28 



At 25°C, and with 1 .0 M KCl as electrolyte, the measured total re- 

 sistance of the glass capillary cell GCC-2 varied by less than 0.003% as the 

 electrolyte level in the cell was varied from the top to the bottom of the reser- 

 voir. Inasmuch as this error lies within the experimental deviation, the con- 

 clusion is drawn that the measured resistance is independent of the position of 

 the hydraulic fluid -electrolyte interface in the capillary-type cell. 



G. DETERMINATION OF CELL CONSTANTS 



Cell constant measurements were made with the cells both in the bath 

 and within the pressure vessel. Measurements and computations involving KCl 

 were based on the procedures and results of Jones and Bradshawj (■'■^) while for 

 NaCl and sea water the cell constants were computed from the specific conduct- 

 ances reported by Chambers, Stokes, and Stokes, C I'*) and Thomas, Thompson, 

 and Utterback.(15) The results of these measurements are summarized in 

 Table VII. In the case of the Jamieson cell (TJC-1), the measured cell constant 

 was only in fair agreement with that calculated from cell dimensions, probably 

 due to the nonparallelism of the electrodes; in the case of the glass capillary 

 cells (GCC-1) and (GCC-2), the agreement was good. 



The deviations in cell constant in Table VII are somewhat greater 

 than is desirable in conductivity measurements of the highest precision. Also, 

 for GCC-2, the values determined using KCl are about 8% greater than the val- 

 ues determined using sea water or 0.500 M NaCl. In the case of GCC-2, the 

 large cell constant and the upper limit of the conductivity bridge's capacity pre- 

 vents cell constant determinations using dilute KCl solutions . Because of these 

 difficulties and the spurious parallel resistance effect discussed above, in order 

 to get entirely self-consistent results and to make the present results compatible 

 with the 1 atmosphere values now being used by ocean ographers, we decided to 

 base our calculations on cell constants as determined immediately before and 

 after each pressure run and using the electrolyte of the run . In the case of the 

 sea water run, this procedure makes the correctness of the specific conduct- 

 ances we report contingent upon the 1 atmosphere values reported by Thomas, 

 Thompson, and Utterback.(15) 



The accuracy of the results of Thomas, Thompson and Utter back has 

 been questioned on several occasions. In particular, Pollak(l°) has suggested 

 that their results may be in error due to a Parker effect . In the event that more 

 accurate values for the specific conductance of sea water become available, the 

 values which we report for specific conductances can be readily corrected simply 

 by multiplying by the factor Kjj/K^;^^, where Kj^ is the new value of the specific 

 conductance and K^j^ is the value reported by Thomas, Thompson, and Utterback 

 at the same chlorinity and temperature . The values of the constants in the em- 

 pirical equations which we will generate subsequently for expressing the specific 

 conductance at elevated pressure in terms of the 1 atmosphere value will be un- 

 affected, inasmuch as the above correction factors out., 



artlmr B.lLittU3nt. 



S-700 1-0307 



