﻿600 
  Gooch, 
  etc. 
  — 
  Dehydration 
  and 
  Recovery 
  of 
  Silica. 
  

  

  Table 
  I. 
  

  

  Ignition 
  of 
  Commercial) 
  "Analyzed" 
  Silica. 
  

  

  Hydrous 
  Weight 
  of 
  SiO 
  a 
  found 
  

  

  Silica 
  taken 
  After 
  heating 
  with 
  the 
  After 
  heating 
  with 
  

  

  (Approximate 
  Bunsen 
  burner, 
  the 
  blast 
  lamp 
  

  

  weight) 
  in 
  half 
  -hoar 
  heats 
  in 
  15 
  minute 
  heats 
  

  

  I 
  II 
  I 
  II 
  III 
  

  

  grm. 
  grm. 
  grm. 
  grm. 
  grm. 
  grin. 
  

  

  A 
  

  

  0-2 
  0-1008 
  0-1006 
  0-1006 
  

  

  0-4 
  0-1930 
  0-1929 
  0*1926 
  

  

  0*4 
  0-1968 
  0-1967 
  0*1966 
  

  

  0-5 
  0-2501 
  0-2500 
  0'2500 
  

  

  1-0 
  0-4568 
  0-4568 
  0-4568 
  

  

  1-1 
  0-5343 
  0-5333 
  0-5330 
  0*5330 
  

  

  1-1 
  0-5309 
  0*5304 
  05306 
  0'5302 
  0*5302 
  

  

  1*1 
  0*5325 
  0-5327 
  0'5323 
  0*5324 
  

  

  1-1 
  0*5374 
  0*5372 
  0*5373 
  

  

  1*1 
  0-5392 
  0*5381 
  0-5381 
  

  

  1*1 
  0*5353 
  0*5351 
  0*5347 
  0*5347 
  

  

  B 
  

  

  1*0 
  0*5464 
  0*5454 
  0*5447 
  0*5445 
  0*5444* 
  

  

  1-0 
  0*5206 
  0*5204 
  0*5202 
  0*5202 
  0*5202 
  

  

  1*0 
  0*5447 
  0*5443 
  0*5441 
  0*5439 
  0*5439* 
  

  

  1*0 
  0*5346 
  0*5346 
  0*5342 
  0*5342 
  0*5342 
  

  

  1*0 
  0*5427 
  0*5427 
  0*5427 
  0-5427 
  

  

  1*0 
  0-5376 
  0-5373 
  0-5373 
  0-5372* 
  

  

  1-0 
  0*5511 
  05511 
  0*5511 
  0*5511 
  

  

  1*0 
  0-5445 
  0-5445 
  0-5444 
  0-5443 
  

  

  1*0 
  0-5344 
  0-5343 
  0'5340 
  0*5338 
  0*5338 
  

  

  1-0 
  0-5513 
  0-5513 
  0-5513 
  0*5512 
  

  

  1*0 
  0*5312 
  0-5312 
  0'5311 
  0-5311 
  

  

  1*0 
  0*5536 
  0-5536 
  0*5531 
  0'5531 
  

  

  was 
  moistened 
  with 
  acetic 
  anhydride 
  and 
  warmed 
  over 
  a 
  radia- 
  

   tor 
  until 
  this 
  reagent 
  fumed 
  freely, 
  the 
  object 
  of 
  this 
  treatment 
  

   being 
  to 
  thoroughly 
  desiccate 
  the 
  silica 
  while 
  preventing 
  the 
  

   otherwise 
  possible 
  formation 
  of 
  sodium 
  silicate 
  by 
  action 
  

   between 
  silica, 
  included 
  sodium 
  chloride, 
  and 
  water. 
  Each 
  of 
  

   these 
  methods 
  of 
  treatment 
  leaves 
  the 
  silica 
  drier, 
  more 
  porous, 
  

   and, 
  therefore, 
  more 
  effectively 
  washable 
  than 
  is 
  the 
  case 
  when 
  

   drying 
  is 
  brought 
  about 
  by 
  the 
  steam 
  bath 
  only. 
  The 
  results 
  

   of 
  these 
  experiments 
  are 
  given 
  in 
  the 
  following 
  table. 
  Every 
  

   residue 
  of 
  silica 
  was 
  treated, 
  after 
  the 
  final 
  ignition, 
  with 
  sul- 
  

   phuric 
  acid 
  and 
  hydrofluoric 
  acid, 
  the 
  amount 
  of 
  sodium 
  

   sulphate 
  remaining 
  was 
  weighed, 
  and 
  the 
  equivalent 
  weight 
  of 
  

   the 
  combined 
  sodium 
  oxide 
  was 
  calculated. 
  

  

  * 
  It 
  was 
  found 
  that 
  the 
  crucible 
  used 
  in 
  this 
  determination 
  was 
  subject 
  to 
  

   loss 
  when 
  ignited 
  by 
  itself 
  over 
  the 
  blast 
  lamp. 
  

  

  