The average salinity of the whole surface of the oceans may be taken as 34.5 per mille.
The comparatively fresh equatorial belt of water, has a salinity of 35.
The salinity of enclosed seas naturally varies much more than that of the open ocean.
the Baltic Sea and Hudson Bay with very low salinity, the Red Sea and Persian Gulf with very high salinity.
a temperature of 40.1 ° F., the carbonic acid amounts to 51 J5 cc. per litre, and the oxygen only to 2.19 cc. Vegetable plankton in sunlight can reverse this process, assimilating the carbon of the carbonic acid and restoring the oxygen to solution, as was proved by Martin Knudsen and Ostenfeld in the case of diatoms. Little is known as yet of the distribution of carbonic acid in the oceans, but the amount present seems to increase with the salinity as shown by the four observations quoted: Water from Gulf of Finland of 3.2 per mille salinity =17.2 cc. C02 Western Baltic of 14.2 North Atlantic of .0, , 49'0 Eastern Mediter ranean of 39.o, , =53'0, , Unfortunately the very numerous determinations of carbonic acid made by J.