AGRICULTURAL MUSEUM 253 



fa'^e, and examined as to the similarity of their proper- 

 ti s. It sometimes happens, that upon plains the wholes 

 of the u »per stratum of the land is of the same kind, 

 and in this case, one analysis will be sufncient ; hut 'm 

 V allies, and near the beds of rivers, there are veiy 

 great differences, and it now and then occurs that one 

 part of a held is caicareous, and an.other part siliceous; 

 ar.d in this case, and in analog-ous cat-es. the portiotis 

 dilierent from each other shcuid be sepaiately submitted 

 to experiment. 



Soils when collected, if they cannot be immediately 

 examined, should he pre^ei-ved in phials quite filled with 

 them, and closed with ground glass stoppers. 



The quantity of soil most convenient for a perfect 

 analysis, is from two to four hniidred <.Mains. It shoidd 

 be collected in di-y we;;ther, and exposed to the atmos- 

 phere till it becomes dry to the touch. 



The specific gravity of a soil, or the relation of its 

 weight to that of water, moy be ascertained by introduc- 

 ing itUo a phial, wlsich will contain a known quantity of 

 water, equal volumes of waterand of soil, and this may 

 be easily done by pouring in water till it is half full, and 

 then adding the soil till the fluid rises to the moiith ; the 

 ditference between the weight of the soil and that of tlie 

 water will give the result. Time, if the bottle contains 

 four hundred grains of water, and gains two hundred 

 grains when iiali" filled with water and half with soil, 

 the specific gravity of the soil will be 2, that is, it will 

 be twice as heavy as water, and if it gained one hun- 

 dred and sixty five grains, its s])ecific gi-avity would be 

 1825, water being 1000. 



It is of importance, that the specific gravity of a soil 

 should be known, as it affords an indication of the quan- 

 tity of animal and vegetaljle matter it contains ; these 

 substances being always most abundant in the lighter 

 soils. 



