361 



The degree of accuracy of the tension-determinations is 

 not more than 0.1, and the vahies found for С up to and 

 inchiding tlie tension of 2.95 must therefore be said to corre- 

 spond in a remarkable degree, but at the higher tensions the 

 constant rapidly declines and has become negative at the tension 

 of 29.5. 



At the low tensions tJie result of the experiment is in 

 strict accordance with the theoretical assumption, so that we 

 may regard the loose carbonic acid as combined exclusively 

 with carbonates of divalent bases, that is with lime and mag- 

 nesia. At tensions above 3.0 the quantity of loose carbonic 

 acid becomes greater than that claimed by the theory, and 

 above a tension of 29 it exceeds the normal carbonate. In 

 order to explain this remarkable phenomenon we must bear in 

 mind the extreme complexity of the seawater-components and 

 especially the small quantities of weak acids, boracic, phosphoric, 

 arsenic etc., that are found in it. The salts of these weak 

 acids must necessarily be partially decomposed by the free car- 

 bonic acid, the quantity and tension of which being thereby 

 diminished M. 



^) During the writing of this chapter I began to suspect that there might 

 be some connection between the alkalinity of the «standard» water and 

 the excess of carbonic acid found at higher tensions over and above 

 the quantities demanded by theory. If some weak (organic) acid is pro- 

 duced by the decay of organisms the alkalinity will be lowered, but a 

 certain tension of carbonic acid will, on the other hand, cause a disso- 

 ciation of the salts of such an acid. In order to examine the point in 

 question I determined the alkalinity of a sample of " standard» water 

 poisoned, when being taken, with 1 gr. of sublimate per 1. It was found 

 to be decidedly higher than that of the unpoisoned water, viz. 23.1, though 

 the specific effect of sublimate upon the alkalinity causes it to decrease 

 (the alkalinity of the standard water decreased from 22.7 to 22.0 upon 

 the addition of 1 grm. of sublimate). The result indicates therefore 

 that decaying organic substances may cause an appreciable decrease of 

 the alkalinity of seawater, but the matter obviously needs further 

 investigation. 



