POTASSIUM. 233 



CLASS I. 



POTASSIUM. 

 576. DESCRIPTION. Potassium is a 



bluish White metal > H g hter than Water > 



solvents; and soft, like bees-wax. Like wax. it is 



occurrence? 



also converted by the heat of an ordinary 

 fire into vapor. Water and acids dissolve it readily. 

 The metals of this and the folloAving groups, were dis- 

 covered by Sir Humphrey Davy, early in the present 

 century. They were first produced by the galvanic 

 process. Potassium is a constituent of many rocks, 

 of all fertile soils, and of the ashes of plants. The 

 more important minerals which contain it, are men- 

 tioned in Chapter III. 



577. PREPARATION. Potassium is made 



flow is potas- 



sium pre- from carbonate of potassa, by removing 

 pared? j tg car b olu ' c acid and ox- 



ygen. This is accomplished by 

 heating intensely with charcoal, which 

 removes both in the form of carbonic oxide. 

 The metal which accompanies the gas, in the form 

 of vapor, is condensed by naptha, instead of water. 

 The process is essentially the same as that for preparing 

 phosphorus, but requires apparatus beyond the reach of 

 the ordinary experimenter. Cream of tartar, if heated, 

 is converted into a nearly suitable mixture of carbonate 

 of potassa, and pure carbon, for this purpose. A small 

 quantity of charcoal, in fragments, is added, and the 

 whole heated intensely in an iron retort. 



