﻿LIMESTONES 
  OF 
  NEW 
  YORK 
  AND 
  THEIR 
  ECONOMIC 
  VALUE 
  395- 
  

  

  determined 
  by 
  dissolving 
  a 
  weighed 
  fragment 
  in 
  acid 
  and 
  deter- 
  

   mining 
  the 
  size 
  and 
  quantity 
  of 
  the 
  insoluble 
  particles 
  of 
  sand 
  

   remaining. 
  The 
  residue 
  of 
  the 
  Rosendale 
  found 
  at 
  various 
  

   depths 
  are 
  quoted 
  by 
  Richardson 
  as 
  follows: 
  

  

  Per 
  cent 
  of 
  residue 
  

   "NToorP«f 
  smrfnpp 
  on 
  sieve 
  200 
  mesh, 
  

  

  -TNecUfcJfe'l 
  feUlld.Lt; 
  100 
  mesh, 
  50 
  mesh, 
  

  

  Light 
  rock 
  . 
  2.9 
  

  

  Dark 
  rock 
  ' 
  0.0 
  

  

  Medium 
  

  

  Light 
  rock 
  0.0 
  

  

  Dark 
  rock 
  0.0 
  

  

  Deepest 
  

  

  ' 
  Light 
  rock 
  . 
  .. 
  0.6 
  0.6 
  0.4 
  

  

  Dark 
  rock 
  1.2 
  0.5 
  0.3 
  

  

  On 
  treatment 
  with 
  acids 
  the 
  rock 
  retains 
  its 
  shape 
  but 
  the 
  clay 
  

   is 
  dissolved 
  out 
  and 
  the 
  residue 
  can 
  then 
  be 
  broken 
  down 
  with 
  

   the 
  fingers. 
  If 
  a 
  coarse 
  rock 
  must 
  be 
  used 
  the 
  burning 
  should 
  be- 
  

   slow 
  in 
  order 
  to 
  give 
  a 
  combination 
  between 
  the 
  lime 
  and 
  silica 
  

   every 
  possible 
  chance 
  to 
  take 
  place. 
  

  

  Chemical 
  composition 
  of 
  natural 
  cements. 
  The 
  amount 
  of 
  car- 
  

   bonate 
  in 
  each 
  hydraulic 
  limestone 
  must 
  not 
  exceed 
  75$ 
  and 
  prefer- 
  

   ably 
  70$, 
  and 
  where 
  the 
  quarry 
  contains 
  several 
  strata 
  of 
  different 
  

   degrees 
  of 
  richness 
  it 
  is 
  possible 
  to 
  bring 
  about 
  the 
  proper 
  composi- 
  

   tion 
  by 
  mixing 
  the 
  magnesian 
  stone, 
  probably 
  making 
  the 
  beet 
  ce- 
  

   ment 
  known 
  provided 
  they 
  contain 
  enough 
  clay. 
  Yet 
  the 
  Maryland 
  

   rock 
  with 
  .68 
  and 
  .44$ 
  of 
  carbonate 
  and 
  only 
  4.58 
  of 
  magnesia, 
  

   while 
  the 
  silica 
  and 
  clay 
  amount 
  to 
  29.66$, 
  are 
  examples 
  of 
  this 
  

   kind. 
  In 
  any 
  single 
  rock 
  the 
  amount 
  of 
  magnesia 
  should 
  not 
  

   exceed 
  40$ 
  and 
  should 
  preferably 
  be 
  25$. 
  A 
  stone 
  with 
  more 
  

   than 
  this 
  latter 
  amount 
  has 
  a 
  tendency 
  to 
  expand 
  slowly 
  with 
  

   age 
  specially 
  if 
  it 
  runs 
  low 
  in 
  clay. 
  A 
  western 
  New 
  York 
  

   rock 
  with 
  37$ 
  of 
  carbonate 
  of 
  magnesia 
  and 
  less 
  than 
  2$ 
  of 
  silica 
  

   and 
  silicates 
  is 
  an 
  example 
  of 
  this. 
  The 
  Rosendale 
  cements 
  

   contain 
  only 
  about 
  20$ 
  of 
  magnesian 
  carbonate 
  with 
  30$ 
  

   of 
  clay. 
  The 
  amount 
  of 
  silica 
  and 
  silicates 
  present 
  is 
  highly 
  

   important 
  for 
  they 
  influence 
  the 
  hydraulic 
  properties 
  of 
  the 
  

  

  