﻿1 
  

  

  

  2 
  

  

  

  8 
  

  

  

  63 
  

  

  .70 
  

  

  49 
  

  

  .20 
  

  

  44, 
  

  

  .10 
  

  

  19 
  

  

  .76 
  

  

  35 
  

  

  .12 
  

  

  40, 
  

  

  .25 
  

  

  13 
  

  

  .61 
  

  

  

  .12 
  

  

  

  ,25 
  

  

  2. 
  

  

  26 
  

  

  

  tr 
  

  

  

  tr 
  

  

  . 
  

  

  71 
  

  

  

  tr 
  

  

  

  tr 
  

  

  

  tr 
  

  

  14, 
  

  

  .20 
  

  

  15. 
  

  

  ,01 
  

  

  CLAYS 
  OF 
  NEW 
  YORK 
  499 
  

  

  With 
  such 
  treatment 
  the 
  orthoolase 
  yielded 
  more 
  readily 
  than 
  

   either 
  albite 
  or 
  oligoclase. 
  The 
  follo'mng 
  analyses 
  show 
  the 
  effect 
  

   of 
  96 
  hours' 
  treatment 
  of 
  orthoclase 
  with 
  hydrofluoric 
  acid 
  at 
  

   60° 
  F. 
  

  

  Silica 
  

  

  Alumina 
  

  

  Potash 
  

  

  Soda 
  

  

  Ferric 
  oxid 
  

  

  Water 
  

  

  100.04 
  98.64 
  99.61 
  

  

  Erom 
  the 
  analysis 
  it 
  will 
  he 
  seen 
  that 
  the 
  composition 
  of 
  the 
  outer 
  

   layer 
  simply 
  approximates 
  that 
  of 
  kaolinite. 
  

  

  ]^o. 
  1 
  is 
  the 
  original 
  feldspar. 
  

  

  'No. 
  2 
  is 
  inner 
  layer 
  of 
  altered 
  feldspar. 
  

  

  ISTo. 
  3 
  is 
  outer 
  layer 
  of 
  altered 
  feldspar. 
  

  

  The 
  artificial 
  clay 
  thus 
  produced, 
  when 
  examined 
  under 
  the 
  

   microscope, 
  resembled 
  washed 
  kaolin. 
  It 
  showed 
  no 
  hexagonal 
  

   scales, 
  but 
  contained 
  a 
  number 
  of 
  minute 
  colorless 
  cubes 
  which 
  are 
  

   supposed 
  to 
  be 
  fluor 
  spar. 
  . 
  

  

  The 
  theory 
  advanced 
  by 
  Mr 
  Collins 
  was 
  first 
  suggested 
  by 
  Yon 
  

   Buch 
  and 
  Daubree, 
  who 
  believed 
  that 
  kaolinization 
  is 
  produced 
  

   by 
  fluids 
  containing 
  fluosilicates 
  or 
  fluoborates 
  acting 
  from 
  below, 
  

   generally, 
  if 
  not 
  always, 
  through 
  fissures. 
  (Annales 
  des 
  mines 
  

   20, 
  1841) 
  ■ 
  

  

  Yon 
  Buch 
  early 
  observed 
  the 
  constant 
  occun'ence 
  of 
  kaolin 
  with 
  

   minerals 
  containing 
  fluorin, 
  and 
  suggested 
  tliat 
  the 
  kaolin 
  of 
  Halle, 
  

   Germany, 
  owed 
  its 
  origin 
  to 
  hydrofluoric 
  acid. 
  (Min. 
  Tascli, 
  

   1824)' 
  

  

  Daubree 
  considered 
  that 
  the 
  kaolin 
  near 
  St 
  Austell 
  in 
  Cornwall 
  

   must 
  have 
  had 
  a 
  similar 
  origin. 
  {Annates 
  des 
  mines 
  1841) 
  

  

  1 
  The 
  writer 
  can 
  state 
  from 
  personal 
  examination 
  that 
  the 
  Halle 
  kaolins 
  

   were 
  formed 
  by 
  ordinary 
  weathering. 
  

  

  