644 SEC. 13. CHEMISTRY. 



2738b. Model of Boot's Patent Pressure Blower. 



Thwaites $ Carbutt. 



2448. Models of Hydrochloric Acid Condensing 

 Towers, as erected at Messrs. Hutchinson's Alkali Works at 

 Widnes. Prof. Roscoe, F.R.S. 



2449. Model of Salt-Cake Furnace, with open roaster. 



Prof. Roscoe, F.R.S. 



2450. Model of Finishing (Alkali) Furnace. 



Prof. Roscoe, F.R.S. 



2451. Model of " Weldon " plant for the regeneration of Black 

 Oxide of Manganese in the Manufacture of Chlorine. 



Prof. Roscoe, F.R.S. 



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



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



is run into iron vessels, where a large part of the soda crystallizes 



out. Gaskell, Deacon, Sf Co. 



Composition : 



Na 2 C0 3 +10 Aq. 



2708. Mother Liquor. When the crystallization of the soda 

 is complete, the remaining liquid, or c ' mother liquor," is run off. 

 This contains nearly all the soluble impurities in the " soda ash.'* 



Gaskell, Deacon, $ Co. 



2709. Refined Alkali. To obtain this, soda ash is dissolved 

 in hot water, the clear solution is evaporated, when a mono- 

 hydrated carbonate of soda is precipitated, which is then calcined 

 and ground. Gaskell, Deacon, S? Co. 



2710. Red Liquor. In some cases the vat liquor is not 

 evaporated to dryness, the residual liquor (called, from its colour, 

 te red liquor") containing the greater part of the caustic soda, 

 sodium chloride, sulphate, sulphites, sulphide, and other impurities, 

 is separated, and subsequently treated for the production of caustic 

 soda. Gaskell, Deacon, Sf Co. 



2711. Oxidized Red 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. 



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. 



2713. Cream Caustic. The causticised liquor is concentrated 



