Evidence for Spectral Lines Spectral lines were first seen in
the sun's spectrum by William Wollaston in 1802. However, they
were not systematically studied until 1814, when a German
optician named Joseph von Fraunhofer observed and catalogued
them. Fraunhofer carefully recorded the positions of the lines,
but he didn't attempt to explain why they were there. In the
late 1850's, the physicist Gustav Kirchhoff decided to
investigate further, with the help of the chemist Robert Bunsen.
Did he invent the Bunsen burner? And they found that each
element had its own unique set of lines? They certainly did. A
given element would always produce the same spectrum, which was
different from that of any other element. In fact, in the
1860's, Kirchhoff and Bunsen discovered two new elements, cesium
and rubidium, when they came across some spectral lines that
didn't fit any of the known elements. Later, the elements of
gallium, helium, argon, neon, krypton, and xenon were also
discovered using spectroscopy.