﻿CLAYS 
  OF 
  NEW 
  YORK 
  537 
  

  

  ing 
  the 
  insoluble 
  residue 
  (r) 
  from 
  the 
  total 
  analysis, 
  thus 
  ob- 
  

   taining 
  : 
  

  

  Per 
  cent 
  

  

  SiOa 
  17.83 
  

  

  AlA 
  12.21 
  

  

  FeA 
  4.40 
  

  

  CaO 
  36 
  

  

  MgO 
  1.02 
  

  

  5^^^ 
  [ 
  1.20 
  

  

  IS^aaO 
  j 
  

  

  Ignition 
  3 
  . 
  70 
  

  

  If 
  we 
  take 
  the 
  average 
  composition 
  of 
  mica 
  (including 
  muscovite 
  

   and 
  biotite) 
  as: 
  SiO^, 
  50^; 
  ^2^3? 
  32,€; 
  alkalis, 
  10/^; 
  and 
  other 
  

   fluxes, 
  8^, 
  then 
  we 
  have: 
  

  

  Per 
  cent 
  

  

  1.2x3/20= 
  3.84 
  AlA 
  

  

  1.2x5 
  = 
  6.00 
  SiOg 
  

  

  1.2x1= 
  1.20 
  alkalis 
  

  

  .50 
  magnesia 
  

  

  1.2X0.8= 
  ^ 
  Ac^' 
  

  

  .46 
  iron 
  

  

  Substracting 
  column 
  4 
  from 
  3 
  gives 
  us 
  clay 
  substance 
  and 
  ferric 
  

   oxid 
  : 
  

  

  Per 
  cent 
  

  

  SiOa 
  11.83 
  

  

  AI2O3 
  8.37 
  

  

  FeA 
  3.94 
  

  

  CaO 
  36 
  

  

  MgO 
  .52 
  

  

  Ignition 
  3 
  . 
  70 
  

  

  Total 
  28.72 
  

  

  By 
  this 
  operation 
  the 
  clay 
  has 
  been 
  resolved 
  into 
  : 
  

  

  Per 
  cent 
  

  

  Quartz 
  47 
  . 
  23 
  

  

  Feldspar 
  12 
  . 
  80 
  

  

  Mica 
  11 
  . 
  84 
  

  

  Ferric 
  oxide 
  3 
  . 
  94 
  

  

  Clay 
  substance 
  24.78 
  

  

  