﻿CLAYS 
  OF 
  NEW 
  YORK 
  739 
  

  

  sectional 
  roofs 
  which 
  are 
  hinged 
  and 
  can 
  be 
  lifted 
  by 
  a 
  lever 
  for 
  the 
  

   purpose 
  of 
  admitting 
  more 
  sunlight. 
  The 
  bricks 
  are 
  burnt 
  with 
  

   wood 
  in 
  clamps; 
  the 
  product 
  is 
  shipped 
  to 
  various 
  points 
  on 
  Long 
  

   Island. 
  

  

  Below 
  is 
  given 
  an 
  analysis 
  of 
  the 
  lower 
  clay. 
  

  

  Silica 
  62.39 
  

  

  Alumina 
  23.60 
  

  

  Oxid 
  of 
  iron 
  3 
  . 
  39 
  

  

  Lime 
  TO 
  

  

  Magnesia 
  10 
  

  

  Alkalis 
  5.89 
  

  

  96.07 
  

  

  The 
  physical 
  properties 
  of 
  the 
  two 
  clays 
  from 
  Meyers's 
  bank 
  are 
  

   as 
  follows 
  : 
  

  

  Upper 
  clay. 
  "While 
  this 
  differs 
  from 
  the 
  lower 
  clay 
  in 
  color, 
  

   because 
  of 
  the 
  higher 
  oxidation 
  of 
  the 
  iron 
  oxid, 
  at 
  the 
  same 
  time 
  it 
  

   is 
  more 
  sandy, 
  containing 
  a 
  large 
  amount 
  of 
  very 
  fine 
  sand 
  and 
  

   mica 
  scales. 
  It 
  is 
  quite 
  plastic 
  and 
  tough, 
  but 
  not 
  very 
  tenacious, 
  

   as 
  shown 
  by 
  its 
  low 
  tensile 
  strength, 
  which 
  ranges 
  from 
  20 
  to 
  25 
  

   pounds 
  a 
  square 
  inch. 
  It 
  took 
  34.70^ 
  of 
  water 
  to 
  work 
  it 
  up; 
  the 
  

   bricklets 
  showed 
  an 
  air 
  shrinkage 
  of 
  6^. 
  At 
  cone 
  .08 
  the 
  clay 
  burns 
  

   bright, 
  but 
  not 
  dark 
  red, 
  with 
  a 
  total 
  shrinkage 
  of 
  7^. 
  Incipient 
  

   fusion 
  occurred 
  at 
  cone 
  .05 
  with 
  a 
  total 
  shrinkage 
  of 
  10^. 
  The 
  clay 
  

   had 
  a 
  shrinkage 
  of 
  14^ 
  when 
  vitrification 
  began 
  at 
  cone 
  1. 
  It 
  be- 
  

   came 
  viscous 
  at 
  cone 
  4. 
  The 
  soluble 
  salts 
  amounted 
  to 
  .14^. 
  

  

  Bottom 
  clay. 
  This 
  is 
  more 
  plastic 
  and 
  slightly 
  more 
  tenacious 
  

   than 
  the 
  top 
  clay, 
  but 
  other^dse 
  does 
  not 
  differ 
  from 
  it 
  very 
  much. 
  

   It 
  absorbed 
  28^ 
  of 
  water 
  in 
  tempering 
  — 
  the 
  air-dried 
  bri- 
  

   quettes 
  had 
  a 
  tensile 
  strength 
  ranging 
  from 
  30 
  to 
  40 
  pounds 
  a 
  square 
  

   inch. 
  The 
  air 
  shrinkage 
  was 
  8^. 
  At 
  cone 
  .08 
  it 
  amounted 
  to 
  8^^, 
  

   at 
  cone 
  .05 
  to 
  10^. 
  Incipient 
  fusion 
  occurred 
  at 
  cone 
  .04, 
  vitrifica- 
  

  

  