H4 ON THE CULTIVATrOK OF THE EARTH. 



" mining the cause of its sterility, which must 

 "necessarily depend upon some defect in the 

 " constitution of the soil, which may be easily 

 ** discovered by chemical analysis ; some lands 

 " of good apparent texture are yet sterile in a 

 " high degree, and common observation and 

 " common practice afford no means of ascer- 

 " taining the cause or removing the effect. 



" The application of chemical tests in such 

 ** cases is obvious, for the soil must contain some 

 " noxious principle, which may be easily dis- 

 ** covered, and, probably, easily destroyed. Are 

 " any of the salts of iion present ? They may be 

 " decomposed by lime. Is there any excess of 

 " siliceous sand ? The system of improvement 

 " must depend on the application of clay and 

 " calcareous matter. Is there a defect of c^- 

 " careous matter ? The remedy is obvious. Is 

 " an excess of vegetable matter indicated ? It 

 " may be removed by liming, paring, and burn- 

 " ing. Is there a deficiency of vegetable matter ? 

 ♦* It is to be supplied by manure.*' 



He also says, " The phenomena of vegetation 

 " must be considered as an important branch of 

 *' the science of organized nature ; but though 

 " exalted above inorganic matter, vegetables 

 •' are yet, in a gi-eat measure, dependant for 

 " their existence upon its laws. They receive 

 " their nourishment from the external elements; 



