﻿112 
  J. 
  A. 
  PHILLIPS 
  ON 
  THE 
  EED 
  SANDS 
  

  

  Silica 
  98-53- 
  

  

  Protoxide 
  of 
  Iron 
  0-28 
  

  

  Alumina 
  0*88 
  

  

  Lime, 
  Magnesia, 
  and 
  Alkalies 
  traces. 
  

  

  99-69 
  

  

  It 
  follows, 
  therefore, 
  not 
  only 
  that 
  the 
  external 
  coating 
  of 
  ferric 
  

   oxide 
  must 
  have 
  been 
  deposited 
  subsequently 
  to 
  the 
  rounding 
  of 
  

   the 
  sand, 
  but 
  also 
  that 
  it 
  could 
  not 
  have 
  been 
  derived 
  from 
  an 
  ex- 
  

   ternal 
  decomposition 
  of 
  the 
  grains 
  themselves, 
  since 
  the 
  total 
  amount 
  

   of 
  iron 
  which 
  they 
  contain 
  scarcely 
  exceeds 
  that 
  removed 
  from 
  their 
  

   surfaces 
  by 
  digestion 
  in 
  dilute 
  acid. 
  

  

  Seeing 
  that 
  the 
  oxide 
  of 
  iron 
  cannot 
  have 
  been 
  the 
  result 
  of 
  

   chemical 
  action 
  upon 
  the 
  sands 
  themselves, 
  it 
  becomes 
  somewhat 
  

   difficult 
  to 
  imagine 
  whence 
  it 
  can 
  have 
  been 
  derived. 
  The 
  

   rounded 
  grains 
  covered 
  by 
  a 
  coating 
  of 
  iron 
  oxide, 
  readily 
  removed 
  

   by 
  hydrochloric 
  acid, 
  exactly 
  resemble 
  those 
  of 
  some 
  of 
  the 
  " 
  millet- 
  

   sandstones" 
  of 
  Triassic 
  age. 
  In 
  the 
  latter 
  instance, 
  however, 
  the 
  

   iron 
  has 
  doubtless 
  been 
  deposited 
  either 
  during 
  a 
  period 
  of 
  sub- 
  

   mergence 
  or 
  subsequently 
  by 
  percolation 
  from 
  overlying 
  strata, 
  

   both 
  of 
  which 
  conditions 
  would, 
  in 
  the 
  case 
  of 
  the 
  rTefud, 
  appear 
  to 
  

   be 
  improbable. 
  

  

  Discussion. 
  

  

  The 
  President 
  asked 
  if 
  any 
  one 
  present 
  was 
  prepared 
  to 
  offer 
  a 
  

   suggestion 
  as 
  to 
  the 
  origin 
  of 
  the 
  iron 
  coating 
  the 
  grains. 
  

  

  Rev. 
  A. 
  Ieving 
  suggested 
  that 
  vegetation 
  might 
  be 
  the 
  agency 
  

   by 
  which 
  the 
  iron 
  was 
  separated 
  and 
  deposited 
  on 
  the 
  sand 
  grains. 
  

  

  Mr. 
  Drew 
  pointed 
  out 
  that 
  the 
  action 
  of 
  vegetation 
  on 
  the 
  sands 
  

   of 
  the 
  Bagshot 
  beds 
  was 
  to 
  bleach, 
  and 
  not 
  to 
  colour 
  them 
  with 
  

   oxide 
  of 
  iron. 
  

  

  Prof. 
  Seeley 
  suggested 
  that 
  slight 
  solution 
  of 
  the 
  grains 
  might 
  

   have 
  taken 
  place 
  owing 
  to 
  the 
  constant 
  deposition 
  of 
  dew 
  on 
  these 
  

   sand 
  grains, 
  which 
  would 
  assist 
  in 
  rounding 
  them 
  and 
  leave 
  the 
  

   surface 
  coated 
  with 
  iron 
  oxide. 
  

  

  Prof. 
  Morris 
  said 
  that 
  in 
  few 
  of 
  the 
  old 
  sands 
  and 
  sandstones 
  

   were 
  the 
  quartz 
  grains 
  perfectly 
  rounded. 
  He 
  referred 
  to 
  some 
  

   crystalline 
  sandstones 
  of 
  Penrith, 
  and 
  suggested 
  that 
  they 
  might 
  be 
  

   derived 
  from 
  limestones, 
  in 
  which 
  such 
  crystals 
  are 
  often 
  developed. 
  

   Certain 
  French 
  geologists 
  have 
  suggested 
  an 
  eruptive 
  origin 
  for 
  some 
  

   Tertiary 
  sands 
  in 
  which 
  also 
  prisms 
  of 
  quartz 
  occur. 
  

  

  Dr. 
  Hicks 
  pointed 
  out 
  that 
  in 
  nearly 
  all 
  the 
  old 
  rocks 
  most 
  of 
  the 
  

   grains 
  were 
  but 
  slightly 
  rounded, 
  and 
  some 
  tolerably 
  perfect 
  crystals 
  

   also 
  were 
  generally 
  present. 
  

  

  Mr. 
  Phillips 
  said 
  that 
  the 
  most 
  remarkable 
  thing 
  about 
  the 
  sand 
  

  

  * 
  The 
  amount 
  of 
  material 
  at 
  my 
  disposal 
  was 
  not 
  sufficiently 
  large 
  to 
  admit 
  

   of 
  the 
  estimation 
  of 
  substances 
  present 
  in 
  very 
  small 
  quantities 
  only. 
  

  

  