﻿I 
  

  

  CLAYS 
  OF 
  NEW 
  YORK 
  Y45 
  

  

  water 
  was 
  required 
  to 
  work 
  it 
  up. 
  The 
  air 
  shrinkage 
  was 
  4^. 
  Up 
  

   to 
  cone 
  .03 
  it 
  was 
  10^. 
  It 
  vitrified 
  at 
  2 
  and 
  became 
  viscous 
  at 
  5. 
  

   The 
  tensile 
  strength 
  was 
  from 
  60 
  to 
  70 
  pounds 
  a 
  square 
  inch. 
  

  

  Manufacture 
  of 
  paving 
  hrich 
  

  

  Shale 
  is 
  used 
  more 
  than 
  clay 
  in 
  the 
  manufacture 
  of 
  paving 
  brick. 
  

   It 
  has 
  to 
  be 
  prepared 
  first 
  by 
  crushing 
  in 
  a 
  dry 
  pan, 
  then 
  screened. 
  

   This 
  screened 
  clay 
  is 
  mixed 
  with 
  water 
  and 
  tempered 
  either 
  in 
  a 
  

   pug 
  mill 
  or 
  in 
  a 
  wet 
  pan. 
  (For 
  description 
  see 
  " 
  Manufacture 
  of 
  

   common 
  brick 
  ", 
  p. 
  653) 
  

  

  Paving 
  brick 
  are 
  commonly 
  molded 
  in 
  an 
  auger 
  machine; 
  they 
  

   are 
  either 
  end-cut 
  or 
  side-cut. 
  At 
  a 
  few 
  factories 
  the 
  soft 
  mud 
  

   method 
  is 
  used, 
  but 
  in 
  this 
  state 
  it 
  is 
  only 
  employed 
  at 
  Syracuse. 
  

   Repressing 
  the 
  green 
  brick 
  is 
  commonly 
  practised, 
  but 
  there 
  is 
  a 
  

   difference 
  of 
  opinion* 
  as 
  to 
  whether 
  it 
  improves 
  the 
  quality 
  of 
  the 
  

   brick, 
  though 
  the 
  experiments 
  given 
  on 
  the 
  following 
  pages 
  tend 
  to 
  

   indicate 
  that 
  the 
  end-cut 
  repressed 
  brick 
  are 
  the 
  strongest, 
  while 
  

   still 
  more 
  recent 
  tests 
  somewhat 
  disfavor 
  this 
  view. 
  

  

  The 
  green 
  brick 
  are 
  usually 
  piled 
  on 
  cars 
  and 
  dried 
  in 
  tunnels. 
  

  

  Paving 
  brick 
  should 
  be 
  burned 
  in 
  down-draft 
  kilns, 
  as 
  they 
  give 
  

   better 
  results 
  than 
  the 
  up-draft 
  kilns, 
  and 
  there 
  is 
  no 
  loss 
  from 
  

   crushed, 
  overbumed 
  brick. 
  

  

  The 
  type 
  of 
  kiln 
  used 
  in 
  this 
  state 
  is 
  either 
  the 
  rectangular 
  down- 
  

   draft 
  kiln 
  or 
  a 
  continuous 
  one. 
  The 
  latter 
  is 
  extending 
  in 
  favor, 
  

   as 
  it 
  is 
  the 
  more 
  economical 
  and 
  yields 
  good 
  results. 
  Circular 
  kilns 
  

   are 
  but 
  little 
  used 
  in 
  this 
  state 
  for 
  burning 
  paving 
  brick. 
  

  

  Tests 
  of 
  paving 
  hrich 
  

   For 
  a 
  long 
  period 
  there 
  has 
  been 
  some 
  difference 
  of 
  opinion 
  as 
  to 
  

   what 
  constitutes 
  the 
  qualities 
  requisite 
  for 
  a 
  paving 
  brick. 
  Engi- 
  

   neers 
  have 
  frequently 
  laid 
  considerable 
  stress 
  on 
  the 
  crushing 
  test 
  

   and 
  the 
  color. 
  The 
  latter 
  is 
  of 
  no 
  value 
  as 
  a 
  guide; 
  the 
  former 
  be- 
  

   yond 
  certain 
  limits 
  is 
  to 
  be 
  looked 
  on 
  in 
  the 
  same 
  way. 
  With 
  a 
  view, 
  

   therefore, 
  to 
  determine 
  what 
  the 
  requisite 
  qualifications 
  of 
  a 
  paving 
  

  

  