﻿408 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  quality. 
  Compounds 
  with 
  too 
  much 
  clay 
  fuse 
  too 
  easily 
  and 
  the 
  

   resulting 
  cement 
  is 
  light 
  in 
  weight, 
  sets 
  quickly, 
  has 
  a 
  brownish 
  

   color 
  and 
  never 
  becomes 
  thoroughly 
  hard 
  (ibid 
  p. 
  39). 
  Moreover 
  

   it 
  crumjbles 
  when 
  exposed 
  to 
  the 
  weather. 
  Overlimed 
  cements, 
  

   that 
  is 
  where 
  the 
  part 
  made 
  of 
  lime 
  in 
  the 
  slurry 
  ranges 
  above 
  77$ 
  

   or 
  78$, 
  give 
  a 
  cement 
  which 
  will 
  stand 
  the 
  hottest 
  fire 
  without 
  

   fusing. 
  

  

  Such 
  cements 
  when 
  burned 
  are 
  slow 
  setting 
  and 
  hard 
  to 
  grind, 
  

   and 
  portland 
  cement 
  made 
  from 
  such 
  mixtures 
  is 
  liable 
  to 
  flow 
  

   and 
  swell. 
  

  

  In 
  Europe 
  the 
  clay 
  is 
  generally 
  mixed 
  with 
  marl 
  or 
  chalk, 
  but 
  

   in 
  this 
  country 
  comparatively 
  little 
  marl 
  is 
  used. 
  In 
  this 
  country 
  

   Prof. 
  S. 
  Newberry 
  a 
  gives 
  20 
  works 
  as 
  mixing 
  limestone 
  with 
  

   the 
  clay, 
  and 
  seven 
  using 
  marl, 
  and 
  of 
  these 
  latter 
  four 
  are 
  in 
  

   New 
  York 
  state. 
  

  

  Marl 
  is 
  cheaper 
  to 
  use 
  for 
  the 
  manufacture 
  of 
  portland 
  cement 
  

   as 
  it 
  is 
  softer 
  and 
  finer 
  grained 
  and 
  consequently 
  needs 
  little 
  

   grinding. 
  It 
  always 
  has 
  a 
  large 
  percentage 
  of 
  moisture 
  which 
  

   must 
  be 
  expelled. 
  

  

  Redgrave 
  gives 
  the 
  following 
  analyses 
  of 
  English 
  portland 
  

   cement 
  mixtures: 
  l 
  

  

  1 
  Mixture 
  made 
  at 
  Folkestone 
  from 
  gray 
  chalk 
  and 
  gault 
  clay. 
  

  

  2 
  Forest 
  of 
  Dean 
  limestone 
  and 
  clay. 
  

  

  3 
  Mixture 
  from 
  Barrow 
  lias 
  quarries. 
  

  

  All 
  dried 
  at 
  100° 
  C. 
  but 
  2 
  and 
  3 
  have 
  perhaps 
  also 
  lost 
  

   some 
  H 
  2 
  0. 
  

  

  12 
  3 
  

  

  Sand 
  2.50 
  5.57 
  2.58 
  

  

  Silica 
  11.83 
  9.61 
  11.41 
  

  

  Ferric 
  oxid 
  1.97 
  2.42 
  2.34 
  

  

  Alumina 
  5.23 
  3.45 
  4.80 
  

  

  Iron 
  pyrites 
  tr 
  .43 
  

  

  Calcium 
  carbonate 
  74.18 
  75.89 
  74.09 
  

  

  Magnesium 
  carbonate 
  1.29 
  1.50 
  2.61 
  

  

  Calcium 
  sulfate 
  18 
  .16 
  .21 
  

  

  Potash 
  90 
  .88 
  .93 
  

  

  Soda 
  31 
  .39 
  .46 
  

  

  Water 
  1.82 
  .61 
  .43 
  

  

  aMineral 
  resources 
  of 
  U. 
  S. 
  20th 
  rep't 
  U. 
  S. 
  geol. 
  surv. 
  pt 
  6. 
  

  

  