﻿CLAYS 
  OF 
  XEW 
  YORK 
  793 
  

  

  Yellow 
  ware 
  and 
  Rockingham 
  ware. 
  These 
  differ 
  from 
  stoneware 
  

   in 
  that 
  the 
  body 
  is 
  burned. 
  fii^t, 
  then 
  glazed 
  and 
  burned 
  again. 
  It 
  

   agrees 
  with 
  stoneware 
  in 
  being 
  made 
  from 
  natural 
  clays, 
  and 
  with 
  

   white 
  earthenware, 
  or 
  porcelain, 
  in 
  being 
  burned 
  twice. 
  

  

  In 
  yellow 
  ware 
  the 
  body 
  is 
  covered 
  with 
  a 
  transparent, 
  easily 
  

   fusible 
  glaze, 
  while 
  in 
  Rockingham 
  ware 
  the 
  glaze 
  is 
  colored 
  brown 
  

   or 
  black 
  by 
  the 
  addition 
  of 
  manganese. 
  

  

  C. 
  C. 
  ware, 
  white 
  granite. 
  These 
  are 
  made 
  of 
  high 
  gTade 
  clays, 
  

   but 
  not 
  the 
  best 
  obtainable, 
  with 
  other 
  materials. 
  The 
  mixture 
  

   usually 
  consists 
  of 
  kaolin 
  to 
  form 
  the 
  body, 
  ball 
  clay 
  for 
  plasticity, 
  

   silica 
  to 
  prevent 
  excessive 
  shrinkage, 
  and 
  feldspar 
  to 
  serve 
  as 
  a 
  flux. 
  

  

  C. 
  C. 
  ware 
  differs 
  from 
  china 
  or 
  porcelain 
  in 
  the 
  quality 
  of 
  the 
  

   materials 
  used, 
  the 
  clays 
  employed 
  having 
  enough 
  iron 
  to 
  give 
  a 
  

   slight 
  off 
  color 
  to 
  the 
  ^^are. 
  Attempts 
  are 
  made 
  to 
  counteract 
  this 
  

   by 
  introducing 
  coloring 
  material 
  into 
  the 
  glaze. 
  

  

  In 
  white 
  granite 
  or 
  ironstone 
  china 
  the 
  best 
  materials 
  obtainable 
  

   are 
  used, 
  but 
  the 
  body 
  is 
  not 
  burned 
  to 
  vitrification, 
  and 
  differs 
  in 
  

   that 
  respect 
  from 
  porcelain. 
  In 
  fact 
  white 
  granite 
  bears 
  the 
  same 
  

   relation 
  to 
  porcelain 
  that 
  earthenware 
  does 
  to 
  stoneware. 
  A 
  very 
  

   slight 
  amount 
  of 
  iron 
  will 
  tend 
  to 
  produce 
  a 
  yellowish 
  tint, 
  which 
  is 
  

   neutralized 
  by 
  adding 
  a 
  small 
  amount 
  of 
  cobalt 
  oxid, 
  that 
  produces 
  

   a 
  greenish 
  hue 
  far 
  less 
  noticeable. 
  

  

  The 
  kaolins 
  and 
  sometimes 
  the 
  ball 
  clays 
  have 
  to 
  be 
  purified 
  by 
  

   s. 
  washing 
  process; 
  for 
  the 
  percentage 
  of 
  iron 
  oxid 
  which 
  a 
  kaolin 
  

   contains 
  should 
  be 
  less 
  than 
  1^. 
  Even 
  though 
  the 
  clay 
  alone 
  may 
  

   not 
  show 
  any 
  off 
  tint 
  when 
  burned, 
  the 
  presence 
  of 
  a 
  coating 
  of 
  

   glaze 
  is 
  sure 
  to 
  bring 
  it 
  out, 
  if 
  the 
  iron 
  is 
  present. 
  The 
  kaolins 
  used 
  

   in 
  this 
  country 
  are 
  obtained 
  mostly 
  from 
  England, 
  Xorth 
  Carolina, 
  

   and 
  Georgia, 
  while 
  the 
  ball 
  clays 
  come 
  from 
  Xew 
  Jersey, 
  Florida, 
  

   Kentucky 
  and 
  Missouri. 
  

  

  Quartz 
  and 
  feldspar 
  are 
  obtained 
  from 
  a 
  number 
  of 
  localities, 
  

   some 
  of 
  them 
  in 
  !N'ew 
  York. 
  

  

  