150 
REVIEW. 
“ The Oxide of Barium or Baryta . — Ba. 0 = 77, occurs native 
in combination with carbonic and sulphuric acids; but it 
may be procured by exposing the nitrate of baryta to the 
action or heat in a large porcelain crucible, when it remains 
behind in the form of a porous mass or gray powder. It has 
a strong alkaline taste, and combines rapidly with water, 
evolving much heat, and a hydrate is formed. 
cc Hydrate of baryta is soluble in 20 parts of cold and 3 of 
boiling water. This solution is a very delicate test for car- 
bonic acid, becoming quickly covered with a film of carbonate 
of baryta when exposed to the air. It is also powerfully 
alkaline and poisonous. 
u Carbonate of Baryta . — This compound, called Witherite , 
with the sulphate or heavy spar, is found in large quantities 
in Wales, Westmoreland, Cumberland, and other places. 
The carbonate, although sparingly soluble in water, is poison- 
ous, probably in consequence of its being acted on by the 
acid in the stomach. Artificially it may be formed by add- 
ing to the nitrate or chloride in solution, an alkaline 
carbonate : generally the carbonate of ammonia is preferred. 
“ Composition . — 1 atom Baryta . . . . = 77 
1 „ Carbonic acid . . . = 22 
Equivalent ... 99 
e( Chloride of Barium . — This compound is prepared by dis- 
solving the native carbonate in hydrochloric acid, filtering 
the solution, and evaporating till a film appears, then setting 
aside to crystallize. 
“ Composition . — 1 atom Barium . . . . = 6 9 
1 „ Chlorine . . . . = 36 
2 atoms water . . . . = IS 
Equivalent of crystallized salt . . 123 
u Properties and Uses . — The crystals of chloride of barium 
are flat four-sided tables, colourless, and transparent. About 
forty-three parts are taken up by 100 of water, and this 
solution is kept to test the presence of sulphuric acid or the 
sulphates ; it being so delicate that a millionth part of 
sulphuric acid may be detected by it. Sulphate of baryta is 
insoluble in every menstruum except hot concentrated sul- 
phuric acid. 
Nitrate of Baryta may be obtained in the same way as the 
above, substituting nitric acid for hydrochloric. It crystal- 
lizes in transparent, colourless, octohedrons, soluble in 8 parts 
