BOTANIC PHYSICIAN. 
_ table colors to a green. In the fire, it is infusible by itself; how~ _ 
: _ when mixed with the other earths; it combines with almost all 
_  Limeis used in medicine as an antacid, as an astringent, and as a re- 
_ ‘Medy in calculus. It is given in the form of solution in water. Some 
_ aerid than the pure lime, oe ae ee 
_.-Baryres is distinguished by its great specific gravity, which is 
superior to that of every other fossil not metallic. In nature, it is 
always found combined with the sulphuric or carbonic acid.» When 
pure, it isin the form of a very fine white powder; it is fusible and 
soluble in 20 parts of water, its solution changing the vegetable co- 
_ fors to a green ; its attractions to the acids are in general much sue 
*  perior to-those of any of the other earths. : 
_ _. Barytes has a much more powerful action on the system than the 
_ @ther earths have. Even in a smal] dose it oceasions vertigo, insen- 
_ ‘sibility, and other nervous symptoms. From this circumstance, as 
from its great specific gravity, some have supposed that it is 
etallic oxyd, which we have hitherto been unable to decompose. 
_ Srronrires is, in many of its properties, similar, to barytes. Like 
it, it is found in nature combined with sulphuric and carbonic acids, 
and these compounds are distinguished by great specific gravity. It 
ds fusible, but less soluble, requiring 200 parts of water for its solu- 4 
_. tom. Its saline combinations are, on the contrary, in general, more 
soluble than those of barytes. It has no poisonous quality, or does 
not appear to exert any great activity on the animal system. Re 
‘The Atkans are somewhat analagous in their properties tothe — 
_ earths; they are distinguished by the following characters. They 
have a penetrating acrid taste; change the vegetable colors toa 
- green; have a strong attraction for water, unite with oils, and com- 
_ bine with the acids, forming neutral salts. There are three sub- ee 
Stances of this kind; potash, soda, and ammonia. There is reason 
to believe that they are compounds. One of them, ammonia, is _ 
proved to consist of azot and hydrogen, which renders probable the 
inion that the others are also compounds, though they have not 
hitherto been decomposed. . te Cag 
__. Porasmis the most powerful of these substances : it is solid, and 
_ trystalizable, of a white color, is highly acrid and caustic, has so _ 
Strong an attraction to water.as to take it from almost any other 
uce, It melts at a moderate temperature ; by fusion with sili- 
1it forms glass: it has a stronger attraction than either 
alkalies for the acids, and therefore the compounds it c 
Se ae 
estroy ta saline mass remains, which consists princi| 
ash. There is. reason to 
ponent principle of vegetable matter, it is only insome vegetables, and — 
never in such quantities as are afforded by the combustion. : 
The physical characters ef sopa are so precisely the same with 
