Thaysen, as requested, supplies memories of Weizmann's involvement in aspects of the early history of synthetic rubber: the production of butadiene from butyl alcohol, of butyl alcohol and acetone from carbohydrates, of acetone by fermentation. With his letter, Whitby encloses notes 'Conference on the Acetone-Butyl Alcohol Fermentation' as reported in the Journal of the Society of Chemical Industry, 38, 1919. Whitby was Profesor Emeritus of Rubber Chemistry and Director of Rubber Research, University of Akron, Ohio.