The Nature of Sea Water 33 
pretty well known. The accompanying table gives the per- 
centage of different chemical elements present in a typical 
sample of sea water. We do not include the hydrogen and 
oxygen that make up the water itself. As you will see, sodium 
and chlorine make up the largest portion of the impurities in 
sea water. Together they form sodium chloride—ordinary 
salt—but there are smaller quantities of other elements which 
are combined to form many complex substances and ions. 
TABLE OF ELEMENTS IN SEA WATER 
(dissolved gases excluded ) 
Chlorine 1.898% Strontium 0.0013 Phosphorus 0.00001 max. 
Sodium 1.056 Boron 0.00046 Barium 0.000005 
Magnesium 0.127 Silicon 0.00040 max. Iodine 0.000005 
Sulphur 0.088 Fluorine 0.00014 Arsenic 0.000002 max. 
Calcium 0.040 Nitrogen 0.00007 max. Iron 0.000002 max. 
Potassium 0.088 Aluminum 0.00005 Manganese 0.000001 max. 
Bromine 0.0065 Rubidium 0.00002 Copper 0.000001 max. 
Carbon 0.0028 Lithium 0.00001 
plus the following: . 
0.0000005% to 0.00000005% zinc, lead, selenium, cesium, uranium, molyb- 
denum. 
0.00000004% to 0.000000003% thorium, cerium, silver, vanadium, lantha- 
num, yttrium, nickel, scandium, mercury. 
0.0000000006% gold. 
0.000000000000003% radium. 
plus tiny traces of cadmium, chromium, cobalt and tin. 
In practical oceanography many analyses are made of 
ocean water, but few are made in such a detailed form as 
given above. Instead, a crude kind of determination is usually 
made by mixing a sample of sea water with standard silver 
nitrate solution, using potassium chromate as an indicator. 
The silver solution is poured into a sample of sea water by 
means of a burette (measuring tube). When the solution first 
