In October 1859, German physicist Gustav Kirchhoff announced the results of his investigations with chemist Robert Bunsen on the dark lines that interrupt the otherwise continuous solar spectrum (1). These lines had puzzled practitioners and theorists alike since they were first observed in 1814 by German optician Josef von Fraunhofer (2).
Now it seemed that Bunsen and Kirchhoff had finally confirmed what others had long suspected, namely, that an individual metal produces its own characteristic pattern of bright spectral lines when it is burned. …
