﻿S. 
  B. 
  Kuzirian 
  — 
  Use 
  of 
  the 
  Sodium 
  P 
  availing 
  state. 
  311 
  

  

  scopicity 
  of 
  the 
  fluoride, 
  and 
  the 
  consequently 
  greater 
  part 
  

   played 
  by 
  water 
  in 
  ignition. 
  

  

  In 
  expelling 
  fluorine 
  from 
  fluorides, 
  with 
  the 
  use 
  of 
  the 
  

   blowpipe 
  flame, 
  free 
  hydrofluoric 
  acid 
  is 
  evolved, 
  and 
  so 
  the 
  

   determinations 
  must 
  be 
  carried 
  out 
  under 
  a 
  good 
  draft 
  hood. 
  

   Being 
  slightly 
  volatile, 
  sodium 
  fluoride 
  may, 
  on 
  ignition 
  with 
  

   the 
  paratungstate, 
  escape 
  somewhat 
  as 
  such, 
  unless 
  steps 
  be 
  

   taken 
  to 
  prevent 
  loss 
  by 
  carefully 
  moderating 
  the 
  heat. 
  The 
  

   author's 
  method 
  of 
  overcoming 
  this 
  source 
  of 
  error 
  is, 
  to 
  cover 
  

   the 
  bottom 
  of 
  the 
  platinum 
  crucible 
  with 
  paratungstate, 
  to 
  

   add 
  the 
  fluoride 
  and 
  cover 
  it 
  with 
  another 
  weighed 
  portion 
  of 
  

   sodium 
  paratungstate, 
  to 
  fuse 
  with 
  a 
  very 
  gentle 
  flame 
  of 
  the 
  

   Bunsen 
  burner, 
  and 
  then 
  to 
  apply 
  the 
  usual 
  blowpipe 
  flame. 
  

   The 
  covering 
  layer 
  of 
  paratungstate 
  serves 
  as 
  a 
  trap 
  to 
  hold 
  

   back 
  the 
  somewhat 
  volatile 
  fluoride. 
  

  

  The 
  paratungstate 
  used 
  must, 
  of 
  course, 
  be 
  free 
  from 
  mate- 
  

   rial 
  volatile 
  in 
  the 
  ignition, 
  and 
  this 
  condition 
  is 
  easily 
  fulfilled 
  

   by 
  subjecting 
  the 
  paratungstate 
  to 
  a 
  preliminary 
  ignition 
  in 
  

   the 
  superheated 
  steam 
  of 
  the 
  blowpipe 
  flame 
  directed 
  upon 
  it 
  

   from 
  above. 
  The 
  expulsion 
  of 
  the 
  volatile 
  halogen 
  from 
  a 
  

   fluoride 
  can 
  be 
  completed 
  within 
  less 
  than 
  five 
  minutes. 
  

  

  In 
  Table 
  YI 
  are 
  given 
  the 
  results 
  of 
  the 
  estimation 
  of 
  

   fluorine 
  in 
  sodium 
  fluoride. 
  

  

  

  

  

  

  Table 
  VI. 
  

  

  

  

  

  Analysis 
  < 
  

  

  3/C. 
  

  

  P. 
  Sodium 
  

  

  i, 
  Fluoride 
  of 
  Commerce, 
  after 
  

  

  Drying. 
  

  

  No. 
  

  

  ' 
  NaP 
  

   taken 
  

   grm. 
  

  

  Na 
  

  

  10 
  W 
  ]2 
  O 
  41 
  

   taken 
  

   grm. 
  

  

  Loss 
  on 
  

  

  ignition 
  

  

  grm. 
  

  

  Theory 
  

  

  for 
  loss 
  

  

  grm! 
  

  

  Error 
  

   grm. 
  

  

  1 
  

  

  o 
  

  

  3 
  

   4 
  

   5 
  

  

  0-2000 
  

   0*2000 
  

   0-2000 
  

   0-2000 
  

   A 
  0-2000 
  

  

  

  3 
  

   3 
  

   3 
  

   3 
  

   3 
  

  

  0-0531 
  

   0-0531 
  

   0-0522 
  

   0-0526 
  

   0-0528 
  

  

  0-0524 
  

   0-0524 
  

   0-0524 
  

   0-0524 
  

   0-0524 
  

  

  -0-0007 
  

  

  — 
  0-0007 
  

   + 
  0-0002 
  

   —0-0002 
  

  

  — 
  0-0004 
  

  

  Summary. 
  

  

  Sodium 
  paratungstate 
  of 
  the 
  composition 
  5Na 
  2 
  0.12W0 
  3 
  , 
  an 
  

   acidic 
  salt 
  capable 
  of 
  combining 
  with 
  metallic 
  oxides 
  in 
  a 
  state 
  

   of 
  fusion 
  to 
  form 
  tungstates 
  with 
  the 
  quantitative 
  expulsion 
  of 
  

   certain 
  volatile 
  acid 
  radicals, 
  is 
  easily 
  prepared 
  by 
  fusing 
  sodium 
  

   tungstate 
  with 
  an 
  equal 
  weight 
  of 
  tungsten 
  trioxide, 
  the 
  acidic 
  

   salt 
  thus 
  formed 
  being 
  readily 
  fusible, 
  and 
  not 
  volatile 
  under 
  

   the 
  conditions 
  of 
  this 
  work. 
  It 
  is 
  not 
  more 
  than 
  ordinarily 
  

   hygroscopic 
  and 
  can 
  easily 
  be 
  kept 
  dry 
  in 
  a 
  desiccator 
  over 
  sul- 
  

   phuric 
  acid. 
  The 
  duration 
  of 
  ignition 
  is 
  remarkably 
  short, 
  as 
  

   compared 
  with 
  the 
  time 
  required 
  in 
  the 
  case 
  of 
  other 
  fluxes 
  

  

  