SECT. 1] 



PHYSICAL PROPERTIES OF SEA-WATER 



21 



is nearly constant and provides an easy method for comparing various results 

 reported in the literature. In the formula given by Sverdrup (1942) and the 

 table by Miyake (1952), the ratio is constant. More recent measurements by 

 Robinson (1954) and Arons and Kientzler (1954) indicate that the ratio in- 

 creases slightly with salinity. A comparison of the ratios obtained by these 



6.0 



xlO 



r/S 



5.0 



4.0 



Miyake (1952) 



Sverdrup (1942) 



Robinson (1954) 



Arons and Klenfzler (1954) 



10 



20 



30 



S %. 40 



Fig. 6. Variation of the ratio r/S with salinity, S, where r is the fractional lowering of 

 vapour pressure of sea-water as compared with pure water. 



10 



20 



30 



40 



Fig. 7. Variation of the ratio 7-/S with temperature, where r is the fractional lowering of 

 vapour pressure of sea-water as compared with pure water, and S is salinity. The 

 points are based on the determinations of Arons and Kientzler (1954). 



authors is given in Fig. 6. Miyake's (1952) table gives the greatest lowering of 

 vapour pressure; about 10% greater than obtained by Arons and Kientzler 

 (1954). The temperature dependence of rjS is small, as may be seen from Fig. 7. 

 Measurements of freezing-point depression (Knudsen, 1903; Miyake, 1939) 

 and boiling-point elevation (Miyake, 1939) are too restricted in temperature 

 range to provide an adequate definition oi s dfi/ds. Further determinations of 



