﻿536 
  

  

  KEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Analysis 
  of 
  fire 
  clay 
  from 
  Ohio 
  

  

  

  1 
  

  

  Total 
  

   analysis 
  

  

  2 
  

  

  Insoluble 
  

   InHgSO^ 
  

  

  SiOo 
  

  

  Per 
  cent 
  

  

  73.21 
  

   14.56 
  

   4.79 
  

   .51 
  

   1.07 
  

   1.75 
  

   1.16 
  

   3.70 
  

  

  Per 
  cent 
  

  

  55.38 
  

  

  ALO, 
  

  

  2.35 
  

  

  FeaOs 
  

  

  .39 
  

  

  CaO 
  

  

  .15 
  

  

  MgO 
  

  

  K2O 
  

  

  .05 
  

   1.71 
  

  

  NagO 
  

  

  

  Ignition 
  

  

  

  Total 
  

  

  100.75 
  

  

  60.03 
  

  

  The 
  insoluble 
  residue 
  consists 
  of 
  quartz, 
  feldspar, 
  and 
  perhaps 
  

   traces 
  of 
  silicate 
  minerals 
  approacliing 
  feldspar 
  in 
  composition. 
  

   In 
  orthoclase 
  (the 
  common 
  feldspar) 
  the 
  amount 
  of 
  silica 
  is 
  about 
  

   3.51 
  times 
  that 
  of 
  alumina. 
  Therefore, 
  the 
  alumina 
  of 
  the 
  insolu- 
  

   ble 
  portion 
  multiplied 
  by 
  3.51 
  gives 
  the 
  silica 
  of 
  the 
  feldspar, 
  

   which, 
  subtracted 
  from 
  the 
  total 
  silica 
  of 
  residue, 
  leaves 
  the 
  silica 
  

   present 
  as 
  quarts. 
  Thus, 
  in 
  the 
  column 
  2, 
  above, 
  we 
  have 
  : 
  

  

  Silica 
  

   Per 
  cent 
  

  

  2.35x3.51== 
  8.25 
  

  

  Alumina 
  2.35 
  

  

  Fluxes 
  2.20 
  

  

  Per 
  cent 
  feldspar 
  12.80 
  

  

  Subtracting 
  this 
  from 
  the 
  total 
  insoluble 
  residue 
  gives 
  the 
  

   amount 
  of 
  quartz. 
  

  

  As 
  {he 
  clay 
  substance, 
  mica 
  and 
  ferric 
  oxid 
  are 
  the 
  soluble 
  

   portion 
  of 
  the 
  clay, 
  their 
  total 
  composition 
  is 
  obtained 
  by 
  subtract- 
  

  

  