Newton descovered that the white light was composed by all the rainbow colors.
More information about Newton's experiment.
He observed a relation between the color and the temperature and he discovered the infrared light.
More information about Herschel's experiment.
He discovered the ultraviolet light with a paper weted of silver chloride.
More information about Ritter's experiment.
He discovered the Fraunhofer's lines (black lines of the spectrum of the white light)(570 lines aprox).
More information about Fraunhofer's experiment.
They said that the ideal body was a black body, it has an continuous spectrum (without black lines). They got it burning chemical substances and passing them for a prism to observe the emission peaks (emission spectrum).
More information about Kirchhoff and Bunsen's experiment.