Vari'ation in the Intensities of Mercury Spectrum Lines with Pressure of the Vapor

The relative intensities of spectrum lines of Hg vapor in the d.c. arc and at a pressure of ${10}^{-3\mathrm{}}$ mm in a high frequency electrodeless discharge have been measured for wave-lengths ranging from 7000 to 3000A. There is a decided increase in intensity, relative to the triplet line 5460, of the singlet members in the low pressure discharge, the sharp series showing the greatest increases. The relative intensity increases rapidly with ascending members of the series. Five new lines in the sharp singlet series were observed. Combination singlets appeared strong in the red in the low pressure discharge. The first members of the triplet series do not show much change but the higher members show an increasing intensity at low pressure. Combination lines also show decided increase in the low pressure discharge.