﻿428 
  Penfield 
  — 
  Chemical 
  Composition 
  of 
  Sulphohalite. 
  

  

  its 
  composition, 
  according 
  to 
  the 
  investigation 
  of 
  Pratt,* 
  being 
  

   9Na 
  2 
  S0 
  4 
  .2Na 
  2 
  C0 
  3 
  .KCl. 
  Although 
  the 
  presence 
  of 
  fluorine 
  

   in 
  sulphohalite 
  was 
  wholly 
  unexpected 
  and 
  seemed 
  at 
  first 
  sur- 
  

   prising, 
  the 
  occurrence 
  of 
  that 
  constituent 
  in 
  some 
  mineral 
  

   from 
  the 
  Borax 
  Lake 
  locality 
  is 
  not 
  to 
  be 
  wondered 
  at. 
  This 
  

   important 
  deposit 
  of 
  borax 
  has 
  been 
  formed 
  undoubtedly 
  from 
  

   fumerole 
  or 
  solfataric 
  action, 
  and 
  it 
  is 
  well 
  established 
  that 
  

   volcanic 
  gases 
  frequently 
  give 
  rise 
  to 
  fluorine 
  as 
  well 
  as 
  to 
  

   boron, 
  chlorine, 
  and 
  sulphuric 
  acid 
  compounds. 
  

  

  Probably 
  the 
  name 
  sulphohalite 
  would 
  not 
  have 
  been 
  given 
  

   to 
  this 
  mineral 
  had 
  its 
  composition 
  been 
  correctly 
  determined 
  

   by 
  Mackintosh; 
  however, 
  one 
  would 
  scarcely 
  be 
  justified 
  at 
  the 
  

   present 
  time 
  in 
  assigning 
  a 
  new 
  name 
  to 
  the 
  compound. 
  To 
  

   a 
  certain 
  extent 
  van't 
  Hoff 
  and 
  Saunders 
  were 
  correct 
  in 
  call- 
  

   ing 
  attention 
  to 
  the 
  probable 
  non-existence 
  of 
  the 
  species, 
  for, 
  

   although 
  the 
  mineral 
  in 
  name 
  and 
  substance 
  had 
  an 
  existence, 
  

   a 
  double 
  salt 
  of 
  the 
  composition 
  3Na 
  2 
  S0 
  4 
  .2NaCl 
  ascribed 
  to 
  

   sulphohalite 
  is 
  not 
  known, 
  and, 
  apparently, 
  cannot 
  be 
  made 
  by 
  

   artificial 
  means. 
  

  

  It 
  is 
  needless 
  to 
  speculate 
  as 
  to 
  how 
  Mackintosh, 
  who 
  was 
  

   an 
  experienced 
  and 
  careful 
  worker, 
  made 
  an 
  erroneous 
  analysis. 
  

   His 
  determination 
  of 
  S0 
  3 
  was 
  nearly 
  correct, 
  while 
  that 
  of 
  chlor- 
  

   ine 
  was 
  four 
  per 
  cent 
  too 
  high. 
  In 
  one 
  respect 
  he 
  certainly 
  

   made 
  a 
  decided 
  mistake, 
  namely 
  in 
  not 
  completing 
  his 
  analysis 
  

   by 
  determining 
  the 
  amount 
  of 
  sodium, 
  for, 
  had 
  he 
  done 
  so, 
  

   he 
  probably 
  would 
  have 
  noted 
  a 
  deficiency 
  and 
  this 
  naturally 
  

   would 
  have 
  led 
  to 
  the 
  discovery 
  of 
  the 
  missing 
  constituent. 
  

  

  Mineralogists 
  certainly 
  are 
  indebted 
  to 
  Mr. 
  Hidden 
  for 
  the 
  

   discovery 
  of 
  this 
  exceptionally 
  beautiful 
  and 
  interesting 
  mineral, 
  

   while 
  his 
  eagerness 
  to 
  have 
  the 
  species 
  correctly 
  investigated, 
  

   together 
  with 
  his 
  generosity 
  in 
  supplying 
  the 
  necessary 
  mate- 
  

   rial 
  have 
  enabled 
  the 
  writer 
  to 
  carry 
  on 
  this 
  investigation. 
  

   Thanks 
  also 
  are 
  due 
  to 
  Mr. 
  Bement 
  for 
  the 
  loan 
  of 
  his 
  valu- 
  

   able 
  specimens. 
  

  

  *This 
  Journal, 
  IV, 
  vol. 
  ii, 
  p. 
  133, 
  1896. 
  

  

  Sheffield 
  Laboratory 
  of 
  Mineralogy 
  and 
  Petrography, 
  

   Tale 
  University, 
  New 
  Haven, 
  March, 
  1900. 
  

  

  