M. De Gaspariii oh the Cimsificatlon of Soils. 89 



tain carbonates of lime and magnesia are eminently qualified 

 to in-oduce wheats and legimiinous crops ; the siliceous-clay 

 lands are the soils peculiarly adapted to forests ; the siliceous 

 are proper for plants which vegetate in winter, as rye, 

 &c. ; mould favours the vegetation of those pot-herbs which 

 are cultivated for the stems, leaves, &c. As regards the 

 facility or difficulty of working soils, those that are siliceous 

 are easily dressed, as well as those which have an organic 

 origin ; whilst calcareous and clayey present great differences 

 in this respect, according to the diversity of their composi- 

 tion. Finally, sandy and calcareous soils require frequent 

 manuring, and this addition they decompose to the imme- 

 diate profit of the plants, whilst clayey ones retain the manure, 

 may have the process of manuring postponed to greater intei'- 

 vals, and receiving at the same time a larger quantity of 

 manure. Diluvian soils admit of improvement with gypsum. 

 and siliceous clays with marl ; Avhilst lands rich in organic 

 matters require the dung of animals to facihtate and promote 

 the decomposition of the mould. 



Thus, we find in the mineralogical characters we have exa- 

 mined in detail, whether physical or geological, certain rela- 

 tions with the agricultiu-al characters. There are whole 

 groups of soils whose natural characters answer to those agri- 

 cultural characters, and reproduce properties which are com- 

 mon to them all. After having recognised and distinguished 

 them, we must next recognise those of them which from their 

 importance and generality will most naturally form the pri- 

 mary groups. 



§ II. Relative Value of Characters. 



For the appreciating of the relative value of the agricultu- 

 ral characters which we have enumerated, it is necessary to 

 discover which amongst them is the most indispensable, and 

 those whose absence would be most hurtful to agriculture* : 

 the degree of their importance and necessity will then indicate 

 the relative subdivisions. 



The appropriation of lands to the different kinds of culti- 

 vation seems to possess these qualities in the highest de- 

 gree ; and here, in fact, must begin every kind of agricul- 



