Schönbein discovered ozone, developed more effective explosives, and like his friend (and patent lawyer) Grove, did pioneering work on fuel cells. Liebig and he met while sitting in on lectures at Erlangen; Schelling, met at the same time, became a lifelong friend. Froebel gave him work teaching, and he met his lifelong friends Faraday and Grove while working as a young schoolteacher outside London. In Paris, he attended Gay-Lussac’s and Thénard’s lectures and also met Biot, Dumas and Brongniart. Berzelius corresponded for 17 years, and Faraday for 26. De la Rive (another correspondent) and Oken were also good friends.