404 
The Injliience of Lime on the 
bonate of ammonia contained in the atmosphere with which the 
soil was in contact, and, as in the previous case, the action was 
referred to the presence of one or other of tliese double silicates 
in the soil. But an essential difference here presented itself. 
Ammonia could be removed by soils from solution in water, in 
virtue of tlieir ccmtaining either the double lime or double soda 
silicate — the two substances of the class supposed to be most 
usually present; wliereas it was found that the lime-salt 
alone was capable of removing ammonia from its atmospheric 
solvent.* In several soils that I examined, a good deal of the 
double silicate of soda was present, and it seemed probable that 
its conversion into the corresponding lime-salt would put the soil 
into a better condition for absorbing ammonia from the atmos- 
phere. Now, as the natural fertility of soils is evidently, in 
some very distinct way, connected with this absorption of atmos- 
pheric ammonia, it will at once be seen that a very important 
part would thus be found for lime to play in enabling the soil 
in a given time to absorb a large amount of the valuable alkali. 
In this view the application of lime would, in fact, be indirectly 
a manuring with ammonia. With the wish of ascertaining how 
lar this suppositif)n was correct, I commenced the series of 
experiments which I am now about to describe. The results do 
not indeed altogether bear out the expectations with which they 
were undertaken, but they are of much interest : in the first 
place, as exhibiting the wonderful extent to which a soil is 
capable of storing up for the use of plants the gaseous ammonia 
of the air ; and secondly, in suggesting an explanation of the^ 
action of lime very different, it is true, from that which led to 
the experiments, but still most worthy of consideration. 
This subject is, however, very far from being exhausted, and 
the results that have been obtained are only an instalment of 
what we may hope to arrive at by a further prosecution of the 
same line of research. 
Most of the soils used in these experiments were selected) 
from the land of Mr. Paine, at Farnham. It is obviously unim- 
portant, in the outset of a research of this kind, what particular 
kind of soil is operated upon. The motive in the selection was 
the facility offered by the active interest which Mr. Paine is 
known to take in such subjects, and his anxiety to forward them 
* I gave at tlnj time a chemical explanation of this circiimslaiice. AV hen double 
silicate of lime and alumina comes in contact ■with carbonate of ammonia, car- 
bonate of lime and the double ammonia salt are produced, and these arc com- 
patible with each other. Carbonate of soda, however, which would be produced 
in the other case, has actual!}- the power of decomposing double silicate of alumina 
and ammonia, which it does in consequence of the solubility of carbonate of soda 
and the volatility of carbonate of ammonia. The soda silicate cannot, therefore, 
tiike ammonia from carbonate of ammonia. 
