POTASH. 81 



Tlie fixed alkalies were, until lately, regarded as 

 simple bodies, and one of the most brilliant disco- 

 veries of modern chemistry has been that which 

 showed them to be the oxides of peculiar metals. 



The decomposition of the alkalies was effected 

 by means of voltaic electricity. By acting upon a 

 very small piece of caustic potash, the metallic base 

 was liberated, and proved to be solid, malleable, and 

 having a high metallic lustre resembling mercury. 

 This new metal is called potassium. It differs 

 considerably in its properties from all the metals 

 previously known. It is lighter than water, and 

 has so strong an attraction for oxygen, that it almost 

 instantly attracts it from the atmosphere and re- 

 turns to the state of oxide. If thrown into water, 

 it produces a very singular phenomenon ; it decom- 

 poses the water so rapidly that an explosion takes 

 place, accompanied by a flame. The same effect is 

 seen if a globule of the metal is placed upon a 

 piece of ice. This metal can only be preserved by 

 keeping it under naphtha, a liquid that does not 

 contain oxygen as one of its constituents. 



Potash combines with all the acids forming neu- 

 tral salts. 



Nitrate of potash, called also nitre, or saltpetre, 

 is produced in considerable quantities naturally, 

 particularly in Egypt. It has also been produced 

 artificially by making beds of animal and vegetable 

 substances, mixed with calcareous and other earths. 

 In process of time, an efflorescence of nitrate of 

 potash appears, and is separated by lixiviation. By 

 the decomposition of these substances, nitrogen 

 is disengaged, which, uniting to the oxygen of the 

 atmosphere, forms nitric acid ; and this uniting to 

 the alkali furnished by the vegetables and soil, pro- 

 duces the nitre. Nitrate of potash has the property 



VOL. II. G 



