n, the base only being retained, and the acid
escaping most commonly in combination with lime. Thus, if sulphate of
ammonia be employed, the water which flows from the soil contains
sulphate of lime, and if muriate of ammonia be used, it is muriate of
lime which escapes.

This absorbent action is most remarkably manifested in the case of
ammonia and potash, but it takes place also with magnesia and soda. With
the latter, however, it is incomplete, only a half or a fourth of the
soda being removed from solution, the difference depending to some
extent on the acid with which it is in combination. The extent to which
absorption takes place varies also with the nature of the soil, and the
state of combination of the substance used. Exact experiments have
hitherto been chiefly confined to ammonia, potash, and lime in the free
state, and as bicarbonate; and the following table gives the results
obtained by Way, with solutions containing about 1 per cent of these
substances in solution:--

-----------------------------------------------------------------------------
| | Loamy | Red soil,| Pure | Subsoil |
| | soil, | Berkshire.| clay. | clay, |
| |Dorsetshire.| | | Somersetshire.|
------------------------|------------------------|----------|---------------|
|Ammonia, caustic | 0.3438 | 0.1570 | ... | ... |
| " from muriate | 0.3478 | 0.1966 | 0.2847| 0.0818 |
|Potash, caustic | ... | ... | 1.050 | 2.087 |
| " from nitrate | ... | ... | 0.4980| ... |
|Lime, caustic | ... | ... | 1.468 | ... |
| " from bicarbonate | ... | ... | 0.731 | ... |
------------------------|------------|-----------|----------|---------------

From these numbers it appears that very great differences exist in the
absorbent power of different soils, the first of those experimented on
being capable of taking more than twice as much ammonia as the second,
and nearly four times as much as the subsoil clay. It appears also, as
far as absorption goes, to be immaterial whether the ammonia is free or
combined. But it is different with potash, which is absorbed from the
nitrate to the extent of about O.6 per cent, and from a caustic solution
of potash to double that amou