﻿Brackett 
  and 
  Williams 
  — 
  Xewtonite 
  and 
  Rectorite. 
  17 
  

  

  stained 
  with 
  hydrous 
  oxide 
  of 
  iron 
  and 
  present 
  a 
  reddish-brown 
  

   appearance. 
  The 
  sheets 
  tear 
  apart 
  easily 
  and 
  are 
  very 
  flexible 
  

   and 
  perfectly 
  non-elastic. 
  Some 
  specimens 
  of 
  this 
  mineral 
  

   have 
  been 
  obtained 
  through 
  the 
  kindness 
  of 
  Mr. 
  Charles 
  F. 
  

   Brown, 
  of 
  Hot 
  Springs, 
  in 
  which 
  fine 
  doubly 
  terminated 
  quartz 
  

   crystals 
  are 
  imbedded. 
  Some 
  of 
  the 
  latter 
  are 
  at 
  least 
  one 
  and 
  

   a 
  half 
  inches 
  in 
  length 
  and 
  when 
  surrounded 
  by 
  the 
  rectorite 
  

   form 
  very 
  beautiful 
  and 
  striking 
  specimens. 
  The 
  hardness 
  of 
  

   rectorite 
  is 
  less 
  than 
  that 
  of 
  talc 
  — 
  say 
  0'5 
  — 
  although 
  this 
  is 
  

   difficult 
  to 
  estimate 
  exactly. 
  When 
  heated 
  in 
  the 
  flame 
  of 
  a 
  

   Bnnsen 
  burner 
  it 
  loses 
  water 
  and 
  becomes 
  brittle. 
  It 
  is 
  infusi- 
  

   ble 
  before 
  the 
  blowpipe. 
  Its 
  behavior 
  when 
  treated 
  with 
  sul- 
  

   phuric 
  acid 
  and 
  caustic 
  potash 
  will 
  be 
  explained 
  below. 
  

  

  Two 
  quantitative 
  chemical 
  analyses 
  gave 
  the 
  following 
  per- 
  

   centage 
  composition 
  calculated 
  on 
  the 
  material 
  dried 
  at 
  110° 
  C. 
  : 
  

  

  V. 
  VI. 
  

  

  Si0 
  o 
  52-72 
  52*88 
  

  

  A] 
  o 
  3 
  36-60 
  35-51 
  

  

  Fefl 
  3 
  ] 
  f 
  0-25 
  0-25 
  

  

  CaO 
  | 
  | 
  0-45 
  0-45 
  

  

  Mo^O 
  y 
  once 
  determined 
  <{ 
  0-51 
  0*51 
  

  

  KjO 
  | 
  I 
  0-26 
  0-26 
  

  

  Na 
  2 
  OJ 
  L 
  2 
  ' 
  83 
  2 
  ' 
  83 
  

  

  Loss 
  on 
  ignition 
  7*76 
  772 
  

  

  Total 
  101-38 
  100-41 
  

  

  Water 
  at 
  110° 
  C 
  8*78 
  8*33 
  

  

  If 
  these 
  analyses 
  be 
  brought 
  to 
  100 
  per 
  cent, 
  then 
  all 
  save 
  

   silica, 
  alumina, 
  and 
  loss 
  on 
  ignition 
  be 
  disregarded 
  and 
  the 
  

   analyses 
  again 
  calculated 
  to 
  100 
  per 
  cent, 
  the 
  following 
  figures 
  

   result 
  : 
  

  

  Theoretical 
  for 
  

   Va. 
  Via. 
  Alo0 
  3 
  .2Si0 
  2 
  .H 
  2 
  0. 
  

  

  Si0 
  -.. 
  54-32 
  55*01 
  4999 
  

  

  A1 
  2 
  3 
  37*69 
  36-96 
  42-52 
  

  

  Loss 
  on 
  ignition 
  7*99 
  8-03 
  7 
  -49 
  

  

  100-00 
  100-00 
  100-00 
  

  

  If 
  the 
  calculations 
  be 
  made 
  on 
  the 
  air-dried 
  material 
  the 
  

   following 
  figures 
  are 
  obtained 
  : 
  

  

  VIb. 
  

  

  Si0 
  o 
  50-18 
  

  

  Al 
  2 
  6 
  3 
  __._.- 
  33-72 
  

  

  Loss 
  on 
  ignition 
  7*32 
  

  

  Water 
  at 
  110°-115° 
  C 
  8-78 
  

  

  100-00 
  

   Am. 
  Jour. 
  Sci.— 
  Third 
  Series. 
  Vol. 
  XLII, 
  No. 
  247.— 
  July, 
  1891. 
  

  

  