750 JOHN JOHNSTON AND E. D. WILLIAMSON 



words, the relative degree of saturation with respect to calcium car- 

 bonate in the ocean. The importance of this factor is obvious if we 

 recollect that the chance of a permanent deposit is, ceteris paribus, 

 greater the more nearly saturated the surrounding water is; its 

 neglect is doubtless due to the erroneous and misleading statements 

 as to the solubility of CaC0 3 which have been prevalent. The solu- 

 bility under specified conditions can now be calculated with the 

 requisite accuracy; it is affected materially by variations of tem- 

 perature and of concentration of free C0 2 such as occur in nature. 

 For example, a change in the proportion of C0 2 in the adjacent air 

 from 3 . 2 to 3 . o parts per io,ooo, or an increase of temperature of 

 2° C. would result ultimately in the precipitation of about 2 gm. 

 CaC0 3 from every cubic meter of a solution saturated with it. 

 Comparison of the solubility as calculated with the available ana- 

 lytical data indicates that the warmer surface layers of the sea are 

 substantially saturated with respect to calcite, and consequently that 

 precipitation is to be expected wherever the water is being warmed 

 or is losing C0 2 , or both, and this independently of any other 

 agencies. Indeed, these inorganic factors must be considered no 

 matter what may be the agency inducing precipitation; for example, 

 there is ground for believing that calcareous organisms are more 

 abundant the more nearly saturated with CaC0 3 the water is. The 

 view here advocated, that a somewhat greater role be assigned to the 

 inorganic factors than has hitherto been usual, does not conflict with 

 other views — it merely shifts the emphasis a little; nor does it con- 

 flict with any facts that have been definitely ascertained. Its precise 

 importance can be determined only by accurate determination of 

 temperature, salinity, and particularly of concentration of C0 2 — 

 free and total — -of the water carried out systematically over the 

 ocean; the results of such an investigation, properly carried out, 

 would have an important bearing on many outstanding biological, 

 as well as geological, problems. 



