74 PHYSIOLOGY FOE THE LABORATORY. 



2. Filter. What is the filtrate ? 



3. Add a little of the casein to water and shake. 



Is the casein soluble in water? 



4. Add a little of the casein to lime-water and 



shake. Is it soluble? 



5. Test milk by the second method above for 



proteid. 



6. Boil some milk. Does the casein coagulate? 



Compare this result with the action of heat 

 upon egg-albumin. 



III. TEST CHEESE FOR PROTEIDS. 



Materials. A small piece of cheese. 25 c.c. of lime-water. 10 c.c. 

 of sodium hydrate (concentrated). 2 or 3 drops of cupric sulphate. 



Apparatus. Test-tube. Filter-paper. Funnel. Bunsen burner. 

 Evaporating dish. 



Experiment : 



1. Thoroughly mix a small piece of cheese with 



about 25 c.c. of lime-water. 



2. Filter. Is the ' proteid in the precipitate or 



filtrate ? 



3. Test for proteid by the second test above. 



4. From what is cheese made? 



5. What proteid is in milk ? 



6. What proteid is in cheese ? 



IV. EXAMINE MUSCLE FOR PROTEIDS. 



Materials. A piece of lean beef. 25 c.c. of 10 per cent solution 

 of ammonium chloride. Lime-water. 20 c.c. of a concentrated solu- 

 tion of sodium hydrate. 4-6 drops of cupric sulphate. Alcohol, 75 

 per cent solution. 



Apparatus. Evaporating dish. Filter-paper. Test-tube. Bun- 

 sen burner. Funnel. 



