40 Nature of Aquatic Environment 



The thermal conservatism of water Water is slower 

 to respond to changes of temperature than is any other 

 known substance. Its specific heat is greater. The 

 heat it consumes in thawing (and liberates in freezing) 

 is greater. The amount of heat necessary to melt one 

 part of ice at o C. without raising its temperature at all 

 would be sufficient to raise the temperature of the same 

 when melted more than 75 degrees. Furthermore, the 

 heat consumed in vaporization is still greater. The 

 amount required to vaporize one part of water at 100 C. 

 without raising its temperature would suffice to raise 

 534 parts of water from o C. to i C. ; and the amount 

 is still greater when vaporization occurs at a lower 

 temperature. Hence, the cooling effect of evaporation 

 on the surrounding atmosphere, which gives up its 

 heat to effect this change of state in the water; hence, 

 the equalizing effect upon climate of the presence of 

 large bodies of water; hence the extreme variance 

 between day and night temperatures in desert lands; 

 hence the delaying of winter so along after the autumnal, 

 and of summer so long after the vernal equinox. 

 Water is the great stabilizer of temperature. 



The content of natural waters Water is the common 

 solvent of all foodstuffs. These stuffs are, as every- 

 body knows, such simple mineral salts as are readily 

 leached out of the soil, and such gases as may be washed 

 down out of the atmosphere. And since green plants 

 are the producing class among organisms, all others 

 being dependent on their constructive activities, water 

 is fitted to be the home of life in proportion as it con- 

 tains the essentials of green plant foods, with fit condi- 

 tions of warmth, air and light. 



Natural waters all contain more or less of the elemen- 

 tary foodstuffs necessary for life. Pure water (H 2 O) 

 is not found. All natural waters are mineralized 

 waters even rain, as it falls, is such. And a compara- 



