140 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



nitrate solution: (1) yields a flocculent precipitate of hypo- 

 xanthine-silver, (2) does not, the solution only becomes 

 faintly opalescent. The gelatin prevents the precipitation of 

 the hypoxanthine-silver completely. 



in. THE MINERAL CONSTITUENTS OF BONE. 



Make half of the hydrochloric acid solution alkaline with 

 ammonia, then acidify with acetic acid: the precipitate 

 formed dissolves on the addition of ammonia, leaving a slight 

 residue of ferric phosphate, which presumably comes from 

 the blood contained in the bone (at least in part from this). 

 Filter and use a small part of the filtrate to test for phos- 

 phoric acid, the greater part to test for calcium and magne- 

 sium. 



(a) The flocculent precipitate is washed and dissolved in 

 a few cubic centimeters of dilute hydrochloric acid. Test for 

 iron in the solution with potassium ferrocyanide, and for 

 phosphoric acid with ammonium molybdate. 



(6) Filtrate from the ferric phosphate. 



1. Test for phosphoric acid by adding uranyl acetate 

 solution: yellowish-white precipitate of uranyl phosphate 

 (U0 2 )HP0 4 . 



2. Precipitate the calcium as calcium oxalate, CaC 2 4 +H 2 0, 

 by the addition of sufficient ammonium oxalate. To the 

 clear filtrate (made clear by warming and pouring repeatedly 

 through the filter), which must remain clear on the further 

 addition of ammonium oxalate, add ammonia to alkaline 

 reaction: a crystalline precipitate of ammonium magnesium 

 phosphate, MgNH 4 P0 4 +6H 2 0, separates after some minutes. 



The detection of the mineral constituents of bone may 

 also be made with the bone-ash. For this purpose 0.5 to 1 g. 

 of the bone-ash is sufficient. The carbonates are more easily 

 recognized by this method. The course of the examination 

 is the same. 



