wells: solubility of calcite in water 



621 



Parts 

 CaCO^ 



A^illion 

 70 



60 



50 



40 



30 







JO 



20 



30 



40 



SO'C. 



Fig. 1. Solubility of calcite in water in contact with the atmosphere, and 

 its variation with temperature. 



The Mississippi River flows, on the average, in a direction of 

 rising temperature. Therefore, if the streams of the North 

 become saturated with calcium carbonate, a considerable amount 

 of it will tend to re-deposit as the river flows southward, merely 

 because of the rise in temperature. The chemical equation is: 



Ca(HC03)2 = CaCOs + COo + HoO 



from which it follows that carbon dioxide will be again evolved 

 as the calcium carbonate precipitates. The winds stir the at- 

 mosphere so rapidly, in comparison with the movement of the 

 river, that it is useless to look for variations of the carbon dioxide 

 in the atmosphere due to this cause. The water of the Missis- 

 sippi, however, seems to show clearly the decrease in bicarbonate 



