﻿Y60 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  one 
  of 
  those 
  Tised 
  by 
  tlie 
  New 
  York 
  arcliitectural 
  terra 
  cotta 
  co. 
  

   It 
  possesses 
  the 
  advantages 
  of 
  being 
  very 
  plastic, 
  burning 
  to 
  a 
  

   deep 
  red, 
  with 
  a 
  very 
  dense 
  body 
  at 
  a 
  comparatively 
  low 
  tempera- 
  

   ture. 
  It 
  took 
  33.70^ 
  of 
  water 
  to 
  work 
  it 
  up. 
  The 
  air 
  shrinkage 
  

   was 
  6^, 
  and 
  at 
  .06, 
  9.5^. 
  Incipient 
  vitrification 
  began 
  at 
  .03, 
  

   with 
  12^ 
  shrinkage; 
  complete 
  vitrification 
  was 
  reached 
  at 
  4. 
  

   Viscosity 
  at 
  B. 
  The 
  percentage 
  of 
  soluble 
  salts 
  contained 
  in 
  the 
  

   clay 
  was 
  .25^. 
  The 
  tensile 
  strength 
  showed 
  a 
  minimum 
  of 
  75 
  

   pounds 
  and 
  a 
  maximum 
  of 
  90 
  to 
  the 
  square 
  inch. 
  The 
  clay 
  slakes 
  

   quite 
  rapidly 
  in 
  water. 
  

   Its 
  composition 
  is 
  

  

  Silica 
  67.00 
  

  

  Alumina 
  29 
  . 
  20 
  

  

  Ferric 
  oxid 
  4.80 
  

  

  lime 
  .65 
  

  

  Magnesia 
  .31 
  

  

  Alkalis 
  1.80 
  

  

  Water 
  6 
  . 
  10 
  

  

  Total 
  

  

  Olens 
  Falls. 
  Two 
  varieties 
  of 
  clay 
  occur 
  here 
  in 
  the 
  pits 
  of 
  the 
  

   'Glens 
  Falls 
  terra 
  cotta 
  co., 
  the 
  upper 
  being 
  red, 
  and 
  the 
  lower 
  

   bluish 
  gray. 
  The 
  composition 
  is 
  indicated 
  by 
  the 
  following 
  

   analyses. 
  

  

  ^i^if 
  Red. 
  

  

  gray 
  

  

  Silica 
  48.35 
  57.46 
  

  

  Alumina 
  11.33 
  21.15 
  

  

  Oxid 
  of 
  iron 
  4.02 
  5.52 
  

  

  Lime 
  15.38 
  3.65 
  

  

  Magnesia 
  3.17 
  1.50 
  

  

  Organic 
  matter 
  1 
  . 
  18 
  .... 
  

  

  Alkalis 
  6 
  . 
  05 
  4.72 
  

  

  89.48 
  94.00 
  

  

  