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  Galloway 
  — 
  Rounding 
  of 
  Sand 
  by 
  Solution. 
  

  

  same 
  law 
  accounts 
  for 
  the 
  dissolving 
  off 
  of 
  corners, 
  for 
  

   the 
  more 
  irregular 
  the 
  shape 
  the 
  greater 
  the 
  surface 
  in 
  

   proportion 
  to 
  volume. 
  

  

  A 
  sample 
  of 
  very 
  fine 
  sand 
  from 
  a 
  bubbling 
  spring 
  at 
  

   Dayton, 
  Maine, 
  consists 
  of 
  quartz, 
  fresh 
  feldspar, 
  horn- 
  

   blende 
  and 
  biotite 
  grains, 
  all 
  between 
  -04 
  and 
  -15 
  mm. 
  in 
  

   diameter, 
  many 
  of 
  which 
  are 
  round 
  or 
  subround. 
  The 
  

  

  Fig. 
  4. 
  

  

  Fig. 
  4. 
  Grains 
  of 
  common 
  table 
  salt 
  rounded 
  by 
  solution 
  in 
  water. 
  The 
  

   smaller 
  grains 
  are 
  the 
  most 
  nearly 
  round. 
  Grains 
  seen 
  in 
  water 
  by 
  trans- 
  

   mitted 
  light. 
  X 
  50. 
  

  

  smallest 
  grains 
  are 
  the 
  most 
  nearly 
  round, 
  which 
  shows 
  

   that 
  solution 
  was 
  the 
  main 
  factor 
  in 
  the 
  process 
  of 
  round- 
  

   ing 
  them. 
  The 
  smallest 
  perfectly 
  round 
  grain 
  measured 
  

   was 
  of 
  quartz 
  which 
  was 
  -04 
  mm. 
  in 
  diameter. 
  If 
  the 
  

   rounding 
  has 
  been 
  due 
  entirely 
  to 
  mechanical 
  action, 
  

   either 
  by 
  wind 
  or 
  water, 
  the 
  largest 
  grains 
  would 
  have 
  

   been 
  rounded 
  most, 
  Flakes 
  of 
  biotite 
  -1 
  mm. 
  and 
  over 
  

   were 
  also 
  round 
  and 
  were 
  undoubtedly 
  so 
  formed 
  by 
  abra- 
  

   sion 
  in 
  the 
  feeble 
  spring. 
  The 
  surfaces 
  of 
  the 
  rounded 
  

   grains 
  of 
  quartz 
  and 
  feldspar 
  were 
  perfectly 
  smooth, 
  with 
  

   an 
  oily 
  luster, 
  the 
  most 
  brilliant 
  surfaces 
  I 
  have 
  ever 
  seen 
  

  

  