Mi;. Soda Manuf cut 



it. The evolution of gas soon becomes very rapid, bo much so, that the 

 whole mass sppeart to 1)0 in a state of ebullition. When this cease-, 

 operation is completed, ami the fused mass is raked out of the furnace and 

 allowed to solidify. The cake thus obtained is the crude carbonate of soda. 

 Tins process consists of two sub-processes, which might be conducted in 

 separate furnaces; 1. The coal is consumed at the expense of the oxygen 

 of the sulphate ol soda, causing the formation of carbonic oxide and sul- 

 phuret of sodium. 



Na S0 3 + 4 C = Na S + 4 CO 



2. The sulphuret of sodium thus formed is decomposed by the car- 

 bonate of lime, with the formation of sulphuret of calcium and carbonate 

 of sodn. 



Na S + Ca C0 2 = Na C0 2 + Ca S 



But if this compound was digested in water, a reverse action would 

 immediately take place ; sulphuret of sodium and carbonate of lime being 

 again formed. To obviate this difficulty, a large excess of lime is used 

 in the process, nearly twice as much as would otherwise be absolutely 

 necessary. This excess of lime causes the formation of a compound 

 insoluble in water, the composition of which is 3 Ca S -f- Ca 0. This sub- 

 stance has no effect upon a solution of carbonate or caustic soda. 



Analysis of Soda Ball, or Crude Carbonate of Soda. 



An average sample was obtained by pounding a large quantity of the 

 soda ball, and from this the specimens analysed were taken. 



1. To estimate the amount of soluble and insoluble salts. 



A portion of the substance was thrown on a weighed filter and washed 

 with water at about 120" F., until a portion of the filtered liquor left no 

 residue on evaporation. ' The filter and insoluble matter were then dried 

 in a water bath and weighed : — 



Soda Ball. Insol. Matter. Sol. Matter. 



100 gave, 59-87 4013 



100 — 58-92 41-08 



100 — 59-90 40-10 



Average, 5956 40'43 



2. Sulphate of soda. 



After saturating the soda ball with pure muriatic acid, and separating 

 the insoluble matter by filtration, the sulphuric acid was precipitated by 

 chloride of barium : — 



Sodar.all. BaOS0 3 BaOS0 3 p.c. Na 0S0 3 p.c. 



•Jl.ViOgave, 850 3-466 2-147 



11000 — 130 1181 0-733 



78-30 — 0-70 D-960 0-001 



Average, 1-872 1-160 



