ATMOSPHERIC GASES IN SEA-WATER 95 



CO 2 for the same water. Fox's recent work is based on the 

 fact that the success in extricating gases dissolved in waters 

 depends very largely on the maintenance of the evacuated 

 space ; the gases must be pumped away continually from the 

 surface of the liquid as soon as evolved. 



The alkalinity of sea-water varies, increasing in the 

 neighbourhood of alkaline bottom sediments and where there 

 is an appreciable mixture of land water, decreasing where 

 there is a utilisation of carbonates by marine organisms. 

 Certain marine sediments contain calcium and magnesium 

 carbonates, and when there is an excess of free CO 2 these 

 are dissolved, rendering the sea-water more alkaline. Water 

 derived from the land might be expected to reduce the 

 alkalinity of sea-water by dilution. But land water itself, 

 especially "hard" water, is alkaline. An increase in 

 alkalinity, though slight, has been determined off the west 

 coast of Greenland, and this is attributed to the influence of 

 water derived from the land. In Gullmar Fiord, Sweden, the 

 water near the surface should have, according to the salinity, 

 an alkalinity of i8'97 ; the alkalinity actually determined was 

 2276. At 55 fathoms the alkalinity calculated from salinity 

 (26'38) and that determined by analysis (26*37) approximate 

 very closely. In the surface waters the difference is attributable 

 to the influence of land water. Observations made in the 

 Baltic under the auspices of the International Council also 

 show how strong the influence of land water is in increasing 

 alkalinity. 



A decrease due to the activity of marine organisms is 

 probably of no great significance. Sir John Murray estimated 

 that one square mile of sea-water to a depth of 100 fathoms 

 contains in the bodies of planktonic organisms 16 tons of 

 calcium carbonate. Reduced to 1,000 c.c. (i litre), the 

 amount of carbonate of calcium is only 0^0255 milligram, 

 which w 7 ould give an alkalinity of o'Oi milligram. The 

 amount of calcium carbonate in the skeletons and shells of 

 marine planktonic organisms must be renewed twenty times 



