PREFACE TO FIRST EDITION. 



For several years courses of instruction have been 

 given at the University of Minnesota to classes of 

 young men who intend to become farmers and who 

 desire information that will be of assistance to them 

 in their profession. In giving this instruction mimeo- 

 graphed notes have been prepared, but the increase 

 in the number of students and the volume of notes 

 necessitate the publication of this work. In its prep- 

 aration, it has been the aim to give, in condensed 

 form, the principles of chemistry which have a bear- 

 ing upon the conservation of soil fertility and the 

 economic use of manures. 



HARRY SNYDER. 

 UNIVERSITY OF MINNESOTA, 

 COLLEGE OF AGRICULTURE, 



ST. ANTHONY PARK, MINN. 

 April 75, 1899. 



