and Fleming (19^2) as the number giving the chlorinity in grams per kilo- 

 gram of seawater sample and is equal to the number giving the mass in 

 grams of "atomic weight silver" just necessary to precipitate the holo- 

 gens in 0.3285233 kilograms of the seawater sample. The chlorinity of 

 seawater ranges from about l8 to 20 parts per thousand, averaging about 

 19 parts per thousand. The term salinity is intended to denote the total 

 amount of dissolved salt in seawater. For convenience, salinity is 

 usually calculated from the chlorinity of seawater using the formula: 



Salinity = 0.03 + 1.805 X chlorinity 



The salinity of seawater ranges from approximately 33 to 37 parts per 

 thousand and the average in the open sea is of the order of 35 parts per 

 thousand (Shreir, 1963). 



3. Temperature 



Seawater surface temperatures, in general, range from -2° to 

 3 5 °C -(approximately 28° to 95° F). Its freezing point is -2° C. 

 Fluctuations in the temperature of seawater at a given location decreases 

 with depth (Baxter, et al, 1960). 



k. Electrolytic Qualities 



Electrolytes are substances containing tiny charged particles 

 called ions. Electrolytes conduct electric current by the flow of ions. 

 Seawater contains ions as a result of the dissolved salts. The analysis . 

 of a sample of water from the North Pacific Ocean (Fink, I960) revealed 

 the presence of various cations (positively charged ions) and anions 

 (negatively charged ions) as shown below: 



Ions in North Pacific Seawater Samples 



Cations 



Percent 



Na-^ 



1.056 



Mg-^^ 



0.12T 



CA"^^ 



O.Oi+0 



K^ 



0.038 



Sr-^^ 



0.001 



Sum: 



1.262 



Anions 





Percent 



Cl" 





1.898 



soi; 





0.265 



HCO3 





O.OII+ 



Br~ 





0.0065 



f" 





0.0001 





Sum: 



2.1836 



lissoci; 



ated) 



0.003 



Grand Total 3. ^^9 percent 



The ions contained in seawater are a necessity in carrying out the electro- 

 chemical process of corrosion. Further details on the part played by ions 

 in the corrosion of steel piling are given in Section IV. 



