JoLY — Radiant Matter. 87 



elements which occur in and around the mica emitted radiant matter, even at 

 the slowest rates, the clear transparency of the mica must long ago have 

 vanished, and the whole become obscured under the effects accumulated 

 during the ages which have elapsed since the formation of the rocks. 



We seem entitled to conclude that the atomic stability and instability 

 which we observe to-day have immutably prevailed during geological time. 



[Explanation of Pi,ate. 



