64 



The Sea-water and its Physical and Chemical Properties 



Turbidity 

 discoloured 



70ny/F60. 

 ;-5l5m/^F25. 



|i-488ny/F5. 



477ny/ FO. 



Magnitude of porticipotion 

 of the individuol factors 

 giving rise to ttie colour of 

 the sea 



Fig. 36. Quantitative representation of the contribution of the individual factors giving rise 

 to the colour of the sea (according to Kalle). 



8. The Chemistry of the Sea 



In general, liquids have the property of absorbing gases with which they are in 

 contact to give a solution of the gas in the liquid. The solubility of the gas in the liquid 

 is not unlimited, but usually fairly soon reaches a limit; the liquid is then saturated. 

 According to Henry's law the amount of gas dissolved in a saturated solution is pro- 

 portional to the pressure of the gas in contact with the liquid. If the liquid is in contact 

 with a mixture of gases then each separate gas is absorbed according to its partial 

 pressure. When the liquid is completely at rest the process of solution depends on the 

 process of diffusion, and thus requires time for the pressure of the gas in the liquid 

 to come to the same pressure as the gas outside it. In nature, the wave motions, 

 turbulent currents and convections can accelerate considerably the uptake of gas by 

 the liquid. By the gas content of a sample of water is understood the amount of gas 

 in the water expressed in volume units (ml/litre) at NTP (0°C and standard pressure 

 of 760 mm Hg). The actual gas content may of course differ more or less from the 

 amount present when saturated. 



Besides, by this absolute definition the gas content may also be characterized by the 

 ratio of actual content to that by saturation. It is then specified by the relative gas 

 content which is expressed in per cent of the amount required for saturation. The 

 absorption coefficient is taken as that volume of gas which can be absorbed by unit 

 volume of liquid at a given temperature and standard pressure. 



