Drift-Weed Kelp from Orkney. 259 



Estimation of Hyposulphurous Acid. — The soluble salts 

 being separated by means of cold water from the insoluble 

 salts, the sulphurets and carbonates were removed by sul- 

 phate of copper. After separating this precipitate by filtra- 

 tion, sulphuric acid was added to the liquid, which decomposed 

 the hyposulphites, sulphurous acid being evolved, and sul- 

 phur precipitated. This sulphur was then washed, dried at 

 212° Fahr., and weighed, roitfblws GI ft .ggonboi o* boteed neod 

 jfefitoq 3 o 9 Dfi js beonb 



a . , Hyposulphurous Hyposulphurous 



Sulphur.; }<) -Acid. Acid, per cent. 



to^ 400 grains gave '18 = 54 -135 



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Estimation of Sulphur. — The quantity of sulphur in the 

 soluble salts was estimated by deflagrating a portion of the 

 kelp with nitre. By this process all the sulphites, hyposul- 

 phites, and sulphurets were converted into sulphates. The 

 sulphuric acid was then precipitated by chloride of barium, 

 as sulphate of barytes, which was weighed, and the sulphuric 

 acid contained in it calculated. It is obvious that the sul- 

 phuric acid thus obtained comprehended all the sulphur exist- 

 ing as sulphurets, and sulphur acids in the original kelps. 

 If we subtract from it the sulphuric acid found to exist as 

 such in the kelp, we have remaining the sulphuric acid 

 equivalent to the sulphites, hyposulphites, and sulphurets in 

 the kelp. If, again, we subtract from the last result the 

 calculated quantity of sulphuric acid, equivalent to the sul- 

 phurous-hyposulphurous acid, and the sulphuret of the 

 insoluble salts, the remainder will be the sulphuric acid, 

 equivalent to the sulphur of the soluble salts. 



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Sulphate of Sulphuric Sulphuric Acid, 



Barytes. Acid. per cent. 



200 grains gave 46-55 16-04 8-02 



Original sulphuric acid, 4-920 



Sulphuric acid =" Sulphurous acid, -490 3-10 

 = Hyposulphurous acid, -191 

 Sulphur, insol. salts, '965 



Total calculated sulphuric acid, 1*446 



Sulphuric acid = Sulphur of sol. salts, 1*654 

 Sulphur, soluble salts, per cent., -6616 



