112 
Experiments  of  the  late  }fr.  James  Mason. 
The  low  result  for  the  surface  soil  in  the  lucerue  tank  is 
due  to  the  mixture  referred  to  al)ove. 
At  this  time  of  day  it  is  needless  to  labour  the  point 
brought  out  by  Mr.  Mason’s  experiments — that  the  leguminous 
plants  do  gather  nitrogen  from 'the  atmosphere — but  when  the 
trials  were  started  the  work  of  Hellriegel  and  Wilfarth  was 
still  novel,  and  though  it  served  to  explain  a long  series  of  out- 
standino-  difficulties  about  the  amount  of  nitrogen  found  in  the 
clover  crop,  it  ran  so  counter  to  what  had  l)een  the  accepted 
o[)inion  for  thirty  years  that  experimenters  everywhere  were 
submitting  it  to  careful  verification.  Incidentally  the  tank 
experiments  showed  that  lucerne  was  by  far  the  best  nitrogen 
collector  among  the  plants  tried,  a result  which  began  to  have 
an  increasing  effect  on  Mr.  Mason’s  Held  experiments  and 
fanning  practice,  since  he  found  a difficulty  in  establishing 
good  plants  of  clover  in  the  dry  seasons  then  j)revailing. 
Other  of  these  pot  and  tank  ex|)eriihents  dealt  with  the 
power  of  cereals  and  of  leguminous  plants  to  obtain  the  potash 
and  phosphoric  acid  from  various  natural  sources.  Felspar, 
coarse  and  fine,  and  subsoil  clay,  weathered  or  dried  at  a high 
temperature,  were  tried  as  sources  of  potash,  mixed  with  sand 
and  peat  moss  litter  to  form  an  artificial  soil.  The  ])lants, 
especially  lucerne,  were  found  well  able  to  obtain  .sufficient 
potash  from  such  sources,  even  when  the  percentage  of 
felspar  in  the  soil  was  reduced  to  10  })er  cent,  or  so.  The 
same  subsoil  clay,  phosphate  of  iron,  precipitated  or  calcined, 
and  “ dufrenite,” ' raw  and  calcined,  were  also  tried  as  .sources 
of  phosphoric  acid.  The  residts,  however,  are  not  in  a form 
which  admits  of  exact  tabular  comparison,  but  serve  to  show  that 
plants  have  a very  great  power  of  obtaining  footl  from  insoluble 
mineral  sources  if  they  are  well  sup])lied  with  nitrogen. 
The  net  result  of  the  tank  experiments  was  thus  to  confirm 
for  a large  number  of  leguminous  plants  the  conclusions  of 
Hellriegel  and  Wilfarth  as  to  their  |)ower  of  assimilating  free 
nitrogen,  and  also  to  show  that  lucerne  was  the  most  persistent 
and  vigorous  of  the  nitrogen  collectors.  After  18fi8  the  tanks 
were  practically  given  n\)  further  attention,  as  Mr.  Mason  was 
busy  trying  to  translate  their  lessons  into  practice. 
E.xi’Kriments  on  the  Weatiiehinu  ok  Subsoils. 
Among  the  ideas  with  which  Mr.  Mason  started  his  farming 
experiments  was  that  of  utilising  to  a greater  extent  than  at 
' A double  phosphate  of  Manganese  and  Iron  found  as  a mineral. 
