﻿672 



Dr. T. S. Taylor on the Number of 1 



ons 



The standard condenser used was a Leeds and Norfchrup 

 microfarad condenser having elements 0*5, 0*2, 0*2, 0*05, and 

 0*05 microfarad. The calibration of this condenser shows 

 the above values to agree with Leeds and Northrup's 

 standard capacity within one fourth of a per cent. By 

 connecting the elements of this condenser in series, capacities 

 of 0*025 and 0*02 microfarad were obtained. In this 

 determination care was taken to shield the connecting wires 

 joining the auxiliary condenser and the standard condenser 

 to the measuring system from outside electrostatic influences. 

 This was done by enclosing all connecting wires in earthed 

 metal conductors. Mercury contact-keys were used in 

 making the connexions between the auxiliary condenser, the 

 standard condenser, and the measuring system, so that either 

 condenser could be joined in parallel with the measuring 

 system as desired. 



A potentiometer scheme was used for charging the outer 

 coating of the auxiliary condenser. This consisted of several 

 100,000 ohm resistance-coils and coils ranging from 1 to 

 100,000 ohms, in series with a 500 volt storage-battery. By 

 this means, any fractional part of the 500 volts could be 

 applied to the outer coating of the auxiliary condenser. 

 Using values of the standard condenser equal to 0'025 and 

 0"02 microfarad, respectively, the values of the capacity of 

 the measuring system as recorded in Table I. were found. 



Table I. 



i 



Value of standard capacity 

 used, in microfarads. 



Calculated capacity of the 



measuring system, in 



electrostatic units. 



o o o © o 

 6 6 6 6 6 



55-3 



54-8 

 54-9 

 55 4 

 54-8 



Mean 55'0 



The greatest variation from the mean value is seen to be less 

 than one-half per cent., which is as small a variation as one 

 might expect to obtain in the determination of so small an 

 electrostatic capacity. 



