Human Foods and Their Nutritive Value

by Harry Snyder

Experiment No. 4

Nitric Acid Test for Nitrogenous Organic Matter

To 3 cc. of egg albumin in a test tube add 2 cc. of HNO₃ (conc.) and heat. When cool add NH₄OH. The nitric acid chemically reacts upon the albumin, forming yellow xanthoprotein. What change occurs in the appearance of the egg albumin when the HNO₃ is added? Is this a physical or chemical change? What is the name of the compound formed? What change occurs on adding NH₄OH?