I] FERTILIZERS 16 



52 DETERMINATION. 



To 50 cc. of the clear filtrate in a beaker add 100 cc. of molybdate solution prepared 

 as directed under 4 (a). Place the beaker in a water bath, until the temperature 

 of the beaker's contents reaches 65 °C., remove from the bath and cool to room tem- 

 perature. Filter and wash the yellow precipitate of ammonium phosphomolybdate 

 4 or 5 times with 1% nitric acid. Dissolve the precipitate in 100 cc. of cold 2% 

 ammonium hydroxid, nearly neutralize with hydrochloric acid and add to the solu- 

 tion, drop by drop, with continuous stirring, 15 cc. of magnesia mixture prepared as 

 directed under 4 (C) and proceed as under 6. 



53 Volumetric Method. 



In an aliquot of the clear solution prepared as in 51, determine the phosphoric 

 acid as directed under 9. 



