AGRICULTURE WITH CHEMISTRY. 161 



in the soil the attenuated vegetable and animal substan- 



jces, as also the mineral oil. Of this description are those 



s 



clays, or clayey loams, which have been deposited by the 



sea or muddy streams, containing a considerable propor- 

 tion of the exuviae, or remains of animal and vegetable 

 bodies, in an extreme degree of attenuation. Such 

 soils as these are the most permanently fertile, and 

 where the climate is favourable, produce the heaviest 

 and best filled grain. Soils formed by depositure, for the 

 most part contain a sufficient quantity of calcareous 

 matter. Adding lime to such lands may prove injurious, 

 by its expending, taking up, or otherwise altering the 

 arrangement and combination of the animal and vegeta- 

 ble matters, which should carefully be preserved for suc- 

 ceeding crops. Under any circumstances, lime should be 

 given to such soils but sparingly. 



There are clayey soils containing little or no animal, 

 vegetable, or bituminous matter, and which are equally 

 deficient of calcareous matter, consisting only of clay, sand, 

 and the earth of iron. To improve and render fertile a soil 

 of this description, is truly an herculean task, and will 

 seldom repay the industry of the cultivator, unless situ- 



x ated 



