CLIMATE 45 



it will be warmer than before it was placed in the hot water. 

 If a lump of melting ice is placed in the vessel of hot water 

 and then removed, the ice will not be warmer than before, 

 but there will be less of it. The heat of the water has been 

 used in melting the ice, not in changing its temperature. 



If, on a bitter cold day, a pail of snow is brought into a 

 warm room and a thermometer is placed in the snow, the 

 temperature rises gradually until 32 F. is reached. Then it 

 becomes stationary, and the snow begins to melt. If the pail 

 is put on the fire, the temperature still remains 32 F., but the 

 snow melts more rapidly. As soon as all the snow is completely 

 melted, however, the temperature begins to rise and rises 

 steadily until the water boils, when it again becomes station- 

 ary and remains so during the passage of water into vapor. 



We see that heat must be supplied to ice at o C., or 32 F., 

 in order to change it into water, and further, that the tem- 

 perature of the mixture does not rise so long as any ice is pres- 

 ent, no matter how much heat is supplied. The amount of 

 heat necessary to melt I gram of ice has been measured, and 

 has been found to be 80 calories. It takes 80 times as much 

 heat to melt I gram of ice at o C. as it does to raise the tem- 

 perature of I gram of water i C. 



If one steps into the snow above the shoe tops, the legs are 

 immediately chilled. This is because the snow in melting 

 takes heat from the body. 



Climate. Heat must be supplied to ice to melt it. On 

 the other hand, water, in freezing, loses heat, and the amount 

 of heat lost by freezing water is exactly equal to the amount 

 of heat absorbed by melting ice. Because water loses heat 

 when it freezes, the presence of large streams of water greatly 

 influences the climate of a region. In winter the heat from 

 the freezing water keeps the temperature of the surrounding 

 air higher than it would naturally be, and consequently the 



