EXPERIMENTS 271 



Experiment No. 21. 

 Volatilization of Ammonium Salts. 



In separate test tubes, place about .1 gtn. each of ammonium car- 

 bonate and ammonium sulphate. Apply heat gently to each and 

 observe the result. Observe that the ammonium carbonate readily 

 volatilizes and some is deposited on the walls of the test tube while 

 the ammonium sulphate is much less volatile. In poorly venti- 

 lated barns, deposits of ammonium carbonate are frequently found. 



Experiment No. 22. 

 Testing for Phosphoric Acid. 



Dissolve .5 gm. bone ash in 15 cc. H 2 O and 3 to 5 cc. HNO 3 and 

 filter. To the warm filtrate, add 5 to 7 cc. ammonium molybdate 

 and shake. The yellow precipitate formed is ammonium phospho- 

 molybdate. See Experiment No. 17. 



Experiment No. 23. 



In a test tube, heat .5 gm. of bone ash with 20 cc. distilled 

 H 2 O ; filter. To the warm filtrate, add 5 cc. ammonium molyb- 

 date and shake. Note the result as compared with that when 

 HNO 3 was used with the distilled water. What does the result 

 show ? 



Experiment No. 24. 

 Preparation of Acid Phosphate. 



Place 100 gms. bone ash in a large lead dish. Add slowly and 

 with constant stirring 100 gms. commercial sulphuric acid, using 

 an iron spatula for the purpose. Transfer the mixture to a wooden 

 box and allow it to act for about three days. Then pulverize and 

 examine. The mixing of the acid and phosphate should be done 

 in a place where there is a good draft. Test y z gram for water 

 soluble phosphates as directed in Experiment No. 23. 



Experiment No. 25 



Solubility of Organic Nitrogenous Compounds in Pepsin Solution. 

 Prepare a pepsin solution by dissolving 5 gms. of commercial 

 pepsin in a litre of water, adding i cc. of strong HC1. Place in 

 separate beakers .5 gm. each of dried blood, tankage and bone ash. 

 Add 200 cc. of pepsin solution to each and place the beakers in a 

 water bath kept at a temperature of about 40 deg. C. Stir occasion- 



