CONTENTS. 



PART I. HISTORICAL INTRODUCTION. 



PAGE 



Beginning of agricultural chemistry ...... 4 



Early theories regarding plant-growth 4 



Van Helmont ......... 4 



Digby 6 



Duhamel and Stephen Hales ...... 8 



Jethro Tull 9 



Charles Bonnet's discovery of source of plants' carbon . . 11 

 Researches of Priestley, Ingenhousz, Se'ne'bier, on assimilation 



of carbon H-12 



Publication of first English treatise by Earl Dundonald . . 13 

 Publication of Theodore de Saussure, * Chemical Researches on 



Vegetation,' 1804 . . .14 



Theories on source of plant-nitrogen . . . . .15 



Early experiments on this subject 16 



Sir Humphry Davy's lectures (1802-1812) .... 17 



State of agricultural chemistry in 1812 . . . . .17 



Beginning of Boussingault's researches (1834) .... 21 



Publication of Liebig's first report to the British Association . 24 

 Refutation of " humus" theory ..... 26 



Liebig's mineral theory ....... 26 



Liebig's theory of source of plants' nitrogen ... 27 



Publication of Liebig's second report to British Association . 30 



Liebig's services to agricultural chemistry . . .31 



Development of agricultural research in Germany ... 32 



The Rothamsted Experiment Station ..... 33 



