CHAPTER II 



HYDROLOGY 

 1. PROPERTIES OF WATER 



Weight. The weight and specific gravity of water vary 

 somewhat, depending on its temperature and on the variou 

 impurities which it contains in solution or carries in suspension. 

 For pure water the weight may be considered practically constant, 

 as the maximum variation has been found to he so inconsiderable, 

 being only about 0.05 of 1 per cent. Its weight is now generally 

 assumed to be 62.355 pounds per cubic foot at a temperature of 

 62 F., although authorities differ somewhat about the exact 

 figure. Water of lakes and rivers will, under ^ordinary circum- 

 stances vary between 62.3 and 62.5 pounds, depending on the 

 impurities. Table XVI, however, shows that a considerable 

 variation may be expected under unusual conditions, as for exam- 

 ple, the Great Salt Lake, where the water, due to the large amount 

 which it contains, weighs nearly 73 pounds per cubic foot. 



TABLE XVI 



WEIGHTS AND SPECIFIC GRAVITY OP WATER 



While sometimes invisible, all natural waters always contain 

 in solution more or less of the substances which they have come in 



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