300 CONCERNING THE EFFECT OF GRAVITY DAVIS. 



Superposed on this is the effect of gravity, which, as we have 

 seen, will, for inorganic salts, be to increase the concentration 

 with the depth. I have roughly represented the first effect by 

 the curve (1), Fig. 4, and that of the second by curve (2). They 

 will give a resultant curve (3) of change in concentration with 

 depth, and if we suppose the first effect to be the greater near 

 the surface, then the concentration will first decrease, not neces- 

 sarily uniformly, down to a certain point where the two effects 

 just counterbalance, and from thence will increase steadily to 

 the bottom. 



This would account for the actual distribution of the saline 

 contents of sea water as actually found from the summary of 

 the researches on the "Challenger" as given by Dittmar. (See 

 Encyclopaedia Britannica, 9th edit., "Sea Water"). 



"In places where there is active dilution at the surface, the 

 salinity as a rule increases down to some 50 or 100 fathoms, 

 but thence downward it follows the general rule, that is, it 

 decreases down to 800 or 1,000 fathoms, and thence increases 

 steadily to the bottom/' 



Of the data available from the reports on the concentration 

 of the separate constituents, only that of the absorbed gases is 

 of value since the others were determined relatively to the total 

 chlorine content. 



Apart from the fact of the large increase of solubility of 

 gases with temperature, the increase of density with concentra- 

 tion, though positive, is extremely small and difficult to measure. 

 (S e Ostwald, Solutions, p. 32). 



Tt was found that: 



(1) The amount of nitrogen increases with the depth. 



(2) The amount of oxygen decreases with the depth. 



But as a matter of fact, the increase of density with con- 

 centration for oxygen is greater than for nitrogen, which ought 

 therefore to show a greater increase with the depth. 



Dittmar explains the decrease of oxygen as being due to 

 oxidation. 



(For the greater part of the mathematics in this paper I am 

 indebted to Dr. H. L. Bronson, of the Department of Physics, 

 Dalhousie College.) 



