50 ERRONEOUS VIEWS OF AUTHORS. 



in the soil. These effects generally are caused Iby beds of fossil 

 sea-shells, which in some places reach the surface, and are* thus 

 exposed to the plough. These spots (which are the only super- 

 calcareous or chalky soils of this region) are not often more than 

 thirty feet across, and their nature is generally evident to the eye ; 

 and if not, is so easily determined by chemical tests, as to leave no 

 reason for confounding the injurious and beneficial effects of cal- 

 careous earth. This exception to the general fertilizing effect of 

 this ingredient of our soils would scarcely require naming, but to 

 mark what might be deemed an apparent contradiction. But this 

 exception, and its cause, must be kept in mind, and considered as 

 always understood and admitted throughout all my remarks, and 

 which therefore it is not necessary to name specially, when the 

 general qualities of calcareous earth are spoken of. [After all, this 

 exception is only in appearance, as it is found only in super-cal- 

 careous soils, and never in any soil in which calcareous earth is not 

 so abundant as to form a physical material. 1849.] 



In the beginning of this chapter, I advanced the important fact 

 that none of our poor soils contain naturally the least particle of cal- 

 careous earth. So far, this is supported merely by my assertion and 

 all those who have studied agriculture in books will require strong 

 proof before they can give credit to the existence of a fact, which 

 is either unsupported, or indirectly denied, by all written authority. 

 Others, who have not attended to such descriptions of soils in 

 general, may be too ready to admit the truth of my assertion 

 because, not knowing the opinions on this subject heretofore re- 

 ceived and undoubted, they would not be aware of the importance 

 of their admission. 



It is true that no author has said expressly that every soil con- 

 tains calcareous earth. Neither perhaps has any one stated that 

 every soil contains some silicious or aluminous earth. But the 

 manner in which each one has treated of soils and their constituent 

 parts, would cause their readers to infer that neither of these three 

 earths is ever entirely want/ing or at least that the entire absence 

 of the calcareous is as rare as the absence of silicious or aluminous 

 earth. Nor are we left to gather this opinion solely from indirect 

 testimony, as the following examples, from the highest authorities, 

 will prove. Davy says, "four earths generally abound in soils, the 

 aluminous, {he silicious, the calcareous, and the inagnesian;"* and 

 the soils of which he states the constituent parts, obtained by 

 chemical analysis, as well as those reported by Kirwan, and by 

 Young, all contain some proportion (and generally a large propor- 

 tion) of calcareous earth. ) Kirwan states the component parts of 



* Davy's Agr. Chem., Lecture 1. 



f Agr. Chem., Lect. 4. Kirwan on Manures; and Young's Prize Essay 

 on Manures. 



