﻿I 
  

  

  CLAYS 
  OF 
  NEW 
  YORK 
  639 
  

  

  Tlie 
  following 
  gives 
  the 
  maximiim, 
  minimum 
  and 
  average 
  per- 
  

   centage 
  of 
  the 
  different 
  constituents 
  in 
  the 
  brick 
  clay 
  analyses 
  

   given 
  in 
  the 
  tables 
  at 
  the 
  end 
  of 
  the 
  report. 
  

  

  Range 
  Average 
  

  

  Silica 
  34.35 
  —90.877 
  49.27^ 
  

  

  Alumina 
  22.14 
  —44.00 
  22.774^ 
  

  

  Ferric 
  oxid 
  126 
  — 
  33 
  . 
  12 
  6 
  . 
  311^ 
  

  

  lime 
  024 
  — 
  23.20 
  2.017^ 
  

  

  Magnesia 
  02—11.03 
  2.66,'^ 
  

  

  Alkalis 
  17 
  —i:..Z2 
  2.768^ 
  

  

  "Water 
  05 
  —13.60 
  5.749^ 
  

  

  Moisture 
  17 
  — 
  9.64 
  2.502^ 
  

  

  Clay 
  for 
  pressed 
  brick. 
  In 
  addition 
  to 
  the 
  characters 
  mentioned 
  

   under 
  common 
  brick 
  clays, 
  it 
  is 
  highly 
  necessary 
  that 
  the 
  materials 
  

   used 
  should 
  bum 
  to 
  a 
  uniform 
  color. 
  They 
  should 
  be 
  as 
  free 
  as 
  

   possible 
  from 
  soluble 
  salts, 
  specially 
  if 
  the 
  product 
  is 
  not 
  vitrified. 
  

  

  Many 
  different 
  grades 
  of 
  clay 
  are 
  utilized, 
  but 
  chief 
  among 
  them 
  

   may 
  be 
  mentioned 
  white 
  burning 
  clays, 
  buff 
  burning 
  clays 
  (either 
  

   calcareous 
  or 
  semi-refractory), 
  red 
  burning 
  clays, 
  commonly 
  high 
  in 
  

   iron 
  oxid. 
  

  

  Semi-refractory, 
  or 
  refractory 
  clays, 
  form 
  an 
  important 
  source 
  

   of 
  material 
  for 
  making 
  front 
  brick, 
  not 
  only 
  on 
  account 
  of 
  the 
  buff 
  

   color 
  to 
  which 
  they 
  burn, 
  but 
  also 
  because 
  this 
  color 
  permits 
  the 
  

   admixture 
  of 
  manganese 
  for 
  the 
  production 
  of 
  mottled 
  and 
  speckled 
  

   effects 
  and 
  various 
  shades 
  producible 
  by 
  the 
  addition 
  of 
  the 
  same 
  

   material 
  in 
  powdered 
  form. 
  

  

  The 
  shrinkage 
  of 
  the 
  clay 
  in 
  burning 
  should 
  be 
  regular 
  and 
  

   even, 
  in 
  order 
  that 
  the 
  finished 
  bricks 
  may 
  all 
  be 
  very 
  nearly 
  of 
  the 
  

   same 
  size. 
  

  

  Burning 
  of 
  brick 
  clay 
  

  

  Brick 
  clays 
  when 
  burned 
  exhibit 
  a 
  variety 
  of 
  shades 
  and 
  colors 
  

   whose 
  existence 
  is 
  influenced 
  by 
  several 
  causes, 
  such 
  as 
  the 
  amount 
  

   of 
  ferric 
  oxid 
  in 
  a 
  clay, 
  the 
  percentage 
  of 
  other 
  constituents 
  as- 
  

  

  