ratios to one another. Thus the measure of a single constituent may be regarded as the measure of the relative concentration of the water. The halide ions are the most abundant and most easily and accurately determined. The determination of these halides is accomplished by titration with silver nitrate using potassium chromate as the indicator. The halides are calculated as chlorides and the resulting value is known as the chlorinity. A definite relationship thus exists between the chlorinity, total concentration of dissolved salts, the major individual constituents, and the physical properties of the water. The physical properties of sea water are a function of the temperature, the pressure, and the concentration of the dissolved salt. Very accurate determinations of the specific gravity of sea water a t O°C. have been made for various concentrations of chlorinity. Knowing the density a t O°C., the density of a water a t any other temperature for a given chlorinity may then be calculated. The compressibility of water is so exceedingly small that for most practical purposes in scientific considerations corrections for compressibility are invariably disregarded. This is not so in dealing with the sea. If water were absolutely non-compressible, sea-level would be ninety feet higher than it actually is. Thus in ascertaining the density i n situ of water a t great depths, this compressibility of water must be taken into consideration. By the application of the Bjerknes circulation theorem, it is possible to calculate the resultant flow of ocean currents in relation to the bottom water from the data obtained by the titration for the halides and the temperature observations. Many persons have an idea that sea water is noth'mg more or less than a solution of common salt or sodium chloride. This is not the case, as shown by the composition of sea water given in the accompanying table. The average chemist generally expresses concentration as normality or molarity per liter of solution or as grammolecular weight per kilogram of solvent. In oceanographical chemistry, because of variations in density, the concentration is expressed as grams or milligrams oer kilogram of sea water (solution) or as millimam atoms per kilogram of sea water. In correlation with biological observations, the distribution of certain nutrient salts, which serve as fertilizers for marine plants in much the same manner as for land plants, is of marked interest to the chemist. The occurrence, distribution, and r81e of a number of elements occurring in the sea, which have received no attention or only scant consideration, offer fascinating problems for study. The biochemist is interested in
-
the absorption and utilization of the many elements bv the olants and animals and in the chemical reactions and energy changes of metabolism of the greatly varied marine life. The nature and the mechanisms of the formation of marine deposits attract the geochemist. The determination of a number of physical-chemical constants, and the regularity of their variation with the changes in concentration, temperature, add pressure, is of great importance for the interpretation of the physiology of marine organisms, and some are of marked use in the rapidly growing'scienceof meteorology. The study of the complex solution, sea water, may be instrumental in arriving a t a satisfactory theory of solutions. From the chemical enrineerina viewpoint there is interest in the possible recovery and u t h a t i o n of a great number of chemical products obtainable in the sea. One of the oldest industries is the ore~arationof sodium chloride from sea water, and among the most recent is the recovery of bromine and the preparation of a number of magnesium compounds. ~
~
Milzigrnm Alom, pn Kilo. of Sea Wnln Chlorine Sodium Sulfvr (sulfate) Magnesium
caieium
Pofasium Carbon (bicarbonate and carbonate) Bromine Boroo
535.0 454.0 27.63 52.30 10.19
9.6 2.45 0.81 0.43
( X 10,) Phw-rphorun copper
Barium Iron (varier) Iodine (varies) Silver Manganese Nitrogen (nitrite) Arsenic Zinc Hydrogen Ion Selenium
Gold
300.0 200.0 150.0 38.0 35.0 20.0 10.0 0 to 10 4.0 3.0 1.0 0.5 0.025
In this paper no attempt has been made to describe the use of the Catalyst in promoting the solution of :many biolo~cal~roblemsand the study of the everinte;esting &stril;ution of the varied animal and plant life of the sea. The vessel has been described and an attempt has been made to summarize briefly the r81e of the chemist in the study of the medium that covers approximately seventy per cent. of the surface of the world. ;
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