158 MAYOR— DETECTING OCEAN CURRENTS. 



The carbon dioxide tension of the sea water was calculated from 

 the true PH and the temperature according to the ratio determined 

 experimentally by McClendon, 1917, p. 36. McClendon found that 

 the PH of sea water normally declines .01 for 1° C. decline in tem- 

 perature. Thus if the PH is 8.22 at 28° it may be expected to be 

 8.21 at 2"]° C. I find this to be true under normal conditions, but if 

 the sea water is diluted with river water rich in CO2 or mingled 

 with large amounts of up-welling water from the depths, this rela- 

 tion may even be reversed. Thus in the Tropical Pacific I have 

 'observed a rise of 0.13 in the PH while the temperature sank 0.45° 

 C. In general, however, under normal conditions, McClendon's 

 rule holds good both for the Atlantic and the Pacific. 



The salinity of the sea water is expressed in grams of total salts 

 per 1,000 grams of water, and was determined by titration with 

 AgNOs, using KoCrO^ as indicator, and standard sea water obtained 

 from Professor Martin Knudsen for comparison. 



The thermometers read to %o° C. and were compared with a 

 thermometer standardized by the U. S. Bureau of Standards. 



The currents were determined by the drift of the ship from her 

 expected position. Naturally only a decided current could be de- 

 tected by this crude method, but it was the only one available. The 

 sea water was dipped up in a glass vessel from the stern of the vessel 

 and tested at once for hydrogen-ion concentration and temperature, 

 and a sample was preserved for determination of salinity. Experi- 

 ments showed that no contamination from the ship could be detected 

 if the water were dipped up from the stern rather than from the 

 bow, waste from the sides of the ship being forced away from the 

 stern by the back wave of the wake. 



Summary. 



Through the simple process of placing a few drops of the red 

 dye thymolsulphonephthalein in the bottom of a test tube and filling 

 the tube with sea water we can determine its hydrogen-ion concen- 

 tration. The more alkaline the water the more blue-green the color 

 while relatively acid water gives a yellowish-green color. 



In the Tropical Pacific the surface water drifting toward the 



