63 
On  the  Absorbent  Power  of  Soils. 
III. — On  the  Absorbent  Poiver  of  Soils.  By  H.  S.  Thompson. 
To  Mr.  Pusey. 
My  dear  Sir, — Professor  Way’s  lecture  on  the  power  possessed 
by  the  soil  of  absorbing  the  salts  of  ammonia,  potash,  and  other 
substances,  has  naturally  excited  a good  deal  of  attention,  and  I 
have  great  pleasure  in  sending,  as  you  suggest,  an  account  of  my 
experiments  on  this  subject  for  publication  in  the  next  number  of 
the  Journal.  They  were  made  in  the  summer  of  1845,  and  it 
was  my  intention  to  have  published  them  long  ago ; but  1 was 
unwilling  to  send  them  before  the  public  in  an  incomplete  state, 
and  I have  never  found  leisure  to  complete  the  series  I had  chalked 
out.  About  two  years  ago  I communicated  a very  brief  outline 
of  the  results  obtained  to  Professor  Way  and  Mr.  Huxtable,  and 
the  former  gentleman  has,  I understand,  followed  up  the  subject 
and  obtained  numerous  additional  facts  of  great  importance  to 
agriculture. 
The  experiments  were  undertaken  in  consequence  of  the  very 
general  endeavour  that  was  then  being  made  to  prevent  the  escape 
of  ammonia  from  tanks  and  manure  heaps  by  the  use  of  sulphuric 
acid,  either  alone  or  in  combination,  as  sulphate  of  lime,  sulphate 
of  iron,  &c.  Large  quantities  of  sulphate  of  ammonia  were  thus 
formed,  and  as  I was  aware  that  the  soil  had  a certain  power  of 
retaining  ammonia,  I was  anxious  to  test  the  extent  of  this  power, 
and  to  ascertain  whether  it  also  extended  to  the  sulphate,  as  if  not, 
the  use  of  sulphuric  acid  as  a fixer,  though  preventing  the  escape 
of  ammonia  in  a volatile  form,  would  have  been  objectionable 
from  its  forming  a highly  soluble  salt,  that  would  be  readily 
washed  down  into  the  subsoil  or  carried  off  in  drains. 
I had  also  another  object  in  view.  Having  observed  the  great 
waste  of  volatile  and  soluble  fertilizers  which  occurred  in  ordinary 
farm  practice  by  carting  manure  into  large  heaps  some  months 
before  applying  it  to  the  land,  I was  desirous  of  ascertaining 
whether  it  would  be  safe  to  plough  manure  in  at  any  time  during 
the  winter  when  it  was  taken  out  of  the  yard. 
In  conducting  this  inquiry,  I was  fortunate  enough  to  obtain 
the  assistance  of  Mr.  Joseph  Spence,  of  York,  by  whom  the  ex- 
periments were  worked  out,  and  his  high  chemical  attainments 
enable  me  to  speak  with  a degree  of  confidence  of  the  results 
obtained,  which  I could  not  have  done  had  they  been  entirely 
my  own. 
My  first  object  was  to  place  the  soil  to  be  operated  on  in  cir- 
cumstances which  should  approximate  as  nearly  as  possible  to  its 
state  in  the  field.  Glass  percolators  2J  inches  in  diameter  were 
selected,  and  a portion  of  the  cultivated  soil  of  one  of  my  fields  (a 
light  sandy  loam  of  good  quality,  lying  on  the  new  red  sandstone 
