88 GENERAL SCIENCE 



pounds. In freezing it expands about one-tenth of its 

 volume, and a cubic foot of the ice that is formed (not the 

 whole of the cubic foot of water) weighs about fifty-seven 

 pounds. The density of ice is about nine-tenths that of 

 water. This explains why ice as it forms on the surface of 

 water in winter does not sink to the bottom, and why ponds 

 and streams do not become frozen solid during a winter. 

 If large bodies of water did freeze solid, it is unlikely that 

 this ice would ever thaw very much below the water surface. 

 The heat of the summer's sun upon it would be used largely 

 in vaporizing the surface layer of water. All marine life 

 would be destroyed, and the waters would be icy cold all 

 summer. Winds blowing over this ice cold water would 

 check or destroy the growth of vegetation. With the den- 

 sity of ice so nearly that of water, it is calculated that about 

 nine-tenths (.92) of the volume of an iceberg is submerged 

 however much it towers above water surface. Within a 

 temperature range from 32 to 212 F. (o to 100 C.) water 

 exists as solid, liquid, and vapor. No other substance has 

 so narrow a range in temperature for all three states. 



All waters coming out of the ground are likely to contain 

 more or less of minerals in solution. Inland lakes and seas 

 such as the Great Salt Lake of Utah, whose waters have no 

 outlet other than by evaporation, become increasingly 

 saline as minerals in solution are washed in to be left there. 

 The waters of the ocean contain nearly 3 per cent of 

 common salt. " Mineral springs" contain certain dissolved 

 compounds that have more or less of medicinal value. 

 Usually these waters as sold on the market are " car- 

 bonated, " i.e., made to hold under pressure considerable 

 carbon dioxide gas. When this water is poured into an 

 open glass, and is under only the ordinary atmospheric 

 pressure, effervescence occurs by reason of the escape of 

 this gas into the air. 



