ABSTRACT
The first determination of the spectrum of the radium emanation was made in 1904 by Ramsay and Collie, who obtained visual observations of the wave-lengths of eleven lines. They stated that the emanation was a bright line spectrum similar in general character to that observed for other monatomic gases. In order to test the purity of the emanation, an electrodeless discharge was passed in the capillary tube in which the volume of the emanation was measured, and visual observations of the wave-lengths of the main ines were made by means of a direct reading Hilger spectroscope. The measurements of the wave-lengths of the lines common to the two plates agreed within the limits of experimental error. The wave-lengths were deduced with the aid of the Hartmann dispersion formula. The colour of the discharge through the emanation was bluish and not so intense as the helium tube.
