290 Mr. Tenxext on the Yellow Prussia te of Potash Cake. 



siatc manufacturer. It possesses considerable decolorizing power, and 

 was at one time tried by the sugar refiners ; but the result did not prove 

 satisfactory. The following analysis would lead to the belief that it might 

 be of benefit as a manure, although the experiments hitherto made have 

 not confirmed this idea. Probably the active ingredients might be 

 extracted by treatment with sulphuric acid and washing with water. 

 The black matter, when treated with an acid, effervesces, and at the 

 same time the smell of sulphohydric acid is evolved. 



1. Estimation of Volatile Matter. — 60 grains being dried at 212°, lost 

 1 1*4 grains, = 19 per cent, of water. The dry mass was then ignited, and 

 lost 21-73 grains = 36*22 of carbon. 



2. Estimation of Soluble Sulphates. — The residue was then washed with 

 water, and gave of soluble salts 7*44, or 12*40 per cent., which consisted 

 of sulphate of potash and lime. This solution was divided into two por- 

 tions : to the first, chloride of barium was added, which gave of BaO SO a 

 19*43 grains per cent. = 6*70 S0 8 . The second portion was then 

 treated with oxalate of ammonia. The precipitate of oxalate of lime, 

 after being burned, gave of carbonate of lime per cent. 5*35, = 6*75 

 CaO S0 3 . The solution filtered from the oxalate of lime, was evaporated 

 to dryness, and heated to redness, when there remained of sulphate of 

 potash 3*025 grains, = 5*04 per cent. 



3. Estimation of the Silica. — The insoluble portion in water was fused 

 with carbonate of soda. The fused mass was then dissolved in hydro- 

 chloric acid, and evaporated to dryness. Hydrochloric acid was again 

 added, the solution heated, and after standing for some time, water was 

 added ; it was then filtered, washed, dried, and ignited, and gave of 

 silica 6*45 grains, = 10*75 per cent. 



4. Estimation of Iron and Alumina. — Ammonia was added to the 

 solution filtered from the silica, which precipitated the iron and alumina. 

 This precipitate, after being washed, was dissolved in hydrochloric acid, 

 and then boiled with caustic soda, which precipitated the iron as peroxide, 

 and dissolved the alumina. On filtration, the peroxide of iron remained 

 on the filter, and when ignited, weighed 835 grains, = 13*91 per cent. 

 The solution containing the alumina was then neutralised by hydrochloric 

 acid, and the alumina precipitated by carbonate of ammonia. It weighed 

 1*40 grains, = 2*33 per cent. 



5. Estimation of PJtosplioric Acid. — 50 grains of the refuse were calcined 

 and fused with carbonate of soda. The silica being separated in the 

 usual manner, to the solution ammonia was added, which precipitated the 

 alumina, peroxide, and phosphate of iron. This prenipitate was well 

 washed, and digested in hydrochloric acid. To the solution, tartaric acid 

 was added to retain the iron in solution. An excess of ammonia was 

 then poured in, until the white precipitate which was formed had com- 

 pletely redissolved. Sulphate of magnesia was then added, and the solu- 

 tion allowed to stand for 24 hours, when a crystalline precipitate deposited, 

 which was thrown upon a filter, and washed with water containing 



