26  Some  Secondary  Actions  of  Manures  upon  the  Soil. 
of  soda,  whereupon  a quantity  of  soil  from  the  nitrate 
plot  on  the  grass  land  was  washed  with  hot  water 
to  see  how  much  alkali  could  be  extracted  from  it,  this 
particular  plot  being  selected  because  the  soil  contained  no 
carbonate  of  lime,  which  itself  might  give  rise  to  a soluble 
alkali.  Table  IV.  shows  the  quantities  of  carbonate  of  soda 
that  were  found  in  the  successive  9-inch  layers  down  to  a depth 
of  3 feet,  the  results  being  calculated  as  lb.  of  carbonate  of 
soda  per  acre. 
Table  IV. — Carbonate  of  Soda  (lb.  per  acre)  in  soil  of  Plot  14, 
Park  Grass  Field,  Rothamsted. 
1st  depth  2nd  depth  3rd  depth  4th  depth 
0—9  in.  9—18  in.  18—27  in.  27—36  in. 
66  37  33  39 
It  will  be  seen  that  the  total  amounts  to  no  less  than  175  lb. 
of  carbonate  of  soda,  which  is  the  chemical  equivalent  of  280  lb. 
of  nitrate  of  soda,  or  about  one  half  of  the  yearly  application 
(550  lb.  per  acre)  of  nitrate  of  soda  to  this  plot.  We  cannot  base 
our  calculations  on  more  than  the  year’s  application,  because 
neither  nitrate  nor  carbonate  of  soda  are  in  the  least  retained 
by  the  soil  and  both  must  wash  out  pretty  completely  during 
a wet  winter.  The  problem  then  was  thus  far  cleared — it  had 
been  shown  that  the  soils  which  receive  nitrate  of  soda  after- 
wards contain  carbonate  of  soda  equivalent  to  as  much  as 
one  half  of  the  nitrate  applied,  and  this  carbonate  of  soda  was 
in  itself  enough  to  account  for  the  bad  texture  of  the  soils,  a 
bad  texture  which  is  due  not  to  any  special  defect  of  com- 
position but  to  the  deflocculation  of  the  clay  particles  in  the 
soil.  The  next  question  was  to  account  for  the  formation  of 
the  carbonate  of  soda,  and  here  certain  well  established  facts 
suggested  an  explanation ; facts  to  which  the  late  Mr.  Waring- 
ton  had  drawn  particular  attention  in  a paper  contributed  to 
the  Journal  of  the  Royal  Agricultural  College  at  Cirencester 
in  1899.  Warington  had  pointed  out  that  when  the  com- 
position of  any  plant  is  examined  the  acids  and  bases  do  not 
balance  one  another  but  the  acids  are  in  excess,  even  though 
we  leave  out  of  account  the  vegetable  acids  manufactured  by 
the  plant.  It  is  one  of  the  fundamental  conceptions  of 
chemistry  that  in  any  compound,  say  phosphate  of  lime,  there 
will  be  a definite  and  invariable  proportion  between  the  two 
components — the  phosphoric  acid  and  the  lime,  similarly  in 
sulphate  of  lime  the  ratio  of  lime  to  sulphuric  acid  is  fixed. 
Now  taking  the  ash  of  a plant  and  summing  the  acids — 
phosphoric  and  sulphuric  acid,  chlorine,  against  the  bases — 
potash,  soda,  lime,  magnesia,  iron,  there  is  generMly  an 
excess  of  bases,  but  this  excess  is  turned  into  a deficit  as  soon 
as  we  bring  into  account  the  nitrogen  in  the  plant,  which 
