ADVERTISEMENT. 



DURING ten years, since 1802, 1 have had the 

 honour, every Session, of delivering Courses of Lec- 

 tures before the Board of Agriculture. I have endea- 

 voured, at all times, to follow in them the progress of 

 chemical discovery ; they have therefore varied every 

 year : and such is the rapidity with which Chemistry 

 is extending, that some alterations and improvements 

 were rendered necessary at the time they were prepar- 

 ing for the press. 



The Duke of Bedford has enabled me to stamp a 

 value upon this work, by permitting me to add to it the 

 results of the experiments instituted by His Grace 

 upon the quantity of produce afforded by the different 

 grasses. 



I am indebted for much useful information to 

 many members of the Board ; of which acknowledg- 

 ments will be found in the body of the work. If there 

 are any omisssions on this head, I trust they will be 

 attributed to defect of recollection, and not to any 

 want of candour or of gratitude. 



Where I have derived any specific statements from 

 books, I have always quoted the authors ; but I have 



