XVlll EDITOR'S PREFACE TO THE 



The Editor has endeavored to eiFect this change. 

 In doing so, it was necessary to retain the original 

 character of the work ; hence those alterations only- 

 have been made which are calculated to render the 

 work more generally useful. It must be remember- 

 ed, that the object of the author was not to write a 

 '^ System of Agricultural Chemistry," but to furnish 

 a " Treatise on the Chemistry of Agriculture." It 

 is to be hoped, that those who are acquainted with 

 the general doctrines of Chemistry will find no diffi- 

 culty in comprehending any of the principles here 

 developed. 



The author has enriched the present edition with 

 many valuable additions ; allusion may be particular- 

 ly made to the practical illustration of his principles 

 furnished in the supplementary Chapter on Soils. 

 The analyses of soils contained in that chapter will 

 serve to point out the culpable negligence exhibited 

 in the examination of English soils. Even in the 

 analyses of professional chemists, published in detail, 

 and with every afi'ectation of accuracy, the estima- 

 tion of the most important ingredients is neglected. 

 How rarely do we find phosphoric acid amongst the 

 products of their analyses ? potash and soda would 

 appear to be absent from all soils in the British ter- 

 ritories 1 Yet these are invariable constituents of 

 fertile soils, and are conditions indispensable to their 

 fertility. 



It is necessary to state, that all additions and alter- 

 ations, with a few unimportant exceptions, have been 



