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genial heat of the soil, particularly in spring, must be 

 of the highest importance to the rising plant. And 

 when the leaves are fully developed, the ground is 

 shaded; and any injurious influence, which in the sum- 

 mer might be expected from too great a heat, entirely 

 prevented: so that the temperature of the surface, 

 when bare and exposed to the rays of the sun, affords 

 at least one indication of the degrees of its fertility; and 

 the thermometer may be sometimes a useful instru- 

 ment to the purchaser or improver of lands. 



The moisture in the soil influences its tempera- 

 ture; and the manner in which it is distributed through, 

 or combined with, the earthy materials, is of great 

 importance in relation to the nutriment of the plant. 

 If water is too strongly attracted by the earths, it will 

 not be absorbed by the roots of the plants; if it is in 

 too great quantity, or too loosely united to them, it 

 tends to injure or destroy the fibrous parts of the 

 roots. 



There are two states in which water seems to 

 exist in the earths, and in animal and vegetable substan- 

 ces: in the first state it is united by chemical, in the 

 other by cohesive attraction. 



If pure solution of ammonia or potassa be poured 

 Into a solution of alum, alumina falls down combined 

 with water; and the water dried by exposure to air will 

 afford more than half its weight of water by distilla- 

 tion; in this instance the water is united by chemical 

 attraction. The moisture which wood, or muscular 

 hbre, or gum, that have been heated to 212, afford 

 by distillation at a red heat, is likewise water, the ele- 



