wells: solubility of calcite in watee 



619 



calculated from the result of titrating about 50 cc. with 0.02 N 

 NaHS04, using methyl orange as indicator. The solutions were 

 slightly acid toward phenolphthalein, thus showing that the 

 calcium was present chiefly as bicarbonate. The results are 

 stated, however, in terms of CaCOs, since that is the solid phase 

 actually dissolved, or the phase that would be again precipitated 

 on evaporation. Table I contains some results obtained at 1°C, 

 when calcite in excess was added to water and air was passed 

 through the solution for an hour or two daily. 



TABLE I 



Calcite Added to Distilled Water at 1°C. and Air Passed Daily 



Table II shows how slowly a supersaturated solution, without 

 points of crystallization other than the walls of the flask, loses its 

 excess CO2 and CaCOs at 1°. The high results of this series 

 are probably due in part to the deposition of a more soluble 

 form of calcium carbonate than calcite and were excluded in 

 drawing the curve below. In Table III are shown results ob- 

 tained with a similar solution but with considerable powdered 

 calcite present to assist deposition. 



TABLE II 

 Air Passed at 1" Through a Solution Containing CO2 and Ca(HC03)2 



