﻿388 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  The 
  theoretic 
  increase 
  is 
  1.53. 
  Lime 
  also 
  slakes 
  simply 
  on 
  ex- 
  

   posure 
  to 
  the 
  air 
  but 
  it 
  is 
  not 
  good 
  for 
  mortar 
  making 
  as 
  it& 
  

   slaking 
  has 
  been 
  accompanied 
  without 
  any 
  violent 
  disengage- 
  

   ment 
  of 
  heat 
  to 
  rupture 
  the 
  mass. 
  

  

  The 
  larger 
  particles 
  also 
  have 
  a 
  hardened 
  rim. 
  

  

  Method 
  of 
  slaking. 
  The 
  water 
  may 
  be 
  sprinkled 
  over 
  the 
  lime 
  

   gradually, 
  or 
  added 
  at 
  once 
  in 
  excess. 
  

  

  The 
  former 
  is 
  best 
  because 
  a 
  looser 
  mass 
  is 
  obtained, 
  and 
  it 
  

   gives 
  better 
  results 
  with 
  poorer 
  limes, 
  slaking 
  them 
  more 
  

   thoroughly. 
  

  

  Too 
  great 
  an 
  excess 
  of 
  water 
  tends 
  to 
  lower 
  the 
  temperature 
  

   and 
  render 
  the 
  slaking 
  incomplete. 
  This 
  latter 
  causes 
  unslaked 
  

   particles 
  to 
  get 
  into 
  mortar, 
  and 
  by 
  their 
  subsequent 
  slow 
  hy- 
  

   dration 
  and 
  expansion 
  they 
  may 
  do 
  much 
  harm. 
  Popping 
  of 
  

   mortar 
  is 
  due 
  to 
  this 
  cause. 
  It 
  is 
  also 
  true 
  that 
  if 
  the 
  water 
  is 
  

   added 
  gradually 
  it 
  may 
  allow 
  the 
  mass 
  to 
  cool 
  down. 
  Enough 
  

   water 
  should 
  be 
  added 
  to 
  allow 
  for 
  that 
  escaping 
  as 
  steam. 
  

   With 
  very 
  fat 
  lime 
  2£ 
  volumes 
  of 
  water 
  may 
  be 
  taken. 
  Poor 
  

   magnesian 
  limes 
  take 
  less. 
  

  

  Pure 
  water 
  should 
  be 
  used. 
  That 
  with 
  soluble 
  salts 
  gives 
  rise 
  

   to 
  efflorescence. 
  Hence 
  sea 
  water 
  can 
  not 
  be 
  used 
  though 
  it 
  has 
  

   been 
  successfully 
  tried 
  for 
  hydraulic 
  cement. 
  

  

  An 
  excess 
  of 
  water 
  gives 
  granular 
  paste 
  and 
  also 
  makes 
  the 
  

   mortar 
  porous. 
  

  

  In 
  making 
  mortar 
  the 
  sand 
  is 
  added 
  to 
  lime 
  for 
  economy 
  and 
  

   to 
  prevent 
  shrinkage. 
  Sand 
  should 
  be 
  clean 
  and 
  sharp 
  and 
  should 
  

   be 
  in 
  such 
  quantity 
  that 
  the 
  lime 
  will 
  fill 
  all 
  the 
  interstices. 
  If 
  

   an 
  excess 
  of 
  sand 
  is 
  used 
  the 
  bond 
  is 
  poor. 
  If 
  too 
  little 
  sand 
  is 
  

   used 
  the 
  mortar 
  shrinks 
  and 
  cracks. 
  If 
  too 
  little 
  lime 
  is 
  used 
  

   the 
  paste 
  is 
  made 
  thin. 
  In 
  ordinary 
  sands 
  the 
  spaces 
  from 
  30 
  to 
  

   40$ 
  of 
  the 
  total 
  volume 
  and 
  in 
  such 
  1 
  vol. 
  paste 
  fills 
  voids 
  of 
  

   2J 
  vols, 
  sand 
  (Brickbuilder 
  p. 
  101, 
  1897). 
  In 
  practice 
  1.25 
  to 
  2 
  

   vols, 
  of 
  sand 
  to 
  one 
  of 
  paste 
  is 
  used. 
  This 
  in 
  case 
  of 
  fat 
  lime 
  

   means 
  3 
  to 
  5 
  vols, 
  of 
  sand 
  to 
  one 
  measured 
  vol. 
  of 
  lime 
  and 
  

   this 
  gives 
  a 
  plastic 
  mortar 
  which 
  does 
  not 
  crack. 
  

  

  