MEASUREMENT OF SALINITY OF SEA WATER 15 



OTHER METHODS FOR USE ON BOARD SHIP 

 ELECTRICAL CONDUCTIVITY METHOD 



Probably the most precise method for measuring the salinity of 

 sea water, either on board ship or in the laboratory ashore, is by the 

 electrical conductivity apparatus developed by Dr. Frank Wenner, 

 of the United States Bureau of Standards. This apparatus has 

 been used principally by Commander Edward H. Smith, United 

 States Coast Guard, and is described in Bulletin No. 12 of the Inter- 

 national Ice Observation and Ice Patrol Service in the North Atlan- 

 tic Ocean, Season of 1924. Although the apparatus is rather 

 expensive and more precise than the needs of the Coast and Geodetic 

 Survey require, so that it will probably not come into use in this 

 bureau, it gives salinity to five significant figures and is fairly con- 

 venient to use. For the details of this apparatus and the procedure 

 involved in its use, the reader is referred to the above-mentioned 

 publication of the Coast Guard. 



One of the early steps in the development of the Wenner appa- 

 ratus was the work of Weibel and Thuras, described in the Journal 

 of the Washington Academy of Sciences, Volume VIII, page 145, 

 1918. They describe, in this article, an electrical conductivity appa- 

 ratus, which when installed on board a ship will make a continuous 

 record of the salinity of the surface water passed through by the 

 ship. 



Dr. G. Gueben, of the University of Liege, Belgium, is doing 

 some interesting work in the measurement of the salinity of sea 

 water by electrical methods. It involves the measurement of the 

 specific conductivity of sea water in place; that is, by lowering a 

 pair of electrodes to the desired depth, and not by bringing up a 

 sample and measuring its conductivity on board. The work of 

 Monsieur and Madame Chauchard, published in the Comptes Kendus 

 de I'Academie des Sciences, tome 185, page 1503 (December 19, 1927), 

 is also of interest. 



Monsieur and Madame Chauchard also proceed by measuring the 

 specific conductivity of the water in place by lowering a conductivity 

 cell inclosed in a glass cylinder to the desired depth. The glass 

 cylinder has clack valves at its upper and lower ends and contains a 

 thermometer alongside the conductivity cell. When the apparatus 

 is hauled up^after the measurement of conductivity, the clack valves 

 close, and thus the thermometer is brought up immersed in a sample 

 of water from the depth in question and the temperature at that 

 depth can be read off. 



Sir John Murray and Dr. Johan Hjort, in The Depths of the 

 Ocean (Macmillan, London, 1912), make mention of salinity meas- 



