212 JAMES SHANKS 



about forty-two parts of caustic lime is added 

 for each fifty-four parts of carbonate of soda 

 present therein, and mix them well together. 

 A violent reaction takes place, and the 

 mixture becomes a pasty mass. This is 

 treated as above until it no longer shows the 

 presence of sulphide. In working with 

 solutions of carbonate of potash about forty- 

 two parts of caustic lime are used for each 

 seventy parts of carbonate of potash. 



Second, the abstraction of solutions of 

 caustic soda and caustic potash from such 

 dessicated compounds by lixiviation and 

 filtration, such solutions being thereby 

 obtained at higher gravities than similar 

 solutions have hitherto been obtained from 

 mixtures of solutions of carbonate of soda or 

 carbonate of potash with lime. The dry 

 powder withdrawn from the furnace is mixed 

 with water or with weak solution of caustic 

 soda, and by injection of steam therein, 

 together with thorough agitation, the mixture 

 is reduced to the consistence of cream ; this 

 mixture is transferred on to a filtering bed, 

 under which a partial vacuum is formed. 



When the filtration has proceeded to such 

 an extent that the solid matter is no longer 

 covered with the supernatant fluid, water is 



