Mi;. Brown on tlie Products of the Soda Manufacture. 



together. They are so contrived that the water which runs into the first 

 pan passes through the whole six in succession. In this way a very 

 saturated solution is obtained. From the last digester, the liquor is run 

 into a largo iron vessel, where it is allowed to settle. The insoluble 

 matter which remains in the pans is of no use, and is thrown away as 

 waste. It is a source of great annoyance to the manufacturer, as also 

 to the whole neighbourhood of the place where it is deposited, largo 

 quantities of sulphuretted hydrogen being evolved from it. Numerous 

 attempts have been made to recover the sulphur from it, but without 

 success. 



The following analysis of fresh soda waste was made in the same way 

 as that of the ball soda : — 

 1. Sulphuric acid. 



The waste was digested in pure muriatic acid, and after separating the 

 insoluble matter by filtration, the sulphuric acid was precipitated by 

 chloride of barium : — 



Waste. BaO S0 3 BaO S0 3 p.c. CaO S0 3 p.c. 



2800 2-10 7-500 4396 



30-95 2-20 7-108 4-166 



Average, 4*281 



2. Sulphur. 



The sulphur was oxydized by chlorate of potash and muriatic acid, 



and the sulphuric acid thus formed precipitated by chloride of barium : — 



Ba O SO 3 , Ba O S0 3 

 Waste. BaOS0 3 p.c. fromCaOS0 3 Sulphur, p.c. 



2775 gave 2756 99-315 — 7304 = 92011 12689 



3090 — 32-40 104-854 — 7304 = 97*550 13-455 



26-95 — 27-80 103*154 — 7304 = 95-850 13 220 



Average, 13182 



3. Silica and sand. 



' By dissolving the waste in strong muriatic acid, evaporating to dryness, 

 and dissolving the residue, the silica, sand, and carbon remained as 

 insoluble matter, the last of which was destroyed by ignition. The silica 

 and sand were then separated by caustic potash : — 



Waste. Si 0& Sand. Si O Sand. Si O p.c. Sand p.c. 



50-00 gave 5-513 containing 2-640 and 2873 5280 5*746 



4. Peroxide of iron. 



After separating the silica and sand, the iron was precipitated by 

 caustic ammonia. It contained a very small quantity of alumina : — 

 Waste. Fe,o s Fe a O 3 p. c. 



2000 gave, 1*10 5-500 



50*00 — 2-46 4-920 



21-40 — 1*44 6*729 



Average 5*716 



