536 KINETICS OF BIOLUMINESCENT REACTION. II 



along its curve, it is fundamental to inquire what relation exists 

 between reaction velocity and the resulting light intensity. Trautz^ 

 from an extensive study of chemiluminescent reactions, but without 

 actual quantitative data, arrived at the conclusion that light intensity 

 is proportional to the velocity of reaction, and therefore a direct 

 measure of it. He based his conclusions upon the observed increase 

 of Hght intensity in such reacting solutions with the increase of tem- 

 perature, and upon other similar considerations. Such qualitative 

 observations are by no means adequate to establish such a quanti- 

 tative hypothesis, but certainly point in the direction of its truth. 



In the related field of true inorganic phosphorescence the most 

 comprehensive theory which has yet been proposed is that of Wiede- 

 mann and Schmidt,^ which, in its most general form, supposes that 

 some chemical or physical change is produced in a luminescent 

 material while the exciting radiation is impinging upon it, and that 

 the luminescence which persists when excitation ceases is an expression 

 of the gradual restoration of the original state with the emission of 

 light. More specifically it is generally believed that the effect of the 

 exciting radiation is to split a portion of the luminescent material 

 into equal members of positive and negative particles, probably 

 ionic in nature, and that the luminescence which appears is due to 

 the recombination of these ions at a definite rate. Accurate deter- 

 minations of the law of decay of light in such materials have given 

 values which fit in well with this hypothesis, if the emitted light is 

 taken to be a direct measure of the number of recombinations at any 

 instant, for it has been found that if the reciprocal of the square root 

 of the light intensity be plotted against time a straight line will connect 

 all the points, and this is the theoretical expectation if two substances, 

 present in equal concentrations, are combining together under the law 

 of mass action. In other words, true inorganic phosphorescences 

 appear to follow the kinetics of a stoichiometric bimolecular reaction.' 

 While the theory was originally proposed to explain the form of the 



^ Trautz, M., Z. physik. Chem., 1905, liii, 1. 



2 Wiedemann, E., and Schmidt., C. C, Wied. Ann., 1895, Ivi, 177. 



' It has been found, however, that this is not true at all temperatures, and that 

 some other power of / than | may better accord with the experimental observa- 

 tions. See Ives, H. E., and Luckiesh, M., Astrophys. J., 1912, xxxvi, 330. 



