BARIUM. 57 



Carbonate of soda ^ NaO-j-COa+lOHO. Prepared by lixiviating 

 the ashes of marine plants, and evaporating ; — this is known under 

 the commercial names of barilla^ and kelp^ which contain many im- 

 purities. A purer variety is made by heating together sulphate of 

 soda, lime, and sawdust in a reverberatory furnace. Sulphuret of 

 calcium, sulphurous acid, and carbonate of soda are formed. This 

 salt is in large rhombic crystals, very soluble in water, of a caustic 

 alkaline taste, and alkaline reaction. 



Bicarbonate^ NaO+2C03+HO, — formed as the bicarbonate of 

 potassa. Less soluble than the carbonate. 



Sesquicarbonate, 2NaO+3C02+4HO. — Occurs native. 



Sulj)hate of soda — Glauber's salt, NaO-f SOg-f 1 OHO ; the residue 

 left in the process for making hydrochloric acid. A very soluble 

 salt; more so at 90° than at 212°. There is also a bisulphate. 



The nitrate of soda is very similar in properties to the nitrate of 

 potash. The three phosphates are spoken of under the head of 

 phosphorus. 



Chloride of Sodium, — Common Salt, — is found in sea-water and 

 saline springs ; it occurs also as a mineral, under the name of rock 

 salt ; — procured by evaporation from its solution. The crystals 

 decrepitate when thrown on hot coals ; are very soluble in water, 

 and are slightly deliquescent. Iodine, bromine, sulphur, and fluorine, 

 also combine with sodium. 



Tests for soda and its salts. — All the soda salts are soluble ; they 

 communicate a yellow colour to the blowpipe flame. Soda forms 

 with sulphuric acid, the well known Glauber's salt. Soda is less 

 soluble than potassa. 



LITHIUM. 



Prop. — A white metal resembling sodium, procured by electrical 

 action from lithia, its protoxide, which is found in petalite, and 

 some few other rare minerals. The hydrate of lithia generally re- 

 sembles the hydrates of soda and potassa, but is less soluble. 



Test. — It communicates a carmine-red colour to outer flame of 

 blowpipe. 



S E C T I O N II. 

 CLASS II. 

 METALS OF THE ALKALINE EARTHS. 

 This class includes Barium, Strontium, Calcium, and Magnesium. 



BARIUM. 



Procured by means of mercury from baryta or its carbonate, 

 through the agency of galvanism or heat. 



