J) rift- Weed Kelp from Orkney. 261 



1000 grains gave 4-05 2-83 -283 



1000 ... 4-35 3-06 -306 



500 ... 2-05 1-437 -287 





Mean iodine, per cent., *292 



Separation of Bromine and Iodine. — To effect the separa- 

 tion of the iodine and bromine, a pound of kelp was treated 

 with alcohol, which dissolved out the bromide and iodide. 

 The alcohol was then driven off through the aqueous solu- 

 tion of the salts. Chlorine was passed in order to decompose 

 the iodide and bromide, the iodine and bromine being set free. 

 This liquor, holding solution of free iodine and bromine, was 

 frequently agitated with ether in a stoppered bottle. The 

 aqueous solution gradually became clear on standing, and 

 ether containing the bromine and iodine floated on the sur- 

 face. This ethereal solution was then decanted, and satu- 

 rated with soda, after which it was evaporated to dryness, 

 and heated to redness, to destroy any iodate or bromate. 

 The residual salts were dissolved in water, and the iodine 

 precipitated by chloride of palladium. The iodide of palladium 

 being separated by filtration, the excess of palladium was 

 removed from the filtrate by sulphohydrate of ammonia. It 

 was found in this experiment that sulphohydrate of ammonia 

 answered better than sulphohydric acid for removing the 

 excess of palladium ; because when sulphohydric acid is em- 

 ployed, part of the sulphuret of palladium is dissolved by the 

 acid which was previously united to the palladium, which 

 was set free by the sulphohydric acid. Having removed the 

 excess of sulphohydrate of ammonia by boiling, chlorine was 

 again passed through the solution, to decompose bromide. 

 The bromine which was set free was taken up by ether (this 

 had a yellow colour, probably from the presence of a small 

 quantity of bromine). The ethereal solution was then neu- 

 tralised by soda, evaporated to dryness, and heated to redness. 

 The aqueous solution of the residue gave a white precipitate 

 with nitrate of silver, which consisted principally of chloride 

 of silver. But from the colour of the ether, it was evident 

 that it contained a small quantity of bromine. 



