72 Qualitative Tests. i Sd 
2. AgNOs precipitates light-yellow AgsPOs, solu- 
ble in HNOs and NH:OH. 
3. (NH):MoO.+HNOs: precipitates yellow ammon- 
ium phospho-molybdate ; composition variable. The pre- 
cipitate is soluble in NH:+OH, in excess of phosphoric 
acid, and is prevented by organic substances, such as tar- 
taric acid. 
Pyrophosphate—1. MgSOs precipitates white 
Mg:P:0;, soluble in an excess of either solution. NH:OH 
fails to precipitate it from these solutions. On boiling 
it separates again. By this reaction pyro can be detected 
in the presence of phosphoric acid. 
2. (NH:):MoO:+HNOs does not give a precipitate — 
until orthophosphate is formed. Most of the pyrophos- 
phates of the heavy metals (Ag an exception) are solu- 
ble in alkali pyrophosphates (distinction from ortho- 
phosphates). | | 
3. AgNO: precipitates white Ag:P:0:, soluble in 
HNO: and NH:OH. Addition of an alkali aids the pre- 
cipitation. 
Metaphosphoric Acid.—1. Magnesia mixture gives 
no precipitate. 
2. (NH:):MoO:+HNOs gives no precipitate. 
3. AgNOs precipitates white AgPOs, soluble in al- 
kali metaphosphate solutions (distinction from pyro- 
phosphates). 
4. Albumen gives a precipitate (distinction from 
ortho and pyrophosphates). 
5. Fusion with Na:COs converts meta and pyro 
into orthophosphates. 
POTASSIUM, K. 
WITH THE BLOWPIPE. 
Flame.—Violet, except borates and phosphates. 
