﻿392 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  does 
  not 
  evolve 
  much 
  heat. 
  The 
  tensile 
  strength 
  can 
  be 
  greatly 
  

   increased 
  by 
  the 
  addition 
  of 
  sand, 
  even 
  more 
  so 
  than 
  in 
  the 
  case 
  

   of 
  hydraulic 
  lime. 
  

  

  3 
  Dolomitic 
  cements. 
  These 
  are 
  made 
  from 
  magnesiah 
  lime- 
  

   stone 
  and 
  are 
  to 
  be 
  looked 
  on 
  as 
  only 
  a 
  variety 
  of 
  roman 
  

   cement, 
  and 
  indeed 
  they 
  are 
  sometimes 
  sold 
  under 
  that 
  name. 
  

   The 
  dolomites 
  have 
  54 
  . 
  3 
  of 
  lime 
  carbonate 
  and 
  45 
  . 
  7 
  of 
  magnesia 
  

   carbonate. 
  Other 
  impurities 
  are 
  frequently 
  present. 
  Dolomites 
  

   are 
  found 
  in 
  many 
  parts 
  of 
  the 
  world, 
  Germany, 
  Scotland, 
  Russia, 
  

   Belgium 
  and 
  America. 
  Such 
  cements 
  must 
  be 
  heated 
  to 
  a 
  tem- 
  

   perature 
  only 
  sufficient 
  to 
  drive 
  the 
  CO 
  off 
  from 
  the 
  magnesia. 
  

   It 
  should 
  not 
  as 
  a 
  rule 
  exceed 
  400 
  C. 
  If 
  they 
  are 
  burned 
  too 
  hard 
  

   quicklime 
  is 
  formed, 
  which 
  will 
  not 
  develop 
  hydraulic 
  properties 
  

   except 
  in 
  those 
  materials 
  containing 
  clay 
  in 
  large 
  amounts. 
  The 
  

   quicklime 
  in 
  this 
  case 
  will 
  form 
  hydraulic 
  compounds 
  by 
  uniting 
  

   with 
  the 
  silicates 
  and 
  these 
  do 
  not 
  expand 
  noticeably 
  in 
  the 
  

   water. 
  Dolomitic 
  cements 
  do 
  not 
  develop 
  much 
  heat 
  on 
  mixing 
  

   with 
  water. 
  Their 
  tensile 
  strength 
  alone 
  as 
  well 
  as 
  when 
  mixed 
  

   with 
  sand 
  is 
  intermediate 
  between 
  true 
  hydraulic 
  lime 
  and 
  roman 
  

   cement. 
  

  

  The 
  Rosendale 
  region 
  of 
  New 
  York 
  is 
  one 
  of 
  the 
  best 
  producers 
  

   of 
  natural 
  cement 
  in 
  this 
  country. 
  Hydraulic 
  limestone 
  is 
  found 
  

   more 
  or 
  less 
  in 
  many 
  states 
  specially 
  those 
  of 
  the 
  Appalachian 
  

   region 
  of 
  the 
  east. 
  Others 
  occur 
  in 
  the 
  west 
  and 
  in 
  the 
  region 
  of 
  

   the 
  great 
  lakes. 
  Some 
  idea 
  may 
  be 
  gained 
  of 
  the 
  extent 
  of 
  this 
  

   industry 
  at 
  the 
  present 
  day 
  by 
  stating 
  that 
  the 
  works 
  for 
  making 
  

   natural 
  hydraulic 
  cements 
  are 
  fouDd 
  in 
  New 
  York, 
  Pennsylvania, 
  

   Maryland, 
  Virginia, 
  West 
  Virginia, 
  Ohio, 
  Illinois, 
  Kentucky, 
  Min- 
  

   nesota, 
  Kansas, 
  Utah, 
  New 
  Mexico, 
  Wisconsin 
  and 
  Texas. 
  Ac- 
  

   cording 
  to 
  the 
  U. 
  S. 
  geological 
  survey 
  there 
  were 
  71 
  plants 
  in 
  

   operation 
  in 
  1896, 
  which 
  produced 
  7,970,450 
  barrels 
  of 
  natural 
  

   cement 
  worth 
  $4,049,202. 
  Over 
  50$ 
  of 
  this 
  was 
  made 
  in 
  New 
  

   York. 
  In 
  fact 
  it 
  was 
  in 
  New 
  York 
  state 
  that 
  the 
  first 
  natural 
  

   cement 
  in 
  this 
  country 
  was 
  made, 
  and 
  the 
  United 
  States 
  exceeds 
  

   all 
  other 
  countries 
  of 
  the 
  world 
  in 
  the 
  quantity 
  of 
  natural 
  cement 
  

   produced. 
  As 
  mentioned 
  in 
  another 
  portion 
  of 
  this 
  report 
  how- 
  

   ever 
  portland 
  cements 
  are 
  rapidly 
  crowding 
  out 
  the 
  natural 
  hy- 
  

  

  