one half of the albumen make a 10 per cent solution. To do this, 

 place in an evaporating dish and cut the albumen up with scissors * 

 this frees it from membranes. Then mix with () times its volume 

 of distilled water, stirring thoroughly ; filter. Keep the undiluted 

 half for further use. 



2. COAGULATION, (i) Coagulation by heat. Have a water 

 bath with water at the boiling temperature. Put some of the un- 

 diluted albumen in a test tube and place in the water bath. Does 

 it coagulate? Try a little of the 10 per cent solution in the same way. 

 Does it coagulate? What is the effect of dilution on coagulation by 

 heat? (2) Coagulation by chemicals. To 5 cc. of the 10 per cent 

 albumen add a few drops of 3 per cent copper sulphate. Try also 

 strong nitric acid and sulphuric acid, allowing a drop or two to run 

 down the side of the test tube. Try also 95 per cent alcohol. 

 (3) Manner in which coagulation takes place. Dip a thin thread of 

 silk in a 3 per cent solution of copper sulphate and lay the thread 

 on a glass slide beneath a cover glass. Allow some of the 10 per 

 cent solution of white of egg to run under the cover while observ- 

 ing the operation with high power of the microscope. The albumen 

 about the thread will be seen to form small granules appearing like 

 a fine cloud, and these later run together and form a network. 



3. CHEMICAL TESTS FOR PROTEIDS. (i) Xanthoproteic Reaction. 

 Dilute some of the 10 per cent albumen till it is about 2 per cent ; 

 place a small quantity in a test tube. Add a few drops of nitric 

 acid. What occurs ? Boil. What occurs as to color and other 

 changes ? Cool the solution and add ammonia until saturated. Xote 

 color produced. (This is the essential feature of this reaction.) 

 Try in the same way a weak solution of gelatin (albuminoid) ; does 

 it give the xanthoproteic reaction? Try this reaction also with 

 water containing many infusoria ; first heat the water containing 

 the animals, then add the nitric acid and ammonia. What results? 



4. ACTION OF ENZYMES ON PROTEIDS. Place thin pieces of boiled 

 white of egg in artificial gastric juice, made by adding pepsin to a 

 0.2 per cent solution of hydrochloric acid ; label and allow to stand 

 till next day. Place some of this digested albumen in one dialyzer 

 and some fresh, undiluted albumen in another ; after one hour test 

 the water below each dialvzer for albumen. 



