214 JAMES SHANKS 



2. To get as much as possible of the soda 

 out as carbonate. 



3. To get concentrated liquors. 



To achieve these ends it has been found 

 that the lixiviation should be performed: 

 (i). As quickly as possible. 



). With a minimum quantity of water. 

 At as low a temperature as 

 possible. 



There have been three arrangements of 

 apparatus for the purpose. 



The first, the oldest, and the one which 

 was universally used in Great Britain, 

 consisted of tanks arranged tier above tier. 

 The black-ash was put into the lowest tank, 

 and after being washed with the lyes from 

 the tanks above it, yielding a concentrated 

 solution, the black-ash was emptied by hand 

 labour with spades from the lowest tank to 

 the one next above it, and so on, but this 

 operation was tedious, costly, and ineffective. 

 It entailed much labour in emptying the 

 black-ash from one vat to another, the 

 handling of the ash caused the balls to break 

 up and so become dense instead of retaining 

 their porosity, and the moist residues were 

 exposed to air, and so the sodium carbonate 

 was to some extent decomposed. The 



