﻿372 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  While 
  a 
  total 
  of 
  4$ 
  or 
  5^ 
  of 
  impurities 
  does 
  not 
  mean 
  much 
  

   when 
  only 
  a 
  few 
  tons 
  a 
  day 
  are 
  used, 
  it 
  becomes 
  an 
  appreciable 
  

   item 
  when 
  the 
  consumption 
  of 
  a 
  given 
  stone 
  by 
  one 
  works 
  is 
  200 
  

   or 
  350 
  tons 
  a 
  day. 
  

  

  Limestones 
  may 
  be 
  divided 
  into 
  lime 
  rock 
  and 
  cement 
  rock. 
  

   The 
  former 
  when 
  burned 
  falls 
  to 
  pieces 
  in 
  water 
  with 
  the 
  evolu- 
  

   tion 
  of 
  heat 
  or 
  slakes. 
  The 
  latter 
  when 
  burned 
  does 
  not 
  slake 
  but 
  

   forms 
  a 
  hard 
  mass 
  on 
  the 
  addition 
  of 
  water. 
  

  

  Uses 
  of 
  limestone 
  

   Furnace 
  flux 
  

  

  This 
  is 
  one 
  of 
  the 
  commonest 
  uses 
  of 
  limestone. 
  It 
  is 
  used 
  as 
  

   a 
  flux 
  for 
  both 
  lead 
  and 
  iron 
  ores. 
  In 
  the 
  blast-furnace 
  the 
  

   action 
  of 
  the 
  limestone 
  is 
  to 
  reduce 
  the 
  iron 
  to 
  its 
  metallic 
  state 
  

   and 
  also 
  flux 
  the 
  impurities 
  which 
  pass 
  off 
  as 
  slag. 
  

  

  The 
  purer 
  the 
  limestone 
  the 
  more 
  efficient 
  will 
  be 
  its 
  action 
  

   and 
  the 
  cheaper 
  its 
  use, 
  for 
  it 
  will 
  be 
  easily 
  seen 
  that 
  the 
  greater 
  

   the 
  percentage 
  of 
  impurities 
  the 
  more 
  limestone 
  will 
  be 
  required 
  

   to 
  do 
  the 
  same 
  amount 
  of 
  work. 
  

  

  For 
  reasons 
  of 
  economy 
  blast 
  furnace 
  operators 
  often 
  use 
  less 
  

   pure 
  but 
  more 
  easily 
  and 
  cheaply 
  obtained 
  limestones. 
  

  

  Some 
  time 
  ago 
  a 
  table 
  was 
  prepared 
  by 
  Mr 
  J. 
  M. 
  Hartmann 
  a 
  

   giving 
  the 
  value 
  of 
  limestone 
  containing 
  varying 
  amounts 
  of 
  

   silica, 
  lime 
  and 
  magnesia. 
  The 
  basis 
  of 
  the 
  calculation 
  is 
  mag- 
  

   nesian 
  limestone 
  at 
  56c 
  a 
  ton 
  and 
  fuel 
  at 
  $3.50 
  a 
  ton, 
  both 
  at 
  the 
  

   furnace. 
  

  

  a 
  Mineral 
  resources 
  of 
  U. 
  S. 
  1883-84, 
  p. 
  670. 
  

  

  