﻿58 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  pore 
  space 
  when 
  tamped 
  than 
  a 
  sharp, 
  angular 
  sand, 
  that 
  a 
  fine 
  

   grained 
  sand 
  will 
  usually 
  have 
  a 
  greater 
  porosity 
  than 
  a 
  coarse 
  

   grained, 
  and 
  that 
  the 
  minimum 
  porosity 
  can 
  be 
  obtained 
  by 
  a 
  

   mixture 
  of 
  rounded 
  grains 
  of 
  several 
  sizes. 
  

  

  If 
  a 
  sand 
  does 
  not 
  possess 
  the 
  desired 
  permeability 
  a 
  mixture 
  of 
  

   some 
  other 
  sand 
  is 
  often 
  added 
  to 
  increase 
  the 
  pore 
  space. 
  The 
  

   coarser 
  sands, 
  since 
  they 
  have 
  the 
  larger 
  pores, 
  although 
  their 
  total 
  

   porosity 
  may 
  be 
  less 
  than 
  a 
  fine 
  sand, 
  have 
  usually 
  the 
  greater 
  

   permeability. 
  

  

  The 
  size 
  of 
  the 
  particles 
  is 
  of 
  importance 
  in 
  determining 
  the 
  use 
  

   of 
  the 
  sand. 
  For 
  a 
  brass 
  casting, 
  for 
  small 
  iron 
  castings 
  or 
  for 
  any 
  

   work 
  which 
  requires 
  delicate 
  lines 
  in 
  the 
  mold, 
  a 
  fine 
  sand 
  is 
  very 
  

   essential, 
  and 
  sand 
  for 
  such 
  work 
  usually 
  will 
  pass 
  almost 
  com- 
  

   pletely 
  through 
  a 
  sieve 
  with 
  100 
  meshes 
  to 
  the 
  inch. 
  Sands 
  for 
  

   general 
  iron 
  casting 
  are 
  often 
  much 
  coarser, 
  while 
  the 
  sands 
  used 
  

   in 
  making 
  cores 
  are 
  very 
  coarse, 
  sometimes 
  almost 
  ranging 
  into 
  

   gravels. 
  

  

  Chemical 
  analysis, 
  although 
  of 
  less 
  importance 
  than 
  a 
  physical 
  

   examination, 
  sometimes 
  indicates 
  the 
  importance 
  of 
  detrimental 
  

   impurities 
  such 
  as 
  calcium 
  carbonate, 
  an 
  excess 
  of 
  iron 
  oxids,, 
  etc. 
  

   Microscopic 
  examination 
  may 
  also 
  show 
  certain 
  minerals 
  which 
  

   would 
  be 
  easily 
  attacked 
  by 
  the 
  hot 
  metal, 
  but 
  ordinarily 
  these 
  are 
  

   of 
  rare 
  occurrence 
  in 
  molding 
  sands. 
  

  

  Distribution. 
  As 
  we 
  have 
  already 
  seen, 
  sands 
  used 
  for 
  molding 
  

   purposes 
  have 
  a 
  wide 
  range 
  in 
  character 
  and 
  are 
  therefore 
  not 
  

   strictly 
  limited 
  to 
  one 
  type 
  of 
  occurrence. 
  They 
  occur 
  both 
  as 
  

   residual 
  deposits, 
  alluvial 
  and 
  beach 
  sand 
  of 
  both 
  Quaternary 
  and 
  

   present 
  age 
  and 
  as 
  glacial 
  deposits, 
  all 
  of 
  which 
  types 
  are 
  repre- 
  

   sented 
  in 
  this 
  State. 
  The 
  most 
  widely 
  known 
  molding 
  sand 
  in 
  the 
  

   State 
  and 
  a 
  sand 
  recognized 
  as 
  a 
  standard 
  by 
  foundrymen 
  is 
  the 
  

   Quaternary 
  sands 
  bordering 
  the 
  Hudson 
  river 
  and 
  extensively 
  

   worked 
  in 
  Saratoga, 
  Schenectady 
  and 
  Albany 
  counties. 
  Other 
  

   counties 
  in 
  the 
  same 
  belt 
  producing 
  molding 
  sand 
  at 
  the 
  present 
  

   time 
  are 
  Essex, 
  Rensselaer, 
  Greene, 
  Dutchess, 
  Orange 
  and 
  Wash- 
  

   ington. 
  The 
  sand 
  throughout 
  this 
  area 
  is 
  very 
  easily 
  obtained, 
  as 
  

   it 
  lies 
  in 
  beds 
  covered 
  only 
  by 
  a 
  thin 
  coating 
  of 
  soil 
  or 
  sod. 
  The 
  

   soil 
  and 
  sod 
  over 
  an 
  area 
  of 
  a 
  few 
  rods 
  is 
  carefully 
  stripped 
  off 
  

   until 
  the 
  sand 
  is 
  reached. 
  The 
  sand 
  is 
  taken 
  out 
  and 
  transported 
  to 
  

   the 
  railroad 
  or 
  river 
  and 
  either 
  piled 
  in 
  large 
  rectangular 
  heaps 
  or 
  

   placed 
  directly 
  in 
  cars, 
  or 
  loaded 
  into 
  barges. 
  The 
  beds 
  of 
  good 
  

   sand 
  vary 
  from 
  8 
  inches 
  up 
  to 
  8 
  feet 
  in 
  thickness, 
  and 
  a 
  bed 
  i 
  foot 
  

  

  