320 
On  the  Power  of  Soils  to  absorb  Manure. 
Analysis  of  White  Clay. 
When  dried  at  212°,  it  contained,  in  100  parts — 
. 42-28 
. 11*45 
. 3-53 
. 0-55 
. 0-22 
. 6-15 
. 18-73 
. 12-15 
. 2-11 
. 0-27 
. 0-29 
. 0-86 
. 1-41 
100-00 
It  will  be  observed  that  a boiling  mineral  acid  is  unable  to  dis- 
solve out  all  the  lime  from  the  clay ; and  it  is  this  remaining  lime 
which  enables  the  clay,  as  will  presently  be  seen,  after  treatment 
with  acid,  to  absorb  ammonia  in  very  slightly  diminished  extent. 
We  now  proceed  to  describe  experiments  on  the  filtration  of 
different  solutions  through  soils. 
On  the  Absolution  of  Ammonia. 
Experiment  No.  1. — The  tube  employed  in  this  experiment  was  20  inches 
long  and  £ inch  in  internal  diameter.  When  about  two-thirds  filled  with 
soil  it  contained  2800  grains  of  the  latter.  The  soil  used  was  Mr.  Pusey's 
red  soil  in  coarse  powder,  dried  in  the  air.  The  solution  of  ammonia 
employed  was  made  by  diluting  1 ounce  of  the  strongest  ammonia  with 
11  ounces  of  water,  ft  contained  therefore  about  1-5  percent,  of  real 
ammonia,  and  was  of  course  highly  pungent  to  the  smell.  The  solution 
took  from  li  to  2 hours  to  run  through.  The  first  portions  were  found  to 
be  entirely  free  from  the  pungent  smell  of  ammonia.  When  1 ounce  of 
liquid  had  percolated,  it  was  examined  by  the  usual  tests  for  free  ammonia, 
and  by  the  help  of  solution  of  potash  for  salts  of  ammonia,  but  no  trace 
of  the  alkali  in  any  form  was  detected  in  it.  The  experiment  was  discon- 
tinued at  this  point.  On  pushing  out  the  wet  soil  from  the  tube,  the 
lower  portions  being  the  first  ejected,  the  smell  of  ammonia  became 
powerful  at  once,  as  if  the  presence  of  an  atmosphere  of  common  air  as- 
sisted its  volatilization,  although  the  liquid  was  unable  to  bring  it  away, 
but  subsequent  experiments  proved  beyond  a doubt  that  this  circumstance 
was  merely  accidental,  and  that  had  the  operation  been  continued  the 
ammonia  would  shortly  have  passed  through,  the  soil  being  saturated 
with  it. 
Experiment  2. — The  same  soil  powdered  and  made  to  pass  through  a 
sieve  of  80  holes  to  the  inch.  The  tube  was  much  shorter  than  in  the 
previous  experiment,  and  the  column  of  soil  about  1 foot  in  depth,  weigh- 
ing about  1500  grains.  The  solution  of  ammonia  was,  on  the  other  hand, 
much  stronger  than  in  Experiment  No.  1 ; it  consisted  of  equal  parts  of 
strongest  ammonia  and  water.  Only  so  much  liquid  was  used  as  to  sink 
through  the  soil  without  dropping  from  it.  The  solution  and  soil  were 
{Silica  . 
Alumina  . 
Oxide  of  iron 
Lime  . 
Magnesia  . 
'Water  of  combination 
Soluble  in  acids, 
41-97 
Silica  . 
Alumina  . 
Oxide  of  iron 
Lime  . 
Magnesia  . 
Potash  . 
Soda  . . 
