Discovery made by Luigi Brugnatelli, professor of chemistry, Italy.

Technique used for electro-reduction of metals and the ‘reviving’ of gold involved ‘gilting two large silver medals, by bringing them into communiation by means of a steel wire, with the negative pole of a voltaic pile, and keeping them one after another immersed in gold solution’.

Immersion gilding (or water gilding) of trinkets in dilute gold solution were produced cheaply. But mercury gilt used for other items (eg spectacle frames) was a dangerous process and resulted in many deaths and disabling diseases.