DECAY OF PHOSPHORESCENCE PRODUCED BY HEATING. 



103 



600 seconds excitation is greater than that for any shorter excitation at the 

 same temperature. At a temperature near ioo C, the second flash is no 

 longer evident in the curves. 



40 



80 



120 



160 2.00 Z44 



Fig. 107. 



060 Sec. 



Effect of varying the length of excitation. Excited and allowed to decay at room temperature to / =2.9, 

 when heating was begun. Temperature of furnace, 277 C. 

 Curve A, excited 600.2 sec. Curve D, excited 60.7 sec. 



B, " 300.0 E, " 30.1 



C, " 150. 1 F, " 14.8 



60 



Fig. 108. 



HO 



Sec. 



Curves similar to Fig. 107. Temperature of furnace, 339 C 

 Curve 1, excited 600.0 sec. Curve 4, excited 59.8 sec. 



2, " 300.0 5. " 29.8 



3, " 150.1 6, " 14.2 



