﻿CLAYS 
  OF 
  NEW 
  YORK 
  

  

  787 
  

  

  should 
  also 
  burn 
  dense 
  at 
  so 
  low 
  a 
  temperature 
  that 
  when 
  grog 
  is 
  

   added 
  the 
  heat 
  will 
  not 
  need 
  to 
  be 
  raised 
  too 
  much 
  in 
  getting 
  the 
  

   required 
  density. 
  The 
  addition 
  of 
  grog 
  will 
  raise 
  this 
  point 
  to 
  an 
  

   extent 
  depending 
  on 
  the 
  amount 
  added. 
  Thus 
  the 
  temperature 
  

   of 
  densification 
  of 
  a 
  mixture 
  given 
  below 
  is 
  the 
  same 
  as 
  cone 
  5, 
  

   while 
  that 
  of 
  the 
  clay 
  is 
  cone 
  1. 
  If 
  now 
  a 
  clay 
  is 
  used 
  as 
  binding 
  

   material 
  which 
  sinters 
  at 
  high 
  temperature, 
  the 
  temperature 
  at 
  

   which 
  the 
  mixture 
  becomes 
  deifse 
  will 
  be 
  so 
  high 
  as 
  to 
  make 
  its 
  

   burning 
  difficult. 
  

  

  In 
  judging 
  the 
  tensile 
  strength, 
  the 
  size 
  of 
  the 
  grain 
  of 
  grog 
  must 
  

   be 
  considered, 
  as 
  also 
  the 
  relation 
  in 
  which 
  the 
  different 
  sized 
  

   grains 
  are 
  mixed, 
  but 
  no 
  fixed 
  rule 
  can 
  be 
  laid 
  down 
  for 
  the 
  last 
  

   point. 
  In 
  the 
  grinding 
  of 
  grog 
  both 
  a 
  powdery 
  product 
  and 
  angu- 
  

   lar 
  grains 
  are 
  obtained, 
  and 
  practice 
  has 
  shown 
  that 
  it 
  is 
  desirable 
  

   to 
  add 
  both 
  of 
  these 
  to 
  the 
  clay, 
  since, 
  if 
  the 
  grains 
  alone 
  were 
  

   added, 
  the 
  mixture 
  would 
  show 
  a 
  tendency 
  to 
  crack. 
  

  

  The 
  following 
  mixture 
  is 
  one 
  given 
  by 
  E. 
  Cramer 
  {Thonindus- 
  

   trie 
  zeitung. 
  1897. 
  p. 
  47) 
  : 
  100 
  parts 
  by 
  weight 
  of 
  clay 
  and 
  120 
  

   parte 
  grog. 
  On 
  a 
  sieve 
  of 
  10 
  meshe© 
  to 
  the 
  square 
  cm 
  the 
  grog 
  

   left 
  no 
  residue, 
  but 
  20^ 
  remained 
  on 
  a 
  60 
  mesh 
  sieve, 
  and 
  12^ 
  on 
  

   oaie 
  of 
  120 
  mesh, 
  24^ 
  on 
  a 
  900 
  mesh, 
  30^ 
  on 
  a 
  5000 
  mesh, 
  and 
  14!^ 
  

   went 
  through. 
  

  

  The 
  investigation 
  of 
  glass-pot 
  clay 
  is 
  confined 
  to 
  a 
  determination 
  

   of 
  plasticity, 
  shrinkage, 
  temperature 
  at 
  which 
  ,the 
  clay 
  becomes 
  

   dense, 
  fusion 
  point, 
  and 
  chemical 
  composition. 
  

  

  Clays 
  fulfilling 
  all 
  these 
  conditions 
  satisfactorily 
  are 
  rare 
  in 
  

   the 
  United 
  States. 
  They 
  are 
  thus 
  far 
  known 
  in 
  only 
  a 
  few 
  regions, 
  

   being 
  found 
  in 
  Missouri 
  and 
  in 
  small 
  quantities 
  in 
  Ohio 
  and 
  Penn- 
  

   sylvania. 
  In 
  Europe 
  they 
  occur 
  at 
  several 
  localities, 
  in 
  Germany, 
  

   Belgium, 
  Bohemia, 
  Russia, 
  England, 
  France, 
  and 
  Scotland. 
  

  

  Large 
  quantities 
  of 
  the 
  German 
  and 
  Belgian 
  glass 
  pot 
  clays 
  are 
  

   annually 
  exported 
  to 
  the 
  United 
  States^. 
  

  

  1 
  For 
  information 
  concerning 
  the 
  properties 
  of 
  some 
  of 
  these 
  European* 
  

   glass 
  pot 
  clays, 
  see 
  Report 
  on 
  kaolins 
  and 
  fire 
  claya 
  of 
  Europe. 
  ]9th 
  arin, 
  rep't 
  

   U. 
  S. 
  geol. 
  sur. 
  pt 
  6. 
  

  

  