CHAPTER V 



WATER SOLVENT ACTION OF WATER DRINKING WA- 

 TERSPRINGSSHALLOW WELLS DEEP WELLS- 

 TEMPORARY HARDNESS PERMANENT HARDNESS- 

 HOUSEHOLD WATER 



40. Properties of Water. The two gaseous elements, 

 hydrogen and oxygen, have a strong chemical attraction 

 each for the other. They unite whenever possible in the 

 proportions of two volumes of hydrogen to one volume 

 of oxygen, and, by weight, in the proportion of one unit 

 of hydrogen to eight units of oxygen, to form water, which 

 is one of the most stable of compounds. 



Water is possessed of remarkable physical and chemical 

 properties. In common with most liquids, its volume 

 changes with heating and cooling. When water is cooled, 

 Hs maximum density is attained at the temperature of 

 4 Centigrade. This temperature is still 4 above the 

 freezing temperature of water. At a lower temperature 

 than 4, water again expands, and at zero, when it freezes, 

 it again expands suddenly. This latter expansion accounts 

 for the disintegrating effects of freezing, the force being 

 so powerful that it will split large rocks, and it also accounts 

 for the fact that ice will float. This remarkable abnormal 

 expansion of water, when the temperature falls from 4 

 C. to C., results in the formation of ice at the surface 

 of a cool ng body rather than throughout its mass. When, 

 by the radiation of heat into the air, the temperature at 

 the surface of a body of water is cooled to 4 C., at which 

 temperature it is densest, the cooled surface layers will 

 continue to sink till the entire mass has reached the tem- 

 perature of 4 C. Should the water grow still cooler, by 



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