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SCIENCES 

 LIBRARY 



PREFACE. 



The laboratory practices described in this manual are designed for 

 one semester's work, during which it is hoped to give the student a 

 knowledge of principles that underlie many common agricultural oper- 

 ations. No very complicated apparatus is required, but great care 

 must be used to have uniform conditions, especially where different 

 soils are to be compared. 



In this second edition many changes have been made that the 

 experience of the past three years seemed to indicate as best. Some 

 new Practices have been added, together with cuts, descriptions of 

 apparatus and forms for the data obtained. 



In a number of practices students may work together in groups 

 not so large, however, but that each one may have a distinct problem 

 to work out in each practice. This will enable the class to complete 

 the work in one semester which otherwise might not be possible. 



ACKNOWLEDGEMENTS. 



These laboratory practices were not all originated in the Univer- 

 sity of Illinois. Nos. 9, 11, 14, 18, 20, 21, and 22 have been adapted to 

 our work from Ohio State University Bulletin No. 6 by Professor 

 William D. Gibbs, formerly of that institution, and Practice 23 was 

 taken from the Manual of Soil Physics of Purdue University. A few 

 of the practices in this manual had been arranged for student use by 

 the late Mr. H. E. Ward, formerly instructor in Soil Physics in the 

 University of Illinois. 



I also wish to acknowledge the valuable suggestions received from 

 Professor Clifford Willis, now of South Dakota Agricultural College, 

 and Mr. A. F. Gustafson of this University. 



The Author. 

 College of Agriculture, 



University of Illinois, 

 Urbana, Illinois, June, 1908. 



