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the concentrated principles of such be obtained through 

 other channels, and used more economically and directly 

 upon our lands ? An answer to this enquiry opens up 

 the whole subject of the value and use of special or 

 concentrated fertilizers, and this is a subject which has 

 been so often and so fully discussed by theorists and 

 others, that the reader will not thank me for going over 

 the ground again. Upon no subject connected with ag- 

 riculture does a wider difference of opinion prevail, and 

 the discussion of the subject in the usual unsatisftictory 

 empirical way does not tend to settle disputed points, or 

 clear away the clouds of doubt which hang around the 

 whole matter. Experiment usually decides controverted 

 points in matters of physical enquiry, and it is capable 

 of reaching this end in the subject under consideration, 

 but it must be made carefully, intelligently, and be long 

 continued. Having entered upon a series of experiments 

 of this nature with the determination to make no report 

 for at least five years, or until soils could be carried 

 through a period long enough to observe the effects of 

 disturbing influences, and also learn something regarding 

 the growth of different crops, and the lasting effects of 

 peculiar modes of treatment, I find myself at a point of 

 time when it is proper to examine and make known re- 

 sults. The time and space allowed me in this essay do 

 not admit of detailed statements, and such must be re- 

 served for another channel of communication, if health 

 and strength permit. 



The experiments have been made upon a farm of about 

 eighty acres, which was purchased in 1863 with the 

 view of entering upon a course of experimental enquiry 

 interesting to agriculturalists. The question deemed 

 most important to decide was, whether a run-down farm 



