BARIUM. Jsf, 



ORDER II. 



METALLIC BASES OF THE ALKALINE EARTHS. 



SECTION IV. 



BARIUM. 

 Eq. 856.9 or 68.66; Ba. 



Barium, the metallic basis of barytes, was obtained by Davy 

 in 1808, by the voltaic decomposition of moistened carbonate of 

 barytes in contact with mercury; it may likewise be procured by 

 passing potassium in vapour over barytes heated to redness in an 

 iron tube, and afterwards withdrawing the reduced barium, which 

 the residue contains, by means of mercury. The latter metal is 

 separated by distillation in a retort, care being taken not to raise 

 the temperature to redness, for then the barium decomposes 

 glass. Barium is a white metal like silver, fusible under a red 

 heat, denser than oil of vitriol in which it sinks. It oxidates 

 with vivacity in water, disengages hydrogen, and is converted 

 into barytes. It is named barium (from /3apuy, heavy), in allu- 

 sion to the great density of its compounds. 



Barytes: BaO ; 956.9 or 76.66. This earth exists in several 

 minerals, of which the most abundant are sulphate of barytes 

 or heavy spar, and the carbonate of barytes or witherite. The 

 earth is obtained in the anhydrous condition and pure, by cal- 

 cining nitrate of barytes, at a bright red heat, in a porcelain 

 retort, or in a well covered crucible of porcelain or silver, but 

 not of platinum. If the calcination is not carried sufficiently 

 far, a combination remains of barytes and nitrous oxide (Berze- 

 lius), which has been mistaken for peroxide of barium. The 

 iodate of barytes also may be calcined in a porcelain retort, for 

 barytes ; it is, I find, more easily decomposed than the nitrate, 

 and has not the troublesome property of fusing and swelling up, 

 when heated, which the latter salt possesses. The iodine comes 

 off, with oxygen, and may be recovered. Iodate of barytes 

 itself is obtained, as an insoluble precipitate, on adding chloride 

 of barium to iodate of soda (page 390). Barytes is a grey 

 powder, of which the density is about 4. When heated to 

 redness in a porcelain tube, and oxygen passed over it, it ab- 



