On the Analijsis of Soils. 29 



lion of neutral carbonate of potash, and nitrate of ammo- 

 nia. An account of the nature of these bodies, and their 

 etfccts, may be found in the chemical works already no- 

 ticed; and the reagents are sold, together with the instru- 

 ments mentioned above, by Mr. Knight, Foster Lane, 

 Cheapside, arranged in an appropriate chest. 



IV. Mode of collecting Soils for Analysis. 



In cases when the general nature of the soil of a field is 

 to be ascertained, specimens of it should be taken from 

 different places, two or three Inches below the surface, and 

 examined as to the similarity of their properties. Jt some- 

 times happens, that upon plains the whole of the upper stra- 

 tum of the landisof the same kind, and in this case one ana- 

 lysis will be sutficieiit; but in valleys, 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 siliceous ; and in this case, and in analogous cases, the 

 portions different from each other should be separately sub- 

 mitted to experiment. 



Soils, when collected, if thev cannot be immediately ex- 

 amined, should be preserved in phials quite filled with them, 

 and closed with ground glass stoppers. 



The quantity of soil most convenient for a perfect analy- 

 sis is from two to four hundred grains. It should be col- 

 lected in dry weather, and exposed to the atmosphere till it 

 becomes dry to the touch. 



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

 to thai of water, may be ascertained by introducing into a 

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

 volumes of water and of soil ; and this n)ay be easily done 

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

 soil till the fluid rises to the mouth ; the difference between 

 the weight of the soil and that of the water will give the 

 result. Thus, if the bottle contains- four hundred grains 

 of water, and gains two hundred grains when half filled 

 with water and half with soil, the specific gravity of the 

 soil will be two, that is, it will be twice as heavy as water; 

 and if it trained one hundred and sixty-five grains, its spe- 

 cific gravUy would l)e 18^:3, water being 1000. 



It IS of importance that the specific gravity of a soil 

 ahould be known, as it affords an indication of the quantity 

 of animal and vegetable matter it contains ; these sub- 

 stances being always most abundant in the lighter soils. 



The other physical properties of soils should likewise be 



examined before the analysis is made, as they denote, to a 



2 certain 



