﻿Report 
  of 
  the 
  State 
  Geologist. 
  469 
  

  

  The 
  peculiar 
  qualities 
  which 
  go 
  to 
  make 
  up 
  a 
  molding 
  sand 
  

   consist 
  of 
  elasticity, 
  strength, 
  and 
  of 
  a 
  certain 
  degree 
  of 
  fineness. 
  

   It 
  must 
  be 
  plastic 
  in 
  order 
  to 
  be 
  molded 
  around 
  the 
  pattern 
  ; 
  it 
  

   must 
  have 
  sufficient 
  strength 
  to 
  stand 
  when 
  unsupported 
  by 
  the 
  

   pattern, 
  and 
  to 
  resist 
  the 
  impact 
  of 
  the 
  molten 
  metal 
  when 
  

   poured 
  into 
  the 
  moid. 
  Too 
  much 
  clay 
  and 
  iron 
  present 
  in 
  the 
  

   sand 
  will 
  cause 
  the 
  mold 
  to 
  shrink 
  and 
  crack 
  under 
  the 
  intense 
  

   heat, 
  too 
  little 
  will 
  cause 
  it 
  to 
  dry 
  and 
  crumble, 
  if 
  not 
  to 
  entirely 
  

   collapse. 
  The 
  purpose 
  for 
  which 
  the 
  sand 
  is 
  used 
  depends 
  

   upon 
  its 
  fineness. 
  For 
  very 
  heavy 
  castings 
  very 
  heavy 
  coarse 
  

   sand 
  must 
  be 
  employed 
  ; 
  but 
  for 
  the 
  finer 
  grades 
  and 
  lighter 
  

   castings, 
  such 
  as 
  brass, 
  stove 
  plates, 
  and 
  light 
  steel, 
  where 
  smooth 
  

   surfaces 
  and 
  sharp 
  edges 
  and 
  lines 
  are 
  to 
  be 
  produced, 
  only 
  the 
  

   finest 
  grades 
  can 
  be 
  employed. 
  In 
  many 
  places 
  where 
  this 
  pecu- 
  

   liar 
  sand 
  is 
  not 
  found 
  and 
  where 
  freights 
  are 
  too 
  expensive, 
  an 
  

   inferior 
  grade 
  is 
  made 
  by 
  mixing 
  quicksand 
  with 
  clay, 
  flour 
  and 
  

   treacle. 
  Though 
  r 
  o 
  chemical 
  analyses 
  of 
  the 
  molding 
  sands 
  were 
  

   made, 
  the 
  physical 
  differences 
  between 
  quicksands 
  and 
  molding 
  

   sands 
  are 
  easily 
  discerned. 
  Quicksands 
  are 
  composed 
  principally 
  of 
  

   grains 
  of 
  quartz, 
  with 
  magnetite, 
  garnet, 
  feldspar, 
  slate, 
  etc. 
  Such 
  

   sands 
  when 
  dry 
  have 
  no 
  stability 
  or 
  plasticity, 
  but 
  when 
  mixed 
  

   with 
  water 
  have 
  a 
  distinct 
  flow, 
  hence 
  the 
  name 
  quicksand. 
  If, 
  

   either 
  naturally 
  or 
  artificially, 
  these 
  same 
  sands, 
  when 
  of 
  uniform 
  

   size, 
  be 
  mixed 
  thoroughly 
  with 
  a 
  certain 
  amount 
  of 
  fine 
  clay 
  

   they 
  become 
  plastic, 
  will 
  stand 
  perpendicularly 
  when 
  moist 
  or 
  

   even 
  dry, 
  or 
  will 
  overhang. 
  The 
  sands 
  then 
  are 
  known 
  as 
  mold- 
  

   ing 
  sand. 
  It 
  might 
  at 
  first 
  thought 
  seem 
  a 
  very 
  easy 
  matter 
  

   to 
  make 
  an 
  artificial 
  molding 
  sand 
  of 
  equal 
  value 
  to 
  the 
  natural. 
  

   In 
  fact, 
  however, 
  this 
  is 
  quite 
  difficult, 
  if 
  not 
  impos^ble. 
  If 
  the 
  

   grains 
  of 
  sand 
  in 
  the 
  natural 
  material 
  be 
  closely 
  examined 
  with 
  

   a 
  pocket 
  lens 
  it 
  will 
  be 
  seen 
  that 
  each 
  is 
  coated 
  with 
  a 
  film 
  of 
  

   clay. 
  It 
  thus 
  follows 
  that 
  if 
  any 
  two 
  grains 
  be 
  brought 
  into 
  

   contact 
  when 
  moistened 
  they 
  will 
  adhere. 
  If 
  now 
  these 
  grains 
  

   be 
  heated 
  to 
  redness 
  their 
  plasticity 
  or 
  capacity 
  for 
  adherence 
  

   has 
  been 
  destroyed, 
  and 
  they 
  become 
  practically 
  quicksands. 
  

   That 
  is, 
  the 
  clay 
  and 
  iron 
  have 
  been 
  dehydrated, 
  or 
  all 
  the 
  water 
  

   chemically 
  combined 
  has 
  been 
  driven 
  off. 
  Every 
  molder 
  or 
  

   foundryman 
  knows 
  that 
  when 
  the 
  best 
  sand 
  has 
  been 
  used 
  for 
  

   casting 
  alter 
  awhile 
  it 
  becomes 
  lifeless, 
  and 
  it 
  is 
  then 
  said 
  to 
  be 
  

   " 
  burned." 
  

  

  