﻿Gooch, 
  etc. 
  — 
  Dehydration 
  and 
  Recovery 
  of 
  Silica. 
  601 
  

  

  

  

  Table 
  II. 
  

  

  

  

  Ignition 
  of 
  

  

  silica 
  separated 
  by 
  acid 
  after 
  fusion 
  ivi 
  

  

  th 
  sodium 
  carbonate. 
  

  

  Residue 
  of 
  

   Si0 
  2 
  

   after 
  ignition 
  

   with 
  Bunsen 
  

   burner 
  

  

  Residue 
  of 
  

  

  Si0 
  2 
  after 
  

  

  subsequent 
  

  

  ignition 
  with 
  

  

  blast 
  lamp 
  

  

  Loss 
  on 
  

  

  ignition 
  Na 
  2 
  C0 
  3 
  

  

  with 
  the 
  used 
  in 
  

  

  blast 
  lamp 
  the 
  fusion 
  

  

  Residue 
  after 
  

   H 
  a 
  S0 
  4 
  + 
  HF 
  

   treatment 
  

   Na 
  2 
  S0 
  4 
  ) 
  _ 
  j 
  Na 
  2 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  g 
  rm 
  - 
  

  

  A 
  

  

  Residue 
  dried 
  at 
  110 
  c 
  . 
  

  

  grm. 
  \ 
  

  

  I 
  grm. 
  

  

  0-5300 
  

  

  0-5291 
  

   0-5290 
  

  

  

  

  % 
  

  

  

  0-5287 
  

  

  0-0013 
  4 
  

  

  0-0009 
  

  

  0-0004 
  

  

  0-5380 
  

  

  0-5373 
  

   0-5368 
  

   0-5365 
  

   0-5363 
  

  

  

  

  

  

  0-5363 
  

  

  0-0017 
  4 
  

  

  o-ooio 
  

  

  0-0004 
  

  

  0-5365 
  

  

  0-5360 
  

  

  0-0005 
  4 
  

  

  o-oon 
  

  

  0-0004 
  

  

  0-4583 
  

  

  0-4575 
  

  

  0-0008 
  4 
  

  

  0-0014 
  

  

  0-0006 
  

  

  0-5071 
  

  

  0-5068 
  

  

  0-0003 
  4 
  

  

  0-0015 
  

  

  0-0006 
  

  

  0-5166 
  

  

  0-5159 
  

  

  0-0007 
  4 
  

  

  0-0012 
  

  

  0-0005 
  

  

  B 
  

  

  Residue 
  dehydrated 
  on 
  steam 
  bath 
  and 
  heated 
  with 
  acetic 
  anhydride. 
  

  

  0*1984 
  

  

  0*1980 
  0-1977 
  0-0007 
  2 
  0-0016 
  0-0006 
  

  

  0-4566* 
  0-4564 
  

  

  0-4562 
  0*0004 
  4 
  0'0020 
  0'0008 
  

   0-5322 
  4 
  

  

  0-5325 
  

  

  0-5325 
  0-0003 
  O'OOIO 
  0*0004 
  

  

  A 
  comparison 
  of 
  these 
  results 
  with 
  those 
  of 
  Hillebrand, 
  to 
  

   which 
  reference 
  has 
  been 
  made 
  above, 
  points 
  to 
  the 
  conclusion, 
  

   that 
  the 
  more 
  perfect 
  drying 
  of 
  the 
  silica 
  before 
  attempting 
  the 
  

   process 
  of 
  extraction 
  and 
  washing, 
  results 
  in 
  smaller 
  losses 
  

   when 
  the 
  residue 
  which 
  has 
  been 
  ignited 
  over 
  the 
  Bunsen 
  

   burner 
  is 
  subjected 
  to 
  the 
  heat 
  of 
  the 
  blast 
  lamp. 
  This 
  fact 
  

   suggests 
  that 
  the 
  better 
  desiccation 
  is 
  conducive 
  to 
  the 
  more 
  

   nearly 
  complete 
  washing 
  of 
  soluble 
  material 
  from 
  the 
  precipi- 
  

   tated 
  silica. 
  At 
  the 
  best, 
  however, 
  the 
  separation 
  of 
  foreign 
  

   matter 
  is 
  not 
  perfect, 
  and 
  the 
  presence 
  of 
  material 
  which 
  is 
  dif- 
  

   ficultly 
  volatilized 
  is 
  sufficient 
  to 
  account 
  for 
  the 
  slight 
  changes 
  

   in 
  weight 
  observed 
  when 
  the 
  silica 
  ignited 
  with 
  the 
  Bunsen 
  

   burner 
  is 
  submitted 
  to 
  further 
  heating 
  with 
  the 
  blast 
  flame. 
  

   According 
  to 
  our 
  experience, 
  therefore, 
  the 
  difficulty 
  in 
  bring- 
  

  

  * 
  Ignition 
  extended 
  to 
  one 
  hour. 
  

  

  