14  Some  Secondary  Actions  of  Manures  upon  the  Soil. 
However,  these  facts  had  been  unknown  until  Way’s  paper, 
and  manure  makers  had  even  been  to  some  trouble  to  render 
insoluble  the  fertilisers  they  were  selling,  lest  losses  by  drainage 
should  ensue.  For  example  Liebig,  as  an  outcome  of  his  theory 
that  the  proper  manure  for  any  crop  is  a mixture  of  the  mineral 
and  ash  constituents  contained  in  that  crop,  had  made  up 
prescriptions  and  given  his  countenance  to  the  sale  of  a set 
of  Liebig’s  manures,  fertilisers  in  which  the  constituents — 
phosphates  and  sulphates  of  soda,  potash,  lime  and  magnesia — 
were  actually  fused  up  with  silica  into  a sort  of  glass  in  order 
to  render  them  insoluble,  the  fused  mass  being  afterwards 
ground  to  a powder  for  distribution. 
Now  Liebig’s  manures  had  proved-  failures  in  practice, 
really  because  of  their  lack  of  nitrogen — that  most  important 
of  manure  constitutents  which  Liebig  persisted  in  regarding 
as  supplied  in  sufficient  quantities  for  the  needs  of  the  plant 
by  the  rain  or  the  atmosphere — but  on  reading  Way’s  paper 
Liebig  thought  that  the  cause  of  their  failure  must  have  been 
the  very  insolubility  he  had  made  such  eflEorts  to  attain.  A 
letter  of  Liebig’s  exists  in  which  he  tells  Way  that  his  paper 
has  cleared  up  for  him  the  cause  of  one  of  the  greatest 
'disappointments  he  had  experienced— the  failure  of  his 
manures  in  practice  ; the  best  work  of  his  life  had  been  given 
to  the  chemistry  of  agriculture,  and  he  had  missed  the  proper 
recognition  of  his  labours  because  of  his  ignorance  of  this  one 
fact  which  Way  had  at  last  brought  to  light. 
In  Way’s  paper  he  fixed  upon  the  double  silicates  in  the  soil 
— the  so-called  zeolites — as  the  agencies  causing  the  absorption 
of  both  ammonia  and  potash  salts,  though  he  also  showed  that 
humus  must  have  an  effect  in  the  same  direction,  because 
of  the  great  absorptive  powers  of  all  soils  rich  in  humus.  As 
regards  the  zeolites  the  action  is  intelligible  enough  ; these 
bodies  are  complicated  double  silicates  of  alumina  and  various 
bases  of  which  lime  is  the  chief  ; in  contact  with  a weak 
solution  of  a salt  of  ammonia,  the  lime  and  ammonia  change 
place,  an  insoluble  zeolite  containing  ammonia  being  formed 
on  one  side,  and  on  the  other  a lime  salt  which  goes  into 
solution.  Way  himself  in  a later  paper  concluded  that  carbonate 
of  lime  in  the  soil  did  not  intervene  in  the  process  ; but  in 
later  years,  as  it  appeared  that  sulphate  of  ammonia  reduced 
the  stock  of  carbonate  of  lime  in  the  soil,  it  began  to  be 
thought  that  there  must  be  a direct  interaction  between 
sulphate  of  ammonia  and  the  carbonate  of  lime  instead  of  the 
zeolites,  as  sonn  as  the  former  was  applied  to  the  soil. 
That  the  use  of  ammonium  salts  as  manure  does  directly 
cause  the  removal  of  carbonate  of  lime  from  the  soil  may  be 
learnt  from  a detailed  examination  of  the  amounts  present  in 
