Debate over Gilbert's `electric fluid' and whether one or two fluids were needed to explain attraction and repulsion. Nollet's work on his two-fluid theory, are held in the IET Archives's rare book libraries.
Following William Gilbert's description of the 'electric fluid', early debate over its nature centred around whether one or two fluids were needed to explain attraction and repulsion. The images below depict the experiments conducted by L'Abbe Jean Antoine Nollet an ardent supporter of the two-fluid theory. When Nollet found his theory under attack from Benjamin Franklin's single-fluid/two-state theory, he responded with a series of heated 'Lettres sur l'Electricite', contesting every inaccuracy, exaggeration and perceived falsehood in Franklin's ideas. However, due in part, to Franklin's tremendous reputation the single-fluid theory became the dominant model.