THE FAECES. 215 



the flask, until the evolution of gas has entirely ceased. The 

 fluid is then placed in a porcelain dish, evaporated to a 

 volume of about 100 cc., 10 g. of ammonium nitrate and 

 50 cc. of the ammonium molybdate solution added, and let 

 stand at room temperature or at 60 to 70 till next day. 

 Decant through a small filter, and wash the dish and filter a 

 few times with a solution containing 150 g. of ammonium 

 nitrate and 10 cc. of nitric acid in the liter. Dissolve the 

 yellow residue in the dish in dilute ammonia (1:3) by warm- 

 ing, filter the solution through the same filter, and wash dish 

 aiid filter with ammonia. Now add to the solution con- 

 tained in a beaker, whose volume should at most amount to 

 100 cc. (preferably less), hydrochloric acid until a yellow pre- 

 cipitate begins to separate again, then about one-fourth of 

 the volume of ammonia and 10 cc. of magnesium chloride mix- 

 ture. Filter next day, transfer the precipitate of MgNH 4 P0 4 

 with the help of the filtrate completely to the filter, then 

 wash with dilute ammonia (1:3) until a portion of the filtrate 

 when acidified with nitric acid is no longer rendered turbid with 

 silver nitrate solution or only faintly, dry, and ignite strongly. 

 The magnesium pyrophosphate obtained must be white, or 

 at most a very faint gray. If it is not possible to attain this 

 by ignition alone, add a little nitric acid, dry, and ignite again. 

 111.36 parts of Mg 2 P 2 7 correspond to 31 parts of phos- 

 phorus =71 parts of P 2 5 . 



(6) Instead of fusing with the oxidizing mixture the 

 organic matter may also be destroyed, according to A. Neu- 

 mann, 1 by heating with sulphuric acid and ammonium 

 nitrate. To 2 to 3 g. of the material take 15 cc. of sulphuric 

 acid and 15 g. of ammonium nitrate. As in the nitrogen 

 determination, the powdered fa3ces are placed in a Kjeldahl 

 flask, washed down with a little water, 15 cc. of sulphuric 



1 Chem. Centralbl., 1898, 1, 219. 



