﻿668 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  the 
  frost. 
  Owing 
  to 
  their 
  greater 
  density, 
  dry 
  press 
  brick 
  have 
  to 
  

   be 
  burned 
  more 
  slowly 
  than 
  those 
  made 
  by 
  other 
  methods. 
  

  

  The 
  stiff 
  mnd 
  process 
  is 
  adaptable 
  mainly, 
  if 
  the 
  best 
  results 
  are 
  

   desired, 
  to 
  clays 
  of 
  moderate 
  or 
  good 
  plasticity, 
  which 
  will 
  dry 
  in 
  

   a 
  reasonable 
  time. 
  As 
  the 
  clay 
  in 
  flowing 
  through 
  the 
  die 
  requires 
  

   much 
  tenacity 
  to 
  escape 
  tear, 
  very 
  siliceous, 
  clays 
  are 
  not 
  desirable, 
  

   and 
  on 
  the 
  other 
  hand 
  very 
  plastic 
  ones 
  tend 
  to 
  develop 
  laminations 
  

   in 
  the 
  brick. 
  The 
  capacity 
  of 
  the 
  stiff 
  mud 
  machines 
  is 
  very 
  great 
  

   and 
  their 
  use 
  is 
  increasing, 
  though 
  it 
  is 
  already 
  extensive. 
  

  

  Repressing- 
  of 
  bricks 
  

  

  Paving 
  brick 
  and 
  front 
  brick 
  are 
  sometimes 
  repressed, 
  the 
  object 
  

   being 
  to 
  give 
  sharper 
  edges 
  and 
  angles 
  in 
  the 
  case 
  of 
  the 
  latter, 
  and 
  

   in 
  both 
  cases 
  to 
  produce 
  a 
  brick 
  of 
  more 
  regular 
  size 
  and 
  greater 
  

   density. 
  

  

  The 
  repressing 
  is 
  done 
  in 
  a 
  machine 
  known 
  as 
  the 
  repress, 
  

   operated 
  either 
  by 
  hand 
  or 
  steam 
  power, 
  (pi. 
  36.) 
  In 
  the 
  hand 
  

   power 
  machine 
  only 
  one 
  brick 
  is 
  repressed 
  at 
  a 
  time, 
  and 
  one 
  man 
  

   and 
  a 
  boy 
  can 
  generally 
  repress 
  about 
  2000 
  a 
  day. 
  In 
  a 
  

   steam 
  power 
  machine 
  two 
  bricks 
  are 
  repressed 
  at 
  a 
  time, 
  and 
  the 
  

   capacity 
  is 
  about 
  25,000 
  a 
  day 
  of 
  10 
  hours. 
  In 
  each 
  case 
  the 
  

   pressure 
  is 
  applied 
  vertically, 
  and 
  the 
  dies 
  and 
  other 
  parts 
  of 
  the 
  

   machine 
  have 
  to 
  be 
  oiled 
  frequently 
  to 
  keep 
  the 
  clay 
  from 
  sticking. 
  

  

  Eepressing 
  reduces 
  the 
  volume 
  of 
  the 
  brick 
  somewhat, 
  thus 
  in 
  

   one 
  case 
  a 
  brick 
  before 
  being 
  repressed 
  in 
  a 
  steam 
  power 
  machine 
  

   measured 
  8| 
  x 
  4f 
  x 
  3^ 
  inches, 
  and 
  after 
  it 
  8li- 
  x 
  4§ 
  x 
  2|-. 
  

  

  Drying 
  

  

  The 
  methods 
  employed 
  have 
  already 
  been 
  enumerated 
  in 
  the 
  

   table 
  given 
  on 
  page 
  655. 
  

  

  "With 
  few 
  exceptions 
  artificial 
  drying 
  is 
  used 
  only 
  in 
  connection 
  

   with 
  the 
  stiff 
  mud 
  and 
  dry 
  press 
  process. 
  The 
  drying 
  of 
  bricks 
  

   should 
  never 
  be 
  hurried, 
  as 
  bricks 
  dried 
  too 
  quickly 
  are 
  apt 
  to 
  

   crack; 
  but 
  some 
  clays 
  can 
  be 
  dried 
  much 
  more 
  rapidly 
  than 
  others, 
  

   and 
  so 
  the 
  drying 
  capacity 
  of 
  the 
  plant 
  does 
  not 
  need 
  to 
  be 
  as 
  great 
  

   as 
  in 
  the 
  case 
  of 
  clays 
  that 
  dry 
  slowly. 
  

  

  