﻿THE 
  MIXING 
  AND 
  QUARRY 
  INDUSTRY 
  I908 
  57 
  

  

  Sharp, 
  angular 
  sand 
  free 
  from 
  clay, 
  sandy 
  loam, 
  clayey 
  sand 
  and 
  

   even 
  fine 
  gravel 
  are 
  all 
  used 
  in 
  the 
  foundries, 
  but 
  the 
  material 
  

   having 
  by 
  far 
  the 
  most 
  universal 
  use 
  and 
  serving 
  the 
  most 
  purposes, 
  

   is 
  a 
  fine 
  grained 
  clayey 
  sand 
  or 
  loam, 
  and 
  it 
  will 
  be 
  the 
  only 
  type 
  of 
  

   molding 
  sand 
  discussed 
  in 
  this 
  paper. 
  

  

  Although 
  an 
  experienced 
  foundryinan 
  can 
  usually 
  gage 
  quite 
  

   accurately 
  the 
  value 
  of 
  a 
  sand 
  by 
  an 
  ordinary 
  visual 
  examination 
  

   and 
  the 
  '' 
  feel 
  " 
  of 
  a 
  moist 
  sample, 
  yet 
  there 
  are 
  definite 
  qualities 
  

   which 
  a 
  sand 
  must 
  possess 
  in 
  order 
  to 
  be 
  classed 
  as 
  a 
  brass 
  sand, 
  

   core 
  sand, 
  sand 
  for 
  rough 
  castings, 
  etc. 
  

  

  A 
  pure 
  white 
  quartz 
  sand 
  when 
  moistened 
  and 
  packed 
  into 
  a 
  

   definite 
  form, 
  seems 
  to 
  have 
  no 
  tendency 
  to 
  " 
  stand 
  up 
  " 
  well 
  in 
  a 
  

   firm 
  mass, 
  but 
  on 
  the 
  slightest 
  touch 
  crumbles 
  and 
  falls 
  apart. 
  In 
  

   casting, 
  the 
  sand 
  must 
  be 
  of 
  such 
  a 
  character 
  that 
  after 
  firmly 
  

   tamping 
  it 
  around 
  the 
  pattern, 
  the 
  latter 
  may 
  be 
  drawn 
  out 
  and 
  the 
  

   walls 
  or 
  projections 
  of 
  the 
  cavity 
  will 
  retain 
  their 
  position 
  until 
  

   the 
  metal 
  can 
  be 
  poured 
  in, 
  and 
  also 
  exposed 
  portions 
  must 
  resist 
  

   the 
  abrading 
  action 
  of 
  the 
  stream 
  of 
  metal. 
  This 
  property 
  is 
  termed 
  

   the 
  " 
  bonding 
  power 
  " 
  and 
  can 
  be 
  measured 
  by 
  various 
  means 
  such 
  

   as 
  by 
  making 
  briquets 
  of 
  the 
  sand 
  and 
  determining 
  their 
  tensile 
  

   strength. 
  The 
  chief 
  factors 
  determining 
  the 
  bonding 
  power 
  are 
  (i) 
  

   the 
  amount 
  of 
  clay 
  present 
  in 
  the 
  sand; 
  (2) 
  the 
  amount 
  of 
  water 
  

   with 
  which 
  it 
  was 
  tempered; 
  (3) 
  the 
  amount 
  of 
  tamping 
  given 
  it. 
  

   In 
  special 
  cases 
  various 
  clays 
  or 
  certain 
  organic 
  substances 
  are 
  

   added 
  to 
  increase 
  the 
  bonding 
  power. 
  In 
  a 
  series 
  of 
  tests 
  made 
  on 
  

   molding 
  sands 
  of 
  Wisconsin^ 
  the 
  clay 
  percentage 
  ranged 
  from 
  a 
  

   slight 
  amount 
  up 
  to 
  39.44 
  per 
  cent 
  with 
  an 
  average 
  in 
  34 
  samples 
  

   of 
  13.18 
  per 
  cent. 
  After 
  the 
  sand 
  has 
  been 
  several 
  times 
  subjected 
  

   to 
  the 
  heat 
  in 
  casting, 
  its 
  clay 
  content 
  becomes 
  dehydrated, 
  loses 
  its 
  

   plasticity 
  and 
  bonding 
  power 
  and 
  the 
  sand 
  becomes 
  " 
  dead." 
  

  

  Permeability 
  is 
  the 
  property 
  .which 
  .'all 
  molding 
  sands 
  must 
  

   possess 
  to 
  a 
  certain 
  extent, 
  of 
  allowing 
  the 
  steam, 
  heated 
  air, 
  or 
  

   other 
  gases 
  to 
  pass 
  through 
  the 
  pores 
  of 
  the 
  sand 
  and 
  escape 
  during 
  

   the 
  casting. 
  The 
  permeability 
  of 
  a 
  sand 
  depends 
  upon 
  the 
  amount 
  

   of 
  pore 
  space 
  or 
  voids 
  and 
  upon 
  the 
  shape 
  and 
  size 
  of 
  such 
  voids, 
  

   the 
  latter 
  factor 
  being 
  as 
  important 
  as 
  the 
  former. 
  The 
  work 
  of 
  

   King 
  and 
  Slichter^ 
  has 
  demonstrated 
  that- 
  the 
  porosity 
  of 
  a 
  sand 
  

   depends 
  on 
  the 
  size 
  and 
  arrangement 
  of 
  the 
  grains, 
  that 
  a 
  sand 
  

   composed 
  of 
  well 
  rounded 
  grains 
  will 
  have 
  a 
  smaller 
  amount 
  of 
  

  

  i 
  Ries. 
  Wis. 
  Geol. 
  Siir. 
  Bui. 
  15. 
  1906. 
  p. 
  205. 
  

  

  2U. 
  S. 
  Geol. 
  Siir. 
  i^tli 
  An. 
  Rep't, 
  pt. 
  2, 
  p. 
  209-15, 
  306. 
  

  

  