VOLUME XXIV NUMBER 8 



THE 



JOURNAL OF GEOLOGY 



NOVEMBER-DECEMBER igi6 



THE ROLE OF INORGANIC AGENCIES IN THE DEPOSI- 

 TION OF CALCIUM CARBONATE 



JOHN JOHNSTON and E. D. WILLIAMSON 

 Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 



Organic agencies are doubtless the predominant occasion of the 

 deposition of calcium carbonate, yet certain inorganic factors may 

 not safely be left out of account. The mode of action of the former, 

 which is in part a biological question, we shall not enter into, but 

 we shall limit ourselves to a discussion of the effects producible by 

 variation of certain inorganic factors which affect directly the solu- 

 bility of calcium carbonate. The question of the concentration of 

 calcium relative to the limiting saturation concentration of calcium 

 carbonate under the particular conditions — -in other words, the rela- 

 tive degree of saturation with respect to calcium carbonate — -has not 

 received adequate consideration; this is largely the consequence of 

 faulty data and of contradictory and erroneous statements regarding 

 the solubility of calcium carbonate under various conditions. It is 

 our purpose to direct attention to the quantitative effect, as deduced 

 from laboratory study, producible by variation of those factors 

 which, by affecting directly the degree of solubility of calcium car- 

 bonate, induce its precipitation from a solution saturated with it; 

 and to emphasize the fact that many of the points now ambiguous 

 may be settled by means of systematic and accurate investigation 



Vol. XXIV, No. 8 729 



