No. 4. Slack, or small coal from the Lancashire coalfield ; used 

 in combination with limestone for converting salt cake or sulphate 

 of soda into carbonate of soda. 



No. 5. Black ash, or ball soda, containing about 24 per cent, 

 of soda, produced by fluxing together in a suitable furnace a 

 mixture of salt cake or sulphate of soda, limestone, and slack, by 

 which ID cans the sulphate of soda is converted into carbonate of 

 soda, the carbonate of lime of the limestone into calcium sulphide, 

 and the slack into coke. 



No. 6. Vat liquor. A saturated solution of soda produced by 

 lixiviating " black ash " or " ball soda " with warm water in iron 

 tanks or vats ; when the solution is saturated it is run off into 

 iron pans to be boiled down, the calcium sulphide and unburnt 

 coke of the " black ash " being left behind in the vat as " tank" 

 or " vat waste." 



No. 7. Salts, or crude carbonate of soda, obtained by boiling 

 down " vat liquors " in iron pans, heated either externally or by 

 passing the flame over the surface of the liquor in the pan. 



No. 8. Soda ash, or finished carbonate of soda of commerce, 

 containing 58*5 per cent, of real alkali, produced by gradually 

 heating to redness in a reverberatory furnace " salts " or crude 

 carbonate of soda. 



No. 9. Salt, as used in the " Hargreaves " process. The salt 

 is placed in a moist state on drying floors, and when dried into 

 hard flat pieces is broken by machinery. 



No. 10. Salt cake, or sulphate of soda containing 99 per cent, 

 of real sulphate, made without the use of sulphuric acid by the 

 " Hargreaves " direct action process. Salt maintained at a red 

 heat in iron cylinders is exposed to the direct action of sul- 

 phur dioxide, air, and steam. The hydrochloric acid from the 

 salt is condensed as in the ordinary process. 



144. Soda crystals and concentrated crystal soda. 

 1888. Exhibited by Brunner, Mond, Co. 



145. Group of soda crystals of large size. Under 

 glass shade. 



1888. Exhibited by GasJcell, Deacon, fy Go. 



146. Caustic soda ash, containing about 12 per cent, 

 caustic soda, 76-80 per cent, carbonate of soda, total 

 strength about 54-56 per cent. Na 2 0. Black ash is lixi- 

 viated in iron tanks, the liquor thus obtained is boiled 

 down in open wrought- iron pans, and, as the crystals 

 fall," they are fished out and calcined in an open furnace. 



1876. Exhibited Inj James MuspraM fy Sons. 



