﻿AGE 
  OF 
  THE 
  EARTH— 
  CHAMBERLIN 
  AND 
  OTHERS. 
  257 
  

  

  made 
  as 
  promptly 
  as 
  possible 
  after 
  the 
  sample 
  tube 
  had 
  taken 
  the 
  

   soil 
  from 
  its 
  natural 
  relations. 
  21 
  At 
  the 
  sea 
  end 
  of 
  the 
  cycle 
  the 
  

   recombinations 
  of 
  the 
  acid 
  radicals 
  with 
  the 
  basic 
  radicals 
  seems 
  to 
  

   take 
  place 
  chiefly 
  at 
  the 
  base 
  of 
  the 
  turbid 
  water 
  as 
  it 
  is 
  carried 
  out 
  

   over 
  the 
  concentrated 
  sea 
  solutions 
  and 
  diffuses 
  into 
  them. 
  Before 
  

   the 
  acid 
  radicals 
  reach 
  the 
  bottom 
  the 
  reversing 
  phase 
  of 
  the 
  cycle 
  

   has 
  probably 
  ended 
  and 
  a 
  new 
  cycle 
  begun 
  under 
  suboceanic 
  condi- 
  

   tions. 
  The 
  experimental 
  evidence 
  in 
  support 
  of 
  this 
  conclusion 
  is 
  

   buried 
  in 
  a 
  great 
  mass 
  of 
  literature 
  which 
  relates 
  primarily 
  to 
  other 
  

   elements, 
  particularly 
  the 
  elements 
  that 
  form 
  plant 
  foods, 
  such 
  as 
  

   potassium, 
  phosphorus, 
  etc., 
  and 
  those 
  that 
  form 
  precipitates 
  such 
  

   as 
  calcium 
  and 
  magnesium 
  carbonates, 
  but 
  when 
  these 
  scattered 
  data 
  

   are 
  gathered 
  together 
  their 
  combined 
  import 
  is 
  sufficient 
  to 
  make 
  

   clear 
  the 
  essentials 
  of 
  what 
  happens. 
  22 
  

  

  The 
  present 
  status 
  of 
  knowledge 
  and 
  opinion 
  is 
  summarized 
  by 
  

   the 
  following 
  quotations. 
  

  

  Doctor 
  Truog 
  writes 
  : 
  23 
  

  

  The 
  minerals 
  or 
  salts 
  in 
  soils 
  consist 
  largely 
  of 
  silicates. 
  On 
  weathering 
  

   the 
  bases 
  are 
  removed 
  from 
  the 
  silicates, 
  leaving 
  acid 
  residues 
  or 
  acid 
  silicates. 
  

   These 
  acid 
  silicates 
  will 
  react 
  with 
  salts 
  like 
  KC1 
  and 
  NaCl 
  and 
  remove 
  the 
  

   base 
  and 
  leave 
  HC1 
  in 
  solution. 
  When 
  soil 
  is 
  treated 
  with 
  equal 
  molecular 
  

   strengths 
  of 
  these 
  two 
  solutions, 
  the 
  potassium 
  is 
  removed 
  to 
  a 
  greater 
  ex- 
  

   tent 
  than 
  the 
  sodium. 
  This 
  is 
  due 
  to 
  the 
  fact 
  that 
  the 
  potassium 
  forms 
  more 
  

   insoluble 
  compounds 
  with 
  the 
  acid 
  silicates 
  than 
  the 
  sodium. 
  Furthermore, 
  

   silicates 
  which 
  have 
  not 
  had 
  their 
  bases 
  removed 
  will 
  also 
  react 
  with 
  these 
  

   salts 
  and 
  exchange 
  bases 
  with 
  them. 
  For 
  example, 
  potassium 
  chloride 
  will 
  

   react 
  with 
  an 
  insoluble 
  sodium 
  silicate, 
  in 
  which 
  reaction 
  the 
  potassium 
  replaces 
  

   the 
  sodium 
  and 
  the 
  sodium 
  is 
  left 
  in 
  solution 
  as 
  soluble 
  sodium 
  chloride. 
  If 
  an 
  

   insoluble 
  potassium 
  silicate 
  were 
  treated 
  with 
  a 
  solution 
  of 
  sodium 
  chloride, 
  

   some 
  of 
  the 
  sodium 
  would 
  replace 
  the 
  potassium 
  and 
  some 
  potassium 
  would 
  

   thus 
  go 
  into 
  solution 
  as 
  the 
  soluble 
  chloride. 
  This, 
  however, 
  would 
  not 
  proceed 
  

   to 
  as 
  great 
  an 
  extent 
  as 
  the 
  previous 
  reaction, 
  since 
  the 
  potassium 
  forms 
  a 
  

   more 
  insoluble 
  silicate 
  than 
  sodium. 
  In 
  reading 
  some 
  of 
  the 
  literature 
  on 
  this 
  

   subject 
  one 
  may 
  get 
  the 
  impression 
  that 
  sodium 
  is 
  not 
  retained 
  by 
  soils 
  like 
  

   the 
  potassium, 
  but 
  this 
  is 
  really 
  not 
  the 
  case; 
  the 
  action 
  is 
  merely 
  relative. 
  

   The 
  potassium 
  is 
  retained 
  to 
  a 
  greater 
  extent 
  simply 
  because 
  it 
  forms 
  more 
  

   insoluble 
  compounds 
  with 
  the 
  soils. 
  

  

  » 
  Bull. 
  26, 
  U. 
  S. 
  Dept. 
  Agri. 
  (1905), 
  pp. 
  26-27. 
  

  

  Zi 
  The 
  following 
  are 
  among 
  the 
  more 
  important 
  early 
  investigations 
  : 
  

  

  Way, 
  Jour. 
  Roy. 
  Agri. 
  Soc, 
  vol. 
  11 
  (1850), 
  pp. 
  313-379; 
  vol. 
  13 
  (1852), 
  pp. 
  123-143: 
  

   vol. 
  15 
  (1854), 
  p. 
  491. 
  

  

  Eichhorn, 
  Pogg.-An., 
  vol. 
  125 
  (1854). 
  p. 
  126. 
  

  

  Voelcker, 
  Jour. 
  Roy. 
  Agri. 
  Soc, 
  2d 
  series, 
  vol. 
  I, 
  pp. 
  289-316. 
  

  

  Kullenberg, 
  Hoffman's 
  "Jahres 
  bericht 
  der 
  Agrikulrur 
  Chemie," 
  vol. 
  8 
  (1865), 
  p. 
  15. 
  

  

  Lemberg, 
  Zeitschr. 
  deutsch. 
  Geol. 
  Gesell., 
  vol. 
  29 
  (1877), 
  p. 
  483. 
  

  

  28 
  E. 
  Truog, 
  soil 
  chemist. 
  Dept. 
  of 
  Soils 
  of 
  the 
  College 
  of 
  Agriculture, 
  University 
  of 
  

   Wisconsin. 
  Personal 
  communication. 
  

  

  