﻿CLAYS 
  OF 
  NEW 
  YORK 
  523 
  

  

  sulfate. 
  This 
  takes 
  up 
  water 
  in 
  chemical 
  combination 
  and 
  forais 
  

   gypsum. 
  

  

  In 
  many 
  instances 
  the 
  presence 
  of 
  gypsum 
  can 
  be 
  instantly 
  de- 
  

   tected 
  by 
  the 
  large 
  transparent 
  crystals 
  scattered 
  through 
  the 
  clay; 
  

   at 
  other 
  times 
  it 
  is 
  found 
  in 
  the 
  form 
  of 
  parallel 
  fibres 
  filling 
  cracks 
  

   or 
  cavities 
  in 
  the 
  clay. 
  So 
  far 
  as 
  the 
  ^^T-iter 
  is 
  aware, 
  only 
  the 
  

   former 
  type 
  has 
  been 
  found 
  in 
  the 
  ISTew 
  York 
  clays. 
  Gypsum 
  may 
  

   serve 
  as 
  a 
  flux, 
  but 
  at 
  the 
  same 
  time 
  it 
  may 
  do 
  considerable 
  damage 
  

   in 
  the 
  burning 
  by 
  the 
  liberation 
  of 
  sulfuric 
  acid, 
  which 
  in 
  its 
  efforts 
  

   to 
  escape 
  may 
  cause 
  blisters 
  on 
  the 
  surface 
  of 
  the 
  ware. 
  Lime 
  may 
  

   be 
  introduced 
  into 
  a 
  clay 
  by 
  absorption, 
  where 
  a 
  clay 
  deposit 
  rests 
  on 
  

   a 
  limestone 
  or 
  marl 
  formation, 
  the 
  clay 
  absorbing 
  waters 
  from 
  below 
  

   that 
  contain 
  lime 
  in 
  solution, 
  which 
  the 
  clay 
  tends 
  to 
  separate. 
  

  

  AH 
  clays 
  do 
  not 
  contain 
  lime, 
  and 
  indeed 
  it 
  sometimes 
  happens 
  

   that 
  the 
  clays 
  over 
  very 
  large 
  areas 
  are 
  singularly 
  free 
  from 
  it, 
  

   while 
  in 
  other 
  regions 
  the 
  opposite 
  may 
  be 
  true. 
  The 
  clays 
  in 
  many 
  

   parts 
  of 
  Alabama 
  are 
  remarkably 
  low 
  in 
  lime. 
  Those 
  underlying 
  

   the 
  region 
  around 
  Chicago', 
  and 
  again 
  around 
  Buffalo 
  have 
  an 
  ap- 
  

   preciable 
  am^ount 
  of 
  it. 
  This 
  material 
  has 
  been 
  one 
  of 
  the 
  chief 
  

   causes 
  in 
  restricting 
  the 
  utilization 
  of 
  the 
  Hudson 
  valley 
  clays, 
  

   which 
  for 
  combining 
  extent, 
  location 
  and 
  accessibility 
  are 
  not 
  sur- 
  

   passed 
  by 
  any 
  other 
  deposit. 
  

  

  The 
  range 
  of 
  lime 
  in 
  different 
  clays 
  Is 
  given 
  below. 
  

  

  Kind 
  of 
  clay 
  Min. 
  Max. 
  Aver. 
  

  

  Brick 
  clay 
  

  

  Pottery 
  clay 
  

  

  Fire 
  clay 
  

  

  Kaolin 
  

  

  Magnesia 
  

   Magnesia 
  rarely 
  occurs 
  in 
  clays 
  in 
  the 
  same 
  quantity 
  as 
  lime, 
  and 
  

   in 
  fact 
  seldom 
  exceeds 
  2^. 
  The 
  same 
  classes 
  of 
  compounds 
  may 
  fur- 
  

   nish 
  it 
  as 
  furnish 
  lime, 
  viz, 
  silicates, 
  carbonates 
  and 
  sulfates. 
  The 
  

  

  .024 
  

  

  23.20 
  

  

  2.017 
  

  

  .011 
  

  

  9.90 
  

  

  1.098 
  

  

  .03 
  

  

  15.27 
  

  

  .655 
  

  

  tr 
  

  

  2.58 
  

  

  .47 
  

  

  