AGRTCUT.TURAL MUSEUM 253 



greatest de-f;Tcc absorbent, and retentive of wafer, and 

 win gcnoi'aliy be found to contain a large proportion of 

 aluminous earth. When the loss is only from 20 to 10, 

 tlie land may be considerefl as only slightly absorbent 

 and retentive, and the siliceous earth as most abundant. 



VL Of xx^R Separation of Stones, Gravkl, and 



VEGETABLE FlBRES FROM SoiLS. 



None of the loose stones, gravel, or large vegetable 

 fibres should be divided from the pare soil till after the 

 water is drawn off; lor tliese bodies are themselves 

 often highly absorbent anfl retentive, and in consequence 

 influence the fertility of the luiui. Vh^^ next pro ess, 

 however, after that of h.-aling, should be their separa- 

 tion, which ma}' be easily aceo nplished f)y the sieve, 

 after the soil has been gently bruised in a mortar The 

 \\'eights of the vegetable tibres or wood, and of the gra- 

 vel and stones, should be separately noted dow •, and 

 the nature of the last ascertained ; if calcareous, they 

 will effervesce with acids; if siliceous, they will be suf- 

 iiciendy hard to scratch glass; and if of the common 

 aluminous class of stones, they will be soft, easily- 

 scratched with a knife, and incapable of elfervescing 

 with acids. 



VII. SEPARATiON OF THE SaND AND ClAY, OR LoA]\I., 

 FROM eA^CH other. 



The greater number of soils, besides gravel and 

 ttones, contain larger or smaller proportions of sand 

 of different degrees of fineness; and it is a necessary 

 operation, the next in the process of analysis, to detach 

 them from the parts in a slate of more minute division, 

 such as clay, loam, marie, and vegetaldc and animal 

 matter. This may be etTected in a waj' sul^-'icntly ac- 

 curate, by agitation of the soil in water. In this case, 

 the coarse sand v\ ill generally separate in a minute, and 

 the finer in two or three minutes, whdst the mhiuteiy 



