Bonningt07i Water, near Leith^ Scotland. 305 



gredients were evaporated to dryness and the residue boiled 

 four times with an adequate proportion of alcohol. [The re- 

 sidue after extraction showed no trace of iodine or bromine.] 

 The alcoholic fluid was evaporated in a retort till an ounce 

 remained, which, with the addition of a few grains of carbo- 

 nate of soda, was evaporated to dryness in a platina crucible, 

 the residue gently heated to a low red heat for the purpose of 

 destroying the organic matter, again dissolved in water and 

 filtered. The alkaline fluid thus obtained was very carefully 

 neutralized by dilute hydrochloric acid ; it held now in solution 

 the whole amount of iodine and bromine. In my account of the 

 analysis of the sea-water in the British Channel*, I described 

 my method for separating iodine from bromine and chlorine. 

 This method, though accurate, is more tedious than the me- 

 thod of Lassaigne, which was published after I had written 

 that analysis. Lassaigne recommends to precipitate the iodine 

 by chloride of palladium, and of this excellent and approved 

 test I availed myself. Protochloride of palladium was added 

 to the above fluid, which became at first turbid, but after the 

 lapse of ten hours transparent, and a black-brown precipitate 

 of protoiodide of palladium was obtained, which, when col- 

 lected upon a filter, lixiviated and dried at Sil2°F., amounted 

 to O'O^S gr., equivalent to 0*060 gr. of iodide of silver, making 

 for 16 troy ozs. of water O'OIO gr. of iodide of silver, equiva- 

 lent to 0*005 gr. of iodine. 



6. Bromine. — The fluid obtained after the separation of the 

 protoiodide of palladium was saturated with hydrosulphuric 

 acid gas to remove the excess of the palladium salt. Having 

 separated by filtration the sulphuret of palladium the fluid 

 was evaporated, the residue dissolved, the fluid filtered and 

 concentrated by evaporation ; to this solution was added a 

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

 pared thus: one part of a saturated 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 tur- 

 bidity in a saturated solution of chloride of sodium, but 

 would indicate a very minute quantity of bromine. I refer 

 for the further proceeding to my analysis of the sea-water in 

 the British Channel. By this process 0*759 gr. of bromide 

 of silver were obtained, making for 16 ozs. troy 0*126 gr., 

 equivalent to 0*053 gr. of bromine. 



7. Potassa. — 810 grs. of the fluid containing the soluble 

 ingredients were neutralized by hydrochloric acid and the 

 sulphuric acid precipitated by chloride of barium. After 

 the separation of the sulphate of barytes, the fluid was mixed 



* See the London and Edinburgh Philosophical Magazine, No. 93, 

 July 1839. 



Phil. Mag. S. 3. Vol. 26. No. 173. April 1845. Y 



