﻿LIMESTONES 
  OF 
  NEW 
  YORK 
  AND 
  THEIR 
  ECONOMIC 
  VALUE 
  413 
  

  

  logically. 
  As 
  the 
  cement 
  is 
  made 
  from 
  artificial 
  mixtures 
  it 
  i& 
  

   frequently 
  possible 
  to 
  use 
  all 
  grades 
  of 
  limestone 
  and 
  clay 
  bear- 
  

   ing 
  rocks. 
  Though 
  portland 
  cement 
  is 
  made 
  at 
  many 
  places 
  

   and 
  from 
  material 
  of 
  widely 
  different 
  character, 
  portland 
  cement 
  

   materials 
  are 
  not 
  so 
  very 
  numerous 
  and 
  the 
  raw 
  products 
  have 
  

   to 
  be 
  mixed 
  within 
  narrow 
  limits. 
  The 
  following 
  analyses 
  are 
  

   given 
  by 
  Lewis 
  in 
  volume 
  7 
  of 
  the 
  Mineral 
  industry, 
  the 
  European 
  

   being 
  given 
  for 
  the 
  purposes 
  of 
  comparison. 
  Following 
  them 
  is 
  

   also 
  given 
  a 
  table 
  showing 
  the 
  composition 
  of 
  both 
  the 
  American 
  

   and 
  European 
  brands 
  of 
  cements. 
  

  

  