363 



3. The influence of temperature upon the tension. Suppose 

 that the tension of a water is determined at 15^ and that it 

 is thereupon cooled down to 0"^ in a closed vessel. If the 

 chemical equilibrium remains unaltered by this process the 

 quantity of free carbonic acid, as well as the alkalinity and the 

 total quantity of CO.^. will remain unchanged. But the same 

 quantity of free carbonic acid in the water will, at the altered 

 temperature, correspond to a lower tension on account of the 

 altered coefficient of absorption: 



d = 



«15 б») 5 «„ б^о 



, hence 6*0 



вг 



Uib 



10000 10000' 



The formula indicates that if d is unaltered the tensions 

 will vary in the inverse ratio of the coefficients of absorption. 



By an experimental study of the variation of the tension 

 with the temperature I have obtained the following results: 



of seawater for many liours without cau.'^ing any appreciable decrease 

 in the tension. It cannot be doubted that the free carbonic acid is by 

 this process rapidly removed, but if we assume that it is very slowly 

 renewed by breakins up of the bicarbonates the phenomenon become? 

 quite intelligible. 



The results published by Ditt.m.m: in the Encyclopœdia Britannien 

 must be explained in this way. Огггмак found the quantities of carbonic 

 acid corresponding to low tensions of the gas much too great, simply 

 because the water did not, in his experiments, attain the state of equili- 

 brium, and this explanation also account.« for the discrepancy between 

 his several determinations. 



