280 Mr. Brown on the Products of the Soda Manufacture. 



I. n. 



Carbonate of soda, 84-002 83*761 



Hydrate of soda, 1*060 0*734 



Sulphate of soda, 8*560 9*495 



Sulphite of soda, trace 0*386 



Chloride of sodium, 3*222 3*287 



Aluminate of soda, 1013 0*620 



Silicate of soda, 0*984 0*780 



Insoluble matter, 0*716 0*846 



99*557 99-909 



A finer kind of soda ash is frequently made from this salt by dissolving 

 it in water, evaporating to dryness, and carbonating. It contains very 

 little caustic soda, and should average about 50 per cent, of alkali. It 

 yielded, on analysis, — 



I. n. 



Carbonate of soda, 84*314 84*721 



Hydrate of soda, trace 0*280 



Sulphate of soda, 10*260 9*764 



Sulphite of soda, trace — 



Chloride of sodium, 3*480 3*140 



Aluminate of soda, 0*632 0*716 



Silicate of soda, 0*414 0*318 



Insoluble matter, 0*250 0*498 



99*350 99*437 



It is from this salt that the crystallised carbonate of soda is manufac- 

 tured. The ash is dissolved in boiling water until the solution has a 

 specific gravity of 1*255, (50° Twaddell). It is then run into a cistern, 

 where it is mixed with sufficient cold water to reduce the specific gravity 

 to 1*21, (42° Twaddell). This occasions the deposition of a quantity of 

 earthy matter. A small quantity of bleaching powder is then added to 

 the liquid, which causes another deposition. After this has been allowed 

 to settle, the solution is carefully decanted into another pan, and evapor- 

 ated till it attains a specific gravity of 1*27, (54° Twaddell). From this 

 it is run into another cistern, from which it passes into the crystallising 

 pans. The average time taken in crystallisation is eight days ; but it 

 of course varies very much with the season of the year and the state of 

 the atmosphere. The crystallisation is very much assisted by placing a 

 few bars of wood, two or three inches broad, on the top of the liquor. 

 The crystallised carbonate of soda yielded, on analysis, — 



i. n. 



Carbonate of soda, 36*476 36*931 



Sulphate of soda, 0*943 0*542 



Chloride of sodium, 0.424 0*314 



Water, 62157 62*213 



100000 100*000 



