28 Description of an Acid Principle 
in a greater or less degree by all the other alkaline, and perhaps 
earthy salts; and doubtless depends upon the structure of the 
erystals. The purpurate of ammonia is soluble in about 1500 
parts of water at 60°, but in boiling water is much more soluble. 
The solution is of a beautiful deep carmine, or rose red colour. 
In pure alcohol and in ether, it is little if at all soluble. The 
aqueous solution has a slightly sweetish taste, but no smell. By 
adding this aqueous solution of the purpurate of ammonia to 
neutral saline solutions of other bases, most of the following pur- - 
purates were formed. 
Purpurate of potash. When a saturated boiling solution of 
the purpurate of ammonia is added to a solution of the bicar- 
bonate of potash, a dark brownish red precipitate takes place, 
which is the purpurate of potash. If, however, this salt be slowly 
formed, it may be obtained in a crystalline form; and the crystals 
appear to possess the same peculiarity. with respect to colour, as 
those of the pupurate of ammonia above mentioned. This sal 
is much more soluble than the purpurate of ammonia. ; 
Purpurate of soda. This salt, when obtained by the same 
means as the purpurate of potash, is of a dark brick red colour. 
It may, however, be obtained in crystals. It is much less solu- 
ble than the purpurate of potash. Three thousand times its 
weight of water at 60° did not completely dissolve it. The co- 
lours of the solutions of this salt, and of potash, differ slightly 
from one ‘another, and also from that of the purpurate of am- 
monia; but it is not easy to describe these differences so as to ° 
render them intelligible. 
Purpurate of lime. This salt, when obtained by adding a boil- 
ing saturated solution of the purpurate of ammonia to a solution 
of the muriate of lime, exists in the form of a powder much re- 
sembling in colour the crust of the lobster before it is boiled. This 
salt is but little soluble in cold water; but in boiling water it is 
more soluble, and the solution is of a beautiful reddish purple 
colour, 
Purpurate of strontian. This salt obtained as above, with the 
nitrate of strontian, exists in the state of a dark brownish red 
powder, with a slight tinge of green. It seems to be more solu- 
ble than the purpurate of lime, and forms a purple solution. 
Purpurate of barytes, Obtained as before described, with the 
acetate of barytes, this salt assumes the form of a dark green 
powder, not apparently differing much in point of solubility from 
the purpurate of strontian ; and forming, like that salt, a purple 
solution. 
Purpurate of magnesia. This is a very soluble salt. Its 
solution is of a beautiful purple. ; 
Purpurate of alumina. When a solution of the purpurate of 
ammonia 
