56 Dr. G. Schweitzer's Analysis of Sea-'waier as it exists 



was again treated witii a:tlier, lest any bromine should still 

 remain in it. The aether was directly introduced into a glass 

 bottle, containing a solution of caustic potash lully sufficient 

 to discolour the aether, when after evaporation and ignition 'it 

 was dissolved in water, and carefully neutralised with hydro- 

 chloric acid. The concentrated solution was mixed with a 

 few drops of an ammoniacal solution of chloride of silver pre- 

 pared thus : one part of a concentrated solution of chloride of 

 silver in ammonia, mixed with one part of ammonia and one 

 part of water. A few drops of this mixture produced no 

 turbidness in a solution of chloride of sodium, but indicated a 

 very miimte quantity of bromine. When no further turbid- 

 ness was produced by an additional drop of this ammoniacal 

 solution of the chloride of silver, die fluid under treatment, 

 which was kept in an open vessel, was heated in a sand-bath 

 until the ammonia was almost evaporated. A few drops of 

 the test were again added, until it no longer produced turbid- 

 ness, when the glass vessel was again placed in a sand-bath, 

 until the fluid, after having been heated, gave no further indi- 

 cation of bromine ; it was then tested again with chlorine. 

 When the proportion of the chlorides to the bromides is not 

 too large, scarcely a faint yellowness will be produced ; if, 

 however, it is, the bromine must again be separated by chlo- 

 rine and asther, and the before-mentioned process repeated, 

 when the last traces of bromine will be separated as bromide 

 of silver, which is to be treated like the iodide of silver before 

 it is weighed. In this manner I have been able to detect the 

 smallest proportion of an iodide and bromide when accom- 

 panied by a great quantity of chlorides, and have also been 

 enabled to separate them and to ascertain their respective 

 quantities. Should the quantity of iodine be much larger 

 than that of bromine, it would be requisite to evaporate a 

 little of the ammonia ; and although the addition of the ammo- 

 niacal solution of chloride of silver, employed as a test for 

 iodine, no longer produces turbidness, it is still necessary to 

 add another drop of the precipitating fluid, in order to ensure 

 the separation of every trace of iodine. This is the more 

 important, as the iodide of silver is not entirely insoluble in 

 ammonia ; and although the quantity dissolved might be ex- 

 ceedingly minute, still this repetition is necessary in an accurate 

 analysis. The same precaution must be observed in the 

 separation of bromine, as bromide of silver is to some extent 

 soluble in ammonia, for it is obvious that by the addition of 

 the 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 



