B6 M. De Gasparin oti the Classification of Soils. 



find that the tenacity of such soil is in proportion to the quan- 

 tity of the latter kind, except in a small number of cases. 

 6th, Upon examination with the microscope, it is ascertained 

 that these exceptions are owing to a coating of ferruginous 

 clay which adheres to the surfaces of the mineral particles, — 

 that washing separates it with difficulty, and that it serves as 

 a cement, forcibly agglutinating, and increasing the tenacity 

 of the whole. 



On the Principles of the Classification of Soils. 



If we study the objects which we find in nature, that we may 

 know them as they really are in themselves, under all the re- 

 lations of their organization and their properties, it is in their 

 innermost existence, — in the relation of their parts, — in their 

 resemblances and dissimilarities, that we must seek for the 

 means of grouping them together, without any regard to the 

 circumstances which are foreign to their peculiar and proper 

 existence. It is thus that Jussieu established the several fa- 

 milies of plants, Cuvier those of animals, and M. Beudant 

 his orders of minerals. Each of their groups collects toge- 

 ther the beings or the substances which bear the closest re- 

 semblance to each other, under all the appreciable relations 

 of their organization or of their texture, but without inter- 

 mingling therewith any idea concerning their utility, which 

 could only be considered as foreign to the subject; and this 

 forms pure natural history. 



But if we regard it in another point of view, if it be not 

 the being or the substance in itself which we wish to study, 

 but only such and such a property of the object, the classifi- 

 cation then ceases to be a natiu-al method or arrangement, 

 and becomes a common classification. Accordingly, when we 

 would study plants in an agricultural point of view, the con- 

 sideration of families should not mislead us ; as it would be 

 impossible to establish any one agricultural principle which 

 would be common to an entu'e family. That of the Gramineae, 

 for example, presents us with oats, wheat, rice, and the sugar- 

 cane, which require different cultures, and serve for very dif- 

 ferent purposes. Besides, the number of plants which are 



