663 



lies ill this that (ho lines of tbroo between a and h, which are 

 subjected to a change on ionisation, will mostly ariee on odi' side 

 of the vertical strip. This removes the last mentioned drawback, a 

 large injurious horizontal surface also being avoided. I think that 

 with this apparatus I have obtained a sensibility of charge, greater 

 than is possible with a DoLEZALKK-electrometer, the same thickness 

 of wire given. 



The realization of a greater sensibility of charge. 



The sensibility of the apparatus appeared to be capable of great 

 variation, the suspension wire being left unaltered, and that by 

 varying the state, of charge, whereas, for the rest, the method of 

 charging and measuring remains the same. To make the system 

 more sensitive, a is not charged to + 20 V, but say to -|- 32 V, 

 after which a negative potential value is imparled to c such that a 

 has turned back to an almost untwisted position. The potential of 

 c will also be more strongly negative, of course, for this state than 

 for the state (-f 20.0, — 3) V; the state of charge will then become 

 e. g. (+ 32,0, - 6) V. 



In order to understand what causes this modification of charge to 

 bring about greater sensibility of charge, we must examine in the 

 apparatus 1. the variation of the potential sensibility. 2, the variation 

 of the value of the capacity ; for these two factors together determine 

 the sensibility of charge. 



i. The former is to be found from the curves I, in which examples 

 of some states of charge are given ; to investigate the potential 



Cl 



iO 



'Uetti 



^0 



Fie;. 1. 



Proceedings Royal Acad. Amsterdam, Vol. XVII. 



44 



