214 Mr. G. W. Bkowx on Drift Weed Kelp from Orkney. 



The oxygen was obtained by calculating the quantity necessary to 

 form water, which, being united to the nitrogen, would not be driven off 

 at 212° F. 



Analysis of Soluble Silts. 

 Teding Analysis of Soluble Salts.— Those^ salts which were soluble in 

 water were, before proceeding to the quantitative analysis, tested qualita- 

 tively. The following are the results : — On addition of muriatic acid to 

 the solution of salts, an effervescence took place, with evolution of carbonic 

 acid and sulphuretted hydrogen. Sulphuric acid produced a dark colour 

 in the solution, from the liberation of iodine. This, however, disappeared 

 on heating the liquid, fumes of iodine being evolved. After precipitating 

 the sulphurets by sulphate of copper, the addition of a small quantity of 

 sulphuric acid made the liquid slightly turbid from the precipitation of 

 sulphur, proving the presence of a small quantity of hyposulphurous acid. 

 When nitrate of silver was added to a solution of the salts, a black 

 precipitate fell from the formation of sulphuret of silver; but after a 

 portion of the salts had been boiled with nitric acid, the precipitate with 

 nitrate of silver was white and curdy, indicating the presence of chlorine. 

 Chloride of barium gave a white precipitate, part of which being dissolved 

 with effervescence in nitric acid, indicated the presence of carbonic acid. 

 A white powder remained unacted on by the nitric acid, showing that the 

 salts contained sulphuric acid. After a portion of the salts had been 

 heated to redness, the addition of bichloride of platinum produced a 

 yellow precipitate, proving the existence of potash salts in the kelp. 

 Oxalate of ammonia caused a slight precipitate of lime ; and phosphate of 

 Boda and ammonia, after some time, a precipitate of ammonia phosphate 

 of magnesia. 



Quantitative Analysis of Soluble Salts. 



Estimation of Sulphuiic Acid. — Having separated, by filtration, a 

 portion of the soluble from the insoluble salts, the sulphuric acid was 

 precipitated in the soluble salts by the addition of chloride of barium 

 and muriatic acid, to dissolve sulphites and phosphates. 



Sulphate of Barytes. Sulphuric Acid, per cciit. 



100 grains gave 14-21 ... 4-89 



100 " " 14-34 ... 4-94 



Mean per centage, 4-915 



Estimation of Suljyhurous Acid. — To a solution of the soluble salts 

 chloride of barium was added, which precipitated the sulphuric, sulphur- 

 ous, carbonic, and phosphoric acids, as salts of barytes. This precipitate 

 was thrown on a filter and washed with hot water. The sulphate, sul- 

 phite, and carbonate of baiytcs which were on the filter, were then 

 treated with nitric acid, which converted the sulphite into sulphate, and 

 dissolved the carbonate. The sulphate of baiyfos was then washed with 



