Abstract

Summary In 1874, the Dutch chemist and Nobel prizewinner Jacobus Henricus van 't Hoff (1852?1911) laid the foundations for stereochemistry with a publication in which he openly suggested that molecules were real physical entities with a three-dimensional structure. He visualized this new spatial concept with illustrations, but also with the help of small cardboard molecular models, which he made himself. Some of these models have survived the ravages of time and are among the oldest molecular models in the world still in existence. What is more, they are the first material models of a three-dimensional molecular structure ever made. This article describes the surviving Van 't Hoff models, kept in Museum Boerhaave in Leiden and in the Deutsches Museum in Munich. Special attention is paid to the use of these models and the specific purposes they served. A closer examination of the models and their context reveals that they had an essential part to play in the early development and spread of Van 't Hoff's stereochemistry theory: he put his molecular models not only to versatile use as didactic tools, scientific instruments, and precursors to experimental proof, but also as devices to persuade other scientists of the usefulness of his theory