Liquid Manure. 
151 
The changes which took place in the chemical constitution of 
the liquid manure in contact with this soil are similar to those 
noticed in the first and second experiment. It will be seen, 
however, that the power of this loamy soil to absorb ammonia 
and potash is not equal to that exhibited by the pasture land and 
by the calcareous clay from Cirencester. Thus, in the experi- 
ment before us, 20,000 grains of loamy fertile soil absorbed 9-74 
grains of ammonia ; or 1000 grains absorbed "487 ; whilst 1000 
grains of Cirencester soil absorbed -738 of ammonia, and 1000 
grains of pasture land, •737. 
We also find a smaller proportion of potash retained by the 
loamy soil than by the Cirencester soil and by the pasture land. 
It thus seems probable that soils which absorb much ammonia 
also absorb much potash. 
Again, we find that some lime, though sparingly present in 
the soil, is taken up by the liquid manure ; and that nearly the 
total amount of chloride of sodium of the original liquid passes 
unaltered into the liquid which was left in contact witli this soil 
for three days. Other minor changes may be passed over 
unnoticed, as they agree with previous results on which some 
observations have been made already. 
It will be noticed that none of the four soils used in these 
experiments had the power of absorbing completely the whole of 
the ammonia, potash, or phosphoric acid contained in the liquid 
manure. A certain amount of these constituents always remained 
in the liquid which was left in contact with soil. As the liquid 
manure contained a good deal of ammonia and potash, it may be 
urged that the quantity of soil employed in the experiments in 
relation to that of the liquid was insufficient for the purpose of 
complete absorption. But this argument certainly does not hold 
good in the case of phosphoric acid, and probabl}' not in the case of 
ammonia or potash. With respect to phosphoric acid, I can speak 
positively on the subject, fori have filtered through the same soils 
a very much larger proportion of phosphoric acid, and found 
that nearly the whole of it was retained by three of the soils. 
But whether a solution containing much or little phosphoric acid 
be filtered through a moderately stiff soil, invariably some phos- 
phoric acid passes into the filtered liquid. Again, if a dilute 
solution of a soluble phosphate is passed through a soil, it may be 
ascertained readily that there is phosphoric acid in the filtered 
liquid. If now a fresh quantity of a solution containing phosphoric 
acid be shaken with the soil through which the first soluti(m has 
passed, it will be found that the soil takes up a fresh quantity of 
phosphoric acid. This circumstance appears to me to prove 
decidedly that soils have not the power of rendering soluble phos- 
phates so completely insoluble that these compounds cannot enter 
