34 On the Depth and Saltness of the Ocean. 



" The quantity of soda and sodium was found by subtract- 

 ing the sum of the weights of the other ingredients from the 

 whole weights of the dry salts obtained by the first evapora- 

 tion. Four or five specimens of water were examined for 

 iodine, bromine, and potash, of which no traces were found. 



" The filtering paper used was the fine white unsized India 

 paper. Equal double filters were used throughout, burned 

 separately in platina crucibles over the spirit-lamp, and 

 weighed against each other ; for the greater part of the salts 

 the filters were counterpoised previous to filtering. 



" The water used was distilled in Bohemian glass retorts, 

 and was absolutely pure. All the tests and re-agents were 

 prepared in Di' Jackson's laboratory, and were proved to be 

 pure before employing them in analysis. The balance used 

 in taking specific gravities, and for weighing the products of 

 analysis, was made by Chemin of Paris, Fr,, and is sensible 

 to the TUoth of a grain." All the tables comprising the ana- 

 lysis of the waters will be given in the volumes of the Expe- 

 dition, the two following will shew the ingredients of sea- 

 water as determined by the above method by Dr Jackson. 

 Analysis of water from the depth of 100 fathoms, in lat. 

 63° 18', S. long. 55° W. : — temperature at surface 31°, below 

 30°. March 4, 1839. Specific gravity of the water = 1-02G ; 

 temperature CO" ; bar. 3005. 



A quantity of water equal in bulk to 1000 grains of dis- 

 tilled water evaporated, gave — 



Water from the depth of 450 fathoms : — temperature at 

 that depth 44° 5' ; temperature of surface 74° ; lat. 17° 54' S., 

 Ion. 112° 53' ^Y., July 29, 1839. Specific gravity = 10275 ; 



