The Hydrogen-ion Concentration, etc., of Sea-Water. 



57 



falls out of the capillary. A cover-glass is mounted on the capillary 

 with balsam. 



Before using the conversion table for converting millivolts into P H 

 a slight correction given in the following table was added to the 

 millivolt reading, on account of the rarefaction of the hydrogen. 



The above table is calculated on the hypothesis that the potential 

 of the hydrogen electrode in a normal solution of H ions depends on the 

 concentration and not solely on the pressure of the hydrogen. Hence 

 the value of the hydrogen electrode against the 0.1 n KC1 calomel 

 electrode is not 337 millivolts as used in case no correction for hydrogen 

 pressure has been applied, but a slightly higher value. The average 

 of the determinations listed by Clark and Lubs for temperatures up to 



Table for converting millivolts into PH at 10. 



Table for converting millivolts into PH at 30. 



