33 



The Advantages of Chemical Science (in an Agricultural 

 point of view,) illustrated by a series of Observations on 

 the Nature and Improvement of Soils, and on the Use 

 and Application of Manures : principally abridged from 

 Sir Humphry Davy's "Elements of Agricultural Che- 

 mistry." * 



Agricultural Chemistry has for its objects all those changes 

 in the arrangements of matter connected with the growth and 

 nourishment of plants, the comparative value of their produce 

 as food, the constitution of soils, and the manner in which 

 lands are enriched by manure, or rendered fertile by the differ- 

 ent processes of cultivation. — Inquiries of such a nature cannot 

 but be interesting and important both to the theoretical agri- 

 culturist and the practical farmer : to the first, they are neees- 

 sary in supplying most of the fundamental principles on which 

 the theory of the art depends; to the 6econd, they are useful 

 in affording simple and easy experiments for directing his la- 

 bours, and for enabling h'tu to pursue a certain systematic plan 

 of improvement. If land be unproductive, and a system of 

 ameliorating it is to be attempted, the sure method of obtain- 

 ing the object is by determining the cause of its sterility, which 

 must necessarily depend upon some defect in the constitution 

 pf the soil, and which may be easily discovered by chemical 

 analysis. Some lands of good apparent texture are still 

 sterile in a high degree, and common observation and common 

 practice afford no means of ascertaining the cause or of remov, 

 ing the effect; the application of chemical tests in such cases 

 is obvious, for the soil must contain some noxious principle 

 which may be easily discovered, and, probably, easily destroyed. 

 Are any of the salts of iron present, they may 'be decomposed 

 by lime ; is there an excess of siliceous sand, the system of 

 improvement must depend on the application of clay and cal- 

 careous matter ; is there a defect of calcareous ^matter, the 

 remedy is obvious; is an excess of vegetable matter indicated, 

 it may be removed by liming, paring, and burning; is there a 

 deficiency of vegetable matter, it is to be supplied by manure. 

 A question concerning the different kinds of lime-stone to be 

 employed in cultivation, often occurs ; to determine this fully, 

 in the common way of experience, would demand a considera- 

 ble time, perhaps some years, and trials which might be in- 



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• For (hit article w« art indebted to Mr, Gri»brook.— E»8. 



