424 -Dr. Prout’s description of an acid principle 
transparent, and of a deep garnet red colour ; but by reflected 
light, their two broadest opposite faces appear of a brilliant 
green, closely resembling that of the wings of some of the 
beetle tribe, as for example, of the Cetonia aurata , while their 
other two opposite faces appear of a dull reddish brown colour; 
or if the light be very strong, slightly green. This pecu- 
liarity seems to be possessed in a greater or less degree by all 
the other alkaline, and perhaps earthy salts ; and doubtless 
depends upon the structure of the crystals. The purpurate 
of ammonia is soluble in about 1500 parts of water at 6o°, 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 purpurates 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 purpurate of ammonia 
above-mentioned. This salt 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 soluble than the purpurate of potash. Three thousand 
times its weight of water at 6o°, did not completely dissolve 
