MEASUREMENT OF SALII^ITY OF SEA WATER 



17 



tions on a given sample consuming about 10 minutes. The indica- 

 tions were that the method would give results of about the same 

 order of accuracy as a hydrometer and that for use on board ship 

 it would require weather of about the same degree of smoothness as 

 that required for the satisfactory use of a hydrometer. 



PiQ 7, — Electrolytic cell used for preliminary measurements of resistance 

 of sea-water samples of various salinities 



METHODS FOR LABORATORY USE 



In addition to the methods described in the preceding, two very 

 precise methods are available. They are not applicable on board 

 ship but can be used in the laboratory. These are the pycnometer 



