﻿504 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  31 
  at 
  unlike 
  kaolinite 
  in 
  its 
  behavior, 
  as 
  shown 
  by 
  the 
  experiments 
  

   of 
  Vogt, 
  its 
  presence 
  may 
  be 
  of 
  no 
  influence, 
  unless 
  there 
  is 
  an 
  

   appreciable 
  amount 
  of 
  it. 
  The 
  following 
  quotation^ 
  exhibits 
  those 
  

   experiments. 
  

  

  ]Mr 
  Yogt 
  considers 
  that 
  the 
  plasticity 
  which 
  clays 
  have 
  is 
  chiefly 
  

   due 
  to 
  the 
  hydrated 
  silicate 
  of 
  alumina 
  or 
  kaolinite. 
  Experiments 
  

   which 
  he 
  made, 
  show 
  that 
  the 
  kaolinite 
  is 
  not 
  the 
  only 
  substance 
  

   which 
  remains 
  in 
  suspension 
  for 
  a 
  long 
  period. 
  For 
  his 
  trials 
  he 
  

   took 
  quartz 
  from 
  Limousin, 
  orthoclase 
  from 
  J^or^'ay, 
  and 
  a 
  potash 
  

   mica. 
  All 
  three 
  were 
  ground 
  very 
  fine, 
  and 
  then 
  washed 
  in 
  a 
  

   current 
  of 
  slightly 
  ammoniacal 
  water. 
  The 
  washed 
  materials 
  were 
  

   then 
  allowed 
  to 
  stand. 
  After 
  24 
  hours 
  each 
  of 
  the 
  liquids 
  was 
  

   as 
  opalescent 
  as 
  if 
  it 
  had 
  washed 
  clay 
  in 
  suspension. 
  After 
  nine 
  

   dsys 
  the 
  turbidity 
  still 
  remained, 
  but 
  was 
  less 
  marked. 
  At 
  the 
  end 
  

   of 
  this 
  time 
  the 
  supernatant 
  liquid 
  was 
  ladled 
  off 
  of 
  each, 
  and 
  a 
  

   few 
  drops 
  of 
  hydrochloric 
  acid 
  added 
  to 
  it. 
  The 
  suspended 
  ma- 
  

   terials 
  coagulated 
  and 
  settled, 
  and 
  the 
  precipitate 
  was 
  collected, 
  

   dried, 
  and 
  Aveighed. 
  The 
  mica 
  which 
  had 
  remained 
  in 
  suspension 
  

   during 
  the 
  nine 
  days 
  was 
  very 
  fine; 
  still 
  the 
  particles 
  glittered 
  in 
  

   the 
  light. 
  The 
  addition 
  of 
  hydrochloric 
  acid 
  caused 
  the 
  instant 
  

   settling 
  of 
  the 
  particles, 
  which 
  was 
  also 
  noted 
  by 
  the 
  cessation 
  of 
  

   the 
  glittering. 
  The 
  settlings 
  of 
  mica 
  from 
  1 
  liter 
  of 
  water 
  

   amounted 
  to 
  .15 
  gTani. 
  This 
  fine-gTained 
  mica 
  possessed 
  a 
  plas- 
  

   ticity 
  almost 
  equal 
  to 
  that 
  of 
  the 
  kaolin. 
  

  

  From 
  the 
  decanted 
  liquid 
  of 
  the 
  feldspar 
  the 
  hydrochloric 
  acid 
  

  

  brought 
  doAVQ 
  .4 
  gram 
  of 
  this 
  mineral 
  per 
  liter, 
  while 
  of 
  the 
  

  

  quf.rtz 
  only 
  .1 
  g^ani 
  of 
  sediment 
  was 
  obtained. 
  

  

  • 
  A 
  very 
  plastic 
  clay 
  from 
  Dreux 
  was 
  treated 
  in 
  the 
  same 
  manner 
  

  

  and 
  after 
  nine 
  days 
  a 
  precipitate 
  of 
  .56 
  gTani 
  was 
  brought 
  down. 
  

  

  From 
  these 
  experiments 
  we 
  see 
  that 
  in 
  washing 
  kaolin 
  it 
  is 
  

   impossible 
  to 
  free 
  it 
  entirely 
  from 
  quartz, 
  feldspar, 
  and 
  mica. 
  

  

  Asso,ciated 
  with 
  kaolinite 
  we 
  may 
  find 
  one 
  or 
  more 
  other 
  specie^* 
  

   of 
  minerals, 
  all 
  hydrated 
  silicates 
  of 
  alumina. 
  Some 
  of 
  these 
  have 
  

   been 
  found 
  in 
  crystals 
  and 
  are 
  very 
  probably 
  good 
  species, 
  but 
  

   others 
  are 
  known 
  only 
  in 
  an 
  amorphous 
  condition. 
  This 
  may 
  tend 
  

   to 
  suggest 
  some 
  doubt 
  as 
  to 
  their 
  validity. 
  These 
  associated 
  species 
  

   together 
  with 
  their 
  characters 
  are 
  given 
  by 
  Dana 
  as 
  follows. 
  

  

  ' 
  Thonindustrie 
  zeitung, 
  1893. 
  p. 
  140. 
  

  

  