On  the  Power  of  Soils  to  absorb  Manure. 
331 
experiment  with  Mr.  Pusey’s  soil,  the  amount  of  absorption 
seemed  greatly  to  exceed  that  of  Mr.  Huxtable.  At  this  time 
the  impression  left  by  the  experiments  was  that  the  lime  was 
derived  from  carbonate  of  lime,  which,  with  the  different  salts  of 
ammonia,  would  give  carbonate  of  ammonia,  and  a salt  of  lime 
corresponding  with  the  acid  of  the  salt  employed.  This  view 
presumed  that  the  carbonate  of  ammonia  was  the  compound 
really  absorbed  by  the  soil  ; it  appeared,  therefore,  to  be  quite 
possible  that  the  superiority  of  the  one  soil  over  the  other  for  the 
absorption  of  ammonia  from  the  nitrate,  might  be  due  to  the 
presence  of  a larger  quantity  of  carbonate  of  lime ; and  the  fol- 
lowing experiment  was  made  with  the  view  of  testing  the  accuracy 
of  this  opinion  : — 
Experiment  42. — Mr.  Huxtable’s  soil  mixed  with  half  its  weight  of  sand 
and  an  equal  quantity  of  powdered  chalk  ; solution  of  nitrate  of  ammonia 
was  passed  through  it,  as  in  the  other  cases  ; but  so  far  as  might  be  judged, 
the  addition  of  the  chalk  did  not  alter  the  absorptive  power. 
Muriate  of  Ammonia. — Several  experiments  in  the  filtration 
of  a solution  of  sal-ammoniac  through  different  soils  were  made, 
with  results  in  all  respects  similar  to  those  which  other  salts  of 
this  base  afforded,  the  ammonia  being  detained,  whilst  the  chlorine 
was  found  in  the  liquid  in  combination  with  the  base  of  liine. 
As,  however,  some  quantitative  experiments  to  be  presently  de- 
scribed will  give  all  the  information  necessary  with  regard  to  the 
action  of  soils  upon  this  salt,  it  will  be  unnecessary  in  this  place 
to  enter  into  further  details. 
The  instances  that  have  been  adduced  fully  substantiate  the 
law  to  which  there  would  appear  to  be  no  exception,  that  soils 
possess  the  power  of  arresting  and  combining  with  ammonia  and 
perhaps  its  carbonate,  and  through  the  agency  of  lime  with  the 
ammonia  of  the  sulphate,  nitrate,  muriate,  and  other  salts  of  this 
base.  That  sulphate  of  ammonia  should  be  so  acted  upon  seems 
the  more  extraordinary,  inasmuch  as  the  formation  of  this  very 
salt  has  been  looked  upon  as  the  way  in  which  ammonia  and  its 
carbonate  would  become  more  fixed  in  the  soil  and  less  exposed 
to  loss  by  evaporation  when  applied  in  manure. 
Sulphate  of  lime  (gypsum)  has  been  greatly  recommended 
and  extensively  employed  to  fix,  as  it  is  called,  the  ammonia  of 
decaying  animal  or  vegetable  matter,  and  in  the  preparation  of 
manure  it  is  undoubtedly  highly  useful  for  that  purpose.  The 
way  in  which  it  acts  is  simply  this: — Carbonate  of  ammonia, 
the  common  product  of  the  decay  of  all  nitrogenized  matter,  and 
the  form  in  which  ammonia  exists  in  the  air,  is  very  volatile. 
Sulphate  of  ammonia  is  a much  less  volatile  salt,  and  requires, 
indeed,  heat  for  its  dissipation  in  any  quantity.  When  sulphate 
of  lime  is  brought  in  contact  with  carbonate  of  ammonia,  mutual 
