﻿380 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Lime 
  in 
  its 
  normal 
  condition 
  and 
  when 
  dry 
  is 
  totally 
  unaffected 
  

   by 
  carbonic 
  acid 
  gas 
  but 
  when 
  heated 
  takes 
  it 
  up 
  rather 
  quickly. 
  

   The 
  addition 
  of 
  water 
  to 
  lime 
  can 
  be 
  done 
  in 
  a 
  variety 
  of 
  ways. 
  

   according 
  to 
  the 
  degree 
  of 
  slaking 
  that 
  is 
  to 
  be 
  brought 
  about. 
  

  

  If 
  a 
  lump 
  of 
  quicklime 
  is 
  immersed 
  in 
  water 
  for 
  an 
  instant 
  it 
  

   saturates 
  itself 
  at 
  once 
  with 
  the 
  former, 
  and 
  this 
  absorption 
  is 
  

   accompanied 
  by 
  the 
  evolution 
  of 
  heat, 
  a 
  swelling 
  and 
  bursting 
  

   of 
  the 
  lime, 
  and 
  the 
  latter 
  finally 
  falls 
  to 
  a 
  fine 
  powder, 
  the 
  

   hydrate 
  of 
  lime 
  Ca(OH) 
  2 
  . 
  The 
  chemical 
  action 
  which 
  has 
  taken 
  

   place 
  is 
  expressed 
  by 
  the 
  following 
  formula. 
  

  

  CaO 
  + 
  H 
  2 
  =: 
  Ca(OH) 
  2 
  

  

  This 
  method 
  of 
  hydration 
  is 
  considered 
  to 
  be 
  better 
  than 
  pour- 
  

   ing 
  the 
  water 
  on 
  the 
  lime. 
  

  

  The 
  hydrate 
  of 
  lime 
  thus 
  obtained 
  is 
  a 
  fine 
  white 
  powder 
  of 
  a 
  

   specific 
  gravity 
  of 
  2.1. 
  Its 
  water 
  of 
  hydration 
  is 
  pretty 
  firmly 
  

   combined 
  and 
  is 
  only 
  driven 
  off 
  by 
  reheating 
  to 
  redness. 
  

  

  On 
  the 
  other 
  hand 
  quicklime 
  can 
  be 
  made 
  by 
  adding 
  the 
  lumps 
  

   of 
  lime 
  piece 
  by 
  piece 
  to 
  the 
  water 
  till 
  a 
  strong 
  paste 
  is 
  formed 
  

   by 
  stirring 
  the 
  mass. 
  The 
  stirring 
  is 
  specially 
  necessary 
  in 
  the 
  

   case 
  of 
  lean 
  limes. 
  

  

  In 
  order 
  to 
  assist 
  the 
  slaking 
  of 
  such 
  lean 
  limes 
  it 
  has 
  been 
  

   found 
  advisable 
  to 
  use 
  only 
  one 
  third 
  the 
  necessary 
  amount 
  of 
  

   water 
  at 
  first 
  and 
  add 
  the 
  other 
  two 
  thirds 
  later 
  on. 
  Again, 
  as 
  

   the 
  lean 
  lime 
  gives 
  out 
  much 
  less. 
  heat 
  it 
  is 
  well 
  to 
  keep 
  the 
  mix- 
  

   ing 
  pan 
  covered 
  in 
  order 
  to 
  prevent 
  its 
  escaping. 
  Lean 
  lime 
  also 
  

   slakes 
  better 
  if 
  a 
  certain 
  amount 
  of 
  fat 
  lime 
  is 
  worked 
  in 
  with 
  

   it. 
  The 
  latter 
  has 
  a 
  sort 
  of 
  contact 
  effect 
  on 
  the 
  former, 
  which 
  

   is 
  effective 
  and 
  rapid. 
  This 
  method 
  is 
  a 
  good 
  one 
  to 
  follow 
  in 
  

   using 
  overburned 
  lime. 
  

  

  An 
  excess 
  of 
  water 
  in 
  slaking 
  is 
  undesirable, 
  as 
  it 
  only 
  tends 
  to 
  

   lower 
  the 
  temperature 
  of 
  the 
  mixture. 
  It 
  is 
  sometimes 
  desirable 
  

   to 
  use 
  hot 
  water. 
  

  

  The 
  hydration 
  of 
  lime 
  powder 
  or 
  slaking 
  to 
  a 
  pasty 
  mass 
  must 
  

   be 
  carried 
  out 
  very 
  carefully, 
  as 
  otherwise, 
  specially 
  in 
  the 
  case 
  , 
  

   of 
  overburned 
  lime, 
  some 
  unslaked 
  particles 
  will 
  remain, 
  which 
  

   may 
  slake 
  later 
  and 
  make 
  themselves 
  unpleasantly 
  prominent. 
  

  

  