POTASH. 71 



a beautiful violet colored flame. Potassium oxi- 

 dizes readily in the air, and in water; in the 

 latter case, the hydrogen being liberated, and 

 the oxygen of the water uniting with the potas- 

 sium, forms the hydrate of potassa the caustic 

 potash of commerce. 



Potash, when strictly pure, is white and highly 

 caustic, destroying both animal and vegetable 

 substances, when brought in contact with it. It 

 melts at a red heat, and assumes a crystalline 

 appearance upon cooling. It requires half its 

 weight of water to enter into solution, which is 

 accompanied with the evolution of considerable 

 heat. It is soluble also in alcohol. Solutions of 

 potash are highly alkaline, neutralizing the 

 strongest acids. 



Potash is a valuable element in the composi- 

 tion of plants. The ash of cultivated plants is 

 generally richer in this substance than is that of 

 those growing spontaneously. Potash is found 

 in most mineral waters, in most soils, and always 

 in plants. Potash is often found in nature, in 

 combination with nitric acid, forming nitre, or 

 saltpetre, which, in some hot countries, forms in- 

 crustations on the surface. Such incrustations 

 are found in India, Arabia, and South America ; 

 also in certain caverns in Ceylon, and some other 

 parts of the world. Saltpetre, as found in these 

 incrustations or deposits, is always contaminated 



