368 
On  the  Power  of  Soils  to  absorb  Manure. 
putrefaction  are  very  much  modified  when  the  soil  comes  into 
play.  An  experiment  of  the  same  nature  as  those  before  men- 
tioned was  made  with  human  foeces,  which  were  covered  in  two 
glasses — the  one  portion  with  sand  and  the  other  with  white  clay, 
each  to  the  depth  of  about  2 inches.  The  materials  were  loosely 
placed  in  the  glasses,  and  not  incorporated  together,  so  that  the 
air  had  access  to  the  excrement,  although  imperfectly.  The  smell 
from  the  glass  containing  sand,  particularly  after  some  little  time, 
was  very  bad,  but  from  the  fceces  and  clay  no  other  than  a slightly 
acid  but  not  putrid  smell  was  for  weeks  evident. 
Having  now  brought  forward  ample  proofs  of  the  existence,  in 
reference  to  the  organic  and  inorganic  substances  of  manure,  of  a 
power  in  soils,  which  has  hitherto  hardly  been  suspected,  I shall 
endeavour  to  give  a practical  idea  of  the  extent  of  the  property 
when  it  acts  upon  the  mixed  constituents  of  a manure,  by  describing 
two  experiments  which  have  been  made  with  that  view.  The  first 
of  these  shows  the  action  of  white  clay  upon  flax-water — the  putrid 
liquid  which  results  from  the  steeping  of  the  flax  plant;  the 
second  experiment  exhibits  the  action  of  a soil  upon  the  water  of 
a London  sewer. 
Experiment  with  Flax-water  and  Clay. — The  following  is  the  analysis 
of  the  flax-water  used  in  this  experiment : — 
An  imperial  gallon  contained — 
Grains. 
Organic  matter 180-80 
Phosphoric  acid  . . . . . 8 ‘70 
Sulphuric  acid  • . . . . 18*08 
Carbonic  acid  . . . . . . 21*53 
Lime  . . . . . • . .33*06 
Magnesia  .......  8*54 
Peroxide  of  iron 17*44 
Potash  . . . .....  48-84 
Soda none 
Chloride  of  sodium  . . . . 42*21 
Chloride  of  potassium  . . . . 60*83 
Silica 4*93 
Total  solid  matter  in  a gallon  445*02 
The  organic  above  contained  3*28  grains  (in  a gallon)  of  nitrogen,  none 
of  which  appeared  to  be  in  the  form  of  ammonia. 
Experiment  96. — With  48  ounces  of  this  flax-water  16  ounces  of  white 
clay  were  mixed  in  a wide-mouth  bottle,  the  materials  being  well  agitated 
together.  The  fetid  smell  of  the  liquid  was  greatly  diminished,  but  not 
entirely  removed.  After  the  addition  of  8 ounces  more  of  the  clay/ the 
offensive  odour  of  the  flax-water  was  entirely  removed,  but  the  liquid  still 
retained  a peculiar  odour,  which  seems  to  be  due  to  some  acid  substance 
formed  in  the  fermentation  of  the  flax. 
The  clay  was  now  allowed  to  fall  to  the  bottom,  and  the  clear  and 
colourless  fluid  was  decanted  off,  and  evaporated  carefully  to  dryness. 
The  residue  still  contained  organic  matter  of  some  sort,  but  it  was  entirely 
free  from  nitrogen.  Neither  did  it  contain  phosphoric  acid,  potash,  or 
magnesia.  The  following  analysis  exhibits  the  composition  of  the  mineral 
residue  of  an  imperial  gallon  of  this  liquid : — 
