DECAY OF PHOSPHORESCENCE PRODUCED BY HEATING. 



1 05 



in the case of the second flash is shown in Fig. in. These curves indicate 

 that an increase in the length of excitation beyond a certain length does 

 not increase the maximum intensity, but decreases it. 



150 



300 



Seconds 



600 



Fit 



in. 



Maximum intensity of the second flash plotted against length of excitation. 

 Curve A, temp, of furnace, 339 C (from Fig. 108). 



B, " " " 277 (from Fig. 107). 



C. " " " 222 



The relation between the maximum intensity of the second flash and 

 the temperature is shown in Fig. 112. This figure corresponds closely to 

 Fig. 1 10, which shows the corresponding relation for the first flash. 



Fig. 113 shows the effect of delay in heating and Fig. 114 the same 



30 

 20 

 10 



Fig. 112. 



Maximum intensity of the second flash plotted against 

 temperature of the furnace. 

 Curve B, 



C. 



o, 



E, 

 F, 



excited 300 sec. 



150 



60 



30 



15 



100- 



200 v 



300 



Fig. 113. 



Effect of delay in heating. Time measured from end of excitation. Excited 60 seconds at room temperature. 

 Temperature of furnace, 228 C. Curve .1, decay at room temperature. The time between the end 

 of excitation and the beginning of heating is as follows: Curve B, 2.1 seconds; C, 25.6; D, 101.7; E 

 203.2; F, 401.7; G, 801.7. 



