Mr. J. Brown o?i the Products of the Soda Manufacture. 29 



12. Bisulphuret of calcium. — A quantity of the waste was 

 digested with muriatic acid and a large quantity of water, and 

 heated till the whole of the sulphuretted hydrogen was dissi- 

 pated. The sulphur which remained was then oxidized by 

 chlorate of potash and muriatic acid, and the sulphuric acid 

 thus formed precipitated by chloride of barium. But as this 

 method does not yield very accurate results, the amount of 

 bisulphuret of calcium given below can only be considered as 

 an approximation. 



Waste. BaO, SO3. Sulphur. Sulphur per cent. CaSj per cent. 



35-8 gave 11-45 1-579 2-205 3'583 



13. Hyposulphite of lime. — About 100 grains of the waste 

 were digested for twenty-four hours with a solution of oxalate 

 of potash ; a salt of the oxide of copper was then added, by 

 which all the sulphur was thrown down. The precipitated 

 sulphuret of copper was then separated by filtration, and to 

 the filtered solution sulphuric acid was added. At first no 

 precipitation took place; but after standing for one or two 

 hours, the solution became slightly turbid. The quantity of 

 sulphur was, however, too small for estimation. 



14. Water. 



Waste. Water per cent. 



100 grains lost by drying at 212° 2*10 



Soluble salts . . 26-264. 

 Insoluble salts . 73*736 



100-000 



Sulphate of lime ...... 4-281 



Sulphur 13-182 



Silica 5-280 



Sand 5-746 



Peroxide of iron 5-716 



Lime 44-762 



Magnesia 0-707 



Carbonic acid 11-190 



Carbon 12-078 



Carbonic acid in insoluble salts . 10-657 



Lime in insoluble salts . . . 30*448 



Bisulphuret of calcium . . . 3-583 



Hyposulphite of lime .... trace 



Water 2-10 



