388 
Ammonia. 
fluid  are  necessary  to  make  that  quantity  act, — a bulk  of  fluid 
scarcely  attainable.  Unless,  therefore,  gypsum  find  the  requi- 
site amount  of  liquid,  which  in  a stable  must  be  very  doubtful, 
its  action  will  be  precarious  ; and  again,  how  can  we  be  cer- 
tain that  when  evaporation  takes  place  the  process  may  not  be 
reversed — be  succeeded  by  the  contrary  action,  as  between  salts 
in  the  state  of  powder,  and  thus  the  ammonia  fixed  in  the  yard  be 
released  again  in  the  dung-hill  ? Green  vitriol  has  been  pro- 
posed, but  Sprengel* * * §  proves  it  to  be  too  expensive.  “ For  23  lbs. 
of  ammonia  so  prepared  require  53  lbs.  of  sulphuric  acid,  and 
100  lbs.  of  green  vitriol  contain  only  29  lbs.  of  sulphuric  acid.’^ 
Now,  green  vitriol  or  copperas  costs  from  5 Z.  to  6k  per  ton.  The 
cost  of  sulphate  of  ammonia  so  made  would  be  about  12Z.  per  ton, 
which  price  brings  out  pure  ammonia  at  about  6 d.  per  lb.  Now, 
when  guano  is  at  10Z.  per  ton,  the  present  price,  the  ammonia  irr 
that  form  costs  only  5cZ.  per  lb.  ;f  so  that  a farmer  using  green 
vitriol  as  a fixer  buys  of  himself  for  six  pence  what  he  could  purchase 
in  the  market  (or  Jive.  Of  the  so-called  “fixers,”  then,  gypsum  is 
uncertain,  vitriol  costly,  alum  doubly  so.  There  remains  sul- 
phuric acid,  but  this  last  may  be  reserved  until  we  come  to  the 
treatment  of  dung. 
The  management  of  ammonia  in  the  yard  is  still  dark  and 
difficult.  Its  management  in  the  field  is  simplified  by  an  im- 
portant discovery  of  Mr.  Thompson’s, \ which  Mr.  Way’s§  experi- 
ments have  greatly  enlarged  and  diversified.  If  you  pour  a solu- 
tion of  ammonia  on  loamy  soil,  the  water  when  it  escapes  below 
will  be  found  free  from  ammonia.  This  action  is  not  at  all  the 
same  with  filtration,  for  if  a portion  of  soil  be  thrown  into  the 
liquid  the  ammonia  equally  disappears  in  a few  minutes.  There 
is,  therefore,  a chemical  action,  and  it  seems  a new  chemical 
action,  reversing,  as  under  the  law  of  Berthollet,  the  ordinary 
conduct  of  chemical  substances  towards  each  other.  The  loam 
thus  arrests,  not  ammonia  only,  but  everything  which  can  serve  as 
manure  for  plants.  Putrid  urine,  sewer-water  passing  through 
loam,  as  Mr.  Huxtable  found,  become  pure  as  well  as  clear. 
Thus,  a deep  loam  is  enabled  to  retain  manure  committed  to  it 
until  the  future  crop  requires  nourishment ; an  important  dis- 
covery, limited  indeed  in  its  application,  as  Mr.  Thompson  can- 
didly shows.  For  the  soil  must  be  deep,  since  dung  is  generally 
ploughed  in  four  inches  deep,  and  twelve  inches  at  least  of  soil 
should  be  under  the  dung  to  secure  “ absorption.”  It  must  be 
a loam,  too,  for  sand  has  not  this  property. 
* On  Animal  Manures,  vol.  i.  p.  470. 
f Way  on  Value  of  Guano.  Journal,  vol.  x.  p.  225. 
$ On  the  Absorbent  Power  of  Soils.  Journal,  vol.  xi.  p.  68. 
§ On  the  Power  of  Soils  to  absorb  Manure.  Journal,  vol.  xi.  p.  313. 
