IV. TECHNICAL. 535 



is separated, and subsequently treated for the production of caustic 

 soda. Gaskell, Deacon, fy Co., Lancashire. 



2711. Oxidized Bed Liquor. The sulphides/sulphites, &c. 

 in the red liquor are wholly or partially oxidized by blowing air 

 through the red liquor in deep iron vessels. 



Gaskell, Deacon, fy Co., Lancashire. 



2712. Causticised Liquor. After oxidation the red liquor 

 is diluted to about 1 080 specific gravity, and rendered caustic by 

 agitation in contact with caustic lime. 



Gaskell, Deacon, fy Co., Lancashire. 



2713. Cream Caustic. The causticised liquor is concentrated 

 by evaporation until the solution sets hard on cooling, and tests 

 60 per cent, of alkali. During this concentration some of the 

 sodium sulphate and a little carbonate are precipitated, and are 

 ladled out, and any further oxidation required is effected by the 

 addition of nitrate of soda. 



Gaskell, Deacon, fy Co., Lancashire. 



2714. White 6O per cent. Caustic Soda. To obtain this 

 the causticised liquor is concentrated until the unevaporated por- 

 tion fuses, when the iron (which has probably been held in solu- 

 tion by combination with cyanogen), and the greater part of the 

 alumina and silica, are precipitated and allowed to settle ; the clear 

 fused caustic soda, containing some sodium sulphate and chloride, 

 is packed in iron drums. 



Gaskell, Deacon, fy Co., Lancashire. 



2715. White 70 per cent. Caustic. This is obtained in 

 the same manner as white 60 per cent., except that care is taken 

 during the concentration to remove sufficient sodium sulphate and 

 chloride to enable the resultant caustic to be of the required 

 strength. Gaskell, Deacon, fy Co., Lancashire. 



2716. Chloride of Calcium. This is obtained as a bye 

 product from the manufacture of bicarbonate of soda from the 

 " Weldon " process. The solution of chloride of calcium is puri- 

 fied and settled, and concentrated by evaporation. 



Gaskell, Deacon, $ Co., Lancashire. 



Composition: 



CaCl 2 . 

 Aq. 



2717. Soda Crystals, or Washing Soda. To obtain these 

 crystals, soda ash is dissolved in hot water, and the clear solution 



