324 Dwellers of the Sea and Shore 



Of all the elements, sodium chloride, or common salt, 

 exists in the largest amount; this heing present in the 

 proportion of 27.2 13 per 1,000 parts of water. Other 

 salts exist also, though in minor quantities ; still they are 

 sufficiently voluminous to Impart a distinctly bitter 

 taste; and they, together with the sodium chloride, 

 make the water unsuitable for drinking or domestic 

 purposes. 



The specific gravity of sea water Is correlated with 

 Its salinity, or saltiness. This Is merely to say that salt 

 water is more buoyant than is fresh water; objects will 

 not sink so readily In the sea as they will In fresh 

 water. But the comparatively greater buoyancy of the 

 sea Is not so marked as Is generally believed. It Is so 

 slight, in fact, as to be ordinarily Imperceptible; assur- 

 edly, the difference Is not great enough to be detected 

 by the bather, as has been frequently maintained. The 

 specific gravity of pure fresh water at a temperature of 

 39.2° Fahr. Is i, the standard unit to which the spe- 

 cific gravities of all liquids and solids are referred. 

 The specific gravity of the sea, out of reach of such 

 exceptional Influences as those of the melting snow, 

 rain, or river water. Is 1.02655 at a temperature of 

 62° Fahr. Slight variations In the saltness of the 

 ocean occur In different localities, and these necessarily 

 produce corresponding changes In Its specific gravity. 

 On the north and south limits of the torrid zone the 

 mean specific gravity appears to be less than that of the 

 equatorial calm belt; and it shows a tendency to dimin- 

 ish as the latitude Increases. 



Where the sea Is not affected by currents from 

 warmer or colder regions. Its temperature corresponds 



