112  Improvement  of  Land  by  Warping. 
The  peaty  soil,  on  the  contrary,  did  not  exhibit  either  of  the 
bad  qualities  observed  in  the  case  of  the  sandy  soil ; it  was  not 
only  sufficiently  hygrometric,  but  it  also  possessed  (with  the 
single  exception  of  phosphoric  acid)  every  constituent  necessary 
for  the  nourishment  of  plants.  In  this  instance,  therefore,  nearly 
the  whole  of  the  improvement  that  the  process  in  question  was 
capable  of  effecting  in  the  soil  must  have  depended  upon  its 
mechanical  alteration. 
It  is  not  only  in  the  operation  of  warping  that  great  fertility 
has  been  observed  to  be  possessed  by  the  mud  of  large  rivers. 
Nearly  the  whole  of  Lower  Egypt,  it  is  well  known,  would  be 
completely  sterile  were  it  not  for  the  alluvion  that  is  deposited 
upon  the  soil  during  the  periodic  overflowings  of  the  river  Nile. 
About  the  time  of  the  summer  solstice,  between  the  months  of 
May  and  June,  continued  heavy  rains  occur  within  the  tropics, 
and  these,  being  conducted  into  the  bed  of  the  river,  swell  its 
waters  to  such  an  extent  that  they  overflow  their  boundaries,  and 
inundate  the  lands  on  either  side,  carrying  with  them  the  fine 
mud  and  other  matters  which  they  have  collected  in  their  down- 
ward course  through  the  hilly  countries  in  the  interior.  This 
mud  is  gradually  deposited  upon  the  surface  of  the  arid  sand, 
and,  as  soon  as  the  waters  subside,  forms  a fertile  soil,  which  is 
immediately  sown  down  with  rice  and  other  grain  crops  by  the 
natives,  who  ignorantly  attribute  this  phenomenon  to  a special 
interference  of  a supernatural  power  for  their  benefit. 
There  is  a very  marked  resemblance  to  be  detected  between 
the  composition  of  the  mud  which  is  thus  deposited  by  the  above- 
mentioned  river  and  that  of  the  warp  as  it  is  shown  by  my  own 
experiments.  According  to  M.  Regnault’s  analysis,  which  was 
published  in  the  Memoirs  of  the  Commission  of  Egypt  ( Histoire 
Naturelle , tome  ii.  p.  405),  a specimen  of  the  former,  collected  at 
500  fathoms,  contained  of — 
Water  .... 
. 11 
Organic  matters  . 
9 
Oxide  of  iron  . 
. . . 6 
Silica  .... 
4 
Carbonate  offline 
. 18 
Carbonate  of  magnesia 
. . . 4 
Alumina 
. 48 
100 
A still  more  recent  analysis,  however,  performed  by  M. 
Lassaigne  ( Comptes  Metidus , No.  17,  Avril  22,  1844),  and 
undertaken  at  the  request  of  M.  de  Las  Casas,  has  proved  it, 
after  being  dried  at  212°  Fahr.,  to  consist  of — 
