680 



THURAS: RECORDING SEA-WATER SALINITY 



ply. No change in conductivity was obtained up to a flow of as 

 high as 1 hter per minute. 



The efficiency of washing out the cell was obtained by use of 

 two solutions, one having a salinity of 35 and the other a salinity 

 of 32. These solutions were passed through the cell simultane- 

 ously and the resistance of the cell was measured at definite in- 

 tervals. For a slow flow (100 cc. per minute) the cell washed 

 out to within 0.01 of the salinity of the second solution, after 

 400 cc. of this solution had been used. For a rapid flow this 

 degree of washing-out was attained with only 300 cc. of the solu- 

 tion. This is much better than was obtained in the preliminary 

 experiments on other cells; and is sufficiently rapid for the maxi- 

 mum change in salinity which occurs in the ocean. 



<b 



nj 



Fig. 1. Bridge resistances 



A few experiments to find the effect of air bubbles showed that 

 bubbles on the back of the electrodes caused no change in con- 

 ductivity and bubbles up to 3 mm. in diameter just in front of 

 the electrodes gave no change in conductivity. A bubble 2 mm. 

 in diameter in one of the tubes gave a change in conductivity 

 corresponding to 0.01 in salinity. By tilting the cells 15 degrees 

 any bubbles which might form in the cells will come to the sur- 

 face above the electrodes. 



