On  the  Power  of  Soils  to  absorb  Manure . 
359 
1st  Analysis  of  the  resulting  Liquid — 
Grains. 
Platinum  Salt.  Potash. 
Per  Cent. 
119*30  gave 
2*91  = *5617  or 
•4708 
2nd  Analysis — 
190*66  gave 
4*78  = *9226  or 
•4839 
1st  Analy 
sis  ...  *4708  perCent, 
2nd  , , 
. . . *4839  ,, 
• Mean  . . . *4773  , , 
100  grains  of  the  original  Liquid  contained  1*0023  grains  of  Potash. 
100  grains  of  the  resulting  Liquid  contained  *4773  , , ,, 
Loss  by  each  100  grains  of  Solution  . . *5250  ,,  ,, 
The  whole  quantity  of  liquid  (4000  grains)  will  therefore  have  lost 
21  • 00  grains,  which  has  been  absorbed  by  2000  grains  of  clay,  making 
the  absorption  by  100  grains  of  clay  to  be  1*050  grains. 
With  caustic  potash  we  have  then  an  absorption  by  the  clay  of 
double  the  amount  that  occurs  with  the  nitrate  of  this  base. 
Without  stopping  to  account  for  this  circumstance,  for  which 
indeed  the  data  are  insufficient,  we  pass  on  to  other  experiments 
of  a similar  kind. 
Experiment  84. — White  clay  boiled  with  solution  of  . Caustic  Potash  of 
1 per  cent. 
Solution  of  Caustic  Potash  . 4000  grains. 
White  Clay 2000  , , 
boiled  together  for  half  an  hour,  cooled  by  immersion  of  the  flask  in  water, 
and  the  exact  weight  of  the  original  liquid  made  up  by  the  distilled  water, 
so  as  to  compensate  for  loss  by  evaporation. 
1st  Analysis  of  the  resulting  Liquid — 
Grains.  Platinum  Salt.*  ’ Potash.  PerCent. 
214*25  gave  4-62  •=  • -8918  or  -41G2 
2nd  Analysis — 
265*72  gave  5*74  = 1*1079  or  *4169 
1st  Analysis  . . . . • 4162  per  Cent. 
2nd  ,,  ....  *4169  ,, 
Mean  . . . *4165  ,, 
100  grains  of  the  original  Solution  contained  1 *0023  grains  of  Potash. 
100  grains  of  the  resulting  Solution  contained  *4165  ,,  ,, 
Loss  by  each  100  grains  of  Solution.  . *5858  ,,  ,, 
The  whole  quantity  (4000  grains)  will  consequently  have  lost  23*432 
grains,  which  has  been  absorbed  by  2000  grains  of  clay,  making  the  ab- 
sorption 1*1716  per  cent. 
When  simply  digested  with  the  solution  of  potash  in  the  cold 
the  clay  absorbed  1 * 050  per  cent,  of  potash.  When  the  materials 
are  boiled  together  the  absorption  is  somewhat  greater  or  (as 
above)  1*1716  per  cent.  This,  however,  is  not  a material  differ- 
ence. In  analytical  chemistry  it  is  usual  to  employ  caustic 
potash  as  a means  of  separating  silica  from  other  substances  with 
