DIGESTION AND ABSORPTION. 163 



() Saline solution of myosin. 

 (<r) Syntonin in acid solution. 

 (X) Acid albumin in acid solution. 

 (e) Gelatin in aqueous solution. 

 (/) Proteoses. 

 () Peptone. 



Record the results in a table and formulate con- 

 clusions. 



(2) Subject the same series of proteids to the cold nitric 

 acid test by first pouring one or two cubic centimeters of 

 strong nitric acid into a test tube, then with pipette care- 

 fully floating the proteid liquid upon it. In the case oi 

 dilute egg albumin a characteristic white ring forms 

 between the acid and the albumin. Note in each case 

 whether or not a typical ring is formed. 



(#) Dilute egg albumin. 



() Saline solution of myosin. 



(*T) Syntonin. 



(</) Acid albumin. 



(<?) Gelatin. 



(/) Proteoses. 



() Peptone. 



Tabulate results and formulate same in a concise 

 statement. 



(3) The Xanthoproteic test. 



Use the tubes and materials already prepared in the 

 cold nitric acid test. Shake the tubes to mix the acid 

 with the proteid. In some cases a coagulum will be 

 formed and this coagulum turns yellow on boiling if 

 the tube is held in a Bunsen flame. After the coagu- 

 ium has been boiled in the acid, cool under the hydrant 

 or in a pail of ice water and add strong ammonia to 

 alkaline reaction. The light yellow coagulum which 

 forms in the case of egg albumin turns to an orangecolor. 



