Besides directing many people's research, Pauling used to deliver a freshmen's introductory course of lectures which he first published as a textbook of General Chemistry in 1947. Its 1970 edition contains over 900 pages; it begins with an introduction to the atomic and molecular structure of matter, covers most important aspects of physical and inorganic chemistry, touches on the elements of organic and biochemistry and ends with nuclear chemistry. The lectures were spectacular and often dramatic. Jack Dunitz described one to me: A large beaker filled with what looked like water stood on the bench. Pauling entered, picked a cube of sodium metal from a bottle, tossed it from hand to hand (done safely if your hands are dry) and warned of its violently explosive reaction with water. He then threw it into the beaker. As students cowered in fear of an explosion, he said nonchalantly "but its reaction with alcohol is much milder".