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AGRICULTURAL TEXT-BOOK. 



contains one-third and more of its weight of water. Dr. Salis 

 bury gives the following tables exhibiting the per centage of 

 water, dry matter, and ash in the horse chestnut, (^Esculm hip- 

 pocastanum,) at Albany, N. Y., at two different periods : 



MAY , 1849. 



MAY 18, 1849 



67. The air in water is a mixture of the same constituents as 

 atmospheric air, but they are not present in the same propor 

 tions the air contained in water being much richer in oxygen, 

 and containing 32 per cent, of its volume of that element 

 (Knapp,) and in water from freshly melted snow 34.8 per 

 cent. The quantity of air retained by water at an altitude of 6 

 to 8000 feet is reduced to one-third of its usual proportion. 

 Hence fishes cannot live in Alpine lakes. 



63. Water contained in the soil may be so impregnated with 

 salts or organic acids as to destroy vegetation. Some of the 

 salts of iron are thus destructive. A cure may be effected by 

 thorough draining. Water containing the salts of lime is called 

 Hard Water. Its effect on horses is very remarkable. Hard 



