PHASE PHENOMENA IN CALCITE-SEAWATER SYSTEM 



199 



200 400 



PRESSURE, atm 



600 



Fig. 7 Dissolution behavior in 18.7% seawater. 



third experiment. Ratios of calcium to magnesium as plotted in Fig. 9 were the 

 amount of calcium present in the calcite column by weight divided by the 

 amount of magnesium present in the column by analysis. The amount of 

 magnesium incorporated by the uptake of a given quantity of seawater without 

 any incorporation of magnesium through precipitation should approximate the 

 amount taken up in the run made at 389.9 atm. In a comparison of the 

 incorporation of 389.9 atm with the value that would result if no precipitation 

 took place, a reactor containing 1.7020 g of calcite was allowed to become 

 saturated with Sargasso water (this same reactor, containing the column of 

 calcite, was used in all the experiments). The increase in weight that resulted 

 from this saturation was 3.01 g. This amount of Sargasso water would be 

 expected to increase the amount of magnesium in the reactor by 4.01 mg, in 

 good agreement with the experimental value for the highest pressure sample. The 

 Ca/Mg ratio for the saturation sample was 169.8, compared with 168.4 in the 

 highest pressure sample. Thus the incorporation of magnesium in the calcareous 

 precipitated materials is inversely proportional to the pressure at which they are 

 formed. 



