72 THE YEAR. 



any substance we can assist in dissolving 1 the ice into 

 water, or changing the water into vapour after it has 

 been formed, we may very much increase the degree 

 of cold. The substances so used are the frigorific or 

 freezing mixture of the chemists, and one of the ingre- 

 dients at least, must always be a solid in crystals, and 

 the real absorption of heat is required for the changing 

 of those crystals into a liquid. In ordinary cases there 

 is no other means employed by nature in the melting 

 of ice and snow, than the applying to them of a warmer 

 atmosphere, the action of the direct rays of the sun, or 

 the tumbling of them into water of a higher tempera- 

 ture. But the great quantity of heat that is required 

 for a solution in either of those ways, renders the opera- 

 tion a slow one, and thereby both prevents evil and 

 produces good. 



If, indeed, the change of ice to water had been in- 

 stantaneous at any temperature which is natural on the 

 surface of the globe, the effects of the spring would 

 have been tenfold more terrific than any phenomenon 

 of which one can think, other than that of the collision 

 of two planets in their annual career. The instant 

 congelation of every drop of humidity by the first 

 nipping of the autumnal frost, would not have been half 

 so fatal or so dreadful as the opposite change. On 

 every plain where snow could lie, the roots of all use- 

 ful vegetables would have been rotted, and the smaller 

 land animals killed, before the heat could have con- 

 verted the water into vapour. For a long time, indeed, 

 the difference of the night and the day would have 

 been intolerable ; the one all ice, and the other all 

 sludge ; and the incessant freezing and thawing, would 



