﻿256 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  The 
  mud 
  cycle 
  actuated 
  by 
  the 
  surface 
  foods. 
  — 
  Familiar 
  as 
  this 
  is 
  

   in 
  many 
  respects, 
  it 
  has 
  perhaps 
  received 
  less 
  critical 
  geochemical 
  

   study 
  than 
  almost 
  any 
  other 
  common 
  feature 
  of 
  nature 
  with 
  which 
  

   we 
  are 
  directly, 
  not 
  to 
  say 
  unpleasantly, 
  brought 
  into 
  contact. 
  The 
  

   agricultural 
  chemists 
  have 
  naturally 
  been 
  preoccupied 
  with 
  those 
  

   elements 
  of 
  the 
  soils 
  that 
  serve 
  as 
  plant 
  food, 
  the 
  students 
  of 
  hygiene 
  

   and 
  domestic 
  science 
  with 
  waters 
  suitable 
  for 
  drinking 
  and 
  culinary 
  

   purposes, 
  and 
  the 
  geologic 
  chemists 
  with 
  the 
  organic 
  extracts 
  and 
  

   precipitates 
  that 
  form 
  the 
  limestones, 
  dolomites, 
  and 
  siliceous 
  beds. 
  

   The 
  mud 
  factor 
  of 
  the 
  surface 
  wash 
  has 
  been 
  neglected. 
  And 
  yet 
  

   the 
  muds 
  (later 
  shales) 
  comprise 
  much 
  the 
  largest 
  part 
  of 
  the 
  solid 
  

   residue 
  of 
  disintegration. 
  This 
  solid 
  disaggregated 
  residue 
  and 
  the 
  

   colloids 
  associated 
  with 
  it 
  are 
  separated 
  from 
  the 
  true 
  solutions 
  in 
  

   large 
  measure 
  at 
  the 
  very 
  start 
  on 
  their 
  long 
  journey 
  to 
  the 
  sea. 
  

   The 
  true 
  solutions 
  are 
  largely 
  formed 
  by 
  waters 
  that 
  descend 
  through 
  

   the 
  soils 
  into 
  the 
  underlying 
  formations 
  and 
  thus 
  form 
  the 
  ground 
  

   waters 
  which 
  pass 
  by 
  springs 
  and 
  seep 
  into 
  the 
  streams, 
  giving 
  them 
  

   their 
  steady 
  supply 
  of 
  clear 
  water. 
  This 
  is 
  the 
  water 
  chiefly 
  analyzed 
  

   and 
  taken 
  into 
  account 
  in 
  reckoning 
  the 
  material 
  borne 
  by 
  the 
  streams 
  

   to 
  the 
  ocean. 
  The 
  solid 
  residue, 
  the 
  clays, 
  silts, 
  and 
  sands, 
  however, 
  

   are 
  only 
  slightly 
  removed 
  by 
  the 
  gentler 
  rains 
  which 
  soak 
  into 
  the 
  

   ground. 
  They 
  are 
  carried 
  down 
  to 
  sea 
  chiefly 
  by 
  the 
  floods 
  following 
  

   heavy 
  storms, 
  or 
  by 
  the 
  thaw 
  waters 
  of 
  winter 
  snows 
  which 
  form 
  the 
  

   spring 
  freshets, 
  or 
  by 
  flood 
  stages 
  from 
  any 
  cause. 
  The 
  turbid 
  mat- 
  

   ter 
  of 
  these 
  muddy 
  waters 
  contains 
  a 
  large 
  part 
  of 
  the 
  acid 
  radicals 
  

   with 
  which 
  the 
  basic 
  radicals 
  of 
  the 
  true 
  solutions 
  were 
  united 
  in 
  the 
  

   parent 
  rock 
  and 
  in 
  the 
  soils. 
  While 
  it 
  is 
  known 
  that 
  the 
  muddy 
  

   waters 
  contain 
  hydrous 
  silicates 
  of 
  alumina 
  and 
  iron, 
  partly 
  colloidal 
  

   and 
  partly 
  noncolloidal, 
  together 
  with 
  finely 
  divided 
  siliceous 
  silts 
  

   and 
  colloidal 
  silica, 
  full 
  and 
  exact 
  information 
  is 
  lacking. 
  Doctor 
  

   Collins 
  says 
  that 
  " 
  the 
  dissemination 
  of 
  silica 
  in 
  natural 
  waters, 
  par- 
  

   ticularly 
  turbid 
  waters, 
  is 
  one 
  of 
  the 
  least 
  accurately 
  known 
  of 
  the 
  de- 
  

   terminations 
  of 
  substances 
  present 
  in 
  appreciable 
  quantities." 
  20 
  He 
  

   adds 
  that 
  even 
  " 
  the 
  exact 
  state 
  of 
  the 
  silica 
  present 
  in 
  a 
  perfectly 
  clear 
  

   water 
  is 
  usually 
  not 
  known. 
  It 
  may 
  be 
  colloidal 
  or 
  it 
  may 
  be 
  present 
  

   as 
  a 
  silicate 
  radical." 
  In 
  addition 
  to 
  this 
  — 
  or 
  perhaps 
  the 
  cause 
  of 
  

   it 
  — 
  investigation 
  is 
  embarrassed 
  at 
  the 
  inland 
  end 
  of 
  the 
  cycle 
  by 
  the 
  

   fleeting 
  and 
  irregular 
  nature 
  of 
  the 
  freshet 
  stage, 
  and 
  by 
  the 
  rapid 
  

   and 
  intricate 
  changes 
  within 
  the 
  soils. 
  The 
  changes 
  in 
  the 
  soil 
  are 
  

   so 
  rapid 
  in 
  certain 
  respects 
  that 
  F. 
  H. 
  King 
  found 
  it 
  important 
  to 
  

   make 
  his 
  determinations 
  of 
  water-soluble 
  solutions 
  by 
  means 
  of 
  an 
  

   improvised 
  laboratory 
  in 
  the 
  field 
  so 
  that 
  determinations 
  might 
  be 
  

  

  -° 
  W. 
  E. 
  Collins, 
  chief 
  of 
  the 
  quality 
  of 
  water 
  division, 
  U. 
  S. 
  Geol. 
  Surv. 
  Personal 
  

   uouiniunicatiou. 
  

  

  