PREFACE vii 



The following pages will show the author's special 

 indebtedness to the writings of Hilgard, King, Wollny, 

 Mayer, Schloesing, and Lawes and Gilbert. The 

 splendid work of Hilgard upon the soils of Mississippi 

 and California must be regarded as in many respects 

 a typical investigation ; it needs to be repeated in 

 every English county. 



The frontispiece to the present volume is the por- 

 trait of John Sibthorp, M.D., F.R.S., Sherardian and 

 Regius Professor of Botany in the University of 

 Oxford ; it is copied from the oil painting in the 

 Botanical Library. Dr. Sibthorp was the founder of 

 the Chair of Rural Economy in the University. He 

 died in 1 796, after a short life spent in active research. 



Should the present volume meet with a favourable 

 reception, it is the author's intention to publish a 

 continuation of the work, in which some of the chief 

 points in the chemistry of soil may be discussed on 

 a similar plan. 



R. WABINGTON. 



Harpenden, October, 1899. 



