POTASH. 275 



poured on fresh ashes, in order that a greater pro- 

 portion of salt may be obtained before the solution 

 is subjected to ebullition. 



The water strongly impregnated with alkaline 

 matter is then evaporated in iron pots of from sixty 

 to eighty gallons capacity. During the progress of 

 the evaporation more of the ley is, from time to time, 

 thrown into the boilers until they are considered to 

 be sufficiently charged with alkali* The water being 

 thus driven off by the action of fire the residue con- 

 cretes into a hard substance, and adheres so tenaci- 

 ously to the sides and bottom of the pot as to require 

 much labour to separate it. This was formerly a 

 most tedious and troublesome part of the process, 

 and could only be accomplished by the use of mallets 

 and chisels. Accident, however, discovered to the 

 manufacturer a method of avoiding all this trouble 

 by disengaging the potash when in a liquid form 

 from the boiler. For this purpose, after the water is 

 evaporated from the alkali, the action of the fire is 

 increased until the boiler becomes red hot and the 

 potash fuses ; in this state it is conveniently taken 

 out with iron ladles and cast on a dry floor paved 

 on purpose. Before fusion the salt is brown; in 

 fusion it takes various dark hues ; indeed the potash 

 thus produced is of a colour sometimes approaching 

 to black: yet it is found that a solution of it is nearly 

 colourless. The extractive matter, though not con- 

 sumed, having been burnt to an indissoluble car- 

 bonized state, subsides, leaving the water impregnated 

 with the salt. 



For making potash of a superior quality the 

 ashes are more carefully burnt and rendered suf- 

 ficiently pure to produce a fine alkali. After con- 

 tinuing the intense fusing heat for some hours, the 

 salt, which under fusion takes the appearance of a dark 

 brown or blackish fluid, will at length concrete into a 



