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Nothing can be more simple than the chemical opera- 

 don 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 pro- 

 cess of fermentation ? and this question is still a sub- 

 ject of discussion ; but whoever will refer to the sim- 

 plest principles of chemistry, cannot entertain a doubt 

 on the subject. As soon as dung begins to decom- 

 pose, it throws off its volatile parts, which are the 

 most valuable and most efficient. Dung which has fer- 

 mented, so as to become a mere soft cohesive mass, 

 has generally lost from one third to one half of its 

 most useful constituent elements. It evidently should 

 be applied as soon as fermentation begins, that it may 

 exert its full action upon the plant, and lose none of 

 its nutritive powers. 



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 Chemistry 

 with Agriculture is not founded on mere vague specu- 

 lation, but that it offers principles which ought to be 

 understood and followed, and which in their progres- 

 sion and ultimate results, can hardly fail to be highly 

 beneficial to the community. 



A view of the objects in this Course of Lectures, 

 and of the manner in which they are to be treated, 

 will not, I hope, be considered as an improper intro- 

 duction. It will inform you what you are to expect ; 



