PHYSIOLOGY: J. F. McCLENDON 
689 
ON THE HYDROGEN ION CONCENTRATION OF SEA WATER, 
AND THE PHYSIOLOGICAL EFFECTS OF THE IONS 
OF SEA WATER 
By J. F. McClendon 
DEPARTMENT OF PHYSIOLOGY. UNIVERSITY OF MINNESOTA. AND TORTUGAS 
LABORATORY. CARNEGIE INSTITUTION OF WASHINGTON 
Received by the Academy, November 10, 1916 
Both natural sea water at Tortugas, Florida, of salinity of 35-36 
per kilo and artificial sea water of the following composition were studied: 
Normal solutions or Isotonic solutions. 
CaCl2 0.5 m. 22.07 cc. 0.38 m. 29.0 cc. 
MgClz 0.5m. 50.21 cc. 0.37 m. 67.9 cc. 
MgS04 0.5 m. 57.09 cc. 0.975 m. 29.5 cc. 
KCl 1.0 m. 10.23 cc. 0.577 m. 17.7 cc. 
NaCl 1.0 m. 483.65 cc. 0.568 m. 852.0 cc. 
NaBr 1.0 m. 0.80 cc. 0.565 m. 1.4 cc. 
NaHCOg 1.0 m. 2.40 cc. 0.93 m. 2.58 cc. 
H20 373.63 cc, 0.00 cc. 
1000.00 cc. 1000.00 cc 
The mixture was aerated many hours or until it reached the proper 
alkalinity. It was tested by placing the most delicate marine organisms 
in it, which were found to live and behave normally. 
The excess of non-volatile base over mineral acid in Tortugas sea 
water was found by Dole to be 0.002265-0.00253 N. per kilogram, and 
my own observations fall within these limits. That of various artificial 
sea waters studied was 0.00225-0.00245 Normal per kilogram. This 
variation in natural sea water is independent of the salinity and is 
apparently associated with the variation in the lime content. 
The hydrogen ion concentration will be indicated by the minus log- 
arithm or PH, the PH of pure water, or neutral solution, at 23° being 
7, that of n. HCl ca. 0, and that of n. KOH ca. 14. The PH was 
determined by the hydrogen electrode and standardized instruments, 
the special apparatus being described by McClendon and Magoon^ 
All measurements were made at 30°. The PH of Tortugas sea water 
was found to vary from 8.1 to 8.22 and this variation was found to be 
partly due to the variation in the excess base but largely due to varia- 
tions in the CO2 tension. 
The PH of sea water at known CO2 tensions was studied and it was 
found that, as the CO2 tension decreased, the ratio of change in PH with 
change in CO2 tension increased so that the PPI could be much more 
accurately measured than the CO2 tension. The CO2 tension of the 
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