THE PROPERTIES OF SEA-WATER 8i 



The spécifie beat of sea-water at 175° C. may be taken from 

 tbe following table : 



Spécifie Heat of Sea-Water. 

 Salinity (per 



mille) ... o 5 10 15 20 25 30 35 40 



Spécifie heat l'ooo 0*982 0*968 0*958 0*95 1 0*945 o'939 0*932 0*926 



The spécifie heat of sea-water is less than would be expeeted 

 from the nature and amount of the dissolved salts. 



The heat eonduetivity of sea-water bas not been determined 

 praetically, but from theoretieal considérations the following 

 table is constructed, compared with fresh water expressed as 

 2,000 (really *oo2o) : 



The Surface Tension of sea-water is of considérable 

 importance to the study of oceanography. Every liquid may 

 be regarded as bounded by a surface film which behaves like 

 a stretched membrane, and sea-water is no exception. The 

 surface tension plays a part in the formation of the smallest 

 waves, and it increases with the salinity. 



Viscosity. 



Aceording to one theory, surface eurrents due to winds are 

 helped to spread to the deeper layers by the viscosity of the 

 sea-water. The viscosity of sait water is higher than that of 

 fresh, but is considerably diminished at higher températures, 

 so much so that in tropical seas of a température of 25° C. and 

 upwards the viscosity is only half of that observed at 0° C. In 

 the deeper layers of océan waters the viscosity may be higher 

 on account of the increased pressure, but it bas not been 

 aseertained experimentally. 



A rise of i per cent, in salinity only causes an increase of 

 2 to 3 per cent, in the viscosity, and since the salinity of sea- 

 water does not vary much it follows that it is the changes of 

 température which produee changes in viscosity. 



Thèse changes in viscosity are associated with différences 



6 



