14 THE EXPLORA.TION OF THE SEA [PART I 



and this water being investigated as to its chemical composition 

 with the utmost care, is used for the standardisation of the silver 

 solutions employed in the analyses. It wdll be seen then that 

 most scrupulous care is taken that the values employed in the 

 discussion of the oceanographical problems of the North- Atlantic 

 Ocean are determined with very great accuracy : the temperature 

 is in fact determined to 1/1 0th of a degree C, and the salinity 

 with an accuracy of 0*05 in 1000 parts, the density being thus 

 capable of calculation to within 0*00004. These observations — 

 depth, temperature and salinity — are at the present time being 

 made simultaneously over the whole of the North European seas. 

 England investigates the Channel, Scotland the Northern part of 

 the North Sea and the Faeroe Channel, Ireland the western part 

 of the Irish Sea and the Atlantic Ocean to the West of Ireland, 

 Germany parts of the North Sea and the Baltic, Belgium part of 

 the North Sea, Denmark the Cattegat and Belt Seas, Holland 

 part of the North Sea, Norway the Norwegian Sea, Russia the 

 White Sea and part of the Baltic, Sweden the Skagerak and part 

 of the Baltic, and Finland the Gulf of Bothnia. The reader should 

 refer to the chart (Fig. 5) of the International Fishery Investiga- 

 tions area. The various countries make cruises once a quarter or 

 oftener and the results of the analyses of the water samples 

 collected on these cruises as well as the temperatures observed, 

 and the principal plankton organisms present in the sea at the 

 time of the cruises, are then communicated to the International 

 Fishery Council and are published and discussed by the latter^ 



These determinations of the physical and chemical nature of 

 the waters of the seas by no means exhaust the amount of infor- 

 mation that a study of the properties of that liquid can afford. 

 A knowledge of the amounts of dissolved gases such as oxygen, 

 carbonic acid, sulphuretted hydrogen, etc., is often required. So 

 also with the dissolved nitrates and nitrites and ammonia salts ; 

 the sulphates, phosphates and carbonates, the dissolved lime and 

 silicic acid. I am sure that the reader wdll excuse me from a 

 recital of the means of determination of these various constituents 

 of sea water. I need only observe here that all are required in 

 the discussion of the problems connected with the biology of 



1 In the Bulletins des Resultats. 



