30 On the Chemical Properties 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 

 that 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. J- Ib. 

 of soil and 7000 grains of solution of sal-ammoniac of this strength, 

 were 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 solutions of ammoniacal salts 

 depends upon the strength of the liquid with which it is brought 

 into contact. 



The soil was next washed 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 removed '409 



The second ,, ,, -646 



The third ,, ,, -811 



The fourth ,, ,, -499 



2-3G5 



28,000 grains of water thus removed 2*365 grains of ammonia 

 from J Ib. of soil, which in the first place absorbed 5*60 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*60 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. 

 But 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 the absorp- 

 tion experiments with salts of ammonia the acid of the salt passes 

 through the soil in combination with lime or other mineral 

 matters of the soil, whilst the ammonia alone is retained. I may 

 notice, however, that the watery liquid which passes through a 

 soil when solutions of ammoniacal salts are filtered through it, 

 contains a larger quantity of mineral 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. 



