IT is known that many organic compounds in solid solutions show two kinds of afterglow besides fluorescence: phosphorescence (α-band) and fluorescence of long duration (β-band). The α-band is almost identical with that of fluorescence, while the β-band is of lower frequency. One of us has already shown1 that for fluorescein in boric acid glass the maximum of α-band is shifted in direction of long waves by about 60 Å with regard to maximum of fluorescence band. The α- and β-processes can be explained by the Jabłoński electronic level diagram2. The α-phosphorescence increases rapidly with temperature, while the β-phosphorescence is far less dependent on temperature. Consequently, the β-band is observed at low temperatures.