16 Anal'i/sis of Sea Water. 



silver to subside. It is well when bromides are present to keep 

 the vessel closed during the process, otherwise it is of no impor- 

 tance. The iodide of silver collected upon a small filter was 

 first washed with a little diluted ammonia, and afterwards with 

 a few drops of diluted hydrochloric acid to dissolve any earthy 

 substance which the precipitate might contain, and ultimately 

 with pure water. 



The filter with the precipitate was dried and ignited. This 

 experiment, repeatedly performed, yielded the most satisfactory 

 results. It requires time, but this is more than balanced by its 

 accuracy. Thus, for instance, I obtained by the analysis of the 

 Congress spring of Saratoga, from 100,000 grs. of the water, 

 0-12164 gr. of iodide of silver, representing in 1000 grs. of the 

 mineral water, 0-00067 gr. of iodine. 



The ammoniacal fluid, separated from the iodide of silver, was 

 carefully evaporated to expel the ammonia, whereby a small pre- 

 cipitate was obtained, consisting of bromide of silver, which was 

 added to that subsequently obtained. This precipitate was form- 

 ed by the solution of the chloride of silver, more of which was 

 added than was required for the separation of the iodine. That 

 this minute precipitate consisted of bromide of silver, was 

 proved by heating it in a test tube with concentrated sulphuric 

 acid, whereby it became of a delicate yellow color ; whereas 

 chloride of silver would have remained white, and iodide of sil- 

 ver would have obtained a brown color by parting with its 

 iodine. 



A small portion of the fluid may now be examined for bro- 

 mine, and, when present, the following process may be adopted, 

 which is the same I employed for the separation of bromine in 

 sea-water and brine-springs, where the quantity of chlorides is 

 comparatively very large. The concentrated solution freed from 

 the iodine was introduced into a glass ball, having at its lower 

 end a glass tube, and at its upper an aperture closed by a glass 

 stopper. A concentrated aqueous solution of chlorine was added 

 as long as any sensible yellowness was caused by its addition. 

 The fluid was then agitated with pure ether ; and after this had 

 collected on the surface, carrying with it the bromine and chlo- 

 rine, the water was allowed to flow off through the tube below, 

 and by careful manipulation the ether could then be freed from 

 the water, which was again treated with ether, lest any bromine 



