SODA. 83 



carbonate, obtained by passing a stream of carbonic 

 acid gas through a solution of the former. 



Soda and potash considerably resemble each 

 other, but the former does not deliquesce so as to 

 liquefy, as potash does ; its crystals, however, efflo- 

 resce or fall to powder. It is used in the manufac- 

 ture of soap and of glass. 



Soda, also, like potash, consists of a metallic 

 base united t oxygen. The metal is called sodium. 

 It resembles potassium in most of its properties. 

 It unites with chlorine, forming chloride of potas- 

 sium ; this is the common sea-salt so much used in 

 food, and was, till lately, called muriate of soda. 



Common salt exists in immense quantities in na- 

 ture, both in the form of a rock, as rock-salt, which 

 is dug out of the earth in a solid form, and also 

 dissolved in the sea, from which it is obtained by 

 evaporation. 



Common salt is decomposed by sulphuric acid. 

 The sodium is converted into soda, by taking oxy- 

 gen from the water of the sulphuric acid, and the 

 chlorine combines with the hydrogen of the water 

 thus set free, and forms hydro-chloric acid gas, 

 which is the same with what has been called muri- 

 atic acid gas. This gas, absorbed by water, forms 

 muriatic acid. Hence, since muriatic acid was 

 thus procured from sea-salt, it was supposed to 

 exist in it, combined with soda, whence the name 

 muriate of soda. 



Soda unites with all the acids, forming neutral 

 salts, the most remarkable of which are the fol- 

 lowing : 



Sulphate of soda, called formerly Glauber's salts, 

 is formed abundantly in the process for procuring 

 the muriatic acid from common salt ; the sulphuric 

 acid which is employed uniting to the soda. 



