WILLIAM GOSSAGE 25 



improvements in the manufacture of alkali 

 from common salt. The first of these was, 

 oxidising black-ash liquors by exposing them 

 in a state of minute division to the action of 

 atmospheric air. It is stated that sulphuret 

 of iron is held in solution in the above liquors 

 by sulphuret of sodium, but if the sulphuret of 

 sodium is converted into hyposulphite, or 

 sulphite, or sulphate of soda, the sulphuret of 

 iron is no longer soluble in such liquors. This 

 is effected by pouring the liquors through a 

 tower filled with small pieces of coke. The 

 second improvement was in separating ferro- 

 cyanide of sodium from other compounds of 

 soda contained in black-ash liquors, and also 

 thereby obtaining salts of soda free, or nearly 

 free, from such ferrocyanide. The mother 

 liquors after crystallising out carbonate of soda, 

 were further concentrated and crystallised. 

 The ferrocyanide is washed from such salts 

 by water, or by solution of carbonate of soda 

 filtering through the same, until sufficiently 

 free from the ferrocyanide to be suitable for 

 the production of white soda ash of good 

 quality. The washings are ultimately treated 

 with caustic lime, and the ferrocyanide 

 separated from the caustic soda by evapora- 

 tion and crystallisation. Third, obtaining 



