236 



Mr. D. 0. H. Florance <m 



Fis. 6. 



C Al 



MASS PER UNIT AREA. 



Electroscope in position E 3 



MASS PER UMTAREA. 



Electroscope in position E 4 . 



When equal weights (470 grs.) of the four radiators are 

 used, carbon does not always produce more secondary radia- 

 tion than aluminium. This had been observed in the earlier 



