These substances, contained in small glass vessels, are the samples kept by Humphry Davy of some of the elements he discovered through the process of electrolysis. This process involves using an electrical current to split up compound molecules into elements which are the simplest substances you can isolate using chemical means.
Davy was appointed Professor of Chemistry in 1802 and spent his first few years at the Royal Institution working on very practical science, looking into tanning and agriculture. In 1806 he turned the laboratory’s resources to electrical research, reaching the conclusion that electrical attraction holds elements together in compounds.
Davy was able to acquire several huge batteries, which he joined together in a series, in order to carry out his electrolysis experiments. He isolated Potassium from potash in 1807 and shortly afterwards, Sodium. Following this he also isolated and identified Barium, Calcium, Magnesium, Strontium and Boron. Later he proved that Chlorine and Iodine, which were already known to exist, were elements when they were thought to be compounds.