. Carnegie Institution of Washington publication. STUDIES OF PHOSPHORESCENCE OF SHORT DURATION. 121 and time in seconds as abscissas. Fig. 127, which gives the decay curve for cadmium sulphate with sodium bromide, and exhibits the two straight lines merging into each other, is a typical example. SUMMARY. The most important points brought out by the experiments here de- scribed may be briefly stated as follows: 1. The decay curve when plotted with the values of /"- as ordinates and corresponding values of t as abscissas consists of two straight lines gradually merging into each other. In t
. Carnegie Institution of Washington publication. STUDIES OF PHOSPHORESCENCE OF SHORT DURATION. 121 and time in seconds as abscissas. Fig. 127, which gives the decay curve for cadmium sulphate with sodium bromide, and exhibits the two straight lines merging into each other, is a typical example. SUMMARY. The most important points brought out by the experiments here de- scribed may be briefly stated as follows: 1. The decay curve when plotted with the values of /"- as ordinates and corresponding values of t as abscissas consists of two straight lines gradually merging into each other. In this respect the short-time and long-time phosphorescent compounds seem to be similar. 2. The transition from fluorescence to phosphorescence is gradual, i. e., the curve shows no sign of discontinuity. 3. The shape of the decay curve and the intensity depend upon the time of excitation. 4. The effect of heat treatment is such as to change both the intensity and the rate of decay of phosphorescence. 5. The effect of infra-red on short-time phosphorescence, if it exists at all, is very slight; but its effect on the initial decay of Sidot blende is quite marked. 6. The experiments indicate that at ordinary temperatures all portions of the phosphorescence band decay at the same rate. THE EXPERIMENTS OF MR. CARL ZELLER. The experiments described below deal with the phosphorescence of three groups of compounds, namely, (1) the aniline dyes in their solid form; (2) a group of manganese compounds of known percentage concentration and a group of cadmium compounds, both prepared by C. W. Waggoner; (3) a group of four phosphorescent sul- phides furnished by Leppin and Ql Masche, and prepared by the method of Lenard and Klatt. — The phosphoroscope described on page 109 was used in connection with a special form of photometer, the arrangement of which is indicated in Fig. 128. In the diagram D is the revolving disk of the phosphoroscope, S the ( spark gap, C the phosphorescent sub- -| / n
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