On  the  Power  of  Soils  to  absorb  Manure . 
349 
100  grains  of  the  original  Liquid  contained  «...  *3060  grains 
100  grains  of  the  resulting  Liquid  contained  ....  *2055  , , 
Loss  hy  each  100  grains  of  the  liquid  . • • 1005  , , 
The  whole  quantity  of  liquid  (4000  grains)  will  therefore  have  lost 
4*020  grains  of  ammonia,  which  has  been  absorbed  by  2000  grains  of  clay. 
The  absorption  by  the  clay  is  consequently  *2010  per  cent. 
It  will  be  seen  from  the  experiments  just  described  that  the 
absorptive  property  of  the  day  is  not  the  same  under  all  circum- 
stances. Thus,  when  with  the  solution  of  muriate  of  ammonia 
TVth  of  its  weight  of  clay  was  digested,  the  absorption  was  *2847 
per  cent.  When  the  quantity  of  clay  was  increased  to  one  half 
the  weight  of  the  solution,  the  per-centage  absorption  is  reduced 
to  *2010,  or  little  more  than  two-thirds.  The  intermediate 
relation,  or  where  the  clay  is  to  the  solution  as  1 to  4 (being  in 
the  other  instances  as  1 to  10,  and  1 to  2),  gives  only  a slightly 
increased  absorption  over  the  last;  and  it  may  be  assumed  that  a 
further  increase  of  the  proportion  of  the  soil  would  not,  beyond 
this  point,  materially  diminish  the  amount  of  ammonia  which  a 
given  weight  of  the  soil  would  remove  from  solution. 
I am  unable  at  the  present  time  to  offer  a satisfactory  explana- 
tion of  this  circumstance,  and  only  allude  to  it  in  order  to  show 
that  be  the  absorbent  substances  in  the  soil  what  they  may,  it 
would  seem  necessary  to  isolate  them,  and  study  their  properties 
in  a less  complicated  condition,  if  we  wish  to  make  material 
progress  in  the  knowledge  of  those  properties  as  naturally  ex- 
libited  in  the  soils  themselves. 
By  employing  a comparatively  large  quantity  of  soil  in  relation 
to  the  liquid,  we  have  in  the  last  experiments  much  reduced  the 
liability  to  error.  A deviation  from  the  truth  in  the  estimation 
of  the  strength  of  the  liquid,  is  in  this  way  only  doubled  when 
referred  to  the  soil,  instead  of  increased,  as  it  was  before,  ten  or 
twelve  times.  In  the  succeeding  experiments  these  quantities 
are  therefore  uniformly  employed. 
The  next  experiment  shows  the  effect  of  burning  upon  the 
absorptive  powers  of  a clay  : — 
Experiment  73. — Pipe-clay  dried  was  made  to  pass  through  a sieve  of 
40  holes  to  the  inch  ; a quantity  of  it  was  then  placed  in  a covered  Hessian 
crucible  and  strongly  heated  in  the  laboratory  furnace  for  two  hours. 
Owing  to  the  cohesion  of  the  particles  produced  by  the  heat,  it  was 
found  that  this  burnt  clay  would  subside  from  a solution  of  free  ammonia, 
which  was  accordingly  used. 
Burnt  pipe-clay  and  ammonia — 
Standard  solution  of  Ammonia 
Burnt  Clay 
2000  °ra  "'s  | Digested  for  two  hours. 
1st  Distillation  of  the  resulting  Liquid — 
Grains.  Platinum  Salt.  Ammonia.  ‘ Per  Cent. 
229-63  gave  7*74  = -59048  or  -2571 
