BROMINE IN SEA WATER. 93 



be applied to a solution of zinc bromide and chloride ob- 

 tained by reducing a precipitate of argentic bromide and 

 chloride by zinc. But more zinc will be required than for 

 the reduction of cuprous bromide and chloride. Argentic 

 nitrate will precipitate 5 grm. of chlorine from 250 c. c. of 

 sea-water, while in the precipitate obtained in the manner 

 described there are only 1| grm. For this reason, and on 

 account of the comparatively large volume of the argentic 

 chloride, it is less easy to obtain a small volume of solution 

 for titration. 



Fehling's method of partial precipitation by argentic ni- 

 trate, with its difficult settling and sweetening of the pre- 

 cipitate, and absence of a ready test for ascertaining whether 

 the bromine has been completely separated, I leave out of 

 consideration here. 



The amount of bromine in the sea water near the en- 

 trance to the Bay of San Francisco, determined in the man- 

 ner described, is 67.5 milligrams in one liter. 



