SECT. 1] 



CHEMICAL INSTRUMENTATION 



111 



values of concentrations of one of the major dissolved constituents, usually of 

 chloride. 



Empirical relationships in the form of interpolation formulae or tables have 

 been constructed for the pairs of properties shown in Table I. The designations 

 measured and computed merely indicate the prevailing use of the relationships. 



Table I 



Measured 



Computed 



References 



1. Chlorinity 



2. Chlorinity (T and P) 



3. Chlorinity 



4. Electrical conductivity 



and temperature 



5. Refractive index (T) 



6. Chlorinity (T) 



7. Chlorinity (T) 



Salinity 



In situ density 



The concentrations of 



major and several minor 



constituents 

 Chlorinity 



Chlorinity 

 Vapor pressure 

 Osmotic pressure 



Forch, Knudsen and 



Sorensen (1902) 

 Knudsen (1901) 

 See for example, Lyman and 



Fleming (1940), Lyman 



(1959) 

 Thomas, Thompson and 



Utterbach (1934) 



Arons and Kientzler (1954) 

 Wilson and Arons (1955) 



In each case, with the exception of 3 above, chlorinity, which is a measure of 

 the total halide concentration but predominantly of the chloride (defined 

 precisely below), is related to a property of sea- water that in some way involves 

 the sum of that property contributed by all of the dissolved substances. Strictly 

 speaking, then, the applicability of these relationships to all ocean waters 

 depends upon the validity of the constancy notion in those waters. 



At the present time the data on which judgements of this kind can be based 

 are sparce. Dittmar's (1884) analyses of seventy-seven samples from the 

 1872-1876 cruise of H. M.S. Challenger are still the only "complete" analyses of 

 sea-water. Since that time composition studies have been concerned primarily 

 with the measurement of the ratio of one of the major constituents to chlorinity. 



The best that can be said at present is that the relative composition of sea- 

 water, excluding near-shore waters and shallow seas, is nearly constant. The 

 term nearly must remain ill-defined until more data are available. However, 

 Lyman (1959) showed that vertical differences between the surface and 2000 m 

 in the Pacific, with respect to alkalinity components, nitrate, calcium, phos- 

 phate and silica, could produce a variation of 0.023 % in salinity. In the Atlantic 

 the difference was 0.007 % . These differences would not appear in salinity 

 computed from chlorinity, even though the precision of modern chlorinity 

 measuring methods is of the order of 0. 001-0. 003% in computed salinity. 



B. Chlorinity-Salinity Relation 



Both chlorinity and salinity are properties of sea-water defined in terms of 

 procedures that will yield a quantitative measure of the property. 



