DYNAMICS OF LUMINESCENCE 149 



tration" of pyrogallol and the *^ maximum luminescence 

 concentration ' ' of oxidizer. Table 11 shows this effect 

 of temperature with K4Fe (CN)6 and varying concentra- 

 tions of pyrogallol, and Table 12 shows the effect of tem- 

 perature with pyrogallol and varying concentrations of 

 K4Fe(CN)6. Table 10 shows the relation between tem- 

 perature and intensity of luminescence with pyrogallol 

 and various oxidizers. The terms faint, fair, good, and 

 bright are purely relative designations of brightness as 

 estimated by the eye, for accurate measurements of weak 

 intensities are very difficult to make. 



From Table 10 it should be noted that the intensity of 

 luminescence of pyrogallol oxidized with most oxidizers is 

 actually less at the boiling point, a fact which I have re- 

 peatedly verified. Let us now see how these facts are to 

 be explained. If we assume that luminescence is depend- 

 ent on reaction velocity, the intensity of luminescence 

 should increase with increasing temperature. Up to a 

 certain limit this is what we find, but at temperatures 

 above this limit the intensity of luminescence actually 

 decreases. The duration of luminescence also decreases. 

 There is an optimum temperature for luminescence in 

 many cases and we can only conclude that luminescence 

 depends not on a very rapid reaction velocity but on a 

 certain definite reaction velocity. Assuming that this is 

 true, how can we account for the anomalous fact that in 

 high concentrations of oxygen, phosphorus will not lumi- 

 nesce or that in high concentrations of pyrogallol, there is 

 no luminescence in presence of ozone or of oxidizer and 

 H2O0. Of course with high active mass of oxygen (in case 

 of phosphorous luminescence) or of pyrogallol (in case of 

 pyrogallol luminescence) the reaction velocity must be 



