WEIBEL AND THUUAS: RECORDING SALINITY 



147 



open cell. This can be done either by carrying standard samples 

 or by determining the salinity of the sea water flowing through 

 the open cell by some accurate method that can be used on board 

 ship. Such a method giving salinity by a measurement of den- 

 sity has been described.'^ A record of the resistance ratio of the 

 two cells is made by a recorder similar to those now in use for 

 measuring temperature, but some changes will have to be made 

 t(^ adapt it for using alternating current. 



Fig. 1. 



The new and important feature of this method is the use of 

 two cells containing liquids of nearly the same properties, which 

 make it possible to compensate almost completely for the large 

 temperature coefficient of sea water. The two cells are placed 

 in a uniform temperature bath and the error will bo only that 

 due to the small differential temperature coefficient of iho two 

 solutions. 



EXPERIMENTAL WORK 



Preliminary expoi-iments to test the general feasibility of the 

 method showed: 



1. Good balances can be obtained with a mnplc Wheatstone 



■'TiiunAs, A. L., Journ. Wash. Acad. Sci. 7: GO."). 1917. 



