SODA-ASH. 



Hydrate of lime 6.67 



Sulphide of sodium 1.78 



Peroxide of iron 3.70 



Silicate of magnesia 6.91 



Coal 2.60 



Sand 3.09 



Water 3.45 



99 



100.31 

 The results of Brown and Unger agree closely, when we 

 consider how such materials are likely to vary in composition 

 according to circumstances, but the amount of the carbonate 

 of lime should be halved, as Brown proved it to be caustic 

 lime, and the half added to the caustic soda, which would bring 

 the total amount of carbonate of soda in the first analysis to 

 nearly 40 per cent. Brown gives it at 35|. 



The following table, from Brown, shows the composition of 

 the different products of the soda manufacture. 



Analysis No. 1 is the salt obtained by evaporating the ex- 

 tract of the crude soda to dryness at 212°, and then heating 

 in a calciner, which makes No. 2, soda-ash. Or, the extract 

 is evaporated nearly dry, the mother-liquor drained off from 

 the crystals ; the dried residue, 3, is heated in a furnace, 4. 

 By repeated solution, evaporation and calcination of the crys- 

 tals, a better kind, 5, is produced, and by crystallizing the 

 purer kind, soda, 6 results ; and when this is calcined, the 

 best product, 7, is obtained. 



R. A. Tilghman applied the decomposing power of steam to 



