22 



PRACTICE 10. 

 DETERMINATION OF NITROGEN IN ANIMAL EXCREMENTS : SOLID AND LIQUID. 



Each group of students will work upon one of the following : 



1. Horse excrements. 



2. Steer excrements. 



3. Cow excrements. 



4. Sheep excrements. 



5. Swine excrements. 



6. Poultry excrement and fresh cow's milk. 



7. Human excrements. 



8. Wheat straw and manger refuse (for bedding). 



Record age and condition of animals and food rations as nearly as 

 possible in all cases. 



For solid excrements : Weigh out 10 grams of fresh substance on filter 

 paper, placed on a watch-glass, and transfer both paper and excrement to 

 a Kjeldahl flask. 



For liquid excrement: Measure out 10 cc. and place in a Kjeldahl 

 flask. Compute weight from specific gravity .................... gm. 



Solid Liquid. 



Titrations (1) .............. cc. NH 3 Titrations (1) .............. cc. NH 8 



(2) .............. cc.NH 3 (2) ............ cc.NH 3 



Average ................... cc. NH 3 Average ............... . . cc. NH 3 



Calculate the results obtained and with these record the results obtained 

 by three members of each group as indicated upon the following page. 

 Value N at 15 cents per pound. 



10 tons alfalfa hay contain ......................... Ib. N 



i ton fresh cow dung contains ...................... Ib. N 



How many tons of fresh cow dung would be required to furnish nitro- 

 gen for 10 tons of alfalfa hay? 



