Chevreul did fundamental work in organic chemistry, wrote influentially about colour, was a pioneer gerontologist, and aged 100 took part in the first-ever photo-interview (with Nadar). He studied under, assisted and succeeded Vauquelin, and also knew Fourcroy, Lamarck, Jussieu, Geoffroy and Cuvier from the Natural History Museum. Gay-Lussac and he patented a better way of making candles. He gave Seurat (who had written to him) a scientific basis for his ideas about colour, and had Faraday, Ampère and Liebig as friends. Wöhler wrote excitedly to Berzelius, another friend and admirer, about meeting him in Paris.