I 



369 



The theoretical results of the present chapter may be 

 summarized as follows: 



The alkali in seawater consists almost exclusively of car- 

 bonates of alkaline earths, especially of lime and probably in a 

 less degree of magnesia. To a certain extent these carbonates 

 are chemically combined with carbonic acid, and bicarbonates 

 are thus formed. The tension of the water at a given tempe- 

 rature depends upon the relation between the quantities of 

 bicarbonate and of normal carbonate, and up to a tension of 

 about 3 (at a temperature of 15°) the process is in perfect agree- 

 ment with the theoretical dissociation-formula. At tensions 

 above this point secondary processes come into play. These 

 secondary processes involve the chemical combination of more 

 carbonic acid than demanded by theory, and they most probably 

 consist in the partial replacing of certain weak acid by carbonic 

 acid, in their salts. 



The tension of a given seawater rises with the temperature, 

 chiefly because the coefficient of absorption and consequently 

 the tension corresponding to a given quantity of free carbonic 

 acid is thereby altered, but also, partly, because the affinity 

 between normal carbonate and free carbonic acid decreases 

 with the rising temperature. 



