FOODS. ~ 



happens ? Cool under the faucet and add the ammonium 

 hydrate. What happens ? The color is characteristic. 



b. Second test : Piotrowski's Reaction. 



Materials. 5c.c. of proteid solution. 10c.c- of a concentrated 

 solution of sodium hydrate. 2-3 drops of a one per cent solution of 

 cupric sulphate. 



Apparatus. Test-tubes. Test-tube rack. Bunsen burner. 



Experiment : 



To the proteid solution add the sodium hydrate and 

 then the cupric sulphate. What color is obtained ? BoiL 

 What change is there in the color? This test detects the 

 smallest traces of all proteids. 



c. Third test. 



Materials. 5 c.c. of proteid solution. 5 c-c. of acetic acid- 3-4 

 drops of potassium ferrocyanide. 

 Apparatus. Test-tubes. 



Experiment : 



To the proteid solution add the acetic acid and then 

 the ferrocyanide. What occurs ? 



II. EXAMINE MLLK FOR PROTEIDS. 



10 C.C. of milk. 10 C.C- of water. 5 c-c_ of acetic 

 acid or vinegar. 10 c.c. of lime-water. 10 c.c- of a concentrated 

 solution of sodium hydrate. 23 drops of a dilute solution of cupric 

 sulphate, 



Apparatus. Test-tubes. Test-tube rack. Bunsen burner. Filter- 

 paper. FunneL 



Experiment : 



l. Dilute the milk with the water and add the 

 acetic acid. What happens? This precipi- 

 tate is the proteid, casein. 



