110 CARRITT [CHAP. 5 



The instrumentation connected with chemical measurements made in a 

 shore-based laboratory presents very few problems that are uniquely oceano- 

 graphic. Once a sample (water, sediment or bio-material) is ashore the problems 

 of analysis can be approached with the full compliment of analytical tools and 

 techniques that are available for all analysis problems. It is sufficient to note 

 here that during recent years there has been a much greater utilization of 

 current analytical instrumentation than was obvious in the past. Significant 

 oceanographic results have come from a wide variety of applications of mass 

 spectrometers, X-ray techniques, neutron activation, ultraviolet, visible and 

 infrared absorption measurement, and radioactive tracer uses, to name only 

 a few. 



As in 1952 and previous years, much recent effort has been toward improving 

 chlorinity measurements. Present instrumentation provides an apparent 

 improvement in precision in routine measurements of nearly an order of 

 magnitude. The overall result of this improvement is not fully understood 

 because the accuracy of the empirical relation between the property actually 

 measured, conductivity, and the property sought, chlorinity, leaves an un- 

 certainty in computed chlorinity at least an order of magnitude greater than 

 implied by the precision of the conductivity measurements. Nevertheless, the 

 development of inductive conductivity devices suggests that the instrumenta- 

 tion of routine, in situ measurements of electrical conductivity of high accuracy 

 and precision is now possible. 



2. Chlorinity, Salinity, Density and Related Properties 



A. Introduction 



Much of what we know about the oceans, or more precisely, what we think 

 we know about them, depends upon a belief in what has been variously called 

 Maury's Principle, Dittmar's Hypothesis, Forchhammer's Hypothesis and, 

 more recently, attributed to one of several other workers who studied or 

 speculated on the chemical composition of sea-water. This hypothesis sets forth 

 the notion that, so far as the major dissolved constituents are concerned, sea- 

 water has constant relative composition. This is, considering sea-water to be an 

 aqueous solution of some eleven inorganic constituents (see, for example, 

 Lyman and Fleming, 1940, table III, p. 137), the only difference that can be 

 found between samples is in the water content. It follows, then, that the ratios 

 of the concentration of any one of these constituents to any other, or to any 

 combination of others, will be constant in all samples of sea-water. 



The importance of the notion of constancy of relative proportions to parts of 

 oceanography, other than merely as a descriptive feature of the chemical com- 

 position of sea-water, is evident from an examination of the empirical relation- 

 ships that have been obtained. By these relationships a variety of physical and 

 chemical properties of sea-water are said to be predictable from measured 



