334 



A thorough knowledge of the tension of carbonic acid, not 

 only in the sea, but in streams and springs would however be 

 of no small importance, since the solution of not a few pro- 

 blems of biological, hydrographical and perhaps geological and 

 meteorological interest depends upon it. It is for instance 

 most probable that the assimilation-energy of submersed plants 

 and the phyto-plancton is directly proportional to the tension 

 of carbonic acid in the water. It is certain that the rate of 

 dissolution of moUuscan shells is governed by the tension, 

 and it must be considered as probable that thick shells and 

 solid periostraca in some varieties of mussels may be accounted 

 for by their being a protection against an especially high 

 tension of carbonic acid in the surrounding water. From the 

 COg-tension of springs some information may possibly be 

 obtained about the strata through which they flow, and, last 

 but not least, the tension of carbonic acid in the ocean is the 

 factor governing the interchange of this gas between the air 

 and the water, and when the average tension of the ocean 

 becomes known, it will be possible to draw inferences respecting 

 the actual state of equilibrium — or want of equilibrium — of 

 this important component of our atmosphere^). 



In the summer of 1902 I accompanied my friend Mr. 

 M. PoRsiLD on an expedition to the Island of Disko on the west- 

 coast of Greenland, under the auspices of the Danish Com- 

 mission for the Geological and Geographical Investigation of 

 Greenland. I intended to study the respiratory exchange of 

 the organisms of the Arctic sea, and in order to do so I con- 

 structed an apparatus according to the principles mentioned 

 above for the determination of the tensions of the dissolved 



Inferences have indeed been made already, for instance by Chamberlin 

 and ToLMAN, (Journ. of Geol. vol. 7. 1899 pp. 544, 585, 667), but 

 from quite inadequate data, and it is a pity to see such vast masses of 

 knowledge and such acute reasoning as are brought to bear by these 

 Authors on assumptions that are really fictitious. 



