18 Analysis of Sea Water. 



ammoniacal precipitant for every portion of bromide of sodium 

 or potassium, an equivalent of bromide of silver and chloride of 

 sodium or potassium will be formed, and the corresponding quan- 

 tity of ammonia, which kept the chloride of silver in solution, 

 will be free and act upon the bromide of silver ; but by observ- 

 ing the before-mentioned precaution, every error of that kind 

 will be avoided. Should a fluid contain iodides and bromides 

 without chlorides, and not in too small a proportion, a very good 

 method of ascertaining their respective quantities is to precipi- 

 tate them at once with nitrate of silver, and to heat the dry pre- 

 cipitate in an atmosphere of bromine. I have found, when iodide 

 of silver is melted in an atmosphere of bromine, it is entirely 

 changed into a bromide ; and from the difference of the weight 

 between the mixture of iodide and bromide of silver, and that of 

 the whole bromide of silver, the respective quantities of iodine 

 and bromine may be ascertained. Thus the quantity of iodine 

 (or bromine) stands in proportion to the difference of the weight, 

 as the atomic weight of iodine (or bromine) is to the difl'erence 

 of their atomic weights. Hence it would only be required for 

 the quantity of iodme to multiply the given difl'erence of the 

 weight by 2.627, and for that of bromine to multiply it by 1.627. 

 Professor H. Rose, of Berlin, applies a similar method for the sep- 

 aration of iodine from chlorine. — (Poggendorfi''s Ann. 1834, No. 

 37, pp. 583, 584.) 



I may appear to have dwelt long upon this subject, but the im- 

 portance into which brine-springs have arisen on account of their 

 powerful components, iodine and bromine, has induced me to ex- 

 amine the matter closely, as it may be of consequence to the med- 

 ical profession to know the exact quantity of these valuable sub- 

 stances. 



I have briefly to add, that the quantity of chlorine in sea- water 

 was ascertained by means of nitrate of silver, deducting from it 

 that proportion of bromine which had been found according to 

 the foregoing method. The quantity of sulphuric acid was 

 found by chloride of barium, the water having previously been 

 mixed with a httle nitric acid. Another portion of the water was 

 mixed with chloride of barium without the addition of an acid, 

 when the difference of the weight between this and the former 

 precipitate gave the amount of carbonate of barytes, from which 

 the proportionate quantity of carbonic acid gas was computed j 



