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 shora. 



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. Thoss 



V 2 



