THE FARMER AT HOME. 355 



electricity, according to Beccaria, unites the particles of hail more 

 closely than the more, moderate electricity does those of snow, in the 

 same manner as we see, that the drops of rain which fall from thun- 

 der clouds are larger than those which fall from others, though the 

 former descend through a less space. 



Were we to judge from appearances only, we might imagine that 

 so far from being useful to the earth, the cold humidity of snow would 

 be detrimental to vegetation. But the experience of all ages asserts 

 the contrary. Snow, particularly in those northern regions where the 

 ground is covered with it for several months, fructifies the earth, by 

 guarding the corn or other vegetables from the intenser cold of the 

 air, and especially from the cold piercing winds. It has been a vul- 

 gar opinion, very generally received, that snow fertilizes the land on 

 which it falls more than rain, in consequence of the nitrous salts, 

 which it is supposed to acquire by freezing. 



But it appears from the experiments of Margraaf, in the year 

 1731, that the chemical difference between rain and snow water is 

 exceedingly small ; that the latter is somewhat less nitrous, and con- 

 tains a somewhat less proportion of earth than the former ; but neither 

 of them contain either earth, or any kind of salt, in any quantity 

 which can be sensibly efficacious in promoting vegetation. Allowing, 

 therefore, that nitre is a fertilizer of land, which many are upon good 

 grounds disposed utterly to deny, yet so very small is the quantity of 

 it contained in snow, that it cannot be supposed to promote the vege- 

 tation of plants upon which the snow has fallen. The peculiar agency 

 of snow, as a fertilizer, in preference to rain, may admit of a very 

 rational explanation, without recurring to nitrous salts, supposed to 

 be contained in it. It may be ascribed to its furnishing a covering 

 to the roots of vegetables, by which they are guarded from the influ- 

 ence of the atmospherical cold, and the internal heat of the earth is 

 prevented from escaping. 



The internal parts of the earth are heated uniformly to the forty- 

 eighth degree of Fahrenheit's thermometer. This degree of heat is 

 greater than that in which the watery juices of vegetables freeze, and 

 it is propagated from the inward parts of the earth to the surface, on 

 which the vegetables grow. The atmosphere being variably heated 

 by the action of the sun in different climates, and in the same climate 

 at different seasons, communicates to the surface of the earth, and to 

 some distance below it, the degree of heat or cold which prevails in 

 itself. Different vegetables are able to preserve life under different 

 degrees of cold, but all of them perish when the cold which reaches 

 their roots is extreme. Providence has, therefore, in the coldest cli- 

 mates, provided a covering of snow for the roots of vegetables, by 

 which they are protected from the influence of the atmospherical cold. 

 The snow keeps in the internal heat of the earth which surrounds the 

 roots of vegetables, and defends them from the cold of the atmosphere. 

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