432 H. A. Rowland — Electrical Measurement. 



I have developed Maxwell's theory of electric absorption in 

 this manner. Correcting his equations for a small error, I 

 have developed the resistance and capacity of a condenser as 

 follows : 



Let a condenser be made of strata of thicknesses a x a„ etc. 

 and specific induction capacities k x Jc^ etc. and resistances^?^, 

 etc. Then we have 



R - ^ - — 2 -f- - 4 - etc 



K ~ b* b* + b* • 



Where 



etc. 



1 A 2 A 4 



c ~ ° ~~ ¥ + ¥ ~ etc " 



B = -A- 2 + -A-, + etc. 



^=^HA« + A* +etc -f 



B, = (^r j^ s + etc. 



etc. 



Mr. Penniman has experimented in the Johns Hopkins Uni- 

 versity laboratory with condensers by method 25 and found 

 some interesting results. With a mica standard condenser of 

 \ microfarad he was not able to detect any electric absorption, 

 although I have no doubt one of the more accurate methods 

 will show it. 



With a condenser, probably of waxed paper, he found 



Number of complete 



Capacity in 



Apparent resistance 



periods per second. 



microfarads. 



in ohms. 



14*0 





4-64 



139-6 



32-0 





4-96 



34-1 



53*3 





4'96 



20-5 



131-1 





4-94 



5-2 



The first value of the capacity seems to be in error, possibly 

 one of calculation. However, the result seems to show a 

 nearly constant capacity but a resistance increasing rapidly 

 with decrease of period, as Maxwell's formulae shows. The 

 constant value of the capacity remains to be explained. 



