132 
On the Chemical P/V])crtics of Soils. 
Ninth Series. — Retention of Ammonia from a Solution 
OF Chloride of Ammonium. 
The soil used in this series of experiments was the same as 
tliat employed in the Third Series. 
The solution of sal-ammoniac contained 211"40 grains of am- 
monia in the gallon, or 3"02 grains in 1000 of liquid. lb. 
of soil and 7000 grains of solution of sal-ammoniac of this strength, 
M ere mixed together, and the amount of ammonia absorbed by the 
soil ascertained as before. The whole quantity of soil absorbed in 
this experiment 5'60 grains of ammonia. 1000 grains thus sepa- 
rated 3'20 grains of ammonia from the solution of sal-ammoniac. 
Here again we observe that the amount of ammonia which a 
soil is capable of removing from st)lutions of ammoniacal salts 
depends upon the strength of the li(juid with which it is brought 
into contact. 
The soil was next Avashed four times with 7000 grains of water, 
and the proportion of ammonia removed in each washing deter- 
mined as before : Ammonia. 
Grains. 
The first washing remove<l -409 
The second , , , , •G46 
Thethh-d ,, ,, -811 
The fourth -499 
2-3G5 
28,000 grains of water thus removed 2 "365 grains of ammonia 
from lb. of soil, which in the first place absorbed 5'GO grains 
of ammonia from a strong solution of sal-ammoniac. After 
washing with a considerable (quantity of water, the soil thus retained 
3"235 grains of ammonia, instead of 5'(jO grains. 
Thus,whether a soil has absorbed free ammonia, or ammonia 
from a solution of sulphate of ammonia or sal-ammoniac, water 
passed through it will wash out a certain quantity of ammonia. 
Jlut in each case the power of a soil to retain ammonia is very 
much greater than its inclination to yield it again to water. 
It is hardly necessary to remind the reader that in tlie absorp- 
tion experiments with salts of ammonia the acid of the salt passes 
through the soil in combination with lime or f)ther mineral 
matters of the S(nl, whilst the ammonia alone is retained. I may 
notice, however, that the watery li([uid which passes through a 
soil when solutions of ammoniacal salts are fdtered through it, 
contains a larger quantity of viiiicral matters than is the case when 
pure water is filtered through the soil. It would thus appear 
that ammoniacal salts have the property of rendering the mineral 
matters of the soil soluble. But the details of experiments on 
this subject, and an account of their bearing on agriculture, 
must be reserved for a future communication. 
