July  i,  1895.J 
THE  TROPICAL  AGRICULTURIST. 
5 
Plaiiltf.—F&hn  oil  is  one  of  the  principal 
articles  of  trade  at  ’.nost  p'aces,  but  in  the  Dibiyauga, 
Miinimba,  and  Ituka  district  very  few  oil  palms  are 
seen.  The  forest  is  very  dense  in  these  parts,  which 
will  account  for  their  scarcity.  From  Ndebiji  to 
the  Akwa  lliver  they  are  fairly  plentiful,  in  fact, 
some  nuts  seen  near  Okorora  were  tlie  finest  I have 
ever  come  across. 
A tree,  which  is  called  by  the  natives  Inoi,” 
which  is  also  fairly  common,  yields  from  its  Feeds 
a very  line  limpid  oil  that  they  use  for  anointing 
themselves  and  . for  food.  It  is  doubtful  if  there  is 
sufficient  quantHy  to  be  worth  ollectiug. 
ARGON,  NITROGEN,  AND  PLANTS. 
The  announcement  that  Lord  R.iyleigh  and  Pro" 
fessor  Ramsay  have  succeedeed  in  proving  that  there 
exists  in  the  atmosphere  a gas  which  had  hitherto 
been  unsuspected,  is  of  great  intere  t,  not  only  >o 
chemists  and  physicists,  out  also  to  botanists.  Very 
soon  after  the  discovery  of  argon,  the  question  was 
raised,  “ Do  plants  assimilate  argon  ? ’ and  Professor 
Ramsay  elaborated  a series  of  experiments,  to  find 
out  if  he  coul  1 throw  some  liilit  on  a subject 
which  is  naturally  interesting  to  botanical  workers. 
The  first  thing,  of  course,  was  to  find  out  w'hether 
there  was  any  argon  in  a nitrogenous  vegetable,  so 
Vrofc.ssor  Ramsay  set  to  work  to  see  if  ho  could 
discover  argon  in  nitrogenous  vegetables  and  animal 
tissues,  i’cas  and  dead  mice  were  desiccated,  and 
then  treated  by  Dumas'  imbdiod  for  extracting  nitro- 
gen. 'Ibis  consists  of  mi\ingtlic  powdered  mice  or 
Peas  with  copper  oxide  and  lead  chromate  in  a 
heated  tube,  whereby  a'l  the  hydrogen,  oxygen, 
carbon,  sulphur,  Ac.,  are  removed,  and  the  nitrogen 
is  collected.  This,  of  course,  w'as  acting  on  the 
assumption  that  the  process  which  liberates  nitrogen 
also  liberates  argon,  and  this  is  by  no  means  certain  ; 
in  fact,  Professor  Rainsy,  by  Dumas’  method,  faihd — 
so  it  is  understood— to  discover  argon  either  in  Peas 
or  in  mice. 
It  may  be.  of  course,  that  the  method  employed 
is  at  fault,  and  that  some  new  arrangement  will  have 
to  be  employed  to  induce  this  very  inert  gaseous 
constituent  of  the  atmosphere  to  sliow  its  presence, 
or  it  may  be  that  plants  are  quite  unable  to  assimilate 
even  a particle  of  the  argon  which  is  to  be  found 
floating  in  the  atmosphere. 
But  it  is  to  be  hoped  that  farther  experiments  on 
this  subject  will  be  made,  for  the  relation  of  the 
atmosphere  to  plant  life  ia  a very  important  one. 
Since  the  classic  experiments  of  Priescly  and  others 
towards  the  close  of  the  last  century,  m ny  researches 
of  a laborious  character  have  been  made  to  find  out 
the  percentage  in  the  air  of  the  gasses  of  which  our 
atmosphere  is  composed.  We  do  not  know  yet 
whether  argon  is  an  clement,  or  a mixture  of 
elements.  If  it  is  a single  element,  iis  atomic 
weight  must  he  about  lU,  and  in  that  case  no  place 
13  ready  for  it  in  Mendeli  eft's  table  of  the  e.leoieuts. 
The  simplest  way  out  of  the  difficulty  would  be  to 
suppose  that  argon  is  a mixture,  but  there  is  con- 
flicting evidence  as  to  this.  Mr.  Crookes,  with  his 
spectroscope,  says  one  thing;  M.  Olszewski,  with 
his  low-temperature  thermometer,  says  another. 
Plants,  wc  know,  do  not  possess  the  p wer  of 
absorbing,  or,  at  least,  of  assimilating,  the  free 
oxygen  and  hydrogen  gasses;  in  all  probability,  argon 
does  not  enter  into  their  composition.  But  ixpeii- 
meuts  might  be  made  in  growing  suitable  plants  in 
an  atmosphere  of  pure  argon  or  argon  mixed  with 
pure  oxygen,  on  a bed  of  pure  sand.  It  will  be 
remembered  that  it  was  with  such  experiments  that 
Hellriegel  and  W’^ilfaith  in  Germany  conclusively 
proved  that  free  nitrogen  was  fixed  by  leguminous 
plants  in  symbiosis  with  microbes,  as  well  as  by 
mixtures  of  the  lower  organisms  inhabiting  soils, 
green  algas,  and  microbes. 
