6 
cation, whether as a manure for different soils, or 
as a cement, determined. 
Peat earth of a certain consistence and compo- 
sition is an excellent manure ; but there are some 
varieties of peats which contain so large a quantity 
of ferruginous matter as to be absolutely poisonous 
to plants. Nothing can be more simple than the 
chemical operation for determining the nature, 
and the probable uses of a substance of this kind. 
There has been no question on which more dif- 
ference of opinion has existed, than that of the 
state in which manure ought to be ploughed into 
the land ; whether recent, or when it has gone 
through the process of fermentation ? and this 
question is still a subject of discussion : but who- 
ever will refer to the simplest principles of che- 
mistry, cannot entertain a doubt on the subject. 
As soon as dung begins to decompose, it throws 
off its volatile parts, which are the most valuable 
and most efficient. Dung which has fermented, 
so as to become a mere soft cohesive mass, has 
generally lost from one-third to one-half of its 
most useful constituent elements, and that it may 
exert its full action upon the plant, and lose none 
of its nutritive powers, it should evidently be ap- 
plied much sooner, and long before decomposition 
has arrived at its ultimate results. 
It would be easy to adduce a multitude of other 
instances of the same kind ; but sufficient, I trust, 
has been said to prove, that the connexion of Che- 
mistry with Agriculture, is not founded on mere 
vague speculation, but that it offers principles 
