110 
On the Chemical Properties of Soils. 
bottle with 14,000 grains of ammonia solution, containing- 
23"24 grains of caustic ammonia in the imperial gallon. In the 
course of the day the bottle was repeatedly shaken, and the liquid 
then left to subside. After standing for three days the soil had 
all settled to the bottom, and the greater part of the liquid could 
be drawn off in a perfectly clear condition. This liquid Avas 
slightly tinged with yellow. 
2000 grains of this clear liquid were then carefully neuti-alised 
with a standard solution of sulphuric acid of known strength. 
It being known how much of the test acid was required to 
neutralise the ammonia solution before contact with soil, the 
amount of ammonia retained in the soil could be readily cal- 
culated : Ammonia. 
Grains. 
Before contact with the soil the solution contained in 
1000 grains -332 
After contact '135 
Difference -lOT 
•197 grains of ammonia were thus removed from each 1000 
grains of solution, consequently 2"758 grains of ammonia were 
removed from 14,000 grains of solution and retained in 3000 
grains of soil. 
In this experiment accordingly 1000 grains of soil ab- 
sorbed 'DIOS grains of ammonia. A repetition of the same 
experiment gave precisely the same results. The clear liquid 
poured off the soil being slightly yellow, it occurred to me 
that the organic matter (humus acids) in the soil possibly 
might have neutralised a small portion of the free ammonia 
of the ammoniacal liquid employed in the experiment. As 
the test^acid cannot indicate any ammonia when previously 
neutralised by the organic acids of the soil, the proportion of 
ammonia retained by the latter may be stated rather too high. 
In order to verify this supposition, I distilled some of the yellow- 
coloured liquid with caustic potash, in an apparatus which was 
so constructed that all chance of traces of potash being cairied 
over with the distillate was entirely avoided. The distillate was 
c ollected in a measured quantity of acid of known strength, and 
the amount of ammonia distilled over, carefully determined. 
Proceeding in this manner, 1000 grains of liquid, after contact 
with soil, contained '143 of ammonia. Before contact with soil 
it contained '332 grains. Consequently. 'ISO were removed 
from every 1000 grains of liquid, or 2 "646 were removed from 
the whole quantity of liquid employed in the experiment, and 
retained by 3000 grains of soil, or 1000 grains of soil absorbed 
"882 grains of .ammonia. Not taking into account the amount 
of free ammonia neutralised by the organic acids of the soil, 
