THE SOLUBILITY OF CALCITE IN SEA-WATER IN CONTACT 



WITH THE ATMOSPHERE, AND ITS VARIATION 



WITH TEMPERATURE. 



By Roger C. Wells, 

 Physical Chemist, U. S. Geological Survey. 



The gist of the present paper is that certain equilibria, whose attain- 

 ment would be expected from laboratory experiments, do not seem to be 

 fully attained under natural conditions in the ocean. The equilibria 

 referred to involve the effect of temperature on the exchange of carbon 

 dioxide between sea-water and the atmosphere and the precipitation or solu- 

 tion, as the case may be, of various solid constituents from or into sea- 

 water. Apparently, the adjustments occur so slowly and the bulk of the 

 ocean is so great, with reference to the surface exposed to the atmosphere, 

 that the expected variations with temperature do not appear in the water 

 of the open ocean. 



In a previous paper 1 it has been shown that the solubility of calcite in 

 water in contact with the atmosphere is a function of the temperature. 

 Further determinations seemed desirable for sea-water and have now been 

 made, using a portion of the water collected at Fowey Rocks Light, outside 

 Biscayne Bay, on the east coast of Florida, July 19-25, 1915. The com- 

 posite of daily samples showed, on analysis by A. A. Chambers, 19.93 parts 

 per thousand of chlorine. It is a pleasure to thank Mr. R. B. Dole for his 

 kindness in contributing this definite sample of sea-water. 



Table 1. — Calcite added to sea-water at i° C. and air passed daily. 



The method of experimentation was exactly similar to that described 

 in the previous paper. The water, in contact with an excess of calcite, was 

 agitated by a current of outdoor air for long intervals at different tem- 

 peratures and the dissolved carbonates determined by titration with 0.02 

 normal NaHS0 4 , using methyl orange as indicator. 



The results obtained are shown in tables 1 and 2. They are stated as 

 "carbonates per liter" and, on account of the uncertainty of the base, in 

 terms of equivalents, one equivalent per liter constituting the usual normal 

 solution. 



316 



'Jour. Wash. Acad. Sci., vol. 5, 617 (1915). 



