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



41 



The determination of CO2 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 CO9 tension of the air is read from figure 6. In order to hasten 

 equiHbrium 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 tahle for finding the CO2 tension of sea-water at 30° from the 

 Ph- This figure is explanatory of figure 6. The broken line is to he disregarded. 

 (From Jour. Biol. Chem., 1916, xxviii. 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 

 CO2 content of the air is the CO2 tension X 760 ^ (the barometric read- 

 ing—manometer 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. 



