﻿426 
  Penfield- 
  — 
  Chemical 
  Composition 
  of 
  Sulphohalite. 
  

  

  and 
  the 
  specimen 
  can 
  be 
  so 
  held 
  that 
  only 
  small 
  portions 
  of 
  

   these 
  are 
  visible. 
  The 
  second 
  specimen, 
  fig. 
  2, 
  consists 
  of 
  a 
  

   group 
  of 
  three 
  large 
  and 
  a 
  few 
  small 
  hanksite 
  crystals 
  upon 
  

   which 
  a 
  number 
  of 
  sulphohalite 
  dodecahedrons 
  have 
  grown. 
  

   The 
  figure 
  is 
  merely 
  a 
  sketch, 
  hence 
  it 
  is 
  not 
  to 
  be 
  considered 
  

   as 
  an 
  exact 
  crystal 
  drawing 
  ; 
  however, 
  pains 
  have 
  been 
  taken 
  

   to 
  represent 
  the 
  crystals 
  in 
  their 
  proper 
  size 
  and 
  proportions, 
  

   and, 
  for 
  the 
  sake 
  of 
  distinctness, 
  the 
  hanksite 
  crystals 
  have 
  

   been 
  stippled. 
  All 
  of 
  the 
  sulphohalite 
  crystals 
  are 
  distributed 
  

   on 
  one 
  side 
  of 
  this 
  specimen 
  only. 
  

  

  The 
  writer's 
  attention 
  was 
  directed 
  to 
  the 
  desirability 
  of 
  

   reinvestigating 
  this 
  species 
  by 
  the 
  following 
  circumstances 
  : 
  

   In 
  January 
  of 
  the 
  previous 
  year, 
  a 
  letter 
  was 
  received 
  from 
  

   Prof. 
  A. 
  de 
  Schulten 
  of 
  the 
  University 
  of 
  Helsingfors, 
  Fin- 
  

   land, 
  stating 
  that 
  he 
  had 
  repeatedly 
  attempted 
  to 
  reproduce 
  

   sulphohalite 
  artificially, 
  but 
  always 
  obtained 
  sodium 
  chloride 
  

   and 
  sodium 
  sulphate, 
  crystallizing 
  respectively 
  as 
  halite 
  and 
  

   thenardite. 
  As 
  he 
  was 
  unable 
  to 
  obtain 
  specimens 
  of 
  sulpho- 
  

   halite 
  from 
  mineral 
  dealers, 
  he 
  appealed 
  to 
  the 
  writer 
  to 
  make 
  

   if 
  possible 
  a 
  new 
  analysis 
  of 
  the 
  mineral, 
  and, 
  if 
  this 
  should 
  

   conform 
  to 
  the 
  composition 
  as 
  given 
  by 
  Mackintosh, 
  he 
  

   expressed 
  his 
  determination 
  to 
  proceed 
  with 
  his 
  endeavors 
  to 
  

   make 
  the 
  mineral 
  by 
  artificial 
  means. 
  A 
  short 
  time 
  previous, 
  

   in 
  an 
  article 
  entitled 
  " 
  Die 
  Bildungsverhdltnisse 
  der 
  ocean- 
  

   ischen 
  Salzablagerungen" 
  by 
  J. 
  H. 
  van't 
  Hoff 
  and 
  A. 
  P. 
  

   Saunders,* 
  reviewed 
  in 
  this 
  Journal, 
  f 
  the 
  probable 
  non-exist- 
  

   ence 
  of 
  sulphohalite 
  had 
  been 
  set 
  forth. 
  This 
  decision 
  was 
  

   based 
  chiefly 
  upon 
  the 
  failure 
  of 
  these 
  investigators 
  to 
  obtain 
  

   by 
  artificial 
  means 
  a 
  double 
  sulphate 
  and 
  chloride 
  of 
  sodium 
  

   corresponding 
  to 
  the 
  composition 
  as 
  given, 
  by 
  Mackintosh, 
  

   their 
  experiments, 
  like 
  those 
  of 
  de 
  Schulten, 
  yielding 
  crystals 
  

   of 
  halite 
  and 
  thenardite. 
  They 
  furthermore 
  endeavored 
  to 
  

   secure 
  sulphohalite 
  specimens 
  from 
  dealers, 
  and 
  two 
  that 
  were 
  

   sent 
  to 
  them 
  proved 
  upon 
  examination 
  to 
  be 
  simply 
  halite. 
  

   Lastly, 
  a 
  request 
  came 
  from 
  Mr. 
  Hidden 
  that 
  the 
  writer 
  should 
  

   make 
  a 
  new 
  analysis 
  of 
  sulphohalite, 
  for 
  the 
  purpose 
  of 
  defi- 
  

   nitely 
  establishing 
  the 
  identity 
  of 
  the 
  species 
  and 
  its 
  chemical 
  

   composition, 
  and 
  the 
  request 
  was 
  accompanied 
  by 
  the 
  gift 
  of 
  

   the 
  precious 
  material. 
  

  

  The 
  material 
  submitted 
  for 
  examination 
  was 
  part 
  of 
  a 
  rhom- 
  

   bic 
  dodecahedron 
  which 
  must 
  have 
  originally 
  measured 
  about 
  

   3Qmm 
  j 
  n 
  di 
  ame 
  ter. 
  To 
  it 
  were 
  attached 
  several 
  small 
  prismatic 
  

   crystals 
  of 
  hanksite. 
  The 
  sulphohalite 
  material 
  was 
  clear, 
  

   transparent, 
  and 
  homogeneous, 
  and 
  when 
  tested 
  with 
  the 
  polar- 
  

  

  * 
  Sitzungsberichte 
  der 
  K. 
  Akad., 
  Berlin, 
  1898, 
  vol. 
  i, 
  p. 
  387. 
  

   fVol. 
  iv, 
  p. 
  511, 
  1898. 
  

  

  