﻿144 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  194 
  3 
  

  

  although 
  the 
  absolute 
  figures 
  may 
  appear 
  insignificant 
  these 
  fluctua- 
  

   tions 
  may 
  have 
  a 
  strong 
  effect 
  on 
  the 
  population 
  of 
  the 
  sea. 
  Indeed, 
  

   this 
  is 
  subject 
  to 
  regular 
  cyclic 
  changes 
  very 
  pronounced 
  in 
  planktonic 
  

   forms. 
  

  

  The 
  annual 
  crop 
  of 
  plankton 
  depends 
  on 
  the 
  amount 
  of 
  phosphates 
  

   and 
  nitrates, 
  and 
  there 
  is 
  an 
  apparent 
  relation 
  beween 
  the 
  quantity 
  

   of 
  phosphate 
  available 
  at 
  the 
  beginning 
  of 
  each 
  year 
  and 
  the 
  number 
  

   of 
  young 
  fish 
  which 
  have 
  had 
  enough 
  food 
  and 
  survived 
  during 
  the 
  

   ensuing 
  summer 
  months. 
  In 
  temperate 
  seas 
  almost 
  all 
  these 
  salts 
  have 
  

   been 
  used 
  up 
  during 
  the 
  summer 
  and 
  continued 
  growth 
  depends 
  on 
  

   new 
  supplies 
  brought 
  up 
  from 
  below 
  by 
  vertical 
  mixing 
  caused 
  by 
  

   convection 
  currents 
  during 
  the 
  winter, 
  when 
  a 
  rather 
  thorough 
  re- 
  

   newal 
  takes 
  place. 
  

  

  The 
  annual 
  crop 
  of 
  plankton 
  depends 
  on 
  the 
  amount 
  of 
  phosphates 
  

   and 
  nitrates, 
  and 
  there 
  is 
  an 
  apparent 
  relation 
  between 
  the 
  quantity 
  of 
  

   phosphate 
  available 
  at 
  the 
  beginning 
  of 
  each 
  year 
  and 
  the 
  number 
  of 
  

   young 
  fish 
  which 
  have 
  had 
  enough 
  food 
  and 
  survived 
  during 
  the 
  ensu- 
  

   ing 
  summer 
  months. 
  In 
  temperate 
  seas 
  almost 
  all 
  these 
  salts 
  have 
  

   been 
  used 
  up 
  during 
  the 
  summer 
  and 
  continued 
  growth 
  depends 
  on 
  new 
  

   supplies 
  brought 
  up 
  from 
  below 
  by 
  vertical 
  mixing 
  caused 
  by 
  convec- 
  

   tion 
  currents 
  during 
  the 
  winter, 
  when 
  a 
  rather 
  thorough 
  renewal 
  takes 
  

   place. 
  

  

  SOFTENING 
  SEA 
  WATER 
  

  

  The 
  chemist 
  is 
  already 
  searching 
  for 
  materials 
  capable 
  of 
  selectively 
  

   absorbing 
  and 
  retaining 
  substances 
  present 
  in 
  small 
  quantities 
  in 
  

   large 
  volumes 
  of 
  water. 
  Such 
  base-exchanging 
  materials 
  are 
  widely 
  

   used 
  in 
  the 
  softening 
  of 
  hard 
  waters, 
  a 
  process 
  which 
  involves 
  the 
  

   replacement 
  of 
  soap-destroying 
  and 
  scale-forming 
  calcium 
  and 
  mag- 
  

   nesium 
  by 
  relatively 
  innnocuous 
  sodium. 
  Natural 
  zeolites 
  were 
  first 
  

   used 
  for 
  this 
  purpose 
  and 
  later 
  supplemented 
  by 
  artificial 
  zeolites 
  

   and 
  by 
  sulfonated 
  carbonaceous 
  materials. 
  These 
  last 
  offer 
  the 
  addi- 
  

   tional 
  advantage 
  of 
  replacing 
  the 
  calcium 
  or 
  magnesium 
  with 
  hydro- 
  

   gen 
  instead 
  of 
  sodium 
  if 
  desired. 
  In 
  this 
  way 
  the 
  dissolved 
  salts 
  can 
  

   be 
  removed 
  altogether 
  instead 
  of 
  merely 
  replaced. 
  Such 
  a 
  process 
  

   is 
  particularly 
  valuable 
  in 
  water 
  for 
  boilers. 
  They 
  are 
  made 
  by 
  treat- 
  

   ing 
  coal 
  or 
  lignite 
  with 
  strong 
  reagents 
  such 
  as 
  fuming 
  sulfuric 
  acid, 
  

   sulfur 
  trioxide, 
  chromic 
  acid, 
  etc. 
  The 
  active 
  group 
  in 
  these 
  zeolites 
  is 
  

   believed 
  to 
  be 
  a 
  sulfonic 
  acid 
  group. 
  

  

  Much 
  the 
  same 
  principle 
  explains 
  the 
  action 
  of 
  polyhydric 
  phenol 
  

   formaldehyde 
  resins. 
  These 
  contain 
  hydrogen 
  (in 
  an 
  hydroxyl 
  group) 
  

   which 
  readily 
  goes 
  into 
  solution 
  to 
  replace 
  calcium 
  or 
  sodium 
  ions 
  

   and 
  forms 
  acids. 
  Such 
  resins 
  are 
  reported 
  as 
  physically 
  more 
  stable 
  

   and 
  faster 
  in 
  action 
  than 
  the 
  other 
  softeners 
  mentioned. 
  There 
  is 
  

   another 
  group 
  of 
  resins 
  described 
  as 
  amine- 
  formaldehyde, 
  which 
  

  

  