AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 747 



relative values for the different conditions are probably good even 

 if the absolute values are inaccurate. According to the table, the 

 concentration of total C0 2 in water at constant temperature varies 

 practically as the cube root of P, for the small values of P; in other 

 words, a change of 3 per cent in the present proportion of C0 2 (e.g., 

 from 3.1 to 3 . o parts per 10,000) will produce a change of but 1 per 

 cent in the concentration of total C0 2 in the sea-water. Likewise 

 under present conditions (i.e., P— 0.0003) the total C0 2 in the ocean 

 decreases about 1 . 5 per cent of its value for each degree of rise in 

 temperature. At the higher pressures of C0 2 the proportion of free 

 C0 2 in the water becomes relatively much more important; but a 

 hundred-fold increase in the proportion in the adjacent air would 

 cause only a fivefold increase in the total C0 2 in the sea. In this 

 estimate and in the subsequent discussion, be it noted, the assump- 

 tion is implicit that the water is continuously saturated with CaC0 3 

 at 1 5 for all values of P, which in turn implies that conditions were 

 such that the rivers transported to the sea sufficient lime to achieve 

 this. On this basis, therefore, if the present amount of C0 2 in the 

 atmosphere were increased a hundred fold, the total amount of C0 2 

 in atmosphere and ocean would be only six times as much as it is 

 now; the conditions of equilibrium always being such that a chance 

 in the proportion of C0 2 in the atmosphere is minimized, not through 

 a permanent change in the proportion of free C0 2 in the sea (and 

 of its alkalinity), but ultimately by means of the precipitation or 

 solution of a definite quantity of CaC0 3 . 



Let us now make a computation of the ratio of the total amount 

 of C0 2 in the whole ocean to that in the whole atmosphere, this being, 

 of course, a measure of the capacity of the ocean to regulate the pro- 

 portion now present in the atmosphere. We assume again that the 

 ocean as a whole would be saturated with CaC0 3 if its temperature 

 were 15 , 1 and that its mean depth is 3,600 meters; 2 on this basis the 

 mean amount of C0 2 under each square meter of surface of the sea 

 is 81X3,600 gm. or 290 kg. The mean amount above each square 



1 This is just equivalent to the assumption that the average proportion of CaC0 3 

 throughout the ocean is that which corresponds to its solubility at 15 , about 60-70 

 parts CaC0 3 per million for values of P not far removed from 0.0003. Cf. Table I. 



2 See Encycl. Brit., article "Ocean." 



