THE OCEAN 



169 



hydrogen ion concentration increased, and 

 the alkalinity accordingly diminished. 



The only variation from the truly remark- 

 able constancy of reaction of the ocean, so 

 far as we know, is in the case of the Black Sea. 

 But this sea, at depths below 180 meters, con- 

 tains sulphurous acid, which undoubtedly 

 accounts for the slight diminution of alkalin- 

 ity recorded in the table. This last obser- 



