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



41 



The determination of C0 2 of the air is made by placing about 10 c.c. 

 of natural or artificial sea-water containing the thymolsulfophthalein 

 in a nonsol test-tube of exactly the same bore as the sealed tubes and 

 bubbling air through it to equilibrium and comparing with the tubes. 

 The C0 2 tension of the air is read from figure 6. In order to hasten 

 equilibrium the test-tube should be tall and have a series of constric- 

 tions above the portion necessary for colorimetry. A rubber stopper 



FIG. 11. Conversion table for finding the COz tension of sea-water at 30 from the 

 P H - This figure is explanatory of figure 6. The broken line is to be disregarded. 

 (From Jour. Biol. Chem., 1916, xxvin, 135.) 



with 3 holes is inserted and a glass tube leading to the bottom, its 

 closed end being pierced by fine holes; a tube is connected to a suction 

 pump and a mercury manometer inserted in the third hole. The 

 CO 2 content of the air is the C0 2 tension X 760 -f- (the barometric read- 

 ingmanometer reading). Thymolsulfophthalein is decolorized by 

 bubbling air through its solution for a long time, but this seems not 

 to be an oxidation or a reduction. 



