356 
On  the  Power  of  Soils  to  absorb  Manure. 
It  becomes  now  necessary  to  describe  tlie  experiments  that 
have  been  made  with  potash  and  its  salts. 
The  first  solutions  that  were  employed  were  made  of  such 
strength  as  to  compare  as  nearly  as  might  be  with  the  solutions 
of  free  ammonia  and  its  muriate.  At  the  time  of  commencing 
the  potash  experiments  I believed  (as  I still  do)  that  the  pro- 
perty of  the  soil  to  unite  with  alkaline  bases  was  of  the 
nature  of  other  chemical  conbinations,  and  that  consequently  the 
different  bases  would  be  absorbed  in  the  relation  of  their  com- 
bining proportions.  Thus  the  quantity  of  a soil  which  would 
absorb  17  parts  of  ammonia  might  be  expected  to  unite  with  47 
parts  of  potash,  with  31  parts  of  soda,  and  20  parts  of  magnesia, 
these  being  the  quantities  which  would  respectively  combine 
with  a given  weight  of  sulphuric  or  muriatic  acid. 
Nitrate  of  potash  was  the  salt  of  this  alkali  employed  in  the 
experiments. 
Pure  crystallized  nitrate  of  potash  was  dissolved  in  distilled 
water,  the  quantities  of  each  being  so  arranged  that  the  pro- 
portion of  potash  should  be,  equivalent  for  equivalent,  as  nearly 
as  possible  the  same  as  in  the  solution  of  muriate  of  ammonia. 
An  analysis  of  the  solution  gave  the  following  result : — 
Double  Chloride 
Grains.  of  Platinum  Potash.  Per  Cent, 
and  Potassium. 
278-02  gave  11*89  = 2-2951  or  *8255 
To  correspond  with  the  muriate  of  ammonia  this  solution 
should  contain  • S4G0  per  cent,  of  potash  ; the  resemblance,  how- 
ever, appeared  sufficiently  close  for  the  purposes  of  the  experi- 
ment, and  the  solution  was  consequently  employed. 
The  following  is  an  experiment  with  the  solution  of  nitrate  of 
potash  and  the  white  pottery  clay. 
Experiment  81  : — 
Standard  solution  of  nitrate  of  potash  4000  grains!  Digested  together  at  the  ordinary 
White  clay  . 2000  ,,  / temperature  for  several  hours. 
The  resulting  solution  was  treated  successively  by  hydrate  of  barytes 
and  carbonate  of  ammonia  in  the  usual  way,  to  remove  lime  and  any 
substances  besides  potash,  which  might  have  been  dissolved. 
1st  Determination  of  Potash  in  the  resulting  Liquid — 
Grains.  Platinum  Salt.  Potash.  Per  Cent. 
289-67  gave  9-22  = 1*779  or  -6144 
2nd  Determination — 
254-46  gave  7-91  = 1-5268  or  -6000 
1st  Experiment  . . . -6144  per  Cent. 
2nd  ,,  ...  -6000  ,, 
Mean  . 6072  , , 
100  grains  of  the  original  Solution  contained  -8255  grains  of  Potash. 
100  grains  of  the  resulting  Solution  contained  *6072  ,,  ,, 
Loss  by  each  100  grains  of  Solution  . -2183  ,,  ,, 
