﻿CLAYS 
  OF 
  IsEW 
  YOEK 
  553 
  

  

  ^]^ 
  = 
  flnm 
  of 
  nondetrimentals, 
  or 
  silica, 
  alumina, 
  titanic 
  acid, 
  

   water, 
  moisture, 
  and 
  carbonic 
  acid 
  

  

  GD 
  = 
  sum 
  of 
  detrimental 
  impurities, 
  or 
  tke 
  iron, 
  lime, 
  magnesia, 
  

   alkalis, 
  sulfuric 
  acid, 
  sulfur, 
  etc. 
  

  

  D^= 
  sum 
  of 
  alkalies 
  which 
  Wheeler 
  supposes 
  to 
  have 
  tmce 
  the 
  

   flu:sing 
  value 
  

  

  C 
  = 
  1, 
  when 
  clay 
  is 
  coarse-grained 
  and 
  specific 
  gravity 
  exceeds 
  

   2.25 
  

  

  = 
  2, 
  when 
  clay 
  is 
  coarse-grained 
  and 
  specific 
  gravity 
  from 
  

   2-2.25 
  

  

  0=3, 
  when 
  specific 
  gravity 
  ranges 
  from 
  1.75-2 
  

  

  = 
  2, 
  when 
  clay 
  is 
  fine-grained 
  and 
  specific 
  gravity 
  above 
  2-25 
  

  

  = 
  3, 
  when 
  clay 
  is 
  fine-grained 
  and 
  specific 
  gravity 
  from 
  2-2.25 
  

  

  = 
  4, 
  when 
  clay 
  is 
  fine-grained 
  and 
  specific 
  gravity 
  from 
  1.75-2 
  

  

  This 
  formula 
  gives 
  better, 
  but 
  still 
  not 
  regular 
  results. 
  The 
  in- 
  

   sertion 
  of 
  a 
  term 
  to 
  account 
  for 
  fineness 
  of 
  grain 
  is 
  perfectly 
  

   rational, 
  but 
  the 
  specific 
  gravity 
  is 
  dependent 
  on 
  the 
  mineral 
  com- 
  

   position 
  of 
  the 
  clay 
  and 
  therefore 
  indirectly 
  connected 
  with 
  the 
  

   chemical 
  constitution. 
  

  

  Determination 
  of 
  fusibility. 
  The 
  temperature 
  at 
  which 
  a 
  clay 
  

   fuses 
  is 
  determined 
  either 
  by 
  means 
  of 
  test 
  pieces 
  of 
  known 
  com- 
  

   position, 
  or 
  by 
  some 
  form 
  of 
  apparatus 
  or 
  mechanical 
  pyrometer 
  

   whose 
  principle 
  depends 
  on 
  the 
  expansion 
  of 
  gases 
  or 
  solids, 
  thermo- 
  

   electricity, 
  spectro-photometry, 
  etc. 
  

  

  When 
  test 
  pieces 
  are 
  used, 
  there 
  are 
  two 
  methods 
  for 
  determining 
  

   the 
  fusibility 
  of 
  a 
  clay, 
  the 
  direct 
  and 
  the 
  indirect. 
  

  

  The 
  direct 
  method 
  is 
  that 
  of 
  Soger, 
  who 
  devised 
  the 
  test 
  pieces 
  

  

  kno\\Ti 
  as 
  " 
  Seger 
  cones 
  ". 
  

  

  These 
  consist 
  of 
  a 
  series 
  of 
  mixtures 
  of 
  clay 
  with 
  fluxes, 
  so 
  

  

  graded 
  that 
  they 
  represent 
  a 
  series 
  of 
  fusion 
  points, 
  each 
  being 
  but 
  

  

  a 
  few 
  degrees 
  higher 
  than 
  the 
  one 
  next 
  to 
  it. 
  The 
  materials 
  used 
  

  

  in 
  making 
  them 
  are 
  such 
  as 
  would 
  have 
  a 
  constant 
  composition, 
  and 
  

  

  consist 
  of 
  washed 
  Zettlitz 
  kaolin, 
  Rorstrand 
  feldspar, 
  !N"orwegian 
  

  

  quartz, 
  Oarrara 
  marble, 
  and 
  pure 
  ferric 
  oxid. 
  

  

  