390 CARBONATES. 



(g.) By adding carbonate of soda to the hydroguretted sulphur et 

 of baryta, formed by decomposing the native* sulphuret, by ignition 

 with charcoal, as already described. 



3. PROPERTIES. 



(a.) The artificial carbonate is a white powder whose specific 

 gravity is 3.763 ; that of the native, 4.3 or 4.4. 



(b.) Caloric. Dr. Hope often expelled the carbonic acid by 

 the well managed heat of a smith's forge,f and obtained the caustic 

 earth. 



(c.) Fusible on charcoal, losing at the same time, some of the car- 

 bonic acid. 



(d.) MixJ fine powder, of either artificial or native carbonate of 

 baryta, with about its volume of lampblack, and add lamp oil, until 

 the mass can be rolled into a ball ; place it in a black lead crucible, 

 surrounding it with lampblack or charcoal powder, and lute on a 

 cover ; heat the whole in a good forge or wind furnace for an hour. 

 The ball still retaining its form, may now be taken out, and boiling 

 hot water added ; it will slack powerfully, and when cold, will shoot 

 into beautiful crystals. 



(e.) Soluble in 4300 parts of water at 60, in 2300 at 212 ; wa- 

 ter impregnated with carbonic acid, dissolves with some facility that 

 which has been recently precipitated, and takes up |^ ; it is 

 precipitated and redissolved exactly in the same modes that were 

 mentioned under carbonate of lime. 



(/.) Tasteless no effect on test colors. 



(g.) A violent poison, not known in common life, except in those 

 places where it is found native. 



(h.) Decomposed by most of the acids with effervescence, produc- 

 ing salts ; there are some peculiar circumstances which will be men- 

 tioned under the other barytic combinations. 



* The native carbonate is found in Cumberland, (England,) at Alston Moor; in 

 Lancashire, at Anglezark, near Chorley ; and in other parts of England ; in Scotland, 

 and in Sweden. It was announced, (Am. Jour. Vol. II,) as existing near Lexington, 

 Kentucky, but this has not been confirmed. It is commonly found in metallic veins 

 along with sulphate of baryta, and various metallic substances. Its sp. gr. is 4.33 or 

 4.4, whence it appears that it is much heavier than the artificial ; it is a little harder 

 than carbonate of lime, but softer than the fluate. 



t Dr. Priestley, by steam, passed over the ignited artificial carbonate, reduced it 

 to the state of baryta; in this case, the attraction of the water for the base, aids the 

 decomposition. 



t In this process, the carbonic acid is not only expelled, but in part decomposed 

 by the carbon, which, with one proportion of the oxygen, produces carbonic oxide. 

 The process I find to be constantly successful, and it is very eligible when we wish 

 to obtain either a solution or crystals of baryta. We may begin with the sulphate, 

 decompose it by ignition with charcoal; form the sulphuretted hydro-sulphuret ; de- 

 compose this by an alkaline carbonate, and thus obtain the carbonate of baryta for 

 this experiment. 



