78 Papers from the Marine Biological Laboratory at Tortugas. 



place of the directly determined density in computation of the chemical 

 analysis. Obviously, however, the relation could not be depended upon 

 for inland saline solutions, which vary greatly in the percentage composition 

 of their anhydrous residues. 



DIFFERENCE IN CONCENTRATION. 



The salinities of the three samples taken outside the reefs (2, 3, and 4) 

 agree closely with each other and with the salinity of gulf water at Tortugas, 

 Florida (36.01), which is somewhat greater than that of standard ocean 

 water (35.02). The water in the south part of the bay is somewhat more 

 concentrated, samples Nos. 9, 5, and 8 having salinities of 36.73, 36.64, and 

 36.64, respectively. This evidence that the water in this part of the bay 

 is concentrated by evaporation during its retention in the shallows serves 

 further to indicate that circulation there is not very rapid and that the 

 greater bulk of the water inside the keys is not thoroughly mixed or shifted 

 by the tides. The inside samples only as far south as Old Man Beacon 

 give evidence of dilution by fresh water; therefore it may be concluded 

 that, at least at the time these samples were collected, the effect of Miami 

 River on the water of the bay did not extend south of Soldier Key nor 

 outside the keys. Sample i has a salinity obviously higher than the pure 

 water of Miami River alone may be expected to have, and represents 

 admixture with bay water ; carbonates are absent from it, but bicarbonates 

 are much higher than in the normal drainage from the Everglades and may 

 be attributed to reaction of the carbon dioxide that the river water carries. 

 In all other samples normal carbonates are present as in sea-water and 

 free carbon dioxide is entirely absent, but there are wide differences in the 

 alkalinity from point to point. 



