﻿CLAYS 
  OF 
  NEW 
  YORK 
  541 
  

  

  muneric 
  expression 
  of 
  it 
  by 
  testing 
  the 
  tensile 
  strengtli 
  of 
  the 
  air- 
  

   dried 
  clay. 
  

  

  The 
  same 
  opinion 
  was 
  held 
  by 
  two 
  Russian 
  investigators, 
  W. 
  

   Aleksiejew 
  and 
  P. 
  A. 
  Cremiatschenski/ 
  who 
  hold 
  that 
  plasticity 
  

   is 
  not 
  only 
  due 
  to 
  the 
  interlocking 
  of 
  the 
  clay 
  particles, 
  but 
  varies 
  

   also 
  with 
  the 
  fineness 
  of 
  the 
  grains, 
  the 
  extreme 
  coarse 
  and 
  extreme 
  

   fine 
  ones 
  having 
  inferior 
  plasticity. 
  

  

  In 
  this 
  -country 
  Wheeler's 
  work 
  on 
  the 
  Missouri 
  clays 
  has 
  sub- 
  

   stantiated 
  these 
  views.^ 
  Experiments 
  by 
  the 
  writer 
  on 
  the 
  clays 
  of 
  

   North 
  Carolina, 
  Alabama, 
  New 
  York 
  and 
  other 
  states 
  incline 
  him 
  

   toward 
  the 
  idea 
  that 
  there 
  may 
  be 
  much 
  in 
  this 
  theory. 
  It 
  

   seems 
  very 
  probable 
  that 
  the 
  true 
  explanation 
  will 
  be 
  obtained 
  by 
  

   combining 
  Cook's 
  and 
  Olchewsky's 
  theory. 
  

  

  Interiocking 
  of 
  the 
  grains 
  no 
  doubt 
  has 
  much 
  to 
  do 
  with 
  the 
  

   tenacity 
  exhibited 
  by 
  highly 
  plastic 
  clays, 
  but 
  the 
  gliding 
  of 
  the 
  

   particles 
  is 
  probably 
  explained 
  by 
  the 
  circumstance 
  that 
  such 
  

   movement 
  offers 
  the 
  least 
  resistance 
  to 
  surface 
  tension. 
  

  

  Tensile 
  strength, 
  however, 
  seems 
  to 
  be 
  more 
  affected 
  by 
  size 
  of 
  

   grain 
  than 
  plasticity 
  is. 
  Fine-grained 
  clays 
  seldom 
  show 
  high 
  

   tensile 
  strength, 
  whereas 
  some 
  fine-grained 
  clays 
  show 
  high 
  plas- 
  

   ticity. 
  That 
  a 
  certain 
  relation 
  appears 
  to 
  exist 
  between 
  plasticity 
  

   and 
  tensile 
  strength, 
  and 
  that 
  the 
  former 
  does 
  not 
  necessarily 
  in- 
  

   crease 
  with 
  the 
  amount 
  of 
  kaolinite 
  (or 
  indirectly 
  alumina) 
  pres- 
  

   ent 
  are 
  shown 
  by 
  the 
  following 
  tests 
  of 
  some 
  North 
  Carolina 
  

   clays. 
  

  

  Tensile 
  strength 
  In 
  

   pounds 
  per 
  sq. 
  in. 
  

   Per 
  cent 
  of 
  

   alumina 
  Averapre 
  Maximum 
  

  

  Roanoke 
  Rapids 
  plastic 
  clay 
  16. 
  09 
  206 
  218 
  

  

  Washed 
  kaolin 
  40 
  . 
  61 
  20 
  22 
  

  

  Spoutsprings 
  fine-grained 
  clay 
  32.51 
  24 
  29 
  

  

  While 
  this 
  relation 
  between 
  tensile 
  strength 
  and 
  plasticity 
  seems 
  

   to 
  hold 
  good 
  in 
  a 
  large 
  majority 
  of 
  clays, 
  still 
  it 
  can 
  not 
  be 
  said 
  

  

  • 
  Zap 
  imp. 
  rvssk 
  ter.hn. 
  obschtsch. 
  1896. 
  80, 
  pt 
  6-7. 
  

   ' 
  Missouri 
  geol. 
  sur. 
  1897 
  . 
  11: 
  10'<J. 
  

  

  