346 
On  the  Power  of  Soils  to  absorb  Manure. 
lime,  forming  a corresponding  salt  of  that  base,  which  is  not 
retained  by  the  soil. 
The  next  experiment  was  designed  to  determine  the  absorptive 
power  of  a natural  clay  ; the  white  pottery  clay,  before  described, 
being  employed.  It  may  be  worthy  of  notice  that  attempts 
which  were  made  to  find  the  power  which  this  clay  possesses  for 
the  solution  of  free  ammonia  entirely  failed,  from  the  impossi- 
bility of  separating  either  by  subsidence  or  filtration  the  finely 
divided  clay  from  the  solution  ; the  liquid  remained  turbid,  and 
could  not  be  obtained  by  any  process  sufficiently  clear  for  a satis- 
factory experiment.  On  the  other  hand,  the  clay  was  found  to 
subside  quickly  and  perfectly  from  the  solution  of  the  muriate ; 
the  apparatus  which  was  used  in  the  first  trials  with  ammonia 
was  less  necessary  in  operating  with  the  fixed  salts  of  this  base  ; 
but  as  it  prevented  any  evaporation  during  the  process,  its  use  was 
retained  : — 
Experiment  69. — Pipe-clay  and  muriate  of  ammonia.  Pipe-clay  (plastic 
clay)  dried  at  between  150°  and  200°,  and  passed  through  a sieve  of  40 
holes  to  the  inch. 
Solmion  of  Muriate  4000  grains  j Digested  fof  twQ  hours. 
1st  Distillation  of  the  resulting  Liquid — 
Grains. 
151*57 
Platinum  Salt. 
gave  5*39  = 
Ammonia. 
•41093  or 
Per  Cent. 
•2711 
2nd  Distillation — 
215*27 
gave 
7*83  = 
• 59696  or 
*2773 
3rd  Distillation — 
196*39 
gave 
7*32 
•5580  or 
•2842 
1st  Estimation 
2nd  , , 
3rd  ,, 
• • • • 
• • • • 
• 271 1 per  Cent. 
•2773  ,, 
•2842  ,, 
Mean  of  the  3 Experiments  *27753  , , 
100  grains  of  the  original  Solution  contained  *3000  grains  of  Ammonia. 
100  grains  of  the  resulting  Solution  contained  *27753  , , , , 
Loss  by  100  grains  of  Solution  • . . *02847 
The  whole  quantity  of  solution  (4000  grains)  will  therefore  have  lost 
1 *1388  grains  of  ammonia,  which  is  absorbed  by  400  grains  of  soil,  mak- 
ing the  absorption  by  100  grains  of  soil  * 2847. 
It  will  be  seen  by  experiments  before  given  and  by  others  that 
follow  (63,  64,  65,  70,  71,  and  72),  that  the  rate  of  absorption 
was,  in  some  way,  evidently  regulated  by  the  strength  of  the 
solutions,  and  the  relative  quantities  of  these  latter  and  of  the  soils 
employed.  This  fact  must  be  borne  in  mind  in  judging  of  the 
absorptive  power  of  the  clay,  according  to  the  last  experiment ; 
and  although  it  is  certain  that  the  power  of  this  natural  clay 
to  absorb  ammonia  is  less  than  that  of  some  cultivated  soils 
