﻿THE 
  SEA 
  AS 
  A 
  STOREHOUSE 
  — 
  ARMSTRONG 
  143 
  

  

  received 
  all 
  the 
  time 
  from 
  the 
  land 
  and 
  returned, 
  as 
  we 
  shall 
  see, 
  to 
  the 
  

   bottom 
  of 
  the 
  ocean. 
  

  

  Analyses 
  of 
  sea 
  water 
  showing 
  the 
  amount 
  of 
  the 
  rarer 
  minerals 
  

   are 
  so 
  far 
  scanty, 
  and 
  it 
  cannot, 
  for 
  example, 
  be 
  said 
  that 
  a 
  particular 
  

   compound 
  is 
  present 
  everywhere 
  to 
  the 
  same 
  extent. 
  Evidence 
  is 
  

   also 
  lacking 
  whether 
  some 
  of 
  them 
  are 
  accumulating 
  or 
  whether 
  they 
  

   are 
  being 
  deposited 
  either 
  as 
  such 
  or 
  after 
  absorption 
  into 
  the 
  struc- 
  

   ture 
  of 
  some 
  marine 
  organism. 
  The 
  occurrence 
  of 
  minerals 
  in 
  veins 
  

   or 
  lodes 
  in 
  sedimentary 
  rocks 
  gives 
  support 
  to 
  the 
  idea 
  of 
  deposition. 
  

   Moreover, 
  the 
  vast 
  deposits 
  of 
  limestone 
  and 
  chalk 
  so 
  characteristic 
  

   of 
  southern 
  England 
  are 
  all 
  derived 
  from 
  organisms 
  which 
  have 
  

   taken 
  up 
  the 
  traces 
  of 
  calcium 
  salts 
  from 
  the 
  sea. 
  Elsewhere 
  calcium 
  

   has 
  been 
  deposited 
  as 
  sulfate. 
  

  

  At 
  this 
  stage 
  therefore 
  one 
  can 
  state 
  purely 
  as 
  a 
  working 
  hypothesis 
  

   that 
  while 
  the 
  ocean 
  is 
  constant 
  in 
  composition 
  in 
  regard 
  to 
  its 
  main 
  

   constituents 
  it 
  is 
  variable 
  and 
  even 
  local 
  in 
  regard 
  to 
  the 
  trace 
  

   elements. 
  

  

  Quite 
  another 
  problem 
  is 
  the 
  fate 
  of 
  those 
  minerals 
  the 
  world 
  

   over 
  which 
  are 
  constantly 
  reaching 
  the 
  sea 
  either 
  from 
  sewage 
  or 
  by 
  

   the 
  leaching 
  out 
  of 
  cultivated 
  lands. 
  While 
  these 
  in 
  the 
  aggregate 
  

   total 
  far 
  less 
  than 
  what 
  is 
  produced 
  by 
  denudation, 
  they 
  are 
  of 
  im- 
  

   portance 
  because 
  they 
  represent 
  the 
  constituents 
  which 
  are 
  of 
  primary 
  

   value 
  to 
  man. 
  

  

  One 
  of 
  the 
  most 
  interesting 
  of 
  these 
  is 
  phosphate, 
  of 
  which 
  the 
  

   mineral 
  deposits 
  are 
  limited 
  in 
  amount 
  and 
  may 
  well 
  become 
  ex- 
  

   hausted. 
  Many 
  of 
  the 
  agricultural 
  soils 
  of 
  the 
  world 
  are 
  definitely 
  

   short 
  of 
  phosphates 
  and 
  their 
  crop-bearing 
  qualities 
  impaired 
  in 
  

   consequence. 
  A 
  new 
  widely 
  distributed 
  source 
  of 
  phosphate 
  would 
  

   therefore 
  be 
  of 
  great 
  value 
  and 
  importance. 
  

  

  It 
  has 
  been 
  calculated 
  that 
  the 
  sewage 
  from 
  5 
  million 
  people 
  is 
  

   equivalent 
  to 
  17,000 
  tons 
  of 
  rock 
  phosphate 
  in 
  a 
  year, 
  and 
  this 
  happens 
  

   to 
  be 
  the 
  quantity 
  present 
  in 
  the 
  annual 
  export 
  of 
  meat 
  from 
  New 
  

   Zealand, 
  which 
  Dominion 
  is 
  the 
  loser 
  of 
  the 
  same 
  amount. 
  The 
  popu- 
  

   lation 
  of 
  Great 
  Britain 
  discards 
  as 
  sewage 
  the 
  equivalent 
  of 
  150,000 
  

   tons 
  of 
  rock 
  phosphate, 
  most 
  of 
  which 
  reaches 
  the 
  sea. 
  An 
  estimate 
  

   of 
  the 
  annual 
  losses 
  of 
  phosphate 
  from 
  all 
  sources 
  to 
  the 
  sea 
  in 
  the 
  

   United 
  States 
  amounts 
  to 
  the 
  equivalent 
  of 
  60 
  million 
  tons 
  of 
  rock. 
  

   The 
  world's 
  consumption 
  of 
  phosphate 
  rock 
  is 
  said 
  to 
  be 
  18 
  million 
  

   tons; 
  there 
  are 
  of 
  course 
  other 
  sources 
  of 
  phosphatic 
  fertilizers. 
  

  

  The 
  question 
  may 
  well 
  be 
  asked, 
  what 
  is 
  happening 
  to 
  the 
  phos- 
  

   phate; 
  is 
  it 
  being 
  concentrated 
  and 
  removed 
  or 
  deposited? 
  Here 
  is 
  

   an 
  interesting 
  problem 
  for 
  study. 
  The 
  concentrations 
  of 
  nitrates, 
  

   phosphates, 
  and 
  silicates 
  in 
  sea 
  water 
  are 
  subject 
  to 
  considerable 
  

   fluctuation 
  depending 
  on 
  the 
  activity 
  of 
  the 
  marine 
  organisms, 
  and 
  

  

  