The peculiar properties of natural and artificial plastics. Lawrence Bragg first compares naturally and artificially produced plastics and describes their structure. Demonstrations illustrate how simple molecules, by chemical reaction, are transformed into macro-molecules. This section of the film concludes with an experiment showing the manufacture of a plastic. The construction of rubber is then described, its nature being illustrated both experimentally and with the aid of models. Crown copyright information is reproduced with the permission of the Controller of HMSO and the Queen’s Printer for Scotland.