Although best known today for the eponymous Bunsen burner, German chemist Robert Wilhelm Eberhard Bunsen (Wikipedia), born on this date in 1811, had a foundational role in many areas of modern chemistry. He discovered the use of iron oxide hydrate as a precipitating agent for arsenic, which even today has applications in treating contaminated groundwater. His experiments with arsenic cost him an eye (by an explosion of pyrophoric tetramethyldiarsine) and almost cost him his life, by poisoning. He invented the Bunsen cell, an early electrochemical “battery” that improved upon existing designs by replacing precious metallic platinum with common carbon in the cathode. He used his new cell, among other things, to isolate pure magnesium for the first time, by electrolysis. With Kirchoff, he was instrumental in the development of flame-emission spectroscopy, and used the technique, for which his famous burner was developed, to discover two then-unknown elements–cesium and rubidium. He was, even among the acerbic European academic chemists of his day, widely regarded for his kindness, even temperament, and good character. He died in 1899, aged 88.