380 



I have made only a few determinations of the tension in 

 springs and wells and all of these in that part of the country 

 where the deep layers consist of limestone , while the upper 

 strata are generally rich in this mineral, but they are sufficient 

 to demonstrate the very high tensions that may obtain in waters 

 which have oozed through limestone for so long a period that 

 they must be supposed to be completely saturated with calcium- 

 carbonate. 



Well carried down In the upper strata of 

 the solid limestone. Water very abun- 

 dant 



The same well 



Another well very neai' the first but not 

 so deep. Yield of water rather small 



Copenhagen Water-works | 



Considerable quantities of Ca CO. ^ are carried away by waters 

 such as come from the limestone-rocks, and the spacious caves 

 found everywhere in such rocks are thereby easily accounted for. 

 At the same time the problem arises: Whither is this carbonate 

 of lime carried, where and when is it deposited? 



') The quantities of dissolved carbonate of lime are computed from Schloe- 

 siNus formula (given above p. 368) on the assumption that the waters were 

 saturated with the salt at the tension found. It must however be 

 remembered that it is uncertain whether the formula holds good for 

 solutions of amorphous limestone, and that the figure 13 for the physi- 

 cally dissolved Ca CO-^ is certainly too small. 



') On seeing these high figures for the tension of waters coming from 

 limestone 1 suspected that the rock itself, being of organic origin, 

 might possibly contain bicarbonates and give rise to a tension of its 

 own when treated with pure, CO^-free, water. \ therefore tested my 

 suspicion on fresh hmestone, obtained from a quarry, and on pulverized 

 shells of mussels, but the result was absolutely negative. The shells, 

 as well as the limestone, did not contain any bicarbonates. 



