MINERALOGY^ 



307 



1. Potash. This substance is obtained from the ashes of 



such plants as do not grow within the influence, or are 

 not contiguous to the sea ; its base is allied in some 

 respects to the Metals, it somewhat resembles Quick- 

 Silver, but is lighter than water ; and is combined with 

 Oxygen. 



Potash is abundantly obtained from various vegetables ; 

 it is also found in a considerable number of earthy sub- 

 stances, and enters into the composition of some of the 

 oldest of the primitive Rocks, it is likewise found combined 

 with Soda : Potash combined with Nitric Acid, forms that 

 useful and well-known substance, Nitre, or Salt-Petre. 



2. Soda. The base of Soda resembles silver, It is lighter than 



water, and is combined with Oxygen. 



This substance is found combined with several Earthy- 

 Minerals, as also with Potash ; it is exceedingly abundant, 

 being the basis of common Salt, and is the saline residue of 

 most plants growing on the sea shore. 



METALS. 



Metals having never been decomposed, are supposed when 

 pure to be simple substances. The number of known 

 Metals are Twenty-seven, they are found in a native state, 

 either simple, consisting of only one substance ; or compound, 

 when composed of two or more substances. All the Metals 

 are much heavier than the Earths, the heaviest of the latter 

 not exceeding five times the weight of water ; and the light- 

 est of the Metals being six times heavier than water. Those 



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