WESTERN DISTRICT. 285 



Most soils, if not all, yield soluble silica when thus acted upon by water. Sometimes it 

 is inappreciable ; at others, susceptible of an accurate determination. This substance, 

 without doubt, is one of the essential elements of good grass or pasture land. All the 

 cereals require silica, as much as they do carbon : hence, where there is a deficiency of 

 soluble silica, we can not hope to obtain good crops of hay or grain. I omit here all 

 details, except the common statement in regard to silex, reserving a more special notice 

 of this substance for a future section. 



The Marcellus shales, when subjected to the solvent power of water, furnish considerable 

 soluble matter. Thus, 200 grains, treated as above, gave 



Soluble matter 1 -98 grs. 



Organic mattter 0-63 



Saline matter 1-35 



The latter was composed of 



Silex 0-03 



Alumina or phosphate of alumina tinged with iron, -25 



Chlorides of lime and magnesia 0-23 



Sulphate of lime 0-12 



Carbonate of lime 0*73 



1-35 



A specimen of soil from the cornfield referred to above, treated in the usual method of 

 analysis, gave 



Water of absorption 4 • 15 



Organic matter 5-06 



Silex 80-15 



Carbonate of lime 3-00 



Magnesia 0-50 



Peroxide of iron and alumina 7-00 



99-86 



A specimen of soil which has never been cultivated, taken from the same geological 

 position as the above, gave 



Water of absorption 5-20 



Organic matter 6-50 



Silicates 89-05 



Peroxide of iron and alumina 7 -64 



Carbonate of lime 2-05 



Magnesia 0-25 



104-69 



