June 22, 1857.] 



WITT'S REPORT ON SEA-WATER. 



509 



in order to ascertain its real nature, or even to determine its relative 

 proportion, would have required at least a gallon instead of one or 

 two ounces of water. 



In most cases, however, the samples were sufficient to enable me 

 to determine the specific gravity, and these numbers may possess 

 some little interest, as a further confirmation of the general observa- 

 tion of the diminution of the specific gravity of sea- water as it ap- 

 proaches the mouths of rivers. 



The experiments were made after filtering oif the suspended 

 matter, so that all the samples were in the same clear state, and at 

 the same temperature of 60° F. ; and I may be allowed to mention 

 that, although the differences may appear slight, they are, in fact, 

 considerable, it being remembered that in every case about 1000 

 grains of water are used. 



The samples were numbered as they approached the coast, com- 

 mencing at the greatest distance from it, and their specific gravities 

 are contained in the subjoined Table : — 



( * ) In these cases, there being less than 1000 grains, the specific gravity even 

 could not be taken. 



Hence it appears that the specific gravity of the open sea, unaf- 

 fected by rivers, may be assumed to be about 1-02745 to 1-02785, 

 unless at these furthest points it be still reduced by the same cause. 



The following are some of the results of other observers : — MM. 

 Adolphe and Hermann Schlagintweit * give 1*0277 as the mean 

 specific gravity of the Atlantic, from the results of a series of experi- 

 ments made on a voyage from Southampton to Bombay in 1854; and 

 Rear- Admiral Philip King, e.n., f.r.s., gives a mean specific gravity 

 for the — 



Pacific, between 10° and 40° S. of 1-02648, 

 40° and 60° „ l-02613,t 



* Philosophical Transactions, January, 1855. 

 t Ibid., December, 1856. 



