This translation, in two volumes, of an introductory paper to a Symposium on Chemical Kinetics and Reactivity, held in Moscow in 1954, has been enlarged and revised by the author, winner of the Nobel Prize in chemistry in 1956 and one of the two or three top flight Russian physical scientists. Volume 1 covers a wide range of important work and includes a survey of radical and chain reactions and a discussion of chemical changes, direct mono- and bi-molecular processes, ionic reactions, heterogeneous catalysis, initiation and destruction of radical chains on solid surfaces. Originally published in 1958. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.