Leifiuninous  Plants  as  rollertors  of  Nitro<jen. 
1 01) 
niucli  wanting  to  .s(“o  the  ])aj>er  on  nitrogen  tliat  I nnder.staml 
is  to  he  printed  in  tlie  Transactions  of  the  Hoyal  Society.  I 
hope  you  will  turn  out  wrong  in  the  end,  and  that  some  plants 
will  he  found  to  he  absorbers  of  atmospheric  nitrogen.  Con- 
sidering that  the  earth  was  once*  incandescent,  where  did  all 
the  nitrogen  come  from  that  now  exists  in  soils  and  rocks?” 
Mr.  Mason  inaugurated  a similar  scheme  of  experiment  but 
on  a somewhat  larger  scale  at  Eynsham  ; at  the  same  time  he 
began  various  attempts  to  utilise  h'guniinous  crops  more  freely 
on  the  estate.  Of  course  he  tri('d  many  things  which  failed 
or  led  to  no  results  of  consecpience,  but  thi-ee  lines  of  investiga- 
tion may  be  picked  out  which  did  lead  to  practical  results.  In 
the  first  place  the  ‘‘tank”  experiments  showed  which  of  the 
leguminous  plants  were  most  effective  in  gathering  nitrogen  ; 
the  ‘'weathering”  experiments  showed  what  the  subsoil  could 
be  made  to  yield  ; and  the  “ field  ” experiments  were  attempts 
to  turn  to  {)ractical  account  the  two  j)rinciples  thus  elucidated. 
Thk  T.vnk  anj)  Pot  Expkuiments. 
For  the  purpose  of  these  ex[)erinients  twelve  brick  tanks 
were  built,  each  (i  by  3 ft.  by  (5  ft.  deep  ; six  others  were  4 ft. 
scpiare  by  b ft.  deep  ; and  forty  others  were  only  15  in.  s({uar(‘ 
by  3 ft.  deep.  In  addition,  a large  number  of  experiments 
were  made  in  glazed  drain  pij>es  set  on  end.  Arrangements 
w'ere  made  to  collect  the  drainage  from  each  tank,  and  the 
whole  wais  freely  exposed  to  the  weather  in  the  open,  but 
beneath  wire  netting  to  keej)  away  birds.  As  the  purpose 
of  the  experiment  was  to  test  the  nitrogen  collecting  power 
of  the  various  leguminous  plants  and  their  ability  to  prepare 
the  land  for  carrying  nitrogen  consuming  crops  like  the 
cereals,  an  artificial  soil  was  pre])ared  containing  no  combined 
nitrogen.  The  local  clay  subsoil  was  carefully  charred  to 
remove  any  organic  niatt(*r,  passed  thi'ough  a sieve  and  a 
mixture  made  as  follow's; — burnt  clay  100,  carbonate  3 and 
sulphate  of  lime  2 parts,  basic  slag  3 parts,  kainit  2 ]>arts. 
With  this  mixture — containing  no  nitrogen  but  an  abundance 
of  })hosphates,  potash,  lime,  and  all  the  other  mineral  con- 
stituents of  the  plant’s  ash — each  tank  was  filled  early  in 
1890.  In  order  to  inoculate  the  ])lants  with  their  appro- 
priate bacteria  each  seed  w’as  sown  in  a ]>inch  of  garden 
mould  oi>  the  surface  of  the  artificial  soil.  The  produce 
was  cut  and  dried,  the  amount  of  nitrogen  being  calculated 
from  the  dry  weight  obtained. 
