﻿138 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  quantity 
  arose 
  out 
  of 
  the 
  search 
  for 
  substances 
  which 
  could 
  be 
  added 
  

   to 
  petrol 
  to 
  prevent 
  the 
  engines 
  of 
  automobiles 
  knocking. 
  Midgley 
  

   solved 
  this 
  problem 
  with 
  a 
  chemical 
  known 
  as 
  tetraethyl 
  lead 
  dissolved 
  

   in 
  ethylene 
  bromide 
  — 
  the 
  substance 
  marketed 
  as 
  "Ethyl." 
  At 
  once 
  

   very 
  large 
  quantities 
  of 
  bromine 
  were 
  needed, 
  and 
  a 
  new 
  cheap 
  source 
  

   out 
  of 
  the 
  control 
  of 
  the 
  monopoly 
  had 
  to 
  be 
  found. 
  

  

  Work 
  was 
  begun 
  in 
  1924 
  by 
  a 
  process 
  which 
  involved 
  the 
  addition 
  

   of 
  aniline 
  to 
  chlorinated 
  sea 
  water 
  to 
  form 
  tribromoaniline. 
  After 
  

   laboratory 
  trials 
  the 
  process 
  was 
  operated 
  on 
  board 
  a 
  boat, 
  the 
  S. 
  S. 
  

   Ethyl, 
  fitted 
  out 
  as 
  a 
  chemical 
  factory. 
  

  

  This 
  sailed 
  off 
  the 
  coast 
  of 
  North 
  Carolina 
  and 
  the 
  voyage 
  was 
  

   successful 
  though 
  it 
  was 
  not 
  repeated. 
  The 
  experience 
  gained 
  was 
  

   applied 
  to 
  an 
  alternative 
  method 
  which 
  consists 
  in 
  (a) 
  oxidizing 
  

   the 
  bromide 
  in 
  brine 
  with 
  clorine, 
  (b) 
  blowing 
  the 
  free 
  bromine 
  out 
  

   of 
  solution 
  with 
  air, 
  (c) 
  absorbing 
  the 
  bromine 
  with 
  an 
  alkali 
  car- 
  

   bonate 
  solution 
  from 
  which 
  it 
  can 
  be 
  recovered 
  in 
  a 
  commercially 
  

   desirable 
  form. 
  

  

  Every 
  stage 
  in 
  this 
  process 
  had 
  to 
  be 
  carefully 
  worked 
  out 
  in 
  the 
  lab- 
  

   oratory. 
  Sea 
  water 
  is 
  alkaline, 
  the 
  equivalent 
  of 
  1 
  ounce 
  of 
  caustic 
  

   soda 
  in 
  1,000 
  tons 
  of 
  water. 
  Even 
  this 
  small 
  quantity 
  gives 
  con- 
  

   ditions 
  unsuitable 
  to 
  the 
  oxidation. 
  Acid 
  must 
  be 
  added, 
  the 
  right 
  

   quantity 
  being 
  0.27 
  pound 
  of 
  96 
  percent 
  sulfuric 
  acid 
  per 
  ton 
  of 
  sea 
  

   water. 
  These 
  figures 
  are 
  quoted 
  to 
  show 
  the 
  layman 
  how 
  sensitive 
  

   chemical 
  reactions 
  are 
  to 
  small 
  things, 
  in 
  particular 
  to 
  the 
  acid-alkali 
  

   reaction 
  of 
  the 
  medium. 
  The 
  biochemist 
  has 
  of 
  late 
  years 
  discovered 
  

   that 
  the 
  reactions 
  in 
  the 
  living 
  body 
  are 
  even 
  more 
  sensitive 
  to 
  these 
  

   acid-alkali 
  variations. 
  

  

  The 
  conditions 
  of 
  the 
  operations 
  having 
  been 
  settled 
  by 
  the 
  chemist, 
  

   the 
  next 
  step 
  is 
  for 
  the 
  engineer 
  to 
  design 
  a 
  plant 
  (a) 
  to 
  carry 
  out 
  the 
  

   chemical 
  changes, 
  ( 
  b 
  ) 
  to 
  bring 
  the 
  water 
  from 
  the 
  sea 
  in 
  the 
  required 
  

   large 
  quantity. 
  

  

  It 
  requires 
  4,000 
  gallons 
  of 
  sea 
  water 
  to 
  yield 
  1 
  pound 
  of 
  bromine, 
  so 
  

   that 
  a 
  factory 
  making 
  15,000 
  pounds 
  a 
  day 
  must 
  be 
  able 
  to 
  pump 
  60 
  

   million 
  gallons. 
  The 
  engineering 
  problem 
  of 
  the 
  intake 
  of 
  such 
  quan- 
  

   tities, 
  the 
  freeing 
  of 
  the 
  water 
  from 
  extraneous 
  matter 
  and 
  sedi- 
  

   ment 
  and 
  its 
  delivery 
  continuously 
  to 
  the 
  plant, 
  all 
  at 
  low 
  cost, 
  has 
  

   been 
  one 
  of 
  the 
  first 
  magnitude 
  ; 
  it 
  required 
  great 
  ingenuity 
  and 
  fore- 
  

   sight. 
  It 
  is 
  clear 
  that 
  it 
  would 
  not 
  do 
  to 
  put 
  the 
  extracted 
  water 
  back 
  

   in 
  the 
  sea. 
  It 
  has 
  to 
  be 
  discharged 
  some 
  way 
  off, 
  for 
  example, 
  on 
  the 
  

   other 
  side 
  of 
  an 
  isthmus 
  where 
  the 
  set 
  of 
  the 
  currents 
  prevents 
  its 
  

   mixing 
  with 
  the 
  untreated 
  incoming 
  water. 
  Obviously 
  the 
  choice 
  of 
  

   location 
  of 
  a 
  sea-water 
  plant 
  is 
  both 
  all-important 
  and 
  limited. 
  

  

  When 
  the 
  operations 
  are 
  all 
  finished 
  the 
  bromine 
  is 
  obtained 
  in 
  

   liquid 
  form. 
  Its 
  transport 
  requires 
  special 
  bottles 
  and 
  is 
  costly. 
  It 
  

   is 
  therefore 
  at 
  once 
  converted 
  on 
  the 
  same 
  site 
  into 
  ethylene 
  bromide. 
  

  

  