[kobertson] 



INSULATED METALLIC CONDUCTORS 



121 



later only 13. Another good illustration of this is the case of lead 

 No. 1 in lead No. 3 (vide Table I, Nos. 12 and 13), where the maximum 

 value of the positive charge increased in fourteen days from 22 to 42 

 millivolts. 



These results would seem to indicate the growth of a deposit or 

 deposits removable by cleaning, which resulted in the insulated cylinders 

 gaining a positive charge, and here we may have an explanation of 

 the high positive charge which McKeon found for his lead combination. 



TABLE VI. 



Zinc in zinc. Without radium. 



It is known that on old lead, such as McKeon used, radioactive deposits 

 are gradually formed, and on this account, there would be an emission 

 of charged particles from both the inner and the outer cylinders. It 

 is evident that this might result in a difference in the number of charged 

 particles coming to the insulated cylinder and in the number leaving it. 

 It could then happen that the insulated cylinder would acquire a posi- 

 tive charge, the magnitude of which would be largely determined by the 

 nature of the active deposit. 



