﻿AS 
  A 
  SOURCE 
  OF 
  THE 
  NITROGEN 
  FOUND 
  IN 
  PLANTS. 
  593 
  

  

  cause 
  of 
  the 
  delay 
  which 
  attended 
  the 
  announcement 
  that 
  water 
  is 
  not 
  a 
  simple 
  

   body. 
  Cavendish's 
  later 
  experiments 
  were 
  repeated 
  by 
  a 
  Committee 
  of 
  the 
  

   Royal 
  Society 
  at 
  his 
  own 
  request, 
  and 
  with 
  entire 
  success 
  ;* 
  and 
  if 
  any 
  one 
  is 
  slow 
  

   to 
  repose 
  faith 
  in 
  chemical 
  experiments 
  made 
  in 
  1785, 
  let 
  me 
  remind 
  him 
  that 
  

   Faraday 
  has 
  shewn 
  that 
  every 
  time 
  a 
  friction 
  electric 
  machine 
  is 
  in 
  action, 
  the 
  

   truth 
  of 
  Cavendish's 
  observations 
  may 
  be 
  proved, 
  by 
  no 
  more 
  complex 
  device 
  

   than 
  the 
  stretching 
  of 
  a 
  piece 
  of 
  paper 
  wetted 
  with 
  solution 
  of 
  potass, 
  across 
  the 
  

   interval 
  separating 
  two 
  surfaces, 
  between 
  which 
  electric 
  sparks 
  are 
  passing. 
  The 
  

   potass 
  is 
  quickly 
  changed 
  into 
  nitrate 
  of 
  potass, 
  f 
  

  

  Resting 
  upon 
  these 
  observations 
  of 
  Cavendish 
  and 
  Faraday, 
  I 
  urge 
  the 
  con- 
  

   clusion, 
  that 
  every 
  lightning 
  flash 
  must 
  convert 
  a 
  portion 
  of 
  the 
  air 
  into 
  nitric 
  

   acid 
  ; 
  and 
  that 
  in 
  tropical 
  regions 
  where 
  thunder-storms 
  prevail, 
  this 
  acid 
  must 
  

   be 
  produced 
  largely 
  and 
  almost 
  constantly. 
  

  

  Secondly, 
  As 
  for 
  the 
  proposition 
  that 
  the 
  ammonia 
  of 
  the 
  atmosphere 
  is 
  con- 
  

   verted 
  by 
  simple 
  oxidation, 
  as 
  in 
  the 
  process 
  of 
  nitrification 
  at 
  the 
  surface 
  of 
  the 
  

   earth, 
  into 
  nitric 
  acid, 
  I 
  might 
  leave 
  it 
  unconsidered, 
  for 
  my 
  concern 
  is 
  simply 
  

   with 
  nitric 
  acid, 
  not 
  with 
  its 
  source. 
  I 
  am 
  quite 
  prepared 
  to 
  admit 
  the 
  probabi- 
  

   lity 
  of 
  atmospheric 
  ammonia 
  undergoing 
  conversion 
  into 
  nitric 
  acid 
  ; 
  for 
  although 
  

   one 
  condition 
  essential 
  to 
  nitrification 
  in 
  the 
  soil, 
  namely, 
  the 
  presence 
  of 
  an 
  

   alkali 
  or 
  alkaline 
  earth 
  is 
  wanting, 
  yet, 
  from 
  what 
  is 
  known 
  of 
  the 
  intense 
  oxid- 
  

   ising 
  power 
  of 
  ozone, 
  we 
  may 
  well 
  believe 
  that 
  when 
  it 
  is 
  developed 
  in 
  the 
  air, 
  

   as 
  it 
  so 
  certainly 
  and 
  frequently 
  is, 
  it 
  will 
  compel 
  the 
  conversion 
  of 
  ammonia 
  

   into 
  nitric 
  acid. 
  It 
  will 
  presently, 
  indeed, 
  appear, 
  that, 
  from 
  the 
  recent 
  researches 
  

   of 
  Barral, 
  it 
  is 
  probable 
  that 
  nitric 
  acid 
  is 
  generated 
  in 
  the 
  atmosphere 
  at 
  the 
  

   expense 
  of 
  ammonia. 
  If 
  this, 
  however, 
  be 
  the 
  case, 
  then 
  we 
  must 
  acknowledge 
  

   that, 
  in 
  addition 
  to 
  thunder-storms, 
  a 
  force 
  is 
  constantly 
  at 
  work 
  in 
  the 
  air 
  pro- 
  

   ducing 
  nitric 
  acid 
  ; 
  and 
  further, 
  that 
  this 
  force 
  is 
  constantly 
  removing 
  from 
  the 
  

   atmosphere 
  the 
  ammonia 
  on 
  which 
  plants 
  are 
  supposed 
  to 
  be 
  solely 
  dependent 
  

   for 
  nitrogen. 
  

  

  No 
  data 
  exist 
  from 
  which 
  we 
  can 
  compute, 
  with 
  even 
  an 
  approximation 
  to 
  

   accuracy, 
  the 
  amount 
  of 
  nitric 
  acid 
  produced 
  by 
  thunder-storms 
  all 
  the 
  world 
  

   over. 
  It 
  is 
  certainly, 
  however, 
  considerable, 
  as 
  compared 
  with 
  the 
  amount 
  of 
  

   ammonia 
  in 
  air, 
  and 
  with 
  the 
  amount 
  of 
  nitrogen 
  required 
  by 
  plants. 
  

  

  It 
  is 
  further 
  uncertain 
  how 
  far 
  temperate 
  regions 
  profit 
  by 
  the 
  nitric 
  acid 
  

   developed 
  by 
  the 
  storms 
  of 
  tropical 
  latitudes 
  ; 
  but 
  from 
  the 
  known 
  effects 
  of 
  the 
  

   winds, 
  and 
  of 
  the 
  diffusive 
  force 
  of 
  gases, 
  in 
  spreading 
  through 
  the 
  atmosphere 
  

   substances 
  added 
  to 
  one 
  part 
  of 
  it, 
  we 
  cannot 
  doubt 
  that 
  when 
  the 
  heavy 
  rains 
  

   which 
  so 
  frequently 
  follow 
  thunder-storms, 
  do 
  not 
  at 
  once 
  transfer 
  to 
  the 
  earth 
  

   the 
  nitric 
  acid 
  which 
  they 
  have 
  produced, 
  it 
  will 
  be 
  conveyed, 
  either 
  free 
  or 
  

   combined, 
  to 
  immense 
  distances 
  from 
  the 
  spot 
  where 
  it 
  was 
  developed. 
  But 
  upon 
  

  

  * 
  Phil. 
  Trans., 
  1788, 
  p. 
  261. 
  t 
  Electrical 
  Researches, 
  vol. 
  i., 
  pp. 
  90, 
  91. 
  

  

  