﻿Pen 
  field 
  — 
  Chemical 
  Composition 
  of 
  Snip 
  hohalite. 
  427 
  

  

  izing 
  microscope 
  it 
  was 
  found 
  to 
  be 
  isotropic. 
  The 
  fracture 
  is 
  

   small 
  conchoidal, 
  and 
  the 
  absence 
  of 
  any 
  distinct 
  cleavage 
  is 
  

   noticeable, 
  thus 
  distinguishing 
  it 
  from 
  halite. 
  The 
  material 
  

   for 
  analysis, 
  after 
  being 
  carefully 
  selected, 
  was 
  crushed 
  and 
  

   sifted 
  to 
  a 
  nearly 
  uniform 
  grain, 
  and 
  separated 
  by 
  means 
  of 
  

   methylen 
  iodide 
  diluted 
  with 
  benzol. 
  Nearly 
  all 
  of 
  the 
  

   material 
  ranged 
  in 
  specific 
  gravity 
  within 
  the 
  narrow 
  limits 
  

   2493 
  and 
  2-506. 
  The 
  average 
  of 
  these 
  determinations, 
  2*500, 
  

   may 
  be 
  taken 
  as 
  the 
  correct 
  specific 
  gravity, 
  which 
  is 
  close 
  to 
  

   that 
  given 
  by 
  Hidden 
  and 
  Mackintosh, 
  2*489. 
  The 
  material 
  

   thus 
  separated, 
  when 
  tested 
  with 
  acid, 
  gave 
  no 
  effervescence, 
  

   thus 
  indicating 
  perfect 
  separation 
  from 
  hanksite. 
  A 
  few 
  frag- 
  

   ments, 
  mostly 
  hanksite, 
  which 
  were 
  heavier 
  than 
  the 
  product 
  

   separated 
  for 
  analysis, 
  effervesced 
  with 
  acids, 
  hence 
  failure 
  to 
  

   make 
  a 
  complete 
  separation 
  from 
  hanksite 
  undoubtedly 
  

   accounted 
  for 
  the 
  small 
  percentage 
  of 
  Na 
  2 
  C0 
  3 
  recorded 
  in 
  

   Mackintosh's 
  analysis. 
  

  

  After 
  completing 
  the 
  quantitative 
  determinations 
  of 
  CI, 
  S0 
  3 
  

   and 
  Na 
  2 
  0, 
  the 
  constituents 
  required 
  by 
  the 
  formula 
  as 
  given 
  

   by 
  Mackintosh, 
  a 
  deficiency 
  was 
  noted 
  in 
  the 
  analysis, 
  which 
  

   for 
  a 
  time 
  proved 
  very 
  perplexing, 
  but 
  led 
  finally 
  to 
  the 
  dis- 
  

   covery 
  of 
  another 
  and 
  rather 
  unexpected 
  constituent, 
  namely 
  

   fluorine. 
  In 
  recording 
  the 
  analysis, 
  sufficient 
  sodium 
  has 
  been 
  

   taken 
  to 
  combine 
  with 
  the 
  chlorine 
  and 
  fluorine 
  to 
  form 
  the 
  

   molecules 
  XaCl 
  and 
  NaF, 
  respectively, 
  while 
  the 
  remainder 
  

   of 
  the 
  sodium 
  is 
  given 
  as 
  oxide. 
  

  

  The 
  results 
  of 
  the 
  analysis 
  are 
  as 
  follows 
  : 
  

  

  

  

  Ratio 
  

  

  Calculated 
  for 
  

  

  Results 
  of 
  

  

  

  

  

  x 
  

  

  9Nn„SO 
  NTafl 
  "NTa^ 
  "vr 
  Q 
  /VL-*«f«oTi 
  

  

  so 
  3 
  

  

  41*79 
  

  

  •522 
  

  

  2-00 
  

  

  41-61 
  

  

  42-48 
  

  

  Na.0 
  

  

  32*37 
  

  

  •522 
  

  

  2-00 
  

  

  32-25 
  

  

  

  K,0 
  

  

  Na 
  

  

  0*10 
  

   11-60 
  

  

  

  

  11-97 
  

  

  

  CI 
  

  

  9-10 
  

  

  •256 
  

  

  0*98 
  

  

  9-23 
  

  

  13-12 
  

  

  F 
  

  

  4-71 
  

  

  •248 
  

  

  0-95 
  

  

  4*94 
  

  

  

  Ign 
  

  

  0*15 
  

  

  

  

  

  Na 
  2 
  C0 
  3 
  1-77 
  

  

  99-82 
  100-00 
  

  

  The 
  ratio 
  of 
  S0 
  3 
  : 
  Na 
  2 
  : 
  CI 
  : 
  F 
  approximates 
  closely 
  to 
  2 
  : 
  2 
  : 
  

   1 
  : 
  1, 
  and 
  since 
  the 
  sodium 
  (Na) 
  recorded 
  is 
  just 
  sufficient 
  to 
  

   unite 
  with 
  the 
  chlorine 
  and 
  fluorine, 
  the 
  formula 
  of 
  sulphoha- 
  

   lite 
  becomes 
  2Na 
  2 
  S0 
  4 
  .NaCl.NaF. 
  Fluorine 
  was 
  weighed 
  

   as 
  calcium 
  fluoride, 
  and 
  the 
  purity 
  of 
  the 
  product 
  was 
  proved 
  

   by 
  converting 
  it 
  into 
  calcium 
  sulphate. 
  It 
  is 
  interesting 
  to 
  

   note 
  the 
  association 
  of 
  this 
  mineral, 
  having 
  three 
  acid 
  constit- 
  

   uents, 
  with 
  hanksite, 
  which 
  also 
  has 
  three 
  acid 
  constituents, 
  

  

  