Professor Harold C. Urey, of Columbia will give a free public lecture entitled "The Problem of the Concentration of Isotopes" in the Fogg Museum this evening at 8:15 o'clock under the auspices of the Harvard chapter of he society of Sigma Xi.

Dr. Urey is one of the leading authorities in the field of chemistry. His discovery of heavy water three years ago created a sensation in the scientific world, and for this research he received in 1984 the Nobel prize in chemistry.

Hydrogen Discoveries

Authorities state that his discoveries in the field of hydrogen have revolutionized the progress of research in chemistry, physics, and biology.