56 



TABLE III 

 PARAMETER b FROM GERRITSEN'S CONDUCTIVITY MEASUREMENTS 



The way we interpreted these results when we first saw them was that mol- 

 ecules have an effective mechanism for dissipation of electron energy. The 

 electrons get quite far away if they have positive energy and there is only minor 

 dissipation due to elastic collisions. But if they have in addition any other 

 mechanism of dissipation, apparently the evidence seems to be that they are 

 trapped in a lot closer. Davidson et al (9) report that they cannot get any con- 

 duction in liquid N2 at all. 



These conductivity results cannot be understood without careful analysis, 

 and I am just calling your attention to them. They furnish a line of evidence 

 which I think indicates that energy dissipation in molecules may be quite ef- 

 fective in stopping electrons leaving positive charges. 



Now I will come to the part I think we should discuss most thoroughly, and 

 this will probably be of more interest to biologists. It is the chemical evidence. 

 Samuel and I had in mind, when we started looking at all of this picture, that 

 we wanted to put together a radical diffusion model for chemical effects of ra- 

 diation on water. For this we wouldn't really need to specify the radical for- 

 mation mechanism. 



I am not really tying all of this together as a complete and continuous theory. 

 It is just a sort of fragmentary discussion. For example, what I am telling you 

 now does not depend on the previous electron capture discussion as a founda- 

 tion. 



I hesitate to talk about water with so many radiation chemists in our midst, 

 but with their help this discussion can turn out to be quite profitable. Let's 

 take, for example, the effect of gamma rays on water. You remember that in 

 the case of high- energy gamma rays, most of the primary events which will 

 take place will be formed isolated from each other. I don't think anybody will 

 argue that any effects are transmitted directly from one primary event to an- 

 other. The effects of irradiation can be summarized this way: water decom- 



