AN ELECTRICAL CONDUCTIVITY METHOD OF MEASUR- 

 ING THE SALINITY OF SEA WATER 



The Convention for the Safety of Life at Sea, London, 1914:, be- 

 sides establishing a continuous patrol of the ice regions of the 

 North Atlantic during the ice season, recognized the value of sci- 

 entific research of the ice problem and advised a program which 

 would institute a thorough and exhaustive investigation into the 

 meteorology and oceanography of the ice regions in order to obtain 

 a greater knowledge regarding the behavior of drifting ice. This 

 led particularly to oceanographic investigation which primarily 

 consists of the determination of the two physical characters of the 

 water, the temperature and the salinity, which vary from place to 

 place, and from time to time, both horizontally and vertically. The 

 salinity character possesses an advantage over that of temperature in 

 that the former is free from the seasonal changes which occur in 

 the latter and with the approach of summer, nullifies its value to 

 a great extent. The usual method of determining salinity is that 

 of titration, a chemical method of measuring the chlorine content 

 with silver nitrate. Other known methods are : The density method 

 by either hydrostatic weighing or with the pycnometer, or liy- 

 drometer; and by the refractive indexes of samples of varying salin- 

 ities. But all of these methods ai'e of such a nature that they do 

 not conform to an accurate, practical method for shipboard, and 

 it wus soon found by the ice patrol, that an innnediate knowledge 

 of the ph3'sical properties of the water masses in the ice regions 

 was especially valuable in aiding to chart the probable movements 

 of ice. In this way warnings could be sent to those vessels found 

 on courses which were leading them toward unseen dangers. There- 

 fore, as early as 1914 work was started on the design and construction 

 of an apparatus for the determination of salinity on shi])board, 

 based on tlie electric conductivity of sea water. The history of the 

 vicissitudes and discouragements met in perfecting such a piece of 

 api):irutns, from 1914 to 1921, are told in Bulletin No. 9, Inter- 

 national Ice Observation and Ice Patrol Service, 1921, pp. 79-84. 



Taking up the thread of events, we find the apparatus at the end 

 of ice patrol, 1922, described as based on sound theory but still having 

 inherent mechanical faults which necessitated elimination before 

 wi' could possess a machine which would function satisfactorily. 



