﻿248 
  F. 
  W. 
  Clarke 
  and 
  E. 
  A. 
  Schneider 
  — 
  Constitution 
  of 
  

  

  an 
  optical 
  examination 
  by 
  Mr. 
  Lindgren 
  the 
  matrix 
  of 
  the 
  

   " 
  painterite 
  " 
  is 
  a 
  mixture 
  of 
  plagioclase, 
  probably 
  labradorite 
  r 
  

   with 
  serpentine. 
  The 
  " 
  painterite 
  " 
  itself 
  shows 
  hexagonal 
  

   markings 
  on 
  the 
  surface, 
  and 
  contains, 
  Mr. 
  Lindgren 
  says, 
  in- 
  

   clusions 
  of 
  ferric 
  oxide. 
  Optically 
  he 
  found 
  it 
  to 
  show 
  slight 
  

   double 
  refraction 
  between 
  crossed 
  nicols, 
  the 
  angle 
  of 
  the 
  

   optical 
  axes 
  being 
  small 
  but 
  distinct. 
  In 
  the 
  Newlin 
  mineral 
  

   the 
  axial 
  angle 
  was 
  usually 
  large, 
  being 
  at 
  least 
  25°. 
  Analysis 
  

   as 
  follows 
  : 
  A, 
  Newlin. 
  B, 
  Painterite 
  from 
  Jefferis. 
  C, 
  Pain- 
  

   terite 
  collected 
  by 
  Schneider. 
  D, 
  matrix 
  of 
  painterite. 
  

  

  

  A. 
  

  

  B. 
  

  

  c. 
  

  

  D. 
  

  

  Si0 
  2 
  

  

  31*23 
  

  

  34-86 
  

  

  33-95 
  

  

  52-47 
  

  

  Ti0 
  2 
  

  

  

  

  trace 
  

  

  trace 
  

  

  none 
  

  

  Al 
  2 
  O 
  a 
  

  

  17-52 
  

  

  11-64 
  

  

  12-52 
  

  

  21*72 
  

  

  o 
  2 
  o 
  3 
  

  

  0-14 
  

  

  

  

  

  

  

  

  Fe 
  2 
  3 
  

  

  4-70 
  

  

  3-78 
  

  

  4-40 
  

  

  1-23 
  

  

  FeO 
  

  

  1-20 
  

  

  0-20 
  

  

  0-20 
  

  

  0.17 
  

  

  MnO 
  

  

  0-20 
  

  

  

  

  

  

  

  

  NiO 
  

  

  0-33 
  

  

  0-14 
  

  

  ,0-23 
  

  

  

  

  MgO 
  

  

  31-36 
  

  

  31-32 
  

  

  30-56 
  

  

  9-26 
  

  

  CaO 
  

  

  

  

  0-07 
  

  

  none 
  

  

  3*25 
  

  

  K 
  2 
  

  

  

  

  

  

  

  

  0-63 
  

  

  Na 
  2 
  

  

  

  

  

  

  

  

  5-09 
  

  

  H 
  2 
  G, 
  105° 
  

  

  1-08 
  

  

  1-64 
  

  

  1-56 
  

  

  1-14 
  

  

  " 
  250°-300 
  

  

  ° 
  0-40 
  

  

  1-03 
  

  

  0-59 
  

  

  

  

  " 
  ignition 
  

  

  12-35 
  

  

  15-75 
  

  

  16-46 
  

  

  4-74 
  

  

  100-31 
  100-43 
  100-47 
  99*70 
  

  

  Upon 
  treating 
  the 
  three 
  vermiculites 
  with 
  gaseous 
  hydro- 
  

   chloric 
  acid 
  at 
  383°-412°, 
  the 
  following 
  results 
  were 
  obtained 
  : 
  

  

  

  

  

  A. 
  

  

  B. 
  

  

  c. 
  

  

  Hours 
  heated 
  

  

  

  8 
  

  

  iH 
  

  

  19 
  

  

  R 
  2 
  O 
  s 
  removed 
  

  

  

  1-09 
  

  

  •80 
  

  

  •78 
  

  

  MgO 
  

  

  ' 
  

  

  

  5-86 
  

  

  8*26 
  

  

  9-56 
  

  

  Molec. 
  ratio 
  MgOH 
  

  

  •146 
  

  

  •207 
  

  

  •239 
  

  

  molecular 
  

  

  ratios 
  

  

  are 
  : 
  

  

  

  

  

  

  

  A. 
  

  

  B. 
  

  

  

  c. 
  

  

  Si0 
  2 
  

  

  

  •520 
  

  

  •581 
  

  

  

  •566 
  

  

  R 
  2 
  3 
  

  

  

  •202 
  

  

  •138 
  

  

  

  •150 
  

  

  RO 
  

  

  

  •808 
  

  

  * 
  -789 
  

  

  

  •770 
  

  

  H 
  2 
  

  

  

  •675 
  

  

  •875 
  

  

  

  •914 
  

  

  Aq 
  

  

  

  •080 
  

  

  •148 
  

  

  

  •119 
  

  

  In 
  these 
  examples 
  the 
  water 
  (Aq) 
  expelled 
  below 
  300° 
  is 
  so 
  

   small 
  in 
  amount 
  that 
  it 
  may 
  be 
  left 
  out 
  of 
  consideration. 
  Part 
  

   of 
  it 
  undoubtedly 
  represents 
  hydrated 
  molecules, 
  which, 
  how- 
  

   ever, 
  are 
  relatively 
  so 
  few 
  in 
  number 
  that 
  they 
  may 
  be 
  for 
  

   present 
  purposes 
  disregarded. 
  

  

  