﻿CLAYS 
  OF 
  NEW 
  YORK 
  

  

  673 
  

  

  on 
  the 
  nature 
  of 
  the 
  clay 
  used 
  and 
  the 
  grade 
  of 
  product 
  desired. 
  

   Common 
  bricks 
  for 
  instance 
  may 
  not 
  require 
  a 
  temperature 
  of 
  more 
  

   than 
  1800° 
  F., 
  while 
  othe^ 
  wares 
  may 
  have 
  to 
  be 
  burned 
  at 
  a 
  tem- 
  

   perature 
  of 
  2300° 
  F. 
  or 
  2500° 
  F. 
  

  

  In 
  the 
  burning 
  process 
  a 
  number 
  of 
  different 
  things 
  exert 
  more 
  

   or 
  less 
  influence 
  and 
  consequently 
  must 
  be 
  taken 
  into 
  consideration. 
  

   Among 
  these 
  we 
  may 
  mention 
  the 
  character 
  of 
  the 
  clay, 
  the 
  char- 
  

   acter 
  of 
  the 
  fuel, 
  the 
  type 
  of 
  kiln 
  to 
  be 
  used, 
  the 
  temperature 
  em- 
  

   ployed, 
  the 
  composition 
  of 
  the 
  fire 
  gases, 
  etc. 
  

  

  The 
  detailed 
  changes 
  which 
  the 
  clay 
  undergoes, 
  when 
  burned 
  

   have 
  already 
  been 
  mentioned. 
  

  

  In 
  burning, 
  the 
  wares 
  are 
  piled 
  up 
  in 
  the 
  kiln, 
  as 
  in 
  the 
  case 
  of 
  

   common 
  brick, 
  and 
  front 
  brick, 
  or 
  they 
  may 
  have 
  to 
  be 
  inclosed 
  

   in 
  receptacles 
  to 
  protect 
  them 
  from 
  the 
  action 
  of 
  fire 
  gases, 
  and 
  

   they 
  may 
  sometimes 
  need 
  to 
  be 
  partially 
  inclo^d 
  by 
  means 
  of 
  fire 
  

   brick 
  slabs 
  in 
  order 
  to 
  prevent 
  the 
  exertion 
  of 
  any 
  excessive 
  pressure 
  

   on 
  them, 
  which 
  would 
  cause 
  them 
  to 
  lose 
  their 
  form. 
  

  

  Some 
  clays 
  are 
  burned 
  only 
  to 
  a 
  condition 
  of 
  incipient 
  fusion, 
  

   while 
  others 
  are 
  burned 
  to 
  a 
  stage 
  of 
  vitrification. 
  Common 
  brick 
  

   are 
  an 
  example 
  of 
  the 
  former, 
  paving 
  brick 
  of 
  the 
  latter. 
  

  

  The 
  type 
  of 
  kiln 
  used 
  varies 
  with 
  the 
  product 
  and 
  also 
  with 
  the 
  

   locality, 
  but 
  in 
  every 
  case 
  it 
  is 
  either 
  up-draft 
  or 
  down-draft. 
  

   In 
  the 
  former 
  case 
  the 
  fire 
  passes 
  from 
  the 
  bottom 
  of 
  the 
  kiln 
  up- 
  

   ward 
  through 
  the 
  ware 
  and 
  out 
  at 
  the 
  top, 
  escaping 
  either 
  at 
  many 
  

   points 
  or 
  through 
  a 
  chimney. 
  In 
  the 
  latter 
  case 
  the 
  fire 
  is 
  con- 
  

   ducted 
  to 
  the 
  top 
  of 
  the 
  kiln 
  first 
  by 
  means 
  of 
  ^^ 
  pockets 
  " 
  or 
  ^' 
  bags 
  '' 
  

   on 
  the 
  interior 
  wall, 
  passes 
  downwai'd 
  through 
  the 
  ware 
  and 
  then 
  

   out 
  through 
  flues 
  in 
  the 
  floor 
  of 
  the 
  kiln 
  to 
  the 
  stack. 
  All 
  kilns 
  

   are 
  also 
  either 
  continuous 
  or 
  intermittent 
  in 
  their 
  action. 
  In 
  the 
  

   former 
  the 
  heat 
  from 
  the 
  cooling 
  chamber 
  is 
  conducted 
  through 
  

   those 
  which 
  have 
  not 
  yet 
  been 
  burned, 
  and 
  is 
  used 
  to 
  heat 
  them 
  

   up. 
  Both 
  the 
  up-draft 
  and 
  down-draft 
  kilns 
  are 
  either 
  rectr 
  

   angular 
  or 
  round 
  in 
  form, 
  the 
  former 
  having 
  a 
  larger 
  capacity. 
  

   The 
  different 
  types 
  of 
  kiln 
  are 
  mentioned 
  in 
  more 
  detail 
  farther 
  on. 
  

  

  