The  chemical  history  of  the  atmosphere,  from  its 
origin  to  the  present  day,  has  attracted  the  attention 
of  many  observers.  Koene  and  Stas  in  Brussels, 
and  Dr.  T.  1j.  Phipsoa  in  England,  have  all  brought 
forward  theories.  Briefly  stated,  they  amount  to 
this.  The  primitive  atmosphere  was  composed  of 
nitrogen,  the  substance  which  has  the  least  tendency 
to  combine  directly  with  others.  Into  this  atmo- 
sphere Volcanic  action  evolved  large  quantities  of 
carbonic  acid  and  water.  There  was  no  free  oxygen 
in  this  primitive  atmosphere,  but  it  was  in  this 
primitive  atmosphere  of  nitrogen,  with  more  or  less 
carb  mic  acid  and  vapour,  that  the  first  orgacised 
beings  (i.e.,  ])lants)  made  their  appearance ; experi- 
ments have  shown  that  many  plants  of  our  own  day 
ca  1 vegetate  in  an  atmosphere  of  this  kind,  in  which 
animal  life  is  quite  impossible.  In  fact,  according 
to  these  physicists,  all  the  oxygen  mw  existing  in 
the  earth’s  atm  sphere  is  due  to  vegetation  extending 
over  immense  periods  of  time.  It  is  generally  allowed 
that  the  function  of  nitrogen  in  the  atmosphere  is 
to  dilute  the  oxygen,  which  would  otherwise  be  too 
strong  for  human  beings.  How  argon  will  com- 
bine with  all  these  theories  remains  to  be  seen. 
— H.  C.  P. — Gardeners'  Chronielc. 
THE  TREATMENT  OE  THE  SOIL  IN  LIME 
PLANTATIONS. 
(7L/  /•’.  Watts,  F.  /.  (J.,  Assoc.  J/aso/t. 
Oulli''ir,  Guvt,  Chemist^  Antujua.) 
The  (|uostion  <if  the  application  of  manures  to  fruit 
trees  is  one  which  is  sure  to  require  consideration 
sooner  or  later  in  all  districts  wmcrc  large  orchards 
are  established  ; and  as  little  has  been  written  on 
the  subject  hr  relation  to  Lime  trees  the  following 
notes  may  prove  acceptable  to  those  interested  in 
the  Lime  industry. 
Ill  coii-idering  the  question  of  manuring  this  or 
any  other  crop,  it  is  of  essential  importance  that 
the  mechanical  condbiuu  or  heart  of  the  soil  should 
first  of  all  receive  attention.  Unfortunately  this 
condition  or  heart  includes  a numbpr  of  physical 
factors  which  do  not  readily  admit  of  representation 
by  figures,  such  as  friability,  porosity,  aeration, 
water  holding  power  nnd  many  others,  though  these 
points  are  readily  recognised  by  the  practised  eye 
and  hand.  It  is  to  the  maintenance  of  this  condition 
or  heart  that  the  principal  operations  of  tillage  arc 
directed.  The  roots  of  a Lime  tree  like  all  others 
must  he  supplied  with  air  as  well  as  moisture ; they 
will  not  penetrate  badly-drained  soils  to  any  consider- 
able depth,  and  und' r these  condiliors  suffer  from 
shallowness  of  the  available  soil,  the  impervious 
subsoil  being  of  little  more  use  to  the  tree  than 
impenetrable  rock.  From  the  character  of  the  Lime 
crop  and  its  cultivation  there  is  a decided  tendency 
for  the  soil  of  Lime  orchards  to  fall  off  in  condition, 
particularly  where  the  soil  is  of  a clayey  character, 
and  this  danger  is  increased  when  the  orchard  is 
made  to  serve  also  as  a pasture  for  stock;  the 
trampling  of  the  animals,  especially  i'l  wet  weather, 
hardens  the  sol',  reduces  its  porosity  and  prevents 
the  free  spreading  of  the  roots  of  the  Lime  trees. 
The  necessary  aeration  of  this  soil,  could  be 
readily  secured  by  growing  some  intermediate  crop 
between  the  Lime  trees,  either  with  the  idea  of 
making  this  intermediate  crop  remunerative  in  itself, 
or  of  turning  in  the  resulting  growth  as  a green 
dressing.  In  the  first  case  careful  attention  must 
be  paid  to  the  manuring  in  order  that  the  removal 
of  double  crops  may  not  unduly  impoverish  the  soil ; 
but  if  reasonable  care  be  taken  various  crops  may 
be  raised  and  the  soil  left  in  an  improved  condition 
at  the  end  of  a given  period ; such  crops  as  corn, 
potatoes,  yams,  and  arrowroot  lend  themselves  to 
this  form  of  cultivation  and  might  be  grown  with 
advantage  in  newly-planted  Lime  orchards,  for  the 
apace  of  several  years.  Situated  as  some  Lime 
orchards  are,  it  is  sometimes  difficult  to  find  a 
market  for  the  produce  grown  in  this  manner  In 
such  cases  the  cultivation  of  intermediate  crops  for 
green  dressings  commends  itself,  and  for  this  purpose 
nothing  surpasses  the  pigeon  pea  in  ultilitj'.  It  is 
novv  well  known  that  plants  of  the  Bean  or  Pea 
tribe  possess  the  remarkable  power  of  assimilating 
the  nitrogen  of  the  atmosphere — a power  which  other 
plants  do  not  possess.  In  conseq  lence  of  this  beans 
and  peas  are  able  to  thrive  in  soils  so  poor  in 
nitrogen  that  other  plants  could  grow  iu  them  with 
