﻿796 
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  state 
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  Comparative 
  compositions 
  of 
  porcelain 
  and 
  white 
  earthenware 
  

  

  Japanese 
  Wegeli 
  porce- 
  Belgian 
  

  

  porcelain 
  lain 
  mix- 
  white 
  earth- 
  

   mixture 
  ture 
  enware 
  mixture 
  

  

  Per 
  cent 
  Per 
  cent 
  Per 
  cent 
  

  

  Claj 
  substance 
  T 
  . 
  49 
  . 
  44 
  81.37 
  58.56 
  

  

  Quartz 
  45.36 
  5.53 
  30.36 
  

  

  Feldspar 
  5.20 
  13.10 
  11.08 
  

  

  Total 
  100 
  . 
  00 
  100 
  . 
  00 
  100 
  . 
  00 
  

  

  The 
  conclusions 
  are 
  that 
  the 
  difference 
  between 
  porcelain 
  and 
  

   white 
  earthenware 
  depends 
  on 
  the 
  temperature 
  at 
  which 
  the 
  mate- 
  

   rial 
  is 
  burned, 
  viz, 
  to 
  vitrification 
  or 
  incipient 
  sintering, 
  and 
  not 
  

   on 
  the 
  composition. 
  

  

  Some 
  porcelains 
  are 
  vitrified 
  at 
  a 
  temperature 
  of 
  only 
  2400° 
  F. 
  

   (Seger's 
  cone 
  9). 
  Examples 
  of 
  this 
  are 
  Soger's 
  porcelain 
  and 
  

   Copenhagen 
  biscuit 
  ware, 
  whose 
  rational 
  compositions 
  are 
  as 
  

   follows 
  : 
  

  

  Compositions 
  of 
  Seger's 
  porcelain 
  and 
  of 
  Copenhagen 
  biscuit 
  ware 
  

  

  vitrifying 
  at 
  2400° 
  F. 
  

  

  Seger 
  Copenhagen 
  

  

  Per 
  cent 
  Ptr 
  cent 
  

  

  Clay 
  substance 
  26 
  32 
  

  

  Quartz 
  45 
  

  

  Feldspar 
  30 
  68 
  

  

  These 
  bodies 
  when 
  burned 
  show 
  a 
  glassy, 
  conchoidal 
  fracture. 
  

   As 
  the 
  feldspar 
  is 
  that 
  part 
  of 
  the 
  porcelain 
  which 
  brings 
  about 
  

   lihe 
  vitrification, 
  we 
  must 
  assume 
  from 
  the 
  Japanese 
  and 
  Wegeli 
  

   porcelain 
  mixtures, 
  given 
  above, 
  that 
  a 
  much 
  higher 
  temperature 
  

   is 
  required 
  to 
  sinter 
  them 
  than 
  the 
  Seger 
  and 
  Copenhagen 
  mixtures. 
  

  

  It 
  is 
  possible 
  to 
  find 
  mixtures 
  showing 
  all 
  grades 
  of 
  transition 
  

   in 
  composition 
  between 
  white 
  earthenware 
  and 
  porcelain. 
  

  

  As 
  to 
  the 
  behavior 
  of 
  easily 
  fusible 
  white 
  earthenware 
  glazes 
  

   and 
  porcelain 
  glazes 
  on 
  these 
  transitional 
  members, 
  Hecht 
  finds 
  

  

  X 
  

  

  