V. MANUFACTURES. 645 



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. 



2714. White 60 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. 



2715. White 7O 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, $ Co. 



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

 product from the manufacture of bicarbonate of soda or from the 

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

 fied and settled, and concentrated by evaporation. 



Gaskell, Deacon, fy Co* 



Composition : 



CaCl 2 . 

 Aq. 



2472. Samples of Bicarbonate of Soda unground ; also 

 ground and dressed. John Hutchinson $ Co. 



2471. Samples illustrative of Mond's process for the recovery 

 of sulphur from alkali (vat or tank) waste : 



1 . Alkali (vat or tank) waste before oxidation. 



2. Alkali (vat or tank) waste after oxidation. 



3. Sulphur liquor. 



4. Precipitated sulphur. 



5. Sulphur in bulk. 



6. Roll sulphur. 



John Hutchinson fy Co. 



2477. Soda Waste, Alkali Waste, Black Ash Waste, or 

 Tank Waste. Insoluble residue formed in the second or black 

 ash stage of Leblanc's process for obtaining soda from common 

 salt. John Hutchinson fy Co. 



