g£ ANALYSIS OF SOILS. 



of the fame kind, and in this cafe, one analyfis will be fuffi- 

 cient ; but in vallies, and near the beds of rivers, there are 

 very great differences, and it now and then occurs that one 

 part of a field is calcareous, and another part filiceous; and 

 in this cafe, and in analogous cafes, the portions different 

 from each other fhould be feparately fubmitted to experiment, 

 and preferved if Soils when collected, if they cannot be immediately ex* 

 needful. amined, mould be preferved in phials quite filled with them, 



and clofed with ground glafs ftoppers. 



The quantity of foil molt convenient for a perfect analyfis, 

 is from two or four hundred grains. It fhould be collected in 

 dry weather, and expofed to the atmofphere till it becomes dry 

 to the touch. 

 The fpecific The fpecific gravity of a foil, or the relation of its weight 



gravity t that of water, may be afcertained by introducing into a 



phial, which will contain a known quantity of water, equal 

 volumes of water and of foil, and this may be eafily done by 

 pouring in water till it is half full, and then adding the foil 

 till the fluid rifes to the mouth ; the difference between the 

 weight of the foil and that of the water, will give the refult. 

 Thus if the bottle contains four hundred grains of water, and 

 gains two hundred grains when half filled with water and half 

 with foil, the fpecific gravity of the foil will be 2, that is, it 

 will be twice as heavy as water, and if it gained one hundred 

 and fixty-five grains, its fpecific gravity would be 1825, water 

 being 1000. 

 Is ofimportancc It is of importance, that the fpecific gravity of a foil fhould 

 to be known. ^ j tnown> as lt affords an indication of the quantity of animal 

 and vegetable matter it contains; thefe fubftances being always 

 moft abundant in the lighter foils. 

 Other phyfical The other phyfical properties of foils fliould likewife be ex- 

 properties. amined before the analyfis is made, as they denote, to a cer- 



tain extent, their compofition, and ferve as guides in directing 

 the experiments. Thus filiceous foils are generally rough to 

 the touch, and fcratch glafs when rubbed upon it ; aluminous 

 foils adhere ftrongly to the tongue, and emit a ftrong earthy 

 fmell when breathed on ; and calcareous foils are foft, and 

 much Ids adhefive than aluminous foils. 



V.Modt 



