130 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



The white insoluble precipitate is calcium oxalate. Prove 

 this by a microscopical examination. Filter; if the quantity 

 is not too small, wash, dry, and heat to red heat on platinum- 

 foil. The calcium oxalate burns to calcium carbonate and 

 oxide. Therefore the residue, when moistened with a drop 

 >of water, shows a strong alkaline reaction and dissolves in 

 hydrochloric acid with effervescence. The filtrate from the 

 iron phosphate or the calcium oxalate may contain phos- 

 phoric acid, calcium, magnesium. 



1. To a portion of the nitrate add some uranyl acetate 

 solution. A yellowish-white precipitate of uranyl phosphate 

 indicates the presence of phosphoric acid. 



2. To the remainder of the nitrate add ammonium oxalate: 

 a white precipitate indicates calcium. H^at, then filter from 

 the precipitate, and make the filtrate alkaline with ammonia: 

 a crystalline precipitate of ammonium magnesium phosphate 

 indicates the presence of magnesium. 



Test for ammonia by warming with sodium carbonate 

 solution that part of the original hydrochloric acid solution 

 which was put aside. 



