On  the  Absorbent,  Power  of  Soils. 
71 
after  relating  the  experiments  which  were  next  tried  with  a view 
to  ascertain  whether  this  newly  discovered  absorptive  power  was 
possessed  by  other  varieties  of  soil. 
No.  3. 
The  soil  next  operated  on  was  a specimen  of  black  soil  (from 
the  bottom  of  an  old  stick  heap),  consisting  chiefly  of  decayed 
vegetable  matter;  10  grs.  of  sulph.  and  sesquicarbon.  ammdn. 
were  used  as  before,  in  A and  B respectively,  and  the  process 
above  described  repeated  with  the  following  results  : — 
Grains. 
!5-8  sulphate  of  lime. 
•3  silica. 
A trace  of  sulphate  of  ammonia. 
(•8  sulphate  of  lime. 
■2  silica. 
3'8  salts  of  ammonia. 
This  instance  is  chiefly  remarkable  for  the  large  quantity  of 
soluble  silica,  and  for  the  very  perfect  retention  of  ammonia, 
where  the  sulphate  was  used,  and  the  considerable  quantity  which 
washed  through  when  applied  as  sesquicarbonate.  The  abun- 
dance of  decayed  vegetable  matter  will  account  for  the  silica ; the 
other  fact  is  more  difficult  to  explain. 
No.  4. 
A strong  clay  soil.  The  apparent  influence  of  lime  in  aiding 
the  decomposition  of  the  salts  of  ammonia  was  borne  in  mind 
when  selecting  a specimen  of  strong  clay : and  the  one  here  ex- 
perimented on  had  been  in  grass  for  a great  length  of  time  and 
not  limed  within  the  memory  of  man. 
The  difficulty  of  getting  any  quantity  of  liquid  to  filter  through 
a really  strong  clay  is  such,  that  though  eight  ounces  of  water 
were  poured  into  the  percolators,  nearly  three  weeks  elapsed 
before  three  ounces  had  passed  through,  and  this  quantity  was 
therefore  experimented  on. 
The  result  was  as  follows  : — 
Grains. 
( 1*  sulphate  of  lime. 
A \ '5  organic  matter. 
( Trace  of  ammonia. 
g r • 5 organic  matter. 
' * * ‘ * \ Trace  of  ammonia. 
The  very  small  quantity  of  mineral  substances  obtained  from 
the  water  filtered  through  clay  was  so  remarkable  as  in  the  first 
instance  to  cause  the  result  to  be  unrecorded,  on  the  supposition 
