﻿CLAYS 
  OF 
  Is'EW 
  YORK 
  627 
  

  

  the 
  Pennsylvania 
  clays 
  the 
  Yariation 
  was 
  found 
  to 
  be 
  from 
  .87^ 
  to 
  

   4.62^. 
  It 
  probably 
  reaches 
  a 
  far 
  higher 
  amount 
  in 
  bauxites 
  than 
  

   it 
  does 
  in 
  clays, 
  for 
  analyses 
  show 
  a 
  range 
  commonly 
  from 
  3^ 
  to 
  5^. 
  

   In 
  order 
  to 
  determine 
  definitely 
  what 
  the 
  effect 
  of 
  titanium 
  was, 
  

   Seger 
  and 
  Cramer 
  ^ 
  mixed 
  two 
  parts 
  of 
  sample 
  of 
  Zettlitz 
  kaolin 
  

   (which 
  has 
  98.5^ 
  of 
  clay 
  substance) 
  with 
  respectively 
  5;^ 
  and 
  10^ 
  

   of 
  quartz, 
  and 
  two 
  other 
  samples 
  of 
  the 
  kaolin 
  with 
  respectively 
  

   6.65^ 
  and 
  13^ 
  of 
  titanium. 
  These 
  samples 
  were 
  molded 
  into 
  pyra- 
  

   mids 
  which 
  were 
  heated 
  to 
  a 
  temperature 
  above 
  the 
  fusing 
  point 
  of 
  

   iron, 
  with 
  the 
  following 
  results. 
  

  

  1 
  Pure 
  Zettlitz 
  kaolin 
  burned 
  to 
  a 
  white, 
  sharp-edged 
  dense 
  body. 
  

  

  2 
  100 
  pts 
  kaolin 
  and 
  10^ 
  silica 
  burned 
  white. 
  

  

  3 
  " 
  5fo 
  

  

  4 
  , 
  '^ 
  Q.5^ 
  titanium 
  oxid 
  softened 
  on 
  heating 
  

   and 
  showed 
  a 
  blue 
  fracture. 
  

  

  5 
  100 
  pts 
  kaolin 
  and 
  13.3^ 
  titanic 
  oxid 
  fused 
  to 
  a 
  deep 
  blue 
  

   enamel. 
  

  

  It 
  is 
  therefore 
  seen 
  that 
  titanium 
  acts 
  as 
  a 
  flux 
  at 
  lower 
  tem- 
  

   peratures 
  than 
  silica, 
  and 
  it 
  is 
  suggested 
  that 
  the 
  blue 
  color 
  given 
  to 
  

   some 
  stoneware 
  clays 
  by 
  hard 
  firing 
  may 
  not 
  always 
  be 
  due 
  to 
  iron 
  

   oxid. 
  

  

  Organic 
  matter 
  

  

  Organic 
  matter 
  affects 
  not 
  only 
  the 
  color 
  of 
  clay, 
  but 
  also 
  its 
  

   plasticity, 
  absorptive 
  power 
  and 
  tensile 
  streng-th. 
  

  

  It 
  generally 
  consists 
  of 
  finely 
  divided 
  pieces 
  of 
  plant 
  tissue, 
  or 
  

   larger 
  pieces 
  of 
  stems 
  and 
  leaves 
  which 
  settled 
  in 
  the 
  clay 
  during 
  

   its 
  deposition. 
  All 
  surface 
  clays 
  contain 
  plant 
  roots 
  in 
  their 
  upper 
  

   layers, 
  but 
  these 
  do 
  not 
  directly 
  influence 
  the 
  color 
  of 
  the 
  clay. 
  

   Clays 
  colored 
  by 
  organic 
  matter 
  and 
  containing 
  no 
  iron 
  burn 
  

   w^hite, 
  as 
  the 
  plant 
  tissue 
  passes 
  off 
  at 
  bright 
  redness; 
  if 
  such 
  a 
  clay 
  

   however 
  be 
  heated 
  too 
  quickly, 
  before 
  all 
  the 
  organic 
  matter 
  has 
  had 
  

   an 
  opportunity 
  to 
  escape 
  from 
  the 
  interior, 
  the 
  surface 
  becomes 
  

   dense, 
  and 
  it 
  remains 
  dark 
  -colored. 
  

  

  1 
  Seger. 
  Ges. 
  Schrift, 
  p. 
  411. 
  

  

  