The basic idea in much of this work is that high-energy radiation can be used to introduce defects in a partly controllable way into solids, that these defects may influence various manifestations of reactivity, and that the altered reactivity can therefore be attributed to a specific entity in the solid. This attribution requires, of course, knowledge of the defects produced, knowledge sometimes available in advance, but sometimes requiring further experimental study. It would be well to remark here that knowledge of physical radiation damage is not so far ahead of that of reactivity that...