CHEMISTRY. 179 



which the metal operated on may differ from those 

 with which it is alloyed, and from which it is desired 

 to separate it. These differences may consist of the 

 facility or difficulty of oxidation, in their tendency to 

 volatilize, in the temperature required for fusion, and 

 in their relative specific gravities. 



Common Salt, 



Named also muriate of soda and chloride of sodium. 

 The waters of the ocean every where abound with it, 

 but in various proportions. All large lakes, such as 

 the Caspian, which have no outlet, have salt water. 

 Common salt, muriate of lime, and other bodies, 

 have not been proved to contain either acid or alka- 

 line matter, and consequently, according to the strict 

 logic of chemistry, ought to be regarded as com- 

 pounds of chlorine with metals. 



Saline Ingredients in Sea Water. 



By evaporating a pint of sea water we obtain 



Common salt . . 180-5 grains 



Muriate of magnesia 23' 



Sulphate of magnesia (Epsom salts) 15*5 

 Sulphate of lime (gypsum) ... 7*1 



226-1 grains. 



Soda, 



Named also mineral alkali, barilla, or kelp. Pure 

 soda is named carbonate of soda. It is the basis of 

 common salt. 



The properties of soda are very similar to those of 

 potash, with this remarkable difference, that with 

 soda, oils form a hard soap, while potash forms a soft 

 one. Both are used for the manufacture of soap and 



