216 Mr. G. W. Brown on Drift Weed Kelp from Orkney. 



Estimation of Carbonic Acid. — The carbonic acid in the soluble salts 

 was determined in the same manner as in the insoluble salts, by passing 

 the gas evolved by the muriatic acid from the solution of the salts, 

 through caustic barytes dissolved in water. The carbonic acid precipi- 

 tated the barytes as carbonate, from which the carbonic acid was calcu- 

 lated. 



Carbonate of Barytes. Carbonic Acid. Carbonic Acid, per cent 



500 grains gave 48-62 10-9 2-180 



Estimation of Chlorine. — A solution of the soluble salts was boiled 

 with nitric acid, to convert the sulphurets into sulphates ; the chlorine 

 was then precipitated by nitrate of silver. 



Chloride of Silver. Chlorine. Chlorine, per cent 



15 grains gave 14-1 3-52 23-40 



— — 15-5 3-88 25-33 



Mean, 24-365 



Estimation of Iodine. — This, which is one of the most valuable con- 

 stituents of kelp, was determined by the following method, which has 

 yielded results very satisfactory. 



A portion of the kelp was exhausted of its iodide, by digestion several 

 times in alcohol. The alcoholic solution was then evaporated to dryness, 

 and, to convert any sulphuret which might have been taken up by alcohol 

 into sulphate, was deflagrated with chlorate of potash, and kept at a red 

 heat till any iodate that might have been formed by the action of the 

 chlorate of potash, was decomposed. The mass was then dissolved in 

 water, and the iodine precipitated, by means of chloride of palladium, as 

 iodide of palladium, which was dried at 212° F., and weighed — 



Iodide of Palladium. Iodine. Iodine, per cent. 



1000 grains gave 4-05 2-83 -283 



— — 4-35 306 -306 



500 — 2-05 1-437 -287 



Mean Iodine, per Cent, -292 



Separaiion of Bromine and Iodine. — To eflfect the separation of the 

 iodine and bromine, a pound of kelp was ti-eated with alcohol which 

 dissolved out the bromide and iodide. The alcohol was then driven 

 off. Through the aqueous solution of the salts, chlorine was passed in 

 order to decompose the iodide and bromide, the iodine and bromine being 

 set free. This liquor holding in solution free iodine and bromine, was 

 frequently agitated with ether in a stoppered bottle. The aqueous 

 solution gradually became clear on standing, and the ether, containing the 

 bromine and iodine, floated on the surface. This ethereal solution was 

 then decanted and saturated with soda, after which it was evaporated 

 to dryness and heated to redness, to destroy any iodate or biomate. The 

 residual salts were dissolved in water, and the iodine precipitated by 



