56 SECTIONAL ADDRESSES. 



the initial complex being an adsorption complex of carbonic acid and 

 nickel carbonate. There should exist, therefore, a lower temperature 

 limit below which the reaction will not take place ; an intermediate 

 temperature zone in which the reaction will take place with a definite 

 temperature coefficient ; and an upper limit of temperature at which all 

 reaction again ceases. These three phenomena have been observed, and 

 the photosynthetic and photoluminescent processes proved to be analogous. 

 In the one the highly activated molecules undergo chemical reaction, in 

 the other they emit their critical quanta of activation as visible radiation. 

 It may be claimed that the evidence brought forward from the three 

 fields of photoluminescence, absorption spectra and chemical reaction 

 constitutes a story that is not without interest. The one dominating 

 influence in this story is the critical quantum of activation which has 

 found its experimental verification. In laying down the pen of authorship 

 I do so in the confident hope that a definite step has been gained towards 

 a radiation theory of chemical reaction. 



