Changes produced iii Matter hy Electric Waves. 467 



The curve given in fig. 3 clearly exhibits the reversals. This curve 

 also explains the behavioiu* of magnesium noticed in my last paper, 

 which appeared very curious at the time. " It is sometimes possible 

 to so adjust matters that one flash of radiation produces a diminution 

 of resistance, and the very next flash an increase of resistance. Thus 

 a series of flashes may be made to produce alternate throws of the 

 galvanometer needle."* 



The receiver was so adjusted as to give a deflection of five divisions. 



iime of exposure 



Fig. 3. — Badio-molecular Oscillation Curve for Magnesium. 



The first flash of radiation produced an increased deflection of 90 

 ■di^dsions (magnesium having a positive electric touch) ; the second 

 flash produced a further deflection of five divisions, the third flash 

 produced a negative deflection of five divisions, the fourth flash pro- 

 duced + 5, the fifth flash gave - 90 divisions, and the sixth flash a 

 deflection of + 90. The reversals followed each other almost regu- 

 larly, till the substance became insensitive. 



III. Lastly, we may have a class of substances where the conver- 

 sion from one state to the other is not complete. Here, again, we get 

 two sub-diidsions, owing to the distinction between positive and 

 negative substances. 



Taking first the case of a positive substance (see fig. 4 (/5) ), the 

 original conducti\ity of which is represented by a, the action of the 

 first few flashes of radiation would be to produce a great increase of 

 <!onducti\dty by the formation of B variety ; the next flashes convert 



Eia. 4. — " Damped" Molecular Oscillation. 



* " On a Self-recorering Colierer," kc, ' Roy. Soe. Proc.,' vol. 65, p. 169. 



2 o 2 



