H MANUFACTURE iff 



m boiler, and put aside. By this process fro, 



to ISQlbs. of soda may be obtained from iOOlbs. of 



sulphate of soda. 



MANUFACTURE OF POTASH. 



Potash, or the fixed vegetable alcali, exists as an 

 ingredient, in very small quantity, in many mine- 

 rals. It is also obtained from the tartar, or from 

 lees of wine, in which it is called salt of tartar. 



But the great supply of this substance is procured 

 frc\fli the ashes of burnt vegetables. 



In many districts of England and Irdafid they 

 burn the common fern to ashes, which they mould 

 up with a little water, into balls of about three or 

 four inches in diameter ; these are called ash balls, 

 and are the rudest preparation of this alcali. 



The potash of commerce, or black potash, is 

 always procured from the combustion of wood, and 

 can, therefore, only be made in those countries 1 where 

 wood is very plentiful, as Poland, Russia, and Ger- 

 many. This country is chiefly supplied from Ame- 

 rica. The ashes of burnt wood are put into a 

 cistern with water, arid a strong lixivium is rriade. 

 After a time, the water, holding the alcali in solu- 

 tion, is drawn off; leaving the impurities behind. 



Potash is converted into a purer state by calcining 

 it in a reverberatory furnace. It becomes then dry, 

 porous, considerably caustic, extremely deliques- 

 cent, and of a beautiful bluish colour, from which 

 it is called pearl ash. 



All these are carbonates of potash. 



To obtain potash in a state of perfect purity, or 

 uncombined with carbonic acid, the carbonate must 

 be boiled with twice its weight of quicklime to de- 



