746 



JOHN JOHNSTON AND E. D. WILLIAMSON 



last factor — apart altogether from the influence of C0 2 as an agency 

 disintegrating the rocks — we have calculated the concentration of the 

 free and combined C0 2 in sea-water at three temperatures for several 

 proportions of C0 2 in the atmosphere. The specific assumptions 

 made in these calculations are: (a) that the molar absorption coeffi- 

 cient (c) of C0 2 is the same as in a o . 6 N (3 . 5 per cent) solution of 

 sodium chloride; (b) that the water is always saturated with respect 

 to calcite, so that we are justified in using the solubility-product 

 constant (K' c ) corresponding to the temperature; (c) that the degree 

 of ionization of the carbonate is o. 6, a value which is probably high 

 rather than low. 1 On this basis the formula becomes 



A = total C0 2 = cP+ V 1 1 2oocA:£P/o . 6, 



where the first term represents the free C0 2 and the second the total 

 combined C0 2 , each expressed in moles per liter; whence by multi- 

 plication by the factor o . 044 one obtains the result in grams C0 2 

 per cubic meter (parts per million) as given in Table III. 



TABLE III 



The Concentration of Free (/), Combined (b), and Total (.4) CO2 — Expressed 

 in Grams CO2 per Cubic Meter (Parts per Million) — in Sea-Water at 

 Several Temperatures and Several Partial Pressures (P) of CO2 in the 

 Atmosphere; Calculated on the Basis of the Specific Assumptions Men- 

 tioned Above 



The figures for total C0 2 , derived in this way, are in substantial 

 agreement with the results of analyses of sea-water; in any case the 



1 Murray and Hiort (The Depths of the Ocean [1912], p. 175) estimate the aggregate 

 degree of ionization in sea-water to be 0.9; but this is undoubtedly much too high. 



