 
  5 
  

   per 
  cent 
  solution) 
  are 
  added 
  in 
  excess 
  of 
  that 
  required 
  to 
  liber- 
  

   ate 
  iodine 
  in 
  an 
  amount 
  corresponding 
  to 
  the 
  hydrochloric 
  

   acid 
  and 
  the 
  boric 
  acid 
  present. 
  The 
  iodine 
  liberated 
  by 
  the 
  

   free 
  hydrochloric 
  acid 
  is 
  bleached 
  by 
  a 
  small 
  amount 
  of 
  a 
  

   strong 
  solution 
  of 
  thiosulphate, 
  and 
  after 
  agitating 
  to 
  insure 
  

   thorough 
  mixture, 
  iodine 
  is 
  added 
  to 
  faint 
  coloration. 
  Suffi- 
  

   cient 
  mannite 
  is 
  now 
  used 
  to 
  saturate 
  the 
  solution 
  — 
  about 
  

   10-15 
  grm. 
  for 
  a 
  volume 
  of 
  50^™^ 
  — 
  and 
  sodium 
  thiosulphate 
  

   added 
  in 
  standard 
  solution 
  8-10*^'"^ 
  in 
  excess 
  of 
  that 
  required 
  

   to 
  bleach 
  the 
  iodine 
  immediately 
  thrown 
  out 
  by 
  the 
  mannite. 
  

  

  