﻿CLAYS 
  OF 
  NEW 
  YORK 
  635 
  

  

  •used 
  shall 
  be 
  thoro-aglily 
  free 
  from 
  iron, 
  as 
  in 
  burning, 
  this 
  element 
  

   makes 
  itself 
  very 
  noticeable 
  ; 
  slight 
  specks 
  of 
  it 
  might 
  mar 
  the 
  ware 
  

   sufficiently 
  to 
  make 
  it 
  unsalable. 
  The 
  removal 
  of 
  iron 
  grains 
  is 
  

   accomplished 
  by 
  means 
  of 
  a 
  strong 
  magnet, 
  which 
  in 
  case 
  the 
  clay 
  

   is 
  used 
  in 
  the 
  form 
  of 
  a 
  slip, 
  is 
  suspended 
  in 
  it, 
  or, 
  if 
  powdered 
  

   clay 
  is 
  used 
  the 
  powder 
  is 
  allowed 
  to 
  pass 
  over 
  the 
  poles 
  of 
  the 
  

   magnet; 
  in 
  either 
  case 
  the 
  iron 
  particles 
  are 
  extracted, 
  the 
  magnet 
  

   being 
  cleaned 
  from 
  time 
  to 
  time. 
  

  

  Purification 
  of 
  fluxes 
  and 
  grogs 
  

  

  Many 
  of 
  the 
  materials 
  belonging 
  to 
  either 
  of 
  these 
  two 
  classes 
  

   are 
  often 
  more 
  or 
  less 
  dirty 
  and 
  can 
  be 
  cleaned 
  by 
  washing. 
  If 
  the 
  

   grogs 
  used, 
  however, 
  contain 
  appreciable 
  particles 
  of 
  iron, 
  it 
  is 
  beet 
  

   to 
  remove 
  these 
  by 
  hand 
  picking 
  as 
  far 
  as 
  possible, 
  before 
  the 
  

   material 
  is 
  powdered 
  for 
  use. 
  Feldspar 
  having 
  a 
  red 
  or 
  yellow 
  

   color 
  frequently 
  contains 
  iron 
  oxid, 
  and 
  such 
  should 
  not 
  be 
  used 
  if 
  

   the 
  feldspar 
  is 
  to 
  be 
  used 
  in 
  the 
  manufacture 
  of 
  light 
  colored 
  or 
  

   colorless 
  glazes, 
  while 
  if 
  it 
  is 
  to 
  be 
  used 
  for 
  dark 
  glazes 
  the 
  iron 
  

   oxid 
  contents 
  are 
  of 
  less 
  importance. 
  

  

  Many 
  red 
  feldspars, 
  however, 
  when 
  calcined 
  became 
  pure 
  white, 
  

   showing 
  that 
  the 
  coloration 
  is 
  not 
  due 
  to 
  iron. 
  

  

  