The reports and discussions contained in this volume have been presented at the XVllth Solvay Conference on Chemistry. This was a special Solvay Conference organized jointly by the Solvay Institutes and the National Academy of Sciences of the United States, on the occasion of the 150th anniversary of the establishment of Belgium as an independent state. It was held in Washington. D.C. on April 23-24. 1980.
The first part of the Conference was devoted to the historical role of the Solvay Institutes, and in particular of the Solvay Conferences on Physics and Chemistry, in promoting international scientific cooperation. The second part was devoted to some aspects of chemical evolution. This subject comprises an impressive number of different, yet complementary, questions having an interest in their own right.